As filed with the Securities and Exchange Commission on March 22, 2021.

 

UNITED STATES SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form 20-F

 

ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d)
OF THE SECURITIES EXCHANGE ACT OF 1934

 

For the fiscal year ended: December 31, 2020
Commission file number: 001-38256

 

NEXA RESOURCES S.A.

(Exact name of Registrant as specified in its charter)

 

Grand Duchy of Luxembourg

(Jurisdiction of incorporation or organization)

 

Rodrigo Menck

Senior Vice President Finance and Group Chief Financial Officer
Phone: +352 28 26 37 27

37A, Avenue J.F. Kennedy
L-1855, Luxembourg
Grand Duchy of Luxembourg
(Address of principal executive offices)

 

Securities registered or to be registered pursuant to Section 12(b) of the Act:

 

Title of Each Class

Trading Symbol

Name of Each Exchange on Which Registered

Common shares, each with par value of US$1.00 NEXA New York Stock Exchange

Securities registered or to be registered pursuant to Section 12(g) of the Act: None
Securities for which there is a reporting obligation pursuant to Section 15(d) of the Act: None
The number of outstanding shares of each class of stock of Nexa Resources S.A. as of December 31, 2020 was:

132,438,611 common shares, each with par value of US$1.00

 

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.

Yes ¨ No þ

 

If this report is an annual or transition report, indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934.

Yes ¨ No þ

 

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports) and (2) has been subject to such filing requirements for the past 90 days.

Yes þ No ¨

 

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).

Yes þ No ¨

 

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer or an emerging growth company. See definition of “accelerated filer,” “large accelerated filer” and “emerging growth company” in Rule 12b-2 of the Exchange Act. (Check one):

 

Large accelerated filer ¨ Accelerated filer þ Non-accelerated filer ¨ Emerging growth company ¨

 

If an emerging growth company that prepares its financial statements in accordance with U.S. GAAP, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards† provided pursuant to Section 13(a) of the Exchange Act. ¨

 

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report. þ

 

Indicate by check mark which basis of accounting the registrant has used to prepare the financial statements included in this filing:

U.S. GAAP ¨ International Financial Reporting Standards as issued by the International Accounting Standards Board þ Other ¨

 

If “Other” has been checked in response to the previous question, indicate by check mark which financial statement item the registrant has elected to follow.

Item 17 ¨ Item 18 ¨

 

If this is an annual report, indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).

Yes ¨ No þ

 

 

 

 

 

 

Table of contents

 

      Page  
  Form 20-F cross reference guide     iii  
  Forward-looking statements     1  
  About the Company     3  
  Presentation of financial and other information     4  
  Risk factors     6  
  Selected financial data     21
           
I. Information on the Company     34  
  Business overview     34  
  Mining operations     39  
  Smelting operations     70  
  Other operations     73  
  Mineral reserves and resources     81  
  Capital expenditures     90  
  Regulatory matters     91  
           
II. Operating and financial review and prospects     98  
  Overview     98  
  Results of operations     110  
  Liquidity and capital resources     117  
  Contractual obligations     123  
  Off-balance sheet arrangements     124  
  Critical accounting policies and estimates     125  
  Risk management     128  
           
III. Share ownership and trading     131  
  Major shareholders     131  
  Related party transactions     132  
  Distributions     135  
  Trading markets     137  
  Purchases of equity securities by the issuer and affiliated purchasers     138  
           
IV. Corporate governance, management and employees     139  
  Corporate governance     139  
  Board of directors     144  
  Executive officers and management committee     153  
  Executive and director compensation     157  
  Employees     161  
           
V. Additional information     162  
  Legal proceedings     162  
  Articles of association     163  
  Taxation     167  
  Exchange controls and other limitations affecting security holders     175  
  Evaluation of disclosure controls and procedures     176  
  Internal control over financial reporting     177  
  Principal accountant fees and services     178  
  Information filed with securities regulators     179  
  Glossary     180  
  Exhibits     183  
  Signatures     184  
  Nexa Resources S.A. Financial Statements     185  

 

ii

 

 

Form 20-F cross reference guide

 

FORM 20-F CROSS REFERENCE GUIDE

 

Item Form 20-F caption Location in this report Page
1 Identity of directors, senior management and advisers Not applicable
2 Offer statistics and expected timetable Not applicable
3 Key information    
  3A Selected financial data Selected financial data 21
  3B Capitalization and indebtedness Not applicable
  3C Reasons for the offer and use of proceeds Not applicable
  3D Risk factors Risk factors 6
4 Information on the Company    
  4A History and development of the Company About the Company, Business overview, Capital expenditures 3, 34, 90
  4B Business overview Business overview, Mining operations, Smelting operations, Other operations, Mineral reserves and resources, Regulatory matters 34, 39, 70, 73, 81, 91
  4C Organizational structure Business overview, List of Subsidiaries 34, Exhibit 8
  4D Property, plant and equipment Mining operations, Smelting operations, Other operations, Capital expenditures, Regulatory matters 39, 70, 73, 90, 91
4A Unresolved staff comments None
5 Operating and financial review and prospects    
  5A Operating results Results of operations 110
  5B Liquidity and capital resources Liquidity and capital resources 117
  5C Research and development, patents and licenses, etc. Business overview 34
  5D Trend information Results of operations 110
  5E Off-balance sheet arrangements Off-balance sheet arrangements 124
  5F Tabular disclosure of contractual obligations Contractual obligations 123
  5G Safe harbor Forward-looking statements 1
6 Directors, senior management and employees    
  6A Directors and senior management Board of directors, Executive officers and management committee 144, 153
  6B Compensation Executive and director compensation 157
  6C Board practices Corporate governance, Board of directors 139, 144
  6D Employees Employees 161
  6E Share ownership Board of directors—Share ownership 152
7 Major shareholders and related party transactions    
  7A Major shareholders Major shareholders 131
  7B Related party transactions Related party transactions 132
  7C Interests of experts and counsel Not applicable
8 Financial information    
  8A Consolidated statements and other financial information Nexa Resources S.A. Financial statements, Distributions, Legal proceedings 185, 135, 162  

 

iii

 

 

Form 20-F cross reference guide

 

  8B Significant changes Not applicable
9 The offer and listing    
  9A Offer and listing details Trading markets 137
  9B Plan of distribution Not applicable
  9C Markets Trading markets 137
  9D Selling shareholders Not applicable
  9E Dilution Not applicable
  9F Expenses of the issue Not applicable
10 Additional information    
  10A Share capital Not applicable
  10B Memorandum and articles of association Articles of association 163
  10C Material contracts Business overview, Results of operations, Related party transactions 34, 110, 132
  10D Exchange controls Exchange controls and other limitations affecting security holders 175
  10E Taxation Taxation   167
  10F Dividends and paying agents Not applicable
  10G Statement by experts Not applicable
  10H Documents on display Information filed with securities regulators 179
  10I Subsidiary information Not applicable
11 Quantitative and qualitative disclosures about market risk Risk management 128
12 Description of securities other than equity securities    
  12A Debt securities Not applicable
  12B Warrants and rights Not applicable
  12C Other securities Not applicable
  12D American Depositary Shares Not applicable
13 Defaults, dividend arrearages and delinquencies Not applicable
14 Material modifications to the rights of security holders and use of proceeds Not applicable
15 Controls and procedures Evaluation of disclosure controls and procedures, Internal control over financial reporting 176, 177
16A Audit committee financial expert Board of directors—Committees of our board of directors—Audit committee 150
16B Code of ethics Corporate governance—Code of conduct 139
16C Principal accountant fees and services Principal accountant fees and services 178
16D Exemptions from the listing standards for audit committees Not applicable
16E Purchases of equity securities by the issuer and affiliated purchasers Purchases of equity securities by the issuer and affiliated purchasers 138
16F Change in registrant’s certifying accountant Not applicable
16G Corporate governance Corporate governance 139
16H Mine safety disclosure Not applicable
17 Financial statements Not applicable
18 Financial statements Nexa Resources S.A. Financial statements 185
19 Exhibits Exhibits 183

 

iv

 

 

Forward-Looking Statements

 

Forward-looking statements

 

This annual report includes statements that constitute estimates and forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, or Securities Act, and Section 21E of the Securities Exchange Act, as amended, or Exchange Act. The words “believe,” “will,” “may,” “may have,” “would,” “estimate,” “continues,” “anticipates,” “intends,” “plans,” “expects,” “budget,” “scheduled,” “forecasts” and similar words are intended to identify estimates and forward-looking statements. Estimates and forward-looking statements refer only to the date when they were made, and we do not undertake any obligation to update or revise any estimate or forward-looking statement due to new information, future events or otherwise, except as required by law. Estimates and forward-looking statements involve risks and uncertainties and do not guarantee future performance, as actual results or developments may be substantially different from the expectations described in the forward-looking statements.

 

These statements appear in a number of places in this report and include statements regarding our intent, belief or current expectations, and those of our officers and employees, with respect to, among other things: (i) our future financial or operating performance; (ii) our growth strategy; (iii) future trends that may affect our business and results of operations; (iv) the impact of competition and applicable laws and regulations on our results; (v) planned capital investments; (vi) future of zinc or other metal prices; (vii) estimation of mineral reserves; (viii) mine life; and (ix) our financial liquidity.

 

Forward-looking statements are not guarantees of future performance and involve risks and uncertainties. Actual results and developments may be substantially different from the expectations described in the forward-looking statements for a number of reasons, many of which are not under our control, among them the activities of our competition, the future global economic situation, weather conditions, market conditions, exchange rates, and operational and financial risks. The unexpected occurrence of one or more of the abovementioned events may significantly change the results of our operations on which we have based our estimates and forward-looking statements. Our estimates and forward-looking statements may be influenced by the following factors, including, among others:

 

· the cyclical and volatile prices of commodities;

 

· the changes in the expected level of supply and demand for commodities;

 

· the risks and uncertainties relating to economic and political conditions in the countries in which we operate;

 

· changes in global market conditions;

 

· outbreaks of contagious diseases or health crises impacting overall economic activity regionally or globally;

 

· the duration and scope of, and uncertainties associated with, the coronavirus (“COVID-19”) pandemic and the impact thereof on commodity prices, our business and the global economy and any related actions taken by government and businesses in response to the COVID-19 pandemic, as well as our ability to contain and mitigate the risk of spread or major outbreak of COVID-19 at our operating sites;

 

· severe natural disasters, such as, storms and earthquakes, disrupting our operations;

 

· operational risks, such as operator errors, mechanical failures and other accidents;

 

· the availability of materials, supplies, insurance coverage, equipment, required permits or approvals and financing;

 

· the implementation of our growth strategy, the availability of capital and the risks associated with related capital expenditures;

 

· failure to obtain financial assurance to meet closure and remediation obligations;

 

1

 

 

Forward-Looking Statements

 

· the possible material differences between our estimates of mineral reserves and mineral resources and the mineral quantities we actually recover;

 

· the possibility that our concessions may be terminated or not renewed by governmental authorities in the countries in which we operate;

 

· labor disputes or disagreements with local communities, including the protest activities at our Atacocha operations in Peru, which, as of the date of this report, have led to the temporary suspension of our operations at the San Gerardo open pit mine;

 

· loss of reputation due to unanticipated operational failures or significant occupational incidents;

 

· the future impact of competition and changes in domestic and international governmental and regulatory policies that apply to our operations; and

 

· other factors discussed under “Risk Factors.”

 

In light of the risks and uncertainties described above, the events referred to in the estimates and forward-looking statements included in this report may or may not occur, and our business performance and results of operation may differ materially from those expressed in our estimates and forward-looking statements, due to factors that include but are not limited to those mentioned above.

 

These forward-looking statements are made as of the date of this report, and we assume no obligation to update them or revise them to reflect new events or circumstances. There can be no assurance that the forward-looking statements will prove to be accurate, as actual results and future events could differ materially from those anticipated in such statements.

 

2

 

 

Presentation of Financial and Other Information

 

About the Company

 

We are a large-scale, low-cost, integrated zinc producer with over 60 years of experience developing and operating mining and smelting assets in Latin America. We currently own and operate five long-life underground polymetallic mines—three located in the Central Andes of Peru and two located in the state of Minas Gerais in Brazil—and are developing the Aripuanã Project as our sixth underground mine in Mato Grosso, Brazil.

 

Nexa Resources S.A. is a public limited liability company (société anonyme) incorporated under the laws of Luxembourg on February 26, 2014. Our registered office is located at 37A, Avenue J.F. Kennedy, L-1855, Luxembourg, Grand Duchy of Luxembourg, and we are registered with the Luxembourg Trade and Companies Register under number B185489. Our telephone number at this address is +352 28 26 37 27. Our main office outside of Luxembourg is located at Avenida Engenheiro Luís Carlos Berrini, n° 105, 6th floor, São Paulo, State of São Paulo, Brazil. Our website is www.nexaresources.com. None of the information available on our website is incorporated in this annual report and it should not be relied upon in deciding to invest in our common shares.

 

3

 

 

Presentation of Financial and Other Information

 

Presentation of financial and other information

 

Certain definitions

 

Unless otherwise indicated or the context otherwise requires, the terms below are defined in the following manner.

 

· “Nexa,” “we,” “us” and “our” or similar terms refer to Nexa Resources and, unless the context otherwise requires, its consolidated subsidiaries;

 

· “Nexa Resources” refers to Nexa Resources S.A., a Luxembourg public limited liability company (société anonyme);

 

· “Nexa CJM” refers to our subsidiary Nexa Resources Cajamarquilla S.A. (previously known as Votorantim Metais—Cajamarquilla S.A.), a corporation organized as a sociedad anónima under the laws of Peru;

 

· “Nexa Brazil” refers to our subsidiary Nexa Recursos Minerais S.A. (previously known as Votorantim Metais Zinco S.A.), a corporation organized as a sociedade anônima under the laws of Brazil;

 

· “Nexa Peru” refers to our subsidiary Nexa Resources Peru S.A.A. (previously known as Compañía Minera Milpo S.A.A.), a corporation organized as a sociedad anónima abierta under the laws of Peru and publicly traded on the Lima Stock Exchange;

 

· “Enercan” refers to our subsidiary Campos Novos Energia S.A., a corporation organized as a sociedade anônima under the laws of Brazil;

 

· “VSA” refers to our controlling shareholder Votorantim S.A., a corporation organized as a sociedade anônima under the laws of Brazil;

 

· the “Votorantim Group” refers to our controlling shareholder VSA and, unless the context otherwise requires, its consolidated subsidiaries;

 

· the “real,” “reais” or “R$” refers to the Brazilian real, the official currency of Brazil;

 

· sol,” “soles” or “S/.” refers to the Peruvian sol, the official currency of Peru; and

 

In addition, the meaning of other defined terms used in this report are set out in “Glossary.”

 

Financial information

 

Our consolidated financial statements as of December 31, 2020 and 2019 and for each of the years ended December 31, 2020, 2019 and 2018 are included in this annual report. Our consolidated financial statements are prepared in accordance with International Financial Reporting Standards (“IFRS”) as issued by the International Accounting Standards Board (“IASB”). References in this report to “our consolidated financial statements” are to our consolidated financial statements as of December 31, 2020 and 2019 and for each of the years ended December 31, 2020, 2019 and 2018, and the related notes thereto included elsewhere in this report.

 

The financial information presented in this report should be read in conjunction with our consolidated financial statements, including the related notes, and the section of this report titled “Operating and financial review and prospects.”

 

The main consolidated companies included in our consolidated financial statements are:

 

· Nexa CJM – a Peruvian company that is 99.99% directly and indirectly owned by Nexa Resources and is mainly engaged in smelting zinc contained in concentrate. Nexa CJM’s functional currency is the U.S. dollar.

 

4

 

 

Presentation of Financial and Other Information

 

· Nexa Peru – a Peruvian company that is 80.23% directly and indirectly owned by Nexa Resources and is mainly engaged in exploring, extracting, producing and trading zinc, copper and lead concentrates, extracted from its own three mining sites. Nexa Peru’s functional currency is the U.S. dollar. Nexa Peru is a public company with its shares listed on the Lima Stock Exchange.

 

· Nexa Brazil –a Brazilian company that is 100% owned by Nexa Resources and is mainly engaged in exploring, extracting and producing zinc, copper and lead concentrates, and smelting zinc contained in concentrate with operations in the state of Minas Gerais. Nexa Brazil’s functional currency is the real.

 

Non-IFRS measures

 

Our management uses non-IFRS measures such as Adjusted EBITDA and cash cost, among other measures, for internal planning and performance measurement purposes. We believe these measures provide useful information about the financial performance of our operations that facilitates period-to-period comparisons on a consistent basis. Management uses Adjusted EBITDA internally to evaluate our underlying operating performance for the reporting periods presented and to assist with the planning and forecasting of future operating results. Management believes that Adjusted EBITDA is a useful measure of our performance because it reflects our cash generation potential from our operational activities excluding impairment of non-current assets and other miscellaneous adjustments, if any, for the period. These measures should not be considered individually or as a substitute for net income or operating income, as indicators of operating performance, or as alternatives to cash flow as measures of liquidity. Additionally, our calculation of Adjusted EBITDA and other non-IFRS measures may be different from the calculation used by other companies, including our competitors in the mining industry, so our measures may not be comparable to those of other companies. See “Selected financial data” for a discussion of our use of non-IFRS measures in this report, including the reasons why we believe this information is useful to management and to investors, and a reconciliation to the comparable IFRS measures.

 

All forward-looking non-IFRS financial measures in this document, including cash cost guidance, are provided only on a non-IFRS basis. This is due to the inherent difficulty of forecasting the timing or number of items that would be included in the most directly comparable forward-looking IFRS financial measures. As a result, reconciliation of the forward-looking non-IFRS financial measures to IFRS financial measures is not available without unreasonable effort and we are unable to assess the probable significance of the unavailable information.

 

Country, market and industry information

 

This report contains and refers to information and statistics regarding the countries in which we operate and the markets for the metals we produce. This data is obtained from independent public sources, including publications and materials from participants in the industry, such as Wood Mackenzie and from governmental entities such as the Brazilian Central Bank, Bloomberg Finance L.P., London Metal Exchange (“LME”), London Bullion Market Association (“LBMA”), Brazilian Ministry of Treasury (Ministério da Fazenda), Brazilian Ministry of Mines and Energy (Ministério de Minas e Energia, or “MME”), National Mining Agency (Agência Nacional de Mineração, or “ANM”), B3 S.A. – Brasil, Bolsa, Balcão, Brazilian Institute of Geography and Statistics (Instituto Brasileiro de Geografia e Estatística, or “IBGE”), the Getulio Vargas Foundation (Fundação Getúlio Vargas, or “FGV”), the Peruvian Stock Market Superintendency (Superintendencia del Mercado de Valores), the Peruvian Central Bank, the Peruvian Ministry of Economy and Finance (Ministerio de Economía y Finanzas) and the Peruvian National Institute of Statistics and Informatics (Instituto Nacional de Estadística e Informática). Some data is also based on our estimates, which are derived from our review of internal reports, as well as independent sources.

 

Volume information

 

All tonnage information in this report is expressed in metric tonnes, unless stated otherwise, and all references to ounces are to troy ounces, in each case, unless otherwise specified.

 

5

 

 

 

Risk Factors

 

Risk factors

 

Nexa and its operations are exposed to a number of inherent risks and uncertainties, including those described below.

 

Business risks

 

Our business is highly dependent on the international market prices of the metals we produce, which are both cyclical and volatile.

 

Our business and financial performance is significantly affected by the market prices of the metals we produce, particularly the market prices of zinc, copper, silver, lead and, to a lesser extent, gold. Historically, prices of such metals have been subject to wide fluctuations and are affected by numerous factors beyond our control, including international economic and political conditions, the cyclicality of consumption, actual or perceived changes in levels of supply and demand, the availability and costs of substitutes, inventory levels maintained by users, actions of participants in the commodities markets and currency exchange rates. We cannot predict whether, and to what extent, metal prices will rise or fall in the future.

 

During 2020, the COVID-19 pandemic and resulting negative impact on the global economy exacerbated the cyclicality and volatility of international market prices in the metals we produce. Lockdown measures imposed during the first half of the year to combat the spread of the COVID-19 pandemic affected overall demand, which led to a decrease in prices, reduced production and inventory shortages. Metal prices and demand are expected to remain volatile as the COVID-19 pandemic continues to affect global macroeconomic conditions. See “Operating and Financial Review and Prospects—Key factors affecting our business and results of operations—Metal Prices” for additional information on the impact of volatility of metal prices on our business and financial condition.

 

Future declines in metal prices, whether related to the ongoing COVID-19 pandemic or otherwise, and especially with respect to zinc, copper, silver and lead prices, could have an adverse impact on our results of operations and financial position, and we might consider curtailing or modifying certain operations or not proceeding with our sustaining and/or growth strategy. In addition, we may not be able to adjust production volume in a timely or cost efficient manner in response to changes in metal prices. Lower utilization of capacity during periods of weak prices may expose us to higher unit production costs since a significant portion of our cost structure is fixed in the short-term due to the high capital intensity of mining operations. Conversely, during periods of high prices, our ability to rapidly increase production capacity may be limited, which could prevent us from selling more products. Moreover, we may be unable to complete expansions and greenfield projects in time to take advantage of rising prices for zinc, copper, lead or other products.

 

Changes in the demand for the metals we produce, including as a result of the cyclicality of global economic activity, could adversely affect our sales volume and revenues.

 

Our revenues depend on the volume of metals we sell (and, to a lesser extent, the volume of metals produced by others that are smelted in our facilities), which in turn depend on the level of industrial and consumer demand for these metals. An increase in the production of zinc, copper, silver and lead worldwide, along with a reduction in demand for these metals due to changes in technology, industrial processes or consumer habits, including increased demand for substitute materials, economic slow-downs or other factors, may have the potential to impact these metal prices. The impact of price decreases may also compromise the profitability of smelters, as we might consider reducing the volume of metals we sell and therefore materially adversely impact our operational results and financial position. Even if our volumes are not affected by reduced prices, this decrease can impact our revenues.

 

The mining industry has historically been highly volatile largely due to the cyclical nature of industrial production, which affects the demand for minerals and metals. Demand for minerals and metals thus generally correlates to macroeconomic fluctuations in the global economy. Changes in the demand for the metals we produce could adversely affect our sales volume and revenues.

 

6

 

 

Risk Factors

 

Adverse economic developments in China could have a negative impact on our revenues, cash flow and profitability.

 

China has been the main source of global demand for commodities over the last few years. According to Wood Mackenzie, in 2020, despite the overall effects of the COVID-19 pandemic, Chinese demand represented 53% of global demand for zinc and 54% of global demand for copper. Any slowdown in China’s economic growth that is not offset by increased demand or reduced supply from other regions could have an adverse effect on demand for our products or commodity prices and result in lower revenues, cash flow and profitability.

 

The mining industry is highly competitive.

 

We face competition from other mining, processing, trading and industrial companies in Brazil, Peru and around the world. Competition principally involves the following factors: sales, supply and labor prices; contractual terms and conditions; attracting and retaining qualified personnel; and securing the services, supplies and technologies we need for our operations. Slower development in technology and innovation could impact costs, productivity and competitiveness. In addition, mines have limited lives and, as a result, we must seek to replace and expand our mineral reserves by acquiring new properties. Significant competition exists to acquire mining concessions, land and related assets. We cannot assure shareholders that competition will not adversely affect us in the future.

 

The international trade environment faces increasing uncertainty. Potential changes to international trade regulations and agreements, as well as other political and economic arrangements (including direct or indirect subsidies), may benefit competitors operating in countries other than where our mining operations are currently located. These changes could also adversely affect the prices we pay for the supplies we need and our export costs when we engage in international transactions. We cannot assure shareholders that we will be able to compete based on price or other factors with companies that in the future may benefit from favorable regulations, lower cost of capital, trading or other arrangements or that we will be able to maintain the cost of the supplies that we require as well as our export costs.

 

Operational risks

 

The mining business is subject to inherent risks, some of which are not insurable.

 

The business of mining zinc, copper, silver, lead and other minerals is generally subject to numerous risks and hazards. Hazards associated with underground mining operations include underground fires and explosions, including those caused by flammable gas, gas and coal outbursts, cave-ins or falls of ground, rock falls, openings collapse, lack of oxygen, air pollution, tailings dam failures or other discharges of tailings, hazardous substances and materials, gases and toxic chemicals, water ingress and flooding, sinkhole formation, ground subsidence, and other accidents and conditions resulting from underground mining activities, such as drilling, blasting, removing and processing material. In addition, we may encounter geotechnical challenges as we continue with and expand our mining activities, including the possibility of failure of underground openings. For example, see “Mining Operations—Vazante—Operations and infrastructure”. We could incur additional expenses in connection with preventive and remediating measures related to underground openings, which could materially adversely affect results of our operations and financial position.

 

Such occurrences could result in damage to, or destruction of, our properties or production facilities, third-party property, human exposure to pollution, personal injury or death, environmental and natural resource damage or contamination, delays in mining, monetary losses and legal liability. In addition, any such occurrences could adversely affect our reputation. Damages to our reputation could result in additional environmental and health and safety legal oversight, and authorities could impose more stringent conditions in connection with the licensing process of our projects and operations. In addition, our customers may be less willing to buy metals from us if we have been subject to significant adverse publicity. We maintain insurance typical in the mining industry, and in amounts that we believe to be adequate, but which may not provide complete coverage in certain circumstances. Insurance against certain risks (including certain liabilities for environmental contamination, tailings dam failures and other hazards as a result of exploration and production) may not be generally available or is uneconomical to afford. We could also incur additional expenses due to failures in our industrial drainage system or other environmental control equipment.

 

7

 

 

Risk Factors

 

We may be materially adversely affected by challenges relating to slope and stability of underground openings.

 

Our underground mines get deeper and our waste and tailings deposits increase in size as we continue with and expand our mining activities. This presents certain geotechnical challenges, including the possibility of failure of underground openings. If we are required to reinforce such openings or take additional actions to prevent such a failure, we could incur additional expenses, and our operations and stated mineral reserves could be negatively affected. We have taken actions we consider appropriate to maintain the stability of underground openings, but additional actions may be required in the future. Unexpected failures or additional requirements to prevent such failures may materially adversely affect our costs and expose us to health, safety and other liabilities in the event of an accident. These developments may in turn materially adversely affect the results of our operations and financial position, as well as potentially diminish our stated mineral reserves.

 

Our projects are subject to operational risks that may result in increased costs or delays that prevent their successful implementation.

 

We invest in sustaining and increasing our mine and metal production capacity and developing new operations. Our projects are subject to several risks that may materially adversely affect our growth prospects and profitability, including the following:

 

· we may encounter delays or higher than expected costs in completing technical and engineering studies and obtaining the necessary equipment, machinery, materials, supplies, labor or services, in project execution by third-party contractors and in implementing new technologies to develop and operate a project;

 

· we may experience delays in commencing the operations of a new project or the expansion of an existing operation;

 

· our efforts to develop projects according to schedule may be hampered by a lack of infrastructure, including a reliable power supply;

 

· we may fail to obtain, or experience delays or higher than expected costs in obtaining, the required agreements, authorizations, licenses, approvals and permits to develop a project, including the prior consultation procedure and agreements with local communities;

 

· changes in market conditions or regulations may make a project less profitable than expected at the time we initiated work on it;

 

· accidents, natural disasters, labor disputes and equipment failures;

 

· adverse mining conditions may delay and hamper our ability to produce the expected quantities and qualities of minerals upon which the project was budgeted;

 

· mineral reserves and resources are estimates based on the interpretation of limited sampling data and test work that may not be representative of the deposits as a whole, or the technical and economic assumptions used in the estimates may prove to be materially different when the deposits are mined, that could result in materially different economic outcomes; and

 

· conflicts with local communities and/or strikes or other labor disputes may delay the implementation or the development of projects.

 

We may be adversely affected by the failure or unavailability of adequate infrastructure and skilled labor.

 

Our mining, smelting, processing, development and exploration activities depend to a large degree on adequate infrastructure. The regions where certain of our current operations, projects and prospects are located are sparsely populated and difficult to access. We require reliable roads, bridges, power sources and water supplies to access and properly conduct our operations. As a result, the availability and cost of this infrastructure affects capital and operating costs and our ability to maintain expected levels of production and sales. We could also experience an increase in transit-related accidents due to the need to transport employees to remote areas. Unusual weather, such as excessive rains and flooding, or other natural phenomena, sabotage, government or external interference in the maintenance or provision of such infrastructure could impact the development of a project, reduce mining volumes, increase mining or exploration costs or delay the transportation of raw materials to the mines and projects or concentrates to the customers. See “Risk factors—Health, safety and environmental risks—Natural disasters and climate change could affect our business.”

 

In addition, the mining industry is labor intensive, and our success depends to a significant extent on our ability and our contractors’ ability to attract, hire, train and retain qualified employees, including our ability and our contractors’ ability to attract employees with the necessary skills in the regions in which we operate. We could experience increases in our recruiting and training costs and decreases in our operating efficiency, productivity and profit margins if we are unable to attract, hire and retain a sufficient number of skilled employees to support our operations.

 

8

 

 

Risk Factors

 

The failure of a tailings dam could negatively impact our business, reputation and results of operations, and the implementation of associated regulations and decommissioning processes may be expensive.

 

Mining companies face inherent risks in their operations of tailings dams—structures built for the containment of the mining waste, known as tailings—that exposes us to certain risks. Our tailings dams include, in some cases, materials that could increase the hazard potential in the event of unexpected failure. If any such risks were to occur, this could materially adversely affect our reputation and our ability to conduct our operations and could make us subject to liability and, as a result, have a material adverse effect on our business, financial position and results of operations.

 

In addition, the changes in regulation that may occur as a result of recent dam failures, like those that have occurred in Brazil, could increase the time and costs to build, operate, inspect, maintain and decommission tailings dams, obtain new licenses or renew existing licenses to build or expand tailings dams, or require the use of new technologies. New regulations, such as those enacted in Brazil during 2020, may also impose more restrictive requirements that may exceed our current standards, including mandated compliance with emergency plans and increased insurance requirements, or require us to pay additional fees or royalties to operate tailings dams. We may also be required to provide for and facilitate the relocation of communities and facilities impacted by tailings dam failures. Moreover, insurance coverage for damages resulting from tailings dams’ failure may not be available. For more information see “Information on the Company—Mining operations—Tailings disposal.”

 

A disruption in zinc concentrate supply could have a material adverse effect on our production levels and financial results.

 

A portion of the zinc concentrate used by our smelters is obtained from third parties, and we may be adversely affected if we are not able to source adequate supplies of zinc for such operations. In 2020, 46.4% of the zinc concentrate used by our smelters was obtained from third parties, with the remainder supplied by our own mining operations. The availability and price of zinc concentrate used by our smelters may be negatively affected by several factors largely beyond our control, including interruptions in production in our mines or by our suppliers, decisions by suppliers to allocate supplies of concentrate to other purchasers, price fluctuations and increasing transport cost. In addition, the efficiency of a smelter’s production over time is affected by the mix of the zinc concentrate qualities it processes. In circumstances where we cannot source adequate supplies of the zinc concentrate qualities that comprise the most efficient mix for our smelters, alternative types of concentrate may be available, but the use thereof may increase our costs of production or reduce the productivity of our smelters and adversely affect our business, results of operations and financial position.

 

Inadequate supply of zinc secondary feed materials and zinc calcine could affect the results of our smelters.

 

Zinc sourced from suppliers of secondary feed materials represented approximately 17.6% of the zinc content used by our Juiz de Fora smelter in 2020. The use of zinc secondary feed material is a competitive advantage in relation to the use of zinc concentrate, mainly due to lower acquisition costs and, to a lesser extent, operational gains. In addition, we have recently incorporated zinc calcine processed by third parties into our operations to increase the production in our smelters. Our smelters then use this zinc calcine processed by third parties to produce additional refined zinc products that they would not produce were they to rely solely on other inputs. To the extent we are unable to obtain adequate supplies of zinc secondary feeds or zinc calcine, or if we must pay higher than anticipated prices of these inputs, our business, results of operations and financial position may be adversely affected.

 

Interruptions of energy supply or increases in energy costs may materially adversely affect our operations.

 

Energy is an important component of our production costs. In Peru, we obtain electric power for our operations from third parties through electricity supply contracts. Although we have recently entered into a long-term power purchase agreement with Electroperú S.A., we cannot assure you that we will have secure access to energy sources in Peru at the same prices and conditions in the event of any interruption or failure of our sources of electricity, failures or congestion in any part of the Sistema Eléctrico Interconectado Nacional (“SEIN”) or any failure to renew or extend our other existing electricity supply contracts.

 

In Brazil, we obtain electric power for our operations from hydroelectric plants grouped into several legal entities—which are directly or indirectly jointly owned by us, our controlling shareholder and its affiliates—pursuant to long-term power purchase agreements. Although these hydroelectric plants currently provide 89.4% of our estimated consumption of electricity, any unavailability or shortages of electrical power or other energy sources and interruptions of energy supply may have a material adverse impact on our results of operations. Furthermore, our energy costs under these agreements could increase in the event of differences in the hydrology forecast due to these hydroelectric plants paying additional levies. For more information, see “Information on the Company—Other operations—Power and energy supply.”

 

The prices for and availability of energy resources for our operations may be subject to change or curtailment due to, among other things, new laws or regulations, the imposition of new taxes or tariffs, supply interruptions, equipment damage, worldwide price levels, market conditions and any inability to renew our existing supply contracts. Disruptions in energy supply or increases in costs of energy resources could have a material adverse effect on our financial position and results of operations.

 

9

 

 

Risk Factors

 

Shortages of water supply, explosives, critical spare parts, maintenance service and new equipment and machinery may materially adversely affect our operations and development projects.

 

Our mining operations require the use of significant quantities of water for extraction activities, processing and related auxiliary facilities. Water usage, including extraction, containment, and recycling requires appropriate permits, which are granted by regulatory authorities in Brazil and Peru. The available water supply may be adversely affected by shortages or changes in governmental regulations. We cannot assure shareholders that water will be available in sufficient quantities to meet our future production needs or will prove sufficient to meet our water supply needs. In addition, we cannot assure shareholders that we will maintain our existing licenses related to water rights. A reduction in our water supply could materially adversely affect our business, results of operations and financial position. In addition, we have not yet obtained the water rights to support some of our expansion projects, and our inability to obtain those rights could prevent us from pursuing those expansions.

 

In addition to water, our mining operations require intensive use of equipment and machinery as well as explosives. To be able to acquire and use explosives, we must first obtain the corresponding authorizations, which are granted by the relevant regulatory authorities in Brazil and Peru. A shortage in the supply of key spare parts, adequate maintenance service, new equipment and machinery to replace old ones and cover expansion requirements, or explosives, including due to the inability to deliver such water, energy, supplies, critical spare parts, explosives, or equipment and machinery to our operations, could materially adversely affect our operations and development projects.

 

We may be adversely affected by labor disputes.

 

Mining is a labor intensive industry. We depend on more than 12,000 workers, including employees and contractors, to carry out our operations. A portion of our employees are unionized. We cannot assure that we will not experience work slowdowns, work stoppages, strikes or other labor disputes in the future, particularly in the context of the annual renegotiation of our collective bargaining agreements.

 

We may also be affected by labor-related disputes that broadly develop in the countries in which we operate. Strikes and other labor disruptions at any of our operations could have a material adverse effect on our business, financial position and results of operations.

 

We may be liable for certain payments to individuals employed by third-party contractors.

 

Under Peruvian law, outsourcing of employees from third-party contractors is permitted if certain requirements are met. To the extent that such requirements are not met, we may be jointly liable for all mandatory employment benefits and may be required to pay workers used under an outsourcing scheme with profit-sharing benefits as if they were employed directly by us. Moreover, we may be required to consider such persons employed by third-party contractors as our employees. Although we believe that we are in material compliance with Peruvian labor laws, we cannot assure shareholders that any proceedings initiated by outsourced employees will be resolved in our favor and that we will not be liable for any mandatory employment benefits or for profit sharing benefits. See “Information on the Company—Regulatory matters—Peruvian regulatory framework.”

 

Under Brazilian law, outsourcing is also permitted if certain requirements are met. In addition, Brazilian law provides that the contractor will be held liable on a secondary basis if the outsourced or subcontracted companies do not fulfill their labor obligations. In cases where the outsourced or subcontracted companies do not pay the workers the labor sums they are entitled to, the contractor is responsible for those payments. These payments may have an adverse effect on our results of operation and financial position. Recent changes to Brazilian labor laws have affected outsourcing, and we cannot predict how these changes will be further regulated and applied by local authorities and interpreted by Brazilian labor courts. If outsourcing becomes more restrictive or costly because of these new laws, our cash flow may be reduced, affecting our financial position and results of operations. See “Information on the Company—Regulatory matters—Brazilian regulatory framework.”

 

10

 

 

Risk Factors

 

We may be subject to misconduct by our employees or third-party contractors.

 

We may be subject to misconduct by our employees or third-party contractors, such as theft, bribery, sabotage, fraud, insider trading, violation of laws, slander or other illegal actions. Any such misconduct may lead to fines or other penalties, slow-downs in production, increased costs, lost revenues, increased liabilities to third parties, impairment of assets or harmed reputation, any of which may have a material adverse effect on our business, results of operations or financial position.

 

The nature of our business includes risks related to litigation and administrative proceedings that could materially adversely affect our business and financial performance in the event of unfavorable rulings.

 

The nature of our business exposes us to various litigation matters, including civil liability claims, environmental matters, health and safety matters, regulatory and administrative proceedings, governmental investigations, tort claims, contract disputes, labor matters and tax matters, among others. We cannot assure shareholders that these or other legal proceedings will not have a material adverse effect on our ability to conduct our business or on our financial position and results of operations, through distraction of our management team, diversion of resources or otherwise. In addition, although we establish provisions as we deem necessary in accordance with IFRS as issued by the IASB, the level of provisions that we record could vary significantly from any amounts we actually pay, due to the inherent uncertainties in the estimation process.

 

We could be harmed by a failure or interruption of our information technology systems or automated machinery, including system security breaches or other cybersecurity attacks.

 

We rely on our information technology systems and automated machinery to effectively manage our production processes and operate our business. Any failure of our information technology systems and automated machinery to perform as we anticipate could disrupt our business and result in production errors, processing inefficiencies and the loss of sales and customers, which in turn could result in decreased revenue, increased overhead costs and excess or out-of-stock inventory levels resulting in a material adverse effect on our business results.

 

In recent years, cyberattacks and other tactics designed to gain access to and exploit sensitive information by breaching mission critical systems of large organizations have increased in volume and sophistication. We are dependent on internal information, and we are vulnerable to failure of these systems, including through system security breaches, data protection breaches or other cybersecurity attacks. We could be exposed to a cyberattack through an internal breach from servers connected to our internal network or an external breach due to disruptions from unauthorized access to our systems, which could impact our ability to operate our existing systems. If these events occur, including a cyberattack causing critical data loss or the disclosure or use of confidential information, the exposure of such information could have a material adverse effect on our reputation and market value, which could adversely impact our results of operations.

 

In addition, data privacy is subject to frequently changing rules and regulations. The European Union’s General Data Protection Regulation, or GDPR, took effect in 2018 and introduced increased regulations relating to personal data security. The GDPR requires companies to satisfy new requirements regarding the handling of personal and sensitive data, including its use, protection and the ability of persons whose data is stored to correct or delete such data about themselves. In 2018, the Brazilian president signed Law No. 13,709, the Lei Geral de Proteção de Dados (“LGPD”), a comprehensive data protection law. The LGPD establishes detailed rules for the collection, use, processing and storage of personal data and is expected to affect all economic sectors, including the relationship between customers and suppliers of goods and services, employees and employers and other relationships in which personal data is collected, whether in a digital or physical environment. The LGPD took effect in September 2020. Any noncompliance with the GDPR, the LGPD or any other cybersecurity and data privacy regulations could result in proceedings or actions against us by governmental entities, the imposition of fines or penalties and damage to our reputation, which could have an adverse effect on us and our business, reputation and results of operations.

 

11

 

 

Risk Factors

 

Financial risks

 

Our financial position and results of operations may be materially adversely affected by currency exchange rate fluctuations.

 

Our revenues are primarily denominated in U.S. dollars, and certain portions of our operating costs, principally labor costs, are denominated in reais and soles. Accordingly, when inflation in Brazil and Peru increases without a corresponding devaluation of the real or sol, our financial position, results of operations and cash flows could be materially adversely affected. See “Operating and Financial Review and Prospects—Key factors affecting our business and results of operations—Macroeconomic conditions of the countries and regions where we operate” for a discussion of inflation in 2020.

 

Given the structure of our operations, a decrease in the value of the U.S. dollar relative to the foreign currencies in which we incur costs generally could have a negative impact on our results of operations or financial position. Our foreign currency exposures increase the risk of volatility in our financial position, results of operations and cash flows. We cannot assure shareholders that currency fluctuations, or costs associated with our hedging activities (including fluctuations in exchange rates contrary to our expectations), will not have an impact on our financial position and results of operations.

 

Fluctuations in interest rates could increase the cost of servicing our debt, affect returns on our financial investments and negatively affect our overall financial performance.

 

Some of our indebtedness bears interest based on variable interest rates, including the London Interbank Offered Rate, or LIBOR. As of December 31, 2020, 28.1% of our debt was variable rate debt. Such variable rates have fluctuated in response to changes in economic growth, monetary policy and governmental regulation. A significant increase in underlying interest rates, particularly in LIBOR, could have a material adverse effect on our financial expenses and materially adversely affect our overall financial performance. In July 2017, the Financial Conduct Authority (“FCA”) announced its intention to phase out LIBOR by the end of 2021. However, on March 5 2021, the FCA announced that most tenors of U.S. Dollar LIBOR would continue to be published through June 30, 2023, extending the previously announced deadline of December 2021.

 

The Company is discussing with the financial entities which fallback rate will replace the interest rate for our relevant LIBOR-based debt, and given the extension of most U.S. Dollar LIBOR tenors until June 30, 2023, we do not expect any relevant impacts on our business, financial position and results of operations in the current year.

 

We may engage in hedging activity which may not be successful and may result in losses to us.

 

We may use foreign exchange and metal commodity non-deliverable forwards to reduce the risk associated with currency and metal price volatility. However, our hedging activities could cause us to lose the benefit of an increase in the prices of the metals we produce if they increase over the price level of hedge positions, or the benefit of an increase in the currency price. The cash flows and the mark-to-market values of our production hedges can be affected by factors such as the volatility of currency and the market price of metals, which are not under our control.

 

Our hedging agreements contain events of default and termination events that could lead to early close-outs of our hedges such as failure to pay, breach of the agreement, misrepresentation, default under our loans or other hedging agreements and bankruptcy. In the event of an early termination of our hedging agreements, the relevant hedge positions would be required to be settled at that time. In that event, there could be a lump sum payment to be made either to or by us. The magnitude and direction of such a payment would depend upon, among other things, the characteristics of the particular hedge instruments that were terminated and the relevant market prices at the time of termination. Any of the factors described above could have a material adverse effect on our financial position, results of operations or cash flows. See “Operating and financial review and prospects—Risk management—Financial risk—Metal price sensitivity.”

 

12

 

 

Risk Factors

 

Our business requires substantial capital expenditures and is subject to financing risks.

 

Our business is capital intensive. Exploration for and exploitation of mineral deposits, maintenance of machinery and equipment and compliance with applicable laws and regulations require substantial capital expenditures. We must continue to invest capital to maintain and potentially expand our existing brownfield operations, develop our greenfield projects pipeline in order to sustain and grow production, in addition to carrying out investments in sustaining, health, safety and environment. In 2020, we invested US$336.5 million in capital expenditures, US$186.7 million of which was in relation to the Aripuanã project. We depend partially on our cash flows for maintenance of capital expenditures. See “Information on the Company—Capital expenditures.”

 

No assurance can be given that we will be able to maintain our production levels or generate sufficient cash flow, capitalize on a sufficient amount of our net income or have access to sufficient investments, loans or other financing alternatives to finance our capital expenditure program at a level necessary to sustain and grow our current exploration and exploitation activities. Any equity or debt financing, if available, may not be on terms that are favorable to us. If our access to external financing is limited, we may not be able to execute our strategy, which could adversely affect our business, financial position and results of operations.

 

We are exposed to credit risk in relation to our contractual and trading counterparties as well as to hedging and derivative counterparty risk.

 

We are subject to the risk that the counterparties with whom we conduct our business (in particular our customers) and who are required to make payments to us are unable to make such payment in a timely manner or at all. Credit risk is present in our hedging operations, customer operations and cash management operations. If amounts that are due to us are not paid or not paid in a timely manner, this may impact not only our current trading and cash-flow position but also our financial and business position. In addition, our derivatives, metals hedging, and foreign currency and energy risk management activities expose us to the risk of default by the counterparties to such arrangements. Any such default could have a material adverse effect on our business, financial position and results of operations.

 

Any acquisitions we make may not be successful or achieve the expected benefits.

 

We regularly consider and evaluate opportunities to acquire assets, companies and operations. There can be no assurance that we will be able to successfully integrate any acquired assets, companies or operations. In addition, any additional debt we incur to finance an acquisition may materially adversely affect our financial position and results of operations. If future acquisitions are significant, they could change the scale of our business and expose us to new geographic, political, operating and financial risks.

 

Changes in the assumptions underlying the carrying amount of certain assets could result in impairment charges.

 

We periodically test whether our tangible and intangible assets have suffered any impairment, in accordance with the accounting policy stated in our consolidated financial statements. If our estimates of the recoverable amount of an asset change or are inaccurate, we may determine that impairment charges are necessary. While impairment does not affect reported cash flows, the decrease in the recoverable amount determined could have a material adverse effect on our results of operations. Assurances cannot be given as to the absence of significant impairment charges in future periods, particularly if market conditions deteriorate.

 

13

 

 

Risk Factors

 

Risks related to our mineral reserves and resources

 

Our estimates of mineral reserves and resources may be materially different from the total mineral quantities we actually recover, and changes in metal prices, operating and capital costs, and other assumptions used to calculate these estimates may render certain mineral reserves and resources uneconomical to mine.

 

There is a degree of uncertainty attributable to the estimation of mineral reserves and resources. Until mineral reserves and resources are actually mined and processed, the quantity of metal and grades must be considered as estimates only and no assurance can be given that the indicated levels of metals will be produced. In making determinations about whether to advance any of our projects to development, we must rely upon estimated calculations for the mineral reserves and mineral resources and grades of mineralization on our properties.

 

The estimation of mineral reserves and resources is a subjective process that is partially dependent upon the judgment of the qualified persons preparing such estimates. The process relies on the quantity and quality of available data and is based on knowledge, mining experience, statistical analysis of drilling results and industry practices. Valid estimates made at a given time may significantly change when new information becomes available.

 

Our estimates of mineral reserves and resources are based on geological interpretation and statistical inferences or assumptions drawn from drilling and sampling analysis made as of the date of such estimates. We periodically update our mineral reserves and resources estimates based on the conclusions of the relevant qualified persons with respect to new data from exploratory and infill drilling, results from technical studies and the experience acquired during the operation of the mine and metallurgical processing, as well as changes to the assumptions used to calculate these estimates.

 

Several of the assumptions used to calculate these estimates, including the market prices of commodities, operating and capital costs and mining and metallurgical recovery rates, among others, can greatly fluctuate, which may result in significant changes to our current estimates. These changes may also render some or all of our proven and probable mineral reserves and measured and indicated mineral resources uneconomic to exploit and may ultimately result in a reduction of mineral reserves and resources.

 

In addition, inferred mineral resources have a great amount of uncertainty as to their existence and their economic and legal feasibility. You should not assume that any part of an inferred mineral resource will be upgraded to a higher category or that any of the mineral resources not already classified as mineral reserves will be reclassified as mineral reserves.

 

We depend on our ability to replenish our mineral reserves for our long-term viability.

 

Mineral reserves data is only indicative of future results of operations at the time the estimates are prepared and are depleted over time as we conduct our mining operations. We use several strategies to replenish and increase our mineral reserves that are depleted, including exploration activities and the acquisition of mining concessions. If we are unable to replenish our mineral reserves or develop our mineral resources, our business, results of operations and prospects would be materially adversely affected.

 

14

 

 

Risk Factors

 

Our mineral exploration efforts are highly speculative in nature and may be unsuccessful.

 

Mineral exploration is highly speculative in nature, involves many uncertainties and risks and may be unsuccessful. It is performed to demonstrate the dimensions, position and mineral characteristics of mineral deposits, estimate mineral reserves and resources, assess amenability of the deposit to mining and processing scenarios and estimate potential deposit value.

 

Substantial expenditures are required to establish proven and probable mineral reserves, to determine processes to extract the metals and, if required, to construct mining and processing facilities and obtain permits to carry on mining activities. Therefore, once the mineralization is discovered, it may take several years from the initial exploration phases and mineral resources determination before production is possible, during which time the project’s feasibility may change adversely.

 

Health, safety and environmental risks

 

Health, safety and environmental laws and regulations, including regulations pertaining to climate change, may increase our costs of doing business, restrict our operations or result in the imposition of fines or revocation of permits.

 

Our mining activities are subject to Brazilian and Peruvian laws and regulations, including health and safety and environmental matters. Additional matters subject to legislation include, but are not limited to, transportation, mineral storage, water use and discharge, use of explosives, hazardous and other non-hazardous waste, and reclamation and remediation measures. Our operations are subject to periodic inspections and special inspections in certain circumstances by governmental authorities and consultation with local communities. Compliance with these laws and regulations and new or existing regulations that may be applicable to us in the future could increase our operating costs and adversely affect our financial results of operations and cash flows.

 

Regulatory and industry response to climate change or other controls on greenhouse gas emissions, including limits on emissions from the combustion of carbon-based fuels, controls on effluents and restrictions on the use of certain materials, could significantly increase our operating costs and affect our customers. Ongoing international efforts to address greenhouse gas emissions consist of controlling activities that may increase the atmospheric concentration of greenhouse gases. International agreements, like the Paris Agreement and Kyoto Protocol, are in different stages of negotiation and implementation. The measures included in such agreements may result in an increase of costs related to the installation of new controls aimed at reducing greenhouse gas emissions, the purchase of credits or licenses for atmospheric emissions and the monitoring and registration of greenhouse gas emissions generated by our operations. These measures could adversely affect our business, financial position and results of operations. The potential impact of climate change on our operations is highly uncertain and would be particular to the geographic circumstances of our facilities and operations. It may include changes in rainfall patterns, water shortages, rising sea levels, changing storm patterns and intensities and changing temperatures. These effects may materially adversely impact the cost, production and financial performance of our operations.

 

Pursuant to applicable environmental regulations and laws, we could be found liable for all or substantially all the damages caused by mining activities at our current or former facilities or those of our predecessors at disposal sites. We could also be found liable for all incidental damages due to the exposure of individuals to hazardous substances or other environmental damage. We cannot assure shareholders that our costs of complying with current and future environmental and health and safety laws and regulations, including decommissioning and remediation requirements, and any liabilities arising from past or future releases of, or exposure to, hazardous substances will not materially adversely affect our business, financial position and results of operations.

 

Natural disasters and climate change could affect our business.

 

Natural disasters could significantly damage our mining and production facilities and infrastructure and may cause a contraction in sales to countries adversely affected due to, among other factors, power outages and the destruction of industrial facilities and infrastructure. In particular, the Central Andean region, where two of our mines are located, is prone to mudslides and earthquakes of varying magnitudes. Due to the El Niño weather phenomenon, Peru typically experiences extreme weather conditions that led to flooding and mudslides and which could adversely affect our operations. In the past, extreme flooding and mudslides in Peru have interrupted the supply of metal concentrates from our mines and the supply of zinc products to our plants. The physical impact of climate change on our business remains uncertain, but we are likely to experience changes in rainfall patterns, increased temperatures, water shortages, rising sea levels, lower water levels in rivers due to natural or operational conditions, increased storm frequency and intensity as a result of climate change, which may adversely affect our operations. Although we have insurance covering damages caused by natural disasters, extensive damage to our facilities and staff casualties due to natural disasters could materially adversely affect our ability to conduct our operations and, as a result, reduce our future operating results.

 

15

 

 

Risk Factors

 

Global or regional health considerations, including the outbreak of a pandemic or contagious disease, such as the ongoing COVID-19 pandemic, have had and could continue to have adverse effects on our business, financial condition and results of operations.

 

The ongoing COVID-19 pandemic, including governmental measures enacted in response to the pandemic, has had and continues to have a negative effect on the global economy, disrupting the financial markets and creating increased volatility which has resulted in disruptions to our operations and affected our financial results. The COVID-19 pandemic has affected our workforce health and safety, reduced our operational capacity and disrupted transportation networks and supply chains. While international prices for some of our metals increased during the second half of 2020 and demand for our products has recovered, our production and results may continue to be affected by the increased volatility in metal prices and its impact on demand. See “—Our business, results and financial position are highly dependent on the demand for an international market prices of the metals we produce, which are both cyclical and volatile” and “—Changes in the demand for the metal we produce could adversely affect our sales volume and revenues.” Government authorities in the countries in which we operate, and in particular in Peru, implemented policies in response to the COVID-19 pandemic that negatively affected our financial position, results of operations and cash flows, particularly during the second quarter of 2020. On March 15, 2020, the Peruvian government declared a state of emergency in response to COVID-19, imposing operating restrictions on non-essential industries, which included the mining sector. The restriction period was continuously extended until mid-May, 2020 affecting our operations in the country. For more information on the impact of the COVID-19 pandemic on Nexa’s operations, see “Operating and Financial Review and Prospects—Overview—Executive Summary” and “Operating and Financial Review and Prospects—Overview—Key factors affecting our business and results of operations—COVID-19.”

 

The COVID-19 pandemic and the response thereto continue to evolve. In Peru, a second lockdown to address the “second-wave” was imposed in early 2021, although our Peruvian operations have not been impacted by these additional measures to date. We cannot at this time forecast what policies will be implemented by governments to continue to address the pandemic, or the pandemic’s ultimate duration, severity or impact to our business, our customers or our supply chain. This negative impact could continue for an extended period of time or more severely impact our financial condition and results of operations, and continued weak or worsening economic conditions could negatively impact demand for our products. Future pandemics and public crises could impact our business in a similar or worse manner. For additional information, see Note 1 to our consolidated financial statements.

 

Political, economic, social and regulatory risks

 

Political, economic and social conditions in the countries in which we have operations or projects could adversely impact our business, financial condition results of operations and the trading price of our securities.

 

Political, economic and social conditions in the countries in which we have operations or projects may negatively affect our financial performance. Our business, financial position and results of operations may be affected by the general conditions of the Peruvian, Brazilian and other national political conditions, economies, economic recessions, price instability, exchange rate volatility, inflation, interest rates, and domestic regulatory and taxation policies. There can be no assurance that the countries in which we operate will not face political, economic or social problems in the future or that these problems will not increase the volatility of the price of securities of issuers with operations in those countries, like us, or interfere with our ability to service our indebtedness.

 

In all these countries, we are exposed to various additional risks over which we have no control, such as social unrest, bribery, cyberattacks, extortion, corruption, robbery, sabotage, kidnapping, civil strife, terrorism, acts of war and guerilla activities. These issues may adversely affect the economic and other conditions under which we operate in ways that could have a materially negative effect on our business.

 

Recent and potential changes in commercial and mining laws may significantly impact our mining operations.

 

Changes to the Brazilian and Peruvian regulatory framework that could be enacted in the future may result in an increase in our expenses, particularly mining royalties. In addition, any changes in the interpretation of Brazilian or Peruvian mining laws and regulations, including changes to our concession agreement and changes in commercial rules and protections, may increase our compliance, operational or other costs. For additional information, see “Information on the Company—Regulatory matters—Brazilian regulatory framework—Mining rights and regulation of mining activities.”

 

16

 

 

Risk Factors

 

Our mineral rights may be terminated or not renewed by governmental authorities.

 

Our business is subject to extensive regulation in Brazil and Peru, including with respect to acquiring and renewing the required authorizations, permits, concessions and/or licenses from the relevant governmental regulatory bodies. We have obtained, or are in the process of obtaining, all material authorizations, permits, concessions and licenses required to conduct our mining and mining-related operations.

 

In Brazil, we may need to renew exploration authorizations related to our Brazilian mining operations 60 days prior to their expiration date if we determine that we continue to have an economic or business interest in the area. If we fail to demonstrate the existence of technical and economically viable mineral deposits in an area covered by an exploration authorization, we may be required to return it to the federal government. The federal government may then grant exploration authorizations to other parties that may conduct other mineral prospecting activities at said area. With respect to mining concessions, there is no renewal requirement once we have obtained such concession. However, we must continue to assess the mineral potential of each mining concession to determine if the costs of maintaining the related exploration authorizations and mining concessions are justified by the results of operations to date. If such costs are not justified and we abandon the mine or suspend the mining activities without the formal consent of the regulatory authority for a period more than six months, we may lose the respective mining concessions. Alternatively, we may elect to withdraw or assign some of our exploration authorizations or mining concessions.

 

In Peru, once mineral concessions are granted, they may not be revoked as long as the titleholder complies with two obligations, including payment of an annual fee and either achievement of the minimum annual production target or expenditure of the equivalent amount in exploration or investments before the statutory deadline. If the production, expenditure or investment targets are not met, a statutory penalty must be paid. Accordingly, mineral concessions will lapse automatically if any of these obligations are not met within the statutory terms given to do so. Mining concessions in Peru may be terminated if the concessionaire does not comply with its obligations.

 

These authorizations, permits, concessions and environmental licenses are subject to our compliance with conditions imposed and regulations promulgated by the relevant governmental authorities. While we anticipate that all required authorizations, permits, concessions and environmental licenses or their renewals will be granted as and when sought, there is no assurance that these items will be granted as a matter of course, and there is no assurance that new conditions will not be imposed in connection with such renewals. If we were to violate any of the foregoing laws and regulations or the conditions of our concessions, authorizations and environmental licenses, we may be subjected to substantial fines or criminal sanctions, revocations of operating permits or licenses and possible closings of certain of our facilities.

 

Our operations depend on our relations and agreements with local communities, and new projects require carrying out a prior consultation procedure.

 

There are several local communities that surround our operations in Brazil and Peru, most of which we have entered into agreements with that provide for the use of their land for our operations. We also interact with regional and local governments and depend on our close relations with local communities and such governments to carry out our operations. From time to time, we may experience disputes with local communities and if our relations with the local communities and such governments were to deteriorate, or the local communities do not comply with the existing agreements or renew them upon expiration, it could have a material adverse effect on our business, properties, operating results, financial position or prospects. In addition, a disruption in the relations between the local communities, governments and other parties may affect us indirectly. For example, see “Mining Operations—Atacocha—Production.”

 

We also may face certain risks in relation to artisanal mining near the areas in which we operate. The increase of artisanal mining activity or the failure of these artisanal miners to abide with our existent agreement may have an adverse effect on the development of our operations. For example, see “Mining Operations—Aripuanã—History.”

 

Furthermore, to develop new projects in the countries in which we operate on land owned by, or in the possession of, third parties, we need to reach an agreement with such third parties to use that land. Any delay or failure to reach such agreements or obtain governmental approvals for our new projects could result in a material adverse effect on our business, properties, operating results, financial position or prospects.

 

17

 

 

Risk Factors

 

Changes in tax laws may increase our tax burden and, as a result, could adversely affect our business, financial position and results of operations.

 

The Brazilian, Peruvian and Luxembourg governments from time to time implement changes to tax laws and regulations. Any such changes, as well as changes in the interpretation of such laws and regulations, may result in increases to our overall tax burden, which would negatively affect our profitability. Moreover, some tax laws may be subject to controversial interpretation by tax authorities, including, but not limited to, the regulation applicable to corporate restructurings. In the event an interpretation different than the one on which we based our transactions prevails, we may be adversely affected. We cannot assure shareholders that the Brazilian, Peruvian or Luxembourg governments will not implement additional changes to tax regulations in the future, which could adversely affect our business, financial position and results of operations.

 

Our business, financial position and results of operations may be adversely affected by inflation.

 

Certain of the countries in which we operate have in the past experienced high levels of inflation and may experience high levels of inflation in the future, which may impact domestic demand for our products. Inflationary pressures may curtail our ability to access international financial markets and may lead to further government intervention in the economy, including the introduction of government policies that may materially adversely affect the overall performance of the national economy of the countries in which we operate, which in turn may materially adversely affect us. We may not be able to adjust the prices we charge our customers to offset the effects of inflation on our cost structure. In addition, although the functional currency for our Peruvian operations is the U.S. dollar, high rates of inflation could increase our operating costs and adversely impact our operating margins if we are not able to pass the increased costs on to consumers.

 

We are subject to anti-corruption, anti-bribery and anti-money laundering laws and regulations in various jurisdictions. Any violations of any such laws or regulations could have a material adverse impact on our reputation and results of operations and financial position.

 

We are subject to anti-corruption, anti-bribery, anti-money laundering and other international laws and regulations and are required to comply with the applicable laws and regulations of Brazil, Peru, Luxembourg, Canada and the United States, among others. In addition, we are subject to economic sanctions regulations that restrict our dealings with certain sanctioned countries, individuals and entities. Our governance and compliance processes may not timely identify or prevent future breaches of legal, accounting or governance standards. We may be subject to instances of fraudulent behavior, corrupt practices and dishonesty by our affiliates, employees, directors, officers, partners, agents and service providers. Any violations by us of anti-bribery and anti-corruption laws, sanctions regulations or other standards could have a material adverse effect on our business, reputation, results of operations and financial position.

 

Political and social opposition to mining activities generally in the regions where we operate could adversely impact our business and reputation.

 

Disputes with communities where we operate may arise from time to time. In some instances, our operations and mineral reserves are located on or near lands owned or used by indigenous people or other groups of stakeholders. Some of our mining and other operations are in territories where title may be subject to disputes or uncertainties, or in areas claimed for agriculture or land reform purposes, which may lead to disagreements with organized social movements, local communities and the government. We may be required to consult and negotiate with these groups as part of the process to obtain licenses required to operate, to mitigate impact on our operations or to obtain access to their lands. Disagreements or disputes with local groups, including indigenous groups, organized social movements and local communities, could cause delays or interruptions to our operations, adversely affect our reputation or otherwise hamper our ability to develop our reserves and conduct our operations. Protesters have taken actions to disrupt our operations and projects, and they may continue to do so in the future, which may harm our operations and could adversely affect our business. In recent years, Peru has experienced protests against mining projects in several regions. On several occasions, local communities have opposed these operations and accused them of polluting the environment and hurting agricultural and other traditional economic activities. Social demands and conflicts could have a material adverse effect on our business and results of operations and the economy in general of the countries in which we operate.

 

18

 

 

Risk Factors

 

Uncertainty in governmental agency interpretation or court interpretation and the application of such laws and regulations could result in unintended non-compliance.

 

The courts in some of the jurisdictions in which we operate may offer less certainty as to the judicial outcome of legal proceedings or a more protracted judicial process than is the case in more established economies. Businesses can become involved in lengthy court cases over simple issues when rulings are not clearly defined, and the poor drafting of laws and excessive delays in the legal process for resolving issues or disputes compound such problems. In addition, there may be limited or no relevant case law providing guidance on how courts would interpret such laws and the application of such laws to our contracts, joint ventures, licenses, license applications or other legal arrangements. Accordingly, there can be no assurance that contracts, joint ventures, licenses, license applications or other legal arrangements will not be adversely affected by the actions of government authorities and the effectiveness of and enforcement of such arrangements in these jurisdictions. Moreover, the commitment of local businesses, government officials and agencies and the judicial system in these jurisdictions to abide by legal requirements and negotiated agreements may be more uncertain and may be susceptible to revision or cancellation, and legal redress may be uncertain or delayed. These uncertainties and delays could have a material adverse effect on our business and results of operations.

 

Risks relating to our corporate structure

 

VSA has substantial control over us, which could limit our shareholders’ ability to influence the outcome of important corporate decisions.

 

As of March 22, 2021, VSA owns 64.68% of our issued and outstanding common shares. As a result, VSA can influence or control matters requiring approval by our shareholders, including the election of directors, the allocation of profits, the appointment of external auditors and the approval of mergers, acquisitions or other extraordinary transactions. VSA may also have interests that differ from our other investors and may vote in a way with which our other shareholders disagree, and which may be adverse to the interests of our other investors.

 

In addition, we have entered into several shared services contracts and similar agreements with other entities in the Votorantim Group in order to achieve operational economies of scale. Since we rely on the Votorantim Group for negotiation, renewal and extension of these agreements, there can be no assurances that we will always have access to the services procured pursuant to these agreements at the same prices and conditions. See “Share ownership and trading—Related Party Transactions.”

 

Dividends or other distributions paid by us on our common shares will generally be subject to Luxembourg withholding tax.

 

Any dividends or other distributions paid by us on our common shares will be subject to a Luxembourg withholding tax at a rate of 15.0% unless an exemption or reduction in rate applies. The withholding tax must be withheld from the gross distribution and paid to the Luxembourg tax authorities. Under certain circumstances, distributions as share capital reductions or share premium reimbursements may not be subject to withholding tax, but there are no assurances that we will be able to make such distributions in the future. See “Additional Information—Taxation—Luxembourg tax considerations—Shareholders.”

 

The rights of our shareholders, and the responsibilities of VSA as our controlling shareholder, are governed by Luxembourg law and differ in some respects from the rights and responsibilities of shareholders under the laws of other jurisdictions, including the United States and Canada, and shareholders may have more difficulty protecting their interests than they would as shareholders of a U.S. or Canadian corporation.

 

Our corporate affairs are governed by our articles of association and by the laws governing limited liability companies organized under the laws of Luxembourg, as well as such other applicable local law, rules and regulations. The rights of our shareholders and the responsibilities of VSA as our controlling shareholder and of our directors and officers under Luxembourg law are different from those applicable to a corporation incorporated in the United States or Canada. There may be less publicly available information about us than is regularly published by or about U.S. or Canadian issuers. Also, Luxembourg regulations governing the securities of Luxembourg companies may not be as extensive as those in effect in the United States or Canada, and Luxembourg law and regulations in respect of corporate governance matters may not be as protective of non-controlling shareholders as corporation laws in the United States or Canada. Therefore, shareholders may have more difficulty protecting their interests in connection with actions taken by us, our directors and officers or our principal shareholders than they would as shareholders of a corporation incorporated in the United States or Canada.

 

19

 

 

Risk Factors

 

Our ability to make distributions on our common shares is subject to a number of factors and conditions.

 

The determination to pay dividends and the payment of dividends or other distributions (including reimbursements of share premium) will be subject to the approval of our board of directors and/or our shareholders, as applicable, and will depend on a number of factors, including, but not limited to, our cash balance, cash flow, earnings, capital investment plans, expected future cash flows from operations, our strategic plans and cash dividend distributions from our subsidiaries, as well as restrictions imposed by applicable law and contractual restrictions (although as of the date of this report there are no contractual restrictions on our ability to pay dividends or other distributions to our shareholders), and other factors our board of directors may deem relevant at the time. Luxembourg law also imposes certain requirements regarding distributions. For additional information, see “Share ownership and trading—Distributions.”

 

We are a holding company and have no material assets other than our ownership of shares in our subsidiaries. When we pay a dividend or other distribution on our common shares in the future, we generally cause our operating subsidiaries to make distributions to us in an amount sufficient to fund any such dividends or distributions. Although as of December 31, 2020, there are no material contractual restrictions on our subsidiaries’ ability to make distributions to us, their ability to do so is subject to their capacity to generate sufficient earnings and cash flow and may also be affected by statutory accounting and tax rules in Brazil and Peru.

 

It could be difficult for investors to enforce any judgment obtained outside Luxembourg against us or any of our associates.

 

We are organized under the laws of Luxembourg. Furthermore, certain of our directors and officers reside outside the United States and Canada and most of their assets are located outside the United States and Canada. Most of our assets are located outside the United States or Canada. As a result, it may not be possible for investors to effect service of process upon us or our directors and officers within the United States, Canada or other jurisdictions outside Luxembourg or to enforce against us or our directors and officers, judgments obtained in the United States, Canada or other jurisdictions outside Luxembourg. Because judgments of United States or Canadian courts for civil liabilities based upon the U.S. federal securities laws or Canadian securities laws may only be enforced in Luxembourg if certain requirements are met, investors may face greater difficulties in protecting their interest in actions against us or our directors and officers than would investors in a corporation incorporated in a state or other jurisdiction of the United States or Canada.

 

20

 

 

 

Selected Financial Data

 

Selected financial data

 

The following tables present our selected consolidated financial data for each of the periods and the dates indicated below.

 

The selected consolidated financial data should be read in conjunction with the consolidated financial statements included elsewhere in this report. Our consolidated financial statements have been prepared in accordance with IFRS.

 

    For the Year Ended December 31,  
    2020     2019     2018  
    (in millions of US$, unless otherwise indicated)  
Consolidated income statement information:                        
Continuing operations                        
Net revenues     1,950.9       2,332.7       2,491.7  
Cost of sales     (1,563.9 )     (1,947.8 )     (1,892.2 )
Gross profit     387.0       384.9       599.4  
Operating expenses:                        
Selling, general and administrative     (151.6 )     (216.5 )     (159.6 )
Mineral exploration and project evaluation     (57.2 )     (119.1 )     (129.6 )
Impairment loss     (557.5 )     (142.1 )     (3.3 )
Other income and expenses, net     (19.2 )     (18.2 )     27.6  
Total operating expenses     (785.5 )     (495.9 )     (264.9 )
Operating income (loss)     (398.5 )     (111.0 )     334.6  
Financial income     11.2       31.1       67.5  
Financial expenses     (159.8 )     (117.4 )     (119.1 )
Other financial items, net     (129.6 )     (18.5 )     (151.0 )
Net financial results     (278.2 )     (104.9 )     (202.7 )
Share in the results of associates                  
(Loss) Income before income tax     (676.7 )     (215.9 )     131.9  
Current income tax     (63.2 )     (46.4 )     (71.8 )
Deferred income tax     87.3       104.7       33.0  
Net (loss) income for the year from continuing operations     (652.6 )     (157.5 )     93.1  
Discontinued operations                  
Net (loss) income for the year     (652.6 )     (157.5 )     93.1  
Net (loss) income attributable to:                        
Nexa Resources’ shareholders     (559.2 )     (145.1 )     77.0  
Non-controlling interests     (93.3 )     (12.4 )     16.1  
Weighted average number of outstanding shares (in millions)     132.4       132.6       133.3  
Basic and diluted (loss) earnings per share (in US$)     (4.2 )     (1.1 )     0.58  

 

21

 

 

Selected Financial Data

 

    As of December 31,  
    2020     2019     2018  
    (in millions of US$)  
Consolidated Balance Sheet Information:                        
Assets                        
Cash and cash equivalents     1,086.2       698.6       1,032.9  
Financial investments     35.0       58.4       91.9  
Inventory     256.5       295.3       269.7  
Total current assets     1,727.2       1,375.3       1,698.0  
Property, plant and equipment     1,898.3       2,122.7       1,968.5  
Intangible assets     1,076.4       1,538.5       1,742.5  
Total non-current assets     3,337.0       4,091.0       4,019.4  
Total assets     5,064.2       5,466.3       5,717.4  
Liabilities                        
Loans and financing (current)     146.0       33.1       32.5  
Trade payables     370.1       414.1       387.2  
Total current liabilities     876.6       699.0       651.8  
Loans and financing (non-current)     1,878,3       1,475.4       1,392.4  
Total non-current liabilities     2,566.4       2,285.2       2,203.1  
Total liabilities     3,443.0       2,984.2       2,854.9  
Shareholders’ equity                        
Total equity attributable to owners of the parent     1,377.4       2,109.6       2,437.2  
Non-controlling interests     243.8       372.6       425.2  
Total shareholders’ equity     1,621.2       2,482.2       2,862.4  
Total liabilities and shareholders’ equity     5,064.2       5,466.3       5,717.4  

 

    For the Year Ended December 31,  
Consolidated Statement of Cash Flows Information   2020     2019     2018  
    (in millions of US$)  
Net cash provided by (used in):                        
Operating activities     291.7       122.8       347.6  
Investing activities     (369.2 )     (335.4 )     (158.1 )
Financing activities     451.6       (119.3 )     (177.4 )
Other highly liquid short-term investments (1)     29.5              
Effects of exchange rates on cash and cash equivalents     (16.1 )     (2.5 )     1.8  
Increase (decrease) in cash and cash equivalents     387.5       (334.3 )     13.9  
Cash and cash equivalents at the beginning of the year     698.6       1,032.9       1,019.0  
Cash and cash equivalents at the end of the year     1,086.2       698.6       1,032.9  

 

 

(1) See Note 15(a) to our Consolidated financial statements at December 31, 2020.

 

    As of and For the Year Ended December 31,  
    2020     2019     2018  
    (in millions of US$, except financial ratios)  
Other Financial Information                        
Depreciation and amortization     243.9       317.9       267.2  
Interest paid on loans and financing     (69.9 )     (71.8 )     (74.6 )
Adjusted working capital (1)     99.4       158.7       93.1  
Adjusted EBITDA (1)     402.9       349.0       604.8  
Adjusted EBITDA by segment (1):                        
Mining     140.5       172.6       430.4  
Smelting     269.2       180.0       174.8  
Other (2)     (6.8 )     (3.6 )     (0.4 )
Total     402.9       349.0       604.8  
Net debt (period end) (1)     923.7       787.8       302.8  
Net debt to Adjusted EBITDA ratio (1)     2.3       2.3       0.5  

 

 

(1) See discussion (Non-IFRS) below.

 

(2) The line item “Other” represents the residual component of Adjusted EBITDA either not pertaining to the mining or smelting segments, or, represents items that, because of their nature, are not being allocated to a specific segment.

 

22

 

 

Selected Financial Data

 

Non-IFRS measures and reconciliation

 

Our management uses non-IFRS measures such as Adjusted EBITDA, among other measures, for internal planning and performance measurement purposes. We believe these measures provide useful information about the financial performance of our operations that facilitates period-to-period comparisons on a consistent basis. Management uses Adjusted EBITDA internally to evaluate our underlying operating performance for the reporting periods presented and to assist with the planning and forecasting of future operating results. Management believes that Adjusted EBITDA is a useful measure of our performance because it reflects our cash generation potential from our operational activities excluding impairment of non-current assets and other miscellaneous adjustments, if any, for the period. These measures should not be considered individually or as a substitute for net income or operating income, as indicators of operating performance, or as alternatives to cash flow as measures of liquidity. Additionally, our calculation of Adjusted EBITDA and other non-IFRS measures may be different from the calculation used by other companies, including our competitors in the mining industry, so our measures may not be comparable to those of other companies.

 

In this report, we present Adjusted EBITDA, which we define as net (loss) income for the year, adjusted by (i) share in the results of associates, (ii) depreciation and amortization, (iii) net financial results, (iv) income tax, (v) (loss) gain on sale of investments, and (vi) impairment and impairment reversals. In addition, management may adjust the effect of certain types of transactions that in management’s judgment are not indicative of our normal operating activities or do not necessarily occur on a regular basis.

 

A reconciliation of Adjusted EBITDA to our net income for the years indicated is presented below.

 

    For the Year Ended December 31,  
    2020     2019     2018  
    (in millions of US$)  
Reconciliation of Adjusted EBITDA:                        
Net (loss) income for the year     (652.6 )     (157.5 )     93.1  
(+) Share in the results of associates                  
(+) Depreciation and amortization     243.9       317.9       267.2  
(−/+) Net financial results     278.2       104.8       202.7  
(−/+) Income tax     (24.1 )     (58.3 )     38.8  
(−/+) Impairment of non-current assets (1)     557.5       142.1       3.3  
(−/+) Gain on sale of investments and other miscellaneous adjustments (1)                 (0.2 )
Adjusted EBITDA     402.9       349.0       604.8  

 

(1) For the year ended December 31, 2019 and 2018, this line was described as “Exceptional items.”

 

We define Adjusted EBITDA by segment as net income (loss) for the year, adjusted by (i) share in the results of associates, (ii) depreciation and amortization, (iii) net financial results, (iv) income tax, (v) gain on sale of investments, and (vi) impairment and impairment reversals. See Note 2 to our consolidated financial statements.

 

23

 

 

Selected Financial Data

 

A breakdown of the Adjusted EBITDA by segment is presented below.

 

    For the Year Ended December 31,  
    2020     2019     2018  
    (in millions of US$)  
Breakdown of Adjusted EBITDA by segment:                        
Mining     140.5       172.6       430.4  
Smelting     269.2       180.0       174.8  
Other (1)     (6.8 )     (3.6 )     (0.4 )
Adjusted EBITDA     402.9       349.0       604.8  

 

 

(1) Represents the residual component of Adjusted EBITDA either not pertaining to the mining or smelting segments, or, represents items that, because of their nature, are not being allocated to a specific segment.

 

We also present herein our net debt, which we define as (i) loans and financing and lease liabilities less (ii) cash and cash equivalents, less (iii) financial investments, plus/less (iv) the fair value of derivative financial liabilities or assets, respectively. Our management believes that net debt is an important figure because it indicates our ability to repay outstanding debts that become due simultaneously using available cash and highly liquid assets.

 

A reconciliation of net debt to loans and financing as of December 31, 2020, 2019, and 2018 is presented below.

 

    As of December 31,  
    2020     2019     2018  
    (in millions of US$)  
Calculation of Net Debt:                        
Loans and financing     2,024.3       1,508.6       1,424.9  
Derivative financial instruments     (5.1 )     2.3       3.0  
Lease liabilities     25.7       34.4        
Cash and cash equivalents     (1,086.2 )     (698.6 )     (1,032.9 )
Financial investments     (35.0 )     (58.8 )     (92.2 )
Net Debt     923.7       787.8       302.7  

 

We define net debt to Adjusted EBITDA ratio as net debt divided by Adjusted EBITDA.

 

The calculation of our net debt to Adjusted EBITDA ratio for the periods indicated is presented below.

 

    As of and For the Year Ended December 31,  
    2020     2019     2018  
    (in millions of US$)  
Calculation of Net Debt to Adjusted EBITDA Ratio:                        
Net debt (period end)     923.7       787.8       302.7  
Adjusted EBITDA     402.9       349.0       604.8  
Net Debt to Adjusted EBITDA Ratio     2.3       2.3       0.5  

 

24

 

 

Selected Financial Data

 

We define Adjusted EBITDA margin as Adjusted EBITDA divided by net revenues. The calculation of our Adjusted EBITDA margin for the periods indicated is presented below.

 

    For the Year Ended December 31,  
    2020     2019     2018  
    (in millions of US$)  
Calculation of Adjusted EBITDA Margin:                        
Adjusted EBITDA     402.9       349.0       604.8  
Net revenue     1,950.9       2,332.7       2,491.7  
Adjusted EBITDA Margin     20.7 %     15.0 %     24.3 %

 

We calculate adjusted working capital as (i) trade accounts receivable, plus (ii) inventory, plus (iii) other assets, less (iv) trade payables, less (v) confirming payable, less (vi) salaries and payroll charges, less (vii) other liabilities. Our management believes that adjusted working capital is an important figure because it provides a relevant metric for the efficiency and liquidity of our operating activities.

 

The calculation of our adjusted working capital derived from our consolidated financial statements as of December 31, 2020, 2019, and 2018 is presented below.

 

    As of December 31,  
    2020     2019     2018  
    (in millions of US$)  
Calculation of Adjusted Working Capital:                        
Trade accounts receivable     229.0       177.2       173.2  
Inventory     256.5       295.3       269.7  
Other assets     184.3       241.9       243.3  
Trade payables     (370.1 )     (414.1 )     (387.2 )
Confirming payable     (145.3 )     (82.8 )     (70.4 )
Other liabilities     (55.0 )     (58.9 )     (135.5 )
Adjusted working capital     99.4       158.7       93.1  

 

 

(1) This amount relates to Other assets as presented in our consolidated financial statements.
(2) This amount relates to the Other liabilities as presented in our consolidated financial statements.

 

Cash cost, net of by-product credits and related measures

 

In this report, we also present measures of costs that are widely used by peer companies operating in the mining and smelting industries. These performance measures are not IFRS measures, and they do not have a standard meaning and therefore may not be comparable to similar data presented by other mining and smelting companies. They should not be considered as a substitute for costs of sales, costs of selling and administrative expenses, or as an indicator of costs. Similar measures are also calculated by Wood Mackenzie for many market participants, but Wood Mackenzie’s methodology differs from the methodology we use below.

 

Our management uses cash cost, net of by-product credits and related measures, among other measures, for internal planning and performance measurement purposes. We believe these measures provide useful information about the operational performance of our operations that facilitates period-to-period comparisons on a consistent basis.

 

In calculating cash cost, net of by-product credits, we account for transactions between our mining operations and our smelting operations using the same methodology we use to evaluate the performance of our mining and smelting segments. See Note 2 to our consolidated financial statements. We prepare an internal calculation based on transfer pricing adjustments made on an arm’s length principle basis. All information disclosed for cash cost, net of by-product credits is consistent with this methodology.

 

25

 

 

Selected Financial Data

 

Mining operations

 

Cash cost, net of by-product credits: For our mining operations, cash cost, net of by-product credits includes all direct costs associated with mining, concentrating, leaching, solvent extraction, on-site administration and general expenses, any off-site services essential to the operation, concentrate freight costs, marketing costs and property and severance taxes paid to state or federal agencies that are not profit-related. Treatment and refining charges on metal sales, which are typically recognized as a deduction component of sales revenues, are added to cash cost. Cash cost is calculated on a contained zinc sold basis, which indicates the percentage of zinc in metal sold, after the deduction of by-product credits attributable to mining operations, such as copper, silver, gold, and lead, which are deducted from total cash cost.

 

Sustaining cash cost, net of by-product credits: Sustaining cash cost, net of by-product credits is defined as the cash cost, net of by-product credits plus non-expansion capital expenditure, including sustaining health, safety and environment, modernization and other non-expansion-related capital expenditures.

 

All-in sustaining cost, net of by-product credits: All-in sustaining cost (“AISC”) is defined as sustaining cash cost, net of by-product credits plus corporate general and administrative expenses, royalties and workers’ participation.

 

Our cash cost and AISC net of by-products credits are measured with respect to zinc sold.

 

For mining operations, we present below cash cost, net of by-product credits, sustaining cash cost, net of by-product credits and all-in sustaining cost and a reconciliation to our consolidated financial statements.

 

26

 

 

 

Selected Financial Data

 

For the year ended December 31, 2020

 

    Vazante     Morro Agudo     Cerro Lindo     El Porvenir     Atacocha     Consolidation of Operations    

Corporate
and
Others(1)

    Mining  
                                                 
    Operations (in millions of US$, unless otherwise indicated)  
Sales Volume (Zinc Contained in Concentrate)                                                                
Tonnes     147,990       25,177       96,198       35,734       10,389       315,488       0       315,488  
Cost of goods sold     80.2       50.2       311.1       135.9       58.7       636.2       (10.8 )     625.4  
On-site G&A     5.0       4.2       0       0       0       9.2       0       9.2  
By-product credits     (9.5 )     (15.0 )     (246.5 )     (67.4 )     (42.6 )     (381.0 )     15.9       (365.1 )
Treatment and refining charges     122.1       15.6       56.0       25.4       7.0       226.2       0       226.2  
Selling expenses     0.7       1.9       3.0       0.4       0.3       6.3       0       6.3  
Depreciation and amortization     (15.8 )     (10.0 )     (94.6 )     (27.8 )     (10.5 )     (158.7 )     (1.3 )     (160.0 )
Royalties     (2.0 )     (1.6 )     0       (0.7 )     (0.3 )     (4.6 )     0       (4.6 )
Workers’ participation & bonus     (1.3 )     (0.8 )     (6.0 )     (0.7 )     (0.5 )     (9.3 )     0       (9.3 )
Others     (4.7 )     (1.2 )     (23.9 )     (17.2 )     (11.9 )     (58.9 )     0       (58.9 )
Cash cost net of by-product credits (sold)     174.7       43.5       (0.8 )     47.8       0.2       265.4       3.8       269.2  
Cash cost net of by-product credits (sold) (US$/tonne)     1,180.6       1,726.9       (8.7 )     1,338.0       17.8       841.1       0       853.2  
Non-expansion capital expenditure     24.6       7.4       27.7       12.9       15.3       87.9       (10.8 )     77.1  
Sustaining cash cost net of by-product credits     199.4       50.9       26.8       60.8       15.5       353.3       (7.0 )     346.2  
Sustaining cash cost net of by-product credits (sold) (per tonne)     1,347.1       2,020.2       279.0       1,700.3       1,487.9       1,119.8       0       1,097.5  
Workers’ participation & bonus     1.3       0.8       6.0       0.7       0.5       9.3       0       9.3  
Royalties     2.0       1.6       0       1.2       0.4       5.1       0       5.1  
Corporate G&A                                         52.4       52.4  
AISC net of by-product credits (sold)                                               413.1  
AISC net of by-product credits (sold) (per tonne)                                               1,309.5  

 

27

 

 

Selected Financial Data

 

For the year ended December 31, 2019

 

    Vazante     Morro Agudo     Cerro Lindo     El Porvenir     Atacocha     Consolidation of Operations    

Corporate
and
Others(1)

    Mining  
                                                 
    Operations (in millions of US$, unless otherwise indicated)  
Sales Volume (Zinc Contained in Concentrate)                                                                
Tonnes     139,041       24,354       125,153       54,725       16,360       359,633             359,633  
Cost of goods sold     90.9       62.6       369.3       171.6       112.3       806.7       (1.7 )     805.1  
On-site G&A     8.6       7.3       0.0       0.0       0.0       15.9       0.0       15.9  
By-product credits     (6.4 )     (19.2 )     (270.5 )     (84.6 )     (70.8 )     (451.5 )     (0.3 )     (451.7 )
Treatment and refining charges     93.7       12.9       60.5       31.7       9.4       208.2       0.0       208.2  
Selling expenses     0.3       1.7       3.0       0.7       0.5       6.1       0.0       6.1  
Depreciation and amortization     (22.6 )     (11.7 )     (107.7 )     (43.9 )     (30.4 )     (216.4 )     (1.4 )     (217.9 )
Royalties     (1.7 )     (1.5 )     0.0       0.0       0.0       (3.2 )     (3.1 )     (6.3 )
Workers’ participation & bonus     (1.8 )     (0.9 )     (8.5 )     (1.9 )     (0.5 )     (13.6 )           (13.6 )
Others     (2.6 )     (0.7 )     (1.5 )     1.5       (3.2 )     (6.5 )           (6.5 )
Cash cost net of by-product credits (sold)     158.3       50.6       44.6       75.1       17.2       345.8       (6.5 )     339.3  
Cash cost net of by-product credits (sold) (US$/tonne)     1,138.5       2,076.7       356.0       1,372.9       1,052.0       961.5       0.0       943.5  
Non-expansion capital expenditure     42.7       12.8       50.5       32.9       11.8       150.8       3.7       154.5  
Sustaining cash cost net of by-product credits     201.0       63.4       95.1       108.1       29.0       496.5       (2.8 )     493.8  
Sustaining cash cost net of by-product credits (sold) (per tonne)     1,445.7       2,604.1       759.5       1,975.0       1,770.3       1,380.7       0.0       1,373.0  
Workers’ participation & bonus     1.8       0.9       8.5       1.9       0.5       13.6             13.6  
Royalties     1.7       1.5       0.0       1.7       1.0       5.9             5.9  
Corporate G&A                                         90.5       90.5  
AISC net of by-product credits (sold)                                               603.8  
AISC net of by-product credits (sold) (per tonne)                                               1,678.8  

 

28

 

 

Selected Financial Data

 

For the year ended December 31, 2018

 

    Vazante     Morro Agudo     Cerro Lindo     El Porvenir     Atacocha     Consolidation of Operations    

Corporate
and
Others(1)

    Mining  
                                                 
    Operations (in millions of US$, unless otherwise indicated)  
Sales Volume (Zinc Contained in Concentrate)                                                                
Tonnes     140,776       26,408       129,656       59,510       17,066       373,416             373,416  
Cost of goods sold     77.3       45.1       336.9       158.8       92.9       711.1       (0.0 )     711.1  
On-site G&A     5.9       5.7                   0.4       12.0             12.0  
By-product credits     (7.4 )     (17.7 )     (290.0 )     (73.3 )     (57.2 )     (445.7 )     0.7       (444.9 )
Treatment and refining charges     62.1       9.9       47.0       25.4       7.2       151.6             151.6  
Selling expenses           0.9       0.8       0.9       0.3       3.0             3.0  
Depreciation and amortization     (17.6 )     (5.6 )     (87.5 )     (36.5 )     (24.3 )     (171.5 )     (0.9 )     (172.4 )
Royalties     (1.7 )     (1.5 )                       (3.2 )     (3.3 )     (6.5 )
Workers’ participation & Bonus     (1.2 )     (0.7 )     (8.4 )     (4.0 )     (0.4 )     (14.7 )     0.0       (14.7 )
Others                 (5.4 )     (0.3 )           (5.7 )           (5.7 )
Cash cost net of by-product credits (sold)     117.5       36.0       (6.5 )     71.0       19.0       237.0       (3.5 )     233.5  
Cash cost net of by-product credits (sold) (US$/tonne)     834.5       1,363.8       (50.4 )     1,192.9       1,115.5       634.7             625.3  
Non-expansion capital expenditure     42.4       12.3       25.3       25.6       16.9       122.4       1.3       123.7  
Sustaining cash cost, after by-product credits     159.8       48.3       18.7       96.6       35.9       359.4       (2.2 )     357.2  
Sustaining cash cost net of by-product credits (sold) (per tonne)     1,135.5       1,829.5       144.3       1,623.2       2,105.5       962.5             956.7  
Workers’ participation & bonus     1.2       0.7       8.4       4.0       0.4       14.7       (0.1 )     14.5  
Royalties     1.7       1.5             1.9       0.9       6.0       0.0       6.1  
Corporate G&A                                         31.4       31.4  
AISC net of by-product credits (sold)(2)                                               409.3  
AISC net of by-product credits (sold)  (per tonne)                                               1,096.0  

 

 

(1) “Others” includes Enercan, inactive operations and non-operational provisions and reversals.

(2) Starting in 2018, certain expenses that were previously presented as General and administrative expenses and other income and expenses, net in our income statement were reclassified as mineral exploration and project evaluation expenses. As a result of this change, we have adjusted our calculations of AISC.

 

29

 

 

Selected Financial Data

 

Smelting operations

 

Cash cost, net of by-product credits: For our smelting operations, cash cost, net of by-product credits includes all the costs of smelting, including costs associated with labor, net energy, maintenance, materials, consumables and other on-site costs, as well as raw material costs. Cash cost is calculated on a contained zinc sold basis after the deduction of by-product credits attributable to smelting operations.

 

Sustaining cash cost, net of by-product credits: Sustaining cash cost, net of by-product credits is defined as the cash cost, after by-product credits plus non-expansion capital expenditure, including sustaining health, safety and environment, modernization and other non-expansion-related capital expenditures.

 

All-in sustaining cost, net of by-product credits: All-in sustaining cost is defined as sustaining cash cost, net of by-product credits plus general and administrative expenses and workers’ participation.

 

Our cash cost and AISC net of by-products credits are measured with respect to zinc sold.

 

For our smelting operations, we present below cash cost, net of by-product credits, sustaining cash cost, net of by-product credits and all-in sustaining cost and a reconciliation to our consolidated financial statements.

 

30

 

 

Selected Financial Data

 

For the year ended December 31, 2020

 

   

Três
Marias

   

Juiz de
Fora

   

Cajamarquilla

   

Consolidation
of Operations

   

Corporate
and
Others(1)

   

Smelting

 
    Operations (in millions of US$, unless otherwise indicated)  
Sales Volume (Zinc Contained in Products)                                                
Tonnes     196,327       77,965       302,495       576,788       0       576,788  
Cost of goods sold     363.9       187.3       739.8       1,291.0       (3.2 )     1,287.9  
Cost of services rendered     (10.1 )     (2.8 )     (34.9 )     (47.8 )     0       (47.8 )
On-site G&A     4.8       4.0       18.5       27.4       0       27.4  
Depreciation and amortization     (14.5 )     (11.7 )     (56.4 )     (82.7 )     0       (82.7 )
By-product credits     (14.6 )     (18.0 )     (83.9 )     (116.5 )     2.4       (114.1 )
Workers’ participation & Bonus     (1.2 )     (1.0 )     (7.6 )     (9.7 )     0       (9.7 )
Others     (12.1 )     (8.5 )     (8.0 )     (28.6 )     0       (28.6 )
Cash cost, net of by-product credits (sold)     316.2       149.3       567.6       1,033.1       (0.8 )     1,032.3  
Cash cost, net of by-product credits (sold) (per tonne)     1,610.4       1,915.4       1,876.4       1,791.1       0       1,789.8  
Non-expansion capital expenditure     18.1       9.8       15.6       43.5       (5.8 )     37.7  
Sustaining cash cost, net of by-product credits     334.3       159.1       583.2       1,076.6       (6.6 )     1,070.0  
Sustaining cash cost net of by-product credits (sold) (per tonne)     1,702.6       2,041.0       1,927.9       1,866.5       0       1,855.1  
Workers’ participation     1.2       1.0       7.6       9.7       0       9.7  
Corporate G&A     0       0       0       0       32.8       32.8  
AISC net of by-product credits (sold)     0       0       0       0       0       1,112.5  
AISC net of by-product credits (sold) (per tonne)     0       0       0       0       0       1,928.7  

 

31

 

 

Selected Financial Data

 

For the year ended December 31, 2019

 

   

Três
Marias

   

Juiz de
Fora

   

Cajamarquilla

   

Consolidation
of Operations

   

Corporate
and
Others(1)

   

Smelting

 
    Operations (in millions of US$, unless otherwise indicated)  
Sales Volume (Zinc Contained in Products)                                                
Tonnes     186,482       85,411       340,293       612,185             612,185  
Cost of goods sold     456.5       242.3       956.3       1,655.1             1,655.1  
Cost of services rendered     (11.0 )     (4.0 )     (40.4 )     (55.4 )           (55.4 )
On-site G&A     5.3       5.0       16.0       26.3       0.2       26.5  
Depreciation and amortization     (19.1 )     (15.1 )     (63.8 )     (98.0 )           (98.0 )
By-product credits     (12.6 )     (19.1 )     (108.9 )     (140.6 )           (140.6 )
Workers’ participation & Bonus     (1.7 )     (1.2 )     (3.8 )     (6.6 )     (0.0 )     (6.6 )
Others     (8.0 )     (4.5 )     0.0       (12.5 )     0.0       (12.5 )
Cash cost, net of by-product credits (sold)     409.4       203.5       755.4       1.368,3       0.2       1,368.5  
Cash cost, net of by-product credits (sold) (per tonne)     2,195.6       2,382.1       2,219.9       2,235.1             2,235.4  
Non-expansion capital expenditure     26.9       18.7       18.2       63.8       3.8       67.6  
Sustaining cash cost, net of by-product credits     436.3       222.1       773.6       1.432,1       4.0       1,436.1  
Sustaining cash cost net of by-product credits (sold) (per tonne)     2,339.8       2,600.9       2.273,4       2,339.3             2,345.9  
Workers’ participation     1.7       1.2       3.8       6.6       0.0       6.6  
Corporate G&A     0,0       0.0       0.0       0.0       58.5       58.5  
AISC net of by-product credits (sold)     0.0       0.0       0.0       0.0             1,501.2  
AISC net of by-product credits (sold) (per tonne)                                   2,452.2  

 

32

 

 

Selected Financial Data

 

For the year ended December 31, 2018

 

   

Três
Marias

   

Juiz de
Fora

   

Cajamarquilla

   

Consolidation
of Operations

   

Corporate
and
Others(1)

   

Smelting

 
    Operations (in millions of US$, unless otherwise indicated)  
Sales Volume (Zinc Contained in Products)                                                
Tonnes     197,372       78,106       332,036       607,514             607,514  
Cost of goods sold     587.7       240.6       1,067.3       1,895.6       (16.9 )     1,878.8  
Cost of services rendered     (11.5 )     (3.5 )     (35.9 )     (50.8 )           (50.8 )
On-site G&A     4.3       6.6       15.4       26.3       2.2       28.4  
Depreciation and amortization     (15.6 )     (13.1 )     (64.8 )     (93.6 )     (1.2 )     (94.8 )
By-product credits     (14.4 )     (23.0 )     (75.6 )     (113.1 )     3.8       (109.3 )
Workers’ participation & Bonus     (0.9 )     (1.0 )     (1.5 )     (3.4 )     (0.0 )     (3.4 )
Others                                    
Cash cost net of by-product credits (sold)     549.6       206.5       905.0       1,661.0       (12.1 )     1,648.9  
Cash cost net of by-product credits (sold) (per tonne)     2,784.6       2,643.4       2,725.5       2,734.1             2,714.2  
Non-expansion capital expenditure     38.7       20.6       19.3       78.6       6.8       85.5  
Sustaining cash cost net of by-product credits     588.3       227.1       924.3       1,739.7       (5.3 )     1,734.4  
Sustaining cash cost net of by-product credits (sold) (per tonne)     2,980.7       2,907.5       2,783.6       2,863.6             2,854.8  
Workers’ participation     0.9       1.0       1.5       3.4       0.2       3.6  
Corporate G&A                             52.8       52.8  
AISC net of by-product credits (sold)(2)                                   1,790.7  
AISC net of by-product credits (sold) (per tonne)                                   2,947.6  

 

 

(1) “Others” includes Enercan, inactive operations and non-operational provisions and reversals.

(2) Starting in 2018, certain expenses that were previously presented as General and administrative expenses and Other income and expenses, net in our income statement were reclassified as mineral exploration and project evaluation expenses. As a result of this change, we have adjusted our calculations of AISC.

 

33

 

 

 

Business Overview

 

I. Information on the Company

 

Business overview

 

Overview

 

We are a leading large-scale, low cost integrated zinc producer with over 60 years of experience developing and operating mining and smelting assets in Latin America.

 

We operate and own five long life polymetallic mines, three located in the Central Andes of Peru and two located in the state of Minas Gerais in Brazil. Our operations are large-scale, modern, mechanized underground and open pit mines. Our mines are proximately located to one another, which creates efficiencies. Two of our mines, Cerro Lindo in Peru and Vazante in Brazil, are among the top 30 largest zinc-producing mines in the world and, combined with our other mining operations, placed us among the top five producers of mined zinc globally in 2020, according to Wood Mackenzie. In addition to zinc, which accounted for 65.0% of our mined metal production in 2020 measured on a zinc equivalent basis, we produce substantial amounts of copper, lead, silver and gold as by-products, which reduce our overall costs to produce mined zinc. We are also building our sixth underground mine in Brazil, the Aripuanã project. Aripuanã is an underground polymetallic project containing zinc, lead and copper, located in the state of Mato Grosso, with estimated annual average production of 70kt of zinc, 24kt of lead, 4kt of copper, 1.8Moz of silver and 14.5koz of gold, which represents approximately 119kt of zinc equivalent production. Aripuanã production is scheduled to start at the beginning of 2022.

 

We also own a zinc smelter in Peru (Cajamarquilla) and two zinc smelters in Brazil (Três Marias and Juiz de Fora), which produce metallic zinc, zinc oxide and several by-products. We were the fifth largest producer of refined zinc globally in 2020, according to Wood Mackenzie. Our smelters are the only units in Latin America (excluding Mexico), resulting in benefits from higher premiums. Cajamarquilla is the only operating zinc smelter in Peru and was the seventh largest globally in 2020 by production volume, according to Wood Mackenzie. Peru is the third largest producer of mined zinc in the world, assuring long-term supply of zinc concentrates to Cajamarquilla. Given our proximity to concentrate producers (our own mines and third-party producers), we also benefit from freight parity.

 

Government authorities in the countries in which we operate, and in particular in Peru, implemented policies in response to the COVID-19 pandemic that negatively affected our financial position, results of operations and cash flows, particularly during the second quarter of 2020. On March 15, 2020, the Peruvian government declared a state of emergency in response to COVID-19, imposing operating restrictions on non-essential industries, which included the mining sector. The quarantine period was continuously extended until May 10, 2020.

 

In light of the government restrictions, Nexa suspended production at the Cerro Lindo, El Porvenir and Atacocha mines, and the Cajamarquilla smelter operated at reduced rates. During this period, mining activities were limited to critical operations with a minimum workforce to ensure appropriate maintenance, safety and security protocols. On May 6, 2020, the Peruvian government announced the conditions for the resumption of operations for different sectors, including mining operations above 5ktpd.

 

The Cerro Lindo and El Porvenir mines restarted operations on May 11, 2020 following the end of the state of emergency and gradually ramped up production in the second and third quarters of 2020. The Cajamarquilla smelter also gradually improved its operating rate from mid-May to July 2020.

 

The development of our Aripuanã project was also impacted by COVID-19, as we limited the mobilization of people to the site at the end of 1Q20 until mid-2Q20. As a result, the project’s timeline was also affected.

 

Following the supreme decree published by the Peruvian government that allowed medium-sized mines to restart operations, on June 8, 2020 we announced the resumption of the San Gerardo open pit mine at Atacocha. The Atacocha site includes two mines: the Atacocha underground mine and the San Gerardo open pit mine. As a result of COVID-19 and its impact on the macroeconomic environment, and given our efforts to reduce costs and improve operational efficiency, in June 2020 we also decided that the operations of the higher-cost Atacocha underground mine would remain suspended and placed it under care and maintenance, which it remains to date.

 

34

 

 

Business Overview

 

In Brazil, our mining and smelting operations operated at normal levels throughout the year, except for the Juiz de Fora smelter which operated at 60% of its normal production capacity in May and June, in anticipation of a lower market demand, but has since returned to normal operating levels.

 

As a response to COVID-19, we also took proactive measures to manage our liquidity position by assuming additional debt during the first half of 2020. We added approximately US$300 million to our cash balance through export credit notes in March and in April and a seven-year bond of US$500 million issue in June, using the proceeds to prepay certain existing financial indebtedness.

 

In 2020, our mining operations produced 313.1 thousand tonnes of zinc contained in concentrates, 28.2 thousand tonnes of copper contained in concentrates, 38.0 thousand tonnes of lead contained in concentrates, 6,826.0 thousand ounces of silver and 16.2 thousand ounces of gold, for a total of 498.3 thousand tonnes of metal on a zinc equivalent basis.

 

Our smelters produced 587.6 thousand tonnes of zinc metal available for sale in different formats and sizes during 2020, along with by-products, including sulfuric acid, silver concentrate, copper cement and copper sulfate. Our smelters process mostly zinc concentrate, 52.0% of which was sourced from our mines during 2020, and 48.0% purchased from third parties or obtained as secondary raw material. Approximately 99.0% of the total volume of the contained zinc in concentrates produced by our mines was processed by our own smelters in 2020, with the remainder and all our copper and lead concentrates sold to third parties. We market our products in Latin America and globally, through our commercial offices in Luxembourg, the United States, Brazil and Peru. We also own energy assets (hydroelectric power plants) in both Brazil and Peru, which provide access to a reliable and competitive power supply.

 

In response to the global COVID-19 pandemic, we also created a Crisis Committee, which includes all executive officers, certain key general managers and personnel to carry out preventive safety and health procedures in our operations and offices. We have implemented several measures to help protect our employees, contractors and local communities and we are working on three main fronts: (1) health, safety and people, (2) business continuity and (3) stakeholders. We also implemented business continuity measures to mitigate and reduce any impacts of the global outbreak on our operations, supply chain and financial situation. Our COVID-19 associated costs during 2020 amounted to US$15 million. The Crisis Committee remains in place and meets weekly. For more information, see “Operating and Financial Review and Prospects—Overview—Executive Summary—COVID-19” below.

 

History

 

We commenced operating in 1956 under the name “Companhia Mineira de Metais”, in the state of Minas Gerais, Brazil. After a series of restructurings in the subsequent fifty-eight years, in 2014, a new corporate governance model was implemented by our controlling shareholder VSA in the corporate group. VSA took on the roles of providing guidance and portfolio management, while its subsidiaries (including us) gained autonomy. The main consequence of this new corporate model was that the new governance structure demanded a higher level of empowerment and accountability of senior management, and the establishment of a board of directors at each company. In addition, in connection with the implementation of the new corporate governance model, VSA’s equity participations in Nexa CJM (formerly Votorantim Metais – Cajamarquilla S.A.) and Nexa Brazil (formerly Votorantim Metais Zinco S.A.) were transferred to Nexa Resources on June 18, 2014 and July 1, 2014, respectively.

 

In 2016, VSA reorganized the zinc, copper, aluminum and nickel businesses previously managed under the name Votorantim Metais S.A. The aluminum and nickel businesses of Votorantim Metais S.A. were consolidated under Companhia Brasileira de Alumínio, or CBA. The zinc and copper production units in Brazil and Peru were transferred to Nexa Resources. Following this reorganization, Nexa Resources became the holding entity solely responsible for the zinc and copper business and CBA became responsible for the aluminum and nickel businesses.

 

In October 2017, we completed our initial public offering and listed our common shares on the New York Stock Exchange (“NYSE”) and Toronto Stock Exchange (“TSX”) under the ticker symbol NEXA. In connection with becoming a public company, VM Holding S.A. changed its corporate name to Nexa Resources S.A. and our subsidiaries Votorantim Metais—Cajamarquilla S.A., Votorantim Metais Zinco S.A. and Compañía Minera Milpo S.A.A. changed their corporate names to Nexa CJM, Nexa Brazil and Nexa Peru, respectively.

 

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Business Overview

 

In 2018, our board of directors approved the construction of the Aripuanã greenfield project, an underground polymetallic project containing zinc, lead and copper, located in the state of Mato Grosso, Brazil. The project is part of our strategy of further integrating our mining and smelting operations and we believe that we can achieve synergies with our other operations in Brazil including our smelters.

 

In 2019, we launched the construction phase of the Aripuanã project, and have made progress with respect to developing the mine plan, underground development, building the project infrastructure, procurement and training, among others. In addition, we acquired full ownership of the Aripuanã project through the acquisition of Karmin Exploration Inc. (“Karmin”), which indirectly held a 30.0% interest in the Aripuanã project through its ownership of Dardanelos. As a result of this acquisition, and following the transfer of the Dardanelos 30% interest in the Aripuanã project from Nexa Peru to Nexa Brazil, Nexa Brazil became the owner of 100% of the Aripuanã project in June 2020.

 

On October 6, 2020, we published an update on the Aripuanã project taking into account revisions based on the impact of COVID-19 and other factors. Throughout 2020, we invested US$187 million to develop the Aripuanã project. Mechanical completion is expected in the fourth quarter of 2021 and production is scheduled to start in early 2022. For additional information, please see “Information on the Company—Mining operations—Greenfield projects—Aripuanã” and Note 32(g) to our consolidated financial statements.

 

On March 17, 2021, we acquired 29,895,754 common shares of Tinka Resources Limited (“Tinka”) (TSXV & BVL: TK) (OTCPK: TKRFF) from an arm’s length shareholder in a private transaction at a market price of C$0.26 per share. As a result, we own 8.8% of the outstanding common shares of Tinka, which is an exploration and development company with its flagship property being the 100% owned Ayawilca zinc-silver project comprising 170 sq km in central Peru.

 

Corporate structure and principal subsidiaries

 

Nexa CJM

 

Currently, Nexa Resources is the beneficial owner of 99.92% of the outstanding shares of Nexa CJM, and the remaining outstanding shares are owned by Nexa Recursos Minerais S.A. with 0.09% and by other minority shareholders holding 0.001% in aggregate.

 

Nexa Peru

 

Currently, Nexa Peru’s share capital consists of 1,309,748,288 common shares. In addition to common shares, Nexa Peru has issued investment shares that represent a participation in its net worth (patrimonio). Although the investment shares do not represent a participation in the capital of the Company nor grant any voting rights, they grant their holders the right, among others, to participate in any dividend distributions and liquidation proceeds, pro rata to the percentage they represent in the total net worth of Nexa Peru; as well as to participate in any capital increases (in order to maintain the participation they represent in the total net worth) and the right to have their shares redeemed in certain circumstances. As of December 31, 2020, approximately 67.0 % of the investment shares are free float and 33.0 % are treasury shares.

 

Both the common shares and the investment shares of Nexa Peru are registered with the Peruvian Public Registry of Securities (Registro Público del Mercado de Valores) and listed on the Lima Stock Exchange. As a result, Nexa Peru is required to comply with certain disclosure obligations such as filing quarterly and annual financial statements, reporting on material events (hechos de importancia) and disclosing information regarding the economic group to which it belongs.

 

The following table sets forth information concerning the ownership of the capital stock of Nexa Peru, excluding the investment shares.

 

Shareholder   Number     Share Capital (%)  
Nexa CJM     1,048,621,896       80.06 %
Nexa Resources     2,277,601       0.17 %
Public float     206,854,856       15.79 %
Treasury shares     51,993,935       3.97 %
Total     1,309,748,288       100.0 %

 

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Business Overview

 

Nexa Brazil

 

On June 26, 2020, Nexa Brazil, which is 100% owned by Nexa Resources, acquired Nexa Peru’s interest in Mineração Dardanelos Ltda. As a result, Nexa Brazil holds directly and indirectly 100% of the Aripuanã project.

 

Producing mines and smelters

 

Our mines are:

 

· Cerro Lindo. Our Cerro Lindo mine is an underground mine located in Peru wholly-owned by Nexa Peru. Operations began in 2007 and, in 2020, the Cerro Lindo mine produced approximately 95.4 thousand tonnes of zinc contained in concentrates, 27.8 thousand tonnes of copper contained in concentrates, 11.6 thousand tonnes of lead contained in concentrates, 2,939.0 thousand ounces of silver contained in concentrates and 4.0 thousand ounces of gold contained in concentrates. The ore is treated at a concentrate plant that has a processing capacity to 21.0 thousand tonnes of ore per day.

 

· Vazante. Our Vazante mine is an underground and open pit mine located in Brazil wholly-owned by Nexa Brazil. Operations began in 1969 and, in 2020, the Vazante mine produced approximately 148.0 thousand tonnes of zinc contained in concentrates, 1.3 thousand tonnes of lead contained in concentrates and 383.5 thousand ounces of silver contained in concentrates. The ore is treated at a concentrate plant that has a processing capacity of 4.1 thousand tonnes of ore per day.

 

· El Porvenir. Our El Porvenir mine is an underground mine located in Peru wholly-owned by Nexa Resources El Porvenir S.A.C. Operations began in 1949 and, in 2020, the El Porvenir mine produced approximately 34.9 thousand tonnes of zinc contained in concentrates, 0.3 thousand tonnes of copper contained in concentrates, 10.9 thousand tonnes of lead contained in concentrates, 2,315.2 thousand ounces of silver contained in concentrates and 5.9 thousand ounces of gold contained in concentrates. The ore is treated at a concentrate plant that has a processing capacity of 6.5 thousand tonnes of ore per day.

 

· Atacocha. Our Atacocha mine is an underground and open pit mine located in Peru wholly-owned by Nexa Resources Atacocha S.A.A. (formerly Compañía Minera Atacocha). Operations began in 1938 and, in 2020, the Atacocha mine produced approximately 9.6 thousand tonnes of zinc contained in concentrates, 10.2 thousand tonnes of lead contained in concentrates, 1,184.7 thousand ounces of silver contained in concentrates and 6.3 thousand ounces of gold contained in concentrates. The ore is treated at a concentrate plant that has a processing capacity of 4.5 thousand tonnes of ore per day. In response to COVID-19, the uncertain macroeconomic scenario and our efforts to reduce costs and improve operational efficiency, we decided to not resume the higher-cost Atacocha underground mine after the mandatory temporary suspension of our operations in Peru and placed it under care and maintenance, which it remains to date. See Note 1 to our consolidated financial statements for further information.

 

· Morro Agudo. Our Morro Agudo mine is an underground and open pit mine located in Brazil wholly-owned by Nexa Brazil. Operations began in 1988 and, in 2020, the Morro Agudo mine produced approximately 25.2 thousand tonnes of zinc contained in concentrates, 4.0 thousand tonnes of lead contained in concentrates and 3.5 thousand ounces of silver contained in concentrates. The ore mill feed material is treated at a concentrate plant that has a processing capacity of 3.4 thousand tonnes per day.

 

Our smelters are:

 

· Cajamarquilla. Our Cajamarquilla smelter, which is wholly-owned by Nexa CJM, is located in Peru and began operating in 1981. It is currently the largest zinc smelter in Latin America and was the seventh largest zinc smelter in the world in 2020, according to Wood Mackenzie. Cajamarquilla uses Roast-Leach-Electrowinning technology. With a nominal production capacity of 344.4 thousand tonnes of contained zinc per year, Cajamarquilla produced 305.4 thousand tonnes of zinc metal available for sales in 2020 and 340.4 thousand tonnes in 2019. In 2020, 37.2% of the zinc contained in raw material used by Cajamarquilla was sourced from our mines in Peru and 62.8% was purchased from third parties.

 

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Business Overview

 

· Três Marias. Our Três Marias smelter, which is wholly-owned by Nexa Brazil, is located in Brazil and began operating in 1969. Três Marias processes zinc silicate concentrate from our Vazante mine and zinc sulfide concentrate from our Morro Agudo mine and uses Roast-Leach-Electrowinning technology. With a nominal production capacity of 192.2 thousand tonnes per year, Três Marias produced 202.8 thousand tonnes of zinc metal and oxide available for sale in 2020 and 197.5 thousand tonnes in 2019. In 2020, 86.4% of the zinc contained in raw materials used by Três Marias was sourced from our mining operations in Brazil and Peru and 13.6% was purchased from third parties or obtained from secondary feed materials.

 

· Juiz de Fora. Our Juiz de Fora smelter, which is wholly-owned by Nexa Brazil, is located in Brazil and began operating in 1980. This smelter uses Roast-Leach-Electrowinning and Waelz Furnace technologies. With a nominal production capacity of 96.9 thousand tonnes per year, Juiz de Fora produced 79.4 thousand tonnes of zinc metal available for sale in 2020 and 86.2 thousand tonnes in 2019. In 2020, 26.3% of the zinc raw material consumption by Juiz de Fora was zinc concentrate sourced from our mining operations, 56.1% was purchased from third parties and 17.6% was obtained from secondary feed materials from electric arc furnace (“EAF”) and brass oxide.

 

In addition to our operating mines and smelters, we have interests in five greenfield mining projects in Peru (Shalipayco, Magistral, Hilarión, Pukaqaqa and Florida Canyon Zinc) and two in Brazil (Aripuanã, which is currently being developed and is considered a development stage property under a new subpart 1300 of Regulation S-K (“S-K 1300”), and Caçapava do Sul). For more information about these projects, please see “Information on the Company—Mining operations—Growth projects.”

 

38

 

 

Mining Operations

 

Mining operations

 

Map 1. Mines, Projects and Prospects in Peru 

 

 

Source: Nexa Resources.

 

39

 

 

Mining Operations

 

Map 2. Mines, Projects and Prospects in Brazil 

 

 

Source: Nexa Resources.

 

The following table summarizes our concentrate production, metal contained in concentrate production in each metal and zinc equivalent production in each of our operating mines.

 

To calculate the zinc equivalent production for the years ended December 31, 2020, 2019 and 2018, we convert the relevant metal contained in concentrate production used in the zinc equivalent grade based on the average benchmark prices for 2020, namely, US$2,267.0 per tonne (US$1.03 per pound) for zinc, US$6,180.6 per tonne (US$2.80 per pound) for copper, US$1,825.6 per tonne (US$0.83 per pound) for lead, US$20.5 per ounce for silver and US$1,769.6 per ounce for gold.

 

40

 

 

Mining Operations

 

    For the Year Ended December 31,  
    2020     2019     2018  
Treated Ore (in tonnes)     10,853,740       13,001,535       13,051,365  
Mining Production—Metal Contained in Concentrate                        
Zinc (in tonnes)     313,074       361,061       372,793  
Copper (in tonnes)     28,154       38,184       39,029  
Lead (in tonnes)     38,009       51,349       52,267  
Silver (in oz)(1)     6,825,882       8,900,995       7,992,167  
Gold (in oz)     16,179       24,955       29,224  
Mining Production—Zinc Equivalent Production                        
Cerro Lindo (in tonnes of zinc equivalent)     210,380       271,841       278,673  
El Porvenir (in tonnes of zinc equivalent)     70,106       109,241       103,324  
Atacocha (in tonnes of zinc equivalent)     33,459       54,358       57,482  
Vazante (in tonnes of zinc equivalent)     152,539       142,878       145,237  
Morro Agudo (in tonnes of zinc equivalent)     31,829       31,052       34,209  
Total     498,313       609,371       618,926  

 

 

(1) Silver volumes include silver in lead concentrate produced in Vazante.

 

The following table summarizes the average ore grade for the periods indicated.

 

    For the Year Ended December 31,  
    2020     2019     2018  
Average Ore Grade                        
Zinc (%)     3.28       3.16       3.27  
Copper (%)     0.33       0.37       0.38  
Lead (%)     0.49       0.52       0.53  
Silver (in ounces per tonne)     0.90       0.94       0.91  
Gold (in ounces per tonne)     0.005       0.006       0.005  

 

Each mine consists of one mine, one treatment plant and related infrastructure. We summarize below information as of December 31, 2020 for each of our five mines. For further information about our greenfield projects, including the Aripuanã project, which is in construction, see “Greenfield projects—Aripuanã.” For an overview of our reserves and resources, see “Mineral Reserves and Resources—Disclosure of mineral reserves and resources”, “Mineral Reserves and Resources—Mineral Reserves” and “Mineral Reserves and Resources—Mineral Resources.”

 

Cerro Lindo

 

Location and means of access

 

The Cerro Lindo mine is an underground, polymetallic mine located in the Chavín District, Chincha Province, Peru, approximately 268 km southeast of Lima and 60 km from the coast. Access from Lima is available via the paved Pan American Highway south to Chincha, and then via an unpaved road up the Topara River valley to the mine site. Internal roadways connect the various mine site components. The site is located at an average elevation of 2,000 meters above sea level.

 

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Mining Operations

 

History

 

Several companies have held interests in the Cerro Lindo mine area, including BTX, Phelps Dodge, and Nexa Peru. Exploration work completed to date includes geological mapping, rock chip and soil sampling, trenching, ground geophysical surveys, and exploration, definition and underground operational core drilling. Feasibility studies were completed in 2002 and 2005, with mine construction commencing in 2006. Formal production started in 2007, and the mine has been operational since that date.

 

Title, leases and options

 

All mineral concessions are held in the name of Nexa Peru. The tenure consists of 68 mining concessions and one beneficiation concession, totaling approximately 43,750.2 hectares.

 

Nexa Peru currently holds surface rights or easements for the following infrastructure at Cerro Lindo: mine site, access roads, power transmission line and water pipeline for the mine, old and new power transmission lines to Cerro Lindo, desalination plant, water process plant, and the water pipeline from the desalination plant to the mine site. There is sufficient suitable land available within the mineral tenure held by Nexa Peru for tailings disposal, mine waste disposal and installations such as the process plant and related mine infrastructure.

 

Cerro Lindo is not currently subject to third-party royalties. When the current tax stability agreement expires in 2021, Nexa Peru will be required to pay levies to the Peruvian government for 2022. For more information, see “Information on the Company—Regulatory matters—Peruvian regulatory framework.” As of December 31, 2020, Nexa Peru had a total of six water licenses, one for use of seawater, and the remaining five for ground water extraction.

 

Cerro Lindo holds a number of permits in support of the current operations. The permits are Directorial Resolutions issued by the Peruvian authorities upon approval of mining environmental impact assessments filed by the mining companies. Nexa Peru maintains an up-to-date record of the legal permits obtained to date.

 

Mineralization

 

Cerro Lindo is classified as a volcanogenic massive sulfide (“VMS”) deposit. The Cerro Lindo deposit is 1,500 meters long, 1,000 meters wide, and has a current vertical development of 470 meters below the surface. Mineralization consists of at least 10 discrete mineralized zones. The Cerro Lindo deposit comprises lens-shaped massive bodies, composed of pyrite (50.0% to 90.0%), yellow sphalerite, brown sphalerite, chalcopyrite, and minor galena. Significant barite is present mainly in the upper portions of the deposit. A secondary-enrichment zone, composed of chalcocite and covellite, has formed near the surface where massive sulfides have oxidized. Silver-rich powdery barite remains at the surface as a relic of sulfide oxidation and leaching.

 

During 2020, we completed approximately 60.4 km of diamond drilling, divided between exploration and infill drilling. By the end of 2020, we drilled 23.2 km in 62 drill holes from underground for the exploratory program. The brownfield drilling program confirmed the continuity of the northwest mineralization of the orebody OB-13 and the continuity of mineralization in the upper zones of northwest and southeast extensions of the orebody OB-5B. In OB-14 mineralization was confirmed between mine levels 1,800 and 1,900 and showed continuity to the southeast. These bodies are located in the mineralized volcanic system and all of our newly discovered mineralizations are currently located in the south of the Topará River.

 

During 2021, we expect to complete a total of 35.1 km of exploratory drilling. Our objective is to continue the exploratory drilling program towards the OB-14, OB-8, OB-9, OB-6 and OB-12 projections to determine the continuity of the orebody deposits. In addition, in March 2021, we intend to start the underground drilling of Pucasalla Este and Patahuasi-Millay targets and the surface drilling program at the Pucasalla target.

 

In 2020, we spent US$4.1 million in exploration expenses for Cerro Lindo, primarily associated with diamond drilling, geochemistry analysis and geological research works. We have budgeted US$7.1 million for mineral exploration expenses in 2021.

 

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Mining Operations

 

For additional information, see the Technical Report Summary on Cerro Lindo, filed as Exhibit 15.1 of this annual report on Form 20-F.

 

Operations and infrastructure

 

The Cerro Lindo mine is completely mechanized, using rubber-tired equipment for all development and production operations. There is no shaft; all access is through 15 portals servicing adits, drifts and declines. Ore is extracted from nine separate ore bodies and delivered to the process plant via a series of conveyors. All ore is commingled during transport to the concentrator stockpile; ore from different ore bodies is not segregated.

 

We have completed construction of all key infrastructure required for mining and processing operations, including the underground mine, access roads, power lines, water pipelines, the desalination plant, offices and warehouses, accommodations, the process plant/concentrator, conveyor systems, waste rock facilities, temporary ore stockpiles, the paste-fill plant and the dry-stack tailings storage facilities. A new freshwater pipeline from the desalination plant on the coast to the mine was completed in February 2020 and is operational. The national grid supplies electrical power for the mine site.

 

In 2020, we spent US$26.9 million on sustaining capital expenditures for Cerro Lindo, primarily associated with mine development, equipment replacement and other major infrastructure projects.

 

Production

 

The Cerro Lindo mine is in the production stage and has a treatment plant capacity of 21,000 tonnes of ore per day. The Cerro Lindo unit has an authorized capacity of 20,000 tonnes of ore per day, but Peruvian law allows units to operate at a capacity 5.0% higher than their authorized capacity.

 

The table below summarizes the Cerro Lindo mine’s concentrate production, metal contained in concentrates produced and average grades for the periods indicated. Production in 2020 was significantly lower than 2019 due to the effects of the COVID-19 pandemic and associated production interruptions from March 18 to May 10, 2020, the period in which mandatory lockdown measures were in place. For more information on the impact of the COVID-19 pandemic on Nexa’s operations, see “Risk Factors—Global or regional health considerations, including the outbreak of a pandemic or contagious disease, such as the ongoing COVID-19 pandemic, have had and could continue to have adverse effects on our business, financial condition and results of operations,” “Operating and Financial Review and Prospects—Overview—Executive Summary” and “Operating and Financial Review and Prospects—Overview—Key factors affecting our business and results of operations—COVID-19.”

 

    For the Year Ended December 31,  
    2020     2019     2018  
Treatment ore (in tonnes)     5,482,211       6,799,747       6,914,653  
Average ore grade                        
Zinc (%)     1.93       2.05       2.07  
Copper (%)     0.59       0.64       0.64  
Lead (%)     0.29       0.25       0.25  
Silver (ounces per tonne)     0.78       0.69       0.69  
Gold (ounces per tonne)     0.003       0.002       0.002  
Metal contained in concentrates production                        
Zinc (in tonnes)     95,426       126,310       130,349  
Copper (in tonnes)     27,820       37,678       38,338  
Lead (in tonnes)     11,590       12,256       12,761  
Silver (in oz)     2,938,985       3,250,479       3,343,551  
Gold (in oz)     4,020       4,458       4,129  
Cash Cost, net of by-product credits (in US$/t)     (8.7 )     356.0       (50.4 )
Cash Cost, net of by-product credits (in US$/lb)     (0.4 )     0.16       (0.02 )
Capital Expenditures (in millions of US$)     27.7       50.5       25.9  

 

 

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Mining Operations 

 

Mineral Reserves and Mineral Resources

 

Cerro Lindo – Year End Mineral Reserves as of December 31, 2020

 

                  Grade     Contained Metal  
Ownership         Tonnage     Zinc     Copper     Silver     Lead     Gold     Zinc     Copper     Silver     Lead     Gold  
(%)(2)     Class     (Mt)     (%)     (%)     (g/t)     (%)     (g/t)     (kt)     (kt)     (koz)     (kt)     (koz)  
          Proven       29.37       1.71       0.60       20.9       0.23       -       501.5       177.3       19,702       66.1       -  
                                                                                                     
  80.16 %     Probable       22.73       1.08       0.62       21.5       0.18       -       246.4       141.8       15,770       40.0       -  
                                                                                                     
          Subtotal       52.10       1.44       0.61       21.2       0.20       -       747.9       319.1       35,472       106.1       -  

Notes:

1. Subpart 1300 of Regulation S-K definitions were followed for Mineral Reserves, which also are consistent with the CIM (2014) definitions.
2. Mineral Reserves data presented in this table represents 100% of the Mineral Reserves estimates for the property. Please refer to our ownership percentage for the amounts attributable to our ownership interest in the property.
3. Numbers may not add due to rounding.
4. The qualified person for mineral reserves is SLR Consulting, an independent mining consulting firm.

 

The Cerro Lindo Mineral Reserves estimates in the table above are based on costs and modifying factors from the Cerro Lindo mine. Mining methods include sub-level open stoping (“SLS”) for the majority of the Mineral Reserves, and some sill pillar recovery using cut and fill (“C&F”) methods. Mineral Reserves were reported using NSR cut-off values of US$33.56/t processed for SLS and US$49.90/t processed for C&F, respectively. A number of incremental stopes (down to US$26.16/t NSR value) are included in the estimate. A minimum mining width of 5.0 and 4.0 meters was used for SLS and C&F methods, respectively, inclusive of recovery losses and dilution. The net smelter return (“NSR”) cut-off value is determined using the mineral reserve metal prices, metal recoveries, concentrate transport, treatment and refining costs, as well as mine operating costs. Metal prices used for mineral reserves are based on consensus, long term forecasts from banks, financial institutions and other sources. Mineral reserves are estimated using average long-term metal prices of zinc: US$2,494.90/t (US$1.13/lb); lead: US$1,956.00/t (US$0.89/lb); copper: US$6,457.90/t (US$2.93/lb) and silver: US$16.85/oz. The current LOM plan continues to 2029.

 

For more information, see Section 12 of our Technical Report Summary for Cerro Lindo filed as Exhibit 15.1 of this annual report on Form 20-F.

 

Cerro Lindo – Net Difference in Mineral Reserves between December 31, 2020 versus December 31, 2019

 

                Contained Metal      
       

Tonnage 

    Zinc     Copper     Silver     Lead   Gold  
 Ownership (%)(1)      Class     (Mt)     (kt)     (kt)     (koz)     (kt)   (koz)  
          Proven       +7.85       +171.5       +41.9       +6,530       +26.0      
                                                         
  80.16 %     Probable       -4.12       -35.0       -37.7       -387       +2.4      
                                                         
          Subtotal       +3.73       +136.5       +4.2       +6,143       +28.4      
(1) The information presented in this table includes 100% of the mineral reserves estimates for the property. Please refer to our ownership percentage for the amounts attributable to our ownership interest in the property.

 

Overall, Cerro Lindo’s mineral reserves have increased, mainly due to the addition of new mineralization domains as a result of exploration diamond drilling, improvement in mineral resources estimates, improvements on mining constraints and slightly lower marginal NSR cut-off values. For more information, see Sections 11 and 12 of our Technical Report Summary for Cerro Lindo filed as Exhibit 15.1 of this annual report on Form 20-F.

 

44

 

 

Mining Operations

 

Cerro Lindo – Year End Mineral Resources as of December 31, 2020

 

            Grade     Contained Metal  
Ownership          

Tonnage 

    Zinc     Copper     Silver     Lead     Gold     Zinc     Copper     Silver     Lead     Gold  
(%)(2)      Class     (Mt)     (%)     (%)     (g/t)     (%)     (g/t)     (kt)     (kt)     (koz)     (kt)     (koz)  
          Measured       4.40       2.00       0.67       19.6       0.20       -       87.8       29.4       2,774       8.9       -  
                                                                                                     
      Indicated       3.46       1.37       0.45       25.0       0.25       -       47.3       15.5       2,776       8.8       -  
  80.16 %                                                                                                
          Subtotal       7.86       1.72       0.57       22.0       0.22       -       135.1       44.9       5,550       17.6       -  
                                                                                                     
          Inferred       8.71       1.28       0.33       31.2       0.35       -       111.1       29.1       8,748       30.6       -  

Notes:

1. Subpart 1300 of Regulation S-K definitions were followed for Mineral Resources, which also are consistent with the CIM (2014) definitions.
2. Mineral Resources data presented in this table represents 100% of the Mineral Resources estimates for the property. Please refer to our ownership percentage for the amounts attributable to our ownership interest in the property.
3. Mineral Resources are reported exclusive of those mineral resources that were converted to mineral reserves, and mineral resources are not mineral reserves and do not have demonstrated economic viability.
4. Numbers may not add due to rounding.
5. The qualified person for mineral resources is SLR Consulting, an independent mining consulting firm.

 

The Cerro Lindo Mineral Resources estimates in the table above were completed using Datamine Studio RM (“Datamine”) and Seequent’s Leapfrog Geo (“Leapfrog”) software. Wireframes for geology and mineralization were constructed in Leapfrog based on geology sections, assay results, lithological information, underground mapping and structural data. Assays were capped to various levels based on exploratory data analysis and then composited to 2.5 m lengths. Wireframes were filled with blocks sub-celled at wireframe boundaries. Blocks were interpolated with grade using the ordinary kriging (“OK”) and inverse distance cubed (“ID3”) interpolation algorithms. Block estimates were validated using industry standard validation techniques. Classification of blocks used distance-based and other criteria. The Cerro Lindo Mineral Resources estimates were reported using all the material within resource shapes generated in Deswik Stope Optimizer (“DSO”) software. The estimate satisfied the minimum mining width of 5.0 m and 4.0 m for SLS and C&F for resource shapes respectively, and used NSR cut-off value of US$33.56/t for SLS and US$49.90/t for C&F. NSR cut-off values for Cerro Lindo’s Mineral Resources estimate are based on an average long-term zinc price of US$2,869.14/t (US$1.30/lb), a lead price of US$2,249.40/t (US$1.02/lb), a copper price of US$7,426.59/t (US$3.37/lb) and a silver price of US$19.38/oz.

 

For more information, see Section 11 of our Technical Report Summary for Cerro Lindo filed as Exhibit 15.1 of this annual report on Form 20-F.

 

Vazante

 

Location and means of access

 

The Vazante mine is an underground and open pit, polymetallic mine located about 8.5 km from the municipality of Vazante, in the state of Minas Gerais, Brazil. The project area has elevations ranging from 690 to 970 meters above sea level. Access from Brasilia is via federal highway BR-040 toward Paracatu. Internal roadways connect the various mine-site components. Concentrates are trucked about 250 km to the Três Marias smelter. The closest commercial airport is located in Brasilia. The Vazante municipal airport for light aircraft is adjacent to the mine site.

 

History

 

Mineralization was initially exploited by artisanal miners during the 1950s. Mechanized open pit mining and underground mining commenced in 1969 and 1983, respectively. The current primary ore types mined are hydrothermal zinc silicates and willemite. Initial mining operations exploited supergene calamine ores and a mixture of the zinc secondary minerals hemimorphite and smithsonite, which are derived from the weathering of silicate ore.

 

45

 

 

Mining Operations

 

Title, leases and options

 

Nexa Brazil owns 100.0% of the Vazante project. Mineral concessions are divided into core tenements, where the known mineral deposits are located and where we have active mining operations, and the surrounding exploration concessions. Nexa Brazil holds two mining concessions and one group of mining concessions in the core area that have a total area of 2,091.1 hectares. The group of mining concessions comprises six mining concessions, totalling an area of 819.5 hectares. The mineral reserves and resources are located within the limits of seven mining concessions with an area of 1,864.6 hectares, which host the active mining operations. One mining concession (tenement # 14.840/1967), which is part of the group of mining concessions, has a potential to host zinc and lead mineralization, however it does not yet have associated mineral reserves and resources.

 

Nearby the main area, Nexa Brazil also holds 62 exploration licenses totalling 50,076.8 hectares, two rights to apply for mining concession totalling 374.2 hectares, one mining application totalling 190.0 hectares and one mining concession application totalling 52.5 hectares, in addition to the core tenements.

 

Nexa Brazil holds surface rights sufficient to support the current operations. Some surface rights agreements require annual payments to the owners. Three easements have been granted in support of the mining activities. There is sufficient suitable land available within the mineral tenure held by Nexa Brazil for tailings disposal, mine waste disposal, and installations such as the process plant and related mine infrastructure.

 

Brazilian companies that hold mining concessions are subject to a royalty payment imposed by the National Mining Agency. For more information, see “Information on the Company—Regulatory matters—Brazilian regulatory framework—Royalties and other taxes on mining activities.”

 

Nexa Brazil holds nine licenses for water management and water use in the operations. Nexa Brazil has lodged renewal applications, where applicable, for the water management.

 

The Vazante Operation holds several permits in support of the current operations. The main instrument to regulate the Vazante Operation is a set of operating licenses issued by the COPAM from the state of Minas Gerais. The licenses are active, some of them under renewal process.

 

Mineralization

 

The Vazante and Extremo Norte zinc deposits are epigenetic zinc silicate deposits, and Vazante is one of the largest deposits of its type worldwide. Mineralization exists within a sequence of pelitic carbonate rocks belonging to the Serra do Poço Verde formation of the Vazante group. The major structural control is the Vazante fault.

 

We are conducting ongoing tests to explore extensions of known mineralization, infilling areas where no data are currently available, and identifying other areas where mineralization may be present. Examples of exploration successes using these methods within the Vazante mine area include our projects Lumiadeira, Ramp 29, and Deep Exploration.

 

In 2020, we completed approximately 4.6 km of diamond drilling, divided between exploratory and brownfield drilling. The focus was on the extension of the Vazante mine ore bodies, exploring the targets Lumiadeira, Extremo Norte and shallow calamine mineralization in the Extremo Norte area. In addition, drilling activity confirmed the presence of Pink Dolomite, a typical host rock of Vazante Ore and Sungem Target. Exploratory drill holes intersected occurrences of sphalerite in a hydrothermal breach with white dolomite.

 

In 2020, we spent US$0.8 million on brownfield projects for life of mine extension, including exploration project maintenance and geological activities. In 2020, we drilled 13 exploration drill holes, totaling 4.6 km. We have budgeted US$1.7 million for the project during 2021 and we expect to drill 10.5 km.

 

We also performed 324 diamond drill holes, totaling 46.1 km aimed mineral resources classification in the Vazante mine. The focus of this campaign was north of Extremo Norte and south of Lumiadeira.

 

46

 

 

Mining Operations

 

Operations and infrastructure

 

The Vazante operation consists of two mechanized underground mines, the Vazante Mine and Extremo Norte Mine, currently operating at a rate of approximately 1.5 Mtpy. Production drilling operations have been performed by company personnel using a variety of drilling machines throughout the history of the Vazante mine.

 

The Vazante underground mine has been in operation since 1983 and is a fully mechanized mine using rubber-tired diesel equipment for development and production activities. Access is through two portals for Vazante and one portal for Extremo Norte. As development progresses at Extremo Norte, a connecting drift will be established from Vazante to Extremo Norte.

 

All infrastructure required for the current mining and processing operations has been constructed and is operational. This includes the underground mines, access roads, power lines, water pipelines, offices and warehouses, a process plant/concentrator, conveyor systems, waste rock facilities, temporary ore stockpiles, paste-fill plants, and tailings storage facilities.

 

The power supply to the Vazante operation is provided by two independent 138 kV transmission lines that feed the site and that can provide up to 55 MW. There are two 23/40 MVA transformers in the surface substation at the Vazante Operation and power is distributed to other areas of the mine at 13.8 kV and 440 V via transformer secondaries to power mine equipment. The power demand by 2026 is expected to reach approximately 46 MW as dewatering demands continue to grow. A new transmission line from Paracatu to Vazante of 60 MW capacity is under construction by Companhia Energética de Minas Gerais S.A (“CEMIG”) and is expected to be completed in March 2021. There are two 700 kVA diesel generators on site to provide backup power in case of main line interruption. The price of electrical energy is budgeted at R$0.288/kWh for 2021.

 

In 2020, we spent US$21.9 million on sustaining capital expenditures for this property, primarily associated with mine development, equipment replacement and other major infrastructure. In addition, we invested US$13.0 million in capital expenditures related to the Vazante mine deepening, focusing on expansion. For more information, see “Information on the Company—Mining Operations—Growth Projects—Vazante mine deepening project.”

 

In March 2021, during a regular inspection of the Extremo Norte mine in Vazante, we identified that the area around the main access and the escape route of the mine presented above-normal ground displacements. The Extremo Norte mine requires dewatering of the aquifer for its operations, which leads to depressurization and may cause local disturbances in the rock mass around the mine. As a preventive measure, activities in this area have been temporarily suspended. The Nexa team, supported by outside experts, is conducting a detailed analysis of the geological and geotechnical conditions in order to ensure the safety of workers and the resumption of mine activities.

 

Production

 

The Vazante mine is in the production stage and has a treatment plant with a nominal design processing capacity of approximately 4,400 tonnes of ore per day. The table below summarizes the Vazante mine’s concentrate production, metal contained in concentrates produced and average grades for the periods indicated.

 

   

For the Year Ended December 31, 

 
    2020     2019     2018  
Treatment ore (in tonnes)     1,622,927       1,407,199       1,374,380  
Average ore grade                        
Zinc (%)     10.43       11.45       12.13  
Lead (%)     0.36       0,31       0.34  
Silver (ounces per tonne)     0.63       0.57       0.62  
Metal contained in concentrate production                        
Zinc (in tonnes)     147,990       139,041       140,842  
Lead (in tonnes)     1,333       1,015       1,180  
Silver (in oz)     383,509       333,141       380,190  
Cash cost, net of by-product credits (in US$/t)     1,180.6       1,138.5       834.5  
Cash cost, net of by-product credits (in US$/lb)     53.6       0.52       0.38  
Capital Expenditures (in millions of US$)     37.6       70.0       89.9  

 

47

 

 

Mining Operations

 

Mineral Reserves and Mineral Resources

 

Vazante – Year End Mineral Reserves as of December 31, 2020

 

                  Grade     Contained Metal  
 Ownership        

Tonnage 

    Zinc     Copper     Silver     Lead     Gold     Zinc     Copper     Silver     Lead     Gold  
(%)      Class     (Mt)     (%)     (%)     (g/t)     (%)     (g/t)     (kt)     (kt)     (koz)     (kt)     (koz)  
          Proven       8.44       8.40             15.2       0.24             708.8             4,125       20.6        
                                                                                                     
  100 %     Probable       8.24       8.83             12.2       0.21             727.9             3,241       17.4        
                                                                                                     
          Subtotal       16.68       8.61             13.7       0.23             1,436.7             7,367       38.0        

Notes:

1. Subpart 1300 of Regulation S-K definitions were followed for Mineral Reserves, which also are consistent with the CIM (2014) definitions.
2. Numbers may not add due to rounding.
3. The qualified person for Mineral Reserves is SLR Consulting, an independent mining consulting firm.

 

The Vazante Mineral Reserves estimates in the table above consider actual costs and modifying factors from the Vazante mine, as well as operational level mine planning and budgeting. The dilution that has been applied is related to the selected mining method. The two main mining methods are sublevel open stoping (“SLOS”) and vertical retreat mining (“VRM”). The Vazante Mineral Reserves are estimated at a NSR cut-off value of US$47.49/t processed. The NSR cut-off value was determined using the mineral reserve metal prices, metal recoveries, transport, treatment and refining costs, as well as mine operating costs. A minimum mining width of 4.0 m was applied and average bulk density of 3.1 t/m3. Mineral reserves are estimated using average long-term metal prices of zinc: US$2,494.90/t (US$1.13/lb); lead: US$1,956.00/t (US$0.89/lb); silver: US$16.85/oz (using an average long term U.S. dollar to Brazilian real exchange rate of 4.84), and metallurgical recoveries are based on recovery curves derived from historical processing data. Long-term metal prices used for mineral reserves are based on consensus and long term forecasts from banks, financial institutions and other sources. The current LOM plan continues to 2031.

 

For more information, see Section 12 of our Technical Report Summary for Vazante filed as Exhibit 15.3 of this annual report on Form 20-F.

 

Vazante – Net Difference in Mineral Reserves between December 31, 2020 versus December 31, 2019

 

                  Contained Metal      
       

Tonnage 

    Zinc     Copper     Silver     Lead   Gold  
Ownership (%)(1)     Class     (Mt)     (kt)     (kt)     (koz)     (kt)   (koz)  
          Proven       -0.03       -71.7             +52       -3.6      
                                                       
  100 %     Probable       -0.84       -86.4             -11       -4.4      
                                                       
          Subtotal       -0.87       -158.1             +41       -8.0      
(1) The information presented in this table includes 100% of the mineral reserves estimates for the property.

 

Overall, as of December 31, 2020 the Mineral Reserves of Vazante have decreased mainly due to depletion through mining. For more information, see Sections 11 and 12 of our Technical Report Summary for Vazante filed as Exhibit 15.3 of this annual report on Form 20-F.

 

48

 

 

Mining Operations

 

Vazante – Year End Mineral Resources as of December 31, 2020

 

                  Grade     Contained Metal  
Ownership         Tonnage     Zinc     Copper     Silver     Lead     Gold     Zinc     Copper     Silver     Lead     Gold  
(%)     Class     (Mt)     (%)     (%)     (g/t)     (%)     (g/t)     (kt)     (kt)     (koz)     (kt)     (koz)  
          Measured       3.40       6.91             8.4       0.18             235.0             918       6.2        
                                                                                                     
      Indicated       2.88       6.84             5.6       0.14             196.8             522       4.0        
  100 %                                                                                                
          Subtotal       6.28       6.88             7.1       0.16             431.6             1,440       10.2        
                                                                                                     
          Inferred       13.85       6.86             9.5       0.18             950.1             4,217       25.6        

 

Notes:

1. Subpart 1300 of Regulation S-K definitions were followed for Mineral Resources, which also are consistent with the CIM (2014) definitions.
2. Mineral Resources are reported exclusive of those mineral resources that were converted to mineral reserves, and mineral resources are not mineral reserves and do not have demonstrated economic viability.
3. Numbers may not add due to rounding.
4. The qualified person for Mineral Resources is SLR Consulting, an independent mining consulting firm.

 

The Vazante Mineral Resources estimates in the table above were completed using Datamine and Leapfrog software. The mineral resources at Vazante comprise three styles of mineralization. The first style of mineralization is represented by the hypogene (willemite) mineralized zones that are found in the underground portions of the Vazante and Extremo Norte deposits. The second style of mineralization is represented by the supergene (calamine) mineralized zones found in the Cava 3A, Matas dos Paulistas, and Braquiara areas of the Extremo Norte and Vazante deposits. This supergene (calamine) mineralization is referred to at the Vazante Operation as calamine mineralization and comprises a mixture of smithsonite and hemimorphite minerals. The third type of mineralization comprises tailings that are contained within the Aroeira TSF. The material found in the Aroeira tailings comprise a mixture of hypogene (willemite) and supergene (calamine) minerals. The Mineral Resource statements for the underground hypogene (willemite) mineralization are prepared within reporting panels prepared using the native functions and workflows available through the Deswik mine modelling software package considering spatial continuity, a minimum width of three meters and a NSR cut-off value of US$47.49/t for SLS and US$74.96/t for run and pillar (“R&P”). The Mineral Resource estimates for the supergene (calamine) mineralization are prepared using an open pit shell that considers appropriate metal prices, mining costs, metallurgical recoveries and geotechnical considerations. The Mineral Resources are estimated at an NSR cut-off value of US$20.16/t for soil and US$20.02/t for fresh rock and transition material. The Mineral Resource statements for the tailings at Vazante are reported considering the material with an NSR value of greater than US$20.62/t which lies above the original topographic surface. All NSR cut-off values for Mineral Resources at Vazante are estimated using average long-term metal prices of zinc: US$2,869.14/t (US$1.30/lb), lead: US$ 2,249.40/t (US$1.02/lb) and silver: US$19.38/oz (using an average long-term U.S. dollar to Brazilian real exchange rate of 4.84), and metallurgical recoveries are based on recovery curves derived from historical processing data.

 

For more information, see Section 11 of our Technical Report Summary for Vazante filed as Exhibit 15.3 of this annual report on Form 20-F.

 

El Porvenir

 

Location and means of access

 

The El Porvenir mine is an underground, polymetallic mine located in the district of San Francisco de Asís de Yarusyacán, in the province of Pasco, Peru. The property is located in the central Andes mountains region of Peru, at approximately 4,200 meters above sea level. The mine is situated at kilometer 340 of the Carretera Central Highway (Lima—Huánuco route), 13 km from the city of Cerro de Pasco. The mine is located in the Central Cordillera zone, which contains the communities of Parán, Lacsanga and Santo Domingo de Apache.

 

History

 

The El Porvenir mine began its operation as small-scale artisanal mine in 1949. We have been investing in the mine since then and, in 2012, production reached its current capacity of 6,500 tonnes per day. In 2013, we commenced the integration process with the Atacocha mine. In 2015, El Porvenir tailings deposit was integrated with Atacocha’s. In 2016, we worked on integrating the energy supply between the two mines. In 2019, the two underground mines were connected allowing us to initiate an exploration program in the integration area. In 2020, in response to COVID-19 and based on our cost management strategy, the integration process was temporarily suspended and Atacocha’s underground operations were not resumed after the mandatory restriction period from the Peruvian Government was lifted in June. For additional information on the integration of the El Porvenir and Atacocha mines, see “Information on the Company—Mining operations—Growth projects—Pasco mining complex” below.

 

49

 

 

Mining Operations

 

Title, leases and options

 

The El Porvenir mine is owned by Nexa Resources El Porvenir S.A.C., a subsidiary of Nexa Peru in which Nexa Peru has a 99.99% equity interest.

 

The El Porvenir mine has a total of 25 concessions covering approximately 4,846.8 hectares, as well as a beneficiation plant, “Acumulacion Aquiles 101.” With respect to the surface property at El Porvenir project, there is a mining site of 450.8 hectares, where the mining concession is located, as well as additional surface property where tailings dams/ponds, camps sites and other ancillary infrastructure are located.

 

Mining operations at the El Porvenir mine are subject to certain royalties payable by Nexa Resources El Porvenir S.A.C. For more information, see “Information on the Company—Regulatory matters—Peruvian regulatory framework—Royalties and other taxes on mining activities.”

 

The El Porvenir Mine holds a number of permits in support of the current operations. The permits are Directorial Resolutions issued by the Peruvian authorities upon approval of mining environmental management instruments filed by the mining companies. Nexa Peru maintains an up-to-date record of the legal permits obtained to date.

 

Mineralization

 

The El Porvenir mine is a typical skarn deposit. The mineralization occurs within the contact of the upper Triassic limestone (i.e., exoskarn) and the granodioritic-dacitic intrusive rocks (i.e., endoskarn). There are also recognized veins and replacement manto type, minor disseminated mineralization may occur within the intrusive units. West of the Milpo-Atacocha fault within the Goyllarisquizga Group, mineralization is characterized as veins and disseminations.

 

Four groups of vein/mineralized structures are reported. Structurally controlled veins are sub-vertical up to 150 meters long, with a vertical extent of 350 meters. Economic mineralogy is mostly comprised of galena, sphalerite, and tetrahedrite, as well as variable and lesser pyrite, quartz and rhodochrosite.

 

In 2020, we completed approximately 37.6 km of diamond drilling, divided between exploratory and infill drilling. The 2020 exploration program at El Porvenir was directed to increasing mineral resources, drilling the high-altitude zones of the mine (above the 3,700 meter level) and looking for new mineralized zones. The exploration program identified silver, lead, zinc and gold mineralization along the strike, based on the surface and underground drilling program in the target Sara, which is open for expansion.

 

We spent approximately US$2.7 million on the El Porvenir brownfield project in 2020, including in exploration project maintenance and geological activities. In 2020, we drilled 42 drill holes totaling 16.1 km at El Porvenir. We have budgeted US$3.2 million for the project during 2021 and we expect to drill 18.0 km.

 

For additional information, see the Technical Report Summary on El Porvenir, filed as Exhibit 15.2 of this annual report on Form 20-F.

 

50

 

 

Mining Operations

 

Operations and infrastructure

 

Most of the exploration is generally conducted simultaneously with underground development, which involves diamond core drilling and channel sampling following underground drifting.

 

The El Porvenir project site consists of an underground mine, tailings pond, waste rock stockpiles, a process facility with associated laboratory and maintenance facilities and maintenance buildings for underground and surface equipment. Facilities and structures include a warehouse, office, change house facilities, main shaft, ventilation shaft, backfill plant, explosives storage area, hydroelectric power generation, power lines and substation, fuel storage tanks, a warehouse and laydown area and a permanent accommodation camp.

 

The electrical power supply for the project comes from two sources: connection to the SEIN national power grid by a main substation located near the site, and the Candelaria Hydro, which consists of three turbines connected to the project through the main substation by a transmission line. All other loads of the project are fed from the main substation through overhead power lines. These power lines are used to deliver power to various locations to support activities during operation of the mine.

 

Site roads include main roads suitable for use by mining trucks that transport concentrates to Lima and service roads for use by smaller vehicles. The site roads are used by authorized mine personnel and equipment, with access controlled by Nexa Peru. An approximately 15 to 20 kilometer network of service roads was constructed to provide access to the underground mine, processing plant, tailings facility, waste rock stockpile, mine offices, workshops, mine camps and other surface infrastructure.

 

In 2020, we spent US$13.0 million on sustaining capital expenditures for this property, primarily associated with mine development, equipment replacement and other major infrastructure.

 

Production

 

The El Porvenir mine is in the production stage and has a treatment plant capacity of 6,500 tonnes of ore per day. The table below summarizes the El Porvenir mine’s concentrate production, metal contained in concentrates produced and average grades for the periods indicated. Production in 2020 was significantly lower than in 2019 due to the economic effects of the COVID-19 pandemic and related production interruptions from March to May 2020. For more information on the impact of the COVID-19 pandemic on Nexa’s operations, see “Risk Factors—Global or regional health considerations, including the outbreak of a pandemic or contagious disease, such as the ongoing COVID-19 pandemic, have had and could continue to have adverse effects on our business, financial condition and results of operations,” “Operating and Financial Review and Prospects—Overview—Executive Summary” and “Operating and Financial Review and Prospects—Overview—Key factors affecting our business and results of operations—COVID-19.”

 

    For the Year Ended December 31,  
    2020     2019     2018  
Treatment ore (in tonnes)     1,502,618       2,120,765       2,149,927  
Average ore grade                        
Zinc (%)     2.65       2.92       3.04  
Copper (%)     0.17       0.15       0.15  
Lead (%)     0.93       1.01       0.98  
Silver (ounces per tonne)     2.00       2.08       1.92  
Gold (ounces per tonne)     0.01       0.02       0.01  
Metal contained in concentrate production                        
Zinc (in tonnes)     34,867       54,689       57,872  
Copper (in tonnes)     334       465       567  
Lead (in tonnes)     10,858       16,914       16,641  
Silver (in oz)     2,315,181       3,412,656       2,533,801  
Gold (in oz)     5,899       11,191       9,664  
Cash Cost, net of by-product credits (in US$/t)     1,338.0       1,372.9       1,192.9  
Cash Cost, net of by-product credits (in US$/lb)     60.7       0.62       0.54  
Capital Expenditures (in millions of US$)     12.9       32.9       25.6  

 

51

 

 

Mining Operations

 

Mineral Reserves and Mineral Resources

 

El Porvenir – Year End Mineral Reserves as of December 31, 2020

 

                  Grade     Contained Metal  
Ownership        

Tonnage 

    Zinc     Copper     Silver     Lead     Gold     Zinc     Copper     Silver     Lead     Gold  
  (%)(2)      Class     (Mt)     (%)     (%)     (g/t)     (%)     (g/t)     (kt)     (kt)     (koz)     (kt)     (koz)  
          Proven       3.76       3.76       0.25       62.9       0.98       -       141.3       9.5       7,602       36.9       -  
                                                                                                     
  80.16 %     Probable       10.09       3.74       0.22       62.8       0.85       -       377.6       22.4       20,364       85.5       -  
                                                                                                     
          Subtotal       13.85       3.75       0.23       62.8       0.88       -       518.9       31.9       27,966       122.4       -  

Notes:

1. Subpart 1300 of Regulation S-K definitions were followed for Mineral Reserves, which also are consistent with the CIM (2014) definitions.
2. Mineral Reserves data presented in this table represents 100% of the mineral reserves estimates for the property. Please refer to our ownership percentage for the amounts attributable to our ownership interest in the property.
3. Numbers may not add due to rounding.
4. The qualified person for Mineral Reserves is SLR Consulting, an independent mining consulting firm.

 

The El Porvenir Mineral Reserves estimates in the table above were prepared using DSO, mine design and scheduling software. Mining methods used are C&F mining, using unconsolidated rock fill and hydraulic backfill, and SLS using unconsolidated rock fill. NSR values were calculated using mineral reserve metal prices, metallurgical recovery and consideration of smelter terms, including revenue from payable metals, price participation, penalties, smelter losses, transportation, treatment, refining and sales charges. Production stope shapes for C&F and SLS mining methods use only measured and indicated mineral resources, satisfy minimum mining widths of 5.0 m independent of the mining method and NSR cut-off values that are calculated per zone and mining method. For the C&F mining method, the values vary from US$59.75/t at the lower zone to US$63.37/t at the mine deepening zone. For SLS the values vary from US$56.44/t at the lower zone to US$60.06/t at the mine deepening zone. Mineral reserves were estimated as measured and indicated mineral resources contained within stope shapes and development design, and are reported inclusive of extraction losses and dilution. Mineral Reserves are estimated using average long-term metal prices of zinc: US$2,494.90/t (US$1.13/lb); lead: US$1,956.00/t (US$0.89/lb); copper: US$6,457.90/t (US$2.93/lb) and silver: US$16.85/oz, metallurgical recoveries are based on recovery curves derived from historical processing data.

 

For more information, see Section 12 of our Technical Report Summary for El Porvenir filed as Exhibit 15.2 of this annual report on Form 20-F.

 

El Porvenir – Net difference in Mineral Reserves between December 31, 2020 versus December 31, 2019

 

                  Contained Metal    
       

Tonnage 

    Zinc     Copper     Silver     Lead  

Gold

Ownership (%)(1)     Class     (Mt)     (kt)     (kt)     (koz)     (kt)   (koz)
          Proven       -3.23       -104.3       -5.2       -4,155       -20.5    
                                                       
  80.16 %     Probable       +0.87       +23.5       -0.1       +7,702       +20.8    
                                                       
          Subtotal       -2.36       -80.7       -5.4       +3,547       +0.3    

 

(1) The information presented in this table includes 100% of the Mineral Reserves estimates for the property. Please refer to our ownership percentage for the amounts attributable to our ownership interest in the property.

 

Overall, as of December 31, 2020 the Mineral Reserves of El Porvenir are lower than the Mineral Reserves for the same period in 2019. The differences are primarily due to a better understanding of mining constraints and non-recoverable areas, decrease tonnage in model due to reinterpretation and higher cut-off values. For more information, see Sections 11 and 12 of our Technical Report Summary for El Porvenir filed as Exhibit 15.2 of this annual report on Form 20-F.

 

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Mining Operations

 

El Porvenir – Year End Mineral Resources as of December 31, 2020

 

                  Grade     Contained Metal  
Ownership         Tonnage     Zinc     Copper     Silver     Lead     Gold     Zinc     Copper     Silver     Lead     Gold  
(%)(2)     Class     (Mt)     (%)     (%)     (g/t)     (%)     (g/t)     (kt)     (kt)     (koz)     (kt)     (koz)  
          Measured       0.23       2.59       0.23       63.5       0.99       -       6.0       0.5       471       2.3       -  
                                                                                                     
      Indicated       1.33       2.93       0.20       63.3       0.89       -       39.0       2.6       2,715       11.9       -  
  80.16 %                                                                                                
          Subtotal       1.56       2.87       0.20       63.4       0.91       -       45.0       3.2       3,186       14.2       -  
                                                                                                     
          Inferred       8.47       3.60       0.23       78.4       0.95       -       305.0       19.8       21,345       80.8       -  

 

Notes:

1. Subpart 1300 of Regulation S-K definitions were followed for Mineral Resources, which also are consistent with the CIM (2014) definitions.
2. Mineral Resources data presented in this table represents 100% of the mineral resources estimates for the property. Please refer to our ownership percentage for the amounts attributable to our ownership interest in the property.
3. Mineral Resources are reported exclusive of those mineral resources that were converted to mineral reserves, and mineral resources are not mineral reserves and do not have demonstrated economic viability.
4. Numbers may not add due to rounding.
5. The qualified person for Mineral Resources is SLR Consulting, an independent mining consulting firm.

 

The El Porvenir Mineral Resources estimates in the table above were completed using Datamine and Leapfrog software. Wireframes for geology and mineralization were constructed in Leapfrog based on geology sections, assay results, lithological information, underground mapping and structural data. Assays were capped to various levels based on exploratory data analysis and then composited to 2.0 m lengths. Wireframes were filled with blocks and sub-celling at wireframe boundaries. Blocks were interpolated with grade using OK and ID3 interpolation algorithms. Block estimates were validated using industry standard validation techniques. Classification of blocks used distance-based and mineralization continuity criteria. The Mineral Resources in El Porvenir are contained in four zones: (i) zona alta (upper zone), (ii) zona intermedia (intermediate zone), (iii) zona Baja (lower zone) and (iv) profundizacion zona (mine deepening zone). Mineral Resources at El Porvenir underground mines are reported using all the material within resource shapes generated in DSO software, satisfying minimum mining size and continuity criteria, and using NSR cut-off values of US$60.06/t for the upper zone, US$61.09/t for the intermediate zone, US$59.75/t for the lower zone and US$63.37/t for the mine deepening zone for C&F resource shapes. A minimum mining width of 4.0 m was used for C&F resource shapes. NSR cut-off values for El Porvenir’s mineral resources estimates are based on an average long-term zinc price of US$2,869.14/t (US$1.30/lb), a lead price of US$2,249.40/t (US$1.02/lb), a copper price of US$7,427.59/t (US$3.37/lb) and a silver price of US$19.38/oz.

 

For more information, see Section 11 of our Technical Report Summary for El Porvenir filed as Exhibit 15.2 of this annual report on Form 20-F.

 

Atacocha

 

Atacocha is a polymetallic underground and open pit mine located in the district of San Francisco de Asís de Yarusyacán, in the province of Pasco, Peru.

 

The Atacocha mine is owned by Nexa Resources Atacocha S.A.A., which is controlled by Nexa Peru.

 

The Atacocha mine has a total of 147 concessions covering approximately 2,872.5 hectares, as well as a beneficiation plant, “Chicrin N° 2.” With respect to the surface property at the Atacocha project, there is a mining site of 1,343.0 hectares, where the mining concession is located, as well as additional surface property where tailings dams/ponds, camps sites and other ancillary infrastructure are located. There are royalties payable in respect of mining operations at the Atacocha project for the mining concessions held by Nexa Resources Atacocha S.A.A. For more information, see “Information on the Company—Regulatory matters—Peruvian regulatory framework—Royalties and other taxes on mining activities.”

 

The Atacocha mine holds a number of permits in support of the current operations. The permits are Directorial Resolutions issued by the Peruvian authorities upon approval of mining environmental management instruments filed by the mining companies. Nexa Peru maintains an up-to-date record of the legal permits obtained to date.

 

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Mining Operations

 

Atacocha operates two mines: the Atacocha underground mine and the San Gerardo open pit mine. As discussed below under “—Production”, the underground mine is currently suspended, but mining continues in the San Gerardo open pit mine. Both mining operations feed the Atacocha processing plant.

 

In 2020, we spent US$15.2 million on sustaining capital expenditures for this property, primarily associated with mine development, equipment replacement and other major infrastructure.

 

Mineralization Developments

 

In 2020, we completed approximately 20.9 km of diamond drilling, divided between exploratory and infill drilling. The 2020 exploration program at Atacocha was focused on increasing mineral resources in the high and low-altitude zones of the mine (at the 3,300 meter level) and finding new mineralized zones. The drilling program identified zinc, lead, copper, silver, and gold mineralization along the strike of Veta 27, which is open for expansion.

 

We spent approximately US$0.9 million on the Atacocha brownfield project in 2020, including exploration project maintenance and geological activities. In 2020, we drilled 9 drill holes totaling 3.4 km at Atacocha. We have budgeted US$0.5 million for the project during 2021 and we expect to drill 3.0 km of diamond drilling.

 

Atacocha does not currently have any estimated Mineral Reserves and is considered an exploration stage property under S-K 1300. Atacocha is not considered a material property for the purposes of S-K 1300.

 

Production

 

The Atacocha mine has a treatment plant capacity of 4,500 tonnes of ore per day. The table below summarizes the Atacocha mine’s concentrate production, metal contained in concentrates produced and average grades for the periods indicated. Production in 2020 was significantly lower than in 2019 due to the effects of the COVID-19 pandemic and associated production interruptions from March 2020 to June 2020. On June 8, 2020, following the Peruvian government’s decree allowing medium-sized mines to restart operations, we announced that Atacocha would resume operations at the San Gerardo open pit mine in mid-June. However, in light of the current macroeconomic environment and the uncertain time for recovery from effects of the COVID-19 pandemic, in June 2020 we decided that the higher-cost Atacocha underground mine would remain suspended due to our efforts to reduce costs and improve our operational efficiency, placing it under care and maintenance. We have not yet defined how long the underground mine’s suspension will last and the decision will depend on an improvement in the mine’s economic viability.

 

In addition, in December 2020, a local community group’s protest activities blocked road access to the Atacocha mine, leading to the temporary suspension of operations at the San Gerardo open pit mine until January 2021, when operations were resumed. In March 2021, new protest activities blocked road access to the Atacocha processing plant and, as of the date of this annual report, the San Gerardo open pit mine is temporarily suspended. Mining activities are limited to critical operations with a minimum workforce to ensure appropriate maintenance, safety and security. The Company continues to pursue active dialogue with the local community and authorities for peaceful resolution of this situation.

 

    For the Year Ended December 31,  
    2020     2019     2018  
Treatment ore (in tonnes)     1,065,363       1,505,428       1,551,472  
Average ore grade                        
Zinc (%)     1.20       1.43       1.43  
Copper (%)     0.05       0.08       0.10  
Lead (%)     1.15       1.30       1.18  
Silver (ounces per tonne)     1.39       1.52       1.42  
Gold (ounces per tonne)     0.01       0.01       0.02  
Metal contained in concentrate production                        
Zinc (in tonnes)     9,614       16,668       17,323  
Copper (in tonnes)     0       40       125  
Lead (in tonnes)     10,210       16,464       15,595  
Silver (in oz)     1,184,750       1,882,138       1,678,920  
Gold (in oz)     6,260       9,306       15,431  
Cash cost, net of by-product credits (in US$/t)     17.8       1,052.0       1,115.5  
Cash cost, net of by-product credits (in US$/lb)     0.8       0.48       0.51  
Capital Expenditures (in millions of US$)     15.3       11.8       16.9  

 

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Mining Operations

 

Morro Agudo

 

The Morro Agudo project consists of an underground mine and open pit, polymetallic mine, as well as three deposits along what is known as the Ambrosia Trend (Ambrosia Sul, Ambrosia Norte, and Bonsucesso). The Morro Agudo mine site is situated on Traíras Farm, about 45km south of the municipality of Paracatu, Brazil. The Ambrosia Trend deposits are situated about 15 to 20km northeast of Paracatu.

 

Nexa Brazil owns 100.0% of Morro Agudo. The total Morro Agudo project area is about 80 km long and 10 km wide at the widest extent and covers a significant strike extent of the lithologies that host mineralization at the Morro Agudo mine and along the Ambrosia Trend.

 

Nexa Brazil holds two granted mining concessions in the Morro Agudo mine area of approximately 827.6 hectares, with a valid mining concession application for an additional area of approximately 618.5 hectares. In the Ambrosia Trend area, Nexa Brazil has one granted mining concession (999.3 hectares), and two mining concession applications (1,496.5 hectares).

 

The Morro Agudo operation holds several permits in support of the current operations. The main instrument to regulate the operation is a set of operating licenses issued by the Environmental Agency from the state of Minas Gerais. The licenses are active, some of them under renewal process.

 

The Ambrosia mine in Morro Agudo reached the end of its life of mine during the fourth quarter of 2020 and operations were suspended due to the uncertainties associated with the geological model of the area, safety considerations and a greater movement of ore compared to the original plan. Due to the mine closure, Nexa reviewed Ambrosia’s portfolio of assets and analyzed the possibility of using these assets in other operations, such as the Bonsucesso mine, which is currently in the feasibility study phase. Since this project is still under feasibility studies, we recognized an impairment loss in the total amount of US$10 million. For more information, see Note 23(c) to our consolidated financial statements.

 

In 2020, we spent US$4.1 million on sustaining capital expenditures for this property, primarily associated with the mine development and maintenance of plant and equipment.

 

Mineralization Developments

 

Exploration activities conducted to date have included geological mapping; rock chip, pan concentrate, stream sediment, and soil sampling; airborne and ground geophysical surveys and drilling. In 2020, the brownfield exploration program was directed towards intensifying the diamond drilling work at the Bonsucesso target, confirming zinc and lead mineralization along the strike of the mineralized zone and opening the potential to extend de mineralized bodies. In additional, Nexa performed additional 114 diamond drill holes in Morro Agudo mine with the purpose of Mineral Resources conversion, totaling 18.1 km of drilling.

 

Our expenditures for the Morro Agudo project in 2020 were US$1.4 million, primarily related to exploration and geological activities. In 2020, we drilled 32 exploration drill holes, including Bonsucesso and regional targets, totaling 12.2 km. For 2021, have budgeted a total of US$1.8 million in mineral exploration expenditures and we expect to drill 9.3 km.

 

Morro Agudo does not currently have any estimated Mineral Reserves and is considered an exploration stage property under S-K 1300. Morro Agudo is not considered a material property for the purposes of S-K 1300.

 

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Mining Operations

 

Production

 

The Morro Agudo mine has a treatment plant capacity of 3,400 tonnes of mill feed per day. The table below summarizes the Morro Agudo mine’s concentrate production, metal contained in concentrates produced and average grades for the periods indicated.

 

    For the Year Ended December 31,  
    2020     2019     2018  
Treatment ore (in tonnes)     1,180,621       1,168,396       1,060,932  
Average ore grade                        
Zinc (%)     2.41       2.33       2.70  
Lead (%)     0.49       0.52       0.71  
Metal contained in concentrate production                        
Zinc (in tonnes)     25,177       24,353       26,408  
Lead (in tonnes)     4,019       4,700       6,097  
Silver (in oz)     3,458       22,581       55,704  
Cash cost, net of by-product credits (in US$/t)     1,726.9       2,076.7       1,363.8  
Cash cost, net of by-product credits (in US$/lb)     78.3       0.94       0.62  
Capital Expenditures (in millions of US$)     9.0       15.9       13.3  

 

Concentrate Sales

 

All the metal produced by our mines is contained in concentrates. Our mining operations sell the concentrates that they produce to third parties and to our own smelters pursuant to arm’s length transactions. Each mine bears the cost of transporting the concentrate to the point of sale where the smelter or trader purchases the concentrate. The smelter or trader pays the mine for the percentage of metals contained in the concentrate, net of charges for treating the concentrate and refining the metals. The typical payable percentage is 85% for zinc contained in concentrate minus treatment charges.

 

Growth projects

 

Vazante mine deepening project

 

One of our main brownfield projects is the Vazante Mine Deepening Project, which involves extending the mine life of Vazante mine from 2022 until 2028. The total capital expenditures related to this project in 2020 totaled US$13.0 million and we expect to invest an additional US$2.2 million in 2021. This project began in 2013 and is expected to be completed in 2022.

 

In addition, we are conducting exploration activities below the mine’s current level of operation and alongside the ore body, which we believe will maintain the Vazante mine’s production at 135,000 tonnes of zinc per year until 2031. As part of this project, we are investing in ongoing exploration activities and infrastructure, including expansion of an underground pumping station, an increase in the capacity of the ventilation system, emergency paths, access ramps, electrical networks and substations. During 2020, we assembled and commenced operating the EB347 pumping station.

 

Bonsucesso

 

The Bonsucesso project is a brownfield underground mine project that belongs to the Morro Agudo complex (Ambrosia Trend) and is expected to extend the life of mine of the Morro Agudo complex. The project is located 8 km north of the Ambrosia Sul mine and approximately 60 km north of the Morro Agudo mine. The run-of-mine of Bonsucesso will feed the Morro Agudo processing plant.

 

The project is currently in the feasibility study stage which was placed on hold in 2020 in response to the COVID-19 pandemic. We estimate that we will finalize the study by year-end 2021, when we expect to evaluate the development of the project. Construction will depend on the results of the feasibility study and approval of the project by our board. The total investments related to this project, as of December 31, 2020, totaled US$9.5 million, which includes all project studies (from the scoping study to the feasibility study) and anticipated expenses related to construction and operating infrastructure. The mine will be treated as a satellite mine for the Morro Agudo complex considering that minimum operational facilities are expected at the site and that the Morro Agudo plant will be used for ore processing. Studies are also being carried out to define if the Bonsucesso project will have synergy with the Ambrosia facilities.

 

56

 

 

Mining Operations

 

In 2020, the exploration program was focused on the northern part (infill program) and the central part (extension) of the Bonsucesso deposit, confirming mineral resources and extending the mineralization. Regionally, some drill holes were drilled in the south trend of Ambrosia Mine to investigate the potential mineralized structures.

 

Also in 2020, the project obtained the environmental approval for the installation phase.

 

Our expenditures for this project in 2020 were US$1.4 million, which was primarily related to exploration and geological activities. In 2020, we drilled 32 exploration drill holes, including Bonsucesso and regional targets, totaling 12.2 km. We have budgeted US$1.8 million in mineral exploration in expenditures for 2021 and we expect to drill 9.3 km.

 

Pasco mining complex

 

The Pasco mining complex project involves the integration of the El Porvenir and Atacocha mines. The project is intended to capture synergies between the two mining operations resulting from their proximity and operational similarities, with the goal of obtaining costs and investment savings and reducing our environmental footprint.

 

The integration project is being developed through four stages. The first stage involved the administrative integration of both mines, which was completed in 2014. The second stage involved the integration of the tailing disposal system, which consolidated the operations of the two mines with a single tailing disposal system and thereby helped reduce the environmental footprint. This stage was completed in 2015 and the integrated tailing disposal system commenced operations in the beginning of 2016. The third stage, which was completed in 2016, involved the construction of a new energy transmission line with a 138 kilovolt connection that supplies both mines, replacing the prior 50 kilovolt transmission lines. The development of 3.5 km connecting both underground mines, which is part of the fourth stage, was concluded in 2019.

 

Following the decree published by the Peruvian government that allowed medium-sized mines to restart operations in June 2020, we announced the resumption of operations at the San Gerardo open pit mine, but decided not to restart the higher-cost Atacocha underground mine, which was placed under care and maintenance. Currently, we have not yet determined how long the underground mine’s suspension will last, and the decision will depend on an improvement in the mine’s economic viability. Consequently, in lieu of focusing on the continuation of the integration between El Porvenir and Atacocha’s underground operations and facilities, in 2021 our management is focused on completing modernization and debottleneck studies for the El Porvenir mine in order to deepen the mine and extend its life of mine.

 

Mining greenfield projects

 

Project Name   Current Project Status
Aripuanã   In execution
Magistral   Ongoing feasibility study
Pukaqaqa   Pre-feasibility study on hold
Shalipayco   Pre-feasibility study on hold
Hilarión   Exploration phase
Florida Canyon Zinc   Exploration phase on hold
Caçapava do Sul   On hold

 

We summarize below certain information, including the outlook, for each of our greenfield projects. As of the date of this report, other than the Aripuanã Project none of our other greenfield projects have known Mineral Reserves under S-K 1300.

 

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Mining Operations

 

Aripuanã

 

Location and means of access

 

The Aripuanã project is located in the northwest corner of the Mato Grosso State in western Brazil, approximately 2,529 km by railroad and road to the Três Marias smelter, 2,831 km to the Juiz de Fora smelter or 2,660 km to the port of Santos. The project is accessible from the town of Aripuanã via a 25 km unpaved road, which is well maintained in the dry season. Aripuanã can be accessed from the state capital, Cuiabá, via a 16-hour drive (935 km) on paved and unpaved roads. The final 250 km between Cuiabá and Aripuanã are on unpaved roads in poor condition which require substantial upgrades to ensure road access to the site.

 

The town of Aripuanã is also serviced by a paved airstrip suitable for light aircraft. There are no commercial flights travelling between Cuiabá and the town of Aripuanã, however the site can be accessed via a three-hour chartered flight.

 

History

 

Aripuanã is a world-class underground polymetallic project containing zinc, lead and copper, located in the state of Mato Grosso, Brazil. In 2000, Dardanelos was created to represent a joint venture, or “contract of association,” between Karmin and Anglo American, with the intent of exploring the areas adjacent to the town of Aripuanã for base and precious metals. Anglo American and Karmin held 70% and 28.5% of Dardanelos, respectively, with the remaining interest (1.5%) owned by SGV Merchant Bank (SGV).

 

In 2004, the initial agreement between Karmin and Anglo American was amended to include Nexa Brazil’s participation. Nexa Brazil subsequently acquired 100% of Anglo American’s interest in the project. In 2007, Karmin purchased SGV’s interests, raising its participation to 30%. In 2015, Nexa Peru acquired 7.7% of Nexa Brazil’s interests in Dardanelos.

 

Up until 2019, Dardanelos was a joint venture between subsidiaries of Nexa (70%) and Karmin (30%), with Nexa acting as the operator. In 2019, Nexa purchased Karmin’s interest and became the sole owner of the project. As a result of this acquisition, and following the transfer of the Dardanelos 30% interest in the Aripuanã project from Nexa Peru to Nexa Brazil, Nexa Brazil became the owner of 100% of the Aripuanã project in June 2020.

 

In 2020, we reached an agreement with artisanal miners that are working adjacent to the property belonging to our Aripuanã project, the ANM and the state government whereby Nexa assigned these artisanal miners an area to exercise their activities subject to certain conditions. The increase of artisanal mining activity or the failure of these artisanal miners to abide with our agreement may have an adverse effect on the development of our operations in Aripuanã.

 

Titles, leases and options

 

The project consists of a contiguous block comprised of one mining concession (3,639.9 hectares), which is the core tenement, two mining concession applications (1,387.2 hectares), one right to apply for mining concession (1,000.0 hectares), thirteen exploration licenses (52,104.8 hectares) and three exploration applications (8,196.2 hectares), totaling 66,328.1 hectares.

 

Mineralization

 

The Aripuanã region contains polymetallic VMS deposits with zinc, lead and copper, as well as small amounts of gold and silver, present in the form of massive mantles and veins, located in volcano sedimentary sequences belonging to the Roosevelt Group of Proterozoic age.

 

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Mining Operations

 

Four main elongated mineralized zones have been defined in the central portion of the project: (1) Arex, (2) Link, (3) Ambrex and (4) Babaçu. Limited exploration has identified possible additional mineralized bodies including Massaranduba, Boroca and Mocotó to the south and Arpa to the north.

 

The Aripuanã polymetallic deposits are typical VMS deposits associated with felsic bimodal volcanism. The individual mineralized bodies have complex shapes due to intense tectonic activity. Stratabound mineralized bodies tend to follow the local folds, however, local-scale, tight isoclinal folds are frequently observed, usually with axes parallel to major reverse faults, causing rapid variations in the dips.

 

Massive, stratabound sulphide mineralization as well as vein and stockwork-type discordant mineralization have been described on the property. The stratabound bodies, consisting of disseminated to massive pyrite and pyrrhotite, with well-developed sphalerite and galena mineralization, are commonly associated with the contact between the middle volcanic and the upper sedimentary units. Discordant stringer bodies of pyrrhotite-pyrite-chalcopyrite mineralization are generally located in the underlying volcanic units or intersect the massive sulphide lenses and have been interpreted as representing feeder zones.

 

In 2020, the drilling campaign at Aripuanã focused on exploring the Babaçu mineralized zones and confirmed the presence of mineralization along 1.3 km of the strike. We spent US$1.4 million on Aripuanã exploration, maintenance, and geological activities. In 2020, we drilled seven drill holes, including Aripuanã brownfield and regional targets, totaling 4.2 km. For 2021, we expect to invest an additional US$2.2 million in a brownfield exploration program, drilling 11.4 km.

 

Project implementation

 

On October 6, 2020, we published an update on the Aripuanã project. The total estimated CAPEX has increased to US$547 million, compared to the US$392 million set out in the Aripuanã feasibility study published in 2018, based on a detailed review and update of the project. The project timeline was also affected and mechanical completion is expected in 4Q21. Production is scheduled to start in early 2022 with an estimated zinc equivalent production of 108kt for the year.

 

Cost increases and time extension resulted primarily from, among other factors:

 

§ The delays and outcome of detailed engineering studies resulting in increases in certain quantities including earthworks and construction materials, investment in mine development, consumables and spare parts, among others;
§ Additional infrastructure services due to issues experienced during earthworks activities;
§ Additional scope such as new equipment and infrastructure items in the process plant and in the tailings dry-stacking piles and at the Dardanelos power station;
§ Increase in third-party services;
§ Upgrades at the Dardanelos energy substation;
§ Logistics constraints on the upgrade of the Aripuanã river bridge; and
§ The global impact of COVID-19.

 

In mid-2020, we reorganized the project team and changed the scope of key contractors to address these issues and mitigate further potential risks.

 

By year-end 2020, approximately 136 thousand tons of treated ore was stockpiled. We also continued to make progress on related project infrastructure. This included placing lean concrete in the grinding area, constructing pipe rack foundations and assembling steel structures, laydown pipes and equipment, temporary buildings and laydown areas and constructing roads providing access to the site, as well as a water dam, beneficiation plant and waste ore stockpile. During 2020, we completed 100% of earthworks for the mine’s waste dump (Pile 2) (drainage and waterproofing).

 

In addition, we received initial components for the mills and vibrating screen at the temporary buildings and laydown areas. We closed all the critical packages, except for the assembly and civil works at the Energética Águas da Pedra S.A. (“EAPSA”) substation’s adequation package awarding, which will be concluded by the first quarter of 2021. Archeological activities for the transmission line foundation towers at the site were completed, which will not impact any works to be performed by Energisa. The embankment for the water dam and spillway was concluded, and the construction of the wetlands is in progress.

 

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As of December 2020, there were over 3,000 people working in the main construction areas. We also implemented a qualification program for future mine and operation plant professionals which had 248 candidates enrolled in 2020, approximately 104 of whom received professional qualifications on maintenance and automation and geology and surveying. Of the total number of participants, 52% were women.

 

In 2020, we invested US$187 million in capital expenditures on the project with cumulative incurred capital expenditures of US$312 million since the beginning of the construction. In 2021, we estimate that we will invest US$232 million in Aripuanã, which represents 42% of the US$547 million in total estimated capital expenditures for the project with the remainder of US$1 million expected to be spent in 2022.

 

The Aripuanã project is scheduled to start its operations in early 2022. As of the date of this report, construction activities at the project are ongoing and on time. Additional safety measures and procedures have been implemented with our contractors to mitigate any potential further impact of the global COVID-19 pandemic such as testing for all manpower returning from year-end holidays.

 

Mineral Reserves and Mineral Resources

 

Aripuanã – Year End Mineral Reserves as of December 31, 2020

 

Ownership (%)(2)     Class     Tonnage     Grade     Contained Metal  
                  Zinc     Copper     Silver     Lead     Gold     Zinc     Copper     Silver     Lead     Gold  
            (Mt)     (%)     (%)     (g/t)     (%)     (g/t)     (kt)     (kt)     (koz)     (kt)     (koz)  
      Proven       10.08       3.74       0.31       36.0       1.39       0.29       376.7       31.3       11,676       140.1       94.5  
  100.0 %     Probable       13.42       3.60       0.21       32.9       1.33       0.33       483.1       28.4       14,211       178.9       141.5  
          Subtotal       23.51       3.66       0.25       34.3       1.36       0.31       859.8       59.7       25,887       319.0       236.1  

Notes:

1. Subpart 1300 of Regulation S-K definitions were followed for Mineral Reserves, which also are consistent with the CIM (2014) definitions.
2. Mineral Reserves data presented in this table represents 100% of the mineral reserves estimates for the property.
3. Numbers may not add due to rounding.
4. The qualified person for Mineral Reserves is SLR Consulting, an independent mining consulting firm.
5. Mineral Reserves have an effective date as of September 30, 2020.

 

The Aripuanã Mineral Reserves estimates, which are as of September 30, 2020, are based on modifying factors from the Aripuanã Project and based on three main orebodies: Arex, Link and Ambrex. The main commodities produced are zinc, lead, copper, silver and gold. The dilution that has been applied is related to the selected mining method. The two main mining methods used at Aripuanã are longitudinal longhole retreat (“bench stoping”) and transverse longhole mining (vertical retreat mining, or “VRM”) with primary and secondary stope extraction. Dilution is applied on a percentage basis, with no grade applied to the diluting material. The NSR cut-off value was determined using the mineral reserve metal prices, metal recoveries, transport, treatment, and refining costs, as well as mine operating cost. The break-even NSR cut-off value is approximately US$34.35/t. A minimum mining width of 4.0 m was used. First-pass mine design used a cut-off value of US$45/t, to allow for uncertainty around exchange rates (break-even cut-off NSR plus a US$10/t margin). Upon review of the results, a limited number of stopes with NSR values down to US$40.00/t were included for continuity. Metal prices are estimated using multiple variables including supply (mine and refined), demand, cost drivers, capital cost and other key elements. The long-term prices derived are in line with the consensus forecasts from banks and independent institutions. The Mineral Reserves are estimated using an average long term zinc price of US$2,494.90/t (US$1.13/lb), lead price of US$1,956.00/t (US$0.89/lb), copper price of US$6,457.90/t (US$2.93/lb), silver price of US$16.85/oz and gold price of US$ 1,538/oz, and metallurgical recoveries are based on metallurgical testworks. The two main types of mineralization in the deposit are stratabound and stringer. These two types of mineralization have different processing characteristics, and as a result, different parameters are used to calculate their respective NSR value.

 

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For more information, see Section 12 of our Technical Report Summary for Aripuanã filed as Exhibit 15.4 of this annual report on Form 20-F.

 

Aripuanã – Net difference in Mineral Reserves between December 31, 2020 versus December 31, 2019

 

Ownership (%)(1)     Class     Tonnage     Contained Metal  
                  Zinc     Copper     Silver     Lead     Gold  
            (Mt)     (kt)     (kt)     (koz)     (kt)     (koz)  
      Proven       -1.72       -71.7       -4.1       -1,716       -25.1       -19.3  
  100 %     Probable       -0.96       -48.9       -0.4       -1,277       -8.1       +2.8  
          Subtotal       -2.67       -120.6       -4.4       -2,993       -33.1       -16.5  

 

(1) The information presented in this table includes 100% of the mineral reserves estimates for the property.

 

Overall, as of December 31, 2020 the Mineral Reserves of Aripuanã have decreased mainly due to review in mining costs, changes in NSR calculations and cut-off values, changes in model due to reinterpretation, changes in geotechnical constraints and mine design review. For more information, see Sections 11 and 12 of our Technical Report Summary for Aripuanã filed as Exhibit 15.4 of this annual report on Form 20-F.

 

Aripuanã – Year End Mineral Resources as of December 31, 2020

 

Ownership (%)(2)     Class     Tonnage     Grade     Contained Metal  
                  Zinc     Copper     Silver     Lead     Gold     Zinc     Copper     Silver     Lead     Gold  
            (Mt)     (%)     (%)     (g/t)     (%)     (g/t)     (kt)     (kt)     (koz)     (kt)     (koz)  
      Measured       2.92       2.50       0.38       29.8       0.93       0.29       72.9       11.1       2,795       27.3       27.4  
  100.0 %     Indicated       5.17       1.86       0.27       18.2       0.63       0.43       96.3       13.9       3,021       32.4       71.0  
          Subtotal       8.09       2.09       0.31       22.4       0.74       0.38       169.2       25.1       5,816       59.7       98.4  
          Inferred       39.45       3.31       0.33       33.8       1.22       0.58       1,306.6       131.3       42,906       482.1       736.5  

Notes:

1. Subpart 1300 of Regulation S-K definitions were followed for mineral resources, which also are consistent with the CIM (2014) definitions.
2. Mineral Resources data presented in this table represents 100% of the mineral resources estimates for the property.
3. Mineral Resources are reported exclusive of those mineral resources that were converted to mineral reserves, and mineral resources are not mineral reserves and do not have demonstrated economic viability.
4. Numbers may not add due to rounding.
5. The qualified person for mineral reserves is SLR Consulting, an independent mining consulting firm.
6. Mineral Resources have an effective date as of September 30, 2020.

 

The Mineral Resources estimates for the Aripuanã Project were completed for Babaçu, Arex, Ambrex and Link. The block models were created using Datamine and Leapfrog software. Wireframes for geology and mineralization were constructed in Leapfrog based on geology sections, assay results, lithological information and structural data. Assays were capped to various levels based on exploratory data analysis and then composited to one meter lengths. Wireframes were filled with blocks measuring 5 meters by 5 meters by 5 meters for Arex, Link, and Ambrex, and 10 meters by 5 meters by 5 meters for Babaçú with sub-celling at wireframe boundaries. Blocks were interpolated with grade using OK and ID3. Blocks estimates were validated using industry standard validation techniques. Classification of blocks was based on distance-based criteria. Potentially mineable shapes of underground mineral resources are generated using DSO software, envisaging bulk longhole stoping and the C&F mining method. The Mineral Resources of the Aripuanã project are reported using a US$45/t cut-off value for VRM and bench stoping areas and US$55/t cut-off value for C&F areas. Mineral resources are estimated using average long-term metal prices of zinc: US$2,869/t (US$1.30/lb); lead: US$ 2,249/t (US$1.02/lb); copper: US$7,427/t (US$3.37/lb); gold: US$1,768/oz and silver: US$19.38/oz, and metallurgical recoveries are based on recovery curves derived from historical processing data.

 

For more information, see Section 11 of our Technical Report Summary for Aripuanã filed as Exhibit 15.4 of this annual report on Form 20-F.

 

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Magistral

 

The Magistral mining project is located in the Ancash region of Peru, approximately 450 km northeast of the capital of Lima and approximately 140 km east of the port city of Trujillo. The Magistral property can be reached by vehicle by driving a total of 272 km from Trujillo, much of which consists of poorly maintained roads that traverse steep topography. The Magistral Project consists of a large, irregularly shaped block of contiguous concessions and two smaller, non-contiguous single concessions. The Magistral Project comprises 36 granted concessions, totaling 16,282.49 hectares. The project intended to be an open pit copper mine with molybdenum concentrate as a byproduct. In 2016, ProInversión approved an initial feasibility study, which set forth production rates starting at 10 thousand tonnes per day and achieving 30 thousand tonnes per day. In 2016, the Ministerio de Energía y Minas (“MINEM”) approved an environmental impact assessment (“EIA”), to process up to 30 ktpd. An EIA modification is currently in progress to adjust the location of some facilities.

 

Nexa Peru was awarded the contract to develop the Magistral mining project in 2011, which has been amended from time to time. Nexa made an initial payment of US$8.0 million to acquire the Magistral concessions, subject to a 2.0% NSR royalty upon production. Under the terms of the contract in 2016, Nexa Peru exercised the option by committing to invest a minimum 70% of declared initial capital expenditures by September 2024 and has previously extended this period. Pursuant to the terms of this commitment, Nexa Peru would be required to pay a penalty in the event it fails to invest the specified amounts during this period. The Magistral project has a total of 36 concessions covering approximately 16,282.5 hectares. Nexa Peru currently holds a 100.0% interest in 13 of the 36 concessions, Nexa holds 21 concessions by way of a lease agreement entered into with Companía Magistral S.A.C. and Companía Minera Atacocha S.A.A., a company also controlled by Nexa Peru, holds a 100.0% interest in two concessions. We spent approximately US$8.4 million on the project in 2020. The Magistral project is in the feasibility study phase and engineering studies continue to progress.

 

In 2021, we expect to advance further detailed engineering and optimization opportunities to mitigate the risk of project execution, before consideration of the project’s approval.

 

Mineralization Developments

 

The Magistral property is near the northeastern end of the Cordillera Blanca, a region that is underlain predominantly by Cretaceous carbonate and clastic sequences. These units strike north to northwest and are folded into a series of anticlines and synclines with northwest-trending axes.

 

The Cretaceous sedimentary rocks are bounded to the east by an early Paleozoic metamorphic terrane composed mainly of micaceous schist, gneissic granitoid and slate. The Cretaceous sedimentary sequence unconformably overlies these metamorphic rocks. The Cretaceous rocks are structurally overlain by black shale and sandstone of the Upper Jurassic Chicama Formation that were thrust eastwards along a prominent regional structure. The Chicama Formation was intruded by granodiorite and quartz diorite related to the extensive Cordillera Blanca batholith, which has been dated at 8.2 +/- 0.2 Ma. Several major structural features are evident in the Cretaceous sedimentary rocks in the Magistral region, including anticlines, synclines, and thrust faults. The trend of the fold axes and the strike of the faults changes from northwest to north near Magistral.

 

Through the end of 2015, a total of approximately 101,900 m of surface diamond drilling has been completed in 486 drill holes. In addition, 14 short underground diamond holes were drilled for a total of 1,298.8 m in the San Ernesto, Arizona, and Sara zones between 1969 and 1973. In 1999, 2000, and 2001, Anaconda drilled 76 diamond drill holes totaling 24,640 m. All surface drilling from 2000 onward was carried out on northeast (035o) and northwest (305o) oriented sections. In 2004, Ancash Cobre (or Inca Pacific) completed 34 drill holes, totaling 7,985 m, and in 2005 Ancash Cobre (or Quadra) drilled 14,349 m in 60 holes. Milpo’s drilling in 2012 was contracted to Redrilsa Drilling S.A. (or Redrilsa). Since 2012, the drilling has been contracted to Geotecnia Peruana S.R. Ltda. (or Geotecnia Peruana).

 

Of the 71 holes drilled in 2013, six were drilled to gain geotechnical information and the remainder were infill holes. Drilling in 2014 consisted of a combination of infill, geotechnical, and metallurgical holes. The 2015 drilling consisted entirely of infill holes. No drilling program was carried out on the project during 2020.

 

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Exploration Developments

 

Since acquiring the Magistral project in 2011, Nexa has initiated a comprehensive exploration program consisting of geological mapping, prospecting and sampling, ground geophysical surveying, and diamond drilling. Geological mapping at a scale of 1:2,000 was completed in the Ancapata area and the area north-northeast of Magistral over an area of 386.50 hectares. The objective was to verify and supplement the information available from Ancash Cobre’s exploration.

 

From October 2012 to January 2014, Arce Geofisico SAC was contracted to complete ground magnetic and Induced Polarization (IP) surveying over an area of 520 hectares covering the Magistral deposit and the adjoining Ancapata area. The objective was to characterize the geophysical signature of the Magistral deposit and to survey the Ancapata area. Work was completed on 100 m spaced lines oriented at N125°W. An initial 30 line-km survey was expanded to 55.1 line-km of IP and 57.25 line-km of ground magnetics in order to delineate chargeability and resistivity anomalies. Drilling ceased on the property in 2015. No exploration work was carried out on the project during 2020.

 

Pukaqaqa

 

The Pukaqaqa project contemplates the development of an open pit copper and molybdenum mine, with gold credits, and is located in the Huancavelica region of Peru. The mineralization is hosted by an epithermal breccia system that is associated with exoskarn and endoskarn alterations. Given the geological setting, we believe that a porphyry copper system remains undiscovered below the currently explored mineralization, which will be explored in the following phases. The Pukaqaqa project has a total of 34 concessions covering approximately 11,131.3 hectares.

 

In 2015, the MINEM approved Pukaqaqa’s EIA, which allowed a treatment capacity of up to 30 ktpd. In 2017, a scoping study was developed by JRI, a Chilean engineering firm, enabling the start of a drilling campaign in 2018 to obtain samples for metallurgical testing.

 

The pre-feasibility study progressed until the end of FEL2-A phase (equivalent to the trade-offs phase). Metallurgical results indicated the need to further explore copper and molybdenum recoveries prior to progressing with the pre-feasibility study. During 2019 and 2020 a new laboratory campaign was initiated in Chile, which was temporarily suspended due to COVID-19 restrictions. The first part was concluded in December 2020, demonstrating better results than previous campaigns, including improved recoveries and grades. During 2021, variability tests to confirm results will be held.

 

In 2020, we spent approximately US$1.5 million on this project, related to metallurgical tests. In 2021, we have budgeted US$2.4 million for the Pukaqaqa project, which allows for further metallurgical testing and environmental closure works in the drilling area.

 

Shalipayco

 

The Shalipayco project, located in the Central Andes of Peru, is a joint venture between Nexa Peru (which holds a 75.0% interest) and Pan American Silver Perú S.A.C. (which holds a 25.0% interest). It is a potential underground polymetallic project containing zinc, lead and silver deposits. This project consists of mining concessions with evidence of MVT mineralization, which is a deposit type similar to our Morro Agudo mine. The Shalipayco mineralization is mainly located within the Chambará formation that is part of the Pucará Group, considered the most important Peruvian location for MVT mineralization. The Shalipayco project has a total of 52 concessions covering approximately 22,609.0 hectares and one mineral claim totaling 740.6 hectares.

 

In 2020, we spent approximately US$0.9 million on this project relating to maintaining the office and warehouse facilities in Carhuamayo, and to conducting some desktop analysis in relation to the pre-feasibility study. All field activities in Shalipayco were on hold during 2020 due to the COVID-19 pandemic and, as a result of government ordered lockdowns, no exploration activities were carried out in 2020. There is no budget for exploration in 2021. Although metallurgical tests are ongoing, the pre-feasibility study remains on hold as negotiations to obtain our social license with the local community of Carhuamayo are ongoing.

 

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Hilarión

 

The Hilarión project is located in the Department of Ancash, approximately 230 km north of Lima, the capital of Peru, and approximately 80 km south of the city of Huaraz and is accessible by paved road from Lima. It consists of 71 mineral concessions covering an area of approximately 15,408.3 hectares and one mineral claim totaling 209.7 hectares. Hilarión is a skarn mineral deposit made of vertical tabular ore bodies containing sulfide zinc, lead, silver and copper deposits. Hilarión and El Padrino and other occurrences in proximity to them (Mia, Eureka and others) constitute a large mineralized system, open in several directions for a potential increase in resources, extended mine life and increased production capacity in the future. The conceptual plan for the project includes the development of an underground mine that could either use its own processing plant or use one of the several existing plants in the area, such as Pachapaqui, Huanzala and Atalaya plants.

 

From 2005 to 2014, in addition to mapping, remote sensing, topographical and geophysical surveys, we completed four drilling campaigns totaling 244.0km on Hilarión and El Padrino deposits. During 2018-2019, two additional drilling campaigns totaling 17.1km were carried out. The recent 2018-2019 drilling predominantly focused on the Hilarión North zone. During 2019, we drilled 12 drill holes totaling 9.1 km at Hilarión. High grade and thick intercepts revealed continuity of the mineralized zones of the deposit to the north and south and demonstrated the potential for resource increase.

 

In 2020, we executed 4.6 km of diamond drilling testing in the extension of the Hilarión mineralization trend to the northeast towards the Mia and Hilarión South targets, totaling 5 drill holes, and completed the sampling for metallurgical test studies.

 

In 2020, we spent approximately US$5.0 million on the Hilarión project, including project maintenance and exploration activities such as geological mapping, rock chipping, diamond drilling and permitting.

 

On March 5, 2020, we filed a preliminary economic assessment (“PEA”) for the Hilarión project, prepared jointly by Nexa and Roscoe Postle Associates Inc (“RPA”), disclosing an updated mineral resource, plant production and economics estimate in accordance with NI 43-101 (as of December 31, 2019 with a drilling cut-off date of December 5, 2014).

 

In 2021, we have budgeted US$7.9 million for the Hilarión project and planned 14.1 km of diamond drilling to test the southern projection of the Hilarión mineralized trend at the south of Hilarión deposit, where Zn, Pb, Cu, Ag mineralized veins trending east-west and north-south occur at surface level, as well as a sampling campaign of 10 tons for ore sorting tests.

 

Florida Canyon Zinc

 

The Florida Canyon Zinc project, comprised of 16 contiguous mining concessions, covering approximately 12,600.0 hectares, is owned and operated by Minera Bongará S.A., a joint venture between Nexa Peru, Solitario Exploration and Royalty Corp. and Minera Solitario Peru S.A.C. (collectively, Solitario) in existence since 2006. As of December 31, 2020, Nexa Peru owns a 61.0% interest in this joint venture, which may increase up to 70.0% upon Nexa Peru’s satisfaction of certain conditions. Although a pre-feasibility study relating to the Florida Canyon Zinc was released in 2017, the project continues to be treated as an advanced mineral exploration project.

 

During 2019, we started work to improve the access road, which we expect to reduce logistical costs. We also drilled in the Florida Canyon region, focusing on two sulfide concentration areas, which are related to feeders that generate the concentration of sulphides in the mantos, bodies and veins mineralization.

 

In 2020, we continued to work on the access road repair to reduce logistical costs. Another important activity carried out in 2020 was the update of the geological model based on the 2018-2019 drilling campaign and by improving ore-type definition (oxide-mixed-sulfide) by using qualitative and quantitative analytic data, that helped in ore classification for the 2020 mineral resource estimation.

 

In 2020, we spent approximately US$1.4 million on this project. In 2021, we have budgeted another US$1.4 million for the Florida Canyon Zinc project, including US$0.4 million for Heli-borne Magnetic survey to cover 49,300 hectares, US$0.45 million for access road maintenance and construction and US$0.4 million to obtain a new environmental permit for drilling plans beyond 2022. The remaining budget is for maintenance of the project structure and social programs for the local community.

 

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Caçapava do Sul

 

The Caçapava do Sul project is a joint venture between Mineração Santa Maria Ltda., a wholly owned subsidiary of Nexa Brazil, which holds a 56.00% interest, and IAMGOLD Corporation, which holds a 44.00% interest. Nexa Brazil is the operator of the joint venture. The Caçapava do Sul project is a polymetallic project that has the potential to be mined by open pit and underground methods.

 

In 2020, Nexa reviewed the drilling data information to identify upsides on the brownfield area, but no drilling was executed. In 2020, we spent approximately US$0.4 million on the Caçapava do Sul exploration project for maintenance of project structures. For 2021, we have not budgeted any money for exploration activities. The Caçapava do Sul project is on hold as a result of our current capital allocation strategy.

 

Other Greenfield Exploration Projects

 

Project in Namibia

 

We have been developing exploratory work in Namibia since 2015, as part of a joint venture with the Japan, Oil, Gas and Metals National Corporation (“JOGMEC”), a Japanese state-owned company. The project was part of a farm-out process of the Namibian tenements inherited from the former strategy of Votorantim Metals to explore opportunities in Africa, where Nexa has a back-in right to invest and maintain participation depending on exploration results. The exploration area is located 360 km north of Windhoek. This early-stage exploratory program is targeting sediment-hosted copper mineralization, such as the Tsumeb and Kombat mines, both of which contain rocks from the Otavi Mountain land terrain.

 

Nexa currently holds 374,000 hectares in 16 exclusive prospective licenses (“EPL”). As of 2019, a total of 22.1 km was drilled. The 2020 exploration expenditures totaled US$3.4 million ($2.6 million for JOGMEC expenditures and US$0.8 million for Nexa expenditures) with a total of 10,751 meters drilled. In 2021, we have budgeted US$2.8 million for this exploration program (US$2.0 million for JOGMEC and US$0.8 million for Nexa). Nexa is currently focusing on scout exploratory drilling to evaluate the mineral potential of previously-defined targets in Namibia.

 

Permits & authorizations for greenfield projects

 

The following table summarizes the status of the main permits and authorizations for our greenfield projects.

 

Project   Status
Aripuanã   On December 20, 2018, SEMA/MT granted the installation license for the Aripuanã project, which allowed us to begin construction.
The mineral exploration operation license (“LOPM”) is valid until May 2022 which allows drilling activities in the project.
On November 27, 2020, the request for the Transmission Line 69kV Operation Permit was filed. The project is under development.
Magistral   The EIA was renewed in 2019 and is valid for an additional two years, until September 2021. An amendment to the EIA is currently being processed.
Pukaqaqa   In 2020, a new environmental impact statement (“EIS”) was approved, with the purpose of developing exploration activities in Pukaqaqa Sur Exploration Project.
Shalipayco   The EIA for exploration activities approved in 2017 was modified in early 2019 and extended to 2023.

Hilarión   The most recent environmental study is the fifth modification to the Hilarion Project’s EIS, which consisted of obtaining approval for new exploration platforms and reviewing the drilling program. It was approved in 2020 and is valid until 2024.
The El Padrino deposit has an authorization for exploration activities until 2022 and a detailed EIS was approved in 2020.
For the Azulmina target, one possible location for the plant and tailings facilities, there is an approved EIS that allows the execution of exploration activities until 2021.
Florida Canyon Zinc   During 2018, we obtained a new exploration permit to resume exploration activities, which is valid until 2022.
Caçapava do Sul   The drilling environmental licensing process was cancelled in 2020 due to the stoppage of mineral exploration activities. An EIA was submitted in 2016 to the Fundação Estadual de Proteção Ambiental Henrique Luiz Roessler. A new term of reference was issued in 2020, with a two-year deadline for submitting new environmental studies.

 

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Tailings disposal

 

Regulatory framework

 

We are subject to several environmental regulations related to the use of tailings dams and effluent dams.

 

In Brazil, recent tailings dams’ failures have triggered the issuance of new regulations. On January 25, 2019, there was a tragic failure of a tailings dam in the city of Brumadinho, in the state of Minas Gerais, Brazil. The Brumadinho dam was built using the upstream method and belongs to Vale S.A. A report by a panel of technical experts commissioned by Vale S.A. found that the tailings dam failure was the result of flow liquefaction within the tailings in the dam. Another upstream-method tailings dam in Brazil, the Fundão tailings dam owned by Samarco Mineração S.A., failed in November 2015. Each of these failures released muddy tailings downstream, flooded certain communities, caused fatalities and resulted in extensive environmental damage to the surrounding area.

 

In response to these tragedies, the state of Minas Gerais enacted regulations in February 2019 affecting the use of dams in the state, including tailings dams and effluent dams that mandate the decommissioning of all upstream tailings dams and prohibit construction of new tailings dams using the upstream method. Additionally, a rule approved by the ANM requires all inactive upstream dams to be decommissioned by 2021 and active upstream dams to be decommissioned by 2023. We have not been impacted by these regulations as all of our tailings dams in Brazil are downstream.

 

In addition, in February 2019, the state of Minas Gerais enacted regulations that prohibit the construction of a new dam or the expansion of existing dams if communities are established within its self-rescue zone, an area encompassing the portion of the valley downstream of the dam where timely evacuation and intervention by the competent authorities in emergency situations is not possible. We have two dams at our smelters located in Minas Gerais. In 2019, we concluded construction on the Juiz de Fora dam project and started construction of the Três Marias dam in 2020, which we expect to begin operating in 2021. We believe that these projects will not be impacted by these regulations, as both projects received their installation licensing before the recent regulatory changes. However, future licensing for new tailings storage facilities could take longer than expected to obtain or not be viable at all.

 

In 2020, the mining authorities in Brazil enacted two regulations that establish new procedures related to dams. The first resolution (Resolução ANM 32/2020), decreed in May 2020, determines procedures to develop dam break studies and deadlines to update the Emergency Action Plan (“EAP”) depending on the dam class. This regulation updated previous mining agency standards. We have updated the dam break studies of all mining dams according to these procedures. The second resolution (Resolução ANM 51/2020), decreed in December 2020, defines procedures to certify the EAP. At the end of 2020, the Brazilian Federal Authorities decreed that the new dam safety law (law 14,006/2020) updates the previous dam safety law enacted in 2010. This new law defines that EAP is mandatory to all mining dams.

 

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Mining Operations

 

In Peru, the upstream method has long been an abandoned practice due to seismic concerns in the region. As of 1995, compulsory guidelines were passed prohibiting the use of such method. Subsequently, in 2014 environmental regulators, and later technical regulators, in 2015, adopted the same guidelines prohibiting construction and operation under the upstream method, allowing only the use and construction under the centerline and downstream methods. A specialized governmental agency carries out annual inspections of tailings dam and mining infrastructure, ensuring technical and environmental regulations are complied with. In addition, mining operations must submit biannual stability studies, to which they are held liable.

 

For more information, see “Risk factors—Operational risks—The failure of a tailings dam could negatively impact our business, reputation and results of operations, and the implementation of associated regulations and decommissioning processes may be expensive.”

 

Nexa’s practices

 

We monitor tailings and waste dams according to international best practice guidelines for management and project design based on criteria set by the International Commission on Large Dams (“ICOLD”) and the Canadian Dam Association (“CDA”) dam safety guidelines. In 2020, all of our tailings dams in Brazil received Stability Condition Declarations (“DCEs”), certifying that these facilities are safe and stable. These certifications are carried out every semester in Brazil and once per year in Peru. As of the date of this annual report, all tailings dams in Peru are undergoing the certification process, which will be concluded in the first half of 2021. In addition, all our dams and dry stacking structures are monitored under a system known as the Sistema de Gestão de Barragens ou Depósitos / Tailing Dam Management System (“SIGBAR/SIGDEP”), which consists of procedures, tools and key performance indicators, monthly reports and monitoring and analysis by an independent Geotechnical Engineer. The monitoring procedures include regular inspections, as well as internal and external audits.

 

In addition to the above-mentioned policies and procedures, in 2019 we established a sustainability committee of our board of directors to oversee sustainability related issues, including the management and governance of our tailings disposals. In 2020, the mandate of the sustainability committee was updated to include capital projects oversight and the committee became the sustainability and capital projects committee. The committee assists and advises our board in supporting safe and sustainable business practices in our conduct and activities, as well as in reviewing technical, economic and social matters with respect to our projects. In 2020, management reviewed the Emergency Action Plan (“EAP”) for all mining dams in accordance with the new Brazilian regulations released midway through 2020. In 2020, we trained our internal team in these new procedures.

 

We use four disposal options for tailings. Our preferred option is to convert part or all of the tailings material into a commercially viable product. We use this method at our Morro Agudo mine, where most of the tailings that we produce are ZinCal, a limestone rich in zinc that is used as fertilizer. This option does not require disposal of tailings materials.

 

When the conversion method is not available, we prefer to use the backfill method for our underground mines. This technique involves removing moisture from tailings, creating a mixture with cement and filling open spaces in the mines with this combination. We believe this method reduces safety risks related to tailings disposal given that it provides greater geotechnical stability and does not involve the building of a dam or dry stacking structure.

 

If neither the conversion nor the backfill method is available, we prefer to use the dry stacking method, which involves removing moisture from tailings and stacking them in layers to form an artificial mountain covered with soil and vegetation, causing it to integrate into the local landscape. We use the dry stacking and backfill methods at our Cerro Lindo mine in Peru since the startup of our mine. In 2019, we started operating a dry stacking facility, which substituted the tailings dam in Vazante. With this new structure, over 80% of our tailings disposal is done either through backfill or dry stacking, reducing our exposure to dams. We are currently developing the backfill and dry stacking methods at our Aripuanã greenfield project.

 

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Mining Operations

 

When neither of these three methods is possible, we use tailings dams, which are open spaces built between two walls, which forms a reservoir where the tailings are stored. The dam acts as a solid barrier engineered to prevent the tailings material from escaping to the environment around the mine. We use this method in Peru at our El Porvenir and Atacocha mines and at our Cajamarquilla smelter, and in Brazil at our Vazante and Morro Agudo mines and Juiz de Fora and Três Marias smelters. We also use a combination of the backfill method and tailings dams at our El Porvenir and Atacocha mines in Peru. At the Aripuanã project, we are building a water dam to supply water to our plant. This dam is engineered with borrowed material and uses the technical control of compaction of the soil.

 

We raise our tailings dams using the following two methods: (i) the downstream method, where the building material is disposed downstream of the crest of the dam body; and (ii) the center-line method, where the building material is disposed partially downstream and partially upstream of the crest of the dam body, while maintaining the same center-line of the crest. Historically, we have also used the upstream method – where the building material is disposed upstream of the crest of the dam body – in certain instances.

 

In addition, we also use effluent dams, which are dams used to treat water that contains tailings particles or other solid particles. The effluent dams separate the tailings particles or other solid particles from the water by retaining the particles and releasing the clean water downstream. Finally, we use products dams for the provisional storage of ZinCal prior to its sale.

 

We currently have 47 disposal facilities (including tailings dams, dry stacking facilities, effluent dams and products dams), 22 of which are operational. Of our eight operational tailings dams, seven were raised using either the downstream method or the center-line method, and one dam was at one point raised using the upstream method but was later raised using the downstream and the center-line methods. Of our 25 non-operational tailings dams, 16 are in the process of being decommissioned, and we have plans to decommission the others. Three of our non-operational dams in Peru were originally raised using the upstream method.

 

The following is an overview of the dams we have in place at our principal mining and smelting facilities:

 

Peru

 

· At Cerro Lindo, we have no tailings dams, and tailings are disposed of using a combination of the backfill method, two dry stacking structures and two effluent dams.

 

· At El Porvenir and Atacocha, tailings are disposed of using a combination of the backfill method and tailings dams; there are two tailings dams in active use and four non-operational tailings dams, which are in the process of being decommissioned.

 

· At Cajamarquilla, there are three tailings dams in active use and four non-operational tailings dams, which are in the process of being decommissioned.

 

· At the Chapi mine property, which is currently inactive, there are five non-operational tailings dams.

 

· At the Sinaycocha property, which is part of our Atacocha mine property, there are two non-operational tailings dams.

 

Brazil

 

· At Morro Agudo, most tailings are converted for sale, and the product is stored temporarily at two products dams until it is sold. A separate tailings dam is used to store tailings that are not convertible into product.

 

· At our Ambrósia mine, there is one effluent dam in active use.

 

· At Vazante, tailings are disposed of using a combination of tailings dams and dry stacking; there is one tailings dam and one effluent dam in active use.

 

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Mining Operations

 

· At Juiz de Fora, there is one tailings dam in active use, three effluent dams in active use and six non-operational tailings dams, five of which are in the process of being decommissioned.

 

· At Três Marias, there are three tailings dams in active use and three non-operational tailings dams, which are in the process of being decommissioned.

 

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Smelting Operations

 

Smelting operations

 

The table below provides an overview of our smelting facilities:

 

Smelting Unit   Location   Smelting
Process
  Principal
Refined Zinc
Products
  Plant
Capacity
    Metallic Zinc
Production
in 2020
    Zinc Oxide
Production
in
2020
    Other
Products
                (in tonnes of
refined zinc
per year)
    (in tonnes of
zinc metal
available for
sale, includes
alloys)
    (in tonnes of
zinc oxide)
     
Cajamarquilla   Peru   RLE   Metallic zinc (SHG, CGG jumbos and alloys)   344,436       305,389       0     Sulfuric acid, silver concentrate, copper cement and cadmium sticks
Três Marias   Brazil   RLE   Metallic zinc (SHG, CGG jumbos, alloys and Zamac) and zinc oxide   192,199       202,764 ¹     35,258     Cadmium briquettes
Juiz de Fora   Brazil   Waelz Furnace and RLE   Metallic zinc (SHG, alloys and Zamac)   96,923       79,410 ²     0     Sulfuric acid, sulfur dioxide, silver concentrate, copper sulfate and zinc ash
Total               633,558       587,562       35,258      

 

 

(1) Including 22,353 tonnes of zinc ashes and drosses, as well as metallic zinc used in the production of zinc oxide, zinc granules and zinc powder. Does not include zinc cathode to Juiz de Fora.
(2) Including 2,772 tonnes of zinc ashes and drosses and 489 tonnes of zinc cathodes transferred from Três Marias.

 

Notes: RLE stands for Roast-Leach-Electrowinning.

Alloys are zinc-based products with the addition of up to 1.0% of a specified metal, which are primarily used in the galvanizing market.

Special alloys are zinc-based products with addition of specified metals, which are primarily used in galvanizing market.

Zamac is a zinc-based product with the addition of specified metals, which are primarily used in the die casting market.

 

Smelter sales

 

We produce various kinds of refined zinc products. In 2020, we sold a total of 550.7 thousand tonnes of our metallic zinc line of products (including SHG, CGG jumbos, alloys, and Zamac). In addition, we commercialized 34.7 thousand tonnes of zinc oxide at 80.0% standard zinc content in 2020, totaling 585.4 thousand tonnes of zinc metal products sold.

 

Cajamarquilla

 

The Cajamarquilla smelter is located in the district of Lurigancho/Chosica in Lima, Peru, and is accessible by road.

 

The Cajamarquilla smelter is currently the largest zinc smelter in Latin America and the only zinc smelter in Latin America outside Mexico and Brazil, according to Wood Mackenzie. It uses the RLE process to produce metallic zinc. With an annual production capacity of 344.4 thousand tonnes of metallic zinc, the Cajamarquilla smelter produced 305.4 thousand tonnes of zinc metal available for sale in 2020. In recent years, Cajamarquilla developed operational efficiencies, including debottlenecking projects, which increased the production of calcine from concentrates obtained from Nexa Peru, and the use of calcine processed by third parties. See “Risk factors—Operational risks—Inadequate supply of zinc secondary feed materials and zinc calcine could affect the results of our smelters.”

 

The Cajamarquilla smelter produces zinc primarily from zinc concentrates and, to a lesser extent, recycled zinc secondary feeds (also referred to as pre-treated concentrate). In 2020, the Cajamarquilla smelter consumed approximately 322.5 thousand tonnes of zinc contained in concentrates. In 2020, 37.2% of the zinc contained in concentrates used by the Cajamarquilla smelter was sourced from our mines in Peru and 62.8% was purchased from third parties.

 

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Smelting Operations

 

In 2020, the Cajamarquilla smelter sold approximately 302,907 thousand tonnes of metallic zinc, of which 34.1% of the volume was sold to Latin America (including Mexico), 19.5% to Europe, 12.5% to the United States and Canada, 4.0% to international traders, 26.4% to Asia and 3.5% to Africa. The Cajamarquilla smelter also produces sulfuric acid, silver concentrate, copper cement and cadmium sticks. These products are sold primarily to international traders and local customers.

 

The following table presents the historical concentrates processed and zinc recovery rate in Cajamarquilla for the periods indicated.

 

    For the Year Ended December 31,    
    2020       2019       2018    
Input (in tonnes)                        
Zinc Contained in Concentrate from Our Mines     119,843       135,104       132,546  
Zinc Contained in Concentrate from Third Parties     202,687       230,938       215,132  
Secondary Raw Material     1,966              
Total Inputs     324,495       366,042       347,678  
Zinc Recovery (%)     93.7       94.1       93.8  

 

Brownfield project

 

Conversion to Jarosite process

 

In 2017, we announced our intention to convert our Cajamarquilla smelter to the Jarosite process, which would allow for the recovery of a greater percentage of zinc. The project was estimated to improve the zinc recovery rate by 3.0% at the Cajamarquilla smelter. We initiated the construction phase in 2018 and during 2019 civil works and procurement activities continued to progress. In December 2019, the implementation of the conversion process was suspended due to problems with contractors and suppliers. We intend to reassess the project throughout 2021. For more information about the financial impact of this suspension, see Note 23(b) to our consolidated financial statements.

 

Três Marias

 

The Três Marias smelter is located in the municipality of Três Marias in the state of Minas Gerais, Brazil, 250 km from the Morro Agudo mine and 253 km from the Vazante mine and is accessible by road.

 

The Três Marias smelter was built to treat the zinc silicate concentrates from the Vazante mine (willemite and calamine) and sulfide concentrates from the Morro Agudo mine, from Nexa Peru and from third-party concentrates. Currently, this smelter is integrated with the operations of the Vazante and Morro Agudo mines, and it uses the RLE process to produce metallic zinc and zinc oxide. The annual production capacity of our Três Marias smelter is 192.2 thousand tonnes of metallic zinc per year. Production in 2020 totaled 202.8 thousand tonnes of zinc metal available for sale.

 

The Três Marias smelter produces zinc primarily from zinc contained in concentrates and, to a lesser extent, recycled zinc secondary feeds. In 2020, this smelter consumed approximately 203.3 thousand tonnes of zinc contained in concentrates and 1.4 thousand tonnes of secondary raw material.

 

In 2020, Três Marias sold approximately 169.2 thousand tonnes of metallic zinc and 34.6 thousand tonnes of zinc oxide, of which 71.9 % of the volume was sold to Latin America (including Mexico), 3.1% to international traders, 11.2% to Africa, 4.5% to Asia, 4.1% to Europe and 5.3% to the United States. The Três Marias smelter also produces copper/cobalt cement and cadmium briquettes. These products are sold to local customers.

 

The Três Marias smelter contains a zinc oxide production plant intended for the chemical, pneumatic, ceramic, animal feed and fertilizer industries. In 2020, the production of zinc oxide was approximately 35.3 thousand tonnes. In zinc content, approximately 60.3% of the raw material was electrolytic zinc that originated from the melting stage. In addition, we purchased 39.7% of raw material from third parties, in the form of dross and skims, to produce zinc oxide as well as the generation of by-products.

 

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Smelting Operations

 

The following table presents the historical concentrates processed and zinc recovery rate in Três Marias for the periods indicated.

 

    For the Year Ended December 31,  
    2020     2019     2018  
Inputs (in tonnes)(1)                        
Zinc Contained in Concentrate from Our Mines     176,893       178,928       185,970  
Zinc Contained in Concentrate from Third Parties     26,403       22,470       16,483  
Secondary Raw Material     1,374       2,642       933  
Total Inputs     204,669       204,040       203,387  
Zinc Recovery (%)     94.8       94.3       93.7  

 

(1) Impacted by higher secondary raw material consumption and concentrates with contaminants (mainly iron and arsenic).

 

Juiz de Fora

 

The Juiz de Fora smelter is located in the municipality of Juiz de Fora in the state of Minas Gerais, Brazil, and is accessible by road.

 

The Juiz de Fora smelter produces zinc from sulfide concentrates and secondary sources such as EAF dust, batteries, and brass oxide, and uses the RLE process to produce metallic zinc. The annual production capacity of our Juiz de Fora smelter is 96.9 thousand tonnes of metallic zinc per year. In 2020, Juiz de Fora produced 79.4 thousand tonnes of zinc metal available for sale. In recent years, Juiz de Fora used calcine processed by third parties in its production process.

 

The Juiz de Fora smelter produces zinc from zinc concentrates and recycled zinc secondary feeds. In 2020, this smelter consumed 69.8 thousand tonnes of zinc contained in concentrates and 14.9 thousand tonnes of zinc from secondary raw material and secondary sources. This smelter also produces sulfuric acid, sulfur dioxide, silver concentrate and copper sulfate.

 

In 2020, the Juiz de Fora smelter sold approximately 78.6 thousand tonnes of metallic zinc, of which 94.1% of the volume was sold to Latin America (including Mexico), 0.8% was sold to Africa and 5.1% to international traders. The smelter operated at 60% of its normal production capacity in May and June, in anticipation of a lower market demand due to the global economic conditions due to the COVID-19 pandemic. Beginning in July, the Juiz de Fora smelter started to ramp up its operations, returning to normal production level during the second half of 2020.

 

The following table presents the historical concentrates processed and zinc recovery rate in Juiz de Fora for the periods indicated.

 

    For the Year Ended December 31,  
    2020     2019     2018  
Inputs (in tonnes)                        
Zinc Contained in Concentrate from Our Mines     22,291       39,125       45,537  
Zinc Contained in Concentrate from Third Parties     47,500       37,763       32,004  
Secondary Raw Material     14,925       16,367       19,165  
Total Inputs     84,716       93,255       96,706  
Zinc Recovery (%)     92.8       93.4       93.5  

 

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Other Operations

 

Other operations

 

Transportation and shipping

 

Concentrates in our mines

 

Our Cerro Lindo operation transports 100.0% of its concentrates by road. The concentrates are trucked in a dedicated fleet through the Panamericana Sur road to the port of Callao that is approximately 255 km north, or to the Cajamarquilla smelter. This transportation is covered by long-term contracts entered with two trucking companies.

 

Our Atacocha and El Porvenir operations use both road and rail transportation. The concentrates are trucked through the Carretera Central road to the port of Callao that is approximately 315 km west, or to the Cajamarquilla smelter. We also use railway transportation to secure logistic availability and maintain high environmental standards. Our use of railway transportation is covered by a long-term contract.

 

The zinc concentrate produced in the Cerro Lindo, Atacocha and El Porvenir mines supply both our Peruvian and Brazilian smelters, as well as third-party customers, while the lead and copper concentrates produced by these mines are transported to third-party customers from the port of Callao. Our smelters use zinc concentrate supplied from our mines and from third-party suppliers to meet the blending needs of each smelter.

 

The Peruvian zinc concentrate supplied to the Brazilian smelters is loaded in bulk 28,000 tonne shipments and sent to the Port of Rio de Janeiro, where it is cleared through customs and then loaded into railcars to the Juiz de Fora smelter or into trucks and railcars to the Três Marias smelter. The ocean freight for this Peruvian zinc is covered by a long-term freight contract.

 

All the zinc concentrates produced at our Vazante and Morro Agudo mines are transported by road to the Três Marias smelter using two trucking companies. These mines also produce lead and lead/silver concentrates, which are loaded into containers at the mine and are transported using trucks and trains to the Sepetiba Tecon Terminal in Itaguaí, Rio de Janeiro, Brazil. The lead and lead/silver concentrates are then shipped to customers in Asia in accordance with our annual contracts with container shipping lines.

 

Smelters

 

The metallic zinc produced in the Cajamarquilla smelter is transported by train or truck to the terminals. The material intended for the Peruvian domestic market is distributed by truck from these terminals, while exports to foreign markets are loaded into containers and transported by truck from these terminals to the port of Callao.

 

The metallic zinc produced in the Juiz de Fora and Três Marias smelters is transported by truck for either local customers or exports. In the case of exports, the material is transported to terminals near the ports of Rio de Janeiro or Itaguaí, both in the state of Rio de Janeiro, or the port of Santos, in the state of São Paulo. The material is then loaded into containers at the terminal and transported to the ports by truck, where it is shipped to customers abroad.

 

The metallic zinc and zinc oxide production process in our smelters also produces by-products. The most relevant by-products are sulfuric acid and silver concentrate. Sulfuric acid produced in the Cajamarquilla smelter is loaded into dedicated FCCA tank railcars and transported to be stored. The sulfuric acid is then loaded in bulk into chemical ship-tanks destined to our customers and discharged at the Chilean ports of Mejillones and Barquito. The silver concentrate produced in the Cajamarquilla and Juiz de Fora smelters is loaded into containers and are dispatched to the port of Callao in Peru or to the port of Itaguaí.

 

We ship all our refined zinc and silver concentrate exports in containers. Transportation of this material is covered by annual agreements with the liner shipping providers, which are responsible for 70.0% of these shipments.

 

Sales and marketing

 

We sell most of our products through supply contracts with terms between one and four years. Only a small portion of our products is sold on the spot market. The agreements with our customers include customary international commercial terms, such as CIF, FOB and other delivery terms based on Incoterms 2010/2020. Our ability to deliver significant volumes across several regions worldwide makes us a significant supplier to a client base of end users and global traders. As a result, we can obtain competitive commercial terms for our products in the long-term. In 2020, our top 10 metallic zinc customers represented approximately 41.9% of the total sales volume for such products, with our top 10 zinc oxide customers representing 65.6% of the total sales volume for that product, and our top three concentrate customers represented approximately 95% of the total sales volume for such products, in each case excluding intercompany sales.

 

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Other Operations

 

Concentrates

 

In 2020, the majority (approximately 99%) of our total production volume of zinc concentrates went to our smelting operations in Peru and Brazil. In 2020, we sold 1.4 thousand tonnes of zinc contained in concentrates produced from our Peruvian operations to third-party customers. Sales prices are established mainly by reference to prices quoted on the LME less a discount based on either the treatment charge or smelter charge. The LME price quotes are based on prevailing LME average prices for the period set forth in our sale agreements, and generally refer to either the month following the shipment or the period near the execution date of the relevant agreement.

 

We also purchase zinc contained in concentrate from third-party suppliers to meet our raw material requirements. In 2020, 52% of the total zinc raw material consumption in our smelters was produced by our mines and 48% was purchased from third parties or obtained from secondary raw materials.

 

Refined Metals

 

Our metallic zinc and zinc oxide are sold worldwide through our commercial offices located in:

 

· São Paulo, Brazil;

 

· Lima, Peru;

 

· Houston, United States; and

 

· Luxembourg, Grand Duchy of Luxembourg.

 

We hold a leadership position in our home market, Latin America (excluding Mexico), with a market share of 87.0% in 2020, according to our sales volume, import databases and demand forecasts sourced from specialized consultancy groups and customs websites. In other regions, we hold a strategic position, with market share of 29.5% in Africa, 4.2% in North America, 3.4% in Europe and 1.0% in Asia, according to our sales volumes, import databases and demand forecasts sourced from specialized consultancy groups and customs websites. In recent years, we have increased our sales of metallic zinc and zinc oxide to end users in attractive markets, consolidating a commercial network in place to support volume growth.

 

In 2020, 80.3% of our total sales of refined metals were to customers in the continuous galvanizing, general galvanizing, die casting, transformers and alloy segments and 19.7% of our total sales were to international traders. Our products are sold to end users in the transport, construction, infrastructure, consumer goods and industrial machinery industries. Of our volume of metallic zinc and zinc oxide sales in 2020, 55.3% were to Latin America (including Mexico), 11.5% to Europe, 8.3% to the United States and Canada, 5.8% to Africa and 15.2% to Asia, with the remaining 3.8% to international traders. Sales prices are mainly established by reference to prices quoted on the LME plus a negotiable premium. Pricing is based on prevailing LME average prices for a period set forth in our sale agreements, which generally refer to the month or month prior to shipment.

 

By-products

 

We sell a wide variety of chemical and metallurgic by-products generated during the production processes in our smelters and mines to a broad customer base. Our sales include more than 25 different by-products, most of which are sold based on the characteristics of each market or region.

 

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Other Operations

 

Power and energy supply

 

Peru

 

With respect to our Peruvian operating units, we obtained 97.5% (1,672 GWh) of the electricity for our operations from the SEIN and 2.5% (44 GWh) from our own hydroelectric power plants. We own three hydroelectric power plants, two at Atacocha and one at El Porvenir, with a total installed gross rated capacity of 10,568 kilowatts, or kW. We also received our energy from third parties through electricity supply contracts. Our Cerro Lindo, El Porvenir and Atacocha units have electricity supply contracts with Electroperú S.A., which cover 100% (241.41 GWh), 92.5% (94.2 GWh) and 40.7% (24.85 GWh) of their electricity requirements, respectively. In July 2019, we signed a new long-term energy agreement with Electroperú S.A, a well-known Peruvian state-owned company, which started supplying our operations in Peru in January 2020, totaling a supply of 1,672 GWh this year. In January 2020, the Cajamarquilla unit entered into an electricity spot supply contract with Engie Energía Perú S.A. (formerly Enersur S.A.), which expired in July 2020, totaling a supply of 20 GWh. Since then, Electroperú has been the sole supplier for our operations in Peru.

 

The following table sets forth the energy sources and electricity consumption with respect to our Peruvian operating units in 2020.

 

Operating Unit

 

Energy Source

 

Total Energy
Consumed in 2020
(GWh)
 

   

Percentage of Total
Energy Usage
in 2020

 
                 
Third Party                    
Cerro Lindo   Third Party (Electroperú S.A.)     241.4       13.9 %
El Porvenir   Third Party (Electroperú S.A.)     94.2       5.4 %
Atacocha   Third Party (Electroperú S.A.)     24.8       1.4 %
Cajamarquilla   Third Party (Engie Energía Perú S.A.)     19.9       1.1 %
Cajamarquilla   Third Party (Electroperú S.A.)     1,311.2       75.6 %
Total Energy Usage         1,691.6       97.5 %
Own Power Plant                    
El Porvenir   Own Power Plant (Candelaria)     7.6       0.4 %
Atacocha   Own Power Plant (Chaprin and Marcopampa)     36.2       2.1 %
Total Energy Usage         1,735.4       100 %

 

Hydroelectric plants

 

Candelaria

 

The El Porvenir unit has one hydroelectric plant, the Candelaria Hydroelectric Power Plant, which is located along the Lloclla River. The plant contains three separate hydroelectric turbines, two of which have been operational since 1957 and the third since 1998, and which together have an installed rated capacity of 4.2 MW. During 2020, El Porvenir consumed 7.6 GWh, which represented approximately 7.5% of the energy usage of the unit.

 

Chaprin and Marcopampa

 

The Atacocha unit has two hydroelectric plants. The Chaprin Hydroelectric Power Plant is located along the Lagia Ravine near the Huallaga River. The plant has been operating since 1953 and its installed rated capacity is 5.4 MW. The Marcopampa Hydroelectric Power Plant has been operating since 1937, and was overhauled in 1984, increasing its installed rated capacity of 1.0 MW. Since the beginning of 2020, Marcopampa has been shut off indefinitely. During 2020, Atacocha consumed 36.2 GWh from these plants, which represented approximately 59.3% of the energy usage of the mine.

 

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Other Operations

 

Brazil

 

With respect to our Brazilian operations, as of December 31, 2020, energy supply comes from various contracts, and our subsidiary Pollarix S.A (“Pollarix”).

 

The five hydroelectric plants in which our subsidiary Pollarix has directly or indirectly the following interests: a 21.0% equity participation in the consortium Enercan (Campos Novos hydroelectric power plant), a 100.0% ownership of the hydroelectric power plant Picada located in Minas Gerais, a 12.6% equity participation in the consortium Amador Aguiar I, a 12.6% equity participation in the consortium Amador Aguiar II and a 23.9% equity participation in the consortium Igarapava. These consortiums have hydroelectric power plants in the states of Minas Gerais, Santa Catarina and São Paulo. All hydroelectric power plants of Pollarix provide electricity to the four operating units (Vazante, Morro Agudo, Três Marias and Juiz de Fora).

 

The only activity of Pollarix is to own our energy assets and sell energy to our Brazilian operating subsidiaries at market prices. We own all the common shares of Pollarix, which represents 33.33% of its total share capital. The remaining shares are preferred shares with limited voting rights, which are owned by our shareholder VSA and/or its affiliates. Under the terms of the preferred shares, VSA is entitled to dividends per share equal to 1.25 times the dividends per share payable on the common shares. See “Operating and financial review and prospects—Overview—Key factors affecting our business and results of operations—Operating costs and expenses—Energy costs.”

 

We have a contract with Votorantim Energia, which provides energy from various sites, with a total of supply of 7.1 MW per year of energy with a reference price of R$221/MWh (price annually adjusted for inflation). During 2020, it provided electricity to the four operating units (Vazante, Morro Agudo, Três Marias and Juiz de Fora), and we intend to use this energy source for the Aripuanã operation.

 

In January 2020, we began a new long-term energy supply agreement with Furnas, a Brazilian energy company controlled by Eletrobras, to help address the increased electricity demand in our operations. Nexa Brazil currently consumes nearly all the energy supplied by Pollarix and Votorantim Energia in its existing operations. Furnas provides electricity exclusively to Três Marias unit, with 13.8MW per year of energy with a reference price of R$154/MWh (price will be annually adjusted for inflation). The agreement is valid for 15 years.

 

The following table sets forth our energy sources and consumption with respect to our Brazilian operations in 2020.

 

Operating Unit

 

Energy Source

 

Power Plant

 

Percentage of Pollarix
Ownership

   

Total Energy Consumed in 2020 (GWh)

   

Percentage of Total Energy Usage in 2020 

 
Morro Agudo, Vazante, Três Marias and Juiz de Fora   Enercan Consortium   Campos Novos     21.0 %     676.3       40.8 %
    Picada   Picada     100.0 %     265.0       16.0 %
    Amador Aguiar I   Amador Aguiar I     12.6 %     131.2       7.9 %
    Amador Aguiar II   Amador Aguiar II     12.6 %     131.2       7.9 %
    Votener   N/A     N/A       54.5       3.3 %
    Igarapava   Igarapava     23.9 %     277.7       16.8 %
Três Marias   Furnas   Furnas     N/A       121.1       7.3 %
Total Energy Usage               1,657       100 %

 

Hydroelectric plants

 

Campos Novos

 

Campos Novos is a hydroelectric plant located along the Canoas River. The plant has an installed capacity of 880 MW and has been authorized by the Brazilian Electricity Regulatory Agency (Agência Nacional de Energia Elétrica or ANEEL), to produce 377.90 MWavg. During 2020, the plant generated a total of 3,220.7 GWh. 21.0% of the total generation is allocated to our operating plants. During 2020, our Morro Agudo, Vazante, Três Marias and Juiz de Fora units consumed 676.3 GWh from Campos Novos, which represented approximately 40.8% of our total energy usage.

 

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Other Operations

 

Picada

 

Picada is a hydroelectric plant located along the Peixe River. The plant has an installed capacity of 50 MW and has been authorized by ANEEL to produce 30 MWavg. During 2020, our Morro Agudo, Vazante, Três Marias and Juiz de Fora units consumed 265.0 GWh, which represented 16.0% of our total energy usage.

 

Igarapava

 

Igarapava is a hydroelectric plant located along the Grande River. The plant has an installed capacity of 210 MW and has been authorized by ANEEL to produce 130.51 MWavg. During 2019, our Morro Agudo, Vazante, Três Marias and Juiz de Fora units consumed 277.7 GWh from Igarapava, which represented approximately 16.8% of our total energy usage.

 

Amador Aguiar I

 

Amador Aguiar is a hydroelectric plant located along the Araguari River. The plant has an installed capacity of 240 MW and has been authorized by ANEEL to produce 155 MWavg. During 2020, our Morro Agudo, Vazante, Três Marias and Juiz de Fora units consumed 131.2 GWh from Amador Aguiar I, which represented 7.9% of our total energy usage.

 

Amador Aguiar II

 

Amador Aguiar is a hydroelectric plant located along the Araguari River. The plant has an installed capacity of 210 MW and has been authorized by ANEEL to produce 131 MWavg. During 2020, our Morro Agudo, Vazante, Três Marias and Juiz de Fora units consumed 131.2 GWh from Amador Aguiar II, which represented 7.9% of our total energy usage.

 

Environmental, social and governance (“ESG”) and corporate initiatives

 

Through efficient and sustainable management, we are committed to operational excellence at all levels at Nexa and thus seek to create more value to our stakeholders. In 2019, we established a sustainability committee to oversee sustainability-related issues, which include the prioritization of safe and sustainable business practices, with respect to environmental, health, safety and social matters. In 2020, the sustainability committee also assumed oversight of capital projects. Its role expanded to monitor technical, economic and social issues with respect to our projects, including exploration, development, licensing, construction and operation of mines and metallurgical plants and key assets for our strategy and growth.

 

Following the principles established by the International Integrated Reporting Council (“IIRC”) and Global Reporting Initiative (“GRI”), in 2020 we revised the Nexa materiality matrix, which defines the issues that are most relevant to us and our stakeholders. We revised the matrix based on evaluating the most relevant topics for the mining and metals sector, the Sustainability Accounting Standards Board (“SASB”) guidelines for the mining and metals sector, as well as other sector benchmarks. These revisions also included, for the first time, a survey of external stakeholders. We have combined the results of these surveys with insights from our leadership teams to define the 12 material issues that are most relevant to us and to our stakeholders. By reviewing the material issues, we seek to guide our reporting and management strategies, considering the short, medium and long-term context, impacts, risks and opportunities of each issue.

 

As a result of the survey, in 2020 we revised our previous eight material topics relating to corporate goals and ESG management guidelines – waste and tailings management, climate change (formerly called emissions), water resources management, social management (formerly called local development), health, safety and wellness, plurality (formerly called people), decommissioning and human rights (which was excluded because the scope of this topic will be addressed by others material topics) – and added five new topics: dam management, innovation, ethics and compliance, operational excellence and reputation.

 

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Other Operations

 

Our twelve current material topics, including ESG initiatives, are further discussed below.

 

· Waste management (E). We aim to reduce our residue footprint. Our activities generate a significant amount of waste. We seek to reduce the generation of mining and metallurgical waste, complying with applicable local legislation, and acting in accordance with our strategic commitment, attempting to co-create a positive legacy for society. Our Morro Agudo site is considered a pioneer in eliminating waste production with one of the main projects being agricultural lime powder, also known as Zincal200. The project is based on technology created to reprocess the tailings produced in the zinc beneficiation process, which used to be dumped in dams. In addition, our Cerro Lindo and Vazante mines already use the dry stacking method for tailings disposal (and our Aripuanã project is also designed to use the same). Peru’s mining operating units have a significant volume of tailings disposed in the backfill system. Only 34.0% of the tailings generated by Nexa were disposed of in dams in 2020.

 

· Climate change (E). One of our commitments is to reduce greenhouse gas emissions in an effort to minimize our impact on climate change. We consume large amounts of energy due to the nature of our activities and transportation processes, which is why we seek new technologies and progress in sustainable energy generation. One of the highlights in energy efficiency was the implementation of a project for a biomass boiler at the Três Marias unit, in which fuel oil was substituted by eucalyptus wood chips and sugar cane bagasse. The boiler is owned by a supplier and is installed within the unit. Another important initiative is underway at the Cajamarquilla unit in Peru, which includes the substitution of diesel oil with natural gas, made viable through the implementation of a gas pipeline in the region. At the Juiz de Fora unit, we have an ongoing project to replace natural gas by reusing solid waste as fuel to generate steam. Almost all of the electric energy consumed by our operations is from renewable and low emission sources, predominantly hydroelectricity.

 

· Water resources management (E). Our target is to reduce water consumption and increase recirculation. Mining activity involves technical procedures in which water assumes an important role, both for extraction and processing, making it even more important to reduce water use and increase reuse throughout the value chain. Advanced investments in efficient water recirculation programs contribute not only to lowering the intake of new water but also reducing the volume of effluents and the environmental impact of the discharge. In 2020, we earmarked 17% of environmental spending resources towards efforts to keep our effluents disposed through proper treatment. In our Cerro Lindo mine, we have a high rate of water recirculation (about 90%). We use a desalination plant, extracting salt by a reverse osmosis process and pumping it up to a plant, at an altitude of 2,200 meters. In an area with scarcity of water resources, this technology is important to avoid competing with the local population in demand for water. In addition, we encourage and guide the community in the region to store rainwater.

 

· Dam management (E). Tailings disposals are one of the main risks associated with mining activity. We have safe tailings disposal practices, and we constantly review our dam management policy, which goes beyond the requirements of the legislation of the jurisdictions in which we operate. We apply guidelines from the ICOLD to control and monitor our 47 dams and tailings deposits (23 in Brazil and 24 in Peru). We also have 6 Golden Rules for Managing Dams and Tailings Sites, with mandatory compliance.

 

· Decommissioning (E). Our activities impact the environment and the communities in the vicinity of our units. As a way of minimizing these impacts, we seek to designate alternative future uses, with the goal of co-creating a positive legacy in neighboring communities, free of environmental liabilities. Some of our achievements include: the definition of general guidelines for decommissioning (governance and corporate committee for approval of new plans); assessment of future uses and preliminary liabilities valuation; integrated management of decommissioning cash flow; and review of our decommissioning plans and updated Asset Retirement Obligation (“ARO”) costs and liabilities. We also perform benchmark visits to assess best practices in decommissioning. For further details on our ARO and environmental obligations revisions, see Note 27 to our consolidated financial statements.

 

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Other Operations

 

We have developed decommissioning plans for all of our units which not only go beyond adopting best-practices and regulatory requirements from our operating markets (Peru and Brazil) but are also based on international standards from the EPA and Minerals Council of Australia (“MCA”), in addition to Environmental Resource Management consultants from Canada. These plans are developed at early stages of the projects, which are initially conceptual, and are revised and updated every five years or whenever there is a material change in the unit’s operations. In addition, we develop a technical execution plan to decommission two years prior to closure which is submitted to local authorities in Brazil, while in Peru the execution plan submission is defined when the EIA is approved.

 

· Social development (S). We aim to develop mutually beneficial relationships with the communities in which we operate. Nexa’s social strategy is aimed at leaving a long-lasting relevant legacy for local communities by contributing to the improvement of social indicators and the quality of life of the people living in the municipalities near our operations. Nexa’s social investments focus mostly on four levers for community improvement: economic diversification; childhood and youth; public administration and social participation; and socio-environmental development. Our achievements include the development and improvement of Nexa's social governance program. In addition, in 2020 we dedicated over 10 thousand hours to volunteer work across our units, benefitting more than 17 thousand people. We aim to develop our greenfield projects aligned with social best practices, like Aripuanã’s Socio-economic Integrated Plan and Bonsucesso’s Social Entrance Plan. We have conducted a sanitation diagnosis (water and sewage) in all communities surrounding our operations. In Aripuanã, we have a qualification program in place for future mine and operation plant professionals. In 2020, we had 248 candidates enrolled, of which approximately 104 received professional qualifications on maintenance and automation and geology and surveying. Of the total number of participants, 52.0% were women.

 

· Health, safety and wellness (S). Our goal is to reduce injury frequency rate and to reduce fatalities to zero. We continuously invest in strengthening a culture focused on safety and health for both our own as well as outsourced employees, through training, especially for risky activities, and in enhancing working conditions. We launched a quality-of-life program in 2016, seeking to emphasize the dimensions of integral health. We also have health initiatives in place for the Aripuanã project, aimed at disease prevention and a much healthier operating environment (i.e., Dust Zero Project). We also try to maintain the adequacy level of Nexa’s chemical management flow, which includes both the products used and produced. For further discussion of our safety records, please refer to "Health and safety compliance" in the following section. In response to the COVID-19 pandemic, we also created a Crisis Committee to carry out preventive and protective procedures in our operations and offices. For more information about the Crisis Committee, please see “Operating and Financial Review and Prospects—Operating costs and expenses—COVID-19.”

 

· Plurality (G). We target the increase of plurality in the workplace. Our personnel management model and our policies and tools have guided the development of people based on performance, enthusiasm and courage. For further information please see “Corporate Governance, management and employees—Board of directors— Diversity” section.

 

· Ethics and compliance (G). Acting responsibly and transparently is one of our core values. We are committed to high standards of ethics and integrity across the entire company, which are standards guaranteed through the Compliance Program. Our board of directors is one of the main agents in promoting the program and ensuring compliance with our code of conduct. Our code of conduct is a public document that is also shared with all stakeholders, including employees, suppliers, customers, communities, NGOs, government agencies, shareholders and other individuals and organizations with which we have a relationship. The code of conduct outlines an effective process for managing and mitigating risks, setting goals for us to achieve excellence in all our practices.

 

· Operational excellence. We seek continuous improvement in competitiveness to maximize the value of existing operations. We invest in projects that ensure we have operational stability, increased capacity utilization, constant cost improvement, productivity and rationalization of capital employed.

 

· Reputation. We want to stand out from our competitors and be recognized as one of the leading players of the mining of the future, through sustainable production and by co-creating a legacy for society.

 

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Other Operations

 

· Innovation: Enabling the strategic axes of growth and operational excellence makes our operations safer, minimizes waste and optimizes production. For four years, we have managed a powerful tool for open innovation, the Mining Lab platform, which allows us to deliver projects in energy, circular economy, IT and automation, in Brazil and Peru.

 

In 2021, we plan to define the indicators and goals for each material topic until 2030, providing further transparency with respect to our socio-environmental management goals, and how they align with our business strategy. Our sustainability approach is set out in our code of conduct and Compliance and Sustainability policies. We adhere to the United Nation’s Global Compact and the goals related to our material topics seek to contribute to fulfilling the UN’s Sustainable Development Goals (“SDGs”). Our current material topics and ESG initiatives strive to meet the SDGs.

 

Health and safety compliance

 

Health and safety in the workplace are among our highest priorities, and our policies and procedures seek to eliminate accidents. Nevertheless, mining is an activity that involves substantial risks. In 2017, following the unfortunate occurrence of seven fatalities at Nexa, we conducted a comprehensive review, and our board of directors approved a plan for Nexa’s Brazilian and Peruvian operations with three main safety related objectives: (i) prevent fatalities; (ii) reduce the frequency and severity of injuries; and (iii) improve safety culture, particularly in our Peruvian operations. It includes initiatives related to leadership development and training for our employees and third-party contractors, preventive procedures, such as digital mining, and an automation plan. This plan has facilitated the improvement of our health and safety indicators, including zero fatalities in 2018 and, unfortunately, one fatality in 2019.

 

Throughout 2020, we have reinforced the health and safety culture by creating a Master Plan that contains initiatives developed specifically for 2020 and other initiatives to be implemented over the next five years. Many of the 2020 initiatives, such as Global SIPAT (an internal week of discussion forums and seminars related to health and safety across our organization), Safety Workshops at all Nexa units (currently performed virtually due to the COVID-19 pandemic) and the PROA Movement (a year-end campaign by our safety department to promote prevention of work accidents), contribute to our enhanced safety culture. As a result of these actions and our leadership’s engagement in risk perception and management, in 2020 no work fatalities were registered in our operations in Brazil and Peru.

 

We have also sought to improve our safety record as it relates to recordable injury frequency, lost worktime incident, and severity rates, in conformity with standards in the mining industry. In 2020, our total recordable injury frequency rate was 2.40 compared to 2.15 in 2019 and 2.22 in 2018. This rate is defined as the number of injuries with and without lost time per one million man-hours worked. In 2020, our lost worktime incident rate was 0.79 compared to 0.75 in 2019 and 1.00 in 2018. This rate is defined as the number of injuries with lost time per one million man-hours worked. Our severity rate for 2020 was 178 compared to 149 in 2019 and 77 in 2018. To calculate the severity rate, we consider the sum of lost, transported and debited days, divided by the total number of man-hours worked times one million. In addition to these efforts, we also operate programs aimed at improving working conditions, including medical services, for our mining operations and monitoring employees’ health.

 

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Mineral Reserves and Resources

 

MINERAL RESERVES AND RESOURCES

 

Disclosure of Mineral Reserves and Resources

 

In October 2018, the Securities and Exchange Commission (“SEC”) adopted amendments to its current disclosure rules to modernize the mineral property disclosure requirements for mining registrants. The amendments include the adoption of S-K 1300, which will govern disclosure for mining registrants (the “SEC Mining Modernization Rules”). The SEC Mining Modernization Rules replace the historical property disclosure requirements for mining registrants that were included in the SEC’s Industry Guide 7 and better align disclosure with international industry and regulatory practices, including the Canadian National Instrument 43-101—Standards of Disclosure for Mineral Projects (“NI 43-101”). Although compliance with the SEC Mining Modernization Rules is not required until the fiscal year commencing on January 1, 2021, we have chosen to voluntarily comply with the SEC Mining Modernization Rules in this annual report.

 

For the meanings of certain technical terms used in this prospectus, see “Additional Information—Glossary.”

 

As a reporting issuer in Canada, we are also subject to NI 43-101, which is an instrument administered by the provincial and territorial securities regulatory authorities that governs how issuers in Canada disclose scientific and technical information about their mineral projects to the public. NI 43-101 imposes certain requirements in respect of such disclosure, including the requirement to have prescribed information prepared by, or under the supervision of, a qualified person and the filing of NI 43-101 technical reports in the prescribed circumstances. Any reference to a NI 43-101 report is for informational purposes only, and such reports are not incorporated herein by reference.

 

Descriptions in this report of our mineral deposits prepared in accordance with S-K 1300, as well as similar information provided by other issuers in accordance with S-K 1300, may not be comparable to similar information prepared in accordance with NI 43-101 that is presented elsewhere outside of this report. Please refer to the Technical Report Summaries filed as exhibits hereto for additional information with respect to our material properties.

 

Disclosures of mineral reserves and resources in this report have not been adjusted to reflect our ownership interest of the entities that ultimately own the assets. The information includes each mine, smelter and project of our consolidated subsidiaries, presented as a whole; however, we do not own undivided equity interests in certain of these mines and projects.

 

The qualified persons that have reviewed and approved the scientific and technical information contained in this annual report are identified in the footnotes to the tables summarizing the mineral reserves and resources estimates below, see “Information on the Company—Mining operations” below. For the meanings of certain technical terms used in this report, see “Additional information—Glossary.”

 

Presentation of information concerning Mineral Reserves

 

The estimates of proven and probable reserves at our mines and projects and the estimates of mine life included in this annual report have been prepared by the qualified persons referred to herein, and in accordance with the technical definitions established by the SEC. Under S-K 1300:

 

· Proven mineral reserves are the economically mineable part of a measured mineral resource and can only result from conversion of a measured mineral resource.

 

· Probable mineral reserves are the economically mineable part of an indicated and, in some cases, a measured mineral resource.

 

· Indicated mineral resource is that part of a mineral resource for which quantity and grade or quality are estimated on the basis of adequate geological evidence and sampling. The level of geological certainty associated with an indicated mineral resource is sufficient to allow a qualified person to apply modifying factors in sufficient detail to support mine planning and evaluation of the economic viability of the deposit. Because an indicated mineral resource has a lower level of confidence than the level of confidence of a measured mineral resource, an indicated mineral resource may only be converted to a probable mineral reserve.

 

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· Inferred mineral resource is that part of a mineral resource for which quantity and grade or quality are estimated on the basis of limited geological evidence and sampling. The level of geological uncertainty associated with an inferred mineral resource is too high to apply relevant technical and economic factors likely to influence the prospects of economic extraction in a manner useful for evaluation of economic viability. Because an inferred mineral resource has the lowest level of geological confidence of all mineral resources, which prevents the application of the modifying factors in a manner useful for evaluation of economic viability, an inferred mineral resource may not be considered when assessing the economic viability of a mining project, and may not be converted to a mineral reserve.

 

· Measured mineral resource is that part of a mineral resource for which quantity and grade or quality are estimated on the basis of conclusive geological evidence and sampling. The level of geological certainty associated with a measured mineral resource is sufficient to allow a qualified person to apply modifying factors, as defined in S-K 1300, in sufficient detail to support detailed mine planning and final evaluation of the economic viability of the deposit. Because a measured mineral resource has a higher level of confidence than the level of confidence of either an indicated mineral resource or an inferred mineral resource, a measured mineral resource may be converted to a proven mineral reserve or to a probable mineral reserve.

 

We periodically revise our reserves and resources estimates when we have new geological data, economic assumptions or mining plans. During 2020, we performed an analysis of our reserves and resources estimates for certain operations, which is reflected in new estimates as of December 31, 2020. Reserves and resources estimates for each operation assume that we either have or expect to obtain all the necessary rights and permits to mine, extract and process mineral reserves or resources at each mine. Where we own less than 100% of the operation, reserve estimates have not been adjusted to reflect our ownership interest. Certain figures in the tables, discussions and notes have been rounded. For a description of risks relating to our estimates of mineral reserves and resources, see “Risk factors—Risks related to our Mineral Reserves and Resources.”

 

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Mineral Reserves

 

The following table shows our estimates of Mineral Reserves for our material mining properties as of December 31, 2020 (unless otherwise indicated below) prepared in accordance with Subpart 1300 of Regulation S-K. The Morro Agudo mine, Atacocha underground mine and Atacocha open pit mine do not have known Mineral Reserves under Subpart 1300 of Regulation S-K.

 

    Grade     Contained Metal Content  
    Ownership Interest(1)         Total     Zinc     Copper     Silver     Lead     Gold     Zinc     Copper     Silver     Lead     Gold  
    (%)     Class     (Mt)     (%)     (%)     (g/t)     (%)     (g/t)     (kt)     (kt)     (koz)     (kt)     (koz)  
              Proven       29.37       1.71       0.60       20.9       0.23       -       501.5       177.3       19,702       66.1       -  
Cerro Lindo Mine(2)     80.16       Probable       22.73       1.08       0.62       21.6       0.18       -       246.4       141.8       15,770       40.0       -  
              Subtotal       52.10       1.44       0.61       21.2       0.20       -       747.9       319.1       35,472       106.1       -  
              Proven       3.76       3.76       0.25       62.9       0.98       -       141.3       9.5       7,602       36.9       -  
El Porvenir Mine(3)     80.16       Probable       10.09       3.74       0.22       62.8       0.85       -       377.6       22.4       20,364       85.5       -  
              Subtotal       13.85       3.75       0.23       62.8       0.88       -       518.9       31.9       27,966       122.4       -  
              Proven       8.44       8.40       -       15.2       0.24       -       708.8       -       4,125       20.6       -  
Vazante(4)     100       Probable       8.24       8.83       -       12.2       0.21       -       727.9       -       3,241       17.4       -  
              Subtotal       16.68       8.61       -       13.7       0.23       -       1,436.7       -       7,367       38.0       -  
              Proven       10.08       3.74       0.31       36.0       1.39       0.29       376.7       31.3       11,676       140.1       94.5  
Aripuaapnã(5)     100       Probable       13.42       3.60       0.21       32.9       1.33       0.33       483.1       28.4       14,211       178.9       141.5  
              Subtotal       23.51       3.66       0.25       34.3       1.36       0.31       859.8       59.7       25,887       319.0       236.1  
                                                                                                         
              Proven       51.65       3.35       0.42       26.0       0.51       0.06       1,728.2       218.0       43,105       263.7       94.5  
Total             Probable       54.49       3.37       0.35       30.6       0.59       0.08       1,835.2       192.6       53,586       321.8       141.5  
              Total       106.14       3.36       0.39       28.3       0.55       0.07       3,563.4       410.7       94,691       585.5       236.1  

 

 

 

Notes:

 

* Numbers may not add due to rounding.

 

(1) The Mineral Reserve estimates with respect to our mines have been prepared by the qualified persons referred to herein. The production and content amounts presented in this table have not been adjusted to reflect our ownership interest. The information presented in this table includes 100% of the mineral reserve estimates for the property. Please refer to our ownership percentage for the amounts attributable to our ownership interest in the property.

 

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(2) Subpart 1300 of Regulation S-K definitions were followed for Mineral Reserves, which also are consistent with the CIM (2014) definitions. The qualified person for Mineral Reserves is SLR Consulting, an independent mining consulting firm. Mineral Reserves are estimated at NSR cut-off values of US$33.56/t processed for SLS and US$49.90/t processed for C&F. A number of incremental stopes (down to US$26.16/t NSR value) are included in the estimate. Mineral Reserves are estimated using average long-term metal prices of Zn: US$2,494.90/t (US$1.13/lb); Pb: US$1,956.00/t (US$0.89/lb); Cu: US$6,457.90/t (US$2.93/lb); and Ag: US$16.85/oz, and metallurgical recoveries are based on recovery curves derived from historical processing data. A minimum mining width of 5.0 m and 4.0 m was used for SLS stopes and C&F stopes, respectively. Bulk density varies depending on mineralization domain.

 

(3) Subpart 1300 of Regulation S-K definitions were followed for Mineral Reserves, which also are consistent with the CIM (2014) definitions. The qualified person for Mineral Reserves is SLR Consulting, an independent mining consulting firm. Mineral Reserves are estimated at NSR cut-off values that are calculated per zone and mining method. For the C&F mining method, the values vary from US$59.75/t at the lower zone to US$63.37/t at the deepening zone. For SLS, the values vary from US$56.44/t at the lower zone to US$60.06/t at the deepening zone. Mineral Reserves are estimated using average long-term metal prices of Zn: US$2,494.90/t (US$1.13/lb); Pb: US$1,956.00/t (US$0.89/lb); Cu: US$6,457.90/t (US$2.93/lb); and Ag: US$16.85/oz, and metallurgical recoveries are based on recovery curves derived from historical processing data. Minimum mining width of 5.0 m were applied. Average Bulk density of 3.12 t/m3.

 

(4) Subpart 1300 of Regulation S-K definitions were followed for Mineral Reserves, which also are consistent with the CIM (2014) definitions. The qualified person for Mineral Reserves is SLR Consulting, an independent mining consulting firm. Mineral Reserves are estimated at a cut-off NSR value of US$47.49/t processed. Mineral Reserves are estimated using average metal prices of Zn: US$2,494.90/t; Pb: US$1,956.00/t; and Ag: US$16.85/oz (using an average long term U.S. dollar to Brazilian real exchange rate of 4.84), and metallurgical recoveries are based on recovery curves derived from historical processing data. A minimum mining width of 4 m was applied. Average Bulk density of 3.1 t/m3

 

(5) Subpart 1300 of Regulation S-K definitions were followed for Mineral Reserves, which also are consistent with the CIM (2014) definitions. The qualified person for Mineral Reserves is SLR Consulting, an independent mining consulting firm. Mineral Reserves are estimated at a NSR cut-off value of US$45.00/t processed. Some incremental material with values between US$40/t and US$45/t was included. Mineral Reserves are estimated using average long-term metal prices of Zn: US$2,494.90/t (US$1.13/lb); Pb: US$1,956.00/t (US$0.89/lb); Cu: US$6,457.90/t (US$2.93/lb); Ag: US$16.85/oz; and Au: US$ 1,538/oz, and metallurgical recoveries are based metallurgical testworks. A minimum mining width of 4.0 m was applied. Mineral Reserves are reported within engineered stope outlines assuming the following underground mining methods: bench stoping and VRM. Dilution and mining recovery are considered. The estimation of mineral reserves in this table is as of September 30, 2020.

 

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Mineral Resources

 

The following table shows our estimates of Mineral Resources for our material mining properties as of December 31, 2020 (unless otherwise indicated below) prepared in accordance with Subpart 1300 of Regulation S-K.

 

                Grade     Contained Metal  
    Ownership           Tonnage     Zinc     Copper     Silver     Lead     Gold     Zinc     Copper     Silver     Lead     Gold  
    Interest(1) (%)     Class     (Mt)     (%)     (%)     (g/t)     (%)     (g/t)     (kt)     (kt)     (koz)     (kt)     (koz)  
Cerro Lindo Mine(2)     80.16 %     Measured       4.40       2.00       0.67       19.6       0.20               87.8       29.4       2,774       8.8          
              Indicated       3.46       1.37       0.45       25.0       0.25               47.3       15.5       2,776       8.8          
              Subtotal       7.86       1.72       0.57       22.0       0.22               135.1       44.9       5,550       17.6          
              Inferred       8.71       1.28       0.33       31.2       0.35               111.1       29.1       8,748       30.6          
El Porvenir Mine(3)     80.16 %     Measured       0.23       2.59       0.23       63.5       0.99               6.0       0.5       471       2.3          
              Indicated       1.33       2.93       0.20       63.3       0.89               39.0       2.6       2,715       11.9          
              Subtotal       1.56       2.87       0.20       63.4       0.91               45.0       3.2       3,186       14.2          
              Inferred       8.47       3.60       0.23       78.4       0.95               305.0       19.8       21,345       80.8          
Vazante Mine(4)     100.00 %     Measured       3.40       6.91               8.4       0.18               235.0               918       6.2          
              Indicated       2.88       6.84               5.6       0.14               197.3               523       4.0          
              Subtotal       6.28       6.88               7.1       0.16               432.3               1,441       10.2          
              Inferred       13.85       6.86               9.5       0.18               950.2               4,216       25.6          
Aripuanã Project(5)     100.00 %     Measured       2.92       2.50       0.38       29.8       0.93       0.29       72.9       11.1       2,795       27.3       27.4  
              Indicated       5.17       1.86       0.27       18.2       0.63       0.43       96.3       13.9       3,021       32.4       71.0  
              Subtotal       8.09       2.09       0.31       22.4       0.74       0.38       169.2       25.1       5,816       59.7       98.4  
              Inferred       39.45       3.31       0.33       33.8       1.22       0.58       1,306.6       131.3       42,906       482.1       736.5  
Total             Measured       10.95       3.67       0.38       19.8       0.41       0.08       401.8       41.1       6,959       44.6       27.4  
              Indicated       12.84       2.96       0.25       21.9       0.46       0.17       379.9       32.1       9,034       57.1       71.0  
              Subtotal       23.79       3.29       0.31       20.9       0.43       0.13       781.1       73.2       15,993       101.7       98.4  
              Inferred       70.49       3.79       0.26       34.5       0.89       0.32       2,672.9       180.2       77,215       619.1       736.5  

 

 

Notes:

 

* Numbers may not add due to rounding.

 

* The estimation of Mineral Resources involves assumptions about future commodity prices and technical mining matters. Mineral Resources are reported exclusive of those Mineral Resources that were converted to Mineral Reserves, and Mineral Resources are not Mineral Reserves and do not have demonstrated economic viability.

 

85

 

 

Mineral Reserves and Resources

 

(1) The Mineral Resources estimate with respect to our mines were prepared by Nexa Resources and in certain cases validated by independent consultants. The tonnage and content amounts presented in this table represents 100% of the Mineral Resources estimates for the property. Please refer to our ownership percentage for the amounts attributable to our ownership interest in the property.

 

(2) Subpart 1300 of Regulation S-K definitions were followed for Mineral Resources which also are consistent with the CIM (2014) definitions. . The qualified person for Mineral Resources is SLR Consulting, an independent mining consulting firm. Mineral Resources are estimated at a NSR cut-off value of US$33.56/t for (SLS and US$49.90/t for C&F. Mineral Resources are estimated using an average long-term metal prices of Zn: US$2,869.14/t (US$1.30/lb); Pb: US$ 2,249.40/t (US$1.02/lb); Cu: US$7,426.59/t (US$3.37/lb), and Ag: US$19.38/oz, and metallurgical recoveries are based on recovery curves derived from historical processing data. A minimum mining width of 5.0 m and 4.0 m was used to create SLS and C&F resource shapes respectively. Bulk density varies depending on mineralization domain.

 

(3) Subpart 1300 of Regulation S-K definitions were followed for Mineral Resources, which also are consistent with the CIM (2014) definitions. The qualified person for Mineral Resources is SLR Consulting, an independent mining consulting firm. Mineral Resources are estimated at NSR cut-off values of US$60.06/t for the upper zone, US$61.09/t for the intermediate zone, US$59.75/t for the lower zone, and US$63.37/t for the mine deepening zone for C&F resource shapes. Mineral Resources are estimated using an average long-term metal prices of Zn: US$2,869.14/t (US$1.30/lb); Pb: US$2,249.40/t (US$1.02/lb); Cu: US$7,426.59/t (US$3.37/lb); and Ag: US$19.38/oz, and metallurgical recoveries are based on recovery curves derived from historical processing data. A minimum mining width of 4.0 m was used for C&F resource stopes. Bulk density varies depending on mineralization domain.

 

(4) Subpart 1300 of Regulation S-K definitions were followed for Mineral Resources, which also are consistent with the CIM (2014) definitions. The qualified person for Mineral Resources is SLR Consulting, an independent mining consulting firm. Mineral Resources are reported within underground mining shapes with minimum mining width of 3.0 m for willemite mineralization. Density was assigned based on rock type. Mineral Resources are estimated at various NSR cut-off values appropriate to the mineralization style. Mineral Resources are estimated using an average long-term metal prices of Zn: US$2,869.14/t (US$1.30/lb); Pb: US$ 2,249.40/t (US$1.02/lb) and Ag: US$19.38/oz oz (using an average long-term U.S. dollar to Brazilian real exchange rate of 4.84), and metallurgical recoveries are based on recovery curves derived from historical processing data.

  

(5) Subpart 1300 of Regulation S-K definitions were followed for Mineral Resources, which also are consistent with the CIM (2014) definitions. The qualified person for Mineral Resources is SLR Consulting, an independent mining consulting firm. Mineral Resources are reported using a US$45/t cut-off value for transversal longhole mining and longitudinal longhole retreat areas and US$55/t cut-off value for C&F areas. Mineral Resources are estimated using an average long-term metal prices of Zn: US$2,869/t (US$1.30/lb); Pb: US$ 2,249/t (US$1.02/lb); Cu: US$7,427/t (US$3.37/lb); Au: US$1,768/oz and Ag: US$19.38/oz, and metallurgical recoveries are based on metallurgical testworks. The Mineral Resources in this table have an effective date as of September 30, 2020.

 

86

 

 

Mineral Reserves and Resources

 

The following table shows our estimates of Mineral Resources for our other operating mines which do not currently have estimated Mineral Reserves as of December 31, 2020 prepared in accordance with Regulation S-K 1300.

 

                          Grade                 Contained Metal              
    Ownership         Tonnage     Zinc     Silver     Lead     Gold     Zinc     Silver     Lead     Gold  
    (%)(1)     Class   (Mt)     (%)     (g/t)     (%)     (g/t)     (kt)     (koz)     (kt)     (koz)  
Atacocha (Underground Mine)(2)     72.94 %   Measured     3.47       4.83       100.0       1.97               167.2       11,141       68.4          
            Indicated     4.04       4.13       73.4       1.39               166.8       9,527       56.0          
            Subtotal     7.50       4.45       85.7       1.66               334.1       20,669       124.3          
            Inferred     7.71       4.45       81.6       1.26               342.8       20,236       97.2          
Atacocha (Open pit Mine)(3)     72.94 %   Measured     4.34       1.17       30.0       0.87       0.22       50.6       4,191       37.7       31.2  
            Indicated     5.53       1.03       30.0       0.89       0.21       57.2       5,336       49.4       36.7  
            Subtotal     9.87       1.09       30.0       0.88       0.21       107.9       9,527       87.2       67.9  
            Inferred     1.31       0.97       30.5       0.83       0.26       12.8       1,291       10.9       10.9  
Morro Agudo Mine(4)     100.00 %   Measured                                                                        
            Indicated     17.28       3.25               0.64               561.7               111.1          
            Subtotal     17.28       3.25               0.64               561.7               111.1          
            Inferred     4.70       3.27               0.52               154.0               24.3          
Total           Measured     7.81       2.79       61.1       1.36       0.12       217.9       15,333       106.1       31.2  
            Indicated     26.84       2.93       17.2       0.81       0.04       785.8       14,864       216.5       36.7  
            Subtotal     34.65       2.90       27.1       0.93       0.06       1,003.7       30,196       322.6       67.9  
            Inferred     13.73       3.71       48.8       0.96       0.02       509.6       21,527       132.4       10.9  

  

 

Notes:

 

* Numbers may not add due to rounding.

 

* The estimation of Mineral Resources involves assumptions about future commodity prices and technical mining matters. Mineral Resources are not mineral reserves and do not have demonstrated economic viability.

 

87

 

 

Mineral Reserves and Resources

 

(1) The Mineral Resources estimate with respect to our mines were prepared by Nexa Resources. The tonnage and content amounts presented in this table represents 100% of the Mineral Resources estimates for the property. Please refer to our ownership percentage for the amounts attributable to our ownership interest in the property.

 

(2) Subpart 1300 of Regulation S-K definitions were followed for Mineral Resources, which also are consistent with the CIM (2014) definitions. The qualified person for the Mineral Resources estimate is José Antonio Lopes, B.Geo., MAusIMM (CP) Geo, a Nexa Resources employee. Mineral Resources are estimated at a net smelter return (NSR) cut-off value of US$ 55.05/t for C&F mining method. Mineral Resources are estimated using an average long-term metal prices of Zn: US$2,869.14/t (US$1.30/lb); Pb: US$2,249.40/t (US$1.02/lb); and Ag: US$19.38/oz, and metallurgical recoveries are based on recovery curves derived from historical processing data. A minimum mining width of 4.0 m was used for C&F resource stopes.

 

(3) Subpart 1300 of Regulation S-K definitions were followed for Mineral Resources, which also are consistent with the CIM (2014) definitions. The qualified person for the Mineral Resources estimate is José Antonio Lopes, B.Geo., MAusIMM (CP) Geo, a Nexa Resources employee. Mineral Resources are reported within optimized pit shell. Density was assigned based on rock type. Mineral Resources are estimated at a NSR cut-off value of US$19.46/t processed. Mineral Resources are estimated using an average long-term metal prices of Zn: US$2,869.14/t (US$1.30/lb); Pb: US$2,249.40/t (US$1.02/lb); Au: US$1,768/oz; and Ag: US$19.38/oz, and metallurgical recoveries are based on recovery curves derived from historical processing data.

 

(4) Subpart 1300 of Regulation S-K definitions were followed for Mineral Resources, which also are consistent with the CIM (2014) definitions. The Qualified Person for the Mineral Resources estimate is José Antonio Lopes, B.Geo., MAusIMM (CP) Geo, a Nexa Resources employee. Mineral Resources are reported within underground mining shapes. A minimum thickness of 3 m was applied for Bonsucesso and 4.5 m for Morro Agudo underground. Density was assigned based on rock type. The NSR cut-off values are calculated based on the life of mine costs for each mine. Morro Agudo: US$ 37.95/t and Bonsucesso: US$ 46.22/t. Mineral Resources are estimated using an average long-term metal prices of Zn: US$2,869.14/t (US$1.30/lb) and Pb: US$2,249.40/t (US$1.02/lb); and metallurgical recoveries are based on historical processing data and metallurgical testworks.

 

88

 

 

Mineral Reserves and Resources 

 

Internal Controls Disclosure

 

Nexa has used well-established quality assurance/quality controls (“QA/QC”) protocols since 2007 for core samples from operating mines and its Brownfield/Greenfield projects. Nexa has used a corporate database (GDMS Fusion) from Datamine since 2017, which replaced the previous corporate database system used from 2007 to 2016. The current database system has several default laboratory packages, specific for different Business Units (ore deposit types/countries) with pre-defined preparation and assay methods, reporting units and over-limit methods. All assay dispatches from all mines and projects follows the same protocols for each medium type (core, rock, soil, stream sediment samples). All written protocols are in a corporate internal system that requires revisions and updates every three years.

 

Nexa Quality Control include three types of duplicates (pulp, coarse rejects and half core duplicates), blank controls and certified standards. Inter-laboratory checks are also carried out on an annual basis at certified laboratories. Fusion database has a collection of pre-defined QA/QC charts for each type of control where Nexa parameters for each control are built in. All blanks and certified standards are approved and registered in Fusion by the database administrator. Nexa protocols for construction and certification of new standards from operating mines and projects include a minimum of ten laboratories and minimum of five samples per lab in the Round Robin. Laboratories need to be form different continents and only three laboratories from the same group are allowed.

 

Every mine and advanced project provides a detailed QA/QC report at least once a year, which is appended to the updated mineral resources technical reports prepared by our engineers.

 

With respect to verification of analytical procedures, Nexa retains an independent consultant to review Nexa’s QA/QC programs to ensure that an adequate level of quality is maintained in the process of sampling, preparing, and assaying the drill core samples and that the QA/QC programs have been designed and implemented to prevent or detect contamination and allow analytical precision and accuracy to be quantified. SLR completed this review for Nexa’s material projects in 2020 and found Nexa’s QA/QC programs meet or exceed industry standards.

 

Internally, regular data verification workflows are carried out to ensure the collection of reliable data. Coordinates, core logging, surveying, and sampling are monitored by exploration, mine geologists, and verified routinely for consistency.

 

The Mineral Resource and Mineral Reserve estimates are supported by a review of the recent operation results including operating costs, production, metallurgical performance and reconciliation. The LOM plan supporting the estimates includes consideration of changes to the permits required, capital costs, tailings capacity and other production constraints. The estimates are subject to normal industry risks including metal prices, metallurgical performance and geological modeling. For geological risk Nexa has modeling and estimation procedures following mining industry best practices including drilling, borehole survey, core logging, sampling, and density protocols.

 

89

 

 

Capital Expenditures

 

Capital expenditures

 

Our capital expenditures from January 1, 2018 through December 31, 2020 totaled US$1,046.5 million and we have budgeted US$450 million for 2021 for investments in projects that are currently underway, reflecting a 34% increase compared to our 2020 investment. The following table sets forth our capital expenditures for the periods indicated.

 

 

For the Year Ended
December 31,

 

2020

 

2019

 

2018

 

    (in millions of US$)  
Capital Expenditures                        
Expansion (1)     221.7       188.5       90.5  
Modernization     8.1       18.5       15.0  
Sustaining (2)     107.5       138.0       90.2  
Health, Safety and Environment (“HSE”)     16.2       57.4       89.1  
Others     1.3       7.7       11.7  
Subtotal     354.8       410.1       296.5  
Reconciliation to Financial Statements (3)     (18.3 )     0.2       3.2  
Total     336.5       410.3       299.7  

 

 

(1) For a description of the projects, see “Information on the Company—Mining operations.”
(2) Since 2Q20, investments in disposals facilities moved from HSE to Sustaining expenses.
(3) The amounts under “Reconciliation to Financial Statements” are mainly related to tax credit.

 

Our main capital expenditures during the years ended December 31, 2020, 2019 and 2018 include the following.

 

· In 2020, our capital expenditures were US$336.5 million, an 18% decrease compared to 2019, mainly due to effects of the COVID-19 pandemic and our decision to reduce exploration projects and maintain only essential investments (non-expansion), with the exception of Aripuanã. In 2020, 66% of our capital expenditures related to the construction of Aripuanã (US$187 million), as well as the Vazante mine deepening project (US$13 million), which aims to extend the life of mine by seven years.

 

· In 2019, our capital expenditures were US$410.3 million, mainly allocated to the following projects: the continuation of construction at the Aripuanã greenfield project; the Vazante mine deepening project; sustaining capital expenditures; and the construction of our dry-stacking tailings disposal facility in Vazante.

 

· In 2018, our capital expenditures were US$299.7 million, mainly allocated to the following projects: the Vazante life of mine extension; implementation of dry stacking tailings disposal at Vazante; the start of construction at the Aripuanã greenfield project; and the change from the Goethite conversion process to the Jarosite conversion process at Cajamarquilla. In addition, we also invested in non-expansion projects related to environmental, health and safety, sustaining, and investments in tailings dams.

 

For 2021, we have budgeted US$450 million to invest in projects that are currently underway. Our main projects include US$237 million directed towards expansion projects, of which US$232 million is allocated to construction of the Aripuanã project and US$2 million to the Vazante mine deepening project, and US$213 million towards mainly to sustaining and HSE investments.

 

We expect to meet these capital expenditure needs from our operating cash flow and our current cash position. We may need to incur indebtedness to finance a portion of these expenditures or also incur indebtedness if financing is available at attractive terms. Our actual capital expenditures may vary from the expected amounts we have described here, both in terms of the aggregate capital expenditures we incur and when we incur them.

 

90

 

 

Regulatory Matters

 

Regulatory matters

 

We are subject to a wide range of governmental regulation in the jurisdictions in which we operate. The following discussion summarizes the kinds of regulation that have the most significant impact on our operations.

 

Brazilian regulatory framework

 

Mining rights and regulation of mining activities

 

Mining activities in Brazil are governed by the Brazilian Federal Constitution of 1988, the Brazilian Mining Code and other decrees, laws, ordinances and regulations, such as the Decree nº 9.406/2018 which renewed the regulation of the Mining Code. These regulations impose several obligations on mining companies relating to, among other things, the way mineral deposits are exploited, the health and safety of workers and local communities where mines are located, and environmental protection and remediation measures. They also set forth the Brazilian federal government’s jurisdiction over, and scope of activities within, the industry. The MME and ANM regulate mining activities in Brazil. As of July 2017, the ANM replaced the National Department of Mineral Production (“DNPM”), and is responsible for monitoring, analyzing and promoting the performance of the Brazilian mineral economy, granting rights related to the exploration and exploitation of mineral resources and other related activities in Brazil.

 

Under the Brazilian Federal Constitution, surface property rights are distinct from mineral rights, which belong exclusively to the Brazilian federal government, the sole entity responsible for governing mineral exploration and mining activity in Brazil.

 

Summary of Brazilian concessions

 

In Brazil, we hold 741 exploration licenses (autorizações de pesquisa), 17 mining concessions (concessões de lavra), 24 mining concession applications (requerimento de lavra) and 116 exploration licenses applications (requerimentos de pesquisa), which we broadly and collectively refer herein to as mineral rights, that cover a total area of 2,404,795.5 hectares, of which: (i) 2,146,463.2 hectares, or 82.5%, are exploration licenses, (ii) 9,875.9 hectares, or 1.9%, are mining concessions, (iii) 14,761.9 hectares, or 2.7%, are mining concession applications and (iv) 233,694.5 hectares, or 12.9%, remain as exploration license applications and are presently under initial geological reconnaissance.

 

The term of each of the mining concessions mentioned above is valid for the life of the mine, evaluated pursuant to the specific mining project. All our mineral rights in Brazil are in good standing. Maintaining our mineral rights in Brazil in good standing involves: (i) maintaining production on the mineral concessions and/or satisfying the ANM’s requirements if production has been suspended; (ii) developing exploration work and paying an annual property fee for the exploration authorizations; and (iii) complying with all the legal requirements, including not only as to mining, but also as to environmental and real estate requirements applicable to claiming a property with respect to exploration applications.

 

Failure to pay the applicable fees for any given year will result in us forfeiting our mineral rights. As of December 31, 2020, we have paid all applicable royalties, taxes and fees on our mineral rights. Our mineral rights in Brazil that are not currently undergoing exploration or production will not expire unless we fail to timely pay the applicable royalties, taxes and fees, as well as the applicable penalties and meet the ANM’s and environmental authorities’ requirements, as applicable. See “Information on the Company—Regulatory matters—Brazilian regulatory framework—Royalties and other taxes on mining activities.”

 

The following table summarizes our mineral rights in Brazil.

 

91

 

 

Regulatory Matters

 

        Mineral Right  
    Project   Titles     Area (hectares)  
Mines   Morro Agudo / Ambrósia Trend     6       3,941.9  
    Vazante mine     8       2,091.1  
Greenfield Projects   Aripuanã     14       3,639.9  
    Caçapava do Sul     3       2,947.3  
Prospective Projects   Various     880       2,392,175.3  
Total         898       2,404,795.5  

 

Exploration authorization and mining concession regimes

 

Exploration authorizations grant the rights to conduct exploration activities for a period from one to three years, which may be renewable for an additional period (and potentially additional renewals on a case-by-case basis). Exploration authorizations are granted on a first come, first serve basis, and the ANM will only grant one exploration authorization for any given area. Mining concessions are currently valid until the mineral deposit reserves are exhausted. Mining concessions may be transferred to eligible third parties with the ANM’s prior approval, pursuant to applicable legislation.

 

Decommissioning

 

In Brazil, enterprises dedicated to the exploitation of mineral resources shall submit a recovery plan to receive a mining concession. Accordingly, the environmental recovery of the degraded areas caused by mineral exploitation activities shall have been planned since their conception. According to Minas Gerais law, entrepreneurs must also submit to the environmental agency an environmental plan for closing two years before the planned mine closing.

 

On October 1, 2020, the Brazilian federal government issued law No. 14,066 which, among other provisions, amended the Brazilian Mining Code in order to explicitly state that all mine closure plans must be approved by the ANM as well as the environmental licensing agency. We have been complying with legal requirements regarding mine closure plans and continue to comply with all regulatory and environmental requirements.

 

The state of Minas Gerais has also passed legislation on decommissioning plans for industrial activities. The Três Marias unit was the first metal production operation to prepare a decommissioning plan at the licensing stage, including the calculation of a financial provision. In the case of the Aripuanã and Caçapava do Sul greenfield projects, presentation of a decommissioning plan is one of the requirements for obtaining an environmental license.

 

Royalties and other taxes on mining activities

 

Revenues from mining activities are subject to the Compensação Financeira pela Exploração de Recursos Minerais (“CFEM”) which is paid to the ANM. CFEM is a monthly royalty based on the sales value of minerals, net of taxes levied on the respective sale. When the produced minerals are used in its internal industrial processes, CFEM is determined based on the costs incurred to produce them. CFEM is determined by a reference price of the respective mineral to be defined by the ANM. The applicable rate varies according to the mineral product (currently 2.0% for zinc, lead, copper and silver). In addition, we are required to make certain fee payments for exploration authorizations known as the Annual Fee per Hectare (Taxa Anual por Hectare). There is also a monthly inspection fee related to the transfer and commercialization of certain minerals in some Brazilian states, such as Minas Gerais, where the concessions are located.

 

Environmental regulations

 

We are subject to several environmental regulations related to, among other matters, water resources, caves, waste management, contaminated areas, areas of permanent preservation, and conservation of protected areas. Specifically, we have taken the following actions regarding contaminated areas and areas of permanent preservation:

 

92

 

 

Regulatory Matters

 

Contaminated areas. We have carried out environmental assessments on our operation units to verify the existence of contamination in groundwater and soil. The assessments prepared for the Brazilian units identified deviations in soil, groundwater and surface water quality standards. We are committed to improving the management of areas identified as contaminated. For most of the identified deviations, we developed a robust remediation plan in order to comply with all legal requirements. We recorded provisions in our consolidated financial statements in respect of any potential liabilities associated with these deviations from applicable standards. See “Operating and financial review and prospects—Overview—Key factors affecting our business and results of operations—Environmental expenses.” We continue to conduct similar assessments with respect to the Peruvian operating units.

 

Areas of permanent preservation. Permanent Preservation Areas (Áreas de Preservação Permanente, or APP) are areas that, because of their importance for preserving water resources, geological stability, biodiversity protection and erosion control, receive special legal protection. The existence of such protected areas within a property, whether in urban or rural locations, may cause restrictions to the performance of the intended activities. Interference or removal of APP vegetation is only allowed in cases of public utility (such as mining activities), social interest or low environmental impact, if there is a prior authorization from the applicable environmental authorities. Most of our properties in the state of Minas Gerais interfere in APPs in some way. For such properties, we have either already established an advanced ongoing regularization process or have started the process for other properties. The regularization process includes the implementation of rigid controls over the properties.

 

Environmental licenses

 

The Brazilian Federal Constitution grants federal, state and municipal governments the authority to issue environmental protection laws and to publish regulations based on those laws. While the Brazilian federal government has authority to issue environmental regulations setting general standards for environmental protection, state governments have the authority to issue stricter environmental regulations. Municipal governments may only issue regulations regarding matters of local interest or as a supplement to federal or state laws.

 

Under Brazilian law, the construction, installation, expansion and operation of any establishment or activity that uses environmental resources, or is deemed to be actually or potentially polluting, as well as those capable of causing any kind of environmental degradation, is subject to a prior licensing process.

 

Notably, in addition to the general guidelines set by the Brazilian federal government, each state is legally competent to promulgate specific regulations governing environmental licensing procedures under its jurisdiction. Depending on the level of environmental impact caused by the exploration/exploitation activities, the procedures for obtaining an environmental license may require assessment of the environmental impact and public hearings, which may considerably increase the complexity and duration of the licensing process and expose the exploration/exploitation activities to potential legal claims.

 

Environmental liability

 

Environmental liability may be determined by civil, administrative and criminal courts, with the application of administrative and criminal sanctions, in addition to the obligation to redress the damages caused. All our operating units have obtained certification under the ISO 14001 standard.

 

Regulation of other activities

 

In addition to mining and environmental regulation, we must abide by regulations related to, among other things, the use of explosives and fuel storage. We are also subject to more general legislation on labor, occupational health and safety, and support of communities near mines, among other matters.

 

Peruvian regulatory framework

 

Mining rights and regulation of mining activities

 

The Natural Resources chapter of the Peruvian Constitution, enacted in 1993, states that mineral resources are the property of the Nation, and the Peruvian State is sovereign in their administration. The Peruvian government may establish by law the conditions for granting exploitation rights and titles to individuals and legal entities.

  

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Regulatory Matters

 

The General Mining Law (Texto Único Ordenado de la Ley General de Minería) is the primary law governing both metallic and non-metallic mining activities in Peru and is complemented by other regulations approved by the MINEM. Under the General Mining Law, mining activities such as exploration, exploitation, mining labor, beneficiation and mining transport (except storage, sampling, prospecting and trade) are carried out exclusively by means of concessions. The Dirección General de Minería (“DGM”) is the regulatory body of the MINEM responsible for proposing and evaluating regulations in the Peruvian mining sector as well as authorizing the commencement of mining activities in Peru.

 

A mining concession allows its holder to carry out exploration and exploitation activities within the area established in the respective concession title, provided that prior to the beginning of any mining activity, such concession title is granted by the Instituto Geológico, Minero y Metalúrgico (“INGEMMET”) and other applicable administrative authorizations are obtained (e.g., mining, environmental, use of water, use of explosives, impact on indigenous communities, etc.). A concession provides its titleholder with the exclusive right to undertake mineral exploration and mining activity within a determined area but does not grant the titleholder the right to own the surface land where the concession is located. Therefore, for the holder of a mining concession to develop exploration and/or exploitation works, the latter has to purchase the corresponding surface land from the owners, reach an agreement for its temporary use or obtain the imposition of a legal easement by the MINEM, which is rarely granted. There are special proceedings for purchasing or acquiring temporary rights over barren lands owned by the state.

 

Summary of Peruvian concessions

 

In Peru, we hold, through Nexa Peru and its subsidiaries, 909 mining and exploration concessions, which cover a total area of 411,727.3 hectares and 134 mineral claims totaling 88,213.6 hectares. Of our mines in Peru, the Atacocha mine property includes 147 mining concessions that cover an area of 2,872.51 hectares and one beneficiation concession, the El Porvenir mine property includes 25 mining concessions that cover an area of 4,846.8 hectares and one beneficiation concession, the Cerro Lindo mine has 68 mining concessions that cover an area of 43,750.2 hectares and one beneficiation concession and the inactive Chapi mine property includes 32 mining concessions that cover an area of 4,625.6 hectares and one beneficiation concession. In addition, we have 223 mineral rights concessions for greenfield projects in Peru that cover a total area of 83,886.7 hectares. Our prospective projects include 414 mining concessions that cover an area of 271,745.57 hectares.

 

All our mining and processing concessions in Peru are in good standing. Maintaining our concessions in Peru in good standing involves, among other requirements, (i) paying the annual validity fee and production penalties (when applicable) for mining concessions with no production or with no effective exploration or (ii) paying the annual validity fee and complying with minimum production or investment requirements established in mining law.

 

Failure to pay such validity fees or production penalties (when applicable) for two consecutive years results in the cancellation of the respective mining concessions or benefit concessions granted by the Peruvian government. Our mining and benefit concessions will not expire unless we do not comply in paying these fees or with minimum production or investment as required by law and depending on the applicable regime.

 

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Regulatory Matters

 

The following table summarizes our mining concessions in Peru.

 

       

Concessions 

 
   

Project 

 

Titles 

   

Area (hectares)

 
Mines   Atacocha mine     147       2,872.5  
    El Porvenir mine     25       4,846.8  
    Cerro Lindo mine     68       43,750.2  
    Chapi mine (inactive)     32       4,625.6  
Greenfield Projects   Florida Canyon Zinc     16       12,600.0  
    Chapi Greenfield     14       5,855.6  
    Hilarión     71       15,408.3  
    Magistral     36       16,282.5  
    Pukaqaqa     34       11,131.3  
    Shalipayco     52       22,609.0  
Prospective Projects   Various     414       271,745.6  
Total         909       411,727.3  

 

Exploration and authorization and mining concession regimes

 

Mining concessions are granted for an indefinite term, though dependent on the fulfillment of certain legal obligations. The commencement and re-commencement of exploration and/or exploitation mining activities are subject to the prior obtainment of an authorization for the commencement of activities before the DGM. Such authorizations could be subject to a prior consultation procedure with indigenous communities, carried out by MINEM, if mining activities were to impact their collective rights and territories as determined by the Ministry of Culture.

 

As of December 31, 2020, we primarily owned metallic mining concessions with respect to zinc, copper, silver and lead. Substantially all of Nexa Peru’s concessions were granted prior to 2008. Our mining rights and concessions are in full force and effect under applicable Peruvian laws. We believe that we comply in all material respects with the terms and requirements applicable to our mining rights and concessions.

 

Decommissioning

 

Titleholders of mining exploitation and beneficiation activities, and, in some cases, of exploration activities require the prior approval of a mine closure plan, which includes the environmental rehabilitation, restoration and remediation measures that shall be executed along with the mining operations and until its closure. Once the corresponding mine closure plan is approved, an environmental guarantee must be granted in favor of the MINEM to back up the costs associated with the execution of the mine closure plan. Mining exploitation and beneficiation activities may only be initiated once the mine closure plan is approved and the corresponding environmental guarantee is duly submitted before the competent authority. The corresponding environmental guarantee is submitted yearly. If the titleholder of an ongoing mining operation fails to comply with this obligation, the MINEM is entitled to suspend the execution of such mining operation.

 

Royalties and other taxes on mining activities

 

Holders of mining concessions are required to pay a mining royalty (regalía minera) to the Peruvian government for the exploitation of metallic and non-metallic resources. The amount of the royalty is now payable on a quarterly basis and is equal to the greater of (i) an amount determined in accordance with a statutory scale of marginal tax rates from 1.0% to 12.0% based on a company operating income margin and applied to that company’s operating income and (ii) 1.0% of a company’s sales, in each case during the applicable quarter. We are required to pay annual fees (derecho de vigencia) for our mining concessions and, in some cases, mining production penalties for not reaching the minimum production levels set by Peruvian mining law.

 

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Regulatory Matters

 

Holders of mining concessions are also required to pay a Special Mining Tax (Impuesto Especial a la Minería) to the Peruvian government. The Special Mining Tax is payable on a quarterly basis and is calculated based on the operating income derived exclusively from the sale of metallic resources, with marginal rates between 2.0% and 8.4%.

 

Holders of mining concessions that are subject to administrative legal stability (in force as of the effective date) under an Agreement of Guarantees and Measures for Investment Protection entered into with the MINEM and Mining shall enter into an agreement with the Peruvian government for the payment of a Special Charge on Mining (Gravamen Especial a la Minería, or “GEM”). The GEM is payable on a quarterly basis and is calculated based on the operating income derived exclusively from the sale of metallic resources, with marginal rates between 4.00% and 13.12%.

 

Tax stability agreements

 

On March 26 of 2002, Nexa Peru entered into an Agreement of Guarantees and Measures for Investment Protection with MINEM with respect to our Cerro Lindo unit. Pursuant to section 9 of said Agreement, until December 31 of 2021, certain guarantees will benefit with respect to operations of the Cerro Lindo unit including, among others, free commercialization of the products proceeding from such unit, free disposition of the currencies generated from the export of the products proceeding from such unit, the right to use the global depreciation rate applicable on the fixed assets relating to the Cerro Lindo unit up to 20.0% per year, the right to keep the accounting corresponding to the Cerro Lindo unit in U.S. dollars, and tax stability.

 

Municipal permits

 

The regularization process for Nexa CJM’s administrative offices and construction permits was fully completed on September 22, 2017. The permit for construction of a new locker room at Nexa CJM’s facilities was obtained on December 11, 2019, and the municipal license for the operation of its water catchment plant located in Carapongo was obtained on August 5, 2020. Under the General Mining Law, all Peruvian mines located in rural areas such as Cerro Lindo, Atacocha, El Porvenir and Chapi are exempted from paying municipal taxes and obtaining municipal permits.

 

Environmental regulations

 

The development of economic activities in the Peruvian territory, such as those related to the mining industry, are subject to a broad range of general environmental laws and regulations related to the generation, storage, handling, use, disposal and transportation of hazardous and controlled materials; the emission and discharge of hazardous materials into the ground, air or water; and the protection of migratory birds and endangered and threatened species and plants. These regulations also set environmental quality standards for noise, water, air and soil, which shall be considered for the preparation, assessment and approval of the corresponding environmental management instrument, granted by the National Service for Environmental Certification of Sustainable Investments (“SENACE”).

 

The Ministry of Environment and other administrative entities, such as the Dirección General de Asuntos Ambientales Mineros (“DGAAM”), have the authority to enact regulations related to environmental matters. Additionally, the Environmental Supervision Agency (Organismo de Evaluación y Fiscalización Ambiental, or “OEFA”), is the competent authority in charge of supervising and imposing sanctions on mining companies upon non-compliance of applicable environmental legislation. In addition, there are other competent governmental agencies or authorities on specific environmental matters such as water, forestry resources, protected natural areas and aquatic environment that regulate, authorize and supervise environmental compliance and liability.

 

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Regulatory Matters

 

Environmental permit regularization processes

 

Supreme Decree 040-2014-EM provided special procedures allowing us to acquire environmental and operational permits for mining operations and to regularize the mining of certain areas within the Cerro Lindo and Atacocha mines. It also provided for special procedures to regularize the construction and operation of certain mining components in Nexa CJM’s “Poza de Lodos Neutros” and “Poza No. 5,” which lacked the corresponding mining and environmental permits. With respect to Cerro Lindo, this permit regularization process was fully completed on July 5, 2017. With respect to the Atacocha mine, on December 18, 2017, we completed the permit regularization with respect to the areas that will be exploited. With respect to Nexa CJM’s “Poza de Lodos Neutros” and “Poza No. 5,” the regularization processes have been concluded and, therefore, these components currently have sufficient environmental and mining permits in place. These regularization procedures are independent from any sanctioning administrative procedure that the OEFA may initiate in connection with the construction and operation of mining components without the corresponding environmental permits.

 

Similarly, Supreme Decree 013-2019-EM allowed for further regularization procedures to be carried out as of January 6, 2020, which will also allow us to acquire environmental and operational permits for infrastructure and mining areas in the Cerro Lindo, Atacocha, El Porvenir and Chapi mines. The regularization procedures for all four operations are currently underway.

 

Regulation of other activities

 

In addition to mining and environmental regulation, we must abide by regulations related to, among other activities, the use of explosives, fuel storage, controlled substances, telecommunications, archeological remains and electricity concessions. We are also subject to more general legislation on labor, occupational health and safety, and peasant and indigenous communities, among others.

 

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Overview

 

II. Operating and financial review and prospects

 

Overview

 

Executive summary

 

During 2020, despite macroeconomic headwinds, increased volatility in commodity prices and operational setbacks due to the impact of the COVID-19 pandemic, particularly in the second quarter of the year, we were able to deliver solid operating results with EBITDA growing nearly 16% compared to 2019 and we generated net cash from operating activities of US$292 million during the year, overcoming challenges and restrictions stemming from the COVID-19 pandemic and its macroeconomic effects. These operational challenges are likely to continue in 2021, particularly if the spread of the COVID-19 pandemic is not deterred by ongoing vaccination campaigns and if the anticipated vaccine-propelled recovery does not materialize, which could lead to further restrictive measures being imposed by governments that may further affect macroeconomic conditions, as well as our operations.

 

We believe that the Nexa Way program, which aims to structurally improve our business model and transform our culture, has assisted us in adeptly navigating this unprecedented scenario. The Nexa Way program generated annualized positive impacts to EBITDA in 2020, based on the initiatives implemented in 2019. In light of the COVID-19 pandemic, new Nexa Way initiatives emerged during the second half of 2020 which were implemented at a cost of US$12 million, included in our general and administrative expenses. We expect additional initiatives to be implemented during the first half of 2021. We estimate that these new initiatives could generate additional gains, as well as some additional non-recurring costs.

 

Following the end of government-mandated temporary suspension of our Peruvian mines and limited smelters production, we safely resumed our activities during the second half of 2020 and we are currently running at normal levels. In Brazil, we operated our mines at higher throughput that allowed us to partially compensate the Peruvian reduced volumes. For more information on the impact of the COVID-19 pandemic on Nexa’s operations, see “Risk Factors—Global or regional health considerations, including the outbreak of a pandemic or contagious disease, such as the ongoing COVID-19 pandemic, have had and could continue to have adverse effects on our business, financial condition and results of operations” and the “—COVID-19” section below.

 

In response to the COVID-19 pandemic, we proactively managed our liquidity position by assuming additional debt during the first half of the year, adding approximately US$300 million to our cash balance through export credit notes issued in March and April, and the issuance of a US$500 million 7-year bond in June, with the net proceeds being used to repay certain existing financial indebtedness.

 

Our main development project, Aripuanã, is progressing according to the updated project schedule and we are on track to begin production in early 2022. This project is aligned with our objectives to increase integration between our mining and smelting operations and to reduce third-party zinc concentrate supply needs.

 

In response to our commitment to capital discipline to navigate this uncertain scenario, we temporarily suspended exploration activities during the second quarter of 2020. Exploration activities resumed in the third quarter and we have maintained our revised project portfolio and timeline following our aim to replace and increase mineral reserves and resources, subject to additional COVID-19-related measures.

 

In terms of our brownfield projects, in 2020 the Vazante mine-deepening project progressed as planned and the investment amounted to US$13 million. In 2021, we plan to complete the excavation of phase 2 of the EB-140, which is the main stage of the mine deepening project and its final assembly is estimated to be concluded by 2022.

 

During the second half of 2020, exploration activities at the Bonsucesso project were resumed as planned and engineering studies have resumed in the first quarter of 2021. Bonsucesso is expected to extend the life of mine of Morro Agudo and use the existing mine facilities of the complex, reinforcing the integration of our mines and smelters in Brazil. Magistral engineering studies continue to progress and we expect to advance further detailed engineering and optimization opportunities to mitigate the risk of project execution, before consideration of project’s approval. In the fourth quarter, we also restarted exploration activities at the Hilarión project. In addition, the pre-feasibility studies at Shalipayco, Pukaqaqa and Florida Canyon remain on hold.

 

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Overview

 

Our 2020 financial results were impacted by factors including: (i) lower overall metal prices and lower volumes, (ii) the decrease in costs and exploration and project evaluation expenses and (iii) the depreciation of the Brazilian real against the U.S. dollar. In addition, our 2020 results were impacted by the recognition of a US$557 million non-cash impairment comprised of (i) an impairment loss of US$226 million in Cerro Pasco cash-generating unit (“CGU”), (ii) an impairment loss of US$267 million in goodwill in Mining Peru (Mining Peru is the lowest level within Nexa at which the goodwill generated in the acquisition of Nexa Peru is monitored) and (iii) individual assets impairment in the amount of US$45 million in the Jarosite conversion project, US$10 million in relation to the Ambrosia mining assets and US$10 million in relation to Atacocha underground assets. For further information, please refer to Note 33 of our consolidated financial statements.

 

In 2020, we had an 18% decrease in our mine production (zinc equivalent), from 609.4 thousand tonnes in 2019 to 498.3 thousand tonnes in 2020, mainly driven by the decrease in processed ore volumes in our Peruvian mines, which were affected by the government-mandated temporary shutdowns in response to the COVID-19 pandemic. Our total zinc metal (metallic zinc and zinc oxide) sales decreased by 5.8% in our smelting operations, from 621.2 thousand tonnes in 2019 to 585.4 thousand tonnes in 2020.

 

In 2020, our net revenues were 16.4% lower compared to 2019, reaching US$1,950.9 million, primarily impacted by lower average LME prices of zinc and lead compared to the 2019 average and lower volumes due to the impact of COVID-19. In 2020, we had a net loss of US$652.5 and Adjusted EBITDA of US$402.9 million, a 15% increase compared to 2019, primarily as a result of (i) lower mining and smelting costs, (ii) the decrease in mineral exploration and project evaluation expenses and (iii) the positive effect of the appreciation of the U.S. dollar against the Brazilian real; which offset COVID-19 related costs, lower LME prices and the decrease in volume. See “Selected Financial Data— Non IFRS measures and reconciliation” for reconciliations of Adjusted EBITDA to net (loss) income.

 

Our capital expenditures totaled US$336.5 million in 2020, an 18% decrease compared to 2019, mainly due to effects of the COVID-19 pandemic and our decision to reduce exploration projects and maintain only essential investments (non-expansion), with the exception of Aripuanã. In 2020, 66% of our capital expenditures related to the construction of Aripuanã (US$187 million), as well as the Vazante mine deepening project (US$13 million), which aims to extend the life of mine by seven years.

 

Outlook

 

In 2021, we estimate that we will produce (i) between 322.0 thousand tonnes and 353.0 thousand tonnes of zinc contained in concentrate, (ii) between 26.0 thousand tonnes and 30.0 thousand tonnes of copper contained in concentrate, (iii) between 42.0 thousand tonnes and 49.0 thousand tonnes of lead contained in concentrate and (iv) between 8,531 thousand ounces to 9,317 thousand ounces of silver contained in concentrate. These estimates assume, among other things: (i) Peruvian and Brazilian mines operating at normal utilization rates, (ii) the continued suspension of the Atacocha underground mine for an indefinite period of time, (iii) our assets continue to operate subject to additional measures and safeguard protocols to mitigate the spread of COVID-19.

 

In 2021, we expect to sell between 580.0 thousand tonnes and 596.0 thousand tonnes of metallic zinc product volume and between 35.0 thousand tonnes and 39.0 thousand tonnes of zinc oxide product volume. These estimates assume, among other things, an increase in performance through regular production across our smelters with productivity gains driven by: (i) smelters continuing to operate at higher utilization rates; and (ii) our assets continuing to operate subject to additional measures and safeguard protocols to mitigate the spread of COVID-19.

 

Over the next three years, we are expecting zinc equivalent metal production to increase 6.1% on average (based on the midpoint of the guidance range from 2021 to 2023), mostly driven by the start-up of the Aripuanã project in 2022. We expect to produce, in terms of zinc equivalent, between 518.0 and 578.0 thousand tonnes in 2021, 545.0 and 637.0 thousand tonnes in 2022 and 538.0 to 625.0 thousand tonnes in 2023. For the forecasted period, zinc head grade is expected to be in the range of 2.71% and 2.97%, copper head grade is expected to be in the range of 0.27% and 0.37% and lead head grade is expected to be in the range of 0.46% and 0.60%.

 

Metal sales volume at the midpoint of the guidance range (615.0 to 635.0 thousand tonnes) in 2021 is estimated to increase 40.0 thousand tonnes compared to 2020. For 2022, metal sales volume is forecasted to increase 2.5 thousand tonnes over 2021 (ranging from 615.0 to 640.0 thousand tonnes), and remain stable in 2023 (ranging from 615.0 to 640.0 thousand tonnes). The estimated increase in performance is explained by the fact that our smelters should continue to benefit from improved operational performance and to run at normal utilization rates after the temporary reduction in production due to COVID-19 related measures.

 

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Overview

 

We also provided our cash cost net of by-product credits estimates for 2021. For our mining segment, we estimated cash cost after by-product credits at US$0.33 per pound of zinc sold mainly driven by lower benchmark treatment charges and increased production volumes, which should offset the normalization of mine development and infrastructure costs in Peru after the temporary shutdown restrictions, as cost reduction initiatives also remain in place. On the other hand, smelting cash cost after by-product credit is estimated at US$0.95 per pound of zinc sold, an increase of 18.7% compared to 2020 driven by (i) lower benchmark treatment charges, (ii) higher LME prices and (iii) increased raw material costs compared to 2020; which should be partially offset by cost reduction initiatives.

 

Our estimated capital expenditures for 2021 is US$450 million and includes the estimated US$232 million investment in the Aripuanã project. In response to COVID-19, in 2020 we focused our efforts on preserving cash. Consequently, we temporarily reduced non-expansion investments, maintaining all the essential investments to operate safely. In 2021, we expect to resume our sustaining and HSE investments, similar to pre-pandemic levels, in order to continue building a sustainable long-term business. In 2021, we also expect to incur approximately US$71.0 million in mineral exploration and project evaluation expenses, with US$51.0 million allocated to mineral exploration (including brownfields, greenfields, mining properties and administrative issues) and US$20.0 million allocated to project evaluation. In mineral exploration, we plan to continue our efforts to replace and increase mineral reserves and resources.

 

These estimates should be considered preliminary, subject to change and are based on several assumptions that management believes to be reasonable as of the date of this report, which are subject to change based on internal and external developments. As of the date of this report, we continue to monitor developments related to the COVID-19 pandemic, the community protest at the Atacocha property, which have led to the temporary suspension of the operations of its San Gerardo open pit mine and the temporary suspension of the underground Extremo Norte mine in Vazante due to operational issues. We cannot predict how and to what extent the pandemic, the protest activities or other operational issues may impact our current plans and objectives for 2021, including with respect to our consolidated production guidance and our current capital expenditure, mineral exploration and project evaluation disbursements. See “Forward-looking statements.” For cash cost guidance, see “Presentation of financial and other information—Non-IFRS measures.”

 

Key factors affecting our business and results of operations

 

Reporting segments

 

We have two reportable segments: mining and smelting. A major part of our zinc mining production, representing approximately 99.0% of production in 2020, is processed in our own smelters. Similarly, a major part of the zinc raw material consumption for our smelting operations, representing approximately 53.6% of concentrates in 2020, comes from our own mines. As a result, the revenues of our mining segment include sales to the smelting segment, and the costs of our smelting segment include purchases from the mining segment. We calculate internal transfer prices from our mines to the smelters on an arm’s length basis to evaluate the performance of our mining and smelting segments individually. These revenues and costs are eliminated in our consolidated financial statements.

 

The profitability of our mining segment depends primarily on world prices of the metals we produce, and on our costs to produce concentrates. It is also affected by treatment charges, which are amounts representing the cost of further processing that are applied to reduce the price of concentrate. Other factors affecting pricing are discussed below.

 

The profitability of our smelting segment does not depend directly on market prices for metals because they have a similar impact on our revenues and our costs. It is affected primarily by treatment charges (which reduce our costs to acquire concentrates), by the premium over the market price of metals that we can charge for our products, and by the operating costs of our smelters and their efficiency in recovering the metal content of the concentrates we purchase.

 

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Overview

 

Segments are reported in accordance with IFRS 8 “Operating Segments,” and the information is presented to the chief executive officer, who is the chief operating decision maker in accordance with IFRS 8. Segment results are derived from the accounting records and are adjusted for reallocations between segments, impairment of non-current assets and other miscellaneous adjustments, if any, and transfer pricing adjustments. See Note 2 to our consolidated financial statements.

 

Metal prices

 

Our financial performance is significantly affected by the market prices of zinc, copper and lead, and, to a lesser extent, silver, gold and the other by-products of our smelting operations. Metal prices have historically been subject to wide fluctuations and are affected by numerous factors beyond our control, including the impact such factors have on industries representing first-uses and end-uses of our products. These factors, which affect each metal to varying degrees, include international economic and political conditions, levels of supply and demand, the availability and cost of substitutes, inventory levels maintained by producers and others and, to a lesser degree, inventory carrying costs and currency exchange rates. In addition, market prices have on occasion been subject to rapid short-term changes due to speculative activities.

 

The market prices for zinc, copper and lead are typically quoted as the daily cash seller and settlement price established by the LME. LME zinc prices are influenced by global supply and demand for metallic zinc and zinc oxide. The supply of metallic zinc and zinc oxide depends on the amount of zinc concentrates and secondary feed materials produced and the availability of smelting capacity to convert them into refined metal. This also applies to copper and lead.

 

The table below sets forth the average published market prices for the metals and periods indicated:

 

    For the Year Ended December 31,  
    2020     2019     2018  
    (US$/tonne)     (US¢/lb )     (US$/tonne)     (US¢/lb)     (US$/tonne)     (US¢/lb)  
Average Market                                    
Prices of Base Metals                                    
Zinc (LME)     2,267.00       103.83       2,546.34       115.50       2,921.95       132.54  
Copper (LME)     6,180.63       280.35       5,999.73       272.14       6,523.04       295.88  
Lead (LME)     1,825.58       82.81       1,999.68       90.70       2,242.43       101.71  

 

    For the Year Ended December 31,  
    2020     2019     2018  
                   
Average Market Prices of Precious Metals   (in US$/oz)  
Silver (LBMA)     20.55       16.21       15.71  
Gold (Fix)     1,769.59       1,392.60       1,268.49  

 

The key drivers and recent trends of each of the metals that we produce are discussed below.

 

Zinc

 

Zinc is a major material for the construction and transport industries, which represent approximately 50% and 21% of the zinc end-use, respectively, according to Wood Mackenzie.

 

The annual average price of zinc on the LME as of December 31, 2020, was 11.0% lower when compared to the corresponding period in 2019. During 2020 and according to LME data, zinc stocks remained low, reaching their lowest level on February 4, 2020 and approximately 1% below the closing inventory registered on November 11, 2019. At the beginning of 2020, zinc prices presented a downward pressure significantly impacted by the COVID-19 pandemic and its effects on the global economy. By the second half of the year prices started to recover, mostly linked to an improvement in Chinese demand, the devaluation of the U.S. dollar and issues related to concentrate availability, which also impacted spot treatment charges levels throughout the year.

 

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Overview

 

Spot treatment charges for imported concentrates in China decreased from US$310 per tonne in January 2020 to US$85 per tonne in December 2020, as reported by Wood Mackenzie, while long-term treatment charges increased from US$241 per tonne in 2019 to US$300 per tonne in 2020, as reported by Wood Mackenzie. According to Wood Mackenzie’s December 2020 report, the different movements of spot treatment charges resulted from a tighter concentrate market that followed temporary mine stoppages due to the COVID-19 pandemic, which led to a deficit of 218 thousand tonnes at the close of 2020.

 

In 2020, the zinc metal market closed with a surplus of 461.0 thousand tonnes resulting from a metal production of 13.6 million tonnes (1.5% higher than 2019) and consumption of 13.1 million tonnes (5.5% lower than 2019), according to Wood Mackenzie’s December 2020 report.

 

Refined zinc supply presented an increase as a result of the return of Chinese players that had had their operations suspended due to enforcement of new environmental regulations. China also contributed to an increase in demand, which was 7.0 million tonnes, or 1%, higher compared to 2019. As of March 16, 2021, refined zinc stock levels increased, reaching 266.4 thousand tonnes at the LME, compared with 202.2 thousand tonnes on December 31, 2020.

 

Copper

 

Copper is used for building construction, power generation and transmission, electronic product manufacturing and the production of industrial machinery and transportation vehicles. The annual average price of copper on the LME as of December 31, 2020 was 3.0% higher than in the corresponding period in 2019. Copper prices decreased 25.1% on January 2, 2020 and reached the lowest price of the year on March 23, 2020, US$4,618 per tonne, resulting from the negative impact of the COVID-19 pandemic. However, copper price recovered over the remainder of 2020 due to an improvement in the macroeconomic conditions combined with a tight metal stock. According to LME data, copper stocks finished the year at 108.0 thousand tonnes, compared to 145.7 thousand tonnes in the December 31, 2019. Total mine production, as well as global demand for refined copper, decreased in 2020 compared to 2019, while refined production increased during the same period, according to Wood Mackenzie.

 

Lead

 

Lead is used in batteries as energy storage and in other products such as ammunition, oxides in glass and ceramics, casting metals and sheet lead. The annual average price of lead on the LME as of December 31, 2020 was 8.7% lower than in the corresponding period in 2019. This decrease reflects the reduction in demand due to the impacts of the COVID-19 pandemic.

 

Silver

 

Silver is considered a precious metal and generally seen as a store of value, so its price tends to be resilient in times of economic uncertainty. In addition, applications in electronics and solar cells have added to the already broad range of uses of silver in currency, jewelry and silverware. The annual average LBMA silver price for the year ended December 31, 2020 was 26.8% higher than in the corresponding period in 2019. This was mainly due to increased demand for commodities that are perceived to be stable investments in a volatile economic scenario, such as silver. During the year, prices increased by 47.8%, from US$17.93 per ounce on January 2, 2020, the first day of trading, to US$26.49 per ounce on December 31, 2020, the last day of trading.

 

Production volumes, ore grade and metal mix

 

Our production volumes, the ore grade from our mines and the mix of metals in our product portfolio affect our business performance. For more details, see “Information on the Company—Mining operations.” Our zinc, copper and lead contained in concentrates production decreased by 13%, 26%, and 26%, respectively, in 2020, mainly due to lower ore treated. Production of silver contained in concentrates decreased by 23.3% in 2020. 

 

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Overview

 

Commercial terms

 

We sell our concentrates and metallic zinc and zinc oxide products mostly through supply contracts with terms between one and four years, and only a small portion is sold on the spot market. The agreements with our customers include customary international commercial terms, such as cost, insurance and freight, or CIF; free on board, or FOB; free carrier, or FCA; and cost and freight, or CFR; pursuant to Incoterms 2010/2020, as published by the International Chamber of Commerce. For concentrates, revenues are recorded at provisional prices and, typically, an adjustment is then made after delivery, based on the pricing terms provided for under the relevant contract.

 

Sales prices for our products are based on LME and/or LBMA quotations. Concentrates are typically sold at the LME price reference minus a discount (treatment charge for zinc and lead; treatment charge and refining charge for copper). Metallic zinc and zinc oxide are typically sold at the LME quotation averaged during a quotation period, such as the month after shipment, the month prior to shipment or another agreed period, plus a negotiable premium that varies based on quality, shape, origin, and delivery terms and also according to the market where metal will be sold. In 2020, 52.0% of the total zinc raw material consumption in our smelters was produced by our mines and 48.0% was purchased from third parties or was obtained from secondary raw materials (including oxide). We buy zinc concentrates from different suppliers in the market to meet our raw material requirements. We sell all our copper and lead concentrates production to metal producers and international traders, on international market terms.

 

Our sales of metallic zinc are highly diversified. Our customer base is composed mainly of end users. Our products reach the following end use industries: transport, construction, infrastructure, consumer goods and industrial machinery. In 2020, 80.3% of our total sales were to customers in the continuous galvanizing, general galvanizing, die casting, transformers and alloy segments and 19.7% were to international traders. Our ten largest customers represented approximately 41.9% of our total sales volume in 2020. In 2020, we sold to more than 350 customers across 43 different countries.

 

Free zinc, treatment charges, premiums and smelter by-products

 

Smelters are processing businesses that achieve a margin on the concentrates and other feedstocks they process; in large part, the price for the underlying metal is effectively passed through from the miner supplying the concentrate, or the supplier of the secondary feed material, to the smelter’s customer. Our smelters use zinc concentrate as feedstock, which is supplied from our mines and from third-party suppliers. The smelter earns revenue from (i) the treatment charge reflected as a discount in the purchase price it pays, (ii) the refined metal it can produce and sell over and above the metal content it has paid for in concentrates purchased from the miner (free metal) and (iii) any premium it can earn on the refined products it sells to its customers. By-products can also contribute to a smelter’s revenue. By-products from our smelting operations include, among others, silver, gold, copper, cement, sulfuric acid, lead concentrate, lead-silver concentrate, silver concentrates, limestone and copper sulfate.

 

Free zinc and treatment charges

 

Free zinc is the difference between the amount of zinc that is paid for in the concentrates and the total zinc recovered for sale by the smelter. The value of the zinc that is paid for corresponds to 85.0% of zinc content, which has historically been the industry standard, multiplied by the LME price of zinc. The zinc content which is not paid for is considered “free zinc.” The margin of a zinc smelter improves as the amount of metal in zinc concentrates that it can recover increases.

 

The treatment charge (“TC”) is a discount per tonne of concentrates, which is determined by negotiation between the seller (a mine or a trading company) and the buyer (a smelter). Treatment charges can be benchmark TC (negotiated by the major miners and buyers), spot or negotiated.

 

We apply a Benchmark TC for our integrated mining and smelter operations in Peru. For our other purchases of zinc concentrate from third-party miners and trading companies, the treatment charge is based on the Benchmark TC, spot treatment charges or treatment charges negotiated annually with miners or trading companies.

 

In order to reduce volatility, for the majority of our third-party contracts, which are renewed throughout different periods during the year, we consider the 3-years average TC. The reference (average benchmark TC of 2020, 2019 and 2018) for 2020 stood at USD 230.6/t concentrate, up 23% from the previous reference (average benchmark TC of 2019, 2018 and 2017).

 

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Overview

 

The market trend for treatment charges reflects the supply and demand for concentrates in the market. Treatment charges tend to fall when demand increases relative to supply, and they tend to rise when demand falls. In other words, when there is an excess of concentrate compared to the smelting processing capacity, treatment charges tend to rise and when there is a deficit of concentrate in the market, treatment charges tend to fall. For information regarding our actual treatment charges, see “Information on the Company—Smelting operations.”

 

The following table sets forth, for the periods indicated, the zinc realized Benchmark TC, expressed in dollars per dry metric tonne (“dmt”) of concentrate.

 

    For the Year Ended December 31,  
    2020     2019     2018  
Treatment Charge (in US$/dmt)     300       236       147  

 

 

Source: Wood Mackenzie.

 

Premiums

 

Like other smelters, we sell metallic zinc and zinc oxide products at a premium over the base LME price. The premium reflects a combination of factors, including the service provided by the smelter in delivering zinc or lead of a certain size, shape or quality specified by its customers and transportation costs, as well as the conditions of supply and demand prevailing in the regional or local market where the metal is sold.

 

Premiums tend to vary from region to region, as transportation costs and the value attributable to customer specifications tend to be influenced by regional or local customs rather than being a function of global market dynamics.

 

The following table sets forth, for the periods indicated, information on premiums for the markets indicated, expressed in U.S. dollars per tonne.

 

   

For the Year Ended December 31,

 
   

2020

   

2019

   

2018

 
Rotterdam (in US$/tonne)     98       116       125  
Singapore (in US$/tonne)     103       125       131  
United States (in US$/tonne)     180       191       187  

 

 

Source: Wood Mackenzie.

 

The following table sets forth, for the periods indicated, the gross premium over the base LME price for zinc oxide realized by our smelting operations in Brazil, expressed in dollars per tonne.

 

    For the Year Ended December 31,  
    2020     2019     2018  
Brazilian operations (in US$/tonne)     482       497       494  

 

Smelter by-products

 

The quantity of by-products produced in our smelters depends on several factors, including the chemical composition of the concentrate and the recovery rates achieved. Concentrates from some mines contain higher levels of by-product metals than concentrates from other mines. In addition, the higher rate of by-product recovery, increase the number of by-products that can be produced and sold.

 

Sulfuric acid is the principal by-product we sell. It is manufactured from the sulfur dioxide gas generated from roasting zinc concentrates. While the zinc smelters use sulfuric acid in their leach plants, almost all this requirement is generated in each zinc smelter’s electrolysis plant, and only small amounts of the sulfuric acid produced are used in its facilities, leaving the rest available for sale. We sell sulfuric acid under annual or multi-year contracts and spot sales.

 

104

 

 

Overview

 

Silver concentrate is another relevant by-product that we produce at our Cajamarquilla and Juiz de Fora smelters. Silver concentrate is one of the components of zinc concentrate and is obtained during the zinc metallurgical flotation process. Recovered silver is sold primarily to international traders and local customers.

 

Operating costs and expenses

 

Our ability to manage our operating costs and expenses is a significant driver of our business performance. We focus on controlling and limiting our costs and expenses so that we are better prepared to overcome less favorable pricing conditions.

 

Energy costs

 

Our total cost of energy is composed of the operating costs of our own hydroelectric power plants, long-term electricity supply contracts, transmission and distribution charges and fees.

 

In Peru, the energy market is more stable in terms of generation (hydrology forecast) and prices. We obtain 2.5% of the electricity for our operations from our own hydroelectric power plants and 97.5% from third parties with contracts with terms ranging from one to two years.

 

In Brazil, the electricity for our operations comes from five hydroelectric plants in which our subsidiary Pollarix has directly or indirectly the following interests as of December 31, 2020: a 21.0% participation in the consortium Enercan (Campos Novos hydroelectric power plant), 100.0% ownership of a hydroelectric power plant (Picada) located in Minas Gerais, a 12.6% participation in the consortium Amador Aguiar I, a 12.6% participation in the consortium Amador Aguiar II and a 23.9% participation in the consortium Igarapava. We account for the consortiums as joint operations, as discussed in Note 4(b) to our consolidated financial statements. On a consolidated basis, our costs for electricity in Brazil reflect the operating costs of the hydroelectric facilities and are sensitive to a variety of factors, including hydrologic variables.

 

The only activity of Pollarix is to own our energy assets, and it sells energy to our Brazilian operating subsidiaries at market prices. We own all the common shares of Pollarix, which represents 33.33% of its total share capital and/or its affiliates. The remaining shares are preferred shares with limited voting rights, which are owned by our major shareholder VSA. Under the terms of the preferred shares, VSA is entitled to dividends per share equal to 1.25 times the dividends per share payable on the common shares. See “Information on the Company—Other operations—Power and energy supply—Brazil.” As a result, a substantial part of the profits recognized by Pollarix from selling energy to our Brazilian operating subsidiaries will represent non-controlling interest in our income statement.

 

Environmental expenses

 

Our mines and smelters operate under licenses issued by governmental authorities that control, among other things, air emissions and water discharges and are subject to stringent laws and regulations relating to waste materials and various other environmental matters. Additionally, each operation, when it ultimately ceases operations permanently, will need to be rehabilitated.

 

We have made significant investments to reduce our environmental impact in the areas in which we operate and to ensure that we are able to comply with environmental standards. All our operational units have environmental improvement initiatives relating to reducing emissions and waste and improving the efficiency of use of natural resources and energy.

 

Where appropriate, we establish environmental provisions for restoration or remediation of existing contamination and disturbance, with all material issues being reviewed annually. Provisions associated with smelter and mining operations sites primarily relate to soil and groundwater contamination.

 

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Overview

 

Since 2016, we have conducted an extensive study and update of our decommissioning plans, including potential environmental obligations. During this period, we also modified our internal policies for decommissioning and environmental issues, which require frequent updates of environmental studies to reflect the best international practices. As a result of these adjustments, we recorded additional environmental provisions of US$3.9 million and US$3.1 million in 2019 and 2020, respectively. Although not expected in the near future, changes in legislation and adjustments to our internal policies after the ongoing evaluations could require additional provisions.

 

COVID-19

 

During 2020, COVID-19 spread across the world with severe effects that have impacted the global economy in general and our business and operations. As a response to COVID-19, we implemented and continue to implement additional safety procedures in all our operations to ensure the health and safety of our employees, contractors and communities.

 

In 2020, we created a Crisis Committee, which includes all executive officers, certain key general managers and personnel to carry out preventive safety and health procedures in our operations and offices. We have implemented several measures to help protect our employees, contractors and local communities and we are working on three main fronts: (1) health, safety and people, (2) business continuity and (3) stakeholders. We have also implemented business continuity measures to mitigate and reduce any impacts of the global pandemic on our operations, supply chain and financial situation and remain committed to these efforts, particularly considering the recent “second wave” spread of the virus around the world.

 

In 2020, government authorities in the countries in which we operate, and in particular in Peru, implemented policies in response to the COVID-19 global pandemic, which negatively affected our financial position, results of operations and cash flows for the year ended on December 31, 2020, mainly during the second quarter of 2020. In this context, in Peru, on March 15, 2020, the government declared a state of emergency in response to COVID-19, imposing operating restrictions on non-essential industries, which included the mining sector. Consequently, mining operations at Cerro Lindo, Atacocha and El Porvenir were suspended and the operation of the Cajamarquilla smelter was reduced to approximately 50% of its production capacity. The quarantine period was initially expected to last until the end of March but was subsequently extended until early May 2020. During this period, mining activities were limited to critical operations with a minimum workforce to ensure appropriate maintenance, safety and security.

 

On May 6, 2020 the Peruvian government announced the conditions for the resumption of operations for different sectors, including mining operations above 5ktpd. Cerro Lindo and El Porvenir mines restarted operations on May 11, 2020, following the end of the state of emergency and gradually ramped up until the third quarter of 2020. The Cajamarquilla smelter also gradually improved its operating rate from mid-May to July 2020.

 

Following the supreme decree published by the Peruvian government that allowed medium-sized mines to restart operations, on June 8, 2020 we announced the resumption of operations at the San Gerardo open pit mine at the Atacocha site. The Atacocha site includes two mines: the Atacocha underground mine and the San Gerardo open pit mine. As a result of COVID-19 and its impact on the macroeconomic environment, and given our efforts to reduce costs and improve operational efficiency, in June 2020 we decided that the higher-cost Atacocha underground mine would remain suspended and it was placed under care and maintenance. Currently, we have still not defined how long the underground mine’s suspension will last, and the decision will depend on an improvement in the mine’s economic viability. Given this uncertainty, we have impaired certain fixed assets exclusively related to Atacocha’s underground operation for a total of US$10 million. See Note 33 to our consolidated financial statements.

 

In Brazil, our mining and smelting operations operated at normal levels throughout the year, except for the Juiz de Fora smelter which operated at 60% of its normal production capacity in May and June, in anticipation of a lower market demand, but has since returned to normal operating levels.

 

Currently, although our Peruvian subsidiaries continue to operate subject to additional measures to control and mitigate the spread of COVID-19, they have returned to their adjusted normal production levels except for the Atacocha underground mine, which continues to be suspended as mentioned above. On January 27, 2021 the Peruvian government, among other measures in response to the COVID-19 “second-wave,” declared a new lockdown in certain areas of the country for a two-week period which was extended through the end of February 2021. Currently, our Peruvian operations have not been impacted by these additional measures.

 

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Overview

 

Construction activities at the Aripuanã project continue to progress and production is scheduled to start in the beginning of 2022. In October 2020, the original project timeline was extended, and the original capital expenditures estimates were revised upward following a comprehensive study of internal issues and external factors, including COVID-19.

 

In 2020, COVID-19 related costs amounted to US$15 million. COVID-19 related costs are included in the cost of sales and operating expenses. Subject to the duration and extent of COVID-19, we expect these costs to be recurring in our operations in 2021, which are reflected in our cash cost guidance.

 

Although our operations have returned to normal, the ultimate impact of the COVID-19 global pandemic on our financial condition, results of operations and cash flows depends on the continuing duration and severity of the pandemic, on global and local efforts to contain its spread, on the abilities of countries to access and distribute effective vaccines and on the impact of response measures taken by the Company, governments and others. A new period of disruption or an extended global recession caused by the pandemic could materially and adversely impact our results of operations, access to sources of liquidity and overall financial condition. See “Risk Factors—Global or regional health considerations, including the outbreak of a pandemic or contagious disease, such as the ongoing COVID-19 pandemic, have had and could continue to have adverse effects on our business, financial condition and results of operations.”

 

Macroeconomic conditions of the countries and regions where we operate

 

Peru

 

The following table sets forth Peruvian inflation rates, interest rates and exchange rates for the dates and periods indicated.

 

    For the Year
Ended December 31,
 
    2020   2019   2018  
Real GDP growth rate(1)(2)     (11.4)%     2.3%     4.0%  
Internal demand growth rate(2)     (9.8)%     2.4%     4.3%  
Private investment growth rate(2)     (17.2)%     4.0%     4.4%  
Reference interest rate     0.25%     2.25%     2.75%  
CPI rate(2)     1.8%     2.1%     1.3%  
Appreciation (devaluation) of sol against the U.S. dollar     (9.2)%     1.7%     (4.0)%  
Exchange rate of sol to US$1.00 (end of period)(3)     3.6180     3.3120     3.3755  

 

 

Sources: Central Reserve Bank of Perú, Peruvian Ministry of Economy and Finance.

(1) Preview: Bloomberg consensus rate.

(2) Accumulated during each period.

(3) Official offer exchange rates.

 

Brazil

 

The following table sets forth Brazilian inflation rates, interest rates and exchange rates for the dates and periods indicated.

 

    For the Year
Ended December 31,
 
    2020     2019     2018  
Real GDP growth rate (1)(2)     (4.4)%       1.1%       1.1%  
Inflation rate (IGP-M)(2)     23.1%       7.5%       7.5%  
Inflation rate (IPCA)(2)     4.4%       4.3%       3.8%  
CDI rate (end of period)     1.9%       4.4%       6.4%  
SELIC rate (end of period)     2.0%       4.5%       6.5%  
TJLP     4.6%       5.6%       7.0%  
Appreciation (devaluation) of real against the U.S. dollar     (28.9)%       (4.0)%       (17.1)%  
Exchange rate of real to US$1.00 (end of period)(3)     5.1967       4.0307       3.8748  

 

 

Sources: IBGE, the Central Bank, Cetip, and FGV.

(1) Preview published by the Central Bank official report (Focus) as of December 31, 2020.

(2) Accumulated during each period.

(3) Official offer exchange rates.

 

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Overview

 

Effects of exchange rate fluctuations

 

Prices for our products are based on international indices, such as LME prices, and denominated in U.S. dollars. A portion of our production costs, however, is denominated in reais, so there is a mismatch of currencies between our revenue and costs. In 2020, 20.1% of our production costs and operational expenses were denominated in reais. A smaller portion of our costs is denominated in soles since most of our costs in Peru are in U.S. dollars. In 2020, 18.8% of our production costs and operational expenses were denominated in soles. As a result, our results of operations are affected by changes in exchange rates between reais and, to a lesser extent, soles, and the U.S. dollar.

 

In addition, our Brazilian subsidiary Nexa Brazil has substantial intercompany debt to Nexa Resources that is denominated in U.S. dollars. The functional currency of Nexa Brazil is the real, so Nexa Brazil recognizes exchange gains or losses when the value of the real rises or falls against the U.S. dollar. These gains and losses are not eliminated in consolidation because the functional currency of Nexa Resources is the U.S. dollar, so they do not recognize offsetting gains or losses. As of December 31, 2020, the aggregate amount outstanding under these intercompany loans was US$250.7 million.

 

The following table sets forth for the periods indicated (i) the high and low exchange rates, (ii) the average of the exchange rates on the last day of each month for each year and daily for each month and (iii) the exchange rate at the end of each period, expressed in soles per U.S. dollar (sol/US$) and reais per U.S. dollar (real/US$) as reported by the Peruvian Central Bank and the Brazilian Central Bank, respectively.

 

    Exchange Rates of S/ and R$ per US$1.00  
    Period-End     Average(1)       High     Low  
    S/     R$     S/     R$     S/     R$     S/     R$  
Year ended December 31,                                                                
2018     3.3690       3.8748       3.2885       3.6558       3.3900       4.1879       3.2112       3.1391  
2019     3.3140       4.0307       3.3371       3.9461       3.4060       4.2602       3.2832       3.6519  
2020     3.6193       5.1967       3.4984       5,1578       3.6685       5.9372       3.3000       4.0213  
Month                                                                
January 2021     3.6368       5.4749       3.6246       5.3562       3.6459       5.5089       3.6077       5.1626  
February 2021     3.6493       5.5302       3.6451       5.4165       3.6535       5.5302       3.6354       5.3423  
March 2021 (through March 16)     3.7005       5.5848       3.6898       5.6645       3.7101       5.8394       3.6564       5.5637  

 

 

Source: Central Reserve Bank of Peru, Brazilian Central Bank, official offer exchange rates.

(1) Annually, represents the average of the daily exchange rates during the periods presented.

 

Income taxes

 

Income taxes in Luxembourg, Peru and Brazil have a significant impact on our results. Due to economic and political conditions, tax rates in various jurisdictions may be subject to significant changes. Our future effective tax rates could be affected by changes in the mix of earnings in countries with different statutory tax rates, changes in the valuation of deferred tax assets and liabilities and changes in tax laws or their interpretation.

 

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Overview

 

Luxembourg

 

The combined applicable income tax rate (including an unemployment fund contribution) is 24.9% from 2019 onwards.

 

Brazil

 

Our Brazilian subsidiaries are subject to corporate income tax on their Brazilian and non-Brazilian income. In addition to corporate income tax, a social contribution tax is imposed on their worldwide income, and the combined applicable rate is 34.0%.

 

Peru

 

Our Peruvian subsidiaries are subject to Peruvian income tax on their worldwide income and are eligible for a potential credit for foreign taxes paid on income derived from foreign sources. The general income tax rate is 29.5% from 2017 onwards.

 

To promote investments in Peru, investors and Peruvian companies may enter into an agreement with the Peruvian government, a Legal Stability Agreement, to provide a stable legal and tax regime for a specified period. In March 2002, Nexa Peru entered a guarantee and investment protection contract, or the stability agreement. Pursuant to the stability agreement, Nexa Peru can apply a special income tax rate of 20.0% from 2007 through 2021. The 29.5% income tax rate will become applicable to Nexa Peru in 2022. While Nexa Peru remains subject to the stability agreement, it is required to pay the GEM at marginal rates that vary from 4.00% to 13.12% of operating income, depending on the operating margin.

 

Our Peruvian subsidiaries Nexa Resources El Porvenir S.A.C. and Nexa Resources Atacocha S.A.A., do not have stability agreements with the Peruvian government and are therefore subject to a special mining tax (Impuesto Especial a la Minería, or “IEM”), with marginal rates from 2.00% and 8.40% of operating income, depending on the operating margin. In addition, these companies are subject to a mining levy (regalia minera). In 2022, Nexa Peru will become subject to an IEM and mining royalties tax once its tax stability agreement with the Peruvian government expires.

 

Dividends distributed to us by our Peruvian subsidiaries are subject to withholding tax, at a rate of 5.0% for profits earned beginning in 2017 and onwards.

 

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Results of Operations

 

Results of operations

 

The following discussion and analysis of our financial position and results of operations is based on our consolidated financial statements. The following table sets forth our summarized results of operations for the periods indicated.

 

   

For the Year Ended
December 31,

    Variation     % of Net
Revenue from
Products Sold
 
    2020     2019     2018     2020/
2019
    2019/
2018
    2020     2019     2018  
    (in millions of US$)     (percentage)     (percentage)  
Consolidated income statement information:                                                                
Net revenues     1,950.9       2,332.7       2,491.7       (16.4 )     (6.4 )     100.0       100.0       100.0  
Cost of sales     (1,563.9 )     (1,947.8 )     (1,892.2 )     (19.7 )     2.9       (80.2 )     (83.5 )     (75.8 )
Gross profit     387.0       384.9       599.4       0.5       (35.8 )     19.8       16.5       24.2  
Operating expenses:                                                                
Selling, general and administrative     (151.6 )     (216.5 )     (159.6 )     (30.0 )     35.7       (7.8 )     (9.3 )     (6.4 )
Mineral exploration and project evaluation     (57.2 )     (119.1 )     (129.6 )     (52.0 )     (8.1 )     (2.9 )     (5.1 )     (5.1 )
Impairment loss     (557.5 )     (142.1 )     (3.3 )     292.2       4,229.4       (28.6 )     (6.1 )      
Other income and expenses, net     (19.2 )     (18.2 )     27.6       5.3       (166.0 )     (1.0 )     (0.8 )     1.1  
Operating income (loss)     (398.5 )     (111.0 )     334.6       258.9       (133.2 )     (20.4 )     (4.8 )     13.4  
Financial income     11.2       31.1       67.5       (63.9 )     (54.0 )     0.6       1.3       2.7  
Financial expenses     (159.8 )     (117.4 )     (119.1 )     36.1       (1.4 )     (8.2 )     (5.0 )     (4.9 )
Foreign exchange (loss) gain, net     (129.6 )     (18.5 )     (151.0 )     600.2       (87.7 )     (6.6 )     (0.8 )     (6.0 )
Net financial results     (278.2 )     (104.9 )     (202.7 )     165.3       (48.3 )     (14.3 )     (4.5 )     (8.1 )
Share in the results of associates                                                
Income before income tax     (676.7 )     (215.9 )     131.9       213.5       (263.7 )     (34.7 )     (9.3 )     5.3  
Current income tax     (63.2 )     (46.4 )     (71.8 )     36.3       (35.4 )     (3.2 )     (2.0 )     (2.9 )
Deferred income tax     87.3       104.7       33.0       (16.6 )     217.1       4.5       4.5       1.2  
Net (loss) income for the year     (652.6 )     (157.5 )     93.1       314.3       (269.2 )     (33.4 )     (6.8 )     3.7  

 

The following is a discussion of results of operations for 2020, compared to 2019. For a discussion of the financial condition and results of operations for 2019 compared to 2018, please refer to “Operating and financial review and prospects” in our Annual Report on Form 20-F for the year ended December 31, 2019, filed with the SEC on March 20, 2020.

 

Net revenues

 

In 2020, net revenues decreased by 16.4%, or US$381.8 million. This decrease was primarily due to lower zinc and lead prices and lower sales volumes due to the impact of COVID-19. In 2019, net revenues decreased by 6.4%, or US$158.9 million. This decrease was primarily due to lower metal prices.

 

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In 2020, zinc and lead average LME prices decreased by 11.0% and 8.7%, respectively, while copper average LME prices increased by 3.0%. The average LME price of zinc decreased from US$2,546 per tonne in 2019 to US$2,267 per tonne in 2020.

 

The following table shows a breakdown of our net revenues by destination of our sales.

 

    For the Year Ended December 31,  
    2020     2019     2018  
    (in millions of US$)  
Brazil     583.1       625.0       693.4  
Peru     485.9       595.6       674.2  
United States of America     116.7       159.7       141.1  
Luxembourg     76.1       145.5       172.8  
Switzerland     68.9       101.6       126.2  
Singapore     76.7       99.5       37.5  
Korea     77.4       95.9       54.9  
Chile     49.0       80.8       51.2  
Japan     46.7       71.4       93.5  
Argentina     56.2       60.9       90.3  
Austria     35.2       39.9       40.5  
Colombia     34.8       37.1       51.7  
Turkey     25.0       33.9       48.3  
Germany     33.9       20.7       20.9  
China     1.3       9.9       9.5  
Italy     9.9       9.0       5.3  
Others     174.2       145.8       179.8  
Net revenues     1,950.9       2,332.3       2,491.2  

 

The following table sets forth the components of our production and sales volumes for the metals and periods indicated.

 

    For the Year Ended December 31,  
    2020     2019     2018  
Treatment Ore (in tonnes)     10,853,740       13,001,535       13,051,365  
Mining Production—Metal Contained in Concentrate                        
Zinc contained in concentrates (in tonnes)     313,074       361,061       372,793  
Copper contained in concentrates (in tonnes)     28,154       38,184       39,029  
Lead contained in concentrates (in tonnes)     38,009       51,349       52,267  
Silver contained in concentrates (in oz)     6,825,883       8,900,995       7,992,167  
Gold contained in concentrates (in oz)     16,179       24,977       29,224  
External Mining Sales(1)                        
Zinc concentrates (in dry metric tonnes)     0       7,365       15,036  
Copper concentrates (in dry metric tonnes)     109,147       147,608       147,704  
Lead concentrates (in dry metric tonnes)     60,301       98,662       89,831  
External Mining Sales—Metal Contained in Concentrate(2)                        
Zinc contained in concentrates (in tonnes)     0       4,166       7,533  
Copper contained in concentrates (in tonnes)     28,077       38,300       38,932  
Lead contained in concentrates (in tonnes)     33,648       52,472       48,453  
Smelting Production—Zinc Contained in Product Volumes                        
Cajamarquilla (metal available for sale in tonnes)     305,389       340,369       330,766  
Três Marias (metal available for sale in tonnes)     202,764       197,508       207,195  
Juiz de Fora(3) (metal available for sale in tonnes)     79,410       86,155       78,748  
Total zinc metal available for sale production (in tonnes)     587,562       624,032       616,708  

 

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    For the Year Ended December 31,  
    2020     2019     2018  
Zinc Oxide Production—Zinc Contained in Product Volumes                        
Três Marias(4) (Zinc oxide, contained zinc in tonnes)     35,258       38,064       38,565  
Smelting Sales—Product Volumes                        
Metallic zinc (in tonnes)     550,698       584,538       578,144  
Zinc oxide (in tonnes)     34,675       36,689       38,152  
Total smelting sales volumes (in tonnes)     585,373       621,227       616,882  
Smelting Sales—Zinc Contained in Product Volumes(4)                        
Metallic zinc (in tonnes)     549,047       582,627       576,918  
Zinc oxide (in tonnes)     27,740       29,351       30,522  
Total zinc contained in product volumes (in tonnes)     576,786       611,978       607,440  

 

(1) Excluding intercompany sales.
(2) Based on typical zinc contents in metallic zinc products and zinc oxide. For more details, see “Information on the Company—Smelting operations—Zinc contained in smelting products sold.”
(3) Including 2,772 tonnes of zinc ashes and drosses in 2020, 2,538 in 2019 and 2,236 in 2018.
(4) Including 23,256 tonnes of zinc ashes and drosses in 2020, as well as metallic zinc used in the production of zinc oxide in 2020, 27,754 in 2019 and 27,885 in 2018.

 

Cost of sales

 

In 2020, our cost of sales decreased by 19.7%, or US$383.9 million, primarily due to: (i) lower throughput; (ii) lower operating costs in both segments, positively affected by cost reduction initiatives; (iii) lower concentrate prices; and (iv) the average depreciation in the BRL against the U.S. dollar. Abnormal production costs related to the temporary production suspension in response to the COVID-19 pandemic totaled US$74 million.

 

In 2019, our cost of sales increased by 3.0%, or US$55.7 million, primarily due to higher unit costs in our mining segment due to an increase in operating costs (maintenance and third-party services), partially offset by decreased costs in our smelting segment, primarily driven by lower raw material prices and better recovery rates.

 

Selling, general and administrative expenses

 

In 2020, our selling, general and administrative (“SG&A”) expenses decreased by 30.0%, or US$64.9 million, including US$13.7 million non-recurring expenses related to Nexa Way, our operational efficiency initiatives program, which commenced in 2019. This decrease reflects our efforts to reduce costs and a reduction in third-party services.

 

In 2019, our SG&A expenses increased by 35.7%, or US$56.9 million, including US$41.4 million non-recurring expenses related to Nexa Way.

 

Efficiency program – Nexa Way

 

In 2020, in light of the COVID-19 outbreak, new opportunities for operational enhancement emerged. In the second half of 2020, we implemented new initiatives under the Nexa Way program to improve our business and efficiency totaling US$12 million in our SG&A expenses. We estimate additional initiatives to be implemented during the first half of 2021 at an additional non-recurring expense in our SG&A expenses between US$3 to and US$13 million.

 

Mineral exploration and project evaluation

 

In 2020, our mineral exploration and project evaluation expenses decreased by 52.0%, or US$61.9 million, primarily due to our decision to temporarily suspend certain projects to preserve cash in response to the impact of the COVID-19 pandemic. We revised our short-term capital allocation and prioritized certain activities, such as the focus on advanced and brownfield projects. In 2020, our exploration drilling totaled 67.9 km.

 

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Results of Operations

 

In 2019, our mineral exploration and project evaluation expenses decreased by 8.1%, or US$10.5 million, primarily due to reducing our project evaluation expenditures during the second half of 2019 resulting from the postponement of certain greenfield projects, while also continuing to execute our mineral exploration program focused on identifying new ore bodies and upgrading resources classification through infill drilling campaigns. In 2019, our exploration drilling totaled 220.7 km.

 

Impairment loss

 

In 2020, Nexa performed impairment tests as of March and September for all its CGUs: Cerro Lindo, Cerro Pasco, Cajamarquilla, Três Marias, Juiz Fora and Aripuanã. As a result we recognized a non-cash, pre-tax impairment loss on long-lived assets in the total amount of US$557 million, comprised of (i) an impairment loss of US$226 million in Cerro Pasco CGU; (ii) an impairment loss of US$267 million in goodwill in Mining Peru; and (iii) individual assets impairment in the amount of US$45 million in the Jarosite conversion project, US$10 million in relation to the Ambrosia mining assets and US$10 million in relation to Atacocha underground assets.

 

In 2019, Nexa performed an impairment test for all its CGUs: Cerro Lindo, Cerro Pasco, Cajamarquilla, Três Marias and Juiz de Fora. As a result, we recognized an impairment loss of US$142.1 million related to the Cerro Pasco CGU, resulting from the reduction in the mineral reserves and resources estimates that led to a shortening of the life of mine of the CGU. No impairment losses were identified in the other CGUs.

 

For further information, please refer to Note 33 to our consolidated financial statements and independent auditor’s report.

 

Other income and expenses, net

 

In 2020, our other income and expenses, net negatively impacted our results by US$19.2 million, primarily due to an increase in non-cash provisions with respect to legal claims, partially offset by lower mining obligations.

 

In 2019, our other income and expenses, net negatively impacted our results by US$18.2 million, primarily due to an increase in non-cash provisions with respect to labor claims and an inventory write-off in the second quarter, mining obligations; and other operating expenses.

 

The following table sets forth our other income and expenses, net for the periods indicated. See Note 9 to our consolidated financial statements.

 

    For the Year Ended December 31,  
    2020     2019     2018  
    (in millions of US$)  
Other income and expenses, net                        
Tax credits     5.5       4.7       37.6  
Remeasurement of environmental obligations     3.1       2.5       12.1  
Commodities derivative financial instruments     0.9       (0.8 )     17.5  
Loss on sale of property, plant and equipment.     (2.3 )     (0.9 )     (9.9 )
Gain on sale of investments                 0.3  
Contribution to communities     (4.7 )     (5.2 )     (13.4 )
Provision (reversal) for legal claims     (10.9 )     (4.4 )     (3.7 )
Other operating income (expenses), net     (10.9 )     (14.0 )     (12.9 )
Total other income and expenses, net     (19.2 )     (18.2 )     27.6  

 

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Net financial results

 

We recognized a net financial expense of US$278.2 million in 2020 compared to a net financial expense of US$104.9 million in 2019. This increase was mainly due to an increase in foreign exchange loss, higher interest on loans and premium paid on bond repurchase. In 2019, net financial expense was lower than the US$202.7 million recognized in 2018 mainly due to lower net foreign exchange loss of US$12.9 million recognized in 2019 compared to a net foreign exchange loss of US$148.5 million in 2018.

 

Net foreign exchange gains (losses) reflect the accounting effect of the appreciation (depreciation) of the real against the U.S. dollar on certain U.S. dollar-denominated loans made by Nexa Resources to Nexa Brazil (which uses the real as its functional currency). During 2020, the 30.7% average depreciation of the real against the U.S. Dollar resulted in a foreign exchange loss. During 2019, the 7.9% average depreciation of the real against the U.S. dollar also resulted in a foreign exchange loss.

 

Excluding the effect of foreign exchange variation and other financial items, the net financial expense in 2020 increased 72.1% to US$148.6 million compared to US$86.3 million in 2019, driven mainly by an increase in interest on loans and financings and the premium paid on bonds repurchased in 2020. Excluding the effect of foreign exchange variation, the net financial expense in 2019 increased 67.2% to US$86.3 million compared to US$51.6 million in 2018, driven mainly by lower interest income from tax credits.

 

In 2020, our financial income decreased by 64.0%, or US$19.9 million, to US$11.2 million. The decrease in 2020 was due to the lower interest income from financial investments and cash equivalents as a result of the decrease in interest rates, mainly due to the impact of the COVID-19 pandemic. In 2019, our financial income decreased by 53.9%, or US$36.4 million, to US$31.1 million compared to 2018. The decrease in 2019 was due to the US$26.0 million in Brazilian federal tax credits awarded to Nexa Brazil in 2018.

 

In 2020, our financial expenses increased by 36.1%, or US$42.4 million, to US$159.8 million. The increase was due to increased debt on our balance sheet, increased interest on loans and premium paid on bond repurchase. In 2019, our financial expenses decreased by 1.4%, or US$1.7 million, to US$117.4 million from US$119.1 million in 2018 due to an increase in interest on lease liabilities (related to the adoption of IFRS 16) and an increase in interest on other liabilities related to the re-measurement of the ARO.

 

Income before income tax

 

As a result of the factors described above, our loss before income tax was US$676.7 million in 2020, as compared to income before tax of US$215.9 million in 2019.

 

Income tax

 

In 2020, we recorded a net income tax benefit of US$24.2 million. In 2019, we recorded a net income tax expense of US$58.4 million.

 

In 2020, our current income tax expense increased by 36.2%, or US$16.8 million, to US$63.1 million, mainly as a result of the exchange variation impacts. In 2019, our current income tax expense decreased by 35.4%, or US$ 25.4 million, to US$ 46.4 million, mainly as a result (i) foreign exchange tax losses on the payment of intercompany debt between Nexa Brazil and Nexa Resources; and (ii) a decrease in LME prices.

 

The difference between the nominal and effective tax rates in 2020 and 2019 are primarily a result of differences in tax rates from subsidiaries outside Luxembourg, impairment recognized in operations, tax effect of the translation of non-monetary assets of the tax base of NEXA’s Peruvian entities, a temporary special mining levy in Peru and the withholding tax on dividends paid by subsidiaries. In 2020, we recorded a deferred income tax benefit of US$87.3 million, mainly as a result of (i) impairment loss of non-current assets, other than goodwill, which is a permanent difference; (ii) increase through the difference in tax rate of subsidiaries outside Luxembourg; offset by (iii) derecognition of deferred tax assets in the subsidiary Atacocha which in accordance with the Company´s estimates of future taxable income for 2020, these assets will not be recovered. In 2019, we recorded a deferred income tax benefit of US$104.7 million, mainly as a result of (i) foreign exchange losses and (ii) the depreciation and amortization of fair value adjustment to property, plant, equipment and intangible assets. In 2020, we had a nominal tax rate and an effective tax rate of 24.9% and 3.6%, respectively. In 2019, we had a nominal tax rate and an effective tax rate of 24.9% and 27.0%, respectively.

 

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Results of Operations

 

Net (loss) income

 

As a result of the foregoing, we had a net loss of US$652.5 million in 2020 as compared to net income of US$157.5 million in 2019.

 

Results by segment

 

The following table sets forth our summarized results of operations by segment for the periods indicated.

 

 

    For the Year Ended
December 31,
    Variation     Variation  
      2020        2019        2018        2020/
2019 
      2019/
2018 
      2020/
2019 
      2019/
2018 
 
                                                         
      (in millions of US$)      (percentage) 
Consolidated Income Statement Information:            
Net revenues:            
Mining     748.5       1,000.6       1,164.2       (252.1 )     (163.6 )     (25.2 )%     (14.1 )%
Smelting     1,550.3       1,865.7       2,030.6       (315.4 )     (164.9 )     (16.9 )%     (8.1 )%
Intersegments Sales     (375.4 )     (535.8 )     (704.0 )     160.4       168.2       (29.9 )%     (23.9 )%
Adjustments (1)     27.5       2.2       0.9       25.3       1.3       1164.7 %     135.7 %
Total     1,950.9       2,332.7       2,491.7       (381.8 )     (159.0 )     (16.4 )%     (6.4 )%
Cost of sales:                                                        
Mining     (625.4 )     (805.1 )     (711.0 )     179.7       (94.0 )     (22.3 )%     13.2 %
Smelting     (1,287.9 )     (1,655.1 )     (1,878.8 )     367.2       223.7       (22.2 )%     (11.9 )%
Intersegments Sales     375.4       535.8       704.0       (160.4 )     (168.2 )     (29.9 )%     (23.9 )%
Adjustments (1)     (26.0 )     (23.5 )     (6.5 )     (2.5 )     (17.0 )     10.8 %     263.8 %
Total     (1,563.9 )     (1,947.8 )     (1,892.2 )     383.9       (55.6 )     (19.7 )%     2.9 %
Gross profit:                                                        
Mining     123.0       195.5       453.2       (72.5 )     (257.7 )     (37.1 )%     (56.95 )%
Smelting     262.4       210.7       151.8       51.7       58.9       24.5 %     38.8 %
Adjustments (1)     1.5       (21.3 )     (5.5 )     22.8       (15.8 )     (107.0 )%     285.2 %
Total     387.0       384.9       599.4       2.1       (214.5 )     0.5 %     (35.8 )%

 

(1) See Note 2 to our consolidated financial statements.

 

Mining

 

Net revenues

 

In 2020, our net revenues in the mining segment decreased by 25.2%, or US$252.1 million. This decrease was primarily due lower sales volumes from the temporary suspension of our operations in Peru, lower zinc and lead prices and higher benchmark treatment charges. This decrease was partially offset by higher silver and copper prices and record-high annual limestone sales volume in Morro Agudo since we began selling limestone in 2015. In 2019, our net revenues in the mining segment decreased by 14.1%, or US$163.6 million. This decrease was primarily due to lower average metal prices and higher treatment charges compared to the previous year.

 

Our production of zinc contained in concentrates decreased by 13.3% to 313.1 thousand tonnes in 2020, primarily due to the 17% decrease in treated ore volume year-over-year driven by the temporary shutdown of our Peruvian mines, in accordance with measures announced by the Peruvian government in its efforts to control the COVID-19 outbreak. In 2019, our production of zinc contained in concentrates decreased by 3.2% to 361.0 thousand tonnes, primarily due to lower average zinc grade and a slight decrease in treated ore volume. Production was also affected by the temporary reduction in processing capacity in Vazante for the repair of the trunnion used in the concentration plant.

 

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Results of Operations

 

In 2020, our volumes of copper contained in concentrates decreased by 26.3% to 28.2 thousand tonnes of metal contained in concentrates, primarily due to the decrease in treated ore volume explained by the mandatory temporary shutdown of our Peruvian mines, and lower average copper grade. In 2019, our production volumes of copper contained in concentrates decreased by 2.2% to 38.2 thousand tonnes of metal contained in concentrates, primarily due to lower treated ore volume.

 

In 2020, our volumes of lead contained in concentrates decreased by 26.0% to 38.0 thousand tonnes of metal contained in concentrates, primarily as a result of suspension of production in Peru. In 2019, our production volumes of lead contained in concentrates decreased by 1.8% to 51.3 thousand tonnes of metal contained in concentrates, primarily as a result of slightly lower lead grade and the decrease in treated ore volume.

 

In 2020, our external sales volumes of zinc contained in concentrates decreased by 66.7% to 1.4 thousand tonnes of metal contained in concentrates, due to the fact that intercompany volume represented 99% of our sales volume. In 2019, our external sales volumes of zinc contained in concentrates decreased by 44.7% to 4.2 thousand tonnes of metal contained in concentrates, primarily due to higher intercompany volume.

 

Cost of sales

 

In 2020, our cost of sales in our mining segment decreased by 22.3%, or US$179.7 million, mainly due to lower operating costs and volumes, and the depreciation of the Brazilian real against the U.S. dollar. In 2019, our cost of sales in our mining segment increased by 13.2%, or US$94.1 million, mainly due to increased personnel, maintenance, and third-party services costs.

 

Smelting

 

Net revenues

 

In 2020, our net revenues in the smelting segment decreased 16.9%, or US$315.4 million, mainly due to the slowdown in industrial activities in our home markets during the first half of 2020 as a result of the COVID-19 pandemic, as well as lower average zinc prices. In 2019, our net revenues in the smelting segment decreased by 8.1%, or US$164.8 million, mainly due to the decrease in the average zinc metal prices which was partially offset by an increase in sales volume.

 

Our total metal sales were 585.4 thousand tonnes in 2020, 5.8%, or 35.8 thousand tonnes lower compared to 2019.

 

In 2020, our sales volume of zinc metal of 550.7 thousand tonnes decreased 33.8 thousand tonnes versus 2019, driven mainly by pandemic scenario.

 

In 2020, our sales volumes of zinc oxide decreased by 6.0%, or 2.0 thousand tonnes, to 34.7 thousand tonnes. In 2019, our sales volumes of zinc oxide decreased by 3.8%, or 1.5 thousand tonnes, to 36.7 thousand tonnes.

 

Cost of sales

 

In 2020, our cost of sales in our smelting segment decreased by 22.2%, or US$367.2 million, primarily due to (i) lower metal prices impacting the zinc concentrate purchase price; (ii) higher treatment costs paid to our smelters; (iii) the decrease in operating costs driven by lower energy, material and service costs in Peru; and (iv) the Brazilian real devaluation; partially offset by (v) the incremental costs related to the impact of COVID-19 and (vi) lower by-product credits. In 2019, our cost of sales in our smelting segment decreased by 11.9%, or US$223.7 million, primarily due to the decrease in average metal prices, increase in treatment charges and the depreciation of the real against the U.S. Dollar during the year.

 

116

 

 

Liquidity and Capital Resources

 

Liquidity and capital resources

 

Overview

 

In the ordinary course of business, our principal funding requirements are for working capital requirements, capital expenditures relating to maintenance and expansion investments, servicing our indebtedness and distributions to our shareholders. We typically meet these requirements through operational cash flows, long-term borrowings from private banks, the Brazilian Economic and Social Development Bank (Banco Nacional de Desenvolvimento Econômico e Social, or “BNDES”), international export credit agencies, and the issuance of debt securities in the international capital markets.

 

In response to the COVID-19 pandemic, we proactively managed our liquidity position by assuming additional debt during the first half of the year, adding approximately US$300 million to our cash balance through export credit notes issued in March and April, and the issuance of a US$500 million 7-year bond in June, with the net proceeds being used to repay certain existing financial indebtedness. Our financing strategy is to fund our necessary capital expenditures and to preserve our liquidity while meeting our debt payment obligations. We believe that our cash and cash equivalents on hand, cash from operations and available borrowings will be adequate to meet our capital expenditure requirements and liquidity needs for our current requirements. We may require additional capital to meet our longer-term liquidity and future growth requirements. Although we believe that our sources of liquidity are adequate, weaker economic conditions in Brazil, Peru or globally could materially adversely affect our business and liquidity.

 

Sources of funds

 

Our principal sources of funds are cash flows from operations and borrowings. The availability of cash flows from operations is affected by our working capital requirements, share premium reimbursements, dividends and investment activities, as well as a need to service our indebtedness. In 2020, our operating activities generated cash flows of US$291.7 million, compared to US$122.8 million in 2019, an increase of 137.5% primarily due to positive operating income and working capital gain. In addition, we assumed new debt, which proceeds were partially used to repay certain existing financial indebtedness.

 

Uses of funds

 

In the ordinary course of business, our principal funding requirements are used for capital expenditures, dividend payments and debt service. In 2020, we also used funds for liability management and repayment of debt, including the cash tender offer of US$214 million completed in February 2020 for our Nexa Peru Bonds due 2023.

 

Capital expenditures

 

Our capital expenditures in 2020 before tax credits amounted to US$354 million. We have accrued tax credits of US$18 million with respect to our ongoing projects. Consequently, net capital expenditures for 2020 totaled US$336 million. Of this amount, 66% was allocated to expansion projects driven by Aripuanã’s project evaluation (US$187 million) and Vazante’s mine deepening (US$13 million).

 

Non-expansion projects, which include sustaining and HSE, among others, accounted for 37% of the total capital expenditures (or US$133 million) in 2020. The main investments were related to sustaining capital expenditures.

 

For 2021, we have budgeted US$450 million to invest in projects that are currently underway. Our main projects include US$237 million directed towards expansion projects—of which US$232 million is allocated to construction of the Aripuanã project and US$2 million to the Vazante mine deepening project—and US$213 million towards non-expansion projects, which includes sustaining and HSE.

 

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Liquidity and Capital Resources

 

Expenses related to exploration and project evaluation

 

In 2020, exploration expenses were US$38 million, mainly driven by the resumption of our greenfield and brownfield exploration programs, including mine development. In mineral exploration, we continue our efforts to replace and increase mineral reserves and resources.

 

Project evaluation investment amounted to US$15 million in 2020, including approximately US$5.7 million directed towards greenfield projects in FEL1 and FEL2 stages and US$6.4 million to brownfield projects in the same stages.

 

We expect to continue to advance with our exploration and drilling campaigns and develop our pipeline of projects. In 2021, we estimate to spend US$71 million on expenses relate primarily to mineral exploration (US$51 million), which includes mineral rights and mine development, and project evaluation (US$20 million) activities.

 

Distributions and repurchases

 

On February 11, 2021, we announced that the board of directors approved a cash dividend of US$35 million (US$0.26 per share) to our shareholders of record as of March 12, 2021. The dividend will be paid on March 26, 2021.

 

On March 30, 2020, we paid approximately US$50 million (US$0.38 per common share) of dividends to our shareholders. Additionally, during the second quarter, our subsidiary Pollarix declared and paid dividends in the amount of US$5.3 million to the non-controlling interests owned by Votorantim Geração de Energia S.A. (“VGE”) which is a related party and US$0.1 million to Nexa.

 

On June 4, 2020, at our Extraordinary General Meeting (“EGM”), our shareholders approved the cancellation of the 881,902 shares held in treasury, repurchased in 2018 and 2019. Following the cancellation of the shares on June 4, 2020, VSA holds 64.68% of Nexa’s equity.

 

Debt

 

As of December 31, 2020, our total outstanding consolidated indebtedness (current and non-current loans and financings, including accrued interest as of December 31, 2020) is US$2,024.3 million, consisting of US$146.0 million of short-term indebtedness, including the current portion of long-term indebtedness (or 7.2% of the total indebtedness), and US$1,878.3 million of long-term indebtedness (or 92.8% of the total indebtedness).

 

Our U.S. dollar denominated indebtedness as of December 31, 2020 was US$1,570.0 million (or 77.6% of our total indebtedness), our Brazilian real-denominated indebtedness was US$451.6 million (or 22.3% of our total indebtedness) and our Peruvian sol-denominated indebtedness was US$2.7 million (or 0.1% of our total indebtedness).

 

As of December 31, 2020, US$568.2 million, or 28.1% of our total consolidated indebtedness, bears interest at floating rates, including US$337.6 million of real-denominated indebtedness that bore interest at rates based on the CDI rate, SELIC rate or Taxa de Juros de Longo Prazo (“TJLP”) and Taxa de Longo Prazo (“TLP”) rates (the long-term interest rates set by the Brazilian National Monetary Council and the basic costs of financing of the BNDES), and US$230.6 million of foreign currency-denominated indebtedness that bore interest at rates based on LIBOR.

 

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Liquidity and Capital Resources

 

The following table sets forth selected information with respect to our total outstanding consolidated indebtedness as of December 31, 2020.

 

        As of December 31, 2020  
    Average Annual Interest  

Current
Portion(1)
 

    Long-term
Portion
    Total  
                       
Indebtedness   Rate   (in millions of US$)  
Eurobonds   Fixed + 5.73%     22.9       1,316.1       1,339.0  
    LIBOR plus 1.27%     47.4       166.3       213.7  
Debt with banks   Fixed + 8.49%                        
    TJLP + 2.82%                        
BNDES   SELIC + 3.10%     9.6       170.2       179.8  
    TLP – IPCA + 5.43%                        
Debentures   107.5% CDI     5.2       5.2       10.4  
    LIBOR + 1.54%/                        
Export Credit Note         50.9       183.3       234.2  
    111.55% CDI                        
Other         10.0       37.2       47.2  
Total         146.0       1,878.3       2,024.3  

 

 

 

(1) Includes principal and interest.

 

As of December 31, 2020, US$180.2 million remains outstanding under our loan agreements with BNDES, US$91.6 regarding to the Nexa Dardanelos’ facility agreement which are guaranteed by Nexa Brazil and Nexa Resources, and US$88.6 regarding to Nexa Brazil’s facility agreement which are guaranteed only by Nexa Resources.

 

Some of our debt instruments also contain other covenants that restrict, among other things, our ability and the ability of certain of our subsidiaries to incur liens and merge or consolidate with any other person or sell or otherwise dispose of all or substantially all of its assets. These instruments also contained covenants requiring that we comply with certain financial ratios, including:

 

· a debt service coverage ratio of 1.0:1.0;

 

· a net debt to EBITDA ratio of 4.0:1.0; and

 

· a total debt to total capitalization ratio of 0.7:1.0.

 

As of December 31, 2020 we were in compliance with the above stated ratios.

 

Short-term indebtedness and revolving credit lines

 

Our consolidated short-term indebtedness, including the current portion of our long-term debt, was US$146.0 million, including principal and interest, as of December 31, 2020.

 

We maintain a US$300.0 million revolving credit facility with a syndicate of lenders that will mature on October 25, 2024. This facility is guaranteed by Nexa Brazil and Nexa CJM. If drawn, this facility will bear interest at three-month LIBOR plus 1.00% per annum. On April 14, 2020, in order to enhance our short-term liquidity, we fully drew down the revolving credit facility, which was subsequently repaid on June 23, 2020. As of December 31, 2020, no amounts were drawn under this facility.

 

We believe that we will continue to be able to obtain sufficient credit to finance our working capital needs based on current market conditions and our liquidity position. See “Risk factors—Financial risk— Our business requires substantial capital expenditures and is subject to financing risks.”

 

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Liquidity and Capital Resources

 

Long-term indebtedness

 

The following discussion briefly describes our principal financing agreements as of December 31, 2020. For additional information, see Note 26 to our consolidated financial statements.

 

Term Loan. On March 12, 2020, in order to reduce our cost of debt, enhance our short-term liquidity and manage our debt profile, we entered into a term loan with a global financial institution, in the principal amount of R$477.0 million (approximately US$100.0 million) at a cost of 8.5%, with a five-year maturity. Simultaneously, we contracted a swap to exchange the interest rate to 2.45% as well as the currency of debt service prepayments from Brazilian real to US dollar. The term loan is guaranteed by Nexa Resources.

 

Export Credit Notes. In March and April 2020, we entered into five Export Credit Note agreements in the total principal amount of R$1,477 million (approximately US$300 million) with maturity dates between one and five years and costs between 134.2% of CDI and CDI +1.8% up to CDI + 4.2%. In June 2020, we prepaid the principal and accrued interest of an Export Credit Note in the amount of US$96.4 million. In October 2020, we prepaid the principal and accrued interest of an Export Credit Note in the amount of US$40.0 million. As of December 31, 2020, our outstanding principal amount under the Export Credit Notes was US$233.6 million.

 

Export Prepayment Facilities. We have certain export credit facilities with different financial institutions. In June 2020, we prepaid US$100 million due under one of these export prepayment facilities. As of December 31, 2020, one of these export prepayment facilities remains outstanding in an amount of US$100.0 million and bears interest at a rate of six month LIBOR plus 1.27%. The outstanding export prepayment facility is guaranteed by Nexa Brazil and Nexa CJM and is secured by liens on certain collection accounts associated with the facility.

 

Nexa Resources Bonds due 2028. On June 18, 2020, we issued an aggregate principal amount of US$500.0 million in bonds maturing in 2028 and bearing interest at 6.500% per year. The bonds are guaranteed by our subsidiaries Nexa Brazil, Nexa Peru and Nexa CJM. As of December 31, 2020, the outstanding amount under these bonds was US$510.5 million, which is related to a principal amount of US$500.0 million plus an accrual of US$17.4 million related to interest, net of borrowing costs of US$6.9 million.

 

Nexa Resources Bonds due 2027. On May 4, 2017, we issued an aggregate principal amount of US$700.0 million in bonds maturing in 2027 and bearing interest at 5.375% per year. These securities are guaranteed by our subsidiaries Nexa Brazil, Nexa Peru and Nexa CJM. As of December 31, 2020, the outstanding amount under these bonds was US$698.7 million, which is related to a principal amount of US$700.0 million plus an accrual of US$6.0 million related to interest, net of borrowing costs of US$7.3 million.

 

Nexa Peru Bonds due 2023. On March 28, 2013, we issued an aggregate principal amount of US$350.0 million in bonds maturing in 2023 and bearing interest at 4.625% per year. On February 24, 2020, we completed a tender offer to purchase for cash any and all of the outstanding 2023 Notes and purchased an aggregate principal amount of US$214.5 million, or 62.55% of the outstanding principal amount as of the settlement of the tender offer. As of December 31, 2020, the outstanding amount under these bonds was US$129.7 million, which is related to a principal amount of US$128.5 plus an accrual of US$1.5 million related to interest, net of borrowing costs of US$0.3 million.

 

BNDES and FINEP. BNDES has been an important source of debt financing for our capital expenditures in Brazil. We, through our Brazilian subsidiaries, have entered into several loan agreements with BNDES for the expansion and modernization of certain fixed assets, studies and engineering projects, environmental investments and the acquisition of machinery and equipment. As of December 31, 2020, our aggregate outstanding principal amount under BNDES loan agreements was R$927.9 million or US$178.6 million. For further details on our long-term financings with BNDES, please see the table below.

 

On October 26, 2020, we disbursed the first tranche of the Credit Facility Agreement related to the Aripuanã Project signed with BNDES in the amount of approximately R$225 million or US$39.9 million at a cost of TLP plus 3.39%, with maturity in 2040. On December 28, 2020 we disbursed the second tranche of this facility in the amount of approximately R$250 million or US$47.7 million at a cost of TLP plus 3.39%, with maturity in 2040.

 

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Liquidity and Capital Resources

 

In December 2014, Nexa Brazil entered into a loan agreement with the Brazilian Financing Agency for Studies and Projects (Financiadora de Estudos e Projetos or “FINEP”), to finance the research and development of various projects. As of December 31, 2020, our outstanding principal amount under this loan agreement was R$5.7 million or US$1.1 million.

 

The following table sets forth selected information with respect to Nexa Brazil’s principal long term financings with BNDES and our outstanding amount under these financings as of December 31, 2020.

 

Indebtedness 

Borrower 

Guarantor 

Interest Rate 

Principal Payment Dates 

Maturity
Date 

Principal
Amount
Outstanding
As of
December 31, 2020 

            (in millions
of US$)
R$1,000.0 million BNDES Revolving Credit Agreement Nexa Brazil Nexa Resources TLP plus 2.09% per annum 120 monthly installments commencing on January 15, 2019 December 15, 2028 13.2
Total           13.2
  Nexa Brazil Nexa Resources SELIC plus 3.10% per annum 60 monthly installments commencing on October 15, 2021 September 15, 2026 30.6
R$1,200.0 million BNDES Revolving Credit Agreement (1) Nexa Brazil Nexa Resources TJLP plus 2.82% per annum 60 monthly installments commencing on September 15, 2017 September 15, 2026 16.8
  Nexa Brazil Nexa Resources TLP plus 2.22% per annum 120 monthly installments commencing on January 15, 2019 December 15, 2028 26.5
Total           73.9
Credit Facility Agreement Nexa Dardanelos Nexa Brazil and Nexa Resources TLP plus 3.39% per annum 210 monthly installments commencing on March 15, 2023 August 15, 2040 91.4
Total          

91.4

Total BNDES Long-Term
Indebtedness
         

178.5

 

 

 

 (1) Consists of three tranches.

 

Cash flows

 

The table below sets forth our cash flows from operating activities, investing activities and financing activities for the years ended December 31, 2020 and 2019.

 

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Liquidity and Capital Resources

 

    For the Year Ended December 31,  
    2020     2019  
    (in millions of US$)  
Consolidated Statement of Cash Flows Information                
Net cash flows provided by (used in):                
Operating activities     291.7       122.8  
Investing activities     (369.2 )     (335.4 )
Financing activities     451.6       (119.3 )
Effects of exchange rates on cash and cash equivalents     (16.1 )     (2.5 )
Other high liquid short term investments     29.5       -  
Increase (decrease) in cash and cash equivalents     387.5       (334.3 )
Cash and cash equivalents at the beginning of the year     698.6       1,032.9  
Cash and cash equivalents at the end of the year     1,086.2       698.6  

 

In 2020, our net cash flow provided by operating activities was US$291.7 million, primarily due to a lower interest paid on loans, financings and on lease liabilities, lower income tax paid, and a net positive impact of changes in operating assets and liabilities resulting from the Company’s initiatives during the COVID-19 pandemic to protect cash resources such as example renegotiated payment terms with vendors, offset by the premium paid on repurchased bonds.

 

In 2020, our net cash flow used in investing activities was US$369.2 million, mainly due to capital expenditures, which totaled US$323.7 million in 2020, partially offset by a net sales of financial investments of US$47.5 million.

 

In 2020, our net cash flow used in financing activities was US$451.6 million, mainly impacted by the assumption of US$1,296.5 million in new loans and financings, partially offset by the payments of loans and financings during the year in the amount of US$757.5 million and dividends paid in the amount of $56 million.

 

At December 31, 2020, our cash and cash equivalents were US$1,086.2 million, US$387.5 million higher compared to our cash and cash equivalents at December 31, 2019.

 

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Contractual Obligations

 

Contractual obligations

 

The following table sets forth certain of our contractual obligations as of December 31, 2020.

 

    Payments Due by Period  
    Total     Less than
1 year
    1 - 3 years     3 - 5 years    

More than

5 years

 
                               
    (in millions of US$)  
Loans and financings(1)     2,648.7       214.6       484.6       459.2       1,490.3  
Lease liabilities(2)     25.8       16.0       9.7       0.1       -  
Derivative financial instruments(3)     26.9       5.4       0.1       21.4       0.1  
Trade payables     370.1       370.1       -       -       -  
Confirming payable(4)     145.3       145.3       -       -       -  
Salaries and payroll charges     56.4       56.4       -       -       -  
Dividends payable     4.6       4.6       -       -       -  
Related parties     0.6       -       0.6       -       -  
Provisions - Asset retirement obligation(5)     377.9       33.7       53.5       70.4       220.2  
Use of public assets(6)     29.5       1.3       2.9       5.1       20.2  
Long-term commitments (7)     259.8       117.0       39.9       102.9       -  
Total     3,945.5       964.3       591.2       659.2       1,730.8  

 

 

(1) Reflects projected undiscounted cash flow of principal and interest as of December 31, 2020.

 

(2) Represents Nexa’s obligation to make lease payments arising from the lease.

 

(3) See Note 17 to our consolidated financial statements.

 

(4) Certain of our subsidiaries have entered into agreements extending payment terms from 90 to 180 days with several suppliers. These suppliers have discounted their receivables with banks.

 

(5) Represents the undiscounted cash flows to settle the provision for asset retirement, including interest to be incurred.

 

(6) Represents the amounts established in the concession contracts regarding the rights to hydroelectric power generation (onerous concession) under use of public assets agreements. The amounts are accounted in “Other liabilities” in our consolidated balance sheet.

 

(7) At December 31, 2020, we had contracted US$156.9 (December 31, 2019: US$211.3) of capital expenditures related to the Aripuanã project for the purchase of property, plant and equipment that have not yet been incurred. As part of our activities for the execution of certain Greenfield projects, we have agreed to minimum investments levels that, if not met by September 2024, would require additional disbursements of US$102.9.

 

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Off-Balance Sheet Arrangements

 

Off-balance sheet arrangements

 

As of December 31, 2020, we did not have off-balance sheet arrangements of the type that we are required to disclose under Item 5.E of Form 20-F.

 

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Critical Accounting Policies and Estimates

 

Critical accounting policies and estimates

 

The following discussion and analysis of our financial position and results of operations is based on our consolidated financial statements. The preparation of our consolidated financial statements requires us to make estimates and judgments that affect the reported amount of assets and liabilities, revenues and expenses and related disclosure of contingent assets and liabilities at the date of our consolidated financial statements. In the preparation of our consolidated financial statements, we believe that certain estimates and assumptions and other factors were reasonable and relevant. These estimates and assumptions are periodically reviewed, and adjustments are made to our consolidated financial statements, when appropriate. Each of the corresponding notes to our consolidated financial statements provides a detailed discussion of our significant accounting policies, as well as critical accounting estimates.

 

Critical accounting policies reflect significant estimates or judgments about matters that are both inherently uncertain and material to our financial position or results of operations. Below is a description of our critical accounting policies that require significant estimates and judgments.

 

Impairment of goodwill

 

We annually test whether goodwill has suffered any impairment, in accordance with the accounting policy stated in Note 33 to our consolidated financial statements. We assess the recovery of the carrying amount of goodwill of each cash generating unit or group of cash generating units based on value in use or fair value less costs to sell, using a discounted cash flow model.

 

We also assess, at each reporting date, whether there is an indication that goodwill may be impaired. If any indication exists, such as volume and price reductions or unusual events that can affect the business, we estimate the recoverable amount of the cash generating unit or group of cash generating units.

 

The process of estimating the value in use and the fair value less costs to sell involves assumptions, judgment and projections of future cash flows. Our assumptions and estimates of future cash flow used for impairment testing of goodwill are subject to risk and uncertainties, particularly for markets—such as metals— subject to higher volatilities, which are outside our control. The calculations used for the impairment testing are based on discounted cash flow models as of September 30, 2020, market assumptions, such as LME prices, market interest rates and other available data regarding global demand. The discount factor applied to the discounted cash flow model is our pre-tax weighted average cost of capital for the applicable region, adjusted for country-specific risk factors. These calculations use cash flow projections before taxes on income, based on financial and operational budgets for a five-year period. After the five-year period, the projections are extended to the end of the mine life for our mines and indefinitely for our smelters. We do not use growth rates in cash flow projections of the terminal value for our smelters.

 

Impairment analysis

 

When performing its annual impairment assessments, we identified the following impairment indicators:

 

· On March 31, 2020, we identified impairment indicators that arose mainly as a result of the decrease in short- and mid-term commodities prices, suspension of production, discontinued projects and increased operating costs. On September 30, 2020, we performed our annual impairment test for the CGUs to which goodwill had been previously allocated (Cerro de Pasco, Cerro Lindo and Cajamarquilla). Given that we assessed that there were new impairment indicators, we expanded the scope of this test to include all of NEXA’s CGUs. These impairment indicators included the decrease in the market long-term zinc price, which we assess as part of the strategic planning process performed during the third quarter of every year, as well as a result of the higher capital expenditures to be invested in the Cerro de Pasco CGU.

 

· In addition to the CGUs impairment analysis, for the year ended December 31, 2020, we have recorded impairment for individual assets, mainly regarding the Jarosite project, Ambrosia Mine and Atacocha underground mine operation as follows:

 

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Critical Accounting Policies and Estimates

 

o Jarosite: Due to problems with contractors and suppliers, in December 2019 the execution of this project was suspended. In 2020, we began studies to conclude its economical and operational viability, which are ongoing. Due to the uncertainties related to the project, an impairment was recognized.

 

o Ambrosia Mine: The Ambrosia mine in Morro Agudo reached the end of its life of mine during the fourth quarter of 2020 and operations were suspended due to the uncertainties associated with the geological model of the area, safety considerations and a greater movement of ore compared to the original plan. This suspension lead to an impairment recognition for the assets allocated in this mine.

 

o Atacocha Underground Mine: Due to the COVID-19 pandemic and its impact on the macroeconomic environment, the uncertain time for recovery and our efforts to reduce costs and improve operational efficiency, in June 2020 we suspended operations at the higher-cost Atacocha underground mine, placing it under care and maintenance. We have not yet determined how long the underground mine’s suspension will last and the decision will depend on an improvement in the mine’s economic viability. Due to this uncertainty, an impairment was recognized for the assets regarding Atacocha underground mine operation.

 

We concluded that the combination of these indicators could result in the recoverable amount of its cash-generating units being lower than the carrying amount. An impairment test of all our CGUs was performed. See Note 33 to our consolidated financial statement.

 

Fair value of derivatives and other financial instruments

 

We determine the fair value of financial instruments not traded in an active market by using valuation techniques. We use judgment to select among a variety of methods and make assumptions that are mainly based on market conditions existing at the end of each reporting period.

 

The main financial instruments and the assumptions we make for their valuation are described below.

 

· We consider the nature, terms and maturity of cash and cash equivalents, financial investments, trade accounts receivable and other current assets. The carrying amount of these items are similar to their respective fair value.

 

· Financial liabilities are subject to typical market interest rates. The market value is based on the present value of expected future cash disbursement, at interest rates currently available for debt with similar maturities and terms. We also consider Nexa’s credit risk when assessing the fair value of financial liabilities.

 

· The fair value of derivative financial instruments that we use for hedging transactions is evaluated by calculating their present value through yield curves at the closing dates. The curves and prices used in the calculation for each group of instruments are developed based on data from the Brazilian Securities, Commodities and Futures Exchange, Central Bank of Brazil, LME and Bloomberg, interpolated between the available maturities.

 

o Swap contracts: The present value of both the assets and liabilities is calculated through the discount of forecasted cash flows by the interest rate of the currency in which the swap is denominated. The difference between the present value of the assets and the liabilities generates its fair value.

 

o Forward contracts: The present value is estimated by discounting the notional amount multiplied by the difference between the future price in the reference date and contracted price. The future price is calculated using the convenience yield of the underlying asset. It is common to use Asian non-deliverable forwards for hedging non-ferrous metals positions. Asian contracts are derivatives in which the underlying asset price is the average price of certain assets over a range of days.

 

o Option contracts: The present value is estimated based on pricing methodologies such as the Black model, with assumptions that include the underlying asset price, strike price, volatility, time to maturity and interest rate. The underlying asset price is the average price of the foreign exchange rate in the fixing month.

 

126

 

 

Critical Accounting Policies and Estimate

 

Asset retirement obligations

 

Provisions are made for ARO, restoration and environmental costs when the liability arises due to the development or mineral production of an operating asset, based on the net present value of estimated closure costs. Our initial recognition and any subsequent revision of AROs also considers assumptions such as interest rates, inflation and useful lives of the assets. We review these estimates on a quarterly basis. Management uses its judgment and previous experience to determine the potential scope of restoration work that is required for the asset, as well as any related costs associated with such work.

 

The cash flows are discounted to present value using a credit risk adjusted rate that reflects current market assessments of the time value of money and the specific risks for the asset to be restored. The interest rate charges relating to the liability are recognized as an accretion expense in net financial results. Differences in the settlement amount of the liability are recognized in the income statement. For additional information, see Note 28 to our consolidated financial statements included herein.

 

Tax, civil, labor and environmental provision

 

We are party to ongoing labor, civil, tax and environmental lawsuits, which are pending at different court levels. We establish provisions for potentially unfavorable outcomes of litigation in progress and update them based on management evaluation, with support from the positions of external legal counsel. For additional information, see Note 29 to our consolidated financial statements.

 

Income tax and other taxes

 

We are subject to income tax in all countries in which we operate. Significant judgment is required in determining the income tax provision. The ultimate tax determination is uncertain for many transactions and calculations. We also recognize liabilities for anticipated tax audit issues based on estimates of whether additional taxes will be due. Where the final tax outcome of these matters is different from the amounts that were initially recorded, such differences will impact the current and deferred tax assets and liabilities in the period in which such determination is made. For additional information, see Note 11 to our consolidated financial statements.

 

Determination of Mineral Reserves and Mineral Resources as basis to determine life of mine

 

Mineral reserves are deposits estimated to be economically feasible for extraction under economic conditions as of the applicable measurement date. The amortization method and rates applied to the rights to use natural resources reflect the pattern in which the benefits are expected to be used by us and based on the estimated life of mine. Any changes to the life of mine, including as a result of changes in estimates of mineral deposits and mining plans, may affect prospective amortization rates and carrying values of these assets. The process of estimation of mineral deposits is based on a technical evaluation, which includes accepted geological, geophysics, engineering, environmental, legal and economic estimates. These estimates, when evaluated in the aggregate, can have a relevant impact on the economic viability of the mineral deposits. We use various assumptions with respect to conditions, such as metal prices, inflation rates, exchange rates, technology improvements and production costs, among others. Estimates of mineral reserves and resources are reviewed periodically, and any changes are adjusted to reflect life of mine and, consequently, adjustments to amortization periods. Costs for the acquisition of rights to explore and costs to develop mineral properties incurred as of the start of the feasibility study phase known as front end loading (“FEL 3”), are capitalized. Since April 1, 2018, these costs are amortized using the units of production method over the estimated useful lives of the mines. The impacts of the change in the accounting estimation were not considered to be material, and the change was accounted for prospectively. Once the mine is operational, these costs are amortized and considered a production cost.

 

Recently issued accounting standards and interpretations not yet adopted

 

For a discussion of new standards, interpretations and amendments to IFRS, see Note 5 to our consolidated financial statements.

 

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Risk Management

 

Risk management

 

Risk management is considered one of the key points in our business strategy and contributes to value creation and increasing the level of confidence in Nexa by its main stakeholders, including shareholders, employees, customers, suppliers and the local communities.

 

As a result, we have adopted an Enterprise Risk Management (“ERM”) Policy, that describes Nexa’s Risk Management Model, and its activities are an integral part of the processes in our operational units, corporate departments and projects, and provides support for decision-making by our executive officers and board of directors.

 

The risk assessment cycle is performed annually focusing on our strategy, operational aspects and key projects. We seek to identify material risks, which are then assessed with consideration of the potential health, safety, environmental, social, reputational, legal and financial impacts. By embedding risk management into our work processes and critical business systems, we work to ensure we make decisions based on relevant inputs and valid data. The material risks identified during the risk management process are monitored and reported to the executive team, audit committee and board of directors. We use a governance, risk and compliance management platform, BWise, to manage and assess our risks, to monitor our action plans and to create related reports.

 

We consider market risk to be the potential loss arising from adverse changes in market rates and prices. We are exposed to several market risks arising from our normal business activities. These market risks, which are beyond our control, principally involve the possibility that changes in commodity prices, interest rates or exchange rates will adversely affect the value of our inventory, financial assets and liabilities or future cash flows and earnings. For information on our risk management policies, see Note 12 to our consolidated financial statements.

 

Financial risk

 

Our financial risk management policy seeks to preserve our liquidity and protect our cash flow and its operating components (revenues and costs), as well as financial components (financial assets and liabilities) against adverse credit and market events such as fluctuations in currency and interest rates.

 

A significant portion of the products we sell are commodities, with prices based on international indices and denominated in U.S. dollars. A portion of our costs, however, are denominated in reais and soles, and therefore leads to a mismatch of currencies between our revenues and costs. Additionally, our indebtedness is based on different indices and currencies, which may impact our cash flows.

 

Our current financial risk management policy includes:

 

· Foreign Exchange Exposure Management. Foreign exchange exposure is our exposure to fluctuations in the currencies that make up our commercial, operational and financial relations (the real and sol), and that may impact our U.S. dollar cash flow. All actions in the financial risk management process are intended to hedge our cash flow in U.S. dollars, to maintain our ability to pay our financial obligations and to comply with liquidity and indebtedness levels defined by our management team. Our foreign exchange hedge mechanisms are based on the foreign exchange exposure that is projected at least for 12 months after a reference date.

 

· Interest Rate Exposure Management. Exposure to the interest rate is our exposure to fluctuations in each of the indices of interest rates (mainly CDI, LIBOR and TJLP) from loans and financing transactions and financial investment that may impact our cash flow. Interest rate fluctuations would also result in gains or losses in the market value of our fixed rate debt portfolio due to differences in market interest rates and the rates at the execution of the debt agreements.

 

· Commodity Exposure Management. Exposure to commodity prices is our exposure to income and operating costs fluctuations due to changes in the reference prices for commodities (e.g., zinc, copper, silver) based on demand, production capacity, producers’ inventory levels and commercial strategies and the availability of substitutes in the global market. We calculate our exposure at least for 12 months after a reference date, considering any derivative financial instrument that has a certain commodity as the underlying asset.

 

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Risk Management

 

· Counterparties’ and Issuers’ Risk Management. This policy establishes exposure limits for financial and non-financial institutions that are counterparties of financial transactions and/or issuers of debt securities. The purpose of our counterparties’ and issuers’ risk management is to mitigate the occurrence of negative impacts on our cash flows from the non-fulfillment of financial obligations by these issuers and counterparties. In the case of financial investments (cash allocation), we measure exposure to credit risk of issuers by the sum of gross balances of financial investments. In the case of derivative transactions, the credit risk exposure of a certain counterparty and transaction is measured by the pre-settlement risk using statistical models. Exposure limits are determined based on ratings assigned by rating agencies and the equity of the relevant financial institution.

 

· Liquidity and Financial Indebtedness Management. This policy establishes guidelines for managing our liquidity and financial indebtedness. The main instrument for measuring and monitoring liquidity is a cash flow projection, considering a minimum projection period of 12 months from the reference date. Liquidity and debt management considers as an objective the comparable metrics provided by global credit rating agencies for investment grade entities. With respect to indebtedness, metrics considered compatible with the relevant objective are considered.

 

All proposals must comply with the guidelines and rules set forth in our Financial Risk Management Policy and subsequently submitted for review by our finance committee and then for our board of directors’ approval, under the governance structure set forth in our Financial Risk Management Policy.

 

Foreign exchange risk

 

We are subject to foreign exchange risks resulting from the fluctuation of the real and the sol against the U.S. dollar, our functional currency. All actions in the financial risk management process related to our foreign exchange exposure are intended to hedge our cash flow in U.S. dollars, to maintain our ability to pay our financial obligations and to comply with liquidity and indebtedness levels defined by our management. We are also exposed to financial risk associated with changes in foreign currency exchange rates as certain costs incurred are in currencies other than our functional currency.

 

Assuming an exchange rate appreciation (devaluation) of 10.0% of the U.S. dollar against the real as of December 31, 2020, we estimate that our EBITDA for the year would have increased (decreased) by US$39 million for 2020. This calculation assumes that each exchange rate would change in the same direction relative to the U.S. dollar. In addition to the direct effects of changes in exchange rates, changes in exchange rates may also affect the volume of sales as other market participants become more or less competitive. This sensitivity analysis does not factor in a potential change in sales levels or actions that management could take to manage the potential impact. Accordingly, the actual effect of exchange rate fluctuations will vary from period to period. However, assuming all other factors are held constant, we would expect future fluctuations like those analyzed above to have a similar potential impact on our results for future periods. See “Forward-looking statements.”

 

Interest rate risk

 

A portion of our outstanding debt bears interest at variable rates and, accordingly, is sensitive to changes in interest rates. Based upon our indebtedness as of December 31, 2020, an increase/(decrease) in LIBOR of 25.0% would impact our profit and cash flows by US$243/(246) million. We calculate our exposure to fluctuations in interest rates at least for 12 months after a reference date, considering any derivative financial instrument that has certain index as the underlying asset. Based on these exposures, we prepare financial protection proposals, which are submitted for our finance committee’s approval. The hedges of interest rates, in general, seek to exchange fixed interest rate to floating interest rate or vice versa.

 

Metal price sensitivity

 

We are subject to financial risks arising from the volatility of prices of zinc, copper, lead and silver, and to a lesser extent gold. Assuming that expected metal production and sales are achieved, that tax rates are unchanged, and giving no effect to potential hedging programs, metal price sensitivity factors would indicate the following change in our 2020 Adjusted EBITDA (as previously defined) attributable to us resulting from metal price changes.

 

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Risk Management

 

   

Zinc

   

Copper

   

Silver

 
Change in metal price (in percentage)     10.0 %     10.0 %     10.0 %
Change in Adjusted EBITDA (in millions of US$)     87.4       17.2       12.7  

 

Derivative instruments

 

To hedge against financial risk, we enter derivative transactions under our Financial Risk Management Policy. Those transactions are carried out in the over-the-counter market under master agreements such as International Swaps and Derivative Association and Brazilian Contrato Geral de Derivativos (“CGD”) Agreements.

 

None of the derivative transactions we are party to as of December 31, 2020 have corporate guarantees or require margin calls or any kind of collateral. None of the derivatives we were party to as of December 31, 2020 was entered into for speculative or arbitrage purposes.

 

We have the following recurring hedge programs in place:

 

· Fixed price commercial transactions (customer hedge): Hedging transactions that convert sales at fixed prices to floating prices in commercial transactions with customers interested in purchasing products at fixed prices. The purpose of this strategy is to maintain the revenue flow of the business unit with prices linked to the LME prices. These operations usually relate to purchases of zinc for future settlement on the over-the-counter market.

 

· Hedges for mismatches of “quotation periods” (book hedge): Hedges that set prices for the different “quotation periods” between the purchases of certain inputs (metal concentrate) and the sale of products arising from the processing of these inputs, or different “quotation periods” between the purchase and the sale of the same product. These operations usually relate to purchases and sales of zinc and silver for future trading on the over-the-counter market.

 

· Hedges for “operating margin” (strategic hedge): Derivatives contracted to reduce the volatility of the cash flow from its zinc, copper and silver operations. With a view to ensuring a fixed operating margin in reais for a portion of the Brazilian production of metals, the mitigation of risks is carried out through the sale of zinc forward contracts with the sale of U.S. dollar forward contracts.

 

To execute our hedge programs, as well as any sporadic hedging demands, we and our subsidiaries mainly enter into average rate (Asian) forwards, collars and swaps and standard interest rate swaps. These are the types of derivatives applicable for the hedge of our exposures, according to our Financial Risk Management Policy.

 

We initially recognize derivative instruments at fair value on the date a derivative contract is entered into and subsequently re-measure at their fair value. The method of recognizing the resulting gain or loss depends on whether we designate the derivative as a hedging instrument, in the case of adoption of hedge accounting, and if so, the nature of the item being hedged. We adopt the hedge accounting procedure and designate certain derivatives as either:

 

· hedges of the fair value of recognized assets or liabilities or a firm commitment (fair value hedge); or

 

· hedges of a particular risk associated with a recognized asset or liability or a highly probable forecast transaction (cash flow hedge).

 

We document the relationship between hedging instruments and hedged items at the inception of the hedging transaction, as well as the risk management objective and strategy for the undertaking of the various hedge transactions. We also document our assessment, both at the inception of the hedge and on an ongoing basis, of whether the derivatives that are used in hedging transactions have been and will continue to be highly effective in offsetting changes in fair values or cash flows or fair values of hedged items.

 

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Major Shareholders

 

III. Share ownership and trading

 

Major shareholders

 

As of March 22, 2021, Nexa Resources has 132,438,611 common shares outstanding, with par value of US$1.00 per share. The table below sets forth the list of our shareholders and their participation in our capital stock.

 

Votorantim S.A. is Nexa Resources’ controlling shareholder. VSA does not have any different voting rights, but as long as it holds a majority of our voting stock, it can influence or control matters requiring approval by our shareholders, including the appointment of directors. VSA acquired all its shares in Nexa Resources on February 26, 2014.

 

Shareholder   Number     Share Capital (%)  
VSA     85,655,128       64.68 %
Public (1)     46,783,483       35.32 %
Total     132,438,611       100.00 %

 

(1) Includes 7,894,595 shares held by Capital International Investors (based on an amendment to Schedule 13-G filed by Capital International Investors on February 16, 2021), which represents 5.9% of our share capital.

 

VSA

 

As of March 22, 2021, Hejoassu Administração S.A., or Hejoassu, is the sole shareholder of VSA’s capital stock, which consists of 18,278,788,894 common shares. Hejoassu is indirectly wholly-owned by Ermírio Pereira de Moraes, Maria Helena Moraes Scripilliti, José Ermírio de Moraes Neto, José Roberto Ermírio de Moraes, Neide Helena de Moraes and the descendants of Antonio Ermírio de Moraes through controlled companies.

 

131

 

 

Related Party Transactions

 

Related party transactions

 

We enter transactions with VSA and companies that are owned or controlled, directly or indirectly, by VSA in our ordinary course of business. These transactions in the ordinary course of business are conducted on an arms’ length basis and in accordance with applicable laws and our corporate governance policies. See “Risk factors—Risks relating to our corporate structure—VSA has substantial control over us, which could limit our shareholders’ ability to influence the outcome of important corporate decisions.” In accordance with article 441-7 of the Luxembourg law of August 10, 1915 concerning commercial companies, as amended (“1915 Law”), any member of our board of directors having a direct or indirect financial interest conflicting with that of Nexa Resources in a transaction put before the board for consideration must advise the board thereof and cause a record of such member’s statement to be included in the minutes of the meeting. The director may not take part in these deliberations and at the next following general meeting of shareholders of Nexa Resources, before any other resolution is put to vote, a special report shall be made on any such conflicted transactions. This shall not apply where the decision of the board relates to ordinary business entered into under normal market conditions.

 

Nexa has controls in order to identify related parties on a quarterly basis and approve related party transactions. Such controls include an analysis by the related party internal committee which is a required step for the execution of related party transactions.

 

The table below sets forth the balances of our principal related party transactions as of the dates and periods indicated. The entities disclosed are entities part of the Votorantim Group. The transactions relate to shared project costs such as environmental protection; administrative services provided by the Center of Excellence (Centro de Excelência); sales of limestones and cement purchases, mainly for the Aripuanã project; purchases of energy to be used in Nexa Brazil operation units and construction services for the Aripuanã project, among others. For more information, see “Cost-sharing agreement with VSA,” “Other shared arrangements,” and “Purchasing of electricity from Votener.”

 

    As of
December 31,
 
    2020  
      (in millions of US$)  

Related Party Transaction Balances

       
Related Party Assets        
Current assets        
Trade Accounts Receivable        
Companhia Brasileira de Alumínio     1.5  
Votener - Votorantim Comercializadora de Energia Ltda     0.6  
Votorantim Cimentos S.A.     0.3  
Total     2.4  

Trade payables

       
Votorantim S.A.     0.8  
Andrade Gutierrez Engenharia S.A     1.2  
Companhia Brasileira de Alumínio     0.2  
Votorantim Cimentos S.A.     0.1  
Votener - Votorantim Comercializadora de Energia Ltda     6.3  
Votorantim International CSC S.A.C     0.4  
Other     0.9  
Total     9.9  
Dividends payable        
Other.     4.6  
Total     4.6  
Related parties liabilities        
Other     0.6  
Total     0.6  

 

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Related Party Transactions

 

We summarize below some of our principal related party transactions.

 

    For the Year Ended
December 31,
 
    2020  
      (in millions of US$)  
Related Party Transactions        
Sales        
Votorantim S.A.     -  
Companhia Brasileira de Alumínio     7.8  
Votener - Votorantim Comercializadora de Energia Ltda.     9.7  
Votorantim Cimentos S.A.     -  
Other     -  
Total     17.6  
Purchases        
Votorantim S.A.     4.4  
Andrade Gutierrez Engenharia S.A.     26.3  
Companhia Brasileira de Alumínio     1.2  
Votener - Votorantim Comercializadora de Energia Ltda.     7.7  
Votorantim Cimentos S.A.     0.5  
Votorantim International CSC S.A.C     6.6  
Other     0.8  
Total     47.5  

 

Cost-sharing agreement with VSA

 

We entered into an agreement with VSA on September 4, 2008, for services provided by the Center of Excellence (Centro de Excelência) of VSA related to administrative activities, human resources, back-office services, accounting, taxes, technical assistance, and training, among other activities. Under a cost sharing agreement, Nexa reimburses VSA for the expenses related to these activities that pertain to Nexa. We do not expect to negotiate any material changes in the terms and conditions of our cost-sharing agreement with VSA.

 

Andrade Gutierrez Engenharia S.A

 

As part of the execution of the Aripuanã project, in June 2019 we entered into a mining development services agreement with Andrade Gutierrez Engenharia S.A., in which one of our director’s close family members may have significant influence at its holding level. As of December 2020, the updated amount of this contract is US$52.7 million. In June 2020, we entered into one additional agreement with Consórcio Construtor Nova Aripuanã (a consortium of the Andrade Gutierrez group of companies) in connection with construction services for the Aripuanã project, in the total amount of US$21.3 million.

 

133

 

 

 

Related Party Transactions

  

Other shared arrangements

 

We have entered a number of shared services contracts with other entities in the Votorantim Group in an effort to achieve operational efficiencies. These include joint contracts for insurance coverage and information technology. Entities in the Votorantim Group with whom we maintain such contracts have access to a substantial level of information about us. In addition, VSA negotiates our insurance coverage at the level of the Votorantim group and we thus depend on choices made by VSA for selecting the service providers to be used for all insurances contracted by us, including coverage related to property, transport, liability, credit and engineering risk insurances. We retain the right of approval of contract renewal terms negotiated by VSA.

 

In addition, all executive officers participate in the Fundação Senador José Ermírio de Moraes (“FUNSEJEM”) pension fund, a private, closed and not-for-profit pension fund responsible for the management of the pension plans for the employees of companies linked to the Votorantim Group.

 

See “Risk Factors—Risks relating to our corporate structure—VSA has substantial control over us, which could limit our shareholders’ ability to influence the outcome of important corporate decisions.”

 

134

 

 

Distributions

 

Distributions

 

Distributions to our shareholders are subject to the requirements of Luxembourg law and the approval of our board of directors or our shareholders, as applicable, and will depend on a number of factors, including, but not limited to, our cash balance, cash flow, earnings, capital investment plans, expected future cash flows from operations, our strategic plans and cash dividend distributions from our subsidiaries, as well as legal requirements and other factors we may deem relevant at the time. As of December 31, 2020, there are no contractual restrictions on our ability to make distributions to our shareholders. Subject to these considerations, we estimate to distribute each year amounts equal to at least 2.0% of our average market capitalization. For this purpose, our average market capitalization for a fiscal year is the sum of the daily market capitalization for each NYSE trading date in such fiscal year divided by the number of NYSE trading days in such fiscal year, where the daily market capitalization for any trading day is the product of the NYSE closing price per share in U.S. dollars of our common shares on such trading day and the number of common shares outstanding on such trading day.

 

Each common share entitles the holder to participate equally in distributions, unless the right to distributions has been suspended in accordance with our articles of association or applicable law.

 

Distributions in our common shares may be made in the form of either dividends or reimbursements of share premium. Under Luxembourg law, dividends are determined by a simple majority vote at a general shareholders’ meeting based on the recommendation of our board of directors. Furthermore, pursuant to our articles of association, the board of directors has the power to declare interim dividends and/or proceed with reimbursements of share premium in accordance with the 1915 Law.

 

We and our subsidiaries are subject to certain legal requirements that may affect our ability to pay dividends or other distributions. Distributions to shareholders (including in the form of dividends or reimbursement of share premium) may only be made from amounts available for distribution in accordance with Luxembourg law, determined based on our standalone statutory accounts prepared under Luxembourg GAAP. Under Luxembourg law, the amount of a distribution paid to shareholders (including in the form of dividends or reimbursement of share premium) may not exceed the amount of the profits at the end of the last financial year plus any profits carried forward and any amounts drawn from reserves that are available for that purpose, less any losses carried forward and sums to be placed in reserve in accordance with Luxembourg law or our articles of association. Furthermore, no distributions (including in the form of dividends or reimbursement of share premium) may be made if at the end of the last financial year the net assets as set out in the standalone statutory accounts prepared under Luxembourg GAAP are, or following such a distribution would become, less than the amount of the subscribed share capital plus the non-distributable reserves. Distributions in the form of dividends may only be made from net profits and profits carried forward, whereas distributions in the form of share premium reimbursements may only be made from available share premium.

 

Luxembourg law also requires at least 5.0% of our net profits per year to be allocated to the creation of a legal reserve until such reserve has reached an amount equal to 10.0% of our issued share capital. If the legal reserve subsequently falls below the 10.0% threshold, at least 5.0% of net profits again must be allocated toward the reserve. The legal reserve is not available for distribution. As of December 31, 2020, the legal reserve is US$13,332,051.30.

 

The table below describes the distributions paid to our shareholders. Distributions for 2018 were paid in the form of a share premium reimbursements. Distributions for 2019 and 2020 were made in the form of a cash dividend.

 

    For the Year Ended December 31,  
    2020     2019     2018  
                   
    (in millions of US$)  
Distributions paid to shareholders     50.0       69.8       80.0  

 

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Distributions

 

On March 30, 2020, we paid approximately US$50 million (US$0.38 per common share) of dividends to our shareholders. Additionally, during the second quarter, our subsidiary Pollarix declared and paid dividends in the amount of US$5.3 million to the non-controlling interests owned by VGE which is a related party and US$2.1 million to Nexa.

 

On February 11, 2021, our board of directors approved the payment of a cash dividend of US$0.264273 per common share to our shareholders at the close of business on March 12, 2021 expected to be paid on March 26, 2021. The dividend will represent an aggregate amount of approximately US$35 million, based on the 132,438,611 common shares outstanding as of December 31, 2020. This dividend is subject to ratification, in accordance with Luxembourg laws, by our shareholders at the annual shareholders’ meeting for the fiscal year ended December 31, 2020, which is expected to occur in June 2021.

 

Nexa Resources is a holding company and has no material assets other than its ownership of shares in its subsidiaries. When Nexa Resources pays a dividend or other distribution on its common shares in the future, it generally causes its operating subsidiaries to make distributions to it in an amount sufficient to cover any such dividends or distributions. The ability of subsidiaries of Nexa Resources to make distributions to Nexa Resources is subject to their capacity to generate sufficient earnings and cash flow and may also be affected by statutory accounting and tax rules in Brazil and Peru, as well as any conditions under the corporate law applicable to each subsidiary.

 

A Luxembourg withholding tax of 15.0% is generally due on dividends and similar distributions made by Nexa Resources to its shareholders. However, distributions on Nexa Resources’ common shares that are sourced from a reduction of share capital or share premium are not subject to Luxembourg withholding tax if Nexa Resources does not have distributable reserves or profits in its standalone statutory accounts prepared under Luxembourg GAAP. See “Additional information—Taxation—Luxembourg tax considerations—Shareholders.”

 

There is no law, governmental decree or regulation in Luxembourg that would affect the remittance of dividends or other distributions by Nexa Resources to nonresident holders of its common shares, other than withholding tax requirements. In certain limited circumstances, the implementation and administration of international financial sanctions may affect the remittance of dividends or other distributions. There are no specified procedures for nonresident holders to claim dividends or other distributions.

 

Computershare Trust Company, N.A. is the paying agent for shareholders who hold common shares listed on the NYSE and on the TSX. Dividends and other distributions on our common shares will be declared and paid in U.S. dollars. Dividends and other distributions on common shares listed on the NYSE will be the same as for common shares listed on the TSX.

 

136

 

 

Trading Markets

 

Trading markets

 

Our publicly traded share capital consists of common shares with a par value of US$1.00 per share. Our common shares are publicly traded in the United States on the NYSE, under the ticker symbol NEXA. Our common shares are also publicly traded in Canada on the TSX, under the ticker symbol NEXA. On March 22, 2021, there were 132,438,611 common shares issued and outstanding.

 

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Purchases of Equity Securities by the Issuer and Affiliated Purchasers

 

Purchases of equity securities by the issuer and affiliated purchasers

 

Nexa did not repurchase any shares during 2020. As of December 31, 2020, there were no authorized share buyback programs.

 

138

 

 

Corporate Governance

 

IV. Corporate governance, management and employees

 

Corporate governance

 

Our corporate governance model is aimed at facilitating the flow of information between our executives and other key decision-makers on our management team, specifically, our board of directors, advisory committees and management committee. Our corporate governance model also provides a framework for the duties of our management team, including oversight of Nexa’s performance and decision-making. Our main corporate governance activities include support for board of directors, board advisory committees and executive board meetings; contribution to the process of preparing the annual report on governance practices; and elaboration of governance documents and updating of best practices.

 

Our corporate governance model is designed to ensure that the proper corporate governance principles are consistently applied within our organization. We have adopted certain corporate governance policies and practices in line with the Corporate Governance Guidelines ( “Canadian Corporate Governance Guidelines”) issued by the Canadian Securities Administrators pursuant to National Policy 58-201, together with certain related disclosure requirements pursuant to National Instrument 58-101— Disclosure of Corporate Governance Practices. These include adopting internal rules for the board of directors and appointing key committees that have independent representation and leadership, including an audit committee and a compensation, nominating and governance committee. The charter for the compensation, nominating and governance committee includes responsibility for reviewing and assessing the size, composition and operation of the board of directors to ensure effective and independent decision making, advising on potential conflicts of interest situations and developing corporate governance guidelines and principles. The disclosure set out below describes in further detail our approach to corporate governance in relation to the Canadian Corporate Governance Guidelines.

 

Code of conduct

 

We work with all of our employees, as well as third parties who interact with them, to ensure they behave in a manner consistent with our values, code of conduct and the key principles of our compliance program, particularly as these relate to the environment, human rights and labor related issues, health and safety, and anti-bribery and corruption. In 2018, we updated our compliance program based on the anti-corruption, anti-money laundering, anti-terrorist financing and antitrust laws in effect in the countries where we operate. As a result of this, the code of conduct was revised and is supported by compliance-related policies and procedures that were disseminated and implemented throughout the Company. Our directors and executives have certified that they have read and that they will comply with our code of conduct. Furthermore, our board of directors periodically monitors compliance related topics. A conduct committee is in charge of promoting the implementation of the code and supervising the application of disciplinary measures.

 

We have introduced several anti-corruption, anti-money laundering and antitrust initiatives, including, among other things, ethics and compliance training and an ethics hotline which enables employees and third parties to report misconduct. Information reported through our ethics hotline is investigated and following the investigation, disciplinary action may be taken, if necessary. We have not granted any implicit or explicit waivers from any provision of our code of conduct since its adoption.

 

Our code of conduct and main compliance-related policies are publicly available on our website at https://www.nexaresources.com. We will disclose future amendments to, or waivers of, our code of conduct on the same page of our corporate website. Information contained on our website is not incorporated by reference into this report, and you should not consider it to be part of this report.

 

Foreign private issuer and controlled company exemptions

 

Because we are a foreign private issuer, the NYSE rules applicable to us are considerably different from those applied to U.S. companies. Accordingly, we intend to take advantage of certain exemptions from NYSE governance requirements provided in the NYSE rules for foreign private issuers. Subject to the items listed below, as a foreign private issuer we are permitted to follow home country practice in lieu of the NYSE’s corporate governance standards. Luxembourg law does not require that a majority of our board consist of independent directors or the implementation of a compensation committee or nominating and corporate governance committee. As a foreign private issuer, we must comply with four principal NYSE corporate governance rules: (i) we must satisfy the requirements of Exchange Act Rule 10A-3 relating to audit committees; (ii) our chief executive officer must promptly notify the NYSE in writing after any executive officer becomes aware of any non-compliance with the applicable NYSE corporate governance rules; (iii) we must provide the NYSE with annual and interim written affirmations as required under the NYSE corporate governance rules; and (iv) we must provide a brief description of any significant differences between our corporate governance practices and those followed by U.S. companies under NYSE listing standards.

 

139

 

 

Corporate Governance

 

In addition, for purposes of the NYSE rules, as VSA beneficially owns a majority of our outstanding common shares, we are a “controlled company.” “Controlled companies” under those rules are companies of which more than 50.0% of the voting power is held by an individual, a group or another company. Accordingly, we are eligible to take advantage of certain exemptions from NYSE governance requirements provided in the NYSE rules. Specifically, as a controlled company under NYSE rules, we are not required to have a majority of independent directors or a compensation, nominating and corporate governance committee composed entirely of independent directors.

 

As described further above, we recognize that good corporate governance plays an important role in our overall success and in enhancing shareholder value and, accordingly, we have adopted certain corporate governance policies and practices that reflect our consideration of the recommended Canadian Corporate Governance Guidelines. The following table briefly describes the significant differences between our practices and the practices of U.S. domestic issuers under NYSE corporate governance rules.

 

Section

NYSE corporate governance rule for
U.S. domestic issuers

Our approach

303A.01 A listed company must have a majority of independent directors. “Controlled companies” and “foreign private issuers” are not required to comply with this requirement.

We are a controlled company because more than a majority of our voting power for the appointment of directors is controlled by VSA. We are a foreign private issuer because we are incorporated in Luxembourg. As a controlled company and foreign private issuer, we are not required to comply with the majority of independent director requirements.

 

Four of our ten directors are independent. Our board of directors has adopted internal rules equivalent to a charter. See “Corporate Governance, management and employees—Board of directors” for a description of our board and processes our board has implemented to promote the exercise of independent judgment.

 

303A.03 The non-management directors of a listed company must meet at regularly scheduled executive sessions without management. We have no management directors.

 

140

 

 

Corporate Governance

 

Section

NYSE corporate governance rule for
U.S. domestic issuers

Our approach

 

303A.04

A listed company must have a nominating/corporate governance committee composed entirely of independent directors, with a written charter that covers certain minimum specified duties.

 

“Controlled companies” and “foreign private issuers” are not required to comply with this requirement.

 

As a controlled company and foreign private issuer, we are not required to comply with the nominating/corporate governance committee requirements. However, we do have a compensation, nominating and governance committee composed of two independent directors and two non-independent directors, which has adopted a committee charter.

 

As set for in the committee’s charter, this committee is responsible for, among other matters:

 

·      identifying individuals qualified to be nominated as members of the board of directors;

·      suggesting names to fill any vacancies on the board of directors;

·      developing corporate governance guidelines and principles; and

·      evaluating the performance and effectiveness of the board of directors, the CEO and each of committees.

See “Corporate Governance, management and employees—Board of directors—Committees of our board of directors.”

 

303A.05

A listed company must have a compensation committee composed entirely of independent directors, with a written charter that covers certain minimum specified duties.

 

“Controlled companies” and “foreign private issuers” are not required to comply with this requirement.

 

As a controlled company and foreign private issuer, we are not required to comply with the compensation committee requirements. However, we do have a compensation, nominating and governance committee composed of two independent directors and two non-independent directors, which has adopted a committee charter.

 

As set forth in the committee’s charter, this committee is responsible for, among other matters:

 

·      reviewing and proposing new compensation models and changes to current compensation models; and

·      determining compensation of executive officers, directors and committee members.

See “Corporate governance, management and employees—Board of directors—Committees of our board of directors.”

  

 

141

 

 

Corporate Governance

 

Section

NYSE corporate governance rule for
U.S. domestic issuers

Our approach

303A.06

 

303A.07

 

A listed company must have an audit committee with a minimum of three independent directors who satisfy the independence requirements of Rule 10A-3 under the Exchange Act, with a written charter that covers certain minimum specified duties.

We have an audit committee composed of three members, all of whom qualify as independent under Rule 10A-3 and applicable NYSE standards. Each member of the audit committee also satisfies the financial literacy requirement under applicable standards. The audit committee has adopted a committee charter, which was duly approved by our board of directors.

 

As set forth in the committee’s charter, the committee shall assist the board of directors in fulfilling its oversight responsibilities with respect to:

 

·    quality and integrity of our financial reporting and related financial disclosures;

·    the effectiveness of our internal control over financial reporting and disclosure controls and procedures;

·     our compliance with legal and statutory requirements as they relate to financial statements and related financial disclosures;

·    our risk management controls and monitoring processes, according to the ERM policy; and

·    the qualifications, performance and independence of our independent auditors and performance of the internal audit function.

 

See “Corporate governance, management and employees—Board of directors—Committees of our board of directors.”

 

303A.08 Shareholders must be given the opportunity to vote on all equity-compensation plans and material revisions thereto, with limited exemptions set forth in the NYSE rules. Our articles of association require shareholder approval of overall remuneration, including any equity-compensation plans of members of the board of directors and members of board committees.
303A.09 A listed company must adopt and disclose corporate governance guidelines that cover certain minimum specified subjects. We have corporate governance policies in place as described in “Corporate governance, management and employees” in this annual report.

 

142

 

 

Corporate Governance

 

Section

NYSE corporate governance rule for
U.S. domestic issuers

Our approach

303A.10 A listed company must adopt and disclose a code of business conduct and ethics for directors, officers and employees, and promptly disclose any waivers of the code for directors or executive officers. We have adopted a formal code of conduct, which applies to our directors, officers, employees and third parties who interact with the Company. Our code of conduct has a scope that is similar, but not identical, to that required for a U.S. domestic company under the NYSE rules.
303A.12

(a) Each listed company CEO must certify to the NYSE each year that he or she is not aware of any violation by the Company of NYSE corporate governance listing standards.

 

(b) Each listed company CEO must promptly notify the NYSE in writing after any executive officer of the listed company becomes aware of any non-compliance with any applicable provisions of this Section 303A.

 

(c) Each listed company must submit an executed Written Affirmation annually to the NYSE. In addition, each listed company must submit an interim Written Affirmation as and when required by the interim Written Affirmation form specified by the NYSE.

As a foreign private issuer, we are subject to and comply with (b) and (c) of these requirements, but are not subject to (a).

 

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Board of directors

 

Our board of directors is responsible for the general guidance of our business and affairs, including providing general guidance, governance and strategic oversight to our executives and other members of our management team. It is also responsible for ensuring that we meet our objectives, as well as for monitoring our performance and ensuring business continuity. The board of directors is vested with broad powers to act on behalf of Nexa and to perform or authorize all acts of administrative or ancillary nature necessary or useful to accomplish our corporate purpose. All powers not expressly reserved by law to the shareholders fall within the competence of our board of directors.

 

Appointment and term of members of our board of directors

 

In accordance with our articles of association and the 1915 Law, the members of our board of directors are elected by a resolution of a general meeting of shareholders adopted with a simple majority of the votes validly cast, regardless of the portion of capital represented at such general meeting. Votes are cast for or against each nominee proposed for election to the board and cast votes shall not include votes attaching to shares for which the shareholder has not participated in the vote, has abstained or has returned a blank or invalid vote.

 

Our directors are appointed for a one-year term and may be reelected. Members of our board of directors may be removed at any time, with or without cause, by a resolution adopted at a general meeting of our shareholders. Under Luxembourg law, in the case of a vacancy of the office of a director appointed by the general meeting of shareholders, the remaining directors may, unless the articles of association provide differently, fill the vacancy on a provisional basis. In these circumstances, the following general meeting of shareholders shall make the final appointment of the director.

 

Composition of the board of directors

 

Our board of directors is comprised of a minimum of five and a maximum of eleven members and currently has ten members, of which four are independent directors and six are non-independent, as set out below.

 

In 2020, one director, Gianfranco Castagnola, was elected to our board for the first time. The term of each and all of our directors expires at the 2021 annual general meeting of shareholders. The following table sets forth our current directors, their respective board positions and their respective date of election to the board.

 

Name   Age     Principal Residence   Position   Elected Since
Jaime Ardila (3)     65     Aventura, USA   Chairman of the Board   June 18, 2019
Daniella Elena Dimitrov (1)(2)*     51     Toronto, Canada   Director   December 14, 2017
Diego Hernandez (2)     72     Vitacura, Chile   Director   August 25, 2016
Eduardo Borges de Andrade Filho (3) *     54     São Paulo, Brazil   Director   August 25, 2016
Edward Ruiz (1)(4)*     70     New Haven, USA   Director   December 14, 2017
Gianfranco Castagnola (4)     60     Lima, Peru   Director   June 4, 2020
Ian Wilton Pearce (2)     64     Toronto, Canada   Director   June 18, 2019
Jane Sadowsky (1)(3)*     59     New York City, USA   Director   December 14, 2017
João Henrique Batista de Souza Schmidt (4)     42     São Paulo, Brazil   Director   October 18, 2016
Luís Ermírio de Moraes (3)     60     São Paulo, Brazil   Director   August 25, 2016

 

 

 

(1) Member of the audit committee.

(2) Member of the sustainability and capital projects committee.
(3) Member of the compensation, nominating and governance committee.
(4) Member of the finance committee.

*     Independent pursuant to Rule 10A-3 under the Exchange Act (Rule 10A-3) and applicable NYSE standards, as well as National Instrument 52-110 and Section 311 of the TSX Company Manual.

 

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The business address of each member of our board of directors is our corporate office, which is 37A, Avenue J.F. Kennedy, L-1855, Luxembourg, Grand Duchy of Luxembourg.

 

We present below a brief biographical description of each member of our board of directors:

 

Jaime Ardila. Mr. Ardila has been a member of our board of directors since June 2019 and has been Chairman of the board since July 30, 2020. Mr. Ardila founded The Hawksbill Group in 2016, which provides business advisory services, including strategy, operations, public relations, communications and investment advice. Prior to that, he held several positions at General Motors Company in the U.S., Europe and South America in a career spanning 30 years. He also worked at the Planning Department and the Ministry of Industry and Trade for the government of Colombia from 1981 to 1984 and the investment bank Rothschild from 1996 to 1998. At General Motors, Mr. Ardila served CFO of General Motors Chile; President and Managing Director of General Motors Ecuador; President of General Motors Colombia; President of General Motors Argentina; CFO for Latin America, Africa and the Middle East; President for Brazil and Mercosur; and President of General Motors South America from 2010-2016. He is currently a member of the Board of Directors of Accenture and Chairman of Goldman Sachs, BDC. Mr. Ardila earned his master’s degree in Economics at the London School of Economics in 1981 and his bachelor’s degree in Economics at the University of Bogota in 1977.

 

Daniella Elena Dimitrov. Ms. Dimitrov has been a member of our board of directors since January 2018. Ms. Dimitrov has over 20 years of leadership experience in building, leading and operating businesses in mining and financial services, including as CEO, COO and CFO. She is currently a partner at Sprott Capital Partners, a division of Sprott Capital Partners LP, a merchant bank with a focus on natural resources. Ms. Dimitrov is also a director of International Petroleum Corp. and Chemtrade Logistics Income Fund and served as director of Excellon Resources Inc. until April 2020. Ms. Dimitrov’s previous roles include President and CEO and CFO of a multi-mine gold/copper producer; Executive Vice Chair of an iron ore developer through its acquisition following a hostile take-over bid; COO of a Canadian national wealth management and capital markets firm; and various corporate development roles in mining and financial services. Ms. Dimitrov has been a director of various mining companies and has served as a member and chair of various board committees, including audit, technical, health and safety, compensation and governance. Ms. Dimitrov has recently received the NACD Directorship Certification. She has a Global EMBA from Kellogg School of Management and Schulich School of Business and a law degree from University of Windsor. She was chosen as one of the top 100 Global Inspirational Women in Mining in 2016.

 

Diego Hernandez. Mr. Hernández has been a member of our board of directors since 2016. He was a member of the board of directors of Nexa Brazil until 2018. Mr. Hernández has over 45 years of experience in the mining industry. He is currently the President of the Sociedad Nacional de Minería in Chile and Advisor to the Chairman of BAL Group. He also integrates the Executive Committee of the Confederación de la Producción y del Comercio de Chile. He served as CEO of Antofagasta Minerals from August 2012, and in September 2014 was appointed CEO of Antofagasta plc, a position he held until April 2016. He was CEO of CODELCO in 2010/2012 and President of Base Metals in BHP Billiton and Chairman of Minera Escondida during 2004/2010, based in Santiago. He served as Executive Director, Non-Ferrous Metals in Vale in 2001/2004, CEO of Compañía Minera Doña Inés of Collahuasi in 1996/2001 and has held other senior positions in Anglo American and Rio Tinto. Mr. Hernandez received a civil mining engineer degree from the University of Chile and from the École Nationale Supérieure des Mines de Paris. In 2010, he received an award granted by the Copper Club of New York, and in 2013 the Chilean Institute of Engineers awarded him the “Gold Medal” for his distinguished career and important contribution to the development of engineering in Chile.

 

Eduardo Borges de Andrade Filho. Mr. Andrade has been a member of our board of directors since 2016. He was a member of the board of directors of Nexa Brazil until 2018 and has been member of the board of directors of CBA since 2017. Mr. Andrade has over 20 years of experience working with large industrial conglomerates and international consulting firms on relevant issues related to strategy, corporate development, corporate finance, governance and organization. He is founder and managing director of Otinga Investimentos, a private equity firm focusing on mid-size companies in Brazil. Between 2011 and 2014, he was corporate planning officer at VSA and served as board member of four other companies of the Votorantim Group. From 2010 to 2011, he was vice president for corporate development at Usiminas, a steel company, where he was responsible for mining and capital goods businesses, as well as strategy, business development and M&A. Prior to that, between 1997 to 2010, he was a Partner at McKinsey & Company, a consulting firm, where he took various leadership roles such as the Basic Materials Practice and the Knowledge Committee in Latin America. He started his professional career as an entrepreneur and engineer in his home state of Minas Gerais. Mr. Andrade received a bachelor’s degree in civil engineering from Fundação Mineira de Educação e Cultura in 1991 and holds a MBA from the University of Chicago in 1995.

 

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Edward Ruiz. Mr. Ruiz has been a member of our board of directors since January 2018. Mr. Ruiz brings over 48 years of experience in public and private accounting. Mr. Ruiz currently serves on the audit committee of several publicly traded companies in Brazil, including Iochpe-Maxion SA and Arezzo & Co. He is a Certified Public Accountant since 1972 and has been responsible for audits of companies in the mining and energy sectors in Brazil and the United States. Mr. Ruiz retired from Deloitte in 2012, where he was employed since 1997 and most recently served as an audit partner and member of Deloitte’s IFRS specialist group. As head of the Capital Markets group for Deloitte, Mr. Ruiz advised companies on financial and regulatory reporting matters related to initial public offerings and secondary offerings in the Brazilian, United States and European capital markets. Prior to Deloitte, he held executive positions in internal audit at JP Morgan and PepsiCo in the United States. He started his career in public accounting with Arthur Young in 1971. Mr. Ruiz obtained his bachelor’s degree from Pace University, New York City in 1971.

 

Gianfranco Castagnola. Mr. Castagnola has been a member of our board of directors since June 2020. Mr. Castagnola is partner and CEO of Apoyo Consultoría, a leading firm specialized in economic, business and financial advisory services in Peru. He also serves as chairman of the board of directors of its subsidiary, AC Capitales SAFI, one of the largest Peruvian investment fund managers. He has been a member of the board of directors of the Peruvian Central Bank from 1996 to 2001 and was president of the Universidad del Pacífico board of trustees. He is chairman of the board of directors of Scotiabank Peru S.A., and member of the board of directors of Saga Falabella, the Austral Group and IKSA. Mr. Castagnola’s previous roles include serving as member of the board of directors of Nexa Peru, Nexa Resources Atacocha S.A.A., Lima Airport Partners, Quimica Suiza, Cementos Pacasmayo, Camposol Holding and Redesur. Mr. Castagnola earned his master’s degree in public policy from Harvard University and his bachelor’s degree in Economics from the Universidad del Pacífico.

 

Ian Wilton Pearce. Mr. Pearce has been a member of our board of directors since June 2019. He served as CEO at Xstrata Nickel from 2006 to 2013, after which he launched X2 Resources, a mid-tier diversified mining and metals company, serving as one of its founding partners from 2013 to 2017. Prior to these roles, Mr. Pearce was responsible for the day-to-day management of several engineering, procurement and construction projects in South Africa, Zimbabwe, Chile, Canada, the United States, and Indonesia. Mr. Pearce has over 35 years of professional experience in metallurgy and mining-related industries and an extensive background in leadership positions including COO and Senior Vice President at Falconbridge, Limited, and as Project Engineer and Project Director with Fluor Inc. and Fluor Daniel Canada Inc. Currently, Mr. Pearce serves as chair and director on four public company boards and one private company board and one non for-profit organization. He also serves as advisor to the board of MineSense Technologies since 2013 and advisor to KoBold Metals since 2018. Mr. Pearce earned his Diploma in Mineral Process Engineering from University of Johannesburg and his bachelor’s degree from the University of Witwatersrand, both in South Africa. He also trained in general and strategic management at Wits Business School and Henley Business School. Mr. Pearce served as a member and Chair of the executive management boards at the Nickel Institute and the Mining Association of Canada, in addition to other professional affiliations.

 

Jane Sadowsky. Ms. Sadowsky has been a member of our board of directors since January 2018. Ms. Sadowsky has a broad and diverse range of finance and deal-related expertise and also has sector expertise in power and utilities and the related fields of commodities, renewables, power technology, infrastructure, and energy. She has a depth of knowledge and experience in mergers and acquisitions, public and private debt and equity, corporate restructurings and cross border transactions. Ms. Sadowsky retired from Evercore Partners, after more than 22 years as an investment banker. Prior to Evercore Partners, she worked in Citigroup’s Investment Bank and began her investment-banking career at Donaldson, Lufkin & Jenrette. Currently, Ms. Sadowsky serves on the board and the audit committee of Yamana Gold, a publicly traded gold mining company based in Toronto, Canada, and chairs Yamana’s governance committee. She also serves as a senior advisor with responsibility for diversity and inclusion at Moelis &. Company, a U.S. publicly traded company. Ms. Sadowsky earned her MBA from the Wharton School in 1989 and her bachelor’s degree in Political Science and International Relations from the University of Pennsylvania in 1983. She is a National Association of Corporate Directors Governance fellow and a frequent speaker at board governance conferences throughout the United States.

 

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João Henrique Batista de Souza Schmidt. Mr. Schmidt has been a member of our board of directors since 2016. He has held the position of executive officer for Corporate Development at VSA, and in 2020 he assumed the position of CEO. He is the Chairman of the Board of Directors of Votorantim Geração de Energia S.A., a position he has held since 2017 and he served as Chairman of the Board of Directors of CESP – Companhia Energética de São Paulo in part of 2019. He also served as member of the Board of Directors of Citrosuco S.A. from 2014 to 2019 and Nexa Brazil from 2016 to 2018. Mr. Schmidt was previously a member of the board of directors of Fibria Celulose S.A. from 2014 to 2019. Prior to joining VSA, Mr. Schmidt had 15 years of experience in the financial sector. Mr. Schmidt was a Managing Director of Goldman Sachs do Brasil Banco Múltiplo S.A., where he worked from April 2010 to August 2014, and prior to that worked at Citigroup and Goldman Sachs in different capacities. Mr. Schmidt received a bachelor’s degree in Business Administration from Fundação Getulio Vargas in 2001.

 

Luís Ermírio de Moraes. Mr. Moraes has been a member of our board of directors since 2016, and was the Chairman of the board until July 30, 2020. He was a member and the Chairman of the board of directors of Nexa Brazil until 2018. Mr. Moraes has over 35 years of experience working in mining and metallurgical operations. He is currently Vice President and a member of the board of directors of VSA, which is the Portfolio Manager Board of the Votorantim Group. Mr. Moraes is Chairman of CBA, the largest integrated aluminum producer in Brazil. He is a board member of Hejoassu, which is the ownership board of Votorantim. Mr. Moraes previous roles include director of VSA since 2000. Mr. Moraes also worked as an engineer in various processes in the areas of alumina refinery, smelter and aluminum smelting, pyrometallurgical and hydrometallurgical mineral processing of nickel laterites, developing novel projects for the separation and refining of cobalt. In the early 2000s, Mr. Moraes was the shareholder responsible for the creation and development of a new Votorantim business area with investments in IT and biotechnology. Mr. Moraes received a bachelor’s degree in mineral and chemistry engineering from the Colorado School of Mines, in the state of Colorado, United States, in 1982.

 

Internal rules of the board of directors

 

Our board of directors adopted board internal rules, which includes the following, among other things:

 

· approve the general guidance of our business, its mission, strategic goals and guidelines;

 

· ensure that the executive officers comply with such mission, strategic goals and guidelines;

 

· approve the budget and a strategic plan which takes into account, among other things, the opportunities and risks of the business;

 

· approve the annual commercial agreements strategy;

 

· recommend the shareholders to approve mergers, spin-offs, incorporations, acquisitions, divestitures and joint venture operations related to Nexa according to our articles of association;

 

· deliberate and approve any acts or transactions involving Nexa which have not been formally delegated to other corporate bodies, such as transactions with an individual amount of US$100.0 million or more, including any transactions relating to investments, loans or derivative contracts;

 

· promote and ensure compliance with our corporate purpose;

 

· ensure the sustainable, long-term continuity of Nexa, including with regard to economic, social and environmental considerations;

 

· develop our approach to corporate governance, including the creation and review, from time to time, of corporate governance principles and guidelines that are specifically applicable to us;

 

· evaluate the performance of our CEO and executive officers;

 

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· exemplify and, together with the management committee, create a culture of integrity throughout the organization;

 

· approve and monitor compliance with the following policies: (a) code of conduct; (b) disclosure policy; (c) insider trading policy; (d) dividend policy; (e) compliance policy; (f) antitrust/competition policy; (g) anti-corruption policy; (h) money laundering and terrorist financing prevention policy; (i) financial risk management policy (and complementary policies proposed by the management committee, such as the hedge, derivatives, leverage, liquidity and foreign exchange exposure policy); (j) ERM policy; and (k) authorization policy;

 

· approve board members and executive officers’ compensation, the amount of which shall not exceed the amount determined by the general meeting;

 

· ensure appropriate succession planning for our board of directors, CEO and executive officers;

 

· deliberate and approve the terms and conditions of any compensation arrangements or proposed material amendments to any terms and conditions of existing compensation arrangements entered into between Nexa and any of our executive officers; and

 

· all further tasks as required by applicable law and our articles of association.

 

The board internal rules are available on our website.

 

The board has at its disposal a set of provisions and practices that promotes independence in the decision-making process of the board. In accordance with the board’s internal rules, the independent members of the board may hold separate meetings and each director has a duty to declare, prior to any board meeting, the existence of a particular reason or conflict of interest with Nexa with respect to a subject matter being discussed or considered by the board. Accordingly, such board member would be refrained from discussing and voting on a matter that could present a conflict of interest. Additionally, our board members are prohibited from holding executive positions with Nexa and/or serving on more than four boards of directors of companies that do not belong to the same conglomerate. As discussed above, our audit committee is comprised entirely of independent directors and we also have independent representation on all other committees.

 

Description of the position of Chair

 

Our board of directors has developed a written position description for the chairman of the board of directors. The chairman of the board has the following responsibilities, subject to any other matters that may be set forth in our articles of association or provided for under applicable law:

 

· ensure the efficiency and proper performance of the board of directors;

 

· preside over the board meetings;

 

· prepare, organize, elaborate and distribute the agenda and minutes of the meetings aided by the board secretary, including all information necessary to discuss the matters on the agenda;

 

· coordinate the activities of other board members;

 

· ensure that all board members receive comprehensive information about the items on the board agenda in a timely manner;

 

· propose the annual corporate calendar to the board in coordination with Nexa’s CEO, which shall necessarily set forth the dates of corporate events;

 

· organize the onboarding and education sessions for incoming members of the board in coordination with Nexa’s CEO; and

 

· periodically arrange for continuing education opportunities for all board members, so that individuals may maintain or enhance their skills and abilities as members, and ensure that their knowledge and understanding of Nexa’s business remains current.

 

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The chairman of our board of directors is not an independent director of Nexa Resources. The board of directors has carefully considered governance issues relating to chairman independence and believes that the chairman carries out separate responsibilities diligently and that, with the compensating practices in place, the board of directors operates effectively and in Nexa’s best interest.

 

Meetings of the board of directors and attendance

 

The board of directors ordinarily meets in person or by other means of communication as may be required. The frequency of and agenda items for board meetings will vary depending on the state of affairs, requirements for approvals and opportunities available to Nexa and the risks and issues which Nexa faces. The agenda for meetings places priority and focuses on key issues for Nexa, which are identified by the chairman of our board. Routine business is dealt with after substantive discussions on the key issues.

 

Under the board of directors’ internal rules and our articles of association, the board can validly consider any matters and make decisions provided at least a majority of the members are in attendance in person or by representation. The board of directors’ internal rules further provides that each member is entitled to one vote either in person or where duly represented as required by the board’s internal rules. In fiscal year 2020, our board of directors held 11 meetings, in which the rate of attendance in person or by representation was 100% of the directors.

 

Director   Board
Meetings
    Meetings
Attended
    Overall %
Attendance
 
Jamie Ardila     11       11       100 %
Daniella Elena Dimitrov     11       11       100 %
Diego Hernandez     11       11       100 %
Eduardo Borges de Andrade Filho     11       11       100 %
Edward Ruiz     11       11       100 %
Gianfranco Castagnola (since June 4, 2020)     4       4       100 %
Ian Wilton Pearce     11       10       91 %
Jane Sadowsky     11       11       100 %
Jean Simon (until June 4, 2020)     7       7       100 %
João Henrique Batista de Souza Schmidt     11       11       100 %
Luís Ermírio de Moraes     11       11       100 %

 

As set forth in the board of directors’ internal rules, the independent directors may hold meetings in which members of the management team and the non-independent directors are not present. In 2020, our directors held in camera sessions without members of the management team prior and/or at the conclusion of each board meeting.

 

Committees of our board of directors

 

Our board of directors has an audit committee, a finance committee, a compensation, nominating and governance committee and a sustainability and capital projects committee. Our board of directors may have other committees as it may determine from time to time. Each of the standing committees of our board of directors has the composition and responsibilities assigned to them by the meeting of the board of directors that created such committee and as set forth in their respective committee charters. These charters set out, among other things, the roles and responsibilities of the chair of each committee. As set forth in the respective charters of the committees, each of the committees may meet with or without the management, as the case may be, at the discretion of the committee. The charter for each of the committees of our board of directors is available on our website.

 

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Audit committee

 

Our audit committee is a standing committee established by our board of directors on March 28, 2017 to assist the board of directors in fulfilling certain of its oversight responsibilities. The audit committee may be composed of three to five members, each appointed by our board of directors for a term of one year. Daniella Elena Dimitrov, Edward Ruiz and Jane Sadowsky currently serve as its members. These individuals are independent under Canadian securities regulators’ National Instrument 52-110 Audit Committees, as well as under Rule 10A-3 and applicable NYSE standards. In addition, each of them satisfies the financial literacy requirement under applicable rules. Our board of directors has determined that Mr. Edward Ruiz qualifies as an “audit committee financial expert.”

 

Our audit committee’s primary responsibilities are to assist the board of directors’ oversight of: (i) quality and integrity of our financial reporting and related financial disclosure; (ii) the effectiveness of our internal control over financial reporting and disclosure controls and procedures; (iii) our compliance with legal and statutory requirements as they relate to financial statements and related financial disclosures; (iv) the monitoring of risk management controls and processes, according to the ERM policy; (v) the compliance and ethics program; and (vi) the qualifications, performance and independence of our independent auditors and performance of the internal audit function.

 

Nexa has established policies and procedures that require any engagement of our independent auditor for audit or non-audit services to be submitted to and pre-approved by the audit committee. In addition, our audit committee may delegate the authority to pre-approve non-audit services to one or more of its members. All non-audit services that are pre-approved pursuant to such delegated authority must be presented to the full audit committee at its first scheduled meeting following such pre-approval. Our audit committee shall pre-approve all audit and non-audit services to be provided to us by our independent auditor and also has the authority to recommend pre-approval policies and procedures to our board of directors and for the engagement of our independent auditor’s services.

 

Finance committee

 

Our finance committee is a standing committee established by our board of directors on March 28, 2017 to assist the board of directors in fulfilling certain of its oversight responsibilities. The finance committee may be composed of three to five members, each appointed by our board of directors for a term of one year. Gianfranco Castagnola, Edward Ruiz and João Henrique Batista de Souza Schmidt currently serve as its members.

 

Our finance committee’s primary responsibilities are to assist the board of directors in fulfilling its oversight responsibilities with respect to monitoring Nexa’s balance sheet and by providing recommendations on our capital management strategy and capital structure, including indebtedness, investments and returns, among others.

 

Compensation, nominating and governance committee

 

Our compensation, nominating and governance committee is a standing committee established by our board of directors on March 28, 2017 to assist the board of directors in fulfilling certain of its oversight responsibilities. The compensation, nominating and governance committee may be composed of two to five members, each appointed by our board of directors for a term of one year. Luís Ermírio de Moraes, Eduardo Borges de Andrade Filho, Jaime Ardila and Jane Sadowsky currently serve as its members. Two of the four members of the compensation, nominating and governance committee are independent directors. An external advisor with broad experience in the area was retained from January to June 2020 to assist our compensation, nominating and governance committee in carrying out its mandate.

 

Our compensation, nominating and governance committee is responsible for: (1) new compensation models and changes to compensation models currently used by us, in order to guide and influence our actions; (2) the compensation of the executive officers, of the members of the board of directors and of the members of the committees of the board of directors; (3) the proposal of candidates to the chair of chief executive officer, when applicable, or any serious restrictions on the candidates proposed by the chief executive officer to the other chairs of the executive officers; (4) development of corporate governance guidelines and principles; (5) identification of individuals qualified to be nominated as members of the board of directors and suggesting nominees to fill any vacancies on the board of directors; (6) the structure and composition of board committees; (7) evaluation of the performance and effectiveness of the board of directors, the chief executive officer and each of the board’s standing committees; (8) the supervision and approval of our social responsibility plans and policies; and (9) any related matters required by applicable laws and stock exchange rules.

 

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Sustainability and capital projects committee

 

Our sustainability and capital projects committee is a standing committee established by our board of directors on April 29, 2019 to assist the board of directors in fulfilling certain of its oversight responsibilities. The capital projects oversight was added on December 3, 2020. The sustainability and capital projects committee may be composed of at least three and no more than five members, each appointed by our board of directors for a term of one year. Diego Hernandez, Daniella Elena Dimitrov and Ian Wilton Pearce currently serve as its members.

 

Our sustainability and capital projects committee’s primary responsibilities are to assist the board of directors by supporting safe and sustainable business practices in the conduct of our activities in respect of environmental, health, safety and social matters, including tailings management. The committee also assists in the oversight of the estimate and disclosure of mineral reserves and resources related to our operations and projects.

 

The sustainability and capital projects committee is also responsible for assisting the board with the review of technical, economic and social matters with respect to our projects, including exploration, development, permitting, construction and operation of our mining and smelting assets, which are core to our strategy and growth.

 

Orientation and continuing education

 

We implemented an orientation program for new directors under which each new director meets with the chairman of our board of directors and our executives. New directors are provided with comprehensive orientation and education as to our business, operations and corporate governance (including the role and responsibilities of the board of directors and each committee).

 

The chairman of our board of directors is responsible for overseeing directors’ continuing education and ensure that it is designed to maintain or enhance the skills and abilities of our directors and to ensure that their knowledge and understanding of our business remains current. The chair of each committee is responsible for coordinating orientation and continuing director development programs relating to the committee’s mandate.

 

Our ongoing director education programs entails site visits, presentations from outside experts and consultants, discussions on ongoing governance trends and guidelines for public companies, briefings from staff and management, and reports on issues relating to our projects and operations, sustainability and social matters, competitive factors, reserves, legal issues, economic, accounting and financial disclosure, mineral and hydrocarbon education and other initiatives intended to keep the board abreast of new developments and challenges that we may face.

 

Evaluation of directors

 

Our compensation, nominating and governance committee established a framework for the implementation and administration of processes to assess the effectiveness of the board and each of its members. This includes peer reviews of each director’s performance and self-assessments, as well as full board and committee review of the board and the respective committees, by way of questionnaires, interviews and sessions with the chairman. In addition to hiring external advisors to develop and undertake this assessment, the compensation, nominating and governance committee is also responsible for overseeing the process and evaluating the results, with the objective of improving the performance of each director and the board of directors as a whole.

 

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Considerations in evaluating director nominees

 

Our board of directors is responsible for nominating members for election to the board and for filling vacancies on the board that may occur between annual meetings of shareholders. The process for nominating a new director initiates with our compensation, nominating and governance committee which evaluates Nexa’s current circumstances and establishes a profile for a director candidate. Such profile is then shared with a specialized external executive search firm, who assists the compensation, nominating and governance committee in selecting candidates for interviews. Prior to the interview, the specialized external firm is responsible for a background check with former employers and colleagues of the respective candidates.

 

Following the interview(s), our compensation, nominating and governance committee recommends the nomination of the director candidate to our board of directors based upon an assessment of the independence, skills, qualifications and experience of such candidate. Specifically, the board seeks members from diverse professional and personal backgrounds who combine a broad spectrum of experience and expertise with a reputation for integrity.

 

Diversity

 

We value diversity of abilities, experience, perspective, education, gender, background, race and national origin. We believe that having a diverse board of directors can offer a breadth and depth of perspectives that enhance our performance. Recommendations concerning director nominees are based on merit and past performance as well as expected contribution to the board’s performance and, accordingly, diversity is taken into consideration. We believe that having a diverse and inclusive organization overall is beneficial to our success, and we are committed to diversity and inclusion at all levels of our organization to ensure that we attract, retain and promote the brightest and most talented individuals. We have recruited and selected executives that represent a diversity of business understanding, personal attributes, abilities and experience.

 

The compensation, nominating and governance committee and our board of directors have the responsibility to review and assess the composition of the board and each of its committees, and to identify, evaluate and recommend potential new directors. With respect to our executive officers, the compensation, nominating and governance committee reviews candidates recommended by the chief executive officer and makes the final recommendation to the board of directors. In new director and executive officer appointments and ongoing evaluations of the effectives of our board and management team, each of the board’s committees and each director, the board will take into consideration diversity as one of the factors in order to maintain an appropriate mix and balance of diversity, attributes, skills, experience and background on our board of directors and each of its committees and the management team. Ultimately, appointments to our board of directors and management team are based on merit against objective criteria and with due regard to the benefits of diversity in board and management team composition and the desire to maximize the effectiveness of corporate decision making, having regard to our best interests and strategies and objectives, including the interests of our shareholders and other stakeholders. During our selection process for board appointments, we seek to ensure that women candidates are always considered on the shortlist for nominations. Currently, two (or 20%) of our ten members of the board are women, and on a general basis, 13% of our overall employees are women.

 

Further, we developed a plurality program in 2019 as part of the Nexa Way program. This program is composed of affinity groups, which are formed by employees on a volunteer basis and divided into five themes: (i) women, (ii) race and ethnicity, (iii) LGBTQIA+, (iv) people with disabilities and (v) multigenerational. The affinity groups are assisted by a technical committee composed of executive officers and employees in key areas such as human resources, compliance, legal and institutional relations. By 2025, our gender target is to have 20% of women represented companywide. This target is frequently monitored, global and locally, and action plans are currently being implemented to achieve the proposed goal.

 

Compensation-setting process

 

Our compensation, nominating and governance committee is responsible for assisting our board of directors in fulfilling its governance and supervisory responsibilities, and advising our board of directors with respect to evaluation and monitoring of compensation models and policies performed every two years, which takes into account peer companies and the challenges and opportunities we face. The committee’s responsibilities also include administering and determining our compensation objectives and programs, reviewing and making recommendations to our board of directors concerning the level and type of the compensation payable, evaluating performance, implementing evaluation and improvement processes, and ensuring that policies and processes are consistent with our philosophy and the objectives of our compensation program.

 

Share ownership

 

Luís Ermírio de Moraes, a member of our board of directors, directly and indirectly owns 2,379,259, or 1.80%, of our common shares. As of December 31, 2020, none of our executive officers own, beneficially or of record, any of our common shares.

 

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Executive officers and management committee

 

Executive officers

 

We have global executives and management teams for our main subsidiaries. Each subsidiary team has a management structure that adheres to our corporate governance rules. Our executives currently are as follows:

 

Name   Age   Principal Residence   Position
Tito Botelho Martins Júnior   58   São Paulo, Brazil   President and Chief Executive Officer
Rodrigo Menck   46   São Paulo, Brazil   Senior Vice President Finance and Group Chief Financial Officer
Mauro Davi Boletta   60   São Paulo, Brazil   Senior Vice President Smelting
Leonardo Nunes Coelho   43   Lima, Peru   Senior Vice President Mining
Marcio Luis Silva Godoy   55   São Paulo, Brazil   Senior Vice President Project Development & Execution
Jones Aparecido Belther   53   São Paulo, Brazil   Senior Vice President Mineral Exploration & Technology
Felipe Baldassari Guardiano   58   São Paulo, Brazil   Vice President Sustainability, Strategic Planning & Corporate Affairs
Gustavo Cicilini   45   São Paulo, Brazil   Vice President Human Resources
Ricardo Moraes Galvão Porto   47   Lima, Peru   Senior Vice President Commercial & Supply Chain

 

The business address of our executives is Avenida Engenheiro Luís Carlos Berrini, n° 105, 6th floor, São Paulo, State of São Paulo, Brazil.

 

A brief biographical description of each of our executives is presented below:

 

Tito Botelho Martins Júnior. Mr. Martins has been our Chief Executive Officer since 2012. Mr. Martins has more than 30 years of experience in the metals and mining industry, and extensive board experience in different countries. Currently he serves on the board of CBA, as well as Nexa Peru and Nexa Resources Atacocha S.A.A., which are both listed in the Peruvian Stock Exchange. In 2014 and 2015, he was Chairman of the Board of the Brazilian Aluminum Association (“ABAL”). Prior to joining Nexa Resources, Mr. Martins was Executive Director for Base Metals at Vale S.A., a leading Brazilian mining company, from 2006 to 2012. During this period, he also served as board member of Norsk Hydro, an aluminum producer listed in Norway. He was also a member of the Brazilian Mining Institute. From 2003 to 2006, Mr. Martins was the CEO of Caemi S.A., a Brazilian diversified mining company listed on the São Paulo Stock Exchange. Earlier in his career, he worked for Vale S.A, from 1985 to 2003, where he held several positions in the finance and corporate areas. He graduated with a degree in Economics in 1984 from Universidade Federal de Minas Gerais in Brazil and has an MBA in 1984 from the Instituto de Pesquisa Economica e Administrativa of Universidade Federal do Rio de Janeiro, Brazil. In May 2017, the newspaper Valor Economico recognized Mr. Martins as the Valor Executive of the mining and metallurgy sector.

 

Rodrigo Menck. Mr. Menck has been our Senior Vice President Finance and Group Chief Financial Officer since March 2019. Mr. Menck has more than 20 years of experience in treasury, structured finance and capital markets. He joined Nexa Resources in 2016 as Head of Treasury & Investor Relations. He was also directly involved in Nexa Resources’ initial public offering in 2017 as well as Nexa Resources’ first debt issuance in May 2017. Prior to joining Nexa Resources, Mr. Menck held positions at BankBoston Corp., Itau Unibanco Holding S.A., WestLB A.G., Citibank and BNP Paribas S.A. He also worked at Braskem S.A. as a Structured Finance Manager and Finance and Shared Services Director and at Construtora Norberto Odebrecht S.A., as Head of Risk, Investments & Structured Finance (Latin America). Mr. Menck holds a degree in Business Administration and an MBA from the University of São Paulo, Brazil.

 

Mauro Davi Boletta. Mr. Boletta has been our Senior Vice President Smelting since 2016. Mr. Boletta has over 30 years of experience with operations. He joined Votorantim Metais S.A. in 1986, having served in several production areas. Between 2010 and 2011, he was responsible for the design review of an aluminum smelter in Trinidad and Tobago. Mr. Boletta graduated with a degree in electrical engineering from the Federal University of Itajubá, UNIFEI in 1985 and holds an MBA from FGV.

 

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Leonardo Nunes Coelho. Mr. Coelho has been our Senior Vice President Mining since 2017. Mr. Coelho has over 17 years of experience managing mining operations with focus at gold and zinc. Prior to joining us, Mr. Coelho worked for Anglo Gold Ashanti Ltd. for 15 years, where he initiated his career as a Trainee. In Anglo Gold Ashanti Ltd., Mr. Coelho has led mining operations and the expansion of mining projects and served as General Manager of the Cuiabá and Lamego complexes as his last position at this company. Mr. Coelho graduated with a degree in Mine Engineering in 2001 from the Federal University of the State of Minas Gerais (“UFMG”), and has obtained graduate degrees from the Kellogg Graduate School of Management in 2015 in the United States, the Dom Cabral Foundation in 2009 in Brazil and the University of Cape Town in 2005 in South Africa as well as a qualification at INSEAD in digital transformation in 2018.

 

Marcio Luis Silva Godoy. Mr. Godoy has been our Senior Vice President Project Development & Execution since June 2020 and has also been responsible for engineering and IT. Mr. Godoy has over 27 years of experience in the mining industry. He has worked in different roles related to mineral exploration, mineral technology, project development and implementation and mining operations in several countries including Brazil, Mozambique, Chile, Zambia, Australia and Suriname. Mr. Godoy previously worked in well-known companies including Vale, Phelps Dodge, Golden Star Resources and Novo Astro Mining. He was also the chairman of the Agency for the technological development of the Brazilian Mining Industry (“ADIMB”). Mr. Godoy is a graduated Geologist and has a Masters in Geology from the São Paulo State University (“UNESP”).

 

Jones Aparecido Belther. Mr. Belther has been our Senior Vice President Mineral Exploration & Technology since 2014. He has over 28 years of experience in the area. He held the same position at Votorantim Metais S.A. between 2004 and 2014. Prior to joining us, he was country manager at Vale in Peru between 2002 and 2004. He has worked in Brazil and abroad in companies such as Rio Tinto Brasil, Golden Star Resources, in Suriname, Phelps Dodge in Brazil and Chile, Vale in Brazil and Peru, and other companies. Mr. Belther graduated with a degree in Geology in 1991 from the São Paulo State University, UNESP, in Brazil, where he also obtained a Master’s degree in 2000 in Mineral Exploration.

 

Felipe Baldassari Guardiano. Mr. Guardiano has been our Vice President Sustainability & Strategic Planning since 2014 and has also been our Vice President for Corporate Affairs since 2019. Prior to that, he served as Director of Performance Management at Votorantim Metais S.A. between 2012 and 2014. He is responsible for developing and implementing company policies for sustainability and coordinating the elaboration and implementation of our strategic plan. In addition, he is responsible for establishing targets for performance improvement at all operations and corporate divisions through the development and implementation of the Votorantim Performance Management System. In 2012, before joining Votorantim Metais S.A., he worked at Vale for seven years as Director of Performance Management and, later, as a Director of Pellet Plants. Prior to Vale, he worked as a consultant, serving as an engagement manager associate at McKinsey & Co. for approximately five years. Prior to 1999, he lived in the United States for 12 years, where he worked as a Geostatistician and Reserve Specialist for Mineral Resources Development Inc. (“MRDI”). While at MRDI, he provided advisory expertise on mines in the United States, Canada, Africa, Brazil, Australia, Chile and other countries. Mr. Guardiano graduated in Mining Engineering from the Ouro Preto School of Mines (Minas Gerais, Brazil), and holds a Master’s degree in Mining Engineering from the Montana College of Mineral Sciences and Technology (Butte, Montana, United States), as well as executive education program certificates from the Massachusetts Institute of Technology (Boston, Massachusetts, United States), and the IMD (Lausanne, Switzerland).

 

Gustavo Cicilini. Mr. Cicilini became Vice President Human Resources in 2019. Mr. Cicilini joined Nexa Resources in 2018 as senior Human Resources manager for attraction, development and culture and has been responsible for leading a culture transformation program. He has over 20 years of professional experience in various business sectors, including telecommunication, food and beverage, mobility solutions, industrial technology, consumer goods, energy and building technology. He has previously worked in companies including Algar Telecom, AmBev and Robert Bosch and been located throughout Latin America, including in Peru, Colombia, Ecuador, Venezuela, Panama and Costa Rica. Mr. Cicilini previously worked as Regional Corporate Human Resources Project Manager and has been responsible for change management and innovation, business intelligence and cross-selling functions. He holds a degree in Psychology and an MBA in Business Administration.

 

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Ricardo Moraes Galvão Porto. Mr. Porto has been our Senior Vice President Commercial and Supply Chain since July 2018. His previous position was as Vice President Commercial and Supply Chain at Nexa, a position he held since 2014. Mr. Porto has also been Chief Executive Officer at Nexa Peru since November 2017. Mr. Porto held a management position at Votorantim Metais S.A. between 2013 and 2014. Mr. Porto began its career as commercial manager at Esso do Brasil, an Exxon Mobil affiliate. Prior to joining Votorantim Metais S.A., from 2004 until 2012, Mr. Porto worked in several senior management positions as supply chain executive at Vale S.A., reaching the position of officer Procurement Director. After, served as Executive Officer at the Bravante Group, an oil & gas company. Mr. Porto graduated with a degree in chemical engineering from the Federal University of Rio de Janeiro (“UFRJ”) and holds an Executive MBA from Fundação Dom Cabral. He has also obtained executive education program certificates from the Massachusetts Institute of Technology, and Kellogg Graduate School of Management in the United States and the IMD in Switzerland.

 

Evaluation of executive officers

 

On an annual basis, the performance of our executive officers is evaluated by the chief executive officer, the compensation, nominating and governance committee and ultimately, the board of directors. We strive to create a strong ethical and high performance culture, as well work to ensure an appropriate succession plan that ensures the continuity of our business. In addition to future business needs, we consider the core skills, experience and diversity necessary to carry out our strategy.

 

Each year, our chief executive officer presents to the board of directors a report on potential successors to his position, which considers the ability of succession candidates to succeed the chief executive officer in an emergency, on an interim or permanent basis, as well as critical experiences and other attributes required in order for each candidate to enhance his or her readiness for succession. Our board of directors discusses potential successors with the chief executive officers, as well as potential successors to each member of the management team.

 

Position descriptions

 

Our board of directors has developed position descriptions for each of the chief executive officer and chief financial officer, which are discussed below.

 

Chief executive officer

 

Our board of directors believes that our chief executive officer must have experience in, among other things: leading businesses of a similar complexity and scale; carrying out growth and value creation mandates; participating in mergers and acquisitions; articulating and executing long-term corporate strategies; and facilitating development within high achieving organizations. In addition, our board of directors expects our chief executive officer to have knowledge of the mining and metals industry, international experience and an extensive global network. According to our board of directors, our chief executive officer should possess the following attributes, among others: a hands-on approach to the business; an alignment with our values; resiliency and credibility; a good reputation within the market; and the ability to communicate with and influence stakeholders.

 

Chief financial officer

 

Our board of directors believes that our chief financial officer must have experience in, among other things: leading accounting, controllership, financial planning and analysis, investor relations, treasury matters, mergers and acquisitions and risk management activities; formulating a company’s plan and direction for the future; developing financial, operational and tax-related strategies; managing transactions; overseeing internal controls in compliance with applicable laws and regulations; and implementing all financial-related activities within a company. In addition, our board of directors expects our chief financial officer to have public company experience, strong analytical and business valuation skills and knowledge of national securities exchanges, such as the NYSE and TSX, international experience and an extensive global network. According to our board of directors, our chief financial officer should possess the following attributes, among others: a hands-on approach to the business; an alignment with our values; resiliency and credibility; a good reputation in the market; and the ability to communicate with and influence stakeholders.

 

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Management committee

 

In accordance with our articles of association, the board of directors may delegate its powers to conduct our management and affairs, as well as its representation of us with respect to such matters, to a management committee. The management committee consists of at least three, and a maximum of seven, members. The members are not required to be shareholders or directors of Nexa. The board of directors may not delegate its powers related to general guidance of our business or acts reserved to the board of directors pursuant to the 1915 Law.

 

The following table sets forth the members of our management committee, and their respective positions as of December 31, 2020. The term of the members of our management committee expires on the day of the first board meeting held after the 2021 general shareholders’ meeting.

 

Name   Age   Principal Residence   Position
Tito Botelho Martins Júnior   58   São Paulo, Brazil   President and Chief Executive Officer
Rodrigo Menck   46   São Paulo, Brazil   Senior Vice President Finance and Group Chief Financial Officer
Mauro Davi Boletta   60   São Paulo, Brazil   Senior Vice President Smelting
Leonardo Nunes Coelho   43   Lima, Peru   Senior Vice President Mining
Marcio Luis Silva Godoy   55   São Paulo, Brazil   Senior Vice President Project Development & Execution
Jones Aparecido Belther   53   São Paulo, Brazil   Senior Vice President Mineral Exploration & Technology
Ricardo Moraes Galvão Porto   47   Lima, Peru   Senior Vice President Commercial & Supply Chain

 

Conduct Committee

 

Our conduct committee reports to the Chief Executive Officer and was created on January 1, 2014. Its internal rules were revised and updated on December 2, 2019.

 

The conduct committee may be composed of at least seven members, such members being necessarily the Chief Executive Officer, the Senior Vice President of Finance and Group Chief Financial Officer, the Vice President of Human Resources, the Head of Internal Audit and Compliance, the Group General Counsel, the Compliance Manager and two representatives of the Ethics Line program, a confidential reporting system available to internal and external parties designed to allow anonymous reporting of violations of our code of conduct, policies and internal procedures or applicable laws.

 

Our conduct committee’s primary responsibilities are to assist the management committee in enforcing the code of conduct, reviewing any claims raised through the Ethics Line program, and identifying claims that should be rated as critical. The conduct committee also assists our audit committee by ensuring that any claim filed through the Ethics Line program and rated as critical is properly elevated to the audit committee for further review.

 

Family relationships among executives

 

Our executives do not have any family relationships among themselves or with any other of our employees.

 

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Executive and Director Compensation

 

Executive and director compensation

 

The following discussion describes the significant elements of the compensation of our executive officers and directors for the year ending December 31, 2020.

 

In 2020 our executive compensation program includes cash compensation in the form of base salary, short-term incentives and long-term incentives. We provide base salary to compensate executives for their day-to-day responsibilities, which is aligned to a market reference based on industry analysis. We evaluate our total compensation practices on an annual basis to ensure that our compensation remains competitive in light of market and industry trends.

 

Our compensation, nominating and governance committee is responsible for assisting our board of directors in fulfilling its governance and supervisory responsibilities and advising our board of directors with respect to evaluation and monitoring of compensation models and policies and other related matters. The committee’s responsibilities also include administering and determining our compensation objectives and programs, reviewing and making recommendations to our board of directors concerning the level and type of the compensation payable, evaluating performance, implementing evaluation and improvement processes, and ensuring that policies and processes are consistent with our philosophy and the objectives of our compensation program.

 

Compensation framework

 

Our compensation is comprised of three principal components: (i) base salary, (ii) short-term incentive and (iii) long-term incentive.

 

Principal elements of compensation

 

Base salary

 

Base salaries for executive officers are established based on the scope of their responsibilities and competencies and taking into consideration the median market reference. Adjustments to base salaries are expected to be determined annually and may be increased based on performance, as well as to maintain market competitiveness. Additionally, base salaries may be adjusted as warranted throughout the year to reflect promotions or other changes in the scope or breadth of roles or responsibilities.

 

Short-term incentive program / bonuses

 

The annual bonus or short-term incentive program aims to align short-term priorities with our strategic planning by rewarding achievement of our goals and targeted annual results, resulting in an alignment with our interests. Each named executive officer has a panel of individual goals, with scales of minimum performance, target and surpass results. Measurement in these panels is based on financial and non-financial indicators. These indicators represent the specific goals and challenges attributable to the position in alignment with our performance and strategic planning.

 

In response to the COVID-19 pandemic, we adjusted our goals, targeted annual results and weight distributions up to 50% of total potential earnings for executive officers, ensuring an agile and strategic approach to the market and the interests of shareholders. The directors also agreed to have their quarterly compensation reduced by 20% in the second and third quarters of 2020.

 

Financial indicators are based on internal metrics and represent up to 100% of the individual panel for corporate positions and up to 75% for operations positions. In 2020 the metrics used were EBITDA and free cash flow.

 

Strategic goals represent up to 70% of the individual panel and are comprised of qualitative and quantitative factors. In 2020, the metrics used in this assessment included performance targets related to cash cost, production volume, cost, safety and reserves and resources.

 

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Executive and Director Compensation

 

In 2020, the financial indicators applicable to our CEO represented up to 90% of the individual panel, and the metrics used were EBITDA and free cash flow. Strategic goals represented up to 10% of the individual panel reflecting Aripuanã project’s performance indicators.

 

Long-term incentive program

 

Our long-term incentive (“LTI”) program is designed to provide strong incentives for making decisions with a view to creating value for shareholders by linking cash compensation to our long-term performance, and by guiding executive actions towards the achievement of our strategic goals and growth plans.

 

The LTI program aligns interests among our executives and shareholders to ensure continued value creation. This incentive system is also intended to engage management in developing and delivering a consistent strategic plan, as well to attract and retain executive officers.

 

The LTI program is based on a five-year vesting period and comprised of three parts: (i) restricted grant, (ii) absolute performance grant and (iii) relative performance grant. All grants are defined amounts approved by the board of directors to be paid out at the end of the five-year vesting period. The restricted grant amount appreciates according to the total shareholder return (“TSR”) over the vesting period. The payment of the absolute performance grant is based on a targeted Company TSR combined with a performance curve, both approved by our board of directors at each granting period. The performance curve determines the amount to be paid in case of a performance equal or lower than expected in the targeted TSR. If the targeted TSR is achieved, the payment is fully due. If the performance of the TSR is greater than expected, the supplementary grant to be paid will be adjusted by up to 100%. The payment of relative performance grant depends on Nexa’s TSR performance when compared to a selected peer group approved by the board of directors.

 

The methodology is referenced to the market value of Nexa Resources’ shares at the end of the vesting period, calculated based on the weighted average price of the common shares during the months of October, November and December in the year immediately prior to the year in which the respective settlement date for the award occurs, together with dividends paid during the respective grant cycle.

 

Change of control

 

Upon the occurrence of a change of control event, all of the phantom shares will continue under the same terms, conditions and due dates, with the following exceptions:

 

· If Nexa terminates an executive’s employment without cause or if the executive resigns for good reason within 24 months of the change of control event, any unvested phantom shares will immediately fully vest as of the date of such termination or resignation for good reason. The exercise price will be calculated based on the weighted average price of the common shares during the three months immediately preceding the month of termination. In case termination occurs on the same date of the change of control event, the exercise price will be the share price (in US$/share) used as reference for the transaction that resulted in the change of control event.

 

· If the executive resigns within twelve months of the change of control event, he or she will be entitled to a portion of the granted shares, proportionate to the length of time served (1/60 for each 30-day period served), which will become immediately vested as of the date of resignation. The exercise price will be calculated based on the weighted average price of the common shares during the three months immediately preceding the month of resignation. The Board may approve special cases and adjust the aforementioned rules provided that the basic rights of the new shareholders as well as the executives are preserved.

 

Short selling

 

According to our insider trading policy, directors and officers must refrain from active or speculative trading involving Nexa’s securities based on short-term fluctuations in the price of Nexa’s securities or other market conditions. This includes, but is not limited to, short sales, trading in puts, calls or options or similar rights or obligations to buy or sell Nexa’s securities or derivative securities relating to Nexa’s securities, and the purchase of the Nexa’s securities with the intention of quickly reselling them. In addition, directors and officers may not purchase financial instruments, such as prepaid variable forward contracts, equity swaps or collars, designed to hedge or offset a decrease in the market value of Nexa’s securities.

 

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Executive and Director Compensation

 

2020 executive compensation

 

During fiscal year 2020, our executive officers received cash compensation in an aggregate amount of approximately US$6.6 million, which includes compensation paid to any officers whose terms ended on the first business day of 2020. The following table summarizes compensation we paid to our executive officers during the fiscal year 2020, including base salary, short-term incentive programs or bonuses, long-term incentive programs and pension value.

 

    Non-equity Incentive Plan Compensation  
Name and Title   Base Salary
(US$)
    Short-term
incentive
programs /
bonuses
(US$)
    Long-term
incentive
programs
(US$)
    Pension
Value
(US$)
    Total
Compensation
(US$)
 
Tito Botelho Martins Júnior
President and Chief Executive Officer
    597,088       706,662       1,004,273       32,243       2,340,266  
Rodrigo Menck
Senior Vice President Finance & Group Chief Financial Officer
    155,315       87,397       26,635       8,387       277,734  
Mauro Davi Boletta
Senior Vice President Smelting
    163,153       162,184       58,818       8,810       392,965  
Leonardo Nunes Coelho
Senior Vice President Mining
    399,734       242,973       58,818       10,302       711,827  
Valdecir Aparecido Botassini (1)
Senior Vice President Project Development & Execution
    361,343       160,437       194,038       3,941       719,760  
Marcio Luiz Silva Godoy
Senior Vice President Project Development & Execution
    171,463       -       -       4,337       175,800  
Jones Aparecido Belther
Senior Vice President Mineral Exploration and Technology
    171,403       163,898       149,565       9,256       494,121  
Gustavo Cicilini (2)
Vice President Human Resources
    132,665       128,252       -       6,989       267,905  
Ricardo Moraes Galvão Porto
Senior Vice President Commercial & Supply Chain
    365,845       277,259       142,067       8,981       785,151  
Felipe Baldassari Guardiano
Vice President Sustainability, Strategic Planning & Corporate Affairs
    173,699       135,459       157,188       18,759       485,105  

 

 

(1) Valdecir Aparecido Botassini was succeeded by Marcio Luiz Silva Godoy as Senior Vice President Project Development & Execution on June 1, 2020. The amount paid to Mr. Botassini includes termination costs.

 

(2) Gustavo Cicilini succeeded Arlene Domingues as Vice President Human Resources on November 1, 2019. An amount of US$499,689 was paid to Ms. Domingues in January 2020, covering all termination costs.

 

2020 director compensation

 

During fiscal year 2020, our directors received total compensation in an aggregate amount of US$1,900,700 for their services as members of our board of directors. The chairman of our board of directors received US$190,000 in annual fees, while each board member received an average of US$171,070. In addition, each director is entitled to reimbursement for reasonable travel and other expenses incurred in connection with attending board meetings and meetings for any committee on which he or she serves. In response to the COVID-19 pandemic, our board of directors voted to reduce their remuneration by 20% from April to December 2020 and the amount saved was added to resources to combat COVID-19.

 

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Executive and Director Compensation

 

We have no service contracts with members of our board of directors providing for benefits upon termination of employment.

 

Annual compensation levels for the directors are as set out below:

 

Name   Fees earned
(US$)
    Total
Compensation
 
Jaime Ardila     190,000       190,000  
Daniella Elena Dimitrov (1)     197,400       197,400  
Diego Hernandez     180,000       180,000  
Eduardo Borges de Andrade Filho     180,000       180,000  
Edward Ruiz (1)     201,900       201,900  
Gianfranco Castagnola (since June 4, 2020)     103,333       103,333  
Ian Wilton Pearce     180,000       180,000  
Jane Sadowsky (1)     197,400       197,400  
Jean Simon (until June 4, 2020)     90,000       90,000  
João Henrique Batista de Souza Schmidt     180,000       180,000  
Luís Ermírio de Moraes     200,667       200,667  

 

 

(1) The audit committee members are entitled to additional compensation of US$10,000.00 per year. The chair of the audit committee is entitled to additional compensation of US$15,000.00 per year. All audit committee members also receive an extra fee of US$1,500.00 per meeting attended.

 

Compensation consultants

 

We retained Korn Ferry as compensation advisors in 2020 to provide competitive market analysis to assist in determining the appropriate level of compensation for executives. Korn Ferry has over 40 years of experience and deep knowledge in the Brazilian market. Korn Ferry was asked to provide comprehensive competitive market clearing information on incentives, policies and benefits for each executive position. We paid Korn Ferry US$12,179.00 in consulting services fees in 2020.

 

We used survey reports compiled by the Bedford Consulting Group to assist in considerations related to board compensation. The Bedford Consulting Group’s mining industry reports offer in-depth analysis to support mining companies in benchmarking executive and director compensation practices relative to peer group competitors.

 

Retirement benefit plans

 

All executive officers participate in the FUNSEJEM pension fund, a private, closed and not-for-profit pension fund responsible for the management of the pension plans for the employees of the companies that are linked with the Votorantim group.

 

The pension plan is a defined contribution plan. Participation is voluntary and thus supplemental to the Brazilian government’s mandatory social security system. The plan is offered to employees through a specific fund that is maintained separately from the funds of each of the sponsoring organizations.

 

The plan’s assets correspond to 100% of the value of the liabilities. Annually, an actuarial assessment is made in compliance with the current legislation. However, there is no risk of deficit, since it is a defined contribution plan, whose formation of the reserve results from the capitalization of the respective contributions to the plan.

 

An employee may choose to contribute between 0.5% and 6.0% of his or her base wage. Nexa also matches the contribution made by the participant depending on such participant’s salary.

 

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Employees

 

Employees

 

As of December 31, 2020, we had 5,349 employees and 7,136 independent contractors. The following tables show the number of employees and contractors as of December 31, 2020, 2019 and 2018.

 

Number of Employees
    As of December 31,  
    2020     2019     2018  
Brazil     3,193       3,310       3,198  
Peru     2,131       2,427       2,367  
United States, Austria and Luxembourg     25       23       26  
Total     5,349       5,760       5,591  

 

Number of Independent Contractors*
    As of December 31,  
    2020     2019     2018  
Brazil     1,498       1,046       1,181  
Peru     5,638       5,984       5,574  
Total     7,136       7,030       6,755  

 

*Refers to fixed-term contracts only.

 

Most of our employees are represented by labor unions. We negotiate collective bargaining agreements, relating to salaries, working conditions and welfare, with the various unions that represent our employees. Although we believe our present labor relations are good, there can be no assurance that a work slowdown, stoppage or strike will not occur prior to or upon the expiration of the current collective bargaining agreements, and we are unable to estimate the effect of any such work slowdown, stoppage or strike on our production levels, in spite of an established contingency plan. In 2020, no material labor-related events happened in our units.

 

We regularly invest in programs that ensure employee development and meet our specific business needs while continuously enhancing the qualifications of our staff so as to maintain and reinforce our competitiveness and our know-how as we continue to grow. The training programs include Technical/Operative Trainings, Mentoring Program, Leadership Development Program, Young Professional Training and an Individual Development Plan that, among other things, indicates the training that a given employee requires in order to continue to grow within Nexa Resources. In addition, we have a Trainee Program and the Academy of Excellence, a program created by Votorantim for leaders within Votorantim.

 

161

 

 

 

Legal Proceedings

 

V. Additional information

 

Legal proceedings

 

As of December 31, 2020, we were party to various legal and administrative proceedings relating to labor, civil, environmental and tax matters in which the disputed amount for probable and possible claims was an aggregate of approximately US$318.5 million. It is our policy to make provisions for legal contingencies when, based upon our judgment and the advice of our legal counsel, the risk of loss is probable. As of December 31, 2020, we had established a net provision in the amount of US$30.9 million to cover contingencies for proceedings for which the risk of loss was deemed probable.

 

The following tables summarize judicial and administrative proceedings to which we are a party, the amounts in dispute in these proceedings in which a loss is considered probable or possible and the aggregate amount of the net provision established for losses that may arise from these proceedings.

 

    As of December 31, 2020  
    Total
Proceedings (1)
 
    Total Net
Provisions (2)
 
 
             
    (in millions of US$)  
Civil and other proceedings (3)     102.9       9.5  
Tax judicial and administrative proceedings     182.4       6.2  
Labor judicial and administrative proceedings     33.2       15.2  
Total     318.5       30.9  

 

 

 

(1) Does not include claims with expectation of loss classified as remote.

(2) Net of judicial deposits.

(3) Includes environmental legal and administrative proceedings.

 

Civil and environmental liabilities and contingencies

 

As of December 31, 2020, we were party to civil and environmental judicial and administrative proceedings, with a probable or possible chance of loss in the aggregate amount of US$102.9 million, for which we have recorded a net provision in the amount of US$9.5 million for proceedings with probable losses. The civil and environmental judicial claims filed against us primarily relate to pollution and collection lawsuits, repossession actions and indemnity actions related to contract disputes.

 

Tax liabilities and contingencies

 

As of December 31, 2020, we were party to tax-related judicial and administrative proceedings, with a probable or possible chance of loss in the aggregate amount of US$182.4 million, for which we have recorded a net provision in the amount of US$6.2 million for proceedings with probable losses.

 

The tax-related judicial and administrative claims filed against us primarily relate to (i) value added tax on sales and on transportation and telecommunication services (ii) corporate income tax and social contribution on net profit, (iii) CFEM, (iv) Programa de Integração Social (“PIS”) and (v) Contribuição para o Financiamento da Seguridade Social (“COFINS”).

 

Labor liabilities and contingencies

 

As of December 31, 2020, we were party to labor and employment benefits judicial and administrative proceedings, with a probable or possible chance of loss in the aggregate amount of US$33.2 million, for which we have recorded a net provision in the amount of US$15.2 million for proceedings with probable losses. The judicial and administrative claims related to labor benefits that were filed against us are mainly related to (i) overtime payments, (ii) compensation for illness-related damages and (iii) payment of social benefits.

 

162

 

 

Articles of Association

 

Articles of association

 

Company objectives and purposes

 

We were incorporated in Luxembourg as a public limited liability company (société anonyme) on February 26, 2014. Our articles of association provide that our corporate purpose is to, among others, (i) carry out any trade, business or commercial activities whatsoever, including but not limited to the purchase, exchange and sale of goods and/or services to third parties; (ii) take participations and interests, in any form whatsoever, in any commercial, industrial, financial or other, Luxembourg or foreign companies or enterprises; (iii) acquire through participations, contributions, underwriting, purchases or options, negotiation or in any other way any securities, rights, patents and licenses and other property, rights and interest in property as we shall deem fit; (iv) generally to hold, manage, develop, sell or dispose of the same, in whole or in part, for such consideration as Nexa Resources may deem fit, and in particular for shares or securities of any company purchasing the same; (v) enter into, assist or participate in financial, commercial and other transactions; (vi) grant to any holding company, subsidiary or sister company, or any other company that belongs to the same group as Nexa Resources, any assistance, loans, advances or guarantees (in the latter case, even in favor of a third-party lender of any affiliates); (vii) borrow and raise money in any manner and to secure the repayment of any money borrowed; and (viii) generally to do all such other things as may appear to Nexa Resources to be incidental or conducive to the attainment of the above objects or any of them. We can perform all commercial, technical and financial operations, connected directly or indirectly in all areas as described above, in order to facilitate the accomplishment of its purpose, provided always that Nexa Resources will not enter into any transaction that would constitute a regulated activity of the financial sector without due authorization under Luxembourg law.

 

Our common shares are governed by Luxembourg law and our articles of association. The following is a summary of the material terms of our common shares based on our articles of association and Luxembourg law. These rights may differ from those typically provided to shareholders of U.S. companies under the corporation laws of some states of the United States. We encourage you to read the complete form of our articles of association, filed as Exhibit 2.4 of this annual report on Form 20-F.

 

Common shares

 

On April 11, 2016, our shareholders approved the reduction of our share capital through the cancellation of 350,000,000 common shares, decreasing our share capital from US$1,280,505,254 to US$930,505,254.

 

On April 19, 2016, our shareholders approved the issuance of 110,910,811 new common shares fully paid via cash contributions by certain shareholders, increasing our capital from US$930,505,254 to US$1,041,416,065.

 

On June 28, 2017, our shareholders approved the reduction of our share capital through the cancellation of 200,000,000 common shares, decreasing our share capital from US$1,041,416,065 to US$841,416,065.

 

On September 18, 2017, our shareholders approved the reduction of our share capital through the cancellation of 300,000,000 common shares, decreasing our share capital from US$841,416,065 to US$541,416,065.

 

On October 6, 2017, our shareholders approved the reduction of our share capital through the cancellation of 428,595,552 common shares, decreasing our share capital from US$541,416,065 to US$112,820,513.

 

On October 31, 2017, our shareholders approved the issuance of 20,500,000 new common shares fully paid via cash contributions by certain shareholders, increasing our share capital from US$112,820,513 to US$133,320,513.

 

On September 13, 2018, our shareholders approved a general authorization to the board of directors to establish share buyback programs for a period of three years. On September 20, 2018, our board of directors approved a share buyback program under which we, directly or indirectly through our subsidiaries, may repurchase, from time to time, up to US$30.0 million of our outstanding common shares listed on the NYSE over a 12-month period beginning on November 6, 2018 and ending on November 6, 2019. As of March 25, 2019, we have repurchased 466,231 common shares, at an average price of US$10.63 per share, for an aggregate purchase price of US$4.96 million. All of the repurchased common shares were cancelled on June 4, 2020.

 

163

 

 

Articles of Association

 

On June 4, 2020, our shareholders approved the reduction of our share capital through the cancellation of 881,902 treasury shares, decreasing our share capital from US$133,320,513 to US$132,438,611.

 

As of December 31, 2020, our issued share capital was US$132,438,611 represented by 132,438,611 common shares fully paid, with par value of US$1.00 per share. In addition to our issued share capital, we have an authorized share capital of US$231,924,819, represented by 231,924,819 common shares.

 

Distributions

 

Pursuant to our articles of association, the general meeting of shareholders may approve dividends and the board of directors may declare interim dividends, in each case to the extent permitted by Luxembourg law. Pursuant to our articles of association, the board of directors may also declare distributions to our shareholders in the form of reimbursement of share premium or interim dividends to the extent permitted by Luxembourg law. Each common share entitles the holder to participate equally in any distributions, if and when declared by the general meeting of shareholders or, in the case of interim dividends or reimbursements of share premium, the board of directors, out of funds legally available for such purposes.

 

Declared and unpaid distributions held by us for the account of the shareholders shall not bear interest. Under Luxembourg law, claims for unpaid distributions will lapse in our favor five years after the date such distribution has been declared.

 

For additional information regarding our policy on distributions, including procedures provided by Luxembourg law, see “Share ownership and trading—Distributions.”

 

Voting rights

 

There are no restrictions on the rights of Luxembourg or non-Luxembourg residents to vote our shares. All of our shareholders, including our public shareholders, hold common shares with identical voting rights, preferences and privileges. Each common share entitles the shareholder to attend a general meeting of shareholders in person or by proxy, to address the general meeting of shareholders and to vote. Each common share entitles the holder to one vote at the general meeting of shareholders.

 

The board of directors may also decide to allow shareholders to vote by correspondence by means of a proxy form providing for a positive or negative vote or an abstention on each agenda item. The conditions for voting by correspondence are set out in the articles of association and in the convening notice.

 

The board of directors may decide to arrange for shareholders to be able to participate in the general meeting by conference call, video conference or similar means of communication, whereby (i) the shareholders attending the meeting can be identified, (ii) all persons participating in the meeting can hear and speak to each other, (iii) the transmission of the meeting is performed on an ongoing basis and (iv) the shareholders can properly deliberate without the need for them to appoint a proxyholder who would be physically present at the meeting.

 

General meeting of shareholders

 

In accordance with Luxembourg law and our articles of association, any regularly constituted general meeting of our shareholders has the power to order, carry out or ratify acts relating to our operations to the extent that such decisions are the domain of the shareholders and not the board of directors.

 

Our annual general meeting of shareholders shall be held at our registered office, or at such other place in Luxembourg as may be specified in the notice of the meeting, within six months after the end of the relevant financial year. Except as otherwise specified in our articles of association, resolutions at a general meeting of shareholders are adopted by a simple majority of shares present or represented and voting at such meeting.

 

A shareholder entitled to vote may act at any general meeting of shareholders by appointing another person (who need not be a shareholder) as his proxy, which proxy shall be in writing and comply with such requirements as determined by our board with respect to the attendance to the general meeting, and proxy forms in order to enable shareholders to exercise their right to vote. All proxies must be received by us (or our agents) no later than the day determined by our board of directors.

 

164

 

 

Articles of Association

 

Issuance of shares and preferential subscription rights

 

Our shares may be issued pursuant to a resolution of the general meeting of shareholders. The general meeting of shareholders may also delegate the authority to issue shares to the board of directors for a renewable period of five years. The board of directors has been authorized to issue up to 231,924,819 common shares. Such authorization will expire five years after the date publication in the Luxembourg legal gazette (Recueil Electronique des Sociétés et Associations) of the minutes of the of the general meeting of shareholders held on June 4, 2020 (unless amended or extended by the general meeting of shareholders).

 

Each holder of shares has preferential subscription rights to subscribe for any issue of shares pro rata to the aggregate amount of such holder’s existing holding of the shares. Each shareholder shall, however, have no preferential subscription right on shares issued for a contribution in kind.

 

Preferential subscription rights may be restricted or excluded by a resolution of the general meeting of shareholders, or by the board of directors if the shareholders so delegate. The general meeting of shareholders has delegated to the board of directors the power to cancel or limit the preferential subscription rights of the shareholders when issuing new shares, so long as the issuance of new shares is carried out through a public offering.

 

If we decide to issue new shares in the future and do not exclude the preferential subscription rights of existing shareholders, we will publish the decision by placing an announcement in the Luxembourg official journal Recueil Electronique des Sociétés et Associations and in a newspaper published in Luxembourg. The announcement will specify the period in which the preferential subscription rights may be exercised. Such period may not be shorter than 14 days from the publication of the offer. The announcement will also specify details regarding the procedure for exercise of the preferential subscription rights. Under Luxembourg law preferential subscription rights are transferable and tradable property rights.

 

Repurchase of shares

 

Nexa Resources is prohibited by the 1915 Law from subscribing for its own shares. Nexa Resources may, however, repurchase its own shares or have another person repurchase shares on its behalf, subject to certain conditions, including:

 

· prior authorization of the general meeting of shareholders setting out the terms and conditions of the proposed repurchase, including the maximum number of shares to be repurchased, the duration of the period for which the authorization is given (which may not exceed five years) and the minimum and maximum consideration per share;

 

· the repurchase may not reduce the net assets of Nexa Resources on a non-consolidated basis to a level below the aggregate of the issued share capital and the reserves that Nexa Resources must maintain pursuant to the 1915 Law or our articles of association;

 

· only fully paid-up shares may be repurchased; and

 

· the acquisition offer is made on the same terms and conditions to all the shareholders who are in the same position; however, listed companies may repurchase their own shares on the stock exchange without making an acquisition offer to the shareholders.

 

On September 13, 2018, our shareholders authorized us to purchase, acquire, receive or hold and sell shares of Nexa Resources in accordance with the 1915 Law and any other applicable laws and regulations. The authorization is effective immediately after the general meeting and valid for a period of three years. For more information, see “Share ownership and trading—Purchases of equity securities by the issuer and affiliated purchasers.”

 

165

 

 

Articles of Association

 

Form and transfer of shares

 

Our shares are issued in registered form only and are freely transferable. Luxembourg law does not impose any limitations on the rights of Luxembourg or non-Luxembourg residents to hold or vote our shares.

 

Under Luxembourg law, the ownership of registered shares is generally evidenced by the inscription of the name of the shareholder, the number of shares held by him or her in the shareholders’ register, which is maintained at our registered office. Each transfer of shares is made by a written declaration of transfer recorded in our shareholders’ register, dated and signed by the transferor and the transferee or by their duly appointed agent. We may accept and enter into its shareholders’ register any transfer based on an agreement between the transferor and the transferee provided a true and complete copy of the agreement is provided to us.

 

Our articles of association provide that, in case our shares are recorded in the register of shareholders on behalf of one or more persons in the name of a securities settlement system or the operator of such a system, or in the name of a professional depositary of securities or any other depositary or of a sub-depositary designated by one or more depositaries, Nexa—subject to a confirmation in proper form received from the depositary—will permit those persons to exercise the rights attaching to those shares, including admission to and voting at general meetings of shareholders. The board of directors may determine the requirements with which such confirmations must comply. Shares held in such manner generally have the same rights and obligations as any other shares recorded in our shareholder register(s).

 

166

 

 

Taxation

 

Taxation

 

Luxembourg tax considerations

 

Scope of Discussion

 

This summary is based on the laws of Luxembourg, including the Income Tax Law of December 4, 1967, as amended, the Municipal Business Tax Act of December 1, 1936, as amended and the Net Wealth Tax Act of October 16, 1934, as amended, to which we jointly refer as the “Luxembourg tax law”, existing and proposed regulations promulgated thereunder, and published judicial decisions and administrative pronouncements, each as in effect on the date of this report or with a known future effective date. This discussion does not generally address any aspects of Luxembourg taxation other than income tax, corporate income tax, municipal business tax, withholding tax and net wealth tax. This discussion, while not being a complete analysis or listing of all of the possible tax consequences of holding and disposing of shares, addresses the material tax issues. Also, there can be no assurance that the Luxembourg tax authorities will not challenge any of the Luxembourg tax consequences described below; in particular, changes in law and/or administrative practice, as well as changes in relevant facts and circumstances, may alter the tax considerations described below.

 

For purposes of this discussion, a “Luxembourg shareholder” is any beneficial owner of shares that for Luxembourg income tax purposes is:

 

· an individual resident of Luxembourg under article 2 of the Luxembourg Income Tax Law (“LITL”), as amended; or

 

· a corporation or other entity taxable as a corporation that is organized under the laws of Luxembourg or effectively managed from Luxembourg under article 159 of the Income Tax Law, as amended.

 

This discussion does not constitute tax advice and is intended only as a general guide. Shareholders should also consult their own tax advisors as to the Luxembourg tax consequences of the ownership and disposition of our common shares. The summary applies only to shareholders who will own our common shares as capital assets and does not apply to other categories of shareholders, such as dealers in securities, trustees, insurance companies, collective investment schemes and shareholders who have, or who are deemed to have, acquired their shares in the capital of Nexa Resources by virtue of an office or employment.

 

Shareholders

 

Luxembourg income tax on dividends and similar distributions

 

A non-Luxembourg shareholder will not be subject to Luxembourg income taxes on dividend income and similar distributions in respect of our common shares, other than a potential Luxembourg withholding tax as described below, unless the shares are attributable to a permanent establishment or a fixed place of business maintained in Luxembourg by such non-Luxembourg shareholder.

 

An individual Luxembourg shareholder will be subject to Luxembourg income tax on dividend income and similar distributions in respect of its shares in Nexa Resources at the applicable progressive rates. Such payments may benefit from a 50.0% exemption set forth in Article 115 15a of the LITL, subject to the conditions set out therein (or 50.0% exemption). If the 50.0% exemption applies, the applicable income tax will be levied on 50% of the gross amount of the dividends at the applicable progressive rates. Taxable dividends are also subject to dependence insurance contribution levied at a rate of 1.4% on the net income where certain Luxembourg shareholders are affiliated to the Luxembourg social security administration.

 

A corporate Luxembourg shareholder was subject to Luxembourg corporate income tax (“CIT”) and municipal business tax (“MBT”) at the aggregate rate of 24.94% in 2020 (i.e. Luxembourg CIT is 18.19% including the surcharge for the unemployment and MBT is 6.75% for having its statutory seat in Luxembourg City). The taxable basis of a corporate Luxembourg shareholder will, in principle, correspond to its accounting results, unless a specific treatment is provided for by the LITL. A corporate Luxembourg shareholder may benefit from the Luxembourg participation exemption (the “participation exemption”) with respect to dividends received if the following two conditions are met: (a) the shareholder holds or commits itself to hold at least 10.0% of the share capital of Nexa Resources or a participation with an acquisition price of at least €1.2 million for an uninterrupted period of at least twelve months and (b) the shareholder is a Luxembourg fully taxable corporation. If these cumulative conditions are met, dividends received by the corporate Luxembourg shareholder would be fully exempt from CIT and MBT at the level of the corporate Luxembourg shareholder.

 

167

 

 

Taxation

 

If the conditions with respect to the Luxembourg participation exemption are not met, the corporate Luxembourg shareholders can still benefit from the aforementioned 50.0% exemption, subject to the conditions set out therein.

 

Luxembourg withholding tax—Share capital reductions or share premium reimbursements

 

Share capital reductions or share premium reimbursements made by Nexa Resources to the Luxembourg and non-Luxembourg shareholders are in principle subject to a 15% Luxembourg withholding tax, unless they have been motivated by genuine economic reasons. Although genuine economic reasons are not defined by law, Luxembourg tax authorities may examine the given reasons. We do not intend to make capital reductions in the near future. Nexa Resources discloses distributable reserves, retained earnings and profits in its chart of accounts according to Decree dated June 10, 2009. As of December 31, 2020, we have the ability to pay dividends and not share premiums since Nexa Resources has accumulated profits. The share premium, if any, may be distributed to the shareholders in accordance with Luxembourg Commercial Companies Act by a resolution of the board of directors. See “Share ownership and trading—Distributions”.

 

Luxembourg withholding tax—Distributions to shareholders

 

A Luxembourg withholding tax of 15.0% is due on dividends and similar distributions made by Nexa Resources to its Luxembourg and non-Luxembourg shareholders unless a Luxembourg domestic dividend withholding tax exemption or a double tax treaty reduction is applicable, as described below. The tax will be withheld by Nexa Resources and remitted to the Luxembourg tax authorities within 8 days as of the date the income is made available to the Luxembourg and non-Luxembourg shareholders.

 

Exemption from Luxembourg withholding tax—Distributions to shareholders

 

Dividends paid by Nexa Resources will be exempt from Luxembourg withholding tax provided that the following cumulative conditions are met (or domestic exemption):

 

· at the date of the distribution, the shareholder holds at least 10% of the share capital of Nexa Resources or a participation with an acquisition price of at least €1.2 million for an uninterrupted period of at least twelve months; and

 

· the dividend is paid to a (i) fully taxable company resident in Luxembourg, (ii) a company resident in a EU Member State fulfilling the conditions of Article 2 of the Parent Subsidiary Directive and listed in the appendix to this directive, (iii) a company resident in a country with which Luxembourg has concluded a double tax treaty and which is fully subject to income tax comparable to the Luxembourg corporate income tax as well as a Luxembourg permanent establishment of such a company, (iv) a company resident of Switzerland and subject to tax without being exempt, (v) a company or a cooperative company resident in a Member State of the European Economic Area, other than a Member State of the EU, and that is fully subject to tax equivalent to the Luxembourg corporate income tax, or (vi) a Luxembourg permanent establishment of a company under (ii) or (v).

 

Shareholders that are companies resident in countries that have entered a double tax treaty with Luxembourg may qualify for the domestic exemption described above.

 

For a shareholder to benefit from such exemption upon a distribution date, Nexa Resources must file a properly competed form 900 with the Luxembourg tax authorities within 8 days following the earlier of (a) the distribution decision date in case no payment date is fixed, and (b) the effective date of payment of the dividend. Luxembourg tax authorities may request all relevant documentation showing fulfillment of the above-mentioned conditions (e.g., including a tax residency certificate). Nexa makes no representation that this exemption procedure will be practicable with respect to shares held through a clearing system such as DTC (in the United States) or CDS (in Canada).

 

168

 

 

Taxation

 

Alternatively, a shareholder may file a refund request (form 901bis, stamped and validated by the tax authorities of the State of residency of the shareholder) with the Luxembourg tax authorities before December 31 of the year following the taxable event (i.e., the distribution). Nexa makes no representation that this refund procedure will be practicable for a shareholder residing in the United States, Canada or any other specific jurisdiction.

 

A shareholder that does not meet the twelve-month holding period described in the first bullet above can request a refund when the twelve-month period has elapsed. The refund request (form 901bis, stamped and validated by the tax authorities of the State of residency of the shareholder) has to be filed with the Luxembourg tax authorities before December 31 of the year following the taxable event.

 

Forms 900 and 901bis are generally made available on the website of the Luxembourg tax authorities (Administration des contributions directes).

 

The application of the dividend withholding tax exemption to taxable companies’ residents in other EU member states or to their EU permanent establishments is not granted if the income allocated is part of a tax avoidance scheme.

 

Reduction of Luxembourg withholding tax—Distributions to shareholders

 

As mentioned above, pursuant to the provisions of certain bilateral treaties for the avoidance of double taxation concluded between Luxembourg and other countries, and if certain conditions are met, the aforementioned Luxembourg dividend withholding tax may be reduced. Many such treaties, including the double tax treaty with the United States, provide for a tax rate lower than 15 percent only for a shareholder that holds a substantial (generally, 10 percent or 25 percent) portion of a Luxembourg company’s shares. Shareholders that hold such shares should consult their tax advisors to determine how to benefit from the reduction in withholding tax rates.

 

A shareholder that is a company resident in a country that has entered a double tax treaty with Luxembourg may qualify for the domestic exemption even if the treaty would not reduce the withholding tax rate applicable to dividends paid to that shareholder.

 

Luxembourg NWT

 

A non-Luxembourg shareholder will not be subject to Luxembourg net wealth tax (“NWT”) unless the shares are attributable to a permanent establishment or a fixed place of business maintained in Luxembourg by such non Luxembourg shareholder.

 

Luxembourg individual shareholders are not subject to Luxembourg NWT. A Luxembourg corporate shareholder will be subject to Luxembourg NWT in respect of the shares held in the capital of Nexa Resources unless it holds more than 10% or €1.2 million of our common shares.

 

Luxembourg capital gains tax upon disposal of shares

 

Capital gains derived by a non-Luxembourg shareholder on the sale of our common shares will not be subject to taxation in Luxembourg, unless one of the following conditions applies:

 

· the shareholder does not benefit from a double tax treaty and (i) holds shares in Nexa Resources representing more than 10% of the share capital of Nexa Resources and such shares were held for less than six months prior to their sale or (ii) has been a resident taxpayer in Luxembourg for at least fifteen years and had acquired nonresident status less than five years prior to the disposal; or

 

· Our common shares are attributable to a permanent establishment or a fixed place of business maintained in Luxembourg by such non-Luxembourg shareholder. In such case, the non-Luxembourg shareholder is required to recognize capital gains or losses on the sale of such shares, which will be subject to CIT and MBT, unless the participation exemption applies.

 

169

 

 

Taxation

 

Capital gains realized upon the sale of our common shares by a Luxembourg resident individual will be subject to Luxembourg income tax at the level of the Luxembourg resident individual only in case of (i) speculation gains or (ii) gains realized on a substantial participation.

 

Speculation gains

 

Capital gains realized upon the sale of our common shares within a shareholding period not exceeding six months will be subject to personal income taxation (unless such capital gain does not exceed €500) in the hands of a Luxembourg resident individual.

 

Substantial participation

 

In case where the Luxembourg resident individual has held the shares for at least six months and had a substantial participation, the capital gains realized will be subject to income tax at a rate equal to half the normal progressive rate applicable. A participation is considered as a substantial participation when a Luxembourg resident individual, jointly with his/her spouse and children under the age of 18, holds or has held, directly or indirectly, at any time during the five years prior to the date of the sale, 10.0% or more of the share capital of Nexa Resources.

 

Capital gains realized by the Luxembourg corporate shareholder (société de capitaux) should be exempt from capital gains tax in Luxembourg if at the date of the disposal, the Luxembourg shareholder has held or undertakes to hold, for an uninterrupted period of at least 12 months, a direct participation which represents at least 10.0% of the share capital of Nexa Resources, or which acquisition price was at least €6.0 million. If these conditions are not met, the Luxembourg corporate shareholder would be fully taxed on the capital gains realized upon the sale of the common share. The exempt amount of the capital gains realized will be, however, reduced by the amount of any expenses related to the participation, including decreases in the acquisition cost that could have previously reduced such shareholder’s Luxembourg taxable income.

 

ATAD rules

 

The European Council has adopted two Anti-Tax Avoidance Directives: Council Directive (EU) 2016/1164 of 12 July 2016 laying down rules against tax avoidance practices that directly affect the functioning of the internal market (“ATAD I”) and Directive 2017/952/EU of 29 May 2017 amending ATAD I as regards hybrid mismatches with third countries (“ATAD II”) that address many of the issues mentioned above. The measures included in ATAD I were implemented into Luxembourg law on December 21, 2018 and almost all of them have been applicable since January 1, 2019. The measures included in ATAD II were implemented into Luxembourg law on December 19, 2019 and almost all of them have been applicable since January 1, 2020. ATAD I and ATAD II may have a material impact on how returns to shareholders are taxed.

 

Peruvian tax considerations

 

The following is a general summary of material Peruvian tax matters, as in effect on the date of this report, and describes our understanding of the principal tax consequences of an investment in our common shares by a person or entity who is not considered a resident of Peru for tax purposes. This summary is not intended to be a comprehensive description of all the tax considerations that may be relevant to a decision to make an investment in the offered shares.

 

This summary is based on provisions of the Peruvian income tax law and its regulations in force as of the date hereof. No rulings from the Peruvian tax authorities or judicial rulings address the tax treatment of instruments similar to the shares of Nexa Resources. Accordingly, no assurance can be given that the Peruvian tax authorities will agree with the conclusions described below. If the Peruvian tax authorities were to take a position different from the conclusions described below, the Peruvian income tax consequences of investing in Nexa Resources may differ from those summarized below.

 

Sale, exchange or disposition of the shares or a beneficial interest therein

 

Investors who decide to invest in the shares of Nexa Resources hold the shares in book-entry form, in the name of a nominee holding such shares for the investors’ benefit. Any future trading of such shares will be effected through a conveyance of the beneficial interest held by the investors thereupon through the designated clearing mechanism. Because the conveyance of such beneficial interest does not imply the actual transfer of shares, any capital gains resulting from the conveyance of the beneficial interest in such shares, obtained by a person or entity who is not considered a resident of Peru for Peruvian tax purposes, should not be subject to taxation in Peru.

 

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Taxation

 

Contrary to the conclusion stated above, if the sale of our common shares were to qualify as an “indirect transfer of Peruvian shares” (and the transfer of the beneficial interest in the shares were to be considered as an actual transfer of such shares), different rules would apply.

 

According to Peruvian income tax law, an “indirect transfer of Peruvian shares” is deemed to occur when there is a transfer of shares issued by a non-resident company which, in turn, owns—directly or through one or more companies—shares issued by a Peruvian company, and the following two conditions are concurrently met:

 

(i) during any of the 12 months preceding the transfer, the fair market value (“FMV”) of the shares issued by the Peruvian company held directly or indirectly by the nonresident company which shares are being sold, is equivalent to 50% or more of the FMV of all the shares issued by said non-resident company; and

 

(ii) during any 12-month period, the shares transferred by a party, including those transferred by its related parties, represent at least 10% of the shares issued by such non-resident company.

 

Due to recent modifications to Peruvian income tax law, as of January 1, 2019, even if the abovementioned conditions are not met, an indirect transfer of Peruvian shares will also be deemed to exist if the “total value” of shares of the Peruvian company indirectly transferred within any 12-month period is equivalent to or higher than 40,000 Peruvian tax units (S/176 million or US$50.0 million approximately). Said “total value” is determined by multiplying: i) the “percentage” that the FMV of the shares issued by the Peruvian company held (directly or indirectly) by the non-resident company which shares are being transferred, represents with regard to the FMV of all the shares issued by said non-resident company; and, ii) the price agreed for the shares issued by the non-resident company directly transferred. To determine the “total value” threshold, transfers made by those parties which qualify as related to the transferor should also be considered. Nonetheless, the “taxable base” shall be determined, in any case, per party, considering the transfers made by the latter within the abovementioned 12-month period, but excluding those transfers previously taxed.

 

In case the sale of the shares were to qualify as an “indirect transfer of Peruvian shares” (and the transfer of the beneficial interest on the shares were to be considered as an actual transfer of such shares), any capital gain resulting therefrom will be subject to a 30% tax rate in Peru.

 

In case the corporate investor that makes the indirect transfer of Peruvian shares has a branch or a permanent establishment with assigned assets in Peru, said corporation will be jointly and severally liable for any income tax that resulted from the transfer of Peruvian shares; it will also be obligated to present to the Peruvian tax authority all the information related to the Peruvian shares of the non-resident investor that are being sold, particularly the information referred to the FMV; participation percentages; capital increase or reduction; issuance and placement of shares or participations; reorganization processes; patrimonial values and balance sheets; etc. Investors should consult their own tax advisors about the consequences of the acquisition, ownership, and disposition of their investment in the offered shares or any beneficial interest therein, including the possibility that the tax consequences of investing in the offered shares may differ from the description above.

 

United States federal income tax considerations

 

The following is a summary of certain U.S. federal income tax considerations that are likely to be relevant to the purchase, ownership and disposition of our common shares by a U.S. Holder (as defined below).

 

This summary is based on provisions of the Internal Revenue Code of 1986, as amended (the “Code”), and U.S. Treasury regulations (Regulations), rulings and judicial interpretations thereof, in force as of the date hereof, and the U.S.-Luxembourg Treaty dated December 20, 2000 (as amended by any subsequent protocols). Those authorities may be changed at any time, perhaps retroactively, so as to result in U.S. federal income tax consequences different from those summarized below.

 

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Taxation

 

This summary is not a comprehensive discussion of all of the tax considerations that may be relevant to a particular investor’s decision to purchase, hold, or dispose of our common shares. In particular, this summary is directed only to U.S. Holders that hold common shares as capital assets and does not address tax consequences to U.S. Holders who may be subject to special tax rules, such as banks, brokers or dealers in securities or currencies, traders in securities electing to mark to market, financial institutions, life insurance companies, tax exempt entities, entities that are treated as partnerships for U.S. federal income tax purposes (or partners therein), holders that own or are treated as owning 10% or more of our common shares by vote or value, persons holding common shares as part of a hedging or conversion transaction or a straddle, nonresident alien individuals present in the United States for more than 182 days in a taxable year, or persons whose functional currency is not the U.S. dollar. Moreover, this summary does not address state, local or foreign taxes, U.S. federal estate and gift taxes, or the Medicare contribution tax applicable to net investment income of certain non-corporate U.S. Holders, or the alternative minimum tax consequences of acquiring, holding or disposing of common shares.

 

For purposes of this summary, a “U.S. Holder” is a beneficial owner of common shares that is a citizen or resident of the United States, a U.S. domestic corporation or that otherwise is subject to U.S. federal income taxation on a net income basis in respect of such common shares.

 

U.S. Holders should consult their tax advisors about the consequences of the acquisition, ownership, and disposition of the common shares, including the relevance to their particular situation of the considerations discussed below and any consequences arising under foreign, state, local or other tax laws.

 

Taxation of dividends

 

Subject to the discussion below under “Passive Foreign Investment Company Status” the gross amount of any distribution of cash or property with respect to our common shares that is paid out of our current or accumulated earnings and profits (as determined for U.S. federal income tax purposes) will generally be includible in a U.S. Holder’s taxable income as ordinary dividend income on the day on which the U.S. Holder receives the dividend and will not be eligible for the dividends received deduction allowed to corporations under the Code.

 

We do not expect to maintain calculations of our earnings and profits in accordance with U.S. federal income tax principles. U.S. Holders therefore should expect that distributions generally will be treated as dividends for U.S. federal income tax purposes.

 

Subject to certain exceptions for short-term positions, dividends received by an individual with respect to the common shares will be subject to taxation at a preferential rate if the dividends are “qualified dividends.” Dividends paid on the common shares will be treated as qualified dividends if:

 

· the common shares are readily tradable on an established securities market in the United States; and

 

· we were not, in the year prior to the year in which the dividend was paid, and are not, in the year in which the dividend is paid, a passive foreign investment company (“PFIC”).

 

The common shares are listed on the NYSE and will qualify as readily tradable on an established securities market in the United States so long as they are so listed. Based on our consolidated financial statements and relevant market and shareholder data, we believe that we were not classified as a PFIC with respect to our prior taxable year. In addition, based on our consolidated financial statements and our current expectations regarding the value and nature of our assets, the sources and nature of our income and relevant market and shareholder data, we do not anticipate becoming a PFIC for our current taxable year or in the foreseeable future. Accordingly, we expect that dividends paid on the common shares will be treated as qualified dividends. U.S. Holders should consult their tax advisors regarding the availability of the reduced dividend tax rate in light of their own particular circumstances.

 

Dividend distributions with respect to our common shares generally will be treated as “passive category” income from sources outside the United States for purposes of determining a U.S. Holder’s U.S. foreign tax credit limitation. Subject to the limitations and conditions provided in the Code and the applicable Regulations, a U.S. Holder may be able to claim a foreign tax credit against its U.S. federal income tax liability in respect of any Luxembourg income taxes withheld at the appropriate rate applicable to the U.S. Holder from a dividend paid to such U.S. Holder. Alternatively, the U.S. Holder may deduct such Luxembourg income taxes from its U.S. federal taxable income, provided that the U.S. Holder elects to deduct rather than credit all foreign income taxes for the relevant taxable year. The rules with respect to foreign tax credits are complex and involve the application of rules that depend on a U.S. Holder’s particular circumstances. Accordingly, U.S. Holders are urged to consult their tax advisors regarding the availability of the foreign tax credit under their particular circumstances.

 

U.S. Holders that receive distributions of additional common shares or rights to subscribe for common shares as part of a pro rata distribution to all our shareholders generally will not be subject to U.S. federal income tax in respect of the distributions.

 

172

 

 

Taxation

 

Taxation of dispositions of common shares

 

Subject to the discussion below under “—Passive Foreign Investment Company Status,” a U.S. Holder generally will recognize gain or loss on the sale, exchange or other disposition of common shares in an amount equal to the difference, if any, between the amount realized upon the sale, exchange or other disposition and the U.S. Holder’s adjusted tax basis in the common shares. A U.S. Holder’s adjusted tax basis in its common shares generally will equal the purchase price for the common shares. Any gain or loss will be capital gain or loss and generally will be long-term capital gain or loss if the common shares have been held for more than one year. Long-term capital gain realized by a U.S. Holder that is an individual generally is subject to taxation at a preferential rate. The deductibility of capital losses is subject to limitations. Gain, if any, realized by a U.S. Holder on the sale or other disposition of the common shares generally will be treated as U.S. source income for U.S. foreign tax credit purposes.

 

Passive foreign investment company status

 

Special U.S. tax rules apply to companies that are considered to be PFICs. We will be classified as a PFIC in a particular taxable year if either:

 

· 75 percent or more of our gross income for the taxable year is passive income; or

 

· the average percentage of the value of our assets that produce or are held for the production of passive income is at least 50 percent.

 

Passive income generally includes dividends, interest, royalties, rents, annuities, net gains from the sale or exchange of property producing such income, net foreign currency gains, and gains from commodities transactions other than gains that are active business gains from the sale of commodities or arise from “commodity hedging transactions”, within the meaning of the applicable rules (“Commodity Exception”).

 

Based on certain estimates of our gross income and gross assets and relying on the Commodity Exception, we do not believe that we currently are a PFIC, and do not anticipate becoming a PFIC in the foreseeable future. However, since PFIC status will be determined by us on an annual basis and since such status depends upon the composition of our income and assets, and the nature of our activities (including our ability to qualify for the Commodity Exception or any similar exceptions), from time to time, there can be no assurance that we will not be considered a PFIC for any taxable year. In the event that, contrary to our expectation, we are classified as a PFIC in any year, and a U.S. Holder does not make a mark-to-market election, as described in the following paragraph, the U.S. Holder will be subject to a special tax at ordinary income tax rates on “excess distributions,” including certain distributions by us and gain that the U.S. Holder recognizes on the sale of the common shares. The amount of income tax on any excess distributions will be increased by an interest charge to compensate for tax deferral, calculated as if the excess distributions were earned ratably over the period that the U.S. Holder holds the common shares. Classification as a PFIC may also have other adverse tax consequences.

 

A U.S. Holder can avoid the unfavorable rules described in the preceding paragraph by electing to mark the common shares to market. If a U.S. Holder makes this mark-to-market election, the U.S. Holder will be required in any year in which we are a PFIC to include as ordinary income the excess of the fair market value of the U.S. Holder’s common shares at year-end over the U.S. Holder’s basis in those shares. The U.S. Holder’s basis in the shares will be adjusted to reflect the gain or loss. In addition, any gain that the U.S. Holder recognizes upon the sale of the common shares will be taxed as ordinary income in the year of sale.

 

A U.S. Holder that owns an equity interest in a PFIC must annually file IRS Form 8621 and may be required to file other IRS forms. A failure to file one or more of these forms as required may toll the running of the statute of limitations in respect of each of the U.S. Holder’s taxable years for which such form is required to be filed. As a result, the taxable years with respect to which the U.S. Holder fails to file the form may remain open to assessment by the U.S. Internal Revenue Service (“IRS”) indefinitely, until the form is filed.

 

U.S. Holders should consult their tax advisors regarding the U.S. federal income tax considerations discussed above and the desirability of making a mark-to-market election if we were to be classified as a PFIC.

 

173

 

 

Taxation

 

Foreign financial asset reporting

 

Certain U.S. Holders that own “specified foreign financial assets” with an aggregate value in excess of US$50,000 on the last day of the taxable year or US$75,000 at any time during the taxable year are generally required to file an information statement along with their tax returns, currently on Form 8938, with respect to such assets. “Specified foreign financial assets” include any financial accounts held at a non-U.S. financial institution, as well as securities issued by a non-U.S. issuer that are not held in accounts maintained by financial institutions. The understatement of income attributable to “specified foreign financial assets” in excess of US$5,000 extends the statute of limitations with respect to the tax return to six years after the return was filed. U.S. Holders who fail to report the required information could be subject to substantial penalties. Prospective investors are encouraged to consult with their tax advisors regarding the possible application of these rules, including the application of the rules to their particular circumstances.

 

Backup withholding and information reporting

 

Dividends paid on, and proceeds from the sale or other disposition of, the common shares to a U.S. Holder generally may be subject to the information reporting requirements of the Code and may be subject to backup withholding unless the U.S. Holder provides an accurate taxpayer identification number and makes any other required certification or otherwise establishes an exemption. Backup withholding is not an additional tax. The amount of any backup withholding from a payment to a U.S. Holder will be allowed as a refund or credit against the U.S. Holder’s U.S. federal income tax liability, provided the required information is furnished to the IRS in a timely manner.

 

A holder that is a foreign corporation or a non-resident alien individual may be required to comply with certification and identification procedures in order to establish its exemption from information reporting and backup withholding.

 

174

 

 

Exchange Controls and Other Limitations Affecting Security Holders

 

Exchange controls and other limitations affecting security holders

 

We are not aware of any governmental laws, decrees, regulations or other legislation in Luxembourg that restrict the export or import of capital, including the availability of cash and cash equivalents for use by our affiliated companies, or that affect the remittance of dividends, interest or other payments to non-resident holders of our securities.

 

175

 

 

Evaluation of Disclosure Controls and Procedures

 

Evaluation of disclosure controls and procedures

 

Our management, with the participation of our chief executive officer and chief financial officer, has evaluated the effectiveness of our disclosure controls and procedures as of December 31, 2020. There are inherent limitations to the effectiveness of any system of disclosure controls and procedures, including the possibility of human error and the circumvention or overriding of the controls and procedures. Accordingly, even effective disclosure controls and procedures can only provide reasonable assurance of achieving their control objectives.

 

We have evaluated, with the participation of our chief executive officer and chief financial officer, the effectiveness of our disclosure controls and procedures as of December 31, 2020. Based on our evaluation, our chief executive officer and chief financial officer concluded that our disclosure controls and procedures were effective as of December 31, 2020.

 

176

 

 

Internal Control Over Financial Reporting

 

Internal control over financial reporting

 

Management report on internal control over financial reporting

 

Our management is responsible for establishing and maintaining adequate internal control over financial reporting and for assessing its effectiveness.

 

Our internal control over financial reporting is a process designed by, or under the supervision of, our chief executive officer and our chief financial officer, and effected by our board of directors, management and other employees, and is designed to provide reasonable assurance regarding the reliability of financial reporting and of the preparation of our consolidated financial statements, in accordance with IFRS as issued by the IASB.

 

Due to its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness of internal control over financial reporting to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with our policies or procedures may deteriorate.

 

Our management has assessed the effectiveness of our internal control over financial reporting as of December 31, 2020, based upon the criteria established in Internal Controls—Integrated Framework (2013), issued by the Committee of Sponsoring Organizations of Treadway Commission (“COSO”). Based on this assessment and criteria, our management has concluded that our internal control over financial reporting was effective as of December 31, 2020.

 

Audit of the effectiveness of internal control over financial reporting

 

Our independent registered public accounting firm, PricewaterhouseCoopers Auditores Independentes, has audited the effectiveness of our internal control over financial reporting, as stated in its report as of December 31, 2020, which is included herein.

 

Changes in internal control over financial reporting

 

There were no changes in our internal control over financial reporting during the fiscal year of 2020, which have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

 

177

 

 

Principal Accountant Fees and Services

 

Principal accountant fees and services

 

The following table summarizes the fees billed to us by our independent auditors PricewaterhouseCoopers Auditores Independentes for professional services in 2020 and 2019:

 

    For the Year Ended December 31,  
    2020     2019  
             
    (US$ thousand)  
Audit fees     1,762.4       1,639.1  
Audit-related fees     543.9       24.9  
Tax fees     -       51.3  
Other fees     17.5       18.0  
Total fees     2,323.9       1,733.3  

 

“Audit fees” are the aggregate fees billed by PricewaterhouseCoopers Auditores Independentes for the audit of our annual financial statements, the audit of the statutory financial statements of our subsidiaries, and reviews of interim financial statements and attestation services that are provided in connection with statutory and regulatory filings or engagements. They also include fees for services that only the independent auditor reasonably can provide, including the provision of comfort letters and consents in connection with statutory and regulatory filings and the review of documents filed with the SEC and other capital markets or local financial reporting regulatory bodies. “Audit-related fees” are fees charged by PricewaterhouseCoopers Auditores Independentes for assurance and related services that are reasonably related to the performance of the audit or review of our consolidated financial statements and are not reported under “Audit fees.” “Tax fees” are the aggregate fees billed by PriceWaterhouseCoopers Auditores Independentes for services rendered for tax compliance, tax advice and tax planning. “Other fees” are the aggregate fees billed by PricewaterhouseCoopers Auditores Independentes for services related with assurance and review procedures not related with regulatory or financial reporting of our consolidated financial statements.

 

Nexa has established policies and procedures that require any engagement of our independent auditor for audit or non-audit services to be submitted to and pre-approved by the audit committee. In addition, our audit committee may delegate the authority to pre-approve non-audit services to one or more of its members. All non-audit services that are pre-approved pursuant to such delegated authority must be presented to the full audit committee at its first scheduled meeting following such pre-approval. Our audit committee also has the authority to recommend pre-approval policies and procedures to our board of directors and for the engagement of our independent auditor’s services.

 

178

 

 

Information Filed with Securities Regulators

 

Information filed with securities regulators

 

We are subject to various information and disclosure requirements in those countries in which our securities are traded, and we file financial statements and other periodic reports with the SEC and Canadian securities regulatory authorities.

 

· United States. We are subject to the information requirements of the Securities Exchange Act of 1934, as amended, and accordingly file reports and other information with the SEC. Our SEC filings are available to the public from the SEC at http://www.sec.gov. You may also inspect Nexa Resources’ reports and other information at the offices of the New York Stock Exchange, 11 Wall Street, New York, New York 10005, on which our common shares are listed. For further information on obtaining copies of Nexa Resources’ public filings at the NYSE, you should call (212) 656-5060.

 

· Canada. We must comply with certain Canadian periodic and ongoing disclosure rules under applicable Canadian provincial and territorial securities laws and, as applicable, the rules of the Toronto Stock Exchange. However, with respect to the rules under applicable Canadian provincial and territorial securities laws, we are able to rely on certain exemptions from many of the requirements under such laws through our compliance with U.S. disclosures given our status in the U.S as a foreign private issuer. We may also be able to rely on certain exemptions under the rules of the TSX. Our Canadian filings are available to the public from the website maintained by the Canadian Securities Administrators at www.sedar.com.

 

179

 

 

Glossary

 

Glossary

 

Brownfields project: An exploration or development project near or within an existing operation, which can share infrastructure and management.

 

Concentration: The process by which crushed and ground ore is separated into metal concentrates and reject material through processes such as flotation.

 

Concentrate plant: A plant where metal concentration occurs.

 

Cut-off grade: is the grade (i.e., the concentration of metal or mineral in rock) that determines the destination of the material during mining.

 

Development: The process of constructing a mining facility and the infrastructure to support the facility is known as mine development.

 

Diamond drilling: A method of drilling that uses a diamond bit, which rotates at the end of a drill rod or pipe. The opening at the end of the diamond bit allows a solid column of rock to move up into the drill pipe and be recovered at the surface. This column of rock is named drill core and is used for geological, geotechnical logging and for sampling for chemical analysis to define the metal content of the rock or mineralized material. Standard core sizes/diameters are 63.5 mm (defined as HQ), 46.7 mm (defined as NQ) and 36.5 mm (defined as BQ). Most drill rods are 10 feet long. After the first 10 feet are drilled, a new section of pipe is screwed into the top end, so the combination of pipes can be driven another 10 feet into the ground.

 

Exploration: Activities associated with ascertaining the existence, location, extent or quality of a mineral deposit.

 

Exploration stage property: is a property that has no mineral reserves disclosed.

 

Greenfields project: An exploration or development projects that is located outside the area of influence of existing mine operations and/or infrastructure and will be independently developed and managed.

 

Indicated Mineral Resource: is that part of a mineral resource for which quantity and grade or quality are estimated on the basis of adequate geological evidence and sampling.

 

Inferred Mineral Resource: is that part of a mineral resource for which quantity and grade or quality are estimated on the basis of limited geological evidence and sampling.

 

km: kilometer.

 

ktpd: thousand tonnes per day.

 

LBMA: The London Bullion Market Association.

 

LME: London Metal Exchange.

 

LOM: life of mine.

 

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Glossary

 

Measured Mineral Resource: is that part of a mineral resource for which quantity and grade or quality are estimated on the basis of conclusive geological evidence and sampling.

 

Metal concentrate: The crushed and ground material obtained after concentration, including zinc, lead and copper concentrates. This is the product from our mining operations. Most of the zinc concentrate we produce is used in our smelting operations and the remaining portion, along with our lead and copper concentrates, is sold to our customers.

 

Metallic zinc: Pure metal (99.995% zinc) obtained from the electrodeposition of a zinc sulfate solution, free of impurities, through the Roaster-Leaching-Electrolysis (“RLE”) process.

 

Mineralization: The process or processes by which a mineral or minerals are introduced into a rock, resulting in a potentially valuable or valuable deposit.

 

Mineralized material: Mineral bearing material that has been physically delineated by one or more methods, including drilling and underground work, and is supported by sampling and chemical analysis. This material has been found to contain a sufficient amount of mineralization of an average grade of metal or metals to have economic potential that warrants further exploration evaluation. While this material is not currently or may never be classified as ore reserves, it is reported as mineralized material only if the potential exists for reclassification into the reserves category. This material cannot be classified in the reserves category until final technical, economic and legal factors have been determined. Under the SEC’s standards, a mineral deposit does not qualify as a reserve unless it can be economically and legally extracted at the time of reserve determination and it constitutes a proven or probable reserve (as defined below).

 

Mineral Reserve: is an estimate of tonnage and grade or quality of indicated and measured mineral resources that, in the opinion of the qualified person, can be the basis of an economically viable project. More specifically, it is the economically mineable part of a measured or indicated mineral resource, which includes diluting materials and allowances for losses that may occur when the material is mined or extracted.

 

Mineral Resource: is a concentration or occurrence of material of economic interest in or on the Earth's crust in such form, grade or quality, and quantity that there are reasonable prospects for economic extraction. A mineral resource is a reasonable estimate of mineralization, taking into account relevant factors such as cut-off grade, likely mining dimensions, location or continuity that, with the assumed and justifiable technical and economic conditions, is likely to, in whole or in part, become economically extractable.

 

Mine site: An economic unit comprised of an underground and/or open pit mine, a treatment plant and equipment and other facilities necessary to produce metals concentrates, in existence at a certain location.

 

NSR: Net Smelter Return is the net revenue that the owner of a mining property receives from the sale of the mine’s metal/nonmetal products less transportation and refining costs.

 

Open pit: Surface mining in which the ore is extracted from a pit. The geometry of the pit may vary with the characteristics of the ore body.

 

Ore: A mineral or aggregate of minerals from which metal can be economically mined or extracted.

 

Ore grade: The average amount of metal expressed as a percentage, grams per tonne or in ounces per tonne.

 

Ounces or oz: Unit of weight. A troy ounce equals 31.1034 grams. All references to ounces in this report are to troy ounces unless otherwise specified.

 

Probable Mineral Reserve: is the economically mineable part of an indicated and, in some cases, a measured mineral resource.

 

Production stage property: is a property with material extraction of mineral reserves.

 

Proven Mineral Reserve: is the economically mineable part of a measured mineral resource and can only result from conversion of a measured mineral resource.

 

181

 

 

Glossary

 

Reclamation: The process of stabilizing, contouring, maintaining, conditioning and/or reconstructing the surface of disturbed land (i.e., used or affected by the execution of mining activities) to a state of “equivalent land capability.” Reclamation standards vary widely, but usually address issues of ground and surface water, topsoil, final slope gradients, overburden and revegetation.

 

Refining: The process of purifying an impure metal; the purification of crude metallic substances.

 

Secondary feed materials: By-products of industrial processes such as smelting and refining that are then available for further treatment/recycling. It can cover foundry ashes, zinc oxides from brass and bronze production, electric arc furnace (“EAF”) dust and slags.

 

SHG: Special High Grade.

 

Skarn: Metamorphic zone developed in the contact area around igneous rock intrusions when carbonate sedimentary rocks are invaded by large amounts of silicon, aluminum, iron and magnesium. The minerals commonly present in a skarn include iron oxides, calc-silicates, andradite and grossularite garnet, epidote and calcite. Many skarns also include ore minerals. Several productive deposits of copper or other base metals have been found in and adjacent to skarns.

 

Tailings: Finely ground rock from which valuable minerals have been extracted by concentration.

 

Tonne: A unit of weight. One metric tonne equals 2,204.6 pounds or 1,000 kilograms. One short tonne equals 2,000 pounds. Unless otherwise specified, all references to “tonnes” in this report refer to metric tonnes.

 

Zinc equivalent: A metric used to compare mineralization that is comprised of different metals in terms of zinc. Copper, lead, silver and gold contents in our concentrate production have been converted to a zinc equivalent grade at the average benchmark prices for 2019, i.e., US$2,546.34 per tonne (US¢115.50 per pound) for zinc, US$5,999.73 per tonne (US¢272.14 per pound) for copper, US$1,999.68 per tonne (US¢90.70 per pound) for lead, US$16.21 per ounce for silver and US$1,392.60 per ounce for gold.

 

Zinc oxide: A chemical compound that results from the sublimation of zinc (Zn-metal) by oxygen in the atmosphere. Zinc oxide is in the form of powder or fine grains that is insoluble in water but very soluble in acid solutions.

 

182

 

 

Exhibits

 

Exhibits

 

Exhibit Number

 
1 Amended and Consolidated Articles of Association of Nexa Resources S.A., dated as of June 4, 2020.
2.1 Indenture with respect to the 6.500% Notes due 2028, dated June 18, 2020, among Nexa Resource S.A., as issuer, Nexa Resources Cajamarquilla S.A., Nexa Resources Peru S.A. and Nexa Recursos Minerais S.A., as guarantors, and The Bank of New York Mellon, as trustee, registrar, paying agent and transfer agent.
2.2 Indenture with respect to the 5.375% Notes due 2027, dated as of May 4, 2017, among VM Holding S.A., as issuer, Votorantim Metais Zinco S.A., Compañía Minera Milpo S.A.A. and Votorantim Metais Cajamarquilla S.A., as guarantors, and The Bank of New York Mellon, as trustee, registrar, paying agent and transfer agent (incorporated by reference to Exhibit 4.1 to our Registration Statement on Form F-1 (file no. 333-220552) filed with the SEC on September 21, 2017).
2.3 Indenture with respect to the 4.625% Notes due 2023, dated as of March 28, 2013, among Compañía Minera Milpo S.A.A., as issuer, Deutsche Bank Trust Company Americas, as trustee, registrar, paying agent and transfer agent, and Deutsche Bank Luxembourg S.A., as Luxembourg paying agent (incorporated by reference to Exhibit 4.2 to our Registration Statement on Form F-1 (file no. 333-220552) filed with the SEC on September 21, 2017).
2.4 Description of Securities.
8 List of Subsidiaries.
12.1 Certification of Chief Executive Officer of Nexa Resources S.A. pursuant to Rules 13a-14 and 15d-14 under the Securities Exchange Act of 1934, as amended.
12.2 Certification of Chief Financial Officer of Nexa Resources S.A. pursuant to Rules 13a-14 and 15d-14 under the Securities Exchange Act of 1934, as amended.
13.1 Certification of Chief Executive Officer and Chief Financial Officer of Nexa Resources S.A., pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.
15.1 Technical Report Summary on the Cerro Lindo Mine, Department of Ica, Peru – S-K 1300 Report.
15.2 Technical Report Summary on the El Porvenir Polymetallic Operations, Department of Pasco, Peru – S-K 1300 Report.
15.3 Technical Report Summary on the Vazante Polymetallic Operations, Minas Gerais, Brazil – S-K 1300 Report.
15.4 Technical Report Summary on the Aripuanã Zinc Project, State of Mato Grosso, Brazil – S-K 1300 Report (incorporated by reference to Exhibit 99.1 to our Current Report on Form 6-K filed with the SEC on March 22, 2021).
15.5 Consent of SLR Consulting (Canada) Ltd. (“SLR”) with respect to Technical Report Summary of Cerro Lindo Mine (included in Exhibit 15.1)
15.6 Consent of SLR Consulting (Canada) Ltd. (“SLR”) with respect to Technical Report Summary of El Porvenir Polymetallic Operations (included in Exhibit 15.2)
15.7 Consent of SLR Consulting (Canada) Ltd. (“SLR”) with respect to Technical Report Summary of Vazante Polymetallic Operations (included in Exhibit 15.3)
15.8 Consent of SLR Consulting (Canada) Ltd. (“SLR”) with respect to Technical Report Summary of Aripuanã Zinc Project (incorporated by reference to Exhibit 99.2 to our Current Report on Form 6-K filed with the SEC on March 22, 2021).
15.9 Consent letter of Nexa’s Qualified Person
101.INS XBRL Instance Document
101.SCH XBRL Taxonomy Extension Schema Document
101.CAL XBRL Taxonomy Extension Calculation Linkbase Document
101.DEF XBRL Taxonomy Extension Definition Linkbase Document
101.LAB XBRL Taxonomy Extension Label Linkbase Document
101.PRE XBRL Taxonomy Extension Presentation Linkbase Document

 

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Signatures

 

Signatures

 

The registrant hereby certifies that it meets all of the requirements for filing on Form 20-F and that it has duly caused and authorized the undersigned to sign this annual report on its behalf.

 

NEXA RESOURCES S.A.

 

By: /s/ Tito Botelho Martins Júnior  
    Name: Tito Botelho Martins Júnior  
    Title: President and Chief Executive Officer  

 

By: /s/ Rodrigo Menck  
    Name: Rodrigo Menck
    Title: Senior Vice President Finance and Group Chief Financial Officer  

 

Date: March 22, 2021

 

  184  

 

  

 

  Nexa Resources S.A.
  Consolidated financial statements 
  at December 31, 2020 and independent auditor’s report

 

 

 

 

 

Contents

 

Consolidated financial statements

Consolidated income statement 3
Consolidated statement of comprehensive income 4
Consolidated balance sheet 5
Consolidated statement of cash flows 6
Consolidated statement of changes in shareholders’ equity 7

 

Notes to the consolidated financial statements

1 General information 9
2 Information by business segment 10
3 Basis of preparation of the consolidated financial statements 12
4 Principles of consolidation 18
5 Changes in the main accounting policies and disclosures 20
6 Net revenues 21
7 Expenses by nature 24
8 Mineral exploration and project evaluation 24
9 Other income and expenses, net 25
10 Net financial results 25
11 Current and deferred income tax 26
12 Financial risk management 29
13 Financial instruments 34
14 Fair value estimates 36
15 Cash and cash equivalents 38
16 Financial investments 39
17 Derivative financial instruments 39
18 Sensitivity analysis 42
19 Trade accounts receivables 43
20 Inventory 44
21 Other assets 45
22 Related parties 46
23 Property, plant and equipment 48
24 Intangible assets 53
25 Right-of-use assets and lease liabilities 55
26 Loans and financings 56
27 Trade Payables 60
28 Asset retirement and environmental obligations 61
29 Provisions 62
30 Contractual obligations 65
31 Confirming Payables 66
32 Shareholders’ equity 67
33 Impairment of non-current assets 70
34 Long-term commitments 76
35 Events after the reporting period 76

 

 

 

 

Nexa Resources S.A.

 

Consolidated income statement 

Years ended December 31 

All amounts in thousands of US dollars, unless otherwise stated

 

 

 

    Note   2020     2019     2018  
Net revenues     6     1,950,929       2,332,715       2,491,670  
Cost of sales     7   (1,563,931 )   (1,947,828 )   (1,892,247 )
Gross profit           386,998       384,887       599,423  
                               
Operating expenses                              
Selling, general and administrative     7     (151,619 )     (216,511 )     (159,603 )
Mineral exploration and project evaluation     7 and 8     (57,201 )     (119,063 )     (129,559 )
Impairment of non-current assets     33     (557,497 )     (142,133 )     (3,283 )
Other income and expenses, net     9     (19,164 )     (18,206 )     27,575  
            (785,481 )     (495,913 )     (264,870 )
Operating (loss) income           (398,483 )     (111,026 )     334,553  
                               
Net financial results     10                        
Financial income           11,168       31,054       67,509  
Financial expenses           (159,759 )     (117,399 )     (119,124 )
Other financial items, net           (129,584 )     (18,509 )     (151,039 )
            (278,175 )     (104,854 )     (202,654 )
                               
(Loss) income before income tax           (676,658 )     (215,880 )     131,899  
                               
Income tax     11 (a)                        
Current           (63,192 )     (46,382 )     (71,787 )
Deferred           87,344       104,746       33,030  
Net (loss) income for the year           (652,506 )     (157,516 )     93,142  
Attributable to NEXA's shareholders           (559,247 )     (145,135 )     77,026  
Attributable to non-controlling interests           (93,259 )     (12,381 )     16,116  
Net (Loss) income for the year           (652,506 )     (157,516 )     93,142  
Weighted average number of outstanding shares – in thousands           132,439       132,622       133,313  
Basic and diluted (losses) earnings per share – USD     32 (f)     (4.22 )     (1.09 )     0.58  

 

The accompanying notes are an integral part of these consolidated financial statements

 

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Nexa Resources S.A.

 

Consolidated statement of comprehensive income 

Years ended December 31 

All amounts in thousands of US dollars, unless otherwise stated

 

 

 

    Note   2020     2019     2018  
Net (loss) income for the year         (652,506 )     (157,516 )     93,142  
                             
Other comprehensive loss, net of income tax - items that can be reclassified to the income statement                            
Cash flow hedge accounting   17 (b)     (98 )     1,332       (2,318 )
Deferred income tax         101       (453 )     126  
Translation adjustment of foreign subsidiaries   32 (e)     (138,840 )     (21,115 )     (9,959 )
          (138,837 )     (20,236 )     (12,151 )
                             
Other comprehensive loss, net of income tax - items that will not be reclassified to the income statement                            
Changes in fair value of financial liabilities that relate to changes in the Company’s own credit risk   26 (c)     (787 )     -       -  
Deferred income tax         (88 )     -       -  
          (875 )     -       -  
Other comprehensive loss for the year, net of income tax         (139,712 )     (20,236 )     (12,151 )
                             
Total comprehensive (loss) income for the year         (792,218 )     (177,752 )     80,991  
Attributable to NEXA’s shareholders         (682,132 )     (172,453 )     75,094  
Attributable to non-controlling interests         (110,086 )     (5,299 )     5,897  
Total comprehensive (loss) income for the year         (792,218 )     (177,752 )     80,991  

 

The accompanying notes are an integral part of these consolidated financial statements

 

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Nexa Resources S.A.

 

Consolidated balance sheet

As at December 31

All amounts in thousands of US dollars, unless otherwise stated

 
 

 

Assets   Note     2020     2019  
Current assets                  
Cash and cash equivalents     15       1,086,163       698,618  
Financial investments     16       35,044       58,423  
Derivative financial instruments     17       16,329       4,835  
Trade accounts receivables     19       229,032       177,231  
Inventory     20       256,522       295,258  
Recoverable income tax             12,953       37,850  
Other assets     21       91,141       103,134  
              1,727,184       1,375,349  
Non-current assets                        
Financial investments     16       -       352  
Derivative financial instruments     17       15,651       14,689  
Deferred income tax     11       221,580       239,740  
Recoverable income tax             13,110       6,663  
Other assets     21       93,131       138,808  
Property, plant and equipment     23       1,898,296       2,122,690  
Intangible assets     24       1,076,405       1,538,526  
Right-of-use assets     25       18,869       29,547  
              3,337,042       4,091,015  
                         
Total assets             5,064,226       5,466,364  
                         
Liabilities and shareholders’ equity                        
Current liabilities                        
Loans and financings     26       146,002       33,149  
Lease liabilities     25       15,999       16,474  
Derivative financial instruments     17       5,390       8,276  
Trade payables     27       370,122       414,080  
Confirming payables     31       145,295       82,770  
Dividends payable             4,557       6,662  
Asset retirement and environmental obligations     28       33,095       19,001  
Contractual obligations     30       27,132       26,351  
Salaries and payroll charges             56,107       58,913  
Tax liabilities             43,630       9,694  
Other liabilities             29,230       23,620  
              876,559       698,990  
Non-current liabilities                        
Loans and financings     26       1,878,312       1,475,408  
Lease liabilities     25       9,690       17,910  
Derivative financial instruments     17       21,484       13,542  
Asset retirement and environmental obligations     28       242,951       274,826  
Provisions     29       30,896       26,071  
Deferred income tax     11       218,392       287,952  
Contractual obligations     30       138,893       154,171  
Other liabilities             25,805       35,308  
              2,566,423       2,285,188  
                         
Total liabilities             3,442,982       2,984,178  
                         
Shareholders’ equity     32                  
Attributable to NEXA’s shareholders             1,377,445       2,109,577  
Attributable to non-controlling interests             243,799       372,609  
              1,621,244       2,482,186  
Total liabilities and shareholders’ equity               5,064,226       5,466,364  

 

The accompanying notes are an integral part of these consolidated financial statements

 

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Nexa Resources S.A.

 

Consolidated statement of cash flows

Years ended December 31

All amounts in thousands of US dollars, unless otherwise stated

 
 

 

    Note   2020     2019     2018  
Cash flows from operating activities                            
(Loss) income before income tax         (676,658 )     (215,880 )     131,899  
Impairment of non-current assets   33     557,497       142,133       3,283  
Depreciation and amortization   23, 24 and 25     243,925       317,892       267,189  
Interest and foreign exchange effects         157,806       65,000       143,199  
Loss (gain) on sale of property, plant and equipment and intangible assets   9     2,268       (857 )     8,616  
Gain on sale of investments   9     -       -       (348 )
Changes in provisions         13,159       3,854       29,777  
Changes in Fair Value of loans and financings   10     8,058       6,640       -  
Changes in operating assets and liabilities   15 (b)     92,460       (71,634 )     (53,040 )
Interest paid on loans and financings   26 (c)     (69,906 )     (71,804 )     (74,592 )
Interest paid on lease liabilities   25 (b)     (1,385 )     (3,259 )     -  
Premium paid on bonds repurchase   26 (c)     (14,481 )     -       -  
Income tax paid         (21,043 )     (49,262 )     (108,385 )
Net cash provided by operating activities         291,700       122,823       347,598  
                             
Cash flows from investing activities                            
Additions of property, plant and equipment   23     (323,688 )     (396,672 )     (299,773 )
Net (purchases) sales of financial investments         (47,522 )     54,710       140,402  
Proceeds from the sale of property, plant and equipment         2,014       6,570       1,268  
Net cash used in by investing activities         (369,196 )     (335,392 )     (158,103 )
                             
Cash flows from financing activities                            
New loans and financings   26 (c)     1,296,496       106,229       294,640  
Debt issue costs   26 (c)     (9,921 )     (255 )     (1,739 )
Payments of loans and financings   26 (c)     (757,513 )     (19,437 )     (295,104 )
Payments of lease liabilities   25 (b)     (9,100 )     (13,280 )     -  
Dividends paid   32 (j)     (55,964 )     (113,389 )     (3,475 )
Dividends not withdrawn         1,009       -       -  
Reimbursement of share premium         -       -       (80,000 )
Repurchase of the Company’s own shares         -       (8,103 )     (1,352 )
Acquisition of non-controlling interests         -       (71,054 )     -  
Capital reduction related to Pollarix S.A. acquisition         -       -       (87,623 )
Capital reduction of subsidiary – non-controlling interests   32 (i)     (13,392 )     -       -  
Disbursement from equity transactions with non-controlling shareholders         -       -       (2,757 )
Net cash (used in) provided by financing activities         451,615       (119,289 )     (177,410 )
                             
Foreign exchange effects on cash and cash equivalents         (16,070 )     (2,462 )     1,816  
Other highly liquid short-term investments   15     29,496       -       -  
                             
(Decrease) increase in cash and cash equivalents         387,545       (334,320 )     13,901  
Cash and cash equivalents at the beginning of the year         698,618       1,032,938       1,019,037  
Cash and cash equivalents at the end of the year         1,086,163       698,618       1,032,938  

 

The accompanying notes are an integral part of these consolidated financial statements

 

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Nexa Resources S.A.

 

Consolidated statement of changes in shareholders’ equity

Years ended December 31

All amounts in thousands of US dollars, unless otherwise stated

 
 

 

    Capital     Treasury
shares
    Share
premium
    Additional
paid in
capital
    Retained
earnings
(cumulative
deficit)
    Accumulated
other
comprehensive
loss
    Total     Non-
controlling
interests
    Total
shareholders’
equity
 
At January 1, 2018     133,320       -       1,123,755       1,318,728       (53,144 )     (77,356 )     2,445,303       422,068       2,867,371  
Impact of the adoption of IFRS 9     -       -       -       -       (1,818 )     -       (1,818 )     -       (1,818 )
At January 1, 2018 after impacts of the adoption of new standards     133,320       -       1,123,755       1,318,728       (54,962 )     (77,356 )     2,443,485       422,068       2,865,553  
Net income for the year     -       -       -       -       77,026       -       77,026       16,116       93,142  
Other comprehensive loss for the year     -       -       -       -       -       (1,932 )     (1,932 )     (10,219 )     (12,151 )
Total comprehensive (loss) income for the year     -       -       -       -       77,026       (1,932 )     75,094       5,897       80,991  
Decrease in non-controlling interests     -       -       -       -       -       -       -       (2,757 )     (2,757 )
Reimbursement of share premium - USD 0.60 per share     -       -       (80,000 )     -       -       -       (80,000 )     -       (80,000 )
Repurchase of the Company’s own shares     -       (1,352 )     -       -       -       -       (1,352 )     -       (1,352 )
Total contributions by and distributions to shareholders     -       (1,352 )     (80,000 )     -       -       -       (81,352 )     (2,757 )     (84,109 )
At December 31, 2018     133,320       (1,352 )     1,043,755       1,318,728       22,064       (79,288 )     2,437,227       425,208       2,862,435  
Impact of the adoption of IFRS 16     -       -       -       -       71       -       71       -       71  
Impact of the adoption of IFRIC 23     -       -       -       -       (4,023 )     -       (4,023 )     -       (4,023 )
At January 1, 2019 after impacts of the adoption of new standards     133,320       (1,352 )     1,043,755       1,318,728       18,112       (79,288 )     2,433,275       425,208       2,858,483  
Net loss for the year     -       -       -       -       (145,135 )     -       (145,135 )     (12,381 )     (157,516 )
Other comprehensive (loss) income for the year     -       -       -       -       -       (27,318 )     (27,318 )     7,082       (20,236 )
Total comprehensive loss for the year     -       -       -       -       (145,135 )     (27,318 )     (172,453 )     (5,299 )     (177,752 )
Acquisition of non-controlling interests – note 32 (g)     -       -       -       (71,054 )     -       -       (71,054 )     -       (71,054 )
Repurchase of the Company’s own shares     -       (8,103 )     -       -       -       -       (8,103 )     -       (8,103 )
Dividends distribution to NEXA's shareholders - USD 0.53 per share     -       -       -       -       (69,832 )     -       (69,832 )     -       (69,832 )
Dividends distribution to non-controlling interests and to NEXA Peru’s investment shares     -       -       -       (2,256 )     -       -       (2,256 )     (47,300 )     (49,556 )
Total contributions by and distributions to shareholders     -       (8,103 )     -       (73,310 )     (69,832 )     -       (151,245 )     (47,300 )     (198,545 )
At December 31, 2019     133,320       (9,455 )     1,043,755       1,245,418       (196,855 )     (106,606 )     2,109,577       372,609       2,482,186  

 

The accompanying notes are an integral part of these consolidated financial statements

 

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Nexa Resources S.A.

 

Consolidated statement of changes in shareholders’ equity

Years ended December 31

All amounts in thousands of US dollars, unless otherwise stated

 
 

 

    Capital     Treasury
shares
    Share
premium
    Additional
paid in
capital
    Retained
earnings
(cumulative
deficit)
    Accumulated
other
comprehensive
loss
    Total     Non-
controlling
interests
    Total
shareholders’
equity
 
At January 1, 2020     133,320       (9,455 )     1,043,755       1,245,418       (196,855 )     (106,606 )     2,109,577       372,609       2,482,186  
Net loss for the year     -       -       -       -       (559,247 )     -       (559,247 )     (93,259 )     (652,506 )
Other comprehensive loss for the year     -       -       -       -       -       (122,885 )     (122,885 )     (16,827 )     (139,712 )
Total comprehensive loss for the year     -       -       -       -       (559,247 )     (122,885 )     (682,132 )     (110,086 )     (792,218 )
Dividends distribution to NEXA's shareholders - USD 0.38 per share     -       -       -       -       (50,000 )     -       (50,000 )     -       (50,000 )
Cancellation of 881,902 treasury shares acquired for USD 9,455 – note 32 (b)     (882 )     9,455       -       -       (8,573 )     -       -       -       -  
Dividends distribution to non-controlling interests - note 32 (j)     -       -       -       -       -       -       -       (5,332 )     (5,332 )
Capital reduction of subsidiary non-controlling interests - note 32 (i)     -       -       -       -       -       -       -       (13,392 )     (13,392 )
Total contributions by and distributions to shareholders     (882 )     9,455       -       -       (58,573 )     -       (50,000 )     (18,724 )     (68,724 )
At December 31, 2020     132,438       -       1,043,755       1,245,418       (814,675 )     (229,491 )     1,377,445       243,799       1,621,244  

 

The accompanying notes are an integral part of these consolidated financial statements

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 
 

 

1 General information

 

Nexa Resources S.A. (“NEXA”) is a public limited liability company (société anonyme) incorporated and domiciled in the Grand Duchy of Luxembourg. Its shares are publicly traded on the New York Stock Exchange (“NYSE”) and the Toronto Stock Exchange (“TSX”). The Company’s registered office is located at 37A, Avenue J. F. Kennedy in the city of Luxembourg in the Grand Duchy of Luxembourg.

 

NEXA and its subsidiaries (the “Company”) have operations that comprise large-scale, mechanized underground and open pit mines and smelters. The Company owns and operates three polymetallic mines in Peru, and two polymetallic mines in Brazil and is constructing another polymetallic mine in Brazil. The Company also owns and operates a zinc smelter in Peru and two zinc smelters in Brazil.

 

The Company’s majority shareholder is Votorantim S.A. (“VSA”), which holds 64.68% of its equity. VSA is a Brazilian privately-owned industrial conglomerate that holds ownership interests in metal, steel, cement, and energy companies, among others.

 

COVID-19 outbreak impacts on NEXA financial statements and operations

 

In March 2020, the World Health Organization characterized the current COVID-19 disease (“COVID-19”) as a pandemic. Since then, COVID-19 spread across the world with severe effects that impacted the global economy in general and the Company’s business. As a response to COVID-19, the Company implemented and continues to implement additional safety procedures in all its operations to ensure the health and safety of its employees, contractors and communities.

 

The Company remains committed to maintaining the health and safety of its employees, contractors, and communities as well as the continuity of its business. It has implemented measures to mitigate the impacts that COVID-19 has had and could still have on its operations, supply chain, and financial condition, considering the news related to the spreading “second-wave” of this disease around the world.

 

Government authorities in the countries in which the Company operates, especially in Peru, have implemented policies in response to the COVID-19 global outbreak, which negatively affected the Company’s financial position, results of operations and cash flows for the year ended on December 31, 2020, mainly during the second quarter of 2020.

 

In this context, in Peru, on March 15, 2020, the government declared a state of emergency in response to COVID-19, imposing operating restrictions on non-essential industries, which included the mining sector. The restriction period was continuously extended until May 10, 2020 and consequently, mining operations at Cerro Lindo, Atacocha and El Porvenir were suspended during this period and the operation of the Cajamarquilla smelter was reduced to approximately 50% of its production capacity. After the end of the state of emergency, operations at the Cerro Lindo and El Porvenir mining units began a gradual ramp up following personnel mobilization restrictions and strict health and safety protocols. Considering COVID-19 and its impact on the macroeconomic environment, the uncertain time for recovery and the Company’s efforts to reduce costs and improve operational efficiency, in June, the Company decided to place the higher-cost Atacocha underground mine under care and maintenance and only reactivated the operation of the open pit mine of this Unit. Currently, the Company has still not defined how long the underground mine’s suspension will last, and the decision will depend on an improvement in the mine’s economic viability. Given this uncertainty, the Company impaired certain fixed assets exclusively related to Atacocha’s underground operation for a total of USD 10,055 (for more details see note 33 of Impairment of non-current assets) which were considered not recoverable at this moment.

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 
 

 

 

Within this context, currently, although the Peruvian subsidiaries continue to operate subject to additional measures to control and mitigate the spread of COVID-19, they have returned to their adjusted normal production levels except for Atacocha underground which continues suspended as mentioned before. On January 27, 2021 the Peruvian government, among other measures in response to the COVID-19 “second-wave”, declared a new lockdown in certain areas of the country for a two-week period ending on February 14, 2021. This initial period was extended on February 10, 2021 for two more weeks ending on February 28, 2021, with the possibility of being further extended. Currently, the Peruvian operations have not been impacted by these additional measures.

 

In Brazil, the Company’s mining and smelting operations have been operating normally, except for the Juiz de Fora smelter which operated at 60% of its normal production capacity in May and June, in anticipation of a lower market demand due to the global economic conditions. Beginning in July, this smelter returned to operate at its normal production level.

 

Construction activities at the Aripuanã project continue to progress and production is scheduled to start in the beginning of 2022. In October 2020, the original project timeline was extended, and the original capital expenditures estimates were revised upward following a comprehensive study of internal issues and external factors including COVID-19.

 

Although the Company’s operations have returned to normal, the ultimate impact of the COVID-19 global outbreak on the Company’s financial condition, results of operations and cash flows depends on its continuing duration and severity, on the efforts to contain its spread, on the abilities of countries to access and distribute effective vaccines against it, and on the impact of response measures taken by the Company, governments, and others. A new period of disruption or an extended global recession caused by the outbreak, could materially and adversely impact the Company’s results of operations, access to sources of liquidity and overall financial condition. The Company prioritized during the year measures to strengthen its cash position and enhance its short-term liquidity.

 

Management has prepared a cash flow forecast scenario considering the best available information for the next 12 months. This scenario demonstrates that the Company has the financial position, including cash, other liquid resources and an undrawn credit facility, to meet its current financial obligations and therefore, management considers appropriate to adopt the going concern basis of accounting in preparing the consolidated financial statements.

 

2 Information by business segment

 

Business segment definition

 

The Company’s Chief Executive Officer has been identified as the chief operating decision maker (“CODM”) since he has the final authority over resource allocation decisions and performance assessment. The CODM analyzes performance from a product perspective and the Company has identified two reportable segments:

 

        Mining: consists of five long-life polymetallic mines, three located in the Central Andes of Peru and two located in the state of Minas Gerais in Brazil. In addition to zinc, the Company produces substantial amounts of copper, lead, silver and gold as by-products, which reduce the overall cost to produce mined zinc.

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 
 

  

        Smelting: consists of three operating units, one located in Cajamarquilla in Peru and two located in the state of Minas Gerais in Brazil. The facilities recover and produce metallic zinc (SHG zinc and zinc alloys), zinc oxide and by-products, such as sulfuric acid.

 

Accounting policy

 

Segment performance is measured based on Adjusted EBITDA, since financial results, comprising financial income and expenses and other financial items, and income tax are managed at the corporate level and are not allocated to operating segments. Adjusted EBITDA is defined as net (loss) income for the year, adjusted by (i) share in the results of associates, (ii) depreciation and amortization, (iii) net financial results, (iv) income tax, (v) (loss) gain on sale of investments, and (vi) impairment and impairment reversals. In addition, management may adjust the effect of certain types of transactions that in management’s judgment are not indicative of the Company´s normal operating activities or do not necessarily occur on a regular basis.

 

The internal information used for making decisions is prepared using IFRS based accounting measurements and management reclassifications between income statement lines items, which are reconciled to the consolidated financial statements in the column “Adjustments”. These adjustments include reclassifications of the effects of derivative financial instruments from Other income and expenses, net to Net revenues and Cost of sales; and, of certain overhead costs from Other income and expenses, net to Cost of sales and/or Selling, general and administrative expenses.

 

The Company uses customary market terms for intersegment sales. The Company’s corporate headquarters expenses are allocated to the reportable segments to the extent they are allocated in the measures of performance used by the CODM.

 

The presentation of segment results and reconciliation to (loss) income before income tax in the consolidated income statement is as follows:

 

    2020  
    Mining     Smelting     Intersegment
sales
    Adjustments     Consolidated  
Net revenues     748,462       1,550,323       (375,402 )     27,546       1,950,929  
Cost of sales     (625,408 )     (1,287,902 )     375,402       (26,023 )     (1,563,931 )
Gross profit     123,054       262,421       -       1,523       386,998  
                                         
Selling, general and administrative     (70,354 )     (64,874 )     -       (16,391 )     (151,619 )
Mineral exploration and project evaluation     (48,555 )     (5,466 )     -       (3,180 )     (57,201 )
Impairment of non-current assets     (512,706 )     (44,791 )     -       -       (557,497 )
Other income and expenses, net     (23,648 )     (5,545 )     -       10,029       (19,164 )
Operating (loss) income     (532,209 )     141,745       -       (8,019 )     (398,483 )
                                         
Depreciation and amortization     159,984       82,650       -       1,291       243,925  
Impairment of non-current assets     512,706       44,791       -       -       557,497  
Adjusted EBITDA     140,481       269,186       -       (6,728 )     402,939  
                                         
Impairment of non-current assets                                     (557,497 )
Depreciation and amortization                                     (243,925 )
Net financial results                                     (278,175 )
Loss before income tax                                     (676,658 )

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 
 

 

    2019  
    Mining     Smelting     Intersegment
sales
    Adjustments     Consolidated  
Net revenues     1,000,580       1,865,733       (535,776 )     2,178       2,332,715  
Cost of sales     (805,058 )     (1,655,062 )     535,776       (23,484 )     (1,947,828 )
Gross profit     195,522       210,671       -       (21,306 )     384,887  
                                         
Selling, general and administrative     (117,280 )     (89,540 )     -       (9,691 )     (216,511 )
Mineral exploration and project evaluation     (109,549 )     (9,503 )     -       (11 )     (119,063 )
Impairment of non-current assets     (142,133 )     -       -       -       (142,133 )
Other income and expenses, net     (13,955 )     (29,569 )     -       25,318       (18,206 )
Operating (loss) income     (187,395 )     82,059       -       (5,690 )     (111,026 )
                                         
Depreciation and amortization     217,870       97,975       -       2,047       317,892  
Impairment of non-current assets (i)     142,133       -       -       -       142,133  
Adjusted EBITDA     172,608       180,034       -       (3,643 )     348,999  
                                         
Impairment of non-current assets (i)                                     (142,133 )
Depreciation and amortization                                     (317,892 )
Net financial results                                     (104,854 )
Loss before income tax                                     (215,880 )

 

    2018  
    Mining     Smelting     Intersegment
sales
    Adjustments     Consolidated  
Net revenues     1,164,209       2,030,568       (704,031 )     924       2,491,670  
Cost of sales     (711,054 )     (1,878,769 )     704,031       (6,455 )     (1,892,247 )
Gross profit     453,155       151,799       -       (5,531 )     599,423  
                                         
Selling, general and administrative     (54,705 )     (87,929 )     -       (16,969 )     (159,603 )
Mineral exploration and project evaluation     (115,994 )     (11,067 )     -       (2,498 )     (129,559 )
Impairment of non-current assets     -       (3,283 )     -       -       (3,283 )
Other income and expenses, net     (24,435 )     30,428       -       21,582       27,575  
Operating (loss) income     258,021       79,948       -       (3,416 )     334,553  
                                         
Depreciation and amortization     172,357       94,832       -       -       267,189  
Gains on sales of investments and other miscellaneous adjustments (i)     -       -       -       (233 )     (233 )
Impairment of non-current assets (i)     -       -       -       3,283       3,283  
Adjusted EBITDA     430,378       174,780       -       (366 )     604,792  
                                         
Impairment of non-current assets (i)     -       -       -       -       (3,283 )
Gains on sales of investments and other miscellaneous adjustments (i)     -       -       -       -       233  
Depreciation and amortization                                     (267,189 )
Net financial results                                     (202,654 )
Income before income tax                                     131,899  

 

 (i) For the years ended December 31, 2019 and 2018, this line was described as “Exceptional items”.

 

3 Basis of preparation of the consolidated financial statements

 

These consolidated financial statements have been prepared in accordance with International Financial Reporting Standards (“IFRS”) and interpretations issued by the IFRS Interpretations Committee applicable to companies reporting under IFRS, as issued by the International Accounting Standards Board (“IASB”). 

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 
 

 

 The consolidated financial statements have been prepared under the historical cost convention, except for certain financial assets and financial liabilities (including derivative financial instruments) measured at fair value at the end of each reporting period. Certain prior year amounts have been conformed to the current year’s presentation, as disclosed in note 10.

 

The consolidated financial statements of the Company for the year ended December 31, 2020 were approved for issue in accordance with a resolution of the Board of Directors on February 11, 2021.

 

3.1 Revision of the consolidated financial statements

 

During the year ended on December 31, 2020, the Company identified two adjustments in the consolidated financial statements previously issued for years 2019 and 2018. Therefore, the financial statements of these periods have been revised to include these adjustments.

 

(a) Cumulative translation reserve

 

The consolidated statement of changes in shareholders’ equity for the year ended December 31, 2019 has been revised to reflect an adjustment as of December 31, 2019 in the amount of USD 33,650 related to a misclassification affecting the cumulative translation account (“CTA”) within Accumulated other comprehensive loss and Additional paid in capital. This revision did not affect total shareholders’ equity. The Company also revised the Translation adjustment of foreign subsidiaries shown in the consolidated statement of comprehensive income in the same amount for the year ended December 31, 2019.

 

(b) Deferred tax on depreciation of Property, plant and equipment

 

The Company identified a calculation error in its historical tax base for the depreciation of certain Property, plant and equipment which impacted the book/tax temporary differences of these assets and the corresponding deferred tax asset/liability balances generating an accumulated adjustment to deferred tax expenses of USD 41,532 in years prior to 2018 (USD 39,366 as of December 31, 2018 and USD 37,875 as of December 31, 2019) and adjustments to deferred tax benefits in the amounts of USD 2,166 and USD 1,491 in 2018 and 2019, respectively. Such adjustments generated a reallocation of USD 23,201 between deferred tax assets and liabilities, with a net increase effect of USD 14,674 in tax liabilities as of December 31, 2019. The accumulated error has been corrected by revising each of the affected line items in the consolidated income statements, consolidated statements of comprehensive income, consolidated balance sheets and consolidated statements of changes in shareholders' equity for 2019 and 2018.

 

3.1.1 Consolidated financial impacts

 

The following tables summarize the effects on the Company’s consolidated financial statements.

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

 

(a) Consolidated income statement

 

Income tax   (As previously reported)
2019
    Adjustments (i)     (Revised)
2019
 
Deferred     103,255       1,491       104,746  
Net (loss) income for the year     (159,007 )     1,491       (157,516 )
Attributable to NEXA's shareholders     (146,626 )     1,491       (145,135 )
Attributable to non-controlling interests     (12,381 )     -       (12,381 )
Net (Loss) income for the year     (159,007 )     1,491       (157,516 )
Weighted average number of outstanding shares – in thousands     132,622       -       132,622  
Basic and diluted (losses) earnings per share – USD     (1.11 )     0.02       (1.09 )

 

Income tax   (As previously reported)
2018
    Adjustments (i)     (Revised)
2018
 
Deferred     30,864       2,166       33,030  
Net (loss) income for the year     90,976       2,166       93,142  
Attributable to NEXA's shareholders     74,860       2,166       77,026  
Attributable to non-controlling interests     16,116       -       16,116  
Net (Loss) income for the year     90,976       2,166       93,142  
Weighted average number of outstanding shares – in thousands     133,313       -       133,313  
Basic and diluted (losses) earnings per share – USD     0.56       0.02       0.58  

 

(i) Correspond to the deferred tax adjustments as explained in note 3.1 (b).

 

(b) Consolidated statement of comprehensive income

 

    (As previously reported)
2019
    Adjustments (i)     (Revised)
2019
 
Net (loss) income for the year     (159,007 )     1,491       (157,516 )
                         
Other comprehensive (loss) income, net of income tax - items that can be reclassified to the income statement                        
Cash flow hedge accounting     1,332       -       1,332  
Deferred income tax     (453 )     -       (453 )
Translation adjustment of foreign subsidiaries     (54,765 )     33,650       (21,115 )
      (53,886 )     33,650       (20,236 )
                         
Total comprehensive (loss) income for the year     (212,893 )     35,141       (177,752 )
Attributable to NEXA’s shareholders     (207,594 )     35,141       (172,453 )
Attributable to non-controlling interests     (5,299 )     -       (5,299 )
Total comprehensive (loss) income for the year     (212,893 )     35,141       (177,752 )

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

 

    (As previouly reported)
2018
    Adjustments (ii)     (Revised)
2018
 
Net (loss) income for the year     90,976       2,166       93,142  
                         
Other comprehensive (loss) income, net of income tax - items that can be reclassified to the income statement                        
Cash flow hedge accounting     (2,318 )     -       (2,318 )
Deferred income tax     126       -       126  
Translation adjustment of foreign subsidiaries     (9,959 )     -       (9,959 )
      (12,151 )     2,166       (12,151 )
                         
Total comprehensive (loss) income for the year     78,825       2,166       80,991  
Attributable to NEXA’s shareholders     72,928       2,166       75,094  
Attributable to non-controlling interests     5,897       -       5,897  
Total comprehensive (loss) income for the year     78,825       2,166       80,991  

 

(i) Correspond to the CTA adjustment as explained in note 3.1 (a) and to the deferred tax adjustments as in 3.1 (b).

 

(ii) Correspond to the deferred tax adjustments as explained in note 3.1 (b).

 

(c) Consolidated balance sheet

 

    (As previouly reported)          

 

 

(Revised)

 
    2019     Adjustments (i)     2019  
Non-current assets                        
Deferred income tax     262,941       (23,201 )     239,740  
      4,114,216       (23,201 )     4,091,015  
Total assets     5,489,565       (23,201 )     5,466,364  
                         
Non-current liabilities                        
Deferred income tax     273,278       14,674       287,952  
      2,270,514       14,674       2,285,188  
Total liabilities     2,969,504       14,674       2,984,178  
Shareholders’ equity                        
Attributable to NEXA’s shareholders     2,147,452       (37,875 )     2,109,577  
Attributable to non-controlling interests     372,609       -       372,609  
      2,520,061       (37,875 )     2,482,186  
Total liabilities and shareholders’ equity       5,489,565       (23,201 )     5,466,364  

 

(i) Correspond to the deferred tax adjustments as explained in note 3.1 (b).

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

 

(d) Consolidated statement of changes in shareholders’ equity

 

    As previouly reported           Revised  
      Retained earnings (cumulative deficit)       Total
shareholders’ equity
      Adjustments (i)       Retained earnings (cumulative deficit)       Total
shareholders’ equity
 
At January 1, 2018 after impacts of the adoption of new standards     (13,430 )           2,907,085       (41,532 )     (54,962 )      2,865,553  
Net income for the year     74,860       90,976       2,166       77,026       93,142  
Other comprehensive loss for the year     -       (12,151 )     -       -       (12,151 )
Total comprehensive (loss) income for the year     74,860       78,825       2,166       77,026       80,991  
Total contributions by and distributions to shareholders     -       (84,109 )     -       -       (84,109 )
At December 31, 2018     61,430       2,901,801       (39,366 )     22,064       2,862,435  

 

(i) Correspond to the deferred tax adjustments as explained in note 3.1 (b).

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

 

    As previouly reported                 Revised  
    Additional paid in capital     Retained earnings (cumulative deficit)     Accumulated other comprehensive loss     Non-controlling interests     Total shareholders’ equity     Adjustments (i)     Adjustments (ii)     Additional paid in capital     Retained earnings (cumulative deficit)     Accumulated other comprehensive loss     Non-controlling interests     Total shareholders’ equity  
At January 1, 2019 after impacts of the adoption of new standards     1,318,728       57,478       (79,288 )     425,208       2,897,849       -       (39,366 )     1,318,728       18,112       (79,288 )     425,208       2,858,483  
 Net loss for the year     -       (146,626 )     -       (12,381 )     (159,007 )     -       1,491       -       (145,135 )     -       (12,381 )     (157,516 )
 Other comprehensive (loss) income for the year     -       -       (60,968 )     7,082       (53,886 )     33,650       -       -       -       (27,318 )     7,082       (20,236 )
 Total comprehensive loss for the year     -       (146,626 )     (60,968 )     (5,299 )     (212,893 )     33,650       1,491       -       (145,135 )     (27,318 )     (5,299 )     (177,752 )
 Capital increase from non-controlling interests     -       -       -       33,650       33,650       (33,650 )     -       -       -       -       -       -  
 Acquisition of non-controlling interests     (37,404 )     -       -       (33,650 )     (71,054 )     -/+33,650       -       (71,054 )     -       -       -       (71,054 )
 Repurchase of the Company’s own shares     -       -       -       -       (8,103 )     -       -       -       -       -       -       (8,103 )
 Dividends distribution to NEXA's shareholders - USD 0.53 per share     -       (69,832 )     -       -       (69,832 )     -       -       -       (69,832 )     -       -       (69,832 )
 Dividends distribution to non-controlling interests and to NEXA Peru’s investment shares     (2,256 )     -       -       (47,300 )     (49,556 )     -       -       (2,256 )     -       -       (47,300 )     (49,556 )
 Total contributions by and distributions to shareholders     (39,660 )     (69,832 )     -       (47,300 )     (164,895 )     (33,650 )     -       (73,310 )     (69,832 )     -       (47,300 )     (198,545 )
 At December 31, 2019     1,279,068       (158,980 )     (140,256 )     372,609       2,520,061       -/+ 33,650       (37,875 )     1,245,418       (196,855 )     (106,606 )     372,609       2,482,186  

 

(i) Correspond to the CTA adjustment as explained in note 3.1 (a), through which the amount of US$ 33,650 reduces Additional paid capital and increases Accumulated other comprehensive loss, eliminating also the effect in the Non-controlling interests.

 

(ii) Correspond to the deferred tax adjustments as explained in note 3.1 (b).

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

4 Principles of consolidation

 

The consolidated financial statements comprise the financial statements of NEXA and its subsidiaries at December 31, 2020.

 

(a) Subsidiaries

 

Subsidiaries include all entities over which the Company has control. The Company controls an entity when it (i) has the power over the entity; (ii) is exposed, or has the right, to variable returns from its involvement with the entity; and (iii) has the ability to affect those returns through its power over the entity. Subsidiaries are fully consolidated from the date on which control is transferred to the Company, except when the predecessor basis of accounting is applied. Subsidiaries are deconsolidated from the date that control ceases.

 

Accounting policies of subsidiaries are usually consistent with the policies adopted by the Company. If there are differences, to ensure the standardization of the accounting policies, an adjustment is performed in the consolidation process.

 

Non-controlling interests in the equity and results of subsidiaries are shown separately in the consolidated balance sheet, income statement, statement of comprehensive (loss) income and statement of changes in shareholders’ equity.

 

A change in ownership interest of a subsidiary, without loss of control, is accounted for as an equity transaction.

 

If the Company loses control over a subsidiary, it derecognizes the related assets, liabilities, non-controlling interest and other components of equity and any resultant gain or loss is recognized in profit or loss. Any investment retained is recognized at fair value.

 

In general, there is a presumption that a majority of voting rights results in control. When the Company has less than a majority of the voting rights of an investee, it considers all relevant facts and circumstances to determine whether it has power over this investee. This may include contractual arrangements with the other vote holders in the investee; rights arising from other contractual arrangements and the Company’s voting rights and potential voting rights that will give it the practical ability to direct the relevant activities of the investee unilaterally.

 

Intercompany transactions, balances, and unrealized gains on transactions between companies in the consolidated group are eliminated in full on consolidation. Unrealized losses are also eliminated unless the transaction indicates impairment of the transferred asset.

 

(b) Joint operations

 

The Company recognizes its direct right to the assets, liabilities, revenues and expenses of joint operations and its share of any jointly held assets or incurred liabilities and revenues and expenses. These have been included in the consolidated financial statements under the appropriate headings.

 

A joint operation is a joint arrangement whereby the parties that have joint control of the arrangement have rights to the assets, and obligations for the liabilities, relating to the arrangement. Joint control is the contractually agreed sharing of control of an arrangement, which exists only when decisions about the relevant activities require unanimous consent of the parties sharing control.

 

Transactions, balances and unrealized gains and losses between consolidated entities are eliminated.

 

The main entities included in the consolidated financial statements are:

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

 

    Percentage of shares   Company
controls
  Headquarter   Activities
    2020     2019            
Subsidiaries                          
L.D.O.S.P.E.  Geração de Energia e Participações Ltda. - L.D.O.S.P.E."     100.00       100.00   Indirectly   Brazil   Energy
L.D.Q.S.P.E.  Geração de Energia e Participações Ltda. - "L.D.Q.S.P.E."     100.00       100.00   Indirectly   Brazil   Energy
L.D.R.S.P.E.  Geração de Energia e Participações Ltda. - "L.D.R.S.P.E."     100.00       100.00   Indirectly   Brazil   Energy
Mineração Dardanelos Ltda. - "Dardanelos"     100.00       100.00   Indirectly   Brazil   Mining projects
Nexa Recursos Minerais S.A. - "NEXA BR"     100.00       100.00   Directly   Brazil   Mining / Smelting
Mineração Santa Maria Ltda.     99.99       99.99   Indirectly   Brazil   Mining projects
Pollarix S.A. - "Pollarix" (i)     33.33       33.33   Indirectly   Brazil   Holding and others
Karmin Holding Ltda.     100.00       100.00   Indirectly   Brazil   Holding and others
Mineração Rio Aripuaña Ltda.     100.00       100.00   Indirectly   Brazil   Holding and others
Votorantim Metals Canada Inc.     100.00       100.00   Indirectly   Canada   Holding and others
Nexa Resources El Porvenir S.A.C.     99.99       99.99   Indirectly   Peru   Mining
Minera Pampa de Cobre S.A.C     99.99       99.99   Indirectly   Peru   Mining
Nexa Resources Cajamarquilla S.A.  - "NEXA CJM"     99.99       99.99   Directly   Peru   Smelting
Nexa Resources Perú S.A.A. - "NEXA Peru"     80.23       80.23   Indirectly   Peru   Mining
Nexa Resources Atacocha S.A.A. - "NEXA Atacocha"     66.62       66.62   Indirectly   Peru   Mining
Nexa Resources UK Ltd.  - "NEXA UK"     100.00       100.00   Indirectly   United Kingdom   Mining
Nexa Resources US. Inc.     100.00       100.00   Directly   United States   Trading
Joint-operation                          
Campos Novos Energia S.A. - "Enercan"     20.98       20.98       Brazil   Energy
Cia. Minera Shalipayco S.A.C     75.00       75.00       Peru   Mining projects

(i) NEXA BR owns all the common shares of Pollarix, which represents 33.33% of its total share capital. The remaining shares are preferred shares with limited voting rights, which are owned by NEXA’s controlling shareholder, VSA.

 

(c) Transactions with non-controlling interests

 

Transactions with non-controlling interests that do not result in a loss of control are recognized within shareholders’ equity as transactions with equity owners of the consolidated group. A change in ownership interest results in an adjustment between the carrying amounts of the controlling and non-controlling interests to reflect their relative interests in the subsidiary. Any difference between the amount of the adjustment to non-controlling interests and any consideration paid or received is recognized in Additional paid in capital within shareholders’ equity.

 

(d) Foreign currency translation

 

(i) Functional and presentation currency

 

Items included in the financial statements of each of the Company’s entities are measured using the currency of the primary economic environment in which the entity operates (“the functional currency”). The Company’s consolidated financial statements are presented in US Dollars ("USD"), which is NEXA’s functional currency and the Company’s reporting currency.

 

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Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

(ii)  Transactions and balances

 

Foreign currency transactions are initially recorded by each entity in the Company at their respective functional currency spot rates at the date the transaction is recognized. Foreign exchange gains and losses resulting from the settlement of such transactions and from the translation of monetary assets and liabilities denominated in foreign currencies at the functional currency spot rates at the end of each reporting period are recognized in the income statement. Non-monetary items that are measured at historical cost in a foreign currency are translated using the exchange rates at the dates of the initial transaction. Translation differences on assets and liabilities carried at fair value are reported as part of the fair value gain or loss.

 

(iii)  Consolidated entities

 

The results of operations and financial position of consolidated entities that have a functional currency different from the reporting currency of the Company are translated into the reporting currency as follows:

 

· Assets and liabilities for each balance sheet presented are translated at the closing rate at the date of that balance sheet;

 

· Income and expenses for each income statement and statement of comprehensive income presented are translated at average exchange rates for the annual period of that income statement and statement of comprehensive income, which are a reasonable approximation of the cumulative effect of the rates prevailing on the transaction dates; and

 

· All resulting exchange differences are recognized in other comprehensive income and accumulated in a separate component of shareholders’ equity.

 

5 Changes in the main accounting policies and disclosures

 

(a) New standards and amendments – applicable January 1, 2020

 

There are several new standards and amendments effective for annual periods commencing on or after January 1, 2020. The adoption of these new standards did not have an impact on the Company’s financial statements. The Company has not early adopted any other standard, interpretation or amendment that has been issued but is not yet effective and does not expect that the adoption of such standard, interpretation or amendment will have a material impact on the Company’s financial statements.

 

(b) Benchmark interest rate reform

 

In 2014, developments in the global markets revealed weaknesses in the LIBOR’s sustainability as a reference rate. Since then, regulators around the world have focused on the transition to a new benchmark that would replace the USD Libor.

 

In July 2017, the Financial Conduct Authority announced its intention to phase out LIBOR by the end of 2021.

 

However, there still is uncertainty around the timing and precise nature of these changes.

 

The Company is discussing with the financial entities which interest rate reference will replace the loans measured by LIBOR, among other changes, and expects to apply the current benchmarks until the end of 2021, not expecting any significant impacts.

 

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Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

(c) Critical estimates and judgments

 

The preparation of the Company’s consolidated financial statements requires the use of judgments, estimates and assumptions that affect the reported amounts of revenues, expenses, assets and liabilities, the accompanying disclosures, and the disclosure of contingent liabilities at the date of the consolidated financial statements. Accounting estimates and assumptions, by definition, will seldom equal the actual results and are continually evaluated to reflect changing expectations about future events. Management also needs to exercise judgment in applying the Company’s accounting policies.

 

This note provides an overview of the areas that involve a higher degree of judgment or complexity, and of items which are more likely to be materially adjusted due to estimates and assumptions turning out to be wrong due to their uncertainty. Detailed information about each of these estimates and judgments is included in other notes together with information about the basis of calculation for each affected item in the financial statements.

 

The critical accounting estimates and judgments applied by the Company in the preparation of these financial statements are as follows:

 

• estimation of current and deferred income taxes – note 11

• estimation of fair value of financial instruments – note 14

• estimation of quantification of mineral reserves and resources for useful life calculation – note 24

• estimation of asset retirement obligations – note 28

• estimation of provisions for legal claims – note 29

• estimation of contractual obligations – note 30

• estimation of impairment of non-current assets – note 33

 

Estimates and judgments are continually evaluated. They are based on historical experience and other factors, including expectations of future events that may have a financial impact on the Company and that are believed to be reasonable under the circumstances.

 

The Company has considered the effects of COVID-19 when making its estimates and judgments, considering that this pandemic has negatively impacted the Company’s financial position, results of operations and cash flows for the year ended December 31, 2020. Events and changes in circumstances arising after December 31, 2020, including those resulting from the impacts of COVID-19, will be reflected in management’s estimates for future periods.

 

(d) Adoption of IFRS 16 and IFRIC 23

 

The Company has applied IFRS 16 and IFRIC 23 from its mandatory adoption date of January 1, 2019, using the simplified transition approach and did not restate comparative amounts for the periods prior to the adoption.

 

6 Net revenues

 

Accounting policy

 

Revenues represent the fair value of the consideration received or receivable for the sale of goods in the ordinary course of the Company’s activities. Revenues are shown net of value-added tax, returns, rebates and discounts, after eliminating sales between the consolidated companies.

 

The Company recognizes revenues when a performance obligation is satisfied by transferring a promised good or service to a customer. The asset is transferred when the customer obtains control of that asset. To determine the point in time at which a customer obtains control of a promised asset the Company considers the following indicators: (i) the Company has a present right to payment for the asset; (ii) the customer has legal title to the asset; (iii) the Company has transferred physical possession of the asset; (iv) the customer has the significant risks and rewards of ownership of the asset; (v) the customer has accepted the asset.

 

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Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

Identification and timing of satisfaction of performance obligations

 

The Company has two distinct performance obligations included in certain sales contracts, being:

 

(i) the promise to provide goods to its customers, and (ii) the promise to provide freight services to its customers.

 

Promise to provide goods: this performance obligation is satisfied when the control of such goods is transferred to the final customer, which is substantially determined based on the Incoterms agreed upon in each of the contracts with customers.

 

Promise to provide freight services: this performance obligation is satisfied when the freight service contracted to customers is completed.

 

As a result of the distinct performance obligations identified, part of the Company’s revenues is presented as revenues from services. Cost related to revenues from services is presented as “Cost of sales”.

 

Revenues from the sale of goods and from freight services are recognized at a point in time when control is transferred and when contracted services are provided.

 

Determining the transaction price and the amounts allocated to performance obligations

 

The Company considers the terms of the contract and its customary business practices to determine the transaction price. The transaction price is the amount of consideration that the Company expects to be entitled to receive in exchange for transferring promised goods or services to its customers. Transaction price is allocated to each performance obligation on a relative standalone selling price basis.

 

The transaction prices included in the Company’s sales contracts are mainly based on international prices references and subject to price adjustments based on the market price at the end of the relevant quotation period stipulated in the sales contract. These are referred to as provisional pricing arrangements which are subject to a monthly price adjustment. As of December 31, 2020, these price adjustments were not material.

 

Additionally, the Company has a contractual obligation related to a long-term silver streaming arrangement linked to specific production of its Cerro Lindo mine. The Company received an upfront payment in advance of this specific production. The transaction price is linked to the silver production and spot market prices, which change over time and, therefore, it is accounted for as variable consideration. For more details about this streaming transaction see note 30.

 

(a) Composition of net revenues

 

(i) Gross revenues reconciliation

 

    2020     2019     2018  
Gross revenues     2,138,786       2,552,275       2,779,008  
Revenues from products     2,074,203       2,473,534       2,708,112  
Revenues from services     64,583       78,741       70,896  
Taxes on sales     (184,714 )     (216,141 )     (283,848 )
Return of products sales     (3,143 )     (3,419 )     (3,490 )
Net revenues     1,950,929       2,332,715       2,491,670  

 

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Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

(ii) Net revenues from products

 

    2020     2019     2018  
Zinc     1,323,287       1,592,050       1,817,139  
Lead     161,964       259,238       283,861  
Copper     197,756       174,697       151,939  
Silver     58,568       63,867       66,112  
Other     144,771       164,122       101,723  
Net revenues from products     1,886,346       2,253,974       2,420,774  
                         
Taxes on sales     184,714       216,141       283,848  
Return of products sales     3,143       3,419       3,490  
Gross revenues from products     2,074,203       2,473,534       2,708,112  

 

(b) Information on geographical areas in which the Company operates

 

The geographical areas are determined based on the location of the Company’s customers. The net revenues of the Company, classified by geographical location and currency, are as follows:

 

(i) Net revenues by geographical location

 

    2020     2019     2018  
Brazil     583,141       625,033       693,409  
Peru     485,850       595,601       674,228  
United States     116,717       159,672       141,131  
South Korea     77,429       95,913       54,894  
Singapore     76,724       99,488       37,506  
Luxembourg     76,072       145,493       172,791  
Switzerland     68,912       101,636       126,156  
Argentina     56,165       60,850       90,338  
Chile     48,969       80,849       51,215  
Japan     46,719       71,352       93,474  
Austria     35,197       39,897       40,531  
Colombia     34,768       37,149       51,724  
Germany     33,869       20,749       20,906  
Belgium     30,174       25,500       68,703  
Taiwan     28,764       33,551       62,789  
Turkey     25,005       33,905       48,265  
Malaysia     13,948       6,535       3,255  
Netherlands     11,740       9,381       11,550  
Vietnam     10,798       3,142       1,211  
Italy     9,895       9,000       5,327  
Ecuador     9,095       13,012       17,640  
Indonesia     8,609       1,098       5,613  
China     1,286       9,940       9,538  
Other     61,083       53,969       9,476  
Net revenues     1,950,929       2,332,715       2,491,670  

 

(ii) Net revenues by currency

 

    2020     2019     2018  
USD     1,388,746       1,731,765       1,806,590  
Brazilian Real (“BRL”)     562,183       600,950       685,080  
Net revenues     1,950,929       2,332,715       2,491,670  

 

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Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

7 Expenses by nature

 

                      2020     2019     2018  
    Cost of sales
(i)
    Selling,
general and
administrative
    Mineral
exploration and
project
evaluation
    Total     Total     Total  
Raw materials and consumables used     (850,507 )     (5,793 )     -       (856,300 )     (1,063,094 )     (1,086,974 )
Third-party services     (314,655 )     (57,546 )     (35,494 )     (407,695 )     (574,228 )     (471,266 )
Depreciation and amortization     (238,164 )     (5,739 )     (22 )     (243,925 )     (317,892 )     (267,189 )
Employee benefit expenses     (146,162 )     (55,907 )     (11,796 )     (213,865 )     (254,251 )     (262,964 )
Other expenses     (14,443 )     (26,634 )     (9,889 )     (50,966 )     (73,937 )     (93,016 )
      (1,563,931 )     (151,619 )     (57,201 )     (1,772,751 )     (2,283,402 )     (2,181,409 )

 

(i) Refer to note 20 for information about idle capacity costs and inventory impairment, both mainly associated with the COVID-19 outbreak.

 

8 Mineral exploration and project evaluation

 

Accounting policy

 

Mineral exploration and project evaluation activities involve the search for mineral resources and the determination of commercial viability and technical feasibility of an identified resource. Mineral exploration costs include gathering exploration data through geological and geophysical studies, conducting exploratory drilling and sampling, and determining and examining the volume and grade of the identified resources. Project evaluation costs are mainly related to scoping, pre-feasibility and feasibility studies for greenfield and brownfield projects. Additionally, these evaluation costs could also include costs incurred for studies related to research, innovation and technology projects.

 

The Company starts to capitalize a project’s exploration and evaluation costs at the beginning of its feasibility study phase, following completion of a pre-feasibility study in which probability of economic feasibility has been established and where there is sufficient geologic and economic certainty of converting mineral resources into proven and probable mineral reserves at a development stage (construction or execution phase) or production stage based on various factors including the known geology, metallurgy and life-of-mine plans.

 

Capitalized exploration and evaluation costs are presented as Property, plant, and equipment within Mining projects until the project starts its development stage. As further explained in note 23, the costs incurred during the project´s development stage are also capitalized under Property, plant, and equipment but within Assets and projects under construction. In this way, the capitalized exploration and evaluation costs will remain within Mining projects and will only be depreciated once the development stage finishes and the project´s operation starts.

 

Costs to acquire exploration rights are included as Intangible within Rights to use natural resources as explained in note 24.

 

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Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

Composition of mineral exploration and project evaluation costs

 

    2020     2019     2018  
Mineral exploration     (38,519 )     (79,838 )     (86,463 )
Project evaluation     (18,682 )     (39,225 )     (43,096 )
      (57,201 )     (119,063 )     (129,559 )

 

Mineral exploration and project evaluation costs decreased in 2020, mainly because the Company revised its short-term capital allocation, temporarily postponed its greenfield projects and reduced its exploration expenses in response to COVID-19. The effects of the temporary suspension of such projects have been reflected in the Company’s cash flow estimates for the impairment tests made in 2020.

 

9 Other income and expenses, net

 

    2020     2019     2018  
Tax credits     5,473       4,721       37,582  
Remeasurement of environmental obligations     3,112       2,477       12,078  
Derivative financial instruments - note 17 (b)     948       (833 )     17,528  
(Loss) gain on sale of property, plant and equipment and intangible assets     (2,268 )     (857 )     (9,884 )
Gain on sale of investments     -       -       348  
Contribution to communities     (4,658 )     (5,205 )     (13,445 )
(Provision) reversal of legal claims     (10,912 )     (4,424 )     (3,671 )
Other operating income (expenses), net     (10,859 )     (14,085 )     (12,961 )
      (19,164 )     (18,206 )     27,575  

 

10 Net financial results

 

  2020     2019     2018  
Financial income                  
Interest income on financial investments and cash equivalents     7,295       20,909       26,062  
Interest on tax credits     854       5,498       26,033  
Other financial income     3,019       4,647       15,414  
      11,168       31,054       67,509  
                         
Financial expense                        
Interest on loans and financings     (97,422 )     (67,369 )     (77,647 )
Premium paid on bonds repurchase (i)     (14,481 )     -       -  
Interest on contractual obligations     (6,182 )     (6,526 )     (7,294 )
Interest on other liabilities     (8,051 )     (10,864 )     (4,763 )
Interest on lease liabilities – note 25 (b)     (1,757 )     (3,416 )     -  
Other financial expenses     (31,866 )     (29,224 )     (29,420 )
      (159,759 )     (117,399 )     (119,124 )
                         
Other financial items, net (ii)                     -  
Foreign exchange loss (iii)     (120,809 )     (12,893 )     (148,501 )
Derivative financial instruments - note 17 (b)     (717 )     1,024       (2,538 )
Fair value of loans and financings – note 26 (c)     (8,058 )     (6,640 )     -  
      (129,584 )     (18,509 )     (151,039 )
 Net financial results     (278,175 )     (104,854 )     (202,654 )

 

(i) Amount related to the premium paid on the bonds repurchased in the tender offer made on February 24, 2020. Refer to note 26 (b) for additional information.

 

(ii) Since September 30, 2020, the Company is presenting the income and expenses from derivative financial instruments and from the changes in the fair value of loans and financings on a net basis, which is how management analyzes these items. Consequently, the Company has adjusted the Financial income and the Financial expenses subtotals for the comparative periods in the income statement.

 

 

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Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

(iii) The amount in 2020 includes USD 65,689 of foreign exchange losses related to the outstanding USD denominated intercompany debt of NEXA BR with NEXA. Intercompany loans balances are fully eliminated in the consolidated financial statements. However, the related foreign exchange gain or loss is not, and is presented as foreign exchange effects. As of December 31, 2020, the outstanding intercompany loan was of USD 250,572 (December 31, 2019: USD 250,570).

 

11 Current and deferred income tax

 

Accounting policy

 

The current income tax is calculated based on the tax laws enacted or substantively enacted as of the balance sheet date in the countries where the entities operate and generate taxable income. Management periodically evaluates positions taken by the Company in the taxes on income returns with respect to situations in which the applicable tax regulations are subject to interpretation. It establishes provisions, where appropriate, considering amounts expected to be paid to the tax authorities.

 

The current income tax is presented net, separated by tax paying entity, in liabilities when there are amounts payable, or in assets when the amounts prepaid exceed the total amount due on the reporting date.

 

Deferred income tax is provided in full, using the balance sheet liability method, on temporary differences arising between the tax bases of assets and liabilities and their carrying amounts for financial reporting purposes at the reporting date. However, deferred tax liabilities are not recognized if they arise from the initial recognition of goodwill. Deferred income tax is also not accounted for if it arises from the initial recognition of an asset or liability in a transaction other than a business combination that, at the time of the transaction affects neither the accounting nor the taxable income or loss. Deferred income tax is determined using tax rates (and laws) that have been enacted or substantially enacted at the end of the reporting period and are expected to apply when the related deferred income taxes asset is realized, or the deferred income tax liability is settled.

 

Deferred tax assets are recognized only to the extent it is probable that future taxable income will be available against which the temporary differences and/or tax losses can be utilized. Deferred tax assets and liabilities are offset when there is a legally enforceable right and an intention to offset them in the calculation of current taxes, generally when they are related to the same legal entity and the same tax authority. Accordingly, deferred tax assets and liabilities in different entities or in different countries are generally presented separately, and not on a net basis.

 

Deferred tax liabilities and assets are not recognized for temporary differences between the carrying amounts and tax bases of investments in foreign operations where the Company is able to control the timing of the reversal of the temporary differences and it is probable that the differences will not be reversed in the near future.

 

Critical accounting estimates and judgments

 

The Company is subject to income tax in all countries in which it operates where uncertainties arise in the application of complex tax regulations. Significant judgment, estimates and assumptions are required to determine the amount of deferred taxes that would be recovered since this amount may be affected by factors including, but not limited to: (i) internal assumptions on the projected taxable income, which are based on production and sales planning, commodity prices, operational costs and planned capital costs; (ii) macroeconomic environment; and (iii) trade and tax scenarios.

 

In addition, there are many transactions and calculations for which the ultimate tax determination is uncertain. The Company also exercises judgment in the identification of these uncertainties over income tax treatments which could impact the consolidated financial statements as the Company operates in a complex multinational environment.

 

The Company and its subsidiaries are subject to reviews of income tax filings and other tax payments, and disputes can arise with the taxing authorities over the interpretation of the applicable laws and regulations.

 

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Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

(a) Reconciliation of income tax (expense) benefit

 

    2020     2019     2018  
(Loss) income before income tax     (676,658 )     (215,880 )     131,899  
Standard rate (i)     24.94 %     24.94 %     26.01 %
                         
Income tax (expense) benefit at standard rate     168,759       53,840       (34,307 )
Difference in tax rate of subsidiaries outside Luxembourg     36,390       24,698       (11,227 )
Special mining levy and special mining tax     (5,909 )     (7,431 )     (14,565 )
Deferred tax on net operating losses (ii)     (35,849 )     -       -  
Withholding tax on dividends paid by subsidiaries     -       (9,764 )     -  
Tax effect of translation of non-monetary assets/liabilities to functional currency (iii)     (28,174 )     (3,575 )     (804 )
Impairment of goodwill (iv)     (78,866 )     -       -  
Other permanent tax differences     (32,199 )     596       22,146  
Income tax (expense) benefit     24,152       58,364       (38,757 )
                         
Current     (63,192 )     (46,382 )     (71,787 )
Deferred     87,344       104,746       33,030  
Income tax (expense) benefit     24,152       58,364       (38,757 )

 

(i) On April 25, 2019, the Luxembourg Parliament approved the 2019 Budget Law, including a reduction of the corporate income tax rate from 26.01% to 24.94%, which was maintained for year 2020. When NEXA’s tax credits on net operating losses resulting from its standalone activities do not meet the recognition criteria, no deferred tax assets are recognized.

 

(ii) During 2020, NEXA Atacocha derecognized its deferred tax assets since, in accordance with the Company´s estimates of future taxable income, these assets will not be recovered. These estimates were affected by the COVID-19 which facts and circumstances are described in note 1.

 

(iii) The increase in 2020 is mainly related to the tax effect of the translation of non-monetary assets of the tax base of NEXA’s Peruvian entities, which was impacted by the appreciation of the USD (the functional currency) against the Peruvian Soles “PEN” (local currency).

 

(iv) The Company recognized an impairment of goodwill during 2020 (for additional information refer to note 33). This impairment loss is considered a permanent difference and no deferred income tax benefit has been recognized.

 

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Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

(b)            Analysis of deferred income tax assets and liabilities

 

    2020     2019  
Tax credits on net operating losses (i)     108,767       160,905  
Uncertain income tax treatments (ii)     (6,712 )     (9,779 )
Tax credits on temporary differences                
Foreign exchange losses     33,123       31,027  
Environmental liabilities     16,611       24,293  
Asset retirement obligations     20,507       18,751  
Tax, civil and labor provisions     7,162       6,962  
Other provisions     9,825       7,933  
Provision for obsolete and slow-moving inventory     6,813       5,734  
Provision for employee benefits     5,299       7,270  
Revaluation of derivative financial instruments     3,056       2,864  
Other     6,513       11,517  
                 
Tax debits on temporary differences                
Capitalized interest     (10,274 )     (28,505 )
Revaluation of loans and financings     (88 )     -  
Depreciation, amortization and asset impairment     (190,970 )     (285,427 )
Other     (6,444 )     (1,757 )
      3,188       (48,212 )
                 
Deferred income tax assets     221,580       239,740  
Deferred income tax liabilities     (218,392 )     (287,952 )
      3,188       (48,212 )

 

(i) Tax credits on net operating losses decreased in 2020, mainly because of the BRL devaluation against the USD during the year, which affected the Company’s tax credits from the Company’s Brazilian legal entities.

 

(ii) Uncertain income tax treatments decreased in 2020, mainly because of the settlement of certain income tax uncertain positions in NEXA Peru and NEXA Atacocha.

 

(c)            Effects of deferred income tax on income statement and other comprehensive income

 

    2020     2019     2018  
Balance at beginning of the year     (48,212 )     (136,810 )     (141,950 )
Effect on (loss) income for the year     87,344       104,746       33,030  
Effect on other comprehensive (loss) income     (40,371 )     453       (126 )
Impact of the adoption of IFRIC 23     -       (10,070 )     -  
Foreign exchange (loss) gain     4,427       (6,531 )     (27,764 )
Balance at end of the year     3,188       (48,212 )     (136,810 )

 

(d)            Summary of contingent liabilities on income taxes

 

There are uncertainties and legal proceedings for which it is not probable that an outflow of resources will be required. In such cases, a provision is not recognized. As of December 31, 2020, the main legal proceedings are related to carryforward calculation of net operating losses, deductibility of foreign exchange losses and expenses. The estimated financial effect of these contingent liabilities is USD 163,670 (December 31, 2019: USD 182,380). The decrease in the contingent liabilities on income tax in 2020, is mainly driven by the BRL and PEN devaluations against the USD during the year.

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

12 Financial risk management

 

Financial risk factors

 

The Company’s activities expose it to a variety of financial risks: a) market risk (including currency risk, interest rate risk and commodities risk); b) credit risk; and c) liquidity risk.

 

A significant portion of the products sold by the Company are commodities, with prices pegged to international indices and denominated in USD. Part of the costs of production, however, is denominated in BRL and PEN, and therefore, there is a mismatch of currencies between revenues and costs. Additionally, the Company has debts linked to different indices and currencies, which may impact its cash flows.

 

In order to mitigate the potential adverse effects of each financial risk factor, the Company follows a Financial Risk Management Policy that establishes governance and guidelines for the financial risk management process, as well as metrics for measurement and monitoring. This policy establishes guidelines and rules for: (i) Commodities Exposure Management, (ii) Foreign Exchange Exposure Management, (iii) Interest Rate Exposure Management, (iv) Issuers and Counterparties Risk Management, and (v) Liquidity and Financial Indebtedness Management. All strategies and proposals must comply with the Financial Risk Management Policy guidelines and rules, be presented to and discussed with the Finance Committee of the board of directors, and, when applicable, submitted for the approval of the Board of Directors, under the governance structure described in the Financial Risk Management Policy.

 

(a)  Market risk

 

The purpose of the market risk management process and all related actions are intended to protect the Company’s cash flows against adverse events, such as changes in foreign exchange rates, commodity prices and interest rates, to maintain the ability to pay financial obligations, and to comply with liquidity and indebtedness levels defined by management. The related sensitivity analysis is included in note 18.

 

(i)  Foreign exchange risk

 

Foreign exchange risk is managed through the Company’s Financial Risk Management Policy, which states that the objectives of derivative transactions are to reduce cash flow volatility, hedge against foreign exchange exposure and minimize currency mismatches.

 

Presented below are the financial assets and liabilities in foreign currencies at December 31, 2020. These mainly result from the foreign operations of NEXA BR for which the functional currency is the BRL. The increased economic uncertainty and risks due to the COVID-19 global outbreak introduced significant volatility in foreign exchange rates in relation to the USD that impacted NEXA since the Company has foreign operations mainly related to NEXA BR.

 

Intercompany loans balances are fully eliminated in the consolidated financial statements. However, the related foreign exchange gain or loss is not, and is presented as foreign exchange effects.

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

USD amounts of foreign currency balances   2020     2019  
Assets            
Cash, cash equivalents and financial investments     257,706       109,511  
Derivative financial instruments     22,376       15,596  
Trade accounts receivables     42,612       27,883  
      322,694       152,990  
Liabilities                
Loans and financings     454,372       119,095  
Derivative financial instruments     21,484       16,134  
Trade payables     165,019       194,646  
Lease liabilities     20,792       22,020  
Use of public assets     20,787       23,279  
      682,454       375,174  
Net exposure     (359,760 )     (222,184 )

 

Because of the COVID-19, foreign exchange rates have become more volatile and therefore the Company has been affected by higher variations in its foreign exchange results.

 

(ii)  Interest rate risk

 

The Company's interest rate risk arises mainly from long-term loans. Loans at variable rates expose the Company to cash flow interest rate risk. Loans at fixed rates expose the Company to fair value risk associated with interest rates. For further information related to interest rates, refer to note 26.

 

The Company’s Financial Risk Management Policy establishes guidelines and rules to hedge against changes in interest rates that impact the cash flows of the Company. Exposure to each interest rate is projected until the maturity of the assets and liabilities exposed to this index. Occasionally the Company enters into floating to fixed interest rate swaps to manage its cash flow interest rate risk. In the case of swaps contracted together with loans and financings, the Company accounts for the term loan under the fair value option to eliminate the accounting mismatch that would arise if amortized cost were used (for more information please refer to note 26 (c)).

 

As of December 31, 2020, there have been no significant impacts on the Company’s exposure to interest rate risk as a result of the COVID-19 global outbreak.

 

(iii)  Commodity price risk

 

This risk is related to the volatility in the prices of the Company's commodities. Prices fluctuate depending on demand, production capacity, producers' inventory levels, the commercial strategies adopted by large producers, and the availability of substitutes for these products in the global market.

 

The Company’s Financial Risk Management Policy establishes guidelines to mitigate the risk of fluctuations in commodity prices that could impact the cash flows of the Company. The exposure to the price of each commodity considers the monthly projections of production, purchases of inputs and the maturity flows of hedges associated with them.

 

Commodity prices hedge transactions are classified into the following hedging strategies:

 

Hedges for sales of zinc at a fixed price (Customer Hedge)

 

The objective is to convert fixed prices sales to floating prices, observed on the London Metal Exchange (LME). The purpose of the strategy is to maintain the revenues of a business unit linked to the LME prices. These transactions usually relate to purchases of zinc for future settlement on the over-the-counter market.

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

Hedges for mismatches of quotational periods (Book Hedges)

 

The objective is to hedge quotational periods mismatches arising between the purchases of metal concentrate or processed metal and the sale of the processed metal. These transactions usually relate to purchases and sales of zinc and silver for future trading on the over-the-counter market.

 

Hedges for the operating margin of metals (Strategic Hedges)

 

The objective is to reduce the volatility of the cash flow from LME prices for zinc, copper and silver and ensure a more predicable operating margin. This strategy is carried out through the sale of zinc forward contracts. For NEXA BR, the transaction also involves the sale of USD forward contracts in order to hedge the operating margin in BRL.

 

The increased economic uncertainty and risks that arose from COVID-19 explained the significant decrease in the commodity prices in the first semester of the year. However, with the resumption of the economy since the second semester, the commodities prices are gradually increasing and have impacted the Company’s hedge operations results as of December 31, 2020.

 

(b) Credit risk

 

Trade receivables, derivative financial instruments, term deposits, bank deposit certificates ("CDBs") and government securities create exposure to credit risk with respect to the counterparties and issuers. The Company has a policy of making deposits in financial institutions that have, at least, a rating from two of the following international rating agencies: Fitch, Moody’s or Standard & Poor’s. The minimum rating required for counterparties is A+/A1 (local rating scale) or BBB-/Baa3 (global rating scale). Financial institutions in Peru, where only global rating assessments are available, will be eligible provided they have a rating of "BBB-" at least by one rating agency.

 

The pre-settlement risk methodology is used to assess counterparty risks in derivative transactions. This methodology consists of determining the risk associated with the likelihood (via Monte Carlo simulations) of a counterparty defaulting on the financial commitments defined by contract.

 

The global ratings were obtained from the rating agencies Fitch, Moody’s or Standard & Poor’s ratings and are related to commitments in foreign or local currency and, in both cases, they assess the capacity to honor these commitments, using a scale applicable on a global basis. Therefore, both ratings in foreign currency and in local currency are internationally comparable ratings.

 

The ratings used by the Company are always the most conservative ratings of the referred agencies.

 

In the case of credit risk arising from customer credit exposure, the Company assesses the credit quality of the customer, considering mainly the history of the relationship and financial indicators defining individual credit limits, which are continuously monitored.

 

The Company performs initial analyses of customer credit and, when deemed necessary, guarantees or letters of credit are obtained to mitigate the credit risk. Additionally, most sales to the United States of America, Europe and Asia are collateralized by letters of credit and credit insurance.

 

The carrying amount of the Company’s financial instruments best represents the maximum exposure to their credit risk.

 

The following table reflects the credit quality of issuers and counterparties for transactions involving cash and cash equivalents, financial investments and derivative financial instruments. The variations presented are mainly related to the Company's transactions in the year and not to changes in the counterparties’ ratings.

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

    2020     2019  
    Local
rating
    Global
rating
    Total     Local
rating
    Global
rating
    Total  
Cash and cash equivalents                                                
AAA     131,486       -       131,486       11,243       -       11,243  
AA+     3       -       3       5,997       -       5,997  
AA     30,177       -       30,177       18       99,853       99,871  
AA-     8,754       23,005       31,759       1       10,869       10,870  
A+     -       249,198       249,198       -       156,032       156,032  
A     -       263,375       263,375       -       230,084       230,084  
A-     -       184,087       184,087       -       38,824       38,824  
BBB+     -       111,525       111,525       -       67,467       67,467  
BBB     -       38,848       38,848       -       23,552       23,552  
BBB-     -       30,707       30,707       -       31,416       31,416  
BB-     -       1,956       1,956       -       -       -  
No rating (i)     3       13,039       13,042       3       23,259       23,262  
      170,423       915,740       1,086,163       17,262       681,356       698,618  
                                                 
Financial investments                                                
AAA     32,412       -       32,412       44,985       -       44,985  
AA+     2,257       -       2,257       8,170       -       8,170  
AA     46       -       46       352       -       352  
AA-     329       -       329       656       -       656  
No rating (i)     -       -       -       4,612       -       4,612  
      35,044       -       35,044       58,775       -       58,775  
                                                 
Derivative financial instruments                                                
AAA     2,068       -       2,068       16,025       -       16,025  
AA     -       -       -       -       1,029       1,029  
A+     -       1,977       1,977       -       422       422  
A-     -       27,935       27,935       -       2,048       2,048  
      2,068       29,912       31,980       16,025       3,499       19,524  

  

(i) Refers to subsidiaries of international financial institutions that do not have a global rating available in the international rating agencies. According to the Company's policy, for these financial institutions, the rating of the financial institution controlling entities is assumed, which must be at least BBB-.

 

(c) Liquidity risk

 

This risk is managed through the Company's Financial Risk Management Policy, which aims to ensure the availability of funds to meet the Company’s financial obligations. The main liquidity measurement and monitoring instrument is the cash flow projection, using a minimum projection period of 12 months from the benchmark date.

 

The table below shows the Company's financial obligations to be settled by the Company based on their maturity (the remaining period from the balance sheet up to the contractual maturity date). The amounts below represent the estimated undiscounted future cash flow, which include interest to be incurred and, accordingly, do not reconcile directly with the amounts presented in the consolidated balance sheet.

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

2020   Less than 1
year
    Between 1
and 3 years
    Between 3 and
5 years
    Over 5 years     Total  
Loans and financings     214,614       484,579       459,215       1,490,253       2,648,661  
Lease liabilities     15,999       9,690       -       -       25,689  
Derivative financial instruments     5,390       51       21,374       59       26,874  
Trade payables     370,122       -       -       -       370,122  
Confirming payables     145,295       -       -       -       145,295  
Salaries and payroll charges     56,107       -       -       -       56,107  
Dividends payable     4,557               -       -       4,557  
Related parties     -       561       -       -       561  
Asset retirement and environmental obligations     33,714       53,501       70,444       220,241       377,900  
Use of public assets     1,270       2,943       5,131       20,200       29,544  
      847,068       551,325       556,164       1,730,753       3,685,310  

 

2019   Less than 1
year
    Between 1
and 3 years
    Between 3 and
5 years
    Over 5 years     Total  
Loans and financings     91,511       342,095       610,750       842,222       1,886,578  
Lease liabilities     17,903       16,361       120       -       34,384  
Derivative financial instruments     8,272       6,918       6,577       51       21,818  
Trade payables     414,080       -       -       -       414,080  
Confirming payables     82,770       -       -       -       82,770  
Salaries and payroll charges     58,913       -       -       -       58,913  
Dividends payable     6,662       -       -       -       6,662  
Related parties     -       834       -       -       834  
Asset retirement and environmental obligations     19,001       68,296       76,629       273,484       437,410  
Use of public assets     1,446       3,177       3,581       30,729       38,933  
      700,558       437,681       697,657       1,146,486       2,982,382  

 

In the second quarter of 2020, the Company took measures to enhance its short-term liquidity to mitigate the effects of the economic scenario due to the COVID-19 global outbreak on the Company’s cash flows. Such measures included the strengthening of its cash position by incurring new loans and obtaining new financings. As a result, the total amount of financial liabilities, related to Loans and financings, maturing between less than 1 year increased by the amount of USD 123,103 during 2020.

 

(d) Capital management

 

The Company’s objectives when managing capital are to safeguard its ability to continue as a going concern, so it can continue to provide returns for shareholders and benefits for other stakeholders; and to maintain an optimal capital structure to reduce the cost of capital.

 

In order to maintain or adjust the capital structure, the Company may adjust the level of dividends paid to shareholders, return capital to shareholders, issue new shares or sell assets or metals produced to reduce debt. The Company monitors capital mainly using the leverage ratio, calculated as net debt to Adjusted EBITDA.

 

Net debt and Adjusted EBITDA measures should not be considered in isolation or as a substitute for net income or operating income, as indicators of operating performance, or as alternatives to cash flow as measures of liquidity. Additionally, management’s calculation of Adjusted EBITDA may be different from the calculation used by other companies, including competitors in the mining and smelting industry, so these measures may not be comparable to those of other companies.

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

    Note     2020     2019     2018  
Loans and financings     26       2,024,314       1,508,557       1,424,867  
Derivative financial instruments     17       (5,106 )     2,294       3,017  
Lease liabilities     25       25,689       34,384       -  
Cash and cash equivalents     15       (1,086,163 )     (698,618 )     (1,032,938 )
Financial investments     16       (35,044 )     (58,775 )     (92,233 )
Net debt (i)             923,690       787,842       302,713  
                                 
Net (loss) income for the year             (652,506 )     (157,516 )     93,142  
Plus (less):                                
Depreciation and amortization     23, 24 and 25       243,925       317,892       267,189  
Net financial results     10       278,175       104,854       202,654  
Income tax expense (benefit)     11 (a)     (24,152 )     (58,364 )     38,757  
EBITDA (ii)             (154,558 )     206,866       601,742  
                                 
Impairment of non-current assets (iii)             557,497       142,133       3,283  
Gains on sales of investments and other miscellaneous adjustments (iii)             -       -       (233 )
Adjusted EBITDA (ii)             402,939       348,999       604,792  
                                 
Leverage ratio (Net debt/Adjusted EBITDA)             2.29       2.26       0.50  

 

(i) Net debt is defined as (a) loans and financings, plus lease liabilities, plus or minus (b) the fair value of derivative financial instruments less (c) cash and cash equivalents, less (d) financial investments.

 

(ii) Adjusted EBITDA for capital management calculation uses the same assumptions described in note 2 for Adjusted EBITDA by segment.

 

(iii) For the years ended December 31,2019 and 2018, this line was described as “Exceptional items”.

 

13 Financial instruments

 

Accounting policy

 

Normal purchases and sales of financial assets are recognized on the trade date – the date on which the Company commits to purchase or sell the asset. Financial assets are initially recognized at fair value plus transaction costs for all financial assets not carried at fair value through profit or loss. Financial assets carried at fair value through profit or loss, if any, are initially recognized at fair value, and transaction costs are expensed in the income statement.

 

Financial assets are derecognized when the rights to receive cash flow from the investments have expired or the Company has transferred substantially all of the risks and rewards of ownership. Financial assets at fair value through profit or loss and at fair value through other comprehensive income are subsequently carried at fair value. Financial assets at amortized costs are subsequently measured using the effective interest rate method.

 

Then, the Company classifies its financial assets and liabilities under the following categories: amortized cost, fair value through other comprehensive income and fair value through profit or loss.

 

(i) Amortized cost

 

Financial assets measured at amortized cost are assets held within a business model whose objective is to hold financial assets in order to collect contractual cash flows and for which the contractual terms of the financial asset give rise on specified dates to cash flows that are solely payments of principal and interest (“SPPI”) on the principal amount outstanding.

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

(ii) Fair value through profit or loss

 

Financial assets measured at fair value through profit or loss are assets which an entity manages with the objective of realizing cash flows through the sale of such assets and financial assets that do not give rise to cash flows that are SPPI on the principal amount outstanding.

 

(iii) Fair value through other comprehensive income

 

Financial assets measured at fair value through other comprehensive income are held within a business model whose objective is achieved by both collecting contractual cash flows and selling financial assets and for which the contractual terms of the financial asset give rise on specified dates to cash flows that are SPPI on the principal amount outstanding.

 

(a) Breakdown by category

 

The Company’s current financial assets and liabilities are classified as follows:

 

          2020  
Assets per balance sheet   Note     Amortized cost     Fair value through
profit or loss
    Total  
Cash and cash equivalents     15       1,086,163       -       1,086,163  
Financial investments     16       35,044       -       35,044  
Derivative financial instruments     17 (a)     -       31,980       31,980  
Trade accounts receivables     19       64,262       164,770       229,032  
Related parties (i)     22       2       -       2  
              1,185,471       196,750       1,382,221  

 

          2020  
Liabilities per balance sheet   Note     Amortized cost     Fair value through
profit or loss
    Total  
Loans and financings     26 (a)     1,822,756       201,558       2,024,314  
Lease liabilities     25 (b)     25,689       -       25,689  
Derivative financial instruments     17 (a)     -       26,874       26,874  
Trade payables     27       370,122       -       370,122  
Confirming payables     31       145,295       -       145,295  
Use of public assets (ii)             19,215       -       19,215  
Related parties (i)     22       561       -       561  
              2,383,638       228,432       2,612,070  

 

          2019  
Assets per balance sheet   Note     Amortized cost     Fair value through
profit or loss
    Total  
Cash and cash equivalents     15       698,618       -       698,618  
Financial investments     16       58,775       -       58,775  
Derivative financial instruments     17 (a)     -       19,524       19,524  
Trade accounts receivables     19       107,995       69,236       177,231  
Related parties (i)     22       744       -       744  
              866,132       88,760       954,892  

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

          2019  
Liabilities per balance sheet   Note     Amortized cost     Fair value through
profit or loss
    Total  
Loans and financings     26 (a)     1,411,179       97,378       1,508,557  
Lease liabilities     25 (b)     34,384       -       34,384  
Derivative financial instruments     17 (a)     -       21,818       21,818  
Trade payables     27       414,080       -       414,080  
Confirming payables     31       82,770       -       82,770  
Use of public assets (ii)             23,279       -       23,279  
Related parties (i)     22       834       -       834  
              1,966,526       119,196       2,085,722  

 

(i) Classified as Other assets and liabilities in the consolidated balance sheet.

(ii) Classified as Other liabilities in the consolidated balance sheet.

 

14 Fair value estimates

 

Critical accounting estimates and judgments

 

The fair value of financial instruments that are not traded in an active market is determined using valuation techniques. The Company uses judgment to select among a variety of methods and makes assumptions that are mainly based on market conditions existing at the end of each reporting period.

 

(a) Analysis

 

The main financial instruments and the assumptions made by the Company for their valuation are described below:

 

· Cash and cash equivalents, financial investments, trade accounts receivables and other current assets - considering their nature, terms and maturity, the carrying amounts approximate their fair value.

 

· Financial liabilities - these instruments are subject to the usual market interest rates. The fair value is based on the present value of expected future cash disbursement, at interest rates currently available for debt with similar maturities and terms and adjusted for the Company’s credit risk. Loans and financings are measured at amortized cost, except for certain contracts for which the Company has elected the fair value option.

 

· Derivative financial instruments - the fair value is determined by calculating their present value through yield curves at the closing dates. The curves and prices used in the calculation for each group of instruments are developed based on data from Brazilian Securities, Commodities and Futures Exchange - B3, Central Bank of Brazil, LME and Bloomberg, interpolated between the available maturities. The main derivative financial instruments are:

 

· Swap contracts - the present value of both the assets and liabilities are calculated through the discount of forecasted cash flow by the interest rate of the currency in which the swap is denominated. The difference between the present value of the assets and the liabilities generates its fair value.

 

· Forward contracts – the present value is estimated by discounting the notional amount multiplied by the difference between the future price at the reference date and the contracted price. The future price is calculated using the convenience yield of the underlying asset. It is common to use Asian non-deliverable forwards for hedging non-ferrous metals positions. Asian contracts are derivatives in which the underlying is the average price of certain asset over a range of days.

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

· Option contracts - the present value is estimated based on the Black and Scholes model, with assumptions that include the underlying asset price, strike price, volatility, time to maturity and interest rate. The underlying asset price is the average price of the foreign exchange rate in the fixing month.

 

(b) Fair value by hierarchy

 

          2020  
    Note     Level 1     Level 2     Total  
Assets                        
Derivative financial instruments     17       -       31,980       31,980  
Trade accounts receivables             -       164,770       164,770  
              -       196,750       196,750  
Liabilities                                
Derivative financial instruments     17       -       26,874       26,874  
Loans and financings designated at fair value (i)             -       201,558       201,558  
              -       228,432       228,432  

 

          2019  
          Level 1     Level 2     Total  
Assets                        
Derivative financial instruments     17       -       19,524       19,524  
Trade accounts receivables             -       69,236       69,236  
              -       88,760       88,760  
Liabilities                                
Derivative financial instruments     17       -       21,818       21,818  
Loans and financings designated at fair value (i)             -       97,378       97,378  
              -       119,196       119,196  

 

(i) As explained above, certain loans and financings are measured at fair value. The carrying amount of other financial instruments measured at amortized cost do not differ significantly from their fair value.

 

The Company discloses fair value measurements based on their level of the following fair value measurement hierarchy:

 

Level 1:

 

Quoted prices (unadjusted) in active markets for identical assets and liabilities traded in active markets at the balance sheet date. A market is regarded as active if quoted prices are readily and regularly available from an exchange, dealer, broker, industry group, pricing service, or regulatory agency, and those prices represent actual and regularly occurring market transactions on an arm's length basis. The quoted market price used for financial assets held by the Company is the current bid price.

 

Level 2:

 

Financial instruments not traded in an active market for which fair value is determined using valuation techniques, when all of the significant inputs required to identify the fair value of an instrument are observable. Specific valuation techniques used to value financial instruments include:

 

· Quoted market prices or dealer quotes for similar instruments are used where available;

 

· The fair values of interest rate swaps are calculated at the present value of the estimated future cash flow based on observable yield curves; and

 

· The fair value of forward foreign exchange contracts is determined using forward exchange rates at the balance sheet date, with the resulting value discounted to present value.

 

Other techniques, such as discounted cash flow analysis, are used to determine the fair value for the remaining financial instruments.

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

Level 3:

 

Inputs for the asset or liability that are not based on observable market data (that is, unobservable inputs) are classified as Level 3. As of December 31, 2020, there were no financial assets and liabilities carried at fair value classified as Level 3.

 

Fair value estimates were assessed by the Company to evaluate the impacts of the COVID-19 and the only impact identified is related to the changes in the Company’s credit risk which affect the fair value of debts which are designated as fair value option. Refer to note 26.

 

15 Cash and cash equivalents

 

Accounting policy

 

Cash and cash equivalents include cash, bank deposits, and highly liquid short-term investments (investments with an original maturity less than 90 days), which are readily convertible into a known amount of cash and subject to an immaterial risk of changes in value. Bank overdrafts are shown within Loans and financings in current liabilities in the balance sheet.

 

(a) Composition

 

    2020     2019  
Cash and banks     113,017       299,374  
Term deposits (i)     973,146       399,244  
      1,086,163       698,618  

 

Cash and cash equivalents balance increased as of December 31, 2020, mainly because of the new loans and financings taken by the Company during the first half of 2020 as explained in note 26.

 

(i) As part of its strategy to enhance liquidity during 2020 and to meet its cash operating commitments, the Company made a reclassification of USD 29,496 from Financial investments to Cash and cash equivalents.

 

(b)  Changes in operating assets and liabilities

 

    2020     2019     2018  
Decrease (increase) in assets                  
Trade accounts receivables     (68,986 )     (8,634 )     8,537  
Inventory     8,883       (35,425 )     52,472  
Other assets     30,538       (45,891 )     (133,716 )
                         
Increase (decrease) in liabilities                        
Trade payables     21,589       18,823       57,411  
Confirming payables     62,525       12,278       (40,613 )
Contractual liabilities     (20,683 )     (25,641 )     (29,543 )
Other liabilities     58,594       12,856       32,412  
      92,460       (71,634 )     (53,040 )

 

(c)  Non-cash transactions

 

During 2020, the Company had additions related to asset retirement obligations in the amount of USD 14,874 (2019: USD 28,337); additions to right-of-use assets in the amount of USD 5,785 (2019: USD 3,517) and liabilities to increase property, plant and equipment in the amount of USD 4,137.

 

38 of 77 

 

 

 

Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

16 Financial investments

 

Accounting policy

 

Financial investments are mainly short-term investments that do not meet the definition of cash and cash equivalents. The financial investments are used as part of the cash-management strategy of the Company and are measured at amortized cost.

 

(a) Composition

 

    2020     2019  
Investment fund quotas   28,256     28,126  
Bank deposit certificates   6,788     25,540  
Other   -     5,109  
    35,044     58,775  

 

Financial investments decreased as of December 31, 2020, mainly because of the reclassification of funds to Cash and cash equivalents as explained in note 15.

 

17 Derivative financial instruments

 

Accounting policy

 

Derivatives are initially recognized at fair value as at the date on which a derivative contract is entered into and are subsequently measured at fair value. Derivatives are only used for risk mitigation purposes and not as speculative investments. When derivatives do not meet the hedge accounting criteria, they are classified as held for trading and accounted for at fair value through profit or loss.

 

The Company documents at the inception of the hedging transaction the relationship between hedging instruments and hedged items, as well as its risk management objectives and strategy for undertaking the hedge transactions. The Company also documents its assessment, both at hedge inception and on an ongoing basis, whether the derivatives that are used in hedging transactions and accounted for as hedge accounting were, and will continue to be, highly effective in offsetting changes in the fair value or cash flow of hedged items.

 

(i) Cash flow hedge

 

Derivatives that are designated for hedge accounting recognition are qualified as cash flow hedges when they are related to a highly probable forecasted transaction. The effective portion of the changes in fair value is recognized in shareholders’ equity in Accumulated other comprehensive (loss) income and is subsequently reclassified to the income statement in the same period when the hedged expected cash flows affect the income statement.

 

The reclassification adjustment is recognized in the same income statement line item affected by the highly probable forecasted transaction, while gains or losses related to the non-effective portion are immediately recognized as Other income and expenses, net.

 

When a hedging instrument expires, is sold or no longer meets the criteria for hedge accounting, any cumulative gain or loss existing in shareholders’ equity at that time remains in shareholders’ equity and is recognized when the forecast transaction is ultimately recognized in the income statement. When a forecasted transaction is no longer expected to occur, the cumulative gain or loss that was previously accounted in shareholders’ equity is immediately transferred to the income statement within Other income and expenses, net.

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

(ii) Fair value hedge

 

Derivatives that are designated for hedge accounting are qualified as fair value hedges when they are related to assets or liabilities already recognized in the consolidated balance sheet. Changes in the fair values of derivatives that are designated and qualify as fair value hedges and changes in the fair value of the hedged item are recorded in the income statement in the same period.

 

(iii) Derivatives not designated as hedging instruments

 

Changes in the fair value of derivative financial instruments not designated as hedging instruments are recognized immediately in the income statement within Other income and expenses, net when related to price risk and within Net financial results when related to interest rate or foreign exchange rate risk.

 

(a) Fair value by strategy

 

              2020           2019  
Strategy   Per Unit   Notional     Fair value     Notional     Fair value  
Mismatches of quotational periods                                    
Zinc forward   ton     204,394       2,398       258,220       (713 )
                  2,398               (713 )
Sales of zinc at a fixed price                                    
Zinc forward   ton     15,695       1,815       15,252       (1,043 )
                  1,815               (1,043 )
Interest rate risk                                    
LIBOR vs. CDI (i) (ii)   USD     -       -       90,000       (1,413 )
IPCA vs. CDI   BRL     226,880       1,310       226,880       1,482  
                  1,310               69  
Foreign exchange risk                                    
BRL vs. USD (i)   BRL     477,000       (417 )     -       -  
Collars USD vs. BRL (ii)   BRL     -       -       653,148       (607 )
                  (417 )             (607 )
                                     
                  5,106               (2,294 )
Current assets                 16,329               4,835  
Non-current assets                 15,651               14,689  
Current liabilities                 (5,390 )             (8,276 )
Non-current liabilities                 (21,484 )             (13,542 )

 

(i) Related to derivative financial instruments entered into at the same time of certain debt contracts in order to manage some of the risks of such debt contracts. Refer to note 26 (c) for additional information.

 

(ii) These derivatives were used to mitigate the Company’s exposure to the foreign currency risk associated with changes in the Brazilian real exchange rate and were unwound on July 02, 2020.

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

(b)  Changes in fair value

 

Strategy   Inventory     Cost of sales     Net revenues     Other income and expenses, net     Net financial results     Other comprehensive (loss) income     Realized (loss) gain  
Mismatches of quotational
periods
    (568 )     (17,349 )     9,309       1,331       -       (98 )     (10,486 )
Sales of zinc at a fixed price     -       -       -       (383 )     -       -       (3,241 )
Interest rate risk – LIBOR vs. CDI (i)     -       -       -       -       16,981       -       15,568  
Interest rate risk – IPCA vs. CDI     -       -       -       -       786       -       959  
Foreign exchange risk - BRL vs USD (i)     -       -       -       -       (417 )     -       -  
Foreign exchange risk – Collars USD
vs. BRL (ii)
    -       -       -       -       (18,067 )     -       (18,675 )
      (568 )     (17,349 )     9,309       948       (717 )     (98 )     (15,875 )

 

(i) Related to the changes in the fair value of certain derivative financial instruments entered into at the same time of certain debt contracts in order to manage some of the risks of such debt contracts. Refer to note 26 (c) for additional information.

 

(ii) Related to zero cost collars entered into to manage foreign currency risk on the Aripuanã project capital expenditures that were unwound on July 02, 2020, as described above. Losses were driven by the devaluation of the BRL against USD during 2020.

 

41 of 77 

 

 

 

Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

18 Sensitivity analysis

 

Presented below is a sensitivity analysis of the main risk factors that affect the pricing of the outstanding financial instruments relating to cash and cash equivalents, financial investments, loans and financings, and derivative financial instruments. The main sensitivities are the exposure to changes of the US Dollar exchange rate, the London Interbank Offered Rate (LIBOR) and Interbank Deposit Certificate (CDI) interest rates, the US Dollar coupon and the commodity prices. The scenarios for these factors are prepared using market sources and other relevant sources, in compliance with the Company's policies. The scenarios at December 31, 2020 are described below:

 

· Scenario I: considers a change in the market forward yield curves and quotations as of December 31, 2020, according to the base scenario defined by the Company for March 31, 2021.

· Scenario II: considers a change of + or -25% in the market forward yield curves as of December 31, 2020.

· Scenario III: considers a change of + or -50% in the market forward yield curves as of December 31, 2020.

 

                    Impacts on income statement   Impacts on statement of comprehensive income  
                              Scenarios II and III     Scenarios II and III  
Risk factor      Quotation at December 31, 2020      Cash and cash equivalents and financial investments      Loans and financings      Derivative financial instruments      Changes from 2020      Scenario I     -25%   -50%    +25%      +50%      Scenario I     -25%   -50%    +25%      +50%  
Foreign exchange rates                                                                                            
BRL     5.1967     205,466     445,783     892     -0.54 %   537     21,566     43,133     (21,566 )   (43,133 )   229     10,570     21,140     (10,570 )   (21,140 )
EUR     1.2273     3,021     -     -     -3.85 %   (116 )   (755 )   (1,510 )   755     1,510     -     -     -     -     -  
PEN     3.6224     45,890     2,775     -     3.79 %   1,636     (10,779 )   (21,557 )   10,779     21,557     -     -     -     -     -  
CAD     1.2750     1,373     -     -     -1.92 %   -     -     -     -     -     (26 )   (343 )   (687 )   343     687  
NAD     14.6960     1,956     -     -     12.05 %   -     -     -     -     -     236     (489 )   (978 )   489     978  
Interest rates                                                                                            
BRL - CDI     1.90 %   205,407     156,927     892     1 bps     4,085     5,850     12,146     (5,441 )   (10,509 )   -     -     -     -     -  
USD - LIBOR     0.23 %         238,792     3,796     7 bps     (208 )   (246 )   (495 )   243     483     (0 )   (1 )   (2 )   1     2  
Price - commodities                                                                                            
Zinc     2,723     -     -     4,214     -13.71 %   6,321     11,522     23,044     (11,522 )   (23,044 )   (891 )   (1,625 )   (3,249 )   1,625     3,249  

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

19 Trade accounts receivables

 

Accounting policy

 

Trade accounts receivables are amounts due from customers for goods sold in the ordinary course of the Company’s business.

 

Trade accounts receivables are recognized initially at fair value and subsequently measured at:

 

(i) Fair value through profit or loss when are related to the Company’s accounts receivables portfolio that is included in a true sale program whereby the Company, at its discretion, can discount certain outstanding trade accounts receivables and receive payments in advance. The program is used to meet short-term liquidity needs. Trade accounts receivables within this program are derecognized since the contractual rights to receive the cash flows of the assets are transferred to the counterparty.

 

(ii) Fair value through profit or loss when are related to sales that are subsequently adjusted to changes of LME prices. These accounts receivable do not meet the SPPI criteria because there is a component of commodity price risk that modifies the cash flows that otherwise would be required by the sales contract.

 

(iii) Amortized cost using the effective interest rate method, less impairment, when the receivables do not meet the aforementioned classifications.

 

Credit risk can arise from non-performance by counterparties of their contractual obligations to the Company. To ensure an effective evaluation of credit risk, management applies procedures related to the application for credit granting and approvals, renewal of credit limits, continuous monitoring of credit exposure in relation to established limits and events that trigger requirements for secured payment terms. As part of the Company’s process, the credit exposures with all counterparties are regularly monitored and assessed.

 

The Company applies the IFRS 9 simplified approach to measure the impairment losses for trade accounts receivables. This approach requires the use of the lifetime expected credit losses on its trade accounts receivables measured at amortized cost. To calculate the lifetime expected credit losses the Company used a provision matrix and forward-looking information. The additions to impairment of trade accounts receivables are included in selling expenses. Trade accounts receivables are generally written off when there is no expectation of recovering additional cash.

 

(a) Composition

 

    2020     2019  
Trade accounts receivables     229,800       175,948  
Related parties - note 22     2,411       3,620  
Impairment of trade accounts receivables (i)     (3,179 )     (2,337 )
      229,032       177,231  

 

(i) COVID-19 may have changed the risk profile of the Company’s customers, especially those clients that might have transactions, or are located in areas, which are affected, or are more prone to be economically affected. As such risks increase, the Company expects an increase in impairment losses on trade accounts receivables. As of December 31, 2020, the Company has taken an impairment, related to COVID-19, of USD 321 in order to reflect the actual economic scenario and the deterioration in the risk profile of the Company´s clients.

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

(b)  Changes in impairment of trade accounts receivables

 

    2020     2019  
Balance at the beginning of the year     (2,337 )     (2,690 )
Additions     (2,643 )     (805 )
Reversals     1,288       1,085  
Foreign exchange (losses) gains     513       73  
Balance at the end of the year     (3,179 )     (2,337 )

 

(c)  Analysis by currency

 

    2020     2019  
USD     186,420       149,348  
BRL     41,601       26,817  
Other     1,011       1,066  
      229,032       177,231  

 

(d)  Aging of trade accounts receivables

 

    2020     2019  
Current     222,670       150,134  
Up to 3 months past due     6,728       26,810  
From 3 to 6 months past due     102       135  
Over 6 months past due     2,711       2,489  
      232,211       179,568  
Impairment     (3,179 )     (2,337 )
      229,032       177,231  

 

20 Inventory

 

Accounting policy

 

Inventory is stated at the lower of cost and net realizable value. Cost is determined using the weighted average cost method. The cost of finished goods and work in progress comprises raw materials, direct labor, other direct costs and related fixed production overheads (based on normal operating capacity). Variable production overhead costs are included in inventory cost based on the actual production level. The net realizable value is the estimated selling price in the ordinary course of business, less any additional selling expenses. Imports in transit are stated at the accumulated cost of each import. A provision for obsolete inventory - finished products, semi-finished products, raw materials and auxiliary materials - is recognized when items cannot be used in normal production or sold because they are damaged or do not meet the Company’s specification. Slow-moving provision is recognized for inventory items that are in excess of the expected normal use or sale. The amount of slow-moving provision recognized is determined based on 20% of the carrying amount for each six-month period without use or sale.

 

44 of 77 

 

 

 

Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

(a) Composition

  

    2020     2019  
Finished products     94,033       106,595  
Semi-finished products     56,335       89,239  
Raw materials     66,278       50,848  
Auxiliary materials and consumables     68,950       76,974  
Inventory provisions (i)     (29,074 )     (28,398 )
      256,522       295,258  

 

(i) As of December 31, 2020, there was no COVID-19 impact on the Company's inventory costs considering that zinc price increased by the end of the year in comparison with that of December 2019.

 

Due to the lower mining production and smelting production in Peru because of the Peruvian government’s mandates in response to the COVID-19 (as explained in note 1) and also due to the 40% reduction in production at Juiz de Fora smelting unit in Brazil, in May and June, because of the anticipated lower market demand also associated with COVID-19, the Company recognized USD 73,930 in cost of sales related to abnormal production costs in 2020. Idle capacity used to determine the abnormal cost of production was calculated using the historical production data of the actual production during the period this idle capacity was estimated. Since August 2020, the Company determined that there was no longer need to recognize any abnormal production costs since the operating units were returning to their projected production.

 

(b) Changes to the provision of the year

 

    2020     2019  
Balance at the beginning of the year     (28,398 )     (23,437 )
Additions     (11,439 )     (16,171 )
Reversals     9,647       11,077  
Exchange variation gains     1,116       133  
Balance at the end of the year     (29,074 )     (28,398 )

 

21 Other assets

 

    2020     2019  
Other recoverable taxes (i)     127,815       157,008  
Advances to third parties     15,006       19,942  
Prepaid expenses     10,522       11,678  
Judicial deposits     5,566       7,281  
Related parties – note 22     2       744  
Other assets     25,361       45,289  
      184,272       241,942  
Current assets     91,141       103,134  
Non-current assets     93,131       138,808  

 

(i) The Company recognized recoverable PIS and COFINS indirect tax credits in 2018 in the amount of USD 64,454 (equivalent to BRL 243MM) based on a favorable and definitive judicial decision over the exclusion of ICMS on the PIS and COFINS tax base. Federal authorities submitted a position to the Brazilian Supreme Court (“Superior Federal Court - STF”) questioning the timing validity of the credits and their calculation methodology. Future decisions of the STF may result in adjustments to recognized credits, including credits that have already been used to offset other tax debts.

 

45 of 77 

 

  

 

Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

22 Related parties

 

    Trade accounts receivables     Related parties’
assets
    Trade payables     Dividends payable     Related parties’
liabilities
 
Assets and liabilities   2020     2019     2020     2019     2020     2019     2020     2019     2020     2019  
Parent                                                                                
Votorantim S.A. (i)     -       -       2       3       809       517       -       -       -       -  
                                                                                 
Related parties                                                                                
Andrade Gutierrez Engenharia S.A. (ii)     -       -       -       -       1,160       1,415       -       -       -       -  
Companhia Brasileira de Alumínio     1,479       1,812       -       -       175       341       -       -       -       11  
Votorantim Cimentos S.A.     595       1,518       -       738       121       48       -       -       -       -  
Votener - Votorantim Comercializadora de Energia Ltda.     332       290       -       -       6,330       7,172       -       -       -       -  
Votorantim International CSC S.A.C     -       -       -       -       421       500       -       -       -       -  
Other     5       -       -       3       871       1,352       4,557       6,662       561       823  
      2,411       3,620       2       744       9,887       11,345       4,557       6,662       561       834  
                                                                                 
Current     2,411       3,620       -       -       9,887       11,345       4,557       6,662       -       -  
Non-current     -       -       2       744       -       -       -       -       561       834  
      2,411       3,620       2       744       9,887       11,345       4,557       6,662       561       834  

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

    Sales     Purchases  
    2020     2019     2018     2020     2019     2018  
Parent                                                
Votorantim S.A. (i)     -       26       -       4,378       6,176       3,649  
                                                 
Related parties                                                
Andrade Gutierrez Engenharia S.A. (ii)     -       -       -       26,280       5,046       -  
Companhia Brasileira de Alumínio     7,828       2,157       39       1,156       1,964       1,626  
Votorantim Cimentos S.A.     -       196       173       524       2,186       365  
Votener - Votorantim Comercializadora de Energia Ltda.     9,740       3,288       2,115       7,721       9,596       10,054  
Votorantim International CSC S.A.C     -       -       -       6,638       5,584       4,136  
Other     11       510       -       582       1,581       784  
      17,579       6,177       2,327       47,279       32,133       20,614  

 

(i) The Company entered into an agreement with VSA on September 4, 2008, for services provided by the Center of Excellence (“CoE”) of VSA related to administrative activities, human resources, back office, accounting, taxes, technical assistance, and training, among others. Under a cost sharing agreement, the Company reimburses VSA for the expenses related to these activities in respect of the Company.

 

(ii) As part of the execution of the Aripuanã project, in June 2019 the Company entered into a mining development services agreement with Andrade Gutierrez Engenharia S.A., in which one of the Company director’s close family member may have significant influence at its holding level. The updated amount of this contract is USD 52,668 at December 2020. In June 2020, NEXA entered into one additional agreement with Consórcio Construtor Nova Aripuanã (a consortium of the Andrade Gutierrez group of companies) in connection with construction services for the Aripuanã project, in the total amount of USD 21,319.

 

47 of 77 

 

 

 

Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

(a) Key management compensation

 

Key management includes the members of the Company's global executive team and Board of directors. Key management compensation, including all benefits, was as follows:

 

    2020     2019  
Short-term benefits     6,765       6,727  
Other long-term benefits     1,791       660  
      8,556       7,387  

 

Short-term benefits include fixed compensation, payroll charges and short-term benefits under the Company’s variable compensation program. Other long-term benefits relate to the variable compensation program.

 

23 Property, plant and equipment

 

Accounting policy

 

Property, plant and equipment are stated at their historical cost of acquisition or construction less accumulated depreciation and any recognized impairment losses. Historical cost includes expenditures that are directly attributable to the acquisition and construction of the assets.

 

Subsequent costs are included in the asset’s carrying amount, or recognized as a separate asset as appropriate, only when it is probable that future economic benefits associated with the item will flow to the Company and they can be measured reliably. The carrying amount of any component accounted for as a separate asset is derecognized when replaced. All other repairs and maintenance are charged to the income statement during the reporting period in which they are incurred.

 

Replacement costs are included in the carrying amount of the asset when it is probable that the Company will realize future economic benefits in excess of the benefits expected from the asset in its current condition. Replacement costs are depreciated over the remaining useful life of the related asset.

 

Land is not depreciated. Depreciation of other assets is calculated using the straight-line method to reduce their costs to their residual values over their estimated useful lives.

 

The assets' residual values and useful lives are reviewed annually and adjusted if appropriate.

 

An asset's carrying amount is reduced to its recoverable amount when it is greater than the estimated recoverable amount, in accordance with the criteria adopted by the Company in order to determine the recoverable amount.

 

Gains and losses on disposals are determined by comparing the proceeds with the carrying amount and are recognized within Other income and expenses, net in the income statement.

 

Loans and financings costs directly related to the acquisition, construction or production of a qualifying asset that requires a substantial period of time to prepare for its intended use or sale are capitalized as part of the cost of that asset when it is probable that future economic benefits associated with the item will flow to the Company and costs can be measured reliably.

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

Stripping costs

 

In its surface mining operations, the Company must remove overburden and other waste to gain access to mineral ore deposits. The removal process is referred to as stripping. During the development of a mine, before production commences, when the stripping activity improves access to the ore body, the component of the ore body for which access has been improved can be identified and the costs can be measured reliably, a stripping activity asset is capitalized as part of the investment in the construction of the mine and is accounted for as part of Property, plant and equipment within Assets and projects under construction. Subsequently, when the operation starts, the stripping costs are transferred to Buildings and are depreciated by a linear calculation considering the asset’s useful life.

 

Stripping costs incurred during the production phase of operations are treated as production costs and are part of the inventory cost.

 

Mining Projects

 

Refer to note 8 for the Company’s accounting policy related to capitalization of mineral exploration and project evaluation costs for mining projects.

 

Capitalized costs incurred during a project’s exploration and evaluation stages are classified within Mining projects, under Property, plant and equipment and are only depreciated by the units of production (“UoP”) method once the development stage finishes and the project’s operation starts.

 

Costs incurred during a project’s development stage are capitalized under Property, plant, and equipment within Assets and projects under construction. Once the development stage is finished and the project’s operation starts, the capitalized development costs are reclassified to the appropriate group of assets considering their nature and are depreciated on a linear calculation based on the assets’ useful life.

 

Based on the above, once a project begins operation, there will be depreciation coming from the project’s capitalized mineral exploration and evaluation costs within the Mining projects account and based on the UoP method and from the project’s capitalized development costs within the corresponding group of assets based on their useful life.

 

The carrying value of the capitalized exploration and evaluation costs, which remain within Mining projects, and the capitalized development costs, which are within Assets and projects under construction, of the projects are assessed for impairment at least annually or whenever evidence indicates that the assets may be impaired in accordance with IFRS 6 and IAS 36. If the Company decides at any moment to discontinue the project, this could be an impairment indicator that will be assessed under the impairment test. For purposes of this impairment assessment, the projects are allocated to cash-generating units when applicable. The annual impairment test is disclosed in note 33.

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

Asset retirement obligation

 

An asset retirement obligation is an obligation related to the permanent removal from service of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a tangible long-lived asset. At the initial recognition of an asset retirement obligation and at the periodical revisions of the expected disbursements and the discount rate, the changes in the liability are charged to property, plant and equipment.

 

The capitalized amount recognized in property, plant and equipment is depreciated based on the useful life of the underlying asset. Any reduction in the provision that exceeds the carrying amount of the asset, is immediately recognized in the income statement as Other income and expenses, net.

 

Impairment

 

Refer to note 33 for the Company’s accounting policy related to impairment of property, plant and equipment.

 

50 of 77 

 

 

 

 

Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

 

(a) Changes in the year

 

    2020  
      Dam and
buildings
      Machinery,
equipment,
and facilities
      Assets and
projects
under
construction
      Asset
retirement
obligation
      Mining
projects
      Other       Total  
Balance at the beginning of the year                                                        
Cost     1,050,632       2,419,034       549,903       201,892       261,117       45,035       4,527,613  
Accumulated depreciation and impairment     (511,973 )     (1,666,480 )     (14,811 )     (97,233 )     (93,009 )     (21,417 )     (2,404,923 )
Net balance at the beginning of the year     538,659       752,554       535,092       104,659       168,108       23,618       2,122,690  
Additions (i)(ii)     -       3,315       336,457       -       -       935       340,707  
Disposals and write-offs     (240 )     (1,732 )     (662 )     -       -       (42 )     (2,676 )
Depreciation     (48,938 )     (110,515 )     -       (6,096 )     (869 )     (1,261 )     (167,679 )
Impairment of non-current assets - note 33     (45,188 )     (26,521 )     (57,621 )     (13,804 )     (15,805 )     (106 )     (159,045 )
Foreign exchange effects     (60,934 )     (78,038 )     (83,982 )     (12,821 )     (3,852 )     (4,182 )     (243,809 )
Transfers – note 24 (a)     71,244       88,047       (201,752 )     -       36,042       1,770       (4,649 )
Reclassification     -       (916 )     -       -       -       (1,201 )     (2,117 )
Remeasurement of asset retirement obligations     -       -       -       14,874       -       -       14,874  
Balance at the end of the year     454,603       626,194       527,532       86,812       183,624       19,531       1,898,296  
Cost     1,022,432       2,360,426       596,675       211,650       292,322       36,816       4,520,321  
Accumulated depreciation and impairment     (567,829 )     (1,734,232 )     (69,143 )     (124,838 )     (108,698 )     (17,285 )     (2,622,025 )
Balance at the end of the year     454,603       626,194       527,532       86,812       183,624       19,531       1,898,296  
                                                         
Average annual depreciation rates %     4       7       -       5        UoP                  

 

51 of 77 

 

 

 

Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

 

    2019  
    Dam and
buildings
    Machinery,
equipment,
and facilities
    Assets and
projects
under
construction
    Asset
retirement
obligation
    Mining
projects (ii)
    Other     Total  
Balance at the beginning of the year                                                        
Cost     1,002,885       2,357,254       364,476       175,506       243,629       51,142       4,194,892  
Accumulated depreciation and impairment     (452,560 )     (1,554,728 )     (15,407 )     (91,874 )     (86,904 )     (24,968 )     (2,226,441 )
Net balance at the beginning of the year     550,325       802,526       349,069       83,632       156,725       26,174       1,968,451  
Additions (i)(ii)     47       508       410,253       776       1,529       32       413,145  
Disposals and write-offs     (569 )     (2,388 )     (315 )     -       (88 )     (2,833 )     (6,193 )
Depreciation     (50,295 )     (134,092 )     -       (5,971 )     (2,297 )     (1,418 )     (194,073 )
Impairment of non-current assets - note 33     (15,225 )     (27,458 )     -       -       -       -       (42,683 )
Foreign exchange effects     (11,169 )     (13,431 )     (9,801 )     (2,115 )     -       (718 )     (37,234 )
Transfers – note 24 (a)     65,545       129,167       (214,114 )     -       12,239       2,381       (4,782 )
Reclassification - note 25 (a)     -       (2,278 )     -       -       -       -       (2,278 )
Remeasurement of asset retirement obligations     -       -       -       28,337       -       -       28,337  
Balance at the end of the year     538,659       752,554       535,092       104,659       168,108       23,618       2,122,690  
Cost     1,050,632       2,419,034       549,903       201,892       261,117       45,035       4,527,613  
Accumulated depreciation and impairment     (511,973 )     (1,666,480 )     (14,811 )     (97,233 )     (93,009 )     (21,417 )     (2,404,923 )
Balance at the end of the year     538,659       752,554       535,092       104,659       168,108       23,618       2,122,690  
                                                         
Average annual depreciation rates %     4       7       -       5         UoP       -          

 

(i) Additions include capitalized borrowing costs on Assets and projects under construction in the amount of USD 2,023 for the year ended December 31, 2020 (December 31, 2019: USD 8,719).

(ii) Only the amounts related to the operating unit Atacocha are being depreciated under the UoP method.

 

52 of 77 

 

 

 

Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

(b) Impairment of Jarosite project

 

The Company reviewed its portfolio of assets and projects under construction in 2020 and concluded that there are impairment indicators for its Jarosite Project. The execution of this project was suspended and in 2020 studies to conclude its economical and operational viability began and are ongoing. Within this context, the Company used the fair value method to test the Jarosite project for impairment and recorded an impairment loss in the amount of USD 45,220 in 2020. Expenditures related to the project after the aforementioned impairment, if any, will be registered as impairment loss in the income statement.

 

For the impairment calculation, the Company has analyzed each component of the project and classified them as saleable, scrap, or labor expenses directly attributable to the project. Saleable and scrap were evaluated in accordance with the Company’s historical recoverability on sale of assets in accordance with each category, and capitalized labor expenses were written off entirely.

 

(c) Impairment of Ambrosia mine assets

 

The Ambrosia mine is located in Brazil and owned by NEXA BR. Initially, according to its licensing process, the end of life of this mine would be in 2021. However, due to the uncertainties associated with the geological model of the area, safety considerations, and a greater movement of ore compared to the original plan, NEXA anticipated the mine´s closure, and communicated the temporary suspension of Ambrosia’s operational activities to the local environmental agency, during the fourth quarter of 2020. Due to the anticipation of the mine closure and the uncertainties that arise with such decision, the Company reviewed Ambrosia´s portfolio of assets and analyzed the possibility of using these assets in other operations, such as the Bonsucesso mine. However, since this project is still under feasibility studies, the Company decided to recognize an impairment loss in the total amount of USD 10,410 thousand (approximately BRL 55,567 thousand). In the future if the assets were to be used in other mines or projects, the Company will analyze the possible reversal or definitively write-off these assets.

 

24 Intangible assets

 

Accounting policy

 

Goodwill

 

Goodwill arising from business combinations is measured as the excess of the sum of the consideration transferred, the amount of any non-controlling interests in the acquiree, and the fair value of the acquirer’s previously held equity interest in the acquiree (if any) over the net assets acquired. Goodwill is not amortized but is tested for impairment annually and whenever circumstances indicate that the carrying amount may not be recovered. Refer to note 33 for the Company’s impairment accounting policy and critical estimates and judgments.

 

Rights to use natural resources

 

Costs for the acquisition of rights to explore and develop mineral properties are capitalized and are amortized as production costs when the associated projects start their commercial operation using the UoP method over their useful lives. Useful lives consider the period of extraction for both mineral reserves and mineral resources, which includes a portion of the Company’s inferred resources in the Company’s mining operations. The costs for the acquisition of rights attributed to mining projects are not depreciated until the project becomes operational and production activities start.

 

53 of 77 

 

 

 

Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

The costs incurred are impaired if Company determines that the projects and their mineral rights associated have no future economic value. For purposes of impairment assessment, rights to use natural resources are allocated to cash generating units (“CGU”). Refer to note 33 for the Company’s impairment accounting policy.

 

Critical accounting estimates and judgments - Quantification of mineral reserves and resources for useful life calculation

 

The Company classifies proven and probable reserves, and measured, indicated and inferred resources based on the definitions of the Canadian Institute of Mining, Metallurgy and Petroleum (or CIM) Definition Standards for Mineral Resources and Mineral Reserves (or the 2014 CIM Definition Standards).

 

The useful life determination applied to the rights to use natural resources reflect the pattern in which the benefits are expected to be derived by the Company and is based on the estimated life of mine. Any changes to the life of mine, based on new information regarding estimates of mineral reserves and mineral resources and mining plan, may affect prospectively the life of mine and amortization rates.

 

The estimation process of mineral reserves and mineral resources is based on a technical evaluation, which includes geological, geophysics, engineering, environmental, legal and economic estimates and may have relevant impact on the economic viability of the mineral reserves and mineral resources. These estimates are reviewed periodically, and any changes are reflected in the expected life of mine. Management is confident based on testing, continuity of the ore bodies and conversion experience that a part of the inferred resources will be converted into measured and indicated resources, and if they are economically recoverable, and such inferred resources may also be classified as proven and probable mineral reserves. Where the Company can demonstrate the expected economic recovery with a high level of confidence, inferred resources are included in the calculation of amortization.

 

However, the future conversion of inferred resources is inherently uncertain and involves judgment and estimates that could have a material impact on the Company’s results of operations.

 

(a) Changes in the year

 

    2020  
    Goodwill     Rights to use
natural

resources
    Other     Total  
Balance at the beginning of the year                                
Cost     674,645       1,668,956       59,408       2,403,009  
Accumulated amortization and impairment     -       (825,163 )     (39,320 )     (864,483 )
Net balance at the beginning of the year     674,645       843,793       20,088       1,538,526  
Disposals     -       -       (55 )     (55 )
Amortization     -       (60,936 )     (2,842 )     (63,778 )
Impairment of non-current assets - note 33     (267,342 )     (131,110 )     -       (398,452 )
Transfers – note 23 (a)     -       -       4,649       4,649  
Foreign exchange effects     (869 )     (2,877 )     (739 )     (4,485 )
Balance at the end of the year     406,434       648,870       21,101       1,076,405  
Cost     673,776       1,665,149       53,463       2,392,388  
Accumulated amortization and impairment     (267,342 )     (1,016,279 )     (32,362 )     (1,315,983 )
Balance at the end of the year     406,434       648,870       21,101       1,076,405  
                                 
Average annual depreciation rates %     -         UoP       -          

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

    2019  
    Goodwill     Rights to use
natural
resources
    Other     Total  
Balance at the beginning of the year                                
Cost     674,800       1,669,645       56,853       2,401,298  
Accumulated amortization and impairment     -       (620,600 )     (38,237 )     (658,837 )
Net balance at the beginning of the year     674,800       1,049,045       18,616       1,742,461  
Additions     -       -       56       56  
Disposals     -       -       (377 )     (377 )
Amortization     -       (105,262 )     (2,332 )     (107,594 )
Impairment of non-current assets - note 33     -       (99,450 )     -       (99,450 )
Transfers – note 23 (a)     -       -       4,782       4,782  
Foreign exchange effects     (155 )     (541 )     (656 )     (1,352 )
Balance at the end of the year     674,645       843,792       20,089       1,538,526  
Cost     674,645       1,668,956       59,409       2,403,010  
Accumulated amortization and impairment     -       (825,164 )     (39,320 )     (864,484 )
Balance at the end of the year     674,645       843,792       20,089       1,538,526  
                                 
Average annual depreciation rates %     -         UoP       -          

 

25 Right-of-use assets and lease liabilities

 

Accounting policy

 

Right-of-use assets represent the right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease.

 

Lease terms are negotiated on an individual asset basis and contractual provisions contain a wide range of different terms and conditions. The lease agreements do not impose any covenants, but leased assets may not be used as security for borrowing purposes.

 

The Company accounts for non-lease components such as service costs separately, whenever applicable. The Company’s lease terms may include options to extend or terminate the lease and when it is reasonably certain that we will exercise that option, the financial effect is included in the measurement of the contract.

 

Measurement

 

Liabilities arising from a lease contract are initially measured on a present value basis, using the incremental borrowing rate approach. The incremental borrowing rate is determined by the Company based on equivalent financial costs that would be charged by a counterparty for a transaction with the same currency and a similar amount, term and risk of the lease contract. The finance cost charged to the income statement produces a constant periodic rate of interest over the lease term. At December 31, 2020, interest rates were between 5.24% to 11.39% for Brazil and 2.65% to 5.49% for Peru.

 

Lease contracts are recognized as a liability with a corresponding right-of-use asset at the date at which the leased asset is available for use by the Company. The right-of-use asset also includes any lease payments made and it is amortized over the shorter of the asset’s useful life and the lease term on a straight-line basis. Amortization expenses are classified either in Cost of sales or Administrative expenses based on the designation of the related assets.

 

55 of 77 

 

 

Nexa Resources S.A.

 

Notes to the consolidated financial statements 

At and for year ended December 31, 2020 

All amounts in thousands of US dollars, unless otherwise stated

 

 

 

(a) Right-of-use assets - Changes in the year

 

                            2020     2019  
    Buildings     Machinery,
equipment,
and
facilities
    IT
equipment
    Vehicles     Total     Total  
Balance at the beginning of the year                                                
Cost     6,836       10,280       5,846       22,810       45,772       41,521  
Accumulated amortization     (1,569 )     (2,878 )     (3,675 )     (8,103 )     (16,225 )     -  
Net balance at the beginning of the year     5,267       7,402       2,171       14,707       29,547       41,521  
New contracts     329       1,441       -       4,015       5,785       3,517  
Amortization     (1,560 )     (2,821 )     (1,887 )     (6,200 )     (12,468 )     (16,225 )
Reclassification – note 23 (a)     -       -       -       -       -       2,278  
Foreign exchange effects     (704 )     (1,082 )     -       (2,209 )     (3,995 )     (1,544 )
Balance at the end of the year     3,332       4,940       284       10,313       18,869       29,547  
Cost     6,461       10,639       5,846       24,616       47,562       45,772  
Accumulated amortization     (3,129 )     (5,699 )     (5,562 )     (14,303 )     (28,693 )     (16,225 )
Net balance at the end of the year     3,332       4,940       284       10,313       18,869       29,547  
Average annual amortization rates %     25       35       63       39                  

 

(b) Lease liabilities - Changes in the year

 

    2020     2019  
Balance at the  beginning of the year     34,384       41,450  
New contracts     5,785       3,517  
Payments of lease liabilities     (9,100 )     (13,280 )
Interest paid on lease liabilities     (1,385 )     (3,259 )
Interest accrued – note 10     1,757       3,418  
Reclassification     -       3,087  
Foreign exchange effects     (5,752 )     (549 )
Balance at the end of the year     25,689       34,384  
Current liabilities     15,999       16,474  
Non-current liabilities     9,690       17,910  

 

Leasing agreements were assessed by the Company to evaluate any COVID-19 impacts, and no material impacts in the measurement of the liabilities were identified for 2020.

 

26 Loans and financings

 

Accounting policy

 

Loans and financings are recognized initially at fair value, net of transaction costs incurred, and are subsequently measured at amortized cost and designated as fair value option, if necessary. Any difference between the proceeds (net of transaction costs) and the total amount payable is recognized in the income statement as interest expense over the period of the loans using the effective interest rate method, except for the loans measured at fair value.

 

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Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

Loans and financings are classified as current liabilities unless the Company has the unconditional right to defer repayment of the liability for at least 12 months after the reporting period.

 

Fees paid on the establishment of loan facilities are recognized as transaction costs of the loan to the extent that it is probable that some or all of the facility will be drawn down. In this case, the fee is deferred until the drawdown occurs.

 

To the extent that there is no evidence that it is probable that some or all of the facility will be drawn down, the fee is capitalized as a prepayment for liquidity services and amortized over the period of the facility to which it relates.

 

(a) Composition

 

                    2020     2019  
Type   Average interest rate   Current     Non-current     Total     Total  
Eurobonds – USD   Fixed + 5.73 %     22,846       1,316,126       1,338,972       1,043,748  
Export credit notes   LIBOR + 1.54 %
111.55 % CDI
    50,934       183,287       234,221       97,378  
Term loans   LIBOR + 1.27 %
 Fixed + 8.49 %
    47,415       166,320       213,735       197,926  
BNDES   TJLP + 2.82 %
SELIC + 3.10 %
TLP - IPCA + 5.43 %
    9,629       170,199       179,828       95,295  
Debentures   107.5 % CDI     5,224       5,164       10,388       20,265  
Other         9,954       37,216       47,170       53,945  
          146,002       1,878,312       2,024,314       1,508,557  
                                     
Current portion of long-term loans and financings (principal)         61,279                          
Interest on loans and financings         36,652                          

 

(b) Loans and financing transactions during the year ended December 31, 2020

 

On February 24, 2020, the Company completed a tender offer to purchase for cash any and all of its outstanding 2023 Notes. Holders of the 2023 Notes tendered an aggregate principal amount of USD 214,530, or 62.55% of the outstanding principal amount as of the date of the offer. USD 128,470 of the 2023 Notes at a cost of 4.625% p.a. remain outstanding. In the transaction the Company also paid an amount of USD 14,481 related to the premium over the notes, which was recognized in the net financial results. Refer to note 10 for additional information on the effect on income statement.

 

On March 12, 2020, in order to enhance its short-term liquidity, NEXA Peru entered into a term loan with a global financial institution, in the principal amount of BRL 477,000 thousand (approximately USD 100,000) at a cost of 8.5% p.a., with a five-year maturity and an option to prepay before maturity. Simultaneously, the Company contracted a swap to exchange the interest rate to 2.45% p.a. as well as the currency of debt service repayments from BRL to USD. The Company accounted for the term loan under the fair value option to eliminate the accounting mismatch that would arise if amortized cost were used. The term loan is guaranteed by NEXA.

 

At the end of March 2020, in order to enhance its short-term liquidity in Brazil, the Company entered into four export credit note agreements in the total principal amount of BRL 1,247,000 thousand (approximately USD 250,000) at costs between 134.2% of CDI and CDI + 1.80% up to 4.20%, with maturity dates between 1 and 5 years. All these credit notes were obtained from global financial institutions and can be repaid before maturity.

 

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Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

On April 9, 2020, NEXA BR entered into an additional export credit note agreement in the total principal amount of BRL 230,000 thousand, representing USD 45,297 approximately, registered in the date of the received cash, at a cost of CDI + 3.90%, with a one-year maturity. The export credit note is guaranteed by NEXA.

 

On April 14, 2020, in order to enhance its short-term liquidity, the Company fully drew down its revolving credit facility in the amount of USD 300,000.

 

On June 15, 2020, the Company concluded a Bond Offering in the amount of USD 500,000, with a maturity date in January 2028 at an interest rate of 6.50% per year. The interest on the notes will be paid semi-annually commencing on January 18, 2021. The bonds are guaranteed by NEXA BR, NEXA Peru and NEXA CJM. The funds of this new offering were used to prepay three outstanding debts, as follows:

 

a. Export Facility Agreement in the aggregate principal amount of USD 100,000 and USD 246 of accrued interest, on June 19, 2020;

 

b. Revolving Credit Facility in the aggregate principal amount of USD 300,000 and USD 1,348 of accrued interest, on June 23, 2020; and

 

c. Export Credit Note in Brazil in the aggregate principal amount of USD 91,308, USD 4,521 of accrued interest and USD 596 of penalty charge, on June 29, 2020.

 

On July 22, NEXA, through its subsidiary Dardanelos, entered into a new loan agreement with the Brazilian Economic and Social Bank (“BNDES”) of up to BRL 750,000 thousand (approximately USD 140,000) at a cost of TLP (“Taxa a longo prazo” or “Long term rate”) + 3.39%, with a maturity date in 2040. This agreement is guaranteed by NEXA BR and NEXA. The proceeds will be used to finance the ongoing construction of the Aripuanã project. After complying with all the established precedent conditions, the Company obtained the disbursement of the following tranches during the fourth quarter of 2020:

 

a. On October 26, 2020, BRL 225,000 thousand (approximately USD 39,945); and,

 

b. On December 28, 2020, BRL 250,000 thousand (approximately USD 47,719).

 

On October 30, 2020, the Company prepaid the outstanding principal and accrued interest of an Export Credit Note in Brazil in the amount of BRL 230,000 thousand and BRL 887 thousand of accrued interest (approximately USD 45,469).

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

(c) Changes in the year

 

    2020     2019  
Balance at the beginning of the year     1,508,557       1,424,867  
New loans and financings     1,296,496       106,229  
Debt issue costs     (9,921 )     (255 )
Payments of loans and financings     (757,513 )     (19,437 )
Foreign exchange effects     (45,295 )     (7,754 )
Changes in the Company´s credit risk of the financial liability (i)     787       -  
Fair value of loans and financings (i)     8,058       6,640  
Reclassification     -       (3,490 )
Interest accrual     107,532       73,561  
Premium paid on bonds repurchase     (14,481 )     -  
Interest paid on loans and financings     (69,906 )     (71,804 )
Balance at the end of the year     2,024,314       1,508,557  

 

(i) Related to the changes in the fair value of two debt contracts for which the Company elected to apply the fair value option for measurement. The fair value option aims to eliminate the accounting mismatch that would arise if amortized cost were used since such debt contracts have derivative financial instruments contracted to economically modify certain terms of such debt contracts. In the year, the fair value of the relevant derivative financial instruments resulted in a gain in the total amount of USD 16,565. Therefore, in 2020, the net result between the debt contracts and the relevant derivative financial instruments was a gain of USD 8,507 (excluding the effect of changes in the Company´s credit risk of the financial liability in the amount of a loss of USD 787, which is included in other comprehensive (loss) income). Below is a summary of these two debt contracts terms:

 

a. Export Credit Note agreement in the principal amount of USD 90,000, at a cost of three-month Libor + 1.54% p.a., with a five-year maturity. Simultaneously, the Company contracted a swap to exchange the interest index to CDI + 1.30% p.a., as well as the currency of debt service repayments from USD to BRL. However, as mentioned in note 17, this swap was unwound in July, but this debt will still be measured at fair value as initially defined.

 

b. Term loan in the principal amount of BRL 477,000 thousand (approximately USD 100,000) at a cost of 8.5% p.a., with a five-year maturity. Simultaneously, the Company contracted a swap to exchange the interest rate to 2.45% p.a. as well as the currency of debt service repayments from BRL to USD.

 

(d) Maturity profile

 

    2020  
    2021     2022     2023     2024     2025     As from
 2026
    Total  
Eurobonds – USD     22,846       -       124,244       -       -       1,191,882       1,338,972  
Export credit notes     50,934       47,060       -       87,650       48,577       -       234,221  
Term loans     47,415       43,914       23,727       3,542       95,137       -       213,735  
BNDES     9,629       14,834       19,187       19,742       18,795       97,641       179,828  
Debentures     5,224       5,164       -       -       -       -       10,388  
Other     9,955       9,635       8,246       7,737       7,736       3,861       47,170  
      146,003       120,607       175,404       118,671       170,245       1,293,384       2,024,314  

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

(e) Analysis by currency

  

                    2020     2019  
    Current     Non-current     Total     Total  
USD     71,185       1,498,757       1,569,942       1,389,462  
BRL     74,034       377,600       451,634       119,095  
Other     783       1,955       2,738       -  
      146,002       1,878,312       2,024,314       1,508,557  

 

(f) Analysis by index

 

                2020     2019  
    Current     Non-current     Total     Total  
Fixed rate     31,300       1,424,790       1,456,090       1,044,564  
LIBOR     48,120       182,454       230,574       345,601  
TLP     6,201       126,079       132,280       53,712  
BNDES SELIC     2,170       28,513       30,683       25,970  
CDI     55,899       100,784       156,683       20,265  
TJLP     2,270       15,692       17,962       18,333  
Other     42       -       42       112  
      146,002       1,878,312       2,024,314       1,508,557  

 

(g) Guarantees and covenants

 

The Company has loans and financings that are subject to certain financial covenants at the consolidated level, such as: (i) leverage ratio; (ii) capitalization ratio; and (iii) debt service coverage ratio. When applicable, these compliance obligations are standardized for all debt agreements. No changes to the contractual guarantees occurred in year ended December 31, 2020. Before the end of June 30, 2020, waiver agreements were concluded as explained below.

 

The financial covenants are measured annually and semiannually, as required by the debt contracts, and given the impact of the COVID-19 on the Company’s financial situation as of June 30, 2020, the Company obtained waivers in respect of its Leverage Ratio as of June 30, 2020 and as of December 31, 2020 and repaid certain of its debts with Leverage Ratio covenants. NEXA will not be required to measure its Leverage Ratio Covenant until June 30, 2021. These waivers were negotiated in anticipation of a possible breach of the Leverage Ratio at the end of June and December 2020, and the Company paid waiver fees in the amount of USD 2,234. As of December 31, 2020, the Company was in compliance of all its financial covenants.

 

27 Trade Payables

 

Accounting policy

 

Trade payables represent liabilities for goods and services that were provided to the Company before the end of the financial year which are unpaid. Trade and other payables are presented as current liabilities unless payment is not due within 12 months after the reporting period. These amounts are recognized initially at their fair value and subsequently measured at amortized cost using the effective interest method.

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

  

(a) Composition

 

    2020     2019  
Trade payables     360,235       402,735  
Related parties – note 22     9,887       11,345  
      370,122       414,080  

 

28 Asset retirement and environmental obligations

 

Accounting policy

 

Provision is made for asset retirement obligations, restoration and environmental costs when the liability arises due to the development or mineral production of an operating asset, based on the net present value of estimated closure costs. Management uses its judgment and previous experience to determine the potential scope of rehabilitation work required and the related costs associated with that work.

 

The cash flows are discounted to present value using a credit risk-adjusted rate that reflects current market assessments of the time value of the money and the specifics risks for the asset to be restored. The interest rate charges relating to the liability are recognized as an accretion expense in the Net financial results. Difference in the settlement amount of the liability are recognized in the income statement.

 

Critical accounting estimates and judgments

 

The initial recognition and the subsequent revisions of the asset retirement obligations consider critical future closure costs estimates and several assumptions such as interest rates, inflation and useful lives of the assets. These estimates are reviewed quarterly by the Company.

 

Cost estimates can vary in response to many factors of each site that include timing, expected life of mine, changes to the relevant legal or government requirements and commitments with stakeholders, review of remediation and relinquishment options, emergence of new restoration techniques, among others.

 

External experts support the cost estimation process where appropriate. These factors either isolated or consolidated could significantly affect the future financial results and balance sheet position.

 

(a) Changes in the year

 

                2020     2019  
    Asset
retirement
obligations
    Environmental
obligations
    Total     Total  
Balance at the beginning of the year     222,377       71,451       293,828       270,283  
Additions     -       -       -       777  
Payments     (3,350 )     (7,076 )     (11,132 )     (14,550 )
Foreign exchange effects     (21,613 )     (15,532 )     (37,145 )     (4,301 )
Interest accrual     10,889       3,126       14,015       13,425  
Remeasurement discount rate (i)     17,379       (3,112 )     14,973       (3,635 )
Changes in amount and time of cash flows (ii)     1,507       -       1,507       31,828  
Balance at the end of the year     227,189       48,857       276,046       293,827  
Current liabilities     24,510       8,585       33,095       19,001  
Non-current liabilities     202,679       40,272       242,951       274,826  

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 
 

 

(i) As of December 31, 2020, the credit risk-adjusted rate used for Peru was between 1.70% to 4.00% (December 31, 2019: 5.2% to 7.8%) and for Brazil was between 0.07% to 6.75% (December 31, 2019: 3.5% to 5.3%).

 

(ii) In 2019, as part of its annual asset retirement obligations review, the Company increased its expectation of disbursements on decommissioning obligations in certain operations, in accordance with updates in its environmental or asset retirement studies. Property, plant and equipment has been increased by the same amount in accordance with the update of asset retirement studies of the year ended December 31, 2019. For the year ended December 31, 2020, there were no updated environmental studies.

 

29 Provisions

 

Accounting policy

 

Provisions for legal claims and judicial deposits

 

Provisions for legal claims are recognized when: (i) the Company has a present legal or constructive obligation as a result of past events; (ii) it is probable that an outflow of resources will be required to settle the obligation; and (iii) the amount can be reliably estimated. The provisions are periodically estimated, and the likelihood of losses is supported by the Company's legal counsel.

 

Provisions are measured at the present value of the expenditure expected to be required to settle the obligation using a discount rate that reflects current market assessments of the time value of money and the risks specific to the obligation. The increase in the provision due to the passage of time is recognized as Financial expenses.

 

When a claim is secured by a judicial deposit, the Company offsets the provision with the judicial deposit amount in the consolidated balance sheet. However, the Company also has judicial deposits for claims for which the likelihood of loss is possible or remote and for which no provision is recognized. In such cases, these amounts are recognized as outstanding judicial deposits in the Company’s assets.

 

Critical accounting estimates – Provisions for legal claims

 

The Company is part of ongoing labor, civil, tax and environmental lawsuits which are pending at different court levels. The provisions for potentially unfavorable outcomes of litigation in progress are established and updated based on management evaluation, as supported by the positions of external legal counsel, and require a high level of judgment regarding the matters involved. Income tax claims are discussed at the current and deferred income tax section (note 11).

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 
 

 

(a)            Changes in the year

 

                            2020     2019  
    Tax     Labor     Civil     Environmental     Total     Total  
Balance at the beginning of the year     7,747       13,779       1,061       3,483       26,070       30,641  
Additions     1,373       12,204       13       10,462       24,052       12,012  
Reversals     (1,972 )     (6,566 )     -       (4,602 )     (13,140 )     (8,833 )
Interest accrual     242       1,307       34       (194 )     1,389       2,048  
Payments     (150 )     (1,564 )     (7 )     -       (1,721 )     (5,263 )
Foreign exchange effects     (1,364 )     (3,065 )     (238 )     (480 )     (5,147 )     1,104  
Impact of the adoption of IFRIC 23     -       -       -       -       -       (6,047 )
Settlements with escrow deposits     -       (468 )     -       -       (468 )     -  
Other     358       (419 )     (78 )     -       (139 )     409  
Balance at the end of the year     6,234       15,208       785       8,669       30,896       26,071  

 

(b)            Breakdown of legal claims provisions

 

The provisions and the corresponding judicial deposits are as follows:

 

                2020                 2019  
    Judicial deposits     Provisions     Carrying amount     Judicial deposits     Provisions     Carrying amount  
Tax     (1,594 )     7,828       6,234       (2,449 )     10,197       7,748  
Labor     (2,797 )     18,005       15,208       (3,071 )     16,850       13,779  
Civil     (722 )     1,507       785       (832 )     1,893       1,061  
Environmental     -       8,669       8,669       -       3,483       3,483  
Balance at the end of the year     (5,113 )     36,009       30,896       (6,352 )     32,423       26,071  

 

The outstanding judicial deposits of the Company as of December 31, 2020 are USD 5,566 (December 31, 2019: USD 7,281).

 

Contingent liabilities

 

Legal claims that have a possible likelihood that an obligation will arise are disclosed in the Company’s financial statement. The Company does not recognize a liability because it is not probable that an outflow of resources will be required or because the amount of the liability cannot be reliably calculated.

 

(c)            Summary of contingent liabilities

 

The Company is a party to other litigation involving a risk of possible loss, for which no provision has been recognized, as detailed below:

 

      2020     2019  
Tax       182,380       196,031  
Labor       33,205       39,918  
Civil       17,502       21,549  
Environmental       85,390       112,920  
      318,477       370,418  

 

Contingent liabilities decreased in 2020, mainly because the BRL devaluation against the USD during the year.

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 
 

 

(i) Comments on contingent tax liabilities

 

The main contingent liabilities relating to tax lawsuits are discussed below.

 

Income tax over transfers of shares in Peru

 

Relates to assessments issued by the Peruvian internal revenue services, where the Company was jointly and severally liable for the payment of income tax by a foreign investor, in a supposed capital gain on transfer of shares. The estimated financial effect of this contingent liability is USD 95,957.

 

Compensation for exploration for mineral resources

 

Relates to assessments issued by the Brazilian National Department of Mineral Production for the alleged failure to pay or underpayment of financial compensation for the exploration of mineral resources (“CFEM”). The estimated financial effect of this contingent liability is USD 12,797.

 

Indirect taxes on sales

 

Relates to assessments issued by the Brazilian Internal Revenues Service concerning certain credits taken by the Company when calculating those indirect taxes on sales. The estimated financial effect of this contingent liability is USD 4,447.

 

Value-added tax on sales

 

Relates to assessments issued by the tax authorities of the State of Minas Gerais concerning the following:

 

· Incidence of value-added tax on sales of certain energy contracts. The estimated financial effect of this contingent liability is USD 12,954.

 

· The tax rate applied to interstate sales for manufactured goods with imported content. The estimated financial effect of this contingent liability is USD 3,235.

 

· The Company was challenged by the tax authorities regarding certain credits to the purchases of property, plant and equipment. The estimated financial effect of this contingent liability is USD 5,243.

 

(ii) Comments on contingent labor liabilities

 

Include several claims filed by former employees, third parties and labor unions, mostly claiming the payment of indemnities on dismissals, health hazard premiums and hazardous duty premiums, overtime and commuting hours, as well as indemnity claims by former employees and third parties based on alleged occupational illnesses and work accidents. The individual amount of the claims are not material.

 

(iii) Comments on contingent civil liabilities

 

The main contingent civil liability is related to indemnity lawsuits against the Company alleging property damage, pain and suffering. The estimated financial effect of this contingent liability is USD 16,418.

 

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Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 
 

 

(iv) Comments on contingent environmental liabilities

 

The main contingent environmental liabilities were filed by fishermen communities against the Company for indemnification, compensation for material and moral damages due to alleged pollution of the São Francisco River near the Company’s Três Marias operation in Brazil. The estimated financial effect of these contingent liabilities is USD 71,388.

 

30 Contractual obligations

 

Accounting policy

 

Contractual obligations consist of advance payments received by the Company under a silver streaming agreement, signed with a counterparty (the Streamer) and by which referential silver contents found in the ore concentrates sold by the Company are sold to the Streamer.

 

Determining the accounting treatment of silver streaming transactions requires the exercise of high degree of judgment.

 

The Company assesses whether those advances obtained under this agreement should be recognized as contractual obligations (a sale of a non-financial item) or a financial liability. For that purpose, the Company takes into consideration factors such as which party is exposed to the operational risk, the risk of access to the resources, the price risk, and assesses whether the transaction involves a sale of an own use asset for the counterparty. In those cases, in which the Company concludes that, in essence, the Streamer shares substantially the operational risks, the resource access and price risks, it delivers a non-financial item that qualifies as an “own use” item; any advance payment obtained is recognized as a contractual obligation in the framework of IFRS 15: Revenue from contracts with customers. Otherwise, the Company would recognize a financial liability in the framework of the provisions of IFRS 9: Financial instruments.

 

When a contractual obligation is recognized, the balance is initially recognized at the amount received, and it is subsequently recognized as revenue when the control of the respective assets is transferred, that is, upon physical delivery of the nonfinancial item (silver certificate). Contractual obligations are recognized within non-current liabilities, except for the portion of silver certificates that are estimated to be delivered over the 12 months following the balance sheet date.

 

The advance payment obtained under the silver streaming transaction entered by the Company in 2016 is recognized as contractual obligation to the extent that the risk assessment conducted by the management indicates the relevant risks are substantially shared with the Streamer and the qualifying conditions of a sale of an “own use” item are met.

 

Determination of the transaction price

 

The transaction price is the amount of consideration to which the Company expects to be entitled in return for transferring the promised goods to its counterparty. The price transaction is allocated to each performance obligation based on the relative standalone selling prices. In the silver streaming transaction, the Company has variable consideration related to the production capacity of the mine linked to the Life of Mine and London Metal Exchange (LME). IFRS 15 requires that for contracts containing variable consideration, the transaction price be continually updated and re-allocated to the transferred goods. For this purpose, the contractual obligations require an adjustment to the transaction price per unit each time there is a change in the underlying production profile of a mine. The change in the transaction price per unit results in a retroactive adjustment to revenues in the period in which the change is made, reflecting the new production profile expected to be delivered under the streaming agreement. A corresponding retroactive adjustment is made to accretion expenses, reflecting the impact of the change in the contractual obligation balance.

 

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Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 
 

 

Critical accounting estimates and judgments

 

The recognition of revenues and of the contractual obligation related to the silver transaction require the use of critical accounting estimates including, but not limited to: (i) allocation of revenues on relative prices; (ii) estimative prices for determine the upfront payment; (iii) discount rates used to measure the present value of future inflows and outflows (iv) estimative of life of mine, reserves and mineral production.

 

(a) Composition

 

In 2016, the Company entered a silver streaming arrangement, which consisted of an upfront payment of USD 250,000 for the anticipated sale of a portion of the silver contained in the ore concentrates produced by the Cerro Lindo mining unit. The advance payment was recognized as a Contractual obligation and the corresponding revenues are recognized as the silver is delivered, which is the time that the contractual performance obligations are satisfied.

 

The changes in the contractual obligation are shown below:

 

    2020     2019  
Balance at the beginning of the year     180,522       199,637  
Revenues recognition upon ore delivery     (28,492 )     (25,660 )
Remeasurement of revenues based on new reserves (i)     7,813       -  
Accretion for the year     6,182       6,545  
Balance at the end of year     166,025       180,522  
Current     27,132       26,351  
Non-current     138,893       154,171  

 

(i) As of December 31, 2020, the Company recognized a retroactive adjustment in its silver streaming revenues given new reserves identified in Cerro Lindo since according to its accounting policy, changes in life of mine are a variable consideration.

 

31 Confirming Payables

 

Accounting policy

 

The Company enters into contracts with some suppliers to extend the commercial payment term to 180 days. In these contracts, the suppliers have the option to request the bank to advance the payment of their commercial invoice within 180 days, before the invoice matures. As a result of those contracts between the suppliers and the bank, the commercial terms agreed with the Company do not change. In accordance with the commercial agreement, the supplier communicates the Company its interest in selling the invoice to the bank, and it is only the supplier who can decide to sell its invoice at any time during the commercial period. With this option, suppliers could improve their working capital position. The bank pays the supplier with an interest discount and the Company assumes part of the interest payment to the supplier given the negotiation to extend the commercial payment term to 180 days.

 

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Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

As of December 31, 2020, accounts payable of USD 145,295 were included in these contracts (December 31, 2019: USD 82,770; December 31, 2018: USD 70,411).

 

32 Shareholders’ equity

 

Accounting policy

 

Common shares are classified in shareholders’ equity. Each time a share premium is paid to the Company for an issued share, the respective share premium is allocated to the share premium account. Each time the repayment of a share premium is decided, such repayment shall be done pro-rata to the existing shareholders.

 

The distribution of dividends to the Company’s shareholders is recognized as a liability in the Company’s consolidated financial statements in the period in which the dividends are approved by the Company’s shareholders.

 

Shares repurchased under the Company’s buyback program and that are not cancelled, are reported as treasury shares and are deducted from shareholders’ equity. These shares are also deducted in the earnings per share calculation.

 

(a) Capital

 

As of December 31, 2020, the outstanding capital of USD 132,439 (2019: 133,320) is comprised of 132,439 thousand subscribed and issued common shares (2019: 133,320 thousand), with par value of US$ 1.00 per share. In addition to the subscribed and issued common shares, NEXA also has an authorized, but unissued and unsubscribed share capital set at USD 231,925.

 

(b) Treasury shares

 

On September 20, 2018, the Company’s Board of Directors approved a share buyback program to repurchase up to USD 30,000 of its outstanding common shares, over the 12-month period beginning on November 6, 2018 and ending on November 6, 2019. The repurchased shares were not cancelled but held in treasury at that time. As of December 31, 2019, the Company had repurchased USD 9,435, corresponding to 881,902 shares.

 

On June 4, 2020, at NEXA’s Extraordinary General Meeting (“EGM”), the shareholders of the Company approved the cancellation of the 881,902 shares held in treasury, previously repurchased as explained above. For this reason, after the cancellation shares occurred on June 4, 2020, VSA holds 64.68% of NEXA’s equity.

 

(c) Share premium

 

The share premium, if any, may be distributed to the shareholders in accordance with Luxembourg Commercial Companies Act by a resolution of the Board of Directors.

 

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Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

(d) Additional paid in capital

 

Additional paid in capital arises from transactions recognized in equity that do not qualify as capital or share premium in accordance with Luxembourg Commercial Companies Act and, therefore, cannot be distributed to the shareholders of the Company.

 

(e) Accumulated other comprehensive (loss) income

 

The changes in the accumulated other comprehensive (loss) income are as follows:

 

    Cumulative
translation
adjustment
    Hedge
accounting
    Changes in
fair value of
financial
liabilities
    Total  
At January 01, 2018     (99,829 )     2,576       -       (97,253 )
Translation adjustment on foreign investments     (9,959 )     -       -       (9,959 )
Cash flow hedge accounting     -       (2,192 )     -       (2,192 )
At December 31, 2018     (109,788 )     384       -       (109,404 )
Translation adjustment on foreign investments note 3 (Revision)     (21,115 )     -       -       (21,115 )
Cash flow hedge accounting     -       879       -       879  
At December 31, 2019     (130,903 )     1,263       -       (129,640 )
Translation adjustment on foreign investments     (138,840 )     -       -       (138,840 )
Cash flow hedge accounting     -       3       -       3  
Changes in fair value of financial liabilities that relate to changes in the Company’s own credit risk     -       -       (875 )     (875 )
At December 31, 2020     (269,743 )     1,266       (875 )     (269,352 )
Attributable to NEXA's shareholders                             (229,491 )
Attributable to non-controlling interests                             (39,861 )

 

(f) Earnings per share

 

Basic earnings per share are computed by dividing the net income attributable to the NEXA’s shareholders by the average number of outstanding shares for the year. Diluted earnings per share is computed in a similar way, but with the adjustment in the denominator when assuming the conversion of all shares that may be dilutive. The Company does not have any dilutive shares and consequently the basic and diluted earnings per share are the same.

 

    2020     2019     2018  
Net (loss) income for the year attributable to NEXA's shareholders     (559,247 )     (145,135 )     77,026  
Weighted average number of outstanding common shares – in thousands     132,439       132,622       133,313  
Basic and diluted (losses) earnings per share – USD     (4.22 )     (1.09 )     0.58  

 

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Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

(g) Karmin acquisition agreement

 

The Company, through its subsidiary Votorantim Metals Canada Inc., acquired Karmin Exploration Inc. (“Karmin”), a public company listed on the TSX Venture Exchange (Canada) and the Lima Stock Exchange (Peru), for an aggregate acquisition price of USD 70,000. Karmin indirectly held the minority 30.0% interest of Dardanelos, owner of the Aripuanã project, not otherwise owned by the Company. On October 16, 2019, the transaction was approved by Karmin’s shareholders and it closed on October 30, 2019, when the articles of arrangement were filed and the aggregate consideration was paid.

 

The acquisition price contemplated (i) the acquisition of 89,945,479 common shares, representing 100% of the issued and outstanding shares of Karmin, for an aggregate consideration of USD 69,300 paid at closing date to the shareholders of Karmin, and (ii) a USD 700 loan from the Company to Karmin for general corporate purposes.

 

On November 1 and 4, 2019, Karmin delisted its shares from the TSX Venture Exchange and the Lima Stock Exchange, respectively. At the date of the delisting, the Company owned 100% of the outstanding Karmin shares. On November 5, 2019 Votorantim Metals Canada Inc. and Karmin were amalgamated and Karmin ceased to exist.

 

The transaction was accounted for as a transaction with non-controlling interests, as the Company already controlled Dardanelos at the acquisition date. An amount of USD 71,054 related to the difference between the transaction’s acquisition price and the carrying amount of the non-controlling interest held prior to the acquisition was recognized in equity attributable to the NEXA’s shareholders.

 

(h) Acquisition and transfer of the 7.7% participation in the Aripuanã Project between subsidiaries

 

On April 28, 2020, the Board of Directors of NEXA Peru approved the sale of this company’s participation in Dardanelos at a USD 17,970 market value, corresponding to its 7.7% interest in the Aripuanã project, to NEXA BR. After the acquisition executed in 2019 of a third party’s 30% non-controlling interest in the Aripuanã Project, this transfer between NEXA Peru and NEXA BR consolidated the project’s ownership in NEXA BR, NEXA’s principal wholly owned subsidiary in Brazil. This sale, which was concluded in June, had no effect on NEXA’s consolidated financial statements.

 

(i) Decrease in the subscribed capital from Pollarix

 

On April 22, 2020, NEXA’s subsidiary Pollarix reduced proportionally its subscribed capital in the amount, to be paid to its shareholders, of BRL 110,000 thousand (USD 20,057), of which BRL 73,334 thousand (USD 13,392) were related to non-controlling interests owned by VGE, a related party. By the end of 2020, Pollarix had completely paid this capital reduction to its shareholders.

 

(j) Dividend distribution

 

On March 16, 2020 the Company paid dividends for USD 50,000 (USD 0.377533 per common share) to its shareholders, determined based on NEXA’s standalone statutory accounts prepared under Luxembourg GAAP. Additionally, during the second quarter, the Company’s subsidiary Pollarix declared and paid dividends in the amount of USD 5,332 to non-controlling interests owned by Votorantim Geração de Energia S.A. (“VGE”) which is a related party and USD 2,133 to NEXA.

 

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Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

(k) Non-controlling interests

 

    NEXA Peru     Pollarix  
Summarized balance sheet   2020     2019     2020     2019  
Current assets     590,948       725,103       16,902       24,365  
Current liabilities     233,710       237,369       12,936       15,058  
Current net assets     357,238       487,734       3,966       9,307  
                                 
Non-current assets     615,290       695,712       56,049       125,335  
Non-current liabilities     535,838       602,357       18,773       35,872  
Non-current net assets     79,452       93,355       37,276       89,463  
                                 
Net assets     436,690       581,089       41,242       98,770  
                                 
Accumulated non-controlling interests     201,964       313,818       41,835       65,846  

 

    NEXA Peru     Pollarix  
Summarized income statement   2020     2019     2020     2019  
Net revenues     541,099       745,181       67,793       83,597  
Net (loss) income for the year     (138,824 )     11,370       25,960       50,350  
Other comprehensive (loss) income     (5,575 )     -       (11,252 )     1,552  
Total comprehensive (loss) income for the year     (144,399 )     11,370       14,708       51,902  
                                 
Comprehensive (loss) income attributable to non-controlling interests     (25,087 )     (6,918 )     (84,999 )     1,619  
Dividends paid to non-controlling interests     -       30,427       5,332       10,867  

 

    NEXA Peru     Pollarix  
Summarized statement of cash flows   2020     2019     2020     2019  
Net cash (used in) provided by operating activities     29,949       43,341       (13,552 )     (55,426 )
Net cash (used in) provided by investing activities     (47,462 )     (111,268 )     (1,560 )     36,152  
Net cash (used in) provided by financing activities     (113,415 )     (200,248 )     6,147       9,564  
Increase in cash and cash equivalents     (130,928 )     (268,175 )     (8,965 )     (9,710 )

 

33 Impairment of non-current assets

 

Accounting policy

 

Impairment of goodwill

 

As part of the impairment testing procedures, the goodwill arising from a business combination is allocated to a CGU or groups of CGUs that are expected to benefit from the related business combination and is tested at the lowest level that goodwill is monitored by management. Goodwill is tested annually for impairment as of September 30, regardless of whether there has been an impairment indicator or, more frequently, if circumstances indicate that the carrying amount may not be recovered.

 

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Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

Impairment of non-financial assets

 

The Company assesses at each reporting date, whether there are indicators that the carrying amount of an asset or CGU, including goodwill balance, may not be recovered. If any indicator exists, such as a change in forecasted commodity prices, a significant increase in operational costs, a significant decrease in production volumes, a reduction in life of mine, the cancelation or significant reduction in the scope of a project, market conditions or unusual events that can affect the business, the Company estimates the recoverable amount of the assets or CGUs.

 

The recoverable amount is estimated by reference to the higher of an asset’s or CGU’s fair value less cost of disposal (“FVLCD”) and its value in use (“VIU”). The recoverable amount is determined for an individual asset unless the asset does not generate cash inflows that are largely independent of those from other assets or groups of assets, in which case, the asset is tested as part of a larger CGU to which it belongs.

 

If the carrying amount of an asset or CGU exceeds its recoverable amount, the asset or CGU is considered impaired and is reduced to its recoverable amount. Non-financial assets other than goodwill that were adjusted due to impairment are subsequently reviewed for possible reversal of the impairment at each reporting date. Generally, the opposite of indicators that gave rise to an impairment loss would be considered indicators that impairment losses might have to be reversed. If the underlying reasons for the original impairment have been removed or the service potential of the asset or CGU has increased, an assessment of impairment reversals is performed by the Company. Reversals of impairment losses that arise simply from the passage of time are not recognized.

 

Impairment of exploration and evaluation costs and development projects costs

 

Exploration assets representing mineral rights acquired in business combinations, mineral rights, and other capitalized exploration and evaluation costs in accordance with the accounting policy described in note 8, as well as development projects costs capitalized included in Property, plant and equipment are tested for impairment in aggregation with CGU or groups of CGUs that include producing assets or tested individually through FVLCD when there are indicators that capitalized costs might not be recoverable. The allocation of exploration and evaluation costs, and development projects costs to CGUs or group of CGUs is based on 1) expected synergies or share of producing assets infrastructure, 2) legal entity level, and 3) country level. When testing a CGU or a group of CGUs that include exploration and evaluation costs and development projects costs, the Company performs the impairment test in two steps. In the first step, producing assets our group of producing assets are tested for impairment on an individual basis. In the second step, exploration and evaluation costs and development projects costs are allocated to a CGU or a group of CGUs and tested for impairment on a combined basis.

 

Valuation methods and assumptions for recoverable amount based on FVLCD

 

FVLCD

 

FVLCD is an estimate of the price that the Company would receive to sell an asset, CGU or group of CGUs in an orderly transaction between market participants at the measurement date, less the cost of disposal. FVLCD is not an entity-specific measurement but is focused on market participants’ assumptions for a particular asset. FVLCD is estimated by the Company using discounted cash flows techniques and, although the Company considers observable inputs, a substantial portion of the assumptions used in the calculations are unobservable. These cash flows are classified as level 3 in the fair value hierarchy. No CGUs are currently assessed for impairment by reference to a recoverable amount based on FVLCD classified as level 1 or level 2.

 

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Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

VIU

 

VIU is determined as the present value of the estimated future cash flows expected to arise from the continued use of the asset in its current condition and its residual value. VIU is determined by applying assumptions specific to the Company’s continued use and does not consider enhancements or future developments. These assumptions are different from those used in calculating FVLCD and consequently the VIU calculation is likely to give a different result (usually lower) than a FVLCD calculation.

 

Forecast assumptions

 

The cash flow forecasts are based on management’s best estimates of expected future revenues and costs, including the future cash costs of production, capital expenditure, and closure, restoration, and environmental costs. The resulting estimates are based on detailed life of mine and long-term production plans. When calculating FVLCD, these forecasts include anticipated expansions (greenfield projects), considering their evaluation, eventual change in their scope or feasibility, and the development stage.

 

The cash flow forecasts may include net cash flows expected to be realized from the extraction, processing and sale of material that does not currently qualify for inclusion in ore reserves. Such non-reserve material is only included when the Company has confidence it will be converted to reserves. This expectation is usually based on preliminary drilling and sampling of areas of mineralization that are contiguous with existing ore reserves, as well as on the historical internal conversion ratio. Typically, the additional evaluation required for conversion to reserves of such material has not yet been done because this would involve incurring evaluation costs earlier than is required for the efficient planning and operation of the producing mine.

 

For purposes of determining FVLCD from a market participant’s perspective, the cash flows incorporate management’s internal price forecasts. The internal price forecasts are developed using a robust model that incorporates market-based supply, demand and cost data. The internal price forecasts used for ore reserve estimation testing and the Company’s strategic planning are generally consistent with those used for the impairment testing.

 

Cost levels incorporated in the cash flow forecasts are based on the current life of mine plan and long-term production plan for the CGU, which are based on detailed research, analysis and iterative modeling to optimize the level of return from investment, output and sequence of extraction. The mine plan takes into account all relevant characteristics of the orebody, including waste-to-ore ratios, ore grades, haul distances, chemical and metallurgical properties of the ore, process recoveries and capacities of processing equipment that can be used. The life of mine plan and long-term production plans are, therefore, the basis for forecasting production output and production costs in each future year.

 

The discount rates applied to the future cash flow forecasts represent the Company’s estimate of the rate that a market participant would apply to have regard to the time value of money and the risks specific to the asset for which the future cash flow estimates have not been adjusted. The Company’s weighted average cost of capital is generally used for determining the discount rates, with appropriate adjustments for the risk profile of the countries in which the individual CGUs operate.

 

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Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

With respect to the estimated future cash flows of capitalized exploration assets and development projects, the Company applies a price to net assets value ratio discount in order to reflect the inherent risk of such projects and that are neither adjusted in the discount rate nor in the future cash flows.

 

The discount is based on the stage of the project and the type of metal.

 

The cash flow forecasts were adjusted to reflect the potential impacts of the COVID-19 outbreak on the Company and the future projections and operational decisions of management.

 

Critical accounting estimates and judgments - Impairment of non-current assets

 

Impairment is assessed at the CGU level. A CGU is the smallest identifiable asset or group of assets that generates independent cash inflows. Judgment is applied to identify the Company’s CGUs, particularly when assets belong to integrated operations, and changes in CGUs could impact impairment charges and reversals. When applying its judgment in grouping CGUs, the Company concluded that its mining operations in Vazante and Morro Agudo should be grouped with its Três Marias smelter operation, as these two mines are vertically integrated operations with the smelter. Also, the Company concluded that the Shalipayco greenfield project should be grouped with the Cerro Pasco CGU as the current plan, as determined in the scoping study of the project, is to integrate Shalipayco into the Cerro Pasco complex.

 

External and internal factors are quarterly monitored for impairment indicators. Judgment is required to determine, for example, whether the impact of adverse spot commodity price movements is significant and structural in nature. Also, the Company’s assessment of whether internal factors such as an increase in production costs and delays in projects result in impairment indicators require significant judgment. Among others, the long-term zinc price and the discount rate may have a significant impact in the Company’s’ impairment estimations.

 

The process of estimating the recoverable amount involves the use of assumptions, judgment and projections for future cash flows. These calculations use cash flow projections, based on approved financial and operational budgets for a five-year period. After the five-year period, the cash flows are extended until the end of the useful life of mine or indefinitely for the smelters. The smelters cash flows do not use growth rates in the cash flow projections of the terminal value. Management’s assumptions and estimates of future cash flow used for the Company’s impairment testing of goodwill and non-financial assets are subject to risk and uncertainties, including metal prices and macroeconomic conditions, which are particularly volatile and partially or totally outside the Company’s control. Future changes in these variables may differ from management’s expectations and may materially change the recoverable amounts of the CGUs.

 

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Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

 

Impairment analysis

 

On March 31, 2020, the Company identified impairment indicators that arose mainly as a result of the decrease in short- and mid-term commodities prices, suspension of production, discontinued projects and increased operating costs. On September 30, 2020, the Company performed its annual impairment test for the CGUs to which goodwill has been previously allocated (Cerro de Pasco, Cerro Lindo and Cajamarquilla) and given that the Company assessed that there were new impairment indicators, the Company expanded the scope of this test to include all of NEXA’s CGUs. This impairment indicators were the decrease in the market long term zinc price, which is assessed by the Company as part of the strategic planning process which is performed during the third quarter of every year as well as a result of the higher CAPEX to be invested in the Cerro de Pasco CGU.

 

The two impairment assessments made during the year as explained above, resulted in impairment of non-current assets charges of USD 225,633 in the Cerro Pasco CGU and of USD 267,342 in the Mining Peru - goodwill. In addition to this economic impairment, the Company registered individual assets impairment for: (i) USD 45,220 in relation to the Jarosite project (for more information please refer to note 23 (b)); (ii) USD 10,410 in relation to the Ambrosia mining assets (for more information please refer to note 23 (c)); USD 10,055 in relation to Atacocha underground assets (for more information please refer to note 1); and, USD 1,162 related to the reversal of the impairment of other specific assets. In this way, the total recognized impairment of the year was of USD 557,497 (after-tax USD 485,692). The Company, as of December 31, 2020, performed an additional impairment assessment and did not identify any impairment indicator as of this date.

 

As of December 2019, mainly because of the substantial decline in short-term zinc prices in the spot market, a reduction in the life of mine of Cerro Pasco operations due to a decrease in mineral reserves and resources estimates and the persistent carrying amounts of the net assets of the Company being above the market value, the Company’s management considered that these indicators could have a material impact on the CGUs recoverable amounts. After the Company impairment assessment, an economic impairment of USD 142,133 regarding Cerro Pasco CGU was identified.

 

Both impairment results are shown in the Table below:

 

Impairment losses

CGUs or Group of CGUs

  2020     2019     2018  
Cerro Pasco (i)     225,633       142,133       -  
Cerro Lindo (i)     -       -       -  
Mining Peru – goodwill (ii)     267,342       -       -  
Cajamarquilla     -       -       -  
Três Marias System (iii)     -       -       -  
Juiz de fora     -       -       -  
      492,975       142,133       -  

 

(i) Includes exploration assets and development projects with capitalized mining rights and development costs allocated.

(ii) Represents the lowest level within the Company at which the goodwill generated in the acquisition of NEXA Peru is monitored.

(iii) Currently Três Marias smelter is integrated with the operations of Vazante and Morro Agudo and, therefore, are considered as a single CGU.

 

(a) Key assumptions used in impairment test

 

The recoverable amount for each CGU was determined based on the FVLCD method, which was higher than the VIU.

 

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Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

 

The Company identified long term metal prices, discount rate and life of mine (“LOM”) as key assumptions for the recoverable amount determination, due to the material impact such assumptions may cause on the recoverable value. These assumptions are summarized below:

 

    2020     2019     2018  
Long-term zinc (USD/t)     2,449       2,571       2,517  
Discount rate (Brazil)     7.82 %     7.10 %     7.13 %
Discount rate (Peru)     7.22 %     6.38 %     6.30 %
Brownfield projects - LOM (years)     from 5 to 17       from 8 to 13       from 9 to 21  
Greenfield projects - LOM (years)     from 12 to 18       from 12 to 24       from 12 to 24  

 

(b) Impairment loss

 

(i) Cerro Pasco CGU

 

As explained above, an impairment loss was identified at the CGU level and since it is not directly related to a single asset, the loss was allocated in a pro rata basis to the following assets:

 

Impairment loss   2020     2019  
Property, plant and equipment     94,523       42,683  
Intangible assets     131,110       99,450  
      225,633       142,133  

 

The Company performed a stress test on the key assumptions used for the calculation of the recoverable amount of the CGU Cerro Pasco. A decrease of 5% in the long-term LME zinc price to USD 2,326 per ton compared to management´s estimation as of December 31, 2020 would have had resulted in the recognition of an impairment loss of USD 275,447 (or an additional impairment of USD 49,814 in the CGU Cerro Pasco). Also, an increase of 5% in discount rate compared to management´s estimation as of December 31, 2020 would have had resulted in an impairment loss of USD 234,775 (or an additional impairment of USD 9,142 in the CGU Cerro Pasco).

 

(ii) Mining Peru Group of CGU - Goodwill – Breakdown between non-current assets classes and stress test

 

Before the impairment of goodwill recognized during 2020, the CGU Mining Peru had a goodwill in the amount of USD 578,280. After this impairment, assigned to Intangible assets, the goodwill’s balance is of USD 310,938.

 

Impairment loss   2020     2019  
Property, plant and equipment     -       -  
Intangible assets     267,342       -  
      267,342       -  

 

Given the impairment indicators identified in March, an impairment analysis was performed during this month, recognizing an impairment loss of USD 267,342. In September, the annual impairment test was performed and based on the analysis made, no additional impairment was required. No impairment indicators were identified after the annual test made in September. This CGU has a headroom of USD 35,229 or 3.2% of its carrying amount.

 

75 of 77 

 

 

 

Nexa Resources S.A.

 

Notes to the consolidated financial statements

At and for year ended December 31, 2020

All amounts in thousands of US dollars, unless otherwise stated

 

 

 

(c) Impairment results – Other CGUs

 

The impairment indicators identified, led to a decrease in the recoverable amount of all the Company’s CGUs. However, the effects were less prominent than in the CGU Cerro Pasco and Mining Peru and no impairment loss were identified in other CGUs.

 

The Company also estimated the amount by which the value assigned to each of these key assumptions must change in order for the CGUs recoverable amount to be equal to their carrying amount:

 

Cash generating unit   Excess over
carrying
amount
    Decrease in long term
zinc (USD/t)
    Increase in
discount rate
 
      Change     Price     Change     Rate  
Cerro Lindo     346,167       (47 )%     1,298       65 %     11.90 %
Cajamarquilla     101,689       (4 )%     2,354       11 %     8.00 %
Três Marias system     1,137,525       (38 )%     1,518       284 %     30.00 %
Juiz de fora     589,646       (55 )%     1,102       479 %     45.30 %
Aripuanã     412,143       (34 )%     1,616       90 %     14.90 %
Goodwill – Mining Peru     35,229       (5 )%     2,330       5 %     7.60 %

 

34 Long-term commitments

 

(a) Capital commitments – Aripuanã project

 

At December 31, 2020, the Company had contracted USD 156,893 (December 31, 2019: USD 211,259) of capital expenditures related to the Aripuanã project for the purchase of property, plant and equipment that had not been incurred yet.

 

(b) Projects evaluation

 

As part of NEXA’s activities for the execution of certain greenfield projects, the Company has agreed, with the Peruvian Government, to minimum investments levels in the Magistral Project, that if the Company does not meet by September 2024, would require additional disbursements of USD 102,900 as a penalty for the non-execution of the agreed levels.

 

35 Events after the reporting period

 

(a) Prepaid Export Credit Note

 

On January 22, 2021, the Company prepaid the outstanding principal and accrued interest of an Export Credit Note in Brazil in the amount of BRL 250,000 thousand and BRL 12,905 thousand of accrued interest (approximately USD 51,105).

 

76 of 77 

 

 

(b) Dividends distribution

 

On February 11, 2021, the Company’s Board of Directors approved, subject to ratification by the

 

Company’s shareholders at the 2022 annual shareholders’ meeting in accordance with Luxembourg laws, a cash dividend distribution to the Company’s shareholders of record on March 12, 2021 of approximately USD 35,000 to be paid on March 26, 2021.

 

*.*.*

 

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Management’s report on internal control over financial reporting

 

Our management is responsible for establishing and maintaining adequate internal control over financial reporting and for assessing its effectiveness.

 

Our internal control over financial reporting is a process designed by, or under the supervision of, our chief executive officer and our chief financial officer, and effected by our board of directors, management and other employees, and is designed to provide reasonable assurance regarding the reliability of financial reporting and of preparation of our consolidated financial statements, in accordance with IFRS as issued by the IASB.

 

Due to its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. In addition, projections of any evaluation of effectiveness of internal control over financial reporting to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with our policies or procedures may deteriorate.

 

Our management has assessed the effectiveness of internal control over financial reporting as of December, 31, 2020, based upon the criteria established in Internal Controls – Integrated Framework (2013), issued by the Committee of Sponsoring Organizations of Treadway Commission (COSO). Based on this assessment and criteria, our management has concluded that our internal control over financial reporting was effective as of December 31, 2020.

  

Audit of the effectiveness of internal control over financial reporting

 

Our independent registered public accounting firm, PricewaterhouseCoopers Auditores Independentes, has audited the effectiveness of internal control over financial reporting, as stated in their report as of December 31, 2020.

 

Changes in internal control over financial reporting

 

In 2020, the Company implemented additional procedures to improve controls over movements in the translation reserve and additional paid in capital accounts within shareholders’ equity.

 

Also in 2020, the Company implemented automated procedures to replace manual controls over the tax basis of fixed assets at one of the Company’s subsidiaries and improve controls to calculate the deferred tax effects of temporary differences on depreciation of those fixed assets.

 

There were no other changes in our internal control over financial reporting during 2020, which have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

 

Sincerely,

 

Nexa Resources S.A.

 

/s/ Tito Botelho Martins Junior   /s/ Rodrigo Nazareth Menck
Tito Botelho Martins Junior   Rodrigo Nazareth Menck
President and Chief Executive Officer   Chief Financial Officer

 

 

 

 

 

Report of Independent Registered Public Accounting Firm

 

To the Board of Directors and Shareholders

 

Opinions on the Financial Statements and Internal Control over Financial Reporting

 

We have audited the accompanying consolidated balance sheets of Nexa Resources S.A. and its subsidiaries (the “Company”) as of December 31, 2020 and 2019, and the related consolidated income statement, consolidated statement of comprehensive income, consolidated statement of changes in shareholders’ equity and consolidated statement of cash flows for each of the three years in the period ended December 31, 2020, including the related notes (collectively referred to as the “consolidated financial statements”). We also have audited the Company’s internal control over financial reporting as of December 31, 2020, based on criteria established in Internal Control - Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO).

 

In our opinion, the consolidated financial statements referred to above present fairly, in all material respects, the financial position of the Company as of December 31, 2020 and 2019, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2020 in conformity with International Financial Reporting Standards as issued by the International Accounting Standards Board. Also in our opinion, the Company maintained, in all material respects, effective internal control over financial reporting as of December 31, 2020, based on criteria established in Internal Control - Integrated Framework (2013) issued by the COSO.

 

Changes in Accounting Principles

 

As discussed in Note 5 to the consolidated financial statements, the Company changed the manner in which it accounts for leases and the manner in which it accounts for uncertainty over income tax treatments in 2019.

 

Basis for Opinions

 

The Company's management is responsible for these consolidated financial statements, for maintaining effective internal control over financial reporting, and for its assessment of the effectiveness of internal control over financial reporting, included in the Management's Report on Internal Control over Financial Reporting appearing under Item 15. Our responsibility is to express opinions on the Company’s consolidated financial statements and on the Company's internal control over financial reporting based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) ("PCAOB") and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

 

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audits to obtain reasonable assurance about whether the consolidated financial statements are free of material misstatement, whether due to error or fraud, and whether effective internal control over financial reporting was maintained in all material respects.

 

Our audits of the consolidated financial statements included performing procedures to assess the risks of material misstatement of the consolidated financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the consolidated financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the consolidated financial statements. Our audit of internal control over financial reporting included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weakness exists, and testing and evaluating the design and operating effectiveness of internal control based on the assessed risk. Our audits also included performing such other procedures as we considered necessary in the circumstances. We believe that our audits provide a reasonable basis for our opinions.

 

 

 

 

 

Definition and Limitations of Internal Control over Financial Reporting

 

A company’s internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. A company’s internal control over financial reporting includes those policies and procedures that (i) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the company; (ii) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles, and that receipts and expenditures of the company are being made only in accordance with authorizations of management and directors of the company; and (iii) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of the company’s assets that could have a material effect on the financial statements.

 

Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

 

Critical Audit Matters

 

The critical audit matters communicated below are matters arising from the current period audit of the consolidated financial statements that were communicated or required to be communicated to the audit committee and that (i) relate to accounts or disclosures that are material to the consolidated financial statements and (ii) involved our especially challenging, subjective, or complex judgments. The communication of critical audit matters does not alter in any way our opinion on the consolidated financial statements, taken as a whole, and we are not, by communicating the critical audit matters below, providing separate opinions on the critical audit matters or on the accounts or disclosures to which they relate.

 

Impairment Assessment – Cash-Generating Units (“CGUs”)

 

As described in Note 33 to the consolidated financial statements, in 2020 the Company carried out impairment assessments in connection with identified indicators of impairment in all CGUs, resulting in impairment charges of $ 225,633 in Cerro Pasco CGU and of $ 267,342 in the goodwill related to Mining Peru Group of CGU. Potential impairment is identified by comparing the recoverable amount to its carrying amount, including goodwill where applicable. The recoverable amount is the higher of fair value less costs of disposal and value in use. Management estimated the fair value less cost of disposal using a discounted cash flow model. Management’s cash flow projections for each Cash-Generating Unit included significant judgments and assumptions related to long-term metal prices, discount rate and life of mine.

 

The principal consideration for our determination that performing procedures relating to impairment assessment of Cash-Generating Units is a critical audit matter are there was significant judgment by management when developing the recoverable amount of the Cash-Generating Units. This in turn led to a high degree of auditor judgment, subjectivity, and effort in performing procedures to evaluate management’s cash flow projections and significant assumptions, related long-term metal prices, discount rate and life of mine. In addition, the audit effort involved the use of professionals with specialized skill and knowledge to assist in performing these procedures and evaluating the audit evidence obtained.

 

Addressing the matter involved performing procedures and evaluating audit evidence in connection with forming our overall opinion on the consolidated financial statements. These procedures included testing the effectiveness of controls relating to management’s impairment assessment, including controls over the valuation of the Company’s Cash-Generating Units. These procedures also included, among others, testing management’s process for developing the recoverable amount; evaluating the appropriateness of the discounted cash flow model; testing the completeness and accuracy, of underlying data used in the model; and evaluating the significant assumptions used by management, related to the long-term metal prices, discount rate and life of mine. Evaluating management’s assumptions related to long-term metal prices, discount rate and life of mine involved evaluating whether the assumptions used by management were reasonable considering (i) the current and past performance of the Cash-Generating Units, (ii) the consistency with external market and industry data, and (iii) whether these assumptions were consistent with evidence obtained in other areas of the audit. Professionals with specialized skill and knowledge were used to assist in the evaluation of the Company’s discounted cash flow model and certain significant assumptions, including the discount rate.

 

 

 

 

 

Assessment of recoverability of deferred income tax assets

 

As described in Note 11 to the consolidated financial statements, as of December 31, 2020, the Company had deferred income tax assets of $ 221,580 thousand, arising from temporary differences and net operating losses. Deferred tax assets are recognized only to the extent it is probable that future taxable income will be available against which the temporary differences and/or tax losses can be utilized.

 

The principal considerations for our determination that performing procedures relating to the assessment of recoverability of deferred tax assets is a critical audit matter are there was significant judgment by management when developing their projection of recoverability of deferred tax assets. This in turn led to a high degree of auditor judgment and effort in evaluating audit evidence relating to the future taxable income for the utilization of these assets. In addition, the audit effort involved the use of professionals with specialized skill and knowledge to assist in performing these procedures and evaluating the audit evidence obtained.

 

Addressing the matter involved performing procedures and evaluating audit evidence in connection with forming our overall opinion on the financial statements. These procedures included testing the effectiveness of controls that address the risks of material misstatement relating to the recoverability of deferred tax assets, including controls over management’s projections of future taxable income. These procedures also included, among others, testing management’s process for developing the projections of future taxable income by income tax jurisdiction, tested the completeness and accuracy of the underlying data used in the projections, tested the appropriateness of the recoverability assessment model and tested the key assumptions used by management in the projection of recoverability of deferred tax assets. Professionals with specialized skill and knowledge were used to assist in the evaluation of the Company’s future tax model and certain significant assumptions related to the long-term metal prices.

 

/s/ PricewaterhouseCoopers Auditores Independentes

Curitiba, Brazil

February 11, 2021

 

We have served as the Company’s auditor since 2001.

 

 

 

 

 

 

 

Exhibit 1

 

Nexa Resources S.A.

 

Société anonyme

 

37A, Avenue J.F. Kennedy

 

L-1855 Luxembourg

 

Grand Duchy of Luxembourg

 

R.C.S. Luxembourg: B 185.489 

 

 

ARTICLES OF ASSOCIATION AS OF 4 JUNE 2020

 

 

 

TITLE I - DENOMINATION, REGISTERED OFFICE, OBJECT, DURATION

 

1. ARTICLE 1.-

 

There is hereby established a public limited liability company (“société anonyme”) under the name of “Nexa Resources S.A.” (the “Company”) governed by the present articles of association (the “Articles”) and by current Luxembourg law (“Luxembourg Law”), in particular the law of 10 August 1915 on commercial companies, as amended (the “Commercial Companies Law”).

 

2. ARTICLE 2.-

 

2.1 The Company has its registered office in the City of Luxembourg, Grand Duchy of Luxembourg.

 

2.2 The registered office may be transferred within the Grand Duchy of Luxembourg by decision of the board of directors of the Company (the “Board of Directors”). The Board of Directors is authorised to amend these Articles to reflect the change of registered office and to proceed to such formalities as may be required under Luxembourg Law.

 

2.3 The registered office of the Company may be transferred outside the Grand Duchy of Luxembourg by means of a resolution of the shareholders adopted at a general meeting of shareholders of the Company (the “General Meeting”) under the conditions required by these Articles.

 

2.4 The Company may have offices and branches (whether or not a permanent establishment) both in Luxembourg and abroad.

 

2.5 In the event that the Board of Directors should determine that extraordinary political, economic or social developments have occurred or are imminent that would interfere with the normal activities of the Company at its registered office or with the ease of communication between such office and persons abroad, the registered office may be temporarily transferred abroad until the complete cessation of these extraordinary circumstances; such temporary measures shall have no effect on the nationality of the Company which, notwithstanding the temporary transfer of its registered office, will remain a Luxembourg company. Such temporary measures will be taken and notified to any interested parties by the Board of Directors.

 1

 

3. ARTICLE 3.-

 

The Company is established for an unlimited period of time.

 

4. ARTICLE 4.-

 

The Company’s purpose is:

 

1) To carry out any trade, business or commercial activities whatsoever, including but not limited to the purchase, exchange and sale of goods and/or services to third parties;

 

2) To take participations and interests, in any form whatsoever, in any commercial, industrial, financial or other, Luxembourg or foreign companies or enterprises;

 

3) To acquire through participations, contributions, underwriting, purchases or options, negotiation or in any other way any securities, rights, patents and licenses and other property, rights and interest in property as the Company shall deem fit;

 

4) Generally to hold, manage, develop, sell or dispose of the same, in whole or in part, for such consideration as the Company may think fit, and in particular for shares or securities of any company purchasing the same;

 

5) To enter into, assist or participate in financial, commercial and other transactions;

 

6) To grant to any holding company, subsidiary, or fellow subsidiary, or any other company which belong to the same group of companies as the Company (the “Affiliates”) any assistance, loans, advances or guarantees (in the latter case, even in favour of a third-party lender of the Affiliates);

 

7) To borrow and raise money in any manner and to secure the repayment of any money borrowed; and

 

8) Generally to do all such other things as may appear to the Company to be incidental or conducive to the attainment of the above objects or any of them.

 

The Company can perform all commercial, technical and financial operations, connected directly or indirectly in all areas as described above in order to facilitate the accomplishment of its purpose, provided always that the Company will not enter into any transaction which would constitute a regulated activity of the financial sector without due authorisation under Luxembourg Law.

 2

 

TITLE II - CAPITAL, SHARES

 

5. ARTICLE 5.

 

5.1 The subscribed share capital is set at USD 132,438,611 (one hundred thirty-two million four hundred thirty eight six hundred eleven United States Dollars) divided into 132,438,611 (one hundred thirty-two million four hundred thirty eight six hundred eleven) shares having a nominal value of USD 1 (one United States Dollar) each (the “Shares”).

 

5.2 The Shares can only be in registered form.

 

5.3 The Company may, without limitation, accept equity or other contributions without issuing Shares or other securities in consideration for the contribution and may credit the contributions to one or more accounts. Decisions as to the use of any such accounts are to be taken by the Board of Directors subject to the Commercial Companies Law and these Articles. For the avoidance of doubt, any such decision may, but needs not to, allocate any amount contributed to the contributor.

 

5.4 The subscribed share capital and any Authorised Capital (as defined below) may be increased or reduced by a resolution of the General Meeting adopted in accordance with the conditions required for the amendment of the Articles, as further detailed in Article 13.18.2 and in accordance with Luxembourg Law.

 

5.5 All Shares must be fully paid up on issue by contributions in cash or in kind.

 

5.6 The Company may have a sole shareholder. The death or dissolution of a sole shareholder will not result in the dissolution of the Company.

 

5.7 In addition to its issued and subscribed share capital, the Company has also an authorised, but unissued and unsubscribed share capital set at USD 231,924,819 (two hundred thirty-one million nine hundred twenty-four thousand eight hundred nineteen United States Dollars) (the “Authorised Capital”).

 

5.8 The Board of Directors is authorised, during a period starting on the day of the general meeting of shareholders held on 4 June 2020 and ending on the fifth anniversary of the date of publication in the Luxembourg legal gazette (Recueil Electronique des Sociétés et Associations) of the minutes of such general meeting, without prejudice to any renewals, to increase the issued share capital on one or more occasions within the limits of the Authorised Capital.

 

5.9 The Board of Directors is authorized to determine the conditions of any capital increase and the issuance of new Shares and the instruments to be issued in accordance with the above provisions through contributions in cash or in kind, among others, by the conversion of debt into equity, by offsetting receivables, by the incorporation of reserves, issue premiums or retained earnings, with or without the issue of new Shares, or following the issue and the exercise of subordinated or non-subordinated bonds, convertible into or repayable by or exchangeable for Shares (whether provided in the terms at issue or subsequently provided), or following the issue of bonds with warrants or other rights to subscribe for Shares attached, or through the issue of stand-alone warrants or any other instrument carrying an entitlement to, or the right to subscribe for, Shares.

 3

 

 

5.10 The Board of Directors may approve the issuance of new Shares and, where applicable, the instruments to be issued in accordance with the provisions of this Article 5 of the present Articles without reserving (i.e. by cancelling or limiting) the preferential right to subscribe for such Shares and instruments for the existing shareholders so long as such issuance of new Shares and instruments is carried out through a public offering process.

 

5.11 The Board of Directors is authorized to set the subscription price, with or without issue premium, the date from which the Shares or other financial instruments will carry beneficial rights and, if applicable, the duration, amortization, other rights (including early repayment), interest rates, conversion rates and exchange rates of the aforesaid financial instruments as well as all the other conditions and terms of such financial instruments including as to their subscription, issue and payment, for which the Board of Directors may decide that, if the proposed increase of capital is not entirely subscribed for, the capital shall be increased by the amount of subscriptions received.

 

5.12 The Board of Directors is authorized, subject to performance criteria, to allocate existing Shares or new Shares issued under the Authorized Capital free of charge, to employees and corporate officers (including directors) of the Company and of companies of which at least 10 per cent of the capital or voting rights is directly or indirectly held by the Company. The terms and conditions of such allocations are to be determined by the Board of Directors.

 

5.13 When the Board of Directors has implemented a complete or partial increase in capital as authorized by the foregoing provisions, Article 5 of the present Articles shall be amended to reflect that increase.

 

5.14 The Board of Directors is expressly authorized to delegate to any natural or legal person to organize the market in subscription rights, accept subscriptions, conversions or exchanges, receive payment for the price of Shares, bonds, subscription rights or other financial instruments, to have registered increases of capital carried out as well as the corresponding amendments to Article 5 of the present Articles and to have recorded in said Article 5 of the present Articles the amount by which the authorization to increase the capital has actually been used and, where appropriate, the amounts of any such increase that are reserved for financial instruments which may carry an entitlement to Shares. The non-subscribed portion of the Authorized Capital may be drawn on by the exercise of conversion or subscription rights already conferred by the Company.

 

5.15 The Company may, to the extent and under the terms permitted by Luxembourg Law, purchase its own Shares or cause them to be repurchased by its subsidiaries.

 

5.16 The Company shall consider the person in whose name the Shares are recorded in the register of shareholders to be the owner of those Shares.

 

5.17 Only if a public offering of Shares on a stock exchange, either regulated or not, in the European Economic Area, the United Kingdom, the United States of America, or Canada occurred and in case Shares are recorded in the register of shareholders on behalf of one or more persons in the name of a securities settlement system or the operator of such a system or in the name of a professional depositary of securities or any other depositary (such systems, professionals or other depositaries being referred to hereinafter as “Depositaries”) or of a sub-depositary designated by one or more Depositaries, the Company—subject to a confirmation in proper form received from the Depositary—will permit those persons to exercise the rights attaching to those Shares, including admission to and voting at General Meetings. The Board of Directors may determine the requirements which such confirmations must comply with.

 4

 

5.18 Confirmations that an entry has been made in the register of shareholders will be provided to shareholders directly recorded in the register of shareholders or, in case of Depositaries or sub-depositaries recorded in the register, upon their request. Except for transfers in accordance with the rules and regulations of the relevant Depositary, the transfer of Shares shall be made by a written declaration of transfer recorded in the register of shareholders and dated and signed by the transferor and the transferee or by their duly-appointed agents. The Company may accept any other document, instrument, writing or correspondence as sufficient proof of the transfer.

 

TITLE III - MANAGEMENT

 

6. ARTICLE 6.-

 

6.1 The Company shall be managed by a board of directors comprising at least five (5) members and a maximum of eleven (11) members (each a “Director” and together the “Directors”), who shall be appointed by the General Meeting in accordance with Article 13.18.1. The Board of Directors shall at all times be composed as required pursuant to applicable law, including, if applicable, the rules and regulations of any stock exchange on which part or all of the Shares of the Company are listed. In particular, at least three (3) Directors shall meet the independence and financial literacy requirements for audit committee members set forth in the listing rules of the New York Stock Exchange, Toronto Stock Exchange, or any stock exchange on which any Shares of the Company are then listed and any additional requirements under the rules and regulations of the U.S. Securities and Exchange Commission, Canadian securities laws and other applicable law, subject to any available exemptions.

 

6.2 The Directors, whether shareholders or not, are appointed for a period not exceeding one (1) year (renewable) by the General Meeting, which may at any time and “ad nutum” remove them.

 

6.3 The number of Directors and the overall remuneration of the Board of Directors are determined by the General Meeting. The Board of Directors determines the remuneration of each Director based on the total amount determined by the General Meeting.

 

6.4 Any Director may resign at any time by delivering his or her resignation in writing or by electronic transmission to the Chairman (as defined below) or to the Board of Directors. Such resignation shall be effective upon receipt by the Company unless it is specified therein to be effective at some later time, and the acceptance of a resignation shall not be necessary to make it effective unless such resignation specifies otherwise.

 

6.5 In the event that a Director appointed by the General Meeting ceases to be a Director for any reason, the remaining Directors, by a simple majority vote of the Directors present or represented, shall fill such vacancy by replacing such Director with a new Director nominated for appointment in place thereof. This Director will be in office up to the next General Meeting taking place.

 5

 

6.6 Any Director may be suspended or dismissed at any time by a resolution of the General Meeting adopted at a simple majority.

 

7. ARTICLE 7.-

 

7.1 The Board of Directors shall elect from its members a chairman (the “Chairman”) and who may choose a secretary for each meeting, who need not be a director and who shall be responsible for keeping the minutes of such meeting of the Board of Directors. The Chairman will preside at all meetings of the Board of Directors. In his absence, the other members of the Board of Directors will appoint another chairman “pro tempore”, by simple majority vote of the Directors present or represented at such meeting, who will preside at the relevant meeting.

 

7.2 The Board of Directors is convened upon call by the Chairman or at least three (3) Directors, as often as the interest of the Company so requires, and at least once every quarter during each accounting year unless otherwise agreed in writing by the Board of Directors.

 

7.3 No separate notice is required for meetings held at times and places specified in a schedule previously adopted by a resolution of the Board of Directors.

 

7.4 Any director may act at any meeting of the Board of Directors by appointing in writing, whether in original, by mail or email, another Director as his or her proxy. A Director may represent more than one of his or her colleagues, provided that at least two (2) directors are present in person or participate by telephone conference or similar means in any meeting.

 

7.5 The Board of Directors can validly debate and take decisions only if at least the majority of its members is present or represented. Resolutions of the Board of Directors are only validly adopted if carried by a majority of the votes of the members of the Board of Directors present or represented. In case of a tie vote, the matter shall be deferred by the Chairman.

 

7.6 Directors may participate in a meeting of the Board of Directors by means of telephone conference or similar communications equipment allowing the identification of each participating Director and by means of which all persons participating in the meeting can hear and speak to each other on a continuous basis, and such participation in a meeting will constitute presence in person at the meeting, provided that all actions approved by the Directors at any such meeting will be reproduced in writing in the form of resolutions.

 

7.7 The deliberations of the Board of Directors shall be recorded in the minutes, shall be signed by the Chairman and by the secretary of the meeting or a member of the Board of Directors who participated to the meeting. Any transcript of or excerpt from these minutes shall be signed by the Chairman or by the secretary of such meeting.

 6

 

7.8 Resolutions in writing signed by all members of the Board of Directors will be as valid and effective as if passed at a meeting duly convened and held. The signatures of such resolutions may appear on a single document or multiple counterparts of an identical document and may be evidenced by mail, email or any similar means. Resolutions adopted in accordance with this procedure are deemed to have been taken at the registered office of the Company.

 

7.9 The Board of Directors shall approve the internal regulation of the Board of Directors.

 

8. ARTICLE 8.-

 

8.1 The Board of Directors is vested with the powers to perform all acts of administration and disposition in compliance with the corporate object of the Company, with the exception of the powers reserved by Luxembourg Law or by the Articles to the General Meeting.

 

8.2 The Board of Directors may establish and dissolve committees including, but not limited to, an audit committee, a compensation, nominating and governance committee, a finance committee, and a sustainability committee set forth their respective duties, approve the internal regulations of those committees, elect the respective members thereof and define and approve, based on the total amount determined by the General Meeting, the remuneration of the members of such committees, including as required pursuant to applicable law (including the rules and regulations of any stock exchange applicable to the Company). Such committee members shall exercise their duties under the responsibility of the Board of Directors.

 

9. ARTICLE 9.-

 

9.1 The Company is validly bound or represented towards third parties by:

 

9.1.1 the joint signature of two (2) Directors;

 

9.1.2 if the Board of Directors of the Company has delegated certain powers to a Management Committee (as defined in Article 10), by the joint signature of two (2) Managing Officers, but only within the limits of such delegated powers;

 

9.1.3 if a sole Daily Manager (as defined in Article 11.1) has been appointed, the Company will be bound by the sole signature of such Daily Manager to the extent powers have been delegated to him under Article 11.1, but only within the limits of such delegated powers;

 

9.1.4 if more than one Daily Manager as defined in Article 11.1 has been appointed, the Company will be bound by the joint signature of two Daily Managers, to the extent powers have been delegated to them under Article 11.1, but only within the limits of such delegated powers; or

 

9.1.5 the sole signature or joint signature of any other person(s) to whom such a power has been delegated in accordance with Article 11.2, but only within the limits of such delegated powers.

 7

 

10. ARTICLE 10.-

 

10.1 The Board of Directors may delegate its powers to conduct the management and affairs of the Company, except the general guidance of the Company’s business and the acts reserved by the Commercial Companies Law to the Board of Directors, and the representation of the Company for such management and affairs to a management committee (the “Management Committee”) comprising at least three (3) members and a maximum of eleven (11) members, who need not be shareholders or Directors (each a “Managing Officer”).

 

10.2 The Managing Officers are appointed by the Board of Directors of the Company for a period not exceeding one (1) year (renewable) which may at any time and “ad nutum” remove and replace them. Their remuneration is determined by the Board of Directors.

 

10.3 The Board of Directors shall approve the internal regulations of the Management Committee and set forth its duties.

 

10.4 Without prejudice to the general management powers of the Board of Directors set forth in Article 8.1, if a Management Committee is established, such Management Committee will in particular be in charge of the following matters:

 

10.4.1 generally all acts or transactions involving the Company with an individual amount of up to USD 100,000,000.00 (one hundred million United States Dollars);

 

10.4.2 appointment and removal of the Daily Managers (as defined below); and

 

10.4.3 any other specific tasks that may be conferred to the Management Committee by the Board of Directors as determined in the relevant resolution of the Board of Directors to that effect or in the internal regulations of the Management Committee.

 

11. ARTICLE 11.-

 

11.1 The day-to-day management of the business of the Company and the power to represent the Company with respect thereto may be delegated by decision of the Management Committee, if any has been established, or otherwise by decision of the Board of Directors, to one or more Directors, members of the Management Committee, officers, employees or third parties (each a “Daily Manager”), acting either alone or jointly, as determined in the relevant internal regulation. A majority of the Daily Managers shall be resident in Luxembourg. The Board of Directors or the Management Committee, if any, shall approve, by a simple majority vote of the Directors or the Managing Officers, respectively, present at such meeting the internal regulations of the Daily Managers and set forth their duties.

 

11.2 The Board of Directors, the Management Committee, if any, and/or the Daily Manager(s), if any, may delegate any of their powers for specific tasks to one or more ad hoc agents, Directors, Managing Officers, Daily Managers, employee or third party and may remove any such agent(s) and will determine any such agent’s powers and responsibilities and remuneration (if any), and any other relevant conditions of such agent’s agency.

 8

 

TITLE IV - SUPERVISION

 

12. ARTICLE 12.-

 

12.1 The Company is supervised by one or more independent auditors (réviseur(s) d’entreprises agréé(s)) (the “Statutory Auditors”), which are appointed by a General Meeting.

 

12.2 Their term of office must not exceed one (1) year, however, Statutory Auditors may be re-elected. In the event that an Independent Auditor is appointed without any indication of the term of his appointment, his term is deemed to be one (1) year.

 

12.3 A Statutory Auditor may only be removed by a General Meeting for cause in accordance with Luxembourg Law or with the Statutory Auditors’ approval.

 

TITLE V. - GENERAL MEETING

 

13. ARTICLE 13.-

 

13.1 The annual General Meeting shall be held in Luxembourg at the address of the registered office of the Company or at such other place as may be specified in the convening notice of the meeting within six (6) months after the end of the accounting year as set out in Article 14.

 

13.2 Other meetings of the shareholders of the Company may be held at such place and time as may be specified in the respective convening notices of the meeting.

 

13.3 Any shareholder may participate in a General Meeting by conference call, video conference or similar means of communications equipment whereby (i) the shareholders attending the meeting can be identified, (ii) all persons participating in the meeting can hear and speak to each other, (iii) the transmission of the meeting is performed on an on-going basis, and (iv) the shareholders can properly deliberate, and participating in a meeting by such means shall constitute presence in person at such meeting.

 

13.4 Except as otherwise required by Luxembourg Law, by the rules of the New York Stock Exchange, Toronto Stock Exchange, or any stock exchange on which any Shares of the Company are then listed and any additional requirements under the rules and regulations of the U.S. Securities and Exchange Commission, Canadian securities laws and other applicable law or by these Articles, General Meetings shall be convened by the Board of Directors with at least a thirty (30) days prior notice. The quorum provided for by Luxembourg Law shall govern the notice for, and the conduct of, the General Meetings.

 

13.5 The convening notices shall be sent by registered letter or, alternatively, in any manner as set forth in applicable law or in these Articles.

 

13.6 The convening notice may be sent to a shareholder by any other means of communication having been accepted by such shareholder. Alternative means of communication are email, fax, ordinary letter and courier services.

 9

 

13.7 Only the contact details on record with the Company at least five (5) days before the issue by the Board of Directors of any notice to such shareholder shall be valid and binding on the Company. The Board of Directors shall at the registered office keep a list of the email addresses communicated by the shareholders to the Company and no third party other than the notary recording shareholder decisions shall have access to such a list.

 

13.8 Any shareholder may change its street address or email address or revoke its consent or deemed consent to alternative means of convening provided that its revocation or its new contact details are received by the Company no later than five (5) days before the issue of any notice. The Board of Directors is authorised to ask for confirmation of such new contact details by sending a registered letter or an email, as appropriate, to this new street address or email address. If the shareholder fails to confirm its new contact details, the Board of Directors shall be authorised to send any subsequent notice to the previous contact details.

 

13.9 The Board of Directors as well as the Statutory Auditors may convene a General Meeting. They shall be obliged to convene it so that it is held within a period of one month, if shareholders representing one tenth (1/10th) of the Company’s share capital require it in writing, with an indication of the agenda. One or more shareholders representing at least one tenth (1/10th) of the subscribed capital may require the entry of one or more items on the agenda of any General Meeting. This request must be addressed to the Company at least ten (10) days prior to the relevant General Meeting.

 

13.10 The Board of Directors may fix in advance a date preceding the date of (i) any General Meeting and/or (ii) for the payment of any dividend (including, without limitation, an interim dividend) as a record date for the determination of the shareholders entitled to vote at such General Meeting and/or receive payment of any such dividend, respectively, notwithstanding any transfer of any Shares on the register of the Company after any such record date.

 

Notwithstanding the provisions of the foregoing paragraph of this Article 13.10, the fixing of a record date shall be in conformity with Luxembourg Law and the rules of the New York Stock Exchange, Toronto Stock Exchange, or any stock exchange on which any Shares of the Company are then listed.

 

13.11 Each share is entitled to one vote.

 

13.12 Any shareholder may in abidance with statutory rules vote in person or through a proxy. A shareholder may act at any General Meeting by appointing any other natural or legal person who need not be a shareholder as its proxy in writing whether in original, by telefax, or e-mail to which an electronic signature (which is valid under Luxembourg Law) is affixed. Such proxy shall enjoy the same rights to speak and ask questions during the General Meeting as those to which the shareholder thus represented would be entitled. All the proxies must be received by the Company no later than the day preceding the fifth (5th) Business Day before the General Meeting unless the Board of Directors fixes a shorter period. A person acting as proxy may represent more than one shareholder.

 

13.13 Except as otherwise required by Luxembourg Law, the rules of the New York Stock Exchange, Toronto Stock Exchange, or any stock exchange on which any Shares of the Company are then listed and any additional requirements under the rules and regulations of the U.S. Securities and Exchange Commission, Canadian securities laws and other applicable law or by these Articles, resolutions at a duly convened General Meeting will be adopted by a simple majority of those present or represented and voting.

 10

 

13.14 If all the shareholders of the Company are present or represented at a General Meeting, and consider themselves as being duly convened and informed of the agenda of the meeting, the meeting may be held without prior notice.

 

13.15 The minutes of the General Meeting will be signed by the members of the bureau of the General Meeting and by any shareholder who wishes to do so.

 

13.16 However, in case decisions of the General Meeting have to be certified, copies or extracts for use in court or elsewhere must be signed by the Chairman of the Board of Directors or by the secretary of the meeting.

 

13.17 Each shareholder may vote through voting forms in the manner set out in the convening notice in relation to a General Meeting. The shareholders may only use voting forms provided by the Company and which contain at least the place, date and time of the meeting, the agenda of the meeting, the proposal submitted to the decision of the meeting, as well as for each proposal three boxes allowing the shareholder to vote in favour, against, or abstain from voting on each proposed resolution by ticking the appropriate box. Voting forms which show neither a vote in favor, nor against the resolution, nor an abstention, shall be void. The Company will only take into account voting forms received three (3) days prior to the General Meeting to which they relate and which comply with the requirements set out on the convening notice.

 

13.18 Without prejudice to any legal requirements in relation to such matters being approved by a meeting of the Board of Directors and without prejudice of any other matters that must be approved by the General Meeting according to Luxembourg Law, the General Meeting is in particular (but not limited to) vested with the rights and powers in relation to the matters set out in Articles 13.18.1 and 13.18.2.

 

13.18.1 Decisions by the General Meeting with regard to the following matters shall be adopted by a simple majority of the votes validly cast, regardless of the portion of the capital represented:

 

(a) approval of the annual accounts and respective inventory and balance sheet of the Company;

 

(b) distribution of dividends;

 

(c) appointment and removal of Directors, as provided in Article 6 above;

 

(d) appointment and removal of Statutory Auditor(s), as the case may be, as provided in Article 12 above; and

 

(e) the appointment and dismissal of liquidators and judgment of their accounts.

 11

 

13.18.2 Decisions by the General Meeting with regard to the following matters shall be adopted with a majority of two-thirds of the votes validly cast at a meeting in which holders of at least half of the Company’s issued share capital are present or represented:

 

(a) amendments to the Articles;

 

(b) transfer of the registered office of the Company outside the Grand Duchy of Luxembourg;

 

(c) capital increases other than under the Authorised Capital and capital decreases; and

 

(d) the dissolution of the Company.

 

13.18.3 If the quorum requirement set out in the preceding paragraph is not satisfied, a second meeting may be convened, in the manner prescribed by these Articles or by the Commercial Companies Law. The second convening notice shall reproduce the agenda and indicate the date and the results of the previous notice.

 

13.19 Bondholders cannot attend a General Meeting. This does not preclude shareholders who are also bondholders to attend a General Meeting in their quality as shareholders of the Company.

 

TITLE VI - ACCOUNTING YEAR, ALLOCATION OF PROFITS

 

14. ARTICLE 14.-

 

The accounting year of the Company shall begin on the 1st of January and shall terminate on the 31st of December of each year.

 

15. ARTICLE 15.-

 

15.1 Each year on the 31st of December, the accounts are closed and the Board of Directors prepares an inventory including an indication of the value of the Company’s assets and liabilities. Each shareholder may inspect the above inventory and balance sheet at the Company’s registered office.

 

15.2 From the annual net profits of the Company, five per cent (5%) shall be allocated to the legal reserve. This allocation shall cease to be mandatory as soon and as long as such reserve amounts to ten per cent (10%) of the subscribed capital of the Company, as stated in Article 5 hereof or as increased or reduced from time to time as provided in Article 5 hereof.

 

15.3 The balance is at the disposal of the General Meeting.

 

15.4 Under the terms and conditions provided by the Luxembourg Law, the Board of Directors may proceed to the payment of interim dividends to the shareholder(s) which shall be paid at the places and on the dates decided by the Board of Directors with respect to Article 13.10.

 12

 

15.5 The share premium, if any, may be freely distributed to the shareholder(s) according to Luxembourg Law by a resolution of the Board of Directors.

 

TITLE VII - DISSOLUTION, LIQUIDATION

 

16. ARTICLE 16.-

 

The Company may be dissolved by a resolution of the General Meeting. If the Company is dissolved, the liquidation will be carried out by one or more liquidators, physical or legal persons, appointed by the General Meeting, which will specify their powers and fix their remuneration.

 

TITLE VIII.- GENERAL PROVISIONS

 

17. ARTICLE 17.-

 

17.1 In these Articles:

 

17.1.1 a reference to:

 

(a) one gender shall include each gender;

 

(b) (unless the context otherwise requires) the singular shall include the plural and vice versa;

 

(c) a “person” includes a reference to any individual, firm, company, corporation or other body corporate, government, state or agency of a state or any joint venture, association or partnership, works council or employee representative body (whether or not having a separate legal personality);

 

(d) a statutory provision or statute includes all modifications thereto and all re-enactments (with or without modifications) thereof;

 

(e) a “Business Day” shall mean any day (other than a Saturday or a Sunday) on which banks in the Grand Duchy of Luxembourg are open for the conduct of non-automated banking operations.

 

17.1.2 the words “include” and “including” shall be deemed to be followed by the words “without limitation” and general words shall not be given a restrictive meaning by reason of their being preceded or followed by words indicating a particular class of acts, matters or things or by examples falling within the general words;

 

17.1.3 the headings to these Articles do not affect their interpretation or construction.

 

17.2 All matters not governed by these Articles are to be construed in accordance with the Commercial Companies Law, as amended.

 13

 

Exhibit 2.1

 

 

 

NEXA RESOURCES S.A.
as Issuer,

 

NEXA RESOURCES CAJAMARQUILLA S.A.

NEXA RESOURCES PERU S.A.A.

and

NEXA RECURSOS MINERAIS S.A.
as Guarantors,

 

and

 

THE BANK OF NEW YORK MELLON
as Trustee, Principal Paying Agent, Transfer Agent and Registrar,

 

Indenture

 

Dated as of June 18, 2020

 

 

 

U.S.$500,000,000

 

6.500% Notes due 2028

 

 

 

 

 

 

Table of Contents

 

Page

Article I

 
DEFINITIONS AND OTHER PROVISIONS OF GENERAL APPLICATION

Section 1.1. Definitions 2
Section 1.2. Compliance Certificates and Opinions 15
Section 1.3. Form of Documents Delivered to Trustee 15
Section 1.4. Acts of Holders; Record Date 16
Section 1.5. Notices, Etc., to Trustee, the Paying Agents and the Issuer 18
Section 1.6. Notice to Holders; Waiver 19
Section 1.7. Effect of Headings and Table of Contents 19
Section 1.8. Successors and Assigns 19
Section 1.9. Separability Clause 19
Section 1.10. Benefits of Indenture 19
Section 1.11. Governing Law 20
Section 1.12. Legal Holidays 20
Section 1.13. Consent to Jurisdiction and Service of Process 20
Section 1.14. Currency of Account; Conversion of Currency; Foreign Exchange Restrictions 22
Section 1.15. Counterparts 24
Section 1.16. Force Majeure 24
Section 1.17. U.S.A. PATRIOT Act 24
Section 1.18. Anti-Money Laundering, Terrorism and Economic Sanctions 24
Section 1.19. Effective Date 25

Article II

 

NOTE FORMS

Section 2.1. Forms Generally 25
Section 2.2. Form of Face of Note 26
Section 2.3. Form of Reverse of Note 29
Section 2.4. Form of Trustee’s Certificate of Authentication 34

Article III

 

THE NOTES

Section 3.1. Title and Terms 35
Section 3.2. Denominations 35
Section 3.3. Execution, Authentication, Delivery and Dating 35
Section 3.4. Global Notes; Registration, Registration of Transfer and Exchange 36

 

i 

 

 

Section 3.5. Mutilated, Destroyed, Lost and Stolen Notes 40
Section 3.6. Payment of Interest; Interest Rights Preserved 41
Section 3.7. Persons Deemed Owners 42
Section 3.8. Cancellation 42
Section 3.9. Computation of Interest 43
Section 3.10. CUSIP Numbers 43
Section 3.11. Paying Agents; Discharge of Payment Obligations; Indemnity of Holders 43

Article IV

 

REDEMPTION OF NOTES

Section 4.1. Redemption for Tax Reasons 44
Section 4.2. Optional Redemption 45
Section 4.3. Applicability of Article 46
Section 4.4. Election to Redeem; Notice to Trustee, Registrar and Paying Agent 46
Section 4.5. Notice of Redemption 46
Section 4.6. Deposit of Redemption Price 47
Section 4.7. Notes Payable on Redemption Date 47

Article V

 

SATISFACTION AND DISCHARGE

Section 5.1. Satisfaction and Discharge of Indenture 47
Section 5.2. Application of Trust Money 48

Article VI

 

REMEDIES

Section 6.1. Events of Default 49
Section 6.2. Collection of Indebtedness and Suits for Enforcement by Trustee 50
Section 6.3. Trustee May File Proofs of Claim 51
Section 6.4. Trustee May Enforce Claims Without Possession of Notes 51
Section 6.5. Application of Money Collected 52
Section 6.6. Limitation on Suits 52
Section 6.7. Unconditional Right of Holders to Receive Principal, Premium and Interest 53
Section 6.8. Restoration of Rights and Remedies 53
Section 6.9. Rights and Remedies Cumulative 53
Section 6.10. Delay or Omission Not Waiver 53
Section 6.11. Control by Holders 54
Section 6.12. Waiver of Past Defaults 54
Section 6.13. Undertaking for Costs 54

 

ii 

 

 

Article VII

 
THE TRUSTEE

Section 7.1. Certain Duties and Responsibilities 55
Section 7.2. Notice of Defaults 57
Section 7.3. Certain Rights of Trustee and the Agents 57
Section 7.4. Not Responsible for Recitals or Issuance of Notes 59
Section 7.5. May Hold Notes 59
Section 7.6. Money Held in Trust 59
Section 7.7. Compensation and Reimbursement 59
Section 7.8. Corporate Trustee Required; Eligibility 60
Section 7.9. Resignation and Removal; Appointment of Successor 60
Section 7.10. Acceptance of Appointment by Successor 62
Section 7.11. Merger, Conversion, Consolidation or Succession to Business 62
Section 7.12. Appointment of Authenticating Agent 62

Article VIII

 

HOLDERS LISTS AND COMMUNICATIONS BY TRUSTEE AND ISSUER

Section 8.1. Issuer to Furnish Trustee; Names and Addresses of Holders 64
Section 8.2. Preservation of Information; Communications to Holders 64

Article IX

 

CONSOLIDATION, MERGER, CONVEYANCE, TRANSFER OR LEASE

Section 9.1. Mergers, Consolidations and Certain Sales of Assets 65

Article X

 

SUPPLEMENTAL INDENTURES

Section 10.1. Supplemental Indentures Without Consent of Holders 66
Section 10.2. Supplemental Indentures with Consent of Holders 67
Section 10.3. Execution of Supplemental Indentures 68
Section 10.4. Effect of Supplemental Indentures 68
Section 10.5. Reference in Notes to Supplemental Indentures 68
Section 10.6. Notice to Holders 68

Article XI

 

COVENANTS

Section 11.1. Payment Under the Notes 69
Section 11.2. Maintenance of Office or Agency 69
Section 11.3. Money for Note Payments to Be Held in Trust 69

 

iii 

 

 

Section 11.4. Maintenance of Corporate Existence 71
Section 11.5. Repurchases at the Option of the Holders upon Change of Control 71
Section 11.6. Payment of Taxes and Other Claims 73
Section 11.7. Provision of Financial Information 73
Section 11.8. Statement by Officers as to Default 73
Section 11.9. Payment of Additional Amounts 74
Section 11.10. Limitation on Liens 76
Section 11.11. [Intentionally Omitted] 78
Section 11.12. Performance Obligations Under Other Documents 78
Section 11.13. Compliance with Laws 78
Section 11.14. Maintenance of Government Approvals 78
Section 11.15. [Intentionally Omitted] 78
Section 11.16. Maintenance of Books and Records 78
Section 11.17. Ranking 79

Article XII

 

LEGAL DEFEASANCE AND COVENANT DEFEASANCE

Section 12.1. Option to Effect Defeasance or Covenant Defeasance 79
Section 12.2. Defeasance and Discharge 79
Section 12.3. Covenant Defeasance 79
Section 12.4. Conditions to Defeasance or Covenant Defeasance 80
Section 12.5. Deposited Money and U.S. Government Obligations to Be Held in Trust; Other Miscellaneous Provisions 81
Section 12.6. Reinstatement 82
Section 12.7. Repayment to Issuer or the Guarantors 82

Article XIII

 

SUBSTITUTION OF THE ISSUER

Section 13.1. Substitution of the Issuer 83

Article XIV

 

GUARANTEES

Section 14.1. Guarantees 85
Section 14.2. Delivery of the Guarantee 87
Section 14.3. Release of Guarantor 87

Article XV

 

MEETINGS OF HOLDERS OF SECURITIES

Section 15.1. Purposes for Which Meetings May Be Called 87
Section 15.2. Call, Notice and Place of Meetings 87

 

iv 

 

 

Section 15.3. Persons Entitled to Vote at Meetings 88
Section 15.4. Quorum; Action 88
Section 15.5. Determination of Voting Rights; Conduct and Adjournment of Meetings 89
Section 15.6. Counting Votes and Recording Action of Meetings 90

 

EXHIBITS

 

Exhibit A FORM OF CERTIFICATION FOR TRANSFER OR EXCHANGE OF RESTRICTED GLOBAL SECURITY TO REGULATION S GLOBAL SECURITY
     
Exhibit B FORM OF CERTIFICATION FOR TRANSFER OR EXCHANGE OF REGULATION S GLOBAL SECURITY TO RESTRICTED GLOBAL SECURITY
     
Exhibit C-1 FORM OF CERTIFICATION FOR TRANSFER OR EXCHANGE OF NON-GLOBAL RESTRICTED SECURITY TO RESTRICTED GLOBAL SECURITY
     
Exhibit C-2 FORM OF CERTIFICATION FOR TRANSFER OR EXCHANGE OF NON-GLOBAL RESTRICTED SECURITY TO REGULATION S GLOBAL SECURITY
     
Exhibit D-1 FORM OF CERTIFICATION FOR TRANSFER OR EXCHANGE OF NON-GLOBAL REGULATION S SECURITY TO RESTRICTED GLOBAL SECURITY
     
Exhibit D-2 FORM OF CERTIFICATION FOR TRANSFER OR EXCHANGE OF NON-GLOBAL REGULATION S SECURITY TO REGULATION S GLOBAL SECURITY

 

Note:    This Table of Contents shall not, for any purpose, be deemed to be part of this Indenture.

 

v 

 

 

 

THIS INDENTURE, dated as of June 18, 2020, among Nexa Resources S.A., a public limited liability company validly organized under the laws of the Grand Duchy of Luxembourg having its registered office at 37A Avenue J.F. Kennedy, L-1855, Luxembourg, Grand Duchy of Luxembourg and registered with the Registre de Commerce et des Sociétés in Luxembourg under number B 185.489 (the “Issuer”), Nexa Resources Cajamarquilla S.A., a corporation (sociedad anónima) validly organized under the laws of the Republic of Peru (“Nexa CJM”), Nexa Resources Perú S.A.A., a publicly held corporation (sociedad anónima abierta) validly organized under the laws of the Republic of Peru (“Nexa Peru”), Nexa Recursos Minerais S.A., a corporation (sociedade anônima) validly organized under the laws of the Federative Republic of Brazil (“Nexa Brazil”, and, together with Nexa CJM and Nexa Peru, the “Guarantors”), and The Bank of New York Mellon, a New York banking corporation, as trustee (the “Trustee”), a paying agent (the “Principal Paying Agent” and any other paying agents to be appointed hereunder, the “Paying Agents”), transfer agent (the “Transfer Agent”), and registrar (the “Registrar”) and any other paying agents to be appointed hereunder, the “Paying Agents”.

 

RECITALS

 

WHEREAS, the Issuer has duly authorized the creation of an issue of U.S.$500,000,000 of its 6.500% Notes due 2028 (the “Initial Notes” and, together with any Additional Notes (as defined herein) issued as provided for in Section 2.2 and 2.17 hereof, the “Notes”) of substantially the tenor and amount hereinafter set forth, and to provide therefor the Issuer has duly authorized the execution and delivery of this Indenture.

 

WHEREAS, Nexa CJM, Nexa Peru and Nexa Brazil have duly authorized the execution and delivery of this Indenture to provide for their Guarantees with respect to the Notes as set forth in this Indenture.

 

WHEREAS, all things necessary (i) to make the Initial Notes, when executed by the Issuer and authenticated and delivered hereunder and duly issued by the Issuer, the valid obligations of the Issuer, (ii) to make the Guarantees of Nexa CJM, Nexa Peru and Nexa Brazil, when executed by Nexa CJM, Nexa Peru and Nexa Brazil and endorsed on the Notes executed, authenticated and delivered hereunder, the valid obligations of Nexa CJM, Nexa Peru and Nexa Brazil and (iii) to make this Indenture a valid agreement of the Issuer, Nexa CJM, Nexa Peru and Nexa Brazil, all, in accordance with their respective terms, have been done.

 

NOW, THEREFORE, THIS INDENTURE WITNESSETH:

 

For and in consideration of the premises and the purchase of the Notes by the Holders (as defined below) thereof, it is mutually covenanted and agreed, for the equal and proportionate benefit of all Holders of the Notes, as follows:

 

 

 

 

Article I

 

DEFINITIONS AND OTHER PROVISIONS
OF GENERAL APPLICATION

 

Section 1.1.          Definitions.

 

For all purposes of this Indenture, except as otherwise expressly provided or unless the context otherwise requires:

 

(1)          the terms defined in this Article have the meanings assigned to them in this Article and include the plural as well as the singular;

 

(2)          all accounting terms not otherwise defined herein have the meanings assigned to them in accordance with GAAP (whether or not such is indicated herein);

 

(3)          the words “herein,” “hereof” and “hereunder” and other words of similar import refer to this Indenture as a whole and not to any particular Article, Section or other subdivision;

 

(4)          whenever there is mentioned in this Indenture, in any context, the payment of, or in respect of, a Redemption Price, the principal of or any premium or interest on any Note or the net proceeds received on the sale or exchange of any Notes, such mention shall be deemed to include mention of the payment of Additional Amounts to the extent that, in such context, Additional Amounts are, were or would be payable in respect thereof pursuant to this Indenture;

 

(5)          All references in this Indenture to “$,” “U.S.$,” “dollars” or “United States dollars” shall refer to the lawful currency of the United States.

 

Act” when used with respect to any Holder, has the meaning specified in Section 1.4. “Additional Amounts” has the meaning specified in Section 11.9.

 

Additional Notes” means additional 6.500% Notes due 2028 issued from time to time after the Issue Date under the terms of this Indenture.

 

Affiliate” of any Person means any other Person controlling or controlled by or under direct or indirect common control with such Person. For the purposes of this definition, “control,” when used with respect to any Person, means the power to direct the management and policies of such Person, directly or indirectly, whether through the ownership of voting securities, by contract or otherwise; and the terms “controlling” and “controlled” have meanings correlative to the foregoing.

 

Agent Member” means any member of, or participant in, the Depositary.

 

Agents” means any Paying Agent, the Registrar, the Transfer Agent and any Principal Paying Agent appointed hereunder.

 

2

 

 

Bankruptcy Law” means Title 11, United States Code, Brazilian Federal Law No. 11,101, dated February 9, 2005, as amended, or any similar federal or state law relating to bankruptcy, insolvency, receivership, winding-up, suspension of payments, liquidation, reorganization or relief of debtors or the law of any other jurisdiction relating to bankruptcy, insolvency, receivership, winding-up, suspension of payments, liquidation, dissolution, “procedimiento concursal ordinario,” “procedimiento concursal preventivo,” “procedimiento acelerado de refinanciación concursal,” “recuperação judicial,” “recuperação extrajudicial,” reorganization or relief of debtors, the judicial proceedings referred to in article 13, items 2 to 11 of the Luxembourg law dated 19 December 2002 relating to the register of commerce and companies as well as the accounting and the annual accounts of companies, as amended, including in particular, bankruptcy (faillite), controlled management (gestion contrôlée), suspension of payments (sursis de paiement), arrangement with creditors (concordat préventif de la faillite) and judicial liquidation (liquidation judiciaire) proceedings or any amendment to, succession to or change in any such law, procedure or process.

 

Bankruptcy Order” means any court order made in a proceeding pursuant to or within the meaning of any Bankruptcy Law, containing an adjudication of bankruptcy or insolvency, or providing for liquidation, receivership, winding-up, dissolution, “procedimiento concursal ordinario,” “procedimiento concursal preventivo,” “procedimiento acelerado de refinanciación concursal,” “recuperação judicial,” “recuperação extrajudicial,” or reorganization, or appointing a custodian of a debtor or of all or any substantial part of a debtor’s property, or providing for the staying, arrangement, adjustment or composition of Indebtedness or other relief of a debtor or in any court order made in connection with the judicial proceedings referred to in article 13, items 2 to 11 of the Luxembourg law dated 19 December 2002 relating to the register of commerce and companies as well as the accounting and the annual accounts of companies, as amended, including in particular, bankruptcy (faillite), controlled management (gestion contrôlée), suspension of payments (sursis de paiement), arrangement with creditors (concordat préventif de la faillite) and judicial liquidation (liquidation judiciaire) proceedings.

 

Base Currency” has the meaning set forth in Section 1.14.

 

Board of Directors” means the board of directors of the Issuer.

 

Board Resolution” means a duly adopted resolution of the Board of Directors in full force and effect at the time of determination.

 

Brazil” means the Federative Republic of Brazil and any ministry, department, authority (including the Central Bank of Brazil) or statutory corporation or other entity (including a trust), owned or controlled directly or indirectly by the Federative Republic of Brazil or any of the foregoing.

 

Business Day” means each day that is not a Saturday, Sunday or other day on which banking institutions in New York, United States, Luxembourg, Grand Duchy of Luxembourg, São Paulo, Brazil or Lima, Peru are authorized or required by law to close.

 

3

 

 

Capital Lease Obligation” of any Person means the obligation to pay rent or other payment amounts under a lease of (or other Indebtedness arrangements conveying the right to use) real or personal property of such Person which is required to be classified and accounted for as a capital lease or a liability set forth on a balance sheet of such Person in accordance with applicable GAAP. The stated maturity of such obligation shall be the date of the last payment of rent or any other amount due under such lease prior to the first date upon which such lease may be terminated by the lessee without payment of a penalty. The principal amount of such obligation shall be the capitalized amount thereof that would appear on the face of a balance sheet of such Person in accordance with applicable GAAP.

 

Capital Stock” of any Person means any and all shares, interests, participations or other equivalents (however designated and whether voting or non-voting) of corporate stock or other equity participations or ownership interests, including quotas in a Brazilian limited liability quota company (limitada) or partnership interests, whether general or limited, of such Person.

 

Cash Equivalents” means:

 

(1)          United States dollars, Brazilian reais, Peruvian soles, euros, or money in other currencies received in the ordinary course of business of the Issuer and its Subsidiaries that are readily convertible into United States dollars or euros,

 

(2)          any evidence of Debt with a maturity of 180 days or less issued or directly and fully guaranteed or insured by Brazil, Peru or the United States or any agency or instrumentality thereof, provided that the full faith and credit of Brazil, Peru or the United States is pledged in support thereof,

 

(3)          (i) demand deposits, (ii) time deposits and certificates of deposit with maturities of one year or less from the date of acquisition, (iii) bankers’ acceptances with maturities not exceeding one year from the date of acquisition, and (iv) overnight bank deposits, in each case with any bank or trust company organized or licensed under the laws of Luxembourg, Brazil, Peru or the United States or any political subdivision or state thereof having capital, surplus and undivided profits in excess of U.S.$500.0 million whose short-term debt is rated “A-2” or higher by S&P or “P-2” or higher by Moody’s,

 

(4)          repurchase obligations with a term of not more than seven days for underlying securities of the type described in clauses (2) and (3) above entered into with any financial institution meeting the qualifications specified in clause (3) above,

 

(5)          commercial paper rated at least P-1 by Moody’s or A-1 by S&P and maturing within six months after the date of acquisition, and

 

(6)          money market funds at least 95% of the assets of which consist of investments of the type described in clauses (1) through (5) above.

 

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Change of Control” means that the Permitted Holders shall cease to own, directly or indirectly, at least a majority of the outstanding voting power of the Voting Stock of the Issuer and shall cease to have the power to direct or cause the direction of the management and policies of the Issuer.

 

Change of Control Offer” has the meaning specified in Section 11.5.

 

Change of Control Payment” has the meaning specified in Section 11.5.

 

Change of Control Payment Date” has the meaning specified in Section 11.5.

 

Central Bank” means (i) the Central Bank of Luxembourg, (ii) the Central Bank of Brazil and (iii) the Central Reserve Bank of Peru or, in each case, any successor entity thereto.

 

Change of Law” has the meaning specified in Section 3.1.

 

Clearstream” means Clearstream Banking, société anonyme.

 

Code” means the United States Internal Revenue Code of 1986, as amended.

 

Comparable Treasury Issue” means the United States Treasury security or securities selected by an Independent Investment Banker as having an actual or interpolated maturity comparable to the period from the Redemption Date to the Par Call Date that would be utilized, at the time of selection and in accordance with customary financial practice, in pricing new issues of corporate debt securities of a comparable maturity to the period from the Redemption Date to the Par Call Date.

 

Comparable Treasury Price” means, with respect to any Redemption Date, (1) the average of the Reference Treasury Dealer Quotations for such redemption date, after excluding the highest and lowest such Reference Treasury Dealer Quotation, or (2) if the Issuer or a Guarantor obtains fewer than four such Reference Treasury Dealer Quotations, the average of all such quotations.

 

Consolidated Total Assets” means, on a consolidated basis, the Issuer’s total amount of assets, calculated based on the most recent balance sheet delivered by the Issuer to the Trustee pursuant to this Indenture, after giving pro forma effect to any acquisition or disposition of companies, divisions, lines of businesses, operations or assets by the Issuer and its Subsidiaries subsequent to such date.

 

Corporate Trust Office” means the principal office of the Trustee in The City of New York, New York, at which at any particular time its corporate trust business shall be administered, which at the date hereof is located at 240 Greenwich Street, New York, New York 10286, United States, Attention: Global Corporate Trust, Fax: (212) 815-5603, and such other offices as the Trustee may designate from time to time.

 

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corporation” means a corporation, association, company, limited liability company, joint stock company or business trust.

 

covenant defeasance” has the meaning specified in Section 12.3.

 

Default” means an event that with the passing of time or the giving of notice or both shall constitute an Event of Default.

 

Defaulted Interest” has the meaning specified in Section 3.6.

 

Depositary” means, with respect to the Notes issuable or issued in whole or in part in the form of one or more Global Notes, DTC for so long as it shall be a clearing agency registered under the Exchange Act, or such successor as the Issuer shall designate from time to time in an Officer’s Certificate delivered to the Trustee.

 

Designated Subsidiary” means (i) each Guarantor and (ii) any other Subsidiary of the Issuer which, as of the date of the Issuer’s most recent quarterly or annual, as applicable, consolidated balance sheet, constituted 15% or more of the Consolidated Total Assets of the Issuer, after giving pro forma effect to any acquisition or disposition of companies, divisions, lines of businesses, operations or assets by the Issuer and its Subsidiaries subsequent to such date.

 

Director” means a member of the Board of Directors.

 

Disqualified Stock” of any Person means any Capital Stock of such Person which, by its terms (or by the terms of any security into which it is convertible or for which it is exchangeable), or upon the happening of any event, matures or is mandatorily redeemable, pursuant to a sinking fund obligation or otherwise, or is redeemable at the option of the holder thereof, in whole or in part, on or prior to the Stated Maturity of the Notes.

 

DTC” means The Depository Trust Company.

 

Euroclear” means Euroclear Bank S.A./N.V., as operator of the Euroclear system or its successors.

 

Event of Default” has the meaning specified in Section 6.1.

 

Exchange Act” means the United States Securities Exchange Act of 1934, as amended (or any successor act), and the rules and regulations thereunder.

 

Expiration Date” has the meaning set forth in Section 1.4.

 

FATCA” means Sections 1471 to 1474 of the U.S. Internal Revenue Code of 1986, as amended.

 

Fitch” means Fitch Rating Service, Inc. and its successors.

 

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GAAP” means, as elected from time to time by the Issuer, (i) generally accepted accounting principles prescribed by the laws, rules and regulations applicable in the jurisdiction of incorporation of the Issuer, (ii) International Financial Reporting Standards, or (iii) accounting practices generally accepted in the United States, in each case, as in effect from time to time.

 

Global Note” means, as the context may require, any or all of the Regulation S Global Note(s) and the Restricted Global Note(s), evidencing all or part of a series of Notes which is issued to the Depositary or its nominee and is registered in the name of the Depositary or its nominee.

 

guarantee” by any Person means any obligation, contingent or otherwise, of such Person guaranteeing, or having the economic effect of guaranteeing, any Indebtedness of any other Person (the “primary obligor”) in any manner, whether directly or indirectly, and including, without limitation, any obligation of such Person, (i) to purchase or pay (or advance or supply funds for the purchase or payment of) such Indebtedness or to purchase (or to advance or supply funds for the purchase of) any security for the payment of such Indebtedness, (ii) to purchase property, securities or services for the purpose of assuring the holder of such Indebtedness of the payment of such Indebtedness, or (iii) to maintain working capital, equity capital or other financial statement condition or liquidity of the primary obligor so as to enable the primary obligor to pay such Indebtedness (and “guaranteed,” “guaranteeing” and “guarantor” shall have meanings correlative to the foregoing); provided that, the guarantee by any Person shall not include endorsements by such Person for collection or deposit, in either case, in the ordinary course of business; provided further that, the Incurrence by the Issuer or a Designated Subsidiary of a Lien permitted under clause (2) of Section 11.10 shall not be deemed to constitute a guarantee by the Issuer or a Designated Subsidiary of any purchase money debt of such Person secured thereby.

 

Guarantee” means the guarantee by the Guarantors of the due and punctual payment of the principal (and premium, if any) and interest (including any Additional Amounts) on, the Notes and other amounts due under this Indenture.

 

Guarantors” mean Nexa CJM, Nexa Peru and Nexa Brazil.

 

Holder” means a Person in whose name a Note is registered on the Registrar’s books.

 

Incur” means, with respect to any Indebtedness or other obligation of any Person, to create, issue, incur (by conversion, exchange or otherwise), assume, guarantee or otherwise become liable in respect of such Indebtedness or other obligation including by acquisition of Subsidiaries or the recording, as required pursuant to applicable GAAP or otherwise, of any such Indebtedness or other obligation on the balance sheet of such Person (and “Incurrence,” “Incurred,” “Incurrable” and “Incurring” shall have meanings correlative to the foregoing); provided that a change in applicable GAAP that results in an obligation of such Person that exists at such time becoming Indebtedness shall not be deemed an Incurrence of such Indebtedness and that neither the accrual of interest nor the accretion of original issue discount shall be deemed an Incurrence of Indebtedness; provided further that, the Issuer may elect to treat all or any portion of revolving credit debt commitments, whether or not then outstanding, of the Issuer or a Subsidiary as being incurred from and after any date beginning the date the relevant revolving credit commitment is extended to the Issuer or a Subsidiary, as the case may be, by furnishing written notice thereof to the Trustee, and any borrowings or reborrowings by the Issuer or a Subsidiary under such commitment up to the amount of such commitment designated by the Issuer or such Subsidiary as Incurred shall not be deemed to be new Incurrences of Indebtedness by the Issuer or such Subsidiary, as the case may be.

 

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Indebtedness” means (without duplication), with respect to any Person, whether recourse is to all or a portion of the assets of such Person and whether or not contingent, (i) every obligation of such Person for money borrowed, (ii) every obligation of such Person evidenced by bonds, debentures, notes or other similar instruments, including any such obligations Incurred in connection with the acquisition of property, assets or businesses, (iii) every reimbursement obligation of such Person with respect to letters of credit, bankers’ acceptances or similar facilities issued for the account of such Person, (iv) every obligation of such Person issued or assumed as the deferred purchase price of property or services (including securities repurchase agreements but excluding trade accounts payable or accrued liabilities arising in the ordinary course of business which are payable on customary trade terms or which are being contested in good faith), (v) all obligations to redeem Disqualified Stock issued by such Person, (vi) every Net Obligation under Interest Rate or Currency Protection Agreements of such Person, (vii) every Capital Lease Obligation of such Person, and (viii) every obligation of the type referred to in clauses (i) through (vii) of another Person and all dividends of another Person the payment of which, in either case, such Person has guaranteed, other than with respect to clauses (iii) and (vi) above, in each case, if and to the extent any of the preceding items would appear as a liability upon the financial statements of the specified Person in accordance with applicable GAAP.

 

Indenture” means this instrument as originally executed or as it may from time to time be supplemented or amended by one or more supplemental indentures hereto entered into pursuant to the applicable provisions hereof.

 

Independent Investment Banker” means one of the Reference Treasury Dealers appointed by the Issuer or a Guarantor.

 

Initial Notes” means the U.S.$500,000,000 of Notes designated in the first paragraph of the Recitals.

 

Interest Payment Date” means each January 18 and July 18, commencing January 18, 2021.

 

Interest Rate or Currency Protection Agreement” of any Person means any forward contract, futures contract, swap, option, hedge or other financial agreement or arrangement (including, without limitation, caps, floors, collars and similar agreements) relating to, or the value of which is dependent upon, interest rates or currency exchange rates or indices.

 

Investment Grade Rating” means a rating equal to or higher than (i) BBB- (or the equivalent) by S&P, (ii) Baa3 (or the equivalent) by Moody’s or (iii) BBB- (or the equivalent) by Fitch.

 

Issuer” means the Person named as the “Issuer” in the first paragraph of this instrument until a successor Person shall have become such pursuant to the applicable provisions of this Indenture and thereafter “Issuer” shall mean such successor Person.

 

Issue Date” means June 18, 2020.

 

Issuer Request” or “Issuer Order” means a written request or order signed in the name of the Issuer by an authorized signatory of the Issuer and delivered to the Trustee.

 

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Lien” means any mortgage, pledge, security interest, encumbrance or charge of any kind (including, without limitation, any conditional sale or other title retention agreement or lease in the nature thereof or any agreement to give any security interest).

 

Luxembourg” means the Grand Duchy of Luxembourg and any ministry, department, authority (including the Central Bank of Luxembourg) or statutory corporation or other entity (including a trust), owned or controlled directly or indirectly by the Grand Duchy of Luxembourg or any of the foregoing.

 

Maturity” when used with respect to any Note, means the date on which the principal of such Note becomes due and payable as therein or herein provided, whether at the Stated Maturity or by declaration of acceleration, call for redemption or otherwise.

 

Maturity Date” means January 18, 2028.

 

Moody’s” means Moody’s Investors Service, Inc. and its successors.

 

Net Obligation” at any date of determination means the net amount, exclusive of any commissions or administrative fees that a Person would be obligated to pay upon the termination of an Interest Rate or Currency Protection Agreement as of such date.

 

Nexa Brazil” means the Person named as “Nexa Brazil” in the first paragraph of this instrument until a successor Person shall have become such pursuant to the applicable provisions of this Indenture and thereafter “Nexa Brazil” shall mean such successor Person.

 

Nexa CJM” means the Person named as “Nexa CJM” in the first paragraph of this instrument until a successor Person shall have become such pursuant to the applicable provisions of this Indenture and thereafter “Nexa CJM” shall mean such successor Person.

 

Nexa Peru” means the Person named as “Nexa Peru” in the first paragraph of this instrument until a successor Person shall have become such pursuant to the applicable provisions of this Indenture and thereafter “Nexa Peru” shall mean such successor Person.

 

Note Register” has the meaning specified in Section 3.4(b).

 

Notes” has the meaning specified in the first paragraph of the Recitals.

 

Notice of Default” has the meaning set forth in Section 7.2.

 

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OECD” means the Organization for Economic Co-operation and Development.

 

Officer’s Certificate” means a certificate signed by any of the following: the Chief Executive Officer, President, Chief Financial Officer or a Vice President; and delivered to the Trustee and containing the statements provided for in Section 1.2 hereof (if applicable).

 

Opinion of Counsel” means a written opinion of legal counsel, who may be counsel for the Issuer or a Guarantor, containing the statements provided for in Section 1.2 in form and substance reasonably acceptable to the Trustee.

 

Outstanding” when used with respect to the Notes, means, as of the date of determination, all the Notes theretofore authenticated and delivered under this Indenture (including, as of such date, all the Notes represented by Global Notes authenticated and delivered under this Indenture), except the reduced portion or portions of any Global Note, as such reduction or reductions shall have been endorsed on such Global Note by the Trustee as provided herein and, except:

 

(i)           the Notes theretofore cancelled by the Trustee or delivered to the Trustee for cancellation;

 

(ii)          the Notes for whose payment or redemption money in the necessary amount has been theretofore deposited with the Trustee or any Paying Agent (other than the Issuer) in trust or set aside and segregated in trust by the Issuer (if the Issuer shall act as its own Paying Agent) for the Holders of such Notes; provided that if such Notes are to be repurchased, notice of such repurchase has been duly given pursuant to this Indenture; and

 

(iii)         Notes which have been issued pursuant to Section 3.5 or in exchange for or in lieu of which other Notes have been authenticated and delivered pursuant to this Indenture, other than any such Notes in respect of which there shall have been presented to the Trustee proof satisfactory to it that such Notes are held by a bona fide purchaser in whose hands such Notes are valid obligations of the Issuer;

 

provided, however, that in determining whether the Holders of the requisite principal amount of the Outstanding Notes have given any request, demand, authorization, direction, notice, consent or waiver hereunder, Notes owned by the Issuer or any other obligor upon the Notes or any Affiliate of the Issuer or of such other obligor shall be disregarded and deemed not to be Outstanding, except that, in determining whether the Trustee shall be protected in relying upon any such request, demand, authorization, direction, notice, consent or waiver, only Notes which a Responsible Officer of the Trustee actually knows to be so owned shall be so disregarded. Notes so owned which have been pledged in good faith may be regarded as Outstanding if the pledgee establishes to the satisfaction of the Trustee the pledgee’s right so to act with respect to such Notes and that the pledgee is not the Issuer or any other obligor upon the Notes or any Affiliate of the Issuer or of such other obligor.

 

Paying Agent” means any Person authorized by the Issuer to pay the principal of (and premium, if any) or interest on any Notes on behalf of the Issuer. The Issuer has initially appointed the Principal Paying Agent to act as Paying Agent.

 

Payment Date” has the meaning set forth in Section 3.11(b).

 

Permitted Holders” mean (i) the estate of Mr. Antonio Ermírio de Moraes and any of Mr. Ermírio Pereira de Moraes, Mrs. Maria Helena de Moraes Scripilliti and Mr. José Ermírio de Moraes Filho and any of their descendants, (ii) any Affiliate of any of the foregoing and (iii) any corporation, partnership, joint venture, association, trust, fund, unincorporated organization, or any other entity or group formed pursuant to a shareholders, control or voting agreement or similar agreement, of which any one or more of the Permitted Holders referred to in clauses (i) or (ii) hereof is a shareholder, partner, beneficiary, member or party.

 

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Permitted Holding Company” means any entity which owns at least 95% of the outstanding Capital Stock or other ownership interests (other than directors’ qualifying shares) of the Issuer.

 

Person” means any individual, corporation, partnership, joint venture, association, trust, unincorporated organization, government or agency or political subdivision thereof or any other entity.

 

Peru” means the Republic of Peru and any ministry, department, authority (including the Central Reserve Bank of Peru) or statutory corporation or other entity (including a trust), owned or controlled directly or indirectly by the Republic of Peru or any of the foregoing.

 

Predecessor Note” of any particular Note means every previous Note evidencing all or a portion of the same debt as that evidenced by such particular Note; and, for the purposes of this definition, any Note authenticated and delivered under Section 3.5 in exchange for or in lieu of a mutilated, destroyed, lost or stolen Note shall be deemed to evidence the same debt as the mutilated, destroyed, lost or stolen Note.

 

Principal Paying Agent” means The Bank of New York Mellon, a New York banking corporation, or any successor in its capacity as Principal Paying Agent.

 

Rating Agency” means each of S&P, Moody’s and Fitch; provided that if any of S&P, Moody’s or Fitch ceases to rate the Notes or fails to make a rating on the Notes publicly available, the Issuer will appoint a replacement for such Rating Agency that is a “nationally recognized statistical rating organization” within the meaning of Rule 15c3-1(c)(2)(vi)(F) under the Exchange Act.

 

Rating Date” means the date which is 90 days prior to the earlier of (i) a Change of Control and (ii) public notice of the occurrence of a Change of Control or of the intention of the Permitted Holders or the Issuer to effect a Change of Control.

 

Rating Decline” means the occurrence of the following on, or within 90 days after, the date of public notice of the occurrence of a Change of Control or of the intention by a Permitted Holder or the Issuer to effect a Change of Control (which period shall be extended so long as the rating of the Notes is under publicly announced consideration for possible downgrade by any of the Rating Agencies): (i) in the event the Notes are assigned an Investment Grade Rating by at least two of the Rating Agencies on the Rating Date, the rating of the Notes by at least two of the Rating Agencies shall be below an Investment Grade Rating; or (ii) in the event the Notes are rated below an Investment Grade Rating by at least two of the Rating Agencies on the Rating Date, the rating of the Notes by at least two of the Rating Agencies shall be decreased by one or more gradations (including gradations (but not outlooks) within rating categories as well as between rating categories); provided that any such Rating Decline is in whole or in part in connection with a Change of Control. The Issuer will provide the Trustee with prompt written notice of any Rating Decline, and the Trustee shall not be deemed to have knowledge of any Rating Decline until it receives such notice.

 

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rate(s) of exchange” has the meaning set forth in Section 1.14.

 

Receivables” means receivables, chattel paper, instruments, documents or intangibles evidencing or relating to the right to payment of money in respect of the sale of goods or services.

 

Redemption Date” when used with respect to any Note to be redeemed, means the date fixed for such redemption by or pursuant to this Indenture.

 

Redemption Price” when used with respect to any Note to be redeemed, means the price at which it is to be redeemed pursuant to this Indenture.

 

Reference Treasury Dealer” means at least four dealers which are primary United States government securities dealers in New York City reasonably designated by the Issuer or a Guarantor.

 

Reference Treasury Dealer Quotation” means, with respect to each Reference Treasury Dealer and any Redemption Date, the average, as determined by the Issuer, of the bid and asked prices for the Comparable Treasury Issue (expressed in each case as a percentage of its principal amount) quoted in writing to the Issuer or a Guarantor by such Reference Treasury Dealer at 3:30p.m. New York time on the third business day preceding such Redemption Date.

 

Registrar” has the meaning specified in Section 3.4(b).

 

Regular Record Date” for the interest payable on any Interest Payment Date means the second day (whether or not a Business Day), as the case may be, next preceding such Interest Payment Date.

 

Responsible Officer” means any officer within the corporate trust department of the Trustee, including any director, managing director, vice president, assistant vice president, trust officer, assistant trust officer or any other officer or assistant officer of the Trustee customarily performing functions similar to those performed by the persons who at that time shall be such officers having direct responsibility for the administration of this Indenture, and also means, with respect to a particular corporate trust matter, any other officer to whom such trust matter is referred because of his or her knowledge of and familiarity with the particular subject.

 

Regulation S” means Regulation S (including any successor regulation thereto) under the Securities Act, as it may be amended from time to time.

 

Regulation S Global Note” has the meaning set forth in Section 2.1

 

Restricted Global Note” has the meaning set forth in Section 2.1.

 

Restricted Notes” means the Restricted Global Note and any Successor Note, other than (i) any Note issued upon a transfer or exchange for which a certificate substantially in the form set forth in (a) Exhibit A is required to be provided and is provided pursuant to Section 3.4(c)(2) or (b) Exhibit C-2 is required to be provided and is provided pursuant to Section 3.4(c)(5), (ii) any Note issued in exchange for or in lieu of any Note specified in clause (i) of this definition or any Note issued in exchange therefor or in lieu thereof, or (iii) any Note as to which the Issuer has removed and has not replaced the legend described in Section 3.4(b).

 

Restricted Property” means any mineral property (including any mineral concessions, authorizations or rights in respect of minerals granted by any governmental authority), concentrate plant, manufacturing or processing plant used in connection with the processing, refining or manufacturing of metals or minerals, power plant or transmission lines of the Issuer or any Designated Subsidiary and any capital stock of any Subsidiary directly owning any such mineral property, concentrate, manufacturing or processing plant, power plant or transmission lines.

 

Reuters” means Reuters Group plc, a U.K. corporation, and its successors and assigns.

 

Rule 144A” means Rule 144A (including any successor regulation thereto) under the Securities Act, as it may be amended from time to time.

 

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S&P” means S&P Global Ratings, a business unit of Standard & Poor’s Financial Services LLC and its successors.

 

SEC” means the United States Securities and Exchange Commission.

 

Securities Act” means the United States Securities Act of 1933, as amended, and the rules and regulations of the SEC promulgated thereunder.

 

Securitization Transaction” means a transaction in which the Issuer or a Subsidiary thereof sells or transfers an interest in Receivables (and/or any rights arising under the documentation governing or relating to such Receivables covered by such transaction, any proceeds of Receivables and any lockboxes or accounts in which such proceeds are deposited and any related assets) to a special purpose entity that issues securities payable from collections of such Receivables or other assets.

 

Special Record Date” for the payment of any Defaulted Interest means a date fixed by the Trustee pursuant to Section 3.6.

 

Stated Maturity” when used with respect to any Note or any installment of interest thereon, means the date specified in such Note as the date on which the principal of such Note or such installment of interest, as the case may be, is due and payable.

 

Subsidiary” of any Person means (i) a corporation more than 50% of the combined voting power of the outstanding Voting Stock of which is owned, directly or indirectly, by such Person or by one or more other Subsidiaries of such Person or by such Person and one or more Subsidiaries thereof or (ii) any other Person (other than a corporation) in which such Person, or one or more other Subsidiaries of such Person or such Person and one or more other Subsidiaries thereof, directly or indirectly, has at least a majority ownership and power to direct the policies, management and affairs thereof.

 

Successor Note” of any particular Note means every Note issued after, and evidencing all or a portion of the same debt as that evidenced by, such particular Note; and, for the purposes of this definition, any Note authenticated and delivered under Section 3.5 in exchange for or in lieu of a mutilated, destroyed, lost or stolen Note shall be deemed to evidence the same debt as the mutilated, destroyed, lost or stolen Note.

 

Taxes” has the meaning set forth in Section 11.9.

 

Transaction Documents” has the meaning set forth in Section 11.1.

 

Transfer Agent” means the agent designated by the Issuer (not including the Registrar) for the registration of transfer of securities as provided in Section 11.2.

 

Treasury Rate” means, with respect to any Redemption Date, the rate per annum equal to the semi-annual equivalent yield to maturity or interpolated maturity (on a day count basis) of the Comparable Treasury Issue, assuming a price for the Comparable Treasury Issue (expressed as a percentage of its principal amount) equal to the Comparable Treasury Price for such Redemption Date.

 

Trustee” means the Person named as the “Trustee” in the first paragraph of this instrument until a successor Trustee shall have been appointed pursuant to the applicable provisions of this Indenture, and thereafter “Trustee” shall mean such successor Trustee.

 

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United States” means the United States of America.

 

U.S. Dollar Equivalent” means, with respect to any monetary amount in a currency other than the U.S. Dollar, at any time for the determination thereof, the amount of U.S. Dollars obtained by converting such foreign currency involved in such computation into U.S. Dollars at the spot rate for the purchase of U.S. Dollars with the applicable foreign currency as quoted by Reuters at approximately 11:00 a.m. (New York time) on the date not more than two Business Days prior to such determination.

 

U.S. Global Notes” has the meaning specified in Section 2.1.

 

Vice President” when used with respect to the Issuer or any Guarantor, means any vice president, whether or not designated by a number or a word or words added before or after the title “vice president.”

 

Voting Stock” of a Person means all classes of Capital Stock of such Person then outstanding that are entitled (without regard to the occurrence of any contingency) to vote in the election of the directors of such Person, but excluding such classes of Capital Stock or other interests that are entitled, as a group in a separate cast, to appoint one director of such Person as representative of the minority shareholders.

 

Wholly Owned Subsidiary” of any Person means any entity owned by such Person of which at least 95% of the outstanding Capital Stock or other ownership interests (other than directors’ qualifying shares) of such entity shall at the time be owned by such Person or by one or more Wholly Owned Subsidiaries of such Person.

 

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Section 1.2.          Compliance Certificates and Opinions.

 

Upon any application or request by the Issuer or a Guarantor to the Trustee to take any action under any provision of this Indenture, the Issuer or such Guarantor shall furnish to the Trustee such certificates and opinions as may be required under this Indenture; provided, however, that such certificate and opinion shall not be required in the case of the initial issuance of Notes hereunder. Each such certificate or opinion, and any certificate evidencing a determination required to be made by the Issuer or a Guarantor under this Indenture, shall be given in the form of an Officer’s Certificate, if to be given by an officer of the Issuer or such Guarantor, or an Opinion of Counsel, if to be given by counsel, and shall comply with the requirements set forth in this Indenture.

 

Every certificate or opinion with respect to compliance by or on behalf of the Issuer or a Guarantor with a condition or covenant provided for in this Indenture shall include:

 

(1)               a statement that each individual signing such certificate or opinion has read such covenant or condition and the definitions herein relating thereto;

 

(2)               a brief statement as to the nature and scope of the examination or investigation upon which the statements or opinions contained in such certificate or opinion are based;

 

(3)               a statement that, in the opinion of each such individual, he has made such examination or investigation as is necessary to enable him or her to express an informed opinion as to whether or not such covenant or condition has been complied with; and

 

(4)               a statement as to whether, in the opinion of each such individual, such condition or covenant has been complied with.

 

Section 1.3.          Form of Documents Delivered to Trustee.

 

In any case where several matters are required to be certified by, or covered by an opinion of, any specified Person, it is not necessary that all such matters be certified by, or covered by the opinion of, only one such Person, or that they be so certified or covered by only one document, but one such Person may certify or give an opinion with respect to some matters and one or more other such Persons as to other matters, and any such Person may certify or give an opinion as to such matters in one or several documents.

 

Any certificate of an officer of the Issuer or a Guarantor may be based, insofar as it relates to legal matters, upon an Opinion of Counsel submitted therewith, unless such officer knows, or in the exercise of reasonable care should know, that the opinion with respect to the matters upon which his certificate is based is erroneous. Any Opinion of Counsel may be based, insofar as it relates to factual matters, upon a certificate of an officer or officers of the Issuer or a Guarantor submitted therewith stating the information on which counsel is relying, unless such counsel knows, or in the exercise of reasonable care should know, that the certificate with respect to such matters is erroneous.

 

Where any Person is required to make, give or execute two or more applications, requests, consents, certificates, statements, opinions or other instruments under this Indenture, they may, but need not, be consolidated and form one instrument.

 

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Section 1.4.          Acts of Holders; Record Date.

 

Any request, demand, authorization, direction, notice, consent, waiver or other action provided by this Indenture to be given or taken by Holders may be embodied in and evidenced by one or more instruments of substantially similar tenor signed by such Holders in person or by an agent duly appointed in writing; and, except as herein otherwise expressly provided, such action shall become effective when such instrument or instruments are delivered to the Trustee and, where it is hereby expressly required, to the Issuer. Such instrument or instruments (and the action embodied therein and evidenced thereby) are herein sometimes referred to as the “Act” of the Holders signing such instrument or instruments. Proof of execution of any such instrument or of a writing appointing any such agent shall be sufficient for any purpose of this Indenture and (subject to Section 6.1) conclusive in favor of the Trustee and the Issuer, if made in the manner provided in this Section.

 

The fact and date of the execution by any Person of any such instrument or writing pursuant to this Section 1.4 may be proved by the affidavit of a witness of such execution or by a certificate of a notary public or other officer authorized by law to take acknowledgments of deeds, certifying that the individual signing such instrument or writing acknowledged to him or her the execution thereof. Where such execution is by a signer acting in a capacity other than his individual capacity, such certificate or affidavit shall also constitute sufficient proof of his authority. The fact and date of the execution of any such instrument or writing, or the authority of the Person executing the same, may also be proved in any other manner which the Trustee deems sufficient.

 

The ownership of Notes shall be proved by the Note Register.

 

Any request, demand, authorization, direction, notice, consent, waiver or other Act of the Holder of any Note shall bind every future Holder of the same Note and the Holder of every Note issued upon the registration of transfer thereof or in exchange therefor or in lieu thereof in respect of anything done, omitted or suffered to be done by the Trustee or the Issuer in reliance thereon, whether or not notation of such action is made upon such Note.

 

The Issuer may set any day as a record date for the purpose of determining the Holders of Outstanding Notes entitled to give, make or take any request, demand, authorization, direction, notice, consent, waiver or other action provided or permitted by this Indenture to be given, made or taken by Holders of Notes, provided that the Issuer may not set a record date for, and the provisions of this paragraph shall not apply with respect to, the giving or making of any notice, declaration, request or direction referred to in the next paragraph. If not set by the Issuer prior to the first solicitation of a Holder made by any Person in respect of any such matter referred to in the foregoing sentence, the record date for any such matter shall be the 30th day (or, if later, the date of the most recent list of Holders required to be provided pursuant to Section 7.1) prior to such first solicitation. If any record date is set pursuant to this paragraph, the Holders of Outstanding Notes on such record date, and no other Holders, shall be entitled to take the relevant action, whether or not such Holders remain Holders after such record date; provided that no such action shall be effective hereunder unless taken on or prior to the applicable Expiration Date by Holders of the requisite principal amount of Outstanding Notes on such record date.

 

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The Trustee may set any day as a record date for the purpose of determining the Holders of Outstanding Notes entitled to join in the giving or making of (i) any Notice of Default, (ii) any declaration of acceleration referred to in Section 5.1, (iii) any request to institute proceedings referred to in Section 5.6(2) or (iv) any direction referred to in Section 5.11. If any record date is set pursuant to this paragraph, the Holders of Outstanding Notes on such record date, and no other Holders, shall be entitled to join in such notice, declaration, request or direction, whether or not such Holders remain Holders after such record date; provided that no such action shall be effective hereunder unless taken on or prior to the applicable Expiration Date by Holders of the requisite principal amount of Outstanding Notes on such record date. Nothing in this paragraph shall be construed to prevent the Trustee from (i) giving or making any notice required to be made pursuant to the Trustee’s duties and obligations under this Indenture and (ii) setting a new record date for any action for which a record date has previously been set pursuant to this paragraph (whereupon the record date previously set shall automatically and with no action by any Person be cancelled and of no effect), and nothing in this paragraph shall be construed to render ineffective any action taken by Holders of the requisite principal amount of Outstanding Notes on the date such action is taken. Promptly after any record date is set pursuant to this paragraph, the Trustee, at the Issuer’s expense, shall cause notice of such record date, the proposed action by Holders and the applicable Expiration Date to be given to the Issuer in writing and to each Holder of Notes in the manner set forth in Section 1.6.

 

Nothing in this paragraph shall be construed to prevent the Issuer from setting a new record date for any action for which a record date has previously been set pursuant to this paragraph (whereupon the record date previously set shall automatically and with no action by any Person be cancelled and of no effect), and nothing in this paragraph shall be construed to render ineffective any action taken by Holders of the requisite principal amount of Outstanding Notes on the date such action is taken. Promptly after any record date is set pursuant to this paragraph, the Issuer, at its own expense, shall cause notice of such record date, the proposed action by Holders and the applicable Expiration Date to be given to the Trustee in writing and to each Holder of Notes in the manner set forth in Section 1.6.

 

With respect to any record date set pursuant to this Section, the party hereto which sets such record dates may designate any day as the “Expiration Date,” and from time to time may change the Expiration Date to any earlier or later day; provided that no such change shall be effective unless notice of the proposed new Expiration Date is given to the other party hereto in writing, and to each Holder of Notes in the manner set forth in Section 1.6, on or prior to the existing Expiration Date. If an Expiration Date is not designated with respect to any record date set pursuant to this Section, the party hereto which set such record date shall be deemed to have initially designated the 180th day after such record date as the Expiration Date with respect thereto, subject to its right to change the Expiration Date as provided in this paragraph. Notwithstanding the foregoing, no Expiration Date shall be later than the 180th day after the applicable record date.

 

Without limiting the foregoing, a Holder entitled hereunder to take any action hereunder with regard to any particular Note may do so with regard to all or any part of the principal amount of such Note or by one or more duly appointed agents each of which may do so pursuant to such appointment with regard to all or any part of such principal amount.

 

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Section 1.5.          Notices, Etc., to Trustee, the Paying Agents and the Issuer.

 

Any request, demand, authorization, direction, notice, consent, waiver or Act of Holders or other document provided or permitted by this Indenture to be made upon, given or furnished to, or filed with:

 

(1)               the Trustee or any Agent by any Holder or by the Issuer or the Guarantor shall be sufficient for every purpose hereunder if made, given, furnished or filed, in writing in English or accompanied by a certified translation to English, to or with the Trustee at The Bank of New York Mellon, 240 Greenwich Street, New York, New York 10286, United States, Attention: Global Corporate Trust, Fax: (212) 815-5630, and such other offices as the Trustee may designate from time to time or at any other address previously furnished in writing to the Holders, the Issuer by the Trustee;

 

(2)              the Principal Paying Agent by the Trustee, the Issuer or any Holder shall be sufficient for every purpose hereunder (except as otherwise expressly provided herein) if in writing and mailed, first class postage prepaid, to the Principal Paying Agent addressed to it at 240 Greenwich Street, New York, New York 10286, United States, Attention: Global Corporate Trust, or at any other address previously furnished in writing to the Trustee by the Principal Paying Agent;

 

(3)             the Issuer by the Trustee or by any Holder shall be sufficient for every purpose hereunder (except as otherwise expressly provided herein) if in writing and mailed, first-class postage prepaid, to the Issuer addressed to it at 37A, Avenue J.F. Kennedy, L-1855, Luxembourg, Grand Duchy of Luxembourg, Attention: Rodrigo Menck (Group Chief Financial Officer), or at any other address previously furnished in writing to the Trustee by the Issuer;

 

(4)             Nexa CJM by the Trustee or by any Holder shall be sufficient for every purpose hereunder (except as otherwise expressly provided herein) if in writing and mailed, first-class postage prepaid, to Nexa CJM addressed to it at Carretera Central Km 9.5, desvío a Huachipa, Lurigancho-Chosica, Provincia y Departamento de Lima, Peru, Attention: Rodrigo Menck (Group Chief Financial Officer), or at any other address previously furnished in writing to the Trustee by Nexa CJM;

 

(5)             Nexa Peru by the Trustee or by any Holder shall be sufficient for every purpose hereunder (except as otherwise expressly provided herein) if in writing and mailed, first-class postage prepaid, to Nexa Peru addressed to it at Avenida San Borja Norte 523, Lima, Peru, Attention: Rodrigo Menck (Group Chief Financial Officer), or at any other address previously furnished in writing to the Trustee by Nexa Peru; and

 

(6)             Nexa Brazil by the Trustee or by any Holder shall be sufficient for every purpose hereunder (except as otherwise expressly provided herein) if in writing and mailed, first-class postage prepaid, to Nexa Brazil addressed to it at Av. Engenheiro Luis Carlos Berrini, 105, São Paulo, SP 04571-010, Brazil, Attention: Rodrigo Menck (Treasurer), or at any other address previously furnished in writing to the Trustee by Nexa Brazil.

 

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Section 1.6.          Notice to Holders; Waiver.

 

Where this Indenture provides for notice to Holders of any event, such notice shall be sufficiently given (unless otherwise herein expressly provided) if (i) in the case of a Global Note, in writing by electronic mail, facsimile and/or by first-class mail to the Depositary, and (ii) in the case of securities other than Global Notes, in writing and mailed, first-class postage prepaid, to each Holder affected by such event, at his address as it appears in the Note Register on the Business Day immediately preceding the date of mailing, which shall be not later than the latest date (if any), and not earlier than the earliest date (if any), prescribed for the giving of such notice. In any case where notice to Holders is given by mail, neither the failure to mail such notice, nor any defect in any notice so mailed, to any particular Holder shall affect the sufficiency of such notice with respect to other Holders. Where this Indenture provides for notice in any manner, such notice may be waived in writing by the Person entitled to receive such notice, either before or after the event, and such waiver shall be the equivalent of such notice. Waivers of notice by Holders shall be filed with the Trustee, but such filing shall not be a condition precedent to the validity of any action taken in reliance upon such waiver.

 

In case by reason of the suspension of regular mail service or by reason of any other cause it shall be impracticable to give such notice by mail, then such notification as shall be made with the approval of the Trustee shall constitute a sufficient notification for every purpose hereunder.

 

Any obligation the Issuer (and the Paying Agents on its behalf) may have to publish a notice to Holders shall have been met upon delivery of the notice to the Depositary.

 

Section 1.7.          Effect of Headings and Table of Contents.

 

The Article and Section headings herein and the Table of Contents are for convenience only and shall not affect the construction hereof.

 

Section 1.8.          Successors and Assigns.

 

All covenants and agreements in this Indenture by each of the Issuer and the Guarantors shall bind its successors and assigns, whether so expressed or not.

 

Section 1.9.          Separability Clause.

 

In case any provision in this Indenture or in the Notes or in the Guarantees shall be invalid, illegal or unenforceable, the validity, legality and enforceability of the remaining provisions of each of this Indenture, the Notes or the Guarantees shall not in any way be affected or impaired thereby.

 

Section 1.10.       Benefits of Indenture.

 

Nothing in this Indenture or in the Notes, express or implied, shall give to any Person, other than the parties hereto and their successors hereunder and the Holders of Notes, any benefit or any legal or equitable right, remedy or claim under this Indenture, the Notes or the Guarantees.

 

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Section 1.11.       Governing Law.

 

THIS INDENTURE, THE NOTES AND THE GUARANTEES SHALL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK, without regard to conflicts of laws principles thereof. For the purposes of paragraph 2 of article 9 of the Brazilian Decree-Law No. 4,567, dated September 4, 1942, as amended, the Trustee shall be deemed the “proponent” of the transactions contemplated by this Indenture. Articles 470-1 through 470-19 of the Luxembourg law dated August 10, 1915 on commercial companies, as amended, which set the provisions related to the representation of the Holders of the Notes, are not applicable to the Notes or the Guarantees.

 

EACH OF THE PARTIES HERETO HEREBY IRREVOCABLY WAIVES, TO THE FULLEST EXTENT PERMITTED BY APPLICABLE LAW, ANY AND ALL RIGHT TO TRIAL BY JURY IN ANY LEGAL PROCEEDING ARISING OUT OF OR RELATING TO THIS INDENTURE, THE NOTES OR THE TRANSACTION CONTEMPLATED HEREBY.

 

Section 1.12.       Legal Holidays.

 

In any case where any Interest Payment Date, Redemption Date or Stated Maturity of any Note shall not be a Business Day, then (notwithstanding any other provision of this Indenture, the Notes or the Guarantees) payment of interest or principal (and premium, if any) need not be made on such date, but may be made on the next succeeding Business Day with the same force and effect as if made on the Interest Payment Date or Redemption Date, or at the Stated Maturity, provided that no interest shall accrue on account of such delay for the period from and after such Interest Payment Date or Redemption Date or Stated Maturity, as the case may be.

 

Section 1.13.       Consent to Jurisdiction and Service of Process.

 

(a)               Each of the Issuer and the Guarantors agrees that any suit, action or proceeding against it brought by any Holder or the Trustee arising out of or based upon this Indenture, the Notes or the Guarantees may be instituted in any state or Federal court in the Borough of Manhattan in The City of New York, New York, and waives any objection which it may now or hereafter have to the laying of venue of any such proceeding, and irrevocably submits to the non-exclusive jurisdiction of such courts in any suit, action or proceeding.

 

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(b)               By the execution and delivery of this Indenture or any amendment or supplement hereto, each of the Issuer and the Guarantors (i) acknowledges that it has, by separate written instrument, designated and appointed Cogency Global Inc. currently located at 122 East 42nd Street, 18th Floor, New York, NY 10168, as its authorized agent upon which process may be served in any suit, action or proceeding with respect to, arising out of, or relating to, the Notes, this Indenture or the Guarantees, that may be instituted in any Federal or state court in the State of New York, The City of New York, the Borough of Manhattan, or brought under Federal or state securities laws or brought by the Trustee or the Paying Agent (whether in its individual capacity or in its capacity as Trustee or the Paying Agent, as the case may be, hereunder), and acknowledges that Cogency Global Inc. has accepted such designation, (ii) submits to the jurisdiction of any such court in any such suit, action or proceeding, and (iii) agrees that service of process upon Cogency Global Inc. shall be deemed in every respect effective service of process upon the Issuer and the Guarantors, as the case may be, in any such suit, action or proceeding. Each of the Issuer and the Guarantors further agrees to take any and all action, including the execution and filing of any and all such documents and instruments as may be necessary to continue such designation and appointment of Cogency Global Inc. in full force and effect so long as this Indenture shall be in full force and effect; provided that the Issuer and the Guarantors may and shall (to the extent Cogency Global Inc. ceases to be able to be served on the basis contemplated herein), by written notice to the Trustee, designate such additional or alternative agents for service of process under this Section 1.13 that (i) maintains an office located in the Borough of Manhattan, The City of New York in the State of New York, (ii) are either (x) counsel for the Issuer and the Guarantors or (y) a corporate service company which acts as agent for service of process for other persons in the ordinary course of its business and (iii) agrees to act as agent for service of process in accordance with this Section 1.13. Such notice shall identify the name of such agent for process and the address of such agent for process in the Borough of Manhattan, The City of New York, State of New York. Upon the request of any Holder, the Trustee shall deliver such information to such Holder. Notwithstanding the foregoing, there shall, at all times, be at least one agent for service of process for the Issuer and the Guarantors appointed and acting in accordance with this Section 1.13.

 

(c)               To the extent that the Issuer or the Guarantors has or hereafter may acquire any immunity from jurisdiction of any court or from any legal process (whether through service of notice, attachment prior to judgment, attachment in aid of execution, execution or otherwise) with respect to itself or its property, each of the Issuer and the Guarantors hereby irrevocably waives such immunity in respect of its obligations under this Indenture, the Notes and the Guarantees, to the fullest extent permitted by law.

 

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Section 1.14.       Currency of Account; Conversion of Currency; Foreign Exchange Restrictions.

 

(a)               U.S. Dollars are the sole currency of account and payment for all sums payable by the Issuer and the Guarantors under or in connection with the Notes, the Guarantees or this Indenture, including damages. Any amount received or recovered in a currency other than U.S. dollars (whether as a result of, or of the enforcement of, a judgment or order of a court of any jurisdiction, in the winding-up or dissolution of the Issuer or the Guarantors or otherwise) by any Holder of the Notes in respect of any sum expressed to be due to it from the Issuer or the Guarantors shall only constitute a discharge to the Issuer or the Guarantors, as the case may be, to the extent of the U.S. dollar amount which the recipient is able to purchase with the amount so received or recovered in that other currency on the date of that receipt or recovery (or, if it is not practicable to make that purchase on that date, on the first date on which it is practicable to do so). If that U.S. dollar amount is less than the U.S. dollar amount expressed to be due to the recipient under the Notes, the Issuer and the Guarantors shall, jointly and severally, indemnify it against any loss sustained by it as a result as set forth in Section 1.14(b). In any event, the Issuer and the Guarantors shall, jointly and severally, indemnify the recipient against the cost of making any such purchase. For the purposes of this Section 1.14, it will be sufficient for the Holder of a Note to certify in a satisfactory manner (indicating sources of information used) that it would have suffered a loss had an actual purchase of U.S. dollars been made with the amount so received in that other currency on the date of receipt or recovery (or, if a purchase of U.S. dollars on such date had not been practicable, on the first date on which it would have been practicable, it being required that the need for a change of date be certified in the manner mentioned above). The indemnities set forth in this Section 1.14 constitute separate and independent obligations from other obligations of the Issuer and the Guarantors, shall give rise to a separate and independent cause of action, shall apply irrespective of any indulgence granted by any Holder of the Notes and shall continue in full force and effect despite any other judgment, order, claim or proof for a liquidated amount in respect of any sum due under the Notes.

 

(b)               The Issuer and the Guarantors covenant and agree that the following provisions shall apply to conversion of currency in the case of the Notes, the Guarantees and this Indenture:

 

(i)                 (A)          if for the purpose of obtaining judgment in, or enforcing the judgment of, any court in any country, it becomes necessary to convert into a currency (the “judgment currency”) an amount due in any other currency (the “Base Currency”), then the conversion shall be made at the rate of exchange prevailing on the Business Day before the day on which the judgment is given or the order of enforcement is made, as the case may be (unless a court shall otherwise determine), and

 

(B)              if there is change in the rate of exchange prevailing between the Business Day before the day on which the judgment is given or an order of enforcement is made, as the case may be (or such other date as a court shall determine), and the date of receipt of the amount due, the Issuer or the Guarantors, as the case may be, will pay such additional (or, as the case may be, such lesser) amount, if any, as may be necessary so that the amount paid in the judgment currency when converted at the rate of exchange prevailing on the date of receipt will produce the amount in the Base Currency originally due;

 

(ii)              in the event of the winding-up of the Issuer or the Guarantors at any time while any amount or damages owing under the Notes, the Guarantees and this Indenture, or any judgment or order rendered in respect thereof, shall remain outstanding, the Issuer and the Guarantors shall, jointly and severally, indemnify and hold the Holders and the Trustee harmless against any deficiency arising or resulting from any variation in rates of exchange between (1) the date as of which the U.S. Dollar Equivalent of the amount due or contingently due under the Notes, the Guarantees and this Indenture (other than under this Subsection (b)(ii)) is calculated for the purposes of such winding-up and (2) the final date for the filing of proofs of claim in such winding-up. For the purpose of this subsection (b)(ii), the final date for the filing of proofs of claim in the winding-up of the Issuer or the Guarantors, as the case may be, shall be the date fixed by the liquidator or otherwise in accordance with the relevant provisions of applicable law as being the latest practicable date as at which liabilities of the Issuer or the Guarantors, as the case may be, may be ascertained for such winding-up prior to payment by the liquidator or otherwise in respect thereto;

 

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(iii)           the obligations contained in Subsections (a), (b)(i)(B) and (b)(ii) of this Section 1.14 shall constitute separate and independent obligations from the other obligations of the Issuer and the Guarantors under the terms of this Indenture, shall give rise to separate and independent causes of action against the Issuer and the Guarantors, shall apply irrespective of any waiver or extension granted by any Holder or the Trustee or either of them from time to time and shall continue in full force and effect notwithstanding any judgment or order or the filing of any proof of claim in the winding-up of the Issuer or the Guarantors for a liquidated sum in respect of amounts due hereunder (other than under Subsection (b)(ii) above) or under any such judgment or order. Any such deficiency as aforesaid shall be deemed to constitute a loss suffered by the Holders or the Trustee, as the case may be, and no proof or evidence of any actual loss shall be required by the Issuer or the Guarantors or the liquidator or otherwise or any of them. In the case of subsection (b)(ii) above, the amount of such deficiency shall not be deemed to be reduced by any variation in rates of exchange occurring between the said final date and the date of any liquidating distribution; and

 

(iv)             the term “rate(s) of exchange” shall mean the rate of exchange quoted by Reuters at 10:00 a.m. (New York time) for spot purchases of the Base Currency with the judgment currency other than the Base Currency referred to in Subsections (b)(i) and (b)(ii) above and includes any premiums and costs of exchange payable.

 

(c)               In the event that on any Interest Payment Date, the Maturity Date or Redemption Date, as the case may be, in respect of the Guarantee provided by a Guarantor, any restrictions or prohibition of access to the foreign exchange market of the jurisdiction of incorporation of a Guarantor exists, such Guarantor agrees to pay all amounts payable under the Notes and such Guarantee in the currency of the Notes by means of any legal procedure existing in such jurisdiction of incorporation (except commencing legal proceedings against the relevant Central Bank), on any due date for payment under the Notes, for the purchase of the currency of such Notes. All costs and taxes payable in connection with the procedures referred to in this Section 1.14 shall be borne by the relevant Guarantor.

 

(d)               Notwithstanding anything to the contrary contained herein, neither the Trustee nor the Principal Paying Agent shall have any liability for converting into U.S. Dollars any amount received by any Holder in a currency other than U.S. Dollars.

 

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Section 1.15.       Counterparts.

 

This Indenture may be executed in two or more counterparts, each of which shall be deemed to be an original, but all of which together shall constitute one and the same instrument. The words “execution,” signed,” “signature,” and words of like import in this Indenture or in any other certificate, agreement or document related to this Indenture shall include images of manually executed signatures transmitted by facsimile or other electronic format (including, without limitation, “pdf”, “tif” or “jpg”) and other electronic signatures (including, without limitation, DocuSign and AdobeSign). The use of electronic signatures and electronic records (including, without limitation, any contract or other record created, generated, sent, communicated, received, or stored by electronic means) shall be of the same legal effect, validity and enforceability as a manually executed signature or use of a paper-based recordkeeping system to the fullest extent permitted by applicable law, including, without limitation, the Federal Electronic Signatures in Global and National Commerce Act, the New York State Electronic Signatures and Records Act and any other applicable law, including, without limitation, any state law based on the Uniform Electronic Transactions Act or the Uniform Commercial Code.

 

Section 1.16.       Force Majeure.

 

In no event shall the Trustee or any Agent be responsible or liable for any failure or delay in the performance of its obligations hereunder arising out of or caused by, directly or indirectly, forces beyond its control, including, without limitation, strikes, work stoppages, accidents, acts of war or terrorism, civil or military disturbances, nuclear or natural catastrophes or acts of God, and interruptions, loss or malfunctions of utilities, communications or computer (software and hardware) services; it being understood that the Trustee or such Agent shall use reasonable efforts which are consistent with accepted practices in the banking industry to resume performance as soon as practicable under the circumstances.

 

Section 1.17.       U.S.A. PATRIOT Act.

 

In order to comply with the laws, rules, regulations and executive orders in effect from time to time applicable to banking institutions, including, without limitation, those relating to the funding of terrorist activities and money laundering, including Section 326 of the USA PATRIOT Act of the United States (“Applicable Law”), the Trustee and Agents are required to obtain, verify, record and update certain information relating to individuals and entities which maintain a business relationship with the Trustee and Agents. Accordingly, each of the parties agrees to provide to the Trustee and Agents, upon their request from time to time such identifying information and documentation as may be available for such party in order to enable the Trustee and Agents to comply with Applicable Law.

 

Section 1.18.       Anti-Money Laundering, Terrorism and Economic Sanctions.

 

(a)               The Trustee or any Agent may take and instruct any delegate to take any action which it in its sole discretion considers appropriate so as to comply with any applicable law, regulation, request of a public or regulatory authority or any internal group policy (including any “Know Your Client” and/or other compliance policy) which relates to the prevention of fraud, money laundering, terrorism or other criminal activities or the provision of financial and other services to sanctioned persons or entities. Such action may include but is not limited to the interception and investigation of transactions on the Issuer’s or any Guarantor’s accounts (particularly those involving the international transfer of funds) including the source of the intended recipient of funds paid into or out of the Issuer’s or any Guarantor’s accounts. None of the Trustee, any Agent or any delegate will be liable for any loss (whether direct or consequential and including, without limitation, loss of profit or interest) caused in whole or in part by any actions which are taken by the Trustee, any Agent or any delegate pursuant to this Section 1.18.

 

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(b)               The Issuer and each Guarantor covenants and represents, jointly and severally, that neither it nor any of their respective subsidiaries or their respective directors or officers, and, to the knowledge of the Issuer or any Guarantor, any of their affiliates are the target or subject of any sanctions enforced by the US Government, (including, without limitation, the Office of Foreign Assets Control of the US Department of the Treasury or the US Department of State), the United Nations Security Council, the European Union, Her Majesty’s Treasury, or other relevant sanctions authority (collectively “Sanctions”);

 

(c)               The Issuer and each Guarantor covenants and represents, jointly and severally, that neither it nor any of their respective subsidiaries or their respective directors or officers will directly or indirectly use any repayments/reimbursements made pursuant to this Indenture, (i) to fund or facilitate any activities of or business with any person who, at the time of such funding or facilitation, is the subject or target of Sanctions, (ii) to fund or facilitate any activities of or business with any country or territory that is the target or subject of Sanctions, or (iii) in any other manner that will result in a violation of Sanctions by any Person.

 

Section 1.19.       Effective Date.

 

This Indenture shall become effective on the date hereof and shall be binding upon the Issuer, the Guarantors, the Trustee, the Registrar, the Paying Agent and the Principal Paying Agent.

 

Article II

NOTE FORMS

 

Section 2.1.          Forms Generally.

 

The Notes, the Trustee’s certificates of authentication thereof and the Guarantees endorsed thereon shall be substantially in the forms set forth in this Article, with such appropriate legends, insertions, omissions, substitutions and other variations as are required or permitted by this Indenture, and may have such letters, numbers or other marks of identification and such legends or endorsements placed thereon as may be required to comply with the rules of any securities exchange or as may, consistently herewith, be determined by the officers executing such Notes or Guarantees, as the case may be, as evidenced by their execution of the Notes.

 

The definitive Notes and the Guarantees to be endorsed thereon shall be printed, lithographed or engraved or produced by any combination of these methods on steel engraved borders or may be produced in any other manner all as determined by the officers executing such Notes, as evidenced by their execution of such Notes or Guarantees, as the case may be.

 

In certain cases described elsewhere herein, the legends set forth in the first three paragraphs of Section 2.2 may be omitted from Notes issued hereunder.

 

Notes offered and sold in their initial distribution in reliance on Regulation S will be initially issued in the form of one or more Global Notes in fully registered form without interest coupons, substantially in the form of Note set forth in Section 2.2 and 2.3 (the “Regulation S Global Note”), which shall be registered in the name of the Depositary or its nominee and deposited with the Trustee, at its Corporate Trust Office, as custodian for the Depositary, duly executed by the Issuer and the Guarantors and authenticated by the Trustee as hereinafter provided, for credit by the Depositary to the respective accounts of the beneficial owners of the Notes represented thereby (or such other accounts as they may direct).

 

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Notes offered and sold in their initial distribution in reliance on Rule 144A shall be issued in the form of one or more Global Notes (collectively, and, together with their Successor Notes, the “Restricted Global Note”) in fully registered form without interest coupons, substantially in the form of Note set forth in Section 2.2 and 2.3, with such applicable legends as are provided for in Section 2.2, except as otherwise permitted herein. Such Restricted Global Note shall be registered in the name of the Depositary or its nominee and deposited with the Trustee, at its Corporate Trust Office, as custodian for the Depositary, duly executed by the Issuer and the Guarantors and authenticated by the Trustee as hereinafter provided, for credit by the Depositary to the respective accounts of beneficial owners of the Notes represented thereby (or such other accounts as they may direct). The aggregate principal amount of the Restricted Global Note may be increased or decreased from time to time by adjustments made on the records of the Trustee, as custodian for the Depositary, in connection with a corresponding decrease or increase in the aggregate principal amount of the Regulation S Global Note, as hereinafter provided.

 

Section 2.2.          Form of Face of Note.

 

[Include if Note is a Restricted Global Note — THIS NOTE (OR ITS PREDECESSOR) WAS ORIGINALLY ISSUED IN A TRANSACTION EXEMPT FROM REGISTRATION UNDER THE UNITED STATES SECURITIES ACT OF 1933, AS AMENDED, OR THE SECURITIES ACT, AND THIS NOTE MAY NOT BE REOFFERED, SOLD OR

 

OTHERWISE TRANSFERRED IN THE ABSENCE OF SUCH REGISTRATION OR AN APPLICABLE EXEMPTION THEREFROM. EACH PURCHASER OF THIS NOTE IS HEREBY NOTIFIED THAT THE SELLER OF THIS NOTE MAY BE RELYING ON THE EXEMPTION FROM THE PROVISIONS OF SECTION 5 OF THE SECURITIES ACT PROVIDED BY RULE 144A THEREUNDER. THE HOLDER OF THIS NOTE AGREES FOR THE BENEFIT OF THE ISSUER OR ANY SUBSIDIARY THAT (A) THIS NOTE MAY BE REOFFERED, RESOLD, PLEDGED OR OTHERWISE TRANSFERRED, ONLY (I) TO A PERSON WHOM THE SELLER REASONABLY BELIEVES IS A QUALIFIED INSTITUTIONAL BUYER (AS DEFINED IN RULE 144A UNDER THE SECURITIES ACT) IN A TRANSACTION MEETING THE REQUIREMENTS OF RULE 144A, (II) OUTSIDE THE UNITED STATES TO A PERSON THAT IS NOT A U.S. PERSON IN AN OFFSHORE TRANSACTION IN ACCORDANCE WITH RULE 904 UNDER THE SECURITIES ACT, (III) PURSUANT TO ANOTHER AVAILABLE EXEMPTION UNDER THE SECURITIES ACT, (IV) TO THE ISSUER OR ANY SUBSIDIARY OF THE ISSUER OR (V) PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT, IN EACH OF CASES (I) THROUGH (V) IN ACCORDANCE WITH ANY APPLICABLE SECURITIES LAWS OF ANY STATE OF THE UNITED STATES; AND (B) THE HOLDER WILL, AND EACH SUBSEQUENT HOLDER IS REQUIRED TO, NOTIFY ANY PURCHASER OF THIS NOTE FROM IT OF THE RESALE RESTRICTIONS REFERRED TO IN (A) ABOVE. THIS LEGEND MAY ONLY BE REMOVED AT THE OPTION OF THE ISSUER.]

 

[Include if Note is a Regulation S Global Note — THIS NOTE (OR ITS PREDECESSOR) WAS ORIGINALLY ISSUED IN A TRANSACTION EXEMPT FROM REGISTRATION UNDER THE UNITED STATES SECURITIES ACT OF 1933, AS AMENDED, OR THE SECURITIES ACT, AND MAY NOT BE TRANSFERRED IN THE UNITED STATES OR TO, OR FOR THE ACCOUNT OR BENEFIT OF, ANY U.S. PERSON EXCEPT PURSUANT TO AN AVAILABLE EXEMPTION FROM THE REGISTRATION REQUIREMENTS OF THE SECURITIES ACT AND ALL APPLICABLE STATE SECURITIES LAWS. TERMS USED ABOVE HAVE THE MEANINGS GIVEN TO THEM IN REGULATION S UNDER THE SECURITIES ACT.]

 

26

 

 

NEXA RESOURCES S.A.
(organized under the laws of the Grand Duchy of Luxembourg)

 

[REGULATION S GLOBAL NOTE/RESTRICTED GLOBAL NOTE] [Delete as appropriate for either Regulation S Global Security or Restricted Global Security]
representing
U.S.$[                          ]

 

6.500% NOTES DUE 2028
guaranteed by
NEXA RESOURCES CAJAMARQUILLA S.A.
NEXA RESOURCES PERU S.A.A.
and
NEXA RECURSOS MINERAIS S.A.

 

ISIN Number: [144A: US65290DAA19] [REG S: USL67359AA48]
CUSIP Number: [144A: 65290D AA1] [REG S: L67359 AA4]
Common Code: [144A: 219373309] [REG S: 219373368]

[Delete as appropriate for either Regulation S Global Security or Restricted Global Security]

                          

 

Nexa Resources S.A., a validly organized public limited liability company validly organized under the laws of the Grand Duchy of Luxembourg having its registered office at 37A Avenue J.F. Kennedy, L-1855, Luxembourg, Grand Duchy of Luxembourg and registered with the Registre de Commerce et des Sociétés in Luxembourg under number B 185.489 (herein called the “Issuer,” which term includes any successor Person under the Indenture hereinafter referred to), for value received, hereby promises to pay to Cede & Co. or its registered assigns, the principal sum of Dollars [include if Note is a Global Note — (or such other Principal Sum as is noted in the records of the Custodian for the Depositary as being the Principal Amount of this Regulation S Global Note/Restricted Global Note for the time being)] on January 18, 2028, and to pay interest thereon from June 18, 2020, or from the most recent Interest Payment Date to which interest has been paid or duly provided for, semi-annually on January 18 and June 18 in each year, commencing on January 18, 2021, at the rate of 6.500% per annum, until the principal hereof is paid or made available for payment. The interest so payable, and punctually paid or duly provided for, on any Interest Payment Date will, as provided in such Indenture, be paid to the Person in whose name this Note (or one or more Predecessor Notes) is registered at the close of business on the Regular Record Date for such interest, which shall be two calendar days prior to payment (whether or not a Business Day), as the case may be, next preceding such Interest Payment Date. Any such interest not so punctually paid or duly provided for will forthwith cease to be payable to the Holder on such Regular Record Date and may either be paid to the Person in whose name this Note (or one or more Predecessor Notes) is registered at the close of business on a Special Record Date for the payment of such Defaulted Interest to be fixed by the Trustee, notice whereof shall be given to Holders of Notes not less than 10 days prior to such Special Record Date, or be paid at any time in any other lawful manner not inconsistent with the requirements of any securities exchange on which the Notes may be listed, and upon such notice as may be required by such exchange, all as more fully provided in said Indenture. In addition, the Issuer will pay to the Holder of this Note such Additional Amounts as may become payable under Section 11.9 of the Indenture.

 

27

 

 

In the case of a default in payment of principal and premium, if any, upon acceleration or repayment, interest shall be payable pursuant to the preceding paragraph on such overdue principal (and premium, if any), such interest shall be payable on demand and, if not so paid on demand, such interest shall itself bear interest at the rate per annum stated above plus 1% (to the extent that the payment of such interest shall be legally enforceable), and shall accrue from the date such principal and/or premium, as the case may be, was due and payable to the date payment of such interest has been made or duly provided for, and such interest on unpaid interest shall also be payable on demand.

 

Payment of the principal of (and premium, if any) and interest on this Note will be made at the Corporate Trust Office of the Trustee, at the offices of a Paying Agent, at the office or agency of the Issuer maintained for that purpose in The City of New York, New York, and at any other office or agency maintained by the Issuer for such purpose, in such coin or currency of the United States as at the time of payment is legal tender for payment of public and private debts; provided, however, that at the option of the Issuer payment of interest may be made by check mailed to the address of the Person entitled thereto as such address shall appear in the Note Register.

 

Reference is hereby made to the further provisions of this Note set forth on the reverse hereof, which further provisions shall for all purposes have the same effect as if set forth at this place.

 

Unless the certificate of authentication hereon has been executed by the Trustee referred to on the reverse hereof by manual or electronic signature, this Note shall not be entitled to any benefit under the Indenture or be valid or obligatory for any purpose.

 

28

 

 

 

IN WITNESS WHEREOF, the Issuer has caused this instrument to be duly executed.

 

NEXA RESOURCES S.A.
 
  By:  
    Name:
    Title:
 
  By:  
    Name:
    Title:

 

Section 2.3.          Form of Reverse of Note.

 

This Note is one of a duly authorized issue of Notes of the Issuer designated as its 6.500% Notes due 2028 (the “Notes”) issued under an Indenture, dated as of June 18, 2020 (herein called the “Indenture”), among the Issuer, the Guarantors named therein, and The Bank of New York Mellon, a New York banking corporation, as trustee (the “Trustee”), as principal paying agent (the “Principal Paying Agent” and any other paying agents to be appointed hereunder, the “Paying Agents”), as transfer agent (the “Transfer Agent”) and registrar (the “Registrar”). Reference is hereby made to the Indenture and all indentures supplemental thereto for a statement of the respective rights, limitations of rights, duties and immunities thereunder of the Issuer, the Guarantors, the Trustee, the Transfer Agent and the Notes are, and are to be, authenticated and delivered. Terms used but not defined in this Note are defined in the Indenture.

 

As provided in the Indenture and subject to certain limitations therein set forth, the obligations of the Issuer under the Indenture and this Note are guaranteed pursuant to the Guarantees set forth in the Indenture. Each Holder, by holding this Note, agrees to all of the terms and provisions of said Guarantees. Reference is hereby made to the Indenture for a statement of the respective rights, limitations of rights, duties and obligations thereunder of the Guarantors, the Trustee and the Holders.

 

The Issuer may from time to time, without the consent of the Holders of the Notes, create and issue Additional Notes having the same terms and conditions as the Notes in all respects, except that the issue date, the issue price and the first payment of interest thereon may differ; provided, however, that unless the Additional Notes are treated as part of the same “issue” of debt instruments as the original series or are issued pursuant to a “qualified reopening” of the original series, or are issued with no more than a de minimis amount of original issue discount, in each case for U.S. federal income tax purposes the additional notes will have a separate CUSIP, or ISIN number. Additional Notes shall be consolidated with and shall form a single series and vote together with the previously issued Notes for all purposes hereof.

 

29

 

 

If as a result of any Change of Law (as defined in the Indenture): (i) the Issuer or a Guarantor is or would be required on the next succeeding Interest Payment Date to pay any Additional Amounts referred to in Section 11.9 of the Indenture; or (ii) the issuers/borrowers of certain intercompany debt are or would be required on the next succeeding Interest Payment Date to pay Brazilian withholding taxes in excess of a general rate of 15%, or 25% in case of amounts paid to residents of countries which do not impose any income tax or which impose it at a maximum rate lower than 20% (or 17% if the relevant jurisdiction is committed to adopt international standards on tax transparency) or where the laws of that country or location impose restrictions on the disclosure of (x) shareholding composition; (y) the ownership of the investment; or (z) the beneficial ownership of income paid to non-resident persons, pursuant to Law No. 9,779, dated January 19, 1999; provided that, such requirement to pay such taxes in excess of such rate was not caused by, or otherwise the result of, whether directly or indirectly, wholly or in part, any amendment to the intercompany debt, and in either case, the payment of such excess amounts cannot be avoided by the use of any reasonable measures available to the Issuer or a Guarantor, the Notes may be repurchased, by the Issuer at the option of the Issuer or a Guarantor, in whole but not in part, upon not less than 30 nor more than 90 days’ notice to the Holders, which notice will be published, at any time following such Change of Law at a repurchase price equal to the principal amount thereof, plus accrued and unpaid interest, if any, to the date fixed for repurchase.

 

The Issuer or a Guarantor will also pay to Holders of the Notes on the Redemption Date any Additional Amounts which are payable. Following such repurchase, the Notes will be cancelled, or remain Outstanding, at the Issuer’s or a Guarantor’s election. Prior to the delivery of any notice of repurchase in accordance with the foregoing, the Issuer or a Guarantor shall deliver to the Trustee and the Principal Paying Agent an Officer’s Certificate stating that the Issuer or a Guarantor, as the case may be, is entitled to effect such repurchase based on an Opinion of Counsel or written advice of a qualified tax expert, that the Issuer or a Guarantor has or will, or there is a substantial probability that the Issuer or a Guarantor has or will, become obligated to pay such Additional Amounts as a result of such Change of Law. Such notice, once delivered by the Issuer or a Guarantor to the Trustee, will be irrevocable.

 

At any time before October 18, 2027 (which is the date that is three months prior to maturity of the notes (the “Par Call Date”)), the Issuer or a Guarantor has the right to redeem the Notes, in whole or in part and from time to time, at a redemption price equal to the greater of (1) 100% of the principal amount of the Notes being redeemed and (2) the sum of the present values of the remaining scheduled payments of principal and interest on the Notes being redeemed that would be due if the Notes matured on the Par Call Date (inclusive of interest accrued to the redemption date), discounted to the Redemption Date on a semi-annual basis (assuming a 360-day year consisting of twelve 30-day months) at the Treasury Rate plus 50 basis points, and in the case of clause (1) only, accrued and unpaid interest on the principal amount of the Notes being redeemed to, but excluding, such Redemption Date.

 

At any time on or after the Par Call Date, the Issuer or a Guarantor has the right to redeem the Notes, in whole or in part and from time to time, at a redemption price equal to 100% of the principal amount of the Notes being redeemed plus accrued and unpaid interest on the principal amount of the Notes being redeemed to, but excluding, such Redemption Date.

 

The Issuer, any Guarantor or any of their respective Affiliates may at any time repurchase the Notes at any price in the open market or otherwise. The Issuer, any Guarantor or any of their respective Affiliates may hold or resell the Notes it purchases or may surrender them to the Trustee or an Agent for cancellation.

 

30

 

 

[Include if Note is a Regulation S Global Note — If the holder of a beneficial interest in this Regulation S Global Note at any time wishes to transfer such interest to a Person who wishes to take delivery thereof in the form of a beneficial interest in the Restricted Global Note, such transfer may be effected, subject to the rules and procedures of the Depositary, Euroclear and Clearstream, in each case to the extent applicable and as in effect from time to time, only in accordance with the terms of this paragraph. Upon receipt by the Trustee, as Registrar, of (A) written instructions given by or on behalf of the Depositary in accordance with the rules and procedures of the Depositary, Euroclear and Clearstream, in each case to the extent applicable and as in effect from time to time directing the Trustee to credit or cause to be credited to a specified Agent Member’s account a beneficial interest in the Restricted Global Note in a specified principal amount and to cause to be debited from another specified Agent Member’s account a beneficial interest in this Regulation S Global Note in an equal principal amount; and (B) a certificate in substantially the form set forth in Exhibit B to the Indenture signed by or on behalf of the Agent Member holding such beneficial interest in this Regulation S Global Note, the Trustee, as Registrar, shall reduce the principal amount of this Regulation S Global Note and increase the principal amount of the Restricted Global Note by such specified principal amount.]

 

[Include if Note is a Restricted Global Note — If the holder of a beneficial interest in this Restricted Global Note wishes at any time to transfer such interest to a Person who wishes to take delivery thereof in the form of a beneficial interest in the Regulation S Global Note, such transfer may be effected, subject to the rules and procedures of the Depositary, Euroclear and Clearstream, in each case to the extent applicable and as in effect from time to time, only in accordance with the terms of this paragraph. Upon receipt by the Trustee, as Registrar of:

 

(A)            written instructions given by or on behalf of the Depositary in accordance with the rules and procedures of the Depositary, Euroclear and Clearstream, in each case to the extent applicable and as in effect from time to time directing the Trustee to credit or cause to be credited to a specified Agent Member’s account a beneficial interest in the Regulation S Global Note in a specified principal amount and to cause to be debited from another specified Agent Member’s account a beneficial interest in the Restricted Global Note in an equal principal amount; and

 

(B)              a certificate in substantially the form set forth in Exhibit A of the Indenture signed by or on behalf of the Agent Member holding such beneficial interest in this Restricted Global Note,

 

the Trustee, as Registrar, shall reduce the principal amount of this Restricted Global Note, and increase the principal amount of the Regulation S Global Note by such specified principal amount.]

 

The Notes do not have the benefit of any sinking fund obligations.

 

In the event of redemption or purchase of this Note in part only, a new Note or Notes of like tenor for the unredeemed or unpurchased portion hereof will be issued in the name of the Holder hereof upon the cancellation hereof.

 

31

 

 

If an Event of Default shall occur and be continuing, the principal of all the Notes may be declared due and payable in the manner and with the effect provided in the Indenture.

 

The Indenture contains provisions for defeasance at any time of (i) the entire indebtedness of this Note, or (ii) certain restrictive covenants and Events of Default with respect to this Note, in each case upon compliance with certain conditions set forth therein.

 

Unless the context otherwise requires, the Notes shall constitute one series for all purposes under the Indenture, including without limitation, amendments, waivers or redemption.

 

The Indenture permits, with certain exceptions as therein provided, the amendment thereof and the modification of the rights and obligations of the Issuer and the Guarantors and the rights of the Holders of the Notes under the Indenture at any time by the Issuer and the Trustee with the consent of the Holders of a majority in aggregate principal amount of the Notes at the time Outstanding. The Indenture also contains provisions permitting the Holders of specified percentages in aggregate principal amount of the Notes at the time Outstanding, on behalf of the Holders of all the Notes, to waive compliance by the Issuer or the Guarantors with certain provisions of the Indenture and certain past defaults under the Indenture and their consequences.

 

Any such consent or waiver by the Holder of this Note shall be conclusive and binding upon such Holder and upon all future Holders of this Note and of any Note issued upon the registration of transfer hereof or in exchange herefor or in lieu hereof, whether or not notation of such consent or waiver is made upon this Note.

 

No reference herein to the Indenture and no provision of this Note or of the Indenture shall alter or impair the obligation of the Issuer, which is absolute and unconditional, to pay the principal of (and premium, if any) and interest on this Note at the times, place and rate, and in the coin or currency, herein prescribed.

 

As provided in the Indenture and subject to certain limitations therein set forth, the transfer of this Note is registrable in the Note Register, upon surrender of this Note for registration of transfer at the office or agency of the Issuer in the Borough of Manhattan, The City of New York, New York, or of any of the Transfer Agents duly endorsed by, or accompanied by a written instrument of transfer in form satisfactory to the Issuer duly executed by, the Holder hereof or his attorney duly authorized in writing, and thereupon one or more new Notes, of authorized denominations and like tenor and for the same aggregate principal amount, will be issued to the designated transferee or transferees.

 

The Notes are issuable only in registered form without coupons in minimum denominations of U.S.$200,000 and integral multiples of U.S.$1,000 in excess thereof. As provided in the Indenture and subject to certain limitations therein set forth, Notes are exchangeable for a like tenor and aggregate principal amount of Notes of a different authorized denomination, as requested by the Holder surrendering the same.

 

32

 

 

No service charge shall be made for any such registration of transfer or exchange, but the Issuer or the Trustee may require payment of a sum sufficient to cover any tax or other governmental charge payable in connection therewith.

 

Prior to due presentment of this Note for registration of transfer, the Issuer, the Trustee, the Transfer Agents and any agent of the Issuer or the Trustee may treat the Person in whose name this Note is registered as the owner hereof for all purposes, whether or not this Note be overdue, and none of the Issuer, the Trustee or any such agent shall be affected by notice to the contrary.

 

Interest on this Note shall be computed on the basis of a 360-day year of twelve 30-day months each and, in the case of an incomplete month, on the number of days elapsed based on a 30-day month.

 

All terms used in this Note which are defined in the Indenture shall have the meanings assigned to them in the Indenture.

 

THE INDENTURE, THIS NOTE AND THE GUARANTEES SHALL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK, without regard to conflicts of laws principles thereof. For the purposes of paragraph 2 of article 9 of the Brazilian Decree-Law No. 4,567, dated September 4, 1942, as amended, the Trustee shall be deemed the “proponent” of the transactions contemplated by the Indenture. Articles 84 through 94-8 of the Luxembourg law dated August 10, 1915 on commercial companies, as amended, which set the provisions related to the representation of the Holders of the Notes, are not applicable to the Notes or the Guarantees.

 

The Issuer and the Guarantors agree that any suit, action or proceeding against any of them brought by any Holder or the Trustee arising out of or based upon this Indenture, the Notes or the Guarantees may be instituted in any state or Federal court in The City of New York, New York, and waive any objection which any of them may now or hereafter have to the laying of venue of any such proceeding, and irrevocably submits to the non-exclusive jurisdiction of such courts in any suit, action or proceeding.

 

The Issuer may change any Paying Agent, the Registrar or Transfer Agent; provided that the Issuer will maintain an office or agency where the Notes may be presented or surrendered for payment and for registration of transfer in the Borough of Manhattan, The City of New York. Upon any such change, the Issuer shall give written notice thereof to the Trustee, the Principal Paying Agent and the Holders.

 

U.S. dollars are the sole currency of account and payment for all sums payable by the Issuer and the Guarantors under or in connection with the Notes, the Guarantees or the Indenture, including damages. The Issuer and the Guarantors have agreed that the provisions of Section 1.14 of the Indenture shall apply to conversion of currency in the case of the Notes, the Guarantees and the Indenture. Among other things, Section 1.14 specifies that if there is a change in the rate of exchange prevailing between the Business Day before the day on which a judgment is given or an order of enforcement is made, as the case may be (or such other date as a court shall determine), and the date of receipt of the amount due, the Issuer or the relevant Guarantor, as the case may be, will pay such additional (or, as the case may be, such lesser) amount, if any, as may be necessary so that the amount paid in the judgment currency when converted at the rate of exchange prevailing on the date of receipt will produce the amount in the Base Currency originally due.

 

Each of the Issuer and the Guarantors has appointed Cogency Global Inc., currently located at 122 East 42nd Street, 18th Floor, New York, NY 10168, as its authorized agent upon which process may be served in any suit, or proceeding with respect to, arising out of, or relating to, this Note, the Indenture or the Guarantees, that may be instituted in any Federal or state court in the State of New York, The City of New York, the Borough of Manhattan, or brought under Federal or state securities laws and has agreed that there shall, at all times, be at least one agent for service of process for the Issuer and the Guarantors appointed and acting in accordance with the provisions of Section 1.13 of the Indenture relating to agent for service of process. To the extent that the Issuer or the Guarantors has or hereafter may acquire any immunity from jurisdiction of any court or from any legal process (whether through service of notice, attachment prior to judgment, attachment in aid of execution, execution or otherwise) with respect to itself or its property, each of the Issuer and the Guarantors has irrevocably waived such immunity in respect of its obligations under the Indenture, this Note and the Guarantees, to the fullest extent permitted by law.

 

33

 

 

 

Section 2.4.          Form of Trustee’s Certificate of Authentication.

 

This is one of the Notes with the Guarantees referred to in the within-mentioned Indenture.

 

THE BANK OF NEW YORK MELLON as Trustee
   
By:  
  Authorized Signatory
     
Dated:        

 

Each of the Guarantors, jointly and severally, guarantees the due and punctual payment of all sums from time to time payable in respect of the Notes as set forth in the Indenture.

 

NEXA RESOURCES CAJAMARQUILLA S.A.
   
By:  
  Name:
    Title:
   
By:  
    Name:
    Title:
 
  NEXA RESOURCES PERU S.A.A.
   
By:  
  Name:
    Title:
 
  By:  
    Name:
    Title:
   
  NEXA RECURSOS MINERAIS S.A.
   
  By:  
    Name:
    Title:
 
By:  
  Name:
    Title:

 

34

 

 

Article III

THE NOTES

 

Section 3.1.          Title and Terms.

 

On the Issue Date, the Trustee shall authenticate and deliver U.S.$500,000,000 aggregate principal amount of 6.500% Notes due 2028. The Issuer may from time to time, without the consent of the Holders of the Notes, create and issue Additional Notes having the same terms and conditions as the Notes in all respects, except that the issue date, the issue price and the first payment of interest thereon may differ; provided, however, that unless the Additional Notes are treated as part of the same “issue” of debt instruments as the original series or are issued pursuant to a “qualified reopening” of the original series, or are issued with no more than a de minimis amount of original issue discount, in each case for U.S. federal income tax purposes the additional notes will have a separate CUSIP, or ISIN number. Additional Notes shall be consolidated with and shall form a single series and vote together with the previously issued Notes for all purposes hereof.

 

The Notes shall be known and designated as the “6.500% Notes due 2028” of the Issuer. The Stated Maturity of the Notes shall be January 18, 2028. The Notes shall bear interest at the rate of 6.500% per annum, from June 18, 2020 or from the most recent Interest Payment Date thereafter to which interest has been paid or duly provided for, as the case may be, payable semiannually in arrears on January 18 and June 18, commencing January 18, 2021, until the principal thereof is paid or made available for payment.

 

In the case of a default in payment of principal and premium, if any, upon acceleration or redemption, interest (and Additional Amounts, if any) shall be payable pursuant to the second paragraph of this Section 3.1 on such overdue principal (and premium, if any), such interest shall be payable on demand and, if not so paid on demand, such interest shall itself bear interest at the rate per annum stated in the form of security contained herein plus 1% per annum (to the extent that the payment of such interest shall be legally enforceable), and shall accrue from the date such principal and/or premium, as the case may be, was due and payable to the date payment of such interest (and Additional Amounts, if any) has been made or duly provided for, and such interest on unpaid interest shall also be payable on demand.

 

The principal of and premium, if any, and interest on the Notes shall be payable at the Corporate Trust Office, the office of the Paying Agents and at any other office or agency maintained by the Issuer for such purpose; provided, however, that at the option of the Issuer upon five (5) Business Days’ notice to the applicable Paying Agent, payment of interest may be made by check mailed to the address of the Person entitled thereto as such address shall appear in the Note Register.

 

The Notes shall be redeemable or repurchasable as provided in Article XI. The Notes shall not have the benefit of any sinking fund obligations.

 

The Notes shall be subject to defeasance at the option of the Issuer as provided in Article XII.

 

Unless the context otherwise requires, the Notes shall constitute one series for all purposes under this Indenture, including, without limitation, amendments, waivers or redemptions

 

Section 3.2.          Denominations.

 

The Notes are issuable only in fully registered form, without coupons, in a minimum denomination of U.S.$200,000 and integral multiples of U.S.$1,000 in excess thereof.

 

Section 3.3.          Execution, Authentication, Delivery and Dating.

 

The Notes shall be executed on behalf of the Issuer by an authorized signatory or authorized signatories of the Issuer. The signature of any signatory on the Notes may be manual, electronic or facsimile.

 

Notes bearing the manual, electronic or facsimile signatures of individuals who were at any time the proper officers of the Issuer shall bind the Issuer, notwithstanding that such individuals or any of them have ceased to hold such offices prior to the authentication and delivery of such Notes or did not hold such offices at the date of such Notes.

 

35

 

 

At any time and from time to time after the execution and delivery of this Indenture, the Issuer may deliver Notes executed by the Issuer and having endorsed (by attachment or imprint) thereon the Guarantees executed as provided in Section 14.2 by the Guarantors, to the Trustee for authentication, together with an Issuer Order for the authentication and delivery of such Notes; and the Trustee in accordance with such Issuer Order shall authenticate and deliver such Notes as in this Indenture provided and not otherwise.

 

Each Note shall be dated the date of its authentication.

 

No Note or Guarantee shall be entitled to any benefit under this Indenture or be valid or obligatory for any purpose unless there appears on such Note a certificate of authentication substantially in the form provided for herein executed by the Trustee by manual or electronic signature, and such certificate upon any Note shall be conclusive evidence, and the only evidence, that such Note has been duly authenticated and delivered hereunder and that the Guarantees referred to therein have been duly executed and delivered hereunder.

 

Section 3.4.          Global Notes; Registration, Registration of Transfer and Exchange.

 

(a)               Global Notes. The provisions of clauses (1) through (7) below shall apply only to Global Notes:

 

(1)               each Global Note authenticated under this Indenture shall be registered in the name of the Depositary or a nominee thereof and delivered to the Depositary or a nominee thereof or custodian therefore, and each such Global Note shall constitute a single Note for all purposes of this Indenture;

 

(2)                notwithstanding any other provision in this Indenture, no Global Note may be exchanged in whole or in part for Notes registered, and no transfer of a Global Note in whole or in part may be registered, in the name of any Person other than the Depositary or a nominee thereof unless (A) the Depositary (i) has notified the Issuer that it is unwilling or unable to continue as Depositary for such Global Note and the Issuer thereupon fails to appoint a successor Depositary or (ii) has ceased to be a clearing agency registered under the Exchange Act, (B) the Issuer, at its option, notifies the Trustee in writing that it elects to cause the issuance of the Notes in definitive registered certificated form, or (C) an Event of Default has occurred and is continuing and the Registrar has received a written request from a beneficial owner of the Notes through an Agent Member to issue its proportionate interest in the Global Note in certificated form;

 

(3)             if any Global Note is to be exchanged for other Notes or cancelled in whole, it shall be surrendered by or on behalf of the Depositary or its nominee to the Trustee, as Registrar, for exchange or cancellation as provided in this Article III. If any Global Note is to be exchanged for other Notes or cancelled in part, or if another Note is to be exchanged in whole or in part for a beneficial interest in any Global Note, such Global Note shall be so surrendered for exchange or cancellation as provided in this Article III or, if the Trustee is acting as custodian for the Depositary or its nominee (or is party to a similar arrangement) with respect to such Global Note, the principal amount thereof shall be reduced or increased by an amount equal to the portion thereof to be so exchanged or cancelled, or the principal amount of such other Note to be so exchanged for a beneficial interest therein, as the case may be, in each case by means of an appropriate adjustment made on the records of the Trustee, whereupon the Trustee, in accordance with the Applicable Procedures, shall instruct the Depositary or its authorized representatives to make a corresponding adjustment to its records (including by crediting or debiting any Agent Member’s account as necessary to reflect any transfer or exchange of a beneficial interest pursuant to Section 3.4(c)). Upon any such surrender or adjustment of a Global Note, the Trustee shall, subject to Section 3.4(a)(2) and as otherwise provided in this Article III, authenticate and deliver any Notes issuable in exchange for such Global Note (or any portion thereof) to or upon the order of, and registered in such names as may be directed by, the Depositary or its authorized representative. Upon the request of the Trustee in connection with the occurrence of any of the events specified in the preceding paragraph, the Issuer shall promptly make available to the Trustee a reasonable supply of Notes that are not in the form of Global Notes. The Trustee shall be entitled to conclusively rely upon any order, direction or request of the Depositary or its authorized representative which is given or made pursuant to this Article III if such order, direction or request is given or made in accordance with the Applicable Procedures;

 

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(4)               every Note authenticated and delivered upon registration of transfer of, or in exchange for or in lieu of, a Global Note or any portion thereof, whether pursuant to this Article III or Section 10.5 or otherwise, shall be authenticated and delivered in the form of, and shall be, a Global Note, unless such Note is registered in the name of a Person other than the Depositary or a nominee thereof;

 

(5)              none of the Issuer, the Guarantors, the Trustee, any agent of the Trustee, any Paying Agent or the Registrar will have any responsibility or liability for any aspect of the Depositary’s records (or the records of the participant of such Depositary) relating to or payments made on account of beneficial ownership interests of a Global Note or for maintaining, supervising or reviewing any records of the Depositary relating to such beneficial ownership interests;

 

(6)               subject to the provisions in the legends required by Section 2.2 above, the registered Holder may grant proxies and otherwise authorize any Person, including Agent Members and Persons who may hold interests in Agent Members, to take any action that such Holder is entitled to take under this Indenture;

 

(7)               except as provided in Section 3.4(a)(2) herein, neither Agent Members nor any other Person on whose behalf Agent Members may act shall have any rights under this Indenture with respect to any Global Note held on their behalf by the Depositary or under the Global Note, and the Depositary may be treated by the Issuer, the Trustee and any agent of the Issuer or the Trustee as the absolute owner of such Global Note for all purposes whatsoever. Notwithstanding the foregoing, nothing herein shall prevent the Issuer, the Guarantors, the Trustee or any agent of the Issuer or the Trustee from giving effect to any written certification, proxy or other authorization furnished by the Depositary or impair, as between the Depositary and its Agent Members, the operation of customary practices governing the exercise of the rights of a Holder of any Note.

 

(b)               Registration, Registration of Transfer and Exchange and Legends. The Issuer shall cause to be kept at the Corporate Trust Office of the Trustee a register (the register maintained in such office and in any other office or agency designated pursuant to Section 11.2 being herein sometimes collectively referred to as the “Note Register”) in which, subject to such reasonable regulations as they may prescribe, the Issuer shall provide for the registration of Notes and of transfers and exchanges of Notes. The Trustee is hereby appointed “Registrar” for the purpose of registering Notes and transfers and exchanges of Notes as herein provided.

 

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Upon surrender for registration of transfer of any Note at an office or agency of the Issuer designated pursuant to Section 11.2 for such purpose in accordance with the terms hereof, the Issuer shall, subject to the other provisions of this Section 3.4, execute, and the Trustee shall, upon receipt of an Issuer Order, authenticate and deliver, in the name of the designated transferee or transferees, one or more new Notes of any authorized denominations and of a like tenor and aggregate principal amount and bearing the applicable legends set forth in Section 2.2.

 

Subject to Section 3.4(c), at the option of the Holder, Notes may be exchanged for other Notes of any authorized denominations and of a like tenor and aggregate principal amount and bearing the applicable legend set forth in Section 2.2, if any, each such new Note having the benefit of the Guarantees executed by the Guarantors, upon surrender of the Note to be exchanged at such office or agency. Whenever any Note is so surrendered for exchange, the Issuer shall execute, and the Trustee shall, upon receipt of an Issuer Order, authenticate and deliver, the Note which the Holder making the exchange is entitled to receive.

 

The Trustee shall have no obligation or duty to monitor, determine or inquire as to compliance with U.S. securities laws, including but not limited to any restrictions on transfer imposed under this Indenture or under applicable law with respect to any transfer of any interest in any Note (including any transfers between or among Agent Members or beneficial owners of interests in any Global Note) other than to require delivery of such certificates and other documentation or evidence as are expressly required by, and to do so if and when expressly required by the terms of, this Indenture, and to examine the same to determine substantial compliance solely as to form with the express requirements hereof. Neither the Trustee nor any Agent shall have any responsibility or liability for any actions taken or not taken by the Depositary.

 

All Notes and the Guarantees issued upon any registration of transfer or exchange of Notes shall be the valid obligations of the Issuer and the Guarantors, evidencing the same debt, and entitled to the same benefits under this Indenture, as the Notes and the Guarantees endorsed thereon, respectively, surrendered upon such registration of transfer or exchange.

 

Every Note presented or surrendered for registration of transfer or for exchange shall (if so required by the Issuer or the Trustee) be duly endorsed, or be accompanied by a written instrument of transfer in form satisfactory to the Issuer and the Registrar duly executed, by the Holder thereof or his attorney duly authorized in writing.

 

No service charge shall be made to the Holder for any registration of transfer or exchange of Notes, but the Issuer or the Trustee may require payment of a sum sufficient to cover any tax or other governmental charge that may be imposed in connection with any registration of transfer or exchange of Notes, other than exchanges pursuant to Section 3.4, 3.5 or 10.5.

 

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The Issuer and the Registrar shall not be required (i) to issue, register the transfer of or exchange any Note during a period beginning at the opening of business 15 days before the due date for any payment of principal in respect of the Notes selected for redemption under Section 4.6 and ending at the close of business on the day of such mailing, or (ii) to register the transfer of or exchange any Note so selected for redemption in whole or in part, except the unredeemed portion of any Note being redeemed in part.

 

All Notes, initially issued hereunder shall, upon issuance, bear the relevant legends specified in Section 2.2, if any, to be applied to such a Note and, in the case of the legend specifically required for the Restricted Global Note, such required legend shall not be removed unless the Issuer shall have delivered to the Trustee (and the Notes Registrar, if other than the Trustee) an Issuer Order which states that such Note may be issued without such legend thereon. If such legend has been removed from a Note as provided above, no other Note issued in exchange for all or any part of such Note shall bear such legend, unless the Issuer has reasonable cause to believe that such other Note is a “restricted security” within the meaning of Rule 144 of the Notes Act and instructs the Trustee to cause a legend to appear thereon:

 

(c)               Certain Transfers and Exchanges. Upon presentation for transfer or exchange of any Note at the office of the Trustee, as Registrar, located in The City of New York, accompanied by a written instrument of transfer or exchange in the form approved by the Issuer (it being understood that, until notice to the contrary is given to Holders of Notes, the Issuer shall be deemed to have approved the form of instrument of transfer or exchange, if any, printed on any Note), executed by the registered Holder, in person or by such Holder’s attorney thereunto duly authorized in writing, and upon compliance with this Section 3.4, such Note shall be transferred upon the Note Register, and a new Note shall be authenticated and issued in the name of the transferee. Notwithstanding any provision to the contrary herein or in the Notes, transfers of a Global Note, in whole or in part, and transfers of interests therein of the kind described in this Section 3.4 (c), shall only be made in accordance with this Section 3.4(c). Transfers and exchanges subject to this Section 3.4(c) shall also be subject to the other provisions of this Indenture that are not inconsistent with this Section 3.4(c).

 

(1)             General. A Global Note may not be transferred, in whole or in part, to any Person other than the Depositary or a nominee thereof, and no such transfer to any such other Person may be registered; provided, however, that this clause (1) shall not prohibit any transfer of a Note that is issued in exchange for a Global Note but is not itself a Global Note. No transfer of a Note to any Person shall be effective under this Indenture or the Notes unless and until such Note has been registered in the name of such Person. Nothing in this clause (1) shall prohibit or render ineffective any transfer of a beneficial interest in a Global Note effected in accordance with the other provisions of this Section 3.4(c).

 

(2)               Restricted Global Note to Regulation S Global Note. If the holder of a beneficial interest in the Restricted Global Note wishes at any time to transfer such interest to a Person who wishes to take delivery thereof in the form of a beneficial interest in the Regulation S Global Note, such transfer may be effected, subject to the rules and procedures of the Depositary, Euroclear and Clearstream, in each case to the extent applicable and as in effect from time to time (the “Applicable Procedures”), only in accordance with this clause (2). Upon receipt by the Trustee, as Registrar, of (A) written instructions given by or on behalf of the Depositary in accordance with the Applicable Procedures directing the Trustee to credit or cause to be credited to a specified Agent Member’s account a beneficial interest in the Regulation S Global Note in a specified principal amount and to cause to be debited from another specified Agent Member’s account a beneficial interest in the Restricted Global Note in an equal principal amount and (B) a certificate in substantially the form set forth in Exhibit A signed by or on behalf of the Agent Member holding such beneficial interest in the Restricted Global Note, the Trustee, as Registrar, shall reduce the principal amount of a Restricted Global Note, and increase the principal amount of the Regulation S Global Note by such specified principal amount as provided in Section 3.4(a)(3).

 

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(3)               Regulation S Global Note to Restricted Global Note. If the holder of a beneficial interest in the Regulation S Global Note at any time wishes to transfer such interest to a Person who wishes to take delivery thereof in the form of a beneficial interest in the Restricted Global Note, such transfer may be effected, subject to the Applicable Procedures, only in accordance with this clause (3). Upon receipt by the Trustee, as Registrar, of (A) written instructions given by or on behalf of the Depositary in accordance with the Applicable Procedures directing the Trustee to credit or cause to be credited to a specified Agent Member’s account a beneficial interest in the Restricted Global Note in a specified principal amount and to cause to be debited from another specified Agent Member’s account a beneficial interest in the Regulation S Global Note and (B) a certificate in substantially the form set forth in Exhibit B signed by or on behalf of the Agent Member holding such beneficial interest in the Regulation S Global Note, the Trustee, as Registrar, shall reduce the principal amount of such Regulation S Global Note and increase the principal amount of the Restricted Global Note by such specified principal amount as provided in Section 3.4(a)(3).

 

(4)               Non-Global Restricted Note to Global Note. If the holder of a Restricted Note (other than a Global Note) wishes at any time to transfer all or any portion of such Note to a Person who wishes to take delivery thereof in the form of a beneficial interest in the Restricted Global Note or the Regulation S Global Note, such transfer may be effected, subject to the Applicable Procedures, only in accordance with this clause (4). Upon receipt by the Trustee, as Registrar, of (A) such Note and written instructions given by or on behalf of such Holder as provided in Section 3.4(b) directing the Trustee to credit or cause to be credited to a specified Agent Member’s account a beneficial interest in the Restricted Global Note or the Regulation S Global Note, as the case may be, in a specified principal amount equal to the principal amount of the Restricted Note (or portion thereof) to be so transferred, and (B) an appropriately completed certificate substantially in the form set forth in Exhibit C-1 hereto, if the specified account is to be credited with a beneficial interest in the Restricted Global Note, or Exhibit C-2 hereto, if the specified account is to be credited with a beneficial interest in the Regulation S Global Note, signed by or on behalf of such Holder, then the Trustee, as Registrar, shall cancel such Restricted Note (and issue a new Note in respect of any untransferred portion thereof) as provided in Section 3.4(b) and increase the principal amount of the Restricted Global Note or Regulation S Global Note, as the case may be, by the specified principal amount as provided in Section 3.4(a)(3).

 

(5)               Non-Global Regulation S Note to Restricted Global Note or Regulation S Global Note. If the Holder of a Regulation S Note (other than a Global Note) wishes at any time to transfer all or any portion of such Note to a Person who wishes to take delivery thereof in the form of a beneficial interest in the Restricted Global Note or the Regulation S Global Note, as the case may be, such transfer may be effected only in accordance with this clause (5) and subject to the Applicable Procedures. Upon receipt by the Trustee, as Registrar, of (A) such Note and written instructions given by or on behalf of such Holder as provided in Section 3.4(b) directing the Trustee to credit or cause to be credited to a specified Agent Member’s account a beneficial interest in the Restricted Global Note or the Regulation S Global Note, as the case may be, in a principal amount equal to the principal amount of the Note (or portion thereof) to be so transferred, and (B)(i) with respect to a transfer which is to be delivered in the form of a beneficial interest in the Restricted Global Note, a certificate in substantially the form set forth in Exhibit D-l, signed by or on behalf of such Holder, and (ii) with respect to a transfer which is to be delivered in the form of a beneficial interest in the Regulation S Global Note, a certificate in substantially the form set forth in Exhibit D-2, signed by or on behalf of such Holder, then the Trustee, as Registrar, shall cancel such Note (and issue a new Note in respect of any untransferred portion thereof) as provided in Section 3.4(b) and increase the principal amount of the Restricted Global Note or the Regulation S Global Note, as the case may be, by the specified principal as provided in Section 3.4(a)(3).

 

Section 3.5.          Mutilated, Destroyed, Lost and Stolen Notes.

 

If any mutilated or defaced Note is surrendered to the Trustee, the Issuer shall execute and the Trustee shall, upon receipt of an Issuer Order, authenticate or cause to be authenticated and deliver in exchange therefore a new Note of like tenor and principal amount, having endorsed thereon the Guarantees executed by the Guarantors and bearing a number not contemporaneously outstanding.

 

If there shall be delivered to the Issuer and the Trustee (i) evidence to their satisfaction of the destruction, loss or theft of any Note and (ii) such security or indemnity as may be required by them to save each of them, the Guarantors and any agent of either of them harmless, then, in the absence of notice to the Issuer or the Trustee that such Note has been acquired by a bona fide purchaser, the Issuer shall execute and the Trustee shall, upon receipt of an Issuer Order, authenticate and deliver, in lieu of any such destroyed, lost or stolen Note, a new Note of like tenor and principal amount, having endorsed thereon the Guarantees executed by the Guarantors and bearing a number not contemporaneously outstanding.

 

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In case any such mutilated, defaced, destroyed, lost or stolen Note has become or is about to become due and payable, the Issuer may in its discretion, instead of issuing a new Note, pay such Note.

 

Upon the issuance of any new Note under this Section, the Issuer may require the payment of a sum sufficient to cover any tax or other governmental charge that may be imposed in relation thereto and any other expenses (including the fees and expenses of the Trustee, its counsel, the Registrar and the Paying Agents) connected therewith.

 

Every new Note issued pursuant to this Section in lieu of any destroyed, defaced, lost or stolen Note, and the Guarantees endorsed thereon, shall constitute an original additional contractual obligation of the Issuer and the Guarantors, respectively, whether or not the destroyed, lost or stolen Note shall be at any time enforceable by anyone, and shall be entitled to all the benefits of this Indenture equally and proportionately with any and all other Notes and Guarantees, respectively duly issued hereunder.

 

The provisions of this Section are exclusive and shall preclude (to the extent lawful) all other rights and remedies with respect to the replacement or payment of mutilated, destroyed, lost or stolen Notes.

 

Section 3.6.          Payment of Interest; Interest Rights Preserved.

 

Interest on any Note which is payable, and is punctually paid or duly provided for, on any Interest Payment Date shall be paid to the Person in whose name that Note (or one or more Predecessor Notes) is registered at the close of business on the Regular Record Date for such interest.

 

Any interest on any Note which is payable, but is not punctually paid or duly provided for, on any Interest Payment Date (herein called “Defaulted Interest”) shall (a) bear interest at the rate per annum stated in the form of Note included herein, (to the extent that the payment of such interest shall be legally enforceable), and (b) forthwith cease to be payable to the Holder on the relevant Regular Record Date by virtue of having been such Holder, and such Defaulted Interest may be paid by the Issuer, at its election in each case, as provided in clause (1) or (2) below:

 

(1)          the Issuer may elect to make payment of any Defaulted Interest to the Persons in whose names the Notes (or their respective Predecessor Notes) are registered at the close of business on a Special Record Date for the payment of such Defaulted Interest, which shall be fixed in the following manner. The Issuer shall notify the Trustee in writing of the amount of Defaulted Interest proposed to be paid on each Note and the date of the proposed payment, and at the same time the Issuer shall deposit with the Trustee an amount of money equal to the aggregate amount proposed to be paid in respect of such Defaulted Interest or shall make arrangements satisfactory to the Trustee for such deposit prior to the date of the proposed payment, such money when deposited to be held in trust for the benefit of the Persons entitled to such Defaulted Interest as in this clause provided.

 

Thereupon the Trustee shall fix a Special Record Date for the payment of such Defaulted Interest which shall be not more than 15 days and not less than 10 days prior to the date of the proposed payment and not less than 10 days after the receipt by the Trustee of the notice of the proposed payment. The Trustee shall promptly notify the Issuer of such Special Record Date and, in the name and at the expense of the Issuer, shall cause notice of the proposed payment of such Defaulted Interest and the Special Record Date therefore to be mailed, first- class postage prepaid, to each Holder at his address as it appears in the Note Register, not less than 10 days prior to such Special Record Date. Notice of the proposed payment of such Defaulted Interest and the Special Record Date therefore having been so mailed, such Defaulted Interest shall be paid to the Persons in whose names the Notes (or their respective Predecessor Notes) are registered at the close of business on such Special Record Date and shall no longer be payable pursuant to the following clause (2); and

 

(b)               the Issuer may make payment of any Defaulted Interest in any other lawful manner not inconsistent with the requirements of any securities exchange on which the Notes may be listed, and upon such notice as may be required by such exchange, if, after notice given by the Issuer to the Trustee of the proposed payment pursuant to this clause, such manner of payment shall be deemed practicable by the Trustee.

 

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Subject to the foregoing provisions of this Section, each Note delivered under this Indenture upon registration of transfer of or in exchange for or in lieu of any other Note shall carry the rights to interest accrued and unpaid, and to accrue, which were carried by such other Note.

 

Section 3.7.          Persons Deemed Owners.

 

Prior to due presentment of a Note for registration of transfer and the effective registration of such transfer by the Registrar, the Issuer, the Guarantors, the Trustee and any agent of the Issuer, the Guarantors or the Trustee may treat the Person in whose name such Note is registered as the owner of such Note for the purpose of receiving payment of principal of and premium, if any, and (subject to Section 3.6) interest on such Note and for all other purposes whatsoever, whether or not such Note be overdue, and none of the Issuer, the Guarantors, the Trustee or any agent of the Issuer, the Guarantors or the Trustee shall be liable for so treating such Holder.

 

Section 3.8.          Cancellation.

 

Except as provided for in Section 4.2 and 4.3, Notes surrendered for payment, redemption, registration of transfer or exchange shall, if surrendered to any Person other than the Trustee, be delivered to the Trustee and shall be promptly cancelled by it. The Issuer may at any time deliver to the Trustee for cancellation, accompanied by an Issuer Order, any Notes previously authenticated and delivered hereunder which the Issuer may have acquired in any manner whatsoever, and all Notes so delivered shall be promptly cancelled by the Trustee. No Notes shall be authenticated in lieu of or in exchange for any Notes cancelled as provided in this Section, except as expressly permitted by this Indenture. All cancelled Notes held by the Trustee shall be disposed of in accordance with its standard procedures or as directed by an Issuer Order; provided, however, that the Trustee shall not be required to destroy such Notes.

 

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Section 3.9.          Computation of Interest.

 

The amount of interest payable on the Notes for any interest period will be calculated by applying the rate of interest to the principal amount of such Note, on the basis of a year of 360 days consisting of 12 months of 30 days each and, in the case of an incomplete month, on the number of days elapsed based on a 30 day month provided, however, that Defaulted Interest shall be computed on the basis of a 365 or 366-day year, as the case may be, and the number of days actually elapsed.

 

Section 3.10.        CUSIP Numbers.

 

The Issuer shall in issuing the Notes use CUSIP numbers, and the Trustee shall use the applicable CUSIP number in notices of redemption or exchange as a convenience to the Holders; provided, that any such notice may state that no representation is made as to the accuracy or correctness of the CUSIP number or numbers printed in the notice or on the certificates representing the Notes and that reliance may be placed only on the other identification numbers printed on the certificates representing the Notes. The Issuer shall promptly notify the Trustee in writing of any change in CUSIP numbers.

 

Section 3.11.        Paying Agents; Discharge of Payment Obligations; Indemnity of Holders.

 

(a)               The Issuer may from time to time appoint one or more paying agents under this Indenture and the Notes. By its execution and delivery of this Indenture, the Issuer hereby initially designates and appoints The Bank of New York Mellon, as Principal Paying Agent. Subject to Section 11.3, the Issuer or a Guarantor may act as paying agent.

 

(b)               Unless the Issuer or a Guarantor shall be acting as paying agent as provided in Section 11.3, the Issuer shall, by 11:00 a.m. New York City time, no later than one Business Day prior to each Interest Payment Date, Redemption Date or Maturity Date on any Notes (whether on maturity, redemption or otherwise) (each, a “Payment Date”), deposit with the Principal Paying Agent in immediately available funds a sum sufficient to pay such principal, any premium, and interest when so becoming due (including any Additional Amounts). The Issuer shall request that the bank through which such payment is to be made agree to supply to the Principal Paying Agent in New York City by 11:00 a.m. (New York City time) two Business Days prior to the due date for any such payment an irrevocable confirmation (by authenticated SWIFT MT 100 Message) of its intention to make such payment. The Principal Paying Agent shall arrange with all other Paying Agents for the payment, from funds furnished by the Issuer or the Guarantors to the Principal Paying Agent pursuant to this Indenture, of the principal, and premium, if any, and interest (including Additional Amounts, if any) on the Notes and of the compensation of such Paying Agents for their services as such.

 

All Paying Agents will hold in trust, for the benefit of Holders or the Trustee, all money held by such Paying Agent for the payment of principal, or premium if any, of or interest on the Notes and shall notify the Trustee in writing of any default by the Issuer in making any such payment. The Issuer at any time may require a Paying Agent to pay all money held by it to the Trustee and to account for any funds disbursed by it. Upon complying with this Section 3.11 and the applicable provisions of Section 11.3, the Paying Agents shall have no further liability for the money delivered to the Trustee.

 

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(c)               Any payment to be made in respect of the Notes or the Guarantees by the Issuer or the Guarantors, as the case may be, to or to the order of any Paying Agent shall be in satisfaction pro tanto of the obligations of the Issuer under the Notes.

 

(d)               Each payment in full of principal, redemption amount, Additional Amounts and/or interest payable under this Indenture in respect of any Note made by or on behalf of the Issuer to or to the order of any Paying Agent in the manner specified in this Indenture on the date due shall be valid and effective to satisfy and discharge the obligation of the Issuer to make payment of principal, redemption amount, Additional Amounts and/or interest payable under this Indenture on such date, provided, however, that the liability of any Paying Agent hereunder shall not exceed any amounts paid to it by the Issuer, or held by it, on behalf of the Holders under this Indenture; and provided further that, in the event that there is a default by the Paying Agent or the Principal Paying Agent in any payment of principal, redemption amount, Additional Amounts and/or interest in respect of any Note in accordance with this Indenture, the Issuer and the Guarantors shall pay on demand such further amounts as will result in receipt by the Holder of such amounts as would have been received by it had no such default. This obligation constitutes a separate and independent obligation from the other obligations of the Issuer under the Notes and the Guarantors under the Guarantees, shall give rise to a separate and independent cause of action, will apply irrespective of any waiver granted by the Trustee and/or any Holder of Notes and shall continue in full force and effect despite any judgment, order, claim, or proof for a liquidated amount in respect of any sum due under this Indenture, the Notes or any judgment or order.

 

Article IV

 

REDEMPTION OF NOTES

 

Section 4.1.          Redemption for Tax Reasons.

 

If as a result of any Change of Law (as defined below):

 

(1)          the Issuer or a Guarantor is or would be required on the next succeeding interest payment date to pay any Additional Amounts; or

 

(2)          the issuers/borrowers of certain intercompany debt are or would be required on the next succeeding Interest Payment Date to pay Brazilian withholding taxes in excess of a general rate of 15%, or 25% in case of amounts paid to residents of countries which do not impose any income tax or which impose it at a maximum rate lower than 20% (or 17% if the relevant jurisdiction is committed to adopt international standards on tax transparency) or where the laws of that country or location impose restrictions on the disclosure of (x) shareholding composition; (y) the ownership of the investment; or (z) the beneficial ownership of income paid to non-resident persons, pursuant to Law No. 9,779, dated January 19, 1999; provided that, such requirement to pay such taxes in excess of such rate was not caused by, or otherwise the result of, whether directly or indirectly, wholly or in part, any amendment to the intercompany debt,

 

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and in any such case the payment of such excess amounts cannot be avoided by the use of any reasonable measures available to the Issuer or a Guarantor, the Notes may be repurchased, by the Issuer at the option of the Issuer or a Guarantor, in whole but not in part, upon not less than 30 nor more than 90 days’ notice to the Holders, which notice will be published, at any time following such Change of Law at a repurchase price equal to the principal amount thereof, plus accrued and unpaid interest, if any, to the date fixed for repurchase. The Issuer or a Guarantor will also pay to the Holders on the repurchase date any Additional Amounts which are payable. Following such repurchase, the Notes will be cancelled, or remain Outstanding, at the Issuer’s or a Guarantor’s election.

 

Change of Law” means any change in or amendment to the laws or regulations of Luxembourg, Brazil or Peru (or of any political subdivision thereof or therein) or the adoption, amendment or modification of any resolution of the Central Bank of Luxembourg, the Central Bank of Brazil or the Central Reserve Bank of Peru (or any successor authority thereto) which becomes effective on or after the date of this Indenture (or with respect to a successor, on or after the date such successor assumes the obligations under the Notes), resulting in the Issuer or a Guarantor on a consolidated basis being required to pay amounts with respect to Taxes above in a total aggregate amount in excess of that payable immediately prior to such change or amendment.

 

Prior to the delivery of any notice of repurchase in accordance with the foregoing, the Issuer or a Guarantor shall deliver to the Trustee and the Principal Paying Agent an Officer’s Certificate stating that the Issuer or a Guarantor, as the case may be, is entitled to effect such repurchase based on an Opinion of Counsel or written advice of a qualified tax expert, that the Issuer or a Guarantor has or will, or there is a substantial probability that the Issuer or a Guarantor has or will, become obligated to pay such excess amounts with respect to Taxes as a result of such Change of Law. Such notice, once delivered by the Issuer or a Guarantor to the Trustee, will be irrevocable.

 

If the Issuer or a Guarantor becomes subject at any time to any taxing jurisdiction other than Luxembourg, Brazil or Peru, references herein to Luxembourg, Brazil or Peru, as applicable, shall be construed to include such other jurisdiction.

 

Section 4.2.          Optional Redemption.

 

At any time before October 18, 2027 (which is the date that is three months prior to maturity of the notes (the “Par Call Date”)), the Issuer or a Guarantor has the right to redeem the Notes, in whole or in part and from time to time, at a redemption price equal to the greater of (1) 100% of the principal amount of the Notes being redeemed and (2) the sum of the present values of the remaining scheduled payments of principal and interest on the Notes being redeemed that would be due if the Notes matured on the Par Call Date (inclusive of interest accrued to the redemption date), discounted to the Redemption Date on a semi-annual basis (assuming a 360-day year consisting of twelve 30-day months) at the Treasury Rate plus 50 basis points, the case of clause (1) only, accrued and unpaid interest on the principal amount of the Notes being redeemed to, but excluding, such Redemption Date.

 

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At any time on or after the Par Call Date, the Issuer or a Guarantor has the right to redeem the Notes, in whole or in part and from time to time, at a redemption price equal to 100% of the principal amount of the Notes being redeemed plus accrued and unpaid interest on the principal amount of the Notes being redeemed to, but excluding, such Redemption Date.

 

The Issuer, any Guarantor or any of their respective Affiliates may at any time repurchase the Notes at any price in the open market or otherwise. The Issuer, any Guarantor or any of their respective Affiliates may hold or resell the Notes it purchases or may surrender them to the Trustee or an Agent for cancellation.

 

Section 4.3.          Applicability of Article.

 

Redemption of Notes at the election of the Issuer, as permitted or required by any provision of this Indenture, shall be made in accordance with such provision and this Article.

 

Section 4.4.          Election to Redeem; Notice to Trustee, Registrar and Paying Agent.

 

In the case of any redemption of Notes prior to the expiration of any restriction on such redemption provided in the terms of such Notes or elsewhere in this Indenture, the Issuer shall furnish the Trustee with an Officer’s Certificate evidencing compliance with such restriction.

 

The Issuer shall provide notice of redemption to the Trustee, Registrar and Paying Agents at least 15 days (or such shorter period as agreed to by the Trustee) prior to when such notice of redemption shall be provided to the Holders.

 

Section 4.5.          Notice of Redemption.

 

Notice of redemption pursuant to Section 4.1 and 4.2 hereof shall be given in the manner provided for in Section 1.6 hereof. The Trustee, Registrar and Paying Agent will notify the Holders at such Holder’s address appearing in the Note register at least 30 but not more than 60 days prior to the Redemption Date. A notice of any redemption may, at the Issuer’s or a Guarantor’s discretion, be subject to one or more conditions precedent.

 

All notices of redemption shall state:

 

(1)          the Redemption Date;

 

(2)          the Redemption Price;

 

(3)          that on the Redemption Date, the Redemption Price will become due and payable upon each such Note to be redeemed and that interest thereon will cease to accrue on and after said date;

 

(4)          the place or places where such Notes are to be surrendered for payment of the Redemption Price;

 

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(5)          the aggregate principal amount of Notes being redeemed;

 

(6)          the CUSIP number or numbers of the Notes being redeemed;

 

(7)          if fewer than all the outstanding Notes are to be redeemed, or if a Note is to be redeemed in part only, the identification and principal amounts at maturity of the particular Notes (or portion thereof) to be redeemed; and

 

(8)          that no representation is made as to the correctness or accuracy of the CUSIP numbers, if any, listed in such notice or printed on the Notes.

 

Section 4.6.          Deposit of Redemption Price.

 

By 11:00 a.m. (New York City time) on the Business Day prior to any Redemption Date, the Issuer or a Guarantor shall deposit with the Principal Paying Agent (or, if the Issuer is acting as its own Paying Agent, segregate and hold in trust as provided in Section 11.3) an amount of money sufficient to pay the Redemption Price on all of the Notes which are to be repurchased on that date. In the case of a partial redemption of Notes that are represented by a Global Note, the relevant Notes will be redeemed in accordance with the rules of DTC.

 

Section 4.7.          Notes Payable on Redemption Date.

 

Notice of redemption having been given as aforesaid, the Notes so to be redeemed shall, on the Redemption Date, become due and payable at the Redemption Price therein specified, and from and after such date (unless the Issuer shall default in the payment of the Redemption Price and accrued and unpaid interest) such Notes shall cease to bear interest. Upon surrender of any such Note for redemption in accordance with said notice, such Note shall be paid by the Issuer at the Redemption Price, together with accrued and unpaid interest to the Redemption Date; provided, however, that installments of interest whose Maturity Date is on or prior to the Redemption Date shall be payable to the Holders of such Notes, or one or more Predecessor Notes, registered as such at the close of business on the relevant Record Dates according to their terms and the provisions of Section 3.7.

 

If any Note called for redemption shall not be so paid upon surrender thereof for redemption, the principal (and premium, if any) shall, until paid, bear interest from the Redemption Date at the rate provided by the Note.

 

Article V

 

SATISFACTION AND DISCHARGE

 

Section 5.1.          Satisfaction and Discharge of Indenture.

 

This Indenture shall cease to be of further effect as to all Outstanding Notes, and the Trustee, on demand of and at the expense of the Issuer, shall execute proper instruments acknowledging satisfaction and discharge of this Indenture, when

 

(1)         (A)       all Outstanding Notes (except lost, stolen or destroyed Notes which have been replaced or paid) have been delivered to the Trustee for cancellation; or

 

              (B)       all Outstanding Notes that have not been delivered to the Trustee for cancellation (i) have become due and payable, (ii) will become due and payable at their Stated Maturity within one year, or (iii) are to be called for redemption within one year under arrangements satisfactory to the Trustee for the giving of notice of a redemption by the Issuer or a Guarantor; and, in each case, the Issuer or a Guarantor irrevocably deposits or causes to be deposited with the Trustee or its designee as funds in trust solely for the benefit of the Holders, cash, Cash Equivalents or U.S. Government Obligations in an amount as will be sufficient without consideration of any reinvestment of interest, to pay and discharge all principal, premium and Additional Amounts, if any, and accrued and unpaid interest to the date of maturity or redemption on the Notes not delivered to the Trustee for cancellation and delivers irrevocable instructions to the Trustee to apply the deposited money toward the payment of the Notes at maturity or the redemption date, as the case may be;

 

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(2)          the Issuer or a Guarantor has paid or caused to be paid all other sums payable hereunder;

 

(3)          the Issuer or a Guarantor has delivered to the Trustee an Officer’s Certificate and an Opinion of Counsel, each stating that all conditions precedent herein provided for relating to the satisfaction and discharge of this Indenture have been complied with; and

 

(4)          the Trustee shall have received such other documents and assurances as the Trustee shall have reasonably requested.

 

Notwithstanding the satisfaction and discharge of this Indenture, (i) the obligations of the Issuer to the Trustee under Section 7.7 hereof, (ii) substitution of apparently mutilated, defaced, destroyed, lost or stolen Notes, (iii) rights of Holders of Notes to receive payment of principal of and premium, if any, and interest (including Additional Amounts, if any) on the Notes, (iv) rights, obligations and immunities of the Trustee under this Indenture (including, if money shall have been deposited with the Trustee pursuant to subclause (B) of clause (1) of this Section, the obligations of the Trustee under Section 5.2 hereof and the last paragraph of Section 11.3 hereof), and (v) rights of Holders of the Notes as beneficiaries of this Indenture with respect to any property deposited with the Trustee payable to all or any of them, shall survive.

 

Section 5.2.          Application of Trust Money.

 

Subject to the provisions of the last paragraph of Section 11.3, all money deposited with the Trustee pursuant to Section 5.1 hereof shall be held in trust and applied by it, in accordance with the provisions of the Notes and this Indenture, to the payment, either directly or through any Paying Agent (including the Issuer or a Guarantor acting as its own Paying Agent) as the Trustee may determine, to the Persons entitled thereto, of the principal (and premium, if any) and interest for whose payment such money has been deposited with the Trustee.

 

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Article VI

 


REMEDIES

 

Section 6.1.          Events of Default.

 

Event of Default,” wherever used herein, means any one of the following events (whatever the reason for such Event of Default and whether it shall be voluntary or involuntary or be effected by operation of law or pursuant to any judgment, decree or order of any court or any order, rule or regulation of any administrative or governmental body):

 

(1)          failure to pay any amount of principal of (or premium, if any) any Note when due;

 

(2)          failure to pay any interest, including Additional Amounts, if any, on any Note when due and such failure shall continue for a period of 30 days;

 

(3)          failure to perform any covenant or agreement of the Issuer or any Guarantor under this Indenture or the Notes and such failure remains unremedied for 60 days after the Trustee has given written notice thereof to the Issuer or any Guarantor;

 

(4)          failure to pay when due or, as the case may be, within any originally applicable grace period, any amount of principal and premium, if any, or interest (including Additional Amounts, if any), due under the terms of any instrument evidencing Indebtedness of the Issuer or any of its Designated Subsidiaries, or any such Indebtedness of the Issuer or any of its Designated Subsidiaries that becomes due and payable prior to its stated maturity otherwise than at the option of the issuer thereof by reason of the occurrence of an event of default howsoever described; provided that the aggregate amount of any such Indebtedness equals with respect to such Person, on a consolidated basis U.S.$100.0 million or more (or its equivalent in other currency or currencies);

 

(5)          the rendering of a final judgment or judgments (not subject to appeal) for the payment of money against the Issuer or any of its Designated Subsidiaries which remains undischarged, unbonded or unstayed (and otherwise not covered by enforceable insurance policies issued by reputable and creditworthy insurance companies) for a period of 60 consecutive days after the date on which the right to appeal all such judgments has expired or, if later, the date therein specified for payment; provided that the aggregate amount of any such final judgment equals or exceeds with respect to such Person, on a consolidated basis U.S.$100.0 million (or its equivalent in other currency or currencies);

 

(6)          all or substantially all of the assets of the Issuer (on a consolidated basis) shall be condemned, seized or otherwise appropriated, or custody of such property shall be assumed by any governmental authority or court or other person purporting to act under the authority of the federal government of any jurisdiction, or the Issuer shall be prevented from exercising normal control over all or substantially all of its property or revenues (on a consolidated basis), if the whole or part of such property or revenues is material to the Issuer (on a consolidated basis);

 

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(7)          (a) a secured party takes possession of all or substantially all the assets or revenues of the Issuer (on a consolidated basis) or (b) a receiver or similar officer is appointed, of all or substantially all the assets or revenues of the Issuer (on a consolidated basis);

 

(8)          the Issuer or any Guarantor pursuant to or under or within the meaning of any Bankruptcy Law (a) commences a voluntary case or proceeding; (b) consents to the making of a Bankruptcy Order in an involuntary case or proceeding or the commencement of any case against it; (c) consents to the appointment of a custodian of it or for substantially all its property; (d) makes a general assignment for the benefit of its creditors; (e) files an answer or consent seeking reorganization or relief; (f) shall admit in writing its inability to pay its debts generally; or (g) consents to the filing of a petition in bankruptcy;

 

(9)          a court of competent jurisdiction in any involuntary case or proceeding enters a Bankruptcy Order against the Issuer or any Guarantor, and such Bankruptcy Order remains unstayed and in effect for 60 consecutive days; and

 

(10)        any of the Guarantees is not (or is claimed by any Guarantor not to be) in full force and effect.

 

If any Event of Default (other than an Event of Default described in clause (8) with respect to the Issuer or Nexa Peru) shall occur and be continuing, either (i) the Trustee or (ii) the Holders, with written notice to the Trustee, of at least 25% in aggregate principal amount of the Outstanding Notes may accelerate the maturity of all Notes; provided that, after such acceleration, but before a judgment or decree based on acceleration, the Holders of a majority in aggregate principal amount of Outstanding Notes may, as provided in Section 6.12, rescind and annul such acceleration if all Events of Default, other than the nonpayment of accelerated principal, have been cured or waived as provided in this Indenture. The Trustee shall not be deemed to have notice of any Default or Event of Default (other than a payment default) unless a Responsible Officer of the Trustee has actual knowledge thereof or unless written notice of any event which is in fact such a default is received by a Responsible Officer of the Trustee at the Corporate Trust Office of the Trustee, and such notice references the Notes and this Indenture. If an Event of Default specified in clause (8) above occurs with respect to the Issuer or Nexa Peru, the Outstanding Notes will ipso facto become immediately due and payable without any declaration or other act on the part of the Trustee or any Holder.

 

Section 6.2.          Collection of Indebtedness and Suits for Enforcement by Trustee. The Issuer and the Guarantors covenant that if

 

(1)          default is made in the payment of any interest on any Note, (including Additional Amounts, if any), when such amounts become due and payable and such default continues for a period of 30 days; or

 

(2)          default is made in the payment of the principal of (or premium, if any, on) any Note at the Maturity thereof or, with respect to any Note to be redeemed, at the Redemption Date thereof,

 

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the Issuer and the Guarantors (subject to the limitations provided in this Indenture) will, jointly and severally, upon demand of the Trustee, pay to it, for the benefit of the Holders of such Notes, the whole amount then due and payable on such Notes for principal (and premium, if any) and interest (including Additional Amounts, if any), and, to the extent that payment of interest on overdue amounts shall be legally enforceable, interest on any overdue principal (and premium, if any) and on any overdue interest, at the rate provided by the Notes, and, in addition thereto, such further amount as shall be sufficient to cover the costs and expenses incurred by the Trustee under this Indenture, including the reasonable compensation, expenses, disbursements and advances of the Trustee, its agents and counsel.

 

If the Issuer and the Guarantors fail to pay such amounts forthwith upon such demand, the Trustee, in its own name and as trustee of an express trust, may institute a judicial proceeding for the collection of the sums so due and unpaid, may prosecute such proceeding to judgment or final decree, and may enforce the same against the Issuer, the Guarantors or any other obligor upon the Notes and collect the moneys adjudged or decreed to be payable in the manner provided by law out of the property of the Issuer, the Guarantors or any other obligor upon the Notes, wherever situated.

 

If an Event of Default occurs and is continuing, the Trustee may in its discretion proceed to protect and enforce its rights and the rights under this Indenture of the Holders by such appropriate judicial proceedings as the Trustee shall deem most effective to protect and enforce any such rights, whether for the specific enforcement of any covenant or agreement in this Indenture or in aid of the exercise of any power granted herein including, without limitation, seeking recourse against the Issuer or the Guarantors or proceeding to enforce any other proper remedy.

 

Section 6.3.          Trustee May File Proofs of Claim.

 

The Trustee may file such proofs of claim and other papers or documents as may be necessary or advisable in order to have the claims of the Trustee and the Holders allowed in any judicial proceedings relative to the Issuer, the Guarantors, their respective creditors or its property and, unless prohibited by law or applicable regulations, may vote on behalf of the Holders at their direction in any election of a trustee in bankruptcy or other Person performing similar functions, and any custodian in any such judicial proceeding is hereby authorized by each Holder to make payments to the Trustee and, in the event that the Trustee shall consent to the making of such payments directly to the Holders, to pay to the Trustee any amount due it for the reasonable compensation, expenses, disbursements and advances of the Trustee, its agents and its counsel, and any other amounts due the Trustee under Section 7.7.

 

Section 6.4.          Trustee May Enforce Claims Without Possession of Notes.

 

All rights of action and claims under this Indenture or the Notes may be prosecuted and enforced by the Trustee without the possession of any of the Notes or the production thereof in any proceeding relating thereto, and any such proceeding instituted by the Trustee shall be brought in its own name as trustee of an express trust, and any recovery of judgment shall, after provision for the payment of the reasonable compensation, expenses, disbursements and advances of the Trustee, its agents and counsel, be for the ratable benefit of the Holders of the Notes in respect of which such judgment has been recovered.

 

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Section 6.5.          Application of Money Collected.

 

Any money collected by the Trustee pursuant to this Article shall be applied in the following order, at the date or dates fixed by the Trustee and, in case of the distribution of such money on account of principal (or premium, if any) or interest, upon presentation of the Notes and the notation thereon of the payment if only partially paid and upon surrender thereof if fully paid;

 

FIRST: To the payment of all amounts due to the Trustee and the Agents under this Indenture; and

 

SECOND: To the payment of the amounts then due and unpaid for principal of (and premium, if any) and interest on the Notes in respect of which or for the benefit of which such money has been collected, ratably, without preference or priority of any kind, according to the amounts due and payable on such Notes for principal (and premium, if any) and interest, respectively.

 

The Trustee, upon prior written notice to the Issuer, may fix a record date and payment date for any payment to the Holders pursuant to this Section 6.5.

 

Section 6.6.          Limitation on Suits.

 

No Holder of any Note shall have any right to institute any proceeding, judicial or otherwise, with respect to this Indenture, or for the appointment of a receiver or trustee, or for any other remedy hereunder, unless:

 

(1)          such Holder shall have previously given written notice to the Trustee of a continuing Event of Default;

 

(2)          the Holders of at least 25% in aggregate principal amount of the Outstanding Notes shall have made written request to the Trustee to institute proceedings in respect of such Event of Default in its own name as Trustee hereunder and shall have offered to the Trustee indemnity and/or security reasonably satisfactory to the Trustee against the costs, expenses and liabilities to be incurred in compliance with such request;

 

(3)          the Trustee for 60 days after its receipt of such notice, request and offer shall have failed to institute any such proceeding; and

 

(4)          no direction inconsistent with such written request shall have been given to the Trustee during such 60-day period by the Holders of a majority in principal amount of the Outstanding Notes;

 

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it being understood and intended that no one or more Holders shall have any right in any manner whatever by virtue of, or by availing of, any provision of this Indenture or any Note or the Guarantees to affect, disturb or prejudice the rights of any other Holders, or to obtain or to seek to obtain priority or preference over any other Holders or to enforce any right under this Indenture (it being understood that the Trustee does not have an affirmative duty to ascertain whether or not such actions or forbearances are unduly prejudicial to such Holders), any Note or the Guarantees, except in the manner herein provided and for the equal and ratable benefit of all the Holders.

 

Section 6.7.          Unconditional Right of Holders to Receive Principal, Premium and Interest.

 

Notwithstanding any other provision in this Indenture, the Notes or the Guarantees, the Holder of any Note shall have the right, which is absolute and unconditional, to receive payment of the principal of (and premium, if any) and (subject to Section 3.6) interest on such Note on the respective Stated Maturities expressed in such Note (or earlier Redemption Date) and to institute suit for the enforcement of any such payment, and such rights shall not be impaired without the consent of such Holder.

 

Section 6.8.          Restoration of Rights and Remedies.

 

If the Trustee or any Holder has instituted any proceeding to enforce any right or remedy under this Indenture, any Note or the Guarantees, and such proceeding has been discontinued or abandoned for any reason, or has been determined adversely to the Trustee or to such Holder, then and in every such case, subject to any determination in such proceeding, the Issuer, the Guarantor, the Trustee and the Holders shall be restored severally and respectively to their former positions hereunder and thereafter all rights and remedies of the Trustee and the Holders shall continue as though no such proceeding had been instituted.

 

Section 6.9.          Rights and Remedies Cumulative.

 

Except as otherwise provided with respect to the replacement or payment of mutilated, destroyed, lost or stolen Notes in the last paragraph of Section 3.5 hereof, no right or remedy herein conferred upon or reserved to the Trustee or to the Holders is intended to be exclusive of any other right or remedy, and every right and remedy shall, to the extent permitted by law, be cumulative and in addition to every other right and remedy given hereunder or now or hereafter existing at law or in equity or otherwise. The assertion or employment of any right or remedy hereunder, or otherwise, shall not prevent the concurrent assertion or employment of any other appropriate right or remedy.

 

Section 6.10.        Delay or Omission Not Waiver.

 

No delay or omission of the Trustee or of any Holder of any Note to exercise any right or remedy accruing upon any Event of Default shall impair any such right or remedy or constitute a waiver of any such Event of Default or an acquiescence therein. Every right and remedy given by this Article or by law to the Trustee or to the Holders may be exercised from time to time, and as often as may be deemed expedient, by the Trustee or by the Holders, as the case may be.

 

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Section 6.11.        Control by Holders.

 

The Holders of a majority of the aggregate principal amount of the Outstanding Notes shall have the right to direct the time, method and place of conducting any proceeding for any remedy available to the Trustee or exercising any trust or power conferred on the Trustee, provided that:

 

(1)          such direction shall not be in conflict with any rule of law or with this Indenture or expose the Trustee to personal liability (as determined in the sole discretion of the Trustee); and

 

(2)          the Trustee may take any other action deemed proper by the Trustee which is not inconsistent with such direction.

 

The Trustee may refuse, however, to follow any direction that the Trustee, in its sole discretion, determines may be unduly prejudicial to the rights of the Holders or that may subject the Trustee to any liability, loss or expense if the Trustee determines, in its sole discretion, that it lacks satisfactory indemnification and/or security against such liability, loss or expense.

 

Section 6.12.        Waiver of Past Defaults.

 

The Holders of not less than a majority in aggregate principal amount of the Outstanding Notes may by written notice to the Issuer and the Trustee waive any past default hereunder and rescind and annul any declaration of acceleration and its consequences, except a default:

 

(1)          in the payment of the principal of (or premium, if any) or interest on any Note; or

 

(2)          in respect of a covenant or provision hereof which under Article X cannot be modified or amended without the consent of the Holder of each Outstanding Note affected.

 

Upon any such waiver, such default shall cease to exist, and any Event of Default arising therefrom shall be deemed to have been cured, for every purpose of this Indenture; but no such waiver shall extend to any subsequent or other default or impair any right consequent thereon.

 

Section 6.13.        Undertaking for Costs.

 

In any suit for the enforcement of any right or remedy under this Indenture or in any suit against the Trustee for any action taken or omitted by it as a Trustee, a court in its discretion may require the filing by any party litigant in the suit of an undertaking to pay the costs of the suit, and the court in its discretion may assess reasonable costs, including reasonable attorney’s fees and expenses, against any party litigant in the suit, having due regard to the merits and good faith of the claims or defenses made by the party litigant. This Section 6.13 does not apply to a suit by the Trustee, a suit by a Holder pursuant to Section 6.7 hereof, or a suit by Holders of more than 10% in principal amount of the then Outstanding Notes.

 

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Article VII

 

THE TRUSTEE

 

Section 7.1.          Certain Duties and Responsibilities.

 

(a)               Except during the continuance of an Event of Default,

 

(1)               the Trustee undertakes to perform solely such duties and only such duties as are specifically set forth in this Indenture, and Trustee shall not be liable except for the performance of such duties; and no implied covenants or obligations shall be read into this Indenture against the Trustee; and

 

(2)               in the absence of gross negligence on its part, the Trustee may conclusively rely, as to the truth of the statements and the correctness of the opinions expressed therein, upon certificates or opinions furnished to the Trustee and conforming to the requirements of this Indenture; but in the case of any such certificates or opinions which by any provision hereof are specifically required to be furnished to the Trustee, the Trustee shall be under a duty to examine the same to determine whether or not they conform to the form requirements of this Indenture (but need not confirm or investigate the accuracy of mathematical calculations or other facts stated therein).

 

(b)               In case an Event of Default has occurred and is continuing, the Trustee shall exercise such of the rights and powers vested in it by this Indenture, and use the same degree of care and skill in their exercise, as a prudent person would exercise or use under the circumstances in the conduct of such person’s own affairs.

 

(c)               No provision of this Indenture shall be construed to relieve the Trustee from liability for its own grossly negligent action or its own willful misconduct, except that:

 

(1)               this Subsection shall not be construed to limit the effect of Subsection (a) of this Section;

 

(2)               the Trustee shall not be liable for any error of judgment made in good faith by a Responsible Officer or Officers of the Trustee, unless it shall be proved that the Trustee was grossly negligent in ascertaining the pertinent facts;

 

(3)               the Trustee shall not be liable with respect to any action taken or omitted to be taken by it in good faith in accordance with the direction of the Holders of a majority in principal amount of the Outstanding Note of any series, determined as provided in Section 6.2, relating to the time, method and place of conducting any proceeding for any remedy available to the Trustee, or exercising any trust or power conferred upon the Trustee, under this Indenture with respect to the Note;

 

(4)               no provision of this Indenture shall require the Trustee to expend or risk its own funds or otherwise incur any financial liability in the performance of any of its duties hereunder, or in the exercise of any of its rights or powers, if it shall have reasonable grounds for believing that repayment of such funds or adequate indemnity and/or security against such risk or liability is not reasonably assured to it;

 

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(5)               the Trustee shall not be liable in respect of any payment (as to the correctness of amount, entitlement to receive or any other matters relating to payment) or notice effected by the Issuer or any Paying Agent or any records maintained by any co-Note Registrar with respect to the Notes;

 

(6)               if any party fails to deliver a notice relating to an event the fact of which, pursuant to this Indenture, requires notice to be sent to the Trustee, the Trustee may conclusively rely on its failure to receive such notice as reason to act as if no such event occurred, unless a Responsible Officer of the Trustee had actual knowledge of such event;

 

(7)               the delivery of any information to the Trustee under this Indenture, including but not limited to any Rule 144A information, or reports to the Trustee is for informational purposes only and the receipt of such information or reports by the Trustee shall not constitute constructive notice of any information contained therein;

 

(8)               in the absence of written investment direction from the Issuer, all cash received by the Trustee shall be placed in a non-interest bearing trust account, and in no event shall the Trustee be liable for the selection of investments or for investment losses incurred thereon or for losses incurred as a result of the liquidation of any such investment prior to its maturity date or the failure of the party directing such investments prior to its maturity date or the failure of the party directing such investment to provide timely written investment direction, and the Trustee shall have no obligation to invest or reinvest any amounts held hereunder in the absence of such written investment direction from the Issuer;

 

(9)               in the event that the Trustee is also acting as custodian, Registrar, Paying Agent, exchange agent, bid solicitation agent or transfer agent hereunder, the rights and protections afforded to the Trustee pursuant to this Article VII shall also be afforded to such custodian, Registrar, Paying Agent, exchange agent, bid solicitation agent or transfer agent;

 

(10)            any application by the Trustee for written instructions from the Issuer (other than with regard to any action proposed to be taken or omitted to be taken by the Trustee that affects the rights of the Holders of the Notes under this Indenture) may, at the option of the Trustee, set forth in writing any action proposed to be taken or omitted by the Trustee under this Indenture and the date on and/or after which such action shall be taken or such omission shall be effective. The Trustee shall not be liable to the Issuer for any action taken by, or omission of, the Trustee in accordance with a proposal included in such application on or after the date specified in such application (which date shall not be less than three Business Days after the date any officer that the Issuer has indicated to the Trustee should receive such application actually receives such application, unless any such officer shall have consented in writing to any earlier date), unless, prior to taking any such action (or the effective date in the case of any omission), the Trustee shall have received written instructions in accordance with this Indenture in response to such application specifying the action to be taken or omitted.

 

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(d)               Whether or not therein expressly so provided, every provision of this Indenture relating to the conduct or affecting the liability of or affording protection to the Trustee shall be subject to the provisions of this Section.

 

Section 7.2.          Notice of Defaults.

 

The Trustee shall give the Holders notice of any Default (“Notice of Default”) that has occurred and is continuing and of which a Responsible Officer of the Trustee has actual knowledge, within 90 days after the occurrence of such Default (but not less than 15 days after knowledge thereof). The Trustee may withhold from Holders notice of any continuing Default or Event of Default (except a Default or Event of Default relating to the payment of principal, premium, if any, or interest on, the Notes) if it determines that withholding such notice is in their interest; provided that, in the case of a default of a character specified in Section 6.1(4), no such notice to Holders shall be given until at least 30 days after the occurrence thereof.

 

Section 7.3.          Certain Rights of Trustee and the Agents.

 

Subject to the provisions of Section 7.1:

 

(a)               the Trustee and the Agents may rely conclusively and shall be protected in acting or refraining from acting upon any resolution, certificate, statement, instrument, opinion, report, notice, request, direction, consent, order, bond, debenture, note, other evidence of indebtedness or other paper or document believed by it to be genuine and to have been signed or presented by the proper party or parties;

 

(b)               any request or direction of the Issuer mentioned herein shall be sufficiently evidenced by an Issuer Request or an Issuer Order and any resolution of the Board of Directors of the Issuer may be sufficiently evidenced by a Board Resolution;

 

(c)               whenever in the administration of this Indenture the Trustee or an Agent shall deem it desirable that a matter be proved or established prior to taking, suffering or omitting any action hereunder, the Trustee or such Agent, as the case may be, (unless other evidence be herein specifically prescribed) may, in the absence of gross negligence on its part, rely upon an Officer’s Certificate or an Opinion of Counsel;

 

(d)               the Trustee or the Agents may consult with counsel of its selection, at the expense of the Issuer, and the advice of such counsel or any Opinion of Counsel shall be full and complete authorization and protection in respect of any action taken, suffered or omitted by it hereunder in good faith and in reliance thereon;

 

(e)               the Trustee and each Agent shall be under no obligation to exercise any of the rights or powers vested in it by this Indenture at the request or direction of any of the Holders pursuant to this Indenture, unless such Holders shall have offered to the Trustee or such Agent, as applicable, security and/or indemnity satisfactory to it against the costs, expenses and liabilities which might be incurred by it in compliance with such request or direction satisfactory to the Trustee or such Agent, as applicable;

 

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(f)                neither the Trustee nor any Agent shall be bound to make any investigation into the facts or matters stated in any resolution, certificate, statement, instrument, report, opinion, notice, request, direction, consent, order, bond, debenture, note, other evidence of indebtedness or other paper or document, but the Trustee and each Agent, in its discretion, may make such further inquiry or investigation into such facts or matters as it may see fit, and, if the Trustee or an Agent shall determine to make such further inquiry or investigation, it shall be entitled to examine the books, records and premises of the Issuer and the Guarantor, personally or by agent or attorney at the sole cost of the Issuer and shall incur no liability or additional liability of any kind by reason of such inquiry or investigation;

 

(g)               the Trustee and each Agent may execute any of the trusts or powers hereunder or perform any duties hereunder either directly or by or through agents or attorneys and the Trustee and each Agent shall not be responsible for any misconduct or negligence on the part, or for the supervision of, any agent or attorney appointed with due care by it hereunder;

 

(h)               neither the Trustee nor any Agent shall be liable for any action taken, suffered or omitted by it in good faith which the Trustee or such Agent, as applicable, believed to have been authorized or within its rights or powers;

 

(i)                 neither the Trustee nor any Agent shall be charged with knowledge of any default or Event of Default with respect to the Notes, unless either (1) a Responsible Officer shall have actual knowledge of such default or Event of Default, or (2) written notice of such default or Event of Default shall have been received by a Responsible Officer of the Trustee by the Issuer, the Guarantor or by any Holder of the Notes;

 

(j)                 in no event shall the Trustee or any Agent be responsible or liable for special, indirect, punitive or consequential loss or damage of any kind whatsoever (including, but not limited to, loss of profit) irrespective of whether the Trustee or such Agent has been advised of the likelihood of such loss or damage and regardless of the form of action;

 

(k)               the rights, privileges, protections, immunities and benefits given to the Trustee and the Agents, including, without limitation, its right to be indemnified, are extended to, and shall be enforceable by, the Trustee and the Agents in each of their capacities hereunder, and each agent, custodian and other Person employed to act hereunder;

 

(l)                neither the Trustee nor the Agents shall be required to give any bond or surety in respect of the performance of its powers and duties hereunder;

 

(m)              the Trustee and the Agents may request that the Issuer deliver a certificate setting forth the names of individuals and/or titles of officers authorized at such time to take specified actions pursuant to this Indenture; and

 

(n)               the permissive rights of the Trustee enumerated herein shall not be construed as duties.

 

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Section 7.4.          Not Responsible for Recitals or Issuance of Notes.

 

The recitals contained herein, in the Notes and in the Guarantees endorsed thereon, except the Trustee’s certificates of authentication, shall be taken as the statements of the Issuer or the Guarantors, as the case may be, and the Trustee assumes no responsibility for their correctness. The Trustee makes no representations as to the validity or sufficiency of this Indenture or the Notes. The Trustee shall not be accountable for the use or application by the Issuer of Notes or the proceeds thereof.

 

Section 7.5.          May Hold Notes.

 

The Trustee, any Paying Agent or Transfer Agent, any Registrar (if other than the Trustee) or any other agent of the Issuer or the Guarantors, in its individual or any other capacity, may become the owner or pledgee of Notes and, subject to Section 7.8 and 7.12, may otherwise deal with the Issuer and the Guarantors with the same rights it would have if it were not Trustee, Paying Agent, Transfer Agent, Registrar or such other agent.

 

Section 7.6.          Money Held in Trust.

 

All moneys received by the Trustee or any Paying Agent shall, until used or applied as herein provided, be held in trust for the purposes for which they were received, and need not be segregated from other funds of the Trustee or Paying Agent, except as otherwise required by law. Neither the Trustee nor any Paying Agent shall be under any liability for interest on any moneys received by it hereunder except such as it may agree in writing with the Issuer to pay thereon.

 

Section 7.7.          Compensation and Reimbursement.

 

The Issuer and the Guarantors agree:

 

(1)               to, jointly and severally, pay to the Trustee and the Agents from time to time upon demand such compensation for all services rendered by it hereunder as shall be agreed upon in writing (which compensation shall not be limited by any provision of law in regard to the compensation of a trustee of an express trust), as such fees may be adjusted from time to time;

 

(2)               except as otherwise expressly provided herein, to, jointly and severally, reimburse each of the Trustee and the Agents upon its request for all reasonable expenses and disbursements incurred or made by it in accordance with any provision of this Indenture (including the reasonable compensation and the expenses and disbursements of their agents and counsel), except any such expense, disbursement or advance as may be attributable to its gross negligence or willful misconduct; and

 

(3)               to, jointly and severally, indemnify each the Trustee and the Agents for, and to hold each harmless against, any loss, liability, cost, damage, claim or expense (including taxes and the reasonable compensation, expenses and disbursements of its agents, accountants, experts and counsel) incurred without gross negligence or willful misconduct on its part as determined in a final judgment of a court with competent jurisdiction, arising out of or in connection with the acceptance or administration of this trust or the performance by it of its duties and obligations or the exercise of its rights hereunder, including the costs and expenses of enforcing this Indenture against the Issuer or the Guarantors, as the case may be (including, without limitation, this Section 7.7), and of defending against any claim (whether asserted by any Holder or the Issuer or the Guarantors or any other Person, as the case may be) or liability in connection with the exercise or performance of any of its powers or duties hereunder. The provisions of this Section 7.7 shall survive any termination of this Indenture and the resignation or removal of the Trustee, the Principal Paying Agent or other Paying Agent.

 

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As security for the performance of the obligations of the Issuer or the Guarantors, as the case may be, under this Section 7.7, the Trustee shall have a lien prior to the Notes upon all property and funds held or collected by the Trustee, except funds held in trust for the payment of principal of (and premium, if any) or interest on particular Notes. The Trustee’s right to receive payment of any amounts due under this Section 7.7 shall not be subordinate to any other liability or indebtedness of the Issuer or the Guarantors, as the case may be (even though the Notes may be so subordinated).

 

The obligation of the Issuer under this Section 7.7 shall survive the satisfaction and discharge of this Indenture and the earlier resignation or removal or the Trustee. The indemnification provided in this Section 7.7 shall extend to the officers, directors, agents and employees of the Trustee.

 

When the Trustee incurs expenses or renders services after an Event of Default specified in Section 6.1 occurs, the expenses and the compensation for such services are intended to constitute expenses of administration under Title 11, U.S. Code, or any similar Federal, State or analogous foreign law for the relief of debtors.

 

Section 7.8.          Corporate Trustee Required; Eligibility.

 

There shall at all times be a Trustee hereunder which shall be a Person that is eligible pursuant to the Trust Indenture Act to act as such and has a combined capital and surplus of at least U.S.$50,000,000 and its Corporate Trust Office in The City of New York, New York. If such Person publishes reports of condition at least annually, pursuant to law or to the requirements of a Federal, State, Territorial or District of Columbia supervising or examining authority, then for the purposes of this Section, the combined capital and surplus of such Person shall be deemed to be its combined capital and surplus as set forth in its most recent report of condition so published. If at any time the Trustee shall cease to be eligible in accordance with the provisions of this Section, it shall resign immediately in the manner and with the effect hereinafter specified in this Article.

 

Section 7.9.          Resignation and Removal; Appointment of Successor.

 

(a)               No resignation or removal of the Trustee and no appointment of a successor Trustee pursuant to this Article shall become effective until the acceptance of appointment by the successor Trustee under Section 7.10, at which time the retiring Trustee shall be fully discharged from its obligations hereunder.

 

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(b)               The Trustee and the Principal Paying Agent may resign at any time by giving written notice thereof to the Issuer. If an instrument of acceptance by a successor Trustee or Principal Paying Agent shall not have been delivered to the Trustee or Principal Paying Agent, as the case may be, within 30 days after the giving of such notice of resignation, the resigning Trustee or Principal Paying Agent may petition, at the expense of the Issuer, any court of competent jurisdiction for the appointment of a successor Trustee or Principal Paying Agent, as the case may be.

 

(c)               The Trustee may be removed at any time by Act of the Holders of a majority in principal amount of the Outstanding Notes, delivered to the Trustee and to the Issuer. If an instrument of acceptance by a successor Trustee shall not have been delivered to the Trustee within 30 days after the giving of such notice of removal, the Issuer may petition, at its expense, any court of competent jurisdiction for the appointment of a successor Trustee.

 

(d)               The Agents (other than the Principal Paying Agent) may resign at any time by giving written notice thereof to the Issuer. The Agents may appoint a successor Agent if the Issuer does not.

 

(e)               So long as no Event of Default has occurred and is continuing, the Issuer may remove the Trustee or any Agent and appoint a new Trustee or Agent, as applicable, provided that such Trustee meets the eligibility requirements of Section 7.8.

 

(f)                If at any time:

 

(1)               the Trustee shall fail to comply with Section 7.8 after written request therefore by the Issuer or by any Holder who has been a bona fide Holder of a Note for at least six months; or

 

(2)               the Trustee shall cease to be eligible under Section 7.8 and shall fail to resign after written request therefore by the Issuer or by any such Holder; or

 

(3)               the Trustee shall become incapable of acting or shall be adjudged a bankrupt or insolvent or a receiver of the Trustee or of its property shall be appointed or any public officer shall take charge or control of the Trustee or of its property or affairs for the purpose of rehabilitation, conservation or liquidation, then, in any such case, (i) the Issuer by a Board Resolution may remove the Trustee, or (ii) any Holder who has been a bona fide Holder of a Note for at least six months may, on behalf of himself or herself and all others similarly situated, petition any court of competent jurisdiction for the removal of the Trustee and the appointment of a successor Trustee.

 

(g)               If the Trustee shall resign, be removed or become incapable of acting, or if a vacancy shall occur in the office of Trustee for any cause, the Issuer, by a Board Resolution, shall promptly appoint a successor Trustee. If, within one year after such resignation, removal or incapability, or the occurrence of such vacancy, a successor Trustee shall be appointed by Act of the Holders of a majority in principal amount of the Outstanding Notes delivered to the Issuer and the retiring Trustee, the successor Trustee so appointed shall, forthwith upon its acceptance of such appointment, become the successor Trustee and supersede the successor Trustee appointed by the Issuer. If no successor Trustee shall have been so appointed by the Issuer or the Holders and accepted appointment in the manner hereinafter provided, any Holder who has been a bona fide Holder of a Note for at least six months may, on behalf of himself or herself and all others similarly situated, petition any court of competent jurisdiction at the expense of the Issuer for the appointment of a successor Trustee.

 

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(h)               The Issuer shall give notice of each resignation and each removal of the Trustee and each appointment of a successor Trustee to all Holders in the manner provided in Section 1.6. Each notice shall include the name of the successor Trustee and the address of its Corporate Trust Office at the expense of the Issuer.

 

Section 7.10.      Acceptance of Appointment by Successor.

 

Every successor Trustee appointed hereunder shall execute, acknowledge and deliver to the Issuer, the Guarantors and to the retiring Trustee an instrument accepting such appointment, and thereupon the resignation or removal of the retiring Trustee shall become effective and such successor Trustee, without any further act, deed or conveyance, shall become vested with all the rights, powers, trusts and duties of the retiring Trustee; but, on request of the Issuer or the successor Trustee, such retiring Trustee shall, upon payment of its charges, execute and deliver an instrument transferring to such successor Trustee all the rights, powers and trusts of the retiring Trustee and shall duly assign, transfer and deliver to such successor Trustee all property and money held by such retiring Trustee hereunder, subject nevertheless to its Lien, if any, provided for in Section 7.7. Upon request of any such successor Trustee, the Issuer and the Guarantors shall execute any and all instruments for more fully and certainty vesting in and confirming to such successor Trustee all such rights, powers and trusts. No successor Trustee shall accept its appointment unless at the time of such acceptance such successor Trustee shall be qualified and eligible under this Article.

 

Section 7.11.      Merger, Conversion, Consolidation or Succession to Business.

 

Any corporation or other entity into which the Trustee may be merged or convened or with which it may be consolidated, or any corporation or other entity resulting from any merger, conversion or consolidation to which the Trustee shall be a party, or any corporation or other entity succeeding to all or substantially all the corporate trust business of the Trustee, shall be the successor of the Trustee hereunder, provided that such corporation or other entity shall be otherwise qualified and eligible under this Article, without the execution or filing of any paper or any further act on the part of any of the parties hereto. In case any Notes shall have been authenticated, but not delivered, by the Trustee then in office, any successor by merger, conversion or consolidation to such authenticating Trustee may adopt such authentication and deliver the Notes so authenticated with the same effect as if such successor Trustee had itself authenticated such Notes.

 

Section 7.12.      Appointment of Authenticating Agent.

 

The Trustee may appoint an Authenticating Agent or Agents with respect to the Notes which shall be authorized to act on behalf of the Trustee to authenticate Notes issued upon original issue and upon exchange, registration of transfer or partial redemption thereof or pursuant to Section 3.5, and Notes so authenticated shall be entitled to the benefits of this Indenture and shall be valid and obligatory for all purposes as if authenticated by the Trustee hereunder. Wherever reference is made in this Indenture to the authentication and delivery of Notes by the Trustee or the Trustee’s certificate of authentication, such reference shall be deemed to include authentication and delivery on behalf of the Trustee by an Authenticating Agent and a certificate of authentication executed on behalf of the Trustee by an Authenticating Agent. Each Authenticating Agent shall be acceptable to the Issuer and shall at all times be a corporation organized and doing business under the laws of the United States, any State thereof or the District of Columbia, authorized under such laws to act as Authenticating Agent, having a combined capital and surplus of not less than U.S.$50,000,000 and subject to supervision or examination by Federal or State authority. If such Authenticating Agent publishes reports of condition at least annually, pursuant to law or to the requirements of said supervising or examining authority, then for the purposes of this Section, the combined capital and surplus of such Authenticating Agent shall be deemed to be its combined capital and surplus as set forth in its most recent report of condition so published. If at any time an Authenticating Agent shall cease to be eligible in accordance with the provisions of this Section, such Authenticating Agent shall resign immediately in the manner and with the effect specified in this Section.

 

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Any corporation or other entity into which an Authenticating Agent may be merged or converted or with which it may be consolidated, or any corporation or other entity resulting from any merger, conversion or consolidation to which such Authenticating Agent shall be a party, or any corporation or other entity succeeding to all or substantially all the corporate agency or corporate trust business of an Authenticating Agent, shall continue to be an Authenticating Agent, provided such corporation or other entity shall be otherwise eligible under this Section, without the execution or filing of any paper or any further act on the part of the Trustee or the Authenticating Agent.

 

An Authenticating Agent may resign at any time by giving written notice thereof to the Trustee and to the Issuer. The Trustee may at any time terminate the agency of an

 

Authenticating Agent by giving written notice thereof to such Authenticating Agent and to the Issuer. Upon receiving such a notice of resignation or upon such a termination, or in case at any time such Authenticating Agent shall cease to be eligible in accordance with the provisions of this Section, the Trustee may appoint a successor Authenticating Agent which shall be acceptable to the Issuer and shall give notice of such appointment in the manner provided in Section 1.6 to all Holders of Notes. Any successor Authenticating Agent upon acceptance of its appointment hereunder shall become vested with all the rights, powers and duties of its predecessor hereunder, with like effect as if originally named as an Authenticating Agent. No successor Authenticating Agent shall be appointed unless eligible under the provisions of this Section.

 

The Issuer agrees to pay to each Authenticating Agent from time to time reasonable compensation for its services under this Section.

 

If an appointment is made pursuant to this Section, the Notes may have endorsed thereon, in lieu of the Trustee’s certificate of authentication, an alternative certificate of authentication in the following form:

 

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“This is one of the Notes referred to in the within-mentioned Indenture.

 

  THE BANK OF NEW YORK MELLON as Trustee
 
  By:  
    as Authenticating Agent”

 

Article VIII

HOLDERS LISTS AND COMMUNICATIONS BY TRUSTEE AND ISSUER

 

Section 8.1.          Issuer to Furnish Trustee; Names and Addresses of Holders.

 

The Issuer will furnish or cause to be furnished to the Trustee

 

(a)               semi-annually, not more than 15 days after each Regular Record Date, a list, in such form as the Trustee may reasonably require, of the names and addresses of the Holders as of such Regular Record Date; and

 

(b)               at such other times as the Trustee may request in writing, within 30 days after the receipt by the Issuer of any such request, a list of similar form and content as of a date not more than 15 days prior to the time such list is furnished;

 

excluding from any such list names and addresses received by the Trustee in its capacity as Registrar.

 

Section 8.2.          Preservation of Information; Communications to Holders.

 

(a)               The Trustee shall preserve, in as current a form as is reasonably practicable, the names and addresses of Holders contained in the most recent list furnished to the Trustee as provided in Section 8.1 and the names and addresses of Holders received by the Trustee in its capacity as Registrar. The Trustee may destroy any list furnished to it as provided in Section 8.1 upon receipt of a new list so furnished.

 

(b)               If a Holder (herein referred to as an “applicant”) applies in writing to the Trustee, and furnishes to the Trustee reasonable proof that each such applicant has owned a Note for a period of at least six months preceding the date of such application, and such application states that such applicant desires to communicate with other Holders with respect to their rights under this Indenture or under the Notes and is accompanied by a copy of the form of proxy or other communication which such applicant proposes to transmit, then the Trustee shall, within five Business Days after the receipt of such application, at its election, either

 

(1)               afford such applicant access to the information preserved at the time by the Trustee in accordance with Section 8.2(a); or

 

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(2)               inform such applications as to the approximate number of Holders whose names and addresses appear in the information preserved at the time by the Trustee in accordance with Section 8.2(a), as to the approximate cost of mailing to such Holders the form of proxy or other communication, if any, specified in such application.

 

(c)               Every Holder of Notes, by receiving and holding the same, agrees with the Issuer and the Trustee that neither the Issuer nor the Trustee nor any agent of either of them shall be held accountable by reason of the disclosure of any such information as to the names and addresses of the Holders in accordance with Section 8.2(b), regardless of the source from which such information was derived, and that the Trustee shall not be held accountable by reason of mailing any material pursuant to a request made under Section 8.2(b).

 

Article IX

CONSOLIDATION, MERGER, CONVEYANCE, TRANSFER OR LEASE

 

Section 9.1.          Mergers, Consolidations and Certain Sales of Assets.

 

So long as any of the Notes are Outstanding, neither the Issuer nor any Guarantor may, in a single transaction or a series of related transactions:

 

(1)               unless the Issuer or such Guarantor, as applicable, is the surviving Person, consolidate with or merge into any other Person or permit any other Person to consolidate with or merge into the Issuer or such Guarantor, as applicable, (other than a consolidation or merger of a Wholly Owned Subsidiary organized under the laws of Luxembourg, Brazil, Peru, the United States or any OECD country, in each case, with or into the Issuer or such Guarantor, as applicable); or

 

(2)               directly or indirectly, transfer, sell, lease or otherwise dispose of all or substantially all of its assets (determined on a consolidated basis of the Issuer and its Subsidiaries or the relevant Guarantor and its Subsidiaries, as applicable) to any Person (other than the Issuer or a Guarantor) (provided that the creation of a Lien on or in any of its assets shall not in and of itself constitute the transfer, sale, lease or disposition of the assets subject to the Lien),

 

unless the following conditions, to the extent applicable, are met:

 

(i)                 in the case of a transaction in which the Issuer or a Guarantor does not survive or in which the Issuer or a Guarantor sells, leases or otherwise disposes of all or substantially at of its assets to any other Person, the successor entity to the Issuer or such Guarantor (1) shall expressly assume, by a supplemental indenture executed and delivered to the Trustee, all of the Issuer’s or such Guarantor’s obligations under this Indenture and (2) shall be organized under the laws of (x) Luxembourg, Brazil, Peru or any state or political subdivision thereof, (y) the United States or any state thereof or the District of Columbia or (z) any other country if such successor entity undertakes, in such supplemental indenture, to pay such additional amounts in respect of principal (and premium, if any) and interest as may be necessary in order that the net amounts paid pursuant to the Notes after deduction or withholding of any present or future withholding taxes, levies, imposts or charges whatsoever imposed by or for the account of such country or any political subdivision or taxing authority thereof or therein shall equal the respective amounts of principal (and premium, if any) and interest specified in the Notes, subject to the same exceptions set forth under clauses (1) through (7) of Section 11.9, but replacing existing references in such clauses to the jurisdiction of incorporation of the Issuer or such Guarantor, as applicable, with references to such other country and references to the jurisdiction of incorporation of the Issuer or such Guarantor, as applicable, under Section 4.1 shall automatically be deemed to be references to such other country;

 

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(ii)              if, as a result of any such transaction, property or assets of the Issuer or such Guarantor would become subject to a Lien prohibited by Section 12.10, the Issuer or such Guarantor, as applicable, or the successor entity to the Issuer or such Guarantor, as applicable, shall have secured the Notes as described thereunder; and

 

(iii)            the Issuer or such Guarantor, as applicable, has delivered to the Trustee an Officer’s Certificate and an Opinion of Counsel, each stating that such consolidation, merger, conveyance, transfer, lease or acquisition and, if a supplemental indenture is required in connection with such transaction, such supplemental indenture complies with this covenant and that all conditions precedent provided for in this Indenture relating to such transaction have been complied with.

 

In the event of any transaction (other than a lease) described in and complying with the provisions of this Section 9.1 in which the Issuer or a Guarantor, as applicable, is not the surviving Person and the surviving Person assumes all the obligations of the Issuer or such Guarantor, as applicable, under this Indenture and the Notes or the Guarantee, as applicable, pursuant to a supplemental Indenture, such surviving Person shall succeed to, and be substituted for, and may exercise every right and power of, the Issuer or such Guarantor, as applicable, and the Issuer or such Guarantor, as applicable, will be discharged from its obligations under this Indenture and the Notes or the Guarantee, as applicable.

 

Article X

SUPPLEMENTAL INDENTURES

 

Section 10.1.      Supplemental Indentures Without Consent of Holders.

 

Without the consent of any Holders, the Issuer and the Trustee, at any time and from time to time, may enter into one or more supplemental indentures hereto in form satisfactory to the Trustee, for any of the following purposes:

 

(1)               to evidence the succession of another Person to the Issuer or any Guarantor and the assumption by any such successor of the covenants of the Issuer or any Guarantor, as applicable, herein and in the Notes or the Guarantees, as applicable;

 

(2)               to add to the covenants of the Issuer for the benefit of the Holders, or to surrender any right or power herein conferred upon the Issuer;

 

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(3)               to cure any ambiguity, defect or inconsistency or to correct a manifest error;

 

(4)               to provide for uncertificated Notes in addition to or in place of certificated Notes;

 

(5)               to comply with Section 9.1 of this Indenture;

 

(6)               to evidence and provide for the acceptance of an appointment by a successor trustee;

 

(7)               to provide for any additional guarantee of the Notes;

 

(8)               to secure the Notes or to confirm and evidence the release, termination or discharge of any guarantee of or Lien securing the Notes when such release, termination or discharge is permitted by this Indenture;

 

(9)               to provide for or confirm the issuance of Additional Notes;

 

(10)            to conform the provisions of this Indenture to the caption entitled “Description of the Notes” in the offering memorandum relating to the Notes; or

 

(11)           to make any other modification and any waiver or authorization of any breach or proposed breach of any provision of this Indenture or the Notes which is not materially prejudicial to the Holders.

 

Section 10.2.      Supplemental Indentures with Consent of Holders.

 

With the consent of the Holders of not less than a majority in aggregate principal amount of the Outstanding Notes, by Act of said Holders delivered to the Issuer and the Trustee, and consistent with Section 6.13, the Issuer and the Trustee may enter into an indenture or supplemental indentures hereto for the purpose of adding any provisions to or changing in any manner or eliminating any of the provisions of this Indenture or of modifying in any manner the rights of the Holders under this Indenture; provided, however, that no such supplemental indenture shall, without the consent of the Holder of each outstanding Note affected thereby:

 

(1)               change the Stated Maturity of the principal of, or any installment of interest on, any Note, or reduce the principal amount thereof or the rate of interest thereon or any premium payable thereon, or change the place of payment where, or the coin or currency in which, any Note or any premium or interest thereon is payable, or impair the right to institute suit for the enforcement of any such payment on or with respect to any Note on or after the Stated Maturity thereof (or, in the case of redemption, on or after the Redemption Date),

 

(2)               reduce the percentage in principal amount of the Outstanding Notes, the consent of whose Holders is required for any such supplemental indenture, or the consent of whose Holders is required for any waiver (of compliance with certain provisions of this Indenture or certain defaults hereunder and their consequences) provided for in this Indenture;

 

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(3)               modify any of the provisions of this Section 10.2 or Section 6.12 or Section 11.9, except to increase any such percentage described in clause (2) above or to provide that certain other provisions of this Indenture cannot be modified or waived without the consent of the Holder of each Outstanding Note affected thereby;

 

(4)               release any Guarantors from its obligations under its Guarantee or this Indenture, except in compliance with the terms of this Indenture.

 

It shall not be necessary for any Act of Holders under this Section to approve the particular form of any proposed supplemental indenture, but it shall be sufficient if such Act shall approve the substance thereof.

 

Section 10.3.      Execution of Supplemental Indentures.

 

In executing, or accepting the additional trusts created by, any supplemental indenture permitted by this Article or the modifications thereby of the trusts created by this Indenture, the Trustee shall receive, and (subject to Section 7.1) shall be fully protected in conclusively relying upon, in addition to the documents required by Section 1.2, an Officer’s Certificate and Opinion of Counsel stating that the execution of such supplemental indenture is authorized or permitted by this Indenture. The Trustee may, but shall not be obligated to, enter into any such supplemental indenture which affects the trustee’s own rights, duties or immunities under this Indenture.

 

Section 10.4.      Effect of Supplemental Indentures.

 

Upon the execution of any supplemental indenture under this Article, this Indenture shall be modified in accordance therewith, and such supplemental indenture shall form a part of this Indenture for all purposes; and every Holder of Notes theretofore or thereafter authenticated and delivered hereunder shall be bound thereby.

 

Section 10.5.      Reference in Notes to Supplemental Indentures.

 

Notes authenticated and delivered after the execution of any supplemental indenture pursuant to this Article may, and shall if required by the Trustee, bear a notation in form approved by the Trustee as to any matter provided for in such supplemental indenture. If the Issuer shall so determine, new Notes so modified as to conform, in the opinion of the Issuer, to any such supplemental indenture may be prepared and executed by the Issuer and authenticated and delivered by the Trustee in exchange for Outstanding Notes.

 

Section 10.6.      Notice to Holders.

 

After a supplemental indenture under this Article becomes effective, the Issuer will send to the Holders affected thereby a notice briefly describing the terms of the supplement. The Issuer will send supplemental indentures to Holders upon request. Any failure of the Issuer to send such notice, or any defect therein, will not, however, in any way impair or affect the validity of any such supplemental indenture.

 

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Article XI

 

COVENANTS

 

Section 11.1.      Payment Under the Notes.

 

Each of the Issuer and the Guarantors shall duly and punctually pay all amounts owed by it, and comply with all its other obligations, under the terms of the Notes, the Guarantees and this Indenture (collectively, the “Transaction Documents”).

 

Section 11.2.      Maintenance of Office or Agency.

 

The Issuer and the Guarantors will maintain in the Borough of Manhattan, The City of New York, New York, an office or agency where Notes may be presented or surrendered for payment, where Notes may be surrendered for registration of transfer or exchange and where notices and demands to or upon the Issuer or the Guarantors in respect of the Notes, the Guarantees and this Indenture may be served. Initially, this office will be at the Corporate Trust Office of the Trustee, unless the Issuer shall designate and maintain any other office or agency for one or more such purposes, and the Issuer and the Guarantors shall agree not to change the designation of such office without prior written notice to the Trustee and designation of a replacement office in the same general location. The Issuer will give prompt written notice to the Trustee of the location, and any change in the location, of such offices or agencies. If at any time the Issuer or the Guarantors shall fail to maintain any such required offices or agencies or shall fail to furnish the Trustee with the address thereof, such presentations, surrenders, notices and demands may be made or served at the Corporate Trust Office of the Trustee. The Issuer and the Guarantors hereby appoint the Trustee as their agent to receive all such presentations, surrenders, notices and demands.

 

The Issuer may also from time to time designate one or more other offices or agencies (in or outside the Borough of Manhattan, The City of New York, New York) where the Notes may be presented or surrendered for any or all such purposes and may from time to time rescind such designations (each, a “Transfer Agent”); provided, however, that no such designation or rescission shall in any manner relieve the Issuer of its obligation to maintain an office or agency in the Borough of Manhattan, The City of New York, New York. The Issuer has initially designated the offices of The Bank of New York Mellon to act as Transfer Agent. The Issuer will give prompt written notice to the Trustee of any such designation or rescission and of any change in the location of any such other office or agency.

 

Section 11.3.      Money for Note Payments to Be Held in Trust.

 

If the Issuer shall at any time act as its own Paying Agent, it will, on or before each due date of the principal of (and premium, if any) or interest on any of the Notes, segregate and hold in trust for the benefit of the Persons entitled thereto a sum sufficient to pay the principal (and premium, if any) or interest so becoming due until such sums shall be paid to such Persons or otherwise disposed of as herein provided and will promptly notify the Trustee in writing of its action or failure so to act.

 

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Whenever the Issuer shall have one or more Paying Agents, it will, prior to each due date of the principal of (and premium, if any) or interest on any Notes, deposit with the Principal Paying Agent a sum sufficient to pay the principal (and premium, if any) or interest (including Additional Amounts, if any) so becoming due, such sum to be held in trust for the benefit of the Persons entitled to such principal, premium or interest, and (unless such Paying Agent is the Trustee) the Issuer will promptly notify the Trustee in writing of its action or failure so to act.

 

The Issuer will cause each Paying Agent other than the Trustee and the Principal Paying Agent to execute and deliver to the Trustee an instrument in which such Paying Agent shall agree with the Trustee, subject to the provisions of this Section 11.3, that such Paying Agent will:

 

(1)               hold all sums held by it for the payment of the principal of (and premium, if any) or interest on Notes in trust for the benefit of the Persons entitled thereto until such sums shall be paid to such Persons or otherwise disclosed of as herein provided;

 

(2)               give the Trustee written notice of any default by the Issuer (or any other obligor upon the Notes) in the making of any payment of principal (and premium, if any) or interest;

 

(3)              at any time during the continuance of any such default, upon the written request of the Trustee, forthwith pay to the Trustee all sums so held in trust by such Paying Agent; and

 

(4)             acknowledge, accept and agree to comply in all respects with the provisions of this Indenture relating to the duties, rights and obligations of such Paying Agent.

 

The Issuer may at any time, for the purpose of obtaining the satisfaction and discharge of this Indenture or for any other purpose, pay, or by Issuer Order direct any Paying Agent to pay, to the Trustee all sums held in trust by the Issuer or such Paying Agent, such sums to be held by the Trustee upon the same trusts as those upon which such sums were held by the Issuer or such Paying Agent; and, upon such payment by any Paying Agent to the Trustee, such Paying Agent shall be released from all further liability with respect to such money.

 

Any money deposited with the Trustee or any Paying Agent, or then held by the Issuer, in trust for the payment of the principal of (and premium, if any) or interest on any Note and remaining unclaimed for two years after such principal (and premium, if any) or interest has become due and payable shall be paid to the Issuer on the Issuer’s Request, or (if then held by the Issuer) shall be discharged from such trust; and the Holder of such Note shall thereafter, as an unsecured general creditor, look only to the Issuer for payment thereof, and all liability of the Trustee or such Paying Agent with respect to such trust money, and all liability of the Issuer as trustee thereof, shall thereupon cease.

 

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Section 11.4.      Maintenance of Corporate Existence.

 

The Issuer and the Guarantors shall, and shall cause each of their respective Subsidiaries to, maintain in effect its corporate existence and all registrations necessary therefore and take all actions to maintain all rights, privileges, titles to property, franchises and the like necessary or desirable in the normal conduct of its business, activities or operations provided that this covenant shall not require (i) the Issuer, the Guarantors or any of their respective Subsidiaries to maintain any such registration, right, privilege, title to property, franchise or the like or require the Issuer or the Guarantors to preserve the corporate existence of any of their respective Subsidiaries (other than a Subsidiary that is a Guarantor), if the failure to do so would not have a material adverse effect on the Issuer and its Subsidiaries taken as a whole or have a material adverse effect on the rights of the Holders or (ii) the Guarantors or the Issuer to preserve its corporate existence if it complies with the provisions of Section 9.1.

 

Section 11.5.      Repurchases at the Option of the Holders upon Change of Control.

 

If a Change of Control occurs that results in a Rating Decline, each Holder will have the right to require the repurchase of all or any part (equal to U.S.$200,000 and integral multiples of U.S.$1,000 in excess thereof) of the Notes of that Holder pursuant to a Change of Control Offer by the Issuer or the Guarantors. No such purchase in part shall reduce the principal amount of the Notes held by any Holder to below U.S.$200,000. In the Change of Control Offer, the Issuer or a Guarantor will offer a “Change of Control Payment” in U.S. dollars equal to 101% of the aggregate principal amount of Notes repurchased plus accrued and unpaid interest and Additional Amounts, if any, on the Notes repurchased, to the date of purchase (subject to the right of the Holders of record on the relevant Record Date to receive interest and Additional Amounts, if any, on the relevant Interest Payment Date).

 

Within 30 days following any Change of Control that results in a Rating Decline the Issuer or the Guarantor will make a “Change of Control Offer” by notice to each Holder of Notes in accordance with the provision set out under Section 1.6, describing the transaction or transactions that constitute the Change of Control and offering to repurchase Notes on the date specified in the notice (the “Change of Control Payment Date”), which date will be no earlier than 30 days and no later than 60 days from the date such notice is mailed, pursuant to the procedures required by this Indenture and described in such notice.

 

The Issuer or the applicable Guarantor will comply, to the extent applicable, with the requirements of Section 14(e)-1 of the Exchange Act and any other applicable securities laws or regulations in connection with the repurchase of Notes pursuant to this covenant. To the extent that the provisions of any applicable securities laws or regulations conflict with provisions of this covenant, the Issuer or the applicable Guarantor will comply with the applicable securities laws and regulations and will not be deemed to have breached its obligations under this covenant by virtue of its compliance with such securities laws or regulations.

 

On the Change of Control Payment Date, the Issuer or the applicable Guarantor will, to the extent lawful:

 

(1)               accept for payment all Notes or portions of Notes properly tendered pursuant to the Change of Control Offer; and

 

(2)               procure that the Change of Control Payment is made in respect of all Notes or portions of Notes properly tendered.

 

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The Paying Agents will promptly mail to each Holder who properly tendered Notes the Change of Control Payment for such Notes, and the Trustee will promptly authenticate and mail (or cause to be transferred by book entry) to each Holder a new Note equal in principal amount to any unpurchased portion of the Notes surrendered, if any; provided that each new Note will be in minimum denominations of U.S.$200,000 and integral multiples of U.S.$1,000 in excess thereof.

 

The provisions described above that require the Issuer or a Guarantor to make a Change of Control Offer following a Change of Control will be applicable whether or not any other provisions of this Indenture are applicable. However, a Change of Control Offer is only required to be made in the event that a Change of Control results in a Rating Decline. Consequently, if a Change of Control were to occur which does not result in a Rating Decline, none of the Issuer and the Guarantors would be required to launch a Change of Control Offer. Except as described above with respect to a Change of Control, this Indenture does not contain provisions that permit the Holders to require that the Issuer or a Guarantor repurchase or redeem the Notes in the event of a takeover, recapitalization or similar transaction.

 

None of the Issuer or the Guarantors will be required to make a Change of Control Offer upon a Change of Control if (1) a third party makes the Change of Control Offer in the manner, at the times and otherwise in compliance with the requirements, set forth in this Indenture, that are applicable to a Change of Control Offer made by the Issuer or a Guarantor and such third party purchases all Notes properly tendered and not withdrawn under the Change of Control Offer or (2) a notice of redemption has been given for all outstanding Notes pursuant to this Indenture as described under Section 4.2 unless and until there is a default in payment of the applicable redemption price.

 

Notwithstanding anything to the contrary contained herein and subject to applicable law, a Change of Control Offer may be made in advance of a Change of Control and conditioned upon the occurrence of such Change of Control and Rating Decline if a definitive agreement is in place for the Change of Control at the time of making of the Change of Control Offer.

 

In the event that the Holders of not less than 90% of the aggregate principal amount of Outstanding Notes accept a Change of Control Offer and the Issuer or a Guarantor or a third party purchases all the Notes held by such holders, the Issuer or a Guarantor will have the right, on not less than 30 nor more than 60 days’ prior notice to the Holders, given not more than 30 days following the purchase date pursuant to the Change of Control Offer, to redeem all of the Notes that remain outstanding following such purchase at the purchase price equal to that in the Change of Control Offer plus, to the extent not included in the purchase price, accrued and unpaid interest and additional amounts, if any, on the Notes that remain Outstanding, to, but excluding, the date of redemption.

 

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Section 11.6.      Payment of Taxes and Other Claims.

 

The Issuer and the Guarantors shall, and shall cause each of their respective Subsidiaries to, pay or discharge or cause to be paid or discharged before the same shall become delinquent, (i) all taxes, assessments and governmental charges levied or imposed upon the Issuer and the Guarantors or any of their respective Subsidiaries, as the case may be, and (ii) all lawful claims for labor, materials and supplies which, if unpaid, might by law become a lien upon the property of the Issuer or a Guarantor or any of their respective Subsidiaries, as the case may be; provided, however, that neither the Issuer nor any Guarantor nor any of their respective Subsidiaries shall be required to pay or discharge or cause to be paid or discharged any such tax, assessment, charge or claim whose amount, applicability or validity is being contested in good faith and, if appropriate, by appropriate legal proceedings, or where the failure to do so would not have a material adverse effect on the Issuer and its Subsidiaries taken as a whole or have a material adverse effect on the rights of the Holders.

 

Section 11.7.      Provision of Financial Information.

 

The Issuer has agreed that it will furnish to the Trustee and the Holders and to any prospective purchasers of such Notes, to the extent permitted by applicable law or contractual restrictions, upon their request, the information required to be delivered pursuant to Rule 144A(d)(4) under the Securities Act; provided that the foregoing obligation will only apply to the Issuer if it ceases to be subject to and in compliance with the reporting requirements of Section 13 or 15(d) of the Exchange Act or exempt from reporting pursuant to Rule 12g3-2(b) under the Exchange Act.

 

Additionally, the Issuer shall provide the Trustee and the Holders, within 120 days of the end of each fiscal year and within 60 days of the end of each of the first three fiscal quarters, annual or quarterly financial statements, as applicable, in accordance with applicable GAAP and audited in the case of annual financial statements.

 

Notwithstanding the foregoing, if the Issuer makes available the information described above on the Issuer’s or an Affiliate’s website or on the Electronic Data Gathering, Analysis, and Retrieval (EDGAR) website of the SEC, the Issuer will be deemed to have satisfied the reporting requirement set forth in such applicable clause. It is understood that the Trustee shall have no responsibility to determine whether any information has been posted on such websites.

 

Delivery of such reports, information and documents to the Trustee is for informational purposes only and the Trustee’s receipt of such reports shall not constitute constructive notice of any information contained therein or determinable from information contained therein, including the Issuer’s compliance with any of its covenants hereunder (as to which the Trustee is entitled to rely exclusively on an Officer’s Certificate or notice). The Trustee shall have no obligation to determine if and when the Issuer’s statements or reports are publicly available and accessible electronically.

 

Section 11.8.      Statement by Officers as to Default.

 

(a)               The Issuer will be required to furnish to the Trustee together with the delivery (or the posting on the Issuer’s or an Affiliate’s website) of its annual financial statements and in any event within 120 days after the end of each such fiscal period, an Officer’s Certificate statin whether or not to the best knowledge of the signer thereof none of the Issuer or any Guarantor is in default in the performance and observance of any of the terms, provisions and conditions of this Indenture and if the Issuer or any Guarantor is in default, specifying all such defaults and the nature and status thereof of which they may have knowledge.

 

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(b)               The Issuer shall deliver to the Trustee, as soon as is practicable and in any event within ten calendar days after the Issuer becomes aware of the occurrence of a Default or an Event of Default, an Officer’s Certificate of the Issuer, setting forth the details of such Default or Event of Default and stating what action the Issuer, proposes to take with respect thereto. None of the Agents shall have notice of any Default or Event of Default unless a Responsible Officer of such Agent has actual knowledge thereof.

 

Section 11.9.      Payment of Additional Amounts.

 

Any and all payments to a Holder of principal (and premium, if any) and interest in respect of the Notes, and any and all payments to indemnify a Holder for taxes or duties as a result of a substitution of the issuer, as provided in Section 13.1(a)(2), will be made free and clear of, and without withholding or deduction for, any and all present and future withholding taxes, duties, assessments, levies, imposts or charges (“Taxes”) whatsoever imposed by or on behalf of, Luxembourg, Brazil, Peru or any political subdivision or taxing authority thereof or therein, unless such withholding or deduction is required by law. In that event, the Issuer or a Guarantor, as the case may be, shall pay such additional amounts (the “Additional Amounts”) as will result in the receipt by the Holders of such amounts as would have been received by them if no such withholding or deduction had been required, except that no such Additional Amounts shall be payable in respect of any Note:

 

(1)               held by, or by a third party on behalf of, a Holder or beneficial owner which is liable for such taxes, duties, assessments, levies, imposts or governmental charges in respect of such Note by reason of its (or a fiduciary, settlor, member or shareholder, beneficiary of, or possessor of a power over, such Holder, if such Holder is an estate, trust, partnership or corporation) having some present or former connection with Luxembourg, Brazil or Peru (including being or having been a citizen or resident of Luxembourg, Brazil or Peru or being or having been engaged in trade or business therein) other than the mere holding of such Note; or

 

(2)               where (in the case of a payment of principal, premium, if any, or interest on the Maturity Date or date of earlier redemption) the relevant Note is surrendered for payment more than 30 days after the Relevant Date except to the extent that the relevant Holder would have been entitled to such Additional Amounts if it had surrendered the relevant Note on the last day of such period of 30 days; or

 

(3)               if such Tax is an estate, inheritance, gift, sales, transfer or personal property tax or any similar Tax, assessment, levy, impost or governmental charge; or

 

(4)                 if such amount is (a) payable other than by withholding or deduction from a payment on such Note, or (b) required to be withheld or deducted by a Paying Agent and such Holder of a Note would have been able to avoid such withholding or deduction by presenting the relevant Note to another Paying Agent; or

 

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(5)              if such Tax, duty, assessment, levy, impost or governmental charge would not have been imposed but for the failure of such Holder to comply with applicable certification, information, documentation or other reporting requirements concerning the nationality, residence, identity or connection with Luxembourg, Brazil or Peru of the Holder or beneficial owner of such Note if (i) such compliance is required as a precondition to relief or exemption from withholding or deduction of all or part of such tax, duty, assessment, levy, impost or governmental charge and (ii) at least 30 days prior to the date on which the Issuer or a Guarantor, as the case may be, applies this clause (5), it will have notified such Holder or beneficial owner of a Note that it will be required to comply with such requirement; or

 

(6)               if such amount to be paid with respect to a payment on a note to a Holder that is a fiduciary or partnership or other than the sole beneficial owner of such payment to the extent a beneficiary or settlor with respect to such fiduciary or a member of such partnership or a beneficial owner would not have been entitled to the additional interest had such beneficiary, settlor, member or beneficial owner been the Holder of such note; or

 

(7)               in the case of any combination of items (1) through (6).

 

Relevant Date” means whichever is the later of (a) the date on which the payment in question first becomes due and (b) if the full amount payable has not been received by the Principal Paying Agent on or prior to such due date, the date on which (the full amount having been so received) notice to that effect has been given to the Holders.

 

None of the Issuer, a Guarantor, the Trustee, any Paying Agent or any other person shall be required to pay any Additional Amounts with respect to any withholding or deduction imposed on or in respect of any Note pursuant to FATCA, any treaty, law, regulation or other official guidance enacted by any jurisdiction implementing FATCA, or any agreement between the Issuer and the United States or any authority thereof implementing FATCA.

 

The Issuer or the relevant Guarantor, as applicable, shall pay any present or future stamp, court or documentary taxes, or any other excise or property taxes, charges or similar levies which arise in any jurisdiction from the execution, delivery or registration of the Notes or any other document or instrument referred to therein, excluding any such taxes, charges or similar levies imposed by any jurisdiction outside of Luxembourg, Brazil or Peru, as applicable, except those resulting from, or required to be paid in connection with, (i) the execution in or bringing to Luxembourg, Brazil or Peru, as applicable, of the Notes or any document or instrument; (ii) the production before a court of Luxembourg, Brazil or Peru of the Notes or any document or instrument or (iii) the enforcement of the Notes or any other such document or instrument following the occurrence of any Event of Default with respect to the Notes.

 

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References to principal or interest shall be deemed to include any Additional Amounts in respect of principal, premium, if any, or interest (as the case may be) which may be payable under the Notes.

 

If the Issuer or a Guarantor becomes subject at any time to any taxing jurisdiction other than Luxembourg, Brazil or Peru, references herein to Luxembourg, Brazil or Peru, as applicable, shall be construed to include such other jurisdiction.

 

The Trustee shall have no obligation to determine whether any Additional Amounts are owed or for the calculation thereof.

 

Section 11.10.  Limitation on Liens.

 

The Issuer shall not, and shall not permit any of its Designated Subsidiaries to, Incur or suffer to exist any Lien on any of its Restricted Property to secure any Indebtedness of the Issuer or such Designated Subsidiary without making, or causing such Designated Subsidiary to make, effective provision for securing the Notes (x) equally and ratably with (or prior to) such Indebtedness as to such Restricted Property for so long as such Indebtedness will be so secured or (y) in the event such Indebtedness is Indebtedness of the Issuer or such Designated Subsidiary which is subordinate in right of payment to the Notes, prior to such Indebtedness as to any such Restricted Property for so long as such Indebtedness will be so secured.

 

The foregoing restrictions shall not apply to:

 

(1)               any Lien on the inventory or receivables and related assets (other than those described in clause (3) below) securing obligations:

 

(i)               under any short term lines of credit, entered into in the normal course of business; or

 

(ii)              under any working capital facility;

 

(2)               Liens created solely for the purpose of securing the payment of all or a part of the purchase price (or the cost of construction or improvement, and any related transaction fee and expenses) of assets or property (including Capital Stock of any Person) acquired, constructed or improved after the Issue Date; provided that (a) the aggregate principal amount of Indebtedness secured by such Liens shall not exceed the purchase price of the assets or property so acquired, constructed or improved, (b) such Liens shall not encumber any assets or property other than the assets or property so acquired, constructed or improved and other than any unimproved real property on which the property so constructed, or the improvement, is located and (c) such Lien shall attach to such assets or property within 365 days of the construction, acquisition or improvement of such assets or property; provided, further, that to the extent that the property or asset acquired is Capital Stock, and subject to the limitations in clause (c) above, the Lien also may encumber other property or assets of the Person so acquired, provided, further, that any Lien is permitted to be incurred on the Capital Stock of any Person securing any Indebtedness of that Person that is (a) non-recourse to the Issuer or the Designated Subsidiary, and (b) incurred solely for purposes of financing the acquisition, construction or improvement of any property or assets of such Person;

 

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(3)               Liens on accounts receivable and related assets in connection with any credit facility, including export or import financings and other trade transactions, or in connection with any Securitization Transaction provided that the aggregate amount of any Receivables sold or transferred in such Securitization Transaction securing Indebtedness shall not exceed (a) with respect to transactions related to revenues from exports, 80% of such Person’s consolidated net sales from exports; or (b) with respect to transactions related to revenues from domestic sales, 80% of such Person’s consolidated net sales in the jurisdiction in which such Person is located;

 

(4)              Liens granted to secure borrowings from (i) Banco Nacional de Desenvolvimento Econômico e Social-BNDES, or any other federal, regional or state governmental development bank or credit agency, or (ii) any international or multilateral development bank, government-sponsored agency, export-import bank or official export-import credit insurer;

 

(5)                 Liens existing on the Issue Date;

 

(6)              Liens on property or shares of Capital Stock of another Person at the time such other Person becomes a Subsidiary; provided, however, that the Liens may not extend to any other property owned by such Person;

 

(7)                 Liens on properly at the time such Person or any of its Subsidiaries acquires the property, including any acquisition by means of a merger or consolidation with or into such Person or a Subsidiary of such Person; provided, however, that the Liens may not extend to any other property owned by such Person;

 

(8)              Liens securing Indebtedness or other obligations of a Subsidiary of such Person owing to such Person or a Subsidiary of such Person;

 

(9)              Liens in favor of surety bonds or letters of credit issued pursuant to the request of, and for the account of, such Person in the ordinary course of its business;

 

(10)            any Lien securing obligations owed to the Peruvian Ministry of Energy and Mines or other governmental authorities incurred in the ordinary course of business, including but not limited to, mine closure plans;

 

(11)              Liens securing obligations under hedging agreements not for speculative purposes;

 

(12)              any Lien extending, renewing or replacing (or successive extensions, renewals or replacements of), in whole or in part, any Lien referred to in clauses (2), (4), (5), (6) or (7) above; provided that the principal amount of Indebtedness secured thereby shall not exceed the principal amount of Indebtedness so secured at the time of such extension, renewal or replacement except for any increase reflecting premiums, fees and expenses in connection with such extension, renewal or replacement, and that such extension, renewal or replacement shall be limited to all or a part of the property which secured the Lien so extended, renewed or replaced (plus improvements on such property); and

 

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(13)           Lien that do not fall within clauses (1) through (12) above and that secure Indebtedness which, exclusive of Indebtedness secured by other Liens permitted under this covenant, does not exceed an aggregate principal amount equal to 15% of Consolidated Total Assets.

 

For the avoidance of doubt, a Lien permitted by this Section 11.10 need not be permitted solely by reference to a single clause permitting such Lien, but may be permitted in part by such clause and in part by one or more other clauses of this covenant otherwise permitting such Lien.

 

Section 11.11.  [Intentionally Omitted].

 

Section 11.12.  Performance Obligations Under Other Documents.

 

The Issuer shall duly and punctually perform, comply with and observe all obligations and agreements to be performed by it set forth in the Transaction Documents.

 

Section 11.13.  Compliance with Laws.

 

Each of the Issuer and the Guarantors shall comply, and shall cause their respective Subsidiaries to comply, at all times with all applicable laws, rules, regulations, orders and directives of any government or government agency or authority having jurisdiction over the Issuer or any Guarantors, any of their respective Subsidiaries or the business of any of them or any of the transactions contemplated herein, except where the failure to do so would not have a material adverse effect on the Issuer and its Subsidiaries taken as a whole or have a material adverse effect on the rights of the Holders.

 

Section 11.14.  Maintenance of Government Approvals.

 

Each of the Issuer and the Guarantors shall, and shall cause their respective Subsidiaries to, duly obtain and maintain in full force and effect all governmental approvals, consents or licenses of any government or governmental agency or authority under the laws of Luxembourg, Brazil, Peru (including any Central Bank) or any other government or government agency having jurisdiction over the Issuer or necessary in all cases for the Guarantors and the Issuer to perform their respective obligations under the Transaction Documents or for the validity or enforceability thereof, except where the failure to do so would not have a material adverse effect on the Issuer and its Subsidiaries taken as a whole or have a material adverse effect on the rights of the Holders.

 

Section 11.15.  [Intentionally Omitted].

 

Section 11.16.  Maintenance of Books and Records.

 

Each of the Issuer and the Guarantors shall, and shall cause each of their respective Subsidiaries to, maintain books, accounts and records in all material respects in accordance with applicable GAAP, and in any case in the manner necessary to facilitate consolidation into the Guarantors’ consolidated financial statements.

 

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Section 11.17.  Ranking.

 

The Issuer shall ensure that the Notes will constitute unsecured and unsubordinated obligations of the Issuer, and will rank at least equally to all other present and future unsecured and unsubordinated obligations of the Issuer (other than obligations preferred by statute or by operation of law). Each of the Guarantors shall ensure that its Guarantee will constitute unsecured and unsubordinated obligations of such Guarantor, and will rank at least equally to all other present and future unsecured and unsubordinated obligations of the Guarantors (other than obligations preferred by statute or by operation of law). No obligation will be considered to be senior to the Notes or the Guarantees by virtue of being secured on a first or junior priority basis.

 

Article XII

LEGAL DEFEASANCE AND COVENANT DEFEASANCE

 

Section 12.1.      Option to Effect Defeasance or Covenant Defeasance.

 

The Issuer or a Guarantor may at its option, at any time elect to have either Section 12.2 or Section 12.3 applied to the Outstanding Notes upon compliance with the conditions set forth below in this Article XII.

 

Section 12.2.      Defeasance and Discharge.

 

Upon the Issuer’s or a Guarantor’s exercise of the option provided in Section 12.1 applicable to this Section, the Issuer and a Guarantor shall be deemed to have been discharged from their obligations with respect to the Outstanding Notes on the date the conditions set forth below are satisfied (hereinafter, “defeasance”). For this purpose, such defeasance means that the Issuer and a Guarantor shall be deemed to have paid and discharged the entire indebtedness represented by the Outstanding Notes and to have satisfied all their other obligations under such Notes and this Indenture insofar as such Notes are concerned (and the Trustee, at the expense of the Issuer and a Guarantor, shall execute proper instruments acknowledging the same), except for the following which shall survive until otherwise terminated or discharged hereunder: (A) the rights of Holders of Outstanding Notes to receive, solely from the trust fund described in Section 12.4 and as more fully set forth in such Section, payments in respect of the principal of (and premium, if any) and interest (and Additional Amounts, if any) on such Notes when such payments are due, (B) the Issuer’s and the Guarantors’ obligations with respect to such Notes under Sections 3.3, 3.4, 3.5, 11.2 and 11.3, (C) the rights, powers, trusts, duties and immunities of the Trustee hereunder and (D) this Article XII. Subject to compliance with this Article XII, the Issuer and the Guarantors may exercise their option under this Section 12.2 notwithstanding the prior exercise of their option under Section 12.3.

 

Section 12.3.      Covenant Defeasance.

 

Upon the Issuer or a Guarantor’s exercise of the option provided in Section 12.1 applicable to this Section, (i) the Issuer and the Guarantors shall be released from their obligations under Sections Section 9.1 and 11.15 through 11.17, inclusive and the Guarantors shall be released from all of its obligations under the Guarantees and under Article XIII of this Indenture, and (ii) the occurrence of an event specified in Section 6.1(3) (with respect to Section 9.1 and Sections 11.15 through 11.17, inclusive) shall not be deemed to be or result in an Event of Default, on and after the date the conditions set forth below are satisfied (hereinafter, “covenant defeasance”). For this purpose, such covenant defeasance means that the Issuer and the Guarantors may omit to comply with and shall have no liability in respect of any term, condition or limitation set forth in any such Section or Article, whether directly or indirectly by reason of any reference elsewhere herein to any such Section or Article or by reason of any reference in any such Section or Article to any other provision herein or in any other document, but the remainder of this Indenture and such Notes shall be unaffected thereby.

 

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Section 12.4.      Conditions to Defeasance or Covenant Defeasance.

 

The following shall be the conditions to application of either Section 12.2 or Section 12.3 to the Outstanding Notes:

 

(1)               the Issuer or a Guarantor shall irrevocably have deposited or caused to be deposited with the Trustee or its designee, in trust, for the benefit of the Holders (A) cash, (B) Cash Equivalents, (C) U.S. Government Obligations, or (D) a combination thereof, sufficient, in the written opinion of an internationally recognized firm of independent certified public accountants, investment bank or consulting firm to pay and discharge, the principal of, premium, if any, and each installment of interest (including Additional Amounts, if any) on the Notes on the Stated Maturity of such principal or installment of interest on the day on which such payments are due and payable in accordance with the terms of this Indenture and of such Notes. For this purpose, “U.S. Government Obligations” means securities that are (x) direct obligations of the United States for the payment of which its full faith and credit is pledged or (y) obligations of a Person controlled or supervised by and acting as an agency or instrumentality of the United States the payment of which is unconditionally guaranteed as a full faith and credit obligation by the United States, which, in either case, are not callable or redeemable at the option of the issuer thereof, and shall also include a depositary receipt issued by a bank (as defined in Section 3(a)(2) of the Securities Act) as custodian with respect to any such U.S. Government Obligation or a specific payment of principal of or interest on any such U.S. Government Obligation held by such custodian for the account of the Holder of such depositary receipt, provided that (except as required by law) such custodian is not authorized to make any deduction from the amount payable to the Holder of such depositary receipt from any amount received by the custodian in respect of the U.S. Government Obligation or the specific payment of principal of or interest on the U.S. Government Obligation evidenced by such depositary receipt;

 

(2)               no Default or Event of Default shall have occurred and be continuing on the date of such deposit;

 

(3)               the Issuer or a Guarantor shall have delivered to the Trustee an Officer’s Certificate and an Opinion of Counsel, each stating that all conditions precedent provided for relating to either the defeasance under Section 12.2 or the covenant defeasance under Section 12.3 (as the case may be) have been complied with;

 

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(4)               in the case of an election under Section 12.2, the Issuer or a Guarantor shall have delivered to the Trustee an Opinion of Counsel in the United States stating that (x) the Issuer or a Guarantor has received from, or there has been published by, the Internal Revenue Service a ruling, or (y) since the date of this Indenture there has been a change in the applicable United States Federal income tax law, in either case to the effect that, and based thereon such Opinion of Counsel shall confirm that, the Holders of the Outstanding Notes will not recognize income, gain or loss for United States Federal income tax purposes as a result of such deposit, defeasance and discharge and will be subject to United States Federal income tax on the same amounts, in the same manner and at the same times as would have been the case if such deposit, defeasance and discharge had not occurred;

 

(5)               in the case of an election under Section 12.3, the Issuer or a Guarantor shall have delivered to the Trustee an Opinion of Counsel in the United States to the effect that the Holders of the Outstanding Notes will not recognize income, gain or loss for United States Federal income tax purposes as a result of such deposit and covenant defeasance and will be subject to United States Federal income tax on the same amounts, in the same manner and at the same times as would have been the case if such covenant defeasance had not occurred.

 

Section 12.5.      Deposited Money and U.S. Government Obligations to Be Held in Trust; Other Miscellaneous Provisions.

 

Subject to the provisions of the last paragraph of Section 11.3, all money and U.S. Government Obligations (including the proceeds thereof) deposited with the Trustee (or other qualifying trustee—collectively, for purposes of this Section 12.5, the “Defeasance Trustee”) pursuant to Section 12.4 in respect of the Notes shall be held in trust and applied by the Defeasance Trustee, in accordance with the provisions of such Notes and this Indenture, to the payment, either directly or through any Paying Agent (including the Issuer or a Guarantor acting as their own Paying Agent) as the Defeasance Trustee may determine, to the Holders of such Notes, of all sums due and to become due thereon in respect of principal (and premium, if any) and interest, but such money need not be segregated from other funds except to the extent required by law.

 

The Issuer and the Guarantors shall, jointly and severally, pay and indemnify the Defeasance Trustee against any tax, fee or other charge imposed on or assessed against the U.S. Government Obligations deposited pursuant to Section 12.4 or the principal and interest received in respect thereof other than any such tax, fee or other charge which by law is for the account of the Holders of the Outstanding Notes.

 

Anything in this Article to the contrary notwithstanding, the Defeasance Trustee shall deliver or pay to the Issuer from time to time upon Issuer Request any money or U.S. Government Obligations held by it as provided in Section 12.4 which, in the opinion of an internationally recognized accounting firm expressed in a written certification thereof delivered to the Defeasance Trustee, are in excess of the amount thereof which would then be required to be deposited to effect an equivalent defeasance or covenant defeasance.

 

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Section 12.6.      Reinstatement.

 

If the Defeasance Trustee or the Paying Agent is unable to apply any money in accordance with Section 12.2 or 12.3 by reason of any order or judgment of any court or governmental authority enjoining, restraining or otherwise prohibiting such application, then the obligations of the Issuer and the Guarantors under this Indenture, the Guarantees and the Notes, if any, shall be revived and reinstated as though no deposit had occurred pursuant to this Article until such time as the Defeasance Trustee or Paying Agent is permitted to apply all such money in accordance with Section 12.2 or 12.3; provided, however, that if the Issuer or the Guarantors makes any payment of principal of (and premium, if any) any Note following the reinstatement of such obligations, the Issuer or the Guarantors shall be subrogated to the rights of the Holders of such Notes to receive such payment from the money held by the Defeasance Trustee or the Paying Agent.

 

Section 12.7.      Repayment to Issuer or the Guarantors.

 

Any money deposited with the Defeasance Trustee or any Paying Agent, or then held by the Issuer or a Guarantor, in trust for the payment of the principal of, premium, if any, or interest on any Note and remaining unclaimed for two years after such principal, and premium, if any, or interest has become due and payable shall be paid to the Issuer or the Guarantors on its written request or (if then held by the Issuer or the Guarantors) shall be discharged from such trust; and the Holder of such security shall thereafter, as a creditor, look only to the Issuer or the Guarantors for payment thereof, and all liability of the Defeasance Trustee or such Paying Agent with respect to such trust money, and all liability of the Issuer or the Guarantor as trustee thereof, shall thereupon cease; provided, however, that the Defeasance Trustee or such Paying Agent, before being required to make any such repayment, shall at the expense of the Issuer and the Guarantors cause to be published once, in The New York Times and The Wall Street Journal (national edition), notice that such money remains unclaimed and that, after a date specified therein, which shall not be less than 30 days from the date of such notification or publication, any unclaimed balance of such money then remaining will be repaid to the Issuer or the Guarantors.

 

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Article XIII

SUBSTITUTION OF THE ISSUER

 

Section 13.1.      Substitution of the Issuer.

 

Notwithstanding any other provision contained in this Indenture,

 

(a)               the Issuer may, without the consent of the Holders of the Notes (and by subscribing for any Notes, each Holder of the Notes expressly consents to it), be replaced and substituted by (i) any Wholly Owned Subsidiary of the Issuer or (ii) any Permitted Holding Company as principal debtor (in such capacity, the “Substituted Issuer”) in respect of the Notes provided that:

 

(1)               such documents (together, the “Issuer Substitution Documents”) shall be executed by the Substituted Issuer, the Issuer and the Trustee as may be necessary to give full effect to the substitution, including a supplemental indenture whereby (i) the Substituted Issuer assumes all Issuer’s obligations under this Indenture and the Notes and (ii) the Issuer (the “Additional Guarantor”) guarantees on an unsecured and unsubordinated basis the due and punctual payment of all amounts under this Indenture and with respect to the Notes (without limiting the generality of the foregoing) pursuant to which the Substituted Issuer shall undertake in favor of each Holder of the Notes to be bound by the terms and conditions of the Notes and the provisions of this Indenture as fully as if the Substituted Issuer had been named in the Notes and this Indenture as the principal debtor in respect of the Notes in place of the Issuer (or any previous substitute) and pursuant to which the Additional Guarantor will guarantee on an unsecured and unsubordinated basis the due and punctual payment of all amounts under this Indenture and with respect to the Notes (together, the “Substitution”);

 

(2)               if the Substituted Issuer is incorporated, domiciled or resident in a territory other than Luxembourg, the Issuer Substitution Documents shall contain a covenant by the Substituted Issuer and/or such other provisions as may be necessary to ensure that each Holder of the Notes has the benefit of a covenant in terms corresponding to the obligations of the Issuer in respect of the payment of Additional Amounts set forth in Section 11.9 and tax repurchases in Section 4.1, with the substitution for the references to Luxembourg for references to the territory in which the Substituted Issuer is incorporated, domiciled and/or resident for taxation purposes;

 

(3)               the Issuer Substitution Documents shall contain a covenant by the Additional Guarantor and/or such other provisions as may be necessary to ensure that each holder of the Notes has the benefit of a covenant in terms corresponding to the obligations of the Additional Guarantor as a guarantor of the Notes in respect of the payment of Additional Amounts set forth in Section 11.9 (but with references to Luxembourg as the jurisdiction of incorporation of the Additional Guarantor);

 

(4)               if the Substituted Issuer is incorporated, domiciled or resident in a territory other than Luxembourg, the Issuer Substitution Documents shall also contain a covenant by the Substituted Issuer to indemnify and hold harmless each Holder and beneficial owner of the Notes, the Trustee, the Agents and each other against the actual amount of all taxes or duties required to be paid (including any taxes or duties imposed on the receipt of such indemnity payments) which arise by reason of a law or regulation in effect or contemplated on the effective date of the Substitution, which may be incurred or levied against such Holder or beneficial owner of the Notes as a result of the substitution and which would not have been so incurred or levied had the Substitution not been made, subject to similar exceptions set forth under Section 11.9(2) through (8), inclusive, mutatis mutandis; provided, that any holder making a claim with respect to such tax indemnity shall provide the Issuer with notice of such claim, along with supporting documentation, within four weeks of the announcement of the Substitution of the Substituted Issuer as issuer; provided further, that none of the Issuer (including the Substituted Issuer), the Guarantors (including the Additional Guarantor), any paying agent or any other person shall be required to indemnify any holder or beneficial owner of the notes for any taxes imposed pursuant to FATCA, any treaty, law, regulation or other official guidance enacted by any jurisdiction implementing FATCA, or any agreement between the Issuer and the United States or any authority thereof implementing FATCA;

 

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(5)               the Substituted Issuer shall have delivered, or procured the delivery to the Trustee of, an Opinion of Counsel addressed to the Substituted Issuer from a leading firm of lawyers in the country of incorporation of the Substituted Issuer, to the effect that the Issuer Substitution Documents constitute legal, valid and binding obligations of the Substituted Issuer and the Additional Guarantor;

 

(6)               the Issuer shall have delivered, or procured the delivery to the Trustee of, an Opinion of Counsel addressed to the Issuer and the Substituted Issuer from a leading firm of New York lawyers to the effect that the Issuer Substitution Documents constitute legal, valid and binding obligations of the Substituted Issuer and the Additional Guarantor under New York law;

 

(7)               the Issuer and the Substituted Issuer shall have appointed a process agent in the Borough of Manhattan, the City of New York to receive service of process on its behalf in relation to any legal action or proceedings arising out of or in connection with the Issuer Substitution Documents;

 

(8)               there is no continuing Event of Default in respect of the Notes.

 

(b)               Upon effectiveness of the substitution, the Substituted Issuer and the Issuer shall deliver to the Trustee an Officer’s Certificate, executed by an authorized officer, certifying that the terms of this section have been complied with and attaching copies of all documents contemplated herein.

 

(c)               Upon the execution of the Issuer Substitution Documents as referred to in paragraph (a)(1) above and compliance with the other conditions in paragraph (a), (1) the Substituted Issuer shall be deemed to be named in the Notes as the principal debtor in place of the Issuer (or of any previous substitute under these provisions), (2) the Additional Guarantor shall be deemed to be named as a guarantor of the Notes and (3) the Notes shall thereupon be deemed to be amended to give effect to the transactions referred to in (1) and (2). Except as set forth above, the execution of the Issuer Substitution Documents shall operate to release the Issuer (or such previous substitute as aforesaid) from all its obligations as issuer of the Notes.

 

(d)               Not later than 10 Business Days after the execution of the Issuer Substitution Documents, the Substituted Issuer shall give notice thereof to the Holders of the Notes in accordance with the provisions described under Section 1.6.

 

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Article XIV

 

GUARANTEES

 

Section 14.1.      Guarantees.

 

Nexa CJM, Nexa Peru and Nexa Brazil hereby, jointly, severally, fully, absolutely and unconditionally guarantee on an unsecured basis to each Holder of a Note authenticated and delivered by the Trustee, and to the Trustee on behalf of such Holder, and for itself and the Paying Agents, the due and punctual payment of the principal of (and premium, if any) and interest (including any Additional Amounts) on such Note and all other obligations of the Issuer under this Indenture, when and as the same shall become due and payable, whether at the Stated Maturity or by acceleration, redemption, purchase or otherwise, in accordance with the terms of such Note and of this Indenture. In case of the failure of the Issuer punctually to make any such payment, each of the Guarantors hereby agrees to cause such payment to be made punctually when and as the same shall become due and payable, whether at the Stated Maturity or by acceleration, call for redemption, purchase or otherwise, and as if such payment were made by the Issuer.

 

The Guarantees constitute unconditional and unsubordinated obligations of each of the Guarantors that will at all times rank at least equally with all other present and future unsecured senior obligations of each such Guarantor, except for any obligations that may be preferred by provisions of law that are both mandatory and of general application.

 

Each of the Guarantors hereby agrees that its obligations hereunder shall be unconditional, irrespective of the validity, regularity or enforceability of any Note or this Indenture, the absence of any action to enforce the same, any release or amendment or waiver of any term of any other guarantee of, or any consent to depart from any requirement of any other guarantee, of all or any of the Notes, any waiver or consent by the Holder of any Note or by the Trustee with respect to any provisions thereof or of this Indenture, the obtaining of any judgment against the Issuer or any action to enforce the same or any other circumstances which might otherwise constitute a legal or equitable discharge or defense of a guarantor. Each of the Guarantors hereby waives notice of the acceptance of its Guarantee and of any of the obligations under this Indenture or the Notes (the “Obligations”) or of the accrual thereof, and further waives presentment, protest, notice or demand. This is a continuing guarantee and is a guarantee of payment and not of collection, and each of the Guarantors waives any right to require the Holders to initiate collection proceeds or otherwise enforce payment of the Obligations or any security or other guarantee therefore before obtaining payment hereunder.

 

The Guarantees shall continue to be in effect or be reinstated, as the case may be, if at any time (i) any payment in respect of any of the Obligations is rescinded or must otherwise be returned by the Holders, whether by reason of the insolvency, bankruptcy, receivership, reorganization or liquidation of the Issuer or any Guarantor or any other obligor or otherwise, all as though such payment had not been made or (ii) a Substituted Issuer, as defined in Section 13.1, assumes the Issuer’s obligations under the Notes pursuant to Article XIII hereof.

 

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Each of the Guarantors hereby waives the benefits of diligence, presentment, demand of payment, any requirement that the Trustee or any of the Holders protect, secure, perfect or insure any security interest in or other Lien on any property subject thereto or exhaust any right or take any action against the Issuer or any other Person or any collateral, filing of claims with a court in the event of insolvency or bankruptcy of the Issuer, any right to require a proceeding first against the Issuer, protest or notice with respect to any Note or the indebtedness evidenced thereby and all demands whatsoever, and covenants, that these Guarantees will be discharged in respect of any Note except by complete performance of the obligations contained in such Note and in the Guarantees. Each of the Guarantors hereby agrees that, in the event of a default in payment of principal (or premium, if any) or interest on any Note, whether at its Stated Maturity or by acceleration, redemption, purchase or otherwise, legal proceedings may be instituted by the Trustee on behalf of, or by, the Holder of such Note, subject to the terms and conditions set forth in this indenture, directly against any or all of the Guarantors to enforce the Guarantees without first proceeding against the Issuer. Each of the Guarantors agrees that if, after the occurrence and during the continuance of an Event of Default, the Trustee or any of the Holders are prevented by applicable law from exercising their respective rights to accelerate the maturity of the Notes, to collect interest on the Notes or to enforce or exercise any other right or remedy with respect to the Notes, or the Trustee or the Holders are prevented from taking any action to realize on any collateral, each of the Guarantor agrees to pay to the Trustee for the account of the Holders, upon demand therefore, the amount that would otherwise have been due and payable had such rights and remedies been permitted to be exercised by the Trustee or any of the Holders.

 

No provision of the Guarantees, Notes or of this Indenture shall alter or impair the Guarantees of the Guarantors, of which the Guarantees are absolute and unconditional, of the due and punctual payment of the principal (and premium, if any) and interest (and Additional Amounts, if any) on the Note and the obligation under this Indenture upon which each Guarantee is endorsed.

 

Each of the Guarantors shall be subrogated to all rights of the Holders of the Notes upon which its Guarantee is endorsed against the Issuer in respect of any amounts paid by each of the Guarantors on account of such Note pursuant to the provisions of the Guarantees or this Indenture; provided, however, that none of the Guarantors shall be entitled to enforce or to receive any payments arising out of, or based upon, such right of subrogation until the principal of (and premium, if any) and interest (and Additional Amounts, if any) on all Notes issued hereunder shall have been paid in full.

 

The Guarantees shall remain in full force and effect and continue to be effective should any petition be filed by or against the Issuer for liquidation or reorganization, should the Issuer become insolvent or make an assignment for the benefit of creditors or should a receiver or trustee be appointed for all or any significant part of the Issuer’s assets, and shall, to the fullest extent permitted by law, continue to be effective or be reinstated, as the case may be, if at any time payment and performance of the obligations under the Notes is, pursuant to applicable law, rescinded or reduced in amount, or must otherwise be restored or returned by any obligee on the Notes, whether as a “voidable preference,” “fraudulent transfer” or otherwise, all as though such payment or performance had not been made. In the event that any payment, or any part thereof, is rescinded, reduced, restored or returned, the Notes shall, to the fullest extent permitted by law, be reinstated and deemed reduced only by such amount paid and not so rescinded, reduced, restored or returned.

 

Each of the Guarantors hereby irrevocably waives all benefits set forth in the following provisions of the Brazilian law: articles 333, sole paragraph, 366, 368, 827, 829, sole paragraph, 830, 834, 835, 837 and 838 of the Brazilian Civil Code and articles 130 and 794 of the Brazilian Civil Procedure Code.

 

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No stockholder, officer, director, employer or incorporator, past, present or future, of any Guarantor, as such, shall have any personal liability under the Guarantee by reason of his, her or its status as such stockholder, officer, director, employer or incorporator.

 

Section 14.2.      Delivery of the Guarantee.

 

The delivery of any Note by the Trustee, after the authentication thereof hereunder, shall constitute due delivery of the Guarantees set forth herein on behalf of the Guarantors.

 

Section 14.3.      Release of Guarantor.

 

(a)               Concurrently with any consolidation or merger of any of the Guarantors or any sale or conveyance of the property of any of the Guarantors as an entirety or substantially as an entirety, in each case as permitted by Section 9.1(a) hereof, and upon delivery by such Guarantor to the Trustee of an Officer’s Certificate and an Opinion of Counsel to the effect that such consolidation, merger, sale or conveyance was made in accordance with Section 9.1(a) hereof, the Trustee shall execute any documents reasonably required in order to evidence the release of such Guarantor from its obligations under its Guarantee endorsed on the Notes and under this Article XIV.

 

(b)               Concurrently with the defeasance of the Notes under Section 12.2 hereof or the covenant defeasance of the Notes under Section 12.3 hereof, each of the Guarantors shall be released from all of its obligations under its Guarantee endorsed on the Notes and under this Article XIV.

 

Article XV

MEETINGS OF HOLDERS OF SECURITIES

 

Section 15.1.      Purposes for Which Meetings May Be Called.

 

A meeting of Holders of Notes may be called at any time and from time to time pursuant to this Article to consider any matter affecting their interests, including, if proposed by the Issuer, the modification of the terms and conditions of the Notes; provided that any modification postponing the date for payment of any interest, reducing or canceling any amount of principal or the rate of interest payable or altering the currency of payment in respect of the Notes will only be binding if passed at a meeting of Holders at which a special quorum (as set forth in Section 15.4) is present.

 

Section 15.2.      Call, Notice and Place of Meetings.

 

(1)               The Trustee may at any time call a meeting of Holders of Notes of any series for any purpose specified in Section 15.1, to be held at such time and at such place in the Borough of Manhattan, The City of New York as the Trustee shall determine. Notice of every meeting of Holders of Notes, setting forth the time and the place of such meeting and in general terms the action proposed to be taken at such meeting, shall be given, in the manner provided in Section 1.6, not less than 21 nor more than 180 days prior to the date fixed for the meeting.

 

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(2)               In case at any time the Issuer, pursuant to a Board Resolution, or the Holders of at least 10% in principal amount of the Outstanding Notes shall have requested the Trustee to call a meeting of the Holders of Notes for any purpose specified in Section 15.1, by written request setting forth in reasonable detail the action proposed to be taken at the meeting, and the Trustee shall not have made the first publication of the notice of such meeting within 21 days after receipt of such request or shall not thereafter proceed to cause the meeting to be held as provided herein, then the Issuer or the Holders of Notes in the amount specified above, as the case may be, may determine the time and the place in the Borough of Manhattan, The City of New York for such meeting and may call such meeting for such purposes by giving notice thereof as provided in subsection (1) of this Section.

 

Section 15.3.      Persons Entitled to Vote at Meetings.

 

To be entitled to vote at any meeting of Holders of Notes, a Person shall be (i) a Holder on a record date established pursuant to Section 15.5 of one or more Outstanding Notes, or (ii) a Person appointed by an instrument in writing as proxy for a Holder or Holders of one or more Outstanding Notes by such Holder or Holders. The only Persons who shall be permitted to be present or to speak at any meeting of Holders of Notes of any series shall be the Persons entitled to vote at such meeting and their counsel, any representatives of the Trustee and its counsel and any representatives of the Issuer and its counsel.

 

Section 15.4.      Quorum; Action.

 

The Persons entitled to vote a majority in principal amount of the Outstanding Notes shall constitute a “quorum” for a meeting of Holders of Notes, however, any modification postponing the date for payment of any interest, reducing or canceling any amount of principal or the rate of interest payable or altering the currency of payment in respect of the Notes will only be binding if passed at a meeting of Holders of at least 66 2/3% of the Notes (a “special quorum”). In the absence of a quorum or a special quorum, as the case may be, within 15 minutes (or such longer period not exceeding 30 minutes as the chairman may decide) of the time appointed for any such meeting, the meeting shall if convened upon the requisition of Holders be dissolved. In any other case it shall stand adjourned to the same day in the next week (or if such day is not a Business Day the next succeeding Business Day) at the same time and place. If within 15 minutes (or such longer period not exceeding 30 minutes as the chairman may decide) after the time appointed for any adjourned meeting a quorum or a special quorum, as the case may be, is not present for the transaction of any particular business, then, subject and without prejudice to the transaction of the business (if any) for which a quorum or a special quorum, as the case may be, is present, the chairman may either (with the approval of the Trustee) dissolve such meeting or adjourn the same for such period, being not less than ten calendar days (but without any maximum number of calendar days), and to such place as may be appointed by the chairman either at or subsequent to such adjourned meeting and approved by the Trustee, and the provisions of this sentence shall apply to all further adjourned such meetings.

 

Notice of the reconvening of any adjourned meeting shall be given as provided in Section 15.2(1), except that such notice need be given only once not less than five days prior to the date on which the meeting is scheduled to be reconvened. Notice of a reconvening of an adjourned meeting shall state expressly the percentage, as provided above, of the principal amount of the Outstanding Notes of such series which shall constitute a quorum.

 

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Any resolution passed or decision taken at any meeting of Holders of Notes of any series duly held in accordance with this Section shall be binding on all the Holders of Notes of such series, whether or not presented or represented at the meeting. However, for the avoidance of doubt, no actions taken at such meeting shall be binding on all Holders of Notes unless such actions were approved by the minimum percentage in principal amount of the Outstanding Notes of the series as required elsewhere in this Indenture with respect to such actions.

 

Section 15.5.      Determination of Voting Rights; Conduct and Adjournment of Meetings.

 

(a)               Notwithstanding any other provisions of this Indenture, the Trustee may make such reasonable regulations as it may deem advisable for any meeting of Holders of Notes of a series in regard to proof of the holding of Notes of such series and the appointment of proxies and in regard to the appointment and duties of inspectors of votes, the submission and examination of proxies, certificates and other evidence of the right to vote, and such other matters concerning the conduct of the meeting as it shall deem appropriate. Except as otherwise permitted or required by any such regulations, the holding of Notes shall be proved in the manner specified in Section 1.4 and the appointment of any proxy shall be proved in the manner specified in Section 1.4. Such regulations may provide that written instruments appointing proxies, regular on their face, may be presumed valid and genuine without the proof specified in Section 1.4 or other proof.

 

(b)               The Trustee shall, by an instrument in writing, appoint a temporary chairman of the meeting, unless the meeting shall have been called by the Issuer or by Holders of Notes as provided in Section 15.2(2), in which case the Issuer or the Holders of Notes of the series calling the meeting, as the case may be, shall in like manner appoint a temporary chairman. A permanent chairman and a permanent secretary of the meeting shall be elected by vote of the Persons entitled to vote a majority in principal amount of the Outstanding Notes of such series represented at the meeting.

 

(c)               At any meeting each Holder of a Note of such series or proxy shall be entitled to one vote for each $1,000 principal amount of the Outstanding Notes of such series held or represented by him or her; provided, however, that no vote shall be cast or counted at any meeting in respect of any Note challenged as not Outstanding and ruled by the chairman of the meeting to be not Outstanding. The chairman of the meeting shall have no right to vote, except as a Holder of a Note of such series or proxy.

 

(d)               Any meeting of Holders of Notes of any series duly called pursuant to Section 15.2 at which a quorum is present may be adjourned from time to time by Persons entitled to vote a majority in principal amount of the Outstanding Notes of such series represented at the meeting, and the meeting may be held as so adjourned without further notice.

 

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Section 15.6.      Counting Votes and Recording Action of Meetings.

 

The vote upon any resolution submitted to any meeting of Holders of Notes of any series shall be by written ballots on which shall be subscribed the signatures of the Holders of Notes of such series or of their representatives by proxy and the principal amounts and serial numbers of the Outstanding Notes of such series held or represented by them. The permanent chairman of the meeting shall appoint two inspectors of votes who shall count all votes cast at the meeting for or against any resolution and who shall make and file with the secretary of the meeting their verified written reports in duplicate of all votes cast at the meeting. A record, at least in duplicate, of the proceedings of each meeting of Holders of Notes of any series shall be prepared by the secretary of the meeting and there shall be attached to said record the original reports of the inspectors of votes on any vote by ballot taken thereat and affidavits by one or more persons having knowledge of the facts setting forth a copy of the notice of the meeting and showing that said notice was given as provided in Section 15.2 and, if applicable, Section 15.5. Each copy shall be signed and verified by the affidavits of the permanent chairman and secretary of the meeting and one such copy shall be delivered to the Issuer, and another to the Trustee to be preserved by the Trustee, the latter to have attached thereto the ballots voted at the meeting. Any record so signed and verified shall be conclusive evidence of the matters therein stated.

 

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IN WITNESS WHEREOF, the parties hereto have caused this Indenture to be duly executed as of the day and year first above written.

 

  NEXA RESOURCES S.A.
   
  By:  
    Name:
    Title:
   
  By:  
    Name:
    Title:
   

 

Signature Page to Indenture

 

 

 

IN WITNESS WHEREOF, the parties hereto have caused this Indenture to be duly executed as of the day and year first above written.

 

  NEXA RESOURCES CAJAMARQUILLA S.A.
   
  By:  
    Name:
    Title:
   
  By:  
    Name:
    Title:
   

 

Signature Page to Indenture

 

 

 

IN WITNESS WHEREOF, the parties hereto have caused this Indenture to be duly executed as of the day and year first above written.

 

  NEXA RESOURCES PERU S.A.A.
   
  By:  
    Name:
    Title:
   
  By:  
    Name:
    Title:
   

 

Signature Page to Indenture

 

 

 

IN WITNESS WHEREOF, the parties hereto have caused this Indenture to be duly executed as of the day and year first above written.

 

  NEXA RECURSOS MINERAIS S.A.
   
  By:  
    Name:
    Title:
   
  By:  
    Name:
    Title:
   

 

Witnesses:  
   
By: /s/ Felipe Da Silva Azevedo  
  Name: Felipe Da Silva Azevedo  
     
By: /s/ Junia Fontes Vieira Cidade  
  Name: Junia Fontes Vieira Cidade  

 

Signature Page to Indenture

 

 

 

  THE BANK OF NEW YORK MELLON,
as Trustee, Principal Paying Agent, Transfer Agent and Registrar
   
  By:  
    Name:
    Title:

 

Signature Page to Indenture

 

 

 

 

EXHIBIT A

 

FORM OF CERTIFICATION FOR TRANSFER OR EXCHANGE OF
RESTRICTED GLOBAL NOTE TO REGULATION S GLOBAL
NOTE
(Exchanges or transfers pursuant to
Section 3.4(c)(2) of the Indenture)

 

The Bank of New York Mellon
240 Greenwich Street
New York, New York 10286
United States
Attention: Global Corporate Trust

 

Re: Nexa Resources S.A.
6.500% Notes due 2028 (the “Notes”)

 

Reference is hereby made to the Indenture, dated as of June 18, 2020 (the “Indenture”), among Nexa Resources S.A., as Issuer, Nexa Resources Cajamarquilla S.A., Nexa Resources Perú S.A.A. and Nexa Recursos Minerais S.A., as Guarantors, and The Bank of New York Mellon, a New York banking corporation, as trustee (the “Trustee”), as principal paying agent (the “Principal Paying Agent”), as transfer agent (the “Transfer Agent”) and registrar (the “Security Registrar”). Capitalized terms used but not defined herein shall have the meanings given to them in the Indenture.

 

This letter relates to U.S.$[                         ] aggregate principal amount of Notes which are held in the form of the Restricted Global Note (CUSIP No. 65290D AA1 / ISIN No. US65290DAA19 / Common Code 219373309) with the Depositary in the name of [insert name of transferor] (the “Transferor”). The Transferor has requested a transfer of such beneficial interest in the Notes to a Person who will take delivery thereof in the form of an equal aggregate principal amount of Notes evidenced by the Regulation S Global Note (CUSIP No. L67359 AA4 / ISIN No. USL67359AA48 / Common Code 219373368).

 

In connection with such request, and in respect of such Notes, the Transferor does hereby certify that such transfer has been effected in accordance with the transfer restrictions set forth in the Notes and that:

 

(A) The offer of the Notes was not made to a person in the United States; and

 

(B) either:

 

(i) at the time the buy order was originated, the transferee was outside the United States or the Transferor and any person acting on its behalf reasonably believed that the transferee was outside the United States; or

 

(ii) the transaction was executed in, on or through the facilities of a designated offshore securities market and neither the Transferor nor any person acting on our behalf knows that the transaction was pre-arranged with a buyer in the United States;

 

(C) no directed selling efforts have been made in contravention of the requirements of Rule 903(a)(2) or 904(a)(2) of Regulation S, as applicable; and

 

(D) the transaction is not part of a plan or scheme to evade the registration requirements of the Securities Act.

 

We understand that this certificate is required in connection with certain securities laws of the United States. In connection therewith, if administrative or legal proceedings are commenced or threatened in connection with which this certificate is or would be relevant, we irrevocably authorize you to produce this certificate to any interested party in such proceeding. This certificate and the statements contained herein are made for your benefit and the benefit of the Issuer and the Guarantors.

 

  [INSERT NAME OF TRANSFEROR]
   
   
  By:                  
    Name:
    Title:
     
Dated:      

 

cc: Nexa Resources S.A.

 

 

 

 

EXHIBIT B

 

FORM OF CERTIFICATION FOR TRANSFER OR EXCHANGE OF
REGULATION S GLOBAL NOTE TO RESTRICTED GLOBAL
NOTE
(Exchanges or transfers pursuant to
Section 3,4(c)(3) of the Indenture)

 

The Bank of New York Mellon
240 Greenwich Street
New York, New York 10286
United States
Attention: Global Corporate Trust

 

Re: Nexa Resources S.A.
6.500% Notes due 2028 (the “Notes”)

 

Reference is hereby made to the Indenture, dated as of June 18, 2020 (the “Indenture”), among Nexa Resources S.A., as Issuer, Nexa Resources Cajamarquilla S.A., Nexa Resources Perú S.A.A. and Nexa Recursos Minerais S.A., as Guarantors, and The Bank of New York Mellon, a New York banking corporation, as trustee (the “Trustee”), as principal paying agent (the “Principal Paying Agent”), as transfer agent (the “Transfer Agent”) and registrar (the “Security Registrar”). Capitalized terms used but not defined herein shall have the meanings given to them in the Indenture.

 

This letter relates to U.S.$[                       ] principal amount of Notes which are evidenced by an aggregate Regulation S Global Note (CUSIP No. L67359 AA4 / ISIN No. USL67359AA48 / Common Code 219373368) and held with the Depositary through [Euroclear] [Clearstream] in the name of [insert name of transferor] (the “Transferor”). The Transferor has requested a transfer of such beneficial interest in Notes to a person that will take delivery thereof in the form of an equal principal amount of Notes evidenced by a Restricted Global Note of the same series and of like tenor as the Notes (CUSIP No. 65290D AA1 / ISIN No. US65290DAA19 / Common Code 219373309).

 

In connection with such request and in respect of such Notes, the Transferor does hereby certify that such transfer is being effected pursuant to and in accordance with Rule 144A under the Securities Act and, accordingly, the Transferor does hereby further certify that the Notes are being transferred to a Person that the Transferor reasonably believes is purchasing the Notes for its own account, or for one or more accounts with respect to which such person exercises sole investment discretion, and such person and each such account is a “qualified institutional buyer” within the meaning of Rule 144A, in each case in a transaction meeting the requirements of Rule 144A and in accordance with any applicable securities laws of any state of the United States.

 

This certificate and the statements contained herein are made for your benefit and the benefit of the Issuer and the Guarantors.

 

    [INSERT NAME OF TRANSFEROR]
     
     
    By:                      
      Name:
      Title:
       
Dated:      

 

cc: Nexa Resources S.A.

 

 

 

 

EXHIBIT C-1

 

FORM OF CERTIFICATION FOR TRANSFER
OR EXCHANGE OF NON-GLOBAL RESTRICTED NOTE TO
RESTRICTED GLOBAL NOTE
(Transfers and exchanges pursuant to
Section 3.4(c)(4) of the Indenture)

 

The Bank of New York Mellon
240 Greenwich Street
New York, New York 10286
United States
Attention: Global Corporate Trust

 

Re: Nexa Resources S.A.
6.500% Notes due 2028 (the “Notes”)

 

Reference is hereby made to the Indenture, dated as of June 18, 2020 (the “Indenture”), among Nexa Resources S.A., as Issuer, Nexa Resources Cajamarquilla S.A., Nexa Resources Perú S.A.A. and Nexa Recursos Minerais S.A., as Guarantors, and The Bank of New York Mellon, a New York banking corporation, as trustee (the “Trustee”), as principal paying agent (the “Principal Paying Agent”), as transfer agent (the “Transfer Agent”) and registrar (the “Security Registrar”). Capitalized terms used but not defined herein shall have the meanings given to them in the Indenture.

 

This letter relates to U.S.$[                      ] principal amount of Restricted Notes held in definitive form (CUSIP No. 65290D AA1 / ISIN No. US65290DAA19 / Common Code 219373309) by [insert name of transferor] (the “Transferor”). The Transferor has requested an exchange or transfer of such Notes.

 

In connection with such request and in respect of such Notes, the Transferor does hereby certify that (i) such Notes are owned by the Transferor and are being exchanged without transfer or (ii) such transfer has been effected pursuant to and in accordance with Rule 144A or Rule 144 under the United States Securities Act of 1933, as amended (the “Securities Act”) and accordingly the Transferor does hereby further certify that:

 

(A) the Notes are being transferred to a person that the Transferor reasonably believes is purchasing the Notes for its own account, or for one or more accounts with respect to which such Person exercises sole investment discretion;

 

(B) such Person and each such account is a “qualified institutional buyer” within the meaning of Rule 144A; and

 

(C) the Notes have been transferred in a transaction meeting the requirements of Rule 144A and in accordance with any applicable securities laws of any state of the United States.

 

We understand that this certificate is required in connection with certain securities laws of the United States. In connection therewith, if administrative or legal proceedings are commenced or threatened in connection with which this certificate is or would be relevant, we irrevocably authorize you to produce this certificate to any interested party in such proceeding. This certificate and the statements contained herein are made for your benefit and the benefit of the Issuer and the Guarantors.

 

    [INSERT NAME OF TRANSFEROR]
       
       
    By:                     
      Name:
    Title:
       
Dated:      

 

cc: Nexa Resources S.A.

 

 

 

 

EXHIBIT C-2

 

FORM OF CERTIFICATION FOR TRANSFER
OR EXCHANGE OF NON-GLOBAL RESTRICTED NOTE TO
REGULATION S GLOBAL NOTE
(Transfers and exchanges pursuant to
Section 3.4(c)(4) of the Indenture)

 

The Bank of New York Mellon
240 Greenwich Street
New York, New York 10286
United States
Attention: Global Corporate Trust

 

Re: Nexa Resources S.A.
6.500% Notes due 2028 (the “Notes”)

 

Reference is hereby made to the Indenture, dated as of June 18, 2020 (the “Indenture”), among Nexa Resources S.A., as Issuer, Nexa Resources Cajamarquilla S.A., Nexa Resources Perú S.A.A. and Nexa Recursos Minerais S.A., as Guarantors, and The Bank of New York Mellon, a New York banking corporation, as trustee (the “Trustee”), as principal paying agent (the “Principal Paying Agent”), as transfer agent (the “Transfer Agent”) and registrar (the “Security Registrar”). Capitalized terms used but not defined herein shall have the meanings given to them in the Indenture.

 

This Letter relates to U.S.$[                        ] principal amount of Restricted Notes held in definitive form (CUSIP No. 65290D AA1 / ISIN No. US65290DAA19 / Common Code 219373309) by [insert name of transferor] (the “Transferor”). The Transferor has requested an exchange or transfer of such Notes.

 

In connection with such request and in respect of such Notes, the Transferor does hereby certify that (i) such Notes are owned by the Transferor and are being exchanged without transfer or (ii) such transfer has been effected pursuant to and in accordance with (a) Rule 903 or Rule 904 under the Securities Act of 1933, as amended (the “Act”), or (b) Rule 144 under the Act, and accordingly the Transferor does hereby further certify that:

 

(A) the offer of the Notes was not made to a person in the United States; (B) either:

 

(i) at the time the buy order was originated, the transferee was outside the United States or the Transferor and any person acting on its behalf reasonably believed that the transferee was outside the United States, or

 

(ii) the transaction was executed in, on or through the facilities of a designated offshore securities market and neither the Transferor nor any person acting on its behalf knows that the transaction was pre-arranged with a buyer in the United States;

 

(C) no directed selling efforts have been made in contravention of the requirements of Rule 903(a)(2) or 904(b)(2)) of Regulation S, as applicable; and

 

(D) the transaction is not part of a plan or scheme to evade the registration requirements of the Act.

 

We understand that this certificate is required in connection with certain securities laws of the United States. In connection therewith, if administrative or legal proceedings are commenced or threatened in connection with which this certificate is or would be relevant, we irrevocably authorize you to produce this certificate to any interested party in such proceeding. This certificate and the statements contained herein are made for your benefit and the benefit of the Issuer and the Guarantors.

 

    [INSERT NAME OF TRANSFEROR]
     
     
    By:                     
      Name:
      Title:
       
Dated:      

 

cc: Nexa Resources S.A.

 

 

 

 

EXHIBIT D-l

 

FORM OF CERTIFICATION FOR TRANSFER
OR EXCHANGE OF NON-GLOBAL REGULATION S
NOTE TO RESTRICTED GLOBAL NOTE
(Transfers and exchanges pursuant to
Section 3.4(c)(5) of the Indenture)

 

The Bank of New York Mellon
240 Greenwich Street
New York, New York 10286
United States
Attention: Global Corporate Trust

 

Re: Nexa Resources S.A.
6.500% Notes due 2028 (the “Notes”)

 

Reference is hereby made to the Indenture, dated as of June 18, 2020 (the “Indenture”), among Nexa Resources S.A., as Issuer, Nexa Resources Cajamarquilla S.A., Nexa Resources Perú S.A.A. and Nexa Recursos Minerais S.A., as Guarantors, and The Bank of New York Mellon, a New York banking corporation, as trustee (the “Trustee”), as principal paying agent (the “Principal Paying Agent”), as transfer agent (the “Transfer Agent”) and registrar (the “Security Registrar”). Capitalized terms used but not defined herein shall have the meanings given to them in the Indenture.

 

This letter relates to U.S.$[                         ] principal amount of Regulation S Global Notes held in definitive form (CUSIP No. L67359 AA4 / ISIN No. USL67359AA48 / Common Code 219373368) by [insert name of transferor] (the “Transferor”). The Transferor has requested an exchange or transfer of such Notes.

 

In connection with such request and in respect of such Notes, the Transferor does hereby certify that (i) such Notes are owned by the Transferor and are being exchanged without transfer or (ii) such transfer has been effected pursuant to and in accordance with Rule 144A under the United States Securities Act of 1933, as amended, and accordingly the Transferor does hereby further certify that the Notes are being transferred to a person that the Transferor reasonably believes is purchasing the Notes for its own account, or for one or more accounts with respect to which such Person exercises sole investment discretion, and such Person and each such account is a “qualified institutional buyer” within the meaning of Rule 144A, in each case in a transaction meeting the requirements of Rule 144A and in accordance with any applicable securities laws of any state of the United States.

 

We understand that this certificate is required in connection with certain securities laws of the United States. In connection therewith, if administrative or legal proceedings are commenced or threatened in connection with which this certificate is or would be relevant, we irrevocably authorize you to produce this certificate to any interested party in such proceeding. This certificate and the statements contained herein are made for your benefit and the benefit of the Issuer and the Guarantors.

 

    [INSERT NAME OF TRANSFEROR]
       
       
    By:                     
      Name:
      Title:
       
Dated:      

 

cc: Nexa Resources S.A.

 

 

 

 

EXHIBIT D-2

 

FORM OF CERTIFICATION FOR TRANSFER
OR EXCHANGE OF NON-GLOBAL REGULATION S
NOTE TO REGULATION S GLOBAL NOTE
(Transfers and exchanges pursuant to
Section 3.4(c)(5) of the Indenture)

 

The Bank of New York Mellon
240 Greenwich Street
New York, New York 10286
United States
Attention: Global Corporate Trust

 

Re: Nexa Resources S.A.
6.500% Notes due 2028 (the “Notes”)

 

Reference is hereby made to the Indenture, dated as of June 18, 2020 (the “Indenture”), among Nexa Resources S.A., as Issuer, Nexa Resources Cajamarquilla S.A., Nexa Resources Perú S.A.A. and Nexa Recursos Minerais S.A., as Guarantors, and The Bank of New York Mellon, a New York banking corporation, as trustee (the “Trustee”), as principal paying agent (the “Principal Paying Agent”), as transfer agent (the “Transfer Agent”) and registrar (the “Security Registrar”). Capitalized terms used but not defined herein shall have the meanings given to them in the Indenture.

 

This letter relates to U.S.$[                         ] principal amount of Regulation S Global Notes held in definitive form (CUSIP No. L67359 AA4 / ISIN No. USL67359AA48 / Common Code 219373368) by [insert name of transferor] (the “Transferor”). The Transferor has requested an exchange or transfer of such Notes.

 

In connection with such request and in respect of such Notes, the Transferor does hereby certify that (i) such Notes are owned by the Transferor and are being exchanged without transfer or (ii) such transfer has been effected pursuant to and in accordance with (a) Rule 903 or Rule 904 under the Securities Act of 1933, as amended (the “Act”), or (b) Rule 144 under the Act, and accordingly the Transferor does hereby further certify that:

 

(A) the offer of the Notes was not made to a person in the United States; (B) either:

 

(i) at the time the buy order was originated, the transferee was outside the United States or the Transferor and any person acting on its behalf reasonably believed that the transferee was outside the United States, or

 

(ii) the transaction was executed in, on or through the facilities of a designated offshore securities market and neither the Transferor nor any person acting on its behalf knows that the transaction was pre-arranged with a buyer in the United States;

 

(C) no directed selling efforts have been made in contravention of the requirements of Rule 903(a)(2) or 904(b)(2) of Regulation S, as applicable; and

 

(D) the transaction is not pan of a plan or scheme to evade the registration requirements of the Act.

 

We understand that this certificate is required in connection with certain securities laws of the United States. In connection therewith, if administrative or legal proceedings are commenced or threatened in connection with which this certificate is or would be relevant, we irrevocably authorize you to produce this certificate to any interested party in such proceeding. This certificate and the statements contained herein are made for your benefit and the benefit of the Issuer and the Guarantors.

 

    [INSERT NAME OF TRANSFEROR]
       
       
    By:                  
      Name:
      Title:
       
Dated:      

 

cc: Nexa Resources S.A.

 

 

 

Exhibit 2.4

 

DESCRIPTION OF THE REGISTRANT’S SECURITIES REGISTERED PURSUANT TO SECTION 12 OF THE SECURITIES EXCHANGE ACT OF 1934

 

As of December 31, 2020, Nexa Resources S.A. (“Nexa Resources,” “we,” “us,” and “our”) had one class of securities registered under Section 12 of the Securities Exchange Act of 1934, as amended: our common shares.

 

Description of Common Shares

 

The following description of our common shares is a summary and does not purport to be complete. It is subject to and qualified in its entirety by reference to our amended and restated articles of association, which is incorporated as an exhibit to our most recent Annual Report on Form 20-F, the Luxembourg law of August 10, 1915 on commercial companies, as amended (the “1915 Law”), and by any other applicable Luxembourg corporate law. We encourage you to read our articles of association, the 1915 Law, and applicable provisions of Luxembourg law for additional information.

 

Share capital

 

As of December 31, 2020, our issued share capital was US$132,438,611 represented by 132,438,611 common shares fully paid, with par value of US$1.00 per share. In addition to our issued share capital, we have an authorized share capital of US$231,924,819, represented by 231,924,819 common shares. Our common shares are publicly traded in the United States on the New York Stock Exchange (or NYSE), under the ticker symbol NEXA. Our common shares also trade on the Toronto Stock Exchange (or TSX), under the ticker symbol NEXA.

 

Changes to our share capital are decided by our shareholders or, pursuant to our articles of association, by our board of directors within the limits of the authorized share capital. Our shareholders may at any time at a shareholders’ meeting decide to increase or decrease our share capital. Such resolution must satisfy the quorum and majority requirements that apply to an amendment of the articles of association, as described below. No shareholder is liable to make any further contribution to our share capital other than with respect to shares held by such shareholder that are not fully paid-up.

 

Distributions

 

Pursuant to our articles of association, the general meeting of shareholders may approve dividends and the board of directors may declare interim dividends, in each case to the extent permitted by Luxembourg law. Under Luxembourg law, dividends are determined by a simple majority vote at a general shareholders’ meeting based on the recommendation of our board of directors. Pursuant to our articles of association, the board of directors may also declare distributions to our shareholders in the form of reimbursement of share premium or interim dividends to the extent permitted by Luxembourg law.

 

Each common share entitles the holder to participate equally in any distributions, if and when declared by the general meeting of shareholders or, in the case of interim dividends or reimbursements of share premium, the board of directors, out of funds legally available for such purposes. Dividends and other distributions on our common shares will be declared and paid in U.S. dollars. Dividends and other distributions on common shares listed on the NYSE will be the same as for common shares listed on the TSX. Declared and unpaid distributions held by us for the account of the shareholders shall not bear interest. Under Luxembourg law, claims for unpaid distributions will lapse in our favor five years after the date such distribution has been declared.

 

We and our subsidiaries are subject to certain legal requirements that may affect our ability to pay dividends or other distributions. Distributions to shareholders (including in the form of dividends or reimbursement of share premium) may only be made from amounts available for distribution in accordance with Luxembourg law, determined based on our standalone statutory accounts prepared under Luxembourg GAAP. Under Luxembourg law, the amount of a distribution paid to shareholders (including in the form of dividends or reimbursement of share premium) may not exceed the amount of the profits at the end of the last financial year plus any profits carried forward and any amounts drawn from reserves that are available for that purpose, less any losses carried forward and sums to be placed in reserve in accordance with Luxembourg law or our articles of association. Furthermore, no distributions (including in the form of dividends or reimbursement of share premium) may be made if at the end of the last financial year the net assets as set out in the standalone statutory accounts prepared under Luxembourg GAAP are, or following such a distribution would become, less than the amount of the subscribed share capital plus the non-distributable reserves. Distributions in the form of dividends may only be made from net profits and profits carried forward, whereas distributions in the form of share premium reimbursements may only be made from available share premium.

 

 

Luxembourg law also requires at least 5.0% of our net profits per year to be allocated to the creation of a legal reserve until such reserve has reached an amount equal to 10.0% of our issued share capital. If the legal reserve subsequently falls below the 10.0% threshold, at least 5.0% of net profits again must be allocated toward the reserve. The legal reserve is not available for distribution.

 

Voting rights

 

There are no restrictions on the rights of Luxembourg or non-Luxembourg residents to vote our shares. All of our shareholders, including our public shareholders, hold common shares with identical voting rights, preferences and privileges. Each common share entitles the shareholder to attend a general meeting of shareholders in person or by proxy, to address the general meeting of shareholders and to vote. Each common share entitles the holder to one vote at the general meeting of shareholders.

 

General meeting of shareholders

 

In accordance with Luxembourg law and our articles of association, any regularly constituted general meeting of our shareholders has the power to order, carry out or ratify acts relating to our operations to the extent that such decisions are the domain of the shareholders and not the board of directors.

 

Our annual general meeting of shareholders shall be held at our registered office, or at such other place in Luxembourg as may be specified in the notice of the meeting, within six months after the end of the relevant financial year. Except as otherwise specified in our articles of association, resolutions at a general meeting of shareholders are adopted by a simple majority of shares present or represented and voting at such meeting.

 

A shareholder entitled to vote may act at any general meeting of shareholders by appointing another person (who need not be a shareholder) as his proxy, which proxy shall be in writing and comply with such requirements as determined by our board with respect to the attendance to the general meeting, and proxy forms in order to enable shareholders to exercise their right to vote. All proxies must be received by us (or our agents) no later than the day determined by our board of directors.

 

The board of directors may also decide to allow shareholders to vote by correspondence by means of a proxy form providing for a positive or negative vote or an abstention on each agenda item. The conditions for voting by correspondence are set out in the articles of association and in the convening notice.

 

The board of directors may decide to arrange for shareholders to be able to participate in the general meeting by conference call, video conference or similar means of communication, whereby (i) the shareholders attending the meeting can be identified, (ii) all persons participating in the meeting can hear and speak to each other, (iii) the transmission of the meeting is performed on an ongoing basis and (iv) the shareholders can properly deliberate without the need for them to appoint a proxyholder who would be physically present at the meeting.

 

Appointment and term limits of members of our board of directors

 

In accordance with our articles of association and the 1915 Law, the members of our board of directors are elected by a resolution of a general meeting of shareholders adopted with a simple majority of the votes validly cast, regardless of the portion of capital represented at such general meeting. Votes are cast for or against each nominee proposed for election to the board and cast votes shall not include votes attaching to shares for which the shareholder has not participated in the vote, has abstained or has returned a blank or invalid vote.

 

Our directors are appointed for a mandate of a one-year term and may be reelected. Members of our board of directors may be removed at any time, with or without cause, by a resolution adopted at a general meeting of our shareholders. Under Luxembourg law, in the case of a vacancy of the office of a director appointed by the general meeting of shareholders, the remaining directors may, unless the articles of association provide differently, fill the vacancy on a provisional basis. In these circumstances, the following general meeting of shareholders shall make the final appointment of the director.

2 

 

Issuance of shares and preferential subscription rights

 

Our shares may be issued pursuant to a resolution of the general meeting of shareholders. The general meeting of shareholders may also delegate the authority to issue shares to the board of directors for a renewable period of five years. The board of directors has been authorized to issue up to 231,924,819 common shares. Such authorization will expire five years after the date of publication in the Luxembourg legal gazette (Recueil Electronique des Sociétés et Associations) of the minutes of the general meeting of shareholders held on June 4, 2020 (unless amended or extended by the general meeting of shareholders).

 

Each holder of shares has preferential subscription rights to subscribe for any issue of shares pro rata to the aggregate amount of such holder’s existing holding of the shares. Each shareholder shall, however, have no preferential subscription right on shares issued for a contribution in kind.

 

Preferential subscription rights may be restricted or excluded by a resolution of the general meeting of shareholders, or by the board of directors if the shareholders so delegate. The general meeting of shareholders has delegated to the board of directors the power to cancel or limit the preferential subscription rights of the shareholders when issuing new shares, so long as the issuance of new shares is carried out through a public offering.

 

If we decide to issue new shares in the future and do not exclude the preferential subscription rights of existing shareholders, we will publish the decision by placing an announcement in the Luxembourg official journal Recueil Electronique des Sociétés et Associations and in a newspaper published in Luxembourg. The announcement will specify the period in which the preferential subscription rights may be exercised. Such period may not be shorter than 14 days from the publication of the offer. The announcement will also specify details regarding the procedure for exercise of the preferential subscription rights. Under Luxembourg law preferential subscription rights are transferable and tradable property rights.

 

Repurchase of shares

 

Nexa Resources is prohibited by the 1915 Law from subscribing for its own shares. Nexa Resources may, however, repurchase its own shares or have another person repurchase shares on its behalf, subject to certain conditions, including:

 

prior authorization of the general meeting of shareholders setting out the terms and conditions of the proposed repurchase, including the maximum number of shares to be repurchased, the duration of the period for which the authorization is given (which may not exceed five years) and the minimum and maximum consideration per share;

 

the repurchase may not reduce the net assets of Nexa Resources on a non-consolidated basis to a level below the aggregate of the issued share capital and the reserves that Nexa Resources must maintain pursuant to the 1915 Law or our articles of association;

 

only fully paid-up shares may be repurchased; and

 

the acquisition offer is made on the same terms and conditions to all the shareholders who are in the same position; however, listed companies may repurchase their own shares on the stock exchange without making an acquisition offer to the shareholders.

 

On September 13, 2018, our shareholders authorized us to purchase, acquire, receive or hold and sell shares of Nexa Resources in accordance with the 1915 Law and any other applicable laws and regulations. The authorization is effective immediately after the general meeting and valid for a period of three years. As of December 31, 2020, there were no authorized share buyback programs.

3 

 

Form and transfer of shares

 

Our shares are issued in registered form only and are freely transferable. Luxembourg law does not impose any limitations on the rights of Luxembourg or non-Luxembourg residents to hold or vote our shares.

 

Under Luxembourg law, the ownership of registered shares is generally evidenced by the inscription of the name of the shareholder, the number of shares held by him or her in the shareholders’ register, which is maintained at our registered office. Each transfer of shares is made by a written declaration of transfer recorded in our shareholders’ register, dated and signed by the transferor and the transferee or by their duly appointed agent. We may accept and enter into its shareholders’ register any transfer based on an agreement between the transferor and the transferee provided a true and complete copy of the agreement is provided to us.

 

Our articles of association provide that, in case our shares are recorded in the register of shareholders on behalf of one or more persons in the name of a securities settlement system or the operator of such a system, or in the name of a professional depositary of securities or any other depositary or of a sub-depositary designated by one or more depositaries, NEXA—subject to a confirmation in proper form received from the depositary—will permit those persons to exercise the rights attaching to those shares, including admission to and voting at general meetings of shareholders. The board of directors may determine the requirements with which such confirmations must comply. Shares held in such manner generally have the same rights and obligations as any other shares recorded in our shareholder register(s).

 

Liquidation rights

 

The liquidation of Nexa Resources shall be decided by a general meeting of shareholders fulfilling the conditions as to attendance and majority required for the amendments of the articles of association. The method of liquidation shall be determined and the liquidators shall be appointed by the general meeting of shareholders. In accordance with the 1915 Law, the assets that remain after payment of all debts and liabilities are distributed to the shareholders, on a pro rata basis.

 

Other Provisions

 

Holders of our common shares have no sinking fund, redemption or conversion rights.

 

Limitations on the right to own securities

 

Neither Luxembourg law nor our articles of association impose any general limitation on the right of nonresidents or foreign persons to hold our common shares or exercise voting rights on our common shares other than those limitations that would generally apply to all shareholders.

 

There is no law, governmental decree or regulation in Luxembourg that would affect the remittance of dividends or other distributions by Nexa Resources to nonresident holders of its common shares, other than withholding tax requirements. In certain limited circumstances, the implementation and administration of international financial sanctions may affect the remittance of dividends or other distributions. There are no specified procedures for nonresident holders to claim dividends or other distributions.

 

Transfer Agent

 

Computershare Trust Company, N.A. is the paying agent for shareholders who hold common shares listed on the NYSE and on the TSX.

4 

Exhibit 8

 

List of Subsidiaries of Nexa Resources S.A.

 

Name of Subsidiary

 

Jurisdiction of Incorporation or Organization

Campos Novos Energia S.A.   Brazil
     
Compañía Minera Shalipayco S.A.C.   Peru
     
Compañía Magistral S.A.C   Peru
     
Compañía Minera Doña Isabel Ltda.   Chile
     
Compañía Minera Gaico S.A.   Peru
     
Consórcio Capim Branco Energia   Brazil
     
Consórcio UHE Igarapava   Brazil
     
IncPac Holding Limited   British Virgin Islands
     
Inversiones Garza Azul S.A.C.   Peru
     

Karmin Holdings Ltda.

 

Brazil

     
L.D.O.S.P.E. Empreendimentos e Participações Ltda.   Brazil
     
L.D.Q.S.P.E. Empreendimentos e Participações Ltda.   Brazil
     
L.D.R.S.P.E. Empreendimentos e Participações Ltda.   Brazil
     
Minera Bongará S.A.   Peru
     
Compañia Minera Cerro Colorado S.A.C.   Peru
     
Minera Chambará S.A.C.   Peru
     
Minera Pampa de Cobre S.A.C.   Peru
     
Mineração Colina Ltda.   Brazil
     
Mineração Dardanelos Ltda.   Brazil
     
Mineração Parnamirim Ltda.   Brazil
     

Mineração Rio Aripuanã Ltda.

 

Brazil

     
Mineração Santa Maria Ltda.   Brazil
     
Mineração Soledade Ltda.   Brazil
     
Nexa Resources Atacocha S.A.A.   Peru
     
Nexa Resources Cajamarquilla S.A.   Peru
     
Nexa Resources El Porvenir S.A.C.   Peru
     
Nexa Recursos Minerais S.A.   Brazil
     
Nexa Resources Peru S.A.A.   Peru
     
Nexa Resources UK Limited   United Kingdom
     
Nexa Resources US Inc.   United States
     
Otavi Mining Investments (Proprietary) Ltd.   Namibia
     
Otjitombo Mining (Proprietary) Ltd.   Namibia
     
Pollarix S.A.   Brazil
     
Rayrock Antofagasta S.A.C.   Peru
     
SMRL Ltda. Pepita 1   Peru
     
SMRL CMA nº 54   Peru
     
Votorantim Andina S.A.   Chile
     
Votorantim Metals Canada Inc.   Canada
     
Votorantim Metals Namibia (Proprietary) Ltd.   Namibia

 

 

Exhibit 12.1

 

I, Tito Botelho Martins Junior, certify that:

 

1.    I have reviewed this annual report on Form 20-F of Nexa Resources S.A.;

 

2.            Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

 

3.            Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the company as of, and for, the periods presented in this report;

 

4.             The company’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15-d-15(f)) for the company and have:

 

(a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the company, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

 

(b) Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

 

(c) Evaluated the effectiveness of the company’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

 

(d) Disclosed in this report any change in the company’s internal control over financial reporting that occurred during the period covered by the annual report that has materially affected, or is reasonably likely to materially affect, the company’s internal control over financial reporting; and

 

5.             The company’s other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the company’s auditors and the audit committee of the company’s board of directors (or persons performing the equivalent functions):

 

(a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the company’s ability to record, process, summarize and report financial information; and

 

(b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the company’s internal control over financial reporting.

 

/s/ Tito Botelho Martins Junior  
Name: Tito Botelho Martins Junior  
Title: President and Chief Executive Officer  
Date:

March 22, 2021

 

 

 

 

Exhibit 12.2

 

I, Rodrigo Menck, certify that:

 

1.   I have reviewed this annual report on Form 20-F of Nexa Resources S.A.;

 

2.             Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

 

3.             Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the company as of, and for, the periods presented in this report;

 

4.             The company’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15-d-15(f)) for the company and have:

 

(a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the company, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

 

(b) Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

 

(c) Evaluated the effectiveness of the company’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

 

(d) Disclosed in this report any change in the company’s internal control over financial reporting that occurred during the period covered by the annual report that has materially affected, or is reasonably likely to materially affect, the company’s internal control over financial reporting; and

 

5.             The company’s other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the company’s auditors and the audit committee of the company’s board of directors (or persons performing the equivalent functions):

 

(a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the company’s ability to record, process, summarize and report financial information; and

 

(b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the company’s internal control over financial reporting.

 

/s/ Rodrigo Menck  
Name: Rodrigo Menck  
Title: Senior Vice President Finance and Group Chief Financial Officer  
Date: March 22, 2021  

 

 

 

Exhibit 13.1

 

Certification

Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002
(Subsections (a) and (b) of Section 1350, Chapter 63 of Title 18, United States Code)

 

Pursuant to section 906 of the Sarbanes-Oxley Act of 2002 (subsections (a) and (b) of section 1350, chapter 63 of Title 18, United States Code), each of the undersigned officers of Nexa Resources S.A. (the “Company”), does hereby certify, to such officer’s knowledge, that:

 

The Annual Report on Form 20-F for the year ended December 31, 2020 (the “Form 20-F”) of the Company fully complies with the requirements of section 13(a) or 15(d) of the Securities Exchange Act of 1934 and information contained in the Form 20-F fairly presents, in all material respects, the financial condition and results of operations of the Company.

 

/s/ Tito Botelho Martins Junior  
Name: Tito Botelho Martins Junior  
Title: President and Chief Executive Officer  
Date: March 22, 2021  

 

/s/ Rodrigo Menck  
Name: Rodrigo Menck  
Title: Senior Vice President Finance and Group Chief  
  Financial Officer  
Date: March 22, 2021  

 

A signed original of this written statement required by Section 906 of the Sarbanes-Oxley Act of 2002 has been provided to the Company and will be retained by the Company and furnished to the Securities and Exchange Commission or its staff upon request.

 

 

 

Exhibit 15.1

 

(GRAPHIC)  

 

 

 

 

Technical Report Summary on the Cerro Lindo Mine, Department of Ica, Peru

 

SLR Project No: 233.03246.R0000

 

Prepared by 

SLR Consulting (Canada) Ltd. 

55 University Ave., Suite 501 

Toronto, ON M5J 2H7 

for

 

Nexa Resources S.A. 

Rúa Guaicuí, 20 – 14° Andar 

Belo Horizonte/MG 

30380-380

 

Effective Date – December 31, 2020 

Signature Date - January 29, 2021

 

FINAL

 

Distribution: 1 copy – Nexa Resources S.A.
  1 copy – SLR Consulting (Canada) Ltd.

1  

 

 

 

Contents

 

1.0 EXECUTIVE SUMMARY 1-1
     
1.1 Summary 1-1
1.2 Economic Analysis 1-7
1.3 Technical Summary 1-12
     
2.0 INTRODUCTION 2-1
     
2.1 Site Visits 2-1
2.2 Sources of Information 2-2
2.3 List of Abbreviations 2-3
     
3.0 PROPERTY DESCRIPTION 3-1
     
3.1 Location 3-1
3.2 Land Tenure 3-1
3.3 Surface Rights and Easements 3-12
3.4 Tax Stability Agreement and Mining Special Tax 3-16
3.5 Material Government Consents 3-16
     
4.0 ACCESSIBILITY, CLIMATE, LOCAL RESOURCES, INFRASTRUCTURE AND PHYSIOGRAPHY 4-1
     
4.1 Accessibility 4-1
4.2 Climate 4-1
4.3 Local Resources 4-1
4.4 Infrastructure 4-1
4.5 Physiography 4-2
     
5.0 HISTORY 5-1
     
5.1 Exploration and Development History 5-1
5.2 Past Production 5-1
     
6.0 GEOLOGICAL SETTING, MINERALIZATION, AND DEPOSIT 6-1
     
6.1 Regional Geology 6-1
6.2 Local and Property Geology 6-3
6.3 Deposit Geology 6-9
6.4 Mineralization 6-11
6.5 Deposit Types 6-14
     
7.0 EXPLORATION 7-1
     
7.1 Exploration 7-1
7.2 Drilling 7-10
7.3 Hydrogeology 7-20
7.4 Geotechnical Data, Testing, and Analysis 7-20
 
 
 
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8.0 SAMPLE PREPARATION, ANALYSES, AND SECURITY 8-1
     
8.1 Density Determinations 8-1
8.2 Analytical and Test Laboratories 8-4
8.3 Sample Preparation and Analysis 8-5
8.4 Sample Security 8-7
8.5 Quality Assurance and Quality Control 8-7
8.6 QA/QC Recommendations 8-28
     
9.0 DATA VERIFICATION 9-1
     
9.1 Databases 9-1
9.2 Internal Verification 9-1
9.3 External Verification 2003-2017 9-2
9.4 SLR Verification 9-2
     
10.0 MINERAL PROCESSING AND METALLURGICAL TESTING 10-1
     
10.1 Recent Test Work 10-1
10.2 LOM Plan 10-8
     
11.0 MINERAL RESOURCE ESTIMATES 11-1
     
11.1 Summary 11-1
11.2 Resource Database 11-3
11.3 Geological Interpretation 11-6
11.4 Geological Modelling 11-7
11.5 Domain Modelling 11-10
11.6 Resource Assays 11-23
11.7 Treatment of High Grade Assays 11-26
11.8 Compositing 11-35
11.9 Trend Analysis 11-38
11.10 Search Strategy and Grade Interpolation Parameters 11-42
11.11 Bulk Density 11-43
11.12 Block Models 11-52
11.13 Net Smelter Return and Cut-off Value 11-53
11.14 Classification 11-57
11.15 Block Model Validation 11-64
11.16 Mineral Resource Reporting 11-73
11.17 Comparison to Previous Mineral Resource Estimates 11-77
     
12.0 MINERAL RESERVE ESTIMATES 12-1
     
12.1 Summary 12-1
12.2 Dilution 12-2
12.3 Extraction 12-3
12.4 Net Smelter Return and Cut-off Value 12-3

 
 
 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
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13.0 MINING METHODS 13-1
     
13.1 Background 13-1
13.2 Mine Design 13-4
13.3 Mine Method 13-6
13.4 Geotechnical Considerations 13-8
13.5 Hydrogeological Considerations 13-13
13.6 Life of Mine Plan 13-13
13.7 Infrastructure 13-15
13.8 Mine Equipment 13-18
13.9 Manpower 13-20
     
14.0 PROCESSING AND RECOVERY METHODS 14-1
     
14.1 Process Description 14-1
     
15.0 INFRASTRUCTURE 15-1
     
15.1 Site Access 15-1
15.2 Power Supply 15-1
15.3 Water Supply 15-2
15.4 Site Buildings 15-2
15.5 Mine Waste Management 15-4
     
16.0 MARKET STUDIES 16-1
     
16.1 Markets 16-1
16.2 Contracts 16-4
     
17.0 ENVIRONMENTAL STUDIES, PERMITTING, AND PLANS, NEGOTIATIONS, OR AGREEMENTS WITH LOCAL INDIVIDUALS OR GROUPS 17-1
     
17.1 Environmental Studies 17-1
17.2 Mine Waste and Water Management 17-9
17.3 Project Permitting 17-12
17.4 Social or Community Requirements 17-15
17.5 Mine Closure Requirements 17-22
     
18.0 CAPITAL AND OPERATING COSTS 18-1
     
18.1 Capital Costs 18-1
18.2 Operating Costs 18-1
     
19.0 ECONOMIC ANALYSIS 19-1
     
19.1 Economic Criteria 19-1
19.2 Cash Flow 19-3
19.3 Sensitivity Analysis 19-7
     
20.0 ADJACENT PROPERTIES 20-1

 
 
 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
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21.0 OTHER RELEVANT DATA AND INFORMATION 21-1
     
22.0 INTERPRETATION AND CONCLUSIONS 22-1
     
22.1 Geology and Mineral Resources 22-1
22.2 Mining and Mineral Reserves 22-1
22.3 Mineral Processing 22-2
22.4 Environment, Permitting and Social Considerations 22-2
22.5 Costs and Economic Analysis 22-3
     
23.0 RECOMMENDATIONS 23-1
     
23.1 Geology and Mineral Resources 23-1
23.2 Mining and Mineral Reserves 23-2
23.3 Mineral Processing 23-2
23.4 Environment, Permitting and Social Considerations 23-2
23.5 Costs and Economic Analysis 23-3
     
24.0 REFERENCES 24-1
     
25.0 RELIANCE ON INFORMATION PROVIDED BY THE REGISTRANT 25-1
     
26.0 DATE AND SIGNATURE PAGE 26-1

 
 
 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
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TABLEs

 

Table 1-1: Discounted Cash Flow Summary 1-10
Table 1-2: Summary of Mineral Resources – December 31, 2020 1-14
Table 1-3: Summary of Mineral Reserves – December 31, 2020 1-15
Table 1-4: Sustaining Capital Cost 1-18
Table 1-5: Mine Operating Cost Estimate 1-19
Table 3-1: Cerro Lindo Mineral Rights 3-2
Table 3-2: Cerro Lindo Beneficiation Concession 3-5
Table 3-3: Annual Fee per Mineral Right and Beneficiation Concession – 2020 3-10
Table 3-4: Main Government Consents 3-16
Table 5-1: Production History 5-2
Table 6-1: Dimensions of Main Mineralized Bodies within Mining Production Areas 6-12
Table 6-2: General Features of the Cerro Lindo Deposit 6-15
Table 7-1: 2019 Rock Chip Sampling Results At Ventanalloc Target 7-2
Table 7-2: 2019 Rock Chip Sampling Results At Toldo Chico Target 7-2
Table 7-3: Cerro Lindo Drilling Summary as of March 2, 2020 7-10
Table 7-4: Summary of Drilling Excluded from Mineral Resource Estimate as of March 2, 2020 7-11
Table 7-5: Summary of Drilling Included in Mineral Resource Estimate as of March 2, 2020 7-12
Table 7-6: Channel Sampling Summary at Cerro Lindo 7-12
Table 7-7: Core Recovery by Domain - 2019-2020 7-18
Table 7-8: Geotechnical Drilling - 2015-2020 7-21
Table 7-9: Physical Property Test 7-23
Table 7-10: Load Testing 7-23
Table 8-1: Number of Density Measurements by Sample Type and Year 8-1
Table 8-2: Analytical and Test Laboratories 8-4
Table 8-3: Detection Limits at Mine Laboratory, Inspectorate Lima and Certimin Lima 8-7
Table 8-4: QA/QC Sample Insertion Rates, 2014-2016 8-10
Table 8-5: 2014-2016 QA/QC Program Summary 8-10
Table 8-6: Control Sample Insertion Rate and Failure Criteria 8-11
Table 8-7: Summary of QA/QC Submittals from 2017 to 2020 8-12
Table 8-8: 2017-2020 Cerro Lindo In-House CRM Values 8-14
Table 8-9: 2017-2020 Cerro Lindo In-House CRM Performance 8-15

 
 
 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
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Table 8-10: 2017-2020 Cerro Lindo Blanks Performance 8-23
Table 8-11: 2017-2020 Cerro Lindo Duplicate Performance 8-25
Table 8-12: ALS Lima Versus Primary Laboratory Check Results - October, 2017 to April, 2019 8-27
Table 9-1: SLR Assay Certificate Verification Results 9-3
Table 10-1: Comminution Test Work Results for 2019 Geometallurgical Samples 10-4
Table 10-2: Flotation Composite Constituents 10-4
Table 10-3: Average of Locked Cycle Test Concentrate Analyses for the Last Two Cycles 10-5
Table 10-4: Bulk Rougher Concentrates from Variability Tests 10-6
Table 10-5: Zinc Rougher Concentrates from Variability Tests 10-7
Table 10-6: Summary of Historical Performance and LOM Plan 10-10
Table 11-1: Summary of Mineral Resources – December 31, 2020 11-1
Table 11-2: Mineral Resource Estimate by Mineralization Domains – December 31, 2020 11-2
Table 11-3: Excluded Holes 11-4
Table 11-4: Geological Domains 11-6
Table 11-5: Zn, Cu, Ag and Pb Grade Domains 11-10
Table 11-6: Estimation Domains 11-21
Table 11-7: Estimation Domain Raw Assay Statistics 11-24
Table 11-8 : Grade Capping Levels 11-27
Table 11-9: Capped Assay Statistics 11-31
Table 11-10: Estimation Domain Composite Statistics 11-36
Table 11-11: Variogram Parameters 11-41
Table 11-12: Zinc Estimation Parameters 11-42
Table 11-13: Copper Estimation Parameters 11-43
Table 11-14: Density Data 11-44
Table 11-15: Assigned Density Values 11-44
Table 11-16: Density Capping Values 11-46
Table 11-17: Block Estimation Parameters for Bulk Density 11-47
Table 11-18: Statistical Comparison of Blocks versus Composites: Density 11-48
Table 11-19: Block Model Setup 11-52
Table 11-20: Block Model Attribute Descriptions 11-53
Table 11-21: Resource NSR Data 11-54
Table 11-22: Average NSR Factors 11-55
Table 11-23: Comparison Between Estimates (OK/ID³), NN and Composite Means 11-64

 
 
 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
Technical Report Summary - January 29, 2021                
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Table 11-24: Cerro Lindo Comparison of 2020 Versus 2019 Mineral Resources 11-78
Table 12-1: Summary of Mineral Reserves – December 31, 2020 12-1
Table 12-2: Mine Dilution Factors 12-2
Table 12-3: Mine Stope Extraction Factors 12-3
Table 12-4: NSR Data 12-4
Table 12-5: Average NSR Factors 12-5
Table 13-1: Design Factors for Lithologies 13-9
Table 13-2: Geomechanical Classification 13-10
Table 13-3: Life of Mine Plan 13-14
Table 13-4: Mine Equipment List 13-18
Table 13-5: Equipment Performance Criteria and Productivities 13-19
Table 13-6: Nexa Mine Personnel 13-20
Table 13-7: Mine Contractor List 13-20
Table 16-1: Third Party Contractors 16-5
Table 17-1: Summary of Key Environmental Effects and Management Strategies 17-5
Table 17-2: Environmental, Mine Closure and Tailings Disposal Licences 17-13
Table 17-3: Summary of Main Closure Activities 17-24
Table 18-1: Sustaining Capital Cost 18-1
Table 18-2: Mine Operating Cost Estimate 18-2
Table 18-3: Manpower Distribution 18-3
Table 18-4: Contractors List - December 2020 18-3
Table 19-1: After-Tax Cash Flow Summary 19-4
Table 19-2: Cash Flow Analysis 19-7
Table 19-3: After-Tax Sensitivity Analysis 19-8

  

FIGURES 

 

Figure 3-1: Mine Location 3-6
Figure 3-2: Land Tenure 3-7
Figure 3-3: Surface Rights 3-14
Figure 6-1: Regional Geology 6-2
Figure 6-2: Geological Map of the Cerro Lindo Property 6-4
Figure 6-3: Local Stratigraphic Column 6-5
 
 
 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
Technical Report Summary - January 29, 2021                
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Figure 6-4: Vertical Section through Mineralized Bodies Showing Mineralization Types 6-8
Figure 6-5: Cross-Section Schematic of the Massive Sulphide at Cerro Lindo 6-10
Figure 6-6: Main Mineralized Bodies within Mining Production Areas 6-13
Figure 6-7: Schematic Section Transversal to Sulphide Orebodies and Intrusions 6-17
Figure 7-1: 3D Chargeability Model and New Targets 7-4
Figure 7-2: Brownfield Exploration Targets by Priority 7-8
Figure 7-3: Brownfield Exploration Targets – Section and Plan View 7-9
Figure 7-4: Drill Hole Location 7-14
Figure 7-5: Schematic of Selected Drilling and Related Geological Interpretation 7-15
Figure 7-6: Location of Channel Sampling (2007-2016) 7-16
Figure 7-7: Histograms of RDQ and RMR 7-22
Figure 8-1: Distribution of Density Samples used for 2020 Mineral Resource Estimate by Year Analyzed 8-3
Figure 8-2: Sample Preparation and Quality Control Flowsheet (Milpo 2000–2001 Program) 8-6
Figure 8-3: CRM “MCL06” Results for Zinc – Mine and Certimin Laboratories – (2017-2018) 8-19
Figure 8-4: CRM “MCL07” Results for Copper – Mine and Certimin Laboratories – (2017-2018) 8-20
Figure 8-5: Cerro Lindo CRM Zn Performance for PECLSDT003 (2018-2020) 8-21
Figure 8-6: Cerro Lindo CRM “PECLSDT003 (2018-2020)” Results for Copper – Inspectorate Mine Laboratory 8-22
Figure 8-7: 2019-2020 Cerro Lindo Blank Zn and Cu Assays – Inspectorate Mine Laboratory 8-24
Figure 8-8: 2019-2020 Cerro Lindo Pulp Duplicates Zn and Cu Assays – Inspectorate Mine Laboratory 8-26
Figure 8-9 : 2018-2019 2020 Cerro Lindo Zn and Cu External Check Assays – Inspectorate Mine  Laboratory 8-28
Figure 9-1: Density Sampling Coverage Relative to Mineral Resources and Mineral Reserves 9-4
Figure 10-1: Sample Representation of Major Lithologies 10-2
Figure 10-2: Sample Representation of Orebodies 10-2
Figure 10-3: Location of Individual Samples in the Block Model 10-3
Figure 10-4: Locked Cycle Flotation Test Flowsheet 10-5
Figure 11-1: 3D View of Cerro Lindo Mineralized Solid and Drill holes 11-5
Figure 11-2: Structural Trends 11-8
Figure 11-3: Geological Model Shown with and without Dikes 11-9
Figure 11-4: Zn Distribution in SPB and SSM Domains 11-12
Figure 11-5: Cu Distribution in SPB and SPP Domains 11-13
 
 
 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
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Figure 11-6: Ag Distribution in SSM and VM Domains 11-14
Figure 11-7: SPB and SPP High and Low Grade Zn Domains – Plan View 11-15
Figure 11-8: SSM and VM High and Low Zn Domains – Plan View 11-16
Figure 11-9: SPB and SPP High and Low Grade Cu Domains – Plan View 11-17
Figure 11-10: SSM and VM High and Low Grade Cu Domains – Plan View 11-18
Figure 11-11: SPB and SPP High and Low Grade AG-Pb Domains – Plan View 11-19
Figure 11-12: SSM and VM High and Low Grade Ag-Pb Domains – Plan View 11-20
Figure 11-13: Capping Analysis for SPB Zn High Grade Mineralization 11-28
Figure 11-14: Capping Analysis for SPB Cu High Grade Mineralization 11-29
Figure 11-15: Capping Analysis for SPB Ag High Grade Mineralization 11-30
Figure 11-16: Copper Decile Analysis, Probability Plot, Histogram and Desintegration Analysis for Domain SPB HG 11-34
Figure 11-17: Composite Length Comparisons 11-35
Figure 11-18: Zn Variogram for Mineralization SPB Domain 11-39
Figure 11-19: Cu Variogram for Mineralization SPP Domain 11-40
Figure 11-20: Density Sample Location by Geological Domains 11-45
Figure 11-21: Density Capping Analysis for SPB Domain 11-46
Figure 11-22: Plan View of Block and Density Samples 11-49
Figure 11-23: SPB Swath Plots – Density Values 11-50
Figure 11-24: SPP Swath Plots – Density Values 11-50
Figure 11-25: SSM Swath Plots – Density Values 11-51
Figure 11-26: VM Swath Plots – Density Values 11-51
Figure 11-27: Zinc Recovery 11-56
Figure 11-28: Copper Recovery 11-56
Figure 11-29: Lead Recovery 11-57
Figure 11-30: Validation of Classification (SPB and SPP) 11-61
Figure 11-31: Validation of Classification (SSM and VM) 11-62
Figure 11-32: Final Classification Designation 11-63
Figure 11-33: Swath Plot: Zn Grade Variation along X, Y, and Z 11-68
Figure 11-34: Swath Plot: Cu Grade Variation along X, Y, and Z 11-69
Figure 11-35: Vertical Section Showing Zn Block versus Composite Grades 11-70
Figure 11-36: Vertical Section Showing Cu Block versus Composite Grades 11-71
Figure 11-37: Plant Versus Resource Model Reconciliation 11-72
 
 
 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
Technical Report Summary - January 29, 2021                
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Figure 11-38: Plan View of Mineral Resources Inclusive and Exclusive of Mineral Reserves 11-75
Figure 11-39: Longitudinal View of Mineral Resources Inclusive and Exclusive of Mineral Reserves 11-76
Figure 12-1: Zinc Recovery 12-5
Figure 12-2: Lead Recovery 12-6
Figure 12-3: Copper Recovery 12-6
Figure 13-1: Longitudinal Section of the Mine 13-2
Figure 13-2: Simplified Plan View of the 1820 m Level 13-3
Figure 13-3: Cerro Lindo Underground Mine Design 13-5
Figure 13-4: Production Drilling Layout 13-7
Figure 13-5: Stability and Rock Quality Indices 13-9
Figure 13-6: Ground Support Standards 13-11
Figure 13-7: Finite Element Model for T320-1880 Stope Safety Factor Assessment 13-12
Figure 13-8: LOM Production Profile 13-13
Figure 13-9: Cerro Lindo Ventilation Circuit Schematic 13-16
Figure 14-1: Cerro Lindo Process Plant Layout 14-2
Figure 14-2: Simplified Process Flowsheet 14-3
Figure 15-1: Surface Plan of Infrastructure 15-3
Figure 15-2: Mine Site Layout and Waste Management Areas 15-5
Figure 15-3: Tailings Dry Stack Pahuaypite 2 and Supporting Infrastructure 15-7
Figure 16-1: Zinc Price Outlook (2020-2025) 16-2
Figure 16-2: Refined Copper Market Balance (2020-2025) 16-3
Figure 16-3: Copper Price Outlook (2020-2025) 16-4
Figure 17-1: Water Supply System for Cerro Lindo Mine 17-11
Figure 18-1: Operating Cost Profile 18-2
Figure 19-1: After-Tax NPV Sensitivity Graph 19-9
   
 
 
 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
Technical Report Summary - January 29, 2021                
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1.0 Executive Summary

 

1.1 Summary

 

SLR Consulting Ltd (SLR) was retained by Nexa Resources S.A. (Nexa) to prepare an independent Technical Report Summary on the Cerro Lindo Mine (Cerro Lindo or the Mine), located in the Department of Ica, Peru. The purpose of this report is to support the Mineral Resource and Mineral Reserve estimates for the Mine as of December 31, 2020. This Technical Report Summary conforms to United States Securities and Exchange Commission’s (SEC) Modernized Property Disclosure Requirements for Mining Registrants as described in Subpart 229.1300 of Regulation S-K, Disclosure by Registrants Engaged in Mining Operations (S-K 1300) and Item 601 (b)(96) Technical Report Summary. SLR visited the property from June 4 to 7 and June 18 to 20, 2019.

 

Nexa is a publicly traded company on the Toronto Stock Exchange (TSX) and the New York Stock Exchange (NYSE). It is a reporting issuer in all provinces and territories of Canada.

 

Nexa is a large-scale, low-cost, integrated zinc producer with over 60 years of experience developing and operating mining and smelting assets in Latin America. Nexa has a diversified portfolio of polymetallic mines (zinc, lead, copper, silver, and gold) and also greenfield projects at various stages of development in Brazil and Peru. In Brazil, Nexa owns and operates two underground mines, Vazante and Morro Agudo (Zn and Pb). It also operates two zinc smelters in Brazil (Três Marias and Juiz de Fora). In Peru, Nexa operates the El Porvenir (Zn, Pb, Cu, and Ag), Cerro Lindo (Zn, Cu, Pb, and Ag), and Atacocha (Zn, Cu, Pb, Au, and Ag) mines, as well as the Cajamarquilla zinc smelter near Lima. Nexa’s development projects in Peru include Magistral, Shalipayco, Florida Canyon (JV with Solitario), Hilarión, and Pukaqaqa. In Brazil, Nexa is developing the Aripuanã Zinc Project (Zn, Pb, Cu, Au, and Ag), which is currently under construction.

 

Cerro Lindo is located in the Chavín District, Chincha Province, Ica Department of Peru, approximately 268 km southeast of Lima. Nexa owns a total of 80.16% in the Mine that corresponds to the sum of Nexa’s direct interest in Nexa Resources Peru S.A.A. (Nexa Peru) (0.17%) and Nexa’s indirect interest in Nexa Peru (80.06%) through its controlled company Nexa Resources Cajamarquilla S.A. (99.91%), and the remaining 19.76% are floating shares. Cerro Lindo commenced operations in 2007 and comprises an underground zinc-lead-copper-silver mine, a conventional comminution flotation process plant, a coastal desalination plant, and associated infrastructure. The Mine produces separate zinc, lead, and copper concentrates with silver content. In 2020, the Mine produced 105,876 tonnes (t) of zinc, 32,499 t of copper, 15,688 t of lead, and 4,254,239 ounces (oz) of silver. As of December 2020, the Mine is scheduled to produce a total of approximately 52 million tonnes (Mt) of Mineral Reserves over a mine life of nine years.

 

Production in 2020 was significantly lower than in 2019 impacted by the COVID-19 pandemic and associated production interruptions. On March 15, 2020, the Peruvian Government declared a national emergency and imposed operating business restrictions including on the mining sector. The quarantine period was initially expected to last until the end of March but was subsequently extended up to May 10, 2020. As a consequence of the government restrictions, Nexa suspended production at Cerro Lindo. During this period, mining activities were limited to critical operations with a minimum workforce to ensure appropriate maintenance, safety, and security. On May 6, the Peruvian Government announced the conditions for the resumption of operations for different sectors, including mining operations above 5,000 tonnes per day (tpd). Cerro Lindo operations, which were suspended on March 18, restarted production on May 11, 2020, following the end of the quarantine period. After the resumption of operations, Cerro Lindo ramped up production to pre-pandemic levels by June 2020.

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

Technical Report Summary - January 29, 2021

 

            
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1.1.1 Conclusions

 

SLR has the following conclusions by area.

 

1.1.1.1 Geology and Mineral Resources

 

As of December 31, 2020, exclusive of Mineral Reserves, Measured Mineral Resources are estimated to total 4.4 Mt at 2.00% Zn, 0.20% Pb, 0.67% Cu, and 19.61 g/t Ag and Indicated Mineral Resources are estimated to total 3.46 Mt at 1.37% Zn, 0.25% Pb, 0.45% Cu, and 24.96 g/t Ag. In addition, Inferred Mineral Resources are estimated to total 8.71 Mt at 1.28% Zn, 0.35% Pb, 0.33% Cu, and 31.23 g/t Ag.

 

Cerro Lindo is a Kuroko-style volcanogenic massive sulphide (VMS) deposit that comprises a number of lens-shaped massive and semi-massive sulphide bodies.

 

Three massive sulphide units, one semi-massive sulphide unit, and one mineralized volcanic rock unit have been recognized.

 

The control of mineralization is lithological, mineralogical, and structural. Most copper mineralization is located in a pyritic massive sulphide unit and most zinc mineralization is located in baritic massive sulphide units, with lesser disseminated mineralization as patches or stringers in the semi-massive sulphide and mineralized volcanic units.

 

The geological setting, geophysical studies, surface samples and geological mapping of the Cerro Lindo area present good exploration potential, as a number of targets have already been identified within a ten kilometre radius of the mining operation.

 

Protocols for drilling, sampling preparation and analysis, verification, and security meet industry standard practices and are appropriate for the purposes of a Mineral Resource estimate.

 

The quality assurance/quality control (QA/QC) program as designed and implemented by Nexa is adequate, with no significant bias, to support the resource database. The resource database was verified by SLR and is suitable for Mineral Resource estimation.

 

The geological models are reasonably constructed using available geological information and are appropriate for Mineral Resource estimation.

 

The assumptions, parameters, and methodology used for the Cerro Lindo Mineral Resource estimate are appropriate for the style of mineralization and proposed mining methods.

  

1.1.1.2 Mining and Mineral Reserves

 

As of December 31. 2020, Proven and Probable Mineral Reserves are estimated to total 52.10 Mt at 1.44% Zn, 0.20% Pb, 0.61% Cu, and 21.17 g/t Ag.

 

Dilution and extraction factors follow the historical trend and are considered appropriate for the type of stoping methods employed at Cerro Lindo.

 

The level of dilution will likely increase in the latter years of production as the stopes on the fringes of the deposit will increase exposing the stopes to more external dilution.

 

The level of extraction will likely decrease under similar circumstances as more care will be required to avoid excess dilution in the ore.
 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

Technical Report Summary - January 29, 2021

 

            
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Modifications to the mining approach for the areas requiring a more conventional method such as cut and fill (C&F) will be required in the latter years when mining the fringes of the deposit. Paste backfill delivery is an issue when stopes are distant from the paste fill source requiring dilution with water which in turn can result in lower strength backfill. This does not represent a significant risk to the Mineral Reserve estimate, as C&F represents a small amount of the total Mineral Reserves. Pastefill can also be substituted with cemented rock fill (CRF). CRF can be mixed underground closer to the C&F stopes.

 

1.1.1.3 Mineral Processing

 

The development of a geometallurgical model to predict metallurgical response during future processing at Cerro Lindo remains a work in progress. Additional work and metallurgical testing are necessary to confirm the validity of the relationships derived to date for throughput, grinding media consumption, recovery, and concentrate quality.

 

Analysis of historical production demonstrates that recoveries of copper, lead, and zinc are related to their head grades, while silver recoveries to the copper and lead concentrates tend to follow the copper and lead head grades.

 

Average life of mine (LOM) planned head grades of copper, lead, and silver for the next three years are similar to those experienced from 2016 to 2020 at 0.48%, 0.25%, and 0.70 oz/t, respectively, while the planned head grades of zinc decrease steadily from 1.8% after 2020.

 

Head grades towards the end of the LOM are anticipated to decrease, particularly those of zinc. Forecast recoveries and concentrate grades are initially in line with those of recent years, and then predicted to fall as head grades decrease.

 

Apart from decreasing head grades, no fundamental changes to the concentrator feed are anticipated, and in the Qualified Person’s (QP) opinion, based on recent processing plant performance, the forecast recoveries and concentrate qualities for the near future are reasonable. With end of LOM zinc and lead head grades being well below the historical ranges, however, there is a risk that actual recoveries may be lower than forecast due to the lack of data on processing material with these low head grades.

 

A small amount of transition or supergene ore has been identified in two stopes, and test work is underway to determine economical alternatives for processing the ore, e.g., by campaigning the supergene material through the processing plant using conditions and reagents optimized specifically for this material.

 

1.1.1.4 Environment, Permitting and Social Considerations

 

No known environmental issues were identified during the site visit and documentation review. The Cerro Lindo Mine operation complies with applicable Peruvian permitting requirements and Nexa maintains a list of permits for the Project, which was provided to SLR. The approved permits address the authority’s requirements for operation of the underground mine, tailings storage facilities (TSF), waste rock dumps, process plant, water usage, and effluents discharge. There is no discharge of industrial or domestic water to the environment at the mine site.

 

There is a comprehensive Environmental Management Plan (EMP) in place, which includes a complete monitoring program for effluent discharges, gas emissions, air quality, non-ionizing radiation, noise, surface water quality, groundwater quality, soil quality, terrestrial biology (vegetation and wildlife), and aquatic biology. Cerro Lindo reports the results of the monitoring program to the authorities according to the frequency stated in the approved resolutions and no compliance issues have been raised by the authorities. In the SLR QP’s opinion the proposed environmental plans are adequate to address potential issues related to environmental compliance.
 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

Technical Report Summary - January 29, 2021

 

            
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Regarding the tailings dry-stack storage facilities, some movement of the tailings relative to the foundation has been noted from the tailings monitoring data, however, phreatic levels in the tailings are very low and the range of movement is considered to be within normal parameters. It is noted that the likelihood of the mine site experiencing a severe seismic event is relatively high given the mine site proximity to a major tectonic plate subduction zone.

 

Water management involves complete recirculation of water at the mine site where there is no fresh water withdrawal from natural water bodies and there is no discharge of industrial or treated sewage water to the environment. Fresh water is being supplied from a desalination plant located at the coast to meet site and process water make-up requirements. Water quality monitoring is carried out monthly at stations located along the Topará Creek at the mine site and in Jahuay beach at the discharge location from the desalination plant.

 

A Mine Closure Plan has been developed for all the Mine components within the context of Peruvian legislation and is periodically updated.

 

A social baseline description, assessment of socio-economic impacts, and a social management plan have been carried out to mitigate negative impacts and maximize positive benefits of the Cerro Lindo Mine. These components are generally consistent with social impact assessment practices. The Social Management Plan is comprised of three plans (Communications Plan, Community Relations Plan, and Community Development Plan) and includes measures and indicators to track social management performance. Nexa implements a complaint register to gather and respond to complaints from the public. In the SLR QP’s opinion the Social Management Plan and the grievance mechanism in place are adequate to address potential issues related to local communities.

 

Nexa hires from the local workforce when possible, both for skilled and unskilled workers. Outreach is conducted to the local community through social and employment programs.

 

The review of social aspects indicates that, at present, Nexa’s operations at the Cerro Lindo site in Peru are a positive contribution to sustainability and community well-being. Nexa has established and continues to implement its various Corporate policies, procedures, and practices in a manner consistent with relevant International Finance Corporation (IFC) Performance Standards. Nexa has, and continues to make, a positive contribution to the communities most affected by the Mine and has done a thorough job in collecting information to support its environmental effects assessment. Information regarding the outcomes of the complaints and grievances reports and site-specific health and safety practices was not provided at the time of this review, however, the corporate policies that guide these activities are clear and aligned with IFC Performance Standards.

 

The water quality concerns outside of the mine site that communities express from time to time remain a risk for the operations at Cerro Lindo.

 

1.1.1.5 Costs and Economic Analysis

 

SLR reviewed the sustaining capital costs and considers them to be appropriate for the remaining mine life. The sustaining capital costs are spread over the LOM period from 2021 to 2029, with mine closure in 2030. The bulk of the sustaining capital is mine development required to both access and develop the stoping blocks for mining. Equipment replacement is comprised of new equipment and equipment overhauls.

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

Technical Report Summary - January 29, 2021

 

            
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The LOM operating cost forecast reflects the existing operating status of the mine. The SLR QP has reviewed recent operating costs and is of the opinion that the forecast is appropriate for the Cerro Lindo mine operation. Cerro Lindo staff also continue to assess operating efficiencies and approaches in efforts to improve operating costs in the different cost centres.

 

The economics of the Cerro Lindo mine operation are robust over the LOM, confirming that the Cerro Lindo Mineral Reserves are economically viable. The economic analysis shows an after-tax net present value (NPV), at an 9% base discount rate, of $304 million.

 

1.1.2 Recommendations

 

SLR has the following recommendations by area.

 

1.1.2.1 Geology and Mineral Resources

 

1. Improve reconciliation processes by implementing a formal procedure and by forming a multi-disciplinary team to organize and analyze reconciliation results so that production data can be used to calibrate future resource and reserve models.

 

2. Investigate the potential 5% negative bias for lead at Inspectorate Lima.

 

3. Incorporate controls to reduce failure rates observed for some lead and silver CRMs. 

 

4. Actively monitor blank results so any contamination issues can be corrected immediately, particularly the mine samples where there is no remaining core for re-analysis. 

 

5. Take density measurements for pyritic oxidized sulphides (SOP), baritic oxidized sulphides (SOB), and leached massive sulphides (SLB) domains, and collect more density samples at the extremities of the mineralization where resource and reserve shapes were generated. 

 

6. Investigate building grade domains without separating them by geological domain to preserve grade continuity, evaluate incorporating mineralogy data, and review the geometry and trends of the grade domains 

 

7. Improve dynamic anisotropy (DA) angles particularly for the OB1 area based on grade trends and structural interpretations and potential further sub-domaining.

 

8. Continuously improve post-mineralization dike modelling to capture more of the logged intercepts and core angles, as well as contacts based on the underground mapping. Dikes are important to delimit internal waste and to guide the local interpolation strategy as some of them are behaving like faults by controlling the mineralization trends.

 

9. Build a more detailed structural model and structural domains to customize local search anisotropies and directions.  It appears that there are at least four main structural trends present (northwest-southeast dipping northeast, northwest-southeast dipping southwest, northeast-southwest dipping northwest, and west-northwest/east-southeast dipping northwest and plunging west-northwest) that should be investigated further. Some mineralization domains appear to have mineralization trending in various directions due to local faulting and folding and further sub-domaining may be warranted. 

 

10. Using the production data, monitor the chosen drill spacing for SSM and VM to determine if sufficient confidence is provided to support detailed mine planning, as these domains show less grade continuity and more grade variability than the massive sulphide domains. 
 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

Technical Report Summary - January 29, 2021

 

            
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11. Optimize resource shapes to reduce unnecessary internal dilution and improve grades, and possibly generate more shapes that were not built due to the resource shape construction methodology used.

 

12. Generate a no survey solid to account for the mined-out areas that were not surveyed, and document work to support the resultant solid.

 

13. Document all the data support to define non-recoverable solids and document any changes.

 

14. Complete the proposed 2021 exploration program, consisting of a 35,100 m of diamond drilling, and continue with advanced exploration, including geological mapping, and geochemical and geophysical surveys. The 2021 exploration program budget is approximately US$7.1 million.

 

15. Complete the proposed 2021 mine geology drilling, consisting of 48,000 m with a goal of upgrading Inferred Mineral Resources to Indicated or Measured Resources (recategorization drilling) and for mine planning purpose (infill drilling) and ultimately convert them into Probable or Proven Mineral Reserves. The 2021 mine geology drilling program budget is approximately US$3.1 million.

 

1.1.2.2 Mining and Mineral Reserves

 

1. Review the stope designs to address the potential for increased dilution as mining nears the deposit limits. The use of shanty back design could be useful in addressing this issue.

 

2. Adjust the mining methods to reduce the level of internal dilution. Trade-off studies will be required to assess all aspects of the methods.

 

3. Complete a trade-off study comparing the use of CRF in areas that are distant from the paste fill source requiring high water content for delivery and lowering the backfill quality.

 

4. Consider upgrading the mine’s underground data-communications capabilities by replacing the present leaky-feeder system with a Wi-Fi fibre-optic network or a 4G-LTE cellular network.

 

5. An upgraded communications system will permit implementing centralized control and monitoring of underground operations from a control room on surface. These centralized functions can include real-time tracking of personnel and equipment, telemetry, ventilation-on-demand, and closed-circuit television, among other applications.

 

6. With a wireless communications system, consider implementing automated and/or tele-remote technology to operate equipment from control stations on surface. The technology can be used for mucking stopes, mucking development headings, production drilling, crushing, and operating rockbreakers, among other applications. A significant benefit is that it allows many mining operations to continue during otherwise non-productive periods, including lunch breaks, shift changes, blasting times, and ventilating smoke.

 

1.1.2.3 Mineral Processing

 

1. Re-evaluate the potential benefits that may be derived from a geometallurgical model to determine if additional test work and further development of a geometallurgical model will provide more valuable information than what is already available from test work results.

 

2. Conduct flotation test work on ore samples representing the lower lead and zinc head grades anticipated towards the end of the LOM to provide information on recovery and concentrate quality for planning purposes.
 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

Technical Report Summary - January 29, 2021

 

            
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3. Continue investigations into development of processing conditions suitable for campaigning transition/supergene ore through the plant.

 

1.1.2.4 Environment, Permitting and Social Considerations

 

1. Continue identifying and comparing solutions for storing tailings for the remainder of the LOM.

 

2. Evaluate the long term environmental impacts of allowing the tailings valley runoff to pond against and seep through the Pahuaypite waste rock dump.

 

3. Continue with participatory monitoring of water quality and implement social commitments to help improve access to water and water quality in the area.

 

4. Sourcing local employment may be difficult with expanded and continued operations as Nexa has already reported that sourcing local employees has, at times, been challenging. Continue with commitments in educating, training, recruitment, and diversity targeted to the local workforce.

 

5. Improve social and employment policies and procedures by developing mechanisms to communicate the outcomes of the employee and community focused activities with stakeholders and the public, particularly with a focus on access to water and perception about water quality.

 

6. Confirm the basis for the community of Chavin’s categorization as an Indigenous group by the Ministry of Culture in 2020 and conduct a gap analysis with respect to its 2018 impact assessment studies to determine the need for additional socio-cultural studies focused on Indigenous Peoples. The categorization of the community of Chavin by the Ministry of Culture should be explicitly acknowledged in Nexa’s Social Management Plan and its sub-plans (Communications Plan, Social Concertation Plan, and Community Development Plan) modified accordingly.

 

1.1.2.5 Costs and Economic Analysis

 

1. Continuously monitor costs and lock in costs as soon as possible to eliminate economic uncertainty.

 

2. Continue efforts towards improving efficiencies and approaches to mining and development operations as opportunities arise in these areas.

 

1.2 Economic Analysis

 

The economic analysis contained in this Technical Report Summary is based on the Mineral Reserves, economic assumptions provided by Nexa, and the capital and operating costs as presented in Section 18 of this Technical Report Summary.

 

Nexa has a silver streaming agreement with Triple Flag Mining Finance Bermuda Ltd. (Triple Flag) on silver production from the Cerro Lindo Mine. Triple Flag has the rights to 65% of all payable silver, at a cost of 10% of the spot silver price (up to a total of 19.5 million ounces (Moz) Ag). After the total has been reached, currently anticipated to be in 2027, Triple Flag is entitled to 25% of payable silver.

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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1.2.1 Economic Criteria

 

1.2.1.1 Physicals

 

Mine life: 9 years (between 2021 and 2029):

 

Underground ore tonnes mined:                 52,101 kt

 

Cu grade: 0.61%

 

Zn grade: 1.44%

 

Pb grade: 0.20%

 

Ag grade: 21.2 g/t

 

Processed:

 

Total Ore Feed: 52,101 kt

 

Cu grade: 0.61%

 

Zn grade: 1.44%

 

Pb grade: 0.20%

 

Ag grade: 21.2 g/t

 

Contained Metal:

 

Cu: 319 kt

 

Zn: 748 kt

 

Pb: 106 kt

 

Ag: 35,472 koz

 

Average LOM Recoveries:

 

Cu recovery 86.9%

 

Zn recovery 88.3%

 

Pb recovery 70.0%

 

Ag in Cu recovery 39.9%

 

Ag in Zn recovery 6.0%

 

Ag in Pb recovery 28.9%

 

Recovered Metals:

 

Cu: 277 kt

 

Zn: 660 kt

 

Pb: 74 kt

 

Ag: 26,527 koz

 

Payable Metals:

 

Cu: 266.7 kt

 

Zn: 561.2 kt

 

Pb: 70.6 kt

 

Ag: 22,446 koz
 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

Technical Report Summary - January 29, 2021

 

            
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1.2.1.2 Revenue

 

Revenue is estimated based on the following LOM weighted average metal prices:

 

Cu price: US$6,458/t

 

Zn price: US$2,487/t

 

Pb price: US$1,987/t

 

Ag price - spot: US$17.01/oz

 

Net Revenue includes the benefit of Cerro Lindo’s zinc concentrate processed at Nexa’s Cajamarquilla (CJM) zinc refinery in Peru (61%) and Três Marias (TM) (35%) and Juiz de Fora (JF) (4%) zinc refineries in Brazil. This integration with Nexa’s internal refineries provides the benefit of additional US$150.34/t zinc selling price in average, and zinc smelting at cost (rather than at commercial third-party terms).

 

Logistics, Treatment and Refining charges:

 

LOM average Transportation/Logistics charges:

 

Cu concentrate: US$109.26/t concentrate

 

Zn concentrate: US$64.82/t concentrate (weighted average logistic integration cost with CJM, TM, and JF refineries)

 

Pb concentrate: US$108.75/t concentrate

 

Treatment Charges:

 

TC+RC Cu concentrate: US$112.35/t concentrate

 

TC Zn concentrate for export: US$238.91/t concentrate

 

TC Pb concentrate: US$201.16/t concentrate

 

Refined Zn weighted average conversion costs at CJM, TM, and JF refineries: US$443.10/t

 

Refining Charges:

 

Ag in Cu concentrate: US$0.50/oz

 

Ag in Pb concentrate: US$1.00/oz

 

NSR Revenue after Logistics, Treatment and Refining charges is US$3,076 million.

 

1.2.1.3 Capital Costs

 

LOM sustaining capital costs of US$154.8 million.

 

LOM working capital balance of US$117.7 million.

 

Closure costs of US$57.2 million were included at the end of the Mineral Reserves based LOM in year 2030.
 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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1.2.1.4 Operating Costs

 

LOM unit operating cost average of:

 

Mine Development:             US$4.44/t mined

 

Underground Mining:         US$15.18/t mined

 

Processing:                            US$11.95/t milled

 

G&A:                                      US$3.01/t milled

 

Total unit operating costs of US$34.58/t milled.

 

LOM operating costs of US$1,801 million.

 

1.2.1.5 Taxation and Royalties

 

Corporate tax rate in Peru is 29.50%.

 

Special Mining Tax (IEM/GEM) LOM average rate: 4.3%.

 

Mining royalties LOM average rate: 4.3%.

 

Employees participation: 8%.

 

SLR has relied on a Nexa taxation model for calculation of income taxes applicable to the cash flow.

 

1.2.2 Cash Flow Analysis

 

SLR developed a LOM after-tax cash flow model for the Cerro Lindo Mine to confirm the economics of the LOM plan. The model is based on Nexa’s TR Cerro Lindo 2020 Final2 model. The model does not take into account the following components:

 

Financing costs

 

Insurance

 

Overhead cost for a corporate office

 

The economic analysis confirmed that the Cerro Lindo Mineral Reserves are economically viable. The pre-tax NPV at a 9% discount rate is US$639 million and the after-tax NPV at a 9% discount is US$304 million.

 

A discounted cash flow summary is presented in Table 1-1. All costs are in Q4 2020 US dollars with no allowance for inflation.

 

Table 1-1:          Discounted Cash Flow Summary 

Nexa Resources S.A. – Cerro Lindo Mine

 

    Units   Total LOM
Production        
LOM   years   9
UG Production   '000 tonnes   52,101
Ag Grade   gr/t   21.2
Cu Grade   %   0.61%
Pb Grade   %   0.20%
Zn Grade   %   1.44%
Concentrate Production        
 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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    Units   Total LOM
Cu Concentrate   dmt   1,071,157
Pb Concentrate   dmt   116,434
Zn Concentrate   dmt   1,121,767
Recovered        
Ag   oz   26,526,801
Cu   tonnes   277,430
Pb   tonnes   74,308
Zn   tonnes   660,272
Metal Prices        
LOM average - Ag   US$/oz   17.05
LOM average -  Cu   US$/tonne   6,458
LOM average -  Pb   US$/tonne   1,987
LOM average -  Zn   US$/tonne   2,487
Cash Flow        
Gross Revenue   US$ million   3,718
Transport / TC-RC  Charges   US$ million   (642)
Royalties   US$ million   (184)
Net Revenue   US$ million   2,892
Operating Costs        
Mining Costs   US$ million   (1,022)
Processing Costs   US$ million   (623)
G&A   US$ million   (157)
Other Costs   US$ million   (25)
Operating Cash Flow   US$ million   1,065
Direct Capital Costs   US$ million   (19)
Sustaining Capital Costs   US$ million   (136)
Reclamation & Closure   US$ million   (57)
Change Working Capital   US$ million   118
Pre-Tax Net Cash Flow   US$ million   971
Taxes - Income Tax   US$ million   (407)
Taxes - IEM/GEM   US$ million   (73)
After-Tax Cashflow   US$ million   491
Project Economics        
 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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    Units   Total LOM
Pre-Tax        
Pre-tax NPV at 8%   US$ million   667
Pre-tax NPV at 9%   US$ million   639
Pre-tax NPV at 10%   US$ million   612
After-Tax        
After-Tax NPV at 8%   US$ million   319
After-Tax NPV at 9%   US$ million   304
After-tax NPV at 10%   US$ million   290

 

1.2.3 Sensitivity Analysis

 

SLR conducted cash flow sensitivity analyses on the after-tax NPV at a 9% discount rate, to identify project risks, using metal price, head grade, metallurgical recovery, capital costs and operating costs.

 

The Project after-tax NPV is most sensitive to metal prices, head grade, followed by operating costs, metallurgical recovery, and capital costs.

 

1.3 Technical Summary

 

1.3.1 Property Description and Location

 

The Mine is located in the Chavín District, Chincha Province, Ica Department of Peru, approximately 268 km southeast of Lima and 60 km from the coast. The approximate coordinates of the Mine are 392,780m E and 8,554,165m N, using the UTM_WGS84 datum.

 

The current access from Lima is via the Panamericana Sur highway to Chincha (180 km) and then via an unpaved dirt road (60 km) from Huamanpuquio up the river valley. The closest commercial airport is Jorge Chavez, at Callao, approximately 300 km northwest.

 

1.3.2 Land Tenure

 

Cerro Lindo consists of 68 mineral concessions covering an area of 43,750.19 ha, and one beneficiation concession covering an area of 518.78 ha. The concessions are located in the districts of Chavin, Lunahuana, San Juan de Yanac, Grocio Prado, Pueblo Nuevo and Pacaran, provinces of Chincha and Cañete, departments of Lima and Ica in Peru.

 

Nexa owns a total of 80.16% in the Mine that corresponds to the sum of Nexa’s direct interest in Nexa Resources Peru (0.17%) and Nexa’s indirect interest in Nexa Peru (80.06%) through its controlled company Nexa Resources Cajamarquilla S.A. (99.91%), and the remaining 19.76% are floating shares.

 

1.3.3 History

 

Artisanal-style mining of outcropping barite bodies for use by the oil industry began in the early 1960s. The Cerro Lindo deposit was discovered in 1967, during a colour anomaly reconnaissance program. Compañía Minera – Milpo S.A.A. (Milpo), a predecessor company to Nexa Peru, acquired the property in 1984. From 1984 to 2011, Milpo carried out geological mapping, geophysical surveys, geochemical sampling, drilling, and trenching over the property. property. A feasibility study was completed in 2002 and construction started in 2006. The Mine commenced production in 2007.

 
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To June 30, 2020, the Mine had produced a total of approximately 66.4 Mt of ore.

 

1.3.4 Geology and Mineralization

 

The Cerro Lindo deposit is located in a 30 km by 10 km northwest trending belt of marine volcano-sedimentary rocks of the Middle Albian to Senonian (mid-Cretaceous) Huaranguillo Formation, belonging to the Casma Group, which is located within Tertiary intrusions of the Coastal Batholith. The Huaranguillo Formation fills the Canete volcano-sedimentary basin, one of the several similar basins that form the Casma Metallotect at the western side of the Andean Cordillera Occidental. In addition to Cerro Lindo, the Casma Metallotect hosts a number of important volcanogenic massive sulphide (VMS) deposits, including Tambogrande, Perubar, Potrobayo, Totoral, Maria Teresa, Aurora Augusta, and Palma

 

The Cerro Lindo deposit is a Kuroko-type VMS deposit. Mineralization is hosted in a pyroclastic unit composed of ash and lapilli-type polymictic tuffs of the Huaranguillo Formation. The deposit comprises lens-shaped, massive and stringer zones composed of pyrite, sphalerite, galena, chalcopyrite, and barite. The mineralization has characteristic zoning from zinc-rich to pyrite-rich and associated sericitic-pyritic alteration.

 

The mineralization has been divided into 19 mining production areas, which are termed OB-1, OB-2, OB-2B, OB3-4, OB-5, OB-5B, OB-5C, OB-5D, OB-6, OB-6A, OB-6B, OB-6C, OB-7, OB-8, OB-9, OB-10, OB-11, OB-12, OB-13, and OB-14. The mineralized lenses exhibit an irregular elongated geometry, and their longest axis (nearly 500 m) has a northwest-southeast horizontal trend (azimuth 135°). The mineralized bodies are up to 300 m thick and 100 m wide and generally dip to the southwest at 65° on average.

 

1.3.5 Exploration Status

 

A total of 4,808 drill holes totalling 654,129.63 m, as of March 02, 2020, have been completed at Cerro Lindo since 1995. Exploration has been carried out systematically since 2007. The 2020 exploration program, including an additional 52 drill holes totalling 19,541.4 m as of December 31, 2020, confirmed the continuity of the mineralization at the OB-13 and OB-14 zones towards the northwest and also for OB-14 at depth towards the southeast, as well as the upper part of OB-5B between the 1750 and 1950 levels, with an average thickness of 15 m trending northeast. Future exploration priorities include deeper stratigraphic levels of known mineralized zones at Cerro Lindo, as well as Northwest Extension OB3-4 and OB-12, Cerro Lindo Southeast Extension, Pucasalla, Pucasalla East, Festejo, Ventanalloc, Patahuasi Millay, Orcocobre, Toldo Grande, Pucatoro, Toldo Chico, Chavin del Sur, Mesa Rumi, Festejo Norte, Festejo Sur, Puca Punta, Pucasalla Norte, OB-14 Upper and Pucasalla Sur targets. Exploration work planned for 2021 includes 35,100 m of diamond core drilling focused on defining Inferred Mineral Resources at six different targets (Pucasalla, OB-6, OB-5B, OB-12, OB-8, and Patahuasi Millay areas), an airborne geophysical versatile time domain electromagnetic (VTEM) survey for all the exploration targets, 1:2,000 scale geological surface mapping for Pucasalla, Pucatoro and Orcocobre, and a geochemical gas sampling survey. In addition to the exploration program, the mining geology team plans to drill an additional 48,000 m with a goal of upgrading Inferred Mineral Resources and for mine planning purpose.

 

1.3.6 Mineral Resources

 

The Mineral Resource estimate for the Cerro Lindo Mine, as of December 31, 2020, using all data available as of March 2, 2020 was completed by Cerro Lindo staff and reviewed by SLR.

 
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The Mineral Resource estimate was completed using Datamine Studio RM and Leapfrog Geo software. Wireframes for geology and mineralization were constructed in Leapfrog Geo based on geology sections, assay results, lithological information, underground mapping, and structural data. Assays were capped to various levels based on exploratory data analysis and then composited to 2.5 m lengths. Wireframes were filled with blocks sub-celled at wireframe boundaries. Blocks were interpolated with grade using the ordinary kriging (OK) and inverse distance cubed (ID3) interpolation algorithms. Block estimates were validated using industry standard validation techniques. Classification of blocks used distance-based and other criteria. The Mineral Resource estimate was reported using all the material within resource shapes generated in Deswik Stope Optimizer (DSO) software, satisfying the minimum mining size, continuity criteria, and using a net smelter return (NSR) cut-off value of US$33.56/t for SLS resource shapes and US$49.90/t for C&F resource shapes. NSR cut-off values for the Mineral Resources are based on a zinc price of US$1.30/lb, a lead price of US$1.02/lb, a copper price of US$3.37/lb, and a silver price of US$19.38/oz.

 

The SLR QP reviewed the Mineral Resource assumptions, input parameters, geological interpretation, and block modelling and reporting procedures, and is of the opinion that the Mineral Resource estimate is appropriate for the style of mineralization and that the block model is reasonable and acceptable to support the December 31, 2020 Mineral Resource estimate.

 

The Mineral Resource estimate for Cerro Lindo, as of December 31, 2020, is summarized in Table 1-2.

 

Mineral Resources have been classified in accordance with the definitions for Mineral Resources in S-K 1300, which are consistent with Canadian Institute of Mining, Metallurgy and Petroleum (CIM) Definition Standards for Mineral Resources and Mineral Reserves dated May 10, 2014 (CIM (2014) definitions).

 

Table 1-2:          Summary of Mineral Resources – December 31, 2020 

Nexa Resources S.A. – Cerro Lindo Mine

 

    Grade   Contained Metal
  Tonnage   Zinc   Lead   Copper   Silver   Zinc   Lead   Copper   Silver
Category   (Mt)   (%)   (%)   (%)   (g/t)   (000 t)   (000 t)   (000 t)   (000 oz)
Measured   4.40   2.00   0.20   0.67   19.61   87.80   8.86   29.38   2,774.11
Indicated   3.46   1.37   0.25   0.45   24.96   47.32   8.79   15.54   2,775.90
Total M+I   7.86   1.72   0.22   0.57   21.96   135.12   17.65   44.92   5,550.01
                                     
Inferred   8.71   1.28   0.35   0.33   31.23   111.12   30.59   29.10   8,747.99

 

Notes:

 

1. The definitions for Mineral Resources in S-K 1300 were followed for Mineral Resources which are consistent with CIM (2014) definitions.

2. Mineral Resources are reported on a 100% ownership basis. Nexa owns 80.16%.

3. Mineral Resources are estimated at a net smelter return (NSR) cut-off value of US$33.56/t for sub-level open stoping (SLS) and US$49.90/t for cut and fill (C&F).

4. Mineral Resources are estimated using average long term metal prices of Zn: US$2,869.14/t (US$1.30/lb), Pb: US$2,249.40/t (US$1.02/lb), Cu: 7,426.59/t (US$3.37/lb), and Ag: US$19.38/oz, and metallurgical recoveries are based on recovery curves derived from historical processing data.

5. A minimum mining width of 5.0 m and 4.0 m was used to create SLS and C&F resource shapes respectively.

6. Bulk density varies depending on mineralization domain.

7. Mineral Resources are exclusive of Mineral Reserves.
 
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8. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability.

9. Numbers may not add due to rounding.

 

The SLR QP is of the opinion that, with consideration of the recommendations summarized in this section, any issues relating to all relevant technical and economic factors likely to influence the prospect of economic extraction can be resolved with further work.

 

1.3.7 Mineral Reserves

 

The Mineral Reserves for Cerro Lindo were estimated using an NSR cut-off value of US$33.56/t processed for SLS, US$49.90/t processed for C&F stoping, and a minimum mining width of five and four metres respectively. Mineral Reserves to be mined from 2021 to 2029 were estimated at 52.1 million tonnes, grading 1.44% Zn, 0.20% Pb, 0.61% Cu, and 21 g/t Ag.

 

The Mineral Reserve estimate, as of December 31, 2020, is summarized in Table 1-3.

 

Table 1-3:          Summary of Mineral Reserves – December 31, 2020 

Nexa Resources S.A. – Cerro Lindo Mine

 

        Grade   Contained Metal
   

Tonnage 

  Zinc   Lead   Copper   Silver   Zinc   Lead   Copper   Silver
Category   (Mt)    (%)   (%)   (%)   (g/t)   (000 t)   (000 t)   (000 t)   (000 oz)
Proven   29.37   1.71   0.23   0.60   20.86   501.5   66.1   177.3   19,702
Probable   22.73   1.08   0.18   0.62   21.58   246.4   40.0   141.8   15,770
Total   52.10   1.44   0.20   0.61   21.17   747.9   106.1   319.1   35,472

 

Notes:

 

1. The definitions for Mineral Reserves in S-K 1300 were followed for Mineral Reserves which are consistent with CIM (2014) definitions.

2. Mineral Reserves are estimated at NSR cut-off values of US$33.56/t processed for SLS and US$49.90/t processed for C&F stoping. A number of incremental stopes (down to US$26.16/t NSR value) are included in the estimate.

3. Mineral Reserves are estimated using average long term metal prices of Zn: US$2,494.90/t (US$1.13/lb); Pb: US$1,956.00/t (US$0.89/lb); Cu: US$6,457.90/t (US$2.93/lb); Ag: US$16.85/oz with all costs in US dollars.

4. A minimum mining width of 5.0 m and 4.0 m was used for SLS stopes and C&F stopes respectively.

5. Bulk density varies depending on mineralization domain.

6. Numbers may not add due to rounding.

7. The Mineral Reserve estimate is reported on a 100% basis. Nexa owns 80.16%.

 

The SLR QP is not aware of any risk factors associated with, or changes to, any aspect, of the modifying factors such as mining, metallurgical, infrastructure, permitting, or other relevant factors that could materially affect the Mineral Reserve estimate.

 

1.3.8 Mining Method

 

At Cerro Lindo, the main mining method utilized is sub-level longhole stoping with sub-level intervals of up to 30 m in heights. The stoping follows a primary, secondary, and tertiary sequence and paste backfill is used to provide ground support after each sequence. The paste fill is distributed from surface via a pipeline system to the stope locations. C&F stoping is also used to recover sill pillars and areas requiring a conventional mining approach for effective results. The stopes are mucked with load-haul-dump (LHD) units and haul trucks deliver ore to the main underground crusher on the 1820 m level via the grizzlies. The ore is then conveyed to surface stockpiles followed by use of overland conveyors for final delivery to the process plant.

 
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1.3.9 Mineral Processing

 

The Cerro Lindo processing plant is located on a ridge adjacent to the mine at an altitude of 2,100 MASL to 2,200 MASL. The processing plant commenced operations in 2007 with a capacity of 5,000 tpd, however, it has since been expanded to a name-plate capacity of 21,000 tpd. The current LOM plan continues to 2029. Processing consists of conventional crushing, grinding, and flotation to produce separate copper, lead, and zinc concentrates. Tailings are thickened and filtered for use as backfill or trucked to the dry stack tailings storage facility.

 

Water is supplied from a reverse osmosis desalination plant located on the coast and is pumped 60 km to the mine site. This is sufficient to supply the requirements for make-up water and potable water (treated at the mine site). Most of the process water requirement is recovered from tailings thickening and filtration and is returned to water storage tanks at the processing plant. Approximately 90% of total tailings water is recovered and recycled to the processing plant as process water.

 

The Cerro Lindo concentrates contain low concentrations of deleterious elements and higher than average concentrations of the primary metals. Due to the combined lead and zinc content of the copper concentrate (approximately 4.8% to 5.6%), however, the concentrate attracts a small penalty of approximately US$2.00/t.

 

1.3.10 Project Infrastructure

 

The in-situ and operating infrastructure at Cerro Lindo includes the following:

 

An underground mine accessed by 15 portals.

 

An underground crusher and conveyance system to surface.

 

Surface ore stockpiles and waste dumps.

 

A 21,000 tpd processing plant.

 

Two dry-stack TSFs.

 

Main site power supply.

 

Site access roads.

 

Mine shops, offices, warehouse facilities.

 

Mine camps facilities.

 

Power to the mine is supplied via the National Grid. The overall site demand to sustain a production rate of 20,800 tpd is approximately 36.5 MW. The mine has a backup generator to support the main ventilation system.

 

There is no fresh water withdrawal from natural water bodies at the mine site, and the mine obtains very little water from the underground mine workings. Approximately 40% of total demand is extracted from five local groundwater wells/boreholes. The remaining 60% of industrial fresh water is supplied from a desalination plant located on the coast.

 

Tailings from the process plant are thickened to two streams. Approximately 50% of the tailings are further thickened and used for paste fill and the other 50% is sent to the Pahuaypite 1 and 2 dry stacks. Pahuaypite 1 has been approved for a 10% expansion and a plan is in place for a similar expansion at Pahuaypite 2.

 
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Waste rock from the underground mining operations is either used as backfill underground or stockpiled on the surface. There are currently six locations on surface for waste rock stockpiling with a combined capacity of 6.7 Mm3.

 

1.3.11 Market Studies

 

The principal commodities that are produced at the Cerro Lindo mine – zinc, copper, lead, and silver – are freely traded at prices and terms that are widely known so that prospects for sale of any production are virtually assured. Cerro Lindo is an operating mine with concentrate sales contracts in place for copper and lead concentrates, with the main players in the world, between global traders and refineries. Zinc concentrate is consumed by Nexa’s Cajamarquilla, Três Marias, and Juiz de Fora smelters according to their internal planning.

 

Market information is based on the industry scenario analysis prepared by Nexa’s Market Intelligence team in July 2020 using information sourced from different banks and independent financial institutions.

 

1.3.12 Environmental, Permitting, and Social Considerations

 

The geographical area where the Cerro Lindo facilities are located is arid, characterized by very low precipitation and high evaporation. Water conservation is a primary objective in Cerro Lindo due to the limited water availability in the area. Water is recycled from ore processing and re-used as much as possible. Nexa operates Cerro Lindo with a zero-discharge commitment for industrial and domestic water. Industrial fresh water is supplied from a desalination plant located at the coast to meet water requirements for mine operation activities. There is no fresh water withdrawal from natural water bodies at the mine site. Approximately 60% of the total fresh water supply to the mine site is taken from the ocean with approximately 40% taken from groundwater wells.

 

Tailings from the process plant are thickened and then further dewatered in either the paste plant to be deposited underground, or to the filter plant to the south of the processing plant to be filtered and subsequently placed in two dry-stack storage facilities, Pahuaypite 1 and Pahuaypite 2. As much as 90% of the process water from dewatered tailings is recycled with industrial fresh water being supplied from a desalination plant at the coast to meet site and process water make-up requirements. The mine site operates with a zero-water discharge commitment.

 

The most recent modification of the Environmental Impact Assessment (EIA) was approved by the Peruvian authorities in 2018 to grant authorization for a maximum production rate of 22,500 tpd. Cerro Lindo has an EMP, which addresses mitigation measures and monitoring programs for industrial and domestic effluent discharges, surface water quality and sediment, groundwater quality, surface flow, air quality (particulate matter and gas emissions), non-ionizing radiation, noise, vibrations, soil quality, terrestrial and aquatic flora, terrestrial and aquatic fauna. The most recent update of the environment plan was presented in the 2018 EIA.

 

Cerro Lindo holds a number of permits in support of the current operations. The permits are Directorial Resolutions issued by the Peruvian authorities upon approval of mining environmental management instruments filed by the mining companies. Nexa maintains and up to date record of the legal permits obtained to date.

 
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Nexa adheres to international standards to provide best practices for public reporting on economic, environmental, and social impacts in order to help Nexa and its shareholders and stakeholders understand their corporate contribution to sustainable development. Corporately, Nexa has made several commitments to improve community health and safety as well as the overall well-being of community members.

 

A formal Mine Closure Plan was prepared in 2009 for the mine components within the context of the Peruvian legislation and has subsequently been amended or updated four times. The Closure Plan addresses temporary, progressive and final closure actions, and post closure inspection and monitoring. Progressive closure will continue taking place until 2027, final Closure is planned for 2028 and 2029, and post-closure monitoring will take place between 2030 and 2034. A closure cost estimate was developed and included in the Mine Closure Plans. The total financial assurance for progressive closure, final closure and post-closure is calculated by Nexa according to the Peruvian regulations (Supreme Decree D.S. N° 262-2012-MEM/DM).

 

1.3.13 Capital and Operating Cost Estimates

 

The capital costs for the Mine are shown in Table 1-4. Cerro Lindo is an operating mine hence all capital costs are considered sustaining cost.

 

Table 1-4:          Sustaining Capital Cost 

Nexa Resources S.A. – Cerro Lindo Mine

 

Description   Total (US$000)   2021   2022   2023   2024   2025   2026   2027   2028   2029   2030
Mine Development   66,275   20,326   16,768   15,903   3,722   9,556   -   -   -   -   -
Equipment Replacement   32,410   3,744   5,136   5,195   8,860   6,651   2,824   -   -   -   -
Other Sustaining   37,547   8,649   6,630   (492)   7,737   3,096   1,910   3,339   3,339   3,339   -
Tailings / Dumps   9,246   3,082   664   5,500   -   -   -   -   -   -   -
Modernization   9,364   3,760   4,779   525   205   95   -   -   -   -   -
Sub-Total   154,842   39,561   33,977   26,631   20,524   19,398   4,734   3,339   3,339   3,339   -
Closure   57,157   -   -   -   -   -   -   -   -   -   57,157
Total   211,999   39,561   33,977   26,631   20,524   19,398   4,734   3,339   3,339   3,339   57,157

 

The operating costs for Cerro Lindo are shown in Table 1-5.

 
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Table 1-5: Mine Operating Cost Estimate 

Nexa Resources S.A. – Cerro Lindo Mine

 

Description   Total LOM (US$M)   Average
(US$M/yr)
  LOM Unit Cost
(US$/t)
UG Mining   791   88   15.18
Mine Development   231   26   4.44
Processing   623   69   11.95
G&A   157   17   3.01
Total   1,802   200   34.58

 
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2.0 Introduction

 

SLR Consulting Ltd (SLR) was retained by Nexa Resources S.A. (Nexa) to prepare an independent Technical Report Summary on the Cerro Lindo Mine (Cerro Lindo or the Mine), located in the Department of Ica, Peru. The purpose of this report is to support the Mineral Resource and Mineral Reserve estimates for the Mine as of December 31, 2020. This Technical Report Summary conforms to United States Securities and Exchange Commission (SEC) Modernized Property Disclosure Requirements for Mining Registrants as described in Subpart 229.1300 of Regulation S-K, Disclosure by Registrants Engaged in Mining Operations (S-K 1300) and Item 601 (b)(96) Technical Report Summary. SLR visited the property from June 4 to 7 and June 18 to 20, 2019.

 

Nexa is a publicly traded company on the Toronto Stock Exchange (TSX) and the New York Stock Exchange (NYSE). It is a reporting issuer in all provinces and territories of Canada.

 

Nexa is a large-scale, low-cost, integrated zinc producer with over 60 years of experience developing and operating mining and smelting assets in Latin America. Nexa has a diversified portfolio of polymetallic mines (zinc, lead, copper, silver, and gold) and also greenfield projects at various stages of development in Brazil and Peru. In Brazil, Nexa owns and operates two underground mines, Vazante and Morro Agudo (Zn and Pb). It also operates two zinc smelters in Brazil (Três Marias and Juiz de Fora). In Peru, Nexa operates the El Porvenir (Zn, Pb, Cu, and Ag), Cerro Lindo (Zn, Cu, Pb, and Ag), and Atacocha (Zn, Cu, Pb, Au, and Ag) mines, as well as the Cajamarquilla zinc smelter near Lima. Nexa’s development projects in Peru include Magistral, Shalipayco, Florida Canyon (JV with Solitario), Hilarión, and Pukaqaqa. In Brazil, Nexa is developing the Aripuanã Zinc Project (Zn, Pb, Cu, Au, and Ag), which is currently under construction.

 

Cerro Lindo is located in the Chavín District, Chincha Province, Ica Department of Peru, approximately 268 km southeast of Lima. Nexa owns a total of 80.16% in the Mine that corresponds to the sum of Nexa’s direct interest in Nexa Resources Peru S.A.A. (Nexa Peru) (0.17%) and Nexa’s indirect interest in Nexa Peru (80.06%) through its controlled company Nexa Resources Cajamarquilla S.A. (99.91%), and the remaining 19.76% are floating shares. Cerro Lindo commenced operations in 2007 and comprises an underground zinc-lead-copper-silver mine, a conventional comminution flotation process plant, a coastal desalination plant, and associated infrastructure. The Mine produces separate zinc, lead, and copper concentrates with silver content. In 2020, the Mine produced 105,876 tonnes (t) of zinc, 32,499 t of copper, 15,688 t of lead, and 4,254,239 ounces (oz) of silver. As of December 2020, the Mine is scheduled to produce a total of approximately 52 million tonnes (Mt) over a mine life of nine years.

 

2.1 Site Visits

 

SLR visited the Mine from June 4 to 7, 2019. During the site visit, SLR Qualified Persons (QP) reviewed plans and sections, visited the core shack, examined drill holes and mineralized underground exposures, reviewed core logging and quality assurance and quality control procedures and database management system, inspected the underground operations, the processing plant, the chemical laboratory and the surface and underground infrastructure and held discussions with Nexa personnel.

 

Subsequent to this visit, SLR visited the Mine from June 18 to 20, 2019. The purpose of the second visit was to conduct a site reconnaissance from an environmental perspective focusing on the tailings storage facilities, the water management ponds and environmental features such as the Topará Creek, and hold discussions with the Environment Manager and the Community Relations Manager at Cerro Lindo.

 
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2.2 Sources of Information

 

During the preparation of this report and the site visit, discussions were held with the following personnel from Nexa:

 

Thiago Nantes Teixeira, Mineral Resources and Mineral Reserves Committee

Priscila Artioli, Mineral Resources and Mineral Reserves Committee

Jose Antonio Lopes, Corporate Resource Manager

Jerry Huaman, Resource Manager, Nexa Peru

Jhonatan Lopez Alvarez, Modeller Geologist at Cerro Lindo

Thomas Lafayette, Database Administrator Manager

Charlton Villantoy Fajardo, Database Administrator at Cerro Lindo

Jean Paul Bueno, Geology Manager at Cerro Lindo

Edwars Espinoza Jara, Mine Chief Geologist

Mervin Tapia, Brownfield Exploration Manager at Cerro Lindo

Fernando Madeira Perisse, Technical Services Manager

Paulo Henrique Araujo Calazans, Mining Engineer

Souto Padron Antonio, General Manager at Cerro Lindo

Rui Carlos Sorrentino Carboni, Short Term Planner at Cerro Lindo

Hilario Gorvenia, Metallurgical Plant Manager at Cerro Lindo

Cecilia Pastor, Land and Mineral Rights Manager, Nexa Peru

Pablo Peña, Land and Mineral Rights GIS, Nexa Peru

Gladys Ruiz, Environment Manager at Cerro Lindo

Jose Neira Araoz, Community Relations Chief at Cerro Lindo.

Renato Piazzon, Corporate Legal Counsel, Nexa Peru

 

This Technical Report Summary was prepared by SLR QPs. The documentation reviewed, and other sources of information, are listed at the end of this report in Section 24 References.

 
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2.3 List of Abbreviations

 

Units of measurement used in this report conform to the metric system. All currency in this report is US dollars (US$) unless otherwise noted.

 

µ micron kVA kilovolt-amperes
µg microgram kW kilowatt
a annum kWh kilowatt-hour
A ampere L litre
bbl barrels lb pound
Btu British thermal units L/s litres per second
°C degree Celsius m metre
C$ Canadian dollars M mega (million); molar
cal calorie m2 square metre
cfm cubic feet per minute m3 cubic metre
cm centimetre MASL metres above sea level
cm2 square centimetre m3/h cubic metres per hour
d day mi mile
dia diameter min minute
dmt dry metric tonne µm micrometre
dwt dead-weight ton mm millimetre
°F degree Fahrenheit mph miles per hour
ft foot MVA megavolt-amperes
ft2 square foot MW megawatt
ft3 cubic foot MWh megawatt-hour
ft/s foot per second oz Troy ounce (31.1035 g)
g gram oz/t ounce per tonne
G giga (billion) ppb part per billion
Gal Imperial gallon ppm part per million
g/L gram per litre psia pound per square inch absolute
Gpm Imperial gallons per minute psig pound per square inch gauge
g/t gram per tonne RL relative elevation
gr/ft3 grain per cubic foot s second
gr/m3 grain per cubic metre st short ton
ha hectare stpa short ton per year
hp horsepower stpd short ton per day
hr hour t metric tonne
Hz hertz tpa metric tonne per year
in. inch tpd metric tonne per day
in2 square inch US$ United States dollar
J joule USg United States gallon
k kilo (thousand) USgpm US gallon per minute
kcal kilocalorie V volt
kg kilogram W watt
km kilometre wmt wet metric tonne
km2 square kilometre wt% weight percent
km/h kilometre per hour yd3 cubic yard
kPa kilopascal yr year
 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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3.0 Property Description

 

3.1 Location

 

The Mine is located in the Chavín District, Chincha Province, Ica Department of Peru, approximately 268 km southeast of Lima and 60 km from the coast (Figure 3-1). The approximate coordinates of the Mine are 392,780m E and 8,554,165m N, using the UTM_WGS84 datum.

 

3.2 Land Tenure

 

Mineral rights in Peru include mineral concessions and mineral claims. A mineral claim is an application to obtain a mineral concession.

 

Cerro Lindo consists of 68 mineral concessions covering an area of 43,750.19 ha, and one beneficiation concession covering an area of 518.78 ha. The concessions are located in the districts of Chavin, Lunahuana, San Juan de Yanac, Grocio Prado, Pueblo Nuevo and Pacaran, provinces of Chincha and Cañete, departments of Lima and Ica in Peru.

 

The relevant mineral rights information, including the code number and concession name, titleholder, status, registration date and number, and available area for each of the mineral concessions, can be found in Table 3-1 (Nexa, 2020a) and is shown in Figure 3-2, and for the beneficiation concession in Table 3-2. Nos. 65 to 68 mineral concession titles were granted to Nexa in Q4 2020 after the release of legal opinion (Nexa, 2020a).

 

Nexa owns a total of 80.16% in the Mine that corresponds to the sum of Nexa’s direct interest in Nexa Resources Peru S.A.A. (Nexa Peru) (0.17%) and Nexa’s indirect interest in Nexa Peru (80.06%) through its controlled company Nexa Resources Cajamarquilla S.A. (99.91%), and the remaining 19.76% are floating shares.

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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Table 3-1:                     Cerro Lindo Mineral Rights

Nexa Resources S.A. – Cerro Lindo Mine

 

No.

Concession
Code

Concession
Name

Titleholder

Status*

Date

Public Registry
Record**

Area (ha)

1 10009257X02 Febrero 1979 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 109 13/02/1979 P-02026393 998.77
2 10000049Y01 Cerro Lindo Nexa Resources Peru S.A.A. D.M. Titulado D.L. 109 15/06/1967 P-02018851 998.77
3 010210100 Cerro Lindo 12 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 10/11/2000 P-13596017 15.24
4 010210100A Cerro Lindo 12-B Fraccionado Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 10/11/2000 P-13616219 0.83
5 010210200 Cerro Lindo 13 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 10/11/2000 P-12695744 10.54
6 010377204 Cerro Lindo 14 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 07/12/2004 P-12528871 999.43
7 010377104 Cerro Lindo 15 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 07/12/2004 P-12528882 200.00
8 010488308 Cerro Lindo 17 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 19/08/2008 P-12525671 100.00
9 010430411 Cerro Lindo 18 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 11/08/2011 P-13600117 232.39
10 010273015 Cerro Lindo 19 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 16/07/2015 P-13927075 747.78
11 010273115 Cerro Lindo 20 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 16/07/2015 P-14063670 568.37
12 010273215 Cerro Lindo 21 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 16/07/2015 P-13925791 493.75
13 010273315 Cerro Lindo 22 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 16/07/2015 P-13927144 300.00
14 010273415 Cerro Lindo 23 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 16/07/2015 P-13611414 602.28
15 010273515 Cerro Lindo 24 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 16/07/2015 P-13927140 660.90
16 010273615 Cerro Lindo 25 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 16/07/2015 P-13926206 786.09
17 010273715 Cerro Lindo 26 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 16/07/2015 P-14420944 1,000.00
18 010273815 Cerro Lindo 27 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 16/07/2015 P-14418565 500.00
19 010273915 Cerro Lindo 28 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 16/07/2015 P-14420320 500.00
 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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No.

Concession
Code

Concession
Name

Titleholder

Status*

Date

Public Registry
Record**

Area (ha)

20 010021518 Cerro Lindo 29 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 03/01/2018   549.36
21 010021818 Cerro Lindo 32 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 03/01/2018 P-14410200 669.70
22 010021918 Cerro Lindo 33 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 03/01/2018   626.40
23 010022118 Cerro Lindo 35 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 03/01/2018   477.82
24 010022318 Cerro Lindo 37 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 03/01/2018 P-14418651 704.14
25 010022518 Cerro Lindo 38 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 03/01/2018 P-14418719 825.41
26 010022418 Cerro Lindo 39 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 03/01/2018 P-14419450 320.12
27 010022618 Cerro Lindo 40 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 03/01/2018 P-14419449 652.70
28 010022718 Cerro Lindo 41 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 03/01/2018 P-14417939 836.83
29 010022918 Cerro Lindo 42 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 03/01/2018 P-14417892 563.17
30 010022818 Cerro Lindo 43 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 03/01/2018 P-14419494 416.12
31 010023018 Cerro Lindo 44 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 03/01/2018 P-14420266 591.77
32 010023118 Cerro Lindo 45 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 03/01/2018 P-14417945 900.00
33 010023218 Cerro Lindo 46 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 03/01/2018 P-14420941 1,000.00
34 010023418 Cerro Lindo 47 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 03/01/2018 P-14420268 1,000.00
35 010023518 Cerro Lindo 48 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 03/01/2018 P-14417884 670.05
36 010153218 Cerro Lindo 49 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 02/05/2018   481.64
37 010153118 Cerro Lindo 50 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 02/05/2018   524.60
38 010209200 Cerro Lindo 5 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 09/11/2000 P-13613580 900.00
39 010209300 Cerro Lindo 6 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 09/11/2000 P-13616230 875.97
40 010051313 Checho 500 M Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 02/01/2013 P-13611454 481.15
41 010051213 Checho 700 M Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 02/01/2013 P-13613538 700.00
 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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No.

Concession
Code

Concession
Name

Titleholder

Status*

Date

Public Registry
Record**

Area (ha)

42 010167797 Contopa 44 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 17/04/1997 P-02031014 300.00
43 11025895X01 Festejo 1 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 109 14/03/1990 P-02027481 1,000.00
44 10011858X01 Festejo 10 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 109 14/03/1990 P-02027470 1,000.00
45 11025896X01 Festejo 2 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 109 14/03/1990 P-02027476 1,000.00
46 11025897X01 Festejo 3 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 109 14/03/1990 P-02027477 1,000.00
47 010938595 Festejo 30 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 04/12/1995 P-02029871 875.59
48 11025899X01 Festejo 5 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 109 14/03/1990 P-02027479 1,000.00
49 10011854X01 Festejo 6 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 109 14/03/1990 P-02027468 1,000.00
50 10011855X01 Festejo 7 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 109 14/03/1990 P-02027482 1,000.00
51 10011856X01 Festejo 8 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 109 14/02/1990 P-02027469 1,000.26
52 010174812 Festejo 9 M Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 02/05/2012 P-13615927 800.00
53 010225414 Julia I M Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 02/05/2014 P-13595461 400.00
54 010225614 Kala I M Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 02/05/2014 P-13613582 200.00
55 010225514 Kala M Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 02/05/2014 P-13613554 100.00
56 010432706 Mariale Segunda Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 13/10/2006 P-12086766 900.00
57 010104614 Nuevo Horizonte 2008 M Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 02/01/2014 P-13613581 230.34
58 010225714 Ponciana 1 M Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 02/05/2014 P-13615933 400.00
59 010140608 VM 142 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 07/02/2008 P-12956960 1,000.00
60 010140708 VM 143 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 07/02/2008 P-12959327 400.00
61 010354306 VM 21 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 15/08/2006 P-12177428 1,000.00
62 010354406 VM 22 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 15/08/2006 P-12178991 500.00
 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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No.

Concession
Code

Concession
Name

Titleholder

Status*

Date

Public Registry
Record**

Area (ha)

63 010688808 VM 278 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 18/12/2008 P-12955719 799.03
64 010035609 VM 282 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 02/02/2009 P-12956175 100.00
65 010021618 Cerro Lindo 30 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 3/01/2018   891.77
66 010021718 Cerro Lindo 31 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 3/01/2018   759.31
67 010022018 Cerro Lindo 34 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 3/01/2018   626.57
68 010022218 Cerro Lindo 36 Nexa Resources Peru S.A.A. D.M. Titulado D.L. 708 3/01/2018   655.28

 

Source: Nexa, 2020a

 

Notes.

* All concessions are mineral concessions. Nos. 65 to 68 mineral concessions titles were granted in Q4 of 2020 after the release of Nexa, 2020a.

**Some of the records are being updated by the National Office of the Superintendent of Public Registers (SUNARP).

 

Table 3-2:                 Cerro Lindo Beneficiation Concession 

Nexa Resources S.A. – Cerro Lindo Mine

 

No.

Project

Code

Concession

Holder

Date

Granted Area (ha)

District

Province

Department

1 Mina Cerro Lindo P0000506 Cerro Lindo Nexa Resources Peru S.A.A. 10/10/2006 518.7800 Chavín Chincha Ica
 
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Figure 3-1: Mine Location 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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Figure 3-2: Land Tenure 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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Pursuant to information provided by the Peruvian Institute of Geology, Mining and Metallurgy (INGEMMET), there are four archaeological sites overlapping with the Cerro Lindo concession (10000049Y01): Frente Pahuaypite (10,480.35 m2), Pahuaypite Bajo Sector 2 (1,047.42 m2), Pahuaypite Bajo (12,842.43 m2) and Patahuasi (Area: 21,573.39 m2). Exploration and/or mining activities in the area overlapping the archaeological sites are carried out under the Certificate of Non-existence of Archaeological Remains (CIRA) No. 2007-253.

 

3.2.1 Mineral Rights

 

The term “mineral rights” refers to mineral concessions and mineral claims. Other rights under the General Mining Law, such as beneficiation concessions, mineral transportation concessions, and general labour concessions are not considered under said term.

 

According to Peruvian General Mining Law (the Law):

 

a. Mineral concessions grant their holder the right to explore, develop, and mine metallic or non-metallic minerals located within their internal boundaries.

 

b. A mineral claim is an application to obtain a mineral concession. Exploration, development, and exploitation rights are obtained once title to concession has been granted, except in those areas that overlap with pre-existing claims or concessions applied for before December 15, 1991. Upon completion of the title procedure, resolutions awarding title must be recorded with the Public Registry to create enforceability against third parties and the State.

 

c. Mineral rights are separate from surface rights. They are freely transferable.

 

d. A mineral concession by itself does not authorize to carry out exploration or exploitation activities, but rather the titleholder must first:

 

(i) Obtain approval from the Culture Ministry of the applicable archaeological declarations, authorizations, or certificates.

 

(ii) Obtain the environmental certification issued by the competent environmental authority, subject to the rules of public participation.

 

(iii) Obtain permission for the use of land (i.e., obtain surface rights) by agreement with the owner of the land or the completion of the administrative easement procedure, in accordance with the applicable regulation.

 

(iv) Obtain the applicable governmental licences, permits, and authorizations, according to the nature and location of the activities to be undertaken.

 

(v) Carry out consultations with Indigenous Peoples under the Culture Ministry, should there be any communities affected by potential exploitation of the mineral concession, as per International Labour Organization (ILO) Convention 169.

 

e. Mineral rights holders must comply with the payment of an annual fee equal to $ 3.00 per hectare per year, on or before June 30 of each year.

 

f. Holders of mineral concessions must meet a Minimum Annual Production Target or spend the equivalent amount in exploration or investments before a statutory deadline. When such deadline is not met, a penalty must be paid as described below:

 

Mineral concessions must meet a statutory Minimum Annual Production Target of 1 Tax Unit (Unidad Impositiva Tributaria, or UIT) per hectare per year for metallic concessions, within a statutory term of ten years since the concession is titled. The applicable penalty is 2% of the Minimum Annual Production Target per hectare per year as of the 11th year until the 15th year. Starting in the 16th year and until the 20th year, the applicable penalty is 5% of the Minimum Annual Production Target per year, and starting in the 21st year and until the 30th year the applicable penalty is 10% of the Minimum Annual Production Target per year. After the 30th year, if the Minimum Annual Production Target is not met, the mining concession will lapse automatically.

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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g. Mineral concessions may not be revoked as long as the titleholder complies with the Good Standing Obligations according to which mineral concessions will lapse automatically if any of the following events take place:

 

(i) The annual fee is not paid for two years.

 

(ii) The applicable penalty is not paid for two consecutive years.

 

(iii) A concession expires if it does not reach the minimum production in the year 30, and cannot justify the non-compliance up to five additional years due to reasons of force majeure described in the current legislation.

 

h. Agreements involving mineral rights (such as an option to acquire, a mining lease or the transfer of a mineral concession) must be formalized through a deed issued by a public notary and must be recorded with the Public Registry to create enforceability against third parties and the Peruvian State.

 

3.2.2 Beneficiation Concession

 

According to Peruvian General Mining Law (the Law):

 

a. The beneficiation concession grants the right to use physical, chemical, and physical-chemical processes to concentrate minerals or purify, smelt, or refine metals.

 

b. As from the year in which the beneficiation concession was requested, the holder shall be obliged to pay the Mining Concession Fee in an annual amount according to its installed capacity, as follows:

 

(i) 350 tpd or less: 0.0014 of one UIT per tpd.

 

(ii) from more than 350 tpd to 1,000 tpd: 1.00 UIT

 

(iii) from 1,000 tpd to 5,000 tpd: 1.5 UIT

 

(iv) for every 5,000 tpd in excess: 2.00 UIT

 

(v) “tpd” refers to the installed treatment capacity. In the case of expansions, the payment that accompanies the application is based on the increase in capacity.

 

3.2.3 Annual Fees and Penalties

 

Pursuant to Table 3-1 and Table 3-2, all annual fees applicable to the mineral concessions, mineral claims, and beneficiation concession comprising the Mine have been paid in full up to and including year end 2020, as detailed in Table 3-3.

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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Table 3-3:                    Annual Fee per Mineral Right and Beneficiation Concession – 2020

Nexa Resources S.A. – Cerro Lindo Mine

 

Concession
Code

Concession
Name

2020 Annual Fee
(US$)

2020
Penalty
(US$)

2020Total
Payment
(US$)

1 10009257X02 Febrero 1979 2,996.31 24,388.56* 2,996.31
2 10000049Y01 Cerro Lindo 2,996.31 24,388.55* 2,996.31
3 010210100 Cerro Lindo 12 45.72 372.13* 45.72
4 010210100A Cerro Lindo 12-B Fraccionado 2.5 20.32* 2.5
5 010210200 Cerro Lindo 13 31.61 257.26* 31.61
6 10011858X01 Festejo 10 2,999.99 24,418.53* 2,999.99
7 10011854X01 Festejo 6 3,000.00 24,418.60* 3,000.00
8 10011855X01 Festejo 7 3,000.00 24,418.60* 3,000.00
9 10011856X01 Festejo 8 3,000.78 24,424.92* 3,000.78
10 010209200 Cerro Lindo 5 2,700.00 21,976.74 24,676.74
11 010209300 Cerro Lindo 6 2,627.93 21,390.09 24,018.02
12 11025895X01 Festejo 1 3,000.00 24,418.60 27,418.60
13 11025896X01 Festejo 2 2,999.99 24,418.53 27,418.52
14 11025897X01 Festejo 3 3,000.00 24,418.63 27,418.63
15 010938595 Festejo 30 2,626.76 21,380.59 24,007.35
16 11025899X01 Festejo 5 3,000.00 24,418.60 27,418.60
17 010377204 Cerro Lindo 14 2,998.30 2,440.47 5,438.77
18 010377104 Cerro Lindo 15 600 488.37 1,088.37
19 010488308 Cerro Lindo 17 300 2,441.86 2,741.86
20 010430411 Cerro Lindo 18 697.18 ** 697.18
21 010273015 Cerro Lindo 19 2,243.34 ** 2,243.34
22 010273115 Cerro Lindo 20 1,705.10 ** 1,705.10
23 010273215 Cerro Lindo 21 1,481.24 ** 1,481.24
24 010273315 Cerro Lindo 22 900 ** 900
25 010273415 Cerro Lindo 23 1,806.85 ** 1,806.85
26 010273515 Cerro Lindo 24 1,982.71 ** 1,982.71
27 010273615 Cerro Lindo 25 2,358.28 ** 2,358.28
28 010273715 Cerro Lindo 26 3,000.00 ** 3,000.00
29 010273815 Cerro Lindo 27 1,500.00 ** 1,500.00
30 010273915 Cerro Lindo 28 1,500.00 ** 1,500.00
 
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Concession
Code

Concession
Name

2020 Annual Fee
(US$)

2020
Penalty
(US$)

2020Total
Payment
(US$)

31 010021518 Cerro Lindo 29 1,648.04 ** 1,648.04
32 010021618 Cerro Lindo 30 2,700.00 ** 2,700.00
33 010021718 Cerro Lindo 31 3,000.00 ** 3,000.00
34 010021818 Cerro Lindo 32 2,009.06 ** 2,009.06
35 010021918 Cerro Lindo 33 2,700.00 ** 2,700.00
36 010022018 Cerro Lindo 34 3,000.00 ** 3,000.00
37 010022118 Cerro Lindo 35 1,433.42 ** 1,433.42
38 010022218 Cerro Lindo 36 3,000.00 ** 3,000.00
39 010022318 Cerro Lindo 37 2,112.41 ** 2,112.41
40 010022518 Cerro Lindo 38 2,476.19 ** 2,476.19
41 010022418 Cerro Lindo 39 960.36 ** 960.36
42 010022618 Cerro Lindo 40 1,958.09 ** 1,958.09
43 010022718 Cerro Lindo 41 2,510.45 ** 2,510.45
44 010022918 Cerro Lindo 42 1,689.50 ** 1,689.50
45 010022818 Cerro Lindo 43 1,248.35 ** 1,248.35
46 010023018 Cerro Lindo 44 1,775.28 ** 1,775.28
47 010023118 Cerro Lindo 45 2,700.00 ** 2,700.00
48 010023218 Cerro Lindo 46 3,000.00 ** 3,000.00
49 010023418 Cerro Lindo 47 3,000.00 ** 3,000.00
50 010023518 Cerro Lindo 48 3,000.00 ** 3,000.00
51 010153218 Cerro Lindo 49 1,800.00 ** 1,800.00
52 010153118 Cerro Lindo 50 2,100.00 ** 2,100.00
53 010051313 Checho 500 M 1,443.46 ** 1,443.46
54 010051213 Checho 700 M 2,100.00 ** 2,100.00
55 010167797 Contopa 44 900 7,325.58 8,225.58
56 010174812 Festejo 9 M 2,399.99 ** 2,399.99
57 010225414 Julia I M 1,200.00 ** 1,200.00
58 010225614 Kala I M 600 ** 600
59 010225514 Kala M 300 ** 300
60 010432706 Mariale Segunda 2,700.00 21,976.74 24,676.74
61 010104614 Nuevo Horizonte 2008 M 691.02 ** 691.02
62 010225714 Ponciana 1 M 1,200.00 ** 1,200.00
63 010140608 Vm 142 3,000.00 24,418.60 27,418.60
 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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Concession
Code

Concession
Name

2020 Annual Fee
(US$)

2020
Penalty
(US$)

2020Total
Payment
(US$)

64 010140708 Vm 143 1,200.00 9,767.44 10,967.44
65 010354306 Vm 21 3,000.00 24,418.60 27,418.60
66 010354406 Vm 22 1,500.00 12,209.30 13,709.30
67 010688808 VM 278 2,397.10 19,511.30 21,908.40
68 010035609 VM 282 300 2,441.86 2,741.86
69 P0000506 Cerro Lindo (Beneficiation Concession) 11,237.50 ** 11,237.50

 

Source: Nexa, 2020a

 

Notes. 

*No penalty, achieved minimum annual production

**Not affected by penalty, within the statutory term of ten years

Exchange rate of 3.44 PEN/ USO based on SUNAT Exchange Rate as of May 29, 2020.

 

Certain mineral concessions comprising the Mine are subject to a penalty since the minimum required levels of production or exploration expenditures have not been met as stated in the previous subsection (Mineral Rights). The minimum annual production is equal to 1 Tax Unit (UIT) per granted hectare; the minimum annual investment is the penalty to be paid multiplied by 10. All penalties applicable to the mineral concessions comprising the Mine, have been paid as indicated in Table 3-3. The penalties on concessions included in the Administrative Economic Unit (UEA) Cerro Lindo (Nos. 1 through 9 in Table 3-3) are not due because the Minimum Annual Production Target was met for these concessions. The penalty amounts shown for these concessions represent the annual amounts that would be payable if the Minimum Annual Production Target was not met.

 

3.2.4 Recorded Liens and Encumbrances

 

Pursuant to the information gathered from the Public Registry, Nexa (2020a) reports that there are no liens and encumbrances.

 

3.3 Surface Rights and Easements

 

According to the General Mining Law and related legislation, surface rights are independent of mineral rights.

 

The law requires that the holder of a mineral concession either reach an agreement with the landowner before starting relevant mining activities (i.e., exploration, exploitation, etc.) or complete the administrative easement procedure, in accordance with the applicable regulation.

 

Surface property is acquired through

 

(i) The transfer of ownership by agreement of the parties (derivative title), or

(ii) Acquisitive prescription of domain (original title).
 
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Temporary rights to use and/or enjoy derived powers from a surface property right may be obtained through usufruct (a right to temporarily use and derive revenue) and easements.

 

As indicated by Nexa, the Mine is located within the following surface rights as shown in Figure 3-3:

 
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Figure 3-3: Surface Rights

 
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i. Property of 500 ha.

 

On November 24, 2005, Nexa Peru acquired this surface property right from Comunidad Campesina de Chavín (Public Registry Record Partida 11026701).

 

ii. Usufruct right of 150 ha.

 

On November 24, 2005 Nexa Peru obtained this usufruct right from Comunidad Campesina de Chavín, in order to install the access road, water transportation pipeline, and power transmission line for the Mine (Public Registry Record Partida 11025833). According to the Public Registry, the agreement states that the usufruct right shall be in force until the mineral reserves of the Mine are exhausted, however, based on article 1001 of the Civil Code this term would be limited to 30 years (i.e., until 2035).

 

iii. Old Power Transmission Line

 

On March 1, 2013, through Ministerial Resolution 082-2013-MEM/DM, Nexa Peru obtained the permanent easement for the New Power Transmission Line of 60 kV S.E. Desert – SE Cerro Lindo (modification) located in the district of Chavin, Grocio Padro and Pueblo Nuevo, province of Chincha, department of Ica.

 

On August 13, 2014, through Ministerial Resolution 363-2014-MEM/DM, Nexa Peru obtained the permanent easement for the of 60 kV S.E. Desert - Tower 39 and its derivations located in the district of Chavin, Grocio Prado and Pueblo Nuevo, province of Chincha, department of Ica.

 

iv. Seawater Desalinization Plant

 

The seawater desalinization plant has been built in an area of 12.9676 ha in the district of Grocio Padro, province of Chincha, department of Ica.

 

Cerro Lindo carried out an investigation which concluded that the property occupied by the desalinization plant is State property. On May 4, 2017, Nexa Peru applied for an occupation easement before the Superintendency of State Property (SBN) under Law 30327 and Supreme Decree 2-2016-VIVIENDA. A temporary easement was issued in the interim until final approval is made.

 

v. Seawater Intake Plant

 

Since April 2007, Nexa Peru has owned aquatic and surface rights to a zone of capture of seawater in Jahuay Beach (1,495 ha).

 

Nexa Peru has obtained aquatic rights through an authorization to use the aquatic area, which was granted by the Peruvian Navy by Directorate Resolution 466-2008-MGP-DCG, and then modified by Directorate Resolution 706-2012-MGP/DCG issued on July 23, 2012. The latter resolution extended the approved aquatic area up to 1,390.10 m2, which allowed Nexa Peru to install four pipelines to extract water from the ocean, and one to discharge effluents. Nexa Peru has paid in full for the use of the aquatic area in years 2016 through 2019, with the 2020 payment pending due to lack of notification, regarding the amount of payment, by the authority because of the COVID-19 pandemic.

 

Nexa Peru is in the process of acquiring surface rights for the remainder of the area through the application for an easement to the SBN under Law 30327 and Supreme Decree 2-2016-VIVIENDA, which is currently ongoing. Application approval is expected to be received by Q3 2021.

 
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vi. Water Pipeline

 

Since April 2007, Nexa Peru has been in possession of all the land occupied by the water pipeline, from the desalinization plant to the mine. Nexa Peru carried out an investigation which concluded that the water pipeline occupies three lots, located between the desalination plant and the mine, which are State property. Nexa Peru is in the process of acquiring surface rights through the application for an easement to the SBN under Law 30327 and Supreme Decree 2-2016-VIVIENDA, which is currently ongoing. Application approval is expected to be received by Q3 2021.

 

3.4 Tax Stability Agreement and Mining Special Tax

 

On March 26, 2002, Nexa Peru entered into an Agreement of Guarantees and Measures for Investment Protection with Ministry of Energy and Mines, which will be in force until December 31, 2021. Under this agreement Nexa Peru will benefit tax stability, free commercialization of the products from Cerro Lindo, free disposition of the currencies generated from the export of the products, etc.

 

On October 14, 2011, Nexa Peru entered into an Agreement for the Application of the Mining Special Tax with the Peruvian Government, under which Nexa Peru agreed to pay a statutory tax rate on trimestral operative profits, as approved by Law 29790. This agreement will be in force for the same period as the Tax Stability Agreement, i.e., December 31, 2021.

 

3.5 Material Government Consents

 

This section details the material Governmental Consents required to carry the operation in compliance with applicable Peruvian laws and regulations (Table 3-4). These material Governmental Consents correspond to those permits, licences, authorizations, etc., issued by the applicable governmental authorities, which entitle Nexa Peru to build the components and/or perform the activities that are critical and typical for a mining operation. These components/activities may include: (i) mining activities and related facilities; (ii) beneficiation plant and related activities; (iii) water supply; (iv) effluent discharge and related facilities; (v) use of explosives; and (vi) power supply. Of note, the Third Amendment to the Mine Closure Plan is under review and approval process by the Peruvian Authorities.

 

Table 3-4:             Main Government Consents

Nexa Resources S.A. – Cerro Lindo Mine

 

#

Government Consent

Resolution

Approval Date

Environmental Certification
1 Cerro Lindo Environmental Impact Assessment RD 325-2004-MEM-AAM 02/07/2004
2 Environmental Impact Assessment for the Jahuay - Cerro Lindo access road RD 37-2006-MTC/16 30/05/2006
3 Environmental Impact Assessment for water and energy supply, and for the desalination plant. RD 134-2007-MEM-AAM 02/04/2007
4 First Amendment to Cerro Lindo Environmental Impact Assessment (Components Relocation) RD 204-2007-MEM-AAM 08/06/2007
5 Second Amendment to Cerro Lindo Environmental Impact Assessment (Expansion of Beneficiation Plant Capacity) RD 168-2010-MEM-AAM 17/05/2010
 
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#

Government Consent

Resolution

Approval Date

6 Amendment to the EIA for the production expansion to 10,000 MT/day, and for water and energy supply and desalination plant. RD 239-2011- MEM/AAM 08/08/2011
7 First Supporting Technical Report for modification of components of the concentrator plant according to report 154-2014-MEM-DGAAM/DNAM/DGAM/D (Expansion of processing capacity to 10,000 MT/day) RD 069-2014-MEM/DGAAM 30/01/2014
8 Second Supporting Technical Report to RD 239-2011-MEM-AAM (Expansion of processing capacity to 17,988 MT/day) RD 391-2014-MEM-AAM 31/07/2014
9 Third Supporting Technical Report to RD 239-2011-MEM-AAM (Expansion of Pahuaypite 1 storage capacity (10%) and Contingency Pond) RD 48-2016-SENACE/DCA 14/07/2016
10 Detailed Technical Report RD 258-2016-MEM-DGAAM 31/08/2016
11 Modification to the Environmental Impact Assessment (MEIA) of Cerro Lindo RD 039-2018-SENACE-JEF/DEAR 13/03/2018
12 Supporting Technical Report to the MEIA DR 039-2018-SENACE RD 001-2019-SENACE-PE/DEAR 3/01/2019
13 Supporting Technical Report to the MEIA DR 039-2018-SENACE RD 134-2019-SENACE-PE/DEAR 22/08/2019
14 Supporting Technical Report to the MEIA DR 039-2018-SENACE RD 00145-2020-SENACE-PE/DEAR 02/12/2020
Mine Closure Plan
1 Cerro Lindo Mine Closure Plan RD 326-2009-MEM-AAM 20/10/2009
2 First Mine Closure Plan Update RD 84-2013-MEM-AAM 22/03/2013
3 First Amendment to the Mine Closure Plan RD 432-2012-MEM-AAM 19/12/2012
4 Second Amendment to the Mine Closure Plan RD 287-2016-MEM-DGAAM 29/09/2016
Mine and Waste Rock Facilities
1 Authorization to start the underground mining activities and the approval of the Mining Plan RD 139-2007-MEM/DGM 17/08/2007
2 Authorization to construct and operate Pahuaypite waste dump RD 0587-2018-MEM-DGM/V 04/07/2018
Beneficiation Plant and Tailing Storage Facilities
1 Beneficiation Concession Title for operation of Concentrator Plant with 5,000 MT/day capacity RD 119-2007-MEM/DGM 13/07/2007
2 Authorization to operate the beneficiation plant at 7,490 Mt/day RD 10-2010-MEM-DGM/V 14/01/2010
3 Authorization to operate additional components for the beneficiation plant RD 77-2011-MEM-DGM/V 01/03/2011
 
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#

Government Consent

Resolution

Approval Date

4 Authorization to operate additional components for the beneficiation plant RD 182-2011-MEM-DGM/V 07/06/2011
5 Amendment to the Beneficiation Concession for construction of the contingency deposit for temporal storage of filtered tailings RD 138-2012-MEM-DGM/V 03/05/2012
6 Authorization to operate the Pahuaypite 2 filtered tailings deposit, and the contingency pond RD 323-2012-MEM-DGM/V 10/10/2012
7 Authorization to operate additional components for beneficiation plant capacity of 14,990 Mt/day RD 337-2012-MEM-DGM/V 18/10/2012
8 Amendment to the Beneficiation Concession for area expansion and manifold water supply system RD 002-2013-MEM/DGM 10/01/2013
9 Authorization to operate additional components for the beneficiation plant RD 117-2014-MEM-DGM/V. 01/04/2014
10 Authorization to operate additional components for the beneficiation plant RD 412-2014-MEM-DGM/V 04/09/2014
11 Authorization to operate additional components for beneficiation plant capacity of 17,988 MT/day RD 567-2014-MEM-DGM/V 12/12/2014
12 Authorization to operate additional components for the beneficiation plant RD 541-2015-MEM-DGM/V 05/11/2015
13 Authorization to operate additional components for the beneficiation plant RD 72-2016-MEM-DGM/V 08/03/2016
14 Approval of a Technical Mining Report for the project “Extension of Pahuaypite 1 tailings deposit and auxiliary components” RD 543-2016-MEM-DGM/V 06/09/2016
15 Authorization to operate the beneficiation plant at 20,000 MT/day and nine additional components RD 0615-2017-MEM-DGM/V 05/07/2017
16 Amendment to the authorization for construction of stage 1 of Pahuaypite 1 tailings deposit RD 260-2018-MEM-DGM/V 21/03/2018
17 Amendment to the Beneficiation Concession to construct a fourth line of filtered tailings and auxiliary infrastructure RD 518-2019-MINEM-DGM/V 23/10/2019
18 Approval of a Technical Mining Report for A 10% increase of the Pahuaypite 2 filtered tailings deposit RD 571-2019-MINEM-DGM/V 19/11/2019
Water Abstraction and Transportation Facilities
1 Sea Water licence RA 33-2012-ANA-ALA 02/03/2012
2 Groundwater licence for IRHS 182 well RA 57-2009-ANA-ALACH-P 08/04/2009
3 Groundwater licence for IRHS 183 well RA 58-2009-ANA-ALACH-P 08/04/2009
4 Groundwater licence for IRHS 179 well RA 26-2011-ANA-ALA S.J. 29/04/2011
5 Groundwater licence for IRHS 180 well RA 27-2011-ANA-ALA S.J. 29/04/2011
 
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#

Government Consent

Resolution

Approval Date

6 Groundwater licence for IRHS 181 well RA 28-2011-ANA-ALA S.J. 29/04/2011
7 Authorization to use aquatic area RD 466-2008/DCG 09/07/2008
8 Modification to the Authorization to use aquatic area for installation of water intake pipelines RD 706-2012- MGP/DCG 23/07/2012
Effluent Discharge to the Environment
1 Effluent Discharge Authorization for Desalination Plant RD 008-2019-ANA-DGCRH 16/02/2019
Power Transmission Lines
1 Power Transmission Concession RS 004-2008-EM 07/02/2008
2 Modification to the Power Transmission Concession RS 006-2012-EM 21/01/2012
3 Permanent easement for the New Power Transmission Line of 60 kV S.E. Desert – SE Cerro Lindo RS 082-2013-MEM/DM 01/03/2013
4 Permanent easement for the of 60 kV S.E. Desert - Tower 39 and its derivations RS 363-2014-MEM/DM 13/08/2014
Use of Explosives
1 Authorization for acquisition and use of Explosives RD 400-2020-SUCAMEC/GEPP 19/02/2020
2 Authorization to operate an underground explosive magazine located on the Chincha – Cerro Lindo highway RD 2976-2019-SUCAMEC/GEPP 13/11/2019
3 Authorization to operate an underground explosive magazine located on the Chincha – Cerro Lindo highway RD 2977-2019-SUCAMEC/GEPP 13/11/2019
4 Authorization to operate an underground explosive magazine located on the Chincha – Cerro Lindo highway RD 2980-2019-SUCAMEC/GEPP 13/11/2019
5 Authorization to operate an underground explosive magazine located on the Chincha – Cerro Lindo highway (currently in process of renewal) RD 126-2015-SUCAMEC-GEPP 20/01/2015
6 Authorization to store explosives and related materials RD 1396-2020-SUCAMEC/GEPP 30/9/2020
7 Authorization to store explosives and related materials RD 1397-2020-SUCAMEC/GEPP 30/9/2020
8 Authorization to store explosives and related materials RD 1398-2020-SUCAMEC/GEPP 30/9/2020

 

Source: Nexa, 2020a. Environmental Certification No. 14 and Authorizations for Use of Explosives Nos. 6 to 8 were granted to Nexa after the release of Nexa, 2020a.

 
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SLR is not aware of any environmental liabilities on the property. Nexa has all required permits to work on the property. SLR is not aware of any significant factors and risks that may affect access, title, or the right or ability to explore and operate on the property.

 
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4.0 Accessibility, Climate, Local Resources, Infrastructure and Physiography

 

4.1 Accessibility

 

The current access from Lima is via the Panamericana Sur highway to Chincha (180 km) and then via an unpaved dirt road (60 km) from Huamanpuquio up the river valley. This dirt road forks at 51 km before reaching the mine site, in order to provide access to the district of Chavín (82 km).

 

The closest commercial airport is Jorge Chavez, at Callao, approximately 300 km northwest. The closest airport to the Project is in Pisco, Ica, however, the Pisco airport is restricted to military and emergency usage.

 

4.2 Climate

 

The Mine is situated in an arid, cold-temperate climate. Rainfall in the region of the operation is minimal, varying on an average monthly basis from 24 mm to 36 mm in the dry season and 108 mm to 150 mm in the wet season. The evaporation rate is approximately 1,500 mm per annum. Rains, when they occur, are typically concentrated in the months of December to March, and for the rest of the year precipitation is generally rare and sporadic. The Mine operates year-round.

 

4.3 Local Resources

 

Various services, including temporary and permanent accommodations, are available in Chavín and the Topará River valley communities (population 2,003, census 2017) located approximately nine kilometres east of the Mine. The communities provide some of the Mine workers, with 122 people working directly for Nexa, and an additional 110 persons being employed by contractors to the operations.

 

A greater range of general services are available at the capital city of Lima, located approximately 270 km to the northwest. All goods and services for the operations are brought in by road from major regional centres or Lima.

 

4.4 Infrastructure

 

The Cerro Lindo operation is comprised of the following main facilities:

 

Approximately 21,000 tonnes per day (tpd) underground mine

Access roads

Powerlines, water pipelines

Desalination plant

Offices and warehouses

Accommodations

Process plant/concentrator

Conveyor systems

Waste rock facilities

Temporary ore stockpiles

 
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Paste backfill plant

Dry-stack tailings storage facilities (TSFs)

 

Additional information on infrastructure is provided in Sections 18 and 20.

 

4.5 Physiography

 

Characterized by rugged topography and steep slopes, the Mine area is located in the occidental Andes mountains at an average elevation of 2,000 MASL. The Mine area is dissected by ravines (quebradas) developed as part of the dendritic drainage pattern feeding the Topará River.

 

Vegetation is limited on hill slopes and is predominantly cacti species. Along river valleys patches of coastal forest may occur. However, these valleys are favoured areas for agricultural activities, so little of the original vegetation remains. During baseline studies conducted in support of environmental permitting, a total of 58 flora species were identified. Following five semi-annual monitoring surveys, the species identified have increased to 85 plant species belonging to 27 families. Two flora species recorded are protected by national legislation.

 
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5.0 History

 

5.1 Exploration and Development History

 

Artisanal-style mining of outcropping barite bodies for use by the oil industry began in the early 1960s. The Cerro Lindo deposit was discovered in 1967, during a colour anomaly reconnaissance program. Colour anomalies result from weathering of pyrite-rich rocks which causes the formation of various reddish iron oxide minerals. Various geochemical sampling and geological studies were subsequently completed. Compañía Minera – Milpo S.A.A. (Milpo), a predecessor company to Nexa Peru, acquired the property in 1984.

 

After acquisition, Milpo prepared access roads and conducted geological mapping, trenching, approximately 3,000 m of underground development, and 3,500 m of drilling. Phelps Dodge optioned the property in 1996, and completed 6,700 m of widely spaced, mostly vertical core drilling, as well as an electromagnetic (EM) moving-loop geophysical survey, which detected a prominent anomaly over the Cerro Lindo deposit. Phelps Dodge also carried out geochemical sampling in 1996 and 1997, which returned an intense zinc anomaly (Gariépy and Hinostroza, 2004 and Milpo, 2016e). Phelps Dodge returned the property to Milpo in 1997.

 

Milpo resumed exploration in 1999, conducted a thorough review of previous work, and decided to proceed with an extensive exploration program, consisting of core drilling and underground drift development. This program was completed in three distinct phases from 1999 through 2001.

 

During the three phases, Milpo completed a total of 28,371 m (129 holes) of core drilling and 1,365 m of underground drifting. Drift development provided access for delineation drilling and exploration of the southeastern portion of OB-1. During this program, Milpo studied the OB-1 and OB-2 zones, confirmed the presence of OB5, and achieved the drill grid density required for a feasibility study.

 

AMEC Simons/GRD Minproc (2002) and GEMIN (2005) completed feasibility studies. Mine construction started in 2006. At the beginning of operations, the plant had a 5,000 tpd treatment capacity; since then, three expansions have been carried out. The plant capacity was increased to 10,000 tpd in 2011, 15,000 tpd in 2012, and 18,000 tpd in 2014 (Milpo, 2016f). Current capacity is at nameplate 20,800 tpd, with actual production scheduled at 20,600 tpd over the life of mine (LOM) plan. Nexa has been granted approval for the terms of reference for an updated Environmental Impact Assessment (EIA), in which an expansion to 22,500 tpd is contemplated (see Section 17).

 

Systematic exploration restarted in 2007. This exploration resulted in discovery of new mineralized bodies (OB-6 in 2006; OB-7 in 2009; OB-6A in 2010; OB-6B in 2011; OB2B and OB-8 in 2012; OB-5B in 2013; OB3–4 in 2014; OB-8 in 2015; OB-11 in 2016, OB-9, OB-10 in 2017, OB-12 in 2018, OB-13, OB-14 in 2019 and expanding volume of OB-5B and OB-13 in 2020), as well as increasing, and upgrading the classification of, estimated Mineral Resources and Mineral Reserves in previously known mineralized bodies.

 

5.2 Past Production

 

A summary of production to date is included in Table 5-1. 

 
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Table 5-1:              Production History

Nexa Resources S.A. – Cerro Lindo Mine

 

    Unit   2007   2008   2009   2010   2011   2012   2013   2014   2015   2016   2017   2018   2019   2020
Tonnage   Mt   0.64   1.97   2.41   2.53   3.14   3.79   5.38   5.93   6.76   7.35   7.30   6.91   6.80   5.48
Zn Grade   %   3.19   4.12   3.51   3.14   3.15   3.08   3.12   3.06   2.83   2.56   2.33   2.07   2.05   1.93
Cu Grade   %   0.4   0.59   0.76   0.79   0.81   0.86   0.77   0.79   0.68   0.66   0.69   0.64   0.64   0.59
Pb Grade   %   0.49   0.58   0.43   0.34   0.34   0.29   0.32   0.33   0.30   0.29   0.27   0.25   0.25   0.29
Ag Grade   g/t   34.2   33.6   28.3   29.9   26.1   23.0   23.3   23.3   23.3   22.7   21.6   21.6   21.6   24.14

 

Production in 2020 was significantly lower than in 2019 due to the effects of the COVID-19 pandemic and associated production interruptions. On March 15, 2020, the Peruvian Government declared a national emergency and imposed operating business restrictions including on the mining sector. The quarantine period was initially expected to last until the end of March but was subsequently extended up to May 10, 2020. In light of the government restrictions, Nexa suspended production at Cerro Lindo. During this period, mining activities were limited to critical operations with a minimum workforce to ensure appropriate maintenance, safety, and security. On May 6, the Peruvian Government announced the conditions for the resumption of operations for different sectors, including mining operations above 5,000 tpd. Cerro Lindo operations, which were suspended on March 18, restarted production on May 11, 2020, following the end of the quarantine period. After the resumption of operations, Cerro Lindo ramped up production to pre-pandemic levels by June 2020.  

 
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6.0 Geological Setting, Mineralization, and Deposit

 

6.1 Regional Geology

 

The Cerro Lindo deposit is located in a 30 km by 10 km northwest trending belt of marine volcano-sedimentary rocks of the Middle Albian to Senonian (mid-Cretaceous) Huaranguillo Formation, belonging to the Casma Group (Zalazar and Landa, 1993), which in turn is surrounded by Tertiary intrusions of the Coastal Batholith (Figure 6-1). The Casma Group is dominated by porphyritic andesites, erupted in a failed back-arc basin through an unexposed older basement as a result of extensional tectonics during subduction of oceanic lithosphere. The Casma volcano-sedimentary rocks extend for 1,600 km along the Pacific Ocean, from Ica, Southern Peru, to Piura, Northern Peru.

 

Upper Cretaceous to Tertiary intrusive rocks of the Coastal Batholith intrude the Casma Group over most of its extent. In the Cerro Lindo region, this intrusive belt is composed of granodiorites, monzogranites, and diorites of calc-alkaline affinity. Emplacement of the batholith occurred episodically over a period of 64 million years between 101 Ma and 37 Ma. The Coastal Batholith is composed of the Catahuasi, Incahuasi, and Tiabaya superunits, which overlie volcanic rocks and are generally of granodioritic to tonalitic composition, with varying granulometry. Andesitic porphyry dikes cross-cut all units in a general north-south orientation. Emplacement of the batholith generated intense contact metamorphism of the adjacent volcano-sedimentary rocks. In the Cerro Lindo area, a medium grade regional andalusite-cordierite metamorphism developed.

 

The Huaranguillo Formation fills the Canete volcano-sedimentary basin, one of the several similar basins that form the Casma Metallotect at the western side of the Andean Cordillera Occidental. The Huaranguillo Formation is approximately 3,000 m thick; it has intercalated volcanic rocks at its base, intermediate volcanic with some shale intercalations in its upper part, and black calcareous rock in millimetre to centimetre thick layers at the top of the sequence. The Casma Metallotect hosts a number of important volcanogenic massive sulphide (VMS) deposits, including Tambogrande, Perubar, Cerro Lindo, Potrobayo, Totoral, Maria Teresa, Aurora Augusta, and Palma. 

 
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Figure 6-1: Regional Geology

 

 
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6.2 Local and Property Geology

 

Geological mapping at 1:10,000 scale was completed by Hinostroza (2016). Figure 6-2 shows the resulting map. The Huaranguillo Formation, at the property scale, consists of an approximately 2,250 m thick back-arc basin sequence extending northwest-southeast for approximately 10 km x 5 km. Zalazar and Landa (1993) divided the Huaranguillo Formation in the Cerro Lindo area into two members: a lower member, composed of shales, tuffs and andesites, and an upper member, formed of limestones, shales and volcanic rocks. Hinostroza (2016) later divided the Huaranguillo Formation into three units as described below.

 

The local stratigraphy of the Cerro Lindo deposit is shown in Figure 6-3 and described as follows:

 

1. Huaranguillo Formation (105 to 106 Ma): This formation is part of the Casma Group, of the lower Cretaceous Albian, and at Cerro Lindo is made up of three members (Hinostroza, 2016):

 

(a) Lower Member: made up of four lithological units: rhyolites, dacites, volcanic gap, and volcanoclastic, named by Canales (2016)

 

(i) Rhyolite: generally occurs as long bodies with northwest-southeast directions, and is structurally controlled. These rocks are white in colour with a pinkish hue, have aphanitic and/or rarely porphyritic texture, have quartz eyes and in some cases spherulites surrounded by quartz (filled vesicles type), and are mostly silicified, with sulphide dissemination.

 

(ii) Dacite: observed encompassing or interspersed with the rhyolites. These rocks are white to brown grey in colour, aphanitic to porphyritic, isotropic to anisotropic, not magnetic. Their texture is variable, the most prominent being the mosaic-like (or toad spine), porphyroblastic texture, due to the presence of cordierites in its composition (product of metamorphism); porphyritic textures are also observed, represented by some phenocrystals of plagioclase wrapped in a matrix. In areas without deformation, the dacite is isotropic, while in areas related to deformations and metamorphism it is anisotropic, showing northwest-southeast foliations and a certain relationship with mineralized bodies.

 

(iii) Volcanic gap: discontinuous rock, a product of the volcanism in rhyolites and dacites, consisting of angular to sub-angular fragments of the massive rhyolite, of centimetre size (<20 cm) and with well-defined edges, wrapped in a fine matrix of dacitic composition. These gaps show gradation in the percentage of rhyolitic fragments, from 1% to approximately 25%.

 

(iv) Volcanoclastic: located in the upper parts of the lower limb (e.g., Cerro Paltarumi). It is made up of elongated sub-rounded monomictic fragments of rhyolite (up to 60 cm in its major axis) of undefined edges in an aphasic matrix of andesitic composition.

 
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Figure 6-2: Geological Map of the Cerro Lindo Property

 

 
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Figure 6-3: Local Stratigraphic Column

 

 
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(b) Upper Limb Member: consists mainly of an intercalation of shales with massive and vesicular andesites that in some cases have porphyritic texture. It is best exposed along the UMCL road towards Chavín and on Cerro Paltarumi, at an altitude greater than 2,400 MASL, showing an anomaly of reddish colour in satellite images.

 

(i) At the base of the member, layers of shales-siltstones with thicknesses of up to two metres, called “guiding shales”, are indicative of the contact between acidic and intermediate sequences.

 

(ii) Shales: black shales with thicknesses of up to 10 cm that are interspersed with millimetre thick limolite laminae, forming strata of up to two metres. These strata are rich in iron, which gives reddish colour to the areas of weathering.

 

(iii) Massive andesites: usually grey to greenish grey, with an aphanitic texture, not magnetic. Occasionally they have plagioclase or hornblende crystals smaller than two millimetres.

 

(iv) Vesicular andesites: very similar to the massive, but with the presence of vesicles of up to 15 cm, however, averaging less than three millimetres in size, and filled mainly by calcite and occasionally biotite, and rarely by quartz or amphibole. Occasional plagioclase phenocrystals are observed near or in contact with intrusive bodies.

 

(c) Roof Member: characterized by calcareous sedimentary phases, layers of marl-shales interspersed with massive andesites in the lower part, and limestone strata with narrow layers of limolites and hornfels in the upper part.

 

(i) Marls-shales: observed as “Roof pendant” in the uppermost zones of the intrusive (mainly in the Catahuasi Superunit). These appear to be strongly silicified, in some cases classified as hornfels with random stratification.

 

(ii) Limestone-hornfels: thicker than one metre, observed at elevations over 2,500 MASL (to the southwest of the town of Chavín), characterized by intercalations of dark, centimetre thick and white, millimetre thick laminae. These laminae are separated by millimetre thick limolite layers and form greater than 400 m thick strata, intensively folded in a northwest-southeast direction and in some sectors cut by rhyolitic dikes.

 

2. Intrusives: Three main intrusives are identified in the Huaranguillo Formation with ages of Turonian to Campanian: Catahuasi, Incahuasi, and Tiabaya superunits.

 

(a) Catahuasi Superunit: located on the Campanario Hill, generally striking northwest-southeast, and has an extension striking northwest-southeast over a distance of no greater than three kilometres, structurally controlled (Ahem Patahuasi Fault). This superunit consists mainly of a white to light grey, isotropic, equigranular fine grained, non-magnetic granodiorite-tonalite with 15% of hornblende (main mafic mineral). Its age by the U-Pb method is on average 93.72 Ma (Meffre and Thompson, 2016).

 

(b) Incahuasi Superunit: located west of the Paltarumi Hill, west of the Pucasalla Creek. It is composed of grey-pink, grey-dark coloured, isotropic to anisotropic, equigranular medium grained granodiorite-granite. The lower limb of the superunit is in contact with the volcanic sequences, where strong deformation and partial fusion produced metavolcanic rocks. Its age by the U-Pb method is on average 82.35 Ma (Meffre and Thompson, 2016).

 
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(c) Tiabaya Superunit: located north of the Mesarumi Hill and is characterized by the presence of enclaves of microdiorites and massive andesites. This unit is composed of grey coloured, isotropic, equigranular coarse grained tonalite with hornblende being the main mafic mineral. According to INGEMMET, it has differentiated into five magmatic pulses, forming a structure centred along the San Juan River valley, where it has an average age of 80 ± 8 Ma (Pitcher et al., 1985).

 

3. Other dikes: There are three different types of dikes, of which the andesitic porphyry is the most abundant.

 

(a) Andesitic porphyry: most predominant among the dikes, is greenish grey in colour, has porphyritic texture, and is isotropic with moderate magnetism. Its porphyritic texture is marked by the presence of euhedral phenocrystals of plagioclase and burners of sizes up to five millimetres encompassed in a green fine grained matrix. Its age by the U-Pb method is on average 73.89 Ma (Meffre and Thompson, 2016).

 

(b) Rhyodacitic porphyry: cuts the andesitic porphyry dikes, is greenish grey in colour, has porphyritic texture, and is isotropic, non-magnetic. Its texture is marked by the presence of euhedral feldspar phenocrysts of less than three millimetres, anhedral quartz eyes of up to five millimetres, and subhedral hornblende of up to one millimetre; encompassed in a green fine grained matrix.

 

(c) Dacitic porphyry: observed on the Quishpi Pata Hill, has a north-northeast to south-southwest orientation and a thickness of up to 5 m. Cuts the upper member of the Huaranguillo Formation, and is cut by the Catahuasi Superunit. It is white in colour, has an aphanitic texture, and demonstrates occasional euhedral quartz phenocrystals in an aphanitic matrix.

 

6.2.1 Structural Geology

 

The regional faults in the Cerro Lindo Mine area trend northwest-southeast, north-south, and northeast-southwest, parallel to the Topará Creek. The north-southeast faults are the main controls on volcanic sequences and mineralized bodies.

 

A number of fault systems are recognized:

 

A system of syn-volcanic faults, related to the formation of the deposit, has a northwest to southeast strike.

A conjugate fault system, striking northeast-southwest, that controls the Topará Fault; the Topará Fault displays right lateral movement.

Late north-south fault system that controls the emplacement of barren dikes that cut the main mineralized zones.

Reverse fault along the contact between rhyolite and the rocks of the Coastal Batholith.

 

These fault systems have defined structural blocks, and the paleosurface on which the deposit was probably formed (Figure 6-4).

 

Huaranguillo Formation rocks have been moderately to intensely folded and faulted in the Mine area. The structural pattern corresponds to open folds accompanied by a weak to very weak schistosity, however, certain shear zones locally produce intense schistosity. 

 
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Figure 6-4: Vertical Section through Mineralized Bodies Showing Mineralization Types

 

 
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6.2.2 Metamorphism

 

Intense contact metamorphism of the volcano-sedimentary sequences near the contacts with the Coastal Batholith intrusions reaches the garnet-cordierite-andalusite facies. Most andalusite formed at the footwall, probably as a result of strong sericitization (increased potassium).

 

Typically, secondary porphyroblastic textures developed in volcanic rocks as a result of contact metamorphism. Granoblastic textures are also common. However, drilling indicates that the intensity of metamorphism is irregular. Nearly 10% of the volcanic rocks still retain the primary flow breccias and banding textures.

 

Massive sulphides at Cerro Lindo have been recrystallized to grain sizes ranging from two to five millimetres, however, approximately 10% of the sulphides, mainly pyrite-chalcopyrite, show a very weak metamorphism where the grain size rarely exceeds 0.5 mm.

 

6.3 Deposit Geology

 

6.3.1 Extrusive Rocks

 

Rhyolitic to rhyodacitic rocks predominate in the deposit area. Flow, brecciated, and laminated textures exhibiting amygdules are frequent, as are andesitic pillow lavas. Intense thermal metamorphism produced porphyroblastic and granoblastic structures. The main rock-forming minerals are quartz, feldspar, biotite, sericite, andalusite, and pyrite.

 

Exhalite layers, typical of VMS deposits, are locally observed at the bottom or top of massive sulphide bodies, where they form finely laminated, thin (less than one metre) horizons composed of silica (chert) and various sulphides. These layers are limited to the immediate area of the sulphide deposits.

 

6.3.2 Intrusive Rocks

 

Coastal Batholith intrusive rocks, with ages ranging from Upper Cretaceous to Tertiary, were intruded between 101 Ma and 37 Ma. The batholith is primarily composed of granodiorites surrounding roof pendants of the volcano-sedimentary units. Some minor microdiorite, diorite, and gabbro bodies, as well as numerous dikes, cut the volcano-sedimentary sequences. The most common are microdiorite, medium grained diorite, granodiorite, and andesitic porphyry (the latter also cuts the granodioritic intrusion).

 

Late-stage feldspar porphyritic dikes occur throughout the property, cutting both the Casma Group and Coastal Batholith rocks. At Cerro Lindo, these form a northeast-southwest trending swarm.

 

6.3.3 Alteration

 

Along with the formation of massive sulphide bodies, different types of hydrothermal alteration halos developed: silicification at the root, chloritization along the edges of the base, and sericitic alteration, which forms the widest halo (from proximal K-sericite to more distal Mg-sericite). Figure 6-5 shows a cross-section schematic of the massive sulphide at Cerro Lindo with its hydrothermal alteration halos, possible isotherms of hydrothermal fluid at the time of mineralization, and the distribution of chemical elements in the different areas of the deposit.

 

The metamorphic activity associated with the coastal batholith has overprinted the hydrothermal alteration. Most notable is the development of porphyroblasts of cordierite in the previously altered volcanic rocks. 

 
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Figure 6-5: Cross-Section Schematic of the Massive Sulphide at Cerro Lindo

 

 
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6.4 Mineralization

 

Mineralization is hosted by a pyroclastic unit composed of ash and lapilli-type polymictic tuffs with subrounded, well classified fragments. Some lapilli have centimetre-scale, pencil-like shapes, due to development of an incipient schistosity.

 

Eight styles of mineralization were identified at the Cerro Lindo deposit:

 

1. Pyritic, homogeneous, primary massive sulphide (SPP): This unit includes almost exclusively pyrite, less than 10% barite, and minor interstitial chalcopyrite. Its structure is equigranular, generally coarse grained (3 mm to 6 mm), but with fine-grained areas (0.4 mm to 2 mm)

2. Copper-rich, baritic homogeneous primary sulphides (Cu-SPB): This unit contains more than 50% total sulphides (including barite), and more than 10% barite. Barite is associated with sulphides because it was deposited from the same solution at the same time as the sulphides. Its structure is homogeneous, and it is composed of barite, pyrite, pyrrhotite, chalcopyrite, and brown sphalerite. Sulphides typically occur as intergrowths and patches, and brown sphalerite is included in chalcopyrite grains. There is less pyrite than in the Zn-SPB unit (described below). The Cu-SPB is generally found within or near the contact with Zn-SPB and SPP.

3. Zinc-rich, banded, baritic primary sulphides (Zn-SPB): This unit comprises more than 50% of total sulphides (including barite), and more than 10% barite. The Zn-SPB unit contains variable proportions of pyrite, barite, yellow sphalerite, and galena. It is typically banded and has a coarse grain size (3 mm to 6 mm).

4. Semi-massive sulphides (SSM): This unit contains between 20% and 50% sulphides, which are mostly represented by barren pyrite as disseminations, patches, stringers, and stockworks. This mineralization is generally fine grained as compared to massive sulphides. SSM forms a variable envelope, 20 m to 80 m thick, around the massive sulphide bodies. The sulphide proportion decreases outward. It is better developed in the footwall.

5. Pyritic oxidized sulphides (SOP): This unit comprises bornite and covellite, and is mostly located in the OB2 mining production area.

6. Baritic oxidized sulphides (SOB): This unit comprises bornite, covellite, and oxidized zinc, and it is also located in the OB2 mining production area.

7. Leached massive sulphides (SLB) and leached semi-massive sulphides (SSL): These units are located near surface in the OB2 mining production area.

8. Mineralized volcanic rocks (VM): This unit contains rhyolite and dacite rocks with some chalcopyrite and sphalerite disseminated in veinlets or patches, located on the edge of the mineralized zones.

 

Cerro Lindo contains 19 mining production areas within the mineralization domains. The mineralized lenses exhibit an irregular elongated geometry. Their longest axis (nearly 500 m) has a northwest-southeast horizontal trend (azimuth 135°). The mineralized bodies are approximately 300 m thick (occurring between 1,600 MASL and 1,980 MASL) and 100 m wide. They are the largest near the edge of the Topará Ravine, beyond which they diminish in size toward the southeast. The mineralized bodies generally dip to the southwest at 65° on average. Locations of the main mineralized bodies within the mining production areas are shown in Figure 6-6. Table 6-1 shows the dimensions of each mineralized body within the mining production areas. 

 
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Table 6-1:        Dimensions of Main Mineralized Bodies within Mining Production Areas

Nexa Resources S.A. – Cerro Lindo Mine

 

Description   Unit   OB-1   OB-2   OB-2B   OB-3–4   OB-5   OB-5B   OB-5C   OB-5D   OB-6   OB-6A   OB-6B   OB-6C   OB-7   OB-8   OB-9   OB-10   OB-11   OB-12   OB-13   OB-14
Length   m   350   450   420   150   350   635   200   40   200   460   200   100   170   350   300   400   250   150   500   270
Width   m   200   220   60   20   65   80   15   35   50   70   60   80   50   100   60   70   120   100   100   20
Average thickness   m   100   200   80   40   45   70   35   15   80   80   65   25   60   45   70   85   3   4   50   12
Depth   m   360   330   260   330   400   245   90   110   450   260   245   70   210   70   190   380   25   70   275   275
Top elevation   m   1,850   1,970   1,950   1,950   2,000   1,805   1,780   1,640   2,000   2,020   1,975   1,995   1,940   1,700   1,950   1,670   1,550   1,960   1,970   1,990
Bottom elevation   m   1,490   1,640   1,690   1,620   1,600   1,560   1,690   1,530   1,550   1,760   1,730   1,925   1,730   1,440   1,760   1,290   1,450   1,840   1,780   1,520

 

 
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Figure 6-6: Main Mineralized Bodies within Mining Production Areas

 

 
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The majority of these bodies show three types of mineralization. The upper part features the massive mineralization of barite, sphalerite, galena, and pyrite (SPB). The lower part includes massive pyrite (SPP), with two different general grain sizes, one fine grained with a higher chalcopyrite content and the other coarse grained and largely barren. In the lateral portions, mineralization is semi-massive, contains 20% to 50% sulphides, and occurs as disseminations, patches, and stockworks. The base of the system exhibits a cluster of small veins of pyrite, pyrrhotite, and to a lesser extent, chalcopyrite. The mineralization at Cerro Lindo is generally coarse grained, which may be related to recrystallization due to the contact metamorphism, and this improves metallurgical recovery.

 

The massive sulphide frequently presents a marked banding, which may be related to tectonic deformation. In the contact with the adjacent batholiths, there is a noticeable predominance of remobilized sulphides elongated in banding that runs parallel to the volcanic contact with the intrusives. The rigidity of the batholiths likely fostered the generation of areas of greater sulphide deformation and mobilization, as illustrated in Figure 6-4.

 

Recently, a new domain termed mineralized volcanic (VM) has been identified, which differs from the other lithologies because it does not contain massive sulphides. The mineralization is scattered or occurs as patches in the volcanic rock and consists of mainly tetrahedrite, freibergite, sphalerite, and galena. Typical metal concentrations in VM are up to 15% Fe; 1% Zn, and greater than 0.25% Cu, 0.50% Pb, and 30 ppm Ag.

 

Significant barite is present mainly in the upper portions of the deposit. A secondary enrichment zone, composed of chalcocite and covellite, formed near surface. Silver-rich powdery barite remains at surface as a relic from sulphide oxidation and leaching.

 

The lead content is usually low and is mainly associated with high grade zinc zones, and locally with late quartz veins or small volcanic enclaves. These enclaves represent approximately 2% to 3% of the deposit volume, and commonly measure 0.5 m to 10 m in diameter. Silver grades correlate well with copper and lead.

 

As is typical of Kuroko-style VMS deposits, Cerro Lindo is characterized by a distinct mineralization zonation. Figure 6-5 shows the chemical zonation patterns in a cross-section schematic. Amec Foster Wheeler Perú S.A. (Amec, 2017) noted that:

 

Zinc content is higher in the Zn-SPB units.

 

Copper content is higher in Cu-SPP units. However, copper is also found in the SPB unit.

 

Lead grades are higher in SPB units and are significantly reduced in SPP units. Some lead is found in SPP associated with SPB or in enclaves. The silver content is significantly higher in SPB, but it is sometimes also important in SPP units. The presence of silver in SPB is due to its affinity for lead.

 

Zinc, lead, and silver grades are always higher in SPB than in SPP; copper grades are always higher in SPP.

 

The copper grades tend to decrease from the northwest to the southeast; whereas zinc, lead, and silver grades tend to increase in the same direction

 

6.5 Deposit Types

 

This section is largely based on Amec (2017).

 

Gariépy and Hinostroza (2014) highlighted the similarities between the Cerro Lindo deposit and the Kuroko deposits in Japan. Kuroko deposits have been described by Ishihara (1974), Franklin et al. (1981), Ohmoto and Skinner (1982), and Urabe et al. (1983). Singer (1986) defined the Kuroko VMS descriptive deposit model as copper- and zinc-bearing massive sulphide deposits in marine volcanic rocks of intermediate to felsic composition. 

 
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These deposits are hosted by Archean to Cenozoic marine rhyolite, dacite, and subordinate basalt and associated sediments, principally organic-rich mudstone or pyritic, siliceous shale. Lava flows, tuffs, pyroclastic rocks, and breccias are common volcanic rock types. Felsic (rhyolitic) domes are sometimes associated. The depositional environment consists of hot springs related to marine volcanism, probably with anoxic marine conditions. Lead-rich deposits are associated with abundant fine grained volcanogenic sedimentary rocks. Black smokers are analogous modern deposits associated with back arc basins.

 

Kuroko deposits comprise an upper stratiform massive (>60% sulphide) zone (black ore) containing pyrite + sphalerite + chalcopyrite ± pyrrhotite ± galena ± barite ± tetrahedrite ± tennantite ± bornite with lower stratiform massive zone (yellow ore) – pyrite + chalcopyrite ± sphalerite ± pyrrhotite ± magnetite and a basal stringer (stockwork) zone–pyrite + chalcopyrite (gold and silver).

 

Following descriptions by AMEC (2002), Gariépy and Hinostroza (2014), Lavado (2015), and Imaña (2015), the general features of the Cerro Lindo deposit are presented in Table 6-2. These features clearly support the classification of Cerro Lindo as a Kuroko-type VMS deposit.

 

Table 6-2:          General Features of the Cerro Lindo Deposit 

Nexa Resources S.A. – Cerro Lindo Mine

 

Type   General Features
Lithologies   Rhyolite, dacite, rhyodacite, minor andesite, microdiorite
     
Rock textures   Massive, lava flows, breccias and tuffs
     
Age   Lower Cretaceous
     
Mineralogy   Pyrite, sphalerite, galena, barite; chalcopyrite mainly in stringer zones
     
Mineralization   Massive and coarse grained to banded and fine grained; stockworks in stringer zones
     
Zoning   Sphalerite-rich to pyrite-chalcopyrite-rich zones
     
Alteration   Sericitization, pyritization, chloritization, silicification
     
Ore control   Lens-shaped bodies: stringer zones.
     
Geochemical signature   Zn, Pb. Ba, Ag, Cu mainly in massive and banded portions; Cu also occurs in stringer zones
     
Depositional environment   Proximity to volcanic centre, volcanic depression with volcano-clastic contribution
     
Tectonic setting   Graben-like structure within back-arc basin; roof pendant

 

The Cerro Lindo deposit is altered by thermal metamorphism caused by the adjacent batholiths and slightly deformed, possibly due to the basin’s inversion tectonics. It is a massive sulphide deposit formed by nineteen known mineralized bodies to date, all hosted in dacite and breccia located along the edges of the rhyolite domes. The mineralized bodies have a clear control along the 135° azimuth and are abruptly bounded by a possible structure running parallel to the Topará Ravine, from northeast to southwest. 

 
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The mineralized bodies diminish in size with distance from the Topará Ravine, which suggests the hypothesis that the possible structure running parallel to the Topará Ravine is a raised structure and feed zone for the hydrothermal system. The massive sulphide bodies have a well-defined internal architecture (barite and sphalerite at the top and pyrite and chalcopyrite at the base). Around these bodies, well-defined hydrothermal alteration halos are preserved, with silicification and Fe-chlorite at the root, K-sericite to the sides, and Mg-sericite along the outermost edge. Figure 6-7 shows a schematic section transversal to sulphide orebodies and intrusions (Marcelo Imaña, pers. comm.,2019).

 

Cerro Lindo is a Kuroko-style VMS deposit with economic grades of Zn, Cu, Pb, and Ag. 

 
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Figure 6-7: Schematic Section Transversal to Sulphide Orebodies and Intrusions

 

 
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7.0 Exploration

 

Nexa has been conducting exploration and development work at Cerro Lindo since 2006. Most of the exploration is generally conducted simultaneously with underground development. This work has included geological mapping, geophysics, diamond core drilling, and channel sampling.

 

7.1 Exploration

 

7.1.1 Geological Mapping

 

Zalazar and Landa (1991) prepared the first geologic map on the region while working for the state-owned Ingenmet. In addition, various geological mapping campaigns and studies were conducted by Phelps Dodge and Milpo during the late 1990s and early 2000s (Amec, 2017).

 

More recently, Lavado (2015), Canales (2016), and Anglo Peruana Terra (APT) (2017, 2018) conducted detailed geological mapping campaigns on the area:

 

Lavado (2015) mapped 1,300 ha in the mine area and its immediate vicinity at 1:4,000 scale. The mine stratigraphy and alteration pattern, as well as factors controlling the mineral deposition, were better outlined.

 

Canales (2016) conducted a 1:10,000 geological mapping program that extended over 13,700 ha. The program included detailed 1:2,000 mapping over 450 ha in the immediate mine area. This program was accompanied by systematic lithogeochemical sampling, and by 8,112 m drilling in 15 drill holes in the Topará North sector. Six holes intercepted mineralized intervals at different elevations.

 

APT (2017) conducted a 1:5,000 geological mapping program that covered over 2,900 ha at Cerro Lindo Sur. This program was accompanied by systematic lithogeochemical sampling. In 2018, a geological mapping program was conducted at a scale of 1:2,000 that covered over 450 ha at Pucatoro.

 

The surface mapping of the Pucasalla, Ventanalloc, and Toldo Chico targets has been continued by Nexa’s Brownfield exploration team.

 

7.1.2 Geochemistry

 

Geochemical samples were collected at different stages during the project life. Information on sampling methods and results is sparse. Samples were collected from soil (by Phelps Dodge; Milpo, 2016d), core (Imaña, 2015), or from rock outcrops (Canales, 2016). Phelps Dodge carried out geochemical studies in 1996 and 1997 and identified a pronounced zinc anomaly.

 

Additional details on geochemical sampling and sampling methods were not available.

 

Imaña (2015) collected 431 rock chip samples from various drill holes located close to OB6 and OB7 as part of a lithogeochemical study oriented at deciphering the chemical and volcanic stratigraphy of the deposit, and chemical modifications that occurred as a result of hydrothermal alteration. Canales (2016) carried out geological mapping and geochemical sampling of rock outcrops in the area of the Mine.

 

In 2019, Nexa’s Brownfield exploration team collected 14 rock chip samples from the Ventanalloc and three rock chip samples from Toldo Chico targets (Nexa, 2020b). The assay results indicate the following:

 

Ventanalloc - Copper results confirmed the surface expression of the mineralized rocks as a possible porphyry system (six out of 13 samples returned 0.3% to 2.38% Cu).

 
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Ventanalloc - Molybdenum is considered one of the most relevant assays for a porphyry hosted Cu-Mo deposit due to its correlation with Cu (two out of 13 samples returned 105 ppm to 120 ppm Mo).

Toldo Chico - One out of three samples returned values of 4,867 ppm Ba, confirming the presence of barite outcrops at Toldo Chico.

 

Table 7-1 and Table 7-2 list the results of the 2019 surface sampling.

 

At Cerro Lindo, surface geochemical sampling has been largely superseded by drilling.

 

Table 7-1:               2019 Rock Chip Sampling Results At Ventanalloc Target

Nexa Resources S.A. – Cerro Lindo Mine

 

Target   East   North   Elevation   Sample
Type
  Sample
 ID
  Zn
(%)
  Pb
(%)
  Cu
(%)
  Ag
(g/t)
  Fe
(%)
  Au
(g/t)
  Ba
(ppm)
  Mo
(ppm)
Ventanalloc   395,145   8,559,815   3,223   Rock Chip   291867   0.00   0.00   0.00   0.50   0.51   0.02   271   2
Ventanalloc   394,748   8,560,015   3,028   Rock Chip   291868   0.01   0.00   0.01   0.40   5.31   0.01   132   1
Ventanalloc   393,479   8,559,574   2,533   Rock Chip   291869   0.00   0.00   0.02   0.30   1.69   0.01   58   45
Ventanalloc   393,355   8,559,567   2,479   Rock Chip   291870   0.04   0.00   1.31   0.80   2.22   0.01   56   11
Ventanalloc   393,318   8,559,556   2,464   Rock Chip   291871   0.01   0.00   2.38   0.50   2.09   0.01   44   20
Ventanalloc   393,231   8,559,640   2,470   Rock Chip   291872   0.01   0.00   1.16   0.40   2.93   0.01   159   29
Ventanalloc   393,048   8,559,487   2,404   Rock Chip   291873   0.01   0.00   0.40   0.60   2.35   0.01   99   19
Ventanalloc   393,000   8,559,462   2,400   Rock Chip   291874   0.00   0.00   0.12   0.90   2.02   0.01   72   120
Ventanalloc   392,895   8,559,207   2,373   Rock Chip   291875   0.00   0.00   0.71   10.70   5.88   0.08   78   42
Ventanalloc   395,238   8,559,529   3,230   Rock Chip   268605   0.17   0.00   0.00   1.00   2.33   0.02   54   1
Ventanalloc   393,645   8,558,431   2,610   Rock Chip   268601   0.01   0.20   0.31   75.20   5.70   0.07   100   33
Ventanalloc   393,166   8,558,608   2,474   Rock Chip   268602   0.01   0.00   0.16   0.80   3.89   0.01   242   105
Ventanalloc   392,861   8,558,475   2,410   Rock Chip   268603   0.01   0.00   0.20   1.70   2.69   0.01   62   23
Ventanalloc   392,673   8,558,581   2,299   Rock Chip   268604   0.02   0.00   0.11   1.80   2.02   0.01   36   81

 

Table 7-2:              2019 Rock Chip Sampling Results At Toldo Chico Target

Nexa Resources S.A. – Cerro Lindo Mine

 

Target   East   North   Elevation   Sample
Type
  Sample
 ID
  Zn
(%)
  Pb
(%)
  Cu
(%)
  Ag
(g/t)
  Fe
(%)
  Au
(g/t)
  Ba
 (ppm)
Toldo Chico   386,656   8,558,262   2,514   Rock Chip   291864   0.01   0.00   0.03   0.10   5.27   0.01   4,867
Toldo Chico   386,425   8,558,030   2,632   Rock Chip   291865   0.03   0.01   0.01   1.20   19.19   0.00   570
Toldo Chico   386,414   8,558,072   2,611   Rock Chip   291866   0.02   0.04   0.01   5.00   1.12   0.01   737

 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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7.1.3 Geophysics

 

In 2012, Quantec performed a Titan 24 direct current induced polarization and magnetotelluric (DCIP & MT) survey over the area of the Cerro Lindo Mine, with approximately 23 line km of data collected. Arce (2014) re-processed and reinterpreted the data.

 

Imaña (2015) presented various resistivity cross-sections resulting from a magnetotelluric survey. The sections did not include legends or scales, and no details were available. Imaña (2015) recommended the use of magnetotelluric and electromagnetic methods, both from surface and underground, in future exploration campaigns, given the massive nature of the Cerro Lindo mineralization.

 

Reinterpretation of the Imaña (2015) data resulted in better definition of OB8, and extensions of other deposits.

 

In 2017, an extensive Titan 24 DCIP & MT survey was carried out by Quantec in an area of 12 km x 6 km at a 500 m line spacing with an objective to reveal new targets under the cover of barren andesitic rocks that overlies the felsic volcanic package. Orcocobre was the main target found, characterized by a combination of anomalous rock chipping, alteration, and low resistivity. This target, however, was discarded as a false positive that was represented by the roots of an eroded VMS system.

 

In December 2019, a borehole electromagnetic (BHEM) study was carried out by GRM-services Oy Ltd over a length of 836.70 m in hole PECLD04626 drilled from the 1600 level with an inclination of -75° and azimuth of N102°. The purpose of the study was to explore below already known mineralized bodies, in particular OB1. The survey indicated good response in the upper portion of the hole and no apparent presence of conductors at depth.

 

A helicopter-borne versatile time domain electromagnetic (VTEM) survey was completed from late 2019 to early 2020 over a number of target areas by Geotech Ltd. (Geotech, 2020). A total of 2,176 line-kilometres of VTEM and caesium magnetometer geophysical data were acquired during the survey.

 

In 2020, Nexa retained Mira Geoscience Ltd. (Mira) to process and interpret the 2017 Titan 24 direct current/induced polarization (DC/IP) and magnetotelluric (MT) survey results and all the geological data (sectional interpretation, surface maps, and drill hole data). The interpretation resulted in a new regional litho-structural model and a 3D geophysical model, highlighting the Cerro Lindo deposit as a conductivity and chargeability anomaly (Mira, 2020). Nexa geologists used the latest model to review the exploration targets, and as a result, an additional seven targets were defined. Interpretations and analysis of the models are continuously updated as new information is incorporated from new holes, and more discussion forums are held.

 

Figure 7-1 illustrates the Mira 3D Chargeability Model and some of the new targets (blue boxes) at the Cerro Lindo deposit. 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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Figure 7-1: 3D Chargeability Model and New Targets

 

 
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7.1.4 Exploration Target

 

Twenty exploration targets were identified from the integrated assessment of exploration data recorded to date. Targets have been ranked and prioritized using a variety of metrics comprising various geological attributes and modifying factors that have been customized for the mineralization styles most likely to be encountered on the property.

 

In 2019, the diamond drilling program from surface was completed in the Orcocobre, Toldo Grande, and Pucatoro sectors, determining a positive intercept in the area of Pucasalla approximately 4.5 km northwest of the Mine. In August 2019, a total of 48,448.70 m of drilling was performed, including 83 holes.

 

In August 2019, a geology workshop was held with the participation of the Nexa exploration team (Brownfield and Greenfield), external consultants such as Thomas Monecke, Marcelo Imaña, and Les Oldham, APT geologists, and corporate Nexa. As a result, 13 exploration targets were defined. A brief description of each target follows.

 

7.1.4.1 Northwest Extension of OB3-4 and OB12

 

The Northwest extension of OB3-4 and OB12 represents a northwest continuity of OB2B on the other side of the stream. The lithological control of mineralization in this area is associated with volcanoclastic sequences at the edges of the rhyolitic domes. The zone is structurally controlled by northwest-southeast faults. Further exploration is warranted in this zone north of Cerro Lindo

 

7.1.4.2 Pucasalla

 

Pucasalla is located approximately 4.5 km northwest of Cerro Lindo, on the same northwest-southeast trend with the mine. In 2019, drill hole PECLD04226 intersected mineralization with granular barite matrix (SPB) similar to that at Cerro Lindo, which intersected a 6.5 m interval of 3.67% Zn, 0.89% Pb, 0.07% Cu, and 49.47 g/t Ag.

 

7.1.4.3 Cerro Lindo Southeast Extension

 

This zone is the southeast extension of OB6 and OB7 mineralization. Given the presence of a probable rhyolitic dome, the edges of volcanoclastic zones make this zone an important target for exploration.

 

7.1.4.4 Festejo

 

Festejo is located approximately 0.7 km southeast of Cerro Lindo and is a projection of OB6, OB7, and OB9 that are found on the same northwest-southeast trend with the mine. This target represents a strong geophysical anomaly of low resistivity between the 1800 MASL and 2200 MASL elevations.

 

7.1.4.5 Cerro Lindo Deeper Stratigraphic Levels

 

The Cerro Lindo deeper stratigraphic levels are located southwest of OB1. Drill hole PECLDCL-17-2639 intersected a 2.9 m interval of 2.31% Zn and 0.41% Pb at the 1430 m elevation, which indicates that the zone is open to depth. The lithological control is associated with volcanic rocks of dacitic composition.

 
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7.1.4.6 Pucasalla East

 

Pucasalla East is located approximately one kilometre north of Cerro Lindo, northeast of OB3-4 and OB10, on the same northwest-southeast trend with the mine. The lithological control of the mineralization is associated with volcanoclastic sequences at the edges of the rhyolitic domes.

 

7.1.4.7 Ventanalloc

 

Ventanalloc is located approximately 4.5 km north of Cerro Lindo. It has an outcrop of copper oxide (OxCu) and sulphides (pyrite + chalcopyrite). Based on the geological characteristics of the outcrop, Nexa believes Ventanalloc to be porphyry type mineralization. The zone has an area of approximately 1.5 km long by 1.0 km wide and follows the Pucasalla stream to the intersection with the Ventanalloc stream.

 

7.1.4.8 Patahuasi Millay

 

Patahuasi Millay is located approximately 1.2 km northeast of Cerro Lindo, upstream the Topará ravine, where colour anomalies mainly correspond to FeOx (jarosite-goethite). The zone is composed of metamorphosed andesitic volcanics in contact with the Catahuasi intrusive. The area shows weak phyllic alteration with intense silicification, sericite-muscovite inclusions, and disseminated pyrite (5%-10%) and micro-veins.

 

7.1.4.9 Orcocobre

 

Orcocobre is located approximately two kilometres from Cerro Lindo. The target represents an intense colour anomaly corresponding to OxFe (mainly goethite-hematite (boxwork)) with moderate sericitization.

 

7.1.4.10 Toldo Grande

 

Toldo Grande is located approximately four kilometres northwest of Cerro Lindo and is characterized by intense leached silicification and occurrences of barite with a moderate to strong presence of OxFe (goethite-hematite).

 

7.1.4.11 Pucatoro

 

Pucatoro is located approximately five kilometres from Cerro Lindo. The zone is characterized by volcanic felsic rocks, with moderate to intense silicification and silicified disseminated pyrite zones (1%-5%) and sericite.

 

7.1.4.12 Toldo Chico

 

Toldo Chico is located approximately seven kilometres from Cerro Lindo. It consists of several rhyolitic and volcanoclastic sequences at the base and andesitic volcanic sequences at the top in contact with granite Incahuasi intrusives. The zone is characterized by moderate to strong silicification, sericite-muscovite and local barite occurrences, with OxFe (jarosite-goethite) and traces of OxCu and fine pyrite (1%-5%) disseminations.

 

7.1.4.13 Chavin del Sur

 

Chavin del Sul is located approximately seven kilometres southeast of Cerro Lindo. The lithological control of the sphalerite, galena, and chalcopyrite mineralization in this zone is associated with limestone sequences from the upper part of the Huaranguillo Formation. The mineralization is structurally controlled by northeast-southwest and northwest-southeast faults, with the presence of synclines and anticlines. Six historical holes (pre-2009) were completed in this area. Three of them confirmed zinc, lead, and silver mineralization, however, the drill hole database was not available to Nexa.

 
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Exploration work was temporarily suspended from March to June 2020 due to the COVID-19 pandemic. The 2020 exploration diamond drilling confirmed the mineralization continuity of the OB-13 and the OB-14 towards the northwest and also for OB-14 at depth towards the southeast, as well as the upper part of OB-5B between the 1750 and 1950 levels, with an average thickness of 15 m trending northeast. As of December 31, 2020, 62 holes for a total of 23,189 m of diamond drilling were completed during 2020.

 

In 2020, as a result of the 3D chargeability model, in addition to the thirteen exploration targets defined in 2019, a total of seven targets (Mesa Rumi, Festejo Norte, Festejo Sur, Puca Punta, Pucasalla Norte, OB-14 Upper and Pucasalla Sur) were defined. Nexa has developed a prioritized exploration target plan to expand on current Mineral Resources.

 

Figure 7-2 shows the location, the priority and the score-ranking of each of the targets relative to the Mine and Figure 7-3 illustrates a plan view and longitudinal section of some of the exploration targets.

 

Exploration work planned for 2021 includes 35,100 m of diamond core drilling focused on defining Inferred Mineral Resources at six different targets. The main focus of these targets will be the Pucasalla area with a total of 17,100 m of surface drilling and OB-6, OB-5B, OB-12, OB-8, and Patahuasi Millay areas from underground drilling totalling 18,000 m. Work will also include an airborne geophysical VTEM survey, for all the exploration targets, 1:2,000 scale geological surface mapping for Pucasalla, Pucatoro, and Orcocobre over a total of 900 ha, and a geochemical gas sampling survey with 45 collectors, which aims to identify deeply buried mineral deposits, similar to Cerro Lindo, covered by volcanic rocks up to 300 m in depth.

 

In addition to the exploration program, the mining geology team plans to drill an additional 48,000 m with a goal of upgrading Inferred Mineral Resources to Indicated or Measured Resources (recategorization drilling) and ultimately convert them into Probable or Proven Mineral Reserves, and for mine planning purposes (infill drilling).

 

The SLR QP is of the opinion that the geological setting, geophysical studies, surface samples, and geological mapping of the Cerro Lindo area present good exploration potential, as a number of targets have already been identified within a ten kilometre radius of the mining operation. The SLR QP recommends completing the proposed 2021 exploration program including diamond drilling to convert the exploration target to Mineral Resources. The SLR QP is also of the view that there is good potential to increase the Mineral Resource at the Cerro Lindo deposit with more drilling.

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

Technical Report Summary - January 29, 2021

 

            
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Figure 7-2: Brownfield Exploration Targets by Priority 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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Figure 7-3: Brownfield Exploration Targets – Section and Plan View 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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7.2 Drilling

 

7.2.1 Drilling Summary

 

As of March 2, 2020, the Cerro Lindo drill hole database consists of 4,808 drill holes totalling 654,129.63 m (Table 7-3). All drilling was diamond drilling (DDH), with the majority of the holes (4,609) completed underground, from within the mine, and 199 holes completed from surface. Drilling has been done by various contractors

 

Geotechnical holes totalling 3,812.55 m, service holes totalling 944.11 m, geometallurgical holes totalling 100 m, and re-drilled holes totalling 448.20 m have been excluded from the Mineral Resource estimate. SLR concurs with Nexa’s list of holes excluded from the Mineral Resource estimate. Table 7-4 lists the drilling excluded from the Mineral Resource estimate, and Table 7-5 lists the drilling included in the Mineral Resource estimate.

 

In addition to drilling, a total of 1,040 channel samples were completed for a total of 20,682 m between 2000 and 2016 (Table 7-6).

 

Figure 7-4 illustrates the locations of the drill holes at Cerro Lindo. Figure 7-5 is a cross section illustrating the selected drill holes and related geological interpretation and Figure 7-6 shows channel sampling locations at the Mine (2007-2016).

 

From March 3, 2020 to December 31, 2020, an additional 52 exploration drill holes for a total of 19,541.4 m of diamond drilling were completed.

 

Table 7-3:                      Cerro Lindo Drilling Summary as of March 2, 2020 

Nexa Resources S.A. – Cerro Lindo Mine

 

Year   Surface   Mine   Total
  No.   Metres   Type   No.   Metres   Type   No.   Metres   Type
1995*   29   3,550.00   DTH                        
1996   6   2,207.30   DDH   5   2,077.05   DDH   11   4,284.35   DDH
1999   7   2,722.40   DDH   11   2,156.70   DDH   18   4,879.10   DDH
2000   15   5,054.35   DDH   32   6,503.90   DDH   47   11,558.25   DDH
2001   3   705.5   DDH   60   10,663.03   DDH   63   11,368.53   DDH
2007   2   201.35   DDH   42   3,308.60   DDH   44   3,509.95   DDH
2008   25   6,170.24   DDH   61   9,290.60   DDH   86   15,460.84   DDH
2009   17   3,076.40   DDH   173   15,692.30   DDH   190   18,768.70   DDH
2010               183   21,432.61   DDH   183   21,432.61   DDH
2011   5   2,949.20   DDH   177   20,579.10   DDH   182   23,528.30   DDH
2012   8   5,120.40   DDH   82   17,655.90   DDH   90   22,776.30   DDH
2013   2   1,041.10   DDH   306   36,359.00   DDH   308   37,400.10   DDH
2014               253   39,277.80   DDH   253   39,277.80   DDH
2015   15   8,112.40   DDH   368   40,203.00   DDH   383   48,315.40   DDH

  

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

Technical Report Summary - January 29, 2021

 

            
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Year   Surface   Mine   Total
  No.   Metres   Type   No.   Metres   Type   No.   Metres   Type
2016   18   12,270.10   DDH   706   73,233.50   DDH   724   85,503.60   DDH
2017   8   6,050.00   DDH   645   88,140.20   DDH   653   94,190.20   DDH
2018   32   14,956.70   DDH   674   83,170.30   DDH   706   98,127.00   DDH
2019   36   22,463.20   DDH   761   84,227.10   DDH   797   106,690.30   DDH
2020               70   7,058.30   DDH   70   7,058.30   DDH
Total   199   93,100.64       4,609   561,028.99       4,808   654,129.63    

 

Notes:

 

* The down the hole (DTH) drilling carried out in the year 1995 (29 DTH) is not included in the database or estimate because the data is not found.

 

52 exploration drill holes totalling 19,541.4 m completed after March 2, 2020 were not included in the table.

 

Table 7-4:                      Summary of Drilling Excluded from Mineral Resource Estimate as of March 2, 2020 

Nexa Resources S.A. – Cerro Lindo Mine

 

Year   Surface   Mine   Total
  No.   Metres   Type   No.   Metres   Type   No.   Metres   Type
2007               3   254.85   DDH   3   254.85   DDH
2008               3   296.6   DDH   3   296.6   DDH
2009   2   185.10   DDH   16   750.7   DDH   18   935.80   DDH
2010               24   1,019.41   DDH   24   1,019.41   DDH
2011   1   87.4   DDH   15   917.20   DDH   16   1,004.60   DDH
2012   2   190.70   DDH   6   1,032.30   DDH   8   1,223.00   DDH
2013   1   41.10   DDH           DDH   1   41.10   DDH
2014               2   214   DDH   2   214   DDH
2015               2   100   DDH   2   100   DDH
2016               2   130.5   DDH   2   130.5   DDH
2018               2   85   DDH   2   85   DDH
Total   6   504.30       75   4,800.56       81   5,304.86    

 

Note. The drilling was excluded due to the absence of assay results, either because this was twin hole drilling, or drilling for geomechanical, geometallurgical, and service (installation of pipes, etc.) purposes.  

 
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Table 7-5:                      Summary of Drilling Included in Mineral Resource Estimate as of March 2, 2020 

Nexa Resources S.A. – Cerro Lindo Mine

 

Year   Surface   Mine   Total
  No.   Metres   Type   No.   Metres   Type   No.   Metres   Type
1996   6   2,207.30   DDH   5   2,077.05   DDH   11   4,284.35   DDH
1999   7   2,722.40   DDH   11   2,156.70   DDH   18   4,879.10   DDH
2000   15   5,054.35   DDH   32   6,503.90   DDH   47   11,558.25   DDH
2001   3   705.5   DDH   60   10,663.03   DDH   63   11,368.53   DDH
2007   2   201.35   DDH   39   3,053.75   DDH   41   3,255.10   DDH
2008   25   6,170.24   DDH   58   8,994.00   DDH   83   15,164.24   DDH
2009   15   2,891.30   DDH   157   14,941.60   DDH   172   17,832.90   DDH
2010               159   20,413.20   DDH   159   20,413.20   DDH
2011   4   2,861.80   DDH   162   19,661.90   DDH   166   22,523.70   DDH
2012   6   4,929.70   DDH   76   16,623.60   DDH   82   21,553.30   DDH
2013   1   1,000.00   DDH   306   36,359.00   DDH   307   37,359.00   DDH
2014               251   39,063.80   DDH   251   39,063.80   DDH
2015   15   8,112.40   DDH   366   40,103.00   DDH   381   48,215.40   DDH
2016   18   12,270.10   DDH   704   73,103.00   DDH   722   85,373.10   DDH
2017   8   6,050.00   DDH   645   88,140.20   DDH   653   94,190.20   DDH
2018   32   14,956.70   DDH   672   83,085.30   DDH   704   98,042.00   DDH
2019   36   22,463.20   DDH   761   84,227.10       797   106,690.30    
2020               70   7,058.30   DDH   70   7,058.30   DDH
Totals   193   92,596.34       4,534   556,228.43       4,727   648,824.77    

 

Note. For the Leapfrog model all validated drill holes were used.

 

Table 7-6:           Channel Sampling Summary at Cerro Lindo 

Nexa Resources S.A. – Cerro Lindo Mine

 

Year   No.
Channels
  Metres
<2008   506   10,278.50
2008   13   168.30
2010   108   2,698.30
2011   93   1,301.30
2012   113   2,031.10
2013   58   1,162.50

 

 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

Technical Report Summary - January 29, 2021

 

            
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Year   No.
Channels
  Metres
2014   71   1,487.90
2015   57   1,086.70
2016   21   468.00
Total   1,040   20,682.60

 

 
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Figure 7-4: Drill Hole Location 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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Figure 7-5: Schematic of Selected Drilling and Related Geological Interpretation 

 
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Figure 7-6: Location of Channel Sampling (2007-2016) 

 
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7.2.2 Drilling Procedures

 

Drilling procedures are coordinated and supervised by company geologists, and approved by the Geology and Exploration Manager. The drilling procedures are as follows:

 

Diamond drilling projects are prepared by geologists. Drill hole collar coordinates and orientation are communicated to a mine surveyor to accurately position the drill hole and are then certified by the surveyor and validated by the responsible geologist. Hole (and channel sample) IDs are generated using a specific format, which includes the following reference codes: country, mining unit, year, and sequential number. All related drill data generated is referenced similarly to the corresponding drill collar. Basic drill hole information must be entered into the database and archived within four days of completing the drill hole.

Drill hole survey data is collected by the drilling contractor. The survey is generally carried out after the completion of the drill hole. Various survey equipment (i.e., Gyro, Reflex, Flexit, etc.) may be used depending on the drilling contractor and equipment availability.

Survey data are collected between approximately 5 m and 10 m down hole, depending on the drilling objective (infill or recategorization). Original survey data is delivered to the supervising geologist, signed by the driller in charge. Survey data is validated by the responsible geologist and entered into a master CSV file, subsequently imported into the database and the geological modelling software program.

Following the completion of a drill hole, logging and core sampling procedures are carried out by a team of geologists. Core logging is carried out using a set of geological, lithological, mineralogical, and alteration terms. Core logs are entered into logging software (Fusion). Core photographs are taken for each drill hole and stored in jpeg. Core sampling for geochemical analysis is generally completed at the same time as core logging. Logging is completed within 48 hours after a drill hole is completed.

Datamine’s Fusion software (Fusion) managing the database automatically incorporates the core logging and sampling information and continually updates this information with new results. The database administrator is responsible for validating the data and combining it into a master CSV file, for later imports into geological modelling software programs.

Drilling information is stored in a structured directory and backed up on a central server in Brazil. Data available in the drill hole database includes: hole location (Collar), hole deviation survey (Survey), geochemical sampling and analysis (Assay), and geological characteristics (Lithology, Alteration, Mineralization).

 

7.2.3 Drill Rigs

 

At Cerro Lindo, there are two main categories of drilling: exploration and resource definition diamond drilling. Drilling is performed by Explomin contractor.

 

7.2.3.1 Exploration Diamond Drilling

 

Exploration drilling is planned by the exploration team and its main objective is to discover new resources. It consists of underground (mine) drilling and surface drilling using Sandvik DE140 and Boart Longyear LF 90 drilling machines respectively. Exploration drilling is carried out with large drill rigs with a depth range of up to 1,000 m and HQ (63.5 mm) and NQ (47.6 mm) core sizes, and as required BQ (36.6 mm), are used.

 

 
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7.2.3.2 Resource Definition Diamond Drilling

 

Resource definition drilling is the responsibility of the geological team and has the objective to upgrade known Inferred Mineral Resources to Measured or Indicated and thus increase the Mineral Reserves at Cerro Lindo. This drilling consists of:

 

Recategorization, focused on the recategorization and definition of bodies where there is little drilling information.

 

lnfill, focused on providing additional information for short to long term planning to ensure the reliability of production programs.

 

Small drill rigs called drillcats are used with depth ranges of up to 400 m. Infill drilling generally uses BQ core size (to a depth of 240 m) and recategorization drilling uses NQ or BQ core size (to a depth of 400 m).

 

7.2.4 Core Recovery

 

Core recovery and rock quality designation (RQD) are measured and recorded for each hole. Core runs are 3.0 m for HQ and NQ and 1.5 m for BQ core size. Measurements are reviewed by geologists and the database administrator and then imported to the Fusion database.

 

Table 7-7 summarizes core recovery by domain in 2019 and 2020.

 

Table 7-7:           Core Recovery by Domain - 2019-2020

Nexa Resources S.A. – Cerro Lindo Mine

 

Domain   No.
Samples
  Minimum
(%)
  Maximum
(%)
  Mean
(%)
  Variance   Std. Deviation   CV
SPB   5,053   0.00   100.00   96.795   146.007   12.083   0.125
SPP   11,664   0.00   100.00   96.475   100.099   10.005   0.104
SSM   5,675   10.00   100.00   98.795   20.097   4.483   0.045
VM   3,612   0.00   100.00   98.273   36.446   6.037   0.061
V   1,570   10.00   100.00   97.177   95.379   9.766   0.100
SOP   68   90.00   100.00   97.964   5.469   2.338   0.024
SOB   31   45.00   100.00   95.215   194.915   13.961   0.147
SLB   19   72.22   100.00   95.744   70.013   8.367   0.087
OB11VM   5   96.88   100.00   99.501   1.308   1.144   0.011
OB12VM   74   60.00   100.00   99.523   4.928   2.220   0.022
OB14VM   118   85.00   100.00   98.996   3.131   1.769   0.018
OB5BVM   56   70.56   100.00   99.121   16.561   4.070   0.041
PUCVM   11   98.39   100.00   99.698   0.265   0.515   0.005
DIQUE   8,945   5.33   100.00   98.920   22.964   4.792   0.048

 

Notes: 

Data encoded within the model. 

For this analysis, 1,825 of 4,808 drill holes (38%) were used.

 
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Based on core recovery statistics reviewed, and from the inspection of a number of drill holes, the SLR QP is of the opinion that the core recovery at Cerro Lindo is excellent, generally greater than 95%, and provides a reliable reflection of the mineralization in the mining operation.

 

7.2.5 Drill Hole Spacing

 

Exploration drilling is generally completed over an 80 m by 80 m grid, whereas infill drilling is designed to cover a 20 m by 20 m grid.

 

7.2.6 Drill Core Sampling

 

7.2.6.1 Phelps Dodge

 

Core was sampled every two metres over the length of the hole and split using a diamond saw. Half of the core was submitted for assaying and the other half was stored at the site.

 

7.2.6.2 Nexa

 

The sample interval was initially 1.5 m to 2.0 m, except when encountering lithological, structural, or mineralogical breaks. All sulphide material was sampled, and additional “bracket” samples were taken on either side in the surrounding volcanic rocks, which ensured that the entire mineralized zone was sampled and provided data for dilution analysis (AMEC, 2002).

 

Drill core sampling is carried out under the supervision of the Sampling Geologist Supervisor and completed after the geotechnical and geological logging, and photographing the whole core. Once the sample length and cut-line have been defined by the supervising geologist, the core is cut longitudinally into two equal parts using an electric diamond drill core saw. If the core is fractured, the sampler separates and removes 50% of the fragmented material for the sample. The fragments are deposited in a pre-coded polyethylene bag and transported to the laboratory.

 

Current exploration core sampling follows written protocols and consists of half-core sampling of NQ-sized core on (usually systematic) 1.5 m intervals. The remaining half-core is kept as backup. Major mineralized body contacts are respected.

 

Infill drilling is typically B-sized core and is sampled in its entirety on 1.6 m intervals.

 

7.2.7 Underground Channel Sampling

 

Channel sampling was carried out from 2000 to 2016. The channel sampling procedure remained the same over these years, and the procedure is described in formal protocols. Samples were collected from cross-cuts, perpendicular to strike, and from both mineralized and barren zones (footwall and hanging wall).

 

Sample locations were marked with a paint line on the rib approximately one metre off the drift floor. Channel borders were then cut using an electric diamond saw, after which the samples were collected using a pneumatic or electric hammer or, rarely, a chisel and hammer between the cut borders. Samples were collected in a bucket with minimal loss of sample. Channel samples were 1.5 m long, 6 cm wide and 3 cm deep, with sample weight ranging from 4 kg to 8 kg (in barren zones, less than 4 kg). All cross-cuts were channel sampled, with the exception of those portions covered by shotcrete for safety purposes. In those cases, short infill holes were drilled instead.

 

 
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AMEC observed channel sampling in early 2016. The channel sampling was discontinued and replaced by additional drilling later in 2016.

 

7.2.8 Underground Longhole Sampling

 

Upward oriented blast holes were sampled until late 2016. The drill cuttings produced from every 1.5 m long advance were collected in buckets and submitted to the laboratory for assaying.

 

Blast hole fans, consisting of 17 holes, were drilled every 2.2 m of drift advance. One in three face advances (every 6.6 m) was fully sampled, and the samples were submitted to the Mine laboratory for preparation and analysis. Underground longhole sampling, together with channel sampling, was used for ore control but was discontinued in 2016.

 

7.2.9 Drilling and Channel Sampling Results

 

The results of analysis and interpretation of drilling data, and prior to 2016 channel sampling data, have been continually incorporated into the Cerro Lindo 3D geological model.

 

The database is used by modelling geologists who work together with the mine/production and exploration geologists to continually construct and update the 3D geological model. The 3D geological models are built in Leapfrog, primarily using geochemical assay results, particularly for Zn, Pb, Cu, and Ag, as well as underground geological level plan maps and interpreted cross-sections and transverse sections.

 

In the SLR QP’s opinion, the drilling, logging, and drill core and channel sampling procedures meet industry standards. The SLR QP is not aware of any drilling, sampling, or recovery factors that could materially impact the accuracy and reliability of the results.

 

7.3 Hydrogeology

 

The Cerro Lindo is a relatively dry mine and does not produce significant quantities of water. Exploration drilling to date has not intersected any water bearing structures that could introduce major inflows in the mine workings.

 

7.4 Geotechnical Data, Testing, and Analysis

 

Geotechnical studies have been conducted at the Cerro Lindo Mine to prepare a geotechnical model of ground conditions and to characterize the quality of the rock mass to predict the stope and mine workings stability. Underground geotechnical mapping, geotechnical core logging and laboratory tests are part of Nexa geotechnical procedures. Since 2007, Nexa has performed laboratory testing in combination with geotechnical mapping and since 2015 geotechnical logging to monitor the ground stability and to define parameters for ground support design of the underground workings. Independent geotechnical assessments were performed by AMEC in 2013 and SRK in 2016 and 2017. In 2017, SRK completed a 3D numerical model using the FLAC3DTM 5.01 software (Itasca Consulting Group) as it is described in Section 13.4. The geotechnical logging, mapping, testing and data analysis protocols include industry-standard practices.

 

7.4.1 Geotechnical Data

 

As of December 31, 2020, Nexa performed a total of 492 geotechnical drill holes totaling 23,473.20 m (Table 7-8). In addition, geotechnical logging and mapping of the underground workings are also conducted in a routine basis.

 

 
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The geotechnical logging includes the rock mass rating classification systems developed by Bieniawski (1976 and 1989). These classification systems are widely used empirical methods for classifying the rock mass quality and internationally accepted practice. Data collection of detailed rock mass characteristics (lithology, faulting and shearing, intact rock strength, Rock Quality Designation (RQD), discontinuity characteristics such as openness/aperture, planarity, roughness, infilling/coating and evidence of groundwater staining). During 2020, Nexa transferred the geotechnical database from Excel files to Fusion software.

 

Table 7-8:                     Geotechnical Drilling - 2015-2020 

Nexa Resources S.A. – Cerro Lindo Mine

 

Year   Mine
  No.   Metres   Type
2015   13   808.20   DDH
2016   6   271.60   DDH
2017   48   1765.30   DDH
2018   65   4465.50   DDH
2019   119   6503.60   DDH
2020   241   9659.00   DDH
Total   492   23,473.20    

 

For the 2017 geotechnical study, SRK re-logged 35 drill holes totaling 2,402 m. Selected drill holes were located on the mining production areas ( OB-1, OB-4 and OB-6) and were used to obtain geomechanical characterization, using the RMR’89 and the Modified Rock Quality Index (Q’) systems, for the modelled lithology units in the mine. In addition, geological mapping was performed to define the main fault systems. Point load testing was also conducted with a portable device during the geotechnical logging and mapping. As the selected holes were drilled for resource estimation purpose, only half of the core was available, so core photographs and software (PhotoLogger and StereoCore PhotoLog) were used to measure fracture frequency and intensity. Figure 7-7 illustrates the RQD and RMR collected from the study. 

 
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Figure 7-7: Histograms of RDQ and RMR

 

7.4.2 Testing and Analysis

 

In 2017, SRK collected core and rock samples for laboratory strength testing. Testing was performed at the SRK laboratory and comprised: 216 Uniaxial Compressive Strength (UCS) tests, and six physical properties tests including density, granulometry and soil tests. Table 7-9 and Table 7-10 list the results of the physical property and load tests respectively. 

 
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Table 7-9:                    Physical Property Test 

Nexa Resources S.A. – Cerro Lindo Mine

 

No   Lithology   Sample   Dry Density
(gr/cm3)
  Saturated Density
(gr/cm3)
  Apparent Porosity
(%)
  Absorption
(%)
1   SSM   1   2.64   2.67   2.96   1.12
2   SSM   2   2.64   2.67   2.75   1.04
3   Enclave   1   2.63   2.66   3.6   1.37
4   Enclave   2   2.63   2.66   2.66   1.19
5   SLB   1   2.65   2.69   3.53   1.33
6   SLB   2   2.64   2.68   3.77   1.43

Source: SRK 2017

 

Table 7-10:           Load Testing 

Nexa Resources S.A. – Cerro Lindo Mine

 

Lithology   Is (50)   Conversion Factor   UCS
(MPa)
     
SPP   1.77   19   34
SPB   2.41   35   84
SSM   5.05   24   121
Volcanic Rocks   8.24   21   173
Dike   10.21   15   153
Enclave   2.8   24   67
SLB, SOB, SOP   1.9   24   46
Source: SRK 2017            

 

In 2019 and 2020 Nexa carried out laboratory testing to determine the mechanical properties such as uniaxial compressive strength, triaxial compressive strength, indirect tensile strength, elastic moduli of intact rock, and pulse velocities and ultrasonic elastic constants, to monitor the ground stability and to define parameters for ground support design of the underground workings and main infrastructure. All testing was completed using norms such as the ASTM (American Society of Testing and Materials), IRMS (International Rock Mechanics Society), and AAMR (American Association of Rock Mechanics) in accordance with best practices. The most recent laboratory testing was carried out in 2019 by Geomecánica Latina S.A., with offices in Peru, Bolivia, and Chile.

 

In the SLR QP’s opinion, the geotechnical drilling, logging, mapping and testing procedures meet industry standards. The SLR QP is not aware of any geotechnical drilling, logging, mapping, and testing that could materially impact the accuracy and reliability of the results.

 
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8.0 Sample Preparation, Analyses, and Security

 

8.1 Density Determinations

 

Density and/or specific gravity (SG) data have been collected by Nexa and predecessors throughout the history of the project. It is not clear from the record which data type was actually collected. Density is a measure of the mass per unit volume of a material. In the case of geological materials, SG is the unitless ratio of the density of the sample to the density of water. At a water temperature of 4°C, the numerical value of density and SG for a given sample is exactly equal. At any other temperature, the values are different, however, for temperatures of less than 40°C, the discrepancy is in the third or fourth decimal place and is thus well within anticipated errors of the methodology. For that reason, density in g/cm3 and SG are typically used interchangeably and not reported separately. In the case of Cerro Lindo, both density and SG data have been collected and used as “density” results. The errors introduced are very small and will not affect Mineral Resource estimation. For simplicity, SLR accepts the use of the term “density” for both density and SG data in this discussion.

 

AMEC (2002) reported that intervals of diamond drill core were used to obtain density information by rock type for approximately 3,000 samples prior to 2002. Bondar Clegg in Lima produced the initial bulk density determinations using the standard water-displacement method on wax-coated core.

 

Additional sampling and measurements were completed at site by Milpo, using the water-displacement method, but without wax coating. The suitability of these measurements was verified by testing 135 samples previously submitted to Bondar Clegg. Those data were excluded from the current Mineral Resource estimate, as they were later determined by Milpo to be suspect.

 

Beginning in 2013, a new sampling campaign was initiated to update, and improve, the density database. Milpo and Nexa collected 8,524 samples from underground drill holes and drift walls and submitted them to an external laboratory (Certimin or Inspectorate) for SG determinations using the water-displacement method with wax-coated core. Of these, 4,410 samples were located in the mineralization domains (Figure 8-1) and 4,114 samples were located in the wallrock. A buffer of 20 m was used to select and review the density data in the wallrock totalling 1,215 density measurements.

 

Table 8-1 summarizes the density measurements by sample type and year. The 2020 mean and median density data by domain are summarized in Section 11, Mineral Resource Estimate (Bulk Density).

 

Table 8-1:           Number of Density Measurements by Sample Type and Year 

Nexa Resources S.A. – Cerro Lindo Mine

 

Phase   Sample Type   No. Samples   No. Samples within
Mineralization Zones
CL2013   Drift Walls   84   59
  Drill Holes   53   20
CL2014   Drill Holes   197   133
CL2015   Drill Holes   451   353
CL2016   Drill Holes   546   445
CL2017   Drill Holes   1,127   927

 
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Phase   Sample Type   No. Samples   No. Samples within
Mineralization Zones
CL2018   Drill Holes   3,349   1,286
CL2019   Drill Holes   2,191   882
CL2020   Drill Holes   526   305
Total   Drill Holes   8,524   4,410

 

Note. In addition, there are 1,215 density measurements in wallrock (20 m buffer zone) used in the resource estimate.

 
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Figure 8-1: Distribution of Density Samples used for 2020 Mineral Resource Estimate by Year Analyzed

 
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8.2 Analytical and Test Laboratories

 

No details were available regarding laboratory procedures prior to the Milpo 1999 drilling campaign, including the Phelps Dodge drill program.

 

Samples from drilling and underground sampling programs completed by Milpo from 1999 to 2001 were prepared at the Bondar Clegg facility in Lima and analyzed at the Bondar Clegg laboratory in Bolivia (AMEC, 2002). Bondar Clegg’s laboratories in Lima and Bolivia were not certified; however, both followed protocols set out by Bondar Clegg’s Vancouver laboratory, which had ISO 9001 certification.

 

The check or umpire laboratory used was SGS Lima (SGS), which was an ISO 9001 certified laboratory.

 

Starting in 2007 until the beginning of October 2019, all mine samples were processed at the Cerro Lindo Mine laboratory (Mine Laboratory), which was managed by SGS between 2007 and 2011 and since 2011, by Inspectorate. The Mine Laboratory shut down due to lack of capacity at the beginning of October, and since that time, mine samples have been sent to Inspectorate Lima. From 2014 to 2016, exploration samples were processed at Inspectorate Lima, however, that laboratory was replaced in early 2016 by Certimin Lima. In late 2019, ALS Lima was also retained by Nexa to process exploration samples.

 

During the 2018 to 2019 drilling campaign, ALS Lima was used as a secondary laboratory for external check for mine and exploration samples.

 

Inspectorate Lima has ISO 9001, ISO 14001, and ISO 19007 certification. Certimin Lima holds ISO 9001 and NTP-ISO/IEC 17025 and 17021 certifications and is accredited by the Organismo Peruano de Acreditación (INACAL). ALS geochemical laboratories are accredited to ISO/IEC 17025:2005 for specific analytical procedures. Both Certimin and ALS laboratories are independent of Nexa.

 

The Mine Laboratory was neither certified nor accredited.

 

Table 8-2 summarizes the laboratories used for preparation and analysis of exploration and mine samples at Cerro Lindo since 1999.

 

Table 8-2:           Analytical and Test Laboratories 

Nexa Resources S.A. – Cerro Lindo Mine

 

Laboratory Name   Location   Period of Use   Comments   Certified/Accredited   Independent
Bondar Clegg   Lima   1999–2001   Preparation of drilling and underground samples. Protocols set out by Bondar Clegg Vancouver, which is ISO 9001 accredited.   Not accredited   Yes
Bondar Clegg   Bolivia   1999–2001   Drilling and underground sample analyzed. Protocols set out by Bondar Clegg Vancouver which is ISO 9001 accredited   Not accredited   Yes
SGS   Lima   1999–2001   Check laboratory   ISO 9001   Yes
Mine Laboratory   Cerro Lindo site   2007–2011   Processing of all mine samples. Managed by SGS.   No   No
 
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Laboratory
Name
  Location   Period
of Use
  Comments   Certified/Accredited   Independent
Mine Laboratory   Cerro Lindo site   2011–2020   Processing of all mine and process samples. Managed by Inspectorate Lima.   No   No
Inspectorate   Lima   2014–2016   Processing of exploration samples   ISO 9001
ISO 14001
ISO 19007
  Yes
Certimin   Lima   2016–2019   Processing of exploration samples   ISO 9001
NTP-ISO/IEC 17025
and 17021 Accredited by Organismo Peruano de Acreditación INACAL
  Yes
Inspectorate   Lima   2019– 2020   Primary laboratory for mine samples   ISO 9001
ISO 14001
ISO 19007
  Yes
ALS   Lima   2019-2020   Processing of exploration samples   ISO 9001   Yes

 

8.3 Sample Preparation and Analysis

 

8.3.1 Geochemical Samples

 

Lithogeochemical samples collected by Imaña (2015) were analyzed at ACME Laboratories Vancouver using lithium metaborate fusion and inductively coupled plasma mass spectrometry (ICP-MS) for major oxides and for refractory and rare-earth elements. An ICP-MS package with multi-acid digestion was used to analyze other elements. Additional details regarding geochemical sample preparation and assaying during this study were not available.

 

8.3.2 Exploration Samples

 

The sample preparation procedure at Bondar Clegg Lima involved the following steps (Figure 8-2; AMEC, 2002):

 

Jaw-crushing to 2 mm (10 mesh ASTM)

Homogenization and splitting to obtain a 250 g sub-sample using a Jones splitter

Pulverizing the sub-sample to 90% minus 0.106 mm (150 mesh Tyler).

 

Samples were assayed at Bondar Clegg Bolivia for silver, copper, lead, zinc, and gold. No details were available regarding the assay methods.

 
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Note: Figure prepared by AMEC, 2002.

 

Figure 8-2: Sample Preparation and Quality Control Flowsheet (Milpo 2000–2001 Program)

 

Since 2007, exploration samples sent to Certimin, Inspectorate, and ALS Lima have been prepared using the same procedure used by the Mine Laboratory discussed in the following section. Analyses of silver, zinc, copper, and lead are performed by four-acid digestion followed by atomic absorption spectroscopy (AAS). A four-acid digestion followed by ICP optical emission spectrometry (ICP-OES) analysis is used for multielement analyses on all samples.

 

8.3.3 Mine Samples

 

Since 2007, sample preparation of geological samples at the Mine Laboratory and currently Inspectorate Lima has followed the procedure:

 

Drying at 105°C ± 5°C in stainless steel trays.

Primary crushing to 3/4” using a Rhino jaw crusher.

Secondary crushing to better than 85% minus 2 mm (10 mesh ASTM) using a RockLabs jaw crusher. A Boyd crusher with a dedicated rotary splitter was acquired in 2016 and is now in service.

Homogenization and splitting to obtain a 200 g to 250 g sub-sample using a Jones splitter with 28 one-centimetre wide chutes. The dedicated rotary splitter attached to the Boyd crusher is now used.

Pulverizing the collected sub-sample to 95% minus 0.105 mm (140 mesh ASTM) in a TM Andina™ ring pulverizer.

 

Geological samples average 3 kg to 5 kg. All preparation workstations are provided with compressed air hoses for cleaning and dust extraction. Sieve checks are conducted on 3% of randomly chosen crushed and pulverized samples, however, only one set of checks (the first one) is formally recorded every day. Results are posted in the laboratory for all personnel to review.

 
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Geological samples are assayed for silver, copper, lead, zinc, and iron using 0.25 g aliquots, aqua regia digestion, and AAS determination. Detection limits for the Mine Laboratory, Inspectorate Lima, Certimin Lima, and ALS Lima are summarized in Table 8-3.

 

Table 8-3:           Detection Limits at Mine Laboratory, Inspectorate Lima and Certimin Lima 

Nexa Resources S.A. – Cerro Lindo Mine

 

Laboratory   Detection Limit
  Ag (ppm)   Cu (%)   Pb (%)   Zn (%)   Fe (%)
Mine Laboratory   0.4   0.01   0.01   0.01   0.01
Inspectorate Lima   1.0   0.01   0.01   0.01   0.01
Certimin Lima   0.2   0.00005   0.0002   0.00005   0.01
ALS Lima   0.01   0.00002   0.001   0.0002   0.01

 

Laboratory personnel collect samples manually from various positions in the process flow to determine the head, concentrate, and tailing grades in 12-hour composites. The high grade concentrate samples are prepared at separate facilities from the exploration samples to avoid possible contamination of lower grade samples. Tailings are assayed using procedures similar to those for geological samples with concentrates requiring the use of volumetric methods for copper, lead, and zinc due to the higher grades.

 

The Mine Laboratory used a proprietary Global Laboratory Information Management System (GLOBAL LIMS) for digitally registering all measurements (including scale weights), without any human intervention in the data flow. The LIMS determines the position where control samples must be inserted, and assesses the results of the QC, indicating if those results are acceptable or not. Acceptable results are then directly transferred into the mine database.

 

8.4 Sample Security

 

Core boxes are transported every day to the core shed by personnel from the drilling company. Analytical samples are transported by company or laboratory personnel using corporately owned vehicles. Core boxes and samples are stored in safe, controlled areas.

 

Chain-of-custody procedures are followed whenever samples are moved between locations, to and from the laboratory, by filling out sample submittal forms.

 

In the SLR QP’s opinion, the sample preparation, analysis, and security procedures at Cerro Lindo are adequate for use in the estimation of Mineral Resources.

 

8.5 Quality Assurance and Quality Control

 

Quality assurance (QA) consists of evidence to demonstrate that the assay data has precision and accuracy within generally accepted limits for the sampling and analytical method(s) used in order to have confidence in the resource estimation. Quality control (QC) consists of procedures used to ensure that an adequate level of quality is maintained in the process of sampling, preparing, and assaying the drill core samples. In general, QA/QC programs are designed to prevent or detect contamination and allow analytical precision and accuracy to be quantified. In addition, a QA/QC program can disclose the overall sampling – assaying variability of the sampling method itself.

 
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At Cerro Lindo, QC samples have been inserted into the sample stream since 1996 and channel samples since 2012. The Mine routinely sends in-house certified reference materials (CRMs), blanks, field (twin), coarse reject, and pulp duplicates, and external checks for analysis. Prior to Nexa’s drilling campaigns, standard reference materials (SRM) were used, however, during 2017, Nexa replaced SRMs with CRMs. No SRMs or blanks were submitted during the 1999-2001 Phase 1 drilling campaign. In 2018, Nexa incorporated systematic external checks into the QA/QC program, and pulps have since been sent to external laboratories for analysis. Currently, Inspectorate Lima analyzes samples from infill drilling and Certimin and ALS Lima analyze samples from brownfield exploration drilling.

 

8.5.1 Phelps Dodge, 1996-1997

 

This section has mostly been taken from AMEC (2017).

 

The Phelps Dodge drilling campaign included a thorough QC program, including the use of blanks, standards, and duplicates. AMEC (2002) reviewed the results for all zinc values greater than 1% and concluded that this work was completed to an acceptable industry standard.

 

8.5.2 Milpo, 1999–2016

 

This section has mostly been taken from AMEC (2017).

 

From 1999 to 2001, a QC program was put in place during the feasibility study (AMEC, 2002). During Phase 1, the program did not include SRMs or blanks, however, samples were submitted for external control to SGS. Zinc data showed acceptable analytical performance.

 

During Phases 2 and 3, the program included the insertion of SRMs and coarse blanks as well as coarse reject and pulp duplicates. AMEC (2002) summarized the results as follows:

 

Copper and zinc SRMs were submitted with every batch and results were within control limits. The copper accuracy was adequately controlled.

Check assays of copper and zinc show satisfactory agreement and no apparent bias.

No significant copper and/or zinc contamination during sample preparation and assaying was identified.

Coarse duplicate samples met acceptable criteria. The sample preparation protocol appeared to be adequate.

 

From 2007 to 2012, AMEC (2010, 2012, and 2013) and Snowden (2008 and 2011) reviewed the QC protocol implemented at the time. The protocol included the insertion of quarter-core twin samples, twin channel samples, coarse and pulp duplicates, two SRMs for core samples and one SRM for channel samples, and coarse blanks. The insertion rates were not specified. AMEC (2013) concluded that:

 

Sampling precision for zinc, copper, lead, and silver was within or close to acceptable limits, however, AMEC (2013) recommended that twin samples be collected from the remaining half-core rather than quarter-core.

Sub-sampling precision for zinc, lead, and silver was within acceptable limits, while the copper error rate exceeded the limits.

Analytical precision was poor for zinc, copper, and silver, and acceptable for lead.

Accuracy was monitored using SRMs documented on a limited inter-laboratory test. Although biases appeared to be reasonable for the two SRMs used on core sample submissions, AMEC (2013) recommended that SRMs be better documented by analysis at additional laboratories. Data from the SRM used for channel sample submissions were not presented.
 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

Technical Report Summary - January 29, 2021

 

            
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Blank samples did not indicate the presence of significant contamination during preparation and/or assaying.

 

During the 2014 and 2015 drilling campaigns, Milpo (2016a, 2016b) implemented a QC program for channel and core samples, which was similar to the program implemented in 2012 and 2013 (AMEC, 2013). During 2015, 975 channel samples (including 183 control samples) were submitted to the laboratory. The overall insertion rate for QC samples was 19.2%. Conclusions included:

 

Sampling and sub-sampling precision for lead and silver were within acceptable limits (10%), however, failure rates for copper for all duplicates and for zinc for twin samples and coarse duplicates considerably exceeded the acceptable limits. This may be the result of poor sampling practices, although Milpo (2016a) suggested that the practical lower detection limit was actually higher than believed by the laboratory. If so, the actual failure rates could be lower.

Most SRMs exhibit bias values within or relatively close to the acceptable limits (±5%). Only MCL-03 Certimin for copper produced a very high positive bias, however, due to the very low copper grade of the MCL-03 SRM for copper (0.04%), AMEC recommended not using it as an SRM for copper. Low coefficients of variation (not exceeding 2.3%) suggest good analytical precision at those grade levels for all elements.

Based on the results of the coarse blank data, no significant contamination during preparation or assaying occurred.

 

The 2016 QA/QC protocol included inserting one coarse blank, one SRM, one twin sample, one coarse duplicate, and one pulp duplicate in every 25-sample batch. The coarse blank material is obtained from a nearby granodiorite pit. A total of 4,934 QA/QC samples were inserted into the sample stream at an overall insertion rate of 17.50%. AMEC reviewed the monthly reports and QC data and concluded the following:

 

Duplicate failure rates were usually below or very close to the industry accepted limits. Therefore, sampling, sub-sampling, and analytical precisions were generally within acceptable limits.

Most bias values lay within the acceptable ±5% range, however, high grade zinc values were, on average, underestimated by approximately 8% from January to March 2017. The underestimation returned to an acceptable level in April 2017.

Most coefficients of variations were below 5% suggesting good analytical precision. This was in agreement with pulp duplicate data.

No significant contamination during preparation or assaying was identified for any of the studied elements.

 

QA/QC sample insertion rates from 2014 to 2016 are listed in Table 8-4. The 2014 to 2016 QA/QC program details, for the Mine, Inspectorate Lima, and Certimin laboratories, are summarized in Table 8-5. The method of analysis used was aqua regia with an AAS finish (Ag, Cu, Pb, and Zn).

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

Technical Report Summary - January 29, 2021

 

            
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Table 8-4:           QA/QC Sample Insertion Rates, 2014-2016 

Nexa Resources S.A. – Cerro Lindo Mine

 

Control Sample Type   No. Samples   Insertion Rate (%)
Blanks   Coarse   1,765   3.69%
Standards   Low grade (STD1-STD4)   471   0.99%
  Medium grade (STD2)   409   0.86%
  High grade (STD3-STD5)   837   1.75%
Duplicates   Field Duplicate   1,749   3.66%
  Coarse Duplicate   1,792   3.75%
  Fine Duplicate   1748   3.66%
Total       8,771   18.35%

 

Table 8-5:           2014-2016 QA/QC Program Summary 

Nexa Resources S.A. – Cerro Lindo Mine

 

                    Bias (%)
Laboratory   QA/QC Sample   Type   No. Samples  

Failure

Límit (%)

  Ag   Cu   Pb   Zn
Mine Laboratory   Blanks   Coarse   1751   <5%   0.04%   0.18%   0.22%   0.22%
  Standards   STD1,2,3   1626   <5%   0.43%   0.81%   -3.61%   -4.51%
  Duplicates   Field Dups   1706   <10%   2.10%   6.34%   3.40%   5.39%
    Coarse Dupl   1749   <10%   3.71%   6.15%   3.60%   7.69%
    Fine Dupl   1706   <10%   1.85%   2.76%   1.54%   4.35%
Inspectorate (Lima)   Blanks   Coarse   41   <5%   0.00%   0.00%   0.00%   0.00%
  Standards   STD4,5   66   <5%   7.90%   2.00%   2.20%   -2.40%
  Duplicates   Field Dupl   43   <10%   0.00%   0.00%   0.00%   0.00%
    Coarse Dupl   43   <10%   0.00%   0.00%   0.00%   0.00%
    Fine Dupl   42   <10%   0.00%   0.00%   0.00%   0.00%
Certimin   Standards   STD4,5   43   <5%   3.90%   2.80%   -6.40%   0.70%
Total           8,771                    

 

8.5.3 Nexa, 2017-2020

 

The following QA/QC protocols are in place at the Mine. Currently, the primary laboratory for preparation and analysis of the infill drilling (mine) samples is Inspectorate Lima. Prior to October 2019, the mine samples were prepared and analyzed at the Mine Laboratory (Inspectorate Mine). For brownfield exploration drilling (exploration) samples, the primary laboratories have been Certimin and ALS Lima. The secondary laboratories, used for external check for mine and exploration samples during the 2018 to 2019 drilling campaign, was ALS. During the 2019 to 2020 drilling campaign (Nexa, 2020c), Nexa collected part of the check samples, however, these were not sent to the secondary laboratory as mining activities were interrupted due to COVID-19 restrictions.

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

Technical Report Summary - January 29, 2021

 

            
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8.5.3.1 QA/QC Protocols

 

Nexa has the following QA/QC protocols in place.

 

For infill drilling, each batch of 50 samples submitted for sample preparation and analysis includes 42 regular samples, two CRM samples, two coarse blank samples, two coarse duplicates, and two pulp duplicates. For exploration drilling, each batch of 35 samples submitted for sample preparation and analysis includes 30 regular samples, one CRM sample, one coarse blank sample, one field duplicate sample (second half of a split core sample for HQ or NQ core size), one coarse duplicate, and one pulp duplicates. Field duplicates are inserted directly following the original sample, coarse blank material samples are inserted following a mineralized zone, and CRM samples are inserted randomly.

 

All QA/QC sample insertions maintain consecutive numerical order. Pulp reject duplicates, an additional split of material taken after the pulverizing stage, are saved and then resubmitted to the secondary laboratory at a later date at a rate of approximately 2% of the total samples submitted.

 

Each batch of check samples (pulp rejects) submitted to the secondary laboratory includes one CRM sample.

 

QA/QC samples represent approximately 20% of the total samples. A QA/QC report is prepared monthly, by the onsite Database Administrator, and reviewed by the Resource Geologist and the Nexa corporate QA/QC coordinator in San Paulo. Batches of samples identified by a QA/QC review as an anomalous result are repeated by the laboratory at the request of the Geology team. Table 8-6 shows the control sample insertion rate and the acceptance criteria followed during Nexa’s QA/QC program for Cerro Lindo.

 

Table 8-6:           Control Sample Insertion Rate and Failure Criteria 

Nexa Resources S.A. – Cerro Lindo Mine

 

Control Sample   Type   Insertion
Rate
  Failure
Criteria
  Expected/allowed
% Failures
Blanks       1 in 20 (5%)   5 x DL   <5%
CRMs       1 in 20 (5%)   Outside 3 STD   <10%
Duplicates   Twin   1 in 100 (1%)   <±30% relative error   <10%
    Coarse   1 in 100 (1%)   <±20% relative error   <10%
    Pulp   1 in 20 (5%)   <±10% relative error   <10%
External checks   Pulp   1 in 20 (5%)   <5% bias   <10%

 

A QA/QC relational database is maintained in Fusion. A summary of QA/QC submittals from 2017 to 2020 is presented in Table 8-7.

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

Technical Report Summary - January 29, 2021

 

            
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Table 8-7:            Summary of QA/QC Submittals from 2017 to 2020 

Nexa Resources S.A. – Cerro Lindo Mine

 

        2017-Aug.18   Set.18 - Abr.19   May.19 - Mar.20
Sample Type       Count   Insertion Rate   Count   Insertion Rate   Count   Insertion Rate
Regular Samples       34,963       46,420       71,546    
Blanks   Coarse   1,214   3.5%   1,794   3.9%   2,624   3.7%
CRMs   Low grade   621   1.8%   761   1.6%   859   1.2%
  Medium grade   -   -   306   0.7%   832   1.2%
  High grade   598   1.7%   656   1.4%   823   1.2%
Field Duplicates   Twin Samples   1,221   3.5%   1,234   2.7%   1,695   2.4%
  Coarse   1,212   3.5%   2,069   4.5%   3,017   4.2%
  Pulp   1,208   3.5%   1,843   4.0%   2,684   3.8%
External Check       569   1.5%   572   1.2%   -   -
            19.0%       19.9%       17.5%

 

The SLR QP has reviewed the raw data provided by Nexa, as well as annual QA/QC reports prepared by Nexa for 2017 through February 2020, and is of the opinion that the procedures meet industry standards and the conclusions of the analysis support the Mineral Resource database at the Mine.

 

8.5.3.2 Certified Reference Material

 

The regular submission of CRMs, prepared in-house and certified by accredited laboratories, for analysis help identify issues with specific sample batches and long term biases associated with the assay laboratories. CRMs were inserted into the sample stream by technicians trained in quality control procedures. Four CRMs using in-house material (MCL 04, MCL 05, MCL 06, and MCL 07) were prepared by Target Rocks Peru S.A.C. and certified by Smee & Associates Consulting Ltd. and three CRMs (PECLSTD001, PECLSTD002, PECLSTD003) were prepared and certified by Target Rocks Peru S.A.C.

 

Table 8-8 lists the certified values of the CRMs for Zn, Cu, Pb, and Ag and Table 8-9 summarizes Nexa’s in-house CRM performance.

 

The conventional approach to setting reference standard acceptance limits is to use the mean assay ±2 standard deviations as a warning limit and ±3 standard deviations as a failure limit. Figure 8-3 and Figure 8-4 show examples of zinc and copper CRM results from the Mine and Certimin laboratories for 2017-2018. Figure 8-5 illustrates the zinc and copper CRM results from the Mine for the 2018-2020 period.

 

SLR reviewed the results returned from the CRMs and offers the following comments:

 

Results for the CRMs are generally within acceptable limits with a small percentage of failures.

 

Some biases are observed in some CRMs as described below.

 

o Zinc: The control charts show a small negative zinc bias (-3% to -4%) for MCL-06, MCL-07, and PECLSTD003 for the Mine Laboratory (Figure 8-6), and a small positive bias (+3%) for PECLSTD002 and PECLSTD003 for Certimin for 2018-2019 period.
 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

Technical Report Summary - January 29, 2021

 

            
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o Copper: A small positive copper bias (5%) for MCL-04 and a small negative bias (-3% to -4%) for PECLSTD003 for the Mine Laboratory.

 

o Silver: A small positive silver bias (3% to 5%) for MCL-06 for the 2017-2018 period and MCL-04 for the 2018-2019 period, and a small negative bias (-4% to -5%) for PECLSTD003 for the Mine Laboratory. A small positive bias (4%) for MCL-04 for Certimin during the 2018-2019 period.

 

o Lead: A systematic relatively small negative lead bias (-3% to -8%) for MCL-04, MCL-06, MCL-07, PECLSTD002, and PECLSTD003 for the Inspectorate Mine and Inspectorate Lima laboratories A small positive bias (3%) for MCL-07 for Certimin. During December 2019 to January 2020, the lead failure rate for the PECLSTD001, PECLSTD002, and PECLSTD003 in the ALS laboratory was high due to the four acid digestion method used in samples with high iron content, however, sample batches related to this issue are mostly outside the Cerro Lindo mineralization domains and are not material for resource estimates purpose. ALS has changed from the four acid digestion to aqua regia digestion method resulting in failure rate within acceptable limits.

 

o Overall, there is a small percentage of failures, however, the percentage of failure for lead for PECLSTD002 and PECLSTD003 exceeded the tolerance limit (20% to 36%) for the Mine Laboratory during the 2018-2019 period. For silver, the failure percent for PECLSTD002 was exactly equal to the tolerance limit for this same period.

 

o Nexa should investigate the systematic relatively small negative bias observed for the lead at Inspectorate Mine and Inspectorate Lima, and should incorporate controls to reduce failure rates observed for some lead and silver CRMs.

 

o All biases observed should continue to be monitored on an on-going basis.
 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

Technical Report Summary - January 29, 2021

 

            
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Table 8-8:            2017-2020 Cerro Lindo In-House CRM Values 

Nexa Resources S.A. – Cerro Lindo Mine

 

Certification
Laboratory
  Analytical Method   Type Standard   Element   Best Value   SD
         
Smee & Associates Consulting Ltd.   Aqua Regia Digestion
 + AAS or ICP finish
  Low grade (MCL-04)   Ag Oz/t   0.46    
      Cu %   0.36    
      Pb %   0.157    
      Zn %   1.691    
    High grade (MCL-05)   Ag Oz/t   1.74    
      Cu %   0.791    
      Pb %   1.07    
      Zn %   4.92    
  Aqua Regia Digestion
 + ICP-OES or AAS finish
  Low grade (MCL-06)   Ag g/t   30.6    
      Cu %   0.387    
      Pb %   0.416    
      Zn %   2.18    
    High grade (MCL-07)   Ag g/t   56.4    
      Cu %   0.641    
      Pb %   1.145    
      Zn %   5.4    
      Cu %   0.429   0.01
      Pb %   0.53   0.021
      Zn %   1.04   0.017
    Medium grade (PECLSTD002)   Ag g/t   51.1   1.839
      Cu %   0.738   0.019
      Pb %   0.65   0.014
      Zn %   2.35   0.05
    High grade (PECLSTD003)   Ag g/t   109   2.637
      Cu %   1.454   0.035
      Pb %   1.6   0.029
      Zn %   5.19   0.151

   

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

Technical Report Summary - January 29, 2021

 

            
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Table 8-9:            2017-2020 Cerro Lindo In-House CRM Performance 

Nexa Resources S.A. – Cerro Lindo Mine

 

Period   Laboratory   Analytical Method   Type
Standard
  Element   No.
Samples
  Best
Value
  Mean   Bias   No.
Samples

outside
3SD
  Failure
 Rate
                   
Oct. 2017- Aug 2018   Inspectorate Mine   AAS   Low grade (MCL-04)   Ag Oz/t   20   0.46   0.47   1%   0   0%
        Cu %   20   0.36   0.38   5%   0   0%
        Pb %   20   0.16   0.14   -8%   0   0%
        Zn %   20   1.69   1.70   0%   0   0%
      High grade (MCL-05)   Ag Oz/t   19   1.74   1.74   0%   0   0%
        Cu %   19   0.79   0.80   1%   1   5%
        Pb %   19   1.07   1.06   -1%   0   0%
        Zn %   19   4.92   4.91   0%   0   0%
      Low grade (MCL-06)   Ag g/t   457   30.60   31.73   5%   0   0%
        Cu %   457   0.39   0.40   2%   0   0%
        Pb %   457   0.42   0.39   -5%   2   0%
        Zn %   457   2.18   2.11   -3%   8   2%
      High grade (MCL-07)   Ag g/t   444   56.40   57.54   2%   11   2%
        Cu %   444   0.64   0.64   0%   5   1%
        Pb %   444   1.15   1.11   -3%   12   3%
        Zn %   444   5.40   5.21   -3%   8   2%
  Certimin   ICP-OES + AAS finish   Low grade (MCL-06)   Ag g/t   312   30.60   0.99   0%   1   0%
        Cu %   312   0.39   0.39   2%   21   7%
        Pb %   312   0.42   0.41   -1%   14   4%
        Zn %   312   2.18   2.18   0%   2   1%
      High grade (MCL-07)   Ag g/t   270   56.40   1.85   2%   7   3%
        Cu %   270   0.64   0.65   1%   2   1%
        Pb %   270   1.15   1.17   3%   0   0%
        Zn %   270   5.40   5.43   1%   3   1%
 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

Technical Report Summary - January 29, 2021

 

            
  8-15   

 

Period   Laboratory   Analytical Method   Type
Standard
  Element   No.
Samples
  Best
Value
  Mean   Bias   No.
Samples

outside
3SD
  Failure
 Rate
Sep. 2018 - Apr.2019   Inspectorate Mine   AAS   Low grade (MCL-04)   Ag Oz/t   319   0.46   0.47   3%   0   0%
        Cu %   319   0.36   0.37   2%   0   0%
        Pb %   319   0.16   0.14   -8%   0   0%
        Zn %   319   1.69   1.70   0%   0   0%
      High grade (MCL-05)   Ag Oz/t   254   1.74   1.75   1%   0   0%
        Cu %   254   0.79   0.79   0%   0   0%
        Pb %   254   1.07   1.05   -2%   0   0%
        Zn %   254   4.92   4.92   0%   0   0%
      Low grade (PECLSTD001)   Ag g/t   224   42.50   42.70   0%   0   0%
        Cu %   224   0.43   0.43   0%   5   2%
        Pb %   224   0.53   0.51   -2%   2   1%
        Zn %   224   1.04   1.06   1%   9   4%
      Medium grade (PECLSTD002)   Ag g/t   223   51.10   51.71   1%   0   0%
        Cu %   223   0.74   0.74   0%   0   0%
        Pb %   223   0.65   0.62   -5%   45   20%
        Zn %   223   2.35   2.38   1%   2   1%
      High grade (PECLSTD003)   Ag g/t   200   109.00   103.57   -5%   20   10%
        Cu %   200   1.45   1.40   -4%   2   1%
        Pb %   200   1.60   1.49   -7%   71   36%
        Zn %   200   5.19   5.02   -4%   0   0%
  Certimin   ICP-OES + AAS finish   Low grade (MCL-04)   Ag Oz/t   132   0.46   0.48   4%   0   0%
        Cu %   132   0.36   0.36   -1%   0   0%
        Pb %   132   0.16   0.15   -2%   0   0%
        Zn %   132   1.69   1.66   -2%   0   0%
      High grade (MCL-05)   Ag Oz/t   127   1.74   1.75   1%   0   0%
        Cu %   127   0.79   0.81   2%   0   0%
        Pb %   127   1.07   1.09   2%   0   0%
        Zn %   127   4.92   4.93   0%   0   0%
      Low grade (PECLSTD001)   Ag g/t   86   42.50   42.69   0%   0   0%
        Cu %   86   0.43   0.44   2%   0   0%
        Pb %   86   0.53   0.53   0%   0   0%
        Zn %   86   1.04   1.05   1%   0   0%
      Medium grade (PECLSTD002)   Ag g/t   83   51.10   51.31   0%   0   0%
        Cu %   83   0.74   0.75   2%   0   0%
        Pb %   83   0.65   0.66   0%   0   0%
        Zn %   83   2.35   2.43   3%   0   0%
      High grade (PECLSTD003)   Ag g/t   75   109.00   108.76   0%   0   0%
        Cu %   75   1.45   1.48   2%   0   0%
        Pb %   75   1.60   1.61   1%   0   0%
        Zn %   75   5.19   5.33   3%   0   0%
 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

Technical Report Summary - January 29, 2021

 

            
  8-16   

 

Period   Laboratory   Analytical Method   Type
Standard
  Element   No.
Samples
  Best
Value
  Mean   Bias   No.
Samples

outside
3SD
  Failure
 Rate
May 2019 -
Feb.2020
  Inspectorate Mine   AAS   Low grade (PECLSTD001)   Ag g/t   299   42.50   42.42   0%   0   0%
        Cu %   299   0.43   0.43   0%   0   0%
        Pb %   299   0.53   0.52   -2%   7   2%
        Zn %   299   1.04   1.05   1%   0   0%
      Medium grade (PECLSTD002)   Ag g/t   271   51.10   51.33   0%   4   1%
        Cu %   271   0.74   0.75   1%   7   3%
        Pb %   271   0.65   0.63   -3%   5   2%
        Zn %   271   2.35   2.38   1%   3   1%
      High grade (PECLSTD003)   Ag g/t   268   109.00   103.9   -5%   0   0%
        Cu %   268   1.45   1.41   -3%   0   0%
        Pb %   268   1.60   1.50   -7%   2   1%
        Zn %   268   5.19   5.04   -3%   3   1%
  Certimin   ICP-OES + AAS finish   Low grade (PECLSTD001)   Ag g/t   182   42.50   42.42   0%   0   0%
        Cu %   182   0.43   0.43   1%   0   0%
        Pb %   182   0.53   0.53   1%   0   0%
        Zn %   182   1.04   1.05   1%   0   0%
      Medium grade (PECLSTD002)   Ag g/t   200   51.10   51.52   1%   0   0%
        Cu %   200   0.74   0.75   2%   0   0%
        Pb %   200   0.65   0.66   1%   0   0%
        Zn %   200   2.35   2.43   3%   1   1%
      High grade (PECLSTD003)   Ag g/t   187   109.00   108.91   0%   0   0%
        Cu %   187   1.45   1.50   3%   5   3%
        Pb %   187   1.60   1.61   1%   0   0%
        Zn %   187   5.19   5.33   3%   0   0%
  ALS       Low grade (PECLSTD001)   Ag g/t   88   42.50   42.84   1%   1   1%
        Cu %   88   0.43   0.43   1%   3   3%
        Pb %   32   0.53   0.52   0%   0   0%
        Zn %   88   1.04   1.05   0%   4   5%
      Medium grade (PECLSTD002)   Ag g/t   79   51.10   51.20   0%   1   1%
        Cu %   79   0.74   0.74   0%   1   1%
        Pb %   27   0.65   0.64   -1%   1   4%
        Zn %   79   2.35   2.39   2%   2   3%
      High grade (PECLSTD003)   Ag g/t   73   109.00   108.39   -1%   4   5%
        Cu %   73   1.45   1.47   1%   1   1%
        Pb %   26   1.60   1.55   -3%   0   0%
                Zn %   73   5.19   5.26   1%   0   0%
 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

Technical Report Summary - January 29, 2021

 

            
  8-17   

 

Period   Laboratory   Analytical Method   Type
Standard
  Element   No.
Samples
  Best
Value
  Mean   Bias   No. Samples
outside 3SD
  Failure
 Rate
    Inspectorate Lima       Low grade (PECLSTD001)   Ag g/t   289   42.50   42.27   -1%   1   0%
        Cu %   289   0.43   0.424   -1%   0   0%
        Pb %   289   0.53   0.51   -4%   0   0%
        Zn %   289   1.04   1.05   1%   2   0%
      Medium grade (PECLSTD002)   Ag g/t   282   51.10   51.32   0%   1   0%
        Cu %   282   0.74   0.75   1%   4   1%
        Pb %   282   0.65   0.61   -7%   3   0%
        Zn %   282   2.35   2.40   2%   5   1%
      High grade (PECLSTD003)   Ag g/t   295   109.00   105.4   -3%   2   1%
        Cu %   295   1.45   1.42   -2%   9   3%
        Pb %   295   1.60   1.51   -6%   1   0%
        Zn %   295   5.19   5.18   0%   3   1%

 

 

0 - 5% bias Excellent  
5 - 10% bias Attention  
>10% bias Reject STD Bias % = (mean average/ certified value) - 1
 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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Figure 8-3: CRM “MCL06” Results for Zinc – Mine and Certimin Laboratories – (2017-2018)

 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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Figure 8-4: CRM “MCL07” Results for Copper – Mine and Certimin Laboratories – (2017-2018)

 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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Figure 8-5: Cerro Lindo CRM Zn Performance for PECLSDT003 (2018-2020)

 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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Figure 8-6: Cerro Lindo CRM “PECLSDT003 (2018-2020)” Results for Copper – Inspectorate Mine Laboratory

 

In the SLR QP’s opinion, the CRMs cover a reasonable range of grades with respect to the overall grade population of the deposit and the bias observed in the CRMs is not material.

 

8.5.3.3 Blanks

 

The regular submission of blank material is used to assess contamination during sample preparation and to identify sample numbering errors. The coarse blank material is obtained from a nearby granodiorite pit that have grades that are less than the detection limits.

 

From December 2019 to January 2020, there was some evidence of contamination for the Mine Laboratory due to non-compliance with cleaning procedure during sample preparation at the crusher machine. Sample batches were not re-analyzed as there were no core samples remaining (BQ infill core drilling is completely sampled). The laboratory prepared a report and took corrective action to comply with the cleaning preparation procedure. After this incident, no contamination was observed. Results of the blanks are illustrated in Figure 8-7 with Nexa’s tolerance limit set at approximately five times the detection limits.

 

SLR reviewed charts prepared by Nexa plotting annual assay results of sterile (granodiorite) zinc, copper, silver, and lead grades against an error limit of five times the lower detection limit of the assay technique. Results indicate a negligible amount of sample contamination associated with samples from the Mine. SLR recommends monitoring more actively the blanks results to correct any contamination issues immediately, especially for the mine samples that do not have any core samples remaining to prepare more samples and be re-analyzed. Table 8-10 summarizes blank performance in 2017 to 2020.

 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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Table 8-10:          2017-2020 Cerro Lindo Blanks Performance 

Nexa Resources S.A. – Cerro Lindo Mine

 

Period   Laboratory   QA/QC Sample   Type   No. Samples   Failure Limit (%)   Bias (%) / Failure rate (%)
Ag   Cu   Pb   Zn
Oct. 2017- Aug 2018   Mine Laboratory   Blanks   Coarse   583   <5%   0.0%   0.0%   0.0%   0.0%
  Certimin   Blanks   Coarse- ICP   452   <5%   0.0%   1.8%   0.0%   0.2%
                                   
Sep. 2018 -
Apr.2019
  Mine Laboratory   Blanks   Coarse   1293   <5%   0.0%   0.0%   0.0%   0.0%
  Certimin   Blanks   Coarse   501   <5%   0.0%   0.0%   0.0%   0.1%
                                   
May 2019 -
Feb.2020
  Mine Laboratory   Blanks   Coarse   1805   <5%   0.1%   0.2%   0.0%   1.3%
  Certimin   Blanks   Coarse   581   <5%   0.0%   0.0%   0.0%   0.0%
  ALS   Blanks   Coarse   238   <5%   0.0%   0.0%   0.0%   0.0%

 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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Figure 8-7: 2019-2020 Cerro Lindo Blank Zn and Cu Assays – Inspectorate Mine Laboratory

 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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8.5.3.4 Field, Coarse Reject, and Pulp Duplicates

 

Duplicate samples help monitor preparation and assay precision and grade variability as a function of sample homogeneity and laboratory error. The field duplicate includes the natural variability of the original core sample, as well all levels of error including core splitting, sample size reduction in the preparation laboratory, sub-sampling of the pulverized sample, and the analytical error. Coarse reject and pulp duplicates provide a measure of the sample homogeneity at different stages of the preparation process (crushing and pulverizing).

 

SLR found that the duplicate results for zinc, copper, silver, and lead compare very well. The duplicates at Cerro Lindo for zinc, copper, silver, and lead fall inside the 10% relative hard value threshold. Pulp duplicate performance is summarized in Table 8-11 and shown in Figure 8-8.

 

SLR agrees with Nexa’s conclusion that data sets show a high level of precision at the Mine primary laboratory.

 

Table 8-11:          2017-2020 Cerro Lindo Duplicate Performance 

Nexa Resources S.A. – Cerro Lindo Mine

 

Period   Laboratory   QA/QC
Sample
  Type   No.
Samples
  Failure
Limit (%)
  Failure rate (%)
Ag   Cu   Pb   Zn
Oct. 2017 - Aug 2018   Mine Laboratory   Duplicates   Twin sample   586   <30%   3.9%   5.5%   5.1%   6.7%
      Coarse   589   <20%   0.2%   0.5%   0.0%   0.2%
      Pulps   588   <10%   0.3%   0.2%   0.3%   0.5%
  Certimin   Duplicates   Twin sample   635   <30%   6.9%   7.6%   6.1%   7.2%
      Coarse   623   <20%   0.3%   0.0%   0.0%   0.0%
      Pulps   620   <10%   3.4%   0.2%   0.3%   0.3%
Sep. 2018 -
Apr.2019
  Mine Laboratory   Duplicates   Twin sample   920   <30%   0.0%   0.2%   0.2%   1.7%
      Coarse   2,069   <20%   0.1%   0.1%   0.2%   0.2%
      Pulps   1,843   <10%   0.0%   0.2%   0.1%   0.1%
  Certimin   Duplicates   Twin sample   1,234   <30%   0.1%   0.7%   0.7%   2.2%
      Coarse   2,067   <20%   0.3%   0.4%   0.3%   0.3%
      Pulps   1,843   <10%   1.0%   0.2%   0.2%   0.2%
May 2019 - Feb.2020   Mine Laboratory   Duplicates   Twin sample   899   <30%   4.4%   5.7%   4.6%   6.0%
      Coarse   2,178   <20%   0.2%   0.2%   0.0%   0.3%
      Pulps   1,861   <10%   3.7%   2.6%   0.1%   0.2%
  Certimin   Duplicates   Twin sample   559   <30%   0.5%   0.2%   0.5%   1.1%
      Coarse   590   <20%   0.0%   0.0%   0.0%   0.0%
      Pulps   583   <10%   0.0%   0.3%   0.0%   0.0%
  ALS   Duplicates   Twin sample   237   <30%   0.4%   0.4%   0.8%   0.4%
      Coarse   249   <20%   0.0%   0.0%   0.0%   0.0%
      Pulps   240   <10%   0.0%   0.0%   0.0%   0.0%

 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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Figure 8-8: 2019-2020 Cerro Lindo Pulp Duplicates Zn and Cu Assays – Inspectorate Mine Laboratory

 

8.5.3.5 Check Assays

 

Submitting assays to a secondary laboratory helps monitor bias at the principal laboratory. Reference materials and blanks were inserted in the check assay batches.

 

Overall, the check assay results are reasonable. The results for zinc, copper, lead, and copper showed a good correlation with the secondary laboratory (Table 8-12). The check assays indicated that the primary laboratory had a low bias for copper (-4%). An example of zinc and copper assay performance for the check assays is shown in Figure 8-9.

 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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Table 8-12:          ALS Lima Versus Primary Laboratory Check Results - October, 2017 to April, 2019 

Nexa Resources S.A. – Cerro Lindo Mine

 

Period   Secondary Laboratory   Primary Laboratory   Element   No.   Bias%
            Ag ppm   400   2.1%
            Cu %   400   -3.9%
        Mine Laboratory   Pb %   400   2.5%
            Zn %   400   -3.8%
Oct. 2017 - Aug.2018           Ag ppm   498   3.0%
            Cu %   498   0.3%
        Certimin   Pb %   498   -1.7%
            Zn %   498   -2.5%
    ALS Lima                
          Ag ppm   273   -4.9%
            Cu %   352   -3.9%
        Mine Laboratory   Pb %   255   -4.4%
            Zn %   350   0.8%
Sep. 2018 - Apr.2019           Ag ppm   41   -4.0%
            Cu %   208   0.0%
        Certimin   Pb %   71   0.0%
            Zn %   222   4.6%

 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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Figure 8-9: 2018-2019 2020 Cerro Lindo Zn and Cu External Check Assays – Inspectorate Mine Laboratory

 

8.6 QA/QC Recommendations

 

SLR’s QA/QC recommendations are as follows:

 

Investigate the potential 5% negative bias for lead at Inspectorate Lima observed on the CRM results.

 

Incorporate controls to reduce failure rates observed for some lead and silver CRMs.

 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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Monitor more actively blank results to correct immediately any contamination issues, especially for the mine samples that do not have any core samples remaining to prepare more samples and be re-analyzed.

 

In the SLR QP’s opinion, the QA/QC program as designed and implemented by Cerro Lindo is adequate, and the assay results within the database are suitable for use in a Mineral Resource estimate.

 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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9.0 Data Verification

 

During the last quarter of 2017, Nexa transferred the drill database from Excel files to Fusion. Nexa performed an exhaustive number of checks to confirm the accuracy of the data migration. The SLR QP reviewed the resultant Excel summary and is of the opinion that Nexa performed the data migration with sufficient checks and documentation. Nexa has also implemented regular data verification workflows to ensure the collection of reliable data. Coordinates, core logging, surveying, and sampling are monitored by exploration, mine geologists, and verified routinely for consistency.

 

9.1 Databases

 

Mine data are stored in the Fusion database, which is located in the Mine server at Cerro Lindo. Nexa performs regular backups to a remote server in Lima and central server in Brazil. Access to the database is strictly controlled.

 

Logging and sampling data are digitally entered into the database by downloading the information from the logging tablets.

 

Collar coordinates are digitally entered by the surveyors in Excel files to a server managed by the Survey group. Every Friday, the database administrator e-mails the Survey group a special empty form, which is completed by the surveyors and then stored in the Survey group server. The completed form is returned to the database administrator in PDF format. Using internal routines, the database administrator later captures this information from the Survey group server and saves it in the mine server.

 

Assay data are captured from the Global LIMS server using custom routines, and this information is then entered into the Fusion database. The laboratory also issues *.csv and pdf-format certificates, however, only the information that is digitally captured from the server is considered to be the true record.

 

Personnel from the Geology department conduct daily quality control checks on the data entry. A first check consists of identifying duplicate sample numbers or lack of information for certain intervals. Every month, all the assay data entered in the server are compared with a compilation of individual *.csv files issued by the laboratory. Paper records are stored at a safe location at the mine.

 

The SLR QP is of the opinion that the data collection, import, and validation workflows are consistent with industry standards, and are of sufficient quality to support Mineral Reserve and Mineral Resource estimation.

 

9.2 Internal Verification

 

The updated database includes all historic data (drill holes and channels) and new drill holes completed to March 2, 2020. Prior to using this database for Mineral Resource estimation, the data was reviewed for geologic consistency and checked against the original information. The Cerro Lindo resource database is regularly maintained and validated by the database administrator using Fusion validation routines and by regularly checking the drill hole data on-screen.

 

The updated and validated database was exported from Fusion and sent to Lima, for an additional internal validation which involved cross-checks and consistency checks on approximately 5% of the data. The database was then transferred to a central master server (backup for all Nexa projects). Nexa prepared “The Informe de Validación de Base de Datos Cerro Lindo” report containing additional detail regarding data validation.

 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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9.3 External Verification 2003-2017

 

AMEC conducted five separate verification exercises from 2003 to 2017. These exercises included:

 

site visits to review and confirm findings by site geologists (2003)

 

drill core data, logging, and sampling reviews with site geologists (2003, 2013, 2016)

 

review of density measurement equipment and procedures (2003)

 

checks on 10% of the assay and geological data from drilling campaigns (2003)

 

high-level review of Milpo’s operational procedures and QC program (2013)

 

signed assay certificate spot checks (2016)

 

reviews of geological interpretation using wireframes, drilling, selected plans, and sections (2016, 2017)

 

spot collar and downhole survey record checks (2016)

 

a thorough audit of the 2010–2017 portion of the Cerro Lindo database (2017)

 

review of the integrity of downhole surveys (2017)

 

Amec (2017) generally concluded that the above aspects of the project were reasonable, acceptable, and adequate to support Mineral Resource estimation and mine planning. A few errors identified by Amec during data validation were immediately corrected by Cerro Lindo staff.

 

9.4 SLR Verification

 

During SLR’s site visit from June 4 to 7, 2019, SLR reviewed plans and sections, visited the core shack, examined drill core and mineralized exposures at the underground mine, reviewed core logging and QA/QC procedures and database management system and held discussions with Nexa personnel.

 

As part of the data verification process, SLR inspected the drill holes in section and plan view to review geological interpretation related to the drill hole and channel database and found good correlation. SLR queried the database for unique headers, unique samples, duplicate holes, overlapping intervals, blank and zero grade assays, and long sample intervals. SLR also reviewed QA/QC data collected by Nexa. SLR did not identify any significant discrepancies.

 

9.4.1 Assay Certificate Verification

 

SLR performed checks on the Cerro Lindo Mineral Resource database by converting approximately 164,000 assay certificate results spanning August 2017 to February 2020 from original PDF and Excel formats to reformatted comma delimited text (CSV) files, compiled and imported them to a database, and then compared the compiled certificate assays to the assay table in the Mineral Resource drill and sample database. The work matched approximately 135,000 sample IDs to the assay database for Zn, Cu (112k), Pb, Ag, and Fe. Results of the exercise are shown in Table 9-1. No significant errors were found. There were 260 samples for Ag where the values in the database ranged from 25 g/t Ag to 285 g/t Ag lower than the certificate assays. This is likely a result of choosing the lower value of multiple re-assays, and shows a conservative approach since all mis-matched values were lower in the Mineral Resource database. Assay certificates pre-2001 were not available, however, Nexa and RPA reviewed this data in sections and plan views. Overall, the data compared well with recent drilling. Based on SLR’s review, there is no reason to believe there is any significant issue related to this data, furthermore, Nexa is planning to drill during 2021 and 2022 in these areas to confirm assay values.

 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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Table 9-1:          SLR Assay Certificate Verification Results 

Nexa Resources S.A. – Cerro Lindo Mine

 

Element   Count Assays   Count Certificate IDs   Certificates Start   Certificates End   % of Assays in DB   SampleID Matches   Abs. Diff. Threshold   Num Outside of Threshold   Notes
ZN (%)   299,888   163,839   2017-08-12   2020-02-28   55%   134,832   1   6   All overlimit samples.
                                     
CU (%)   299,888   135,864   2017-08-12   2020-02-18   45%   112,391   0.001   0   Exercise captured less Cu samples than other elements
                                     
PB (%)   299,888   163,786   2017-08-12   2020-02-28   55%   134,811   1   1   Overlimit sample
                                     
AG (PPM)   299,888   163,786   2017-08-12   2020-02-28   55%   134,811   25   260   DH assays 25-285 g/t lower than certificates
                                     
FE (%)   299,888   163,786   2017-08-12   2020-02-28   55%   134,811   1   4   Diff 3-4% higher in drill hole

 

SLR found that the assay database is well maintained, and generally exceeds industry standards. The SLR QP is of the opinion that the assay database and database verification procedures for Cerro Lindo comply with industry standards, and are adequate for the estimation of Mineral Resources and Mineral Reserves.

 

9.4.2 Density Verification

 

SLR converted 3,553 density measurement certificates spanning 2013 to 2020 from original PDF and Excel formats to reformatted CSV text files, compiled and imported them to a database, and compared them to the density table in the Mineral Resource drill and sample database. There were 1,575 certificate ID matches out of 4,410 in the Mineral Resource database, resulting in a comparison rate of 36% spanning all years. SLR notes that there were no discrepancies between the certificate data and the Mineral Resource database. SLR considers this to be an excellent result. Spatial coverage of the density samples relative to Mineral Resources (blue) and Mineral Reserves (orange) are shown in Figure 9-1.

 

SLR found that the density database is well maintained, and generally exceeds industry standards. The SLR QP is of the opinion that the density database and verification procedures for Cerro Lindo comply with industry standards, and are adequate for the estimation of Mineral Resources and Mineral Reserves.

 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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Figure 9-1: Density Sampling Coverage Relative to Mineral Resources and Mineral Reserves

  

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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10.0 Mineral Processing and Metallurgical Testing

 

The Cerro Lindo processing plant has been in operation since 2007 and uses a conventional polymetallic flotation scheme to produce zinc, lead, and copper concentrates with silver content. The processing plant has a capacity of approximately 20,000 tpd. The concentrates are relatively clean and high grade, and in general do not contain penalizable concentrations of deleterious elements. A small penalty does result from the lead and zinc in the copper concentrate, which since 2016 has contained lead and zinc in the approximate range of 4.8% to 5.6%. Silver in the feed is mostly recovered to the copper and lead concentrates, resulting in silver credits for these two concentrates.

 

10.1 Recent Test Work

 

In 2018, Nexa began a program of test work to be used in the development of a geometallurgical model that would provide information that could be used to predict metallurgical response during future processing at Cerro Lindo. The work was conducted under the supervision of Transmin Metallurgical Consultants (Transmin) at the Certimin Laboratory (an independent laboratory with ISO 9001 certification and NTP-ISO/IEC 17025 Accreditation) in Lima, Peru. Test work included comminution (abrasion index (Ai) and Bond work index (BWi) determinations) and flotation tests. Results and interpretation of the third and final phase of the test work were reported in the report Estudio Geometalurgico Fase 3 para Unidad Minera Cerro Lindo (Transmin, 2020).

 

Individual samples were selected to represent the major lithologies identified in the block model, as well as specific areas as shown in Figure 10-1 and Figure 10-2. Forty-two samples were selected for comminution test work and 35 samples for flotation test work. The lithologies comprising the deposit are:

 

SPP - Pyritic, homogeneous, primary massive sulphide

 

SPB - Baritic homogeneous primary sulphides

 

SSM - Semi-massive sulphides

 

VM - Mineralized volcanic rock

 

Results of the comminution test work are summarized in Table 10-1. The BWi design value used in the 2017 design criteria for the expansion to 21,000 tpd (Cesel, 2017) was 12.4 kWh/t, and therefore, there should be no grinding capacity limitations when processing ore represented by these samples.

 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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Source: Transmin, 2020

 

Figure 10-1:            Sample Representation of Major Lithologies

 

 

Source: Transmin, 2020

 

Figure 10-2:           Sample Representation of Orebodies

 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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Figure 10-3: Location of Individual Samples in the Block Model

 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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Table 10-1:          Comminution Test Work Results for 2019 Geometallurgical Samples 

Nexa Resources S.A. – Cerro Lindo Mine

 

    Ai (g)   BWi (kWh/t)
Minimum   0.036   5.07
Maximum   0.63   18.0
Average   0.237   11.6
75th Percentile   0.374   12.1

 

Locked cycle flotation tests were conducted on three composites made up of the individual samples representing groups of orebodies; the composite make-up is summarized in Table 10-2. The flowsheet for the locked cycle tests is shown in Figure 10-4.

 

Table 10-2:          Flotation Composite Constituents 

Nexa Resources S.A. – Cerro Lindo Mine

 

Composite ID   Orebodies   Lithology
LDFC-01   OB2, OB2B   SPP
LDFC-02   OB5, OB5B, OB6   SPP, SSM, SPB
LDFC-03   OB9, OB13   SPB, VM, SSM

 

Source: Transmin, 2020

 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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Source: Transmin, 2020

 

Figure 10-4:        Locked Cycle Flotation Test Flowsheet

 

Results from the locked cycle tests are summarized in Table 10-3, showing the average bulk and zinc concentrate grades achieved in the last two cycles of the tests.

 

Table 10-3:        Average of Locked Cycle Test Concentrate Analyses for the Last Two Cycles

 

Nexa Resources S.A. – Cerro Lindo Mine

 

Sample ID Stream   Analyses
  Ag
g/t
  Cu
%
  Pb
%
  Zn
%
  Fe
%
  S
%
  Hg
ppm
  As
%
LDFC-01 Bulk Conc   470   32.8   0.76   0.74   28.0   34.4   14   0.71
Zinc Conc   135   6.4   0.1   46.4   10.7   34.8   182   0
LDFC-02 Bulk Conc   768   19.1   12.2   2.6   28.7   32.8   10   0
Zinc Conc   35   0.5   0.1   56.8   6.4   34.0   131   0

 

Variability flotation test work was conducted by completing open cycle rougher tests to produce bulk rougher and zinc concentrates. Results are presented in Table 10-4 and Table 10-5.

 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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(GRAPHIC)  

 

Table 10-4: Bulk Rougher Concentrates from Variability Tests

Nexa Resources S.A. – Cerro Lindo Mine

 

    Bulk Concentrate Grade     Recovery
Sample ID   Ag
g/t
  Cu
%
  Pb
%
  Zn
%
    Ag
%
  Cu
%
  Pb
%
  Zn
%
LDS-01   2,369   4.19   41.5   10.7     93.9   86.2   98.2   16.0
LDS-02   1,074   4.61   35.5   13.2     86.0   82.2   96.1   23.7
LDS-03   267   1.74   7.97   5.58     71.7   79.7   84.2   17.6
LDS-04   505   1.64   5.38   3.74     80.0   68.8   86.3   6.80
LDS-05   108   10.0   0.061   0.31     31.8   65.3   17.1   14.5
LDS-06   70.5   4.87   0.033   0.26     25.4   35.4   2.91   9.04
LDS-07   212   15.3   0.020   0.68     53.8   79.8   8.42   13.4
LDS-08   206   15.4   0.041   0.56     51.3   77.1   39.6   11.9
LDS-09   252   16.8   0.015   0.45     46.2   72.0   20.7   15.5
LDS-10   47.2   5.21   0.0065   0.77     56.2   84.1   32.1   10.4
LDS-11   64.8   6.28   0.038   0.26     40.8   78.1   18.7   17.0
LDS-12   75.9   6.70   0.033   0.18     35.2   64.2   18.3   20.4
LDS-13   886   9.05   3.07   1.38     89.8   92.3   75.5   55.8
LDS-14   205   13.2   0.021   0.60     47.2   68.7   21.0   9.94
LDS-17   100   9.64   0.047   0.54     42.7   65.0   15.3   8.73
LDS-18   97.4   4.08   0.44   0.54     48.1   48.9   37.4   5.52
LDS-19   115   7.08   0.080   0.92     43.6   55.9   19.6   10.6
LDS-20   34.5   3.37   0.056   0.69     34.0   60.0   39.1   2.22
LDS-21   137   3.96   2.18   2.01     46.2   57.0   51.7   2.43
LDS-22   112   0.31   0.74   0.19     70.4   76.4   63.3   23.6
LDS-24   114   3.43   0.79   3.43     49.2   22.3   62.5   2.13
LDS-26   39.2   0.60   0.16   2.34     59.1   73.9   41.3   7.08
LDS-27   859   0.63   28.0   8.61     72.8   29.4   98.5   3.70
LDS-28   2,307   1.11   31.6   11.7     69.9   30.3   96.5   4.65
LDS-29   577   12.7   18.6   7.89     88.2   78.4   98.5   3.39
LDS-31   230   13.3   0.016   0.27     44.7   68.4   18.4   9.61
LDS-37   260   4.89   0.58   0.27     81.4   87.9   67.0   26.2
LDS-38   397   16.1   0.30   0.56     60.1   85.7   59.5   11.7
LDS-39   399   11.7   0.31   1.07     85.4   93.0   66.7   10.4

 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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    Bulk Concentrate Grade     Recovery
Sample ID   Ag
g/t
  Cu
%
  Pb
%
  Zn
%
    Ag
%
  Cu
%
  Pb
%
  Zn
%
LDS-40   338   0.49   20.5   5.97     76.4   17.7   95.7   3.02
LDS-41   358   8.82   9.65   4.49     61.0   47.3   92.8   2.71
LDS-42   204   4.84   1.26   0.18     81.3   91.3   89.3   17.5
LDS-43   593   19.6   3.34   0.89     66.2   86.4   90.1   8.25
LDS-44   301   1.48   5.23   2.42     62.9   27.3   84.5   2.19
LDS-45   400   0.23   12.8   1.99     85.1   19.5   94.9   2.09

 

Source: Transmin, 2020

 

Table 10-5: Zinc Rougher Concentrates from Variability Tests

Nexa Resources S.A. – Cerro Lindo Mine

 

    Zinc Concentrate Grade     Recovery
Sample ID   Ag
g/t
  Cu
%
  Pb
%
  Zn
%
    Ag
%
  Cu
%
  Pb
%
  Zn
%
LDS-01   46.6   0.23   0.23   27.4     3.78   9.52   1.12   83.2
LDS-02   42.0   0.51   0.36   41.4     3.43   9.21   1.00   75.6
LDS-03   30.4   0.20   0.36   29.4     7.02   8.07   3.28   79.7
LDS-04   28.9   0.17   0.11   35.3     6.18   9.90   2.43   86.7
LDS-05   218   8.34   0.11   4.33     16.1   13.7   7.77   50.0
LDS-06   84.9   8.54   0.037   2.63     21.3   43.2   2.25   62.7
LDS-07   128   3.86   0.014   8.97     13.3   8.31   2.44   72.5
LDS-08   123   3.59   0.031   9.62     10.3   6.04   10.0   68.8
LDS-09   152   5.14   0.018   4.83     9.61   7.63   8.66   57.2
LDS-10   62.7   2.60   0.0090   30.3     15.7   8.82   9.39   85.6
LDS-11   103   4.09   0.065   4.26     13.1   10.2   6.52   55.3
LDS-12   75.1   4.72   0.045   0.90     15.8   20.4   11.4   44.7
LDS-13   58.1   0.45   0.31   0.56     3.84   3.03   5.01   14.9
LDS-14   106   4.31   0.019   7.46     13.9   12.7   10.8   69.4
LDS-17   70.4   4.11   0.045   9.97     14.9   13.7   7.26   79.1
LDS-18   51.8   3.74   0.17   13.4     15.9   27.9   8.73   86.0
LDS-19   54.1   3.74   0.051   7.77     18.0   25.9   10.9   78.3
LDS-20   31.4   1.38   0.032   35.3     19.4   15.4   13.9   71.2
LDS-21   25.9   0.68   0.30   40.4     11.9   13.3   9.63   66.4

 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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    Zinc Concentrate Grade     Recovery
Sample ID   Ag
g/t
  Cu
%
  Pb
%
  Zn
%
    Ag
%
  Cu
%
  Pb
%
  Zn
%
LDS-22   31.7   0.075   0.20   1.42     7.42   6.98   6.37   67.5
LDS-24   21.4   2.70   0.021   38.3     37.7   71.6   6.74   96.9
LDS-26   12.6   0.13   0.033   38.0     15.1   12.3   6.79   91.1
LDS-27   76.7   0.29   0.080   56.0     25.9   54.0   1.12   95.9
LDS-28   198   0.49   0.16   53.2     26.8   60.0   2.16   94.9
LDS-29   16.2   0.78   0.050   54.5     10.2   19.8   1.08   96.1
LDS-31   260   7.70   0.032   5.88     17.0   13.3   12.6   69.9
LDS-37   45.8   0.78   0.10   1.23     7.56   7.36   6.12   62.9
LDS-38   276   4.41   0.12   13.6     11.3   6.35   6.32   77.1
LDS-39   19.7   0.24   0.016   4.62     8.11   3.65   6.47   86.0
LDS-40   19.4   0.45   0.16   50.3     16.5   61.3   2.80   95.9
LDS-41   33.4   1.88   0.11   45.3     20.0   35.4   3.79   95.8
LDS-42   132   1.73   0.28   6.48     6.20   3.85   2.37   75.7
LDS-43   182   2.89   0.18   21.2     9.07   5.68   2.21   87.8
LDS-44   38.1   1.27   0.088   44.8     18.6   54.5   3.35   94.8
LDS-45   20.9   0.32   0.20   49.5     8.30   50.8   2.74   96.5

 

Source: Transmin, 2020

 

Transmin used the test work results to derive relationships for throughput, grinding media consumption, recovery, and concentrate grade that could be used in a geometallurgical model.

 

Key conclusions derived from the test work included the following:

 

Abrasiveness and hardness are related to lithology with the VM material being the hardest and most abrasive.

Additional comminution test work should be carried out to characterize VM material.

Zinc recovery depends on zinc head grade and the presence of soluble copper.

Higher levels of soluble copper in the feed may negatively affect the recovery of zinc and copper.

Arsenic concentration in the bulk concentrate from OB2 and OB2B material was affected by the presence of tennantite and was 0.7%.

Zinc concentrates contained mercury between 100 ppm and 300 ppm.

 

10.2 LOM Plan

 

The current LOM plan continues to 2029, with a peak processing rate of approximately 21,000 tpd. Table 10-6 presents historical and forecast processing rates, head grades, and recoveries for the LOM. Analysis of historical production demonstrates that recoveries of copper, lead, and zinc are related to their head grades, while silver recoveries to the copper and lead concentrates tend to follow the copper and lead head grades. Average LOM planned head grades of copper, lead, and silver for the next three years are similar to those experienced from 2016 to 2020 at 0.48%, 0.25%, and 0.70 oz/t, respectively, while the planned head grades of zinc decrease steadily after 2020. Head grades towards the end of the LOM are anticipated to decrease, particularly those of zinc. Forecast recoveries and concentrate grades are initially in line with those of recent years, and then are predicted to fall as head grades decrease. Apart from decreasing head grades, no fundamental changes to the concentrator feed are anticipated, and in the SLR QP’s opinion, based on recent processing plant performance, the forecast recoveries and concentrate qualities for the near future are reasonable. With end of LOM zinc and lead head grades being well below the historical ranges, however, there is a risk that actual recoveries may be lower than forecasted due to the lack of data on processing material with these low head grades.

 

 
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Production in 2020 was significantly lower than in 2019 due to the effects of the COVID-19 pandemic and associated production interruptions. On March 15, 2020, the Peruvian Government declared a national emergency and imposed operating business restrictions including on the mining sector. The quarantine period was initially expected to last until the end of March but was subsequently extended up to May 10, 2020. In light of the government restrictions, Nexa suspended production at Cerro Lindo. During this period, mining activities were limited to critical operations with a minimum workforce to ensure appropriate maintenance, safety, and security. On May 6, the Peruvian Government announced the conditions for the resumption of operations for different sectors, including mining operations above 5,000 tpd. Cerro Lindo operations, which were suspended on March 18, restarted production on May 11, 2020, following the end of the quarantine period. After the resumption of operations, Cerro Lindo ramped up production to pre-pandemic levels by June 2020.

 

A small amount of transition or supergene ore has been identified in two stopes. Large quantities of this ore fed to the concentrator could negatively affect recoveries and concentrate quality. Currently, this supergene material does not form part of the feed blend, and test work is underway to determine economical alternatives for processing the ore, e.g., by campaigning the supergene material through the processing plant using conditions and reagents optimized specifically for this material.

 

Process control and metallurgical accounting samples are collected automatically by cross stream (grinding mill feed) and in-line pipe samplers (slurry samples), and the samples are analyzed on site by a third-party laboratory operator, Bureau Veritas. Filtered concentrate is also sampled during truck loading by taking samples from the front-end loader bucket using a pipe sampler according to a pre-determined pattern. Duplicate samples are regularly sent to the laboratory operator’s Lima laboratory for analysis and comparison with the Cerro Lindo laboratory. Concentrator feed mass is measured by belt weigh scales on the two mill feed belts, and concentrates are weighed by truck scale on despatch from site. Tails mass is calculated as the difference.

 

Nexa used historical performance to estimate future recoveries and concentrate grades. In the SLR QP’s opinion, this is a common and reasonable approach, and is an adequate method of predicting future performance.

 

In the SLR QP’s opinion the metallurgical testwork is adequate for the estimation of Mineral Resources and Mineral Reserves.

 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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Table 10-6: Summary of Historical Performance and LOM Plan

Nexa Resources S.A. – Cerro Lindo Mine

 

 

 

 

Units

Actual LOM Plan

2016

2017

2018

2019

2020

2021

2022

2023

2024

2025

2026

2027

2028

2029

Plant Throughput t 7,345,202 7,297,624 6,914,653 6,799,747 5,482,211 7,000,001 7,000,000 6,500,000 6,500,000 5,000,000 5,000,001 5,000,000 5,000,000 5,101,213
tpd 20,069 19,993 18,944 18,629 17,628 19,800 19,800 18,400 18,400 14,100 14,100 14,100 14,400  
                               
Head Grades Ag oz/t 0.73 0.69 0.69 0.69 0.78 0.61 0.71 0.78 0.74 0.90 0.61 0.56 0.63 0.57
Pb % 0.29 0.27 0.25 0.25 0.29 0.23 0.25 0.26 0.22 0.28 0.18 0.13 0.13 0.10
Cu % 0.66 0.69 0.64 0.64 0.59 0.44 0.48 0.52 0.59 0.75 0.68 0.73 0.73 0.75
Zn % 2.57 2.33 2.07 2.05 1.93 1.77 1.56 1.50 1.38 1.70 1.51 1.34 1.12 0.87
Cu Concentrate t 154,362 166,595 145,685 144,568 107,283 142,861 156,213 146,070 145,387 73,479 82,194 86,950 95,163  
Pb Concentrate t 24,526 22,792 19,929 19,147 17,880 22,481 19,871 15,699 11,978 5,450 7,208 7,543 4,492  
Zn Concentrate t 295,082 264,377 221,001 216,823 165,179 175,498 146,757 144,886 146,757 70,332 71,274 72,330 72,795  
                                 

Cu Concentrate

 

Recovery                            
Cu % 84.1 86.1 86.7 86.8 85.7 85.9 86.8 86.1 86.1 84.7 85.9 86.5 87.6  
Ag % 37.4 41.6 42.6 40.4 39.1 39.9 39.9 39.9 39.9 39.9 39.9 39.9 39.9  
Grade                            
Cu % 26.3 26.2 26.3 26.1 26.0 25.9 25.9 25.9 25.9 25.9 25.9% 25.9 25.9  
Ag oz/t 12.6 12.5 13.7 13.0 13.77 14.65 14.36 14.23 12.13 12.26 12.38 12.29 10.38  
Zn % 4.3 4.1 3.6 3.7                    
Pb % 1.3 1.1 1.2 1.3                    

 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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Units

Actual LOM Plan

2016

2017

2018

2019

2020

2021

2022

2023

2024

2025

2026

2027

2028

2029

Pb Concentrate Recovery                            
Pb % 74.3 76.0 73.8 73.3 74.1 73.8 72.0 68.6 64.9 61.9 65.5 66.1 59.9  
Ag % 31.6 30.1 28.8 29.4 32.1 28.9 28.9 28.9 28.9 28.9 28.9 28.9 28.9  
Grade                            
Pb % 64.6 65.1 64.0 64.0 65.0 63.8 63.8 63.8 63.8 63.8 63.8 63.8 63.8  
Ag oz/t 67.1 64.5 67.6 71.5 66.79 67.53 81.85 95.98 106.74 119.84 102.41 102.69 159.42  
Zn Concentrate Recovery                            
Zn % 92.2 91.5 90.9 90.5 90.2 88.9 87.7 87.6 87.7 86.5 86.5 86.6 86.8  
Grade                            
Zn % 58.9 59.0 59.0 58.3 57.8 58.9 58.9 58.9 58.9 58.9 58.9 58.9 58.9  

 

Source: Nexa, 2021

 

 
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11.0 Mineral Resource Estimates

 

11.1 Summary

 

The Mineral Resource estimate for the Cerro Lindo Mine, as of December 31, 2020, using all data available as of March 2, 2020 was completed by Cerro Lindo staff (Nexa, 2020d) and reviewed by SLR.

 

The Mineral Resource estimate was completed using Datamine Studio RM and Leapfrog Geo software. Wireframes for geology and mineralization were constructed in Leapfrog Geo based on geology sections, assay results, lithological information, underground mapping, and structural data. Assays were capped to various levels based on exploratory data analysis and then composited to 2.5 m lengths. Wireframes were filled with blocks and sub-celling at wireframe boundaries. Blocks were interpolated with grade using ordinary kriging (OK) and inverse distance cubed (ID3) interpolation algorithms. Block estimates were validated using industry standard validation techniques. Classification of blocks used distance-based and other criteria. The Mineral Resource estimate was reported using all the material within resource shapes generated in Deswik Stope Optimizer (DSO) software, satisfying minimum mining size, continuity criteria, and using a net smelter return (NSR) cut-off value of US$33.56/t for sub-level stoping (SLS) resource shapes and US$49.90/t for cut and fill (C&F) resource shapes.

 

A summary of the Cerro Lindo underground Mineral Resources, exclusive of Mineral Reserves, for the Cerro Lindo deposit, is shown in Table 11-1. Table 11-2 shows the Mineral Resources sub-divided into mineralization domains. NSR cut-off values for the Mineral Resources were established using a zinc price of US$1.30/lb, a lead price of US$1.02/lb, a copper price of US$3.37/lb, and a silver price of US$19.38/oz.

 

Mineral Resources have been classified in accordance with the definitions for Mineral Resources in S-K 1300, which are consistent with Canadian Institute of Mining, Metallurgy and Petroleum (CIM) Definition Standards for Mineral Resources and Mineral Reserves (CIM (2014) definitions).

 

Table 11-1: Summary of Mineral Resources – December 31, 2020

Nexa Resources S.A. – Cerro Lindo Mine

 

Category 

Tonnage
(Mt)

 Grade Contained Metal
Zinc Lead Copper Silver Zinc Lead Copper Silver

(%)

(%)

(%)

(g/t)

(000 t)

(000 t)

(000 t)

(000 oz)

Measured 4.40 2.00 0.20 0.67 19.61 87.80 8.86 29.38 2,774.11
Indicated 3.46 1.37 0.25 0.45 24.96 47.32 8.79 15.54 2,775.90
Total M+I 7.86 1.72 0.22 0.57 21.96 135.12 17.65 44.92 5,550.01
                   
Inferred 8.71 1.28 0.35 0.33 31.23 111.12 30.59 29.10 8,747.99

 

Notes

 

1. The definitions for Mineral Resources in S-K 1300 were followed for Mineral Resources which are consistent with CIM (2014) definitions.

2. Mineral Resources are reported on a 100% ownership basis. Nexa owns 80.16%.

3. Mineral Resources are estimated at a net smelter return (NSR) cut-off value of US$33.56/t for SLS and US$49.90/t for C&F.

 

 
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4. Mineral Resources are estimated using average long term metal prices of Zn: US$2,869.14/t (US$1.30/lb), Pb: US$2,249.40/t (US$1.02/lb), Cu: 7,426.59/t (US$3.37/lb), and Ag: US$19.38/oz, and metallurgical recoveries are based on recovery curves derived from historical processing data.

5. A minimum mining width of 5.0 m and 4.0 m was used to create SLS and C&F resource shapes respectively.

6. Bulk density varies depending on mineralization domain.

7. Mineral Resources are exclusive of Mineral Reserves.

8. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability.

9. Numbers may not add due to rounding.

 

Table 11-2: Mineral Resource Estimate by Mineralization Domains – December 31, 2020

Nexa Resources S.A. – Cerro Lindo Mine

 

Category

Domain

Tonnage
(Mt)

Grade Contained Metal

Zinc
(%)

Lead (%)

Copper (%)

Silver (g/t)

Zinc (000 t)

Lead (000 t)

Copper (000 t)

Silver (000 oz)

Measured SPB 1.71 4.01 0.39 0.56 21.33 68.64 6.65 9.55 1,173.06
  SPP 2.65 0.71 0.08 0.75 18.45 18.84 2.13 19.77 1,573.10
  SSM 0.02 0.63 0.19 0.17 18.37 0.15 0.05 0.04 14.13
  VM 0.01 1.30 0.25 0.17 31.04 0.18 0.04 0.02 13.83
Indicated SPB 0.82 2.94 0.40 0.47 26.14 24.03 3.31 3.82 687.63
  SPP 1.46 0.69 0.08 0.59 15.58 10.03 1.12 8.65 731.87
  SSM 0.79 1.13 0.34 0.30 29.66 8.99 2.72 2.35 756.81
  VM 0.39 1.10 0.42 0.19 48.32 4.26 1.64 0.72 599.59
Total M&I SPB 2.53 3.66 0.39 0.53 22.89 92.66 9.96 13.37 1,860.68
  SPP 4.11 0.70 0.08 0.69 17.43 28.87 3.24 28.42 2,304.97
  SSM 0.82 1.12 0.34 0.29 29.33 9.15 2.77 2.39 770.94
  VM 0.40 1.11 0.42 0.19 47.72 4.45 1.67 0.75 613.42
Inferred SLB 0.14 0.05 0.28 0.06 24.75 0.07 0.40 0.08 112.38
  SOB 0.66 0.70 0.14 0.99 18.18 4.59 0.90 6.52 384.06
  SOP 0.15 0.22 0.03 0.52 11.77 0.33 0.05 0.78 56.76
  SPB 0.26 3.54 0.55 0.35 30.62 9.12 1.43 0.91 253.64
  SPP 0.73 0.62 0.04 0.62 11.79 4.51 0.30 4.54 277.70
  SSM 2.76 1.38 0.33 0.34 31.19 38.02 9.21 9.35 2,770.44
  V 0.12 0.51 0.24 0.22 26.28 0.61 0.29 0.26 101.68
  VM 3.89 1.38 0.46 0.17 38.31 53.88 18.02 6.66 4,791.33

 

Notes

 

1. The definitions for Mineral Resources in S-K 1300 were followed for Mineral Resources which are consistent with CIM (2014) definitions.

2. Mineral Resources are reported on a 100% ownership basis. Nexa owns 80.16%.

3. Mineral Resources are estimated at a net smelter return (NSR) cut-off value of US$33.56/t for SLS and US$49.90/t for C&F.

 
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4. Mineral Resources are estimated using average long term metal prices of Zn: US$2,869.14/t (US$1.30/lb), Pb: US$2,249.40/t (US$1.02/lb), Cu: 7,426.59/t (US$3.37/lb), and Ag: US$19.38/oz, and metallurgical recoveries are based on recovery curves derived from historical processing data.

5. A minimum mining width of 5.0 m and 4.0 m was used to create SLS and C&F resource shapes respectively.

6. Bulk density varies depending on mineralization domain.

7. Mineral Resources are exclusive of Mineral Reserves.

8. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability.

9. Numbers may not add due to rounding.

 

The SLR QP reviewed the Mineral Resource assumptions, input parameters, geological interpretation, and block modelling and reporting procedures, and is of the opinion that the Mineral Resource estimate is appropriate for the style of mineralization and that the block model is reasonable and acceptable to support the December 31, 2020 Mineral Resource estimate.

 

The SLR QP is of the opinion that, with consideration of the recommendations summarized in Section 1 and Section 23, any issues relating to all relevant technical and economic factors likely to influence the prospect of economic extraction can be resolved with further work.

 

11.2 Resource Database

 

Nexa maintains the entire database in Studio RM-Fusion. The resource database contains drilling information and analytical results up to March 2, 2020. Information received after this date was not used in the Mineral Resource estimate. The database comprises 4,808 drill holes for a total of 654,130 m and 1,040 underground channels for a total of 20,682 m.

 

The Mineral Resource estimate is based on the WGS-84 coordinate system, and two B-Level National Grid points are used as a reference for all topographical measurements.

 

SLR received data from Nexa in Microsoft Excel format. A Datamine database was also provided and extracted in CSV format. Data were amalgamated, parsed as required, and imported by SLR into Maptek’s Vulcan Version 10.1.5 (Vulcan) software and Sequent Limited’s Leapfrog software version 5.0 (Leapfrog) for review.

 

The drill hole and channel database comprise coordinate, length, azimuth, dip, lithology, density, and assay data. For grade estimation, unsampled intervals within mineralization wireframes were replaced with zero grades. Detection limit text values (e.g., “<0.05”) were replaced with numerical values that were half of the analytical detection limit. The channel sample data was converted into drill hole data for use in interpretation and Mineral Resource estimation.

 

For the purpose of the Mineral Resource estimate, the drill hole data were limited to those assays located inside the mineralization wireframes. This includes 4,124 drill holes containing 146,470 samples totalling 192,894 m, and 1,026 underground channels containing 12,994 samples totalling 20,110 m. A total of 81 drill holes were excluded from the Mineral Resource database (Table 11-3) as they either were drilled for geotechnical or geometallurgical purposes, or had missing assay values outside the mineralization zones; however, all drill holes were used for geological modelling purposes. The 29 DTH holes completed during 1995 were also excluded from the modelling and estimation processes as the historical information was not available to Nexa.

 

 
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Figure 11-1 illustrates the drill hole location in relation with the mineralization solid.

 

The SLR QP conducted a number of checks on the Mineral Resource database as discussed in Section 9, Data Verification. The SLR QP is of the opinion that the database is of high quality and generally exceeds industry standards and is appropriate to support Mineral Resource estimation.

 

Table 11-3: Excluded Holes

Nexa Resources S.A. – Cerro Lindo Mine

 

Comments

Total Metres

Hole ID

Parallel re-drilled holes 448.20 PECLD03447,PECLD03452,PECLDCL-09-406, PECLDCL-09-431, PECLDCL-10-563,
PECLDCL-13-968, PECLDCL-14-1453, PECLDCL-16-1930, PECLDCL-16-2533
Geometallurgical drill holes 100.00 PECLDCL-15-1702, PECLDCL-15-1703
Services drill holes 944.11 PECLDCL-10-486, PECLDCL-10-487, PECLDCL-10-488, PECLDCL-10-489, PECLDCL-10-490, PECLDCL-10-494, PECLDCL-10-495, PECLDCL-10-549, PECLDCL-10-551, PECLDCL-10-552, PECLDCL-10-553, PECLDCL-10-555, PECLDCL-10-557, PECLDCL-10-558, PECLDCL-10-561, PECLDCL-10-562, PECLDCL-10-586, PECLDCL-10-588, PECLDCL-10-590, PECLDCL-10-599, PECLDCL-10-601, PECLDCL-10-602
Drill holes for geomechanical purpose 3,812.55 PECLDCL-07-165, PECLDCL-07-172, PECLDCL-07-194, PECLDCL-08-199, PECLDCL-08-200, PECLDCL-08-230, PECLDCL-09-297, PECLDCL-09-301, PECLDCL-09-303, PECLDCL-09-320, PECLDCL-09-323, PECLDCL-09-326, PECLDCL-09-328, PECLDCL-09-333, PECLDCL-09-334, PECLDCL-09-355, PECLDCL-09-359, PECLDCL-09-449, PECLDCL-09-453, PECLDCL-09-454, PECLDCL-09-457, PECLDCL-09-470, PECLDCL-10-528, PECLDCL-11-668, PECLDCL-11-671, PECLDCL-11-672, PECLDCL-11-674, PECLDCL-11-678, PECLDCL-11-722, PECLDCL-11-723, PECLDCL-11-727, PECLDCL-11-728, PECLDCL-11-772, PECLDCL-11-774, PECLDCL-11-776, PECLDCL-11-778, PECLDCL-11-779, PECLDCL-11-782, PECLDCL-11-787, PECLDCL-12-882, PECLDCL-14-1477, PECLDCL-12-842, PECLDCL-12-843, PECLDCL-12-884, PECLDCL-12-903, PECLDCL-12-906, PECLDCL-12-931, PECLDCL-12-932
Total 5,304.86  

 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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Figure 11-1: 3D View of Cerro Lindo Mineralized Solid and Drill holes

 

 
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11.3 Geological Interpretation

 

Nexa changed its modelling approach based on geological continuity review since 2019. Previous models were prepared by separating geological solids into individual mining operation areas (called “OB”), creating artificial mineralization islands. The updated geological wireframes are based on the geological interpretation of lithological description, mineralization type (massive sulphide, semi-massive sulphide, sulphide, oxidized, leached, and mineralized volcanic units), and a reference assay threshold for the semi-massive and mineralized volcanic units. Some drill hole intercepts below cut-off grade were included to maintain geological continuity.

 

Structural data was used to help define the orientation of the mineralization. Structural trends were interpreted in low and high temperature areas based on Knuckey ratios model. Ratios were defined as: (cu/(cu+zn))*100.

 

The overall mineralization strikes at approximately 310° azimuth, closely follows the main fault (NW), and extends over a 1,850 m strike length. It is hosted mostly in volcanic rocks and consists of 14 interpreted geological domains, with twelve mineralization domains and two barren domains (Table 11-4).

 

Table 11-4: Geological Domains

Nexa Resources S.A. – Cerro Lindo Mine

 

Geological
Domain

CLI
Code

CGEOCD

Code

Assay Threshold Criteria

Lithology

 

Fe (%)

Zn (%)

Cu (%)

Ag (g/t)

Pb (%)

Logging

Description
SPB 1 9 - - -     SPB Mineralized baritic massive sulphides (Zn rich unit)
SPP 2 6 - - -     SPP Mineralized pyritic massive sulphides (barren and Cu rich units)
SSM 3 5 >15 and>1 or >0.25     SSM Mineralized semi-massive sulphides
VM 4 28 - >=1 or >=0.25 >=30 or >=0.5 Volc. rock Mineralized felsic volcanic rocks
Enclave 5 29 - - -     Volc. rock Barren felsic volcanic - internal waste
SOP 6 7 - - -     SOP Mineralized oxidized massive sulphides
SOB 7 10 - - -     SOB Mineralized oxidized massive sulphides baritic zone
SLB 8 11 - - -     SLB Mineralized leached massive sulphide baritic zone
Dike 10 3 - - -     Dike Barren porphyry andesite dike
OB11VM 11 28 - - -     Volc. rock Mineralized felsic volcanic rocks (in OB11)
OB12VM 12 28 - - -     Volc. rock Mineralized felsic volcanic rocks (in OB12)
OB5BVM 13 28 - - -     Volc. rock Mineralized felsic volcanic rocks (in OB5B)
OB14VM 14 28 - - -     Volc. rock Mineralized felsic volcanic rocks (in OB14)
PUCVM 15 28 - - -     Volc. rock Mineralized felsic volcanic rocks (in Pucasalla area)

 

 
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11.4 Geological Modelling

 

Nexa performed geological modelling of the Cerro Lindo deposit using Leapfrog. All contact surfaces were modelled based on the drilling and channel sampling assay results, as well as the structural and lithological controls observed in underground workings and drill core logging data. Nexa adjusted the chronology sequence interaction to mimic sectional and plan interpretation. The interaction from oldest to youngest was performed as follows: VM>>SSM>>SPP>>SPB>>V(enclave), where the wall rock was the VM and the inner domain was the enclave. The model is divided into two structural areas, West (Block 1) and East (Block 2). Both areas are modelled based on mineralization and geological trends. A total of 33 trends were interpreted and modelled (Figure 11-2). Each area then was sub-divided by geological domains, using the SSM domain as the background host rock. A total of 40 interpreted sections and 17 levels with underground mapping were used to guide the modelling, and polylines were used to better control contacts where data was sparse.

 

The dikes were modelled as vein objects and grouped using the vein system tool, with no consideration of external lithologies. Extra boundary control was imposed using polylines if necessary. The modelled mineralized zones were then clipped by the dike solids and exported to Datamine software to encode the block model.

 

Figure 11-3 shows the geological model in plan view with and without dikes.

 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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Figure 11-2: Structural Trends

 

 
Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000

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Figure 11-3: Geological Model Shown with and without Dikes

 

 
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11.5 Domain Modelling

 

11.5.1 Grade Domains

 

Nexa prepared grade domain models for the SPP, SPB, SSM, and VM geological domains by creating grade shell indicator wireframes based on grade assays and structural trend surfaces. Grade threshold limits used to outline grade shells, and to define high and low grade domains, were determined by assessing probability plots and histograms to identify different populations, and by also considering spatial grade continuity. Examples of grade distributions in SPP, SPB, SSM, and VM are shown in Figure 11-4, Figure 11-5, and Figure 11-6.

 

Indicator solids were built for each element within the geological domains, based on the radial basis function (RBF) interpolants, which interpolate all samples above a defined cut-off grade. As a result, high and low grade domains were created for each element. Silver and lead used the same grade domains as they were found statistically and spatially correlated.

 

The purpose of building high grade and low grade domains was to control the internal dilution and limit the smearing of high grade values into low grade values and vice versa, during the grade estimation. Table 11-5 lists the zinc, copper, silver, and lead grade domains and Figure 11-7, Figure 11-8, Figure 11-9, Figure 11-10, Figure 11-11, and Figure 11-12 illustrate plan views of the grade domains in SPP, SPB, SSM, and VM.

 

For the SOP, SOB, SLB, OB11VM, OB12VM, OB5BVM, OB14VM, and PUCVM domains, grade domains were not built due to their small volume and poor grade continuity. Geological models in combination with grade domains were used to prepare the estimation domains

 

Table 11-5: Zn, Cu, Ag and Pb Grade Domains 

Nexa Resources S.A. – Cerro Lindo Mine

 

 

Grade Shell
Code

Grade
Domain

Grade Shell Indicator

Geological
Domain

Zinc Grade Domains SPBHZN High Grade Inside 2.5% Zn Grade Shell SPB
SPBLZN Low Grade Outside 2.5 % Zn Grade Shell
SPPHZN High Grade Inside 0.3% Zn Grade Shell SPP
SPPLZN Low Grade Outside 0.3 % Zn Grade Shell
SSMHZN High Grade Inside 0.5% Zn Grade Shell SSM
SSMLZN Low Grade Outside 0.5 % Zn Grade Shell
VMHZN High Grade Inside 0.4% Zn Grade Shell VM
VMLZN Low Grade Outside 0.4 % Zn Grade Shell
Copper Grade Domains SPBHCU High Grade Inside 0.2% Cu Grade Shell SPB
SPBLCU Low Grade Outside 0.2% Cu Grade Shell
SPPHCU High Grade Inside 0.25% Cu Grade Shell SPP
SPPLCU Low Grade Outside 0.25% Cu Grade Shell
SSMHCU High Grade Inside 0.25% Cu Grade Shell SSM
SSMLCU Low Grade Outside 0.25% Cu Grade Shell
VMHCU High Grade Inside 0.15% Cu Grade Shell VM
     
 
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Grade Shell
Code 

Grade
Domain 

Grade Shell Indicator 

Geological
Domain 

  VMLCU Low Grade Outside 0.15% Cu Grade Shell  
Silver and Lead Grade Domains SPBHAG High Grade Inside 30 g/t Ag Grade Shell SPB
SPBLAG Low Grade Outside 30 g/t Ag Grade Shell
SPPHAG High Grade Inside 9 g/t Ag Grade Shell SPP
SPPLAG Low Grade Outside 9 g/t Ag Grade Shell
SSMHAG High Grade Inside 20 g/t Ag Grade Shell SSM
SSMLAG Low Grade Outside 20 g/t Ag Grade Shell
VMHAG High Grade Inside 35 g/t Ag Grade Shell VM
VMLAG Low Grade Outside 35 g/t Ag Grade Shell

 

 
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Figure 11-4: Zn Distribution in SPB and SSM Domains

 

 
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Figure 11-5: Cu Distribution in SPB and SPP Domains

 

 
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Figure 11-6: Ag Distribution in SSM and VM Domains

 

 
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Figure 11-7: SPB and SPP High and Low Grade Zn Domains – Plan View

 

 
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Figure 11-8: SSM and VM High and Low Zn Domains – Plan View

 

 
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Figure 11-9: SPB and SPP High and Low Grade Cu Domains – Plan View

 

 
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Figure 11-10: SSM and VM High and Low Grade Cu Domains – Plan View

 

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Figure 11-11: SPB and SPP High and Low Grade AG-Pb Domains – Plan View

 

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Figure 11-12: SSM and VM High and Low Grade Ag-Pb Domains – Plan View

 

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11.5.2 Estimation Domains

 

Based on observations of the drill core and underground mineralization exposures, discussions with the geologists on site, a review of the data in 3D, and statistical analysis, the mineralization at Cerro Lindo is considered to be lithologically and structurally controlled. The bulk of the mineralization is located in the SPP and SPB domains, with some mineralization in the SSM domain, and lesser mineralization in the VM, SOB, SOP, SLB, OB11VM, OB12VM, OB5BVM, OB14VM, and PUCVM domains. High grade zones usually present more massive mineralization, with higher grade Zn and Cu zones.

 

Nexa created 33 estimation domains using a number of geological parameters, which include: geological domains (lithological control and mineralization type), grade domains (high grade and low grade domains), and the anisotropy and orientation of the estimation domains. Table 11-6 summarizes the estimation domains.

 

Table 11-6:         Estimation Domains 

Nexa Resources S.A. – Cerro Lindo Mine

 

Estimation Domain   Geological Domain   CLI   GEOCD   Grade Shell
Code
  C_Shell
Mineralized baritic massive sulphides High Grade Domain Zn   SPB   1   9   SPBHZN   101
Mineralized baritic massive sulphides Low Grade Domain Zn   SPB   1   9   SPBLZN   1
Mineralized baritic massive sulphides High Grade Domain Cu   SPB   1   9   SPBLCU   201
Mineralized baritic massive sulphides Low Grade Domain Cu   SPB   1   9   SPBLCU   1
Mineralized baritic massive sulphides High Grade Domain Ag   SPB   1   9   SPBLAG   301
Mineralized baritic massive sulphides Low Grade Domain Ag   SPB   1   9   SPBLAG   1
Mineralized pyritic massive sulphides High Grade Domain Zn   SPP   2   6   SPPHZN   102
Mineralized pyritic massive sulphides Low Grade Domain Zn   SPP   2   6   SPPLZN   2
Mineralized pyritic massive sulphides High Grade Domain Cu   SPP   2   6   SPPLCU   202
Mineralized pyritic massive sulphides Low Grade Domain Cu   SPP   2   6   SPPLCU   2
Mineralized pyritic massive sulphides High Grade Domain Ag   SPP   2   6   SPPLAG   302
Mineralized pyritic massive sulphides Low Grade Domain Ag   SPP   2   6   SPPLAG   2
Mineralized semi-massive sulphides High Grade Domain Zn   SSM   3   5   SSMHZN   103

 

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Estimation Domain   Geological Domain   CLI   GEOCD   Grade Shell
Code
  C_Shell
Mineralized semi-massive sulphides Low Grade Domain Zn   SSM   3   5   SSMLZN   3
Mineralized semi-massive sulphides High Grade Domain Cu   SSM   3   5   SSMLCU   203
Mineralized semi-massive sulphides Low Grade Domain Cu   SSM   3   5   SSMLCU   3
Mineralized semi-massive sulphides High Grade Domain Ag   SSM   3   5   SSMLAG   303
Mineralized semi-massive sulphides Low Grade Domain Ag   SSM   3   5   SSMLAG   3
Mineralized volcanic rocks High Grade Domain Zn   VM   4   28   VMHZN   104
Mineralized volcanic rocks Low Grade Domain Zn   VM   4   28   VMLZN   4
Mineralized volcanic rocks High Grade Domain Cu   VM   4   28   VMLCU   204
Mineralized volcanic rocks Low Grade Domain Cu   VM   4   28   VMLCU   4
Mineralized volcanic rocks High Grade Domain Ag   VM   4   28   VMLAG   304
Mineralized volcanic rocks Low Grade Domain Ag   VM   4   28   VMLAG   4
Mineralized oxidized sulphides zone   SOP   6   7   -   -
Mineralized oxidized baritic sulphides zone   SOB   7   10   -   -
Mineralized leached zone   SLB   8   11   -   -
Mineralized volcanic rocks inside OB11   OB11VM   11   28   -   -
Mineralized volcanic rocks inside OB12   OB12VM   12   28   -   -
Mineralized volcanic rocks inside OB5B   OB5BVM   13   28   -   -
Mineralized volcanic rocks inside OB14   OB14VM   14   28   -   -
Mineralized volcanic rocks inside PUC   PUCVM   15   28   -   -

 

With respect to the geological and domain modelling used to support the Mineral Resource estimate, SLR offers the following conclusions and recommendations:

 

Overall, the mineralization wireframes are adequate for the style of mineralization.

 

The wireframes and estimation domains are suitable to support Mineral Resource and Mineral Reserve estimation.

 

Nexa significantly improved the Cerro Lindo geological model which is good representation of the geology of the deposit.

 

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Continue improving the geological model and estimation domains.

 

Model the volcanic rocks (wall rock) and use this domain as a background lithology to enhance the contact of the wall rock with the mineralized domains, and incorporate VM intervals that were not modelled. This will help generate more realistic estimation domains, and grade and density estimates.

 

Build a more detailed litho-structural model with the main lithologies/stratigraphy, dikes, faults, and folds, to better define the geometry and boundaries of the mineralization and customize local search anisotropies and directions. In cross section looking northwest, folding is observed, and in longitudinal section looking northeast, some dikes appear to behave like faults. Some mineralization domains appear to have mineralization trending in various directions due to local faulting and folding so further sub-domaining may be warranted.

 

Nexa incorporated high and low grade domains to control the mix of populations and smearing of grades across domains. SLR concurs with this approach, however, based on visual validation, the high grade continuity appears to be affected as a result of modelling the high grade domains individually for each domain. SLR recommends that Nexa not separate the grade domains by geological domains to maintain grade continuity, evaluate incorporating mineralogy data, and review the geometry and trends of the grade domains.

 

Nexa created mineralization trend surfaces based on a ratio of Cu / (Cu+Zn). These surfaces were used to create the geological domains, grade envelopes, and dynamic anisotropy (DA) angles. Overall, the surfaces follow the mineralization trends, however, the DA angle results for some areas (OB1) do not follow grade trends. This does not have a significant impact on Mineral Resource estimation as composite grades have been estimated within their respective grade domain and there is sufficient drilling to control grade interpolation. SLR recommends reviewing the DA angle results using grade trends and structural interpretations.

 

Post-mineralization dike modelling should continuous be improved to capture more of the logged intercepts and core angles, as well as contacts based on the underground mapping. Dikes are important to delimit internal waste and to guide the local interpolation strategy as some of them are controlling the mineralization trends behaving like faults.

 

Model east and west blocks as a continuous mineralization solid. This is a minor issue and was addressed in some domains.

 

11.6 Resource Assays

 

Nexa performed exploratory data analysis (EDA) for each estimation domain, including univariate statistics, histograms, cumulative probability plots; box plots to compare geology domain statistics, and contact plots to investigate grade profiles between estimation domains and determine the extent of sample sharing across the geology contacts within the rock type domains. Hard boundaries were determined for each of the estimation variables (zinc, copper, lead, and silver).

 

Table 11-7 lists composited univariate statistics for zinc, copper, lead, and silver by estimation domain. The majority of the zinc is contained in four estimation domains: SPBHZN, SPBLZN, SPPHZN, and SSMHZN. The majority of the copper is contained in three estimation domains: SPPHCU, SPBHCU, and SSMHCU.

 

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Table 11-7:         Estimation Domain Raw Assay Statistics 

Nexa Resources S.A. – Cerro Lindo Mine

 

Estimation   Geological   Grade             Uncapped values        
Domain   Domain   Domain   Grade   No. Samples   Minimum   Maximum   Mean   Variance   Std. Dev.   CV
SPBHAG       HG   Ag (g/t)   14,451   0.50   1,892.02   68.56   6,443.05   80.27   1.17
SPBLAG       LG   Ag (g/t)   27,605   0.50   1,911.00   13.78   351.37   18.74   1.36
SPBHCU       HG   Cu (%)   24,819   0.01   22.43   0.80   1.11   1.05   1.31
SPBLCU       LG   Cu (%)   17,237   0.01   11.65   0.14   0.07   0.26   1.81
SPBHFE   SPB   HG   Fe (%)   24,819   0.05   52.79   20.27   178.17   13.35   0.66
SPBLFE       LG   Fe (%)   17,237   0.05   60.00   18.25   119.07   10.91   0.60
SPBHPB       HG   Pb (%)   14,451   0.01   42.59   1.28   2.92   1.71   1.34
SPBLPB       LG   Pb (%)   27,605   0.01   23.92   0.30   0.43   0.66   2.17
SPBHZN       HG   Zn (%)   29,516   0.01   66.92   6.82   27.94   5.29   0.77
SPBLZN       LG   Zn (%)   12,540   0.01   33.97   1.52   4.29   2.07   1.36
SPPHAG       HG   Ag (g/t)   46,691   0.50   10,398.51   24.71   3,617.39   60.14   2.43
SPPLAG       LG   Ag (g/t)   22,328   0.50   528.76   4.69   42.42   6.51   1.39
SPPHCU       HG   Cu (%)   48,190   0.01   33.36   0.97   0.99   1.00   1.03
SPPLCU       LG   Cu (%)   20,829   0.01   12.14   0.11   0.02   0.14   1.33
SPPHFE   SPP   HG   Fe (%)   48,190   0.05   62.68   32.92   192.48   13.87   0.42
SPPLFE       LG   Fe (%)   20,829   0.05   54.74   32.76   177.06   13.31   0.41
SPPHPB       HG   Pb (%)   46,691   0.01   63.70   0.11   0.38   0.62   5.89
SPPLPB       LG   Pb (%)   22,328   0.01   4.95   0.02   0.01   0.10   4.59
SPPHZN       HG   Zn (%)   28,169   0.01   40.70   1.41   6.17   2.48   1.76
SPPLZN       LG   Zn (%)   40,850   0.01   29.79   0.13   0.15   0.38   2.93
SSMHAG       HG   Ag (g/t)   8,513   0.50   1,939.00   59.97   9,226.04   96.05   1.60
SSMLAG       LG   Ag (g/t)   16,865   0.50   1,042.99   8.81   267.24   16.35   1.86
SSMHCU       HG   Cu (%)   9,296   0.01   12.39   0.66   0.61   0.78   1.19
SSMLCU       LG   Cu (%)   16,082   0.01   4.42   0.10   0.02   0.13   1.37
SSMHFE   SSM   HG   Fe (%)   9,296   0.05   52.53   19.70   117.73   10.85   0.55
SSMLFE       LG   Fe (%)   16,082   0.05   49.83   19.16   107.89   10.39   0.54
SSMHPB       HG   Pb (%)   8,513   0.01   30.52   0.57   1.40   1.18   2.07
SSMLPB       LG   Pb (%)   16,865   0.01   13.84   0.07   0.05   0.23   3.35
SSMHZN       HG   Zn (%)   8,001   0.01   40.81   2.54   9.56   3.09   1.22
SSMLZN       LG   Zn (%)   17,377   0.01   30.22   0.12   0.21   0.46   3.73

 

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Estimation   Geological   Grade            Uncapped values        
Domain   Domain   Domain   Grade   No. Samples   Minimum   Maximum   Mean   Variance   Std. Dev.   CV
VMHAG       HG   Ag (g/t)   4,318   0.50   2,792.16   98.23   23,169.54   152.22   1.55
VMLAG       LG   Ag (g/t)   6,553   0.50   538.71   19.23   638.27   25.26   1.31
VMHCU       HG   Cu (%)   5,895   0.01   14.87   0.54   0.54   0.74   1.37
VMLCU       LG   Cu (%)   4,976   0.01   3.07   0.07   0.01   0.11   1.48
VMHFE   VM   HG   Fe (%)   5,895   0.05   50.61   11.62   83.50   9.14   0.79
VMLFE       LG   Fe (%)   4,976   0.05   49.41   7.81   49.02   7.00   0.90
VMHPB       HG   Pb (%)   4,318   0.01   36.60   0.88   2.54   1.59   1.81
VMLPB       LG   Pb (%)   6,553   0.01   11.46   0.18   0.16   0.39   2.15
VMHZN       HG   Zn (%)   5,982   0.01   36.14   1.98   7.38   2.72   1.37
VMLZN       LG   Zn (%)   4,889   0.01   36.86   0.22   0.72   0.85   3.94
            Ag (g/t)   9,453   0.50   2,810.51   37.00   8,665.31   93.09   2.52
            Cu (%)   9,453   0.01   15.08   0.40   0.69   0.83   2.05
V   V   -   Fe (%)   9,453   0.05   49.40   9.16   95.47   9.77   1.07
            Pb (%)   9,453   0.01   45.00   0.36   1.43   1.19   3.29
            Zn (%)   9,453   0.01   26.65   0.66   3.18   1.78   2.71
            Ag (g/t)   807   0.50   816.00   12.86   1,044.52   32.32   2.51
            Cu (%)   807   0.01   14.65   0.74   1.15   1.07   1.45
SOP   SOP   -   Fe (%)   807   0.05   50.42   27.21   315.96   17.78   0.65
            Pb (%)   807   0.01   7.10   0.06   0.07   0.27   4.82
            Zn (%)   807   0.01   18.03   0.26   0.34   0.59   2.24
            Ag (g/t)   540   0.50   335.00   25.12   799.35   28.27   1.13
            Cu (%)   540   0.01   10.32   1.37   2.08   1.44   1.05
SOB   SOB   -   Fe (%)   540   0.05   50.60   22.07   163.77   12.80   0.58
            Pb (%)   540   0.01   2.48   0.20   0.14   0.37   1.89
            Zn (%)   540   0.01   14.38   1.20   2.95   1.72   1.44
            Ag (g/t)   227   0.50   240.43   29.47   2,437.84   49.37   1.68
            Cu (%)   227   0.01   6.71   0.19   0.56   0.75   3.88
SLB   SLB   -   Fe (%)   227   0.05   40.00   3.77   94.81   9.74   2.59
            Pb (%)   227   0.01   5.02   0.46   0.91   0.96   2.07
            Zn (%)   227   0.01   5.26   0.16   0.37   0.61   3.88

 

Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
Technical Report Summary - January 29, 2021
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Estimation   Geological   Grade             Uncapped values        
Domain   Domain   Domain   Grade   No. Samples   Minimum   Maximum   Mean   Variance   Std. Dev.   CV
            Ag (g/t)   37   2.00   76.00   12.25   174.35   13.20   1.08
            Cu (%)   37   0.01   0.52   0.12   0.01   0.12   0.97
OB11VM   OB11VM   -   Fe (%)   37   3.88   20.01   8.87   10.00   3.16   0.36
            Pb (%)   37   0.01   2.66   0.17   0.11   0.33   1.91
            Zn (%)   37   0.03   41.86   4.51   97.17   9.86   2.19
            Ag (g/t)   293   0.50   436.00   32.54   2,848.00   53.37   1.64
            Cu (%)   293   0.01   3.38   0.15   0.07   0.27   1.82
OB12VM   OB12VM   -   Fe (%)   293   1.30   31.70   10.66   38.19   6.18   0.58
            Pb (%)   293   0.01   2.55   0.21   0.14   0.37   1.81
            Zn (%)   293   0.01   6.42   0.68   0.81   0.90   1.32
            Ag (g/t)   133   0.50   115.00   15.18   406.68   20.17   1.33
            Cu (%)   133   0.01   0.89   0.02   0.00   0.07   2.74
OB5BVM   OB5BVM   -   Fe (%)   133   0.05   18.15   3.32   6.63   2.58   0.78
            Pb (%)   133   0.01   2.29   0.30   0.16   0.40   1.32
            Zn (%)   133   0.01   14.88   2.48   10.05   3.17   1.28
            Ag (g/t)   562   0.50   1,705.99   50.87   17,545.37   132.46   2.60
            Cu (%)   562   0.01   1.72   0.10   0.03   0.18   1.79
OB14VM   OB14VM   -   Fe (%)   562   0.05   40.00   7.90   54.04   7.35   0.93
            Pb (%)   562   0.01   8.92   0.68   1.17   1.08   1.59
            Zn (%)   562   0.01   18.20   1.73   5.26   2.29   1.32
            Ag (g/t)   38   0.50   153.00   40.10   1,573.72   39.67   0.99
            Cu (%)   38   0.01   1.78   0.23   0.11   0.33   1.44
PUCVM   PUCVM   -   Fe (%)   38   2.89   20.70   8.14   17.60   4.20   0.52
            Pb (%)   38   0.01   6.57   0.68   1.19   1.09   1.60
            Zn (%)   38   0.03   10.94   1.11   5.52   2.35   2.12

 

11.7 Treatment of High Grade Assays

 

Where the assay distribution is skewed positively or approaches log-normal, erratic high grade values can have a disproportionate effect on the average grade of a deposit. One method of treating these outliers in order to reduce their influence on the average grade is to cut or cap them at a specific grade level.

 

Nexa applied high grade capping to Zn, Pb, Cu, Ag, and Fe assays in order to limit the influence of a small amount of outlier values located in the upper tail of the metal distributions (Figure 11-13, Figure 11-14, and Figure 11-15). Raw assays were capped prior to compositing. A summary of final capping levels is shown in Table 11-8. A summary of capped grade statistics is provided in Table 11-9.

 

Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
Technical Report Summary - January 29, 2021
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Grade plots commonly show outliers at the 98th to 99th percentile. The final outlier threshold was selected at lower percentiles to adjust the capping levels with grade reconciliation with the mine and process, and to reduce global bias.

 

Table 11-8:           Grade Capping Levels 

Nexa Resources S.A. – Cerro Lindo Mine

 

Geological
Domain
  CLI   Grade
Domain
  Zn(%)   Pb(%)   Cu(%)   Ag(g/t   Fe(%)
SPB   1   HG   25.00   7.00   4.00   300.00   45.00
      LG   8.00   4.50   1.00   100.00   45.00
SPP   2   HG   10.00   2.00   5.00   200.00   45.00
      LG   1.70   0.20   1.20   30.00   45.00
SSM   3   HG   15.00   5.00   3.50   300.00   45.00
      LG   1.50   1.50   1.10   90.00   45.00
VM   4   HG   8.00   5.00   3.00   400.00   40.00
      LG   2.00   2.00   0.50   100.00   40.00
V   5   -   2.00   1.00   1.00   100.00   40.00
SOP   6   -   1.70   0.35   2.50   80.00   40.00
SOB   7   -   5.30   0.90   4.20   78.00   45.00
SLB   8   -   0.70   2.50   0.90   130.00   40.00
OB11VM   11   -   4.50   0.50   0.35   45.00   12.00
OB12VM   12   -   1.20   0.60   0.60   150.00   25.00
OB5BVM   13   -   5.80   1.10   0.11   60.00   8.00
OB14VM   14   -   7.50   3.20   0.50   200.00   25.00
PUCVM   15   -   4.00   2.50   0.50   120.00   15.00

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Figure 11-13:          Capping Analysis for SPB Zn High Grade Mineralization

 

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Figure 11-14:           Capping Analysis for SPB Cu High Grade Mineralization

 

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Figure 11-15:           Capping Analysis for SPB Ag High Grade Mineralization

 

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Table 11-9:           Capped Assay Statistics 

Nexa Resources S.A. – Cerro Lindo Mine

 

Estimation   Geological   Grade    Grade       Capped Values
Domain   Domain   Domain   (units)   No. Samples   Minimum   Maximum   Mean   Variance   Std. Dev.   CV
SPBHAG     HG   Ag (g/t)   14,451   0.50   300.00   65.20   3,322.56   57.64   0.88
SPBLAG       LG   Ag (g/t)   27,605   0.50   100.00   13.44   168.57   12.98   0.97
SPBHCU       HG   Cu (%)   24,819   0.01   4.00   0.76   0.57   0.76   1.00
SPBLCU     LG   Cu (%)   17,237   0.01   1.00   0.13   0.02   0.15   1.15
SPBHFE   SPB   HG   Fe (%)   24,819   0.05   45.00   20.26   177.83   13.34   0.66
SPBLFE       LG   Fe (%)   17,237   0.05   45.00   18.25   118.89   10.90   0.60
SPBHPB       HG   Pb (%)   14,451   0.01   7.00   1.23   2.02   1.42   1.15
SPBLPB       LG   Pb (%)   27,605   0.01   4.50   0.30   0.35   0.60   2.00
SPBHZN       HG   Zn (%)   29,516   0.01   25.00   6.77   25.23   5.02   0.74
SPBLZN       LG   Zn (%)   12,540   0.01   8.00   1.44   2.71   1.65   1.14
SPPHAG     HG   Ag (g/t)   46,691   0.50   200.00   23.57   645.28   25.40   1.08
SPPLAG       LG   Ag (g/t)   22,328   0.50   30.00   4.54   12.49   3.53   0.78
SPPHCU       HG   Cu (%)   48,190   0.01   5.00   0.95   0.71   0.84   0.89
SPPLCU     LG   Cu (%)   20,829   0.01   1.20   0.11   0.01   0.11   1.04
SPPHFE   SPP   HG   Fe (%)   48,190   0.05   45.00   32.78   188.51   13.73   0.42
SPPLFE       LG   Fe (%)   20,829   0.05   45.00   32.62   172.92   13.15   0.40
SPPHPB       HG   Pb (%)   46,691   0.01   2.00   0.09   0.07   0.27   3.11
SPPLPB       LG   Pb (%)   22,328   0.01   0.20   0.02   0.00   0.03   1.49
SPPHZN       HG   Zn (%)   28,169   0.01   10.00   1.32   3.66   1.91   1.45
SPPLZN       LG   Zn (%)   40,850   0.01   1.70   0.12   0.02   0.14   1.15
SSMHAG     HG   Ag (g/t)   8,513   0.50   300.00   54.54   3,560.40   59.67   1.09
SSMLAG       LG   Ag (g/t)   16,865   0.50   90.00   8.51   84.91   9.21   1.08
SSMHCU       HG   Cu (%)   9,296   0.01   3.50   0.63   0.39   0.62   0.98
SSMLCU     LG   Cu (%)   16,082   0.01   1.10   0.10   0.01   0.12   1.21
SSMHFE   SSM   HG   Fe (%)   9,296   0.05   45.00   19.70   117.53   10.84   0.55
SSMLFE       LG   Fe (%)   16,082   0.05   45.00   19.16   107.81   10.38   0.54
SSMHPB       HG   Pb (%)   8,513   0.01   5.00   0.53   0.77   0.88   1.64
SSMLPB       LG   Pb (%)   16,865   0.01   1.50   0.06   0.01   0.12   1.84
SSMHZN       HG   Zn (%)   8,001   0.01   15.00   2.49   7.66   2.77   1.11
SSMLZN       LG   Zn (%)   17,377   0.01   1.50   0.11   0.04   0.19   1.83

 

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Technical Report Summary - January 29, 2021
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Estimation   Geological   Grade   Grade       Capped Values
Domain   Domain   Domain   (units)   No. Samples   Minimum   Maximum   Mean   Variance   Std. Dev.   CV
VMHAG     HG   Ag (g/t)   4,318   0.50   400.00   88.62   8,337.99   91.31   1.03
VMLAG       LG   Ag (g/t)   6,553   0.50   100.00   18.34   292.57   17.10   0.93
VMHCU       HG   Cu (%)   5,895   0.01   3.00   0.51   0.31   0.56   1.09
VMLCU     LG   Cu (%)   4,976   0.01   0.50   0.07   0.01   0.08   1.10
VMHFE    VM   HG   Fe (%)   5,895   0.05   40.00   11.60   82.39   9.08   0.78
VMLFE       LG   Fe (%)   4,976   0.05   40.00   7.79   48.02   6.93   0.89
VMHPB       HG   Pb (%)   4,318   0.01   5.00   0.80   1.14   1.07   1.34
VMLPB       LG   Pb (%)   6,553   0.01   2.00   0.17   0.07   0.27   1.55
VMHZN       HG   Zn (%)   5,982   0.01   8.00   1.80   3.29   1.81   1.00
VMLZN       LG   Zn (%)   4,889   0.01   2.00   0.17   0.10   0.31   1.79
        Ag (g/t)   9,453   0.50   100.00   25.09   949.86   30.82   1.23
            Cu (%)   9,453   0.01   1.00   0.28   0.11   0.33   1.17
V   V   -   Fe (%)   9,453   0.05   40.00   9.12   93.32   9.66   1.06
            Pb (%)   9,453   0.01   1.00   0.21   0.09   0.30   1.42
            Zn (%)   9,453   0.01   2.00   0.40   0.39   0.62   1.57
        Ag (g/t)   807   0.50   80.00   11.62   261.35   16.17   1.39
            Cu (%)   807   0.01   2.50   0.66   0.45   0.67   1.02
SOP   SOP   -   Fe (%)   807   0.05   40.00   27.02   309.86   17.60   0.65
            Pb (%)   807   0.01   0.35   0.04   0.01   0.08   2.02
            Zn (%)   807   0.01   1.70   0.24   0.14   0.38   1.58
        Ag (g/t)   540   0.50   78.00   23.51   388.91   19.72   0.84
            Cu (%)   540   0.01   4.20   1.29   1.42   1.19   0.92
SOB   SOB   -   Fe (%)   540   0.05   45.00   21.99   160.02   12.65   0.58
            Pb (%)   540   0.01   0.90   0.17   0.07   0.26   1.55
            Zn (%)   540   0.01   5.30   1.12   2.01   1.42   1.26
        Ag (g/t)   227   0.50   130.00   26.46   1,600.15   40.00   1.51
            Cu (%)   227   0.01   0.90   0.10   0.06   0.24   2.49
SLB   SLB   -   Fe (%)   227   0.05   40.00   3.77   94.81   9.74   2.59
            Pb (%)   227   0.01   2.50   0.40   0.52   0.72   1.82
            Zn (%)   227   0.01   0.70   0.07   0.03   0.17   2.55
        Ag (g/t)   37   2.00   45.00   11.69   123.39   11.11   0.95
            Cu (%)   37   0.01   0.35   0.11   0.01   0.10   0.88
OB11VM   OB11VM   -   Fe (%)   37   3.88   12.00   8.47   4.41   2.10   0.25
            Pb (%)   37   0.01   0.50   0.14   0.02   0.15   1.07
            Zn (%)   37   0.03   4.50   1.81   2.03   1.42   0.79

 

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Estimation   Geological   Grade    Grade       Capped Values
Domain   Domain   Domain   (units)   No. Samples   Minimum   Maximum   Mean   Variance   Std. Dev.   CV
        Ag (g/t)   293   0.50   150.00   29.20   1,384.82   37.21   1.27
            Cu (%)   293   0.01   0.60   0.13   0.02   0.13   1.04
OB12VM   OB12VM   -   Fe (%)   293   1.30   25.00   10.54   34.05   5.84   0.55
            Pb (%)   293   0.01   0.60   0.15   0.02   0.15   0.99
            Zn (%)   293   0.01   1.20   0.52   0.11   0.33   0.64
        Ag (g/t)   133   0.50   60.00   14.28   289.30   17.01   1.19
            Cu (%)   133   0.01   0.11   0.02   0.00   0.03   1.39
OB5BVM   OB5BVM   -   Fe (%)   133   0.05   8.00   3.18   4.60   2.15   0.67
            Pb (%)   133   0.01   1.10   0.28   0.11   0.33   1.18
            Zn (%)   133   0.01   5.80   1.98   3.21   1.79   0.91
        Ag (g/t)   562   0.50   200.00   35.17   2,706.18   52.02   1.48
            Cu (%)   562   0.01   0.50   0.09   0.01   0.12   1.37
OB14VM   OB14VM   -   Fe (%)   562   0.05   25.00   7.52   36.92   6.08   0.81
            Pb (%)   562   0.01   3.20   0.62   0.64   0.80   1.30
            Zn (%)   562   0.01   7.50   1.64   3.72   1.93   1.18
        Ag (g/t)   38   0.50   120.00   38.75   1,321.00   36.35   0.94
            Cu (%)   38   0.01   0.50   0.17   0.03   0.17   0.99
PUCVM   PUCVM   -   Fe (%)   38   2.89   15.00   7.96   14.27   3.78   0.47
            Pb (%)   38   0.01   2.50   0.61   0.63   0.80   1.31
            Zn (%)   38   0.03   4.00   0.79   1.63   1.28   1.61

 

SLR performed an independent capping analysis on some elements for four of the largest domains (SPB, SPP, SSM, and VM), as well as a visual validation of the block model in section and plan view. Log probability plots were inspected for each of these domains and SLR applied a capping grade using a combination of histograms, probability plots, and decile analyses. SLR found that most of the coefficients of variation (CV) after applying capping were low, with the exception of the CV values of more than 1.8 for lead in the SPB low grade, SPP high grade, SSM low grade, and SOP domains, for zinc in the SSM LG, VM LG, and SLB domains, and for copper in the SLB domain. Most of these domains are low grade domains with many very low grade values, and as a result, the CV is high. For the SLB, SLR recommends using an additional yield restriction during estimation to limit the spatial influence of the small population of high grade samples. In the SLR QP’s opinion, this is a minor issue that will not have a significant impact on the resource estimate as these domains represent less than one percent of the Mineral Resources. The SLR QP also noticed that Cu capping values for the SPB and SPP high grade domains could be slightly conservative and is of the opinion that there is an opportunity to increase the contained Cu by 2% to 4%. Figure 11-16 shows a probability plot, decile analysis, histogram, and disintegration analysis for Cu grades in the SPB high grade domain.

 

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Figure 11-16:        Copper Decile Analysis, Probability Plot, Histogram and Desintegration Analysis for Domain SPB HG

 

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SLR considers that the capping levels selected are appropriate. SLR offers the following conclusions and recommendations:

 

In general, the capping levels are reasonable, and suitable for the estimation of Mineral Resources.

 

Revisit copper capping levels for the SPB and SPP high grade domains with reconciliation data. There could be an opportunity to increase the contained Cu by 2% to 4%.

 

Report the metal loss as a result of capping high grades and assess the amount of metal in the upper decile and percentiles of the distribution to gain a better understanding of the amount of risk associated with the extreme values in each capping domain.

 

Investigate incorporating an additional yield restriction for SLB during estimation to limit the spatial influence of the small population of high grade samples.

 

Adjust capping values with production data when an accurate reconciliation process is established.

 

11.8 Compositing

 

Nexa composited the capped assays to 2.5 m with a 1.25 m tolerance, beginning at the collars. Small intervals were merged with the previous interval. Sample lengths range from 1.25 m to 3.75 m. Composites were tagged with rock type codes from the drill hole geology data. The majority of samples (93%) had a length from 90 cm to 1.5 m. Unsampled core intervals were set to zero for all elements. The composite length corresponds to half of the parent block size height for the deposit. Figure 11-17 illustrates a comparison of the mean relative error between length-weighted composites at different composite lengths versus assay means by mineralization domain. Based on this analysis, the two and half metre composites result in the best correlation between assay data and composites. Nexa generated statistics of the composites (Table 11-10).

 

 

Figure 11-17:         Composite Length Comparisons

 

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Table 11-10:          Estimation Domain Composite Statistics 

Nexa Resources S.A. – Cerro Lindo Mine

 

Estimation   Geological   Grade    Grade       Composited Values
Domain   Domain   Domain (units)   No. Samples   Minimum   Maximum   Mean   Variance   Std. Dev.   CV
SPBHAG       HG   Ag (g/t)   7,955   0.50   300.00   65.00   2,121.44   46.06   0.71
SPBLAG       LG   Ag (g/t)   15,868   0.50   100.00   13.51   108.06   10.39   0.77
SPBHCU       HG   Cu (%)   14,077   0.01   4.00   0.76   0.40   0.63   0.83
SPBLCU       LG   Cu (%)   9,823   0.01   1.00   0.13   0.01   0.12   0.90
SPBHFE    SPB   HG   Fe (%)   14,077   0.05   45.00   20.26   159.37   12.62   0.62
SPBLFE       LG   Fe (%)   9,823   0.05   45.00   18.26   104.76   10.24   0.56
SPBHPB       HG   Pb (%)   7,955   0.01   7.00   1.23   1.44   1.20   0.98
SPBLPB       LG   Pb (%)   15,868   0.01   4.50   0.30   0.26   0.51   1.71
SPBHZN       HG   Zn (%)   16,656   0.01   25.00   6.76   19.58   4.42   0.65
SPBLZN       LG   Zn (%)   7,352   0.01   8.00   1.50   2.24   1.50   1.00
SPPHAG       HG   Ag (g/t)   25,845   0.50   200.00   23.60   425.03   20.62   0.87
SPPLAG       LG   Ag (g/t)   12,474   0.50   30.00   4.57   8.04   2.83   0.62
SPPHCU       HG   Cu (%)   26,801   0.01   5.00   0.94   0.53   0.73   0.77
SPPLCU       LG   Cu (%)   11,499   0.01   1.07   0.11   0.01   0.09   0.82
SPPHFE    SPP   HG   Fe (%)   26,801   0.05   45.00   32.70   164.38   12.82   0.39
SPPLFE       LG   Fe (%)   11,499   0.05   45.00   32.50   148.90   12.20   0.38
SPPHPB       HG   Pb (%)   25,845   0.01   2.00   0.09   0.05   0.22   2.55
SPPLPB       LG   Pb (%)   12,474   0.01   0.20   0.02   0.00   0.02   1.24
SPPHZN       HG   Zn (%)   15,646   0.01   10.00   1.31   2.51   1.58   1.20
SPPLZN       LG   Zn (%)   22,743   0.01   1.70   0.12   0.01   0.11   0.92
SSMHAG       HG   Ag (g/t)   4,426   0.50   300.00   54.17   2,170.47   46.59   0.86
SSMLAG       LG   Ag (g/t)   8,744   0.50   90.00   8.62   54.02   7.35   0.85
SSMHCU       HG   Cu (%)   4,918   0.01   3.50   0.63   0.26   0.51   0.80
SSMLCU       LG   Cu (%)   8,272   0.01   1.10   0.10   0.01   0.09   0.95
SSMHFE    SSM   HG   Fe (%)   4,918   0.05   45.00   19.70   94.47   9.72   0.49
SSMLFE       LG   Fe (%)   8,272   0.05   45.00   19.15   88.92   9.43   0.49
SSMHPB       HG   Pb (%)   4,426   0.01   5.00   0.53   0.48   0.69   1.31
SSMLPB       LG   Pb (%)   8,744   0.01   1.50   0.06   0.01   0.09   1.47
SSMHZN       HG   Zn (%)   4,103   0.01   15.00   2.47   5.19   2.28   0.92
SSMLZN       LG   Zn (%)   8,983   0.01   1.50   0.11   0.03   0.16   1.49

 

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Estimation   Geological   Grade    Grade       Composited Values
Domain   Domain   Domain (units)   No. Samples   Minimum   Maximum   Mean   Variance   Std. Dev.   CV
VMHAG       HG   Ag (g/t)   2,244   0.50   400.00   87.27   4,779.79   69.14   0.79
VMLAG       LG   Ag (g/t)   3,420   0.50   100.00   18.38   175.45   13.25   0.72
VMHCU       HG   Cu (%)   3,027   0.01   3.00   0.51   0.19   0.44   0.87
VMLCU       LG   Cu (%)   2,560   0.01   0.50   0.07   0.00   0.06   0.86
VMHFE    VM   HG   Fe (%)   3,027   0.05   40.00   11.70   62.60   7.91   0.68
VMLFE       LG   Fe (%)   2,560   0.05   40.00   7.99   40.98   6.40   0.80
VMHPB       HG   Pb (%)   2,244   0.01   5.00   0.79   0.68   0.82   1.05
VMLPB       LG   Pb (%)   3,420   0.01   2.00   0.17   0.05   0.22   1.28
VMHZN       HG   Zn (%)   3,021   0.01   8.00   1.81   2.09   1.44   0.80
VMLZN       LG   Zn (%)   2,571   0.01   2.00   0.18   0.06   0.25   1.41
            Ag (g/t)   5,181   0.50   100.00   25.06   693.60   26.34   1.05
            Cu (%)   5,181   0.01   1.00   0.28   0.08   0.29   1.01
V   V   -   Fe (%)   5,181   0.05   40.00   9.20   71.83   8.48   0.92
            Pb (%)   5,181   0.01   1.00   0.21   0.07   0.26   1.22
            Zn (%)   5,181   0.01   2.00   0.40   0.31   0.56   1.40
            Ag (g/t)   472   0.50   80.00   11.64   220.10   14.84   1.27
            Cu (%)   472   0.01   2.50   0.66   0.40   0.63   0.96
SOP   SOP   -   Fe (%)   472   0.05   40.00   26.85   294.28   17.15   0.64
            Pb (%)   472   0.01   0.35   0.04   0.01   0.07   1.82
            Zn (%)   472   0.01   1.70   0.24   0.11   0.34   1.41
            Ag (g/t)   305   0.50   78.00   23.55   301.14   17.35   0.74
            Cu (%)   305   0.01   4.20   1.29   1.13   1.07   0.83
SOB   SOB   -   Fe (%)   305   0.05   45.00   21.86   144.54   12.02   0.55
            Pb (%)   305   0.01   0.90   0.17   0.05   0.23   1.37
            Zn (%)   305   0.01   5.30   1.12   1.71   1.31   1.17
            Ag (g/t)   199   0.50   130.00   26.59   1,415.80   37.63   1.42
            Cu (%)   199   0.01   0.90   0.10   0.05   0.23   2.29
SLB   SLB   -   Fe (%)   199   0.05   40.00   3.92   95.68   9.78   2.49
            Pb (%)   199   0.01   2.50   0.39   0.46   0.68   1.72
            Zn (%)   199   0.01   0.70   0.07   0.02   0.16   2.34
            Ag (g/t)   17   2.00   27.31   11.66   53.06   7.28   0.62
            Cu (%)   17   0.03   0.33   0.11   0.01   0.09   0.84
OB11VM   OB11VM   -   Fe (%)   17   6.67   12.00   8.75   2.78   1.67   0.19
            Pb (%)   17   0.01   0.47   0.16   0.02   0.13   0.82
            Zn (%)   17   0.46   3.89   1.72   1.21   1.10   0.64

 

Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
Technical Report Summary - January 29, 2021
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Estimation   Geological   Grade    Grade       Composited Values
Domain   Domain   Domain (units)   No. Samples   Minimum   Maximum   Mean   Variance   Std. Dev.   CV
            Ag (g/t)   77   2.69   149.89   28.88   1,024.43   32.01   1.11
            Cu (%)   77   0.01   0.51   0.13   0.01   0.11   0.84
OB12VM   OB12VM   -   Fe (%)   77   2.09   24.38   10.38   25.46   5.05   0.49
            Pb (%)   77   0.02   0.60   0.15   0.01   0.11   0.71
            Zn (%)   77   0.03   1.20   0.52   0.06   0.24   0.47
            Ag (g/t)   46   0.50   55.62   14.16   202.80   14.24   1.01
            Cu (%)   46   0.01   0.10   0.02   0.00   0.02   1.19
OB5BVM   OB5BVM   -   Fe (%)   46   0.05   8.00   3.21   3.70   1.92   0.60
            Pb (%)   46   0.01   0.99   0.28   0.08   0.28   1.01
            Zn (%)   46   0.01   5.80   1.96   2.35   1.53   0.78
            Ag (g/t)   224   0.50   200.00   35.81   2,111.82   45.95   1.28
            Cu (%)   224   0.01   0.49   0.09   0.01   0.10   1.14
OB14VM   OB14VM   -   Fe (%)   224   0.05   25.00   7.51   31.09   5.58   0.74
            Pb (%)   224   0.01   2.87   0.62   0.42   0.65   1.05
            Zn (%)   224   0.01   6.67   1.65   2.35   1.53   0.93
            Ag (g/t)   13   4.72   87.89   40.00   745.71   27.31   0.68
            Cu (%)   13   0.01   0.49   0.17   0.03   0.16   0.97
PUCVM   PUCVM   -   Fe (%)   13   3.31   14.05   7.82   10.44   3.23   0.41
            Pb (%)   13   0.01   2.06   0.62   0.42   0.65   1.05
            Zn (%)   13   0.05   3.50   0.80   1.00   1.00   1.25

 

SLR reviewed the composites and offers the following conclusions and recommendations:

 

The composite length is appropriate given the dominant sampling length and the 5 m block height, and is suitable to support Mineral Resource and Mineral Reserve estimation.

 

SLR recommends investigating density-weighted compositing.

 

11.9 Trend Analysis

 

11.9.1 Variography

 

Two-structure and three-structure spherical models in three directions were developed with experimental variograms for Zn, Pb, Cu, Ag, and Fe in Supervisor software. The variograms were calculated using the composites for the SPB, SPP, SSM, and VM domains. Figure 11-18 and Figure 11-19 show examples of variograms for Zn in SPB and Cu in SPP, respectively.

 

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Figure 11-18:           Zn Variogram for Mineralization SPB Domain

 

Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
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Figure 11-19:           Cu Variogram for Mineralization SPP Domain

 

Table 14-11 shows variogram parameters for the SPB and SPP domains

 

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Table 11-11:         Variogram Parameters 

Nexa Resources S.A. – Cerro Lindo Mine

 

Geological       Datamine Angles   Datamine Axes       Structure 1   Structure 2
Domain   Element   VANGLE1   VANGLE2   VANGLE3   VAXIS1   VAXIS2   VAXIS3   NUGGET   ST1PAR1   ST1PAR2   ST1PAR3   C1   ST2PAR1   ST2PAR2   ST2PAR3   C2
    Zn   -141.03   14.48   74.496   3   2   1   0.19   31   27   15   0.31   204   123   98   0.5
 SPB   Cu, Fe   -145.00   0.00   75   3   2   1   0.199   14   12   13   0.496   61   54   49   0.305
    Ag, Pb   -141.03   14.48   74.496   3   2   1   0.244   26   23   15   0.447   135   92   74   0.309
    Zn   -141.03   14.48   74.496   3   2   1   0.19   11   16   15   0.37   117   91   68   0.44
 SPP   Cu, Fe   -145.00   0.00   75   3   2   1   0.09   21   23   18   0.49   131   75   46   0.42
    Ag, Pb   -141.03   14.48   74.496   3   2   1   0.249   42   23   18   0.442   161   137   77   0.309

 

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11.10 Search Strategy and Grade Interpolation Parameters

 

Grades were interpolated into blocks on a parent cell basis using OK for the SPB and SPP domains. For all the other domains, ID³ interpolation method was used. All the variables, Zn, Cu, Pb, Ag and Fe, were interpolated, and estimates were not density weighted. All directions were based on Datamine’s dynamic anisotropy, which varies search ellipsoid orientations according to the trend of the mineralization domain.

 

The grade estimation was completed in three passes. Pass 1 uses a search radius equal to the variogram range; Pass 2 uses a search radius equal to 1.5 times the range of Pass 1; and Pass 3 uses a search radius of 10 times the range of Pass 1.

 

The search criteria are listed in Table 11-12 for zinc estimates and in Table 11-13 for copper estimates.

 

Table 11-12:           Zinc Estimation Parameters 

Nexa Resources S.A. – Cerro Lindo Mine

 

Estimation       Rotation
System AXIS
  Search Ellipse DIST   Pass 1   # Comp   Pass 2   # Comp   Pass 3   # Comp
Domain   Method   1   2   3   1   2   3   S-Vol   Min   Max   S-Vol   Min   Max   S-Vol   Min   Max
spbhzn   OK   3   2   1   35   25   15   1   10   14   1.5   6   12   10   1   6
spblzn   OK   3   2   1   35   25   15   1   10   14   1.5   6   12   10   1   6
spphzn   OK   3   2   1   35   25   15   1   8   12   1.5   5   10   10   1   4
spplzn   OK   3   2   1   35   25   15   1   8   12   1.5   5   10   10   1   5
ssmhzn   IDW3   3   2   1   35   25   15   1   10   14   1.5   6   12   10   1   6
ssmlzn   IDW3   3   2   1   35   25   15   1   10   14   1.5   6   12   10   1   6
vmhzn   IDW3   3   2   1   35   25   15   1   10   14   1.5   6   12   10   1   6
vmlzn   IDW3   3   2   1   35   25   15   1   8   10   1.5   5   10   10   1   4
v   IDW3   3   2   1   25   10   10   1   8   12   1.5   5   10   10   1   4
sop   IDW3   3   2   1   25   20   10   1   8   12   1.5   5   10   10   1   4
sob   IDW3   3   2   1   30   15   10   1   6   10   1.5   4   7   10   1   4
slb   IDW3   3   2   1   30   15   10   1   6   8   1.5   4   5   10   1   3
ob11vm   IDW3   3   2   1   35   20   10   1   6   8   1.5   4   6   10   1   3
ob12vm   IDW3   3   2   1   35   25   15   1   10   14   1.5   6   12   10   1   6
ob5bvm   IDW3   3   2   1   25   20   10   1   8   12   1.5   5   10   10   1   4
ob14vm   IDW3   3   2   1   25   15   10   1   10   14   2   5   8   10   1   4
pucvm   IDW3   3   2   1   35   25   15   1   10   14   1.5   6   12   10   1   6

 

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Table 11-13: Copper Estimation Parameters 

Nexa Resources S.A. – Cerro Lindo Mine

Estimation       Rotation
System AXIS
  Search Ellipse DIST   Pass 1   # Comp   Pass 2   # Comp   Pass 3   # Comp
Domain   Method   1   2   3   1   2   3   S-Vol   Min   Max   S-Vol   Min   Max   S-Vol   Min   Max
spbhcu   OK   3   2   1   35   25   15   1   10   14   1.5   6   12   10   1   6
spblcu   OK   3   2   1   35   25   15   1   10   14   1.5   6   12   10   1   6
spphcu   OK   3   2   1   35   25   15   1   10   14   1.5   6   12   10   1   6
spplcu   OK   3   2   1   35   25   15   1   9   12   1.5   5   10   10   1   4
ssmhcu   IDW3   3   2   1   35   25   15   1   10   14   1.5   6   12   10   1   6
ssmlcu   IDW3   3   2   1   35   25   15   1   10   14   1.5   6   12   10   1   6
vmhcu   IDW3   3   2   1   35   25   15   1   10   14   1.5   6   12   10   1   6
vmlcu   IDW3   3   2   1   35   25   15   1   10   14   1.5   6   12   15   1   6
v   IDW3   3   2   1   25   20   10   1   8   12   1.5   5   10   10   1   4
sop   IDW3   3   2   1   25   20   10   1   8   12   1.5   5   10   10   1   4
sob   IDW3   3   2   1   30   15   10   1   6   8   1.5   4   6   10   1   4
slb   IDW3   3   2   1   30   15   10   1   6   8   1.5   4   5   10   1   3
ob11vm   IDW3   3   2   1   35   20   15   1   6   10   1.5   4   8   10   1   3
ob12vm   IDW3   3   2   1   35   25   15   1   10   14   1.5   6   12   10   1   6
ob5bvm   IDW3   3   2   1   35   25   15   1   10   14   1.5   6   12   10   1   6
ob14vm   IDW3   3   2   1   35   15   10   1   10   14   2   5   8   10   1   4
pucvm   IDW3   3   2   1   35   25   15   1   10   14   1.5   6   12   10   1   6

 

11.11 Bulk Density

 

The Cerro Lindo deposit has 4,410 density determinations in the mineralization domains and 4,114 samples in the wallrock that were used for resource estimates. A summary of the density measurements taken by geological domains is presented in Table 11-14 and the density sample location is shown in Figure 11-20. A buffer of 20 m was used to select and review the density data, totalling 1,215 density measurements, in the wallrock. Nexa interpolated the density values for the SPP, SPB, SSM, VM, and V domains and assigned an average density value for SOP, SOB, SLB, and wallrock as shown in Table 11-15.

 

Density measurements were not available for the SOP, SOB, and SLB domains. Nexa applied the lower quartile of the SPP and SPB density measurements assuming a lower density as a result of the oxidization and leaching processes. SLR recommends generating density data for the SOP, SOB, and SLB domains that currently do not have density tests available. In the SLR QP’s opinion, this will not have a significant impact on the resource estimate as these domains represent less than one percent of the Mineral Resources. 

 

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Table 11-14:           Density Data

Nexa Resources S.A. – Cerro Lindo Mine

 

Geological
Domain
  No.
Samples
    Uncapped values   Std. Dev.   CV
    Minimum   Maximum   Density (t/m³)   Variance    
SPB   915   1.78   6.74   4.23   0.32   0.56   0.13
                             
SPP   2,031   1.90   5.21   4.36   0.29   0.54   0.12
                             
SSM   883   2.34   4.93   3.39   0.20   0.45   0.13
                             
VM   382   2.14   4.87   3.11   0.18   0.42   0.14
                             
V   118   1.89   4.90   3.02   0.23   0.48   0.16
                             
DIKE   81   2.35   4.87   3.32   0.61   0.78   0.24
                             
Total   4,410                        

 

Table 11-15:           Assigned Density Values

Nexa Resources S.A. – Cerro Lindo Mine

 

Geological
Domain
 

Density

(t/m³)

SOP   3.50
     
SOB   3.50
     
SLB   3.00
     
Wallrock   2.89

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Figure 11 20:            Density Sample Location by Geological Domains

 

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11.11.1 Treatment of High Density Values

 

Nexa applied low and high capping values to density measurements in the SPB, SPP, SSM, VM, V, and Dike geological domains in order to limit the influence of a small amount of outlier values located in the lower and upper tail of the density distributions (Figure 11-21). A summary of the capping levels is shown in Table 11-16.

 

Table 11-16:          Density Capping Values

Nexa Resources S.A. – Cerro Lindo Mine

 

Geological
Domain
  CLI   Lower Capping Value   Upper Capping Value
    Density (t/m3)   Density (t/m3)
SPB   1   2.70   4.90
             
SPP   2   2.70   5.00
             
SSM   3   2.70   4.00
             
VM   4   2.70   3.60
             
V   5   2.70   3.50
             
DIKE   10   2.50   2.85

 

 

 

 

Figure 11-21:            Density Capping Analysis for SPB Domain

 

For the SPP, SPB, SSM, VM, and V geological domains, Nexa interpolated the density values using an ID3 method. The search ellipsoids for density generally have a sub-vertical pancake shape with the same orientation as the mineralization and the grade estimate. The average density value is 4.42 t/m³ for the SPB blocks and 4.49 t/m³ for the SPP blocks.

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Block estimation parameters for bulk density are shown in Table 11-17.

 

Table 11-17:            Block Estimation Parameters for Bulk Density

Nexa Resources S.A. – Cerro Lindo Mine

 

Pass Name   Domain   Type   Search
X (m)
  Search
Y (m)
  Search
Z (m)
  Min
Samples
  Max
Samples
  Max
Samples
Per Hole
  Lower
Sample
Cap (t/m³)
  Upper
Sample
Cap
(t/m³)
1   SPB   ID³   50   50   25   3   14   2   2.70   4.90
                                         
2   SPB   ID³   50   50   25   3   14   2   2.70   4.90
                                         
3   SPB   ID³   50   50   25   1   14   2   2.70   4.90
                                         
1   SPP   ID³   50   50   25   3   14   2   2.70   5.00
                                         
2   SPP   ID³   50   50   25   3   14   2   2.70   5.00
                                         
3   SPP   ID³   50   50   25   1   14   2   2.70   5.00
                                         
1   SSM   ID³   50   50   25   3   14   2   2.70   4.00
                                         
2   SSM   ID³   50   50   25   3   14   2   2.70   4.00
                                         
3   SSM   ID³   50   50   25   1   14   2   2.70   4.00
                                         
1   VM   ID³   50   50   25   3   14   2   2.70   3.60
                                         
2   VM   ID³   50   50   25   3   14   2   2.70   3.60
                                         
3   VM   ID³   50   50   25   1   14   2   2.70   3.60
                                         
1   V   ID³   50   50   25   3   14   2   2.70   3.50
                                         
2   V   ID³   50   50   25   3   14   2   2.70   3.50
                                         
3   V   ID³   50   50   25   1   14   2   2.70   3.50

 

Nexa validated the density estimate by examining the block density distribution against the samples, stepping across the model in vertical section and plan view and preparing swath plots. A statistical comparison of density sample populations to block populations is shown in Table 11-18. A plan view comparing density sample values to block values is shown in Figure 11-22. Swath plots of ID³ density estimates versus nearest neighbour (NN) density estimates, as well as sample density values, are shown in Figure 11-23, Figure 11-24, Figure 11-25, and Figure 11-26.

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Table 11-18:            Statistical Comparison of Blocks versus Composites: Density

Nexa Resources S.A. – Cerro Lindo Mine

 

Dominio    Pass    Numero de   DENS_NN   DENS_IDW3   Dif. Rel. de medias
    Bloques   Media   Cv   Media   Cv   NN_IDW3(%)
SPB    1   1355059   4.391   0.106   4.390   0.071   0.02%
  2   2293725   4.402   0.107   4.406   0.062   -0.10%
  3   1514578   4.508   0.085   4.466   0.054   0.93%
  Total   5163362   4.432   0.101   4.421   0.063   0.26%
                         
    Pass    Numero de   DENS_NN   DENS_IDW3   Dif. Rel. de medias
      Bloques   Media Cv   Media   Cv   NN_IDW3(%)
SPP    1   2034721   4.497   0.118   4.497   0.082   0.01%
  2   4489737   4.466   0.128   4.482   0.082   -0.36%
  3   2946554   4.531   0.110   4.503   0.063   0.63%
  Total   9471012   4.494   0.121   4.492   0.077   0.04%
                         
    Pass    Numero de   DENS_NN   DENS_IDW3   Dif. Rel. de medias
      Bloques   Media   Cv   Media   Cv   NN_IDW3(%)
SSM    1   488673   3.470   0.111   3.439   0.077   0.90%
  2   1489523   3.498   0.114   3.485   0.072   0.36%
  3   1997431   3.625   0.102   3.514   0.052   3.11%
  Total   3975627   3.562   0.109   3.495   0.063   1.90%
                         
    Pass    Numero de   DENS_NN   DENS_IDW3   Dif. Rel. de medias
      Bloques   Media Cv   Media   Cv   NN_IDW3(%)
VM    1   206192   3.056   0.099   3.049   0.067   0.20%
  2   334679   3.094 0.096   3.081   0.062   0.41%
  3   1506194   3.183 0.095   3.118   0.059   2.05%
  Total   2047065   3.156   0.097   3.106   0.061   1.61%
                         
    Pass    Numero de   DENS_NN   DENS_IDW3   Dif. Rel. de medias
      Bloques   Media   Cv   Media   Cv   NN_IDW3(%)
V(ENCL)    1   8348   3.201   0.104   3.193   0.077   0.24%
  2   48792   3.063   0.103   3.052   0.073   0.36%
  3   268839   3.111   0.102   2.984   0.049   4.19%
  Total   325979   3.107   0.103   2.999   0.056   3.54%

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Figure 11-23:           SPB Swath Plots – Density Values

 

 

 

Figure 11-24:           SPP Swath Plots – Density Values

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Figure 11-25:           SSM Swath Plots – Density Values

 

 

 

Figure 11-26:           VM Swath Plots – Density Values

 

The SLR QP reviewed the density data distribution and location and is of the opinion that the density values are reasonable for the style of mineralization and the density samples are well distributed in the largest domains (SPP and SPB) throughout the deposit.

 

As reserves and resources are extended towards extremities of the mineralization, SLR recommends collecting more density samples in these areas, especially in areas with no density samples. Additional density sampling will allow a more accurate definition of tonnes in these areas, as mined-out zones in the centre of the deposit have higher density values. SLR recommends reviewing all the reserves stopes and collect density samples on these zones or in the proximities.

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11.12 Block Models

 

Cerro Lindo wireframes were filled with blocks in Datamine Studio RM. The block model was sub-celled at wireframes boundaries with parent cells measuring 5 m by 5 m by 5 m and minimum sub-cell sizes of 0.5 m by 0.5 m by 0.5 m. The block model setup is shown in Table 11-19 and a description of the block model attributes is provided in Table 11-20.

 

Table 11-19:           Block Model Setup

Nexa Resources S.A. – Cerro Lindo Mine

 

Parameter   X   Y   Z
Origin (m)   387,700   8,552,000   700
Block Size (m)   5   5   5
Min. Sub Block size (m)   0.5   0.5   0.5
Number of Blocks   538   420   322

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Table 11-20:           Block Model Attribute Descriptions

Nexa Resources S.A. – Cerro Lindo Mine

 

Field   Description   Field   Description   Field   Description
IJK   ID Block   SHELLZN   SPBHZN Inside High Grade Zn   SHELLAG SPBHAG   Inside High Grade Ag
XC   East Block Centroid       SPBLZN Inside Low Grade Zn     SPBLAG   Inside Low Grade Ag
YC   North Block Centroid       SPPHZN Inside High Grade Zn     SPPHAG   Inside High Grade Ag
ZC   Elevation Block Centroid       SPPLZN Inside Low Grade Zn     SPPLAG   Inside Low Grade Ag
XINC   Block Size on East Axis       SSMHZN Inside High Grade Zn     SSMHAG   Inside High Grade Ag
YINC   Block Size on North Axis       SSMLZN Inside Low Grade Zn     SSMLAG   Inside Low Grade Ag
ZINC   Block Size on Elevation Axis       VMHZN Inside High Grade Zn     VMHAG   Inside High Grade Ag
CLI/OB   1 SPB       VMLZN Inside Low Grade Zn     VMLAG   Inside Low Grade Ag
    2 SPP       V -     V   -
    3 SSM       SOP -     SOP   -
    4 VM       SOB -     SOB   -
    5 V (enclave)       SLB -     SLB   -
    6 SOP       OB11VM -     OB11VM   -
    7 SOB       OB12VM -     OB12VM   -
    8 SLB       OB5BVM -     OB5BVM   -
    11 OB11VM       OB14VM -     OB14VM   -
    12 OB12VM       PUCVM -     PUCVM   -
                      Estimated    
                      density for    
                      SPB, SPP,    
                      SSM and    
    13 OB5BVM       SPBHCU Inside High Grade Cu   DENSITY VM and    
                      mean    
                      values for    
                      all other    
          SHELLCU           domains    
    14 OB14VM       SPBLCU Inside Low Grade Cu          
    15 PUCVM       SPPHCU Inside High Grade Cu          
                      Estimated    
CGEOCD   9 SPB       SPPLCU Inside Low Grade Cu   ZN Zn(%)    
                      Estimated    
    6 SPP       SSMHCU Inside High Grade Cu   PB Pb(%)    
                      Estimated    
    5 SSM       SSMLCU Inside Low Grade Cu   CU Cu(%)    
                      Estimated    
    28 VM       VMHCU Inside High Grade Cu   AG Ag(g/t)    
                      Estimated    
    29 V (enclave)       VMLCU Inside Low Grade Cu   FE Fe(%)    
    7 SOP       V -   CLASS 1   Measured
    10 SOB       SOP -     2   Indicated
    11 SLB       SOB -     3   Inferred
                      4   Not Classified
    28 OB11VM       SLB -        
                         
    28 OB12VM       OB11VM -          
    28 OB5BVM       OB12VM -          
    28 OB14VM       OB5BVM -          
    28 PUCVM       OB14VM -          
              PUCVM -          

 

The SLR QP is of the opinion that the block size is appropriate, based on the drill spacing and proposed mining method, and is suitable to support the estimation of Mineral Resources and Mineral Reserves.

 

11.13 Net Smelter Return and Cut-off Value

 

An NSR cut-off value was determined using the Mineral Resource metal prices, metal recoveries, transport, treatment, and refining costs, as well as mine operating cost. Metal prices used for Mineral Resources are based on consensus, long term forecasts from banks, financial institutions, and other sources.

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The cut-off value used for the Resource estimate is based on an NSR value, in units of US$/t, which can be directly compared to operating unit costs. The NSR formula is:

 

NSR = Gross Revenue – Offsite Charges
Tonnes Processed

 

Cut-off costs and NSR parameters are summarized in Table 11-21. The break even NSR cut-off value for SLS and C&F mining methods are $33.56/t processed and $49.90/t processed respectively.

 

Table 11-21:          Resource NSR Data

Nexa Resources S.A. – Cerro Lindo Mine

 

Item   Units   SLS   C&F
Net Metallurgical Recovery *        
Zn   %   88.13   88.13
Pb   %   68.58   68.58
Cu   %   86.30   86.30
Ag   %   68.78   68.78
Cu Concentrate Payable %            
Cu   %   96.7   96.7
Ag   %   90.0   90.0
Pb Concentrate Payable %            
Pb   %   95.0   95.0
Ag   %   95.0   95.0
Zn Concentrate Payable %            
Zn   %   95.8   95.8
Ag   %   70.0   70.0
Metal Prices            
Zn   US$/lb   1.30   1.30
Pb   US$/lb   1.02   1.02
Cu   US$/lb   3.37   3.37
Ag   US$/oz   19.38   19.38
Charges            
Logistics and TC            
Zn Concentrate   US$/t conc   321.0   321.0
Pb Concentrate   US$/t conc   251.0   251.0
Cu Concentrate   US$/t conc   245.0   245.0
Integrated Zn            
Conversion Cost   US$/t Zn prod   447.0   447.0
Premium   US$/t Zn Prod   217.0   217.0

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Item   Units   SLS   C&F
Refining Cost            
Ag in Pb conc   US$/oz   1.00   1.01
Ag in Cu conc   US$/oz   0.50   0.51
Operating Costs            
Mining   US$/t proc.   21.00   37.34
Processing + Maintenance   US$/t proc.   10.42   10.42
G&A   US$/t proc.   2.14   2.14
Total   US$/t proc.   33.56   49.90

 

Nexa reviewed supply and demand projections for zinc, lead, and copper, as well as consensus long term (ten year) metal price forecasts. SLR verified that Nexa’s selected metal prices for estimating Mineral Reserves are in line with independent forecasts from banks and other lenders. Prices selected for Mineral Resource estimation are 15% higher, which is in line with typical industry practice.

 

The average NSR factors are calculated using the LOM revenue contribution from each metal net of off-site costs and factors, divided by the reserve grade for that metal, and are indicative of the relative contribution of each metal unit to the economics of the Mine. For most metals, a variable recovery (as a function of head grade) was used, and therefore the average NSR factors should not be applied to head grades without considering the head grade versus recovery relationship. NSR factors are therefore variable by head grade, with average NSR factors summarized in Table 11-22. The head grade and recovery curves are presented in Figure 11-27, Figure 11-28, and Figure 11-29.

 

Table 11-22:         Average NSR Factors

Nexa Resources S.A. – Cerro Lindo Mine

 

Item   Units   Value
Zn   US$/%   20.56
Pb   US$/%   14.12
Cu   US$/%   55.91
Ag   US$/oz   12.59

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Figure 11-27:           Zinc Recovery

 

 

 

Figure 11-28:                Copper Recovery

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Figure 11-29:            Lead Recovery

 

11.14 Classification

 

Definitions for resource categories used in this report are those defined by SEC in S-K 1300. Mineral Resources are classified into Measured, Indicated, and Inferred categories.

 

Mineral Resource classification for the SPP and SPB domains is based on the number of drill holes and distances determined by variogram ranges, geological and grade continuity, and well production experience. The SSM and VM domain blocks were classified based on the continuity of the orebodies and recent production experience. The SSM and VM mineralization is more discontinuous than the SPB and SPP domains, as it occurs more as patches or stringers. The Measured and Indicated classification was more restrictive.

 

Flagging of the blocks by drill hole distances was performed by using a search pass with dimensions and parameters for each category. The first pass involved a numerical block classification based on the number of drill holes and search radii followed by a post processing of the classification to remove isolated small patches and irregular shapes, yielding more realistic shapes from a mining perspective.

 

The classification of the Mineral Resource estimate was applied as follows:

 

Measured Mineral Resources: Measured blocks were defined, for SPP and SPB domains, the largest contributors of the Measured Resources, using a search radius of 26 m by 26 m by 12 m, and for SSM and VM domains, minor contributors of the Measured Resources (<1%), using a search radius of 13 m by 13 m by 7 m, with at least three holes within each estimation domains, and supported with data of a low level of uncertainty as follows:

 

o Drilling, sampling, and sample preparation and assay procedures: follow industry standards and best practices.

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o Reliability of sampling data: Excellent database integrity and representativity based on SLR’s independent data verification and validation, as well as no significant bias observed in QA/QC analysis results.

 

o Confidence in interpretation and modelling of geological and estimation domains: SPB and SPP (the major contributors to the Mineral Resources) show good agreement and some SSM and VM domain solids show good agreement with the drill holes and underground mapping.

 

o Geology and grade continuity: Based on drilling and underground mapping, trend analysis and variography, SPB and SPP domains show good geology and grade continuity.

 

o Confidence in estimation of block grades for the main metals: Block grades correlate well with composite data, statistically and spatially, locally and globally, as well as with production reconciliation.

 

o Acceptable bulk density representativity: Sufficient density measurements for most of the SPP and SPB domains.

 

o Well supported drilling spacing criteria: Based on three drill holes and 50% to 70% of the range of the variograms.

 

o Production experience in the deposit: More than a decade of production experience mining the SPP and SPB domains.

 

o Good reconciliation performance: Block grades reconcile well with plant data, overall, within 10%.

 

Indicated Mineral Resources: Indicated blocks were defined, for SPP and SPB domains, the largest contributors of the Indicated Resources, using a search radius of 50 m by 50 m by 13 m, and for SSM and VM domains, minor contributors of the Indicated Resources (<35%), using a search radius of 25 m by 25 m by 13 m, with at least three holes within each estimation domains, and supported with data of a low and/or medium level of uncertainty as follows:

 

o Drilling, sampling, and sample preparation and assay procedures: follow industry standards and best practices.

 

o Reliability of sampling data: Excellent database integrity and representativity based on SLR’s independent data verification and validation, as well as no significant bias observed in QA/QC analysis results.

 

o Confidence in interpretation and modelling of geological and estimation domains: SPB and SPP (the major contributors to the Mineral Resources) show good agreement and some SSM and VM domain solids show relatively acceptable agreement with the drill holes and underground mapping where the density of drill holes is less, particularly at the mineralization edges.

 

o Geology and Grade Continuity: Based on drilling and underground mapping, trend analysis and variography, SPB and SPP domains show good geology and grade continuity. SSM and VM domains geometries are less well defined and geological and grade continuity is less because mineralization is presented in patches.

 

o Confidence in estimation of block grades for the main metals: Block grades correlate well with composite data, statistically and spatially, locally and globally, as well as with production reconciliation.

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o Reasonable bulk density representativity: Sufficient density measurements were taken for most of the SPP and SPB domains. Reasonable density measurements for some of the SSM and VM areas, with limited density measurements available at the mineralization edges.

 

o Well supported drilling spacing criteria: Based on three drill holes and 60% to 80% of the range of the variograms.

 

o Production experience in the deposit: More than a decade of production experience mining the SPP and SPB domains. Moderate experience with SSM and VM, increasing in the last five years as these domains are located at the mineralization edges.

 

o Good reconciliation performance: Block grades reconcile well with plant data, overall, within 10%.

 

Inferred Mineral Resources: Inferred blocks were defined, for SPP and SPB domains, using a search radius of 79 m by 79 m by 40 m, for SSM and VM domains, the largest contributors (>76%) of the Inferred Resources, using a search radius of 50 m by 50 m by 25 m, with at least two holes within each estimation domains, for all the other domains (SBO, SOP, SLB, V) representing less than 13% of the Inferred Resources, using a search radius of 50 m by 50 m by 25 m, with at least three holes within each estimation domains and supported with data of a low and/or medium and/or high level of uncertainty as follows:

 

o Drilling, sampling, and sample preparation and assay procedures: follow industry standards and best practices.

 

o Reliability of sampling data: Excellent database integrity and representativity based on SLR’s independent data verification and validation, as well as no significant bias observed in QA/QC analysis results for SPP, SPB, SSM, and VM. Less data is available for the SOB, SOP, SBL, and V domains.

 

o Confidence in interpretation and modelling of geological and estimation domains: SPB and SPP (the major contributors to the Mineral Resources) show good agreement and some SSM and VM domain solids show relatively acceptable agreement with the drill holes and underground mapping where the density of drill holes is less, particularly at the mineralization edges.

 

o Geology and grade continuity: Based on drilling and underground mapping, trend analysis and variography, SPB and SPP domains show good geology and grade continuity. SSM, VM, SOB, SOP, SBL, and V domains geometries are less well defined, and geological and grade continuity for these domains is less continuous and more variable.

 

o Confidence in estimation of block grades for the main metals: Block grades correlate reasonably well with composite data, statistically and spatially, locally and globally, as well as with production reconciliation.

 

o Bulk density representativity is reasonable for most of the domains: Density measurements for SOB, SOP, and SLB domains are required.

 

o Infill drilling: More drilling is required to determine continuity of mineralization in areas of wide drill spacing in order to upgrade Inferred Resources to Indicated. Inferred drilling spacing was defined based on 80% to 90% of the variogram range.

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o Production experience in the deposit: More than a decade of production experience mining the SPP and SPB domains. Moderate experience with SSM and VM, increasing in the last five years as these domains are located at the mineralization edges. Limited experience with SOB, SOP, and SLB domains with challenging metallurgical recovery, however, these domains are localized and should be blended before the material is sent to the plant.

 

Figure 11-30 and Figure 11-31 show histogram validations of the classification based on the distance of each block to its closest sample for the SPB/SPP and SSM/VM domains, respectively. Figure 11-32 shows a plan view of the final model classification.

 

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Figure 11-30:            Validation of Classification (SPB and SPP)

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Figure 11-31:            Validation of Classification (SSM and VM)

 

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Figure 11 32:            Final Classification Designation 

 

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The SLR QP has reviewed the classification and considers it to be reasonable, however, the SLR QP recommends monitoring the production data to ensure that the selected drill spacing for SSM and VM is appropriate to support detailed mine planning, as these domains show less grade continuity and more grade variability than the massive sulphide domains.

 

The SLR QP is of the opinion that the definitions for Mineral Resources used in this report have been classified in accordance with the definitions for Mineral Resources in S-K 1300, which are consistent with Canadian Institute of Mining, Metallurgy and Petroleum (CIM) Definition Standards for Mineral Resources and Mineral Reserves dated May 10, 2014 (CIM (2014) definitions).

 

11.15 Block Model Validation

 

Nexa and SLR carried out a number of block model validation procedures including:

 

Comparison between OK, NN, and composite mean grades (Table 11-23).

Swath plots (Figure 11-33 and Figure 11-34).

Visual inspection of composite versus block grades (Figure 11-35 and Figure 11-36).

Reconciliation with the plant (Figure 11-37).

 

Nexa compared the OK grade estimates with NN and composite mean grades. Overall, the differences were below 5% for the comparison between the OK and NN grades. Swath plots showed good correlation of the grades locally, without significant bias.

 

The visual inspection of composite and block grades revealed that the spatial grade correlation is good for zinc and copper and reasonable for lead and silver.

 

Swath plots (Figure 11-33 and Figure 11-34) show acceptable agreement between composite, NN, and OK estimates for zinc and copper block grades.

 

The resource model reconciles well with the plant. In 2018, the plant processed 91% of the total resource model tonnage, 100% of the zinc grade, and 112% of the copper grade. For 2019, the plant processed 93% of the total resource model tonnage, 101% of the zinc grade, and 105% of the copper grade.

 

SLR’s validation results suggest that the grade estimates for zinc, copper, lead, and silver are reasonable, and that the block model is suitable to support Mineral Resource and Mineral Reserve estimation.

 

Table 11-23:           Comparison Between Estimates (OK/ID³), NN and Composite Means

Nexa Resources S.A. – Cerro Lindo Mine

 

Domain   Grade   No. Blocks   NN   OK   Dif. Rel.
NN_OK(%)
  IDW3   Dif. Rel.
NN_ID3(%)
      Mean   CV   Mean   CV     Mean   CV  
SPBH   Zn (%)   2,986,839   6.70   0.64   6.68   0.45   0%   6.71   0.48   0%
  Pb (%)   1,818,994   1.22   0.96   1.22   0.59   0%   1.23   0.67   0%
  Cu (%)   3,078,056   0.79   0.81   0.77   0.41   2%   0.78   0.51   2%
  Ag (g/t)   1,818,994   65.37   0.69   64.73   0.38   1%   64.81   0.45   1%
  Fe (%)   3,078,056   19.03   0.70   19.18   0.48   -1%   19.06   0.55   0%

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Domain   Grade   No. Blocks   NN   OK   Dif. Rel.
NN_OK(%)
  IDW3   Dif. Rel.
NN_ID3(%)
      Mean   CV   Mean   CV     Mean   CV  
SPBL   Zn (%)   2,176,523   1.49   0.97   1.53   0.52   -3%   1.49   0.61   0%
  Pb (%)   3,344,368   0.30   1.69   0.30   0.98   0%   0.31   1.11   -1%
  Cu (%)   2,085,306   0.13   0.85   0.13   0.36   -2%   0.13   0.46   -2%
  Ag (g/t)   3,344,368   13.23   0.74   13.36   0.40   -1%   13.26   0.46   0%
  Fe (%)   2,085,306   17.80   0.60   17.84   0.40   0%   17.83   0.46   0%
SPPH   Zn (%)   3,642,789   1.34   1.20   1.30   0.65   3%   1.33   0.79   1%
  Pb (%)   5,714,720   0.08   2.60   0.08   1.45   -1%   0.08   1.68   2%
  Cu (%)   6,024,909   0.90   0.81   0.89   0.53   1%   0.90   0.57   0%
  Ag (g/t)   5,714,720   22.99   0.87   23.01   0.47   0%   23.04   0.53   0%
  Fe (%)   6,024,909   31.26   0.44   31.39   0.27   0%   31.54   0.30   -1%
SPPL   Zn (%)   5,828,223   0.10   0.96   0.10   0.56   -3%   0.10   0.66   -1%
  Pb (%)   3,756,292   0.01   1.31   0.01   0.80   -1%   0.01   0.93   0%
  Cu (%)   3,446,103   0.10   0.75   0.11   0.44   -2%   0.10   0.50   0%
  Ag (g/t)   3,756,292   4.12   0.62   4.17   0.36   -1%   4.13   0.43   0%
  Fe (%)   3,446,103   31.78   0.39   31.84   0.26   0%   31.95   0.29   -1%
SSMH   Zn (%)   1,208,290   2.41   0.91   2.48   0.52   -3%   2.46   0.63   -2%
  Pb (%)   1,332,857   0.55   1.33   0.55   0.67   -1%   0.55   0.88   -1%
  Cu (%)   1,598,363   0.64   0.77   0.63   0.43   2%   0.63   0.53   2%
  Ag (g/t)   1,332,857   55.86   0.87   55.94   0.44   0%   56.08   0.58   0%
  Fe (%)   1,598,363   19.09   0.53   19.21   0.34   -1%   19.14   0.41   0%
SSML   Zn (%)   2,767,337   0.09   1.54   0.09   0.95   -4%   0.09   1.10   0%
  Pb (%)   2,642,770   0.05   1.56   0.05   0.89   -5%   0.05   1.09   -2%
  Cu (%)   2,377,264   0.09   0.99   0.09   0.57   -3%   0.09   0.68   1%
  Ag (g/t)   2,642,770   7.02   0.92   7.31   0.58   -4%   7.11   0.68   -1%
  Fe (%)   2,377,264   18.81   0.53   19.11   0.36   -2%   18.86   0.42   0%
VMH   Zn (%)   915,742   1.70   0.81   1.70   0.43   0%   1.72   0.55   -1%
  Pb (%)   614,140   0.78   1.02   0.78   0.55   1%   0.79   0.72   0%
  Cu (%)   948,663   0.52   0.85   0.51   0.44   3%   0.52   0.61   0%
  Ag (g/t)   614,140   93.52   0.78   91.28   0.44   2%   93.16   0.57   0%
  Fe (%)   948,663   11.75   0.68   11.85   0.40   -1%   11.78   0.52   0%

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Domain   Grade   No. Blocks   NN   OK   Dif. Rel.
NN_OK(%)
  IDW3   Dif. Rel.
NN_ID3(%)
      Mean   CV   Mean   CV     Mean   CV  
VML   Zn (%)   852,757   0.18   1.30   0.19   0.76   -3%   0.18   0.90   -3%
  Pb (%)   1,154,359   0.18   1.37   0.18   0.82   2%   0.19   1.03   -4%
  Cu (%)   819,836   0.07   0.81   0.07   0.39   -5%   0.07   0.55   -3%
  Ag (g/t)   1,154,359   17.13   0.78   17.39   0.42   -2%   17.49   0.52   -2%
  Fe (%)   819,836   7.33   0.84   7.45   0.55   -2%   7.25   0.68   1%
V   Zn (%)   325,979   0.39   1.43   0.39   1.02   -1%   0.38   1.16   0%
  Pb (%)   325,979   0.19   1.30   0.20   0.74   -3%   0.19   0.98   0%
  Cu (%)   325,979   0.26   1.04   0.27   0.63   -3%   0.26   0.78   0%
  Ag (g/t)   325,979   22.96   1.11   23.87   0.60   -4%   22.92   0.81   0%
  Fe (%)   325,979   9.28   0.95   9.33   0.58   -1%   9.26   0.73   0%
SOP   Zn (%)   45,313   0.22   1.49   0.22   0.95   -1%   0.22   1.12   -1%
  Pb (%)   45,313   0.04   1.79   0.04   1.10   1%   0.04   1.30   5%
  Cu (%)   45,313   0.54   1.10   0.54   0.84   -1%   0.55   0.87   -2%
  Ag (g/t)   45,313   11.50   1.25   11.28   0.85   2%   11.15   0.95   3%
  Fe (%)   45,313   26.99   0.61   27.91   0.44   -3%   27.80   0.49   -3%
SOB   Zn (%)   51,570   0.91   1.39   0.92   0.99   0%   0.91   1.11   1%
  Pb (%)   51,570   0.17   1.27   0.18   0.87   -3%   0.17   0.98   -1%
  Cu (%)   51,570   1.07   0.97   1.12   0.60   -5%   1.09   0.70   -1%
  Ag (g/t)   51,570   21.32   0.79   21.76   0.48   -2%   21.45   0.55   -1%
  Fe (%)   51,570   18.96   0.66   19.14   0.51   -1%   19.07   0.55   -1%
SLB   Zn (%)   46,333   0.07   2.58   0.08   1.79   -12%   0.06   2.04   6%
  Pb (%)   46,333   0.37   1.78   0.44   1.17   -17%   0.39   1.52   -3%
  Cu (%)   46,333   0.03   3.72   0.04   2.46   -20%   0.03   3.14   4%
  Ag (g/t)   46,333   22.59   1.46   25.36   0.97   -12%   22.48   1.30   0%
  Fe (%)   46,333   1.93   3.25   2.37   2.09   -20%   1.85   2.59   4%
OB11VM   Zn (%)   57,986   2.02   0.54   1.91   0.47   5%   2.05   0.48   -2%
  Pb (%)   57,986   0.13   0.92   0.13   0.28   -1%   0.12   0.58   6%
  Cu (%)   57,986   0.11   0.78   0.12   0.53   -3%   0.12   0.71   -6%
  Ag (g/t)   57,986   10.68   0.67   10.68   0.20   0%   11.06   0.51   -3%
  Fe (%)   57,986   8.06   0.15   8.37   0.12   -4%   8.27   0.11   -3%

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Domain   Grade   No. Blocks   NN   OK   Dif. Rel.
NN_OK(%)
  IDW3   Dif. Rel.
NN_ID3(%)
      Mean   CV   Mean   CV     Mean   CV  
OB12VM   Zn (%)   34,995   0.52   0.46   0.51   0.22   3%   0.51   0.27   2%
  Pb (%)   34,995   0.15   0.70   0.14   0.33   5%   0.15   0.43   2%
  Cu (%)   34,995   0.11   0.82   0.11   0.48   5%   0.11   0.63   -2%
  Ag (g/t)   34,995   29.35   1.17   27.51   0.67   6%   28.69   0.95   2%
  Fe (%)   34,995   9.63   0.52   9.37   0.34   3%   9.98   0.44   -4%
OB14VM   Zn (%)   152,621   1.60   0.92   1.51   0.49   6%   1.56   0.68   2%
  Pb (%)   152,621   0.61   1.09   0.63   0.68   -3%   0.64   0.81   -5%
  Cu (%)   152,621   0.10   1.24   0.09   0.91   8%   0.10   1.03   4%
  Ag (g/t)   152,621   25.50   1.50   25.43   1.10   0%   26.33   1.25   -3%
  Fe (%)   152,621   6.88   0.85   6.81   0.70   1%   6.88   0.79   0%
OB5BVM   Zn (%)   20,936   1.84   0.77   1.87   0.54   -2%   1.86   0.62   -1%
  Pb (%)   20,936   0.25   1.04   0.27   0.52   -9%   0.27   0.65   -9%
  Cu (%)   20,936   0.01   1.25   0.01   0.66   13%   0.01   1.09   2%
  Ag (g/t)   20,936   11.14   1.08   11.53   0.57   -3%   11.94   0.70   -7%
  Fe (%)   20,936   3.20   0.61   3.14   0.44   2%   3.21   0.48   0%
PUCVM   Zn (%)   12,028   0.75   1.18   0.70   1.00   7%   0.70   1.01   7%
  Pb (%)   12,028   0.66   1.03   0.61   0.78   8%   0.61   0.79   7%
  Cu (%)   12,028   0.15   1.07   0.14   0.97   1%   0.14   0.97   1%
  Ag (g/t)   12,028   44.02   0.65   41.50   0.61   6%   41.71   0.61   5%
  Fe (%)   12,028   7.33   0.47   7.23   0.44   1%   7.23   0.44   1%

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Figure 11-33:           Swath Plot: Zn Grade Variation along X, Y, and Z

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Figure 11-34:           Swath Plot: Cu Grade Variation along X, Y, and Z

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Figure 11 35:          Vertical Section Showing Zn Block versus Composite Grades

 

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Figure 11 36:          Vertical Section Showing Cu Block versus Composite Grades 

 

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Figure 11-37:           Plant Versus Resource Model Reconciliation

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11.16 Mineral Resource Reporting

 

The Mineral Resources for the Cerro Lindo underground operation as of December 31, 2020, are summarized in Table 11-1. The Mineral Resource estimate was reported using all the material within resource shapes generated in Deswik software, satisfying minimum mining size, continuity criteria, and using an NSR cut-off value of US$33.56/t for SLS resource shapes and US$49.90/t for C&F resource shapes (Figure 11-38 and Figure 11-39). Cerro Lindo Mineral Resources are in compliance with the S-K 1300 resource definition requirement of “reasonable prospects for economic extraction”.

 

Wireframe models for the underground excavations completed at Cerro Lindo as of May 31, 2020 were prepared to remove the portions of the mineralized zones that had been mined out before the resource and reserve stopes were generated. Mineral Resource and Mineral Reserves estimates were depleted for forecast production from June 1, 2020 to December 31, 2020. After year-end, SLR verified the estimate by reviewing actual mining results for this period of projected mining. Deviations from plan, amounting to approximately 11% less of the 2020 forecast production, were caused by lower production in Q2 2020 due to the COVID-19 pandemic. Production ramped up to pre-pandemic levels in June 2020. The SLR QP is of the opinion that this has had an insignificant impact on the year-end resource and reserve estimates. The sub-blocking functions of the Deswik software package were employed to maximize the accuracy of the mined-out contacts. For the underground excavations, solid models of the stopes, mine development, and drifts were constructed digitally from data collected using an Optech cavity monitoring system and a total station surveying units.

 

Nexa also generated solids for non-recoverable areas (“no possible” solids) due to poor ground conditions and inaccessibility, to remove these zones from the Mineral Resources and Mineral Reserves. SLR considers generating operational and safety constraints to identify, quantify, and remove the tonnes and grades from Mineral Resources and Mineral Reserves to be a good practice. SLR recommends documenting all the data support to define non-recoverable solids and document any changes to these solids.

 

The SLR QP reviewed the resource shapes and is of the opinion that they could be improved. Currently, resource shapes have on average 20% internal dilution, however, there are some areas with resource shapes with more than 30% of internal dilution due to the large dimension of the shape. Internal dilution is particularly high in the shapes at the edges of the orebodies. SLR recommends reviewing the resource shape construction methodology to optimize resource shapes in order to reduce unnecessary internal dilution and improve grades, and possibly generate more shapes that were not built due to the methodology used.

 

SLR also noticed that there is a significant amount of tonnes within blocks above the NSR cut-value that were not included in the Mineral Resources or Mineral Reserves, and are not part of the “no possible” solids. Nexa and SLR reviewed these areas and note that they are mostly skin remnants, however, SLR recommends re-evaluating these zones on an ongoing basis to potentially include part of these tonnes with continuous blocks that have the potential to be recoverable, to generate resource shapes and possibly reserve stopes.

 

SLR also observed a minor overlapping of the resource shapes with areas that were depleted but not surveyed (“no-survey” solids) from the previous model, however, a “no survey” solid was not generated for the updated model and no documentation was provided to support the changes. The overlapping volume is not material as it is less than 1%. Nevertheless, SLR recommends generating a “no survey” solid to account for the mined-out areas that were not surveyed, and document work to support the resultant solid.

 

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In the SLR QP’s opinion, the assumptions, parameters, and methodology used for the Cerro Lindo underground Mineral Resource estimates are appropriate for the style of mineralization and mining methods.

 

The SLR QP is of the opinion that, with consideration of the recommendations summarized in Section 1 and Section 23, any issues relating to all relevant technical and economic factors likely to influence the prospect of economic extraction can be resolved with further work.

 

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Figure 11-38: Plan View of Mineral Resources Inclusive and Exclusive of Mineral Reserves

 

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Figure 11-39: Longitudinal View of Mineral Resources Inclusive and Exclusive of Mineral Reserves

 

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11.17 Comparison to Previous Mineral Resource Estimates

 

A comparison of the current Nexa Mineral Resource estimate, exclusive of Mineral Reserves, to the previous 2019 Mineral Resource estimate is presented in Table 11-24. Overall, the resources have increased significantly. The differences are primarily due to the following changes:

 

New resource shape reporting methodology that includes all the material in each resource shape.

 

Updated “no possible” areas that are excluded from the Mineral Reserves and Mineral Resources, due to poor ground conditions and inaccessibility.

 

Improvement of grade continuity in the model.

 

Extension of the mineralization domains (SPP, SPB, SSM, and VM) based on infill and exploration diamond drilling; particularly, VM as part of the background rock.

 

The addition of new mineralization domains (OB11VM, OB12VM, OB5BVM, OB14VM y PUCVM) as a result of exploration diamond drilling.

 

New classification criteria for SSM and VM.

 

Slightly higher NSR cut-off values.

 

Depletion of material through mining.

 

Slightly lower density values due to the addition of 1,181 density determinations from the 2019-2020 drilling campaign located mostly at the extremity of the mineralization domains.

 

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Table 11-24: Cerro Lindo Comparison of 2020 Versus 2019 Mineral Resources 

Nexa Resources S.A. – Cerro Lindo Mine

 

  Cerro Lindo Mineral Resources - December 31, 2020 Cerro Lindo Mineral Resources - December 31, 2019
    Grade Contained Metal Grade Contained Metal
  Tonnage Zinc Lead Copper Silver Zinc Lead Copper Silver Tonnage Zinc Lead Copper Silver Zinc Lead Copper Silver
Category (Mt) (%) (%) (%) (g/t) (000 t) (000 t) (000 t) (000 oz) (Mt) (%) (%) (%) (g/t) (000 t) (000 t) (000 t) (000 oz)
Measured 4.40 2.00 0.20 0.67 19.61 87.8 8.9 29.4 2,774 3.10 2.58 0.33 0.69 27.87 79.8 10.2 21.4 2,776
Indicated 3.46 1.37 0.25 0.45 24.96 47.3 8.8 15.5 2,776 2.27 1.64 0.28 0.68 29.66 37.4 6.3 15.4 2,167
Total M&I 7.86 1.72 0.22 0.57 21.96 135.1 17.6 44.9 5,550 5.37 2.18 0.31 0.68 28.63 117.2 16.5 36.8 4,943
Inferred 8.71 1.28 0.35 0.33 31.23 111.1 30.6 29.1 8,748 5.14 2.43 0.53 0.53 43.12 125.1 27.1 27.1 7,123

 

 

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12.0 Mineral Reserve Estimates

 

12.1 Summary

 

Table 12-1 summarizes the Mineral Reserve estimate effective as of December 31, 2020.

 

Table 12-1: Summary of Mineral Reserves – December 31, 2020 

Nexa Resources S.A. – Cerro Lindo Mine

 

    Grade Contained Metal
 

Tonnage 

Zinc Lead Copper Silver Zinc Lead Copper Silver  

Category 

(Mt) 

(%) 

(%) 

(%) 

(g/t) 

(000 t) 

(000 t) 

(000 t) 

(000 oz) 

 
Proven 29.37 1.71 0.23 0.60 20.86 501.5 66.1 177.3 19,702  
Probable 22.73 1.08 0.18 0.62 21.58 246.4 40.0 141.8 15,770  
Total 52.10 1.44 0.20 0.61 21.17 747.9 106.1 319.1 35,472  

 

 

Notes:

 

1. The definitions for Mineral Reserves in S-K 1300 were followed for Mineral Reserves which are consistent with CIM (2014) definitions.

2. Mineral Reserves are estimated at NSR cut-off values of US$33.56/t processed SLS and US$49.90/t processed for C&F stoping. A number of incremental stopes (down to US$26.16/t NSR value) are included in the estimate.

3. Mineral Reserves are estimated using average long term metal prices of Zn: US$2,494.90/t (US$1.13/lb); Pb: US$1,956.00/t (US$0.89/lb); Cu: US$6,457.90/t (US$2.93/lb); Ag: US$16.85/oz with all costs in US dollars.

4. A minimum mining width of 5.0 m and 4.0 m was used for SLS stopes and C&F stopes respectively.

5. Bulk density varies depending on mineralization domain.

6. Numbers may not add due to rounding.

7. The Mineral Reserve estimate is reported on a 100% basis. Nexa owns 80.16%.

 

The Mineral Reserves were estimated by Nexa and reviewed by SLR. Measured and Indicated Mineral Resources were used as inputs for conversion into Proven and Probable Mineral Reserves respectively. Mineral Reserves also include unclassified and Inferred blocks in the form of internal dilution and planned dilution.

 

Reserve NSR factors were first added to the resource model. Deswik Stope Optimiser (DSO) was used to generate mining shapes at an NSR cut-off value of US$25/t. A low NSR cut-off value was used to generate the shapes to enable the capture of as much of the mineralization as possible. No planned dilution parameters were considered at this stage. DSO was run separately for each orebody to account for its respective strike and dip direction.

 

The generated shapes were then cut against a grid that represents the general stope size and mining pattern. The cut stopes were then depleted against as-built wireframes. The resulting shapes were interrogated against the block model and the average grades and NSR value were calculated. The shapes were then reviewed and excluded from Mineral Reserve estimates where appropriate.

 

The retained stopes are used to guide the development designs. The development and stope designs are then added to Deswik Scheduler to generate a production schedule. The dilution and extraction factors are applied in the scheduler. Mineral Reserves are reported as diluted and extracted stope and ore development tonnes and grades. These were fully scheduled in an appropriate LOM plan and applied to a discounted cash flow model. The Mineral Reserve estimate has demonstrated viable economic extraction.

 

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Mineral Reserves were estimated by flagging mined-out stope surveys through May 31, 2020 as zero values in the block model. Planned mining to December 31, 2020 was identified and excluded from Mineral Reserve estimates and production schedule. After year-end, SLR verified the estimate by reviewing actual mining results for this period of projected mining. Deviations from plan, amounting to approximately 1% of total Mineral Reserve tonnage, were caused by lower production in Q2 2020 due to the COVID-19 pandemic. Production ramped up to pre-pandemic levels in June 2020. SLR considers that these deviations are not significant to the estimate of Mineral Reserves.

 

The SLR QP is not aware of any risk factors associated with or changes to any aspect of the modifying factors such as mining, metallurgical, infrastructure, permitting, or other relevant factors that could materially affect the Mineral Reserve estimate.

 

12.2 Dilution

 

The dilution factors utilized for the mine design at Cerro Lindo are listed in Table 12-2.

 

Table 12-2:        Mine Dilution Factors

Nexa Resources S.A. – Cerro Lindo Mine

 

Description   Method   Long Term   Former   Source   Short Term
Operational Dilution   Primary ¹   1.0%   5.7%   Historical   5.90%
    Secondary   6.5%   8.10%   Historical   6.10%
    Tertiary   6.5%   8.10%   Historical   3.80%
    C&F   5.0%   5.0%   Historical    
    Pillar- C&F   11.3%   11.3%   Historical    
    Open Stoping   15%   15%   Historical    
Planned Dilution       12%   12%   Historical   15% to 20%

 

The primary stopes have typically lower dilution being within the central portion of the mineralized zone and bounded by the secondary stopes. The current or long term factors are based on new layouts which have proven to be successful. The lower dilution is applied to high grade stopes. Secondary stopes have seen an improvement in the level of dilution as well, and the overall dilution figures are supported by the reconciled production numbers reviewed by SLR. The short term dilution factors are typically higher, as indicated in Table 12-2. While the current dilution numbers are supported by the tonnage and grade reconciliation, an increased level of mining on the fringes of the deposit will, in the SLR QP’s opinion, require some re-design or revised stoping method to maintain acceptable dilution levels. The dilution is assumed to be at zero grade.

 

SLR has reviewed the impacts of changes to the dilution estimate. While increasing dilution could render some reserves below cut-off grade the proportion is relatively low and overall the Mineral Reserves are relatively insensitive to dilution fluctuations.

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12.3 Extraction

 

The extraction (recovery) factors for the stopes are shown in Table 12-3. The new layouts have increased the extraction by one percent in the primary stopes and by five percent in the secondary and tertiary stopes. The increases are justified based on the reconciliation of the planned versus actual stope tonnages.

 

Table 12-3:           Mine Stope Extraction Factors 

Nexa Resources S.A. – Cerro Lindo Mine

 

Method   Long Term   Source   Short Term
  Current   Former    
Primary   85%   86%   Historical   84.40%
Secondary   81%   76%   Historical   84.70%
Tertiary   81%   76%   Historical   76.50%
C&F   90%   90%   Historical    
Pillar- C&F   88%   88%   Historical    

 

While the extraction values appear to be low, they include, in addition to accounting for underbreak and mucking losses (inaccessible due to rough corners and muck hung-up), short term design changes. Stope shapes used in the Mineral Reserve estimation are completed on a regular grid, so that the extraction factor also accounts for skin pillars that are left in place to maintain the integrity of the adjacent backfill. Mineral Reserve tonnage and metal content are affected in direct proportion to variations in extraction.

 

12.4 Net Smelter Return and Cut-off Value

 

An NSR cut-off value is determined using the Mineral Reserve metal prices, metal recoveries, concentrate transport, treatment and refining costs, as well as mine operating costs. The metal prices used for the Mineral Reserves are based on consensus, long term forecasts from banks, financial and other sources.

 

The cut-off value used for the reserves is based on an NSR value (US$/t processed), which can be directly compared to the mine operating costs. The NSR formula is:

 

NSR =  Gross Revenue – Offsite Charges
Tonnes Processed

 

Costs and other parameters used to calculate the NSR cut-off value are shown in Table 12-4. The breakeven NSR cut-off value was estimated to be $33.56/t processed. An incremental cut-off value of $26.16/t is used for certain stopes, for example in the middle of the extraction sequence, where the cost of the development to access the ore has been paid for by adjacent reserves mined. For the sill pillar recovery where a C&F conventional method is used, a higher NSR cut-off value of $49.90/t is used.

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Table 12-4:             NSR Data 

Nexa Resources S.A. – Cerro Lindo Mine

 

Item   Units   SLS   C&F
Net Metallurgical Recovery *        
Zn   %   88.13   88.13
Pb   %   68.58   68.58
Cu   %   86.30   86.30
Ag   %   68.78   68.78
Cu Concentrate Payable %            
Cu   %   96.7   96.7
Ag   %   90.0   90.0
Pb Concentrate Payable %            
Pb   %   95.0   95.0
Ag   %   95.0   95.0
Zn Concentrate Payable %            
Zn   %   95.8   95.8
Ag   %   70.0   70.0
Metal Prices            
Zn   US$/lb   1.13   1.13
Pb   US$/lb   0.89   0.89
Cu   US$/lb   2.93   2.93
Ag   US$/oz   16.85   16.85
Charges            
Logistics and TC            
Zn Concentrate   US$/t conc   321.0   321.0
Pb Concentrate   US$/t conc   251.0   251.0
Cu Concentrate   US$/t conc   245.0   245.0
Integrated Zn            
Conversion Cost   US$/t Zn prod   447.0   447.0
Premium   US$/t Zn Prod   217.0   217.0
Refining Cost            
Ag in Pb conc   US$/oz   1.00   1.01
Ag in Cu conc   US$/oz   0.50   0.51
             
Operating Costs            
Mining   US$/t proc.   21.00   37.34
Processing + Maintenance   US$/t proc.   10.42   10.42
G&A   US$/t proc.   2.14   2.14
Total   US$/t proc.   33.56   49.90
* Based on LOM average metal grades        

Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
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Nexa reviewed supply and demand projections for zinc, lead, and copper, as well as consensus long term (ten year) metal price forecasts. SLR verified that Nexa’s selected metal prices for estimating Mineral Reserves are in line with independent forecasts from banks and other lenders.

 

The average NSR factors are calculated using the LOM revenue contribution from each metal net of off-site costs and factors, divided by the reserve grade for that metal, and are indicative of the relative contribution of each metal unit to the economics of the Mine. For most metals, a variable recovery (as a function of head grade) was used, and therefore the average NSR factors should not be applied to head grades without considering the head grade versus recovery relationship. Therefore, the NSR factors are variable by head grade, with NSR factors summarized in Table 12-5. The grade-recovery relationship for each metal based on recent operating performance are presented in Figure 12-1, Figure 12-2, and Figure 12-3.

 

Table 12-5:              Average NSR Factors 

Nexa Resources S.A. – Cerro Lindo Mine

 

Metal   Unit   Value
Zn   US$/%   17.49
Pb   US$/%   11.86
Cu   US$/%   47.50
Ag   US$/oz   10.89

 

 

Figure 12-1: Zinc Recovery

Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
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Figure 12-2: Lead Recovery

 

 

Figure 12-3: Copper Recovery

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13.0 Mining Methods

 

13.1 Background

 

Cerro Lindo has been operating since 2007, with production rates of approximately 7 Mtpa in the recent years. The mine is mechanized, using rubber-tired equipment for all development and production operations. Mining is carried out in ten separate orebodies, using bulk longhole stoping methods, with up to 30 m high stopes, in a primary, secondary, and tertiary sequence. Stopes are backfilled with a low-cement content paste fill made from flotation tailings in the surface paste plant and distributed to the underground via two vacuum filter trains.

 

The highest operating level is the 1970 m level, the lowest operating level is the 1550 m level, and the ultimate bottom level is planned to be the 1490 m level.

 

A longitudinal section through the mine is presented as Figure 13-1.

 

The mine is accessed through fifteen portals that service adits, drifts, and declines. The main ore flow is directed via the grizzly installations on the 1830 m level that feed the jaw crusher located on the 1820 m level. From the crusher discharge, the ore flows up to the surface stockpile areas via an inclined conveyor and out at the 1940 m level from where it continues to flow to the plant via inclined surface conveyors.

 

A simplified plan view of the 1820 m level is shown in Figure 13-2. It shows existing and planned development in ore, mined out and planned stoping blocks, portals, and the conveyor incline.

Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
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Figure 13-1: Longitudinal Section of the Mine

Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
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Figure 13-2: Simplified Plan View of the 1820 m Level

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13.2 Mine Design

 

The mine design includes access via 5.0 m by 4.5 m ramps driven at various gradients to access the stope areas and other infrastructure (sumps, electrical substations, refuge stations, storage areas, etc.). A fleet of 35 t and 52 t haul trucks operated by contractors move the muck to the grizzlies located on the 1830 m level. The ore is crushed at this level and conveyed to the surface stockpiles. The underground mine design is presented in Figure 13-3.

Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
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Figure 13-3: Cerro Lindo Underground Mine Design

Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
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13.3 Mine Method

 

The stoping methods employed at Cerro Lindo include the bulk Sublevel Longhole Stoping (SLS) method, which accounts for the majority of the production, and the Cut and Fill (C&F) method, utilized where necessary such as for the mining of sill pillars which require a more conventional method for economic extraction. The SLS stope dimensions are typically 20 m to 30 m in height by 25 m long and vary in width. Dimensions can vary given the orebody geometry or local geotechnical conditions which necessitate extra care in keeping stopes of a size to permit effective ground control and stoping productivities.

 

SLR considers the mining methods and stope dimensions appropriate for the style of mineralization at Cerro Lindo. SLS has been extensively used at the mine and the current mine designs follow a similar approach. SLR also notes that there is on-going investigations into using C&F mining methods to extract pillars where possible.

 

The SLS method can vary with production drilling being completed in a fan pattern using downward drilling or uppers drilling as illustrated in Figure 13-4. The production drill holes vary in size from 102 mm in diameter for the downward drilling to 76 mm in diameter for uppers drilling to optimize stoping results in terms of size of fragmentation and overall stoping productivity. The stope design includes detailed support plans, production drill plans with optimized burden and spacing, and detailed loading and blasting plans to provide for the best stoping results. Where effective, for example, electronic delays are used in the blast timing which provides for very precise timing leading to less swell space requirement and improved fragmentation. This enables a reduction in secondary breaking resulting in improved operating costs.

 

The stope designs are carried out and are detailed in a document titled “Autorización de Trabajo” (Work Authorization). This document outlines all aspects of the stope designs including access ways, refuge areas, loading areas to be used, and geomechanical risks (high, medium, or low), drilling and blasting layouts, specific geology of the area, ground support design, based on geotechnical assessment (using finite element models), ventilation requirements (air quantities), backfill requirements (cement content, backfill lines, backfill rates), and a stope risk analysis table outlining the risks identified and the mitigation measures to be taken to address and eliminate these risks. In the SLR QP’s opinion, these documents form the basis of a robust approach to the mine operations and meet or exceed industry best practices.

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Figure 13-4: Production Drilling Layout

Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
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13.4

Geotechnical Considerations

 

Independent geotechnical assessments were commissioned for the Cerro Lindo deposit, including by AMEC in 2013 and SRK in 2016 and 2018.

 

SRK completed a geomechanical 3D modelling exercise and evaluation of the overall stability conditions within the mine. These assessments provide recommended design standards for development and production stope openings, backfill strength requirements, maximum stope dimensions, and guidance for stope sequencing.

 

13.4.1 Geotechnical Overview

 

The main lithological units have been described and modelled with acceptable detail to support geotechnical characterization and hazard evaluation related to mining activities. As related to the mining method (SLS) employed at the time of the assessment, rock mass conditions are well understood and appropriate for the current mining depths, the rock reinforcement types, and geotechnical input into the mine production and development.

 

The geotechnical mapping and data analysis protocols include industry-standard practices such as detailed descriptions of the various structural domains and their characteristics. This work is based on field mapping, geological modelling, and limited geotechnical core drilling.

 

Geotechnical characterization is a continuous proactive process as new mining areas are accessed.

 

SRK completed a 3D numerical model in 2017 using the FLAC3DTM 5.01 software (Itasca Consulting Group), with the main objective of evaluating the global stability of the mine and the actual and the long term conditions. This model permits evaluation of the rock mass response in terms of stope and mine workings stability. Nexa carried out in-situ stress testing in 2013 and 2014 to aid in the design of the mining sequence.

 

The main objectives of the numerical modelling include the following:

 

Evaluate the global stability of the mine, the actual conditions, and a long term mine plan.

 

Determine the effects of mine induced stresses on the mine infrastructure in future.

 

Evaluate the stability of the stopes and assess potential problem areas in the mine.

 

Evaluate the areas of potential subsidence on surface and potential impact on surface infrastructure.

 

To obtain design data, geotechnical work included logging of drill holes (35) to assess RQD values, establishing geomechanical stations at underground locations (37 stations) in various lithological units, and determining the Rock Mass Rating (RMR), the Modified Rock Quality Index (Q’), and physical properties of the lithological units including, density, porosity and absorption. Measurements of the number of joints, the joint roughness number, and joint alternation number are used to determine the stability number N’. The stability number can be plotted on a stability chart against the stope hydraulic radius to assess if the surface considered is in a stable, transition, or caving zone of the rock mass. This in turn enables assessing the required level of support to provide the required stability.

 

In 2019 Nexa carried out laboratory testing to determine the mechanical properties such as uniaxial compressive strength, triaxial compressive strength, indirect tensile strength, elastic moduli of intact rock, and pulse velocities and ultrasonic elastic constants. All testing was completed using norms such as the ASTM (American Society of Testing and Materials), IRMS (International Rock Mechanics Society), and AAMR (American Association of Rock Mechanics) in accordance with best practices. The most recent laboratory testing was carried out in 2019 by Geomecánica Latina S.A., with offices in Peru, Bolivia, and Chile.

Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
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The various factors for the lithologies are shown inTable 13-1.

 

Table 13-1:          Design Factors for Lithologies 

Nexa Resources S.A. – Cerro Lindo Mine

 

Type   Acronym   RQD   Jn   Jr   Ja   Q’(mean)   RMR89
Primary Pyritic Sulphides   SPP   66   7.84   1.62   2.11   6.46   60
Primary Baritic Sulphides   SPB   80   5.41   1.84   1.92   14.17   66
Semi Massive Sulphides   SSM   80   6.07   1.82   2.72   8.82   67
Andesitic Volcanics   DIQUE   71   6.92   1.64   3.23   5.21   67
Felsic Volcanics   VOLCANIC   75   6.72   1.58   3.23   5.46   67
Volcanics waste   ENCLAVE   74   6.9   1.59   3.28   5.20   66
Leached/Oxidized Sulphides   SLB/SOB/SOP   49   10.82   1.74   3.98   1.98   46
Faults   Faults   27   14.05   1.24   4.76   0.50   37

 

The stability and rock quality factors for the Cerro Lindo lithologies are shown in Figure 13-5. Note that the stability number N’ is based on the standard stope dimensions of 30 m high by 19 m long by 13.5 m wide.

 

 

Figure 13-5: Stability and Rock Quality Indices

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13.4.2 Geomechanics, Ground Support

 

The geomechanical classification and ground support standards were developed by Nexa staff and the geomechanical classifications are shown inTable 13-2.

 

Table 13-2:                     Geomechanical Classification

Nexa Resources S.A. – Cerro Lindo Mine

 

Classification   RMR   TYPE
Good   61-80   II
Regular A   51-60   III A
Regular B   41-50   III B
Poor A   31-40   IV A
Poor B   21-30   IV B
Very Poor   <20   V

 

The ground support standards developed by Nexa staff are shown in Figure 13-6 which cover the various conditions encountered throughout the underground mine. The bolting pattern is shown for various conditions and the type and length of bolt or rebar to be used. Shotcrete is also used as required with a typical sprayed thickness of five centimetres. Where necessary, cable bolts, typically six to seven metres in length, are also used. In the long life areas, such as the main crusher room, heavier support is provided with input from specialized people.

 

Figure 13-7 shows an example of a finite element modelling longitudinal section used to assess the safety factors for the back and walls of the T320B-1880 stope. From this analysis and use of plans and sections of the structural geology, a stability chart can be developed providing an assessment of the equivalent length of slough (ELOS) from the stope walls for dilution estimation, the ground support methods (bolts, mesh, cable bolts, shotcrete) required to provide the support based on the RMR values, and the backfill strength required (cement content) to provide the design stability.

 

For this case, the stability chart has indicated that the stope, with dimensions of 18 m high by 18 m long by 12 m wide, is located in the transition zone, between the stability zones that indicate ground support is required and not required. The anticipated ELOS is between one to two metres. The paste fill adjacent to the stope has a strength of 0.46 MPa (cement content of 3%), while for a safety factor of 1.3 on the stability modelling, the required strength is 0.35 MPa. For the stope back (roof), the model predicts a safety factor of 0.95 due to rock class IVA at the contact zone of volcanic rock. Cable bolting is recommended at the intersection of the drift and crosscut. The ten metre sill pillar should be monitored by scanning to verify the stability of the pillar.

 

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Figure 13-6: Ground Support Standards 

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Figure 13-7: Finite Element Model for T320-1880 Stope Safety Factor Assessment 

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13.5 Hydrogeological Considerations

 

The Cerro Lindo is a relatively dry mine and does not produce significant quantities of water. Exploration drilling to date has not intersected any water bearing structures that could introduce major inflows in the mine workings. The only pumping requirement is to remove drilling water from the active workings. The water is collected, treated, and recycled for use in the operation.

 

13.6 Life of Mine Plan

 

The life of mine (LOM) plan is shown in Table 13-3. The production from 2021 through 2029 will include approximately 52.1 Mt with average grades of 21 g/t Ag, 0.61% Cu, 0.20% Pb, and 1.44% Zn over the LOM period. This will result in the production of recovered metal including 35.5 Moz of silver, 319.1 kt of copper, 106.1 kt of lead, and 747.9 kt of zinc.

 

The LOM production profile is shown in Figure 13-8. The figure indicates a significant decrease in production starting in 2025 due to increased mining on the fringes of the deposit requiring a higher level of preparation and consequently impacting the mine throughput capability. More importantly, the current LOM plan includes mining stopes in proximity to the underground main crushing station which will effectively negate use of the crusher and, as a result, require haulage of ore to surface and additional truck haulage fleet.

 

 

Figure 13-8: LOM Production Profile

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Table 13-3:                 Life of Mine Plan

Nexa Resources S.A. – Cerro Lindo Mine

 

Description   Units   Total   2021   2022   2023   2024   2025   2026   2027   2028   2029
Production   t (000)   52,101   7,000   7,000   6,500   6,500   5,000   5,000   5,000   5,000   5,101
Production Rate   tpd   17,843   19,178   19,178   17,808   17,808   13,699   13,699   13,699   13,699   13,976
Ag Grade   g/t   21.15   18.97   22.08   24.26   23.02   27.99   18.97   17.42   19.60   17.73
Cu Grade   %   0.61%   0.44%   0.48%   0.52%   0.59%   0.75%   0.68%   0.73%   0.73%   0.75%
Pb Grade   %   0.20%   0.23%   0.25%   0.26%   0.22%   0.28%   0.18%   0.13%   0.13%   0.10%
Zn Grade   %   1.44%   1.77%   1.56%   1.50%   1.38%   1.70%   1.51%   1.34%   1.12%   0.87%
Contained Ag   oz (000)   35,472   4,273   4,974   5,042   4,807   4,487   3,025   2,804   3,134   2,926
Contained Cu   tonnes   319,137   31,023   33,609   33,643   38,349   37,479   34,000   36,261   36,661   38,113
Contained Pb   tonnes   106,140   15,924   17,704   17,218   14,514   14,026   8,898   6,322   6,455   5,079
Contained Zn   tonnes   747,899   123,900   109,030   97,500   89,600   85,000   75,461   67,224   55,967   44,217

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13.7 Infrastructure

 

This section covers the underground infrastructure, with the main surface infrastructure described in Section 15 Project Infrastructure.

 

13.7.1 Mine Access

 

Cerro Lindo is accessed by means of multiple ramps due to the high number of deposits that make up the mine operations. The ramps are driven at various gradients to attain the required operating level throughout the various deposits. Ramp dimensions are typically five metres by five metres, which corresponds to the dimensions necessary to meet regulations for equipment clearances, ventilation requirements, and adequate space for installation of services carried via the ramp accesses. There are three main ramps that provide access to the lower levels of the mine and these are being deepened to continue accessing lower levels. There are also local ramps that provide access to the operating stopes and stopes being developed and prepared for production.

 

13.7.2 Ventilation

 

The mine ventilation circuit at Cerro Lindo is extensive, consisting of portals, main fans, and interconnecting ramps and raises.

 

The ventilation circuits are typically separated by orebody. A total of 2.37 million cfm enters the mine through 12 portals and raises and exhaust though six raises. The ventilation system is powered by 19 main fans which are installed on the exhaust circuits and several booster fans. The main fans draw exhaust air from the various mining areas and direct it to dedicated exhaust levels or raises.

 

Figure 13-9 illustrates the ventilation circuit for OB1.

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Figure 13-9: Cerro Lindo Ventilation Circuit Schematic

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13.7.3 Material Handling

 

Production muck is hauled from the stope areas to a grizzly located on the 1830 m level, with the grizzly product feeding a jaw crusher located on the 1820 m level. A feeder then delivers the crusher ore to a main conveyor used to convey ore from the 1820 level loading chute up to surface via the 1940 m level portal to the stockpiles. The ore is comingled and not segregated in separate stockpiles.

 

Waste material from the mine development is dumped into available stopes or, if required, hauled to surface.

 

13.7.4 Power

 

The underground mine is serviced by a power reticulation system that provides approximately 7 MW. The main feed to the underground is at 10 kV and feed to substations and reduced to 480 V on the secondary to feed the mining equipment, mine pumps, mine ventilation fans, and auxiliary fans. The mine has backup generator to support the main ventilation system.

 

13.7.5 Service Water

 

Service water is very important at Cerro Lindo, which requires recycling and reuse at the maximum possible rate. Service water is used mainly for drilling purposes, cooling, dust control, and shotcrete/concrete requirements. The water is provided from a central plant-wide source and distributed to the underground via a system of pipelines to the working areas. The water is sourced from a desalination plant at the ocean and pumped approximately 180 km via three pump stations to a final elevation of 2,100 MASL at the mine site.

 

13.7.6 Dewatering

 

The mine generates very little water from geological sources. The sumps located on the lower levels in active mine areas feed the two pumping stations located on the 1680 m level via 100 mm diameter pipelines. From the two pump stations water is pumped up to the 1820 m level pumping station via 100 mm and 150 mm diameter lines and further on to the reservoir located on the 1970 m level and out to the surface storage area. The mine utilizes an effluent treatment plant that consists of a basic system of water clarification using three contingency ponds.

 

13.7.7 Backfill

 

Paste backfill is used at Cerro Lindo and is prepared in the paste plant located on surface near the exhaust portals. The plant is supplied with mill tailings by pipeline from the plant. The plant operates two vacuum filter trains capable of supplying 300 t/h of filter cake to the paste mixers. The nominal binder is 3% but can vary as required to achieve the desired strength. The paste is pumped to the underground via the 1970 m level exhaust portals with pipes laid on the floor of the drifts for most of the distance. The total paste delivery is designed at 5,000 m³/d, with the plant operating at 95% availability and capable of meeting the demand. When the stopes are distant from the paste fill source, additional water is used to enable transport via the pipeline, however, this can result in paste fill of lower quality. SLR recommends that for such conditions a trade-off study be carried out to assess the use of cemented rock fill (CRF) which may be more effective in providing the required strength.

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13.7.8 Compressed Air

 

Almost all drilling equipment in the mine is electric over hydraulic and equipped with on-board air compressors. A compressed air reticulation system delivers compressed air from surface for uses such as construction, ground support, etc.

 

13.7.9 Maintenance Facilities

 

There are two service level shops underground operated by contractors Caterpillar and Atlas Copco. These shops are equipped for light maintenance and preventive maintenance services, while equipment requiring major repairs and services is taken to the surface shop facilities. Contractors providing support for the mine maintain their own service on surface and do not use the underground facilities.

 

13.7.10 Communications

 

The underground mine is equipped with a leaky-feeder radio system providing for effective communications to all areas of the mine and hard-wired telephones to select locations. The mine is serviced by an underground communications centre, which is operating 24 hours per day. Mine rescue teams are available in case of emergency situations.

 

Nexa should consider upgrading the mine’s underground data-communications capabilities by replacing the present leaky-feeder system with a Wi-Fi fibre-optic network or a 4G-LTE cellular network. An upgraded communications system will permit implementing centralized control and monitoring of underground operations from a control room on surface. These centralized functions can include real-time tracking of personnel and equipment, telemetry, ventilation-on-demand, and closed-circuit television, among other applications.

 

With a wireless communications system, Nexa should consider implementing automated and/or tele-remote technology to operate equipment from control stations on surface. The technology can be used for mucking stopes, mucking development headings, production drilling, crushing, and operating rockbreakers, among other applications. A significant benefit is that it allows many mining operations to continue during otherwise non-productive periods, including lunch breaks, shift changes, blasting times, and ventilating smoke.

 

13.8 Mine Equipment

 

The list of mining equipment is provided in Table 13-4. There are multiple contractors operating in various capacities at Cerro Lindo and the equipment list shown can vary as contractor work programs vary over time.

 

Table 13-4:                Mine Equipment List 

Nexa Resources S.A. – Cerro Lindo Mine

 

Description   Nexa   Tumi   Incimmet   Aesa   American   Dinet   Total
Jumbos   2       2   7           11
Production Drills   6       2               8
Bolters   3       2   5           10
Scalers/Breakers   6       2   4           12

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Description   Nexa   Tumi   Incimmet   Aesa   American   Dinet   Total
Scissor Lifts   0           5           5
Scoops 9Yd   14           2           16
Scoops 6Yd           3   5           8
Conventional Trucks 35t                   16   26   42
Conventional Trucks 52t                       26   26
Boom Truck   3           5           8
Excavator   6               4       10
Raisebore       6                   6
Forklift           4               4
Transmixer           1               1
ANFO Truck               6           6
Fuel Truck               1           1
Dozers                   3       3
Front End Loaders                   2       2
Grader                   1       1
Compactor                   2       2
Total   40   6   16   40   28   52   182

 

The mine equipment performance criteria and productivities are shown in Table 13-5. The required number of crews is also shown and estimated from the productivity levels and production requirements.

 

Table 13-5:           Equipment Performance Criteria and Productivities

Nexa Resources S.A. – Cerro Lindo Mine

 

Equipment   No. Units   Distribution (Contract/Nexa)   Availability %   Utilization %   Productivity (avg.)   Units   Crews (avg.)
Bolters   8   2/2   83   46   39   m/h   6.6
Scalers   11   7/4   71   46   31   m²/h   7.8
Trucks 35t   42   42/0   73   78   34   t/h   10.7
Trucks 52t   26   26/0   65   71   41   t/h   16.9
Jumbo Drills   9   7/2   83   56   111   m/h   7.5
LHDs   22   11/11   83   66   120   t/h   12.8
Simba DTH/ITH   6   0/6   75   54   24   m/h   4.5
Raptor LH   4   0/4   79   44   21   m/h   3.2

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13.9 Manpower

 

The workforce of Cerro Lindo consists of company personnel and contractors. The Nexa personnel and contractor lists for mining operations are presented in Table 13-6 and Table 13-7 respectively. The number of Nexa employees required for mining operations are not expected to change significantly for the foreseeable future. The number of contractors varies month to month depending on labour requirements at the mine site.

 

The production is carried out by the company mine personnel, while contractors carry out the development advances and haulage. Operators and technical staff work a 14 x 7 shift cycle consisting of seven days of dayshift, seven days of nightshift, and seven days off. General staff work on a 5 x 2 shift cycle.

 

Table 13-6:          Nexa Mine Personnel 

Nexa Resources S.A. – Cerro Lindo Mine

 

Area   Managers   General Staff   Operators & Technical Staff   Total
Geology and Exploration   1   9   15   25
Mine   1   29   206   236
Projects   1   7       8
Technical Services   1   24   32   57
Total   5   85   344   434

 

Table 13-7: Mine Contractor List 

Nexa Resources S.A. – Cerro Lindo Mine

 

Contractor   Area   Shift   Number
Explosupport S.A.C.   Exploration   14 x 7   1
Certimin S.A.   Geology   14 x 7   17
Explomin Del Peru S.A.   Geology   14 x 7   139
Transportes San Alejandro S.A.C.   Logistics   14 x 7
6 x 1
  36
Administracion De Empresas S.A.C.   Mine   14 x 7   390
American Renta Car S.A.C.   Mine   14 x 7   53
Dinet S.A.   Mine   14 x 7   267
Exsa S.A.   Mine   14 x 7   57
Incimmet S.A.   Mine   14 x 7   298
Tumi Contratistas Mineros S.A.C.   Mine   14 x 7   66
Union De Concreteras S.A.   Mine   14 x 7   126
Total           1,450

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14.0 Processing and Recovery Methods

 

The Cerro Lindo processing plant is located on a ridge adjacent to the Mine, situated at an altitude of 2,100 MASL to 2,200 MASL. The processing plant commenced operations in 2007 with a processing capacity of 5,000 tpd, however, it has since been expanded to a name-plate capacity of 21,000 tpd. Processing consists of conventional crushing, grinding, and flotation to produce separate copper, lead, and zinc concentrates. Tailings are thickened and filtered for use as backfill or trucked to the dry stack tailings storage facility.

 

14.1 Process Description

 

The Cerro Lindo processing plant layout is shown in Figure 14-1 and a simplified process flowsheet is shown in Figure 14-2.

 

14.1.1 Crushing

 

Crushing is carried out in three stages with the first stage occurring underground, where a primary jaw crusher, fed via a stationary grizzly, crushes ore to less than 100 mm. Crushed ore is conveyed to the coarse ore stockpiles located at the processing plant. When the primary crusher requires maintenance, ore is trucked directly to surface where it is stockpiled prior to being crushed in a mobile primary crusher, which discharges onto the coarse ore stockpile feed conveyor.

 

Coarse ore is reclaimed from the stockpile and fed to two parallel crushing circuits, each consisting of secondary and tertiary crushing. Reclaimed ore is screened, with the oversize reporting to the secondary crushers, while the undersize is directed to the fine ore bins. Secondary crusher product is screened, with the screen oversize reporting to the tertiary crushers and the undersize being directed to the fine ore bins. The tertiary crushers are in closed circuit with the tertiary screens, with the screen undersize directed to the fine ore bins. Ore is crushed to 80% passing (P80) 4 mm, and the two fine ore bins provide approximately 16 hours of storage capacity.

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Figure 14-1: Cerro Lindo Process Plant Layout 

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Figure 14-2: Simplified Process Flowsheet

  

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14.1.2 Grinding

 

Fine ore is fed from the fine ore bins to two parallel ball mill circuits, each in closed circuit with high frequency classifying screens, at a rate of approximately 900 tph. Each grinding circuit also includes flash flotation, producing bulk (copper and lead) concentrate. The first grinding circuit is the original single-stage ball mill circuit installed in 2007 and capable of processing 5,000 tpd, while the second circuit, consisting of two identically sized ball mills in series, can process approximately 15,000 tpd. Grind size for the circuits is P80 150 µm to 170 µm.

 

14.1.3 Flotation

 

Flotation consists of bulk rougher and scavenger flotation to produce a copper-lead concentrate, which is then cleaned and combined with the flash flotation bulk concentrate prior to being separated into copper and lead concentrates. The bulk flotation tails form the feed to zinc rougher and scavenger flotation to produce a zinc concentrate, which is then cleaned. The three concentrates are thickened and filtered, and then deposited into dedicated concrete storage bunkers.

 

Concentrate is reclaimed by front-end loader and each bucket is sampled before being loaded into trucks. The trucks are weighed on a weigh bridge adjacent to the concentrate handling area before being despatched to the Port of Callao (copper and lead concentrates) or Nexa’s Cajamarquilla refinery (zinc concentrate) near Lima, Peru. Concentrate is despatched during the night shift with an average of 32 trucks per night, each carrying approximately 35 wet tonnes of concentrate.

 

14.1.4 Tailings

 

Final tailings consist of zinc scavenger tails. Tailings are directed to the tailings thickener, and the thickened underflow is divided, with a portion going to the two paste backfill plants, and the remainder going to the dry stack tailings filtration plant. The ratio between tailings to paste backfill and dry stack tailings is approximately 50:50.

 

The tailings filtration plant and paste backfill plants are located between the dry stack TSFs to the south of the concentrator. Horizontal belt filters are used to reduce the moisture of the tailings to approximately 12%. Dry stack tailings are discharged onto a stockpile, which is reclaimed by front-end loader and trucks for subsequent placement, grading, and compaction on one of the two dry stack TSFs. Cement and fly-ash are added to the paste backfill tailings filter cake producing a paste of approximately 79% solids. This is pumped underground by high-pressure positive displacement pumps.

 

A concrete spillage containment pond with a capacity of 10,000 m3 is located below the plant platform and tailings thickeners, providing emergency containment if needed.

 

As mining has progressed, the pumping distance of the paste has increased, leading to limitations in the amount of paste that can be pumped to the furthest points in the Mine, in addition to placing strain on the pumping and piping system. This in turn means that dry stack tailings filtration is fully utilized. Any breakdowns in the paste backfill system therefore result in throughput reductions in the processing plant, as there is no tailings surge capacity other than limited space in the tailings thickener. Mitigating steps will be necessary to ensure that paste backfill system limitations do not become significant processing rate constraints in the future. Nexa plans to install an additional belt filter for dry stack tailings filtration, which will help to minimize the effect on processing plant throughput in the case where the paste backfill system is down.

 

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14.1.5 Concentrate Quality

 

The Cerro Lindo concentrates contain low concentrations of deleterious elements and higher than average concentrations of the primary metals. The lead and zinc concentrates are clean and do not currently incur penalty charges. Due to the combined lead and zinc content of the copper concentrate (approximately 4.8% to 5.6%), however, the copper concentrate attracts a small penalty of approximately US$2.00/t.

 

14.1.6 Process Water

 

Water is supplied from a reverse osmosis desalination plant located on the coast capable of producing 60 L/s and is pumped 60 km to the Mine site. This is sufficient to supply the requirements for make-up water and potable water (treated at the Mine site). Most of the process water requirement is recovered from tailings thickening and filtration and is returned to the three 3,600 m3 water storage tanks. Approximately 90% of total tailings water is recovered and recycled to the Cerro Lindo processing plant as process water.

 

14.1.7 Process Consumables and Power

 

The main process consumables include steel grinding balls, sodium cyanide, lime, and various flotation reagents. No significant changes to the feed ore, process, or capacity of the processing plant are anticipated, and therefore unit consumption of these materials is expected to remain similar to historical consumption rates. The process plant electrical energy requirement is approximately 25 MW, which is supplied from the national grid.

 

14.1.8 Manpower

 

The processing plant personnel comprises management and supervisory staff, including metallurgical personnel, and operators, totalling 108 as well as contractors amounting to 42. The processing plant personnel and contractors are presented in Table 18-3 and Table 18-4. These numbers are not anticipated to change significantly in the foreseeable future. Maintenance personnel and contractors, numbering 101 and 399 respectively, have been included in Table 18-3 and Table 18-4.

 

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15.0 Infrastructure

 

A surface plan showing the mine site infrastructure is provided in Figure 15-1. The in-situ and operating infrastructure at Cerro Lindo includes the following:

 

An underground mine accessed by 15 portals.

 

An underground crusher and conveyance system to surface.

 

Surface ore stockpiles and waste rock dumps.

 

A 21,000 tpd processing plant.

 

Two dry-stack TSFs.

 

Main site power supply.

 

Site access roads.

 

Mine shops, offices, warehouse facilities.

 

Mine camps facilities.

 

15.1 Site Access

 

Access to the mine site is via paved highway to Chincha (180 km from Lima), followed by a 60 km unpaved road. The unpaved road covers a significant gain in elevation with several narrow sections that restrict speeds for heavy haulage. Nexa maintains rest stops at wide areas and enforces safe speed limits on employees and contractors.

 

Despite the low speed achievable on the road to the mine, the relatively short distance to Chincha represents a logistical advantage for the Cerro Lindo Mine, in comparison with many Peruvian operations.

 

15.2 Power Supply

 

Power to the mine is supplied via the National Grid by two independent tied-in systems for redundancy at 220kV, namely the Chilca Independence 220kV, through a branch to the Desert substation. The substation has a twin transformer capacity of 6.66-8.33 MVA (ONAN-ONAF), 220/60/22.9 kV, and two transmission lines provide power to the mine site substation and desalination plant and pumping station plant located at Jahuay. Secondary substations on site serve to transform the distribution voltage 10kV to the 480V to 120V for mine equipment.

 

The site power breakdown by area is:

 

Mine 7 MW

 

Desalination and pumping 4 MW

 

Plant 25MW (28kWh/t)

 

Camp 0.50 MW

 

The overall site demand to sustain a production rate of 20,800 tpd is approximately 36.5 MW which is just adequate, however, the system can be increased to 50 MW at an estimated cost of approximately $15 million.

 

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15.3 Water Supply

 

There is no fresh water withdrawal from natural water bodies at the mine site, and the mine obtains very little water from the underground mine workings. Approximately 40% of total demand is extracted from five local groundwater wells/boreholes. The remaining 60% of industrial fresh water is supplied from a desalination plant located on the coast.

 

The pumping system from the desalination plant is divided into three stages to transport the water approximately 45 km to an elevation of 2,200 m. Three pump stations are located along the six-inch pipeline route from the desalination plant to the mine site.

 

Service water is primarily used underground for drilling water, cooling, dust control, and concrete/shotcrete service. Service water is provided from a central plant-wide source and distributed underground via a system of pipelines to all working areas. Service water is collected and pumped to the surface where it is treated for re-use.

 

15.4 Site Buildings

 

Site facilities are distributed along the valley below the concentrator, where terrain permits. Facilities include offices, separate camps for contractors, hourly employees, and staff, warehousing and storage areas, maintenance shops, and the paste fill plant. Fuel storage is located on surface, with underground equipment fueled by service trucks.

 

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Figure 15-1: Surface Plan of Infrastructure

 

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15.5 Mine Waste Management

 

15.5.1 Tailings Management

 

Tailings produced in the process plant are thickened and piped to two possible streams. Approximately 50% of the tailings are further dewatered to 84% solids, mixed with cement and used as paste backfill in the underground workings. The remaining 50% of tailings are thickened separately to a solids content of 88%, loaded onto trucks, and dumped on top of the tailings dry stacks Pahuaypite 1 and 2. Once on the stacks the tailings are allowed to dry for three to four days to reduce their moisture content to 6% to 7%; the tailings are then spread in lifts of 300 mm and compacted to 95% standard proctor maximum dry density. The locations of the dry stacks are illustrated in Figure 15-2.

 

As of May 2020, Pahuaypite 1 has accumulated 6.2 Mm3 of tailings of the total design capacity of 6.3 Mm3, with less than 0.1 Mm3 capacity remaining. Pahuaypite 2 has accumulated 5.6 Mm3 of tailings of 11.0 Mm3, with 5.4 Mm3 capacity remaining. A total of 5.5 Mm3 of tailings capacity remains within the existing design of the surface tailings dry stack, which provides an estimated 4.9 years of tailings storage.

 

It is noted that approval for 10% expansion of the Pahuaypite 1 tailings dry-stack storage capacity has been granted by the authorities. A similar plan is in place for 10% expansion of the Pahuaypite 2 tailings dry-stack storage capacity. The design studies to support the expansion of Pahuaypite 2 are underway. This 10% expansion is included in the capacities given in the previous paragraph. Further plans for expanded tailings storage should be explored to support any future mine plan changes.

 

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Figure 15-2: Mine Site Layout and Waste Management Areas

 

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15.5.2 Tailings Storage Facility

 

Tailings from the mine are stored in two dry-stack deposits, Pahuaypite 1 and 2. These dry stacks are each equipped with a starter dam at the toe of the facility, a foundation drain that runs through the base of the valley(s) under the facility, an intermediate dike or platform to increase the initial working area, and a geomembrane lined water management pond downstream. The foundation drains from the dry stacks continue under the starter dams and report to their respective water management ponds at the base of the facility. The water management ponds downstream of Pahuaypite 1 and 2 were both designed with emergency spillways to safely convey the probable maximum precipitation. However, the emergency spillway for the Pahuaypite 2 water management pond, which is downstream of both tailings dry stacks and the Pahuaypite 1 pond, has been removed to allow for the construction of a new waste rock dump downstream of the pond. According to Ausenco (2017), the tailings dry stacks are classified as “significant” hazard classification according to the Canadian Dam Association (CDA) (2013).

 

The tailings dry stacks are mostly comprised of filtered tailings which are air dried on the working surface of the stack, spread in lifts of approximately 300 mm thickness, and compacted to 95% standard proctor dry density. Quality control data for the compaction and moisture content of the tailings is regularly taken and satisfies the design.

 

Pahuaypite 1 is planned up to elevation 2,190 m for a total height of approximately 180 m (before the 10% capacity expansion). This deposit has a relatively small upstream catchment area and therefore does not have diversion channels. Surface runoff from the facility is graded to one side of the facility where it can flow down to the water management pond via a pair of pipes 4” and 6” in diameter.

 

Pahuaypite 2 is planned up to elevation 2,130 m for a total height of approximately 130 m (before the 10% capacity expansion). This deposit has two upstream diversion channels and an upstream check dam that is intended to help separate non-contact water from tailings. The upstream check dam is a water retaining dam with an upstream concrete face connected to a concrete plinth with curtain grouting. Tailings dry stack Pahuaypite 2 and supporting infrastructure are illustrated in Figure 15-3.

 

Monthly and annual dam safety inspections are currently being conducted by Geoconsultoria Ltda, an external consultant, for the Pahuaypite 1 and 2 dry-stack deposits. SLR relies on the conclusions of Geoconsultoria [two reports titled Evaluación Annual de Seguridad – 2018 for Pahuaypite 1 and Pahuaypite 2, dated March 15, 2019] and provides no conclusions or opinions regarding the stability of the listed tailings storage facilities.

 

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Figure 15-3: Tailings Dry Stack Pahuaypite 2 and Supporting Infrastructure

 

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15.5.3 Waste Rock Dumps

 

Waste rock from the underground mining operations is either used as backfill underground or stockpiled on the surface. Waste rock is stockpiled in six locations on the mine site, illustrated in Figure 15-2:

 

Clearing Platform 1910-1940,

 

Waste dump No. 1,

 

Waste dump No. 2,

 

Waste dump No. 7,

 

Waste dump No. 100, and

 

Pahuaypite waste dump.

 

The capacity of the clearing platform 1910-1940 is unknown, however, waste rock dumps Nos. 1, 2, 7, and 100 have a cumulative capacity of approximately 2.3 Mm3, although waste dump No. 100 is by far the largest at 1.8 Mm3. Pahuaypite waste dump is the newest and only operating waste rock dump for the mine operation; it has a waste rock storage capacity of 4.4 Mm3 (less than 1.2 Mm3 remaining) and is located immediately downstream of the Pahuaypite 2 water management dam. This water management pond will not have an emergency spillway while the Pahuaypite waste dump is in operation. At the closure of the Pahuaypite dump, a new spillway will be established to convey water in the valley around the waste rock dump.

 

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16.0 Market Studies

 

16.1 Markets

 

The principal commodities that are produced at the Cerro Lindo Mine – zinc, copper, lead, and silver – are freely traded at prices and terms that are widely known so that prospects for sale of any production are virtually assured. All of Cerro Lindo’s zinc concentrate will be processed at Nexa’s Cajamarquilla zinc refinery in Peru (61%) and Três Marias (35%) and Juiz de Fora (4%) zinc refineries in Brazil. Lead and copper concentrates will also be sold on the open market. Cerro Lindo is an operating mine with concentrate sales contracts in place for copper and lead concentrates. SLR has reviewed the concentrate terms provided by Nexa and found them to be consistent with current industry norms.

 

Market information for this section comes from the industry scenario analysis prepared by Nexa’s Market Intelligence team in July 2020 based on information sourced from different banks and independent financial institutions, economy and politics research groups, and metals consultants.

 

Nexa’s Market Intelligence team notes that the industry has progressed from volatile markets in 2019 due to US/China trade wars, Brexit, and development economies slowing down, to more uncertainty in 2020 due to the COVID-19 pandemic, a plunging global economy, the oil crisis, and the US elections. All these factors have affected the market fundamentals.

 

The SLR QP has reviewed the market studies and analyses and the results support the assumptions in the Technical Report Summary.

 

16.1.1 Zinc

 

16.1.1.1 Demand

 

The major market drivers for zinc demand are construction and infrastructure, transportation and vehicles production, industrial machinery production, batteries, and renewable energy. All these industries have been affected by the COVID-19 pandemic which has caused the global economy to slow down. As a result, zinc metal demand has also decreased in 2020, by approximately 10% year over year.

 

Nexa’s Market Intelligence team examined several scenarios for demand recovery and future growth, and settled on a base case that forecasts pre-COVID-19 levels of demand in the second half of 2022, with a demand compound annual growth rate (CAGR) of approximately 1.3% from 2023 to 2025. In 2019, they had forecasted a CAGR of approximately 1.7% between 2019 and 2024.

 

16.1.1.2 Supply

 

Nexa’s Market Intelligence team’s supply forecast analysis was based on the following industry information: zinc mine start-up and closure, mine production guidance, disruption allowance evaluation, project pipeline, and cost evaluation for 2020 onwards. Nexa’s forecast analysis results are summarized as follows:

 

Mine disruption factor: Based on independent data, Nexa has forecast a mine disruption factor of 4% for China and 4% until 2023 and 2% to 3% for 2024 and 2025 for the rest of the world (ROW).

 

Project Pipeline: The analysis considered greenfield projects forecast to begin production between 2020 and 2025.

 

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Zinc concentrate production evolution - Global: Recent market conditions due to the COVID-19 pandemic have affected mines worldwide, reducing investments and causing mine closures. As a result, zinc supply might be limited in the long term.

 

China concentrate evolution: China concentrate supply is expected to increase by 3% through the 2020 to 2025 cycle, but significantly depends on the ability of China’s small mines to survive amid lower price levels and volatile market conditions.

 

Zinc Global Market Balance: Based on the above considerations, Nexa’s forecast is for a significant zinc supply surplus in 2020 and 2021, with an increase in demand starting in the second half of 2022. From 2024 onwards, the global demand will exceed zinc supply.

 

16.1.1.3 Zinc Price Outlook

 

Zinc prices depend on variations in supply, demand, and the perceived supply/demand balance. The most commonly referenced currency for zinc transactions is US dollars. Nexa’s Market Intelligence team based on its analysis of zinc supply, demand, global balance, and zinc prices, forecasts stressed zinc prices in 2021 and 2022 (between $2,000/t and $2,300/t), with a potential price increase to greater than $2,700/t starting in 2024-2025, and a long term price of $2,449/t. Figure 16-1 shows the results of Nexa’s analysis.

 

 

Source: Nexa, 2020e

 

Figure 16-1:         Zinc Price Outlook (2020-2025)

 

16.1.2 Copper

 

16.1.2.1 Demand

 

The major market drivers for copper demand are power generation and transmission, construction, factory equipment, and the electronics industry. The COVID-19 pandemic affected copper demand in 2020 and, in the opinion of Nexa’s Market Intelligence team, will also impact it in the years ahead (2021 and 2022). In the long term, the team predicts a lower demand growth, mainly reflecting China’s economic transition, despite the positive contribution of global trends such as electric vehicles, renewable energy, and urbanization.

 

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Nexa analyzed multiple demand scenarios, with a Base Case forecasting a reduction in copper demand by 9.0% between 2019 and 2020, and starting in the second half of 2020, a slower-paced recovery with a demand CAGR of 3.2% between 2020 and 2025. Copper demand is predicted to grow from 26.9 Mt in 2020 to 31.5 Mt by 2025.

 

16.1.2.2 Supply

 

Nexa’s Market Intelligence team’s supply forecast analysis was based on the following industry information: copper mine start-up and closure, mine production guidance, project pipeline, and cost evaluation for 2020 onwards. Nexa’s forecast analysis results are summarized as follows:

 

Project Pipeline: The pipeline is short, mainly because there are fewer opportunities in mining-friendly jurisdictions.

 

Copper concentrate (sulphide) production evolution: Nexa considers that the majority of the production will come from sulphide mines. Nexa forecasts a concentrate production CAGR increase of 4.2% between 2020 and 2025. The increase in supply results from the ramp-up of brownfield projects.

 

Copper SXEW (oxide) production evolution: Nexa forecasts a downward trend for SXEW production. Based on Nexa’s analysis, a concentrate production CAGR will decrease by 2.7% between 2020 and 2025, as a result of by mine closures and reductions in production.

 

Refined Copper Market Balance: the copper market has been in deficit for the last three years, leading to lower stocks, despite lower prices since mid-2018 mainly due to the trade war between the USA and China, and the COVID-19 pandemic outbreak in 2020. Based on the above production assumptions, Nexa provided a forecast for Copper Market Balance between 2020 and 2025, showing a significant copper supply surplus in year 2020 and a slightly positive surplus in 2021 and 2022. From 2023 onwards, the global copper demand will create a deficit in copper supply (Figure 16-2).

 

 

Source: Nexa, 2020e

 

Figure 16-2:          Refined Copper Market Balance (2020-2025)

 

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16.1.2.3 Copper Price Outlook

 

Copper prices depend on variations in supply, demand, and the perceived supply/demand balance. Based on Nexa’s Market Intelligence team’s analysis of copper supply, demand, global balance, and copper prices, Nexa forecasts stressed copper prices between 2021 and 2024 (between $6,040/t and $6,351/t), with a potential price increase to higher than $6,500/t after 2024, and a long term price of $6,627/t. Figure 16-3 show the results of Nexa’s analysis.

 

 

Source: Nexa, 2020e

 

Figure 16-3:          Copper Price Outlook (2020-2025)

 

16.2 Contracts

 

16.2.1 Silver Streaming Agreement

 

Nexa has a silver streaming agreement with Triple Flag Mining Finance Bermuda Ltd. (Triple Flag) on silver production from the Mine. In exchange for an initial payment of US$250 million, Triple Flag has the rights to 65% of all payable silver, at a cost of 10% of the spot silver price (up to a total of 19.5 Moz Ag). After the total has been reached, currently anticipated to be 2027, Triple Flag is entitled to 25% of payable silver. The SLR QP has reviewed the silver streaming contract terms and is of the opinion that they are within industry norms.

 

16.2.2 Concentrate Sales Contracts

 

Cerro Lindo is an operating mine with concentrate sales contracts in place for copper and lead concentrates, with the main players in the world, between global traders and refineries. Zinc concentrate is consumed by Nexa’s Cajamarquilla zinc refinery in Peru (61%) and Três Marias (35%) and Juiz de For a (4%) zinc refineries in Brazil, according to their internal planning. Additional concentrate sales can be made at Nexa’s discretion. SLR has reviewed the concentrate terms provided by Nexa and found them to be consistent with current industry norms.

 

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Currently, the lead concentrate produced at Cerro Lindo averages 63.8% Pb including 75 oz/t Ag, while the copper concentrate averages 25.9% Cu including 14 oz/t Ag. In addition, there are no penalty contaminant elements in the zinc or lead concentrate. A small penalty of approximately $2/dmt applies to the copper concentrate due to the lead and zinc levels. The penalties could vary every year and according to each private negotiation.

 

16.2.3 Service Contracts

 

Various operational support services are provided by contractors, including underground mining, surface tailings haulage and placement, concentrate haulage, catering, security, and the mine site laboratory.

 

There are current 39 contractors providing the services as listed in Table 19-1.

 

Table 16-1:          Third Party Contractors 

Nexa Resources S.A. – Cerro Lindo Mine

 

Description   Number
Mine   7
Plant   1
Logistics   1
Security   1
Admin & Community Relations   1
Exploration   1
Maintenance   10
 Environment/ Infrastructure   4
Geology   2
Human Resources   1
Infrastructure   3
Total   32

 

SLR has not reviewed the different support service contract details and terms, however, Nexa has used these contractors in the past and continue to do so.

 

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17.0 Environmental Studies, Permitting, and Plans, Negotiations, or Agreements with Local Individuals or Groups

 

The information presented in this section is based on documentation provided by Nexa and meetings with mine site personnel. A site visit was conducted in support of the preparation of Section 17 of this Technical Report Summary from June 17 to June 20, 2019.

 

17.1 Environmental Studies

 

17.1.1 Mine Operation Overview

 

The Cerro Lindo Mine facilities and infrastructure are located in the districts of Chavín, Pueblo Nuevo, and Grocio Prado, in the province of Chincha (department of Ica), Perú. The Mine facilities and camps are located along the left bank of the Topará Creek in the occidental Andes Mountains, approximately 40 km northeast of the town of Chincha at elevations ranging from 1,820 MASL to 2,200 MASL. The desalination plant is located at sea level approximately 15 km northwest of the town of Chincha.

 

The mine operation started in July 2007. The community relations team was created in 2003, in parallel with the preparation and approval of the Environmental Impact Assessment (EIA), although it started to work actively in the mine area in 2005, one year before construction start-up. The mine life declared in 2011 was 12 years (up to year 2022). The current mine life is approximately nine years (until 2029) based on the most recent estimate of Mineral Reserves. The mining operation is comprised of the following main facilities:

 

Underground zinc-lead-copper-silver mine

 

Active waste rock dump (Pahuaypite) and inactive waste rock dumps (No. 1, No. 2, No. 7, and No. 100)

 

TSF Pahuaypite 1 and Pahuaypite 2

 

Tailings filter plant

 

Paste backfill plant

 

Water management ponds (contingency ponds downstream of the TSFs)

 

Temporary ore stockpile

 

Process plant

 

Landfill

 

Ancillary buildings (administration, storage, vehicle maintenance, medical center, solid residue disposal facilities, laboratories, gas station, magazine, etc.)

 

Permanent camps (five)

 

Transmission lines and electrical substations

 

Desalination plant

 

The Cerro Lindo process plant is a polymetallic flotation-based concentrator with a production rate of 20,600 tpd according to the current mine plan. The approved EIA grants authorization for a maximum production rate of 22,500 tpd. Processing is based on conventional crushing, grinding, sequential lead and copper bulk flotation followed by zinc rougher flotation, subsequent copper and lead separation and cleaner flotation, zinc cleaner flotation, and concentrate thickening and filtration to produce separate concentrates of zinc, lead, and copper with silver content.

 

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Tailings from the process plant are thickened and then further dewatered in either the paste plant to be deposited underground, or to the filter plant to the south of the process plant to be filtered and subsequently placed in two dry-stack storage facilities, Pahuaypite 1 and Pahuaypite 2. As much as 90% of the process water from dewatered tailings is recycled with industrial fresh water being supplied from a desalination plant at the coast to meet site and process water make-up requirements. At the Mine site, there is no fresh water withdrawal from natural water bodies and there is no discharge of industrial or treated sewage water to the environment.

 

17.1.2 Environmental Baseline

 

The summary of the baseline characterization presented below is based on the baseline analyses included in the 2018 EIA for the mine site and the desalination plant area near Chincha.

 

Climate. The Cerro Lindo Mine is located at the Topará valley, which has an arid, mesothermal climate with absent or very low excess water according to the Thornthwaite climate classification. Average annual temperatures at the mine site fluctuate from approximately 12.5ºC to 18.3ºC based on data from four meteorological stations. The average annual precipitation is 69.1 mm and the average annual potential evaporation is 1,500 mm. Relative humidity varies from 37% in July to 92% in March. The predominant wind direction is from the southwest.

 

Higher rainfall occurs between December and March and lower rainfall is typically from May to September. April, October, and November are transition months. The seasonality of precipitation is less pronounced in the area where the desalination plant is located relative to the mine site.

 

Air Quality. Concentrations of the air quality parameters (particulate matter, gases, and metals [As, Pb]) that were evaluated through 2010 to 2016 were found to be below the Peruvian environmental quality standards (ECA for its acronym in Spanish). The same conclusion applies to non-ionizing radiation for the monitoring period 2010 to 2016.

 

Ambient Noise. Noise levels evaluated through 2009 to 2016 were found to be below the Peruvian environmental quality standards for industrial areas in both day and night monitoring periods.

 

Surface Water Quality. The mining operation is located at the upper Topará Creek basin. The Topará Creek flows seasonally, with higher flow during the period from January to March. Since there is not much flow available, farming activities in the valley typically rely on groundwater. Flow monitoring is conducted in six stations located along the creek bed, upstream and downstream of the mine facilities.

 

Concentrations of the water quality parameters (pH, dissolved oxygen, conductivity, Weak Acid Dissociable [WAD] cyanide, and metals [As, Cd, Cu, Fe, Mn, Pb, Zn]) that were evaluated through 2010 to 2016 were found for the most part to be below the values stated in the Peruvian environmental quality standards (ECA Category 3 according to water use). The water quality analysis included in the 2018 EIA presented an individual discussion for each parameter explaining how the isolated exceedances in the data record are associated with transport of materials of the natural bed, and geological and mineralogical conditions inherent to the mine location. Parameter concentrations that exceeded the standards were also detected at monitoring stations outside the area of influence of the mine.

 

Sediment loads monitored at the same water quality stations were compared against the Canadian Interim Sediment Quality Guidelines (ISQG) and Probable Effect Level (PEL) standards in absence of Peruvian standards. Data show that arsenic, cadmium, mercury, lead, and zinc were consistently above the ISQG limits. The concentrations of these parameters in the sediments are associated with two factors: i) mineralization and hydrothermal alteration, and ii) external geodynamic processes mainly related to sediment transport (e.g., natural slides). A study by Amphos 21 Consulting Peru S.A.C. (Amphos 21, 2016) confirmed that the elements noted were the result of natural erosive and weathering processes from the surrounding lithologies and were not sourced from the mine.

 

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Surface water quality is also monitored at 15 stations in Jahuay beach where the desalination plant is located. Concentrations of the water quality parameters (pH, dissolved oxygen, biochemical oxygen demand, conductivity, salinity, total suspended solids (TSS), total dissolved solids (TDS), chlorides, oil and grease, nitrites, nitrates, and phosphates) that were evaluated through 2013 to 2016 were found for the most part to be below the values stated in the Peruvian environmental quality standards (ECA Categories 1 and 2 according to water use). The water quality analysis included in the 2018 EIA presented an individual discussion for each parameter explaining how the isolated exceedances in the data record are associated with factors not related to the operation of the desalination plant.

 

Groundwater Quality. Monitoring of groundwater quality was conducted by Vector in 2011 at five locations, and by Nexa Peru (formerly Milpo) from 2013 through 2015 at four locations. Results were referentially compared against the Peruvian environmental quality standards (ECA Category 3 according to water use) given that Peru does not currently have standards for groundwater quality. Registered exceedances are the result of the mineralogic characteristics of the deposit.

 

Flora and Fauna. The results of the biological monitoring campaigns include the identification of endemic, migratory, native, naturalized, exotic and/or threatened (according to national and international criteria), economic, ecological and/or socio-culturally important species, as well as the respective characterization indices. Periodic monitoring of terrestrial fauna and flora has been carried out since 2010. Monitoring of aquatic fauna and flora has been carried out since 2013. There are no natural protected areas within the mine’s area of influence.

 

A total of 20 species of terrestrial flora were identified in the mine area as having conservation status: 10 are endemic, nine species are included in Appendix II of CITES (2017), nine species are included in the 2017 International Union for Conservation of Nature (IUCN) annual report (IUCN, 2017), and thirteen species are registered in the Peruvian Ministry of Environment’s Supreme Decree (D.S.) No. 043-2006-AG.

 

A total of 20 species of terrestrial flora were identified in the desalination plant area as having conservation status: eleven are endemic, eight species are included in Appendix II of CITES (2017), seven species are included in IUCN (2017), and 10 species are registered in D.S. No. 043-2006-AG.

 

A total of 10 species of fauna were identified in the mine area as having conservation status: two are mammals, four belong to birdlife, and four belong to herpetofauna. A total of 17 species of fauna were identified in the desalination plant area as having conservation status: five are mammals, six belong to birdlife, and six belong to herpetofauna.

 

Social and Heritage Considerations. As reported in Amec Foster Wheeler plc’s NI 43-101 report (Amec, 2017), approximately 1,096 people, based on 2007 census figures, live in the Chavín district, and 98% of the population is classified as rural. Due to the elevation and rugged topography, much of the land is classified as unsuitable for agriculture. The primary land use is nomadic cattle grazing, with herds being constantly moved to locations where there is sufficient grass for food.

 

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Chavín village is not regularly used, with most villagers residing in Chincha. The indirect mine influence area is considered to be the entire province of Chincha and the general Ica region, as these areas benefit from mine royalty and taxation payments.

 

Archaeological surveys were conducted as part of the EIA process, and Nexa Peru holds the following Non-existence of Archaeological Remains certificates (CIRA):

 

CIRA No. 2006-0110, for the Jahuay–Cerro Lindo road, which confirms that there are no archaeological remains in the 60 km long road easement.

 

CIRA No. 2007-253 (July 2007), for the mining operations, desalination plant area, and the powerline, which confirms that there are no archaeological remains in the 443.92 ha mine direct influence area (area also includes a buffer zone around the operations). One small (2.16 ha) archaeological site, Patahuasi, was identified within the area reviewed for the CIRA permit.

 

CIRA No. 2010-381 (September 2010), for the power transmission line easement.

 

17.1.3 Environmental Studies and Key Environmental Issues

 

SLR has been provided with and reviewed the following documents and reports:

 

Modification of the Cerro Lindo Environmental Impact Assessment for Expansion of the Process Plant to 22,500 Metric Tonnes per Day prepared by SRK Consulting dated January/February 2018

 

o Physical Baseline

 

o Biological Baseline

 

o Social Baseline

 

o Characterization of Environmental Impacts

 

o Environmental Management Plan

 

Study of Contaminated Areas – Geochemical Characterization in Support of the Confirmatory Environmental Investigation. Technical memorandum prepared by Golder Associates dated May 17, 2019

 

Description of the Recirculation System of Domestic and Industrial Water – Zero-Discharge. Memorandum prepared by Nexa dated March 26, 2019

 

Quarterly reports for monitoring of surface water and groundwater quality in 2018 and 2019 prepared by SGS del Perú

 

Quarterly reports for monitoring of sediments in 2019 prepared by SGS del Perú

 

Quarterly reports for participatory monitoring of air quality in 2018 and 2019 prepared by SGS del Perú

 

Quarterly reports for monitoring of ambient noise in 2018 and 2019 prepared by SGS del Perú

 

Bi-annual reports for monitoring of air quality, ambient noise and electromagnetic fields for the power transmission line and sub-stations in 2019 prepared by SGS del Perú

 

Diagnostic of Compliance with ECAs in the Topará Creek – Study of Hydrogeochemistry and Water Quality prepared by Amphos 21 dated June 2016

 

Cerro Lindo Management Plan for Water and Liquid Effluents developed by Nexa (PGU-CL-SSMA-MA-E)

 

Cerro Lindo Preparedness and Emergency Response Plan developed by Nexa (CL-SSO-PL-01)

 

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Second amendment to the Cerro Lindo Mine Closure Plan prepared by Geoservice Ingeniería dated March 2016

 

Independent Technical Report pursuant to National Instrument 43-101 of the Canadian Securities Administrators for Cerro Lindo Mine, Perú. Report prepared by AMEC Foster Wheeler dated September 2017

 

Various EIA, modifications and Supporting Technical Reports (ITS for its acronym in Spanish) have been submitted and approved between 2004 and 2019. The most recent modification of the EIA approved in 2018 corresponds to the expansion of the process plant production rate to 22,500 tpd.

 

The key project effects and associated management strategies, as described in the 2018 EIA, are shown in Table 17-1. The Environmental Management Plan, which addresses mitigation measures and monitoring programs, was prepared as part of EIA development with the most recent update presented in the 2018 EIA. The Environmental Management Plan includes industrial and domestic effluent discharges, surface water quality and sediment, groundwater quality, surface flow, air quality (particulate matter and gas emissions), non-ionizing radiation, noise, vibrations, soil quality, terrestrial and aquatic flora, terrestrial and aquatic fauna. In the SLR QP’s opinion, the Environmental Management Plan is adequate to address potential issues related to environmental compliance.

 

The Environmental Management Plan states that no environmental compensation plan is required because the proposed mitigation measures ensure the preservation of the ecosystem and biodiversity of the mine site area, and all the potential environmental effects were characterized as no significant in the EIA (SRK, 2018).

 

No environmental issues were identified by SLR from the documentation available for review that could materially impact the ability to extract the mineral resources and mineral reserves.

 

Table 17-1:          Summary of Key Environmental Effects and Management Strategies 

Nexa Resources S.A. – Cerro Lindo Mine

 

Environmental Component   Potential Impact   Management Strategies
Soils  

Changes to soil uses

 

Changes to soil quality

 

 

Implementation of spills management plan for hazardous materials.

 

Implementation of spill containment at potential accidental spill sources, as applicable.

 

Relocation of soils contaminated as a result of hazardous materials spills in appropriate facilities.

 

Provision of oil and grease traps at vehicle maintenance facilities.

 

Tire washing of hauling trucks following concentrate loading.

 

Adequate management of industrial and domestic waste.

 

Development of appropriate topsoil deposits equipped with erosion controls.

 

Timely rehabilitation of disturbed areas.

 

Annual monitoring at five locations following R.M. No. 085-2014-MINAM (national guideline for soils monitoring) and the national environmental quality standards applicable to soils (D.S. No. 002-2013-MINAM and D.S. No. 002-2014-MINAM) for industrial zones. 

 

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Environmental Component   Potential Impact   Management Strategies
Geochemistry   Changes to surface water quality and/or groundwater quality   Geochemistry sampling evaluation program for tailings and waste rock.
         
Surface water  

Changes to surface water flows

 

Changes to surface water quality

 

 

Maximize water recirculation and re-use at the mine.

 

Zero water discharge to the environment at the mine site.

 

No fresh water withdrawal from natural water bodies at the mine site.

 

Treatment of domestic sewage water prior to reusing it in the process plant.

 

Desalination plant equipped with reverse osmosis water treatment plant.

 

Regular inspections and maintenance program for water management infrastructure.

 

Implementation of oil and grease traps.

 

Inherent design measures such as design of discharge pipes from the desalination plant to promote brine dilution in a short distance.

 

Protection of river and creek beds (e.g. controlled traffic of vehicles, no earth movements near stream beds, no washing of vehicles or machinery in stream beads, etc.).

 

Quarterly water quality monitoring at one effluent discharge location at Jahuay beach for parameters listed in D.S. No. 010-2010-MINAM (national maximum permissible limits for liquid effluents from mining and metallurgic activities).

 

Monthly water quality monitoring of natural streams at six stations located at the mine site area following the national protocol for surface water quality monitoring (R.J. No. 010--2016-ANA) for water bodies classified as Category 3.

 

Monthly monitoring of maritime surface water quality at nine stations located in Jahuay beach following the national protocol for surface water quality monitoring (R.J. No. 010-2016-ANA), and using D.S. No. 004-2017-MINAM (national environmental water quality standards) for categories 1 and 2 as the reference to determine compliance.

 

In absence of national sediment quality standards, the Canadian Environmental Quality Guidelines (2003) are used as the reference to evaluate the environmental performance for both continental and maritime surface water.

 

Groundwater  

Changes to phreatic level

 

 

Changes to groundwater quality

 

 

Implementation of seepage collection systems for waste management facilities for water re-use (and treatment if necessary).

 

Identification of natural recharge zones due to fractures or faults.

 

Monthly groundwater quality monitoring in eight piezometers located upstream of the mine site and downstream of waste rock dumps, TSFs and landfill. In the absence of national groundwater quality standards, the Canadian Water Quality Guidelines for the Protection of Aquatic Life issued by the Canadian Council of Ministers of the Environment (2003) are used as the reference to evaluate the environmental performance. 

 

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Environmental Component   Potential Impact   Management Strategies
Air quality   Changes from particulate and gas emissions  

Regular preventive maintenance of vehicles and motorized equipment.

 

Regular irrigation of access roads with tanker trucks and sprinkler systems.

 

Irrigation of areas where mobile grinders are operated.

 

Speed limit of 30 km/hr for vehicles circulating within the mine site according to the internal traffic regulations of Cerro Lindo.

 

Transportation of materials in covered hoppers.

 

Monitoring of particulate matter (PM10 and PM2.5), metals (arsenic and lead), and gases (SO2, NO2, CO). Quarterly monitoring at nine stations at the mine site, and biannual monitoring at five stations at the desalination plant area. Compliance is determined according to applicable national air quality standards from D.S. No. 003-2017-MINAM. The selected parameters are consistent with R.D. No. 239-2011-MEM/AAM (08/08/11).

 

Biannual monitoring of non-ionizing radiation at three stations located at the mine site and 13 stations located along the service corridors following the national environmental quality standards for non-ionizing radiation (D.S. No. 010-2005-PCM).

 

Noise and vibration   Disturbances resulting from changes to ambient noise levels and generation of vibrations  

Use of hearing protection devices.

 

Appropriate planning and optimization of machinery and equipment usage.

 

Avoid simultaneous usage of transportation, demolition, and excavation vehicles.

 

Avoid honking vehicle horns except for safety practices to prevent accidents.

 

Regular vehicle maintenance.

 

Implementation of blasting controls.

 

Quaternary noise monitoring at three stations located at the mine site and biannual noise monitoring at 17 stations located along the service corridors (seven along the transmission line, nine along the water supply pipeline, and one at the road near Jahuay beach). Compliance is determined according to the maximum permissible limits from the national environmental quality standards for noise (D.S. No. 085-2003-PCM) for industrial zones.

 

There are no inhabitants living close enough to the mine site to be potentially affected by vibrations. Hence, vibrations monitoring was not included in the monitoring program. 

 

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Environmental Component   Potential Impact   Management Strategies
Aquatic flora and fauna   Changes in abundance and diversity of aquatic species  

Environmental controls for protection of local flora and fauna (several measures are outlined in the 2018 EIA).

 

Respecting the ecosystem when carrying out any activities associated with the mine operation and closure.

 

Zero discharge of industrial or sewage water to the environment at the mine site.

 

Meeting water quality standards at points of effluent discharge to the environment (i.e., brine concentration from desalination plant discharge in Jahuay beach).

 

Prohibition to dispose of solid or liquid waste in natural water bodies.

 

Prohibition to capture fish in the mine concession areas and surroundings.

 

Prohibition to introduce non-native species.

 

Personnel training.

 

Biannual monitoring (dry and wet seasons).

 

Terrestrial flora and fauna  

Changes to vegetation cover and diversity of terrestrial flora

 

Changes to sensitive species of wild flora

 

 

Environmental controls for protection of local flora and fauna (several measures are outlined in the 2018 EIA).

 

Respecting the ecosystem when carrying out any activities associated with the mine operation and closure.

 

Prohibition to collect flora.

 

Prohibition to introduce non-native species.

 

Prohibition of hunting, fishing, and capture of fauna within the mine concession areas and surroundings.

 

Personnel training.

 

Rescue or relocation of species, if required, in agreement with methods outlined in the 2018 EIA.

 

Consideration of location of endemic species tagged for conservation when deciding on location of mine facilities.

 

Prohibition to dispose of solid or liquid waste in the mine site area outside of the spots designated for this purpose.

 

Biannual monitoring (dry and wet seasons).

 

Landscape   Changes in landscape’s visual quality  

Mine planning to minimize and control relief alterations.

 

Slope physical stability.

 

Smoothing of ground surface where applicable with implementation of banks to facilitate re-vegetation and prevent erosion.

 

Re-vegetation. 

 

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17.1.4 Environmental Management System

 

Nexa uses an ISO 14001 compliant environmental management system at Cerro Lindo to support environmental management, monitoring and compliance with applicable regulatory requirements during operation.

 

Nexa does not have an Environmental Policy for Cerro Lindo. According to Nexa’s website and the 2019 Nexa annual report, the company identifies and manages the main risks from both an operational and a strategic point of view, reducing and mitigating impacts to maintain business sustainability. The company has an integrated management system that establishes the guidelines that govern the conduct of the businesses, with a focus on quality management of environmental, health, and workplace safety and social responsibility issues. In addition, the company follows applicable environmental laws and regulations pertaining to its business in each country where it operates (Nexa, 2019).

 

Nexa has stated the following environmental goals in its 2020 annual report:

 

75% of recirculation and lower specific use of water.

 

Reduce the specific emission of greenhouse gases by 5%.

 

Decrease the disposal of tailings in dams and reduction by 50% in the specific generation of mining and smelting waste.

 

Ensure that 100% of the units have a pre-prepared future-use alternative study and an updated decommissioning plan, in line with the sector’s benchmark standards.

 

17.2 Mine Waste and Water Management

 

17.2.1 Environmental Geochemistry

 

The tailings have been identified as having a high acid generating potential, and metal leaching is anticipated. Acid generation in the tailings is a result of the presence of sulphides in the tailings, mainly in the form of pyrite. Laboratory testing identified high concentrations of the following metals from leach tests: aluminum, arsenic, cadmium, cobalt, copper, iron, manganese, and zinc (Golder, 2019). Water quality concerns are mitigated by the relative lack of precipitation at the mine site, and managed by the infrastructure in place for seepage collection.

 

Geochemical testing completed by Golder (2019) identified most of the waste rock to be potentially acid generating (PAG) with exception of some neutral to uncertain results from waste dump No. 2. Acid generation in the waste rock is a result of the presence of sulphides in the rock, mainly in the form of pyrite. Metal leaching laboratory testing identified high concentrations of cadmium, copper, and zinc. Water quality concerns are mitigated by the relative lack of precipitation at the mine site and managed by the seepage collection infrastructure in place for the larger waste rock dumps.

 

17.2.2 Mine Waste Management

 

The tailings dry stacks were designed for a 1:500-year return period earthquake, however, Ausenco (2017) identified a need to evaluate the facility design for the maximum credible earthquake. Given the relatively high seismic activity of the region, and the presence of these structures for perpetuity, Ausenco’s recommendation appears to be warranted.

 

Pahuaypite 1 and 2 are monitored using Casagrande type piezometers, inclinometers, and survey monuments. Inclinometers in Pahuaypite 1 have indicated a deformation between the natural ground and the dry stack of approximately 35 mm, or 10 mm per year. This deformation should continue to be monitored. Piezometers indicate that the stack is unsaturated. A cross-check of the tailings deposits conducted by Ausenco in 2017, and more recent annual inspection reports by Geoconsultoria (2018), indicate that there are no unusual trends in the tailings movement and that the phreatic surface of the dry stacks is near or below the interface between natural ground and tailings. No significant issues noted in monthly inspections up to April 2020.

 

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17.2.3 Tailings Storage Facilities and Waste Rock Dumps Closure

 

At closure the geometry of the tailings dry stacks will be checked to conform with the design of 2H:1V bench slopes with 20 m tall benches. The dry stacks will be covered with geomembrane placed between resistant non-woven geotextile to promote geochemical stability of the acid generating tailings. The geosynthetics will be covered by 0.3 m of sand and gravel to protect the geomembrane and promote drainage. Upstream hydraulic structures such as the diversion channels and check dam will be maintained. The water management (contingency) pond will be partially backfilled with inert materials to achieve a surface with stable slopes.

 

The closure concept for the Pahuaypite waste rock dump and waste dump No. 100 is similar to the tailings dry stacks. The dumps will be covered with a geosynthetic clay liner protected on both sides by a layer of geotextile. The geosynthetic materials will be covered with sand and gravel 0.35 m thick on the slopes and 0.55 m thick on the dump crest. Closure concept details for the other waste rock dumps were not available for review.

 

Post-closure monitoring of the rehabilitated areas will continue for at least five years to confirm physical and geochemical stability. Seepage collection and treatment at the waste rock dumps might need to continue post-closure depending on water quality conditions (geochemistry analysis of waste rock samples showed high acidity generation potential).

 

17.2.4 Water Management

 

The primary objective for water management is to provide enough availability of water to meet the mine operation water demands, and to ensure that the water quality and quantity of water bodies on the environmental influence area of the Cerro Lindo Mine site are not impacted by the operation.

 

Water conservation is a primary objective in Cerro Lindo due to the limited water availability in the area. Water is recycled and re-used as much as possible. Recycled water is obtained from the thickening process, tailings thickening process, and the filtration process. A permit to recycle a total annual volume of 3,689,712 m3 of industrial wastewater has been granted (Directorate Resolution (D.R.) No. 1382/2007/DIGESA/SA dated May 2007). This permit remains in effect as long as Nexa does not amend or change any of the activities that were allowed under the permit, which also makes reference to the zero-discharge commitment. If an unscheduled discharge was required, Cerro Lindo must obtain authorization from Dirección General de Salud Ambiental (DIGESA) for such discharge. Quarterly monitoring reports to the national authorities in compliance with Article 9 of R.M. No. 011-96-EM/VMM are not applicable to the Cerro Lindo operations due to the zero-discharge commitment for industrial and domestic water.

 

Service water is primarily used underground for drilling water, cooling, dust control, and concrete/shotcrete service. Service water is provided from a central plant-wide source and distributed underground via a system of pipelines to all working areas. The mine makes very little water from geological sources. Service water is collected and pumped to the surface where it is treated for re-use.

 

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Industrial fresh water is supplied from a desalination plant located at the coast to meet site (e.g., dust suppression) and process water make-up requirements (Figure 17-1). In addition, groundwater extraction from five groundwater wells/boreholes for a combined maximum annual flow of 48 L/s is authorized by various permits. There is no fresh water withdrawal from natural water bodies at the mine site. Approximately 60% of the total fresh water supply to the mine site is taken from the ocean with approximately 40% taken from groundwater wells.

 

 

(Source: Nexa Resources S.A.)

 

Figure 17-1:          Water Supply System for Cerro Lindo Mine

 

The pumping system from the desalination plant is divided into three stages to transport the water approximately 45 km to an elevation of 2,200 m. Three pump stations are located along the six-inch pipeline route from the desalination plant to the mine site. The desalination plant takes water from the ocean with an approved maximum rate of 100 L/s (3,153,600 m3/yr) according to D.R. No. 033-2012-ANA-ALA/MOC (SRK, 2018). The desalination plant discharges residual water from the treatment process to Jahuay Beach, which was approved by D.R. No. 002-2015-ANA-DGCRH for an annual flow of 72 L/s (SRK 2018). D.R. No. 008-2019-ANA-DCERH grants renewed authorization for effluent discharge from the desalination process. D.R. No. 0706-2012-MGP/DCG grants authorization of aquatic area usage for the submarine pipelines required for water intake and effluent discharge from the desalination process.

 

The mine has implemented three water treatment plants for industrial water, potable water, and domestic water (sewage). The industrial effluent treatment plant consists of a basic system of mine water clarification using three ponds. The first pond promotes settling sediments by their own weight; the second pond is used to control pH (target between 7 and 8) through lime addition and control conductivity to regulate initial metal elements present in the water; the third pond assists with precipitation of fines and water clarification prior to the water being recirculated to the process plant. There is no discharge of industrial or treated sewage water to the environment (zero-discharge commitment).

 

Clean water is diverted around the mine infrastructure, TSFs, and waste rock dumps where possible. Contact water resulting from surface runoff within the mine complex footprint is managed through channels and a check dam located at the head of the valley of the Pahuaypite 2 TSF. The flows are directed to lined contingency ponds at the base of the deposits. Water collected in the contingency ponds is pumped to the industrial treatment plant.

 

An underdrain system was constructed at the foundation/base of the TSFs (basal drainage) to conduct surface flows from the foundation toward the contingency ponds. The waste rock dumps are also equipped with an underdrain system to capture infiltration.

 

The most recent geochemical evaluation was conducted in 2019 on five tailings samples collected from the TSFs (Pahuaypite 1, Pahuaypite 2), and nine rock samples collected from waste rock dumps Nos. 1, 2, 7, and 100. Static geochemical testing included acid base accounting (ABA), elemental rock analysis, net acid generation (NAG) and metal leaching tests, and shake flask extraction (SFE) test. According to the results, in general, the tailings and waste rock samples showed high acidity generation potential. Tailings and waste rock at Cerro Lindo come from volcanic rocks, rich in massive sulphides mainly comprised of pyrite (50% to 95%). Pyrite oxidation generates acidity and could promote contact water with high concentrations of aluminum, arsenic, cadmium, cobalt, copper, iron, manganese, and zinc. Water quality concerns are mitigated by the relative lack of precipitation at the mine site and managed by the infrastructure in place for seepage collection.

 

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It is noted that a water management protocol developed by Nexa for the Cerro Lindo Mine documents a glossary of terms and definitions associated with water management, and outlines procedures and responsibilities addressing risk evaluation, legal commitments, objectives and target, operational controls, monitoring, and performance indicators.

 

17.3 Project Permitting

 

The Cerro Lindo mine operation is managed according to the environmental and closure considerations presented in three type of documents, which must be approved by directorial resolutions from the Peruvian government:

 

EIA and subsequent amendments and modifications

 

Supporting Technical Reports (ITS for its acronym in Spanish)

 

Mine Closure Plan

 

Cerro Lindo complies with applicable Peruvian permitting requirements. The permits are Directorial Resolutions (RD for its acronym in Spanish) issued by the Peruvian authorities upon approval of mining environmental management instruments filed by the mining companies such as EIAs, ITS and Mine Closure Plans. The approved permits for Cerro Lindo address the authority’s requirements for operation of the underground mine, TSFs, waste rock dumps, process plant, water usage and effluents discharge.

 

Nexa maintains and up to date record of the legal permits obtained to date, documenting the approving authority, validity period and expiry dates, status (current, canceled or superseded), and indicating if renewal is needed or not. The list of approved legal permits for Cerro Lindo provided by Nexa for review addresses the following aspects:

 

Environmental impact assessment

 

Domestic water treatment

 

Industrial water treatment (Process Plant)

 

Groundwater wells for exploration drilling

 

Use of aquatic area

 

Air and water quality monitoring locations

 

Mine closure planning

 

Beneficiation concessions

 

Mine operation certificates

 

Mine plans for mineral extraction

 

Infrastructure

 

Regulated chemical product supplies

 

Use of fuel

 

Licences for use of explosives

 

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Absence of archaeological remains

 

The Directorial Resolutions on environmental certifications, effluent discharge, water use, mine closure and tailings management are listed in Table 17-2. According to the record of the legal permits provided by Nexa in October 2020, the licences granted for use of water, the approved environmental certifications (i.e., EIAs and ITS), the approved mine closure plans and the licences granted for tailings disposal do not have lapsing dates and therefore renewal dates are not applicable. The Third Amendment to the Mine Closure Plan is under review and approval process by the Peruvian Authorities.

 

Table 17-2:           Environmental, Mine Closure and Tailings Disposal Licences 

Nexa Resources S.A. – Cerro Lindo Mine

 

Authority   Obligation/Licence   Date of Issue
Environmental Certifications
DGAAM   EIA Cerro Lindo Mine - RD N° 325-2004-MEM-AAM   2/7/2004
DGASA   Approval of EIA for the Jahuay Road Project, Cerro Lindo Mine - RD N° 037-2006-MTC-16   30/5/2006
DGAAM   EIA for Water Supply, Power, and Desalination Plant - RD N° 134-2007-MEM-AAM   2/4/2007
DGAAM   First Amendment to the EIA, Cerro Lindo Mine - RD N° 204-2007-MEM-AAM   8/6/2007
DGAAM   Second Amendment to the EIA, Cerro Lindo Mine – 10,000 MT/day - RD N° 168-2010-MEM-AAM   17/5/2010
DGAAM-MINEM   Amendment to the EIA for “Production Expansion to 10,000 MT/day and Water Supply, Power, and Desalination Plant” - RD N° 239-2011-MEM/AAM   8/8/2011
DGAAM   ITS for Installation of By-Pass and Third Mill, Cerro Lindo Mine - RD N° 069-2014-MEM-AAM   30/1/2014
DGAAM   ITS for Production Expansion to 17,988 MT/day, Cerro Lindo Mine - RD N° 391-2014-MEM-AAM   31/7/2014
SENACE   ITS for Pahuaypite 1 Raising and Expansion of the Contingency Pond - RD N° 048-2016-SENACE/DCA   14/7/2016
DGAAM   Approval of Detailed Technical Memorandum (MTD) - Cerro Lindo Mine - RD N° 258-2016-MEM-DGAAM   31/8/2016
SENACE   Modification of the EIA for the Cerro Lindo Mine - RD N° 39-2018-SENACE   13/3/2018
SENACE   ITS for Auxiliary Facilities - RD N° 001-2019-SENACE-PE/DEAR   3/1/2019
SENACE   ITS for Expansion of the Concentrator Plant to 22,500 MT/day and Additional Facilities - RD N° 134-2019-SENACE-PE/DEAR   22/8/2019
SENACE   ITS for Expansion of the Concentrator Plant to 22,500 MT/day and Additional Facilities - RD N° 00145-2020-SENACE-PE/DEAR   2/12/2020

 

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Authority   Obligation/Licence   Date of Issue
Effluent Discharge Authorization
ANA  

Effluent Discharge Authorization for Desalination Plant (Brine) - RD N° 008-2019-ANA-DGCRH 

Expires on February 16, 2023 

  16/2/2019
Water Use Licences
ALA Chincha - Pisco   Groundwater Use Licence (Well No. IRHS 182) - RA N° 057-2009-ANAALACH-P   8/4/2009
ALA Chincha - Pisco   Groundwater Use Licence (Well No. IRHS 183) - RA N° 058-2009-ANAALACH-P   8/4/2009
ALA San Juan   Groundwater Use Licence (Well No. IRHS 179) - RA N° 026/2011-ANA-ALA S.J   29/4/2011
ALA San Juan   Groundwater Use Licence (Well No. IRHS 180) - RA N° 027/2011-ANA-ALA S.J.   29/4/2011
ALA San Juan   Groundwater Use Licence (Well No. IRHS 181) - RA N° 028/2011-ANA-ALA S.J.   29/4/2011
ALA Mala - Omas - Cañete   Sea Water Use Licence, Cerro Lindo Mine - RA N° 033-2012-ANA-ALA-MOC   2/3/2012
Sanitary Wastewater Treatment Authorization
DIGESA   Sanitary Authorization for Water Treatment System for the Cerro Lindo Concentrator Plant (Zero Effluent Discharge) - RD Nº 1382/2007/DIGESA/SA   17/5/2007
DIGESA   Sanitary Authorization for Water Treatment System for Human Consumption at the Cerro Lindo Mine - RD Nº 0231/2021/DIGESA/SA
Expires on January 14, 2025
  14/1/2021
Mine Closure Plan
DGAAM   Mine Closure Plan, Cerro Lindo Mine - RD N° 326-2009-MEM.AAM   20/10/2009
DGAAM   First Amendment to the Mine Closure Plan, Cerro Lindo Mine - RD N° 432-2012-MEM-AAM   19/12/2012
DGAAM   First Update of the Mine Closure Plan, Cerro Lindo Mine - RD N° 084-2013-MEM-AAM   22/3/2013
DGAAM   Second Amendment to the Mine Closure Plan, Cerro Lindo Mine - RD N° 287-2016-MEM-DGAAM   29/9/2016
Tailings Disposal
DGM - MINEM   Construction Authorization for the Pahuaypite 2 Tailings Storage Facility and Contingency Facility - RD N° 284 - 2011 -MEM-DGM/V   10/8/2011
DGM - MINEM   Construction Authorization for Temporary Tailings Storage Facility - RD N° 032-2012-MEM-DGM/V   18/1/2012
DGM - MINEM   Authorization for Operation of the Temporary Tailings Storage Facility and Contingency Pond - RD N° 138-2012-MEM-DGM/V   3/5/2012
DGM - MINEM   Authorization for Operation of the Pahuaypite 2 Filtered Tailings Storage Facility - RD N° 323-2013-MEM-DGM/V   10/10/2012

 

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Authority   Obligation/Licence   Date of Issue
DGM - MINEM   Consent for the Pahuaypite 1 Tailings Storage Facility Raising and Authorization for Construction and Operation - RD N° 0543-2016-MEM-DGM/V   6/9/2016
DGM - MINEM   Modification of Construction Authorization for the Pahuaypite 1 Tailings Storage Facility - RD N° 0260-2018-MEM-DGM/V   21/3/2018
DGM - MINEM   Consent for the Pahuaypite 2 Tailings Storage Facility 10% Raising and Authorization for Construction and Operation - RD N° 0571-2019-MINEM-DGM/V   19/11/2019

 

17.4 Social or Community Requirements

 

17.4.1 General Context

 

The Cerro Lindo Mine is located in the District of Chincha in the Department of Ica, Peru. The underground mine is located approximately 240 km southeast of Lima, the capital city of Peru and 75 km northeast of Chincha, the closest major urban settlement area. The Cerro Lindo Mine is located inland and upland from both Lima and Chincha and is accessible by road.

 

This section presents the results of the social review based on a review of Nexa’s policies, programs, social risk management systems, and/or social performance against relevant International Finance Corporation (IFC) Performance Standards (PS). The IFC PSs have been used as a framework but this social review does not represent a detailed audit of Nexa’s compliance with IFC PSs or specific guidelines. Nexa’s social performance is benchmarked against the following IFC 2012 PSs:

 

PS1: Social and Environmental Assessment and Management Systems requires that companies identify, assess, and mitigate the social and environmental impacts and risks they generate throughout the lifecycle of their projects and operations. From a social perspective, the requirement includes: a comprehensive social assessment; identification of critical social impacts and risks; community consultation and engagement; information disclosure; mitigation plans to address impacts and risks; and development of an organizational structure with qualified staff and budgets to manage the overall social management system.

 

PS2: Labour and Working Conditions incorporates the International Labour Organization conventions that seek to protect basic worker rights and promote effective worker/management relations.

 

PS4: Community Health and Safety declares the project’s duty to avoid or minimize risks and impacts to community health and safety and addresses priorities and measures to avoid and mitigate project related impacts and risks that might generate community exposure to risks of accidents and diseases.

 

PS5: Land Acquisition and Involuntary Resettlement considers the need for land acquisition or involuntary resettlement of any individual, family or group; including the potential for economic displacement.

 

PS7: Indigenous Peoples considers the presence of Indigenous groups, communities, or lands in the area that may be directly or indirectly affected by projects or operations.

 

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PS8: Cultural Heritage. This standard is based on the Convention on the Protection of the World Cultural and Natural Heritage. The objectives are to preserve and protect irreplaceable cultural heritage during a project’s operations, whether or not it is legally protected or previously disturbed and promote the equitable sharing of benefits from the use of cultural heritage in business activities.

 

It is noted that PS3 Resource Efficiency and Pollution Prevention and PS6 Biodiversity Conservation correspond to environmental performance standards. Environmental management and performance are discussed at the beginning of Section 17.

 

17.4.2 Social and Environmental Assessment and Management Systems

 

At a corporate level, Nexa has adopted the guidelines of the International Integrated Reporting Council (IIRC) and the standards for the Global Reporting Index (GRI). The IIRC guidelines promote a cohesive and integrated approach to reporting on organizational activities. The GRI standards provide best practices for public reporting on economic, environmental, and social impacts in order to help Nexa and its shareholders and stakeholders understand their corporate contribution to sustainable development. These standards were reported on in the most recent Nexa Annual Performance Report for 2019 (Nexa, 2020f). With respect to social issues, the 2019 Annual Report provided details of corporate activities aligning with the following GRI Standards:

 

1. Employment

 

2. Occupational health and safety (OHS)

 

3. Non-discrimination

 

4. Training and education

 

5. Diversity and equal opportunities

 

6. Freedom of association and collective bargaining

 

7. Child labour

 

8. Forced or compulsory labour

 

9. Human rights assessment

 

10. Local communities

 

11. Social assessment of suppliers

 

12. Socio-economic compliance

 

Nexa’s 2019 Annual Report also includes reporting on corporate progress towards several sustainable development goals. With respect to social environment issues, these include:

 

1. Gender equality

 

2. Decent work and economic growth

 

3. Good health and well-being

 

4. Peace, justice, and strong institutions

 

5. Quality education

 

6. Reduced inequalities

 

7. Sustainable cities and communities

 

8. Responsible consumption and production

 

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9. Life below water

 

Nexa has a corporate compliance policy (PC-RCC-CCI-005-EN) meant to guide Nexa representatives and third parties. The compliance policy includes the following policies and procedures:

 

1. Code of Conduct

 

2. Anti-Corruption Policy

 

3. Money Laundering and Financing Terrorism Prevention Policy

 

4. Antitrust/Competition Policy

 

5. Insider Trading Policy

 

6. Disclosure Policy

 

7. Compliance Program Manual

 

8. Money Laundering and Financing Terrorism Prevention Manual

 

9. Gifts and Hospitality Procedure

 

10. Relationships with Government Representatives Procedure

 

11. Travel and Entertainment Procedure

 

12. Integrity Due Diligence Procedure

 

13. Conflict of Interests Procedure

 

With respect to Cerro Lindo operations, Nexa has developed and utilizes a number of social management programs and tools to help the company work with the nearby communities. These include:

 

1. Fulfilling Commitments and Obligations

 

o Compliance matrix of commitments and obligations

 

o Execution matrix

 

2. Impact and Expectation Matrix

 

o Local employability program

 

o Local supply program

 

o Local development program

 

o Volunteering program

 

3. Community Relationship and Social Responsibility

 

o Stakeholder matrix

 

o Interactions matrix

 

o Reporting tools

 

4. Social Conflict Management

 

o Social conflict management and reporting program

 

o Complaint resolution and care system

 

In order to better understand community-specific issues and address concerns that arise at Cerro Lindo, Nexa implements a complaint register guided by Nexa’s Order and Complaint Procedure, which details roles, responsibilities, and commitments to gather and respond to complaints from the public in a fair and equitable way. All communications and complaints are recorded, investigated, evaluated, and resolved according to the Order and Complaint Procedure. The process is meant to provide Nexa with a better understanding of the local population and related issues. Nexa also maintains a compliance matrix, which is a database of relevant stakeholders and a matrix/listing of interactions with each stakeholder.

 

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Nexa is currently seeking to extend and complete additional installations at Cerro Lindo. In order to understand the potential effects of the Cerro Lindo Mine, Nexa is relying on impact assessment studies completed in 2018 by a third-party consultant. This assessment includes a social environment impact assessment, comprised of a Social Baseline, an Environmental Impact Characterization, and an Environmental Management Strategy, which are all generally consistent with Social Impact Assessment Practices.

 

The Social Baseline includes a description of:

 

The social areas of influence;

 

The social, economic, and cultural characteristics of the population of the areas of influence of the project;

 

Social-economic variables that might be affected by the project;

 

Potential indicators to assess impacts of the project;

 

Identification of the main social and environmental issues of relevance to the population;

 

Perceptions and expectations of members of the public and other stakeholders regarding Cerro Lindo mining activities and socio-economic development; and

 

The foundation for a social impact management plan to mitigate potential negative impacts and maximize potential positive benefits.

 

The preceding was accomplished through a variety of methods including both primary and secondary data collection. Primary data collection included field investigations such as surveys and interviews. Secondary data collection included reviews of legal documentation, information related to the areas of influence and inhabited areas, and other permits and approved studies relevant to the Cerro Lindo Mine.

 

The Environmental Impact Characterization assesses the potential impacts of the Cerro Lindo Mine at the various stages and includes an assessment of potential negative and positive impacts of the Mine on the social environment. These variables include:

 

1. Health

 

2. Education

 

3. Local Economy and Trade

 

4. Demographics

 

5. Cultural

 

6. Quality of Life and Human Development

 

The Environmental Management Strategy includes an Environmental Management Plan and Social Management Plan to mitigate negative impacts and maximize positive benefits of the Cerro Lindo Mine. The Social Management Plan includes a description of community needs and expectations, social projects and community benefits, and recommendations to improve the social and economic environments in the areas of influence. The Social Management Plan includes the following sub-plans:

 

1. Communications Plan

 

2. Community Relations Plan

 

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3. Community Development Plan

 

Each plan is based on the empirical research and document review from the Social Baseline and Environmental Impact Characterization reports, and includes detailed descriptions of activities, budgets, timeframes, as well as measures and indicators. In the SLR QP’s opinion, the Social Management Plan is adequate to address potential issues related to local communities.

 

The studies employed targeted surveys, interviews, and outreach with members of the public, government officials, and other stakeholders to inform the social impact assessment. The information was reviewed to understand trends and commonalities in the main social and environmental issues perceived by the public and other stakeholders. The data and reports provide a thorough account of Nexa’s approach to identify, assess, and mitigate social risks related to the Cerro Lindo Mine.

 

17.4.3 Labour and Working Conditions

 

Corporately, Nexa reports that 100% of its workers in Brazil are covered by collective bargaining units but does not report on the status in Peru. Nexa also reports corporately on the freedom of association and collective bargaining. Some of the Sustainable Development Targets identified by Nexa include (but are not limited to):

 

By 2030 achieve full and productive employment and decent work for all women and men, including for young people and persons with disabilities, and equal pay for work of equal value; and

 

Protect labour rights and promote safe and secure working environments for all workers, including migrant workers, in particular migrant women, and persons in precarious employment.

 

As of August 2020, 358 of 595 workers at Cerro Lindo were unionized. At the time of this writing, two workers’ organizations were in place at Cerro Lindo.

 

Nexa has adopted OHS policies to ensure the protection and promotion of the safety, human health, and welfare of employees. Corporately, Nexa reports on its health and safety performance and highlights safety as its “greatest asset”. Several corporate initiatives are aimed at promoting safety, ensuring workers and contractors are trained, and that processes are in place to address any incidents that arise. In Peru, Nexa has advanced its Peru Safety Plan, which was reported to be 80% complete in the 2018. The Peru Safety Plan includes eight pillars:

 

1. Leadership training and awareness

 

2. Strengthening the OHS team

 

3. Implementation of the Outsourcing Management Program

 

4. Improvement of wellness and work regime conditions in the units

 

5. Standardization of processes and procedures, and improvements in Peru’s mining units contingency plans

 

6. Team training and awareness

 

7. Synergy with Digital Mining actions measures

 

8. Industrial Automation Master Plan

 

At the time of this writing, site-specific information for OHS plans and operations at Cerro Lindo were unavailable for review. Recently, the total recordable injury frequency rate has varied between 2.05 (2015) and 4.85 (2014). In 2018, the rate was 3.59 and in 2019, the rates have varied between 2.06 and 2.61. Initiatives promoted at Cerro Lindo by Nexa since 2018 include the implementation of the Prevention of Fatalities and Critical Controls program for high risk management, leadership training in the roles of Risk Management and Influence Safety, and the first safety meeting with strategic suppliers with the aim of strengthening long term relationships and effective communication.

 

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Corporately, Nexa has stated its commitment to internationally recognized human rights and prohibits any violation of human rights in its operations and suppliers. Suppliers are asked to provide information regarding both social responsibility and human rights preservation. Nexa reported that in 2018 and 2019, there were no complaints of non-compliance with any requirements related to human rights impacts, across all of its operations.

 

There are procedures in place for employees and contractors to report grievances and ethical violations, including directly to management, via telephone and online. At the time of this writing, there were no specific reports on the number of grievances or ethical violations relevant to Cerro Lindo.

 

There are two scheduled shifts (day and night) and three rotations (five shifts on, two shifts off; nine shifts on, five shifts off; and 14 shifts on, seven shifts off). This provides staff with sufficient opportunities to rest between scheduled work activities. Nexa has tried to hire from the local workforce when possible, both for skilled and unskilled workers. Outreach is conducted to the local community through social and employment programs. Nexa has established a commitment with the Chavín and Valle de Topará communities to hire up to 25% of qualified personnel and up to 75% of labourers and sub-contractors as long as the mine operation conditions and the availability of local workforce make it possible. Hiring of local workforce is dependent on skills required by the mine operation, some of which are addressed through training programs.

 

Employees have access to a number of benefits including paid vacations and holidays, financial bonuses, health, education, overtime, living allowance, and other employment bonuses.

 

17.4.4 Community Health and Safety

 

Corporately, Nexa has made several commitments to improve community health and safety, as well as the overall well-being of community members. The general area already experiences poor water quality, which can affect human health through the transmission of disease. In the EIA for the expansion and additional installations at Cerro Lindo, it was concluded that the project’s air, noise, and vibration effects were insignificant and would not cause any increased public health effects in nearby communities. Despite this, the impact assessment raised the potential for negative perceptions of health effects at various stages of the project, including perceived impacts to water quality and respiratory illnesses. To mitigate this, the assessment recommends ongoing communication to raise awareness and inform the public of project impacts. It is anticipated that any negative perception will decrease over time.

 

The impact assessment also describes health promotion activities to improve community health and safety, outside of direct project effects. This includes a program to improve dental care in the areas of direct social influence.

 

Nexa has also committed resources to improving overall community health, safety, and well-being for the communities in the areas of influence of the Cerro Lindo Mine. These ongoing activities include:

 

1. Organic Agriculture and Irrigation Project

 

2. Safe Water Project

 

3. Local Supply Project

 

4. Women Leaders Network Project

 

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5. Local Training and Employability Project

 

6. Local Scholarship Project

 

Nexa has also undertaken several municipal improvements in the nearby communities including drinking water infrastructure, waste water infrastructure, and roads and transportation improvements. Nexa also encourages its employees and community members to participate in volunteer initiatives such as Christmas shows, gender equity, and equal opportunity workshops, recycling programs, and various educational programs.

 

The 2016 annual report from Milpo describes community participation in ongoing environmental and water quality monitoring. These programs allow for community members to learn about the Cerro Lindo Mine environmental performance as well as receive training. Nexa has continued with this participatory monitoring for water quality.

 

Collectively, these programs seek to improve local socio-economic conditions and support a more diverse and educated workforce.

 

In December of 2019, community members of Chavin and Valle de Topará interrupted the mine access road for two days alleging non-compliance with the agreement and addenda related to environmental contamination. In response to the road blockage, a roundtable discussion took place with participation of the General Social Management office of the Ministry of Energy and Mines. Cerro Lindo provided information during the discussions to demonstrate compliance with agreements and absence of signs of contamination. A coordination effort was initiated to strengthen community training on environmental matters and organize information meetings to make more transparent and facilitate the communication between the community and the mining company.

 

The EIA concluded that there would be one negative environmental effect on the social environment. During the construction and operation and maintenance stages of the project, job expectations from the local community may exceed the number and type of new jobs available. This impact was found to be moderately significant for both stages of the Project. In order to mitigate these impacts, the assessment recommends ongoing communication with the community and sharing of information on project phases, impacts, and economic opportunities as detailed in the Environmental Management Strategy.

 

The EIA also identifies positive benefits for the nearby communities. Continuation with the social programs and activities was determined to be a moderately significant contributor to positive impacts.

 

17.4.5 Land Acquisition and Involuntary Resettlement

 

The proposed expansion and additional installations at Cerro Lindo will not require any resettlement of the population as all work will be completed in the existing industrial area of the Mine. Therefore, PS5 is not applicable.

 

17.4.6 Indigenous Peoples

 

Prior to 2020 Nexa informed SLR that the Cerro Lindo operations are not located on Indigenous or immediately adjacent lands. Accordingly, PS7 was not considered applicable before. In 2020 the Peruvian Ministry of Culture stipulated the incorporation of some rural communities (Comunidades Campesinas) to the official national database of Indigenous Peoples according to the results of the national census completed in 2017. The categorization was conducted based on specific criteria set out in the current legislation to identify Indigenous Peoples (i.e., historic continuity, connection with the land, distinctive institutions, and Indigenous identity). Hence, there are rural communities that could also be identified as Indigenous groups according to the identification criteria. The community of Chavin is included in the list of rural communities added to the Indigenous Peoples database in June 2020 (belongs to the Quechuas Indigenous group).

 

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No Indigenous studies have been carried out by Nexa related to the Cerro Lindo operations. SLR recommends that Nexa confirm the basis for the community of Chavin’s categorization by the Ministry of Culture and conduct a gap analysis with respect to its 2018 impact assessment studies to determine the need for additional socio-cultural studies focused on Indigenous Peoples. The categorization of the community of Chavin by the Ministry of Culture should be explicitly acknowledged in Nexa’s Social Management Plan and its sub-plans (Communications Plan, Social Concertation Plan, and Community Development Plan) modified accordingly.

 

17.4.7 Cultural Heritage

 

The EIA for the proposed expansion and additional installations at Cerro Lindo concluded that there was no presence of archaeological remains or evidence in the mine operation related areas. At the time of this writing, no information was available on Chance Find Procedures, which might be applicable as the proposed expansion undergoes construction and expanded operations commence.

 

17.5 Mine Closure Requirements

 

17.5.1 Mine Closure Plan and Regulatory Requirements

 

A formal Mine Closure Plan was prepared in 2009 for the mine components within the context of the Peruvian legislation and has subsequently been amended or updated four times. The Closure Plan addresses temporary, progressive and final closure actions, and post-closure inspection and monitoring. Under Article 20 of the Peruvian mine closure regulations, the first update of the Closure Plan must be submitted to the Peruvian Ministry of Energy and Mines (the Ministry) three years after approval of the initial Closure Plan, and every five years thereafter. Two years before final closure, a detailed version of the Mine Closure Plan will have to be prepared and submitted to the Ministry for review and approval. The following is a summary of the Cerro Lindo Mine Closure Plan updates to date:

 

Initial Closure Plan from 2009 approved by R.D. No. 326-2009-MEM/AAM, which incorporated closure measures for the components approved in the 2004 EIA under R.D. No. 325-2004/MEM/AAM.

 

First amendment of the Closure Plan from 2012 approved by R.D. No. 432-2012-MEM-AAM, which addressed operational changes approved in the 2010 EIA under R.D. No. 168-2010-MEM/AAM for the production expansion to 10,000 tpd, and the subsequent EIA modification approved in 2011 under R.D. No. 239-2011-MEM/AAM.

 

Update to the Closure Plan from 2012 approved by R.D. No. 084-2013-MEM/AAM in compliance with D.S. No. 033-2005-EM, which addressed a modification of the beneficiation concession for the production expansion to 14,990 tpd (R.D. No. 298-2011-MEM-DGM/V).

 

Second Closure Plan amendment from 2016 approved by R.D. No. 287-2016-MEM-DGAAM, which addressed the operational changes included in the supporting technical assessment reports approved under R.D. No. 069-2014-MEM-DGAAM (expansion to 10,000 tpd) and R.D. No. 391-2014-MEM-AAM (expansion to 17,988 tpd). Under article 2 of R.D. 287-2016-MEM-DGAAM, an annual financial assurance must be provided to the Ministry, using estimation factors set out by the Ministry.

 

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Third Closure Plan amendment from 2019 prepared to address mine facilities and operational changes associated with the production expansion to 22,500 tpd as approved in the modification of the EIA completed in 2018. The Third Amendment to the Mine Closure Plan is under review and approval process by the Peruvian Authorities.

 

The 2008 Mine Closure Plan (Knight Piésold, 2008), the 2016 Mine Closure Plan (Geoservice Ingeniería, 2016), the conceptual closure plan included in the 2018 EIA (SRK, 2018) and the 2019 Mine Closure Plan (KCB, 2019) were available for review.

 

The approved period for implementing closure and post-closure in the initial Mine Closure Plan was 18 years. Post-closure monitoring, assumed to extend for five years after closure, will include monitoring of physical, geochemical, hydrological, biological, and social stability.

 

The specific objectives of the Cerro Lindo Mine Closure Plan are as follows:

 

Health and safety – The closure activities should substantially eliminate or reduce the risks associated with public health and safety within the mine site area. In the event of residual risks, appropriate controls must be implemented to minimize the exposure. The closure activities should guarantee the health and safety of the workers.

 

Physical stability – Identify and evaluate technical and environmental measures to maintain the physical stability of mine components in the short and long term (for example, resilience against seismic events and extreme hydrologic events).

 

Geochemical stability – Long term closure design and measures to prevent acid rock drainage and/or metal leaching that could impact natural water bodies in compliance with requirements of the Peruvian environmental legislation related to effluents from mine facilities. The closure measures must protect human health and prevent migration of mine effluents that are not in compliance with the national legislation requirements.

 

Land use – Consider possible uses of the mine site area during post-closure for agricultural, recreational, and touristic activities given the availability of water supply and distribution system and re-vegetated areas following mine closure.

 

Water body use – Prevent degradation of water quality and reduction of water quantity of water bodies taking into consideration the existing conditions of receiving water bodies as the referential baseline.

 

Social objectives – Develop social programs for post-closure that mitigate social effects resulting from cessation of mine operations. Measures to mitigate socio-economic effects should be addressed during the mine life. The program for community development should reinforce skills development and sustainable projects without mine support to the extent feasible. The closure plan should be aligned with local land uses and development objectives.

 

Other – Implement closure activities aimed to passive care where active treatment, maintenance, and monitoring are not required in the long term.

 

In general, closure activities include mobilization of equipment, machinery and personnel; physical, geochemical and hydrological stabilization; dismantling of surface components; demolition, removal and disposal; and levelling and contouring of ground surface. Waste materials will be decontaminated (if required), recycled when cost effective, and disposed of at a licensed facility. Facilities containing petroleum products, chemicals, solid waste, hazardous waste, and/or contaminated soil or materials will be dismantled and managed according to regulatory requirements. All hazardous waste will need to be managed according to existing laws and regulations and will be transported off site.

 

Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
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The geographical area where the Cerro Lindo facilities are located is arid, characterized by very low precipitation and high evaporation. Development of vegetation is difficult in these conditions. Accordingly, no re-vegetation of the disturbed areas is proposed although a topsoil layer will be placed at closure. Rehabilitation of the aquatic habitat is not proposed either since no detrimental effects on the aquatic environment are anticipated as a result of mine operations and closure.

 

A summary of the main proposed closure activities is presented in Table 17-3.

 

Table 17-3:           Summary of Main Closure Activities 

Nexa Resources S.A. – Cerro Lindo Mine

 

Mine Component   Closure Activities
Mine   Underground mine (portals, shafts and drilling platforms)   Dismantling and removal of equipment 
Installation of concrete plugs (stability of crown pillars must be assured) and backfilling with waste rock between the plugs and the exit points 
Recontouring of terrain at ground surface level to match original surface and promote adequate natural drainage Placing of topsoil
Waste disposal facilities   Waste dumps (Pahuaypite, No. 1, No. 2, No. 7, and No. 100) 
Temporary ore stockpile 
Landfills
  Contouring of slope (physical stability) 
Installation of low permeability cover on waste rock dumps to limit infiltration 
Preservation of existing perimeter channels for management of surface runoff 
Construction of drainage channels 
Compaction and neutralization of landfill with lime
 
 
  TSFs   
(Pahuaypite 1 and 2)
  Levelling and recontouring 
Installation of low permeability cover to limit infiltration 
Construction of drainage channels 
Removal of geosynthetic materials and demolition of concrete structures from water management (contingency) ponds 
Partial backfilling of water management (contingency) ponds with inert materials to achieve surface with stable slopes
Other infrastructure   Process plant 
Conveyors 
Tailings filter plant 
Paste backfill plant 
Water management infrastructure 
Shops 
Transmission lines and electrical substations 
  De-energization and cleaning 
Removal of equipment 
Dismantling, demolition, salvaging, and disposal of structures 
Demolition of concrete structures 
Transportation to authorized disposal or collection areas 
Recontouring of terrain and placement of ground cover layer typical of the mine site area 
Implementation of natural drainage and/or construction of drainage channels as applicable 
Removal of contaminated soils 

 

Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
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Mine Component   Closure Activities
    Warehouse and auxiliary buildings 
Laydown areas 
Access roads 
Desalination plant
  Cleaning and purification of tanks and deposits
Staff facilities   Mine camp 
Administrative buildings 
Potable water and sewage systems
  Dismantling and removal of structures and equipment to authorized disposal areas 
Removal of prefabricated elements 
Demolition of concrete slabs 
Recontouring of terrain and placement of ground cover layer typical of the mine site area 
Implementation of natural drainage

 

Physical, chemical, biological, and social stability conditions following closure will be verified through implementation of the post-closure maintenance and monitoring program. Monitoring will also support the evaluation and verification of compliance with closure activities, and the identification of deviations leading to the adoption of corrective measures. The monitoring activities will be carried out considering the Peruvian Environmental Quality Standards and Maximum Permissible Limits, as well as criteria set in the Mine Closure Plan for physical, chemical, biological, and social stability.

 

Post-closure maintenance activities mainly involve the development and implementation of inspection programs, and the execution of physical repair activities of mine closure infrastructure as required (for example, repairs to low permeability covers and drainage system).

 

Post-closure monitoring activities involve the following:

 

Physical – Inspection of mine facilities, mainly the waste rock dumps to identify cracking, displacements, and settlements on slopes; the monitoring frequency will be biannually for five years.

 

Geochemical – Surface water quality monitoring in natural water bodies and receiving water bodies in order to evaluate the effectiveness of the measures established; inspection of low permeability covers; the monitoring frequency will be biannually for five years.

 

Hydrological – Technical inspections of the drainage systems to identify possible erosion, settlement, collapses and obstructions; the monitoring frequency will be biannually for five years.

 

Biological – Monitoring of terrestrial and aquatic biota in the surrounding areas of locations of mine components as a reference to verify biological conditions in non-disturbed areas, which are considered areas of control; the monitoring frequency will be biannually for five years (dry and wet season).

 

Social – Development of a set of actions that will allow to verify the efficiency and effectiveness of the social programs at mine closure in accordance with established objectives, and adoption of corrective measures as required.

 

Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
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17.5.2 Closure Cost Estimate and Financial Assurance for Closure

 

A closure cost estimate was developed and included in the Mine Closure Plans. The total value estimated in 2019 for the remaining life of mine presented in the third modification of the Mine Closure Plan is as follows (excluding local taxes):

 

Progressive Closure (2021 to 2027) US$16,722,702

 

Final Closure (2028 and 2029) US$39,504,100

 

Post-Closure (2030 to 2034) US$     930,170

 

According to Supreme Decree D.S. N° 262-2012-MEM/DM, the financial assurance is calculated based on inflation and discount rates in order to estimate the net present value for the mine closure cost. The total financial assurance (progressive closure, final closure and post-closure) has been calculated in 2019 considering an inflation rate of 2.37% and a discount rate of 2.14% resulting in a total of US$57,128,936 (including local taxes).

 

Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
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18.0 Capital and Operating Costs

 

SLR reviewed capital and operating costs required for mining and processing of Mineral Reserves at Cerro Lindo. Costs were supplied to SLR by Nexa. Cerro Lindo is an operating mine, therefore, capital and operating cost estimates were prepared based on recent operating performance and the current operating budget for 2020. SLR considers these cost estimates to be reasonable, provided the production targets are realized. All costs in this section are expressed in Q4 2020 US dollars.

 

In both cases, capital and operating cost estimates are based on recent estimates and actual costs and considered by SLR to be reasonable.

 

18.1 Capital Costs

 

The capital costs for the Cerro Lindo LOM period are shown in Table 18-1. The Mine is a current producer, therefore there are no pre-production capital costs. The other sustaining capital costs shown are for ventilation and cooling, electrical substations, and accessories. The heavy equipment replacement costs carry on until 2027.

 

Table 18-1:           Sustaining Capital Cost 

Nexa Resources S.A. – Cerro Lindo Mine

 

Description   Total (US$000)   2021   2022   2023   2024   2025   2026   2027   2028   2029   2030
Mine Development   66,275   20,326   16,768   15,903   3,722   9,556   -   -   -   -   -
Equipment Replacement   32,410   3,744   5,136   5,195   8,860   6,651   2,824   -   -   -   -
Other Sustaining   37,547   8,649   6,630   (492)   7,737   3,096   1,910   3,339   3,339   3,339   -
Tailings / Dumps   9,246   3,082   664   5,500   -   -   -   -   -   -   -
Modernization   9,364   3,760   4,779   525   205   95   -   -   -   -   -
Sub-Total   154,842   39,561   33,977   26,631   20,524   19,398   4,734   3,339   3,339   3,339   -
Closure   57,157   -   -   -   -   -   -   -   -   -   57,157
Total   211,999   39,561   33,977   26,631   20,524   19,398   4,734   3,339   3,339   3,339   57,157

 

The mine closure plan engineering design was prepared to meet the Peruvian national requirements with the closure and reclamation cost assessed at $57.2 million with the distribution as indicated. The closure cost should be updated regularly to address changes and updates in the national requirements.

 

18.2 Operating Costs

 

A summary of the LOM operating costs is shown in Table 18-2.

 

Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
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Table 18-2:           Mine Operating Cost Estimate 

Nexa Resources S.A. – Cerro Lindo Mine

 

Description   Total LOM
(US$M)
  Average
(US$M/yr)
  LOM Unit Cost
(US$/t)
UG Mining   791   88   15.18
Mine Development   231   26   4.44
Processing   623   69   11.95
G&A   157   17   3.01
Total   1,802   200   34.58

 

The average operating cost is based on a LOM period of nine years from 2021 through 2029. The operating cost inputs including labour, consumables, and supplies were based on data supplied by Nexa.

 

The operating cost profile, showing actuals for 2017 to 2019 and the LOM period, is shown in Figure 18-1.

 

 

 

Figure 18-1:           Operating Cost Profile

 

From 2025 onwards, the mine production falls to approximately 60% of the previous years as mining will take place close to the primary underground crusher location thereby negating use of the crusher. Transportation costs will consequently increase. The lower productivity is reflected in higher mining unit costs as indicated.

 

18.2.1 Manpower

 

The manpower breakdown and contractors list for the entire operation at Cerro Lindo are shown in Table 18-3 and Table 18-4, respectively. Cerro Lindo has historically used a significant amount of contract services. The number of contractors on site varies depending on the requirements of the mine. Table 18-4 shows the number of contractors employed for December 2020.

 

Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
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Table 18-3:          Manpower Distribution 

Nexa Resources S.A. – Cerro Lindo Mine

 

Area   Managers   General Staff   Operators & Technical Staff   Total
Human Resources       10   4   14
Geology and Exploration   1   9   15   25
Unit Management   1   8       9
Management   1           1
Infrastructure   1   3   3   7
Maintenance   1   23   77   101
Environment       3   6   9
Mine   1   29   206   236
Plant   1   16   91   108
Projects   1   7       8
Community Relations       4       4
Security   1   11   2   14
Technical Services   1   24   32   57
Support Staff       6   9   15
Total   10   153   445   608

 

Table 18-4:           Contractors List - December 2020 

Nexa Resources S.A. – Cerro Lindo Mine

 

Contractor   Area   Shift   Number
Manpower Peru   Admin & Community Relations   14 x 7   5
Explosupport S.A.C.   Exploration   14 x 7   1
Certimin S.A.   Geology   14 x 7   17
Explomin Del Peru S.A.   Geology   14 x 7   139
Newrest Peru S.A.C.   Human Resources   14 x 7   231
Movil Bus S.A.   Infrastructure   14 x 7   16
Proseguridad S.A.   Infrastructure   14 x 7   45
Sodexo Peru S.A.C.   Infrastructure   28 x 14   32
Transportes San Alejandro S.A.C.   Logistics   14 x 7
6 x 1
  36
Atlas Copco Peruana S.A.   Maintenance   14 x 7   3
Cana Dyne Equipment and Services S.A.   Maintenance   14 x 7   13

 

Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
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Contractor   Area   Shift   Number
Confipetrol Andina S.A.   Maintenance   14 x 7   284
Distribuidora De Mangueras Hidraulicas S.A.C.   Maintenance   14 x 7   6
Epiroc Peru S.A.   Maintenance   14 x 7   31
Ferreyros S.A.   Maintenance   14 x 7   16
Industrias Islas   Maintenance   5 x 2
8 x6
  17
Mb Renting   Maintenance   14 x 7   10
Sandvik Del Peru S.A.   Maintenance   14 x 7   17
Grupo Alvarado S.A.C.   Maintenance   14 x 7   2
Administracion De Empresas S.A.C.   Mine   14 x 7   390
American Renta Car S.A.C.   Mine   14 x 7   53
Dinet S.A.   Mine   14 x 7   267
Exsa S.A.   Mine   14 x 7   57
Incimmet S.A.   Mine   14 x 7   298
Tumi Contratistas Mineros S.A.C.   Mine   14 x 7   66
Union De Concreteras S.A.   Mine   14 x 7   126
Etranserge S.R.L.   Plant   14 x 7   42
Ecoserm - Chavin   Security/ Environment/ Infrastructure   14 x 7   113
Salus Laboris S.A.C.   Security   14 x 14   10
Sgs Del Peru Sac   Security/ Environment/ Infrastructure   10 x 4   3
Transporte Minero Za E.I.R.L.   Security/ Environment/ Infrastructure   14 x 7   20
Ulloa S.A.   Security/ Environment/ Infrastructure   14 x 7   22
Total           2,388

 

Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
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19.0 Economic Analysis

 

The economic analysis contained in this Technical Report Summary is based on the Mineral Reserves, economic assumptions provided by Nexa, and the capital and operating costs as presented in Section 18 of this Technical Report Summary.

 

Nexa has a silver streaming agreement with Triple Flag on silver production from the Cerro Lindo Mine. Triple Flag has the rights to 65% of all payable silver, at a cost of 10% of the spot silver price (up to a total of 19.5 Moz Ag). After the total has been reached, currently anticipated to be 2027, Triple Flag is entitled to 25% of payable silver.

 

19.1 Economic Criteria

 

19.1.1 Physicals

 

Mine life: 9 years (between 2021 and 2029):

 

Underground Ore tonnes mined: 52,101 kt

 

o Cu grade: 0.61%

 

o Zn grade: 1.44%

 

o Pb grade: 0.20%

 

o Ag grade: 21.2 g/t

 

Processed:

 

o Total Ore Feed: 52,101 kt

 

Cu grade: 0.61%

 

Zn grade: 1.44%

 

Pb grade: 0.20%

 

Ag grade: 21.2 g/t

 

o Contained Metal:

 

Cu: 319 kt

 

Zn: 748 kt

 

Pb: 106 kt

 

Ag: 35,472 koz

 

o Average LOM Recoveries:

 

Cu recovery 86.9%

 

Zn recovery 88.3%

 

Pb recovery 70.0%

 

Ag in Cu recovery 39.9%

 

Ag in Zn recovery 6.0%

 

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Ag in Pb recovery 28.9%

 

o Recovered Metals:

 

Cu: 277 kt

 

Zn: 660 kt

 

Pb: 74 kt

 

Ag: 26,527 koz

 

o Payable Metals:

 

Cu: 266.7 kt

 

Zn: 561.2 kt

 

Pb: 70.6 kt

 

Ag: 22,446 koz

 

19.1.2 Revenue

 

Revenue is estimated based on the following LOM weighted average metal prices:

 

o Cu price: US$6,458/t

 

o Zn price: US$2,487/t

 

o Pb price: US$1,987/t

 

o Ag price - spot: US$17.01/oz

 

Net Revenue includes the benefit of Cerro Lindo’s zinc concentrate processed at Nexa’s Cajamarquilla (CJM) zinc refinery in Peru (61%) and Três Marias (TM) (35%) and Juiz de Fora (JF) (4%) zinc refineries in Brazil. This integration with Nexa’s internal refineries provides the benefit of additional US$150.34/t zinc selling price in average, and zinc smelting at cost (rather than at commercial third-party terms).

 

Logistics, Treatment and Refining charges:

 

o LOM average Transportation/Logistics charges:

 

Cu concentrate: US$109.26/t concentrate

 

Zn concentrate: US$64.82/t concentrate (weighted average logistic integration cost with CJM, TM, and JF refineries)

 

Pb concentrate: US$108.75/t concentrate

 

o Treatment Charges:

 

TC+RC Cu concentrate: US$112.35/t concentrate

 

TC Zn concentrate for export: US$238.91/t concentrate

 

TC Pb concentrate: US$201.16/t concentrate

 

Refined Zn weighted average conversion costs at CJM, TM, and JF refineries: US$443.10/t

 

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o Refining Charges:

 

Ag in Cu concentrate: US$0.50/oz

 

Ag in Pb concentrate: US$1.00/oz

 

NSR Revenue after Logistics, Treatment and Refining charges is US$3,076 million.

 

19.1.3 Capital Costs

 

LOM sustaining capital costs of US$154.8 million.

 

LOM working capital balance of US$117.7 million.

 

Closure costs of US$57.2 million were included at the end of the Mineral Reserves based LOM in year 2030.

 

19.1.4 Operating Costs

 

LOM unit operating cost average of:

 

o Mine Development: US$4.44/t mined

 

o Underground Mining: US$15.18/t mined

 

o Processing: US$11.95/t milled

 

o G&A: US$3.01/t milled

 

Total unit operating costs of US$34.58/t milled.

 

LOM operating costs of US$1,801 million.

 

19.1.5 Taxation and Royalties

 

Corporate income tax rate in Peru is 29.50%.

 

Special Mining Tax (IEM/GEM) LOM average rate: 4.3%.

 

Mining royalties LOM average rate: 4.3%.

 

Employees participation: 8%.

 

SLR has relied on a Nexa taxation model for calculation of income taxes applicable to the cash flow.

 

19.2 Cash Flow

 

SLR developed a LOM after-tax cash flow model for the Cerro Lindo Mine to confirm the economics of the LOM plan. The model is based on Nexa’s TR Cerro Lindo 2020 Final2 model. The model does not take into account the following components:

 

Financing costs

 

Insurance

 

Overhead cost for a corporate office

 

A cash flow summary is presented in Table 19-1. All costs are in Q4 2020 US dollars with no allowance for inflation.

 

Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
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Table 19-1:           After-Tax Cash Flow Summary

Nexa Resources S.A. - Cerro Lindo Mine

  

    INPUTS   UNITS   TOTAL   2021
Year 1
  2022
Year 2
  2023
Year 3
  2024
Year 4
  2025
Year 5
  2026
Year 6
  2027
Year 7
  2028
Year 8
  2029
Year 9
  2030
Year 10
MINING                                                    
Underground                                                    
Operating Days   365   days   3,285   365   365   365   365   365   365   365   365   365    
Tonnes milled per day       tonnes / day   15,860   19,178   19,178   17,808   17,808   13,699   13,699   13,699   13,699   13,976    
Production       '000 tonnes   52,101   7,000   7,000   6,500   6,500   5,000   5,000   5,000   5,000   5,101    
Ag Grade       oz/t   0.68   0.61   0.71   0.78   0.74   0.90   0.61   0.56   0.63   0.57    
Cu Grade       %   0.61%   0.44%   0.48%   0.52%   0.59%   0.75%   0.68%   0.73%   0.73%   0.75%    
Pb Grade       %   0.20%   0.23%   0.25%   0.26%   0.22%   0.28%   0.18%   0.13%   0.13%   0.10%    
Zn Grade       %   1.44%   1.77%   1.56%   1.50%   1.38%   1.70%   1.51%   1.34%   1.12%   0.87%    
Waste       '000 tonnes   -   -   -   -   -   -   -   -   -   -    
Total Moved      

'000 tonnes

  52,101   7,000   7,000   6,500   6,500   5,000   5,000   5,000   5,000   5,101    
PROCESSING                                                    
Mill Feed       '000 tonnes   52,101   7,000   7,000   6,500   6,500   5,000   5,000   5,000   5,000   5,101    
Au Grade       oz/t   -   -   -   -   -   -   -   -   -   -    
Ag Grade       oz/t   0.68   0.61   0.71   0.78   0.74   0.90   0.61   0.56   0.63   0.57    
Cu Grade       %   0.61%   0.44%   0.48%   0.52%   0.59%   0.75%   0.68%   0.73%   0.73%   0.75%    
Pb Grade       %   0.20%   0.23%   0.25%   0.26%   0.22%   0.28%   0.18%   0.13%   0.13%   0.10%    
Zn Grade       %   1.44%   1.77%   1.56%   1.50%   1.38%   1.70%   1.51%   1.34%   1.12%   0.87%    
Contained Au       oz   -   -   -   -   -   -   -   -   -   -    
Contained Ag       oz   35,471,739   4,273,185   4,974,134   5,042,177   4,806,717   4,486,838   3,025,077   2,804,072   3,133,926   2,925,613    
Contained Cu       tonnes   319,137   31,023   33,609   33,643   38,349   37,479   34,000   36,261   36,661   38,113    
Contained Pb       tonnes   106,140   15,924   17,704   17,218   14,514   14,026   8,898   6,322   6,455   5,079    
Contained Zn       tonnes   747,899   123,900   109,030   97,500   89,600   85,000   75,461   67,224   55,967   44,217    
Recovery Grade                                                    
Cu Concentrate   Recovery #1   %                                            
Au           0%   0%   0%   0%   0%   0%   0%   0%   0%   0%    
Ag           39.87%   40%   40%   40%   40%   40%   40%   40%   40%   40%    
Cu           86.9%   82%   83%   84%   90%   89%   88%   88%   88%   88%    
Pb           0%   0%   0%   0%   0%   0%   0%   0%   0%   0%    
Zn           0%   0%   0%   0%   0%   0%   0%   0%   0%   0%    
Pb Concentrate   Recovery #2   %                                            
Au           0%   0%   0%   0%   0%   0%   0%   0%   0%   0%    
Ag           28.9%   29%   29%   29%   29%   29%   29%   29%   29%   29%    
Cu           0%   0%   0%   0%   0%   0%   0%   0%   0%   0%    
Pb           70.0%   71%   73%   74%   71%   75%   67%   61%   61%   58%    
Zn   0%       0%   0%   0%   0%   0%   0%   0%   0%   0%   0%    
Zn Concentrate   Recovery #3   %                                            
Au           0%   0%   0%   0%   0%   0%   0%   0%   0%   0%    
Ag   9%       6.00%   6%   6%   6%   6%   6%   6%   6%   6%   6%    
Cu           0%   0%   0%   0%   0%   0%   0%   0%   0%   0%    
Pb           0%   0%   0%   0%   0%   0%   0%   0%   0%   0%    
Zn           88.3%   90%   89%   88%   88%   89%   88%   88%   86%   85%    
Net Recovery       %                                            
Au           0.0%   0%   0%   0%   0%   0%   0%   0%   0%   0%    
Ag           74.8%   75%   75%   75%   75%   75%   75%   75%   75%   75%    
Cu           86.9%   82%   83%   84%   90%   89%   88%   88%   88%   88%    
Pb           70.0%   71%   73%   74%   71%   75%   67%   61%   61%   58%    
Zn           88.3%   90%   89%   88%   88%   89%   88%   88%   86%   85%    
Total Average Recovery           75.2%   75%   75%   75%   75%   75%   75%   75%   75%   75%    
Recovered Amount                                                    
Cu Concentrate   Recovery #1                                                
Au       oz   -   -   -   -   -   -   -   -   -   -    
Ag       oz   14,143,620   1,703,844   1,983,333   2,010,463   1,916,579   1,789,034   1,206,187   1,118,065   1,249,588   1,166,527    
Cu       tonnes   1,071,157   98,158   108,141   109,583   133,689   128,073   114,886   123,458   124,976   130,192    
Pb       tonnes   -   -   -   -   -   -   -   -   -   -    
Zn       tonnes   -   -   -   -   -   -   -   -   -   -    
Pb Concentrate   Recovery #2                                                
Au       oz   -   -   -   -   -   -   -   -   -   -    
Ag       oz   10,254,876   1,235,377   1,438,022   1,457,693   1,389,621   1,297,145   874,549   810,657   906,018   845,794    
Cu       tonnes   -   -   -   -   -   -   -   -   -   -    
Pb       tonnes   116,434   17,698   20,219   19,893   16,053   16,433   9,274   6,049   6,208   4,607    
Zn       tonnes   -   -   -   -   -   -   -   -   -   -    
Zn Concentrate   Recovery #3                                                
Au       oz   -   -   -   -   -   -   -   -   -   -    
Ag       oz   2,128,304   256,391   298,448   302,531   288,403   269,210   181,505   168,244   188,036   175,537    
Cu       tonnes   -   -   -   -   -   -   -   -   -   -    
Pb       tonnes   -   -   -   -   -   -   -   -   -   -    
Zn       tonnes   1,121,767   188,863   164,355   146,497   133,662   129,111   113,442   100,074   82,094   63,669    
Grades in Concentrate                                                    
Cu Concentrate       dmt   1,071,157   98,158   108,141   109,583   133,689   128,073   114,886   123,458   124,976   130,192    
Au grade in concentrate       oz/t   -   -   -   -   -   -   -   -   -   -    
Ag grade in concentrate       oz/t   13.20   17.36   18.34   18.35   14.34   13.97   10.50   9.06   10.00   8.96    
Cu grade in concentrate   25.9%   %   25.90%   26%   26%   26%   26%   26%   26%   26%   26%   26%    
Pb grade in concentrate       %   0.00%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%    
Zn grade in concentrate       %   0.00%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%    
Concentrate Moisture   0%           0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%    
Cu Concentrate       wmt   1,071,157   98,158   108,141   109,583   133,689   128,073   114,886   123,458   124,976   130,192    

 

Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
Technical Report Summary - January 29, 2021
  19-4  

 

 

 

 

    INPUTS   UNITS   TOTAL   2021
Year 1
  2022
Year 2
  2023
Year 3
  2024
Year 4
  2025
Year 5
  2026
Year 6
  2027
Year 7
  2028
Year 8
  2029
Year 9
  2030
Year 10
Pb Concentrate       dmt   116,434   17,698   20,219   19,893   16,053   16,433   9,274   6,049   6,208   4,607    
Au grade in concentrate       oz/t   -   -   -   -   -   -   -   -   -   -    
Ag grade in concentrate       oz/t   88.07   69.80   71   73   87   79   94   134   146   184    
Cu grade in concentrate       %   0.00%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%    
Pb grade in concentrate   63.82%   %   63.82%   63.82%   63.82%   63.82%   63.82%   63.82%   63.82%   63.82%   63.82%   63.8%    
Zn grade in concentrate       %   0.00%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%    
Concentrate Moisture   0%           0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%    
Pb Concentrate       wmt   116,434   17,698   20,219   19,893   16,053   16,433   9,274   6,049   6,208   4,607    
Zn Concentrate       dmt   1,121,767   188,863   164,355   146,497   133,662   129,111   113,442   100,074   82,094   63,669    
Au grade in concentrate       oz/t   -   -   -   -   -   -   -   -   -   -    
Ag grade in concentrate       oz/t   1.90   1.36   1.82   2.07   2.16   2.09   1.60   1.68   2.29   2.76    
Cu grade in concentrate       %   0.00%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%    
Pb grade in concentrate       %   0.00%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%    
Zn grade in concentrate   58.86%   %   58.86%   59%   59%   59%   59%   59%   59%   59%   59%   59%    
Concentrate Moisture   0%           0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%    
Zn Concentrate       wmt   1,121,767   188,863   164,355   146,497   133,662   129,111   113,442   100,074   82,094   63,669    
Total Tonnes Concentrate       wmt   2,309,357   304,719   292,715   275,973   283,404   273,617   237,602   229,582   213,278   198,468    
Total Recovered                                                    
Au       oz   -   -   -   -   -   -   -   -   -   -    
Ag       oz   26,526,801   3,195,612   3,719,802   3,770,687   3,594,603   3,355,389   2,262,241   2,096,967   2,343,642   2,187,859    
Cu       tonnes   277,430   25,423   28,009   28,382   34,625   33,171   29,755   31,976   32,369   33,720    
Pb       tonnes   74,308   11,295   12,904   12,696   10,245   10,488   5,919   3,861   3,962   2,940    
Zn       tonnes   660,272   111,165   96,739   86,228   78,673   75,995   66,772   58,903   48,321   37,476    
                                                     
REVENUE                                                    
Metal Prices                                                    
LOM Au       US$/oz   $1,568.10   1,901   1,613   1,553   1,466   1,466   1,500   1,500   1,500   1,500    
LOM Ag       US$/oz   $17.05   19.05   17.11   16.95   16.40   16.40   16.87   16.87   16.87   16.87    
LOM Cu       US$/tonne   $6,457.72   6,071   6,137   6,277   6,351   6,639   6,627   6,627   6,627   6,627    
LOM Pb       US$/tonne   $1,987.41   1,950   1,898   1,957   2,039   2,247   1,910   1,910   1,910   1,910    
LOM Zn       US$/tonne   $2,487.33   2,219   2,298   2,539   2,720   2,928   2,449   2,449   2,449   2,449    
Au       US$/oz Au   $1,568.10   $1,901   $1,613   $1,553   $1,466   $1,466   $1,500   $1,500   $1,500   $1,500    
Ag       US$/oz Ag   $17.05   $19.05   $17.11   $16.95   $16.40   $16.40   $16.87   $16.87   $16.87   $16.87    
Cu       US$/lb Cu   $2.93   $2.75   $2.78   $2.85   $2.88   $3.01   $3.01   $3.01   $3.01   $3.01    
Pb       US$/lb Pb   $0.90   $0.88   $0.86   $0.89   $0.92   $1.02   $0.87   $0.87   $0.87   $0.87    
Zn       US$/lb Zn   $1.13   $1.01   $1.04   $1.15   $1.23   $1.33   $1.11   $1.11   $1.11   $1.11    
Exchange Rate   1.00 US$ = 1.00 C$   US$ 1.00 = X C$   $1.00   $1.00   $1.00   $1.00   $1.00   $1.00   $1.00   $1.00   $1.00   $1.00    
Concentrate Payable %                                                    
Cu Concentrate Payable %                                                    
Payable Au       %       0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%    
Payable Ag Grade       oz/t   11.86   15.62   16.51   16.51   12.90   12.57   9.45   8.06   9.00   7.96    
Payable Cu   24.90%   %       24.9%   24.9%   24.9%   24.9%   24.9%   24.9%   24.9%   24.9%   24.9%    
Pb Concentrate Payable %                                                    
Payable Au       %       0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%    
Payable Ag Grade       oz/t   83.67   66.31   67.57   69.61   82.24   74.99   89.59   127.31   138.65   174.42    
Payable Pb   60.63%   %       60.63%   60.63%   60.63%   60.63%   60.63%   60.63%   60.63%   60.63%   60.63%    
Zn Concentrate Payable %                                                    
Payable Au       %       0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%   0.0%    
Payable Ag Grade       oz/t   -   -   -   -   -   -   -   -   -        
Payable Zn       %       50.0%   50.0%   50.0%   50.0%   50.0%   50.0%   50.0%   50.0%   50.0%    
Concentrate Payable                                                    
Cu Concentrate Payables                                                    
Payable Au       oz   -   -   -   -   -   -   -   -   -   -    
Payable Ag       oz   12,704,049   1,533,459   1,784,999   1,809,417   1,724,921   1,610,130   1,085,568   994,607   1,124,612   1,036,335    
Payable Cu       tonnes   266,718   24,441   26,927   27,286   33,288   31,890   28,607   30,741   31,119   32,418    
Payable Ag       US$/t conc   185.95   297.6   282.4   279.9   211.6   206.2   159.4   135.9   151.8   134.3    
Payable Cu       US$/t conc   1,407   1,512   1,528   1,563   1,581   1,653   1,650   1,650   1,650   1,650    
Pb Concentrate Payables                                                    
Payable Au       oz   -   -   -   -   -   -   -   -   -   -    
Payable Ag       oz   9,742,133   1,173,608   1,366,121   1,384,808   1,320,140   1,232,287   830,822   770,124   860,717   803,505    
Payable Pb       tonnes   70,594   10,730   12,259   12,061   9,733   9,963   5,623   3,668   3,764   2,793    
Payable Ag       US$/t conc.   1,311   1,263   1,156   1,180   1,349   1,230   1,511   2,148   2,339   2,942    
Payable Pb       US$/t conc.   1,159   1,182   1,151   1,187   1,236   1,362   1,158   1,158   1,158   1,158    
Zn Concentrate Payables                                                    
Payable Au       oz   -   -   -   -   -   -   -   -   -   -    
Payable Ag       oz   -   -   -   -   -   -   -   -   -   -    
Payable Zn       tonnes   561,231   94,490   82,228   73,294   66,872   64,595   56,756   50,068   41,072   31,854    
Payable Ag       US$/t conc.   -   -   -   -   -   -   -   -   -   -    
Payable Zn       US$/t conc.   1,175   1,110   1,150   1,270   1,361   1,465   1,225   1,225   1,225   1,225    
Gross Revenue                                                    
Ag Stream Revenue       US$ '000   $196,913   $21,401   $22,375   $22,469   $20,725   $19,345   $17,514   $23,073   $25,957   $24,055    
Cu Gross Revenue       US$ '000   $1,722,389   $148,372   $165,252   $171,276   $211,415   $211,718   $189,576   $203,722   $206,226   $214,833    
Pb Gross Revenue       US$ '000   $140,299   $20,926   $23,267   $23,604   $19,845   $22,388   $10,740   $7,005   $7,189   $5,335    
Zn Gross Revenue       US$ '000   $1,395,966   $209,673   $188,961   $186,093   $181,893   $189,135   $138,996   $122,616   $100,586   $78,011    
Add Zn Gross Revenue - Intgr CJM       US$ '000   $262,660   $38,754   $36,156   $34,784   $33,507   $34,335   $26,929   $23,739   $19,403   $15,053    
Total Gross Revenue       US$ '000   $3,718,228   $439,127   $436,010   $438,225   $467,386   $476,922   $383,754   $380,155   $359,362   $337,287    
Total Charges                                                    
Transport                                                    
Cu Concentrate   C$109.26 / wmt conc   US$ '000   $117,038   $10,725   $11,816   $11,973   $14,607   $13,994   $12,553   $13,490   $13,655   $14,225    
Pb Concentrate   C$108.75 / wmt conc   US$ '000   $12,662   $1,925   $2,199   $2,163   $1,746   $1,787   $1,009   $658   $675   $501    
Zn Concentrate   C$64.82 / wmt conc   US$ '000   $72,713   $12,242   $10,654   $9,496   $8,664   $8,369   $7,353   $6,487   $5,321   $4,127    

 

Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
Technical Report Summary - January 29, 2021
  19-5  

 

 

    INPUTS   UNITS   TOTAL   2021
Year 1
  2022
Year 2
    2023
Year 3
  2024
Year 4
  2025
Year 5
  2026
Year 6
  2027
Year 7
  2028
Year 8
  2029
Year 9
  2030
Year 10
Treatment                                                      
Cu Concentrate   US$112.35 / dmt conc   US$ '000   $121,181   $9,121   $11,049     $11,686   $16,152   $15,077   $13,524   $14,534   $14,712   $15,326    
Pb Concentrate   US$201.16 / dmt conc   US$ '000   $23,630   $3,777   $4,206     $4,018   $3,243   $3,237   $1,827   $1,192   $1,223   $908    
Zn Concentrate   US$238.91 / dmt conc   US$ '000   $278,595   $46,108   $40,839     $36,559   $33,400   $32,352   $28,178   $24,880   $20,398   $15,880    
Refining cost                                                      
Ag in Pb   US$1.00 / oz   US$ '000   $9,710   $1,170   $1,362     $1,380   $1,316   $1,228   $828   $768   $858   $801    
Ag in Cu   US$0.50 / oz   US$ '000   $6,352   $767   $892     $905   $862   $805   $543   $497   $562   $518    
Cu   US$0.00 / lb   US$ '000   $0   $0   $0     $0   $0   $0   $0   $0   $0   $0    
Pb   US$0.00 / lb   US$ '000   $0   $0   $0     $0   $0   $0   $0   $0   $0   $0    
Market Participation                                                      
Cu   NA   US$ '000   $0   $0   $0     $0   $0   $0   $0   $0   $0   $0    
Pb   NA   US$ '000   $0   $0   $0     $0   $0   $0   $0   $0   $0   $0    
Zn   NA   US$ '000   $0   $0   $0     $0   $0   $0   $0   $0   $0   $0    
Total Charges       US$ '000   $641,882   $85,834   $83,016     $78,181   $79,990   $76,849   $65,815   $62,504   $57,405   $52,287    
Net Smelter Return       US$ '000   $3,076,346   $353,293   $352,994     $360,044   $387,396   $400,073   $317,939   $317,650   $301,956   $285,000    
Royalty NSR   Input Rate Into Proforma   US$ '000   $184,414   $11,410   $16,097     $19,062   $23,851   $33,573   $21,222   $22,699   $19,893   $16,607    
Net Revenue       US$ '000   $2,891,932   $341,882   $336,898     $340,982   $363,545   $366,500   $296,717   $294,951   $282,063   $268,394    
                               
Unit NSR       US$/t milled   $55.51   $49   $48     $52   $56   $73   $59   $59   $56   $53    
                                                       
CUT-OFF GRADE                                                      
                                                       
OPERATING COST                                                      
Mining (Underground)       US$/t milled   $15.18   $15   $15     $15   $15   $15   $15   $15   $15   $15    
Mine Development       US$/t milled   $4.44   $5.7   $5.7     $6.3   $5.3   $5.6   $3.8   $1.3   $1.8   $2.4    
Processing       US$/t milled   $11.95   $12   $12     $12   $12   $12   $12   $12   $12   $12    
G&A       US$/t milled   $3.01   $3   $3     $3   $3   $3   $3   $3   $3   $3    
Total Operating Cost       US$/t milled   $34.57   $36   $36     $36   $35   $36   $34   $31   $32   $33    
Mining (Underground)       US$ '000   $790,733   $106,238   $106,238     $98,650   $98,650   $75,884   $75,884   $75,884   $75,884   $77,420    
Mine Deveopment       US$ '000   $231,451   $40,209   $40,165     $41,158   $34,692   $27,890   $19,160   $6,631   $9,064   $12,482    
Processing       US$ '000   $622,554   $83,642   $83,642     $77,668   $77,668   $59,745   $59,745   $59,745   $59,745   $60,954    
G&A       US$ '000   $156,595   $21,039   $21,039     $19,536   $19,536   $15,028   $15,028   $15,028   $15,028   $15,332    
Total Operating Cost       US$ '000   $1,801,332   $251,129   $251,085     $237,012   $230,546   $178,546   $169,816   $157,288   $159,721   $166,189    
Unit Operating Cost       US$/t milled   $46.89   $48   $48     $48   $48   $51   $47   $44   $43   $43    
Other Costs       US$ '000   $25,170   $5,861   $5,896     $3,773   $3,335   $3,190   $3,115   $0   $0   $0    
Operating Cashflow       US$ '000   $1,065,430   $84,892   $79,917     $100,196   $129,664   $184,764   $123,786   $137,663   $122,342   $102,205    
            20.45   12.13   11.42     15.41   19.95   36.95   24.76   27.53   24.47   20.04    
CAPITAL COST                                                      
Direct Cost                                                      
Mining       US$ '000   $0   $0   $0     $0   $0   $0   $0   $0   $0   $0   $0
Processing       US$ '000   $0   $0   $0     $0   $0   $0   $0   $0   $0   $0   $0
Infrastructure       US$ '000   $9,364   $3,760   $4,779     $525   $205   $95   $0   $0   $0   $0   $0
Tailings       US$ '000   $9,246   $3,082   $664     $5,500   $0   $0   $0   $0   $0   $0   $0
Total Direct Cost       US$ '000   $18,610   $6,842   $5,443     $6,025   $205   $95   $0   $0   $0   $0   $0
Other Costs                                                      
EPCM / Owners / Indirect Cost   0%   US$ '000   $0   $0   $0     $0   $0   $0   $0   $0   $0   $0   $0
Subtotal Costs       US$ '000   $18,610   $6,842   $5,443     $6,025   $205   $95   $0   $0   $0   $0   $0
Contingency   0%   US$ '000   $0   $0   $0     $0   $0   $0   $0   $0   $0   $0   $0
Initial Capital Cost       US$ '000   $18,610   $6,842   $5,443     $6,025   $205   $95   $0   $0   $0   $0   $0
Sustaining Mine Development       US$ '000   $66,275   $20,326   $16,768     $15,903   $3,722   $9,556   $0   $0   $0   $0   $0
Mine Equipment       US$ '000   $32,410   $3,744   $5,136     $5,195   $8,860   $6,651   $2,824   $0   $0   $0   $0
Other Sustaining       US$ '000   $37,547   $8,649   $6,630     -$492   $7,737   $3,096   $1,910   $3,339   $3,339   $3,339   $0
Working Capital       US$ '000   -$117,694   -$24,316   $2,198     $3,676   $8,524   $5,953   -$21,177   -$329   -$4,327   -$4,759   -$83,138
Reclamation and closure       US$ '000   $57,157   $0   $0     $0   $0   $0   $0   $0   $0   $0   $57,157
Total Capital Cost       US$ '000   $94,306   $15,245   $36,176     $30,308   $29,047   $25,351   -$16,443   $3,011   -$988   -$1,419   -$25,981
                                                       
PRE-TAX CASH FLOW                                                      
Net Pre-Tax Cashflow       US$ '000   $971,124   $69,648   $43,741     $69,889   $100,617   $159,413   $140,230   $134,652   $123,330   $103,624   $25,981
Cumulative Pre-Tax Cashflow       US$ '000       $69,648   $113,388     $183,277   $283,894   $443,308   $583,537   $718,189   $841,519   $945,143   $971,124
Taxes - Income Tax       US$ '000   -$407,234   -$38,710   -$37,566     -$42,758   -$52,018   -$66,308   -$45,015   -$46,442   -$42,197   -$36,219   $0
Taxes - IEM/GEM       US$ '000   -$73,291   -$8,734   -$8,783     -$10,561   -$7,562   -$11,411   -$6,922   -$7,564   -$6,489   -$5,265   $0
After-Tax Cashflow       US$ '000   $490,600   $22,204   -$2,608     $16,570   $41,037   $81,695   $88,292   $80,646   $74,644   $62,140   $25,981
Cumulative After-Tax Cashflow       US$ '000       $22,204   $19,596     $36,166   $77,203   $158,897   $247,189   $327,835   $402,479   $464,618   $490,600
                                                       
PROJECT ECONOMICS           mid-year period   0.5   1.5     2.5   3.5   4.5   5.5   6.5   7.5   8.5   9.5
Pre-Tax IRR       %   N/A                                          
Pre-tax NPV at 8% discounting   8%   US$ '000   $666,534                                          
Pre-tax NPV at 9% discounting   9%   US$ '000   $638,581                                          
Pre-tax NPV at 10% discounting   10%   US$ '000   $612,341                                          
After-Tax IRR       %   N/A                                          
After-Tax NPV at 8% discounting   8%   US$ '000   $319,406                                          
After-Tax NPV at 9% discounting   9%   US$ '000   $304,001                                          
After-tax NPV at 10% discounting   10%   US$ '000   $289,527                                          

 

 

 

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19.2.1 Cash Flow Analysis

 

Mine economics have been evaluated using the discounted cash flow method, using mid-year discounting convention, and taking into account annual processed tonnages and copper, zinc, lead, and silver grades. The associated process recovery, copper, zinc, and lead concentrate grades, metal prices, operating costs, refining and transportation charges, royalties, and capital expenditures were also considered.

 

The economic analysis confirmed that the Cerro Lindo Mineral Reserves are economically viable. The pre-tax net present value (NPV) at an 9% base discount rate is US$639 million and the after-tax NPV at an 9% base discount is US$304 million.

 

The summary of the results of the cash flow analysis is presented in Table 19-2.

 

Table 19-2:                  Cash Flow Analysis

Nexa Resources S.A. – Cerro Lindo Mine

 

Item   Discount Rate   Units   Value
Pre-tax NPV at 8% discount   8%   US$ million   667
Pre-tax NPV at 9% discount   9%   US$ million   639
Pre-tax NPV at 10% discount   10%   US$ million   612
             
After-Tax NPV at 8% discount   8%   US$ million   319
After-Tax NPV at 9% discount   9%   US$ million   304
After-tax NPV at 10% discount   10%   US$ million   290

 

The undiscounted pre-tax cash flow is US$971 million, and the undiscounted after-tax cash flow is US$491 million. For this cash flow analysis, the internal rate of return (IRR) and payback are not applicable as there is no negative initial cash flow (no initial investment to be recovered).

 

19.3 Sensitivity Analysis

 

Project risks can be identified in both economic and non-economic terms. Key economic risks were examined by running cash flow sensitivities on after-tax NPV at an 9% discount rate. The following items were examined:

 

Metal prices

Head grade

Metallurgical recovery

Operating costs, and

Capital costs

 

After-tax sensitivity over the base case has been calculated for -20% to +20% (for head grade), -10% to +5% (for recoveries), -20% to +20% (for metal prices), and -5% to +15% (operating costs and capital costs) variations to determine the most sensitive parameter of this project. The sensitivities are shown in Table 19-3 and Figure 19-1.

 

Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
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Table 19-3:           After-Tax Sensitivity Analysis

Nexa Resources S.A. – Cerro Lindo Mine

 

    Head Grade   NPV at 9%
(US$ million)
80%   Cu:0.49% Zn:1.15% Pb:0.16% Ag:16.9 g/t   71
90%   Cu:0.55% Zn:1.29% Pb:0.18% Ag:19.1 g/t   188
100%   Cu:0.61% Zn:1.44% Pb:0.20% Ag:21.2 g/t   304
110%   Cu:0.67% Zn:1.58% Pb:0.22% Ag:23.3 g/t   416
120%   Cu:0.74% Zn:1.72% Pb:0.24% Ag:25.4 g/t   530

 

    Net average Recovery (all metals)   NPV at 9%
(US$ million)
90%   79%   188
98%   84%   245
100%   88%   304
103%   90%   332
105%   92%   361

 

    Metal Prices   NPV at 9%
(US$ million)
80%   Cu:$2.33/lb Zn:$0.90/lb Pb:$0.71/lb Ag:$13.68/oz   23
90%   Cu:$2.62/lb Zn:$1.02/lb Pb:$0.80/lb Ag:$15.39/oz   164
100%   Cu:$2.91/lb Zn:$1.13/lb Pb:$0.89/lb Ag:$17.10/oz   304
110%   Cu:$3.20/lb Zn:$1.24/lb Pb:$0.98/lb Ag:$18.81/oz   440
120%   Cu:$3.49/lb Zn:$1.35/lb Pb:$1.07/lb Ag:$20.52/oz   577
         

 

    Operating Costs
(US$ million)
  NPV at 9%
(US$ million)
95.0%   1,711   370
97.5%   1,756   337
100.0%   1,801   304
107.5%   1,936   205
115.0%   2,072   107

 

    Capital Costs – Sustaining & Closure
(US$ million)
  NPV at 9%
(US$ million)
95.0%   201   308
97.5%   207   306
100.0%   212   304
107.5%   228   297
115.0%   244   291

 

Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
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Figure 19-1:        After-Tax NPV Sensitivity Graph

 

The after-tax NPV is most sensitive to metal prices, then to head grade, followed by operating costs, metallurgical recoveries, and capital costs.

 

Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
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20.0 Adjacent Properties

 

There are no adjacent properties to report in this section.

 

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21.0

Other Relevant Data and Information

 

No additional information or explanation is necessary to make this Technical Report Summary understandable and not misleading.

 

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22.0

Interpretation and Conclusions

 

SLR has the following conclusions by area.

 

22.1 Geology and Mineral Resources

 

As of December 31, 2020, exclusive of Mineral Reserves, Measured Mineral Resources are estimated to total 4.4 Mt at 2.00% Zn, 0.20% Pb, 0.67% Cu, and 19.61 g/t Ag and Indicated Mineral Resources are estimated to total 3.46 Mt at 1.37% Zn, 0.25% Pb, 0.45% Cu, and 24.96 g/t Ag. In addition, Inferred Mineral Resources are estimated to total 8.71 Mt at 1.28% Zn, 0.35% Pb, 0.33% Cu, and 31.23 g/t Ag.

Cerro Lindo is a Kuroko-style VMS deposit that comprises a number of lens-shaped massive and semi-massive sulphide bodies.

Three massive sulphide units, one semi-massive sulphide unit, and one mineralized volcanic rock unit have been recognized.

The control of mineralization is lithological, mineralogical, and structural. Most copper mineralization is located in a pyritic massive sulphide unit and most zinc mineralization is located in baritic massive sulphide units, with lesser disseminated mineralization as patches or stringers in the semi-massive sulphide and mineralized volcanic units.

The geological setting, geophysical studies, surface samples and geological mapping of the Cerro Lindo area present good exploration potential, as a number of targets have already been identified within a ten kilometre radius of the mining operation.

Protocols for drilling, sampling preparation and analysis, verification, and security meet industry standard practices and are appropriate for the purposes of a Mineral Resource estimate.

The QA/QC program as designed and implemented by Nexa is adequate, with no significant bias, to support the resource database. The resource database was verified by SLR and is suitable for Mineral Resource estimation.

The geological models are reasonably constructed using available geological information and are appropriate for Mineral Resource estimation.

The assumptions, parameters, and methodology used for the Cerro Lindo Mineral Resource estimate are appropriate for the style of mineralization and proposed mining methods.

 

22.2 Mining and Mineral Reserves

 

As of December 31. 2020, Proven and Probable Mineral Reserves are estimated to total 52.10 Mt at 1.44% Zn, 0.20% Pb, 0.61% Cu, and 21.17 g/t Ag.

Dilution and extraction factors follow the historical trend and are considered appropriate for the type of stoping methods employed at Cerro Lindo.

The level of dilution will likely increase in the latter years of production as the stopes on the fringes of the deposit will increase exposing the stopes to more external dilution.

The level of extraction will likely decrease under similar circumstances as more care will be required to avoid excess dilution in the ore.

Modifications to the mining approach for the areas requiring a more conventional method such as C&F will be required in the latter years when mining the fringes of the deposit. Paste backfill delivery is an issue when stopes are distant from the paste fill source requiring dilution with water which in turn can result in lower strength backfill. This does not represent a significant risk to the Mineral Reserve estimate, as C&F represents a small amount of the total Mineral Reserves. Pastefill can also be substituted with CRF. CRF can be mixed underground closer to the C&F stopes.

 

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22.3 Mineral Processing

 

The development of a geometallurgical model to predict metallurgical response during future processing at Cerro Lindo remains a work in progress. Additional work and metallurgical testing are necessary to confirm the validity of the relationships derived to date for throughput, grinding media consumption, recovery, and concentrate quality.

Analysis of historical production demonstrates that recoveries of copper, lead, and zinc are related to their head grades, while silver recoveries to the copper and lead concentrates tend to follow the copper and lead head grades.

Average LOM planned head grades of copper, lead, and silver for the next three years are similar to those experienced from 2016 to 2020 at 0.48%, 0.25%, and 0.70 oz/t, respectively, while the planned head grades of zinc decrease steadily from 1.8% after 2020.

Head grades towards the end of the LOM are anticipated to decrease, particularly those of zinc. Forecast recoveries and concentrate grades are initially in line with those of recent years, and then predicted to fall as head grades decrease.

Apart from decreasing head grades, no fundamental changes to the concentrator feed are anticipated, and in the SLR QP’s opinion, based on recent processing plant performance, the forecast recoveries and concentrate qualities for the near future are reasonable. With end of LOM zinc and lead head grades being well below the historical ranges, however, there is a risk that actual recoveries may be lower than forecast due to the lack of data on processing material with these low head grades.

A small amount of transition or supergene ore has been identified in two stopes, and test work is underway to determine economical alternatives for processing the ore, e.g., by campaigning the supergene material through the processing plant using conditions and reagents optimized specifically for this material.

 

22.4 Environment, Permitting and Social Considerations

 

No known environmental issues were identified during the site visit and documentation review. The Cerro Lindo Mine operation complies with applicable Peruvian permitting requirements and Nexa maintains a list of permits for the Project, which was provided to SLR. The approved permits address the authority’s requirements for operation of the underground mine, TSF, waste rock dumps, process plant, water usage, and effluents discharge. There is no discharge of industrial or domestic water to the environment at the mine site.

There is a comprehensive EMP in place, which includes a complete monitoring program for effluent discharges, gas emissions, air quality, non-ionizing radiation, noise, surface water quality, groundwater quality, soil quality, terrestrial biology (vegetation and wildlife), and aquatic biology. Cerro Lindo reports the results of the monitoring program to the authorities according to the frequency stated in the approved resolutions and no compliance issues have been raised by the authorities. In the SLR QP’s opinion the proposed environmental plans are adequate to address potential issues related to environmental compliance.

 

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Regarding the tailings dry-stack storage facilities, some movement of the tailings relative to the foundation has been noted from the tailings monitoring data, however, phreatic levels in the tailings are very low and the range of movement is considered to be within normal parameters. It is noted that the likelihood of the mine site experiencing a severe seismic event is relatively high given the mine site proximity to a major tectonic plate subduction zone.

Water management involves complete recirculation of water at the mine site where there is no fresh water withdrawal from natural water bodies and there is no discharge of industrial or treated sewage water to the environment. Fresh water is being supplied from a desalination plant located at the coast to meet site and process water make-up requirements. Water quality monitoring is carried out monthly at stations located along the Topará Creek at the mine site and in Jahuay beach at the discharge location from the desalination plant.

A Mine Closure Plan has been developed for all the Mine components within the context of Peruvian legislation and is periodically updated.

A social baseline description, assessment of socio-economic impacts, and a social management plan have been carried out to mitigate negative impacts and maximize positive benefits of the Cerro Lindo Mine. These components are generally consistent with social impact assessment practices. The Social Management Plan is comprised of three plans (Communications Plan, Community Relations Plan, and Community Development Plan) and includes measures and indicators to track social management performance. Nexa implements a complaint register to gather and respond to complaints from the public. In the SLR QP’s opinion the Social Management Plan and the grievance mechanism in place are adequate to address potential issues related to local communities.

Nexa hires from the local workforce when possible, both for skilled and unskilled workers. Outreach is conducted to the local community through social and employment programs.

The review of social aspects indicates that, at present, Nexa’s operations at the Cerro Lindo site in Peru are a positive contribution to sustainability and community well-being. Nexa has established and continues to implement its various Corporate policies, procedures, and practices in a manner consistent with relevant IFC Performance Standards. Nexa has, and continues to make, a positive contribution to the communities most affected by the Mine and has done a thorough job in collecting information to support its environmental effects assessment. Information regarding the outcomes of the complaints and grievances reports and site-specific health and safety practices was not provided at the time of this review, however, the corporate policies that guide these activities are clear and aligned with IFC Performance Standards.

The water quality concerns outside of the mine site that communities express from time to time remain a risk for the operations at Cerro Lindo.

 

22.5 Costs and Economic Analysis

 

SLR reviewed the sustaining capital costs and considers them to be appropriate for the remaining mine life. The sustaining capital costs are spread over the LOM period from 2021 to 2029, with mine closure in 2030. The bulk of the sustaining capital is mine development required to both access and develop the stoping blocks for mining. Equipment replacement is comprised of new equipment and equipment overhauls.

 

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The LOM operating cost forecast reflects the existing operating status of the mine. The SLR QP has reviewed recent operating costs and is of the opinion that the forecast is appropriate for the Cerro Lindo mine operation. Cerro Lindo staff also continue to assess operating efficiencies and approaches in efforts to improve operating costs in the different cost centres.

The economics of the Cerro Lindo mine operation are robust over the LOM, confirming that the Cerro Lindo Mineral Reserves are economically viable. The economic analysis shows an after-tax NPV, at an 9% base discount rate, of $304 million.

 

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23.0 Recommendations

 

SLR has the following recommendations by area.

 

23.1 Geology and Mineral Resources

 

1. Improve reconciliation processes by implementing a formal procedure and by forming a multi-disciplinary team to organize and analyze reconciliation results so that production data can be used to calibrate future resource and reserve models.

2. Investigate the potential 5% negative bias for lead at Inspectorate Lima.

3. Incorporate controls to reduce failure rates observed for some lead and silver CRMs.

4. Actively monitor blank results so any contamination issues can be corrected immediately, particularly the mine samples where there is no remaining core for re-analysis.

5. Take density measurements for SOP, SOB, and SLB domains, and collect more density samples at the extremities of the mineralization where resource and reserve shapes were generated.

6. Investigate building grade domains without separating them by geological domain to preserve grade continuity, evaluate incorporating mineralogy data, and review the geometry and trends of the grade domains

7. Improve DA angles particularly for the OB1 area based on grade trends and structural interpretations and potential further sub-domaining.

8. Continuously improve post-mineralization dike modelling to capture more of the logged intercepts and core angles, as well as contacts based on the underground mapping. Dikes are important to delimit internal waste and to guide the local interpolation strategy as some of them are behaving like faults by controlling the mineralization trends.

9. Build a more detailed structural model and structural domains to customize local search anisotropies and directions. It appears that there are at least four main structural trends present (northwest-southeast dipping northeast, northwest-southeast dipping southwest, northeast-southwest dipping northwest, and west-northwest/east-southeast dipping northwest and plunging west-northwest) that should be investigated further. Some mineralization domains appear to have mineralization trending in various directions due to local faulting and folding and further sub-domaining may be warranted.

10. Using the production data, monitor the chosen drill spacing for SSM and VM to determine if sufficient confidence is provided to support detailed mine planning, as these domains show less grade continuity and more grade variability than the massive sulphide domains.

11. Optimize resource shapes to reduce unnecessary internal dilution and improve grades, and possibly generate more shapes that were not built due to the resource shape construction methodology used.

12. Generate a no survey solid to account for the mined-out areas that were not surveyed, and document work to support the resultant solid.

13. Document all the data support to define non-recoverable solids and document any changes.

14. Complete the proposed 2021 exploration program, consisting of a 35,100 m of diamond drilling, and continue with advanced exploration, including geological mapping, and geochemical and geophysical surveys. The 2021 exploration program budget is approximately US$7.1 million.

 

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15. Complete the proposed 2021 mine geology drilling, consisting of 48,000 m with a goal of upgrading Inferred Mineral Resources to Indicated or Measured Resources (recategorization drilling) and for mine planning purpose (infill drilling) and ultimately convert them into Probable or Proven Mineral Reserves. The 2021 mine geology drilling program budget is approximately US$3.1 million.

 

23.2 Mining and Mineral Reserves

 

1. Review the stope designs to address the potential for increased dilution as mining nears the deposit limits. The use of shanty back design could be useful in addressing this issue.

2. Adjust the mining methods to reduce the level of internal dilution. Trade-off studies will be required to assess all aspects of the methods.

3. Complete a trade-off study comparing the use of CRF in areas that are distant from the paste fill source requiring high water content for delivery and lowering the backfill quality.

4. Consider upgrading the mine’s underground data-communications capabilities by replacing the present leaky-feeder system with a Wi-Fi fibre-optic network or a 4G-LTE cellular network.

5. An upgraded communications system will permit implementing centralized control and monitoring of underground operations from a control room on surface. These centralized functions can include real-time tracking of personnel and equipment, telemetry, ventilation-on-demand, and closed-circuit television, among other applications.

6. With a wireless communications system, consider implementing automated and/or tele-remote technology to operate equipment from control stations on surface. The technology can be used for mucking stopes, mucking development headings, production drilling, crushing, and operating rockbreakers, among other applications. A significant benefit is that it allows many mining operations to continue during otherwise non-productive periods, including lunch breaks, shift changes, blasting times, and ventilating smoke.

 

23.3 Mineral Processing

 

1. Re-evaluate the potential benefits that may be derived from a geometallurgical model to determine if additional test work and further development of a geometallurgical model will provide more valuable information than what is already available from test work results.

2. Conduct flotation test work on ore samples representing the lower lead and zinc head grades anticipated towards the end of the LOM to provide information on recovery and concentrate quality for planning purposes.

3. Continue investigations into development of processing conditions suitable for campaigning transition/supergene ore through the plant.

 

23.4 Environment, Permitting and Social Considerations

 

1. Continue identifying and comparing solutions for storing tailings for the remainder of the LOM.

2. Evaluate the long term environmental impacts of allowing the tailings valley runoff to pond against and seep through the Pahuaypite waste rock dump.

3. Continue with participatory monitoring of water quality and implement social commitments to help improve access to water and water quality in the area.

 

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4. Sourcing local employment may be difficult with expanded and continued operations as Nexa has already reported that sourcing local employees has, at times, been challenging. Continue with commitments in educating, training, recruitment, and diversity targeted to the local workforce.

5. Improve social and employment policies and procedures by developing mechanisms to communicate the outcomes of the employee and community focused activities with stakeholders and the public, particularly with a focus on access to water and perception about water quality.

6. Confirm the basis for the community of Chavin’s categorization as an Indigenous group by the Ministry of Culture in 2020 and conduct a gap analysis with respect to its 2018 impact assessment studies to determine the need for additional socio-cultural studies focused on Indigenous Peoples. The categorization of the community of Chavin by the Ministry of Culture should be explicitly acknowledged in Nexa’s Social Management Plan and its sub-plans (Communications Plan, Social Concertation Plan, and Community Development Plan) modified accordingly.

 

23.5 Costs and Economic Analysis

 

1. Continuously monitor costs and lock in costs as soon as possible to eliminate economic uncertainty.

2. Continue efforts towards improving efficiencies and approaches to mining and development operations as opportunities arise in these areas.

 

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24.0 References

 

AMEC, 2002: Cerro Lindo Project – Definitive Feasibility Study, Chincha – Perú. Project No. U632A.: report prepared by AMEC for Compañía Minera Milpo S.A.A., January 11, 2002.

 

AMEC, 2013: Auditoría de Recursos, Reservas y Planeamiento Unidad Cerro Lindo: report prepared by AMEC for Compañía Minera Milpo S.A.A., October 2013.

 

Amec Foster Wheeler Perú S.A., 2017: Cerro Lindo Polymetallic Mine, Chavin District, Chincha Province, Peru, NI 43-101 Technical Report on Operations, prepared for V.M. Holding S.A., by Bagnell, W., et al., with an effective date of June 30 2017 (September 19, 2017).

 

Amphos 21, 2016: Diagnóstico del Cumplimiento de ECAs en la Quebrada Topará - Estudio Hidroquímico y de Calidad de Aguas - Unidad Minera Cerro Lindo, report prepared for Compañía Minera Milpo S.A.A. (June 2016).

 

Ausenco, 2017: Cross Check Depósito de Relaves Pahuaypite 1 y Pahuaypite 2 prepared for Votorantim Metais Holding (January 2017).

 

Canadian Dam Association (CDA) Dam Safety Guidelines 2007 (Revised 2013).

 

Canadian Institute of Mining, Metallurgy and Petroleum (CIM), 2014: CIM Definition Standards for Mineral Resources and Mineral Reserves, adopted by the CIM Council on May 10, 2014.

 

Canales, J., 2016: Cartografiado Geologico y Muestreo Geoquimico y Litogeoquimico Cerro Lindo: internal report prepared by Compañía Minera Milpo S.A.A., 1 January 2016.

 

Cesel Ingenieros, 2016, INGENIERÍA CONCEPTUAL PARA LA ESTABILIZACIÓN DE LA PLANTA CONCENTRADORA A 21K U.M. CERRO LINDO, prepared for Milpo, December 16, 2016.

 

Cesel Ingenieros, 2017, Ingeniería Conceptual Para La Estabilización Y Automatizacion De La Planta Concentradora A 21k U.M. Cerro Lindo, prepared for Milpo, February 15, 2017.

 

Franklin, J.M., Sangster, D.M., and Lydon, J.W., 1981: Volcanic-Associated Massive Sulfide Deposits: in, Skinner, B.J. (ed.), Economic Geology Seventy-fifth Anniversary Volume: Economic Geology Publishing Company, pp. 485–627.

 

Gariépy, L. and Hinostroza, J., 2004: El Yacimiento Tipo Sulfuro Masivo Volcanogénico Cerro Lindo, Departamento de Ica, Perú: internal report prepared by Compañía Minera Milpo S.A.A.

 

GEMIN, 2005: Revised Feasibility Study: report prepared by GEMIN for Compañía Minera Milpo S.A.A.

 

Geoconsultoria, 2018: Evaluación Anual de Seguridad 2018 - Depósito de Relave Filtrado y Presa Pahuaypite 1, report prepared for Unidad Minera Cerro Lindo Nexa Resources (March 2019).

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Geoconsultoria, 2018: Evaluación Anual de Seguridad 2018 - Depósito de Relave Filtrado y Presa Pahuaypite 2, report prepared for Unidad Minera Cerro Lindo Nexa Resources (March 2019).

 

GEOMEC, Geomecánica Latina S.A., i-Test Laboratorio, “Raporte de Ensayo de Laboratorio-190128/LMR/i-TEST, Raporte Final, Lima, 16 de diciembre del 2019.

 

Geoservice Ingenieria, 2016: Modificación del Plan de Cierre de Minas de la Unidad Minera Cerro Lindo, report prepared for Compañía Minera Milpo S.A.A. (March 2016).

 

Geotech, 2020: Report on a Helicopter-Borne Versatile Time Domain Electromagnetic (VTEM) Survey, Project GL190048, February 2020, 68 p.

 

Golder Associates, 2019: Estudio de Áreas Contaminadas Unidad Minera Cerro Lindo – Caracterización Geoquímica en el Marco de Ejecución de Investigación Ambiental Confirmatoria (Study of Cerro Lindo Contaminated Areas – Geochemical Characterization Framework for Environmental Monitoring), technical memorandum prepared for Nexa Resources S.A. (May 17, 2019).

 

Hinostroza, J., 2016: Geología de la Mina Cerro Lindo: internal report prepared by Compañía Minera Milpo S.A.A., May 13, 2016.

 

Imaña, M., 2015: Revisión De Trabajos De Exploración En Zona Norte Mina Cerro Lindo (Estratigrafía Química, Alteración Y Potencial De Exploración) Chincha – Perú: report prepared by Lithogeochemistry & Mineral Exploration Consulting for Compañía Minera Milpo S.A.A., June 27, 2015.

 

Ishihara, S. 1974: Geology of the Kuroko Deposits: Society of Mining Geologists of Japan, Special Issue 6, 473 p.

 

Lavado, M., 2015: Informe Geológico - Mina Cerro Lindo: report prepared for Compañía Minera Milpo S.A.A., October 2015.

 

Meffre, S., and Thompson, J., 2016: U-Pb Geochronology of Rocks for Milpo, August 2016. Codes Technology Services. ARC Centre of Excellence in Ore Deposits. University of Tasmania.

 

Milpo, 2016e: Exploraciones Brownfield Resultados 2015 Programa 2016. PE_CL_Resultados 2015-Programa 2016_15may16.pptx: PowerPoint presentation prepared by the UM Cerro Lindo, May 2016.

 

Milpo, 2016f: Memoria Anual 2016.

 

Mira Geoscience Ltd., 2020: Professional Services Memorandum for IP and MT data, dated August 31, 2020, 21 p.

 

Nexa Resources S.A., 2019: Corporate Policies.

 

Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
Technical Report Summary - January 29, 2021
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Nexa Resources S.A., 2020a: An internal legal opinion by Magaly Bardales, Legal Corporate Manager and Institutional Affairs, Nexa, a letter to RPA expressing an opinion on the Section 4 content of the Technical Report (August 16, 2020).

 

Nexa Resources S.A., 2020b: Reunion de Resultados, Directorio de Exploracion de Mineral y tecnologia – presentation file, February 2020.

 

Nexa Resources S.A., 2020c: Informe de Aseguramiento y control de calidad QAQC (Del 01 Mayo 2019 al 29 Febrero 2020).

 

Nexa Resources S.A., 2020d: Reporte de Recursos Minerales U.M. Cerro Lindo, Ica, Peru, July 2020.

 

Nexa Resources S.A., 2020e: Market Intelligence team, Industry Scenario 2020 – Supply and Costs presentation, (July 2020).

 

Nexa Resources S.A., 2020f: 2019 Annual Performance Report, March 31, 2020.

 

Ohmoto, H., and Skinner, B.J. (eds.), 1983: The Kuroko and Related Volcanogenic Massive Sulfide Deposits: Economic Geology, Monograph 5, 604 p.

 

Roscoe Postle Associates Inc. (RPA), 2019: Technical Report on the Cerro Lindo Mine, Department of Ica, Peru, a NI 43-101 Technical Report dated December 3, 2019, filed on SEDAR December 17, 2019.

 

Singer, D.A., 1986: Descriptive Model of Kuroko Massive Sulfide, Model 28a: in Cox, D.P. and Singer, D.A. (eds.), Mineral Deposit Models, U.S. Geological Survey Bulletin 1693.

 

SRK Consulting, 2016: Modelamiento Geomecánico 3D y Evaluación de las Condiciones de Estabilidad Global de la Mina Cerro Lindo, 16-M-048-14. Draft (October 2016).

 

SRK Consulting, 2017: Modelamiento Geomecánico 3D y Evaluación de las Condiciones de Estabilidad Global de la Mina Cerro Lindo, 16-M-048-14. Final (March 2017).

 

SRK Consulting, 2018: Modificación del Estudio de Impacto Ambiental de la Unidad Minera Cerro Lindo para Ampliación de la Planta Concentradora a 22.5K TMD e Instalaciones Adicionales, reports prepared for Compañía Minera Milpo S.A.A. (January/February 2018).

 

SVS Ingenieros S.A.C., 2010: Estudio de Ingeniería Básica y de Detalle Depósito de Relaves Filtrados Pahuaypite 2. Project No. 1-M-048-028. Drawing 10-01 dated December 2010.

 

Transmin Metallurgical Consultants, 2020, Estudio Geometalurgico Fase 3 para Unidad Minera Cerro Lindo, prepared for Nexa Resources Peru S.A. (May 14, 2020).

 

Urabe, T., Scott, S.D., Hattori, K., 1983: A Comparison of Foot-Wall Alteration And Geothermal Systems Beneath Some Japanese And Canadian Volcanogenic Massive Sulfides Deposits: in: Ohmoto, H. and Skinner, B.J. (eds.), The Kuroko and Related Volcanogenic Massive Sulfide Deposits. Economic Geology, Monograph 5.

 

Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
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US Securities and Exchange Commission, 2018: Modernized Property Disclosure Requirements for Mining Registrants as described in Subpart 229.1300 of Regulation S-K, Disclosure by Registrants Engaged in Mining Operations and Item 601 (b)(96) Technical Report Summary.

 

Zalazar, H., and Landa, C., 1993: Geología de los Cuadrángulos de Mala, Lunahuana, Tupe, Conoyca, Chincha, Tanatara y Castrovirreyna: Ingemmet, Sector Energia y Minas. Peru. Boletín No. 44.

 

Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
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25.0 Reliance on Information Provided by the Registrant

 

This Technical Report Summary has been prepared by SLR for Nexa. The information, conclusions, opinions, and estimates contained herein are based on:

 

Information available to SLR at the time of preparation of this report,

 

Assumptions, conditions, and qualifications as set forth in this report, and

 

Data, reports, and other information supplied by Nexa.

 

For the purpose of the Summary and Section 3 of this report, SLR has relied on ownership information provided in an internal legal opinion by Magaly Bardales, Legal Corporate Manager and Institutional Affairs dated August 16, 2020 (Nexa, 2020a) and a supporting email from Nexa dated January 18, 2021. SLR has not researched property title or mineral rights for the Cerro Lindo Mine as we consider it reasonable to rely on Nexa’s legal counsel who is responsible for maintaining this information.

 

SLR has relied on Nexa for guidance on applicable taxes, royalties, and other government levies or interests, applicable to revenue or income from the Mine in the Summary and Section 19. As the Mine has been in operation for over ten years, Nexa has considerable experience in this area.

 

The Qualified Persons have taken all appropriate steps, in their professional opinion, to ensure that the above information from Nexa is sound.

 

Except for the purposes legislated under U.S. federal securities laws and the Canadian provincial securities laws, any use of this Technical Report Summary by any third party is at that party’s sole risk.

 

Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
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26.0

Date and Signature Page

 

This report titled “Technical Report Summary on the Cerro Lindo Mine, Department of Ica, Peru” with an effective date of December 31, 2020 was prepared and signed by:

 

SLR Consulting (Canada) Ltd. (Signed) SLR Consulting (Canada) Ltd.

 

Dated at Toronto, ON
January 29, 2021

 

Nexa Resources S.A. | Cerro Lindo Mine, SLR Project No: 233.03246.R0000
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Exhibit 15.2

 

 

 

Technical Report Summary on the El Porvenir Mine, Department of Pasco, Peru

 

SLR Project No: 233.03259.R0000

 

Prepared by

SLR Consulting (Canada) Ltd.

55 University Ave., Suite 501

Toronto, ON M5J 2H7

for

 

Nexa Resources S.A.

Rúa Guaicuí, 20 – 14° Andar

Belo Horizonte/MG

30380-380

 

Effective Date – December 31, 2020

Signature Date - January 15, 2021

 

FINAL

 

Distribution: 1 copy – Nexa Resources S.A.
  1 copy – SLR Consulting (Canada) Ltd.

 
   

 

 

Contents

 

1.0 Executive Summary 1-1
     
1.1 Summary 1-1
1.2 Economic Analysis 1-7
1.3 Technical Summary 1-11
     
2.0 Introduction 2-1
     
2.1 Site Visits 2-1
2.2 Sources of Information 2-1
2.3 List of Abbreviations 2-2
     
3.0 Property Description 3-1
     
3.1 Location 3-1
3.2 Land Tenure 3-1
3.3 Royalties 3-8
3.4 Surface Rights and Easements 3-9
3.5 Material Government Consents 3-12
     
4.0 Accessibility, Climate, Local Resources, Infrastructure and Physiography 4-1
     
4.1 Accessibility 4-1
4.2 Climate 4-1
4.3 Local Resources 4-1
4.4 Infrastructure 4-1
4.5 Physiography 4-2
     
5.0 History 5-1
     
5.1 Ownership, Exploration and Development History 5-1
5.2 Past Production 5-2
     
6.0 Geological Setting, Mineralization, and Deposit 6-1
     
6.1 Regional Geology 6-1
6.2 Local Geology 6-5
6.3 Property Geology 6-12
6.4 Alteration 6-15
6.5 Mineralization 6-15
6.6 Deposit Types 6-16
6.7 Skarn 6-16
6.8 Hydrothermal Vein and Breccia 6-17
6.9 Stratabound 6-18

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

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7.0 Exploration 7-1
     
7.1 Exploration 7-1
7.2 Integration of El Porvenir and Atacocha 7-1
7.3 2019 El Porvenir Exploration 7-3
7.4 2020 Exploration Program 7-3
7.5 2021 Exploration Program 7-11
7.6 Drilling 7-11
7.7 Hydrogeology Data 7-22
7.8 Geotechnical Data 7-22
     
8.0 Sample Preparation, Analyses, and Security 8-1
     
8.1 Density Determinations 8-1
8.2 Sample Preparation and Analysis 8-3
8.3 Quality Assurance and Quality Control 8-6
8.4 QA/QC Recommendations 8-30
8.5 Data Management 8-30
8.6 Sample Security 8-30
     
9.0 Data Verification 9-1
     
9.1 Databases and Internal Verification 9-1
9.2 Previous Verification 9-1
9.3 SLR Verification 9-2
     
10.0 Mineral Processing and Metallurgical Testing 10-1
     
10.1 Test Work 10-1
10.2 Operational Performance 10-5
10.3 Deleterious Elements 10-7
     
11.0 Mineral Resource Estimates 11-1
     
11.1 Summary 11-1
11.2 Resource Database 11-2
11.3 Geological Interpretation 11-5
11.4 Geological Modelling 11-8
11.5 Domain Modelling 11-14
11.6 Resource Assays 11-23
11.7 Treatment of High Grade Assays 11-24
11.8 Compositing 11-43
11.9 Trend Analysis 11-58
11.10 Search Strategy and Grade Interpolation Parameters 11-64
11.11 Bulk Density 11-67
11.12 Block Models 11-71
11.13 Net Smelter Return and Cut-Off Value 11-71
11.14 Classification 11-75

 

 

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11.15 Block Model Validation 11-82
11.16 Mineral Resource Reporting 11-90
11.17 Comparison to Previous Mineral Resource Estimates 11-94
     
12.0 Mineral Reserve Estimates 12-1
     
12.1 Summary 12-1
12.2 Dilution 12-2
12.3 Net Smelter Return 12-4
12.4 Cut-Off Grade 12-7
     
13.0 Mining Methods 13-1
     
13.1 Introduction 13-1
13.2 Mine Design and Mining Methods 13-3
13.3 Geomechanics and Ground Support 13-17
13.4 Hydrogeology 13-23
13.5 Infrastructure and Mine Services 13-23
13.6 Mine Equipment 13-47
13.7 Personnel 13-48
13.8 Life of Mine Plan 13-49
     
14.0 Processing and Recovery Methods 14-1
     
14.1 Process Description 14-1
14.2 Energy, Water, and Process Materials Requirements 14-2
14.3 Manpower 14-2
     
15.0 Infrastructure 15-1
     
15.1 Power Plant and Distribution 15-1
15.2 On-Site Roads 15-1
15.3 Utilities and Services 15-1
15.4 Sewage Collection and Disposal 15-2
15.5 Site Security 15-2
15.6 Communication and IT Systems 15-2
15.7 Vehicle Fueling Facility and Mine Equipment Ready Line 15-2
15.8 Site Buildings and Facilities 15-2
15.9 Tailings Storage 15-5
15.10 Waste Rock Storage Facilities 15-10
     
16.0 Market Studies 16-1
     
16.1 Markets 16-1
16.2 Contracts 16-4
     

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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17.0 Environmental Studies, Permitting, and Plans, Negotiations, or Agreements with Local Individuals or Groups 17-1
     
17.1 Environmental Aspects 17-1
17.2 Mine Waste and Water Management 17-8
17.3 Project Permitting 17-12
17.4 Social or Community Requirements 17-17
17.5 Mine Closure Requirements 17-23
     
18.0 Capital and Operating Costs 18-1
     
18.1 Capital Costs 18-1
18.2 Operating Costs 18-2
     
19.0 Economic Analysis 19-1
     
19.1 Economic Criteria 19-1
19.2 Cash Flow 19-3
19.3 Sensitivity Analysis 19-8
     
20.0 Adjacent Properties 20-1
     
21.0 Other Relevant Data and Information 21-1
     
22.0 Interpretation and Conclusions 22-1
     
22.1 Geology and Mineral Resources 22-1
22.2 Mining and Mineral Reserves 22-1
22.3 Mineral Processing 22-1
22.4 Environmental, Permitting and Social Considerations 22-2
22.5 Costs and Economic Analysis 22-3
     
23.0 Recommendations 23-1
     
23.1 Geology and Mineral Resources 23-1
23.2 Mining and Mineral Reserves 23-2
23.3 Mineral Processing 23-2
23.4 Environmental, Permitting and Social Considerations 23-2
23.5 Costs and Economic Analysis 23-3
     
24.0 References 24-1
     
25.0 Reliance on Information Provided by the Registrant 25-1
     
26.0 Date and Signature Page 26-1

 

 

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TABLEs

 

Table 1-1: ROM Production – Years 2015 to 2020 1-1
Table 1-2: After-Tax Cash Flow Summary 1-10
Table 1-3: Summary of Mineral Resources – December 31, 2020 1-13
Table 1-4: Mineral Reserves –December 31, 2020 1-15
Table 1-5: Mine Production Schedule 1-16
Table 1-6: Life of Mine Capital Budget 1-19
Table 1-7: Operating Budget 1-20
Table 3-1: El Porvenir Mining Concessions 3-2
Table 3-2: Payments Made for Concessions in 2020 3-7
Table 3-3: Concessions Subject to Royalties Payable to Nexa Atacocha 3-9
Table 3-4: Royalty Payments to Nexa Atacocha 3-9
Table 3-5: Main Government Consents 3-12
Table 5-1: History of the El Porvenir Mine 5-1
Table 5-2: Mine Production History 5-2
Table 5-3: Concentrate Production – 2016 to 2020 5-4
Table 7-1: Drilling Summary at Porvenir 7-12
Table 7-2: Summary of Drilling Excluded from Mineral Resource Estimate 7-12
Table 7-3: Summary of Drilling Included in Mineral Resource Estimate 7-13
Table 7-4: Channel Sampling Summary at Porvenir 7-13
Table 7-5: Core Recovery by Domain – 2017 to 2020 7-19
Table 8-1: Number of Density Measurements by Sample Type and Year 8-1
Table 8-2: Laboratory Detection Limits 8-3
Table 8-3: Control Sample Insertion Rate and Failure Criteria 8-7
Table 8-4: QC Insertion Rates 8-7
Table 8-5: CRMs Used at Porvenir Since 2014 8-9
Table 8-6: 2014 to 2017 CRMs Performance 8-10
Table 8-7: 2017 to 2020 CRM Performance 8-13
Table 8-8: 2017 to 2020 Fine Blank Results 8-19
Table 8-9: 2017 to 2020 Coarse Blank Results 8-19
Table 8-10: Duplicate Types and Descriptions 8-21
Table 8-11: 2017 to 2020 Porvenir Duplicate Performance 8-23

 

 

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Table 8-12: 2017 to 2020 Porvenir External Check Performance 8-27
Table 9-1: SLR Assay Certificate Verification Results 9-2
Table 10-1: Concentrator Operational Performance 10-6
Table 11-1: El Porvenir Mineral Resources - December 31, 2020 11-2
Table 11-2: Individual Mineralization Domains 11-10
Table 11-3: Mineralization Group Zone Domains 11-11
Table 11-4: Zn, Cu, Ag, and Pb Grade Domains 11-14
Table 11-5: Zinc Estimation Domains 11-17
Table 11-6: Lead-Silver Estimation Domains 11-18
Table 11-7: Copper Estimation Domains 11-19
Table 11-8: Capping Levels by Mineralization Domains 11-25
Table 11-9: Estimation Domain Capped and Raw Assay Statistics for Zinc (Zn%) 11-28
Table 11-10: Estimation Domain Capped and Raw Assay Statistics for Lead (Pb%) 11-32
Table 11-11: Estimation Domain Capped and Raw Assay Statistics for Silver (Ag g/t) 11-35
Table 11-12: Estimation Domain Capped and Raw Assay Statistics for Copper (Cu%) 11-39
Table 11-13: Estimation Domain Composite Statistics for Zinc (Zn%) 11-44
Table 11-14: Estimation Domain Composite Statistics for Lead (Pb%) 11-48
Table 11-15: Estimation Domain Composite Statistics for Silver (Ag g/t) 11-52
Table 11-16: Estimation Domain Composite Statistics for Copper (Cu%) 11-55
Table 11-17: Zinc Variogram Parameters 11-60
Table 11-18: Zinc Estimation Parameters 11-65
Table 11-19: Silver Estimation Parameters 11-66
Table 11-20: Density Data Statistics 11-68
Table 11-21: Block Model Setup 11-71
Table 11-22: NSR Data 11-71
Table 11-23: Cut-Off Grade Calculation by Mining Zone and Method 11-74
Table 11-24: Nexa Search Ellipse Ranges for Classification Criteria 11-77
Table 11-25: Comparison of ID3, OK, and NN Zinc Grades – Measured and Indicated Blocks 11-82
Table 11-26: EL Porvenir Underground Comparison of 2020 versus 2019 Mineral Resources 11-95
Table 12-1: El Porvenir Mining Zones 12-1
Table 12-2: Mineral Reserves – December 31, 2020 12-2
Table 12-3: NSR Data 12-4

 

 

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Table 12-4: Cut-Off Grade Calculation by Mining Zone and Method 12-8
Table 13-1: Mining Methods in Active Mining Zones 13-1
Table 13-2: Long Term Stope Design Parameters 13-3
Table 13-3: Development Design Parameters 13-3
Table 13-4: Long Term Production Rate Parameters 13-4
Table 13-5: Long Term Parameters For Dilution And Recovery 13-4
Table 13-6: Mine Production -- Years 2018 to 2020 13-5
Table 13-7: Development Advance - Years 2017 to 2020 13-5
Table 13-8: Cut and Fill Mining Method at El Porvenir 13-6
Table 13-9: Advantages and Disadvantages of Avoca Compared with Cut and Fill 13-12
Table 13-10: Sublevel Stoping Method at El Porvenir 13-15
Table 13-11: Rock Mass Characteristics 13-18
Table 13-12: Magnitude and Azimuth of the In-Situ Stresses 13-18
Table 13-13: Seismic Events 13-19
Table 13-14: Ground Support Procedures 13-22
Table 13-15: Mine Infrastructure 13-23
Table 13-16: Ventilation Balance - Intake Airflow 13-26
Table 13-17: Ventilation Balance - Return Airflow 13-26
Table 13-18: Ventilation Requirement 13-27
Table 13-19: Main Ventilation Fans 13-27
Table 13-20: Main Ventilation Branches 13-28
Table 13-21: Dewatering System 13-32
Table 13-22: Water Tanks 13-34
Table 13-23: Hydraulic Backfill Preparation and Distribution 13-35
Table 13-24: Design Criteria of Hydraulic Backfill 13-36
Table 13-25: Exits to Surface 13-37
Table 13-26: Supply of Electric Power 13-39
Table 13-27: Picasso Shaft 13-46
Table 13-28: Trackless Mobile Equipment 13-47
Table 13-29: Track Equipment 13-48
Table 13-30: Required Mechanical Availability for Strategic Equipment 13-48
Table 13-31: Nexa Personnel - Underground Mine 13-49
Table 13-32: Mine Production Schedule 13-49

 

 

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Table 13-33: Mine Production by Mining Method 13-50
Table 13-34: Production by Mining Zone 13-50
Table 13-35: Development Schedule 13-51
Table 16-1: Third Party Contractors 16-4
Table 16-2: Quality of El Porvenir Zinc Concentrate 16-6
Table 16-3: Contaminant Element Penalties - Lead Concentrate 16-6
Table 16-4: Contaminant Element Penalties - Copper Concentrate 16-6
Table 17-1: Summary of Key Environmental Effects and Management Strategies 17-6
Table 17-2: Water Quality Monitoring Locations 17-11
Table 17-3: Environmental, Mine Closure, and Tailings Disposal Licences 17-13
Table 17-4: Summary of Main Closure Activities 17-25
Table 18-1: Life of Mine Capital Budget 18-1
Table 18-2: Operating Budget 18-2
Table 18-3: Nexa Personnel at El Porvenir Mine – December 31, 2020 18-3
Table 19-1: After-Tax Cash Flow Summary 19-4
Table 19-2: Cash Flow Analysis 19-8
Table 19-3: After-Tax Sensitivity Analysis 19-9
Table 20-1: Production - Atacocha Mine 20-1

 

FIGURES

 

Figure 3-1: Mine Location 3-4
Figure 3-2: Land Tenure 3-5
Figure 3-3: Surface Rights 3-11
Figure 4-1: Typical Landscape at El Porvenir 4-2
Figure 6-1: Simplified Geological Map of Peru 6-3
Figure 6-2: Morphostructural Map of Peru 6-4
Figure 6-3: Local Geology 6-7
Figure 6-4: Generalized Stratigraphic Column 6-8
Figure 6-5: Regional Geological Setting with Major Structural Features 6-11
Figure 6-6: Representative Cross Sections through El Porvenir Area 6-14
Figure 6-7: Schematic Diagram of Skarn, Replacement and Hydrothermal Vein Mineralization 6-18
Figure 6-8: Schematic Diagram of Stratabound Deposit at El Porvenir 6-19

 

 

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Figure 7-1: El Porvenir and Atacocha Mines with Underground Workings 7-2
Figure 7-2: Sara Project Location Map and Example Section 7-4
Figure 7-3: Remote Sensing and Alteration Anomalies 7-6
Figure 7-4: Geology, Flight Plan, and 3D Geophysical Model 7-7
Figure 7-5: Geophysical Anomalies at Level 2700 7-8
Figure 7-6: Brownfield Targets of the Cerro Pasco Complex 7-10
Figure 7-7: Plan View of Drill Holes 7-15
Figure 7-8: Cross Section Showing Drill Holes and Geological Interpretation 7-16
Figure 7-9: Plan View of Channel Sampling 7-17
Figure 8-1: Distribution of Density Samples Used for 2020 Mineral Resource Estimate by Year Analyzed 8-2
Figure 8-2: Schematic Flow Chart for Sample and Data Controls 8-6
Figure 8-3: CRMs PEPSSTD001 and PEPSSTD002 Results for Zinc –Inspectorate EP (2018 to 2019) 8-16
Figure 8-4: CRMs PEPSSTD002 and PEPSSTD003 Results for Lead –Inspectorate EP (2018 to 2019) 8-17
Figure 8-5: 2017 to 2020 Porvenir Blank Zn and Pb Assays – Inspectorate EP Laboratory 8-20
Figure 8-6: 2017 to 2020 Porvenir Field Duplicates for Zn and Pb Assays – Inspectorate EP Laboratory 8-24
Figure 8-7: 2017 to 2020 Porvenir Coarse Reject Duplicates for Zn and Pb Assays – Inspectorate EP Laboratory 8-25
Figure 8-8: 2017 to 2020 Porvenir Pulp Duplicates for Zn and Pb Assays – Inspectorate EP Laboratory 8-26
Figure 8-9: 2017 to 2020 Porvenir External Checks for Zn and Pb Assays – Inspectorate EP Laboratory 8-29
Figure 9-1: Assay Sampling Coverage (Zn) 9-4
Figure 9-2: Density Sampling Coverage 9-6
Figure 10-1: Bulk Mineralogical Analysis 10-2
Figure 10-2: Sulphide Mineral Breakdown 10-3
Figure 10-3: Historical Recovery to Concentrate 10-7
Figure 11-1: 3D View of El Porvenir Mineralized Solids and Drill holes 11-4
Figure 11-2: El Porvenir Lithological and Control Type Domains 11-6
Figure 11-3: El Porvenir Structure and Emplacement Type Domains 11-7
Figure 11-4: OB_Vcn3 showing drill holes and updated mapping 11-9
Figure 11-5: El Porvenir Mineralization Group Zone Domains – Plan view 11-12
Figure 11-6: El Porvenir Mineralization Group Zone Domains – Cross Section 11-13

 

 

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Figure 11-7: Plan and Cross Section Copper Grade Domains for VCN3 11-15
Figure 11-8: Zinc Domains 11-20
Figure 11-9: Lead-Silver Domains 11-21
Figure 11-10: Copper Domains 11-22
Figure 11-11: Zn Capping Analysis for 1300 (VCN3EI1) Domain 11-24
Figure 11-12: Composite Length Comparison 11-44
Figure 11-13: Zinc Normal Score Experimental and Modelled Variograms for Domain Progreso 307 11-59
Figure 11-14: 3D View of Density Domains 11-69
Figure 11-15: 3D View of Density Values 11-70
Figure 11-16: Zinc Recovery Curve 11-73
Figure 11-17: Lead Recovery Curve 11-73
Figure 11-18: Copper Recovery Curve 11-74
Figure 11-19: Histogram of Distance (M) by Category and Continuity Zone 11-79
Figure 11-20: Final Classification Designation – Plan View 11-80
Figure 11-21: Final Classification Designation – Longitudinal Section 11-81
Figure 11-22: Vertical Section Showing Zn Blocks Versus Composite Grades 11-85
Figure 11-23: Vertical Section Showing Pb Blocks Versus Composite Grades 11-86
Figure 11-24: Vertical Section Showing Ag Blocks Versus Composite Grades 11-87
Figure 11-25: Vertical Section Showing Cu Blocks Versus Composite Grades 11-88
Figure 11-26: Swath Plot: Zn Grade Variation Along X, Y, and Z 11-89
Figure 11-27: Zn OK, ID3, Nn Blocks Versus Zn Composite Histograms 11-90
Figure 11-28: Plan View of Mineral Resources Inclusive and Exclusive of Mineral Reserves 11-92
Figure 11-29: Longitudinal Section of Mineral Resources Inclusive and Exclusive of Mineral Reserves 11-93
Figure 12-1: Schematic Section View of Stope Illustrating Dilution and Extraction Values in a Stope 12-3
Figure 12-2: Zinc Recovery Curve 12-6
Figure 12-3: Lead Recovery Curve 12-6
Figure 12-4: Copper Recovery Curve 12-7
Figure 13-1: Active Mining Zones 13-2
Figure 13-2: Cut and Fill Stoping – Longitudinal View 13-7
Figure 13-3: Sublevel Stoping – Longitudinal View 13-8
Figure 13-4: Cut and Fill Mining Cycle 13-9

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Figure 13-5: Access to Cut and Fill Stopes 13-11
Figure 13-6: Avoca Mining Method 13-13
Figure 13-7: Sublevel Stoping Mining Cycle 13-14
Figure 13-8: Typical Layout for Longhole Drilling 13-17
Figure 13-9: Procedures for Seismic Events 13-21
Figure 13-10: Ventilation System 13-25
Figure 13-11: Main Ventilation Fan 13-28
Figure 13-12: Ventilation Ducting Used to Ventilate Work Headings 13-29
Figure 13-13: Mine Dewatering System 13-30
Figure 13-14: Dewatering Sequence 13-31
Figure 13-15: Drainage from Backfilling Stopes 13-33
Figure 13-16: Hydraulic Backfill System 13-35
Figure 13-17: Hydraulic Backfill Plant 13-37
Figure 13-18: Emergency Egress Routes and Refuge Stations 13-38
Figure 13-19: One-Line Diagram of the El Porvenir Electrical System 13-41
Figure 13-20: Standard Layout for an Underground Electrical Substation – Plan View 13-43
Figure 13-21: Electrical Equipment in a Typical Substation 13-44
Figure 14-1: Process Flow Sheet 14-3
Figure 15-1: Site Layout 15-4
Figure 15-2: Tailings Storage Facility Layout with Dam at Elevation 4,064 MASL 15-6
Figure 15-3: Tailings Storage Facility Main Dam Layout at Elevation 4,064 MASL 15-7
Figure 15-4: Tailings Storage Facility Main Dam Section to Elevation 4,100 MASL 15-9
Figure 16-1: Zinc Price Outlook (2020-2025) 16-2
Figure 16-2: Refined Copper Market Balance (2020-2025) 16-3
Figure 16-3: Copper Price Outlook (2020-2025) 16-4
Figure 19-1: After-Tax NPV Sensitivity Graph 19-10
Figure 20-1: Mining Concessions in the Vicinity of El Porvenir 20-3

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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1.0 Executive Summary

 

1.1 Summary

 

SLR Consulting Ltd. (SLR) was retained by Nexa Resources S.A. (Nexa) to prepare an independent Technical Report Summary on the El Porvenir Mine (the Mine or El Porvenir), located in Pasco Province, central Peru. The purpose of this Technical Report Summary is to support the public disclosure of updated Mineral Reserve and Mineral Resource estimates. This Technical Report Summary conforms to United States Securities and Exchange Commission’s (SEC) Modernized Property Disclosure Requirements for Mining Registrants as described in Subpart 229.1300 of Regulation S-K, Disclosure by Registrants Engaged in Mining Operations (S-K 1300) and Item 601 (b)(96) Technical Report Summary. SLR personnel visited the site from September 5 to 7, 2018.

 

Nexa is a publicly traded company on the Toronto Stock Exchange (TSX) and the New York Stock Exchange (NYSE). Nexa is a reporting issuer in all provinces and territories of Canada and is under the jurisdiction of the Ontario Securities Commission.

 

Nexa is a large-scale, low-cost, integrated zinc producer with over 60 years of experience developing and operating mining and smelting assets in Latin America. Nexa has a diversified portfolio of polymetallic mines (zinc, lead, copper, silver, and gold) and also greenfield projects at various stages of development in Brazil and Peru. In Brazil, Nexa owns and operates two underground mines, Vazante and Morro Agudo (Zn and Pb). Nexa also operates two zinc smelters in Brazil (Três Marias and Juiz de Fora). In Peru, Nexa operates the El Porvenir (Zn, Pb, Cu, and Ag), Cerro Lindo (Zn, Cu, Pb, and Ag), and Atacocha (Zn, Cu, Pb, Au, and Ag) mines, as well as the Cajamarquilla zinc smelter near Lima. Nexa’s development projects in Peru include Magistral, Shalipayco, Florida Canyon (JV with Solitario), Hilarión, and Pukaqaqa. In Brazil, Nexa is developing the Aripuanã Zinc Project (Zn, Pb, Cu, Au, and Ag), which is currently under construction and is owned by Mineração Dardanelos Ltda. (Dardanelos), a wholly-owned subsidiary of Nexa.

 

El Porvenir is an underground, polymetallic mine located in Peru’s Central Andes mountain region at an elevation of approximately 4,200 metres above sea level (MASL). El Porvenir is situated 315 km by road northeast of Lima, the capital city, and 13 km from the city of Cerro de Pasco. The Mine began operations in 1949, and recent production has been at a rate of approximately 6,000 tonnes per day (tpd). Table 1-1 presents El Porvenir's run of mine (ROM) production for the years 2015 to 2020. The processing plant has a capacity for treating ore at a rate of approximately 2.28 million tonnes per annum (Mtpa).

 

Table 1-1: ROM Production – Years 2015 to 2020

Nexa Resources S.A. – El Porvenir Mine

 

Item   Unit   2015   2016   2017   2018   2019   2020
Tonnes   t   2,108,821   2,154,151   1,834,511   2,149,927   2,120,765   1,502,618
Zn   %   3.21   3.22   2.86   3.04   2.92   2.65
Pb   %   0.93   0.99   1.04   0.98   1.01   0.93
Cu   %   0.17   0.14   0.13   0.15   0.15   0.17
Ag   g/t   54.38   60.24   63.61   59.68   64.64   62.28

 

Production in 2020 was significantly lower than in 2019 due to the effects of the COVID-19 pandemic and associated production interruptions. On March 15, 2020, the Peruvian Government declared a national emergency and imposed operating business restrictions, including on the mining sector. The quarantine period was initially expected to last until the end of March 2020 but was subsequently extended up to May 10, 2020. In light of the government restrictions, Nexa suspended production at El Porvenir. During this period, mining activities were limited to critical operations with a minimum workforce to ensure appropriate maintenance, safety, and security. On May 6, 2020, the Peruvian Government announced the conditions for the resumption of operations for different sectors, including mining operations above 5,000 tpd. As a result, operations at El Porvenir, which have been suspended since March 18, 2020, restarted production on May 11, 2020, following the end of the quarantine period. Following the resumption of operations, El Porvenir ramped up production to pre-pandemic levels by June 2020.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

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Nexa holds a total of 80.16% that corresponds to the sum of Nexa’s direct interest in Nexa Resources Peru S.A.A. (0.17%) (Nexa Peru) and indirect participation of Nexa in Nexa Peru and Pampa de Cobre S.A.C. (80.06%) through its controlled company Nexa Resources Cajamarquilla S.A. (99.91%), and the remaining 19.76% are floating shares. The Mine is comprised of 25 concessions covering approximately 4,846.8 hectares (ha) and a beneficiation plant. El Porvenir’s surface properties include a 450.8 ha mine site and areas for the tailings storage facility (TSF), accommodations, and other ancillary infrastructure.

 

1.1.1 Conclusions

 

SLR has the following conclusions by area.

 

1.1.1.1 Geology and Mineral Resources

 

As of December 31, 2020, exclusive of Mineral Reserves, Measured Mineral Resources are estimated to total 0.23 million tonnes (Mt) at 2.59% Zn, 0.99% Pb, 0.23% Cu, and 63.46 g/t Ag and Indicated Mineral Resources are estimated to total 1.33 Mt at 2.93% Zn, 0.89% Pb, 0.20% Cu, and 63.33 g/t Ag. In addition, Inferred Mineral Resources are estimated to total 8.47 Mt at 3.60% Zn, 0.95% Pb, 0.23% Cu, and 78.37 g/t Ag.

 

El Porvenir has features of skarn, hydrothermal vein/breccia-style, and stratabound deposits.

 

The control of mineralization is lithological, mineralogical, and structural.

 

Protocols for drilling, sampling, analysis, verification, and security meet industry standard practices. The drill hole database was verified by SLR and is suitable for Mineral Resource estimation.

 

The geological models are reasonably constructed using available geological information and are appropriate for Mineral Resource estimation.

 

The assumptions, parameters, and methodology used for the El Porvenir Mineral Resource estimate are appropriate for the style of mineralization and proposed mining methods.

 

Nexa’s exploration strategy, practices, and procedures are in line with industry standards.

 

A number of polymetallic prospects located near the deposits have been outlined and warrant additional exploration.

 

1.1.1.2 Mining and Mineral Reserves

 

As of December 31, 2020, Proven and Probable Mineral Reserves are estimated to total 13.85 Mt at 3.75% Zn, 0.88% Pb, 0.23% Cu, and 63 g/t Ag.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

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The assumptions, parameters, and methodology used for the El Porvenir Mineral Reserve estimate meet industry standard practices and are appropriate for the style of mineralization and proposed mining methods.

 

Most of El Porvenir’s ore production comes from mechanized cut and fill (C&F), which has proven to be an effective method for mining its deposits for decades. An increasing share of the Mine’s production comes from sublevel stoping (SLS) in those areas that are suitable for the method. SLS is a lower-cost method than C&F, and provides an efficient means for disposing of development waste. According to the life of mine (LOM) plan, SLS’s share of El Porvenir’s output will increase from approximately 16% in 2021 to 46% in 2025.

 

1.1.1.3 Mineral Processing

 

Test work has been conducted in order to produce a geometallurgical model to predict metallurgical response during future processing at El Porvenir and relationships based on the ore source at El Porvenir having been derived to predict throughput, grinding media consumption, recovery, and concentrate quality.

 

Review of historical production indicates that recoveries of copper, lead, and zinc are related to their head grades, while the majority of silver is recovered to the lead concentrate.

 

Average LOM planned head grades of zinc and copper are forecast to be similar to or higher than average head grades for the past three years, while the average planned lead head grade is forecast to decrease slightly compared to recent head grades. Forecast recoveries are in line with those achieved in recent years.

 

No fundamental changes to the concentrator feed are anticipated, and in the SLR Qualified Person’s (QP) opinion, based on recent processing plant performance, the forecast recoveries and concentrate qualities for the near future are reasonable.

 

1.1.1.4 Environmental, Permitting and Social Considerations

 

No environmental issues were identified from the documentation available for review that could materially impact the ability to extract the Mineral Resources and Mineral Reserves. The El Porvenir operation complies with applicable Peruvian permitting requirements. The approved permits address the authority’s requirements for operation of the underground mine, TSFs, waste rock dumps (WRD), concentrator plant, water usage, and effluents discharge.

 

The monitoring program at El Porvenir includes meteorology, air quality, non-ionized radiation, noise, surface water quality, groundwater quality (only one location), spring water quality, effluent discharges, fauna and flora, and TSF physical stability. El Porvenir reports the results of its monitoring program to the authorities according to the frequency stated in the approved resolutions. SLR is not aware of any non-compliance issues raised by the authorities.

 

In the SLR QP’s opinion, the Environmental Management Plan for El Porvenir is adequate to address potential issues related to environmental compliance. A recommendation has been provided regarding the groundwater quality monitoring program (see Section 1.1.2.4).

 

Nexa utilizes an Integrated Dam Management System (referred to as SIGBar) for the El Porvenir TSF, which provides guidelines for document management, monitoring, evaluation, risk analysis, compliance with standards and legislation, training of personnel, operation of structures and other provisions.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

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The safety of operating a centerline raised tailings dam depends on the ability to maintain wide tailings beaches and a low phreatic level in the dam shell for stability. No issues with regard to crest settlements were noted in recent dam safety monitoring reports. SLR notes, however, that bedrock foundation grouting of the left and right abutments carried out in 2015 observed very significant grout takes in numerous grouthole stages indicating the filling of voids. A series of seepage collection sub-drainage pipes were also installed on the downstream shell of the dam prior to raising the rockfill to crest elevation 4,056 MASL. The dam monitoring consists of instrument measurements and field inspections.

 

A Mine Closure Plan has been developed for all the Mine components within the context of Peruvian legislation and is periodically updated. The most recent modification to the Mine Closure Plan and update to the closure cost estimate are from January 2020.

 

SLR’s social review indicates that, at present, Nexa’s operations at El Porvenir are a positive contribution to sustainability and community well-being. Nexa has established and continues to implement its various corporate policies, procedures, and practices in a manner consistent with relevant International Finance Corporation (IFC) Performance Standards. Nexa has, and continues to make, a positive contribution to the communities most affected by the site operations and has done a thorough job in documenting potential effects on stakeholders and protecting the rights, health, and safety of its employees.

 

In the SLR QP’s opinion the grievance mechanism in place and the Community Relations Plan, in combination with Nexa’s Social Management Policy and Nexa’s Management Procedures on negotiation for land access, monitoring of social commitments, management of social crisis, promotion of local hiring, and communication with stakeholders, are adequate to address potential issues related to local communities.

 

Nexa established commitments with the communities San Juan de Milpo and San Francisco de Asis de Yarusyacan to employ direct and indirect local workforce, dependent on employment opportunities required by the mine operations for qualified and non-qualified workforce.

 

1.1.1.5 Costs and Economic Analysis

 

The LOM operating cost forecast reflects the existing operating status of the Mine. The SLR QP has reviewed recent operating costs and is of the opinion that the forecast is appropriate for the El Porvenir operation. Nexa also continue to assess operating efficiencies and approaches in efforts to improve operating costs in the different cost centres.

 

The economics of the El Porvenir operation are positive over the LOM, confirming that the Mineral Reserves are economically viable. The economic analysis shows an after-tax net present value (NPV), at an 9% base discount rate, of $130 million.

 

1.1.2 Recommendations

 

SLR has the following recommendations by area.

 

1.1.2.1 Geology and Mineral Resources

 

1. Improve the reconciliation processes by implementing a formal procedure and forming a multi-disciplinary team to organize and analyze reconciliation results so that production data can be used to calibrate future resource and reserve models.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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2. Divide mineralization domains where groups of wireframes have been merged to avoid sharing of samples.

 

3. Review the inclusion of additional grade domains considering spatial and statistical correlations, to prevent smearing of high grades into low grade areas and vice versa.

 

4. Update the 2018 lithological model and build a litho-structural model with the main lithologies and faults that are controlling the mineralization to help define the geometry and boundaries of the mineralization. An updated lithological model would also be beneficial to evaluate and define density values by rock and by domain.

 

5. Until there is a well-established reconciliation process, monitor the silver and lead grades in the model with grade control and head grade to calibrate capping values and confirm if the higher silver and lead capping values are appropriate.

 

6. Investigate if capping levels should be applied based on high grade and low grade domains for zinc, lead, copper, and silver.

 

7. Increase the number of density samples in areas that currently have insufficient density tests available.

 

8. Use the production data to monitor the chosen drill spacing for the minor continuity zones to determine if sufficient confidence is provided to support detailed mine planning, as these domains show less grade and geological continuity.

 

9. Review and adjust resource and reserve shapes to follow the mineralization trend. Currently, there are a small number of shapes that do not follow the mineralization trend.

 

10. Re-evaluate some of the zones that were not included in the Mineral Resources and Mineral Reserves, on an ongoing basis, to potentially include part of these tonnes with continuous blocks that have the potential to be recoverable, to generate resource shapes and possibly reserve stopes.

 

11. Document all the supporting data used to define non-recoverable solids and document any changes.

 

12. Improve the survey accuracy of the mineralized mined-out stopes and development to guide the mineralization solid geometries and trends, and clean up the mined-out solids, particularly, overlapping areas.

 

13. Complete the 2021 exploration program, consisting of a 18,000 m drill program to define new Inferred Resources. The 2021 exploration program budget is approximately US$3.1 million.

 

1.1.2.2 Mining and Mineral Reserves

 

1. Consider upgrading the Mine’s underground communication system by replacing the present leaky-feeder system with a high speed digital network based on Wi-Fi or LTE technology. The upgrade would permit implementing the following:

 

Centralized control and monitoring of underground operations from a control room on surface, including real-time tracking of personnel and equipment, telemetry, ventilation on demand (VOD), seismic monitoring, and closed-circuit television, among other applications.

 

Automated and tele-remote technology to operate equipment from control stations on surface for mucking development headings during shift changes, crushing, and operating rockbreakers, among other applications.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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2. As the Mine has extensive existing workings, a private 4G-LTE network could be an attractive option. A private 4G-LTE network can provide substantial level coverage with a lower installation requirement than alternative systems as it sends a reliable signal over long distances without coaxial cables, amplifiers, or access points. Furthermore, it is not limited to line-of-site transmission.

 

1.1.2.3 Mineral Processing

 

1. Evaluate the potential benefits that may be derived from a geometallurgical model to determine whether additional test work and further development of a geometallurgical model will provide more valuable information than what is already available from test work results.

 

1.1.2.4 Environmental, Permitting and Social Considerations

 

1. Due to uncertainty regarding the potential for acid generation of the waste rock, geochemical evaluation (including static and kinetic geochemical testing on waste rock samples) should be carried out prior to closure to inform closure planning and water quality predictions for post-closure. Water quality monitoring should continue during operations to verify compliance with the national environmental standards and the appropriateness of the waste rock disposal and water management procedures that are in place.

 

2. Expand the groundwater quality monitoring program to include additional stations for collection of groundwater quality samples (and subsequent analysis). At a minimum, consideration should be given to the installation of one station upstream of the El Porvenir site.

 

3. Implement a water balance for ongoing operations to be updated by Mine personnel using meteorological and water monitored data on a regular basis (at least monthly). The water balance is an important tool to track trends and conduct short term predictions through simulation of variable operating and/or climatic scenarios to support decision making associated with tailings pond operation (e.g., maintaining adequate freeboard at all times).

 

4. Develop an integrated water balance that reflects the interaction between the El Porvenir and Atacocha operations from a water balance perspective to identify and predict possible scenarios of interruption of mine operations due to water management issues and/or dam safety concerns (e.g., not maintaining adequate dam freeboard).

 

5. Investigate opportunities for optimization of construction, tailings deposition, and water management between the Atacocha and El Porvenir operations in order to prevent situations where potential problems with one of the tailings dams could impact continuity of the sister operation.

 

6. The following recommendations are proposed for the TSF:

 

Classification of the TSF in terms of the Global Tailings Standard or the Canadian Dam Association. The classification may require more conservative design criteria in terms of flood management and seismic loading.

 

A dam breach analysis to inform the TSF classification and emergency preparedness plan.

 

A trigger alert response plan (TARP) for the piezometers for inclusion in the monitoring plan.

 

Capacity assessments of the TSF completed on a bi-annual basis with topographic and bathymetric surveys.

 

Complete long term geochemical kinetic testing of the tailings.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

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Implement a groundwater monitoring program at the TSF to determine levels of metals and sulphates.

 

Monitor the water quality from the TSF subsurface drains.

 

1.1.2.5 Costs and Economic Analysis

 

1. Continuously monitor costs and lock in costs as soon as possible to eliminate economic uncertainty.

 

2. Continue efforts towards improving efficiencies and approaches to mining and development operations as opportunities arise in these areas.

 

1.2 Economic Analysis

 

The economic analysis contained in this Technical Report Summary is based on the Mineral Reserves, economic assumptions provided by Nexa for El Porvenir, and the capital and operating costs as presented below.

 

1.2.1 Economic Criteria

 

1.2.1.1 Physicals

 

Mine life: 8 years (between 2021 and 2028):

 

Underground ore tonnes mined:         13.85 Mt

 

Cu grade:               0.23%Cu

 

Zn grade:               3.75% Zn

 

Pb grade:               0.88% Pb

 

Ag grade:              62.8 g/t Ag

 

Processed:

 

Total Ore Feed:    13.85 Mt

 

Cu grade:       0.23% Cu

 

Zn grade:       3.75% Zn

 

Pb grade:       0.88% Pb

 

Ag grade:      62.8 g/t Ag

 

Contained Metal:

 

Cu:                 31,500 t Cu

 

■  Zn:                 518,900 t Zn

 

■  Pb:                  122,400 t Pb

 

■  Ag:                 27.966 million ounces (Moz) Ag

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

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Average LOM Recoveries:

 

Cu recovery                         14.3%

 

Zn recovery                         89.5%

 

Pb recovery                         78.8%

 

Ag in Cu recovery              3.8%

 

Ag in Zn recovery              14.6%

 

Ag in Pb recovery              59.1%

 

Recovered Metals:

 

Cu:                  4,500 t Cu

 

■  Zn:                  464,700 t Zn

 

■  Pb:                  96,800 t Pb

 

■  Ag:                 21.676 Moz Ag

 

Payable Metals:

 

■  Cu:                  4,300 t Cu

 

■  Zn:                  390,700 t Zn

 

■  Pb:                  91,200 t Pb

 

■  Ag:                 16.664 Moz Ag

 

1.2.1.2 Revenue

 

Revenue is estimated based on the following LOM weighted average metal prices:

 

Cu price:                US$6,388/t Cu

 

Zn price:                US$2,511/t Zn

 

Pb price:                US$1,977/t Pb

 

Ag price:               US$17.20/oz Ag

 

Net Revenue includes the benefit of additional US$128.7/t Zn selling price and zinc smelting at cost (rather than at commercial third-party terms), due to integration with Nexa’s Cajamarquilla refinery.

 

Logistics, Treatment (TC), and Refining (RC) charges:

 

LOM average Transportation/Logistics charges:

 

Cu concentrate: US$127.05/t concentrate for export

 

Zn concentrate: US$38.03/t concentrate to Cajamarquilla refinery

 

Pb concentrate: US$123.84/t concentrate for export

 

Treatment Charges:

 

TC+RC Cu concentrate: US$111.68/t concentrate

 

TC Zn concentrate for export: US$238.72/t concentrate

 

TC Pb concentrate: US$201.68/t concentrate

 

Refined Zn conversion costs at Cajamarquilla: US$509.73/t

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

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Refining Charges:

 

Ag in Cu concentrate: US$0.50/oz

 

Ag in Pb concentrate: US$1.00/oz

 

Net Smelter Return (NSR) Revenue after logistics, treatment, and refining charges is US$1,306 million.

 

1.2.1.3 Capital Costs

 

LOM sustaining capital costs of US$221.1 million.

 

Closure costs of US$25.2 million were included at the end of the Mineral Reserves based LOM in year 2029.

 

1.2.1.4 Operating Costs

 

LOM unit operating cost average of:

 

Mine Development: US$6.56/t mined

 

Underground Mining: US$32.81/t mined

 

Processing: US$12.72/t milled

 

General and administrative (G&A): US$7.30/t milled

 

Total unit operating costs of US$59.39/t milled.

 

LOM operating costs of US$822.5 million.

 

1.2.1.5 Taxation and Royalties

 

Corporate tax rate in Peru is 29.50%.

 

Special Mining Tax (IEM/GEM) LOM average rate: 4.3%.

 

Mining royalties LOM average rate: 4.3%.

 

Employees participation: 8%.

 

SLR has relied on a Nexa taxation model for calculation of income taxes applicable to the cash flow.

 

1.2.2 Cash Flow Analysis

 

SLR developed a LOM after-tax cash flow model for El Porvenir to confirm the economics of the LOM plan. The model is based on Nexa’s TR EP 2020 v6 Final model. The model does not take into account the following components:

 

Financing costs

 

Insurance

 

Overhead cost for a corporate office

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

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The economic analysis confirmed that the El Porvenir Mineral Reserves are economically viable. The pre-tax NPV at a 9% discount rate is US$155 million and the after-tax NPV at a 9% discount rate is US$130 million.

 

A cash flow summary is presented in Table 1-2. All costs are in Q4 2020 US dollars with no allowance for inflation.

 

Table 1-2: After-Tax Cash Flow Summary

Nexa Resources S.A. – El Porvenir Mine

 

    Units   Total LOM
Production        
LOM   years   8
UG Production   000 tonnes   13,850
Ag Grade   g/t   2.02
Cu Grade   %   0.23%
Pb Grade   %   0.88%
Zn Grade   %   3.75%
Concentrate Production        
Cu Concentrate   dmt   22,662
Pb Concentrate   dmt   185,932
Zn Concentrate   dmt   925,961
Recovered        
Ag   oz   21,676,261
Cu   tonnes   4,496
Pb   tonnes   96,796
Zn   tonnes   464,740
Metal Prices        
LOM average - Ag   US$/oz   17.20
LOM average -  Cu   US$/tonne   6,388
LOM average -  Pb   US$/tonne   1,977
LOM average -  Zn   US$/tonne   2,511
Cash Flow        
Gross Revenue   US$ million   1,652,150
Transport / TC-RC  Charges   US$ million   (345,843)
Royalties   US$ million   (19,648)
Net Revenue   US$ million   1,286,659
Operating Costs        
Mining Costs   US$ million   (545,237)
Processing Costs   US$ million   (176,174)
G&A   US$ million   (101,109)

 

 

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    Units   Total LOM
Other Costs   US$ million   (10,624)
Operating Cash Flow   US$ million   453,516
Direct Capital Costs   US$ million   -
Sustaining Capital Costs   US$ million   (221,075)
Reclamation & Closure   US$ million   (25,196)
Change Working Capital   US$ million   -
Pre-Tax Net Cash Flow   US$ million   207,245
Taxes - Income Tax   US$ million   (28,339)
Taxes - IEM/GEM   US$ million   (2,541)
After-Tax Cashflow   US$ million   176,364
Project Economics        
Pre-Tax        
Pre-tax NPV at 7%   US$ million   164,845
Pre-tax NPV at 8%   US$ million   159,759
Pre-tax NPV at 9%   US$ million   154,883
After-Tax        
After-Tax NPV at 7%   US$ million   139,026
After-Tax NPV at 8%   US$ million   134,246
After-tax NPV at 9%   US$ million   130,143

 

1.2.3 Sensitivity Analysis

 

SLR conducted cash flow sensitivity analyses on after-tax NPV at a 9% discount rate, to identify project risks, using metal prices, head grade, metallurgical recovery, capital costs, and operating costs.

 

The Mine after-tax NPV is most sensitive to metal prices and head grade, followed by metallurgical recovery, operating costs, and capital costs.

 

1.3 Technical Summary

 

1.3.1 Property Description and Location

 

The El Porvenir mining operation is located in Peru’s Central Andes region at an elevation of approximately 4,200 MASL. The Mine is situated in the districts of San Francisco de Asís de Yarusyacán and Yanacancha, in the province and department of Pasco. El Porvenir is located 13 km from the city of Cerro de Pasco, which is located approximately 315 km by road from the national capital, Lima, when travelling by the Carretera Central and the La Oroya-Huánuco highway.

 

1.3.2 Land Tenure

 

El Porvenir’s mineral rights consist of 25 mining concessions covering an area of 4,846.77 ha and one beneficiation concession. None of these concessions are in urban expansion areas, protected natural areas, or archaeological sites. These concessions are subject to annual fees and penalties. Nexa reports that all fees and penalties have been paid in full up to 2020. Most of the concessions are subject to royalties according to a lease agreement signed on January 2, 2006.

 

 

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1.3.3 History

 

El Porvenir has a long history in the Peruvian mining sector, extending over 70 years. The Mine began operating as a small-scale artisanal mine in 1949, and Compañía Minera Milpo S.A. (Milpo) was incorporated the same year to operate the Mine. A gravity separation plant was built at the site in 1953, and a flotation plant was completed in 1979. The Mine’s output increased steadily over the decades, attaining its current production rate of approximately 5,600 tpd in 2014. Milpo acquired the adjacent Atacocha Mina in 2008. In 2010, Nexa, then Grupo Votorantim, gained control of Milpo and its assets, including El Porvenir. In 2014, Nexa company began integrating the El Porvenir and Atacocha operations, including administration, the TSFs, and the electrical power supply. El Porvenir’s operations were interrupted from March 10, 2020 to May 15, 2020, due to the COVID-19 pandemic.

 

1.3.4 Geology and Mineralization

 

El Porvenir is situated in the Pasco region of the Western Cordillera of the Andes, within the Eocene-Miocene Polymetallic and Miocene Au-Ag Epithermal Belts.

 

Within the property area, the stratigraphic units of primary interest are the Pucará and the Goyllarisquizga groups. The Goyllarisquizga Group outcrops in the area of the deposit comprising quartz rich sandstone, corresponding to the Goyllarisquizga Formation. Sandstones may vary from quartz arenite to arkose. The matrix is argillaceous to siliceous. Above the 4000 Level, the lithology and stratification are well defined and easy to recognize. Below the 4000 Level, strong alteration has obliterated the original rock intensity forming siliceous breccias and massive silica where it is still possible to recognize quartz grains and in few places the stratification.

 

Intrusive rocks within the property are variably porphyritic dacite to quartz diorite with hornblende and biotite phenocrysts. The Milpo-Atacocha fault is a major structural feature in the region, which can be traced for nearly 15 km from Yarusyacán in the north to Carmen Chico in the south.

 

Mineralization is characterized as a skarn, intermediate sulphidation epithermal vein/breccia-style, or stratabound mineralization in the Goyllarisquizga Formation:

 

Skarn-related mineralization is commonly associated with the garnet and silica-skarn-chlorite assemblages, comprising pyrite, chalcopyrite, sphalerite, galena and minor pyrrhotite, pyrite, bornite, covellite, orpiment, and realgar within the Pucará Group sediments around the Milpo stock.

 

The silica breccia consists of sub-rounded to sub-angular white to milky grey opaline silica clasts, millimetres to centimetres in size, and to a lesser extent, sandstone, and limestone clasts. The silica breccia clasts are cemented by white granular silica, with occasional cross-cutting veins of white silica. Breccias include massive (siliceous) breccias, granular (siliceous) breccias, and Ag-Pb-Zn breccias sub-divided into calcareous, polymictic-monomictic, and karst (collapse). Breccia clasts include limestone, marble, silica (massive), and skarn; the composition of the clasts indicates that brecciation occurred later than skarn development.

 

The stratabound Pb-Ag-Zn mineralization occurs in the sandstone strata (mantos) at the base of the Goyllarizquisga Formation (near the contact with the Pucará Group). Several disseminated sulphide mantos have recently been identified at Sara and Porvenir 2W within the quartz sandstone, generally in contact with layers of silt and microconglomerates. The minerals include galena with silver content, sphalerite, and pyrite. Gold is also present.

 

 

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1.3.5 Exploration Status

 

As of February 15, 2020, a total of 4,664 drill holes totalling 762,848.57 m, have been completed at El Porvenir. Nexa’s exploration program is based on an integrated strategy of geological and structural interpretation, combined with remote sensing for alteration and magnetic patterns and anomalies. The 2020 exploration program, including an additional 36 drill holes totalling 14,246.80 m, confirmed the continuity of the mineralization at Sara, and the magnetometry program defined five geophysical anomalies (Tingo, Carmen Chico NW, Carmen Chico W, La Quinua, and Chicri), which will be studied through mapping programs, surface sampling, and diamond drilling in the next three years. Based on surface mapping, remote sensing and geophysics, six brownfield exploration projects were defined (Machcan, Curiajasha, Longreras, Manuel 05 and Pique Estrella, La Churca, and La Quinua Chicrin Corridor). The exploration work planned for 2021 involves a budget of $3.1 million, and includes 18,000 m of diamond drilling, focused on defining new Mineral Resources in the Sara corridor, comprising the eastern part of the Milpo syncline in the Goyllarisquizga Formation, and the Integration Zone at the 3,300 Level of the Mine.

 

1.3.6 Mineral Resources

 

The Mineral Resources in El Porvenir are contained in four zones: Zona Alta (Upper Zone), Zona Intermedia (Intermediate Zone), Zona Baja (Lower Zone), and Profundizacion Zona (Mine Deepening Zone).

 

The Mineral Resource estimate for El Porvenir, as of December 31, 2020, is summarized in Table 1-3. Mineral Resources have been classified in accordance with the definitions for Mineral Resources in S-K 1300, which are consistent with Canadian Institute of Mining, Metallurgy and Petroleum (CIM) Definition Standards for Mineral Resources and Mineral Reserves dated May 10, 2014 (CIM (2014) definitions.

 

Table 1-3: Summary of Mineral Resources – December 31, 2020

Nexa Resources S.A. – El Porvenir Mine

 

    Tonnes   Grade   Contained Metal
Category   (Mt)   (% Zn)   (% Pb)   (% Cu)   (g/t Ag)   (000 t Zn)   (000 t Pb)   (000 t Cu)   (000 oz Ag)
Measured   0.23   2.59   0.99   0.23   63.46   6.0   2.3   0.5   471
Indicated   1.33   2.93   0.89   0.20   63.33   39.0   11.9   2.6   2,715
M+I   1.56   2.87   0.91   0.20   63.35   45.0   14.2   3.2   3,186
Inferred   8.47   3.60   0.95   0.23   78.37   305.0   80.8   19.8   21,345

 

Notes:

 

1. The definitions for Mineral Resources in S-K 1300 were followed for Mineral Resources, which are consistent with CIM (2014) definitions.

2. Mineral Resources are reported on a 100% ownership basis. Nexa owns an 80.16% interest.
3. Mineral Resources are estimated at NSR cut-off values of US$60.06/t for the Upper Zone, US$61.09/t for the Intermediate Zone, US$59.75/t for the Lower Zone, and US$63.37/t for the Mine Deepening Zone for C&F resource shapes.
4. Mineral Resources are estimated using an average long term metal prices of Zn: US$2,869.14/t (US$1.30/lb); Pb: US$2,249.40/t (US$1.02/lb); Cu: US$7,426.59/t (US$3.37/lb); and Ag: US$19.38/oz, and metallurgical recoveries are based on recovery curves derived from historical processing data.

 

 

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5. A minimum mining width of 4.0 m was used for C&F resource shapes.

6. Bulk density varies depending on mineralization domain.
7. Mineral Resources are exclusive of Mineral Reserves.
8. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability.
9. Numbers may not add due to rounding.

 

The SLR QP is of the opinion that, with consideration of the recommendations summarized in this section, any issues relating to all relevant technical and economic factors likely to influence the prospect of economic extraction can be resolved with further work.

 

The Mineral Resource estimate was completed using Datamine Studio RM and Leapfrog Geo software. Wireframes for geology and mineralization were constructed in Leapfrog Geo based on geology sections, assay results, lithological information, underground mapping, and structural data. Assays were capped to various levels based on exploratory data analysis and then composited to two metre lengths. Wireframes were filled with blocks and sub-celling at wireframe boundaries. Blocks were interpolated with grade using ordinary kriging (OK) and inverse distance cubed (ID3) interpolation algorithms. Block estimates were validated using industry standard validation techniques. Classification of blocks used distance-based and mineralization continuity criteria.

 

Mineral Resources at El Porvenir are reported using all the material within resource shapes generated in Deswik Stope Optimizer (DSO) software, satisfying minimum mining size, NSR cut-off values of US$60.06/t for the Upper Zone, US$61.09/t for the Intermediate Zone, US$59.75/t for the Lower Zone, and US$63.37/t for the Mine Deepening Zone for C&F resource shapes, and continuity criteria.

 

1.3.7 Mineral Reserves

 

Table 1-4 presents an updated Mineral Reserve estimate effective December 31, 2020 prepared by Nexa and reviewed by SLR. This Mineral Reserve estimate complies with CIM (2014) definitions, which are consistent with the definitions for Mineral Reserves in S-K 1300 Subpart 229.1300. Measured and Indicated Mineral Resources were converted into Proven and Probable Mineral Reserves, respectively.

 

Dilution and NSR cut-off values were two critical factors used in the Mineral Reserve estimate. Dilution includes waste originating from internal and planned sources. The NSR cut-off values vary with the mining zones, the mining method, and whether a block is considered marginal.

 

The Mineral Reserves are grouped into four mining zones, and the mining methods are mechanized C&F and SLS. The NSR calculations consider the metal grades of the mining blocks, metal prices, metallurgical recoveries, commercial terms and conditions, and mining, processing, and G&A costs. The payable metals in concentrates include concentrate treatment, transportation, refining charges, deductions, and penalties. The prices are based on 10 year averages of London Metal Exchange (LME) projections.

 

 

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Table 1-4: Mineral Reserves –December 31, 2020

Nexa Resources S.A. – El Porvenir Mine

 

    Tonnes   Grade   Contained Metal
Category   (000 t)   (% Zn)   (% Pb)   (% Cu)   (g/t Ag)   (000 t Zn)   (000 t Pb)   (000 t Cu)   (000 oz Ag)
Proven   3,764   3.76   0.98   0.25   62.9   141.3   36.9   9.5   7,602
Probable   10,086   3.74   0.85   0.22   62.8   377.6   85.5   22.4   20,364
Total   13,850   3.75   0.88   0.23   62.8   518.9   122.4   31.9   27,966

 

Notes:

 

1. The definitions for Mineral Reserves in S-K 1300 were followed for Mineral Reserves which are consistent with CIM (2014) definitions.
2. Mineral Reserves are reported on a 100% ownership basis. Nexa owns an 80.16% interest.
3. Mineral Reserves are estimated at cut-off grades depending on the zone and mining method.
4. Mineral Reserves are estimated using average long term prices of Zn: US$2,494.90/t (US$1.13/lb); Pb: US$1,956.00/t (US$0.89/lb); Cu: US$6,457.90/t (US$2.93/lb); Ag: US$16.85/oz.
5. A minimum mining width of 5 m was used.
6. Density is 3.12 t/m3.
7. Numbers may not add due to rounding.

 

The SLR QP is not aware of any risk factors associated with or changes to any aspect of the modifying factors such as mining, metallurgical, infrastructure, permitting, or other relevant factors that could materially affect the Mineral Reserve estimate.

 

1.3.8 Mining Method

 

El Porvenir mined 2.11 Mt of zinc-lead-copper ore in 2019 and 1.52 Mt in 2020. Dilution accounted for 34% of the ore tonnage produced. Mine production is presently underway in the Upper Zone, the Intermediate Zone, the Lower North Zone, and the Lower West (El Porvenir 9) Zone.

 

El Porvenir uses two mining methods: mechanized overhand C&F and SLS. C&F is the predominant method, accounting for over 80% of the mine’s production. El Porvenir uses a version of SLS called Avoca, also referred to as longitudinal longhole retreat mining.

 

C&F and SLS have similar development requirements as they both involve dividing a mining zone into horizons between sublevels and excavating the ore in an ascending fashion. Sublevels are typically spaced at 20 m vertical intervals and accessed via spiral ramps. The development on each sublevel includes an access drift, a footwall drive, and crosscuts or attack ramps, which provide access to the orebody. For SLS, the footwall drive can be as close as 15 m from the footwall contact, whereas for C&F, the footwall drives have to be offset from it by 60 m to provide sufficient distance for fanning the attack ramps.

 

The geotechnical conditions at El Porvenir result from the rock mass’s characteristics and the Mine’s depth. The host rock and the mineralized zones are generally classified as fair to good, with rock mass ratings (RMR) ranging from 40 to 60. El Porvenir is one of South America’s deepest mines, extending more than 1,800 m below the main access level. Its depth contributes to the occurrence of seismic events, including rockbursts.

 

Table 1-5 presents the LOM production schedule broken down by metal grades on an annual basis until 2028. Mine output remains stable at present levels until 2024 but then declines progressively in subsequent years.

 

 

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Table 1-5: Mine Production Schedule

Nexa Resources S.A. – El Porvenir Mine

 

    Units   Total   2021   2022   2023   2024   2025   2026   2027   2028
Ore Total   000 t   13,850   2,161   2,222   2,220   2,036   1,658   1,380   1,371   802
Stopes   000 t   12,743   2,001   2,008   2,029   1,879   1,524   1,270   1,309   724
Develop   000 t   1,107   160   214   191   157   134   110   62   79
Zn   %   3.75   3.28   3.69   3.57   3.82   4.11   4.25   4.01   3.39
Pb   %   0.88   1.12   0.92   1.02   0.96   0.71   0.67   0.66   0.70
Cu   %   0.23   0.17   0.21   0.24   0.25   0.24   0.27   0.28   0.21
Ag   g/t   62.8   72.5   61.6   66.6   61.9   52.3   56.6   59.1   70.0
NSR   US$/t   98.54   95.91   97.27   98.20   100.48   99.56   103.22   99.99   92.61

 

1.3.9 Mineral Processing

 

El Porvenir processing plant is located adjacent to the Mine at an altitude of 4,100 MASL to 4,200 MASL. The concentrator has an ore processing capacity of approximately 2.2 Mtpa. El Porvenir copper and lead concentrates are sold to traders and delivered by road and rail to Callao (approximately 270 km by road) for shipping overseas, while zinc concentrate is transported by road and rail to Nexa’s Cajamarquilla zinc refinery east of Lima. El Porvenir is approximately 315 km from Lima by road. The current LOM plan continues to 2028. Processing consists of conventional crushing, grinding, and flotation to produce separate copper, lead, and zinc concentrates.

 

Tailings are cycloned and the coarse fraction is used for mine backfill, which constitutes approximately 50% of tailings produced. Water from tailings dewatering is returned to the process. Overflow from the cyclones containing the fine tailings is deposited in the conventional TSF adjacent to the Mine and processing plant. Tailings can be discharged at various points in the TSF by means of valved discharge points on the tailings line. Clarified water discharged from the TSF joins natural water flows.

 

Make-up water is supplied from various streams around the TSF, as well as the Carmen Chico River, approximately 3.2 km south of the processing facility.

 

El Porvenir lead and zinc concentrates are generally clean and do not attract penalty charges for deleterious elements. The copper concentrate attracts penalties due to elevated lead and zinc content (approximately 15% to 20% combined). The penalty charges are approximately US$17.00/dmt.

 

1.3.10 Infrastructure

 

The El Porvenir infrastructure consists of the following facilities:

 

Approximately 6,000 tpd underground mine

 

A 2.2 Mtpa processing plant with associated laboratory and maintenance facilities

 

Power plant

 

Access roads

 

Offices and warehouses

 

 

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Accommodations

 

Waste rock facilities

 

Temporary ore stockpiles

 

Hydraulic backfill plant

 

TSF

 

The power supply for the Mine comes from two sources, the national power grid and the La Candelaria Hydroelectric Plant.

 

Raw water is sourced from Tingovado Creek, as well as from other creeks around the TSF. Fresh water supply is obtained from the Carmen Chico River, approximately 3.2 km south of the processing facility.

 

The EL Porvenir TSF receives tailings generated by both El Porvenir and the Atacocha concentrator plants. A portion of tailings is used for hydraulic backfill at El Porvenir. The TSF was originally constructed in the 1970s, and the current elevation of the dam crest is 4,060 MASL and the dam height is 140 m.

 

Waste rock from the underground operations is either used as backfill underground or stockpiled on surface. If waste rock is brought to surface in the future, it will be deposited in a designated area near the secondary TSF embankment southwest of the concentrator plant area.

 

1.3.11 Market Studies

 

The principal commodities produced at El Porvenir, zinc, lead, copper, and silver, are freely traded, at prices and terms that are widely known, so that prospects for sale of any Nexa production are virtually assured. El Porvenir is an operating mine with concentrate sales contracts in place for copper and lead concentrates, while zinc concentrate is consumed by Nexa’s Cajamarquilla smelter according to their internal planning.

 

Market information is based on the industry scenario analysis prepared by Nexa’s Market Intelligence team in July 2020 using information sourced from different banks and independent financial institutions, economy and politics research groups, and metals consultants.

 

1.3.12 Environmental and Social Considerations

 

El Porvenir has a net positive water balance that results in surplus water collected on-site being discharged from the TSF to the receiving environment through a decant structure. Clean (non-contact) surface runoff water is managed through upstream diversion ditches that prevent its entrance to the TSF, and convey it downstream to the Lloclla River, a tributary of the Huallaga River. Contact water collected in the tailings pond is recycled via a decant pumping system to the concentrator plant for use in the process. A lined seepage collection monitoring pond is located at the downstream toe of the main embankment of the TSF.

 

The El Porvenir TSF (originally constructed in the 1970s) receives tailings generated by both Atacocha and El Porvenir concentrator plants. A portion of tailings is used for hydraulic backfill at El Porvenir. The tailings disposal is performed in subaerial conditions which allows a beach with a gentle slope towards the water or supernatant pond (settling pond). The tailings discharge locations allow for the settling pond to be centrally located within the TSF and a tailings beach to form in front of the main embankment.

 

Various Environmental Impact Assessments (EIA) and supporting technical reports have been submitted and approved between 2001 and 2020 to identify potential environmental effects resulting from project activities for the construction, operation, and closure stages. The most recent modification of the EIA was approved by the Peruvian authorities in 2012 to grant authorization for a maximum production rate of 7,500 tpd. The most recent update of the environment management plan was presented in the sixth supporting technical report issued in 2020. The monitoring program implemented at the Mine includes monitoring of meteorology, air quality, non-ionizing radiation, noise, surface water quality, springs water quality, effluent discharges, fauna and flora, and physical stability of the tailings dam. The results of the monitoring program for air quality, ambient noise, non-ionizing radiations, and water quality are reported to the Peruvian authorities quarterly.

 

 

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El Porvenir holds a number of permits in support of the current operations. The permits are Directorial Resolutions issued by the Peruvian authorities upon approval of mining environmental management instruments filed by the mining companies. Nexa maintains an up to date record of the legal permits obtained to date.

 

The communities located within the area of influence of the Mine are:

 

Comunidad de San Francisco de Asís de Yarusyacán (20 Anexos)

 

Comunidad de Titaclayán

 

Comunidad de Cajamarquilla

 

Comunidad de Malauchaca

 

Comunidad Santa Rosa de Pitic

 

Comunidad San Miguel

 

Comunidad La Candelaria

 

Centro Poblado La Quinua

 

Comunidad 30 de Agosto

 

Comunidad San Juan de Yanacachi

 

Comunidad San Juan de Jarapampa

 

Cooperativa Pucayacu

 

Nexa adheres to international standards to provide best practices for public reporting on economic, environmental, and social impacts in order to help Nexa and its shareholders and stakeholders understand their corporate contribution to sustainable development. Corporately, Nexa has made several commitments to improve community health and safety as well as the overall well-being of community members.

 

A conceptual Mine Closure Plan was approved in 2007 for the Mine components within the context of the Peruvian legislation and has subsequently been amended or updated four times. The Mine Closure Plan addresses temporary, progressive, and final closure actions, and post-closure inspection and monitoring. A closure cost estimate was developed and included in the Mine Closure Plan. The total financial assurance for progressive closure, final closure, and post-closure is calculated by Nexa according to the Peruvian regulations (Supreme Decree D.S. N° 262-2012-MEM/DM).

 

1.3.13 Capital and Operating Costs

 

The capital costs for the Mine are shown in Table 1-6. El Porvenir is an operating mine, hence all capital costs are considered sustaining cost.

 

 

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Table 1-6: Life of Mine Capital Budget

Nexa Resources S.A. – El Porvenir Mine

 

Cost
(US$000)
  Total   2021   2022   2023   2024   2025   2026   2027   2028
Tailing Dam & Waste Deposit                                    
Raising   53,858   10,808   18,149   24,900   -   -   -   -   -
New Dam   13,246   2,700   1,000   -   5,000   4,546   -   -   -
Tailing Treatment   3,782   3,782   -   -   -   -   -   -   -
Heavy Mobile Equipment                                    
Replacement   23,284   1,838   50   3,567   4,781   5,593   3,641   3,815   -
Addition   3,335   850   1,600   -   -   -   -   -   -
Asset Integrity                                    
Asset Integrity – Plant   11,365   6,605   2,805   475   575   705   100   100   -
Asset Integrity – Mine   150   -   -   -   -   150   -   -   -
Other Sustaining                                    
Others   1,340   110   550   250   290   100   0   40   -
Civil Construction   200   200   -   -   -   -   -   -   -
Mining Facilities                                    
Communication system   2,450   550   700   600   300   300   -   -   -
Pumping   2,500   700   300   300   300   300   300   300   -
Electrical Substation   1,650   1,000   200   450   -   -   -   -   -
Ventilation / Cooling   950   100   150   100   150   150   150   150   -
Operation Unit Projects                                    
Improvements   4,631   1,821   1,110   1,700   -   -   -   -   -
Audit & Inspection   2,380   390   890   1,100   -   -   -   -   -
Other Expenditures                                    
Expansion Projects   -   -   -   -   -   -   -   -   -
Information Technology   1,020   480   150   130   130   130   -   -   -
Automation Project   2,190   874   1,166   150   -   -   -   -   -
Mine Development Capital Cost                                    
Underground Mine Development   92,745   17,170   16,073   16,941   18,954   13,124   6,521   1,934   2,030
Total   221,075   49,977   44,894   50,663   30,479   25,982   10,712   6,338   2,030

 

The Mine Closure Plan was prepared to meet the Peruvian national requirements with the closure and reclamation cost assessed at US$25.2 million.

 

Table 1-7 presents El Porvenir operating costs based on a LOM period of eight years.

 

 

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Table 1-7: Operating Budget

Nexa Resources S.A. – El Porvenir Mine

 

All-In Cost
(US$000)
  Total   2021   2022   2023   2024   2025   2026   2027   2028
Mine Underground   454,350   63,077   64,320   64,742   61,913   55,796   51,610   51,569   41,323
High Zone C&F   127,409   22,074   19,242   20,828   15,955   8,275   13,293   13,374   14,369
High Zone SLS   4,947   301   1,818   2,354   473   -   -   -   -
Intermediate C&F   49,425   19,329   11,914   12,146   4,161   1,874   -   -   -
Intermediate SLS   90,866   8,801   11,734   11,978   21,170   17,064   3,651   3,673   12,795
Low Zone C&F   30,666   11,827   11,445   4,944   13   861   1,577   -   -
Low Zone SLS   8,855   636   366   797   3,358   3,698   -   -   -
Deepening C&F   98,132   -   5   5,621   15,239   19,778   21,641   23,630   12,218
Deepening SLS   44,050   109   7,795   6,074   1,546   4,246   11,448   10,892   1,941
Processing   176,174   23,274   23,452   23,446   22,910   21,808   20,998   20,972   19,314
G&A   101,109   15,774   16,219   16,206   14,861   12,103   10,076   10,011   5,858
Development Operating Cost   90,887   17,162   15,971   14,837   13,065   10,602   8,673   6,244   4,332
Total   822,519   119,288   119,961   119,231   112,750   100,309   91,356   88,797   70,827

 

 

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2.0 Introduction

 

SLR Consulting Ltd (SLR) was retained by Nexa Resources S.A. (Nexa) to prepare an independent Technical Report Summary on the El Porvenir Mine (the Mine or El Porvenir), located in Pasco Province, central Peru. The purpose of this Technical Report Summary is to support the public disclosure of updated Mineral Reserve and Mineral Resource estimates. This Technical Report Summary conforms to United States Securities and Exchange Commission’s (SEC) Modernized Property Disclosure Requirements for Mining Registrants as described in Subpart 229.1300 of Regulation S-K, Disclosure by Registrants Engaged in Mining Operations (S-K 1300) and Item 601 (b)(96) Technical Report Summary.

 

Nexa is a publicly traded company on the Toronto Stock Exchange (TSX) and the New York Stock Exchange (NYSE). Nexa is a reporting issuer in all provinces and territories of Canada and is under the jurisdiction of the Ontario Securities Commission.

 

Nexa is a large-scale, low-cost, integrated zinc producer with over 60 years of experience developing and operating mining and smelting assets in Latin America. Nexa has a diversified portfolio of polymetallic mines (zinc, lead, copper, silver, and gold) and also greenfield projects at various stages of development in Brazil and Peru. In Brazil, Nexa owns and operates two underground mines, Vazante and Morro Agudo (Zn and Pb). It also operates two zinc smelters in Brazil (Três Marias and Juiz de Fora). In Peru, Nexa operates the El Porvenir (Zn, Pb, Cu, and Ag), Cerro Lindo (Zn, Cu, Pb, and Ag), and Atacocha (Zn, Pb, Au, and Ag) mines, as well as the Cajamarquilla zinc smelter near Lima. Nexa’s development projects in Peru include Magistral, Shalipayco, Florida Canyon (JV with Solitario), Hilarión, and Pukaqaqa. In Brazil, Nexa is developing the Aripuanã Zinc Project (Zn, Pb, Cu, Au and Ag), which is currently under construction and is owned by Mineração Dardanelos Ltda. (Dardanelos), a wholly-owned subsidiary of Nexa.

 

El Porvenir began operations as a small-scale artisanal mine in 1949. The operation’s capacity increased almost continuously over the decades, and in 2012, its production reached its current capacity of approximately 6,000 tonnes per day (tpd) in 2013, Nexa commenced the process of integrating the El Porvenir and Atacocha mining operations. To date, integration has been achieved for the administrative function, the electric power supply, and the tailings facility. El Porvenir comprises 25 mining concessions (totalling 4,846.77 ha) and a beneficiation concession, located in the districts of San Francisco de Asís de Yarusyacán and Yanacancha, province and department of Pasco in Peru.

 

Nexa holds a total of 80.16% that corresponds to the sum of Nexa’s direct interest in Nexa Resources Peru S.A.A. (0.17%) (Nexa Peru) and indirect participation of Nexa in Nexa Peru and Pampa de Cobre S.A.C. (80.06%) through its controlled company Nexa Resources Cajamarquilla S.A. (99.91%), and the remaining 19.76% are floating shares.

 

2.1 Site Visits

 

An SLR geologist, mining engineer, and metallurgical engineer, all of whom are Qualified Persons (QP), visited the site from September 5 to 7, 2018.

 

2.2 Sources of Information

 

During the preparation of this Technical Report Summary and the site visit, discussions were held with the following personnel from Nexa:

 

Thiago Nantes Teixeira, Manager of Internal Commission of Resources and Reserves

 

 

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Priscila Artioli, Internal Commission of Resources and Reserves

Fernando Madeira Perisse, Technical Services Manager

Paulo Henrique Araujo Calazans, Mining Engineer

Eliott Hidalgo, Resource Chief – Nexa Peru

Nydia Mendizabal, Database Administrator at El Porvenir

Daniel Arias, Modeller Geologist

Daniel Saenz, Modeller Geologist – Anglo Peruana Terra

Carlos Uchuquicaña, Chief Geologist at El Porvenir

José Antonio Lopes, Corporate Resource Manager

Cristian Mendoza, Exploration Chief Geologist

Mervin Tapia, Brownfield Exploration Manager

Roberto Bados, Geology Manager at El Porvenir

Philipe Innecco Rosa, Mine Planning Engineer

Paulo Henrique Calazans, Mine Planning Consultant

Jorge Carbajal Diéguez, Corporative Planning Engineer – Long Term

Julio Cesar Luna Caballero, Technical Services Manager

Milena Alves Moreira, Environmental Manager

Jose Madrid, Environmental Chief – El Porvenir

Walter Heredia, Social Management Manager

Miluska Minaya, Community Relationship Coordinator

Camila Silva, Metallurgical Plant Chief

Juliana Siqueira, Metallurgical Plant Manager

Julio Cesar Luna Caballero, Technical Services Manager

 

The documentation reviewed and other information sources of information are listed in Section 24 (References) at the end of this Technical Report Summary.

 

2.3 List of Abbreviations

 

Units of measurement used in this report conform to the metric system. All currency in this report is US dollars (US$) unless otherwise noted.

 

μ micron kVA kilovolt-amperes
μg microgram kW kilowatt
a annum kWh kilowatt-hour
A ampere L litre
bbl barrels lb pound
Btu British thermal units L/s litres per second
°C degree Celsius m metre
C$ Canadian dollars M mega (million); molar
cal calorie m2 square metre

 

 

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cfm cubic feet per minute m3 cubic metre
cm centimetre MASL metres above sea level
cm2 square centimetre m3/h cubic metres per hour
d day mi mile
dia diameter min minute
dmt dry metric tonne μm micrometre
dwt dead-weight ton mm millimetre
°F degree Fahrenheit mph miles per hour
ft foot MVA megavolt-amperes
ft2 square foot MW megawatt
ft3 cubic foot MWh megawatt-hour
ft/s foot per second oz Troy ounce (31.1035 g)
g gram oz/st, opt ounce per short ton
G giga (billion) ppb part per billion
Gal Imperial gallon ppm part per million
g/L gram per litre psia pound per square inch absolute
Gpm Imperial gallons per minute psig pound per square inch gauge
g/t gram per tonne RL relative elevation
gr/ft3 grain per cubic foot s second
gr/m3 grain per cubic metre st short ton
ha hectare stpa short ton per year
hp horsepower stpd short ton per day
hr hour t metric tonne
Hz hertz tpa metric tonne per year
in. inch tpd metric tonne per day
in2 square inch US$ United States dollar
J joule USg United States gallon
k kilo (thousand) USgpm US gallon per minute
kcal kilocalorie V volt
kg kilogram W watt
km kilometre wmt wet metric tonne
km2 square kilometre wt% weight percent
km/h kilometre per hour yd3 cubic yard
kPa kilopascal yr year

 

 

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3.0 Property Description

 

3.1 Location

 

El Porvenir’s coordinates are 10°36’36” S, 76°12’37” W (Latitude/Longitude decimals -10.6100, -76.2102). The Mine is located in Peru’s Central Andes region at an elevation of approximately 4,200 MASL. The Mine is situated in the districts of San Francisco de Asís de Yarusyacán and Yanacancha, in the province and department of Pasco. El Porvenir is located 13 km from the city of Cerro de Pasco, which is located approximately 315 km by road from the national capital, Lima, when travelling by the Carretera Central and the La Oroya-Huánuco highway. Figure 3-1 shows El Porvenir’s location in the province of Pasco.

 

3.2 Land Tenure

 

Nexa holds a total of 80.16% that corresponds to the sum of Nexa’s direct interest in Nexa Peru (0.17%) and indirect participation of Nexa in Nexa Peru and Pampa de Cobre S.A.C. (80.06%) through its controlled company Nexa Resources Cajamarquilla S.A. (99.91%), and the remaining 19.76% are floating shares. As of December 31, 2020, the concessions are held in the name of Nexa Resources El Porvenir S.A.C. (Nexa El Porvenir), Nexa Resources Atacocha S.A.A. (Nexa Atacocha), Nexa Peru, and S.M.R.L. CMA No. 54 (50% Nexa El Porvenir and Nexa Atacocha).

 

El Porvenir’s mineral rights consist of 25 mining concessions covering an area of 4,846.77 ha and one beneficiation concession. The relevant mineral rights information, including the code number and concession name, titleholder, status, date, public registry record, and available area for each of the mineral concessions, can be found in Table 3-1 and is shown in Figure 3-2 (Nexa, 2020a). None of these concessions are in urban expansion areas, protected natural areas, or archaeological sites.

 

 

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Table 3-1: El Porvenir Mining Concessions

Nexa Resources S.A. – El Porvenir Mine

 

No.   Code   Concession   Titleholder   Status   Date   Public Registry
Record
  Area
(ha)
1   010000515L   Acumulación El Porvenir   Nexa Resources El Porvenir S.A.C.   Acumulación D.M. Titulada   03/04/1877   P-11248335   4,600.52
2   010000116L   Acumulación El Porvenir 1   Nexa Resources El Porvenir S.A.C.   Acumulación D.M. Titulada   25/01/2016   P-11242512   7.99
3   04013393X01   Carlitos   Nexa Resources El Porvenir S.A.C.   D. M. Titulado D.L. 109   04/05/1987   P-20002989   20.00
4   04013362X0 1   Pucayacu   Nexa Resources El Porvenir S.A.C.   D. M. Titulado D.L. 109   17/06/1986   P-20002923   36.00
5   04005441X01   Angelica Segunda   Nexa Resources Atacocha S.A.A.   D. M. Titulado D.L. 109   06/11/1915   P-0 2005830   2.00
6   04010070X01   Atacocha No. 1   Nexa Resources Atacocha S.A.A.   D. M. Titulado D.L. 109   09/11/1954   P-20000404   1.60
7   04010249X01   Atacocha No. 2   Nexa Resources Atacocha S.A.A.   D. M. Titulado D.L. 109   09/12/1955   P-0 2014333   2.77
8   040 10074X0 1   C.M.A. No. 41   Nexa Resources Atacocha S.A.A.   D. M. Titulado D.L. 109   13/11/1954   P-0 2013928   65.91
9   04010073X01   C.M.A. No. 42   Nexa Resources Atacocha S.A.A.   D. M. Titulado D.L. 109   11/11/1954   P-0 2013917   3.00
10   04010071X01   C.M.A. No. 43   Nexa Resources Atacocha S.A.A.   D. M. Titulado D.L. 109   10/11/1954   P-0 2010565   4.99
11   04010072X01   C.M.A. No. 44   Nexa Resources Atacocha S.A.A.   D. M. Titulado D.L. 109   11/11/1954   P-0 2013919   7.99
12   04010063X02   C.M.A. No. 45   Nexa Resources Atacocha S.A.A.   D. M. Titulado D.L. 109   13/11/1954   P-0 2014009   23.97
13   04010149X01   C.M.A. No. 55   Nexa Resources Atacocha S.A.A.   D. M. Titulado D.L. 109   04/06/1955   P-0 2016190   1.00
14   04005426X0 1   Ithaca   Nexa Resources Atacocha S.A.A.   D. M. Titulado D.L. 109   07/10/1915   P-0 2010173   3 .99
15   040024 71X01   Kathleen   Nexa Resources Atacocha S.A.A.   D. M. Titulado D.L. 109   03/06/1905   P-0 20105 53   5.99
16   0400273 1X01   Kitty   Nexa Resources Atacocha S.A.A.   D. M. Titulado D.L. 109   24/02/1906   P-0 2010298   5.99
17   040053 56X01   La Tunda   Nexa Resources Atacocha S.A.A.   D. M. Titulado D.L. 109   28/10/1935   P-0 2010176   5.99
18   0400 5383X0 1   Manuel Numero Dos   Nexa Resources Atacocha S.A.A.   D. M. Titulado D.L. 109   19/06/1915   P-0 2005462   7.99
19   0400 5372X0 1   Melbourne   Nexa Resources Atacocha S.A.A.   D. M. Titulado D.L. 109   27/05/1915   P-0 2010281   11.98
20   04005505X01   Tralee   Nexa Resources Atacocha S.A.A.   D. M. Titulado D.L. 109   23/02/1916   P-0 2010297   2.00

 

 

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No.   Code   Concession   Titleholder   Status   Date   Public Registry
Record
  Area
(ha)
21   04012874X0 1   C.M.A. No. 95   Nexa Resources Atacocha S.A.A. / Nexa Resources Peru S.A.A.   D. M. Titulado D.L. 109   07/12/1978   P-20000331   3.96
22   04012875X01   C.M.A. No. 96   Nexa Resources Atacocha S.A.A. / Nexa Resources Peru S.A.A.   D. M. Titulado D.L. 109   07/12/1978   P-20000332   3.99
23   010079393   Macapata   Nexa Resources Peru S.A.A.   D. M. Titulado D.L. 708   27/05/1993   P- 200048 29   14.17
24   04010148X0 1   C.M.A. No. 54   S.M.R.L. CMA No. 54   D. M. Titulado D.L. 109   04/06/1955   P- 11105479   2.00
25   04012134 X01   Demasi A AM-No. 1   S.M.R.L. CMA No. 54   D. M. Titulado D.L. 109   13/03/1973   P-20001500   1.00

 

 

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Figure 3-1: Mine Location

 

 

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Figure 3-2: Land Tenure

 

 

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According to the files of the titles granted by the Peruvian Institute of Geology, Mining and Metallurgy (INGEMMET), mineral rights “Acumulación El Porvenir”, “C.M.A. No. 44”, “C.M.A. No. 45”, “Carlitos”, and “Pucayacu” overlap roads, rivers, and a power transmission line. If any such infrastructure or water bodies are affected by exploration or mining activities, Nexa will need to obtain the relevant approvals prior to undertaking any activities.

 

3.2.1 Mineral Rights

 

According to Peruvian General Mining Law (the Law):

 

a. Mineral concessions grant their holder the right to explore, develop, and mine metallic or non-metallic minerals located within their internal boundaries.

 

b. A mineral claim is an application to obtain a mineral concession. Exploration, development, and exploitation rights are obtained once the title to the concession has been granted, except in those areas that overlap with priority claims or priority mining concessions. Upon completion of the title procedure, resolutions awarding title must be recorded with the Public Registry to create enforceability against third parties and the Peruvian State.

 

c. The beneficiation concession grants the right to use physical, chemical, and physical-chemical processes to concentrate minerals or purify, smelt, or refine metals.

 

d. Mineral rights are separate from surface rights. They are freely transferable.

 

e. A mineral concession by itself does not authorize the titleholder to carry out exploration or exploitation activities, but rather the titleholder must first:

 

(i) Obtain approval from the Culture Ministry of the applicable archaeological declarations, authorizations, or certificates.

 

(ii) Obtain the environmental certification issued by the competent environmental authority, subject to the rules of public participation.

 

(iii) Obtain permission for the use of land (i.e., obtain surface rights) by agreement with the owner of the land or the completion of the administrative easement procedure, in accordance with the applicable regulation.

 

(iv) Obtain the applicable governmental licences, permits, and authorizations, according to the nature and location of the activities to be undertaken.

 

(v) Carry out consultations with Indigenous Peoples under the Culture Ministry, should there be any communities affected by potential exploitation of the mineral concession, as per International Labour Organization (ILO) Convention 169.

 

f. Mineral rights holders must comply with the payment of an annual fee equal to $3.00/ha, on or before June 30 of each year.

 

g. Holders of mineral concessions must meet a Minimum Annual Production Target or a Minimum Annual Investment before a statutory deadline. When such deadline is not met, a penalty must be paid as described below:

 

(i) Mineral concessions must meet a statutory Minimum Annual Production Target of 1 Tax Unit (Unidad Impositiva Tributaria, or UIT) per hectare per year for metallic concessions, within a statutory term of ten years from the title date. The applicable penalty is 2% of the Minimum Annual Production Target per hectare per year as of the 11th year until the 15th year. Starting in the 16th year and until the 20th year, the applicable penalty is 5% of the Minimum Annual Production Target per year and starting in the 21st year until the 30th year, the applicable penalty is 10% of the Minimum Annual Production Target per year. After the 30th year, if the Minimum Annual Production Target is not met, the mining concession will lapse automatically.

 

 

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h. Mineral concessions may not be revoked as long as the titleholder complies with the Good Standing Obligations according to which mineral concessions will lapse automatically if any of the following events take place:

 

(i) The annual fee is not paid for two consecutive years.

 

(ii) The applicable penalty is not paid for two consecutive years.

 

(iii) A concession expires if it does not reach the minimum production in Year 30 and cannot justify the non-compliance up to five additional years due to reasons of force majeure described in the current legislation.

 

i. Agreements involving mineral rights (such as an option to acquire a mining lease or the transfer of a mineral concession) must be formalized through a deed issued by a public notary and must be recorded with the Public Registry to create enforceability against third parties and the Peruvian State.

 

3.2.2 Annual Fees and Penalties

 

Pursuant to Table 3-1, all annual fees applicable to the 25 mineral concessions and the beneficiation concession comprising the Mine have been paid in full up to 2020, as detailed in Table 3-2.

 

Certain mineral concessions comprising the Mine were subject to a penalty since the minimum required levels of production or exploration expenditures were not met as stated in the previous subsection (Mineral Rights). The minimum annual production is equal to a UIT per granted hectare. The minimum annual investment is the penalty to be paid multiplied by 10. All penalties applicable to the mineral concessions comprising the Mine, have been paid as indicated in Table 3-2. Penalties were incurred for concessions numbered 6 through 25 for not achieving the required production or exploration expenditures, while concessions 1 through 5 were not subject to penalties as the required annual production levels were met. The penalty amounts shown in Table 3-2 for concessions 1 through 5 represent the annual amounts that would be payable if the Minimum Annual Production Target was not met.

 

Table 3-2:  Payments Made for Concessions in 2020

Nexa Resources S.A. – El Porvenir Mine

 

No.   Code   Concession   Annual Fee
(US$)
  Penalty
(US$)
  Total Payment
2020
(US$)
1   04010070X01   Atacocha No. 1   4.79   38.98   4.79
2   010000515L   Acumulacion El Porvenir   13,801.55   112,338.19   13,801.55
3   010 00011 6L   Acumulacion El Porvenir 1   23.96   194.99   23.96
4   04010149X01   C.M.A. No. 55   3.00   24.39   3.00

 

 

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No.   Code   Concession   Annual Fee
(US$)
  Penalty
(US$)
  Total Payment
2020
(US$)
5   04002731X01   Kitty   17.98   146.32   17.98
6   04010148X01   C.M.A. No. 54   5.99   79.88   85.87
7   04012134X01   Demasia AM-No. 1   3.00   39.94   42.94
8   04005426X01   Ithaca   11.98   159.80   171.78
9   04002471X01   Kathleen   17.98   239.68   257.66
10   04005356X01   La Tunda   17.98   239.68   257.66
11   04005372 X01   Melbourne   35.95   479.38   515.33
12   04005505X01   Tralee   5.99   79.90   85.89
13   04005441X01   Angelica Segunda   5.99   48.77   54.76
14   04010249X01   Atacocha No. 2   8.30   67.52   75.82
15   04010074X01   C.M.A. No. 41   197.72   1,609.33   1,807.05
16   04010073X01   C.M.A. No. 42   8.99   73.15   82.14
17   04010071X01   C.M.A. No. 43   14.98   121.93   136.91
18   04010072X01   C.M.A. No. 44   23.97   195.07   219. 04
1 9   04010063X0 2   C.M.A. No. 45   71.90   585.22   6 57.12
20   04012874X01   C.M.A. No. 95   11.89   96.76   108.65
21   04012875X01   C.M. A. No. 96   11.98   97.53   109.51
22   04013393X0l   Carlitos   60.00   48.84   108.84
23   010079393   Macapata   42.23   343.77   386.00
24   04005383X01   Manuel Numero Dos   23.97   195.10   219.07
25   040 13362X01   Pucayacu   108.00   87.91   195.91
26   P000000613   Acumulacion Aquiles 101
(Beneficiation Concession)
  4,587.50   N/A   4,587.50

 

Note. Exchange rate of 3.44 Peruvian Neuvo Sol (PEN or S/.)/ USD based on SUNAT Exchange Rate as of May 29, 2020.

 

3.3 Royalties

 

According to a lease agreement signed on January 2, 2006, the concessions listed in Table 3-3 are subject to the royalties presented in Table 3-4.

 

 

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Table 3-3:  Concessions Subject to Royalties Payable to Nexa Resources Atacocha

Nexa Resources S.A. – El Porvenir Mine

 

  Angelina Segunda C.M.A. No. 44
  Atacocha No. 1 C.M.A. No. 45
  Atacocha No. 2 Ithaca
  C.M.A. No. 41 Kathleen
  C.M.A. No. 42 Manuel Numero Dos
  C.M.A. No. 43 Melbourne
  C.M.A. No. 55 La Tunda
  Kitty Tralee
     
50% of the Amount Indicated in the Royalty Schedule
  C.M.A. No. 95 C.M.A. No. 96
  Demasia AM No. 1 CMA No. 54

 

Source: Nexa, 2020a

 

Table 3-4: Royalty Payments to Nexa Resources Atacocha

Nexa Resources S.A. – El Porvenir Mine

 

Percentage   Mineral Value Range
7%   Up to US$40/t of mineral value
8%   Above US$40/t and up to US$50/t of mineral value
10%   Above US$50/t and up to US$60/t of mineral value
12%   Above US$60/t and up to US$70/t of mineral value
13%   Above US$70/t and up to US$80/t of mineral value
15%   Above US$80/t and up to US$100/t of mineral value
18%   Above US$100/t of mineral value

 

3.4 Surface Rights and Easements

 

El Porvenir has the following surface rights:

 

On June 30, 1988, Nexa obtained the free right of use of 450.66 ha for the mine site from the Peruvian State.

 

On August 5, 1991, the Ministry of Energy and Mines expropriated 18 ha from the Peasant Community of San Francisco de Asís de Yarusyacán and granted Nexa its surface-property rights for the tailings deposit and other facilities.

 

On February 27, 2012, Nexa purchased six properties totalling 128 ha from the Peasant Community of San Francisco de Asís de Yarusyacán for expanding the tailings deposit, developing an access road, and installing a 138 kV power transmission line. One of the properties (1.05 ha) has not been registered in the Public Registry pending validation of its boundaries. On January 21, 2014, the Peasant Community of San Francisco de Asís de Yarusyacán filed a civil suit against Nexa to cancel the sale of the 128 ha. On November 20, 2016, the community filed another lawsuit against Nexa regarding the same property to void the sales agreement, pay them S/. 1,000,000 for damages, and return the properties. Nexa achieved favourable interim rulings on the first claim.

 

 

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On December 19, 2012, Nexa El Porvenir obtained an easement of 105,458.50 m2 for 30 years from the Peasant Community of San Antonio de Rancas to install, operate, and maintain ten high voltage towers and other related facilities for a 200 kV power transmission line.

 

On December 20, 2012, Nexa El Porvenir obtained an easement of 94,801.7919 m2 for 30 years from Cooperativa Agraria de Producción Pucayacu Número 004 – Yanacancha to install, operate, and maintain ten high voltage towers and other related facilities for a 200 kV power transmission line.

 

On July 24, 2014, Nexa transferred the La Candelaria Power Station and related infrastructure to Nexa El Porvenir. Nexa believes that Nexa El Porvenir has the right to claim property rights over this land through the acquisitive prescription of domain, as it has been in possession of it as an owner for more than ten years.

 

Other surface rights include Predio Carmen Chico and surface rights purchased from the Colqui family.

 

Figure 3-3 illustrates Nexa’s surface rights.

 

 

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Figure 3-3: Surface Rights

 

 

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3.5 Material Government Consents

 

This subsection details the material Governmental Consents required to carry out the operation in compliance with applicable Peruvian laws and regulations. These material Governmental Consents correspond to those permits, licences, authorizations, etc., issued by the applicable governmental authorities, which entitle Nexa Peru to build the components and/or perform the activities that are critical and typical to a mining operation. These components/activities may include: (i) mining activities and related facilities; (ii) beneficiation plant and related activities; (iii) water supply; (iv) effluent discharge and related facilities; (v) use of explosives; and (vi) power supply (Table 3-5). Of note, the third amendment to the Mine Closure Plan is currently under review and approval process by the Peruvian Authorities.

 

Table 3-5: Main Government Consents

Nexa Resources S.A. – El Porvenir Mine

 

#   Government Consent   Resolution   Approval Date
Environmental Certification
1   Adaptation and Environmental Management Program approval.   RD 23-97-EM/DGM   17/01/1997
2   Modification of the Adaptation and Environmental Management Program – Candelaria Power Station.   RD 28-1997-EM/DGM   23/01/1997
3   El Porvenir Environmental Impact Assessment (EIA).   RD 379-2001-EM/DGAA   26/11/2001
4   First amendment to El Porvenir EIA (expansion of processing capacity to 5,500 tpd).   RD 271-2011-MEM/AAM   02/09/2011
5   Second amendment to El Porvenir EIA (expansion of processing capacity to 7,500 tpd).   RD 203-2012-MEM/AAM   25/06/2012
6   EIA for the power supply components (transmission power line).   RD 110-2013-MEM/AAM   17/04/2013
7   Supporting Technical Report to Directorial Resolution 110-2013- MEM/AAM (optimization of the design of the power transmission line).   RD 159-2014-MEM/DGAAM   02/04/2014
8   Supporting Technical Report to Directorial Resolution 203-2012- MEM/AAM (integrate the tailings disposal from the Atacocha and El Porvenir operations).   RD 526-2014-MEM-DGAAM   20/10/2014
9   Supporting Technical Report to Directorial Resolution 110-2013- MEM/AAM (optimization of the design of the power transmission line).   RD 271-2015-MEM-DGAAM   09/07/2015
10   Supporting Technical Report for expansion of processing capacity to 9,000 tpd.   RD 319-2017-SENACE-DCA   24/10/2017
11   Supporting Technical Report for modifications of ancillary components.   RD 058-2018-SENACE- PE/DEAR   13/12/2018
12   Supporting Technical Report for modification of the 9,000 tpd expansion and tailings pipe connection to Atacocha.   RD 051-2020-SENACE-PE/DEAR   10/03/2020

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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#   Government Consent   Resolution   Approval Date
Mine Closure Plan
1   El Porvenir Mine Closure Plan.   RD 166-2009-MEM/AAM   17/06/2009
2   First Amendment to the Mine Closure Plan.   RD 286-2011-MEM/AAM   15/09/2011
3   Updated Mine Closure Plan.   RD 034-2013-MEM/AAM   30/01/2013
4   Second Amendment to the Mine Closure Plan.   RD 277-2016-MEM-DGAAM   15/09/2016
Beneficiation Plant and Tailings Storage Facilities (TSF)
1   Beneficiation Concession Title.   RD 1058-1965   31/12/1965
2   Authorization to operate the beneficiation plant with 2,000 tpd Capacity.   RD 180-79-EM/DCFM   01/10/1979
3   Beneficiation Concession Titles “AQUILES 104” (tailings disposal over 18 ha).   RD 280-97-EM/DGM   12/08/1997
4   Beneficiation Concession Titles “AQUILES 103” (tailings disposal over 48 ha).   RD 281-97-EM/DGM   12/09/1997
5   Authorization to operate the beneficiation plant at 2,850 tpd.   RD S/N-99-EM-DGM/DPDM   03/03/1999
6   Authorization to operate the beneficiation plant at 4,000 tpd.   Auto Directorial AD 113-2004-MEM-DGM/DPM   08/03/2004
7   Authorization to operate the tailing deposit “El Porvenir” to a height of 4,043 MASL   RD 178-2010-MEM   07/04/2010
8   Authorization to operate the beneficiation plant at 4,700 tpd.   RD 206-2011-MEM-DGM/V   23/06/2011
9   Authorization to operate additional components for the beneficiation plant without extending the processing capacity.   RD 37-2012-MEM-DGM/V   18/01/2012
10   Authorization to operate the beneficiation plant at 5,600 tpd.   RD 235-2013-MEM-DGM/V   30/05/2013
11   Beneficiation concession “ACUMULACION AQUILES 101” (gather beneficiations concessions “AQUILES 104” and “AQUILES 103”).   RD 178-2013-MEM/DGM   04/07/2013
12   Authorization to construct the tailing deposit “El Porvenir” to a height of 4,115 MASL.   RD 429-2013-MEM-DGM/V   15/11/2013
13   Authorization to operate the tailings deposit “El Porvenir” at a height of 4,047 MASL and extend the area of such beneficiation concession to a total of 323.7932.   RD 612-2015-MEM/DGM   12/06/2015
14   Authorization to operate additional components that integrate the tailings disposals from Atacocha and El Porvenir operations.   RD 251-2015-MEM-DGM/V   19/06/2015
15   Authorization to operate the beneficiation plant at 6,700 tpd.   RD 597-2015-MEM-DGM/V   03/12/2015

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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#   Government Consent   Resolution   Approval Date
16   Authorization to operate additional components for the beneficiation plant without extending the processing capacity.   RD 635-2015-MEM-DGM/V   12/12/2015
17   Authorization to operate the tailings deposit “El Porvenir” to a height of 4,048.5 MASL.   RD 0499-2016-MEM-DGM/V   18/08/2016
18   Authorization to operate the tailings deposit “El Porvenir” to a height of 4,056 MASL.   RD 828-2017-MEM-DGM/V   25/09/2017
19   Authorization to increase the tailings deposit “El Porvenir” to a height of 4,060 MASL.   RD 0498-2019-MINEM-DGM/V   07/10/2019
Water Abstraction, Transportation and Usage Facilities
1   License to use surface water from Huarmipuquio, Quebrada Pucayacu for population purposes.   RD 264-2015-ANA-AAA-X-MANTARO   06/04/2015
2   License to use surface water from the rivers “Lloclla”, “Yanacachi”, “Chuncana”, and “Tulluraica” for power supply purposes.   RD 86-2016-ANA/AAA-HUALLAGA   11/02/2016
3   Licence to use surface water from the ravines. “Pucayacu – Huarmipuquio” and “Pucayacu – Carmen Chico” for mining purposes.
  RD 399-2016-ANA/AAA-HUALLAGA   13/06/2016
4   Authorization to reuse treated domestic effluents from the camp of the operation for mining purposes.   RD 600-2019-ANA/AAAHUALLAGA   06/07/2019
5   Update to the Licence to use surface water from the ravines “Pucayacu – Huarmipuquio” and “Pucayacu – Carmen Chico” for mining purposes due to titleholder name change.   RA 322-2019-ANA/AAA-HUALLAGA-ALA ALTO HUALLAGA   03/10/2019
Effluent Discharge to the Environment
1   Authorization to discharge treated industrial effluents to rivers “Huallaga” and “Lloclla”.   RD 192-2019-ANA-DGCRH   16/06/2019
Power Generation and Transmission Lines
1   Authorization to generate electricity for 1,936 kW in the hydroelectric plant “Candelaria”.   Ministerial Resolution RM 395-93-EM/DGE   31/12/1993
2   Authorization to auto-generate electricity in the thermoelectric plant “Milpo”.   Ministerial Resolution RM 394-93-EM/DGE   31/12/1993
3   Authorization to generate electricity for 3,187.50 kW in the hydroelectric plant “Candelaria”.   Ministerial Resolution RM 541-98-MEM/VME   03/11/1998
4   Power transmission concession for the 50 kV Power Transmission Line – Hydroelectric Plant “Candelaria” – S.E. N° 3 at El Porvenir.   Supreme Resolution RS 75-2010-EM   25/11/2010
5   Approve the transfer of the power transmission concession to Nexa El Porvenir.   Supreme Resolution RS 004-2015-EM   06/03/2015

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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#   Government Consent   Resolution   Approval Date
6   Power transmission concession for the 138 kV Power Transmission Line – Paragsha II – S.E. Milpo and 50 kV Power Transmission Line S.E. Milpo – V1C.   Ministerial Resolution RM 361-2016-MEM/DM   31/08/2016
Use of Explosives
1   Authorization to operate an underground magazine – Explosives   RD 304-2020-SUCAMEC/GEPP   05/02/2020
2   Authorization to operate an underground magazine – Accessories   RD 305-2020-SUCAMEC/GEPP   05/02/2020
3   Authorization to operate an underground magazine – Accessories   RD 306-2020-SUCAMEC/GEPP   05/02/2020
4   Authorization to use and acquire explosives for UEA Milpo No. 1   RD 308-2020-SUCAMEC/GEPP   05/02/2020

 

Source: Nexa, 2020a

 

The SLR QP is not aware of any environmental liabilities on the property. Nexa has all required permits to conduct the proposed work on the property. The SLR QP is not aware of any other significant factors and risks that may affect access, title, or the right or ability to perform the proposed work program on the property.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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4.0 Accessibility, Climate, Local Resources, Infrastructure and Physiography

 

4.1 Accessibility

 

El Porvenir is located 13 km northeast of Cerro de Pasco via an unpaved road. Cerro de Pasco is situated approximately 315 km from Lima, the national capital, when travelling via the Carretera Central and La Oroya-Huanuco highways, which are paved roads. Alternatively, Highway 20A provides a shorter drive from Lima but is mostly unpaved. The nearest airport to the Mine is Alférez FAP David Figueroa Fernandini Airport (HUU which is located approximately 130 km to the north of El Porvenir, just outside of Huanuco. Two regional airlines provide daily flights between the airport and Lima.

 

4.2 Climate

 

The climate at El Porvenir is cold and humid and is generally typical of the Central Andes Mountain Region, where elevations exceed 4,000 MASL. The temperature is relatively uniform throughout the year averaging approximately 6°C and ranging from -4°C to +13°C. Precipitation in the region totals approximately 1,000 mm annually, mainly falling during the rainy season from November to March, conversely the months of June and July are mostly dry. Snowfall occurs at any time of the year, most commonly at dawn. Relative humidity is relatively uniform throughout the year averaging 78%. Mining operations are not affected by the climate and are carried out year-round.

 

4.3 Local Resources

 

The El Porvenir site is situated adjacent to the small municipality of San Juan de Milpo. The nearest city to the Mine is Cerro de Pasco, which has a population of approximately 60,000. Huanuco has a population of approximately 190,000. Most supplies used in the mining operation are delivered by truck from Lima.

 

4.4 Infrastructure

 

The El Porvenir infrastructure consists of the following facilities:

 

Approximately 6,000 tpd underground mine

A 2.2 million tonnes per annum (Mtpa) processing plant with associated laboratory and maintenance facilities

Power plant

Access roads

Offices and warehouses

Accommodations

Waste rock facilities

Temporary ore stockpiles

Hydraulic backfill plant

TSF

 

Additional information on infrastructure is provided in Sections 15 and 17.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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4.5 Physiography

 

El Porvenir is situated in a glacial valley flanked by mountains on each side (Figure 4-1). The Mine’s TSF, processing plant, and other buildings are located at the valley’s base. A creek running through the valley drains into the Huallaga River further downstream at the village of La Quinua. The physiography of the area is typical of the Central Andes Mountain Region.

 

 

 

Source: SRK, 2017

 

Figure 4-1: Typical Landscape at El Porvenir

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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5.0 History

 

5.1 Ownership, Exploration and Development History

 

El Porvenir has a long history in the Peruvian mining sector, extending over 70 years. The Mine began operating as a small scale artisanal mine in 1949, and Compañía Minera Milpo S.A. (Milpo) was incorporated the same year to operate the Mine. A gravity separation plant was built at the site in 1953, and a flotation plant was completed in 1979. The Mine’s output increased steadily over the decades, attaining its current production rate of 5,600 tpd in 2014.

 

No documentation on exploration is available prior to 2006. Exploration was conducted simultaneously with underground development and included geological mapping, diamond core drilling, and channel sampling (SRK, 2017). Milpo acquired the adjacent Atacocha Mine in 2008. In 2010, Nexa, then Grupo Votorantim (Votorantim), gained control of Milpo and its assets, including El Porvenir. In 2014, Nexa began integrating the El Porvenir and Atacocha operations, including administration, the TSFs, and the electrical power supply. El Porvenir’s operations were recently interrupted from March 10, 2020 to May 15, 2020, due to the COVID-19 pandemic.

 

Table 5-1 lists chronologically the most significant events in the operation’s history.

 

Table 5-1: History of the El Porvenir Mine 

Nexa Resources S.A. – El Porvenir Mine

 

Year   Work Description
1939   The El Porvenir site is granted June 30, 1939 through Resolución Jefatural
N° 076-88-EM-DGM/JRMCP.
1949   El Porvenir began operating as a small scale artisanal mine.
Milpo was incorporated on April 6, 1949, by founders Mr. Aquiles Venegas, Mr. Amador Nycander, Mr. Ernesto Baertl, Mr. Manuel Montori, and Mr. Luis Cáceres P.
1953   Milpo built a gravity separation plant, which had a capacity 54,000 t/month.
The plant was expanded several times until 1978.
1979   Construction of the flotation plant was completed, capacity 1,800 tpd.
1997   A new mineralized zone called Porvenir Nueve was discovered.
1999   Production increased to 3,000 tpd.
2008   Milpo acquired the Atacocha Mine.
2010   Votorantim (now Nexa) gained control of Milpo and its assets, including El Porvenir.
2012   El Porvenir’s production increased to 5,600 tpd.
2013   Votorantim initiated the process of integrating the Atacocha and El Porvenir mines, forming the Cerro Pasco Mining Complex.
2014   The 1st stage integration was initiated, which consisted of integrating the administrative functions of the two operations.
2015   The 2nd stage integration was initiated, which consisted of integrating TSFs of Atacocha and El Porvenir.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Year   Work Description
2016   The 3rd stage integration was initiated, which consisted of integrating the electric power supply of the two mines.
2017   Votorantim changed its name to Nexa.
The integration process continued:

The two underground mines were connected by a drift allowing an exploration program to proceed in the integration area.
2018   Nexa implemented the Avoca version of the sublevel stoping (SLS) mining method at El Porvenir.
Discovery of the Sara Deposit, in which the mineralization occurs in sandstone.
2019   The tailings dam level was increased to the 4,060 MASL elevation, which extended it useful life by an additional five years.
The Avoca/SLS mining method contributed to 6% of El Porvenir’s total production.
Nexa initiated a program called the Nexa Way Experience (La Manera Nexa Experience) aiming to optimize organizational performance through autonomous work groups and employee self-management.
2020   The Nexa Way Experience program continued and, at El Porvenir, focused on lowering costs by reducing shotcrete consumption.
El Porvenir’s operations were halted from March 18 to May 15 due to the COVID-19 pandemic.
Operations were reinitiated with the application procedures and sanitary controls to prevent the spread of the contagion.

 

5.2 Past Production

 

Table 5-2 presents El Porvenir’s annual mine production since the beginning of operations. Table 5-3 provides information about the operation’s yearly concentrate production from 2016 to 2020.

 

Table 5-2:  Mine Production History

Nexa Resources S.A. – El Porvenir Mine

 

    Grade       Grade
Year    Dry Tonnes (t)   (oz/t Ag)   (% Pb)   (% Zn)   Year    Dry Tonnes (t)   (oz/t Ag)   (% Pb)   (% Zn)
1950   5,144   15.90   10.30   13.60   1985   661,298   4.40   3.20   5.60
1951   13,068   12.10   8.20   11.10   1986   640,133   4.30   3.20   5.50
1952   27,478   10.90   7.10   9.20   1987   597,611   4.20   3.10   4.80
1953   33,220   7.60   6.10   7.90   1988   472,414   4.30   3.10   4.80
1954   52,747   8.10   6.50   7.50   1989   679,647   4.50   3.60   4.60
1955   72,662   7.90   6.10   7.30   1990   763,860   4.50   3.40   5.30
1956   101,172   6.90   6.10   7.50   1991   788,234   4.10   2.80   5.50
1957   118,167   6.90   6.40   6.90   1992   747,455   3.80   2.80   5.30
1958   122,740   6.40   6.20   6.40   1993   776,051   4.00   3.20   5.70
1959   135,005   5.90   6.30   6.50   1994   781,893   3.90   3.00   5.60
1960   157,174   6.60   6.10   6.70   1995   784,090   4.30   3.50   5.70

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

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    Grade       Grade
Year    Dry Tonnes (t)   (oz/t Ag)   (% Pb)   (% Zn)   Year   Dry Tonnes (t)   (oz/t Ag)   (% Pb)   (% Zn)
1961   178,360   5.90   5.70   7.00   1996   874,890   3.80   2.70   6.20
1962   180,577   5.30   5.60   6.20   1997   968,023   3.70   2.40   6.70
1963   176,475   5.20   5.70   6.50   1998   938,549   3.09   2.23   6.62
1964   186,642   5.00   5.10   5.70   1999   1,010,627   3.40   2.50   7.40
1965   181,240   5.30   5.10   6.00   2000   1,049,857   3.30   2.10   7.30
1966   204,800   5.50   5.20   5.60   2001   1,067,890   3.35   2.33   7.70
1967   224,656   5.30   5.40   5.80   2002   1,217,291   3.65   2.58   8.02
1968   244,647   4.80   5.20   6.20   2003   1,313,346   3.51   2.45   7.69
1969   265,264   4.70   4.80   6.20   2004   1,342,451   2.21   1.41   7.61
1970   268,048   4.70   4.70   6.70   2005   1,395,991   2.44   1.64   6.87
1971   274,516   4.90   4.90   6.90   2006   1,390,940   2.51   1.68   6.10
1972   280,265   4.40   4.50   6.60   2007   1,333,313   1.90   1.19   5.31
1973   307,683   4.30   4.30   6.50   2008   1,389,947   1.60   0.88   4.23
1974   312,529   4.40   4.20   6.70   2009   1,712,188   1.30   0.68   4.07
1975   278,680   4.10   3.80   6.40   2010   1,712,188   1.23   0.60   4.04
1976   309,518   4.20   3.70   6.50   2011   1,742,129   1.23   0.54   4.00
1977   296,578   4.00   3.20   7.00   2012   1,898,901   1.13   0.48   4.04
1978   336,790   4.40   3.00   7.40   2013   1,943,490   1.37   0.82   3.48
1979   389,830   4.30   3.20   7.20   2014   2,107,212   1.49   0.88   3.39
1980   444,230   4.20   3.00   6.50   2015   2,106,519   1.75   0.93   3.21
1981   470,735   3.90   2.60   5.70   2016   2,154,152   1.94   0.98   3.22
1982   521,859   4.30   2.90   5.60   2017   1,834,511   2.05   1.04   2.86
1983   633,861   4.50   3.10   5.60   2018   2,149,928   1.92   0.98   3.04
1984   574,354   4.40   3.10   6.00   2019   2,120,765   2.08   1.01   2.92
                    2020   1,502,618   2.00   0.93   2.65

 

Source: Nexa, 2020

 

 

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Table 5-3: Concentrate Production – 2016 to 2020

Nexa Resources S.A. – El Porvenir Mine

 

    2016   2017   2018   2019   2020
Treatment Ore (in tonnes)   2,154,151   1,834,511   2,149,927   2,120,765   1,502,618
Average Ore Grade                    
Zinc (%)   3.22   2.86   3.04   2.92   2.65
Copper (%)   0.14   0.13   0.15   0.15   0.17
Lead (%)   0.99   1.04   0.98   1.01   0.93
Silver (ounces per tonne)   2.01   2.05   1.92   2.08   2.00
Metal Contained in Concentrate Production                    
Zinc (in tonnes)   62,534   46,154   57,872   54,689   34,867
Copper (in tonnes)   653   493   567   465   334
Lead (in tonnes)   17,164   14,818   16,641   16,914   10,858
Silver (in oz)   2,715,143   2,357,442   2,533,801   3,412,656   2,315,000

 

Source: SEC Form 20-Fs for 2019 and 2018 and Nexa 2020

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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  (GRAPHIC)

 

 

6.0 Geological Setting, Mineralization, and Deposit

 

6.1 Regional Geology

 

The South American Platform is mainly composed of metamorphic and igneous complexes from the Archean/Proterozoic era and constitutes the continental interior of South America. The Platform was consolidated during late Proterozoic to early Paleozoic times in the course of the Brasilian/Pan-African orogenic cycle during which the union of different continents and micro-continents with the closure of several ocean basins led to the formation of the supercontinent Gondwana. Archaean and Proterozoic rocks are exposed in three main shield areas within the framework of the Neoproterozoic folding strips (Guiana, Central Brazil, and Atlantic Shields). The western continental margin of the South American Plate developed from approximately Neoproterozoic to early Paleozoic times and constitutes a convergent margin, along which the eastward subduction of the Pacific oceanic plates takes place under the South American plate. Through this process, the Andean Range was developed. The eastern margin of the South American Plate forms a divergent margin more than 10,000 km long, which developed as a result of the separation of the South American Plate and the African Plate from the Mesozoic through the opening of the South Atlantic and the rupture of Gondwana. The northern and southern margins of the South American Plate developed along transform faults in transient tectonic regimes due to the collision of the South American Plate with the Caribbean and Scottish plates. The South American Plate reveals a long and complex geological history (Engler, 2009).

 

Most of the stratigraphy, tectonics, magmatism, volcanism, and mineralization in Peru is spatially and genetically related to the evolution of the Andean Cordillera off the western coast of South America. The mountain range was formed by actions related to important events (for example subduction) that have continued to the present since approximately the Cambrian (Peterson, 1999) or the late Precambrian (Clark et al., 1990; Benavides-Cáceres, 1999). The formation of the Andean Cordillera is, however, the result of a narrower period extending from the Triassic to the present when the division of the African and South American continents formed the Atlantic Ocean. Two periods of this subsequent subduction activity have been identified (Benavides-Cáceres, 1999): Mariana-type subduction from the late Triassic to the late Cretaceous; and Andean-type subduction from the late Cretaceous to the present.

 

The geology of Peru, from the Peru-Chile trench in the Pacific to the Brazilian Shield, is defined as three main parallel regions, from west to east: the Andean Antearco, the high Andes, and the Andean Antepaís Basin. All three regions were formed during the Meso-Cenozoic evolution of the central Andes. The property is located within the high Andes region. A simplified geological map of Peru is shown in Figure 6-1 and a regional morphostructural map is shown in Figure 6-2.

 

The Andes can be divided into three sections, from west to east:

 

The Western Cordillera is formed by rocks of the Mesozoic-Tertiary age, dominated by the coastal batholith, which consists of multiple intrusions with ages ranging from the Lower Jurassic to the Upper Eocene. The belt is up to 65 km long and 1,600 km long and extends in a sub-parallel direction from the Pacific coast to Ecuador and Chile. El Porvenir is located within the Western Cordillera.

 

The Altiplano is a high plain with internal drainage located at an average elevation of almost 4,000 m, slightly below the average altitudes of the Western and Eastern Cordillera. It is 150 km wide and 1,500 km long, stretching from the north of Argentina to the south of Peru.

 

 

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(GRAPHIC)  

 

The Eastern Cordillera forms a plateau 4,000 m high and 150 km wide. During the Cenozoic era, the arch has risen forming the Eastern Cordillera. Stratigraphically, the zone of the high Andes is composed, from west to east, of an intra-arch channel, a deep basin, a continental shelf, and the Marañón metamorphic complex (the Marañón complex). In general, the formations are progressively older from west to east, spanning from the mid-Tertiary to the Neoproterozoic-Paleozoic.

 

 

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(GRAPHIC)  

 

Figure 6-1: Simplified Geological Map of Peru

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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(GRAPHIC)  

 

Figure 6-2:           Morphostructural Map of Peru

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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6.2 Local Geology

 

The following section is abridged from SRK (2017), with updates from Nexa (2020). Figure 6-3 illustrates the local geology.

 

El Porvenir is situated in the Pasco region of the Western Cordillera of the Andes, within the Eocene-Miocene Polymetallic and Miocene Au-Ag Epithermal Belts.

 

6.2.1 Stratigraphy

 

The oldest rocks in the region are part of the Devonian Excelsior Formation, comprising metamorphosed siliciclastic sediments or phyllite and quartzite.

 

The Upper Permian-Middle Triassic Mitu Group comprises clastic and volcanic sediments, including red sandstone, shale, and minor conglomerate. At the base of the Mitu Group there is a polymictic conglomerate unit which is approximately 45 m thick. Conglomerate clasts are subangular, comprising shale, phyllite, quartzite, and minor limestone. The conglomerate matrix is a well cemented, fine grained, reddish sandy material. Thin, grey to reddish siltstone layers are also present, and exhibit laminar stratification. The middle part of the Mitu Group comprises sequences of fine grained, reddish sandstone, with cross-stratification and interbedded with polymictic conglomerate layers. The Mitu Group was deposited during the Late Hercynian Tectonic Phase (based on the fossil record, and radiometric age dating). An angular unconformity exists between the underlying Excelsior Formation and overlying Mitu Group. The sediment package has accumulated with increasing thickness to the east, locally up to approximately 2,000 m, thinning to possibly as little as 100 m thickness in areas.

 

The Norian-Toarcian Pucará Group was deposited in the Pucará Basin, a north-northwest trending trough associated with a transtensional shear zone accommodating rifting and sinistral movement, on the Mitu Group with an erosional and angular unconformity. The Pucará Group is dominated by carbonate platform sequences which were primarily deposited in a shallow water environment during the first marine progression of the Andean Orogenic Cycle from the Upper Triassic to Lower Jurassic. The Pucará comprises interbedded grey to black limestone, dolostone, and shale with varying thicknesses of up to 60 cm, and is sub-divided into three formations: Chambará, Aramachay, and Condorsinga (Megard, 1968).

 

The Norian to Rhaetian Chambará Formation overall comprises massive, grey to pale limestone beds with some layers containing chert nodules, and horizons of grey to beige calcareous siltstone with variable oxides and red shale. Thicknesses vary from approximately 600 m to over 3,000 m. This formation is further sub-divided into stratigraphic units at the project scale.

 

The Hettangian to Sinemurian Aramachay Formation is characterized by dark grey bituminous calcareous shales and limestone beds over 15 cm thick. This formation was deposited in a deeper-water environment.

 

The Sinemurian to Toarcian Condorsinga Formation comprises beige to grey, thin to massive, interbedded limestone and dolostone. The thicknesses vary from approximately 500 m to over 1,500 m.

 

The Hauterivian to Aptian Goyllarisquizga Group, composed of siliciclastic sediments, vary from 150 m to 600 m thick and was deposited during the Lower Cretaceous with an erosional and angular unconformity over the Pucará Group during the Lower Cretaceous. Variable and discontinuous units of conglomerate, chert, and/or shale with carbonaceous fragments occur at the base of this group, which correlates with the Chimú Formation. A sequence of approximately 40 m thick comprising bitumen-bearing siltstone, with carbonaceous layers and laminar stratification is located above the Chimú Formation. Continuing up in the stratigraphic sequence is a section approximately 25 m thick comprising medium grain, reddish sandstone with thin micro-conglomerate layers, alternating with white sandstone further up in the sequence. These sequences correlate with the Santa and Carhuaz formations. The majority of the Goyllarisquizga Group comprises cross-bedded grey to white, medium to coarse grained, quartz-rich sandstone, approximately 90 m thick or more, which correlates with the Farrat Formation. Over one metre thick limestone units are present locally in the upper parts of this formation. Thin terrestrial red beds and basalt layers one to two metres thick may be interbedded near the upper contact.

 

 

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A discontinuous, predominantly basaltic flow occurs in the Goyllarisquizga Group. Thin, red beds of sandstone and shale occur within the basalt unit.

 

The equivalent Machay and Chicrín formations comprise of approximately 250 m of massive to thinly interbedded grey calcareous sandstone, grey to brown marly limestone, grey calcareous conglomerate with clasts of fine to muddy sandstone, and fine grained red sandstone. These rocks were deposited onto the basalt flows during the Middle Cretaceous.

 

Another unit of predominantly basalt flows with thin beds of red sandstone and shale was disconformably deposited on top of the Machay/Chicrín formation.

 

The Upper Eocene Pocobamba Formation comprises breccias with sub-angular to sub-rounded limestone clasts derived from the Pucará Formation; subdivided into the Cacuán and Shuco members. The Pocobamba Formation was deposited as debris in a continental environment.

 

The regional stratigraphic column is shown in Figure 6-4.

 

 

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Figure 6-3:             Local Geology

 

 

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Figure 6-4:        Generalized Stratigraphic Column

 

 

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6.2.2 Intrusive Rocks

 

Two generations of magmatism are recognized in the region, including the Milpo-Atacocha-Vinchos (29-26 Ma) and Cerro de Pasco-Colquijirca (16-10 Ma) belts (Cobeñas, 2008, and references therein). Both magmatic belts are oriented north-northeast to south-southwest, approximately parallel to the Andean trend.

 

The Milpo-Atacocha-Vinchos intrusive rocks are characterized as small hypabyssal stocks (less than one square kilometre), dikes, and sills of granodiorite (dacite) to diorite and tonalite composition and occur within high-K Calc-Alkaline Series and Shoshonitic Series. These intrusive rocks generally exhibit a porphyritic texture with plagioclase as the dominant mineral forming the matrix, and variable phenocrysts of quartz, hornblende, biotite, and pyroxenes. The matrix comprises fine-grained quartz and feldspar-plagioclase.

 

Magmatic emplacement occurred during the Oligocene based on two K-Ar age dates of porphyritic granodioritic samples with partially carbonate and sericite altered plagioclase (29.3±2.5 Ma and 25.9±1.5 Ma) (Soler and Bonhomme, 1988). Recently, 12 intrusive rocks samples from the El Porvenir and Atacocha areas were analyzed by U-Pb geochronology at the University of Tasmania and provided age dates of intrusive crystallization from 28.58 ± 0.38 Ma to 30.11 ± 0.23 Ma.

 

Intrusives in the region exhibit an elongate geometry, trending north-south to northwest-southeast, parallel to the regional fold axis, and are mostly spatially associated with the Milpo-Atacocha fault, suggesting that there is an apparent structural control on magmatic emplacement.

 

Metamorphic contact aureoles are variably formed around these intrusive bodies. The most intense contact aureole is recognized in the Atacocha area, where Pucará Group rocks are completely silicified with pyrite impregnations for up to 200 m.

 

The Cerro de Pasco-Colquijirca volcanic to sub-volcanic intrusive rocks are characterized by dacitic, trachytic, and monzonitic composition. Texture varies from porphyritic to aphanitic. Composition is dominated by quartz and plagioclase, with lesser amphiboles, biotite, and K-feldspar. Age dating from the Cerro de Pasco, Marcapunta, and Yanamate complexes reveals ages ranging from 16 Ma to 10 Ma.

 

6.2.3 Structure

 

Regional tectonics during the Mesozoic and Cenozoic are collectively referred to as the Andean Cycle which comprises multiple sedimentation and deformational events. The Andean Cycle is sub-divided into at least seven deformational phases (Ellison et al., 1989):

 

Peruana (Upper Cretaceous);

 

Incaica (Paleogene/Eocene);

 

Quechua 1 (early Oligocene);

 

Quechua 2 (late Oligocene to early Miocene);

 

Quechua 3 (middle Miocene);

 

Quechua 4 (late Miocene); and

 

Quechua 5 (late Miocene).

 

 

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Three episodes of regional folding are recognized occurring during the Paleogene and possibly earlier and are separated by periods of tension. Throughout the region, the tectonics are characterized by northeast-southwest to east-west oriented compression, which occurred during the second Andean deformation phase (Incaico), from the Eocene to Oligocene. Most Mesozoic rocks appear to have been folded conformably generally forming a series of anticlines and synclines, parallel to the principal Andean trend, with a north-northwest to south-southeast oriented fold-axis, plunging to the south. Most folds described throughout the region have gently to moderately dipping (<60°) limbs. 

 

The Milpo-Atacocha fault is a major structural feature in the region, which can be traced for nearly 15 km from Yarusyacán in the north to Carmen Chico in the south. The Milpo-Atacocha fault strikes north-south, dipping steeply to the east, with as much as 2,000 m of reverse displacement (east-block up) and probable sinistral movement. Megard (1968) considers that the Milpo-Atacocha fault may be part of a fault system active since at least the Triassic, and during the Upper Cretaceous.

 

A series of fracture sets reportedly formed in response to the northeast-southwest tectonic compression, including:

 

1. North-northeast trending dextral faults;

 

2. Southwest trending sinistral faults;

 

3. Northeast trending tensional joints;

 

4. Northwest trending tensional joints.

 

 

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Figure 6-5:         Regional Geological Setting with Major Structural Features

 

 

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6.3 Property Geology

 

This section is based on SRK (2017) and Nexa (2020).

 

The geology of El Porvenir was compiled based on various internal Milpo reports. Figure 6-6 shows two representative geologic cross sections through the El Porvenir area.

 

Within the property area, the stratigraphic units of primary interest are the Pucará and the Goyllarisquizga groups.

 

The Pucará Group is subdivided into six units: A, B, C, D, which correspond to the Chambará Formation; and E and F, which correspond to the Aramachay and Condorsinga formations, respectively:

 

Unit A is located to the east of the Atacocha fault. It consists of a grey to dark grey limestone with thin dolomite layers, calcarenites and fine, greenish volcanic siltstones at the base of the Chambará Formation. Yellowish grey limonites to compact dolomicrites are also observed.

 

Unit B is located to the east of, and stratigraphically above, Unit A. Dark grey to black coloured limestones, dolomicrites, and micrites are observed in thin layers to tabular strata with lenticular bituminous horizons. It can be seen in many parts of the mine due to its obliteration of marble and silicification. The more competent rocks are located at the intermediate zone in the Chambará Formation.

 

Unit C is located to the east of the mine area. Monotonous grey chertic limestones in metric strata are observed. The unit also contains dolomitic horizons. Its lithologic sequences are hard and it represents the intermediate zone of the Chambará Formation.

 

Unit D is widely distributed within the Atacocha and Santa Bárbara sections. The limestones are beige varying from mudstone to grainstone with light beige dolomitic intercalations. Cherts and bituminous horizons are also observed. Unit D corresponds to the upper zone of the Chambará Formation.

 

Unit E consists of black micritic limestones and black lutite. In many places, this package is obliterated by marble, silica, silica-sericite-clay, etc. In many places of the mine, the rock is altered becoming recrystallized and discoloured, adopting clearer tones without converting to marble (loss of calcium). These rocks correspond to the Aramachay Formation of the Pucará Group.

 

Unit F is grey to light grey limestones, mudstone to packstone, with fossil horizons and dolomitic levels.

 

The Goyllarisquizga Group outcrops in the area of the deposit comprising quartz rich sandstone, corresponding to the Goyllarisquizga Formation. Sandstones may vary from quartz arenite to arkose. The matrix is argillaceous to siliceous. Above the 4000 Level, the lithology and stratification are well defined and easy to recognize. Below the 4000 Level, strong alteration has obliterated the original rock intensity forming siliceous breccias and massive silica where it is still possible to recognize quartz grains and in few places the stratification.

 

Localized basalt units are observed in some drill holes to the southwest of the mine, below the Cherchere and San Gerardo zones. The units consist of grey to greenish basalt with green vacuoles of zeolites with traces of flows with olivine phenocrystals, limonite, and magnetite.

 

 

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Intrusive rocks within the property are variably porphyritic dacite to quartz diorite with hornblende and biotite phenocrysts. Dacitic dikes are subdivided into two units: porphyritic with feldspar phenocrysts and minor quartz restricted to the groundmass; and porphyritic with abundant quartz phenocrysts, with minor biotite and hornblende. The quartz diorite comprises feldspar phenocrysts up to 6 mm long, with variable quartz “eyes”, and aggregates of biotite and hornblende. The groundmass is microcrystalline quartz and plagioclase. These intrusive rocks generally form dikes trending north-south and are observed in three areas: Santa Bárbara/central, south along/parallel to the Atacocha fault, and the southern Section 3. These intrusive rocks are part of the Milpo-Atacocha-Vinchos Belt (28 Ma to 30 Ma).

 

 

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Figure 6-6:         Representative Cross Sections through El Porvenir Area

 

 

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6.4 Alteration

 

Skarn-related alteration has been characterized according to dominant key mineral assemblages: silica-wollastonite, garnet, silica, and pyrite-argillic.

 

Garnet-skarn is dominated by >50% garnet (by volume), generally brown to greenish and medium to fine grained, or light brown to yellowish (andradite) and light green (grosularia). Pyroxene, where present, is light green, very fine grained, and associated with minor sulphides. Magnetite is spatially associated with green garnet areas, as well as lesser pyrite and pyrrhotite.

 

Silica-skarn is defined where silica content exceeds 50%. Silica may occur in veinlets or as disseminations. Silica-wollastonite alteration appears to form a sub-division of the silica-dominant group, and forms light grey to milky white zones with brecciated to massive/patchy textures. Wollastonite may form radiating fibrous crystals. Locally, a silica-skarn-chlorite assemblage may be present, exhibiting strong structural controls. White to grey silica developed early, followed by green skarn with variably associated chlorite and hematite.

 

Pyrite-argillic skarn comprises 30% to 80% massive pyrite, with 10% to 30% undistinguished whitish clays, and up to 20% greenish garnet. Locally, pyrite appears to be pseudomorphic replacing garnet.

 

An alteration assemblage comprising silica-sericite-argillic (halloysite, montmorillonite, and kaolinite) is associated with hydrothermal mineralization. Locally this alteration assemblage is strong, and possibly replaces original rocks completely in areas below the 4000 Level.

 

West of the Milpo-Atacocha fault below the 4000 Level, strong siliceous alteration has variably obliterated the original rock; within the Goyllarisquizga Group it is possible to recognize quartz grains and stratification in a few places. Locally siliceous cemented breccias with silica-sericite-clays matrix (halloysite, montmorillonite, and kaolinite) and massive silica hydrothermal breccias have formed.

 

Marbleization of limestone and dolomite units appears to be spatially associated with intrusive units and skarn related alteration.

 

6.5 Mineralization

 

At El Porvenir, mineralization is characterized as a skarn, intermediate sulphidation epithermal vein/breccia style, or stratabound mineralization in the Goyllarisquizga Formation.

 

Skarn related mineralization associated with the Milpo stock is paragenetically earlier, followed by hydrothermal mineralization. Skarn-related mineralization is commonly associated with the garnet and silica-skarn-chlorite assemblages, comprising pyrite, chalcopyrite, sphalerite, galena and minor pyrrhotite, pyrite, bornite, covellite, orpiment, and realgar within the Pucará Group sediments around the Milpo stock. Molybdenite may occur proximal to the skarn related mineralization. Elevated Bi and Au contents are reported to be associated with skarn related mineralization. Veins and veinlets with pyrite, chalcopyrite, sphalerite, galena, quartz, and carbonates occur within marble units, and are spatially associated with skarn bodies.

 

The silica breccia consists of sub-rounded to sub-angular white to milky grey opaline silica clasts, millimetres to centimetres in size, and to a lesser extent, sandstone, and limestone clasts. The silica breccia clasts are cemented by white granular silica, with occasional cross-cutting veins of white silica.

 

 

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The massive (siliceous) breccia forms zones of pervasive alteration comprising predominantly fine grained and massive white silica.

 

The granular (siliceous) breccia comprises loose white to grey grains of silica within a poorly cemented (undifferentiated) clay matrix.

 

The Ag-Pb-Zn breccias are subdivided into calcareous, polymictic-monomictic, and karst (collapse). Breccia clasts include limestone, marble, silica (massive), and skarn; the composition of the clasts indicates that brecciation occurred later than skarn development. Massive silica alteration may cross-cut skarns.

 

The calcareous breccia comprises sub-angular to sub-rounded clasts of limestone and marble, cemented by a grey to dark grey calcareous matrix, with occasional bituminous material and rare pyrite. Pyrite, sphalerite, galena, and other sulphides including orpiment, realgar, tetrahedrite, alabandite, stannite, as well as quartz, calcite, rhodochrosite and rhodonite occur within the matrix. The geochemical-mineralogical zoning is evident whereby galena (Pb) and Mn bearing minerals are more abundant distally relative to sphalerite (Zn). Bi and Sn bearing minerals are most elevated in the magmatic-hydrothermal system.

 

The polymictic to monomictic breccias are overall grey and comprise sub-angular clasts of black limestone, shale, white silica with veins of silica-pyrite, and marble with silica, wollastonite, and calcite. Monomictic breccias comprise sub-angular limestone or intrusive clasts. Polymictic and monomictic breccia clasts vary in size and are cemented with an amorphous black material with disseminated pyrite. Pyrite, chalcopyrite, sphalerite, galena, and possibly other sulphides occur within the matrix, forming veins/veinlets, pockets, or disseminations. Karst breccias contain clasts of limestone, marble, silica, skarn, and intrusive rocks. They are sub-angular to sub-rounded, occurring within a matrix of sub-horizontal laminated limestone and silica-sericite-clay material.

 

The stratabound Pb-Ag-Zn mineralization occurs in the sandstone strata (mantos) at the base of the Goyllarizquisga Formation (near the contact with the Pucará Group). Several disseminated sulphide mantos have recently been identified at Sara and Porvenir 2W within the quartz sandstone, generally in contact with layers of silt and microconglomerates. The minerals include galena with silver content, sphalerite, and pyrite. Gold is also present.

 

6.6 Deposit Types

 

Three types of mineral deposits are recognized at El Porvenir:

 

Skarn (exoskarn and endoskarn),

 

Intermediate sulphidation epithermal veins and breccias, and

 

Stratabound.

 

The description of the skarn deposit is largely derived from Einaudi and Burt (1982), Hammarstrom et al. (1991), and references therein. The hydrothermal vein deposit description is largely derived from Baumgartner et al. (2008) and references therein.

 

6.7 Skarn

 

Skarn deposits are generally considered as replacement style mineralization within or associated with carbonate dominant rocks. Skarns are classified as either endoskarn or exoskarn, referring to the location of skarn related mineralization either within an associated intrusive unit, or within carbonate lithology, respectively. Additionally, skarns can be divided into two broad groups: magnesian and calcic skarns, based on a dolomite dominated or limestone-dominated host lithology, respectively.

 

 

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Skarn development commonly includes metamorphic and metasomatic processes associated with carbonate and intrusive rocks, and an associated hydrothermal system. Mineralization occurs via a physio-chemical reaction between circulating hydrothermal fluids and the host lithology, and results in irregular shaped bodies. The hydrothermal system is generally believed to be related to and expelled from a cooling igneous body, which then undergoes a chemical reaction and cools as the fluid interacts with the usually carbonate dominant host lithology. The lithochemistry of the host rocks (i.e., Ca or Mg rich carbonate, or calc-silicate assemblage) strongly controls or influences mineralization. Replacement mineralogy commonly comprises Ca and Mg bearing silicates, however, Fe , Al, and Mn bearing minerals may also be important. Mineral and metal zonation is common. Three generalized dynamic processes responsible for the formation of all skarns are described as:

 

1. Isochemical contact metamorphism during pluton emplacement;

 

2. Prograde metasomatic (infiltration) skarn formation as the pluton cools and an ore fluid develops; and,

 

3. Retrograde alteration of earlier formed mineral assemblages.

 

The style of mineralization at El Porvenir appears to be best represented by the base and precious metal skarn category of the calcic skarn group. In terms of a conceptual model, Zn + Pb combined may average 10% to 15%, commonly with significant Ag (from 30 g/t to 300 g/t) as well as Cu, Au, and W. Copper mineralization commonly occurs proximal to the associated intrusive unit, whereas Zn and Pb mineralization typically occurs more distally to the associated intrusive. Mineralization commonly occurs as sulphides, including sphalerite, galena, chalcopyrite, and a variety of Ag-bearing sulphosalts. Gangue mineralogy may be dominated by Mn-bearing pyroxenes and garnet. Mineral textures vary from commonly coarse grained, associated with Ca rich host lithology and in close proximity to the related intrusion, to fine-grained, more distal and associated with calc-silicate rocks.

 

The tectonic setting of Zn-Pb skarns are commonly reported at continental margins and formed during syn- to late orogenic processes. Plutons are commonly absent but, if present, occur as stocks and dikes and may vary in composition from granite to granodiorite to syenite to diorite. Replacement mineralogy within carbonates is usually Fe, Mn, and S rich, and low in Al; and alteration within associated intrusions may comprise locally intense epidote, pyroxene, and garnet.

 

6.8 Hydrothermal Vein and Breccia

 

The hydrothermal veins and breccias at El Porvenir fall into a class of epithermal polymetallic base metal deposits (also referred to as Cordilleran base metal veins), which form in the upper parts of a magmatic-hydrothermal system (i.e., porphyry environment).

 

The Cordilleran base metal deposits have the following features:

 

Close temporal and spatial association with calc-alkaline intrusions;

 

Mineralization occurred under epithermal conditions (i.e., near Earth’s surface);

 

Sulphide-rich mineralogy, including a Cu-Zn-Pb-(Ag-Au-Bi) metal suite, and high Ag/Au ratio;

 

Well-developed mineral zonation and alteration minerals, with Zn-Pb mineralization formed more distally (Pb-Ag-Au assemblage in the upper zone and Cu-Au association in the deeper zones);

 

Early pyrite-quartz associated with low sulphidation mineralogy;

 

 

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Mineralization textures may be open-spacing filling in silicate host rocks, or as replacement in carbonate rocks; and

 

Mineralization occurred late in the temporal evolution of the magmatic-hydrothermal system.

 

Figure 6-7 is a schematic diagram showing the spatial relationship of skarn, replacement, and hydrothermal vein mineralization with intrusive rocks.

 

Figure 6-7:                Schematic Diagram of Skarn, Replacement and Hydrothermal Vein Mineralization

 

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Modified from Gilbert and Lowell, 1974

 

6.9 Stratabound

 

Stratabound deposits have been described by Fontboté, Amstutz, Cardozo et al. (1990), Fontboté defined stratabound deposit model as deposits formed through volcanogenic, hydrothermal, metamorphic, diagenetic, and sedimentary processes both penecontemporaneously and much later than the host rock, which can be volcanic or sedimentary.

 

The empirical link of ore and host rock can be used to classify the stratabound ore deposit according to the age and geotectonic position of the enclosing rock. A systematic classification could be achieved with ore deposits hosted by rocks of the Andean Cycle (Mesozoic-Recent) because the regional geology and geotectonic interpretation of the rocks of this period are well known. According to Fontboté (1990), three metallogenic “stages” can be distinguished in the Central Andes. Each stage is characterized by its tectonic style, magmatic activity, and basin evolution; and in each stage, characteristic types of stratabound deposits occur.

 

The sandstone hosted stratiform lead-zinc occurrences in the Goyllarisquizga Formation near Milpo were included by Samaniego (1982) in the Santa Metallotect, however, the possibility that they were formed by impregnation in relation with the Tertiary skarn deposits of the Milpo-Atacocha district (Soler 1986) is supported by lead isotopic data (Gunnesch and Baumann 1990).

 

 

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Figure 6-8:         Schematic Diagram of Stratabound Deposit at El Porvenir

 

 

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7.0 Exploration

 

7.1 Exploration

 

All exploration work at El Porvenir must be considered in the broader context of an integrated exploration program for the greater Atacocha Mine region. Nexa has been conducting exploration and development work at El Porvenir since 1949. The majority of this work is generally conducted simultaneously with underground development, which involves diamond core drilling, and channel sampling following underground drifting. Since 2019, surface diamond drilling has been carried out to identify mineralization in new areas, such as the Sara deposit which was discovered at the end of 2018. Prior to 1997, minor and sporadic exploration drilling was completed. No channel sampling is documented before 2001.

 

7.2 Integration of El Porvenir and Atacocha

 

In 2017, Nexa developed an underground connection (and integration) of the El Porvenir and Atacocha mines at the 3370 Level. At least four more of these connections were planned, and allow ample opportunities to conduct underground exploration drilling to test the volume which lies between the two mines. Figure 7-1 presents the El Porvenir and Atacocha mines with underground workings in relation to resource classifications and relevant infrastructure. In 2018, the Integration Zone was discovered at the 3300 Level, which consists of two mineralized zones, one hosted in hydrothermal breccias and one in skarn, and Nexa plans to continue exploration towards levels lower and higher than the 3300 Level.

 

 

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Figure 7-1:           El Porvenir and Atacocha Mines with Underground Workings

 

 

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7.3 2019 El Porvenir Exploration

 

Exploration in 2019 included 47,000 m of diamond core drilling, focused on defining new Inferred Mineral Resources at nine different targets such as Don Lucho, Exito, and Integration Zone underground, and Sara at surface. Nexa’s diamond exploration activities from the surface and underground at El Porvenir is generally carried out simultaneously with the underground development, which involves diamond drilling, mapping, sampling, interpretations of known mineralized zones extensions and Brownfield-type satellite targets. The El Porvenir exploration team carried out the following work during 2019:

 

Diamond drill core density sampling (10 cm to 15 cm, paraffin method) carried out at the Lima (ALS) laboratory.

 

Incorporation of Terraspec Halo logging, to obtain better knowledge of alteration and identify correlations of grade with any preferential alteration.

 

Measure orientations of existing core, in order to generate a better interpretation of the mineralized trends, faults, veins and strata.

 

7.4 2020 Exploration Program

 

Exploration activities for 2020 at El Porvenir were projected to complete 18,000 m of diamond drilling, however, only 16,126 m in 42 holes were completed due to COVID-19 pandemic restrictions. The drilling programs focused on the extensions of the Sara mineralized zone from surface, as well as the exploration to the north of Sara mineralization, from underground at the 4050 Level. A location map of the Sara deposit is shown in Figure 7-2.

 

As part of the “Full Potential” Program, exploration data acquisition and interpretation activities for 2020 focused on mineralogical alteration patterns and a surface magnetometric geophysical program, aiming to identify and define Brownfield exploration targets (Figure 7-3).

 

7.4.1 Sara Project

 

The Sara deposit, located to the southwest of the El Porvenir operation area, is hosted in the sandstones of the Gollarizquisga Group and consists of mineralization with intermediate sulphidation characteristics. Nexa staff have recognized two mantles with galena and sphalerite containing significant silver and, to a lesser extent, gold.

 

 

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Figure 7-2:            Sara Project Location Map and Example Section

 

 

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7.4.2 Alteration Studies

 

The following techniques to obtain a better definition of mineralogical alterations were carried out:

 

Remote sensing and advanced spaceborne thermal emission and reflection radiometer (ASTER) data analysis, to obtain superficial alteration anomalies, using the Crosta technique based on Principal Component Analysis (Figure 7-3).

 

TerraSpec Halo (a full-range near-infrared spectrometer) data collection and analysis, carried out within the Sara project, to identify alteration minerals and to delineate alteration anomalies.

 

7.4.3 Geophysics

 

In 2020, Nexa commissioned a MAGDRONE magnetometry program covering 488 km of lines over a 7,200 ha area in the Cerro Pasco Complex district extending from the Machcan area to the south of El Porvenir (Figure 7-4). The geophysical survey indicated the possible presence of subcropping intrusives as new exploration targets.

 

Level 2700 represents an important area for the expansion of El Porvenir. A plan section of the magnetometry data for Level 2700 is shown in Figure 7-5(a), projected to surface in Figure 7-5(b). Magnetometry showed five geophysical anomalies (Tingo, Carmen Chico NW, Carmen Chico W, La Quinua and Chicri), which will be studied through geological mapping programs, surface sampling, and diamond drilling in the next three years.

 

 

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Figure 7-3:          Remote Sensing and Alteration Anomalies

 

 

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Figure 7-4:          Geology, Flight Plan, and 3D Geophysical Model

 

 

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Figure 7-5:       Geophysical Anomalies at Level 2700

 

 

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7.4.4 Brownfield Exploration

 

The following brownfield projects (Figure 7-6) have been recognized through surface mapping and through subsequent work, including remote sensing process and geophysics:

 

Machcan: Vein outcrops and Angelica mantle with Ag, Pb, and Zn mineralization and magnetic anomalies.

 

Curiajasha: Northwest faulting, concordant with the dikes and with magnetic anomalies.

 

Longreras: Silicic breccia extending for more than two kilometres; the presence of Pb and Ag anomalies on surface and a magnetic anomaly to the south.

 

Manuel 05 and Pique Estrella: Follow the northwest structural trend; with some historic holes cutting vein mineralization.

 

La Churca: The intersection of the north-south Longreras fault and the east-west La Churca fault, and the presence of northeast oriented dikes on the surface, indicate good exploration potential.

 

La Quinua Chicrin Corridor: Remote sensing anomalies, with the presence of alunite, illite, and kaolinite, and the sandstone host rock in combination with a geophysical anomaly at depth indicate a high exploration potential.

 

 

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Figure 7-6:         Brownfield Targets of the Cerro Pasco Complex

 

 

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7.5 2021 Exploration Program

 

The exploration work planned for 2021 has a budget of $3.1 million and includes 18,000 m of diamond drilling, focused on defining new Mineral Resources in the Sara corridor, comprising the eastern part of the Milpo syncline in the Goyllarisquizga Formation, and the Integration Zone at the 3,300 Level underground.

 

The exploration criteria for 2021 drilling will be based on four components:

 

Stratigraphic correlation: It is evident that the Sara mineralization is hosted in a horizon of medium to coarse grained sandstones; therefore, exploration is focused on locating similar horizons.

 

Structural analysis: Exploration drilling is focused on identifying extensions of known deposits based on structural geology and interpretation.

 

Alteration: At Sara, Nexa identified that the alteration related to mineralization is associated with the presence of Illite and muscovite. Nexa will incorporate this new interpretation as a guide for exploration for this type of intermediate sulphidation, stratabound deposit.

 

Geophysics: Exploration at Sara showed that mineralization can be located at transitions between high and low magnetic values.

 

The SLR QP is of the opinion that Nexa’s exploration strategy, practice, and procedures are consistent with industry standards, and notes that Nexa’s strategy has delineated several targets which may expand production.

 

7.6 Drilling

 

7.6.1 Drilling Summary

 

As of February 15, 2020, a total of 4,664 drill holes for 762,848.57 m are included in the El Porvenir drilling database (Table 7-1). All drilling was diamond drilling (DDH), with the majority of the holes (4,598) completed from underground workings, and 66 holes completed from surface. Drilling has been done by various contractors.

 

A total of ten historic holes, with no survey records, missing geological data, and causing grade discrepancy with overlapped new holes, were excluded from the Mineral Resource estimate. In addition to this exclusion, a total of 11 holes were relocated into the Atacocha database, as they were drilled within the Atacocha concession. SLR concurs with Nexa’s list of holes excluded from the Mineral Resource estimate. Table 7-2 lists the drilling excluded from the Mineral Resource estimate, and Table 7-3 lists the drilling included in the Mineral Resource estimate.

 

In addition to drilling, a total of 17,127 channel samples were completed for 97,104.81 m between 1900 and 2017 (Table 7-4).

 

From February 16, 2020 to December 31, 2020, an additional 36 exploration diamond drill holes were completed for a total length of 14,246.80 m.

 

Figure 7-7 illustrates the locations of the drill holes at Porvenir. Figure 7-8 is a cross section illustrating the selected drill holes and related geological interpretation and Figure 7-9 shows channel sampling locations at the Mine (1900-2017).

 

 

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Table 7-1:             Drilling Summary at Porvenir 

Nexa Resources S.A. – El Porvenir Mine

 

    Surface Holes   Underground Holes   Total
Year   Number   Metres   Type   Number   Metres   Type   Number   Metres   Type
Pre-2006               789   145,120.07   DDH   789   145,120.07   DDH
2006               22   2,915.45   DDH   22   2,915.45   DDH
2008   14   638   DDH   87   17,554.74   DDH   101   18,192.74   DDH
2009   2   253.4   DDH   140   22,623.80   DDH   142   22,877.20   DDH
2010   4   376.1   DDH   143   23,651.37   DDH   147   24,027.47   DDH
2011               263   47,391.67   DDH   263   47,391.67   DDH
2012               323   56,550.90   DDH   323   56,550.90   DDH
2013               270   44,026.55   DDH   270   44,026.55   DDH
2014               258   37,782.60   DDH   258   37,782.60   DDH
2015               301   48,859.12   DDH   301   48,859.12   DDH
2016               386   64,204.70   DDH   386   64,204.70   DDH
2017               450   54,645.80   DDH   450   54,645.80   DDH
2018               459   72,236.10   DDH   459   72,236.10   DDH
2019   2   1,123.20   DDH   426   65,812.70   DDH   428   66,935.90   DDH
2020   44   16,885.90   DDH   281   40,196.40   DDH   325   57,082.30   DDH
Totals   66   4.00       4,598   743,571.97       4,664   762,848.57    

 

Table 7-2:            Summary of Drilling Excluded from Mineral Resource Estimate 

Nexa Resources S.A. – El Porvenir Mine

 

    Underground Holes   Total
Year   Number   Metres   Type   Number   Metres   Type
Pre-2006   13   3,892.05   DDH   13   3,892.05   DDH
EP2008   1   244.98   DDH   1   244.98   DDH
EP2011   2   361.2   DDH   2   361.2   DDH
EP2012   3   571.6   DDH   3   571.6   DDH
EP2013   1   170.7   DDH   1   170.7   DDH
EP2016   1   17.9   DDH   1   17.9   DDH
Totals   21   5,258.43       21   5,258.43    

 

Note. The drilling was excluded due to discrepancy with new holes and some of them were relocated to Atacocha database. 

 

 

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Table 7-3:             Summary of Drilling Included in Mineral Resource Estimate 

Nexa Resources S.A. – El Porvenir Mine

 

    Surface Holes   Underground Holes   Total
Year   Number   Metres   Type   Number   Metres   Type   Number   Metres   Type
Pre-2006               776   141,228.02   DDH   776   141,228.02   DDH
2006               22   2,915.45   DDH   22   2,915.45   DDH
2008   14   638   DDH   86   17,309.76   DDH   100   17,947.76   DDH
2009   2   253.4   DDH   140   22,623.80   DDH   142   22,877.20   DDH
2010   4   376.1   DDH   143   23,651.37   DDH   147   24,027.47   DDH
2011               261   47,030.47   DDH   261   47,030.47   DDH
2012               320   55,979.30   DDH   320   55,979.30   DDH
2013               269   43,855.85   DDH   269   43,855.85   DDH
2014               258   37,782.60   DDH   258   37,782.60   DDH
2015               301   48,859.12   DDH   301   48,859.12   DDH
2016               385   64,186.80   DDH   385   64,186.80   DDH
2017               450   54,645.80   DDH   450   54,645.80   DDH
2018               459   72,236.10   DDH   459   72,236.10   DDH
2019   2   1,123.20   DDH   426   65,812.70   DDH   428   66,935.90   DDH
2020   44   16,885.90   DDH   281   40,196.40   DDH   325   57,082.30   DDH
Totals   66   19,276.60       4,577   738,313.54       4,643   757,590.14    

 

Note. For the Leapfrog model all validated drill holes were used.

 

Table 7-4:               Channel Sampling Summary at Porvenir 

Nexa Resources S.A. – El Porvenir Mine

 

Year   Quantity   Metres   Type
Pre-2006   2,906.00   19,441.57   CHNL
2006   6,317.00   18,901.31   CHNL
2007   998.00   8,915.38   CHNL
2008   799.00   7,294.64   CHNL
2008   1,097.00   6,982.46   CHNL
2011   1,180.00   8,780.62   CHNL
2012   1,153.00   7,740.19   CHNL
2013   637.00   3,618.37   CHNL
2014   607.00   3,701.95   CHNL
2015   968.00   7,212.40   CHNL

 

 

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Year   Quantity   Metres   Type
2016   437.00   4,026.30   CHNL
2017   28.00   489.62   CHNL
Totals   17,127   97,104.81    

 

 

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Figure 7-7:                 Plan View of Drill Holes

 

 

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Figure 7-8:              Cross Section Showing Drill Holes and Geological Interpretation

 

 

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Figure 7-9:              Plan View of Channel Sampling

 

 

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7.6.2 Drilling Procedures

 

Drilling procedures are coordinated and supervised by company geologists (mine/production or exploration) and overseen by the Superintendent of Geology and Exploration. Drilling procedures are as follows:

 

Initially, drill hole collar coordinates and orientation are communicated to a mine surveyor to accurately position the drill hole and are then certified by the surveyor and validated by the responsible geologist. The coordinates and collar orientation data are entered into a master CSV file, subsequently imported into the database (Fusion) and geological/mine/modelling software program. Drill hole (and channel sample) identification is generated in a systematic and specific format, including codes to reference: country, mining unit, year, and sequential number. All related drill hole data generated is similarly referenced to the corresponding drill hole collar. Basic drill hole information (i.e., collar and survey) should be entered into the database and archived within four days of completing the drill hole.

 

Daily drilling logs completed and provided by the various contracted drilling companies are archived in PDF format.

 

Drill hole survey data is collected by various drilling contractors. The survey is generally carried out after the completion of the drill hole. Various survey equipment (i.e., Gyro, Reflex, Flexit, etc.) may be used depending on the drilling contractor and equipment availability; Gyro survey deviation information is archived in pdf format. Survey data are collected between approximately 5 m and 10 m downhole, depending on the drilling objective (infill and brownfield). Original survey data is marked on paper, and provided to the supervising geologist, signed by the driller in charge. Survey data is validated by the responsible geologist and entered into a master CSV file, subsequently imported into the database, and geological/mine/modelling software program.

 

Following the completion of a drill hole, the logging and core sampling procedures are carried out by a team of logging geologists. Core logging is completed using a set of geological, lithological, mineralogical, and alteration terms. Core logs are entered into logging software (Fusion). A complete series of core photos are taken for each drill hole and stored in JPEG or PDF format. Core sampling for geochemical analysis is essentially completed at the same time as core logging; see Section 8 for detailed description of drill core sampling procedures. Logging is completed within 48 hours after a drill hole is completed.

 

The company personnel responsible for managing the database incorporates the core logging and core sampling information, as well as the subsequent assay results once the analytical work is completed. Sample and assay data are initially combined in a master CSV file, subsequently imported into the database, and geological/mine/modelling software program.

 

Drilling information is stored in a structured directory and backed up on a central server (Brazil). Data available in the drill hole database includes drill hole location (Collar), downhole survey (Survey), sampling and geochemical analysis (Assay), recovery (Geotech), density (Density), and geological characteristics (Lithology, Alteration, Mineralization). Drill core diameter varies, including: BQ (36.4 mm), NQ (47.6 mm), HQ (63.5 mm), and TT-46 (35.3 mm).

 

7.6.3 Drilling Pattern and Density

 

Exploration drilling is generally completed over a 50 m by 50 m grid, whereas infill drilling is designed to cover a 15 m by 15 m grid. The overall distribution of drill holes and channel samples has been concentrated around the Carmen Norte 3, Exito, and Sara zones.

 

 

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7.6.4 Drill Rigs

 

At El Porvenir, there are two main categories of drilling: exploration and resource definition diamond drilling. Drilling is performed by the contractor Explomin.

 

7.6.4.1 Exploration Diamond Drilling

 

Exploration drilling is planned by the exploration team and its main objective is to discover new resources. It consists of underground (mine) drilling and surface drilling using Sandvik DE140 and versadrill 1.4U drilling machines, respectively. Exploration drilling is carried out with large drill rigs with a depth range of up to 1,000 m and HQ (63.5 mm) and NQ (47.6 mm) core sizes, and as required BQ (36.6 mm), are used.

 

7.6.4.2 Resource Definition Diamond Drilling

 

Resource definition drilling is the responsibility of the geological team and has the objective to upgrade known Inferred Mineral Resources to Measured or Indicated and thus increase the Mineral Reserves at Porvenir. This drilling consists of:

 

Recategorization, focused on the recategorization and definition of bodies where there is little drilling information.

 

Infill focused on providing additional information from short to long term planning to ensure the reliability of production programs.

 

Small drill rigs called drillcats are used with depth ranges of up to 400 m. Infill drilling generally uses BQ core size (to a depth of 240 m) and recategorization drilling uses NQ or BQ core size (to a depth of 400 m).

 

7.6.5 Core Recovery

 

Core recovery and rock quality designation (RQD) are measured and recorded for each hole. Core runs are 3.0 m for HQ and NQ and 1.5 m for BQ core size. Measurements are reviewed by geologists and the database administrator and then exported to the Fusion database.

 

Table 7-5 summarizes core recovery by domain from 2017 to 2020.

 

Table 7-5:            Core Recovery by Domain – 2017 to 2020 

Nexa Resources S.A. – El Porvenir Mine

 

Domain   No. Samples  

Minimum 

(%) 

 

Maximum 

(%) 

 

Mean 

(%) 

  Variance   Std.
Deviation
  CV
Don Ernesto   279   33.33   100   94.07   170.74   13.07   0.14
Don Lucho   469   2.23   100   93.41   319.73   17.88   0.19
Integración Ata Ep   386   48.85   100   97.43   54.64   7.39   0.08
Porvenir 3   815   32.63   100   98.23   71.25   8.44   0.09
Porvenir 2 Sur Este   1002   0.00   100   98.12   59.00   7.68   0.08
Porvenir 2 Sur Oeste   896   33.33   100   98.64   9.42   3.07   0.03
Sara   739   14.70   100   96.04   118.73   10.90   0.11
Socorro 2 and 4   265   81.82   100   99.23   2.59   1.61   0.02

 

 

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Domain   No. Samples  

Minimum 

(%) 

 

Maximum 

(%) 

 

Mean 

(%) 

  Variance   Std.
Deviation
  CV
Veta Am   529   20.00   100   98.04   54.01   7.35   0.07
Veta Carmen Norte 1   276   13.33   100   97.07   108.34   10.41   0.11
Veta Carmen Norte 3   1798   6.72   100   97.92   63.02   7.94   0.08
Veta Carmen Norte 4   197   86.21   100   98.43   6.46   2.54   0.03
Veta Carmen 2   104   88.33   100   98.74   9.00   3.00   0.03
Veta Carmen 3   321   54.55   100   98.73   15.46   3.93   0.04
Veta Progreso   15   98.59   100   99.71   0.26   0.51   0.01
Veta 1204   307   40.00   100   96.10   132.14   11.50   0.12
Veta 1204 Inferior   3   100.00   100   100.00   -   -   -
Veta 1204 Superior   3604   0.00   100   97.87   95.21   9.76   0.10
Veta 5   687   50.00   100   98.10   30.28   5.50   0.06
Éxito   3749   0.00   100   98.55   44.26   6.65   0.07

 

Notes:

 

Data encoded within the model.

 

For this analysis, 1,043 of 4,643 drill holes (22%) were used.

 

Based on core recovery statistics reviewed, and from the inspection of a number of drill holes, the SLR QP is of the opinion that the core recovery at Porvenir is excellent, generally greater than 95%, and provides a reliable reflection of the mineralization in the mining operation.

 

7.6.6 Drill Core Sampling

 

Drill core sampling is carried out under the supervision of the Sampling Geologist Supervisor and completed after the geotechnical and geological logging, and photographing the whole core following the Standard Operation Procedure (SOP) PO-EXP-GTO-009-PT.

 

The length of the samples varies between 0.30 m and 2.00 m depending on the structure and lithology. Once the sample length and cut-line have been defined by the supervising geologist, the core is cut longitudinally into two equal parts using an electric diamond drill core saw. If the core is very fractured, the sampler separates and removes 50% of the fragmented material for the sample. The fragments are deposited in a pre-coded polyethylene bag and transported to the laboratory.

 

Current exploration core sampling follows written protocols and consists of half-core sampling of HQ-or NQ sized core on (usually systematic) 1.5 m intervals. The remaining half-core is kept as backup. Major mineralized body contacts are respected.

 

Infill or resource definition drilling is typically BQ-sized core and is sampled in its entirety on 1.5 m intervals.

 

 

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7.6.7 Channel Sampling

 

Channel samples are treated as drill holes in the database, with a location, survey (direction: azimuth and inclination), and associated sampling/assay data. Table 10-4 lists the amount of channel sampling completed by year. Figure 7-9 illustrates the distribution of the channel sampling.

 

Channel chip samples are generally collected from the face of newly exposed underground workings. The entire process is carried out under the inspection of the sampling supervisor geologist.

 

Channel samples are collected between the hanging wall and footwall contacts of mineralized zones. A channel sample area is marked, oriented perpendicular to the strike of the mineralized structure. In general, the spacing between each channel sample is 2.0 m. The width of each channel sample is approximately 0.2 m to 0.3 m wide, and 2.0 cm deep. The sample area is first washed down to provide a clear view of the vein. The channel is sampled by taking a succession of chips in sequence from the hanging wall to the footwall. If the width of the vein, or length of the channel sample, is longer than 1.5 m, sample lengths shorter than 1.5 m are collected. If the width of the vein is smaller than 0.2 m, the width of the sample is increased to 0.4 m to obtain a sufficient sample size.

 

Sample collection is normally performed by two samplers, one using the hammer and chisel, and the other holding the receptacle cradle to collect the rock fragments. The cradle consists of a sack, with the mouth kept open by a wire ring. The collected sample material is then placed on a mat measuring 1.0 m by 1.2 m; the larger sample fragments are then broken down to smaller fragments, less than approximately 2.0 cm, using a four- or six-pound hammer. Subsequently, the sample material is mixed, and approximately one quarter of the mixed material is separated to obtain a representative sample (cone-and-quarter method), with a target weight of between 2.5 kg and 3.0 kg. The final sample is placed in a bag with a coded ticket and shipped to the Inspectorate laboratory at the mine site. Channel sampling was discontinued in 2017. In November 2019, Nexa re-started a channel sampling pilot, however, by the time of the database closure, the program was still in a preliminary stage and the channel samples were not included in the resource database. From November 2019 to February 15, 2020, a total of 187 channel totalling 1,028.05 m were sampled. Nexa reviewed this information and noted that overall there was good agreement with the resource model. SLR agrees with Nexa and recommends validating all channel samples collected between November 2019 and February 2020 to be included in the next Mineral Resource update. The SLR QP is of the opinion that the new information is not material to significantly impact the resource estimate.

 

7.6.8 Drilling and Channel Sampling Results

 

The results of analysis and interpretation of drilling data, and prior to 2017 channel sampling data, have been continually incorporated into the El Porvenir 3D geological model.

 

The database is used by modelling geologists who work together with the mine/production and exploration geologists to continually construct and update the 3D geological model. The 3D geological models are built in Leapfrog, primarily using geochemical assay results, particularly for Zn, Pb, Cu, and Ag, as well as underground geological level plan maps and interpreted cross sections and transverse sections.

 

In the SLR QP’s opinion, the drilling, logging, and drill core and channel sampling procedures meet industry standards. The SLR QP is not aware of any drilling, sampling, or recovery factors that could materially impact the accuracy and reliability of the results. 

 

 

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7.7 Hydrogeology Data

 

The El Porvenir Mine does not produce significant quantities of water. Details related to Hydrogeology are covered in Section 13.4.

 

7.8 Geotechnical Data

 

Geotechnical studies have been conducted at the El Porvenir Mine to characterize the quality of the rock mass to predict the stope and mine workings stability. Underground geotechnical mapping, geotechnical core logging and laboratory tests are part of Nexa geotechnical procedures. Nexa has performed laboratory testing in combination with geotechnical mapping and geotechnical logging to monitor the ground stability and to define parameters for ground support design of the underground workings as it is described in Section 13.3. The geotechnical logging, mapping, testing and data analysis protocols include industry-standard practices. 

 

 

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8.0 Sample Preparation, Analyses, and Security

 

8.1 Density Determinations

 

A total of 4,876 density samples were taken from 2009 to 2020 at the El Porvenir deposit and were tested by various laboratories. Nexa used Certimin and ALS as independent laboratories for density determinations. A summary of the density measurements taken is presented in Table 8-1.

 

Density samples were 10 cm to 20 cm lengths of the entire core, taken from a variety of lithological and mineralogical types. Photographs and brief descriptions were taken before sending the samples to the laboratory for density determinations. Density data is recorded in the main database.

 

A total of 1,131 samples were collected from mineralized zones (Figure 8-1) and a total of 3,745 samples were collected from waste rocks. For the mineralized zones, an average density value was applied. In the absence of sufficient data, Nexa has assigned an average density value of surrounding mineralized zones or the global average density value of all the mineralized zones.

 

ALS Peru S.A. and Certimin laboratories use the water immersion method to determine the density of the provided samples. This method consists of coating the sample in paraffin wax, weighing the sample in air, then suspending the sample in water, and weighing the sample again.

 

From 2014 to 2016, an on-site trained technician weighted the sample in air, then suspended the sample in water and measured the volume of displaced water. Currently density measurements are performed by external laboratories.

 

Table 8-1:              Number of Density Measurements by Sample Type and Year 

Nexa Resources S.A. – El Porvenir Mine

  

Phase 

Sample Type

 All No. Samples

No. Samples within
Mineralization Zones

LOM2009 Drill Holes 5 -
LOM2011 Rock 686 246
LOM2012 Rock 18 6
LOM2014 Drill Holes 267 72
  Rock 62 2
LOM2015 Drill Holes 536 120
  Rock 229 50
LOM2016 Drill Holes 375 117
  Rock 236 53
LOM2017 Drill Holes 386 99
LOM2018 Drill Holes 317 75
  Rock 86 20
LOM2019 Drill Holes 834 105
LOM2020 Drill Holes 839 166
Total   4876 1,131

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Figure 8-1:                Distribution of Density Samples Used for 2020 Mineral Resource Estimate by Year Analyzed 

 

 

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8.2 Sample Preparation and Analysis

 

The core and channels samples are sent to several independent laboratories including Inspectorate (at the Mine, referred to subsequently as Inspectorate EP), SGS (at the Mine), ALS (Lima), and Certimin (Lima). Testing protocols among these laboratories differ in their detection limits and methods applied. El Porvenir has a contract with Inspectorate, which began its operations in 2011, and with ALS in 2018. SGS served as the Mine laboratory from 2006 to 2009. Exploration samples were sent to Certimin in 2017 and 2018.

 

Inspectorate is an independent and commercial laboratory, and is part of the Bureau Veritas, which is a global leader in testing, inspection, and certification. Certimin Lima holds ISO 9001 and NTP-ISO/IEC 17025 and 17021 certifications and is accredited by the Organismo Peruano de Acreditación (INACAL). ALS geochemical laboratories are accredited to ISO/IEC 17025:2005 for specific analytical procedures. Both Certimin and ALS laboratories are independent of Nexa.

 

Sampling was completed by Nexa geologists following standard operating procedures. Figure 8-2 illustrates a schematic flow chart of sample control, as well as the transfer of related data, and personnel units responsible for each respective area.

 

Exploration drilling samples are sent to ALS Lima, and mine drilling samples are sent to Inspectorate EP for preparation and analysis. Prepared samples are assayed principally for a suite of seven elements: Zn, Pb, Cu, Ag, Au, Bi, and Mn. Samples are initially coded and dried at 105°C to a maximum of 120°C. Following drying, the samples are crushed to a minimum of 70% passing minus two millimetres. The crushed samples are then reduced in size by passing the entire sample through a riffle splitter until 200 g to 250 g is obtained. The split samples are then pulverized to a minimum of 85% passing 75 μm. The pulverized samples are subsequently analyzed using an aqua regia digestion and atomic absorption spectroscopy (AAS).

 

Detection limits for Inspectorate EP, ALS Lima, and Certimin are summarized in Table 8-2.

 

Table 8-2:                Laboratory Detection Limits 

Nexa Resources S.A. – El Porvenir Mine

 

Laboratory  

Element 

Unit 

Method 

Detection
Lower
Limit 

Detection
Upper
Limit 

1st  Upper Limit Default
Method 

2nd Upper
Limit Default
Method 

Inspectorate EP Ag ppm F-AA 4 - GRA -
  Cu per F-AA 0.01 30 VOL -
  Fe per F-AA 0.01 - - -
  Mn per F-AA 0.01 - - -
  Pb per F-AA 0.01 30 VOL -
  Zn per F-AA 0.01 30 VOL -
ALS Au ppm Au-AA23 0.005 10 Au-GRA21 -
  Ag ppm ME-ICP41 0.2 100 Ag-OG46 Ag-GRA21
  Al per ME-ICP41 0.01 25 - -
  As ppm ME-ICP41 2 10000 - -

 

 

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Laboratory  

Element 

Unit

Method

Detection
Lower
Limit

Detection
Upper
Limit

1st  Upper Limit Default
Method

2nd Upper
Limit Default
Method

  B ppm ME-ICP41 10 10000 - -
  Ba ppm ME-ICP41 10 10000 - -
  Be ppm ME-ICP41 0.5 1000 - -
  Bi per ME-ICP41 0.0002 1 - -
  Ca per ME-ICP41 0.01 25 - -
  Cd ppm ME-ICP41 0.5 1000 - -
  Co ppm ME-ICP41 1 10000 - -
  Cr ppm ME-ICP41 1 10000 - -
  Cu per ME-ICP41 0.0001 1 Cu-OG46 -
  Fe per ME-ICP41 0.01 50 Fe-OG46 -
  Ga ppm ME-ICP41 10 10000 - -
  Hg ppm ME-ICP41 1 10000 - -
  K per ME-ICP41 0.01 10 - -
  La ppm ME-ICP41 10 10000 - -
  Mg per ME-ICP41 0.01 25 - -
  Mn per ME-ICP41 0.0005 5 Mn-OG46 -
  Mo ppm ME-ICP41 1 10000 - -
  Na per ME-ICP41 0.01 10 - -
  Ni ppm ME-ICP41 1 10000 - -
  P ppm ME-ICP41 10 10000 - -
  Pb per ME-ICP41 0.0002 1 Pb-OG46 Pb-VOL70
  S per ME-ICP41 0.01 10 - -
  Sb ppm ME-ICP41 2 10000 - -
  Sc ppm ME-ICP41 1 10000 - -
  Sr ppm ME-ICP41 1 10000 - -
  Th ppm ME-ICP41 20 10000 - -
  Ti per ME-ICP41 0.01 10 - -
  Tl ppm ME-ICP41 10 10000 - -
  U ppm ME-ICP41 10 10000 - -
  V ppm ME-ICP41 1 10000 - -
  W ppm ME-ICP41 10 10000 - -
  Zn per ME-ICP41 0.0002 1 Zn-OG46 Zn-VOL70

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Laboratory 

Element

Unit

Method

Detection
Lower
Limit

Detection
Upper
Limit

1st  Upper Limit Default
Method

2nd Upper
Limit Default
Method

Certimin Au ppm G0108 0.005 10 G0014 -
  Ag ppm G0148 0.2 100 G0001 G0008
  Al per G0148 0.01 15 - -
  As ppm G0148 3 10000 - -
  Ba ppm G0148 1 10000 - -
  Be ppm G0148 0.5 10000 - -
  Bi per G0148 0.0005 1 - -
  Ca per G0148 0.01 15 - -
  Cd ppm G0148 1 10000 - -
  Co ppm G0148 1 10000 - -
  Cr ppm G0148 1 10000 - -
  Cu per G0148 0.00005 1 G0038 -
  Fe per G0148 0.01 15 G0051 -
  Ga ppm G0148 10 10000 - -
  Hg ppm G0148 1 10000 - -
  K per G0148 0.01 15 - -
  La ppm G0148 0.5 10000 - -
  Mg per G0148 0.01 15 - -
  Mn per G0148 0.0002 1 G0060 -
  Mo ppm G0148 1 10000 - -
  Na per G0148 0.01 15 - -
  Ni ppm G0148 1 10000 - -
  P per G0148 0.01 15 - -
  Pb per G0148 0.0002 1 G0076 G0339
  S per G0148 0.01 10 - -
  Sb ppm G0148 5 10000 - -
  Sc ppm G0148 0.5 10000 - -
  Sr ppm G0148 0.5 5000 - -
  Th ppm G0148 50 10000 - -
  Ti per G0148 0.01 15 - -
  Tl ppm G0148 2 10000 - -
  U ppm G0148 50 10000 - -
  V ppm G0148 2 10000 - -
  W ppm G0148 10 10000 - -
  Zn per G0148 0.00005 1 G0387 G0338

 

 

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Figure 8-2:              Schematic Flow Chart for Sample and Data Controls

 

8.3 Quality Assurance and Quality Control

 

El Porvenir has historical data and information up to February 15, 2020, the cut-off date for the resource database, and has implemented a quality assurance/quality control (QA/QC) program. These processes comply with current industry best practices which involve appropriate procedures and routine insertion of certified reference materials (CRM), standards, blanks, and duplicates to monitor the sampling, sample preparation, and analytical processes. Analysis of QA/QC data is performed to assess the reliability of all sample assay data and the confidence in the data used for resource estimation.

 

Quality control samples have been inserted into the sample stream since 2014 and channel samples since 2012. El Porvenir routinely sends in-house CRMs, blanks, field, reject (preparation), and pulp (laboratory) duplicates to the laboratory. During 2018, Nexa incorporated systematic external checks into the QA/QC program. Check assay programs were also carried out prior to 2018. Pulps were sent to external laboratories for analysis. Currently, Inspectorate EP and ALS analyze samples from infill drilling and brownfield exploration drilling, respectively.

 

During the 2006 to 2009 drilling campaign, samples were sent to SGS for analysis. From 2010 to present, underground infill drilling samples are sent to Inspectorate EP. If Inspectorate EP is running out of capacity, samples are delivered to Certimin and/or ALS laboratories.

 

8.3.1 QA/QC Protocols

 

Nexa has the following QA/QC protocols in place.

 

For infill and exploration drilling, one batch of samples is prepared for each drill hole. Control sample insertion rates are provided in Table 8-3, with field duplicates inserted directly following the original sample, coarse blank material samples inserted following a mineralized zone, and CRM samples inserted randomly.

 

 

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All QA/QC sample insertions maintain consecutive numerical order. Pulp reject duplicates, an additional split of material taken after the pulverizing stage, are saved, and then resubmitted to the secondary laboratory at a later date at a rate of approximately 2% of the total samples submitted.

 

Each batch of check samples (pulp rejects) submitted to the secondary laboratory includes CRM and blank samples.

 

QA/QC samples represent approximately 16% of the total samples. A QA/QC report is prepared monthly, by the onsite Database Administrator, and reviewed by the Resource Geologist and Nexa corporate QA/QC coordinator in San Paulo. Batches of samples identified by a QA/QC review as an anomalous result are repeated by the laboratory at the request of the Geology team. Table 8-3 shows the control sample insertion rate and the acceptance criteria followed during Nexa’s QA/QC program for El Porvenir.

 

Table 8-3:             Control Sample Insertion Rate and Failure Criteria 

Nexa Resources S.A. – El Porvenir Mine

 

Control Sample

Type

Insertion
Rate

Failure
Criteria

Expected/Allowed
% Failures

Blanks   1 in 50 (2%) 5 x DL <5%
CRMs   1 in 20 (5%) Outside 3 STD <10%
Duplicates Twin 1 in 100 (1%) <±30% relative error <10%
  Coarse 1 in 100 (1%) <±20% relative error <10%
  Pulp 1 in 20 (5%) <±10% relative error <10%
External checks Pulp 1 in 50 (2%) <5% bias <10%

 

A QA/QC relational database is maintained in Fusion. A summary of QA/QC submittals from 2014 to 2020 is presented in Table 8-4.

 

The actual insertion rates vary slightly by year and sample type.

 

Table 8-4:                QC Insertion Rates 

Nexa Resources S.A. – El Porvenir Mine

 

Year

Control

Type

Drill Holes

Channel

No.
Samples

Insertion
Rate
(%)

No.
Samples

Insertion
Rate
(%)

  Blanks Pulp 901 2.97 393 3.85
    Coarse 899 2.96 392 3.84
    Low Grade 449 1.43 - -
2014 – Sep. 2017 In-House CRMs Intermediate Grade 682 2.18 375 3.37
    High Grade 633 2.02 378 3.40
    Field 793 2.53 245 2.20
  Duplicates Coarse 689 2.20 174 1.56
    Pulps 715 2.28 195 1.75
  All Control Samples 5,761 18.36 2152 19.97

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Year

Control

Type

Drill Holes

Channel

No.
Samples

Insertion
Rate
(%)

No.
Samples

Insertion
Rate
(%)

  Blanks Pulp 959 2.51 - -
    Coarse 956 2.50 - -
    Low Grade 694 1.82 - -
  In-House CRMs Intermediate Grade 624 1.63 - -
Nov. 2017 - Aug. 2018   High Grade 586 1.53 - -
    Field 956 2.50 - -
  Duplicates Coarse 952 2.49 - -
    Pulps 951 2.49 - -
    Check Assay 747 1.96 - -
  All Control Samples 7,425 19.44 - -
  Blanks Pulp 1,641 2.48 - -
    Coarse 1,638 2.48 - -
    Low Grade 1,069 1.62 - -
  In-House CRMs Intermediate Grade 1,464 2.22 - -
Aug. 2018 - May. 2019   High Grade 639 0.97 - -
    Field 1,458 2.21 - -
    Coarse 1,652 2.50 - -
  Duplicates Pulps 1,687 2.56 - -
    Check Assay 641 0.97 - -
  All Control Samples 11,890 18.01 - -
  Blanks Coarse 1,227 2.22 - -
    Low Grade 1,155 2.09 - -
  In-House CRMs Intermediate Grade 1,159 2.10 - -
Jun. 2019 - Feb. 2020   High Grade 409 0.74 - -
    Field 830 1.50 - -
    Coarse 1,036 1.88 - -
  Duplicates Pulps 2,047 3.71 - -
    Check Assay 388 0.70 - -
  All Control Samples 8,251 14.94 - -

 

8.3.2 Certified Reference Material

 

Results from the regular submission of CRMs, prepared in-house and certified by accredited laboratories, are analyzed to identify problems with specific sample batches and long term biases associated with the assay laboratories. CRMs were inserted into the sample stream by technicians trained in quality control procedures. CRMs values since 2014 are detailed in Table 8-5. Ten CRMs using in-house material were certified by Target Rocks Peru S.A.C. (MAT-05, MAT-06, MAT11, MAT12, PEPSSTD001, PEPSSTD002, PEPSSTD003, PEPSSTD004, PEPSSTD005, PEPSSTD006), six standards (EMEI2240_2012 and “STD” pre-fixes) were certified by Actlabs Skyline Perú S.A.C., and three CRMs ( PEPSSTDAGA-05, PEPSSTDPLA-06, PEPSSTDPLM-04) were certified by Smee & Associates Consulting Ltd.

 

 

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Table 8-5:          CRMs Used at Porvenir Since 2014 

Nexa Resources S.A. – El Porvenir Mine

 

Laboratory

Method

Standard

Au (g/t)

Ag (oz/t)

Ag (ppm)

Pb (%)

Zn (%)

Cu (%)

Best Value

Std Dev

Best Value

Std Dev

Best Value

Std Dev

Best Value

Std Dev

Best Value

Std Dev

Best Value

Std Dev

    PEPSSTDAGA-05 0.48 0.04 16.65 1.03     1.67 0.09 2.19 0.10 0.26 0.01
Smee and Assoc. Consulting

Four  

acid - AAS

 

PEPSSTDPLA-06 0.36 0.01 5.63 0.26     5.37 0.25 6.08 0.24 0.48 0.01
    PEPSSTDPLM-04 0.20 0.01 2.96 0.26     1.94 0.13 2.44 0.12 0.16 0.01
    MAT-05     4.12 0.25     2.37 0.06 2.50 0.12 0.58 0.02
    MAT-06     15.08 0.42     7.75 0.20 7.98 0.23 2.53 0.12
  Four acid Digestion – AAS MAT11 0.93 0.09 1.76 0.11     1.37 0.04 2.19 0.13 0.17 0.01
    MAT12 8.98 0.48         6.83 0.21 6.95 0.24 0.18 0.00
    PEPSSTD001 0.07 0.01 0.44 0.02 13.80 0.60 0.41 0.01 1.02 0.06 0.07 0.00
    PEPSSTD002 0.24 0.03 1.58 0.09 49.10 2.70 1.48 0.09 3.14 0.12 0.07 0.00
Target Rocks AR Digestion - AAS PEPSSTD003 2.36 0.16 7.81 0.23 243.00 7.10 5.79 0.14 7.34 0.18 0.18 0.01
    PEPSSTD004 0.32 0.01     23.30 0.54 0.46 0.02 0.57 0.02 0.05 0.00
    PEPSSTD005 0.53 0.02     40.80 1.44 1.15 0.03 1.52 0.03 0.06 0.00
    PEPSSTD006 0.44 0.01     185.00 3.51 4.17 0.10 6.63 0.11 0.19 0.00
  Four acid Digestion – AAS EMEI2240_2012     0.78 0.06     0.08 0.00 2.66 0.10 0.49 0.03
    STD2_ACTLABS2014     0.93 0.06     0.46 0.02 3.07 0.08 0.36 0.01
ACTLABS   STD3_ACTLABS2014     3.72 0.17     3.62 0.10 7.34 0.31 0.21 0.01
  Mult acid Digestion – AAS STD1_ACTLABS2015     0.46 0.10     0.39 0.02 0.78 0.02 0.15 0.01
    STD2_ACTLABS2015     1.44 0.17     1.26 0.03 4.00 0.07 0.20 0.01
    STD3_ACTLABS2015     3.13 0.31     3.04 0.07 6.72 0.27 0.27 0.01

  

8.3.2.1 Milpo, 2014 to 2017

 

This section has mostly been summarized from SRK (2017).

 

CRMs were used to assess the accuracy of the assay results from Inspectorate EP, they were placed into the sample stream by geologist to monitor accuracy of the analytical process. The database recorded 31,314 drill core samples with 1,764 standards (a submission rate of 1 in 18 samples) submitted in 2014 and 2017 and 11,129 channel samples with 753 standards (a submission rate of 1 in 15 samples) submitted between 2014 and 2016. Prior to 2014, El Porvenir did not have a QA/QC program implemented.

 

 

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Pass rates reported for standards submitted with drill core samples were 99 % for silver, 84% for lead, 97% for zinc, and 99% for copper. The accuracy levels for silver, zinc, and copper can be considered acceptable while lead is below acceptable levels. Pass rates reported for standards submitted with channel samples were 99% for silver, 77% for lead, 96% for zinc, and 99% for copper. The accuracy levels for silver, zinc, and copper can be considered acceptable, however, lead performance should be improved. In both cases, (channel and drill core) MAT-05, STD2_ACTLABS2015 and STD3_ACTLABS2015 show values below 80%. SRK identified minor biases in some of the standards, Table 8-6 presents the CRMs performance.

 

Table 8-6:             2014 to 2017 CRMs Performance 

Nexa Resources S.A. – El Porvenir Mine

 

Metal

Standard

No.
Submitted

No.
Fails

Pass
(%)

Best
Value

Mean

Bias

    MAT-05 200 5 98 4.12 4.04 1.98%
    MAT-06 204 7 97 15.08 15.02 0.40%
    STD1_ACTLABS2015 449 0 100 0.46 0.46 0.00%
  Ag (oz) STD2_ACTLABS2014 97 6 94 0.93 0.97 -4.12%
    STD2_ACTLABS2015 385 0 100 1.44 1.44 0.00%
    STD3_ACTLABS2014 117 0 100 3.72 3.74 -0.53%
    STD3_ACTLABS2015 312 0 100 3.13 3.14 -0.32%
    Total 1,764 18 99      
    MAT-05 200 44 78 2.37 2.42 -2.07%
    MAT-06 204 4 98 7.75 7.8 -0.64%
    STD1_ACTLABS2015 449 0 100 0.39 0.4 -2.50%
  Pb (%) STD2_ACTLABS2014 97 0 100 0.46 0.48 -4.17%
    STD2_ACTLABS2015 385 142 63 1.26 1.3 -3.08%
Drill Hole
Samples
  STD3_ACTLABS2014 117 1 99 3.62 3.64 -0.55%
    STD3_ACTLABS2015 312 117 62 3.04 3.12 -2.56%
    Total 1,764 308 84      
    MAT-05 200 2 99 2.5 2.49 0.40%
    MAT-06 204 1 100 7.98 7.82 2.05%
    STD1_ACTLABS2015 449 42 91 0.78 0.76 2.63%
  Zn (%) STD2_ACTLABS2014 97 19 80 3.07 3.01 1.99%
    STD2_ACTLABS2015 385 32 92 4.00 3.97 0.76%
    STD3_ACTLABS2014 117 0 100 7.34 7.18 2.23%
    STD3_ACTLABS2015 312 0 100 6.72 6.75 -0.44%
    Total 1,764 96 95      
    MAT-05 200 8 96 0.58 0.56 3.57%
    MAT-06 204 2 99 2.53 2.55 -0.78%
  Cu (%) STD1_ACTLABS2015 449 0 100 0.15 0.15 0.00%
    STD2_ACTLABS2014 97 2 98 0.36 0.36 0.00%
    STD2_ACTLABS2015 385 0 100 0.2 0.2 0.00%
    STD3_ACTLABS2014 117 1 99 0.21 0.21 0.00%
    STD3_ACTLABS2015 312 3 99 0.27 0.27 0.00%
    Total 1,764 16 99      

 

 

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Metal

Standard

No.
Submitted

No.
Fails

Pass
(%)

Best
Value

Mean

Bias

    MAT-05 9 0 100 4.12 3.98 3.52%
    MAT-06 10 3 70 15.08 14.67 2.79%
    STD2_ACTLABS2014 178 3 98 0.93 0.96 -3.12%
  Ag (oz) STD2_ACTLABS2015 188 0 100 1.44 1.44 0.00%
    STD3_ACTLABS2014 217 1 100 3.72 3.74 -0.53%
    STD3_ACTLABS2015 151 0 100 3.13 3.13 0.00%
    Total 753 7 99      
    MAT-05 9 7 22 2.37 2.5 -5.20%
    MAT-06 10 0 100 7.75 7.87 -1.52%
    STD2_ACTLABS2014 178 2 99 0.46 0.48 -4.17%
  Pb (%) STD2_ACTLABS2015 188 104 47 1.26 1.3 -3.08%
Channel
Sample
  STD3_ACTLABS2014 217 5 98 3.62 3.66 -1.09%
    STD3_ACTLABS2015 151 54 64 3.04 3.12 -2.56%
    Total 753 172 77      
    MAT-05 9 0 100 2.5 2.5 0.00%
    MAT-06 10 0 100 7.98 7.84 1.79%
    STD2_ACTLABS2014 178 10 94 3.07 3.02 1.66%
  Zn (%) STD2_ACTLABS2015 188 18 90 4 3.97 0.76%
    STD3_ACTLABS2014 217 0 100 7.34 7.19 2.09%
    STD3_ACTLABS2015 151 0 100 6.72 6.77 -0.74%
    Total 753 28 96      
    MAT-05 9 1 89 0.58 0.55 5.45%
    MAT-06 10 0 100 2.53 2.59 -2.32%
  Cu (%) STD2_ACTLABS2014 178 3 98 0.36 0.36 0.00%
    STD2_ACTLABS2015 188 0 100 0.2 0.2 0.00%
    STD3_ACTLABS2014 217 1 100 0.21 0.21 0.00%
    STD3_ACTLABS2015 151 2 99 0.27 0.27 0.00%
    Total 753 7 99      

 

8.3.2.2 Nexa, November 2017 to 2020

 

Since November 2017, El Porvenir sent to Certimin, Inspectorate EP, and ALS a total of 139,319 drill core samples and 7,799 CRMs resulting in an insertion rate of 4.7%.

 

 

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Table 8-7 lists the certified values of the CRMs for Zn, Pb, Cu, and Ag, and the summary of the assay performance for the CRMs. Figure 8-3 and Figure 8-4 illustrate examples of the zinc and lead CRM results from the Mine for the 2018 to 2019 period.

 

 

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Table 8-7: 2017 to 2020 CRM Performance

 

Period

Laboratory

Analytical Method

Type Standard

Element

No. Samples

Best Value

Mean

Bias

No. Samples Outside 3SD

Failure Rate

        Ag oz/t 106 0.46 0.46 -0.20% 0 0%
      Low Grade Cu % 106 0.15 0.16 2.90% 0 0%
      STD1_ACTLABS2015 Pb % 106 0.39 0.4 3.10% 0 0%
        Zn % 106 0.78 0.77 -0.90% 0 0%
        Ag oz/t 60 0.93 0.98 5.00% 0 0%
      Medium Grade Cu % 60 0.36 0.36 0.30% 2 3%
      STD2_ACTLABS2014 Pb % 60 0.46 0.46 1.00% 2 3%
        Zn % 60 3.07 2.97 -3.30% 1 2%
    Mult acid Digestion - AAS   Ag oz/t 101 3.72 3.9 4.90% 3 3%
      High Grade Cu % 101 0.21 0.21 -0.10% 4 4%
      STD3_ACTLABS2014 Pb % 101 3.62 3.6 -0.60% 4 4%
        Zn % 101 7.34 7.3 -0.60% 3 3%
        Ag oz/t 67 3.13 3.19 2.10% 0 0%
      High Grade Cu % 67 0.27 0.27 1.20% 0 0%
      STD3_ACTLABS2015 Pb % 67 3.04 3.08 1.20% 0 0%
  Certimin     Zn % 67 6.72 6.64 -1.20% 0 0%
        Au ppm 354 0.07 0.07 7.00% 4 1%
        Ag oz/t 354 0.44 0.44 -0.20% 2 1%
      Low Grade Cu % 354 0.07 0.07 1.60% 11 3%
      PEPSSTD001 Pb % 354 0.41 0.41 1.40% 9 3%
        Zn % 354 1.02 1.03 0.50% 17 5%
        Au ppm 360 0.24 0.25 4.10% 16 4%
    AR Digestion - AAS Medium Grade Ag oz/t 360 1.58 1.47 -7.10% 2 1%
    PEPSSTD002 Cu % 360 0.07 0.07 0.50% 3 1%
        Pb % 360 1.48 1.52 2.80% 5 1%
        Zn % 360 3.14 3.1 -1.30% 4 1%
        Au ppm 178 2.36 2.4 1.70% 2 1%
        Ag oz/t 178 7.81 7.78 -0.40% 1 1%
      High Grade Cu % 178 0.18 0.19 4.50% 2 1%
Nov. 2017 - Aug. 2018     PEPSSTD003 Pb % 178 5.79 5.86 1.30% 3 2%
        Zn % 178 7.34 7.37 0.40% 2 1%
        Ag oz/t 100 0.46 0.45 -2.00% 2 2%
      Low Grade Cu % 100 0.15 0.16 1.40% 3 3%
      STD1_ACTLABS2015 Pb % 100 0.39 0.4 2.20% 0 0%
        Zn % 100 0.78 0.76 -2.10% 1 1%
        Ag oz/t 34 0.93 1.03 10.80% 0 0%
      Medium Grade Cu % 34 0.36 0.36 -0.30% 0 0%
      STD2_ACTLABS2014 Pb % 34 0.46 0.46 -0.80% 0 0%
    Mult Acid Digestion - AAS   Zn % 34 3.07 2.97 -3.40% 0 0%
        Ag oz/t 40 3.72 3.73 0.30% 0 0%
      High Grade Cu % 40 0.21 0.21 -0.40% 0 0%
      STD3_ACTLABS2014 Pb % 40 3.62 3.64 0.50% 1 3%
        Zn % 40 7.34 7.17 2.30% - 0 0%
        Ag oz/t 94 3.13 3.1 -0.90% 1 1%
      High Grade Cu % 94 0.27 0.27 0.10% 0 0%
  Inspectorate EP   STD3_ACTLABS2015 Pb % 94 3.04 3.12 2.50% 1 1%
        Zn % 94 6.72 6.72 0.10% 0 0%
        Ag oz/t 134 0.44 0.46 4.80% 1 1%
      Low Grade Cu % 134 0.07 0.07 6.40% 0 0%
      PEPSSTD001 Pb % 134 0.41 0.41 2.00% 1 1%
        Zn % 134 1.02 1.02 0.00% 0 0%
        Ag oz/t 170 1.58 1.54 -2.80% 1 1%
      Medium Grade Cu % 170 0.07 0.07 5.10% 1 1%
    AR Digestion - AAS PEPSSTD002 Pb % 170 1.48 1.53 3.10% 1 1%
        Zn % 170 3.14 3.08 - 1.90% 1 1%
        Ag oz/t 106 7.81 7.44 -4.80% 0 0%
      High Grade Cu % 106 0.18 0.19 2.10% 0 0%
      PEPSSTD003 Pb % 106 5.79 5.6 -3.20% 0 0%
        Zn % 106 7.34 7.39 0.70% 0 0%
        Au ppm 278 0.065 0.069 6.32% 0 0%
        Ag oz/t 52 0.444 0.448 0.88% 0 0%
      Low Grade Ag ppm 226 13.8 13.88 0.57% 0 0%
      PEPSSTD001 Cu % 278 0.071 0.071 0.41% 0 0%
        Pb % 278 0.406 0.412 1.43% 0 0%
        Zn % 278 1.02 1.028 0.80% 0 0%
        Au ppm 268 0.239 0.247 3.53% 0 0%
        Ag oz/t 47 1.579 1.461 -7.47% 0 0%
  Certimin AR Digestion- AAS Medium Grade Ag ppm 221 49.1 45.64 -7.04% 3 1%
      PEPSSTD002 Cu % 268 0.07 0.07 0.64% 0 0%
        Pb % 268 1.48 1.523 2.88% 0 0%
        Zn % 268 3.14 3.1 -1.14% 0 0%
        Au ppm 86 2.358 2.396 1.62% 0 0%
        Ag ppm 86 243 241.79 -0.50% 0 0%
      High Grade Cu % 86 0.183 0.192 4.69% 0 0%
      PEPSSTD003 Pb % 86 5.79 5.88 1.51% 0 0%
        Zn % 86 7.34 7.38 0.56% 1 1%
        Ag ppm 111 8.7 9.08 4.38% 0 0%
      Low Grade Au ppm 110 0.249 0.253 1.52% 4 4%
      MAT10 Cu % 111 0.252 0.266 5.82% 3 3%
        Pb % 111 0.113 0.114 1.45% 0 0%
        Zn % 111 0.301 0.285 -5.16% 0 0%

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Period

Laboratory

Analytical Method

Type Standard

Element

No. Samples

Best Value

Mean

Bias

No. Samples Outside 3SD

Failure Rate

        Ag ppm 492 54.6 56.61 3.68% 31 6%
        Au ppm 519 0.932 0.935 0.36% 3 1%
    Four Acid Digestion - AAS Medium Grade Cu % 521 0.171 0.176 3.13% 12 2%
      MAT11 Pb % 521 1.37 1.341 -2.15% 13 2%
        Zn % 521 2.19 2.106 -3.86% 9 2%
        Ag ppm 162 268 273.4 2.01% 9 6%
        Au ppm 190 8.98 8.98 0.01% 1 1%
      High Grade Cu % 190 0.176 0.182 3.48% 4 2%
      MAT12 Pb % 190 6.83 6.71 -1.81% 8 4%
        Zn % 190 6.95 6.97 0.26% 1 1%
        Ag ppm 243 13.8 14.21 2.94% 12 5%
        Au ppm 241 0.065 0.064 -0.79% 6 2%
      Low Grade Cu % 243 0.071 0.073 3.17% 18 7%
      PEPSSTD001 Pb % 243 0.406 0.406 0.10% 10 4%
        Zn % 243 1.02 1.02 -0.16% 3 1%
        Ag ppm 208 49.1 50.64 3.15% 9 4%
Aug. 2018 - May. 2019       Au ppm 207 0.239 0.238 -0.47% 1 0%
  ALS   Medium Grade Cu % 208 0.07 0.073 4.97% 2 1%
      PEPSSTD002 Pb % 208 1.48 1.483 0.21% 0 0%
        Zn % 208 3.14 3.15 0.20% 0 0%
        Ag ppm 99 243 239.1 -1.60% 8 8%
        Au ppm 99 2.358 2.316 -1.79% 1 1%
      High Grade Cu % 99 0.183 0.196 7.04% 5 5%
      PEPSSTD003 Pb % 99 5.79 5.71 -1.43% 4 4%
    AR Digestion - AAS   Zn % 99 7.34 7.44 1.43% 7 7%
        Ag ppm 225 23.3 24.72 6.11% 1 0%
        Au ppm 223 0.316 0.324 2.54% 10 4%
      Low Grade Cu % 225 0.054 0.057 5.17% 5 2%
      PEPSSTD004 Pb % 225 0.463 0.471 1.69% 1 0%
        Zn % 225 0.569 0.543 -4.51% 10 4%
        Ag ppm 228 40.76 41.79 2.53% 1 0%
        Au ppm 227 0.525 0.519 -1.12% 7 3%
      Medium Grade Cu % 228 0.055 0.056 2.01% 2 1%
      PEPSSTD005 Pb % 228 1.152 1.134 -1.60% 0 0%
        Zn % 228 1.515 1.536 1.41% 5 2%
        Ag ppm 21 185.1 185.14 0.02% 0 0%
        Au ppm 21 0.438 0.433 -1.12% 0 0%
      High Grade Cu % 21 0.186 0.188 0.84% 0 0%
      PEPSSTD006 Pb % 21 4.17 4.11 -1.52% 0 0%
        Zn % 21 6.63 6.86 3.43% 0 0%
        Ag oz/t 95 0.44 0.046 4.71% 1 1%
        Ag ppm 117 13.8 14.48 4.92% 1 1%
      Low Grade Cu % 212 0.071 0.074 4.94% 0 0%
      PEPSSTD001 Pb % 212 0.406 0.414 2.06% 2 1%
        Zn % 212 1.02 1.023 0.26% 0 0%
        Ag oz/t 109 1.58 1.54 -2.48% 0 0%
        Ag ppm 130 49.1 48.44 -1.34% 0 0%
  Inspectorate EP AR Digestion - AAS Medium Grade Cu % 239 0.07 0.074 6.13% 1 0%
      PEPSSTD002 Pb % 239 1.48 1.542 4.21% 2 1%
        Zn % 239 3.14 3.08 -1.86% 12 5%
        Ag oz/t 55 7.81 8.37 -5.61% 0 0%
        Ag ppm 188 243 231.58 -4.70% 0 0%
      High Grade Cu % 243 0.183 0.188 2.75% 1 0%
      PEPSSTD003 Pb % 243 5.79 5.64 -2.67% 4 2%
        Zn % 243 7.34 7.35 0.13% 18 7%
        Ag ppm 83 13.8 14.48 4.91% 0 0%
      Low Grade Cu % 83 0.071 0.074 4.35% 0 0%
      PEPSSTD001 Pb % 83 0.406 0.415 2.11% 0 0%
        Zn % 83 1.02 1.018 -0.24% 1 1%
        Ag ppm 70 49.1 48.17 -1.89% 0 0%
      Medium Grade Cu % 70 0.07 0.073 4.69% 1 1%
      PEPSSTD002 Pb % 70 1.48 1.542 4.17% 1 1%
        Zn % 70 3.14 3.07 -2.09% 0 0%
        Ag ppm 77 243 229 -5.76% 0 0%
      High Grade Cu % 77 0.183 0.188 2.77% 0 0%
      PEPSSTD003 Pb % 77 5.79 5.58 -3.59% 0 0%
        Zn % 77 7.34 7.33 -0.08% 0 0%
  Inspectorate EP AR Digestion - AAS   Ag ppm 58 23.3 24.24 4.05% 1 2%
      Low Grade Cu % 58 0.054 0.057 4.82% 2 3%
      PEPSSTD004 Pb % 58 0.463 0.454 -1.90% 0 0%
        Zn % 58 0.569 0.574 0.96% 0 0%
        Ag ppm 50 40.76 40.38 -0.94% 1 2%
      Medium Grade Cu % 50 0.055 0.057 3.31% 1 2%
      PEPSSTD005 Pb % 50 1.152 1.203 4.41% 1 2%
        Zn % 50 1.515 1.558 2.83% 0 0%
        Ag ppm 60 185.1 181.81 -1.78% 1 2%
      High Grade Cu % 60 0.186 0.185 -0.50% 0 0%
      PEPSSTD006 Pb % 60 4.17 4.21 1.05% 0 0%
        Zn % 60 6.63 6.66 0.48% 1 2%
        Ag ppm 308 13.8 14.19 2.84% 1 0%
        Au ppm 307 0.065 0.065 -0.28% 6 2%
      Low Grade Cu % 308 0.071 0.073 3.46% 0 0%
      PEPSSTD001 Pb % 308 0.406 0.407 0.18% 1 0%
        Zn % 308 1.02 1.03 -0.91% 3 1%

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Period

Laboratory

Analytical Method

Type Standard

Element

No. Samples

Best Value

Mean

Bias

No. Samples Outside 3SD

Failure Rate

        Ag ppm 305 49.1 50.65 3.16% 1 0%
        Au ppm 304 0.239 0.239 -0.16% 8 3%
      Medium Grade Cu % 305 0.07 0.074 5.90% 2 1%
      PEPSSTD002 Pb % 305 1.48 1.481 0.06% 0 0%
        Zn % 305 3.14 3.12 -0.56% 0 0%
        Ag ppm 77 243 239.83 -1.30% 1 1%
        Au ppm 77 2.358 2.338 -0.84% 1 1%
      High Grade Cu % 77 0.183 0.195 6.62% 1 1%
      PEPSSTD003 Pb % 77 5.79 5.71 -1.45% 2 3%
        Zn % 77 7.34 7.49 2.09% 1 1%
  ALS AR Digestion - AAS   Ag ppm 706 23.3 24.72 6.10% 7 1%
        Au ppm 703 0.316 0.327 3.42% 10 1%
      Low Grade Cu % 706 0.054 0.057 4.81% 0 0%
      PEPSSTD004 Pb % 706 0.463 0.466 0.63% 5 1%
        Zn % 706 0.569 0.544 -4.39% 7 1%
        Ag ppm 734 40.76 41.97 2.98% 9 1%
        Au ppm 733 0.525 0.531 1.23% 7 1%
      Medium Grade Cu % 734 0.055 0.057 2.77% 8 1%
      PEPSSTD005 Pb % 734 1.152 1.134 -1.61% 7 1%
        Zn % 734 1.515 1.534 1.27% 4 1%
        Ag ppm 195 185.1 186.17 0.58% 2 1%
        Au ppm 195 0.438 0.44 0.45% 1 1%
      High Grade Cu % 195 0.186 0.19 1.93% 0 0%
      PEPSSTD006 Pb % 195 4.17 4.11 -1.32% 2 1%
        Zn % 195 6.63 6.88 3.82% 2 1%

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Figure 8-3:             CRMs PEPSSTD001 and PEPSSTD002 Results for Zinc –Inspectorate EP (2018 to 2019) 

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Figure 8-4:               CRMs PEPSSTD002 and PEPSSTD003 Results for Lead –Inspectorate EP (2018 to 2019)

 

SLR reviewed the results returned from the CRMs and notes that Nexa has implemented procedures reducing the CRM failure rates significantly. Results for the CRMs are generally within acceptable limits with a small percentage of failures.

 

In the SLR QP’s opinion, the CRMs cover a reasonable range of grades with respect to the overall resource grades and no significant bias was observed.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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8.3.3 Blanks

 

The regular submission of blank material is used to assess contamination during sample preparation and to identify sample numbering errors. Field blank samples are composed of barren material that have grades that are less than the detection limits.

 

8.3.3.1 Milpo, 2014 to 2017

 

A total of 1,800 blanks with 30,370 drill hole samples and a total of 785 blanks with 10,213 channel samples (a submission rate of 1 in 13 samples) were sent to Inspectorate.

 

The results in all the laboratories show a pass rate greater than 99% indicating negligible contamination.

 

8.3.3.2 Nexa, November 2017 to 2020

 

Since 2018, a total of 3,821 coarse blanks (2.3%) and 2,600 fine blanks (1.6%) were inserted with core samples. These indicated no significant contamination occurred during the preparation and analysis of the samples. Table 8-8 and Table 8-9 present the results of the coarse and fine blanks, respectively. Results of the blanks are illustrated in Figure 8-5 with Nexa’s tolerance limit set at approximately five times the detection limits.

 

 

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Table 8-8:           2017 to 2020 Fine Blank Results 

Nexa Resources S.A. – El Porvenir Mine

 

Period

Laboratory

QA/QC Samples

Type

No.
Samples

Failure Limit
%

Failure Rate (%)

Au ppm

Ag oz/t

Ag ppm

Cu %

Pb %

Zn %

Nov. 2017 – Aug. 2018 Certimin Blanks Fine 617 <5% 0.00% 0.20% - 0.00% 0.20% 0.20%
  Inspectorate EP Blanks Fine 342 <5% 0.00% 0.00% - 0.00% 0.30% 0.00%
Aug. 2018 – May. 2019 Certimin Blanks Fine 321 <5% 0.00% 0.00% 0.00% 1.00% 0.00% 0.00%
  Inspectorate EP Blanks Fine 361 <5% 0.00% 0.00% - 0.00% 0.00% 0.00%
  ALS Blanks Fine 959 <5% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00%

 

Table 8-9: 2017 to 2020 Coarse Blank Results 

Nexa Resources S.A. – El Porvenir Mine

 

Period 

Laboratory

QA/QC Samples

Type

No.
Samples

Failure Limit %

Failure Rate (%) 

Au ppm

Ag oz/t

Ag ppm

Cu %

Pb %

Zn %

Nov. 2017 – Aug. 2018 Certimin Blanks Coarse 614 <5% 0.00% 0.00% - 0.00% 0.00% 0.00%
  Inspectorate EP Blanks Coarse 342 <5% 0.00% 0.30% - 0.00% 0.00% 0.00%
Aug. 2018 – May. 2019 Certimin Blanks Coarse 323 <5% 0.00% 0.00% 0.00% 1.00% 0.00% 0.00%
  Inspectorate EP Blanks Coarse 359 <5% - 0.00% 0.00% 0.00% 0.00% 0.00%
  ALS Blanks Coarse 956 <5% 0.00% 0.00% 0.00% 0.00% 0.00% 0.15%
Jun. 2019 – Feb. 2020 Inspectorate EP Blanks Coarse 181 <5% - - 0.00% 0.00% 0.00% 0.00%
  ALS Blanks Coarse 1046 <5% 0.00% - 0.00% 0.00% 0.00% 0.15%

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Figure 8-5:               2017 to 2020 Porvenir Blank Zn and Pb Assays – Inspectorate EP Laboratory

 

8.3.4 Duplicates

 

Duplicates help assess the natural local-scale grade variance or nugget effect and are also useful for detecting sample numbering mix-ups. The field (core) duplicates help monitor the grade variability as a function of both sample homogeneity and laboratory error.

 

The precision of sampling and analytical results can be quantified by re-analyzing the same sample using the same methodology. The variance between the measured results will measure their precision. Precision is affected by mineralogical factors such as grain size, distribution, and inconsistencies in the sample preparation and analysis processes. There are several different duplicate sample types, which can be used to determine the precision of the entire sampling, sample preparation, and analytical process. Blind duplicate samples are submitted to the laboratory. A description of the different types of duplicates used by El Porvenir is provided in Table 8-10.

 

 

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Table 8-10: Duplicate Types and Descriptions 

Nexa Resources S.A. – El Porvenir Mine

 

Duplicate

Description

Field The sample generated by another sampling operation at the same collection point includes a duplicate sample taken from a quarter of the drill core sample. Since mid-2016, a duplicate sample was taken from the second half of the drill core sample.
Reject The second sample obtained from splitting the coarse crushed rock during sample preparation and submitted blind to the same laboratory that assayed the original sample.
Pulp The second sample obtained from splitting the pulverized material during sample preparation and submitted blind at a later date to the same laboratory that assayed the original pulp.

 

Numerous plots and graphs are used monthly to monitor precision and bias levels. A brief description of the plots employed in the analysis of El Porvenir duplicate data is provided below:

 

Scatter plot: assesses the scattering degree of the duplicate result plotted against the original value, which allows for bias characterization and regression calculations.

Ranked half absolute relative difference (HARD) of samples plotted against their rank % value.

 

HARD:

 

Acceptable HARD value for field duplicates is < 30%

Acceptable HARD value for coarse duplicate is < 20%

Acceptable HARD value for pulp is < 10 %

 

Duplicates were submitted with channel samples and drill core samples. If both the original and duplicate results returned a value less than two times the detection limit, the results were disregarded for the HARD analysis due to distortion in the precision levels at very low grades.

 

8.3.4.1 Milpo, 2014 to 2017

 

This section has mostly been taken from SRK (2017).

 

SRK performed the HARD analysis for the elements Ag, Pb, Zn and Cu, which have the following detection limits: 0.13 oz Ag, 0.01% Pb, 0.01% Zn and 0.01% Cu. In this analysis, SRK filtered all the samples with grades below two times the detection limit. El Porvenir inserted field duplicates with drill core samples and channel samples as part of its QA/QC program.

 

Precision levels of core drill sample for field duplicate were found to be outside of the acceptable limits. Additionally, reject assay results were poor for both lead and zinc and the duplicate assay results for lead were outside of acceptable limits. The poor precision levels for the field duplicates have been attributed to the sampling procedures, specifically that Milpo did not mark the cut line on the core before the cutting phase or sending a quarter of the core for analysis as a field duplicate. Precision levels for field duplicates in the channel samples were also outside the acceptable limit, and reject assay results were poor for both silver and lead. Duplicate assay results for copper were slightly out of acceptable limits.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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8.3.4.2 Nexa, November 2017 to 2020

 

Duplicate control charts were prepared for Zn, Au, Ag, Cu, and Pb in both laboratories. A total of 4,685 pulp duplicates (2.8%), 3,640 coarse duplicates (2.2%), and 3,244 field duplicates (2%) were inserted. Overall, the duplicate results indicate relatively good assay precision, with the exception of zinc field duplicates due to the variability that is inherent in the samples. Table 8-11 presents the results of the duplicate samples analyzed and Figure 8-6 to Figure 8-8 present the field, reject, and pulp duplicate scatter plots for lead and zinc, respectively.

 

SLR recommends continuing to select duplicates that are representative of the mineralization Zn, Pb, Cu, and Ag grade ranges, and completing ongoing studies to investigate the component of variability that is inherent in the sample, versus the component due to assay precision.

 

 

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Table 8-11:              2017 to 2020 Porvenir Duplicate Performance 

Nexa Resources S.A. – El Porvenir Mine

 

Period

Laboratory

QA/QC Samples

Type

No.
Samples

Failure Limit %

Bias (%) / Failure Rate (%)

Au ppm

Ag oz/t

Ag ppm

Cu %

Pb %

Zn %

      Twin sample 616 <30% 4.90% 9.60% - 5.50% 10.60% 14.00%
  Certimin Duplicates Coarse 612 <20% 0.80% 0.80% - 0.70% 10.60% 0.30%
Nov. 2017 – Aug. 2018     Pulps 612 <10% 1.30% 1.50% - 0.00% 0.20% 0.00%
      Twin sample 340 <30% - 3.80% - 2.90% 7.60% 11.50%
  Inspectorate EP Duplicates Coarse 340 <20% - 0.30% - 0.00% 7.60% 0.90%
      Pulps 339 <10% - 0.60% - 0.90% 1.20% 1.50%
      Twin sample 322 <30% 0.31% 1.49% 0.75% 2.17% 1.55% 3.11%
  Certimin Duplicates Coarse 330 <20% 0.30% 0.00% 0.00% 0.00% 0.00% 0.00%
      Pulps 335 <10% 0.60% 0.00% 0.00% 0.00% 0.00% 0.00%
      Twin sample 193 <30% - 5.47% 4.55% 3.11% 11.92% 11.40%
Aug. 2018 – May. 2019 Inspectorate EP Duplicates Coarse 357 <20% - 0.00% 0.00% 0.00% 0.00% 0.00%
      Pulps 340 <10%   0.00% 0.40% 0.52% 0.52% 1.04%
      Twin sample 943 <30% 0.95% 2.86% 1.87% 2.33% 3.29% 6.79%
  ALS Duplicates Coarse 965 <20% 0.10% 0.00% 0.32% 0.10% 0.00% 0.21%
      Pulps 1012 <10% 0.99% 0.00% 0.31% 0.30% 0.10% 0.20%
      Twin sample 23 <30% - - 0.00% 4.35% 21.74% 30.43%
  Inspectorate EP Duplicates Coarse 182 <20% - - 0.00% 0.00% 0.00% 1.10%
Jun. 2019 – Feb. 2020     Pulps 282 <10%   - 0.71% 0% 0.35% 0.71%
      Twin sample 807 <30% 1.24% - 2.97% 2.60% 4.83% 5.33%
  ALS Duplicates Coarse 854 <20% 0.12% - 0.00% 0.12% 0.12% 0.00%
      Pulps 1765 <10% 0.62% - 0.57% 0.28% 0.34% 0.45%

 

 

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Figure 8-6:              2017 to 2020 Porvenir Field Duplicates for Zn and Pb Assays – Inspectorate EP Laboratory

 

 

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Figure 8-7:               2017 to 2020 Porvenir Coarse Reject Duplicates for Zn and Pb Assays – Inspectorate EP Laboratory 

 

 

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Figure 8-8:               2017 to 2020 Porvenir Pulp Duplicates for Zn and Pb Assays – Inspectorate EP Laboratory

 

8.3.5 External Check Samples

 

Submitting assays to a secondary laboratory helps to monitor bias at the principal laboratory. Reference materials and blanks were inserted in the check assay batches.

 

An example of zinc and lead assay performance for the check assays is provided in Figure 8-9.

 

 

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Nexa sent 1,776 pulp samples analyzed at Inspectorate EP to ALS and analyzed at ALS to Certimin for referee check assays. An approximate insertion rate of 2.0 % is used for external check samples. Statistics for the check assay results are presented in Table 8-12.

 

Table 8-12:             2017 to 2020 Porvenir External Check Performance 

Nexa Resources S.A. – El Porvenir Mine

 

Period

Secondary
Laboratory

Primary
Laboratory

Element

No.
Samples

Bias
(%)

      Au ppm 432 -2.15
      Ag ppm 435 0.56
  Certimin ALS Cu per 435 -1.66
      Pb per 435 -1.10
      Zn per 435 -0.55
Nov. 2017 - Aug. 2018     Au ppm 202 -6.68
      Ag ppm 202 0.09
    Certimin Cu per 202 1.59
      Pb per 202 -0.35
  ALS   Zn per 202 2.37
      Ag ppm 110 4.63
    Inspectorate EP Cu per 110 2.25
      Pb per 110 0.63
      Zn per 110 3.3
      Au ppm 280 0.32
      Ag ppm 282 -1.42
  Certimin ALS Cu per 282 -1.86
      Pb per 282 -1.03
      Zn per 282 -4.02
Aug. 2018 - May. 2019     Au ppm 162 -0.26
    Certimin Ag ppm 162 -0.71
      Cu per 162 -1.75
  ALS   Pb per 162 -1.28
      Zn per 162 1.54
      Ag ppm 197 4.04
    Inspectorate EP Cu per 197 2.63
      Pb per 197 1.53
      Zn per 197 2.45

 

 

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Period

Secondary
Laboratory

Primary
Laboratory

Element

No.
Samples

Bias
(%)

      Au ppm 294 0.26
      Ag ppm 294 2.90
  Certimin ALS Cu per 294 -1.80
      Pb per 294 1.76
Jun. 2019 - Feb. 2020     Zn per 294 -1.47
      Ag ppm 94 2.23
  ALS Inspectorate EP Cu per 94 3.44
      Pb per 94 1.52
      Zn per 94 4.06

 

 

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Figure 8-9:              2017 to 2020 Porvenir External Checks for Zn and Pb Assays – Inspectorate EP Laboratory

 

The check assay results compared well, showing very high overall correlation coefficients. For silver, a potential positive of approximately 5% at Inspectorate EP in comparison to ALS was observed and should be investigated.

 

The SLR QP is of the opinion that the Inspectorate EP laboratory zinc, lead, copper, and silver assays are reliable and meet industry standards.

 

 

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8.4 QA/QC Recommendations

 

SLR’s QA/QC recommendations are as follows:

 

Revaluate the 2014 to 2017 QA/QC failure rates after removing CRM numbering mix-ups and adjusting the failure limits for certain CRMs.

 

Investigate the potential 5% positive silver bias at Inspectorate EP.

 

In the SLR QP’s opinion, the QA/QC program as designed and implemented by El Porvenir is adequate, and the assay results within the database are suitable for use in a Mineral Resource estimate.

 

8.5 Data Management

 

Database management is performed by a dedicated on-site geologist under the supervision of the Resource Geologist. Data is stored centrally on a Microsoft Cloud server in Fusion, a Datamine database product. Previous 2017, digital logging sheets prepared by the geologist were uploaded to the database management system Scoret (Balanza), which has now been superseded by Fusion. Original drill logs, structural logs, geotechnical logs, and details related to the holes are stored on-site in a folder, specific to each drill hole. Folders are clearly labelled and stored in a cabinet in the office.

 

Assay certificates are mailed to the Mine by ALS Peru S.A and Inspectorate and emailed to Nexa’s mine and corporate Database Administrators. Certificates are reviewed by the Mine Database Administrator prior to uploading information to Fusion.

 

Access to the El Porvenir database is by registered Fusion users from Nexa. Nexa maintains several user profiles with different access permissions and privileges defined by the Database Administrator. The data is updated automatically daily and weekly. Monthly back-ups are run following Nexa protocols.

 

8.6 Sample Security

 

Core boxes were transported every day to the core shed by personnel from the drilling company. Samples were transported by a contractor supervised by the company personnel. Core boxes and samples were stored in safe, controlled areas.

 

Chain-of-custody procedures were followed whenever samples were moved between locations and to and from the laboratory, by the filling out of sample submittal forms.

 

In the SLR QP’s opinion, the sample preparation, analysis, and security procedures at El Porvenir are adequate for use in the estimation of Mineral Resources.

 

In the SLR QP’s opinion, the QA/QC program as designed and implemented by Nexa is adequate and the assay results within the database are suitable for use in a Mineral Resource estimate.

 

 

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9.0 Data Verification

 

9.1 Databases and Internal Verification

 

During the last quarter of 2017, Nexa transferred the database from SIOM database management system and Excel files to Fusion software and prepared an exhaustive number of checks to confirm the accuracy of the data migration. Nexa has implemented a series of routine verifications to ensure the collection of reliable data. Logging and sampling data are digitally entered into the database by downloading the information from the logging tablets.

 

Core logging, surveying, and sampling were monitored by exploration and mine geologists and verified routinely for consistency. The El Porvenir resource database is regularly maintained and validated by the database administrator using Fusion software validation routines and by regularly checking the drill hole data on-screen visually. Personnel from the Geology department conduct daily quality control checks on the data entry. A first check consists of identifying duplicate sample numbers or lack of information for certain intervals. Every month, all the assay data entered in the server are compared with a compilation of individual CSV files issued by the laboratory. Paper records are stored at a safe location at the Mine.

 

Assay data are captured from the Global LIMS server using custom routines, and this information is then entered into the Fusion database. The laboratory also issues CSV and pdf-format certificates, however, only the information that is digitally captured from the server is considered to be the true record.

 

Nexa prepared “The Informe de Validación de Base de Datos Atacocha” report containing additional detail regarding the data validation for El Porvenir (Nexa, 2019c). During this validation, Nexa found 76 channels and one drill hole creating inconsistencies with surrounding data. As a result, these channels and hole were removed from the Mineral Resource database.

 

The SLR QP is of the opinion that the data collection, import, and validation workflows are consistent with industry standards, and are of sufficient quality to support Mineral Reserve and Mineral Resource estimation.

 

9.2 Previous Verification

 

In 2017, Amec Foster Wheeler (Amec) audited the Atacocha database (which also includes El Porvenir). Amec reviewed and validated the information from 2011 to 2017 compiled by Nexa. Amec used signed assay certificates to verify the assays in the database; some inconsistencies were observed in Zn and Cu assays. Other checks included collar locations, downhole survey measurements, and lithology codes. Some inconsistencies were observed. In addition, a comparison between drill hole assay and channel assay was performed. The test compared results of nearby holes by searching for channel samples near drill holes within a four-metre distance. Amec constructed QQ plots and found that both grade distributions were very similar, with no bias observed (Amec, 2017).

 

As part of SRK’s 2017 NI 43-101 Technical Report, SRK performed assay data verification by comparing assay certificates with values in the database. SRK found that a significant number of historical samples did not have assay certificates and downgraded some areas to Inferred as a result. Nexa has found more assay certificates since 2017 and completed a statistical and visual study that concluded that there were no significant issues with the historical data. SLR reviewed Nexa’s comparison work and concurred with the inclusion of historical data in the resource estimate with no classification downgrade.  

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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9.3 SLR Verification

 

SLR visited El Porvenir from September 5 to 7, 2018. During the site visit, SLR reviewed plans and sections, visited the core shack, examined some drill cores and mineralization exposures at the underground mine, and held discussions with Nexa personnel.

 

As part of the data verification process, SLR inspected the drill holes in section and plan view to review geological interpretation related to drill hole and channel database and found good correlation. SLR queried the database for unique headers, unique samples, duplicate holes, overlapping intervals, blank and zero grade assays, and long interval sample, and reviewed QA/QC data collected by Nexa. SLR did not identify any significant discrepancies.

 

9.3.1 Assay Certificate Verification

 

SLR performed checks on the El Porvenir Mineral Resource database by converting approximately 166,000 assay certificate results spanning August 2011 to March 2020 from original PDF and Excel formats to reformatted comma delimited text (CSV) files, compiled and imported them to a database, and then compared the compiled certificate assays to the assay table in the Mineral Resource drill and sample database. The work matched approximately 53,000 sample IDs to the assay database for Zn, Cu, Pb, Ag, and Fe. Results of the exercise are shown in Table 9-1. No significant errors were found. There were 629 samples for Ag where the values in the database ranged from 25 g/t Ag to 285 g/t Ag lower than the certificate assays. This is likely a result of choosing the lower value of multiple re-assays and shows a conservative approach since all mis-matched values were lower in the Mineral Resource database, and SLR did not include the results of a re-assay program in its certificate conversion and compilation exercise.

 

Table 9-1:            SLR Assay Certificate Verification Results 

Nexa Resources S.A. – El Porvenir Mine

 

Element   Assays
Count
  Count
Certificate
IDs
  Certificates
Start
  Certificates
End
  % of
Assays
in DB
  Sample
ID
Matches
  Abs. Diff.
Threshold
  Num
Outside
Threshold
  Notes
ZN (%)   763,041   165,681   2011-07-03   2019-10-30   22%   52,860   1   0    
CU (%)   736,580   165,622   2012-04-08   2019-10-30   22%   52,860   0.001   2   Both samples 1.5 vs DHDB 1.0
PB (%)   760,687   165,668   2011-07-03   2019-10-30   22%   52,860   1   0    
AG (PPM)   764,211   165,626   2011-07-03   2019-10-30   22%   52,860   25   629   all Certimin, all DHDB samples lower grade than certificates – likely due to resample program
FE (%)   229,134   165,262   2011-07-03   2019-10-30   72%   52,860   1   0    

 

 

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SLR did not review the pre-2011 certificate data as it is mostly located in mined-out areas. The bulk of the Mineral Resources and Mineral Reserves are supported with data from 2011 to 2020. Figure 9-1 shows the distribution of pre-2011 (green) and 2011-2020 (red) assays for zinc in the Mineral Resource and Mineral Reserve area. Unsampled drill traces are grey. Note the Mineral Resource and Mineral Reserve solids are well-covered by the 2011-2020 sampling. Assay certificates pre-2011 were not available, with exception of 2009, however, Nexa and SLR reviewed this data in sections and plan views. Overall, the data compared well with recent drilling. Based on SLR’s review, there is no reason to believe there is any significant issue related to this data, furthermore, Nexa is currently drilling in these areas to confirm assay values.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Figure 9-1:                Assay Sampling Coverage (Zn)

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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9.3.2 Density Verification

 

SLR converted 3,553 density measurement certificates, spanning November 2015 to February 2020, from original Excel formats to reformatted CSV text files, compiled and imported them to a database, and compared them to the density table in the Mineral Resource drill and sample database.

 

Four files from 2011, 2012 and 2014 appear to contain grab samples, and only two of these had sample ID fields which concatenated the index and year in the table. Spot checks of the available sample IDs against the density table in the Mineral Resource database resulted in zero matches.

 

There were 565 certificate ID matches out of 1,131 in the El Porvenir Mineral Resource database, resulting in a comparison rate of 50%. SLR notes that there was only one density discrepancy greater than 0.2 g/cm3 between the matching certificate and the Mineral Resource sampleIDs. SLR considers this to be a very good result. Spatial coverage of the density samples relative to Mineral Resources (blue) and Mineral Reserves (orange) are shown in Figure 9-2.

 

The SLR QP found that the database is well maintained, and generally exceeds industry standards. The SLR QP is of the opinion that database and database verification procedures for El Porvenir comply with industry standards and are adequate for the purposes of Mineral Resource estimation.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Figure 9-2:                Density Sampling Coverage

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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10.0 Mineral Processing and Metallurgical Testing

 

10.1 Test Work

 

Nexa began developing a geometallurgical model for El Porvenir in 2017. The objectives of the work were to develop a geometallurgical model able to predict the recovery of lead, zinc, copper, arsenic, and manganese, concentrate grades, as well as abrasiveness (abrasion index (Ai)) and hardness (Bond ball mill work index (BWi)), and therefore throughput based on ore source within the deposit. The aim of the development work included:

 

Maximization of operational value of the El Porvenir mining unit.

 

Reduction of risks to production related to:

 

Plant throughput.

 

Grinding media consumption.

 

Recovery of valuable minerals.

 

Concentrate quality.

 

Identification of flaws in the quality and interpretation of the available information.

 

Identification of opportunities for improvement and to reduce risk.

 

Definition and validation of geometallurgical domains from metallurgical test results.

 

Evaluation of contaminants in the deposit.

 

The geometallurgical sample selection and test work were planned with the assistance of Transmin Metallurgical Consultants (Transmin). Preliminary results and interpretation were reported by Transmin in the report Estudio Geometalurgico Preliminar para Unidad Minera El Porvenir, June 15, 2018 (Transmin, 2018). The preliminary work was followed up by two additional phases of test work reported in Estudio Geometalúrgico Fase 2 para Unidad Minera El Porvenir, April 29, 2019 (Transmin, 2019) and Estudio Geometalúrgico Fase 3 para Unidad Minera El Porvenir, May 18, 2020 (Transmin, 2020).

 

In 2017, fifteen samples from El Porvenir were submitted for metallurgical testing. The samples were intended to be representative of 2018 concentrator feed. Test work included mineralogy, comminution testing (BWi and Ai), and flotation (variability tests, locked cycle tests (LCTs), and grind size evaluation).

 

Priority was given to samples from holes drilled in 2016 and 2017, so as to use the freshest possible material for metallurgical test work. Samples were selected to represent areas in the block model with Net Smelter Return (NSR) values greater than or equal to $40.94/t, as well as to include majority lithologies to be processed in 2018 (predominantly skarn and limestone). Grades of zinc, lead, copper, and silver were also considered in the selection of samples. Mineralogical characterization of the samples is represented in Figure 10-1 and Figure 10-2. The mineralogy is notable for the wide range of sulphide and sulphate content, the presence of sphalerite with manganese inclusions, as well as high levels of manganese sulphide in two samples, PAS-09 and PAS-23.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Source: Transmin, 2018

 

Figure 10-1:                 Bulk Mineralogical Analysis

 

 

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Source: Transmin, 2018

 

Figure 10-2:              Sulphide Mineral Breakdown

 

Comminution test results ranged from 0.04 g to 0.33 g for Ai and 7.3 kWh/t to 20.6 kWh/t for Bwi.

 

Three composite samples were produced for use in grind size optimization flotation tests and for LCTs. Two composites of plant feed representing October 2017 and November 2017 were collected for repeatability testing and cleaner regrind testing. Bulk rougher flotation was completed at three grind sizes, 80% passing (P80) 100 µm, 150 µm, and 200 µm. The tests indicated that there was a tendency towards higher recoveries of copper and zinc to the bulk rougher concentrate at the finer grind sizes. This would result, however, in the need for more effort to reject the additional zinc from the bulk concentrate. Recovery of lead to the bulk concentrate was less affected but improved at finer grind sizes. Therefore, it was noted that optimization of primary grind size could help to maximize recoveries of valuable minerals and metals, but primary grind size should be considered in conjunction with throughput and energy consumption.

 

An evaluation of regrind size was conducted by completing cleaner tests on bulk and zinc rougher concentrates at P80 20 µm and 40 µm, as well as without regrinding. The tests indicated that recoveries were lower at finer grind sizes, but also that grades at the finer grind sizes were higher. It was noted that optimization of regrind size could help to reduce energy consumption for regrinding, while still achieving target concentrate grades.

 

A LCT was completed which produced a bulk concentrate of 53.8% Pb and zinc concentrate of 52.7% Zn. The limit for bismuth in the lead concentrate (1,000 ppm Bi) was exceeded at 5,597 ppm Bi, and the limit for cadmium in the zinc concentrate (3,000 ppm Cd) was exceeded at 3,275 ppm Cd. Final recoveries for lead and zinc were 88.2% and 91.5%, respectively.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Variability tests were completed on the 15 variability samples. The tests consisted of bulk and zinc rougher flotation conditions that were adjusted according to the lead and zinc content of the samples, resulting in five different sets of flotation conditions.

 

Lead recovery to the bulk concentrate averaged 92% (excluding the low lead content samples), while zinc recovery to the zinc rougher concentrate averaged 79%.

 

Test work results from the samples were used to derive recovery versus head grade relationships for lead, zinc, copper, manganese, and arsenic. Transmin noted that the number of samples tested was less than the number required to represent the variability of the deposit, and that additional test work would be required to validate and update the geometallurgical model. In addition, it was recommended that arsenopyrite and manganese sulphides be included in the logging of drill core samples, and that the behaviours of bismuth and antimony should be evaluated in future test work.

 

In Phase 2 of the geometallurgical model development, 96 samples were selected for metallurgical test work, including samples from both El Porvenir and Atacocha. Samples were selected to represent the distribution of ore (from different zones within the mines) planned to be mined in 2019 (except for Atacocha where sample material for certain zones to be mined in 2019 was not available), and from blocks in the block model with NSR values greater than or equal to $40.94/t.

 

Samples that underwent comminution testing included 36 samples from El Porvenir and 10 samples from Atacocha. Ai values of the samples ranged from 0.0056 g to 0.47 g, with the majority of samples in the low abrasiveness range of < 0.3 g. BWi for the samples ranged from 5.6 kWh/t to 20.7 kWh/t with the majority of samples in the medium to hard range of 9 kWh/t to 20 kWh/t. Abrasiveness and hardness were found to be related to the SiO2 content of the samples.

 

Flotation test work was completed on 45 variability samples (rougher tests) and a composite produced from 40 individual samples from El Porvenir and 10 individual samples from a blend of 75% El Porvenir and 25% Atacocha material. Three composites (two El Porvenir and one Atacocha) were submitted for mineralogical analysis. The main gangue minerals in the composites were silicates and carbonates and the main sulphide minerals were pyrite, sphalerite, and galena. The flotation test work indicated that lead recovery was related to the lead head grade, and silver recovery was related to lead recovery; zinc, manganese, and arsenic recoveries were noted to be related to the source zone of the samples. LCTs conducted on the composites did not achieve stability and were therefore not included in the analysis of results.

 

In Phase 3 of the geometallurgical model development, 46 additional samples representing different zones and lithologies at El Porvenir underwent comminution testing. Ai results ranged from 0.0030 g to 0.68 g and BWi results ranged from 5.67 kWh/t to 23.1 kWh/t. Abrasiveness was found to be related to ore zone, lithology, SiO2 content, and loss on ignition (LOI). BWi was found to be related to ore zone, lithology, and SiO2 content.

 

A further 29 samples were used to produce two composites representing ore to be mined from 2020 to 2022, as well as three samples used to produce a composite representing the Don Ernesto zone for flotation test work. Mineralogical analysis of the composites indicated that the main sulphide minerals were pyrite, sphalerite, pyrrhotite, and galena. Compared to the 2020 to 2022 composites (PDFC-01 and PDFC-02), the Don Ernesto composite (PDFC-03) was higher in sulphides and also contained 2.5% bournonite (PbCuSbS3), while PDFC-02 contained 2.1% alabandite (MnS). Gangue minerals were mainly silicates and carbonates.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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LCTs were completed on PDFC-01 and PDFC-02 to produce bulk copper-lead concentrates and zinc concentrates. These tests produced the following results:

 

PDFC-01

 

The bulk concentrate achieved a grade of 6.1% Cu, 41.7% Pb, and 2,623 g/t Ag at recoveries of 50.3% Cu, 91.7% Pb, and 73.6% Ag.

 

The zinc concentrate achieved a grade of 49.7% Zn at a recovery of 91%.

 

The bulk concentrate was consisted mainly of galena (47%), chalcopyrite (16%), and sphalerite (15%, mostly associated with galena).

 

The zinc concentrate consisted mainly of sphalerite (85%).

 

PDFC-02

 

The bulk concentrate reached a grade of 1.0% Cu, 42.4% Pb, and 2.808 g/t Ag at recoveries of 34% Cu, 87% Pb, and 70% Ag. It also contained 8% Mn and 11% Zn.

 

The Zn concentrate reached a grade of 41.8% Zn at a recovery of 73%.

 

The bulk concentrate consisted of galena (44%), alabandite (13%), and sphalerite (21%). Sphalerite was associated equally with galena and pyrite.

 

The zinc concentrate consisted mainly of sphalerite (70%) and 5% alabandite.

 

Transmin recommended that manganese sulphides, lead oxides, and whole rock analysis, particularly for SiO2, be included in drill core analysis, that manganese be included in the geological model, and that consideration be given to mapping high SiO2 zones.

 

Based on the results of the test work, Transmin produced relationships for comminution parameters (Ai and BWi) and flotation predictions for recoveries and grades for copper, lead, and zinc concentrates using ore zones and grades that could be used in geometallurgical modelling. These relationships were updated through the various phases of test work.

 

10.2 Operational Performance

 

Key operational performance figures for the El Porvenir concentrator since the beginning of 2016 are presented in Table 10-1. With zinc head grades of approximately 2.9% Zn and lead head grades of approximately 1.0% Pb, as well as high zinc recoveries (88%) and slightly lower lead recoveries (79%) to the respective concentrates, El Porvenir zinc concentrate production in 2019 was 110,000 t, while lead concentrate production was 33,000 t. Low copper head grades and low copper recovery to copper concentrate results in only minor copper concentrate production. Gold head grades are low at approximately 0.5 g/t Au and combined gold recovery to the lead and copper concentrates is approximately 30%, resulting in low (less than 1 oz/t Au) payable levels of gold in both concentrates. Silver recovery to the lead concentrate of 57% results in payable silver values in the lead concentrate (approximately 2,500 g/t Ag in 2020). Although silver recovery to the copper concentrate is low (5.1% in 2020), silver content in the copper concentrate is high enough (approximately 2,800 g/t Ag in 2020) that it likely contributes to the salability of the concentrate.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Production in 2020 was significantly lower than in 2019 due to the effects of the COVID-19 pandemic and associated production interruptions. On March 15, 2020, the Peruvian Government declared a national emergency and imposed operating business restrictions including on the mining sector. The quarantine period was initially expected to last until the end of March 2020 but was subsequently extended up to May 10, 2020. In light of the government restrictions, Nexa suspended production at El Porvenir. During this period, mining activities were limited to critical operations with a minimum workforce to ensure appropriate maintenance, safety, and security. On May 6, 2020, the Peruvian Government announced the conditions for the resumption of operations for different sectors, including mining operations above 5,000 tpd. As a result, El Porvenir operations, which were suspended on March 18, 2020, restarted production on May 11, 2020, following the end of the quarantine period. After the resumption of operations, El Porvenir ramped up production to pre-pandemic levels by June 2020.

 

Table 10-1:                 Concentrator Operational Performance 

Nexa Resources S.A. – El Porvenir Mine

 

    Units   Item   2016   2017   2018   2019   2020
Ore Processed   tonnes       2,154,151   1,834,511   2,149,927   2,120,765   1,502,618
Mill Head Grade   g/t   Ag   60.2   63.6   59.7   64.6   62.3
    %   Cu   0.14   0.13   0.15   0.15   0.17
    %   Pb   0.99   1.04   0.98   1.01   0.93
    %   Zn   3.22   2.86   3.04   2.93   2.65
Cu Concentrate   tonnes       2,949   2,460   2,701   2,185   1,711
    %   Cu Grade   22.2   20.0   21.0   21.3   19.5
    %   Cu Recovery   22.0   23.1   18.0   14.7   12.7
    oz/t   Ag Grade   102.6   85.4   55.4   81.3   89.9
    %   Ag Recovery (to Cu)   7.4   6.6   3.7   4.1   5.1
    oz/t   Au Grade   1.21   0.96   0.68   0.87    
    %   Au Recovery (to Cu)   10.7   9.2   5.8   5.0    
Pb Concentrate   tonnes       31,195   28,726   31,662   33,018   21,213
    %   Pb Grade   55.0   51.6   52.6   51.2   51.2
    %   Pb recovery   80.8   77.5   79.1   79.0   77.8
    oz/t   Ag Grade   77.3   74.8   75.3   78.4   80.7
    %   Ag Recovery (to Pb)   57.7   57.4   57.8   58.8   56.9
    oz/t   Au Grade   0.18   0.21   0.25   0.24    
    %   Au Recovery (to Pb)   16.3   21.4   24.7   25.5    
Zn Concentrate   tonnes       121,294   92,446   115,256   109,976   69,891
    %   Zn Recovery   90.2   87.9   88.7   88.2   87.7
    %   Zn Grade   51.6   49.9   50.2   49.7   49.9

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Historical monthly recoveries at El Porvenir for 2015 to 2020 are presented in Figure 10-3, which shows zinc, lead, and copper recoveries to their respective concentrates, and total silver and gold recoveries to the lead and copper concentrates.

 

 

Figure 10-3: Historical Recovery to Concentrate

 

10.3 Deleterious Elements

 

Bismuth levels in the copper concentrate will likely attract penalty charges, while arsenic may exceed penalizable levels from time to time. Zinc and lead contents in the copper concentrate are high (combined approximately 15% to 20%) and attract penalties, however, the high silver and gold content (2,529 g/t Ag and 27 g/t Au in 2019) likely help the saleability of the small volumes of copper concentrate produced. Currently the copper concentrate attracts penalties of approximately US$17/dmt.

 

The zinc and lead concentrates are clean and do not typically attract penalty charges, although the bismuth content of the lead concentrate could reach penalizable levels if there is a high content of bismuth in the ore.

 

In the SLR QP’s opinion, the metallurgical recovery data is adequate for the purposes of Mineral Resource and Mineral Reserve estimation in this Technical Report Summary.

 

 

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11.0 Mineral Resource Estimates

 

11.1 Summary

 

The Mineral Resource estimate for El Porvenir, dated December 31, 2020, using all data available as of February 15, 2020 was completed by El Porvenir staff (Nexa, 2020b) and reviewed by SLR.

 

The Mineral Resource estimate was completed using Datamine Studio RM and Leapfrog Geo software. Wireframes for geology and mineralization were constructed in Leapfrog Geo based on geology sections, assay results, lithological information, underground mapping, and structural data. Assays were capped to various levels based on exploratory data analysis and then composited to two metre lengths. Wireframes were filled with blocks and sub-celling at wireframe boundaries. Blocks were interpolated with grade using ordinary kriging (OK) and inverse distance cubed (ID3) interpolation algorithms. Block estimates were validated using industry standard validation techniques. Classification of blocks used distance-based and mineralization continuity criteria.

 

A summary of the El Porvenir Mineral Resources, exclusive of Mineral Reserves, is shown in Table 11-1. NSR cut-off values for the Mineral Resources were established using a zinc price of US$1.30 per pound, a lead price of US$1.02 per pound, a copper price of US$3.37 per pound, and a silver price of US$19.38 per ounce.

 

The Mineral Resources in El Porvenir are contained in four zones: Zona Alta (Upper Zone), Zona Intermedia (Intermediate Zone), Zona Baja (Lower Zone), and Profundizacion Zona (Mine Deepening Zone).

 

Mineral Resources at El Porvenir are reported using all the material within underground resource shapes generated in Deswik Stope Optimizer (DSO) software, satisfying minimum mining size, NSR cut-off values of US$60.06/t for the Upper Zone, US$61.09/t for the Intermediate Zone, US$59.75/t for the Lower Zone, and US$63.37/t for the Mine Deepening Zone for cut and fill (C&F) resource shapes, and continuity criteria.

 

SLR’s review of, and conclusions regarding, the resource model applies not just to the Mineral Resources listed in Table 11-1, but also to the Mineral Resources that were converted to Mineral Reserves.

 

The SLR QP reviewed the Mineral Resource assumptions, input parameters, geological interpretation, and block modelling and reporting procedures, and is of the opinion that the Mineral Resource estimate is appropriate for the style of mineralization at El Porvenir and that the block model is reasonable and acceptable to support the 2020 year end Mineral Resource estimate.

 

Mineral Resources have been classified in accordance with the definitions for Mineral Resources in S-K 1300, which are consistent with Canadian Institute of Mining, Metallurgy and Petroleum (CIM) Definition Standards for Mineral Resources and Mineral Reserves (CIM (2014) definitions).

 

 

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Table 11-1: El Porvenir Mineral Resources - December 31, 2020 

Nexa Resources S.A. – El Porvenir Mine

 

        Grade   Contained Metal
    Tonnage   Zinc   Lead   Copper   Silver   Zinc   Lead   Copper   Silver
Category   (Mt)   %   %   %   g/t   (000 t)   (000 t)   (000 t)   (000 oz)
Measured   0.23   2.59   0.99   0.23   63.46   6.0   2.3   0.5   471
Indicated   1.33   2.93   0.89   0.20   63.33   39.0   11.9   2.6   2,715
M+I   1.56   2.87   0.91   0.20   63.35   45.0   14.2   3.2   3,186
Inferred   8.47   3.60   0.95   0.23   78.37   305.0   80.8   19.8   21,345

 

Notes:

 

1. The definitions for Mineral Resources in S-K 1300 were followed for Mineral Resources which are consistent with CIM (2014) definitions.
2. Mineral Resources are reported on a 100% ownership basis. Nexa owns an 80.16% interest.
3. Mineral Resources are estimated at NSR cut-off values of US$60.06/t for the Upper Zone, US$61.09/t for the Intermediate Zone, US$59.75/t for the Lower Zone, and US$63.37/t for the Mine Deepening Zone for C&F resource shapes.
4. Mineral Resources are estimated using an average long term metal prices of Zn: US$2,869.14/t (US$1.30/lb); Pb: US$2,249.40/t (US$1.02/lb); Cu: US$7,426.59/t (US$3.37/lb); and Ag: US$19.38/oz, and metallurgical recoveries are based on recovery curves derived from historical processing data.
5. A minimum mining width of 4.0 m was used for C&F resource shapes.
6. Bulk density varies depending on mineralization domain.
7. Mineral Resources are exclusive of Mineral Reserves.
8. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability.
9. Numbers may not add due to rounding.

 

The SLR QP reviewed the Mineral Resource assumptions, input parameters, geological interpretation, and block modelling and reporting procedures, and is of the opinion that the Mineral Resource estimate is appropriate for the style of mineralization and that the block model is reasonable and acceptable to support the December 31, 2020 Mineral Resource estimate.

 

The SLR QP is of the opinion that, with consideration of the recommendations summarized in Section 1 and Section 23, any issues relating to all relevant technical and economic factors likely to influence the prospect of economic extraction can be resolved with further work.

 

11.2 Resource Database

 

Nexa maintains the entire database in Studio RM-Fusion. The resource database contains drilling information and analytical results up to February 15, 2020. Information received after this date was not used in the Mineral Resource estimate. The database comprises 4,643 drill holes for a total of 757,590.140 m and 17,127 underground channels for a total of 97,104.81 m.

 

The Mineral Resource estimate is based on the WGS-84 coordinate system, and two B-Level National Grid points are used as a reference for all topographical measurements.

 

SLR received data from Nexa in Microsoft Excel format. A Datamine database was also provided and extracted in CSV format. Data were amalgamated, parsed as required, and imported by SLR into Maptek’s Vulcan Version 10.1.5 (Vulcan) software and Sequent Limited’s Leapfrog software version 5.0 (Leapfrog) for review.

 

 

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The drill hole and channel database comprise coordinate, length, azimuth, dip, lithology, density, and assay data. For grade estimation, unsampled intervals within mineralization wireframes were replaced with half of the detection limit values. Detection limit text values (e.g., “<0.05”) were replaced with numerical values that were half of the analytical detection limit. The channel sample data was converted into drill hole data for use in interpretation and Mineral Resource estimation.

 

For the purpose of the Mineral Resource estimate, the drill hole data were limited to those assays located inside the mineralization wireframes. This includes 4,290 drill holes containing 38,158 samples totalling 54,463 m, and 10,069 underground channels containing 28,356 samples totalling 46,785 m. A total of 21 drill holes were excluded from the Mineral Resource database (Table 7-2) as they either overlapped with new holes and have discrepancies with these holes, or were relocated to the Atacocha (mine adjacent and connected by an underground drift with El Porvenir) database. These 21 holes were also excluded from the geological modelling and estimation processes. Figure 11-1 illustrates the drill hole location in relation with the mineralization solids.

 

 

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Technical Report Summary - January 15, 2021

 

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Figure 11-1: 3D View of El Porvenir Mineralized Solids and Drill holes

 

 

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The SLR QP conducted a number of checks on the Mineral Resource database as discussed in Section 9, Data Verification. The SLR QP is of the opinion that the database is of high quality and generally exceeds industry standards and is appropriate to support Mineral Resource estimation.

 

11.3 Geological Interpretation

 

The El Porvenir underground Mineral Resource estimate is based on assay and geological interpretation for each individual mineralized domain. Geological models were built by El Porvenir geologists using the drilling and channel sampling assay results, as well as geological domains such as: rock type (sandstone, calcareous breccia, marble and skarn), mineralization structure type (vein, orebody, and mantos), structural and lithological controls observed in underground workings and drill core logging data. Figure 11-2 and Figure 11-3 present the El Porvenir geological domains.

 

During the interpretation process, three main styles of mineralization were identified at the Porvenir deposit:

 

Skarn: mineralized zones of irregular to structurally controlled geometry, primarily contained within the Pucará Group, comprising garnet with associated metallic mineralization of galena, sphalerite, chalcopyrite, and silver-bearing sulphosalts (i.e., tetrahedrite).

 

Structurally controlled zones (i.e., veins): mineralization comprising galena, sphalerite, and silver-bearing sulphosalts (i.e., tetrahedrite) with quartz, rhodochrosite, and pyrite that forms structurally controlled shoots with lengths of up to 150 m and vertical extents of up to 350 m.

 

Replacement: lenses to irregular geometry contacts within the Pucará Group, comprising metallic mineralization of galena, sphalerite, chalcopyrite, and silver-bearing sulphosalts (i.e., tetrahedrite), and lenses or “mantos” in stratabound galena, sphalerite, and pyrite mineralization hosted in the Goyllarisquizga sandstone.

 

Skarn bodies are highly irregular in geometry and structurally controlled by variable trends (north-south to northwest-southeast) around the Milpo stock. For the vein mineralization, at least three groups were identified: (1) east-west striking; (2) replacement-style structures striking northwest-southeast dipping to the north; (3) and veins associated with intrusive dikes striking northeast-southwest; dipping to the south, and for the “mantos”, a northwest trending with shallow dipping to the south was recognized.

 

 

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Figure 11-2: El Porvenir Lithological and Control Type Domains

  

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

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Figure 11-3: El Porvenir Structure and Emplacement Type Domains

  

 

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11.4 Geological Modelling

 

Nexa performed geological modelling of the Porvenir deposit using Leapfrog. All contact surfaces were modelled based on the drilling and channel sampling assay results, as well as the structural and lithological controls observed in underground workings and drill core logging data. A total of 41 interpreted cross sections and 40 levels with underground mapping were used to guide the modelling (Figure 11-4), and polylines were used to better control contacts where data was sparse and to mimic underground mapping to adjust for mineralization displacement. No minimum mining thickness was used for the mineralization wireframes because DSO shapes were used for resource reporting.

 

The vein and “mantos” were modelled as vein objects and grouped using the vein system tool, with no consideration for external lithologies. Orebody type mineralization style was modelled using the intrusion tool. Extra boundary control was imposed using polylines if necessary. The modelled mineralized zones were then exported to Datamine software to encode the block model. A total of 430 individual mineralization domains (Table 11-2) and a total of 24 mineralization group zones were interpreted and modelled (Table 11-3). Most of the mineralization group zones are in the operation area, with exception of Sara and Porvenir 2 Sur Oeste. Figure 11-5 and Figure 11-6 illustrate the mineralization group zone domain solids in plan view and cross sections, respectively.

 

 

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Figure 11-4: OB_Vcn3 showing drill holes and updated mapping

 

 

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Table 11-2:  Individual Mineralization Domains

Nexa Resources S.A. – El Porvenir Mine

 

Mineralization Group Zone   Individual Mineralization Domain
Don Ernesto   de1,de2,de3,de4,de5
     
Don Lucho   dl01,dl02,dl03,dl04,dl05,dl06,dl07,dl08,dl09,dl10,dl11
     
Exito  

cpoex1,cpoex2,exit10,exit11,exit12,exit13,exit16,exit17,exit18,exiti1,exiti2,exiti3,exiti4,exiti5,exiti6,exiti7,exito,exito1,exito2,exito3,exito4,exito5,exito6,exito7,exito8, exito9,exitoa,exitob,exitoc,exitod,exits,exits1,exits2,exits3,exits4,exits5,exits6,exits7,exits8

     
Integracion AT-EP   int1,int10,int2,int3,int4,int5,int6,int7,int8,int9,ints1,ints10,ints11,ints12,ints13,ints14,ints15,ints16,ints17,ints21,ints22,ints23,ints24,ints25,ints26,ints28,ints29 ,ints3,ints 31,ints32,ints4,ints5,ints6,ints7
     
Porvenir 3   vpor31,vpor32,vpor33,vpor34,vpor35,vpor36,vpor37,vpor38
     
Porvenir 9   por9,por91,por92,por93,por94,por95,por96,por97,por98,por9a,por9b,por9c,por9cf1,por9cf2,por9cf3,por9cf4,por9cf5,por9cf6,por9cf7,por9cf8,por9e,por9f,por9g,por9h, or9i,por9j,por9l,por9m,por9n,por9o,por9p,por9q,por9r,por9s,por9t,por9u,por9v,por9w,por9x,por9y,por9z,porv9a,porv9e,porv9f,porv9w,porv9x
     
Porvenir 2 Sur Este   p2se1,p2se10,p2se11,p2se12,p2se13,p2se14,p2se15,p2se16,p2se17,p2se18,p2se2,p2se3,p2se4,p2se5,p2se6,p2se7,p2se8,p2sr,por2sd
     
Porvenir 2 Sur Oeste   p2sw1,p2sw10,p2sw11,p2sw12,p2sw13,p2sw14,p2sw15,p2sw16,p2sw17,p2sw18,p2sw19,p2sw2,p2sw20,p2sw21,p2sw22,p2sw23,p2sw24,p2sw25,p2sw2 6,p2sw27,
p2sw28,p2sw29,p2sw3,p2sw4,p2sw5,p2sw6,p2sw7,p2sw8,p2sw9
     
Sara   sara1,sara2,sara3,sara4,sara5,sara6,saras1,saras2,saras3,saras4,saras5,saras6
     
Socorro 2 y 4   soc21,soc210,soc211,soc212,soc213,soc214,soc22,soc23,soc24,soc25,soc27,soc28,soc29,soc41,soc410,soc411,soc412,soc413,soc414,soc42,soc43,so c434,soc435,soc436,soc437,soc44,soc45,soc46,soc47,soc48,soc49
     
Veta 1204   v12,v122,v123,v125,v1252,v126,v127,v12ne
     
Veta 1204 Inferior   v12i1,v12i10,v12i11,v12i12,v12i13,v12i14,v12i15,v12i16,v12i17,v12i18,v12i1a,v12i1b,v12i1c,v12i1d,v12i2,v12i3,v12i4,v12i5,v12i6,v12i7,v12i8,v12i9
     
Veta 1204 Superior   v12s1,v12s10,v12s11,v12s12,v12s13,v12s14,v12s15,v12s16,v12s17,v12s18,v12s19,v12s2,v12s21,v12s22,v12s23,v12s24,v12s25,v12s26,v12s27,v12s28,v12 s29,v12s3,v12s30,v12s31,v12s32,v12s33,v12s34,v12s35,v12s36,v12s37,v12s4,v12s5,v12s6,v12s7,v12s8,v12s9
     
Veta 5   v5i,v5ne1,v5ne2,v5ne3,v5ne4,v5ne5,v5ne6,v5nw1,v5nw10,v5nw11,v5nw12,v5nw13,v5nw14,v5nw15,v5nw16,v5nw17,v5nw18,v5nw19,v5nw2,v5nw20,v5nw21,
v5nw3,v5nw4,v5nw5,v5nw6,v5nw7,v5nw8,v5nw9
     
Veta AM   am1,am12,am14,am16,am17,am20,am21,am23,am3,am4,am8,am9,amsk1,amsk10,amsk11,amsk13,amsk14,amsk15,amsk16,amsk17,amsk18,amsk2,am sk3,amsk4,amsk5,amsk6,amsk7,amsk8,amsk9
     
Veta BX   bx
     
Veta Carmen Norte 1   vcn12,vcn13,vcn14,vcn15,vcn16,vcn17,vcn18,vcarmn
     
Veta Carmen Norte 3   cn3ei1,cn3ei2,vcn3,vcn32,vcn324,vcn327,vcn3e1,vcn3e3,vcn3e6,vcn3e8,vcn3w1,vcn3w2,vcn3w4,vcn3w5,vcn3w6,vcn3w8,vcn3w9
     
Veta Carmen Norte 4   vcn41,vcn42,vcn43,vcn44,vcn45,vcn46,vcn4i
     
Veta Carmen 1   vc1,vc1a,vc1b,vc1c
     
Veta Carmen 2   vc21,vc214,vc215,vc216,vc217,vc222,vc224,vc24,vc26,vc2922
     
Veta Carmen 3   vc31,vc32,vc33,vc34,vc35
     
Veta Progreso   vprg,vprg1,vprg2,vprg3,vprg4,vprg5,vprg6,vprgb,vprgb1,vprgb2,vprgb3,vprgb4,vprgb5,vprgb6,vprgb7,vprgb8,vprgb9,vprgba,vprgbb
     
Veta Vr   vr,vr1

 

 

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Technical Report Summary - January 15, 2021

 

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Table 11-3: Mineralization Group Zone Domains

Nexa Resources S.A. – El Porvenir Mine

 

Mineralization Group
Zone
  Volume (m3)   Lithological
Control
  Rock
Type
  Structure
Type
  Emplacement
Type
Don Ernesto   394,265.02   Fault   Sandstone   Mineralized body   Structural
Don Lucho   766,128.63   Contact   Skarn   Mineralized body   Exoskarn
Éxito   2,763,581.47   Contact   Skarn   Mineralized body   Exoskarn
Integracion AT-EP   954,292.48   Fault/ Contact   Breccia-Skarn   Mineralized body   Breccia-Exoskarn
Porvenir 3   340,210.92   Fault   Sandstone   Mineralized body   Replacement Contact
Porvenir 9   7,067,926.99   Fault/ Contact   Sandstone-Skarn   Mineralized body   Exoskarn-Replacement
Porvenir 2 Sur Este   1,023,911.97   Fault   Sandstone   Mineralized body   Breccia-Structural-Replacement
Porvenir 2 Sur Oeste   1,893,829.62   Fault   Sandstone   Mineralized body   Replacement Contact
Sara   1,881,233.84   Fault   Sandstone   Mineralized body   Replacement Contact
Socorro 2 y 4   576,392.07   Fault   Marmol   Vein   Structural
Veta 1204   484,165.83   Fault   Marmol   Vein   Structural
Veta 1204 Inferior   1,189,380.33   Fault   Marmol   Vein   Structural
Veta 1204 Superior   1,228,289.40   Fault   Marmol   Vein   Structural
Veta 5   1,503,477.81   Fault/ Contact   Skarn   Mineralized body   Exoskarn
Veta AM   490,337.52   Contact   Skarn   Mineralized body   Exoskarn
Veta BX   4,679.90   Fault   Breccia   Mineralized body   Breccia
Veta Carmen Norte 1   604,381.53   Contact   Skarn   Mineralized body   Exoskarn
Veta Carmen Norte 3   3,710,274.16   Contact   Skarn   Mineralized body   Exoskarn
Veta Carmen Norte 4   461,265.07   Fault/ Contact   Marmol-Skarn   Vein   Structural-Exoskarn
Veta Carmen 1   850,357.73   Fault   Marmol   Vein   Structural
Veta Carmen 2   296,457.86   Fault   Marmol   Vein   Structural
Veta Carmen 3   404,796.21   Fault   Marmol   Vein   Structural
Veta Progreso   4,857,800.73   Contact   Skarn   Mineralized body   Exoskarn
Veta Vr   29,941.27   Fault   Marmol   Vein   Structural

 

 

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Figure 11-5: El Porvenir Mineralization Group Zone Domains – Plan view

 

 

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Figure 11-6: El Porvenir Mineralization Group Zone Domains – Cross Section

 

 

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11.5 Domain Modelling

 

11.5.1 Grade Domains

 

Nexa prepared grade domain models for some of the individual mineralization domains by creating grade envelope wireframes based on assay grades. Grade threshold limits used to outline grade envelopes, and to define high and low grade domains, were determined by assessing probability plots, histograms, and contact plots to identify different populations, and by also considering spatial grade continuity.

 

A total of eight grade envelopes were built within the individual mineralization domains for Zn, Cu, Pb, and Ag. Silver and lead used the same grade domains as they were found statistically and spatially correlated.

 

The purpose of building high grade and low grade domains was to control the internal dilution and limit the smearing of high grade areas into low grade areas and vice versa, during the grade estimation. Table 11-4 lists the zinc, copper, silver, and lead grade domains and Figure 11-7 illustrates a 3D view of the grade domains in the VCN3 mineralization domain.

 

For the remaining individual mineralization domains, grade domains were not built.

 

Table 11-4: Zn, Cu, Ag, and Pb Grade Domains 

Nexa Resources S.A. – El Porvenir Mine

 

Individual
Mineralization
Domains
  COD_OB   Domain
by
Element
  Grade
Domain
  C_Estim   Domain
Type
  Mean
Grade of
Domain
  Grade Envelope
Por9   450   Zn   1   4501   Low Grade   3.30%   Outside 2%Zn envelope
Por9   450   Zn   2   4502   High grade   6.20%   Inside 2% Zn envelope
v5ne1   1750   Zn   1   17502   Low Grade   3.40%   Outside 10% Zn envelope
v5ne1   1750   Zn   2   17501   High grade   8.10%   Inside 10% Zn envelope
v12i1   259   Ag   1   2592   Low Grade   22.2 g/t   Outside 60 g/t Ag envelope
v12i1   259   Ag   2   2591   High grade   71.5 g/t   Inside 60 g/t Ag envelope
v12i1   259   Pb   1   2592   Low Grade   0.10%   Outside 0.1% Pb envelope
v12i1   259   Pb   2   2591   High grade   0.60%   Inside 0.1% Pb envelope
vcn3   1151   Cu   1   11511   Low Grade   0.10%   Outside 0.1% Cu envelope
vcn3   1151   Cu   2   11512   High grade   0.30%   Inside 0.1% Cu envelope

 

 

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Figure 11-7: Plan and Cross Section Copper Grade Domains for VCN3

 

 

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11.5.2 Estimation Domains

 

Based on observations of the drill core and underground mineralization exposures, discussions with the geologists on-site, a review of the data in 3D, and statistical analysis, the mineralization at Porvenir is considered to be lithologically and structurally controlled. The bulk of the mineralization is located in the Porvenir 9, Don Ernesto, Exito, Veta Carmen Norte 3, Veta Progreso, and Sara, with some mineralization in the Veta 5, Veta 1204, Veta 1204 Inferior, Veta 1204 Superior, Veta Carmen 1 and Don Lucho, and lesser mineralization in the Veta VR, and Integracion AT-EP domains.

 

Nexa created zinc, lead-silver, and copper estimation domains using a number of geological parameters, which include geological domains (lithological control and mineralization type), grade domains (high grade and low grade domains), and the anisotropy and orientation of the estimation domains. A total of 91 zinc, 69 lead-silver, and 70 copper estimation domains were defined. Table 11-5, Table 11-6, and Table 11-7 summarize the estimation domains and Figure 11-8, Figure 11-9, and Figure 11-10 show the estimation domains in plan view.

 

 

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Table 11-5: Zinc Estimation Domains

Nexa Resources S.A. – El Porvenir Mine 

 

C_ESTZN   Domains_Zn   C_ESTZN   Domains_Zn
1   vc1,vc1a,vcn12,vcn14,vcn17,vcn18,vprg2   1408   dl03,dl06,exit17,exito3,exito4
100   soc23,soc25,soc28,vc1c,vc21,vc24,vc26,vc31,vc35,vcn3w5   1410   exit10,exit12,exit13,exito5,exitod
154   ints7,soc214,vc1b,vc214,vcarmn,vcn13,vcn32,vcn327,vcn3e6   1450   exits1,v12s1,vprgb6
157   vc216,vc217   1452   am21,exit16,exits2,exits3,exits5,exits7,exits8,v12s2,vprgb2,vprgb4,vprgb5,vprgb8,vprgb9
250   v12i10,v12i8,vc215   1458   exits,vprgb3,vprgba,vprgbb
256   v12i13,v12i16,v12s17,v5nw17   1504   exiti1,exiti2,exiti3,exiti4,exiti5,exiti7,v12i1a
259   v12i1   1555   ints17,soc21,soc211,soc22,soc27,v12i2,v12i5,v5nw1,v5nw14,v5nw15,vc222,vc224,vcn324,vcn3e1,vcn 3e3,vcn3w1,vcn3w2,vcn3w4,vcn3w6,vcn3w8
302   vprg3,vprg5   1558   ints14,soc210,soc212,soc213,soc24,soc29,soc413,vc2922,vc32,vc33,vc34,vcn3w9
307   vprg,vprg1,vprg4,vprg6,350,por9a,por9b,por9m,porv9e,porv9f   1607   soc41,soc411,soc414,soc42,soc43,soc44,soc49
450   por9   1609   soc410,soc412,soc45,soc46,soc47,soc48
453   ints29,por9c,por9e,por9j,por9l   1614   soc434,soc435,soc436,soc437,1650,v5i,vcn4i
458   ints4,por9f,por9g,por9h,por9i,por9n,466,por91,por96,por98,por9p,por9q,porv9a   1702   v12i14,v5nw12,v5nw5,1712,v127,v12i18,v12i9,v5nw10,v5nw11,v5nw16,v5nw21,v5nw9,1714,v12i11,v1 2i12,v12i15,v12i17,v5nw3,v5nw4,1718,v5nw2,v5nw7
453   ints29,por9c,por9e,por9j,por9l   1750   v5ne1
458   ints4,por9f,por9g,por9h,por9i,por9n   1755   v5ne6
466   por91,por96,por98,por9p,por9q,porv9a   1855   v12s12,vcn46
550   por9v,por9w,porv9w   1950   p2se10,p2se11,p2se12,p2se13,p2se5,p2se8,saras2
600   por92,por93,por94,por95,por97,por9o,por9r,por9s,por9t,por9u,por9x,por9y,por9z,porv9x   1959   p2se1,p2se4
652   p2sw11,p2sw12,p2sw19,p2sw20,p2sw21,p2sw23,p2sw25,p2sw28,p2sw29,p2sw9   2000   p2sr,p2sw24,p2sw3,p2sw6,p2sw7
671   p2sw1,p2sw16,p2sw2   2051   int1,int10,int2,int3,int4,int5,int6,int7,int8,int9
674   p2sw17,p2sw18,p2sw22,p2sw4,p2sw5   2060   ints1,ints11,ints12,ints13,ints28
677   p2sw10,p2sw13,p2sw14,p2sw15,p2sw26,p2sw27,p2sw8   2065   ints31,ints6
700   de1,de3,de4,de5   2067   ints10,ints23,ints3
701   de2,sara2   2072   ints15,ints26
750   vpor31,vpor33,vpor35   2073   ints16
751   vpor32,vpor34   2079   ints24,ints25
756   vpor36,vpor37,vpor38   2100   dl01,dl02,dl04,dl08,dl10,dl11,exit18,v12s22,vprgb1
800   amsk10,amsk2,bx,ints22,ints5   2104   dl05,dl07,dl09
850   am1,am16,am8,am9,amsk3,amsk8,p2se14   2150   sara1,sara3,sara4,sara5,sara6
860   am12,am20,am3,amsk18,amsk5,amsk9,p2se15,p2se16,p2se17   2156   saras1,saras3,saras4,saras5,saras6
865   am14,am17,am4,amsk14   270   exiti6,v12i1b,v12i1c,v12i1d
872   am23,amsk1,amsk11,amsk15,amsk16,amsk7   1850   vcn41,vcn42,vcn43,vcn44,vcn45
883   amsk13,amsk17,amsk4,amsk6   1754   v12s24,v12s30,v12s31,v12s34,v12s7,v5ne2,v5ne3,v5ne4,v5ne5
901   v12,v122,v123   264   v12i3,v12i4,v12i6,v12i7
908   v125,v1252,v126   201   vr,vr1
950   v12ne,v12s13   306   exits6,vprgb,vprgb7
1016   exito7,v12s14,v12s16,v12s23,v12s26,v12s28,v12s36   1008   v12s18,v5nw13
1019   v12s29,v12s5,v12s8,v5nw6,1026,v12s15,v12s19,v12s32,v12s35   1900   p2se2,por2sd
1028   exito6,v12s10,v12s11,v12s3,v12s33,v12s37   1965   p2se18,p2se3,p2se6,p2se7
1029   exito2,exits4,v12s4,v12s6,v5nw18,v5nw19,v5nw20   21   por9cf1,por9cf2,por9cf3,por9cf4,por9cf5,por9cf6,por9cf7,por9cf8
1034   v12s21,v12s25,v12s27,v12s9   1151   vcn3
1054   vcn15,vcn16   259   v12i1
1151   vcn3   17501   v5ne1
1208   ints21,ints32,vcn3e8   17502   v5ne1
1300   cn3ei1,cn3ei2   4501   por9
1350   cpoex1,cpoex2,exit11,exitoa,exitob   4502   por9
1402   exito,exito1,exito8,exito9,exitoc        

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-17

 

 

Table 11-6: Lead-Silver Estimation Domains

Nexa Resources S.A. – El Porvenir Mine 

  

CESTIM_AG-PB   Domains_Ag   CESTIM_AG-PB   Domains_Ag
1   ints7,vc1,vc224,vc26,vc32,vcarmn,vcn13,vcn16,vprg2   1404   exit11,exito8,exito9,exitoa,exitob
100   soc24,soc27,vc21,vc24,vc2922,vc31,vc33,vc35,vcn14,vcn15   1408   dl01,dl02,dl03,dl10,dl11,exit17,exito3,exito4,v12s22
154   ints17,soc210,soc213,soc23,soc25,soc29,v12i2,v12i5,v5nw1,vc1a,vc1b,vc1c,vc214,vc34,vcn17,vcn18, vcn327,vcn3w1,vcn3w2,vcn3w4,vcn3w5,vcn3w6,vcn3w8   1450   exits1,exits3,v12s1,vprgb6
157   vc216,vc217   1458   exits,exits6,vprgb,vprgb7
185   exito2,exits4,v12s18,v12s4,v12s6,v5nw13,v5nw18,v5nw19,v5nw20   1504   exiti1,exiti2,exiti3,exiti4,exiti5,exiti6,exiti7,v12i1a,v12i1b,v12i1c,v12i1d
201   vr,vr1   1555   ints14,soc21,soc211,soc212,soc214,soc22,soc28,soc413,v5nw14,v5nw15,vc222,vcn12,vcn32,vcn324,
vcn3e1,vcn3e3,vcn3e6
256   v12i13,v12i16,v12s17,v5nw17   1607   soc41,soc410,soc412,soc414,soc42,soc43,soc45,soc48
264   v12i3,v12i4,v12i6,v12i7   1611   soc411,soc44,soc46,soc47,soc49
307   vprg,vprg1,vprg3,vprg4,vprg5,vprg6   1614   soc434,soc435,soc436,soc437
308   dl04,dl06,dl08,exit18,vprgb1   1650   v5i,vcn4i
309   am21,exit16,exits2,exits5,exits7,exits8,v12s2,vprgb2,vprgb4,vprgb5,vprgb8,vprgb9   1712   v127,v12i11,v12i12,v12i15,v12i17,v12i18,v12i9,v5nw10,v5nw11,v5nw16,v5nw21,v5nw3,v5nw4,v5nw9
310   vprgb3,vprgba,vprgbb   1716   v12i10,v12i14,v12i8,v12s29,v12s5,v12s8,v5nw12,v5nw5,v5nw6,vc215
350   porv9e   1718   v5nw2,v5nw7,v5nw8
451   por9a,por9b,por9m,porv9f   1850   vcn41,vcn42,vcn43,vcn44,vcn45
456   ints4,por9e,por9f,por9j,por9l   1855   v12ne,v12s12,v12s13,v12s25,v12s30,v12s31,v12s34,v5ne3,v5ne5,vcn46
458   ints29,por9c,por9g,por9h,por9i,por9n   1900   p2se1,p2se12,p2se4,por2sd
466   por91,por92,por93,por94,por95,por9o,por9p,por9q,por9t,por9y,por9z   1960   p2se10,p2se11,p2se13,p2se2,p2se5,p2se8,saras2
600   por96,por97,por98,por9r,por9s,por9u,por9v,por9w,por9x,porv9a,porv9w,porv9x   1965   p2se18,p2se3,p2se6,p2se7
671   p2sw1,p2sw13,p2sw15,p2sw2,p2sw20,p2sw3,p2sw5,p2sw6,p2sw8   2000   p2sr,p2sw10,p2sw11,p2sw12,p2sw14,p2sw16,p2sw17,p2sw18,p2sw19,p2sw21,p2sw22,p2sw23,p2sw24,p2sw25,p2sw26,p2sw27,p2sw28,p2sw29,p2s
w4,p2sw7,p2sw9
700   de1,de3,de4,de5   2051   int1,int10,int2,int3,int4,int5,int6,int7,int8,int9
701   de2,sara1,sara2,sara3,sara4,sara5,sara6   2060   ints1,ints11,ints12,ints13,ints21,ints28,ints32,vcn3e8
750   vpor31,vpor33,vpor35   2067   ints10,ints23,ints3
751   amsk10,amsk2,bx,ints22,ints5,vpor32,vpor34   2073   ints16
756   vpor36,vpor37,vpor38   2079   ints24,ints25
850   am1,am12,am16,am20,am3,am8,am9,amsk18,amsk3,amsk5,amsk8,amsk9,p2se14,p2se15,p2se16,p2 se17   2080   ints15,ints26
865   am17,am4,amsk1,amsk14,amsk16   2083   ints31,ints6
878   am14,am23,amsk11,amsk15,amsk7   2104   dl05,dl07,dl09
883   amsk13,amsk17,amsk4,amsk6   2156   saras1,saras3,saras4,saras5,saras6
901   v12,v122,v123   21   por9cf1,por9cf2,por9cf3,por9cf4,por9cf5,por9cf6,por9cf7,por9cf8
908   v125,v1252,v126   1151   vcn3
1028   exito6,exito7,v12s10,v12s11,v12s14,v12s15,v12s16,v12s19,v12s23,v12s26,v12s28,v12s3,v12s32,v12 s33,v12s35,v12s36,v12s37   2591   v12i1
1034   v12s21,v12s24,v12s27,v12s7,v12s9,v5ne2,v5ne4,v5ne6   2592   v12i1
1300   cn3ei1,cn3ei2   1750   v5ne1
1351   cpoex2,exit10,exit12,exit13,exito5   450   por9
1402   cpoex1,exito,exito1,exitoc,exitod        

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-18

 

 

Table 11-7: Copper Estimation Domains

 

CESTIM_CU   Domains_Cu   CESTIM_CU   Domains_Cu
1   ints14,ints17,v12i2,v12i5,vc1,vc1a,vc1b,vcn12,vcn16,vcn32,vcn3w9,vprg2   1404   exito5,exitob,exitoc,exitod
100   soc21,soc210,soc211,soc212,soc213,soc214,soc22,soc23,soc24,soc25,soc28,soc29,soc413,
v5nw1,v5nw14,v5nw15,vc1c,vc21,vc214,vc222,vc224,vc24,vc26,vc2922,vc31,vc32,vc33,vc34,
vc35,vcn3e3,vcn3e6,vcn3w1,vcn3w4,vcn3w5,vcn3w6
  1408   dl01,dl02,dl03,dl04,dl06,dl08,dl10,dl11,exit17,exit18,exito3,exito4,v12s22,vprgb1
157   vc216,vc217   1450   exit16,exits1,exits5,exits7,exits8,vprgb8,vprgb9
164   por92,por95,por9t,por9y   1455   exits6,vprgb3,vprgb7,vprgba,vprgbb
201   vr,vr1   1458   exits,vprgb
252   v12i12,v12i15,v12i17,v12i9   1502   exiti1,exiti2,exiti3,exiti4,exiti7
264   v12i3,v12i4,v12i6,v12i7   1504   exiti5,exiti6,v12i1a,v12i1b,v12i1c,v12i1d
307   vprg,vprg1,vprg3,vprg4,vprg5,vprg6   1607   soc41,soc410,soc411,soc412,soc414,soc42,soc43,soc44,soc45,soc46,soc47,soc48,soc49
350   por9a,por9b,por9m,porv9e,porv9f   1614   soc434,soc435,soc436,soc437
456   por9c,por9f,por9n   1650   v5i,vcn4i
458   ints29,ints4,por9e,por9g,por9h,por9i,por9j,por9l   1702   v12i10,v12i13,v12i14,v12i16,v5nw12,v5nw6,vc215
466   por91,por93,por94,por96,por97,por98,por9o,por9p,por9q,por9r,por9s,por9u,por9v,por9w,por9x ,por9z , porv9a,porv9w,porv9x   1712   v127,v12i11,v12i18,v5nw10,v5nw11,v5nw16,v5nw21,v5nw3,v5nw4,v5nw9
671   p2sr,p2sw1,p2sw10,p2sw11,p2sw12,p2sw13,p2sw14,p2sw15,p2sw16,p2sw17,p2sw18,p2sw19,
p2sw2,p2sw20,p2sw21,p2sw22,p2sw23,p2sw
24,p2sw25,p2sw26,p2sw27,p2sw28,p2sw29,p 2sw3,p2sw4,p2sw5,p2sw6,p2sw7,p2sw8,p2sw9
  1716   v12i8,v12s17,v12s29,v12s5,v12s8,v5nw17,v5nw5
700   de1,de3,de4,de5   1718   v5nw2,v5nw7,v5nw8
701   de2,sara1,sara2,sara3,sara4,sara5,sara6   1850   vcn41,vcn42,vcn43,vcn44,vcn45
750   vpor31,vpor33,vpor35   1855   v12ne,v12s13,v5ne4,v5ne6,vcn46
751   amsk10,amsk2,bx,ints22,ints5,vpor32,vpor34   1900   p2se1,p2se10,p2se11,p2se12,p2se13,p2se4,p2se5,p2se8,por2sd
756   vpor36,vpor37,vpor38   1960   p2se2,saras2
852   am14,am4,amsk14,amsk15,amsk16   1965   p2se18,p2se3,p2se6,p2se7
860   am1,am12,am3,am8,am9,amsk18,amsk9,p2se14,p2se15,p2se16,p2se17   2051   int1,int10,int2,int3,int4,int5,int6,int7,int8,int9
864   am16,am20,amsk3,amsk5,amsk8   2060   ints1,ints11,ints13,ints21,ints28,vcn3e8
865   am17,am23,amsk1,amsk11,amsk7   2065   ints31,ints6
883   amsk13,amsk17,amsk4,amsk6   2067   ints10,ints23,ints3
901   v12,v122,v1252   2069   ints12,ints32
902   v123,v125,v126   2072   ints15,ints26
1004   v12s14,v12s28   2073   ints16
1008   exits4,v12s18,v5nw13,v5nw18,v5nw19,v5nw20   2079   ints24,ints25
1010   am21,exits2,exits3,v12s1,v12s2,vprgb2,vprgb4,vprgb5,vprgb6   2104   dl05,dl07,dl09
1023   v12s10,v12s11,v12s15,v12s16,v12s19,v12s23,v12s26,v12s32   2156   saras1,saras3,saras4,saras5,saras6
1028   exito6,exito7,v12s3,v12s33,v12s35,v12s36,v12s37   21   por9cf1,por9cf2,por9cf3,por9cf4,por9cf5,por9cf6,por9cf7,por9cf8
1029   exito2,v12s4,v12s6   11511   vcn3
1034   v12s12,v12s21,v12s24,v12s25,v12s27,v12s30,v12s31,v12s34,v12s7,v12s9,v5ne2,v5ne3,v5n e5   11512   vcn3
1051   ints7,soc27,vcarmn,vcn13,vcn14,vcn15,vcn17,vcn18,vcn324,vcn327,vcn3e1,vcn3w2,vcn3w8   259   v12i1
1300   cn3ei1,cn3ei2   1750   v5ne1
1402   cpoex1,cpoex2,exit10,exit11,exit12,exit13,exito,exito1,exito8,exito9,exitoa   450   por9

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-19

 

 

 

Figure 11-8:               Zinc Domains

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-20

 

 

 

Figure 11-9:           Lead-Silver Domains

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-21

 

 

 

Figure 11-10:            Copper Domains

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-22

 

 

With respect to the geological and domain modelling used to support the Mineral Resource estimate, SLR offers the following conclusions and recommendations:

 

Overall, the mineralization wireframes are adequate for the style of mineralization.

 

The wireframes and estimation domains are suitable to support Mineral Resource and Mineral Reserve estimation.

 

There is an opportunity to increase the volume of the mineralization solids. SLR observed some areas where mineralization intervals with high grades were close but excluded from the domain solids.

 

Update the lithological model (it has not been updated since 2018) and build a litho-structural model with the main lithologies and faults that are controlling the mineralization, with all the data available, to help define the geometry and boundaries of the mineralization. An updated lithological model would also be beneficial to evaluate and define density values by rock and by domain.

 

Some interpreted sections, plan views, and underground mapping were used to build the mineralization solids, however, there is no new 3D lithological model.

 

Three faults (F1_Exito, F2_Exito, and F1_VCN3) based on underground mapping were used in the model to define Exito and Carmen Norte 3 limits and movements. These faults were built projecting a unique dip, however, they should be interpreted in 3D to improve the understanding and controlling of the mineralization solids.

 

Nexa incorporated grade domains for zinc, lead-silver, and copper for some individual mineralization domains. SLR recommends reviewing the inclusion of more grade domains considering spatial and statistical correlations, to prevent smearing of high grades into low grade areas and vice versa.

 

Review inclusion of very low grade in the contacts of the modelled solid and exclude if they are not used to achieve minimum thickness.

 

Divide mineralization domains where groups of wireframes have been merged to avoid sharing of samples.

 

The interaction between Don Ernesto and Sara should be considered and possibly modelled as a continuous mineralization solid, especially if both mineralization structures (Don Ernesto lower levels and Sara) have the same host rock and mineralization features.

 

Include a logging code for each mineralization domain, structure type, and emplacement type to correlate with modelled domains.

 

Improve the survey accuracy of the mineralized mined-out stopes and development to guide the mineralization solid geometries and trends.

 

11.6 Resource Assays

 

Nexa performed exploratory data analysis (EDA) for each estimation domain, including univariate statistics, histograms, cumulative probability plots; box plots to compare geology domain statistics, and contact plots to investigate grade profiles between estimation domains and determine the extent of sample sharing across the geology contacts within the mineralization domains. Hard boundaries were determined for each of the estimation variables (zinc, copper, lead, and silver). The majority of the zinc is contained in eight estimation domains: vcn3, por9, porv9a, vprg, exito, por9p, por9q, and porv9w.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-23

 

 

11.7 Treatment of High Grade Assays

 

11.7.1 Capping Levels

 

Where the assay distribution is skewed positively or approaches log-normal, erratic high grade values can have a disproportionate effect on the average grade of a deposit. One method of treating these outliers in order to reduce their influence on the average grade is to cut or cap them at a specific grade level.

 

Nexa evaluated the raw assay grades using log-probability plots and histograms to assess the influence of higher grades for each element within the mineralization domains. Figure 11-11 is an example of a log-probability plot for the OB 1300 (vcn3ei1) domain. The criteria, applied by Nexa, for restricting outliers was to identify a pronounced break in the probability curve that occurs above the 95th to 99th percentile. Nexa applied a second capping level for the third interpolation pass in channel composites to restrict the high grade influence.

 

Table 11-8 lists the capping levels for drill hole (“CAPD”) and channel (“CAPC”) raw assays determined for each mineralization domain, and the second capping levels applied to the channel samples used for the third interpolation pass (“CAPC3”). A summary of raw assays and capped raw assays statistics is provided in Table 11-9, Table 11-10, Table 11-11, and Table 11-12.

 

 

 

Figure 11-11:             Zn Capping Analysis for 1300 (VCN3EI1) Domain

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-24

 

 

Table 11-8:        Capping Levels by Mineralization Domains

Nexa Resources S.A. – El Porvenir Mine 

 

Domain   ZN_D   ZN_C   ZN_C3   PB_D   PB_C   PB_C3   CU_D   CU_C   CU_C3   AG_D   AG_C   AG_C3   Grade   Domain   ZN_D   ZN_C   ZN_C3   PB_D   PB_C   PB_C3   CU_D   CU_C   CU_C3   AG_D   AG_C   AG_C3   Grade
Ore Body   (%)   (%)   (%)   (%)   (%)   (%)   (%)   (%)   (%)   (g/t)   (g/t)   (g/t)   Domain   Ore Body   (%)   (%)   (%)   (%)   (%)   (%)   (%)   (%)   (%)   (g/t)   (g/t)   (g/t)   Domain
de1   31   42.5   35.4   -   20   18.7   0.12   0.1   0.07   1790   1200   546.67   1   soc412   17   2   2   15   15   8   -   -   -   1250   750   750   1
de2   29   39   16.92   22   28   15.7   0.45   -   0.31   2000   3000   1234.81   1   soc413   34.5   16.5   16.5   15   15   12   1.6   1.3   1.3   1600   1800   1800   1
de3   31   42.5   42.5   -   20   20   0.12   0.1   0.1   1790   1200   1200   1   soc414   32   10.8   0.42   15   15   0.44   -   -   0.04   1250   750   165.28   1
de4   31   42.5   42.5   -   20   20   0.12   0.1   0.1   1790   1200   1200   1   soc434   23   -   4   20   -   -               1155   -   -   1
de5   31   42.5   42.5   -   20   20   0.12   0.1   0.1   1790   1200   1200   1   soc435   23   -   4   20   -   -               1155   -   -   1
exit10   17   -   -   2   -   -   8.2   -   -   600   -   -   1   soc436   23   -   0.2   20   -   0.12   -   -   -   1155   -   6.28   1
exit11   27.5   24.5   24.5   12   -   -   8.2   -   -   900   -   -   1   soc437   23   -   6.63   20   -   5.96   -   -   0.1   1155   -   268.05   1
exito   31   13   10.56   12   8   6.45   8.2   -   0.79   712   400   208.69   1   v5i   29   36   18.9   0.3   4   1.86   5   2.5   0.98   300   400   142.5   1
exitoa   27.5   24.5   24.5   12   -   -   8.2   -   -   900   -   -   1   v5ne2   29   10.4   10.4   14   10   10   0.63   -   -   700   244   200   1
exitob   27.5   24.5   24.5   12   -   -   3.4   -   -   900   -   -   1   v5ne3   29   10.4   8.64   22   22   19.5   0.63   -   0.25   1570   688   293.62   1
exito1   31   13   13   12   8   8   8.2   -   -   712   400   400   1   v5ne4   29   10.4   6.23   14   10   9   2.3   1.5   0.3   700   244   244   1
exit12   17   -   -   2   -   -   8.2   -   -   600   -   -   1   v5ne5   29   10.4   10.4   22   22   22   0.63   -   -   1570   688   688   1
exit13   17   -   -   2   -   -   8.2   -   -   600   -   -   1   v5ne6   25   28   28   14   10   10   2.3   1.5   1.5   700   244   200   1
exito2   25   10.8   10.8   18   15.8   3   2.9   -   -   1000   250   250   1   v5nw1   38.5   37   37   6.5   -   -   1.6   1.3   1.3   420   490   480   1
exito3   19   -   -   15   -   -   1.6   -   -   1050   -   -   1   v5nw2   13   14.5   6.77   3   -   1   0.13   -   0.05   200   214   92.19   1
exito4   19   -   -   15   -   -   1.6   -   -   1050   -   -   1   v5nw3   33   13.5   13.5   24   -   -   0.4   -   -   900   600   600   1
exito5   17   -   -   2   -   -   3.4   -   -   600   -   -   1   v5nw4   33   13.5   13.5   24   -   -   0.4   -   -   900   600   600   1
exitoc   31   13   13   12   8   8   3.4   -   -   712   400   400   1   v5nw5   36   17   11.95   25   18   11.59   -   -   0.31   844   570   330.68   1
exitod   17   -   -   12   8   8   3.4   -   -   712   400   400   1   v5nw6   24   -   -   25   18   18   1.4   -   -   844   570   570   1
exito6   23.5   15.5   15.5   25   11.5   11.5   0.82   -   -   2000   1000   1000   1   v5nw7   13   14.5   8.36   3   -   7.25   0.13   -   0.31   200   214   160.57   1
exito7   25   5   5   25   11.5   11.5   0.82   -   -   2000   1000   1000   1   v5nw8   13   14.5   14   3   -   1.2   0.13   -   0.12   200   214   210.04   1
exito8   31   13   13   12   -   -   8.2   -   -   900   -   -   1   v5nw9   23.5   15.5   15.5   24   -   -   0.4   -   -   900   600   600   1
exito9   31   13   13   12   -   -   8.2   -   -   900   -   -   1   v5nw10   23.5   15.5   15.5   24   -   -   0.4   -   -   900   600   600   1
exit16   26   13   12   20   13   6   -   -   -   800   400   400   1   v5nw11   23.5   15.5   10.71   24   -   7.63   0.4   -   0.38   900   600   570.81   1
exit17   19   -   -   15   -   -   1.6   -   -   1050   -   -   1   v5nw12   36   17   8.74   25   18   3.2   1.4   -   0.79   844   570   145.84   1
exit18   30   16.5   16.5   0.9   10   6   1.6   -   -   435   179   100   1   v5nw13   23   -   16.26   18   15.8   14   -   -   0.12   1000   250   250   1
cpoex1   27.5   24.5   22.75   12   8   6.87   8.2   -   0.54   712   400   379.62   1   v5nw14   38.5   37   3.23   15   15   3.46   1.6   1.3   0.05   1600   1800   109.9   1
cpoex2   27.5   24.5   24.5   2   -   -   8.2   -   -   600   -   -   1   v5nw15   38.5   37   37   15   15   12   1.6   1.3   1.3   1600   1800   1800   1
exiti1   23   15.5   15.5   0.1   0.2   0.2   7.5   -   -   210   70   50   1   v5nw16   23.5   15.5   15.5   24   -   -   0.4   -   -   900   600   600   1
exiti2   23   15.5   15.5   0.1   0.2   0.2   7.5   -   -   210   70   50   1   v5nw17   21   -   -   13.5   -   -   -           500   -   -   1
exiti3   23   15.5   6.64   0.1   0.2   0.02   7.5   -   0.38   210   70   11.73   1   v5nw18   25   10.8   10.8   18   15.8   3   -   -   -   1000   250   250   1
exiti4   23   15.5   15.5   0.1   0.2   0.2   7.5   -   -   210   70   50   1   v5nw19   25   10.8   10.8   18   15.8   3   -   -   -   1000   250   250   1
exiti5   23   15.5   6.99   0.1   0.2   0.02   4.9   -   2.66   210   70   35.99   1   v5nw20   25   10.8   10.8   18   15.8   3   -   -   -   1000   250   250   1
exiti6   31   -   -   0.1   0.2   0.2   4.9   -   -   210   70   50   1   v5nw21   23.5   15.5   15.5   24   -   -   0.4   -   -   900   600   600   1
exiti7   23   15.5   15.5   0.1   0.2   0.2   7.5   -   -   210   70   50   1   v12i1a   23   15.5   7.02   0.1   0.2   0.2   4.9   -   1.32   210   70   55.8   1
exits   26.5   30   9.92   14.4   12   6.97   -   1.5   0.64   1400   850   320.55   1   v12i1b   31   -   14.99   0.1   0.2   0.1   4.9   -   0.7   210   70   26.13   1
exits1   21   8   6.4   12   9.5   8.52   -   -   0.12   890   500   225.08   1   v12i1c   31   -   -   0.1   0.2   0.2   4.9   -   -   210   70   50   1
exits2   26   13   5.27   20   13   4.04   2   -   0.06   800   400   89.84   1   v12i1d   31   -   -   0.1   0.2   0.2   4.9   -   -   210   70   50   1
exits3   26   13   10.85   12   9.5   6.11   2   -   0.45   890   500   461.08   1   v12i2   38.5   37   37   6.5   -   -   6.2   2.7   2.7   420   490   480   1
exits4   25   10.8   9.84   18   15.8   2.73   -   -   0.08   1000   250   191.75   1   v12i3   33   -   -   -   -   -   7.9   -   -   60   -   -   1
exits5   26   13   7.02   20   13   5.4   -   -   0.08   800   400   400   1   v12i4   33   -   -   -   -   -   7.9   -   -   60   -   -   1
exits6   24   15   9.88   14.4   12   9.64   -   0.3   0.12   1400   850   457.07   1   v12i5   38.5   37   37   6.5   -   -   6.2   2.7   2.7   420   490   480   1
exits7   26   13   2.74   20   13   2.66   -   -   0.09   800   400   129.13   1   v12i6   33   -   -   -   -   -   7.9   -   -   60   -   -   1
exits8   26   13   12   20   13   6   -   -   -   800   400   400   1   v12i7   33   -   -   -   -   -   7.9   -   -   60   -   -   1
int1   16.5   -   -   8.4   -   -   1.7   -   -   2000   -   -   1   v12i8   21   32   18.1   25   18   7.13   -   -   0.4   844   570   247.27   1
int2   16.5   -   -   8.4   -   -   1.7   -   -   2000   -   -   1   v12i9   23.5   15.5   15   24   -   0.43   -   -   0.47   900   600   190.66   1
int3   16.5   -   -   8.4   -   -   1.7   -   -   2000   -   -   1   v12i10   21   32   15.74   25   18   1.71   1.4   -   0.75   844   570   224.64   1
int4   16.5   -   -   8.4   -   -   1.7   -   -   2000   -   -   1   v12i11   33   13.5   13.5   24   -   -   0.4   -   -   900   600   600   1
int5   16.5   -   -   8.4   -   -   1.7   -   -   2000   -   -   1   v12i12   33   13.5   9.13   24   -   0.99   -   -   1.54   900   600   260.8   1
int6   16.5   -   -   8.4   -   -   1.7   -   -   2000   -   -   1   v12i13   21   -   12.61   13.5   -   0.67   1.4   -   0.42   500   -   203.04   1
int7   16.5   -   -   8.4   -   -   1.7   -   -   2000   -   -   1   v12i14   36   17   3.33   25   18   0.07   1.4   -   0.36   844   570   23.89   1
int8   16.5   -   -   8.4   -   -   1.7   -   -   2000   -   -   1   v12i15   33   13.5   11.92   24   -   0.38   -   -   0.3   900   600   124.07   1
int9   16.5   -   -   8.4   -   -   1.7   -   -   2000   -   -   1   v12i16   21   -   -   13.5   -   -   1.4   -   -   500   -   -   1
int10   16.5   -   -   8.4   -   -   1.7   -   -   2000   -   -   1   v12i17   33   13.5   13.5   24   -   -   -   -   -   900   600   600   1
ints1   28   -   -   1.5   -   -   -   -   -   400   -   -   1   v12i18   23.5   15.5   15.5   24   -   -   0.4   -   -   900   600   600   1
ints3   14   -   -   -   -   -   -   -       50   -   -   1   v122   26.5   12.5   5.33   16   8   3.38   2.5   1.9   0.45   1000   250   184.37   1
ints4   24   9.5   9.5   5.5   -   -   5   -   -   450   47.4   47.4   1   v123   26.5   12.5   10.74   16   8   7   -   -   0.17   1000   250   250   1
ints5   8   -   -   20   37   12   0.25   0.26   0.26   420   1922   1922   1   v125   21   -   -   20   -   -   -   -   -   1400   -   -   1
ints6   20   -   -   0.05   -   -   -   -   -   29   -   -   1   v126   21   -   -   20   -   -   -   -   -   1400   -   -   1
ints7   38   31   31   30   30   30   1.7   1.1   1.1   2000   1000   1000   1   v127   23.5   15.5   3.08   24   -   5.51   0.4   -   0.22   900   600   253.96   1
ints10   14   -   -   -   -   -   -   -       50   -   -   1   v12   26.5   12.5   5.2   16   8   3.93   2.5   1.9   1.65   1000   250   225.47   1
ints11   28   -   -   1.5   -   -   -   -   -   400   -   -   1   v1252   21   -   -   20   -   -   2.5   1.9   1.3   1400   -   -   1
ints12   28   -   -   1.5   -   -   -   -   -   400   -   -   1   v12ne   33   17   16   22   22   13.76   2.3   1.5   0.59   1570   688   435.14   1
ints13   28   -   -   1.5   -   -   -   -   -   400   -   -   1   v12s1   21   8   8   12   9.5   9.5   2   -   -   890   500   500   1
ints14   34.5   16.5   16.5   15   15   12   6.2   2.7   2.7   1600   1800   1800   1   v12s2   26   13   12   20   13   6   2   -   -   800   400   400   1
ints15   9   -   -   -   -                               1   v12s3   23.5   15.5   13.03   25   11.5   8.89   0.82   -   0.44   2000   1000   782.73   1
ints16   4.5   -   -   -   -                               1   v12s4   25   10.8   5   18   15.8   3   2.9   -   -   1000   250   250   1
ints17   38.5   37   37   6.5   -   -   6.2   2.7   2.7   420   490   480   1   v12s5   24   -   -   25   18   18   -   -   -   844   570   570   1
ints21   41.5   -   -   1.5   -   -   -       -   400   -   -   1   v12s6   25   10.8   10.8   18   15.8   3   2.9   -   -   1000   250   250   1
ints22   8   -   -   20   37   12   0.25   0.26   0.26   420   1922   1922   1   v12s7   29   10.4   10.4   14   10   10   0.63   -   -   700   244   200   1

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-25

 

 

Domain   ZN_D   ZN_C   ZN_C3   PB_D   PB_C   PB_C3   CU_D   CU_C   CU_C3   AG_D   AG_C   AG_C3   Grade   Domain   ZN_D   ZN_C   ZN_C3   PB_D   PB_C   PB_C3   CU_D   CU_C   CU_C3   AG_D   AG_C   AG_C3   Grade
Ore Body   (%)   (%)   (%)   (%)   (%)   (%)   (%)   (%)   (%)   (g/t)   (g/t)   (g/t)   Domain   Ore Body   (%)   (%)   (%)   (%)   (%)   (%)   (%)   (%)   (%)   (g/t)   (g/t)   (g/t)   Domain
ints23   14   -   -   -                       50   -   -   1   v12s8   24   -   -   25   18   18   -   -   -   844   570   570   1
ints24   7.5   -   -                                       1   v12s9   25.5   -   -   14   10   10   0.63   -   -   700   244   200   1
ints25   7.5   -   -                                       1   v12s10   23.5   15.5   15.5   25   11.5   11.5   1.8   -   -   2000   1000   1000   1
ints26   9   -   -                                       1   v12s11   23.5   15.5   15.5   25   11.5   11.5   1.8   -   -   2000   1000   1000   1
ints28   28   -   -   1.5   -   -   -       -   400   -   -   1   v12s12   -   30   30   22   22   22   0.63   -   -   1570   688   688   1
ints29   41   -   -   0.3   0.1   0.1   5   -   -   57   61.5   58   1   v12s13   33   17   17   22   22   22   2.3   1.5   1.5   1570   688   688   1
ints31   20   -   -   0.05   -   -   -       -   29   -   -   1   v12s14   25   5   4   25   11.5   7.83   -   -   0.74   2000   1000   460.14   1
ints32   41.5   -   -   1.5   -   -   -       -   400   -   -   1   v12s15   19   10   10   25   11.5   11.5   1.8   -   -   2000   1000   1000   1
por2sd   17.5   -   15.04   12   14   7.14   0.86   0.9   0.38   1500   1000   391.59   1   v12s16   25   5   5   25   11.5   11.5   1.8   -   -   2000   1000   1000   1
p2se1   20   9.5   5.11   12   14   5.66   0.86   0.9   0.13   1500   1000   308.24   1   v12s17   21   -   -   13.5   -   -   -       -   500   -   -   1
p2se2   17.5   -   13.45   4   5.3   0.75   -   -   0.4   586   375   78.93   1   v12s18   23   -   -   18   15.8   3   -   -   -   1000   250   250   1
p2se3   12.5   12   6.1   5   7   6.58   0.15   -   0.15   400   438   316.24   1   v12s19   19   10   10   25   11.5   11.5   1.8   -   -   2000   1000   1000   1
p2se4   20   9.5   3.85   12   14   4.35   0.86   0.9   0.12   1500   1000   304.29   1   v12s21   25.5   -   1.57   14   10   1.51   0.63   -   0.03   700   244   106.61   1
p2se5   10.5   12   11   4   5.3   0.89   0.86   0.9   0.25   586   375   73.81   1   v12s22   30   16.5   16.5   15   -   -   1.6   -   -   1050   -   -   1
p2se6   12.5   12   3.67   5   7   2.04   0.15   -   0.08   400   438   192.34   1   v12s23   25   5   5   25   11.5   11.5   1.8   -   -   2000   1000   1000   1
p2se7   12.5   12   5.97   5   7   2.88   0.15   -   0.17   400   438   301.7   1   v12s24   29   10.4   10.2   14   10   7.47   0.63   -   0.16   700   244   244   1
p2se8   10.5   12   2.8   4   5.3   3.46   0.86   0.9   0.13   586   375   86.17   1   v12s25   25.5   -   -   22   22   22   0.63   -   -   1570   688   688   1
p2se10   10.5   12   6.47   4   5.3   5   0.86   0.9   0.18   586   375   167.71   1   v12s26   25   5   3.48   25   11.5   3.22   1.8   -   0.06   2000   1000   250.45   1
p2se11   10.5   12   3.34   4   5.3   3.98   0.86   0.9   0.04   586   375   276.82   1   v12s27   25.5   -   -   14   10   10   0.63   -   -   700   244   200   1
p2se12   10.5   12   4.06   12   14   0.27   0.86   0.9   0.27   1500   1000   310.88   1   v12s28   25   5   5   25   11.5   11.5   -   -   -   2000   1000   1000   1
p2se13   10.5   12   1.38   4   5.3   0.18   0.86   0.9   0.16   586   375   24.85   1   v12s29   24   -   -   25   18   18   -   -   -   844   570   570   1
p2se14   30   -   -   19   -   -   1   -   -   1400   -   -   1   v12s30   29   10.4   10.4   22   22   22   0.63   -   -   1570   688   688   1
p2se15   18   -   -   19   -   -   1   -   -   1400   -   -   1   v12s31   29   10.4   8.97   22   22   14.26   0.63   -   0.23   1570   688   688   1
p2se16   18   -   9.78   19   -   3.65   1   -   0.04   1400   -   133.14   1   v12s32   19   10   4.65   25   11.5   4.44   1.8   -   0.12   2000   1000   340.65   1
p2se17   18   -   -   19   -   -   1   -   -   1400   -   -   1   v12s33   23.5   15.5   6.79   25   11.5   8.11   0.82   -   0.18   2000   1000   383.4   1
p2se18   12.5   12   7.69   5   7   6.5   0.15   -   0.38   400   438   375.39   1   v12s34   29   10.4   10.4   22   22   22   0.63   -   -   1570   688   688   1
p2sr   11   -   5.1   4.5   -   1.22   0.18   0.25   0.25   320   -   352.85   1   v12s35   19   10   4.48   25   11.5   3.88   0.82   -   0.11   2000   1000   445.6   1
p2sw1   13   -   -   9.5   -   5   0.18   0.25   0.25   1300   -   -   1   v12s36   25   5   1.94   25   11.5   2.29   0.82   -   0.04   2000   1000   111.68   1
p2sw2   13   -   4.51   9.5   -   3.55   0.18   0.25   0.09   1300   -   244.92   1   v12s37   23.5   15.5   10.84   25   11.5   10   0.82   -   0.22   2000   1000   625.68   1
p2sw3   11   -   -   9.5   -   5   0.18   0.25   0.25   1300   -   -   1   vc1   39   -   25.5   30   30   19.23   6.2   2.7   0.7   2000   1000   648.23   1
p2sw4   7.8   -   -   4.5   -   -   0.18   0.25   0.25   320   -   -   1   vc1a   39   -   37.54   6.5   -   6.55   6.2   2.7   1   420   490   243.21   1
p2sw5   7.8   -   2.31   9.5   -   6.48   0.18   0.25   0.04   1300   -   395.17   1   vc1b   38   31   24.57   6.5   -   13.79   6.2   2.7   1.93   420   490   343.51   1
p2sw6   11   -   -   9.5   -   5   0.18   0.25   0.25   1300   -   -   1   vc1c   49.5   39.5   10.04   6.5   -   0.05   1.6   1.3   0.14   420   490   25.55   1
p2sw7   11   -   -   4.5   -   -   0.18   0.25   0.25   320   -   -   1   vc21   49.5   39.5   22.02   30   20   16.67   1.6   1.3   0.16   2000   1200   655.79   1
p2sw8   5   -   -   9.5   -   5   0.18   0.25   0.25   1300   -   -   1   vc24   49.5   39.5   39.5   30   20   20   1.6   1.3   1.3   2000   1200   1200   1
p2sw9   2   -   -   4.5   -   -   0.18   0.25   0.25   320   -   -   1   vc26   49.5   39.5   12.96   30   30   14.5   1.6   1.3   0.15   2000   1000   602.01   1
p2sw10   5   -   -   4.5   -   -   0.18   0.25   0.25   320   -   -   1   vc214   38   31   20.51   6.5   -   10.08   1.6   1.3   1.3   420   490   288.8   1
p2sw11   2   -   -   4.5   -   -   0.18   0.25   0.25   320   -   -   1   vc215   21   32   31.62   25   18   17   1.4   -   2.23   844   570   508.95   1
p2sw12   2   -   0.88   4.5   -   0.92   0.18   0.25   0.23   320   -   242.23   1   vc216   -   23   17.56   -   15.5   2.66   -   -   1.33   -   220   101.68   1
p2sw13   5   -   -   9.5   -   5   0.18   0.25   0.25   1300   -   -   1   vc217   -   23   22   -   15.5   10.31   -   -   1.4   -   220   220   1
p2sw14   5   -   -   4.5   -   -   0.18   0.25   0.25   320   -   -   1   vc222   38.5   37   37   15   15   12   1.6   1.3   1.3   1600   1800   1800   1
p2sw15   5   -   -   9.5   -   5   0.18   0.25   0.25   1300   -   -   1   vc224   38.5   37   37   30   30   30   1.6   1.3   1.3   2000   1000   1000   1
p2sw16   13   -   -   4.5   -   -   0.18   0.25   0.25   320   -   -   1   vc2922   34.5   16.5   16.5   30   20   20   1.6   1.3   1.3   2000   1200   1200   1
p2sw17   7.8   -   -   4.5   -   -   0.18   0.25   0.25   320   -   -   1   vc31   49.5   39.5   17.14   30   20   7.49   1.6   1.3   0.26   2000   1200   507.55   1
p2sw18   7.8   -   -   4.5   -   -   0.18   0.25   0.25   320   -   -   1   vc32   34.5   16.5   16.5   30   30   30   1.6   1.3   1.3   2000   1000   1000   1
p2sw19   2   -   -   4.5   -   -   0.18   0.25   0.25   320   -   -   1   vc33   34.5   16.5   16.5   30   20   20   1.6   1.3   1.3   2000   1200   1200   1
p2sw20   2   -   -   9.5   -   5   0.18   0.25   0.25   1300   -   -   1   vc34   34.5   16.5   16.5   6.5   -   -   1.6   1.3   1.3   420   490   480   1
p2sw21   2   -   -   4.5   -   -   0.18   0.25   0.25   320   -   -   1   vc35   49.5   39.5   39.5   30   20   20   1.6   1.3   1.3   2000   1200   1200   1
p2sw22   7.8   -   -   4.5   -   -   0.18   0.25   0.25   320   -   -   1   vcn32   38   31   31   15   15   12   6.2   2.7   2.7   1600   1800   1800   1
p2sw23   2   -   -   4.5   -   -   0.18   0.25   0.25   320   -   -   1   vcn324   38.5   37   37   15   15   12   1.7   1.1   1.1   1600   1800   1800   1
p2sw24   11   -   -   4.5   -   -   0.18   0.25   0.25   320   -   -   1   vcn327   38   31   31   6.5   -   -   1.7   1.1   1.1   420   490   480   1
p2sw25   2   -   -   4.5   -   -   0.18   0.25   0.25   320   -   -   1   vcn3e1   38.5   37   9.48   15   15   2.64   1.7   1.1   0.51   1600   1800   112.15   1
p2sw26   5   -   -   4.5   -   -   0.18   0.25   0.25   320   -   -   1   vcn3e3   38.5   37   6.84   15   15   0.84   1.6   1.3   0.41   1600   1800   32.81   1
p2sw27   5   -   -   4.5   -   -   0.18   0.25   0.25   320   -   -   1   vcn3e6   38   31   31   15   15   12   1.6   1.3   1.3   1600   1800   1800   1
p2sw28   2   -   -   4.5   -   -   0.18   0.25   0.25   320   -   -   1   vcn3e8   41.5   -   -   1.5   -   -   -   -   -   400   -   -   1
p2sw29   2   -   -   4.5   -   -   0.18   0.25   0.25   320   -   -   1   vcn3w1   38.5   37   37   6.5   -   -   1.6   1.3   1.3   420   490   480   1
por9a   30   37   37   0.25   3   3   3.5   1.8   1.8   400   150   150   1   vcn3w2   38.5   37   37   6.5   -   -   1.7   1.1   1.1   420   490   480   1
por9b   30   37   37   0.25   3   3   3.5   1.8   1.8   400   150   150   1   vcn3w4   38.5   37   37   6.5   -   -   1.6   1.3   1.3   420   490   480   1
por9c   41   -   -   0.3   0.1   0.1   -   -   -   57   61.5   58   1   vcn3w5   49.5   39.5   39.5   6.5   -   -   1.6   1.3   1.3   420   490   480   1
por9e   41   -   -   5.5   -   -   5   -   -   450   47.4   47.4   1   vcn3w6   38.5   37   37   6.5   -   -   1.6   1.3   1.3   420   490   480   1
por9f   24   9.5   9.06   5.5   -   0.67   -   -   1.21   450   47.4   28.02   1   vcn3w8   38.5   37   37   6.5   -   -   1.7   1.1   1.1   420   490   480   1
por9g   24   9.5   5.98   0.3   0.1   0.01   5   -   0.41   57   61.5   2.02   1   vcn3w9   34.5   16.5   16.5   6.5   -   -   6.2   2.7   2.7   420   490   480   1
por9h   24   9.5   6.79   0.3   0.1   0.07   5   -   0.56   57   61.5   39.5   1   cn3ei1   38.6   36.5   20.98   7   10   8   1.9   -   0.89   400   900   297.74   1
por9i   24   9.5   8.25   0.3   0.1   0.08   5   -   0.78   57   61.5   37.64   1   cn3ei2   38.6   36.5   0.39   7   10   -   1.9   -   3.62   400   900   35.46   1
por9j   41   -   1.81   5.5   -   0.96   5   -   0.16   450   47.4   47   1   vcarmn   38   31   25.68   30   30   13.98   1.7   1.1   0.31   2000   1000   683.22   1
por9l   41   -   17.69   5.5   -   0.05   5   -   0.4   450   47.4   13.44   1   vcn12   39   -   21.13   15   15   8.6   6.2   2.7   0.8   1600   1800   315.62   1
por9m   30   37   7.82   0.25   3   0.1   3.5   1.8   0.56   400   150   39.03   1   vcn13   38   31   20.6   30   30   10   1.7   1.1   0.23   2000   1000   317.57   1
por9n   24   9.5   9.5   0.3   0.1   0.1   -   -   -   57   61.5   58   1   vcn14   39   -   22.24   30   20   11.01   1.7   1.1   0.39   2000   1200   363.6   1
por9o   34   24   8.49   1.3   2   0.15   4.4   2.7   0.88   580   160   31.34   1   vcn15   -   -   -   30   20   20   1.7   1.1   1.1   2000   1200   1200   1
por9p   37   36   16.43   1.3   2   0.89   4.4   2.7   0.78   580   160   84.1   1   vcn16   -   -   -   30   30   30   6.2   2.7   2.7   2000   1000   1000   1
por9q   37   36   1.71   1.3   2   0.17   4.4   2.7   0.05   580   160   20.31   1   vcn17   39   -   -   6.5   -   -   1.7   1.1   1.1   420   490   480   1
por9r   34   24   7.04   6   12   0.11   4.4   2.7   0.74   900   1100   84.94   1   vcn18   39   -   -   6.5   -   -   1.7   1.1   1.1   420   490   480   1
por9s   34   24   24   6   12   11   4.4   2.7   2.7   900   1100   1100   1   vcn4i   29   36   16.31   0.3   4   1.31   5   2.5   0.51   300   400   87.4   1

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-26

 

 

Domain   ZN_D   ZN_C   ZN_C3   PB_D   PB_C   PB_C3   CU_D   CU_C   CU_C3   AG_D   AG_C   AG_C3   Grade   Domain   ZN_D   ZN_C   ZN_C3   PB_D   PB_C   PB_C3   CU_D   CU_C   CU_C3   AG_D   AG_C   AG_C3   Grade
Ore Body   (%)   (%)   (%)   (%)   (%)   (%)   (%)   (%)   (%)   (g/t)   (g/t)   (g/t)   Domain   Ore Body   (%)   (%)   (%)   (%)   (%)   (%)   (%)   (%)   (%)   (g/t)   (g/t)   (g/t)   Domain
por9t   34   24   24   1.3   2   1   5   -   -   580   160   150   1   vcn41   17.5   17   11.37   8   10   7.78   -   -   0.14   2580   1500   776.78   1
por9u   34   24   24   6   12   11   4.4   2.7   2.7   900   1100   1100   1   vcn42   17.5   17   17   8   10   9   -   -   -   2580   1500   1500   1
por9v   37   -   -   6   12   11   4.4   2.7   2.7   900   1100   1100   1   vcn43   17.5   17   17   8   10   9   -   -   -   2580   1500   1500   1
por9w   37   -   -   6   12   11   4.4   2.7   2.7   900   1100   1100   1   vcn44   17.5   17   17   8   10   9   -   -   -   2580   1500   1500   1
por9x   34   24   24   6   12   11   4.4   2.7   2.7   900   1100   1100   1   vcn45   17.5   17   17   8   10   9   -   -   -   2580   1500   1500   1
por9y   34   24   24   1.3   2   1   5   -   -   580   160   150   1   vcn46   -   30   22   22   22   15   2.3   1.5   0.8   1570   688   418.34   1
por9z   34   24   24   1.3   2   1   4.4   2.7   2.7   580   160   150   1   vpor31   21   -   -   9   0.08   0.08   1   -   -   825   -   -   1
por91   37   36   36   1.3   2   1   4.4   2.7   2.7   580   160   150   1   vpor32   7   -   1.11   20   37   1.09   0.25   0.26   -   420   1922   45.82   1
por92   34   24   5.92   1.3   2   0.05   5   -   1.65   580   160   33.16   1   vpor33   21   -   -   9   0.08   0.08   1   -   -   825   -   -   1
por93   34   24   24   1.3   2   1   4.4   2.7   2.7   580   160   150   1   vpor34   7   -   -   20   37   12   0.25   0.26   0.26   420   1922   1922   1
por94   34   24   24   1.3   2   1   4.4   2.7   2.7   580   160   150   1   vpor35   21   -   0.14   9   0.08   0.08   1   -   0.74   825   -   188.33   1
por95   34   24   3.51   1.3   2   0.09   5   -   0.75   580   160   30.23   1   vpor36   15.5   -   -   15.5   -   -   1.8   -   -   400   -   -   1
por96   37   36   17.05   6   12   1.04   4.4   2.7   0.4   900   1100   72.25   1   vpor37   15.5   -   -   15.5   -   -   1.8   -   -   400   -   -   1
por97   34   24   16.1   6   12   0.31   4.4   2.7   0.49   900   1100   73.4   1   vpor38   15.5   -   -   15.5   -   -   1.8   -   -   400   -   -   1
por98   37   36   1.5   6   12   0.22   4.4   2.7   0.16   900   1100   11.63   1   vprg   27   37   19   2   9   5.8   4   4.3   1.12   400   1200   236.39   1
porv9a   37   36   20.28   6   12   4.04   4.4   2.7   0.58   900   1100   158.19   1   vprg1   27   37   24.07   2   9   4.27   4   4.3   0.5   400   1200   180.77   1
porv9e   30   37   16.85   2   10   8.06   3.5   1.8   0.9   120   300   280.4   1   vprg2   39   -   24.14   30   30   12   6.2   2.7   0.72   2000   1000   741.34   1
porv9f   30   37   37   0.25   3   3   3.5   1.8   1.8   400   150   150   1   vprg3   1.5   -   2.87   2   9   0.02   4   4.3   2.04   400   1200   24.71   1
porv9w   37   -   -   6   12   11   4.4   2.7   2.7   900   1100   1100   1   vprg4   27   37   37   2   9           4.3   4.3   400   1200   1200   1
porv9x   34   24   6.6   6   12   4.45   4.4   2.7   0.22   900   1100   279.85   1   vprg5   1.5   -   -   2   9           4.3   4.3   400   1200   1200   1
sara1   12   -   -   22   28   28   0.45   -   -   2000   3000   3000   1   vprg6   27   37   15.85   2   9           4.3   0.3   400   1200   306.37   1
sara2   29   39   39   22   28   28   0.45   -   -   2000   3000   3000   1   vprgb   24   15   8.02   14.4   12   2.84   -   1.5   0.42   1400   850   134.44   1
sara3   12   -   -   22   28   28   0.45   -   -   2000   3000   3000   1   vprgb1   30   16.5   12.04   0.9   10   3.5   1.6   -   0.54   435   179   156.25   1
sara4   12   -   -   22   28   28   0.45   -   -   2000   3000   3000   1   vprgb2   26   13   12   20   13   12   2   -   0.92   800   400   331.19   1
sara5   12   -   -   22   28   28   0.45   -   -   2000   3000   3000   1   vprgb3   26.5   30   15.93   27.5   22   16.5   -   0.3   0.25   1070   -   1363.78   1
sara6   12   -   -   22   28   28   0.45   -   -   2000   3000   3000   1   vprgb4   26   13   12   20   13   6   2   -   -   800   400   400   1
saras1   4.5   -   -   3.8   -   -   -       -   200   -   -   1   vprgb5   26   13   12   20   13   6   2   -   -   800   400   400   1
saras2   10.5   12   12   4   5.3   5.3   -   -   -   586   375   375   1   vprgb6   21   8   8   12   9.5   9.5   2   -   -   890   500   500   1
saras3   4.5   -   -   3.8   -   -   -       -   200   -   -   1   vprgb7   24   15   15   14.4   12   12   -   0.3   0.2   1400   850   850   1
saras4   4.5   -   -   3.8   -   -   -       -   200   -   -   1   vprgb8   26   13   12   20   13   6   -   -   -   800   400   400   1
saras5   4.5   -   -   3.8   -   -   -       -   200   -   -   1   vprgb9   26   13   12   20   13   6   -   -   -   800   400   400   1
saras6   4.5   -   -   3.8   -   -   -       -   200   -   -   1   vprgba   26.5   30   12.55   27.5   22   15.88   -   0.3   0.21   1070   -   688.2   1
soc21   38.5   37   17.02   15   15   14   1.6   1.3   0.27   1600   1800   860.57   1   vprgbb   26.5   30   26.5   27.5   22   20   -   0.3   0.23   1070   -   958.75   1
soc22   38.5   37   9.13   15   15   7.7   1.6   1.3   0.21   1600   1800   727.67   1   vr   -   -       30   -   -   -       -   1600   -   -   1
soc23   49.5   39.5   20.32   6.5   -   4.52   1.6   1.3   0.2   420   490   225.25   1   vr1   -   -       30   -   -   -       -   1600   -   -   1
soc24   34.5   16.5   8.22   30   20   8.99   1.6   1.3   0.12   2000   1200   752.39   1   por9cf1   40   20   15   5   0.2   0.15   2   0.7   0.5   300   60   40   1
soc25   49.5   39.5   39.5   6.5   -   -   1.6   1.3   1.3   420   490   480   1   por9cf2   40   20   15   5   0.2   0.15   2   0.7   0.5   300   60   40   1
soc27   38.5   37   37   30   20   20   1.7   1.1   1.1   2000   1200   1200   1   por9cf3   40   20   15   5   0.2   0.15   2   0.7   0.5   300   60   40   1
soc28   49.5   39.5   39.5   15   15   12   1.6   1.3   1.3   1600   1800   1800   1   por9cf4   40   20   15   5   0.2   0.15   2   0.7   0.5   300   60   40   1
soc29   34.5   16.5   16.5   6.5   -   -   1.6   1.3   1.3   420   490   480   1   por9cf5   40   20   15   5   0.2   0.15   2   0.7   0.5   300   60   40   1
soc41   32   10.8   4.99   15   15   3.62   -   -   0.08   1250   750   180.17   1   por9cf6   40   20   15   5   0.2   0.15   2   0.7   0.5   300   60   40   1
soc42   32   10.8   1.71   15   15   4.23   -   -   0.09   1250   750   156.33   1   por9cf7   40   20   15   5   0.2   0.15   2   0.7   0.5   300   60   40   1
soc43   32   10.8   6.11   15   15   5.29   -   -   0.12   1250   750   410.69   1   por9cf8   40   20   15   5   0.2   0.15   2   0.7   0.5   300   60   40   1
soc44   32   10.8   10.8   11.5   -   -   -   -   -   1130   -   -   1   por9   17   9   8   -   -   -       -               -   1
soc45   17   2   1.88   15   15   2.99   -   -   0.09   1250   750   127.45   1   por9   22   27   20   -   -   -       -               -   2
soc46   17   2   2   11.5   -   -   -   -   -   1130   -   -   1   por9   -   -   -   2.5   1.5   1   2.5   1.5   1   140   88   70   1
soc47   17   2   2   11.5   -   -   -   -   -   1130   -   -   1   vcn3   -   -   -               0.9   0.4   0.3   -   -   -   1
soc48   17   2   0.38   15   15   0.24   -   -   0.03   1250   750   147.21   1   vcn3   -   -   -               2   1.2   1   -   -   -   2
soc49   32   10.8   10.8   11.5   -   -   -   -   -   1130   -   -   1   vcn3   35   22   20   19   11   9               1000   510   490   1
soc210   34.5   16.5   16.5   6.5   -   -   1.6   1.3   1.3   420   490   480   1   v5ne1   15   20   17   -   -   -       -               -   1
soc211   38.5   37   37   15   15   12   1.6   1.3   1.3   1600   1800   1800   1   v5ne1   19   15   11   -   -   -       -               -   2
soc212   34.5   16.5   16.5   15   15   12   1.6   1.3   1.3   1600   1800   1800   1   v5ne1   -   -   -   15   12   -   2   1.2   -   700   600   500   1
soc213   34.5   16.5   16.5   6.5   -   -   1.6   1.3   1.3   420   490   480   1   v12i1   30   -   35   -   -       6   1.6   1.2   -   -   -   1
soc214   38   31   31   15   15   12   1.6   1.3   1.3   1600   1800   1800   1   v12i1   -   -       2   8   1   -   -   -       600   500   1
soc410   17   2   2   15   15   8   -   -   -   1250   750   750   1   v12i1   -   -   -   0.5   2.8   1   -   -   -   100   200   190   2
soc411   32   10.8   10.8   11.5   -   -   -   -   -   1130   -   -   1                                                        

 

Note:

1. C:Capping levels fo Channels, D: Capping levels for drill holes, C3: Capping levels for Channels for third pass interpolation.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-27

 

 

Table 11-9:                 Estimation Domain Capped and Raw Assay Statistics for Zinc (Zn %)

Nexa Resources S.A. – El Porvenir Mine

 

     

Raw Assay

Capped Raw Assay

C_ESTIM

 C_Hole

# Samples

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

1 1 3196 0.00 50.86 10.48 8.99 0.86 0.00 50.86 10.48 8.99 0.86
1 2 2009 0.00 40.84 3.54 6.60 1.86 0.00 39.00 3.54 6.59 1.86
21 1 179 0.02 36.55 4.80 6.93 1.44 0.02 20.00 4.47 5.85 1.31
21 2 799 0.00 49.05 4.61 7.02 1.52 0.00 40.00 4.58 6.86 1.50
100 1 469 0.00 54.63 4.00 6.78 1.69 0.00 39.50 3.97 6.57 1.66
100 2 2227 0.00 49.81 4.65 7.63 1.64 0.00 49.50 4.65 7.63 1.64
154 1 1139 0.00 37.33 6.06 7.54 1.25 0.00 31.00 6.04 7.48 1.24
154 2 1776 0.00 46.56 6.15 7.76 1.26 0.00 38.00 6.13 7.70 1.26
157 1 77 0.04 31.30 10.78 8.06 0.75 0.04 23.00 10.60 7.72 0.73
201 2 24 0.00 14.98 2.00 3.77 1.89 0.00 14.98 2.00 3.77 1.89
250 1 205 0.06 42.96 8.12 8.02 0.99 0.06 32.00 8.01 7.62 0.95
250 2 39 0.00 30.65 8.70 7.59 0.87 0.00 21.00 8.35 6.76 0.81
256 1 9 0.11 13.91 7.28 4.94 0.68 0.11 13.91 7.28 4.94 0.68
256 2 273 0.00 25.64 2.51 4.17 1.66 0.00 21.00 2.48 4.03 1.63
259 1 2236 0.00 50.00 8.07 6.86 0.85 0.00 50.00 8.07 6.86 0.85
259 2 673 0.00 40.06 4.26 6.55 1.54 0.00 30.00 4.22 6.33 1.50
264 2 184 0.00 37.83 5.67 6.19 1.09 0.00 33.00 5.66 6.16 1.09
270 1 26 0.07 23.20 4.39 5.50 1.25 0.07 23.20 4.39 5.50 1.25
270 2 168 0.00 31.92 5.19 6.82 1.31 0.00 31.00 5.19 6.80 1.31
302 1 23 0.02 7.71 0.56 1.63 2.90 0.02 7.71 0.56 1.63 2.90
302 2 170 0.00 10.41 0.53 1.19 2.24 0.00 1.50 0.38 0.51 1.35
306 1 65 0.12 20.86 2.07 3.08 1.49 0.12 15.00 2.02 2.79 1.38
306 2 509 0.00 28.06 2.02 4.14 2.04 0.00 24.00 2.02 4.09 2.03
307 1 5574 0.00 53.65 6.95 6.79 0.98 0.00 37.00 6.95 6.77 0.97
307 2 4169 0.00 40.46 2.20 4.09 1.86 0.00 27.00 2.19 4.03 1.84
350 1 69 0.00 20.60 6.30 5.55 0.88 0.00 20.60 6.30 5.55 0.88
350 2 346 0.00 32.86 4.47 5.64 1.26 0.00 30.00 4.46 5.61 1.26
453 1 31 0.02 24.87 5.44 6.43 1.18 0.02 24.87 5.44 6.43 1.18
453 2 161 0.00 43.79 3.33 7.30 2.19 0.00 41.00 3.31 7.22 2.18
458 1 91 0.01 10.76 2.50 2.72 1.09 0.01 9.50 2.49 2.70 1.09
458 2 415 0.00 27.40 3.47 3.57 1.03 0.00 24.00 3.47 3.55 1.02
466 1 1086 0.00 38.18 4.77 6.10 1.28 0.00 36.00 4.77 6.09 1.28
466 2 2615 0.00 42.38 4.23 6.28 1.49 0.00 37.00 4.23 6.27 1.48
550 1 1 14.73 14.73 14.73 - - 14.73 14.73 14.73 - -
550 2 1063 0.00 41.45 3.05 5.98 1.96 0.00 37.00 3.05 5.94 1.95
600 1 2274 0.00 35.28 1.94 2.79 1.44 0.00 24.00 1.94 2.73 1.41

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-28

 

 

     

Raw Assay

Capped Raw Assay

C_ESTIM

 C_Hole

# Samples

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

600 2 1859 0.00 45.40 2.45 4.40 1.80 0.00 34.00 2.44 4.33 1.77
652 1 9 0.02 0.93 0.43 0.30 0.69 0.02 0.93 0.43 0.30 0.69
652 2 494 0.00 14.77 0.27 0.70 2.64 0.00 2.00 0.23 0.43 1.89
671 1 19 0.04 5.02 1.25 1.39 1.12 0.04 5.02 1.25 1.39 1.12
671 2 378 0.00 14.44 0.66 1.30 1.97 0.00 13.00 0.66 1.26 1.93
674 1 10 0.02 3.45 0.51 1.07 2.12 0.02 3.45 0.51 1.07 2.12
674 2 182 0.00 7.88 0.59 1.20 2.02 0.00 7.80 0.59 1.19 2.01
677 2 354 0.00 6.39 0.45 0.76 1.67 0.00 5.00 0.45 0.74 1.65
700 1 272 0.04 43.07 6.77 10.46 1.55 0.04 42.50 6.76 10.45 1.54
700 2 241 0.00 45.78 3.53 6.24 1.77 0.00 31.00 3.44 5.73 1.67
701 1 590 0.00 44.23 4.07 5.96 1.46 0.00 39.00 4.06 5.91 1.45
701 2 828 0.00 35.00 2.08 4.00 1.92 0.00 29.00 2.07 3.93 1.89
750 1 11 0.04 3.69 0.57 1.24 2.17 0.04 3.69 0.57 1.24 2.17
750 2 1266 0.00 24.10 1.57 2.47 1.57 0.00 21.00 1.57 2.42 1.55
751 1 8 0.01 1.33 0.50 0.39 0.77 0.01 1.33 0.50 0.39 0.77
751 2 135 0.00 7.26 1.40 1.34 0.96 0.00 7.00 1.39 1.33 0.95
756 2 225 0.00 20.02 1.15 2.03 1.76 0.00 15.50 1.14 1.97 1.72
800 1 46 0.02 3.88 0.50 0.76 1.51 0.02 3.88 0.50 0.76 1.51
800 2 60 0.00 18.37 1.62 3.44 2.12 0.00 8.00 1.34 2.29 1.71
850 2 97 0.00 32.36 4.98 7.09 1.42 0.00 30.00 4.96 6.98 1.41
860 1 12 0.26 13.83 3.15 3.82 1.21 0.26 13.83 3.15 3.82 1.21
860 2 146 0.00 32.73 2.25 3.60 1.60 0.00 18.00 2.20 3.28 1.49
865 2 103 0.00 33.02 5.55 6.90 1.24 0.00 27.00 5.51 6.77 1.23
872 2 111 0.00 16.54 2.03 3.01 1.49 0.00 14.50 2.02 2.98 1.48
883 1 11 1.92 21.91 5.53 3.55 0.64 1.92 21.91 5.53 3.55 0.64
883 2 38 0.12 19.97 5.70 5.23 0.92 0.12 18.50 5.68 5.18 0.91
901 1 134 0.01 13.66 2.51 2.63 1.05 0.01 12.50 2.50 2.59 1.04
901 2 550 0.00 34.36 3.78 4.75 1.26 0.00 26.50 3.77 4.70 1.25
908 2 245 0.00 30.81 2.31 3.69 1.60 0.00 21.00 2.28 3.47 1.52
950 1 22 0.30 17.70 5.86 5.33 0.91 0.30 17.00 5.81 5.24 0.90
950 2 283 0.00 34.92 3.88 6.28 1.62 0.00 33.00 3.87 6.23 1.61
1008 1 9 0.04 26.07 4.36 8.66 1.99 0.04 26.07 4.36 8.66 1.99
1008 2 237 0.00 23.92 1.55 3.55 2.29 0.00 23.00 1.54 3.51 2.28
1016 1 72 0.08 14.20 1.10 1.72 1.57 0.08 5.00 1.00 1.15 1.15
1016 2 199 0.00 29.96 3.55 5.61 1.58 0.00 25.00 3.50 5.41 1.55
1019 2 182 0.00 27.07 2.38 3.78 1.59 0.00 24.00 2.37 3.72 1.57
1026 1 195 0.03 12.24 1.32 1.73 1.31 0.03 10.00 1.31 1.66 1.27
1026 2 634 0.00 22.94 1.62 2.79 1.72 0.00 19.00 1.61 2.74 1.70
1028 1 188 0.02 19.46 2.24 2.89 1.29 0.02 15.50 2.23 2.84 1.27

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-29

 

 

     

Raw Assay

Capped Raw Assay

C_ESTIM

 C_Hole

# Samples

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

1028 2 1876 0.00 25.51 2.04 2.60 1.27 0.00 23.50 2.04 2.60 1.27
1029 1 25 0.51 44.59 3.12 5.44 1.74 0.51 10.80 2.64 2.41 0.91
1029 2 300 0.00 33.23 2.96 3.86 1.31 0.00 25.00 2.93 3.66 1.25
1034 1 15 0.03 1.61 0.42 0.51 1.23 0.03 1.61 0.42 0.51 1.23
1034 2 302 0.00 34.83 1.83 3.72 2.03 0.00 25.50 1.82 3.65 2.00
1054 1 1 4.12 4.12 4.12 - - 4.12 4.12 4.12 - -
1054 2 16 0.05 27.87 13.78 11.09 0.80 0.05 27.87 13.78 11.09 0.80
1151 1 1042 0.01 40.07 5.30 5.65 1.06 0.01 22.00 5.20 5.25 1.01
1151 2 3355 0.00 47.10 5.04 6.06 1.20 0.00 35.00 5.03 6.00 1.19
1208 2 118 0.00 47.80 6.63 9.09 1.37 0.00 41.50 6.56 8.78 1.34
1300 1 1333 0.00 41.28 7.79 6.84 0.88 0.00 36.50 7.78 6.81 0.88
1300 2 984 0.00 47.61 3.98 6.57 1.65 0.00 38.60 3.97 6.53 1.64
1350 1 49 1.55 30.30 13.34 6.01 0.45 1.55 24.50 13.22 5.71 0.43
1350 2 1508 0.00 28.24 4.82 4.79 0.99 0.00 27.50 4.82 4.79 0.99
1402 1 89 0.21 15.45 4.55 2.71 0.60 0.21 13.00 4.54 2.67 0.59
1402 2 2471 0.00 38.40 3.57 3.94 1.10 0.00 31.00 3.57 3.93 1.10
1408 2 460 0.00 22.55 3.32 3.69 1.11 0.00 19.00 3.31 3.61 1.09
1410 2 427 0.00 19.02 2.08 2.91 1.40 0.00 17.00 2.08 2.88 1.38
1450 1 129 0.02 11.72 1.57 2.28 1.45 0.02 8.00 1.50 2.01 1.34
1450 2 214 0.00 23.38 2.35 3.34 1.42 0.00 21.00 2.33 3.26 1.40
1452 1 81 0.00 20.72 1.94 4.07 2.10 0.00 13.00 1.73 3.27 1.89
1452 2 193 0.00 32.56 3.74 5.38 1.44 0.00 26.00 3.71 5.22 1.41
1458 1 334 0.00 34.48 3.98 6.20 1.56 0.00 30.00 3.95 6.08 1.54
1458 2 291 0.00 32.95 2.70 4.51 1.67 0.00 26.50 2.67 4.34 1.63
1504 1 113 0.01 21.48 1.71 3.14 1.84 0.01 15.50 1.65 2.83 1.71
1504 2 400 0.01 38.64 2.72 5.74 2.11 0.01 23.00 2.63 5.36 2.03
1555 1 907 0.01 38.44 2.94 4.84 1.64 0.01 37.00 2.94 4.83 1.64
1555 2 2121 0.00 55.23 3.12 5.26 1.69 0.00 38.50 3.11 5.21 1.67
1558 1 158 0.01 30.50 1.54 3.37 2.19 0.01 16.50 1.46 2.77 1.90
1558 2 905 0.00 37.41 1.71 3.81 2.23 0.00 34.50 1.71 3.79 2.22
1607 1 280 0.00 14.64 0.85 1.78 2.09 0.00 10.80 0.85 1.75 2.06
1607 2 785 0.00 34.25 1.56 3.46 2.21 0.00 32.00 1.56 3.43 2.20
1609 1 27 0.03 2.47 0.60 0.69 1.16 0.03 2.00 0.58 0.65 1.12
1609 2 306 0.00 21.61 0.94 2.27 2.41 0.00 17.00 0.93 2.17 2.33
1614 1 13 0.04 9.67 1.90 1.90 1.00 0.04 9.67 1.90 1.90 1.00
1614 2 118 0.00 34.11 3.31 5.80 1.75 0.00 23.00 3.18 5.22 1.64
1650 1 2089 0.00 41.38 7.36 6.45 0.88 0.00 36.00 7.35 6.43 0.87
1650 2 1281 0.00 37.30 3.28 5.15 1.57 0.00 29.00 3.27 5.07 1.55
1702 1 169 0.03 23.81 2.86 3.93 1.38 0.03 17.00 2.82 3.76 1.33

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-30

 

 

     

Raw Assay

Capped Raw Assay

C_ESTIM

 C_Hole

# Samples

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

1702 2 264 0.00 48.23 3.14 5.23 1.67 0.00 36.00 3.12 5.11 1.64
1712 1 37 0.02 23.80 2.75 5.16 1.87 0.02 15.50 2.48 4.14 1.67
1712 2 186 0.00 26.97 2.53 4.90 1.94 0.00 23.50 2.52 4.83 1.92
1714 1 44 0.20 16.71 3.46 3.45 1.00 0.20 13.50 3.39 3.21 0.95
1714 2 222 0.00 35.84 5.49 7.40 1.35 0.00 33.00 5.49 7.37 1.34
1718 1 85 0.02 18.49 3.40 3.93 1.16 0.02 14.50 3.32 3.68 1.11
1718 2 73 0.00 18.25 1.46 3.38 2.32 0.00 13.00 1.41 3.18 2.26
1754 1 41 0.29 15.10 3.27 3.37 1.03 0.29 10.40 3.20 3.17 0.99
1754 2 860 0.00 43.26 2.57 3.90 1.52 0.00 29.00 2.56 3.85 1.50
1755 2 5 0.44 15.79 5.92 6.47 1.09 0.44 15.79 5.92 6.47 1.09
1850 1 312 0.01 22.49 2.29 3.80 1.66 0.01 17.00 2.27 3.70 1.63
1850 2 800 0.00 44.47 1.22 2.96 2.42 0.00 17.50 1.18 2.63 2.22
1855 1 329 0.00 31.40 10.32 7.77 0.75 0.00 30.00 10.31 7.75 0.75
1855 2 141 0.00 22.20 4.26 7.01 1.65 0.00 22.20 4.26 7.01 1.65
1900 1 1225 0.00 24.87 4.49 4.87 1.09 0.00 24.87 4.49 4.87 1.09
1900 2 705 0.00 19.67 2.49 3.14 1.26 0.00 17.50 2.48 3.12 1.26
1950 1 220 0.01 18.68 2.02 2.59 1.29 0.01 12.00 1.97 2.34 1.19
1950 2 227 0.00 13.97 1.35 2.11 1.56 0.00 10.50 1.34 2.01 1.51
1959 1 512 0.00 13.77 1.61 1.81 1.12 0.00 9.50 1.60 1.73 1.09
1959 2 317 0.00 24.28 1.49 2.47 1.65 0.00 20.00 1.48 2.38 1.61
1965 1 216 0.02 14.12 1.81 2.34 1.29 0.02 12.00 1.80 2.28 1.27
1965 2 288 0.00 23.85 1.06 2.21 2.09 0.00 12.50 1.02 1.91 1.87
2000 1 17 0.09 5.78 1.76 1.77 1.00 0.09 5.78 1.76 1.77 1.00
2000 2 290 0.00 14.74 1.42 1.64 1.15 0.00 11.00 1.41 1.53 1.08
2051 2 388 0.00 19.93 1.52 2.23 1.46 0.00 16.50 1.52 2.20 1.45
2060 2 488 0.00 31.67 1.84 3.38 1.83 0.00 28.00 1.84 3.31 1.80
2065 2 71 0.00 34.19 4.40 5.04 1.14 0.00 20.00 4.32 4.69 1.08
2067 2 22 0.01 25.31 2.98 5.53 1.85 0.01 14.00 2.44 3.50 1.43
2072 2 22 0.00 14.12 1.82 3.14 1.72 0.00 9.00 1.66 2.57 1.55
2073 2 12 0.16 4.59 2.06 1.42 0.69 0.16 4.50 2.06 1.42 0.69
2079 2 19 0.01 11.15 3.98 2.50 0.63 0.01 7.50 3.89 2.30 0.59
2100 1 75 0.04 21.24 2.04 3.45 1.69 0.04 16.50 2.00 3.25 1.63
2100 2 281 0.00 32.32 2.08 2.81 1.35 0.00 30.00 2.07 2.77 1.34
2104 2 226 0.02 28.60 2.60 4.13 1.59 0.02 26.00 2.60 4.10 1.58
2150 2 829 0.00 15.05 0.82 1.53 1.86 0.00 12.00 0.82 1.51 1.84
2156 1 1 0.72 0.72 0.72 - - 0.72 0.72 0.72 - -
2156 2 103 0.01 5.23 0.78 0.97 1.25 0.01 4.50 0.77 0.95 1.23
4501 1 180 0.01 21.75 2.92 3.72 1.27 0.01 9.00 2.62 2.79 1.06
4501 2 325 0.00 24.42 3.65 3.99 1.09 0.00 17.00 3.62 3.84 1.06

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-31

 

 

     

Raw Assay

Capped Raw Assay

C_ESTIM

 C_Hole

# Samples

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

4502 1 693 0.01 52.17 6.49 6.15 0.95 0.01 27.00 6.38 5.62 0.88
4502 2 540 0.00 30.13 5.81 5.26 0.91 0.00 22.00 5.76 5.11 0.89
17501 1 191 0.01 30.30 8.51 7.87 0.93 0.01 20.00 8.18 7.25 0.89
17501 2 71 0.00 25.61 6.62 6.96 1.05 0.00 15.00 5.93 5.64 0.95
17502 1 288 0.02 23.75 3.08 4.45 1.45 0.02 15.00 2.97 4.05 1.36
17502 2 336 0.00 27.16 3.77 5.46 1.45 0.00 19.00 3.71 5.25 1.41

 

Note:

C_Hole: 1: Channels, 2: Drill holes

 

Table 11-10:        Estimation Domain Capped and Raw Assay Statistics for Lead (Pb %)

Nexa Resources S.A. – El Porvenir Mine

 

     

Raw Assay

Capped Raw Assay

C_ESTIM

 C_Hole

# Samples

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

1 1 2363 0.00 39.80 6.57 7.12 1.08 0.00 30.00 6.54 7.01 1.07
1 2 2312 0.00 36.65 2.60 5.29 2.04 0.00 30.00 2.59 5.25 2.03
21 1 179 0.01 6.29 0.09 0.56 6.11 0.01 0.20 0.04 0.04 1.17
21 2 799 0.00 26.48 0.14 1.08 7.95 0.00 5.00 0.10 0.41 4.20
100 1 486 0.00 34.43 2.05 4.30 2.10 0.00 20.00 1.97 3.84 1.95
100 2 2181 0.00 39.31 2.71 5.04 1.86 0.00 30.00 2.70 5.00 1.85
154 1 1449 0.00 45.78 1.61 3.99 2.47 0.00 45.78 1.61 3.99 2.47
154 2 2547 0.00 25.93 0.45 2.03 4.50 0.00 6.50 0.33 1.12 3.42
157 1 77 0.01 23.26 1.91 3.82 1.99 0.01 15.50 1.78 3.14 1.76
185 1 34 0.04 37.26 2.74 7.21 2.63 0.04 15.80 1.89 3.28 1.73
185 2 537 0.00 36.24 2.02 3.26 1.62 0.00 18.00 1.98 3.03 1.53
201 2 24 0.00 34.99 4.09 8.26 2.02 0.00 30.00 3.99 7.90 1.98
256 1 9 0.01 1.02 0.20 0.27 1.34 0.01 1.02 0.20 0.27 1.34
256 2 273 0.00 22.71 0.90 2.44 2.72 0.00 13.50 0.86 2.17 2.54
264 2 184 0.00 0.10 0.01 0.01 0.82 0.00 0.10 0.01 0.01 0.82
307 1 5597 0.00 37.60 0.91 2.84 3.11 0.00 9.00 0.75 1.89 2.50
307 2 4339 0.00 20.31 0.17 1.02 6.12 0.00 2.00 0.09 0.31 3.41
308 1 71 0.02 18.16 0.43 1.42 3.32 0.02 10.00 0.41 1.23 3.03
308 2 177 0.00 18.10 0.30 1.54 5.04 0.00 0.90 0.09 0.21 2.33
309 1 57 0.07 19.68 1.51 3.18 2.10 0.07 13.00 1.39 2.56 1.84
309 2 155 0.00 33.77 2.54 4.82 1.90 0.00 20.00 2.44 4.34 1.78
310 1 118 0.00 32.60 5.94 7.80 1.31 0.00 22.00 5.74 7.30 1.27
310 2 105 0.00 32.52 3.07 5.88 1.92 0.00 27.50 3.04 5.74 1.89
350 1 59 0.00 25.50 2.13 4.44 2.09 0.00 10.00 1.76 2.81 1.60

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-32

 

 

     

Raw Assay

Capped Raw Assay

C_ESTIM

 C_Hole

# Samples

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

350 2 197 0.00 7.80 0.36 1.15 3.24 0.00 2.00 0.21 0.51 2.47
450 1 873 0.01 17.17 0.15 0.99 6.46 0.01 1.50 0.07 0.25 3.36
450 2 865 0.00 17.91 0.15 1.07 6.98 0.00 2.50 0.08 0.33 4.04
451 1 10 0.01 0.17 0.03 0.05 1.51 0.01 0.17 0.03 0.05 1.51
451 2 149 0.00 2.36 0.06 0.22 3.82 0.00 0.25 0.03 0.06 1.91
456 1 45 0.00 1.30 0.11 0.26 2.32 0.00 1.30 0.11 0.26 2.32
456 2 195 0.00 27.65 1.11 3.83 3.44 0.00 5.50 0.60 1.47 2.46
458 1 77 0.01 1.07 0.03 0.12 3.89 0.01 0.10 0.02 0.02 1.06
458 2 381 0.00 12.46 0.05 0.43 9.36 0.00 0.30 0.02 0.04 1.63
466 1 1220 0.00 22.59 0.20 1.07 5.33 0.00 2.00 0.12 0.35 2.85
466 2 2793 0.00 32.33 0.17 1.14 6.84 0.00 1.30 0.08 0.22 2.84
600 1 2141 0.00 22.41 1.30 1.96 1.51 0.00 12.00 1.27 1.76 1.38
600 2 2744 0.00 29.00 0.65 2.30 3.51 0.00 6.00 0.48 1.18 2.45
671 1 30 0.02 8.56 1.37 1.96 1.43 0.02 8.56 1.37 1.96 1.43
671 2 767 0.00 30.33 1.17 2.08 1.78 0.00 9.50 1.12 1.71 1.53
700 1 272 0.02 38.66 3.53 5.68 1.61 0.02 20.00 3.47 5.48 1.58
700 2 241 0.00 25.91 2.75 5.22 1.90 0.00 25.91 2.75 5.22 1.90
701 1 590 0.02 35.88 5.15 5.72 1.11 0.02 28.00 5.11 5.54 1.08
701 2 1657 0.00 58.28 2.15 4.36 2.03 0.00 22.00 2.05 3.70 1.81
750 1 11 0.02 7.92 1.12 2.71 2.42 0.02 0.08 0.05 0.02 0.50
750 2 1266 0.00 29.59 0.92 1.90 2.07 0.00 9.00 0.87 1.53 1.76
751 1 54 0.01 43.41 3.64 8.00 2.20 0.01 37.00 3.51 7.38 2.10
751 2 195 0.00 31.43 1.31 1.92 1.47 0.00 20.00 1.29 1.77 1.37
756 2 225 0.00 17.76 0.90 1.72 1.90 0.00 15.50 0.90 1.68 1.86
850 1 12 0.14 5.12 1.57 1.27 0.81 0.14 5.12 1.57 1.27 0.81
850 2 243 0.00 23.32 1.82 3.65 2.01 0.00 19.00 1.79 3.50 1.96
865 2 141 0.00 16.03 1.14 2.53 2.23 0.00 9.00 1.04 2.10 2.02
878 2 73 0.00 5.37 0.38 0.87 2.32 0.00 3.50 0.35 0.74 2.11
883 1 11 1.77 17.22 4.20 2.86 0.68 1.77 17.22 4.20 2.86 0.68
883 2 38 0.00 19.58 3.42 4.66 1.36 0.00 19.58 3.42 4.66 1.36
901 1 134 0.08 16.73 1.66 2.33 1.40 0.08 8.00 1.55 1.80 1.16
901 2 550 0.00 29.01 2.34 3.47 1.48 0.00 16.00 2.27 3.12 1.37
908 2 245 0.00 25.28 2.19 3.31 1.51 0.00 20.00 2.17 3.14 1.45
1028 1 455 0.04 31.87 1.86 3.02 1.63 0.04 11.50 1.73 2.26 1.30
1028 2 2709 0.00 38.29 1.92 2.86 1.49 0.00 25.00 1.91 2.76 1.45
1034 1 30 0.05 20.00 1.47 2.81 1.91 0.05 10.00 1.37 2.25 1.64
1034 2 559 0.00 29.72 1.81 2.89 1.60 0.00 14.00 1.76 2.62 1.49
1151 1 1042 0.00 36.20 0.87 2.67 3.07 0.00 11.00 0.77 1.99 2.58

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-33

 

 

     

Raw Assay

Capped Raw Assay

C_ESTIM

 C_Hole

# Samples

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

1151 2 3355 0.00 40.00 0.78 2.99 3.85 0.00 19.00 0.75 2.74 3.68
1300 1 1333 0.00 34.30 1.31 3.46 2.64 0.00 10.00 1.10 2.43 2.21
1300 2 984 0.00 22.54 0.51 1.99 3.87 0.00 7.00 0.41 1.29 3.15
1351 2 555 0.00 26.20 0.45 1.50 3.35 0.00 2.00 0.29 0.54 1.86
1402 1 138 0.03 12.80 1.76 2.19 1.24 0.03 8.00 1.71 1.98 1.16
1402 2 3483 0.00 31.16 0.91 2.08 2.30 0.00 12.00 0.88 1.87 2.13
1404 2 368 0.00 27.48 3.00 3.32 1.11 0.00 12.00 2.94 3.09 1.05
1408 1 4 0.06 15.40 5.19 6.22 1.20 0.06 15.40 5.19 6.22 1.20
1408 2 564 0.00 19.10 1.48 2.35 1.58 0.00 15.00 1.47 2.29 1.55
1450 1 153 0.00 24.97 1.98 2.65 1.34 0.00 9.50 1.91 2.34 1.23
1450 2 252 0.00 16.40 2.21 2.95 1.33 0.00 12.00 2.17 2.80 1.29
1458 1 281 0.00 23.37 1.75 2.80 1.60 0.00 12.00 1.69 2.43 1.44
1458 2 695 0.00 29.55 1.22 2.73 2.24 0.00 14.40 1.20 2.62 2.19
1504 1 139 0.00 8.60 0.15 0.87 5.96 0.00 0.20 0.03 0.04 1.49
1504 2 568 0.00 11.15 0.02 0.24 9.84 0.00 0.10 0.02 0.01 0.88
1555 1 1572 0.00 33.64 1.83 3.98 2.18 0.00 15.00 1.69 3.33 1.97
1555 2 2014 0.00 38.56 1.25 3.50 2.80 0.00 15.00 1.14 2.84 2.50
1607 1 306 0.00 22.89 0.96 1.83 1.91 0.00 15.00 0.95 1.74 1.83
1607 2 1002 0.00 31.86 1.57 3.16 2.01 0.00 15.00 1.50 2.73 1.83
1611 1 1 0.61 0.61 0.61 - - 0.61 0.61 0.61 - -
1611 2 89 0.00 20.44 1.06 2.17 2.06 0.00 11.50 1.03 1.99 1.93
1614 1 13 0.03 9.28 1.66 2.55 1.54 0.03 9.28 1.66 2.55 1.54
1614 2 118 0.00 29.73 2.56 4.38 1.71 0.00 20.00 2.50 4.07 1.63
1650 1 2089 0.00 62.83 0.47 2.20 4.68 0.00 4.00 0.32 0.83 2.61
1650 2 1281 0.00 15.99 0.05 0.37 6.74 0.00 0.30 0.03 0.05 1.90
1712 1 81 0.02 8.67 0.68 1.31 1.93 0.02 8.67 0.68 1.31 1.93
1712 2 408 0.00 35.34 2.59 5.24 2.02 0.00 24.00 2.49 4.71 1.89
1716 1 374 0.01 29.12 1.95 3.90 2.00 0.01 18.00 1.89 3.56 1.89
1716 2 485 0.00 27.31 1.74 3.49 2.01 0.00 25.00 1.74 3.47 2.00
1718 1 85 0.02 7.27 1.40 1.98 1.42 0.02 7.27 1.40 1.98 1.42
1718 2 73 0.00 16.77 0.79 2.22 2.81 0.00 3.00 0.47 0.75 1.61
1750 1 479 0.00 22.91 1.84 2.92 1.59 0.00 12.00 1.78 2.66 1.49
1750 2 407 0.00 40.61 2.46 4.51 1.83 0.00 15.00 2.32 3.87 1.66
1850 1 312 0.01 27.23 1.76 3.32 1.89 0.01 10.00 1.58 2.51 1.59
1850 2 800 0.00 31.49 1.06 2.93 2.77 0.00 8.00 0.84 1.61 1.92
1855 1 377 0.00 45.00 3.91 6.37 1.63 0.00 22.00 3.78 5.92 1.57
1855 2 1032 0.00 30.47 2.46 4.02 1.64 0.00 22.00 2.43 3.88 1.60
1900 1 1437 0.00 21.76 1.87 2.41 1.29 0.00 14.00 1.86 2.33 1.26

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-34

 

 

     

Raw Assay

Capped Raw Assay

C_ESTIM

 C_Hole

# Samples

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

1900 2 886 0.00 16.09 1.35 2.43 1.81 0.00 12.00 1.33 2.33 1.76
1960 1 520 0.00 17.52 0.62 1.26 2.03 0.00 5.30 0.58 0.92 1.59
1960 2 363 0.00 7.27 0.51 0.79 1.57 0.00 4.00 0.50 0.74 1.50
1965 1 216 0.01 12.81 1.62 2.10 1.29 0.01 7.00 1.56 1.85 1.19
1965 2 288 0.00 25.36 0.78 1.79 2.29 0.00 5.00 0.67 1.13 1.67
2000 1 25 0.01 1.56 0.42 0.37 0.90 0.01 1.56 0.42 0.37 0.90
2000 2 931 0.00 33.52 0.62 1.56 2.51 0.00 4.50 0.53 0.83 1.56
2051 2 388 0.00 16.27 0.90 1.70 1.89 0.00 8.40 0.86 1.43 1.66
2060 2 606 0.00 15.94 0.24 0.85 3.48 0.00 1.50 0.18 0.35 1.98
2067 2 22 0.00 0.15 0.02 0.04 1.66 0.00 0.15 0.02 0.04 1.66
2073 2 12 0.01 0.16 0.03 0.03 1.26 0.01 0.16 0.03 0.03 1.26
2079 2 19 0.00 0.78 0.14 0.20 1.43 0.00 0.78 0.14 0.20 1.43
2080 2 22 0.00 2.60 0.28 0.56 2.00 0.00 2.60 0.28 0.56 2.00
2083 2 71 0.00 0.41 0.01 0.04 3.02 0.00 0.05 0.01 0.01 1.17
2104 2 226 0.00 24.20 1.10 2.94 2.67 0.00 3.50 0.66 0.94 1.43
2156 1 1 0.48 0.48 0.48 - - 0.48 0.48 0.48 - -
2156 2 103 0.01 5.31 0.95 1.01 1.07 0.01 3.80 0.92 0.93 1.01
2591 1 1134 0.00 36.40 0.62 1.93 3.13 0.00 8.00 0.55 1.24 2.26
2591 2 43 0.00 2.35 0.12 0.38 3.14 0.00 2.00 0.11 0.34 3.00
2592 1 1102 0.00 10.80 0.16 0.81 5.14 0.00 2.8 0.11 0.38 3.40
2592 2 630 0.00 4.92 0.04 0.22 5.21 0.00 0.5 0.03 0.06 1.85

 

Note: 

C_Hole: 1: Channels, 2: Drill holes

 

Table 11-11:              Estimation Domain Capped and Raw Assay Statistics for Silver (Ag g/t)

Nexa Resources S.A. – El Porvenir Mine

 

     

Raw Assay

Capped Raw Assay

C_ESTIM

 C_Hole

# Samples

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

1 1 2363 0.00 1427.65 232.24 237.63 1.02 0.00 1000.00 230.22 229.67 1.00
1 2 2312 0.00 3864.61 152.62 301.30 1.97 0.00 2000.00 150.91 287.90 1.91
21 1 179 2.02 232.34 13.22 24.97 1.89 2.02 60.00 11.17 13.08 1.17
21 2 799 0.00 1009.93 19.80 53.12 2.68 0.00 300.00 18.40 35.35 1.92
100 1 486 0.00 1467.77 128.77 225.57 1.75 0.00 1200.00 127.59 219.41 1.72
100 2 2181 0.00 9873.80 167.16 449.62 2.69 0.00 2000.00 153.97 242.53 1.58
154 1 1449 0.00 1445.07 73.87 119.45 1.62 0.00 490.00 70.64 100.59 1.42

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-35

 

 

     

Raw Assay

Capped Raw Assay

C_ESTIM

 C_Hole

# Samples

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

154 2 2547 0.00 1287.99 36.48 89.38 2.45 0.00 420.00 33.70 68.46 2.03
157 1 77 1.24 377.91 98.93 73.16 0.74 1.24 220.00 94.90 61.70 0.65
185 1 34 2.02 880.85 105.99 179.96 1.70 2.02 250.00 75.82 66.56 0.88
185 2 537 0.00 2506.50 113.78 199.09 1.75 0.00 1000.00 108.14 153.43 1.42
201 2 24 0.00 2117.84 214.82 458.18 2.13 0.00 1600.00 205.02 421.44 2.06
256 1 9 5.29 208.08 78.89 76.75 0.97 5.29 208.08 78.89 76.75 0.97
256 2 273 0.00 775.10 55.56 99.34 1.79 0.00 500.00 53.23 84.66 1.59
264 2 184 0.00 143.39 18.38 15.87 0.86 0.00 60.00 17.61 11.45 0.65
307 1 5597 0.00 2901.95 58.28 97.66 1.68 0.00 1200.00 57.88 89.03 1.54
307 2 4339 0.00 926.88 19.36 37.22 1.92 0.00 400.00 19.20 34.69 1.81
308 1 71 2.02 479.93 40.52 65.14 1.61 2.02 179.00 36.46 43.32 1.19
308 2 177 1.40 805.00 30.41 72.62 2.39 1.40 435.00 28.93 59.50 2.06
309 1 57 2.02 692.36 62.07 107.90 1.74 2.02 400.00 58.74 91.65 1.56
309 2 155 0.00 1256.89 146.68 229.63 1.57 0.00 800.00 141.30 209.76 1.48
310 1 118 0.00 1679.59 291.47 399.35 1.37 0.00 1679.59 291.47 399.35 1.37
310 2 105 0.00 1819.86 159.61 275.33 1.72 0.00 1070.00 155.17 254.45 1.64
350 1 59 0.00 360.80 95.64 100.77 1.05 0.00 300.00 94.39 97.86 1.04
350 2 197 0.00 200.00 29.28 41.11 1.40 0.00 120.00 26.71 32.63 1.22
450 1 873 1.24 362.36 14.94 33.58 2.25 1.24 88.00 12.60 17.65 1.40
450 2 865 0.00 658.46 15.51 42.93 2.77 0.00 140.00 13.11 21.48 1.64
451 1 10 2.02 65.32 12.72 17.92 1.41 2.02 65.32 12.72 17.92 1.41
451 2 149 0.00 135.92 8.95 12.97 1.45 0.00 135.92 8.95 12.97 1.45
456 1 45 2.02 52.88 9.15 11.23 1.23 2.02 47.40 9.08 10.96 1.21
456 2 195 0.00 1182.24 55.69 143.69 2.58 0.00 450.00 47.84 100.42 2.10
458 1 77 2.02 142.76 7.78 18.60 2.39 2.02 61.50 6.68 11.76 1.76
458 2 381 0.00 530.31 7.32 18.97 2.59 0.00 57.00 6.78 8.51 1.25
466 1 1220 0.00 855.03 21.07 44.04 2.09 0.00 160.00 19.00 27.35 1.44
466 2 2793 0.00 1035.75 19.92 40.41 2.03 0.00 580.00 19.83 38.81 1.96
600 1 2141 0.00 1801.51 77.78 119.84 1.54 0.00 1100.00 77.26 114.32 1.48
600 2 2744 0.00 3278.62 48.99 116.26 2.37 0.00 900.00 47.87 100.53 2.10
671 1 30 4.04 534.98 84.69 118.63 1.40 4.04 534.98 84.69 118.63 1.40
671 2 767 0.00 9117.05 75.14 207.70 2.76 0.00 1300.00 71.45 126.80 1.77
700 1 272 2.02 2229.19 108.40 213.60 1.97 2.02 1200.00 105.17 190.78 1.81

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-36

 

 

     

Raw Assay

Capped Raw Assay

C_ESTIM

 C_Hole

# Samples

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

700 2 241 0.00 4321.30 138.10 329.57 2.39 0.00 1790.00 129.47 249.74 1.93
701 1 590 0.93 3801.78 333.27 470.02 1.41 0.93 3000.00 331.54 458.86 1.38
701 2 1657 0.00 6760.00 153.15 307.22 2.01 0.00 2000.00 149.70 265.54 1.77
750 1 11 31.41 265.93 110.78 86.24 0.78 31.41 265.93 110.78 86.24 0.78
750 2 1266 0.00 1153.15 55.18 85.24 1.54 0.00 825.00 54.78 80.93 1.48
751 1 54 4.04 2071.18 192.89 395.80 2.05 4.04 1922.00 189.91 381.99 2.01
751 2 195 0.00 931.86 63.07 68.10 1.08 0.00 420.00 62.55 63.26 1.01
756 2 225 0.00 1630.76 92.76 125.16 1.35 0.00 400.00 87.85 90.52 1.03
850 1 12 6.53 186.00 62.59 45.76 0.73 6.53 186.00 62.59 45.76 0.73
850 2 243 0.00 1792.49 124.18 211.75 1.71 0.00 1400.00 123.84 209.39 1.69
865 2 141 0.00 1035.71 113.78 126.95 1.12 0.00 581.00 112.48 120.13 1.07
878 2 73 0.00 388.08 37.60 45.21 1.20 0.00 170.00 35.75 35.13 0.98
883 1 11 46.66 738.09 158.63 130.99 0.83 46.66 738.09 158.63 130.99 0.83
883 2 38 4.48 2002.75 167.37 272.51 1.63 4.48 700.00 148.27 171.18 1.15
901 1 134 2.02 584.12 90.95 81.17 0.89 2.02 250.00 86.78 64.74 0.75
901 2 550 0.00 1418.63 126.21 142.67 1.13 0.00 1000.00 125.70 139.22 1.11
908 2 245 0.00 2022.97 105.29 174.54 1.66 0.00 1400.00 104.31 165.71 1.59
1028 1 455 2.02 2055.94 105.74 168.75 1.60 2.02 1000.00 102.63 140.32 1.37
1028 2 2709 0.00 2933.68 95.03 153.25 1.61 0.00 2000.00 94.80 149.92 1.58
1034 1 30 2.02 746.48 63.52 100.39 1.58 2.02 244.00 56.77 69.92 1.23
1034 2 559 0.00 1187.53 81.03 121.80 1.50 0.00 700.00 80.03 115.33 1.44
1151 1 1042 0.31 836.68 49.60 100.75 2.03 0.31 510.00 47.90 90.63 1.89
1151 2 3355 0.00 2504.00 48.11 134.07 2.79 0.00 1000.00 46.88 121.99 2.60
1300 1 1333 0.00 1100.75 68.05 118.28 1.74 0.00 900.00 67.75 115.93 1.71
1300 2 984 0.00 728.75 31.49 66.63 2.12 0.00 400.00 30.79 61.82 2.01
1351 2 555 0.00 833.88 48.52 60.50 1.25 0.00 600.00 48.38 58.95 1.22
1402 1 138 3.11 503.88 123.54 91.26 0.74 3.11 400.00 122.05 85.86 0.70
1402 2 3483 0.00 1026.13 75.67 80.06 1.06 0.00 712.00 75.53 78.72 1.04
1404 2 368 0.00 1293.59 146.85 122.59 0.83 0.00 900.00 146.48 119.93 0.82
1408 1 4 4.35 1279.29 369.92 546.51 1.48 4.35 1279.29 369.92 546.51 1.48
1408 2 564 0.00 1469.02 89.84 120.88 1.35 0.00 1050.00 88.75 109.96 1.24
1450 1 153 0.00 714.76 63.21 86.76 1.37 0.00 500.00 62.69 83.76 1.34
1450 2 252 0.00 1206.21 99.77 133.49 1.34 0.00 890.00 98.90 127.14 1.29

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-37

 

 

     

Raw Assay

Capped Raw Assay

C_ESTIM

 C_Hole

# Samples

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

1458 1 281 0.00 1100.13 96.68 151.63 1.57 0.00 850.00 95.21 143.09 1.50
1458 2 695 0.00 1567.49 98.75 215.11 2.18 0.00 1400.00 98.51 213.60 2.17
1504 1 139 0.93 320.68 15.55 35.40 2.28 0.93 70.00 12.21 12.77 1.05
1504 2 568 0.00 1148.03 16.70 33.50 2.01 0.00 210.00 15.97 16.04 1.00
1555 1 1572 0.00 2282.68 108.29 221.15 2.04 0.00 1800.00 107.69 216.02 2.01
1555 2 2014 0.00 5366.44 88.19 196.88 2.23 0.00 1600.00 87.49 185.20 2.12
1607 1 306 0.00 895.16 71.57 129.13 1.80 0.00 750.00 71.01 125.86 1.77
1607 2 1002 0.00 1669.01 139.00 239.04 1.72 0.00 1250.00 138.11 234.27 1.70
1611 1 1 284.29 284.29 284.29 - - 284.29 284.29 284.29 - -
1611 2 89 0.00 1482.39 248.75 293.32 1.18 0.00 1130.00 244.49 278.73 1.14
1614 1 13 4.04 470.60 87.16 124.75 1.43 4.04 470.60 87.16 124.75 1.43
1614 2 118 0.00 4381.24 219.35 345.19 1.57 0.00 1155.00 209.61 263.80 1.26
1650 1 2089 0.00 776.65 40.94 60.25 1.47 0.00 400.00 40.41 55.81 1.38
1650 2 1281 0.00 439.80 13.35 25.54 1.91 0.00 300.00 13.19 23.27 1.76
1712 1 81 2.02 654.42 78.38 120.30 1.53 2.02 600.00 78.04 118.73 1.52
1712 2 408 0.00 1363.92 113.58 172.20 1.52 0.00 900.00 110.35 152.73 1.38
1716 1 374 2.02 667.79 92.63 110.06 1.19 2.02 570.00 92.21 108.05 1.17
1716 2 485 0.00 1001.80 79.52 110.66 1.39 0.00 844.00 79.38 109.57 1.38
1718 1 85 0.31 265.62 65.68 55.96 0.85 0.31 214.00 64.71 52.93 0.82
1718 2 73 0.00 771.37 45.13 123.33 2.73 0.00 200.00 30.19 53.22 1.76
1750 1 479 2.02 1420.50 118.10 145.92 1.24 2.02 600.00 115.36 129.23 1.12
1750 2 407 0.00 2312.23 129.81 181.47 1.40 0.00 700.00 125.73 157.36 1.25
1850 1 312 2.02 1597.79 224.96 290.26 1.29 2.02 1500.00 224.38 287.59 1.28
1850 2 800 0.00 14727.19 184.32 488.68 2.65 0.00 2580.00 175.68 304.26 1.73
1855 1 377 0.00 1323.76 129.14 151.11 1.17 0.00 688.00 128.31 146.24 1.14
1855 2 1032 0.00 1806.99 120.63 181.64 1.51 0.00 1570.00 120.35 179.17 1.49
1900 1 1437 0.00 2237.58 119.12 141.16 1.19 0.00 1000.00 117.79 127.85 1.09
1900 2 886 0.00 6672.63 96.87 226.39 2.34 0.00 1500.00 92.62 131.54 1.42
1960 1 520 0.00 519.43 42.84 47.03 1.10 0.00 375.00 42.50 44.21 1.04
1960 2 363 0.00 1060.47 52.12 92.64 1.78 0.00 586.00 50.89 81.76 1.61
1965 1 216 1.24 777.90 103.59 114.68 1.11 1.24 438.00 100.43 100.60 1.00
1965 2 288 0.00 1098.57 50.49 104.30 2.07 0.00 400.00 46.19 72.26 1.56
2000 1 25 4.04 417.10 149.49 119.84 0.80 4.04 417.10 149.49 119.84 0.80

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-38

 

 

     

Raw Assay

Capped Raw Assay

C_ESTIM

 C_Hole

# Samples

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

2000 2 931 0.00 1030.15 39.77 84.11 2.11 0.00 320.00 36.00 55.62 1.55
2051 2 388 0.00 3634.28 95.09 228.50 2.40 0.00 2000.00 91.57 182.56 1.99
2060 2 606 0.00 565.15 22.78 48.28 2.12 0.00 400.00 22.49 45.52 2.02
2067 2 22 0.90 123.26 13.60 27.58 2.03 0.90 50.00 10.23 16.07 1.57
2073 2 12 1.00 67.20 8.11 15.59 1.92 1.00 67.20 8.11 15.59 1.92
2079 2 19 2.36 81.96 16.89 18.91 1.12 2.36 81.96 16.89 18.91 1.12
2080 2 22 0.00 284.60 28.82 39.09 1.36 0.00 284.60 28.82 39.09 1.36
2083 2 71 0.00 55.60 4.74 6.57 1.39 0.00 29.00 4.51 5.12 1.14
2104 2 226 2.00 1100.44 84.00 119.63 1.42 2.00 920.00 83.43 115.11 1.38
2156 1 1 18.04 18.04 18.04 - - 18.04 18.04 18.04 - -
2156 2 103 1.30 368.00 71.06 71.97 1.01 1.30 200.00 66.35 58.53 0.88
2591 1 1134 0.00 1100.13 72.30 82.17 1.14 0.00 600.00 71.51 74.69 1.04
2591 2 43 0.00 139.34 34.69 37.58 1.08 0.00 139.34 34.69 37.58 1.08
2592 1 1102 0.00 560.17 24.84 42.62 1.72 0.00 200.00 23.35 31.08 1.33
2592 2 630 0.00 235.14 15.38 21.15 1.38 0.00 100.00 14.82 17.40 1.17

 

Note:

C_Hole: 1: Channels, 2: Drill holes

 

Table 11-12:          Estimation Domain Capped and Raw Assay Statistics for Copper (Cu %)

Nexa Resources S.A. – El Porvenir Mine

 

     

Raw Assay

Capped Raw Assay

C_ESTIM

 C_Hole

# Samples

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

1 1 3365 0.00 11.58 0.28 0.48 1.69 0.00 2.70 0.27 0.33 1.23
1 2 3183 0.00 14.06 0.23 0.56 2.39 0.00 6.20 0.23 0.47 2.06
21 1 179 0.01 1.04 0.20 0.19 0.96 0.01 0.70 0.19 0.17 0.90
21 2 799 0.00 5.91 0.31 0.47 1.54 0.00 2.00 0.29 0.37 1.26
100 1 2262 0.00 30.69 0.23 1.13 4.96 0.00 1.30 0.12 0.28 2.23
100 2 4481 0.00 10.21 0.10 0.30 3.08 0.00 1.60 0.09 0.19 2.10
157 1 77 0.01 1.88 0.35 0.43 1.23 0.01 1.88 0.35 0.43 1.23
164 1 28 0.10 2.96 0.74 0.61 0.83 0.10 2.96 0.74 0.61 0.83
164 2 263 0.00 14.08 0.89 0.91 1.03 0.00 5.00 0.87 0.76 0.87
201 2 24 0.00 0.60 0.03 0.09 2.75 0.00 0.60 0.03 0.09 2.75
252 1 51 0.02 2.41 0.42 0.49 1.18 0.02 2.41 0.42 0.49 1.18
252 2 19 0.00 0.76 0.19 0.15 0.80 0.00 0.76 0.19 0.15 0.80

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-39

 

 

     

Raw Assay

Capped Raw Assay

C_ESTIM

 C_Hole

# Samples

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

259 1 2236 0.00 10.07 0.23 0.41 1.79 0.00 1.60 0.21 0.23 1.06
259 2 673 0.00 12.29 0.46 0.83 1.79 0.00 6.00 0.45 0.71 1.57
264 2 184 0.00 14.41 0.90 1.07 1.19 0.00 7.90 0.87 0.85 0.97
307 1 5597 0.00 12.10 0.41 0.43 1.05 0.00 4.30 0.41 0.41 1.02
307 2 4339 0.00 17.23 0.43 0.64 1.50 0.00 4.00 0.42 0.54 1.29
350 1 69 0.00 1.10 0.33 0.23 0.69 0.00 1.10 0.33 0.23 0.69
350 2 346 0.00 5.90 0.42 0.69 1.64 0.00 3.50 0.41 0.60 1.47
450 1 873 0.01 3.32 0.36 0.39 1.08 0.01 3.32 0.36 0.39 1.08
450 2 865 0.00 6.14 0.37 0.47 1.25 0.00 6.14 0.37 0.47 1.25
456 1 14 0.07 1.33 0.51 0.41 0.80 0.07 1.33 0.51 0.41 0.80
456 2 158 0.00 8.14 0.68 1.11 1.63 0.00 8.14 0.68 1.11 1.63
458 1 108 0.01 2.93 0.22 0.32 1.47 0.01 2.93 0.22 0.32 1.47
458 2 418 0.00 35.00 0.39 2.02 5.22 0.00 5.00 0.29 0.43 1.50
466 1 3333 0.00 6.30 0.15 0.29 1.92 0.00 2.70 0.15 0.26 1.74
466 2 5274 0.00 16.55 0.26 0.47 1.79 0.00 4.40 0.26 0.42 1.64
671 1 55 0.01 0.41 0.07 0.09 1.31 0.01 0.25 0.06 0.08 1.20
671 2 1698 0.00 4.09 0.02 0.06 3.52 0.00 0.18 0.02 0.03 1.74
700 1 272 0.01 0.12 0.02 0.02 1.07 0.01 0.10 0.02 0.02 1.06
700 2 241 0.00 4.17 0.03 0.20 6.19 0.00 0.12 0.02 0.03 1.30
701 1 590 0.00 1.61 0.08 0.15 1.91 0.00 1.61 0.08 0.15 1.91
701 2 1657 0.00 3.44 0.04 0.11 2.76 0.00 0.45 0.04 0.07 1.83
750 1 11 0.02 1.03 0.32 0.26 0.80 0.02 1.03 0.32 0.26 0.80
750 2 1266 0.00 3.38 0.14 0.35 2.42 0.00 1.00 0.12 0.23 1.93
751 1 54 0.01 0.32 0.04 0.06 1.56 0.01 0.26 0.04 0.06 1.49
751 2 195 0.00 1.15 0.05 0.14 2.58 0.00 0.25 0.04 0.06 1.68
756 2 225 0.00 3.58 0.22 0.41 1.83 0.00 1.80 0.21 0.35 1.66
852 2 86 0.00 4.94 0.55 0.64 1.17 0.00 4.94 0.55 0.64 1.17
860 1 12 0.00 0.11 0.02 0.03 1.14 0.00 0.11 0.02 0.03 1.14
860 2 199 0.00 5.04 0.11 0.26 2.32 0.00 1.00 0.10 0.16 1.53
864 2 44 0.00 2.78 0.38 0.47 1.24 0.00 2.78 0.38 0.47 1.24
865 2 128 0.00 0.92 0.12 0.15 1.21 0.00 0.92 0.12 0.15 1.21
883 1 11 0.03 0.41 0.07 0.05 0.82 0.03 0.41 0.07 0.05 0.82
883 2 38 0.01 0.65 0.18 0.17 0.93 0.01 0.65 0.18 0.17 0.93
901 1 111 0.01 2.11 0.23 0.35 1.51 0.01 1.90 0.23 0.34 1.48
901 2 530 0.00 6.38 0.22 0.39 1.81 0.00 2.50 0.21 0.27 1.31
902 1 23 0.01 0.46 0.08 0.10 1.30 0.01 0.46 0.08 0.10 1.30
902 2 265 0.00 0.84 0.08 0.11 1.35 0.00 0.84 0.08 0.11 1.35
1004 1 6 0.02 0.99 0.18 0.28 1.54 0.02 0.99 0.18 0.28 1.54

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-40

 

 

     

Raw Assay

Capped Raw Assay

C_ESTIM

 C_Hole

# Samples

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

1004 2 54 0.01 1.03 0.33 0.25 0.76 0.01 1.03 0.33 0.25 0.76
1008 1 34 0.00 0.13 0.02 0.03 1.39 0.00 0.13 0.02 0.03 1.39
1008 2 272 0.00 0.77 0.04 0.07 1.87 0.00 0.77 0.04 0.07 1.87
1010 1 48 0.00 0.94 0.10 0.19 1.97 0.00 0.94 0.10 0.19 1.97
1010 2 280 0.00 3.45 0.17 0.30 1.72 0.00 2.00 0.17 0.28 1.62
1023 1 177 0.01 0.30 0.03 0.04 1.32 0.01 0.30 0.03 0.04 1.32
1023 2 465 0.00 5.33 0.09 0.27 3.20 0.00 1.80 0.08 0.17 2.20
1028 1 272 0.01 0.79 0.05 0.08 1.53 0.01 0.79 0.05 0.08 1.53
1028 2 2190 0.00 4.64 0.09 0.14 1.51 0.00 0.82 0.09 0.11 1.25
1029 2 265 0.00 5.84 0.26 0.42 1.61 0.00 2.90 0.25 0.36 1.42
1034 1 45 0.00 0.50 0.05 0.07 1.55 0.00 0.50 0.05 0.07 1.55
1034 2 1103 0.00 1.38 0.07 0.11 1.51 0.00 0.63 0.07 0.10 1.39
1051 1 243 0.00 1.35 0.13 0.17 1.28 0.00 1.10 0.13 0.16 1.23
1051 2 1390 0.00 7.89 0.11 0.23 2.10 0.00 1.70 0.11 0.17 1.64
1300 1 1333 0.00 3.70 0.31 0.33 1.06 0.00 3.70 0.31 0.33 1.06
1300 2 984 0.00 3.52 0.20 0.34 1.65 0.00 1.90 0.20 0.31 1.54
1402 1 138 0.00 2.20 0.29 0.28 0.95 0.00 2.20 0.29 0.28 0.95
1402 2 3827 0.00 20.65 0.33 0.57 1.73 0.00 8.20 0.33 0.46 1.41
1404 2 579 0.00 5.67 0.75 0.63 0.85 0.00 3.40 0.74 0.58 0.79
1408 1 75 0.01 0.88 0.14 0.18 1.26 0.01 0.88 0.14 0.18 1.26
1408 2 741 0.00 2.67 0.22 0.29 1.32 0.00 1.60 0.21 0.25 1.17
1450 1 162 0.01 0.47 0.04 0.06 1.57 0.01 0.47 0.04 0.06 1.57
1450 2 127 0.00 0.38 0.04 0.07 1.69 0.00 0.38 0.04 0.07 1.69
1455 1 168 0.00 10.88 0.14 0.93 6.75 0.00 0.30 0.06 0.08 1.32
1455 2 329 0.00 0.34 0.03 0.06 1.92 0.00 0.34 0.03 0.06 1.92
1458 1 231 0.00 2.80 0.18 0.33 1.87 0.00 1.50 0.16 0.25 1.54
1458 2 471 0.00 3.14 0.21 0.38 1.79 0.00 3.14 0.21 0.38 1.79
1502 1 26 0.01 0.86 0.21 0.15 0.73 0.01 0.86 0.21 0.15 0.73
1502 2 280 0.01 10.50 1.07 1.08 1.00 0.01 7.50 1.06 0.99 0.93
1504 1 113 0.00 5.41 0.63 0.77 1.21 0.00 5.41 0.63 0.77 1.21
1504 2 288 0.00 13.46 0.72 0.87 1.21 0.00 4.90 0.70 0.77 1.09
1607 1 307 0.00 0.41 0.03 0.04 1.44 0.00 0.41 0.03 0.04 1.44
1607 2 1091 0.00 1.25 0.04 0.08 1.94 0.00 1.25 0.04 0.08 1.94
1614 1 13 0.01 0.13 0.04 0.04 1.03 0.01 0.13 0.04 0.04 1.03
1614 2 118 0.00 0.39 0.07 0.08 1.16 0.00 0.39 0.07 0.08 1.16
1650 1 2089 0.00 11.60 0.40 0.46 1.14 0.00 2.50 0.39 0.35 0.91
1650 2 1281 0.00 13.38 0.37 0.68 1.87 0.00 5.00 0.35 0.45 1.27
1702 1 189 0.01 4.91 0.34 0.51 1.50 0.01 4.91 0.34 0.51 1.50

  

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-41

 

 

     

Raw Assay

Capped Raw Assay

C_ESTIM

 C_Hole

# Samples

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

Min.(%)

Max.(%)

Mean(%)

Std. Dv

C.V.

1702 2 386 0.00 1.63 0.20 0.24 1.19 0.00 1.40 0.20 0.23 1.15
1712 1 30 0.01 0.75 0.08 0.16 2.02 0.01 0.75 0.08 0.16 2.02
1712 2 389 0.00 1.60 0.07 0.14 2.13 0.00 0.40 0.06 0.09 1.47
1716 1 194 0.00 0.84 0.11 0.15 1.27 0.00 0.84 0.11 0.15 1.27
1716 2 372 0.00 1.30 0.09 0.16 1.74 0.00 1.30 0.09 0.16 1.74
1718 1 85 0.00 0.40 0.08 0.09 1.21 0.00 0.40 0.08 0.09 1.21
1718 2 73 0.00 0.70 0.04 0.11 2.92 0.00 0.13 0.02 0.04 1.70
1750 1 479 0.00 1.75 0.17 0.20 1.22 0.00 1.20 0.16 0.19 1.18
1750 2 407 0.00 1.98 0.20 0.35 1.77 0.00 1.98 0.20 0.35 1.77
1850 1 312 0.00 1.02 0.05 0.10 1.98 0.00 1.02 0.05 0.10 1.98
1850 2 800 0.00 1.28 0.03 0.07 2.17 0.00 1.28 0.03 0.07 2.17
1855 1 362 0.00 2.60 0.29 0.32 1.11 0.00 1.50 0.28 0.28 1.00
1855 2 488 0.00 5.93 0.16 0.29 1.78 0.00 2.30 0.16 0.24 1.48
1900 1 1652 0.00 5.70 0.08 0.19 2.42 0.00 0.90 0.07 0.12 1.55
1900 2 1081 0.00 1.26 0.05 0.11 2.03 0.00 0.86 0.05 0.10 1.87
1960 1 305 0.00 1.02 0.15 0.14 0.93 0.00 1.02 0.15 0.14 0.93
1960 2 168 0.00 0.69 0.08 0.09 1.22 0.00 0.69 0.08 0.09 1.22
1965 1 216 0.00 0.68 0.05 0.08 1.57 0.00 0.68 0.05 0.08 1.57
1965 2 288 0.00 2.41 0.03 0.11 3.31 0.00 0.15 0.03 0.03 1.39
2051 2 388 0.00 3.52 0.06 0.20 3.06 0.00 1.70 0.06 0.13 2.22
2060 2 580 0.00 3.56 0.13 0.23 1.75 0.00 3.56 0.13 0.23 1.75
2065 2 71 0.00 1.22 0.28 0.27 0.96 0.00 1.22 0.28 0.27 0.96
2067 2 22 0.02 2.97 0.29 0.40 1.38 0.02 2.97 0.29 0.40 1.38
2069 2 26 0.00 1.02 0.33 0.25 0.76 0.00 1.02 0.33 0.25 0.76
2072 2 22 0.00 0.18 0.04 0.05 1.29 0.00 0.18 0.04 0.05 1.29
2073 2 12 0.02 0.29 0.11 0.08 0.72 0.02 0.29 0.11 0.08 0.72
2079 2 19 0.10 1.06 0.42 0.25 0.58 0.10 1.06 0.42 0.25 0.58
2104 2 226 0.01 2.99 0.29 0.42 1.47 0.01 1.90 0.28 0.36 1.32
2156 1 1 0.01 0.01 0.01 - - 0.01 0.01 0.01 - -
2156 2 103 0.00 0.15 0.02 0.03 1.24 0.00 0.15 0.02 0.03 1.24
11511 1 323 0.01 1.16 0.14 0.11 0.79 0.01 0.40 0.14 0.09 0.67
11511 2 2137 0.00 3.06 0.14 0.16 1.14 0.00 0.90 0.14 0.14 1.02
11512 1 719 0.00 6.41 0.27 0.43 1.57 0.00 1.20 0.25 0.20 0.82
11512 2 1218 0.00 14.81 0.31 0.54 1.73 0.00 2.00 0.30 0.25 0.85

 

Note:

C_Hole: 1: Channels, 2: Drill holes

 

SLR performed an independent capping analysis on some elements for some domains, as well as a visual validation of the block model in section and plan view. Log probability plots were inspected for some of these domains and SLR applied a capping grade using a combination of histograms, probability plots, and decile analyses. SLR found that most of the coefficients of variation (CV) after applying capping are low, with exception of a few domains with CV values more than 1.5. SLR considers that the capping levels selected are appropriate.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-42

 

 

SLR offers the following conclusions and recommendations:

 

In general, the capping levels are reasonable, and suitable for the estimation of Mineral Resources.

 

Silver and lead grades increased in comparison with previous estimates. SLR prepared independent silver capping analysis for some domains and these values were 3% to 5% less than Nexa silver capping values. Currently, there is not a well established reconciliation process to evaluate if the higher silver capping levels are reasonable. SLR recommends monitoring the silver and lead grades with grade control and head grade from the plant to compare with the model and to calibrate the silver capping values.

 

Investigate if capping levels should be applied based on high grade and low grade domains for lead, copper, and silver.

 

Report the metal loss as a result of capping high grades, and assess the amount of metal in the upper decile and percentiles of the distribution to gain a better understanding of the amount of risk associated with extreme values in each capping domain. For the major domain contributor to the Mineral Reserve and Mineral Resources (C_ESTAG 1151 Mineralization domain), there is still 58% of the total metal within the upper decile of the silver distribution.

 

Adjust capping values with production data when an accurate reconciliation process is established.

 

11.8 Compositing

 

Nexa composited the capped assays to 2.0 m with a 1.0 m tolerance, beginning at the collars. Small intervals were merged with the previous interval. Sample lengths range from 0.1 m to 3.0 m. Composites were generated inside the mineralization domain wireframes, flagged by mineralization domain. The majority of samples (89%) had a length from 0.9 m to 2.0 m. Unsampled core intervals were assigned half of the detection limit value for each of the elements. The composite length corresponds to half of the parent block size height for the deposit. Figure 11-12 illustrates a comparison of the mean relative error between length-weighted composites at different composite lengths versus assay means by mineralization domain. Based on this analysis, the two metre composites result in the best correlation between assay data and composites. Nexa generated statistics of the composites is presented in Table 11-13, Table 11-14, Table 11-15, and Table 11-16.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-43

 

 

 

 

Figure 11-12: Composite Length Comparison

 

Table 11-13: Estimation Domain Composite Statistics for Zinc (Zn %) 

Nexa Resources S.A. – El Porvenir Mine

 

C_ESTIM   C_Hole   #
Samples
  Min.
(%)
  Max.
(%)
  Mean
(%)
  Std. Dv
(%)
  C.V.
1   1   2865   0.00   49.48   10.48   8.58   0.82
1   2   822   0.00   37.17   3.54   5.66   1.60
21   1   127   0.03   20.00   4.47   5.00   1.12
21   2   410   0.00   32.29   4.58   5.63   1.23
100   1   346   0.02   31.26   3.97   5.28   1.33
100   2   980   0.00   33.99   4.65   5.98   1.29
154   1   769   0.00   31.00   6.04   6.61   1.09
154   2   870   0.00   35.13   6.13   6.17   1.01
157   1   59   0.04   23.00   10.60   7.13   0.67
201   2   8   0.00   5.97   2.00   2.10   1.05
250   1   155   0.08   32.00   8.01   7.25   0.90
250   2   25   0.00   19.78   8.35   6.40   0.77
256   1   6   1.53   13.83   7.28   4.33   0.59
256   2   118   0.00   16.42   2.48   3.11   1.26
259   1   2064   0.00   41.20   8.07   6.71   0.83
259   2   405   0.00   29.80   4.22   5.22   1.24
264   2   102   0.03   24.25   5.66   4.78   0.84
270   1   26   0.07   23.20   4.39   5.50   1.25

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-44

 

 

C_ESTIM   C_Hole   #
Samples
  Min.
(%)
  Max.
(%)
  Mean
(%)
  Std. Dv
(%)
  C.V.
270   2   95   0.00   26.58   5.19   5.56   1.07
302   1   16   0.03   5.01   0.56   1.23   2.19
302   2   105   0.00   1.50   0.38   0.48   1.25
306   1   44   0.12   5.92   2.02   1.81   0.90
306   2   219   0.00   12.29   2.02   2.81   1.39
307   1   5019   0.00   37.00   6.95   6.62   0.95
307   2   2117   0.00   27.00   2.19   3.50   1.60
350   1   54   0.00   19.64   6.30   5.45   0.86
350   2   196   0.00   29.04   4.46   4.89   1.10
453   1   24   0.02   24.87   5.44   6.43   1.18
453   2   77   0.00   32.42   3.31   6.03   1.82
458   1   88   0.01   9.50   2.49   2.66   1.07
458   2   219   0.00   11.97   3.47   2.64   0.76
466   1   864   0.00   36.00   4.77   5.62   1.18
466   2   1341   0.00   31.17   4.23   5.16   1.22
550   1   1   14.73   14.73   14.73   -   -
550   2   431   0.00   34.77   3.05   5.00   1.64
600   1   1940   0.00   24.00   1.94   2.62   1.35
600   2   931   0.00   27.95   2.44   3.63   1.49
652   1   6   0.07   0.72   0.43   0.25   0.57
652   2   330   0.00   2.00   0.23   0.39   1.70
671   1   17   0.04   5.02   1.25   1.35   1.09
671   2   250   0.00   7.61   0.66   0.93   1.42
674   1   10   0.02   3.45   0.51   1.06   2.10
674   2   107   0.00   5.61   0.59   0.92   1.56
677   2   251   0.00   4.54   0.45   0.66   1.47
700   1   202   0.04   42.44   6.76   9.07   1.34
700   2   119   0.00   28.12   3.44   5.09   1.48
701   1   460   0.01   38.24   4.06   5.52   1.36
701   2   405   0.00   24.65   2.07   3.31   1.59
750   1   7   0.04   3.69   0.57   1.24   2.17
750   2   755   0.00   16.13   1.57   2.03   1.30
751   1   8   0.01   1.33   0.50   0.39   0.77
751   2   76   0.00   4.27   1.39   1.09   0.78
756   2   115   0.00   7.70   1.14   1.66   1.46
800   1   37   0.02   3.33   0.50   0.67   1.33
800   2   30   0.00   8.00   1.34   2.26   1.68
850   2   61   0.00   27.64   4.96   5.29   1.07
860   1   12   0.26   13.83   3.15   3.82   1.21

  

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-45

 

 

C_ESTIM   C_Hole   #
Samples
  Min.
(%)
  Max.
(%)
  Mean
(%)
  Std. Dv
(%)
  C.V.
860   2   86   0.00   12.74   2.20   2.34   1.06
865   2   62   0.00   24.55   5.51   5.80   1.05
872   2   67   0.00   14.50   2.02   2.34   1.16
883   1   8   3.09   7.89   5.53   1.72   0.31
883   2   21   0.33   15.70   5.68   3.82   0.67
901   1   109   0.01   12.50   2.50   2.38   0.95
901   2   312   0.00   26.50   3.77   3.69   0.98
908   2   110   0.00   17.42   2.28   2.40   1.06
950   1   20   0.30   17.00   5.81   4.97   0.85
950   2   153   0.00   23.04   3.87   4.93   1.27
1008   1   9   0.04   26.07   4.36   7.91   1.81
1008   2   104   0.00   17.97   1.54   2.60   1.69
1016   1   50   0.11   4.34   1.00   0.95   0.95
1016   2   98   0.00   24.50   3.50   4.44   1.27
1019   2   121   0.00   15.93   2.37   2.83   1.19
1026   1   161   0.03   10.00   1.31   1.47   1.12
1026   2   296   0.00   16.30   1.61   2.33   1.45
1028   1   137   0.03   12.72   2.23   2.46   1.10
1028   2   1160   0.00   17.82   2.04   1.99   0.97
1029   1   18   0.70   10.80   2.64   2.12   0.80
1029   2   189   0.00   17.09   2.93   2.64   0.90
1034   1   11   0.03   1.24   0.42   0.46   1.10
1034   2   156   0.00   24.78   1.82   2.83   1.56
1054   1   1   4.12   4.12   4.12   -   -
1054   2   8   0.34   26.52   13.78   8.21   0.60
1151   1   883   0.01   22.00   5.20   4.91   0.94
1151   2   1796   0.00   32.39   5.03   5.00   0.99
1208   2   63   0.00   37.46   6.56   6.73   1.03
1300   1   1211   0.00   36.50   7.78   6.51   0.84
1300   2   409   0.00   31.83   3.97   5.40   1.36
1350   1   47   1.55   24.50   13.22   5.53   0.42
1350   2   980   0.00   24.27   4.82   4.18   0.87
1402   1   72   0.29   13.00   4.54   2.35   0.52
1402   2   1501   0.00   18.49   3.57   3.26   0.91
1408   2   267   0.00   16.00   3.31   2.90   0.88
1410   2   262   0.00   14.09   2.08   2.52   1.21
1450   1   79   0.10   7.74   1.50   1.73   1.16
1450   2   136   0.00   12.64   2.33   2.23   0.96
1452   1   68   0.02   11.26   1.73   2.81   1.62

  

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-46

 

 

C_ESTIM   C_Hole   #
Samples
  Min.
(%)
  Max.
(%)
  Mean
(%)
  Std. Dv
(%)
  C.V.
1452   2   92   0.00   15.65   3.71   3.81   1.03
1458   1   257   0.00   30.00   3.95   5.44   1.38
1458   2   129   0.00   15.75   2.67   3.50   1.31
1504   1   81   0.02   15.50   1.65   2.44   1.47
1504   2   266   0.01   23.00   2.63   4.74   1.80
1555   1   707   0.01   24.80   2.94   4.04   1.37
1555   2   951   0.00   28.73   3.11   4.02   1.29
1558   1   112   0.01   15.02   1.46   2.33   1.60
1558   2   433   0.00   26.44   1.71   2.90   1.70
1607   1   225   0.00   10.36   0.85   1.45   1.71
1607   2   364   0.00   19.94   1.56   2.46   1.58
1609   1   23   0.03   1.73   0.58   0.55   0.96
1609   2   134   0.00   7.60   0.93   1.45   1.56
1614   1   11   0.04   5.25   1.90   1.69   0.89
1614   2   68   0.00   23.00   3.18   4.49   1.41
1650   1   1861   0.00   36.00   7.35   6.31   0.86
1650   2   762   0.00   28.14   3.27   4.31   1.32
1702   1   112   0.04   16.39   2.82   3.22   1.14
1702   2   128   0.00   29.32   3.12   4.20   1.35
1712   1   31   0.02   15.50   2.48   3.74   1.51
1712   2   101   0.00   18.32   2.52   3.74   1.49
1714   1   33   0.34   12.04   3.39   2.78   0.82
1714   2   120   0.00   24.60   5.49   5.49   1.00
1718   1   60   0.03   13.19   3.32   3.11   0.94
1718   2   28   0.00   13.00   1.41   3.09   2.20
1754   1   36   0.33   10.40   3.20   2.55   0.80
1754   2   486   0.00   25.88   2.56   2.87   1.12
1755   2   4   0.48   15.79   5.92   6.23   1.05
1850   1   266   0.01   17.00   2.27   3.47   1.53
1850   2   349   0.00   17.50   1.18   1.92   1.62
1855   1   322   0.00   30.00   10.31   7.65   0.74
1855   2   53   0.00   22.00   4.26   6.28   1.47
1900   1   1029   0.00   24.74   4.49   4.72   1.05
1900   2   478   0.00   17.26   2.48   2.89   1.16
1950   1   192   0.01   12.00   1.97   2.25   1.14
1950   2   141   0.00   9.23   1.34   1.79   1.34
1959   1   399   0.00   9.50   1.60   1.65   1.03
1959   2   212   0.00   16.20   1.48   2.12   1.43
1965   1   185   0.02   12.00   1.80   2.21   1.23

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-47

 

 

C_ESTIM   C_Hole   #
Samples
  Min.
(%)
  Max.
(%)
  Mean
(%)
  Std. Dv
(%)
  C.V.
1965   2   187   0.00   11.25   1.02   1.66   1.63
2000   1   17   0.09   5.78   1.76   1.77   1.00
2000   2   193   0.02   10.90   1.41   1.31   0.93
2051   2   254   0.04   16.50   1.52   1.80   1.19
2060   2   284   0.00   15.41   1.84   2.43   1.33
2065   2   41   0.00   20.00   4.32   4.02   0.93
2067   2   18   0.05   14.00   2.44   3.48   1.42
2072   2   13   0.00   6.36   1.66   1.97   1.19
2073   2   6   0.16   3.49   2.06   1.19   0.58
2079   2   12   0.05   7.08   3.89   1.84   0.47
2100   1   61   0.06   8.54   2.00   2.04   1.02
2100   2   171   0.00   12.62   2.07   2.13   1.03
2104   2   135   0.03   21.22   2.60   3.26   1.25
2150   2   448   0.00   7.79   0.82   1.18   1.43
2156   1   1   0.72   0.72   0.72   -   -
2156   2   68   0.01   3.15   0.77   0.85   1.10
4501   1   148   0.01   9.00   2.62   2.63   1.00
4501   2   188   0.00   15.22   3.62   3.17   0.88
4502   1   527   0.01   27.00   6.38   5.19   0.81
4502   2   300   0.02   21.80   5.76   4.01   0.70
17501   1   148   0.01   20.00   8.18   6.81   0.83
17501   2   34   0.00   15.00   5.93   4.60   0.78
17502   1   220   0.02   15.00   2.97   3.56   1.20
17502   2   146   0.00   17.33   3.71   4.07   1.10

 

  Note:  
 
  C_Hole: 1: Channels, 2: Drill holes  

 

Table 11-14: Estimation Domain Composite Statistics for Lead (Pb%)

Nexa Resources S.A. – El Porvenir Mine

 

C_ESTIM   Field   #
Samples
  Min.
(%)
  Max.
(%)
  Mean
(%)
  Std. Dv
(%)
  C.V.
1   1   2104   0.00   30.00   6.54   6.84   1.05
1   2   948   0.00   25.67   2.59   4.34   1.68
21   1   127   0.01   0.20   0.04   0.04   1.06
21   2   410   0.00   3.32   0.10   0.31   3.16
100   1   360   0.02   20.00   1.97   3.27   1.66
100   2   959   0.00   29.77   2.70   3.71   1.37
154   1   1022   0.00   45.78   1.61   3.61   2.24
154   2   1183   0.00   6.50   0.33   0.97   2.97

  

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-48

 

(GRAPHIC)

 

C_ESTIM   Field   #
Samples
  Min.
(%)
  Max.
(%)
  Mean
(%)
  Std. Dv
(%)
  C.V.
157   1   59   0.03   15.50   1.78   3.11   1.75
185   1   27   0.04   15.80   1.89   2.77   1.46
185   2   293   0.00   14.30   1.98   2.34   1.18
201   2   8   0.00   11.20   3.99   3.85   0.96
256   1   6   0.01   0.64   0.20   0.21   1.05
256   2   118   0.00   9.66   0.86   1.60   1.87
264   2   102   0.00   0.05   0.01   0.01   0.60
307   1   5035   0.00   9.00   0.75   1.86   2.47
307   2   2222   0.00   2.00   0.09   0.27   2.93
308   1   58   0.02   5.03   0.41   0.76   1.88
308   2   119   0.00   0.90   0.09   0.19   2.12
309   1   47   0.07   11.17   1.39   2.21   1.58
309   2   72   0.00   13.16   2.44   3.17   1.30
310   1   91   0.05   22.00   5.74   6.21   1.08
310   2   46   0.00   20.54   3.04   4.60   1.51
350   1   44   0.00   10.00   1.76   2.71   1.54
350   2   117   0.00   2.00   0.21   0.46   2.21
450   1   675   0.01   1.50   0.07   0.23   3.11
450   2   488   0.00   2.50   0.08   0.28   3.39
451   1   10   0.01   0.17   0.03   0.05   1.51
451   2   79   0.00   0.24   0.03   0.05   1.63
456   1   38   0.01   1.12   0.11   0.26   2.29
456   2   97   0.00   5.50   0.60   1.30   2.17
458   1   74   0.01   0.10   0.02   0.02   1.06
458   2   199   0.00   0.28   0.02   0.03   1.33
466   1   949   0.00   2.00   0.12   0.33   2.69
466   2   1415   0.00   1.30   0.08   0.19   2.45
600   1   1856   0.00   12.00   1.27   1.70   1.34
600   2   1288   0.00   6.00   0.48   1.00   2.07
671   1   28   0.02   8.56   1.37   1.94   1.41
671   2   501   0.00   9.50   1.12   1.35   1.20
700   1   202   0.02   20.00   3.47   4.78   1.37
700   2   119   0.00   23.87   2.75   4.72   1.72
701   1   460   0.02   28.00   5.11   5.02   0.98
701   2   853   0.00   22.00   2.05   3.19   1.56
750   1   7   0.02   0.08   0.05   0.02   0.43
750   2   755   0.00   8.90   0.87   1.34   1.53
751   1   45   0.01   29.86   3.51   6.11   1.74
751   2   106   0.00   9.24   1.29   1.40   1.08

  

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-49

 

(GRAPHIC)

 

C_ESTIM   Field   #
Samples
  Min.
(%)
  Max.
(%)
  Mean
(%)
  Std. Dv
(%)
  C.V.
756   2   115   0.00   7.34   0.90   1.40   1.55
850   1   12   0.14   5.12   1.57   1.27   0.81
850   2   147   0.00   19.00   1.79   2.71   1.52
865   2   85   0.00   8.60   1.04   1.81   1.74
878   2   44   0.00   3.22   0.35   0.64   1.84
883   1   8   1.89   5.57   4.20   1.12   0.27
883   2   21   0.01   11.98   3.42   3.62   1.06
901   1   109   0.08   8.00   1.55   1.71   1.10
901   2   312   0.00   15.92   2.27   2.61   1.15
908   2   110   0.00   11.95   2.17   2.20   1.01
1028   1   348   0.04   11.50   1.73   1.95   1.13
1028   2   1554   0.00   23.03   1.91   2.18   1.14
1034   1   24   0.05   10.00   1.37   1.96   1.43
1034   2   335   0.00   14.00   1.76   2.10   1.19
1151   1   883   0.00   11.00   0.77   1.85   2.40
1151   2   1796   0.00   19.00   0.75   2.29   3.07
1300   1   1211   0.00   10.00   1.10   2.39   2.17
1300   2   409   0.00   7.00   0.41   1.10   2.68
1351   2   368   0.00   2.00   0.29   0.51   1.74
1402   1   119   0.03   8.00   1.71   1.95   1.14
1402   2   2123   0.00   11.94   0.88   1.59   1.81
1404   2   252   0.00   12.00   2.94   2.63   0.89
1408   1   3   0.70   9.92   5.19   4.06   0.78
1408   2   319   0.00   10.17   1.47   1.91   1.30
1450   1   100   0.01   9.50   1.91   1.95   1.02
1450   2   156   0.00   12.00   2.17   2.26   1.04
1458   1   210   0.00   12.00   1.69   2.19   1.29
1458   2   302   0.00   9.94   1.20   1.96   1.63
1504   1   107   0.00   0.20   0.03   0.04   1.41
1504   2   361   0.00   0.08   0.02   0.01   0.72
1555   1   1314   0.00   15.00   1.69   2.96   1.75
1555   2   974   0.00   15.00   1.14   2.29   2.02
1607   1   247   0.00   10.86   0.95   1.40   1.47
1607   2   454   0.00   15.00   1.50   2.16   1.44
1611   1   1   0.61   0.61   0.61   -   -
1611   2   44   0.00   5.80   1.03   1.42   1.38
1614   1   11   0.03   9.28   1.66   2.46   1.48
1614   2   68   0.00   20.00   2.50   3.48   1.39
1650   1   1861   0.00   4.00   0.32   0.81   2.57

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-50

 

(GRAPHIC)

 

C_ESTIM   Field   #
Samples
  Min.
(%)
  Max.
(%)
  Mean
(%)
  Std. Dv
(%)
  C.V.
1650   2   762   0.00   0.30   0.03   0.05   1.66
1712   1   64   0.02   6.33   0.68   1.14   1.68
1712   2   221   0.00   24.00   2.49   3.87   1.55
1716   1   267   0.02   18.00   1.89   3.16   1.67
1716   2   274   0.00   21.41   1.74   2.81   1.62
1718   1   60   0.02   7.27   1.40   1.85   1.33
1718   2   28   0.00   3.00   0.47   0.70   1.48
1750   1   368   0.00   12.00   1.78   2.38   1.33
1750   2   180   0.00   13.96   2.32   3.13   1.35
1850   1   266   0.01   10.00   1.58   2.33   1.48
1850   2   349   0.00   8.00   0.84   1.25   1.49
1855   1   365   0.00   22.00   3.78   5.84   1.55
1855   2   517   0.00   22.00   2.43   2.93   1.21
1900   1   1167   0.00   14.00   1.86   2.21   1.19
1900   2   608   0.00   12.00   1.33   2.10   1.58
1960   1   453   0.00   5.30   0.58   0.87   1.50
1960   2   223   0.00   3.67   0.50   0.65   1.31
1965   1   185   0.01   7.00   1.56   1.78   1.14
1965   2   187   0.00   5.00   0.67   1.02   1.51
2000   1   22   0.03   1.56   0.42   0.36   0.87
2000   2   630   0.00   4.50   0.53   0.71   1.33
2051   2   254   0.03   8.40   0.86   1.15   1.34
2060   2   347   0.00   1.50   0.18   0.31   1.72
2067   2   18   0.00   0.13   0.02   0.04   1.48
2073   2   6   0.01   0.10   0.03   0.03   1.04
2079   2   12   0.01   0.55   0.14   0.17   1.18
2080   2   13   0.00   1.55   0.28   0.43   1.56
2083   2   41   0.00   0.05   0.01   0.01   1.08
2104   2   135   0.00   3.50   0.66   0.78   1.18
2156   1   1   0.48   0.48   0.48   -   -
2156   2   68   0.01   3.80   0.92   0.81   0.88
2591   1   1039   0.00   8.00   0.55   1.21   2.22
2591   2   21   0.00   1.88   0.11   0.33   2.93
2592   1   1025   0.00   2.80   0.11   0.38   3.38
2592   2   384   0.00   0.48   0.03   0.05   1.66

 

Note. C_Hole: 1: Channels, 2: Drill holes

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-51

 

(GRAPHIC)

 

Table 11-15: Estimation Domain Composite Statistics for Silver (Ag g/t) 

Nexa Resources S.A. – El Porvenir Mine

 

C_ESTIM   C_Hole   # Samples   Min.
(g/t)
  Max.
(g/t)
  Mean
(g/t)
  Std. Dv
(g/t)
  C.V.
1   1   2104   0.00   1000.00   230.22   223.70   0.97
1   2   948   0.00   2000.00   150.89   240.77   1.60
21   1   127   2.02   60.00   11.17   11.94   1.07
21   2   410   0.00   258.95   18.40   28.85   1.57
100   1   360   2.02   1200.00   127.59   190.70   1.49
100   2   959   0.00   2000.00   153.96   179.51   1.17
154   1   1022   0.00   490.00   70.64   89.57   1.27
154   2   1183   0.00   420.00   33.70   59.82   1.78
157   1   59   5.91   220.00   94.90   58.14   0.61
185   1   27   2.02   250.00   75.82   54.24   0.72
185   2   293   0.00   714.38   108.13   113.72   1.05
201   2   8   0.00   634.72   205.02   220.17   1.07
256   1   6   5.44   202.48   78.89   66.25   0.84
256   2   118   0.00   355.96   53.23   62.68   1.18
264   2   102   0.25   58.54   17.61   9.09   0.52
307   1   5035   0.00   1200.00   57.88   87.61   1.51
307   2   2222   0.00   400.00   19.20   29.14   1.52
308   1   58   2.02   150.23   36.46   32.24   0.88
308   2   119   1.64   411.28   28.93   50.58   1.75
309   1   47   2.02   300.82   58.74   74.20   1.26
309   2   72   0.00   800.00   141.22   156.26   1.11
310   1   91   1.87   1601.67   291.47   348.88   1.20
310   2   46   0.00   854.15   155.07   196.78   1.27
350   1   44   0.00   289.26   94.39   96.31   1.02
350   2   117   0.00   120.00   26.71   29.62   1.11
450   1   675   1.37   88.00   12.60   16.39   1.30
450   2   488   0.00   137.47   13.11   18.52   1.41
451   1   10   2.02   65.32   12.72   17.92   1.41
451   2   79   0.00   43.08   8.95   8.76   0.98
456   1   38   2.02   47.40   9.08   10.67   1.18
456   2   97   0.00   415.63   47.82   85.98   1.80
458   1   74   2.02   61.50   6.68   11.76   1.76
458   2   199   0.00   34.24   6.78   6.81   1.00
466   1   949   0.00   160.00   19.00   25.88   1.36
466   2   1415   0.00   300.45   19.83   29.01   1.46
600   1   1856   0.00   1100.00   77.26   110.94   1.44
600   2   1288   0.00   900.00   47.88   83.86   1.75

  

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-52

 

(GRAPHIC)

 

C_ESTIM   C_Hole   # Samples   Min.
(g/t)
  Max.
(g/t)
  Mean
(g/t)
  Std. Dv
(g/t)
  C.V.
671   1   28   4.04   534.98   84.69   118.40   1.40
671   2   501   0.00   969.50   71.45   94.62   1.32
700   1   202   2.02   1200.00   105.17   163.95   1.56
700   2   119   0.00   1120.04   129.47   208.17   1.61
701   1   460   2.02   3000.00   331.54   414.20   1.25
701   2   853   0.00   1925.58   149.70   221.07   1.48
750   1   7   32.75   265.93   110.78   75.09   0.68
750   2   755   0.00   755.46   54.78   71.13   1.30
751   1   45   4.04   1559.25   189.91   321.41   1.69
751   2   106   0.00   323.01   62.54   53.41   0.85
756   2   115   0.00   329.67   87.81   78.05   0.89
850   1   12   6.53   186.00   62.59   45.76   0.73
850   2   147   0.00   1400.00   123.84   171.88   1.39
865   2   85   0.00   500.78   112.48   105.11   0.93
878   2   44   0.00   126.06   35.75   26.48   0.74
883   1   8   96.73   230.48   158.63   49.25   0.31
883   2   21   5.18   383.18   148.27   126.56   0.85
901   1   109   2.02   250.00   86.78   61.53   0.71
901   2   312   0.00   859.83   125.71   113.23   0.90
908   2   110   0.00   662.63   104.31   108.88   1.04
1028   1   348   2.02   850.68   102.63   117.26   1.14
1028   2   1554   0.00   1404.94   94.79   116.40   1.23
1034   1   24   2.02   244.00   56.77   60.41   1.06
1034   2   335   0.00   700.00   80.03   91.30   1.14
1151   1   883   0.31   510.00   47.90   84.26   1.76
1151   2   1796   0.00   1000.00   46.88   103.40   2.21
1300   1   1211   0.00   900.00   67.75   113.27   1.67
1300   2   409   0.00   400.00   30.78   53.34   1.73
1351   2   368   0.00   534.52   48.38   50.85   1.05
1402   1   119   3.11   400.00   122.05   83.23   0.68
1402   2   2123   0.00   668.72   75.53   67.65   0.90
1404   2   252   0.00   900.00   146.48   98.50   0.67
1408   1   3   17.42   823.95   369.92   380.80   1.03
1408   2   319   0.00   498.27   88.75   82.38   0.93
1450   1   100   1.98   500.00   62.69   71.44   1.14
1450   2   156   0.00   569.89   98.90   91.62   0.93
1458   1   210   0.00   817.98   95.21   128.33   1.35
1458   2   302   0.00   1229.95   98.50   152.15   1.54
1504   1   107   0.93   70.00   12.21   11.99   0.98

  

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-53

 

(GRAPHIC)

 

C_ESTIM   C_Hole   # Samples   Min.
(g/t)
  Max.
(g/t)
  Mean
(g/t)
  Std. Dv
(g/t)
  C.V.
1504   2   361   0.00   114.31   15.97   12.43   0.78
1555   1   1314   0.00   1800.00   107.69   185.06   1.72
1555   2   974   0.00   1528.42   87.48   152.08   1.74
1607   1   247   0.00   750.00   71.01   111.94   1.58
1607   2   454   0.00   1192.70   138.10   191.96   1.39
1611   1   1   284.29   284.29   284.29   -   -
1611   2   44   0.00   1130.00   244.49   236.74   0.97
1614   1   11   4.04   470.60   87.16   121.19   1.39
1614   2   68   0.00   1155.00   209.61   232.32   1.11
1650   1   1861   0.00   400.00   40.41   54.94   1.36
1650   2   762   0.00   300.00   13.19   19.28   1.46
1712   1   64   2.02   599.68   78.04   108.51   1.39
1712   2   221   0.00   900.00   110.35   125.61   1.14
1716   1   267   2.07   492.91   92.21   94.40   1.02
1716   2   274   0.00   579.06   79.38   82.96   1.05
1718   1   60   0.31   209.95   64.71   46.65   0.72
1718   2   28   0.00   200.00   30.19   50.67   1.68
1750   1   368   2.02   600.00   115.36   117.93   1.02
1750   2   180   0.00   698.47   125.70   129.61   1.03
1850   1   266   2.02   1500.00   224.38   267.55   1.19
1850   2   349   0.00   1529.36   175.69   237.47   1.35
1855   1   365   0.00   681.17   128.31   143.14   1.12
1855   2   517   0.00   1285.36   120.33   133.11   1.11
1900   1   1167   0.00   1000.00   117.79   119.30   1.01
1900   2   608   0.00   788.24   92.62   108.72   1.17
1960   1   453   0.00   375.00   42.50   40.42   0.95
1960   2   223   0.00   586.00   50.89   74.28   1.46
1965   1   185   1.24   438.00   100.43   95.57   0.95
1965   2   187   0.00   307.61   46.19   59.22   1.28
2000   1   22   7.46   417.10   149.49   116.78   0.78
2000   2   630   0.00   320.00   36.00   48.47   1.35
2051   2   254   1.00   1344.90   91.57   144.04   1.57
2060   2   347   0.00   368.74   22.49   40.35   1.79
2067   2   18   0.90   50.00   10.23   14.94   1.46
2073   2   6   1.00   44.05   8.11   13.61   1.68
2079   2   12   2.86   49.16   16.89   14.55   0.86
2080   2   13   0.00   90.46   28.82   24.76   0.86
2083   2   41   0.00   29.00   4.51   4.53   1.01
2104   2   135   2.90   557.75   83.43   85.51   1.02

  

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-54

 

(GRAPHIC)

 

C_ESTIM   C_Hole   # Samples   Min.
(g/t)
  Max.
(g/t)
  Mean
(g/t)
  Std. Dv
(g/t)
  C.V.
2156   1   1   18.04   18.04   18.04   -   -
2156   2   68   4.98   200.00   66.35   55.20   0.83
2591   1   1039   0.00   600.00   71.51   73.63   1.03
2591   2   21   0.00   88.09   34.67   30.41   0.88
2592   1   1025   0.00   200.00   23.35   30.69   1.31
2592   2   384   0.00   99.63   14.82   14.81   1.00

 

Note. C_Hole: 1: Channels, 2: Drill holes

 

Table 11-16: Estimation Domain Composite Statistics for Copper (Cu %) 

Nexa Resources S.A. – El Porvenir Mine

 

C_ESTIM   C_Hole   #
Samples
  Min.
(%)
  Max.
(%)
  Mean
(%)
  Std. Dv
(%)
  C.V.
1   1   3024   0.00   2.70   0.27   0.32   1.18
1   2   1426   0.00   6.20   0.23   0.39   1.69
21   1   127   0.01   0.60   0.19   0.16   0.81
21   2   410   0.00   2.00   0.29   0.33   1.14
100   1   1574   0.00   1.30   0.12   0.24   1.93
100   2   2010   0.00   1.41   0.09   0.15   1.71
157   1   59   0.01   1.84   0.35   0.41   1.19
164   1   21   0.16   2.52   0.74   0.55   0.75
164   2   156   0.00   4.36   0.87   0.64   0.73
201   2   8   0.00   0.11   0.03   0.04   1.15
252   1   38   0.05   1.61   0.42   0.42   1.00
252   2   11   0.00   0.40   0.19   0.10   0.51
259   1   2064   0.00   1.60   0.21   0.22   1.04
259   2   405   0.00   4.80   0.45   0.58   1.29
264   2   102   0.01   6.77   0.87   0.75   0.86
307   1   5035   0.00   4.30   0.41   0.40   0.98
307   2   2222   0.00   3.30   0.42   0.48   1.14
350   1   54   0.00   1.10   0.33   0.22   0.68
350   2   196   0.00   2.75   0.41   0.49   1.22
450   1   675   0.01   3.19   0.36   0.35   0.97
450   2   488   0.00   6.14   0.37   0.40   1.06
456   1   14   0.07   1.33   0.51   0.41   0.80
456   2   76   0.00   5.82   0.68   0.89   1.30
458   1   98   0.01   2.93   0.22   0.32   1.46
458   2   220   0.00   3.13   0.29   0.33   1.14
466   1   2784   0.00   2.70   0.15   0.24   1.64
466   2   2547   0.00   4.39   0.26   0.36   1.38

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-55

 

(GRAPHIC)

 

C_ESTIM   C_Hole   #
Samples
  Min.
(%)
  Max.
(%)
  Mean
(%)
  Std. Dv
(%)
  C.V.
671   1   50   0.01   0.25   0.06   0.07   1.15
671   2   1131   0.00   0.18   0.02   0.02   1.48
700   1   202   0.01   0.09   0.02   0.02   0.91
700   2   119   0.00   0.11   0.02   0.02   1.09
701   1   460   0.00   1.61   0.08   0.14   1.73
701   2   853   0.00   0.39   0.04   0.05   1.45
750   1   7   0.02   0.63   0.32   0.19   0.59
750   2   755   0.00   1.00   0.12   0.22   1.83
751   1   45   0.01   0.22   0.04   0.05   1.26
751   2   106   0.00   0.25   0.04   0.06   1.57
756   2   115   0.00   1.60   0.21   0.30   1.40
852   2   51   0.00   2.18   0.55   0.53   0.96
860   1   12   0.00   0.11   0.02   0.03   1.14
860   2   117   0.00   0.85   0.10   0.12   1.20
864   2   30   0.00   2.78   0.38   0.44   1.17
865   2   78   0.00   0.92   0.12   0.13   1.09
883   1   8   0.04   0.12   0.07   0.02   0.37
883   2   21   0.01   0.49   0.18   0.13   0.69
901   1   88   0.01   1.90   0.23   0.33   1.46
901   2   283   0.00   1.71   0.21   0.22   1.07
902   1   21   0.01   0.46   0.08   0.10   1.28
902   2   139   0.00   0.63   0.08   0.08   0.98
1004   1   5   0.02   0.51   0.18   0.17   0.95
1004   2   30   0.05   0.73   0.33   0.20   0.61
1008   1   27   0.01   0.13   0.02   0.03   1.17
1008   2   121   0.00   0.32   0.04   0.06   1.44
1010   1   41   0.00   0.87   0.10   0.17   1.78
1010   2   158   0.00   2.00   0.17   0.24   1.41
1023   1   142   0.01   0.24   0.03   0.04   1.20
1023   2   221   0.00   1.11   0.08   0.13   1.69
1028   1   201   0.01   0.79   0.05   0.07   1.38
1028   2   1303   0.00   0.82   0.09   0.10   1.08
1029   2   172   0.00   2.35   0.25   0.31   1.24
1034   1   36   0.00   0.50   0.05   0.07   1.41
1034   2   593   0.00   0.63   0.07   0.08   1.10
1051   1   202   0.00   1.07   0.13   0.15   1.17
1051   2   628   0.00   1.70   0.11   0.14   1.36
1300   1   1211   0.00   3.70   0.31   0.32   1.02
1300   2   409   0.00   1.88   0.20   0.25   1.25

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-56

 

(GRAPHIC)

 

C_ESTIM   C_Hole   #
Samples
  Min.
(%)
  Max.
(%)
  Mean
(%)
  Std. Dv
(%)
  C.V.
1402   1   119   0.00   2.20   0.29   0.27   0.92
1402   2   2331   0.00   7.05   0.33   0.40   1.22
1404   2   412   0.00   3.24   0.74   0.53   0.72
1408   1   61   0.01   0.65   0.14   0.16   1.17
1408   2   438   0.00   1.60   0.21   0.22   1.02
1450   1   106   0.01   0.35   0.04   0.05   1.30
1450   2   70   0.00   0.23   0.04   0.05   1.29
1455   1   127   0.00   0.30   0.06   0.07   1.15
1455   2   136   0.00   0.21   0.03   0.04   1.34
1458   1   174   0.00   1.47   0.16   0.23   1.41
1458   2   212   0.00   2.35   0.21   0.33   1.53
1502   1   16   0.03   0.59   0.21   0.12   0.61
1502   2   173   0.01   6.96   1.06   0.77   0.72
1504   1   91   0.01   5.12   0.63   0.70   1.11
1504   2   188   0.00   4.36   0.70   0.66   0.94
1607   1   248   0.00   0.37   0.03   0.04   1.33
1607   2   498   0.00   0.67   0.04   0.07   1.51
1614   1   11   0.01   0.13   0.04   0.04   1.02
1614   2   68   0.00   0.39   0.07   0.07   0.97
1650   1   1861   0.00   2.50   0.39   0.35   0.89
1650   2   762   0.00   3.11   0.35   0.36   1.03
1702   1   137   0.01   4.91   0.34   0.48   1.40
1702   2   190   0.00   1.29   0.20   0.20   1.00
1712   1   26   0.01   0.75   0.08   0.15   1.97
1712   2   210   0.00   0.40   0.06   0.07   1.17
1716   1   136   0.00   0.84   0.11   0.14   1.18
1716   2   202   0.00   1.09   0.09   0.14   1.54
1718   1   60   0.00   0.39   0.08   0.08   1.11
1718   2   28   0.00   0.13   0.02   0.04   1.67
1750   1   368   0.00   1.04   0.16   0.18   1.07
1750   2   180   0.00   1.79   0.20   0.33   1.67
1850   1   266   0.00   0.59   0.05   0.08   1.68
1850   2   349   0.00   0.29   0.03   0.04   1.39
1855   1   353   0.00   1.50   0.28   0.27   0.99
1855   2   259   0.00   1.49   0.16   0.18   1.14
1900   1   1354   0.00   0.90   0.07   0.11   1.46
1900   2   724   0.00   0.86   0.05   0.09   1.64
1960   1   266   0.00   0.81   0.15   0.13   0.87
1960   2   107   0.00   0.69   0.08   0.09   1.12

 

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-57

 

(GRAPHIC)

 

C_ESTIM   C_Hole   #
Samples
  Min.
(%)
  Max.
(%)
  Mean
(%)
  Std. Dv
(%)
  C.V.
1965   1   185   0.00   0.68   0.05   0.07   1.50
1965   2   187   0.00   0.14   0.03   0.03   1.19
2051   2   254   0.00   0.94   0.06   0.10   1.61
2060   2   330   0.00   1.32   0.13   0.17   1.29
2065   2   41   0.00   0.93   0.28   0.25   0.89
2067   2   18   0.02   1.28   0.29   0.32   1.10
2069   2   17   0.00   1.02   0.33   0.23   0.70
2072   2   13   0.00   0.17   0.04   0.05   1.20
2073   2   6   0.02   0.21   0.11   0.06   0.55
2079   2   12   0.17   0.93   0.42   0.19   0.45
2104   2   135   0.02   1.90   0.28   0.34   1.25
2156   1   1   0.01   0.01   0.01   -   -
2156   2   68   0.00   0.10   0.02   0.02   1.06
11511   1   267   0.01   0.40   0.14   0.09   0.63
11511   2   1100   0.00   0.86   0.14   0.12   0.88
11512   1   616   0.00   1.20   0.25   0.19   0.77
11512   2   696   0.00   1.86   0.30   0.22   0.75

 

Note. C_Hole: 1: Channels, 2: Drill holes

 

11.9 Trend Analysis

 

11.9.1 Variography

 

Nexa generated downhole and directional variograms using the two metre composite values generated for each domain and each element. The variograms were used to support the characterization and quantification of the variance of mineralization within the spatial continuity of the mineralization domains being analyzed. Variograms were standardized and modelled using two spherical structures in three directions. The variograms were used for OK interpolation and as a guide for selecting search ellipse ranges.

 

Figure 11-13 illustrates an example of the zinc variograms for the 307 Progreso Domain. The results for all modelled variograms for zinc are listed in Table 11-17.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-58

 

(GRAPHIC)

 

(GRAPHIC)

 

Figure 11-13: Zinc Normal Score Experimental and Modelled Variograms for Domain Progreso 307 

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-59

 

(GRAPHIC)

 

Table 11-17:             Zinc Variogram Parameters 

Nexa Resources S.A. – El Porvenir Mine

 

            Datamine Rotation
V-ANGLE
    Rotation System
V-AXIS
    Search Ellipse Structure 1     Search Ellipse Structure 2  
C_ESTIM     Nugget     1     2     3     1     2     3     Var.
Model
Type
    Sill     Major     Minor     Vertical     Var.
Model
Type
    Sill     Major     Minor     Vertical  
  1       0.3       69.00       0.00       65.00       3       2       1       1       0.38       9       6       16       1       0.32       23       31       27  
  100       0.22       92.13       40.24       57.80       3       2       1       1       0.4       50       10       10       1       0.38       98       27       12  
  154       0.34       -139.74       66.80       -58.14       3       2       1       1       0.28       10       5       2       1       0.38       32       16       8  
  157       0.25       -66.51       -4.33       59.91       3       2       1       1       0.51       17       19       1       1       0.24       25       20       15  
  256       0.2       6.55       -9.39       69.72       3       2       1       1       0.09       17       19       1       1       0.71       65       20       15  
  264       0.15       80.00       44.92       85.76       3       2       1       1       0.31       38       16       3       1       0.54       56       36       14  
  270       0.13       146.34       14.94       84.83       3       2       1       1       0.31       23       35       5       1       0.56       99       36       30  
  302       0.16       105.94       9.95       -83.91       3       2       1       1       0.16       46       19       5       1       0.68       63       52       14  
  350       0.07       92.57       38.94       -86.14       3       2       1       1       0.32       19       13       6       1       0.61       45       29       18  
  453       0.2       -74.26       58.53       70.58       3       2       1       1       0.01       23       21       1       1       0.79       60       58       15  
  466       0.15       138.39       73.26       16.91       3       2       1       1       0.41       28       4       11       1       0.44       43       14       13  
  550       0.06       -114.69       48.97       -74.66       3       2       1       1       0.1       91       3       1       1       0.84       94       38       15  
  600       0.23       97.95       72.04       55.73       3       2       1       1       0.01       22       7       8       1       0.76       59       30       17  
  652       0.08       -69.00       18.75       23.86       3       2       1       1       0.08       63       19       1       1       0.84       335       20       15  
  671       0.447       -58.80       18.89       16.69       3       2       1       1       0.05       52       19       1       1       0.503       66       20       15  
  674       0.447       8.80       28.02       -11.17       3       2       1       1       0.01       3       19       1       1       0.543       91       39       15  
  677       0.13       26.69       20.25       -14.97       3       2       1       1       0.33       38       19       1       1       0.54       74       20       15  
  700       0.21       64.36       54.47       126.05       3       2       1       1       0.08       58       19       1       1       0.71       59       20       15  
  750       0.39       -97.53       35.63       -58.67       3       2       1       1       0.19       6       5       1       1       0.42       34       17       20  
  751       0.39       -175.98       74.21       -108.68       3       2       1       1       0.01       47       47       1       1       0.6       106       50       20  
  860       0.39       68.49       39.93       -86.09       3       2       1       1       0.19       6       5       1       1       0.42       20       20       20  

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-60

 

(GRAPHIC)

 

            Datamine Rotation
V-ANGLE
    Rotation System
V-AXIS
    Search Ellipse Structure 1     Search Ellipse Structure 2  
C_ESTIM     Nugget     1     2     3     1     2     3     Var.
Model
Type
    Sill     Major     Minor     Vertical     Var.
Model
Type
    Sill     Major     Minor     Vertical  
  865       0.39       -124.18       39.82       -83.49       3       2       1       1       0.01       20       5       1       1       0.6       20       20       20  
  872       0.17       -119.13       -4.92       -79.96       3       2       1       1       0.07       19       5       1       1       0.76       20       20       20  
  901       0.19       -179.12       -9.96       95.08       3       2       1       1       0.11       22       8       2       1       0.7       167       88       28  
  908       0.13       78.26       78.83       26.30       3       2       1       1       0.06       10       7       5       1       0.81       40       22       13  
  950       0.08       -54.42       49.34       -77.67       3       2       1       1       0.57       86       61       1       1       0.35       92       66       20  
  1008       0.39       -144.18       39.82       -83.49       3       2       1       1       0.19       6       5       1       1       0.42       20       20       20  
  1016       0.39       -77.34       -14.77       -79.66       3       2       1       1       0.19       6       5       1       1       0.42       20       20       20  
  1019       0.26       -171.00       50.00       90.00       3       2       1       1       0.32       6       5       1       1       0.42       20       20       20  
  1026       0.39       91.26       19.74       80.43       3       2       1       1       0.19       15       12       1       1       0.42       43       24       9  
  1028       0.39       104.93       34.39       77.85       3       2       1       1       0.01       64       16       1       1       0.6       93       30       20  
  1029       0.21       -129.68       19.47       -76.20       3       2       1       1       0.37       6       5       1       1       0.42       20       20       20  
  1034       0.11       -5.41       54.01       -105.44       3       2       1       1       0.11       7       22       4       1       0.78       46       125       12  
  1208       0.39       125.19       14.67       77.59       3       2       1       1       0.07       79       28       1       1       0.54       134       33       20  
  1300       0.26       115.03       59.88       38.86       3       2       1       1       0.55       13       12       1       1       0.19       34       17       20  
  1350       0.14       -78.46       59.94       94.00       3       2       1       1       0.18       36       5       6       1       0.68       40       24       22  
  1402       0.39       -84.87       14.89       97.24       3       2       1       1       0.11       34       5       4       1       0.5       60       41       14  
  1408       0.22       130.47       69.41       75.65       3       2       1       1       0.25       42       37       1       1       0.53       71       41       20  
  1410       0.21       -105.41       42.82       -67.93       3       2       1       1       0.02       33       5       1       1       0.77       48       28       20  
  1450       0.39       -109.25       34.51       -79.06       3       2       1       1       0.01       6       44       1       1       0.6       55       53       20  
  1452       0.39       -108.63       24.60       -78.99       3       2       1       1       0.12       45       5       1       1       0.49       76       75       20  
  1458       0.09       -20.00       60.00       90.00       3       2       1       1       0.25       28       20       3       1       0.66       34       21       13  
  1504       0.06       152.23       9.93       -97.11       3       2       1       1       0.37       9       7       3       1       0.57       40       26       12  
  1555       0.39       -79.05       -72.04       -55.73       3       2       1       1       0.1       25       12       2       1       0.51       34       31       7  
  1558       0.11       81.90       38.96       74.49       3       2       1       1       0.01       9       5       14       1       0.88       34       24       21  

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-61

 

(GRAPHIC)

 

            Datamine Rotation
V-ANGLE
    Rotation System
V-AXIS
    Search Ellipse Structure 1     Search Ellipse Structure 2  
C_ESTIM     Nugget     1     2     3     1     2     3     Var.
Model
Type
    Sill     Major     Minor     Vertical     Var.
Model
Type
    Sill     Major     Minor     Vertical  
  1607       0.24       -115.26       19.74       -80.43       3       2       1       1       0.01       23       24       1       1       0.75       72       28       20  
  1614       0.39       65.00       70.00       -90.00       3       2       1       1       0.01       20       5       1       1       0.6       20       20       20  
  1650       0.16       91.00       83.00       0.00       3       2       1       1       0.35       10       4       4       1       0.49       26       29       18  
  1702       0.28       52.42       65.19       51.92       3       2       1       1       0.02       19       16       1       1       0.7       89       17       20  
  1712       0.39       -124.00       10.00       -90.00       3       2       1       1       0.01       25       5       1       1       0.6       33       20       20  
  1714       0.39       114.03       59.88       38.86       3       2       1       1       0.19       6       5       1       1       0.42       20       20       20  
  1718       0.09       -99.00       70.00       90.00       3       2       1       1       0.01       47       5       1       1       0.9       56       20       20  
  1754       0.39       -46.00       40.00       -90.00       3       2       1       1       0.11       21       38       1       1       0.5       92       45       20  
  1850       0.19       -71.00       70.00       -90.00       3       2       1       1       0.62       10       5       1       1       0.19       34       17       20  
  1855       0.25       -45.40       64.83       97.07       3       2       1       1       0.28       54       5       6       1       0.47       55       17       20  
  1900       0.05       -77.05       72.04       -124.27       3       2       1       1       0.14       5       6       2       1       0.81       48       11       11  
  1950       0.39       66.09       -19.97       -86.81       3       2       1       1       0.27       19       13       1       1       0.34       34       23       8  
  1959       0.16       -110.00       -15.00       -90.00       3       2       1       1       0.01       4       12       15       1       0.83       38       29       26  
  1965       0.11       -114.38       49.96       93.11       3       2       1       1       0.09       27       17       4       1       0.8       46       30       14  
  2000       0.35       29.81       18.30       162.67       3       2       1       1       0.21       21       5       1       1       0.44       41       23       11  
  2051       0.36       -136.12       9.96       -95.08       3       2       1       1       0.01       29       5       1       1       0.63       51       39       20  
  2060       0.39       95.93       59.62       171.42       3       2       1       1       0.32       33       17       1       1       0.29       46       29       20  
  2100       0.15       146.00       40.00       -90.00       3       2       1       1       0.23       7       5       4       1       0.62       37       20       20  
  2150       0.39       16.33       35.63       160.48       3       2       1       1       0.01       53       5       1       1       0.6       63       17       20  
  2156       0.39       -49.32       -27.03       142.55       3       2       1       1       0.19       6       5       1       1       0.42       20       11       5  
  201       0.5       70.00       75.00       90.00       3       2       1       1       0.02       3       19       1       1       0.48       20       20       20  
  250       0.3       -141.19       14.67       -77.59       3       2       1       1       0.22       10       13       6       1       0.48       74       29       9  
  306       0.25       -90.00       90.00       175.00       3       2       1       1       0.36       5       3       1       1       0.39       49       18       15  
  307       0.17       129.12       -9.96       84.92       3       2       1       1       0.17       4       8       3       1       0.65       47       23       11  

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-62

 

(GRAPHIC)

 

            Datamine Rotation
V-ANGLE
    Rotation System
V-AXIS
    Search Ellipse Structure 1     Search Ellipse Structure 2  
C_ESTIM     Nugget     1     2     3     1     2     3     Var.
Model
Type
    Sill     Major     Minor     Vertical     Var.
Model
Type
    Sill     Major     Minor     Vertical  
  458       0.31       85.00       30.00       -90.00       3       2       1       1       0.48       75       31       8       1       0.21       82       55       24  
  701       0.16       -70.34       15.76       37.25       3       2       1       1       0.38       8       7       8       1       0.46       44       10       12  
  756       0.23       85.98       74.21       -71.32       3       2       1       1       0.59       30       5       1       1       0.17       34       17       20  
  800       0.08       -177.27       19.99       87.87       3       2       1       1       0.44       37       19       1       1       0.47       40       26       14  
  850       0.44       -125.25       38.38       -70.72       3       2       1       1       0.2       6       5       1       1       0.36       20       20       20  
  883       0.41       111.48       35.63       -58.67       3       2       1       1       0.19       6       5       1       1       0.4       20       20       20  
  1054       0.43       -112.28       37.43       -65.80       3       2       1       1       0.19       6       5       1       1       0.39       20       20       20  
  1609       0.34       -125.85       69.62       -78.45       3       2       1       1       0.13       46       26       1       1       0.52       80       51       20  
  1755       0.5       -31.85       34.94       -56.37       3       2       1       1       0.18       6       5       1       1       0.32       20       20       20  
  2065       0.42       108.02       74.21       71.32       3       2       1       1       0.19       6       5       1       1       0.38       30       20       20  
  2067       0.48       -86.18       39.82       -83.49       3       2       1       1       0.19       6       5       1       1       0.32       20       20       20  
  2072       0.46       -9.18       39.82       -83.49       3       2       1       1       0.19       6       5       1       1       0.35       20       20       20  
  2073       0.44       -95.82       39.82       -96.52       3       2       1       1       0.19       6       5       1       1       0.38       20       20       20  
  2079       0.44       -134.89       -3.21       3.83       3       2       1       1       0.18       6       5       1       1       0.38       20       20       20  
  2104       0.22       92.00       70.00       0.00       3       2       1       1       0.27       82       5       1       1       0.51       94       66       20  
  4501       0.06       -105.79       24.85       -83.39       3       2       1       1       0.6       6       4       5       1       0.35       18       21       16  
  4502       0.06       -105.79       24.85       -83.39       3       2       1       1       0.6       6       4       5       1       0.35       18       27       16  
  259       0.08       99.06       31.03       59.23       3       2       1       1       0.51       6       6       6       1       0.41       57       34       30  
  17501       0.06       -25.81       -34.78       -82.69       3       2       1       1       0.69       14       17       5       1       0.25       40       51       8  
  17502       0.06       -25.81       -34.78       -82.69       3       2       1       1       0.45       16       59       5       1       0.49       31       131       8  
  1151       0.06       116.26       58.39       49.26       3       2       1       1       0.38       8       31       4       1       0.56       42       114       58  
  21       0.22       92.133       40.239       57.803       3       2       1       1       0.4       50       10       10       1       0.38       98       27       12  

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-63

 

(GRAPHIC)

 

11.10 Search Strategy and Grade Interpolation Parameters

 

Grades were interpolated into blocks on a parent cell basis using OK for a small number of domains with sufficient data and reasonable modelled variograms. For the other domains, ID³ interpolation method was used. All the variables, Zn, Cu, Pb, and Ag, were interpolated, and estimates were not density weighted. All directions were based on Datamine’s dynamic anisotropy, which varies search ellipsoid orientations according to the trend of the mineralization domain.

 

The grade estimation was completed in three passes. Pass 1 uses a search radius equal to the variogram range; Pass 2 uses a search radius equal to 1.5 to 2.5 times the range of Pass 1; and Pass 3 uses a search radius of 10 times the range of Pass 1.

 

The search criteria for the largest contributor domains for the Mineral Resource and the Mineral Reserve are listed in Table 11-18 for zinc estimates and in Table 11-19 for silver estimates.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-64

 

  (GRAPHIC)

 

Table 11-18:               Zinc Estimation Parameters

Nexa Resources S.A. – El Porvenir Mine

 

Individual Mineralization     COD_OB     Grade           Rotation
 S-AXIS
    Ellipse
 S-DIST 2
    Pass 1     # Comp     Pass 2     # Comp     Pass 3     # Comp     Max Comp.  
Domain (COD_OB)     Code     Domain     Method     1     2     3     1       3     SVOLFAC     Min     Min     SVOLFAC     Min     Max     SVOLFAC     Min     Max     Per Hole  
  701       de2               IDW3       3       2       1       40.00       9.00       11.00       1       8       10       2.5       8       10       10       1       3       2  
  2100       dl01               IDW3       3       2       1       36.00       18.00       10.00       1       8       10       2       4       6       10       2       6       2  
  2104       dl05               IDW3       3       2       1       20.00       15.00       8.00       1       8       10       2       4       6       10       2       4       2  
  2110       dl11               IDW3       3       2       1       33.00       18.00       18.00       1       8       10       2       4       6       10       2       6       2  
  1500       exiti1               IDW3       3       2       1       36.00       18.00       10.00       1       10       14       2       7       10       10       1       7       2  
  1403       exitoa               IDW3       3       2       1       36.00       22.00       20.00       1       8       10       2       4       6       10       2       6       2  
  1404       exitob               IDW3       3       2       1       36.00       18.00       8.00       1       8       10       2       4       6       10       2       4       2  
  1402       exito               IDW3       3       2       1       36.00       18.00       10.00       1       8       10       2       4       6       10       2       6       2  
  21       por9cf1               IDW3       3       2       1       25.00       20.00       10.00       1       4       12       2       4       6       10       2       4       2  
  465       por9o               IDW3       3       2       1       53.00       27.00       15.00       1       8       10       2       4       6       10       2       6       2  
  466       por9p               IDW3       3       2       1       39.00       13.00       12.00       1       8       10       2       4       6       10       2       6       2  
  467       por9q               IDW3       3       2       1       39.00       13.00       12.00       1       8       10       2       4       6       10       2       6       2  
  468       por9r               IDW3       3       2       1       53.00       27.00       15.00       1       6       12       3       6       12       10       4       8       3  
  469       por9s               IDW3       3       2       1       53.00       27.00       15.00       1       8       10       2       4       6       10       2       6       2  
  471       por9u               IDW3       3       2       1       53.00       27.00       15.00       1       8       10       2       4       6       10       2       6       2  
  450       por9       Low Grade       IDW3       3       2       1       16.00       19.00       14.00       1       8       10       1.5       4       6       10       2       6       2  
  450       por9       High Grade       IDW3       3       2       1       16.00       24.00       14.00       1       8       10       1.5       4       6       10       2       6       2  
  500       porv9a               OK       3       2       1       39.00       13.00       12.00       1       8       10       2       4       6       10       2       6       2  
  350       porv9e               IDW3       3       2       1       41.00       26.00       16.00       1       8       10       2       4       6       10       2       6       2  
  550       porv9w               IDW3       3       2       1       85.00       34.00       14.00       1       8       10       2       4       6       10       2       6       2  
  2150       sara1               IDW3       3       2       1       36.00       18.00       10.00       1       8       10       2       7       10       10       2       6       2  
  2151       sara2               IDW3       3       2       1       34.00       16.00       10.00       1       7       10       2       4       7       15       2       5       2  
  2152       sara3               IDW3       3       2       1       36.00       18.00       10.00       1       8       10       2       6       7       25       2       5       2  
  259       v12i1               IDW3       3       2       1       51.00       31.00       27.00       1       8       10       1.5       4       6       10       2       6       2  
  950       v12ne               IDW3       3       2       1       83.00       59.00       18.00       1       8       10       2       4       6       10       2       6       2  
  1024       v12s33               IDW3       3       2       1       84.00       27.00       18.00       1       8       10       2       4       6       10       2       6       2  
  1650       v5i               OK       3       2       1       32.00       16.00       10.00       1       10       14       2       5       9       10       2       4       2  
  1754       v5ne5               IDW3       3       2       1       24.00       12.00       8.00       1       7       9       1.5       4       6       10       2       3       2  
  51       vc1b               IDW3       3       2       1       29.00       14.00       7.00       1       8       10       2       4       6       10       1       3       2  
  100       vc31               IDW3       3       2       1       88.00       24.00       11.00       1       8       10       2       4       6       10       2       6       2  
  1051       vcarmn               IDW3       3       2       1       29.00       14.00       7.00       1       8       10       2       4       6       10       2       6       2  
  1154       vcn32               IDW3       3       2       1       29.00       14.00       7.00       1       8       10       2       4       6       10       2       6       2  
  1255       vcn3w6               IDW3       3       2       1       31.00       28.00       6.00       1       8       10       2       4       6       10       2       6       2  
  1257       vcn3w8               IDW3       3       2       1       31.00       28.00       6.00       1       8       10       2       4       6       10       2       6       2  
  1151       vcn3               IDW3       3       2       1       38.00       103.00       52.00       1       8       10       1.5       4       6       10       2       6       2  
  307       vprg               IDW3       3       2       1       42.00       21.00       10.00       1       8       10       2       4       6       10       2       6       2  

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-65

 

(GRAPHIC)

 

Table 11-19:                  Silver Estimation Parameters
Nexa Resources S.A. – El Porvenir Mine

 

Individual Mineralization     COD_OB     Grade           Rotation
S-AXIS
    Ellipse  
S-DIST 2
    Pass 1     # Comp     Pass 2     # Comp     Pass 3     # Comp     Max Comp.  
  Domain (COD_OB)        Code        Domain        Method        1       2       3       1               3       SVOLFAC         Min         Min         SVOLFAC        Min         Max          SVOLFAC        Min        Max         Per Hole    
  701       de2               IDW3       3       2       1       34.00       18.00       9.00       1       8       12       2.5       8       12       10       1       3       2  
  2100       dl01               IDW3       3       2       1       36.00       18.00       10.00       1       8       10       2       4       6       10       2       6       2  
  2104       dl05               IDW3       3       2       1       36.00       18.00       10.00       1       8       10       2       4       6       10       2       6       2  
  2110       dl11               IDW3       3       2       1       59.00       28.00       14.00       1       8       10       2       4       6       10       2       6       2  
  1500       exiti1               IDW3       3       2       1       36.00       18.00       10.00       1       10       14       2       7       10       10       1       7       2  
  1403       exitoa               IDW3       3       2       1       31.00       17.00       7.00       1       8       10       2       4       6       10       2       6       2  
  1404       exitob               IDW3       3       2       1       36.00       18.00       8.00       1       8       10       2       4       6       10       2       4       2  
  1402       exito               IDW3       3       2       1       36.00       18.00       10.00       1       8       10       2       4       6       10       2       6       2  
  21       por9cf1               IDW3       3       2       1       36.00       18.00       10.00       1       4       12       2       4       6       10       2       4       2  
  465       por9o               IDW3       3       2       1       13.00       8.00       24.00       1       8       10       2       4       6       10       2       6       2  
  466       por9p               IDW3       3       2       1       13.00       8.00       24.00       1       8       10       2       4       6       10       2       6       2  
  467       por9q               IDW3       3       2       1       13.00       8.00       24.00       1       8       10       2       4       6       10       2       6       2  
  468       por9r               IDW3       3       2       1       71.00       44.00       23.00       1       6       12       3       6       12       10       4       8       3  
  469       por9s               IDW3       3       2       1       71.00       44.00       23.00       1       8       10       2       5       6       10       2       6       2  
  471       por9u               IDW3       3       2       1       71.00       44.00       23.00       1       8       10       2       4       6       10       2       6       2  
  450       por9               IDW3       3       2       1       22.00       17.00       17.00       1       8       10       1.5       4       6       10       2       6       2  
  500       porv9a               IDW3       3       2       1       71.00       44.00       23.00       1       8       10       2       4       6       10       2       6       2  
  350       porv9e               IDW3       3       2       1       25.00       15.00       9.00       1       8       10       2       4       6       10       2       6       2  
  550       porv9w               IDW3       3       2       1       71.00       44.00       23.00       1       8       10       2       8       10       10       1       3       2  
  2150       sara1               IDW3       3       2       1       36.00       18.00       10.00       1       8       10       2       7       10       10       2       6       2  
  2151       sara2               IDW3       3       2       1       34.00       16.00       10.00       1       7       10       2       4       7       15       2       5       2  
  2152       sara3               IDW3       3       2       1       36.00       18.00       10.00       1       8       10       2       6       7       25       2       5       2  
  259       v12i1       c estim 2591 (High Grade)       IDW3       3       2       1       35.00       20.00       10.00       1       8       10       1.3       4       6       10       2       6       2  
  259       v12i1       c estim 2592 (Low Grade)       IDW3       3       2       1       35.00       20.00       10.00       1       8       10       1.3       4       6       10       2       6       2  
  950       v12ne               IDW3       3       2       1       25.00       29.00       13.00       1       8       10       2       4       6       10       2       6       2  
  1024       v12s33               IDW3       3       2       1       68.00       36.00       21.00       1       8       10       2       4       6       10       2       6       2  
  1650       v5i               OK       3       2       1       32.00       16.00       10.00       1       10       14       2       5       9       10       2       4       2  
  1754       v5ne5               IDW3       3       2       1       24.00       12.00       8.00       1       7       9       1.5       4       6       10       2       3       2  
  51       vc1b               IDW3       3       2       1       57.00       28.00       10.00       1       8       10       2       4       6       10       1       3       2  
  100       vc31               IDW3       3       2       1       32.00       18.00       11.00       1       8       10       2       4       6       10       2       6       2  
  1051       vcarmn               IDW3       3       2       1       70.00       39.00       22.00       1       8       10       2       4       6       10       2       6       2  
  1154       vcn32               IDW3       3       2       1       59.00       23.00       10.00       1       8       10       2       4       6       10       2       6       2  
  1255       vcn3w6               IDW3       3       2       1       57.00       28.00       10.00       1       8       10       2       4       6       10       2       6       2  
  1257       vcn3w8               IDW3       3       2       1       57.00       28.00       10.00       1       8       10       2       4       6       10       2       6       2  
  1151       vcn3               IDW3       3       2       1       98.00       75.00       14.00       1       8       10       1.5       4       6       10       2       6       2  
  307       vprg               IDW3       3       2       1       115.00       32.00       37.00       1       8       10       2       4       6       10       2       6       2  

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-66

 

(GRAPHIC)  

 

11.11 Bulk Density

 

A total of 1,131 density measurements were taken within 191 mineralization domains. Nexa grouped individual mineralization domains by rock and mineralization style and defined density domains (Figure 11-14). Table 11-20 shows the statistics of all of the density data for each density domain and the density sample location is shown in Figure 11-15. Nexa assigned the mean density values to their respective density domains. In areas without or little density data, Nexa assigned either the average density for the deposit (3.42 g/cm3) or a density value from a nearby density domain with similar mineralization and rock type.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

11-67

 

(GRAPHIC)  

 

Table 11-20:           Density Data Statistics

Nexa Resources S.A. – El Porvenir Mine 

 

C_DENS   COB_OB  

No.

amples

  (g/cm3)   (g/cm3)   (g/cm3)
100   am1,am12,am14,am16,am17,am20,am21,am23,am3,am4,am8,am9, amsk1,amsk10,amsk11,amsk13,amsk14,amsk15,amsk16,amsk17,amsk18, amsk2,amsk3,amsk4,amsk5,amsk6,amsk7,amsk8,amsk9   47   3.16   3.88   3.51
102   v5nw13,v5nw14,v5nw15,v5nw16,v5nw18,v5nw19,v5nw20,v5nw21   9   2.66   3.34   2.96
103   dl01,dl02,dl03,dl04,dl05,dl06,dl07,dl08,dl09,dl10,dl11   37   2.89   3.94   3.34
104   cpoex1,cpoex2,exit10,exit11,exit12,exit13,exit16,exit17,exit18,exiti1, exiti2,exiti3,exiti4,exiti5,exiti6,exiti7,exito,exito1,exito2,exito3,exito4,exito5,e xito6,exito7,exito8,exito9,exitoa,exitob,exitoc,exitod,exits,exits1,exits2,exits3 ,exits 4,exits5,exits6,exits7,exits8   134   2.82   3.9   3.39
105   int10,int,int9,ints1,ints10,ints11,ints12,ints13,ints14,ints15,ints16, ints17,ints21,ints22,ints23,ints24,ints25,ints26,ints28,ints29,ints3,ints31,ints 32,ints4,ints5,ints6,ints7   29   2.75   3.5   3.13
106   p2se1,p2se10,p2se11,p2se12,p2se13,p2se14,p2se15,p2se16,p2se17, p2se18,p2se2,p2se3,p2se4,p2se5,p2se6,p2se7,p2se,p2sr,por2sd   43   2.62   2.94   2.78
107   p2sw1 ,p2sw10,p2sw11,p2sw12,p2sw13,p2sw14,p2sw15,p2sw16, p2sw17,p2sw18,p2sw19,p2sw2,p2sw20,p2sw21,p2sw22,p2sw23,p2sw24,p 2sw25,p2sw26,p2sw27,p2sw28,p2sw29,p2sw3,p2sw4,p2sw5,p2sw6,p2sw7 ,p2sw8 ,p2sw9   22   2.57   2.82   2.68
108   por9_1,por9_2 ,por91,por92,por93,por94,por95,por96,por97,por98, por9a,por9b,por9c,por9cf1,por9cf2,por9cf3,por9cf4,por9cf5,por9cf6,por9cf7 ,por9 cf8,por9e,por9f,por9g,por9h,por9i,por9j,por9l,por9m,por9n,por9o,por9 p,por9q,por9r,por9s,por9t,por9u,por9v,por9w,por9x,por9y,por9z,porv9a,por v9e,porv9f,porv9w,porv9x   85   2.87   3.65   3.21
109   de1,de2,de3,de4,de5,sara1,sara2,sara3,sara4,sara5,sara6,saras1 ,saras2,saras3,saras4,saras5,saras6   63   2.41   2.81   2.6
110   soc21,soc210,soc211,soc212,soc213,soc214,soc22,soc23,soc24,soc25, soc27,soc28,soc29,soc41,soc410,soc411,soc412,soc413,soc414,soc42,so c43,soc434,soc435,soc436,soc437,soc44,soc45,soc46,soc47,soc48,soc49   44   2.7   3.62   3.15
111   v5i,v5ne1,v5ne2,v5ne3,v5ne4,v5ne5,v5ne6,v5nw1,v5nw10,v5nw11, v5nw12,v5nw17,v5nw2,v5nw3,v5nw4,v5nw5,v5nw6,v5nw7,v5nw8,v5nw9,   41   2.85   3.94   3.46
112   v12i1 ,v12i10,v12i11,v12i12,v12i13,v12i14,v12i15,v12i16,v12i17,v12i18, v12i1a,v12i1b,v12i1c,v12i1d,v12i2,v12i3,v12i4,v12i5,v12i6,v12i7,v12i8,v12i   54   3.41   4.16   3.75
113   v12 ,v122,v123,v125,v1252,v126,v127,v12ne   13   2.72   3.45   3.09
114   v12s1 ,v12s10,v12s11,v12s12,v12s13,v12s14,v12s15,v12s16,v12s17, v12s18,v12s19,v12s2,v12s21,v12s22,v12s23,v12s24,v12s25,v12s26,v12s2 7,v12s28,v12s29,v12s3,v12s30,v12s31,v12s32,v12s33,v12s34,v12s35,v12 s36,v12s37,v12s4,v12s5,v12s6,v12s7,v12s8,v12s9,   69   2.72   3.73   3.12
115   vc1 ,vc1a,vc1b,vc1c   17   3.27   4.23   3.77
116   vc21 ,vc214,vc215,vc216,vc217,vc222,vc224,vc24,vc26,vc2922   58   2.77   4.15   3.39
117   vc31,vc32,vc33,vc34,vc35,   41   3   4.38   3.5
118   cn3ei1,cn3ei2,vcn3_1,vcn3_2,vcn32,vcn324,vcn327,vcn3e1,vcn3e3,vcn3e6 , vcarmn,vcn12,vcn13,vcn14,vcn15,vcn16,vcn17,vcn18,   133   2.94   4.22   3.59
119   vcn41,vcn42,vcn43,vcn44,vcn45,vcn46,vcn4i,   42   2.79   4.34   3.58
120   vpor31,vpor32,vpor33,vpor34,vpor35,vpor36,vpor37,vpor38,   22   2.72   3.67   3.15
121   vprg ,vprg1,vprg2,vprg3,vprg4,vprg5,vprg6,vprgb,vprgb1,vprgb2,vprgb3,   8   2.79   3.12   2.93
122   vprgb4,vprgb5,vprgb6,vprgb7,vprgb8,vprgb9,vprgba,vprgbb,   120   2.9   4.34   3.58
Grand Total   1,131   2.41   4.38   3.33

 

 

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Figure 11-14:               3D View of Density Domains

 

 

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Figure 11-15:          3D View of Density Values

 

 

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The SLR QP generated statistics based on mineralized zones and density domains to review the assigned density values and is of the opinion that the density values are reasonable and acceptable. The SLR QP recommends taking more density measurements in areas that currently have insufficient density tests available, particularly in areas within the Mineral Resource and Mineral Reserve shapes.

 

11.12 Block Models

 

Mineralization wireframes were filled with blocks in Datamine Studio RM. The block model was sub-celled at wireframes boundaries with parent cells measuring 4 m by 4 m by 4 m and minimum sub-cell sizes of 0.5 m by 0.5 m by 0.5 m. The block model setup is shown in Table 11-21.

 

Table 11-21:          Block Model Setup 

Nexa Resources S.A. – El Porvenir Mine

 

Parameter   East (m)   North (m)   Elevation (m)
Minimum Coordinate   366,300   8,826,200   2,398
Maximum Coordinate   368,700   8,831,156   4,702
Block size   4   4   4
Min. Sub Block size   0.5   0.5   0.5

 

The SLR QP is of the opinion that the block size is appropriate, based on the drill spacing and proposed mining method, and is suitable to support the estimation of Mineral Resources and Mineral Reserves.

 

11.13 Net Smelter Return and Cut-Off Value

 

An NSR value was determined using the Mineral Resource metal prices, metallurgical recoveries, transport, treatment, and refining costs. Metal prices used for Mineral Resources are based on consensus, long term forecasts from banks, financial institutions, and other sources. The NSR value is expressed as US$/t and is calculated for Mineral Resources to make an adequate comparison with production costs in order to determine whether the mineralized material can be economically mined.

 

The Mine currently produces zinc concentrate with contained silver, lead concentrate with contained silver and gold, and copper concentrate with contained silver and gold as sellable products. The payable metals in concentrates include the applicable concentrate treatment, transportation, refining charges, deductions and penalty elements, according to sales agreements signed between mines and smelters or traders.

 

The smelter terms and metal prices used to determine NSR factors are provided in Table 11-22. The prices are based on 10 year average of the London Metal Exchange (LME) projected prices. The smelter terms are effective as of October 2020.

 

Table 11-22:            NSR Data 

Nexa Resources S.A. – El Porvenir Mine

 

Item   Units   Value
         
Net Metallurgical Recovery *
Zn   %   89.60
Pb   %   79.21

 

 

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Item   Units   Value  
Cu   %     14.29  
Ag   %     62.90  
Cu Concentrate Payable %            
Cu   %     96.7  
Ag   %     90  
Pb Concentrate Payable %            
Pb   %     95  
Ag   %     95  
Zn Concentrate Payable %            
Zn   %     94.6  
Ag   %     70  
Metal Prices            
Zn   US$/lb     1.30  
Pb   US$/lb     1.02  
Cu   US$/lb     3.37  
Ag   US$/oz     19.38  
Logistics and TC            
Zn Concentrate   US$/t conc   $ 295  
Pb Concentrate   US$/t conc   $ 266  
Cu Concentrate **   US$/t conc   $ 279  
Integrated Zn            
Conversion Cost   US$/t Zn prod   $ 452  
Premium   US$/t Zn Prod   $ 173  
Refining Cost            
Au in Pb conc   US$/oz   $ 10.00  
Ag in Pb conc   US$/oz   $ 1.00  
Ag in Cu conc   US$/oz   $ 0.50  

 

* Based on LOM average metal grades  
** Included a 16.68 USD/t penalty

 

Nexa reviewed supply and demand projections for zinc, lead, and copper, as well as consensus long term (ten year) metal price forecasts. SLR verified that Nexa’s selected metal prices for estimating Mineral Reserves are in line with independent forecasts from banks and other lenders. Prices selected for Mineral Resource estimation are 15% higher, which is in line with typical industry practice.

 

The average NSR factors are calculated using the LOM revenue contribution from each metal net of off-site costs and factors, divided by the reserve grade for that metal, and are indicative of the relative contribution of each metal unit to the economics of the mine. For most metals, a variable recovery (as a function of head grade) was used, and therefore the average NSR factors should not be applied to head grades without considering the head grade versus recovery relationship.

 

 

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Metallurgical recoveries used for Mineral Resources are based on historical data which have been consolidated by Nexa as head grade vs. recovery curves shown in Figure 11-16, Figure 11-17, and Figure 11-18. These curves are developed by regression on data set of historical performance.

  

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Figure 11-16:                  Zinc Recovery Curve

 

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Figure 11-17:              Lead Recovery Curve

 

 

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Figure 11-18:               Copper Recovery Curve

 

Several cut-off NSR values (or cut-off grades) have been calculated for El Porvenir dependent on the mining zone and mining method. Each zone has a different material movement cost depending on whether truck haulage, shaft, or a combination of the two is used. Break-even cut-off grade includes direct and indirect mining costs, processing costs, and general and administrative (G&A) as shown in Table 11-23.

 

Table 11-23:                Cut-Off Grade Calculation by Mining Zone and Method 

Nexa Resources S.A. – El Porvenir Mine

 

Item   Units   C&F
Upper Zone        
Mine Cost   US$/t   42.26
Development   US$/t   13.82
Plant Costs   US$/t   10.50
G&A   US$/t   7.30
Cut-Off Grade   US$/t   60.06
         
Intermediate Zone        
Mine Cost   US$/t   43.29
Development   US$/t   13.82
Plant Costs   US$/t   10.50
G&A   US$/t   7.30

 

 

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Item   Units   C&F
Cut-Off Grade   US$/t   61.09
         
Lower Zone        
Mine Cost   US$/t   41.95
Development   US$/t   13.82
Plant Costs   US$/t   10.50
G&A   US$/t   7.30
Cut-Off Grade   US$/t   59.75
         
Mine Deepening Zone        
Mine Cost   US$/t   45.57
Development   US$/t   13.82
Plant Costs   US$/t   10.50
G&A   US$/t   7.30
Cut-Off Grade   US$/t   63.37

 

Mining costs have been reviewed, and SLR considers that the operating costs are reasonable for this type of operation and mining methods.

 

11.14 Classification

 

Definitions for resource categories used in this report are those defined by SEC in S-K 1300. Mineral Resources are classified into Measured, Indicated, and Inferred categories.

 

Blocks were classified as Measured, Indicated, and Inferred based on drill hole spacing requirements determined from global variograms for the mineralization domains with a combination of the number of holes. Three classification groups were defined based on geology, grade continuity, and volume. Separate classification interpolation passes were run to flag the resource categories for each group. Flagging of the blocks by drill hole spacing was done by using a search pass with dimensions as described in Table 11-25.

 

The first pass involved a numerical block classification based on the number of drill holes and search radii in Table 11-25 followed by a post processing of the classification to remove isolated blocks to avoid the “spotted dog” effect and to demonstrate continuity between samples.

 

The classification of the Mineral Resource estimate was applied as follows:

 

Measured Mineral Resources: Measured blocks were defined, using criteria as defined in Table 11-25, and supported with data of a low level of uncertainty as follows:

 

Drilling, sampling, and sample preparation and assay procedures: follow industry standards and best practices.

 

 

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Reliability of sampling data: Good database integrity and representativity based on SLR’s independent data verification and validation, as well as no significant bias observed in QA/QC analysis results.

 

Confidence in interpretation and modelling of geological and estimation domains: The drill hole spacing is sufficient to confirm the location and continuity of the geological and estimation domain wireframes and has been confirmed by underground mapping in places at Veta Carmen Norte 3, Exito, Socorro 2 and 4, and Carmen Norte 1, and Veta Carmen Norte 1.

 

Geology and grade continuity: Based on drilling and underground mapping, trend analysis and variography show reasonable geology and grade continuity.

 

Confidence in estimation of block grades for the main metals: Block grades correlate well with composite data, statistically and spatially, locally and globally.

 

Acceptable bulk density representativity: Sufficient density measurements have been taken for the main domains.

 

Well supported drilling spacing criteria: Block grade interpolations are based on a minimum of three drill holes using search radii that are based on reasonable variograms ranges.

 

Indicated Mineral Resources: Indicated blocks were defined, using criteria as defined in Table 11-25, and supported with data of a low and/or medium level of uncertainty as follows:

 

Drilling, sampling, and sample preparation and assay procedures: follow industry standards and best practices.

 

Reliability of sampling data: Acceptable database integrity and representativity based on SLR’s independent data verification and validation, as well as no significant bias observed in QA/QC analysis results.

 

Confidence in interpretation and modelling of geological and estimation domains: The drill spacing is sufficient to assume the locations and continuity of grade. Most of the main domains (Veta Carmen Norte 3, Porvenir 9, Progreso, and Sara) show good agreement with the drill holes or/and underground mapping and some minor domains show relatively acceptable agreement with the drill holes and underground mapping where the density of drill holes is less, particularly at the mineralization edges.

 

Geology and Grade Continuity: Based on drilling and underground mapping, trend analysis and variography, main domains show reasonable geology and grade continuity.

 

Confidence in estimation of block grades for the main metals: Block grades correlate well with composite data, statistically and spatially, locally and globally.

 

Acceptable bulk density representativity: Sufficient density measurements were taken for most of the main domains, and reasonable density measurements for some of the domains with limited density measurements available at some of the mineralization edges.

 

Well supported drilling spacing criteria: Block grade interpolations are based on a minimum of three drill holes using search radii that are based on reasonable variograms ranges.

 

 

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Inferred Mineral Resources: Inferred blocks were defined, using criteria as defined in Table 11-24 and supported with data of a low and/or medium and/or high level of uncertainty as follows:

 

Drilling, sampling, and sample preparation and assay procedures: follow industry standards and best practices.

 

Reliability of sampling data: Acceptable database integrity and representativity based on SLR’s independent data verification and validation, as well as no significant bias observed in QA/QC analysis results. There are some areas with drill holes pre-2006 with limited data support, however, most of these zones are surrounding with drill holes with good data support.

 

Confidence in interpretation and modelling of geological and estimation domains: Mineralization domain solids show relatively acceptable agreement with the drill holes and underground mapping where the density of drill holes is less, particularly at the mineralization edges and areas supported by wider drill hole spacing is implied.

 

Geology and grade continuity: Based on drilling and underground mapping, trend analysis and variography, some domains show good geology and grade continuity, some other domains geometries are less well defined, and geological and grade continuity for these domains is less continuous and more variable.

 

Confidence in estimation of block grades for the main metals: Block grades correlate reasonably well with composite data, statistically and spatially, locally and globally.

 

Bulk density representativity: Reasonable for most of the domains. Density measurements for some domains are required.

 

Infill drilling: More drilling is required to determine continuity of mineralization in areas of wide drill spacing in order to upgrade Inferred Resources to Indicated.

 

Table 11-24:              Nexa Search Ellipse Ranges for Classification Criteria 

Nexa Resources S.A. – El Porvenir Mine

 

Classification Groups   Measured   Indicated   Inferred
Major Continuity Zones   25 m x 25 m x 12.5 m   50 m x 50 m x 25 m   100 m x 100 m x 50 m
Medium Continuity Zones   20 m x 20 m x 10 m   50 m x 50 m x 25 m   100 m x 100 m x 50 m
Minor Continuity Zones   15 m x 15 m x 10 m   40 m x 40 m x 20 m   60 m x 60 m x 30 m
Minimum DDH in ellipse1   3   3   2

 

Note:

 

1. Minimum DDH in ellipse refers to the isotropic search ellipsoid used to flag the distances in the blocks

 

Figure 11-19 show histogram validations of the classification based on the distance of each block to its closest sample for the major, medium, and minimum continuity domains, respectively. Figure 11-20 and Figure 11-21 show a plan view and a longitudinal section of the final model classification.

 

The SLR QP reviewed the classification results and is of the opinion that the resource classification criteria developed by El Porvenir are reasonable and acceptable, however, SLR noticed that there are a small number of areas where the largest continuity was assigned to small mineralization solids due to merging small wireframes for estimation purposes. This observation is not significant as there were few areas observed, however, SLR recommends re-evaluating the Measured and Indicated classification in these smaller solids. SLR also recommends monitoring the production data to confirm the drill spacing is appropriate for detailed planning.

 

 

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The SLR QP is of the opinion that the definitions for Mineral Resources used in this report have been classified in accordance with the definitions for Mineral Resources in S-K 1300, which are consistent with CIM (2014) definitions.

 

 

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Major Continuity Zones

 

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Medium Continuity Zones

 

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Minor Continuity Zones

 

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Figure 11-19:                   Histogram of Distance (M) by Category and Continuity Zone

 

 

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Figure 11-20: Final Classification Designation – Plan View

 

 

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Figure 11-21: Final Classification Designation – Longitudinal Section

 

 

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11.15 Block Model Validation

 

Nexa and SLR carried out a number of block model validation procedures including:

 

Visual inspection of composite versus block grades (Figure 11-22, Figure 11-23, Figure 11-24, and Figure 11-25).

 

Comparison between OK, ID3, NN, and composite mean grades (Table 11-25).

 

Swath plots (Figure 11-26).

 

Histogram comparison of grade block distribution versus composite grade distribution (Figure 11-27).

 

11.15.1 Visual Validation

 

A visual comparison on vertical sections and plan views found good overall correlations between the block and composite grades. Figure 11-22, Figure 11-23, Figure 11-24, and Figure 11-25 illustrate the visual correlation between the block and composite grades in the vcn3 and vcn32 mineralization domains on cross sections looking north for Zn, Pb, Cu, and Ag, respectively. There is a better correlation in the blocks closest to the composites as opposed to the blocks located further away, which show a reasonable degree of smoothing.

 

Nexa and SLR visually compared the composite and block grades on plans and sections and found that they correlated well spatially.

 

11.15.2 Global Statistical Comparison

 

The OK or ID3 block means for each mineralization domain were compared with the NN estimations. These comparisons produced percentage differences between the estimates which were within ±10% in most of the domains, with the exception of domains dl11, por9o, and por9q that appear to be underestimated and exiti1, porv9e, and por9cf1 that appear to be overestimated. Overall, the comparisons show that the methods used to estimate grades were appropriate. Table 11-25 shows an example of this comparison for the largest contributor domains for the Mineral Resource and the Mineral Reserve. SLR recommends reviewing the grade interpolation of these domains to control high grade smearing in low grade areas and vice versa. A grade domain will also help to prevent smearing.

 

Table 11-25: Comparison of ID3, OK, and NN Zinc Grades – Measured and Indicated Blocks 

Nexa Resources S.A. – El Porvenir Mine

 

                    ZN_NN     ZN_OK     Rel. diff     ZN_IDW3     Rel. diff  
          Inter.   #     Mean           Mean           in     Mean           in  
Domain   Class     Method   Blocks      (%)     CV      (%)     CV     Means      (%)     CV     Means  
de2     1     IDW3     35,886       2.53       1.53       2.69       1.02       -6 %     2.77       1.05       -9 %
de2     2     IDW3     42,173       2.41       1.11       2.32       0.64       4 %     2.44       0.77       -1 %
dl01     2     IDW3     30,088       2.43       0.85       2.30       0.41       6 %     2.29       0.53       6 %
dl05     2     IDW3     22,252       2.73       1.40       2.75       0.87       -1 %     2.66       0.97       3 %
dl11     2     IDW3     5,885       2.63       0.70       2.17       0.25       19 %     2.18       0.40       19 %
exiti1     2     IDW3     3,908       2.27       1.45       4.45       0.57       -65 %     3.24       0.81       -35 %

 

 

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                    ZN_NN     ZN_OK     Rel. diff     ZN_IDW3     Rel. diff  
          Inter.   #     Mean           Mean           i n     Mean           in  
Domain   Class     Method   Blocks     (%)     CV     (%)     CV     Means     (%)     CV     Means  
exito     1     IDW3     55,586       3.55       0.86       3.68       0.46       -3 %     3.66       0.56       -3 %
exito     2     IDW3     101,243       3.35       0.95       3.50       0.53       -4 %     3.40       0.66       -1 %
exitoa     1     IDW3     3,341       5.58       0.75       5.41       0.36       3 %     5.43       0.43       3 %
exitoa     2     IDW3     7,912       4.90       0.84       4.61       0.40       6 %     5.39       0.43       -10 %
exitob     1     IDW3     2,579       5.73       0.63       5.80       0.33       -1 %     5.88       0.39       -3 %
exitob     2     IDW3     13,377       5.06       0.75       5.34       0.37       -5 %     5.38       0.43       -6 %
porv9a     1     OK     13,820       6.61       0.92       6.56       0.54       1 %     6.83       0.57       -3 %
porv9a     2     OK     79,718       3.98       1.15       4.63       0.59       -15 %     4.43       0.71       -11 %
porv9e     1     IDW3     10,301       5.57       0.93       5.83       0.45       -5 %     5.79       0.45       -4 %
porv9e     2     IDW3     28,628       3.09       1.27       3.60       0.70       -15 %     3.69       0.74       -18 %
porv9w     1     IDW3     16,978       3.10       1.21       3.31       0.60       -7 %     3.36       0.68       -8 %
porv9w     2     IDW3     128,987       2.76       1.82       2.89       1.02       -5 %     2.80       1.26       -2 %
por9cf1     1     IDW3     1,790       5.70       1.16       5.70       0.61       0 %     5.87       0.80       -3 %
por9cf1     2     IDW3     10,145       4.35       1.23       5.11       0.60       -16 %     5.08       0.77       -16 %
por9o     1     IDW3     33,522       2.37       2.03       2.20       1.23       8 %     2.10       1.32       12 %
por9o     2     IDW3     94,951       2.82       1.35       3.08       0.94       -9 %     3.11       1.03       -10 %
por9p     1     IDW3     56,296       4.11       1.23       4.14       0.73       -1 %     4.15       0.77       -1 %
por9p     2     IDW3     88,538       4.25       1.16       4.30       0.67       -1 %     4.32       0.81       -2 %
por9q     1     IDW3     4,003       2.77       1.72       2.54       0.93       9 %     2.34       1.12       17 %
por9q     2     IDW3     113,741       4.97       1.13       5.00       0.58       -1 %     5.05       0.78       -2 %
por9r     1     IDW3     42,930       2.81       1.18       2.58       0.58       9 %     2.51       0.62       11 %
por9r     2     IDW3     34,198       3.87       0.89       2.54       0.51       42 %     2.65       0.57       37 %
por9s     2     IDW3     52,578       3.38       1.08       3.02       0.95       11 %     3.26       1.00       4 %
por9u     2     IDW3     15,549       2.08       1.09       2.10       0.49       -1 %     2.23       0.59       -7 %
sara1     2     IDW3     35,771       1.11       1.26       1.16       0.60       -5 %     1.12       0.80       -1 %
sara2     2     IDW3     39,877       1.51       1.27       1.37       0.86       9 %     1.41       0.99       7 %
sara3     2     IDW3     33,713       0.63       0.99       0.60       0.54       4 %     0.60       0.69       6 %
vcarmn     1     IDW3     6,721       6.99       1.06       6.97       0.75       0 %     7.12       0.76       -2 %
vcarmn     2     IDW3     68,807       8.05       1.06       7.75       0.71       4 %     7.62       0.82       5 %
vcn3w6     2     IDW3     14,019       3.74       0.72       3.16       0.40       17 %     3.38       0.53       10 %
vcn3w8     2     IDW3     21,119       4.24       1.38       4.38       0.63       -3 %     4.39       0.85       -4 %
vcn32     1     IDW3     2,479       4.77       0.90       4.71       0.57       1 %     4.89       0.64       -2 %

 

 

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                  ZN_NN     ZN_OK     Rel. diff     ZN_IDW3     Rel. diff  
          Inter.   #     Mean           Mean           in     Mean           in  
Domain   Class     Method   Blocks     (%)     CV     (%)     CV     Means     (%)     CV     Means  
vcn32     2     IDW3     77,285       6.74       0.79       6.75       0.40       0 %     6.86       0.53       -2 %
vc1b     1     IDW3     5,583       6.46       0.96       7.11       0.39       -10 %     7.03       0.47       -9 %
vc1b     2     IDW3     14,406       4.47       1.22       4.99       0.54       -11 %     4.59       0.70       -3 %
vc31     1     IDW3     103,152       4.63       1.12       4.56       0.71       1 %     4.52       0.78       2 %
vc31     2     IDW3     73,470       5.37       1.20       5.15       0.74       4 %     5.41       0.89       -1 %
vprg     1     IDW3     392,908       5.93       1.05       6.04       0.70       -2 %     6.06       0.74       -2 %
vprg     2     IDW3     476,484       3.25       1.44       3.44       1.01       -6 %     3.39       1.09       -4 %
v12ne     1     IDW3     44,661       4.20       1.20       4.09       0.56       3 %     4.12       0.77       2 %
v12ne     2     IDW3     31,050       4.78       1.23       4.28       0.59       11 %     4.41       0.77       8 %
v12s33     1     IDW3     20,983       2.62       1.10       2.62       0.66       0 %     2.53       0.72       4 %
v12s33     2     IDW3     11,721       5.18       0.84       4.99       0.60       4 %     5.39       0.69       -4 %
v5i     1     OK     75,980       7.48       0.85       7.45       0.42       0 %     7.46       0.47       0 %
v5i     2     OK     71,267       3.28       1.36       3.61       0.76       -10 %     3.46       0.88       -5 %
v5ne5     2     IDW3     11,036       2.74       0.81       2.88       0.49       -5 %     2.86       0.58       -4 %

 

In the SLR QP’s opinion, the statistical tables that compare the declustered composite mean (NN) and block zinc grades show that the two populations have similar distributions with not much grade smoothing evident.

 

11.15.3 Local Validation

 

Swath plots were generated to assess for local bias and to compare the differences between the OK and ID3 block grade estimates and the NN estimated grades for each domain and element. The plots in Figure 11-26 show the combined Measured, Indicated, and Inferred blocks in the east, north, and vertical directions. SLR considers that the results show acceptable agreement of composite (NN) and block grades.

 

Histograms comparing the composite grades versus the block grades suggest that the grade distribution of these two data are similar. An example is shown in Figure 11-27.

 

On the basis of its review and validation procedures, the SLR QP is of the opinion that the grade estimates for zinc, copper, lead, and silver are reasonable, and that the block model is suitable to support Mineral Resource and Mineral Reserve estimation.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Figure 11-22: Vertical Section Showing Zn Blocks Versus Composite Grades

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Figure 11-23: Vertical Section Showing Pb Blocks Versus Composite Grades

 

 

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Figure 11-24: Vertical Section Showing Ag Blocks Versus Composite Grades 

 

 

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Figure 11-25: Vertical Section Showing Cu Blocks Versus Composite Grades 

 

 

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Figure 11-26: Swath Plot: Zn Grade Variation Along X, Y, and Z

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Figure 11-27: Zn OK, ID3, Nn Blocks Versus Zn Composite Histograms

 

11.16 Mineral Resource Reporting

 

The Mineral Resources for the El Porvenir underground operation as of December 31, 2020, are summarized in Table 11-1. The Mineral Resource estimate was reported using all the material within resource shapes generated in Deswik software, satisfying minimum mining size, continuity criteria, and using NSR cut-off values of US$60.06/t for the Upper Zone, US$61.09/t for the Intermediate Zone, US$59.75/t for the Lower Zone, and US$63.37/t for the Mine Deepening Zone for C&F resource shapes (Figure 11-28 and Figure 11-29). NSR cut-off values for the Mineral Resources were established using a zinc price of US$2,869.14/t Zn, a lead price of US$2,249.40/t Pb, a copper price of US$7,427.59/t Cu, and a silver price of US$19.38/oz Ag. El Porvenir Mineral Resources are in compliance with the S-K 1300 resource definition requirement of “reasonable prospects for economic extraction”.

 

Wireframe models for the underground excavations as of September 30, 2020 were prepared to remove the portions of the mineralized zones that had been mined-out before the resource and reserve stopes were generated. Mineral Resource and Mineral Reserves estimates were depleted for forecast production from October 1, 2020 to December 31, 2020. After year end, SLR verified the estimate by reviewing actual mining results for this short period of projected mining. Deviations from plan were approximately 1% less of total Mineral Reserves tonnage. The SLR QP is of the opinion that this has had an insignificant impact on the year end resource and reserve estimates. The sub-blocking functions of the Deswik software package were employed to maximize the accuracy of the mined-out contacts. For the underground excavations, solid models of the stopes, mine development, and drifts were constructed digitally from data collected using a total station surveying unit.

 

 

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Nexa also generated solids for non-recoverable areas (“constraint” solids) due to poor ground conditions and inaccessibility, to remove these zones from the Mineral Resources and Mineral Reserves. SLR considers generating operational and safety constraints to identify, quantify, and remove the tonnes and grades from Mineral Resources and Mineral Reserves to be a good practice. SLR recommends documenting all the data support to define non-recoverable solids and document any changes to these solids.

 

The SLR QP reviewed the resource shapes and is of the opinion that overall they are reasonable, however, there are few areas where shapes do not follow the mineralization trend wireframe and, as a result, unnecessary internal dilution was incorporated and some resources were excluded locally. SLR recommends adjusting these resource shapes to follow mineralization trend.

 

SLR also noticed that there is a significant amount of tonnes within blocks above the NSR cut-off value that were not included in the Mineral Resources or Mineral Reserves, and are not part of the “constraint” solids. Nexa and SLR reviewed these areas and note that they are mostly skin remnants, however, SLR recommends re-evaluating these zones on an ongoing basis to potentially include part of these tonnes with continuous blocks that have the potential to be recoverable, to generate resource shapes and possibly reserve stopes.

 

SLR also observed a minor overlapping of the resource shapes with areas that were within the “constraint solids”, and few reserve stopes that were overlapping with mined-out solids. The overlapping volume is not material as it is less than 1%. Nevertheless, the SLR QP recommends improving and cleaning up the mined-out solids to deplete appropriately the block model and resource and reserve shapes, and incorporating a validation step of reviewing for overlapping of solids.

 

In the SLR QP’s opinion, the assumptions, parameters, and methodology used for the El Porvenir underground Mineral Resource estimates are appropriate for the style of mineralization and mining methods.

 

The SLR QP is of the opinion that with consideration of the recommendations summarized in Section 1 and Section 23, any issues relating to all relevant technical and economic factors likely to influence the prospect of economic extraction can be resolved with further work.

 

 

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Figure 11-28: Plan View of Mineral Resources Inclusive and Exclusive of Mineral Reserves

 

 

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Figure 11-29: Longitudinal Section of Mineral Resources Inclusive and Exclusive of Mineral Reserves

 

 

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11.17 Comparison to Previous Mineral Resource Estimates

 

A comparison of the current Nexa Mineral Resource estimate, exclusive of Mineral Reserves, to the previous 2019 Mineral Resource estimate is presented in Table 11-26. Overall, the resources have slightly decreased. The differences are primarily due to the following changes:

 

Higher NSR cut-off values.

 

Decrease in tonnes in Porvenir 9, Progreso, Veta 1204 due to changes in interpretation, and in Carmen Norte 3, Carmen Norte 4, Veta 1204 inferior, and Socorro due to new drilling and reinterpretation. Some of the decrease in tonnes was offset by delineating new resources in Sara, and incorporating more resources in Don Lucho, AM, Integration ATA EP, Carmen 1, and Exito.

 

Depletion of material through mining.

 

Incorporation of “constraint ” solids or non-recoverable areas that are excluded from the Mineral Reserves and Mineral Resources, due to poor ground conditions and inaccessibility.

 

Increase in silver values due to higher capping values.

 

Slightly lower density values due to the addition of 219 density determinations from the 2019-2020 drilling campaign located mostly at Sara, Don Lucho, Integration ATA EP, Veta Carmen Norte 3, and Veta AM.

 

 

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Table 11-26: EL Porvenir Underground Comparison of 2020 versus 2019 Mineral Resources 

Nexa Resources S.A. – El Porvenir Mine

 

    El Porvenir Mineral Resources - December 31, 2020   El Porvenir Mineral Resources - December 31, 2019
        Grade   Contained Metal       Grade   Contained Metal
Category   Tonnage   Zinc   Lead   Copper   Silver   Zinc   Lead   Copper   Silver   Tonnage   Zinc   Lead   Copper   Silver   Zinc   Lead   Copper   Silver
    (Mt)   %   %   %   g/t   (000 t)   (000 t)   (000 t)   (000 oz)   (Mt)   %   %   %   g/t   (000 t)   (000 t)   (000 t)   (000 oz)
Measured   0.23   2.59   0.99   0.23   63.46   6.0   2.3   0.5   471   1.04   3.10   1.08   0.21   70.20   32.2   11.2   2.2   2,346
Indicated   1.33   2.93   0.89   0.20   63.33   39.0   11.9   2.6   2,715   1.25   3.24   1.01   0.21   57.80   40.5   12.6   2.6   2,321
M+I   1.56   2.87   0.91   0.20   63.35   45.0   14.2   3.2   3,186   2.29   3.17   1.04   0.21   63.40   72.7   23.8   4.8   4,667
Inferred   8.47   3.60   0.95   0.23   78.37   305.0   80.8   19.8   21,345   9.31   3.62   0.85   0.22   58.00   337   79.1   20.5   17,361

 

 

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12.0 Mineral Reserve Estimates

 

12.1 Summary

 

El Porvenir is an underground mine that, at full output, produces approximately 5,600 tpd of ore. The Mine has been in operation since 1949. The current Mineral Resource and Mineral Reserve model consists of 430 deposits of various sizes and dips.

 

The Mineral Reserves are grouped into four mining zones, which are differentiated by elevation (Table 12-1).

 

Table 12-1: El Porvenir Mining Zones 

Nexa Resources S.A. – El Porvenir Mine

 

Original Name   Term Used in Report   Definition
Zona Alta   Upper Zone   Above 3,700 m
Zona Intermedia   Intermediate Zone   Between 3,100 m and 3,700 m
Zona Baja   Lower Zone   Between 2,900 m and 3,100 m
Profundizacion   Mine Deepening Zone   Below 2,900 m

 

The Upper Zone is the oldest mining area, where most of the mineralized areas have been mined, with currently available stopes mainly corresponding to the recovery of remnant material and new mineralized zones. The vertical spacing of levels in the Upper Zone ranges between 60 m and 100 m.

 

The Intermediate and Lower zones are the major current mining areas with levels spacing of approximately 200 m.

 

The Mine Deepening Zone is the future mining area at depth and has a level spacing of 100 m.

 

El Porvenir uses two mining methods, C&F and SLS. C&F uses the overhand method to extract the ore using attack ramps and is employed in areas of poor ground conditions that do not allow for the SLS method to be used. The SLS method is used in areas that have favourable ground conditions and are steeply dipping.

 

Measured and Indicated Mineral Resources were used as inputs for conversion into Proven and Probable Mineral Reserves, respectively, and for the mine design process.

 

Mineral Reserves were estimated by flagging mined-out stope surveys through September 2020 and planned mining to December 31, 2020, as zero-values in the block model. After year end, SLR verified the estimate by reviewing actual mining results for the short period of projected mining. Deviations from the plan, amounting to approximately 1% of total Mineral Reserves tonnage, were caused by 2020 infill drilling and mining of some areas classified as Inferred at the time of the estimate. SLR considers these deviations to be typical of ongoing mining operations, and not significant or material to the estimate of Mineral Reserves.

 

The Mineral Reserves for El Porvenir as of December 31, 2020 are summarized in Table 12-2.

 

 

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Table 12-2: Mineral Reserves – December 31, 2020 

Nexa Resources S.A. – El Porvenir Mine

 

        Grade   Contained Metal
Category   Tonnage
(000 t)
  (% Zn)   (% Pb)   (% Cu)   (g/t Ag)   (000 t Zn)   (000 t Pb)   (000 t Cu)   (000 oz Ag)
Proven   3,764   3.76   0.98   0.25   62.9   141.3   36.9   9.5   7,602
Probable   10,086   3.74   0.85   0.22   62.8   377.6   85.5   22.4   20,364
Total   13,850   3.75   0.88   0.23   62.8   518.9   122.4   31.9   27,966

 

Notes:

 

1. The definitions for Mineral Reserves in S-K 1300 were followed for Mineral Reserves which are consistent with CIM (2014) definitions.

2. Mineral Reserves are reported on a 100% ownership basis. Nexa owns an 80.16% interest.

3. Mineral Reserves are estimated at cut-off grades depending on the zone and mining method.

4. Mineral Reserves are estimated using average long term prices of Zn: US$2,494.90/t (US$1.13/lb); Pb: US$1,956.00/t (US$0.89/lb); Cu: US$6,457.90/t (US$2.93/lb); Ag: US$16.85/oz.

5. A minimum mining width of 5 m was used.

6. Density is 3.12 t/m3.

7. Numbers may not add due to rounding

 

The SLR QP is not aware of any risk factors associated with, or changes to, any aspect of the modifying factors such as mining, metallurgical, infrastructure, permitting, or other relevant factors that could materially affect the Mineral Reserve estimate.

 

12.2 Dilution

 

The following formula is used to determine the amount of dilution in a stope:

 

Dilution (%) =   mass of waste
mass of ore + mass of waste

  

The dilution used in the Mineral Reserve estimation is implemented through two means:

 

Dilution by design (internal dilution)

 

Dilution by overbreak (planned/operational dilution)

 

Dilution by design refers to the waste incorporated during the stope design process, in which portions of waste wall rock (non categorized) and Inferred blocks are incorporated inside the shape of the stopes. This is commonly referred to as internal dilution and is shown inside the blue stope design in Figure 12-1.

 

Dilution by overbreak is determined from several factors such as:

 

Geometry of the mineralized zone

 

Mining method

 

Operational conditions

 

Geomechanics

 

Rock mechanics implemented

 

Presence of water

 

These factors determine the amount of planned overbreak in a stope.

 

 

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The dilution factor for C&F is 0.5 m of dilution applied to the hanging wall and footwall of the design. The dilution was applied using DSO.

 

The dilution factor for SLS stopes is 10% and is applied post design as a factor. Nexa is in the process of determining the dilution factor for each mining method and is using the above factors as an acceptable base point. The SLS stopes are in good ground and have an average dip of 80°. In the SLR QP’s opinion, the factor used is reasonable.

 

 

 

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Figure 12-1: Schematic Section View of Stope Illustrating Dilution and Extraction Values in a Stope

 

 

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12.3 Net Smelter Return

 

A NSR value calculation was performed on potential mining blocks, considering the following attributes:

 

Grades: Zn, Pb, Cu, Ag

 

Metal prices

 

Metallurgical recovery

 

Commercial terms and conditions

 

The NSR value is expressed as US$/t and is calculated for Mineral Reserves to make an adequate comparison with production costs in order to determine whether mined material is ore (economically minable) or waste.

 

The sellable products from the Mine are:

 

Zinc concentrate

 

Lead concentrate with silver content

 

Copper concentrate with silver content

 

The payable metals in concentrates include the applicable concentrate treatment, transportation, refining charges, deductions, and penalty elements, according to sales agreements signed between mines and smelters or traders.

 

Costs and other parameters used to calculate the NSR cut-off value are shown in Table 12-3. The metal prices are based on 10 year average of the LME projected prices.

 

The average NSR factors are calculated using the LOM revenue contribution from each metal net of off-site costs and factors, divided by the reserve grade for that metal, and are indicative of the relative contribution of each metal unit to the economics of the mine. For most metals, a variable recovery (as a function of head grade) was used, and therefore the average NSR factors should not be applied to head grades without considering the head grade versus recovery relationship.  Therefore, the NSR factors are variable by head grade.  The grade-recovery relationship for each metal based on recent operating performance are presented in Figure 12-2, Figure 12-3, and Figure 12-4.

 

Table 12-3: NSR Data 

Nexa Resources S.A. – El Porvenir Mine

 

Item   Units    
         
Net Metallurgical Recovery *
Zn   %   89.60
Pb   %   79.21
Cu   %   14.29
Ag   %   62.90
Cu Concentrate Payable %        
Cu   %   96.7
Ag   %   90
Pb Concentrate Payable %        
Pb   %   95
Ag   %   95

 

 

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Item   Units      
Zn Concentrate Payable %            
Zn   %     94.6  
Ag   %     70  
Metal Prices            
Zn   US$/lb     1.13  
Pb   US$/lb     0.89  
Cu   US$/lb     2.93  
Ag   US$/oz     16.85  
Logistics and TC            
Zn Concentrate   US$/t conc   $ 295  
Pb Concentrate   US$/t conc   $ 266  
Cu Concentrate **   US$/t conc   $ 279  
Integrated Zn            
Conversion Cost   US$/t Zn prod   $ 452  
Premium   US$/t Zn prod   $ 173  
Refining Cost            
Ag in Pb conc   US$/oz   $ 1.00  
Ag in Cu conc   US$/oz   $ 0.50  

 

* Based on LOM average metal grades
** Included a US$16.68/t penalty

 

Nexa reviewed supply and demand projections for zinc, lead, and copper, as well as consensus long term (ten year) metal price forecasts. SLR verified that Nexa’s selected metal prices for estimating Mineral Reserves are in line with independent forecasts from banks and other lenders.

 

Metallurgical recoveries used for Mineral Reserves are based on historical data which has been consolidated by Nexa in Ore Head Grade vs. Recovery Curves presented in Figure 12-2, Figure 12-3, and Figure 12-4. These curves are developed by regression of historical performance data sets.

 

 

 

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Figure 12-2:             Zinc Recovery Curve

 

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Figure 12-3:            Lead Recovery Curve

 

 

 

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Figure 12-4:                Copper Recovery Curve

 

 

12.4 Cut-Off Grade

 

Metal prices used for Mineral Reserves are based on consensus, long term forecasts from banks, financial institutions, and other sources. For Mineral Resources, metal prices used are slightly higher than those for Mineral Reserves.

 

Several cut-off NSR values (or cut-off grades) have been calculated for El Porvenir dependent on the mining zone and mining method. Each zone is based on an elevation range as listed in Table 12-1. Each zone has a different material movement cost depending on whether truck haulage, shaft, or a combination of the two is used. The Lower Zone, for instance, has a lower cut-off grade than the other zones due to heavy skipping influence as shown in Table 12-4, below. Economic cut-off grade included direct and indirect costs as follows:

 

Mining costs (including cost of mine development costs)

 

Processing costs

 

G&A costs

 

Measured or Indicated blocks that have an average NSR value above the economic cut-off grade, are scheduled to be mined, and are not isolated (i.e., a single stope far from other stopes) are classified as economically mineable and included in the Mineral Reserve estimate.

 

Marginal mining blocks are defined as blocks below the economic cut-off grade, which, however, benefit from certain conditions such as location and thus can be evaluated using a marginal cut-off grade. The stopes generally have development complete due to development accessing adjacent stopes and therefore, the development costs are removed for such marginal blocks resulting in the marginal cut-off grade.

 

Capital costs have been averaged in cut-off grade calculation.

 

 

 

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Mining blocks with an NSR value below the marginal cut-off grade are classified as waste.

 

Table 12-4:        Cut-Off Grade Calculation by Mining Zone and Method 

Nexa Resources S.A. – El Porvenir Mine

 

Item   Units   SLS Costs   C&F Cost
Upper Zone            
Mine Cost   US$/t   38.95   42.26
Development   US$/t   13.82   13.82
Plant Costs   US$/t   10.50   10.50
G&A   US$/t   7.30   7.30
Cut-Off Grade   US$/t   56.75   60.06
Marginal Cut-Off Grade   US$/t   42.93   46.24
             
Development Cost   US$/m   1,395.73   1,395.73
             
Intermediate Zone            
Mine Cost   US$/t   39.98   43.29
Development   US$/t   13.82   13.82
Plant Costs   US$/t   10.50   10.50
G&A   US$/t   7.30   7.30
Cut-Off Grade   US$/t   57.78   61.09
Marginal Cut-Off Grade   US$/t   43.96   47.27
             
Development Cost   US$/m   1,395.73   1,395.73
             
Lower Zone            
Mine Cost   US$/t   38.64   41.95
Development   US$/t   13.82   13.82
Plant Costs   US$/t   10.50   10.50
G&A   US$/t   7.30   7.30
Cut-Off Grade   US$/t   56.44   59.75
Marginal Cut-Off Grade   US$/t   42.62   45.93
             
Development Cost   US$/m   1,395.73   1,395.73
             
Mine Deepening Zone            
Mine Cost   US$/t   42.26   45.57
Development   US$/t   13.82   13.82
Plant Costs   US$/t   10.50   10.50
G&A   US$/t   7.30   7.30

 

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Item   Units   SLS Costs   C&F Cost
Cut-Off Grade   US$/t   60.06   63.37
Marginal Cut-Off Grade   US$/t   46.24   49.55
             
Development Cost   US$/m   1,395.73   1,395.73

 

SLR considers that the operating costs are reasonable for this type of operation and mining methods. 

 

 

 

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13.0 Mining Methods

 

13.1 Introduction

 

El Porvenir is one of the deepest underground mines in South America, extending more than 1,800 m below the main access level. El Porvenir produces approximately 2.1 Mtpa of zinc-lead-copper ore using two mining methods, with the predominant method being mechanized overhand C&F. C&F has been used at El Porvenir for many decades and accounts for over 80% of its production. The remainder of the output comes from SLS, which was introduced at the operation in 2018. El Porvenir uses a version of this method called Avoca, also referred to as longitudinal longhole retreat mining.

 

Mine production is presently underway in the Upper Zone, the Intermediate Zone, the Lower North Zone, and the Lower West (El Porvenir 9) Zone (Figure 13-1). Table 13-1 indicates the mining methods used in the active mineral deposits within these zones.

 

Table 13-1:         Mining Methods in Active Mining Zones 

Nexa Resources S.A. - El Porvenir Mine

 

    C&F   SLS
Upper Mine Zone        
DE2      
V1204      
CN4      
AM      
Don Lucho      
         
Intermediate Mine Zone        
CN3      
Exito      
Carmen    
         
Lower North Mine Zone        
CN3      
         
Lower West Mine Zone        
Porvenir-9      

 

 

 

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Technical Report Summary - January 15, 2021 

 

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Figure 13-1:             Active Mining Zones

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13.2 Mine Design and Mining Methods

 

Table 13-2 through Table 13-5 present the design parameters used for modelling Mineral Reserves. Respectively, these tables provide the parameters for stope design, development excavations, production rates, dilution, and recovery.

 

Table 13-2:          Long Term Stope Design Parameters 

Nexa Resources S.A. - El Porvenir Mine 

 

Item   Method   Parameters
(m)
Height   C&F   5.00
  SLS   20.00
Minimum Width   C&F   5.00
  SLS   5.00
Maximum Width   C&F   10.00
  SLS   8.00
Length   C&F   5.00
  SLS   10.00
Minimum Pillar - Veins   C&F   5.00
  SLS   5.00
Rib Pillar   C&F   -
  SLS   10.00
Sill Pillar - Panels   Above Level -440   10.00
  Below Level -440   15.00
Pillar - Surface   Upper Zone   30.00

 

Table 13-3:          Development Design Parameters 

Nexa Resources S.A. - El Porvenir Mine

 

Item   Width
(m)
  Height
(m)
  Grade
(%)
  Radius
(m)
Ramps for Truck Haulage   4.50   4.00   13%   18.00
Ramps for Load-Haul- Dump Units (LHDs)   4.50   4.00   13%   18.00
Main Crosscut   4.50   4.00   + 1%   8.00
Crosscut between Veins   4.50   4.00   + 1%   8.00
Bypass   4.50   4.00   Per design   8.00
Access to Orebody   4.50   4.00   15%   8.00

 

 

 

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Item   Width
(m)
  Height
(m)
  Grade
(%)
  Radius
(m)
Attack Ramps   Per design   Per design   Per design   8.00
Drift   4.50   4.00   + 1%   8.00
Ventilation Drift   4.00   4.00   + 1%   8.00
Electrical Substation   4.00   4.00   + 1%   6.00
Sump   4.50   4.00   -15%   6.00
Diamond Drill Station   6.00   6.00   + 1%   6.00
Raise Bore (diameter)   2.1/3.1   2.1/3.1   -   -
Raise (diameter)   2.1/3.1   2.1/3.1   -   -

  

Table 13-4:            Long Term Production Rate Parameters 

Nexa Resources S.A. - El Porvenir Mine

 

Item   Units   Parameters
C&F Crew Contribution - ZA   t/month   35,000
C&F Crew Contribution - ZI/ZB   t/month   38,000
SLS Contribution   t/month   17,500
Hydraulic Backfill   t/month   10,500
Advance per Crew   blasts/month   55
Output through Hoisting   t/month   133,000
Output through Truck Haulage   t/month   46,000
Ore Density   t/month   3.54
Waste Density   t/month   2.98

 

Table 13-5:           Long Term Parameters For Dilution And Recovery 

Nexa Resources S.A. - El Porvenir Mine 

 

Item   Method   Units   Parameters
Operational Dilution   C&F   (m)   1.00
    SLS   (%)   10.00
Planned Dilution   C&F   (m)   Varies
    SLS   (%)   Varies
Recovery   C&F   (%)   98.00
    SLS   (%)   85.00

 

 

 

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Table 13-6 and Table 13-7 provide monthly results for mine production and development advance during recent years. El Porvenir mined 2.11 Mt of ore in 2019 and 1.52 Mt in 2020, and advanced development headings by 12.2 km in 2019 and by 10.8 km in 2020. Dilution accounted for 37.5% of the ore tonnage produced in 2020.

 

Table 13-6:             Mine Production -- Years 2018 to 2020 

Nexa Resources S.A. - El Porvenir Mine

 

    Units   Jan   Feb   Mar   Apr   May   June   July   Aug   Sept   Oct   Nov   Dec   Total
2018                                                        
Ore Mined   000 t   172.8   175.7   171.4   174.6   184.8   179.2   181.3   179.2   176.1   186.1   177.7   186.0   2,145.0
Stockpile   000 t   7.4   22.4   9.9   9.2   14.0   11.5   9.5   12.8   3.1   18.1   11.3   10.8   11.7
Dilution   %   23.1   16.3   16.2   22.8   20.9   21.5   22.1   24.6   22.0   22.0   22.0   36.8   22.6
                                                         
2019                                                        
Ore Mined   000 t   179.8   170.2   187.9   172.9   191.4   165.4   193.5   169.8   179.3   148.8   186.4   165.4   2,110.7
Stockpile   000 t   16.6   20.0   17.7   14.9   13.1   6.8   9.1   5.7   2.3   2.7   2.0   0.4   9.3
Dilution   %   34.0   25.3   33.4   41.9   35.9   39.6   35.5   38.8   31.8   34.1   29.0   27.4   33.9
                                                         
2020                                                        
Ore Mined   000 t   163.7   150.5   102.6   -   80.2   151.7   116.6   145.6   165.0   139.1   139.6   170.2   1,524.7
Stockpile   000 t   11.7   0.62   -   -   8.76   6.3   1.2   0.41   0.54   0.90   1.6   0.13   3.2
Dilution   %   36.5   36.5   31.6   -   29.1   38.4   35.4   44.2   45.0   35.3   37.0   36.0   37.5

 

Table 13-7:          Development Advance - Years 2017 to 2020 

Nexa Resources S.A. - El Porvenir Mine

 

Year   Units   Jan   Feb   Mar   Apr   May   June   July   Aug   Sept   Oct   Nov   Dec   Total
2017   m   1,427   1,111   847   1,039   1,085   1,128   1,095   963   974   1,065   1,156   873   12,762
2018   m   1,545   986   1,153   1,363   1,180   1,215   1,175   1,213   1,245   1,249   1,214   916   14,453
2019   m   1,135   1,235   1,138   955   763   977   1,120   1,021   983   976   999   939   12,242
2020   m   1,139   967   690   -   264   1,020   612   892   1,254   1,333   1,403   1,239   10.811

 

C&F and SLS have similar development requirements as they both involve dividing a mining zone into horizons between sublevels and excavating the ore in an ascending fashion. Sublevels are typically spaced at 20 m vertical intervals and accessed via spiral ramps. The development on each sublevel includes an access drift, a footwall drive, and crosscuts or attack ramps, which provide access to the orebody. For SLS, the footwall drive can be as close as 15 m from the footwall contact, whereas for C&F, they have to be offset from it by 60 m to provide sufficient distance for fanning the attack ramps. Figure 13-2 illustrates a zone mined with C&F, while Figure 13-3 shows a zone with SLS. 

 

 

 

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Figure 13-4 illustrates C&F’s mining cycle, consisting of drilling, blasting, mucking, and ground support. Backfilling is carried out after completing a cut and before initiating the next higher-up one. Table 13-8 provides information about the method as applied at the Mine. With C&F, ore in an ore block is mined from bottom to top in five metre thick horizontal slices or cuts. The first cut of the stope is mined as a drift through the orebody, which is slashed out between the footwall and hanging wall contacts. The subsequent cuts are mined by breasting, which involves slashing the ore by drilling horizontal holes with the jumbo and blasting the ore downwards to the previous cut’s free face. Following each breast, the broken ore is mucked and transported out of the stope with an LHD.

 

Table 13-8:            Cut and Fill Mining Method at El Porvenir 

Nexa Resources S.A. - El Porvenir Mine

 

Parameter   Description
Version   Mechanized overhand C&F
Sublevel interval   Typically, 20 m
Cut height   5 m
Cuts accessed per attack ramp   4 cuts
Attack-ramp grade   15%
Excavation method   Breasting - horizontal drilling with jumbo
Explosive   Ammonium nitrate/fuel oil (ANFO)
Backfill   • Up to 70% uncemented rockfill and
  • remainder hydraulic tailings backfill

 

 

 

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Figure 13-2:                Cut and Fill Stoping – Longitudinal View 

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Figure 13-3:            Sublevel Stoping – Longitudinal View 

 

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Figure 13-4:             Cut and Fill Mining Cycle 

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Attack ramps driven from the sublevels provide access to a C&F stope. Figure 13-5 illustrates the procedure for accessing the progressively higher cuts. An attack ramp is initially driven with a -15% inclination to access a cut below the sublevel’s elevation. The attack ramp is then back-slashed in a fan-like fashion with some muck left on the floor to access each subsequent cut. The ramp to the highest cut will have a continuous positive grade over its entire 60 m length. The next cut must be accessed with a new attack ramp, driven at -15% from the next higher-up sublevel. An attack ramp at El Porvenir permits accessing four cuts from a sublevel.

 

After mining the complete cut or horizontal slice of a C&F stope, the open space must be backfilled from floor to back. Besides supporting the stope walls, the backfill provides the floor for mining the next higher-up cut. Hydraulic backfill is the principal backfill used for C&F at the Mine and consists of classified mill tailings sent underground via a pipeline as slurry. Up to 70% of the stope is filled with rockfill, which is waste from development headings. This material is dumped on the stope floor, after which hydraulic backfill is placed to tight-fill the remaining opening. The stope then sits inactive for several days until the water drains out of the hydraulic backfill, leaving it with a consistency similar to fine sand.

 

 

 

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Figure 13-5:             Access to Cut and Fill Stopes 

 

 

 

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While C&F is the predominant mining method at El Porvenir, SLS accounts for a small but growing proportion of the production. The Mine uses a version of SLS called Avoca, which is used instead of C&F when the configuration of the orebody and the ground conditions are suitable for the method and when development waste is available for backfilling. Table 13-9 analyzes the advantages and disadvantages of the SLS Avoca method as compared with C&F.

 

Table 13-9: Advantages and Disadvantages of Avoca Compared with Cut and Fill 

Nexa Resources S.A. - El Porvenir Mine

 

Advantages   Disadvantages

•      Is an excellent method for disposing of development waste, which is not the case with C&F.

 

•      Has a higher productivity and lower mining costs than C&F.

 

•      Backfilling can be carried out in parallel with longhole drilling.

 

•      Sublevel development may be less. The footwall drive can be located closer to the contact which reduces the length of crosscuts and there is no back-slashing of attack ramps.

 

•      Less ground support is required as the stoping procedure does not involve breasting cuts or back-slashing attack ramps. 

 

•      Is not a selective method like C&F, so wall dilution will be higher and recovery lower.

 

•      Additional dilution will occur when backfill from the waste pile is mucked with the ore.

 

•      The method only works with rockfill. It is not compatible with hydraulic backfill.

 

•      Is only suitable if the footwall dips at a sufficiently steep angle such that the broken ore can be drawn down by gravity without it hanging up on the footwall.

 

•      Is less suitable for mining zones with poor ground conditions than C&F. For instance, cable bolts may be required to stabilize a weak hanging wall. 

 

As previously stated, the SLS Avoca method is similar to C&F in terms of its bottom-up mining sequence and development requirements. The main difference between the methods is how they excavate the ore horizons between sublevels. C&F mines the ore in horizontal slices by breasting, while Avoca mines vertical slices by benching.

 

Avoca benches the ore in a retreating fashion. The benches retreat towards the middle of the vein, starting from the opposite ends of the vein. The ore between two sublevels is completely mined-out once the final bench is blasted at the middle of the vein. Backfilling is an integral part of the mining cycle. The stope is progressively backfilled as the ore is extracted. The rockfill pile advances behind the bench. Figure 13-6 illustrates the Avoca version of SLS, and Figure 13-7 shows the method’s mining cycle. Table 13-10 provides information about how Avoca is applied at El Porvenir.

 

 

 

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Source: Nexa

 

Figure 13-6:                Avoca Mining Method

 

 

 

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Figure 13-7:              Sublevel Stoping Mining Cycle 

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Table 13-10:             Sublevel Stoping Method at El Porvenir 

Nexa Resources S.A. - El Porvenir Mine

 

Parameter   Description
SLS at El Porvenir    
• Contribution   15% to 20% of mine production
• Version of SLS   Avoca (longitudinal longhole retreat mining)
     
Orebody Characteristics Required for SLS    
• Vein Configuration   Continuity, tabular form, regular profile
• Dip   Dip > 65°
• Width   Width > 3 m
• Ground Conditions   RMR > 40 (favourable ground)
     
Longhole Drilling    
• Drilling Direction   Downholes
• Hole Diameter   63 mm
• Burden   1.5 m
• Spacing   1.5 m
• Drilling Layout   Parallel or fanned depending on vein geometry
• Bench-Face Inclination   90° - holes in each row are drilled in vertical plane
• Bench Height   15 m to 18 m, depending on sublevel interval
     
Production Blasting    
• Typical Blast   Three rows of longholes per blast
• Explosive   ANFO
• Primer   One stick of emulsion per hole
• Controlled Blasting   Sometimes emulsion in footwall and hanging wall
• Slot to Initiate Bench   Vertical crater retreat (VCR) drop raise between upper and lower ore drives
     
Backfilling    
• Backfill   Loose rockfill from development waste
• Backfilling Procedure   LHD enters from extreme ends of stope
• Minimum Span   20 m to 25 m rockfill pile to ore bench before blast
• Maximum Span   30 m to 40 m rockfill pile to ore bench after blast
• Backfill Pile Slope   Angle of repose = 30° to 40°
     
Ground Support    
• Cable Bolting   In hanging wall with shallow dip or poor ground.
• Cable Bolts   Up to 15 m long, depends on stope design.
• Shotcrete   50 mm, on sublevels per geotechnical recommendation
Crosscut Spacing   80 m to 120 m

 

 

 

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Benching at each end of the vein is initiated by drilling and blasting longholes into a slot raise consisting of a drop raise between the upper and lower ore drives. The benches are drilled with rows of longholes, which are drilled as downholes from the upper ore drive. Typically, three rows of longholes are blasted at a time. Figure 13-8 is an example of a drilling layout for a row of longholes in an Avoca stope.

 

Following each bench blast, an LHD mucks the broken ore from the lower sublevel ore drive. As the LHD operates beyond the bench’s brow, some of the ore must be mucked using radio remote control. The LHD transports each bucket of ore out of the stope, and either dumps it into an orepass on the sublevel or loads it onto a truck.

 

With Avoca, backfilling is an integral part of the mining cycle, generally proceeding in parallel with production drilling. Once the blasted ore is mucked out, the stope is backfilled by advancing the pile of rockfill toward the bench, filling the void created by mining it.

 

An LHD delivers each bucket of rockfill to the stope entering via one of the upper sublevel crosscuts. It travels over the rockfill already deposited and dumps its load over the edge of the advancing pile. The filling operation stops when the gap between the top edge of the waste pile and the bench edge measures 20 m to 30 m. This gap provides a free face for the next production blast. When blasted, the broken ore impacts against the sloping waste pile, rather than scattering about an open stope. When mucking the ore, the LHD operator must avoid mixing it with the waste backfill.

 

In veins with strike lengths of less than approximately 100 m, El Porvenir may use a version of the mining method called Modified Avoca. With this version, the LHD delivers rockfill to the stope via the central crosscut rather than the ones at the ends of the vein. The LHD travels through the upper sublevel ore drive and dumps the rockfill starting from the bench edge.

 

The advantage of Modified Avoca is that a footwall drive is not required. Its disadvantages are:

 

Production drilling cannot be carried out in parallel with backfilling on the same side of the stope.

 

Ventilation uses vent ducting.

 

Extra rockfill handling is required.

 

This additional handling occurs as some of the rockfill must be mucked out from the lower ore drive to open up a free face for blasting the next bench. The time and cost saved by eliminating the footwall drive often outweigh the disadvantages. Modified Avoca is not a suitable method when the vein’s strike length exceeds 100 m as the LHD’s in-stope travel time becomes excessive.

 

El Porvenir has successfully applied C&F mining for decades, and C&F will continue to be the predominant mining method in future years. The Avoca version of SLS is an advantageous method for zones that have suitable conditions for its application. Compared with C&F, it is a higher productivity and lower cost mining method. Furthermore, it is an excellent method for disposing of development waste. Using development waste as backfill saves on the cost of hauling it out of the Mine, reduces ramp congestion, and saves on ventilation for truck haulage.

 

 

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Figure 13-8:                Typical Layout for Longhole Drilling

 

13.3 Geomechanics and Ground Support

 

The geotechnical conditions at El Porvenir result from the rock mass’s characteristics and the Mine’s depth. The host rock and the mineralized zones are generally classified as fair to good, with rock mass ratings (RMR) ranging from 40 to 60. El Porvenir is one of South America's deepest mines, extending more than 1,800 m below the main access level. Its depth contributes to the occurrence of seismic events, including rockbursts.

 

Table 13-11 summarizes information regarding the rock mass characteristics at El Porvenir. The host rock consists mainly of slightly altered limestones and marble. The mineralized zone is moderately altered and consists primarily of skarn, breccia, calcareous breccias, heterolithic breccias, and siliceous breccias. The rock mass has three joint sets of discontinuities and a system of random joints spaced from 50 mm to 600 mm. The discontinuities are generally calcite filled or clean and wet. The rock strengths range from medium to high (60 MPa to 120 MPa). The in-situ stresses are approximately 45 MPa in the middle zone of the Mine and high in the lower zones, exceeding 60 MPa. Table 13-12 presents representative values for major stresses both in magnitude and azimuth that were measured in 2001.

 

 

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Table 13-11:         Rock Mass Characteristics 

Nexa Resources S.A. - El Porvenir Mine

 

Deposit Geology   Description
Host Rock   Slightly altered limestones and marble.
Mineralized Zones   Moderately altered, includes skarn, breccia, calcareous breccias, heterolithic breccias, and siliceous breccias
Deposit Type   Contact metasomatic replacement type polymetallic ore deposit
Alteration Zone   Alteration zone of metamorphism, skarn, and marble in the intrusive-limestone rock contacts.
Strike   Southern bodies and veins strike north-south, northeast, and northwest, and northern structures strike northwest.
Discontinuities   Three joint sets of discontinuities plus random joints system with spacings ranging from 50 mm to 600 mm.  Discontinuities are generally calcite filled or clean and wet.

Intact Rock Properties   Density
(t/m3)
  UCS
(MPa)
Intrusive Rock   2.65 to 2.96   50 to 80
Pyritic Intrusive   3 to 4.2    
Marble   2.7 to 3.1   50 to 250
Limestone   2.7   50 to 100
Mineralization   3.2 to 4.1   50 to 100

Geomechanics Classification
Permanent Workings   Type II rock (RMR: 60–80) to type III rock (RMR: 40–60)
Producing ore zones   Type III rock (RMR: 40–60) and type IV rock (RMR: 20–40)

In-Situ Stresses
Middle Zone   ~ 45 MPa
Lower Zones   > 60 MPa
Water Conditions   Minimal water infiltrations, the rock mass is generally dry.

Sources: SRK, 2017 & Nexa, 2020

 

Table 13-12:           Magnitude and Azimuth of the In-Situ Stresses 

Nexa Resources S.A. - El Porvenir Mine

 

Sigma 1   Azimuth   Dip   Sigma 2   Azimuth   Dip   Sigma 2   Azimuth   Dip
42.4 MPa   90°   16.5°   36 MPa   356°   13°   30 MPa   231°   70°

Source: SRK, 2017

 

 

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Seismic events, including rockbursts, occur due to the high ground pressures associated with the Mine’s depth. Table 13-13 presents information about seismicity and seismic events at El Porvenir. Sudden, violent rock failure (rockbursts) is one of the most critical risks for the operation. Most seismic events originate sufficiently far away from the mine workings that they are not severe enough to impact underground operations.

 

Table 13-13:        Seismic Events 

Nexa Resources S.A. - El Porvenir Mine

 

Seismic Events at El Porvenir
Largest recorded   Mw 1.6 in September 2018. Historically, since 2006, events up to 2.2 have occurred.
Typical events   Mw -0.5 to 1.5
Distances in the rock mass   Typically, 300 m to 500 m from the excavations
Seismic Risk 1.13   The classic formulation of the Gutenberg-Richter model (Model GR, Gutenberg and Richter 1958) is the one most used in the seismic characterization of a source for hazard studies combined with area-type sources.  The recurrence model involves considering a logarithmic relationship between the rate of large and small earthquakes that can occur in a source zone or a fault (or a linear relationship between the logarithm of the rate of large and small earthquakes).

Procedures According to Intensity of Seismic Event
Small   ML < 0    
Medium   ML 0 to 0.8   Temporarily stop work and inspect the area.
Large   ML 0.8 to 1.5   Leave the stopes and shut down operations for one shift.
Very Large   ML > 1.5   Withdraw to a safe zone and shut down operations in the stope and nearby ones for at least two shifts.

    Seismic Magnitude Measurements Used
ML = Linear Magnitude Scale
Mw = Moment Magnitude Scale, measures the size of events in terms of the amount of energy released. Specifically, moment magnitude refers to the amount of rock movement (i.e., the distance of movement along a fault or fracture) and the area of the fault or fracture surface, defined by Hanks & Kanamori (1979).

 Source: Nexa, 2020

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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El Porvenir has implemented measures to minimize the risks associated with seismic events. The Mine’s geomechanical team has a microseismic monitoring system installed in the Mine to monitor seismicity.

 

Figure 13-9 presents the procedures to be followed when a seismic event occurs. The Mine planning team incorporates the following measures in its mine designs:

 

The timing and sequencing of excavations are planned such that yielded ground does not store excessive strain energy.

 

Stope-blast designs minimize the number of mining steps. Blasts are controlled to maintain stability around excavations.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Figure 13-9:          Procedures for Seismic Events

 

 

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Table 13-14 presents El Porvenir’s ground support standards. An excavation’s ground support requirement depends on whether it is permanent or temporary and the quality of its rock in terms of RMR. Split sets are used in temporary mine workings, and resin-rebar bolts are required in permanent ones. Shotcrete containing synthetic fibre is applied when ground conditions are less than favourable.

 

Table 13-14:          Ground Support Procedures 

Nexa Resources S.A. - El Porvenir Mine

 

Excavation
Type
  RMR
Range
  Bolt
Type
  Bolt
Length
  Bolt
Spacing
(m)
  Mesh
Type
  Shotcrete1
Thickness (mm)
  Steel
Sets

  < 30   Split Set   2.1 m   1.00 x 1.00m   Welded   75   -
  30 - 40   Split Set   2.1 m   1.20 x 1.20m   -   50   -
Temporary (< 1 year)   40 - 50   Split Set   2.1 m   1.10 x 1.10m   Welded   -   -
Maximum Span 8 m   50 - 60   Split Set   2.1 m   1.30 x 1.30m   Welded   -   -
  > 60   Split Set   2.1 m   1.50 x 1.50m   -   -   -
                             

  < 20         Avoid Excavating
  20 - 30   Split Set       -   -   50   1.0 m
Permanent (> 1 year)   30 - 40   Split Set   2.1 m   1.10 x 1.10m   Welded   75   -
Maximum Span 6 m   40 - 50   Resin Rebar   2.1 m   1.20 x 1.20m   -   50   -
  50 - 60   Resin Rebar   2.1 m   1.30 x 1.30m   Welded   -   -
  > 60   Resin Rebar   2.1 m   1.50 x 1.50m   Welded   -   -

Note:

 

1. Contains synthetic fibre

 

13.3.1 Recent Geotechnical Studies

 

A number of geotechnical studies have recently been carried out by Nexa (Nexa, 2019c; Nexa 2020h; Nexa, 2021):

 

Geomechanical study for implementing ground support standards;

 

Stability analysis for applying the sublevel stoping method in the CN-03 Vein, Level -890/-910;

 

Stability analysis for applying the sublevel stoping method in the Carmen Cola Vein, Level 3470/3450;

 

Determining the rib pillar for the Éxito Vein, 3550 Level;

 

Determining the maximum longitudinal span for mining the Éxito Vein (3370 Level) with sublevel open stoping;

 

Determining the crown pillar for mining the Porvenir 3 Stope – Upper Zone;

 

Geomechanical study of the Don Ernesto Orebody at El Porvenir Mine; and

 

Evaluation of the seismic hazard at the El Porvenir Mine (Calixto, 2020)

 

 

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13.4 Hydrogeology

 

El Porvenir experiences moderate groundwater inflows and consequently has not developed hydrological models. The average flow of water discharged is 125 L/s. This rate is from all sources, including drilling. Amphos 21 Consulting Perú S.A.C. (Amphos 21) has carried out the following hydrogeological studies related to an environmental impact, shaft deepening, and the tailings dam:

 

Modification of the Environmental Impact Study of the Atacocha Mine - Hydrological and Hydrogeological Study (July 2018)

 

Preliminary Hydrogeological Study for deepening the Picasso shaft (December 2016)

 

Hydrogeological Analysis for Flow Estimation during the Construction of the Winze (October 2014)

 

Hydrogeological Study and Water Balance Support for Raising the El Porvenir Tailings Dam to 4,100 MASL (August 2019)

 

Amphos 21 identified the following hydrogeological systems at El Porvenir:

 

Sub-surface system: It occurs in quaternary sediments and weathered and highly fractured rock. It is associated with shallow and surface water and the principal water bodies and catchments where the mine's infrastructure, including the tailings dam facilities, is located.

 

Depth system: It is hydraulically disconnected from the sub-surface system and occurs adjacent to the underground workings. Water infiltrations towards the mine are minimal. However, some water infiltration occurs in the fractures and drill holes in the mine's western area, close to Milpo-Atacocha fault.

 

13.5 Infrastructure and Mine Services

 

13.5.1 Introduction

 

Table 13-15 summarizes the Mine’s infrastructure and fixed equipment.

 

Table 13-15:          Mine Infrastructure 

Nexa Resources S.A. - El Porvenir Mine

 

Infrastructure   Location   Description
Compressor House   0 Level San Carlos mine entrance   1 x Ingersoll Rand, 298 kW, 85 psig, 1050 cfm
        1 x Ingersoll Rand, 223 kW, 85 psig, 1000 cfm
        2 x Gardener Denver, 130 kW, 85 psig, 700 cfm
La Quinua Tunnel   Level 3620 (-450)   Drainage tunnel
Pump station   Level 3470 (-600)   3 x Stationary pumps Vogel, 450 hp, one of which on standby.
Pump station   Level 3240 (-830)   3 x Stationary pumps Vogel, 600 hp, one of which on standby.
Pump station   Level 3100 (-970)   3 x Stationary pumps Vogel, 250 hp, one of which on standby.
Pump station   Level 2840 (-1230)   3 x Stationary pumps Vogel, 450 hp, one of which on standby.
Auxiliary pump   Level -1370   Submersible pump, 15 hp
Auxiliary pump   Level 1570   Submersible pump, 15 hp

 

 

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Infrastructure   Location   Description
Dewatering Pipe       Steel, 10" Ø
Refuge Station   Level 3650 (-420), Cx 969   20-person capacity, 72 hours
Refuge Station   Level 2460, Spiral 55   20-person capacity, 72 hours
Powder Magazine   Level -440    
Powder Magazine   Level -970    
Maintenance Shop   Level 3470   For rubber-tired mobile equipment
Picasso Shaft   Collar Level (0) 4101.78 MASL   1 Cage + 2 skips, 1,732 m depth
Hoist Room:        
Production Hoist   Level 4070 MASL   2 x 3,000 hp / 2 drum 192" x 72"
Service Hoist   Level 4070 MASL   1,200 hp / 1 drum 120"x72"

 

The following subsections describe El Porvenir’s infrastructure and mine services.

 

13.5.2 Ventilation

 

El Porvenir’s ventilation system provides airflow of approximately 32,000 m3/min to the underground workings. Figure 13-10 illustrates the Mine’s ventilation system.

 

 

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Figure 13-10:              Ventilation System

 

 

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Table 13-16 and Table 13-17 present the balance between intake and return airflows measured at each of the monitoring stations listed. The fresh air enters the Mine via 11 intake points, and the return air is expelled to surface via 11 routes.

 

Table 13-16:            Ventilation Balance - Intake Airflow 

Nexa Resources S.A. - El Porvenir Mine

 

Code   Intake Airflow   Flow
(m3/min)
EP-I-1   Mine Entrance San Carlos 4070 level   2,593.4
EP-I-2   Phase 1 Adit 4070 level   269.7
EP-I-3   Main Drift 4170 level   4,383.0
EP-I-4   Main drift 4120 level   1,299.6
EP-I-5   Mine Entrance 4020 level   356.2
EP-I-6   Porvenir II Ramp 3990 level   1,008.8
EP-I-7   Main Drift 4150 level   6,960.1
EP-I-8   La Quiñua Tunnel 3620 level   4,849.4
EP-I-9   Connecting Drift to Atacocha 4070m level   2,420.5
EP-I-10   Connecting Drift to Atacocha 3370m level   5,535.3
EP-I-11   Don Ernesto Raise 4050 level   2,428.1
    Total   32,104.1

 

Table 13-17:           Ventilation Balance - Return Airflow 

Nexa Resources S.A. - El Porvenir Mine

 

Code   Return Airflow   Flow
(m3/min)
EP-S-1   Pocket Raise 4120 level   1,205.4
EP-S-2   Conventional raise 4120 level   2,277.4
EP-S-3   Exito raise 4170 level   1,571.0
EP-S-1   Porvenir II raise 3970 level   4,383.0
EP-S-1   CN 4 raise 4150 level   7,616.0
EP-S-1   Drift #1 South - 1 3100 level   999.3
EP-S-1   Drift #1 South - 2 2900 level   1,508.7
EP-S-1   Drift #2 South 3630 level   2,901.3
EP-S-1   Drift #4 South 3630 level   1,862.9
EP-S-1   Drift #5 South 3630 level   1,579.8
EP-S-1   Alimak 2 4150 level   8,084.1
    Total   33,988.9

 

 

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The Mine’s total estimated ventilation demand is based on the factors indicated in Table 13-18. As El Porvenir is a mechanized operation, approximately 80% of the requirement is attributable to diesel equipment. Six main ventilation fans with capacities ranging from 90,000 cfm to 210,000 cfm extract the return air from the Mine (Table 13-19). Figure 13-11 presents a 200,000 cfm main ventilation fan both before installation and while in operation.

 

Table 13-18:            Ventilation Requirement 

Nexa Resources S.A. - El Porvenir Mine

 

Item   Flow
(m3/min)
Personnel   2,011.0
Wood   0.0
Temperature   0.0
Diesel Equipment   24,828.9
Leaks   4,026.0
Total   30,865.9
     
Actual Fresh Air Intake   32,104.1
Coverage (%)   104%

 

Table 13-19:          Main Ventilation Fans 

Nexa Resources S.A. - El Porvenir Mine

 

Code   Make   Power
(hp)
  Capacity
(cfm)
  Level
EP-VE-103   Howden   200   90,000   Level 3300 (-770)
EP-VE-107   Zitron   400   200,000   Level 4150 (+80)
EP-VE-110   Zitron   400   200,000   Level 4150 (+80)
EP-VE-116   Airtec   200   100,000   Level 3630 (-440)
EP-VE-43   Joy   400   210,000   Level 4170 (+100)
EP-VE-44   Joy   400   180,000   Level 3620 (-450)

 

 

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Source: Nexa, 2020d 

 

Figure 13-11:        Main Ventilation Fan

 

Secondary fans direct the airflow through the Mine’s secondary ventilation circuits. Table 13-20 presents the system’s main branches. Smaller auxiliary fans and vent ducting ventilate the development headings. Auxiliary fans range from 20,000 cfm to 50,000 cfm in capacity and have electric motors ranging from 40 hp to 100 hp. The fabric type ventilation ducting ranges from 24 in. to 36 in. in diameter. Figure 13-12 presents examples of work headings ventilated with ducting.

 

Table 13-20:         Main Ventilation Branches 

Nexa Resources S.A. - El Porvenir Mine

 

Ventilation Branch   Nominal Capacity
(cfm)
  Intake/Return
Raise CH-3   200,000   Intake
Raise CH-Central   180,000   Intake
Raise Socorro Norte   100,000   Intake
Raise CH-2A   200,000   Return
Raise CH-1   100,000   Return
Raise CH-2   100,000   Return
Raise CN-4   200,000   Return
Raise CH-4&5   200,000   Return

 

 

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Source: Nexa, 2020d

 

Figure 13-12:            Ventilation Ducting Used to Ventilate Work Headings

 

13.5.3 Mine Dewatering

 

El Porvenir's dewatering system discharges water via the La Quinua tunnel. Mine water occurring above the tunnel's elevation drains to it by gravity via drain holes. Water occurring in the levels below the tunnel is pumped to it by the Mine's pumping system. Figure 13-13 illustrates El Porvenir's dewatering system.

 

 

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Figure 13-13:            Mine Dewatering System

 

 

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The water occurring in the stopes, sublevels, and work headings flows by gravity or is pumped to the auxiliary sumps present on each sublevel. The water is then conducted via drain holes and ditches to one of the main sumps and pumping stations. As shown in Figure 13-14, water is pumped sequentially from station to station until it is finally discharged to the La Quinua tunnel. Pump stations are located on levels 2840 (-1230), 3100 (-970), 3240 (-830), and 3470 (-600).

 

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Figure 13-14:               Dewatering Sequence

 

Each station has two sumps with capacities ranging from 400 m3 to 700 m3. The first sump receives the dirty water and allows the sediments to settle out of it. The clean overflow is transferred to the second sump. The water is then pumped to the station on the next higher level or from the 3240 level station to the La Quinua tunnel. The sumps are periodically cleaned by pumping the mud and sediment to old stopes.

 

 

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Each pump station is equipped with three stationary, multi-stage pumps, each with a capacity of 70 m3/h to 90 m3/h. Two of these pumps operate in parallel, while the third one is a standby unit, available to replace either of the others. An automatic system controls the starting and stopping of these pumps. Two independent lines consisting of 10 in. diameter steel pipe extend between the pumping stations and from the uppermost station to the La Quinua tunnel. One of the dewatering lines is in use while the other is on standby.

 

The La Quinua tunnel is the drainage outlet for the Mine’s dewatering system. The water flows via a ditch in the tunnel, exiting through the portal at the town of La Quinua. The water passes through the water treatment plant and then discharges into the Huallaga River. The discharge from the Mine averages 136 m/s. Table 13-21 presents details about the Mine’s dewatering system.

 

Table 13-21:          Dewatering System 

Nexa Resources S.A. - El Porvenir Mine

 

Pump Station   Pump Type   Power
(hp)
  Capacity
(L/s)
    Elevation
(MASL)
  Pumping Height
(m)
La Quinua Water-Treatment Plant                        
                         
Level 3620 (-450) Quinua Drainage Tunnel                   3,620    
                         
Level 3470 (-600) Pump Station   Vogel   450   83   } In parallel        
    Vogel   450   83       3,513.72   158
    Vogel   450   83   Standby        
                         
Level 3240 (-830) Pump Station   Vogel   600   90   } In parallel        
    Vogel   600   90       3,281.81   247.4
    Vogel   600   90   Standby        
                         
Level 3100 (-970) Pump Station   Vogel   250   73   } In parallel        
    Vogel   250   73       3,120.89   158
    Vogel   250   73   Standby        
                         
Level 2840 (-1230) Pump Station   Vogel   450   83   } In parallel        
    Vogel   450   83       2,874.98   200
    Vogel   450   83   Standby        
                         
Level -1370 Auxiliary Pump   Auxiliary pump   15           2,879.82   60
                         
Level -1570 Auxiliary Pump   Auxiliary pump   15                

 

 

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Pump Station   Pump Type   Power
(hp)
  Capacity
(L/s)
  Elevation
(MASL)
  Pumping Height
(m)
Level -1570 Auxiliary Pump   Auxiliary pump   15             

 

While part of the mine water originates from groundwater inflows, drilling, and other mine operations, most of it comes from backfilling. When hydraulic backfill is placed in a C&F stope, it requires a sufficient water content to flow as a slurry through the backfill pipeline. Once the backfill is placed in the stope, the water drains out of it over several days. The water percolates through the backfill material and drains out through the barricades that seal the attack ramps. The barricades are lined with textile, and the water filters through it. The tailings component of the backfill remaining in the stope has a consistency similar to fine sand. The water drained from the barricades flows or is pumped to the auxiliary sumps on the sublevel. Figure 13-15 illustrates the process of draining backfill from a stope.

 

 

Figure 13-15:           Drainage from Backfilling Stopes

 

13.5.4 Compressed Air

 

The Mine’s compressed air is supplied by four compressors (Table 13-15, Mine Infrastructure) installed in a compressor house situated at the San Carlos entrance (0 level). These units have a combined nominal capacity of 3,450 cfm. Compressed air is supplied to the underground working areas via a system of pipes.

 

13.5.5 Water Supply

 

Seven tanks and pipes with 2 in., 3 in., and 4 in. diameters supply the Mine’s industrial water. Table 13-22 lists the locations and capacities of the water tanks.

 

 

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Table 13-22:        Water Tanks 

Nexa Resources S.A. - Mina El Porvenir

 

Location   Capacity
(m3)
Level +170   180
Level +80   165
Level -280   400
Level -360   300
Level -600   180
Level -700   188
Level -970   200

 

13.5.6 Backfill

 

Backfill plays a critical role in a stope’s ground support by filling the opening left from excavating the ore. Backfill also serves as a floor for mining the next higher up cut in the case of C&F and the next higher up intersublevel horizon in SLS. El Porvenir’s mining operations use two types of backfill:

 

Unconsolidated hydraulic backfill

 

Loose rockfill

 

Rockfill consists of waste blasted in development headings. C&F stopes can be backfilled with up to 70% rockfill, while hydraulic backfill must fill the remaining opening. SLS (Avoca) stopes are backfilled with rockfill only. Any waste that cannot be used as backfill must be hauled via truck to surface where it may be used for civil work on the tailings dam.

 

Figure 13-16 illustrates the hydraulic-backfill system, and Table 13-23 provides information about the backfill’s preparation and distribution. Table 13-24 presents the design criteria for hydraulic backfill, which is a slurry consisting of mill tailings from the processing plant that have been classified to remove the fine particles. A bank of hydrocyclones achieves this classification process. The coarser component, which is suitable for backfill, is separated as the underflow. The fine tailings in the overflow are disposed of in the TSF.

 

 

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Figure 13-16:           Hydraulic Backfill System

 

Table 13-23:              Hydraulic Backfill Preparation and Distribution 

Nexa Resources S.A. - El Porvenir Mine

 

Item   Description
Warman Pump, 10x8, EM 8032, 175 hp   Pumps tailings from processing plant thickener to backfill plant
Nest of 8 hydrocyclones, CAVEX D10   Overflow (fines) goes to the tailings pond
    Underflow used for backfill
Warman 8x6, 50 hp Pumps   Pump overflow to either of two tailings ponds
Denver 5x4, 30 hp   Two pumps pump backfill mixture to storage tanks
Storage Tank #1, 400 m3,   Stores backfill mixture (1,200 t capacity)
Storage Tank #2, 400 m3   Holds water used to flush backfill lines
Agitators   Two 11 m3 agitators keep pulp at 1,750 g/L to 1,950 g/L for Low Area and 1,650 g/L to 1,800 g/L for the High Area
Mars H180 S Pump, 250 hp   Pumps hydraulic backfill via 4 in. dia. pipeline to the higher-elevation zones

 

 

 

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Item   Description
Lines #1 and #2   Hydraulic backfill flows to lower levels by gravity via boreholes
Distribution Piping Network    
• From plant to -100 (3070) level   Polyethylene pipe with 5 in. external diameter, 500 m in length
• From -100 (3970) level to the raise   Polyethylene pipe with 4 in. external diameter
• From the raise to the stopes   Polyethylene pipe with 3i n. external diameter

 

Table 13-24: Design Criteria of Hydraulic Backfill 

Nexa Resources S.A. - Mina El Porvenir Mine

 

Parameter   Units   Value
Pulp density low area   g/L   1,750 to 1,950
Pulp density high area   g/L   1,650 to 1,800
% solids low area   %   63.77
Quantity pulp low area   m3/hr   54
Percolation time   cm/hr   2.44
D60/D10       5.23
Aggressiveness       Low

 

Until the Mine is ready to receive it, the backfill is stored at the hydraulic backfill plant in two tanks, which keep the tailings suspended as a slurry (Figure 13-17). The backfill supplied to El Porvenir’s Upper Zone is pumped with a Mars Pump. This part of the system has a capacity of 30,000 t/month. The backfill supplied to the Intermediate Zone flows by gravity through the Mine’s reticulation system. This part of the system has a capacity of 60,000 t/month.

 

 

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Figure 13-17: Hydraulic Backfill Plant

 

13.5.7 Emergency Egress and Mine Rescue

 

Figure 13-18 illustrates the Mine’s emergency egress routes and shows the locations of two refuge stations. The refuge stations are set up for Mine rescue purposes and can accommodate 20 individuals for up to 72 hours (Table 13-15, Mine Infrastructure). Table 13-25 lists the routes available for exiting the Mine.

 

Table 13-25: Exits to Surface 

Nexa Resources S.A. - El Porvenir Mine

 

Exit   Description
1   Level 0, where the Picasso Shaft is located
2   Via the Principal Spiral Ramp, which communicates to surface at level -50
3   Level +80 by Ramp
4   Level -450, connecting to surface via the La Quinua tunnel.

 

 

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Figure 13-18: Emergency Egress Routes and Refuge Stations

 

 

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13.5.8 Electric Power

 

El Porvenir has the following three sources of electric power:

 

Paragsha II Substation

 

La Candelaria Hydroelectric Plant

 

Standby power from generators

 

Table 13-26 describes electrical power supply for the El Porvenir operation. Figure 13-19 illustrates the electrical system for the Mine in a one-line diagram.

 

Table 13-26: Supply of Electric Power 

Nexa Resources S.A. - El Porvenir Mine

 

Electric Power Source #1: Paragsha II Substation

 

The Paragsha II Substation is located in the nearby city of Cerro de Pasco and is part of the national electric power grid (Sistema Interconectado Nacional).

 

The Paragsha II Substation supplies electric power at 138 kV to the Milpo Substation via a 12.57 km long transmission line.

 

The Milpo Substation has two 25 MVA transformers operating in parallel that step down the voltage from 138 kV to 50 kV.

 

The Milpo Substation supplies electric power at 50 kV to #3 Substation via a 0.88 km long transmission line.

 

Substation #3 has two transformers operating in parallel that step down the voltage from 50 kV to 13.2 kV.

 

The Milpo Substation also supplies electricity at 50 kV to the Nueva Chicrin Substation, which provides power for the Atacocha Mine.

 

Electric Power Source #2: La Candelaria Hydroelectric Plant

 

The La Candelaria Hydroelectric Plant is located in La Quinua and has a capacity of 5.5 MVA.

 

The hydroelectric plant supplies electric power at 50 kV to the secondary side of the Milpo Substation via a 2.94 km-long transmission line.

 

The Milpo Substation supplies electric power to #3 Substation, which steps down the voltage from 50 kV to 13.2 kV.

 

Electric Power Source #3: Standby Generators at Substation #2

 

Substation #2 has four Sulzer generator sets that provide standby power.

 

These generators produce electricity at 460 V, have a combined capacity of 2.3 MVA, and are rated at 100 kW, 250 kW, 450 kW, and 750 kW, respectively.

 

In case of an interruption of supply from the national electric power grid, the generators and hydroelectric plant can provide electricity for operating critical services such as ventilation fans and pumps.

 

The voltage of the electricity produced by the generators is stepped up from 460 V to 13.2 KV.

 

Substation #2 can provide power at 13.2 kV to the secondary side of Substation #3 and to the main Substations #10 and #11, which supply the Picasso Shaft.

 

These substations subsequently reduce the voltage to 2.4 kV.

 

Substation #2 also has transformers that step down the voltage from 13.2 kV to 2.4 kV and can connect to secondary substations located underground, including Substations #121 and #123.

 

These secondary substations step down the voltage from 2.4 kV to 440 V and supply power for pumps and other equipment.

 

Distribution of Electric Power to the Underground Mine: Substation #3

 

Substation #3 distributes electric power to the main underground substations, which reduce to the voltage from 13.2 kV to 2.4 kV

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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These main substations supply power to secondary substations throughout the mine.

 

The secondary substations reduce the voltage from 2.4 kV to 440 V for operating ventilation fans, pumps, and other equipment.

 

Source: Nexa, 2020d

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Figure 13-19: One-Line Diagram of the El Porvenir Electrical System

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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The Paragsha II Substation is located in the nearby city of Cerro de Pasco and is part of the national electric power grid (Sistema Interconectado Nacional), and supplies electric power at 138 kV to the Milpo Substation via a 12.57 km long transmission line. The Milpo Substation has two 25 MVA transformers operating in parallel that step down the voltage from 138 kV to 50 kV. The Milpo Substation supplies electric power at 50 kV to #3 Substation via a 0.88 km long transmission line and also supplies electricity at 50 kV to the Nueva Chicrin Substation, which provides power for the Atacocha Mine.

 

The La Candelaria Hydroelectric Plant is located in the town of La Quinua and has a capacity of 5.5 MVA. It supplies electric power at 50 kV to the secondary side of the Milpo Substation via a 2.94 km long transmission line. The Milpo Substation provides electric power to #3 Substation, which steps down the voltage from 50 kV to 13.2 kV.

 

El Porvenir has four Sulzer generators at Substation #2. These are standby units and are available to provide power in case of an interruption of supply from the national electric power grid. The generators working together with the La Candelaria Hydroelectric Plant can provide power for operating critical services such as ventilation fans and pumps. The four units are rated at 100 kW, 250 kW, 450 kW, and 750 kW, respectively, and have a combined capacity of 2.3 MVA. They produce electricity at 460 V, which is stepped up to 13.2 kV.

 

Substation #2 can provide power at 13.2 kV to the secondary side of Substation #3 and to the main Substations #10 and #11, which supply the Picasso Shaft. These latter substations reduce the voltage to 2.4 kV. Substation #2 also has transformers that step down the voltage from 13.2 kV to 2.4 kV and connect to secondary substations located underground, including Substations #121 and #123. These secondary substations step down the voltage from 2.4 kV to 440 V and supply power for pumps and other equipment.

 

Substation #3 serves as a central hub for distributing El Porvenir’s power and consists of two transformers operating in parallel that step down the voltage from 50 kV to 13.2 kV. It distributes electric power to the main underground substations, which reduce the voltage to 2.4 kV. The main substations supply electricity to the secondary substations throughout the mine. These, in turn, reduce the voltage from 2.4 kV to 440 V for operating ventilation fans, pumps, and other equipment. Figure 13-20 and Figure 13-21 illustrate the standard layout of a substation and electrical equipment, respectively.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Figure 13-20: Standard Layout for an Underground Electrical Substation – Plan View

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Figure 13-21: Electrical Equipment in a Typical Substation

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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13.5.9 Communications

 

El Porvenir has a leaky-feeder system for communications and data transmission underground. The system consists of the installation of a special coaxial cable that acts as an antenna along its length for two-way radio communication. It is called “leaky” because the cable has slots cut into its outer shield enabling it to emit and receive radio signals as a radiating cable. The system requires line-of-site positioning between the cable and the handset or other device. Consequently, the coaxial cable must be extended along a drift or other heading advances to maintain full communications capability.

 

Should El Porvenir plan on upgrading its underground data communications capabilities, it should consider replacing the leaky-feeder system with a high speed digital network based on Wi-Fi or LTE technology. Leaky feeder’s low frequency limits its data transferring capacity and hence its compatibility with mining’s increasingly data driven technologies.

 

As the Mine has extensive existing workings, a private 4G-LTE network could be an attractive option. A private 4G-LTE network can provide substantial level coverage with a lower installation requirement than alternative systems as it sends a reliable signal over long distances without coaxial cables, amplifiers, or access points. Furthermore, it is not limited to line-of-site transmission.

 

A high speed digital network will permit El Porvenir to implement centralized control and monitoring of underground operations from a control room on surface. These centralized functions can include real time tracking of personnel and equipment, telemetry, ventilation on demand (VOD), seismic monitoring, and closed circuit television, among other applications.

 

With a high speed digital network, El Porvenir could implement automated and/or tele-remote technology to operate equipment from control stations on surface. The technology can be used for mucking development headings, crushing, and operating rockbreakers, etc. A significant benefit is that it allows many mining operations to continue during otherwise non-productive periods, including lunch breaks, shift changes, blasting times, and ventilating smoke. SLR does not, however, consider automated/tele-remote technology a practical option for mucking stopes or production drilling, as automation technology is not compatible with El Porvenir’s mining methods and orebody configuration.

 

With an upgraded communications system, El Porvenir could implement tele-remote mucking of development headings. After blasting the round and during shift change, the operator could run the LHD from a control station on surface. With this procedure, the heading could be mucked out and ready for ground support as soon as the oncoming crew arrives at the workplace underground.

 

13.5.10Transport and Material Handling

 

The underground transportation and materials handling system at El Porvenir has the following components:

 

Ramps

 

Orepasses

 

Track haulage level

 

Picasso Shaft

 

Conveyor

 

El Porvenir has several ramp systems that provide access to the levels and sublevels. Most of the ramps have a spiral configuration and coil from sublevel to sublevel over a vertical interval of typically 20 m. While the Mine uses most of the development waste as rockfill to backfill the stopes, approximately 10% to 30% of it must be hauled to surface via the ramps.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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The ore produced in the C&F and SLS stopes is transported to and dumped in orepasses by LHDs. These orepasses extend to the 2,900 track haulage level (-1170), where the ore is pulled from chutes and loaded onto mine cars. The mine cars dump at an orepass grizzly, and the ore is transferred to the Picasso Shaft’s loading pocket on the 2,500 level. From there, the ore is loaded onto skips and hoisted via the shaft to the ore dump. After being discharged at the dump, the ore is transferred to the underground crushing plant. Crushed ore is transported to the surface and the processing plant via a conveyor in an inclined drift.

 

With a shaft depth of 1,732 m, the El Porvenir shaft is the deepest in South America (southamericatotheworld.com). Information about the Picasso Shaft is presented Table 13-27. The Picasso Shaft consists of a cage for transporting personnel and two counterbalanced skips for hoisting ore. It is not set up for hoisting waste. Nexa plans to upgrade the Picasso Shaft by replacing the wood sets in its upper portion with steel ones. This upgrade will permit higher hoisting speeds increasing its ore hoisting capacity.

 

Table 13-27: Picasso Shaft 

Nexa Resources S.A. - El Porvenir Mine

 

Item   Description
Production hoist   2 x 3,000 hp, two drum 192” x 72”
Service hoist   1,200 hp, single drum 120” x 72”
Hoisting rope - production hoist   2 1/4” diameter
Hoisting rope - service hoist   1 1/4” diameter
Hoistroom - production hoist   Level 4070 MASL
Hoistroom - service hoist   Level 4070 MASL
Shaft collar level   San Carlos level, Level (0) 4101.78 MASL
Shaft bottom   2370 MASL
Shaft depth   1,732 m
Skips   2 skips counterbalanced
Skips, hoisting speed   3,000 feet per metre (fpm) nominal, 2,000 fpm in operation
Skip payload   16 t/skip nominal capacity, 13 t/skip in operation depending on ore grade.
Cage   9 Persons per deck, 2 decks
Cage, maximum hoisting speed   1,254 fpm
Loading pocket   Level (-1570) 2500 MASL
Ore dump   Level 4070 MASL
Tramming level   Level 2900 (-1170)
Underground crushing plant   Level 4060 MASL, Hewitt Robins 30” x 42”, 150 hp, 300 t/h, 4.5” opening

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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13.6 Mine Equipment

 

El Porvenir is a highly mechanized mining operation and consequently has a considerable quantity of equipment. Table 13-28 and Table 13-29 present information about the Mine’s trackless mobile equipment and track equipment, respectively. Table 13-15 (Mine Infrastructure) and Table 13-27 (Picasso Shaft) provide information about fixed pieces of equipment, including the Picasso Shaft’s hoisting plant. To achieve its production and development targets, El Porvenir strives to achieve the mechanical availabilities indicated in Table 13-30 for strategic equipment.

 

Table 13-28: Trackless Mobile Equipment 

Nexa Resources S.A. - El Porvenir Mine

 

 

Type

 

Make

 

Model

 

Nexa

Contractors

Seprocal1

Iesa2

Incimmet3

Unicon4

Underground Loader 3.5 yd3 Caterpillar R1300G 1 - - - -
Underground Loader 6.0 yd3 Caterpillar R1600G 6 - - - -
Underground Loader 6.0 yd3 Caterpillar R1600H 2 3 6 - -
Underground Loader 6.0 yd3 Atlas Copco ST 1030 - 1 - - -
Jumbo Tamrock DD410 1 - - - -
Jumbo Sandvik DD411-60 1 - - - -
Jumbo Sandvik DT821 2 - - - -
Jumbo EPIROC Boomer S1D - 3 6 - -
Scaler BTI H519BX10 2 - - - -
Scaler BTI HS18 1 - - - -
Scaler BTI VPS25 1 - - - -
Scaler Paus 853-S8 - 3 3 - -
Bolter MacLean MEM-928 & 946 6 - - - -
Bolter Resemin Bolter 88 - 3 - - -
Bolter EPIROC BOLTEC S - - 4 - -
Scissor Lift BTI SL6-812 1 - - - -
ANFO Loader Normet Charmec 6605B 1 - - - -
ANFO Loader MacLean AC3 3 - - - -
ANFO Loader Mercedes Benz ATEGO 1726 / 42 - - 3 - -
Forklift Caterpillar DP70NM 1 - - - -
Production Drill Rig Resemin Raptor 552 R - - - 1 -
Cable Bolter Tamrock Cabolt 7-5 - - - 1 -
Dump Trucks VOLVO FM500 6X4R - - 10 - -
Dump Trucks SANDVIK EJC-417 - - 1 - -
Dump Trucks EPIROC MT2010 - - 1 - -
Dump Trucks EPIROC MT2200 - - 1 - -
Dump Trucks Sandvik TH-320 - 1 - - -

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Type

 

Make

 

Model

 

Nexa

Contractors

Seprocal1

Iesa2

Incimmet3

Unicon4

Dump Trucks Atlas Copco MT-2010 - 4 - - -
Shotcrete Sprayer Putzmeister Wetcret SPM 4210 - - - - 5
Shotcrete Sprayer Putzmeister Mixkret4 - - - - 11

 

Notes:

 

1. Operaciones Seprocal S.A.C. (Seprocal)
2. Iesa S.A. (Iesa)
3. Ingenieros Civiles Mineros y Metallurgistas S.A. (Incimmet)
4. Unión de Concreteras S.A. (Unicon)

 

Table 13-29: Track Equipment 

Nexa Resources S.A. - El Porvenir Mine

 

Type   Make   Model   Quantity
Trolley Locomotive   Goodman   15 ton 36 in. gauge   2
Trolley Locomotive   IMIM   LT-15   1
Mine Cars   Kiruna   04 m3   22

 

Table 13-30: Required Mechanical Availability for Strategic Equipment 

Nexa Resources S.A. - El Porvenir Mine

 

Equipment   Mechanical
Availability
    Quantity  
6 yd3 LHD     93 %     9  
Jumbo     85 %     5  
Scissor Lift     85 %     5  
ANFO Loader     80 %     2  
Scaler     85 %     4  
Locomotive     90 %     3  
Hoisting System     90 %     1  

 

13.7 Personnel

 

The workforce of El Porvenir’s mining operations consists of Nexa personnel and employees of the following contractors:

 

Seprocal

 

Iesa

 

Incimmet

 

Unicon

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Production at El Porvenir is carried out by Nexa mine personnel, while contractors carry out development. Table 13-31 lists the Nexa personnel involved with underground operations at El Porvenir. The Mine operates on two 12 hour shifts providing 24/7 coverage. Mine personnel work a 14 x 7 shift cycle consisting of seven days of dayshift, seven days of nightshift, and seven days off.

 

Table 13-31: Nexa Personnel - Underground Mine 

Nexa Resources S.A. - El Porvenir Mine

 

Area   Qty   Comments
Personnel on Shift Work   89   < 12 hour shift
Personnel on Time Off   44   < Shift cycle 14 days working on-site x 7 days off
Personnel with Restrictions   48   < Personnel with risk (>65, medical restriction) + Permanent union leave
Mine Supervision   18   < Including personnel on time off
Technical Services Staff   6   < Including personnel on time off
Total Nexa   205    

Source: Nexa

 

13.8 Life of Mine Plan

 

At El Porvenir, mine design and planning are conducted using Deswik software. The life of mine (LOM) plan is based on operations continuing until 2028. Table 13-32 presents the mine production schedule broken down by metal grades on a annual basis until 2028. Mine output remains stable at present levels until 2024 but then progressively declines over the remaining years of operations. Table 13-33 breaks down the production by mining method. The share of the output originating from SLS increases steadily from 19% in 2021 to 84% in 2025 and then drops over the final three years of operations. Table 13-34 breaks down the production by mining zone. The share of output originating from the Mine Deepening Zone increases progressively from almost nil in 2021 to 66% in 2027. Table 13-35 presents El Porvenir’s LOM development schedule, broken down by heading and expenditure type.

 

Table 13-32: Mine Production Schedule 

Nexa Resources S.A. - El Porvenir Mine

 

    Units   Total   2021   2022   2023   2024   2025   2026   2027   2028
Ore Total   000 t   13,850   2,161   2,222   2,220   2,036   1,658   1,380   1,371   802
Stopes   000 t   12,743   2,001   2,008   2,029   1,879   1,524   1,270   1,309   724
Develop   000 t   1,107   160   214   191   157   134   110   62   79
Zn   %   3.75   3.28   3.69   3.57   3.82   4.11   4.25   4.01   3.39
Pb   %   0.88   1.12   0.92   1.02   0.96   0.71   0.67   0.66   0.70
Cu   %   0.23   0.17   0.21   0.24   0.25   0.24   0.27   0.28   0.21
Ag   g/t   62.8   72.5   61.6   66.6   61.9   52.3   56.6   59.1   70.0
NSR   US$/t   98.54   95.91   97.27   98.20   100.48   99.56   103.22   99.99   92.61

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Table 13-33: Mine Production by Mining Method 

Nexa Resources S.A.- El Porvenir Mine

 

    Units   Total   2021   2022   2023   2024   2025   2026   2027   2028
Cut and Fill                                        
Ore Mined   000 t   9,319   1,823   1,480   1,493   1,148   902   976   983   514
ZnEq Grade   %   4.93   4.83   4.75   4.88   4.83   5.15   5.15   5.22   4.73
Grade Zn   %   3.48   3.20   3.41   3.29   3.56   4.20   3.81   3.76   2.59
Grade Pb   %   0.97   1.17   0.94   1.11   0.91   0.69   0.79   0.86   1.07
Grade Cu   %   0.18   0.15   0.16   0.18   0.20   0.22   0.21   0.23   0.15
Grade Ag   g/t   69.0   73.4   64.4   69.0   61.0   54.7   68.1   74.0   99.8
Development   m   70,117   20,519   12,216   11,573   10,061   7,926   4,560   2,209   1,052
                                         
Sublevel Stoping                                        
Ore Mined   000 t   4,531   338   742   727   888   756   404   388   289
ZnEq Grade   %   5.17   5.02   5.33   5.30   5.44   4.88   5.55   4.71   4.68
Grade Zn   %   4.30   3.72   4.24   4.14   4.16   4.01   5.31   4.64   4.81
Grade Pb   %   0.71   0.83   0.87   0.82   1.03   0.74   0.37   0.17   0.06
Grade Cu   %   0.33   0.31   0.30   0.38   0.31   0.25   0.40   0.42   0.32
Grade Ag   g/t   50.4   67.5   56.3   61.6   63.5   49.8   28.6   21.5   16.8
Development   m   58,868   3,593   10,284   10,842   12,414   8,741   6,032   3,584   3,377
                                         
From All Sources                                        
Ore Mined   000 t   13,850   2,161   2,222   2,220   2,036   1,658   1,380   1,371   802
ZnEq Grade   %   5.01   4.86   4.94   5.01   5.10   5.03   5.26   5.08   4.71
Grade Zn   %   3.75   3.28   3.69   3.57   3.82   4.11   4.25   4.01   3.39
Grade Pb   %   0.88   1.12   0.92   1.02   0.96   0.71   0.67   0.66   0.70
Grade Cu   %   0.23   0.17   0.21   0.24   0.25   0.24   0.27   0.28   0.21
Grade Ag   g/t   62.8   72.5   61.6   66.6   61.9   52.3   56.6   59.1   70.0
Total ZnEq   000 t   693   105   110   111   104   83   73   70   38
Development   m   128,985   24,113   22,500   22,416   22,475   16,667   10,592   5,793   4,429

 

Table 13-34: Production by Mining Zone 

Nexa Resources S.A. - El Porvenir Mine

 

Mining Zones   Units   Total   2021   2022   2023   2024   2025   2026   2027   2028
Upper Mine Zone   000 t   4,069   758   722   795   542   248   361   362   281

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Mining Zones   Units   Total   2021   2022   2023   2024   2025   2026   2027   2028
Intermediate Zone   000 t   4,470   957   815   831   843   572   100   100   251
Lower Mine Zone   000 t   1,380   443   425   207   118   143   45   0   0
Mine Deepening Zone   000 t   3,932   4   259   387   533   695   874   909   270
Total   000 t   13,850   2,161   2,222   2,220   2,036   1,658   1,380   1,371   802

 

Table 13-35: Development Schedule 

Nexa Resources S.A. - El Porvenir Mine

 

    Unit   Total   2021   2022   2023   2024   2025   2026   2027   2028
Horizontal Development                                        
Capital Development   m   63,867   11,817   11,058   11,785   13,114   9,071   4,378   1,319   1,325
Operating Development   m   65,118   12,296   11,442   10,630   9,361   7,596   6,214   4,474   3,104
Total   m   128,985   24,113   22,500   22,416   22,475   16,667   10,592   5,793   4,429
                                         
Vertical Development   m   2,582   485   458   352   465   333   294   67   129
                                         
Heading Type                                        
Access   m   14,495   5,332   2,942   2,081   1,639   1,632   686   45   138
Haulage   m   19,732   3,342   4,586   3,808   3,184   2,848   1,775   190   0
Ore Access   m   18,856   2,491   2,939   3,432   3,540   2,632   1,642   1,513   668
Ore Drive   m   31,757   4,423   5,603   5,118   4,182   3,332   3,886   2,916   2,298
Orepass Drive   m   545   90   153   71   154   78   0   0   0
Electrical Substation   m   529   95   93   116   117   109   0   0   0
Ramp   m   27,407   6,908   3,847   4,775   5,281   2,985   1,833   830   947
Sump   m   583   46   34   25   330   147   0   0   0
Vent Drive   m   5,842   552   727   769   1,584   1,812   239   70   90
Crosscut   m   9,237   835   1,576   2,222   2,466   1,091   531   229   288
Total   m   128,985   24,113   22,500   22,416   22,475   16,667   10,592   5,793   4,429

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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14.0 Processing and Recovery Methods

 

El Porvenir concentrator has an ore processing capacity of approximately 2.2 Mtpa and consists of conventional crushing, grinding, and flotation to produce copper, lead, and zinc concentrates. El Porvenir copper and lead concentrates are sold to traders and delivered by road and rail to Callao which is approximately 270 km by road for shipping overseas, while zinc concentrate is transported by road and rail to Nexa’s Cajamarquilla zinc refinery near Lima. El Porvenir is approximately 315 km from Lima by road.

 

14.1 Process Description

 

A simplified flow sheet for El Porvenir concentrator is provided in Figure 14-1. The concentrator processes on average approximately 5,800 tpd to 5,900 tpd.

 

Primary crushing takes place underground at El Porvenir using a 30 in. x 42 in. jaw crusher. The product of the primary crusher with a top size of approximately 4.0 in. to 4.5 in. (100 mm to 125 mm) is transported by conveyor to the 30,000 t coarse ore stockpile at surface. Ore is reclaimed from the coarse ore stockpile by two feeders and transferred to a conveyor feeding a primary screen. Oversize from the screen reports to the secondary cone crusher while the screen undersize (top size of 10 mm) reports to the grinding circuit feed bins. Secondary crusher product with a top size of 30 mm reports to a three-way splitter that splits the material between three secondary screens. Oversize from these screens is fed to two tertiary crushers while screen undersize (top size of 10 mm) reports to the grinding circuit feed bins. Tertiary crusher product is returned to the secondary screens.

 

The grinding circuit consists of two primary ball mills and five secondary ball mills. Crushed ore is fed from the two grinding circuit feed bins to the two primary ball mills. Discharge from the primary ball mills reports to two flash flotation cells which produce lead concentrate that reports to the final lead concentrate storage tank and tails that undergo high frequency vibrational screening. Coarse material from the classifiers reports to the secondary ball mills while fine material or overflow from the classifiers is combined in a mixing box, a portion of which is directed to an additional flash flotation step also producing lead concentrate while the remainder (as well as the tails from this flotation step) report to bulk flotation conditioning.

 

The bulk flotation circuit consisting of bulk rougher, scavenger, and cleaner cells produces a copper and lead concentrate. Bulk scavenger concentrate is reground before being returned to the roughers. Bulk flotation is followed by copper-lead separation consisting of copper roughers, scavengers, and cleaners, during which copper minerals are floated while lead minerals are depressed to produce separate copper and lead concentrates. Tails from the bulk flotation circuit go on to feed the zinc flotation circuit.

 

Tails from the bulk flotation circuit undergo three stages of conditioning prior to zinc flotation. The zinc flotation circuit consists of zinc roughers, scavengers, and three stages of cleaning to produce zinc concentrate and final tails.

 

Concentrates are dewatered in thickeners (lead and zinc) and a dewatering cone (copper) followed by a filter press for zinc concentrate and disc filters for lead and copper concentrates. The filtered concentrates are stored in covered stockpiles prior to being loaded into trucks using a front-end loader. Water from concentrate dewatering is recycled for use in the process. Lead and zinc concentrate moisture content is approximately 8% to 9%, and copper concentrate moisture content is approximately 11%.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Tailings at approximately 22% solids are classified in cyclones, with coarse material in the underflow at approximately 62% solids sent to the hydraulic backfill plant for use in the Mine as backfill. Mine backfill constitutes approximately 50% of tailings produced. Water from tailings dewatering is returned to the process. Overflow from the cyclones containing the fine tailings is deposited in the conventional TSF adjacent to the Mine and processing plant. Tailings can be discharged at various points in the TSF by means of valved discharge points on the tailings line. Clarified water discharged from the TSF joins natural water flows used to generate electricity in Nexa’s La Candelaria Hydroelectric Plant.

 

14.2 Energy, Water, and Process Materials Requirements

 

Power requirements for the processing facilities are not anticipated to change significantly in the foreseeable future from the current power requirements.

 

Make-up water is supplied from various creeks around the TSF, as well as the Carmen Chico River, approximately 3.2 km south of the processing facility. Water consumption is not expected to change significantly from the recent historical water usage and no supply concerns have been noted.

 

Key reagents used in the process include lime, sodium cyanide, sodium isopropyl xanthate (SIPX), methyl isobutyl carbinol (MIBC), copper sulphate, zinc sulphate, and collectors for copper, lead, and zinc.

 

14.3 Manpower

 

The processing plant personnel number 63. Maintenance (124), technical services (28), and projects personnel (nine) service the Mine and other departments in addition to the processing plant. These numbers are not anticipated to change significantly in the foreseeable future.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Figure 14-1: Process Flow Sheet

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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15.0 Infrastructure

 

A combination of transportation methods, including road access, aircraft via Huánuco, and rail to Cerro de Pasco are used to supply the Mine. Off-site infrastructure includes facilities for the transfer of concentrate from truck to rail at Cerro de Pasco to transport concentrate for export by train to the port of Callao. Mine access is via a 13 km dirt road northeast from Cerro de Pasco, and paved road from Lima to Cerro de Pasco (approximately 315 km).

 

The main road from Lima to Cerro de Pasco is used for personnel transportation, supply of food, reagents, spare parts, mining supplies, and diesel fuel. Huánuco airport can be used for personnel transportation and emergency situations.

 

The site comprises an underground mine, TSF, waste rock stockpiles, an ore processing facility with associated laboratory and maintenance facilities, and maintenance buildings for underground and surface equipment. Additional facilities and structures include an office building, change house facilities, main shaft, ventilation shaft, backfill plant, explosives storage area, hydroelectric power generating plant, power lines and substation, fuel storage tanks, a warehouse and laydown area, and an accommodation camp.

 

15.1 Power Plant and Distribution

 

The power supply for the Mine comes from two sources:

 

The national power grid via a 50/13.8 kV main substation located near the Mine,

 

The La Candelaria Hydroelectric Plant, which consists of three turbines (0.5 MVA, 1.2 MVA and 3.5 MVA), is connected to the Mine through the main substation by a 4.6 km long 50 kV transmission line.

 

Power is generated at 4,660 kV at the La Candelaria Hydroelectric Plant. All other project loads are fed at 13.8 kV from the main substation through overhead power lines. These power lines are used to deliver power to various locations to support activities during operation of the Mine.

 

15.2 On-Site Roads

 

Mine site roads include main roads suitable for mining trucks that transport concentrates to Cerro de Pasco and Lima and service roads for smaller vehicles. The site roads are used by authorized mine personnel and equipment, with access controlled by Nexa.

 

A network of approximately 15 km to 20 km of service roads has been built providing access to the underground mine, processing plant, TSF, waste rock stockpiles, mine offices, workshops, mine camps, and other surface infrastructure. The roads are approximately six metres wide designed for two-way 15 m3 truck traffic and road maintenance equipment.

 

15.3 Utilities and Services

 

Raw water is sourced from a small creek, Tingovado, as well as from other creeks around the TSF.

 

Fresh water supply is obtained from the Carmen Chico River, approximately 3.2 km south of the processing facility. This water is primarily for use in the mine camps and make-up requirements for the processing facility and industrial area.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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15.4 Sewage Collection and Disposal

 

A sewage treatment facility has been constructed south of the industrial and mine camp sites at a lower elevation. Buried sewer pipes collect sewage from the site and transfer it to the treatment facility. The treatment facility consists of two independent containerized treatment lagoon systems providing redundancy if one unit must be shut down for maintenance. The system is capable of treating all of the wastewater generated in the camp, industrial, and office areas. Treated effluent is released to the TSF via a small stream.

 

15.5 Site Security

 

The principal site entry point on the access road from Cerro de Pasco consists of a lighted security gate and vehicle access barrier. A gatehouse provides sanitary facilities, communications equipment, and search facilities including metal detection. A weighbridge is located close to the gatehouse to enable load monitoring of incoming and outgoing vehicles.

 

15.6 Communication and IT Systems

 

Point-to-point satellite communication is the main communication system between the Mine and the outside world. The system includes voice/data/video/fax, internet, and VPN services, including bidirectional links between the Mine site and Lima.

 

Satellite television for entertainment, cellular communication, and FM radio is provided by local service providers.

 

15.7 Vehicle Fueling Facility and Mine Equipment Ready Line

 

The vehicle fueling facility and ready line is located adjacent to the processing plant. The fueling facility stores diesel and gasoline. Smaller tanks hold a variety of oils and lubricants.

 

15.8 Site Buildings and Facilities

 

A plan of the site buildings and facilities is provided in Figure 15-1.

 

15.8.1 Operations and Maintenance Building

 

The Operations and Maintenance building is a masonry building that provides offices for Mine management, administration, and technical staff, including environmental, administrative management, training, accounting, safety, and security. It includes staff support facilities such as a conference room, printing room, and lunchroom.

 

The underground mine operations building, electrical room, trackless equipment workshop, tire shop, air compressor shop, maintenance shop, lamp house, lockers, and washrooms are constructed adjacent to the main entrance to the underground mine at a 50 m distance, as approved by Peruvian safety regulations.

 

To the south of the main entrance to the Mine are the main mine supplies storage, processing plant building, electrical workshop, backfill plant, and laboratory facilities.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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15.8.2 Accommodation Facilities

 

The permanent accommodation complex has been constructed on an approximately 60 ha site north of the Mine infrastructure complex. The accommodation complex incorporates the following camp sites:

 

Type A: staff houses, and staff hotel where dormitories are private, single occupancy rooms.

 

Type B: three story building blocks are semi-private and have single occupancy rooms with two rooms sharing one shower and a washroom.

 

Type C: three story blocks of dormitories are double occupancy rooms with a central shower and washroom facility shared by ten rooms.

 

The accommodation complex also includes the following facilities:

 

Kitchen, bakery, dining hall.

 

Recreation, exercise, and entertainment facility including a cinema that can also be used for meetings and training.

 

Three soccer fields.

 

Workers union building.

 

Hospital equipped with trauma treatment facilities as well as life support equipment. The hospital is comprised of a waiting and reception area, doctor’s office, operating theatre, two bed wards, washroom facilities, storage room, and ambulance parking.

 

15.8.3 Explosives Magazine

 

The explosives magazine has been constructed and operated in accordance with Peruvian Law.

 

15.8.4 Solid Waste Disposal and Recycling Facility

 

Non-recyclable, non-toxic solid waste is disposed of in an on-site lined landfill. Used tires are shredded and placed in the landfill.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Figure 15-1: Site Layout

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

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15.9 Tailings Storage

 

The El Porvenir TSF receives tailings generated by both El Porvenir and Atacocha concentrator plants. A portion of tailings is used for hydraulic backfill at El Porvenir. The El Porvenir TSF was originally constructed in the 1970s, and the current elevation of the dam crest is 4,060 MASL. The downstream toe is inferred to be less than 3,920 m from available plans, resulting in a dam height of 140 m.

 

Nexa is planning to improve the water management system through construction of a perimeter channel (i.e., upstream water diversion) to intercept clean (non-contact water) surface runoff water preventing its entrance to the TSF. Diverted water will be discharged downstream of the TSF in the Lloclla River gorge.

 

Contact water is recycled via a decant pumping system to the concentrator for use in the processing facility. The diversion on the western side of the TSF will be raised for the ultimate dam (Ausenco, 2016b). A lined seepage collection monitoring pond is located at the downstream toe of the main embankment to control water quality prior to water release to the environment. The monitoring pond is equipped with an overflow spillway and outlet channel for discharge into a local tributary creek of the Lloclla River.

 

A decant overflow system located on the left side of the main embankment conveys surplus flows from the tailings pond to the monitoring pond through the Lloclla Tunnel. Operation of a sluice gate at the pond location allows for the diversion of decanted water into the monitoring pond or bypass it, discharging directly into a local tributary creek of the Lloclla River. The water intake of the decant overflow system is a hydraulic structure consisting of two concrete towers with a series of inlets stacked vertically (referred to as “windows” in the Ausenco design reports). Inlets must be progressively blocked and rendered inactive as the deposited tailings reach certain elevation.

 

A channeling structure, consisting of two breakwaters, direct flows towards the emergency spillway. The spillway is an overflow tunnel located in the right abutment. It is reportedly designed to convey flows from probable maximum precipitation (SRK, 2017). The tunnel discharges via a tunnel daylighting at elevation 4,035 MASL. A lined seepage collection monitoring pond is located at the downstream toe of the main embankment.

 

The layout of the TSF with its crest elevation of 4,064 MASL is presented in Figure 15-2. The intention is to raise the main embankment in 10 m increments with intermediate raises of four metres. It is noted that the expansion of the TSF to contain the LOM tailings requires a rockfill embankment dam and seepage collection pond at the northeast corner of the TSF to prevent tailings from impacting the concentrator plant area, as well as the northwest where the Tingovado Creek is diverted. The embankment located at the process pond is raised progressively in a downstream direction and its upstream slope is lined with a two millimetre thick high density polyethylene (HDPE) geomembrane. The detailed design of the El Porvenir TSF to its final elevation of 4,100 MASL has been completed (Ausenco, 2016b). Planning is also currently underway to re-activate the Atacocha TSF and construction is underway to raise its embankment to an elevation 4,126 MASL (Ausenco, 2020). Upgrades to the pumping and piping systems at El Porvenir will allow disposal of the El Porvenir tailings, not used for hydraulic backfill, at the Atacocha TSF.

 

Figure 15-3 shows the main TSF dam with a crest elevation of 4,060 MASL in plan view. The average crest width is approximately 15 m, with an overall downstream fill slope of 2.5H:1V and 1.5H:1V upstream; with an average interbank slope of 2H:1V.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Figure 15-2: Tailings Storage Facility Layout with Dam at Elevation 4,064 MASL

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Figure 15-3: Tailings Storage Facility Main Dam Layout at Elevation 4,064 MASL

 

 

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Surface preparation for dam raises includes the removal of topsoil and unsuitable soils and compaction to provide a suitable foundation. For cases where there are cavities, a product of karst processes, the sealing of the openings with mortar or cyclopean concrete is required. To SLR’s knowledge the measures to address seepage through karst rocks have been implemented through recent TSF construction including a sandy gravel platform around the perimeter of the TSF (SRK, 2017), and bedrock foundation grouting of the dam abutments in 2015. On-going operations will require continuous tailings deposition planning and pond management to maintain the design beach widths to limit seepage through the permeable dam.

 

A cross section of the main dam at its ultimate crest elevation is shown on Figure 15-4. The initial TSF dam raises were performed using mainly compacted coarse tailings (cyclone underflow) with the centreline construction method. Due to a shortfall of the coarse fraction of the tailings to be used in the dam raises from 4,043 MASL, further raises used compacted rockfill and structural fill.

 

The crest of the dam is a horizontal platform of 15 m width and is composed of structural fill, which is mainly made up of sandy gravel. At the final elevation of the dam crest of 4,100 MASL, the height of the dam will be 187 m above the natural ground level of the gorge in which the dam is constructed.

 

In the design of the TSF, expansion plans considered that the processing rate would increase to 9,000 tpd in 2019 (3.24 Mtpa). Tailings produced would amount to 95.38% of ore processed. The design also considered the integration of El Porvenir with the Atacocha Mine and the disposal of Atacocha tailings in the El Porvenir TSF from 2016 onward. The Atacocha ore processing rate considered was 4,500 tpd (1.62 Mtpa) with plans for this to be increased to 5,000 tpd (1.8 Mtpa). Tailings produced would amount to 95% of ore processed.

 

Monthly and annual dam safety inspections are currently being conducted by Geoconsultoria Ltda, an external consultant, for both the Atacocha and El Porvenir dams. SLR relies on the conclusions of Geoconsultoria [latest annual report titled Evaluación Annual de Seguridad – 2018 dated March 20, 2019] and provides no conclusions or opinions regarding the stability of the listed dams and impoundments.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Figure 15-4: Tailings Storage Facility Main Dam Section to Elevation 4,100 MASL

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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15.10 Waste Rock Storage Facilities

 

Historically, the volume of waste rock deposited on surface has been minor given that the El Porvenir operation is an underground mine. In the past, waste rock has been deposited in two areas within the TSF, and La Quinua waste rock dump (WRD) located outside the TSF. The La Quinua WRD is currently inactive.

 

Currently, waste rock is only brought to surface for storage if backfilling is not possible. If waste rock is brought to surface in the future, it will be deposited in a designated area near the secondary TSF embankment (southwest of the concentrator plant area), approved in Directorial Resolution R.D. 693-2012 MEM-AAM/LCD/RPP/MPC.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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16.0 Market Studies

 

16.1 Markets

 

The principal commodities produced at El Porvenir, zinc, lead, copper, and silver, are freely traded, at prices and terms that are widely known, so that prospects for sale of any Nexa production are virtually assured. El Porvenir is an operating mine with concentrate sales contracts in place for copper and lead concentrates, while zinc concentrate is consumed by Nexa’s Cajamarquilla smelter according to their internal planning. SLR has reviewed the concentrate terms provided by Nexa and found them to be consistent with current industry norms.

 

Market information in this section is based on the industry scenario analysis prepared by Nexa’s Market Intelligence team in July 2020 based on information sourced from different banks and independent financial institutions, economy and politics research groups, and metals consultants.

 

Nexa’s Market Intelligence team notes that the industry has progressed from volatile markets in 2019 due to US/China trade wars, Brexit, and developing economies slowing down, to more uncertainty in 2020 due to the COVID-19 pandemic, a plunging global economy, the oil crisis, and the US elections. All these factors have affected the market fundamentals.

 

The SLR QP has reviewed the market studies and analyses and is of the opinion that the results support the assumptions in the Technical Report Summary.

 

16.1.1 Zinc

 

16.1.1.1 Demand

 

The major market drivers for zinc demand are construction and infrastructure, transportation and vehicles production, industrial machinery production, batteries, and renewable energy. All these industries have been affected by the COVID-19 pandemic which has caused the global economy to slow down. As a result, zinc metal demand has also decreased in 2020, by approximately 10% year over year.

 

Nexa’s Market Intelligence team examined several scenarios for demand recovery and future growth and settled on a base case that forecasts pre-COVID-19 levels of demand in the second half of 2022, with a demand compound annual growth rate (CAGR) of approximately 1.3% from 2023 to 2025. In 2019, they had forecasted a CAGR of approximately 1.7% between 2019 and 2024.

 

16.1.1.2 Supply

 

Nexa’s Market Intelligence team’s supply forecast analysis was based on the following industry information: zinc mine start-up and closure, mine production guidance, disruption allowance evaluation, project pipeline, and cost evaluation for 2020 onwards. Nexa’s forecast analysis results are summarized as follows:

 

Mine disruption factor: Based on independent data, Nexa has forecast a mine disruption factor of 4% for China and 4% until 2023 and 2% to 3% for 2024 and 2025 for the rest of the world (ROW).

 

Project Pipeline: The analysis considered greenfield projects forecast to begin production between 2020 and 2025.

 

 

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Zinc concentrate production evolution - Global: Recent market conditions due to the COVID-19 pandemic have affected mines worldwide, reducing investments and causing mine closures. As a result, zinc supply might be limited in the long term.

 

China concentrate evolution: China concentrate supply is expected to increase by 3% through the 2020 to 2025 cycle, but significantly depends on the ability of China’s small mines to survive amid lower price levels and volatile market conditions.

 

Zinc Global Market Balance: Based on the above considerations, Nexa’s forecast is for a significant zinc supply surplus in 2020 and 2021, with an increase in demand starting in the second half of 2022. From 2024 onwards, the global demand will exceed zinc supply.

 

16.1.1.3 Zinc Price Outlook

 

Zinc prices depend on variations in supply, demand, and the perceived supply/demand balance. The most commonly referenced currency for zinc transactions is US dollars. Based on Nexa’s Market Intelligence team’s analysis of zinc supply, demand, global balance, and zinc consensus prices, Nexa forecasts stressed zinc prices in 2021 and 2022 as between $2,000/t and $2,300/t, with a potential price increase to greater than $2,700/t starting in 2024 to 2025, and a long term price of $2,449/t. Figure 16-1 shows the results of Nexa’s analysis.

 

 

Source: Nexa, 2020f

 

Figure 16-1: Zinc Price Outlook (2020-2025)

 

16.1.2 Copper

 

16.1.2.1 Demand

 

The major market drivers for copper demand are power generation and transmission, construction, factory equipment, and the electronics industry. The COVID-19 pandemic affected copper demand in 2020 and, in the opinion of Nexa’s Market Intelligence team, will also impact it in the years ahead (2021 and 2022). In the long term, the Nexa predicts a lower demand growth, mainly reflecting China’s economic transition, despite the positive contribution of global trends such as electric vehicles, renewable energy, and urbanization.

 

 

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Nexa analyzed multiple demand scenarios, with a Base Case forecasting a reduction in copper demand by 9.0% between 2019 and 2020, and starting in the second half of 2020, a slower paced recovery with a demand CAGR of 3.2% between 2020 and 2025. Copper demand is predicted to grow from 26.9 Mt in 2020 to 31.5 Mt by 2025.

 

16.1.2.2 Supply

 

Nexa’s Market Intelligence team’s supply forecast analysis was based on the following industry information: copper mine start-up and closure, mine production guidance, project pipeline, and cost evaluation for 2020 onwards. Nexa’s forecast analysis results are summarized as follows:

 

Project Pipeline: The pipeline is short, mainly because there are fewer opportunities in mining friendly jurisdictions.

 

Copper concentrate (sulphide) production evolution: Nexa considers that the majority of the production will come from sulphide mines. Nexa forecasts a concentrate production CAGR increase of 4.2% between 2020 and 2025. The increase in supply results from the ramp-up of brownfield projects.

 

Copper solvent extraction and electrowinning (SXEW) (oxide) production evolution: Nexa forecasts a downward trend for SXEW production. Based on Nexa’s analysis, a concentrate production CAGR will decrease by 2.7% between 2020 and 2025, as a result of mine closures and reductions in production.

 

Refined Copper Market Balance: the copper market has been in deficit for the last three years, leading to lower stocks, despite lower prices since mid-2018 mainly due to the trade war between the USA and China, and the COVID-19 pandemic outbreak in 2020. Based on the above production assumptions, Nexa provided a forecast for Copper Market Balance between 2020 and 2025, showing a significant copper supply surplus in 2020 and a slightly positive surplus in 2021 and 2022. From 2023 onwards, the global copper demand will create a deficit in copper supply (Figure 16-2).

 

 

Source: Nexa, 2020f

 

Figure 16-2: Refined Copper Market Balance (2020-2025)

 

 

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16.1.2.3 Copper Price Outlook

 

Copper prices depend on variations in supply, demand, and the perceived supply/demand balance. Based on Nexa’s Market Intelligence team’s analysis of copper supply, demand, global balance, and copper consensus prices, Nexa forecasts stressed copper prices between 2021 and 2024 as between $6,040/t and $6,351/t, with a potential price increase to higher than $6,500/t after 2024, and a long term price of $6,627/t. Figure 16-3 shows the results of Nexa’s analysis.

 

 

Source: Nexa, 2020f

 

Figure 16-3: Copper Price Outlook (2020-2025)

 

16.2 Contracts

 

16.2.1 Streaming Agreement

 

There are no streaming agreements associated with El Porvenir.

 

16.2.2 Other Contracts

 

Various operational support services are provided by contractors, including underground mining, surface tailings haulage and placement, concentrate haulage, catering, security, and the Mine site laboratory.

 

There are currently 1,794 contractor personnel providing the services as listed in Table 16-1.

 

Table 16-1: Third Party Contractors

Nexa Resources S.A. - El Porvenir Mine

 

Contractor   Area   Personnel
A&G Ced S.A.C.   Human Resources   15
Ancro S.R.L.   Environment   6
Antares Mantenimiento Industrial S.A.C.   Plant   17

 

 

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Contractor   Area   Personnel
Ausenco   Projects   2
Biddle Inc S.A.C.   Plant   9
    Mine   61
Confipetrol Andina S.A.   Plant   145
Constructora Pawer S.R.L.   Health & Safety   3
Corporacion Zafiro Sdj E.I.R.L.   Mine   4
Distribuidora De Mangueras Hidraulicas Sac   Mine   5
Explomin Del Peru S.A. Exploración   Mine   65
Explomin Del Peru S.A. Infill   Mine   62
Exsa S.A.   Mine   56
Ferreyros S.A.   Mine   15
Grupo Alvarado   Information Technology   1
Iesa S.A.   Mine   548
Incimmet S.A.   Mine   24
Inspectorate Services Peru S.A.C.   Plant   19
    Mine   155
Operaciones Seprocal S.A.C   Mine   67
Prosegur   Human Resources   50
Resiter Peru S.A.C.   Mine   6
Salus Laboris S.A.C.   Health & Safety   26
Sandvik Del Peru S.A.   Mine   55
    Human Resources   101
Esermul   Human Resources   13
Sodexo   Human Resources   111
Steo   Health & Safety   8
Transportes Brandito   Environment   5
Transportes Expreso Milpo S R Ltda   Human Resources   12
Tumi Contratistas Mineros S.A.C.   Mine   14
Union De Concreteras S.A.   Mine   114
Total       1,794

 

SLR has reviewed the mine operating costs related to contracts and found these to be reasonable, as long as the production targets are realized.

 

 

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16.2.3 Quality of Zinc Concentrate

 

Table 16-2 presents the average quality of the zinc concentrate El Porvenir shipped to the Cajamarquilla smelter in 2019. El Porvenir’s concentrate made up to approximately 5% of the smelter’s feed in 2019.

 

Table 16-2: Quality of El Porvenir Zinc Concentrate

Nexa Resources S.A. – El Porvenir Mine

 

Zn
(%)
  Cu
(%)
  Fe
(%)
  Pb
(%)
  S
(%)
  CaO
(%)
  MgO
(%)
  Hg
(ppm)
  Moisture
(%)
49.9   1.0   8.1   1.3   32.1   1.2   0.5   7.0   8.0

 

Source: Nexa 2020d

 

16.2.4 Concentrate Sales Contracts

 

El Porvenir has contracts for the sale of its copper and lead concentrates with refineries and global traders. Nexa considers these contracts to be in line with industry norms. El Porvenir ships its zinc concentrate to smelters owned by Nexa.

 

16.2.5 Penalties

 

Table 16-3 and Table 16-4 present the schedules of the contaminant element penalties for El Porvenir’s lead and copper concentrates, respectively. While no penalties are currently applied to the zinc or lead concentrates, the copper concentrate incurs a penalty of approximately US$17/dmt.

 

Table 16-3: Contaminant Element Penalties - Lead Concentrate

Nexa Resources S.A. – El Porvenir Mine

 

As: between $1 and $2 for each 0.1%, when grade is be higher than 0.5%.
Sb: between $1 and $2 for each 0.1%, when grade is be higher than 0.5%.
Bi: between $1 and $1.5 for each 0.01%, when grade is be higher than 0.6% or 1.1% (typically 1.1%)
Mn: There may be penalty scales above 10%, values between $1-$2 for each 0.1%
Pb: when grade is below specification (normally <45%).

 

Table 16-4: Contaminant Element Penalties - Copper Concentrate

Nexa Resources S.A. – El Porvenir Mine

 

As: $1.5 for each 0.1% above 0.3%
Sb: $5-$6 for each 0.1% above 0.3%
Bi: $1.5 for each 0.01% above 0.06%
Pb+Zn: $1.5 for each 1% above 9% (this penalty can be separate Pb and Zn, as well)

 

16.2.6 Concentrate Specifications

 

The lead concentrate contains, on average, 50% Pb and 2,500 g/t Ag. The copper concentrate contains, on average, 20% Cu and 2,500 g/t Ag.

 

 

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17.0 Environmental Studies, Permitting, and Plans, Negotiations, or Agreements with Local Individuals or Groups

 

The information presented in this section is based on documentation provided by Nexa for review. No site visit was conducted in support of the preparation of Section 17 of this Technical Report Summary.

 

17.1 Environmental Aspects

 

17.1.1 Mine Operation Overview

 

El Porvenir is located in the district of San Francisco de Asís de Yarusyacán, in the province of Pasco, Peru, approximately 13 km northeast of the town of Cerro de Pasco. The property is in the central Andes mountains region of Peru, between elevations 3,900 MASL and 4,350 MASL. The El Porvenir LOM currently extends until 2027.

 

The El Porvenir facilities are located within the micro-basin of the Milpo Creek, which discharges to the Chinchao Creek and this in turn to the Lloclla River. The Lloclla River is formed by the confluence of the Pucayacu and Jabonera creeks, and flows into the Panamarca River, which becomes the Huallaga River further downstream. Consequently, the El Porvenir area belongs to the water system of the upper basin of the Huallaga River (i.e. the Alto Huallaga Inter-basin). Highest flows in the Lloclla River typically occur in March, with lowest flows in July.

 

The El Porvenir operation is comprised of the following main facilities:

 

Underground mine

 

Concentrator plant

 

TSF

 

WRDs (currently inactive)

 

Water management facilities and infrastructure

 

Ancillary buildings and infrastructure (administration, storage, vehicle maintenance, domestic waste landfill, waste management, etc.)

 

With the integration of the Atacocha and El Porvenir operations, tailings from Atacocha are deposited in El Porvenir TSF, located approximately four kilometres south of Atacocha. This is the current tailings disposal practice.

 

El Porvenir operates a conventional concentration processing plant with a nominal capacity of 6,500 tpd of ore. The concentrator plant processes on average approximately 5,800 tpd to 5,900 tpd. The processing flowsheet includes a multistage crushing plant, a conventional ball mill grinding stage, and sequential differential flotation to produce three final mineral concentrates: a zinc concentrate, a lead concentrate, and a copper concentrate (SRK, 2017). Power supply is obtained from the national grid through a 138 KV power line.

 

Environmentally, El Porvenir is not located within a protected natural area nor its buffer zones (SRK, 2017).

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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17.1.2 Environmental Baseline

 

Environmental baseline studies have been completed as part of the EIA. The detailed baseline characterization is included in the EIA reports. A summary of the existing conditions in the El Porvenir area based on information included in Ecotec (2018) and KCB (2020) is presented below.

 

17.1.2.1 Climate

 

The climate is cold and dry throughout the year, which is typical of the Central Andes Mountain Region. Approximately 80% of the annual rainfall takes place between October and March. From June to August there are generally minimal rainfalls. Based on data from the Cerro de Pasco regional meteorological station operated by the government (data record from 1975 to 2017), the average temperature ranges from 4°C in July to 6°C in November. The average annual precipitation is 943 mm, with maximum monthly precipitation of 135 mm in March and minimum monthly precipitation of 15 mm in July.

 

17.1.2.2 Air Quality

 

Air quality has been characterized using records from eight monitoring stations for the period 2016 to 2018. The monitoring results are compared against national environmental quality standards for air quality (D.S. No. 003-2017-MINAM). Measured concentrations for particulate matter less than 10 μm (PM10), particulate matter less than 2.5 μm (PM2.5), gases (sulphur dioxide, nitrogen dioxide, carbon monoxide, ozone, hydrogen sulphide) and benzene were below the limit set in the standard.

 

17.1.2.3 Surface Water Quality

 

Characterization of existing conditions presented in Ecotec (2018) and KCB (2020) is based on surface water quality monitoring conducted at five sampling locations in three natural waterbodies (Lloclla River, Tingovado Creek, and Huallaga River). Four of these stations are located upstream of the mining activities and one is located downstream. Surface water quality is compared with the national environmental quality standards for water: D.S. No. 002-2008-MINAM for monitoring records from 2013 and 2014, D.S. No. 015-2015-MINAM for monitoring records from 2015 and 2016, and D.S. No. 004-2017-MINAM for monitoring records from 2017 and 2018. The reference values selected from the standards correspond to class 3-D1 for irrigation of high and low stem crops, and class 4-E2 for the Huallaga River.

 

Results from monitoring of water quality in the Lloclla and Huallaga rivers indicate a reduction of exceedances over time. Monitoring data from 2016 to 2018 (Ecotec, 2018)indicate some exceedances associated with zinc and lead in the Huallaga River, and some exceedances for pH, lead and manganese in the Lloclla River.

 

The water quality analysis included in Ecotec (2018) presented an individual discussion for each parameter explaining how the exceedances are associated with geological and morphological conditions inherent to the El Porvenir location. From the data presented in the Ecotec report exceedances are observed for short periods of time and are not simultaneously occurring for all the monitored parameters.

 

17.1.2.4 Effluent Water Quality

 

Effluent water quality is monitored at two discharge locations: water discharge from the underground mine to the Huallaga River, and water discharge from the TSF to the Lloclla River. The water quality at the effluent discharge locations complies with the maximum permissible limits established by the current Peruvian Legislation (D.S. No. 010-2010-MINAM and D.S. 003-2010-MINAM).

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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17.1.2.5 Groundwater Quality

 

No groundwater quality monitoring has been carried out prior to 2020 with the exception of monitoring at two locations where discharge of groundwater to surface from the aquifer takes place (i.e. springs). According to Ecotec (2018), one of the springs (station 13MM) has the potential to influence concentrations of arsenic, manganese, and lead in the waters of the Lloclla and Huallaga rivers. The second spring (station 14MM) has the potential to influence concentrations of arsenic in the water of the Lloclla and Huallaga rivers. Comparison against national standards is not applicable because no standards for groundwater quality have been developed for Peru.

 

17.1.2.6 Soils and Land Use

 

There are two types of soils in the El Porvenir area, mineral and organic, derived from residual and transported soils. Actual land use corresponds to five categories: urban development (populated centers) and private facilities (mining activity), cultivated land, natural pastures, arboreal vegetation, and unproductive land (rock outcrops).

 

Soils at El Porvenir have concentrations of arsenic, cadmium, and lead that exceed the national environmental quality standards (D.S. No. 011-2017-MINAM for industrial use), at some sampling points. According to the baseline characterization, high values of arsenic and lead could be attributed to the local lithology and mineralization. High values of cadmium could be of natural origin since cadmium is associated with zinc and lead impurities.

 

17.1.2.7 Noise and Vibrations

 

Ambient noise has been characterized using records from eight monitoring stations for the period 2016 to 2018. Exceedances were registered in three stations during the day and four stations at night when comparing the monitoring results against the national environmental noise quality standards (D.S. No. 085-2003-PCM) for an Industrial Zone. Exceedances were attributed to human activities and vehicular traffic (Ecotec, 2018). The ambient vibrations monitored at three locations meet international standards used as a reference (BS7385 Part 2-1993).

 

17.1.2.8 Aquatic Biology

 

Aquatic communities account for plankton, periphyton, macroinvertebrates (benthos), and fish. According to KCB (2020), during the wet season in 2015 the phytoplankton was represented by 56 species, the zooplankton by 16 species, the periphyton by 45 species, the benthos by 30 species, and the fish by one specie (Oncorhynchus mykiss [rainbow trout]). During the wet season in 2016 the phytoplankton was represented by 27 species, zooplankton by nine species, periphyton by 11 species, and benthos by 14 species. None of the species identified in the El Porvenir area of influence are included in the list of protected species within the Peruvian legislation.

 

17.1.2.9 Flora

 

There are five species included in the national protection list approved under Supreme Decree D.S. No. 043-2006-AG that are found in the El Porvenir area: Ephedra rupestris (CR), Senecio nivalis (VU), Chuquiraga spinosa (NT), Baccharis genistelloides (NT), and Buddleja coriácea (CR). One specie was identified as endemic: Plantago serícea (Plantaginaceae), and two species are used for medicinal purposes by local communities: Minthostachys mollis and Ephedra rupestris.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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17.1.2.10 Fauna

 

Fauna in the El Porvenir area is represented by six species of mammals, 34 species of birds, one specie of amphibian, and one specie of reptiles. Four species of mammals, eight species of birds, one specie of amphibian, and one specie of reptiles are included in the national protection list approved under Supreme Decree D.S. No. 004-2014-MINAGRI. The endemic species include two species of mammals, two species of birds, one specie of amphibian, and one specie of reptiles.

 

17.1.2.11 Fragile Ecosystems

 

The high elevation wetlands (bofedales in Spanish) are present within the area of indirect influence of El Porvenir (i.e. they are located outside the direct area of influence). Ecosystems considered as fragile in Perú are recognized by Law No. 28611 – Environment General Law.

 

17.1.2.12 Social

 

The El Porvenir area of influence encompasses the following rural communities and populated centers (list provided by Nexa through email communication):

 

Comunidad de San Francisco de Asís de Yarusyacán (20 Anexos),

 

Comunidad de Titaclayán,

 

Comunidad de Cajamarquilla,

 

Comunidad de Malauchaca,

 

Comunidad Santa Rosa de Pitic,

 

Comunidad San Miguel,

 

Comunidad La Candelaria,

 

Centro Poblado La Quinua,

 

Comunidad 30 de Agosto,

 

Comunidad San Juan de Yanacachi,

 

Comunidad San Juan de Jarapampa, and

 

Cooperativa Pucayacu.

 

17.1.3 Environmental Studies and Key Environmental Issues

 

SLR has been provided with the following documents and reports to conduct its review:

 

Modification of the Environmental Impact Assessment for Capacity Expansion of the Concentrator Plant to 5,500 tpd (Compañía Minera Milpo, 2011)

 

Modification of the Environmental Impact Assessment for Capacity Expansion to 7,500 tpd (Cesel Ingenieros, 2011)

 

Fifth Supporting Technical Report (Quinto Informe Técnico Sustentatorio) for Modification of Auxiliary Components of El Porvenir Mine (Ecotec, 2018)

 

Sixth Supporting Technical Report (Sexto Informe Técnico Sustentatorio) for Introduction of Technical Improvements to the Concentrator Plant (Escegis S.R.L, 2020)

 

List of approved permits for El Porvenir (updated list provided on November 17, 2020)

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Annual Report on Compliance with the Environmental Management Strategy in 2018 (Nexa, 2019)

 

Annual Report on Compliance with the Environmental Management Strategy in 2019 (Nexa, 2020e)

 

Quarterly monitoring reports on surface water quality, effluent discharge quality, air quality, non-ionizing radiation, noise and domestic wastewater treatment prepared by SGS del Perú for Nexa in 2019 and 2020

 

Bi-annual monitoring reports on terrestrial and aquatic biology (fauna and flora) campaigns carried out in 2019 prepared by RYG Consultora Ambiental for Nexa

 

Reports from SGS Perú for 2020 on groundwater quality analysis for samples taken near the TSF dam

 

Emergency response plan for El Porvenir (document No. MU-EP-SSM-SSO-003-ES Rev. 1 from 2020)

 

Independent Technical Report pursuant to National Instrument 43-101 of the Canadian Securities Administrators for El Porvenir Mine, Perú. Report prepared by SRK Consulting issued on August 15, 2017

 

El Porvenir is managed according to the environmental and closure considerations presented in four type of documents, which must be approved by directorial resolutions (RD for its acronym in Spanish) from the Peruvian government (see Project Permitting):

 

Environmental Adjustment and Management Plan

 

EIA and subsequent modifications

 

Supporting Technical Reports (ITS for its acronym in Spanish)

 

Mine Closure Plan

 

Various EIA modifications and ITSs have been submitted and approved between 2001 and 2020. The most recent EIA approved in 2012 corresponds to the expansion of the concentrator plant production rate to 7,500 tpd.

 

The key project effects and associated management strategies are presented in Table 17-1, as described in the EIA and ITS documents reviewed by SLR. Prevention and mitigation measures identified for soils, air quality, water quality, biology, socio-economic aspects, landscape, and archeological remains are presented in the Environmental Management Plans included in the EIA and ITS documents. Mitigation measures against vibrations are not considered in the environmental studies provided to SLR. The monitoring program includes meteorology, air quality, non-ionizing radiation, noise, surface water quality, spring water quality, effluent discharges, flora and fauna, and TSF physical stability. In the SLR QP’s opinion, the Environmental Management Plan is adequate to address potential issues related to environmental compliance.

 

Air quality and ambient noise monitoring are currently conducted at six locations, while monitoring of non-ionizing radiation is conducted at two locations. Water quality monitoring is currently occurring at a total of 14 locations (see Table 17-2). The results of the monitoring program for these environmental aspects are reported to the Peruvian authorities quarterly.

 

No environmental issues that could materially impact the ability to extract the Mineral Resources and Mineral Reserves were identified by SLR from the documentation available for review.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Table 17-1: Summary of Key Environmental Effects and Management Strategies

Nexa Resources S.A. – El Porvenir Mine

 

Environmental
Component
  Potential Impact   Mitigation Measures / Management Strategies
Topography and landscape   Relief alteration changes in landscape’s visual quality.   No specific measures or strategies are proposed.
Soils   Changes to soil uses.
Changes to soil quality.
  Mitigation measures imbedded in the infrastructure design to minimize spill accidents.
Appropriate management of industrial and domestic waste.
Appropriate management of oils and fuels.
Appropriate management of hazardous waste.
Development and implementation of spills management plan.
Removal of soils exposed to spills and storage in sealed containers for appropriate disposal in agreement with applicable legislation.
Activities for vehicle maintenance are restricted to designated areas.
Surface water   Changes to surface water flows.
Changes to surface water quality.
  Appropriate management of chemical substances.
Development and implementation of spills management plan.
Domestic wastewater treatment.
Mine water sedimentation ponds.
Diversion of non-contact water around the TSF.
Inspection and maintenance of the TSF diversion channel.
Collection of surface runoff in the concentrator plant area.
Sediment and erosion control measures.
Tailings sub-drainage is captured in a monitoring pond and recirculated or discharged according to its quality, considering sediment control.
Monthly water quality monitoring for receiving water bodies and effluent discharges.  Currently Nexa reports monitoring results from 11 stations (five of them are effluent discharges).
Quarterly reporting of monitoring results.
Groundwater   Changes to phreatic level.
Changes to groundwater quality.
  No specific measures or strategies are proposed.
Monthly water quality monitoring in two springs and one piezometer (see Table 17-2).
Quarterly reporting of monitoring results.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Environmental
Component
  Potential Impact   Mitigation Measures / Management Strategies
Air quality   Changes from particulate and gas emissions.   Regular irrigation of access roads with tanker trucks during the dry season.
Wet grinding.
Traffic speed control.
Regular preventive maintenance of vehicles and equipment.
Use of personal protective equipment by mine staff and training.
Monitoring of particulate matter (PM10 and PM2.5), metals (lead, arsenic and zinc) and gases during the construction and operation phases.
Monthly air quality monitoring at six stations located leeward and windward of the Concentrator Plant and the TSF.
Quarterly reporting of monitoring results.
Noise   Disturbances resulting from changes
to ambient noise levels.
  Use of hearing protection devices in the concentrator plant area.
Controlled time of exposition of workers to noise sources.
Appropriate planning and scheduling of operation of noise sources.
Regular preventive maintenance of vehicles and equipment.
Use of vehicle horns limited to emergency situations.
Quarterly monitoring at six stations.
Quarterly reporting of monitoring results.
Flora and fauna   Changes to vegetation cover.
Alterations to habitat.
Disturbance of wild fauna.
  Prohibition to disturb fauna.
Land clearing limited to authorized areas.
Prohibition to collect flora.
Prohibition to extract species of flora and fauna.
Noise control measures.
Sediment control measures to protect natural streams.
Traffic speed limits.
Prohibition to use vehicle horns except in case of emergency.
Monitoring of phytoplankton, zooplankton, benthic organisms, perifiton and macrofitas at four stations.
Monitoring of metals content in sediment samples.
Monitoring of flora at four stations.
Monitoring of fauna at four stations.
Bi-annual monitoring (dry and wet season).

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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17.1.4 Environmental Management System

 

Nexa uses an ISO 14001 compliant environmental management system at El Porvenir to support environmental management, monitoring and compliance with applicable regulatory requirements during operation.

 

Nexa utilizes an Integrated Dam Management System (referred to as SIGBar) for the TSF, which provides guidelines for document management, monitoring, evaluation, risk analysis, compliance with standards and legislation, training of personnel, operation of structures and other provisions.

 

The environmental monitoring program established at El Porvenir and the environmental audits performed annually (aiming to identify critical environmental risks in the operations) are the main tools of the El Porvenir’s Environmental Management System to track the implementation of high environmental standards and the continuous compliance with the environmental commitments. The environmental audit matrix includes the evaluation of:

 

Audit results to comply with legal requirement for environmental audit.

 

Environmental monitoring activities.

 

Environmental incidents.

 

Nexa does not have an Environmental Policy for El Porvenir. According to Nexa’s website and the Nexa Annual Report on 2019 performance, the company identifies and manages the main risks from both an operational and strategic point of view, reducing and mitigating impacts to maintain business sustainability. Nexa has an integrated management system that establishes the guidelines that govern the conduct of the businesses, with a focus on quality management of environmental, health and workplace safety, and social responsibility issues. In addition, Nexa follows applicable environmental laws and regulations pertaining to its business in each country where it operates (Nexa, 2019).

 

Nexa has stated the following environmental goals in its Annual Report on 2019 performance:

 

75% recirculation and lower specific use of water.

 

Reduce the specific emission of greenhouse gases by 5%.

 

Decrease the disposal of tailings in dams and a 50% reduction in the specific generation of mining and smelting waste.

 

Ensure that 100% of the units have pre-prepared future use alternative studies and updated decommissioning plans, in line with the sector’s benchmark standards.

 

17.2 Mine Waste and Water Management

 

17.2.1 Environmental Geochemistry

 

Geochemical testing of the cyclone tailings underflow by Ausenco (2013) determined that the tailings have a high potential for generating acid drainage in the long term. While the leaching tests do not indicate potential for metal solubilization in the short term, kinetic tests, that demonstrate the evolution of the quality of the leachates over time, have not been completed. Geochemical testing by the Universidad Nacional de Ingenieria (Ausenco 2018) of the waste rock used for dam construction concluded that the rock was non-acid generating.

 

According to information included in the initial Mine Closure Plan (KCB, 2007), the waste rock deposited on surface (mostly in the La Quinua WRD) is non-acid generating. No geochemistry analysis of the rock walls of the El Porvenir underground mine has been conducted. If the rock is similar to the material disposed in the La Quinua WRD, then it is either non-acid generating or has an uncertain potential for acid generation. Due to high neutralization potential of the rock identified from early testing, no acid rock drainage (ARD) is anticipated to occur in the short or mid term. The Mine Closure Plan recommends carrying out additional geochemical studies to confirm the rock acid generation potential before closure in order to define and appropriate closure strategy and management measures to achieve geochemical stability.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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17.2.2 Tailings Management

 

The safety of operating a centerline raised tailings dam depends on the ability to maintain wide tailings beaches and a low phreatic level in the dam shell for stability. SLR notes that no water balance information was available for review regarding the interaction between the Atacocha and El Porvenir operations, which is significant since the El Porvenir milling operations draws reclaim water from the TSF. The SLR QP is of the opinion that impact of a temporary suspension of El Porvenir milling operations on the El Porvenir TSF water balance should be considered.

 

Crest settlements at the left side of the dam were reportedly noted in a 2008 report by Golder Associates that was not available for review (SRK, 2017). No issues with regard to crest settlements were noted in recent dam safety monitoring reports. SLR notes however that bedrock foundation grouting of the left and right abutments carried out in 2015 observed very significant grout takes in numerous grouthole stages indicating the filling of voids. A series of seepage collection sub-drainage pipes were also installed on the downstream shell of the dam prior to raising the rockfill to the crest elevation of 4,056 MASL (Ausenco, 2016a).

 

Tailings disposal at El Porvenir is performed in subaerial conditions which allows a beach with a gentle slope towards the water or supernatant pond (settling pond). Tailings deposition planning considers deposition from three main locations. These discharge locations allow for the settling pond to be centrally located within the TSF and a tailings beach to form in front of the main embankment. The minimum beach width is 150 m. A capacity assessment of the TSF by Nexa (2020) recommends topographic and bathymetric surveys every six months to assess the available capacity.

 

Dam monitoring at El Porvenir consists of instrument measurements and field inspections. Field inspections (regular routine inspections) are carried out by Nexa personnel responsible for its operation, and monthly by an external consultant (Geoconsultoria). Piezometers and water level indicators are measured every two weeks, surface landmarks monthly, pluviometry, the graduated level of the water level within the TSF, is read daily. The data is reviewed by an external consultant (Geoconsultoria) on a monthly basis. An annual audit report is also completed by Geoconsultoria. Nexa utilizes an Integrated Dam Management System (referred to as SIGBar) which provides guidelines for document management, monitoring, evaluation, risk analysis, compliance with standards and legislation, training of personnel, operation of structures and other provisions.

 

The latest monthly inspection report by Geoconsultoria, reviewed by SLR was dated 28 April 2020. Geoconsultora (2020) stated that the freeboard and upstream beach width were acceptable, however the emergency spillway channel was covered during the construction of the non-contact diversion ditch, and some damage to a survey monument required repair (the survey monument has been repaired). The last annual audit report by Geoconsultoria reviewed by SLR was dated March 2019. The report concluded that the safety condition of the tailings dam is satisfactory.

 

 

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The following recommendations are proposed for the El Porvenir TSF:

 

Classification of the TSF in terms of the Global Tailings Standard or the Canadian Dam Association. The classification may require more conservative design criteria in terms of flood management and seismic loading.

 

A dam breach analysis to inform the TSF classification and emergency preparedness plan.

 

A trigger alert response plan (TARP) for the piezometers for inclusion in the monitoring plan.

 

Capacity assessments of the TSF completed on a bi-annual basis with topographic and bathymetric surveys.

 

Complete long term geochemical kinetic testing of the tailings.

 

Implement a groundwater monitoring program at the TSF to determine levels of metals and sulphates.

 

Monitor the water quality from the TSF subsurface drains.

 

17.2.3 Water Management

 

Freshwater is withdrawn at the Yanamachay pumping station from the Carmen Chico River and the Huarmipuquio Spring for distribution to the potable water tank and three water supply ponds that feed the concentrator plant for industrial processes. These water supply ponds also receive water from the Milpo Creek via the Socorro Pond. Water from the potable water tank is supplied to the mine camp and neighbouring communities (Vista Alegre, San Carlos, San Juan).

 

Water for underground mine operations activities is taken from the water supply ponds of the concentrator plant. Underground mine water is pumped to the La Quinua Sedimentation Pond to promote settling of solid particles before being discharged to the Huallaga River.

 

Tailings discharged to the TSF come from the El Porvenir and Atacocha concentrator plants. Tailings water and surface runoff resulting from direct rainfall over the TSF footprint are collected in the tailings pond. Water from the tailings pond is recirculated to the El Porvenir concentrator plant as make-up water for ore processing via the three water supply ponds of the concentrator plant area. Seepage water intercepted by the TSF underdrain system is captured in a lined monitoring pond and recirculated to the tailings pond or discharged into a local tributary of the Lloclla River if the water quality meets the applicable standards for direct discharge to the environment. Surplus water collected in the TSF pond is discharged through a decant overflow system that conveys flows to the monitoring pond. Operation of a sluice gate at that location allows for discharge control of decanted water into the monitoring pond or directly into a local tributary of the Lloclla River. As a contingency measure, the water management system allows conveyance of water collected in the monitoring pond to the sediment ponds located near the La Quinua WRD.

 

Nexa is planning to improve the TSF water management system through construction of a perimeter channel to intercept non-contact water (freshwater) from the sub-watershed that contributes natural surface runoff towards the TSF footprint. The Chinchao and Tingovado creeks will be intercepted by this diversion channel that will redirect water from the creeks towards the Lloclla River.

 

Sanitary wastewater generated at El Porvenir is collected and treated in a wastewater treatment plant. Treated water is conveyed to the tailings pond of the TSF for re-use in mine operation activities.

 

SLR did not find evidence of an integrated site-wide water balance for the El Porvenir and Atacocha operations within the documentation provided for review. Furthermore, it is unclear if the water balance for El Porvenir is continuously tracked during operation to support decision making associated with water management and dam safety. A water balance for ongoing operations to be updated regularly by mine operations personnel (or a designated consultant) is an important tool to ensure that sufficient water is available for ore processing and that pond water levels are adequate for safe operation of the TSF. The water balance makes it possible to track trends and conduct short term predictions through the simulation of variable operating and/or climatic scenarios to support decision making associated with tailings pond operation (e.g., maintaining adequate dam freeboard at all times).

 

 

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SLR recommends Nexa develop an integrated water balance that reflects the interaction between the El Porvenir and Atacocha operations in regard to water balance, to identify and predict possible scenarios of interruption of mine operations due to water management issues and/or dam safety concerns (e.g., not maintaining adequate dam freeboard).

 

According to the Nexa 2020 Annual Report on Compliance with the Environmental Management Strategy in 2019, water quality monitoring currently takes place at the 14 locations listed in Table 17-2. Based on the documentation available for review, SLR is not aware of any non-compliance issues raised by the authorities associated with the El Porvenir water quality monitoring program.

 

Based on the Environmental Management Plans presented in the EIA and ITS documents, only one groundwater quality monitoring location is included in the environmental monitoring program. Monitoring results at this location are not included in the quarterly monitoring reports on water quality. SLR was provided with 11 reports from SGS, a laboratory accredited by the Peruvian authorities, with results of water quality analysis of samples taken between January 2020 and November 2020 at location PH-1 identified as “TSF dam”. Each report covers a period of data of approximately one week. No interpretation of analysis results is included in these reports.

 

Typical practice for environmental monitoring of groundwater involves the installation of wells upstream and downstream of the mine site to compare water quality results and identify potential impacts of the mine operation to groundwater. It is unclear how El Porvenir currently verifies that no changes to groundwater due to mining activities are taking place within the area of influence of the operation. SLR recommends expanding the groundwater quality monitoring program to include additional stations for collection of groundwater quality samples (and subsequent analysis). As a minimum, consideration should be given to the installation of one station upstream of El Porvenir.

 

Table 17-2: Water Quality Monitoring Locations

Nexa Resources S.A. – El Porvenir Mine

 

Station ID   Type of Water   Location
5MM   Surface water effluent   Underground mine discharge at La Quinua tunnel outlet.
5AMM   Surface water effluent   Discharge from sedimentation pond to the Huallaga River.
6MM   Surface water effluent   Discharge from the TSF to the Lloclla River.
6CH-F4   Surface water effluent   La Candelaria Hydroelectric Plant - Station 4.
16MM   Surface water effluent   Inflow to the Sanitary Wastewater Treatment Plant from the mine camp.
7MM   Receiving water body   Lloclla River upstream of the TSF.
8MM   Receiving water body   Lloclla River downstream of the TSF.
9MM   Receiving water body   Huallaga River upstream of the La Quinua tunnel outlet.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Station ID   Type of Water   Location
10MM   Receiving water body   Huallaga River downstream of the La Quinua tunnel outlet.
11MM1   Diverted water   TSF diversion channel before the discharge to the Lloclla River.
12MM   Surface water body   Tingovado Creek upstream of the diversion channel.
13MM   Groundwater   Spring.
14MM   Groundwater   Spring.
15MM*   Groundwater   Piezometer.

 

Note:

 

1. As of December 2019, this station had not been implemented (Nexa, 2020).

 

17.3 Project Permitting

 

El Porvenir complies with applicable Peruvian permitting requirements. The permits are RDs issued by the Peruvian authorities upon approval of mining environmental management instruments filed by the mining companies such as EIAs, ITSs, and Mine Closure Plans. The approved permits address the authority’s requirements for operation of the El Porvenir underground mine, TSF, concentrator plant, water usage, and effluents discharge.

 

Nexa maintains an up to date record of the legal permits obtained to date, documenting the approving authority, validity period and expiry dates, status (current, canceled or superseded), and indicating if renewal is required or not. The list of approved legal permits for El Porvenir provided to SLR by Nexa addresses the following aspects:

 

EIA certifications

 

Water use licences

 

Effluent discharge

 

Mine closure planning

 

Beneficiation concessions

 

Tailings management

 

Power generation

 

Licences for use of explosives

 

Absence of archaeological remains

 

The El Porvenir RDs on environmental certifications, effluent discharge, water use, mine closure and tailings management are listed in Table 17-3. According to the record of the legal permits provided by Nexa in November 2020, the approved environmental certifications (i.e. EIA and ITS) do not have expiry dates and therefore renewal dates are not applicable. The third amendment to the Mine Closure Plan is currently under review process by the Peruvian Authorities in order to renew the mine closure obligations that expired in September 2019.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Table 17-3: Environmental, Mine Closure, and Tailings Disposal Licences

Nexa Resources S.A. – El Porvenir Mine

 

Authority   Obligation/Licence   Date of Issue
(DD/MM/YYYY)
  Expiration Date
(DD/MM/YYYY)
  Status
Environmental Certifications
MINEM-DGM   PAMA (Programa de Adecuación y Manejo Ambiental) Approval
RD 023-1997-EM/DGM
  17/1/1997   None   Active
MINEM-DGE   PAMA Approval - Electric System (CH Candelaria + CT Milpo)
RD 028-1997-EM/DGE
  23/1/1997   None   Active
MINEM-DGAAM   EIA for Production Expansion of the Plant to 3,100 tpd
RD 379-2001-EM/DGAA
  26/11/2001   None   Active
MINEM-DGM   PAMA Approval of Execution
RD 288-2002-MEM/DGM
  7/11/2002   None   Active
MINEM-DGAAM   Modification of the EIA for Production Expansion of the Concentrator Plant to 5,500 tpd
RD 271-2011-MEM/AAM
  2/9/2011   None   Active
MINEM-DGAAM   EIA for Capacity Expansion of the Concentrator Plant to 7,500 tpd and Expansion of Cyclone Tailings
RD 203-2012-MEM/AAM
  25/6/2012   None   Active
MINEM-DGAAM   1st ITS El Porvenir – Transmission Line 220 kV Substation Paragsha II – Substation El Porvenir and Transmission Line 50 kV
RD 159-2014-MEM/DGAAM
  2/4/2014   None   Active
MINEM-DGAAM   2nd ITS El Porvenir – Integration Tailings Storage/Tailings Line Atacocha-El Porvenir (El Porvenir Zone) RD 526-2014-MEM/DGAAM   20/10/2014   None   Active
MINEM-DGAAM   IGA Ownership Change
Record 647-2015-MEM/DGAAM
  2/3/2015   None   Active
MINEM-DGAAM   3rd ITS El Porvenir – Approval “Variant to Ends of Transmission Line 220 kV-S.E. Paragsha II-SE El Porvenir and SE Milpo (El Porvenir), and tension reduction of Transmission Line from 220 kV to 138 kV"
RD 271-2015-MEM-DGAAM
  9/7/2015   None   Active
SENACE   4th ITS El Porvenir – Capacity Expansion of the Concentrator Plant to 9,0 tpd
RD 319-2017-SENACE-DCA dated October 24, 2017
  24/10/2017   None   Active

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Authority   Obligation/Licence   Date of Issue
(DD/MM/YYYY)
  Expiration Date
(DD/MM/YYYY)
  Status
SENACE   5th ITS El Porvenir – Auxiliary Components
RD 058-2018-SENACE-PE/DEAR
  13/12/2018   None   Active
SENACE   6th ITS El Porvenir – Introduction of Technical Improvements to the Concentrator Plant  
RD N° 51-2020-SENACE-PE/DEAR
  10/3/2020   None   Active
Effluent Discharge and Reuse Authorizations
ANA-DGCRH   Authorization for Discharge of Treated Industrial Residual Water from the Concentrator Plant
RD 014-2010-ANA-DGCRH
  10/8/2010   10/8/2012   Inactive Modified
ANA-DGCRH   Authorization for Domestic Residual Water Reuse for Irrigation
RD 005-2013-ANA-DGCRH
  7/1/2013   7/1/2015   Inactive Renewed
ANA   Renewal of Authorization for Discharge from LQ and Porvenir Underground Mine Portals
RD 172-2015-ANA-DGCRH
  15/6/2015   15/6/2019   Expired Not Renewed
AAA-HUALLAGA   Authorization for Water Reuse
RD 165-2015-ANA/AAA-HUALLAGA
  7/7/2015   7/5/2019   Expired Not Renewed
ANA   Renewal of Authorization for Discharge from LQ and Porvenir Underground Mine Portals
RD 192-2019-ANA-DCERH
  16/6/2019   16/6/2022   Active
ANA   Renewal of Authorization for Domestic Residual Water Reuse for Mining Purposes (Irrigation)
RD 600-2019-ANA/AAA-HUALLAGA
  6/7/2019   7/6/2025   Active
Water Use Licences
ANA   Mine Water Licence
RS 0392-1974-AG
  08/4/1974   None   Inactive
ANA   Mine and Camp Water Licence
RS 0057-76-AG/DGA
  4/3/1976   None   Inactive
ANA   Mine and Population Water Licence
RS 307-76-AG/DGA
  14/12/1976   None   Inactive
ANA   Power Generation Water Licence
RD 0020-92-AG-DGAS
  30/6/1992   None   Active
ANA   Power Generation Water Licence
RD 0029-92-AG-DGAS
  17/7/1992   None   Active
ANA   Population Industrial Water Licence
RA 0014-92-SRP-DGA/RN Y DR SAS
  13/12/1992   None   Inactive
ANA   Power Generation Water Licence
RA 001-93-DGA-SRPRN
  15/2/1993   None   Active

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Authority   Obligation/Licence   Date of Issue
(DD/MM/YYYY)
  Expiration Date
(DD/MM/YYYY)
  Status
ANA   Population Camp Water Licence
RA 011-98-AG-DSRAP/INRENA-ATDRP
  9/7/1998   None   Inactive
MINAGRI-ANA   Power Water Use Licence (Modification Ar1)
RD 127-2006-AG-DRA-P-A-TPDR
  22/12/2006   None   Inactive Modified
MINAGRI-ANA   Water for Population Use Licence (Modification Ar1)
RD 125-2006-AG-DRA-P/ATPDR
  22/12/2006   None   Inactive Modified
MINAGRI-ANA   Water for Mining Use Licence (Modification Ar1)
RD 126-2006-AG-DRA-P/ATPDR
  22/12/2006   None   Inactive Modified
ANA   Approval of Ownership Change to MAP - Water for Population Use Licence
RD 264-2015-ANA-AAA-X-MANTARO
  6/4/2015   None   Inactive
ANA/AAA-HUALLAGA   Approval of Ownership Change to MAP – Power Use
RD 086-2016-ANA/AAA-HUALLAGA
  11/2/2016   None   Not Applicable
ANA   Approval of Ownership Change to MAP - Water for Mining Use Licence
RD N° 399-2016-ANA/AAA-HUALLAGA
  13/6/2016   None   Inactive
ANA   Approval of Ownership Change to Nexa El Porvenir– Surface Water for Mining Use  
RA 322-2019-ANA-AAA-HUALLAGA-ALA ALTO HUALLAGA
  3/10/2019   None   Active
Mine Closure Plans
MINEM-DGAAM   El Porvenir Mine Closure Plan Approval
RD 166-2009-MEM/AAM
  17/6/2009   9/15/2019   Active Renewable
MINEM-DGAAM   El Porvenir Mine Closure Plan First Amendment
RD 286-2011-MEM/AAM
  15/9/2011   9/15/2019   Active Renewable
MINEM-DGAAM   El Porvenir Mine Closure Plan Update
RD 034-2013-MEM/AAM
  30/1/2013   9/15/2019   Active Renewable
MINEM-DGAAM   El Porvenir Mine Closure Plan Second Amendment
RD 277-2016-MEM/DGAAM
  15/9/2016   9/15/2019   Active Under Renewal
Tailings Management
MINEM-DGM   Beneficiation Concession for the Tailings Storage Facility
RD 280-97-EM/DGM
  12/8/1997   None   Active
MINEM-DGM   Beneficiation Concession for the Tailings Storage Facility
RD 281-97-EM/DGM
  12/9/1997   None   Active

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Authority   Obligation/Licence   Date of Issue
(DD/MM/YYYY)
  Expiration Date
(DD/MM/YYYY)
  Status
MINEM-DGM   Construction Authorization for Expansion of Tailings Storage Facility to Dam Elevation 4,043
RD 178-2010-MEM
  7/4/2010   None   Active
MINEM-DGM   Authorization for Operation of Tailings Storage Facility to Dam Elevation 4,043
RD 356-2010-MEM-DGM/V
  18/9/2010   None   Active
MINEM-DGM   Modification of Schedule for Expansion of the Tailings Storage Facility
RD 252-2014-MEM-DGM/V
  9/7/2014   None   Active
MINEM-DGM   Construction Authorization for New Components of Tailings Line from Profile Alignment Station 1+524m to El Porvenir Tailings Storage Facility
RD 0584-2014-MEM-DGM/V
  29/12/2014   None   Active
MINEM-DGM   Authorization for Operation of El Porvenir Tailings Storage Facility to Dam Elevation 4,047 and Expansion of the Beneficiation Concession “Aquiles 1 Accumulation” to 183.28 ha
RD 612-2015-MEM/DGM
  12/6/2015   None   Active
MINEM-DGM   Authorization for Operation of Tailings Pipeline El Porvenir
RD 194-2015-MEM-DGM-DTM/PB
  19/6/2015   None   Active
MINEM-DGM   Authorization for Operation of New Components of Tailings Line from Profile Alignment Station 1+524m to El Porvenir Tailings Storage Facility
RD 0251-2015-MEM-DGM/V
  19/6/2015   None   Active
MINEM-DGM   Authorization for Operation of Tailings Storage Facility Expansion to Dam Elevation 4,048.5
RD 0499-2016-MEM-DGM/V
  18/8/2016   None   Active
MINEM-DGM   Construction of Tailings Storage Facility Expansion to Dam Elevation 4,100 and Secondary Embankment at the Process Plant Side   
RD 006-2017-MEM-DGM/V
  9/1/2017   None   Active
MINEM-DGM   Authorization for Operation of Tailings Storage Facility Expansion to Dam Elevation 4,056 and Extension of Diversion Channel
RD 828-2017-MEM-DGM/V
  25/9/2017   None   Active
MINEM-DGM   Authorization for Operation of Tailings Storage Facility to Dam Elevation 4,060
RD 0498-2019-MEM-DGM/V
  7/10/2019   None   Active

 

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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17.4 Social or Community Requirements

 

17.4.1 General Context

 

Nexa’s Cerro Pasco mine complex includes both El Porvenir and the nearby Atacocha. The communities located within the area of direct influence are:

 

Comunidad de San Francisco de Asís de Yarusyacán

 

Anexo de Machcan

 

Anexo San Ramón de Yanapampa

 

Comunidad de Titaclayán

 

Centro Poblado San Isidro de Yanapampa

 

Comunidad de Cajamarquilla

 

Comunidad San Antonio de Malauchaca

 

This subsection presents the results of the social review based on a review of Nexa’s policies, programs, social risk management systems, and/or social performance against relevant International Finance Corporation (IFC) Performance Standards (PS). The IFC PSs have been used as a framework but this social review does not represent a detailed audit of Nexa’s compliance with IFC PSs or specific guidelines. Nexa’s social performance is benchmarked against the following IFC 2012 PSs:

 

PS1: Social and Environmental Assessment and Management Systems requires that companies identify, assess, and mitigate the social and environmental impacts and risks they generate throughout the lifecycle of their projects and operations. From a social perspective, the requirement includes: a comprehensive social assessment; identification of critical social impacts and risks; community consultation and engagement; information disclosure; mitigation plans to address impacts and risks; and development of an organizational structure with qualified staff and budgets to manage the overall social management system.

 

PS2: Labour and Working Conditions incorporates the ILO conventions that seek to protect basic worker rights and promote effective worker/management relations.

 

PS4: Community Health and Safety declares the project’s duty to avoid or minimize risks and impacts to community health and safety and addresses priorities and measures to avoid and mitigate project related impacts and risks that might generate community exposure to risks of accidents and diseases.

 

PS5: Land Acquisition and Involuntary Resettlement considers the need for land acquisition or involuntary resettlement of any individual, family or group; including the potential for economic displacement.

 

PS7: Indigenous Peoples considers the presence of Indigenous groups, communities, or lands in the area that may be directly or indirectly affected by projects or operations.

 

 

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PS8: Cultural Heritage. This standard is based on the Convention on the Protection of the World Cultural and Natural Heritage. The objectives are to preserve and protect irreplaceable cultural heritage during a project's operations, whether or not it is legally protected or previously disturbed and promote the equitable sharing of benefits from the use of cultural heritage in business activities.

 

SLR notes that PS3 Resource Efficiency and Pollution Prevention and PS6 Biodiversity Conservation correspond to environmental performance standards, which have been discussed at the beginning of Section 17 of this Technical Report Summary.

 

17.4.2 Social and Environmental Assessment and Management Systems

 

At a corporate level, Nexa has adopted the guidelines of the International Integrated Reporting Council (IIRC) and the standards for the Global Reporting Index (GRI). The IIRC guidelines promote a cohesive and integrated approach to reporting on organizational activities. The GRI standards provide best practices for public reporting on economic, environmental, and social impacts in order to aid Nexa and its shareholders and stakeholders understand their corporate contribution to sustainable development. These standards were reported on in the most recent Nexa Annual Report (Nexa, 2020e). With respect to social issues, the 2019 Annual Report provided details of corporate activities aligning with the following GRI Standards:

 

Employment

 

Occupational health and safety (OHS)

 

Non-discrimination

 

Training and education

 

Diversity and equal opportunities

 

Freedom of association and collective bargaining

 

Child labour

 

Forced or compulsory labour

 

Human rights assessment

 

Local communities

 

Social assessment of suppliers

 

Socio-economic compliance

 

Nexa’s 2019 Annual Report also includes reporting on corporate progress towards several sustainable development goals. With respect to social environment issues, these include:

 

Gender equality

 

Decent work and economic growth

 

Good health and well-being

 

Peace, justice, and strong institutions

 

Quality education

 

Reduced inequalities

 

Sustainable cities and communities

 

Responsible consumption and production

 

 

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Life below water

 

Nexa has a corporate compliance policy (PC-RCC-CCI-005-EN) meant to guide Nexa representatives and third parties. The compliance policy includes the following policies and procedures:

 

Code of Conduct

 

Anti-Corruption Policy

 

Money Laundering and Financing Terrorism Prevention Policy

 

Antitrust/Competition Policy

 

Insider Trading Policy

 

Disclosure Policy

 

Compliance Program Manual

 

Money Laundering and Financing Terrorism Prevention Manual

 

Gifts and Hospitality Procedure

 

Relationships with Government Representatives Procedure

 

Travel and Entertainment Procedure

 

Integrity Due Diligence Procedure

 

Conflict of Interests Procedure

 

Nexa has developed policies, protocols and operational procedures and practices that aim to address various aspects of the company’s social responsibility with regard to its mining operations. These policies, protocols and procedures have been designed to meet host country requirements and comply with IFC standard PS1 (“Environmental and Social Assessment and Management System (ESMS)”) requirements. These policies and procedures are updated periodically in response to changing local conditions throughout the mine life.

 

As required by IFC PS1, Nexa’s management system is based on an overarching Corporate policy defining the environmental and social objectives and principles that will guide the project to achieve sound environmental and social performance. Nexa’s policy aims to achieve the following:

 

Prevent, mitigate, minimize and control environmental impacts, occupational health and safety risks; training, motivating and listening to the opinion of its workers, to foster in them a culture regarding the environment, safety and health of the worker, as well as to its visitors and interested parties.

 

Ensure that all workers receive fair compensation according to the work they develop, as well as dignified working conditions, a conducive work environment and oriented to their working skills and personal development.

 

Develop activities in favor of the welfare of the populations that live near Nexa’s operations, respecting their culture and traditions.

 

Promote the continuous improvement of the effectiveness of the Management System, through compliance with environmental standards, quality, occupational safety and health, contained in legal requirements and other accepted by the organization.

 

Provide a product that satisfies the quality required by its customers, in a timely manner, optimizing production costs, innovating and being internationally competitive.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Also consistent with IFC PS1, Nexa’s Community Relationships Policy (SGI-GRS-P-15) aims to achieve the following:

 

Respect for communities’ culture, resources, and traditions.

 

Treating local communities as strategic allies, seeking to develop activities that are of mutual benefit.

 

Promoting local employment and job opportunities with preferential local suppliers.

 

Developing local capacities to achieve competitiveness.

 

Promoting the social role of the company as an active actor that contributes to the local development under the leadership of the state authority, be it local, regional or national.

 

Orienting all social development initiatives in a manner that promotes self-management and sustainability, promoting the contribution of the beneficiaries themselves and co- financing to achieve shared development.

 

Establishing the understanding among staff that social responsibility traverses the whole company.

 

Encouraging communication about the company’s activities in the locality of its operations.

 

Generating social and environmental assets from the mining activity.

 

A social baseline description, assessment of socio-economic impacts, and identification of mitigation actions have been carried out to mitigate negative impacts and maximize positive benefits of the El Porvenir Mine. These components are generally consistent with social impact assessment practices. A Community Relations Plan has been developed (included in the modification of the EIA from 2011) outlining objectives, strategies and specific indicators for the following programs: information and communication; support to social projects and productive investment projects; health services; education; technical training; training for social and environmental participatory monitoring; promotion of environmental awareness; compensation for land use; and improvement of houses in surrounding communities.

 

Nexa has a permanent information office dedicated to receiving, managing, and addressing complaints, claims, questions and information requests from the communities. To be proactive, Nexa has also developed a communications program that involves the following activities:

 

Distribution of informative material (Quarterly).

 

Social concern monitoring (Quarterly).

 

A complaint management process aimed at preventing and managing possible social conflicts in the area.

 

Meetings with local authorities (Quarterly).

 

Guided tours (Quarterly).

 

In 2019 a conflict was registered with Nexa and the community of San Juan de Yanacachi in the Pasco region of Peru, related to land use.

 

In the SLR QP’s opinion the grievance mechanism in place and the Community Relations Plan, in combination with Nexa’s Social Management Policy and Management Procedures on negotiation for land access, monitoring of social commitments, management of social crisis, promotion of local hiring, and communication with stakeholders, are adequate to address potential issues related to local communities.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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17.4.3 Labour and Working Conditions

 

Corporately, Nexa has affirmed its commitment to safe and positive labour and working conditions. The relevant Sustainable Development Targets identified by Nexa include, but are not limited to:

 

Achieving full and productive employment and decent work for all women and men, including young people and persons with disabilities, and equal pay for work of equal value by 2030.

 

Protecting labour rights and promote safe and secure working environments for all workers, including migrant workers, in particular migrant women, and persons in precarious employment.

 

Nexa has adopted OHS policies to ensure the protection and promotion of the safety, human health, and welfare of employees. Corporately, Nexa reports on its health and safety performance and highlights safety as its greatest asset. Several corporate initiatives are aimed at promoting safety, ensuring workers and contractors are trained, and that processes are in place to address any incidents that arise. Nexa has a management standard that outlines the process to communicate classify, analyze, and record potential accidents (near misses) and accidents in order to improve health and safety measures. Nexa also reports on the health and safety performance at all of their sites.

 

As approximately 75% of Nexa’s Peruvian operations are comprised of outsourced employees, special programs have been developed to ensure health and safety objectives are being met.

 

In 2017, Nexa created the Peru Safety Plan, which is a program having the objective of eliminating all fatalities, reducing the number and severity of accidents and enhancing the safety culture in the units across Peru. Over two and a half years, 244 initiatives were developed in 30 projects. At the end of 2019, Nexa had completed mapping and a critical analysis of its of activities. The safety of operations in Peru was recognized by the Peruvian Mining Safety Institute (Instituto de Seguridad Minera (Isem)), which recognized the Atacocha unit for the lowest accident rate and absence of fatal accidents in the underground mining category in the last 12 months of operations.

 

In 2019, Nexa also launched the 100% safe campaign to raise the awareness of employees of partner companies about safe behavior, encouraging reflection on the actions of each person in routine tasks. Despite these efforts, one fatality in its Peruvian operations was reported in Nexa’s 2019 Annual Report.

 

Corporately, Nexa has stated its commitment to internationally recognized human rights and prohibits any violation of human rights in its operations and suppliers. Suppliers are asked to provide information regarding both social responsibility and human rights preservation. Nexa reported that in 2019, there were no complaints of non-compliance with any requirements related to human rights impacts, across all of its operations. Furthermore, Nexa is also seeking to review all outside suppliers for their conformity with human rights ethics. As of 2019, approximately half of its suppliers had been reviewed, with no known records of any human rights violations.

 

There are procedures in place for employees and contractors to report grievances and ethical violations, including directly to management, via telephone and online. At the time of this writing, there were no specific reports on the number of grievances or ethical violations relevant to the Cerro Pasco mine complex.

 

Commitments previously established between Milpo and the San Juan de Milpo Community include the prioritization of permanent employment opportunities regardless of gender for the duration of the ongoing mine operations; in the event that a sub-contractor ceases its involvement with the mine operation, Nexa will re-assign personnel from the community to other activities.

 

 

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As part of the Marco Agreement previously established between Nexa and the San Francisco de Asis de Yarusyacan Community, Nexa is committed to employ 60% of workers from specialized service companies from the community, dependent on employment opportunities required by the mine operations (both El Porvenir and Atacocha) for qualified and non-qualified workforce.

 

Employees have access to a number of benefits including paid vacations and holidays, financial bonuses, health, education, overtime, living allowance, and other employment bonuses.

 

17.4.4 Community Health and Safety

 

Corporately, Nexa has made several commitments to improve community health and safety, as well as the overall well-being of community members.

 

Nexa supports social health and community well being through a number of community based initiatives in Nexa’s areas of influence. The 2018 EIA set out the components of Nexa’s social responsibility program, including:

 

Communications with local communities and stakeholders.

 

Mitigation of social impacts and provision of job opportunities.

 

Managing social circumstances that could result in social conflict.

 

Promoting local employment, particularly among youth.

 

Acquisition of local products, goods and services.

 

Enhancing livestock operations.

 

Implementing medical campaigns to improve health conditions.

 

Provision of school supplies to children.

 

Water management.

 

Support of local festivities.

 

Support for local infrastructure / community projects.

 

Strengthening of local capabilities.

 

For instance, in 2019, to strengthen local development processes Nexa supported the development of spaces for dialogue and interaction with public, private, and community institutions. From this, local governments, service providers and users began to manage drinking water services more sustainably, improving their performance in the management of public services and their role in local development.

 

In 2019, Nexa implemented a safe school program to improve health conditions of students at five schools located in El Porvenir and Atacocha.

 

In 2019, Nexa verified its emergency response conditions at all operating units in Peru and an Emergency Response Plan (PAE for its acronym in Spanish) was delivered with management training and simulated exercises. A Global Emergency Response Plan is in development, to align the actions of the individual unit plans with the corporate Crisis and Business Continuity Management Plan.

 

In 2020, Nexa reported that the authorities of the countries which they operate have adopted policies referring to the COVID-19 pandemic declared by the World Health Organization (WHO), such as the state of emergency declared by the Peruvian government. Nexa has also been in discussions with local stakeholders to develop protocols and programs to monitor and manage the risk of COVID-19 including on-site and with the movement of workers on and off-site.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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17.4.5 Land Acquisition and Involuntary Resettlement

 

At the time of writing, there does not appear to be any land acquisition or involuntary resettlement associated with the Cerro Pasco complex operations. Therefore, the SLR QP is of the opinion that PS5 is not applicable.

 

17.4.6 Indigenous Peoples

 

There are no Indigenous Peoples in the vicinity of the Cerro Pasco complex. Therefore, the SLR QP is of th opinion that PS7 does not appear to be applicable.

 

17.4.7 Cultural Heritage

 

Projects of archaeological evaluation have been undertaken in the El Porvenir area. A number of certificates of absence of archaeological remains (CIRA for its acronym in Spanish) have been issued to Milpo by the National Ministry of Culture approving the supporting documentation submitted in writing by the mining company to the ministry for review and approval. At the time of writing, no information was available on Chance Find Procedures, which might be applicable as the proposed expansion undergoes construction and expanded operations commence.

 

17.4.8 Conclusions and Recommendations

 

SLRs review of social aspects indicates that, at present, Nexa’s Cerro Pasco complex, is a positive contribution to sustainability and community well being. Nexa has established and continues to implement its various corporate policies, procedures, and practices in a manner consistent with relevant IFC PSs. Nexa has, and continues to make, a positive contribution to the communities most affected by the site operations and has done a thorough job in documenting potential effects on stakeholders and protecting the rights, health and safety of its employees.

 

At this time, there are no specific recommendations to improve Nexa’s social performance at the Cerro Pasco complex. Outreach, dialogue, and clear documentation should continue, particularly through the COVID-19 pandemic.

 

17.5 Mine Closure Requirements

 

17.5.1 Mine Closure Plan and Regulatory Requirements

 

The Mine Closure Plan is periodically updated over the LOM. A conceptual Mine Closure Plan was prepared in 2006 for the Mine components within the context of the Peruvian legislation (KCB, 2006) and has subsequently been amended or updated four times. The Mine Closure Plan addresses temporary, progressive, and final closure actions, and post-closure inspection and monitoring. Under Article 20 of the Peruvian mine closure regulations, the first update of the Mine Closure Plan must be submitted to the Peruvian Ministry of Energy and Mines (the Ministry) three years after approval of the initial Mine Closure Plan, and every five years thereafter. Two years before final closure, a detailed version of the Mine Closure Plan will have to be prepared and submitted to the Ministry for review and approval. The following is a summary of the El Porvenir Mine Closure Plan updates and modifications to date:

 

Initial Closure Plan approved in 2007 by R.D. No. 318-2007-MEM/AAM and prepared according to the modification of Supreme Decree D.S. No. 033-2005-EM (Mine Closure Law).

 

Feasibility level Mine Closure Plan approved in 2009 by R.D. No. 166-2009-MEM-AAM.

 

 

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First amendment to the Mine Closure Plan approved in 2011 by R.D. No. 286-2011-MEM-AAM.

 

Update of the Mine Closure Plan approved in 2013 by R.D. No. 034-2013-MEM-AAM.

 

Second amendment to the Mine Closure Plan approved in 2016 by R.D. No. 277-2016-MEM-AAM.

 

Third amendment to the Mine Closure Plan prepared in January 2020 and submitted to the Peruvian Ministry of Energy and Mines for approval.

 

The Conceptual Mine Closure Plan approved in 2007 (KCB, 2006), the R.D. from 2009, the update to the Mine Closure Plan approved in 2013 (Schlumberger Water Services, 2012), and the third amendment to the Mine Closure Plan (KCB, 2020) were available for review.

 

The approved period for implementation of closure and post-closure in the latest Mine Closure Plan includes seven years of progressive closure (2021 to 2027), two years of final closure (2028 to 2029), and five years of post-closure (2030 to 2034). Post-closure monitoring, assumed to extend for five years after closure, will include monitoring of physical, geochemical, hydrological, and biological stability.

 

The specific objectives of the El Porvenir Mine Closure Plan are as follows:

 

Health and safety – Assure public health and safety during execution of closure and post-closure activities, recovering the original environmental quality of the surroundings and developing feasible rehabilitation works from a biological, technical and financial perspective. Protect the human health and the environment by maintaining physical and chemical stability of Mine components.

 

Physical stability – Geotechnical stability of earth structures implementing designs that minimize short term and long term risks of failure following the applicable Peruvian legislation and best international practices.

 

Geochemical stability – Feasibility design of encapsulating covers for hazardous materials and materials with potential to cause contamination of the environment. The covers should be designed to employ local materials with physical and geochemical characteristics resistant to degradation and erosion through time. The covers should be compatible with the landscape, favourable to the growth of local vegetation species.

 

Hydrological stability – Adequate management of surface runoff. Design flows with adequate return period according to the applicable Peruvian legislation should be evaluated. The need for closure water management structures should be identified.

 

Land use – Recovery of original levels for ground surface to the extent feasible in order to make it compatible with predevelopment land uses in the project area.

 

Waterbodies use – Maintain equilibrium in the micro-basins located in the mine area, preserving water quantity and quality, and implementing adequate water management.

 

Social objectives – Minimize socio-economic impacts creating conditions that promote sustainability for the social stakeholders through execution of social programs.

 

The Mine Closure Plan promotes to the extent feasible a passive condition that minimizes the efforts required for care and maintenance of the closed Mine components during post-closure.

 

The closure criteria for each component of El Porvenir are defined according to the following aspects:

 

Dismantling

 

Demolition, salvage and disposal

 

Physical stabilization

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Geochemical stabilization

 

Hydrological stability (water management)

 

Re-establishing the landscape contour

 

Re-vegetation

 

Rehabilitation of aquatic habitats

 

Social programs

 

Post-closure maintenance and monitoring

 

The Mine Closure Plan concentrates on the decommissioning and closure of primary facilities and elements of infrastructure at El Porvenir, which include:

 

Underground mine and associated portal, ventilation shafts, support facilities, and underground infrastructure.

 

Processing facilities (concentrator plant and associated infrastructure).

 

WRDs.

 

TSF.

 

Water management facilities and infrastructure.

 

Borrow areas and quarries.

 

Mine camps (San Juan de Milpo and Carmen Chico) and administrative buildings.

 

Access roads.

 

Ancillary buildings.

 

Ancillary infrastructure including among others:

 

Electrical and ventilation systems.

 

Transportation systems.

 

Communication systems.

 

Domestic waste landfill.

 

Waste management facilities.

 

Organic waste management facilities.

 

La Candelaria Hydroelectric Plant.

 

Power transmission lines and electrical sub-stations.

 

Topsoil deposits.

 

A summary of the main proposed closure activities is presented in Table 17-4. Of note the that water supply to the San Juan de Milpo community from the Carmen Chico spring will be retained during post-closure.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Table 17-4: Summary of Main Closure Activities

Nexa Resources S.A. – El Porvenir Mine

 

Mine Component   Closure Activities
Mine Underground mine   Redirection of underground mine water discharge towards the TSF.
Flooding of underground works (recovery of phreatic level).
Plugging or filling of mine openings.
Disconnection, dismantling and removal of equipment and water management infrastructure.
Soil sampling to evaluate contamination.
Excavation/removal of contaminated material (including concrete) for appropriate disposal.
  La Quinua WRD   Slope contouring for physical stability.
Cover installation and revegetation.
Construction of an erosion prevention structure on the slope adjacent of the Huallaga River.
Waste disposal facilities TSF   Dam reconfiguration, if required for physical stability.
Leveling and recontouring of the disposed tailings surface.
Cover installation to prevent oxidation of the deposited tailings.
Re-vegetation.
Replacement of the overflow tunnel with a closure overflow spillway that discharges surface runoff to the Milpo Creek.
Improvements to the drainage system near the confluence of the Milpo Creek and the Lloclla River to prevent flooding the area of the San Miguel community.
Other infrastructure Concentrator plant
Shops
Water management infrastructure
Power transmission lines
Hazardous waste storage areas
Access roads
La Candelaria Hydroelectric Plant
  Dismantling, demolition, salvaging and disposal of structures.
(Donation of facilities to the local community will be considered on grounds of safety).
Disposal of concrete in the underground mine.
Removal of equipment for recycling, salvaging or disposal.
Removal of contaminated soils.
Transportation to authorized disposal areas.
Cleaning and purification of tanks and deposits.
Removal of Socorro pond.
Recontouring of terrain and re-vegetation.
Sale of the hydroelectric power plant to a third party that could continue the power supply to local communities.
Staff facilities Mine camp
Administrative buildings
Potable water and septic systems
  Mobilization of equipment, machinery, and personnel.
De-energization.
Dismantling and removal of structures and equipment to authorized disposal areas.
Dismantling and demolition of concrete structures for disposal in the underground mine.
Recontouring of terrain and re-vegetation.

 

 

It is noted that the design criteria for the El Porvenir TSF closure planning are to Peruvian Standards, which are less stringent than Canadian dam safety guidelines. For example, the El Porvenir tailings dam has been designed to meet stability requirements for a 2,500 year return earthquake with estimated peak ground acceleration of 0.4 times the acceleration due to gravity, which is significant. Post-seismic stability analyses for El Porvenir dam were carried out by Ausenco (2016) to demonstrate dam stability but no information was provided related to the risk of failure of the emergency spillway inlet control structure and the potential for liquefied tailings release through the spillway tunnel. The ultimate tailings level is some 50 m above the spillway tunnel invert.

 

 

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The El Porvenir TSF emergency spillway has been designed to pass the Probable Maximum Flood resulting from 146 mm of precipitation in 6 hours, which is appropriate given the size of the dam. It is not clear that the post-closure flood routing assumed the perimeter watershed diversion channels would still be in service in the long term. The risk of diversion channel blockage and potentially higher inflows to the TSF should be evaluated with additional freeboard added to the dam crest, if required, to ensure the dam is not overtopped.

 

A comprehensive dam safety review is recommended in order to finalize the detailed closure plan prior to moving into the closure stage.

 

Physical, chemical, hydrological, and biological stability conditions following closure will be verified through implementation of the post-closure maintenance and monitoring program. Monitoring will also support the evaluation and verification of compliance with closure activities, and the identification of deviations leading to the adoption of corrective measures. The monitoring activities will be carried out considering the Peruvian Environmental Quality Standards and Maximum Permissible Limits, as well as criteria set in the Mine Closure Plan for physical, chemical, hydrological, and biological stability.

 

No specific details of the post-closure monitoring programs for physical stability, water quality, biology and social were found in the Mine Closure Plan reports provided to SLR. Hence, SLR recommends to either confirm if these programs have been sufficiently advanced at a concept level or if details should be incorporated to the next update of the Mine Closure Plan for El Porvenir. As a minimum, it is recommended that post-closure monitoring programs include the following:

 

Specific activities and frequency to monitor physical and hydrological stability (mainly focused on inspections).

 

Locations and frequency for water quality sampling (surface water and groundwater).

 

Biology campaigns and frequency.

 

Indicators to track progress with social initiatives and programs implemented during the operations phase towards achieving social objectives at closure and post-closure.

 

Proposed documentation and reporting.

 

17.5.2 Closure Cost Estimate and Financial Assurance for Closure

 

A closure cost estimate was developed and included in the Mine Closure Plans. The total value estimated in 2020 for the remaining LOM presented in the third amendment to the Mine Closure Plan is as follows (excluding local taxes):

 

Progressive Closure (2021 to 2027) US$10,990,121

 

Final Closure (2028 to 2029) US$12,583,266

 

Post-Closure (2030 to 2034) US$ 1,622,646

 

Total US$25,196,033

 

 

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According to Supreme Decree D.S. N° 262-2012-MEM/DM, the financial assurance is calculated based on inflation and discount rates in order to estimate the net present value (NPV) for the mine closure cost. The total financial assurance (progressive closure, final closure, and post-closure) calculated in 2020 considering an inflation rate of 2.37% and a discount rate of 2.14%, is US$20,635,472 (including local taxes). A detailed breakdown of the cost estimate is provided in the third amendment to the El Porvenir Mine Closure Plan (KCB, 2020).

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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18.0 Capital and Operating Costs

 

For the purpose of this Technical Report Summary, SLR reviewed the capital and operating costs required for the mining and processing of Mineral Reserves at El Porvenir provided by Nexa. The capital and operating cost estimates were prepared based on recent operating performance and the current operating budget for 2020. SLR considers these cost estimates to be reasonable, as long as the production targets are realized. All costs in this section are expressed in Q4 2020 US dollars.

 

18.1 Capital Costs

 

Table 18-1 presents the LOM budget for capital expenditures at El Porvenir. The Mine is a current producer, therefore there are no pre-production capital costs. Capital expenditures are considered sustaining capital as they replace existing production assets, maintain current capacity, or are related to safety, health, and the environment. Underground mine development capital is based on a cost per development metre of US$1,396/m. The LOM sustaining capital costs for El Porvenir are estimated to be US$221 million.

 

Table 18-1: Life of Mine Capital Budget

Nexa Resources S.A. – El Porvenir Mine

 

Cost
(US$000)
  Total   2021   2022   2023   2024   2025   2026   2027   2028
Tailing Dam & Waste Deposit                                    
Raising   53,858   10,808   18,149   24,900   -   -   -   -   -
New Dam   13,246   2,700   1,000   -   5,000   4,546   -   -   -
Tailing Treatment   3,782   3,782   -   -   -   -   -   -   -
Heavy Mobile Equipment                                    
Replacement   23,284   1,838   50   3,567   4,781   5,593   3,641   3,815   -
Addition   3,335   850   1,600   -   -   -   -   -   -
Asset Integrity                                    
Asset Integrity – Plant   11,365   6,605   2,805   475   575   705   100   100   -
Asset Integrity – Mine   150   -   -   -   -   150   -   -   -
Other Sustaining                                    
Others   1,340   110   550   250   290   100   0   40   -
Civil Construction   200   200   -   -   -   -   -   -   -
Mining Facilities                                    
Communication system   2,450   550   700   600   300   300   -   -   -
Pumping   2,500   700   300   300   300   300   300   300   -
Electrical Substation   1,650   1,000   200   450   -   -   -   -   -

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Cost
(US$000)
  Total   2021   2022   2023   2024   2025   2026   2027   2028
Ventilation / Cooling   950   100   150   100   150   150   150   150   -
Operation Unit Projects                                    
Improvements   4,631   1,821   1,110   1,700   -   -   -   -   -
Audit & Inspection   2,380   390   890   1,100   -   -   -   -   -
Other Expenditures                                    
Expansion Projects   -   -   -   -   -   -   -   -   -
Information Technology   1,020   480   150   130   130   130   -   -   -
Automation Project   2,190   874   1,166   150   -   -   -   -   -
Mine Development Capital Cost                                    
Underground Mine Development   92,745   17,170   16,073   16,941   18,954   13,124   6,521   1,934   2,030
Total   221,075   49,977   44,894   50,663   30,479   25,982   10,712   6,338   2,030

 

The Mine Closure Plan was prepared to meet the Peruvian national requirements with the closure and reclamation cost assessed at US$25.2 million. The closure cost should be reviewed and updated regularly to address updates in the national requirements.

 

18.2 Operating Costs

 

The El Porvenir operating costs are based on a LOM period of eight years between 2021 and 2028. The operating cost inputs including labour, consumables, and supplies were based on data provided by Nexa and reflect the existing operating status of the Mine. Table 18-2 presents the LOM forecast for operating costs at El Porvenir and Table 18-3 lists Nexa personnel working at the Mine as of December 31, 2020.

 

Table 18-2: Operating Budget

Nexa Resources S.A. – El Porvenir Mine

 

All-In Cost
(US$000)
  Total   2021   2022   2023   2024   2025   2026   2027   2028
Mine Underground   454,350   63,077   64,320   64,742   61,913   55,796   51,610   51,569   41,323
High Zone C&F   127,409   22,074   19,242   20,828   15,955   8,275   13,293   13,374   14,369
High Zone SLS   4,947   301   1,818   2,354   473   -   -   -   -
Intermediate C&F   49,425   19,329   11,914   12,146   4,161   1,874   -   -   -
Intermediate SLS   90,866   8,801   11,734   11,978   21,170   17,064   3,651   3,673   12,795
Low Zone C&F   30,666   11,827   11,445   4,944   13   861   1,577   -   -
Low Zone SLS   8,855   636   366   797   3,358   3,698   -   -   -
Deepening C&F   98,132   -   5   5,621   15,239   19,778   21,641   23,630   12,218
Deepening SLS   44,050   109   7,795   6,074   1,546   4,246   11,448   10,892   1,941
Processing   176,174   23,274   23,452   23,446   22,910   21,808   20,998   20,972   19,314
G&A   101,109   15,774   16,219   16,206   14,861   12,103   10,076   10,011   5,858
Development Operating Cost   90,887   17,162   15,971   14,837   13,065   10,602   8,673   6,244   4,332
Total   822,519   119,288   119,961   119,231   112,750   100,309   91,356   88,797   70,827

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Table 18-3: Nexa Personnel at El Porvenir Mine – December 31, 2020

Nexa Resources S.A. – El Porvenir Mine

 

Department   Personnel
Business Intelligence   12
Human Resources   18
Geology - Mine   26
Management   4
Logistics   8
Maintenance   124
Mine   210
Open Pit Mine   1
Plant   63
Community Relations   5
Safety   13
Technical Services   28
Environment   4
Projects   9
Total   525

 

 

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19.0 Economic Analysis

 

The economic analysis contained in this Technical Report Summary is based on the Mineral Reserves, economic assumptions provided by Nexa for El Porvenir, and the capital and operating costs as presented in Section 18 of this Technical Report Summary.

 

19.1 Economic Criteria

 

19.1.1 Physicals

 

Mine life: 8 years (between 2021 and 2028):

 

Underground ore tonnes mined:            13.85 Mt

 

Cu grade: 0.23% Cu

 

Zn grade: 3.75% Zn

 

Pb grade: 0.88% Pb

 

Ag grade: 62.8 g/t Ag

 

Processed:

 

Total Ore Feed: 13.85 Mt

 

Cu grade: 0.23% Cu

 

Zn grade: 3.75% Zn

 

Pb grade: 0.88% Pb

 

Ag grade: 62.8 g/t Ag

 

Contained Metal:

 

▪  Cu: 31,500 t Cu

 

▪  Zn: 518,900 t Zn

 

▪  Pb: 122,400 t Pb

 

▪  Ag: 27.966 million ounces (Moz) Ag

 

Average LOM Recoveries:

 

Cu recovery 14.3%

 

Zn recovery 89.5%

 

Pb recovery 78.8%

 

Ag in Cu recovery 3.8%

 

Ag in Zn recovery 14.6%

 

Ag in Pb recovery 59.1%

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Recovered Metals:

 

▪  Cu: 4,500 t Cu

 

▪  Zn: 464,700 t Zn

 

▪  Pb: 96,800 t Pb

 

▪  Ag: 21.676 Moz Ag

 

Payable Metals:

 

▪  Cu: 4,300 t Cu

 

▪  Zn: 390,700 t Zn

 

▪  Pb: 91,200 t Pb

 

▪  Ag: 16.664 Moz Ag

 

19.1.2 Revenue

 

Revenue is estimated based on the following LOM weighted average metal prices:

 

Cu price: US$6,388/t Cu

 

Zn price: US$2,511/t Zn

 

Pb price: US$1,977/t Pb

 

Ag price: US$17.20/oz Ag

 

Net Revenue includes the benefit of additional US$128.7/t Zn selling price and zinc smelting at cost (rather than at commercial third-party terms), due to integration with Nexa’s Cajamarquilla refinery.

 

Logistics, Treatment (TC), and Refining (RC) charges:

 

LOM average Transportation/Logistics charges:

 

Cu concentrate: US$127.05/t concentrate for export

 

Zn concentrate: US$38.03/t concentrate to Cajamarquilla refinery

 

Pb concentrate: US$123.84/t concentrate for export

 

Treatment Charges:

 

TC+RC Cu concentrate: US$111.68/t concentrate

 

TC Zn concentrate for export: US$238.72/t concentrate

 

TC Pb concentrate: US$201.68/t concentrate

 

Refined Zn conversion costs at Cajamarquilla: US$509.73/t

 

Refining Charges:

 

Ag in Cu concentrate: US$0.50/oz

 

Ag in Pb concentrate: US$1.00/oz

 

NSR Revenue after logistics, treatment, and refining charges is US$1,306 million.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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19.1.3 Capital Costs

 

LOM sustaining capital costs of US$221.1 million.

 

Closure costs of US$25.2 million were included at the end of the Mineral Reserves based LOM in year 2029.

 

19.1.4 Operating Costs

 

LOM unit operating cost average of:

 

Mine Development: US$6.56/t mined

 

Underground Mining: US$32.81/t mined

 

Processing: US$12.72/t milled

 

G&A: US$7.30/t milled

 

Total unit operating costs of US$59.39/t milled.

 

LOM operating costs of US$822.5 million.

 

19.1.5 Taxation and Royalties

 

Corporate income tax rate in Peru is 29.50%.

 

Special Mining Tax (IEM/GEM) LOM average rate: 4.3%.

 

Mining royalties LOM average rate: 4.3%.

 

Employees participation: 8%.

 

SLR has relied on a Nexa taxation model for calculation of income taxes applicable to the cash flow.

 

19.2 Cash Flow

 

SLR developed a LOM after-tax cash flow model for El Porvenir to confirm the economics of the Nexa LOM plan. The model is based on Nexa’s TR EP 2020 v6 Final model. The model does not take into account the following components:

 

Financing costs

 

Insurance

 

Overhead cost for a corporate office

 

A cash flow summary is presented in Table 19-1. All costs are in Q4 2020 US dollars with no allowance for inflation.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

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Table 19-1: After-Tax Cash Flow Summary 

Nexa Resources S.A. – El Porvenir Mine

 

    INPUTS   UNITS   TOTAL     2021 Year 1     2022 Year 2     2023 Year 3     2024 Year 4     2025 Year 5     2026 Year 6     2027 Year 7     2028 Year 8     2029 Year 9  
Operating Days       360 days     2,880       360       360       360       360       360       360       360       360     -  
Tonnes milled per day       tonnes / day     4,809       6,002       6,171       6,166       5,655       4,605       3,834       3,809       2,229     -  
                                                                                       
Production       '000 tonnes     13,850       2,161       2,222       2,220       2,036       1,658       1,380       1,371       802     -  
Ag Grade       oz/t     2.02       2.33       1.98       2.14       1.99       1.68       1.82       1.90       2.25     -  
Cu Grade       %     0.23 %     0.17 %     0.21 %     0.24 %     0.25 %     0.24 %     0.27 %     0.28 %     0.17 %   0.00 %
Pb Grade       %     0.88 %     1.12 %     0.92 %     1.02 %     0.96 %     0.71 %     0.67 %     0.66 %     0.70 %   0.00 %
Zn Grade       %     3.75 %     3.28 %     3.69 %     3.57 %     3.82 %     4.11 %     4.25 %     4.01 %     3.39 %   0.00 %
Waste       '000 tonnes     -       -       -       -       -       -       -       -       -     -  
Total Moved       '000 tonnes     13,850       2,161       2,222       2,220       2,036       1,658       1,380       1,371       802     -  
                                                                                       
G                                                                                      
        '000 tonnes     13,850       2,161       2,222       2,220       2,036       1,658       1,380       1,371       802     -  
Ag Grade       oz/t     2.02       2.33       1.98       2.14       1.99       1.68       1.82       1.90       2.25     -  
Cu Grade       %     0.23 %     0.17 %     0.21 %     0.24 %     0.25 %     0.24 %     0.27 %     0.28 %     0.17 %   0.00 %
Pb Grade       %     0.88 %     1.12 %     0.92 %     1.02 %     0.96 %     0.71 %     0.67 %     0.66 %     0.70 %   0.00 %
Zn Grade       %     3.75 %     3.28 %     3.69 %     3.57 %     3.82 %     4.11 %     4.25 %     4.01 %     3.39 %   0.00 %
Contained Ag       oz     27,965,761       5,037,666       4,409,638       4,746,118       4,057,486       2,792,588       2,511,290       2,603,951       1,807,025     -  
Contained Cu       tonnes     31,463       3,717       4,563       5,355       4,997       3,937       3,680       3,869       1,345     -  
Contained Pb       tonnes     122,389       24,185       20,427       22,568       19,543       11,778       9,195       9,057       5,636     -  
Contained Zn       tonnes     518,941       70,920       81,954       79,208       77,797       68,200       58,663       55,016       27,184     -  
                                                                                       
de                                                                                      
Cu Concentrate   Recovery #1   %                                                                              
Ag             3.80 %     3.8 %     3.8 %     3.8 %     3.8 %     3.8 %     3.8 %     3.8 %     3.8 %   0.0 %
Cu             14.3 %     14.3 %     14.3 %     14.3 %     14.3 %     14.3 %     14.3 %     14.3 %     14.3 %   0.0 %
Pb             0 %     0 %     0 %     0 %     0 %     0 %     0 %     0 %     0 %   0 %
Zn             0 %     0 %     0 %     0 %     0 %     0 %     0 %     0 %     0 %   0 %
Pb Concentrate   Recovery #2   %                                                                              
Ag             59.1 %     59.1 %     59.1 %     59.1 %     59.1 %     59.1 %     59.1 %     59.1 %     59.1 %   0.0 %
Cu             0 %     0 %     0 %     0 %     0 %     0 %     0 %     0 %     0 %   0 %
Pb             78.8 %     80.5 %     79.6 %     80.2 %     79.9 %     77.1 %     76.4 %     76.3 %     77.0 %   0.0 %
Zn             0 %     0 %     0 %     0 %     0 %     0 %     0 %     0 %     0 %   0 %
Zn Concentrate   Recovery #3   %                                                                              
Ag             14.59 %     14.6 %     14.6 %     14.6 %     14.6 %     14.6 %     14.6 %     14.6 %     14.6 %   0.0 %
Cu             0 %     0 %     0 %     0 %     0 %     0 %     0 %     0 %     0 %   0 %
Pb             0 %     0 %     0 %     0 %     0 %     0 %     0 %     0 %     0 %   0 %
Zn             89.55 %     89.3 %     89.6 %     89.6 %     89.6 %     89.6 %     89.6 %     89.6 %     89.4 %   0.0 %
Net Recovery       %                                                                              
Ag             77.5 %     78 %     78 %     78 %     78 %     78 %     78 %     78 %     78 %   0 %
%Cu             14.3 %     14 %     14 %     14 %     14 %     14 %     14 %     14 %     14 %   0 %
Pb             78.8 %     81 %     80 %     80 %     80 %     77 %     76 %     76 %     77 %   0 %
Zn             89.5 %     89 %     90 %     90 %     90 %     90 %     90 %     90 %     89 %   0 %
Total Average Recovery             77.7 %     78 %     78 %     78 %     78 %     78 %     78 %     78 %     78 %      
                                                                                       
mount                                                                                      
Cu Concentrate   Recovery #1                                                                                  
Ag       oz     1,062,699       191,431       167,566       180,352       154,184       106,118       95,429       98,950       68,667     -  
Cu       tonnes     22,662       2,677       3,286       3,857       3,599       2,836       2,651       2,787       969     -  
Pb       tonnes     -       -       -       -       -       -       -       -       -     -  
Zn       tonnes     -       -       -       -       -       -       -       -       -     -  
Pb Concentrate   Recovery #2                                                                                  
Ag       oz     16,533,358       2,978,268       2,606,978       2,805,905       2,398,786       1,650,978       1,484,675       1,539,456       1,068,313     -  
Cu       tonnes     -       -       -       -       -       -       -       -       -     -  
Pb       tonnes     185,932       37,412       31,218       34,767       29,982       17,446       13,495       13,276       8,335     -  
Zn       tonnes     -       -       -       -       -       -       -       -       -     -  
Zn Concentrate   Recovery #3                                                                                  
Ag       oz     4,080,205       734,995       643,366       692,459       591,987       407,439       366,397       379,916       263,645     -  
Cu       tonnes     -       -       -       -       -       -       -       -       -     -  
Pb       tonnes     -       -       -       -       -       -       -       -       -     -  
Zn       tonnes     925,961       126,124       146,334       141,431       138,910       121,774       104,746       98,234       48,407     -  

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

19-4

 

 

    INPUTS     UNITS   TOTAL     2021 Year 1     2022 Year 2     2023 Year 3     2024 Year 4     2025 Year 5     2026 Year 6     2027 Year 7     2028 Year 8     2029 Year 9  
centrate                                                                                            
Cu Concentrate           dmt     22,662       2,677       3,286       3,857       3,599       2,836       2,651       2,787       969       -  
Ag grade in concentrate           oz/t     46.89       71.51       50.99       46.76       42.84       37.42       36.00       35.51       70.89       -  
Cu grade in concentrate     19.8 %   %     19.84 %     19.84 %     19.84 %     19.84 %     19.84 %     19.84 %     19.84 %     19.84 %     19.84 %     19.84 %
Pb grade in concentrate           %     0.00 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %        
Zn grade in concentrate           %     0.00 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %        
Concentrate Moisture     10 %                 10.0 %     10.0 %     10.0 %     10.0 %     10.0 %     10.0 %     10.0 %     10.0 %     10.0 %
Cu Concentrate           wmt     25,179       2,975       3,651       4,286       3,999       3,151       2,945       3,097       1,076       -  
                                                                                             
Pb Concentrate           dmt     185,932       37,412       31,218       34,767       29,982       17,446       13,495       13,276       8,335       -  
Ag grade in concentrate           oz/t     88.92       79.61       84       81       80       95       110       116       128       -  
Cu grade in concentrate           %     0.00 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %        
Pb grade in concentrate     52.06 %   %     52.06 %     52.06 %     52.06 %     52.06 %     52.06 %     52.06 %     52.06 %     52.06 %     52.06 %     52.1 %
Zn grade in concentrate           %     0.00 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %        
Concentrate Moisture     10 %                 10.0 %     10.0 %     10.0 %     10.0 %     10.0 %     10.0 %     10.0 %     10.0 %     10.0 %
Pb Concentrate           wmt     206,591       41,569       34,686       38,630       33,314       19,384       14,995       14,751       9,261       -  
                                                                                             
Zn Concentrate           dmt     925,961       126,124       146,334       141,431       138,910       121,774       104,746       98,234       48,407       -  
Ag grade in concentrate           oz/t     4.41       5.83       40.       4.90       4.26       3.35       3.50       3.87       5.45       -  
Cu grade in concentrate           %     0.00 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %        
Pb grade in concentrate           %     0.00 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %        
Zn grade in concentrate     50.19 %   %     50.19 %     50.19 %     50.19 %     50.19 %     50.19 %     50.19 %     50.19 %     50.19 %     50.19 %     50.19 %
Concentrate Moisture     10 %                 10.0 %     10.0 %     10.0 %     10.0 %     10.0 %     10.0 %     10.0 %     10.0 %     10.0 %
Zn Concentrate           wmt     1,028,845       140,137       162,594       157,146       154,345       135,305       116,384       109,149       53,786       -  
                                                                                             
Total Tonnes Concentrate           dmt     1,134,554       166,212       180,838       180,055       172,492       142,056       120,892       114,297       57,711       -  
Total Tonnes Concentrate           wmt     1,260,616       184,680       200,932       200,061       191,657       157,840       134,324       126,997       64,123       -  
                                                                                             
Total Recovered                                                                                            
Ag           oz     21,676,261       3,904,695       3,417,911       3,678,716       3,144,957       2,164,535       1,946,501       2,018,322       1,400,625       -  
Cu           tonnes     4,496       531       652       765       714       563       526       553       192       -  
Pb           tonnes     96,796       19,477       16,252       18,100       15,609       9,082       7,026       6,912       4,339       -  
Zn           tonnes     464,740       63,301       73,445       70,984       69,719       61,119       52,572       49,304       24,295       -  
                                                                                             
Metal Prices                                                                                            
LOM Ag           US$/oz   $ 17.20       19.05       17.11       16.95       16.40       16.40       16.87       16.87       16.87       16.87  
LOM Cu           US$/tonne   $ 6,388.29       6,071       6,137       6,277       6,351       6,639       6,627       6,627       6,627       6,627  
LOM Pb           US$/tonne   $ 1,977.29       1,950       1,898       1,957       2,039       2,247       1,910       1,910       1,910       1,910  
LOM Zn           US$/tonne   $ 2,511.20       2,219       2,298       2,539       2,720       2,928       2,449       2,449       2,449       2,449  
Au           US$/oz Au   $ 1,580.04     $ 1,901     $ 1,613     $ 1,553     $ 1,466     $ 1,466     $ 1,500     $ 1,500     $ 1,500     $ 1,500  
Ag           US$/oz Ag   $ 17.20     $ 19.05     $ 17.11     $ 16.95     $ 16.40     $ 16.40     $ 16.87     $ 16.87     $ 16.87     $ 16.87  
Cu           US$/lb Cu   $ 2.90     $ 2.75     $ 2.78     $ 2.85     $ 2.88     $ 3.01     $ 3.01     $ 3.01     $ 3.01     $ 3.01  
Pb           US$/lb Pb   $ 0.90     $ 0.88     $ 0.86     $ 0.89     $ 0.92     $ 1.02     $ 0.87     $ 0.87     $ 0.87     $ 0.87  
Zn           US$/lb Zn   $ 1.14     $ 1.01     $ 1.04     $ 1.15     $ 1.23     $ 1.33     $ 1.11     $ 1.11     $ 1.11     $ 1.11  
Exchange Rate     1.00 US$ = 1.00 C$     US$ 1.00 = X C$   $ 1.00     $ 1.00     $ 1.00     $ 1.00     $ 1.00     $ 1.00     $ 1.00     $ 1.00     $ 1.00     $ 1.00  
                                                                                             
Payable %                                                                                            
Cu Concentrate Payable %                                                                                            
Payable Ag Grade           oz/t     42.20       64.36       45.89       42.08       38.56       33.68       32.40       31.95       63.80       -  
Payable Cu     18.84 %   %             18.8 %     18.8 %     18.8 %     18.8 %     18.8 %     18.8 %     18.8 %     18.8 %     18.8 %
Pb Concentrate Payable %                                                                                            
Payable Ag Grade           oz/t     84.48       75.63       79.33       76.67       76.01       89.90       104.51       110.16       121.76       -  
Payable Pb     49.06 %   %             49.06 %     49.06 %     49.06 %     49.06 %     49.06 %     49.06 %     49.06 %     49.06 %     49.06 %
Zn Concentrate Payable %                                                                                            
Payable Ag Grade           oz/t     0.98       1.98       0.98       1.33       0.88       0.24       0.35       0.61       1.71       -  
Payable Zn           %             42.2 %     42.2 %     42.2 %     42.2 %     42.2 %     42.2 %     42.2 %     42.2 %     42.2 %
                                                                                             
Payable                                                                                            
Cu Concentrate Payables                                                                                            
Payable Ag           oz     956,429       172,288       150,810       162,317       138,766       95,507       85,886       89,055       61,800       -  
Payable Cu           tonnes     4,269       504       619       727       678       534       499       525       182       -  
Payable Ag           US$/t conc     725.88       1,226.0       785.2       713.3       632.3       552.4       546.6       539.1       1,076.3       -  
Payable Cu           US$/t conc     1,204       1,144       1,156       1,183       1,197       1,251       1,249       1,249       1,249       1,249  
Pb Concentrate Payables                                                                                            
Payable Ag           oz     15,706,690       2,829,355       2,476,629       2,665,610       2,278,846       1,568,429       1,410,441       1,462,483       1,014,898       -  
Payable Pb           tonnes     91,218       18,354       15,315       17,057       14,709       8,559       6,621       6,513       4,089       -  
Payable Ag           US$/t conc.     1,453       1,441       1,357       1,300       1,247       1,474       1,763       1,858       2,054       -  
Payable Pb           US$/t conc.     970       957       931       960       1,000       1,102       937       937       937       937  

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

19-5

 

 

    INPUTS   UNITS   TOTAL     2021 Year 1     2022 Year 2     2023 Year 3     2024 Year 4     2025 Year 5     2026 Year 6     2027 Year 7     2028 Year 8     2029 Year 9  
Zn Concentrate Payables                                                                                        
Payable Ag       oz     912       250       143       188       123       29       37       60       83       -  
Payable Zn       tonnes     390,663       53,212       61,738       59,670       58,606       51,377       44,192       41,445       20,423       -  
Payable Ag       US$/t conc.     17.17       38       16.7       22.5       14.5       4.0       5.9       10.2       28.9       -  
Payable Zn       US$/t conc.     1,059       936       970       1,071       1,148       1,235       1,033       1,033       1,033       1,033  
                                                                                         
e                                                                                        
Ag Gross Revenue       US$ '000   $ 286,605     $ 57,186     $ 44,958     $ 47,937     $ 39,651     $ 27,289     $ 25,244     $ 26,175     $ 18,165     $ 0  
Cu Gross Revenue       US$ '000   $ 27,274     $ 3,062     $ 3,800     $ 4,562     $ 4,306     $ 3,547     $ 3,310     $ 3,480     $ 1,209     $ 0  
Pb Gross Revenue       US$ '000   $ 180,365     $ 35,795     $ 29,069     $ 33,380     $ 29,992     $ 19,232     $ 12,646     $ 12,440     $ 7,811     $ 0  
Zn Gross Revenue       US$ '000   $ 981,034     $ 118,076     $ 141,875     $ 151,501     $ 159,409     $ 150,431     $ 108,227     $ 101,499     $ 50,016     $ 0  
Add Zn Gross Revenue - Intgr CJM       US$ '000   $ 176,872     $ 28,590     $ 25,864     $ 26,104     $ 25,308     $ 23,011     $ 20,013     $ 18,738     $ 9,243     $ 0  
Total Gross Revenue       US$ '000   $ 1,652,150     $ 242,709     $ 245,565     $ 263,484     $ 258,667     $ 223,509     $ 169,439     $ 162,333     $ 86,444     $ 0  
                                                                                         
Transport                                                                                        
Cu Concentrate   C$127.05 / wmt conc   US$ '000   $ 3,199     $ 378     $ 464     $ 545     $ 508     $ 400     $ 374     $ 393     $ 137     $ 0  
Pb Concentrate   C$123.84 / wmt conc   US$ '000   $ 25,585     $ 5,148     $ 4,296     $ 4,784     $ 4,126     $ 2,401     $ 1,857     $ 1,827     $ 1,147     $ 0  
Zn Concentrate   C$38.03 / wmt conc   US$ '000   $ 39,127     $ 5,329     $ 6,183     $ 5,976     $ 5,870     $ 5,146     $ 4,426     $ 4,151     $ 2,045     $ 0  
Treatment                                                                                        
Cu Concentrate   US$111.68 / dmt conc   US$ '000   $ 2,519     $ 249     $ 336     $ 411     $ 435     $ 334     $ 312     $ 328     $ 114     $ 0  
Pb Concentrate   US$201.68 / dmt conc   US$ '000   $ 37,909     $ 7,984     $ 6,493     $ 7,023     $ 6,056     $ 3,437     $ 2,659     $ 2,615     $ 1,642     $ 0  
Zn Concentrate   US$238.72 / dmt conc   US$ '000   $ 220,619     $ 36,510     $ 34,531     $ 32,793     $ 30,364     $ 26,180     $ 25,101     $ 23,540     $ 11,600     $ 0  
Refining cost                                                                                        
Ag in Pb   US$1.00 / oz   US$ '000   $ 15,654     $ 2,820     $ 2,468     $ 2,657     $ 2,271     $ 1,563     $ 1,406     $ 1,458     $ 1,012     $ 0  
Ag inCu   US$0.50 / oz   US$ '000   $ 478     $ 86     $ 75     $ 81     $ 69     $ 48     $ 43     $ 45     $ 31     $ 0  
Cu   US$0.08 / lb   US$ '000   $ 753     $ 89     $ 109     $ 128     $ 120     $ 94     $ 88     $ 93     $ 32     $ 0  
Pb   US$0.00 / lb   US$ '000   $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0  
Market Participation                                                                                        
Cu   NA   US$ '000   $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0  
Pb   NA   US$ '000   $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0  
Zn   NA   US$ '000   $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0  
Total Charges       US$ '000   $ 345,843     $ 58,593     $ 54,956     $ 54,398     $ 49,819     $ 39,603     $ 36,265     $ 34,450     $ 17,760     $ 0  
                                                                                         
Net Smelter Return       US$ '000   $ 1,306,307     $ 184,116     $ 190,609     $ 209,085     $ 208,848     $ 183,906     $ 133,174     $ 127,883     $ 68,684     $ 0  
Royalty NSR   Input Rate Into   US$ '000   $ 19,648     $ 2,920     $ 3,050     $ 4,008     $ 4,121     $ 2,731     $ 1,132     $ 1,091     $ 594     $ 0  
    Proforma                                                                                    
Net Revenue       US$ '000   $ 1,286,659     $ 181,196     $ 187,560     $ 205,077     $ 204,727     $ 181,175     $ 132,042     $ 126,792     $ 68,090     $ 0  
Unit NSR       US$/t milled   $ 92.90     $ 84     $ 84     $ 92     $ 101     $ 109     $ 96     $ 92     $ 85       #DIV/0!  
COST                                                                                        
                                                                                         
Mining (Underground)       US$/t milled   $ 32.81     $ 29.2     $ 29.0     $ 29.2     $ 30.4     $ 33.7     $ 37.4     $ 37.6     $ 51.5     $ 0.0  
Mine Development       US$/t milled   $ 6.56     $ 7.9     $ 7.2     $ 6.7     $ 6.4     $ 6.4     $ 6.3     $ 4.6     $ 5.4     $ 0.0  
Processing       US$/t milled   $ 12.72     $ 10.8     $ 10.6     $ 10.6     $ 11.3     $ 13.2     $ 15.2     $ 15.3     $ 24.1     $ 0.0  
G&A       US$/t milled   $ 7.30     $ 7.3     $ 7.3     $ 7.3     $ 7.3     $ 7.3     $ 7.3     $ 7.3     $ 7.3     $ 0.0  
Total Operating Cost       US$/t milled   $ 59.39     $ 55.2     $ 54.0     $ 53.7     $ 55.4     $ 60.5     $ 66.2     $ 64.8     $ 88.3     $ 0.0  
                                                                                         
Mining (Underground)       US$ '000   $ 454,350     $ 63,077     $ 64,320     $ 64,742     $ 61,913     $ 55,796     $ 51,610     $ 51,569     $ 41,323     $ 0  
Mine Deveopment       US$ '000   $ 90,887     $ 17,162     $ 15,971     $ 14,837     $ 13,065     $ 10,602     $ 8,673     $ 6,244     $ 4,332     $ 0  
Processing       US$ '000   $ 176,174     $ 23,274     $ 23,452     $ 23,446     $ 22,910     $ 21,808     $ 20,998     $ 20,972     $ 19,314     $ 0  
G&A       US$ '000   $ 101,109     $ 15,774     $ 16,219     $ 16,206     $ 14,861     $ 12,103     $ 10,076     $ 10,011     $ 5,858     $ 0  
Total Operating Cost       US$ '000   $ 822,519     $ 119,288     $ 119,961     $ 119,231     $ 112,750     $ 100,309     $ 91,356     $ 88,797     $ 70,827     $ 0  
Unit Operating Cost       US$/t milled   $ 84.36     $ 82.3     $ 78.7     $ 78.2     $ 79.9     $ 84.4     $ 92.5     $ 89.9     $ 110.4     $ 0.0  
                                                                                         
Other Costs       US$ '000   $ 10,624     $ 0     $ 0     $ 0     $ 2,981     $ 2,425     $ 2,015     $ 2,011     $ 1,192     $ 0  
                                                                                         
Operating Cashflow       US$ '000   $ 453,516     $ 61,908     $ 67,599     $ 85,846     $ 88,996     $ 78,441     $ 38,671     $ 35,983       -$3,929   $ 0  
              32.75       28.65       30.43       38.67       43.72       47.31       28.02       26.24       -4.90       0.00  
ST                                                                                        
Direct Cost                                                                                        
Mining       US$ '000   $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0  
Processing       US$ '000   $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0  
Infrastructure       US$ '000   $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0  
Tailings       US$ '000   $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0  
Total Direct Cost       US$ '000   $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0  

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

19-6

 

 

    INPUTS     UNITS   TOTAL     2021 Year 1     2022 Year 2     2023 Year 3     2024 Year 4     2025 Year 5     2026 Year 6     2027 Year 7     2028 Year 8     2029 Year 9  
Other Costs                                                                                            
EPCM / Owners / Indirect Cost     0 %   US$ '000   $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0  
Subtotal Costs           US$ '000   $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0  
                                                                                             
Contingency     0 %   US$ '000   $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0  
Initial Capital Cost           US$ '000   $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0  
                                                                                             
Sustaining Mine Development           US$ '000   $ 92,745     $ 17,170     $ 16,073     $ 16,941     $ 18,954     $ 13,124     $ 6,521     $ 1,934     $ 2,030     $ 0  
Mine Equipment           US$ '000   $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0  
Other Sustaining           US$ '000   $ 128,330     $ 32,807     $ 28,821     $ 33,722     $ 11,526     $ 12,858     $ 4,191     $ 4,405     $ 0     $ 0  
Working Capital           US$ '000   $ 0     $ 6,363     $ 307     $ 977     $ 204     -$ 852   -$ 2,374   -$ 228   -$ 2,572   -$ 1,825
Reclamation and closure           US$ '000   $ 25,196     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 0     $ 25,196  
Total Capital Cost           US$ '000   $ 246,271     $ 56,340     $ 45,201     $ 51,639     $ 30,683     $ 25,131     $ 8,338     $ 6,111     -$ 543   $ 23,371  
SH FLOW                                                                                            
Net Pre-Tax Cashflow           US$ '000   $ 207,245     $ 5,568     $ 22,398     $ 34,207     $ 58,313     $ 53,310     $ 30,333     $ 29,873     -$ 3,386   -$ 23,371
Cumulative Pre-Tax Cashflow           US$ '000           $ 5,568     $ 27,966     $ 62,173     $ 120,486     $ 173,796     $ 204,128     $ 234,001     $ 230,615     $ 207,245  
                                                                                             
Taxes - Income Tax           US$ '000   -$ 28,339   -$ 4,631   -$ 4,757   -$ 7,391   -$ 7,753   -$ 3,808   $ 0     $ 0     $ 0     $ 0  
Taxes - IEM/GEM           US$ '000   -$ 2,541   -$ 405   -$ 417   -$ 684   -$ 716   -$ 319   $ 0     $ 0     $ 0     $ 0  
                                                                                             
After-Tax Cashflow           US$ '000   $ 176,364     $ 532     $ 17,224     $ 26,132     $ 49,845     $ 49,182     $ 30,333     $ 29,873     -$ 3,386   -$ 23,371
Cumulative After-Tax Cashflow           US$ '000           $ 532     $ 17,756     $ 43,888     $ 93,733     $ 142,915     $ 173,248     $ 203,121     $ 199,735     $ 176,364  
                                                                                             
                                                                                             
ONOMICS                 mid-year period       0.5       1.5       2.5       3.5       4.5       5.5       6.5       7.5       8.5  
Pre-Tax IRR           %     N/A                                                                          
Pre-tax NPV at 7% discounting     7 %   US$ '000   $ 164,845     $ 5,384     $ 20,242     $ 28,891     $ 46,030     $ 39,328     $ 20,913     $ 19,249       -$2,039     -$13,153
Pre-tax NPV at 8% discounting     8 %   US$ '000   $ 159,759     $ 5,360     $ 19,962     $ 28,228     $ 44,557     $ 37,717     $ 19,871     $ 18,120       -$1,902     -$12,153
Pre-tax NPV at 9% discounting     9 %   US$ '000   $ 154,883     $ 5,335     $ 19,689     $ 27,586     $ 43,144     $ 36,186     $ 18,889     $ 17,067       -$1,775     -$11,238
After-Tax IRR           %     N/A                                                                          
After-Tax NPV at 7% discounting     7 %   US$ '000   $ 139,026     $ 515     $ 15,579     $ 22,102     $ 39,423     $ 36,374     $ 20,978     $ 19,319       -$2,048     -$13,216
After-Tax NPV at 8% discounting     8 %   US$ '000   $ 134,246     $ 512     $ 15,351     $ 21,565     $ 38,086     $ 34,797     $ 19,871     $ 18,120       -$1,902     -$12,153
After-tax NPV at 9% discounting     9 %   US$ '000   $ 130,143     $ 510     $ 15,151     $ 21,098     $ 36,938     $ 33,453     $ 18,937     $ 17,118       -$1,781     -$11,282

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

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19.2.1 Cash Flow Analysis

 

Mine economics have been evaluated using the discounted cash flow method, using mid-year discounting convention, and taking into account annual processed tonnages and copper, zinc, lead, and silver grades. The associated process recovery, copper, zinc, and lead concentrate grades, metal prices, operating costs, refining and transportation charges, royalties, and capital expenditures were also considered.

 

The economic analysis confirmed that the El Porvenir Mineral Reserves are economically viable. The pre-tax net present value (NPV) at an 9% base discount rate is US$155 million and the after-tax NPV at an 9% base discount is US$130 million.

 

The summary of the results of the cash flow analysis is presented in Table 19-2.

 

Table 19-2: Cash Flow Analysis 

Nexa Resources S.A. – El Porvenir Mine

 

Item

Discount Rate

Units

Value

Pre-tax NPV at 7% discount 7% US$ million 165
Pre-tax NPV at 8% discount 8% US$ million 160
Pre-tax NPV at 9% discount 9% US$ million 155
       
After-Tax NPV at 7% discount 7% US$ million 139
After-Tax NPV at 8% discount 8% US$ million 134
After-tax NPV at 9% discount 9% US$ million 130

 

The undiscounted pre-tax cash flow is US$207 million, and the undiscounted after-tax cash flow is US$177 million. For this cash flow analysis, the internal rate of return (IRR) and payback are not applicable as there is no negative initial cash flow (no initial investment to be recovered).

 

19.3 Sensitivity Analysis

 

Project risks can be identified in both economic and non-economic terms. Key economic risks were examined by running cash flow sensitivities on after-tax NPV at an 9% discount rate. The following items were examined:

 

Metal prices

 

Head grade

 

Metallurgical recovery

 

Operating costs

 

Capital costs

 

After-tax sensitivity over the base case has been calculated for -20% to +20% (for head grade), -10% to +5% (for recoveries), -20% to +20% (for metal prices), and -5% to +15% (operating costs and capital costs) variations to determine the most sensitive parameter of this project. The sensitivities are shown in Table 19-3 and Figure 19-1.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

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Table 19-3: After-Tax Sensitivity Analysis 

Nexa Resources S.A. – El Porvenir Mine

 

 

Head Grade

NPV at 9%
(US$ million)

80% Cu:0.18% Zn:3.00% Pb:0.71% Ag:50.24 g/t -33
90% Cu:0.20% Zn:3.37% Pb:0.80% Ag:56.52 g/t 57
100% Cu:0.23% Zn:3.75% Pb:0.88% Ag:62.8 g/t 130
110% Cu:0.25% Zn:4.12% Pb:0.97% Ag:69.8 g/t 202
120% Cu:0.27% Zn:4.50% Pb:1.06% Ag:75.4 g/t 270

 

 

Net Average Recovery (all metals)

NPV at 9%
(US$ million)

90% 81% 57
98% 85% 94
100% 90% 130
103% 92% 148
105% 94% 166

 

 

Metal Prices

NPV at 9%
(US$ million)

80% Cu:$2.32/lb Zn:$0.91/lb Pb:$0.72/lb Ag:$13.76/oz -77
90% Cu:$2.61/lb Zn:$1.03/lb Pb:$0.81/lb Ag:$15.48/oz 40
100% Cu:$2.90/lb Zn:$1.14/lb Pb:$0.90/lb Ag:$17.20/oz 130
110% Cu:$3.19/lb Zn:$1.25/lb Pb:$0.99/lb Ag:$18.92/oz 215
120% Cu:$3.48/lb Zn:$1.37/lb Pb:$1.08/lb Ag:$20.64/oz 294

 

 

Operating Costs (US$ million)

NPV at 9%
(US$ million)

95.0% 781 152
97.5% 802 141
100.0% 823 130
107.5% 884 97
115.0% 946 64

 

 

Total Capital Costs (US$ million)

NPV at 9%
(US$ million)

95.0% 234 140
97.5% 240 135
100.0% 246 130
107.5% 264 116
115.0% 283 101

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

19-9

 

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Figure 19-1: After-Tax NPV Sensitivity Graph

 

The after-tax NPV is most sensitive to metal prices, then to head grade, followed by metallurgical recoveries, operating costs, and capital costs.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

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20.0 Adjacent Properties

 

El Porvenir is situated adjacent to the Atacocha mining operation. The Atacocha property consists of 147 concessions covering approximately 2,872.5 ha and a processing plant (RPA, 2019). The mining site consists of 1,343.0 ha, and other surface property includes the TSF, accommodations, and other ancillary infrastructure. Atacocha is a polymetallic mining operation that consists of the Atacocha underground mine, the San Gerardo open pit, and the Chicrin 2 processing plant, which has a 4,500 tpd capacity. Atacocha is wholly owned by Nexa Resources Atacocha S.A.A. (formerly Compañía Minera Atacocha), in which Nexa Peru has a 66.62% equity interest. Nexa directly and indirectly owns 80.24% of the latter company. Table 20-1 presents Atacocha’s production from 2018 to 2020.

 

Table 20-1: Production - Atacocha Mine 

Nexa Resources S.A. – El Porvenir Mine

 

    YE 2020   YE 2019   YE 2018
Treatment ore (in tonnes)   1,065,363   1,505,428   1,551,472
Average ore grade            
Zinc (%)   1.20   1.43   1.43
Copper (%)   0.05   0.08   0.10
Lead (%)   1.15   1.30   1.18
Silver (ounces per tonne)   1.39   1.52   1.42
Gold (ounces per tonne)   0.01   0.01   0.02
Metal contained in concentrate production            
Zinc (in tonnes)   9,614   16,668   17,323
Copper (in tonnes)   0   40   125
Lead (in tonnes)   10,210   16,464   15,595
Silver (in oz)   1,184,750   1,882,138   1,678,920
Gold (in oz)   6,260   9,306   15,431
Cash cost, net of by-product credits (in US$/t)   17.8   1,052.0   1,115.5
Cash cost, net of by-product credits (in US$/lb)   0.8   0.48   0.51
Capital expenditures (in millions of US$)   15.3   11.8   16.9
             

Source: Nexa, 2020g

  

Together, El Porvenir and Atacocha form the Cerro Pasco Mining Complex. In 2013, Nexa initiated a project to integrate the two mines to streamline their operations, which has included the following areas:

 

Administrative functions

 

TSF

 

Electric power supply

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

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As indicated in Figure 20-1, El Porvenir is surrounded by other mineral properties. The following companies that hold properties in the vicinity are subsidiaries of the Volcan Group:

 

Compañía Minera Vichaycocha

 

Empresa Exploradora de Vinchos

 

Empresa Minera Paragsha

 

Minera San Sabastián AMC S.C.R.L.

 

The Volcan Group operates the Cerro de Pasco Mine in the nearby city of Cerro de Pasco. Nexa maintains a group of mining concessions located within the boundaries of some of the Volcan Group’s properties.

 

Other local property holders include:

 

Sociedad Minera El Brocal

 

David Prospero Rudas y otros

 

Corporación Minera Centauro S.A.C. (Centauro)

 

Centauro is a Peruvian capital corporation that focuses on exploration, mining, and processing of polymetallic minerals, such as gold, silver, and copper.

 

SLR has not independently verified this information and this information is not necessarily indicative of the mineralization at El Porvenir.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

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Figure 20-1: Mining Concessions in the Vicinity of El Porvenir

  

Source: Nexa, 2020

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

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21.0 Other Relevant Data and Information

 

No additional information or explanation is necessary to make this Technical Report Summary understandable and not misleading.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

 

 

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22.0 Interpretation and Conclusions

 

SLR has the following conclusions by area.

 

22.1 Geology and Mineral Resources

 

As of December 31, 2020, exclusive of Mineral Reserves, Measured Mineral Resources are estimated to total 0.23 Mt at 2.59% Zn, 0.99% Pb, 0.23% Cu, and 63.46 g/t Ag and Indicated Mineral Resources are estimated to total 1.33 Mt at 2.93% Zn, 0.89% Pb, 0.20% Cu, and 63.33 g/t Ag. In addition, Inferred Mineral Resources are estimated to total 8.47 Mt at 3.60% Zn, 0.95% Pb, 0.23% Cu, and 78.37 g/t Ag.

 

El Porvenir has features of skarn, hydrothermal vein/breccia-style, and stratabound deposits.

 

The control of mineralization is lithological, mineralogical, and structural.

 

Protocols for drilling, sampling, analysis, verification, and security meet industry standard practices. The drill hole database was verified by SLR and is suitable for Mineral Resource estimation.

 

The geological models are reasonably constructed using available geological information and are appropriate for Mineral Resource estimation.

 

The assumptions, parameters, and methodology used for the El Porvenir Mineral Resource estimate are appropriate for the style of mineralization and proposed mining methods.

 

Nexa’s exploration strategy, practices, and procedures are in line with industry standards.

 

A number of polymetallic prospects located near the deposits have been outlined and warrant additional exploration.

 

22.2 Mining and Mineral Reserves

 

As of December 31, 2020, Proven and Probable Mineral Reserves are estimated to total 13.85 Mt at 3.75% Zn, 0.88% Pb, 0.23% Cu, and 63 g/t Ag.

 

The assumptions, parameters, and methodology used for the El Porvenir Mineral Reserve estimate meet industry standard practices and are appropriate for the style of mineralization and proposed mining methods.

 

Most of El Porvenir’s ore production comes from mechanized C&F, which has proven to be an effective method for mining its deposits for decades. An increasing share of the Mine’s production comes from SLS in those areas that are suitable for the method. SLS is a lower-cost method than C&F, and provides an efficient means for disposing of development waste. According to the LOM plan, SLS’s share of El Porvenir’s output will increase from approximately 16% in 2021 to 46% in 2025.

 

22.3 Mineral Processing

 

Test work has been conducted in order to produce a geometallurgical model to predict metallurgical response during future processing at El Porvenir and relationships based on the ore source at El Porvenir having been derived to predict throughput, grinding media consumption, recovery, and concentrate quality.

 

 

Nexa Resources S.A. | El Porvenir Mine, SLR Project No: 233.03259.R0000

Technical Report Summary - January 15, 2021

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Review of historical production indicates that recoveries of copper, lead, and zinc are related to their head grades, while the majority of silver is recovered to the lead concentrate.

 

Average LOM planned head grades of zinc and copper are forecast to be similar to or higher than average head grades for the past three years, while the average planned lead head grade is forecast to decrease slightly compared to recent head grades. Forecast recoveries are in line with those achieved in recent years.

 

No fundamental changes to the concentrator feed are anticipated, and in the SLR QP’s opinion, based on recent processing plant performance, the forecast recoveries and concentrate qualities for the near future are reasonable.

 

22.4 Environmental, Permitting and Social Considerations

 

No environmental issues were identified from the documentation available for review that could materially impact the ability to extract the Mineral Resources and Mineral Reserves. The El Porvenir operation complies with applicable Peruvian permitting requirements. The approved permits address the authority’s requirements for operation of the underground mine, TSFs, WRDs, concentrator plant, water usage, and effluents discharge.

 

The monitoring program at El Porvenir includes meteorology, air quality, non-ionized radiation, noise, surface water quality, groundwater quality (only one location), spring water quality, effluent discharges, fauna and flora, and TSF physical stability. El Porvenir reports the results of its monitoring program to the authorities according to the frequency stated in the approved resolutions. SLR is not aware of any non-compliance issues raised by the authorities.

 

In the SLR QP’s opinion, the Environmental Management Plan for El Porvenir is adequate to address potential issues related to environmental compliance. A recommendation has been provided regarding the groundwater quality monitoring program (see Section 23.4).

 

Nexa utilizes an Integrated Dam Management System (referred to as SIGBar) for the El Porvenir TSF, which provides guidelines for document management, monitoring, evaluation, risk analysis, compliance with standards and legislation, training of personnel, operation of structures and other provisions.

 

The safety of operating a centerline raised tailings dam depends on the ability to maintain wide tailings beaches and a low phreatic level in the dam shell for stability. No issues with regard to crest settlements were noted in recent dam safety monitoring reports. SLR notes, however, that bedrock foundation grouting of the left and right abutments carried out in 2015 observed very significant grout takes in numerous grouthole stages indicating the filling of voids. A series of seepage collection sub-drainage pipes were also installed on the downstream shell of the dam prior to raising the rockfill to crest elevation 4,056 MASL. The dam monitoring consists of instrument measurements and field inspections.

 

A Mine Closure Plan has been developed for all the Mine components within the context of Peruvian legislation and is periodically updated. The most recent modification to the Mine Closure Plan and update to the closure cost estimate are from January 2020.

 

SLR’s social review indicates that, at present, Nexa’s operations at El Porvenir are a positive contribution to sustainability and community well-being. Nexa has established and continues to implement its various corporate policies, procedures, and practices in a manner consistent with relevant IFC Performance Standards. Nexa has, and continues to make, a positive contribution to the communities most affected by the site operations and has done a thorough job in documenting potential effects on stakeholders and protecting the rights, health, and safety of its employees.

 

 

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In the SLR QP’s opinion the grievance mechanism in place and the Community Relations Plan, in combination with Nexa’s Social Management Policy and Nexa’s Management Procedures on negotiation for land access, monitoring of social commitments, management of social crisis, promotion of local hiring, and communication with stakeholders, are adequate to address potential issues related to local communities.

 

Nexa established commitments with the communities San Juan de Milpo and San Francisco de Asis de Yarusyacan to employ direct and indirect local workforce, dependent on employment opportunities required by the mine operations for qualified and non-qualified workforce.

 

22.5 Costs and Economic Analysis

 

The LOM operating cost forecast reflects the existing operating status of the Mine. The SLR QP has reviewed recent operating costs and is of the opinion that the forecast is appropriate for the El Porvenir operation. Nexa also continue to assess operating efficiencies and approaches in efforts to improve operating costs in the different cost centres.

 

The economics of the El Porvenir operation are positive over the LOM, confirming that the Mineral Reserves are economically viable. The economic analysis shows an after-tax NPV, at an 9% base discount rate, of $130 million.

 

 

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23.0 Recommendations

 

SLR has the following recommendations by area.

 

23.1 Geology and Mineral Resources

 

1. Improve the reconciliation processes by implementing a formal procedure and forming a multi-disciplinary team to organize and analyze reconciliation results so that production data can be used to calibrate future resource and reserve models.

 

2. Divide mineralization domains where groups of wireframes have been merged to avoid sharing of samples.

 

3. Review the inclusion of additional grade domains considering spatial and statistical correlations, to prevent smearing of high grades into low grade areas and vice versa.

 

4. Update the 2018 lithological model and build a litho-structural model with the main lithologies and faults that are controlling the mineralization to help define the geometry and boundaries of the mineralization. An updated lithological model would also be beneficial to evaluate and define density values by rock and by domain.

 

5. Until there is a well-established reconciliation process, monitor the silver and lead grades in the model with grade control and head grade to calibrate capping values and confirm if the higher silver and lead capping values are appropriate.

 

6. Investigate if capping levels should be applied based on high grade and low grade domains for zinc, lead, copper, and silver.

 

7. Increase the number of density samples in areas that currently have insufficient density tests available.

 

8. Use the production data to monitor the chosen drill spacing for the minor continuity zones to determine if sufficient confidence is provided to support detailed mine planning, as these domains show less grade and geological continuity.

 

9. Review and adjust resource and reserve shapes to follow the mineralization trend. Currently, there are a small number of shapes that do not follow the mineralization trend.

 

10. Re-evaluate some of the zones that were not included in the Mineral Resources and Mineral Reserves, on an ongoing basis, to potentially include part of these tonnes with continuous blocks that have the potential to be recoverable, to generate resource shapes and possibly reserve stopes.

 

11. Document all the supporting data used to define non-recoverable solids and document any changes.

 

12. Improve the survey accuracy of the mineralized mined-out stopes and development to guide the mineralization solid geometries and trends, and clean up the mined-out solids, particularly, overlapping areas.

 

13. Complete the 2021 exploration program, consisting of a 18,000 m drill program to define new Inferred Resources. The 2021 exploration program budget is approximately US$3.1 million.

 

 

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23.2 Mining and Mineral Reserves

 

1. Consider upgrading the Mine’s underground communication system by replacing the present leaky-feeder system with a high speed digital network based on Wi-Fi or LTE technology. The upgrade would permit implementing the following:

 

Centralized control and monitoring of underground operations from a control room on surface, including real-time tracking of personnel and equipment, telemetry, VOD, seismic monitoring, and closed-circuit television, among other applications.

 

Automated and tele-remote technology to operate equipment from control stations on surface for mucking development headings during shift changes, crushing, and operating rockbreakers, among other applications.

 

2. As the Mine has extensive existing workings, a private 4G-LTE network could be an attractive option. A private 4G-LTE network can provide substantial level coverage with a lower installation requirement than alternative systems as it sends a reliable signal over long distances without coaxial cables, amplifiers, or access points. Furthermore, it is not limited to line-of-site transmission.

 

23.3 Mineral Processing

 

1. Evaluate the potential benefits that may be derived from a geometallurgical model to determine whether additional test work and further development of a geometallurgical model will provide more valuable information than what is already available from test work results.

 

23.4 Environmental, Permitting and Social Considerations

 

1. Due to uncertainty regarding the potential for acid generation of the waste rock, geochemical evaluation (including static and kinetic geochemical testing on waste rock samples) should be carried out prior to closure to inform closure planning and water quality predictions for post-closure. Water quality monitoring should continue during operations to verify compliance with the national environmental standards and the appropriateness of the waste rock disposal and water management procedures that are in place.

 

2. Expand the groundwater quality monitoring program to include additional stations for collection of groundwater quality samples (and subsequent analysis). At a minimum, consideration should be given to the installation of one station upstream of the El Porvenir site.

 

3. Implement a water balance for ongoing operations to be updated by Mine personnel using meteorological and water monitored data on a regular basis (at least monthly). The water balance is an important tool to track trends and conduct short term predictions through simulation of variable operating and/or climatic scenarios to support decision making associated with tailings pond operation (e.g., maintaining adequate freeboard at all times).

 

4. Develop an integrated water balance that reflects the interaction between the El Porvenir and Atacocha operations from a water balance perspective to identify and predict possible scenarios of interruption of mine operations due to water management issues and/or dam safety concerns (e.g., not maintaining adequate dam freeboard).

 

5. Investigate opportunities for optimization of construction, tailings deposition, and water management between the Atacocha and El Porvenir operations in order to prevent situations where potential problems with one of the tailings dams could impact continuity of the sister operation.

 

 

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6. The following recommendations are proposed for the TSF:

 

Classification of the TSF in terms of the Global Tailings Standard or the Canadian Dam Association. The classification may require more conservative design criteria in terms of flood management and seismic loading.

 

A dam breach analysis to inform the TSF classification and emergency preparedness plan.

 

A TARP for the piezometers for inclusion in the monitoring plan.

 

Capacity assessments of the TSF completed on a bi-annual basis with topographic and bathymetric surveys.

 

Complete long term geochemical kinetic testing of the tailings.

 

Implement a groundwater monitoring program at the TSF to determine levels of metals and sulphates.

 

Monitor the water quality from the TSF subsurface drains.

 

23.5 Costs and Economic Analysis

 

1. Continuously monitor costs and lock in costs as soon as possible to eliminate economic uncertainty.

 

2. Continue efforts towards improving efficiencies and approaches to mining and development operations as opportunities arise in these areas.

 

 

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24.0 References

 

Amphos 21 Consulting Perú S.A.C., 2013-2019:

 

El Porvenir: Estudio Hidrogeológico Preliminar para - Profundización del Pique Picasso, prepared for Compañía Minera Milpo S.A., December 2016.

 

UM El Porvenir: Análisis Hidrogeológico para Estimación de Caudales durante la Construcción del Pique Winze, prepared for Compañía Minera Milpo S.A., October 2014.

 

UM El Porvenir: Análisis Hidrogeológico para Estimación de Caudales durante la Construcción del Pique Winze, prepared for Compañía Minera Milpo S.A., October 2014.

 

Modificación del Estudio de Impacto Ambiental de la UM Atacocha - Estudio Hidrológico e Hidrogeológico, prepared for Compañía Minera Milpo S.A., July 2018.

 

Estudio Hidrogeológico y Soporte a Balance Hídrico para el Recrecimiento Presa de Relaves El Porvenir hasta la Cota 4,100 msnm, El Porvenir Mine, prepared for Compañía Minera Milpo S.A., August 2019.

 

Ausenco Vector, 2013, Ingeniería de Detalle para el Crecimiento de la Presa de Relaves El Porvenir, Anexo F – Caracterización Geoquí0ica del Relave Cicloneado, Report No. J09.82.12.03 Rev. 0 prepared for Compañía Minería Milpo S.A.A., February 2013.

 

Ausenco, 2016a: Milpo Andina Perú S.A.C. Ingeniería de Detalle Recrecimiento del Dique El Porvenir – Cota 4056. Report No. 101521-01-RPT-005 Rev. B, prepared for Compañía Minería Milpo S.A.A., August 2016.

 

Ausenco, 2016b: Milpo Andina Perú S.A.C. Ingeniería de Detalle del Recrecimiento de la Presa de Relaves El Porvenir – Cota 4100. Report No. 101521-01-RPT-002 Rev. 0, prepared for Compañía Minería Milpo S.A.A., August 2016.

 

Ausenco, 2018: Milpo Andina Perú S.A.C. Ingeniería de Detalle Recrecimiento del Dique El Porvenir – Cota 4064. Report No. 102378-01-RPT-004 Rev. 1, prepared for Compañía Minería Milpo S.A.A., September 7, 2018.

 

Ausenco, 2020: Compañía Minera Atacocha S.A.A. Ingeniería de Detalle del Recrecimiento de la Relavera Atacocha desde la Cota 4110 a la Cota 4128. Report No. 102377-01-RPT-006 Rev. 0, prepared for Compañía Minera Atacocha S.A.A., March 17, 2020.

 

Bardales, M., 2020, Legal Opinion on Section 4 of Technical Report (Memo), Nexa Resources, August 16, 2020.

 

Baumgartner, R., Fontboté, L., and Vennemann, T., 2008, Mineral Zoning and Geochemistry of Epithermal Polymetallic Zn-Pb-Ag-Cu-Bi Mineralization at Cerro de Pasco. Economic Geology, Vol. 103, pp 493-537.

 

Benavides-Caceres, V.,1999, Orogenic Evolution of the Peruvian Andes. in Geology and Ore Deposits of the Central Andes, Soc. Econ. Geo. Special Pub. No. 7, Skinner, B.J. (Ed), pp. 61-107.

 

 

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Calixto, F., 2020, Evaluación del Peligro Sísmico en U. M. El Porvenir, Institute of Mine Seismology, December 24, 2020.

 

Canadian Institute of Mining, Metallurgy and Petroleum (CIM), 2014, CIM Definition Standards for Mineral Resources and Mineral Reserves, adopted by the CIM Council on May 10, 2014.

 

Clark, A.H., Farrar, E., Kontak, D.J., Langridge, R.J., Arena, F., Francem L.J., McBride, S.L., Woodman, P.L., Wasteneys, H.A., Sandeman, H.A. and Archibald, D.A., 1990, Geologic and Geochronological Constraints on the Metallogenic Evolution of the Andes of Southern Peru. Econ. Geo., Vol. 85, pp. 1520-1583.

 

Cesel Ingenieros, 2011, Modificación del EIA para la Ampliación de la Capacidad Instalas a 7,500 TMD Unidad Minera El Porvenir, prepared for Compañía Minería Milpo S.A.A., December 2011.

 

Climaco, R., 2020, Market Assumptions (Memo), Nexa Resources, October 2020

 

Cobeñas, B.G.R., 2008, Cinturonas metalogénicos cenozoicos en Pasy y Huánuco: tipos de yacimientos y naturaleza geoquímica de los magmas asociados: Universidad Nacional Mayor do San Marcos, Facultad de Ingeniera Geologica, Minera, Metalurgica y Geografica, Tesis, 75 p.

 

De Pinha Taranto, 2020, D., Smelter Terms (Memo), Nexa Resources, October 2020.

 

Ecotec, 2018, Quinto Informe Técnico Sustentatorio (ITS) para la Modificación de Componentes Auxiliares de la Unidad Minera El Porvenir, Report No. 290463-200-103-INF-001 Rev. 1 prepared for Nexa Resources El Porvenir S.A.C., December 4, 2018.

 

Ellison, R.A., Klink, B.A., and Hawkins, 1989, Deformation events in the Andean cycle in the Altiplano and Western Cordillera, southern Peru. Journal of South American Earth Sciences, Vol. 3 pp. 263-276.

 

Engler, A., 2009, The Geology of South America. GEOLOGY Vol. IV, pp. 374-405.

 

Escegis, 2020, Sexto Informe Técnico Sustentatorio de la Unidad Minera El Porvenir, prepared for Nexa Resources El Porvenir S.A.C., January 2020.

 

Form 20-F for fiscal year ended December 31, 2019 for Nexa Resources S.A., United States Securities and Exchange Commission, filed March 20, 2020.

 

Form 20-F for fiscal year ended December 31, 2018 for Nexa Resources S.A., United States Securities and Exchange Commission, filed April 3, 2019.

 

Geoconsultoria, 2020, Formulario De Registro De Inspección (FRI), April 28, 2020.

 

Geoconsultoria, 2018, Nexa, El Porvenir, Presa de relaves - Evaluación Anual de Seguridad - 2017 MP05RT09 Rev. 0, January 2018.

 

 

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Gilbert, J.M., and Lowell, J.D., 1974, Variations in zoning patterns pattern in porphyry ore deposits: Can. Inst. Mining Metall., v. 67, no. 742, pp. 99-104.

 

Global Mining Guidelines Group (GMG), 2018, Underground Mine Communications Infrastructure Guidelines, Part III: General Guidelines, version date September 21, 2018.

 

Hammarstrom, J.M., Kotlyar, B.B., Theodore, T.G., Elliott, J.E., John, D.A., Doebrich, J.L., Nash, J.T., Carlson, R.R., Lee, G.K., Livo, K.E., and Klein, D.P., 1991, Cu-Au and Zn-Pb Skarn Deposits: U.S. Geological Survey Open File Report 95-0831, Ch. 12, pp. 90-111.

 

Klohn Crippen Berger (KCB), 2006, Plan de Cierre Conceptual de la U.E.A. Milpo No. 1, prepared for Compañía Minería Milpo S.A.A., August 16, 2006.

 

KCB, 2020, Tercera Modificación de Plan de Cierre El Porvenir, Report No. ZC1365A01 prepared for Nexa Resources El Porvenir S.A.C., January 2020.

 

Mégard, F., 1968, Geologia de Cuadrángulo de Huandayo: Boletin del Servicio de Geologia y Mineria 18, 123p.

 

Nexa Resources S.A., 2019a, Corporate Policies.

 

Nexa Resources S.A., 2019b, Informe de Validación de Base de Datos Atacocha.

 

Nexa Resources, 2019c, Estudio Geomecánico de Implementación de la Cartilla Geomecánica de Sostenimiento, Prepared by the Departamento De Geomecánica, El Porvenir Mine, August 2019.

 

Nexa Resources S.A., 2020a, An Internal legal opinion by Magaly Bardales, Legal Corporate Manager and Institutional Affairs, Nexa, a letter to RPA expressing an opinion on Section 4 content of Technical Report (August 16, 2020).

 

Nexa Resources S.A., 2020b, Reporte de Recursos Minerales U.M. El Porvenir, Pasco, Peru, Reporte Interno (July 22, 2020).

 

Nexa Resources S.A., 2020c, Estudio de la Vida Útil da estrutura: Barragem de Relaves de la Unidad El Porvenir.

 

Nexa Resources S.A., 2020d, Plan de minado 2020 El Porvenir, including:

 

Ventilación El Porvenir (Memo),

 

Sistema de drenaje y bombeo (Memo)

 

Relleno hidráulico (Memo)

 

Sistema de suministro de energía eléctrica (Memo)

 

Marketing and Metal Price Assumptions (Memo)

 

Smelter Terms and Concentrate Marketing (Memo)

 

Nexa Resources S.A., 2020e, Informe Anual – Aseguramiento y Control de Calidad 2020.

 

 

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Nexa Resources S.A., 2020f: Market Intelligence team, Industry Scenario 2020 – Supply and Costs presentation (July 2020).

 

Nexa Resources S.A., 2020g: Form 20-F for fiscal year end December 31, 2019 filed with United States Securities and Exchange Commission

 

Nexa Resources S.A., 2020h, Geotechnical Studies, including:

 

Analisis de Estabilidad para la Aplicación del Metodo de Minado Sub Level Stoping en la Veta CN-03 Nv. -890/-910, El Porvenir Mine, April 15, 2020.

 

Analisis de Estabilidad para la Aplicación del Metodo de Minado Sub Level Stoping en la Veta Carmen Cola Nv. 3470/3450., El Porvenir Mine, December 14, 2020.

 

Determinación del Pilar Veta Éxito NV. 3550 (Rib Pillar), El Porvenir Mine September 2020.

 

Determinación de la Longitud Maxima Abierta para El Minado SLS de la Veta Éxito NV. 3370, El Porvenir Mine, May 2020.

 

Determinación del Pilar Corona para el Minado del Stope Porvenir 3 – Zona Alta, El Porvenir Mine, March 2020.

 

Nexa Resources S.A., 2021, Estudio Geomecánico Cuerpo Don Ernesto, El Porvenir Mine, January 2021.

 

Peterson, U., 1999, Magmatic and metallogenic evolution of the Central Andes. In Geology and ore deposits of the Central Andes (Skinner, B.; editor). Society of Economic Geology, Special Publication, No. 7, pp. 109-153.

 

Roscoe Postle Associates Inc. (RPA), 2019: Technical Report on the Atacocha Mine, Pasco Province, Central Peru, a NI 43-101 Technical Report prepared for Nexa Resources S.A., March 22, 2019.

 

Saez, F. et al, 2017, Independent Technical Report pursuant to NI 43-101 of Canadian Sec. Admin. For El Porvenir Mine, Peru, SRK Consulting (Peru) S.A., effective date June 30, 2017.

 

Schlumberger Water Services, 2012, Actualización de Plan de Cierre de Minas Unidad Minera El Porvenir (U.E.A. Milpo No. 1), Report No. 51739 prepared for Compañía Minería Milpo S.A.A., June 2012.

 

Soler and Bonhomme, 1988: Oligocene magmatic activity and associated mineralization in the polymetallic belt of central Peru. Economic Geology, 83(3), 657-663.

 

SRK Consulting (Peru) S.A., 2017, Independent Technical Report pursuant to National Instrument 43-101 of the Canadian Securities Administrators for El Porvenir Mine, Perú, prepared for VM Holding S.A., filed on SEDAR/ available at www.sedar.com (August 15, 2017).

 

Stuart, L., 2020, Getting the message across, CIM Magazine.

 

Transmin Metallurgical Consultants, 2018, Estudio Geometalúrgico Preliminar para Unidad Minera El Porvenir, prepared for Nexa Resources S.A. (June 15, 2018).

 

 

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Transmin Metallurgical Consultants, 2019, Estudio Geometalúrgico Fase 2 para Unidad Minera El Porvenir, prepared for Nexa Resources Peru S.A. (April 29, 2019).

 

Transmin Metallurgical Consultants, 2020, Estudio Geometalúrgico Fase 3 para Unidad Minera El Porvenir, prepared for Nexa Resources Peru S.A. (May 18, 2020).

 

US Securities and Exchanges Commission, 2018: Regulation S-K, Subpart 229.1300, Item 1300 Disclosure by Registrants Engaged in Mining Operations.

 

US Securities and Exchange Commission, Form 20-F Nexa Resources S.A., for fiscal year end December 31, 2019.

 

 

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25.0 Reliance on Information Provided by the Registrant

 

This report has been prepared by SLR for Nexa. The information, conclusions, opinions, and estimates contained herein are based on:

 

Information available to SLR at the time of preparation of this report,

 

Assumptions, conditions, and qualifications as set forth in this report, and

 

Data, reports, and other information supplied by Nexa and other third party sources.

 

For the purposes of the Summary and Section 3 of this Technical Report Summary, SLR has relied on ownership information provided in an internal legal opinion by Magaly Bardales, Legal Corporate Manager and Institutional Affairs dated August 16, 2020 (Nexa, 2020a). SLR has not researched property title or mineral rights for the El Porvenir Mine as we consider it reasonable to rely on Nexa’s legal counsel who is responsible for maintaining this information.

 

SLR has relied on Nexa for guidance on applicable taxes, royalties, and other government levies or interests, applicable to revenue or income from the Mine in the Summary and Section 19. As the Mine has been in operation for over ten years, Nexa has considerable experience in this area.

 

The Qualified Persons have taken all appropriate steps, in their professional opinion, to ensure that the above information from Nexa is sound.

 

Except for the purposes legislated under provincial securities laws, any use of this report by any third party is at that party’s sole risk.

 

 

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26.0 Date and Signature Page

 

This report titled “Technical Report Summary on the El Porvenir Mine, Department of Pasco, Peru” with an effective date of December 31, 2020 was prepared and signed by:

 

SLR Consulting (Canada) Ltd. (Signed) SLR Consulting (Canada) Ltd.
   
Dated at Toronto, ON  
January 15, 2021  

 

 

 

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Exhibit 15.3

 

 

 

 

 

 

 

Technical Report Summary on the Vazante Polymetallic Operations, Minas Gerais, Brazil

 

SLR Project No: 233.03245.R0000

 

Prepared by

SLR Consulting (Canada) Ltd.

55 University Ave., Suite 501

Toronto, ON M5J 2H7

for

 

Nexa Resources S.A.

Rua Guaicuí, 20 - 14° Andar

Belo Horizonte, Minas Gerais

30380-380

 

Effective Date – December 31, 2020

Signature Date - February 15, 2021

 

FINAL

 

Distribution: 1 copy – Nexa Resources S.A.
1 copy – SLR Consulting (Canada) Ltd.

 

 

 

 

 

 

 

 

Contents

 

1.0 Executive Summary 1-14

 

1.1 Summary 1-14

 

1.2 Economic Analysis 1-20

 

1.3 Technical Summary 1-23

 

2.0 Introduction 2-1

 

2.1 Site Visits 2-1

 

2.2 Sources of Information 2-1

 

2.3 List of Abbreviations 2-3

 

3.0 Property Description 3-1

 

3.1 Location 3-1

 

3.2 Land Tenure 3-3

 

3.3 Encumbrances 3-13

 

3.4 Royalties 3-13

 

4.0 Accessibility, Climate, Local Resources, Infrastructure and Physiography 4-1

 

4.1 Accessibility 4-1

 

4.2 Climate 4-1

 

4.3 Local Resources 4-1

 

4.4 Infrastructure 4-1

 

4.5 Physiography 4-2

 

5.0 History 5-1

 

5.1 Prior Ownership 5-1

 

5.2 Exploration and Development History 5-1

 

5.3 Historical Resource Estimates 5-6

 

5.4 Past Production 5-6

 

6.0 Geological Setting, Mineralization, and Deposit 6-1

 

6.1 Regional Geology 6-1

 

6.2 Local Geology 6-4

 

6.3 Property Geology 6-8

 

6.4 Hydrothermal Alteration 6-14

 

6.5 Mineralization 6-16

 

6.6 Deposit Descriptions 6-18

 

6.7 Deposit Types 6-26

 

7.0 Exploration 7-1

 

7.1 Exploration 7-1

 

 

 

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7.2 Drilling 7-20

 

7.3 Geotechnical and Hydrogeology 7-42

 

8.0 Sample Preparation, Analyses, and Security 8-1

 

8.1 Sample Preparation and Analysis 8-1

 

8.2 Quality Assurance and Quality Control (QA/QC) 8-5

 

9.0 Data Verification 9-1

 

10.0 Mineral Processing and Metallurgical Testing 10-1

 

10.1 Summary 10-1

 

10.2 Recent Test Work 10-1

 

10.3 Current Performance 10-5

 

10.4 Deleterious Elements 10-5

 

11.0 Mineral Resource Estimates 11-1

 

11.1 Summary 11-1

 

11.2 Hypogene Mineralization (Willemite) 11-3

 

11.3 Supergene Mineralization (Calamine) 11-58

 

11.4 Aroeira Tailings 11-90

 

12.0 Mineral Reserve Estimates 12-1

 

12.1 Summary 12-1

 

12.2 Dilution 12-2

 

12.3 Mining Extraction 12-3

 

12.4 Geotechnical and Hydrological Studies 12-4

 

12.5 Cut-Off Value 12-10

 

12.6 Reconciliation 12-12

 

13.0 Mining Methods 13-1

 

13.1 Mine Design 13-1

 

13.2 Mining Method 13-3

 

13.3 Life of Mine Plan 13-9

 

13.4 Infrastructure 13-11

 

13.5 Mine Equipment 13-21

 

14.0 Processing and Recovery Methods 14-1

 

14.1 Summary 14-1

 

14.2 Plant C 14-4

 

14.3 Plant W 14-4

 

14.4 Zinc Concentrate Dewatering 14-5

 

14.5 Tailings Dewatering 14-5

 

14.6 Concentrate Handling 14-5

 

 

 

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14.7 Concentrate Sales and Processing 14-6

 

14.8 Energy, Water, and Process Materials Requirements 14-6

 

14.9 Manpower 14-6

 

15.0 Infrastructure 15-1

 

15.1 Infrastructure 15-1

 

16.0 Market Studies 16-1

 

16.1 Markets 16-1

 

16.2 Contracts 16-1

 

17.0 Environmental Studies, Permitting, and Plans, Negotiations, or Agreements with Local Individuals or Groups 17-1

 

17.1 Environmental Aspects 17-1

 

17.2 Mine Waste and Water Management 17-8

 

17.3 Project Permitting 17-12

 

17.4 Social or Community Requirements 17-15

 

17.5 Mine Closure Requirements 17-20

 

18.0 Capital and Operating Costs 18-1

 

18.1 Capital Costs 18-1

 

18.2 Operating Costs 18-1

 

19.0 Economic Analysis 19-1

 

19.1 Economic Criteria 19-1

 

19.2 Cash Flow 19-3

 

19.3 Sensitivity Analysis 19-6

 

20.0 Adjacent Properties 20-1

 

21.0 Other Relevant Data and Information 21-1

 

22.0 Interpretation and Conclusions 22-1

 

22.1 Geology and Mineral Resources 22-1

 

22.2 Mining and Mineral Reserves 22-1

 

22.3 Mineral Processing 22-2

 

22.4 Environment & Social 22-3

 

22.5 Costs and Economic Analysis 22-4

 

23.0 Recommendations 23-1

 

23.1 Geology and Mineral Resources 23-1

 

23.2 Mining and Mineral Reserves 23-1

 

23.3 Mineral Processing 23-2

 

23.4 Environment & Social 23-2

 

 

 

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23.5 Cost and Economic Analysis 23-3

 

24.0 References 24-1

 

25.0 Reliance on Information Provided by the Registrant 25-1

 

26.0 Date and Signature Page 26-1

 

 

 

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TABLEs

   

Table 1-1: Cash Flow Summary 1-22
     
Table 1-2: Summary of Mineral Resources as of December 31, 2020 1-25
     
Table 1-3: Summary of Mineral Reserves as of December 31, 2020 1-26
     
Table 1-4: Sustaining Capital Cost Estimate 1-30
     
Table 1-5: Operating Cost Estimate 1-31
     
Table 3-1: List of Mining Concessions, Mining Applications, and Right to Apply for Mining Concessions 3-4
     
Table 3-2: List of Exploration Licenses 3-6
     
Table 3-3: List of Surface Rights 3-10
     
Table 5-1: Summary of Exploration and Development History 5-2
     
Table 5-2: Summary of Open Pit Mine Production 5-7
     
Table 5-3: Summary of Underground Mine Production 5-8
     
Table 7-1: Summary of Ground Based Geophysical Surveys 7-11
     
Table 7-2: Summary of Regional Exploration Drilling 7-22
     
Table 7-3: Summary of the Open Pit, Underground, and Tailings Sample Drill Hole and Sampling Data as at April 30, 2020 7-23
     
Table 7-4: Summary of Extension Drilling Completed by Year 7-25
     
Table 7-5: Summary of Zinc Mineralization, Extremo Norte and Lumiadeira/Sucuri Deposits 7-35
     
Table 7-6: Summary of Zinc Mineralization, Aroeira Tailings Drill Holes 7-36
     
Table 7-7: Example of Zinc Mineralization, Calamine Drilling 7-37
     
Table 8-1: Summary of Analytical Procedures for the Vazante Laboratory 8-4
     
Table 8-2: Summary of QA/QC Protocols 8-5
     
Table 8-3: Summary of QA/QC Samples Processed from July 1, 2019 to April 15, 2020 8-6
     
Table 8-4: Summary of QA/QC Samples from the Calamine 2017, 2018, and 2019 Drilling Programs 8-8
     
Table 10-1: Pilot Study Aroeira Tailings Sample Composition 10-2
     
Table 10-2: Vazante Historical Performance 10-5
     
Table 11-1: Summary of Mineral Resources as of December 31, 2020 11-2
     
Table 11-2: Summary of Drill Hole and Channel Sample Databases, Vazante and Extremo Norte 11-4
     
Table 11-3: Summary Of Uncapped, Clustered Raw Sample Statistics, Willemite Mineralization 11-16
     
Table 11-4: Summary of Capped, Declustered Sample Statistics, Willemite Mineralization 11-23
     
Table 11-5: Summary of Capped, Composite Sample Statistics, Willemite Mineralization 11-24
     
Table 11-6: Summary of Variogram Parameters, Willemite Mineralization 11-30

 

 

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Table 11-7: Block Model Definition, Vazante and Extremo Norte Deposits 11-33
     
Table 11-8: List of Block Model Attributes, Vazante and Extremo Norte Deposits 11-34
     
Table 11-9: Search Parameters and Estimation Strategies, Primary Mineralized Wireframe, Vazante Deposit 11-35
     
Table 11-10: Comparison of Composite Sample Grades with Estimated Block Model Grades, Willemite 11-36
     
Table 11-11: Resource NSR Data- Willemite Mineralization 11-51
     
Table 11-12: Average NSR Factors For the Willemite Mineralization 11-53
     
Table 11-13: Mineral Resources for the Vazante and Extremo Norte Mineralization as of December 31, 2020 11-57
     
Table 11-14: Summary of Previous Mineral Resources as of December 31, 2019 11-57
     
Table 11-15: Summary of Drill Hole Database, Calamine Mineralization 11-59
     
Table 11-16: Summary of Uncapped, Clustered Raw Sample Statistics, Calamine Mineralization 11-68
     
Table 11-17: Summary of Capped, Declustered Sample Statistics, Calamine Mineralization 11-69
     
Table 11-18: Summary of Capped, Composite Sample Statistics, Calamine Mineralization 11-70
     
Table 11-19: Summary of Bulk Density Measurements, Supergene Mineralization 11-73
     
Table 11-20: Summary of Variogram Parameters, Supergene Mineralization 11-74
     
Table 11-21: Initial Block Model Definition, Supergene Mineralization 11-75
     
Table 11-22: List of Initial Block Model Attributes, Calamine Mineralization 11-75
     
Table 11-23: List Of Re-Blocked Block Model Attributes, Supergene Mineralization 11-76
     
Table 11-24: Search Parameters and Estimation Strategies, Supergene Mineralization 11-77
     
Table 11-25: Comparison of Composite Sample Grades with Estimated Block Model Grades, Supergene Mineralization 11-78
     
Table 11-26: Block Model NSR Data- Calamine Mineralization 11-84
     
Table 11-27: Average NSR Factors for the Supergene Mineralization 11-86
     
Table 11-28: Summary of the Whittle Input Parameters 11-87
     
Table 11-29: Mineral Resources For the Calamine Mineralization as of December 31, 2020 11-89
     
Table 11-30: Summary of Drill Hole Database, Tailings Mineralization 11-91
     
Table 11-31: Summary of Uncapped, Clustered Raw Sample Statistics, Aroeira Tailings 11-97
     
Table 11-32: Summary of Capped, Composite Statistics, Aroeira Tailings 11-99
     
Table 11-33: Summary of Variogram Parameters, Aroeira Tailings 11-101
     
Table 11-34: Initial Block Model Definition, Aroeira Tailings 11-102
     
Table 11-35: List of Initial Block Model Attributes, Aroeira Tailings 11-102
     
Table 11-36: List of Re-Blocked Block Model Attributes, Aroeira Tailings 11-103

 

 

 

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Table 11-37: Search Parameters and Estimation Strategies, Aroeira Tailings 11-104
     
Table 11-38: Comparison of Composite Sample Grades with Estimated Re-Blocked Model Grades, Aroeira Tailings 11-105
     
Table 11-39: Block Model NSR Data- Aroeira Tailings 11-111
     
Table 11-40: Average NSR Factors for the Aroeira Tailings 11-113
     
Table 11-41: Mineral Resources for the Aroeira Tailings as of December 31, 2020 11-114
     
Table 12-1: Summary of Mineral Reserves as of December 31, 2020 12-1
     
Table 12-2: Mine Dilution 12-2
     
Table 12-3: Mining Quality Control 2020 12-3
     
Table 12-4: Mining Extraction Factors 12-4
     
Table 12-5: Rock Mass Quality 12-5
     
Table 12-6: Modified Stability Number 12-5
     
Table 12-7: Rock Mass Classification 12-6
     
Table 12-8: NSR Data 12-11
     
Table 12-9: Average NSR Factors 12-12
     
Table 12-10: Reconciliation Data 12-13
     
Table 12-11: Recovered Compared to Reserve Model 12-13
     
Table 13-1: Stope Average Widths (2019 YE) 13-1
     
Table 13-2: Range of Mineralization Dips 13-3
     
Table 13-3: LOM Production 13-9
     
Table 13-4: Mine Ventilation Air Flow 13-18
     
Table 13-5: Mine Equipment 13-21
     
Table 13-6: Equipment Statistics 13-21
     
Table 13-7: Personnel 13-22
     
Table 17-1: Operating Licences 17-12
     
Table 17-2: Licences for Water Management and Water Use 17-13
     
Table 18-1: Sustaining Capital Cost Estimate 18-1
     
Table 18-2: Operating Cost Estimate 18-2
     
Table 19-1: After-Tax Cash Flow Summary 19-4
     
Table 19-2: Cash Flow Analysis 19-6
     
Table 19-3: After-Tax Sensitivity Analysis 19-7

 

 

 

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FIGURES

   

Figure 3-1: Location Map 3-2
     
Figure 3-2: Location of Mining Concessions and Mineralization 3-5
     
Figure 3-3: Location of Exploration Concessions 3-9
     
Figure 3-4: Location of Surface Rights Titles 3-12
     
Figure 5-1: Underground Mine Development 1982 to 2019, Vazante and Extremo Norte Mines 5-6
     
Figure 5-2: Summary of Open Pit and Underground Mine Production 5-9
     
Figure 6-1: Regional Geology 6-2
     
Figure 6-2: Geological Map of the Amazonian Shield 6-3
     
Figure 6-3: Regional Geological Map of the Brasilia Fold Belt 6-5
     
Figure 6-4: Local Geology of the Vazante Mine Area 6-6
     
Figure 6-5: Generalized Stratigraphic Column of the Vazante Area 6-7
     
Figure 6-6: Property Geology 6-9
     
Figure 6-7: Examples of Phyllites of the Serra Do Garrote Formation 6-10
     
Figure 6-8: Intraclast Breccias with Subangular Clasts in Dolomite Matrix, with Stromatactis Filled with Dolomite 6-11
     
Figure 6-9: Images of Gray, Massive Dolomite Containing Birds-Eyes (A), and Bird’s Eyes Structures (B) 6-11
     
Figure 6-10: View of a Metapelite Featuring Two Metamorphic Foliations Oriented Oblique to Each Other 6-12
     
Figure 6-11: View of Pink-Coloured Dolomite with Algal Mats and Primary Bedding (A) and Containing Meta-Marl Intercalations (B) 6-13
     
Figure 6-12: Example of Dolomite Breccia with Intense Veinlet Development 6-14
     
Figure 6-13: Typical Example of Alteration Style and Mineralogy 6-15
     
Figure 6-14: View of the Geology, Alteration, and Mineralization 6-17
     
Figure 6-15: Cross Section of the Lumiadeira Area, Vazante Mine 6-19
     
Figure 6-16: Cross Section of the Sucuri Area, Vazante Mine 6-20
     
Figure 6-17: Proposed Paragenetic History of the Extremo Norte Deposit 6-22
     
Figure 6-18: Proposed Genetic Model for the Extremo Norte Deposit 6-23
     
Figure 6-19: View of In-Situ Calamine Mineralization 6-24
     
Figure 6-20: Example of Calamine Mineralization in Drill Core 6-25
     
Figure 7-1: Location Plan, Rock Chip Samples 7-3
     
Figure 7-2: Location Plan, Panning Concentrate Samples 7-4

  

 

 

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Figure 7-3: Location Plan, Stream Sediment Samples 7-5
     
Figure 7-4: Location Plan, Soil Samples 7-6
     
Figure 7-5: Regional Magnetic Data for the Vazante Mine Area 7-8
     
Figure 7-6: Regional Gamma Spectroscopy Data for the Vazante Mine Area 7-9
     
Figure 7-7: Zinc Occurrences of the Vazante Mine Area 7-14
     
Figure 7-8: Hydrothermal Breccia and Zinc Sulphide Mineralization from the Sungem Target 7-15
     
Figure 7-9: Vein-Hosts Sphalerite in Veins Associated with Hydrothermal Dolomite and Quartz, Mata Preta Prospect 7-16
     
Figure 7-10: Location of the Mata Preta Prospect and Potential Mineralized Corridor 7-17
     
Figure 7-11: Three Dimensional Model of the Mata Preta Prospect Showing Multi Element Geochemical Anomalies 7-18
     
Figure 7-12: Compilation of Historical Results, Carrapato Trend 7-19
     
Figure 7-13: Exploration Potential of the Carrapato Trend 7-19
     
Figure 7-14: Location of Regional Exploration Drill Holes 7-21
     
Figure 7-15: Location of Drill Holes and Channel Samples, Vazante and Extremo Norte Deposits 7-24
     
Figure 7-16: View of Vazante Core Logging Facilities 7-27
     
Figure 7-17: View of the Vazante Operation Tailings Storage Facilities 7-28
     
Figure 7-18: View of the Tailings Sampling Drilling Equipment 7-28
     
Figure 7-19: Collar Locations for the Antiga and Aroeira Tailings Drill Holes 7-29
     
Figure 7-20: Representative Cross Section of the Extremo Norte Deposit 7-31
     
Figure 7-21: Representative Cross Section of the Vazante Deposit 7-32
     
Figure 7-22: Representative Cross Section of the Aroeira Tailings Sampling Program 7-33
     
Figure 7-23: Representative Cross Section of the Calamine Mineralization 7-34
     
Figure 8-1: Comparison of Bulk Density Measurements 8-2
     
Figure 8-2: Zinc Blank Sample Control Chart, July 1, 2019 to April 15, 2020 8-6
     
Figure 8-3: Zinc Standard Reference Material (BRMVZSTD007) Control Chart, July 1, 2019 to April 15, 2020 8-7
     
Figure 8-4: Zinc Pulp Duplicate Sample Control Chart, July 1, 2019 to April 15, 2020 8-7
     
Figure 8-5: Zinc Replicate Sample Control Chart, July 1, 2019 to April 15, 2020 8-8
     
Figure 10-1: Rougher Variability Test Work Results 10-3
     
Figure 11-1: Drill Hole and Channel Sample Locations, Vazante and Extremo Norte Deposits 11-5
     
Figure 11-2: Relative Value by Metal, Willemite Mineralization 11-7
     
Figure 11-3: View of the Mineralized Wireframe Outlines, Willemite Mineralization 11-8

   

 

 

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Figure 11-4: Sample Cross Section of the Mineralized Wireframes, Vazante Mine 11-9
     
Figure 11-5: Plan View of the Topographic Surfaces 11-11
     
Figure 11-6: Plan and Longitudinal Views of the Underground Development 11-12
     
Figure 11-7: Longitudinal View of the Mined Excavations, Vazante Mine 11-14
     
Figure 11-8: Longitudinal View of the Mined Excavations, Extremo Norte Mine 11-15
     
Figure 11-9: Raw Assay Histogram and Probability Plots for Zinc Within the Primary Mineralized Wireframe, Vazante Deposit 11-17
     
Figure 11-10: Raw Assay Histogram and Probability Plots for Zinc Within the Secondary Mineralized Wireframe, Vazante Deposit 11-18
     
Figure 11-11: Raw Assay Histogram and Probability Plots for Zinc Within the Tertiary Mineralized Wireframe, Vazante Deposit 11-19
     
Figure 11-12: Raw Assay Histogram and Probability Plots for Zinc Within the Primary Mineralized Wireframe, Extremo Norte Deposit 11-20
     
Figure 11-13: Raw Assay Histogram and Probability Plots for Zinc Within the Secondary Mineralized Wireframe, Extremo Norte Deposit 11-21
     
Figure 11-14: Raw Assay Histogram and Probability Plots for Zinc Within the Secondary Mineralized Wireframe, Extremo Norte Deposit 11-22
     
Figure 11-15: Relationship of Measured Bulk Density with Zinc, Lead, and Iron Grades, Vazante Deposit 11-25
     
Figure 11-16: Relationship of Measured Bulk Density with Zinc, Lead, and Iron Grades, Extremo Norte Deposit 11-26
     
Figure 11-17: Contoured Zinc Grades, Vazante Deposit 11-28
     
Figure 11-18: Example Variograms for Zinc Grades Contained Within the Primary Mineralized Wireframe Domain, Vazante Deposit 11-29
     
Figure 11-19: Example Variograms for Zinc Grades Contained Within the Primary Mineralized Wireframe Domain, Extremo Norte Deposit 11-30
     
Figure 11-20: Swath Plots for Zinc, Primary Mineralized Wireframes, Vazante Deposit 11-38
     
Figure 11-21: Swath Plots for Zinc, Primary Mineralized Wireframes, Extremo Norte Deposit 11-39
     
Figure 11-22: Quantile-Quantile Plots of the Zinc Grades, Vazante Deposit 11-40
     
Figure 11-23: Quantile-Quantile Plots of the Zinc Grades, Extremo Norte Deposit 11-41
     
Figure 11-24: Scatter Plots of the Zinc Grades, Vazante Deposit 11-43
     
Figure 11-25: Scatter Plots of the Zinc Grades, Extremo Norte Deposit 11-44
     
Figure 11-26: Normal Scores Histogram Plots of the Zinc Grades, Vazante Deposit 11-46
     
Figure 11-27: Normal Scores Histogram Plots of the Zinc Grades, Extremo Norte Deposit 11-47
     
Figure 11-28: View of the Final Mineral Resource Classification, Primary Mineralized Wireframe, Vazante Deposit 11-49

  

 

 

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Figure 11-29: View of the Final Mineral Resource Classification, Primary Mineralized Wireframe, Extremo Norte Deposit 11-50
     
Figure 11-30: Zinc Grade-Recovery Curve for the Willemite Mineralization 11-52
     
Figure 11-31: Lead Grade-Recovery Curve for the Willemite Mineralization 11-53
     
Figure 11-32: View of the Mineral Resource Reporting Panels, Vazante Deposit 11-55
     
Figure 11-33: View of the Mineral Resource Reporting Panels, Extremo Norte Deposit 11-56
     
Figure 11-34: Drill Hole Locations, Calamine Mineralization 11-61
     
Figure 11-35: Inclined View of the Lithology Model (Overburden Removed), Calamine Mineralization 11-62
     
Figure 11-36: Sample Cross Section of the Lithology and Weathering Models, Calamine Mineralization 11-63
     
Figure 11-37: View of the Mineralized Wireframe Outlines, Calamine Mineralization 11-65
     
Figure 11-38: Relative Value by Metal, Calamine Mineralization 11-66
     
Figure 11-39: Plan View of the Topographic Surface, Supergene Mineralization 11-67
     
Figure 11-40: Raw Assay Histogram and Probability Plots for Zinc Within the Calamine Mineralized Wireframes 11-69
     
Figure 11-41: Histogram of Sample Lengths Within the Calamine Mineralized Wireframes 11-70
     
Figure 11-42: Examples of Mineralization Styles and Material Types, Supergene Mineralization 11-72
     
Figure 11-43: Omni Directional Variogram, Zinc, Supergene Mineralization 11-74
     
Figure 11-44: Swath Plot for Zinc, Calamine 11-79
     
Figure 11-45: Quantile-Quantile Plot of the Zinc Grades, Supergene 11-80
     
Figure 11-46: Scatter Plot of the Zinc Grades, Supergene 11-81
     
Figure 11-47: Normal Scores Plot of the Zinc Grades, Supergene 11-82
     
Figure 11-48: View of the Final Classified Mineral Resources, Supergene 11-83
     
Figure 11-49: Zinc Grade-Recovery Curve for the Supergene Mineralization 11-85
     
Figure 11-50: Lead Grade-Recovery Curve for the Supergene Mineralization 11-86
     
Figure 11-51: Plan View of the Open Pit Surface, Supergene Mineral Resources 11-88
     
Figure 11-52: Drill Hole Location Map, Tailings Sampling Programs 11-92
     
Figure 11-53: Inclined View of the Planned vs Completed Drill Holes, Aroeira Tailings 11-93
     
Figure 11-54: Plan View of the Drill Hole Locations and Mineralized Wireframe, Aroeira Tailings 11-94
     
Figure 11-55: View of the Aroeira Tailings Storage Area as of December 8, 2020 11-96
     
Figure 11-56: Frequency Histogram of the Zinc Uncapped Raw Sample Statistics, Aroeira Tailings 11-97

 

 

 

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Figure 11-57: Frequency Histogram of the Lead Uncapped Raw Sample Statistics, Aroeira Tailings 11-98
     
Figure 11-58: Frequency Histogram of the Silver Uncapped Raw Sample Statistics, Aroeira Tailings 11-98
     
Figure 11-59: Histogram of Sample Lengths, Aroeira Tailings Samples 11-99
     
Figure 11-60: Distribution of Dry Bulk Density Measurements, Aroeira Tailings 11-100
     
Figure 11-61: Example Variograms for Zinc Grades Contained Within the Aroeira Tailings Mineralized Wireframe Domain 11-101
     
Figure 11-62: Swath Plot for Zinc, Aroeira Tailings 11-106
     
Figure 11-63: Quantile-Quantile Plot of the Zinc Grades, Aroeira Tailings 11-107
     
Figure 11-64: Scatter Plot of the Zinc Grades, Aroeira Tailings 11-108
     
Figure 11-65: Normal Scores Plot of the Zinc Grades, Aroeira Tailings 11-109
     
Figure 11-66: Excavation of the Aroeira Tailings 11-110
     
Figure 11-67: Zinc Grade-Recovery Curve for the Aroeira Tailings 11-112
     
Figure 11-68: Lead Grade-Recovery Curve for the Aroeira Tailings 11-113
     
Figure 12-1: Empirical Support Chart 12-6
     
Figure 12-2: ELOS Graph for Vazante Mine 12-8
     
Figure 12-3: Stope Stability Graph 12-9
     
Figure 13-1: Mine Longitudinal Section Showing Resource Thickness Contours 13-2
     
Figure 13-2: VRM and SLOS Longhole Stope Layouts 13-5
     
Figure 13-3: VRM Longhole Stope Sequence Schematic 13-6
     
Figure 13-4: Cut and Fill Stoping Schematic 13-8
     
Figure 13-5: Mine Production Profile for LOM 13-10
     
Figure 13-6: Mine Development Profile for LOM 13-10
     
Figure 13-7: Mine Deepening Project Longitudinal Section 13-12
     
Figure 13-8: Mine Dewatering Rate 13-13
     
Figure 13-9: Historical Rain and Dewatering Rates 13-13
     
Figure 13-10: Cumulative Development versus Pumping Rate 13-14
     
Figure 13-11: Mine Longitudinal Section Showing Extent of Mine Workings and Water Table Levels 13-15
     
Figure 13-12: Registered Sinkholes (January 2006 to July 2020) 13-16
     
Figure 13-13: Registered Sinkholes (2001 to 2020) 13-17
     
Figure 13-14: Vazante LOM Airflow 13-19
     
Figure 13-15: Extremo Norte LOM Airflow 13-20

 

 

 

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Figure 13-16: Mine Ventilation Schematic Diagram 13-20
     
Figure 14-1: Process Block Flow Diagram 14-2
     
Figure 14-2: Simplified Process Flow Sheet 14-3
     
Figure 15-1: Vazante Mine Surface Infrastructure 15-2
     
Figure 15-2: Site Plan 15-3
     
Figure 15-3: General Site Layout, Process Plant Area 15-4
     
Figure 15-4: General Site Layout, Administration Area 15-5
     
Figure 15-5: Aroeira Tailings Storage Facility Plan View and Dam Typical Cross-Section 15-9
     
Figure 15-6: Pilha Garrote Dry Stack Tailings Storage Facility Plan View and Typical Cross Section 15-10
     
Figure 19-1: After-Tax NPV Sensitivity Graph 19-8

  

 

 

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1.0 Executive Summary

 

1.1 Summary

 

SLR Consulting Ltd. (SLR) was retained by Nexa Resources S.A. (Nexa) to prepare an independent Technical Report Summary on the Vazante Polymetallic Operations (the Vazante Operation), located in the state of Minas Gerais, Brazil. The purpose of this Technical Report Summary is to support the disclosure of Mineral Resource and Mineral Reserve estimates for the Vazante Operation as of December 31, 2020. This Technical Report Summary conforms to United States Securities and Exchange Commission’s (SEC) Modernized Property Disclosure Requirements for Mining Registrants as described in Subpart 229.1300 of Regulation S-K, Disclosure by Registrants Engaged in Mining Operations (S-K 1300) and Item 601 (b)(96) Technical Report Summary. SLR visited the property from November 19 to 23, 2018.

 

Nexa is a publicly traded company on the Toronto Stock Exchange (TSX) and the New York Stock Exchange (NYSE). Nexa is a reporting issuer in all provinces and territories of Canada and is under the jurisdiction of the Ontario Securities Commission.

 

Nexa is a large-scale, low-cost, integrated zinc producer with over 60 years of experience developing and operating mining and smelting assets in Latin America. Nexa has a diversified portfolio of polymetallic mines (zinc, lead, copper, silver, and gold) and also greenfield projects at various stages of development in Brazil and Peru. In Brazil, Nexa owns and operates two underground mines, Vazante and Morro Agudo (Zn and Pb). It also operates two zinc smelters in Brazil (Três Marias and Juiz de Fora). In Peru, Nexa operates the El Porvenir (Zn, Pb, Cu, and Ag), Cerro Lindo (Zn, Cu, Pb, and Ag), and Atacocha (Zn, Cu, Pb, Au, and Ag) mines, as well as the Cajamarquilla zinc smelter near Lima. Nexa’s development projects in Peru include Magistral, Shalipayco, Florida Canyon (JV with Solitario), Hilarión, and Pukaqaqa. In Brazil, Nexa is developing the Aripuanã Zinc Project (Zn, Pb, Cu, Au, and Ag), which is currently under construction.

 

Nexa’s wholly owned Vazante Operation is located approximately 8.5 km from the municipality of Vazante, in Minas Gerais State, Brazil. The Vazante Operation comprises the Vazante underground zinc-lead–silver mine (the Vazante Mine) and the Extremo Norte underground zinc–lead–silver mine (the Extremo Norte Mine), both featuring zinc silicate ore and lead/silver associated with sulphides. Mechanized open pit mining commenced in 1969, and underground mining at the Vazante Mine commenced in 1983. Access is through two portals for the Vazante Mine and one portal for the Extremo Norte Mine. As development progresses at the Extremo Norte Mine, a connecting drift will be established from the Vazante Mine to the Extremo Norte Mine. The Vazante Operation ore is treated at a concentrate plant that has a processing capacity of approximately 4,400 tonnes per day (tpd) or 1.6 million tonnes per annum (Mtpa). The Vazante Operation produces separate zinc silicate and lead sulphide concentrates. The zinc concentrate is processed at Nexa’s Três Marias smelter in Brazil approximately 250 km from the Vazante Operation, while the lead concentrate is sold on the open market. In 2020 the Vazante Operation produced 147,990 tonnes of zinc contained in zinc concentrate and 1,333 tonnes of lead contained in lead concentrate.

 

 

 

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1.1.1 Conclusions

 

SLR offers the following conclusions by area.

 

1.1.1.1 Geology and Mineral Resources

 

· Mineral Resources have been estimated for three styles of mineralization – hypogene (willemite) mineralized zones, where mining currently takes place; supergene (calamine) mineralization, located near surface; and tailings contained within the Aroeira Tailings Storage Facility (TSF).

 

· As prepared by Nexa and adopted by SLR, the Vazante Measured and Indicated Mineral Resources, effective as of December 31, 2020 and exclusive of Mineral Reserves, comprise 6.3 million tonnes (Mt) at grades of 6.88% Zn, 0.16% Pb, and 7.1 g/t Ag, containing 432.3 kt Zn, 10.2 kt Pb, and 1.44 million ounces (Moz) Ag. In addition, Inferred Mineral Resources comprise 13.8 Mt, at grades of 6.86% Zn, 0.18% Pb, and 9.5 g/t Ag, containing 950.2 kt Zn, 25.5 kt Pb, and 4.2 Moz Ag.

 

· Mineral Resources have been classified in accordance with the definitions for Mineral Resources in S-K 1300, which are consistent with Canadian Institute of Mining, Metallurgy and Petroleum (CIM) Definition Standards for Mineral Resources and Mineral Reserves dated May 10, 2014 (CIM (2014) definitions).

 

· The geological data and procedures are adequate for the estimation of Mineral Resources and comply with industry standards.

 

· The “Reasonable Prospects for Economic Extraction” requirement of S-K 1300 resource definitions is satisfied by:

 

o Reporting panels that have been created so as to achieve the required spatial continuity, cut-off grade, and minimum width criteria for the underground hypogene mineralization.

 

o Open pit shells for the supergene mineralization.

 

o The use of the original topographical surface as a constraint for the tailings mineralization.

 

· Location data for the supergene and tailings drill holes is stored in a surface UTM coordinate system, while the hypogene drill data has been converted to an underground mine grid coordinate system.

 

1.1.1.2 Mining and Mineral Reserves

 

· The Vazante Operation deposits support an average production rate of 1.5 Mtpa over the LOM, producing from 69,000 t Zn per year to 135,000 t Zn per year contained in zinc concentrate depending on head grade.

 

· Deposit geometry and geomechanical properties are amenable to bulk longhole mining methods. The sublevel stoping (SLS) methods used at the Vazante Mine consist of a combination of downholes or vertical retreat mining (VRM) where stopes are backfilled with run of mine rock and up-holes or sublevel longhole open stopes (SLOS) which are not backfilled.

 

· As prepared by Nexa and adopted by SLR, the Vazante Proven and Probable Mineral Reserves, effective as of December 31, 2020, comprise 16.7 Mt at grades of 8.61% Zn, 0.23% Pb, and 13.7 g/t Ag, containing 1.44 Mt Zn, 38,000 t Pb, and 7.37 Moz Ag.

 

· Mineral Reserves have been classified in accordance with the definitions for Mineral Reserves in S-K 1300, which are consistent with CIM (2014) definitions.

 

 

 

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· Dilution and extraction estimates include:

 

o Dilution – planned dilution for SLS assumes an estimate of the equivalent length of slough (ELOS, m) depending on the dip of the stope, ranging from zero metres to 0.75 m in the hanging wall and zero metres to 0.25 m in the footwall.

 

o Pillars are also used to control stope dilution. These include the use of sill pillars between mining sublevels, island pillars located at the centre of stopes, and rib pillars positioned at the extremities of the stopes to reduce the potential for excess sloughing from the hanging wall contact and control dilution from adjacent filled stopes.

 

o Extraction – initial selection of resources by stope optimization and design, plus additional factors of 83% to 98% by mining method, and 35% to 60% for pillar recovery.

 

· The Vazante Operation requires extreme dewatering to operate, with pumping capacity increasing over time as total mine workings increase in size. The pumping rates in 2020 averaged approximately 12,500 m³/h, which while in excess of recent modelling, is well within the installed pumping capacity of the Vazante Operation (20,000 m3/h).

 

· The second of a two-phase Mine Deepening Project (MDP) is underway with the water pumping capacity to increase at the bottom of the mine from 10,000 m3/h to 15,000 m³/h to be completed in 2022.

 

1.1.1.3 Mineral Processing

 

· Recovery of zinc from silicate minerals is not common, however, processing via flotation works in a manner similar to recovery of zinc from sulphides. Recovery of zinc metal from zinc silicate concentrates, however, is quite different compared to recovery from sulphides, requiring hydrometallurgical processing at a dedicated facility such as Nexa’s Três Marias smelter.

 

· Zinc recovery has been shown to be related to head grade. The head grade of the processing plant feed is forecast to decrease over the remainder of the LOM, therefore, recovery and zinc concentrate production are also forecast to decrease over the remainder of the LOM, even though the ore processing rate is forecast to continue at current rates until the final year in the LOM.

 

· In the SLR Qualified Person’s (QP) opinion, the use of past operating performance to derive a head grade versus recovery relationship for zinc (and lead) is reasonable and adequate to predict future plant performance for future head grades and ore types similar to those processed in the past few years.

 

· Plant feed is supplemented from time to time with small amounts of willemite tailings recovered from the Aroeira TSF and blended with the fresh ore, however, Nexa is considering increasing the tailings reprocessing rate to up to 10% of plant feed. Pilot plant test work using column flotation has been conducted to assess the possibility of processing tailings separately to improve zinc recovery and results have been positive. Variability test work on samples of tailings from the Aroeira TSF is underway to help evaluate the variability of metallurgical response of the tailings.

 

· Nexa has identified calamine resources in the Extremo Norte deposit area and along the strike length, as well as in historical tailings (the Aroeira TSF), and potential calamine resources in other historical tailings deposits. Nexa is conducting test work on calamine mineralization from the Extremo Norte area to try to improve on historical calamine processing performance, which was characterized as challenging with zinc recovery of only 50%.

 

 

 

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o Bench-scale open circuit rougher-scavenger test work using conventional mechanical cells achieved approximately 23% Zn in concentrate at a recovery of up to 70%. An open circuit cleaner test produced a concentrate grading 39% Zn (the target zinc grade for concentrate being processed at Nexa’s Três Marias smelter) and a recovery of 63%.

 

o Pilot plant test work at the Vazante Operation using conventional mechanical cells demonstrated that overall zinc recovery of up to 50% at concentrate grades over 37% was possible. The majority of zinc losses (approximately 60%) were to the fines fraction (< 38 µm) removed prior to flotation and occurring mainly as hemimorphite. Nexa noted that the use of column cells rather than mechanical cells could provide some improvement in yield due to the large proportion of fines in the feed, and that further assessment of collectors and fatty acids was necessary to improve the recovery of hemimorphite.

 

1.1.1.4 Environment & Social

 

· No environmental issues were identified from the documentation available for review that could materially impact the ability to extract the Mineral Resources and Mineral Reserves. The Vazante Operation has all the environmental operational licences required for operation according to Brazilian legislation. The approved licences address the authority’s requirements for mining extraction and operation activities. The Vazante Operation has not applied for new permits and SLR is not aware of any new projects or modification to the existing operations triggering permitting processes. Four active Operation Licences are in the process of renewal through Council of Environmental Policy (COPAM) No. 104/1988/059/2016.

 

· The environmental programs defined in the Environmental Control Plans, Plano de Controle Ambiental (PCAs) are an integral part of the Environmental Management System for adoption of measures aimed at the prevention, mitigation, and control of potential environmental impacts resulting from mining activities. Results of the environmental programs including monitoring of water quality, air quality and noise are documented in annual reports submitted to the authorities (SUPRAM-NOR). The SLR QP is not aware of non-compliance issues raised by the authorities. In the SLR QP’s opinion, the environmental management programs for Vazante are adequate to address potential issues related to environmental compliance.

 

· Nexa utilizes an Integrated Dam Management System (referred to as SIGBar) which provides guidelines for document management, monitoring, evaluation, risk analysis, compliance with standards and legislation, training of personnel, operation of structures and other provisions.

 

· Tailings are currently disposed of as filtered tailings at the Pilha Garrote dry stack tailings storage facility (DSTSF). The Aroeira TSF, the former primary location for tailings disposal until August 2019, will remain operational as a water storage facility.

 

· Regular dam safety inspections have visually confirmed that the tailings beach of the Aroeira TSF between the dam and the tailings pond is greater than 40 m.

 

· Dam monitoring consists of instrument measurements and field inspections. Dam monitoring data is reviewed by an external consultant (Geoconsultoria) on a monthly basis. Fortnightly inspections are completed by Nexa personnel and every six months by Geoconsultoria. The latest review by Geoconsultoria that was reviewed by SLR was dated 30 August 2019 (Relatório Técnico CM18-RT57 Rev.0). Geoconsultoria’s report states the dam safety condition is “Satisfactory” without the presence of erosions, cracks, or other features indicative of instability.

 

· A Mine Closure Plan has been developed for all the Vazante Operation components within the context of Brazilian legislation and consideration to the VMH guideline for decommissioning (Guideline PG-VM-HSMQ-040 Revision 2.2). The most recent Mine Closure Plan and cost estimate were completed in January 2018.

 

 

 

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· A social baseline description, assessment of socio-economic impacts, and identification of socio-economic environment programs have been completed as part of the environmental impact assessments carried out to mitigate negative impacts and maximize positive benefits of the Vazante Operations. These components are generally consistent with social impact assessment practices. Nexa has developed and utilizes a number of social management programs and tools to help the it work with the nearby communities (risk analysis matrices, stakeholder tracking, social characterization plan and local development plan). In the SLR QP’s opinion the grievance mechanism in place and the social management programs and tools for the Vazante Operations, are adequate to address potential issues related to local communities.

 

· Nexa hires from the local workforce when possible, both for skilled and unskilled workers. Outreach to the local community is conducted through social and employment programs.

 

· No social issues were identified from the documentation available for review. The review of social aspects indicates that, at present, Nexa’s operations at the Vazante Operation are a positive contribution to sustainability and community wellbeing. Nexa has established and continues to implement its various corporate policies, procedures, and practices in a manner consistent with relevant International Finance Corporation (IFC) Performance Standards (PSs). Nexa has, and continues to make, a positive contribution to the communities most affected by the site operations and has done a thorough job in documenting potential effects on stakeholders and protecting the rights, health, and safety of its employees.

 

1.1.1.5 Costs and Economic Analysis

 

· The LOM operating cost forecast reflects the existing operating status of the Vazante Operation. SLR has reviewed recent operating costs and is of the opinion that the forecast is appropriate for the Vazante Operation.  Nexa also needs to continue assessing operating efficiencies and approaches in efforts to improve operating costs in the different cost centres.

 

· The economics of the Vazante Operation are robust over the LOM, confirming that the Mineral Reserves are economically viable.  The economic analysis indicates an after-tax net present value (NPV), at a 9% base discount rate, of $652 million.

 

1.1.2 Recommendations

 

SLR offers the following recommendations by area.

 

1.1.2.1 Geology and Mineral Resources

 

1. The coordinates for all supergene related drill holes be converted into the local mine grid coordinates so that the results from all Mineral Resource estimation activities can then be integrated with any underground mining activities that have been or are planned to be carried out in this area.

 

2. The drill hole dips for the drill holes examined be confirmed by direct visual inspection of the departing drill hole orientation at the drilling face.

 

3. The drill hole data relating to the tailings mineralization be converted into the mine grid coordinate system to more easily integrate the information for the underground mine.

 

 

 

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1.1.2.2 Mining and Mineral Reserves

 

1. In SLR’s opinion high mine dilution at the Vazante Operation is caused in part by the current cable bolting procedure, whereby bolts are installed from the undercut level and fanned into the hanging wall of the stope. The cable bolt coverage of the stope should be improved by drilling the cable bolt holes from a hanging wall access, where the cost can be justified. Additionally, SLR also recommends assessing the production drilling design to reduce the potential for dilution.

 

2. SLR observed secondary breaking on surface during the 2018 site visit. The stope drill patterns should be reviewed with the intent of reducing the level of stope dilution through adjustment of the drill pattern. This may require drilling an additional hole on the hanging wall contact, between the current burden spacing. A reduced explosive charge per hole, using a lower density explosive, would aid to effectively trim the hanging wall contact thereby providing a much cleaner break. The reduced blast vibration impact (a lower peak particle velocity (ppv)) would lead to a lower degree of overbreak on the hanging wall and less dilution.

 

3. Dilution will be an issue in the narrow cut and fill stopes, which are not yet reflected in Mineral Reserves, as the four metre minimum mining width will impact upon every lift taken. A stope width review should be carried out for the planned cut and fill stopes to determine whether the current equipment fleet matches the orebody dimensions.

 

4. Narrow vein equipment should be assessed as soon as possible to have it readily available at the time narrower areas are encountered in the lower levels of the mine.

 

5. A trial test stope using a smaller drill unit in the upper section of the mine should be completed to assess the efficacy and optimize the drilling layouts, as a prerequisite to eventual application of the method on a larger scale in the lower levels of the mine, when a larger portion of the mine production comes from this area.

 

6. The use of a “shanty back” configuration on the hanging wall side of the drift should be evaluated to reduce dilution.

 

7. Given the extreme dewatering that is required to permit ongoing mining, hydrologic monitoring is considered a critical element of operations. Continued calibration of flows is recommended to predict, plan, and install required pumping capacities for the Vazante Operation.

 

8. The water table levels should be monitored as planned to help foresee any potential issues and assess mitigation measures that may be required.

 

9. The use of cemented rock fill (CRF) is recommended to enable mining of certain pillars where this is economical. A trade-off analysis would be required in each case.

 

10. The reconciliation results and the stope performance analysis should be used to evaluate stope designs to determine where improvements in mine planning would be most advantageous.

 

1.1.2.3 Mineral Processing

 

1. Continue the variability test work and process development on samples of Aroeira willemite tailings to assess the variability of metallurgical response and provide an estimate of overall recovery from the willemite portion of the tails that can be used in economic studies of the installation of a dedicated tailings processing circuit.

 

2. Calamine processing test work: continue process development test work to improve recovery, including the evaluation of collectors for improved recovery of hemimorphite, and consider options that may help to improve recovery from calamine mineralization such as:

 

o Separate processing of calamine and willemite mineralization.

 

 

 

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o A coarser primary grind for calamine mineralization and evaluation of the effect of a coarser primary grind on the proportion of fines in the flotation feed and zinc (and zinc mineral) deportment to fines.

 

o Separate processing of the fines fraction to recover hemimorphite in a purpose-built fines processing circuit, which could also be used for processing historical calamine tailings.

 

3. Consider developing a combined strategy for processing historical tailings and calamine ore, since the two feeds, or portions of the feeds (e.g., calamine fines) may require similar equipment for processing; this strategy could then help with test work planning, production, and financial planning.

 

1.1.2.4 Environment & Social

 

1. Although it is not a requirement in the Operation Licences, SLR recommends considering the implementation of a monitoring program for flora and fauna for the Vazante Operation.

 

2. The Golder closure report (No. RT-006_169-525-2593_03-J 75, dated January 2018) recommends that a more detailed assessment be made of the impact of ore processing on the potential for release of sulphates from the tailings at the Pilha Garrote DSTSF.

 

3. The placement and compaction of the filtered and cyclone tailings during the wet season should be considered.

 

4. Dust generation from the Pilha Garrote DSTSF during the dry season must be considered.

 

5. The water balance for the Aroeira TSF must be reviewed through additional water balance modelling to determine the impact of use as a water management facility, increased mine dewatering and surface runoff from the Pilha Garrote DSTSF. Different climate scenarios should be simulated to account for years with annual precipitation below and above the statistical average (i.e. dry and wet years). The water balance modelling should be used to investigate changes in water availability for ore processing and changes in effluent discharge rates to the Santa Catarina River.

 

1.1.2.5 Cost and Economic Analysis

 

1. Continuously monitor costs and exchange rates and lock in costs as soon as possible to eliminate economic uncertainty.

 

2. Continue efforts towards improving efficiencies and approaches to mining and development operations as opportunities arise in these areas.

 

1.2 Economic Analysis

 

The economic analysis contained in this Technical Report Summary is based on the Mineral Reserves, economic assumptions provided by Nexa for the Vazante Operation, and the capital and operating costs as presented in Section 18 of this Technical Report Summary.

 

1.2.1 Economic Criteria

 

1.2.1.1 Revenue

 

· Revenue is estimated based on the following LOM average metal prices:

 

o Zinc price: US$2,491/t Zn

 

o Lead price: US$1,960/t Pb

 

o Silver price: US$17.01/oz Ag

 

 

 

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· Net Revenue includes the benefit of zinc smelting at cost (rather than at commercial third-party terms), due to integration with Nexa’s Três Marias refinery.

 

· Logistics, Treatment and Refining charges:

 

o LOM average Transportation/Logistics charges:

 

§ Zinc concentrate to Três Marias refinery: US$16.7/t concentrate

 

§ Lead concentrate to Asia: US$278.7/t concentrate

 

o Treatment Charges (TC):

 

§ LOM average TC for lead concentrate: US$200.4/t concentrate

 

§ LOM average refined zinc conversion costs at Três Marias: US$477/t

 

o Refining Charges:

 

§ Silver in lead concentrate: US$1.00/oz Ag

 

· LOM Net Revenue after Treatment and Refining charges is US$2,627 million.

 

1.2.1.2 Taxation and Royalties

 

· Corporate income tax rate in Brazil is 34%.

 

· CFEM royalty rate: 2%.

 

· SLR has relied on a Nexa taxation model for calculation of income taxes applicable to the cash flow.

 

1.2.2 Cash Flow

 

SLR reviewed the Vazante Operation LOM after-tax cash flow model to confirm the economics of the LOM plan. The model does not account for the following components:

 

· Financing costs

 

· Insurance

 

· Overhead cost for a corporate office

 

 

 

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A cash flow summary is presented in Table 1-1.

 

Table 1-1:                Cash Flow Summary 

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Parameter   Units   Undiscounted     Discounted at 9%  
Mill Feed, Total   Mt     16.7          
LOM   years     11          
Revenues   US$M     2,639       1,782  
Royalties   US$M     12.1       8  
Net Revenues   US$M     2,627       1,775  
Operating Costs                    
Mining   US$M     448       296  
Processing and Tailings   US$M     223       144  
G&A   US$M     85       54  
Total Operating Cost   US$M     755       495  
Sales Costs   US$M     71       47  
Other operating results   US$M     59       29  
EBITDA   US$M     1,742       1,204  
Capital Costs                    
Capital Costs (net of taxes)   US$M     83       63  
Sustaining Capital (net of taxes)   US$M     146       111  
Closure & Other   US$M     38       14  
Working Capital   US$M     8       0  
Total Capital Costs   US$M     275       189  
                     
Pre-tax Cash Flow   US$M     1,467       1,017  
Income Tax   US$M     514       365  
After-tax Cash Flow   US$M     954       652  
                     
Pre-tax NPV                    
NPV 8%   US$M             1,055  
NPV 9%   US$M             1,017  
NPV 10%   US$M             981  
                     
After-tax NPV                    
NPV 8%   US$M             677  
NPV 9%   US$M             652  
NPV 10%   US$M             628  

 

Note:

 

1. Numbers may not add due to rounding.

 

1.2.3 Sensitivity Analysis

 

Key economic risks were examined by running cash flow sensitivities on after-tax NPV at a 9% discount rate. The following items were examined:

 

· Metal prices

 

· Head grade

 

· Metallurgical recovery

 

· Operating costs, and

 

· Capital costs

 

The after-tax NPV is most sensitive to head grade, then to metal prices, followed by recovery, operating costs, and capital costs.

 

 

 

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1.3 Technical Summary

 

1.3.1 Property Description

 

Title to the Vazante Operation is held by Nexa Recursos Minerais S.A. (Nexa Brazil) and Mineração Soledade Ltda, a subsidiary of Nexa Brazil. Nexa Brazil holds two Mining Concessions and one Group of Mine Concessions, with the Group of Mine Concessions comprising six Mining Concessions. Surrounding the Mineral Resource/Mineral Reserve area, Nexa Brazil also holds 62 Exploration Licenses, three Rights to Apply for Mining Concession, two Mining Concessions, and one Mining Concession Application in addition to the core tenements.

 

1.3.2 Accessibility, Climate, Local Resources, Infrastructure, and Physiography

 

The Vazante Operation is located in the western portion of the state of Minas Gerais, Brazil at a latitude of approximately 17 57’ 33” S and a longitude of approximately 46° 49’ 42” W, within Zone 23S of the Universal Transverse Mercator coordinate system (Cόrrego Alegre Datum) at approximately 306,000 mE and 8,016,000 mN. The Vazante Operation is located approximately 8.5 km east of the town of Vazante, 253 km southeast of Brasilia, and 370 km northwest of Belo Horizonte.

 

The region is classified as warm, sub-humid with four to five dry months annually. Average temperatures vary between 13°C and 27°C in the winter and between 18°C and 30°C in the summer. The historical average annual rainfall is 1,441.5 mm, with more than 80% occurring during the rainy season, which runs from October to March. The predominant wind directions are northeast to southwest. The topography in the Vazante Operation area is characterized by gently rolling hillsides with incised streams and rivers. The elevations of the Vazante Operation area ranges from approximately 690 metres above mean sea level (masl) to 970 masl.

 

The main economic activities of the region include cattle raising, farming, and mining. Most of the mine employees reside in Vazante, which has a population of approximately 20,600, and commute to the mine site daily. Goods and services in support of mining operations are generally sourced from Belo Horizonte. The region is well serviced with electricity supplied from the national grid as well as modern telecommunications. Basic medical services are available in the town of Vazante, with higher levels of medical services available in Paracatu, Brasilia, or Belo Horizonte.

 

1.3.3 History

 

Mineralization in the Vazante Operation area was initially discovered by Angelo Solis in 1933 who acquired the first mineral titles to the area. The mineral rights to the Vazante Mine portion of the Vazante Operation land holdings were first acquired by Companhia Mineira de Metais (CMM) in 1956. CMM later became Votorantim Resources in 2005 and more recently Nexa Resources S.A. in 2014. The original land titles for the Vazante Operation were added and expanded over the years by means of direct land acquisition (claim staking) and various option agreements and purchases. The Extremo Norte Mine portion of the current Vazante Operation land holdings was acquired by purchase in 2007.

 

 

 

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1.3.4 Geological Setting, Mineralization, and Deposit

 

The geology of the Vazante Operation area consists of a sequence of pelitic carbonate rocks belonging to the Serra de Garrote and Serra do Poço Verde formations of the Vazante Group. The currently known mineralization has been traced along a strike length of approximately 10.5 km, extending from the southern end of the Vazante Mine to the northern limits of the Extremo Norte Mine.

 

The zinc-lead-silver mineralization at the Vazante Operation is hosted by the Vazante Shear Zone which has been traced by drilling and sampling along a strike length of approximately 12 km. The Vazante Shear Zone has a general strike of azimuth 50° and dips approximately 60° to the northwest at surface. The hanging wall lithologies of the Vazante Shear Zone are comprised of dolostone and sericitic phyllite, slates and marl units of the Serra do Poço Verde Formation while the footwall lithologies to the Vazante Shear Zone are dominated by dark grey dolostones of the Upper Morro do Pinheiro Member. Drilling information indicates that the dip of the zinc mineralized zone gradually decreases with depth in the southern portions of the structure.

 

The zinc mineralization at the Vazante and Extremo Norte mines is composed largely of hypogene zones that are composed mainly of willemite (Zn2SiO4) veins, veinlets, and stockworks that are hosted by sphalerite-rich carbonate. The mineralization typically contains willemite (50% to 70%), dolomite (10% to 30%), siderite (10% to 20%), quartz (10% to 15%), hematite (5% to 10%), zinc-rich chlorite (5% to 10%), barite (<5%), franklinite (<5%), and zincite (<5%), with subordinate concentrations of magnetite and apatite (Monteiro et. al., 2006). Lead and silver are also recovered from the hypogene mineralization is produced from the Vazante Operation. While no detailed studies regarding the specific lead and silver bearing minerals have been carried out on samples of the hypogene mineralization, several detailed mineralogical studies have been conducted using concentrate samples. SLR notes that the majority of the lead mineralization in the concentrates has been found to be related to galena (PbS), with lesser amounts of lead being contained in cerussite (Pb(CO3)). Mineralogical studies have indicated that the silver values are contained in the minerals acanthite (Ag2S) and jalpaite (Ag2CuS2).

 

Supergene zones of zinc-rich mineralization have been developed in the near-surface portions of the hypogene mineralized zones. These supergene zones are referred to as the calamine zones at the Vazante Operation. The calamine mineralization is composed principally of smithsonite (ZnCO3) that includes subordinate amounts of hemimorphite (Zn4(Si2O7)(OH)2.H2O) and quartz. The calamine mineralized zones were derived from weathering of the primary willemite mineralization.

 

1.3.5 Exploration

 

Zinc was first discovered at the Vazante Operation in 1951 when areas of gossan and calamine mineralization were discovered in surface outcrops. Since 1951, exploration has largely consisted of geological mapping and geophysical surveying, with minor amounts of geochemical sampling programs being carried out to locate outcropping mineralized zones. In the Vazante Operation area, exploration programs (including drilling) have strategically been carried out in support of extensions of mining operations, including the possibility of deepening of the mine infrastructure.

 

The Nexa geological team has continued to conduct exploration activities in the immediate environs of the Vazante Mine as well as in the neighbouring regions. The regional exploration programs have discovered several occurrences of zinc mineralization including Vazante Norte, Carrapato, Vazante Sul, and Sugem.

 

 

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1.3.6 Mineral Resource Estimates

 

The Mineral Resources comprise three styles of mineralization. The first style of mineralization is represented by the hypogene (willemite) mineralized zones that are found in the underground portions of the Vazante and Extremo Norte deposits. The second style of mineralization is represented by the supergene (calamine) mineralized zones found in the Cava 3A, Matas dos Paulistas, and Braquiara areas of the Extremo Norte and Vazante deposits. This supergene (calamine) mineralization is referred to at the Vazante Operation as calamine mineralization and comprises a mixture of smithsonite and hemimorphite minerals. The third type of mineralization comprises tailings that are contained within the Aroeira TSF. The material found in the Aroeira TSF comprise a mixture of hypogene (willemite) and supergene (calamine) minerals.

 

The 2020 year end (YE) Mineral Resources as of December 31, 2020 for the Vazante Operation are presented in Table 1-2. Mineral Resources have been classified in accordance with the definitions for Mineral Resources in S-K 1300, which are consistent with CIM (2014) definitions. The Mineral Resources are exclusive of Mineral Reserves. The Mineral Resource statements for the underground hypogene (willemite) mineralization are prepared within reporting panels that have been created so as to achieve the required spatial continuity, cut-off grade, and minimum width criteria. The Mineral Resource statements for the supergene (calamine) mineralization are prepared using an open pit shell. The Mineral Resource statements for the tailings are reported using the original topographic surface as a constraint.

 

Table 1-2:            Summary of Mineral Resources as of December 31, 2020

Nexa Resources S.A. – Vazante Polymetallic Operations

 

        Tonnes     Grade     Contained Metal  
Category   Area   (000 t)     (% Zn)     (% Pb)     (g/t Ag)     (000 t Zn)     (000 t Pb)     (000 oz Ag)  
    Vazante & Extremo Norte     3,400       6.91       0.18       8.4       235.0       6.2       918  
Measured   Calamine     0       0.00       0.00       0.0       0.0       0.0       0  
    Tailings     0       0.00       0.00       0.0       0.0       0.0       0  
Subtotal, Measured         3,400       6.91       0.18       8.4       235.0       6.2       918  
                                                             
    Vazante & Extremo Norte     2,000       5.84       0.13       7.6       117.0       2.6       489  
Indicated   Calamine     880       9.13       0.16       1.2       80.3       1.4       34  
    Tailings     0.00       0.00       0.00       0.0       0.0       0.0       0.0  
Subtotal, Indicated         2,880       6.85       0.14       5.6       197.3       4.0       523  
                                                             
    Vazante & Extremo Norte     5,400       6.52       0.16       8.1       352.0       8.8       1,407  
Meas. & Ind.   Calamine     880       9.13       0.16       1.2       80.3       1.4       34  
    Tailings     0.00       0.00       0.00       0.0       0.0       0.0       0.0  
Subtotal, M&I         6,280       6.88       0.16       7.1       432.3       10.2       1,441  
                                                             
    Vazante & Extremo Norte     9,040       7.79       0.17       11.0       704.0       14.9       3,190  
Inferred   Calamine     870       9.92       0.09       1.1       86.3       0.8       31  
    Tailings     3,939       4.06       0.25       7.8       159.9       9.8       995  
Subtotal, Inferred         13,849       6.86       0.18       9.5       950.2       25.5       4,216  

 

 

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Notes:

 

1. The definitions for Mineral Resources in S-K 1300 were followed for Mineral Resources which are consistent with CIM (2014) definitions.
2. Mineral Resources are reported on a 100% ownership basis.
3. Mineral Resources are estimated at various NSR cut-off values appropriate to the mineralization style.
4. Mineral Resources are estimated using average long term metal prices of Zn: US$2,869.14/t (US$1.30/lb), Pb: US$2,249.40/t (US$1.02/lb), and Ag: US$19.38/oz, and metallurgical recoveries are based on recovery curves derived from historical processing data. An average long term Brazilian Real (R$)/US$ exchange rate of 4.84 was used.
5. A minimum mining width of 3.0 m was used to create Mineral Resource reporting shapes for the willemite mineralization.
6. Mineral Resources are exclusive of Mineral Reserves.
7. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability.
8. Numbers may not add due to rounding.

 

The SLR QP is of the opinion that, with consideration of the recommendations summarized in this section, any issues relating to all relevant technical and economic factors likely to influence the prospect of economic extraction can be resolved with further work.

 

1.3.7 Mineral Reserve Estimates

 

The Vazante Operation Mineral Reserves are based in three main orebodies: Lumiadeira, Sucuri, and Extremo Norte. The main commodities produced are zinc, lead, and silver. The Mineral Reserve estimate for the Vazante Operation as of December 31, 2020 is presented in Table 1-3.

 

Table 1-3:            Summary of Mineral Reserves as of December 31, 2020

Nexa Resources S.A. – Vazante Polymetallic Operations

 

    Tonnes     Grade     Contained Metal  
Deposit/Category   (000 t)     (% Zn)     (% Pb)     (g/t Ag)     (000 t Zn)     (000 t Pb)     (000 oz Ag)  
Lumiadeira                                                        
Proven     3,410       8.93       0.22       20.78       304.5       7.6       2,278  
Probable     3,260       8.86       0.22       18.44       289.0       7.2       1,933  
Proven & Probable     6,670       8.90       0.22       19.64       593.5       14.8       4,211  
                                                         
Sucuri                                                        
Proven     3,408       8.41       0.26       13.74       286.8       9.0       1,505  
Probable     1,225       7.17       0.26       11.40       87.9       3.2       449  
Proven & Probable     4,633       8.09       0.26       13.12       374.7       12.3       1,954  
                                                         
Extremo Norte                                                        
Proven     1,621       7.25       0.24       6.57       117.5       4.0       342  
Probable     3,760       9.34       0.18       7.11       351.0       6.9       860  
Proven & Probable     5,381       8.71       0.20       6.95       468.6       10.9       1,202  
                                                         
Total                                                        
Proven     8,439       8.40       0.24       15.20       708.8       20.6       4,125  
Probable     8,245       8.83       0.21       12.23       727.9       17.4       3,241  
Proven & Probable     16,684       8.61       0.23       13.73       1,436.7       38.0       7,367  

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Notes:

 

1. The definitions for Mineral Reserves in S-K 1300 were followed for Mineral Reserves which are consistent with CIM (2014) definitions.
2. Mineral Reserves are estimated at a cut-off NSR value of US$47.49/t processed.
3. Mineral Reserves are estimated using average LOM metal prices of US$2,494.90/t Zn, US$1,956.00/t Pb and US$16.85/oz Ag and a R$/US$ exchange rate of 4.84.
4. A minimum mining width of 4.0 m was used.
5. Bulk density is 3.1 t/m3.
6. Numbers may not add due to rounding.

 

Contained metal in the Mineral Reserves consists of 1.44 Mt Zn, 38,000 t Pb, and 7.37 Moz Ag.

 

The SLR QP is not aware of any risk factors associated with, or changes to, any aspect, of the modifying factors such as mining, metallurgical, infrastructure, permitting, or other relevant factors that could materially affect the Mineral Reserve estimate.

 

1.3.8 Mining Methods

 

The Vazante Operation consists of two mechanized underground mines, the Vazante Mine and Extremo Norte Mine, currently operating at a rate of approximately 1.5 Mtpa. The mineralized zones dip between 45° and 70° and the mine extends over a strike length of five kilometres. With the addition of the North Extension, this will increase to approximately 10 km. The Vazante Mine currently extends over a vertical depth of 300 m from surface to the 326 level. The Vazante Mine is being deepened by 186 m to the planned 140 level. There are former open pits along portions of the strike of the Vazante deposit.

 

There are two access ramps to the Vazante Mine and one to the Extremo Norte Mine. Mine headings range from 5 m high by 4.5 m wide ore drives to 6 m high by 5 m wide main ramps.

 

The Vazante Operation is designed based upon mechanized longitudinal longhole stoping for areas with a dip greater than 45°. Longhole stopes are developed with footwall access drives parallel to the orebody. Crosscuts are driven from the footwall drive and then the ore is developed along strike. Sublevels are typically 30 m apart though the distance varies depending on the orebody. Long holes are often a combination of downholes or VRM and uppers or sublevel longhole open stopes (SLOS). Both longhole methods employ a retreat sequence along strike. The SLOS stopes are not backfilled whereas the VRM stopes are backfilled.

 

 

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1.3.9 Processing and Recovery Methods

 

The Vazante Operation currently processes ore in which the main zinc mineral is willemite, a zinc silicate mineral (Zn2SiO4). During earlier Vazante operations the predominant zinc mineralization occurred as calamine, which consists of both smithsonite (ZnCO3) and hemimorphite (Zn4Si2O7(OH)H2O). Processing consists of crushing, grinding, and flotation, resulting in the production of a zinc silicate concentrate and small quantities of lead sulphide concentrate. Calamine ore has not been produced or processed since 2008. Treatment of calamine ores was more challenging than willemite ores with zinc recovery from calamine ores typically only approximately 50%, while zinc recovery from willemite ores typically ranges from approximately 81% to 91%. Recent zinc recovery to concentrate (2017 to 2020) has ranged from 84% to 87%.

 

Zinc is the primary metal of economic importance, with minor quantities of lead as galena and associated silver minerals allowing for the production of relatively small amounts of lead concentrate as well. The Vazante Operation produces approximately 350,000 tonnes per annum (tpa) to 370,000 tpa of zinc concentrate and approximately 4,000 tpa to 5,000 tpa of lead concentrate that contains silver. Due to the ore mineralogy, zinc concentrate produced at the Vazante Operation is elevated in silica, calcium, magnesium, and carbonates resulting from the presence of carbonate gangue (predominantly dolomite). Nexa’s Três Marias zinc smelter includes a processing circuit specifically configured to process the zinc silicate concentrate produced at the Vazante Operation and as a result, all of the concentrate produced at the Vazante Operation is processed at the Três Marias smelter where zinc metal is produced. The lead concentrate produced at the Vazante Operation is sold on the open market.

 

1.3.10 Infrastructure

 

The surface and underground infrastructure of the Vazante Operation include:

 

· Seven historic open pit mines that have exploited the near-surface calamine mineralization.

 

· Two underground mines (Vazante and Extremo Norte) that together extend for a strike length of approximately nine kilometres and to a depth of approximately 550 m from surface.

 

· An ore blending and reclaim facility.

 

· Two processing plants, Plant W and Plant C. Plant W has a nominal throughput capacity of 1.2 Mtpa and Plant C has a nominal throughput capacity of 0.4 Mtpa.

 

· Several TSFs (two active).

 

· A core logging and sampling facility.

 

· Warehousing.

 

· An assay laboratory.

 

· A millwright and electrical shop.

 

· An administrative building.

 

· A first aid station.

 

The power supply to the Vazante Operation is provided by two independent 138 kV transmission lines that feed the site and that can provide up to 55 MW.

 

 

 

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1.3.11 Market Studies

 

1.3.11.1 Zinc Concentrate

 

Due to the ore mineralogy, zinc concentrate produced at the Vazante Operation is elevated in silica, calcium, magnesium, and carbonates resulting from the presence of carbonate gangue (predominantly dolomite). Recovery of zinc metal from zinc silicate concentrates is quite different compared to recovery from sulphides, requiring hydrometallurgical processing at a dedicated facility such as Nexa’s Três Marias smelter. The Três Marias zinc smelter includes a processing circuit specifically configured to process the zinc silicate concentrate produced at the Vazante Operation and, as a result, all of the concentrate produced at the Vazante Operation is processed at the Três Marias smelter where zinc metal is produced. The Vazante Operation concentrate accounts for approximately 70% of the feed to the Três Marias smelter. Deleterious elements affecting the Três Marias smelting operation are controlled at the Vazante Operation to ensure that they do not exceed the limits imposed by the smelter.

 

1.3.11.2 Lead Concentrate

 

Nexa provided information regarding sales contracts for lead concentrate produced at the Vazante Operation. According to this information, sales contracts are in place with concentrate traders for the sale of the lead concentrate and are considered to be consistent with industry norms. Since the lead concentrate produced at the Vazante Operation contains less than the preferred 45% lead (typically the concentrate contains approximately 23% lead), the concentrate is subject to a small penalty charge, reported by Nexa to be less than $1.00/t.

 

1.3.12 Environmental Studies, Permitting and Plans, Negotiations, or Agreements with Local Individuals or Groups

 

The Vazante Operation has a net positive water balance that results in surplus water collected onsite being discharged to the receiving environment. Industrial effluents from the Vazante Operation are directed to the Aroeira TSF, together with surface runoff from the crushing area, chemical laboratory area, and channel network for surface water collection. Underground mine dewatering is pumped to surface and conveyed via gravity to the Aroeira TSF tailings pond through a concrete channel. Water is pumped from the Aroeira TSF to offset make up water requirements for ore processing. Excess water collected in the Aroeira TSF is released to the Santa Catarina River. Dewatering from the Extremo Norte Mine is pumped to a sediment sump prior to release to the Ouro Podre stream.

 

Tailings are currently disposed in the Pilha Garrote DSTSF as filtered tailings, and at the Aroeira TSF as a slurry. The Pilha Garrote DSTSF is the primary TSF. Waste rock is used for backfilling or disposed of at surface in mined-out open pits.

 

Six Environmental Impact Assessments (EIAs) complemented with other studies have been developed since 2000 to identify potential environmental effects resulting from project activities for the construction, operation, and closure stages. The mitigation measures are mostly addressed through a number of environmental control programs (including environmental monitoring) presented in the EIAs.

 

The Vazante Operation holds several permits in support of the current operations. The main instrument to regulate the Vazante Operation is a set of operating licences issued by the COPAM from the state of Minas Gerais. The licences are active, some of them under renewal process.

 

 

 

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Two annual environmental reports (one for the Vazante Mine and one for the Extremo Norte Mine) were prepared by Nexa in 2020 and submitted to the authority (Regional Environment Superintendence SUPRAM-NOR) in compliance with Condition 01 of the Operation Licences.

 

The closest community is the municipality of Vazante, located 8.5 km from the Vazante Operation with a population of approximately 20,600 residents. The closest major urban centre is Brasilia, approximately five hours away via roadways (250 km), with a population of approximately 4.7 million residents.

 

The most recent Mine Closure Plan was prepared in 2018. The Mine Closure Plan has been designed to address remediation of the operational areas, and to meet Brazilian engineering requirements for such plans at a conceptual level. The plan identifies three key phases: pre-closure, closure, and post-closure. Most facilities will be dismantled, and equipment removed from the site. Underground openings will be sealed, and groundwater levels allowed to stabilize.

 

Closure of the Aroeira TSF will involve removal of the tailings pond, construction of an outlet channel, decommissioning of the operating spillway, placing of topsoil on the deposited tailings surface and revegetation. Closure of the Pilha Garrote DSTSF will involve construction of a surface drainage system, placing of topsoil and revegetation. Post-closure monitoring would be undertaken over a 10 year period (conceptually 2029 to 2038), and would include monitoring of geotechnical stability, water quality, fauna, and revegetation.

 

1.3.13 Capital and Operating Cost Estimates

 

Sustaining capital costs were estimated by Nexa, with the majority of the costs consisting of mine development and heavy mobile equipment needed to replace the aging fleet. Sustaining capital costs are summarized in Table 1-4.

 

Table 1-4:               Sustaining Capital Cost Estimate

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Category   Sustaining Costs
(US$ millions)
 
Safety, Health & Environmental     4.8  
Heavy Mobile Equipment     53.9  
Expansion     18.5  
Modernization     6.0  
Horizontal Development     94.7  
Vertical Development     23.6  
Sustaining     27.4  
Operational Working Capital     -7.6  
Closure     38.5  
Total     259.9  

 

Operating costs estimated by Nexa, averaging US$68.6 million per year, were estimated for mining, processing, and general and administration (G&A). Operating cost inputs such as labour rates, consumables, and supplies were based on Nexa operating data. A summary of operating costs is provided in Table 1-5.

 

 

 

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Table 1-5:             Operating Cost Estimate

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Parameter     Total LOM
(US$ millions)
    Average Year
(US$ millions/yr)
    LOM Unit Cost
(US$/t)
 
Mining       447.7       40.7       26.83  
Processing       222.8       20.3       13.36  
G&A       84.5       7.7       5.06  
Total       755.0       68.6       45.25  

 

SLR notes that capital and operating costs are incurred in Brazilian Reais (R$), and that the foreign exchange rate R$:US$ has a significant impact on costs.

 

 

 

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2.0 Introduction

 

SLR Consulting Ltd (SLR) was retained by Nexa Resources S.A. (Nexa) to prepare an independent Technical Report Summary on the Vazante Polymetallic Operations (the Vazante Operation), located in the state of Minas Gerais, Brazil. The purpose of this Technical Report Summary is to support the disclosure of Mineral Resource and Mineral Reserve estimates for the Vazante Operation as of December 31, 2020. This Technical Report Summary conforms to United States Securities and Exchange Commission’s (SEC) Modernized Property Disclosure Requirements for Mining Registrants as described in Subpart 229.1300 of Regulation S-K, Disclosure by Registrants Engaged in Mining Operations (S-K 1300) and Item 601 (b)(96) Technical Report Summary.

 

Nexa is a publicly traded company on the Toronto Stock Exchange (TSX) and the New York Stock Exchange (NYSE). Nexa is a reporting issuer in all provinces and territories of Canada and is under the jurisdiction of the Ontario Securities Commission.

 

Nexa is a large-scale, low-cost, integrated zinc producer with over 60 years of experience developing and operating mining and smelting assets in Latin America. Nexa has a diversified portfolio of polymetallic mines (zinc, lead, copper, silver, and gold) and also greenfield projects at various stages of development in Brazil and Peru. In Brazil, Nexa owns and operates two underground mines, Vazante and Morro Agudo (Zn and Pb). It also operates two zinc smelters in Brazil (Três Marias and Juiz de Fora). In Peru, Nexa operates the El Porvenir (Zn, Pb, Cu, and Ag, Cerro Lindo (Zn, Cu, Pb, and Ag), and Atacocha (Zn, Cu, Pb, Au, and Ag) mines, as well as the Cajamarquilla zinc smelter near Lima. Nexa’s development projects in Peru include Magistral, Shalipayco, Florida Canyon (JV with Solitario), Hilarión, and Pukaqaqa. In Brazil, Nexa is developing the Aripuanã Zinc Project (Zn, Pb, Cu, Au, and Ag), which is currently under construction.

 

2.1 Site Visits

 

A site visit was carried out to the Vazante Operations by SLR Qualified Persons (QP) from November 19 to 23, 2018. During this site visit, the SLR QPs visited the core shack where examples of the mineralization from both the Vazante and Extremo Norte deposits were inspected, logging and sampling procedures reviewed, and visits carried out to the sample sawing and density measurement facilities. Visits were made to several locations in the underground mines in which the nature of the mineralization was observed and the grade control mapping and sampling procedures were discussed. SLR QPs also visited some of the mine stockpile areas, in addition to conducting a tour of the processing plant to inspect the sampling points used to determine the tonnages and grades processed. A visit was made to the site sample preparation facility as well as the site assay laboratory. Discussions were held with site personnel as noted below.

 

2.2 Sources of Information

 

During the preparation of this Technical Report Summary, discussions were held with the following Nexa personnel:

 

· Mr. Thiago Nantes Teixeira, Mineral Resources and Mineral Reserves Committee

 

· Ms. Priscila Artioli, Mineral Resources and Mineral Reserves Committee

 

· Mr. Fernando Madeira Perisse, Technical Services Manager

 

· Mr. Jorge Lucas Carvalho Bechir, Technology Manager

 

 

 

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· Mr. Thiago De Oliveira Nunan Leite, Metallurgical Plant Manager

 

· Mr. Anibal Pereira Neto, Metallurgical plant Coordinator

 

· Mr. Jose Antonio Lopes, Resource Manager

 

· Mr. Thiago Rolla Nunes, Geology Coordinator

 

· Ms. Michele Rodriguez, Financial Analyst

 

· Ms. Barbara Nassif Veiga, Senior Geologist

 

· Mr. Leonardo Hiram Nunez, Geology Consultant

 

· Mr. Helber Tomazella, Mineral Exploration Manager

 

· Mr. Rafael Fernandes de Freitas, Geology Consultant

 

· Mr. Paulo Calazans, Mining Engineering Consultant

 

· Mr. Frederico Costa Melo, Mining Engineering Consultant

 

· Ms. Marianita Rojas Solorzano, Mine Planning Engineer

 

· Mr. Luiz Fernando de Oliveira Silva, Environmental Engineer

 

· Mr. Volvei Tenfen, Environmental Manager

 

· Mr. Vitor Ferraz Viana, Technical Services Manager

 

· Mr. Edmar Eufrasio de Araujo, Geology Consultant

 

· Ms. Aline Vilas Boas de Souza, Social Consultant

 

This Technical Report Summary was prepared by SLR. No prior Technical Report Summaries have been filed in respect to the Vazante Operations.

 

The documentation reviewed, and other sources of information, are listed at the end of this Technical Report Summary in Section 27 References.

 

 

 

Nexa Resources S.A.│Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000
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2.3 List of Abbreviations

 

Units of measurement used in this Technical Report Summary conform to the metric system. All currency in this Technical Report Summary is US dollars (US$) unless otherwise noted.

 

m   micron   kVA   kilovolt-amperes
             
mg   microgram   kW   kilowatt
             
a   annum   kWh   kilowatt-hour
             
A   ampere   L   litre
             
bbl   barrels   lb   pound
             
Btu   British thermal units   L/s   litres per second
             
°C   degree Celsius   m   metre
             
C$   Canadian dollars   M   mega (million); molar
             
cal   calorie   m2   square metre
             
cfm   cubic feet per minute   m3   cubic metre
             
cm   centimetre   MASL   metres above sea level
             
cm2   square centimetre   m3/h   cubic metres per hour
             
d   day   mi   mile
             
dia   diameter   min   minute
             
dmt   dry metric tonne   mm   micrometre
             
dwt   dead-weight ton   mm   millimetre
             
°F   degree Fahrenheit   mph   miles per hour
             
ft   foot   MVA   megavolt-amperes
             
ft2   square foot   MW   megawatt
             
ft3   cubic foot   MWh   megawatt-hour
             
ft/s   foot per second   oz   Troy ounce (31.1035 g)
             
g   gram   oz/st, opt   ounce per short ton
             
G   giga (billion)   ppb   part per billion
             
Gal   Imperial gallon   ppm   part per million
             
g/L   gram per litre   psia   pound per square inch absolute
             
Gpm   Imperial gallons per minute   psig   pound per square inch gauge
             
g/t   gram per tonne   RL   relative elevation
             
gr/ft3   grain per cubic foot   s   second
             
gr/m3   grain per cubic metre   st   short ton
             
ha   hectare   stpa   short ton per year
             
hp   horsepower   stpd   short ton per day

 

 

Nexa Resources S.A.│Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000
Technical Report Summary - February 15, 2021

 

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hr   hour   t   metric tonne
             
Hz   hertz   tpa   metric tonne per year
             
in.   inch   tpd   metric tonne per day
             
in2   square inch   US$   United States dollar
             
J   joule   USg   United States gallon
             
k   kilo (thousand)   USgpm   US gallon per minute
             
kcal   kilocalorie   V   volt
             
kg   kilogram   W   watt
             
km   kilometre   wmt   wet metric tonne
             
km2   square kilometre   wt%   weight percent
             
km/h   kilometre per hour   yd3   cubic yard
             
kPa   kilopascal   yr   year

 

 

 

Nexa Resources S.A.│Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000
Technical Report Summary - February 15, 2021

 

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3.0 Property Description

 

3.1 Location

 

The Vazante Operation is located in the western portion of the state of Minas Gerais, Brazil at a latitude of approximately 17° 57’ 33” S and a longitude of approximately 46° 49’ 42” W, within Zone 23S of the Universal Transverse Mercator (UTM) coordinate system (Cόrrego Alegre Datum) at approximately 306,000 mE and 8,016,000 mN (Figure 3-1). The Vazante Operation is located approximately 8.5 km east of the town of Vazante, 253 km southeast of Brasilia, and 370 km northwest of Belo Horizonte.

 

The zinc concentrate produced at the Vazante Operation is transported to Nexa’s Três Marias smelter complex for further processing while lead concentrate is sold on the open market.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Figure 3-1:       Location Map

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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3.2 Land Tenure

 

3.2.1 Introduction

 

Title to the Vazante Operation is held by Nexa Recursos Minerais S A (Nexa Brazil) and Mineração Soledade Ltda., a subsidiary of Nexa Brazil. The mineral title for the Vazante Operation includes a number of mining concessions and exploration authorizations that are dispersed over a large area measuring approximately 60 km in a north-south direction and approximately 35 km in an east-west direction. Two exploration authorizations held by Vale S.A. under a joint venture contract also form part of the land tenure

 

Mining activities in Brazil are governed by the Brazilian Federal Constitution of 1988 (the Brazilian Federal Constitution), the Brazilian Mining Code (Federal Decree-Law No. 227/1967), and various other decrees, laws, ordinances, and regulations such as the Decree number 9.406/2018 which renews the regulation of the Mining Code. These regulations impose several obligations on mining companies relating to such items as the manner in which mineral deposits are exploited, the health and safety of the workers and local communities where mines are located, and environmental protection and remediation measures.

 

Under the Brazilian Federal Constitution, mineral rights are recognized to belong exclusively to the Brazilian federal government and are recognized as being distinct from surface rights. The Brazilian federal government is the sole entity that is responsible for governing mineral exploration and mining activities in Brazil.

 

Amongst other ministries and agencies, the Ministry of Mines and Energy (MME) and the Agência Nacional de Mineração (ANM) (formerly the Departamento Nacional de Produção Mineral (DNPM)) regulate mining activities in Brazil. The ANM is responsible for monitoring, analyzing, and promoting the performance of the Brazilian mineral industry by administering and granting rights related to the exploration and exploitation of mineral resources and other related activities in Brazil.

 

In Brazil, tenure to the mineral resources is achieved via exploration licenses (Autorizações de Pesquisa), mining concessions (Concessões de Lavra), mining concession applications (Requerimento de Lavra), and exploration license applications (Requerimentos de Pesquisa), which are together broadly referred to as mineral rights.

 

3.2.2 Mining Concessions

 

Mining concessions have no set expiry date. Each year Nexa is required to provide information to ANM summarizing mine production statistics through the annual mining report (Relatório Anual de Lavra). The perimeter of the mining concessions is defined by detailed surveys according to the conditions outlined by dos Santos et. al. (2016). Any tailings derived from mineral production from mining concessions are considered to be a part of the minerals produced from the mining concessions.

 

In addition, it should be noted that several mining concessions from the same holder and of the same mineral substance, in areas of the same deposit or mineralized zone, may be combined in a single mining unit, under the name of Group of Mining Concessions. According to the Mining Code and its Regulation (Decree nos. 227/1967 and 9.406/2018), the Group of Mining Concessions must be granted by the ANM and its holder, at the discretion of ANM, and may concentrate mining activities in one or some of the grouped concessions provided that the intensity of the mining is compatible with the importance of the total reserve of the grouped deposits.

 

Nexa holds a number of mining concessions throughout the Project area that total 2,091.10 ha. They are located as a group of six mining concessions in the immediate mine area and two other mining concessions that are dispersed elsewhere throughout the land package (Table 3-1). Figure 3-2 presents the location of the Vazante Operation mining concessions and mineralization.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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In addition, the land holdings include an additional 272.18 ha comprising one mining application (ANM Register ID 5280/1956), one Right to Apply for Mining Concession (ANM Register ID 831875/2006), and one additional mining concession (ANM Register ID 801603/1968).

 

Table 3-1:                    List of Mining Concessions, Mining Applications, and Right to Apply for Mining Concessions

Nexa Resources S.A. – Vazante Polymetallic Operations

 

ANM Register ID   Status   Area
(ha)
 
1032/1955   Mining Concession     73.19  
1034/1955   Mining Concession     76.71  
1035/1955   Mining Concession     47.89  
1036/1955   Mining Concession     276.25  
1973/1962   Mining Concession     412.39  
2664/1956   Mining Concession     119.00  
805141/1976   Mining Concession     859.17  
14840/1967   Mining Concession     226.50  
Subtotal         2,091.10  
             
5280/1956   Mining Application     189.98  
831875/2006   Right to Apply for Mining Concession     29.70  
801603/1968   Mining Concession     52.50  
Subtotal         272.18  
Grand Total         2,363.28  

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Figure 3-2:     Location of Mining Concessions and Mineralization

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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3.2.3 Exploration Licenses

 

Surrounding the mining concessions, Nexa also holds 62 exploration licenses totalling 50,076.76 ha. The land holdings include one additional parcel comprising a Right to Apply for Mining Concession with an area of 344.52 ha (Table 3-2). Figure 3-3 presents the location of the Vazante Operation exploration licenses.

 

Exploration licenses are granted for an initial period of three years. Once a company has applied for an exploration license, the applicant holds a priority right to the concession area as long as there is no previous ownership. The fee for holding the licenses during this initial three year phase is Brazilian Reais (R$) 3.55/ha, to be paid annually. The owner of the license can apply to have the exploration license renewed for a one time extension period up to three years. The fee for holding the licenses during the second phase is R$5.33/ha, to be paid annually. Renewal is at the sole discretion of ANM. Granted mining concessions and exploration licenses are published in the Official Gazette of the Republic (Diário Oficial da União - DOU), which lists individual concessions and their change in status. The exploration licenses and mining concessions grant the owner subsurface mineral rights, while surface rights can be applied for if the land is not owned by a third party.

 

The owner of an exploration license is guaranteed, by law, access to perform exploration field work, provided adequate compensation is paid to third party landowners and the owner accepts all environmental liabilities resulting from the exploration work. The exploration licenses are subject to annual fees based on their size (Taxa Anual por Hectare). A final report summarizing the results of any exploration activities carried out is required to be filed with the ANM upon expiry of an exploration license.

 

Table 3-2:      List of Exploration Licenses

Nexa Resources S.A. – Vazante Polymetallic Operations

 

ANM
Register ID
  Area
(ha)
    Status   Titleholder   Expiry Date
(MM/DD/YYYY)
  Extended
Expiry Date
(MM/DD/YYYY)
831260/2018     833.74     Exploration License   Nexa Recursos Minerais S A   9/6/2021   6/21/2022
831259/2018     410.77     Exploration License   Nexa Recursos Minerais S A   9/6/2021   6/21/2022
831258/2018     761.26     Exploration License   Nexa Recursos Minerais S A   9/6/2021   6/21/2022
831194/2018     37.65     Exploration License   Nexa Recursos Minerais S A   9/6/2021   6/21/2022
831176/2018     901.62     Exploration License   Nexa Recursos Minerais S A   9/26/2021   7/11/2022
831106/2018     999.91     Exploration License   Nexa Recursos Minerais S A   10/16/2020   7/31/2022
830365/2018     38.8     Exploration License   Nexa Recursos Minerais S A   3/20/2021   1/2/2022
830343/2018     1,826.87     Exploration License   Nexa Recursos Minerais S A   3/20/2021   1/2/2022
832209/2017     1,612.32     Exploration License   Nexa Recursos Minerais S A   3/23/2021   1/5/2022
832171/2017     1,707.10     Exploration License   Nexa Recursos Minerais S A   3/20/2021   1/2/2022
832170/2017     1,196.36     Exploration License   Nexa Recursos Minerais S A   3/20/2021   1/2/2022
832141/2017     993.52     Exploration License   Nexa Recursos Minerais S A   3/20/2021   1/2/2022
832108/2017     993.58     Exploration License   Nexa Recursos Minerais S A   3/13/2021   12/26/2021

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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ANM
Register ID
  Area
(ha)
    Status   Titleholder   Expiry Date
(MM/DD/YYYY)
  Extended
Expiry Date
(MM/DD/YYYY)
832104/2017     1,000.00     Exploration License   Nexa Recursos Minerais S A   3/13/2021   12/26/2021
832094/2017     472.33     Exploration License   Nexa Recursos Minerais S A   3/13/2021   12/26/2021
832021/2017     835.56     Exploration License   Nexa Recursos Minerais S A   7/26/2021   5/10/2022
832019/2017     1,056.89     Exploration License   Nexa Recursos Minerais S A   7/26/2021   5/10/2022
832018/2017     161.64     Exploration License   Nexa Recursos Minerais S A   3/19/2021   1/1/2022
832017/2017     1,920.26     Exploration License   Nexa Recursos Minerais S A   3/19/2021   1/1/2022
831988/2017     1,947.19     Exploration License   Nexa Recursos Minerais S A   3/13/2021   12/26/2021
830868/2017     714.05     Exploration License   Nexa Recursos Minerais S A   5/25/2021   3/9/2022
830476/2017     1,954.84     Exploration License   Nexa Recursos Minerais S A   2/9/2021   11/24/2021
830467/2017     45.28     Exploration License   Nexa Recursos Minerais S A   3/26/2023   1/1/2024
830466/2017     295.62     Exploration License   Nexa Recursos Minerais S A   3/26/2023   1/1/2024
830465/2017     831.47     Exploration License   Nexa Recursos Minerais S A   4/28/2023   1/1/2024
830464/2017     15.22     Exploration License   Nexa Recursos Minerais S A   4/28/2023   1/1/2024
830463/2017     1,152.64     Exploration License   Nexa Recursos Minerais S A   4/28/2023   1/1/2024
830461/2017     601.53     Exploration License   Nexa Recursos Minerais S A   3/26/2023   1/1/2024
830460/2017     1,359.83     Exploration License   Nexa Recursos Minerais S A   3/26/2023   1/1/2024
832170/2016     10.31     Exploration License   Nexa Recursos Minerais S A   3/26/2023   1/1/2024
831142/2016     689.36     Exploration License   Nexa Recursos Minerais S A   10/9/2021   7/24/2023
831137/2016     377.72     Exploration License   Nexa Recursos Minerais S A   10/9/2021   7/24/2023
830578/2016     914.28     Exploration License   Nexa Recursos Minerais S A   10/9/2022   7/24/2023
830345/2016     1,473.04     Exploration License   Nexa Recursos Minerais S A   4/23/2023   1/1/2024
830344/2016     1,888.30     Exploration License   Nexa Recursos Minerais S A   4/23/2023   1/1/2024
830341/2016     1,651.59     Exploration License   Nexa Recursos Minerais S A   4/23/2023   1/1/2024
830340/2016     1,958.50     Exploration License   Nexa Recursos Minerais S A   5/26/2023   1/1/2024
830339/2016     1,941.37     Exploration License   Nexa Recursos Minerais S A   4/23/2023   1/1/2024
830338/2016     1,793.39     Exploration License   Nexa Recursos Minerais S A   5/26/2023   1/1/2024
830333/2016     804.77     Exploration License   Nexa Recursos Minerais S A   6/9/2023   1/1/2023
831421/2014     130.37     Exploration License   Nexa Recursos Minerais S A   2/3/2023   11/18/2023
831420/2014     193.05     Exploration License   Nexa Recursos Minerais S A   4/15/2023   1/1/2024
830730/2014     30.15     Exploration License   Nexa Recursos Minerais S A   4/2/2022   1/15/2023
832214/2013     133.98     Exploration License   Nexa Recursos Minerais S A   6/28/2021   4/12/2022
831926/2013     311.6     Exploration License   Mineração Soledade Ltda   2/6/2022   11/21/2021
830955/2013     896.45     Exploration License   Nexa Recursos Minerais S A   Pending   Pending

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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ANM
Register ID
  Area
(ha)
    Status   Titleholder   Expiry Date
(MM/DD/YYYY)
  Extended
Expiry Date
(MM/DD/YYYY)
833117/2012     1,000.00     Exploration License   Nexa Recursos Minerais S A   6/28/2021   4/12/2022
832196/2012     206.37     Exploration License   Nexa Recursos Minerais S A   6/28/2021   4/12/2022
831641/2012     857.81     Exploration License   Nexa Recursos Minerais S A   6/28/2021   4/12/2022
831543/2012     143.25     Exploration License   Nexa Recursos Minerais S A   6/28/2021   4/12/2022
832317/2011     44.4     Exploration License   Mineração Soledade Ltda   3/15/2021   12/28/2021
831297/2011     394.78     Exploration License   Mineração Soledade Ltda   10/16/2021   7/31/2022
834685/2010     35.47     Exploration License   Nexa Recursos Minerais S A   6/29/2021   4/13/2022
834682/2010     74.2     Exploration License   Nexa Recursos Minerais S A   2/25/2023   12/10/2022
834681/2010     163.29     Exploration License   Nexa Recursos Minerais S A   2/25/2023   12/10/2022
830676/2010     1,835.06     Exploration License   Nexa Recursos Minerais S A   6/5/2022   3/20/2023
830497/2010     337.7     Exploration License   Nexa Recursos Minerais S A   Pending   Pending
830232/2010     42.1     Exploration License   Nexa Recursos Minerais S A   3/26/2023   1/1/2024
831690/2009     782.02     Exploration License   Nexa Recursos Minerais S A   6/5/2022   3/20/2023
830170/2008     878.13     Exploration License   Nexa Recursos Minerais S A   2/25/2022   12/10/2022
832451/2004     991.72     Exploration License   Vale S A (Joint Venture)   Pending   Pending
832893/2012     414.38     Exploration License   Vale S A (Joint Venture)   8/8/2021   5/23/2021
Total, Expl. Licenses: 62         Total Area: 50,076.76 ha        
                         
832632/2006     344.52     Right to Apply for
Mining Concession
  Nexa Recursos Minerais S A   Pending   Pending

 

Note:

 

1. Due to the COVID-19 pandemic situation, the ANM has extended the deadlines for the expiration of the mineral rights by up to 288 days.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Figure 3-3:       Location of Exploration Concessions

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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3.2.4 Surface Rights

 

In addition to the mineral titles described previously, Nexa also holds title to a number of surface rights for such items as easements, infrastructure footprints, and rights-of-way in the immediate mine area. These surface rights comprise 30 titles that cover a total of 3,243.29 ha (Table 3-3). The location of the surface rights is shown in Figure 3-4.

 

Table 3-3:                 List of Surface Rights

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Real Estate Name   Property Certificate   Area
(ha)
  Mining Right ANM
Fazenda Salobo   4.813   27.84   805141/1976
830093/1988
831022/2006
831543/2012
831137/2016
             
Fazenda Vazantes, Lugar Serra do Poço Verde   5.926   73.02   1032/1955
1034/1955
             
Fazenda Vazantes, Lugar Serra do Poço Verde   5.927   76.48   1032/1955
1034/1955
             
Fazenda Vazantes   6.264   164.48   805141/1976
831695/1990
830943/2011
832170/2016
830461/2017
830466/2017
             
Fazenda Claro, Lugar Cercado   7.686   76.74   801603/1968
830463/2017
830868/2017
             
Fazenda Vazantes   9.277   6.00   805141/1976
             
Fazenda Vazantes   5.496   184.00   831695/1990
830946/2011
833777/2011
832170/2017
830461/2017
830466/2017
832209/2017
831259/2018

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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        Area    
Real Estate Name   Property Certificate   (ha)   Mining Right ANM
Fazenda Salobo   324   95.0   1035/1955
Fazenda Salobo, Lugar Sucuri   1.470   433.77   1034/1955
Fazenda Salobo, Lugar Vargem Grande   1.619   9.0   1036/1955
Fazenda Salobo, Lugar Sucury   2.094   31.0   805141/1976
Fazenda Salobo, Lugar Palmito   2.270   281.40   831695/1990
Fazenda Salobo, Lugar Sucuri or Várzea da Sucuri   2.611   30.00   831022/2006
Fazenda Vanates, Lugar Capão do Cedro ans Serra do Poço  Verde   2.955   87.92   832606/2008
Fazenda Vazantes, Lugar Poço Verde   3.129   115.3   830232/2010
Fazenda Vazantes, Lugar Poço Verde   3.130   9.0   830943/2011
Fazenda Salobo, Lugar Palmito   3.425   122.12   833774/2011
Fazenda Salobo Lugar Rochedo   3.525   32.0   833775/2011
Fazenda Vargem Grande   3.941   23.06   833776/2011
Fazendas Salobo, Santa Barbara and Vazante or Lapa   4.232   322.31   830955/2013
Fazenda Vargem Grande   4.249   12.61   831137/2016
Fazenda Vazantes   4.363   297.70   831170/2016
Fazenda Vargem Grande   4.368   3.27   830460/2017
Fazenda Vazante   5.562   12.10   830461/2017
Fazenda Salobo   4.503   8.42   830466/2017
Fazenda Salobo   5.922   105.00   831259/2018
Fazenda Salobo, Lugar Mata dos Paulista   5.923   18.00    
Fazenda Vazante Lugar Capão do Cedro   5.924   51.49    
Fazenda Vazante Lugar Jaburu and Capão das Ambruanas   5.925   50.52    
Fazenda Carneiro   12.363   483.74    
Total:  30 titles       3,243.29    

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Figure 3-4:    Location of Surface Rights Titles

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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3.3 Encumbrances

 

SLR is not aware of any encumbrances to the property, including current and future permitting requirements and associated timelines, permit conditions, and violations and fines.

 

3.4 Royalties

 

Revenues from mining activities at the Vazante Operation are subject to the Compensação Financieria pela Exploração de Recursos Minerais (CFEM) royalty that is paid to the ANM. The CFEM is a royalty paid on a monthly basis based on the sales value of minerals, net of taxes levied on the respective sale. When the produced minerals are used in its internal industrial processes, the CFEM payment is determined based on the costs incurred to produce them. The CFEM is determined by a reference price of the respective mineral to be defined by the ANM. The applicable rate varies according to the mineral product (currently 2% for zinc, lead, dolomite, and copper). There is also a monthly inspection fee related to the transfer and commercialization of certain minerals in some of the Brazilian states (such as Minas Gerais) known as the Taxa de Fiscalização de Recursos Minerais (TFRM), where the Vazante Operation mining concessions are located.

 

SLR is not aware of any environmental liabilities on the property. Nexa has all required permits to conduct the proposed work on the property. SLR is not aware of any other significant factors and risks that may affect access, title, or the right or ability to perform the proposed work program on the property.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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4.0 Accessibility, Climate, Local Resources, Infrastructure and Physiography

 

4.1 Accessibility

 

The Vazante Operation is well serviced by a series of primary and secondary highways, with access roads to many portions of the Exploration Authorizations. Local access to the Vazante Operation from the nearby town of Vazante is via a well maintained paved road leading directly to the mine gate. Internal access to various portions of the mining concessions is by means of gravel roads.

 

The town of Vazante is accessed via high quality paved roads leading southeastwards from Brasilia to Paracatu and onwards to Vazante, or northwestwards from Belo Horizonte. Both Brasilia and Belo Horizonte are well serviced by commercial airlines that provide a large number of daily flights to both domestic and international locations.

 

4.2 Climate

 

The Vazante Operation is located in the equatorial region of Brazil and the climate in the area is classified as humid subtropical, with average daily maximum temperatures of approximately 30°C in September and March of each year. The average daily minimum temperatures typically occur in June and July and reach a minimum of approximately 13°C .

 

The rainy season typically extends from October through March, with peak rainfall occurring typically in December and January at a rate of approximately 300 mm/month. The dry period typically occurs in April through September.

 

4.3 Local Resources

 

The closest settlement to the Vazante Operation is the municipality of Vazante, with a population of approximately 20,600. The main economic activities of the region include cattle raising, farming, and mining. Most of the mine employees reside in Vazante and commute to the mine site daily, a distance of approximately eight kilometres. Goods and services in support of mining operations are generally sourced from Belo Horizonte. The region is well serviced with electricity supplied from the national grid as well as modern telecommunications. Basic medical services are available in the town of Vazante, with higher levels of medical services available in Paracatu, Brasilia, or Belo Horizonte.

 

4.4 Infrastructure

 

The surface and underground infrastructure of the Vazante Operation include:

 

· Seven open pit mines that have exploited the near-surface calamine mineralization.

 

· Two underground mines (Vazante and Extremo Norte) that together extend for a strike length of approximately nine kilometres and to a depth of approximately 550 m from surface.

 

· An ore blending and reclaim facility.

 

· Two processing plants, Plant W and Plant C. Plant W has a nominal throughput capacity of 1.2 million tonnes per annum (Mtpa) and Plant C has a nominal throughput capacity of 0.4 Mtpa.

 

· Waste rock storage facilities.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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· Several tailings storage facilities (TSFs) (two active).

 

· A core logging and sampling facility.

 

· A commissary.

 

· A warehouse.

 

· An assay laboratory.

 

· A millwright and electrical shop.

 

· An administrative building.

 

· A first aid station.

 

The power supply to the Vazante Operation is provided by two independent 138 kV transmission lines that feed the site and that can provide up to 55 MW. Infrastructure is discussed further in Section 18 of this Technical Report Summary.

 

4.5 Physiography

 

The topography in the Vazante Operation area is characterized by gently rolling hillsides with incised streams and rivers. The elevations of the Vazante Operation area ranges from approximately 690 metres above mean sea level (masl) to 970 masl.

 

The majority of the region is used for either farming purposes or for pasture, with the primary food items produced being rice, beans, soybeans, and manioc. Remnant vegetation typically consists of open savannah (cerrado) with gallery type forest cover in the riparian areas. Cerrado is a protected environment, where it occurs.

 

The main water courses in the area form tributaries to the Paracatu River, which is part of the São Francisco River basin. The Santa Caterina River cuts through the southern part of the Vazante Operation area.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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5.0 History

 

5.1 Prior Ownership

 

Mineralization in the Vazante Operation area was initially discovered by Angelo Solis in 1933 who acquired the first mineral titles to the area. The mineral rights to the Vazante Mine portion of the Vazante Operation land holdings were first acquired by Companhia Mineira de Metais (CMM) in 1956. CMM later became Votorantim Resources in 2005 and more recently Nexa Resources S.A. in 2014. The original land titles for the Vazante Operation were added and expanded over the years by means of direct land acquisition (claim staking) and various option agreements and purchases. The Extremo Norte Mine portion of the current Vazante Operation land holdings was acquired by purchase in 2007.

 

5.2 Exploration and Development History

 

The exploration and development history of the Vazante Operation is presented in Table 5-1. The exploration and development work carried out on the property to date has focussed on the location and delineation of the known mineralized zones both along strike and to depth. In addition, exploration work has focussed on evaluating the potential of selected areas on the mineral claims for hosting additional mineralized zones. Exploration work has included basic geologic mapping activities, geochemical and geophysical surveys, and various drilling programs.

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Table 5-1:     Summary of Exploration and Development History

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Year   Operator   Purpose   Summary of Work   Remarks  
                   
1933   Angelo Solis         Zinc discovered in the Vazante region.
               
1956   CMM         Votorantim/Nexa company established.
               
1969   U.S. Steel  

Surface exploration

 

Open pit mining

  Geological Mapping

Regional geological mapping-Cia Meridonal.

 

First ore transported from Vazante open pits to the Três Marias smelter.

               
1972   DOCEGEO   Surface exploration   Geological mapping Regional mapping of the Vazante belt.
               
1974-1978   ENJEX/DOCEGEO/CMM
(Votorantim)/DNPM
  Drilling   Exploratory drilling and mineral potential definition Agua Doce and Pasto prospects.
               
1980-1989   CMM/BSHELL   Drilling   Exploratory drilling and mineral potential definition Agua Doce and Pasto prospects.
               
1983   CMM (Votorantim)   Underground Mining     Commencement of underground mining, Lumiadeira mine.
               
1990   CMM (Votorantim)   Drilling   Exploration drilling Agua Doce prospect.
               
2000   CMM (Votorantim)   Surface exploration   Stream sediment sampling Sampling of the Garrote Formation along the Lagoa Feia trend, and around the Lages, Cercado, and Partecal targets.
               
2001   COMIG   Geophysics   Aerial magnetic and radiometric surveys Vazante belt.
               
2004-2006   Votorantim (CMM became Votorantim in 2005)   Surface exploration drilling   Regional mapping, exploration and resource definition drilling, exploratory auger drilling Olho D’Água target.
               
2007   Votorantim  

Surface exploration

 

 

 



Drilling

 

Regional scale geological mapping (1:100,000) and
local scale mapping (1:20,000) rock sampling

 

 

 

Mineral potential definition

Mapping to identify potential areas of mineralization and better understand the stratigraphic and metallogenetic context around Vazante Mine targets.

 

 

Olho D’Água prospects.

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Year   Operator   Purpose   Summary of Work   Remarks  
                   
2008   Votorantim   Surface exploration   Regional scale geological mapping (1:100,000) and local scale mapping (1:20,000) rock sampling Identify potential areas of mineralization.  Rock and geochemical sampling at Cercado and Olh D’Água prospects.
               
2009   Votorantim  

Surface exploration

 

 

 

Geophysical surveying

 

Regional scale geological mapping (1:100,000) and local scale mapping (1:20,000) rock, soil, and stream sediment sampling

 

Ground magnetic surveys

Identify potential areas of mineralization and infill drilling in the Cercado, Olhos D’Água, and the Lagoa Feia trend.

 

Ground magnetic surveying at the Agua Doce, Extremo Notre Mine, Vazante Mine, and the Lagoa Feia trend.

               
2010   Votorantim  

Surface exploration

 

 

 

 

 

Drilling

 

Regional scale geological mapping (1:100,000) and local scale mapping (1:20,000) rock, soil, and stream sediment sampling

 

 

 

Exploration drilling and mineral potential definition

Large scale geological mapping campaign to assess the mineral potential definition in the Vazante South belt, soil sampling over prospective targets such as Olho D’Água trend, Vazante Mine area, and Cercado trend.

 

 

Focus on drilling over the Cercado trend.

               
2011   Votorantim  

Surface exploration

 

 

 

 

 

Drilling

 


Geophysics

 

Regional scale geological mapping (1:100,000) and local scale mapping (1:20,000) rock, soil, pan concentrate, and stream sediment sampling

 

 

 

Exploration drilling and mineral potential definition

 


FALCON airborne magnetic and gravity surveys

Large scale geological mapping campaign to assess mineral potential definition in the Vazante South belt, soil sampling over prospective targets such as Olho D’Água trend, Vazante Mine area, and Cercado trend.

 

 

Vazante Mine, Olho D’Água, Boi Branco.

 


Regional airborne surveys.

               
2012   Votorantim  

Surface exploration

 



Drilling

 

Regional scale geological mapping (1:100,000, rock, pan concentrate, and stream sediment sampling

 

Exploration drilling and mineral potential definition

Potential areas definition.  Detailed work over the Olho D’Água, Lagoa Feia, Partecal trend and Boi Branco prospect.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Year   Operator   Purpose   Summary of Work   Remarks  
                   
2013   Votorantim  

Surface exploration

 


Drilling

 

Regional scale geological mapping (1:100,000, rock, pan concentrate, and stream sediment sampling

 

Exploration drilling and mineral potential definition

Cercado trend and Boi Branco prospect.

 


Testing potential Vazante parallel structure and Agua Doce prospect.

               
2014   Votorantim (Nexa)  

Surface exploration

 

 

 

Drilling

 


Geophysics

 

Regional, local, and detailed scale geological mapping (1:100,000, 1:20,000 and 1:5,000), rock and pan concentrate sampling

 

Exploratory drilling

 


Electroresistivity surveys

Potential area definition in parallel structure to the Vazante Mine.

 


Olhos D’Água trend, Vazante Mine parallel structures trend.

 

Undertaken to delineate weathering zone and fracture zones at Vazante Mine limits.

               
2015   Nexa  

Surface exploration

 

 

 

Drilling

 

Regional and local scale geological mapping (1:100,000 and 1:20,000), rock, soil, stream sediment, and pan concentrate sampling

 

Exploratory drilling, mineral resource potential and resource definition.

Boi Branco, Lages, Partecal, Olhos D’Água trend.

 

 

 

Vazante Mine parallel structures.

               
2016   Nexa  

Surface exploration

 

Drilling

 

Geophysics

 

Detail-scale mapping (1:10,000), rock and soil sampling

 

Exploratory drilling, mineral potential, and resource definition

 

Induced Polarization (IP) survey

Detail-scale geological mapping at Lages and Lagoa Feia.

 

Vazante Mine drilling (Lumiadeira Sul, gaps at Extremo Norte, and Lages.

 

Spectral IP at Lages, Extremo Norte target and Boi Branco trend.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Year   Operator   Purpose   Summary of Work   Remarks  
                   
2017   Nexa  

Surface exploration

 


Drilling

 

 

 

Geophysics

 

Detail-scale mapping (1:10,000), rock and soil sampling

 

Exploratory drilling, mineral potential, and resource definition

 

 


IP survey

Lages and Lagoa Feia targets.

 


Drilling at Vazante (Lumiadeira Sul, gaps at Extremo Norte and Lages). Beginning of drilling program to assess calamine potential in Vazante Mine.

 

Spectral IP survey over Vazante, Lages, and Lagoa Feia target.

               
2018   Nexa  

Surface exploration


 


Drilling

 

  

Geophysics

 

Detail-scale mapping (1:10,000), rock and soil sampling

 

Exploratory drilling, mineral potential, and resource definition

 

 


IP survey and electrical survey

Lagoa Feia, Cercado, Carrapato, and Calamina targets

 

Vazante Mine drilling (Lumiadeira and gaps at Extremo Norte), Lagoa Feia, Cercado, and Calamina targets.

 

Spectral IP at Carrapato trend, electrical survey at Calamina target.

               
2019   Nexa  

Surface exploration

 

 


Drilling

 

 

 

Geophysics

 

Detail-scale mapping (1:10,000), rock and soil sampling

 

Exploratory drilling, mineral potential, and resource definition

 

 

 


IP survey and electrical survey

Vazante Sul, Sungem, and Calamina targets.

 


Vazante Mine drilling (Extremo Norte, Extremo Norte Deep, and Varginha Norte), Cercado trend, Vazante Sul, and Sungem target.

 

 

Electrical survey at Calamina target.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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5.3 Historical Resource Estimates

 

Nexa has owned the Vazante land holdings and the Vazante Operation since 1956, formerly as CMM, then Votorantim Resources, and more recently as Nexa Resources S.A. There have been no relevant Mineral Resource or Mineral Reserve estimates prepared by previous owners of the Vazante Operation.

 

Additional descriptions of previous Mineral Resource and Mineral Reserve estimates prepared by Nexa are presented in the Amec Foster Wheeler (Amec) 2017 NI 43-101 Technical Report (Amec, 2017).

 

5.4 Past Production

 

Mechanized open pit mining at the Vazante Operation commenced in 1969. The initial mining operations exploited the supergene calamine mineralization which was formed by a mixture of hemimorphite (Zn4(Si2O7)(OH)2.H2O) and smithsonite (ZnCO3) that were derived from weathering of the primary willemite mineralization. Open pit mining operations of willemite mineralization were suspended in 2000, followed by the suspension of open pit production of calamine mineralization in 2008.

 

Development of the Vazante Operation underground mines began in 1983, with initial minor production of willemite mineralization taking place in 1984. The underground mines exploit the primary willemite mineralization (Zn2SiO4) along with minor to trace amounts of sphalerite. Production from the underground mines is ongoing. Between 1982 and 2019 a total of 230,489 m of level development has been completed in the underground mines (Figure 5-1).

 

 

 

Figure 5-1:      Underground Mine Development 1982 to 2019, Vazante and Extremo Norte Mines

 

From inception to 2019, a total of 38,695,229 t of ore have been processed from both the open pit and underground mines. Beginning in 2018, increasing quantities of tailings sourced from the Aroeira TSF have been included as part of the plant feed stock for reprocessing. As of December 31, 2020, a total of approximately 0.2 million tonnes (Mt) of tailings have been fed to the processing plant.

 

A summary of the open pit production history is provided in Table 5-2 and a summary of the underground mine production is presented in Table 5-3. The production history for the open pit and underground mines is summarized in Figure 5-2.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000
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Table 5-2:      Summary of Open Pit Mine Production

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Year     Calamine Production
(Ore tonnes)
    Willemite Production
(Ore tonnes)
 
  1969       6,000       2,700  
  1970       13,000       5,720  
  1971       24,000       10,512  
  1972       32,000       13,600  
  1973       48,000       21,120  
  1974       74,000       31,450  
  1975       73,000       31,390  
  1976       110,000       46,200  
  1977       121,000       50,215  
  1978       151,000       57,380  
  1979       232,000       69,600  
  1980       280,000       72,800  
  1981       316,000       -  
  1982       501,000       -  
  1983       584,000       -  
  1984       156,054       419,967  
  1985       116,157       384,293  
  1986       209,221       400,785  
  1987       182,146       315,635  
  1988       267,139       538,475  
  1989       247,350       500,553  
  1990       129,799       609,522  
  1991       173,268       550,354  
  1992       78,470       595,242  
  1993       279,727       629,893  
  1994       185,777       553,879  
  1995       137,538       376,879  
  1996       111,138       187,200  
  1997       205,322       296,322  
  1998       181,070       163,086  
  1999       188,601       85,499  
  2000       183,146       56,289  
  2001       210,211       -  
  2002       278,049       -  
  2003       495,754       -  
  2004       441,064       -  
  2005       500,949       -  
  2006       501,754       -  
  2007       366,582       -  
  2008       285,631       -  
  Total       8,676,917       7,077,280  

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000
Technical Report Summary - February 15, 2021

 

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Table 5-3:      Summary of Underground Mine Production

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Year     Plant Feed
(t)
    Plant Head Grade
(% Zn)
    Contained Metal
(t Zn)
 
  1984       657       -       -  
  1985       20,342       -       -  
  1986       4,621       -       -  
  1987       13,942       -       -  
  1988       5,965       -       -  
  1989       -       -       -  
  1990       2,050       -       -  
  1991       21,999       -       -  
  1992       42,174       -       -  
  1993       31,410       -       -  
  1994       115,797       -       -  
  1995       143,504       -       -  
  1996       226,996       -       -  
  1997       227,927       -       -  
  1998       309,426       -       -  
  1999       416,583       -       -  
  2000       441,902       14.58       64,429  
  2001       531,606       14.97       79,581  
  2002       590,500       15.14       89,402  
  2003       680,251       15.04       102,310  
  2004       708,385       15.10       106,966  
  2005       815,821       14.43       117,723  
  2006       868,726       15.67       136,129  
  2007       1,026,790       15.33       157,407  
  2008       986,447       14.61       114,210  
  2009       1,096,662       15.12       165,815  
  2010       1,301,527       15.37       173,940  
  2011       1,323,742       13.14       173,940  
  2012       1,401,281       10.80       151,338  
  2013       1,389,520       10.80       150,068  
  2014       1,389,574       11.25       156,327  
  2015       1,355,200       11.68       158,287  
  2016       1,298,545       11.93       154,960  
  2017       1,348,254       12.39       167,082  
  2018       1,360,761       11.89       161,799  
  2019       1,441,625       10.76       155,115  
  2020       1,622,927       10.43       169,271  
  Total       24,563,959       -       -  

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000
Technical Report Summary - February 15, 2021

 

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Source: Nexa, 2020

 

Figure 5-2:     Summary of Open Pit and Underground Mine Production

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000
Technical Report Summary - February 15, 2021

 

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6.0 Geological Setting, Mineralization, and Deposit

 

6.1 Regional Geology

 

The South American Platform is mainly composed of metamorphic and igneous complexes of Archean/Proterozoic age and makes up the continental interior of South America. The Platform consolidated during the Late Proterozoic to Early Paleozoic times in the course of the Brasiliano/Pan-African orogenic cycle during which the amalgamation of different continents and micro continents with the closure of several ocean basins led to the formation of the Supercontinent Gondwana. Archean and Proterozoic rocks are exposed in three major shield areas within the framework of Neoproterozoic fold belts (Guiana, Central Brazil, and Atlantic shields). The western continental margin of the South American Plate developed from at least Neoproterozoic to Early Paleozoic times and constitutes a convergent margin, along which eastward subduction of Pacific oceanic plates beneath the South American Plate takes place. Through this process, the Andean Chain, the highest non-collisional mountain range in the world, developed. The eastern margin of the South American Plate forms a more than 10,000 km long divergent margin, which has developed as a result of the separation of the South American Plate and the African Plate since the Mesozoic era through the opening of the South Atlantic and the break-up of Gondwana. The northern and southern margins of the South American Plate developed along transform faults in transcurrent tectonic regimes due to the collision of the South American Plate with the Caribbean and Scotia plates. The South American Plate reveals a long and complex geologic history (Engler, 2009). Figure 6-1 is a simplified geological map of Brazil.

 

The Project is underlain by Paleoproterozoic and Mesoproterozoic-aged (1.80 Ga to 1.55 Ga) lithologies belonging to the Río Negro-Juruena Province, one of six major geochronological provinces comprising the Amazonian Craton. The Río Negro-Juruena Province occupies a large portion of the western part of the Amazonian Craton (Figure 6-2) and includes volcano-sedimentary sequences, felsic plutonic-gneiss, and granitoids. Rift basins within the province are filled with continental platform molasse and marine sediments of Mesoproterozoic, Paleozoic, and Mesozoic age (Engler, 2009). It is a zone of complex granitization and migmatization. Regional metamorphism, in general, occurred in the upper amphibolite facies (Tassinari et al., 2010)

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000
Technical Report Summary - February 15, 2021

 

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Figure 6 1:      Regional Geology

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000
Technical Report Summary - February 15, 2021

 

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Figure 6-2:     Geological Map of the Amazonian Shield

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000
Technical Report Summary - February 15, 2021

 

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6.2 Local Geology

 

The Vazante Operation is situated within the Tocanitins Province (Almeida et. al., 1977), an orogenic system located between the São Francisco Craton, the Amazon Craton, and a potential covered third cratonic block located in the Paraná watershed. The province is bordered by three orogenic mountain ranges: the Paraguay and Araguaia Ranges that border the Amazon Craton, and the Brasilia range, which borders the São Francisco Craton. The regional geology is presented in Figure 6-3.

 

A geological map of the Vazante Operation area is presented in Figure 6-4. All known zinc mineralization in the Vazante Operation area is hosted by the Meso-Neoproterozoic aged Vazante Group. The generalized stratigraphy of the Vazante Group is presented in Figure 6-5.

 

The Vazante Formation was first proposed by Dardenne (1979) to designate a set of pelitic-carbonate units traditionally attributed to the Bambuí Group. The Vazante Formation was subdivided into three sections: basal, intermediate, and top. Later, Dardenne et. al. (1998) redefined the Vazante Formation as the Vazante Group which included the Retiro, Lagamar, Serra do Garrote, Serra do Poço Verde, Morro do Calcário, and Serra da Lapa Formations.

 

Zinc-lead deposits hosted in pelitic-carbonate rocks of the São Francisco Craton are considered to be genetically connected to regional compression that forced basinal brines out and upward along regional structures (Guimarães, 1962, Beurlen, 1974, Lyer et. al., 1992, and Lyer, 1984). Major zinc deposits hosted by Vazante Group units occur as two major types. The first being represented by the Vazante zinc silicate deposit, and the second by the Morro Agudo zinc sulphide deposit. These deposit types have distinct lithostratigraphic controls as well as significant difference in terms of hydrothermal (Vazante) and syn-diagenetic (Morro Agudo) origins. Geochronological information presented in Olivio et. al. (2018) suggests that the age of the Middle Pamplona Member (the host to the Vazante zinc-silicate mineralization) ranges from approximately 2.10 Ga to 1.82 Ga while the age of the Upper Pamplona Member (the host to the Morro Agudo zinc-sulphide deposit) is approximately 1,082 Ma +/- 14 Ma.

 

 

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Figure 6-3:     Regional Geological Map of the Brasilia Fold Belt

 

 

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Figure 6-4:     Local Geology of the Vazante Mine Area

 

 

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Figure 6-5:     Generalized Stratigraphic Column of the Vazante Area

 

 

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6.3 Property Geology

 

The geology of the Vazante Operation area consists of a sequence of pelitic carbonate rocks belonging to the Serra de Garrote and Serra do Poço Verde formations of the Vazante Group (Figure 6-6). The currently known mineralization has been traced along a strike length of approximately 10.5 km, extending from the southern end of the Vazante Mine to the northern limits of the Extremo Norte Mine.

 

6.3.1 Serra do Garrote Formation

 

The Serra do Garrote Formation consists of carbon rich phyllites containing ferruginous breccias and hematite blocks. The ferruginous breccias are attributed to surficial weathering processes while the hematite blocks are possibly due to hydrothermal fluid flows. The phyllitic rocks are carbon rich, black to dark gray when fresh, and quite homogenous in their appearance. Outcrops of these units are abundant in the Vazante Operation area, taking the form of flat outcrops in such locations as stream bottoms and in cliffs, road-cuts, and ravines.

 

In the field, these phyllites appear as laminated rocks occurring as alternating beds with different colours and particle sizes (Figure 6-7). The thickness of the bedding ranges from millimetre scale to centimetre scale. The sedimentary bedding (S0) is observed to typically occur parallel to subparallel to the cleavage (S1). These rock units are also affected by last phase kink-banding that is attributed to a regional deformation event (D1), and by locally developed crenulation cleavage.

 

The composition of the phyllite units consist primarily of sericite, chlorite, and quartz with minor amounts of detrital crystals of feldspar, tourmaline, and stilpnomelane. Iron hydroxide and oxide pseudomorphs after pyrite located interstitially to irregular sericite blades and quartz crystals.

 

 

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Figure 6-6:     Property Geology

 

 

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Source: Amec, 2017.

 

Figure 6-7:         Examples of Phyllites of the Serra Do Garrote Formation

 

6.3.2 Serra do Poço Verde Formation

 

In the Extremo Norte Mine area, the Serra do Poço Verde Formation is represented from base to top by the Lower Morro do Pinheiro, Upper Morro do Pinheiro, and Lower Pamplona members. The Lower and Upper Morro do Pinheiro members occur to the east of the Vazante Fault at the contact between the footwall and the hydrothermal dolomite breccia. The Lower Pamplona member occurs west of the Vazante Fault, at the contact between the cover and breccia.

 

6.3.2.1 Lower Morro do Pinheiro Member

 

Proposed by Dardenne (1978), the Lower Morro do Pinheiro Member occurs at the base of the dolomitic sequence of the Serra do Poço Verde Formation in the Extremo Norte Mine area. It consists of gray and sometimes pinkish coloured dolomites containing algal mat features. Occasional birds eye features are observed, consisting of lens shaped intergranular spaces filled with sedimentary material.

 

This Lower Morro do Pinheiro Member features dolomitic conglomerates (dolorudites) that are characterized by angular to subrounded clasts of different sizes, arranged in a limey mud (micritic) matrix. It consists almost exclusively of dolomite and some rare opaque crystals and quartz. The unit is locally silicified and can contain iron rich dolomite, quartz, and dolomite crenulations.

 

The almost monomineralic composition is probably related to diagenetic processes that favoured complete dolomitization. The presence of dissolution structures and cavity filling such as stromatictis (which consist of cavities filled by well developed crystals of dolomite with quartz at the middle) is considered to be related to the diagenetic dolomitization process. Much of the unit near the Extremo Norte Mine is interpreted to be a diagenetic collapse breccia (Figure 6-8).

 

6.3.2.2 Upper Morro do Pinheiro Member

 

The Upper Morro do Pinheiro Member was initially defined by Dardenne (1978). This member features thinly bedded dolomite, with clay sized to silt sized mineral grains and a massive to slightly laminated structure. This member displays only minor evidence of hydrothermal alteration and has maintained a light and/or dark gray colour. Primary structures including birds eyes and algal mats are preserved (Figure 6-9).

 

 

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Source: Amec, 2017.

 

Figure 6-8:         Intraclast Breccias with Subangular Clasts in Dolomite Matrix, with Stromatactis Filled with Dolomite

 

 

Source: Amec, 2017.

 

Figure 6-9:         Images of Gray, Massive Dolomite Containing Birds-Eyes (A), and Bird’s Eyes Structures (B)

 

The dolomite contains local intraclast breccia lenses with angular clasts of various sizes ranging from 0.2 cm to 10 cm that are surrounded by a dolomite matrix. Gray to greenish metapelite layers with average thicknesses of approximately two metres to three metres occur in the Upper Morro do Pinheiro Member. It is possible to clearly define two metamorphic foliations in the metapelites. One cleavage is a continuous cleavage that features a slaty cleavage while the second cleavage is discontinuous and often generates a crenulation of the early cleavage (Figure 6-10).

 

6.3.2.3 Lower Pamplona Member

 

The Lower Pamplona Member was defined by Dardenne (1978) and is located west of the Vazante Fault in a down dropped block.

 

The Lower Pamplona Member consists of a metadolomite that is pinkish in colour, fine grained, and marked by the presence of algal mats that define a sedimentary bedding (Figure 6-11). It contains several marly intervals that range in colour from purple to greenish. Two metamorphic foliations are recognized in the marls.

 

 

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The Lower Pamplona Member has been extensively altered by hydrothermal fluids that have commonly produced siderite and ankerite veinlets, and locally, some brecciation. The metadolomite is sometimes totally silicified.

 

 

Source: Amec, 2017.

 

Figure 6-10:          View of a Metapelite Featuring Two Metamorphic Foliations Oriented Oblique to Each Other

 

 

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Source: Amec. 2017.

 

Figure 6-11:         View of Pink-Coloured Dolomite with Algal Mats and Primary Bedding (A) and Containing Meta-Marl Intercalations (B)

 

6.3.2.4 Brecciated Dolomites (Hydrothermal Breccia)

 

Brecciated dolomites are exposed in a north-south oriented strip associated with the Vazante Fault. They cut the Extremo Norte Mine area where they thicken near the contact with the Serra de Garrote Formation and are characterized by intense strain (D3) that allowed the brecciated structure to develop (Figure 6-12).

 

The rock is generally pink to reddish in colour, and few primary structures or bedding features are preserved. The unit is highly veined by thick siderite, ankerite, and dolomite veins. Clasts are round to sub rounded in shape, suspected to be due to the partial assimilation that took place during the flow of the hydrothermal fluids. The clasts are chaotically disposed in a totally recrystallized dolomite matrix that has a comb structure.

 

 

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Source: Amec, 2017.

 

Figure 6-12:          Example of Dolomite Breccia with Intense Veinlet Development

 

6.4 Hydrothermal Alteration

 

Regionally, hydrothermal alteration is primarily controlled by brecciation and structures relating to brecciation. The most common alteration minerals are siderite, ankerite, quartz, and hematite, which can occur both as veins, and matrix infillings around breccia clasts. Gahnite was noted in some veinlets close to economic grade mineralization (Monteiro et. al., 1999).

 

Pervasive hematite alteration may cause a colour change in the dolostones from gray to pink. Silicification within the dolostones is also a common alteration signature (Slezak, 2012).

 

Hydrothermal alteration is well developed in and around the mineralized zones (Figure 6-13). The alteration minerals comprise pervasive ferroan dolomite, ankerite, siderite, and replacement silica that persist for up to 100 m to 150 m into the hanging wall and up to approximately 50 m into the footwall of the fault zone (Hitzman et. al., 2003). Within the Vazante Fault zone, silica-hematite veins cut ferroan dolomite, particularly along the upper and lower edges of the fault zone.

 

 

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Figure 6-13:     Typical Example of Alteration Style and Mineralogy

 

 

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6.5 Mineralization

 

The zinc-lead-silver mineralization at the Vazante Operation is hosted by the Vazante Shear Zone which has been traced by drilling and sampling along a strike length of approximately 12 km. The Vazante Shear Zone has a general strike of azimuth 50° and dips approximately 60° to the northwest at surface (Figure 6-14). The hanging wall lithologies of the Vazante Shear Zone are comprised of dolostone and sericitic phyllite, slates and marl units of the Serra do Poço Verde Formation while the footwall lithologies to the Vazante Shear Zone are dominated by dark grey dolostones of the Upper Morro do Pinheiro Member. Drilling information indicates that the dip of the zinc mineralized zone gradually decreases with depth in the southern portions of the structure.

 

The zinc mineralization at the Vazante and Extremo Norte mines is composed largely of hypogene zones that are composed mainly of willemite (Zn2SiO4) veins, veinlets, and stockworks that are hosted by sphalerite rich carbonate. The mineralization typically contains willemite (50% to 70%), dolomite (10% to 30%), siderite (10% to 20%), quartz (10% to 15%), hematite (5% to 10%), zinc rich chlorite (5% to 10%), barite (<5%), franklinite (<5%), and zincite (<5%), with subordinate concentrations of magnetite and apatite (Monteiro et. al., 2006). Lead and silver are also recovered from the hypogene mineralization produced from the Vazante Operation. While no detailed studies regarding the specific lead and silver bearing minerals have been carried out on samples of the hypogene mineralization, several detailed mineralogical studies have been conducted using concentrate samples. SLR notes that the majority of the lead mineralization in the concentrates has been found to be related to galena (PbS), with lesser amounts of lead being contained in cerussite (Pb(CO3)). Mineralogical studies have indicated that the silver values are contained in the minerals acanthite (Ag2S) and jalpaite (Ag2CuS2).

 

Supergene zones of zinc rich mineralization have been developed in the near surface portions of the hypogene mineralized zones. These supergene zones are referred to as the calamine zones at the Vazante Operation. The calamine mineralization is composed principally of smithsonite (ZnCO3) that includes subordinate amounts of hemimorphite (Zn4(Si2O7)(OH)2.H2O) and quartz. The calamine mineralized zones were derived from weathering of the primary willemite mineralization.

 

 

 

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Figure 6-14:     View of the Geology, Alteration, and Mineralization

 

 

 

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6.6 Deposit Descriptions

 

6.6.1 Vazante

 

The zinc silicate mineralization of the Vazante deposit is hosted in a tectonic hydrothermal breccia zone that is found near the contact between the Lower Pamplona and the Upper Morro do Pinheiro Members of the Vazante Group. Metamorphosed dikes are tectonically imbricated with the carbonates and hydrothermal breccias in the main orebody.

 

The Vazante portion of the orebody, which is approximately seven kilometres in length, has a variable thickness, and has been traced by drilling to a depth of approximately 800 m below surface. Willemite can form as pods, veinlets, and metre wide veins within the hydrothermal breccia and is locally controlled by antithetic faults in the deposit. The willemite composition, according to electron micro-probe (EMP) studies conducted by Monteiro et. al. (2006), has been shown to contain minor amounts of FeO (up to 0.3 wt%) and Ca (up to 0.13 wt %).

 

Willemitic mineralization is tectonically imbricated with small sulphide orebodies, metabasites, and brecciated metadolomites. The sulphide orebodies are offset by normal and reverse faults and are cut by late hydrothermal veins. This can cause a complex relationship between orebodies and host rocks. The sulphide bodies consist of iron poor sphalerite with round inclusions of galena, and occasional inclusions of hematite, quartz, and dolomite. The relationship between sphalerite and willemite is not well understood. They may have co-precipitated from the same solution (Monteiro et. al., 1999, Hitzman et. al., 2003), or the willemite may be an alteration or metamorphic product after sphalerite (Appold and Monteiro, 2009). Typical cross sections through the Lumiadeira and Sucuri areas of the Vazante Mine are presented in Figure 6-15 and Figure 6-16, respectively.

 

 

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Figure 6-15:     Cross Section of the Lumiadeira Area, Vazante Mine

 

 

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Figure 6-16:     Cross Section of the Sucuri Area, Vazante Mine

 

 

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6.6.2 Extremo Norte

 

The Extremo Norte mineralization is associated with the Vazante Shear Zone, and is primarily hosted in the Lower Pamplona Member, or along the contact between the Lower Pamplona and Upper Morro do Pinheiro Members.

 

The mineralization consists of willemite (in variable quantities, but can reach up to 40% in abundance), specular hematite (1% to 50%), and minor franklinite (ZnFe2O4). The mineralized zones occur as a primary gently undulating, northwest dipping tabular sheet that has been traced by drilling along a strike length of approximately four kilometres and to a depth of approximately 600 m from surface.

 

The mineralization at the Vazante Mine is observed to generally contain more sulphide minerals associated with the willemite, and observations suggest that it has experienced a higher degree of ductile deformation than is observed at the Extremo Norte deposit. Metamorphosed and hydrothermally altered basic dikes are tectonically imbricated with the carbonates and the hydrothermal breccias in the Vazante Mine (Babinski et. al., 2005), but these have not been observed at the Extremo Norte deposit (McGladrey, 2014).

 

A paragenetic history of the Extremo Norte deposit has been proposed by Slezak et. al. (2013) and is presented in Figure 6-17 and Figure 6-18.

 

  

 

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Figure 6-17:     Proposed Paragenetic History of the Extremo Norte Deposit

 

 

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Figure 6-18:     Proposed Genetic Model for the Extremo Norte Deposit

 

 

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6.6.3 Calamine

 

The majority of the existing calamine mineralized zones are located along the Extremo Norte portion of the Lumiadeira-Sucuri-Extremo Norte mineralized trend. Several minor occurrences of calamine are located along the northeastern sections of the Sucuri trend of the Vazante Mine. The calamine mineralized zones consist of fully weathered supergene material that is derived from the primary willemite zinc mineralization and its enclosing host rock units (Figure 6-19 and Figure 6-20).

 

 

Source: Nexa

 

Figure 6-19:     View of In-Situ Calamine Mineralization

 

 

 

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Source: Nexa

 

Figure 6-20:      Example of Calamine Mineralization in Drill Core

 

 

 

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6.7 Deposit Types

 

The zinc deposit found at the Vazante Operation is the largest known non-sulphide zinc deposits in the world and is the type example for this class of mineral deposit. The Vazante Operation mineralization is composed primarily of hypogene zinc silicate minerals dominate in abundance by willemite. The primary hypogene willemite mineralization has been subjected to supergene weathering processes to produce secondary zinc mineralization, referred to as the calamine mineralization, which is composed of smithsonite (ZnCO3) and hemimorphite (Zn4Si2O7(OH)2).

 

Non-sulphide hypogene zinc deposits are known to occur either as stratiform deposits, or structurally controlled deposits. The mineralization at the Vazante Operation is an example of a structurally controlled deposit. Key features of structurally controlled deposits are:

 

· They occur in Neoproterozoic to Cambrian aged sedimentary basins that have been metamorphosed to at least sub-greenschist facies.

 

· They are hosted in carbonate rocks associated with major structures, such as district-scale faults and folds.

 

· They are associated with brecciation, which may be the result of karstification, or the result of tectonism and hydrothermal fluid flow.

 

· The dominant economic zinc mineral is willemite. Additional minerals may include zinc oxides such as zincite, franklinite, or zinc carbonates such as smithsonite.

 

· The alteration minerals can include ferroan dolomite, hematite, and quartz.

 

The Vazante Operation mineralization is linked to the development of the Vazante Shear Zone, which has been interpreted to be a transpressional transcurrent fault that later reactivated as a normal fault (Monteiro et. al, 2007, Pinho, 1990).

 

The hypogene mineralization has two strong controls, lithostratigraphic and structural. The Vazante Operation deposit is clearly confined to a clay-dolomite interval near the contact between the Lower Pamplona Member and the Lower Morro do Pinheiro Member. Mineralization is restricted to the brecciated area in the fault zone that has had a long history of reactivation (Monteiro, 2002). This hypogene mineralization is interpreted to result from deposition of metals from hydrothermal fluids that have moved through the Vazante Shear Zone.

 

The morphology of the Vazante Operation deposit consists of veins and anastomosing podiform bodies that are fault bounded. The geochemical controls on the deposition of the mineralization are not well understood and the source of the metals is not known. The deposit genesis is thus in debate, as it may have originally represented a sulphide deposit that was subsequently silicified, or it may have consisted of primary zinc silicate mineralization that was later re-concentrated into the Vazante Shear Zone.

 

Work by Monteiro et. al, (1999, 2006, and 2007) suggest that the willemite can form by reacting sphalerite and quartz through the reaction:

 

2ZnS + 2SiO2 + 2O2 = 2ZnSiO4 + S2 .

 

This reaction would presumably occur during a low-grade metamorphic event.

 

Brugger et. al. (2003) investigated the origin of these deposits and suggested that the willemite could form by direct precipitation from hydrothermal fluids under high pH and high oxygen fugacity conditions.

 

Furthermore, Hitzman et. al. (2003) concluded that the fluids responsible for transporting zinc to the Vazante Operation type zinc deposits appear to be geochemically similar to solutions produced in many continental sedimentary basins. As non-sulphide zinc deposits appear to form from the mixing of highly oxidized, sulphur poor solutions with zinc bearing solutions, they could be found in the same districts as sphalerite-rich Mississippi Valley type or Irish type deposits formed by fluid mixing. Such appears to be the case in the Bambuí Group in Brazil.

 

 

 

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The Irish type Morro Agudo zinc-lead deposit, located approximately 100 km north of the Vazante Operation, occurs in rocks that are stratigraphically above the level of the mineralization at Vazante. Morro Agudo, like other Irish type deposits (Hitzman and Beaty, 1996), formed by the mixing of a metal rich, sulphur poor, reduced hydrothermal fluid with a sulphur rich fluid. Similarly, the Vazante Operation deposit may have formed through the mixing of a similar metal rich, reduced, hydrothermal fluid with a highly oxidized, sulphur poor fluid (Hitzman et. al., 2003).

 

 

 

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7.0 Exploration

 

7.1 Exploration

 

7.1.1 Introduction

 

Zinc was first discovered at the Vazante Operation in 1951 when areas of gossan and calamine mineralization were discovered in surface outcrops. Since 1951, exploration has largely consisted of geological mapping and geophysical surveying, with minor amounts of geochemical sampling programs being carried out to locate outcropping mineralized zones. In the Vazante Operation area, exploration programs (including drilling) have strategically been carried out in support of extensions of mining operations, including the possibility of deepening of the mine infrastructure.

 

While geochemical surveys are useful for locating those areas of outcropping mineralization, much of the mineralized zones at the Vazante Operation extend to depth and so limiting the effectiveness of geochemical surveys.

 

Geophysical surveys are useful for detecting mineralized zones to shallow depths and are also useful to assist in defining the location of controlling structures. As the surface and near-surface potential has been evaluated by these methods, increasingly diamond drilling programs are becoming the primary exploration tool for locating additional mineralized zones at depth.

 

7.1.2 Grid Datums and Topography Surveys

 

Two grid systems are used in the Vazante Operation area. For regional exploration programs, all location information is collected using the UTM SIRGAS 2000 Zone 23S datum. For exploration programs located in the vicinity of the mine areas, the location information is collected using the UTM Córrego Alegre Zone 23S datum.

 

The regional topographic surface is created from data collected from the Shuttle Radar Topography Mission (SRTM), an international research effort in February 2000 that obtained digital elevation models on a near global scale from latitudes of 56°S to 60°N. Contour lines were created from this information at five metre intervals using the GEOSOFT software package.

 

7.1.3 Geological Mapping Programs

 

Geological mapping programs have been conducted by a number of the prior owners of the mineral tenements. These include US Steel (1969), Rio Doce Geologia e Mineração S/A (1970’s), Serviços Geológico Do Brasil (1986, 2013, and 2015), and Votorantim, now Nexa, (2004 to date).

 

The scales of the geological mapping programs have ranged from regional mapping scales of 1:100,000, 1:75,000, and 1:50:000 in which the basic lithological framework was established to more local scale mapping programs at scales of 1:10,000 as exploration activities identified target areas that were believed to warrant collection of additional geological information at a more detailed level. Throughout these various mapping programs, information such as the lithology types, location of gossan and sulphide occurrences, alteration zones, and the location of faults and structural data were collected. This information was then used as guides for more detailed exploration activities.

 

 

 

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7.1.4 Geochemical Sampling Programs

 

Geochemical exploration activities have included the collection of 1,417 rock chip samples (Figure 7-1), 133 pan concentrate samples (Figure 7-2), 633 stream sediment samples (Figure 7-3), and 4,080 soil samples (Figure 7-4).

 

The rock chip samples were collected mostly from selected outcrops of the Morro do Calcário Formation, while stream sediment samples were collected where favourable sites were present. Soil samples were collected primarily over areas that were considered to be underlain by the Morro do Calcário Formation. The results from all of these surveys were used to develop exploration drill targets.

 

 

 

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Figure 7-1:     Location Plan, Rock Chip Samples

 

 

 

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Figure 7-2:     Location Plan, Panning Concentrate Samples

 

 

 

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Figure 7-3:     Location Plan, Stream Sediment Samples

 

 

 

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Figure 7-4:     Location Plan, Soil Samples

  

 

 

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7.1.5 Geophysical Surveys

 

7.1.5.1 Airborne Surveys

 

An airborne magnetic survey was carried out in 2000 to 2001 by Lasa Engenharia e Prospecções S.A, a geophysical contractor on behalf of Companhia Mineradora de Minas Gerais (COMIG). The survey used a fixed wing Islander BN2-A aircraft equipped with a caesium vapour, Scintrex CS-3 model, with a 10 Hz frequency and a sampling interval of six metres. Control lines were spaced at intervals of 2,600 m, with individual flight lines at 250 m intervals. The average flight height was approximately 100 m. In total, the magnetic survey provided approximately 85,155 line-km of data.

 

A second airborne survey that collected magnetic and gamma ray spectrometry information was carried out in the region in 2010 by Lasa on behalf of Votorantim. This survey covered an area of approximately 346.2 km2. The aircraft used was a Caravan C208 (PR-FAK) with flight lines approximately 150 m apart and control lines approximately 1,500 m apart. The average flight height was approximately 100 m. The aircraft was equipped with a Scintrex cesium vapor sensor, model CS-3, with a resolution of 0.001 nT. The gamma ray spectrometry information was collected using a Picodas PGAM 1000 multichannel gamma-spectrometric system, with thallium-activated sodium iodide (NaI) detecting crystals, with a sampling frequency of 1Hz and 60m sample interval.

 

Gravity measurements totalling 2,632 line-km of data were also collected during this survey using the FALCONTM AGG system.

 

An excerpt of the regional magnetic information for the Vazante Mine area is provided in Figure 7-5 , while gamma spectroscopy information is provided in Figure 7-6. The purpose of the magnetic surveys were to assist in the delineation of fault structures and lineaments that could have played a role in the localization of the mineralizing fluids. The gravity data was used in an attempt to differentiate areas of zinc mineralization, as there could be a marked difference between the host rocks and zones of sphalerite/willemite mineralization.

 

 

 

Nexa Resources S.A.│Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000
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Figure 7-5:      Regional Magnetic Data for the Vazante Mine Area

 

 

 

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Figure 7-6:     Regional Gamma Spectroscopy Data for the Vazante Mine Area

 

 

 

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7.1.5.2 Ground Based Surveys

 

Nexa has executed a number of ground based geophysical surveys starting in 2009 as summarized in Table 7-1.

 

 

 

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Table 7-1:      Summary of Ground Based Geophysical Surveys

Nexa Resources S.A. – Vazante Polymetallic Operations

  

    Geophysical   Airborne (A) /   Public (Pb) /                                                                                
Prospect    Method   Terrestrial (T)   Private (Pv)   Company   2009       2010       2011       2012       2013       2014       2015       2016       2017       2018       2019  
                    line-kilometer  
Cabeluda   Conventional IP   T   Pv   Geomag   -       -       -       -       3.60       -       -       -       -       -       -  
Carrapato   Conventional IP   T   Pv   Geomag   -       -       -       -       -       -       -       -       -       2.35       -  
Extremo Norte   Conventional IP   T   Pv   Geomag   -       -       -       -       -       -       -       1.30       -       -       -  
Ferradura   Conventional IP   T   Pv   Geomag   -       -       -       -       -       -       -       -       -       4.45       -  
Lajes   Conventional IP   T   Pv   Geomag   -       -       -       -       -       -       -       -       3.70       -       -  
Lumiadeira   Conventional IP   T   Pv   Geomag   -       -       -       -       -       -       -       -       11.30       -       -  
Salobo   Conventional IP   T   Pv   Geomag   -       -       -       -       -       -       -       -       11.45       -       -  
Calamina   Electrical Resistivity
Tomography
  T   Pv   Geodecon   -       -       -       -       -       -       -       -       -       15.20       -  
Calamina   Electrical Resistivity
Tomography
  T   Pv   Geodecon   -       -       -       -       -       -       -       -       -       -       6.00  
Lumiadeira   Electrical Resistivity
Tomography
  T   Pv   Geodecon   -       -       -       -       -       -       -       -       -       -       20.67  
Várzea Poço Verde   Electrical Resistivity
Tomography
  T   Pv   Geomag   -       -       -       -       -       -       -       -       6.40       -       -  
Sungem   Fullwave IP   T   Pv   Geomag   -       -       -       -       -       -       -       -       -       -       4.05  
Vazante Sul   Fullwave IP   T   Pv   Geomag   -       -       -       -       -       -       -       -       -       -       20.88  
Mina   Gravity   T   Pv   Prospecgeo   10.41       -       -       -       -       -       -       -       -       -       -  
Água Doce   Magnetometry   T   Pv   Nexa   14.30       -       -       -       -       -       -       -       -       -       -  
Alcalina Vz Sul   Magnetometry   T   Pv   Nexa   -       -       -       -       10.70       -       -       -       -       -       -  
Masa   Magnetometry   T   Pv   Nexa   24.90       -       -       -       -       -       -       -       -       -       -  

  

 

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Prospect   Geophysical
Method
  Airborne (A) /
Terrestrial (T)
  Public (Pb) /
Private (Pv)
  Company   2009       2010       2011       2012       2013       2014       2015       2016       2017       2018       2019  
                line-kilometer  
Mata 1 / 2   Magnetometry   T   Pv   Nexa   90.90       -       -       -       -       -       -       -       -       -       -  
Mata Preta   Magnetometry   T   Pv   Nexa   -       -       -       -       7.04       -       -       -       -       -       -  
Mina   Magnetometry   T   Pv   Nexa   144.60       -       -       -       -       -       -       -       -       -       -  
Olho D'Água   Magnetometry   T   Pv   Nexa   -       103.04       -       -       -       -       -       -       -       -       -  
Pasto   Magnetometry   T   Pv   Nexa   -       20.35       -       -       -       -       -       -       -       -       -  
Salobo   Magnetometry   T   Pv   Nexa   136.60       -       -       -       -       -       -       -       -       -       -  
Soledade   Magnetometry   T   Pv   Nexa   34.35       -       -       -       -       -       -       -       -       -       -  
Sungem   Magnetometry   T   Pv   Nexa   36.12       -       -       -       -       -       -       -       -       -       -  
Varginha   Magnetometry   T   Pv   Nexa   109.70       -       -       -       -       -       -       -       -       -       -  
Lajes   Magnetometry   T   Pv   Nexa   -       -       -       -       -       -       -       18.00       -       -       -  
Varginha   Resistivity   T   Pv   Intergeo   -       -       -       -       -       14.40       -       -       -       -       -  

 

 

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7.1.6 Exploration Potential

 

The Nexa geological team has continued to conduct exploration activities in the immediate environs of the Vazante Mine as well as in the neighbouring regions. The regional exploration programs have discovered several occurrences of zinc mineralization including Vazante Norte, Carrapato, Vazante Sul, and Sugem (Figure 7-7).

 

7.1.6.1 Regional Targets

 

7.1.6.1.1 Vazante Sul Target

 

The Vazante Sul Target is located south of the town of Vazante. Integration of all available data from historical drilling campaigns, and three element analyses of soil and rock samples has allowed a reinterpretation of the conceptual model for the Vazante Sul area and opened a potential mineralized trend approximately 15 km in length. This was followed by selected soil sampling and multi-elemental analyses, geological mapping at a scale of 1:10,000, and further three-dimensional modelling. The conceptual exploration model is based on the continuity of the Vazante Fault to the south of the town of Vazante. Observations made at the Vazante Mine suggest that the mineralization is deformed by northwest trending folds as well as by low angle faults. These observations have led to the view that the same should occur for a possible non-sulfide mineralization on the Vazante Sul trend. Historically the region was mapped as “undifferentiated dolomite” due the lack of outcrops and the thick soil cover, but re-evaluation of historical drill holes as well as detailed geological mapping found the presence of the pink dolomite that is recognized at the Vazante Mine as the main host rock for mineralization.

 

IP surveys (total 20.88 km in length) were carried out along five profiles on the Vazante Sul trend to search for stratigraphic discontinuities and areas of high resistivity, as intense silicification of the breccias that hosts the Vazante ore are known to increase resistivity.

 

Three drill holes were proposed in areas of favorable geological setting, discrete soil anomalies (due the thick allochthonous soil cover), and geophysical high resistivity. Two of the drill holes were in progress and were expected to be completed during December 2020.

 

 

 
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Figure 7-7:            Zinc Occurrences of the Vazante Mine Area

 

 

 
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7.1.6.1.2 Sungem

 

The Sungem Target is located approximately 10 km from the village of Coromandel and 110 km southwest of the town of Vazante. Historical drill cores collected by the company Mearim who were prospecting for diamonds intercepted zinc-lead mineralization hosted in carbonatic rocks.

 

In 2020, two IP profiles and three drill holes were executed by Nexa to identify the system. Zinc sulphide occurrences were intercepted and a further drilling campaign is proposed to extend zinc potential towards the northeast (Figure 7-8).

 

 

 

Source: Nexa

 

Figure 7-8:          Hydrothermal Breccia and Zinc Sulphide Mineralization from the Sungem Target

 

7.1.6.1.3 Mata Preta Prospect

 

The Mata Preta prospect is located south of the town of Vazante, near the contact between the Serra Do Garrote black shales and the grey dolomites of the Morro do Pinheiro Formation. Outcrops in the area show potential for sulphide mineralization controlled by structures (Figure 7-9). Grab samples collected containing sphalerite have returned up to 15,000 ppm Zn and 661 ppm Pb.

 

 

 
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Source: Nexa

 

Figure 7-9:        Vein-Hosts Sphalerite in Veins Associated with Hydrothermal Dolomite and Quartz, Mata Preta Prospect

 

 

 
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A geophysical IP profile completed on the Vazante Sul area to the southwest indicated a potential northeast trend of five kilometres towards the Mata Preta target (Figure 7-10). Association of high resistivity and high chargeability can indicate presence of sulphides.

 

Multi-elemental soil samples also correlate with the northeast trend showing anomalies in several elements such as Zn, Pb, Cu, As, Be, Ag, Fe, V, Cd and Ba (Figure 7-11).

 

 

 

Source: Nexa

 

Figure 7-10:                Location of the Mata Preta Prospect and Potential Mineralized Corridor

 

 

 
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Source: Nexa

 

Figure 7-11:                 Three Dimensional Model of the Mata Preta Prospect Showing Multi Element Geochemical Anomalies

 

7.1.6.1.4 Carrapato Trend

 

The Carrapato trend is located northwest of the town of Vazante. Integration and re-interpretation of historical data indicated two potential trends observed on the three elements soil anomalies with zinc and lead values higher than 500 ppm, as well as in rock samples with up to 10.8% Zn (Figure 7-12). The trend is considered to have potential for containing sulphide and non-sulphide mineralization.

 

Geological mapping carried out by Nexa in 2020 has identified three areas that are considered to have potential of hosting zinc mineralization (Figure 7-13).

 

 

 
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Figure 7-12:                 Compilation of Historical Results, Carrapato Trend

 

 

 

Source: Nexa

 

Figure 7-13:                 Exploration Potential of the Carrapato Trend

 

 

 
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7.2 Drilling

 

7.2.1 Introduction

 

While the majority of drilling activities at the Vazante Operation are focussed in support of mining operations, a small number of exploration drill holes have been completed throughout the region to evaluate selected targets for their potential of hosting potentially economic concentrations of zinc mineralization. As of 2019, the regional core drilling programs have completed a total of 115 drill holes totalling 35,548.2 m in length (Figure 7-14, Table 7-2).

 

The regional exploration drill holes are drilled exclusively from surface based locations while the drill holes completed in support of the mining operations can be completed either from underground stations or from surface based locations. A small number of surface based drill holes were completed in the area of the open pit mines to evaluate the presence, distribution, and grade of areas of calamine mineralization. As well, a small number of “Direct Push” drill holes were completed in the Aroeira and Old Dam (Antiga) TSFs to provide information regarding the depths and grades of the accumulated tailings. Additional drilling was carried out in the area of the existing open pit mines to evaluate the extent and distribution of the calamine mineralization in those areas (Table 7-3,Figure 7-15). A summary of annual drilling completed at the Vazante Operation is presented in Table 7-4.

 

 

 
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Figure 7-14:             Location of Regional Exploration Drill Holes

 

 

 
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Table 7-2:             Summary of Regional Exploration Drilling

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Year   Drilling Type   Number of Holes
Completed
  Metres Completed
(m)
1976       2   283.9
1977       4   889.7
1982       2   623.5
1983       2   695.9
1984       8   1,201.6
1985       4   505.1
1986       1   485.4
1987       2   430.8
1990       1   254.8
1997       1   613.8
1998       1   217.1
1999       2   213.7
2006   Core   2   760.3
2007       1   244.4
2010       5   1,273.6
2011       5   1,285.9
2012       3   926.1
2013       2   715.7
2014       8   2,457.6
2015       7   4,147.3
2016       18   7,387.5
2017       17   4,632.6
2018       8   2,769.1
2019       3   1,011.2
Undated       6   1,521.6
Subtotal       115   35,548.2
2006   Auger   70   691.3
Total       185   36,239.5

 

 

 

Nexa Resources S.A.│Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000
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Table 7-3:             Summary of the Open Pit, Underground, and Tailings Sample Drill Hole and Sampling Data as at April 30, 2020

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Area   Type   No. of
Samples
  Total Length
(m)
Vazante (Lumiadeira & Sucuri)   Drill Core   6,186   1,036,581.7
             
    Chip/Channel Samples   1,089   5,972.7
             
Extremo Norte   Drill Core   1,399   345,495.7
             
    Chip/Channel Samples   199   1,147.5
             
Calamine Targets   Drill Core (Triple Tube)   415   39,569
             
Aroeira/Antiga TSFs   “Direct Push”   114   1,611.0

 

 

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Figure 7-15:           Location of Drill Holes and Channel Samples, Vazante and Extremo Norte Deposits

 

 

  

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Table 7-4:            Summary of Extension Drilling Completed by Year

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Year   No. of
Holes
  Length
(m)
2002   288   99,518.2
2003   10   3,956.7
2004   164   36,454.4
2005   479   117,252.2
2006   468   103,883.4
2007   274   45,510.1
2008   262   58,084.7
2009   345   55,788.6
2010   1,168   187,418.7
2011   1,245   115,622.8
2012   277   28,172.4
2013   578   85,895.3
2014   440   77,007.6
2015   395   67,094.0
2016   409   80,303.1
2017   170   25,046.4
2018   177   24,315.1
2019   126   24,437.6
Total   7,275   1,235,761.3

 

7.2.2 Drilling Methods

 

7.2.2.1 Drill Core

 

Drilling operations are performed by company personnel according to Standard Operating Procedures (SOPs) developed by Nexa staff (SOP numbers PO-VZ-GST-SON-005-PT and PO-VZ-GST-SOS- 003-PT). The Vazante Operation is certified by the Brazilian Standards Institute (BSI) for ISO9001 and ISO14001 standards (certificates FM504361 and EMS86481, respectively).

 

Drilling of the surface based core holes at the Vazante and Extremo Norte mines has been completed with a number of different drill machines, the types of which are not recorded.

 

The current drilling fleet consists of two surface drills, an Atlas drill model CS14 and Boart Longyear drill model LF90-D. The underground fleet includes five Boart Longyear model LM 75 drill rigs, and two Atlas U6 MCR model drill rigs.

 

 

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Surface drilling commences with a diameter that is HQ (96 mm) or larger to better accommodate difficult surface drilling. When the rock mass improves, drill holes are reduced to NQ (75 mm) diameter. In many instances, drilling conditions dictate that the hole diameter be reduced further, to BQ (36 mm).

 

Geological conditions for underground drilling are typically much better than surface conditions, as the drill holes start in fresh rock and thus, they typically employ BQ diameter tools throughout.

 

Drill hole collar locations of underground based drill holes and surface based exploration core holes are surveyed using either a total station or survey grade Global Positioning System (GPS) survey unit in the UTM coordinate system according to the Córrego Alegre 23S datum. The drill hole collars for the surface based and underground based drill holes for the Extremo Norte and Vazante deposits are slightly modified so as to comply with the grid coordinate system employed by the mining operations. The correction factors to translate from the UTM to the mine grid system are to subtract 300,000 from the UTM eastings and 8,000,000 from the UTM northings. No rotation corrections are applied.

 

The collar azimuth and initial dip of the diamond drill rods are measured using the same survey equipment. Downhole survey deviation measurements were collected in core holes by Nexa utilizing a Tropari deviation measuring instrument until 2005, while, a Reflex Maxibor I deviation measuring unit was used to measure the downhole deviations from 2002 to 2008. Post 2008, all downhole deviation measurements are collected using either a Reflex Maxibor II unit or a Reflex Gyro unit. These surveys are generally undertaken every 100 m as the hole progresses to monitor drilling deviation. Reflex survey data is collected at three metre intervals after the drill holes are completed. All downhole deviation measurements are collected according to the following SOPs:

 

· PO-VZ-GST-SON-001-PT

 

· PO-VZ-GST-SOS-005-PT

 

· PO-VZ-GST-GEO-017-PT

 

Drill core is placed into wooden boxes and then taken to a secure core logging and sampling facility located on the Vazante Operation property (Figure 7-16). Geology staff check and validate the survey data before entering the information into the main drill hole database.

 

 

 

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Figure 7-16:            View of Vazante Core Logging Facilities

 

7.2.2.2 Tailings Samples

 

Process tailings from the flotation circuit have been placed into three TSFs over the Vazante Operation’s operating history (Figure 7-17). The Antiga and MASA facilities have been closed, while the Aroeira TSF remains active. Drilling programs have been carried out on the Aroeira and Antiga TSFs in which samples of the tailings column were collected on a regularly spaced grid system for assaying and metallurgical testing purposes. The drilling and sampling programs were carried out by Nexa personnel using light weight, track mounted drilling equipment that collected complete cores by means of direct pushing of the drilling steel into the unconsolidated tailings (Figure 7-18). The drill holes were continued to refusal, at which point the drill hole was considered to have encountered the base of the tailings column. All drill holes were vertical (i.e. with dips of -90°) and the drill hole locations were determined by detailed survey using the UTM Córrego Alegre 23S datum. In contrast with the exploration and underground based core holes, no correction factors were applied to the collar locations of the tailings sampling holes, and the collars are plotted according to the UTM grid system rather than the mine grid system. A total of 79 holes were completed on the Antiga TSF for a total length of 1,023.7 m, and a total of 34 drill holes were completed on the Aroeira TSF for a total length of approximately 587.4 m (Figure 7-19).

 

The cored material collected from these drill holes was placed into plastic sleeves and transported to the core logging facility located at the Vazante Operation for processing.

 

 

 

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Source: Nexa

 

Figure 7-17:            View of the Vazante Operation Tailings Storage Facilities

 

 

 

Source: Nexa

 

Figure 7-18:           View of the Tailings Sampling Drilling Equipment

 

 

 

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Figure 7-19:          Collar Locations for the Antiga and Aroeira Tailings Drill Holes

  

 

 

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7.2.2.3 Calamine Drilling

 

Drilling programs were carried out in the area of the open pit mines whose objective was to collect lithology and grade information for the calamine mineralization in those areas where the existing drill holes were judged to be too widely spaced for use in the preparation of Mineral Resource estimates. The drilling programs were completed by drilling contractor Willemita Drillings using conventional wireline drilling equipment and by contractor Geosedna using rotopercussive drilling equipment. A triple tube core barrel (HQ sized) was applied to the drill string so as to collect the most complete samples possible of the fractured and porous material. The drilling procedures followed the normal procedures used to complete surface based drill holes as described previously. Once drilling was completed, the final locations of the collars were determined using survey grade GPS surveying equipment using the UTM Córrego Alegre 23S datum. No corrections were applied to the collar locations to align them with the mine grid.

 

SLR recommends that the coordinates for all of the calamine related drill holes be converted into the local mine grid coordinates so that the results from all Mineral Resource estimation activities can then be integrated with any underground mining activities that have been or are planned to be carried out in this area.

 

7.2.3 Logging Procedures

 

The description of the lithologies, alteration and mineralization observed in the drill cores as well as the sampling procedures are carried out by the site geologists according to the following SOPs that have been prepared by Nexa staff:

 

· PG-EXP-GTO-001-PT for quality assurance/quality control (QA/QC) (Duplicate)

 

· PG-EXP-GTO-002-PT for QA/QC (Certified Standard)

 

· PG-EXP-GTO-003-PT for QA/QC (External Check)

 

· PO-VZ-GST-GEO-004-PT for geological logging

 

· PO-VZ-GST-GEO-005-PT for core sampling

 

· PO-VZ-GST-GEO-006-PT for core shed operations

 

The core boxes are checked by the drilling support team, who review core size and recovery data, in addition to verifying the location of core blocks. If irregularities are discovered, they are resolved before the core is released to the core shack. All core is photographed, with drill holes then transferred to the core workbench where the core is described by a team of geologists and technicians. The principal items logged include lithology, alteration type and intensity, mineralization style and estimated abundance, colour, texture, weathering, structure, and fracture density.

 

Geotechnical and hydrogeological descriptions are also completed and stored in the geological database.

 

Core is marked up to show sample intervals selected for assaying and the locations of control samples. The sample intervals selected for assaying are adjusted to conform to the local lithological, alteration, or mineralization features observed in the drill core. Once the description of the core is complete, the boxes to be sampled are identified and the remaining boxes are stored. Typical examples of the mineralization encountered in the Extremo Norte, Vazante, Aroeira TSF, and calamine zones are presented in Figure 7-20 to Figure 7-23, inclusive.

 

 

 

Nexa Resources S.A.│Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000
Technical Report Summary - February 15, 2021

 

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Figure 7-20:          Representative Cross Section of the Extremo Norte Deposit

 

 

 

Nexa Resources S.A.│Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000
Technical Report Summary - February 15, 2021

 

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Figure 7-21:         Representative Cross Section of the Vazante Deposit

 

 

  

Nexa Resources S.A.│Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000
Technical Report Summary - February 15, 2021

 

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Figure 7-22:         Representative Cross Section of the Aroeira Tailings Sampling Program

  

 

 

Nexa Resources S.A.│Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000
Technical Report Summary - February 15, 2021

 

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Figure 7-23:         Representative Cross Section of the Calamine Mineralization

 

 

 

Nexa Resources S.A.│Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000
Technical Report Summary - February 15, 2021

 

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Considering the long production history of the Vazante Operation, the amount of drill hole data is far too extensive to provide a comprehensive summary of the significant mineralized intersections that have been encountered in the drill holes. The selected examples provided in Table 7-5 present typical examples of the nature of the zinc mineralization that has been encountered in the Extremo Norte deposit and the Lumiadeira and Sucuri portions of the Vazante Mine. SLR notes that the examples presented in Table 7-5 are drawn from the drill holes presented in Figure 7-20 and Figure 7-21.

 

Examples of significant intersections returned from the Aroeira TSF drilling program are presented in Table 7-6, while examples of the mineralization encountered by the Calamine drilling programs are presented in Table 7-7.

 

Table 7-5:      Summary of Zinc Mineralization, Extremo Norte and Lumiadeira/Sucuri Deposits

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Hole ID   From
(m)
    To
(m)
    Length
(m)
    Grade
(% Zn)
 
                         
Extremo Norte Deposit
MASAF001     218.25       224.90       6.65       6.49  
MASAF011     180.30       186.15       5.85       29.47  
MASAF016     288.20       292.90       4.70       20.37  
MASAF026     388.90       397.35       8.45       27.66  
MVZ490GTNP17350SF02     44.25       53.65       9.40       20.81  
MVZENP05N105WF01     131.50       140.45       8.95       22.21  
MVZENP05N105WF02     125.95       128.95       3.00       8.53  
MVZENP05N105WF03     103.10       113.40       10.30       13.91  
MVZENP05N105WF04     101.10       109.85       8.75       26.00  
MVZENP05N105WF05     80.00       96.00       16.00       20.04  
MVZENP05N217WF02     204.05       210.45       6.40       34.17  
MVZENP05N351WF01     341.50       344.80       3.30       39.31  
MVZENP06N111WF01     122.30       129.10       6.80       26.81  
MVZENP06N111WF02     116.90       122.10       5.20       26.78  
MVZENP06N111WF05     89.80       100.80       11.00       20.08  
MVZENP06N111WF06     78.55       81.20       2.65       32.98  
MVZGP585P17350SF01     124.30       129.05       4.75       30.91  
MVZGP585P17350SF02     118.35       124.15       5.80       29.62  
MVZGT585P17375SF01     29.05       35.05       6.00       23.66  
MVZGT585P17375SF02     28.00       35.50       7.50       36.35  
MVZGT585P17375SF03     32.80       41.60       8.80       26.12  
VZMIF152     88.65       97.95       9.30       5.28  

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Hole ID   From
(m)
    To
(m)
    Length
(m)
    Grade
(% Zn)
 
                         
Lumiadeira and Sucuri
MVZGP507P10412SF01     131.20       140.70       9.50       23.11  
MVZGP507P10412SF02     134.80       141.80       7.00       31.50  
MVZGP507P10412SF05     140.40       153.30       12.90       11.20  
MVZGP507P10412SF06     151.30       158.00       6.70       11.15  
MVZGP507P10425SF01     103.70       133.25       29.55       26.05  
MVZGP507P10425SF02     132.40       140.80       8.40       30.91  
MVZGP507P10425SF03     131.50       138.90       7.40       29.48  
MVZGP507P10425SF04     129.70       138.00       8.30       26.39  
MVZGP507P10425SF05     130.70       137.40       6.70       14.56  
MVZGP507P10425SF07     137.50       148.70       11.20       12.83  
MVZGP507P10425SF08     145.00       153.40       8.40       24.24  
MVZGP507P10425SF09     152.30       167.50       15.20       9.79  
MVZGT509SGV05F01     46.35       50.90       4.55       38.64  
MVZGT509SGV05F02     44.40       54.85       10.45       38.66  

 

Table 7-6:      Summary of Zinc Mineralization, Aroeira Tailings Drill Holes 

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Hole ID   From
(m)
    To
(m)
    Length
(m)
    Grade
(% Zn)
 
BRMVZBARP000038     0.00       12.00       12.00       3.84  
BRMVZBARP000040     0.00       4.80       4.80       4.06  
BRMVZBARP000042     0.00       3.60       3.60       3.43  
BRMVZBARP000044     0.00       3.60       3.60       4.87  
BRMVZBARP000046     0.00       7.20       7.20       4.06  
BRMVZBARP000048     0.00       24.00       24.00       3.61  
BRMVZBARP000050     0.00       18.00       18.00       3.65  
BRMVZBARP000052     0.00       14.40       14.40       3.23  
BRMVZBARP000054     0.00       25.20       25.20       3.70  
BRMVZBARP000056     0.00       25.20       25.20       4.40  
BRMVZBARP000058     0.00       21.60       21.60       3.44  
BRMVZBARP000060     0.00       22.80       22.80       3.91  
BRMVZBARP000062     0.00       13.20       13.20       4.00  

  

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Hole ID   From
(m)
    To
(m)
    Length
(m)
    Grade
(% Zn)
 
BRMVZBARP000064     0.00       4.80       4.80       5.03  
BRMVZBARP000066     0.00       16.80       16.80       3.93  
BRMVZBARP000068     0.00       9.60       9.60       3.95  
BRMVZBARP000070     0.00       4.80       4.80       4.31  
BRMVZBARP000072     0.00       4.80       4.80       4.05  
BRMVZBARP000074     0.00       8.40       8.40       4.72  
BRMVZBARP000076     0.00       12.00       12.00       4.33  
BRMVZBARP000078     0.00       22.80       22.80       4.30  
BRMVZBARP000080     0.00       22.80       22.80       4.53  
BRMVZBARP000082     0.00       18.00       18.00       4.07  
BRMVZBARP000084     0.00       22.80       22.80       3.99  
BRMVZBARP000086     0.00       20.40       20.40       4.90  
BRMVZBARP000088     0.00       19.20       19.20       4.64  
BRMVZBARP000090     0.00       24.00       24.00       3.68  
BRMVZBARP000092     0.00       25.20       25.20       4.03  
BRMVZBARP000094     0.00       22.80       22.80       3.99  
BRMVZBARP000096     0.00       16.80       16.80       4.38  
BRMVZBARP000098     0.00       19.20       19.20       4.65  
BRMVZBARP000100     0.00       22.80       22.80       5.53  
BRMVZBARP000102     0.00       21.60       21.60       5.77  
BRMVZBARP000104     0.00       20.40       20.40       5.90  

 

Table 7-7:      Example of Zinc Mineralization, Calamine Drilling 

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Hole ID   From
(m)
    To
(m)
    Length
(m)
    Grade
(% Zn)
 
BRBVZEND000005     95.87       105.84       9.97       10.20  
BRMVZCLD00005     8.12       11.19       3.07       18.11  
BRMVZCLD00007     10.69       18.36       7.67       23.57  
BRMVZCLD00007     20.14       20.19       0.05       48.18  
BRMVZCLD00007     46.12       46.76       0.64       13.65  
BRMVZCLD00008     24.31       29.30       4.99       6.12  
BRMVZCLD00008     38.03       47.48       9.45       6.01  

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Hole ID   From
(m)
    To
(m)
    Length
(m)
    Grade
(% Zn)
 
BRMVZCLD00008     50.02       51.63       1.61       10.70  
BRMVZCLD00010     28.99       31.30       2.31       3.76  
BRMVZCLD00010     36.00       48.37       12.37       6.39  
BRMVZCLD00011     29.88       30.48       0.60       9.63  
BRMVZCLD000114     25.00       25.99       0.99       45.60  
BRMVZCLD000119     51.79       52.02       0.23       1.13  
BRMVZCLD000119     57.70       58.88       1.18       1.44  
BRMVZCLD000119     67.29       82.36       15.07       16.80  
BRMVZCLD000119     87.19       89.42       2.23       1.13  
BRMVZCLD00012     10.85       14.19       3.34       13.06  
BRMVZCLD00012     15.38       18.02       2.64       22.38  
BRMVZCLD000120     22.90       26.59       3.69       29.89  
BRMVZCLD00013     34.39       35.45       1.06       9.85  
BRMVZCLD00013     36.90       38.15       1.25       18.25  
BRMVZCLD00013     42.36       47.49       5.13       12.90  
BRMVZCLD00013     50.51       53.00       2.49       3.04  
BRMVZCLD00014     50.75       58.24       7.49       25.54  
BRMVZCLD00015     19.36       32.28       12.92       7.67  
BRMVZCLD00017     11.97       18.96       6.99       11.28  
BRMVZCLD00017     24.78       27.25       2.47       34.86  
BRMVZCLD00017     35.05       36.04       0.99       5.03  
BRMVZCLD00019     51.98       60.70       8.72       26.52  
BRMVZCLD00023     4.93       15.89       10.96       16.68  
BRMVZCLD00023     17.68       21.71       4.03       31.12  
BRMVZCLD00023     24.78       27.92       3.14       8.28  
BRMVZCLD00024     43.91       47.06       3.15       23.06  
BRMVZCLD00025     4.97       7.60       2.63       0.90  
BRMVZCLD00025     9.10       14.82       5.72       0.16  
BRMVZCLD00025     16.90       17.70       0.80       6.02  
BRMVZCLD00025     18.49       19.80       1.31       3.44  
BRMVZCLD00025     21.31       22.19       0.88       3.72  
BRMVZCLD00027     49.71       54.54       4.83       11.63  
BRMVZCLD00030     45.02       48.30       3.28       10.61  

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Hole ID   From
(m)
    To
(m)
    Length
(m)
    Grade
(% Zn)
 
BRMVZCLD00030     51.50       55.43       3.93       2.94  
BRMVZCLD00031     6.81       11.39       4.58       10.59  
BRMVZCLD00036     45.06       71.08       26.02       19.81  
BRMVZCLD00037     36.73       43.58       6.85       6.73  
BRMVZCLD00037     53.02       67.01       13.99       16.02  
BRMVZCLD00040     48.45       60.03       11.58       6.06  
BRMVZCLD00042     49.90       57.13       7.23       6.14  
BRMVZCLD00044     52.19       75.80       23.61       15.62  
BRMVZCLD00044     82.04       85.46       3.42       7.98  
BRMVZCLD00046     46.28       60.54       14.26       21.80  
BRMVZCLD00049     50.51       51.19       0.68       0.27  
BRMVZCLD00049     57.57       60.99       3.42       0.65  
BRMVZCLD00049     66.23       70.47       4.24       2.83  
BRMVZCLD00049     72.17       81.94       9.77       18.50  
BRMVZCLD00049     86.34       89.98       3.64       14.76  
BRMVZCLD00051     43.00       55.86       12.86       10.51  
BRMVZCLD00055     42.73       56.01       13.28       1.03  
BRMVZCLD00055     61.00       62.19       1.19       7.35  
BRMVZCLD00061     62.96       73.10       10.14       11.68  
BRMVZCLD00065     84.49       93.66       9.17       13.20  
BRMVZCLD00068     47.23       57.00       9.77       16.91  
BRMVZCLD00068     61.28       65.53       4.25       14.61  
BRMVZCLD00072     42.45       47.01       4.56       16.02  
BRMVZCLD00072     49.62       54.60       4.98       9.13  
BRMVZCLD00072     57.60       66.45       8.85       7.38  
BRMVZCLD00078     65.20       69.22       4.02       29.43  
BRMVZCLD00086     61.78       65.31       3.53       25.40  
BRMVZCLD00090     54.45       55.45       1.00       5.88  
BRMVZCLD00098     74.30       78.49       4.19       21.15  
BRMVZCLD00101     47.70       49.70       2.00       9.23  
BRMVZCLD00101     55.36       58.99       3.63       5.47  
BRMVZCLD00107     44.03       47.01       2.98       4.82  
BRMVZCLD00107     47.74       49.01       1.27       7.55  

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Hole ID   From
(m)
    To
(m)
    Length
(m)
    Grade
(% Zn)
 
BRMVZCLR00001     57.99       59.00       1.01       3.22  
BRMVZCLR00001     66.97       69.07       2.10       8.75  
BRMVZCLR00001     71.99       81.97       9.98       21.32  
BRMVZCLR00001     86.15       88.74       2.59       7.13  
BRMVZCLR000115     20.01       27.01       7.00       39.41  
BRMVZCLR000134     66.02       67.00       0.98       3.91  
BRMVZCLR000134     69.00       70.00       1.00       3.11  
BRMVZCLR000139     85.99       90.00       4.01       3.48  
BRMVZCLR000139     92.00       95.11       3.11       3.28  
BRMVZCLR000152     65.00       70.99       5.99       12.39  
BRMVZCLR000161     56.00       56.99       0.99       3.50  
BRMVZCLR000162     45.00       61.00       16.00       7.43  
BRMVZCLR000163     39.04       47.00       7.96       7.03  
BRMVZCLR000164     53.98       56.02       2.04       5.20  
BRMVZCLR000167     47.94       48.99       1.05       8.71  
BRMVZCLR000173     15.02       16.98       1.96       19.73  
BRMVZCLR000173     23.00       25.99       2.99       31.08  
BRMVZCLR000173     30.00       46.97       16.97       9.36  
BRMVZCLR000174     4.05       4.99       0.94       3.83  
BRMVZCLR000174     20.01       20.99       0.98       25.50  
BRMVZCLR000174     32.00       33.00       1.00       27.30  
BRMVZCLR000174     49.00       50.00       1.00       3.17  
BRMVZCLR000177     42.99       44.01       1.02       11.05  
BRMVZCLR000177     45.00       46.00       1.00       4.18  
BRMVZCLR000178     40.03       44.00       3.97       28.37  
BRMVZCLR000179     56.03       63.98       7.95       6.49  
BRMVZCLR000180     94.01       99.99       5.98       41.14  
BRMVZCLR000184     11.03       14.00       2.97       11.09  
BRMVZCLR000184     16.00       19.60       3.60       8.00  
BRMVZCLR000184     19.81       32.04       12.23       10.84  
BRMVZCLR000184     33.98       38.99       5.01       25.22  
BRMVZCLR000184     43.02       52.95       9.93       15.43  
BRMVZCLR000185     15.00       17.01       2.01       6.69  

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

7-40

 

 

 

 

Hole ID   From
(m)
    To
(m)
    Length
(m)
    Grade
(% Zn)
 
BRMVZCLR000185     29.00       34.01       5.01       2.76  
BRMVZCLR000188     21.98       23.51       1.53       5.16  
BRMVZCLR000191     43.01       43.99       0.98       3.16  
BRMVZCLR000194     71.03       71.96       0.93       4.18  
BRMVZCLR000198     52.98       54.98       2.00       9.42  
BRMVZCLR000198     58.00       60.03       2.03       4.43  
BRMVZCLR000199     40.18       45.12       4.94       5.14  
BRMVZCLR000199     48.10       49.05       0.95       3.57  
BRMVZCLR000203     58.99       62.11       3.12       3.95  
BRMVZCLR000238     73.01       74.99       1.98       3.64  
BRMVZCLR000238     76.00       82.01       6.01       5.44  
BRMVZCLR000240     38.00       43.98       5.98       5.15  
BRMVZCLR00039     87.99       93.01       5.02       7.31  
BRMVZCLR00040     90.99       92.01       1.02       3.35  
BRMVZCLR00044     20.00       24.95       4.95       14.05  
BRMVZCLR00047     2.04       5.16       3.12       8.13  
BRMVZCLR00047     11.01       11.98       0.97       3.03  
BRMVZCLR00047     13.01       24.01       11.00       5.43  
BRMVZCLR00051     22.98       27.01       4.03       7.80  
BRMVZCLR00051     34.01       41.43       7.42       3.47  
BRMVZCLR00051     45.00       49.96       4.96       5.15  
BRMVZCLR00055     15.13       18.95       3.82       23.85  
BRMVZCLR00057     12.02       30.00       17.98       8.14  
BRMVZCLR00061     50.99       58.01       7.02       6.69  
BRMVZCLR00069     58.01       60.99       2.98       4.53  
BRMVZCLR00069     70.04       78.01       7.97       14.97  
BRMVZCLR00069     81.00       82.01       1.01       6.90  
BRMVZCLR00069     82.99       85.00       2.01       6.89  
BRMVZCLR00069     86.01       86.73       0.72       21.40  
BRMVZCLR00069     91.60       94.00       2.40       9.65  
BRMVZCLR00069     95.00       95.99       0.99       8.15  
BRMVZCLR00071     59.03       62.26       3.23       6.54  
BRMVZCLR00075     64.04       64.98       0.94       3.35  

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Hole ID   From
(m)
    To
(m)
    Length
(m)
    Grade
(% Zn)
 
BRMVZCLR00075     73.99       81.02       7.03       7.41  
BRMVZCLR00077     73.02       84.01       10.99       14.08  
BRMVZCLR00081     22.00       23.00       1.00       3.04  
BRMVZCLR00081     25.00       26.00       1.00       4.21  
BRMVZCLR00087     0.00       3.00       3.00       14.42  
BRMVZCLR00089     2.00       5.99       3.99       24.51  

 

There are no drilling, sampling, or recovery factors that could materially impact the accuracy and reliability of the results.

 

7.3 Geotechnical and Hydrogeology

 

Nexa uses a FEFLOW ground water model, which was last updated in 2019, as its primary water management tool for the Vazante Operations. Given the extreme dewatering that is required to permit ongoing mining, hydrologic monitoring is considered a critical element of operations. Continued calibration of flows is important to predict, plan, and install required pumping capacities for the Vazante Operations. The average dewatering rate has been estimated at approximately 13,000 m³/h to 15,000 m³/h.

 

Please see Section 12.4.2 for further information about Hydrogeology and Geotechnical Studies.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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8.0 Sample Preparation, Analyses, and Security

 

8.1 Sample Preparation and Analysis

 

8.1.1 Sampling Methods

 

8.1.1.1 Core Samples

 

Core boxes are transported daily to the core shed by personnel from the drilling company. Analytical samples are transported by company or laboratory personnel using corporately owned vehicles. Core boxes and samples are stored in safe, controlled areas.

 

Chain-of-custody procedures are followed whenever samples are moved between locations, and to and from the laboratory, by filling out sample submittal forms.

 

Nexa staff collect samples from drill core according to the following SOPs:

 

PO-VZ-GST-GEO-004-PT

 

PO-VZ-GST-GEO-006-PT

 

Core samples have a preferred length of one metre however length may vary from a minimum of 0.50 m and a maximum of 1.50 m, depending on the location of lithological, alteration, mineralization, or other natural boundaries or contacts. If core recovery is less than 100%, the length of the sample is considered as equivalent to the anticipated length. Nexa’s sampling protocols require that the logging personnel collect samples of drill core three metres above and three metres below mineralized intervals.

 

After sampling and sample description are completed and entered into the database, a sampling plan is prepared. That plan identifies assay and Quality Control (QC) sample locations and sample numbers. The QC samples are inserted and photographed prior to shipment as an aid to identification of those samples should problems occur.

 

Core samples from underground drill holes are not split, rather they are forwarded to the laboratory as whole core (typically BQ). Surface drill holes are split using a dedicated core saw. One half of the sample is forwarded to the laboratory, and the other half is placed into boxes and archived in the core shack. The unused sample material from the laboratory (coarse rejects and pulps) is retuned back to the mine site and is placed into identified boxes and stored into the core shack.

 

8.1.1.2 Channel Samples

 

Underground channel samples are collected according to Nexa’s SOP PO-VZ-GST-GEO-016-PT (Underground channel samples). Channel samples range from 0.5 m to 1.5 m in length, and respect lithological, alteration, mineralization, and other natural boundaries. Samples are collected with a hammer and chisel or battery powered hammer drill, approximately 1.2 m horizontally above the floor of the mine working. Sample material is placed in plastic bags along with a paper tag containing the appropriate sample number and are transported to surface.

 

8.1.1.3 Tailings Samples

 

The entire length of the samples was used for assaying purposes. The samples are nominally 1.2 m in length unless there are obvious changes in the sample material visible in the core.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000
Technical Report Summary - February 15, 2021

 

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8.1.2 Density Determinations

 

8.1.2.1 Drill Core

 

Prior to 2015, density was determined by means of the displaced volume method for all samples collected at the Vazante Operation. From the second half of 2015 onwards, there was a transition to the Jolly method (Archimedes method) and, due to the large number of data available, analyses were performed on only a few drill holes. The Jolly method relies on the fact that porosity of the samples is very low. For each determination, an entire sample is weighed in air in a plastic mesh bag, and then weighted while the sample is suspended in water in the mesh bag. This allows for very accurate determination of density of the entire sample rather than a small piece of the sample.

 

Currently, bulk density is determined for every sample that is selected for assaying using the Jolly method which is checked with the displaced volume method (Nexa SOP PO-VZ-GST-GEO-015-PT (Density Measurement)) procedure. As of April 30, 2020, the database has approximately 117,315 bulk density measurements for the Vazante Mine and 15,869 bulk density measurements for the Extremo Norte Mine, for a total of more than 133,000 density data.

 

Every 20th sample is checked by the displaced volume method. The displaced volume method requires that the sample be placed in a large container of water and allowed to overflow into another container. The overflow is then weighed. The weight of water is essentially equivalent to the volume in cm3 of the sample. Comparisons of the density values determined by the two methods have shown a good correlation and no systematic bias among the measurements via displaced volume and the Jolly method (Figure 8-1).

 

 

Source: Nexa.

 

Figure 8-1:Comparison of Bulk Density Measurements

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000
Technical Report Summary - February 15, 2021

 

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8.1.2.2 Tailings Samples

 

The bulk density of the tailings materials has been measured using the caliper method on the extracted cores and by in-situ measurements.

 

For the caliper method, the volume of the dried core samples is determined using calipers to estimate the average diameter of a segment of core for a measured length. The weight of the segment is determined by direct measurement. As of April 30, 2020, a total of 453 tailings bulk density measurements were collected using the caliper method.

 

For the in-situ method, the material from a known volume of tailings as determined by using a steel form of known volume is excavated from the surface of the Aroeira TSF and the material is allowed to dry. The dry weight is then measured. A total of 12 in-situ density samples were collected from the Aroeira TSF.

 

8.1.3 Analytical and Testing Laboratories

 

Prior to 2014, both the mine and exploration samples were analyzed at the on-site Vazante Operation laboratory. Samples were prepared using the mine laboratory equipment. SLR notes that the Vazante Operation laboratory is not accredited, and not independent of Nexa.

 

Currently, all operational samples from underground sampling (in-fill drilling programs and channel sampling) programs are analyzed at the ALS Global (ALS) laboratory facilities located in Vespasiano, Minas Gerais. All samples collected as part of the calamine drilling programs and the Aroeira tailings sampling programs were analyzed at the ALS facilities.

 

ALS, an independent laboratory, has been the primary laboratory for the preparation of exploration samples since 2014. Samples are prepared and analyzed at either of the ALS laboratories located in Vespasiano, Minas Gerais and Goiânia, Goiás. Both laboratories are ISO 9001:2008 certified (#FS571108).

 

ALS Lima, which is also independent of Nexa, was the primary analytical laboratory for exploration samples prior to 2014. The ALS Lima laboratory is ISO 9001:2008 and 17025:2005 accredited.

 

8.1.4 Sample Preparation

 

All exploration samples are currently prepared at ALS.

 

After samples are split at the core shed, they are sent to ALS Vespasiano in Belo Horizonte, Brazil where they undergo preparation following the ALS method code PREP-31. The procedure is as follows:

 

As samples are received at the laboratory, any differences between the number of samples indicated on the Analytical Request (RA) letter that accompanies the samples and what has effectively been received are reported, as well as any other anomalies.

 

Samples are weighed after they are checked against the RA letter.

 

Samples are dried in a kiln for eight hours to 12 hours, with maximum controlled temperature of 120°C.

 

The sample is crushed to 70% passing (P70) a 2-mm screen (9 mesh Tyler).

 

Samples are homogenized and split through a Jones type rifle splitter. Approximately 250 g is split for the analytical sample. The remaining fraction is stored as coarse reject.

 

Samples are pulverized until 85% of the particles pass a 75 μm (-200 mesh) screen.

 

The pulverized sample is bagged in kraft paper bags and sent to the laboratory for analysis.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000
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8.1.5 Analytical Methods

 

8.1.5.1 Vazante Operation Laboratory

 

Prior to mid-2014, chemical analyses at the Vazante Operation laboratory were performed using an X-ray fluorescence (XRF) technique and an atomic absorption spectroscopy (AAS) procedure for selected elements. Samples with zinc contents >6% were re-assayed with the AAS procedure.

 

The analytical procedures used by the Vazante Operation laboratory are summarized in Table 8-1.

 

Table 8-1:      Summary of Analytical Procedures for the Vazante Laboratory

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Parameter   Sample Type   Analytical Method   Standard Operating
Procedure
             
Ag   All   Aqua regia digestion followed
by atomic absorption
spectrometry
  PO-VZ-PRO-LAB-087-PT
Zn, Pb, Fe, CaO, MgO, Al2O3, SiO2   Stockpiles, Crusher, Ore Sorter, Bi-Hourly Zinc Concentrates   Pressed pellet followed by XRF   PO-VZ-PRO-LAB-032-PT
Zn, Pb, Fe, CaO, MgO, Al2O3, SiO2   Bulk Feed, Final Rejects, Final Products (Zinc and Lead Concentrates)   Pressed pellet followed by XRF   PO-VZ-PRO-LAB-104-PT
Mn, Cd, Mg, Na   Lead Concentrate   Aqua regia digestion followed
by atomic absorption
spectrometry
  PO-VZ-PRO-LAB-087-PT
Carbonate and S   Concentrates   Leco carbon and Sulphur infrared analyzer   PO-VZ-PRO-LAB-066-PT

 

8.1.5.2

ALS Chemex

 

The transition from XRF to inductively coupled plasma (ICP) and AAS began in 2014 when analyses for exploration samples began to be performed at the ALS laboratory in Lima. Selected elements were analyzed via AAS, while the same elements, and others, were analyzed with ICP atomic emission spectroscopy (AES). High grade zinc was analyzed specifically using a volumetric method for better results. From 2015 onward, all analyses have been performed at ALS Lima.

 

At ALS Lima, core and channel samples are dissolved using Method Code ME-ICP61 where the sample is submitted to a four acid digestion (HNO3–HCl-H2SO4-HF). The metal concentrations in the solutions are then determined using either an ICP-AES or AAS method. Both finishes are appropriate for the elements of potential economic interest as well as deleterious elements at the Vazante Operation. For those samples containing metal grades above the upper detection limits, the metal concentrations are determined by means of the following methods:

 

Metal ALS Method Code
Silver Ag-OG62 / Ag-GRA21
Copper Cu-OG62 / Cu – VOL61
Iron Fe-OG62
Lead Pb-OG62 / Pb-VOL70
Zinc Zn-OG62 / Zn-VOL70

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000
Technical Report Summary - February 15, 2021

 

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8.2 Quality Assurance and Quality Control (QA/QC)

 

Company wide QA/QC protocols implemented in 2009, are based on internal corporate standards (standard numbers PG-EXP-GTO-001-PT, PG-EXP-GTO-002-PT, and PG-EXP-GTO-003-PT.

 

8.2.1 Vazante Operation

 

The current Vazante Operation QA/QC program includes submission of twin, coarse and pulp duplicates, certified reference materials (CRMs), external controls, and coarse blank samples as shown in Table 8-2. Due to the unique nature of the mineralization found at the Vazante Operation, few options are available to purchase appropriate commercial CRMs for use in the QA/QC monitoring programs. Consequently, Nexa has prepared four internal CRMs from mineralized samples sourced from the Vazante and Extremo Norte deposits so that the CRMs are directly matched with the drill core and chip samples.

 

Table 8-2:      Summary of QA/QC Protocols

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Sample Type   Code   Insertion
Rate
(%)
  Insertion
Ratio
  Purpose
                 
CRM (Standard)   PD   5   1:20   Accuracy
Coarse Blank   BR   2   1:50   Contamination detection in sample preparation
Field Duplicate/Replicate   RP   1   1:100   Quality of sampling
Coarse Reject Duplicate   RG   1   1:100   Quality of sample preparation
Pulp Duplicate   DP   2   1:50   Precision
Interlaboratory Check   DC   2   1:50   Bias between laboratories - accuracy

 

For the period between July 1, 2019 and April 15, 2020, the Vazante Operation processed a total of 11,677 samples and inserted a total of 1,315 QA/QC samples (blanks, replicates, reject and pulp duplicates, CRMs, and external check assays), as summarized in Table 8-3.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000
Technical Report Summary - February 15, 2021 

 

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Table 8-3:      Summary of QA/QC Samples Processed from July 1, 2019 to April 15, 2020

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Item   Number of samples  
       
Blank Samples (ALS)  
       
Ag, Pb, and Zn   210  
Certified Reference Materials (ALS)  
CRM BRMVZSTD007 (Ag, Fe, Pb, and Zn)   141  
CRM BRMVZSTD008 (Ag, Fe, Pb, and Zn)   125  
CRM BRMVZSTD009 (Ag, Fe, Pb, and Zn)   123  
CRM VZ007 (Ag, Fe, Pb, and Zn)   106  
Duplicates  
Pulp Duplicates (Ag, Fe, Pb, Zn)   429  
Coarse Rejects (Ag, Fe, Pb, Zn)   87  
Replicates (Ag, Fe, Pb, Zn)   94  

 

SLR has reviewed the results from Nexa’s QA/QC program for the July 1, 2019 to April 15, 2020 period and notes that the results are within acceptable limits. Example control charts for the blank sample, CRMs, pulp duplicate, and replicate results are presented in Figure 8-2, Figure 8-3, Figure 8-4, and Figure 8-5, respectively.

 

 

 

Source: Nexa

 

Figure 8-2:        Zinc Blank Sample Control Chart, July 1, 2019 to April 15, 2020

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000
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Source: Nexa

 

Figure 8-3:      Zinc Standard Reference Material (BRMVZSTD007) Control Chart, July 1, 2019 to April 15, 2020

 

 

Source: Nexa

 

Figure 8-4:      Zinc Pulp Duplicate Sample Control Chart, July 1, 2019 to April 15, 2020

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000
Technical Report Summary - February 15, 2021 

 

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Source: Nexa

 

Figure 8-5:      Zinc Replicate Sample Control Chart, July 1, 2019 to April 15, 2020

 

8.2.2 Calamine Drilling

 

QA/QC programs were carried out during the course of the drilling campaigns carried out on the calamine mineralization in 2017, 2018, and 2019. The programs conformed to the requirements set out in Nexa’s SOPs PG-EXP-GTO-001-PT, PG-EXP-GTO-002-PT, and PG-EXP-GTO-003-PT. A summary of the number and type of QA/QC samples submitted, along with the submittal rates is provided in Table 8-4.

 

SLR has examined the results of the QA/QC data collected in relation to the drilling campaigns carried out on the calamine mineralization in 2017, 2018, and 2019 and notes that the results are within acceptable limits.

 

Table 8-4:      Summary of QA/QC Samples from the Calamine 2017, 2018, and 2019 Drilling Programs

Nexa Resources S.A. – Vazante Polymetallic Operations

 

                QA/QC Samples  
Year   Total
Samples
    Assays     Blank     Standard     Coarse
Duplicate
    Pulp
Duplicate
    Coarse
Reject
    Pulp
Reject
    QA/QC
Total
 
2017     9,196       8,116       162       403       0       360       79       76       1,080  
2018     6,955       6,015       118       315       81       310       68       48       940  
2019     3,983       3,555       66       126       0       165       65       6       428  
Total     20,134       17,686       346       844       81       835       212       130       2,448  

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000
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Year   % Total
Samples
    % Assays     QA/QC Insertion Rates  
2017     45.7       45.9       1.8       4.4       0       3.9       0.9       0.8       11.7  
2018     34.5       34.0       1.7       4.5       1.1       4.5       1.0       0.7       13.5  
2019     19.8       20.1       1.7       3.2       0       4.1       1.6       0.2       10.8  
Total     100       100       1.7       4.2       0.4       4.2       1.1       0.7       12.2  

 

8.2.3 Tailings Sampling

 

QA/QC programs were carried out during the course of the drilling campaigns for the tailings sampling programs. The QA/QC programs conformed to the requirements set out in Nexa’s SOPs PG-EXP-GTO-001-PT, PG-EXP-GTO-002-PT, and PG-EXP-GTO-003-PT.

 

The QA/QC programs included the use of two standard reference materials (BRMVZSTD001, 34 samples, and BRMVZSTD002, six samples), blank samples (eight samples), and pulp duplicate assaying of 28 samples.

 

SLR has examined the results of the QA/QC data collected in relation to the drilling campaigns carried out for the tailings sampling programs and notes that the results are within acceptable limits.

 

8.2.4 Survey QA/QC

 

QC data for total station surveys consist of closed loops for all surveys, both surface and underground. Quality control for Digital Global Positioning System (DGPS) surveys rely on duplicate surveys as well as repeated surveys of known points at the beginning and end of each survey day.

 

Downhole drill hole deviation survey QC data consist of duplicate surveys for all holes.

 

8.2.5 Databases

 

Fusion™, a database management software package sold and supported by Datamine™ is used for database management at the Vazante Operations. Fusion™ provides reliability and traceability assurance as well as an easy interface with Datamine™ modeling and mine planning software. The login is password protected by individual personnel and all personnel have the permission necessary to complete their tasks. Three people in the company have unlimited access to the database. Data cannot be entered or changed in the database without the appropriate permission. There is an expert in charge of the database full time to make certain that data are reliable and to provide data extraction and editing services.

 

Primary data entered by the site geologists into the tablet devices are imported directly into Fusion™. Analytical data are provided digitally by the assay laboratories.

 

All data stored in the Fusion™ database are verified via software verification before final entry into the database. These automatic routines are aimed at preventing entry of extraneous data such as incorrect lithology codes or overlapping assay intervals into the database. They are largely successful; however, these checks are not perfect and additional internal checks are made to ensure that information used for Mineral Resource estimation and mine planning is as nearly correct as possible. Nexa’s internal corporate SOP PO-EXP-GRM-001-PT, requires additional checking of the following items:

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000
Technical Report Summary - February 15, 2021 

 

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Maximum and minimum grade values,

 

Negative values,

 

Detection limits and null values,

 

Drill hole surveys,

 

Unreasonable sample length,

 

Sample gaps,

 

Sample overlaps,

 

Drill hole collars versus topography,

 

Coordinate datum,

 

Verification of mining permissions, and

 

Laboratory analysis certificates.

 

Each of these items are checked and if discrepancies are discovered, verified, and corrected if necessary.

 

Primary original documents and logs, downhole surveys, core photographs, and assay certificates are stored on network drives. Digital copies of the database network drives are routinely backed-up daily, weekly, and monthly.

 

In the SLR QP’s opinion, the sample preparation, analysis, and security procedures at the Vazante Operation are adequate for use in the estimation of Mineral Resources.

 

In the SLR QP’s opinion, the QA/QC program as designed and implemented by Nexa is adequate and the assay results within the database are suitable for use in preparation of a Mineral Resource estimate.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000
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9.0 Data Verification

 

Validation of the Vazante Operation geological data by SLR began with an inspection conducted during the November 19 to 23, 2018 site visit. During this site visit, the SLR QP visited the core shack where examples of the mineralization from both the Vazante and Extremo Norte deposits were inspected, logging and sampling procedures reviewed, and visits carried out to the sample sawing and density measurement facilities. Visits were made to several locations in the underground mines in which the nature of the mineralization was observed and the grade control mapping and sampling procedures were discussed. Discussions were carried out with site geological staff in regards to the regional and local scale geology as well as reconciliation activities carried out by the mine staff.

 

SLR also visited some of the mine stockpile areas, in addition to conducting a brief tour of the processing plant to inspect the sampling points used to determine the tonnages and grades processed. A visit was made to the site sample preparation facility as well as the site assay laboratory.

 

In addition to personal inspections of Vazante, SLR carried out a program of validating the assay tables in the drill hole databases by means of spot checking a selection of drill holes that intersected the mineralization of the Vazante, Extremo Norte, Aroeira TSF, and calamine deposits. SLR proceeded to carry out its drill hole database validation exercise by comparing the information contained within the assay tables of the digital databases against the assays presented in the original laboratory certificates. Comparisons of the lithological information contained within the drill logs against the information contained within the digital databases were also carried out, as was a comparison of the results of the down-hole deviation measurements with those contained within the survey table of the drill hole database.

 

While examining the information contained within the assay tables of the Vazante and Extremo Norte deposits, a small number of cases were discovered where the zinc assay values contained within the drill hole database did not agree with and were, in general, lower than the values provided in the assay certificates. After preliminary discussions with Nexa, SLR agrees that this may be a result of additional assaying that may have been carried out for those samples but for which the corresponding assay certificates could not be located.

 

A small number of discrepancies were discovered while comparing the results of the down-hole deviation measurements with those contained within the survey table. The discrepancies consisted of a disagreement in the sign of the drill hole dips between the original survey records and the records contained within the survey table in the drill hole database. Visual inspection of the drill holes in cross section views suggested that the drill holes in question are in good spatial agreement with the adjoining drill hole and channel sample data. Discussions with Nexa indicate that the source of the discrepancies may be related to the implementation of the new drill hole database, as the dip conventions were modified at that time.

 

SLR recommends that the drill hole dips for the drill holes examined be confirmed by direct visual inspection of the departing drill hole orientation at the drilling face.

 

Additional checks included a comparison of the drill hole collar locations with the digital models of the topographic surfaces and excavation models as well as a visual inspection of the downhole survey information. A small number of cases were observed where the collars of some of the underground based drill hole collars were in poor agreement with the excavation models. The collar locations of these drill holes were corrected prior to their use in preparation of the Mineral Resource estimate.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000
Technical Report Summary - February 15, 2021 

 

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Considering the long production history of the Vazante Operation, the style of mineralization, and the visual confirmation of the mineralization both at the mine faces and in drill core, no samples were collected by the geological QP for check sampling.

 

The SLR QP is of the opinion that geological data verification procedures for the Vazante Operation comply with industry standards and are adequate for the purposes of Mineral Resource estimation.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000 

Technical Report Summary - February 15, 2021

 

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10.0 Mineral Processing and Metallurgical Testing

 

10.1 Summary

 

The Vazante Operation currently produces and processes ore in which the main zinc mineral is willemite, a zinc silicate mineral (Zn2SiO4). During earlier Vazante operations, the predominant zinc mineralization occurred as calamine, which consists of both smithsonite (ZnCO3) and hemimorphite (Zn4Si2O7(OH)2·H2O), derived from weathering of the primary willemite mineralization and sourced from open pit supergene mineralization. Open pit mining operations of willemite mineralization were suspended in 2000, followed by the suspension of open pit production of calamine mineralization in 2008. Calamine ore is no longer produced and processed at the Vazante Operation. Development of the underground mines began in 1983, with initial minor production of willemite mineralization taking place in 1984. The underground mines exploit the primary willemite mineralization with minor to trace amounts of sphalerite. Production from the Vazante and Extremo Norte underground mines is ongoing. Treatment of calamine ores was more challenging than willemite ores with zinc recovery from calamine ores typically approximately 50%, while zinc recovery from willemite ores typically ranges from approximately 81% to 91%.

 

Zinc is the primary metal of economic importance, with minor quantities of lead as galena and associated silver minerals allowing for the production of relatively small amounts of lead concentrate as well. Due to the ore mineralogy, zinc concentrate produced at the Vazante Operation is elevated in silica, as well as calcium, magnesium, and carbonates resulting from carbonate gangue presence (predominantly dolomite). Nexa’s Três Marias zinc smelter includes a circuit specifically configured to process the zinc silicate concentrate produced at the Vazante Operation and as a result all of the concentrate produced at the Vazante Operation is exclusively processed at the Três Marias smelter where zinc metal is produced.

 

Test work completed on the Vazante Operation willemite ores prior to 2017 is described in the Amec 2017 NI 43-101 Technical Report (Amec, 2017). Much of the test work was conducted in the Nexa laboratory at the Vazante Operations. Work was also supported by universities including the Federal University of Minas Gerais (UFMG) and the University of Sao Paulo. SLR notes that test work completed on historically mined calamine ores was not discussed in Amec (2017). Test work on willemite ores, however, indicated that the willemite ores are relatively hard with Bond ball mill work indices (BWi) ranging from 19.6 kWh/t to 21.1 kWh/t for the samples tested, and that zinc recovery was sensitive to grind size. A strong correlation between zinc head grade and zinc recovery was found in flotation test work, and production of an acceptable grade lead concentrate was challenging to produce at low lead head grades, particularly for Extremo Norte samples.

 

10.2 Recent Test Work

 

Recent test work has focussed on the reprocessing of historical tailings and improving recovery from calamine material (versus historical recovery) to support calamine resource evaluation. The Aroeira TSF contains both willemite and calamine tailings, with the willemite tailings generally deposited on top of the calamine tailings. The Vazante Operation currently processes tailings reclaimed by truck and front end loader (FEL) from the Aroeira TSF. Aroeira tailings comprise a small portion of the feed to the processing plants. The current practice of reclaiming historical tailings involves selectively reclaiming willemite tailings while avoiding calamine tailings as much as possible. Nexa estimates that the Aroeira tailings consist of approximately 60% willemite tails and 40% calamine tails. Processing of calamine ore was historically characterized by poor recovery (approximately 50%), and it is thought that reprocessing of the calamine tailings might be best accomplished using a new collector or process that would improve on the historical recovery. Preliminary test work was completed on calamine samples by Nexa at the Vazante Operations with the objective of improving on the historical recovery from calamine ore with bench scale tests completed in 2017, followed by pilot tests in 2018.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000 

Technical Report Summary - February 15, 2021

 

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10.2.1 Aroeira Tailings Test Work

 

In 2019, SGS GEOSOL in Vespasiano, Brazil, (SGS GEOSOL, 2019), an independent laboratory certified to ISO 9001, ISO 14001, and ISO 17025, completed a pilot flotation study using a willemite tailings sample of approximately 29 t from the Aroeira TSF. The composition of the tailings sample is presented in Table 10-1. The objective of the test work was to produce a zinc concentrate containing 39% Zn at a minimum recovery of 55% of the contained zinc. After drying, the sample was screened at 2 mm and the +2 mm portion weighed 164 kg. The size distribution of the remainder of the sample indicated that it was approximately 47% +150 µm. In addition, approximately 71% of the zinc was found in the +150 µm portion of the sample. Semi-quantitative mineralogical analysis indicated that the main minerals present in the sample were hematite, dolomite, willemite, and quartz.

 

To prepare sample material for flotation test work, the sample was classified and ground in a circuit consisting of a spiral classifier and pilot ball mill. The grind target was set to approximate the typical granulometry of flotation feed at the Vazante Operation of between 88% passing and 92% passing 150 µm.

 

Preliminary rougher flotation test work using a mechanical cell and a column cell was conducted to compare the performance of the two types of cells, and to evaluate the effect of pH and reagent dosages (including dispersant, activator, collector, and frother), as well as the solids feed rate and air addition rate. Results demonstrated that at optimum conditions, the column cell performed better than the mechanical cell. The mechanical cell produced a rougher concentrate containing 17% Zn at a recovery of 68%, while the column cell produced a rougher concentrate containing 30% Zn at a recovery of 64% with lower activator and collector dosages, and no addition of frother.

 

Table 10-1:         Pilot Study Aroeira Tailings Sample Composition

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Element / Compound   %  
Zn     4.91  
Pb     0.43  
Cu     0.03  
S     0.06  
Fe2O3     47.50  
CaO     12.5  
MgO     8.46  
SiO2     4.54  
Al2O3     0.78  
K2O     0.07  
P2O5     0.07  
MnO     0.07  
TiO2     0.03  
LOI     19.4  
Ag     8 ppm  

 

Source: SGS GEOSOL, 2019

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000 

Technical Report Summary - February 15, 2021

 

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Closed circuit tests were conducted using rougher (column cells), scavenger (either column or mechanical cells), and cleaner (column cells) circuits, or just rougher and cleaner circuits using column cells. The best results, zinc recoveries of approximately 64% and concentrate grades 42% to 43%, were achieved at lower feed rates and higher reagent dosages, however, tests at higher feed rates and lower reagent dosages were also able to exceed the target recovery and concentrate grade. The best results achieved, i.e., 64% zinc recovery and 43% concentrate grade, used rougher and cleaner columns without any scavenger step. It was noted that concentrate quality and recovery were particularly sensitive to the addition of the sodium sulphide activator with higher dosages producing the best results.

 

Based on the pilot plant test work, a flowsheet consisting of trash and oversize removal, grinding, conditioning, and rougher and cleaner flotation using columns, has been proposed as a stand-alone circuit for processing larger quantities of willemite tailings from the Aroeira TSF.

 

Variability test work on samples taken from different areas of the Aroeira TSF was underway at the Vazante Operation at the time of writing this Technical Report Summary, using a mechanical cell to produce rougher concentrates. Preliminary results were similar to the mechanical cell rougher results from the 2019 SGS test work and it is anticipated that an improvement in performance similar to that achieved at SGS through the use of column flotation can be realized. Results of the variability test work completed to date are summarized in Figure 10-1.

 

 

Source: Nexa, 2020

 

Figure 10-1:     Rougher Variability Test Work Results

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000 

Technical Report Summary - February 15, 2021

 

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10.2.2 Calamine Test Work

 

In addition to calamine tailings contained in the Aroeira TSF and older tailings deposits, Nexa has identified potential calamine resources along the strike length, but mostly in the Extremo Norte deposit area. Results of test work completed at the Vazante Operation in 2017 and 2018 are summarized in the 2018 Nexa report, Alternativa Tecnológica para Tratamento de Calamina (Nexa, 2018).

 

Bench scale tests completed in 2017 on calamine samples from the Extremo Norte area indicated that there was potential for improvement over historical performance while processing calamine ores. Open circuit rougher-scavenger tests indicated that it was possible to reach approximately 23% Zn in concentrate at a recovery of up to 70%. An open circuit cleaner test produced a concentrate grading 39% Zn and a recovery of 63%. This test work was followed up with pilot test work at Vazante Mine with the objective of evaluating circuit configuration, different reagents and dosages, and the effect of closed-circuit operation on recovery and concentrate grade.

 

For the pilot plant test work, a bulk sample of approximately 20 t was collected from the historical calamine pit 3A in the Extremo Norte area. The sample was crushed and ground to approximately 88% passing 150 µm (approximately 80% passing (P80) 100 µm), similar to the current willemite flotation feed size, in preparation for flotation testing. Zinc content of the sample was approximately 13.4% Zn. The size distribution of the flotation feed sample indicated that approximately 35% of the feed was < 38 µm. X-ray Diffraction (XRD) analysis of a portion of the sample indicated that it consisted predominantly of smithsonite with secondary minerals including hemimorphite and quartz, typical of calamine mineralization. Additional bench scale rougher tests were used to assess the response of the calamine sample to different collectors and modifiers prior to starting the pilot tests. These tests indicated that a combination of amine collector and fatty acids significantly improved flotation response, with an emulsion of amine collector and rice oil producing the best results, and this was therefore selected for use in the pilot tests.

 

For the pilot tests, feed material was first classified to remove fines. Fines rejection was measured by mass loss, and two mass loss or rejection targets were applied, 20% and 30%. Tests using samples from which 30% of the mass had been rejected resulted in higher concentrate grades and recoveries than the tests using samples from which 20% of the mass had been rejected. Overall zinc recovery (i.e. recovery from flotation while accounting for zinc loss to the fines prior to flotation) of up to 50% at concentrate grades over 37% was shown to be possible with the samples from which 30% of the mass had been rejected. The best results were achieved using a circuit consisting of one rougher stage followed by two scavenger stages and with three cleaner stages. Cells used were conventional mechanical cells. Overall recovery for the samples from which 20% of the mass had been rejected was lower and the tests were also not able to achieve acceptable concentrate grades. XRD analysis of pilot plant tails indicated that the majority of zinc in the tails was present as hemimorphite. Nexa noted that the use of column cells rather than mechanical cells could provide some improvement in yield due to the large proportion of fines in the feed, and that further assessment of collectors and fatty acids was necessary to improve the recovery of hemimorphite.

 

SLR recommends that Nexa consider options that may help to improve recovery from calamine mineralization such as:

 

· Separate processing of calamine and willemite mineralization.

 

· A coarser primary grind for calamine mineralization and evaluation of the effect of a coarser primary grind on the proportion of fines in the flotation feed and zinc (and zinc mineral) deportment to fines.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000 

Technical Report Summary - February 15, 2021

 

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· Separate processing of the fines fraction to recover hemimorphite in a purpose-built fines processing circuit, which could also be used for processing historical calamine tailings.

 

10.3 Current Performance

 

Vazante Operation concentrate production for the past four years is summarized in Table 10-2.

 

Table 10-2:     Vazante Historical Performance

Nexa Resources S.A. – Vazante Polymetallic Operations

 

    Actual  
Description   Units   2017     2018     2019     2020  
Plant Throughput   000 tpa     1,321       1,374       1,407       1,623  
Head Grades   %Zn     12.3       12.1       11.5       10.4  
    %Pb     0.34       0.34       0.31       0.36  
    g/t Ag     17.3       19.1       17.6       19.5  
                                     
Zinc Concentrate   tpa     351,377       357,469       353,669       372,322  
Grade   %Zn     38.8       39.4       39.3       39.8  
Recovery   %Zn     83.9       84.5       86.2       87.5  
                                     
Lead Concentrate   tpa     6,027       5,025       4,052       5,069  
Grade   %Pb     25.4       26.4       23.2       26.3  
    g/t Ag     2,442       2,702       2,709       2,329  
Recovery   %Pb     33.8       28.7       21.5       22.5  
    %Ag     57.3       50.8       42.1       37.3  

 

10.4 Deleterious Elements

 

10.4.1 Zinc Concentrate

 

The Três Marias smelter, owned by Nexa, processes all zinc concentrate produced by the Vazante Operation in its zinc circuit designed to process zinc silicate concentrate. Target zinc content in the concentrate is 39% Zn. Elements or compounds that negatively affect the refining process include carbonates, magnesium oxide (MgO), and fluorine. The carbonate specification for the zinc concentrate is < 13.3% CO3, the MgO specification is < 4.5% MgO, and the fluorine specification is < 250 ppm F. Typical Vazante Operation concentrate contains levels of carbonates, MgO, and fluorine close to but under these limits.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000 

Technical Report Summary - February 15, 2021

 

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10.4.2 Lead Concentrate

 

Nexa reports that the lead concentrate grade is approximately 20% Pb to 28% Pb and does not contain penalty levels of deleterious elements. Silver content ranges from approximately 2,000 g/t Ag to 3,000 g/t Ag. The Vazante Operation lead concentrate is subject to a penalty charge of less than US$1.00/t due to the low lead content.

 

In the SLR QP’s opinion, the metallurgical recovery data is adequate for the purposes of Mineral Resource and Mineral Reserve estimation in this Technical Report Summary.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000 

Technical Report Summary - February 15, 2021

 

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11.0 Mineral Resource Estimates

 

11.1 Summary

 

For this Technical Report Summary, SLR has reviewed the Mineral Resource estimates of the Vazante Operation as prepared by Nexa as of December 31, 2020. SLR carried out a number of checks to verify the various procedures and numerical calculations used in the Nexa estimates. The checks included detailed reviews of the geological and mineralization interpretations, detailed tracing of the parameters and methodology used for estimating the tonnage and grades of the mineralized blocks, analysis of the conceptual operational scenarios, and consideration that the “Reasonable Prospects for Economic Extraction” requirement of S-K 1300 is met.

 

The Mineral Resources comprise three styles of mineralization. The first style of mineralization is represented by the hypogene (willemite) mineralized zones that are found in the underground portions of the Vazante and Extremo Norte deposits. The second style of mineralization is represented by the supergene (calamine) mineralized zones found in the Cava 3A, Mata dos Paulistas, and Braquiara areas of the Extremo Norte and Vazante deposits. This supergene (calamine) mineralization is referred to at the Vazante Operation as calamine mineralization and comprises a mixture of smithsonite and hemimorphite minerals. The third type of mineralization comprises tailings that are contained within the Aroeira TSF. The material found in the Aroeira tailings comprise a mixture of hypogene (willemite) and supergene (calamine) minerals.

 

The 2020 year end (YE) Mineral Resources as of December 31, 2020 for the Vazante Operation are presented in Table 11-1. Mineral Resources have been classified in accordance with the definitions for Mineral Resources in S-K 1300, which are consistent with CIM (2014) definitions. The Mineral Resources are exclusive of Mineral Reserves. The Mineral Resource statements for the underground hypogene (willemite) mineralization are prepared within reporting panels that have been created so as to achieve the required spatial continuity, cut-off grade, and minimum width criteria. The Mineral Resource statements for the supergene (calamine) mineralization are prepared using an open pit shell. The Mineral Resource statements for the tailings are reported using the original topographic surface as a constraint.

 

The Mineral Resource statements are prepared using Net Smelter Return (NSR) cut-off values that consider such items as the envisioned mining method, metallurgical recoveries, metal prices, etc. The NSR cut-off values are as follow:

 

Mineralization Type   Mining Method   NSR Cut-Off Value (US$/t)  
           
Hypogene (willemite)   Sub-level stoping
Room-and-pillar
  47.49
74.96
 
           
Supergene (calamine)   Open Pit – Rock
Open Pit - Soil
  24.64
23.39
 
           
Tailings   Truck-and-shovel     20.62  

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000 

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Table 11-1:     Summary of Mineral Resources as of December 31, 2020

Nexa Resources S.A. – Vazante Polymetallic Operations

 

        Grade     Contained Metal  
Category   Area   Tonnes
(000 t)
    (% Zn)     (% Pb)     (g/t Ag)     (000 t Zn)     (000 t Pb)     (000 oz Ag)  
Measured   Vazante & Extremo Norte     3,400       6.91       0.18       8.4       235.0       6.2       918  
    Calamine     0       0.00       0.00       0.0       0.0       0.0       0  
    Tailings     0       0.00       0.00       0.0       0.0       0.0       0  
Subtotal, Measured         3,400       6.91       0.18       8.4       235.0       6.2       918  
                                                             
Indicated   Vazante & Extremo Norte     2,000       5.84       0.13       7.6       117.0       2.6       489  
    Calamine     880       9.13       0.16       1.2       80.3       1.4       34  
    Tailings     0.00       0.00       0.00       0.0       0.0       0.0       0.0  
Subtotal, Indicated         2,880       6.85       0.14       5.6       197.3       4.0       523  
                                                             
Meas. & Ind.   Vazante & Extremo Norte     5,400       6.52       0.16       8.1       352.0       8.8       1,407  
    Calamine     880       9.13       0.16       1.2       80.3       1.4       34  
    Tailings     0.00       0.00       0.00       0.0       0.0       0.0       0.0  
Subtotal, M&I         6,280       6.88       0.16       7.1       432.3       10.2       1,441  
                                                             
Inferred   Vazante & Extremo Norte     9,040       7.79       0.17       11.0       704.0       14.9       3,190  
    Calamine     870       9.92       0.09       1.1       86.3       0.8       31  
    Tailings     3,939       4.06       0.25       7.8       159.9       9.8       995  
Subtotal, Inferred         13,849       6.86       0.18       9.5       950.2       25.5       4,216  

 

Notes:

 

1. The definitions for Mineral Resources in S-K 1300 were followed for Mineral Resources which are consistent with CIM (2014) definitions.

2. Mineral Resources are reported on a 100% ownership basis.

3. Mineral Resources are estimated at various NSR cut-off values appropriate to the mineralization style.

4. Mineral Resources are estimated using average long term metal prices of Zn: US$2,869.14/t (US$1.30/lb), Pb: US$2,249.40/t (US$1.02/lb), and Ag: US$19.38/oz, and metallurgical recoveries are based on recovery curves derived from historical processing data. An average long term R$/US$ exchange rate of 4.84 was used.

5. A minimum mining width of 3.0 m was used to create Mineral Resource reporting shapes for the willemite mineralization.

6. Mineral Resources are exclusive of Mineral Reserves.

7. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability.

  8. Numbers may not add due to rounding.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000 

Technical Report Summary - February 15, 2021

 

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11.2 Hypogene Mineralization (Willemite)

 

11.2.1 Resource Database

 

Information collected from surface-based drilling, underground-based drilling, and channel samples collected from the grade control program are all entered into a FusionTM master database that is used for database management at the Vazante Operations. The Fusion™ database was implemented in 2017. The login is password protected by individual personnel and all personnel are assigned the permission levels necessary to complete their tasks. Three people in the company have unlimited access to the database. Data cannot be entered or changed in the database without the appropriate permission. There is a full time expert in charge of the database to make certain that the data is reliable and to provide data extraction and editing services.

 

Primary data are entered by the site geologists into the tablet devices and are imported directly into Fusion™ database. Analytical data are provided digitally by the assay laboratories and are merged with the data from the geologists. Primary original documents and logs, down-hole surveys, core photographs, and assay certificates are stored on network drives. Digital copies of the database network drives are routinely backed-up daily, weekly, and monthly.

 

All data stored in the Vazante Operation database are verified using various software verification routines before final entry into the database. These software verification routines are aimed at preventing the entry of extraneous data such as incorrect lithology codes or overlapping assay intervals into the database. While largely successful, these checks are not perfect and additional internal checks are made to ensure that information used for Mineral Resource estimation and mine planning is as nearly correct as possible. Nexa’s internal corporate standard operating procedure PO-VM-GRM-001, requires additional checking of the following items:

 

· Sample length problems

 

· Maximum and minimum grade values

 

· Negative values

 

· Detection limits and null values

 

· Drill hole surveys

 

· Sample size

 

· Gaps

 

· Overlaps

 

· Drill hole collars versus topography coordinate datum

 

· Verification of mining permissions

 

· Laboratory analysis certificates

 

Each of these items are checked and if discrepancies are discovered, verified, and corrected, as necessary.

 

Drill hole and channel sample information were extracted into two separate data subsets for the preparation of the Mineral Resource estimates for the hypogene mineralization found at the Vazante Mine. One database subset was constructed to include the mineralization found in the Lumiadeira and Sucrui segments of the Vazante portion of the mineralization. The second database subset was constructed to include the mineralization found in the Extremo Norte region of the Vazante Mine.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000 

Technical Report Summary - February 15, 2021

 

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Drill hole and channel sample information for the Vazante Mine was extracted from this internal database into separate files for use in preparation of the Mineral Resource estimates. This drill hole information was modified slightly so as to be compatible with the format requirements of Datamine and Leapfrog modelling packages and were imported into those software packages by Nexa. A number of new tables and variables were created during the estimation process to capture such information as the interpreted mineralized intersection length along the drill holes, density readings, capped assay values, and composite values.

 

The cut-off date for the assays in the drill hole database is April 30, 2020. Drilling and sampling was carried out using the UTM Datum Cόrrego Alegre, Zone 23S grid coordinate system. The northing and easting collar coordinates of the drill holes and channel samples used to prepare the Mineral Resource estimate for the hypogene mineralization were modified from the UTM coordinate system to the mine grid coordinate system. No changes were made to the collar elevations, and no rotations or scaling factors were applied. The conversion factors from UTM to mine grid are shown below:

 

Easting (X): UTM grid – 300,000 = Mine grid

 

Northing (Y): UTM grid – 8,000,000 = Mine grid

 

A summary of the drilling and channel sampling information is provided in Table 11-2. The location of the drill holes and channel samples are presented in Figure 11-1.

 

Table 11-2:     Summary of Drill Hole and Channel Sample Databases, Vazante and Extremo Norte

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Data Type     No. of Records – DDH       No. of Records – Channels  
             
Vazante
Collars     6,186       1,088  
Down hole survey     218,582       5,665  
Lithology     86,846       3,227  
Assays     126,435       5,665  
Composites (within mineralized wireframe boundaries)         46,039      
Density         17,315      
Extremo Norte
Collars     1,398       198  
Down hole survey     96,694       1,031  
Lithology     18,704       540  
Assays     36,532       1,031  
Composites (within mineralized wireframe boundaries)         10,062      
Density         16,758      

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000 

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Figure 11-1:     Drill Hole and Channel Sample Locations, Vazante and Extremo Norte Deposits

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000 

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11.2.2 Mineralized Wireframe Interpretation

 

The mineralized wireframe interpretations were prepared by Nexa staff in consideration of all geological and assay information collected from drilling and channel sample information, information collected from the grade control geological mapping and sampling activities, and from practical experience gained over the many years of production history of the Vazante Operation. The broader-scale lithological features in both the Vazante and Extremo Norte deposits (such as the hydrothermal breccia unit) were used as guides in the preparation of the mineralized wireframe interpretations.

 

The mineralized wireframe interpretations adopted a three tier approach that was based on the zinc cut-off grade and the style of the mineralization. All mineralized wireframe outlines were prepared using the Leapfrog software package. A series of mineralized wireframe outlines were prepared at a cut-off grade of 5% Zn for those mineralized intervals considered to be part of the primary style of willemite mineralization that is located generally along the footwall contact of the mineralized system in association with the Vazante Shear.

 

The second series of mineralized wireframes were also prepared using a cut-off grade of 5% Zn, however, these wireframes included mineralized intervals that are present in the stratigraphic package but are not considered to form part of the main mineralized trend. In general terms, the secondary mineralized zones comprise stringer and breccia style mineralized intervals and are located on the hanging wall side of the primary mineralized zones. Occurrences of secondary style mineralization, however, are also present in the footwall of the primary mineralized zones.

 

The third series of mineralized wireframes were prepared using a cut-off grade of 2% Zn. These tertiary mineralized wireframes include lower grade mineralized intervals that are present in the immediate wall rocks to either the primary or secondary mineralized wireframes.

 

For each of the mineralized wireframes, no minimum widths were applied. This approach is part of an overall strategy in which the minimum width criteria is considered by application of reporting panels as one of the criteria when preparing the Mineral Resource statements.

 

While lead and silver also form part of the hypogene mineralization found at the Vazante Mine, their contributions to the overall value of the mineralization are minor in comparison with the revenue that is achieved from the zinc content (Figure 11-2). Consequently, the cut-off grade used to prepare the mineralized wireframe interpretations is based on a simple zinc-alone basis.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Figure 11-2:      Relative Value by Metal, Willemite Mineralization

 

The hypogene zinc mineralization at the Vazante Mine has been traced by drilling and channel sampling along a strike length of approximately 10.5 km and from surface (elevation approximately 750 m AMSL) to elevation of approximately 0 m AMSL, a distance of approximately 750 m (Figure 11-3). A sample cross section is provided in Figure 11-4. Additional cross sections are provided in Section 7.2 of this Technical Report Summary.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Figure 11-3:            View of the Mineralized Wireframe Outlines, Willemite Mineralization

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Figure 11-4:          Sample Cross Section of the Mineralized Wireframes, Vazante Mine

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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11.2.3 Topography and Excavation Models

 

11.2.3.1 Topography Surfaces

 

Three topographic surfaces are used at the Vazante Mine (Figure 11-5). The first topographic surface is constructed from satellite based data that is made available through the Brazilian government agencies. This general topographic map provides coverage for a wide area around the Vazante Mine and is used as a general guide for field activities such as regional exploration and planning purposes for surface-based drilling programs targeting the hypogene mineralization. The precision and accuracy of this topographic surface is limited to several metres, especially when dealing with elevation data.

 

The second topographic surface is constructed by the Nexa mine staff from data collected using various detailed surveying methods such as drone based LIDAR topography measurements or total station survey equipment. This detailed topographic information provides coverage for approximately half of the strike length of the Vazante portion of the mineralized trend and provides information relating to the open pit excavations that have taken place on the Vazante portion of the mineralized trend.

 

The third topographic surface is constructed by the Nexa mine staff using various detailed surveying methods such as drone based LIDAR topography measurements or total station survey equipment. This topographic surface has an effective date of April 24, 2019 and provides information relating to the open pit excavations that have taken place for the Extremo Norte portion of the mineralized trend.

 

11.2.3.2 Excavation Models

 

Mining activities have resulted in the excavation of two underground mines at the Vazante Operation, both of which are accessed by means of adits and ramps. The underground excavation for the Vazante Mine has achieved a depth of approximately 650 m from surface and provides access to approximately 5.3 km of the Vazante portion of the mineralized trend. The Extremo Norte Mine has achieved a depth of approximately 400 m from surface and provides access to approximately 1.6 km of the Extremo Norte portion of the mineralized trend. The two mines are separated by a distance of approximately 2.2 km (Figure 11-6).

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Figure 11-5:           Plan View of the Topographic Surfaces

 

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Figure 11-6: Plan and Longitudinal Views of the Underground Development

 

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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As mining has been on-going at the Vazante Operation since before the development of Cavity Monitoring Survey (CMS) equipment, little digital information is available regarding the shapes of many of the stopes that have been excavated over the long production history of the mine. Prior to the implementation of the CMS surveys at the Vazante Operation, the extent of the excavations for the level developments were determined by the traditional line-and-offset method. This historical survey information was subsequently used to prepare digital models of the excavated level developments.

 

Beginning in January 2018, Nexa has employed a Reigl Model Vz400 laser scanner to create digital models of all excavated level developments and excavated stopes (Figure 11-7 and Figure 11-8). As a result of this history, digital information is available for most of the excavated levels and ramps, but only partial digital information is available for the excavated stopes. The digital information used in preparation of the Mineral Resource estimate regarding the mining excavations is current as of October 31, 2020.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Figure 11-7:         Longitudinal View of the Mined Excavations, Vazante Mine

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

  

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Figure 11-8:          Longitudinal View of the Mined Excavations, Extremo Norte Mine

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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11.2.4 Resource Assays

   

The various mineralization wireframe models were used to code the drill hole database and identify the raw assay samples, or resource assays, that are contained within the mineralized wireframes. These samples were extracted from the database into their respective domains, and then subjected to statistical analyses by means of histograms and probability plots. A total of 36,235 zinc samples were contained within the primary, secondary, and tertiary mineralized wireframes for the Vazante deposit. A total of 9,674 zinc samples were contained within the primary, secondary, and tertiary mineralized wireframes for the Extremo Norte deposit. The resource assay sample statistics and the selected capping values for the uncapped assay values are summarized in Table 11-3. Selected histograms and probability plots are provided in Figure 11-9 to Figure 11-14.

 

Table 11-3:          Summary Of Uncapped, Clustered Raw Sample Statistics, Willemite Mineralization 

Nexa Resources S.A. – Vazante Polymetallic Operations

 

    Primary       Secondary       Tertiary  
Item      Zinc
(% Zn)
      Lead
(% Pb)
      Silver
(g/t Ag)
      Zinc
(% Zn)
      Lead
(% Pb)
      Silver
(g/t Ag)
      Zinc
(% Zn)
      Lead
(% Pb)
      Silver
(g/t Ag)
 
Vazante Deposit  
Mean     22.69       0.59       42.3       19.54       0.48       34.8       4.19       0.24       7.8  
Median     22.55       0.30       13.8       17.35       0.27       9.8       2.31       0.21       1.0  
Standard Deviation     14.42       0.97       108.6       13.00       0.74       106.6       7.11       0.24       80.7  
Coefficient of Variation     0.64       1.64       2.57       0.66       1.56       3.06       1.70       0.98       10.4  
Minimum     0.03       0.00       0.25       0.05       0.01       0.25       0.01       0.00       0.25  
Maximum     59.52       21.36       2,520       56.34       12.07       3,451       53.59       7.61       3,499  
Number of Samples     23,598       15,341       14,204       7,284       5,217       4,385       5,353       4,823       4,832  
Capping Value     54       8       1,000       50       5       850       48       2.5       250  
      Extremo Norte Deposit    

Mean     18.76       0.33       17.2       15.33       0.28       11.5       3.31       0.33       1.6  
Median     16.00       0.28       9.2       12.56       0.25       6.3       2.40       0.29       0.5  
Standard Deviation     12.92       0.35       48.0       10.40       0.26       22.5       4.18       0.26       4.5  
Coefficient of Variation     0.69       1.07       2.8       0.68       0.92       1.95       1.26       0.80       2.8  
Minimum     0.21       0.00       0.3       0.45       0.05       0.3       0.04       0.00       0.3  
Maximum     55.89       12.95       1,685       46.15       5.21       335.0       52.89       3.86       147.0  
Number of Samples     5,327       5,031       4,678       358       354       324       3,989       3,944       3,020  
Capping Value     50       3       560       42       1.5       100       48       2.5       35  

  

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000 

Technical Report Summary - February 15, 2021

  

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Source: Nexa

 

Figure 11-9:        Raw Assay Histogram and Probability Plots for Zinc Within the Primary Mineralized Wireframe, Vazante Deposit

    

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000 

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Source: Nexa

 

Figure 11-10:        Raw Assay Histogram and Probability Plots for Zinc Within the Secondary Mineralized Wireframe, Vazante Deposit

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Source: Nexa

 

Figure 11-11:          Raw Assay Histogram and Probability Plots for Zinc Within the Tertiary Mineralized Wireframe, Vazante Deposit

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Source: Nexa

 

Figure 11-12:       Raw Assay Histogram and Probability Plots for Zinc Within the Primary Mineralized Wireframe, Extremo Norte Deposit

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Source: Nexa

 

Figure 11-13:        Raw Assay Histogram and Probability Plots for Zinc Within the Secondary Mineralized Wireframe, Extremo Norte Deposit

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Source: Nexa

 

Figure 11-14:        Raw Assay Histogram and Probability Plots for Zinc Within the Secondary Mineralized Wireframe, Extremo Norte Deposit

 

11.2.5 Treatment of High Grade Assays

 

In order to reduce the influence of high grade sample values, a simple capping approach was applied. In this method, the grades of the resource assays contained within the respective mineralized wireframes that are deemed to represent anomalously high grades are reduced to a maximum value – the capping grade. A summary of the descriptive statistics for the capped, cell declustered sample populations for each of the mineralized wireframes is presented in Table 11-4.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

  

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Table 11-4:          Summary of Capped, Declustered Sample Statistics, Willemite Mineralization

Nexa Resources S.A. – Vazante Polymetallic Operations

  

    Primary       Secondary       Tertiary  
Item      Zinc
(% Zn)
      Lead
(% Pb)
      Silver
(g/t Ag)
      Zinc
(% Zn)
      Lead
(% Pb)
      Silver
(g/t Ag)
      Zinc
(% Zn)
      Lead
(% Pb)
      Silver
(g/t Ag)
 
Vazante Deposit  
Mean     20.21       0.50       37.1       17.67       0.44       29.5       4.30       0.24       6.3  
Median     18.55       0.27       11.6       14.90       0.26       9.5       2.48       0.21       1.2  
Standard Deviation     12.53       0.74       93.0       11.09       0.66       67.1       6.38       0.21       25.1  
Coefficient of Variation     0.62       1.49       2.51       0.63       1.51       2.3       1.48       0.88       3.8  
Minimum     0.10       0.00       0.3       0.05       0.01       0.3       0.01       0.01       0.3  
Maximum     54.00       8.00       1,000       50.0       5.00       850       48.00       2.50       250  
Extremo Norte Deposit  
Mean     16.49       0.29       12.7       13.98       0.27       10.0       3.18       0.31       1.7  
Median     13.70       0.24       5.7       11.52       0.25       5.2       2.47       0.28       0.6  
Standard Deviation     10.45       0.30       29.0       8.81       0.13       13.5       3.55       0.24       3.4  
Coefficient of Variation     0.63       1.03       2.3       0.63       0.48       1.3       1.12       0.75       2.2  
Minimum     0.36       0.00       0.3       1.46       0.07       0.3       0.04       0.00       0.3  
Maximum     50.00       3.00       560       41.23       0.99       100       48.00       2.50       35.0  

 

11.2.6 Compositing

 

The capped assay samples contained within the primary, secondary, and tertiary mineralized wireframes for the Vazante and Extremo Norte deposits were composted into equal sample lengths of one metre using the best-fit compositing method using the Datamine software package. SLR has examined the supporting data for the selection of this composite sample length and agrees that it is appropriate for this data set, style of mineralization, and the anticipated mining method. The descriptive statistics for the capped composite samples are provided in Table 11-5.

   

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Table 11-5:          Summary of Capped, Composite Sample Statistics, Willemite Mineralization

Nexa Resources S.A. – Vazante Polymetallic Operations

  

    Primary       Secondary       Tertiary  
Item      Zinc
(% Zn)
      Lead
(% Pb)
      Silver
(g/t Ag)
      Zinc
(% Zn)
      Lead
(% Pb)
      Silver
(g/t Ag)
      Zinc
(% Zn)
      Lead
(% Pb)
      Silver
(g/t Ag)
 
                                                                         
Vazante Deposit  
Mean     22.59       0.40       26.0       19.14       0.29       16.5       4.24       0.20       4.5  
Median     21.73       0.22       5.0       16.92       0.19       1.60       2.50       0.20       0.9  
Standard Deviation     13.29       0.72       69.9       11.64       0.51       53.9       6.59       0.19       16.9  
Coefficient of Variation     0.59       1.81       2.7       0.61       1.79       3.26       1.54       0.95       3.8  
Minimum     0.1       0.00       0       0.05       0.00       0       0.01       0       0  
Maximum     54       8.00       1,000       50       5.0       850       48       2.5       250  
Extremo Norte Deposit  
Mean     18.63       0.30       15.3       15.07       0.27       11.0       3.33       0.30       1.7  
Median     16.25       0.28       8.3       12.11       0.25       6.2       2.47       0.28       0.5  
Standard Deviation     11.90       0.22       29.8       9.32       0.19       14.6       3.99       0.22       3.3  
Coefficient of Variation     0.64       0.74       2.0       0.62       0.71       1.3       1.20       0.75       2.0  
Minimum     0.36       0.00       0.0       1.46       0.00       0.0       0.04       0.00       0.0  
Maximum     50       3.00       560.0       42.00       1.50       100       48       2.50       35.0  

 

11.2.7 Bulk Density

 

The relationship of the density values to the zinc, lead, and iron grades was carried out using the available density measurements contained within the mineralized wireframe volumes for the Vazante and Extremo Norte deposits (Figure 11-15 and Figure 11-16). The data clearly demonstrates that a consistent relationship is present that can be modelled using the following equation:

 

Bulk Density = 0.022657 x (Zn + Pb + Fe) + 2.785876

 

This formula was used to calculate the bulk density using the estimated zinc, lead, and iron grades for the Vazante and Extremo Norte deposits.

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

11-24

 

 

 

  

Figure 11-15:           Relationship of Measured Bulk Density with Zinc, Lead, and Iron Grades, Vazante Deposit

  

 

   

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Figure 11-16:           Relationship of Measured Bulk Density with Zinc, Lead, and Iron Grades, Extremo Norte Deposit

 

 

   

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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11.2.8  Trend Analysis

 

11.2.8.1 Grade Contouring

 

As an aid in conducting variography studies of the continuity of the zinc grades in the mineralized domain models, a short study to examine the overall trends was conducted. For this exercise, the distribution of zinc grades were examined using the mineralized wireframe models for the Vazante portion 2019 YE update of the Mineral Resources (Figure 11-17). The contoured data shows that the distribution of the zinc values is generally oriented in a horizontal to sub-horizontal direction along the strike length of the mineralization examined.

  

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Figure 11-17:          Contoured Zinc Grades, Vazante Deposit

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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11.2.8.2 Variography

  

Nexa began its analysis of the spatial continuity by constructing separate downhole and omni-directional variograms using the composite data for the zinc, lead, silver, and iron grades for each of the mineralized wireframes for the Vazante and Extremo Norte deposits, with the objective of determining an appropriate value for the global nugget (C0). The analysis then proceeded with the preparation of directional variograms to search for any anisotropies that may be present in the data, which resulted in successful variograms with good model fits (Figure 11-18 and Figure 11-19).

 

The GSLIB software package was used to calculate the variograms and charts of the results were prepared using Nexa’s in-house software. A summary of the variogram parameters derived for each of the mineralized wireframe models is presented in Table 11-6. The left hand rule was used as the rotation convention wherein the Y axis is the direction of maximum continuity (major axis), the X axis is the direction of the semi-major axis, and the Z axis is the direction of the minor axis.

 

 

 

Source: Nexa

 

Figure 11-18:      Example Variograms for Zinc Grades Contained Within the Primary Mineralized Wireframe Domain, Vazante Deposit

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Source: Nexa

 

Figure 11-19:      Example Variograms for Zinc Grades Contained Within the Primary Mineralized Wireframe Domain, Extremo Norte Deposit

 

Table 11-6:      Summary of Variogram Parameters, Willemite Mineralization
Nexa Resources S.A. – Vazante Polymetallic Operations

   

Domain     Item     Zinc       Lead       Silver       Iron  
Vazante Deposit  
      C0 Nugget     0.30       0.35       0.38       0.38  
      C1 1st structure     0.30       0.35       0.38       0.38  
      C2 2nd structure     0.25       0.20       0.20       0.14  
Primary     C3 3rd structure     0.15       0.10       0.04       0.13  
      A1 1st Range Z (m)     4       2       1       3  
      A2 2nd Range Z (m)     12       7       3       6  
      A3 3rd Range Z (m)     25       8       6       7  
      A1 1st Range X (m)     8       5       4       10  

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Domain   Item   Zinc   Lead   Silver   Iron
    A2 2nd Range X (m)     35   15   8   35
    A3 3rd Range X (m)     150   80   60   150
    A1 1st Range Y (m)     8   10   3   12
    A2 2nd Range Y (m)     35   30   10   150
    A3 3rd Range Y (m)     200   150   90   250
                       
  C0 Nugget     0.22   0.15   0.26   0.20
    C1 1st structure     0.36   0.45   0.40   0.40
    C2 2nd structure     0.25   0.33   0.25   0.35
    C3 3rd structure     0.17   0.07   0.09   0.05
    A1 1st Range Z (m)     3   2   1   2
    A2 2nd Range Z (m)     4   4.5   2.5   9
Secondary   A3 3rd Range Z (m)     5   5   7   10
    A1 1st Range X (m)     10   5   7   5
    A2 2nd Range X (m)     20   10   15   30
    A3 3rd Range X (m)     100   80   25   45
    A1 1st Range Y (m)     12   8   8   8
    A2 2nd Range Y (m)     30   20   13   20
    A3 3rd Range Y (m)     130   100   50   120
                       
  C0 Nugget     0.11   0.20   0.20   0.12
    C1 1st structure     0.30   0.35   0.35   0.40
    C2 2nd structure     0.30   0.30   0.30   0.30
    C3 3rd structure     0.29   0.15   0.15   0.18
                       
    A1 1st Range Z (m)     3   1   1.5   2
    A2 2nd Range Z (m)     9   4   4   4
Tertiary   A3 3rd Range Z (m)     12   9   7   8
    A1 1st Range X (m)     5   4   4   5
    A2 2nd Range X (m)     15   8   10   15
    A3 3rd Range X (m)     80   70   35   80
    A1 1st Range Y (m)     15   8   8   8
    A2 2nd Range Y (m)     40   15   20   20
    A3 3rd Range Y (m)     130   100   80   120

 

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Domain   Item   Zinc   Lead   Silver   Iron
                     
Extremo Norte Deposit
    C0 Nugget   0.32   0.10   0.15   0.25
    C1 1st structure   0.32   0.40   0.45   0.40
    C2 2nd structure   0.18   0.30   0.30   0.20
    C3 3rd structure   0.18   0.20   0.10   0.15
    A1 1st Range Z (m)   4.5   3   2   4
    A2 2nd Range Z (m)   6   4   3   5
Primary   A3 3rd Range Z (m)   7   5   6   6
    A1 1st Range X (m)   5   7   5   3
    A2 2nd Range X (m)   30   15   10   6
    A3 3rd Range X (m)   100   90   50   25
    A1 1st Range Y (m)   5   8   7   7
    A2 2nd Range Y (m)   30   40   35   25
    A3 3rd Range Y (m)   200   100   100   80
                     
    C0 Nugget   0.15   0.10   0.10   0.30
    C1 1st structure   0.36   0.45   0.40   0.40
    C2 2nd structure   0.30   0.25   0.25   0.20
    C3 3rd structure   0.19   0.20   0.25   0.10
    A1 1st Range Z (m)   3   5   4   4
    A2 2nd Range Z (m)   4   9   5   12
Secondary   A3 3rd Range Z (m)   8   10   6   15
    A1 1st Range X (m)   5   5   10   2
    A2 2nd Range X (m)   30   10   35   6
    A3 3rd Range X (m)   90   80   50   25
    A1 1st Range Y (m)   10   5   10   15
    A2 2nd Range Y (m)   25   50   15   25
    A3 3rd Range Y (m)   90   60   80   40
                     
    C0 Nugget   0.17   0.17   0.17   0.32
    C1 1st structure   0.30   0.35   0.33   0.35
Tertiary   C2 2nd structure   0.33   0.30   0.28   0.20
    C3 3rd structure   0.20   0.18   0.22   0.13

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Domain   Item   Zinc   Lead   Silver   Iron
    A1 1st Range Z (m)   2.5   3   4   4
    A2 2nd Range Z (m)   3   4   6   8
    A3 3rd Range Z (m)   6   8   8   12
  A1 1st Range X (m)   5   5   3   5
    A2 2nd Range X (m)   10   45   20   15
    A3 3rd Range X (m)   50   70   100   80
    A1 1st Range Y (m)   8   8   5   8
    A2 2nd Range Y (m)   20   15   10   20
    A3 3rd Range Y (m)   60   100   25   120

 

11.2.9 Block Model Construction

 

Two block models were constructed by Nexa using the Datamine software package and the mine grid coordinate system. The block models used a parent block size of 10 m (X) x 10 (Y) m x 5 m (Z) sized blocks and using sub-blocking with a minimum block size of 1 m (X) x 1 m (Y) x 0.5 m (Z). The block models are oriented parallel to the mine grid coordinate grid system (i.e., no rotation or tilt). The selection of the block sizes for this model remain unchanged from the block sizes that have been used for preparation of the previous Mineral Resource and Mineral Reserve estimates. The block model origin and dimensions are provided in Table 11-7. A number of attributes were created to store such information as rock code, material densities, estimated metal grades, final mineral resource classification, and the like (Table 11-8). The same list of attributes was used to populate both block models.

 

Table 11-7:      Block Model Definition, Vazante and Extremo Norte Deposits

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Type   Units   Y
(Northing)
  X
(Easting)
  Z
(Elevation)
                 
Vazante Deposit
Minimum Coordinates     m   11,447   767   -127
Maximum Coordinates     m   15,567   5,727   663
Parent Block Size     m   10   10   5
Sub-block Size     m   1   1   0.5
Rotation     °   0.000   0.000   0.000
Extremo Norte Deposit
Minimum Coordinates     m   15,331   5,327   59
Maximum Coordinates     m   19,511   8,167   739
Parent Block Size     m   10   10   5
Sub-block Size     m   1   1   0.5
Rotation     °   0.000   0.000   0.000

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Table 11-8:          List of Block Model Attributes, Vazante and Extremo Norte Deposits

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Attribute Name   Type     Decimals     Background     Description
ag     Real       0       0      
density     Real       0       -1e+30      
fe     Real       0       0      
kvarag     Real       0       -1e+30      
kvarfe     Real       0       -1e+30      
kvarpb     Real       0       -1e+30      
kvarzn     Real       0       -1e+30      
lito     Real       0       -1e+30     1=mineralized wireframe, 2=waste
nsamag     Real       0       -1e+30      
nsamfe     Real       0       -1e+30      
nsampb     Real       0       -1e+30      
nsamzn     Real       0       -1e+30      
ore     Real       0       0     1=primary, 2=secondary, 3=tertiary
pb     Real       0       0      
recovery     Real       0       -1e+30      
rectype     Real       0       -1e+30      
resource     Real       0       -1e+30      
surface     Real       0       -1e+30      
svol     Real       0       -1e+30      
svolag     Real       0       -1e+30      
svolfe     Real       0       -1e+30      
svolpb     Real       0       -1e+30      
svolzn     Real       0       -1e+30      
tonnes     Real       0       -1e+30      
trdip     Real       0       -1e+30      
trdipdir     Real       0       -1e+30      
trstkdip     Real       0       -1e+30      
trstkdir     Real       0       -1e+30      
zn     Real       0       0      

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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11.2.10 Search Strategy and Grade Interpolation Parameters

 

Metal grades were estimated into the blocks by means of the Ordinary Kriging (OK) interpolation algorithm. A total of three interpolation passes at different ranges were carried out for each of the mineralized wireframes using distances derived from the variogram results and the search ellipse parameters presented previously. All search ellipses adopted the dynamic search function of the Datamine software package in which the orientation of the search ellipse is varied so as to remain as parallel as possible to the local strikes and dips of the mineralization. An example of the search strategies and estimation parameters used to estimate the metal grades for the primary mineralization domain of the Vazante deposit is presented in Table 11-9.

 

In general, “hard” domain boundaries were used along the contacts of the mineralized domain models. Only data contained within the respective wireframe model was allowed to be used to estimate the grades of the blocks within the wireframe in question, and only those blocks within the wireframe limits were allowed to receive grade estimates.

 

Table 11-9:      Search Parameters and Estimation Strategies, Primary Mineralized Wireframe, Vazante Deposit

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Item   Zinc Lead   Silver   Iron
Interpolation method     OK   OK   OK   OK
Search volume method     Ellipsoid   Ellipsoid   Ellipsoid   Ellipsoid
Length of axis 1     150   80   60   150
Length of axis 2     200   150   90   250
Length of axis 3     25   8   6   7
First rotation angle     48   48   48   48
Second rotation angle     0   0   0   0
Third rotation angle     50   50   50   50
First rotation axis (1=X, 2=Y, 3=Z)     3   3   3   3
Second rotation axis (1=X, 2=Y, 3=Z)     1   1   1   1
Third rotation axis (1=X, 2=Y, 3=Z)     2   2   2   2
Octant Definition Method     Use Octants   Use Octants   Use Octants   Use Octants
Min. number of octants to be filled     2   2   2   2
Min. number of samples in an octant     1   1   1   1
Max. number of samples in an octant     40   40   40   40
Min. number of samples for first dynamic search volume     8   8   8   8
Max. number of samples for first dynamic search volume     30   30   30   30
Axis multiplying factor for second dynamic search volume     8   8   8   8
Min. number of samples for second dynamic search volume     8   8   8   8
Max. number of samples for second dynamic search volume     30   30   30   30
Axis multiplying factor for third dynamic search volume     3   3   3   3
Min. number of samples for third dynamic search volume     8   8   8   8
Max. number of samples for third dynamic search volume     30   30   30   30
Maximum multiplying factor     5   5   5   5

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Item   Zinc     Lead     Silver     Iron  
Min. number of samples for second
dynamic search volume
    8       8       8       8  
                                 
Max. number of samples for second
dynamic search volume
    30       30       30       30  
                                 
Axis multiplying factor for third dynamic
search volume
    3       3       3       3  
                                 
Min. number of samples for third dynamic
search volume
    8       8       8       8  
                                 
Max. number of samples for third dynamic
search volume
    30       30       30       30  
                                 
Maximum multiplying factor     5       5       5       5  

 

11.2.11 Block Model Validation

 

Block model validation exercises included several validation techniques that included examination of the global mean grades, preparation of swath plots, Quantile-Quantile (Q-Q) plots, scatter plots, histogram comparison, and visual validation.

 

11.2.11.1 Global Estimate

 

Block model validation exercises consisted of visually comparing the volume of the coded blocks in the block model against the volume report of the respective wireframe models as a high level check that the block model has been correctly coded for each of the wireframes. No issues were noted.

 

A comparison of the average grades of the informing capped, declustered composite samples against the average estimated block grades was carried out (Table 11-10).

 

Table 11-10:        Comparison of Composite Sample Grades with Estimated Block Model Grades, Willemite 

Nexa Resources S.A. – Vazante Polymetallic Operations

  

      Primary       Secondary       Tertiary  
Item      Zinc
(% Zn)
      Lead
(% Pb)
      Silver
(g/t Ag)
      Zinc
(% Zn)
      Lead
(% Pb)
      Silver
(g/t Ag)
      Zinc
(% Zn)
      Lead
(% Pb)
      Silver
(g/t Ag)
 
                      Vazante Deposit                            
Composite Mean     22.59       0.40       26.0       19.14       0.29       16.5       4.24       0.20       4.5  
Block Model Average     19.65       0.53       36.8       18.81       0.48       31.3       3.84       0.26       5.7  
Difference (Bm-Comp)     -2.94       +0.13       +10.8       -0.33       +0.19       +14.8       -0.4       +0.06       +1.2  
% Difference (vs Comp)     -13 %     +33%       +42%       -2 %     +66%       +90%       -9 %     +30%       +27%  
Extremo Norte Deposit  
Composite Mean     18.63       0.30       15.3       15.07       0.27       11.0       3.33       0.30       1.7  
Block Model Average     18.08       0.31       16.3       15.86       0.29       12.8       5.89       0.55       1.5  
Difference (Bm-Comp)     -0.55       +0.01       +1.0       +0.79       +0.02       +1.8       +2.56       +0.25       -0.2  
% Difference (vs Comp)     -3 %     +3%       +7%       +5%       +7%       +16%       +77%       +83%       -12 %

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

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Review of the results shows that the estimated zinc grades are in reasonable agreement with the informing samples for the primary and secondary mineralized wireframes at the Vazante and Extremo Norte deposits. A high variance, however, is observed in the estimated zinc grades for the tertiary mineralized wireframe for the Extremo Norte deposit. While high variances are observed for the estimated lead and silver grades for the secondary and tertiary mineralized wireframes, it is important to note that these metals provide only a minor contribution to the overall value of the mineralization.

 

11.2.11.2 Swath Plots

 

Nexa conducted an evaluation of the spatial accuracy of the estimated grades by constructing a series of swath plots that compared the average composite grades to the average estimated block model grades in plan, section, and longitudinal orientations. Sample swath plots for selected wireframes are presented in Figure 11-20 and Figure 11-21. Review of the swath plots show a reasonable agreement between the estimated grades and their respective informing composite samples.

 

11.2.11.3 Quantile-Quantile Plots

 

The accuracy of the distribution of the zinc grades between the informing composite samples and the estimated block grades was examined by construction of Q-Q plots using the GSLIB software package (Figure 11-22 and Figure 11-23). Very good agreement is observed in the distribution between the estimated zinc grades and the corresponding informing samples for the primary and secondary mineralized wireframes at the Vazante and the Extremo Norte deposits. Similarly, very good agreement is observed in the distribution between the estimated zinc grades and the corresponding informing samples for the tertiary mineralized wireframe at the Vazante deposit. A slight bias in favour of the informing samples (i.e. block grades are under-estimated) is observed for the tertiary mineralized wireframe at the Extremo Norte deposit for zinc grades above approximately 8% Zn.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Figure 11-20:       Swath Plots for Zinc, Primary Mineralized Wireframes, Vazante Deposit

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Figure 11-21:    Swath Plots for Zinc, Primary Mineralized Wireframes, Extremo Norte Deposit

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Figure 11-22:      Quantile-Quantile Plots of the Zinc Grades, Vazante Deposit

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Figure 11-23:      Quantile-Quantile Plots of the Zinc Grades, Extremo Norte Deposit

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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11.2.11.4 Scatter Plots

 

The accuracy of the distribution of the zinc grades between the informing composite samples and the estimated block grades was also examined by construction of simple scatter plots using the GSLIB software package (Figure 11-24 and Figure 11-25). The results show that a good agreement is present between the estimated zinc grades and their corresponding informing samples for the primary and secondary mineralized wireframes for the Vazante and Extremo Norte deposits. Higher variances are observed for the tertiary mineralized wireframes, however.

 

 

  

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Figure 11-24:      Scatter Plots of the Zinc Grades, Vazante Deposit

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Figure 11-25:       Scatter Plots of the Zinc Grades, Extremo Norte Deposit

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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11.2.11.5 Histogram Comparison

 

The accuracy of the distribution of the zinc grades between the informing composite samples and the estimated block grades was also examined by construction of normal scores histograms and the results charted using the Microsoft (MS) Excel software package (Figure 11-26 and Figure 11-27). Good agreements are observed in the grade distributions of the estimated zinc grades and their corresponding informing samples.

 

In SLR’s opinion, the validation performed by Nexa and SLR are typical industry standard validation techniques and in general, the results presented suggest that the block model has been completed to a high standard, in line with industry best practices.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

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Figure 11-26:     Normal Scores Histogram Plots of the Zinc Grades, Vazante Deposit

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Figure 11-27:      Normal Scores Histogram Plots of the Zinc Grades, Extremo Norte Deposit

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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11.2.12 Mineral Resource Classification

 

Definitions for Mineral Resource categories used in this Technical Report Summary are those defined by SEC in S-K 1300. Mineral Resources are classified into Measured, Indicated, and Inferred categories

 

Mineralized material for each wireframe was initially classified into the Measured, Indicated, or Inferred Mineral Resource categories on the basis of the density of drill hole and chip sample information, and presence of underground access as follows:

 

Mineral Resource Category Sample Spacing
Measured 25 m x 15 m
Indicated 50 m x 30 m
Inferred 100 m x 60 m
Potential >100 m x 100 m, or lenses based on a single drill hole

 

In addition to the Measured, Indicated, and Inferred categories, Nexa adopts an additional category for classification of mineralized material. This fourth classification category is termed “Potential” and is used strictly for exploration and planning purposes. No quantities of mineralized material classified into the Potential category form part of either the Mineral Resource or Mineral Reserve statements.

 

Following the classification of the mineralized material into the initial Mineral Resource categories, clipping polygons were used in a final stage of the process to edit the initial classification assignments so as to ensure continuity and consistency of the final classified blocks in the model (Figure 11-28 and Figure 11-29).

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Figure 11-28:        View of the Final Mineral Resource Classification, Primary Mineralized Wireframe, Vazante Deposit

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Figure 11-29:        View of the Final Mineral Resource Classification, Primary Mineralized Wireframe, Extremo Norte Deposit

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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11.2.13 Net Smelter Return and Cut-Off Grade Parameters

 

An NSR cut-off value was determined using the Mineral Resource metal prices, metal recoveries, transport, treatment, and refining costs, as well as mine operating cost. Metal prices used for Mineral Resources are based on consensus, long term forecasts from banks, financial institutions, and other sources. All domestic costs were converted to an equivalent US dollar basis using an average long term exchange rate of R$4.84/US$.

 

The cut-off value used for the Mineral Resource estimate is based on an NSR value, in units of US$/t, which can be directly compared to operating unit costs. The NSR formula is:

 

 

Cut-off costs and NSR parameters are summarized in Table 11-11. The break even NSR cut-off value for SLS and Room and Pillar (R&P) mining methods are $47.49/t processed and $74.96/t processed, respectively.

 

Table 11-11: Resource NSR Data- Willemite Mineralization

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Item   Units   SLS     R&P  
Metallurgical Recovery                    
Zn   %     83.56       83.56  
Pb   %     22.05       22.05  
Ag   %     42.00       42.00  
Metal Payability                    
Zn Concentrate Payable                    
Zn   %     94.4       94.4  
Pb Concentrate Payable         95.0       95.0  
Pb   Min Payable/Deduction     95%/3%     95%/3%
Ag   Min Payable/Deduction     95%/50.0 g/t       95%/50.0 g/t  
Metal Prices                    
Zn   US$/lb     1.30       1.30  
Pb   US$/lb     1.02       1.02  
Ag   US$/oz     19.38       19.38  
Transport Charges                    
Zn Concentrate   US$/t conc.     16.60       16.60  
Pb Concentrate   US$/t conc.     278.72       278.72  
Treatment Charges                    
Pb Concentrate   US$/t conc.     142.57       142.57  
Refining Charges                    
Ag in Pb Concentrate   US$/oz     1.00       1.00  
Integrated Zn
(processed at Três Marias)
                   
Premium   US$/t     286.31       286.31  
Conversion Cost   US$/t     473.95       473.95  
Operating Costs                    
Mining   US$/t proc.     27.47       54.94  
Processing   US$/t proc.     14.57       14.57  
G&A   US$/t proc.     5.45       5.45  
Total   US$/t proc.     47.49       74.96  

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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NSR calculations use a model head grade-recovery relationship for each metal, based on recent operating performance. The head grade and recovery curves are presented in Figure 11-30 and Figure 11-31. NSR factors are therefore variable by head grade, with average NSR factors summarized in Table 11-12. The average NSR factors are calculated using the LOM revenue contribution from each metal net of off-site costs and factors, divided by the reserve grade for that metal, and are indicative of the relative contribution of each metal unit to the economics of the mine. For most metals, a variable recovery (as a function of head grade) was used, and therefore the average NSR factors should not be applied to head grades without considering the head grade versus recovery relationship.

 

 

Figure 11-30:    Zinc Grade-Recovery Curve for the Willemite Mineralization

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000 

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Figure 11-31:      Lead Grade-Recovery Curve for the Willemite Mineralization

 

Table 11-12:      Average NSR Factors For the Willemite Mineralization

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Item     Units   Value  
  Zn     US$/% Zn     19.61  
  Pb     US$/% Pb     1.04  
  Ag     US$/oz Ag     6.88  

 

Metal prices are based on Nexa’s projections. Nexa’s long term price model uses multiple variables including supply (mine and refined), demand, cost drivers, capital cost, and other key elements. The long term prices derived are in line with the consensus forecasts from banks and independent institutions.

 

11.2.14 Mineral Resource Reporting

 

Definitions for Mineral Resource categories used in this Technical Report Summary are those defined by SEC in S-K 1300. Mineral Resources are classified into Measured, Indicated, and Inferred categories.

 

The Mineral Resources are exclusive of Mineral Reserves. The Mineral Resources are located as remnants in proximity of the existing underground excavations or as additional mineralized areas located beyond or below the current underground development. Three-dimensional reporting volumes were prepared to aid in the reporting of the Mineral Resources to ensure that the “Reasonable Prospects” requirement of S-K 1300 was met. These reporting volumes were prepared using the native functions and workflows available through the Deswik mine modelling software package.

 

 

 

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The reporting volumes were created using similar parameters to those used to prepare the reporting volumes used for the reporting of Mineral Reserves. A minimum width of three metres was applied when creating the reporting panels for the Mineral Resources. Additional criteria included consideration of the envisioned mining method (SLS or room and pillar), exclusions for sill pillars in areas of either existing level development or planned future level development, crown pillars for those portions of the mineralization that are located close to the topographic surface, and geotechnical reservations.

 

As the Mineral Resources are stated exclusive of Mineral Reserves, only those reporting panels that were not used to prepare the Mineral Reserve statements were considered for preparation of the Mineral Resource statement. The reporting panels used to prepare the Vazante Operation hypogene Mineral Resource statements are presented in Figure 11-32 and Figure 11-33. The Vazante Operation hypogene Mineral Resources are summarized in Table 11-13. A summary of the previous Mineral Resources as of December 31, 2019 is presented in Table 11-14 for comparison purposes (Nexa, 2020d).

 

In SLR’s opinion, the assumptions, parameters, and methodology used for the Vazante Operation hypogene Mineral Resource estimates are appropriate for the style of mineralization and anticipated mining methods.

 

The SLR QP is of the opinion that, with consideration of the recommendations summarized in Sections 1 and 23, any issues relating to all relevant technical and economic factors likely to influence the prospect of economic extraction can be resolved with further work.

 

 

 

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Figure 11-32:        View of the Mineral Resource Reporting Panels, Vazante Deposit

 

 

 

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Figure 11-33:       View of the Mineral Resource Reporting Panels, Extremo Norte Deposit

 

 

 

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Table 11-13:           Mineral Resources for the Vazante and Extremo Norte Mineralization as of
December 31, 2020

Nexa Resources S.A. – Vazante Polymetallic Operations

 

    Tonnes     Grade     Contained Metal  
Category   (000t)     (% Zn)     (% Pb)     (g/t Ag)     (000 t Zn)     (000 t Pb)     (000 oz Ag)  
Measured     3,400       6.91       0.18       8.4       235       6.19       918  
Indicated     2,000       5.84       0.13       7.6       117       2.56       489  
Subtotal, M&I     5,400       6.51       0.16       8.1       352       8.75       1,408  
                                                         
Inferred     9,040       7.79       0.17       11.0       704       14.90       3,190  

 

Notes:

 

1. The definitions for Mineral Resources in S-K 1300 were followed for Mineral Resources which are consistent with CIM (2014) definitions.

 

2. Mineral Resources are reported on a 100% ownership basis.

 

3. Mineral Resources are estimated at a NSR cut-off value of US$47.49/t for SLS and US$74.96/t for R&P.

 

4. Mineral Resources are estimated using average long term metal prices of Zn: US$2,869.14/t (US$1.30/lb), Pb: US$2,249.40/t (US$1.02/lb), and Ag: US$19.38/oz, and metallurgical recoveries are based on recovery curves derived from historical processing data. An average long term R$/US$ exchange rate of 4.84 was used.

 

5. A minimum mining width of 3.0 m was used to create Mineral Resource reporting shapes.

 

6. Bulk density varies depending on the abundance of willemite and galena.

 

7. Mineral Resources are exclusive of Mineral Reserves.

 

8. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability.

 

9. Mineral Resources are reported for all material contained within reporting panels that have been created so as to achieve the required spatial continuity, cut-off grade, and minimum width criteria.

 

10. Numbers may not add due to rounding.

 

Table 11-14:           Summary of Previous Mineral Resources as of December 31, 2019 

Nexa Resources S.A. – Vazante Polymetallic Operations

 

    Tonnes     Grade     Contained Metal  
Category   (Mt)     (% Zn)     (% Pb)     (g/t Ag)     (000 t Zn)     (000 t Pb)     (000 oz Ag)  
Measured     2.37       10.38       0.31       12.9       246.0       7.3       981  
Indicated     1.57       8.81       0.26       11.0       138.3       4.1       554  
Subtotal, M&I     3.94       9.75       0.29       12.1       384.3       11.4       1,535  
                                                         
Inferred     9.46       8.55       0.22       12.2       808.8       20.8       3,720  

 

Notes:

 

1. The qualified person for the mineral resources estimate is José Antonio Lopes, B.Geo, MAusIMM (CP) Geo, a Nexa Resources employee.

 

2. Mineral resources are reported within underground mining shapes with minimum mining widths of 3 m.

 

3. Density was assigned based on rock type.

 

4. The NSR cut-offs are calculated based on the LOM costs independent of the mining method: SLS, VRM and C&F: US$63.28.

 

5. Forecast long term metal prices used for the NSR calculation are: Zn: US$2,899.15/t (US$1.31/lb); Pb: US$2,304/t (US$1.04/lb) and Ag: US$19.31/oz.

 

 

 

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11.2.15 Risks and Uncertainties to Mineral Resources

 

Based on SLR’s review of the Vazante and Extremo Norte Mineral Resource estimate, the following key risks have been identified:

 

· Due to the natural variability inherent to the willemite mineralization, the presence, location, size, shape, and grade of the actual mineralization between the existing sample points may differ from the current interpretation. The level of uncertainty in these items is lowest for the Measured Mineral Resource category and is highest for the Inferred Mineral Resource category. Nexa mitigates this uncertainty by implementation of its grade control programs.

 

· Due to the reliance of the estimation of the density on the estimate of metal grades for those portions of the mineralization not currently sampled, the tonnage for those portions can vary if the actual metal grades differ from the estimated metal grades. The density estimates can be improved with increased density of drill hole and channel sample data.

 

· Due to variations in the global supply chain, the actual metal prices realized at the time of production may differ from the long term metal prices that were used in the preparation of the Mineral Resource statements. Lower zinc metal prices realized at the time of production may result in a decrease in Mineral Resources. In SLR’s opinion the Mineral Resources are not sensitive to variations in the prices of silver or lead from those used in the current Mineral Resource statement.

 

· The cut-off grade (or value) used in preparation of the current Mineral Resource statement can be affected by variations in the Brazilian Real and United States dollar exchange rate. A strengthening of the Brazilian Real versus the United States dollar may result in an increase in the cut-off grade (or value), with a corresponding decrease in the Mineral Resources.

 

11.3 Supergene Mineralization (Calamine)

 

11.3.1 Resource Database

 

Information collected from surface-based drilling, underground-based drilling, and channel samples collected from the grade control program are all entered into a FusionTM master database that is used for database management at the Vazante Operation. The Fusion™ database was implemented in 2017. All data stored in the Vazante Operation database are verified using various software verification routines before final entry into the database. Nexa’s internal corporate standard operating procedure PO-VM-GRM-001, requires additional checking of the following items:

 

· Sample length problems

 

· Maximum and minimum grade values

 

· Negative values

 

· Detection limits and null values

 

· Drill hole surveys

 

· Sample size

 

· Gaps

 

 

 

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· Overlaps

 

· Drill hole collars versus topography coordinate datum

 

· Verification of mining permissions

 

· Laboratory analysis certificates.

 

Each of these items are checked and if discrepancies are discovered, verified, and corrected, as necessary.

 

Drill hole information for the supergene mineralization was extracted from the Fusion™ database into separate files for use in preparation of the Mineral Resource estimates. This drill hole information was modified slightly so as to be compatible with the format requirements of the Datamine and Leapfrog modelling packages and were imported into those software package by Nexa. A number of new tables and variables were created during the estimation process to capture such information as the interpreted mineralized intersection length along the drill holes, density readings, capped assay values, and composite values. No grade control samples or blast hole samples taken during the previous operation of the open pit mine are included in this drill hole sub-set.

 

The cut-off date for the assays in the supergene drill hole database is April 30, 2020. Drilling and sampling were carried out using the UTM Datum Cόrrego Alegre, Zone 23S grid coordinate system. The northing and easting collar coordinates of the drill holes and channel samples used to prepare the Mineral Resource estimate for the supergene mineralization remained in the UTM coordinate system. This is in contrast to the drill hole and channel sample information used to estimate the hypogene mineralization that has been converted to the mine grid coordinate system.

 

SLR recommends that the drill hole data relating to the supergene mineralization be converted into the mine grid coordinate system to more easily integrate the information for the underground mine.

 

A summary of the drilling information is provided in Table 11-15. Three areas of supergene mineralization were modelled: Cava 3A, Mata dos Paulistas, and Braquiara. All three areas are located generally along the northeastern most portion of the mineralized trend. The Cava 3A area comprises the area including and adjacent to the Extremo Norte open pit mine (Figure 11-34).

 

Table 11-15:       Summary of Drill Hole Database, Calamine Mineralization

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Data Type   Number of Records
Collar   414
Down hole survey   9,932
Lithology   5,484
Assays   23,239
Weathering   9,251
Composites (within mineralized
wireframe boundaries)
  3,131
Density   4,908

 

 

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11.3.2 Geology and Mineralization Interpretations

 

11.3.2.1 Geological Interpretations

 

Preparation of the geological interpretation began with construction of digital models by Nexa of the main un-weathered host rock units present at the Vazante Operation using the Leapfrog software package. This geological interpretation was carried out in the UTM coordinate system and adopted all available geological information such as surface mapping, surface-based and underground-based drilling information, and detailed mapping information collected as part of the grade control programs in the open pit and underground mines (Figure 11-35).

 

Interpretation activities then proceeded with consideration of the weathering profile that is present. Three weathering surfaces were created using the Leapfrog software package to represent the top of the unweathered rock, a transitional zone representing partially weathered rock, and a soil interval representing fully weathered material (Figure 11-36).

 

 

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Figure 11-34:         Drill Hole Locations, Calamine Mineralization

 

 

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Figure 11-35:       Inclined View of the Lithology Model (Overburden Removed), Calamine Mineralization

 

 

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Figure 11-36:        Sample Cross Section of the Lithology and Weathering Models, Calamine Mineralization

 

 

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11.3.2.2 Mineralization Wireframes

 

The mineralized wireframe interpretations were prepared by creating a series of grade shells at a nominal cut-off grade of 3% Zn using the Leapfrog software package. In general, these interpretations considered only those zinc grades above the nominated cut-off grade that were located in either the transition or soil portions of the weathering profile. The supergene zinc mineralization at the Vazante Mine has been traced intermittently by drilling along a strike length of approximately 4.3 km (Figure 11-37). A sample cross section of the mineralization wireframes is provided in Section 7.2 of this Technical Report Summary.

 

While lead and silver also form part of the hypogene mineralization found at the Vazante Mine, their contributions to the overall value of the mineralization are relatively minor in comparison with the revenue that is achieved from the zinc content (Figure 11-38). Consequently, the cut-off grade used to prepare the mineralized wireframe interpretations is based on a simple zinc only basis.

 

11.3.3 Topography and Excavation Models

 

The topographic surface used in preparation of the supergene Mineral Resources is constructed by the Nexa mine staff using various detailed surveying methods such as drone based LIDAR topography measurements or total station survey equipment. This topographic surface has an effective date of April 24, 2019 and provides information relating to the open pit excavations that have taken place for the Extremo Norte portion of the mineralized trend.

 

A portion of the open pit mine at the Extremo Norte deposit has been used to store backfill material derived from various sources at the Vazante Operation, consequently the current topographic surface does not represent the full extent of the open pit mine. A digital model of this backfill material was prepared by Nexa using the maximum extents of the open pit mine as the lower contact, and the current topographic surface as the upper contact (Figure 11-39).

 

 

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Figure 11-37:       View of the Mineralized Wireframe Outlines, Calamine Mineralization

 

 

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Figure 11-38:         Relative Value by Metal, Calamine Mineralization

 

 

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Figure 11-39:       Plan View of the Topographic Surface, Supergene Mineralization

 

 

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11.3.4 Resource Assays

 

The various mineralization wireframe models were used to code the drill hole database and identify the raw assay samples, or resource assays, that are contained within the mineralized wireframes. These samples were extracted from the database and then subjected to statistical analyses by means of histograms and probability plots. A total of 3,284 zinc samples were contained within the mineralized wireframes for the supergene mineralization. The resource assay sample statistics and the selected capping values for the uncapped assay values are summarized in Table 11-16. Selected histograms and probability plots are provided in Figure 11-40.

 

Table 11-16:      Summary of Uncapped, Clustered Raw Sample Statistics, Calamine Mineralization

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Item   Zinc
(% Zn)
    Lead
(% Pb)
    Silver
(g/t Ag)
 
Mean     10.95       0.18       1.31  
Median     7.39       0.10       0.68  
Standard Deviation     10.17       0.26       4.57  
Coefficient of Variation     0.93       1.48       3.50  
Minimum     0.00       0.00       0.02  
Maximum     51.06       3.87       117.0  
Number of Samples     3,284       3,284       3,284  
Capping Value     45.00       1.00       40.0  

 

11.3.5 Treatment of High Grade Assays

 

In order to reduce the influence of high grade sample values, a simple capping approach was applied. In this method, the grades of the resource assays contained within the respective mineralized wireframes that are deemed to represent anomalously high grades are reduced to a maximum value – the capping grade. A summary of the descriptive statistics for the capped, cell declustered sample populations for each of the mineralized wireframes is presented in Table 11-17.

 

 

 

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Source: Nexa

 

Figure 11-40:      Raw Assay Histogram and Probability Plots for Zinc Within the Calamine Mineralized Wireframes

 

Table 11-17:      Summary of Capped, Declustered Sample Statistics, Calamine Mineralization
Nexa Resources S.A. – Vazante Polymetallic Operations

 

Item   Zinc
(% Zn)
    Lead
(% Pb)
    Silver
(g/t Ag)
 
Mean     10.17       0.14       1.2  
Median     6.39       0.08       0.7  
Standard Deviation     9.55       0.17       3.1  
Coefficient of Variation     0.94       1.23       2.5  
Minimum     0.00       0.00       0.02  
Maximum     45.00       1.00       40.0  

 

 

 

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11.3.6 Compositing

 

The distribution of the capped assay samples contained within the supergene mineralized wireframes were examined by means of a simple histogram as an aid in the selection of an appropriate composite length (Figure 11-41). The results of this histogram show that a composite length of one metre is appropriate for this data set. All samples were composted into equal sample lengths of one metre using the best-fit compositing method in the Datamine software package. The descriptive statistics for the capped composite samples are provided in Table 11-18.

 

 

Source: Nexa

 

Figure 11-41:      Histogram of Sample Lengths Within the Calamine Mineralized Wireframes

 

Table 11-18:      Summary of Capped, Composite Sample Statistics, Calamine Mineralization

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Item   Zinc
(% Zn)
    Lead
(% Pb)
    Silver
(g/t Ag)
 
Mean     10.93       0.17       1.2  
Median     7.57       0.10       0.7  
Standard Deviation     9.80       0.20       2.7  
Coefficient of Variation     0.90       1.17       2.2  
Minimum     0.00       0.00       0.0  
Maximum     45.00       1.00       40.0  

 

 

 

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11.3.7 Bulk Density

 

As described previously, the supergene mineralized zones found at the Vazante Operation comprise a variety of host rock and material types ranging from fully weathered material through to fresh, un-weathered host rock units (Figure 11-42). The bulk densities of these various material types were determined by Nexa staff during the drilling programs. The procedure used to measure the densities of these materials included enveloping the sample in a plastic polyethylene film so as to provide a seal for porous and unconsolidated samples. The Jolly method was then used to determine the bulk density. In this method the samples are placed into a mesh bag and their dry weights are determined in air. The entire mesh bag is then submerged into a water bath and the weights of the samples are measured a second time. Nexa accounted for the weight and density of the plastic polyethylene film using the following formula:

 

D = PS / {PS- [PAR- (PRS/DR)]},

 

Where:

 

PS = dry weight of the sample,

 

PAR = enveloped sample weight in water,

 

PRS = dry envelope weight, and

 

DR = envelope density.

 

The bulk densities for a total of 2,054 samples were determined using representative samples taken during completion of the supergene drilling programs. The bulk density measurements for each material type were then extracted and evaluated to determine their average bulk densities.

 

Considering the limited number of bulk density measurements that have been completed and the high degree of variability inherent in these material types, insufficient bulk density measurements are available to estimate the bulk densities into the block model by means of a formula. Consequently, the average bulk densities for each of the mineralized wireframes were applied to the various material types coded in the block model.

 

A summary of the average supergene mineralization bulk densities used for the current Mineral Resource estimate is presented in Table 11-19.

 

 

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Figure 11-42: Examples of Mineralization Styles and Material Types, Supergene Mineralization

 

 

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Table 11-19:      Summary of Bulk Density Measurements, Supergene Mineralization

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Material   Average Bulk Density
(t/m3)
    Number of
Measurements
 
Overburden – (Non-mineralized)     1.50       58  
Weathered Calamine Mineralization (ARG)     1.50       113  
Massive Calamine Mineralization (MAC)     2.50       62  
Calamine Mineralization in Marl (MGA)     2.25       73  
Willemite Mineralization (WIL)     3.40       16  
Dolomite (Fresh, non-mineralized)     2.80       1,318  
Marl (Fresh, non-mineralized)     2.69       337  
Hydrothermal Breccia (Fresh rock)     2.87       38  

 

11.3.8 Trend Analysis

 

11.3.8.1 Variography

 

Nexa began its analysis of the spatial continuity by constructing separate downhole and omni-directional variograms using the composite data for the zinc, lead, and silver grades for the supergene mineralized wireframes, with the objective of determining an appropriate value for the global nugget (C0) (Figure 11-43). The analysis then proceeded with the preparation of directional variograms to search for any anisotropies that may be present in the data, which resulted in variograms with poor model fits. In SLR’s opinion, the inability to create successful variogram models is anticipated result considering the relatively small size of each of the mineralized wireframe models and their limited spatial continuity.

 

The GSLIB software package was used to calculate the variograms and charts of the results were prepared using Nexa’s in-house software. The left hand rule was used as the rotation convention wherein the Y axis is the direction of maximum continuity (major axis), the X axis is the direction of the semi-major axis and the Z axis is the direction of the minor axis. A summary of the variogram parameters is presented in Table 11-20.

 

 

 

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Source: Nexa

 

Figure 11-43:      Omni Directional Variogram, Zinc, Supergene Mineralization

 

Table 11-20:      Summary of Variogram Parameters, Supergene Mineralization
Nexa Resources S.A. – Vazante Polymetallic Operations

 

Item   Zinc     Lead     Silver  
C0 Nugget     0.10       0.10       0.10  
C1 1st structure     0.45       0.45       0.45  
C2 2nd structure     0.30       0.30       0.30  
C3 3rd structure     0.15       0.15       0.15  
A1 1st Range Z (m)     5       5       5  
A2 2nd Range Z (m)     12       12       12  
A3 3rd Range Z (m)     30       30       30  
A1 1st Range X (m)     5       5       5  
A2 2nd Range X (m)     12       12       12  
A3 3rd Range X (m)     30       30       30  
A1 1st Range Y (m)     5       5       5  
A2 2nd Range Y (m)     12       12       12  
A3 3rd Range Y (m)     30       30       30  

 

11.3.9 Block Model Construction

 

An initial block model was constructed by Nexa using the Datamine software package and the UTM coordinate system. The block model used a parent block size of 10 m (X) x 10 (Y) m x 5 m (Z) sized blocks and using sub-blocking with a minimum block size of 0.5 m (X) x 0.5 m (Y) x 0.5 m (Z). The block models are oriented parallel to the UTM grid coordinate grid system (i.e., no rotation or tilt). The block model origin and dimensions are provided in Table 11-21. A number of attributes were created to store such information as rock code, material densities, estimated metal grades, final mineral resource classification, and the like (Table 11-22).

 

 

 

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Table 11-21:      Initial Block Model Definition, Supergene Mineralization

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Type   Units     Y
(Northing)
    X
(Easting)
    Z
(Elevation)
 
Minimum Coordinates     m       8,014,100       304,911       533  
Maximum Coordinates     m       8,017,710       308,051       758  
Parent Block Size     m       10       10       5  
Sub-block Size     m       0.5       0.5       0.5  
Rotation     °       0.000       0.000       0.000  

 

Table 11-22:      List of Initial Block Model Attributes, Calamine Mineralization

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Attribute Name   Type     Decimals     Default     Description
ag     Real       0       -1e+30     Silver in g/t
density     Real       0       -1e+30      
fe     Real       0       -1e+30     Iron in %
kvar     Real       0       -1e+30     Kriging variance
lito     Real       0       -1e+30     1=overburden, 2=dolomite, 3=marl
nsam     Real       0       -1e+30     Number of samples
ore     Real       0       0     0=waste, 1=mineralized
orebody     Real       0       -1e+30     0=waste, 999=backfill, 910=void, wireframe number (1 to 25)
oretype     Real       0       -1e+30     1=argillite, 2=massive, 3=marl, 4=willemite
pb     Real       0       -1e+30     Lead in %
rectype     Real       0       -1e+30     0=waste, 1=remnant
resource     Real       0       -1e+30     2=indicated, 3=inferred
s     Real       0       -1e+30     Sulphur in %
svol     Real       0       -1e+30     Estimation domain
tonnes     Real       0       -1e+30      
weather     Real       0       -1e+30     1=soil, 2=transition, 3=rock
zn     Real       0       -1e+30     Zinc in %

 

 

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In preparation to create an optimized pit surface for use reporting of the Mineral Resources, the initial block model was subsequently re-blocked to blocks of equal size that measured 5 m x 5 m x 5 m in size. A number of attributes were also added to permit the calculation of a NSR value. The revised attribute list is shown in Table 11-23.

 

Table 11-23:      List Of Re-Blocked Block Model Attributes, Supergene Mineralization

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Attribute Name   Type     Decimals     Default     Description
ag     Real       0       -1e+30      
ag_ppm     Real       0       0      
au     Real       0       0      
cu     Real       0       0      
density     Real       0       -1e+30      
fe     Real       0       -1e+30      
lito     Real       0       -1e+30     1=overburden, 2=dolomite, 3=marl
nsr20rec     Real       0       0      
nsragres     Real       0       0      
nsraures     Real       0       0      
nsrcures     Real       0       0      
nsrpbres     Real       0       0      
nsrznres     Real       0       0      
ore     Real       0       0      
orebody     Real       0       -1e+30     Wireframe number
oretype     Real       0       -1e+30      
pb     Real       0       -1e+30      
rectype     Real       0       -1e+30      
resource     Real       0       -1e+30     2=indicated, 3=inferred
rock     Real       0       0      
s     Real       0       -1e+30      
slope     Real       0       0      
weather     Real       0       -1e+30     1=soil, 2=transition, 3=rock
zn     Real       0       -1e+30      

 

11.3.10 Search Strategy and Grade Interpolation Parameters

 

Metal grades were estimated into the blocks by means of the OK interpolation algorithm. A total of three interpolation passes at different ranges were carried out using distances derived from the omni-directional variogram results. All search ellipses adopted the dynamic search function of the Datamine software package in which the orientation of the search ellipse is varied so as to remain as parallel as possible to the local strikes and dips of the mineralization. A listing of the search strategies and estimation parameters used to estimate the metal grades for the calamine mineralization is presented in Table 11-24.

 

 

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Table 11-24:      Search Parameters and Estimation Strategies, Supergene Mineralization

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Item   Zinc     Lead     Silver  
Interpolation method     OK       OK       OK  
Search volume method     Ellipsoid       Ellipsoid       Ellipsoid  
Length of axis 1 (m)     30       30       30  
Length of axis 2 (m)     30       30       30  
Length of axis 3 (m)     30       30       30  
First rotation angle     40       40       40  
Second rotation angle     0       0       0  
Third rotation angle     20       20       20  
First rotation axis (1=X, 2=Y, 3=Z)     3       3       3  
Second rotation axis (1=X, 2=Y, 3=Z)     1       1       1  
Third rotation axis (1=X, 2=Y, 3=Z)     2       2       2  
Octant Definition Method     None       None       None  
Min. number of samples for first dynamic search volume     3       3       3  
Max. number of samples for first dynamic search volume     80       80       80  
Axis multiplying factor for second dynamic search volume     2       2       2  
Min. number of samples for second dynamic search volume     3       3       3  
Max. number of samples for second dynamic search volume     80       80       80  
Axis multiplying factor for third dynamic search volume     3       3       3  
Min. number of samples for third dynamic search volume     3       3       3  
Max. number of samples for third dynamic search volume     80       80       80  
Maximum multiplying factor     10       10       10  

 

 

 

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11.3.11 Block Model Validation

 

Block model validation exercises included several validation techniques that included examination of the global mean grades, preparation of swath plots, Q-Q plots, scatter plots, histogram comparison, and visual validation.

 

11.3.11.1 Global Estimate

 

Block model validation exercises consisted of visually comparing the volume of the coded blocks in the block model against the volume report of the respective wireframe models as a high level check that the block model has been correctly coded for each of the wireframes. No issues were noted.

 

A comparison of the average grades of the informing capped, declustered composite samples against the average estimated block grades was carried out (Table 11-25).

 

Table 11-25:      Comparison of Composite Sample Grades with Estimated Block Model Grades, Supergene Mineralization

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Item   Zinc
(% Zn)
    Lead
(% Pb)
    Silver
(g/t Ag)
 
Composite Mean     10.93       0.17       1.2  
Block Model Average     9.73       0.17       1.4  
Difference (Bm-Comp)     -1.20       0.00       +0.2  
% Difference (vs Comp)     -11 %     0 %     +18 %

 

Review of the results shows that the estimated zinc and lead grades are in reasonable agreement with the informing samples. While a high variance is observed for the silver grades, it is important to note that the variation is compared against a very low base and that the silver values do not provide a material contribution to the overall value.

 

11.3.11.2 Swath Plots

 

Nexa conducted an evaluation of the spatial accuracy of the estimated grades by constructing a series of swath plots that compared the average composite grades to the average estimated block model grades in plan, section, and longitudinal orientations. A sample swath plot for the zinc grades is presented in Figure 11-44. Review of the swath plot shows a reasonable agreement between the estimated grades and their respective informing composite samples.

 

 

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Source: Nexa

 

Figure 11-44:      Swath Plot for Zinc, Calamine

 

11.3.11.3 Quantile-Quantile Plots

 

The accuracy of the distribution of the zinc grades between the informing composite samples and the estimated block grades was examined by construction of Q-Q plots using the GSLIB software package (Figure 11-45). Very good agreement is observed in the distribution between the estimated zinc grades and the corresponding informing samples for the lower portion of the grade range up to approximately 26% Zn. A bias in favour of the estimated block grades (i.e. block grades are over-estimated) is observed above approximately 26% Zn. Review of the global mean values shows that this bias has not affected the overall average zinc grade.

 

 

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Source: Nexa

 

Figure 11-45:      Quantile-Quantile Plot of the Zinc Grades, Supergene

 

11.3.11.4 Scatter Plots

 

The accuracy of the distribution of the zinc grades between the informing composite samples and the estimated block grades was also examined by construction of a simple scatter plot using the GSLIB software package (Figure 11-46). The results show that a good agreement is generally present between the estimated zinc grades and their corresponding informing samples. A slight bias is observed however where the estimated block grades are higher than their informing composite samples for a small number of data points.

 

 

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Source: Nexa

 

Figure 11-46:      Scatter Plot of the Zinc Grades, Supergene

 

11.3.11.5 Histogram Comparison

 

The accuracy of the distribution of the zinc grades between the informing composite samples and the estimated block grades was also examined by construction of normal scores histograms and the results charted using MS Excel (Figure 11-47). Good agreement is observed in the grade distributions of the estimated zinc grades and their corresponding informing samples.

 

In SLR’s opinion, the validation performed by Nexa and SLR are typical industry standard validation techniques and in general, the results presented suggest that the block model has been completed to a high standard, in line with industry best practices.

 

 

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Source: Nexa

 

Figure 11-47:      Normal Scores Plot of the Zinc Grades, Supergene

 

11.3.12 Mineral Resource Classification

 

Definitions for Mineral Resource categories used in this Technical Report Summary are those defined by SEC in S-K 1300. Mineral Resources are classified into Measured, Indicated, and Inferred categories.

 

Mineralized material for each wireframe was initially classified into the Measured, Indicated, or Inferred Mineral Resource categories on the basis of the density of drill hole and chip sample information, and presence of underground access as follows:

 

Mineral Resource Category   Sample Spacing
Measured   10 m x 10 m
Indicated   20 m x 20 m
Inferred   >40 m x 40 m

 

Following the classification of the mineralized material into the initial Mineral Resource categories, clipping polygons were used in a final stage of the process to edit the initial classification assignments so as to ensure continuity and consistency of the final classified blocks in the model (Figure 11-48).

 

 

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Figure 11-48:       View of the Final Classified Mineral Resources, Supergene

 

 

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11.3.13 Net Smelter Return Cut-Off Value and Whittle Parameters

 

11.3.13.1 Net Smelter Return

 

An NSR cut-off value was determined using the Mineral Resource metal prices, metal recoveries, transport, treatment, and refining costs, as well as mine operating cost. Metal prices used for Mineral Resources are based on consensus, long term forecasts from banks, financial institutions, and other sources. All domestic costs were converted to an equivalent US dollar basis using an average long term exchange rate of R$4.84/US$.

 

The cut-off value used for the Mineral Resource estimate is based on an NSR value, in units of US$/t, which can be directly compared to operating unit costs. The NSR formula is:

 

 

Cut-off costs and NSR param

 

Cost information and NSR parameters used to code the block model are summarized in Table 11-26.

 

Table 11-26:      Block Model NSR Data- Calamine Mineralization

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Item   Units   Rock   Soil  
Metallurgical Recovery              
Zn   %   55.00   55.00  
Pb   %   46.38   46.38  
Ag   %   42.00   42.00  
Metal Payability              
Zn Concentrate Payable              
Zn   %   94.4   94.4  
Pb Concentrate Payable       95.0   95.0  
Pb   Min Payable/Deduction   95%/3% 95%/3%
Ag   Min Payable/Deduction   95%/50.0 g/t   95%/50.0 g/t  
Metal Prices              
Zn   US$/lb   1.30   1.30  
Pb   US$/lb   1.02   1.02  
Ag   US$/oz   19.38   19.38  
Transport Charges              
Zn Concentrate   US$/t conc.   16.60   16.60  
Pb Concentrate   US$/t conc.   278.72   278.72  
Treatment Charges              
Zn Concentrate   US$/t conc.   0   0  
Pb Concentrate   US$/t conc.   142.57   142.57  

 

 

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Item   Units   Rock     Soil  
Refining Charges                    
Ag in Pb Concentrate   US$/oz     1.00       1.00  
Integrated Zn (processed at Três Marias)                    
Premium   US$/t     286.31       286.31  
Conversion Cost   US$/t     473.95       473.95  
Operating Costs                    
Mining   US$/t proc.     4.62       3.23  
Processing   US$/t proc.     14.57       14.57  
G&A   US$/t proc.     5.45       5.45  
Total   US$/t proc.     24.64       23.39  

 

NSR calculations use a model head grade-recovery relationship for each metal, based on recent operating performance. The head grade and recovery curves are presented in Figure 11-49 and Figure 11-50. NSR factors are therefore variable by head grade, with average NSR factors summarized in Table 11-27. The average NSR factors are calculated using the LOM revenue contribution from each metal net of off-site costs and factors, divided by the reserve grade for that metal, and are indicative of the relative contribution of each metal unit to the economics of the mine. For most metals, a variable recovery (as a function of head grade) was used, and therefore the average NSR factors should not be applied to head grades without considering the head grade versus recovery relationship.

 

 

Source: Nexa

 

Figure 11-49:      Zinc Grade-Recovery Curve for the Supergene Mineralization

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Source: Nexa

 

Figure 11-50:      Lead Grade-Recovery Curve for the Supergene Mineralization

 

Table 11-27:      Average NSR Factors for the Supergene Mineralization

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Item     Units   Value  
  Zn     US$/% Zn     13.55  
  Pb     US$/% Pb     1.39  
  Ag     US$/oz Ag     6.88  

 

Metal prices are based on Nexa’s projections. Nexa’s long term price model uses multiple variables including supply (mine and refined), demand, cost drivers, capital cost, and other key elements. The long term prices derived are in line with the consensus forecasts from banks and independent institutions.

 

11.3.13.2 Whittle Pit Shell Parameters

 

The conceptual operational scenario that is envisioned in relation to the Mineral Resource estimates of the supergene mineralization is to continue excavation of the mineralized material by means of open pit mining methods, with the mineralized material being processed using the existing plant facilities. As an aid in preparation of the Mineral Resource statement, an open pit shell was created by Nexa using the GEOVIA Whittle software package and the parameters presented in Table 11-28. The open pit shell was created using the updated, re-blocked model of the calamine mineralization. This block model was modified to assign a destination code for the material types as being sent either to the plant or to the waste rock storage area. The NSR cut-off values used to determine the material destination were $20.16/t processed for soil and $20.02/t processed for fresh rock and transition zone material. The resulting pit surface is presented in Figure 11-51.

 

 

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Table 11-28:      Summary of the Whittle Input Parameters

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Item   Description   Units   Value  
Geotechnical Info
Overall Angle   Soil   °     39.00  
    Rock and Transition   °     46.00  
Costs
Mining   Soil   US$/t total material     3.23  
    Rock and Transition   US$/t total material     4.62  
Process   Soil   US$/t ore     14.71  
    Rock and Transition   US$/t ore     14.57  
G&A   Soil   US$/t ore     5.45  
    Rock and Transition   US$/t ore     5.45  
Conversion Cost   All   US$/t Zn     473.95  
Macro Economics
Exchange Rate   BRL/USD     4.84  
    Zinc   US$/t     2,869.14  
Price   Lead   US$/t     2,249.40  
    Silver   US$/oz     19.38  
Premium   Zinc   US$/t     286.31  
Logistics   Zinc (to TM)   US$/t conc.     16.60  
    Lead (Export)   US$/t conc.     278.72  
Metallurgical Recovery
    Zinc   %     55.00  
Vazante   Lead   %     46.38  
    Silver @ Pb Conc.   %     42.00  
Três Marias   Zinc   %     94.40  
Cut-off Value
Cut off Value   Soil   US$/t ore     20.16  
    Rock and Transition   US$/t ore     20.02  

 

 

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Figure 11-51:      Plan View of the Open Pit Surface, Supergene Mineral Resources

 

 

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11.3.14 Mineral Resource Reporting

 

Mineral Resources are prepared in accordance with the definitions for Mineral Resources in S-K 1300, which are consistent with CIM (2014) definitions.

 

The Mineral Resources are exclusive of Mineral Reserves. The Mineral Resources are located within an open pit shell that was created in consideration of appropriate metal prices, mining costs, metallurgical recoveries, and geotechnical considerations. The open pit shell was used to aid in the reporting of the Mineral Resources to ensure that the “Reasonable Prospects” requirement of S-K 1300 is met. The Mineral Resources for the supergene calamine mineralization are presented in Table 11-29. No previous Mineral Resources have been disclosed by Nexa in respect of the supergene mineralization.

 

In SLR’s opinion, the assumptions, parameters, and methodology used for the Vazante supergene Mineral Resource estimates are appropriate for the style of mineralization and anticipated mining methods.

 

The SLR QP is of the opinion that, with consideration of the recommendations summarized in Section 1 and Section 23, any issues relating to all relevant technical and economic factors likely to influence the prospect of economic extraction can be resolved with further work

 

Table 11-29:     Mineral Resources For the Calamine Mineralization as of December 31, 2020

Nexa Resources S.A. – Vazante Polymetallic Operations

 

    Tonnes     Grade     Contained Metal  
Category   (000 t)     (% Zn)     (% Pb)     (g/t Ag)     (000 t Zn)     (000 t Pb)     (000 oz Ag)  
Measured     0       0       0       0       0       0       0  
Indicated     880       9.13       0.16       1.2       80.34       1.40       34.0  
Subtotal, M&I     880       9.13       0.16       1.2       80.34       1.41       34.0  
Inferred     870       9.92       0.09       1.1       86.30       0.78       30.8  

 

Notes:

 

1. The definitions for Mineral Resources in S-K 1300 were followed for Mineral Resources which are consistent with CIM (2014) definitions.

 

2. Mineral Resources are reported on a 100% ownership basis.

 

3. Mineral Resources are estimated at a NSR cut-off value of US$20.16/t for soil and US$20.02/t for fresh rock and transition material.

 

4. Mineral Resources are estimated using average long term metal prices of Zn: US$2,869.14/t (US$1.30/lb), Pb: US$2,249.40/t (US$1.02/lb), and Ag: US$19.38/oz, and metallurgical recoveries are based on recovery curves derived from historical processing data. An average long term R$/US$ exchange rate of 4.84 was used.

 

5. Bulk density varies depending on the degree of weathering.

 

6. Mineral Resources are exclusive of Mineral Reserves.

 

7. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability.

 

8. Mineral Resources are reported for all material contained an open pit shell with grades above the nominated NSR cut-off values.

 

9. Numbers may not add due to rounding.

 

11.3.15 Risks and Uncertainties to Mineral Resources

 

Based on SLR’s review of the supergene (calamine) Mineral Resource estimate, the following key risks have been identified:

 

 

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· Due to the natural variability inherent to the calamine mineralization, the presence, location, size, shape, and grade of the actual mineralization between the existing sample points may differ from the current interpretation. The level of uncertainty in these items is lowest for the Indicated Mineral Resource category and is highest for the Inferred Mineral Resource category. This risk item can be improved with increased density of drill hole and channel sample data.

 

· Due to the natural variability in the porosity of the host rocks, the local density for any portion of the Mineral Resources may vary from the estimated value, resulting in either an increase or decrease in the tonnage estimate at the local scale. The density estimates can be improved with increased density of drill hole and channel sample data.

 

· Due to the current level of drill hole information, the detailed distribution of the weathered and un-weathered materials may differ from the current interpretations, potentially resulting in changes to the reporting surface used to prepare the Mineral Resource statement. This risk item can be improved with increased density of drill hole and channel sample data.

 

· Changes in the metallurgical recoveries from the estimated values used in preparation of the Mineral Resource statement can impact on the amount of metal recovered at time of production. This risk item can be improved by completion of additional metallurgical test work.

 

· Due to variations in the global supply chain, the actual metal prices realized at the time of production may differ from the long term metal prices that were used in the preparation of the Mineral Resource statements. Lower zinc metal prices realized at the time of production may result in a decrease in Mineral Resources. In SLR’s opinion the Mineral Resources are not sensitive to variations in the prices of silver or lead from those used in the current Mineral Resource statement.

 

· The cut-off grade (or value) used in preparation of the current Mineral Resource statement can be affected by variations in the Brazilian Real and United States dollar exchange rate. A strengthening of the Brazilian Real versus the United States dollar may result in an increase in the cut-off grade (or value), with a corresponding decrease in the Mineral Resources.

 

11.4 Aroeira Tailings

 

11.4.1 Resource Database

 

Drill hole information for the Aroeira tailings mineralization was extracted from the Fusion™ database into separate files for use in preparation of the Mineral Resource estimates. This drill hole information was modified slightly so as to be compatible with the format requirements of the Datamine and Leapfrog modelling packages and were imported into those software package by Nexa. A number of new tables and variables were created during the estimation process to capture such information as the interpreted mineralized intersection length along the drill holes, density readings, capped assay values, and composite values.

 

The cut-off date for the assays in the drill hole database is December 31, 2019. Drilling and sampling were carried out using the UTM Datum Cόrrego Alegre, Zone 23S grid coordinate system. The northing and easting collar coordinates of the drill holes and channel samples used to prepare the Mineral Resource estimate for the Aroeira tailings mineralization remained in the UTM coordinate system. This is in contrast to the drill hole and channel sample information used to estimate the hypogene mineralization that has been converted to the mine grid coordinate system.

 

 

 

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SLR recommends that the drill hole data relating to the tailings mineralization be converted into the mine grid coordinate system to more easily integrate the information for the underground mine.

 

A summary of the drilling information for the Aroeira and Antiga tailings areas is provided in Table 11-30. The location of the drill holes is shown in Figure 11-52.

 

Table 11-30:     Summary of Drill Hole Database, Tailings Mineralization

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Data Type   Number of Records  
Collar     113  
Down hole survey     95  
Assays     1,345  
Composites (within mineralized
wireframe boundaries)
    490  

 

 

 

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Figure 11-52:        Drill Hole Location Map, Tailings Sampling Programs

 

 

 

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11.4.2 Mineralized Wireframe Interpretation

 

A mineralized wireframe of the Aroeira tailings was prepared for the material encountered in the drill holes completed as part of the tailings sampling program using the Leapfrog software package. It is important to note that the portion of the Aroeira tailings that was sampled by the drilling program comprises only a portion of the total volume of tailings that are currently stored in the Aroeira TSF (Figure 11-53). The mineralized wireframe was drawn to represent the volume of tailings that were encountered by the drilling program and excluded material which formed part of the original pre-deposition surface.

 

The resulting mineralization wireframe included 34 completed drill holes covering an area of the tailings measuring approximately 500 m in an east-west direction and approximately 550 m in a north-south direction. The drill holes were completed on a nominal spacing of 50 m x 50 m (Figure 11-54). A sample cross section is provided in Section 7.2 of this Technical Report Summary.

 

 

 

Source: Nexa

 

Figure 11-53:     Inclined View of the Planned vs Completed Drill Holes, Aroeira Tailings

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Figure 11-54:    Plan View of the Drill Hole Locations and Mineralized Wireframe, Aroeira Tailings

 

 

 

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11.4.3 Topography Surfaces

 

The original, pre-deposition topographic surface used to prepare the digital interpretation of the tailings volume perimeter was derived from an available topographic map that was prepared by the Brazilian government. The original topographic surface was presented in the form of contour lines that had limited precision and accuracy.

 

Nexa carried out an updated topographic survey of the Aroeira TSF area on December 8, 2020 using a Phantom 4 Pro drone that was equipped with a Leica GS18 RTK GPS unit (Figure 11-55). The average survey accuracy of this equipment is stated as 0.03 m.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Figure 11-55:       View of the Aroeira Tailings Storage Area as of December 8, 2020

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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11.4.4 Resource Assays

 

The mineralization wireframe model was used to code the drill hole database and identify the raw assay samples, or resource assays, that are contained within the mineralized wireframe. These samples were extracted from the database and then subjected to statistical analyses by means of histograms and probability plots. A total of 464 zinc samples were contained within the Aroeira tailings mineralized wireframe model. The resource assay sample statistics and selected capping values for the uncapped assay values are summarized in Table 11-31. Histogram charts of the zinc, lead, and silver grades are provided in Figure 11-56, Figure 11-57, and Figure 11-58

 

Table 11-31:     Summary of Uncapped, Clustered Raw Sample Statistics, Aroeira Tailings

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Item   Zinc
(% Zn)
    Lead
(% Pb)
    Silver
(g/t Ag)
 
Mean     4.26       0.26       8.2  
Median     3.96       0.26       6.5  
Standard Deviation     1.53       0.07       5.6  
Coefficient of Variation     0.36       0.27       0.7  
Minimum     0.05       0.00       0.3  
Maximum     9.6       0.78       49.8  
Number of Samples     464       464       464  
Capping Value     8.0       No capping applied       No capping applied  

 

 

 

Figure 11-56:     Frequency Histogram of the Zinc Uncapped Raw Sample Statistics, Aroeira Tailings

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000 

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Figure 11-57:     Frequency Histogram of the Lead Uncapped Raw Sample Statistics, Aroeira Tailings

 

 

 

Figure 11-58:     Frequency Histogram of the Silver Uncapped Raw Sample Statistics, Aroeira Tailings

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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11.4.5 Treatment of High Grade Assays

 

In order to reduce the influence of high grade sample values, a simple capping approach was applied. In this method, the grades of the resource assays contained within the respective mineralized wireframes that are deemed to represent anomalously high grades are reduced to a maximum value – the capping grade. A capping value of 8% Zn was applied to the zinc raw assays. No capping values were applied to the lead or silver assays.

 

11.4.6 Compositing

 

All samples contained within the Aroeira tailings mineralized wireframe had 1.2 m sample lengths, consequently compositing of samples into equal lengths was not required (Figure 11-59). A summary of the capped assays is presented in Table 11-32.

 

 

 

Source: Nexa

 

Figure 11-59:     Histogram of Sample Lengths, Aroeira Tailings Samples

 

Table 11-32:     Summary of Capped, Composite Statistics, Aroeira Tailings

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Item   Zinc
(% Zn)
    Lead
(% Pb)
    Silver
(g/t Ag)
 
Mean     4.24       0.26       8.2  
Median     3.96       0.25       6.5  
Standard Deviation     1.50       0.07       5.6  
Coefficient of Variation     0.35       0.27       0.7  
Minimum     0.05       0.00       0.3  
Maximum     8.00       0.78       49.8  
Number of Samples     464       464       464  

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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11.4.7 Bulk Density

 

A total of 452 dry bulk density measurements were collected from drill hole samples of the Aroeira tailings, of which 431 were contained within the mineralized wireframe. These samples have bulk densities ranging from 1.01 t/m3 to 2.56 t/m3, with a mean bulk density of 1.71 t/m3 (Figure 11-60).

 

The bulk densities of each of these samples were used to estimate the block model density using the Inverse Distance, Power 2 interpolation algorithm. A minimum of five and a maximum of 30 samples were used to estimate the bulk densities to the block model.

 

 

 

Source: Nexa

 

Figure 11-60:     Distribution of Dry Bulk Density Measurements, Aroeira Tailings

 

 

 

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11.4.8 Trend Analysis

 

11.4.8.1 Variography

 

Nexa began its analysis of the spatial continuity by constructing separate downhole and omni-directional variograms using the composite data for the zinc, lead, and silver grades for the Aroeira tailings mineralized wireframe, with the objective of determining an appropriate value for the global nugget (C0). The analysis then proceeded with the preparation of directional variograms to search for any anisotropies that may be present in the data, which resulted in variograms with reasonable model fits (Figure 11-61).

 

The GSLIB software package was used to calculate the variograms and charts of the results were prepared using Nexa’s in-house software. The left hand rule was used as the rotation convention wherein the Y axis is the direction of maximum continuity (major axis), the X axis is the direction of the semi-major axis and the Z axis is the direction of the minor axis. A summary of the variogram parameters is presented in Table 11-33.

 

 

 

Source: Nexa

 

Figure 11-61:     Example Variograms for Zinc Grades Contained Within the Aroeira Tailings Mineralized Wireframe Domain

 

Table 11-33:     Summary of Variogram Parameters, Aroeira Tailings

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Item   Zinc     Lead     Silver  
C0 Nugget     0.35       0.35       0.35  
C1 1st structure     0.25       0.25       0.25  
C2 2nd structure     0.25       0.25       0.25  
C3 3rd structure     0.15       0.15       0.15  
A1 1st Range Z     3       3       3  
A2 2nd Range Z     8       8       8  
A3 3rd Range Z     10       10       10  
A1 1st Range X     20       20       20  
A2 2nd Range X     50       50       50  
A3 3rd Range X     160       160       160  
A1 1st Range Y     20       20       20  
A2 2nd Range Y     80       80       80  
A3 3rd Range Y     200       200       200  

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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11.4.9 Block Model Construction

 

An initial block model was constructed by Nexa using the Datamine software package and the UTM coordinate system. The block model used a parent block size of 25 m (X) x 25 (Y) m x 2 m (Z) sized blocks and using sub-blocking with a minimum block size of 1 m (X) x 1 m (Y) x 1 m (Z). The block models are oriented parallel to the UTM grid coordinate grid system (i.e., no rotation or tilt). The block model origin and dimensions are provided in Table 11-34. A number of attributes were created to store such information as rock code, material densities, estimated metal grades, and the like (Table 11-35).

 

Table 11-34:     Initial Block Model Definition, Aroeira Tailings

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Type   Units   Y
(Northing)
    X
(Easting)
    Z
(Elevation)
 
Minimum Coordinates   m     8,012,556       306,704       595  
Maximum Coordinates   m     8,013,181       307,229       629  
Parent Block Size   m     25       25       2  
Sub-block Size   m     1       1       1  
Rotation   °     0.000       0.000       0.000  

 

Table 11-35:     List of Initial Block Model Attributes, Aroeira Tailings

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Attribute Name   Type     Decimals     Background     Description
ag     Real       0       0     Silver in oz/t
corpo     Character       -              
density     Real       0       0      
fe     Real       0       0      
kvar     Real       0       -1e+30      
nsam     Real       0       -1e+30      
ore     Real       0       -1e+30      
oxide     Real       0       -1e+30      
pb     Real       0       0     Lead in percent
resource     Real       0       -1e+30      
svol     Real       0       -1e+30      
tonnes     Real       0       -1e+30      
zn     Real       0       0     Zinc in percent
zone     Real       0       0      

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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The initial block model was subsequently re-blocked to blocks of equal size that measured 5 m x 5 m x 2 m in size. A number of blocks were created as part of the re-blocking effort which extended beyond the limits of the mineralization boundary. These blocks were removed from the final re-blocked model so as to reflect the tonnage and grades of the source block model more accurately. A number of attributes were also added to permit the calculation of a NSR value and preparation of the Mineral Resource statement. The revised attribute list is shown in Table 11-36.

 

Table 11-36:     List of Re-Blocked Block Model Attributes, Aroeira Tailings

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Attribute Name   Type   Decimals     Background     Description
ag   Real     0       0     Silver in oz/t
agppm   Real     0       0     Silver in g/t
cog   Character     -              
density   Real     0       0      
fe   Real     0       0      
fillvol   Real     0       -1e+30      
kvar   Real     0       -1e+30      
nsam   Real     0       -1e+30      
nsr20res   Real     0       0      
ore   Real     0       -1e+30      
oxide   Real     0       -1e+30      
pb   Real     0       0      
rec_agpb   Real     0       0      
rec_agzn   Real     0       0      
rec_pb   Real     0       0      

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Attribute Name       Type       Decimals       Background   Description  
rec_zn       Real       0       0      
resource       Real       0       -1e+30      
svol       Real       0       -1e+30      
tonnes       Real       0       -1e+30      
voidvol       Real       0       -1e+30      
zn       Real       0       0      
zone       Real        0       0      

 

11.4.10 Search Strategy and Grade Interpolation Parameters

 

Metal grades were estimated into the blocks by means of the OK interpolation algorithm. A single interpolation pass was carried out using distances derived from the directional variogram results. A listing of the search strategies and estimation parameters used to estimate the metal grades for the Aroeira tailings mineralization is presented in Table 11-37.

 

Table 11-37:      Search Parameters and Estimation Strategies, Aroeira Tailings

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Item   Zinc     Lead     Silver  
Interpolation method   OK     OK     OK  
Search volume method   Ellipsoid     Ellipsoid     Ellipsoid  
Length of axis 1 (m)     160       160       160  
Length of axis 2 (m)     200       200       200  
Length of axis 3 (m)     10       10       10  
First rotation angle     0       0       0  
Second rotation angle     0       0       0  
Third rotation angle     0       0       0  
First rotation axis (1=X, 2=Y, 3=Z)     3       3       3  
Second rotation axis (1=X, 2=Y, 3=Z)     1       1       1  
Third rotation axis (1=X, 2=Y, 3=Z)     2       2       2  
Octant Definition Method     None       None       None  
Min. number of samples     1       1       1  
Max. number of samples     40       40       40  
Maximum multiplying factor     3       3       3  

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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11.4.11 Block Model Validation

 

Block model validation exercises included several validation techniques that included examination of the global mean grades, preparation of swath plots, Q-Q plots, scatter plots, histogram comparison, and visual validation.

 

11.4.11.1 Global Estimate

 

Block model validation exercises consisted of visually comparing the volume of the coded blocks in the block model against the volume report of the respective wireframe models as a high level check that the block model has been correctly coded for each of the wireframes. No issues were noted.

 

A comparison of the average grades of the informing capped, declustered composite samples against the average estimated block grades was carried out (Table 11-38).

 

Table 11-38:      Comparison of Composite Sample Grades with Estimated Re-Blocked Model Grades, Aroeira Tailings

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Item   Zinc
(% Zn)
    Lead
(% Pb)
    Silver
(g/t Ag)
 
Composite Mean     4.24       0.26       8.2  
Block Model Average     3.81       0.24       7.4  
Difference (Bm-Comp)     -0.43       -0.02       -0.8  
% Difference (vs Comp)     -10 %     -8 %     -10 %

 

Review of the results shows that the estimated zinc, lead, and silver grades are in reasonable agreement with the informing samples.

 

11.4.11.2 Swath Plots

 

Nexa conducted an evaluation of the spatial accuracy of the estimated grades by constructing a series of swath plots that compared the average composite grades to the average estimated block model grades in plan, section, and longitudinal orientations. A sample swath plot for the zinc grades is presented in Figure 11-62. Review of the swath plot shows a reasonable agreement between the estimated grades and their respective informing composite samples.

 

11.4.11.3 Quantile-Quantile Plots

 

The accuracy of the distribution of the zinc grades between the informing composite samples and the estimated block grades was examined by construction of Q-Q plots using the GSLIB software package (Figure 11-63). Very good agreement is observed in the distribution between the estimated zinc grades and the corresponding informing samples for the lower portion of the grade range up to approximately 5.5% Zn. A bias in favour of the estimated block grades (i.e. block grades are over-estimated) is observed above approximately 5.5% Zn. Review of the global mean values shows that this bias has not affected the overall average zinc grade.

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Figure 11-62:   Swath Plot for Zinc, Aroeira Tailings

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Source: Nexa

 

Figure 11-63:      Quantile-Quantile Plot of the Zinc Grades, Aroeira Tailings

 

11.4.11.4 Scatter Plots

 

The accuracy of the distribution of the zinc grades between the informing composite samples and the estimated block grades was also examined by construction of a simple scatter plot using the GSLIB software package (Figure 11-64). The results show that a good agreement is generally present between the estimated zinc grades and their corresponding informing samples.

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Source: Nexa

 

Figure 11-64:      Scatter Plot of the Zinc Grades, Aroeira Tailings

 

11.4.11.5 Histogram Comparison

 

The accuracy of the distribution of the zinc grades between the informing composite samples and the estimated block grades was also examined by construction of normal scores histograms and the results charted using MS Excel (Figure 11-65). Good agreement is observed in the grade distributions of the estimated zinc grades and their corresponding informing samples.

 

In SLR’s opinion, the validation performed by Nexa and SLR are typical industry standard validation techniques and in general, the results presented suggest that the block model has been completed to a high standard, in line with industry best practices.

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Source: Nexa

 

Figure 11-65:      Normal Scores Plot of the Zinc Grades, Aroeira Tailings

 

11.4.12 Mineral Resource Classification

 

Definitions for Mineral Resource categories used in this Technical Report Summary are those defined by SEC in S-K 1300. Mineral Resources are classified into Measured, Indicated, and Inferred categories.

 

All mineralized material within the mineralized wireframe was classified into the Inferred Mineral Resource category.

 

11.4.13 Net Smelter Return Cut-Off Value Parameters

 

Nexa has been re-processing tailings from the Aroeira tailings storage area on an intermittent basis since 2018. This has been achieved by excavation of the tailings in one metre lifts using conventional hydraulic excavators which load the tailings into 15 t haulage trucks (Figure 11-66). The programs have been carried out during the dry season when the tailings are able to support the weight of the equipment. The tailings have been transported to the processing plant where they are added to the plant feed at the blending pads.

 

The conceptual operational scenario that is envisioned in relation to the Mineral Resource estimates of the Aroeira tailings mineralization is to continue excavation of the mineralized material by means of open cut mining methods, with the mineralized material being processed using the existing plant facilities. The excavation activities could continue until the original topographic surface is encountered.

 

An NSR cut-off value was determined using the Mineral Resource metal prices, metal recoveries, transport, treatment, and refining costs, as well as mine operating cost. Metal prices used for Mineral Resources are based on consensus, long term forecasts from banks, financial institutions, and other sources. All domestic costs were converted to an equivalent US dollar basis using an average long term exchange rate of R$4.84/US$.

 

 

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The cut-off value used for the Resource estimate is based on an NSR value, in units of US$/t, which can be directly compared to operating unit costs. The NSR formula is:

 

 

 

Source: Nexa

 

Figure 11-66:      Excavation of the Aroeira Tailings

 

Cost information and NSR parameters used to code the block model are summarized in Table 11-39.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Table 11-39:      Block Model NSR Data- Aroeira Tailings

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Item   Units   Value  
Metallurgical Recovery            
Zn   %     76.25  
Pb   %     23.35  
Ag   %     0.00  
Metal Payability            
Zn Concentrate Payable            
Zn   %     94.4  
Pb Concentrate Payable         95.0  
Pb   Min Payable/Deduction     95%/3%
Ag   Min Payable/Deduction     95%/50.0 g/t  
Metal Prices            
Zn   US$/lb     1.30  
Pb   US$/lb     1.02  
Ag   US$/oz     19.38  
Transport Charges            
Zn Concentrate   US$/t conc.     16.60  
Pb Concentrate   US$/t conc.     278.72  
Treatment Charges            
Zn Concentrate   US$/t conc.     0  
Pb Concentrate   US$/t conc.     142.57  
Refining Charges            
Ag in Pb Concentrate   US$/oz     1.00  
Integrated Zn (processed at Três Marias)            
Premium   US$/t     286.31  
Conversion Cost   US$/t     473.95  
Operating Costs            
Mining   US$/t proc.     0.60  
Processing   US$/t proc.     14.57  
G&A   US$/t proc.     5.45  
Total   US$/t proc.     20.62  

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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NSR calculations use a model head grade-recovery relationship for each metal, based on recent operating performance. The head grade and recovery curves are presented in Figure 11-67 and Figure 11-68. NSR factors are therefore variable by head grade, with average NSR factors summarized in Table 11-40. The average NSR factors are calculated using the LOM revenue contribution from each metal net of off-site costs and factors, divided by the reserve grade for that metal, and are indicative of the relative contribution of each metal unit to the economics of the mine. For most metals, a variable recovery (as a function of head grade) was used, and therefore the average NSR factors should not be applied to head grades without considering the head grade versus recovery relationship.

 

 

Source: Nexa

 

Figure 11-67:      Zinc Grade-Recovery Curve for the Aroeira Tailings

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Source: Nexa

 

Figure 11-68:      Lead Grade-Recovery Curve for the Aroeira Tailings

 

Table 11-40:      Average NSR Factors for the Aroeira Tailings

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Item     Units     Value  
Zn       US$/%       18.75  
Pb       US$/%       1.39  
Ag       US$/oz       6.88  

 

Metal prices are based on Nexa’s projections. Nexa’s long term price model uses multiple variables including supply (mine and refined), demand, cost drivers, capital cost, and other key elements. The long term prices derived are in line with the consensus forecasts from banks and independent institutions.

 

11.4.14 Mineral Resource Reporting

 

Mineral Resources are prepared in accordance with the definitions for Mineral Resources in S-K 1300, which are consistent with CIM (2014) definitions.

 

The Mineral Resources are exclusive of Mineral Reserves. The Mineral Resources comprise material with an NSR value of greater than US$20.62/t which lies above the original topographic surface. As the original topographic surface represents a stable slope, SLR is of the opinion that this is sufficient to satisfy the “Reasonable Prospects” requirement of S-K 1300. The Mineral Resources for the Aroeira tailings mineralization are presented in Table 11-41. No previous Mineral Resources have been disclosed by Nexa in respect to the Aroeira tailings mineralization.

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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.

 

 

In SLR’s opinion, the assumptions, parameters, and methodology used for the Aroeira tailings Mineral Resource estimates are appropriate for the style of mineralization and anticipated mining methods.

 

The SLR QP is of the opinion that, with consideration of the recommendations summarized in Section 1 and Section 23, any issues relating to all relevant technical and economic factors likely to influence the prospect of economic extraction can be resolved with further work.

 

Table 11-41:          Mineral Resources for the Aroeira Tailings as of December 31, 2020

Nexa Resources S.A. – Vazante Polymetallic Operations

 

  Tonnes     Grade     Contained Metal  
Category   (000 t)     (% Zn)     (% Pb)     (g/t Ag)     (000 t Zn)     (000 t Pb)     (000 oz Ag)  
Measured   0     0     0     0     0     0     0  
Indicated   0     0     0     0     0     0     0  
Subtotal, M&I   0     0     0     0     0     0     0  
                                           
Inferred   3,939     4.06     0.25     7.8     160     9.9     995  

 

Notes:

 

1. The definitions for Mineral Resources in S-K 1300 were followed for Mineral Resources which are consistent with CIM (2014) definitions.
2. Mineral Resources are reported on a 100% ownership basis.
3. Mineral Resources are estimated at a NSR cut-off value of US$20.62/t.
4. Mineral Resources are estimated using average long term metal prices of Zn: US$2,869.14/t (US$1.30/lb), Pb: US$2,249.40/t (US$1.02/lb), and Ag: US$19.38/oz, and metallurgical recoveries are based on recovery curves derived from historical processing data and test work. An average long term R$/US$ exchange rate of 4.84 was used.
5. The average bulk density is 1.71 t/m3.
6. Mineral Resources are exclusive of Mineral Reserves.
7. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability.
8. Mineral Resources are reported for all material with grades above the nominated NSR cut-off values and above the original topographic surface.
9. Numbers may not add due to rounding.

 

11.4.15 Risks and Uncertainties to Mineral Resources

 

Based on SLR’s review of the tailings Mineral Resource estimate, the following key risks have been identified:

 

· Due to the variability inherent to the tailings mineralization, the presence, location, size, shape, and grade of the actual mineralization between the existing sample points may differ from the current interpretation. This risk item can be addressed by completion of additional drilling and sampling programs.

 

· Due to the natural variability in the dry bulk density of the mineralized material, the local density for any portion of the Mineral Resources may vary from the estimated value, resulting in either an increase or decrease in the tonnage estimate at the local scale. This risk item can be improved with increased density of drill hole data.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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· Changes in the metallurgical recoveries from the estimated values used in preparation of the Mineral Resource statement can impact on the amount of metal recovered at time of production. This risk item can be improved by completion of additional metallurgical test work.

 

· Due to variations in the global supply chain, the actual metal prices realized at the time of production may differ from the long term metal prices that were used in the preparation of the Mineral Resource statements. Lower zinc metal prices realized at the time of production may result in a decrease in Mineral Resources. In SLR’s opinion the Mineral Resources are not sensitive to variations in the prices of silver or lead from those used in the current Mineral Resource statement.

 

· The cut-off grade (or value) used in preparation of the current Mineral Resource statement can be affected by variations in the Brazilian Real and United States dollar exchange rate. A strengthening of the Brazilian Real versus the United States dollar may result in an increase in the cut-off grade (or value), with a corresponding decrease in the Mineral Resources.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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12.0 Mineral Reserve Estimates

 

12.1 Summary

 

The Mineral Reserves estimate for the Vazante Operation as at December 31, 2020 is presented in Table 12-1.

 

SLR is of the opinion that the Mineral Reserves have been prepared in an appropriate manner consistent with good engineering practices and completed by competent professional personnel.

 

Table 12-1:       Summary of Mineral Reserves as of December 31, 2020

Nexa Resources S.A. – Vazante Polymetallic Operations

 

  Tonnes     Grade     Contained Metal  
Deposit/Category   (000 t)     (% Zn)     (% Pb)     (g/t Ag)     (000 t Zn)     (000 t Pb)     (000 oz Ag)  
Lumiadeira                                          
Proven     3,410       8.93       0.22       20.78       304.5       7.6       2,278  
Probable     3,260       8.86       0.22       18.44       289.0       7.2       1,933  
Proven & Probable     6,670       8.90       0.22       19.64       593.5       14.8       4,211  
                                                         
Sucuri                                                        
Proven     3,408       8.41       0.26       13.74       286.8       9.0       1,505  
Probable     1,225       7.17       0.26       11.40       87.9       3.2       449  
Proven & Probable     4,633       8.09       0.26       13.12       374.7       12.3       1,954  
                                                         
Extremo Norte                                                        
Proven     1,621       7.25       0.24       6.57       117.5       4.0       342  
Probable     3,760       9.34       0.18       7.11       351.0       6.9       860  
Proven & Probable     5,381       8.71       0.20       6.95       468.6       10.9       1,202  
                                                         
Total                                                        
Proven     8,439       8.40       0.24       15.20       708.8       20.6       4,125  
Probable     8,245       8.83       0.21       12.23       727.9       17.4       3,241  
Proven & Probable     16,684       8.61       0.23       13.73       1,436.7       38.0       7,367  

 

Notes:

 

1. The definitions for Mineral Reserves in S-K 1300 were followed for Mineral Reserves which are consistent with CIM (2014) definitions.
2. Mineral Reserves are estimated at a cut-off NSR value of US$47.49/t processed.
3. Mineral Reserves are estimated using an average long term metal prices of US$2,494.90/t Zn, US$1,956.00/t Pb and US$16.85/oz Ag and a R$/US$ exchange rate of 4.84.
4. A minimum mining width of 4.0 m was used.
5. Bulk density is 3.1 t/m3.
6. Numbers may not add due to rounding.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Nexa reviewed supply and demand projections for zinc, lead, and silver, as well as consensus long term (10 year) metal price forecasts. SLR verified that Nexa’s selected metal prices for estimating Mineral Reserves are in line with independent forecasts from banks and other lenders.

 

The SLR QP is not aware of any risk factors associated with or changes to any aspect of the modifying factors such as mining, metallurgical, infrastructure, permitting, or other relevant factors that could materially affect the Mineral Reserve estimate.

 

12.1.1 Mineral Reserve Process

 

Mineral Reserves were estimated by flagging mined-out stope surveys through September 2020 and planned mining to December 31, 2020, as zero-values in the block model.  After year end, SLR verified the estimate by reviewing actual mining results for the short period of projected mining.  Deviations from plan, amounting to approximately 1% of total Mineral Reserves tonnage, were caused by 2020 infill drilling and mining of some areas classified as Inferred at the time of the estimate.  SLR considers these deviations to be typical of ongoing mining operations, and not significant or material to the Mineral Reserves estimate.

 

The Mineral Reserve estimation process commences with the generation of cross sections through the deposit. Sections are generally spaced at 70 m along strike which is consistent with the planned stope dimensions.

 

The NSR calculation is prepared in a MS Excel spreadsheet to calculate the NSR for a given set of metal grades. The NSR calculation is applied to the resource block model, with stopes then evaluated to determine if the stope value exceeds the cut-off grade. This is followed by the completion of stope and development design. Mineral Reserves are depleted to the start date and the production schedule is then completed using the Deswik scheduling software. Dilution and extraction values are applied in the scheduling software.

 

12.2 Dilution

 

Dilution at the Vazante Operation is challenging to estimate and accurately predict due to the varying mineralization geometry. The current dilution factors used are shown in Table 12-2.

 

Table 12-2:         Mine Dilution

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Type   Method   Long Term   Source  
Operational Dilution   SLS (m) Dip<60 deg   0.25m (FW) / 0.75m (HW)   Historical  
    SLS (m) 60<Dip<80 deg   0.5m(HW)   Historical  
    SLS (m) Dip>80 deg   0 m   Historical  
    CAF (%)   12 %   Historical  
Planned Dilution   CAF (%)   Variable   Design  
    SLS (%)   Variable   Design  

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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SLR notes that the planned dilution for SLS uses a new methodology which assumes an estimate of the equivalent length of slough (ELOS, m) depending on the dip of the stope, ranging from zero metres to 0.75 m in the hanging wall and zero metres to 0.25 m in the footwall. SLR is of the opinion that the dilution factors indicated in Table 12-2 appear to be on the low side, as the reported planned dilution for 2020 YE was 26.1% and the operational dilution was 19.4%, with the total dilution for 2020 totalling approximately 45.5%. For comparison, Table 12-3 below shows the 2020 Mining Quality Control program outlining dilution and recovery results for the year.

 

Table 12-3:       Mining Quality Control 2020

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Month   Planned Dilution
(%)
  Operational Dilution
(%)
  Mining Recovery
(%)
January   35.5   15.5   78.8
February   21.3   23.7   96.9
March   15.6   20.6   97.9
April   17.3   21.2   94
May   21.1   21.8   88.6
June   24.7   22.5   81.8
July   27.1   20.3   85.5
August   28   12.8   76.9
September   30.9   20   86.5
October   28.8   20.8   94.2
November   36.7   15.4   84
December   26.7   17.7   86.1
Total   26.1   19.4   87.6

 

SLR has reviewed the impacts of changes to the dilution estimate. While increasing dilution could render some Mineral Reserves below cut-off grade the proportion is relatively low and overall, the Mineral Reserves are relatively insensitive to dilution fluctuations.

 

In SLR’s opinion the high dilution is caused in part by the current cable bolting procedure, whereby bolts are installed from the undercut level and fanned into the hanging wall of the stope. SLR recommends improving the cable bolt coverage of the stope by drilling the cable bolt holes from a hanging wall access, where the cost can be justified. Additionally, SLR also recommends assessing the production drilling design to reduce the potential for dilution.

 

12.3 Mining Extraction

 

Mining extraction factors for the Vazante Operation are presented in Table 12-4. While Nexa refers to this as mining recovery, SLR’s preference is to refer to this as mining extraction to avoid possible confusion between mining and milling recovery.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Table 12-4:     Mining Extraction Factors

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Method   Long Term     Source     Short Term     Source
Island Pillar     50 %     Historical       50 %     Historical
                               
SLS (VRM)     98 %     Historical                
                               
SLS (OS)     83 %     Historical                
                               
Rib Pillar     60 %     Historical       60 %     Historical
                               
CAF     98 %     Benchmark       98 %     Benchmark
                               
Sill Pillar     35 %     Design                

 

Mineral Reserve tonnage and metal content are affected in direct proportion to variations in extraction.

 

SLR is of the opinion that the mining extraction factors are reasonable. SLR notes that island pillar refers to pillars that are left at the midpoint of a 60 m long stope whereas the rib pillars are located on the ends of the stope block.

 

12.4 Geotechnical and Hydrological Studies

 

Multiple geotechnical and hydrological studies and analysis have been performed to assist in the mine planning process for the Vazante Operation.

 

12.4.1 Geotechnical

 

The methodology for stope design including sublevel intervals, pillar spacing and sizes, and ground support requirements are based on empirical methods. Mine geotechnical personnel collect and record important data that is used in empirical analysis for the design process. The Rock Mass Rating (RMR) is determined using six parameters including:

 

· A1, uniaxial strength of the intact rock.

 

· A2, rock quality designation (RQD).

 

· A3, spacing of discontinuities.

 

· A4, condition of discontinuities.

 

· A5, ground water conditions.

 

· B, orientation of discontinuities.

 

The RMR value is determined by the following equation: RMR= A1+A2+A3+A4+A5+B, and the Modified or Adjusted RMR’ is estimated by applying the factor for the dip of the structure as follows.

 

RMR’= RMR(1-0.4cosØ)

 

Where:

 

Ø is the angle of the hanging wall contact or dip of the structure.

 

Values of the various factors are taken from published tables of data developed over time by various professionals in the field of rock mechanics and used in empirical analysis. For the Vazante Operation rock masses an average RMR value of 47 was estimated and using an average dip of 61° an RMR’ of approximately 40 was determined. These values can be determined for each stope in question to address the varying conditions throughout the underground mine.

 

The Rock Mass Quality Index (Q) was assessed using the parameters summarized in Table 12-5. These values represent the current values used at the Vazante Operation.

 

 

 

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Table 12-5:     Rock Mass Quality

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Value     Dip     RQD     Jn     Jr     Ja     Q'
  High       89       100       15       1       3       3.33
                                                   
  Low       28       13       15       1       2       0.43
                                                   
  Average       61       75       15       1       2       2.48

 

The factors Jn, Jr and Ja refer to joint number, joint roughness, and joint alteration, respectively. These factors allow for the calculation of the Modified Rock Mass Quality Index (Q’) based on the following formula:

 

Q’= RQD/Jn x Jr/Ja

 

The value of Q’ can then be used to evaluate the Stability Number (N’) which enables plotting of the value on a stability graph against the hydraulic radius (Hr), area of the opening divided by the perimeter, of the stope. Stability graphs have been developed over time based on case histories and provide a guide as to whether the opening is in a stable zone, transition zone, or caving zone. These graphs provide guidance in regard to the recommended support to stabilize the opening and control sloughing in order to control the amount of dilution entering the stope excavation.

 

Geotechnical data is also used to determine the factors for N’ as shown in Table 12-6.

 

Table 12-6:     Modified Stability Number

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Value     Factor A     Factor B     Factor C     N'     Hr
  High       1.0       0.3       7.9       7.4       12.5
                                           
  Low       0.9       0.3       2.0       0.8       1.3
                                           
  Average       1.0       0.3       5.1       3.8       5.6

 

N’ is determine using the following formula.

 

N’= Q’ x A x B x C

 

Where:

 

A= is a measure of the ratio of intact rock strength to induced stress.

 

B= is a measure of the relative orientation of dominant jointing with respect to the excavation surface.

 

C= is a measure of the influence of gravity on the stability of the face being considered.

 

A range of values of each of these factors has been developed by various experts and can be used by operating mines in assessing their proper conditions.

 

The rock mass classification for the Vazante Operation is presented in Table 12-7.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Table 12-7:     Rock Mass Classification

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Class   Degree
Alteration
  Degree
Fracturing
  Rock
Quality
  Structural
Pattern
  Lithology   Presence of
Cracks
  Fragmentation
of Blocks
  Recovery
(%)
  RQD
(%)
II-A   A2   F2-F3   V. Good   Slab   Dolomites   No   m3   >95%   >60
                                     
II-B   A2   F2-F3   V. Good   Wedge   Breccia   No   m3   >95%   >60
                                     
III-A   A2-A3   F3   V. Good   Slab   Dolomites   No   dm3 to m3   90% - 95%   50 to 75
                                     
III-B   A2-A3   F3   V. Good   Wedge   Breccia   No   dm3 to m3   90% - 95%   50 to 75
                                     
IV-A   A3   F3-F4   Good/Avg.   NA   NA   cm to dm   cm3 to dm3   >90%   25 to 50
                                     
IV-B   A3-A4   F3-F4   Avg./Poor   NA   NA   cm to dm   cm3 to dm3   75% - 95%   25 to 50
                                     
V   A3-A4   F4   V. Poor   NA   NA   cm to dm   cm3 to dm3   50% - 75%   <25
                                     
VI   A2   F4-F5   V. Poor   Slab   NA   No   cm3 to dm3   >95%   <25
                                     
VII   A4   F4-F5   V. Poor   Filito   NA   m   cm3 to dm3   <50%   <25
                                     
Pillars   Independent assessment                            

 

Figure 12-1 indicates the support chart used to determine the level of support for the heading in question. The example shown is for breccia with a heading dimension of 4.5m x 5.0 m and the coloured dots indicate the minimum (red), average (yellow) and maximum (green) Q values.

 

  

Figure 12-1:     Empirical Support Chart

 

Ground support at the Vazante Operation includes the following, depending on the condition being addressed.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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· Rock bolts, rebar, swellex, split -set bolts of varying lengths up to two metres.

 

· Welded wire mesh,

 

· Cable bolts that are grouted in place (can be tensioned).

 

· Shotcrete (including fibre reinforced) sprayed at various thickness to obtain the required strength.

 

Due to the average dip of the Vazante veins, cable bolting is a prominent support method used and efforts are ongoing to improve the cable bolt pattern designs to help reduce the amount of dilution from the hanging walls of the stopes.

 

An example of the RMR’ and N’ graphs is shown in Figure 12-2 and Figure 12-3.

 

Figure 12-1 provides an estimate of the ELOS, on the stope hanging wall, using the adjusted RMR’ plotted against the stope Hr. Figure 12-2 indicates the location of the low, average, and high N’ and Hr values with respect to cable bolting case histories showing the range for the stable, transition, and caving zones experienced in hard rock mines. These curves reflect the need for good support of the stope hanging walls to help control the amount of slough created. N’ indicates some case histories of cable bolting providing stability, particularly at the average Hr value at the Vazante Operation.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Figure 12-2:     ELOS Graph for Vazante Mine

 

  

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Figure 12-3:     Stope Stability Graph

 

Pillars are also used to control stope dilution. These include the use of sill pillars between mining sublevels, island pillars located at the centre of stopes, and rib pillars positioned at the extremities of the stopes to reduce the potential for excess sloughing from the hanging wall contact and control dilution from adjacent filled stopes. Efforts are being made by Nexa personnel to optimize the design and positioning of the pillars to maximize economic returns. The ELOS is currently assessed by taking measurements using a scanning device such as a CMS in order to enable reconciliation of actual to design values. CMS coverage is currently completed on a monthly basis by geotechnical staff, however, the company has not been able to measure every stope. SLR notes that Nexa personnel are working to maximize the measurements and supports these efforts.

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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The Vazante Operation has a Ground Control Management Plan which details the support mechanisms for the various ground classifications, implementation strategy, and verification through QA/QC. Instrumentation is used to monitor critical excavation areas and critical analysis is carried out on a regular basis. Control of ground vibrations through rigorous blasting design follows industry best practices.

 

In SLR’s opinion the geotechnical data collection and analysis, and ground control designs for the Vazante Operation are adequately addressed by Nexa personnel.

 

12.4.2 Hydrology

 

Nexa uses a FEFLOW ground water model, which was last updated in 2019, as its primary water management tool at the Vazante Operation. Given the extreme dewatering that is required to permit ongoing mining hydrologic monitoring is considered a critical element of operations. Continued calibration of flows is important to predict, plan, and install required pumping capacities for the Vazante Operation. The average dewatering rate has been estimated at an average of 13,000 m³/h to 15,000m³/h.

 

The capacity of the pumping stations at Vazante include the following:

 

· Vazante Mine

 

o 297 Level Station 19,500m³/h

 

o 140 Level Station 10,000m³/h and Phase 2 up to 20,000m³/h

 

· Extremo Norte

 

o 522 Level Station 2,000m³/h

 

o 347 Level Station 1,000m³/h (planned for 2020)

 

o 185 Level Station 1,000m³/h (planned for 2026)

 

The frequency of dolines/sinkholes at Vazante and Extremo Norte mines has been well documented over time and is discussed in further detail in Section 13.4.4 Dolines and Sinkholes of this Technical Report Summary.

 

SLR notes extreme rainfall events and the associated potential temporary flooding of the Santa Catarina River could present a major risk to the underground mining operations.

 

12.5 Cut-Off Value

 

A NSR cut-off value is determined using the Mineral Reserve metal prices, metal recoveries, concentrate transport, treatment, and refining costs as well as mine operating costs. The metal prices used for the for the Mineral Reserves are based on consensus, long term forecasts from banks, financial and other sources.

 

The cut-off value used to calculate Mineral Reserves is based on an NSR value (US$/t processed), which can be directly compared to the mine operating costs. The NSR formula is:

 

 

 

 

 

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The cut-off costs and NSR parameters are summarized in Table 12-8. The breakeven NSR cut-off value was estimated to be $47.49/t processed, which Nexa has indicated is equivalent to a 3.03% Zn cut-off grade excluding any silver or lead credits. SLR considers this appropriate as this includes the contribution of all metals. An incremental cut-off value of $34.55/t is used for certain stopes where the cost of the development to access the ore has been paid for by adjacent mined Mineral Reserves.

 

Table 12-8:      NSR Data

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Item   Units     Value  
Metallurgical Recovery                
Zn     %       82.11  
Pb     %       22.12  
Cu     %       NA  
Ag     %       42.00  
Zn Concentrate Payable     %       85.0  
Pb Concentrate Payable     %       95.0  
Cu Concentrate Payable     %       97.0  
Metal Prices                
Zn     US$/t       2,494.30  
Pb     US$/t       1,956.00  
Cu     US$/t       6,457.90  
Ag     US$/oz       16.85  
Transport Charges                
Zn Concentrate     US$/t conc.       Integrated  
Pb Concentrate     US$/t conc.       278.72  
Cu Concentrate     US$/t conc.       NA  
Treatment Charges                
Zn Concentrate     US$/t conc.       0  
Pb Concentrate     US$/t conc.       142.57  
Cu +RC Concentrate     US$/t conc.       NA  
Refining Charges                
Cu Concentrate     US$/lb          
Ag in Cu Concentrate     US$/oz       NA  
Ag in Pb Concentrate     US$/oz       1.00  
Integrated Zn                
Premium     US$/t       286.31  
Conversion Cost     US$/t       473.95  
Operating Costs                
Mining     US$/t proc.       27.47  
Processing + Maintenance     US$/t proc.       14.57  
General and Administration (G&A)     US$/t proc.       5.45  
Total     US$/t proc.       47.49  

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

  

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SLR notes that the metallurgical recoveries presented in Table 12-8 are averages, however, the NSR calculations use a grade-recovery relationship for each metal based on recent operating performance. Therefore, the NSR factors are variable by head grade, with average NSR factors summarized in Table 12-9. The average NSR factors are calculated using the LOM revenue contribution from each metal net of off-site costs and factors, divided by the reserve grade for that metal, and are indicative of the relative contribution of each metal unit to the economics of the mine. For most metals, a variable recovery (as a function of head grade) was used, and therefore the average NSR factors should not be applied to head grades without considering the head grade versus recovery relationship.

 

Table 12-9:      Average NSR Factors

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Metal   Unit     Value  
Zn     US$/%       17.32  
Pb     US$/%       0.08  
Cu     US$/%       N/A  
Ag     US$/g       0.20  

 

SLR is of the opinion that, except as noted, the parameters and calculations used in the NSR calculation are appropriate. SLR notes that the use of an NSR cut-off grade in what is essentially a single product mine (98% revenue from zinc) is not completely necessary. Vazante Operation geologists may benefit from having the cut-off grade expressed as percent zinc as grade control at the Vazante Operation is predominantly based on visual grade estimation by Vazante Operation geologists.

 

12.6 Reconciliation

 

Ore recovery is currently assessed by taking measurements using a scanning device such as a CMS in order to enable reconciliation of actual to design values. CMS coverage is currently completed on a monthly basis by geotechnical staff, however, Nexa has not been able to measure every stope. SLR notes that Nexa personnel are working to maximize the measurements and supports these efforts.

 

The reconciliation data available for the underground mine is shown in Table 12-10 for the period January 1, 2020 to December 31, 2020

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Table 12-10:      Reconciliation Data

Nexa Resources S.A. – Vazante Polymetallic Operations

 

        Mined       Reserve Model  

Month

    Tonnes
(t)
    Grade
(% Zn)
    Contained Zinc
(t)
    Tonnes
(t)
    Grade
(% Zn)
    Contained Zinc
(t)
 
Jan 2020       101,083       9.54       9,642       89,735       10.59       9,502  
Feb 2020       101,123       11.28       11,407       87,395       12.25       10,705  
Mar 2020       94,909       10.90       10,345       62,115       13.35       8,292  
Apr 2020       99,061       9.51       9,425       76,276       10.82       8,253  
May 2020       114,518       11.26       12,891       95,418       12.10       11,543  
Jun 2020       75,566       9.93       7,504       73,931       11.29       8,347  
Jul 2020       93,321       10.52       9,817       88,382       12.09       10,685  
Aug 2020       93,645       9.19       8,603       105,720       10.03       10,601  
Sep 2020       100,058       10.23       10,240       103,690       10.82       11,224  
Oct 2020       107,789       10.69       11,528       95,951       11.88       11,401  
Nov 2020       96,612       9.91       9,574       101,542       10.87       11,034  
Dec 2020       98,529       12.12       11,945       94,829       13.70       12,991  
2020 Total       1,176,214       10.45       122,920       1,074,984       11.59       124,579  

 

The comparison of the recovered ore to the Mineral Reserve model (as a percentage) is shown in Table 12-11. Results suggest that actual dilution is higher than estimated, as noted above.

 

Table 12-11:      Recovered Compared to Reserve Model

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Month     Tonnes     Grade     Contained Zinc  
Jan 2020       13 %     -10 %     1 %
Feb 2020       16 %     -8 %     7 %
Mar 2020       53 %     -18 %     25 %
Apr 2020       30 %     -12 %     14 %
May 2020       20 %     -7 %     12 %
Jun 2020       2 %     -12 %     -10 %
Jul 2020       6 %     -13 %     -8 %
Aug 2020       -11 %     -8 %     -19 %
Sep 2020       -4 %     -5 %     -9 %
Oct 2020       12 %     -10 %     1 %
Nov 2020       -5 %     -9 %     -13 %

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Month   Tonnes     Grade     Contained Zinc  
Dec 2020     4 %     -12 %     -8 %
2020 Total     9 %     -10 %     -1 %

 

SLR notes that while overall mined tonnage is 9% higher than planned, there is a lower grade tertiary lens of mineralization surrounding the higher grade ore that is being recovered in some of the overbreak areas.

 

SLR considers the efforts put into the record keeping and reconciliation to be of good quality and in accordance with good industry practice. SLR recommends that the reconciliation results and the stope performance analysis be used to evaluate stope designs to determine where improvements in mine planning would be most advantageous.

 

 

 
Nexa Resources S.A.│Vazante Polymetallic Operations, SLR Project No:  233.03245.R0000
Technical Report Summary - February 15, 2021

 

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13.0 Mining Methods

 

13.1 Mine Design

 

The Vazante Operation consists of two mechanized underground mines, the Vazante Mine and Extremo Norte Mine, currently operating at a rate of approximately 1.5 Mtpa. The mineralized zones dip between 45° and 70° and the mine extends over a strike length of five kilometres. With the addition of the North Extension, this will increase to approximately 10 km. The Vazante Mine currently extends over a vertical depth of 300 m from surface to the 326 level. The Vazante Mine is being deepened by 186 m to the planned 140 level. There are former open pits along portions of the strike of the Vazante deposit.

 

There are two access ramps to the Vazante Mine and one to the Extremo Norte Mine. Mine headings range from 5 m high by 4.5 m wide ore drives to 6 m high by 5 m wide main ramps. The average stope widths based on the Measured and Indicated Mineral Resources at 2019 YE are listed in Table 13-1. The thicknesses were examined in the lower, central, and upper portions of the Vazante Mine, with the overall averages shown for the Extremo Norte Mine area. The minimum mining width for Mineral Reserve estimation is stated as four metres. While the mineralization tends to become narrower at depth, the average thickness is between nine metres and ten metres. SLR does not consider the narrow ore widths to be a major issue with respect to the Mineral Reserve estimation, however, SLR recommends that Nexa consider employing smaller mine equipment, particularly load-haul-dump units (LHDs) and production drills in narrow areas if the economics can be justified. Figure 13-1 presents a longitudinal section of the thickness contours.

 

Table 13-1:             Stope Average Widths (2019 YE)

Nexa Resources S.A. – Vazante Polymetallic Operations

 

  Vazante     Extremo Norte  
Widths
(m)
  Vazante
All
    Lower
(Below 225 m)
    Central
(225 m to 326 m)
    Upper
(Above 326 m)
    All
Areas
 
<4     0.2 %     0.1 %     0.0 %     0.1 %     0.0 %
<5     8.4 %     1.4 %     6.1 %     1.0 %     5.2 %
<6     14.3 %     2.5 %     10.3 %     1.5 %     8.5 %
<7     19.8 %     3.2 %     14.6 %     2.0 %     11.3 %
<8     24.2 %     4.0 %     17.8 %     2.3 %     14.0 %
<9     28.6 %     4.8 %     21.2 %     2.6 %     15.7 %
<10     32.6 %     5.1 %     24.6 %     2.8 %     17.9 %
>10     68.1 %     8.3 %     54.8 %     5.0 %     31.9 %

 

 

 
Nexa Resources S.A.│Vazante Polymetallic Operations, SLR Project No:  233.03245.R0000
Technical Report Summary - February 15, 2021

 

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Figure 13-1:          Mine Longitudinal Section Showing Resource Thickness Contours

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

13-2 

 

 

 

 

The Vazante Operation is designed based upon mechanized longitudinal longhole stoping for areas with a dip in excess of 45°. Longhole stopes are developed with footwall access drives parallel to the orebody. Crosscuts are driven from the footwall drive and then the ore is developed along strike. Sublevels are typically 30 m apart though the distance varies depending on the orebody. Long holes are often a combination of downholes or VRM and uppers or sublevel longhole open stopes (SLOS). Both longhole methods employ a retreat sequence along strike. The SLOS stopes are not backfilled where the VRM stopes are backfilled.

 

SLR completed a compilation of the dips by taking vertical slices through each of the zones and tabulating the range of dips as indicated in Table 13-2.

 

Table 13-2:               Range of Mineralization Dips

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Zone   Strike Length
(m)
    Dip Range
(°)
    Dip Average
(°)
 
Lumiadeira SW     875     38-50       45  
Lumiadeira NE     1,620     45-90       62  
Lumiaderia Total     2,495     38-90       55  
Sucuri SW     2,880     38-77       54  
Extremo Norte     1,100     46-70       61  
Extremo Norte     680     37-44       41  

 

The overall average dip on the mineralized zones is 54°. As indicated in Table 13-2, most of the mining can be effectively planned using bulk longhole methods.

 

Ore is mucked with 5 m³ (12.5 t) LHDs working manually when possible (brow full of muck) and on remote control for mucking in the stope (non-man entry conditions). Ore is loaded into 30 t articulated haul trucks at the stope and hauled to surface stockpiles located at the portal. Oversize material is placed aside in a separate stockpile and secondary breaking is carried out with mechanical rockbreakers.

 

Mechanized cut and fill mining is planned for the shallower dipping ore zones, though these areas are not yet reflected in the Mineral Reserves. The stopes will be accessed by a ramp and the ore will be mined using, four to five metre high, horizontal cuts drilled with a jumbo and the ore hauled to surface. After each lift, the void will be filled with waste rock fill and the subsequent cut will be started along the strike length of the stope.

 

13.2 Mining Method

 

The Vazante Operation is in production with ongoing operations and development. The projected mine life is expected to continue to the end of 2031.

 

The Vazante Mine extends over a five kilometre strike length with planned heading extensions to the Extremo Norte zone. Currently, the Extremo Norte Mine operates independently of the Vazante Mine, however, there are plans to connect the Vazante Mine workings to the Extremo Norte workings.

 

 

 
Nexa Resources S.A.│Vazante Polymetallic Operations, SLR Project No:  233.03245.R0000
Technical Report Summary - February 15, 2021

 

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13.2.1 Longhole Stoping

 

Longhole mining methods are employed for the major portion of the total Mineral Reserves at the Vazante Operation for stopes with a dip in excess of 45°. Levels and haulage drifts are designed to run parallel to, and in the footwall of, the mining blocks. Levels to access longhole stopes are spaced at a vertical interval of approximately 30 m. Crosscuts from the footwall access are generally 70 m along strike.

 

Both up hole and downhole drilling is carried out. Sill pillars are left as required above an area drilled with up holes. These pillars can be recovered using downholes from the level above. Schematic longhole stope configurations are shown in Figure 13-2. The mining sequence for the VRM longhole stopes is indicated in Figure 13-3.

 

Sill pillars are left after every second level and are designed to be ten metres in height. There are plans for the recovery of part of these pillars. SLR recommends a review of increasing sill pillar recovery as a potential future opportunity.

 

Rib pillars ten metres wide are included along strike between every 60 m long stope section. These rib pillars are partially recovered at the completion of the stoping, with a planned recovery of six metres of the rib pillar. The rib pillars serve only to retain the rock fill in adjacent stopes.

 

Longhole drilling is carried out using Simba longhole drills on up holes and downholes. Drill holes are up to 10 cm in diameter, drilled on rings spaced 2.4 m apart, and with holes spaced two metres apart on each section. The Vazante Operation has four Simba production drills in the drilling fleet with productivities averaging 20 m/h. The fleet includes one in-the-hole (ITH) drill and three top hammer type longhole drills providing the stope drilling requirements. SLR understands that the hole locations are to a large extent dictated by the longhole drill and that the Simba carrier size can limit the drill collar location and the drill hole orientation. In SLR’s opinion, long hole drill layouts should be subjected to review to minimize the potential damage to the hanging wall and to obtain the best fragmentation. In areas where the mineralization is four metres wide or less, it may be preferable to acquire a smaller longhole drilling unit that is better suited to working in narrow areas. A smaller sized LHD should also be considered to permit mining closer to the actual vein geometry, which will significantly improve ore recoveries.

 

SLR recommends that narrow vein equipment be assessed as soon as possible to have it readily available at the time narrower areas are encountered in the lower mine.

 

SLR recommends completing a trial test stope using a smaller drill unit in the upper section of the Vazante Mine to assess the efficacy and optimize the drilling layouts, as a prerequisite to eventual application of the method on a larger scale in the lower levels of the mine, when a larger portion of the mine production comes from this area.

 

SLR observed secondary breaking on surface during the 2018 site visit. SLR recommends that the stope drill patterns be reviewed with the intent of reducing the level of stope dilution through adjustment of the drill pattern. This may require drilling an additional hole on the hanging wall contact, between the current burden spacing. A reduced explosive charge per hole, using a lower density explosive, would aid to effectively trim the hanging wall contact thereby providing a much cleaner break. The reduced blast vibration impact (a lower peak particle velocity (ppv)) would lead to a lower degree of overbreak on the hanging wall and less dilution.

 

 

 
Nexa Resources S.A.│Vazante Polymetallic Operations, SLR Project No:  233.03245.R0000
Technical Report Summary - February 15, 2021

 

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Figure 13-2:            VRM and SLOS Longhole Stope Layouts

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Figure 13-3:          VRM Longhole Stope Sequence Schematic

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

13-6 

 

 

 

 

13.2.2 Cut and Fill Stoping

 

Cut and fill mining will be used for a small portion of the Vazante Operation production and this will be mostly towards the latter years of the LOM plan. These areas have not been included in the current Mineral Reserves.

 

Dilution will be an issue in the narrow cut and fill stopes as the four metre minimum mining width will impact upon every lift taken. SLR recommends that a stope width review be carried out for the planned cut and fill stopes to determine whether the current equipment fleet matches the orebody dimensions.

 

SLR recommends evaluating the use of a “shanty back” configuration on the hanging wall side of the drift to reduce dilution.

 

A schematic view of cut and fill mining and the necessary ramp development is shown in Figure 13-4.

 

 

 
Nexa Resources S.A.│Vazante Polymetallic Operations, SLR Project No:  233.03245.R0000
Technical Report Summary - February 15, 2021

 

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Figure 13-4:               Cut and Fill Stoping Schematic

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

13-8 

 

 

 

 

13.3 Life of Mine Plan

 

Table 13-3 summarizes the LOM reserve plan for the years 2021 through 2031, although SLR notes that the continued conversion of Mineral Resources to Mineral Reserves will likely extend the mine life.

 

Metal production over the LOM includes 1.21 Mt Zn, 17,900 t Pb, and 3.1 Moz Ag. The net metal recoveries are on average 83.54% for zinc, 47.2% for lead, and 42.0% for silver in the lead concentrate.

 

Table 13-3:               LOM Production

Nexa Resources S.A. – Vazante Polymetallic Operations

 

        Grade   Recovery   Recovered Metal
Year   Tonnes
(000 t)
  (% Zn)   (% Pb)   (g/t Ag)   (% Zn)   (% Pb)   (% Ag)   Zn
(000 t)
  Zn Con
(000 t)
  Pb
(000 t)
  Pb Con
(000 t)
  Ag
(000 oz )
2021   1,520   10.36   0.26   17.4   85.97   47.2   42.0   135   347   1.9   7.6   357
2022   1,520   9.83   0.29   16.2   85.29   47.2   42.0   128   327   2.1   8.3   332
2023   1,530   9.75   0.25   16.6   85.19   47.2   42.0   127   326   1.8   7.1   344
2024   1,536   9.77   0.22   14.6   85.21   47.2   42.0   128   328   1.6   6.4   303
2025   1,530   9.79   0.21   15.1   85.23   47.2   42.0   128   327   1.5   6.1   311
2026   1,536   9.75   0.27   15.6   85.19   47.2   42.0   128   327   1.9   7.7   323
2027   1,536   7.68   0.21   10.4   82.28   47.2   42.0   97   249   1.5   6.1   215
2028   1,540   7.66   0.20   13.1   82.25   47.2   42.0   97   249   1.4   5.7   272
2029   1,531   6.83   0.22   13.3   80.97   47.2   42.0   85   217   1.6   6.3   274
2030   1,513   6.90   0.21   11.1   81.08   47.2   42.0   85   217   1.5   6.1   227
2031   1,391   6.18   0.17   7.2   79.92   47.2   42.0   69   176   1.1   4.6   135
Total   16,684   8.61   0.23   13.74   83.89   47.2   42.0   1,205   3,090   17.9   71.8   3,094

 

The planned mine development over the LOM totals approximately 17.5 km per year from 2021 through 2026 followed by a ramp down and finally, ceasing by 2030. The production rate and head grades are presented in Figure 13-5 and the development profile over the LOM is presented in Figure 13-6. These figures also indicate the actual production and development rates from 2008 to 2019 followed by the LOM planned rates until the year 2031.

 

 

 
Nexa Resources S.A.│Vazante Polymetallic Operations, SLR Project No:  233.03245.R0000
Technical Report Summary - February 15, 2021

 

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Figure 13-5:         Mine Production Profile for LOM

 

 

Figure 13-6:         Mine Development Profile for LOM

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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13.4 Infrastructure

 

The Vazante Operation underground mine infrastructure comprises electrical substations spaced at various levels to provide power distribution for the mine equipment. Underground dewatering infrastructure includes the main mine sumps with the mine dewatering system requiring approximately 16 MW, or over 50% of the total mine site power demand.

 

Equipment maintenance is carried out in surface maintenance facilities as underground maintenance facilities are not required at the present time.

 

The Vazante Operation employs the “Smartmine UG” system which helps control all underground operations by monitoring the fleet with on-board computers and by tracking the progress of all tasks. Monitoring is performed through a dispatching interface in near real time, using data communication infrastructure and positioning technology. Smartmine UG is intended to deliver advanced production management, process control, mine-face cycle management, and fleet key performance indicators (KPI) in a unique 3D environment.

 

Underground communications are provided through a leaky feeder system allowing for effective communications.

 

13.4.1 Mine Access

 

All mine access is via ramp declines with two at the Vazante Mine and one at the Extremo Norte Mine. The Extremo Norte and Vazante mines will eventually be connected for one continuous ten kilometre strike length. Two shafts exist primarily for dewatering access ways. Shaft number one is five metres in diameter providing access to the dewatering pumping stations and is equipped with a hoist and cage system to move men and materials. The second shaft extending down to the 140 m level provides access to the pumping station and emergency egress from the area.

 

13.4.2 Mine Deepening Project

 

The two phase Mine Deepening Project (MDP) at the Vazante Operation commenced with engineering in 2013 and start of mine development in early 2017. Phase I installation was completed in 2019, providing the current capacity of 10,000 m³/h from the 140 level pump station. The Phase II development is underway with the capacity increase to 15,000 m³/h to be completed in 2022.

 

The MDP is shown in the schematic diagram in Figure 13-7. The figure also shows the lateral extent of the mine including the Extremo Norte portion, which has pump stations with 2,000 m³/h pumping capacity on the 522 level and 1,000 m³/h pumping capacity on the 347 and 185 levels.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Figure 13-7:         Mine Deepening Project Longitudinal Section

 

13.4.3 Mine Dewatering

 

Mine water is collected and directed to the drainage gallery on the 326 level. Water flows along the drainage gallery to the 30,000 m³ capacity sump located next to the pump station on the 297 level. The pump station consists of twelve centrifugal pumps operating in parallel with a total capacity of 16,000 m3/h, plus a secondary two-stage pumping station (PS300-PS500) with a total capacity of 3,500 m³/h. The two pumping stations combined have a total capacity of 19,500 m³/h. The permitted pumping limit for the Vazante Mine is 19,823 m³/h. The permitted pumping limit for the Extremo Norte Mine is 2,000 m³/h. The combination of the Vazante and Extremo Norte mine dewatering limits represent the permitted maximum pumping flow rates in the lowest level drainage gallery to the sump. The pump station has a shaft to surface access and the pump station can be isolated from the mine by a hydrostatic door in case the pumps are not operating. The contingency plan is to seal the pump station and allow the lower parts of the mine to flood. Mine water from the Vazante Mine is pumped to the tailings area and treated flow from the tailings area flows to the Santa Catarina River below the Aroeira TSF.

 

Dewatering at the Vazante Operation is a critical aspect of the mine operation as a high rate of dewatering is required to enable mining to be carried out in a safe and efficient manner on a continual basis. The FEFLOW groundwater model was reviewed in 2019 in a report by Water Services and Technologies Ltda. (WST), from Belo Horizonte, Brazil. The 2018 model predicted dewatering flow rates as presented in Figure 13-8 with the contribution from the various areas of the Vazante Operation.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Figure 13-8:         Mine Dewatering Rate

 

Figure 13-9 presents the Vazante Mine rainfall and mine pumping rate over time from 1990 to 2020 with the most recent annual rate at approximately 12,500 m³/h, well within the installed pumping capacity of the Vazante Mine. The Extremo Norte Mine has a current pumping rate of approximately 300 m³/h, well above the installed capacity.

 

 

Figure 13-9:         Historical Rain and Dewatering Rates

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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SLR also reviewed the dewatering rate as a function of the total cumulative mine development, taking the mine development as a measure of the volume to be dewatered, the results of which are shown in Figure 13-10.

 

The pumping rate from 2019 to 2020 increased by approximately 5%. As indicated in Figure 13-10, a projected 5% increase per year would achieve the 20,000 m³/h rate of pumping capacity by the year 2027. Figure 13-10 shows the planned development on a cumulative basis per year until 2039.

 

SLR recommends that a review of the dewatering capacity be completed on an ongoing basis as development advances and actual dewatering rates dictate, to ensure that, if required, additional capacity can be installed in a timely manner.

 

 

Figure 13-10:         Cumulative Development versus Pumping Rate

 

Figure 13-11 presents the extent of the mine workings and the current and projected water table levels up to the year 2033. The WST report provided a simulation of the water table levels and potential impact on the town of Vazante located near the Vazante Operation. SLR recommends that the water table levels be monitored as planned to help foresee any potential issues and assess mitigation measures that may be required.

 

Nexa has installed water gauge stations, piezometer stations, and rain stations in various locations to collect monitoring data on a continuous basis.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Figure 13-11:         Mine Longitudinal Section Showing Extent of Mine Workings and Water Table Levels

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

13-15

 

 

 

 

13.4.4 Dolines and Sinkholes

 

Nexa maintains a record of all dolines and sinkholes that occur on the Vazante Operation property. A document of Karst Risk Management Standards was developed and is used by Nexa personnel to assess and track potential risks from these occurrences. Support is also provided by external consultants for specialized advice for risk management such as development of doline/sinkhole risk maps.

 

The risks identified by Nexa include mine flooding by karst features, inflow from the Santa Catarina River due to overflow, intense rainfall events, and subsidence from doline/sinkhole formations. These are managed through operational procedures such as mapping of fractures and features in efforts to limit rapid water drawdown as the mine is advanced.

 

The sinkholes registered from 2006 to July 2020 are shown in Figure 13-12 and include new, reactivated, and old sinkholes. Since 2006, 616 new, 343 reactivated, and 492 old sinkholes have been registered, for a total of 1,451. A total of approximately 2,400 sinkholes have occurred since 2001 and their locations are shown in Figure 13-13. The occurrences of dolines/sinkholes are closely monitored, and mitigation measures are in place and being constantly reviewed by Nexa and specialized consultants.

 

 

Figure 13-12:         Registered Sinkholes (January 2006 to July 2020)

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

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Figure 13-13:         Registered Sinkholes (2001 to 2020)

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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13.4.5 Backfilling

 

Backfilling at the Vazante Operation consists of loose waste rock fill at the current planned rate of approximately 10,000 t per month. Since there are not always empty stopes ready for backfill material, three stockpile areas are available on surface with a total capacity of approximately 4.6 million cubic metres (Mm3), as listed below:

 

· Bocaina – located at the ramp 07 portal, capacity 1.8 Mm3.

 

· Sucuri – located at the ramp 10 portal, capacity 1.8 Mm3.

 

· Extremo Norte - located at the ramp 01 portal, capacity 0.97 Mm3.

 

SLR is of the opinion that in certain cases, there could be value in considering the use of cemented rock fill (CRF) to enable mining of certain pillars where this is economical. A trade-off analysis would be required in each particular case.

 

13.4.6 Ventilation

 

The Vazante Operation ventilation system uses main exhaust fans to draw fresh air into the mine through the access ramps and exhausts via the main exhaust raises. The average air flow totals are indicated in Table 13-4. The mine ventilation system airflow is planned using the Vouma 3D ventilation design software.

 

Table 13-4:          Mine Ventilation Air Flow

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Vazante Main Mine             Extremo Norte  
Upcast     Flowrate
(m³/s)
      Downcast       Flowrate
(m³/s)
    Upcast     Flowrate
(m³/s)
 
Lumiadeira 1     157       Ramp 10       187     Shaft     120  
Lumiadeira 2     180       Ramp 07       164.2              
Sucuri 1     92.8       Ramp 01       2.5     Downcast        
Sucuri 2     122       Shaft 1       74.2     Ramp     120  
Sucuri 3     270       Shaft 2       81.2              

 

The ventilation circuit needs to comply with Brazilian National Regulation NR 22, which is based on the greatest of the following criteria:

 

· Maximum number of equipment with diesel engines.

 

· Explosives consumption in the mine.

 

· Monthly production tonnage.

 

· Number of mine headings in production.

 

The ventilation circuit design includes consideration of the maximum air speed for different heading types, friction factors for headings, and estimates for losses due to leakage. The key driver for the ventilation requirement is the ventilation quantity required for the diesel equipment. Airflow requirements for diesel equipment are set based upon the engine horsepower. The LOM mine airflow for the Vazante and Extremo Norte mines are shown in Figure 13-14 and Figure 13-15, respectively.

 

 

 

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The Vazante Operation is ventilated using exhaust fans on raises. There are four 2.4 m diameter raises and a three metre diameter raise at the Vazante Mine. The fresh air enters the mine via two five metre diameter air shafts, a 2.4 m diameter raise, and three access ramps.

 

In the Extremo Norte Mine area, there are two three metre diameter exhaust raises, a three metre diameter intake raise, and a single access ramp for fresh air intake.

 

 

Figure 13-14:         Vazante LOM Airflow

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Figure 13-15:      Extremo Norte LOM Airflow

 

The ventilation schematic diagram for the Vazante and Extremo Norte mines is presented in Figure 13-16.

 

 

 

Figure 13-16:      Mine Ventilation Schematic Diagram

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000 

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13.5 Mine Equipment

 

The Vazante Operation has a fleet of mobile equipment to enable development and production activities to be completed in an efficient manner while meeting all mine regulatory requirements for underground mining operations. Table 13-5 lists the major equipment required to sustain the mine production rate. There is also miscellaneous support equipment for various surface operations and other services required by the mine.

 

Table 13-5:      Mine Equipment

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Equipment   Supplier   Model   Units
Trucks   Volvo   A-30   15
             
LHD   Cat   R-1700G   8
             
Jumbo Drills   Epiroc   282   5
             
Prod. Drills   Epiroc   Simba   4
             
Bolter   Epiroc/Sandvik   235S/321 7C   4
             
Cable Bolter   Sandvik   D421   2
             
Shotcrete   Normet   6050 WPC   2
             
Scalers   BTI   DS20   7
             
Scissorlift   Normet/Dux   MF540   5
             
Transmixer   Normet   MF500   2
             
Grader   Cat.   120K   2
             
Trucks Service   Mercedes/Ford   Misc.   15
             
Excavator   Cat / Volvo   416C/BL70   3
             
Raise Bore   Redpath       1

 

Equipment replacement and rebuilds over the mine life will be significant with approximately $53.9 million in capital expenditures as some of the equipment is aging.

 

The availability and utilization factors for the major equipment is shown in Table 13-6. The mine equipment maintenance is carried out on surface in shops that are well equipped.

 

The light vehicles are generally four wheel drive diesel powered compact pickups. Many of the service and flat deck trucks are single axle Ford and Scania trucks.

 

Table 13-6:      Equipment Statistics

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Equipment   Availability
(%)
  Utilization
(%)
Trucks   78   74
         
LHD   69   62

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000 

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Equipment   Availability
(%)
  Utilization
(%)
Jumbo Drills   65   40
         
Prod. Drills   62   50
         
Bolter   61   35
         
Cable Bolter   52   41
         
Shotcrete   48   20
         
Scalers   59   52
         
Scissorlift   76   43
         
Grader   77   64

 

The Vazante Operation uses a combination of Nexa employees and external contractors. Table 13-7 lists the personnel requirements for the operations.

 

Table 13-7:      Personnel

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Category   No. of Personnel
Mine    
     
Permanent Employees   620
     
Contractors   83
     
Plant    
     
Permanent employees   215
     
Contractors   89
     
General & Administrative    
     
Permanent employees   89
     
Contractors   192

 

13.5.1 Ore and Waste Handling

 

Ore is all mucked by LHDs and hauled in trucks to stockpiles located at the portals where the ore is sorted by grade. Ore is hauled from the stockpiles to the crushers by surface haul trucks. Oversize material is separated out and secondary breaking is carried out using a rock breaker unit on an excavator.

 

Trucks are weighed on scales that are located close to the main access ramps at both the Vazante and Extremo Norte mines.

 

Waste, from development, is either dumped into stope voids or hauled to surface.

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000 

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14.0 Processing and Recovery Methods

 

14.1 Summary

 

The Vazante Operation processing facilities have a nominal design processing capacity of approximately 4,400 tpd or 1.6 Mtpa at 96% utilization and produce approximately 350,000 tonnes per annum (tpa) to 370,000 tpa of zinc concentrate and approximately 4,000 tpa to 5,000 tpa of lead concentrate that contains small amounts of silver. They consist of two adjacent plants, Plant C and Plant W, that are interconnected at various points. The key unit process steps are presented in the block flow diagram in Figure 14-1. In 2020 the Vazante Operation processed 1.62 Mt at an averaged head grade of 10.4% Zn and 0.36% Pb. Zinc concentrate produced at the Vazante Operation is sent to Nexa’s Três Marias zinc smelter approximately 250 km from Vazante.

 

Processing at the Vazante Operation comprises conventional crushing, grinding, flotation, concentrate dewatering, and tailings disposal. The main differences between the two plants is that Plant W incorporates a sulphide flotation stage for the recovery of a lead–silver concentrate. Both plants include crushing, grinding, and zinc flotation. Combined Plant W and Plant C tailings are thickened and filtered prior to disposal in the Pilha Garrote DSTSF. Figure 14-2 presents a simplified flowsheet for the plants.

 

Plant C is an older plant with an approximate capacity of 47 tonnes per hour (tph) that was historically used for the treatment of calamine ore and was subsequently converted to treat willemite ore. Plant C processes approximately 25% of the total processed tonnage. Conversely, Plant W is a modern plant, commissioned in 2003, with a capacity of approximately 145 tph. Ground ore from both plants is combined and processed through an initial bulk sulphide flotation, and the tails from the sulphide flotation are split between the two willemite flotation circuits. The sulphide circuit produces a lead–silver sulphide concentrate that is elevated in zinc. Zinc production in the sulphide circuit accounts for < 1% of total zinc production. Zinc in the willemite concentrate provides the primary revenue, while lead, silver, and zinc recovered in the bulk sulphide concentrate provide a minor by-product credit. In 2012, the Plant W sulphide circuit was added, prior to this there was no means to recover a separate lead-silver sulphide concentrate, and these metals were discarded with the tailings.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000 

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Figure 14-1:       Process Block Flow Diagram

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Figure 14-2:       Simplified Process Flow Sheet

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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14.2 Plant C

 

Run of mine (ROM) ore is crushed in a three-stage crushing circuit in closed circuit with screens to 98% passing 9.5 mm. ROM ore is dumped into a silo and fed to the primary jaw crusher, which discharges onto a primary double deck vibrating screen. The top deck has a 38 mm aperture screen, and the bottom deck is a 16 mm x 14 mm aperture screen. Material retained on the top deck reports to two secondary jaw crushers, while material retained on the bottom deck feeds the tertiary cone crusher. The product of both secondary jaw crushers is returned to the primary vibrating screen. The primary vibrating screen bottom deck undersize is combined with the tertiary crusher discharge, which then forms the overall product from the Plant C crushing plant. This crushed ore is stored in a covered conical pile of up to 4,000 t capacity.

 

Crushed ore is reclaimed by FEL and fed to the Plant C grinding circuit, which consists of a 2.4 m diameter x 11 m effective length ball mill in closed circuit with three hydrocyclones. The target grind size is approximately 88% passing 150 μm. Grinding circuit product is pumped to Plant W for sulphide flotation. Sulphide flotation tails are then split, and a portion returns to Plant C where they are pumped to a conditioning tank where a sodium sulphide activator, dispersant, and amine collector are added to prepare willemite for flotation. The conditioned slurry is then processed in the zinc rougher circuit, which consists of four 8.5 m3 forced air flotation cells. Rougher concentrate is processed in the Plant C zinc cleaner cells. Cleaner concentrate is combined with the Plant W rougher concentrate to form the final zinc concentrate, while cleaner tails report to the cleaner scavengers. Cleaner scavenger concentrate is either returned to the cleaner feed or reports to the final zinc concentrate. The rougher tail is directed to the zinc scavengers, which have four 8.5 m3 cells. The scavenger concentrate recirculates to the rougher feed. Scavenger tails are then combined with the Plant W rougher scavenger tails and pumped to the tailings thickener.

 

14.3 Plant W

 

ROM ore is crushed in a four-stage crushing circuit in closed circuit with screens to 98% passing 9.5 mm. Crushed ore is homogenized on a stockpile with a capacity of approximately 6,000 t by a stacker-reclaimer before being fed to the Plant W grinding circuit, which consists of a ball mill in closed circuit with a high frequency vibrating screen. The screen undersize is approximately 88% passing 150 μm (P80 of approximately 125 μm) and is directed to two conditioning tanks in series prior to feeding the Plant W sulphide flotation circuit.

 

The sulphide (lead–silver) flotation circuit uses methyl isobutyl carbinol (MIBC) frother, sodium sulphide activator, and potassium amyl xanthate collector (PAX). The Plant W circuit includes lead roughing and scavenging using three and two 70.0 m3 FLSmidth tank cells, respectively. Scavenger concentrate is recycled to rougher feed, while lead scavenger tails are split and the larger portion reports to the Plant W zinc flotation circuit while the remainder reports to the Plant C zinc flotation circuit. Rougher concentrate is treated in the first cleaner stage, which consists of two 10.0 m3 FLSmidth tank cells. The first cleaner tail reports to the lead first cleaner–scavenger, with the lead first cleaner–scavenger concentrate returning to the lead first cleaner and lead first cleaner–scavenger tailings returning to lead rougher feed. The lead first cleaner is followed by a second cleaner stage, which consists of one 5.0 m3 FLSmidth tank cell in closed circuit with the first cleaner. There are two additional cleaning stages in closed circuit with each other, the third and fourth cleaners, which each consist on one 0.5 m3 FLSmidth tank cell. Third cleaner tailings report to a two-stage lead third cleaner–scavenger consisting of six 0.5 m3 FLSmidth tank cells. The first two cells produce a third cleaner–scavenger concentrate that returns to the third cleaner feed, while the last four cells recirculate their concentrate to the first two cells. Tailings from the third cleaner–scavenger return to the lead first cleaner. The fourth cleaner produces the final lead concentrate, which is dewatered using a pressure filter to produce a filter cake with approximately 10% moisture. Lead concentrate is loaded onto trucks for delivery to customers. The lead cleaner circuit also included a small lead regrind mill, however, this mill was decommissioned in 2016.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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The Plant W zinc circuit recovers a willemite concentrate from the lead scavenger tailings, or the grinding circuit screen undersize during periods when the lead circuit is bypassed. The zinc flotation feed is conditioned with a sodium sulphide activator, dispersant, and amine collector in a single conditioning tank. The first stage of flotation is the zinc roughers, which consist of nine 14.2 m3 forced air flotation cells. Rougher concentrate combines with Plant C zinc rougher concentrate to form the final zinc concentrate. Rougher tailings are pumped to the zinc first scavenger circuit, which has five 14.2 m3 forced air flotation cells. The first scavenger concentrate is recirculated to the zinc rougher feed. The zinc first scavengers are followed by the zinc second scavengers, consisting of an additional four 14.2 m3 cells. Second scavenger concentrate reports to Plant C flotation feed, while zinc second scavenger tailings are pumped to the tailings thickener for dewatering and disposal together with the Plant C rougher scavenger tails.

 

14.4 Zinc Concentrate Dewatering

 

Zinc concentrates from Plant W and Plant C are combined and stored in stock tanks. The combined rougher concentrates may be fed to a single G cell. The G cell, when operational, floats carbonate from the zinc rougher concentrates. This produces a low grade zinc bearing carbonate concentrate, which can sometimes be treated separately at the Três Marias smelter. When produced, this low grade concentrate is stored and dewatered in the low grade G cell pond. The final zinc concentrate is the combined Plant W and Plant C concentrates when the G cell is bypassed, or the G cell tailings when the G cell is operational. Operation of the G cell was suspended in early 2017 and is assumed not to operate in the LOM mill production plan. Final zinc concentrate is thickened in a 16 m diameter Dorr Oliver-Eimco concentrate thickener. Thickener overflow is recycled to process water, while thickener underflow is pumped to hydrocyclones. The coarser underflow is dewatered in three vacuum drum filters, while the finer overflow is dewatered in one Andritz plate and frame pressure filter. The combined cake produced contains approximately 13% moisture.

 

14.5 Tailings Dewatering

 

Combined Plant W and Plant C tailings are combined and pumped to tailings cyclones, thickener, and filters where the tailings are dewatered before being hauled to the Pilha Garrote DSTSF. Coarse cyclone underflow is hauled to the Pilha Garrote DSTSF, while cyclone overflow is thickened in the tailings thickener prior to being filtered. Overflow from the tailings thickener and filtrate are directed to the water pond within the Aroeira TSF and is then recycled in the grinding and flotation plants. Thickener underflow is filtered before being hauled to the Pilha Garrote DSTSF.

 

14.6 Concentrate Handling

 

Filtered lead concentrate is held in a small concentrate stockpile at the process plant prior to being loaded into bulk bags and onto trucks for transport to customers. Filtered zinc concentrate is stored in a zinc concentrate silo prior to being loaded into trucks for transport to the Três Marias smelter. Zinc concentrate in excess of the silo capacity can be stored in a covered stockpile and then reclaimed by FEL to be loaded into trucks.

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000 

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14.7 Concentrate Sales and Processing

 

Zinc concentrate is trucked in bulk approximately 250 km to the Três Marias smelter. The Três Marias smelter circuit leaches concentrate from the Vazante Operation through an autoclave with recycled leach solutions to dissolve carbonates. This is primarily to remove MgO, which can affect electrolysis efficiency. Zinc silicate is then leached with sulphuric acid to zinc sulphate, with chemistry controlled to precipitate silica. The zinc bearing solution is then purified and zinc is recovered by electrolysis. Fluorine levels in leach solutions must be controlled to avoid problems with stripping zinc cathodes in the electrolytic cell house. The Três Marias smelter relies on treating a balance of sulphide concentrates that, when roasted, generate the sulphuric acid that is used to leach the concentrates. The Vazante Operation concentrate makes up approximately 70% of the feed to the Três Marias smelter. Overall zinc recovery from the Vazante Operation concentrate at Três Marias is 94.4%. The conversion costs of the Vazante Operation concentrate are projected at $474/t recovered zinc.

 

Lead concentrate is loaded into bulk bags at the Vazante Operation and transported approximately 900 km to the Port of Itaguai for shipment. Concentrate is sold in 200 t to 600 t shipments, depending on production quantities.

 

14.8 Energy, Water, and Process Materials Requirements

 

Power for the Vazante Operation is supplied from the national grid, which can provide up to 55 MW via two transmission lines. Power requirement for the operations is not expected to exceed 46 MW (for the mine and processing plants) for the remainder of the LOM.

 

Water from concentrate and tailings dewatering is recycled to the process via the Aroeira TSF, which is used as a water storage facility. Make-up process water is sourced from the Santa Catarina River and pumped to the processing plant. With the conversion to dry stack tailings disposal, the amount of water available for recycle to the processing plant is expected to increase.

 

Process consumables include:

 

· Forged grinding media for the ball mills

 

· PAX (sulphide flotation circuit collector)

 

· MIBC (frother)

 

· Sodium sulphide (willemite activator)

 

· Sodium carbonate (pH modifier)

 

· AGLP 250 (dispersant)

 

· Amine willemite collector

 

· Flocculant

 

14.9 Manpower

 

The processing plant personnel comprises management and supervisory staff, including metallurgical personnel, operators, and maintenance personnel, totalling 304 people. This number is made up of 215 permanent employees and 89 contractors and is not anticipated to change significantly in the foreseeable future.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000 

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15.0 Infrastructure

 

15.1 Infrastructure

 

The Vazante Operation is immediately adjacent to a public highway and situated approximately 8.5 km from the town of Vazante. Site access is via paved roads to the mine office.

 

The Vazante Operation surface infrastructure is presented in Figure 15-1 to Figure 15-4, with the main access portals, ventilation raise breakthroughs to surface, surface plant, administration, and tailings facilities, and ancillary installations such as the air strip indicated.

 

15.1.1 Yards and Roads

 

The roads and yards to and in the vicinity of the administration offices area are all paved. The paved sections are regularly cleaned to remove the mud and dirt brought in by vehicles coming from the mine roads. The yards are well maintained and there are sidewalks in all areas.

 

15.1.2 Power

 

Electrical power is supplied from the national grid via two independent transmission lines at 138 kV, which can provide up to 55 MW. There are two 23/40 MVA transformers in the surface substation at the Vazante Operation and power is distributed to other areas of the mine at 13.8 kV and 440 V via transformer secondaries to power mine equipment. The power demand by 2026 is expected to reach approximately 46 MW as dewatering demands continue to grow. A new transmission line from Paracatu to Vazante of 60 MW capacity is under construction by Companhia Energética de Minas Gerais S.A (CEMIG) and is expected to be completed in March 2021. There are two 700 kVA diesel generators on site to provide backup power in case of main line interruption. The price of electrical energy is budgeted at R$0.277/kWh.

 

15.1.3 Mine and Process Water

 

The Vazante Mine generates a significant amount of water that is pumped to surface for discharge. The dewatering capacity of the Vazante and Extremo Norte Mines has been increased to approximately 20,000 m³/h. The main pump rooms on the 297 Level and 140 Level have been designed to handle this quantity. Process water is obtained from the Santa Catarina River and pumped to the processing plant.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000 

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Figure 15-1:     Vazante Mine Surface Infrastructure

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000 

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Figure 15-2:       Site Plan

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000 

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Figure 15-3:    General Site Layout, Process Plant Area

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000 

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Figure 15-4:      General Site Layout, Administration Area

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000 

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15.1.4 Aroeira Tailings Impoundment Area

 

Tailings from the process plant were regularly deposited in the Aroeira TSF, a conventional slurried tailings storage facility located immediately below the processing plant, until mid-2019. Tailings from the plant flow by gravity to the TSF. The Aroeira TSF remains in operation for the collection of underground mine dewatering and as the water supply storage dam for the processing plant. The Aroeira TSF is also used for tailings disposal when the infrastructure of the new facility (i.e., Pilha Garrote) is temporarily down for maintenance. Nexa informed SLR that approximately 30% of the tailings production in 2020 was deposited in the Aroeira TSF. Water is reclaimed from the Aroeira TSF pond to the processing plant via a floating barge and pump.

 

The Aroeira TSF was the primary operating TSF until 2019 and was designed by Geoconsultoria with construction commencing in 1999 and operation in January 2001. The initial cross valley dam was built to an elevation of 603 m with a compacted earth fill embankment with internal drainage including a chimney drain and downstream blanket. The dam has undergone eight downstream raises, the first three using compacted earth fill and the remaining with compacted earth and cycloned underflow tailings. The final embankment raise to elevation of 626 m was reached in 2014. The maximum height of the dam is 43 m. The crest length is 695 m, with average downstream and upstream slopes of 1V:2.3H and 1V:1.4H, respectively. The downstream slope is vegetated. The total storage capacity is estimated at 14.9 Mm3 with the current volume of stored tailings and water estimated by Geoconsultoria at 12.2 Mm3 (drawing CM18-DE-011 Rev. 6 dated 31 August 2020). In addition to providing tailings storage, the Aroeira TSF also has the function of recirculating and clarifying water and receives pumped water from the underground mines.

 

The Aroeira TSF was built in the valley of a tributary of the Santa Catarina River, a tributary of the Paracatu River, which belongs to the São Francisco River basin. The Aroeira TSF's drainage basin area is approximately 330 ha, with no diversion ditching around the TSF. The Aroeira TSF is shown in plan and typical cross section in Figure 15-5.

 

The Aroeira TSF has been classified according to ANM Ordinance No. 70.389 of 05/17/2017. A dam classification “B” with a risk category of “Low” and potential associated damage of “High” has been assigned. The TSF has also been classified in terms of Failure Modes and Effect Analysis (FMEA) in accordance with the Normative Deliberation of the State Council for Environmental Policy (COPAM) No. 87, of 06/17/2005 as Class III – “High Potential for Environmental Damage”.

 

The tailings and embankment cover an area of approximately 100 ha. Tailings are deposited from the upstream embankment crest and perimeter of the Aroeira TSF. Deposition of tailings from the crest is to provide an upstream beach of at least 40 m wide adjacent to the embankment.

 

A shaft spillway was constructed in the initial phase for the life of the Aroeira TSF and consists of an inlet structure on the left shoulder of the dam which passes into a drop shaft and through a pipeline under the embankment (with energy dissipaters) and exits at the downstream toe of the embankment. The exit is into a reinforced, open concrete channel that passes into a rockfill lined section and then into the Santa Catarina River. The current inlet level of the decant tower is at elevation 621.5 m (Geoconsultoria drawing CM18-DE-011 Rev. 6 dated 31 August 2020).

 

Dam monitoring consists of instrument measurements and field inspections. Field inspections (regular routine inspection) are carried out fortnightly by Nexa personnel responsible for its operation, and every six months by an external consultant (Geoconsultoria). Piezometers and water level indicators are measured every two weeks, surface landmarks monthly, pluviometry, the graduated level of the reservoir and the flow meters are read daily. The data is reviewed by an external consultant (Geoconsultoria) on a monthly basis. Nexa utilizes an Integrated Dam Management System (referred to as SIGBar), which provides guidelines for document management, monitoring, evaluation, risk analysis, compliance with standards and legislation, training of personnel, operation of structures and other provisions.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000 

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The latest review by Geoconsultoria that was reviewed by SLR was dated 30 August 2019 (Relatório Técnico CM18-RT57 Rev.0). Geoconsultoria’s report states the dam safety condition is “Satisfactory” without the presence of erosions, cracks, or other features indicative of instability.

 

A risk assessment of the Aroeira TSF and associated infrastructure was completed in 2017 by Geoconsultoria (Relatório Técnico CM39-RT-01 Rev. 4). The method of analysis used was a variant of FMEA.

 

SLR relies on the conclusions of Geoconsultoria (Relatório Técnico CM18-RT57 Rev.0) and provides no conclusions or opinions regarding the stability of the listed dams and impoundments.

 

15.1.5 Tailings Storage in Pilha Garrote

 

The estimated active life of the Aroeira TSF was end of 2020/early 2021. In August 2019, Vazante implemented a new tailings disposal practice consisting of filtering and stacking tailings in the Pilha Garrote DSTSF constructed west of the Aroeira TSF. The tailings management consists of cyclones, vibratory screens, thickening, and filtering. Total tailings are pumped from the processing plant via pipeline to the cyclone station from where the underflow is transported by truck to the Pilha Garrote DSTSF, where it is dumped, spread, and compacted. Cyclone overflow is thickened and the underflow tailings from the thickener are pumped to the new filtration plant, located to the north east and adjacent to the Pilha Garrote DSTSF, from where the filter cake is transported by truck to the DSTSF. Water recovered at the filter plant and from the thickener overflow is piped to the Aroeira TSF.

 

The Pilha Garrote DSTSF has been designed with an average external slope of 1V:2.5H with 10 m high vertical lifts, intermediate slopes of 1V:2H and five metre wide benches. Surface runoff from the Pilha Garrote DSTSF is collected in a ditch at the toe of the facility and flows under gravity to the north-west side of the Aroeira TSF. The final height of the Pilha Garrote DSTSF will be 120 m and provide storage of approximately 8.6 Mm3. The Pilha Garrote DSTSF plan and typical cross section are presented in Figure 15-6.

 

Nexa plans on completing a progressive reclamation of the Pilha Garrote DSTSF as early as possible. Following the same practice implemented by Nexa for the Aroeira TSF, regular safety inspections of Pilha Garrote including geotechnical stability will be conducted by Geoconsultoría.

 

15.1.6 Former Tailings Storage Facilities

 

Other structures present at the Vazante Operation include the Antiga TSF and reservoir Modules I, II, and III. Of these structures, Module III is currently the only in operation. Module III is a geomembrane lined facility and serves as a sedimentation dam and reservoir for water supply when the Aroeira TSF undergoes maintenance.

 

The characterization of the structure of the Antiga TSF was revisited in 2016 and no longer considered a dam based on the definition of dam within the Brazilian legislation since the area is filled with mine waste material, it has been re-vegetated and there is no permanent water ponding. The revised characterization was approved by the State Environment Foundation (FEAM for its acronym in Portuguese), the regulatory body, in 2016.

 

 

 


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15.1.7 Waste Rock Storage Facilities

 

Several waste rock facilities are present at the Vazante Operation as a result of historical open pit mining activities. Currently, waste is only brought to surface for storage if backfilling is not possible. Waste is currently used to backfill the mined-out Morro da Usina and Sucuri open pits. The Bocaina pit is also designated for waste storage in the future, if required.

 

 

 

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Figure 15-5:       Aroeira Tailings Storage Facility Plan View and Dam Typical Cross-Section

 

 

 

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Figure 15-6: Pilha Garrote Dry Stack Tailings Storage Facility Plan View and Typical Cross Section

  

 

 

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16.0 Market Studies

 

16.1 Markets

 

16.1.1 Zinc Concentrate

 

Due to the ore mineralogy, zinc concentrate produced at the Vazante Operation is elevated in silica, calcium, magnesium, and carbonates resulting from the presence of carbonate gangue (predominantly dolomite). Nexa’s Três Marias zinc smelter in Brazil includes a processing circuit specifically configured to process the zinc silicate concentrate produced at the Vazante Operation and as a result, all of the concentrate produced at the Vazante Operation is processed at the Três Marias smelter where zinc metal is produced. The Vazante Operation concentrate accounts for approximately 70% of the feed to the Três Marias smelter. Deleterious elements affecting the Três Marias smelting operation are controlled at the Vazante Operation to ensure that they do not exceed the limits imposed by the smelter.

 

16.1.2 Lead Concentrate

 

The lead concentrate produced at the Vazante Operation is sold on the open market. Nexa provided information regarding sales contracts for lead concentrate produced at the Vazante Operation. According to this information, sales contracts are in place with concentrate traders for the sale of the lead concentrate and are considered to be consistent with industry norms. Since the lead concentrate produced at the Vazante Operation contains less than the preferred 45% lead, (typically the concentrate contains approximately 23% lead), the concentrate is subject to a small penalty charge, reported to be less than $1.00/t.

 

16.2 Contracts

 

Various operational support services are provided by contractors, including maintenance, consulting, concentrate haulage, environmental monitoring, information technology and communications, security, and janitorial services. There are currently 61 contractors providing services to the Vazante Operation.

 

 

 

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17.0 Environmental Studies, Permitting, and Plans, Negotiations, or Agreements with Local Individuals or Groups

 

The information presented in this section is based on documentation provided by Nexa for review. No site visit was conducted in support of the preparation of Section 17 of this Technical Report Summary.

 

17.1 Environmental Aspects

 

17.1.1 Mine Operation Overview

 

The Vazante Operation is located in the western portion of the state of Minas Gerais, Brazil, approximately 8.5 km east of the town of Vazante, 253 km southeast of Brasilia and 370 km northwest of Belo Horizonte. Open pit mining at the Vazante Operation commenced in 1969, while underground mining began in 1982. The Vazante Operation is in production with ongoing operations and development, with the projected mine life expected to continue to the end of 2040.

 

Open pit mining at the Vazante Operation was suspended in 2008 and currently the Vazante Operation is comprised of the following main facilities:

 

Two underground mines (Vazante and Extremo Norte).

 

•  An ore blending and reclaim facility.

 

•  Two processing plants (Plant W and Plant C) referred to as USICON W/C.

 

•  Aroeira TSF.

 

•  Pilha Garrote DSTSF and tailings filtering plant.

 

•  Waste rock storage facilities.

 

•  Water management facilities and infrastructure.

 

•  Ancillary buildings and infrastructure (administration, warehouse, storage, vehicle maintenance, laboratory, domestic waste management facilities, waste management, etc.)

 

Other structures present at the Vazante Operation include the Antiga TSF and Modules I, II, and III to the west of the concentrator plant site. These facilities are currently inactive, with the exception of Module III which is still in operation.

 

The Vazante Operation is the largest zinc operation in Brazil, processing approximately 1.5 Mtpa. Vazante Operation concentrates are sent to Nexa’s Três Marias zinc smelter complex, located approximately 250 km away. Processing on site is conducted in Plant W and Plant C, including crushing, grinding, and flotation. Concentrate is filtered for transport to the Três Marias smelter while combined Plant W and Plant C tailings are thickened and filtered prior to disposal in the DSTSF. Electricity supply is generated by hydroelectric power stations managed by Votorantim Energia.

 

Between 1969 and 2002 the Vazante Operation ore was processed in a former beneficiation plant and the tailings were deposited in the Antiga TSF. The area of the old tailings dam (Antiga TSF) is a containment basin formed by dikes up to 10 m high divided into modules, which received tailings from ore processing in the past. The area of the old modules and dam was developed south of the former beneficiation plant on the bed of the Barroquinha stream, which was diverted. The former beneficiation plant operations were interrupted due to ground geotechnical instability triggered by the formation of sinkholes resulting from the local geology and lowering of the phreatic level. The former beneficiation plant was decommissioned in 2005.

 

 


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The Pilha Garrote DSTSF currently receives the tailings stream generated at the new beneficiation plant (USICON W/C) whereas the Aroeira TSF provides clarification of the water pumped from the underground mines. Module III remains active to receive water from the underground mines during the maintenance of the pumping system of the Aroeira TSF.

 

There is no accommodation complex at the Vazante Operation. Mine personnel commute from the municipality of Vazante to the operations.

 

17.1.2 Environmental Baseline

 

The environmental baseline summary presented in this section was taken from Amec (2017).

 

17.1.2.1 Climate

 

The region is classified as warm (calid) sub-humid with four to five dry months annually. Average temperatures vary between 13°C and 27°C in the winter and between 18°C and 30°C in the summer.

 

The historical average annual rainfall is 1,441.5 mm, with more than 80% occurring during the rainy season, which runs from October to March. The predominant wind directions are northeast to southwest.

 

17.1.2.2 Air Quality and Noise Levels

 

Air quality monitoring between January 2014 and August 2016 included measurements of total suspended particles (TSPs), inhalable particles, sulphur dioxide (SO2) and nitrogen oxide (NO2) at five sampling points. Results included:

 

•  Concentrations of TSPs and inhalable particles were below the maximum permitted values established by the Ministry of Environment (CONAMA) for all monitoring points during the 2015 sampling program. For 2014, exceedances were registered for both parameters during the dry season in the monitoring station near the roads. No evidence of mitigating measures was noted to be in place. For the Extremo Norte monitoring point one value (July 2014) was found to be above the limit. CONAMA Resolution No. 03/1990 allows one exceedance for each parameter for each year, therefore the readings were not considered to be out of compliance.

 

•  Concentrations of SO2 were below the maximum permitted values for 2014 and 2015 in all monitoring stations, except one value.

 

•  Results of NO2 were below the maximum permitted values.

 

17.1.2.3 Water Quality

 

Water sampling points were established in the Santa Catarina River to assess water quality and contamination. In addition, the Instituto Minero de Gestão das Aguas 16-1 (IGAM) monitored water quality in the State of Minas Gerais using two monitoring stations in the Santa Catarina River, over a 34 quarter period, running from March 2008 to June 2016. According to the monitoring results in 2014 and 2015, parameters in the Santa Catarina River that exceeded the maximum limit values (COPAM/CERH-MG No. 01/2008) were suspended solids, turbidity, cadmium, and lead.

 

 

 

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The Environmental Impact Assessment (EIA) for the USICON W/C indicates acceptable dissolved oxygen levels in the Santa Catarina River. In addition, total solids and turbidity were below the maximum limit, and had a very low concentration compared to the maximum limit established by COPAM 010/86. Cadmium and lead were found to be below the laboratory analytical detection limits.

 

The IGAM results also identified bacteriological contamination of water at both sampling points, consisting of thermotolerant coliforms, and E. coli.

 

17.1.2.4 Hydrology

 

The Vazante Operation is located on the Santa Catarina River sub-basin, which is a tributary of the Paracatu River in the São Francisco River basin. The Santa Catarina River has a drainage area of 1,182 km². Its main tributaries are the Carrapato creek, and Carranca, Indaiazinho, and Arrependido streams. The Santa Catarina River has a dendritic drainage pattern. Near the municipality of Vazante, the Santa Catarina River runs through carbonate lithologies and a flattened topography.

 

17.1.2.5 Groundwater

 

Groundwater monitoring at the Vazante Operation commenced in 1989, based on a piezometer network. The numbers of piezometers in the network has steadily increased, from an initial 28 to over 155 currently. Pumping by the Vazante Operation has lowered water levels in some of the aquifers.

 

17.1.2.6 Biological Considerations

 

From the primary data obtained for the EIA for the expansion and modification of the concentrator plant, the following protected species according to the International Union for Conservation of Nature (IUCN) and Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) lists were identified within the influence area of the Vazante Operation:

 

•  Three bird species (2015 to 2016) within the direct influence area were classified as near threatened according to IUCN.

 

•  Five mammal species (2015 to 2016) within the direct and indirect influence area were listed in Appendix I and II of CITES.

 

A threatened species management plan, developed by Ecolab in 2016, is currently in place for the Vazante Operation.

 

17.1.2.7 Social and Heritage Considerations

 

The 2010 census documented approximately 211,560 persons living in the micro-region of Paracatu. The municipality of Vazante is the third largest in the region, with a population of approximately 20,600, or approximately 9% of the micro-region. Population emigration into the area is approximately 4% to the municipality, and approximately 5% overall to the micro-region of Paracatu.

 

The municipality of Vazante has public, state, and private schooling available, and a small private tertiary institution. The illiteracy rate for those above 18 is lower than the average for the state of Minas Gerais as a whole.

 

 

 

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17.1.3 Environmental Studies and Key Environmental Issues

 

Two types of environmental documents must be presented to the national authorities in the first stage of the licensing process (Licença Prévia). The EIA is a set of technical reports destined to instruct the licensing process, while the report on environmental impacts, Relatório de Impacto Ambiental (RIMA), is the document which reproduces EIA conclusions, in an accessible and easy language. The RIMA's purpose is to inform the public. EIAs and RIMAs are normally accompanied by a third document, the Environmental Control Plan, Plano de Controle Ambiental (PCA).

 

The following environmental studies have been prepared for the Vazante Operation:

 

•  EIA/RIMA for the new beneficiation plant for the Vazante Mine, 2000

 

•  EIA/RIMA/PCA for the Vazante underground mine (Villemita), 2001

 

•  EIA/RIMA for Extremo Norte, 2009

 

•  PCA for Extremo Norte, 2011

 

•  PCA for the concentrator plant (USICON W/C), 2011

 

•  EIA/RIMA/PCA for the Lead Project, 2011

 

•  EIA/RIMA/PCA for the Pilha Garrote DSTSF Project, 2016

 

•  EIA/RIMA/PCA for the expansion and modification of the concentrator plant (USICON W/C), 2017

 

•  Study of alternatives for future use of the mining unit following its decommissioning, 2017

 

•  Review of the Pilha Garrote DSTSF Project, 2017

 

•  Environmental Control Report and PCA for the expansion and modification of the concentrator plant (USICON W/C), 2018

 

The EIAs present the identification of potential environmental effects resulting from project activities for the construction, operation, and closure stages. The mitigation measures are mostly addressed through a number of environmental control programs presented in the EIAs rather than identifying specific mitigation activities.

 

The Vazante Operation environmental management programs have been developed based on the potential environmental effects identified through the various EIAs conducted for the Vazante and Extremo Norte mine operations, listed above. The environmental management programs presented in the EIAs and PCAs for the Vazante Mine (EcoLab, 2018) are as follows:

 

•  Environmental management and control of the operation works.

 

•  Risk management and emergency response.

 

•  Cleaning and maintenance of vehicles and equipment.

 

•  Mine closure environmental plan.

 

•  Solid waste management.

 

•  Water resources.

 

•  Liquid effluents control.

 

•  Atmospheric emission control.

 

•  Vegetation removal control.

 

•  Recovery of degraded areas.

 

•  Social communication and social-environmental information.

 

 

 

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•  Environmental training and education.

 

The environmental management programs presented in the EIAs and PCAs for the Extremo Norte Mine (BRANDT, 2011) are as follows:

 

•  Control of erosive processes.

 

•  Management and control of rainfall water and liquid effluents.

 

•  Monitoring of liquid effluents.

 

•  Monitoring of surface water quality and groundwater quality.

 

•  Hydrological and hydrogeological monitoring.

 

•  Management and control of solid waste.

 

•  Atmospheric emissions control.

 

•  Equipment maintenance.

 

•  Monitoring of air quality and ambient noise.

 

•  Monitoring and control of environmental legacy components.

 

•  Monitoring and salvage/relocation of fauna.

 

•  Protection and monitoring of underground cavities.

 

•  Restoration actions.

 

•  Waste rock environmental control.

 

•  Contingency plan.

 

•  Conceptual mine closure.

 

•  Rehabilitation of degraded areas.

 

•  Social communication.

 

•  Research, rescue, and valuation of historical and archaeological remains.

 

•  Environmental education.

 

•  Training of labour workers and prioritization program.

 

In the SLR QP’s opinion, the environmental management programs for the Vazante Operations are adequate to address potential issues related to environmental compliance.

 

The following 2020 annual environmental reports were provided for SLR’s review:

 

•  Report for the Extremo Norte Mine operation addressing Condition 1 from Operation Licence No. 005/2016, related to administrative process COPAM No. 104/1988/056/2014 (Nexa, 2020a)

 

•  Report for the Vazante Mine operation addressing Condition 1 from Operation Licence No. 051/2019, related to administrative process COPAM No. 104/1988/063/2018 (Nexa, 2020b)

 

According to information provided by Nexa to SLR, monitoring of fauna was expected to be carried out only during the Installation Licence phases of the Vazante Operation (currently all active licenses correspond to the Operating License phase). Although it is not a requirement in the Operation Licences, SLR recommends considering the implementation of a monitoring program for flora and fauna for the Vazante Operation. SLR notes that the environmental management programs for the biological environment address fauna but not flora.

 

 

 

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17.1.3.1 2020 Monitoring Report for the Extremo Norte Mine Operation

 

The Nexa (2020a) report documents the monitoring program completed in 2019, which was comprised of four components:

 

· Liquid effluents

 

· Solid waste residues and oily effluents

 

· Atmospheric emissions (air quality)

 

· Noise

 

The water monitoring results were compared against Norm COPAM-CERH 01/08. According to the annual monitoring report (Nexa, 2020a), the parameters evaluated in 2019 for pit dewatering and domestic wastewater were in compliance with the permissive limits established by the legislation. The laboratory employed to conduct water quality analyses at the Vazante Operation is accredited by the National Institute of Metrology (Inmetro for the acronym in Portuguese). Water quality monitoring results and laboratory certificates have been documented in the annual monitoring report.

 

Nexa (2020a) states that disposal of solid and oily waste residues at the Extremo Norte Mine is conducted in compliance with the applicable norms and legislation at a national and state level, with appropriate controls for segregation, collection, and transport of residues. A table documenting details of the disposal such as type of residue, source, transportation company, and final disposal destination is included in the annual monitoring report. Burning of residues, disposal in non-licenced landfills or incinerators, and disposal in natural water bodies is forbidden.

 

Results of the air quality monitoring program were compared against maximum permissible limits presented in CONAMA No. 03/1990 and CONAMA No. 491/2018 resolutions. According to the annual monitoring report (Nexa, 2020a), the parameters evaluated in 2019 (TSP, PM10, SO2 and NO2) at four monitoring locations were in compliance with the legislation. The air quality monitoring reports prepared by Limnos, an external laboratory retained by Nexa, are appended to the annual monitoring report. Data measuring reports from Medicoes Ambientais Consultoria, a consulting firm retained by Nexa, are also appended to the annual monitoring report.

 

Results of the ambient noise monitoring program were compared against maximum permissible limits presented in CONAMA No. 03/90, which is the most stringent norm on ambient noise and assures compliance with CONAMA No. 10.100/90. According to the annual monitoring report (Nexa, 2020a), the monitoring results for the two campaigns conducted in 2019 at six monitoring locations were in compliance with the legislation for five locations. In one location the maximum permissible limits were slightly exceeded due to noise sources (i.e. local fauna) not related to the mining activity. The noise monitoring reports prepared by Limnos are appended to the annual monitoring report.

 

17.1.3.2 2019 to 2020 Environmental Programs at the Vazante Mine Operation

 

The objective of the Nexa (2020b) report is to provide information about the implementation of activities in 2019 and 2020 in agreement with the following environmental control plans specifically related to the Pilha Garrote DSTSF Project:

 

· Risk management and emergency response

 

· Cleaning and maintenance of vehicles and equipment

 

· Mine closure environmental plan

 

 

 

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· Solid waste management

 

· Water resources

 

· Liquid effluents control

 

· Atmospheric emission control

 

· Control of erosive processes

 

· Recovery of degraded areas

 

· Social communication and social-environmental information

 

· Environmental training and education

 

· Air quality monitoring

 

· Geotechnical monitoring

 

Nexa states in the (Nexa, 2020b) report that the applicable environmental programs and plans have been carried out satisfactorily in compliance with conditions from Operation Licence No. 051/2019.

 

Water quality monitoring reports are prepared quarterly to document the monitoring results for effluents and the receiving water bodies. These quarterly reports are submitted to the Regional Environment Superintendence (SUPRAM-NOR) in compliance with Condition 01 of Operation Licence No. 10/2012 (COPAM No. 104/1988/049/2011). The results of the analyses for all the evaluated parameters are presented and compared against the maximum permissible limits established by the current legislation. Contextualization and rationale for deviations that occurred during the reported period are provided in the (Nexa, 2020b) report. The report from the fourth quarter of 2019 was provided to SLR as an example. Based on the documentation available for review, the SLR QP is not aware of any compliance issues raised by the authorities associated with the Vazante Mine water quality monitoring program.

 

Regarding the domestic wastewater effluents, the 2019 monitoring results displayed exceedances for biological oxygen demand (BDO), chemical oxygen demand (COD), phenols, and suspended solids. Nexa attributed the exceedances to the initial period for stabilization of the new biological treatment system, which relies on anaerobic bacteria for degradation of organic matter. A significant improvement was observed by the fifth month of operation (November 2019) of the treatment system with only two exceedances of BDO in January 2020 and April 2020.

 

Results of the Vazante Mine air quality monitoring program were compared against maximum permissible limits presented in CONAMA No. 03/1990 and CONAMA No. 491/2018 resolutions. According to the annual monitoring report (Nexa, 2020b), the parameters evaluated in 2019 (TSP, PM10, SO2 and NO2) at four monitoring locations were in compliance with the legislation except, for one exceedance of PM10 at one monitoring location.

 

SLR understands that the requirement for submission of quarterly reports (water quality and gas monitoring) was suspended temporarily in the state of Minas Gerais on March 20, 2020 through Decree 47.890 due to the public health emergency situation triggered by the COVID-19 pandemic.

 

SLR did not identify any environmental issues from the documentation available for review that could materially impact the ability to extract the mineral resources and mineral reserves at the Vazante Operation.

 

 

 

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17.1.4 Environmental Management System

 

Nexa utilizes SIGBar for the TSFs, which provides guidelines for document management, monitoring, evaluation, risk analysis, compliance with standards and legislation, training of personnel, operation of structures and other provisions.

 

The environmental programs defined in the PCAs are an integral part of the Environmental Management System for adoption of measures aimed at the prevention, mitigation, and control of potential environmental impacts resulting from mining activities.

 

According to Nexa’s website and 2019 Annual Report, Nexa identifies and manages the main risks from both an operational and strategic point of view, reducing and mitigating impacts to maintain business sustainability. Nexa has an integrated management system that establishes the guidelines that govern the conduct of the business, with a focus on quality management of environmental, health and workplace safety, and social responsibility issues. In addition, Nexa follows applicable environmental laws and regulations pertaining to its business in each country where it operates (Nexa, 2019).

 

Nexa has stated the following environmental goals in its 2020 Annual Report:

 

· 75% recirculation and lower specific use of water.

 

· Reduce the specific emission of greenhouse gases by 5%.

 

· Decrease the disposal of tailings in dams and a 50% reduction in the specific generation of mining and smelting waste.

 

· Ensure that 100% of the units have a pre-prepared future use alternative studies and updated decommissioning plans, in line with the sector’s benchmark standards.

 

17.2 Mine Waste and Water Management

 

17.2.1 Environmental Geochemistry

 

There is no specific geochemical testing protocol or guideline within the Brazilian regulations for geochemical characterization of mine waste. The only existing standard related to testing for classification of solid waste is norm ABNT-NBR 10.004. The classification standard from this norm is usually used to classify solid waste from sanitary landfills based on the results of leaching the material to be classified with acetic acid, and also based on the results of sample solubilization with distilled water.

 

Tailings characterization, including laboratory testing, was carried out by Hidrogeo Assessoria Ambiental Ltda (Hidrogeo) (2016) and was conducted in accordance with the Brazilian norm ABNT-NBR 10.004. The Hidrogeo concluded that the tailings should be classified as Class II-A, non-hazardous and inert, in accordance with the norm.

 

According to Nexa no indication of acid generation nor metal leaching has been identified through water quality monitoring conducted for several years of operation. SLR recommends that Nexa consider conducting additional geochemistry testing and characterization ahead of mine closure following international guidelines and common practices to investigate the potential for developing acid rock drainage (ARD) and/or metal leaching in the long term. The characterization should be used to confirm the closure strategy and closure water management plan requirements to assure compliance with applicable water quality standards during post-closure.

 

 

 

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17.2.2 Tailings Management

 

Tailings are currently disposed as filtered tailings at the Pilha Garrote DSTSF. The Aroeira TSF is currently used as a water storage facility and for tailings disposal when the infrastructure of the Pilha Garrote is temporarily down for maintenance. Waste rock is used for backfilling or disposed of at surface in mined-out open pits. Descriptions of the Aroeira TSF and Pilha Garrote DSTSF are provided in Section 15 of this Technical Report Summary.

 

According to the tailings characterization conducted by Hidrogeo and discussed above, there is no potential for leaching of metals or release of sulphates from the tailings. Based on this premise, there is no plan to reduce water infiltration through the tailings at closure. The preferred option for closure of the Aroeira TSF is to construct a saddle/spillway in the natural terrain near the right dam abutment and to profile the surface of the tailings in order to eliminate the accumulation of water on the surface.

 

Regular dam safety inspections have visually confirmed that the tailings beach of the Aroeira TSF between the dam and the tailings pond is greater than 40 m. The Aroeira TSF has been classified in accordance with ANM as classification “B” with a risk category of “Low” and potential associated damage of “High”. The Aroeira TSF has also been classified in terms of FMEA as Class III – “High Potential for Environmental Damage”.

 

Dam monitoring of the Aroeira TSF consists of instrument measurements and field inspections. Dam monitoring data is reviewed by an external consultant (Geoconsultoria) on a monthly basis. Fortnightly inspections are completed by Nexa personnel and Geoconsultoria who inspect the Aroeira TSF twice annually. Nexa utilizes SIGBar which provides guidelines for document management, monitoring, evaluation, risk analysis, compliance with standards and legislation, training of personnel, operation of structures and other provisions.

 

The latest review by Geoconsultoria that was reviewed by SLR was dated 30 August 2019 (Relatório Técnico CM18-RT57 Rev.0). Geoconsultoria’s report states the dam safety condition is “Satisfactory” without the presence of erosions, cracks, or other features indicative of instability.

 

17.2.2.1 Recommendations:

 

· The Golder closure report (No.: RT-006_169-525-2593_03-J 75, dated January 2018) recommends that a more detailed assessment be made of the impact of ore processing on the potential for release of sulphates from the tailings at the Pilha Garrote DSTSF.

 

· The placement and compaction of the filtered and cyclone tailings during the wet season must be considered.

 

· Dust generation from the Pilha Garrote DSTSF during the dry season must be considered.

 

· The water balance for the Aroeira TSF must be reviewed to determine the impact of use as a water management facility, increased mine dewatering, and surface runoff from the Pilha Garrote DSTSF.

 

17.2.3 Water Management

 

Limited information on water management details was provided in the documentation reviewed by SLR, in particular regarding design details. The description of the site water management system presented in this subsection is taken from Golder (2018).

 

 

 

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Industrial effluents from the Vazante Operation are directed to the Aroeira TSF together with surface runoff from the crushing area, chemical laboratory area, and channel network for surface water collection. Underground mine dewatering is pumped to surface and conveyed via gravity to the Aroeira TSF tailings pond through a concrete channel. Excess water collected in the tailings pond is released to the Santa Catarina River through the shaft spillway located near the Aroeira TSF left abutment.

 

The latest hydrological and hydraulic study, carried out in May 2017 and presented in Geoconsultoria’s No. CM64-RT03 report, verified the adequacy of the spillway capacity for floods with a return period of 10,000 years, while maintaining a freeboard of 1.29 m. The regular dam safety inspections include the spillway in order to verify its unobstructed operation.

 

A monthly monitoring program is in place, checking water quality from a sampling point at the Aroeira TSF spillway outlet into the Santa Catarina River. Samples collected are analyzed for physical, chemical, and biological parameters by an independent third-party laboratory. The Aroeira TSF is the primary water storage facility on-site and is used for recirculation of water for ore processing, and for water clarification to remove suspended solids through gravity settling, providing a clarified liquid effluent.

 

Tailings are currently disposed as filtered tailings in the Pilha Garrote DSTSF constructed west of the Aroeira TSF. The Pilha Garrote DSTSF includes an underdrain system to ensure that infiltration is adequately captured for stability purposes. The Aroeira TSF remains in operation for the collection of underground mine dewatering and as the water supply storage dam for the processing plant.

 

Domestic wastewater from administrative areas, including the dressing rooms and bathrooms, is treated in the sanitary effluent treatment plant located in the administration area. A second sanitary effluent treatment plant is located between the crushed ore yard and the Aroeira TSF for treatment of domestic wastewater from the USICON W/C concentrator plant area.

 

Dewatering from the Extremo Norte Mine is pumped to the sump located at the bottom of the inactive Pit 5A. After undergoing a decantation process by gravity, the water is pumped into a channel for discharge to the Ouro Podre Stream.

 

According to Golder (2018), Nexa is planning to connect the galleries of the Extremo Norte Mine and main Vazante Mine in 2025 so all mine dewatering will be directed to the main pumping station (EB N-297) installed at the 297 m level of the Vazante Mine.

 

According to Golder (2018), diversion channels that direct freshwater to natural watercourses have been implemented to reduce the volume of water to be managed at the various mine facilities.

 

No information on site wide water balance modelling or an accompanying flow logic diagram was found in the documents reviewed. Updating the water balance modelling is of particular relevance when considering the MDP that is underway with the water pumping capacity increase at the bottom of the mine from 10,000 m3/h to 15,000 m³/h to be completed in 2022. The implementation of the MDP would increase the underground mine dewatering rate discharged to the Aroeira TSF pond. Conversely, water from the tailings stream is no longer collected in the Aroeira TSF pond since tailings disposal ceased at this facility. If there is a net reduction of water volume collected in the Aroeira TSF pond relative to the current operation, the availability of sufficient make-up water for ore processing under various climatic conditions will have to be confirmed through water balance modelling. If there is a net increase of water volume collected in the Aroeira TSF pond, the incremental effluent discharge to the Santa Catarina River will have to be determined through water balance modelling. The change in effluent discharge rate could influence water quality in the Santa Catarina River.

 

 

 

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As noted in Section 17.2.2 Tailings Management of this Technical Report Summary, SLR recommends conducting additional water balance modelling of the Aroeira TSF to determine the impact of use as a water management facility, increased mine dewatering, and surface runoff from the Pilha Garrote DSTSF. Different climate scenarios should be simulated to account for years with annual precipitation below and above the statistical average (i.e. dry and wet years).

 

Nexa has developed a data management system for the Vazante Operation to document data associated with the water balance and the water management system. The water inventory at the site, water use for operations, and environmental water monitoring are tracked on a monthly basis and compared on an annual basis against previous years in order to identify trends and track improvements.

 

17.2.3.1 Surface Water Quality Monitoring

 

The main effluent generated from the Vazante Operation in terms of flow and potential environmental impact is the water pumped from the underground mines. Mine dewatering is conveyed to the Aroeira TSF, the Extremo Norte Mine sump (located at the bottom of Pit 5A) and Module III, when the Aroeira TSF is temporarily inactive for maintenance. From these three collection points clarified water is released to the Santa Catarina River and the Ouro Pobre Stream, downstream of the Vazante and Extremo Norte mines, respectively.

 

The Vazante Operation has a systematic monitoring network for surface water quality in streams within the area of influence, and effluents generated during the operations. Monitoring frequencies are daily or monthly depending on the location. Report submission to the authorities takes place quarterly. The monitoring network includes the following 26 flow measuring locations (Golder, 2018):

 

· Seven stations in the Santa Catarina River.

 

· Two stations in the Barroquinha Stream.

 

· One station in the Indaiá Stream.

 

· Two stations in the Ouro Podre Stream.

 

· One location for treated effluent at the Módulo III overflow structure.

 

· One location for untreated effluent from the underground mines before discharging to the Aroeira TSF.

 

· One location for untreated effluent from the Aroeira TSF underdrain system.

 

· One location for treated effluent at at the Aroeira TSF spillway outlet.

 

· Four locations for effluents associated with wastewater treatment from vehicle washing and maintenance.

 

· Five locations for effluents associated with domestic wastewater treatment.

 

· One location for effluent from the Extremo Norte Mine sump.

 

17.2.3.2 Groundwater Quality Monitoring

 

Based on information presented in Golder (2018), monitoring of groundwater from wells appears to take place at 20 locations. Eight of these locations correspond to the Extremo Norte Mine.

 

The monthly monitoring of groundwater is carried out in compliance with Condition 01 of Operation Licence No. 10/2012 and reports are required to be submitted every six months. Toxicity parameters are also monitored at four stations and submitted annually (Amec, 2017).

 

 

 

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SLR was not provided groundwater quality reports for review, and therefore, SLR has not corroborated if reports documenting groundwater monitoring results were prepared and submitted to SUPRAM-NOR in 2019 or 2020.

 

17.3 Project Permitting

 

17.3.1 Current Permits, Approvals and Authorizations

 

The main activity of the Vazante Operation is defined as “open pit or underground mining in karstic areas with or without treatment” involving tailings disposal, waste rock disposal, and infrastructure works (Golder, 2018). The current operating licences, as provided by Nexa in October 2020, are listed in Table 17-1

 

Table 17-1:       Operating Licences

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Process
PA/COPAM/No.
  Certificate
No.
  Licensing
Objective
  Issue Date
(DD/MM/YYYY)
  Expiration Date
(DD/MM/YYYY)
  Status
  104 /1988/033/2006   Operation Licence
264/2012-2017
  Mining and processing of zinc ore   17/9/2007   17/9/2012   Inactive (superseded by Operation Licence 028/2013-2019)
  104 /1988/049/2011   Operation Licence
010/2012-2017
  Open pits, process plant, tailings dam, waste dump, roads for mineral and waste transport, drainage channels, energy substations and gas station   19/4/212   19/4/2017   Under renewal through COPAM No. 104/1988/059/2016
  104 /1988/052/2012   Operation Licence
015/2012-2017
  Lead and silver recovery project   26/6/2012   26/6/2017   Under renewal through COPAM No. 104/1988/059/2016
  104 /1988/053/2012   Operation Licence
028/2013-2019
  Underground mining and emulsion tank   18/7/2013   18/7/2019   Under renewal through COPAM No. 104/1988/059/2016
  104 /1988/056/2014   Operation Licence
005/2016-2020
  Extremo Norte Project   31/3/2016   31/3/2020   Under renewal through COPAM No. 104/1988/059/2016
  104 /1988/064/2018   Operation Licence
038/2019-2029
  Reprocessing of deposited tailings   23/4/2019   12/4/2029   Active
  104/1988/063/2018   Operation Licence
051/2019-2029
  Tailings stack and mineral treatment unit (dry stack)   31/5/2019   27/4/2029   Active

 

 

 

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Licences associated with water management and water use are listed in Table 17-2. Renewal applications have been lodged, where applicable, for the water licences in use.

 

Table 17-2:     Licences for Water Management and Water Use

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Agency     Purpose   File Number     Issue Date
(DD/MM/YYYY)
  Expiration Date
(DD/MM/YYYY)
  Status
SUPRAM-NOR     Construction of a dam on Santa Catarina tributary. Waste disposal and recovery of water for industrial use   01805/2008-2013     6/10/2008   6/10/2013   Active under renewal application No. 0910318/2013 filed on 5/24/2013 (Case 10107/2013)
IGAM     Barrel Stream remediation   02986/2009-2014     18/11/2009   18/11/2014   Active under renewal application
17988/2014
SUPRAM-NOR     Underground pumping for Extremo Norte Mine   01887/2011-2016     29/6/2011   29/6/2016   Active under renewal application No. 21392/2016 (22/67/2016)
SUPRAM-NOR     Palmito stream diversion   00218/2013-2016     4/2/2013   26/6/2016   Inactive (superseded by 2467/2018-2023)
SUPRAM-NOR     Underground pumping for Vazante Mine   1672/2013-2019     31/7/2013   18/7/2019   Renewal in progress by Process No. 43659/2019 (16/7/2019)
SUPRAM-NOR     Santa Catarina River water catchment   201/2014-2016     11/2/2014   26/6/2016   Inactive (superseded by 2282/2016)
  SEMAD     Santa Catarina River water catchment     2282 /2016   17/11/2016   31/3/2020   Inactive (superseded by 1707136/2020)
  SUPRAM-NOR     Diversion of the Palmito stream to build the Aroeira TSF     2467/2018-2023     16/5/2019   8/6/2023   Active
  SUPRAM-NOR     Water intake from Santa Catarina River for industrial purposes     1707136 /2020   15/9/2020   15/9/2030   Active

 

 

 

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Certificate No. 1370.01.0021690/2020-38 for absence of acid drainage was issued in 2020, valid for one year (to be renewed annually). Certificate No. 1370.01.0021690/2020-38 on annual report on storm water drainage system was issued in 2020, valid for one year (to be renewed annually). Certificate No. R0079622/2018 stipulating no evidence of leakage or contamination in the dam area was issued in 2018, valid for two years (to be renewed every two years).

 

17.3.2 Environmental Licensing and Approval

 

The description in this section was taken from Amec (2017). Mining activities are subject to mandatory environmental licensing by the Federal or State Environmental Agency, depending on the potential environmental impact. Environmental licenses are granted prior to mine construction, installation, expansion, or operation.

 

Generally, the environmental licensing is a three-stage process:

 

· A Preliminary License (LP) must be obtained during the planning stage evaluation. An EIA and a closure and remediation plan must be prepared during the LP stage. Public hearings are usually called to present the EIA to the communities and authorities. The LP usually imposes conditions that must be complied with by the mining company. The environmental authority will also set the amount of the environmental compensation, which is a minimum of 0.5% of the projected development investment.

 

· An Installation Licence (LI) is required prior to construction. The holder must present a PCA for approval. Once the PCA is approved, an LI is granted and usually has conditions attached specific to the operation. A mining concession can only be granted by the Minister of Mines once the holder has obtained an LI.

 

· An Operations Licence (LO) is granted once construction is complete and inspection by the environmental authorities confirms that the conditions imposed in the LI and commitments made in the PCA have been kept.

 

Although the Brazilian legal system provides for two types of titles, one for exploration and one for mining, it does grant security that the holder of an exploration licence can mine any deposit that is discovered within the granted title. The government is required to grant a mining concession to an entity that has explored for, identified a Mineral Resource, obtained ANM approval of the exploration report, filed applications for a mining concession in a timely manner, and obtained an LI.

 

Reasons for not granting a mining concession would be on the grounds of public interest, or if the Federal Government considers that it could have a negative effect on certain interests which are more important than mineral exploitation. In the latter instance, in those cases where a final exploration report has already been approved, a mining concession applicant is entitled to be indemnified by the Federal Government for any expenses incurred relating to the completed exploration work.

 

Brazil has a concept that is termed “environmental conservation units”, which can be created by either the Federal Government, States, or Municipalities, and can be either total protection conservation units, where industrial activities such as mining cannot take place, or sustainable use conservation units, where some industrial activities (including mining) may be carried out as long as they comply with regulatory requirements. Every environmental conservation unit in Brazil must have its own management plan that sets out the regulations for the administration and occupation of the unit. The plan includes regulations applicable to the zone that surrounds the unit.

 

 

 

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17.4 Social or Community Requirements

  

17.4.1 General Context

 

The closest community to the Vazante Operation is the municipality of Vazante, located approximately 8.5 km east, with a population of approximately 20,600 residents. The closest major urban centre is Brasilia, approximately five hours away via roadways (250 km), with a population of approximately 4.7 million residents. This section presents the results of the social review based on a review of Nexa’s policies, programs, social risk management systems, and/or social performance against relevant International Finance Corporation (IFC) Performance Standards (PSs). While the IFC PSs have been used as a framework this social review does not represent a detailed audit of Nexa’s compliance with IFC PSs or specific guidelines. Nexa’s social performance is benchmarked against the following 2012 IFC PSs:

 

· PS1: Social and Environmental Assessment and Management Systems requires that companies identify, assess, and mitigate the social and environmental impacts and risks they generate throughout the lifecycle of their projects and operations. From a social perspective, the requirement includes: a comprehensive social assessment; identification of critical social impacts and risks; community consultation and engagement; information disclosure; mitigation plans to address impacts and risks; and development of an organizational structure with qualified staff and budgets to manage the overall social management system.

 

· PS2: Labour and Working Conditions incorporates the International Labour Organization conventions that seek to protect basic worker rights and promote effective worker/management relations.

 

· PS4: Community Health and Safety declares the project’s duty to avoid or minimize risks and impacts to community health and safety and addresses priorities and measures to avoid and mitigate project related impacts and risks that might generate community exposure to risks of accidents and diseases.

 

· PS5: Land Acquisition and Involuntary Resettlement considers the need for land acquisition or involuntary resettlement of any individual, family or group; including the potential for economic displacement.

 

· PS7: Indigenous Peoples considers the presence of Indigenous groups, communities, or lands in the area that may be directly or indirectly affected by projects or operations.

 

· PS8: Cultural Heritage. This standard is based on the Convention on the Protection of the World Cultural and Natural Heritage. The objectives are to preserve and protect irreplaceable cultural heritage during a project's operations, whether or not it is legally protected or previously disturbed and promote the equitable sharing of benefits from the use of cultural heritage in business activities.

 

SLR notes that PS3 Resource Efficiency and Pollution Prevention and PS6 Biodiversity Conservation correspond to environmental performance standards, which have been discussed at the beginning of Section 17 of this Technical Report Summary.

 

17.4.2 Social and Environmental Assessment and Management Systems

 

At a corporate level, Nexa has adopted the guidelines of the International Integrated Reporting Council (IIRC) and the standards for the Global Reporting Index (GRI). The IIRC guidelines promote a cohesive and integrated approach to reporting on organizational activities. The GRI standards provide best practices for public reporting on economic, environmental, and social impacts in order to aid Nexa and its shareholders and stakeholders understand their corporate contribution to sustainable development. These standards were reported on in the most recent Nexa Annual Report (Nexa, 2020c). With respect to social issues, the 2019 Annual Report provided details of corporate activities aligning with the following GRI Standards:

 

 

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· Employment

 

· Occupational health and safety (OHS)

 

· Non-discrimination

 

· Training and education

 

· Diversity and equal opportunities

 

· Freedom of association and collective bargaining

 

· Child labour

 

· Forced or compulsory labour

 

· Human rights assessment

 

· Local communities

 

· Social assessment of suppliers

 

· Socio-economic compliance

 

Nexa’s 2019 Annual Report also includes reporting on corporate progress towards several sustainable development goals. With respect to social environment issues, these include:

 

· Gender equality

 

· Decent work and economic growth

 

· Good health and well-being

 

· Peace, justice, and strong institutions

 

· Quality education

 

· Reduced inequalities

 

· Sustainable cities and communities

 

· Responsible consumption and production

 

· Life below water

 

Nexa has a corporate compliance policy (PC-RCC-CCI-005-EN) meant to guide Nexa representatives and third parties. The compliance policy includes the following policies and procedures:

 

· Code of Conduct

 

· Anti-Corruption Policy

 

· Money Laundering and Financing Terrorism Prevention Policy

 

· Antitrust/Competition Policy

 

· Insider Trading Policy

 

· Disclosure Policy

 

· Compliance Program Manual

 

· Money Laundering and Financing Terrorism Prevention Manual

 

 

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· Gifts and Hospitality Procedure

 

· Relationships with Government Representatives Procedure

 

· Travel and Entertainment Procedure

 

· Integrity Due Diligence Procedure

 

· Conflict of Interests Procedure

 

With respect to the Vazante Operation, Nexa has developed and utilizes a number of social management programs and tools to help the company work with the nearby communities. These include:

 

· Risk analysis matrices

 

· Stakeholder tracking

 

· Social Characterization Plan

 

· Vazante Community Relations Plan (Local Development Plan)

 

In order to better understand the specific issues of the community and address the concerns that arise at the Vazante Operation, Nexa implements a Complaints and Requests Register guided by the Request, Consultation, Claims and Complaints Procedure. It details roles, responsibilities, and commitments to collect and respond to the public in a fair and equitable manner. All communications and complaints are recorded, investigated, evaluated, and resolved in accordance with the Procedure. The process aims to provide Nexa with a better understanding of the local population and related issues. Nexa also maintains a matrix of stakeholders, which is a database with relevant information, such as personal data, a record of interactions, and stakeholder roles and influence in the community. At the time of writing, most complaints and requests in 2020 had already been resolved, with few high-priority complaints about site operations.

 

Nexa maintains a Risk Register for the Vazante Operation called the business risk matrix that documents potential opportunities and relevant challenges. These risks are reviewed by theme and corresponding actions and mitigation measures are proposed. The aim of the business risk matrix is to help Nexa enable local development and open dialogue and develop a social action strategy. The process of defining the social action strategy includes:

 

· A characterization process so that the local social context and its relationship with the business are better understood and can guide the definition of a strategic agenda;

 

· Strategy development with a long term vision; and

 

· Preparation of the investment plan with definition of actions for implementation in the medium/long term.

 

These social management tools are supported by a 2015 Social Characterization Plan completed to increase the understanding of the local socio-economic environment, the salient issues to the community, a vision and actions for targeted activities, an investment plan and roadmap to improve socio-economic conditions. The 2015 Social Characterization Plan is a comprehensive research and evidenced based document, which draws upon secondary and primary data (i.e., community surveys and stakeholder interviews). As described above, the Local Development Plan (LDP) was elaborated through a process of studies and consultations with the public in 2017, which guide the portfolio of Nexa social projects at the Vazante Operation.

 

In the SLR QP’s opinion the grievance mechanism in place and the social management programs and tools for the Vazante Operations, are adequate to address potential issues related to local communities.

 

 

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17.4.3 Labour and Working Conditions

 

Corporately, Nexa has affirmed its commitment to safe and positive labour and working conditions. The relevant sustainable development targets identified by Nexa include, but are not limited to:

 

· Achieving full and productive employment and decent work for all women and men, including young people and persons with disabilities, and equal pay for work of equal value by 2030.

 

· Protecting labour rights and promote safe and secure working environments for all workers, including migrant workers, in particular migrant women, and persons in precarious employment.

 

Across all its operations, Nexa reports that 100% of its workers in Brazil are covered by collective bargaining units. At the Vazante Operation, employees are covered by various collective agreements depending on their role and type of employment. Each of these are valid to October 2020 with some expiring by April 2022. Vazante employs 966 employees with a smaller number of interns (approximately 17) and apprentices (approximately 29). According to the 2015 Social Characterization Plan, the majority of direct workers were located within the local community.

 

Nexa has adopted OHS policies to ensure the protection and promotion of the safety, human health, and welfare of employees. Corporately, Nexa reports on its health and safety performance and highlights safety as its greatest asset. Several corporate initiatives are aimed at promoting safety, ensuring workers and contractors are trained, and that processes are in place to address any incidents that arise. Nexa has a management standard that outlines the process to communicate, classify, analyze, and record potential accidents (near misses) and accidents in order to improve health and safety measures. Nexa also reports on the health and safety performance at all of their sites.

 

At the Vazante Operation, the Critical Safety Analysis in 2019 indicates that in both 2018 and 2019 there were no fatal accidents and that overall, the health and safety performance was similar in both years (with some small improvements in 2019 as compared to 2018). There were two serious injuries in 2019 (compared to three in 2018), and 18 other events with injuries in 2019 and 2018.

 

Corporately, Nexa has stated its commitment to internationally recognized human rights and prohibits any violation of human rights in its operations and suppliers. Suppliers are asked to provide information regarding both social responsibility and human rights preservation. Nexa reported that in 2019, there were no complaints of non-compliance with any requirements related to human rights impacts, across all of its operations. Furthermore, Nexa is also seeking to review all outside suppliers for their conformity with human rights ethics. As of 2019, approximately half of its suppliers had been reviewed, with no known records of any human rights violations.

 

There are procedures in place for employees and contractors to report grievances and ethical violations, including directly to management, via telephone and online. At the time of writing, there were no specific reports on the number of grievances or ethical violations relevant to the Vazante Operation.

 

Employees working underground shifts work for six days in a row. Each daily shift is comprised of six hours underground with one hour at the surface. Following a six day shift, employees are off for three days, which provides staff with sufficient opportunities to rest between scheduled work activities. Nexa has tried to hire from the local workforce when possible, both for skilled and unskilled workers. Outreach is conducted to the local community through social and employment programs. According to the distribution of employees presented in the 2015 Social Characterization Plan, approximately 95% of the direct workforce is sourced from the State of Minas Gerais, and at least 50% of the direct workforce comes from the Vazante municipality.

 

 

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Employees have access to a number of benefits including paid vacations and holidays, financial bonuses, health, education, overtime, living allowance, and other employment bonuses.

 

17.4.4 Community Health and Safety

 

Corporately, Nexa has made several commitments to improve community health and safety, as well as the overall well being of community members. The municipality of Vazante has identified waste removal and treatment and access to clean drinking water as major issues. Nexa has also identified these as areas for targeted action to help communities build the required infrastructure and facilitate these development projects. Solid waste management is one of two major priorities for Nexa at the Vazante Operation, as documented in it’s 2017 Community Relations Plan. This project will support the development of recycling and waste collection, sorting, and management facilities and services. The second priority is economic development and diversification, in recognition of the growth that has occurred at Vazante in step with the development of the Vazante Operation. Nexa has targeted a number of social activities to support local education and training as well as explore other economic opportunities such as tourism in order to diversify the local economy.

 

Nexa supports social health and community well being through a number of other initiatives which align with specific axes of operation. These include, but are not limited to:

 

· Children and Youth

 

o Partnership for the Valorization of Education

 

· Public Management and Social Participation

 

o We Are All

 

o Citizen Initiative

 

o Social Agenda

 

· Socio-Environmental

 

o Environmental Education Programs

 

o People Caring for the Waters

 

o Good Water

 

o Recycling and Composting Programs

 

· Economic Development

 

o Enjoy – Support for Public Management – Tourism Plan

 

o Good Rural Practices

 

o Qualification of Local Entrepreneurs

 

Collectively, these projects seek to improve local socio-economic conditions and support a more diverse and educated workforce.

 

Due to the COVID-19 pandemic, in 2020, there was a re-assessment of the proposed projects and adequacy of Nexa's social portfolio, ensuring compliance with the health protocols for the safety of Nexa employees and the community. The efforts were focused on preventing the spread of COVID-19.

 

 

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17.4.5 Land Acquisition and Involuntary Resettlement

 

At the time of writing, there does not appear to be any land acquisition or involuntary resettlement associated with the Vazante Operation. Therefore, SLR is of the opinion that PS5 is not applicable.

 

17.4.6 Indigenous Peoples

 

There are no Indigenous peoples in the vicinity of the Vazante Operation. Therefore, SLR is of the opinion that PS7 does not appear to be applicable.

 

17.4.7 Cultural Heritage

 

There is a management standard specific to the Vazante Operation (PGU-VZ-HSM-MOM-005-EN) which outlines guidelines in the case of occurrence of fossils, or materials of archaeological, prehistoric, historic, or artistic interest in the underground cavities or properties related to the Vazante Operation. This document provides clear guidelines for site operators should any such articles of interest be discovered in accordance with local legislation and other requirements.

 

17.4.8 Conclusions and Recommendations

 

SLR’s review of social aspects indicates that, at present, Nexa’s Vazante Operation is a positive contribution to sustainability and community well being. Nexa has established and continues to implement its various corporate policies, procedures, and practices in a manner consistent with relevant IFC PSs. Nexa has, and continues to make, a positive contribution to the communities most affected by the site operations and has done a thorough job in documenting potential effects on stakeholders and protecting the rights, health, and safety of its employees.

 

At this time, there are no specific recommendations to improve Nexa’s social performance at the Vazante Operation. Outreach, dialogue, and clear documentation should continue, particularly through the COVID-19 pandemic.

 

17.5 Mine Closure Requirements

 

17.5.1 Regulatory Requirements

 

Mining companies must submit studies to the environmental authorities related to the mitigation and compensation measures to obtain an LI. These studies must address the reclamation and decommissioning of the mined areas, describing the measures to be implemented throughout the mining process in order to prevent severe degradation of the area and to minimise impacts on the environment.

 

The decommissioning plan for a project must also be filed with the ANM for purposes of evaluation and determination of further measures and requirements in relation to the efficiency and safety of the mining activities.

 

Approval for mine closure is granted by the MME when the applicant can prove compliance with the decommissioning plan, especially environmental conditions.

 

The mining regulatory norm NRM No. 20/2001 establishes administrative and operational procedures in case of mine closure (definitive cessation), suspension (temporary cessation), and resumption of mining operations. NRM No. 20/2001 also outlines the content requirements of the Mine Closure Plan.

 

 

 

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The mining regulatory norm NRM No. 21/2001 establishes administrative and operational procedures in case of rehabilitation of mined and impacted areas. According to this norm, rehabilitation projects must be prepared by legally qualified technicians and submitted to the ANM for evaluation.

 

In the State of Minas Gerais there are several norms dealing with the environmental aspects of mining and its industrial units. For the preparation of the Mine Closure Plan, the Normative Resolution COPAM 127/2008 must be considered, which establishes guidelines and procedures for environmental assessment of the mine closure phase. This norm conceptualizes mine closure as “a process that covers the entire mine life, from the stage of economic feasibility studies to the closure of the mining activity, including the closure, rehabilitation and future use of the impacted area”.

 

The mine closure must be planned from the beginning of the project. The essential objectives of the mine closure are as follows:

 

· Ensure that environmental, social, and economic impacts are mitigated after closure.

 

· Maintain the project area in safe and stable conditions through the implementation of the best control and monitoring techniques.

 

· Adjust the area impacted by mining activities for future use in a manner consistent with the socio-environmental and economic characteristics of the area of influence of the project.

 

The mining company must file the Mine Closure Plan with the state environmental agency, at least two years prior to closure. The same obligation applies to companies that have their registrations and authorizations annulled, revoked, or declared expired by the ANM, or companies addressing closure of an abandoned mine site. For projects classified as Class 5 and Class 6, a public hearing must be held in the municipality where the project is located 180 days after submitting the Mine Closure Plan to the environmental agency, in order to present it to interested parties and gather suggestions and opinions regarding closure activities.

 

In the event that mining activities need to be temporarily suspended due to fortuitous events, natural disasters, technical impediments, economic problems, or court decisions, the mining company must communicate the situation to the environmental agency and present a detailed report addressing the mine conditions, covering:

 

· The description of the current situation in the area, with an emphasis on physical and biological aspects.

 

· The definition of the actions that will be carried out during the temporary suspension, aiming at maintaining the safety conditions of the mined area and existing structures, the continuity of environmental rehabilitation, and the definition of monitoring parameters and frequency.

 

· The schedule for implementing the actions.

 

· The cost estimate for carrying out the actions.

 

· The forecast for the resumption of mining activity.

 

Such reports must be filed within 180 days, counted from the date of the interruption of activities. Resumption of activities by the mining company must be communicated to the environmental agency in advance.

 

Other important state regulations are:

 

· The Normative Resolution COPAM No. 62/2002 and its respective amendments (COPAM, 2002), which stipulate the criteria for dams, including closure aspects.

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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· Normative Resolution COPAM No. 76/2004, which stipulates aspects related to interference with permanent preservation areas.

 

· Normative Resolution COPAM No. 127/2008, which establishes the guidelines and procedures for environmental assessment of the mine closure phase, in addition to establishing the mandatory elaboration of the closure plan.

 

· Joint Normative Resolution COPAM / CERH-MG No. 01/2008, which stipulates the classification of water bodies and environmental guidelines for their classification and establishes the conditions and standards for effluent discharges.

 

· Joint Normative Resolution COPAM-CERH No. 02/2010, which institutes the state program for the management of contaminated areas and establishes guidelines and procedures for the protection of soil quality.

 

· Normative Resolution COPAM No. 166/2011, which amends Annex I of DN COPAM-CERH No. 02/2010, establishing reference values for soil quality.

 

Joint Normative Resolution COPAM-CERH No. 01/2008 is the norm that regulates the limit values for the concentration of pollutants from effluents discharged into water bodies in the State of Minas Gerais.

 

17.5.2 Mine Closure Plan

 

The following Mine Closure Plans are approved for the Vazante Operation (Amec, 2017):

 

· Vazante Mine decommissioning plan (conceptual phase) from 2008 and updated in 2013.

 

· Waste rock facility and open pit rehabilitation plan from 2011.

 

· Extremo Norte Mine decommissioning plan (conceptual phase) from 2012.

 

· Former process plant decommissioning plan (executive phase) from 2013.

 

A copy of the most recent Mine Closure Plan titled Detailed Decommissioning Actions Project for Vazante (Golder, 2018) was provided to SLR by Nexa. The Mine Closure Plan was developed with consideration to applicable norms and legal requirements as well as the guideline developed by Votorantim Metais Holding (VMH) for implementation, preparation and contracting closure studies and projects for decommissioning of mines, industrial units and other units that belong to VMH (Guideline PG-VM-HSMQ-040 Revision 2.2).

 

The Mine Closure Plan has been designed to address remediation of the operational areas, and to meet Brazilian engineering requirements for such plans at a conceptual level. The current plan provides the minimum requirements for the effective planning of mine closure activities, including the necessary provisioning of resources. The plan identifies three key phases:

 

· Pre-closure Phase: period of approximately seven years from 2021 to 2027, considering end of operations in 2027. Activities for this period are associated with field surveys, complementary studies, and development of environmental programs for the closure and post-closure phases.

 

· Closure Phase: decommissioning activities to be carried out in 2028 (approximate duration of one year).

 

· Post-closure Phase: period of approximately 10 years from 2019 to 2038 focused on environmental stabilization, monitoring and verification of physical, chemical, biological, and socioeconomic stability and evaluation of performance indicators. It also includes continuous maintenance activities and implementation of potential corrective actions, if required.

 

The Mine Closure Plan for the Vazante Mine covers the following components:

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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· Underground mine.

 

· Mined-out open pits from historical mining activities (Bocaina, Sucuri Central, Morro da Usina, Sucuri South, Portaria, and Cercado).

 

· Waste rock facilities (Depósito N°1 and Cercado).

 

· Antiga and Aroeira TSFs.

 

· Processing plants for willemite and calamine (Plant W and Plant C).

 

· Ancillary infrastructure (administrative and operational support facilities).

 

The Mine Closure Plan for the Extremo Norte Mine covers the following components:

 

· Underground mine.

 

· Mined-out open pits from historical mining activities (3A, 5A and 6A).

 

· Ancillary infrastructure (power distribution, roads, administrative facilities).

 

The Mine Closure Plan assumes most facilities will be dismantled, and equipment removed from the site. Closure of processing plant areas will consist of removal of buildings and structures, implementation of drainage systems and revegetation. Zinc concentrations in the soil are naturally high, and the levels in the plant area reflect the natural concentrations. As a result, no topsoil replacement is anticipated to be required. No remedial recontouring is expected, as the site is flat, can be readily revegetated, and no significant water management issues are expected.

 

Underground openings will be blocked off, and the water table allowed to re-establish. Closure of waste rock dumps (at this time inactive) will involve land contouring, drainage and erosion controls, and revegetation activities.

 

Closure of the Aroeira TSF will involve the following:

 

· Water pumping to remove the tailings pond.

 

· Breaching at the right abutment and construction of outlet channel to allow water drainage during post-closure.

 

· Re-contouring of surface of deposited tailings.

 

· Sealing of the shaft spillway.

 

· Construction of surface drainage channels.

 

· Topsoil placing and revegetation.

 

Closure of the Pilha Garrote DSTSF will involve construction of a surface drainage system, placing of topsoil, and revegetation. The Pilha Garrote DSTSF will undergo progressive reclamation, with the potential to commence it early in the facility lifecycle.

 

The mine closure premise at this time is that the tailings deposited in the TSFs have no potential for release of sulphate and affect the quality of surface water and groundwater in the surroundings.

 

Post-closure monitoring would be undertaken over a 10 year period (conceptually 2029 to 2038), and would include monitoring of the following key areas:

 

· Geotechnical stability every two months for the initial five years and every six months afterwards.

 

· Drainage structures and erosion every two months for the initial five years and every six months afterwards.

 

· Surface water quality and groundwater quality every six months.

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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· Revegetation weekly and quarterly during the first year and every six months afterwards.

 

· Terrestrial and aquatic fauna every six months.

 

17.5.3 Closure Cost Estimate and Financial Assurance for Closure

 

A closure cost estimate was developed and included in the 2018 Mine Closure Plan, which includes detailed cost sheets. The margin of error in the accuracy estimate was stated to be between -30% and 50% (Golder, 2018). The 2018 Mine Closure Plan states that no contingency was included in the cost estimate. The total current value estimated in Brazilian Reais (R$) in 2018 for the remaining LOM is as follows (excluding local taxes):

 

· Pre-closure Phase (2017 to 2027) R$12,780,000 US$2,529,792
   
· Closure Phase (2028) R$234,227,826 US$46,365,234
   
· Post-Closure Phase (2029 to 2038) R$24,204,648 US$4,791,293
   
· Total closure cost R$271,212,474 US$53,686,319

 

SLR used an exchange rate of R$5.0555:US$1.00 (December 10, 2020) to convert the closure cost estimate to US Dollars. The total value of R$271,212,474 corresponds to a present value of R$144,280,435 (US$28,560,211) considering an annual discount rate of 7.83% and disregarding inflation.

 

A financial assurance was provided by Nexa consistent with the internal Corporate Policy PC-COP-GCT-022-EN that establishes general guidelines for decommissioning considering the Asset Retirement Obligation (ARO) procedure and environmental liabilities. The ARO is an accounting procedure that requires companies to recognize the fair value of future obligations for the dismantling and removal of long lived assets, in order to ensure their balance sheets are more accurate. From an environmental perspective, they refer to future obligations to restore/recover the environment to ecological conditions that are similar to those existing before the start of the project or activity. In cases where it is impossible to return to the pre-existing conditions, there is an obligation to carry out compensatory measures to be agreed with the relevant entities.

 

The ARO for the Vazante Operation in 2018 was calculated as R$253,945,481 (US$50,268,330). The remaining R$17,266,993 (US$3,417,989) from the total closure cost correspond to the environmental liabilities.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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18.0 Capital and Operating Costs

 

SLR reviewed capital and operating costs required for mining and processing of Mineral Reserves at the Vazante Operation. Costs were supplied to SLR by Nexa. Vazante Operation consists of an operating mine, therefore, the capital and operating cost estimates were prepared based on recent operating performance and the current operating budget for 2020. SLR considers these cost estimates to be reasonable. All costs in this section are expressed in US dollars.

 

18.1 Capital Costs

 

Sustaining capital costs were estimated by Nexa, with the majority of the costs consisting of mine development and heavy mobile equipment needed to replace the aging fleet. Sustaining capital costs are summarized in Table 18-1.

 

Table 18-1:      Sustaining Capital Cost Estimate
Nexa Resources S.A. – Vazante Polymetallic Operations

 

Category   Sustaining Costs
(US$ millions)
 
Safety, Health & Environmental     4.8  
Heavy Mobile Equipment     53.9  
Expansion     18.5  
Modernization     6.0  
Horizontal Development     94.7  
Vertical Development     23.6  
Sustaining     27.4  
Operational Working Capital     -7.6  
Closure     38.5  
Total     259.9  

 

18.2 Operating Costs

 

Operating costs estimated by Nexa, averaging $68.6 million per year were estimated for mining, processing, and G&A. Operating cost inputs such as labour rates, consumables, and supplies were based on Nexa operating data. A summary of operating costs is provided in Table 18-2.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Table 18-2:      Operating Cost Estimate 

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Parameter     Total LOM
(US$ millions)
    Average Year
(US$ millions/yr)
    LOM Unit Cost
(US$/t)
 
  Mining       447.7       40.7       26.83  
  Processing       222.8       20.3       13.36  
  G&A       84.5       7.7       5.06  
  Total       755.0       68.6       45.25  

 

SLR notes that capital and operating costs are reported in R$, and that the foreign exchange rate R$:US$ has a significant impact on costs.

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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19.0 Economic Analysis

 

The economic analysis contained in this Technical Report Summary is based on the Mineral Reserves, economic assumptions provided by Nexa for the Vazante Operation, and the capital and operating costs as presented in Section 18 of this Technical Report Summary.

 

19.1 Economic Criteria

 

19.1.1 Physicals

 

· Mine life: 11 years (between 2021 and 2031):

 

· Underground ore tonnes mined: 16.684 Mt

 

o Zinc grade: 8.61% Zn

 

o Lead grade: 0.23% Pb

 

o Silver grade: 13.73 g/t Ag

 

· Processed:

 

o Total Ore Feed: 16.684 Mt

 

§ Zinc grade: 8.61% Zn

 

§ Lead grade: 0.23% Pb

 

§ Silver grade: 13.73 g/t Ag

 

o Contained Metal:

 

§ Zinc: 1.437 Mt Zn

 

§ Lead: 0.038 Mt Pb

 

§ Silver: 7.367 Moz Ag

 

o Average LOM Recoveries:

 

§ Zn recovery 83.9%

 

§ Pb recovery 47.2%

 

§ Ag in Pb recovery 42.0%

 

o Recovered Metals:

 

§ Zinc: 1.205 Mt Zn

 

§ Lead: 0.0179 Mt Pb

 

§ Silver: 3.094 Moz Ag

 

o Payable Metals:

 

§ Zinc: 1.138 Mt Zn

 

§ Lead: 0.0158 Mt Pb

 

§ Silver: 2.939 Moz Ag

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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19.1.2 Revenue

 

· Revenue is estimated based on the following LOM average metal prices:

 

o Zinc price: US$2,491/t Zn

 

o Lead price: US$1,960/t Pb

 

o Silver price: US$17.01/oz Ag

 

· Net Revenue includes the benefit of zinc smelting at cost (rather than at commercial third-party terms), due to integration with Nexa’s Três Marias refinery.

 

· Logistics, Treatment and Refining charges:

 

o LOM average Transportation/Logistics charges:

 

§ Zinc concentrate to Três Marias refinery: US$16.7/t concentrate

 

§ Lead concentrate to Asia: US$278.7/t concentrate

 

o Treatment Charges:

 

§ LOM average TC for lead concentrate: US$200.4/t concentrate

 

§ LOM average refined zinc conversion costs at Três Marias: US$477/t

 

o Refining Charges:

 

§ Silver in lead concentrate: US$1.00/oz Ag

 

· LOM Net Revenue after Treatment and Refining charges is US$2,627 million.

 

19.1.3 Capital Costs

 

· LOM sustaining capital costs of US$228.9 million.

 

· Closure costs of US$38.5 million were included at the end of the Mineral Reserves based LOM in year 2032.

 

19.1.4 Operating Costs

 

· LOM unit operating cost average of:

 

o Mine Development: US$7.77/t mined

 

o Underground Mining: US$19.07/t mined

 

  o Processing: US$13.36/t milled

 

  o G&A: US$5.06/t milled

 

· Total unit operating costs of US$45.25/t milled.

 

· LOM operating costs of US$755 million.

 

19.1.5 Taxation and Royalties

 

· Corporate income tax rate in Brazil is 34%.

 

· CFEM royalty rate: 2%.

 

· SLR has relied on a Nexa taxation model for calculation of income taxes applicable to the cash flow.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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19.2 Cash Flow

 

SLR reviewed the Vazante Operation LOM after-tax cash flow model to confirm the economics of the LOM plan. The model does not take into account the following components:

 

· Financing costs

 

· Insurance

 

· Overhead cost for a corporate office

 

A cash flow summary is presented in Table 19-1. All costs are in Q4 2020 US dollars with no allowance for inflation.

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Table 19-1:               After-Tax Cash Flow Summary

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Vazante   Cash Flow Summary   Year 0     Year 1     Year 2     Year 3     Year 4     Year 5     Year 6     Year 7     Year 8     Year 9     Year 10     Year 11  
    Inputs   UNITS   TOTAL     2021     2022     2023     2024     2025     2026     2027     2028     2029     2030     2031     2032  
MINING                                                                                                                
Underground                                                                                                                
Production     '000 tonnes     16,684       1,520       1,520       1,530       1,536       1,530       1,536       1,536       1,540       1,531       1,513       1,391       -  
Zn Grade       %     8.6 %     10.4 %     9.8 %     9.8 %     9.8 %     9.8 %     9.8 %     7.7 %     7.7 %     6.8 %     6.9 %     6.2 %     0.0 %
Pb Grade       %     0.2 %     0.3 %     0.3 %     0.2 %     0.2 %     0.2 %     0.3 %     0.2 %     0.2 %     0.2 %     0.2 %     0.2 %     0.0 %
Cu Grade       %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %
Ag Grade       oz/t     0.44       0.56       0.52       0.54       0.47       0.48       0.50       0.33       0.42       0.43       0.36       0.23       -  
Au Grade       oz/t     -       -       -       -       -       -       -       -             -       -       -       -  
Contained Metal in ROM                                                                                                                
Zn       000 tonnes     1,437       157.6       149.5       149.2       150.0       149.8       149.8       117.9       118.0       104.6       104.4       86.0       -  
Pb       000 tonnes     38       4.0       4.4       3.8       3.4       3.2       4.1        3.2       3.0        3.3       3.2       2.4       -  
Cu       000 tonnes     -       -       -       -       -       -       -       -             -       -       -       -  
Ag       kozs     7,367       850.7       791.4       818.8       721.8       740.4       769.6       511.1       646.9       653.2       540.5       322.1       -  
Au       kozs     -       -       -       -       -       -       -       -             -       -       -       -  
                                                                                                                 
PROCESSING                                                                                                                
Mill Feed       '000 tonnes     16,684       1,520       1,520       1,530       1,536       1,530       1,536       1,536       1,540       1,531       1,513       1,391       -  
Head grade                                                                                                                
Zn Grade       %     8.6 %     10.4 %     9.8 %     9.8 %     9.8 %     9.8 %     9.8 %     7.7 %     7.7 %     6.8 %     6.9 %     6.2 %     0.0 %
Pb Grade       %     0.2 %     0.3 %     0.3 %     0.2 %     0.2 %     0.2 %     0.3 %     0.2 %     0.2 %     0.2 %     0.2 %     0.2 %     0.0 %
Cu Grade       %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %     0.0 %
Ag Grade       oz/t     0.44       0.56       0.52       0.54       0.47       0.48       0.50       0.33       0.42       0.43       0.36       0.23       -  
Au Grade       oz/t     -       -       -       -       -       -       -       -             -       -       -       -  
Contained Zn       '000 tonnes     1,437       157.6       149.5       149.2       150.0       149.8       149.8       117.9       118.0       104.6       104.4       86.0       -  
Contained Pb       '000 tonnes     38       4.0       4.4       3.8       3.4       3.2       4.1        3.2       3.0        3.3       3.2       2.4       -  
Contained Cu       '000 tonnes     -       -       -       -       -       -       -       -             -       -       -       -  
Contained Ag       koz     7,367       850.7       791.4       818.8       721.8       740.4       769.6       511.1       646.9       653.2       540.5       322.1       -  
Contained Au       koz     -       -       -       -       -       -       -       -             -       -       -       -  
Net Recovery                                                                                      
Zn Recovery       %     120527.5 %     135       127       127       128       128       128       97       97       85       85       69       -  
Pb Recovery       %     1794.4 %     2       2       2       2       2       2       2       1       2       2       1       -  
Cu Recovery       %     0.0 %     -       -       -       -       -       -       -        -       -       -       -       -  
Ag Recovery       %     309396.5 %     357       332       344       303       311       323       215       272       274       227       135       -  
Concentrate Production                                                                                                                
Zn Concentrate       '000 tonnes     3,090       347.3       326.9       325.9       327.7       327.4       327.2       248.8       248.9       217.2       217.0       176.2       -  
Zn       %     39.00 %     39.0 %     39.0 %     39.0 %     39.0 %     39.0 %     39.0 %     39.0 %     39.0 %     39.0 %     39.0 %     39.0 %     0.0 %
Pb Concentrate       '000 tonnes     72       7.6       8.3       7.1       6.4       6.1       7.7       6.1       5.7       6.3       6.1       4.6       -  
Pb       %     25.00 %     25.0 %     25.0 %     25.0 %     25.0 %     25.0 %     25.0 %     25.0 %     25.0 %     25.0 %     25.0 %     25.0 %     0.0 %
Ag       oz/t     43.1       47.2       40.0       48.3       47.6       51.2       42.0       35.4       47.9       43.8       37.3       29.6       -  
Zn equivalent       kt /year     1,241       140.2       131.7       130.8       130.8       130.6       131.3       99.7       100.0       87.8       87.4       70.5       -  
                                                                                                                 
REVENUES                                                                                  
Metal Prices                                                                                                                
Zn price       US$/t   $ 2,463.81     $ 2,219.00     $ 2,298.00     $ 2,539.00     $ 2,720.00     $ 2,928.00     $ 2,449.00     $ 2,449.00     $ 2,449.00     $ 2,449.00     $ 2,449.00     $ 2,449.00     $ 2,449.00  
Pb price       US$/t   $ 1,927.46     $ 1,950.25     $ 1,898.00     $ 1,957.00     $ 2,039.00     $ 2,247.00     $ 1,910.00     $ 1,910.00     $ 1,910.00     $ 1,910.00     $ 1,910.00     $ 1,910.00     $ 1,910.00  
Cu price       US$/t   $ 6,573.44     $ 6,070.50     $ 6,137.00     $ 6,277.00     $ 6,351.00     $ 6,639.00     $ 6,627.00     $ 6,627.00     $ 6,627.00     $ 6,627.00     $ 6,627.00     $ 6,627.00     $ 6,627.00  
Ag price       US$/oz   $ 16.92     $ 19.05     $ 17.11     $ 16.95     $ 16.40     $ 16.40     $ 16.87     $ 16.87     $ 16.87     $ 16.87     $ 16.87     $ 16.87     $ 16.87  
Au price       US$/oz   $ 1,516.08     $ 1,900.50     $ 1,613.00     $ 1,553.00     $ 1,466.00     $ 1,466.00     $ 1,500.00     $ 1,500.00     $ 1,500.00     $ 1,500.00     $ 1,500.00     $ 1,500.00     $ 1,500.00  
FX Rate       BRL/USD   $ 4.81     $ 5.05     $ 4.84     $ 4.85     $ 4.80     $ 4.80     $ 4.80     $ 4.80     $ 4.80     $ 4.80     $ 4.80     $ 4.80     $ 4.80  
Payable Metal                                                                                      
Zn       '000 tonnes     1,138       127.9       120.4       120.0       120.7       120.6       120.5       91.6       91.6       80.0       79.9       64.9       -  
Pb       '000 tonnes     16       1.7       1.8       1.6       1.4       1.3       1.7       1.3       1.2       1.4       1.3       1.0       -  
Ag       kozs     2,939       339.4       315.8       326.7       288.0       295.4       307.1       203.9       258.1       260.6       215.7       127.9       -  
Zn Metal                                                                                                                
Selling Price       US$/t conc   $ 2,263.00     $ 2,016.12     $ 2,065.60     $ 2,306.41     $ 2,483.89     $ 2,692.31     $ 2,213.35     $ 2,213.10     $ 2,218.98     $ 2,217.71     $ 2,205.22     $ 2,178.96     $ -  
Volume       '000 tonnes     1,138       127.9       120.4       120.0       120.7       120.6       120.5       91.6       91.6       80.0       79.9       64.9       -  
Revenues       US$ '000   $ 2,575,310     $ 257,865     $ 248,659     $ 276,749     $ 299,742     $ 324,567     $ 266,677     $ 202,763     $ 203,344     $ 177,378     $ 176,201     $ 141,365     $ -  
Pb Concentrate                                                                                                                
Selling Price       US$/t conc   $ 887.36     $ 1,025.56     $ 822.10     $ 960.58     $ 942.45     $ 1,046.34     $ 856.76     $ 757.18     $ 945.35     $ 884.08     $ 785.87     $ 666.96     $ -  
Concentrate       '000 tonnes     72       7.6       8.3       7.1       6.4       6.1       7.7       6.1       5.7       6.3       6.1       4.6       -  
Revenues       US$ '000   $ 63,692     $ 7,758     $ 6,828     $ 6,838     $ 6,007     $ 6,355     $ 6,590     $ 4,589     $ 5,362     $ 5,533     $ 4,780     $ 3,051     $ -  
(=) TOTAL Gross Revenues       US$ '000   $ 2,639,002     $ 265,623     $ 255,486     $ 283,587     $ 305,749     $ 330,922     $ 273,266     $ 207,353     $ 208,706     $ 182,912     $ 180,981     $ 144,416     $ -  
Zn Concentrate       %     98 %     97 %     97 %     98 %     98 %     98 %     98 %     98 %     97 %     97 %     97 %     98 %     0 %
Pb Concentrate       %     2 %     3 %     3 %     2 %     2 %     2 %     2 %     2 %     3 %     3 %     3 %     2 %     0 %
( - ) Royalties       US$ '000   $ 12,093     $ 1,098     $ 1,119     $ 1,122     $ 1,117     $ 1,122     $ 1,129     $ 1,089     $ 1,106     $ 1,106     $ 1,084     $ 1,003     $ -  
CFEM       US$ '000   $ 12,093     $ 1,098     $ 1,119     $ 1,122     $ 1,117     $ 1,122     $ 1,129     $ 1,089     $ 1,106     $ 1,106     $ 1,084     $ 1,003     $ -  
                                                                                                                 

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

Technical Report Summary - February 15, 2021

 

19-4

 

 

 

 

        Cash Flow
Summary
  Year 0     Year 1      Year 2      Year 3      Year 4      Year 5      Year 6      Year 7      Year 8      Year 9      Year  10     Year 11   
Vazante   Inputs   UNITS   TOTAL     2021     2022      2023     2024     2025     2026     2027     2028     2029     2030     2031     2032  
(=) TOTAL Net Revenues       US$ '000   $ 2,626,909     $ 264,525     $ 254,367     $ 282,465     $ 304,632     $ 329,800     $ 272,138     $ 206,264     $ 207,601     $ 181,806     $ 179,898     $ 143,414     $ -  
                                                                                                                 
NSR       US$/t ROM   $ 153.2     $ 169.8     $ 162.8     $ 179.8     $ 193.4     $ 210.6     $ 172.1     $ 130.3     $ 130.9     $ 115.1     $ 115.2     $ 99.9     $ -  
                                                                                                                 
OPERATING COST                                                                                                                
Mining (Underground)       US$ '000   $ 318,157     $ 27,715     $ 28,896     $ 28,975     $ 29,309     $ 29,248     $ 29,305     $ 29,308     $ 29,353     $ 29,254     $ 29,060     $ 27,733     $ -  
Secondary Development       US$ '000   $ 129,557     $ 13,353     $ 14,115     $ 16,155     $ 17,457     $ 17,034     $ 12,035     $ 18,768     $ 12,595     $ -     $ 8,046     $ -     $ -  
Processing + Tailings       US$ '000   $ 222,822     $ 19,412     $ 20,239     $ 20,301     $ 20,538     $ 20,492     $ 20,535     $ 20,537     $ 20,571     $ 20,496     $ 20,350     $ 19,349     $ -  
G&A       US$ '000   $ 84,498     $ 7,350     $ 7,664     $ 7,657     $ 7,728     $ 7,728     $ 7,728     $ 7,728     $ 7,728     $ 7,728     $ 7,728     $ 7,728     $ -  
Total Operating Cost       US$ '000   $ 755,035     $ 67,831     $ 70,914     $ 73,088     $ 75,033     $ 74,503     $ 69,603     $ 76,342     $ 70,247     $ 57,479     $ 65,185     $ 54,810     $ -  
Mining (Underground)       US$ /t proc   $ 19.1     $ 18.2     $ 19.0     $ 18.9     $ 19.1     $ 19.1     $ 19.1     $ 19.1     $ 19.1     $ 19.1     $ 19.2     $ 19.9     $ -  
Secondary Development       US$ /t proc   $ 7.8     $ 8.8     $ 9.3     $ 10.6     $ 11.4     $ 11.1     $ 7.8     $ 12.2     $ 8.2     $ -     $ 5.3     $ -     $ -  
Processing + Tailings       US$ /t proc   $ 13.4     $ 12.8     $ 13.3     $ 13.3     $ 13.4     $ 13.4     $ 13.4     $ 13.4     $ 13.4     $ 13.4     $ 13.4     $ 13.9     $ -  
G&A       US$ /t proc   $ 5.1     $ 4.8     $ 5.0     $ 5.0     $ 5.0     $ 5.0     $ 5.0     $ 5.0     $ 5.0     $ 5.0     $ 5.1     $ 5.6     $ -  
Total Operating Cost       US$ /t proc   $ 45.3     $ 44.6     $ 46.6     $ 47.8     $ 48.8     $ 48.7     $ 45.3     $ 49.7     $ 45.6     $ 37.5     $ 43.1     $ 39.4     $ -  
                                                                                                                 
Cost/Zn eq.       US$ /t Zn eq.   $ 608.5     $ 483.8     $ 538.5     $ 559.0     $ 573.5     $ 570.5     $ 530.0     $ 765.8     $ 702.2     $ 654.5     $ 746.0     $ 777.1     $ -  
                                                                                                                 
Selling Expenses       US$ '000   $ 71,010     $ 6,405     $ 6,883     $ 7,290     $ 7,551     $ 7,462     $ 7,909     $ 6,074     $ 5,966     $ 5,572     $ 5,519     $ 4,380     $ -  
Zn Concentrate       US$ '000   $ 51,004     $ 4,297     $ 4,568     $ 5,306     $ 5,775     $ 5,769     $ 5,765     $ 4,384     $ 4,385     $ 3,827     $ 3,823     $ 3,105     $ -  
Pb Concentrate       US$ '000   $ 20,005     $ 2,108     $ 2,315     $ 1,984     $ 1,776     $ 1,693     $ 2,144     $ 1,689     $ 1,581     $ 1,744     $ 1,695     $ 1,275     $ -  
                                                                                                                 
OOR       US$ '000   $ 58,578     $ 1,415     $ 1,057     $ 632     $ -     $ 486     $ 2,094     $ 2,898     $ 4,384     $ 19,443     $ 6,727     $ 19,443     $ -  
                                                                                                                 
(=) EBITDA       US$ '000   $ 1,742,285     $ 188,874     $ 175,514     $ 201,454     $ 222,048     $ 247,350     $ 192,531     $ 120,951     $ 127,003     $ 99,313     $ 102,467     $ 64,781     $ -  
EBITDA Margin       %     66 %     71 %     69 %     71 %     73 %     75 %     70 %     58 %     61 %     54 %     57 %     45 %     0 %
                                                                                                                 
CAPITAL COST                                                                                                                
                                                                                                                 
Initial Capital Cost                                                                                                                
Safety, Health & Environmental       US$ '000     4,840       2,033       828       621       733       625       -       -       -       -       -       -       -  
Heavy Mobile Equipment       US$ '000     53,854       3,161       2,582       6,881       10,561       8,873       6,423       4,476       4,538       5,207       1,152       -       -  
Expansion       US$ '000     18,497       2,202       16,295       -       -       -       -       -       -       -       -       -       -  
Modernization       US$ '000     6,007       3,230       1,819       598       255       104       -       -       -       -       -       -       -  
                                                                                                                 
(=) TOTAL Capex       US$ '000     83,198       10,627       21,525       8,100       11,549       9,602       6,423       4,476       4,538       5,207       1,152       -       -  
                                                                                                                 
Operating Capital Cost                                                                                                                
Mine Development       US$ '000   $ 118,315     $ 21,831     $ 18,095     $ 14,294     $ 14,363     $ 14,078     $ 19,194     $ 5,485     $ 5,665     $ -     $ 5,310     $ -     $ -  
Sustaining infrastructure       US$ '000   $ 27,413     $ 10,913     $ 4,723     $ 5,646     $ 274     $ 262     $ -     $ -     $ 402     $ 5,193     $ -     $ -     $ -  
Closure and Other       US$ '000   $ 38,491     $ -     $ -     $ -     $ -     $ -     $ -     $ -     $ -     $ -     $ -     $ -     $ 38,491  
Operational Working Capital       US$ '000   $ -7,614     $ 6,337     $ (581 )   $ 1,540     $ 1,209     $ 1,379     $ (3,159 )   $ (3,612 )   $ 74     $ (1,413 )   $ (106 )   $ (2,004 )   $ (7,278 )
(=) TOTAL Operating Capital Cost       US$ '000   $ 176,605     $ 39,081     $ 22,237     $ 21,480     $ 15,846     $ 15,719     $ 16,035     $ 1,873     $ 6,141     $ 3,779     $ 5,204     $ (2,004 )   $ 31,213  
                      -       -       -       -       -       -       -       -       -       -       -       -  
CASH FLOW             NPV @ 9.0%                                                                                                  
(+) Revenues       US$ '000   $ 1,782,296     $ 265,623     $ 255,486     $ 283,587     $ 305,749     $ 330,922     $ 273,266     $ 207,353     $ 208,706     $ 182,912     $ 180,981     $ 144,416     $ -  
( - ) Royalties       US$ '000   $ 7,846     $ 1,098     $ 1,119     $ 1,122     $ 1,117     $ 1,122     $ 1,129     $ 1,089     $ 1,106     $ 1,106     $ 1,084     $ 1,003     $ -  
( - ) Mining Costs       US$ '000   $ 296,327     $ 41,068     $ 43,011     $ 45,130     $ 46,766     $ 46,282     $ 41,340     $ 48,077     $ 41,948     $ 29,254     $ 37,106     $ 27,733     $ -  
( - ) Processing Costs       US$ '000   $ 143,787     $ 19,412     $ 20,239     $ 20,301     $ 20,538     $ 20,492     $ 20,535     $ 20,537     $ 20,571     $ 20,496     $ 20,350     $ 19,349     $ -  
( - ) G&A       US$ '000   $ 54,432     $ 7,350     $ 7,664     $ 7,657     $ 7,728     $ 7,728     $ 7,728     $ 7,728     $ 7,728     $ 7,728     $ 7,728     $ 7,728     $ -  
( - ) Selling Expenses       US$ '000   $ 47,111     $ 6,405     $ 6,883     $ 7,290     $ 7,551     $ 7,462     $ 7,909     $ 6,074     $ 5,966     $ 5,572     $ 5,519     $ 4,380     $ -  
( +/- ) OOR       US$ '000   $ -28,558     $ -1,415     $ -1,057     $ -632     $ -     $ -486     $ -2,094     $ -2,898     $ -4,384     $ -19,443     $ -6,727     $ -19,443     $ -  
(=) EBITDA       US$ '000   $ 1,204,234     $ 188,874     $ 175,514     $ 201,454     $ 222,048     $ 247,350     $ 192,531     $ 120,951     $ 127,003     $ 99,313     $ 102,467     $ 64,781     $ -  
                                                                                                                 
( - ) Capex (net of taxes)       US$ '000   $ 62,624     $ 10,627     $ 21,525     $ 8,100     $ 11,549     $ 9,602     $ 6,423     $ 4,476     $ 4,538     $ 5,207     $ 1,152     $ -     $ -  
( - ) Sustaning Capex (net of taxes)       US$ '000   $ 111,143     $ 32,744     $ 22,818     $ 19,940     $ 14,637     $ 14,340     $ 19,194     $ 5,485     $ 6,067     $ 5,193     $ 5,310     $ -     $ -  
( - ) Closure and Other       US$ '000   $ 14,288     $ -     $ -     $ -     $ -     $ -     $ -     $ -     $ -     $ -     $ -     $ -     $ 38,491  
( +- ) Operational Working Capital       US$ '000   $ 402     $ 6,337     $ (581 )   $ 1,540     $ 1,209     $ 1,379     $ (3,159 )   $ (3,612 )   $ 74     $ (1,413 )   $ (106 )   $ (2,004 )   $ (7,278 )
(=) Pre-Tax Cashflow       US$ '000   $ 1,016,581     $ 151,841     $ 130,590     $ 174,954     $ 197,070     $ 224,788     $ 163,755     $ 107,378     $ 116,472     $ 87,499     $ 95,899     $ 62,777     $ (45,769 )
                                                                                                                 
( - ) Income Tax       US$ '000   $ 364,787     $ 62,635     $ 56,430     $ 64,065     $ 69,776     $ 77,263     $ 57,762     $ 33,110     $ 35,126     $ 25,898     $ 27,315     $ 4,338     $ -  
(=) After-Tax Cashflow       US$ '000   $ 651,794     $ 89,205     $ 74,160     $ 110,889     $ 127,294     $ 147,524     $ 105,994     $ 74,268     $ 81,347     $ 61,601     $ 68,584     $ 58,439     $ (45,769 )
                                                                                                                 
PROJECT ECONOMICS             period       0.5       1.5       2.5       3.5       4.5       5.5       6.5       7.5       8.5       9.5       10.5       11.5  
Discount factor   9.00 %               0.96       0.88       0.81       0.74       0.68       0.62       0.57       0.52       0.48       0.44       0.40       0.37  
Pre-Tax                                                                                                                
Pre-tax NPV at 8.00% discounting   8.00 % US$ '000   $ 1,054,809     $ 146,109     $ 116,352     $ 144,333     $ 150,535     $ 158,989     $ 107,242     $ 65,112     $ 65,395     $ 45,489     $ 46,162     $ 27,980     $ (18,889 )
                                                                                                                 
Pre-tax NPV at 9.00% discounting   9.00 % US$ '000   $ 1,016,581     $ 145,437     $ 114,755     $ 141,045     $ 145,757     $ 152,529     $ 101,941     $ 61,326     $ 61,027     $ 42,061     $ 42,292     $ 25,399     $ (16,989 )
Pre-tax NPV at 10.00% discounting   10.00 % US$ '000   $ 980,593     $ 144,774     $ 113,193     $ 137,862     $ 141,171     $ 146,388     $ 96,947     $ 57,791     $ 56,987     $ 38,919     $ 38,778     $ 23,077     $ (15,295 )
After-Tax                                                                                                                
After-tax NPV at 8.00% discounting   8.00 % US$ '000   $ 677,289     $ 85,838     $ 66,075     $ 91,481     $ 97,235     $ 104,342     $ 69,414     $ 45,035     $ 45,673     $ 32,025     $ 33,014     $ 26,047     $ (18,889 )
After-tax NPV at 9.00% discounting   9.00 % US$ '000   $ 651,794     $ 85,443     $ 65,168     $ 89,397     $ 94,149     $ 100,102     $ 65,983     $ 42,416     $ 42,623     $ 29,612     $ 30,246     $ 23,644     $ (16,989 )
After-tax NPV at 10.00% discounting   10.00 % US$ '000   $ 627,816     $ 85,054     $ 64,281     $ 87,379     $ 91,187     $ 96,072     $ 62,751     $ 39,971     $ 39,801     $ 27,400     $ 27,733     $ 21,482     $ (15,295 )

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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19.2.1 Cash Flow Analysis

 

Mine economics have been evaluated using the discounted cash flow method, using mid-year discounting convention, and taking into account annual processed tonnages and zinc, lead, and silver grades. The associated process recovery, zinc, and lead concentrate grades, metal prices, operating costs, refining and transportation charges, royalties, and capital expenditures were also considered.

 

The economic analysis confirmed that the Vazante Mineral Reserves are economically viable. The pre-tax net present value (NPV) at a 9% base discount rate is US$1,017 million and the after-tax NPV at a 9% base discount is US$652 million.

 

The summary of the results of the cash flow analysis is presented in Table 19-2.

 

Table 19-2:                 Cash Flow Analysis

Nexa Resources S.A. – Vazante Polymetallic Operations

 

Item   Discount Rate   Units   Value  
Pre-tax NPV at 8% discount   8%   US$ million   1,055  
               
Pre-tax NPV at 9% discount   9%   US$ million   1,017  
               
Pre-tax NPV at 10% discount   10%   US$ million   981  
               
After-Tax NPV at 8% discount   8%   US$ million   677  
               
After-Tax NPV at 9% discount   9%   US$ million   652  
               
After-tax NPV at 10% discount   10%   US$ million   628  

 

The undiscounted pre-tax cash flow is US$1,468 million, and the undiscounted after-tax cash flow is US$954 million. For this cash flow analysis, the internal rate of return (IRR) and payback are not applicable as there is no negative initial cash flow (no initial investment to be recovered).

 

19.3 Sensitivity Analysis

 

Project risks can be identified in both economic and non-economic terms. Key economic risks were examined by running cash flow sensitivities on after-tax NPV at an 9% discount rate. The following items were examined:

 

· Metal prices

 

· Head grade

 

· Metallurgical recovery

 

· Operating costs, and

 

· Capital costs

 

After-tax sensitivity over the base case has been calculated for -20% to +20% (for head grade), -10% to +5% (for recoveries), -20% to +20% (for metal prices), and -5% to +15% (operating costs and capital costs) variations to determine the most sensitive parameter of this project. The sensitivities are shown in Table 19-3 and Figure 19-1.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Table 19-3:                 After-Tax Sensitivity Analysis

Nexa Resources S.A. – Vazante Polymetallic Operations

 

    Head Grade   NPV at 9%
(US$ million)
 
80%   Zn:6.89% Pb:0.18% Ag:10.99 g/t   389  
90%   Zn:7.75% Pb:0.21% Ag:12.36 g/t   520  
100%   Zn:8.61% Pb:0.23% Ag:13.73 g/t   652  
110%   Zn:9.47% Pb:0.25% Ag:15.11 g/t   785  
120%   Zn:10.33% Pb:0.27% Ag:16.48 g/t   920  

 

    Zn Recovery   NPV at 9%
(US$ million)
 
90%   75.9%   536  
98%   79.7%   594  
100%   83.9%   652  
103%   86.0%   681  
105%   88.1%   709  

 

    Metal Prices   NPV at 9%
(US$ million)
 
80%   Zn:$0.90/lb Pb:$0.71/lb Ag:$13.61/oz   387  
90%   Zn:$1.02/lb Pb:$0.80/lb Ag:$15.31/oz   520  
100%   Zn:$1.13/lb Pb:$0.89/lb Ag:$17.20/oz   652  
110%   Zn:$1.24/lb Pb:$0.98/lb Ag:$18.71/oz   783  
120%   Zn:$1.36/lb Pb:$1.07/lb Ag:$20.41/oz   914  

 

    Operating Costs
(US$ million)
  NPV at 9%
(US$ million)
 
95.0%   717   668  
97.5%   736   660  
100.0%   755   652  
107.5%   811   627  
115.0%   868   603  

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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    Total Capital Costs
(US$ million)
  NPV at 9%
(US$ million)
 
95.0%   251   661  
97.5%   258   656  
100.0%   265   652  
107.5%   284   638  
115.0%   304   624  

 

 

 

Figure 19-1:               After-Tax NPV Sensitivity Graph

 

The after-tax NPV is most sensitive to head grade, then to metal prices, followed by recovery, operating costs, and capital costs.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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20.0 Adjacent Properties

 

SLR is not aware of any significant deposits or properties adjacent to the Vazante Operation.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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21.0 Other Relevant Data and Information

 

No additional information or explanation is necessary to make this Technical Report Summary understandable and not misleading.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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22.0 Interpretation and Conclusions

 

SLR offers the following conclusions by area.

 

22.1 Geology and Mineral Resources

 

· Mineral Resources have been estimated for three styles of mineralization – hypogene (willemite) mineralized zones, where mining currently takes place; supergene (calamine) mineralization, located near surface; and tailings contained within the Aroeira TSF.

 

· As prepared by Nexa and adopted by SLR, the Vazante Measured and Indicated Mineral Resources, effective as of December 31, 2020 and exclusive of Mineral Reserves, comprise 6.3 Mt at grades of 6.88% Zn, 0.16% Pb, and 7.1 g/t Ag, containing 432.3 kt Zn, 10.2 kt Pb, and 1.44 Moz Ag. In addition, Inferred Mineral Resources comprise 13.8 Mt, at grades of 6.86% Zn, 0.18% Pb, and 9.5 g/t Ag, containing 950.2 kt Zn, 25.5 kt Pb, and 4.2 Moz Ag.

 

· Mineral Resources have been classified in accordance with the definitions for Mineral Resources in S-K 1300, which are consistent with CIM (2014) definitions.

 

· The geological data and procedures are adequate for the estimation of Mineral Resources and comply with industry standards.

 

· The “Reasonable Prospects for Economic Extraction” requirement of S-K 1300 resource definitions is satisfied by:

 

o Reporting panels that have been created so as to achieve the required spatial continuity, cut-off grade, and minimum width criteria for the underground hypogene mineralization.

 

o Open pit shells for the supergene mineralization.

 

o The use of the original topographical surface as a constraint for the tailings mineralization.

 

· Location data for the supergene and tailings drill holes is stored in a surface UTM coordinate system, while the hypogene drill data has been converted to an underground mine grid coordinate system.

 

22.2 Mining and Mineral Reserves

 

· The Vazante Operation deposits support an average production rate of 1.5 Mtpa over the LOM, producing from 69,000 t Zn per year to 135,000 t Zn per year contained in zinc concentrate depending on head grade.

 

· Deposit geometry and geomechanical properties are amenable to bulk longhole mining methods. The SLS methods used at the Vazante Mine consist of a combination of downholes or VRM where stopes are backfilled with run of mine rock and up-holes or SLOS which are not backfilled.

 

· As prepared by Nexa and adopted by SLR, the Vazante Proven and Probable Mineral Reserves, effective as of December 31, 2020, comprise 16.7 Mt at grades of 8.61% Zn, 0.23% Pb, and 13.7 g/t Ag, containing 1.44 Mt Zn, 38,000 t Pb, and 7.37 Moz Ag.

 

· Mineral Reserves have been classified in accordance with the definitions for Mineral Reserves in S-K 1300, which are consistent with CIM (2014) definitions.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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· Dilution and extraction estimates include:

 

o Dilution – planned dilution for SLS assumes an estimate of the ELOS depending on the dip of the stope, ranging from zero metres to 0.75 m in the hanging wall and zero metres to 0.25 m in the footwall.

 

o Pillars are also used to control stope dilution. These include the use of sill pillars between mining sublevels, island pillars located at the centre of stopes, and rib pillars positioned at the extremities of the stopes to reduce the potential for excess sloughing from the hanging wall contact and control dilution from adjacent filled stopes.

 

o Extraction – initial selection of resources by stope optimization and design, plus additional factors of 83% to 98% by mining method, and 35% to 60% for pillar recovery.

 

· The Vazante Operation requires extreme dewatering to operate, with pumping capacity increasing over time as total mine workings increase in size. The pumping rates in 2020 averaged approximately 12,500 m³/h, which while in excess of recent modelling, is well within the installed pumping capacity of the Vazante Operation (20,000 m3/h).

 

· The second of a two-phase MDP is underway with the water pumping capacity to increase at the bottom of the mine from 10,000 m3/h to 15,000 m³/h to be completed in 2022.

 

22.3 Mineral Processing

 

· Recovery of zinc from silicate minerals is not common, however, processing via flotation works in a manner similar to recovery of zinc from sulphides. Recovery of zinc metal from zinc silicate concentrates, however, is quite different compared to recovery from sulphides, requiring hydrometallurgical processing at a dedicated facility such as Nexa’s Três Marias smelter.

 

· Zinc recovery has been shown to be related to head grade. The head grade of the processing plant feed is forecast to decrease over the remainder of the LOM, therefore, recovery and zinc concentrate production are also forecast to decrease over the remainder of the LOM, even though the ore processing rate is forecast to continue at current rates until the final year in the LOM.

 

· In the SLR QP’s opinion, the use of past operating performance to derive a head grade versus recovery relationship for zinc (and lead) is reasonable and adequate to predict future plant performance for future head grades and ore types similar to those processed in the past few years.

 

· Plant feed is supplemented from time to time with small amounts of willemite tailings recovered from the Aroeira TSF and blended with the fresh ore, however, Nexa is considering increasing the tailings reprocessing rate to up to 10% of plant feed. Pilot plant test work using column flotation has been conducted to assess the possibility of processing tailings separately to improve zinc recovery and results have been positive. Variability test work on samples of tailings from the Aroeira TSF is underway to help evaluate the variability of metallurgical response of the tailings.

 

 

· Nexa has identified calamine resources in the Extremo Norte deposit area and along the strike length, as well as in historical tailings (the Aroeira TSF), and potential calamine resources in other historical tailings deposits. Nexa is conducting test work on calamine mineralization from the Extremo Norte area to try to improve on historical calamine processing performance, which was characterized as challenging with zinc recovery of only 50%.

 

o Bench-scale open circuit rougher-scavenger test work using conventional mechanical cells achieved approximately 23% Zn in concentrate at a recovery of up to 70%. An open circuit cleaner test produced a concentrate grading 39% Zn (the target zinc grade for concentrate being processed at Nexa’s Três Marias smelter) and a recovery of 63%.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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o Pilot plant test work at the Vazante Operation using conventional mechanical cells demonstrated that overall zinc recovery of up to 50% at concentrate grades over 37% was possible. The majority of zinc losses (approximately 60%) were to the fines fraction (< 38 µm) removed prior to flotation and occurring mainly as hemimorphite. Nexa noted that the use of column cells rather than mechanical cells could provide some improvement in yield due to the large proportion of fines in the feed, and that further assessment of collectors and fatty acids was necessary to improve the recovery of hemimorphite.

 

22.4 Environment & Social

 

· No environmental issues were identified from the documentation available for review that could materially impact the ability to extract the Mineral Resources and Mineral Reserves. The Vazante Operation has all the environmental operational licences required for operation according to Brazilian legislation. The approved licences address the authority’s requirements for mining extraction and operation activities. The Vazante Operation has not applied for new permits and SLR is not aware of any new projects or modification to the existing operations triggering permitting processes. Four active Operation Licences are in the process of renewal through COPAM No. 104/1988/059/2016.

 

· The environmental programs defined in the PCAs are an integral part of the Environmental Management System for adoption of measures aimed at the prevention, mitigation, and control of potential environmental impacts resulting from mining activities. Results of the environmental programs including monitoring of water quality, air quality and noise are documented in annual reports submitted to the authorities (SUPRAM-NOR). The SLR QP is not aware of non-compliance issues raised by the authorities. In the SLR QP’s opinion, the environmental management programs for Vazante are adequate to address potential issues related to environmental compliance.

 

· Nexa utilizes an Integrated Dam Management System (referred to as SIGBar) which provides guidelines for document management, monitoring, evaluation, risk analysis, compliance with standards and legislation, training of personnel, operation of structures and other provisions.

 

· Tailings are currently disposed of as filtered tailings at the Pilha Garrote DSTSF. The Aroeira TSF, the former primary location for tailings disposal until August 2019, will remain operational as a water storage facility.

 

· Regular dam safety inspections have visually confirmed that the tailings beach of the Aroeira TSF between the dam and the tailings pond is greater than 40 m.

 

· Dam monitoring consists of instrument measurements and field inspections. Dam monitoring data is reviewed by an external consultant (Geoconsultoria) on a monthly basis. Fortnightly inspections are completed by Nexa personnel and every six months by Geoconsultoria. The latest review by Geoconsultoria that was reviewed by SLR was dated 30 August 2019 (Relatório Técnico CM18-RT57 Rev.0). Geoconsultoria’s report states the dam safety condition is “Satisfactory” without the presence of erosions, cracks, or other features indicative of instability.

 

· A Mine Closure Plan has been developed for all the Vazante Operation components within the context of Brazilian legislation and consideration to the VMH guideline for decommissioning (Guideline PG-VM-HSMQ-040 Revision 2.2). The most recent Mine Closure Plan and cost estimate were completed in January 2018.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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· A social baseline description, assessment of socio-economic impacts, and identification of socio-economic environment programs have been completed as part of the environmental impact assessments carried out to mitigate negative impacts and maximize positive benefits of the Vazante Operations. These components are generally consistent with social impact assessment practices. Nexa has developed and utilizes a number of social management programs and tools to help the it work with the nearby communities (risk analysis matrices, stakeholder tracking, social characterization plan and local development plan). In the SLR QP’s opinion the grievance mechanism in place and the social management programs and tools for the Vazante Operations, are adequate to address potential issues related to local communities.

 

· Nexa hires from the local workforce when possible, both for skilled and unskilled workers. Outreach to the local community is conducted through social and employment programs.

 

· No social issues were identified from the documentation available for review. The review of social aspects indicates that, at present, Nexa’s operations at the Vazante Operation are a positive contribution to sustainability and community wellbeing. Nexa has established and continues to implement its various corporate policies, procedures, and practices in a manner consistent with relevant IFC PSs. Nexa has, and continues to make, a positive contribution to the communities most affected by the site operations and has done a thorough job in documenting potential effects on stakeholders and protecting the rights, health, and safety of its employees.

 

22.5 Costs and Economic Analysis

 

· The LOM operating cost forecast reflects the existing operating status of the Vazante Operation. SLR has reviewed recent operating costs and is of the opinion that the forecast is appropriate for the Vazante Operation.  Nexa also needs to continue assessing operating efficiencies and approaches in efforts to improve operating costs in the different cost centres.

 

· The economics of the Vazante Operation are robust over the LOM, confirming that the Mineral Reserves are economically viable.  The economic analysis indicates an after-tax net present value (NPV), at a 9% base discount rate, of $652 million.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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23.0 Recommendations

 

SLR offers the following recommendations by area.

 

23.1 Geology and Mineral Resources

 

1. The coordinates for all supergene related drill holes be converted into the local mine grid coordinates so that the results from all Mineral Resource estimation activities can then be integrated with any underground mining activities that have been or are planned to be carried out in this area.

 

2. The drill hole dips for the drill holes examined be confirmed by direct visual inspection of the departing drill hole orientation at the drilling face.

 

3. The drill hole data relating to the tailings mineralization be converted into the mine grid coordinate system to more easily integrate the information for the underground mine.

 

23.2 Mining and Mineral Reserves

 

1. In SLR’s opinion high mine dilution at the Vazante Operation is caused in part by the current cable bolting procedure, whereby bolts are installed from the undercut level and fanned into the hanging wall of the stope. The cable bolt coverage of the stope should be improved by drilling the cable bolt holes from a hanging wall access, where the cost can be justified. Additionally, SLR also recommends assessing the production drilling design to reduce the potential for dilution.

 

2. SLR observed secondary breaking on surface during the 2018 site visit. The stope drill patterns should be reviewed with the intent of reducing the level of stope dilution through adjustment of the drill pattern. This may require drilling an additional hole on the hanging wall contact, between the current burden spacing. A reduced explosive charge per hole, using a lower density explosive, would aid to effectively trim the hanging wall contact thereby providing a much cleaner break. The reduced blast vibration impact (a lower peak particle velocity (ppv)) would lead to a lower degree of overbreak on the hanging wall and less dilution.

 

3. Dilution will be an issue in the narrow cut and fill stopes, which are not yet reflected in Mineral Reserves, as the four metre minimum mining width will impact upon every lift taken. A stope width review should be carried out for the planned cut and fill stopes to determine whether the current equipment fleet matches the orebody dimensions.

 

4. Narrow vein equipment should be assessed as soon as possible to have it readily available at the time narrower areas are encountered in the lower levels of the mine.

 

5. A trial test stope using a smaller drill unit in the upper section of the mine should be completed to assess the efficacy and optimize the drilling layouts, as a prerequisite to eventual application of the method on a larger scale in the lower levels of the mine, when a larger portion of the mine production comes from this area.

 

6. The use of a “shanty back” configuration on the hanging wall side of the drift should be evaluated to reduce dilution.

 

7. Given the extreme dewatering that is required to permit ongoing mining, hydrologic monitoring is considered a critical element of operations. Continued calibration of flows is recommended to predict, plan, and install required pumping capacities for the Vazante Operation.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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8. The water table levels should be monitored as planned to help foresee any potential issues and assess mitigation measures that may be required.

 

9. The use of cemented rock fill (CRF) is recommended to enable mining of certain pillars where this is economical. A trade-off analysis would be required in each case.

 

10. The reconciliation results and the stope performance analysis should be used to evaluate stope designs to determine where improvements in mine planning would be most advantageous.

 

23.3 Mineral Processing

 

1. Continue the variability test work and process development on samples of Aroeira willemite tailings to assess the variability of metallurgical response and provide an estimate of overall recovery from the willemite portion of the tails that can be used in economic studies of the installation of a dedicated tailings processing circuit.

 

2. Calamine processing test work: continue process development test work to improve recovery, including the evaluation of collectors for improved recovery of hemimorphite, and consider options that may help to improve recovery from calamine mineralization such as:

 

o Separate processing of calamine and willemite mineralization.

 

o A coarser primary grind for calamine mineralization and evaluation of the effect of a coarser primary grind on the proportion of fines in the flotation feed and zinc (and zinc mineral) deportment to fines.

 

o Separate processing of the fines fraction to recover hemimorphite in a purpose-built fines processing circuit, which could also be used for processing historical calamine tailings.

 

3. Consider developing a combined strategy for processing historical tailings and calamine ore, since the two feeds, or portions of the feeds (e.g., calamine fines) may require similar equipment for processing; this strategy could then help with test work planning, production, and financial planning.

 

23.4 Environment & Social

 

1. Although it is not a requirement in the Operation Licences, SLR recommends considering the implementation of a monitoring program for flora and fauna for the Vazante Operation.

 

2. The Golder closure report (No. RT-006_169-525-2593_03-J 75, dated January 2018) recommends that a more detailed assessment be made of the impact of ore processing on the potential for release of sulphates from the tailings at the Pilha Garrote DSTSF.

 

3. The placement and compaction of the filtered and cyclone tailings during the wet season should be considered.

 

4. Dust generation from the Pilha Garrote DSTSF during the dry season must be considered.

 

5. The water balance for the Aroeira TSF must be reviewed through additional water balance modelling to determine the impact of use as a water management facility, increased mine dewatering and surface runoff from the Pilha Garrote DSTSF. Different climate scenarios should be simulated to account for years with annual precipitation below and above the statistical average (i.e. dry and wet years). The water balance modelling should be used to investigate changes in water availability for ore processing and changes in effluent discharge rates to the Santa Catarina River.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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23.5 Cost and Economic Analysis

 

1. Continuously monitor costs and exchange rates and lock in costs as soon as possible to eliminate economic uncertainty.

 

2. Continue efforts towards improving efficiencies and approaches to mining and development operations as opportunities arise in these areas.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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24.0 References

 

Almeida, F.F.M., 1977, O Cráton São Francisco: Brasil; Brazilian Journal of Geology (formerly Revisa Brasileira de Geosciéncias), no. 7, p. 349-364.

 

Alvarenga, C.J.S., Oliveira, G.D., Viera, L.C., Santon, R., Baptista, M.C., and Dnatas, El. L., 2019, Carbonate Chemostratigraphy of the Vazante Group, Brazil: A Probable Tonian Age: Elsevier Precambrian Research, 331, p. 1-14.

 

Amec Foster Wheeler Peru S.A., 2017, Vazante Polymetallic Operations, Minas Gerais State, Brazil, NI 43-101 Technical Report on Operations: prepared for V.M. Holding S.A., p. 332.

 

Appold, M.S., and Monteiro, L.V.S., 2009, Numerical Modelling of Hydrothermal Zinc Silicate and Sulphide Mineralization in the Vazante Deposit, Brazil: Geofluids, 9, p. 96-115.

 

Babinski, M., 2005, A Idade do Supergroupo São Francisco: Revisão e Implicaçãos nas Glaciações Neoproterozóicas: SBG, Simpósio sobre o Cráton do São Francisco, v. 3, p. 135-138.

 

Beurlen, H., 1974, Sobre A Origem Dingenenetico-Sedimantar De Alguns Corpos Mineralizados Em Chumbo, Zonce E Fluorita No Groupo Bambuí E Dispersão Geoquí Mica Prima Ria Dos Elementos ineralizantes: Proceedings of the XXVII Congresso Brasileiro de Geologia, Sociadade Brasileira de Geologia, SBG-RS, v. 6, p 49-60.

 

Brandt Meoi Ambiente, 2011, Unidade Vazante, Expansão da Area de Lavra da Mina Subterrânea de Willemita – Extremo Norte (Antiga Masa), prepared for Votorantim Metais Zinco S/A, February 2011.

 

Brugger, J., McPhail, D.C., Wallace, M., and Waters, J., 2003, Formation of Willemite in Hydrothermal Environments: Economic Geology v. 98, p 819-835.

 

Canadian Institute of Mining, Metallurgy and Petroleum (CIM), 2014, CIM Definition Standards for Mineral Resources and Mineral Reserves, adopted by the CIM Council on May 10, 2014.

 

Dardenne, M., A., 1978, Sintese Sobre a Estratigrafia do Groupo Bambuí no Brasil Central: in Congresso Brasileiro de Geologia, p. 597-610.

 

Dardenne, M.A., 1979, Les Minéralisations De Plomb, Zinc, Fluor Du Proterozoique Supérieur Dans Le Brésil Central: Ph. D. thesis, University of Paris VI, p. 251.

 

Dardenne, M.A., 1998, Freitas-Silva, F.H., Nogueira, G.M.S., and Campos, J.E.G., 1998, Evolução Tectono-Sedimentar Do Grupo Vazante No Contexto Da Faixa De Dobramentos Brasilia: Congresso Brasileiro de Geologia, 40, SBG, Belo Horizonte, Anais, p. 26.

 

 

 

Nexa Resources S.A. | Vazante Polymetallic Operations, SLR Project No: 233.03245.R0000

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Dardenne, M. A., 2000, The Brasilia Fold Belt: in Cordani, U.G., Milani, E.J., Thomaz-Filho, A., and Campos, D. A., (Eds.), Tectonic Evolution of South America, 31st International Geological Congress, Rio de Janeiro, p. 231-263.

 

Diagonal and Instituto Votoratim, 2015, Caracterização Socioeconômica, Votorantim Metais – Unidade Vazante, December 2015.

 

dos Santos, A., Imaculada de Paula, C., Junior, L., Santos, M., Peixoto, P., Pedrosa, S., and de Quadros, T., 2016, Departamento Nacional de Produção Mineral Manual Téchnico de Imissão de Posse, Elaboração CGTIG/DGTM, Versão 6: Document published by the Ministéro de Minas e Energia, p. 60.

 

Ecolab, 2018, Unidade Vazante, Relatório de Controle Ambiental e Plano de Controle Ambiental, Projecto Amplição da Capacidade da Usina de Concentração (USICON), prepared for Nexa Resources, November 2018.

 

Engler, A., 2009, The Geology of South America: Geology Vol. IV, p. 374-405.

 

Ferreira, G.S., 2020, Letter expressing an opinion on section 4 content in this technical report, prepared for Nexa Resources S.A., 17 July 2020.

 

Geoconsultoria, 2000, Nova Barragem de Rejeitos, Obras Iniciais, Projeto Executivo, Relatório Técnico CM01-RT-04 Rev. 0, July 2000.

 

Geoconsultoria, 2016a, Depósito de Estéril Bocaina, Projeto Executivo, Relatório Técnico CM63-RT-01 Rev. 0, January 2016.

 

Geoconsultoria, 2016b, Depósito de Estéril Extremo Norte, Projeto Executivo, Relatório Técnico CM63-RT-02 Rev. 0, January 2016.

 

Geoconsultoria, 2016c, Depósito de Estéril Sucuri, Projeto Executivo, Relatório Técnico CM63-RT-03 Rev. 0, January 2016.

 

Geoconsultoria, 2017: Análise de Risco - Barragem Aroeira, Relatório Técnico CM39-RT-01 Rev. 4, October 2017.

 

Geoconsultoria, 2019, Barragem Aroeira, Relatório da Auditoria de Segurança – FEAM, Relatório de Inspeção de Segurança Regular (RISR) – ANM, Relatório Técnico CM18-RT57 Rev.0, August 30, 2019.

 

Geoconsultoria, 2020, Barragem Aroeira, Relatório da Auditoria de Segurança – FEAM, Relatório de Inspeção de Segurança Regular (RISR) – ANM, 2o Semestre 2020, Relatório Técnico CM18-RT60 Rev.0, August 28, 2020.

 

 

 

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Golder Associates, 2018, Projeto de Detalhamento das Ações de Descomissionamento da Unidade Vazante, Volumes I and II, Relatório Consolidado (Mine Closure Plan), Report RT-006_169-525-2593_03-J prepared for V.M. Holding S.A., January 2018.

 

Guimarães, D., 1962, Genese do Miniero de Zinco de Vazante, Minas Gerais: Sociedad Intercambeo Cultral e Estudios Geologia, Ouro Preto, 2, p. 101-147.

 

Hidrogeo Assessoria Ambiental Ltda, 2016, Classificação dos Rejeitos de Flotação da Unidad de Vazante/MG (Classification of Tailings from Flotation of Vazante), Report RT-01-01-GE-17-16-F prepared for Votorantim Metais, September 2016.

 

Hitzman, M.W., and Beaty, D.W., 1996, The Irish Zn-Pb-(Ba) Orefield: in Sangster, D.F., ed., Carbonate-hosted Lead-Zinc Deposits: Society of Economic Geologists Special Publication 4, p. 112-143.

 

Hitzman, M.W., Reynolds, N.A., Sandster, D.F., Aleen, C.R., and Carman, C.E., 2003, Classification, Genesis, and Exploration Guides for Non-sulphide Zinc Deposits: Economic Geology, v. 98, p. 685-714.

 

Lyer, S.S., 1984, A Discussion on the Lead Isotope Geochemistry of Galenas from the Bambuí Group, Minas Gerais – Brasil: Mineralium Deposita, April 1984, v. 19, Issue 2, p. 132-137.

 

Lyer, S.S., Hoefs, J., and Krouse, H.R., 1992, Sulfur and Lead Isotope Geochemistry of Galenas from Bambuí Group, Minas Gerais – Brasil: Implications on Ore Genesis: Econ. Geol. v. 87, p. 437-443.

 

McGladry, A.J. 2014, The Integration of Physical Rock Properties, Mineralogy, and Geochemistry for the Exploration of Large Hypogene Zinc Silicate Deposits: a Case Study of the Vazante Zinc Deposits, Minas Gerais, Brazil: M. Sc. Thesis, Queens University, Canada, p. 177.

 

Monteiro, L.V.S., 2002, Modelamento Metalgenético dos Depósitos de Zinco de Vazante, Fagundes e Amroósia, Associados ao Group Vazante, Minas Gerais: Tese de Doutorado (Ph.D. Dissertation), Universidade de São Paulo, São Paulo.

 

Monteiro, L.V.S, Bettencourt, J.S., Spiro, B., Graca, R., and Oliveira, T.F., 1999, The Vazante Zinc Mine, Minas Gerais, Brazil: Constraints on Willemitic Mineralization and Fluid Evolution: Exploration and Mining Journal, v. 8, p. 21-42.

 

Monteiro, L.V.S., Bettencourt, J.S., Juliani, C., and Oliveira, T.F., 2006, Geology, Petrography, and Mineral Chemistry of the Vazante Non-Sulphide and Anbrósia and Fagundes Sulphide-Rich Carbonate-Hosted Zn-(Pb) Deposits, Minas Gerais, Brazil: Ore Geology Reviews, v. 28(2), p. 201-234.

 

Monteiro, L.V.S., Bettencourt, J.S., Juliani, C., and Oliveira, T.F., 2007, Non-Sulphide and Sulphide-Rich Zinc Mineralizations in Vazante, Ambrosia and Fagundes Deposits, Minas Gerais, Brazil: Mass Balance and Stable Isotope Characteristics of the Hydrothermal Alterations: Gondwana Res. 11, p. 362-381.

 

Nexa Resources S.A., 2017, Plano de Desenvolvimento Local, Unidade Vazante (Community Relations Plan), December 2017.

 

 

 

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Nexa Resources S.A., 2018, Alternativa Tecnológica para Tratamento de Calamina, Relatόrio Técnico, December 2018.

 

Nexa Resources S.A., 2019, Nexa Resources Announces Its 2018 Year End Mineral Reserves and Mineral Resources: News Release available from the Nexa filings on the SEDAR website at www.SEDAR.com, p. 8.

 

Nexa Resources S.A., 2019, Corporate Policies.

 

Nexa Resources S.A., 2020a, Atendimento a Condicionante No. 1, Processo COPAM No. 104/1988/056/2014 – LO No. 005/2016 submitted to SUPRAM Noroeste de Minas, dated March 30, 2020.

 

Nexa Resources S.A., 2020b, Atendimento a Condicionante No. 1, Processo COPAM No. 104/1988/063/2018 – LO No. 051/2019 submitted to SUPRAM Noroeste de Minas, dated October 22, 2020.

 

Nexa Resources S.A., 2020c, Annual Report 2019 (March 2020).

 

Nexa Resources S.A., 2020d, Information Relating to Mineral Properties as of March 20, 2020: Document available in the Nexa filings on the SEDAR website at www.SEDAR.com, 95 p.

 

Olivio, G. R., Monteiro, L.V.S., Baia, F., Slezak, P., Carvalho, I., Fernandes, N.A., Oliveria, G.D., Neto, B.B., McGladrey, A., Silva, A.M., Moura, M.A. and Layton-Matthews, D., 2018, The Proterozoic Vazante Hypogene Zinc Silicate District, Minas Gerais, Brazil: A Review of the Ore System Applied to Mineral Exploration: Minerals, v. 8-22, p. 1-17.

 

Pinho, J.M.M., 1990, Evolução Tectônica Da Mineralizacao De Zinco De Vazante, Brasília: M.Sc. thesis Universidade de Brasília, Brasília.

 

Slezak, P.R., Olivo, G.R., Olivera, G.D., and Dardenne, M.A., 2013, Geology, Mineralogy, and Geochemistry of the Vazante Northern Extension Zinc Silicate Deposit, Minas Gerais, Brazil: Ore Geology Reviews, v. 56, p. 234-257.

 

SGS GEOSOL, 2019, Estudo Piloto de Flotação com Rejeito de Willemita da Barragem de Vazante (MG), prepared for Nexa Resources (November, 2019).

 

Tassinari, C. C. G. Cordani, U. G., Nutman, A.P., Van Schmus, W.R., Bettencourt, J.S., and Taylor, P.N., 2010, Geochronological Systematics on Basement Rocks from the Rio Negro-Juruena Province (Amazon Craton) and Tectonic Implications: International Geology Review, VI 38, Issue 2.

 

US Securities and Exchange Commission, 2018: Regulation S-K, Subpart 229.1300, Item 1300 Disclosure by Registrants Engaged in Mining Operations and Item 601 (b)(96) Technical Report Summary.

 

Votorantim, 2020, Legal Opinion – Ownership and/or Possesion Rights Related to Aripuanã and Vazante Sites, prepared for Nexa Recursos Minerais S.A., 28 April 2020

 

 

 

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25.0 Reliance on Information Provided by the Registrant

 

This Technical Report Summary has been prepared by SLR Consulting Ltd (SLR) for Nexa. The information, conclusions, opinions, and estimates contained herein are based on:

 

· Information available to SLR at the time of preparation of this Technical Report Summary,

 

· Assumptions, conditions, and qualifications as set forth in this Technical Report Summary, and

 

· Data, reports, and other information supplied by Nexa and other third party sources.

 

For the purpose of this Technical Report Summary, and in particular the completion of Section 3, SLR has relied on ownership information provided by Nexa in its internal legal opinion dated April 28, 2020 (Votorantim, 2020) and an internal legal opinion by Guilherme Simões Ferreira, Legal Department - Nexa Resources, dated 17 July 2020 (Ferreira, 2020). SLR has not researched property title or mineral rights for Vazante and expresses no opinion as to the ownership status of the property.

 

SLR has relied on Nexa for guidance on applicable taxes, royalties, and other government levies or interests, applicable to revenue or income from the Vazante Operation.

 

Except for the purposes legislated under provincial securities laws, any use of this Technical Report Summary by any third party is at that party’s sole risk.

 

 

 

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26.0 Date and Signature Page

 

This report titled “Technical Report Summary on the Vazante Polymetallic Operations, Minas Gerais, Brazil” dated February 15, 2021, and effective December 31, 2020, was prepared and signed by:

 

SLR Consulting (Canada) Ltd. (Signed) SLR Consulting (Canada) Ltd.

 

Dated at Toronto, ON

February 15, 2021

 

 

 

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Exhibit 15.9