Peñasquito Operations
Mexico
Technical Report Summary
Report current as of:
December 31, 2021
Qualified Person:
Mr. Donald Doe, RM SME.
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
| | |
NOTE REGARDING FORWARD-LOOKING INFORMATION |
This Technical Report Summary contains forward-looking statements within the meaning of the U.S. Securities Act of 1933 and the U.S. Securities Exchange Act of 1934 (and the equivalent under Canadian securities laws), that are intended to be covered by the safe harbor created by such sections. Such forward-looking statements include, without limitation, statements regarding Newmont’s expectation for its mines and any related development or expansions, including estimated cash flows, production, revenue, EBITDA, costs, taxes, capital, rates of return, mine plans, material mined and processed, recoveries and grade, future mineralization, future adjustments and sensitivities and other statements that are not historical facts.
Forward-looking statements address activities, events, or developments that Newmont expects or anticipates will or may occur in the future and are based on current expectations and assumptions. Although Newmont’s management believes that its expectations are based on reasonable assumptions, it can give no assurance that these expectations will prove correct. Such assumptions, include, but are not limited to: (i) there being no significant change to current geotechnical, metallurgical, hydrological and other physical conditions; (ii) permitting, development, operations and expansion of operations and projects being consistent with current expectations and mine plans, including, without limitation, receipt of export approvals; (iii) political developments in any jurisdiction in which Newmont operates being consistent with its current expectations; (iv) certain exchange rate assumptions being approximately consistent with current levels; (v) certain price assumptions for gold, copper, silver, zinc, lead and oil; (vi) prices for key supplies being approximately consistent with current levels; and (vii) other planning assumptions.
Important factors that could cause actual results to differ materially from those in the forward-looking statements include, among others, risks that estimates of mineral reserves and mineral resources are uncertain and the volume and grade of ore actually recovered may vary from our estimates, risks relating to fluctuations in metal prices; risks due to the inherently hazardous nature of mining-related activities; risks related to the jurisdictions in which we operate, uncertainties due to health and safety considerations, including COVID-19, uncertainties related to environmental considerations, including, without limitation, climate change, uncertainties relating to obtaining approvals and permits, including renewals, from governmental regulatory authorities; and uncertainties related to changes in law; as well as those factors discussed in Newmont’s filings with the U.S. Securities and Exchange Commission, including Newmont’s latest Annual Report on Form 10-K for the period ended December 31, 2021, which is available on newmont.com.
Newmont does not undertake any obligation to release publicly revisions to any “forward-looking statement,” including, without limitation, outlook, to reflect events or circumstances after the date of this document, or to reflect the occurrence of unanticipated events, except as may be required under applicable securities laws. Investors should not assume that any lack of update to a previously issued “forward-looking statement” constitutes a reaffirmation of that statement. Continued reliance on “forward-looking statements” is at investors’ own risk.
| | | | | | | | |
Date: February 2022 | | Page a |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
| | | | | | | | |
| | |
Date: February, 2022 | | Page i |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
| | | | | | | | |
| | |
Date: February, 2022 | | Page ii |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
| | | | | | | | |
| | |
Date: February, 2022 | | Page iii |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
| | | | | | | | |
| | |
Date: February, 2022 | | Page iv |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
| | | | | | | | |
| | |
Date: February, 2022 | | Page v |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
| | | | | | | | |
| | |
Date: February, 2022 | | Page vi |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
| | | | | | | | |
| | |
Date: February, 2022 | | Page vii |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
| | | | | | | | |
| | |
Date: February, 2022 | | Page viii |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
1.0 SUMMARY
1.1 Introduction
This technical report summary (the Report) was prepared for Newmont Corporation (Newmont) on the Peñasquito Operations (Peñasquito Operations or the Project) located in Zacatecas State, Mexico.
The operating entity is an indirectly wholly-owned Newmont subsidiary, Minera Peñasquito S.A. de C.V. (Minera Peñasquito). For the purpose of this Report, “Newmont” is used interchangeably to refer to the parent and the fully-owned subsidiary companies in Mexico.
1.2 Terms of Reference
The Report was prepared to be attached as an exhibit to support mineral property disclosure, including mineral resource and mineral reserve estimates, for the Peñasquito Operations in Newmont’s Form 10-K for the year ending December 31, 2021.
Mineral resources and mineral reserves are reported for the Peñasco and Chile Colorado deposits. Mineral reserves are also estimated for material in stockpiles.
Open pit mining commenced in 2010, and commercial production was reached during 2011. The open pit feeds a sulfide concentrator (mill).
Unless otherwise indicated, all financial values are reported in United States dollars (US$). Unless otherwise indicated, the metric system is used in this report for mineral resources and mineral reserves and associated financials. Mineral resources and mineral reserves are reported using the definitions in Regulation S–K 1300 (SK1300), under Item 1300. The Report uses US English. The Report contains forward-looking information; refer to the note regarding forward-looking information at the front of the Report.
1.3 Property Setting
The Peñasquito Operations are situated in the western half of the Concepción Del Oro district in the northeast corner of Zacatecas State, Mexico, approximately 200 km northeast of the city of Zacatecas. There are two main access routes, the first via a turnoff from Highway 54 onto the State La Pardita road, then onto the Mazapil to Cedros State road. The mine entrance is approximately 10 km after turning northeast onto the Cedros access road. The second is via the Salaverna by-pass road from Highway 54 approximately 25 km south of Concepcion Del Oro. The Salaverna by-pass is a purpose-built gravel road that eliminates steep switchback sections of cobblestone road just west of Concepción Del Oro and passes the town of Mazapil. From Mazapil, this is a well-maintained 12 km gravel road that accesses the mine main gate. There is a private airport on site and commercial airports in the cities of Saltillo, Zacatecas and Monterrey.
The climate is generally dry with precipitation being limited for the most part to a rainy season in the months of June and July. Mining operations are conducted year-round.
The terrain is generally flat, with some rolling hills. The prevailing elevation is approximately 1,900 m above sea level. Vegetation is principally scrub, with cactus and coarse grasses.
| | | | | | | | |
Date: February 2022 | | Page 1-1 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
1.4 Ownership
The Peñasquito Operations is indirectly 100% held by Newmont through its subsidiary Minera Peñasquito.
1.5 Mineral Tenure, Surface Rights, Water Rights, Royalties and Agreements
Newmont currently holds 77 mining concessions (approximately 82,632 ha). The mining operations are within the Las Peñas, Alfa, La Peña and El Peñasquito concessions. As per Mexican requirements for grant of tenure, the concessions comprising the Project were surveyed by a licensed surveyor. Duty payments for the concessions have been made as required.
Surface rights in the vicinity of the Chile Colorado and Peñasco open pits are held by four ejidos: Ejido Cedros, Ejido Mazapil, Ejido El Vergel and Ejido Cerro Gordo. Newmont has entered into agreements with a number of ejidos in relation to surface rights, either for mining or exploration activities. Under current agreements with the ejidos, payments are made to the ejidos on an annual basis, in addition to certain upfront payments that have already been made. All temporary occupancy (such as land use) agreements are filed with the Public Agrarian Registry and the Public Mining Registry. All required power line and road easements have been granted.
Based on completed applications, a 4.6 Mm3 concession was obtained in August 2006 and an additional water concession of 9.1 Mm3 per year was received in early 2008. A concession title to pump 4.837 Mm3 was received in November 2008. A concession title to pump an additional 0.450 Mm3 was obtained in April 2009, and an additional 16.87 Mm3 concession title was obtained in July 2009.
On July 24, 2007, Goldcorp Inc. (a predecessor Newmont company) and Wheaton Precious Metals (Wheaton) entered into a transaction where Wheaton acquired 25% of the silver produced over the life-of mine (LOM) from the Peñasquito Operations for an upfront cash payment of US$485 million. Under this transaction, Wheaton pays Newmont a per-ounce cash payment of the lesser of US$3.90 and the prevailing market price (subject to an inflationary adjustment that commenced in 2011), for silver delivered under the contract.
A 2% net smelter return (NSR) royalty is payable to Royal Gold on production from the Chile Colorado and Peñasco deposits. The Mexican Government levies a 7.5% mining royalty that is imposed on earnings before interest, taxes, depreciation, and amortization. There is also a 0.5% environmental erosion fee payable on precious metals, based on gross revenues.
1.6 Geology and Mineralization
The deposits within the Peñasquito Operations are considered to be examples of breccia pipe deposits developed as a result of intrusion-related hydrothermal activity.
The regional geology of the project area is dominated by Mesozoic sedimentary rocks, which are intruded by Tertiary stocks of intermediate composition (granodiorite and quartz monzonite) and overlain by Tertiary terrestrial sediments and Quaternary alluvium.
| | | | | | | | |
Date: February 2022 | | Page 1-2 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Peñasco and Brecha Azul are funnel-shaped breccia pipes, which flare upward, and are filled with brecciated sedimentary and intrusive rocks, cut by intrusive dikes. Polymetallic mineralization is hosted by the diatreme breccias, intrusive dikes, and surrounding siltstone and sandstone units of the Cretaceous Caracol Formation.
The diatreme and sediments contain, and are surrounded by, disseminated, veinlet and vein-hosted sulfides and sulfosalts containing base metals, silver, and gold. Mineralization is breccia or dike hosted, mantos, or associated with skarns. Mineralization consists of disseminations, veinlets and veins of various combinations of medium to coarse-grained pyrite, sphalerite, galena, and argentite (Ag2S). Sulfosalts of various compositions are also abundant in places, including bournonite (PbCuSbS3), jamesonite (PbSb2S4), tetrahedrite, polybasite ((Ag,Cu)16(Sb,As)2S11), and pyrargyrite (Ag3SbS3). Stibnite (Sb2S3), rare hessite (AgTe), chalcopyrite, and molybdenite have also been identified. Telluride minerals are the main gold-bearing phase, with electrum and native gold also identified.
1.7 History
Prior to Newmont obtaining 100% interest in the Peñasquito Operations, the following companies either held an interest or performed exploration activities: Minera Kennecott SA de CV (Kennecott), Western Copper Holdings Ltd. (Western Copper), Western Silver Corporation (Western Silver), Mauricio Hochschild & Cia Ltda. (Hochschild), Glamis Gold Corporation (Glamis) and Goldcorp Inc. (Goldcorp). Work undertaken included reconnaissance geological inspections, regional-scale geochemical and geophysical surveys (including gravity, controlled source audio frequency magnetollurics, reconnaissance induced polarization, scaler induced polarization, airborne radiometrics and magnetics and ground magnetics), rotary air blast (RAB), reverse circulation (RC) and core drilling. A pre-feasibility study was undertaken in 2004, a feasibility study in 2005 and a feasibility study update in 2006. Mine construction commenced in 2007.
Newmont acquired Goldcorp in 2019, and became the Project operator. Newmont has continued mining operations, and has conducted additional metallurgical testwork, internal mining studies, and core and RC drill programs in support of mine area and regional exploration activities.
1.8 Drilling and Sampling
1.8.1 Drilling
Drilling to December 31, 2021 comprises 1,670 core holes (867,075 m), 52 RC holes with core tails (26,332 m) and 270 RC holes (42,247 m) for a total of 1,992 drill holes (935,638 m). Drilling focused on the exploration and delineation of Chile Colorado, Brecha Azul Zone and Peñasco.
Drilling that supports mineral resource and mineral reserve estimation consists of core and RC drill holes, and totals 1,647 holes for 816,195 m.
Standardized logging procedures and software are used to record geological and geotechnical information. The level of detail collected varied by drill program and operator, but generally collected lithology, alteration, mineralization, structural features, oxidation description, and vein
| | | | | | | | |
Date: February 2022 | | Page 1-3 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
types. Core recovery is good, averaging about 97%. Collar location methods included chain-and-compass, or digital global positioning system (DGPS) instruments. Downhole survey instrumentation included single shot and gyroscopic tools.
1.8.2 Hydrogeology
A combination of historical and current hydrological data, together with operating experience, govern the pit dewatering plan. There are currently two groundwater models for pit dewatering that cover the two open pits, and a regional-scale aquifer model.
Pit dewatering is undertaken using vertical, in-pit dewatering wells. Mining operations staff perform water level monitoring on observation and pumping wells.
Monitoring wells are used to track potential environmental non-compliance in the vicinity of the tailings storage facility (TSF) and heap leach pad facilities; to date, no significant issues have been identified by the monitoring programs.
1.8.3 Geotechnical
A combination of historical and current geotechnical data, together with mining experience, are used to established pit slope designs and procedures that all benches must follow. The geotechnical model for the Peñasquito Operations was defined by geotechnical drilling and logging, laboratory testwork, rock mass classification, structural analysis and stability modeling. Analytical methods are used to evaluate structural behavior of the rock mass. Third-party consultants were retained to provide the recommended pit slope guidelines.
A geotechnical events register is maintained, and incidences are logged. There is also a record of the zones of instability zones in each pit, with information such as location, key structural data, lithologies, and event type noted.
1.8.4 Sampling and Assay
RC and core drill holes were sampled at intervals of 2 m.
Bulk density values were collected primarily using the water immersion method.
Independent laboratories used for sample preparation and analysis included ALS Chemex, and Bondar Clegg (absorbed into ALS Chemex in 2001). At the time the early work was performed ALS Chemex was ISO-9000 accredited for analysis; the laboratory is currently ISO-17025 certified. Independent check laboratories included Acme Laboratories in Vancouver, which at the time held ISO-9000 accreditation, and more recently, SGS Mexico (SGS), which holds ISO/IEC 17025:2005 certification. The on-site mine laboratory is not certified and is not independent of Newmont.
Various sample preparation crushing and pulverizing protocols were used since the late 1900s, depending on the drill campaign. ALS Chemex crushed to either ≥70% or 75% passing 10 mesh (2.0 mm) and pulverized to either ≥85% or ≥95% passing 200 mesh (75 µm). The onsite laboratory crushed to ≥70% passing 10 mesh and pulverized to ≥85% passing 200 mesh (75 µm). Analytical methods also varied by campaign. Gold analyses consisted of fire assays with either atomic absorption (AA) or inductively-coupled plasma (ICP) emissions spectrometer (ES) finishes. Overlimits were assayed using fire assay with a gravimetric finish. Silver assays were
| | | | | | | | |
Date: February 2022 | | Page 1-4 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
performed using ICP-ES or ICP atomic emission spectroscopy (AES). Overlimits were assayed using fire assay with a gravimetric finish. Zinc and lead assays were reported from either ICP-AES or ICP mass spectrometer (MS) methods.
1.8.5 Quality Assurance and Quality Control
A quality assurance and quality control (QA/QC) program was in place from 2006 onward. Goldcorp, Newmont Goldcorp, and Newmont maintained a quality assurance and quality control (QA/QC) program for the Peñasquito Operations. This included regular submissions of blank, duplicate and standard reference materials (standards) in samples sent for analysis from both exploration and mine geology.
Results were and are regularly monitored. The QA/QC programs adequately address issues of precision, accuracy and contamination.
1.9 Data Verification
Newmont personnel regularly visit the laboratories that process Newmont samples to inspect sample preparation and analytical procedures.
The database that supports mineral resource and mineral reserve estimates is checked using electronic data scripts and triggers. Newmont also conducted a number of internal data verification programs since obtaining its Project interest. Newmont conducts internal audits, termed Reserve and Resource Review (3R) audits, of all its operations. The most recent Peñasquito Operations 3R audits were conducted in 2019 and 2021. The 2021 3R audit found that the Peñasquito Operations were generally adhering to Newmont’s internal standards and guidelines with respect to the estimation of mineral resources and mineral reserves.
Data verification was performed by external consultants in support of mine development and operations. These external reviews were also undertaken in support of acquisitions, support of feasibility-level studies, and in support of technical reports, producing independent assessments of the database quality.
The QP receives and reviews monthly reconciliation reports from the mine site. These reports include the industry standard reconciliation factors for tonnage, grade and metal. Through the review of these reconciliation factors the QP is able to ascertain the quality and accuracy of the data and its suitability for use in the assumptions underlying the mineral resource and mineral reserve estimates.
1.10 Metallurgical Testwork
Metallurgical testwork was conducted by a number of laboratories prior to and during early operations. Current testwork is being performed at Newmont’s internal Malozemoff Technical Facility and by independent laboratories.
Metallurgical testwork included: mineralogy; open and closed-circuit flotation; lead–copper separation flotation; pyrite flotation; bottle and column cyanide leaching; flotation kinetics and cell design parameters, flowsheet definition, and leach response with regrind size, slurry density, leaching time, reagent consumption values, and organic carbon effects; gravity-recoverable gold; hardness characterization (SMC, breakage parameter, Bond ball mill work index, drop
| | | | | | | | |
Date: February 2022 | | Page 1-5 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
weight index, rod work index, unconfined compressive strength, semi-autogenous grind (SAG) power index); and batch and pilot plant tests. These test programs were sufficient to establish the optimal processing routes for the oxide and sulfide ores, performed on mineralization that was typical of the deposits. The results obtained supported estimation of recovery factors for the various ore types.
Since the early start-up of operations, metallurgical testing was performed on a daily basis for all ores that have been feed to the mill. These daily tests have been aimed to capture the expected performance of the ore in the sulfide plant to determine in advance any change in the reagent scheme or in the impurity levels into the final concentrates. Historically, this resulted in identification of a number of different ore types. Current understanding of ore characterization and variability has simplified forecast metallurgical recovery classification to sediment and diatreme ores and the relative organic carbon content.
Samples selected for metallurgical testing during feasibility and development studies were representative of the various types and styles of mineralization within the deposit. Samples were selected from a range of locations within the deposit zones. Sufficient samples were taken so that tests were performed on sufficient sample mass.
The mineralogical complexity of the Peñasquito ores makes the development of recovery models difficult as eight elements (gold, silver, lead, zinc, copper, iron, arsenic, and antimony) are tracked through the process. Recovery models need to be sufficiently robust to allow for changes in mineralogy and plant operations, while providing reasonable predictions of concentrate quality and tonnage. LOM recovery forecasts the sulfide plant are 69% for gold, 87% for silver, 73% for lead, and 81% for zinc.
Sulfosalts can carry varying amounts of deleterious elements such as arsenic, antimony, copper and mercury. At the date of this Report, the processing plant, in particular the flotation portion of the circuit, does not separate the copper-bearing minerals from the lead minerals, so when present the sulfosalts report (primarily) to the lead concentrate. The future impact of the deleterious elements is thus highly dependent on the lead–copper ratio in ores. There is no direct effect of deleterious elements on the recovery of precious and base metals. The marketing contracts are structured to allow for small percentages of these deleterious elements to be incorporated into the final product, with any exceedances then incurring nominal penalties.
One small area of the mine was defined as containing above-average mercury grades. Due to its limited size, blending should be sufficient to minimize the impact of mercury from this area on concentrate quality.
Organic carbon has also been recognized as a deleterious element affecting the recovery of gold and the operational cost in the process plant. The carbon pre-flotation process was built to allow for removal of liberated organic carbon ahead of lead and zinc flotation and the pyrite leach plant, so that those process steps could operate in a similar fashion to operation with low-carbon ores
1.11 Mineral Resource Estimation
1.11.1 Estimation Methodology
The database supporting resource estimation contains core drilling information from numerous drilling campaigns beginning in the 1990s through to the database close-out date of 10 June,
| | | | | | | | |
Date: February 2022 | | Page 1-6 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
2021. Geological interpretations were compiled using Leapfrog software. MineSight was used for compositing and grade interpolation. Exploratory data analysis included statistical reviews and contact analysis to determine estimation domain boundaries.
Models constructed included lithology, alteration, structure, oxidation, grade shells, north–south domains, fault domains, and organic carbon.
Density was tabulated by a combination of lithology, alteration and zone. Density values may be decreased based on the presence of oxides and/or faulting within the block being estimated.
Grade caps were applied by domain and could vary. Depending on domain, gold, silver, lead, zinc, copper, arsenic, antimony and sulfur grades could be capped. No capping was applied to organic carbon or iron values. An isotropic search distance that ranged from about 50–100 m was used to constrain the extrapolation of high grades (outlier restriction) for most elements and domains. Compositing was done on 5 m intervals. Spatial variability of the grades was examined using correlograms and/or variograms.
Ordinary kriging was used to interpolate blocks, using two passes for all elements other than iron. A range of inputs were used by domain. Iron was estimated using inverse distance weighting to the second power.
Validation used Newmont-standard methods, including a combination of visual checks, swath plots, global statistical bias checks against input data, alternate estimation methods and reconciliation with historical mine/plant performance. The validation procedures indicated that the geology and resource models used are acceptable to support the mineral resource estimation.
Mineral resource classification was undertaken based primarily on drill spacing and number of drill holes used in the estimate. Mineral resources were classified as measured, indicated, and inferred. A quantitative assessment of geological risk was undertaken using Newmont-standard methods and applied on a block by block basis. Primary risks to resource quality include quantity and spacings of drill data, geological knowledge, geological interpretation and grade estimates. All identified risks are within acceptable tolerances with associated management plans.
Mineral resources considered amenable to open pit mining methods are reported within a mine design. Commodity prices used in resource estimation are based on long-term analyst and bank forecasts, supplemented with research by Newmont’s internal specialists. The estimated timeframe used for the price forecasts is the 10-year LOM that supports the mineral reserve estimates.
1.11.2 Mineral Resource Statement
Mineral resources are reported using the mineral resource definitions set out in SK1300, and are reported in situ. Mineral resources are reported exclusive of those mineral resources converted to mineral reserves. Mineral resources that are not mineral reserves do not have demonstrated economic viability.
The mineral resource estimates for the Peñasquito Operations are provided as follows:
•Gold: Table 1-1 (measured and indicated); Table 1-2 (inferred);
•Silver: Table 1-3 (measured and indicated); Table 1-4 (inferred);
| | | | | | | | |
Date: February 2022 | | Page 1-7 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
•Lead: Table 1-5 (measured and indicated); Table 1-6 (inferred);
•Zinc: Table 1-7 (measured and indicated); Table 1-8 (inferred).
Table 1-1: Measured and Indicated Mineral Resource Statement (Gold)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Measured Mineral Resources | Indicated Mineral Resources | Measured and Indicated Mineral Resources |
Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) |
Peñasquito | 31,400 | 0.27 | 280 | 176,600 | 0.27 | 1,500 | 208,000 | 0.27 | 1,780 |
Table 1-2: Inferred Mineral Resource Statement (Gold)
| | | | | | | | | | | |
Area | Inferred Mineral Resources |
Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) |
Peñasquito | 89,800 | 0.4 | 1,160 |
Table 1-3: Measured and Indicated Mineral Resource Statement (Silver)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Measured Mineral Resources | Indicated Mineral Resources | Measured and Indicated Mineral Resources |
Tonnage (x 1,000 t) | Grade (g/t Ag) | Cont. Silver (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Ag) | Cont. Silver (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Ag) | Cont. Silver (x 1,000 oz) |
Peñasquito | 31,400 | 25.71 | 25,990 | 176,600 | 26.36 | 149,620 | 208,000 | 26.26 | 175,610 |
Table 1-4: Inferred Mineral Resource Statement (Silver)
| | | | | | | | | | | |
Area | Inferred Mineral Resources |
Tonnage (x 1,000 t) | Grade (g/t Ag) | Cont. Silver (x 1,000 oz) |
Peñasquito | 89,800 | 28.0 | 80,840 |
Table 1-5: Measured and Indicated Mineral Resource Statement (Lead)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Measured Mineral Resources | Indicated Mineral Resources | Measured and Indicated Mineral Resources |
Tonnage (x 1,000 t) | Grade (% Pb) | Contained Lead (M lbs) | Tonnage (x 1,000 t) | Grade (% Pb) | Contained Lead (M lbs) | Tonnage (x 1,000 t) | Grade (% Pb) | Contained Lead (M lbs) |
Peñasquito | 31,400 | 0.29 | 200 | 176,600 | 0.26 | 1,020 | 208,000 | 0.27 | 1,230 |
Table 1-6: Inferred Mineral Resource Statement (Lead)
| | | | | | | | | | | |
Area | Inferred Mineral Resources |
Tonnage (x 1,000 t) | Grade (% Pb) | Contained Lead (M lbs) |
Peñasquito | 89,800 | 0.2 | 480 |
| | | | | | | | |
Date: February 2022 | | Page 1-8 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Table 1-7: Measured and Indicated Mineral Resource Statement (Zinc)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Measured Mineral Resources | Indicated Mineral Resources | Measured and Indicated Mineral Resources |
Tonnage (x 1,000 t) | Grade (% Zn) | Contained Zinc (M lbs) | Tonnage (x 1,000 t) | Grade (% Zn) | Contained Zinc (M lbs) | Tonnage (x 1,000 t) | Grade (% Zn) | Contained Zinc (M lbs) |
Peñasquito | 31,400 | 0.66 | 460 | 176,600 | 0.57 | 2,230 | 208,000 | 0.59 | 2,690 |
Table 1-8: Inferred Mineral Resource Statement (Zinc)
| | | | | | | | | | | |
Area | Inferred Mineral Resources |
Tonnage (x 1,000 t) | Grade (% Zn) | Contained Zinc (M lbs) |
Peñasquito | 89,800 | 0.5 | 1,070 |
Notes to accompany mineral resource tables:
1.Mineral resources are current as at December 31, 2021. Mineral resources are reported using the definitions in SK1300 on a 100% basis. The Qualified Person responsible for the estimate is Mr. Donald Doe, RM SME, Group Executive, Reserves, a Newmont employee.
2.The reference point for the mineral resources is in situ.
3.Mineral resources are reported exclusive of mineral reserves. Mineral resources that are not mineral reserves do not have demonstrated economic viability.
4.Mineral resources that are potentially amenable to open pit mining methods are constrained within a designed pit . Parameters used are included in Table 11-1
5.Tonnages are metric tonnes rounded to the nearest 100,000. Gold and silver grades re rounded to the nearest 0.01 grams per tonne. Lead and zinc grade is reported as a %. Gold and silver ounces and lead and zinc pounds are estimates of metal contained in tonnages and do not include allowances for processing losses. Contained (cont.) gold and silver ounces are reported as troy ounces, rounded to the nearest 10,000. Lead and zinc are reported as pounds. Rounding of tonnes and contained metal content as required by reporting guidelines may result in apparent differences between tonnes, grade and contained metal content. Due to rounding, some cells may show a zero (“0”).
6.Totals may not sum due to rounding.
1.11.3 Factors That May Affect the Mineral Resource Estimate
Areas of uncertainty that may materially impact the mineral resource estimates include: changes to long-term commodity price assumptions; changes in local interpretations of mineralization geometry and continuity of mineralized zones; changes to geological shape and continuity assumptions; changes to metallurgical recovery assumptions; changes to the operating cut-off assumptions for mill feed or stockpile feed; changes to the input assumptions used to derive the conceptual open pit outlines used to constrain the estimate; changes to drill hole spacing assumptions; changes to the cut-off grades used to constrain the estimates; variations in geotechnical, hydrogeological and mining assumptions; changes to governmental regulations; changes to environmental assessments; and changes to environmental, permitting and social license assumptions.
| | | | | | | | |
Date: February 2022 | | Page 1-9 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
1.12 Mineral Reserve Estimation
1.12.1 Estimation Methodology
Measured and indicated mineral resources were converted to mineral reserves. Mineral reserves were estimated assuming open pit mining, and the use of conventional Owner-operated equipment. Mineral reserves include mineralization within the Peñasco and Chile Colorado open pits, and stockpiled material. All Inferred blocks are classified as waste in the cashflow analysis that supports mineral reserve estimation.
For mineral reserves, Newmont applies a time discount factor to the dollar value block model that is generated in the pit-limit analysis, to account for the fact that a pit will be mined over a period of years, and that the cost of waste stripping in the early years must bear the cost of the time value of money. Optimization work involved floating pit shells at a series of gold prices. The generated nested pit shells were evaluated using the reserve metal prices of US$1,200/oz for gold, US$20/oz for silver, US$0.90/lb for lead, and US$1.15/lb for zinc and an 8% discount rate. The pit shells with the highest NPV were selected for detailed engineering design work. A realistic schedule was developed in order to determine the optimal pit shell for each deposit; schedule inputs include the minimum mining width, and vertical rate of advance, mining rate and mining sequence.
The mine plan is based on a 36 Mt/a mill throughput. The schedule was developed at an NSR cut-off of US$14.61/t, incorporating processing costs, metallurgical recovery, incremental ore mining costs, process sustaining capital and TSF-related rehabilitation costs. The net revenue calculation assumes the same commodity prices as used in optimization. The assumed exchange rate for mineral reserves was 19.5 Mexican pesos per US$. Mineral reserves are reported above an NSR cut-off of US$14.61/t.
Pit designs are full crest and toe detailed designs with final ramps based on the selected optimum Whittle cones. Pit designs honor geotechnical guidelines.
Dilution and ore loss are included in the block model.
Stockpile estimates were based on mine dispatch data; the grade comes from closely-spaced blasthole sampling and tonnage sourced from truck factors. The stockpile volumes were typically updated based on monthly surveys. The average grade of the stockpiles was adjusted based on the material balance to and from the stockpile.
Mineral reserves that will be mined using open pit mining methods are reported within a mine design. Commodity prices used in mineral reserve estimation are based on long-term analyst and bank forecasts, supplemented with research by Newmont’s internal specialists. The estimated timeframe used for the price forecasts is the 10-year LOM that supports the mineral reserve estimates.
1.12.2 Mineral Reserve Statement
Mineral reserves have been classified using the mineral reserve definitions set out in SK1300 on a 100% basis. The estimates are current as at December 31, 2021. The reference point for the mineral reserve estimate is the point of delivery to the process facilities.
Mineral reserves are reported in Table 1-9. Tonnages in the table are metric tonnes.
| | | | | | | | |
Date: February 2022 | | Page 1-10 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
1.12.3 Factors That May Affect the Mineral Reserve Estimate
Areas of uncertainty that may materially impact the mineral reserve estimates include: changes to long-term metal price and exchange rate assumptions; changes to metallurgical recovery assumptions; changes to the input assumptions used to derive the pit designs applicable to the open pit mining methods used to constrain the estimates; changes to the forecast dilution and mining recovery assumptions; changes to the cut-off values applied to the estimates; variations in geotechnical (including seismicity), hydrogeological and mining method assumptions; and changes to environmental, permitting and social license assumptions.
1.13 Mining Methods
Open pit mining is conducted using conventional techniques and an Owner-operated conventional truck and shovel fleet. The Peñasco and Chile Colorado deposits are actively being mined.
The geotechnical model is based on information from geotechnical drilling and logging, laboratory test work, rock mass classification, structural analysis and stability modeling. Pit slope angles are based on inputs from third-party consultants and Newmont staff. As mining operations progress in the pit, additional geotechnical drilling and stability analysis will continue to be conducted to support optimization of the geotechnical parameters in the LOM designs.
A combination of Newmont staff and external consultants have developed the pit water management program, completed surface water studies, and estimated the life- of-mine site water balance. Management of water inflows to date have been appropriate, and no hydrological issues that could impact mining operations have been encountered.
| | | | | | | | |
Date: February 2022 | | Page 1-11 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Table 1-9: Mineral Reserves Statement (Gold)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Proven Mineral Reserves | Probable Mineral Reserves | Proven and Probable Mineral Reserves |
Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) |
Peñasquito | 115,000 | 0.61 | 2,250 | 247,000 | 0.51 | 4,080 | 362,000 | 0.54 | 6,330 |
Table 1-10: Mineral Reserves Statement (Silver)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Proven Mineral Reserves | Probable Mineral Reserves | Proven and Probable Mineral Reserves |
Tonnage (x 1,000 t) | Grade (g/t Ag) | Cont. Silver (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Ag) | Cont. Silver (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Ag) | Cont. Silver (x 1,000 oz) |
Peñasquito | 115,000 | 38.26 | 141,460 | 247,000 | 31.78 | 252,430 | 362,000 | 33.84 | 393,880 |
Table 1-11: Mineral Reserves Statement (Lead)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Proven Mineral Reserves | Probable Mineral Reserves | Proven and Probable Mineral Reserves |
Tonnage (x 1,000 t) | Grade (% Pb) | Contained Lead (M lbs) | Tonnage (x 1,000 t) | Grade (% Pb) | Contained Lead (M lbs) | Tonnage (x 1,000 t) | Grade (% Pb) | Contained Lead (M lbs) |
Peñasquito | 115,000 | 0.37 | 940 | 247,000 | 0.30 | 1,640 | 362,000 | 0.32 | 2,580 |
| | | | | | | | |
Date: February 2022 | | Page 1-12 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Table 1-12: Mineral Reserves Statement (Zinc)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Proven Mineral Reserves | Probable Mineral Reserves | Proven and Probable Mineral Reserves |
Tonnage (x 1,000 t) | Grade (% Zn) | Contained Zinc (M lbs) | Tonnage (x 1,000 t) | Grade (% Zn) | Contained Zinc (M lbs) | Tonnage (x 1,000 t) | Grade (% Zn) | Contained Zinc (M lbs) |
Peñasquito | 115,000 | 0.94 | 2,380 | 247,000 | 0.71 | 3,870 | 362,000 | 0.78 | 6,250 |
Notes to accompany mineral reserve tables:
1.Mineral reserves current as at December 31, 2021. Mineral reserves are reported using the definitions in SK1300 on a 100% basis. he Qualified Person responsible for the estimate is Mr. Donald Doe, RM SME, Group Executive, Reserves, a Newmont employee.
2.The reference point for the mineral reserves is the point of delivery to the process plant.
3.Mineral reserves are confined within open pit designs. Parameters used are summarized in Table 12-1.
4.Tonnages are metric tonnes rounded to the nearest 100,000. Gold and silver grades re rounded to the nearest 0.01 grams per tonne. Lead and zinc grade is reported as a %. Gold and silver ounces and lead and zinc pounds are estimates of metal contained in tonnages and do not include allowances for processing losses. Contained (cont.) gold and silver ounces are reported as troy ounces, rounded to the nearest 10,000. Lead and zinc are reported as pounds. Rounding of tonnes and contained metal content as required by reporting guidelines may result in apparent differences between tonnes, grade and contained metal content. Due to rounding, some cells may show a zero (“0”).
5.Totals may not sum due to rounding.
| | | | | | | | |
Date: February 2022 | | Page 1-13 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
The Peñasquito pit has four remaining stages (Phases 6 to 9), and will be excavated to a total depth of 780 m. The Chile Colorado pit has one remaining stage (Phase 2), and will reach 461 m ultimate depth. An ore stockpiling strategy is practiced.
The remaining mine life is 10 years, with the last year, 2031, being a partial year. The open pit operations will progress at a nominal annual mining rate of 193 Mt/a until the end of 2023, subsequently decreasing to a nominal mining rate of 144 Mt/a until the end of 2027. The LOM plan assumes a nominal rate of 36 Mt/a milling to 2031.
1.14 Recovery Methods
The Peñasquito Operations currently consist of a sulfide plant that processes a maximum of 119,000 t/d of sulfide ore. The sulfide process plant design was based on a combination of metallurgical testwork, previous study designs, and previous operating experience. The design is conventional to the gold industry and has no novel parameters.
Active loading of the oxide heap leach pad ceased in 2020. The heap leach pad is being recirculated with water while closure plans are under development.
The sulfide plant consists of the following units: coarse ore stockpile; grinding (semi-autogenous grind (SAG) and ball) mills circuit; augmented feed circuit (cone crusher, pebble crusher and high-pressure grind roll (HPGR)) and carbon, lead and zinc flotation circuits.
A pyrite leach process circuit treats the zinc rougher tailing from the concentrator for recovery of residual gold and silver. The process comprises pyrite rougher and cleaner flotation, pre-cleaner concentrate regrinding, pyrite thickening, and post-cleaner regrind, agitated tank leaching, counter-current decantation, Merrill-Crowe precipitation, precious metals refining and a cyanide detoxification circuit. The pyrite leach process circuit produces doré bars.
The tertiary precious metals recovery process has not been commissioned because, as of the Report date, the organic carbon grades had not been high enough to operate this circuit. It is expected that organic carbon grades will increase after mid-2022 and the circuit will become operational from that point onward. The tertiary precious metals recovery circuit was installed to minimize precious metal lost with the carbon pre-flotation process carbon concentrate, and to indirectly recover precious metal value associated with the pyrite leach process pre-leach flotation concentrate, which will be directed to the carbon pre-treatment cleaner flotation cells. Without the tertiary precious metals recovery plant, the carbon concentrate and contained gold and silver values would be directed to tailings.
Newmont currently uses power sourced from Saavi Energia (formerly Intergen) located in San Luis de la Paz, Guanajuato as its central power grid; however, the Peñasquito Operations are still using Mexican Electricity Federal Commission infrastructure to bring the electricity from Guanajuato to Mazapil. Water is sourced from several locations: the TSF, well fields, pit dewatering wells, and process operational recycle streams. Consumables used in the processing include collectors, depressants, frothers, activators, flocculants, and zinc dust.
| | | | | | | | |
Date: February 2022 | | Page 1-14 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
1.15 Project Infrastructure
The key infrastructure to support the Peñasquito Operations mining activities envisaged in the LOM is in place. Personnel reside in an on-site accommodation complex.
Stockpile classification is based on material types that require different treatment at the mill, with three major stockpile types, organic carbon (<0.30% C), low lead (<0.20% Pb), and high lead (>0.20% Pb). The high-lead stockpile is subdivided into three types, based on gold content, which are designated low (<0.30 g/t Au), medium (>0.30–<0.49 g/t au), and high (>0.50 g/t Au).
Five WRSFs will store the LOM waste rock requirements. There is sufficient capacity in these WRSFs for LOM requirements.
Four perimeter containment structures, the north, south, east, and west dams, provide containment of the tailings at the existing TSF.
The maximum storage allowed under the current tailings dam construction plan at elevation 1907.7 masl is 383 Mt, consisting of 356 Mt of stored tailings and 27 Mt of hydraulic sand construction. This is sufficient for the current LOM plan.
The water supply for the Peñasquito Operations is obtained from groundwater in the Cedros basin, from an area known as the Torres and Vergel well field. As much water as practicable is recycled. Newmont continues to monitor the local aquifers to ensure they remain sustainable. A network of monitoring wells was established to monitor water levels and water quality.
Water management infrastructure for mine operations includes pit dewatering and mine surface water drainage infrastructure.
Power is currently supplied from the 182 MW power purchase agreement with Saavi Energia, delivered to the mine by the Mexican Federal Electricity Commission. The Federal Electricity Commission continues to provide backup power supply for both planned and unplanned shutdowns from the Saavi Energia power plant.
1.16 Environmental, Permitting and Social Considerations
1.16.1 Environmental Studies and Monitoring
Baseline and supporting environmental studies were completed to assess both pre-existing and ongoing site environmental conditions, as well as to support decision-making processes during operations start-up. Characterization studies were completed that included the following: hydrogeology and groundwater quality; aquifer assessments; surface water quality and sediment; metals toxicity and acid mine drainage studies; air and climate; noise and vibration; vegetation; wildlife; conservation area management plan; biomass and carbon fixation studies; land use and resources; and socio-economics.
Environmental monitoring is ongoing at the Project and will continue over the life of the operations. Key monitoring areas include air, water, noise, wildlife, forest resources and waste management.
| | | | | | | | |
Date: February 2022 | | Page 1-15 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
1.16.2 Closure and Reclamation Considerations
A closure and reclamation plan was prepared for the mine site, and updated in accordance with applicable laws. The cost for this plan was calculated based on the standard reclamation cost estimator (SRCE) model which is based on the Nevada State regulations.
The closure costs used in the economic analysis total US$0.8 B.
A comprehensive study is ongoing to determine potential resettlement and the associated costs involved in resettling communities close to the mine. Any such plan is subject to approval from Newmont’s senior management, and will impact future closure cost estimates.
1.16.3 Permitting
All major permits and approvals are in place to support operations. Where permits have specific terms, renewal applications are made of the relevant regulatory authority as required, prior to the end of the permit term.
Newmont monitors the regulatory regime in place at each of its operations and ensures that all permits are updated in line with any regulatory changes.
1.16.4 Social Considerations, Plans, Negotiations and Agreements
Public consultation and community assistance and development programs are ongoing.
Newmont, Ejido Cedros and Ejido Mazapil have established trust funds for locally-managed infrastructure, education and health projects. Newmont provides annual funding for these trusts. The communities around the Peñasquito mine also benefit from a number of programs and services provided, or supported, by the mine.
1.17 Markets and Contracts
Newmont has established contracts and buyers for its lead and zinc concentrate, and has a corporate internal marketing group that monitors markets for its concentrate. Together with public documents and analyst forecasts, these data support that there is a reasonable basis to assume that for the LOM plan, that the lead and zinc concentrate will be saleable at the assumed commodity pricing.
Doré is sold on the spot market, by corporate in-house marketing experts. The terms in these contracts are in line with industry standard terms and are consistent with doré sold from other operations. The doré is not subject to product specification requirements.
Newmont uses a combination of historical and current contract pricing, contract negotiations, knowledge of its key markets from a long operations production record, short-term versus long-term price forecasts prepared by Newmont’s corporate internal marketing group, public documents, and analyst forecasts when considering long-term commodity price forecasts.
Higher metal prices are used for the mineral resource estimates to ensure the mineral reserves are a sub-set of, and not constrained by, the mineral resources, in accordance with industry-accepted practice.
| | | | | | | | |
Date: February 2022 | | Page 1-16 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
The largest in-place contracts other than for product sales cover items such as bulk commodities, operational and technical services, mining and process equipment, and administrative support services. Contracts are negotiated and renewed as needed. Contract terms are typical of similar contracts in Mexico that Newmont is familiar with.
1.18 Capital Cost Estimates
Capital cost estimates are at a minimum at a pre-feasibility level of confidence, having an accuracy level of ±25% and a contingency range not exceeding 15%.
Capital costs are based on recent prices or operating data. Capital costs include funding for infrastructure, pit dewatering, development drilling, and permitting as well as miscellaneous expenditures required to maintain production. Mobile equipment re-build/replacement schedules and fixed asset replacement and refurbishment schedules are included. Sustaining capital costs reflect current price trends.
The overall capital cost estimate for the LOM is US$1.1 B, as summarized in Table 1-13.
1.19 Operating Cost Estimates
Operating cost estimates are at a minimum at a pre-feasibility level of confidence, having an accuracy level of ±25% and a contingency range not exceeding 15%.
Operating costs are based on actual costs seen during operations and are projected through the LOM plan. Historical costs are used as the basis for operating cost forecasts for supplies and services unless there are new contract terms for these items. Labor and energy costs are based on budgeted rates applied to headcounts and energy consumption estimates.
Operating costs for the LOM are estimated at US$7.4 B, as summarized in Table 1-14. The estimated LOM mining cost is US$2.03/t. Base processing costs are estimated at US$10.25/t. In addition, G&A costs are estimated at US$3.40/t.
1.20 Economic Analysis
1.20.1 Economic Analysis
The financial model that supports the mineral reserve declaration is a standalone model that calculates annual cash flows based on scheduled ore production, assumed processing recoveries, metal sale prices and MXN$/US$ exchange rate, projected operating and capital costs and estimated taxes.
The financial analysis is based on an after-tax discount rate of 8%. All costs and prices are in unescalated “real” dollars. The currency used to document the cash flow is US$.
All costs are based on the 2022 budget. Revenue is calculated from the recoverable metals and long-term metal price and exchange rate forecasts.
The Peñasquito Operations are subject to a federal tax of 30%, and mining tax of 7.5%.
The economic analysis assumes constant prices with no inflationary adjustments.
| | | | | | | | |
Date: February 2022 | | Page 1-17 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
The NPV8% is US$1.7 B. As the cashflows are based on existing operations where all costs are considered sunk to 1 January 2022, considerations of payback and internal rate of return are not relevant.
A summary of the financial results is provided in Table 1-15. In this table, EBITDA = earnings before interest, taxes, depreciation and amortization. The active mining operation ceases in 2031; however, closure costs are estimated to 2071.
Table 1-13: Capital Cost Estimate
| | | | | | | | |
Area | Unit | Value |
Mining | US$ B | 0.3 |
Process | US$ B | 0.5 |
Site G&A | US$ B | 0.4 |
Total | US$ b | 1.1 |
Note: Numbers have been rounded; totals may not sum due to rounding.
Table 1-14: Operating Cost Estimate
| | | | | | | | |
Area | Unit | Value |
Mining | US$ B | 2.5 |
Process | US$ B | 3.7 |
G&A | US$ B | 1.2 |
Total | US$ B | 7.4 |
Note: Numbers have been rounded; totals may not sum due to rounding.
| | | | | | | | |
Date: February 2022 | | Page 1-18 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Table 1-15: Cashflow Summary Table
| | | | | | | | |
Item | Unit | Value |
Metal Prices |
Gold | US$/oz | 1,200 |
Silver | US$/oz | 20 |
Lead | US$/lb | 0.90 |
Zinc | US$/lb | 1.15 |
Mined Ore |
Tonnage | Mtonnes | 362 |
Gold grade | g/t | 0.54 |
Silver grade | g/t | 33.84 |
Lead grade | % | 0.32 |
Zinc grade | % | 0.78 |
Gold ounces | Moz | 6.3 |
Silver ounces | Moz | 394 |
Lead pounds | Blb | 2.6 |
Zinc pounds | Blb | 6.2 |
Capital costs | US$B | 1.1 |
Costs applicable to sales | US$B | 8.8 |
Discount rate | % | 8 |
Exchange rate | United States dollar:Mexican peso (USD:MXN) | 19.5 |
Free cash flow | US$B | 2.3 |
Net present value | US$B | 1.7 |
Note: Numbers have been rounded; totals may not sum due to rounding. Table 1-15 contains “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, which are intended to be covered by the safe harbor created by such sections and other applicable laws. Please refer to the note regarding forward-looking information at the front of the Report. The cash flow is only intended to demonstrate the financial viability of the Project. Investors are cautioned that the above is based upon certain assumptions which may differ from Newmont’s long-term outlook or actual financial results, including, but not limited to commodity prices, escalation assumptions and other technical inputs. For example, Table 1-15 uses the price assumptions stated in the table, including a gold commodity price assumption of US$1,200/oz, which varies significantly from current gold prices and the assumptions that Newmont uses for its long-term guidance. Please be reminded that significant variation of metal prices, costs and other key assumptions may require modifications to mine plans, models, and prospects.
1.20.2 Sensitivity Analysis
The sensitivity of the Project to changes in metal prices, exchange rate, sustaining capital costs and operating cost assumptions was tested using a range of 25% above and below the base case values (Figure 1-1).
The Project is most sensitive to metal price changes, less sensitive to changes in operating costs, and least sensitive to changes in capital costs.
The sensitivity to grade mirrors the sensitivity performed for the commodity prices and is not shown.
| | | | | | | | |
Date: February 2022 | | Page 1-19 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
1.21 Risks and Opportunities
Factors that may affect the mineral resource and mineral reserve estimates are summarized in Chapter 1.11.3 and Chapter 1.12.3.
1.21.1 Risks
The risks associated with the Peñasquito Operations are generally those expected with open pit mining operations and include the accuracy of the resource model, unexpected geological features that cause geotechnical issues, and/or operational impacts.
Other risks noted include:
•Commodity price increases for key consumables such as diesel, electricity, tires and chemicals would negatively impact the stated mineral reserves and mineral resources;
•Labor cost increases or productivity decreases could also impact the stated mineral reserves and mineral resources, or impact the economic analysis that supports the mineral reserves;
•Geotechnical and hydrological assumptions used in mine planning are based on historical performance, and to date historical performance has been a reasonable predictor of current conditions. Any changes to the geotechnical and hydrological assumptions could affect mine planning, affect capital cost estimates if any major rehabilitation is required due to a geotechnical or hydrological event, affect operating costs due to mitigation measures that may need to be imposed, and impact the economic analysis that supports the mineral reserve estimates;
•The mineral resource estimates are sensitive to metal prices. Lower metal prices require revisions to the mineral resource estimates;
•Risk to assumed process recoveries if the organic carbon present cannot be successfully mitigated during processing;
•While there is sufficient space within the TSF for the planned LOM operations, if mineral resources are converted to mineral reserves, additional storage capacity will be required. Any expansion of the TSF is likely to require community relocation;
| | | | | | | | |
Date: February 2022 | | Page 1-20 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Figure 1-1: NPV Sensitivity
Note: Figure prepared by Newmont, 2021. FCF = free cashflow; op cost = operating cost; cap cost = capital cost; NPV = net present value.
•There are communities that are within the zone of influence of the TSF that can potentially be affected by control failures at the TSF. Newmont continues to study relocation options for these communities, but there is a risk that impacted stakeholders are not amenable to relocation;
•While water supplies are well understood for the LOM operations, supplementary water studies would be required if additional mineral reserves are added to the LOM plan in the future;
•Climate changes could impact operating costs and ability to operate;
•Assumptions that the long-term reclamation and mitigation of the Peñasquito Operations can be appropriately managed within the estimated closure timeframes and closure cost estimates;
•Political risk from challenges to:
◦Mining licenses;
◦Environmental permits;
◦Newmont’s right to operate;
•Changes to assumptions as to governmental tax or royalty rates, such as taxation rate increases or new taxation or royalty imposts.
| | | | | | | | |
Date: February 2022 | | Page 1-21 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
1.21.2 Opportunities
Opportunities for the Peñasquito Operations include moving the stated mineral resources into mineral reserves through additional drilling and study work. The mineral reserves and mineral resources are based on conservative price estimates for gold, silver, lead, and zinc so upside exists, either in terms of the potential to estimate additional mineral reserves and mineral resources or improved economics should the price used for these metals be increased.
Opportunities include:
•Conversion of some or all of the measured and indicated mineral resources currently reported exclusive of mineral reserves to mineral reserves, with appropriate supporting studies;
•Upgrade of some or all of the inferred mineral resources to higher-confidence categories, such that better-confidence material could be used in mineral reserve estimation;
•Higher metal prices than forecast could present upside sales opportunities and potentially an increase in predicted Project economics;
•Newmont holds a significant ground package around the Peñasquito Operations that retains exploration potential.
1.22 Conclusions
Under the assumptions presented in this Report, the Peñasquito Operations have a positive cash flow, and mineral reserve estimates can be supported.
1.23 Recommendations
As the Peñasquito Operations are an operating mine, the QP has no material recommendations to make.
| | | | | | | | |
Date: February 2022 | | Page 1-22 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
2.0 INTRODUCTION
2.1 Introduction
This technical report summary (the Report) was prepared for Newmont Corporation (Newmont) on the Peñasquito Operations (Peñasquito Operations or the Project) located in Zacatecas State, Mexico. The location of the operations is shown in Figure 2-1.
The operating entity is an indirectly wholly-owned Newmont subsidiary, Minera Peñasquito S.A. de C.V. (Minera Peñasquito). For the purpose of this Report, “Newmont” is used interchangeably to refer to the parent and the fully owned subsidiary companies in Mexico.
The Peñasquito Operations contain the Peñasco and Chile Colorado deposits. Open pit mining commenced in 2010, and commercial production was reached during 2011. The open pit feeds a sulfide concentrator (mill).
2.2 Terms of Reference
2.2.1 Report Purpose
The Report was prepared to be attached as an exhibit to support mineral property disclosure, including mineral resource and mineral reserve estimates, for the Peñasquito Operations in Newmont’s Form 10-K for the year ending December 31, 2021.
Mineral resources and mineral reserves are reported for Peñasco and Chile Colorado. Mineral reserves are also estimated for material in stockpiles.
2.2.2 Terms of Reference
The Peñasquito Operations consist of an open pit mine. Mining commenced in 2008.
All measurement units used in this Report are metric unless otherwise noted, and currency is expressed in United States (US$) dollars as identified in the text. The Mexican currency is the peso.
Unless otherwise indicated, all financial values are reported in US$.
Unless otherwise indicated, the metric system is used in this Report.
Mineral resources and mineral reserves are reported using the definitions in Regulation S–K 1300 (SK1300), under Item 1300.
The Report uses US English.
The Report contains forward-looking information; refer to the note regarding forward-looking information at the front of the Report.
| | | | | | | | |
Date: February 2022 | | Page 2-1 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Figure 2-1: Project Location Plan
| | | | | | | | |
Date: February 2022 | | Page 2-2 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
2.3 Qualified Persons
This Report was prepared by the following Newmont Qualified Person (QP):
•Mr. Donald Doe, RM SME, Group Executive Reserves, Newmont.
Mr. Doe is responsible for all Report Chapters.
2.4 Site Visits and Scope of Personal Inspection
Mr. Doe visited the Peñasquito Operations most recently from October 25 to 29, 2021. During this site visit, he inspected the operating open pits, visited the core shed, and viewed the general locations planned for the additional laybacks in the mine plan. Mr. Doe also viewed the process plant and associated general site infrastructure, including the current tailings storage facility (TSF) operations.
While on site, he discussed aspects of the operation with site-based staff. These discussions included the overall approach to the mine plan, anticipated mining conditions, selection of the production target and potential options for improvement, as well as reconciliation study results. Other areas of discussion included plant operation and recovery forecasts. Mr. Doe reviewed capital and operating forecasts with site staff.
Mr. Doe also reviewed Newmont’s processes and the internal controls on those processes at the mine site with operational staff on the work flow for determining mineral resource and mineral reserve estimates, mineral process performance, production forecasts, mining costs, and waste management.
2.5 Report Date
Information in this Report is current as at December 31, 2021.
2.6 Information Sources and References
The reports and documents listed in Chapter 24 and Chapter 25 of this Report were used to support Report preparation.
2.7 Previous Technical Report Summaries
Newmont has not previously filed a technical report summary on the Project.
| | | | | | | | |
Date: February 2022 | | Page 2-3 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
3.0 PROPERTY DESCRIPTION AND LOCATION
3.1 Introduction
The Peñasquito Operations are situated in the western half of the Concepción Del Oro district in the northeast corner of Zacatecas State, Mexico, approximately 200 km northeast of the city of Zacatecas.
Project centroid co-ordinates are approximately 24°45’N latitude/101° 30’W longitude. The Peñasquito pit is located at approximately 24.645268 N latitude, -101.655332 W latitude. The Chile Colorado pit is located at 24.659521 N latitude and -101.636357W longitude.
3.2 Property and Title in Mexico
3.2.1 Mineral Title
In Mexico, mining concessions are granted by the Economy Ministry and are considered exploitation concessions with a 50-year term.
Valid mining concessions can be renewed for an additional 50-year term as long as the mine is active, and the applicant has abided by all appropriate regulations and makes the application within five years prior to the expiration date.
All concessions must be surveyed by a licensed surveyor.
Mining concessions have an annual minimum investment that must be met, an annual mining rights fee to be paid to keep the concessions effective, and compliance with environmental laws. Minimum expenditures, pursuant to Mexican regulations, may be substituted for sales of minerals from the mine for an equivalent amount.
3.2.2 Surface Rights
Surface rights in Mexico are commonly owned either by communities (ejidos) or by private owners. The Mexican Mining Law includes provisions to facilitate purchasing land required for mining activities, installations and development.
3.2.3 Water Rights
The National Water Law and associated regulations control all water use in Mexico. The Comisión Nacional del Agua (CNA) is the responsible agency. Applications are submitted to this agency indicating the annual water needs for the mine operation and the source of water to be used. The CNA grants water concessions based on water availability in the source area.
| | | | | | | | |
Date: February 2022 | | Page 3-1 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
3.3 Project Ownership
The Project is indirectly 100% held by Newmont. Newmont uses an indirectly 100% owned subsidiary, Minera Peñasquito SA de C.V. (Minera Peñasquito), as the operating entity for the mining operations.
Newmont acquired the project as part of the merger with Goldcorp in 2019.
3.4 Mineral Tenure
Newmont currently holds 77 mining concessions (approximately 82,632 ha). Claims are summarized in Table 3-1, and the claim locations are shown in Figure 3-1.
As per Mexican requirements for grant of tenure, the concessions comprising the Project were surveyed by a licensed surveyor. Duty payments for the concessions have been made as required.
The mining operations are within the Las Peñas, Alfa, La Peña and El Peñasquito concessions.
3.5 Surface Rights
Newmont has entered into agreements with a number of ejidos in relation to surface rights, either for mining or exploration activities, as summarized in Table 3-2.
Under current agreements with the ejidos, payments are made to the ejidos on an annual basis, in addition to certain upfront payments that have already been made. All temporary occupancy (such as land use) agreements are filed with the Public Agrarian Registry and the Public Mining Registry.
Surface rights in the vicinity of the Chile Colorado and Peñasco open pits are held by four ejidos: Ejido Cedros, Ejido Mazapil, Ejido El Vergel and Ejido Cerro Gordo (Figure 3-2).
Newmont entered into easement agreements with individual parcel owners for the construction and maintenance of the La Pardita–Cedros Highway, as well as easement agreements in relation to the construction and maintenance of the El Salero–Peñasquito powerline.
All required power line and road easements have been granted.
| | | | | | | | |
Date: February 2022 | | Page 3-2 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Table 3-1: Mineral Tenure Table
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
No. | Name | File | Title | Validity | Area (ha) | Holder | Mining Unit | Municipality | State |
From | To |
1 | Ampl. A El Cobrizo | 007/08625 | 169240 | 10/27/1981 | 10/26/2031 | 28.6871 | MP | Peñasquito | Mazapil | Zac. |
2 | La Negra | 007/00864 | 170048 | 3/15/1982 | 3/14/2032 | 31.6127 | MP | Peñasquito | Mazapil | Zac. |
3 | La Santa Cruz | 007/00930 | 170049 | 3/15/1982 | 3/14/2032 | 13.5196 | MP | Peñasquito | Mazapil | Zac. |
4 | Las Tres Estrellas | 007/01469 | 170050 | 3/15/1982 | 3/14/2032 | 8.2248 | MP | Peñasquito | Mazapil | Zac. |
5 | San Vicente | 321.43/917 | 170560 | 5/13/1982 | 5/12/2032 | 2 | MP | Peñasquito | Mazapil | Zac. |
6 | La Cruz | 321.42/918 | 170678 | 6/11/1982 | 6/10/2032 | 2.9772 | MP | Peñasquito | Mazapil | Zac. |
7 | El Encino | 321.42/914 | 170997 | 8/5/1982 | 5/4/2032 | 13.3792 | MP | Peñasquito | Mazapil | Zac. |
8 | Santa Ana y Santa Rita | 321.43/1006 | 172662 | 6/28/1984 | 6/27/2034 | 2 | MP | Peñasquito | Mazapil | Zac. |
9 | La Favorita | 007/08420 | 172859 | 6/29/1984 | 6/28/2034 | 21.1612 | MP | Peñasquito | Mazapil | Zac. |
10 | San José | 321.43/1067 | 176503 | 12/12/1985 | 12/11/2035 | 1 | MP | Peñasquito | Mazapil | Zac. |
11 | El Cobrizo | 321.43/1031 | 181411 | 9/18/1987 | 9/17/2037 | 1 | MP | Peñasquito | Mazapil | Zac. |
12 | Morena | 321.1/7-150 | 187089 | 5/30/1990 | 5/29/2040 | 79.2102 | MP | Peñasquito | Mazapil | Zac. |
13 | Rosa María | 321.1/7-153 | 188193 | 11/22/1990 | 11/21/2040 | 34.8928 | MP | Peñasquito | Mazapil | Zac. |
14 | Macocozac | 321.43/1185 | 188619 | 11/29/1990 | 11/28/2040 | 5 | MP | Peñasquito | Mazapil | Zac. |
15 | El Coyote | 321.1/7-152 | 190779 | 4/29/1991 | 4/28/2041 | 15 | MP | Peñasquito | Mazapil | Zac. |
16 | El Cármen | 321.1/7-151 | 191793 | 12/19/1991 | 12/18/2041 | 71.2921 | MP | Peñasquito | Mazapil | Zac. |
17 | La Peña | 7/1.3/547 | 203264 | 6/28/1996 | 6/27/2046 | 58 | MP | Peñasquito | Mazapil | Zac. |
18 | El Rayo | 321.43/1002 | 204131 | 12/18/1996 | 5/30/2036 | 2 | MP | Peñasquito | Mazapil | Zac. |
19 | Beta | 8/1.3/01137 | 211970 | 8/18/2000 | 8/17/2050 | 2,055 | MP | Peñasquito | Mazapil | Zac. |
20 | Las Peñas | 8/1.3/00983 | 212290 | 9/29/2000 | 9/28/2050 | 40 | MP | Peñasquito | Mazapil | Zac. |
21 | Santa María | 8/1.3/00999 | 214769 | 11/29/2001 | 11/28/2051 | 3.8534 | MP | Peñasquito | Mazapil | Zac. |
22 | Paraiso | 093/24846 | 215437 | 2/19/2002 | 2/18/2052 | 96.6747 | MP | Peñasquito | Mazapil | Zac. |
23 | Paraiso | 093/24845 | 215457 | 2/22/2002 | 2/21/2052 | 95 | MP | Peñasquito | Mazapil | Zac. |
24 | Paraiso | 093/24847 | 215458 | 2/22/2002 | 2/21/2052 | 75.9503 | MP | Peñasquito | Mazapil | Zac. |
25 | Paraiso | 093/25816 | 215468 | 2/22/2002 | 2/21/2052 | 93.007 | MP | Peñasquito | Mazapil | Zac. |
26 | Mazapil 4 | 007/13859 | 215503 | 2/22/2002 | 2/21/2052 | 4,355 | MP | Peñasquito | Mazapil | Zac. |
27 | C. del Oro 2 | 8/1.3/01377 | 216928 | 6/5/2002 | 6/4/2052 | 1,947 | MP | S/Agrupamto | Mazapil | Zac. |
28 | Mazapil 3 Frac. I | 007/13852 | 217001 | 6/14/2002 | 6/13/2052 | 1,951 | MP | Peñasquito | Mazapil | Zac. |
29 | Mazapil 3 Frac. II | 007/13852 | 217002 | 6/14/2002 | 6/13/2052 | 1,162 | MP | Peñasquito | Mazapil | Zac. |
30 | Paraiso | 093/25701 | 217178 | 7/2/2002 | 7/1/2052 | 26.842 | MP | Peñasquito | Mazapil | Zac. |
31 | Paraiso Frac. 1 | 093/25701 | 217179 | 7/2/2002 | 7/1/2052 | 12.0844 | MP | Peñasquito | Mazapil | Zac. |
32 | Paraiso Frac. 2 | 093/25701 | 217180 | 7/2/2002 | 7/1/2052 | 2.8463 | MP | Peñasquito | Mazapil | Zac. |
33 | La Blanca | 093/25822 | 217577 | 7/31/2002 | 7/30/2052 | 8.6982 | MP | Peñasquito | Mazapil | Zac. |
| | | | | | | | |
Date: February 2022 | | Page 3-3 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
No. | Name | File | Title | Validity | Area (ha) | Holder | Mining Unit | Municipality | State |
From | To |
34 | Mazapil | 8/1.3/01280 | 218409 | 11/5/2002 | 11/4/2052 | 1,476 | MP | Peñasquito | Mazapil | Zac. |
35 | Mazapil 2 | 8/1.3/01281 | 218420 | 11/5/2002 | 11/4/2052 | 2,397 | MP | Peñasquito | Mazapil | Zac. |
36 | Los Lobos | 093/26372 | 219628 | 3/26/2003 | 3/25/2053 | 9,522 | MP | Peñasquito | Mazapil | Zac. |
37 | Cerro del Oro 3 | 093/26713 | 220279 | 7/3/2003 | 7/2/2053 | 104.6815 | MP | S/Agrupamto | Mazapil | Zac. |
38 | Mazapil 8 Frac. 1 | 093/26735 | 220732 | 9/30/2003 | 9/29/2053 | 77 | MP | Peñasquito | Mazapil | Zac. |
39 | Mazapil 8 Frac. 2 | 093/26735 | 220733 | 9/30/2003 | 9/29/2053 | 235.4514 | MP | Peñasquito | Mazapil | Zac. |
40 | Mazapil 5 | 8/1/01527 | 220915 | 10/28/2003 | 10/27/2053 | 50 | MP | Peñasquito | Mazapil | Zac. |
41 | Mazapil 6 | 8/1/01528 | 220916 | 10/28/2003 | 10/27/2053 | 36 | MP | Peñasquito | Mazapil | Zac. |
42 | Alondra 2 | 093/26758 | 221416 | 2/4/2004 | 2/3/2054 | 142.9449 | MP | Peñasquito | Mazapil | Zac. |
43 | Alondra 2 Frac. 1 | 093/26758 | 221417 | 2/4/2004 | 2/3/2054 | 207.9101 | MP | Peñasquito | Mazapil | Zac. |
44 | Mazapil 9 Frac. 1 | 093/26783 | 221418 | 2/4/2004 | 2/3/2054 | 25.8394 | MP | Peñasquito | Mazapil | Zac. |
45 | Mazapil 9 Frac. 2 | 093/26783 | 221419 | 2/4/2004 | 2/3/2054 | 123.0907 | MP | Peñasquito | Mazapil | Zac. |
46 | Mazapil 7 Frac. 1 | 093/26734 | 221832 | 4/2/2004 | 4/1/2054 | 66.9372 | MP | Peñasquito | Mazapil | Zac. |
47 | Mazapil 7 Frac. 2 | 093/26734 | 221833 | 4/2/2004 | 4/1/2054 | 224.0083 | MP | Peñasquito | Mazapil | Zac. |
48 | Alondra 1 | 093/26757 | 221835 | 4/2/2004 | 4/1/2054 | 238.0724 | MP | Peñasquito | Mazapil | Zac. |
49 | Alondra 1 Frac. 1 | 093/26757 | 221836 | 4/2/2004 | 4/1/2054 | 0.8926 | MP | Peñasquito | Mazapil | Zac. |
50 | Santa Olaya Frac. I | 093/26868 | 222749 | 8/27/2004 | 8/26/2054 | 130.307 | MP | S/Agrupamto | Mazapil | Zac. |
51 | Santa Olaya Frac. II | 093/26868 | 222750 | 8/27/2004 | 8/26/2054 | 512.6659 | MP | S/Agrupamto | Mazapil | Zac. |
52 | Mazapil 10 | 93/26975 | 223327 | 12/2/2004 | 12/1/2054 | 1,074 | MP | Peñasquito | Mazapil | Zac. |
53 | Puerto Rico | 2/1/02480 | 223765 | 2/15/2005 | 2/14/2055 | 3,455 | MP | Peñasquito | El Salvador | Zac. |
54 | El Sol 2 Frac. 1 | 093/27462 | 225754 | 10/21/2005 | 10/20/2055 | 309 | MP | Peñasquito | Mazapil | Zac. |
55 | El Sol 2 Frac. 2 | 093/27462 | 225755 | 10/21/2005 | 10/20/2055 | 1,078 | MP | Peñasquito | Mazapil | Zac. |
56 | Arco Iris | 093/27390 | 226580 | 1/27/2006 | 1/26/2056 | 2,154 | MP | Peñasquito | El Salvador | Zac. |
57 | Mazapil 11 Frac. 1 | 093/27461 | 226582 | 1/27/2006 | 1/26/2056 | 1,974 | MP | Peñasquito | Mazapil | Zac. |
58 | Mazapil 11 Frac. 2 | 093/27461 | 226583 | 1/27/2006 | 1/26/2056 | 4,536 | MP | Peñasquito | Mazapil | Zac. |
59 | Mazapil 11 Frac. 3 | 093/27461 | 226584 | 1/27/2006 | 1/26/2056 | 25 | MP | Peñasquito | Mazapil | Zac. |
60 | Segunda Reduc. Concha | 8/4/00059 | 228418 | 11/7/2000 | 11/6/2050 | 23,116 | MP | Peñasquito | Mazapil | Zac. |
61 | Alfa | 8/4/00072 | 228841 | 10/11/1995 | 10/10/2045 | 1,100 | MP | Peñasquito | Mazapil | Zac. |
62 | La Pinta 06 | 093/28057 | 229764 | 6/13/2007 | 6/12/2057 | 7,875 | MP | Peñasquito | Mazapil | Zac. |
63 | Mazapil 12 | 093/28109 | 231847 | 5/7/2008 | 5/6/2058 | 2.1039 | MP | Peñasquito | Mazapil | Zac. |
64 | El Chava | 093/28246 | 231848 | 5/7/2008 | 5/6/2058 | 200 | MP | El Chava | El Salvador | Zac. |
65 | Zuloaga 3 | 007/16865 | 233448 | 2/25/2009 | 2/24/2059 | 546 | MP | Zuloaga 3 | Parras | Coah. |
66 | Mazapil 13 | 093/28842 | 234494 | 7/3/2009 | 7/2/2059 | 70.1347 | MP | Peñasquito | Mazapil | Zac. |
67 | El Chava Tres | 007/16874 | 235682 | 2/16/2010 | 2/15/2060 | 21.9392 | MP | El Chava | Galeana | N. L. |
| | | | | | | | |
Date: February 2022 | | Page 3-4 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
No. | Name | File | Title | Validity | Area (ha) | Holder | Mining Unit | Municipality | State |
From | To |
68 | Mazapil 15 | 093/29023 | 236117 | 5/11/2010 | 5/10/2060 | 53.4582 | MP | Zuloaga 3 | Melchor Ocampo | Zac. |
69 | Mazapil 14 | 093/29300 | 236118 | 5/11/2010 | 5/10/2060 | 17.401 | MP | Zuloaga 3 | Melchor Ocampo | Zac. |
70 | Mazapil 16 | 093/29341 | 236464 | 7/2/2010 | 7/1/2060 | 76.4234 | MP | Zuloaga 3 | Melchor Ocampo | Zac. |
71 | Martha | 9/6/00115 | 236745 | 11/29/1952 | 8/25/2060 | 12.1655 | MP | Peñasquito | Mazapil | Zac. |
72 | El Peñasquito | 9/6/00116 | 236746 | 6/12/1961 | 8/25/2060 | 2 | MP | Peñasquito | Mazapil | Zac. |
73 | El Cardito Dos | 093/32267 | 238754 | 10/25/2011 | 10/24/2061 | 9 | MP | Peñasquito | Mazapil | Zac. |
74 | Mazapil 20 | 093/32476 | 240688 | 6/19/2012 | 6/18/2062 | 2.9428 | MP | Zuloaga 3 | Mazapil | Zac. |
75 | El Sol Reduc | 93/27287 | 242968 | 3/16/2005 | 3/15/2055 | 709.7707 | MP | Peñasquito | Mazapil | Zac. |
76 | El Cardito Reduc. | 2/1/02439 | 244029 | 1/18/2005 | 1/17/2055 | 5,038 | MP | Peñasquito | Mazapil | Zac. |
77 | El Sol 2 Frac. 3 Reduc | 8/002- 00215 | 244812 | 10/21/2005 | 10/20/2055 | 1,289 | MP | Peñasquito | Mazapil | Zac. |
Note: MP = Minera Peñasquito. Frac. = fraccione or fraction. Zac. = Zacatecas.
| | | | | | | | |
Date: February 2022 | | Page 3-5 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Figure 3-1: Mineral Tenure Location Plan
Note: Figure prepared by Newmont, 2021.
| | | | | | | | |
Date: February 2022 | | Page 3-6 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Table 3-2: Surface Rights Agreements
| | | | | | | | | | | |
Ejido | Agreement Date | Term | Area Covered by Agreement (ha) |
Cedros | June 26, 2008 | 30 years | 1,256.50 |
March 16, 2006 | 30 years | 4,523.58 |
August 15, 2020 | 5 years | 8,028.25 |
August 15, 2020 | 30 years | 1,888.94 |
Mazapil | July 17, 2006 | 30 years | 280.80 |
August 22, 2006 | 30 years | 1,500 |
November 25, 2018 | 30 years | 6,706 |
N.C.P.A.G. El Vergel | August 21, 2013 | 29 years from January 1, 2014 to December 31 2043 | 160.10 |
June 29, 2015 | 30 years | 25.00 |
June 29, 2015 | 30 years | 25.00 |
June 29, 2015 | 30 years | 450.00 |
August 21, 2013 | 29 years from January 1, 2014 to December 31 2043 | 900.15 |
Cerro Gordo | September 28, 2005 | 30 years | 599.28 |
General Enrique Estrada | November 19, 2014 | 29 years | 128.32 |
November 19, 2014 | 29 years | 5.35 |
Tecolotes | October 30, 2014 | 29 years | 4.53 |
October 30, 2014 | 29 years | 146.21 |
October 30, 2014 | 10 years | 28.17 |
El Rodeo | December 03, 2013 | 31 years | 129.46 |
December 6, 2014 | 29 years | 150.71 |
December 6, 2014 | 29 years | 6.94 |
Matamoros | February 01, 2014 | 30 years | 134.13 |
San Antonio del Portezuelo | November 22, 2019 | 30 years | 2 |
| | | 27,079.42 |
| | | | | | | | |
Date: February 2022 | | Page 3-7 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Figure 3-2: District Surface Rights Map
Note: Figure prepared by Newmont, 2017.
| | | | | | | | |
Date: February 2022 | | Page 3-8 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
3.6 Water Rights
Hydrogeological studies were completed and indicate that the aquifers in the Cedros Basin (the groundwater basin that hosts the Project) have sufficient available water to provide 40 Mm³ per year. The operations have received permits to pump up to 35 Mm³ of this water per year.
Based on completed applications, a 4.6 Mm3 concession was obtained in August 2006 and an additional water concession of 9.1 Mm3 per year was received in early 2008.
A concession title to pump 4.837 Mm3 was received in November 2008. A concession title to pump an additional 0.450 Mm3 was obtained in April 2009, and an additional 16.87 Mm3 concession title was obtained in July 2009.
Additional information on the Project water supply is included in Section 18.4.
3.7 Property Agreements
On 24 July 2007, Goldcorp and Wheaton Precious Metals (Wheaton) entered into a transaction where Wheaton acquired 25% of the silver produced over the life-of mine (LOM) from the Peñasquito Operations for an upfront cash payment of US$485 million.
Under this transaction, Wheaton pays Newmont a per-ounce cash payment of the lesser of US$3.90 and the prevailing market price (subject to an inflationary adjustment that commenced in 2011), for silver delivered under the contract.
3.8 Royalties
A 2% net smelter return (NSR) royalty is payable to Royal Gold on production from the Chile Colorado and Peñasco deposits.
The Mexican Government levies a 7.5% mining royalty that is imposed on earnings before interest, taxes, depreciation, and amortization.
There is also a 0.5% environmental erosion fee payable on precious based on gross revenues.
3.9 Encumbrances
There are no known encumbrances.
3.10 Permitting
Permitting and permitting conditions are discussed in Chapter 17.9 of this Report. There are no relevant permitting timelines that apply; the operations as envisaged in the LOM plan are either fully permitted, or the processes to obtain permits are well understood and similar permits have been granted to the operations in the past, such as tailings storage facility (TSF) raises.
There are no current material violations or fines as understood in the United States mining regulatory context that apply to the Peñasquito Operations.
| | | | | | | | |
Date: February 2022 | | Page 3-9 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
3.11 Significant Factors and Risks That May Affect Access, Title or Work Programs
To the extent known to the QP, there are no other significant factors and risks that may affect access, title, or the right or ability to perform work on the Project that are not discussed in this Report.
| | | | | | | | |
Date: February 2022 | | Page 3-10 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
4.0 ACCESSIBILITY, CLIMATE, LOCAL RESOURCES, INFRASTRUCTURE, AND PHYSIOGRAPHY
4.1 Physiography
The Project is situated in a wide valley bounded to the north by the Sierra El Mascaron and the south by the Sierra Las Bocas. The prevailing elevation is approximately 1,900 m above sea level. The terrain is generally flat, with some rolling hills.
Vegetation is principally scrub, with cactus and coarse grasses.
With the exception of one small outcrop, the Project area is covered by up to 30 m of alluvium.
4.2 Accessibility
There are two access routes to the operations:
•The first is via a turnoff from Highway 54 onto the State La Pardita road, then onto the Mazapil to Cedros State road. The mine entrance is approximately 10 km after turning northeast onto the Cedros access road;
•The second access is via the Salaverna by-pass road from Highway 54 approximately 25 km south of Concepcion Del Oro. The Salaverna by-pass is a purpose-built gravel road that eliminates steep switchback sections of cobblestone road just west of Concepción Del Oro and passes the town of Mazapil. From Mazapil, this is a well-maintained 12 km gravel road that accesses the mine main gate.
Within the operations area, access is primarily by gravel roads, and foot trails and tracks. The closest rail link is 100 km to the west.
There is a private airport on site and commercial airports in the cities of Saltillo, Zacatecas and Monterrey. Travel from Monterrey/Saltillo is approximately 260 km, about three hours to site. Travel from Zacatecas is approximately 275 km, about 3.5 hours to site.
4.3 Climate
Temperatures range between 30º C and 20º C in the summer and 15º C to 0º C in the winter.
The climate is generally dry with precipitation being limited for the most part to a rainy season in the months of June and July. Annual precipitation for the area is approximately 700 mm, most of which falls in the rainy season. The Project area is affected by tropical storms and hurricanes that result in short-term, high-precipitation events.
Mining operations are conducted year-round.
| | | | | | | | |
Date: February 2022 | | Page 4-1 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
4.4 Infrastructure
A skilled labor force is available in the region and surrounding mining areas of Mexico. Fuel and supplies are sourced from nearby regional centers such as Monterrey, Monclova, Saltillo and Zacatecas. Imports from the United States are sourced via Laredo.
The Peñasquito Operations currently have all infrastructure in place to support mining and processing activities (see also discussions in Chapter 13, Chapter 14, and Chapter 15 of this Report). These Report chapters also discuss water sources, electricity, personnel, and supplies.
| | | | | | | | |
Date: February 2022 | | Page 4-2 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
5.0 HISTORY
5.1 Exploration History
A summary of the exploration and development history of the Peñasquito Operations is provided in Table 5-1.
| | | | | | | | |
Date: February 2022 | | Page 5-1 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Table 5-1: Exploration History
| | | | | | | | |
Year | Operator | Work Undertaken |
1950s | Minera Peñoles | Excavation of a 61 m shaft with a crosscut to the old workings and completion of two drill holes. |
1994–1998 | Minera Kennecott SA de CV (Kennecott) | Discovery of two large mineralized diatreme breccia bodies, the Outcrop (Peñasco) and Azul Breccias. Geochemical surveys. Gravity, CSAMT, reconnaissance IP, scaler IP, airborne radiometrics and magnetics and ground magnetics surveys. 250 RAB drill holes (9,314 m). 72 RC and core drill holes (2 ,209 m): 23 drill holes were drilled in the Peñasco Outcrop Breccia zone, 15 drill holes at Brecha Azul, 13 drill holes at Chile Colorado, and other drill holes scattered outside these zones. |
1998 | Western Copper Holdings Ltd. (Western Copper) | Acquired Project from Kennecott. 9 core holes (3,185 m). 13.4 line km of Tensor CSAMT geophysical survey |
2000 | Minera Hochschild S.A (Hochschild) | 14 core holes (4,601 m); 11 at Chile Colorado. |
2000–2003 | Western Copper | 149 core and RC drill holes (45,916.5 m), and completion of a scoping study. |
2003–2006 | Western Silver Corporation (Western Silver) | Corporate name change from Western Copper to Western Silver. 480 core drill holes, including 13 metallurgical drill holes. Scoping, pre-feasibility and feasibility studies completed. Glamis Gold Ltd. (Glamis Gold) acquired Western Silver in May 2006; Glamis Gold was acquired by Goldcorp Inc. (Goldcorp) in November 2006. |
2012 | CIVIS Inc on behalf of Goldcorp | Topography surface flown on May 25, 2012; flight over the open pit area covered 16 km2 and had a resolution of 10 cm |
2006–2018 | Goldcorp | Updated feasibility study. Mining began in July 2007, the first doré was produced in May 2008, mechanical completion of the first mill/ flotation line (50 kt/d) as achieved in July 2009, and the first concentrates were produced and shipped in October 2009. High-sensitivity aeromagnetic and FALCON Airborne Gravity Gradiometer system flown in 2010; 1,789 line-km of data acquired HELITEM time domain EM helicopter survey flown in 2010–2011; 1,597 line-km of data acquired 1,143 core and RC holes drilled (542,750.49 m) for resource definition, metallurgy, geotechnical evaluation, and condemnation for infrastructure |
2019 | Goldcorp/Newmont Mining Corp. | Corporate merger; Goldcorp Inc. became a fully owned subsidiary of Newmont Mining Corporation and its shares were delisted from stock exchanges; following transaction completion Newmont changed its name to Newmont Goldcorp Corporation. In acknowledgement of Newmont reaching 100 year history the company name was shortened to Newmont Corporation in 2020. |
2019–2020 | Newmont | 119 holes drilled in 2019 (29,999.52 m); |
| | | | | | | | |
Date: February 2022 | | Page 5-2 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
6.0 GEOLOGICAL SETTING, MINERALIZATION, AND DEPOSIT
6.1 Deposit Type
The deposits within the Peñasquito Operations are considered to be examples of breccia pipe deposits developed as a result of intrusion-related hydrothermal activity.
Such deposits are hosted in a tectonic setting of continental magmatism, well-inboard of inferred or recognized convergent plate boundaries, and which commonly contains coeval intrusions of alkalic, metaluminous calc-alkalic, and peraluminous compositions. Preferred host strata include reducing basinal sedimentary or metasedimentary rocks. Deposit locations are often controlled by graben faults and ring complexes related to cauldron development.
Deposits typically consist of mineralized, funnel-shaped, pipe-like, discordant breccia bodies and sheeted fracture zones. Mineralization is hosted by a variety of breccia types, including magmatic-hydrothermal, phreatomagmatic, hydraulic and collapse varieties. Breccia cement consists dominantly of quartz and carbonate (calcite, ankerite, siderite), with specularite and tourmaline at some deposits.
Mineralization characteristically has a low sulfide content (<5 volume %), and contains pyrite, chalcopyrite, sphalerite, galena, and pyrrhotite, with minor molybdenite, bismuthinite, tellurobismuthite and tetrahedrite, which occur either in the matrix or in rock fragments. It is typically silver-rich (gold:silver ratios of 1:10), with associated lead, zinc, copper, ± molybdenum, manganese, bismuth, tellurium, and tungsten), and a lateral (concentric) metal zoning is present at some deposits.
A sericite–quartz–carbonate–pyrite alteration assemblage and variably developed silicification is coincident with mineralized zones, grading outward into propylitic alteration. An early-stage potassium–silicate alteration locally occurs in some deposit areas.
6.2 Regional Geology
The regional geology of the project area is dominated by Mesozoic sedimentary rocks, which are intruded by Tertiary stocks of intermediate composition (granodiorite and quartz monzonite) and overlain by Tertiary terrestrial sediments and Quaternary alluvium.
The Mesozoic sedimentary rocks consist of a >2.5 km thick series of marine sediments deposited during the Jurassic and Cretaceous Periods with a 2,000 m thick sequence of carbonaceous and calcareous turbiditic siltstones and interbedded sandstones underlain by a 1,500–2,000 m thick limestone sequence. Following a period of compressional deformation, uplift, and subsequent erosion, the Mesozoic marine sediments were overlain by the Tertiary Mazapil Conglomerate.
Large granodiorite stocks are interpreted to underlie large portions of the mineralized areas within the Concepción Del Oro District, including the Peñasquito area. Slightly younger quartz–feldspar porphyries, quartz monzonite porphyries, and other feldspar-phyric intrusions occurring as dykes, sills, and stocks cut the sedimentary units. The intrusions are interpreted to have been emplaced from the late Eocene to mid-Oligocene.
| | | | | | | | |
Date: February 2022 | | Page 6-1 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
6.3 Project Geology
The Mesozoic sedimentary rocks of the Mazapil area were folded into east–west arcuate folds during the Laramide orogeny. The end-Laramide extension was accommodated by northwest-, northeast- and north-striking faults, contemporaneous with deposition of Tertiary-aged terrestrial sediments in fault–bounded basins. Tertiary granodiorite, quartz monzonite, and quartz–feldspar porphyry bodies were intruded during this period of extension. Typically, the magmatic bodies were emplaced along anticlines and local syncline axes, and fault intersections.
The current topography reflects the underlying geology, with ranges exposing anticlines of the older Mesozoic rocks, while valleys are filled with alluvium and Tertiary sediments overlying synclinal folds in younger Mesozoic units. Tertiary stocks and batholiths are better exposed in the ranges.
Figure 6-1 is a schematic stratigraphic column for the Project area. Figure 6-2 shows the regional geology.
Two breccia pipes, Peñasco and Brecha Azul, intrude Cretaceous Caracol Formation siltstones in the center of the Mazapil valley. The Peñasco diatreme forms the principal host for known gold–silver–lead–zinc mineralization at the Peñasquito deposit. The Chile Colorado deposit comprises mineralized sedimentary rocks adjacent to the Brecha Azul diatreme.
The breccia pipes are believed to be related to quartz–feldspar porphyry stocks beneath the Peñasquito area. The current bedrock surface is estimated to be a minimum of 50 m (and possibly several hundred meters) below the original paleo-surface when the diatremes were formed.
The brecciated nature of the host rock indicates that the diatremes explosively penetrated the Mesozoic sedimentary units and it is likely that they breached the surface; however, eruption craters and ejecta aprons have since been eroded away.
Alluvium thickness averages 30–50 m at Peñasquito, and this cover obscured the diatremes. There is one small outcrop of breccia near the center of the Peñasco diatreme, rising about 5 m above the valley surface. The single outcrop near the center of the Peñasco pipe contained weak sulfide mineralization along the south and west side of the outcrop, representing the uppermost expression of much larger mineralized zones at depth.
| | | | | | | | |
Date: February 2022 | | Page 6-2 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Figure 6-1: Stratigraphic Column Schematic Sketch
Note: Figure from Rocha-Rocha, 2016.
| | | | | | | | |
Date: February 2022 | | Page 6-3 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Figure 6-2: Regional Geology Map
Note: Figure prepared by Newmont, 2020.
| | | | | | | | |
Date: February 2022 | | Page 6-4 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
6.4 Deposit Descriptions
6.4.1 Overview
Peñasco and Brecha Azul are funnel-shaped breccia pipes, which flare upward, and are filled with brecciated sedimentary and intrusive rocks, cut by intrusive dikes.
The larger diatreme, Peñasco, has a diameter of 900 m by 800 m immediately beneath surface alluvial cover, and diatreme breccias extend to at least 1,000 m below surface. The Brecha Azul diatreme, which lies to the southeast of Peñasco, is about 500 m in diameter immediately below alluvium, and diatreme breccias also extend to at least 1,000 m below surface.
Chile Colorado is a mineralized stockwork located southwest of Brecha Azul, hosted in sediments of the Caracol Formation. It has dimensions of approximately 600 m by 400 m immediately beneath surface alluvial cover, and extends to at least 500 m below the current land surface.
Figure 6-3 is a geology plan of the diatreme area.
Polymetallic mineralization is hosted by the diatreme breccias, intrusive dikes, and surrounding siltstone and sandstone units of the Caracol Formation. The diatreme breccias are broadly classified into three units, in order of occurrence from top to bottom within the breccia column, which are determined by clast composition:
•Sediment-clast breccia;
•Mixed-clast breccia (sedimentary and igneous clasts);
•Intrusive-clast breccia.
Sedimentary rock clasts consist of Caracol Formation siltstone and sandstone. Intrusive rock clasts are dominated by quartz–feldspar porphyry. For the purposes of the geological block model, the sediment-clast breccia (BXS), the sediment-crackle breccia (CkBx), mixed-clast breccia (BXM) and intrusion-clast breccia (BXI) are modeled as separate lithological solids.
A variety of dikes cut the breccia pipes and the immediately adjacent clastic wall-rocks. These dikes display a range of textures from porphyry breccia, to quartz–feldspar and quartz-eye porphyries, to aphanitic micro breccias. For block modelling purposes, the units are simplified into three intrusive lithologies; brecciated intrusive rocks (IBX), felsites and felsic breccias (FI/FBX), and quartz–feldspar porphyry (QFP).
6.4.2 Structure
A complex structural setting generated the structural conditions for magma ascent. When the magma encountered phreatic water, violent explosions and brecciation ensued, giving rise to the phreatomagmatic breccias.
A number of mineralized fault zones have been identified and are included as solids in the block model.
| | | | | | | | |
Date: February 2022 | | Page 6-5 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Figure 6-3: Deposit Geology Map
Note: Figure prepared by Newmont, 2020. Ovb = overburden; KucSlt = Kuc Caracol Formation, siltstone>sandstone; Bxi = sediment, QFP and Fi clasts/milled intrusive mixed hydrothermal breccia; Bxm: mixed sediment>intrusive clasts/milled sediment–intrusive mixed breccia; Bxs: sediment clasts/milled sediment mixed breccias; Ibx: quartz–feldspar porphyry intrusive breccia; Ft: felsite intrusive or breccia; Qfp: quartz–feldspar porphyry;
| | | | | | | | |
Date: February 2022 | | Page 6-6 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
6.4.3 Alteration
Both of the breccia pipes lie within a hydrothermal alteration shell consisting of a proximal sericite–pyrite–quartz (phyllic) alteration (QSP) assemblage, distal sericite–pyrite–quartz– calcite (QSPC) assemblage, and peripheral pyrite–calcite (PC) alteration halo.
There is an inverse relationship between degree of alteration and organic carbon in the Caracol Formation sedimentary rocks, suggesting organic carbon was mobilized or destroyed during alteration.
6.4.4 Mineralization
The diatreme and sediments contain, and are surrounded by, disseminated, veinlet and vein-hosted sulfides and sulfosalts containing base metals, silver, and gold. Mineralization is breccia or dike hosted, mantos, or associated with skarns (Figure 6-4).
Mineralization consists of disseminations, veinlets and veins of various combinations of medium to coarse-grained pyrite, sphalerite, galena, and argentite (Ag2S). Sulfosalts of various compositions are also abundant in places, including bournonite (PbCuSbS3), jamesonite (PbSb2S4), tetrahedrite, polybasite ((Ag,Cu)16(Sb,As)2S11), and pyrargyrite (Ag3SbS3). Stibnite (Sb2S3), rare hessite (AgTe), chalcopyrite, and molybdenite have also been identified. Telluride minerals are the main gold-bearing phase, with electrum and native gold also identified.
Gangue mineralogy includes calcite, sericite, and quartz, with rhodochrosite, fluorite, magnetite, hematite, garnets (grossularite–andradite) and chlorite–epidote. Carbonate is more abundant than quartz as a gangue mineral in veins and veinlets, particularly in the “crackle breccia” that occurs commonly at the diatreme margins.
6.4.4.1 Breccia- and Dike-Hosted Mineralization
Breccia-hosted mineralization is dominated by sulfide disseminations within the matrix with lesser disseminated and veinlet-controlled mineralization in clasts. All breccia types host mineralization, but the favored host is the intrusion-clast breccia. Much of the mineralization within the Peñasco and Brecha Azul pipes lie within the intrusion-clast breccia.
All of the dike varieties are locally mineralized, and they are almost always strongly altered. Mineralization of dikes occurs as breccia matrix fillings, disseminations and minor veinlet stockworks at intrusion margins, and veinlets or veins cutting the more massive dikes.
| | | | | | | | |
Date: February 2022 | | Page 6-7 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Figure 6-4: Deposit Types
Note: Figure prepared by Newmont, 2021.
Mineralized dikes form an important ore host in the Peñasco diatreme but are not as abundant in Brecha Azul.
Mineralization of the Caracol Formation clastic sedimentary units where the units are cut by the diatremes is dominated by sulfide replacement of calcite matrix in sandstone beds and lenses and disseminated sulfides and sulfide clusters in sandstone and siltstones. Cross-cutting vein and veinlet mineralization consists of sulfide and sulfide-calcite fillings.
The Chile Colorado deposit is the largest known sediment-hosted mineralized zone, although others also occur adjacent to Peñasco (e.g., El Sotol), and between the diatremes (e.g., La Palma). El Sotol, located to the west of Peñasco, consists of small horizons mineralized with sulfides and sulfosalts, which are consistent with the stratification of the Caracol Formation.
Reforma is a northwest–southeast oriented vein system consisting of rhodochrosite, sulfides, and sulfosalts that occurs within the Chile Colorado deposit and to the south–southwest of the Peñasco breccia.
| | | | | | | | |
Date: February 2022 | | Page 6-8 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
There is a spatial association between strong QSP alteration and the highest degree of sulfide and sulfosalt mineralization. A halo of generally lower-grade disseminated zinc–lead–gold–silver mineralization lies within the QSPC assemblage surrounding the two breccia pipes.
6.4.4.2 Mantos-Style Mineralization
Mantos-style sulfide replacements of carbonate strata have been identified within and beneath the Caracol Formation adjacent to the diatreme pipes, beneath the clastic-hosted disseminated sulfide zones. They consist of semi-massive to massive sulfide replacements of sub-horizontal limestone beds, as well as structurally-controlled cross-cutting chimney-style, steeply dipping, fracture and breccia zones filled with high sulfide concentrations.
The sulfides are generally dominated by sphalerite and galena, but also contain significant pyrite. Gangue minerals (commonly carbonates) are subordinate in these strata-replacement mantos and cross-cutting chimneys. Stratiform and chimney mantos are characterized by their very high zinc, lead, and silver contents, with variable copper and gold contributions.
6.4.4.3 Skarn Mineralization
Garnet skarn-hosted copper–gold–silver–zinc–lead mineralization (carbonate replacement deposits or CRDs) within dissolution breccias was identified at depth between the Peñasco and Brecha Azul diatremes (Figure 6-4). The mineralized skarns trend northwest–southeast, and have been divided into the following zones:
•CRD Upper zone: a garnet skarn hosted within the Indidura and Cuesta del Cura Formations; x, y, z dimensions of 1,500 x 600 x 450 m;
•CRD Deeps zone: a garnet skarn hosted within the Taraises and La Caja Formations; x, y, z dimensions of 1,300 x 550 x 250 m.
Polymetallic mineralization is hosted by garnet skarn and associated breccias, mainly as chalcopyrite and sphalerite with some gold and silver. Gangue minerals consist of pyrite, calcite, garnet, and magnetite. The garnet skarns are often surrounded by halos of hornfels, especially in siliciclastic units, and/or marble and recrystallized limestone in carbonate units. Deep exploration programs identified quartz feldspar porphyry with strong QSPC and potassic alteration that contains occasional veinlets of quartz with molybdenite, and veins with secondary biotite and magnetite disseminated in the wall rocks.
6.5 QP Comments on “Item 7: Geological Setting and Mineralization”
The QP notes that the knowledge of the deposit setting, lithologies, mineralization style and setting, and structural and alteration controls on mineralization is sufficient to support mineral resource and mineral reserve estimation.
| | | | | | | | |
Date: February 2022 | | Page 6-9 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
7.0 EXPLORATION
7.1 Exploration
A summary of the exploration conducted is provided in Table 7-1. As there is a single small outcrop in the Project area, the primary exploration tools have been geophysics and drilling.
7.1.1 Grids and Surveys
The Project uses UTM NAD27. All data collected prior to establishment of the mining operation were converted to this datum.
Digital terrain data were supplied to Newmont by Eagle Mapping, Vancouver, Canada, from aerial photography completed 13 November 2003. Aerial photography provided a 0.24 m resolution and a vertical and horizontal accuracy of ± 1.0 m. Eagle Mapping also provided an updated topographic surface in 2008.
The last version of digital terrain data was supplied by CIVIS Inc. from photographic flights completed on 25 May 2012. The photography covering the open pit and TSF from the 2012 flights was completed with a resolution of 0.1 m.
7.1.2 Petrology, Mineralogy, and Research Studies
A doctoral thesis was completed on the deposit area in 2016:
•Rocha-Rocha, M., 2016: Metallogenesis of the Penasquito polymetallic deposit: a contribution to the understanding of the magmatic ore system: PhD thesis, University of Nevada, Reno, 338 p.
7.1.3 Qualified Person’s Interpretation of the Exploration Information
The exploration programs completed to date are appropriate to the style of the deposits and prospects. Additional exploration has a likelihood of generating further exploration successes particularly as regional exploration has been limited to date.
7.1.4 Exploration Potential
Significant potential exists at depth below the current operating pits within the current diatreme bodies as well as skarn and mantos mineralization within the surrounding limestone units. Additionally, the surrounding district has relatively little exploration work completed.
Newmont is planning a staged approach at identifying potential targets with geophysical and geochemical surveys, as well as detailed mapping campaigns. This will aid in prioritizing drill targets.
| | | | | | | | |
Date: February 2022 | | Page 7-1 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Table 7-1: Exploration Summary Table
| | | | | |
Type | Comment/Result |
Geological mapping | Mapping within the district surrounding Peñasquito is conducted at 1:5,000 scale. Information mapped includes lithology, and structural measurements. Mapping in the field is mylar using a topography base. It is then digitized using ArcMap software. |
Open pit mapping | Geological mapping at 1:2,000 scale within the pit identifies lithologies and structural elements that are important for geological modeling and geotechnical considerations. |
Geochemical sampling | The only original bedrock exposure at Peñasquito was on a single low hill in the center of what is now known as the Peñasco diatreme. Early explorers in the district collected rock-chip samples from this outcrop. The remainder of the operations area was covered by alluvium, generally 30–40 m thick, and surface sampling was not possible. |
Airborne and ground- based magnetic surveys, airborne radiometric surveys, CSAMT and ground gravity and induced polarization (IP) surveys | The aeromagnetic survey defined an 8 km x 4 km, north–south-trending magnetic high which was approximately centered on the Outcrop (Peñasco) Breccia. The airborne and ground magnetometer surveys suggested the presence of deep-seated granodioritic intrusions and indicated a relationship between mineralization and the underlying plutons. Kennecott identified and defined IP chargeability and resistivity anomalies in the central Peñasquito area and the surveys were instrumental in locating the sulfide stockwork zone at the Chile Colorado. The gravity surveys identified the Brecha Azul diatreme and partially outlined the Peñasco diatreme pipe. |
Airborne magnetic surveys (Goldcorp) | Included coverage of the Peñasquito and Camino Rojo blocks, in Zacatecas State. The first survey utilized a high-sensitivity aeromagnetic and FALCON Airborne Gravity Gradiometer system. This survey was flown on November 11–19, 2010, with a total of 1,789 line-km of data being acquired. The second survey used the HELITEM time domain EM helicopter system and was flown between December 11, 2010 and January 9, 2011 for a total of 1,597 line-km. The two surveys approximately covered the same areas with only modest differences in the positioning of lines. Some anomalies were detected toward the north and east of the Peñasco diatreme, which require exploration follow- up. To date, no exploration has been conducted on these anomalies. |
Structural interpretations | Field evaluations and data collection on the deposit structural setting was conducted in 2017. These data were used to update the structural model used in resource estimation. |
Alteration interpretations | An analytical spectral device was used to collect alteration data from each mining cutback. These data were used to refine the regional alteration model to aid in exploration vectoring, particularly for Caracol Formation sediments. |
| | | | | | | | |
Date: February 2022 | | Page 7-2 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
7.2 Drilling
7.2.1 Overview
7.2.1.1 Drilling on Property
Drilling to December 31, 2021 comprises 1,670 core holes (867,075 m), 52 RC holes with core tails (26,332 m) and 270 RC holes (42,247 m) for a total of 1,992 drill holes (935,638 m). A drill summary table is presented in Table 7-2. Drill collar locations are shown in Figure 7-1. Drilling focused on the exploration and delineation of Chile Colorado, Brecha Azul Zone and Peñasco.
Drilling that supports mineral resource and mineral reserve estimation consists of core and RC drill holes, and totals 1,647 holes for 816,195 m (Table 7-3). The collars of those drill holes used in mineral resource estimation are shown in Figure 7-2.
7.2.1.2 Drilling Excluded For Estimation Purposes
Fourteen drill holes (MHC-01 to MHC-14) completed by Mauricio Hochschild in the current open pit area in 2000 are excluded from estimation, because there are no assay certificates. Short (<40 m ) RC holes were not used for mineral resource estimation.
7.2.2 Drill Methods
Seven drill contractors were used over the Project duration, including Major Drilling Co (core and RC); Adviser Drilling, S.A. de C.V. (core); Layne de Mexico (RC); BDW Drilling (core); KDL Mexico SA de C.V. (core); Boart Longyear Drilling Services-Mexico (core); and Globexplore (RC).
RC drilling was conducted using down-hole hammers and tricone bits, both dry and with water injection. Water flow was rarely high enough to impact the drilling, although water had to be injected to improve sample quality. Some RC drilling was performed as pre-collars for core drill holes. Sample recoveries were not routinely recorded for RC holes.
7.2.3 Logging
Logging of RC drill cuttings and core used standard logging procedures. The level of detail collected varied by drill program and operator, but generally collected lithology, alteration, mineralization, structural features, oxidation description, and vein types.
Core is photographed.
| | | | | | | | |
Date: February 2022 | | Page 7-3 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Table 7-2: Drill Summary Table
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Year | Project Operator | Core | Mixed | RC | Total |
Number of Holes | Drilled Meters | Number of Holes | Drilled Meters | Number of Holes | Drilled Meters | Number of Holes | Drilled Meters |
1994–1997 | Kennecott | 17 | 5,358 | 24 | 13,602 | 31 | 5,075 | 72 | 24,179 |
1998 | Western Copper | 9 | 3,185 | — | — | — | — | 9 | 3,203 |
2000 | Hochschild | 14 | 4,601 | — | — | — | — | 14 | 4,629 |
2002 | Western Copper | 46 | 20,198 | — | — | — | — | 46 | 20,290 |
2003 | 46 | 18,946 | 2 | 865 | 55 | 5,908 | 103 | 25,925 |
2004 | Western Silver | 126 | 59,118 | — | — | — | — | 126 | 59,370 |
2005 | 162 | 98,333 | — | — | — | — | 162 | 98,657 |
2006 | 192 | 110,752 | — | — | — | — | 192 | 111,136 |
2007 | Goldcorp | 195 | 132,366 | — | — | 23 | 4,946 | 218 | 137,748 |
2008 | 58 | 50,643 | — | — | 12 | 3,254 | 70 | 54,037 |
2009 | 47 | 22,182 | — | — | — | — | 47 | 22,276 |
2010 | 37 | 22,175 | — | — | — | — | 37 | 22,249 |
2011 | 21 | 14,032 | — | — | 59 | 2,495 | 80 | 16,687 |
2012 | 85 | 52,991 | — | — | — | — | 85 | 53,161 |
2013 | 72 | 43,342 | — | — | — | — | 72 | 43,486 |
2014 | 129 | 48,825 | — | — | — | — | 129 | 49,083 |
2015 | 103 | 45,626 | — | — | — | — | 103 | 45,832 |
2016 | 119 | 43,754 | — | — | 3 | 99 | 122 | 44,097 |
2017 | 43 | 13,971 | 5 | 2,068 | 35 | 7,116 | 83 | 23,321 |
2018 | 26 | 10,436 | 21 | 9,797 | 50 | 12,633 | 97 | 33,060 |
2019 | Newmont | 18 | 10,162 | — | — | 1 | 271 | 19 | 10,471 |
2020 | 42 | 14,719 | — | — | — | — | 42 | 14,803 |
2021 | 63 | 21,360 | — | — | 1 | 450 | 64 | 21,938 |
Totals | 1,670 | 867,075 | 52 | 26,332 | 270 | 42,247 | 1,992 | 939,638 |
Note: Metreage has been rounded; totals may not sum due to rounding. Mixed = drilling that commenced with RC and was finished using core.
| | | | | | | | |
Date: February 2022 | | Page 7-4 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Figure 7-1: Drill Collar Location Map
| | | | | | | | |
Date: February 2022 | | Page 7-5 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Table 7-3: Drill Summary Table Supporting Mineral Resource Estimates
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Year | Project Operator | Core | Mixed | RC | Total |
Number of Holes | Drilled Meters | Number of Holes | Drilled Meters | Number of Holes | Drilled Meters | Number of Holes | Drilled Meters |
1994–1997 | Kennecott | 17 | 5,358 | 24 | 13,602 | 26 | 4,358 | 67 | 23,452 |
1998 | Western Copper | 9 | 3,185 | — | — | — | — | 9 | 3,203 |
2002 | Western Copper | 46 | 20,198 | — | — | — | — | 46 | 20,290 |
2003 | 46 | 18,946 | 2 | 865 | 46 | 5,008 | 94 | 25,007 |
2004 | Western Silver | 124 | 58,354 | — | — | — | — | 124 | 58,602 |
2005 | 157 | 96,331 | — | — | — | — | 157 | 96,645 |
2006 | 124 | 83,715 | — | — | — | — | 124 | 83,963 |
2007 | Goldcorp | 133 | 108,899 | — | — | 23 | 4,946 | 156 | 114,157 |
2008 | 58 | 50,643 | — | — | 12 | 3,254 | 70 | 54,037 |
2009 | 34 | 16,863 | — | — | — | — | 34 | 16,931 |
2010 | 30 | 18,871 | — | — | — | — | 30 | 18,931 |
2011 | 8 | 8,806 | — | — | 32 | 1,365 | 40 | 10,251 |
2012 | 20 | 26,013 | — | — | — | — | 20 | 26,053 |
2013 | 72 | 43,342 | — | — | — | — | 72 | 43,486 |
2014 | 129 | 48,825 | — | — | — | — | 129 | 49,083 |
2015 | 103 | 45,626 | — | — | — | — | 103 | 45,832 |
2016 | 119 | 43,754 | — | — | 3 | 99 | 122 | 44,097 |
2017 | 37 | 9,626 | 5 | 2,068 | 35 | 7,116 | 77 | 18,964 |
2018 | 26 | 10,436 | 21 | 9,797 | 50 | 12,633 | 97 | 33,060 |
2019 | Newmont | 15 | 9,011 | — | — | 1 | 271 | 16 | 9,314 |
2020 | 41 | 14,419 | — | — | — | — | 41 | 14,501 |
2021 | 19 | 6,298 | — | — | — | — | 19 | 6,336 |
Totals | 1,367 | 747,519 | 52 | 26,332 | 228 | 39,050 | 1,647 | 816,195 |
Note: Metreage has been rounded; totals may not sum due to rounding. Mixed = drilling that commenced with RC and was finished using core.
| | | | | | | | |
Date: February 2022 | | Page 7-6 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Figure 7-2: Drill Collar Location Map for Drilling Supporting Mineral Resource Estimates
Note: Breccia pipes shown as red outlines.
| | | | | | | | |
Date: February 2022 | | Page 7-7 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
7.2.4 Recovery
Core recovery is good, averaging about 97%.
Core drilling typically recovered HQ size core (63.5 mm diameter) from surface, then was reduced to NQ size core (47.6 mm) where ground conditions warranted. Metallurgical drill holes were typically drilled using PQ size core (85 mm).
7.2.5 Collar Surveys
Prior to 2001, drill holes were located using chain-and-compass methods. From 2002 onwards, collar survey was performed by a qualified surveyor. Once mining operations commenced, all surveys have been performed using differential global positioning system (DGPS) instruments. The mine currently uses Trimble R-6 GPS instruments.
7.2.6 Downhole Surveys
Downhole surveys are completed by the drilling contractor using a single shot, through the bit, survey instrument. Drill holes are surveyed on completion of each hole as the drill rods are being pulled from the hole. All drill holes have been downhole surveyed except the 51 Western Silver RC drill holes and 11 of the 17 Kennecott drill holes. Use of gyroscopic survey instruments began in 2012, with measurements taken at 30 m intervals.
7.2.7 Grade Control
Grade control drilling was completed as part of an infill drilling program using core and RC drilling.
7.2.8 Comment on Material Results and Interpretation
Drill hole spacing is generally on 50 m sections in the main deposits, with tighter spacing for infill drilling within the Peñasco pit. Drilling on 400 m spaced sections was completed in the condemnation zones and drill spacing is wider again in the areas outside the conceptual pit outlines used to constrain mineral resources. Drilling covers an area approximately 11 km east–west by 7 km north–south with the majority of drill holes concentrated in an area 2.1 km east–west by 2.8 km north–south.
Drilling is normally perpendicular to the strike of the mineralization. Depending on the dip of the drill hole, and the dip of the mineralization, drill intercept widths are typically greater than true widths.
Drill orientations are generally appropriate for the mineralization style, and have been drilled at orientations that are optimal for the orientation of mineralization for the bulk of the deposit areas (Figure 7-3 and Figure 7-4).
Sampling is representative of the grades in the deposit area, reflecting areas of higher and lower grades.
| | | | | | | | |
Date: February 2022 | | Page 7-8 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Figure 7-3: Example Drill Section
Note: Figure prepared by Newmont, 2020.
| | | | | | | | |
Date: February 2022 | | Page 7-9 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Figure 7-4: Example Drill Section
Note: Figure prepared by Newmont, 2020.
| | | | | | | | |
Date: February 2022 | | Page 7-10 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
No material factors were identified with the data collection from the drill programs that could affect mineral resource or mineral reserve estimation.
7.3 Hydrogeology
Pit dewatering is undertaken using 12 vertical, in-pit dewatering wells, drilled to 1,000–1,050 m depths. The holes are 444.5 mm (17.5”) in diameter, have 305 mm (12”) steel casing and screen over the entire hole (i.e., to total depth), and are installed with electrical submersible pumps controlled by variable frequency drives.
Contingency measures have included sump and surface pumping to mitigate the presence of groundwater at the pit bottom (pit lake and pit sumps).
7.3.1 Sampling Methods and Laboratory Determinations
Mining operations staff perform water level monitoring on observation and pumping wells by means of numerous vibrating wire piezometers and pump pressure transducers.
Water monitoring sampling is conducted by the environmental department, on wells within the pit, and external wells, as well as monitoring wells upstream and downstream of the TSF and the heap leach pad facilities. Groundwater in the vicinity of the TSF and heap leach pad facilities is analyzed for environmental compliance purposes, and analysis is performed for standard water chemistry parameters on the pumping wells.
Collection of hydrological data is done by site staff, and typically includes airlift testing during RC drilling and well development, water level measurements and pumping tests from dewatering wells.
7.3.2 Groundwater Models
There are currently two groundwater models for pit dewatering that cover the two open pits. The first model was developed by Newfields in 2019, and the second, updated numerical model was prepared by Itasca in 2020.
A regional-scale aquifer model was constructed by Geomega in 2018. Work is ongoing to develop numerical models for external well fields under the supervision of the environmental department.
7.3.3 Comment on Results
A combination of historical and current hydrological data, together with operating experience, govern the pit dewatering plan.
Monitoring wells are used to track potential environmental non-compliance in the vicinity of the TSF and heap leach pad facilities; to date, no significant issues have been identified by the monitoring programs.
| | | | | | | | |
Date: February 2022 | | Page 7-11 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
7.4 Geotechnical
Geotechnical drilling was completed in support of infrastructure locations and in support of pit designs.
7.4.1 Sampling Methods and Laboratory Determinations
The geotechnical model for the Peñasquito Operations was defined by geotechnical drilling and logging, laboratory testwork, rock mass classification, structural analysis and stability modeling. Completed testwork included:
•Degree of alteration;
•Point load index testing;
•Unconfined compressive strength testing;
•Triaxial compressive strength testing;
•Brazilian tensile strength testing;
•Determination of Hoek-Brown material constant “mi”;
•Shear strength of discontinuities;
•Rock mass strength;
•Shear strength anisotropy.
Rock mass rating (RMR) and Q-Barton parameters were logged for rock mass strength evaluations. Unconfined compressive strength testing was conducted by Call & Nicholas, Inc. (CNI; 2009–2015) and SRK Consulting Inc. (SRK, 2016). Additional tests included uniaxial and triaxial compressive strength testing. Rock strength index determinations from core logging resulted in a 90% ratio match or with slightly lower estimates than the unconfined compression strength determinations from the laboratory testing, indicating that core logging estimates are suitable and slightly conservative for design purposes.
Estimates of hardness, based on ISRM (1981), were collected on a run-by-run basis by Golder Associates (Golder; 2005), SRK (2016b), and Piteau Associates (Piteau; 2017, 2018).
Values for the Hoek-Brown material constant “mi” that were used by Piteau (2018) for pit designs, were derived using results from triaxial strength, unconfined compressive strength, and Brazilian tensile strength testing results. Discontinuity shear strengths were based on the results of historical laboratory direct shear testing.
CNI, Golder, SRK, and Piteau are independent third-party consultants who have specialist geotechnical testing facilities. Testing followed standard protocols for geotechnical testwork. There is no system for accreditation of geotechnical laboratories.
| | | | | | | | |
Date: February 2022 | | Page 7-12 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
7.4.2 Models
A continuum model for rock mass disturbance for phases 6D, 8, and 9 of the open pits was developed to account for the effects of blasting and stress relief on rock mass strength based on the results of yield percentage versus depth relationships from a preliminary Universal Distinct Element Code software model.
Assessment of fault, bedding shear, joint, and bedding structural sets defining shear strength anisotropy and two-dimensional (2D) anisotropic limit equilibrium stability analyses was conducted using SLIDE2 2018 software on cross sections through the Phase 9 of the open pit, incorporating the combined influence of adverse structural orientations and potential for shearing through intact rock mass; and development of bench, inter-ramp, and overall slope design criteria for the Phase 9 mine plan.
7.4.3 Monitoring
There are five displacement monitoring radars on site, three of which monitor the Peñasco pit, and two in the Chile Colorado pit. There are four robotic total station instruments, three at the Peñasco pit, and one at the Chile Colorado pit. The radars are used to monitor for issues and known problems, including displacement, old failures, bench-scale bedding plane movements, wedge slides, and material spills.
Blast vibration is monitored using Instantel blast monitoring equipment.
A geotechnical events register is maintained, and incidences are logged. There is also a record of the zones of instability zones in each pit, with information such as location, key structural data, lithologies, and event type noted.
7.4.4 Comment on Results
A combination of historical and current geotechnical data, together with mining experience, are used to established pit slope designs and procedures that all benches must follow.
Analytical methods are used to evaluate structural behavior of the rock mass.
Third-party consultants were retained to provide the recommended pit slope guidelines.
These data and mining experience support the geotechnical operating considerations used in the mine plans in Chapter 13 of this Report.
| | | | | | | | |
Date: February 2022 | | Page 7-13 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
8.0 SAMPLE PREPARATION, ANALYSES, AND SECURITY
8.1 Sampling Methods
8.1.1 RC
RC drill holes were sampled at intervals of 2 m. The drill cuttings were split at the drill into several portions of 12 kg or less. A handful of rock chips from each sample interval was collected and logged by experienced onsite geologists. Data from the drill logs were entered digitally into ASCII files, then uploaded to the Project database.
8.1.2 Core
For all core holes, the standard sample interval is 2 m. The only departures from this are the splitting of a 2 m interval into two portions at the overburden/bedrock contact, and in areas of low recovery, where multiples of 2 m are used to ensure that after splitting, a minimum 1 kg sample is obtained. In most cases this occurs in the upper portions of drill holes where significant weathering has occurred. Samples are marked on the inside of the boxes by a technician for the entire hole. For condemnation drill holes, one sample of 2 m was taken every 20 m unless geological inspection dictated otherwise.
Core is halved using saws. Half of the cut core is placed in the plastic sample bag and half remains in the boxes which are stored on shelves in several large, secure warehouses.
QA/QC materials are inserted by exploration staff in the dispatch portion of the sampling area. The bags are then tied with string and placed in rice bags, three per bag, the sample numbers are written on the rice bags, and they are stacked for shipment.
8.1.3 Grade Control
Blast hole samples for submission to the on-site laboratory are collected by the Mine Geology staff using a hand held rotary drill to collect cuttings on a pre-defined pattern from the cone of cuttings. For blast holes where there is poor recovery, a larger number of sampling points is used. Samplers try to maintain an 8 kg sample size.
8.2 Sample Security Methods
Sample security was not generally practiced at Peñasquito during the exploration drilling programs, due to the remote nature of the site. Sample security relied upon the fact that the samples were always attended or locked at the sample dispatch facility. Sample collection and transportation have always been undertaken by company or laboratory personnel using company vehicles.
Current practice is for drill core to be collected from the drill rig by Newmont employees and delivered to the secure exploration facility in the town of Mazapil, 12 km east of the mine where it is logged and sampled. Sample shipments are picked up once a week by a truck from ALS Global and taken to one of their sample preparation facilities. Formerly, samples were sent to
| | | | | | | | |
Date: February 2022 | | Page 8-1 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Guadalajara but currently they are prepared in Zacatecas. After preparation samples are sent by air to the ALS Global analytical facility in North Vancouver, B.C for analysis.
Chain-of-custody procedures consist of filling out sample submittal forms that are sent to the laboratory with sample shipments to make certain that all samples were received by the laboratory.
After sampling, core is stored in secure facilities in Mazapil for future reference. Some core is stored on steel shelves within the secure exploration facility, and some core is stored in secure warehouses a short distance away. As far as is practicable, core is stored in numeric sequence by drill hole number and depth.
Sample rejects and pulps are returned by ALS Global to Newmont’s core shack in Mazapil for storage. Coarse rejects in plastic bags are stored in cardboard boxes on steel racks in a separate locked building and are labelled and stored by sample number. Weathering has deteriorated the integrity of individual rejects and pulps from earlier drill programs.
8.3 Density Determinations
A total of 1,229 specific gravity (SG) measurements were collected in 2008 on drill core. An additional 127 bulk density measurements are available from Dawson Metallurgical Laboratories Inc. Utah (Dawson). SG data were then used to assign average bulk specific gravity values by lithology.
Since 2011, a standard procedure was implemented, whereby a density sample consisting of un-split core (usually HQ), 20 to 30 cm in length, is taken every 50 m from core holes. Core is wax coated, and the density determined using the standard water immersion method. After testing the sample is returned to the core box.
The density database currently contains about 6,947 determinations.
8.4 Analytical and Test Laboratories
Sample preparation and analytical laboratories used for primary analyses during the exploration programs on the Project include ALS Chemex, and Bondar Clegg (absorbed into ALS Chemex in 2001). The laboratories are currently operated by ALS Global.
ALS Chemex was responsible for sample preparation throughout the Western Copper, Western Silver, and Goldcorp exploration and infill drilling phases. For much of the operations history the sample preparation facilities in Guadalajara were used; however, samples are currently prepared at the ALS Global facility in Zacatecas. The sample preparation facilities are not accredited. All prepared samples (pulps) are dispatched to the Vancouver, Canada laboratory facility for analysis. At the time the early work was performed ALS Chemex was ISO-9000 accredited for analysis; the laboratory is currently ISO-17025 certified. ALS Global is independent of Newmont.
Early check assays (umpire) analyses were performed by Acme Laboratories in Vancouver, which at the time held ISO-9000 accreditation. SGS Mexico (SGS) was used for more recent check assay analyses. SGS holds ISO/IEC 17025:2005 certification. Both Acme and SGS are independent of Newmont.
The on-site mine laboratory is not certified and is not independent of Newmont.
| | | | | | | | |
Date: February 2022 | | Page 8-2 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
8.5 Sample Preparation
Sample preparation methods for the various major sampling types is summarized in Table 8-1.
8.6 Analysis
Table 8-2 summarizes the analytical methods used, which can vary by sample type and laboratory.
Blast hole samples are analyzed by standard fire assay for gold and silver using a standard fire assay with an atomic absorption spectrometry (AA) finish. If the assay prill weighs more than 5 mg, a second assay is run with a gravimetric finish. Analysis for copper, lead, zinc, arsenic, antimony and cadmium are performed on a 1 g sample that is subject to a multi-acid digestion and determination by AA.
Systematic assays of blast hole samples for organic carbon began in June 2016, by the LECO method with hydrochloric acid digestion.
8.7 Quality Assurance and Quality Control
Goldcorp, Newmont Goldcorp, and Newmont maintained a quality assurance and quality control (QA/QC) program for the Peñasquito Operations. This included regular submissions of blank, duplicate and standard reference materials (standards) in samples sent for analysis from both exploration and mine geology. Results were regularly monitored.
8.7.1 Goldcorp (2006–2017)
During the 2006–2017 Goldcorp programs, two primary field blanks were used with Goldcorp drill samples, sourced from local materials. In general, these blanks have performed well in monitoring for contamination; however, both blanks have a number of unexplained failures that suggest the material used is occasionally weakly mineralized. One standard set was generated by Metcon Research of Tucson, Arizona on core from Peñasquito, and a second set of standards were prepared by SGS in Durango from Peñasquito open pit material. Results for the Metcon SRMs generally displayed very good assay accuracy, although there were a number of weak biases relative to the expected values, mainly weak high biases. The SGS SRMs also generally showed good assay precision but similarly show weak biases, mainly for lead and zinc. Such biases relative to expected values are not unusual. Submission of half-core duplicates indicated good assay precision.
| | | | | | | | |
Date: February 2022 | | Page 8-3 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Table 8-1: Sample Preparation Procedures
| | | | | | | | | | | |
Laboratory | Duration | Sample Type | Preparation Procedure |
ALS Chemex (Western Copper) | 1998, 2002–2003 | RC and core | Crush to ≥70% passing 10 mesh (2.0 mm); pulverize to ≥85% passing 200 mesh (75 µm) |
ALS Chemex/ ALS Global | Pre-2003 | RC and core | Crush to ≥75% passing 10 mesh (2.0 mm); pulverize to ≥95% passing 150 mesh (105 µm) |
2003–date | RC and core | Crush to ≥70% passing 10 mesh (2.0 mm); pulverizing to ≥85% passing 200 mesh (75 µm) |
On-site laboratory | 2010–date | Grade control | Crush to ≥70% passing 10 mesh (2.0 mm); pulverize to ≥85% passing 200 mesh (75 µm) |
Table 8-2: Analytical Methods
| | | | | | | | |
Laboratory | Element | Method |
ALS Chemex/ ALS Global | Gold | FA-AA23; fire assay on 30 g sample with AA finish. Much of data previously used ME-GRA21; fire assay with gravimetric finish on a one-assay-ton (30 g) charge. For assays >10 ppm ME- GRA21 is still used. AA became the primary analytical finish in 2010. |
Silver | ME-ICP41; 0.5 g charge digested in aqua regia acid and analyzed via ICP-AES; for over limits, method ME-GRA21 is used, a fire assay with a gravimetric finish on a one-assay-ton charge (30 g) |
Zinc | ME-ICP41; and for over limits method Zn-OG46 is used which is 0.4 g charge digested in aqua regia acid and analyzed by ICP-AES or inductively coupled plasma – mass spectrometer ICP- MS). |
Lead | ME-ECP41; 0.5 g charge digested in aqua regia acid and analyzed with ICP-AES; for over limits method Pb-OG46 is used |
Acme | Gold | Group 6; fire assay with an inductively coupled plasma emissions spectrometer (ICPES) analytical finish on a one-assay-ton charge (30 g). |
Silver | Group D; 0.5 g charge digested in aqua regia acid and analyzed with and ICP-ES; and for over limits Ag-AA46, which is 0.4-g charge digested in aqua regia acid and analyzed using ICP-ES. |
Zinc | Group D; 1-g charge digested in aqua regia acid and analyzed with ICP-ES; Ag-AA46 for over limits |
Lead | Group D; 0.5 g charge digested in aqua regia acid and analyzed with ICP-ES; Ag-AA46 for over limits |
SGS | Gold | GE FAA313; 30 g fire assay with AA finish |
Silver | ICP-14B; ICP-AES. For assays>100g/t GO FAG313; 30 g fire assay with AA finish |
Zinc | ICP14B; 0.5 g charge digested in aqua regia and analyzed with ICP-AES. ICP90q for over limits). |
Lead | ICP14B; 0.5 g charge digested in aqua regia and analyzed with ICP-AES. ICP90q for over limits). |
Note: FA = fire assay, AA = atomic absorption, ICP-AES = inductively coupled plasma atomic emission spectroscopy, ICP-OES = inductively coupled plasma optical emission spectroscopy.
| | | | | | | | |
Date: February 2022 | | Page 8-4 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
8.7.2 Newmont Goldcorp; Newmont (2017 to date)
In 2019, the insertion rates of standards was changed to 1/84 to ensure one standard was included into a fusion batch of 84 crucibles in the laboratory. Additionally, pulp and prep duplicates were introduced to monitor sample preparation performance by the laboratory. In 2021, the insertion rate of standards was changed to 1/50, because the previous insertion rate did not consider the internal laboratory QC samples. The current insertion rate of QC samples followed at Peñasquito for drill holes is:
•Standard (SGS Durango): 1/50 samples;
•Field duplicate: 1/50 samples;
•Blank: 1/100 samples;
•Pulp duplicate: 1/100 samples;
•Prep duplicate: 1/100 samples.
8.7.3 Check Assays
At total of 652 pulps from the 2012–2013 drilling programs were submitted to SGS in 2014 for check assay. Results show negligible bias for gold and silver while SGS displayed weak low biases for lead and zinc relative to ALS Chemex.
8.7.4 Grade Control
Grade control sample submissions during the Goldcorp programs included field duplicates from blast holes and blanks. Assay precision as determined by the duplicates was good. The blank submitted was a local overburden that was determined in mid-2015 to have anomalous values for gold, silver, lead and zinc. A new source of blank material was identified from an area about 50 km from the mine site and is in use.
Check assays on grade control samples are sent regularly to ALS Global. ALS Global does display weak to moderate high biases relative to the mine laboratory for gold, silver, lead and zinc, mainly at higher grades for the latter two. Additional multi-element standards are being acquired for use in grade control.
After the Goldcorp merger, the ore control department adapted its QA/QC program to follow the Newmont guidelines. These consisted of the following QA/QC sample types and insertion rates:
•Field duplicates at an insertion rate of 1/50 (second sample from a blast cone);
•Preparation duplicates at an insertion rate of 1/30 (second sample from crusher at laboratory);
•Pulp duplicates at an insertion rate of 1/30 (second sample from pulverizer at laboratory);
•Standards at a frequency to obtain at least one standard per assay batch. Standards should be purchased/made to allow evaluation of laboratory performance at a range of values and especially near critical cutoff grades;
•Coarse (preferred) blanks at an insertion rate of at least 1/100.
| | | | | | | | |
Date: February 2022 | | Page 8-5 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Random laboratory visits, including site or project geologists, must be conducted and documented. The minimum requirement is annually.
Monthly meetings are conducted to discuss performance and the current work in process. Results to the Report date indicate good assay precision.
8.7.5 Mine Laboratory
The on-site laboratory uses pulp blanks in its fire assay runs and has included quartz washes in sample preparation in the past. The laboratory currently passes a blank for each batch received in the crushing and every 27 samples or less cleans the pulverizer. Results from the pulp blanks indicates no problems with contamination. Standards purchased from Rocklabs are inserted once every 30 sample assay run and show good assay accuracy. Multi-element standards were added to the program in 2016, and current results reflect good performance from the laboratory. The laboratory prepares reject duplicates every 20 samples and regularly runs pulp replicate analyses. Both show good assay precision.
The mine laboratory regularly sends pulps for check assay to ALS Global with results displaying similar high biases by ALS Global to those displayed by the grade control check assays.
The Geology department also regularly sends pulps for check assay to ALS Global. Results from ALS Global are similar to the original assays from the mine laboratory for the majority of samples that have been check-assayed.
8.8 Database
Database entry procedures historically consisted of entering data from paper logging forms into Excel files before being imported into acQuire. Geological data from early drill programs were entered into spreadsheets in a single pass. It is not known what kind of data base was used prior to 2009.
All drill data from 2007 to July 2013 was entered from paper logging forms into Excel files before being imported into acQuire. Since July 2013, logging and recording of other drill hole data by geologists and technicians has been directly into acQuire on laptop computers, with the data subsequently imported into the main database. Assays received electronically from the laboratories are imported directly into the database. Analytical certificates received since 2010 have been stored in the database and were validated via the acQuire software.
Data were verified on entry to the database by means of built-in program triggers within the mining software. Checks were performed on surveys, collar co-ordinates, lithology data, and assay data.
In February 2021, the Peñasquito exploration drill database was migrated from acQuire into the Newmont Global Exploration Database structure (GED). Newmont’s in-house applications are used to load drilling relevant data such as collar, downhole surveys, geotechnical and geological logging, samples and assays. The procedures used to manage the database are the same as used by the company globally.
Paper records are retained on file. Exploration data are appropriately stored on a mine server, and data are regularly backed up by the mine information technology (IT) department.
| | | | | | | | |
Date: February 2022 | | Page 8-6 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
8.9 Qualified Person’s Opinion on Sample Preparation, Security, and Analytical Procedures
The sample preparation, analysis, quality control, and security procedures used by the Peñasquito Operations have changed over time to meet evolving industry practices. Practices at the time the information was collected were industry-standard.
The Qualified Person is of the opinion that the sample preparation, analysis, quality control, and security procedures are sufficient to provide reliable data to support estimation of mineral resources and mineral reserves:
•Drill collar data are typically verified prior to data entry into the database, by checking the drilled collar position against the planned collar position;
•The sampling methods are acceptable, meet industry-standard practice, and are adequate for mineral resource and mineral reserves estimation and mine planning purposes;
•The density determination procedure is consistent with industry-standard procedures. A check of the density values for lithologies across the different deposits indicates that there are no major variations in the density results;
•The quality of the analytical data is reliable, and that sample preparation, analysis, and security are generally performed in accordance with exploration best practices and industry standards;
•Newmont has a QA/QC program comprising blank, standard and duplicate samples. Newmont’s QA/QC submission rate meets industry-accepted standards of insertion rates. The QA/QC data support that there are no material issues with analytical precision or accuracy;
•Verification is performed on all digitally-collected data on upload to the main database, and includes checks on surveys, collar co-ordinates, lithology, and assay data. The checks are appropriate, and consistent with industry standards.
| | | | | | | | |
Date: February 2022 | | Page 8-7 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
9.0 DATA VERIFICATION
9.1 Internal Data Verification
9.1.1 Data Validation
Validation checks are performed by operations personnel on data used to support estimation comprise checks on surveys, collar coordinates, lithology data (cross-checking from photographs), and assay data. Errors noted are rectified in the database.
Three different databases are in use at the mine site:
•Mapinfo dataset; compiled historic assay tables in Excel, with lithology data;
•Resource dataset; pre-2010 resource database with appended 2011 data manipulated in Excel from acQuire exports;
•acQuire database;
•Current GED database.
A review of the datasets indicated that there were some extremely high copper values especially in historic WC series drilling, and that the 2013 acQuire database might not contain a full set of historic assay records due to data loading errors during the original implementation of the acQuire system in 2008–2009. Goldcorp was provided with permission to download from the assay laboratory, the original assays from the Western Copper and Western Silver programs. Subsequently, the 2012 and 2011 drill data sets were reviewed for completeness of historic drill information, and any missing data were entered into acQuire. Comments were added to the collar information as required. All other legacy (pre-Goldcorp) data were carefully reviewed and verified by Goldcorp personnel. The revised historic assay data in the database are now considered to reflect the information in the downloaded assay certificates, and are suitable for use for exploration targeting and construction of geological models.
The following are undertaken in support of database quality:
•Inspection of all laboratories are undertaken on a regular basis to ensure that they are well maintained and that all procedures are being properly followed. Deficiencies or concerns are reported to the laboratory manager;
•QA/QC data is monitored closely and detailed reports are prepared on a monthly basis. Assay data needs to be approved before import in to the database;
•Drill data including collar co-ordinates, down hole surveys, lithology data, and assay data are typically verified prior to mineral resource and mineral reserve estimation by running program checks in both database and resource modelling software packages.
| | | | | | | | |
Date: February 2022 | | Page 9-1 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
9.1.2 Reviews and Audits
Newmont has a policy of peer reviews of all aspects of the mineral resource estimates. Those reviews include evaluations of the database, geological models and the mineral resource estimates. The most recent reviews were performed in 2019 and 2020.
The Reserve and Resource Review or “3R” reviews examined:
•Geology and geostatistics: ore control, exploration development, data collection/management, QA/QC and geological modeling;
•Geotechnical and hydrological: pit slope design and execution, tailings management, heap leaching, and waste rock facilities;
•Processing: metallurgical accounting; business plan inputs; risk and opportunity management;
•Mine engineering: equipment productivity, costs, unitized costs for pit optimization and cut-off, Whittle inputs, pit optimization, pit designs, cut-off grades, reserves test.
No significant or critical issues were noted as a result of the 3R audits. A number of recommendations were put forward to address potential gaps and inconsistencies between legacy Goldcorp practices and Newmont’s current standards.
9.1.3 Mineral Resource and Mineral Reserve Estimates
Newmont established a system of “layered responsibility” for documenting the information supporting the mineral resource and mineral reserve estimates, describing the methods used, and ensuring the validity of the estimates. The concept of a system of “layered responsibility” is that individuals at each level within the organization assume responsibility, through a sign-off or certification process, for the work relating to preparation of mineral resource and mineral reserve estimates that they are most actively involved in. Mineral reserve and mineral resource estimates are prepared and certified by QPs at the mine site level, and are subsequently reviewed by QPs in the Newmont-designated “region”, and finally by corporate QPs based in Newmont’s Denver head office.
9.1.4 Reconciliation
Newmont staff perform a number of internal studies and reports in support of mineral resource and mineral reserve estimation. These include reconciliation studies, mineability and dilution evaluations, investigations of grade discrepancies between model assumptions and probe data, drill hole density evaluations, long-range plan reviews, and mining studies to meet internal financing criteria for project advancement.
| | | | | | | | |
Date: February 2022 | | Page 9-2 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
9.1.5 Subject Matter Expert Reviews
The QP requested that information, conclusions, and recommendations presented in the body of this Report be reviewed by Newmont experts or experts retained by Newmont in each discipline area as a further level of data verification.
Peer reviewers were requested to cross-check all numerical data, flag any data omissions or errors, review the manner in which the data were reported in the technical report summary, check the interpretations arising from the data as presented in the report, and were asked to review that the QP’s opinions stated as required in certain Report chapters were supported by the data and by Newmont’s future intentions and Project planning.
Feedback from the subject matter experts was incorporated into the Report as required.
9.2 External Data Verification
A number of third-party consultants have performed external data reviews, as summarized in Table 12-1.
These external reviews were undertaken in support of acquisitions, support of feasibility-level studies, and in support of technical reports, producing independent assessments of the database quality. No significant problems with the database, sampling protocols, flowsheets, check analysis program, or data storage were noted.
9.3 Data Verification by Qualified Person
The QP performed a site visit in October 2021 (refer to Chapter 2.4). Observations made during the visit, in conjunction with discussions with site-based technical staff also support the geological interpretations, and analytical and database quality. The QP’s personal inspection supports the use of the data in mineral resource and mineral reserve estimation, and in mine planning.
The QP’s site visit in 2021 was part of Newmont’s Reserve and Resource Review (3R) process, which requires internal reviews of all sites on a rotating basis. The 2021 3R found that Peñasquito generally meets all of Newmont’s internal standards and guidelines regarding mineral resource and mineral reserve estimation.
The QP receives and reviews monthly reconciliation reports from the mine site. These reports include the industry standard reconciliation factors for tonnage, grade and metal; F1 (reserve model compared to ore control model), F2 (mine delivered compared to mill received) and F3 (F1 x F2) along with other measures such as compliance of actual production to mine plan and polygon mining accuracy. The reconciliation factors are recorded monthly and reported in a quarterly control document. Through the review of these reconciliation factors the QP is able to ascertain the quality and accuracy of the data and its suitability for use in the assumptions underlying the mineral resource and mineral reserve estimates.
| | | | | | | | |
Date: February 2022 | | Page 9-3 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Table 9-1: External Data Reviews
| | | | | | | | |
Consultant | Year | Comment |
SNC Lavalin | 2003 | Database audit, check assay review, independent witness sampling. |
Independent Mining Consultants | 2005 | Database review for feasibility purposes, check assay review, review of variances between drill campaigns. |
Mine Development Associates | 2007 | Review of check assay data. |
P&E Mining Consultants | 2008 | QA/QC review. |
Hamilton | 2014 | QA/QC review. |
9.4 QP Comments on “Item 12: Data Verification”
Data that were verified on upload to the database, checked using the layered responsibility protocols, and reviewed by subject matter experts are acceptable for use in mineral resource and mineral reserve estimation.
| | | | | | | | |
Date: February 2022 | | Page 9-4 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
10.0 MINERAL PROCESSING AND METALLURGICAL TESTING
10.1 Test Laboratories
Metallurgical testwork was conducted by a number of laboratories prior to and during early operations. These included: Hazen Research, Golden Colorado, USA; Instituto de Metalurgia, UASLP, San Luis Potosi, México; FLSmidth Knelson, British Columbia, Canada; ALS Metallurgy Kamloops, British Columbia; Kemetco, Richmond, British Columbia; Surface Science Western, London, Ontario; AuTec, Vancouver, British Columbia; Blue Coast Research, Parksville, British Columbia; XPS, Falconbridge, Ontario; and Met-Solve, Langley, British Columbia. All of these laboratories were and are independent. Additional metallurgical tests were performed at the Minera Peñasquito Metallurgical Laboratory, which is not independent.
Current testwork is being performed at Newmont’s internal Malozemoff Technical Facility which is not independent and by independent laboratories Alfa Laval, Coatex, Solvay, Patterson and Cooke and Microanalytical.
There is no international standard of accreditation provided for metallurgical testing laboratories or metallurgical testing techniques.
10.2 Metallurgical Testwork
Metallurgical testwork included: mineralogy; open and closed-circuit flotation; lead–copper separation flotation; pyrite flotation; bottle and column cyanide leaching; flotation kinetics and cell design parameters, flowsheet definition, and leach response with regrind size, slurry density, leaching time, reagent consumption values, and organic carbon effects; gravity-recoverable gold; hardness characterization (SMC, breakage parameter, Bond ball mill work index, drop weight index, rod work index, unconfined compressive strength, semi-autogenous grind (SAG) power index); and batch and pilot plant tests.
These test programs were sufficient to establish the optimal processing routes for the oxide and sulfide ores, performed on mineralization that was typical of the deposits. The results obtained supported estimation of recovery factors for the various ore types.
Since the early start-up of operations, metallurgical testing was performed on a daily basis for all ores that were feed to the mill. These daily tests were aimed to capture the expected performance of the ore in the sulfide plant to determine in advance any change in the reagent scheme or in the impurity levels into the final concentrates.
Historically, this resulted in identification of a number of different ore types. Current understanding of ore characterization and variability has simplified forecast metallurgical recovery classification to sediment and diatreme ores and the relative organic carbon content.
| | | | | | | | |
Date: February 2022 | | Page 10-1 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
10.3 Recovery Estimates
The mineralogical complexity of the Peñasquito ores makes the development of recovery models difficult as eight elements (gold, silver, lead, zinc, copper, iron, arsenic, and antimony) are tracked through the process. Recovery models need to be sufficiently robust to allow for changes in mineralogy and plant operations, while providing reasonable predictions of concentrate quality and tonnage.
The previous recovery model used for the Peñasquito Operations was integrated in 2017. An update was completed in 2021. The sulfide recovery model (2021RM) currently used at the Peñasquito Operations was built using operational information from 2017–2020, which included additional organic carbon data. The model was integrated into the Peñasquito resource block model and into the budgeting and forecasting exercises during May and June of 2021 for the 2022 Peñasquito production budget (BP22). The pyrite leach plant recovery model was built on operational information from 2019–April 2020 and integrated into mine planning during mid-2020.
Forecast average life-of-mine recoveries for the sulfide plant are:
•Gold: 69%;
•Silver: 87%;
•Lead: 73%;
•Zinc: 81%.
The last ore placed onto the oxide heap leach pad was in August 2019 and grades were depleted finalizing production in August, 2020. The oxide heap leach is currently only being recirculated with water and closure studies are under development.
10.4 Metallurgical Variability
Samples selected for metallurgical testing during feasibility and development studies were representative of the various types and styles of mineralization within the deposit. Samples were selected from a range of locations within the deposit zones. Sufficient samples were taken so that tests were performed on sufficient sample mass.
10.5 Deleterious Elements
The mineralogy at Peñasquito is diverse. Galena and sphalerite are the main payable base metals minerals, with a host of complex sulfosalts (including tennantite and tetrahedrite) also reporting to the concentrates. These sulfosalts can carry varying amounts of deleterious elements such as arsenic, antimony, copper and mercury. Copper can also be considered as a commodity as it is paid by certain customers. At the date of this Report, the processing plant, in particular the flotation portion of the circuit, does not separate the copper-bearing minerals from the lead minerals, so when present the sulfosalts report (primarily) to the lead concentrate. There is no direct effect of deleterious elements on the recovery of precious and base metals
The marketing contracts are structured to allow for small percentages of these deleterious elements to be incorporated into the final product, with any exceedances then incurring nominal
| | | | | | | | |
Date: February 2022 | | Page 10-2 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
penalties. Historically, due to the relatively small proportion of concentrate that has high levels of deleterious elements, the marketing group was able to sufficiently blend the majority of the deleterious elements such that little or no financial impact has resulted.
Within the metallurgical models used at Peñasquito, copper recovery to lead concentrate varies from 40–80%, with 10–20% copper recovery into zinc concentrate. Due to the close mineralogical association, arsenic and antimony recovery to concentrate is based on a relationship to the copper in the concentrate. The future impact of the deleterious elements is thus highly dependent on the lead–copper ratio in ores.
Mercury is not included in the metallurgical models as it is not included in the mine plan. One small area of the mine (located within a narrow fault zone that is hosted in sedimentary rock in the southwest of the pit) was defined as containing above-average mercury grades. Due to its limited size, blending should be sufficient to minimize the impact of mercury from this area on concentrate quality.
Organic carbon has also been recognized as a deleterious element affecting the recovery of gold and the operational cost in the process plant. The carbon pre-flotation process was built to allow for removal of liberated organic carbon ahead of lead and zinc flotation and the pyrite leach plant, so that those process steps could operate in a similar fashion to operation with low-carbon ores.
10.6 Qualified Person’s Opinion on Data Adequacy
In the opinion of the QP, the metallurgical test work and reconciliation and production data support the declaration of mineral resources and mineral reserves:
•The metallurgical test work completed on the Project was appropriate for optimizing processing conditions and routes for proper process operation;
•Tests were performed on samples that are considered to be representative for the deposit and its mineralogy;
•Recovery factors estimated are based on appropriate metallurgical testwork, plant operational information, and are appropriate to the mineralization types and the selected process route;
•The plant will produce variations in recovery due to the day-to-day changes in ore type or combinations of ore type being processed. These variations are expected to trend to the forecast recovery value for monthly or longer reporting periods.
The QP notes:
•The new recovery models consider the effect of organic carbon throughout the process. These new models are robust and should provide an accurate estimation of production and recoveries;
•The 2021 throughput model is a power-based model that integrates feed material lithology into recovery calculations, and therefore considers the effects of the properties of the various ores on the process.
| | | | | | | | |
Date: February 2022 | | Page 10-3 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
11.0 MINERAL RESOURCE ESTIMATES
11.1 Introduction
The database supporting resource estimation contains core drilling information from numerous drilling campaigns beginning in the 1990s through to the database close-out date of 10 June 2021. Geological interpretations were compiled using Leapfrog software. MineSight was used for compositing and grade interpolation. The block size selected was 15 x 15 x 15 m.
11.2 Geological Models
Models constructed included lithology, alteration, structure, oxidation, grade shells, north–south domains, fault domains, and organic carbon.
11.3 Exploratory Data Analysis
The raw drilling data and composites were coded by lithology, alteration, structural, north–south domains and fault domains, and statistically analyzed using summary statistics, log histograms, and log probability plots to determine domain selection for the resource estimation.
Contact boundary analysis was used to determine whether domain contacts would be treated as soft, firm or hard during estimation.
11.4 Density Assignment
Density was tabulated by a combination of lithology, alteration and zone. Density values may be decreased based on the presence of oxides and/or faulting within the block being estimated.
11.5 Grade Capping/Outlier Restrictions
Outlier grades were investigated using cumulative probability plots and histograms of the raw assay grades by estimation domain. Grade caps were applied to raw assay data prior to compositing. The selected cut-off varied by domain and was selected at around the 99th to 99.9th percentile for all interpolated metals.
Caps were applied by domain and could vary. Depending on domain, gold, silver, lead, zinc, copper, arsenic, antimony and sulfur grades could be capped. No capping was applied to organic carbon or iron values.
An isotropic search distance that ranged from about 50–100 m was used to constrain the extrapolation of high grades (outlier restriction) for most elements and domains.
11.6 Composites
Composites were created down each hole at 5 m fixed intervals. In the models that use grade domains, composites were constructed to honor grade–domain contacts, that is, composites end at each grade–domain contact, and start again after it. Composites <2 m in length were discarded.
| | | | | | | | |
Date: February 2022 | | Page 11-1 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
11.7 Variography
Multi-directional variograms (correlograms) were developed using Sage software for gold, silver, lead, and zinc for each domain to determine grade continuity of these elements.
Most variograms are modelled with two exponential models and the nugget set using the down-hole variogram or an omni-directional variogram with a short lag spacing.
11.8 Estimation/Interpolation Methods
Ordinary kriging was used to interpolate blocks, using two passes for all elements other than iron. A range of inputs were used by domain. Iron was estimated using inverse distance weighting to the second power (ID2).
11.9 Block Model Validation
Model validation processes included:
•Visual inspection of the results on plan and section compared to the composites data and blastholes data;
•Comparison of the estimate against previous model (separately for each metal) and nearest-neighbor (NN) distributions;
•Comparison of the estimates against ore-control estimation distributions using grade–tonnage curves;
•Analysis of grade profiles by easting, northing and elevation using swath plots;
The check showed that the models were acceptable for use in mineral resources and mineral reserve estimation.
11.10 Classification of Mineral Resources
11.10.1 Mineral Resource Confidence Classification
Mineral resources at Peñasquito are classified using criteria based primarily on drilling spacing and a minimum number of drill holes informing each estimated block:
•Measured mineral resources require an average drill spacing distance of 27.5 m and at least three drill holes;
•Indicated mineral resources require an average drill spacing of 50 m and at least three drill holes;
•Inferred mineral resources require an average drill spacing of 200 m and at least three drill holes;
•All blocks within the Overburden domain were classified as Inferred.
Smoothing was undertaken to eliminate isolated blocks of one class surrounded by blocks of a different class.
| | | | | | | | |
Date: February 2022 | | Page 11-2 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
11.10.2 Uncertainties Considered During Confidence Classification
Following the analysis in Chapter 11.10.1 that classified the mineral resource estimates into the measured, indicated and inferred confidence categories, uncertainties regarding sampling and drilling methods, data processing and handling, geological modelling, and estimation were incorporated into the classifications assigned.
The areas with the most uncertainty were assigned to the inferred category, and the areas with fewest uncertainties (stockpiles) were classified as measured.
11.11 Reasonable Prospects of Eventual Economic Extraction
11.11.1 Input Assumptions
For each resource estimate, an initial assessment was undertaken that assessed likely infrastructure, mining, and process plant requirements; mining methods; process recoveries and throughputs; environmental, permitting and social considerations relating to the proposed mining and processing methods, and proposed waste disposal, and technical and economic considerations in support of an assessment of reasonable prospects of economic extraction.
Cut-off grades will vary over the life of an open pit, due to variations in capital and operating costs, mine and mill performance, metal prices, exchange rates, and potentially, individual deposit geological and grade characteristics.
Mineral resources were constrained within a designed pit shell that is based on a Lerchs–Grossmann pit shell that used the parameter assumptions listed in Table 11-1.
11.11.2 Commodity Price
Commodity prices used in resource estimation are based on long-term analyst and bank forecasts, supplemented with research by Newmont’s internal specialists. An explanation of the derivation of the commodity prices is provided in Chapter 16.2. The estimated timeframe used for the price forecasts is the 10-year LOM that supports the mineral reserve estimates.
11.11.3 Cut-off
Mineral resources are reported using cut-offs that are determined by the process route. The cut-off is based on generating positive net smelter return (NSR) on a block-by-block basis, applying all revenue and associated costs. The incremental NSR cost used for mill feed material is US$12.49/t, and includes all process operating, administrative and sustaining capital costs. Other factors considered include product freight to market costs, smelter costs (including penalties), and royalties.
| | | | | | | | |
Date: February 2022 | | Page 11-3 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Table 11-1: Conceptual Pit Parameter Input Assumptions
| | | | | | | | | | | |
| Item | Units | Value |
Bench face angles | Range from/to | º | 35.9–50.5 |
Metallurgical recoveries (average, LOM) | Gold | % | 69 |
Silver | % | 87 |
Lead | % | 73 |
Zinc | % | 81 |
Costs | Mining cost, Penasquito, Chile Colorado | US$/t | 1.94; 1.65 |
Mill processing cost | US$/t | 10.25 |
Operational support G&A | US$/t | 2.31 |
Rehandle cost | US$/t | 0.48 |
Sustaining capital allocation (TSF construction cost) | US$/t | 1.68 |
Sustaining capital allocation (other) | US$/t | 0.41 |
Saavi Energia electricity | US$/t | 0.52 |
Commodity prices | Gold | US$/oz | 1,400 |
Silver | US$/oz | 23 |
Lead | US$/lb | 1.10 |
Zinc | US$/lb | 1.40 |
Exchange rate | Mexican Peso/US Dollar | | 19.5 |
11.11.4 QP Statement
The QP is of the opinion that any issues that arise in relation to relevant technical and economic factors likely to influence the prospect of economic extraction can be resolved with further work.
The mineral resource estimates are performed for a deposit that is in a well-documented geological setting; the Peñasquito deposits have seen nearly 14 years of active open pit operations conducted by Newmont and other parties; Newmont is familiar with the economic parameters required for successful operations in the Peñasquito area; and Newmont has a history of being able to obtain and maintain permits, and the social license to operate, and meet environmental standards in the Peñasquito area.
11.12 Mineral Resource Statement
Mineral resources are reported using the mineral resource definitions set out in SK1300 on a 100% basis.
The estimates are current as at December 31, 2021.
The reference point for the estimates is in situ.
Mineral resources are reported exclusive of those mineral resources converted to mineral reserves.
The mineral resource estimates for the Peñasquito Operations are provided as follows:
•Gold: Table 11-2 (measured and indicated); Table 11-3 (inferred);
•Silver: Table 11-4 (measured and indicated); Table 11-5 (inferred);
•Lead: Table 11-6 (measured and indicated); Table 11-7 (inferred);
| | | | | | | | |
Date: February 2022 | | Page 11-4 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
•Zinc: Table 11-8 (measured and indicated); Table 11-9 (inferred).
11.13 Uncertainties (Factors) That May Affect the Mineral Resource Estimate
Areas of uncertainty that may materially impact the mineral resource estimates include:
•Changes to long-term commodity price assumptions;
•Changes in local interpretations of mineralization geometry and continuity of mineralized zones;
•Changes to geological shape and continuity assumptions;
•Changes to metallurgical recovery assumptions;
•Changes to the operating cut-off assumptions for mill feed or stockpile feed;
•Changes to the input assumptions used to derive the conceptual open pit outlines used to constrain the estimate;
•Changes to the cut-off grades used to constrain the estimates;
•Variations in geotechnical, hydrogeological and mining assumptions;
•Changes to governmental regulations;
•Changes to environmental assessments;
•Changes to environmental, permitting and social license assumptions
| | | | | | | | |
Date: February 2022 | | Page 11-5 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Table 11-2: Measured and Indicated Mineral Resource Statement (Gold)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Measured Mineral Resources | Indicated Mineral Resources | Measured and Indicated Mineral Resources |
Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) |
Peñasco | 11,400 | 0.33 | 120 | 65,500 | 0.34 | 720 | 76,800 | 0.34 | 840 |
Chile Colorado | 20,100 | 0.24 | 160 | 111,100 | 0.22 | 780 | 131,200 | 0.22 | 930 |
Open Pit Sub-Total | 31,400 | 0.27 | 280 | 176,600 | 0.27 | 1,500 | 208,000 | 0.27 | 1,780 |
Total Peñasquito | 31,400 | 0.27 | 280 | 176,600 | 0.27 | 1,500 | 208,000 | 0.27 | 1,780 |
Table 11-3: Inferred Mineral Resource Statement (Gold)
| | | | | | | | | | | |
Area | Inferred Mineral Resources |
Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) |
Peñasco | 43,100 | 0.5 | 760 |
Chile Colorado | 46,700 | 0.3 | 400 |
Open Pit Sub-Total | 89,800 | 0.4 | 1,160 |
Total Peñasquito | 89,800 | 0.4 | 1,160 |
Table 11-4: Measured and Indicated Mineral Resource Statement (Silver)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Measured Mineral Resources | Indicated Mineral Resources | Measured and Indicated Mineral Resources |
Tonnage (x 1,000 t) | Grade (g/t Ag) | Cont. Silver (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Ag) | Cont. Silver (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Ag) | Cont. Silver (x 1,000 oz) |
Peñasco | 11,400 | 21.60 | 7,890 | 65,500 | 21.79 | 45,850 | 76,800 | 21.76 | 53,740 |
Chile Colorado | 20,100 | 28.04 | 18,100 | 111,100 | 29.05 | 103,780 | 131,200 | 28.90 | 121,870 |
Open Pit Sub-Total | 31,400 | 25.71 | 25,990 | 176,600 | 26.36 | 149,620 | 208,000 | 26.26 | 175,610 |
Total Peñasquito | 31,400 | 25.71 | 25,990 | 176,600 | 26.36 | 149,620 | 208,000 | 26.26 | 175,610 |
| | | | | | | | |
Date: February 2022 | | Page 11-6 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Table 11-5: Inferred Mineral Resource Statement (Silver)
| | | | | | | | | | | |
Area | Inferred Mineral Resources |
Tonnage (x 1,000 t) | Grade (g/t Ag) | Cont. Silver (x 1,000 oz) |
Peñasco | 43,100 | 28.4 | 39,440 |
Chile Colorado | 46,700 | 27.6 | 41,400 |
Open Pit Sub-Total | 89,800 | 28.0 | 80,840 |
Total Peñasquito | 89,800 | 28.0 | 80,840 |
Table 11-6: Measured and Indicated Mineral Resource Statement (Lead)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Measured Mineral Resources | Indicated Mineral Resources | Measured and Indicated Mineral Resources |
Tonnage (x 1,000 t) | Grade (% Pb) | Contained Lead (M lbs) | Tonnage (x 1,000 t) | Grade (% Pb) | Contained Lead (M lbs) | Tonnage (x 1,000 t) | Grade (% Pb) | Contained Lead (M lbs) |
Peñasco | 11,400 | 0.24 | 60 | 65,500 | 0.23 | 330 | 76,800 | 0.23 | 390 |
Chile Colorado | 20,100 | 0.33 | 140 | 111,100 | 0.28 | 690 | 131,200 | 0.29 | 830 |
Open Pit Sub-Total | 31,400 | 0.29 | 200 | 176,600 | 0.26 | 1,020 | 208,000 | 0.27 | 1,230 |
Total Peñasquito | 31,400 | 0.29 | 200 | 176,600 | 0.26 | 1,020 | 208,000 | 0.27 | 1,230 |
Table 11-7: Inferred Mineral Resource Statement (Lead)
| | | | | | | | | | | |
Area | Inferred Mineral Resources |
Tonnage (x 1,000 t) | Grade (% Pb) | Contained Lead (M lbs) |
Peñasco | 43,100 | 0.2 | 220 |
Chile Colorado | 46,700 | 0.3 | 260 |
Open Pit Sub-Total | 89,800 | 0.2 | 480 |
Total Peñasquito | 89,800 | 0.2 | 480 |
| | | | | | | | |
Date: February 2022 | | Page 11-7 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Table 11-8: Measured and Indicated Mineral Resource Statement (Zinc)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Measured Mineral Resources | Indicated Mineral Resources | Measured and Indicated Mineral Resources |
Tonnage (x 1,000 t) | Grade (% Zn) | Contained Zinc (M lbs) | Tonnage (x 1,000 t) | Grade (% Zn) | Contained Zinc (M lbs) | Tonnage (x 1,000 t) | Grade (% Zn) | Contained Zinc (M lbs) |
Peñasco | 11,400 | 0.46 | 110 | 65,500 | 0.47 | 670 | 76,800 | 0.46 | 790 |
Chile Colorado | 20,100 | 0.78 | 350 | 111,100 | 0.64 | 1,560 | 131,200 | 0.66 | 1,910 |
Open Pit Sub-Total | 31,400 | 0.66 | 460 | 176,600 | 0.57 | 2,230 | 208,000 | 0.59 | 2,690 |
Total Peñasquito | 31,400 | 0.66 | 460 | 176,600 | 0.57 | 2,230 | 208,000 | 0.59 | 2,690 |
Table 11-9: Inferred Mineral Resource Statement (Zinc)
| | | | | | | | | | | |
Area | Inferred Mineral Resources |
Tonnage (x 1,000 t) | Grade (% Zn) | Contained Zinc (M lbs) |
Peñasco | 43,100 | 0.5 | 460 |
Chile Colorado | 46,700 | 0.6 | 610 |
Open Pit Sub-Total | 89,800 | 0.5 | 1,070 |
Total Peñasquito | 89,800 | 0.5 | 1,070 |
Notes to accompany mineral resource tables:
1.Mineral resources are current as at December 31, 2021. Mineral resources are reported using the definitions in SK1300 on a 100% basis. The Qualified Person responsible for the estimate is Mr. Donald Doe, RM SME, Group Executive, Reserves, a Newmont employee.
2.The reference point for the mineral resources is in situ.
3.Mineral resources are reported exclusive of mineral reserves. Mineral resources that are not mineral reserves do not have demonstrated economic viability.
4.Mineral resources that are potentially amenable to open pit mining methods are constrained within a designed pit . Parameters used are included in Table 11-1
5.Tonnages are metric tonnes rounded to the nearest 100,000. Gold and silver grades re rounded to the nearest 0.01 grams per tonne. Lead and zinc grade is reported as a %. Gold and silver ounces and lead and zinc pounds are estimates of metal contained in tonnages and do not include allowances for processing losses. Contained (cont.) gold and silver ounces are reported as troy ounces, rounded to the nearest 10,000. Lead and zinc are reported as pounds.
6.Rounding of tonnes and contained metal content as required by reporting guidelines may result in apparent differences between tonnes, grade and contained metal content. Due to rounding, some cells may show a zero (“0”).
7.Totals may not sum due to rounding.
| | | | | | | | |
Date: February 2022 | | Page 11-8 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
12.0 MINERAL RESERVE ESTIMATES
12.1 Introduction
Measured and indicated mineral resources were converted to mineral reserves. All Inferred blocks were classified as waste. Mineral reserves include mineralization within the Peñasco and Chile Colorado open pits, and stockpiled material. All Inferred blocks are classified as waste in the cashflow analysis that supports mineral reserve estimation.
12.2 Pit Optimization
Whittle pit optimization through the commercially-available EK15 software program was used to perform a Lerchs–Grossmann optimization. The reserve pit designs were full crest and toe detailed designs with final ramps.
For mineral reserves, Newmont applies a time discount factor to the dollar value block model that is generated in the Lerchs–Grossmann pit-limit analysis, to account for the fact that a pit will be mined over a period of years, and that the cost of waste stripping in the early years must bear the cost of the time value of money. In some deposits, where mineralization is uniformly distributed throughout the pit, or where the pit is shallow, discounting has little effect on the economic pit limit.
Pit discounting is accomplished by running the pit-limit “dollar” model through a program that discounts the dollar model values at a compound rate based on the depth of the block. In this manner, discounting is applied to future costs as well as future revenues, to represent the fact that mining proceeds from the top down within a phase.
Optimization work involved floating cones at a series of gold prices. The generated nested pit shells were evaluated using the mineral reserve prices of US$1,200/oz for gold, US$20/oz for silver, US$0.90/lb for lead, and US$1.15/lb for zinc and an 8% discount rate. The pit shells with the highest NPV were selected for detailed engineering design work.
A realistic schedule was developed in order to determine the optimal pit shell for each deposit; schedule inputs include the minimum mining width, and vertical rate of advance, mining rate and mining sequence.
12.3 Optimization Inputs and Assumptions
The pit slope, metallurgical recovery, and commodity price optimization inputs are summarized in Table 12-1.
| | | | | | | | |
Date: February 2022 | | Page 12-1 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Table 12-1: Optimisation Input Parameters
| | | | | | | | | | | |
| Item | Units | Value |
Overall slope angles | Range from/to | º | 39–75 35.9–50.5 |
Metallurgical recoveries (average, LOM) | Gold | % | 69 |
Silver | % | 867 |
Lead | % | 73 |
Zinc | % | 81 |
Costs | Mining cost, Penasquito, Chile Colorado | US$/t | 2.04; 2.11 |
Mill processing cost | US$/t | 10.25 |
Operational support G&A | US$/t | 2.31 |
Rehandle cost | US$/t | 0.48 |
Sustaining capital allocation (TSF construction cost) | US$/t | 1.11 |
Sustaining capital allocation (other) | US$/t | 0.41 |
Saavi Energia electricity | US$/t | 0.52 |
Commodity prices | Gold | US$/oz | 1,200 |
Silver | US$/oz | 20 |
Lead | US$/lb | 0.90 |
Zinc | US$/lb | 1.15 |
Exchange rate | Mexican Peso/US Dollar | | 19.5 |
Mining considerations included:
•Operational considerations with respect to active mining area interaction and ramp usage from the exit from the pit bottom;
•Ramp connections, ramp placement, and ramp exits;
•Minimum mining width of 45 m;
•The existing topography and target final pit limits.
Pit designs are full crest and toe detailed designs with final ramps based on the selected optimum pit shells. Pit designs honor geotechnical guidelines.
Newmont updates its LOM plan each year in preparation for the business plan. All aspects of the plan, including pit stage design and sequencing, cut-off optimization and WRSF and stockpiling strategies are reviewed.
The process plant processes higher-grade ores delivered from the mine at an elevated cut-off. The ore between the elevated cut-off and the marginal cut-off is stockpiled for later processing at the end of the mine life.
Most of the ore will be directly fed to the process plant; however, some re-handle is required. Direct feeding to the crusher is constrained by where the ore is located in the open pit and the crusher availability. Some higher-grade ore is stockpiled and fed back to the crusher when required. Approximately 36,000 t/d of feed is re-handle material from the stockpiles.
The mine plan is based on a 36 Mt/a mill throughput. The schedule was developed at an NSR cut-off of US$14.61/t, incorporating the processing cost, metallurgical recovery, incremental ore mining costs, process sustaining capital and tailings dam related rehabilitation costs. The net revenue calculation assumes a gold price of US$1,200/oz silver price of US$20/oz, lead price of
| | | | | | | | |
Date: February 2022 | | Page 12-2 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
US$0.90/lb and a zinc price of US$1.15/lb. The assumed exchange rate for mineral reserves was 19.5 Mexican pesos per US$. Mineral reserves are reported above an NSR cut-off of US$14.61/t.
12.4 Ore Loss and Dilution
The block models were constructed to include the expected dilution and ore loss based on mining methods, bench height and other factors. The current mine and process reconciliation support this assumption.
12.5 Stockpiles
Stockpile estimates were based on mine dispatch data; the grade comes from closely-spaced blasthole sampling and tonnage sourced from truck factors. The stockpile volumes are typically updated based on monthly surveys. The average grade of the stockpiles is adjusted based on the material balance to and from the stockpile.
12.6 Commodity Prices
Mineral reserves that will be mined using open pit mining methods are reported within a mine design. Commodity prices used in mineral reserve estimation are based on long-term analyst and bank forecasts, supplemented with research by Newmont’s internal specialists. The estimated timeframe used for the price forecasts is the 10-year LOM that supports the mineral reserve estimates.
12.7 Mineral Reserves Statement
Mineral reserves are reported using the mineral reserve definitions set out in SK1300 on a 100% basis.
Mineral reserves are current as at December 31, 2021.
The reference point for the mineral reserve estimate is as delivered to the process facilities.
The mineral reserve estimates for the Peñasquito Operations are provided as follows:
•Gold: Table 12-2;
•Silver: Table 12-3;
•Lead: Table 12-4;
•Zinc: Table 12-5.
Tonnages in the tables are metric tonnes.
| | | | | | | | |
Date: February 2022 | | Page 12-3 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Table 12-2: Mineral Reserves Statement (Gold)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Proven Mineral Reserves | Probable Mineral Reserves | Proven and Probable Mineral Reserves |
Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) |
Peñasco | 74,100 | 0.69 | 1,650 | 171,100 | 0.60 | 3,300 | 245,300 | 0.63 | 4,940 |
Chile Colorado | 33,000 | 0.46 | 490 | 48,000 | 0.40 | 620 | 81,000 | 0.43 | 1,110 |
Open Pit Sub-Total | 107,200 | 0.62 | 2,140 | 219,100 | 0.56 | 3,920 | 326,300 | 0.58 | 6,050 |
Stockpile Sub-Total | 7,800 | 0.43 | 110 | 27,900 | 0.19 | 170 | 35,700 | 0.24 | 280 |
Total Peñasquito | 115,000 | 0.61 | 2,250 | 247,000 | 0.51 | 4,080 | 362,000 | 0.54 | 6,330 |
Table 12-3: Mineral Reserves Statement (Silver)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Proven Mineral Reserves | Probable Mineral Reserves | Proven and Probable Mineral Reserves |
| Tonnage (x 1,000 t) | Grade (g/t Ag) | Cont. Silver (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Ag) | Cont. Silver (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Ag) | Cont. Silver (x 1,000 oz) |
Peñasco | 74,100 | 38.65 | 92,130 | 171,100 | 32.32 | 177,850 | 245,300 | 34.23 | 269,970 |
Chile Colorado | 33,000 | 39.09 | 41,520 | 48,000 | 34.29 | 52,920 | 81,000 | 36.25 | 94,430 |
Open Pit Sub-Total | 107,200 | 38.79 | 133,650 | 219,100 | 32.75 | 230,760 | 326,300 | 34.73 | 364,410 |
Stockpile Sub-Total | 7,800 | 31.10 | 7,810 | 27,900 | 24.15 | 21,670 | 35,700 | 25.67 | 29,470 |
Total Peñasquito | 115,000 | 38.26 | 141,460 | 247,000 | 31.78 | 252,430 | 362,000 | 33.84 | 393,880 |
| | | | | | | | |
Date: February 2022 | | Page 12-4 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Table 12-4: Mineral Reserves Statement (Lead)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Proven Mineral Reserves | Probable Mineral Reserves | Proven and Probable Mineral Reserves |
Tonnage (x 1,000 t) | Grade (% Pb) | Contained Lead (M lbs) | Tonnage (x 1,000 t) | Grade (% Pb) | Contained Lead (M lbs) | Tonnage (x 1,000 t) | Grade (% Pb) | Contained Lead (M lbs) |
Peñasco | 74,100 | 0.41 | 660 | 171,100 | 0.30 | 1,140 | 245,300 | 0.33 | 1,800 |
Chile Colorado | 33,000 | 0.30 | 220 | 48,000 | 0.28 | 300 | 81,000 | 0.29 | 520 |
Open Pit Sub-Total | 107,200 | 0.37 | 880 | 219,100 | 0.30 | 1,440 | 326,300 | 0.32 | 2,320 |
Stockpile Sub-Total | 7,800 | 0.34 | 60 | 27,900 | 0.32 | 200 | 35,700 | 0.33 | 260 |
Total Peñasquito | 115,000 | 0.37 | 940 | 247,000 | 0.30 | 1,640 | 362,000 | 0.32 | 2,580 |
Table 12-5: Mineral Reserves Statement (Zinc)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Proven Mineral Reserves | Probable Mineral Reserves | Proven and Probable Mineral Reserves |
| Tonnage (x 1,000 t) | Grade (% Zn) | Contained Zinc (M lbs) | Tonnage (x 1,000 t) | Grade (% Zn) | Contained Zinc (M lbs) | Tonnage (x 1,000 t) | Grade (% Zn) | Contained Zinc (M lbs) |
Peñasco | 74,100 | 0.92 | 1,510 | 171,100 | 0.70 | 2,630 | 245,300 | 0.77 | 4,140 |
Chile Colorado | 33,000 | 1.04 | 750 | 48,000 | 0.92 | 970 | 81,000 | 0.96 | 1,720 |
Open Pit Sub-Total | 107,200 | 0.96 | 2,260 | 219,100 | 0.74 | 3,600 | 326,300 | 0.81 | 5,860 |
Stockpile Sub-Total | 7,800 | 0.67 | 120 | 27,900 | 0.45 | 280 | 35,700 | 0.50 | 390 |
Total Peñasquito | 115,000 | 0.94 | 2,380 | 247,000 | 0.71 | 3,870 | 362,000 | 0.78 | 6,250 |
Notes to accompany mineral reserve tables:
1.Mineral reserves current as at December 31, 2021. Mineral reserves are reported using the definitions in SK1300 on a 100% basis. he Qualified Person responsible for the estimate is Mr. Donald Doe, RM SME, Group Executive, Reserves, a Newmont employee.
2.The reference point for the mineral reserves is the point of delivery to the process plant.
3.Mineral reserves are confined within open pit designs. Parameters used are summarized in Table 12-1.
4.Tonnages are metric tonnes rounded to the nearest 100,000. Gold and silver grades re rounded to the nearest 0.01 grams per tonne. Lead and zinc grade is reported as a %. Gold and silver ounces and lead and zinc pounds are estimates of metal contained in tonnages and do not include allowances for processing losses. Contained (cont.) gold and silver ounces are reported as troy ounces, rounded to the nearest 10,000. Lead and zinc are reported as pounds.
5.Rounding of tonnes and contained metal content as required by reporting guidelines may result in apparent differences between tonnes, grade and contained metal content. Due to rounding, some cells may show a zero (“0”).
6.Totals may not sum due to rounding.
| | | | | | | | |
Date: February 2022 | | Page 12-5 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
12.8 Uncertainties (Factors) That May Affect the Mineral Reserve Estimate
Areas of uncertainty that may materially impact all of the mineral reserve estimates include:
•Changes to long-term metal price and exchange rate assumptions;
•Changes to metallurgical recovery assumptions;
•Changes to the input assumptions used to derive the mineable shapes applicable to the open pit mining methods used to constrain the estimates;
•Changes to the forecast dilution and mining recovery assumptions;
•Changes to the cut-off values applied to the estimates;
•Variations in geotechnical (including seismicity), hydrogeological and mining method assumptions;
•Changes to governmental regulations, including taxation regimes;
•Changes to environmental, permitting and social license assumptions.
| | | | | | | | |
Date: February 2022 | | Page 12-6 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
13.0 MINING METHODS
13.1 Introduction
Open pit mining is conducted using conventional techniques and an Owner-operated conventional truck and shovel fleet. Currently, two open pits, Peñasco and Chile Colorado are being mined.
13.2 Geotechnical Considerations
The geotechnical model is based on information from geotechnical drilling and logging, laboratory test work, rock mass classification, structural analysis and stability modeling. A total of 12 geotechnical units are defined for planning purposes, using a combination of lithology, mineralization, alteration and laboratory test results. Overall pit slope angles vary by sector within both Peñasco and Chile Colorado open pits, and are based on the recommendations from third-party consultants and Newmont personnel.
The overall designs are based around 15 m mining bench and 30 m double bench intervals. Some inter-ramp heights extend to 45 m and have 5 m-wide step-outs to control potential slope instabilities. Designs take into account haulage ramp positioning, safety berms, and other geotechnical features required to maintain safe inter-ramp slope angles.
Wall control monitoring is supported by five monitoring radars and two robotic total stations installed, covering the total area of the pits.
Designs are reviewed for geotechnical compliance and maximum slope height, global angles and interaction with infrastructure or roads. As mining operations progress in the pit, additional geotechnical drilling and stability analysis will continue to be conducted to support optimization of the geotechnical parameters in the LOM designs.
13.3 Hydrogeological Considerations
A combination of Newmont staff and external consultants have developed the pit water management program, completed surface water studies, and estimated the life- of-mine site water balance. Management of water inflows to date have been appropriate, and no hydrological issues that could impact mining operations have been encountered.
Water levels are maintained at least 30 m below the active mining elevation (bench) to ensure efficient production and safe access. The current pumping system consists of seven wells surrounding the current Peñasco open pit. Six of the wells are located inside the pit and the remaining well is located outside the current mining boundary, but within the overall tenement holdings.
The mine dewatering wells are drilled to 17” (43 cm) diameter and then a 10” (25.4 cm) casing is installed with gravel pack between the casing and drill hole to provide a conductive flow path. The average depth of the wells is 850 m. All wells are vertical and contain downhole submersible pumps which discharge into high-density polyethylene (HDPE) conveyance lines for collection in the fresh water pond. Well control is maintained via a fiber-optic line that is directly connected to the plant control room.
| | | | | | | | |
Date: February 2022 | | Page 13-1 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
The pit area water levels are monitored through a network of piezometer wells, located both within the pit and surrounding it, for accurate water level measurement and reporting.
13.4 Operations
A mine schedule was developed using the commercially-available Deswik Scheduler software package. In this schedule, the Peñasquito pit has four remaining stages (Phases 6 to 9), and will be excavated to a total depth of 780 m. The Chile Colorado pit has one remaining stage (Phase 2), and will reach 461 m ultimate depth. A final pit layout plan showing the pit phases is provided in Figure 13-1.
The remaining mine life is 10 years, with the last year, 2031, being a partial year. The open pit operations will progress at a nominal annual mining rate of 193 Mt/a until the end of 2023, subsequently decreasing to a nominal mining rate of 144 Mt/a until the end of 2027. The LOM plan assumes a nominal rate of 36 Mt/a milling until 2031.
Operations use a standard drill-and-blast, truck-and-shovel configuration. The ramp design comprises two traffic lanes, safety berms and ditches. Ramp gradients are established at 10%. Haul road width assumptions include berm security of 8 m of width. The height of the safety berm is generally about ⅔ of the diameter of tire of the largest vehicle travelling on the road.
An ore stockpiling strategy is practiced. The mine plan considers the value of the blocks mined on a continuous basis combined with the expected concentrates quality. From time to time ore material with a lower NSR value will be stockpiled to bring forward the processing of higher-value ore earlier in the LOM.
In some instances, the ore is segregated into stockpiles of known composition to allow for blending known quantities of material at the stockpile as required by the mill/customer.
Stockpiling at Peñasquito also allows for forward planning for ore quality to ensure optimal mill performance and consistent gold production match, within the normal bounds of expected variability within the mine plan.
13.5 Blasting and Explosives
Drill patterns range from 8.00 m x 9.00 m in overburden to 5.00 m x 5.50 m in sulfide ore.
Blasting is carried out primarily with conventional ANFO explosives, supplied by an explosives contractor. Appropriate powder factors are used to match ore, waste, and overburden types.
| | | | | | | | |
Date: February 2022 | | Page 13-2 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Figure 13-1: Final Pit Layout Plan
Note: Figure prepared by Newmont, 2021.
| | | | | | | | |
Date: February 2022 | | Page 13-3 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
13.6 Grade Control
Ore control is undertaken 24 hrs/7 days a week in 12-hour shifts. Samples are taken from blast holes and sent to the mine laboratory. Once results are available, the database is updated, and interpolation is carried out in the ore control model. Ore and waste boundaries are delineated using an NSR cut-off of US$14.61/t. The material is released according to ore type and the stockpile destination is defined. Field geologists supervise the digging accuracy, and ensure that the correct materials are sent to the correct destination. Ore control staff also provides guidance on material specifications, and provide input so that short-term blending plans are complied with.
13.7 Production Schedule
The LOM forecast production schedule is provided in Table 13-1.
13.8 Mining Equipment
Open pit mining is undertaken using a conventional truck-and-shovel fleet, using the equipment listed in Table 13-2.
13.9 Personnel
The LOM personal requirements for LOM mine operations including mine operation/maintenance and mine technical services is 1,270.
| | | | | | | | |
Date: February 2022 | | Page 13-4 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Table 13-1: LOM Production Plan Forecast
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Item | Unit | Total | 2022 | 2023 | 2024 | 2025 | 2026 | 2027 | 2028 | 2029 | 2030 | 2031 |
Material mined | M tonnes | 1,262 | 193 | 193 | 169 | 152 | 140 | 116 | 96 | 66 | 65 | 34 |
Ore processed | M tonnes | 362 | 37 | 34 | 37 | 39 | 38 | 36 | 37 | 35 | 37 | 33 |
Note: Numbers have been rounded; totals may not sum due to rounding.
Table 13-2: LOM Equipment List
| | | | | | | | |
Item/Purpose | Comment | Peak Number |
Bucyrus 495 | Rope shovel | 5 |
Komatsu PC8000 | Hydraulic shovel | 2 |
Komatsu PC5500 | Hydraulic shovel | 1 |
Komatsu WA1200 | Loader | 2 |
Komatsu 930 | Haul truck | 82 |
Cat777 | Haul truck | 4 |
Pit Viper 351 | Production drill | 4 |
Pit Viper 271 | Production drill | 5 |
Flexiroc D65 | Pre-split drill | 4 |
Komatsu D475 | Track dozer | 4 |
Cat D11 | Track dozer | 6 |
Komatsu WD900 | Wheel dozer | 7 |
Cat 24m | Grader | 7 |
| | | | | | | | |
Date: February 2022 | | Page 13-5 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
14.0 RECOVERY METHODS
14.1 Process Flow Sheet
14.1.1 Introduction
The Peñasquito Operations consist of a heap leach gold and silver recovery facility which is no longer in production since August 2020 and a sulfide plant that processes a maximum of 119,000 t/d of sulfide ore according to the 2021 throughout model.
The process plants were designed on a range of hardness, but as the mine has become deeper, the softer oxide ores are no longer the predominant feed material.
The oxide flowsheet is included as Figure 14-1. A schematic of the sulfide process flowsheet is included as Figure 14-2 for the lead–zinc portion of the flowsheet, and in Figure 14-3 for the precious metals plant portion of the flowsheet.
The oxide plant is no longer in production as of August 2020. The heap leach pad is being recirculated with water while closure plans are under development. The areas of the circuit above the purple dotted line are only recirculating water with no production. The area (refinery) below the purple line is being used to treat pyrite leach plant calcines.
14.2 Plant Design
14.2.1 Oxide Plant
As of August 2020, the oxide plant is no longer in production and is being recirculated with water. Closure plans are under development for the heap leach pad.
14.2.2 Sulfide Plant
ROM ore is delivered to the crusher dump pocket from the mine by 290 t rear-dump–haul trucks. The crushing circuit is designed to process 136,000 t/d of ROM ore to 80% passing 150 mm. The crushing facility consists of a gyratory crusher capable of supporting the 92% utilization on a 24-hour-per-day, 365-days-per-year basis of the processing plant. A near-pit sizing conveyor (NPSC) supports higher throughputs by facilitating waste removal.
Product from the gyratory crusher discharges into a 500 t surge pocket directly below the crusher. The crusher feeds, via an apron feeder, a coarse ore stockpile that has a 91,800 t live capacity. A total of 10 apron feeders arranged in two lines, of five feeders each, reclaim ore from the coarse ore stockpile. Nine feeders report the coarse ore to two semi-autogenous grinding (SAG) mills operating in closed circuit with pebble crushers and one high pressure grinding roller (HPGR) unit. Each SAG mill operates with two ball mills.
| | | | | | | | |
Date: February 2022 | | Page 14-1 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Figure 14-1: Simplified Oxide Flowsheet
Note: Figure prepared by Newmont, 2021.
| | | | | | | | |
Date: February 2022 | | Page 14-2 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Figure 14-2: Sulfide Process Flowsheet (base metals)
Note: Figure prepared by Newmont, 2020.
| | | | | | | | |
Date: February 2022 | | Page 14-3 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Figure 14-3: Sulfide Process Flowsheet (precious metals)
Note: Figure prepared by Newmont, 2020.
| | | | | | | | |
Date: February 2022 | | Page 14-4 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
The pebble crushing circuit includes three cone crushers working in parallel and one HPGR unit working in series with the cone crushers. An “augmented feed” secondary cone crusher is fed directly with coarse ore stockpile material by a single apron feeder and the product is dry screened. The oversize from the augmented feed crusher screen together with the oversize from the SAG trommel screens constitutes the feed to the pebble cone crushers. The pebble crusher product together with the fines produced by the augmented feed crusher screen are discharged to a bin that feeds the HPGR or, when necessary, feeds directly to the SAG mills.
Each grinding circuit reduces the crushed ore from a passing P80 of 159 mm size to a passing P80 of 125 µm. The SAG trommel screen undersize (minus 19 mm material) discharges to a common sump. Secondary grinding is performed in four ball mills, operating in closed circuit with cyclones. Ball mill discharge is combined with SAG mill trommel screen undersize and the combined slurry is pumped to the primary cyclone clusters. Cyclone underflow reports back to the ball mills. Cyclone overflow flows by gravity to the flotation area as final grinding product. The flotation area is comprised of carbon, lead and zinc flotation circuits.
The carbon pre-flotation circuit consists of two banks each with two cells of rougher in parallel. Carbon rougher concentrate proceeds to a single bank of three cleaner cells. The cleaner concentrate is treated in a single re-cleaner column, while the cleaner tails flow to a single bank of three cleaner-scavenger cells. Cleaner-scavenger concentrate returns to the cleaner circuit, while cleaner-scavenger tails are mixed with rougher tails which then become feed to the lead circuit. The recleaner column concentrate proceeds primarily to the tertiary precious metals recovery circuit, but can also be directed to final tails.
The lead rougher flotation consists of six rows of rougher flotation machines in parallel, each row consisting of five cells. Lead rougher concentrate is bypassed directly to the lead cleaner conditioning tank. Product at a passing P80 of 30 µm is cleaned in a three-stage cleaner circuit. Reagents are added into the rougher and cleaner circuits on as-required basis.
Tailings from the lead circuit flow by gravity to the zinc rougher conditioner tanks. One conditioner tank is installed for each bank of zinc rougher flotation cells. The conditioner tanks provide retention to facilitate activation of the sphalerite by copper sulfate addition. Collector is added to recover the zinc associated with activated sphalerite. Frother is added as required.
The slurry in the conditioners overflows to the zinc rougher flotation circuit, which consists of six banks of six tank-type, self-aerating, rougher flotation cells. Tailings from all rows of zinc rougher cells are combined in a tailings box and are pumped to the pyrite leach process (PLP) circuit. The rougher zinc concentrate is reground in vertical mills operating in closed circuit with cyclones. Product at a passing P80 of 30 µm is cleaned in a three-stage cleaner circuit. Reagents are added into the rougher and cleaner circuits on as-required basis.
Final lead and zinc concentrates are thickened, pressure filtered, and trucked to inland smelters or to ports for overseas shipment.
Table 17-1 lists the major equipment currently operating at the Peñasquito process plant.
| | | | | | | | |
Date: February 2022 | | Page 14-5 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Table 14-1: Process Equipment List, Sulfide Circuit
| | | | | | | | | | | |
Area | Equipment | Parameter | Value |
Crushing and grinding | Primary crusher | Type | FFE – gyratory crusher |
Size | 60” x 113” |
Conveyor belts | Width | 72” |
Coarse ore stockpile | Live Capacity | 91,800 t |
Total Live Capacity | 238,800 t |
Apron feeders | Quantity | 5 per line |
Dimensions | 48” x 17” |
Augmented crusher | Type | Cone crusher |
Model | Raptor XL 1100 |
Motor | 820 kW |
SAG mill | Quantity | 2 |
Type | FFE – SAG gearless |
Size | 11.6 m x 6.1 m |
Motor | 19,400 kW |
Ball mill | Quantity | 4 (2 lines) |
Type | FFE – Ball mill |
Size | 7.3 m x 11.3 m |
Motor | 6,000 kW synchronous |
Cyclones | Quantity | 24 (4 cyclobanks) |
Type | G-max 33 |
Pebble crusher | Quantity | 3 |
Type | Sandvik CH880 |
Motor | 600 kW |
HPGR | Quantity | 1 |
Type | Polycom 24/17” |
Motor | 5,000 kW |
Carbon pre-flotation circuit | Rougher flotation | Type | Outotec |
Quantity | 2 banks of 2 cells |
Volume | 630 m3 |
Cleaner flotation | Type | Outotec |
Quantity | 1 bank of 3 cells |
Volume | 300 m3 |
Scavenger flotation | Type | Outotec |
Quantity | 1 bank of 3 cells |
Volume | 300 m3 |
Re-cleaner flotation | Type | Outotec |
Quantity | 1 column cell |
Dimensions | 5.5 m diameter x 14 m |
Tertiary precious metals recovery circuit | Gravity concentrator | Type | Falcon ultrafine gravity concentrator |
Quantity | 32 |
Size | 1.5 m dia |
| | | | | | | | |
Date: February 2022 | | Page 14-6 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
| | | | | | | | | | | |
Area | Equipment | Parameter | Value |
Lead flotation circuit | Rougher flotation | Type | Wemco/Dorr Oliver |
Quantity | 30 (6 rows, 5 cells per row) |
Volume | 250 m3 |
1st cleaner | Quantity | 7 |
Volume | 42.5 m3 |
2nd cleaner | Quantity | 8 |
Volume | 2.5 m3 |
3rd cleaner | Quantity | 4 |
Volume | 2.5 m3 |
Zinc flotation circuit | Rougher flotation | Type | Wemco/Dorr Oliver |
Quantity | 36 (6 rows, 6 cells per row) |
Volume | 250 m3 |
1st cleaner | Quantity | 7 |
Volume | 42.5 m3 |
2nd cleaner | Quantity | 8 |
Volume | 8.5 m3 |
3rd cleaner | Quantity | 5 |
Volume | 8.5 m3 |
Vertical mill | Quantity | 2 |
Type | Metso – 485 kW |
Lead concentrate thickening | Thickener | Quantity | 2 |
Type | Outokumpu – high rate |
Size | 10 m (32.81 ft.) dia |
Storage tank | Quantity | 2 |
Size | 325 m3 |
Zinc concentrate thickening | Thickener | Quantity | 2 |
Type | Outokumpu – high rate |
Size | 14 m (45.93 ft.) dia |
Storage tank | Quantity | 2 |
Size | 325 m3 |
Lead concentrate filtering | Filters | Type | Pneumapress 14 plates |
Size | 2.8 m2 |
Quantity | 3 |
Zinc concentrate filtering | Filters | Type | Pneumapress 14 plates |
Size | 2.8 m2 |
Quantity | 3 |
Tailings classification | Cyclone towers | Quantity | 2 (north tower & south tower) |
Cyclone feed pumps | Type | 600 mm x 650 mm GIW |
Quantity | 3 per tower |
Cyclone cluster | Type | Gmax 20 |
Quantity | 15 cyclones per cluster |
Quantity | 2 clusters per tower |
| | | | | | | | |
Date: February 2022 | | Page 14-7 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
14.2.3 Pyrite Leach Process
The slurry in the conditioners overflow to the zinc rougher flotation circuit, which consists of six banks of six tank-type, self-aerating, rougher flotation cells. Tailings from all rows of zinc rougher cells are combined in a tailings box and are pumped to the pyrite circuit (PLP). The rougher zinc concentrate is reground in vertical mills operating in closed circuit with cyclones. Product at a passing P80 of 30 µm is cleaned in a three-stage cleaner circuit. Reagents are added into the rougher and cleaner circuits on as-required basis. Numerous variations in mineralogy, head grade (specifically % S in the feed stream) and metallurgical response will cause potential fluctuations in the rougher and cleaner concentrate grades and metal recovery. Similarly, the performance of the regrind mill circuits, agitated leach extraction, and counter-current decant (CCD) washing efficiency will also be affected. Therefore, equipment specification includes a percentage variation allowance in both the feed and throughput characteristics.
The PLP circuit treats the zinc rougher tailing from the concentrator for recovery of residual gold and silver. The process comprises pyrite rougher and cleaner flotation, pre-cleaner concentrate regrinding, pyrite thickening, and post-cleaner regrind, agitated tank leaching, counter-current decantation, Merrill-Crowe precipitation, precious metals refining and a cyanide detoxification circuit. The PLP circuit produces doré bars. The tailing streams report to the existing TSF.
The major equipment list for the PLP circuit is included in Table 14-2.
Table 14-2: Pyrite Leach Process Equipment List and Specifications
| | | | | | | | |
Area | Parameter | Value |
Rougher flotation | Residence time | 28 min |
Cell arrangement | 3 banks of 5 630 m3 tank cells |
Pre-cleaner regrind | Configuration | Vertical mill in open circuit |
Installed power | 3.5 MW |
Cleaner flotation | Residence time | 12.8 min |
Cell arrangement | Single bank of 3 cells |
High rate thickening | Diameter | 35 m |
Post-cleaner regrind | Mill type | ISAMILL |
Number of mills | 4 |
Pre-leach flotation | Residence time | 5 min |
Cell arrangement | Single bank of three 130 m3 cells |
Leach circuit | Residence time | 24 h |
Number of tanks | 1 pre-aeration/5 leaching |
Counter current decantation | Number of stages (thickeners) | 4 high rate |
Diameter | 30 m |
Cyanide detoxification | Residence time | 4 h |
Treatment method | Air/SO2 |
Number of tanks | 2 in series. |
Metal recovery (Merill-Crowe) | Design flow | 1,969 m3/h |
Clarification filters (horizontal pressure) | 5 operating/1 standby |
Precipitation filters (plate and frame) | 5 operating/1 standby |
| | | | | | | | |
Date: February 2022 | | Page 14-8 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
14.2.4 Tertiary Precious Metals Recovery Process
The tertiary precious metals recovery process has not been operated because, as of the Report date, the organic carbon grades had not been high enough to operate this circuit. It is expected that organic carbon grades will increase after mid-2022 and the circuit may become operational from that point onward.
The tertiary precious metals recovery circuit was installed to minimize precious metal lost with the carbon pre-flotation process carbon concentrate, and to indirectly recover precious metal value associated with the PLP pre-leach flotation concentrate, which will be directed to the carbon pre-treatment cleaner flotation cells. Without the tertiary precious metals recovery, the carbon concentrate and contained gold and silver values would be directed to tailings.
Final carbon concentrate from the carbon pre-treatment step would be directed to a gravity concentration circuit, consisting of 32 ultrafine gravity concentrators operating in parallel.
Feed from the carbon pre-flotation circuit would be pumped to a pressurized distributor that divides the dilute slurry into eight concentrator feed tanks. Each of the feed tanks would supply slurry to the four associated gravity concentrators. The concentrators would produce a precious metals concentrate that would be collected in a single pumpbox and pumped to both trains of the lead cleaner circuit. The concentrator tail would be collected in a launder and sent to final tailings by gravity. A sampler would be located on the tailing discharge for metallurgical accounting.
Ancillary services would include:
•Dedicated low pressure compressors to deliver plant air;
•Fresh water delivery system;
•Gland water delivery system;
•Process water for hose stations;
•Instrument dry air;
The underflow Falcon units are rated to handle 20 m3/hr of slurry. With 32 operable units the maximum design flow is 640 m3/hr. The unit capacities are based on volumetric loading, with recommended solids densities in the feed between 5–15%. Based on testwork carried out to date, pulp densities in the feed to the underflow Falcon are likely to be in the range of 5% and contained solids less than 30 t/hr.
Site and corporate staff continue to study the impact of organic carbon, the expected performance of the tertiary precious metals recovery process plant, and other options for handling high organic carbon mineralization.
14.3 Energy, Water, and Process Materials Requirements
14.3.1 Energy
Newmont currently uses power sourced from Saavi Energia (formerly Intergen) located in San Luis de la Paz, Guanajuato as its central power grid; however, the Peñasquito Operations are still using Mexican Electricity Federal Commission infrastructure to bring the electricity from
| | | | | | | | |
Date: February 2022 | | Page 14-9 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Guanajuato to Mazapil. The annual power consumption ranges from 165–175 MW per day. The processing plant accounts for around 85% of the total consumption.
14.3.2 Consumables
Reagents are typically trucked to site and stored onsite in quantities sufficient for mine usage, plus sufficient supply to cover potential interruptions in the delivery of the reagents. The major reagents include:
•Sulfide plant: collectors, depressants, frothers and activators;
•Precious metals plant: lime, flocculant and zinc.
Other consumables include grinding media, oxygen and air.
14.3.3 Water Supply
Water is sourced from several locations: the tailings storage facility (TSF), well fields, pit dewatering wells, and process operational recycle streams.
The operating philosophy is to maximize the amount of recycled water within the process plant, and a significant proportion of the total mine site water requirements is made up from recycled water. Fresh water is used only for reagent makeup and gland service water for the pumps.
14.4 Personnel
The process personnel required for the LOM plan total 754 including plant operations and maintenance.
| | | | | | | | |
Date: February 2022 | | Page 14-10 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
15.0 PROJECT INFRASTRUCTURE
15.1 Introduction
Site infrastructure comprises:
•Two open pits: Peñasco and Chile Colorado;
•Three waste rock facilities (with conveying and stacking system for the NPSC waste facility);
•One concentrator plant and associated conveying systems;
•One heap leach pad and Merrill Crowe plant;
•Camp/accommodation complex;
•Maintenance, administration and warehouse facilities;
•TSF;
•Medical clinic;
•Various ancillary buildings;
•Paved airstrip;
•Diversion channels;
•Pipelines and pumping systems for water and tailings;
•Access roads;
•Explosive storage facilities;
•High-voltage transmission line;
•Environmental monitoring facilities.
Figure 15-1 is an infrastructure layout plan for the Project.
15.2 Road and Logistics
Road access is outlined in Chapter 4.2. Within the Project area, access is by foot trails and tracks.
The Peñasquito mine has a 610 m long (2,000 ft) asphalt airstrip and associated terminal building.
| | | | | | | | |
Date: February 2022 | | Page 15-1 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Figure 15-1: Infrastructure Layout Plan
Note: Figure prepared by Newmont, 2020.
15.3 Stockpiles
Stockpile classification is based on material types that require different treatment at the mill, with three major stockpile types, organic carbon (<0.30% C), low lead (<0.20% Pb), and high lead (>0.20% Pb). The high-lead stockpile is subdivided into three types, based on gold content, which are designated low (<0.30 g/t Au), medium (>0.30–<0.49 g/t au), and high (>0.50 g/t Au).
In late 2019, ore control started working on an estimation of a stockpile block model. The model was built using dumping locations and grades. These data are cross-checked with the weekly stockpile topographic surface to obtain more accurate grades by area. The block model grades are used to estimate short-term plans and to optimize blending.
15.4 Waste Rock Storage Facilities
The approximate 900 Mt of waste rock remaining to be mined in the LOM plan will be stored in a series of five waste rock storage facilities (WRSFs). The remaining storage capacity in these facilities is about 1,140 Mt. All facilities are located with Newmont’s overall operating area. The development schedule for each facility is based on an optimization of the overall haulage profile, the requirements for waste material for tailing storage, and the incorporation of additional haulage trucks into the current mining fleet.
| | | | | | | | |
Date: February 2022 | | Page 15-2 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
The current WRSF strategy does not consider pit backfilling. All of the WRSFs are located well beyond the crest of the ultimate pit; however, further optimization of the LOM waste storage plan will continue to be examined by Newmont, in an effort to further reduce haulage profiles and resulting unit mining costs.
The WRSF designs were reviewed by Golder, a third-party consultant. Factors of safety range from 1.2 to 1.3.
15.5 Tailings Storage Facilities
15.5.1 Tailings Storage
Four perimeter containment structures, the north, south, east, and west dams, provide containment of the tailings at the existing storage facility. The north, west, and south dams were constructed using centerline methods. The eastern dam is a geomembraned and bituminous geomembraned-lined water-retaining dam constructed of rockfill using a downstream raise configuration. The internal water reclaim pond is maintained against this structure. Key elements of the TSF include:
•Whole tailings classification, transport and distribution systems (including pipelines and north and south cyclone stations);
•Whole tailings dams (basin area);
•Seepage collection system, including tanks, pumps, and pipelines;
•Water reclaim system, including pumps, tanks, and pipelines (reclaim pond).
The TSF is currently constructed to an ultimate dam crest elevation of 1,867.2 masl; however, future plans for the TSF include its raising to 1,912.7 masl. The maximum storage allowed under the current tailings dam construction plan at elevation 1907.7 masl is 383 Mt, consisting of 356 Mt of stored tailings and 27 Mt of hydraulic sand construction.
Construction of an additional buttress commenced in 2017 with an approximate width of 80 m at the base. The buttress uses mine waste and continues to be developed as a stability measure.
15.5.2 Tailings Reclaim Pond
The water reclaim from the TSF originates from four sources: precipitation falling within the TSF footprint and contributing area; reclaim water from the tailing depositional process; seepage water that is returned to the TSF; and freshwater pumped from groundwater sources into the water reclaim pond.
15.5.3 External Ponds
Four ponds are sited to the east of the TSF, and are referred to as the external ponds. The ponds are designed to reduce the solids content of the reclaim water, as well as provide water storage to accommodate fluctuations in plant operations, fresh water supplies, precipitation, evaporation, and other variables that feed into the site-wide water balance.
15.6 Water Management
| | | | | | | | |
Date: February 2022 | | Page 15-3 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
15.6.1 Water Sources
The mine is located in Mazapil valley, which forms part of the Cedros administrative aquifer. Hydrologically, this aquifer is part of the Nazas Aguanaval sub-basin, which forms part of the Laguna de Mayrán y Viesca Regional Basin. Because there are no surface water resources, the water supply for the Peñasquito Operations is obtained from groundwater in the Cedros basin, from an area known as the Torres and Vergel well field.
The mine has received permits to pump up to 35.247 Mm³ of this water per year via eight water rights titles over the Torres and Vergel water well field and Northern Well field (NWF). The Torres and Vergel well field (16 wells) is being pumped at an average daily rate of approximately 31,000 m³ per day. The NWF well field extracts approximately 30,000 m³ per day (14 wells).
As much water as practicable is recycled.
Newmont continues to monitor the local aquifers to ensure they remain sustainable. A network of monitoring wells was established to monitor water levels and water quality.
15.6.2 Dewatering Activities
Dewatering wells from the open pit area are currently sufficient being pumped at an average rate of 27,500 m³/d. This rate as well as currently budgeted replacement wells is sufficient for LOM dewatering. Water is used by the mine and plant, as required.
15.6.3 Water Balance
A probabilistic water balance model was developed for the entire mine site including the plant, heap leach facilities, diversion channels, tailings facility, other users of water, and the water supply system. The software used for this water balance is the industry standard GoldSim modeling package. This model is tracked and updated on a monthly basis. Modelling allows Newmont to define initial and operating conditions within the Peñasquito mine system and simulate the projected performance of the mine water system over a given time period.
The mine is operated as a zero-discharge system. Peñasquito does not discharge process water to surface waters, and there are no direct discharges to surface waters.
15.6.4 Waste Water
All wastewater from the mine offices, camp and cafeteria is treated in a wastewater treatment plant prior to discharge to the environment.
All storm water is diverted from the main infrastructure facilities through use of diversion channels.
15.7 Camps and Accommodation
On-site accommodation comprises a 3,421-bed camp with full dining, laundry and recreational facilities.
| | | | | | | | |
Date: February 2022 | | Page 15-4 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
15.8 Power and Electrical
Power is currently supplied from the 182 MW power purchase agreement with Saavi Energia, delivered to the mine by the Mexican Federal Electricity Commission (Comisión Federal de Electricidad or CFE). CFE also continues to provide backup power supply for both planned and unplanned shutdowns from the Saavi Energia power plant.
| | | | | | | | |
Date: February 2022 | | Page 15-5 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
16.0 MARKET STUDIES AND CONTRACTS
16.1 Market Studies
Bullion from the Peñasquito Operations is sold on the spot market, by corporate in-house marketing experts. The terms in these contracts are in line with industry standard terms and are consistent with doré sold from other operations. The doré is not subject to product specification requirements.
Newmont has established contracts and buyers for its lead and zinc concentrate, and has a corporate internal marketing group that monitors markets for its concentrate. Together with public documents and analyst forecasts, these data support that there is a reasonable basis to assume that for the LOM plan, that the lead and zinc concentrate will be saleable at the assumed commodity pricing.
The lead concentrate produced at Peñasquito is marketed as a high gold and high silver, lead concentrate. Smelters operating their own precious metal refineries (with a strong ability to recover gold) at their lead smelting operations are best prepared to contract for Peñasquito lead concentrates. The zinc concentrate produced at Peñasquito is marketed as a high gold and high silver, zinc concentrate. Smelters with the ability to recover gold and silver from their zinc processes are best prepared to contract for Peñasquito zinc concentrates. Long-term contracts have been negotiated with smelters in Korea, Spain, Antwerp, Canada, Mexico and Japan for a large portion of the mine production of concentrates. The remaining production is tendered on the spot market. The pricing of the concentrate is driven by London Metal Exchange (LME) lead and zinc pricing, London Bullion Market Association (LBMA) gold and silver pricing, and annual processing benchmark terms negotiated by major industry players and published by third-party data providers.
There are no agency relationships relevant to the marketing strategies used.
16.2 Forward Sales Agreements
As of December 31, 2021, Newmont had not entered into forward sales agreements for the base metals volumes in relation to Peñasquito concentrate sales
16.3 Commodity Price Forecasts
Newmont uses a combination of historical and current contract pricing, contract negotiations, knowledge of its key markets from a long operations production record, short-term versus long-term price forecasts prepared by Newmont’s corporate internal marketing group, public documents, and analyst forecasts when considering long-term commodity price forecasts.
Higher metal prices are used for the mineral resource estimates to ensure the mineral reserves are a sub-set of, and not constrained by, the mineral resources, in accordance with industry-accepted practice.
| | | | | | | | |
Date: February 2022 | | Page 16-1 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
The long-term commodity price and exchange rate forecasts are:
Mineral reserves:
•Gold: $1,200/oz;
•Silver: $20/oz;
•Lead: $0.90/lb;
•Zinc: $1.15/lb;
•Mexican peso to US$: 19.5.
Mineral resources:
•Gold: $1,400/oz;
•Silver: $23/oz;
•Lead: $1.10/lb;
•Zinc: $1,40/lb;
•Mexican peso to US$: 19.5.
16.4 Contracts
Newmont has contracts in place for the majority of the lead and zinc concentrate. The terms contained within the concentrate sales contracts are typical and consistent with standard industry practice for lead and zinc concentrates with high gold and silver contents.
The contracts include industry benchmark terms for metal payables, treatment charges and refining charges for concentrates produced. Depending on the specific contract, the terms for the sale of the lead and zinc concentrates are either referenced to benchmark-based treatment and refining charges, or negotiated fixed terms.
Treatment charges assumed for estimation of mineral reserves are based forecasts published by third party data providers such as Wood Mackenzie or the CRU Group. The formula used for mineral reserves is sensitive to the underlying metal prices (gold, silver, lead, zinc) and is consistent with long-term expectations for lead and zinc treatment and gold and silver refining charges in lead concentrates.
Newmont’s bullion is sold on the spot market, by in house marketing experts. The terms in these contracts are in line with industry standard terms and are consistent with doré sold from other operations.
The largest in-place contracts other than for product sales cover items such as bulk commodities, operational and technical services, mining and process equipment, and administrative support services. Contracts are negotiated and renewed as needed. Contract terms are typical of similar contracts in Mexico that Newmont is familiar with.
| | | | | | | | |
Date: February 2022 | | Page 16-2 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
17.0 ENVIRONMENTAL STUDIES, PERMITTING, AND SOCIAL OR COMMUNITY IMPACT
17.1 Baseline and Supporting Studies
The key baseline studies completed over the Project area in support of the original environmental assessment and later Project expansion included:
•Hydrogeology and groundwater quality;
•Aquifer assessments;
•Surface water quality and sediment;
•Metals toxicity and acid mine drainage studies;
•Air and climate;
•Noise and vibration;
•Vegetation;
•Wildlife;
•Conservation area management plan;
•Biomass and carbon fixation studies;
•Land use and resources;
•Socio-economics.
17.2 Environmental Considerations/Monitoring Programs
Environmental monitoring is ongoing at the Project and will continue over the life of the operations. Key monitoring areas include air, water, noise, wildlife, forest resources and waste management.
Characterization studies of waste rock, pit walls, and tailings materials were undertaken to determine the acid rock drainage (ARD) and metal leaching (ML) potential. Peñasco and Chile Colorado waste rock was found to have low potential for acidic drainage from the oxidized waste rock lithologies. However, there was potential for waste rock with sulfides to oxidize to produce acidity; however, this could be controlled by adequate neutralization in these materials to overcome acidic drainage. Potentially acid-forming waste (PAG) materials and rock types that have ML potential are currently stored in the waste rock facilities and encapsulated with non-reactive rock. The tailings materials have somewhat higher potential to produce ARD and ML (selenium being the only metal potentially outside Mexican standards). Control of ARD and ML from tailings materials will be achieved through reclamation of the current TSF after its closure in 2027, concurrent with ongoing mining activities, and reclamation of the final TSF immediately after mine closure.
| | | | | | | | |
Date: February 2022 | | Page 17-1 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
17.3 Closure and Reclamation Considerations
A closure and reclamation plan was prepared for the mine site. The cost for this plan was calculated based on the standard reclamation cost estimator (SRCE) model which is based on the Nevada State regulations. The closure cost spending schedule was updated for the current mine life, and reflects anticipated expenditures prior to closure, during decommissioning and during the post-closure monitoring and maintenance period. Site closure costs are funded by allocating a percentage of sales revenue to closure activities.
The closure and reclamation plan also incorporates international best practices, including the World Bank Environment, Health and Safety Guidelines Mining and Milling - Open Pit, the Draft International Finance Corporation (IFC) Environmental, Health and Safety Guidelines – Mining, and the International Cyanide Management Code For the Manufacture, Transport, and Use of Cyanide in the Production of Gold.
Mexican legislation does not require the posting of reclamation or performance bonds.
Current 2021 asset retirement obligation (ARO) closure costs are estimated at approximately US$0.5 B for rehabilitation activities associated with existing disturbance.
The closure costs used in the economic analysis total US$0.8 B.
A comprehensive study is ongoing to potentially resettle the communities in close proximity to the mine - any such decision will require approval from the Newmont’s senior management, and will have impacts on future closure cost estimates.
17.4 Permitting
All major permits and approvals are in place to support operations. Where permits have specific terms, renewal applications are made of the relevant regulatory authority as required, prior to the end of the permit term.
Newmont monitors the regulatory regime in place at each of its operations and ensures that all permits are updated in line with any regulatory changes.
17.5 Social Considerations, Plans, Negotiations and Agreements
Public consultation and community assistance and development programs are ongoing.
Newmont, Ejido Cedros and Ejido Mazapil have established trust funds for locally-managed infrastructure, education and health projects. Newmont provides annual funding for these trusts. The communities around the Peñasquito mine also benefit from a number of programs and services provided, or supported, by the mine. In addition, the Peñasquito mine operates a forestry nursery that produces 3.5 million trees annually. These trees are used for reforestation around the mine and within the local communities.
| | | | | | | | |
Date: February 2022 | | Page 17-2 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
17.6 Qualified Person’s Opinion on Adequacy of Current Plans to Address Issues
Based on the information provided to the QP by Newmont (see Chapter 25), there are no material issues known to the QP. The Peñasquito Operations are mature mining operations and currently has the social license to operate within its local communities.
| | | | | | | | |
Date: February 2022 | | Page 17-3 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
18.0 CAPITAL AND OPERATING COSTS
18.1 Introduction
Capital and operating cost estimates are at a minimum at a pre-feasibility level of confidence, having an accuracy level of ±25% and a contingency range not exceeding 15%.
18.2 Capital Cost Estimates
Capital costs are based on recent prices or operating data. Capital costs include funding for infrastructure, pit dewatering, development drilling, and permitting as well as miscellaneous expenditures required to maintain production. Mobile equipment re-build/replacement schedules and fixed asset replacement and refurbishment schedules are included. Sustaining capital costs reflect current price trends.
The overall capital cost estimate for the LOM is US$1.1 B, as summarized in Table 18-1.
18.3 Operating Cost Estimates
Operating costs are based on actual costs seen during operations and are projected through the LOM plan. Historical costs are used as the basis for operating cost forecasts for supplies and services unless there are new contract terms for these items. Labor and energy costs are based on budgeted rates applied to headcounts and energy consumption estimates.
Operating costs for the LOM are estimated at US$7.4 B, as summarized in Table 1-14. The estimated LOM mining cost is US$2.03/t. Base processing costs are estimated at US$10.25/t. In addition, G&A costs are estimated at US$3.40/t.
Table 18-1: Capital Cost Estimate
| | | | | | | | |
Area | Unit | Value |
Mining | US$ B | 0.3 |
Process | US$ B | 0.5 |
Site G&A | US$ B | 0.4 |
Total | US$ b | 1.1 |
Note: Numbers have been rounded; totals may not sum due to rounding.
Table 18-2: Operating Cost Estimate
| | | | | | | | |
Area | Unit | Value |
Mining | US$ B | 2.5 |
Process | US$ B | 3.7 |
G&A | US$ B | 1.2 |
Total | US$ B | 7.4 |
Note: Numbers have been rounded; totals may not sum due to rounding.
| | | | | | | | |
Date: February 2022 | | Page 18-1 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
19.0 ECONOMIC ANALYSIS
19.1 Methodology Used
The financial model that supports the mineral reserve declaration is a standalone model that calculates annual cash flows based on scheduled ore production, assumed processing recoveries, metal sale prices and MXN$/US$ exchange rate, projected operating and capital costs and estimated taxes.
The financial analysis is based on an after-tax discount rate of 8%. All costs and prices are in unescalated “real” dollars. The currency used to document the cash flow is US$.
All costs are based on the 2022 budget. Revenue is calculated from the recoverable metals and long-term metal price and exchange rate forecasts.
19.2 Financial Model Parameters
The economic analysis is based on the metallurgical recovery predictions in Chapter 10.4, the mineral reserve estimates in Chapter 13, the mine plan discussed in Chapter 14, the commodity price forecasts in Chapter 16, closure cost estimates in Chapter 17.4, and the capital and operating costs outlined in Chapter 18. Royalties were summarized in Chapter 3.9.
The Peñasquito Operations are subject to a federal tax of 30%, and mining tax of 7.5%.
The economic analysis is reported on a 100% project ownership basis. The economic analysis assumes constant prices with no inflationary adjustments.
The NPV8% is US$1.7 B. As the cashflows are based on existing operations where all costs are considered sunk to 1 January 2022, considerations of payback and internal rate of return are not relevant.
A summary of the financial results is provided in Table 19-1. An annualized cashflow statement is provided in Table 19-2. In these tables, EBITDA = earnings before interest, taxes, depreciation and amortization. The active mining operation ceases in 2031; however, closure costs are estimated to 2071. The closure costs, from 2032–2071 total US$0.6 B.
19.3 Sensitivity Analysis
The sensitivity of the Project to changes in metal prices, exchange rate, sustaining capital costs and operating cost assumptions was tested using a range of 25% above and below the base case values (Figure 19-1).
The Project is most sensitive to metal price changes, less sensitive to changes in operating costs, and least sensitive to changes in capital costs.
The sensitivity to grade mirrors the sensitivity performed for the commodity prices and is not shown.
| | | | | | | | |
Date: February 2022 | | Page 19-1 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Table 19-1: Cashflow Summary Table
| | | | | | | | |
Item | Unit | Value |
Metal Prices |
Gold | US$/oz | 1,200 |
Silver | US$/oz | 20 |
Lead | US$/lb | 0.90 |
Zinc | US$/lb | 1.15 |
Mined Ore |
Tonnage | Mtonnes | 362 |
Gold grade | g/t | 0.54 |
Silver grade | g/t | 33.84 |
Lead grade | % | 0.32 |
Zinc grade | % | 0.78 |
Gold ounces | Moz | 6.3 |
Silver ounces | Moz | 394 |
Lead pounds | Blb | 2.6 |
Zinc pounds | Blb | 6.2 |
Capital costs | US$B | 1.1 |
Costs applicable to sales | US$B | 8.8 |
Discount rate | % | 8 |
Exchange rate | United States dollar:Mexican peso (USD:MXN) | 19.5 |
Free cash flow | US$B | 2.3 |
Net present value | US$B | 1.7 |
Note: Numbers have been rounded; totals may not sum due to rounding. Table 19-1 contains “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, which are intended to be covered by the safe harbor created by such sections and other applicable laws. Please refer to the note regarding forward-looking information at the front of the Report. The cash flow is only intended to demonstrate the financial viability of the Project. Investors are cautioned that the above is based upon certain assumptions which may differ from Newmont’s long-term outlook or actual financial results, including, but not limited to commodity prices, escalation assumptions and other technical inputs. For example, Table 19-1 uses the price assumptions stated in the table, including a gold commodity price assumption of US$1,200/oz, which varies significantly from current gold prices and the assumptions that Newmont uses for its long-term guidance. Please be reminded that significant variation of metal prices, costs and other key assumptions may require modifications to mine plans, models, and prospects.
| | | | | | | | |
Date: February 2022 | | Page 19-2 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Table 19-2: Annualized Cashflow (2022–2032)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Item | Units | Total | 2022 | 2023 | 2024 | 2025 | 2026 | 2027 | 2028 | 2029 | 2030 | 2031 | 2032 |
Material mined | M tonnes | 1,262 | 193 | 193 | 169 | 152 | 140 | 116 | 96 | 66 | 65 | 34 | — |
Ore processed | M tonnes | 362 | 37 | 34 | 37 | 39 | 38 | 36 | 37 | 35 | 37 | 33 | — |
Contained gold, processed | Moz | 6.3 | 0.8 | 0.7 | 0.9 | 0.5 | 0.6 | 0.7 | 0.5 | 0.4 | 0.8 | 0.3 | 0.0 |
Contained silver, processed | Moz | 394 | 40 | 43 | 47 | 52 | 35 | 37 | 36 | 28 | 42 | 33 | — |
Contained lead, processed | Mlbs | 2,576 | 231 | 269 | 338 | 307 | 207 | 321 | 250 | 239 | 264 | 151 | — |
Contained zinc, processed | Mlbs | 6,249 | 567 | 655 | 822 | 851 | 665 | 630 | 524 | 409 | 742 | 384 | — |
Processed ore gold grade | g/t | 0.54 | 0.63 | 0.64 | 0.79 | 0.41 | 0.51 | 0.61 | 0.44 | 0.37 | 0.70 | 0.33 | — |
Processed ore silver grade | g/t | 33.84 | 33.48 | 39.84 | 38.89 | 42.03 | 29.07 | 32.51 | 30.36 | 24.38 | 35.51 | 31.81 | — |
Processed ore lead grade | % | 0.32 | 0.28 | 0.36 | 0.41 | 0.36 | 0.25 | 0.41 | 0.31 | 0.31 | 0.33 | 0.21 | 0.00 |
Processed ore zinc grade | % | 0.78 | 0.69 | 0.88 | 1.00 | 1.00 | 0.80 | 0.80 | 0.64 | 0.53 | 0.92 | 0.53 | 0.00 |
Recovered gold | Moz | 4.3 | 0.5 | 0.5 | 0.7 | 0.3 | 0.4 | 0.5 | 0.3 | 0.2 | 0.6 | 0.2 | 0.0 |
Recovered silver | Moz | 340 | 35 | 37 | 41 | 45 | 31 | 33 | 31 | 23 | 37 | 28 | — |
Recovered lead | Mlbs | 1,873 | 163 | 189 | 256 | 235 | 146 | 247 | 175 | 157 | 199 | 106 | — |
Recovered zinc | Mlbs | 5,043 | 452 | 524 | 676 | 703 | 538 | 513 | 415 | 311 | 611 | 301 | — |
Recovery, gold | % | 68 | 70 | 65 | 71 | 66 | 66 | 69 | 65 | 59 | 71 | 64 | 0 |
Recovery, silver | % | 86 | 87 | 86 | 88 | 86 | 86 | 88 | 85 | 82 | 89 | 85 | 0 |
Recovery, lead | % | 73 | 71 | 70 | 76 | 77 | 71 | 77 | 70 | 66 | 76 | 70 | 0 |
Recovery, zinc | % | 81 | 80 | 80 | 82 | 83 | 81 | 81 | 79 | 76 | 82 | 78 | 0 |
Net revenue | US$ B | 14.8 | 1.6 | 1.6 | 2.0 | 1.7 | 1.4 | 1.6 | 1.3 | 0.9 | 1.8 | 1.0 | 0.0 |
Costs applicable to sales | US$ B | -8.8 | -1.0 | -1.0 | -1.0 | -1.0 | -0.9 | -0.9 | -0.9 | -0.8 | -0.8 | -0.6 | 0.0 |
Other expenses | US$ B | -0.5 | -0.1 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
EBITDA | US$ B | 5.5 | 0.5 | 0.6 | 1.0 | 0.7 | 0.4 | 0.6 | 0.3 | 0.1 | 1.0 | 0.4 | 0.0 |
Operating cash flow (after estimated taxes and other adjustments) | US$ B | 3.5 | 0.3 | 0.3 | 0.6 | 0.5 | 0.3 | 0.4 | 0.3 | 0.2 | 0.6 | 0.4 | 0.0 |
Total capital | US$ B | -1.1 | -0.1 | -0.2 | -0.2 | -0.1 | -0.1 | -0.1 | -0.1 | -0.1 | -0.1 | -0.1 | 0.0 |
Free cash flow | US$ B | 2.3 | 0.1 | 0.2 | 0.4 | 0.4 | 0.2 | 0.3 | 0.2 | 0.1 | 0.5 | 0.3 | 0.0 |
Note: Numbers have been rounded; totals may not sum due to rounding. EBITDA = earnings before interest, taxes, depreciation and amortization. Table 19-2 contains “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, which are intended to be covered by the safe harbor created by such sections and other applicable laws. Please refer to the note regarding forward-looking information at the front of the Report. The cash flow is only intended to demonstrate the financial viability of the Project. Investors are cautioned that the above is based upon certain assumptions which may differ from Newmont’s long-term outlook or actual financial results, including, but not limited to commodity prices, escalation assumptions and other technical inputs. For example, Table 19-2 uses the price assumptions stated in the table, including a gold commodity price assumption of US$1,200/oz, which varies significantly from current gold prices and the assumptions that Newmont uses for its long-term guidance. Please be reminded that significant variation of metal prices, costs and other key assumptions may require modifications to mine plans, models, and prospects.
| | | | | | | | |
Date: February 2022 | | Page 19-3 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Figure 19-1: NPV Sensitivity
Note: Figure prepared by Newmont, 2021. FCF = free cashflow; op cost = operating cost; cap cost = capital cost; NPV = net present value.
| | | | | | | | |
Date: February 2022 | | Page 19-4 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
20.0 ADJACENT PROPERTIES
This Chapter is not relevant to this Report.
| | | | | | | | |
Date: February 2022 | | Page 20-1 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
21.0 OTHER RELEVANT DATA AND INFORMATION
This Chapter is not relevant to this Report.
| | | | | | | | |
Date: February 2022 | | Page 21-1 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
22.0 INTERPRETATION AND CONCLUSIONS
22.1 Introduction
The QP notes the following interpretations and conclusions, based on the review of data available for this Report.
22.2 Property Setting
The Peñasquito Operations are situated in an area that has had modern mining activities underway for about 14 years. As a result, local and regional infrastructure and the supply of goods available to support mining operations is well-established. Personnel with experience in mining-related activities are available in the district. Transportation routes access the Peñasquito Operations area.
There are no significant topographic or physiographic issues that would affect the Peñasquito Operations. The dominant vegetation types are cactus and coarse grasses.
Mining operations are conducted year-round.
22.3 Ownership
Newmont uses an indirectly 100% owned subsidiary, Minera Peñasquito SA de C.V. (Minera Peñasquito), as the operating entity for the mining operations.
22.4 Mineral Tenure, Surface Rights, Water Rights, Royalties and Agreements
Newmont currently holds 77 mining concessions (approximately 82,632 ha).
Surface rights in the vicinity of the Chile Colorado and Peñasco open pits are held by four ejidos. Newmont has entered into agreements with a number of ejidos in relation to surface rights, either for mining or exploration activities.
Newmont has active water extraction permits.
Wheaton pays Newmont a per-ounce cash payment of the lesser of US$3.90 and the prevailing market price (subject to an inflationary adjustment that commenced in 2011), for silver delivered under a streaming contract.
A 2% net smelter return (NSR) royalty is payable to Royal Gold on production from the Chile Colorado and Peñasco deposits. The Mexican Government levies a 7.5% mining royalty that is imposed on earnings before interest, taxes, depreciation, and amortization. There is also a 0.5% environmental erosion fee payable on precious based on gross revenues.
| | | | | | | | |
Date: February 2022 | | Page 22-1 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
22.5 Geology and Mineralization
The deposits within the Peñasquito Operations are considered to be examples of breccia pipe deposits developed as a result of intrusion-related hydrothermal activity.
The geological understanding of the settings, lithologies, and structural and alteration controls on mineralization in the different zones is sufficient to support estimation of mineral resources and mineral reserves. The geological knowledge of the area is also considered sufficiently acceptable to reliably inform mine planning.
The mineralization style and setting are well understood and can support declaration of mineral resources and mineral reserves.
Significant potential exists at depth below the current operating pits within the current diatreme bodies as well as skarn and mantos mineralization within the surrounding limestone units. Additionally, the surrounding district has relatively little exploration work completed.
22.6 History
The Peñasquito Operations have over 14 years of active mining history, and exploration activities date back to 1994 when the diatremes were first discovered.
22.7 Exploration, Drilling, and Sampling
The exploration programs completed to date are appropriate for the style of the mineralization within the Peñasquito Operations area.
Drilling is normally perpendicular to the strike of the mineralization. Depending on the dip of the drill hole, and the dip of the mineralization, drill intercept widths are typically greater than true widths.
Sampling methods, sample preparation, analysis and security conducted prior to Newmont’s interest in the operations were in accordance with exploration practices and industry standards at the time the information was collected. Current Newmont sampling methods are acceptable for mineral resource and mineral reserve estimation. Sample preparation, analysis and security for the Newmont programs are currently performed in accordance with exploration best practices and industry standards.
The quantity and quality of the lithological, geotechnical, collar and down-hole survey data collected during the exploration and delineation drilling programs are sufficient to support mineral resource and mineral reserve estimation. The collected sample data adequately reflect deposit dimensions, true widths of mineralization, and the style of the deposits. Sampling is representative of the gold and copper grades in the deposit, reflecting areas of higher and lower grades.
Density measurements are considered to provide acceptable density values for use in mineral resource and mineral reserve estimation.
| | | | | | | | |
Date: February 2022 | | Page 22-2 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
The sample preparation, analysis, quality control, and security procedures used by the Peñasquito Operations have changed over time to meet evolving industry practices. Practices at the time the information was collected were industry-standard, and frequently were industry-leading practices. The sample preparation, analysis, quality control, and security procedures are sufficient to provide reliable data to support estimation of mineral resources and mineral reserves.
The QA/QC programs adequately address issues of precision, accuracy and contamination. Modern drilling programs typically included blanks, duplicates and standard samples. QA/QC submission rates meet industry-accepted standards.
22.8 Data Verification
Newmont has data collection procedures in place that include several verification steps designed to ensure database integrity. Newmont staff also conducted regular logging, sampling, laboratory and database reviews. In addition to these internal checks, Newmont contracted independent consultants to perform laboratory, database and mine study reviews. The process of active database quality control and internal and external audits generally resulted in quality data.
The data verification programs concluded that the data collected from the Peñasquito Operations area adequately support the geological interpretations and constitute a database of sufficient quality to support the use of the data in mineral resource and mineral reserve estimation.
Data that were verified on upload to the database are acceptable for use in mineral resource and mineral reserve estimation.
The QP receives and reviews monthly reconciliation reports from the mine site. Through the review of these reconciliation factors the QP is able to ascertain the quality and accuracy of the data and its suitability for use in the assumptions underlying the mineral resource and mineral reserve estimates.
22.9 Metallurgical Testwork
Industry-standard studies were performed as part of process development and initial mill design. Subsequent production experience and focused investigations guided mill alterations and process changes. Testwork programs, both internal and external, continue to be performed to support current operations and potential improvements. From time to time, this may lead to requirements to adjust cut-off grades, modify the process flowsheet, or change reagent additions and plant parameters to meet concentrate quality, production, and economic targets.
Samples selected for testing were representative of the various types and styles of mineralization. Samples were selected from a range of depths within the deposit. Sufficient samples were taken so that tests were performed on sufficient sample mass.
Recovery factors estimated are based on appropriate metallurgical testwork, and are appropriate to the mineralization types and the selected process routes. However, the mineralogical complexity of the Peñasquito ores makes the development of recovery models difficult as eight elements (gold, silver, lead, zinc, copper, iron, arsenic, and antimony) are
| | | | | | | | |
Date: February 2022 | | Page 22-3 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
tracked through the process. Recovery models need to be sufficiently robust to allow for changes in mineralogy and plant operations, while providing reasonable predictions of concentrate quality and tonnage. LOM recovery forecasts the sulfide plant are 69% for gold, 87% for silver, 73% for lead, and 81% for zinc.
The mill throughput and associated recovery factors are considered appropriate to support mineral resource and mineral reserve estimation, and mine planning.
Sulfosalts can carry varying amounts of deleterious elements such as arsenic, antimony, copper and mercury. At the date of this Report, the processing plant, in particular the flotation portion of the circuit, does not separate the copper-bearing minerals from the lead minerals, so when present the sulfosalts report (primarily) to the lead concentrate. The future impact of the deleterious elements is thus highly dependent on the lead–copper ratio in ores. There is no direct effect of deleterious elements on the recovery of precious and base metals. The marketing contracts are structured to allow for small percentages of these deleterious elements to be incorporated into the final product, with any exceedances then incurring nominal penalties.
One small area of the mine was defined as containing above-average mercury grades. Due to its limited size, blending should be sufficient to minimize the impact of mercury from this area on concentrate quality.
Organic carbon has also been recognized as a deleterious element affecting the recovery of gold and the operational cost in the process plant. The carbon pre-flotation process was built to allow for removal of liberated organic carbon ahead of lead and zinc flotation and the pyrite leach plant, so that those process steps could operate in a similar fashion to operation with low-carbon ores.
22.10 Mineral Resource Estimates
Newmont has a set of protocols, internal controls, and guidelines in place to support the mineral resource estimation process, which the estimators must follow.
Estimation was performed by Newmont personnel. All mineralogical information, exploration boreholes and background information were provided to the estimators by the geological staff at the mines or by exploration staff. Modelling was performed in Leapfrog and MineSight software.
Mineral resources are reported using the mineral resource definitions set out in SK1300, and are reported exclusive of those mineral resources converted to mineral reserves. The reference point for the estimate is in situ.
Areas of uncertainty that may materially impact the mineral resource estimates include: changes to long-term commodity price assumptions; changes in local interpretations of mineralization geometry and continuity of mineralized zones; changes to geological shape and continuity assumptions; changes to metallurgical recovery assumptions; changes to the operating cut-off assumptions for mill feed or stockpile feed; changes to the input assumptions used to derive the conceptual open pit outlines used to constrain the estimate; changes to the cut-off grades used to constrain the estimates; variations in geotechnical, hydrogeological and mining assumptions; changes to governmental regulations, changes to environmental assessments, and changes to environmental, permitting and social license assumptions.
| | | | | | | | |
Date: February 2022 | | Page 22-4 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
22.11 Mineral Reserve Estimates
Mineral reserves were converted from measured and indicated mineral resources. Inferred mineral resources were set to waste. Estimation was performed by Newmont personnel.
The mine plan is based on a 36 Mt/a mill throughput. The schedule was developed at an NSR cut-off of US$14.61/t, incorporating the processing cost, metallurgical recovery, incremental ore mining costs, process sustaining capital and tailings dam related rehabilitation costs. The net revenue calculation assumes a gold price of US$1,200/oz, silver price of US$20/oz, lead price of US$0.90/lb and a zinc price of US$1.15/lb. The assumed exchange rate for mineral reserves was 19.5 Mexican pesos per US$. Mineral reserves are reported above an NSR cut-off of US$14.61/t.
The block models were constructed to include the expected dilution based on mining methods, bench height and other factors. The current mine and process reconciliation appears to support this assumption.
Stockpile estimates were based on mine dispatch data; the grade comes from closely-spaced blasthole sampling and tonnages were sourced from truck factors.
Mineral reserves are reported using the mineral reserve definitions set out in SK1300 The reference point for the point of delivery to the process plant.
Areas of uncertainty that may materially impact the mineral reserve estimates include: changes to long-term metal price and exchange rate assumptions; changes to metallurgical recovery assumptions; changes to the input assumptions used to derive the pit designs applicable to the open pit mining methods used to constrain the estimates; changes to the forecast dilution and mining recovery assumptions; changes to the cut-off values applied to the estimates; variations in geotechnical (including seismicity), hydrogeological and mining method assumptions; and changes to environmental, permitting and social license assumptions.
22.12 Mining Methods
Open pit mining is conducted using conventional techniques and an Owner-operated conventional truck and shovel fleet.
Open pit designs were assessed and reviewed prior to pit excavation to ensure adequacy and integrity of design geometry with consideration to ground conditions. As mining operations progress in the pit, additional geotechnical drilling and stability analysis will continue to be conducted to support optimization of the geotechnical parameters in the LOM designs.
A combination of Newmont staff and external consultants have developed the pit water management program, completed surface water studies, and estimated the life- of-mine site water balance. Management of water inflows to date have been appropriate, and no hydrological issues that could impact mining operations have been encountered.
The Peñasquito pit has four remaining stages (Phases 6 to 9), and will be excavated to a total depth of 780 m. The Chile Colorado pit has one remaining stage (Phase 2), and will reach 461 m ultimate depth. An ore stockpiling strategy is practiced.
The remaining mine life is 10 years, with the last year, 2031, being a partial year.
| | | | | | | | |
Date: February 2022 | | Page 22-5 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
As part of day-to-day operations, Newmont will continue to perform reviews of the mine plan and consider alternatives to, and variations within, the plan. Alternative scenarios and reviews may be based on ongoing or future mining considerations, evaluation of different potential input factors and assumptions, and corporate directives.
22.13 Recovery Methods
Active loading of the heap leach pads ceased in 2020. The heap leach pad is being recirculated with water while closure plans are under development.
The process plant design was based on a combination of metallurgical testwork, previous study designs, previous operating experience. The design is conventional to the mining industry and has no novel parameters.
The plant will produce variations in recovery due to the day-to-day changes in ore type or combinations of ore type being processed. These variations are expected to trend to the forecast recovery value for monthly or longer reporting periods.
A pyrite leach process circuit treats the zinc rougher tailing from the concentrator for recovery of residual gold and silver, and produces doré bars.
The tertiary precious metals recovery process has not been commissioned because, as of the Report date, the organic carbon grades had not been high enough to operate this circuit. It is expected that organic carbon grades will increase after mid-2022 and the circuit will become operational from that point onward.
22.14 Infrastructure
The majority of the key infrastructure to support the mining activities envisaged in the LOM is in place. Personnel reside in an on-site accommodation complex.
Waste is stored in a series of WRSFs, which have sufficient capacity for the LOM plan. The current WRSF strategy does not consider pit backfilling. All of the WRSFs are located well beyond the crest of the ultimate pit; however, further optimization of the LOM waste storage plan will continue to be examined by Newmont, in an effort to further reduce haulage profiles and resulting unit mining costs.
There is sufficient capacity within the TSF for the current LOM plan.
Within Newmont’s ground holdings, there is sufficient area to allow construction of any additional infrastructure that may be required in the future.
Water supply for the Peñasquito Operations is obtained from groundwater. Newmont continues to monitor the local aquifers to ensure they remain sustainable. A network of monitoring wells was established to monitor water levels and water quality.
Power is currently supplied from the 182 MW power purchase agreement with Saavi Energia, delivered to the mine by the Mexican Federal Electricity Commission. The Federal Electricity Commission continues to provide backup power supply for both planned and unplanned shutdowns from the Saavi Energia power plant.
| | | | | | | | |
Date: February 2022 | | Page 22-6 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
22.15 Market Studies
Newmont has established contracts and buyers for its lead and zinc concentrate, and has a corporate internal marketing group that monitors markets for its concentrate. Together with public documents and analyst forecasts, these data support that there is a reasonable basis to assume that for the LOM plan, that the lead and zinc concentrate will be saleable at the assumed commodity pricing.
Doré is sold on the spot market, by corporate in-house marketing experts. The terms in these contracts are in line with industry standard terms and are consistent with doré sold from other operations. The doré is not subject to product specification requirements.
The largest in-place contracts other than for product sales cover items such as bulk commodities, operational and technical services, mining and process equipment, and administrative support services. Contracts are negotiated and renewed as needed. Contract terms are typical of similar contracts in Mexico that Newmont is familiar with.
22.16 Environmental, Permitting and Social Considerations
Baseline and supporting environmental studies were completed to assess both pre-existing and ongoing site environmental conditions, as well as to support decision-making processes during operations start-up. Characterization studies were completed. Environmental monitoring is ongoing at the Project and will continue over the life of the operations. Key monitoring areas include air, water, noise, wildlife, forest resources and waste management.
The closure costs used in the economic analysis total US$0.8 B.
All major permits and approvals are either in place or Newmont expects to obtain them in the normal course of business. Where permits have specific terms, renewal applications are made of the relevant regulatory authority as required, prior to the end of the permit term.
Public consultation and community assistance and development programs are ongoing.
22.17 Capital Cost Estimates
Capital costs were based on recent prices or operating data and are at a minimum at a pre-feasibility level of confidence, having an accuracy level of ±25% and a contingency range not exceeding 15%.
Capital costs included funding for infrastructure, pit dewatering, development drilling, and permitting as well as miscellaneous expenditures required to maintain production. Mobile equipment re-build/replacement schedules and fixed asset replacement and refurbishment schedules were included. Sustaining capital costs reflected current price trends.
The overall capital cost estimate for the LOM is US$1.1 B.
| | | | | | | | |
Date: February 2022 | | Page 22-7 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
22.18 Operating Cost Estimates
Operating costs were based on actual costs seen during operations and are projected through the LOM plan, and are at a minimum at a pre-feasibility level of confidence, having an accuracy level of ±25% and a contingency range not exceeding 15%.
Historical costs were used as the basis for operating cost forecasts for supplies and services unless there are new contract terms for these items. Labor and energy costs were based on budgeted rates applied to headcounts and energy consumption estimates.
The overall operating cost estimate for the LOM is US$7.4 B.
22.19 Economic Analysis
The NPV8% is US$1.7 B. As the cashflows are based on existing operations where all costs are considered sunk to 1 January 2022, considerations of payback and internal rate of return are not relevant.
22.20 Risks and Opportunities
22.20.1 Risks
The risks associated with the Peñasquito Operations are generally those expected with open pit mining operations and include the accuracy of the resource model, unexpected geological features that cause geotechnical issues, and/or operational impacts.
Other risks noted include:
•Commodity price increases for key consumables such as diesel, electricity, tires and chemicals would negatively impact the stated mineral reserves and mineral resources;
•Labor cost increases or productivity decreases could also impact the stated mineral reserves and mineral resources, or impact the economic analysis that supports the mineral reserves;
•Geotechnical and hydrological assumptions used in mine planning are based on historical performance, and to date historical performance has been a reasonable predictor of current conditions. Any changes to the geotechnical and hydrological assumptions could affect mine planning, affect capital cost estimates if any major rehabilitation is required due to a geotechnical or hydrological event, affect operating costs due to mitigation measures that may need to be imposed, and impact the economic analysis that supports the mineral reserve estimates;
•The mineral resource estimates are sensitive to metal prices. Lower metal prices require revisions to the mineral resource estimates;
•Risk to assumed process recoveries if the organic carbon present cannot be successfully mitigated during processing;
•While there is sufficient space within the TSF for the planned LOM operations, if mineral resources are converted to mineral reserves, additional storage capacity will be required. Any expansion of the TSF is likely to require community relocation;
| | | | | | | | |
Date: February 2022 | | Page 22-8 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
•There are communities that are within the zone of influence of the TSF that can potentially be affected by control failures at the TSF. Newmont continues to study relocation options for these communities, but there is a risk that impacted stakeholders are not amenable to relocation;
•While water supplies are well understood for the LOM operations, supplementary water studies would be required if additional mineral reserves are added to the LOM plan in the future;
•Climate changes could impact operating costs and ability to operate;
•Assumptions that the long-term reclamation and mitigation of the Peñasquito Operations can be appropriately managed within the estimated closure timeframes and closure cost estimates;
•Political risk from challenges to:
◦Mining licenses;
◦Environmental permits;
◦Newmont’s right to operate;
•Changes to assumptions as to governmental tax or royalty rates, such as taxation rate increases or new taxation or royalty imposts.
22.20.2 Opportunities
Opportunities for the Peñasquito Operations include moving the stated mineral resources into mineral reserves through additional drilling and study work. The mineral reserves and mineral resources are based on conservative price estimates for gold, silver, lead, and zinc so upside exists, either in terms of the potential to estimate additional mineral reserves and mineral resources or improved economics should the price used for these metals be increased.
Opportunities include:
•Conversion of some or all of the measured and indicated mineral resources currently reported exclusive of mineral reserves to mineral reserves, with appropriate supporting studies;
•Upgrade of some or all of the inferred mineral resources to higher-confidence categories, such that better-confidence material could be used in mineral reserve estimation;
•Higher metal prices than forecast could present upside sales opportunities and potentially an increase in predicted Project economics;
•Newmont holds a significant ground package around the Peñasquito Operations that retains exploration potential.
22.21 Conclusions
Under the assumptions presented in this Report, the Peñasquito Operations have a positive cash flow, and mineral reserve estimates can be supported.
| | | | | | | | |
Date: February 2022 | | Page 22-9 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
23.0 RECOMMENDATIONS
As the Peñasquito Operations are an operating mine, the QP has no material recommendations to make.
| | | | | | | | |
Date: February 2022 | | Page 23-1 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
24.0 REFERENCES
24.1 Bibliography
Ashby, Z., and Hanson, W.C., 2003: Minera Peñasquito, S.A. De C.V., Preliminary Mineral Resource Estimate: NI 43-101 technical report prepared by SNC Lavalin for Western Silver Corporation, March 2003.
Belanger, M., and Pareja, G., 2014: Peñasquito Polymetallic Operation Zacatecas State Mexico, NI 43-101 Technical Report: NI 43-101 technical report prepared for Goldcorp, effective date 8 January 2014.
Belanger, M., Pareja, G., Chen, E. and Nahan, P., 2011: Peñasquito Polymetallic Operation, Zacatecas State, Mexico, NI 43-101 Technical Report, unpublished NI 43-101 technical report prepared for Goldcorp, effective date 31 December 2011.
Bryson, R.H., Brown, F.H., Rivera, R., and Butcher, M.G., 2009: Peñasquito Project Technical Report, Concepción del Oro District, Zacatecas State, México: unpublished NI 43-101 technical report prepared for Goldcorp, effective date 10 March 2009.
Bryson, R.H., Brown, F.H., Rivera, R., and Ristorcelli, S., 2007: Peñasquito Project Technical Report, Concepción del Oro District, Zacatecas State, México: unpublished NI 43-101 technical report prepared for Goldcorp, effective date 31 December 2007.
Canadian Institute of Mining, Metallurgy and Petroleum (CIM), 2014: CIM Standards for Mineral Resources and Mineral Reserves, Definitions and Guidelines: Canadian Institute of Mining, Metallurgy and Petroleum.
De Rujiter, A., Goodman, S., Pareja, G., and Redmond, D., 2015: Peñasquito Polymetallic Operation Zacatecas State México, NI 43-101 Technical Report: NI 43-101 technical report prepared for Goldcorp, effective date 31 December 2015.
Goldcorp, 2014: Copia de PSQ - Base Case V174 - Send to Vancouver: Excel spreadsheet, December 20, 2013.
Independent Mining Consultants, 2005: Executive Summary of the Technical Report Preliminary Resource Estimate Update for the Peñasco Deposit, Peñasquito Project State of Zacatecas, Mexico: unpublished NI 43-101 technical report prepared by Independent Mining Consultants for Western Silver Corporation, April 2005.
M3 Engineering and Technology Corp., 2004: Western Silver Corporation, Peñasquito Pre-Feasibility Study: unpublished NI 43-101 technical report prepared by Independent Mining Consultants for Western Silver Corporation, April 2004; amended and restated 8 November 2004, further amended and restated 10 December 2004.
Marek, J., Hanks, J.T., Wythes, T.J., Huss, C.E., and Pegnam, M.L., 2005: Peñasquito Feasibility Study Volume I NI 43-101 Technical Report: unpublished NI 43-101 technical report prepared by M3 Engineering and Technology Corp. for Western Silver Corporation, November 2005.
Marlow, J., 2004: Technical Report, Preliminary Resource Estimate, for the Peñasco Deposit Peñasquito Project State of Zacatecas, Mexico: unpublished NI 43-101 technical report prepared for Western Silver Corporation, effective date 3 November 2004.
| | | | | | | | |
Date: February 2022 | | Page 24-1 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
Redmond, D., Goodman, S., Pareja, G., De Ruijter, 2015: Peñasquito Polymetallic Operations, Zacatecas State, México, NI 43-101 Technical Report: NI 43-101 technical report prepared for Goldcorp, effective date 31 December 2015
SNC Lavalin, 2004: Minera Penasquito, S.A. De C.V., Peñasquito Project, Mineral Resource Estimate for Chile Colorado Zone: unpublished NI 43-101 technical report prepared by SNC Lavalin for Western Silver Corporation, March 2004.
Vdovin, V., Pareja, G., and Lind, P., 2018: Peñasquito Polymetallic Operation, Zacatecas State, Mexico, NI 43-101 Technical Report: report prepared for Goldcorp Inc., effective date 30 June, 2018.
Voorhees J.S., Hanks, J.T., Drielick, T.L., Wythes, T.J., Huss, C.E., Pegnam, M.L., and Johnson, J.M., 2008: Peñasquito Feasibility Study, 100,000 Mtpd, NI 43-101 Technical Report: unpublished NI 43-101 technical report prepared by M3 Engineering and Technology Corp. for Glamis Gold Inc., effective date 31 July 2006.
| | | | | | | | |
Date: February 2022 | | Page 24-2 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
24.2 Abbreviations and Symbols
| | | | | |
Abbreviation/Symbol | Term |
AA | atomic absorption |
ARD | acid rock drainage |
CCD | counter-current decantation |
CIM | Canadian Institute of Mining, Metallurgy and Petroleum |
DGPS | differential global positioning system |
FA | fire assay |
G&A | general and administrative |
GPS | global positioning system |
HPGR | high pressure grinding roller |
ICP-AES | inductively coupled plasma atomic emission spectroscopy |
ICP-MS | inductively coupled plasma–mass spectrometry |
ICP-OES | inductively coupled plasma optical emission spectroscopy |
ID2 | inverse distance to the power of two |
IFC | International Finance Corporation |
IP | induced polarization |
LECO | Analyzer designed for wide-range measurement of carbon and sulfur content of mineralization |
LBMA | London Bullion Market Association (now known simply as LBMA) |
LG | Lerchs–Grossmann |
LME | London Metal Exchange |
LOM | life-of-mine |
MXN | Mexican |
NewFields | NewFields Consultants Inc. |
Newmont | Newmont Corporation |
NN | nearest neighbor |
NWF | Northern Well field |
NPSC | near-pit sizing conveyor |
NPV | net present value |
NSR | net smelter return |
QSP | Quartz–sericite–pyrite alteration |
QSPC | Quartz–sericite–pyrite–calcite alteration |
OES | optical emission spectrometry |
PAG | potentially acid-generating |
PC | Pyrite calcite alteration |
PLP | pyrite leach process |
QA/QC | Quality assurance and quality control |
QP | Qualified Person |
RAB | rotary air blast |
RC | reverse circulation |
RQD | rock quality description |
SAG | semi-autogenous grind |
SG | Specific gravity |
SME | Society for Mining, Metallurgy and Exploration |
SRCE | standard reclamation cost estimator |
TSF | tailing storage facility |
US | United States |
US$ | United States dollar |
WRSF | waste rock storage facility |
| | | | | | | | |
Date: February 2022 | | Page 24-3 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
24.3 Glossary of Terms
| | | | | |
Term | Definition |
acid rock drainage/ acid mine drainage | Characterized by low pH, high sulfate, and high iron and other metal species. |
alluvium | Unconsolidated terrestrial sediment composed of sorted or unsorted sand, gravel, and clay that was deposited by water. |
ANFO | A free-running explosive used in mine blasting made of 94% prilled aluminum nitrate and 6% No. 3 fuel oil. |
aquifer | A geologic formation capable of transmitting significant quantities of groundwater under normal hydraulic gradients. |
azimuth | The direction of one object from another, usually expressed as an angle in degrees relative to true north. Azimuths are usually measured in the clockwise direction, thus an azimuth of 90 degrees indicates that the second object is due east of the first. |
ball mill | A piece of milling equipment used to grind ore into small particles. It is a cylindrical shaped steel container filled with steel balls into which crushed ore is fed. The ball mill is rotated causing the balls themselves to cascade, which in turn grinds the ore. |
bullion | Unrefined gold and/or silver mixtures that have been melted and cast into a bar or ingot. |
carbonaceous | Containing graphitic or hydrocarbon species, e.g., in an ore or concentrate; such materials generally present some challenge in processing, e.g., preg-robbing characteristics. |
comminution/crushing/grinding | Crushing and/or grinding of ore by impact and abrasion. Usually, the word "crushing" is used for dry methods and "grinding" for wet methods. Also, "crushing" usually denotes reducing the size of coarse rock while "grinding" usually refers to the reduction of the fine sizes. |
concentrate | The concentrate is the valuable product from mineral processing, as opposed to the tailing, which contains the waste minerals. The concentrate represents a smaller volume than the original ore |
counter-current decantation (CCD) | A process where a slurry is thickened and washed in multiple stages, where clean water is added to the last thickener, and overflows from each thickener are progressively transferred to the previous thickener, countercurrent to the flow of thickened slurry. |
cut-off grade | A grade level below which the material is not “ore” and considered to be uneconomical to mine and process. The minimum grade of ore used to establish reserves. |
data verification | The process of confirming that data was generated with proper procedures, was accurately transcribed from the original source and is suitable to be used for mineral resource and mineral reserve estimation |
density | The mass per unit volume of a substance, commonly expressed in grams/ cubic centimeter. |
diatreme | A volcanic vent or pipe that formed when magma was forced through flat-lying sedimentary rock |
dilution | Waste of low-grade rock which is unavoidably removed along with the ore in the mining process. |
easement | Areas of land owned by the property owner, but in which other parties, such as utility companies, may have limited rights granted for a specific purpose. |
EM | Geophysical method, electromagnetic system, measures the earth's response to electromagnetic signals transmitted by an induction coil |
| | | | | | | | |
Date: February 2022 | | Page 24-4 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
| | | | | |
Term | Definition |
encumbrance | An interest or partial right in real property which diminished the value of ownership, but does not prevent the transfer of ownership. Mortgages, taxes and judgements are encumbrances known as liens. Restrictions, easements, and reservations are also encumbrances, although not liens. |
feasibility study | A feasibility study is a comprehensive technical and economic study of the selected development option for a mineral project, which includes detailed assessments of all applicable modifying factors, as defined by this section, together with any other relevant operational factors, and detailed financial analysis that are necessary to demonstrate, at the time of reporting, that extraction is economically viable. The results of the study may serve as the basis for a final decision by a proponent or financial institution to proceed with, or finance, the development of the project. A feasibility study is more comprehensive, and with a higher degree of accuracy, than a pre-feasibility study. It must contain mining, infrastructure, and process designs completed with sufficient rigor to serve as the basis for an investment decision or to support project financing. |
flotation | Separation of minerals based on the interfacial chemistry of the mineral particles in solution. Reagents are added to the ore slurry to render the surface of selected minerals hydrophobic. Air bubbles are introduced to which the hydrophobic minerals attach. The selected minerals are levitated to the top of the flotation machine by their attachment to the bubbles and into a froth product, called the "flotation concentrate." If this froth carries more than one mineral as a designated main constituent, it is called a "bulk float". If it is selective to one constituent of the ore, where more than one will be floated, it is a "differential" float. |
flowsheet | The sequence of operations, step by step, by which ore is treated in a milling, concentration, or smelting process. |
frother | A type of flotation reagent which, when dissolved in water, imparts to it the ability to form a stable froth |
gangue | The fraction of ore rejected as tailing in a separating process. It is usually the valueless portion, but may have some secondary commercial use |
gravity concentrator | Uses the differences in specific gravity between gold and gangue minerals to realize a separation of the gold from the gangue. |
heap leaching | A process whereby valuable metals, usually gold and silver, are leached from a heap or pad of crushed ore by leaching solutions percolating down through the heap and collected from a sloping, impermeable liner below the pad. |
high pressure grinding rolls (HPGR) | A type of crushing machine consisting of two large studded rolls that rotate inwards and apply a high pressure compressive force to break rocks. |
indicated mineral resource | An 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 term adequate geological evidence means evidence that is sufficient to establish geological and grade or quality continuity with reasonable certainty. 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. |
| | | | | | | | |
Date: February 2022 | | Page 24-5 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
| | | | | |
Term | Definition |
inferred mineral resource | An 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 term limited geological evidence means evidence that is only sufficient to establish that geological and grade or quality continuity is more likely than not. 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. A qualified person must have a reasonable expectation that the majority of inferred mineral resources could be upgraded to indicated or measured mineral resources with continued exploration; and should be able to defend the basis of this expectation before his or her peers. |
initial assessment | An initial assessment is a preliminary technical and economic study of the economic potential of all or parts of mineralization to support the disclosure of mineral resources. The initial assessment must be prepared by a qualified person and must include appropriate assessments of reasonably assumed technical and economic factors, together with any other relevant operational factors, that are necessary to demonstrate at the time of reporting that there are reasonable prospects for economic extraction. An initial assessment is required for disclosure of mineral resources but cannot be used as the basis for disclosure of mineral reserves |
internal rate of return (IRR) | The rate of return at which the Net Present Value of a project is zero; the rate at which the present value of cash inflows is equal to the present value of the cash outflows. |
IP | Geophysical method, induced polarization; used to directly detect scattered primary sulfide mineralization. Most metal sulfides produce IP effects, e.g., chalcopyrite, bornite, chalcocite, pyrite, pyrrhotite |
life of mine (LOM) | Number of years that the operation is planning to mine and treat ore, and is taken from the current mine plan based on the current evaluation of ore reserves. |
measured mineral resource | A 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 term conclusive geological evidence means evidence that is sufficient to test and confirm geological and grade or quality continuity. 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 this section, in sufficient detail to support detailed mine planning and final evaluation of the economic viability of the deposit. |
merger | A voluntary combination of two or more companies whereby both stocks are merged into one. |
Merrill-Crowe circuit | A process which recovers precious metals from solution by first clarifying the solution, then removing the air contained in the clarified solution, and then precipitating the gold and silver from the solution by injecting zinc dust into the solution. The valuable sludge is collected in a filter press for drying and further treatment |
mill | Includes any ore mill, sampling works, concentration, and any crushing, grinding, or screening plant used at, and in connection with, an excavation or mine. |
| | | | | | | | |
Date: February 2022 | | Page 24-6 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
| | | | | |
Term | Definition |
mineral reserve | A 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. The determination that part of a measured or indicated mineral resource is economically mineable must be based on a preliminary feasibility (pre-feasibility) or feasibility study, as defined by this section, conducted by a qualified person applying the modifying factors to indicated or measured mineral resources. Such study must demonstrate that, at the time of reporting, extraction of the mineral reserve is economically viable under reasonable investment and market assumptions. The study must establish a life of mine plan that is technically achievable and economically viable, which will be the basis of determining the mineral reserve. The term economically viable means that the qualified person has determined, using a discounted cash flow analysis, or has otherwise analytically determined, that extraction of the mineral reserve is economically viable under reasonable investment and market assumptions. The term investment and market assumptions includes all assumptions made about the prices, exchange rates, interest and discount rates, sales volumes, and costs that are necessary to determine the economic viability of the mineral reserves. The qualified person must use a price for each commodity that provides a reasonable basis for establishing that the project is economically viable. |
mineral resource | A 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. The term material of economic interest includes mineralization, including dumps and tailings, mineral brines, and other resources extracted on or within the earth’s crust. It does not include oil and gas resources, gases (e.g., helium and carbon dioxide), geothermal fields, and water. When determining the existence of a mineral resource, a qualified person, as defined by this section, must be able to estimate or interpret the location, quantity, grade or quality continuity, and other geological characteristics of the mineral resource from specific geological evidence and knowledge, including sampling; and conclude that there are reasonable prospects for economic extraction of the mineral resource based on an initial assessment, as defined in this section, that he or she conducts by qualitatively applying relevant technical and economic factors likely to influence the prospect of economic extraction. |
net present value (NPV) | The present value of the difference between the future cash flows associated with a project and the investment required for acquiring the project. Aggregate of future net cash flows discounted back to a common base date, usually the present. NPV is an indicator of how much value an investment or project adds to a company. |
net smelter return (NSR) | A defined percentage of the gross revenue from a resource extraction operation, less a proportionate share of transportation, insurance, and processing costs. |
open pit | A mine that is entirely on the surface. Also referred to as open-cut or open-cast mine. |
orogeny | A process in which a section of the earth's crust is folded and deformed by lateral compression to form a mountain range |
ounce (oz) (troy) | Used in imperial statistics. A kilogram is equal to 32.1507 ounces. A troy ounce is equal to 31.1035 grams. |
| | | | | | | | |
Date: February 2022 | | Page 24-7 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
| | | | | |
Term | Definition |
overburden | Material of any nature, consolidated or unconsolidated, that overlies a deposit of ore that is to be mined. |
pebble crushing | A crushing process on screened larger particles that exit through the grates of a SAG mill. Such particles (typically approx. 50 mm diameter) are not efficiently broken in the SAG mill and are therefore removed and broken, typically using a cone crusher. The crushed pebbles are then fed to a grinding mill for further breakage. |
phyllic alteration | Minerals include quartz-sericite-pyrite |
plant | A group of buildings, and especially to their contained equipment, in which a process or function is carried out; on a mine it will include warehouses, hoisting equipment, compressors, repair shops, offices, mill or concentrator. |
potassic alteration | A relatively high temperature type of alteration which results from potassium enrichment. Characterized by biotite, K-feldspar, adularia. |
preg-robbing | A characteristic of certain ores, typically that contain carbonaceous species, where dissolved gold is re-adsorbed by these species, leading to an overall reduction in gold recovery. Such ores require more complex treatment circuits to maximize gold recovery. |
preliminary feasibility study, pre-feasibility study | A preliminary feasibility study (prefeasibility study) is a comprehensive study of a range of options for the technical and economic viability of a mineral project that has advanced to a stage where a qualified person has determined (in the case of underground mining) a preferred mining method, or (in the case of surface mining) a pit configuration, and in all cases has determined an effective method of mineral processing and an effective plan to sell the product. A pre-feasibility study includes a financial analysis based on reasonable assumptions, based on appropriate testing, about the modifying factors and the evaluation of any other relevant factors that are sufficient for a qualified person to determine if all or part of the indicated and measured mineral resources may be converted to mineral reserves at the time of reporting. The financial analysis must have the level of detail necessary to demonstrate, at the time of reporting, that extraction is economically viable |
probable mineral reserve | A probable mineral reserve is the economically mineable part of an indicated and, in some cases, a measured mineral resource. For a probable mineral reserve, the qualified person’s confidence in the results obtained from the application of the modifying factors and in the estimates of tonnage and grade or quality is lower than what is sufficient for a classification as a proven mineral reserve, but is still sufficient to demonstrate that, at the time of reporting, extraction of the mineral reserve is economically viable under reasonable investment and market assumptions. The lower level of confidence is due to higher geologic uncertainty when the qualified person converts an indicated mineral resource to a probable reserve or higher risk in the results of the application of modifying factors at the time when the qualified person converts a measured mineral resource to a probable mineral reserve. A qualified person must classify a measured mineral resource as a probable mineral reserve when his or her confidence in the results obtained from the application of the modifying factors to the measured mineral resource is lower than what is sufficient for a proven mineral reserve. |
propylitic | Characteristic greenish color. Minerals include chlorite, actinolite and epidote. Typically contains the assemblage quartz–chlorite–carbonate |
proven mineral reserve | A proven mineral reserve is the economically mineable part of a measured mineral resource. For a proven mineral reserve, the qualified person has a high degree of confidence in the results obtained from the application of the modifying factors and in the estimates of tonnage and grade or quality. A proven mineral reserve can only result from conversion of a measured mineral resource. |
| | | | | | | | |
Date: February 2022 | | Page 24-8 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
| | | | | |
Term | Definition |
qualified person | A qualified person is an individual who is a mineral industry professional with at least five years of relevant experience in the type of mineralization and type of deposit under consideration and in the specific type of activity that person is undertaking on behalf of the registrant; and an eligible member or licensee in good standing of a recognized professional organization at the time the technical report is prepared. For an organization to be a recognized professional organization, it must: (A)Be either: (1)An organization recognized within the mining industry as a reputable professional association, or (2)A board authorized by U.S. federal, state or foreign statute to regulate professionals in the mining, geoscience or related field; (B)Admit eligible members primarily on the basis of their academic qualifications and experience; (C)Establish and require compliance with professional standards of competence and ethics; (D)Require or encourage continuing professional development; (E)Have and apply disciplinary powers, including the power to suspend or expel a member regardless of where the member practices or resides; and; (F)Provide a public list of members in good standing. |
reclamation | The restoration of a site after mining or exploration activity is completed. |
refining | A high temperature process in which impure metal is reacted with flux to reduce the impurities. The metal is collected in a molten layer and the impurities in a slag layer. Refining results in the production of a marketable material. |
resistivity | Observation of electric fields caused by current introduced into the ground as a means of studying earth resistivity in geophysical exploration. Resistivity is the property of a material that resists the flow of electrical current |
rock quality designation (RQD) | A measure of the competency of a rock, determined by the number of fractures in a given length of drill core. For example, a friable ore will have many fractures and a low RQD. |
royalty | An amount of money paid at regular intervals by the lessee or operator of an exploration or mining property to the owner of the ground. Generally based on a specific amount per tonne or a percentage of the total production or profits. Also, the fee paid for the right to use a patented process. |
run-of-mine (ROM) | Rehandle where the raw mine ore material is fed into the processing plant’s system, usually the crusher. This is where material that is not direct feed from the mine is stockpiled for later feeding. Run-of-mine relates to the rehandle being for any mine material, regardless of source, before entry into the processing plant’s system. |
semi-autogenous grinding (SAG) | A method of grinding rock into fine powder whereby the grinding media consists of larger chunks of rocks and steel balls. |
specific gravity | The weight of a substance compared with the weight of an equal volume of pure water at 4°C. |
tailings | Material rejected from a mill after the recoverable valuable minerals have been extracted. |
triaxial compressive strength | A test for the compressive strength in all directions of a rock or soil sample |
uniaxial compressive strength | A measure of the strength of a rock, which can be determined through laboratory testing, and used both for predicting ground stability underground, and the relative difficulty of crushing. |
| | | | | | | | |
Date: February 2022 | | Page 24-9 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
25.0 RELIANCE ON INFORMATION PROVIDED BY THE REGISTRANT
25.1 Introduction
The QP fully relied on the registrant for the information used in the areas noted in the following sub-sections. The QP considers it reasonable to rely on the registrant for the information identified in those sub-sections, for the following reasons:
•The registrant has been owner and operator of the mining operations more than 10 years;
•The registrant has employed industry professionals with expertise in the areas listed in the following sub-sections;
•The registrant has a formal system of oversight and governance over these activities, including a layered responsibility for review and approval;
•The registrant has considerable experience in each of these areas.
25.2 Macroeconomic Trends
•Information relating to inflation, interest rates, discount rates, exchange rates, and taxes was obtained from the registrant.
This information is used in the economic analysis in Chapter 19. It supports the assessment of reasonable prospects for economic extraction of the mineral resource estimates in Chapter 11, and inputs to the determination of economic viability of the mineral reserve estimates in Chapter 12.
25.3 Markets
•Information relating to market studies/markets for product, market entry strategies, marketing and sales contracts, product valuation, product specifications, refining and treatment charges, transportation costs, agency relationships, material contracts (e.g., mining, concentrating, smelting, refining, transportation, handling, hedging arrangements, and forward sales contracts), and contract status (in place, renewals), was obtained from the registrant.
This information is used in the economic analysis in Chapter 19. It supports the assessment of reasonable prospects for economic extraction of the mineral resource estimates in Chapter 11, and inputs to the determination of economic viability of the mineral reserve estimates in Chapter 12.
25.4 Legal Matters
•Information relating to the corporate ownership interest, the mineral tenure (concessions, payments to retain property rights, obligations to meet expenditure/reporting of work conducted), surface rights, water rights (water take allowances), royalties, encumbrances,
| | | | | | | | |
Date: February 2022 | | Page 25-1 |
| | | | | |
Peñasquito Operations Mexico Technical Report Summary | |
| |
easements and rights-of-way, violations and fines, permitting requirements, and the ability to maintain and renew permits was obtained from the registrant.
This information is used in support of the property description and ownership information in Chapter 3, the permitting and mine closure descriptions in Chapter 17, and the economic analysis in Chapter 19. It supports the reasonable prospects of economic extraction for the mineral resource estimates in Chapter 11, and the assumptions used in demonstrating economic viability of the mineral reserve estimates in Chapter 12.
25.5 Environmental Matters
•Information relating to baseline and supporting studies for environmental permitting, environmental permitting and monitoring requirements, ability to maintain and renew permits, emissions controls, closure planning, closure and reclamation bonding and bonding requirements, sustainability accommodations, and monitoring for and compliance with requirements relating to protected areas and protected species was obtained from the registrant.
This information is used when discussing property ownership information in Chapter 3, the permitting and closure discussions in Chapter 17, and the economic analysis in Chapter 19. It supports the reasonable prospects of economic extraction for the mineral resource estimates in Chapter 11, and the assumptions used in demonstrating economic viability of the mineral reserve estimates in Chapter 12.
25.6 Stakeholder Accommodations
•Information relating to social and stakeholder baseline and supporting studies, hiring and training policies for workforce from local communities, partnerships with stakeholders (including national, regional, and state mining associations; trade organizations; fishing organizations; state and local chambers of commerce; economic development organizations; non-government organizations; and, state and federal governments), and the community relations plan was obtained from the registrant.
This information is used in the social and community discussions in Chapter 17, and the economic analysis in Chapter 19. It supports the reasonable prospects of economic extraction for the mineral resource estimates in Chapter 11, and the assumptions used in demonstrating economic viability of the mineral reserve estimates in Chapter 12.
25.7 Governmental Factors
•Information relating to taxation and royalty considerations at the Project level, monitoring requirements and monitoring frequency, bonding requirements, and violations and fines was obtained from the registrant.
This information is used in the discussion on royalties and property encumbrances in Chapter 3, the monitoring, permitting and closure discussions in Chapter 17, and the economic analysis in Chapter 19. It supports the reasonable prospects of economic extraction for the mineral resource estimates in Chapter 11, and the assumptions used in demonstrating economic viability of the mineral reserve estimates in Chapter 12.
| | | | | | | | |
Date: February 2022 | | Page 25-2 |
Boddington Operations
Western Australia
Technical Report Summary
Report current as of:
December 31, 2021
Qualified Person:
Mr. Donald Doe, RM SME.
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
NOTE REGARDING FORWARD-LOOKING INFORMATION
This Technical Report Summary contains forward-looking statements within the meaning of the U.S. Securities Act of 1933 and the U.S. Securities Exchange Act of 1934 (and the equivalent under Canadian securities laws), that are intended to be covered by the safe harbor created by such sections. Such forward-looking statements include, without limitation, statements regarding Newmont’s expectation for its mines and any related development or expansions, including estimated cash flows, production, revenue, EBITDA, costs, taxes, capital, rates of return, mine plans, material mined and processed, recoveries and grade, future mineralization, future adjustments and sensitivities and other statements that are not historical facts.
Forward-looking statements address activities, events, or developments that Newmont expects or anticipates will or may occur in the future and are based on current expectations and assumptions. Although Newmont’s management believes that its expectations are based on reasonable assumptions, it can give no assurance that these expectations will prove correct. Such assumptions, include, but are not limited to: (i) there being no significant change to current geotechnical, metallurgical, hydrological and other physical conditions; (ii) permitting, development, operations and expansion of operations and projects being consistent with current expectations and mine plans, including, without limitation, receipt of export approvals; (iii) political developments in any jurisdiction in which Newmont operates being consistent with its current expectations; (iv) certain exchange rate assumptions being approximately consistent with current levels; (v) certain price assumptions for gold, copper, silver, zinc, lead and oil; (vi) prices for key supplies being approximately consistent with current levels; and (vii) other planning assumptions.
Important factors that could cause actual results to differ materially from those in the forward-looking statements include, among others, risks that estimates of mineral reserves and mineral resources are uncertain and the volume and grade of ore actually recovered may vary from our estimates, risks relating to fluctuations in metal prices; risks due to the inherently hazardous nature of mining-related activities; risks related to the jurisdictions in which we operate, uncertainties due to health and safety considerations, including COVID-19, uncertainties related to environmental considerations, including, without limitation, climate change, uncertainties relating to obtaining approvals and permits, including renewals, from governmental regulatory authorities; and uncertainties related to changes in law; as well as those factors discussed in Newmont’s filings with the U.S. Securities and Exchange Commission, including Newmont’s latest Annual Report on Form 10-K for the period ended December 31, 2021, which is available on newmont.com.
Newmont does not undertake any obligation to release publicly revisions to any “forward-looking statement,” including, without limitation, outlook, to reflect events or circumstances after the date of this document, or to reflect the occurrence of unanticipated events, except as may be required under applicable securities laws. Investors should not assume that any lack of update to a previously issued “forward-looking statement” constitutes a reaffirmation of that statement. Continued reliance on “forward-looking statements” is at investors’ own risk.
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
CONTENTS
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
TABLES
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
FIGURES
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
1.0 EXECUTIVE SUMMARY
1.1 Introduction
This technical report summary (the Report) was prepared for Newmont Corporation (Newmont) on the Boddington Operations (Boddington Operations or the Project) located in southern Western Australia (WA).
1.2 Terms of Reference
The Report was prepared to be attached as an exhibit to support mineral property disclosure, including mineral resource and mineral reserve estimates, for the Boddington Operations in Newmont’s Form 10-K for the year ending December 31, 2021.
Mineral resources and mineral reserves are reported for the North and South pits (also referred to as Wandoo North and Wandoo South). Mineral reserves are also estimated for material in stockpiles.
Gold operations were conducted in two phases. The initial oxide operations, a combination of open pit and underground mining, ran from 1987–2001. The current operations commenced in 2009 from open pit sources.
Unless otherwise indicated, all financial values are reported in Australian dollars (AU$). Unless otherwise indicated, the metric system is used in this Report. Mineral resources and mineral reserves are reported using the definitions in Regulation S–K 1300 (SK1300), under Item 1300. The Report uses US English. The Report contains forward-looking information; refer to the note regarding forward-looking information at the front of the Report.
1.3 Property Setting
The Boddington Operations are located about 130 km southeast of the city of Perth and 17 km northwest of the township of Boddington, and are accessed via a sealed road from the township. Perth is the main source of supplies, and has a large, specialized infrastructure for mining support. Workers commute from Boddington and surrounding settlements to the mine site.
The climate is Mediterranean, with hot, dry summers and cool, wet winters. Mining operations are conducted year-round.
The mine is located on the Darling Plateau in an area of deeply weathered, undulating landscape that ranges from 200–500 meters Relative Level (mRL). Local relief varies by about 100 m, with shallow valley floors adjacent to broadly convex hills.
The mining leases are located largely on private forested land typical of the eastern Jarrah (a type of eucalyptus) forest.
1.4 Ownership
The majority of the Boddington Operations area is located within the original boundaries of a single large tenement (M258SA) granted under a State Agreement known as the Worsley State
| | | | | | | | |
Date: February, 2022 | | Page 1-1 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Agreement. M258SA is held by the Worsley Joint Venture (Worsley JV) and permits the mining of bauxite only.
In the early 1980s, the Worsley JV discovered gold mineralization at Boddington. The Worsley State Agreement was amended to enable the granting of all mineral leases under the Mining Act of Western Australia 1978 within the boundaries of M258SA. The Worsley JV established a new joint venture to exploit the gold mineralization, the Boddington Gold Mine Joint Venture (BGMJV). The relationship between the bauxite/alumina operations and the gold operations was regulated under a cross-operation agreement which, in a restated form, continues as of the Report date. The paramount principle regulating the relationship between the Worsley JV and the BGMJV was that bauxite and bauxite operations were to have priority over all other minerals within an area (the Common Area) that was defined within the boundaries of M258SA. This interpretation remains current as of the Report date.
Ownership of the BGMJV changed over time so that the participants in the Worsley JV were no longer the same as the BGMJV participants. In order to accommodate the transfer of ownership to incoming BGMJV participants while maintaining bauxite rights, a series of transactions were entered into that resulted in the present structure whereby the BGMJV participants sublease the mining leases on which the gold mineralization is located.
Since 2009, Newmont has had 100% ownership of the BGMJV. The current parties to the BGMJV are Newmont Boddington Pty Ltd (66⅔%) and Saddleback Investments Pty Ltd (Saddleback; (33⅓%). Both companies are indirectly-wholly owned Newmont subsidiaries.
1.5 Mineral Tenure, Surface Rights, Water Rights, Royalties and Agreements
Newmont has an interest in a total of 89 tenements in the Boddington area The total granted area is approximately 21,249 ha and the under-application area is approximately 60,767 ha.
The actual mining area is covered by the following 13 WA Mining Act leases: M70/21–26, M70/564, M70/799, M70/1031, G70/215 and G70/218–219, and M264SA. Mining leases M70/21–26 and M70/799 are the key tenements under which gold mining activity is concentrated.
A total of 26 of the mining tenements are at an application stage. Under the Mining Act of Western Australia 1978, Mining Leases are granted for 21 years and are renewable. Five mining leases (M70/21–25) were renewed in March 2007 for a 21-year term.
Newmont has an automatic right to be granted new subleases when the tenements are renewed. The Worsley JV may renew the mining leases. Through direct lease holding and sub-lease arrangements with the Worsley JV, Newmont holds the rights to minerals other than bauxite in proportion to the Newmont ownership percentages.
The Boddington Operations have freehold ownership of all the eastern and central areas of operations. Within this freehold land are all the existing tailings storage facility (TSF) areas, the plant site, almost all of the area of the main open pit from the former oxide operation, and all but one of the smaller satellite open pits from the 1987–2001 operation. The western portion of the operational area is outside the freehold land is Crown land covered by native forest. Mining operations can be conducted in this area but with certain restrictions imposed by the State Government through the 1978 Mining Act that are applicable to forested Crown lands.
| | | | | | | | |
Date: February, 2022 | | Page 1-2 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
The Boddington Operations area was previously subject to a land claim registered under the Native Title Act and referred to as the Gnaala Karla Booja Claim. This claim has now been settled (The South West Native Title Settlement) and the settlement between the Western Australian Government and the claimant group became effective in January 2021.
Production royalties on copper, gold, and silver are payable to the WA government and are included in the net smelter return (NSR) cut-off determination.
1.6 Geology and Mineralization
The deposit style is still somewhat controversial. Features consistent with porphyry-style mineralization, classic orogenic shear zones, and intrusion-related gold–copper–bismuth mineralization, are all recognized, giving rise to a variety of genetic interpretations.
The Boddington deposit is hosted within the Wells Formation in the Saddleback Greenstone Belt, which lies in the southeastern corner of the Archaean Yilgarn Craton. The deposit lies within a 6 km strike length of the Wells Formation. For descriptive purposes the deposit is subdivided at approximately 12200 N into two main centers of bedrock mineralization, referred to as Wandoo North (North Pit) and Wandoo South (South Pit). Most of the primary mineralization is hosted within intermediate to felsic intrusive, volcanic, and volcano–sedimentary rocks. The deepest mineralization intercept is at approximately 1,219 m. The laterite zone consists of 1–10 m of topsoil and loose gravel, underlain by 1–2 m of ferruginous duricrust, and a basal zone of 1–10 m of gibbsitic bauxite with goethite, hematite and minor kaolinite. The saprolite zone, 25–80 m thick, typically consists of mottled and ferruginous kaolinitic clays, with preserved rock textures.
Two mineralization stages were recognized. The earliest phase consists of widespread silica–biotite alteration and complex quartz + albite + molybdenite ± muscovite ± clinozoisite ± chalcopyrite veins, all of which are variably deformed by ductile shear zones. Gold in the laterite zones occurs in association with iron and aluminum hydroxides. Gold in the saprolite is hosted in primary quartz veins, in clays immediately adjacent to mineralized quartz veins, and in secondary, shallow-dipping, goethitic horizons. Saprock mineralization reflects the mineralization distribution in the underlying bedrock. Bedrock gold mineralization is hosted in veins, lenses and stockworks. Chalcopyrite and pyrrhotite are the dominant sulfides, with lesser pyrite, sphalerite, cubanite, cobaltite, arsenopyrite, pentlandite, covellite, bismuthinite, digenite, marcasite and galena.
1.7 History and Exploration
Exploration from 1975–2002, prior to Newmont’s Project interest, was conducted by the Geological Survey of Western Australia, Reynolds Australia Mines, the BGMJV, and Alcoa of Australia Limited. Work conducted included geochemical prospecting and sampling, geological mapping, airborne and ground geophysical surveys, drill testing, mineral resource and ore (mineral) reserve estimates, mining studies, environmental studies, applications for environmental approvals, open pit and underground mining.
Newmont became a party to the BGMJV in 2002, and work conducted by Newmont and the BGMJV since that date included geological and structural mapping, a deep sensing geochemical program, airborne and ground geophysical surveys, drill testing, mineral resource
| | | | | | | | |
Date: February, 2022 | | Page 1-3 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
and ore (mineral) reserve estimates, mining studies, environmental studies, permit applications, and open pit mining.
Newmont is currently using district-scale datasets as exploration tools to identify additional mineralization within the Saddleback Greenstone Belt. The datasets are assisting with recognizing new belt-scale lineaments and felsic intrusions, similar to the monzogranite possibly associated with gold mineralization at Boddington, which could host additional Boddington-style mineralization. A number of possible cutbacks were identified adjacent to the current mine plan that may represent upside potential for the operations if these areas can be included in the life-of-mine (LOM) plan.
1.8 Drilling and Sampling
1.8.1 Drilling
Approximately 159,490 drill holes were completed by December 31, 2021, for about 3.80 Mm of drilling. Drill methods included core, reverse circulation (RC), aircore (AC), rotary air blast (RAB) and vacuum. Drilling that supports the 2021 mineral resource and mineral reserve estimates consists of core and RC drill holes.
Blast holes were drilled for drill-and-blast purposes on a 5.2 x 5.2 m pattern for ore and 5.7 x 5.7 m pattern for waste.
Standardized logging procedures and software are used to record geological and geotechnical information. Core recoveries are typically 100%. Core and RC collars are recorded using differential global positioning system (DGPS) instruments. Downhole survey instruments used include single shot Eastman, single or multishot Reflex and north-seeking gyro tools. Downhole surveys were taken on spacings ranging from 30–50 m.
1.8.2 Hydrogeology
Groundwater monitoring was completed via a network of monitoring bores and grouted multiple vibrating wire piezometer pore pressure monitoring bores, covering all areas of the active mine site (including waste rock storage facilities (WRSFs) and TSF areas) and the regional areas peripheral to the mine operations.
Complimenting the groundwater monitoring programs are extensive surface water sampling programs focused on regional, mining (WRSFs and drainage), TSFs, and processing areas. The surface water samples are sent to the same laboratory as the groundwater samples with monitoring of water quality variables specific to the risk associated with the sample location. As required, corporate subject matter experts and/or third party consultants undertake specialized hydrological/geotechnical evaluations.
To the Report date, the hydrogeological data collection programs have provided data suitable for use in the mining operations, and have supported the assumptions used in the active pits.
1.8.3 Geotechnical
Geotechnical systems are implemented and maintained to monitor slope and pit wall deformation. Geotechnical data are collected where considered necessary to provide additional
| | | | | | | | |
Date: February, 2022 | | Page 1-4 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
information and to verify ground conditions in the vicinity of the open pits and WRSFs. Core drilling methods are used to collect soil and or rock core. Materials encountered are logged and sampled are selected and recovered for laboratory testing where required.
In addition to information gathered during core drilling, geological structures are mapped and documented continuously as mining progresses in the open pits. This is aided through use of geo-referenced photogrammetry and high-definition point cloud scanning that is used to create digital references of structures modelled.
The geological hard rock setting at the Boddington Operations is well understood and displays consistency in the various open pits located on site. Additional testing continues to confirm the consistency of material strengths and parameters.
1.8.4 Sampling and Assay
RC and core samples were typically collected on 1–2 m intervals. A single sample is taken from blastholes.
Bulk density values were collected primarily using the water immersion method. Approximately 10% of the samples were sent to an independent offsite laboratory for check measurements.
Independent laboratories used for sample preparation and analysis included Classic Comlabs; Genalysis, now part of the Intertek Group (Intertek Genalysis); Amdel, Kalassay, Analabs, UltraTrace Geoanalytical Laboratories (Ultratrace) (all now part of the Bureau Veritas Group), and Australian Assay Laboratories (AAL) in Perth, AAL in Boddington. Since 2006, the primary and check laboratories, Intertek Genalysis and Bureau Veritas, have held ISO/IEC 17025 accreditations for selected analytical techniques. The Boddington mine laboratory, operated by AAL and Amdel, was used from 1985–2001.
Various sample preparation crushing and pulverizing protocols were used since the 1980s, depending on the laboratory. Recent protocols saw Intertek Genalysis crushing to a nominal P90 passing 3 mm and pulverizing to a nominal 95% minus 100 µm; Ultratrace crushing to 2.8 mm and pulverizing to a nominal 95% passing 90 µm; and Bureau Veritas Kalassay crushing to a nominal 95% passing 3 mm and pulverizing to a nominal 95% passing 90 µm.
Analytical methods depended on the sample type and laboratory. For RC and core samples prior to 2006, analysis of gold was by fire assay with either AAS or inductively-coupled plasma atomic emission spectroscopy (ICP-AES). Copper analysis was by either single acid digestion or three-acid digestion followed by AAS. Post 2006, gold was assayed using fire assay with an AAS finish, and a multi-element suite was determined using four-acid digest with either an ICP optical emission spectroscopy (OES) or ICP mass spectrometry (MS) finish. Multi-element determination was not routinely performed prior to 2006, but rather performed on selected drill holes as part of detailed geological investigations.
1.8.5 Quality Assurance and Quality Control
A quality assurance and quality control (QA/QC) program was in place from 1989 onward. The type and nature of samples used in the program varied over time. Since 2006, standards and blanks were submitted randomly in the sample stream prior to submission to the assay laboratory. Standards were both commercially-prepared and sourced from Boddington mineralization.
| | | | | | | | |
Date: February, 2022 | | Page 1-5 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
The grade control QA/QC process has been in place since 2008.
Results are regularly monitored. The QA/QC programs adequately address issues of precision, accuracy and contamination.
1.9 Data Verification
Newmont personnel regularly visit the laboratories that process Newmont samples to inspect sample preparation and analytical procedures.
The database that supports mineral resource and mineral reserve estimates is checked using electronic data scripts and triggers. Newmont also conducted a number of internal data verification programs since obtaining its Project interest. Newmont conducts internal audits, termed Reserve and Resource Review (3R) audits, of all its operations. The most recent Boddington Operations 3R audits were conducted in 2012, 2014, and 2019. The 2019 3R audit found that the Boddington Operations were generally adhering to Newmont’s internal standards and guidelines with respect to the estimation of mineral resources and mineral reserves.
Data verification was performed by external consultants or BGMJV partners in support of mine development and operations. Many of the audits were conducted prior to the commencement of the current mining operation in 2009 to ensure that the best possible database, geological interpretations, block models, and resource estimates were available to support investment decisions.
The QP receives and reviews monthly reconciliation reports from the mine site. These reports include the industry standard reconciliation factors for tonnage, grade and metal. Through the review of these reconciliation factors the QP is able to ascertain the quality and accuracy of the data and its suitability for use in the assumptions underlying the mineral resource and mineral reserve estimates.
1.10 Metallurgical Testwork
During feasibility-stage studies from 1997–2003, several programs of metallurgical testwork were completed on the Boddington deposit. These supported the initial mining phase. A second phase of testwork was conducted in 2008, and a third phase in 2017. The post-feasibility testwork was primarily conducted at AMMTEC in Perth, now ALS Metallurgy.
Samples selected for metallurgical testing during feasibility and development studies were representative of the various styles of mineralization within the different deposits. Samples were selected from a range of locations within the deposit zones. Sufficient samples were taken and tests were performed using sufficient sample mass for the respective tests undertaken.
Work completed included mineralogy, comminution and high-pressure grind–roll (HPGR) testwork, Bond ball mill, Bond rod mill work index, and abrasion index tests, flotation and leach testwork locked cycle flotation test, scavenger tail leach, cleaner scavenger tail leach); flotation tailings cyanidation testwork; determination of thickening and slurry pumping characteristics; rheology; tailings characterization; and oxygen addition.
Recovery models were developed using known ore parameters to predict plant recovery. In these models, the throughput rate is fixed and the grind size is allowed to vary with ore hardness, resulting in recovery differences in each of the eight geometallurgical domains. The
| | | | | | | | |
Date: February, 2022 | | Page 1-6 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
gold and copper recovery models for the mill are based on head grade. The forecast LOM gold recovery is 85% and the forecast LOM copper recovery is 82%. These forecasts do not include the application of recovery degradation to long-term stockpiles of medium-grade ore. Gold recovery is discounted by 3% and copper recovery is discounted by 6% to account for recovery degradation in the business plan. These degradation assumptions were verified by an ongoing stockpile oxidation testwork program.
Since commissioning in 2009, the operation has actively managed the arsenic level in plant feed and, through concentrate blending techniques, controlled the level in copper concentrate shipments to below the penalty rate trigger, hence no penalties were incurred to the Report date. Bismuth is closely associated with gold in the Wandoo ores; however, so it has resulted in penalty levels being exceeded, particularly in the first two years of operation (2009–2011). Most of the high bismuth ores have been processed, resulting in very low to no penalty charges being incurred since 2012.
Alumina remains the largest penalty element present in the copper concentrate, with shipments regularly exposed to a penalty adjustment. However, at 4–5% Al2O3 the levels are not far off the trigger point of 3% in most contracts and a modification to the process was made during Q1 2019 with the introduction of the cleaner–scalper column which reduces the non-sulfide gangue (i.e., Al2O3) in the concentrate and improves the grade of the concentrate as a result.
1.11 Mineral Resource Estimation
1.11.1 Estimation Methodology
The close-out date for the sample database used in mineral resource estimation was August 13 2021, with the resource model dated at October 1, 2021. Exploratory data analysis included statistical reviews and contact analysis to determine estimation domain boundaries.
Six models were constructed: geology, gold, copper, in-situ bulk density (density), deleterious/secondary elements (arsenic, bismuth, molybdenum and sulfur), geotechnical, structural and acid rock drainage.
Density values were interpolated using ordinary kriging (OK) to provide block estimates when sufficient data were available. Where insufficient data were available, an assigned density was used.
All assay data were composited to 12 m lengths downhole. High-grade and outlier grade cuts were applied to each of the gold, copper, arsenic, bismuth, molybdenum and sulfur domains. Spatial variability of the grades for gold, copper, arsenic, bismuth, molybdenum and sulfur was modeled through directional variography of capped 12 m composites.
Ordinary kriged estimates for gold, copper, sulfur, arsenic, molybdenum and bismuth and density were conducted in a separate block model with a parent block size of 10 x 20 x 12 m with sub-blocking to 5 x 5 x 6 m. The final block size used in the resource block model was a regularized size of 20 x 20 x 12 m to match the current selective mining unit. Estimation allowed for a minimum of six samples, a maximum of eight, with a maximum of two samples used per drill hole, and a minimum of three and maximum of eight drill holes per block.
Grade dilution was applied due to unavoidable mining of small dolerite bodies. Modifying factors were applied to sulfur and copper, based on historical plant reconciliation data.
| | | | | | | | |
Date: February, 2022 | | Page 1-7 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Validation used Newmont-standard methods, including a combination of visual checks, swath plots, global statistical bias checks against input data, alternate estimation methods and reconciliation with historical mine/plant performance. The validation procedures indicated that the geology and resource models used are acceptable to support the mineral resource estimation.
Mineral resource classification was undertaken based primarily on drill spacing and number of drill holes used in the estimate. Mineral resources were classified as measured, indicated, and inferred. A quantitative assessment of geological risk was undertaken using Newmont-standard methods and applied on a block by block basis. Primary risks to resource quality include quantity and spacings of drill data, geological knowledge, geological interpretation and grade estimates. All identified risks are within acceptable tolerances with associated management plans.
Mineral resources considered amenable to open pit mining methods are reported within a mine design. Commodity prices used in resource estimation are based on long-term analyst and bank forecasts, supplemented with research by Newmont’s internal specialists. The estimated timeframe used for the price forecasts is the 14-year LOM that supports the mineral reserve estimates. The cut-off grade is defined by a revenue cut-off to account for both copper and gold revenue with two product streams, gold doré and copper concentrate. The block revenue is calculated on a net smelter return (NSR) basis, which is the dollar return expected from the sale of the concentrate produced from a tonne of in situ material. The mine plan is based on a 42 Mt/a mill throughput. The schedule was developed at an NSR cut-off of AU$17.34/t, incorporating the processing cost, metallurgical recovery, incremental ore mining costs, process sustaining capital and tailings dam related rehabilitation costs. The net revenue calculation assumes a gold price of US$1,400/oz or AU$1,867/oz, and a copper price of US$3.25/lb or AU$4.33/lb. The assumed exchange rate for mineral reserves was 0.75 US$:AU$. Mineral resources are reported above an NSR cut-off of AU$17.34/t.
1.11.2 Mineral Resource Statement
Mineral resources are reported using the mineral resource definitions set out in SK1300 and are current as at December 31, 2021. The reference point for the estimate is in situ. Mineral resources are reported exclusive of those mineral resources converted to mineral reserves. Mineral resources that are not mineral reserves do not have demonstrated economic viability.
The mineral resource estimates for the Boddington Operations are summarized in Table 1-1 (measured and indicated; gold) and Table 1-2 (inferred; gold) and Table 1-3 (measured and indicated; copper) and Table 1-4 (inferred; copper).
1.11.3 Factors That May Affect the Mineral Resource Estimate
Factors which may affect the mineral resource estimates include: metal price assumptions; changes to the assumptions used to generate the NSR cut-off; changes to design parameter assumptions that pertain to the conceptual pit design that constrain the mineral resources, including changes to geotechnical, mining and metallurgical recovery assumptions, and changes to royalties levied and any other relevant parameters that are included in and impact the NSR cut-off determination; changes in interpretations of mineralization geometry and continuity of mineralization zones; changes to the dilution skin percentages used for large
| | | | | | | | |
Date: February, 2022 | | Page 1-8 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
dolerite dykes; and assumptions as to the continued ability to access the site, retain mineral and surface rights titles, maintain the operation within environmental and other regulatory permits, and retain the social license to operate.
1.12 Mineral Reserve Estimation
1.12.1 Estimation Methodology
Measured and indicated mineral resources were converted to mineral reserves. Mineral reserves were estimated assuming open pit mining, and the use of conventional Owner-operated equipment. All Inferred blocks are classified as waste in the cashflow analysis that supports mineral reserve estimation.
Table 1-1: Measured and Indicated Mineral Resource Statement (Gold)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Measured Mineral Resources | Indicated Mineral Resources | Measured and Indicated Mineral Resources |
Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) |
Boddington | 96,200 | 0.53 | 1,640 | 180,500 | 0.54 | 3,110 | 276,700 | 0.53 | 4,750 |
Table 1-2: Inferred Mineral Resource Statement (Gold)
| | | | | | | | | | | |
Area | Inferred Mineral Resources |
Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) |
Boddington | 3,300 | 0.5 | 50 |
Table 1-3: Measured and Indicated Mineral Resource Statement (Copper)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Measured Mineral Resources | Indicated Mineral Resources | Measured and Indicated Mineral Resources |
Tonnage (x 1,000 t) | Grade (Cu %) | Cont. Copper (M lbs) | Tonnage (x 1,000 t) | Grade (Cu %) | Cont. Copper (M lbs) | Tonnage (x 1,000 t) | Grade (Cu %) | Cont. Copper (M lbs) |
Boddington | 96,200 | 0.11 | 220 | 180,500 | 0.11 | 450 | 276,700 | 0.11 | 670 |
Table 1-4: Inferred Mineral Resource Statement (Copper)
| | | | | | | | | | | |
Area | Inferred Mineral Resources |
Tonnage (x 1,000 t) | Grade (Cu %) | Cont. Copper (M lbs) |
Boddington | 3,300 | 0.1 | 10 |
Notes to accompany mineral resource tables:
1.Mineral resources are current as at December 31, 2021, and are reported using the definitions in SK1300 on a 100% basis. The Qualified Person responsible for the estimate is Mr. Donald Doe, RM SME, Group Executive, Reserves, a Newmont employee.
2.The reference point for the mineral resources is in situ.
| | | | | | | | |
Date: February, 2022 | | Page 1-9 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
3.Mineral Resources are reported exclusive of mineral reserves. Mineral resources that are not mineral reserves do not have demonstrated economic viability.
4.Mineral resources that are potentially amenable to open pit mining methods are constrained within a designed pit . Parameters used are summarized in Table 11-3.
5.Tonnages are metric tonnes rounded to the nearest 100,000. Gold grade is rounded to the nearest 0.01 gold grams per tonne. Copper grade is reported as a %. Gold ounces and copper pounds are estimates of metal contained in tonnages and do not include allowances for processing losses. Contained (cont.) gold ounces are reported as troy ounces, rounded to the nearest 10,000. Copper is reported as pounds.
6.Rounding of tonnes and contained metal content as required by reporting guidelines may result in apparent differences between tonnes, grade and contained metal content. Due to rounding, some cells may show a zero (“0”).
7.Totals may not sum due to rounding.
For mineral reserves, Newmont applies a time discount factor to the dollar value block model that is generated in the pit-limit analysis, to account for the fact that a pit will be mined over a period of years, and that the cost of waste stripping in the early years must bear the cost of the time value of money. Optimization work involved floating pit shells at a series of gold and copper prices. The pit shells with the highest NPV were selected for detailed engineering design work. A realistic schedule was developed in order to determine the optimal pit shell; schedule inputs include the minimum mining width, and vertical rate of advance, mining rate and mining sequence.
The mine plan is based on a 42 Mt/a mill throughput. The schedule was developed at an NSR cut-off of AU$17.06/t, incorporating the processing cost, metallurgical recovery, incremental ore mining costs, process sustaining capital and tailings dam related rehabilitation costs. The net revenue calculation assumes a gold price of US$1,200/oz or AU$1,600/oz, and a copper price of US$2.75/lb or AU$3.66/lb. The assumed exchange rate for mineral reserves was 0.75 US$:AU$. Mineral reserves are reported above an NSR cut-off of AU$17.06/t.
Pit designs are full crest and toe detailed designs with final ramps based on the selected optimum Whittle cones. Pit designs honor geotechnical guidelines with 15.2 m catch berms. Most of the ore will be directly fed to the process plant; however, some re-handle is required. Direct feeding to the crusher is constrained by where the ore is located in the open pit and the crusher availability. Some higher-grade ore is stockpiled and fed back to the crusher when required. Approximately 50% of feed is re-handle material from the stockpiles.
Block ore volumes are adjusted for waste proportions. Small dolerite volumes are added to the grade variables as dilution as they are narrower than the selective mining unit (SMU). Larger dolerite volumes are applied to the block as a waste portion and increased by a set amount which represents ore loss against the dolerite contact. Blocks containing >50% oxide material are classified as waste and have the grade set to zero.
Stockpile estimates were based on mine dispatch data; the grade comes from closely-spaced blasthole sampling and tonnage sourced from truck factors. The stockpile volumes were typically updated based on monthly surveys. The average grade of the stockpiles was adjusted based on the material balance to and from the stockpile.
Commodity prices used in mineral reserve estimation are based on long-term analyst and bank forecasts, supplemented with research by Newmont’s internal specialists. The estimated timeframe used for the price forecasts is the 14-year LOM.
| | | | | | | | |
Date: February, 2022 | | Page 1-10 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
1.12.2 Mineral Reserve Statement
Mineral reserves were classified using the definitions set out in SK1300 and are current as at December 31, 2021. The reference point for the mineral reserve estimate is at the point of delivery to the process facilities.
The proven and probable mineral reserve estimates for the Boddington Operations are summarized in Table 1-5 (gold) and Table 1-6 (copper).
| | | | | | | | |
Date: February, 2022 | | Page 1-11 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Table 1-5: Proven and Probable Mineral Reserve Statement (Gold)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Proven Mineral Reserves | Probable Mineral Reserves | Proven and Probable Mineral Reserves |
Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) |
Open pit | 237,400 | 0.70 | 5,360 | 239,100 | 0.66 | 5,090 | 476,500 | 0.68 | 10,450 |
Stockpile | 2,600 | 0.68 | 60 | 79,100 | 0.43 | 1,090 | 81,800 | 0.44 | 1,140 |
Boddington Total | 240,100 | 0.70 | 5,420 | 318,200 | 0.60 | 6,170 | 558,300 | 0.65 | 11,590 |
Table 1-6: Proven and Probable Mineral Reserve Statement (Copper)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Proven Mineral Reserves | Probable Mineral Reserves | Proven and Probable Mineral Reserves |
Tonnage (x 1,000 t) | Grade (Cu %) | Cont. Copper (M lbs) | Tonnage (x 1,000 t) | Grade (Cu %) | Cont. Copper (M lbs) | Tonnage (x 1,000 t) | Grade (Cu %) | Cont. Copper (M lbs) |
Open pit | 237,400 | 0.10 | 550 | 239,100 | 0.11 | 590 | 476,500 | 0.11 | 1,140 |
Stockpile | 2,600 | 0.09 | 10 | 79,100 | 0.09 | 150 | 81,800 | 0.09 | 160 |
Boddington Total | 240,100 | 0.10 | 550 | 318,200 | 0.11 | 740 | 558,300 | 0.11 | 1,300 |
| | | | | | | | |
Date: February, 2022 | | Page 1-12 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Notes to Accompany Mineral Reserve Tables:
1.Mineral reserves are current as at December 31, 2021. Mineral reserves are reported using the definitions in SK1300 on a 100% basis. The Qualified Person responsible for the estimate is Mr. Donald Doe, RM SME, Group Executive, Reserves, a Newmont employee.
2.The reference point for the mineral reserve estimates is the point of delivery to the process plant.
3.Mineral reserves that will be mined using open pit mining methods are constrained within a designed pit. Parameters used are included in Table 12-1.
4.Tonnages are metric tonnes rounded to the nearest 100,000. Gold grade is rounded to the nearest 0.01 gold grams per tonne. Copper grade is %. Gold ounces and copper pounds are estimates of metal contained in tonnages and do not include allowances for processing losses. Contained (cont.) gold ounces are reported as troy ounces, rounded to the nearest 10,000. Copper is reported as pounds. Rounding of tonnes and contained metal content as required by reporting guidelines may result in apparent differences between tonnes, grade and contained metal content. Due to rounding, some cells may show a zero (“0”).
5.Totals may not sum due to rounding.
| | | | | | | | |
Date: February, 2022 | | Page 1-13 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
1.12.3 Factors That May Affect the Mineral Reserve Estimate
Areas of uncertainty that may materially impact the mineral reserve estimates include: changes to long-term metal price and exchange rate assumptions; changes to metallurgical recovery assumptions; changes to the input assumptions used to derive the pit designs applicable to the open pit mining methods used to constrain the estimates; changes to the forecast dilution and mining recovery assumptions; changes to the cut-off values applied to the estimates; variations in geotechnical (including seismicity), hydrogeological and mining method assumptions; and changes to environmental, permitting and social license assumptions.
1.13 Mining Methods
The geotechnical model for the Boddington deposit was defined by geotechnical drilling and logging, laboratory test work, rock mass classification, structural analysis, and stability modeling.
The hydrological model was based on a three-dimensional flow model, historic pumping rates, and drill data. Overall pit slope angles varied between approximately 37–52º according to geology and location of pit infrastructure such as ramps and haul roads.
The pit dewatering system will continuously receive large volumes of groundwater and surface run-off over the LOM. The sum of active and passive dewatering has been relatively constant at approximately 140 L/sec; the long-term dewatering strategy assumes that this trend continues throughout the LOM. The water management strategy is to maximize the use of groundwater within the process plant and the loss of excess water by evaporation from the TSF. There is provision in place to capture excess surface water in water storage reservoirs.
The LOM plan envisages mining at an average rate of approximately 80 Mt/a for 14 years, peaking at 93 Mt/a in 2035, with a maximum rate of advance by pit stage of seven benches per annum and an average of five benches (60 m) per year. The mine plan assumes eight pit phases remain. The mine life will extend to 2034 with material mined from the open pit. Processing will cease in 2035 after treatment of stockpiled ore.
1.14 Recovery Methods
The process plant design was based on a combination of metallurgical testwork, previous study designs, and previous operating experience. The design is conventional to the gold industry and has no novel parameters.
The process consists of: primary crushing, closed circuit secondary and high-pressure grind roll tertiary crushing, ball milling; flotation to produce a copper–gold concentrate; and conventional leach/adsorption of the cleaner–scavenger tailings stream to produce doré.
Power supply to the operations is via the local grid system. Water supply is from a number of sources including local rivers, pit dewatering water, borefield water adjacent to the pits, rainfall run-off and recovered water from the process plant thickeners and TSF. Consumables used in the processing include grinding media, primary collector (thionocarbamate), secondary collector (xanthate), frother, lime, flocculant, cyanide, oxygen, caustic, sulfuric and hydrochloric acid, and peroxide.
| | | | | | | | |
Date: February, 2022 | | Page 1-14 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
1.15 Infrastructure
The majority of the key infrastructure to support the Boddington Operations mining activities envisaged in the LOM is in place. A second TSF will be required for the LOM plan. Within Newmont’s ground holdings, there is sufficient area to allow construction of any additional infrastructure that may be required in the future.
The existing infrastructure, staff availability, existing power, water, and communications facilities, and the methods whereby goods are transported to the mine are all in place and well-established, and can support the estimation of mineral resources and mineral reserves.
Personnel commute from surrounding settlements or live in a purpose-built accommodation village.
A number of WRSFs are in use, segregated as oxide or rock facilities. Potentially acid-forming waste is encapsulated within the WRSFs as required.
Boddington operates two run-of-mine (ROM) stockpiles and two medium-grade stockpiles. The stockpiles are reclaimed using a preferential high-grade feed strategy, with the lower medium-grade stockpiles being re-handled to the mill towards the end of the LOM.
The F1/F3 residue disposal area (RDA) is the current active TSF for the Boddington Operations.
The current F1/F3 dam has approved capacity to 600 Mt, which will provide tailings storage to 2025, assuming remaining capacity of 163 Mt, and an approximate 42 Mt/a process rate. The approved facility has 11 perimeter embankments, of which all are in place.
Newmont plans to expand the facility to 750 Mt, which, assuming the same approximate 42 Mt/a process rate, will provide tailings capacity to 2029. The expansion to 750 Mt is not currently permitted.
Additional storage that will be required for the LOM beyond 2029 is being evaluated by Newmont. This is currently envisaged as a new RDA with a 250 Mt capacity. Newmont has established a pathway and a timeline for the RDA approval and construction such that storage capacity will be available when needed.
Water management infrastructure for mine operations includes pit dewatering and mine surface water drainage infrastructure.
Power is sourced from the Bluewater Power Station, a coal-fired power station located 4.5 km northeast of the town of Collie, which is located approximately 80 km from the mine. Power is transmitted through the State power grid from the power station to the mine site.
1.16 Markets and Contracts
Newmont has established contracts and buyers for copper concentrate products, and has an internal marketing group that monitors markets for its concentrate. Together with public documents and analyst forecasts, there is a reasonable basis to assume that for the LOM plan, the copper concentrate will be saleable at the assumed commodity pricing.
The terms contained within the concentrate sales contracts are typical and consistent with standard industry practice for high-gold, low-copper concentrates. The contracts include industry benchmark terms for metal payables, treatment charges and refining charges for
| | | | | | | | |
Date: February, 2022 | | Page 1-15 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
concentrates produced. Depending on the specific contract, the terms for the sale of Boddington’s copper concentrate are either annually negotiated, benchmark-based treatment and refining charges, or a combination of annually-negotiated terms. Treatment charges assumed for estimation of mineral reserves are based on the forecasts published by third-party data providers such as Wood Mackenzie or CRU. The formula used for mineral reserves is sensitive to the underlying copper price and is consistent with long-term expectations for copper treatment and refining charges. Newmont’s doré is sold on the spot market, by marketing experts retained in-house by Newmont. The terms contained within the sales contracts are typical and consistent with standard industry practice and are similar to contracts for the supply of doré elsewhere in the world.
Newmont uses a combination of historical and current contract pricing, contract negotiations, knowledge of its key markets from a long operations production record, short-term versus long-term price forecasts prepared by Newmont’s internal marketing group, public documents, and analyst forecasts when considering long-term commodity price forecasts. Higher metal prices are used for the mineral resource estimates to ensure the mineral reserves are a sub-set of, and not constrained by, the mineral resources, in accordance with industry-accepted practice.
The largest in-place contracts other than for product sales cover items such as bulk commodities, operational and technical services, mining and process equipment, and administrative support services. Contracts are negotiated and renewed as needed. Contract terms are typical of similar contracts in Australia that Newmont is familiar with.
1.17 Environmental, Permitting and Social Considerations
1.17.1 Environmental Studies and Monitoring
Baseline and supporting environmental studies were completed to assess both pre-existing and ongoing site environmental conditions, as well as to support decision-making processes during operations start-up and restart. Characterization studies were completed for all environmental media including soil, water, waste, air, noise and closure.
Plans were developed and implemented to address aspects of operations such as waste and fugitive dust management, spill prevention and contingency planning, water management, and noise levels.
There are five species classified as Threatened Species/Matters of National Environmental Significance in the Project area, including three species of black cockatoo (Baudin’s, Carnaby’s and Forest Red-Tailed), and two species of marsupial, woylie and chuditch. All five species have site-specific management plans.
1.17.2 Closure and Reclamation Considerations
The most recent closure plan was submitted in 2019. The closure plan covers rehabilitation of the WRSFs, TSF, processing plant and other areas of disturbance.
In 2021, the annual 1% liability levy under the Mine Rehabilitation Fund that is charged to the site and remains in effect until all tenements were signed off as rehabilitated, amounted to approximately AU$1,403 M. Due to the bauxite State Agreements, there is one tenement for
| | | | | | | | |
Date: February, 2022 | | Page 1-16 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
which the Mine Rehabilitation Fund does not apply, and a bond, to the value of AU$3.63 M, was lodged.
Newmont also calculates the closure costs for the Boddington Operations as part of internal closure and financial planning. The closure estimate, as at 2021, assuming operations to 2035, is calculated as approximately AU$0.5 B.
1.17.3 Permitting
All major permits and approvals are either in place or Newmont expects to obtain them in the normal course of business. Additional permitting will be required to support the tailings disposal required in the LOM plan. Where permits have specific terms, renewal applications are made of the relevant regulatory authority as required, prior to the end of the permit term.
Newmont monitors the regulatory regime in place at each of its operations and ensures that all permits are updated in line with any regulatory changes.
1.17.4 Social Considerations, Plans, Negotiations and Agreements
Newmont defines the host communities for the Boddington Operations as those within a 50 km radius of the operation. These include the local government areas of Boddington, Williams, and Wandering, and the community of Dwellingup. Newmont has well-established relationships, engagement forums, and a suite of integrated social impact and opportunity-aligned strategic investment partnerships.
The operations area is subject to the South West Native Title Settlement. he Preservation of Aboriginal Heritage Agreement ensures that Newmont meets and exceeds the minimum obligations prescribed in the State’s Aboriginal Heritage Act 1972.
1.18 Capital Cost Estimates
Capital cost estimates are at a minimum at a pre-feasibility level of confidence, having an accuracy level of ±25% and a contingency range not exceeding 15%.
Capital costs are based on recent prices or operating data. Capital costs include funding for infrastructure, pit dewatering, development drilling, and permitting as well as miscellaneous expenditures required to maintain production. Mobile equipment re-build/replacement schedules and fixed asset replacement and refurbishment schedules are included. Sustaining capital costs reflect current price trends.
The overall capital cost estimate for the LOM is AU$1.8 B, as summarized in Table 1-7.
1.19 Operating Cost Estimates
Operating cost estimates are at a minimum at a pre-feasibility level of confidence, having an accuracy level of ±25% and a contingency range not exceeding 15%.
Operating costs are based on actual costs seen during operations and are projected through the LOM plan. Historical costs are used as the basis for operating cost forecasts for supplies and services unless there are new contract terms for these items. Labor and energy costs are based on budgeted rates applied to headcounts and energy consumption estimates.
| | | | | | | | |
Date: February, 2022 | | Page 1-17 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Operating costs for the LOM are estimated at AU$11.7 B, as summarized in Table 1-8. The estimated LOM mining cost is AU$4.31/t. Base processing costs are estimated at AU$11.11/t. In addition, G&A costs are estimated at AU$2.25/t.
Table 1-7: Capital Cost Estimate
| | | | | | | | | | | |
Area | Unit | Value | |
Mining | AU$ B | 0.7 | |
Process | AU$ B | 1.1 | |
Site G&A | AU$ B | 0 | * |
Total | AU$ B | 1.8 | |
Note: numbers have been rounded; totals may not sum due to rounding. * The zero in the table represents numeric data that do not display due to the rounding.
Table 1-8: Operating Cost Estimate
| | | | | | | | |
Area | Unit | Value |
Mining | AU$ B | 4.2 |
Process | AU$ B | 6.2 |
G&A | AU$ B | 1.3 |
Total | AU$ B | 11.7 |
Note: numbers have been rounded; totals may not sum due to rounding.
| | | | | | | | |
Date: February, 2022 | | Page 1-18 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
1.20 Economic Analysis
1.20.1 Economic Analysis
The financial model that supports the mineral reserve declaration is a standalone model that calculates annual cash flows based on scheduled ore production, assumed processing recoveries, metal sale prices and AU$/US$ exchange rate, projected operating and capital costs and estimated taxes.
The financial analysis is based on an after-tax discount rate of 5%. All costs and prices are in unescalated “real” dollars. The currency used to document the cash flow is US$.
All costs are based on the 2022 budget. Revenue is calculated from the recoverable metals and long-term metal price and exchange rate forecasts.
The Boddington Operations are subject to a federal tax rate of 30% on taxable income.
The economic analysis assumes constant prices with no inflationary adjustments.
The NPV5% is US$2.1 B. As the cashflows are based on existing operations where all costs are considered sunk to 1 January 2022, considerations of payback and internal rate of return are not relevant.
A summary of the financial results is provided in Table 1-9. In this table, EBITDA = earnings before interest, taxes, depreciation and amortization. The active mining operation ceases in 2034, and processing ceases in 2035; however, closure costs are estimated to 2055.
Table 1-9: Cashflow Summary Table
| | | | | | | | |
Item | Unit | Value |
Metal prices |
Gold | US$/oz | 1,200 |
Copper | US$/lb | 2.75 |
Mined Ore |
Tonnage | M tonnes | 558 |
Gold grade | g/t | 0.65 |
Copper grade | % | 0.11% |
Gold ounces | Moz | 11.6 |
Copper pounds | Blb | 1.3 |
Capital costs | US$B | 1.3 |
Costs applicable to sales | US$B | 9.7 |
Discount rate | % | 5 |
Exchange rate | Australian dollar:United States dollar (AUD:USD) | 0.75 |
Free cash flow | US$B | 2.7 |
Net present value | US$B | 2.1 |
Note: Numbers have been rounded; totals may not sum due to rounding. Table 1-9 contains “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, which are intended to be covered by the safe harbor created by such sections and other applicable laws. Please refer to the note regarding forward-looking information at the front of the Report. The cash flow is only intended to demonstrate the financial viability of the Project. Investors are cautioned that the above is based upon certain assumptions which may differ from Newmont’s long-term outlook or actual financial results, including, but not limited to commodity prices, escalation assumptions and other technical inputs. For example, Table 1-9 uses the price assumptions stated in the table, including a gold commodity price
| | | | | | | | |
Date: February, 2022 | | Page 1-19 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
assumption of US$1,200/oz, which varies significantly from current gold prices and the assumptions that Newmont uses for its long-term guidance. Please be reminded that significant variation of metal prices, costs and other key assumptions may require modifications to mine plans, models, and prospects.
1.20.2 Sensitivity Analysis
The sensitivity of the Project to changes in metal prices, exchange rate, sustaining capital costs and operating cost assumptions was tested using a range of 25% above and below the base case values (Figure 1-1).
The Project is most sensitive to metal price changes, less sensitive to changes in operating costs, and least sensitive to changes in capital costs.
The sensitivity to grade mirrors the sensitivity to the gold price and is not shown.
Figure 1-1: NPV Sensitivity
Note: Figure prepared by Newmont, 2021. FCF = free cashflow; op cost = operating cost; cap cost = capital cost; NPV = net present value.
1.21 Risks and Opportunities
Factors that may affect the mineral resource and mineral reserve estimates are summarized in Chapter 1.11.3 and Chapter 1.12.3.
1.21.1 Risks
The risks associated with the Boddington site are generally those expected with a large surface mining operation and include the accuracy of the resource model, unexpected geological features that cause geotechnical issues, dewatering difficulties and/or operational impacts.
| | | | | | | | |
Date: February, 2022 | | Page 1-20 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Other risks noted include:
•Commodity price increases for key consumables such diesel, electricity, tires and chemicals would negatively impact the stated mineral reserves and mineral resources;
•Labor cost increases or productivity decreases could also impact the stated mineral reserves and mineral resources, or impact the economic analysis that supports the mineral reserves;
•While the autonomous haulage system is currently operational any unforeseen issues with this innovative system could increase costs and/or lower expected productivities;
•With bauxite mining having precedence over other minerals there is a risk that any unexpected requirement to advance bauxite mining (or delay gold mining) could increase costs and/or delay the expected production profile;
•Geotechnical and hydrological assumptions used in mine planning are based on historical performance, and to date historical performance has been a reasonable predictor of current conditions. Any changes to the geotechnical and hydrological assumptions could affect mine planning, affect capital cost estimates if any major rehabilitation is required due to a geotechnical or hydrological event, affect operating costs due to mitigation measures that may need to be imposed, and impact the economic analysis that supports the mineral reserve estimates;
•The mine plan assumes that the existing TSF can be expanded from 600 Mt to 750 Mt. While there is sufficient time for the permitting process prior to the expansion being required in 2025, if there is a delay in the permitting process or the facility cannot be expanded, this could impact the mine plan, the mineral reserve estimates and the economic analysis that supports the mineral reserve estimates;
•The mine plan assumes that a second RDA can be constructed and permitted. Newmont has established a pathway and a timeline to develop additional tailings capacity such that storage capacity will be available when needed. However, if there are changes to the assumed pathway, to the ability to construct and permit such a facility, or to the timeline assumptions, this could impact the mine plan, the mineral reserve estimates and the economic analysis that supports the mineral reserve estimates;
•The mineral reserve estimates are very sensitive to metal prices. Lower metal prices than forecast in the LOM plan may require revisions to the mine plan, with impacts to the mineral reserve estimates and the economic analysis that supports the mineral reserve estimates;
•There are five species classified as Threatened Species/Matters of National Environmental Significance in the Project area. Although there are site-specific management plans in place, if there is a major impact seen on the populations from mining activities, the environmental permits for the operations could be revised or even revoked. The social license to operate could also be impacted;
•Climate changes could impact operating costs and ability to operate;
•There is a risk to the Boddington Operations overall if the Worsley JV were to fail to renew the mining leases, as Newmont’s interest relies on the existence of valid mining tenure.
| | | | | | | | |
Date: February, 2022 | | Page 1-21 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
1.21.2 Opportunities
Opportunities for the Boddington mine include moving the stated mineral resources into mineral reserves through additional drilling and study work. The mineral reserves and mineral resources are based on conservative price estimates for gold and copper so upside exists, either in terms of the potential to estimate additional mineral reserves and mineral resources or improved economics should the prices used for gold and copper be increased.
Opportunities include:
•Conversion of some or all of the measured and indicated mineral resources currently reported exclusive of mineral reserves to mineral reserves, with appropriate supporting studies;
•Upgrade of some or all of the inferred mineral resources to higher-confidence categories, such that such better-confidence material could be used in mineral reserve estimation;
•Higher metal prices than forecast could present upside sales opportunities and potentially an increase in predicted Project economics;
•Potential to link the north and south pits through the saddle area to form a single large open pit through mining and economic studies.
1.22 Conclusions
Under the assumptions presented in this Report, the Boddington Operations have a positive cash flow, and mineral reserve estimates can be supported.
1.23 Recommendations
As Boddington is an operating mine, the QP has no material recommendations to make.
| | | | | | | | |
Date: February, 2022 | | Page 1-22 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
2.0 INTRODUCTION
2.1 Registrant
This technical report summary (the Report) was prepared for Newmont Corporation (Newmont) on the Boddington Operations (Boddington Operations or the Project) located in southern Western Australia (Figure 2-1).
2.2 Terms of Reference
2.2.1 Report Purpose
The Report was prepared to be attached as an exhibit to support mineral property disclosure, including mineral resource and mineral reserve estimates, for the Boddington Operations in Newmont’s Form 10-K for the year ending December 31, 2021.
Mineral resources and mineral reserves are reported for the North and South pits (also referred to as Wandoo North and Wandoo South). Mineral reserves are also estimated for material in stockpiles.
2.2.2 Terms of Reference
The Boddington Operations currently consist of two open pit mines, the North and the South pits.
Gold operations were conducted in two phases. The initial oxide operations, a combination of open pit and underground mining, ran from 1987–2001. The current operations commenced in 2009 from open pit sources. Figure 2-2 shows the location of the current and mined-out open pits, and development prospects.
Unless otherwise indicated, all financial values are reported in Australian dollars (AU$).
Unless otherwise indicated, the metric system is used in this Report.
Mineral resources and mineral reserves are reported using the definitions in Regulation S–K 1300 (SK1300), under Item 1300.
The Report uses US English.
The Report contains forward-looking information; refer to the note regarding forward-looking information at the front of the Report.
2.3 Qualified Persons
The following Newmont employee serves as the Qualified Person (QP) for the Report:
•Mr. Donald Doe, RM SME., Group Executive, Reserves, Newmont.
Mr. Doe is responsible for all Report Chapters.
| | | | | | | | |
Date: February, 2022 | | Page 2-1 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Figure 2-1: Project Location Plan
| | | | | | | | |
Date: February, 2022 | | Page 2-2 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Figure 2-2: Mining Operations Layout Plan
| | | | | | | | |
Date: February, 2022 | | Page 2-3 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
2.4 Site Visits and Scope of Personal Inspection
Mr. Doe visited the Boddington Operations on many occasions, most recently from August 25–27 2019.
During site visits to the Project, Mr. Doe inspects the operating open pits, and views the process plant and associated general site infrastructure, including the current tailings storage facility (TSF) operations. While on site, he discusses aspects of the operation with site-based staff and assesses the knowledge and abilities of the site staff to carry out their duties as required. These site discussions include the overall approach to the mine plan, anticipated mining conditions, selection of the production target and potential options for improvement. Other areas of discussion include plant operation and recovery forecasts, capital and operating forecasts and results.
Mr. Doe receives and reviews monthly reconciliation reports from the mine. These reports include the industry standard reconciliation factors for tonnage, grade and metal; F1 (mineral reserve model compared to ore control model), F2 (mine delivered compared to mill received) and F3 (F1 x F2) along with other measures such as compliance of actual production to mine plan and polygon mining accuracy. The reconciliation factors are recorded monthly and reported in a quarterly control document. Through the review of these reconciliation factors, the QP is able to ascertain the quality and accuracy of the data and its suitability for use in the assumptions underlying the mineral resource and mineral reserves estimates.
Mr. Doe also reviews Newmont’s processes and internal controls at the mine site with operational staff on the work flow for determining mineral resource and mineral reserves estimates, mineral process performance, mining costs, and waste management.
2.5 Report Date
Information in the Report is current as at December 31, 2021.
2.6 Information Sources and References
The reports and documents listed in Chapter 24 and Chapter 25 of this Report were used to support Report preparation.
2.7 Previous Technical Report Summaries
Newmont has not previously filed a technical report summary on the Project.
| | | | | | | | |
Date: February, 2022 | | Page 2-4 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
3.0 PROPERTY DESCRIPTION
3.1 Introduction
The Boddington Operations are located about 130 km southeast of the city of Perth and 17 km northwest of the township of Boddington. The Project centroid is situated at approximately 32°44'15.99"S and 116°21'34.76"E. The open pit operations are centered on:
•North Pit: 2°44'34"S and 116°20'24"E
•South Pit: 32°45'18"S and 116°21'30"E.
3.2 Property and Title in Western Australia
3.2.1 Mineral Title
In Australia, with few exceptions, all onshore mineral rights are reserved by the government of the relevant State or Territory. Exploration for, and mining of, minerals is regulated by the general mining legislation and controlled by the mining ministry of each respective State or Territory.
The most common forms of tenure are exploration and prospecting licenses, mining leases, and general purpose leases. In most Australian states, if the holder of an exploration license establishes indications of an economic mineral deposit and complies with the conditions of the grant, the holder of the exploration license has a priority right against all others to apply for a mining lease which gives the holder exclusive mining rights with respect to minerals on the property. It is possible for an individual or entity person to own the surface of the property, and for another to own the mineral rights.
Government royalties are payable as specified in the relevant legislation in each State or Territory. A general purpose lease may also be granted for one or more of a number of permitted purposes. These purposes include erecting, placing and operating machinery and plant in connection with mining operations, depositing or treating minerals or tailings and using the land for any other specified purpose directly connected with mining operations.
Where native title has not been extinguished, native title legislation may apply to the grant of tenure and some subsequent administrative processes. Federal and State Aboriginal heritage legislation also operates to protect special sites and areas from disturbance.
The Australian Federal Government has certain oversight and approvals relating to environmental matters of national significance. The Federal Government also has the power to restrict mineral exports for the good of the country, and can exert control over most mineral production.
In Western Australia (WA), ownership of all minerals is vested in the State Government, administered the mineral industries within its own borders, which includes registering land titles; issuing exploration and development permits; overseeing mining operations (which included administration of inspections); assuring compliance with health, safety, and environmental regulations; and levying royalties and taxes.
| | | | | | | | |
Date: February, 2022 | | Page 3-1 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Exploration and mining companies and individuals may access rights to minerals in WA, subject to payment of application fees, rents and royalties, by obtaining exclusive mining title, in the form of mining “tenements”. The most common WA tenure types are summarized in Table 3-1.
Table 3-1: Tenure Types in Western Australia
| | | | | |
License Type | Comment |
Mining Prospecting License/Special Prospecting License for Gold | Four-year term. Can be extended for a single four-year term. Maximum area of 200 ha for prospecting license and 10 ha for special license. |
Exploration License | Five-year term. At the end of both the third and fourth year, must surrender 50% of license. For a license applied for and granted after 10 February 2006, the surrender requirement is 40% at the end of the sixth year. Minimum 1 block* size, maximum 70 blocks, except in areas not designated as mineralized areas, where the maximum size is 200 blocks. |
Mining Lease | 21-year term, can be renewed. The maximum area for a mining lease (M) applied for before 10 February 2006 is 1,000 ha. After that date, the size applied for must relate to an identified orebody as well as an area for infrastructure requirements. |
Retention License | A “holding" title for a Mineral Resource that has been identified but is not able to be further explored or mined. Cannot exceed five years and is renewable for additional periods not exceeding five years. There is no maximum area. |
General Purpose Lease | For infrastructure related to mining operations, such as camp facilities, operating machinery or depositing or treating tailings. 21-year term, and can be renewed. The maximum area is 10 ha, unless Ministerial Consent is given for a larger area. General purpose leases must be marked out and are limited to a depth of 15 m or such other depth that may be specified |
Miscellaneous License | For purposes such as a road, pipeline, or water. 21-year term, and can be renewed. There is no maximum area. |
State Agreement | State Agreements (SA) are contracts between the State and major project developers that establish a framework of rights and obligations to facilitate the development of resources and/or downstream processing projects in Western Australia. These agreements are ratified by an Act of the WA Parliament known as a State Agreement Act. |
Note: * A block is a graticular unit. A graticular block is an area of land five minutes of latitude long, by five minutes of longitude wide. There are 25 sub-blocks to a block. The average block is about 75 km2 or 7,500 ha.
3.2.2 Surface Rights
Surface rights are generally divisible into two categories: Crown land and private land.
Where land is vested in the Crown, typically mining companies deal with government bodies to determine the social impact of the application, and any potential conflicts in land usage, such as forestry or national parks. Crown land can be subject to pastoral or other leasehold arrangements, in which case, mining companies need also to negotiate with the relevant leaseholder.
In the case of private land, normal free-market negotiations and agreements apply.
3.2.3 Native Title and Heritage Protection
The common law of Australia recognizes a form of native title, under the Native Title Act 1993 (Commonwealth of Australia) (Native Title Act).
| | | | | | | | |
Date: February, 2022 | | Page 3-2 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
The Aboriginal Heritage Act 1972 (WA) (WA Heritage Act) applies to mining tenements and makes it an offence to, among other things, alter or damage an Aboriginal site. An Aboriginal site is defined to include any sacred, ritual or ceremonial site which is of importance and special significance to persons of Aboriginal descent. There is no requirement or need for a site to be registered in any public manner or be in any way acknowledged as an Aboriginal site for it to qualify as an Aboriginal site for the purposes of the WA Heritage Act.
The Aboriginal and Torres Strait Islander Heritage Act 1984 (Commonwealth of Australia) also applies to mining tenements and is aimed at the preservation and protection from desecration of significant Aboriginal areas and significant Aboriginal objects. An area or object is found to be desecrated if it is used or treated in a manner inconsistent with Aboriginal tradition.
3.2.4 Government Mining Taxes, Levies or Royalties
Mineral royalties are collected under either the Mining Act 1978 (WA) or State Agreement Acts which are negotiated for individual projects. In some cases, the State Agreement Act contains specific royalty clauses, while in other cases it simply refers to the Mining Act 1978 (WA) royalty sections.
In Western Australia there are three systems of mineral royalty collection used:
•Specific rate: flat rate per tonne;
•Ad valorem: percentage of value;
•Profit-based: percentage of profit.
When any minerals are produced or obtained from a mining tenement, a quarterly production report must be lodged and a gold, silver and copper royalty is payable to the WA government.
The copper royalty is 5% of the realized copper value and is payable in Australian dollars. The realized copper value is the copper payment made by the smelter, less all contracted costs associated with shipment, treatment and refining of the concentrate and metals arising thereof. The silver royalty is 2.5% of the realized silver value and is payable in US currency. The realized silver value is the silver payment made by the smelter less the cost of silver refining. No gold royalty is payable in respect of the first 2,500 oz of gold produced by a mine in any financial year. For production in excess of 2,500 oz/a, the gold royalty is 2.5% of the gold value.
3.3 Ownership
3.3.1 Ownership History
The majority of the Boddington Operations area is located within the original boundaries of a single large tenement (M258SA) granted under a State Agreement known as the Worsley State Agreement. M258SA is held by the Worsley Joint Venture (Worsley JV) and permits the mining of bauxite only. The current participants of the Worsley JV are:
•South32 Aluminium (RAA) Pty Ltd: 56%;
•South32 Worsley Alumina Pty Ltd: 30%;
•Japan Alumina Associates (Australia) Pty Ltd: 10%;
| | | | | | | | |
Date: February, 2022 | | Page 3-3 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
•Sojitz Alumina Pty Ltd: 4%.
In the early 1980s, the Worsley JV discovered gold mineralization at Boddington. The Worsley State Agreement was amended to enable the granting of all minerals leases under the Mining Act of Western Australia 1978 within the boundaries of M258SA. On grant of such mineral leases these areas would be temporarily excised from M258SA. Under the Worsley State Agreement when the Mining Act Mining Leases are relinquished, the area reverts to M258SA.
The Worsley JV established a new joint venture to exploit the gold mineralization, the Boddington Gold Mine Joint Venture (BGMJV). The BGMJV Agreement was entered into on 31 March 1987 and initially consisted of the same participants as the Worsley JV. The relationship between the bauxite/alumina operations and the gold operations was regulated under a cross-operation agreement which, in a restated form, continues as of the Report date.
The paramount principle regulating the relationship between the Worsley JV and the BGMJV was that bauxite and bauxite operations were to have priority over all other minerals within an area (the Common Area) that was defined within the boundaries of M258SA. This interpretation remains current as of the Report date. Consequently, where bauxite is found in an area of the mining leases where Newmont is active, Newmont is required to mine and stockpile bauxite on behalf of the Worsley JV.
Ownership of the BGMJV changed over time so that the participants in the Worsley JV were no longer the same as the BGMJV participants. In order to accommodate the transfer of ownership to incoming BGMJV participants whilst maintaining bauxite rights, a series of transactions were entered into that resulted in the present structure whereby the BGMJV participants sublease the mining leases on which the gold mineralization is located.
Newmont acquired its interest in the BGMJV through the transactions summarized in Table 3-2.
3.3.2 Current Ownership
Since 2009, Newmont has had 100% ownership of the BGMJV. The current parties to the BGMJV are Newmont Boddington Pty Ltd (66⅔%) and Saddleback Investments Pty Ltd (Saddleback; (33⅓%). Both companies are indirectly-wholly owned Newmont subsidiaries.
3.4 Property Agreements
3.4.1 Background
The region in which the Project is located is a well-known bauxite-alumina mining and production area now held predominantly by either the Worsley JV or the Alcoa Australia Group pursuant to their respective State Agreements. The major part of the Mining Act tenure (including M70/21–26, M70/564 and M70/799) lies within the original boundaries of a tenement granted under the Worsley State Agreement (M258SA). The remainder of the tenure (including M264SAand M70/1031) lies within the original boundaries of another State Agreement Area known as the Alcoa State Agreement (M1SA).
Newmont subleases from the Worsley JV the key mining leases upon which the Boddington operations are located, namely M70/21–26, M70/564 and M70/799. Newmont is entitled to all gold and other non-bauxite mining rights conferred by the lease. The Worsley JV retains the rights to bauxite and priority rights of access in order to mine and recover such bauxite. Where
| | | | | | | | |
Date: February, 2022 | | Page 3-4 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
any new leases within the original area of M258SA are granted to the Worsley JV, the non-bauxite rights under such leases will be held by the Worsley JV for and on behalf of the BGMJV.
Table 3-2: Transactions Through Which Newmont Acquired Its Interest in the BGMJV
| | | | | | | | | | | |
Year | Interest | Seller | Purchaser |
1995 | 4 and 4/9% | Japan Alumina Associates (Australia) Pty Ltd (then called Kobe Alumina Associates (Australia) Pty Limited) | Newmont Boddington Pty Ltd (then called PosGold (Boddington) Pty Ltd and ultimately held by Normandy Mining Limited) |
1995 | 40% | Reynolds Australia Alumina Ltd | Newmont Boddington Pty Ltd (then called PosGold (Boddington) Pty Ltd and ultimately held by Normandy Mining Limited) |
2002 | | Newmont Mining Corporation acquires 100% of Normandy Mining Limited, which was the ultimate owner of PosGold (Boddington) Pty Ltd. | |
2006 | 22 and 2/9% | Newcrest Operations Limited | Newmont Boddington Pty Ltd |
2009 | 33 and 3/9% | AngloGold Ashanti Australia Limited | Saddleback Investments Pty Ltd |
3.4.2 Management Agreements
The relationship between the Worsley JV bauxite operations and the BGMJV gold operations is regulated through a cross-operation agreement. This agreement confers priority on the bauxite operations such that the operations of the Worsley JV will take priority over the operations of the BGMJV and the BGMJV are required to take reasonable measures to conserve bauxite including by mining and stockpiling bauxite on behalf of the Worsley JV.
The cross-operation agreement also requires the managers of the respective JVs to keep each other regularly informed as to current and proposed activities in order to alleviate or minimize any potential impact of one operation upon another.
3.5 Mineral Title
Newmont has an interest in a total of 89 tenements in the Boddington area The total granted area is approximately 21,249 ha and the under-application area is approximately 60,767 ha.
The actual mining area is covered by the following 13 WA Mining Act leases: M70/21–26, M70/564, M70/799, M70/1031, G70/215 and G70/218–219, and M264SA. Mining leases M70/21–26 and M70/799 are the key tenements under which gold mining activity is concentrated.
Through direct lease holding and sub-lease arrangements with the Worsley JV, Newmont holds the rights to minerals other than bauxite in proportion to the Newmont ownership percentages.
A total of 26 of the mining tenements are at an application stage. Under the Mining Act of Western Australia 1978, Mining Leases are granted for 21 years and are renewable. Five mining leases (M70/21–25) were renewed in March 2007 for a 21-year term.
Newmont has an automatic right to be granted new subleases when the tenements are renewed. The Worsley JV may renew the mining leases.
| | | | | | | | |
Date: February, 2022 | | Page 3-5 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Mineral tenure is summarized in Table 3-3, and a tenure location plan is provided as Figure 3-1.
Table 3-3: Mineral Tenure Summary Table
| | | | | | | | | | | | | | | | | | | | | | | |
Lease | Holder | Lease Type | Lease Status | Current Area | Application Date (dd/mm/year) | Grant Date (dd/mm/year) | Expiry Date (dd/mm/year) |
E70/2149 1 | A | Ex | Application | 28 blocks | 7/12/1998 | — | — |
E70/2336 1 | A | Ex | Application | 56 blocks | 25/05/2000 | — | — |
E70/2550 1 | A | Ex | Application | 7 blocks | 11/10/2002 | — | — |
E70/2562 1 | B | Ex | Application | 8 blocks | 2/12/2002 | — | — |
E70/3750 | C | Ex | Application | 40 blocks | 30/11/2009 | — | — |
E70/3982 | C | Ex | Application | 6 blocks | 1/10/2010 | — | — |
E70/4018 | C | Ex | Application | 3 blocks | 9/12/2010 | — | — |
E70/4019 | C | Ex | Application | 6 blocks | 9/12/2010 | — | — |
E70/4235 | C | Ex | Application | 2 blocks | 30/09/2011 | — | — |
E70/4301 | C | Ex | Application | 8 blocks | 22/02/2012 | — | — |
E70/4302 | C | Ex | Application | 6 blocks | 22/02/2012 | — | — |
M70/18 2 | D | M | Application | 884 ha | 8/04/1983 | — | — |
M70/19 2 | D | M | Application | 980 ha | 8/04/1983 | — | — |
M70/27 2 | D | M | Application | 747 ha | 14/04/1983 | — | — |
M70/28 2 | D | M | Application | 720 ha | 14/04/1983 | — | — |
M70/29 2 | D | M | Application | 690 ha | 14/04/1983 | — | — |
M70/30 2 | D | M | Application | 690 ha | 14/04/1983 | — | — |
M70/31 2 | D | M | Application | 907 ha | 14/04/1983 | — | — |
M70/32 2 | D | M | Application | 972 ha | 14/04/1983 | — | — |
M70/33 2 | D | M | Application | 856 ha | 14/04/1983 | — | — |
M70/34 2 | D | M | Application | 873 ha | 14/04/1983 | — | — |
M70/35 2 | D | M | Application | 967 ha | 14/04/1983 | — | — |
M70/36 2 | D | M | Application | 639 ha | 14/04/1983 | — | — |
M70/545 2 | E | M | Application | 1000 ha | 13/07/1989 | — | — |
M70/975 1 | F | M | Application | 990 ha | 14/01/1997 | — | — |
P70/1598 | C | P | Application | 27.56 ha | 24/06/2010 | — | — |
E70/710 3 | E | Ex | Granted | 9.44 km2 | 27/04/1988 | 16/01/1989 | 15/01/1997 |
G70/215 | C | G | Granted | 28.61 ha | 13/05/2005 | 16/06/2009 | 15/06/2030 |
G70/218 | C | G | Granted | 51.69 ha | 9/02/2006 | 16/08/2006 | 15/08/2027 |
G70/219 | C | G | Granted | 9.545 ha | 9/02/2006 | 13/12/2006 | 12/12/2027 |
L70/152 | C | L | Granted | 171.68 ha | 6/08/2012 | 14/03/2013 | 13/03/2034 |
L70/165 | C | L | Granted | 2.128 ha | 15/05/2014 | 22/09/2014 | 21/09/2035 |
L70/28 | C | L | Granted | 1.2 ha | 16/08/1993 | 4/11/1993 | 3/11/2023 |
L70/95 | C | L | Granted | 31 ha | 9/02/2006 | 5/05/2006 | 4/05/2027 |
L70/96 | C | L | Granted | 6 ha | 13/07/2006 | 10/11/2006 | 9/11/2027 |
L70/222 | C | L | Application | 33.25 ha | 10/09/2020 | | |
M264SA(1) | C | M | Granted | 497.35 ha | 28/12/1987 | 1/08/1988 | 31/07/2030 |
M264SA(2) | C | M | Granted | 408.9 ha | 28/12/1987 | 1/08/1988 | 31/07/2030 |
M70/1031 | C | M | Granted | 398.9 ha | 8/10/1998 | 11/10/1999 | 10/10/2020 |
M70/110 2 | F | M | Granted | 5.2955 ha | 25/11/1983 | 3/02/1989 | 2/02/2031 |
M70/111 2 | F | M | Granted | 121.3 ha | 25/11/1983 | 3/02/1989 | 2/02/2031 |
M70/112 2 | F | M | Granted | 29.37 ha | 25/11/1983 | 3/02/1989 | 2/02/2031 |
| | | | | | | | |
Date: February, 2022 | | Page 3-6 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
| | | | | | | | | | | | | | | | | | | | | | | |
Lease | Holder | Lease Type | Lease Status | Current Area | Application Date (dd/mm/year) | Grant Date (dd/mm/year) | Expiry Date (dd/mm/year) |
M70/113 2 | F | M | Granted | 64.485 ha | 25/11/1983 | 3/02/1989 | 2/02/2031 |
M70/114 2 | F | M | Granted | 817.8 ha | 25/11/1983 | 3/02/1989 | 2/02/2031 |
M70/115 2 | F | M | Granted | 702.2 ha | 25/11/1983 | 3/02/1989 | 2/02/2031 |
M70/116 2 | F | M | Granted | 749.3 ha | 25/11/1983 | 3/02/1989 | 2/02/2031 |
M70/1220 | C | M | Granted | 43.335 ha | 4/03/2005 | 14/11/2012 | 13/11/2033 |
M70/1221 | C | M | Granted | 929.3 ha | 4/03/2005 | 14/11/2012 | 13/11/2033 |
M70/1236 | C | M | Granted | 946 ha | 17/06/2005 | 25/11/2013 | 24/11/2034 |
M70/1237 | C | M | Granted | 987 ha | 17/06/2005 | 25/11/2013 | 24/11/2034 |
M70/1238 | C | M | Granted | 708 ha | 17/06/2005 | 25/11/2013 | 24/11/2034 |
M70/1239 | C | M | Granted | 960 ha | 17/06/2005 | 25/11/2013 | 24/11/2034 |
M70/21 3 | F | M | Granted | 978.05 ha | 14/04/1983 | 9/04/1986 | 8/04/2028 |
M70/22 3 | F | M | Granted | 984.6 ha | 14/04/1983 | 9/04/1986 | 8/04/2028 |
M70/23 3 | F | M | Granted | 966.9 ha | 14/04/1983 | 9/04/1986 | 8/04/2028 |
M70/24 3 | F | M | Granted | 986.15 ha | 14/04/1983 | 9/04/1986 | 8/04/2028 |
M70/25 3 | F | M | Granted | 968.38 ha | 14/04/1983 | 9/04/1986 | 8/04/2028 |
M70/26 3 | F | M | Granted | 527.25 ha | 14/04/1983 | 28/11/2014 | 27/11/2035 |
M70/462 | C | M | Granted | 476.25 ha | 1/11/1988 | 12/10/1989 | 11/10/2031 |
M70/463 | C | M | Granted | 359.65 ha | 1/11/1988 | 12/10/1989 | 11/10/2031 |
M70/464 | C | M | Granted | 725.6 ha | 1/11/1988 | 12/10/1989 | 11/10/2031 |
M70/465 | C | M | Granted | 359.55 ha | 1/11/1988 | 12/10/1989 | 11/10/2031 |
M70/466 | C | M | Granted | 109.5 ha | 1/11/1988 | 12/10/1989 | 11/10/2031 |
M70/554 2 | F | M | Granted | 38.61 ha | 13/07/1989 | 6/04/2004 | 5/04/2025 |
M70/564 3 | F | M | Granted | 363.8 ha | 29/08/1989 | 27/04/1990 | 26/04/2032 |
M70/588 | C | M | Granted | 360.15 ha | 31/10/1989 | 7/06/1990 | 6/06/2032 |
M70/589 | C | M | Granted | 120.05 ha | 31/10/1989 | 7/06/1990 | 6/06/2032 |
M70/590 | C | M | Granted | 402.55 ha | 31/10/1989 | 7/06/1990 | 6/06/2032 |
M70/591 | C | M | Granted | 359.9 ha | 31/10/1989 | 7/06/1990 | 6/06/2032 |
M70/731 | C | M | Granted | 300 ha | 3/12/1991 | 26/01/1993 | 25/01/2035 |
M70/799 3 | F | M | Granted | 925.4 ha | 21/01/1993 | 21/09/1993 | 20/09/2035 |
M70/944 | C | M | Granted | 1.5305 ha | 21/05/1996 | 5/12/1996 | 4/12/2038 |
M70/945 | C | M | Granted | 11.76 ha | 21/05/1996 | 5/12/1996 | 4/12/2038 |
M70/946 | C | M | Granted | 0.3385 ha | 21/05/1996 | 5/12/1996 | 4/12/2038 |
M70/947 | C | M | Granted | 15.63 ha | 21/05/1996 | 5/12/1996 | 4/12/2038 |
M70/948 | C | M | Granted | 2.496 ha | 21/05/1996 | 5/12/1996 | 4/12/2038 |
M70/949 | C | M | Granted | 34.925 ha | 21/05/1996 | 5/12/1996 | 4/12/2038 |
M70/950 | C | M | Granted | 16.465 ha | 21/05/1996 | 5/12/1996 | 4/12/2038 |
M70/951 | C | M | Granted | 3.88 ha | 21/05/1996 | 5/12/1996 | 4/12/2038 |
M70/952 | C | M | Granted | 12.13 ha | 21/05/1996 | 5/12/1996 | 4/12/2038 |
M70/953 | C | M | Granted | 2.6 ha | 21/05/1996 | 5/12/1996 | 4/12/2038 |
M70/954 | C | M | Granted | 12.865 ha | 21/05/1996 | 5/12/1996 | 4/12/2038 |
M70/955 | C | M | Granted | 1.349 ha | 21/05/1996 | 5/12/1996 | 4/12/2038 |
M70/976 1 | F | M | Granted | 861 ha | 14/01/1997 | 30/08/2013 | 29/08/2034 |
M70/981 | C | M | Granted | 52.19 ha | 25/03/1997 | 3/09/1997 | 2/09/2039 |
ML70/662 | C | ML | Granted | 90 ha | 18/12/1981 | 1/01/2002 | 31/12/2022 |
| | | | | | | | |
Date: February, 2022 | | Page 3-7 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
| | | | | | | | | | | | | | | | | | | | | | | |
Lease | Holder | Lease Type | Lease Status | Current Area | Application Date (dd/mm/year) | Grant Date (dd/mm/year) | Expiry Date (dd/mm/year) |
ML70/663 | C | ML | Granted | 90 ha | 18/11/1981 | 1/01/2002 | 31/12/2022 |
ML70/751 | C | ML | Granted | 120 ha | 26/11/1981 | 1/01/2002 | 31/12/2022 |
ML70/752 | C | ML | Granted | 120 ha | 26/11/1981 | 1/01/2002 | 31/12/2022 |
ML70/753 | C | ML | Granted | 50 ha | 26/11/1981 | 1/01/2002 | 31/12/2022 |
Notes:
A = Newcrest Operations Ltd (22.22%), Newmont Boddington Pty Ltd (44.44%), AngloGold Ashanti Australia Ltd (33.33%). B = Hedges Gold Pty Ltd (100%). C = Newmont Boddington Pty Ltd (66.67%), Saddleback Investments Pty Ltd (33.33%). D = BHP Billiton Minerals Pty Ltd (20%), South32 Aluminium (RAA) Pty Ltd (40%), Japan Alumina Associates (Australia) Pty Ltd (10%), The Shell Company of Australia Ltd (30%). E = South32 Aluminium (RAA) Pty Ltd (50%), Japan Alumina Associates (Australia) Pty Ltd (10%), Sojitz Alumina Pty Ltd (2.5%), The Shell Company of Australia Ltd (37.5%). F = South32 Aluminium (RAA) Pty Ltd (56%), South32 Worsley Alumina Pty Ltd (30%), Japan Alumina Associates (Australia) Pty Ltd (10%), Sojitz Alumina Pty Ltd (4%).
Ex = Exploration, G = General Purpose Lease, L = Miscellaneous License, M = Mining Lease, ML = Mineral Lease, P = Prospecting Permit.
1.Newmont 100% beneficial owner - upon grant can be transferred.
2.Newmont holds right to sub-lease.
3.Newmont holds a sub-lease.
| | | | | | | | |
Date: February, 2022 | | Page 3-8 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Figure 3-1: Mineral Tenure Location Plan
Note: Figure prepared by Newmont, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 3-9 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
At the Report date, all required payments had been made and all required statutory reporting had been filed with the West Australian Department of Mines, Industry Regulation and Safety.
3.6 Surface Rights
Newmont holds sufficient surface rights to execute the life-of-mine (LOM) plan. A map showing the surface rights is included as Figure 3-2.
The Boddington Operations have freehold ownership of all the eastern and central areas of operations. Within this freehold land are all the existing residue disposal areas, the plant site, almost all of the area of the main open pit from the former oxide operation, and all but one of the smaller satellite open pits from the 1987–2001 operation.
The western portion of the operational area is outside the freehold land is Crown land covered by native forest. Mining operations can be conducted in this area but with certain restrictions imposed by the State Government through the 1978 Mining Act that are applicable to forested Crown lands.
Newmont holds freehold land to the north and to the east of the current mining areas.
To the south and east of the Project is freehold farmland. The largest farm immediately south of the mine, Hotham Farm, was acquired in December 2011.
3.7 Native Title
The Boddington Operations area was previously subject to a land claim registered under the Native Title Act and referred to as the Gnaala Karla Booja Claim. This claim has now been settled (The South West Native Title Settlement) and the settlement between the Western Australian Government and the claimant group became effective in January 2021. The consequence of this settlement is that an extensive and ongoing benefits package was provided by the West Australian Government to the claimant group and all native title claims over lands in the south west of Western Australia were released.
Obligations to enter into Aboriginal heritage agreements to protect heritage sites continue to apply to any activities in the settlement area.
To meet the then-applicable requirements for the Project, Newmont entered into a voluntary agreement with the claimant group in 2006. The Moorditj Booja Community Partnership Agreement has an end date of 31 December 2025.
3.8 Water Rights
Water rights are discussed in Chapter 15.7.
| | | | | | | | |
Date: February, 2022 | | Page 3-10 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Figure 3-2: Surface Rights Plan
| | | | | | | | |
Date: February, 2022 | | Page 3-11 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
3.9 Royalties
Production royalties are payable to the WA government and are included in the net smelter return (NSR) cut-off determination. Royalty payments were first incurred in the second half of 2009, and comprise:
•Copper royalty of 5% of the realized copper value, calculated in US$ and payable in AU$;
•Silver royalty of 2.5% of the realized silver value, calculated in US$ and payable in AU$;
•Gold royalty of 2.5% of the gold value, except that no gold royalty is payable in respect of the first 2,500 oz of payable gold produced in any financial year.
3.10 Encumbrances
In accordance with contractual arrangements with the Worsley Joint Venture Newmont, the bauxite within the area of its operations is reserved for the benefit of the Worsley Joint Venture and Newmont is required to conserve this bauxite, including through mining and stockpiling bauxite on behalf of the WJV. Certain of its tenements also contain a reservation of bauxite in favor of Alcoa Australia.
3.11 Permitting Requirements
Permitting and permitting conditions are discussed in Chapter 17.5 of this Report. The operations as envisaged in the LOM plan are either fully permitted, or the processes to obtain permits are well understood and similar permits were granted to the operations in the past, such as TSF raises.
There are no current material violations or fines, as imposed in the mining regulatory context of the Mine Safety and Health Administration (MSHA) in the United States, that apply to the Boddington Operations.
3.12 Significant Factors and Risks That May Affect Access, Title or Work Programs
The following significant factors or risks may affect access, title, or right or ability to perform work at the Project:
•Accurate closure cost provisioning, management of rehabilitation stockpiles (topsoil, gravels etc.), changes in design of facilities;
•Waste rock management and generation of acid rock drainage (ARD);
•Unapproved clearing of native vegetation;
•Incorrect disposal of waste resulting in contamination of local area;
•Spread of declared weed species or forest dieback disease;
•Failure to obtain approvals and amendments to licenses within desired timeframes;
•Failure to fully understand regional groundwater interactions and local dewatering activities impact on the local river system;
| | | | | | | | |
Date: February, 2022 | | Page 3-12 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
•Breach of commitments with the Moorditj Booja Community Partnership Agreement;
•Operations impacting sacred sites;
•Reputational damage with local community if complaints or concerns are not addressed.
There is a risk to the Boddington Operations overall if the Worsley JV were to fail to renew the mining leases, as Newmont’s interest relies on the existence of valid mining tenure.
To the extent known to the QP, there are no other known significant factors and risks that may affect access, title, or the right or ability to perform work on the properties that comprise the Boddington Operations that are not discussed in this Report.
| | | | | | | | |
Date: February, 2022 | | Page 3-13 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
4.0 ACCESSIBILITY, CLIMATE, LOCAL RESOURCES, INFRASTRUCTURE AND PHYSIOGRAPHY
4.1 Physiography
The Boddington Operations are located on the Darling Plateau in an area of deeply weathered, undulating landscape that ranges from 200–500 meters Relative Level (mRL). Local relief varies by about 100 m, with shallow valley floors adjacent to broadly convex hills.
The mine is located in the catchment area of Thirty Four Mile Brook, a tributary of the Hotham River, which itself flows into the Murray River and then into the Peel Harvey Inlet.
The mining leases are located largely on private forested land typical of the eastern Jarrah (a type of eucalyptus) forest. The forests were subject to selective logging for many decades. Land to the west of the Project area is State Forest, whereas much of the land to the south was cleared for agriculture, and is commonly used for sheep grazing and mixed cropping.
4.2 Accessibility
The township of Boddington is located 130 km southeast of Perth, is 14 km due west of the main Perth–Albany Highway, and is accessed by an all-weather sealed road. The operations are 17 km northwest of Boddington, and are accessed via a sealed road from the township. Within the operations areas, high-use road surfaces are sealed, and the remaining road types are finished with a gravel surface.
The port of Bunbury is used as the trans-shipment point for copper concentrates produced from the mine, and is approximately 170 km southwest of Perth, and approximately 175 km southwest of the operations area.
4.3 Climate
The climate is Mediterranean, with hot, dry summers and cool, wet winters. The coldest month is July (average 4.5ºC), and the warmest is January (average 32ºC). Rainfall averages approximately 780 mm/a, with most precipitation falling between April and October.
Mining operations are conducted year-round.
4.4 Infrastructure
Perth is the main source of supplies, and has a large, specialized infrastructure for mining support. There are adequate schools, medical services and businesses to support the work force. A skilled and semi-skilled mining workforce was established in the region as a result of on-going mining activities. Workers commute from Boddington and surrounding settlements to the mine site.
The mine site has medical facilities to handle emergencies. In addition, medical facilities are available in Perth to support the mine’s needs.
| | | | | | | | |
Date: February, 2022 | | Page 4-1 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
The Boddington Operations currently have all infrastructure in place to support mining and processing activities (see also discussions in Chapter 13, Chapter 14, and Chapter 15 of this Report). These Report chapters also discuss water sources, electricity, personnel, and supplies.
| | | | | | | | |
Date: February, 2022 | | Page 4-2 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
5.0 HISTORY
The ownership changes and ownership history for the operations is summarized in Chapter 3.3.
The mine has had two operating phases. From 1987–2001, open pit mining exploited gold in oxide resources in laterite from the original Boddington laterite pit and satellite deposits. A small decline was used to extract gold in quartz veins in the north of the Boddington area. Mining ceased in 2001, the plant and infrastructure were decommissioned, and redundant equipment was sold and removed from site.
Feasibility studies during the 1990s and early 2000s examined the economics of mining low-grade hard rock mineralization within the bounds of the former Boddington laterite pit. Mining recommenced in 2009.
In 2012, evaluations were undertaken to establish the biggest possible pit scenario for permitting purpose; in this scenario, the mine life would potentially extend until 2041.
In 2014, the life-of-mine (LOM) extension project received regulatory approval and the mining proposal approval was granted in 2015. An area of mineralization, termed the CV1 Conveyor Saddle, separates North Pit from South Pit, and would only be mined in times of high gold prices as it currently does not meet reasonable prospects of economic extraction at the gold price forecast in this Report.
Table 5-1 summarizes the exploration and development history of the Boddington Operations.
| | | | | | | | |
Date: February, 2022 | | Page 5-1 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Table 5-1: Exploration and Development History Summary Table
| | | | | | | | |
Year | Company | Note |
1975 | Geological Survey of Western Australia (GSWA) | Conducted a geochemical prospecting program; identified anomalous Au, As, Cu, Pb, Mo, and Zn in a zone about 5 km long and 500 m wide area within the northern extent of the Saddleback Greenstone Belt |
1980 | Reynolds Australia Mines | Explored a significant gold-mineralized zone in an area within the geochemical anomaly |
1982–1985 | BGMJV | Drill testing, mineral resource and ore (mineral) reserve estimates, mining studies, environmental studies, applications for environmental approvals |
1983 | Discovery of an isolated area of supergene enriched copper-gold mineralization within the oxide profile below the water table |
1986–1987 | Alcoa of Australia Limited | Feasibility studies on Hedges area, a northern continuation of the Boddington deposit |
1987 | BGMJV | Open pit mining commenced at Boddington |
1988 | Alcoa of Australia Limited | Open pit mining commenced at Hedges |
1990 | BGMJV | Discovery of high-grade gold-bearing quartz veins in the northern section of the deposit within oxide and bedrock zones |
1991 | Construction of supergene plant |
1992 | Construction of Jarrah Decline to access the high-grade Jarrah quartz veins |
1993–2001 | Open pit mining of six satellite deposits |
1994 | Wandoo low-grade deposit identified |
1997 | Completion of underground mining on the Jarrah quartz veins. Feasibility study on Wandoo South |
1998 | Purchase of Hedges (now Wandoo North) |
2000 | Update of feasibility study using Wandoo South and Wandoo North |
2001 | Oxide resources depleted, mine placed on care and maintenance |
2002 | Newmont | Acquired Normandy Mining interest in BGMJV |
| | | | | | | | |
Date: February, 2022 | | Page 5-2 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
| | | | | | | | |
2003 | BGMJV | Updated feasibility study assuming open pit mining and conventional crush–mill–float processing for copper and cyanide leach processing for gold, focusing on Wandoo South and Wandoo North |
2006 | Board approval of open pit mining operations |
2006 | Regulatory approval of open pit mining operations |
2006 | Newmont | Acquired Newcrest interest in BGMJV |
2009 | Acquired remaining interest in Boddington from AngloGold Ashanti. Commercial production |
2012 | Evaluated combining the North and South Wandoo open pits to extend mine life |
2012 | Project receives interim regulatory approval |
2015 | Life-of-mine extension project receives regulatory approvals Cutback S05A started |
2016 | Highest record gold production in a year (813 koz) Reached cumulative 5 Moz gold produced |
2018 | Mill reached name plate capacity of 40 Mt/a Cutback S09A started |
2019 | D6 water storage reservoir receives regulatory approvals Cutback N03 completed Cutback S04 completed Ex-pit mined, since 2007, reached 1 Bt |
2020 | Mineral reserve addition to the North Pit Board approval for autonomous haul system implementation |
2021 | Full autonomous truck fleet roll out at October 5, 2021 D6 water storage reservoir construction completed |
| | | | | | | | |
Date: February, 2022 | | Page 5-3 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
6.0 GEOLOGICAL SETTING, MINERALIZATION, AND DEPOSIT
6.1 Deposit Type
The deposit style is still somewhat controversial. Features consistent with porphyry-style mineralization, classic orogenic shear zones, and intrusion-related gold–copper–bismuth mineralization, are all recognized, giving rise to a variety of genetic interpretations.
Boddington does not fit any classic Archean orogenic gold deposit model, having a general lack of quartz veins and iron carbonate alteration, a copper ± molybdenum ± bismuth association, zoned geochemical anomalism, and evidence of high-temperature, saline, ore-forming fluids. Detailed petrographic, geochemical and melt inclusion studies suggest a late stage ~2,612 Ma, monzogranite intrusion as one of the principal sources of the mineralizing fluids. However, there is also local evidence for older, perhaps proto-ore, porphyry-style copper ± gold in the dioritic intrusions and patchy, locally high-grade, orogenic-style gold mineralization associated with enclosing shear zones and brittle-style deformation, which was focused on the relatively competent dioritic intrusions (Turner et al., 2020).
6.2 Regional Geology
The Boddington deposit is hosted within the Wells Formation in the Saddleback Greenstone Belt, which lies in the southeastern corner of the Archaean Yilgarn Craton (Figure 6-1).
The Saddleback Greenstone Belt comprises a steeply-dipping and extensively faulted sequence of sedimentary, felsic to mafic volcanic and pyroclastic rocks that were metamorphosed to greenschist–amphibolite facies. The belt is approximately 50 km long, 8 km wide, and is surrounded by granitic and gneissic rocks. Age dates range from 2,715–2,690 Ma.
The Saddleback Greenstone Belt was subdivided into three formations (Wilde, 1976; Figure 6-2):
•Hotham Formation: Metasedimentary rocks; restricted to the southwestern part of the Saddleback Greenstone Belt;
•Wells Formation: Felsic to intermediate volcanic rocks and associated granitoid intrusions. This formation is the main host to economic mineralization at Boddington;
•Marradong Formation: Meta-basaltic lavas and related doleritic/gabbroic intrusions. This formation includes a significant number of ultramafic intrusions in the northern half of the Saddleback Greenstone Belt.
These units are cut by at least three generations of Proterozoic dolerite dykes.
The greenstones were emplaced in an island arc setting. Ductile deformation followed, then a second period of supracrustal deposition, again probably in an island arc setting. This second phase was accompanied by coeval granodiorite–tonalite intrusion. Greenschist facies metamorphism followed, and all rocks were affected by brittle–ductile faults.
A late monzogranite intrudes the greenstone belt just east of the mine area and is attributed to melting of mid-crustal rocks in an intraplate setting.
| | | | | | | | |
Date: February, 2022 | | Page 6-1 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Figure 6-1: Regional Geology Setting
Note: Figure from Turner et al., (2020).
| | | | | | | | |
Date: February, 2022 | | Page 6-2 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Figure 6-2: Regional Geology Map
Note: Figure from Turner et al., (2020).
| | | | | | | | |
Date: February, 2022 | | Page 6-3 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
6.3 Local Geology
The Wells Formation within the greenstone belt is informally divided into three packages (Figure 6-3):
•‘Lower’ Wells Formation: mixed package of intermediate andesites and diorites with mafic basalts and dolerites;
•‘Main or Central’ Wells Formation: volcanic andesites and intrusive diorites; favorable mineralization host;
•‘Upper’ Wells Formation: predominantly mafic package of basalts and dolerites with minor lenses of intermediate and metasedimentary rock types.
Several structures were identified that are controlling elements on the localization and form of mineralization, these being:
•Northeast-striking fault corridors, which appear to compartmentalize the deposit. These structures appear to have offset favorable host rocks pre-mineralization;
•Intersection of late-stage faults with early ductile quartz–sericite shear zones;
•Intersection of west–northwest or northwest-trending faults with structurally-favorable lithologies;
•Late brittle–ductile west–northwest- or northwest-trending faults that have subvertical dips, which show elevated mineral abundances, and mineralization-related alteration assemblages.
6.4 Property Geology
The Boddington deposit lies within a 6 km strike length of the Wells Formation. For descriptive purposes the deposit is subdivided at approximately 12,200 N into two main centers of bedrock mineralization, referred to as Wandoo North (North Pit) and Wandoo South (South Pit). The deposit area geology is shown in Figure 6-4 and a cross-section is provided as Figure 6-5.
6.4.1 Lithologies
Most of the primary mineralization at Boddington is hosted within intermediate to felsic intrusive, volcanic, and volcano-sedimentary rocks, with approximate dimensions of 9,000–11,000 mE; 8,500–14,500 mN; and -675–324 mRL. The deepest mineralization intercept to date is at approximately 1,219 m. The volcanic rocks are dominated by dacites and andesites.
| | | | | | | | |
Date: February, 2022 | | Page 6-4 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Figure 6-3: Stratigraphic Column Schematic
Note: Figure prepared by Newmont, 2021; modified from Turner et al. (2020).
| | | | | | | | |
Date: February, 2022 | | Page 6-5 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Figure 6-4: Geology Map
Note: Figure from Turner et al. (2020).
| | | | | | | | |
Date: February, 2022 | | Page 6-6 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Figure 6-5: Geological Cross-Section
Note: Figure from Turner et al. (2020). Section location is shown on Figure 6-4.
| | | | | | | | |
Date: February, 2022 | | Page 6-7 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
The Wells Formation is intruded by at least three magmatic suites:
•A suite of quartz-feldspar-phyric diorite, porphyritic diorite, and microdiorite intrusions (Diorite suite) which are spatially linked to the bulk of the Au-Cu mineralization. These were emplaced between 2,714 and 2,691 Ma (Roth, 1992; Allibone et al., 1998; McCuaig and Behn, 1998);
•A separate suite of granodiorite-quartz diorite-tonalite intrusions (Eastern suite), which intrude the Marradong and Wells Formations, is dated at ~2,675 Ma (Allibone et al., 1998);
•The “Late Granite” (Wourahming monzogranite) suite is the final intrusive event at ~2,612 Ma (Turner et al., 2020).
The N05 extended layback, at North Pit, is dominated by diorites, with lesser fragmental volcanic rocks. The diorites at North Pit are mainly porphyritic and generally more felsic compared to the predominantly aphyric diorites of South Pit. A suite of rhyodacitic porphyries are identified at North Pit, but is rarely observed at South Pit.
The South Pit is centered on a composite diorite stock, the Central Diorite, which has a known strike length of approximately 1,200 m and thicknesses varying from 300–600 m. The southern portion of the Central Diorite strikes north, and dips subvertically and steeply to the west, with an apparent southerly plunge. To the north, the strike of the diorite changes from north to northwest, following the orientation of a transecting dolerite dike. The dip changes from westerly, to subvertical, to steeply to the southwest.
The diorite is in contact with three volcanic units:
•Southern volcanic unit: sequence of porphyritic volcanic rocks in the south and west;
•Northern volcanic unit: sequence of tuffaceous volcanic rocks to the northwest;
•Eastern volcanic unit: characterized by aggregated clusters of plagioclase. Separated from the Central Diorite by the Eastern Shear Zone, a north-striking, steeply west-dipping brittle, ductile tectonic feature.
Thin units of fragmental volcaniclastic rocks consisting of angular to well-rounded diorite and andesite clasts ranging from fine ash to agglomerate sizes are common within and around the diorite stock. A series of fine-grained microdiorite dykes, ranging from a few centimeters to several meters wide, cross-cuts andesite, diorite, and fragmental lithologies.
A suite of Proterozoic dolerite dykes with three prominent orientations cross-cuts the entire mine sequence, but does not host any significant mineralization.
6.4.2 Structure and Alteration
The following structural/alteration events were identified at Boddington:
•Early (pre-deformation) albite and biotite–silica alteration associated with the dioritic intrusions was interpreted by Roth (1992) to signify potassic alteration (Turner et al., 2020);
•D1–D2 ductile shearing was accompanied by silica–sericite–pyrite ± arsenopyrite alteration. Lacks significant gold–copper mineralization. Formed north–south-striking sub-vertical to east-dipping broad ductile shear zones;
| | | | | | | | |
Date: February, 2022 | | Page 6-8 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
•D3 northeast-trending ductile shearing produced mylonite zones with silica–albite–biotite–pyrite alteration. Associated with development of massive quartz veins in D2 shear zones;
•D4 northwest-trending, brittle-ductile deformation. Late D4 clinozoisite–quartz–chlorite–sulfide veins commonly impart a fine fracture-fill network or mesh texture to the rocks and are generally associated with the bulk of the low-grade gold–copper mineralization. In addition, late D4 actinolite–sulfide veins have a narrow selvage of phlogopite–clinozoisite or quartz–albite, and are associated with zones of higher grade gold and copper (Turner et al., 2020).
6.4.3 Weathering
The laterite zone consists of 1–10 m of topsoil and loose gravel, underlain by 1–2 m of ferruginous duricrust, and a basal zone of 1–10 m of gibbsitic bauxite with goethite, hematite and minor kaolinite. The saprolite zone, 25–80 m thick, typically consists of mottled and ferruginous kaolinitic clays, with preserved rock textures. The saprock zone includes smectite clays, with rock fragments and well preserved textures. The saprock to bedrock transition typically occurs over a few meters.
6.4.4 Mineralization
Two mineralization stages were recognized. The earliest phase consists of widespread silica–biotite alteration and complex quartz + albite + molybdenite ± muscovite ± clinozoisite ± chalcopyrite veins, all of which are variably deformed by ductile shear zones.
The second, major, alteration stage cross-cuts the first, and comprises:
•Quartz + albite + molybdenite ± muscovite ± biotite ± fluorite ± clinozoisite ± chalcopyrite veining;
•Clinozoisite + chalcopyrite + pyrrhotite + quartz + chlorite veins that host low-grade gold–copper mineralization;
•Actinolite + chalcopyrite + pyrrhotite ± quartz, carbonate + biotite veins that host high-grade mineralization.
Gold in the laterite zones occurs in association with iron and aluminum hydroxides. Gold in the saprolite is hosted in primary quartz veins, in clays immediately adjacent to mineralized quartz veins, and in secondary, shallow-dipping, goethitic horizons. Saprock mineralization reflects the mineralization distribution in the underlying bedrock.
Bedrock gold mineralization is hosted in veins, lenses and stockworks. Chalcopyrite and pyrrhotite the dominant sulfides, with lesser pyrite, sphalerite, cubanite, cobaltite, arsenopyrite, pentlandite, covellite, bismuthinite, digenite, marcasite and galena.
Quartz–albite–sulfide veins with coarse molybdenum, a dominant control for molybdenite distribution within the deposit, are found in both the Wandoo North and South areas but are dominant in the South Pit. Non-mineralized, thin felsic and intensely epidote-altered lithologies are seen in the Wandoo North area but are not reported from the South Pit.
Figure 6-6 to Figure 6-11 are plan and cross section images at North Pit, S05A pit and S09A pit displaying gold mineralization trends in blast hole data and exploration drill hole orientations.
| | | | | | | | |
Date: February, 2022 | | Page 6-9 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Figure 6-6: North Pit (N03) Plan View
Note: Figure prepared by Newmont, 2021. Image at 50 m RL.
| | | | | | | | |
Date: February, 2022 | | Page 6-10 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Figure 6-7: North Pit (N03) Section View
Note: Figure prepared by Newmont, 2021. Section line at 13,100 mN.
| | | | | | | | |
Date: February, 2022 | | Page 6-11 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Figure 6-8: S05A Pit, Plan View
Note: Figure prepared by Newmont, 2021. Image at 50 m RL.
| | | | | | | | |
Date: February, 2022 | | Page 6-12 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Figure 6-9: S05A Pit, Section View
Note: Figure prepared by Newmont, 2021. Section line at 10,950 mN
| | | | | | | | |
Date: February, 2022 | | Page 6-13 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Figure 6-10: S09A Pit, Plan View
Note: Figure prepared by Newmont, 2021. Image at 250 m RL.
| | | | | | | | |
Date: February, 2022 | | Page 6-14 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Figure 6-11: S09A Pit, Section View
Note: Figure prepared by Newmont, 2021. Section line at 9,300 mN.
| | | | | | | | |
Date: February, 2022 | | Page 6-15 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
7.0 EXPLORATION
7.1 Exploration
7.1.1 Grids and Surveys
Mining operations use a mine grid. The local mine grid was required for two reasons:
•Geological: to rotate the north orientation by approximately 40º so that the grid would align with the geology and topography of the area. Initial outcrops were running along a strike of 320º;
•Survey: to create a false easting and northing at the origin of the site (10000E and 10000N). This allows a simplified coordinate system to be used and creates a grid with a scale factor of exactly 1, so there are no adjustments to any distances measured.
The grid was created from a calibration using the Map Grid of Australia Datum (MGA94, Zone 50). The vertical datum remained the same with the Australian Height Datum (AHD) used with reference to the Ausgeoid09. RL 0 for this datum is mean sea level.
The topographic surface used to delimit block models is constructed from an as-mined surveyed pickup that is updated on a monthly basis.
7.1.2 Geological Mapping
Very limited amount of bedrock exposure in the Project area restricted surface mapping, while most geological mapping was derived from logging drill core and drill chip samples.
Structural mapping is routinely completed of highwalls by the geotechnical department and blast holes are mapped for dolerite and oxide by mine geologists.
During 2020, a consultant was engaged to complete a review on structural controls on mineralization in the South Pit and exploration drill hole orientations. A third-party consultant reviewed blast hole and core data and completed targeted highwall mapping during his investigation. The primary focus of the review was S09A. The study concluded that the exploration drill hole orientation was sub-optimal to the main mineralization trend. This observation was accounted for in subsequent resource model updates. Drill hole orientation in S05A was considered to be acceptable.
7.1.3 Geochemistry
Boddington was discovered in 1980 by two surface traverses which collected lateritic samples across the Greenstone Belt in an area of geochemical anomalism identified by the GSWA (1978).
Geochemical sampling was completed as part of the initial, first-pass exploration program, and was supplemented by data obtained from drilling and mining operations. Samples collected during early programs included stream sediments (bulk-leach extractable gold or BLEG), soil (mobile metal ion -MMI) rock chip. Later, samples were collected using Newmont’s proprietary deep sensing geochemistry approach.
| | | | | | | | |
Date: February, 2022 | | Page 7-1 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
After the initial discovery of Boddington, further soil samples were collected on grids ranging from 50 x 100 m out to 200 x 200 m over regional areas of the Saddleback Greenstone Belt. Additional soil samples were collected in 2020–2021 and results will be used for exploration target generation within the Saddleback Belt.
7.1.4 Geophysics
Airborne and ground geophysical surveys were completed as part of initial and greenstone-belt-wide exploration activities (Figure 7-2 and Table 7-1).
To date, geophysics at the Boddington Gold Mine and surrounding area has consisted of aeromagnetic/radiometric surveys, test surface time-domain electromagnetic (TDEM) and induced polarization/resistivity surveys, regional and semi-detailed gravity surveys, mise-a-la-masse survey, downhole TDEM surveying wireline logging of selected deep holes.
The aeromagnetic and radiometric data are primarily of use in mapping lithology and structure. Geological noise in the form of numerous dolerite dykes and what appears to be maghaemite in the laterites makes interpretation of the magnetics somewhat problematic. There are no magnetic minerals associated with the mineralization.
The regional gravity broadly maps out the ultramafic/mafic units within, and the extent of, the Saddleback Greenstone Belt.
The laterite-hosted gold mineralization does not have associated with it any other mineralization or alteration that maybe detectable or mappable using geophysical techniques, hence is not amenable to geophysical exploration. The downhole wireline logs indicate resistivity lows and EM conductivity highs associated with primary mineralization. These are inferred to be due to presence of sulfides and or the development of secondary porosity associated with faults. The mise-a-la-masse clearly indicates that mineralization at one prospect, Blob/Son of Blob, is detectable using downhole to surface direct current electrical techniques. The downhole transient electromagnetic surveys indicate these zones are not sufficiently conductive to produce a response to transient electromagnetic techniques.
The induced polarization tests at the selected prospect, Jarrah, were contaminated by the presence of powerlines and fences, and invalidated the results. However, there is enough evidence by way of the presence of disseminated sulfides associated with higher-grade primary mineralization to infer it would respond to this technique.
Geophysics is used in conjunction with other geological datasets to develop exploration targets in Newmont’s tenement package.
| | | | | | | | |
Date: February, 2022 | | Page 7-2 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Figure 7-1: Gravity Image
Note: Figure prepared by ___
| | | | | | | | |
Date: February, 2022 | | Page 7-3 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Table 7-1: Geophysical Surveys
| | | | | | | | | | | |
Survey | Type | Date | Comment |
Airborne | Aero mag | 1982 | 250 m and 500 m line spacing, 100 m flying height |
Aero mag | 1989 | 100 m and 250 m line spacing, 80 m flying height |
Aero mag | 1993 | 3,220 line km at 50 m and 100 m line spacing, 50 m flying height |
Aero mag | 1996 | 8,290 line km at 50 m and 100 m line spacing, 60 m flying height |
Gravity | 2020 | 2,184 line km at 200 m line spacing, 80 m flying height |
Ground | Gravity | 1993 to 2008 | 5,243 stations with varying station spacing in five separate data collection campaigns, comprising 3,030 regional gravity stations and 2,213 detailed stations |
IP | 1999 | 2.1 km of dipole-dipole, 100 m electrode spacing. 0.36 km2 coverage of gradient array |
TDEM | 1999 | Fixed loop–Jarrah–13500N–14300N, 9800E–11000E; Moving loop–Jarrah–13550N–13750N, 10000E–11000E; Fixed loop–Mallee–12200N–13000N, 11400E, 12125E; Moving loop–Mallee–12450N and 12850N, 11400E–12200E and 11400E–12000E |
Wireline Logging | 2000 | Natural gamma, magnetic susceptibility, resistivity, EM conductivity. Holes logged: WBD12500-008, 300 m; WBD12770-003, 294 m; WBD13985-002, 737 m; WBD13485-001, 880 m; WBD13365-001, 819 m |
Drill hole TDEM | 2001 | WBD12770, WBD13080, WBD13485, WBD13365 |
Mise-a-la-masse | 2001 | Three lines surveyed; electrodes at WBD12770–120 m; WBD12770–246 m; WBD13080–312 m. Area of the survey encompassed by 9400E–9800E, 12500N–13300N, approximately 0.24 km2 |
MIMDAS | 2004 to 2006 | 97.5 line km of data collection. 50 m and 100 m dipole spacing and 175–200 m line separation. Completed 10 km at Conveyor, 12.5 km at Hume Tank; 6 km at Eastern Southern Diorite Deeps and 6 km at South Southern Diorite Deeps; 12 km plant site and 12.5 km South Southern Diorite Deeps; 38.4 km WRSFs. |
Note: MIMDAS = Mt. Isa Mining Distributed Acquisition System; IP = induced polarization; TDEM = time-domain electromagnetic; WRSF = waste rock storage facility.
7.1.5 Petrology, Mineralogy, and Research Studies
Since 1980, a number of structural, petrology, mineralogy, lithogeochemical and research studies were completed on the Boddington Operations. Typically, petrological and mineralogical studies were completed in support of metallurgical investigations to determine the size, location and minerals associated with gold particles. Transmitted and reflected light petrology, X-ray detection, X-ray fluorescence, scanning electron microscopy, panning, and fluid inclusion thermometry were conducted to learn more about the metal paragenesis, gold-bearing species, and conditions of formation. Multi-element studies were used on drill core to provide multi-element data to support interpretative multi-element geochemical models.
Three honors theses, two masters theses and one doctoral thesis were completed on deposit aspects. A second doctoral study is currently underway in association with the University of Western Australia.
| | | | | | | | |
Date: February, 2022 | | Page 7-4 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
7.1.6 Qualified Person’s Interpretation of the Exploration Information
The Saddleback Greenstone Belt has been extensively explored for over 50 years, and a considerable information database has developed as a result of both exploration and mining activities.
The primary exploration method is core drilling and assay collection. However, advancements in geophysics and geochemistry, together with regional geological and structural interpretations have improved the amount and quality of data that can be used for exploration vectoring and geological modelling. The geophysical and geochemical information is integrated with the drill hole database to improve deposit model interpretations.
7.1.7 Exploration Potential
The Saddleback Greenstone Belt was discovered in the late 1970s and therefore is relatively ‘young’ in comparison to mining and exploration of other greenstone belts in the Yilgarn Craton.
Exploration in the Saddleback Greenstone Belt in terms of an ability to prioritize anomalies and prospects, was limited by the level of understanding in respect of the geology, structure and the relationships these have with geochemistry, regolith/landform evolution and geophysics. There is limited outcrop of basement lithologies throughout the greenstone belt. Aspects of the geology were covered by numerous investigations, but virtually all of these have focused on the Boddington gold deposit and immediate surrounds.
Exploration historically has focused on exploring for both ‘Boddington-style’ and ‘orogenic’ systems as it was documented that the Boddington deposit is likely a hybrid hydrothermal systems with characteristics of both, and also intrusion related characteristics. Outside the mine, there is evidence of orogenic gold veins and intermediates hosting actinolite–clinozoisite–sulfide mineralization.
More recently, exploration was re-invigorated throughout the greenstone belt by Newmont with the inclusion of new district scale datasets, including an airborne gravity survey flown over the Saddleback Greenstone Belt in 2020 and the district-scale deep sensing geochemistry (DSG) program completed in 2020–2021. The combination of geophysics and surface geochemistry to assist with understanding what lies beneath the regolith has aided in developing the geological framework of the Saddleback Greenstone Belt. The datasets are assisting with recognizing new belt-scale lineaments and felsic intrusions, similar to the monzogranite possibly associated with gold mineralization at Boddington, which could host additional Boddington-style mineralization.
A number of possible cutbacks were identified adjacent to the current mine plan that may represent upside potential for the operations if these areas can be included in the LOM plan.
7.2 Drilling
7.2.1 Overview
| | | | | | | | |
Date: February, 2022 | | Page 7-5 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
7.2.1.1 Drilling on Property
Approximately 159,490 drill holes were completed by December 31, 2021, for about 3.80 Mm of drilling as summarized in Table 7-2. Drill methods included core, reverse circulation (RC), aircore (AC), rotary air blast (RAB) and vacuum.
Drilling that supports the 2021 mineral resource and mineral reserve estimates consists of core and RC drill holes, and totals 7,431 for 1,445,163 m (Table 7-3).
Drill collar locations are shown on a Project-basis in Figure 7-2 and Figure 7-3 and the collars of those drill holes used in mineral resource estimation are shown in Figure 7-4.
7.2.1.2 Drilling Excluded For Estimation Purposes
Drilling excluded from the resource estimate largely comprises historical low-quality holes, grade control drilling from historic operations, and drilling related to the bauxite deposits and operations. Most excluded holes are short, within the oxide zone, and do not intersect the fresh rock that is the focus of modern gold operations.
7.2.2 Drill Methods
Vacuum, RAB and aircore drilling were primarily used as a first-pass evaluation tool of soil sample anomalies to bedrock. RC drilling was used as a mineral resource delineation tool from Project inception to 2000, and a mineral reserves infill tool from 2009–2021. Infill RC drilling programs are currently used to increase confidence ahead of mining.
Core drilling is used for exploration purposes and to support resource and reserve estimates, geotechnical investigations, hydrological campaigns, and to infill areas to increase geological confidence ahead of mining. Core drilling was completed in phases, from 1983 to the Report date.
Drill holes classified as core-drilled include both RC pre-collared holes and those wholly drilled as cores. Core drill holes are primarily drilled at NQ2 size (50.6 mm core diameter). Historically, HQ (63.5 mm) and NQ (47.6 mm) sized drill core were completed, with the amount of HQ drilling being variable, depending on ground conditions, requirements for wedge holes and if the hole was required for later installation of piezometers.
7.2.3 Logging
Vacuum drill holes were logged for lithology; RAB and aircore drill holes were also logged for alteration, veining, and mineralization.
RC logging records lithology, alteration, and mineralization.
| | | | | | | | |
Date: February, 2022 | | Page 7-6 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Table 7-2: Property Drill Summary Table
| | | | | | | | |
Drill Type | Number of Holes | Drill Meters |
Bore | 13 | 1,233 |
Unknown | 78 | 1,705 |
Aircore | 22,168 | 877,588 |
Vacuum | 12,127 | 114,851 |
Blast | 56,252 | 241,261 |
Core | 3,924 | 1,117,558 |
Geotech | 387 | 156,465 |
Hammer (RC) | 4,294 | 432,135 |
RAB | 2,083 | 69,306 |
Underground | 448 | 29,786 |
Grade control (RC) | 57,624 | 899,050 |
Piezo | 92 | 4,205 |
Null | 1,855 | 24,924 |
Total | 159,490 | 3,970,067 |
Note: Metreage has been rounded; totals may not sum due to rounding.
Table 7-3: Drill Summary Table Supporting Mineral Resource Estimates
| | | | | | | | |
Drill Type | Number of Holes | Drill Meters |
Core | 3,659 | 1,089,787 |
RC | 3,739 | 347,468 |
Geotech core | 33 | 7,908 |
Total | 7,431 | 1,445,163 |
Note: Metreage has been rounded; totals may not sum due to rounding.
| | | | | | | | |
Date: February, 2022 | | Page 7-7 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Figure 7-2: Regional Drill Collar Location Plan
Note: Figure prepared by Newmont, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 7-8 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Figure 7-3: Regional Drill Collar Location Plan in Operations Vicinity
Note: Figure prepared by Newmont, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 7-9 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Figure 7-4: Drill Collar Location Plan for Drilling Supporting Mineral Resource Estimates
Note: Figure prepared by Newmont, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 7-10 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Historically, geological logging of core recorded lithology, alteration, mineralization, and structure in separate ‘passes’ into separate logging templates. Currently, lithology, structure and alteration are logged directly into the database via separate tables. Mineralization is incorporated into the alteration table.
7.2.4 Recovery
Recoveries were not routinely measured for RC drilling. Core recoveries are typically 100%.
7.2.5 Collar Surveys
Historically aircore, RAB, core, and RC (hammer) holes were predominantly picked up by survey after they were drilled.
Currently, core and RC collars are picked up the survey team using differential global positioning system (DGPS) instruments.
Vacuum holes are pegged by survey before drilling and drilled within 1 m of the collar location peg.
7.2.6 Down Hole Surveys
Not all RC drill holes were downhole surveyed. RC drill holes at the Hedges mine did not have downhole surveys, as was the case with BGMJV RC drill holes prior to 1995. RC drill holes from 1995–2007 were surveyed every 50 m using a single-shot Eastman camera. From 2007 until 2020, RC holes were surveyed using Reflex single- or multi-shot electronic survey tools with surveys completed at the collar and every 30 m downhole. Currently RC holes are surveyed every 30 m using a north-seeking gyro.
Historically, all core drill holes were typically downhole surveyed at 50 m intervals except where hole deviation requirements meant additional surveys for close monitoring during drilling. Surveying was conducted with a single-shot Eastman camera. During 2006, downhole surveys were routinely taken at 50 m intervals using a single-shot Eastman camera. In 2007, this was adjusted to 30 m intervals for the first part of the drill hole until a reasonable hole trace was established and then changed to 42 m intervals by the supervising geologist. A Reflex EZ digital camera was introduced in 2007, and used until 2017. Since 2018 core holes were surveyed using a north-seek gyro every 30 m.
Quality assurance and quality control (QA/QC) readings were taken using a gyro instrument by an independent business partner and compared to the original survey conducted by the drilling business partner.
Declination corrections were applied to the downhole survey data as required. The same declination correction factors were used for core and RC drilling.
7.2.7 Blast Hole Drilling
Blast hole samples are currently used to construct the ore control models that are used for material classification. The approximately 6 kg blast hole samples are collected using a hand-held auger from blast hole cones. Blast holes are drilled for drill-and-blast purposes on a 5.2 x
| | | | | | | | |
Date: February, 2022 | | Page 7-11 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
5.2 m pattern for ore and 5.7 x 5.7 m pattern for waste for each shot on the pit floor. Blast holes are primarily drilled using Atlas Copco DML and PV235 rigs with a hole diameter of 229 mm. Collar location are determined using a rig-based GPS system with collar locations reviewed by the survey department prior to use in ore control models.
7.2.8 Comment on Material Results and Interpretation
The quantity and quality of the lithological, geotechnical, collar and down-hole survey data collected during the exploration and delineation drilling programs are sufficient to support mineral resource and mineral reserve estimation. The collected sample data adequately reflect deposit dimensions, true widths of mineralization, and the style of the deposits. Sampling is representative of the gold and copper grades in the deposit, reflecting areas of higher and lower grades.
Drilling is normally perpendicular to the strike of the mineralization, but depending on the dip of the drill hole, and the dip of the mineralization, drill intercept widths are typically greater than true widths.
7.3 Hydrogeology
7.3.1 Sampling Methods and Laboratory Determinations
Groundwater monitoring is completed via a network of monitoring bores and grouted multiple vibrating wire piezometer pore pressure monitoring bores, covering all areas of the active mine site (including waste rock dumps and tailings dam areas) and the regional areas peripheral to the mine operations. Monitoring data are collected for the following variables:
•Phreatic water level;
•Pore pressure;
•Varied suites of water quality variables specific to the risk associated to the location of the monitoring bores (e.g., WRSFs, TSFs, process plants).
The groundwater sampling is conducted in accordance with Australian New Zealand Standard AS/NZS 5667.11 with all laboratory samples sent to the National Association of Testing Authorities-certified laboratory, ALS, in Perth, Western Australia. ALS is independent of Newmont.
Complimenting the groundwater monitoring programs are extensive surface water sampling programs focused on regional, mining (WRSFs and drainage), TSFs, and processing areas. The surface water samples are sent to the same laboratory as the groundwater samples with monitoring of water quality variables specific to the risk associated with the sample location.
7.3.2 Comment on Results
Pore pressures and groundwater levels are constantly monitored by use of a series of grouted multiple vibrating wire piezometer bores and standpipe groundwater monitoring bores. Site personnel routinely collect data, analyze time-series data on a monthly basis, and summarize findings in quarterly reports. As required, corporate subject matter experts and/or third party consultants undertake specialized hydrological/geotechnical evaluations.
| | | | | | | | |
Date: February, 2022 | | Page 7-12 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
All surface and groundwater variables are stored in a cloud-based environmental database (Monitor Pro) along with other key environmental monitoring data (e.g., weather, air quality and waste tracking).
To the Report date, the hydrogeological data collection programs have provided data suitable for use in the mining operations, and have supported the assumptions used in the active pits.
7.3.3 Groundwater Models
A numerical groundwater flow model (FEFLOW) was developed for the groundwater and hydrogeological system in the 34 Mile Brook catchment.
7.3.4 Water Balance
A probabilistic water balance (GoldSim) model was developed for the site water balance.
7.4 Geotechnical
Geotechnical data are collected where deemed necessary to provide additional information and to verify ground conditions in the vicinity of the open pits and WRSFs. Core drilling methods are used to collect soil and or rock core. Materials encountered are logged and sampled are selected and recovered for laboratory testing where required.
In addition to information gathered during core drilling, geological structures are mapped and documented continuously as mining progresses in the open pits. This is aided through use of geo-referenced photogrammetry and high-definition point cloud scanning that is used to create digital references of structures modelled.
7.4.1 Sampling Methods and Laboratory Determinations
Laboratory testing includes a variety of tests used to derive engineering characteristics of soils and rock materials. Materials testing for strength and material characterizations include the following:
•Triaxial;
•Unconfined compressive strength;
•Shear strength;
•Tensile strength;
•Soil/material classification tests.
Newmont uses National Association of Testing Authorities-accredited laboratories to ensure adequate quality and integrity of testing procedures and results. A centralized database of material logs is maintained to enable orderly access to information.
| | | | | | | | |
Date: February, 2022 | | Page 7-13 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
7.4.2 Monitoring
Geotechnical systems are implemented and maintained to monitor slope and pit wall deformation. These include the following systems:
•Prism arrays monitored using robotic automated total stations;
•Alarmed slope stability radars which continuously scan pit walls to pick up deformation and provide alerts where required.
In addition to automated monitoring systems, routine visual checks and inspections are carried out across active mining areas.
A rockfall register is maintained to track and document events that may occur within the open pits. This is updated as required during operations and through feedback from site personnel. Known details of seismic events are also recorded within site documentation
7.4.3 Comment on Results
The geological hard rock setting at the Boddington Operations is well understood and displays consistency in the various open pits located on site. Additional testing continues to confirm the consistency of material strengths and parameters.
Some variation of soil strengths is apparent in various locations in the vicinity of operational areas, which is well understood and documented. Where further information is required, additional data may be collected.
To the Report date, the geotechnical data collection programs have provided data suitable for use in the mining operations, and have supported the assumptions used in the active pits.
| | | | | | | | |
Date: February, 2022 | | Page 7-14 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
8.0 SAMPLE PREPARATION, ANALYSES, AND SECURITY
8.1 Sampling Methods
BLEG samples were collected from suitable drainages, as 2–5 kg samples, and placed in pre-numbered calico bags. The sample location was recorded, typically on aerial photographs.
Soil samples were collected as 2 kg samples from 15–20 cm depths in the soil profile, a description recorded, then samples were placed in a pre-numbered calico bag.
Rock chip samples were typically collected as 2–5 kg of grab samples from surface outcrops. Sample locations were recorded, together with a geological description.
Vacuum samples were taken at intervals that varied from 0.5–1.0 m to provide a 150 g sample. RAB samples were collected at intervals ranging from 1–2 m to provide 1–2 kg of sample. Aircore samples were usually 2–5 kg in size and collected on 1–2 m intervals.
Prior to 2008, RC samples were collected in plastic bags on 1 m intervals via a cyclone before sample reduction utilizing a riffle splitter. The samples were composited to 2 m intervals of 4–6 kg. Since 2008, samples are collected on 2 m intervals in a drop box and split using cone splitters on the RC rigs.
Drill core was sawn in half along an orientation line for sampling using either a manual core saw or an automatic core saw. The core was cut such that the orientation line was preserved. Typically, NQ core was sampled on 2 m intervals and HQ core sampled on 1 m intervals. More recently, NQ2 core was sampled on 1 m intervals and cut with automatic saws. Proterozoic dolerites were not completely sampled. Where a dolerite of >3 m thickness is encountered in the drill hole, sampling is conducted such that the sampling will stop at the contacts of the dolerites and a 1 m sample, measured from the dolerite contact, is taken from within the dolerite.
Trenching machine spoil samples were taken from the side of the trench on 2 m spacings as designated by the supervising geologist as part of ore control of clay during the oxide mining phase in the 1980–1990 period.
Currently, ore control models at Boddington are constructed using blast hole samples. Blast hole rigs drill a 229 mm diameter hole approximately 13.5 m deep to form an ~1.5 t cone of rock chips around the hole. This cone of rock chips is sampled using an auger bit connect to a battery-powered hand drill. An auger sample is taken by resting the auger three quarters the way up on the collar, angling the auger 40–60º towards the center then slowly drilling into the collar all the way to the base. The auger is then pushed straight up and slowly pulled out of the collar. The material from the collar will be caught on the flights of the auger bit, this material is spun off into a plastic bucket. This process is followed 6–10 times around the collar at evenly-spaced points until a 6–8 kg sample is collected. The sample is then tipped from the bucket into a pre-numbered and allocated sample bag.
8.2 Sample Security Methods
Sample security at the Project has not historically been monitored. Sample collection from drill point to laboratory relies upon the fact that samples are either always attended to, or are stored in the locked on-site preparation facility, or are stored in a secure area prior to shipment to the
| | | | | | | | |
Date: February, 2022 | | Page 8-1 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
external laboratory. Chain-of-custody procedures consist of filling out sample submittal forms to be sent to the laboratory with sample shipments to ensure that all samples are received by the laboratory.
8.3 Density Determinations
Historically, the Project’s basement in-situ bulk density determinations were collected on a 50 m x 50 m grid across each geological domain. Analabs, an independent analytical laboratory, undertook in-situ bulk density determinations using the immersion method. Downhole geophysical logging on four drill holes in 1995 and eight drill holes in 2000 confirmed the densities determined using the immersion method. Bulk density values ranged from 2.75 t/m3 in volcanic rocks to 3.00 t/m3 in the Proterozoic dolerites.
A total of 4,285 bulk density samples were collected from resource definition and exploration drilling programs during 2006–2011. Samples were analyzed at Genalysis, which is independent of Newmont, using the immersion method.
From 2011–2019, SG samples were taken at approximately 50–60 m intervals from drill core. From 2020 density sample frequency was changed to approximately 10 m intervals. The density is measured on site using the immersion method, and then 10% of the samples are sent to the Intertek laboratory to be checked. All data are stored in the acQuire database.
8.4 Analytical and Test Laboratories
Historically, from 1983 to 2001, sample analysis was performed by several independent laboratories, including Classic Comlabs, Genalysis, Amdel, Bureau Veritas Kalassay, Analabs, Australian Assay Laboratories (AAL) in Perth, and AAL in Boddington. It is not known if the laboratories were certified at the time.
The Boddington mine site laboratory, operational between 1985 and 2001, was owned by AAL from 1985 to December 1995. From December 1995–2001, the laboratory was owned and operated by Analabs. In 1995, the mine laboratory became ISO 9002 accredited. Approximately 80% of the pre-2001 analytical data was completed by the mine laboratory.
There was no drilling in the period 2001–2005, hence no laboratories were in use.
From 2006 onward, routine analysis of samples collected during core drilling programs was undertaken at Intertek Genalysis in Perth. In 2006, Intertek Genalysis was accredited to ISO/IEC 17025, version 2005. Since February 2015, Intertek Genalysis has also conducted assaying of blast hole and RC samples.
UltraTrace Geoanalytical Laboratories (UltraTrace), Perth, acted as the umpire laboratory. During periods where sample turnaround time was paramount, UltraTrace also acted as a primary laboratory. UltraTrace was part of the Amdel Laboratory group, now part of Bureau Veritas, and was accredited to ISO/IEC 17025.
From 2008 to January 2014, ore control and RC samples were sent to the Kalassay laboratory in Perth. Kalassay achieved ISO/IEC 17025 accreditation during 2010. UltraTrace and Kalassay were acquired by the Bureau Veritas group.
| | | | | | | | |
Date: February, 2022 | | Page 8-2 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
8.5 Sample Preparation
Sample preparation is summarized in Table 8-1.
8.6 Analysis
Analytical methods depended on the sample type and laboratory. Geochemical samples were primarily analyzed using bulk-leach extractable gold methods. Trench, vacuum, aircore and RAB samples were analyzed for gold by fire assay with an atomic absorption spectrophotometry (AAS) finish. Copper analysis was by either single acid digestion or three-acid digestion followed by AAS.
For RC and core samples prior to 2006, analysis of gold was by fire assay with either AAS or inductively-coupled plasma atomic emission spectroscopy (ICP-AES). Copper analysis was by either single acid digestion or three-acid digestion followed by AAS. After 2006, the typical analytical suite requested for core comprised:
•Fire assay gold with AAS finish on 50 g charge;
•Multi-element suite using four-acid digest with ICP optical emission spectroscopy (OES)–ICP mass spectrometry (MS) finish for copper, sulfur, arsenic, bismuth, molybdenum, antimony, cadmium and nickel. Cadmium and nickel were only performed on core samples. Molybdenum and antimony assays were discontinued in 2013 for RC holes.
Bureau Veritas Kalassay used a fire assay method and AAS finish for RC samples between 2009–2014.
Multi-element determination was not routinely performed prior to 2006, but rather performed on selected drill holes as part of detailed geological investigations. When used, the multi-element analytical suite requested typically consisted of silver, arsenic, bismuth, cerium, molybdenum, nickel, lead, antimony, titanium, tungsten, yttrium, zinc and zirconium. Multi-element analysis was performed by Amdel in 2004, using ICP-MS and ICP-AES after triple-acid digestion. A second multi-element program was undertaken in 2007 by UltraTrace. The current multi-element suite uses an ICP-MS or ICP-OES finish to achieve the acceptable lower detection levels for the elements critical to predicting concentrate quality such as arsenic and bismuth.
8.7 Quality Assurance and Quality Control
Worsley established a formal QA/QC system in January 1989 that included review of laboratory performance using methods commissioned by Worsley as well as review of the laboratory’s internal systems.
The principal monitoring system prior to June 1995 included internal round robins conducted by the BGMJV, which allowed comparison of the Boddington Laboratory against other laboratories and standards.
Post June 1995, an updated internal laboratory monitoring system (‘C’ Class) was introduced that allowed electronic capture of quality control data and statistical analysis of results. Formal review of these data was undertaken on a month-by-month basis by BGMJV staff.
| | | | | | | | |
Date: February, 2022 | | Page 8-3 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Table 8-1: Sample Preparation Methods
| | | | | | | | |
Laboratory | Sample Type | Preparation Procedure |
Boddington Mine | Core | Crushed to P95 passing 3 mm; pulverized to P95 passing 150 µm |
Intertek Genalysis | Core, blast holes, RC | Crushed to P90 passing 3 mm; pulverized to 95% passing minus 100 µm |
Ultratrace | Core | Crushed to 2.8 mm; pulverized to nominal 95% passing 90 µm |
Bureau Veritas Kalassay | Blast holes and RC | Crushed to nominal 95% passing 3 mm; pulverized to a nominal 95% passing 90 µm. |
Prior to 1993, one standard reference material (standard) was run routinely with each batch of samples, blanks were run on an intermittent basis, and duplicates chosen on the basis that anomalous results were checked. From 1993 until March 1998, one standard, one blank, and six duplicate samples were present in each fire assay batch of 50 samples. From March 1998, each fire assay batch of 50 included two standards, one blank, two duplicates, and two replicates.
Since 2006, standards and blanks were submitted randomly in the sample stream prior to submission to the assay laboratory. The standards and blanks submitted were all commercially purchased, up until 2010 when Boddington started creating standards from mineralization within the mining area. From 2018 there were 10 pulp standards created from Boddington material in use.
For RC samples, rig duplicates were taken at a frequency of one in 20. Duplicate samples for the drill core were not taken; however, typically 5% of the pulps were sent to an umpire laboratory for checking. At the laboratory coarse and pulp duplicates were taken from one in 20 samples. Gold assays above 3 g/t Au were routinely repeated by the laboratory. Laboratory standards were submitted into every assay batch and make up 5% of the samples being analyzed.
The grade control QA/QC process has been in place since 2008. Standards, blanks and field duplicates were preassigned to blastholes at a frequency of one in 40 for field duplicates and blanks and one in 20 for standards.
8.8 Database
All drilling-related data are stored in a Microsoft SQL server database which supports multi-user access, using the acQuire software interface. The database is administered by a dedicated database manager. Survey, geological, topographical and assay data are uploaded in digital format to the database and were supplied in digital format since the early 1990s. Historical drill data were received in hard-copy format, and manually data-entered.
All data are subject to verification checks prior to upload. Checks include coordinates outside the limits preset for that grid, geology, samples and surveys beyond the end of hole depth in the collar table, that survey dips are restricted to be between 90 and -90 and assay data/sample ID checks.
Data imported into the database must go through validation steps before being merged. The validation scripts are run on collar, survey, geology, and assay tables.
| | | | | | | | |
Date: February, 2022 | | Page 8-4 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
8.9 Qualified Person’s Opinion on Sample Preparation, Security, and Analytical Procedures
The sample preparation, analysis, quality control, and security procedures used by the Boddington Operations have changed over time to meet evolving industry practices. Practices at the time the information was collected were industry-standard, and frequently were industry-leading practices.
The Qualified Person is of the opinion that the sample preparation, analysis, quality control, and security procedures are sufficient to provide reliable data to support estimation of mineral resources and mineral reserves:
•Drill collar data are typically verified prior to data entry into the database, by checking the drilled collar position against the planned collar position;
•The sampling methods are acceptable, meet industry-standard practice, and are adequate for mineral resource and mineral reserves estimation and mine planning purposes;
•The density determination procedure is consistent with industry-standard procedures. A check of the density values for lithologies across the different deposits indicates that there are no major variations in the density results;
•The quality of the analytical data is reliable, and that sample preparation, analysis, and security are generally performed in accordance with exploration best practices and industry standards;
•Newmont has a QA/QC program comprising blank, standard and duplicate samples. Newmont’s QA/QC submission rate meets industry-accepted standards of insertion rates. The QA/QC data support that there are no material issues with analytical precision or accuracy;
•Verification is performed on all digitally-collected data on upload to the main database, and includes checks on surveys, collar co-ordinates, lithology, and assay data. The checks are appropriate, and consistent with industry standards.
| | | | | | | | |
Date: February, 2022 | | Page 8-5 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
9.0 DATA VERIFICATION
9.1 Internal Data Verification
9.1.1 Data Validation
Newmont personnel regularly visit the laboratories that process Newmont samples to inspect sample preparation and analytical procedures. Observations not in conformity with Newmont procedures are recorded in Project files and communicated to the appropriate laboratory for corrective action to be taken.
The database is checked using electronic data scripts and triggers.
Newmont has conducted a number of internal data verification programs since obtaining its Project interest, which included the following reviews:
•Database, including logging consistency, down hole survey, collar coordinate and assay QA/QC data;
•Sample assay bias investigations between core and RC samples;
•Analytical repeatability reviews;
•Check assay program results;
•Geological procedures, resource models and drill plans;
•Sampling protocols, flow sheets and data storage;
•Trial mining and simulation studies.
9.1.2 Reviews and Audits
Newmont conducts internal audits, termed Reserve and Resource Review or 3R audits, of all its operations. These audits focus on:
•Reserves processes: geology and data collection; resource modelling; geotechnical; mine engineering (long term) for open pit and underground operations; mineral processing (development); sustainability and external relations; financial model;
•Operations process: ore control; geotechnical and hydrogeology (operational); mine engineering (operational) for open pit and underground operations; mineral processing (operational); reconciliation.
The reviews assess these areas in terms of risks to the contained metal content of the mineral resource and mineral reserve estimates, or opportunities to add to the estimated contained metal content. Findings are by definition areas of incorrect or inappropriate application of methodology or areas of non-compliance to the relevant internal Newmont standard (e.g., such as documents setting out the standards that are expected for aspects of technical services, environmental, sustainability and governmental relations) or areas which are materially inconsistent with published Newmont guidelines (e.g., such as guidelines setting out the protocols and expectations for mineral resource and mineral reserve estimation and classification, mine engineering, geotechnical, mineral processing, and social and
| | | | | | | | |
Date: February, 2022 | | Page 9-1 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
sustainability). The operation under review is expected to address findings based on the level of criticality assigned to each finding.
The most recent Boddington Operations 3R audits were conducted in 2012, 2014, and 2019.
The 2019 3R audit found that the Boddington Operations were generally adhering to Newmont’s internal standards and guidelines with respect to the estimation of mineral resources and mineral reserves. The review team identified no material issues with the mineral resource and mineral reserve estimation processes. One moderate-impact issue was noted, in that the cut-off grades for mineral resources and mineral reserves were not significantly different for processing costs and were the same for mining costs. However, the 3R reviewers were of the opinion that the resources cut-off grade needed to include provision for potential increases in mining and processing costs due to the need for additional waste storage capacity, increasing waste haulage distances, and additional tailings storage facility capacity. The team made a number of recommendations for site-based improvements; however, none of these additional recommendations were considered critical to implement. Recommendations included suggestions for improvement in the modelling process, particularly in domaining, closer monitoring of short-term variations to the cost inputs used in mine planning to better refine the cost assumptions, and improvements in short-term mine planning processes.
9.1.3 Mineral Resource and Mineral Reserve Estimates
Newmont established a system of “layered responsibility” for documenting the information supporting the mineral resource and mineral reserve estimates, describing the methods used, and ensuring the validity of the estimates. The concept of a system of “layered responsibility” is that individuals at each level within the organization assume responsibility, through a sign-off or certification process, for the work relating to preparation of mineral resource and mineral reserve estimates that they are most actively involved in. Mineral reserve and mineral resource estimates are prepared and certified by QPs at the mine site level, and are subsequently reviewed by QPs in the Newmont-designated “region”, and finally by corporate QPs based in Newmont’s Denver head office.
9.1.4 Reconciliation
Newmont staff perform a number of internal studies and reports in support of mineral resource and mineral reserve estimation for the Boddington Operations. These include reconciliation studies, mineability and dilution evaluations, investigations of grade discrepancies between model assumptions and probe data, drill hole density evaluations, long-range plan reviews, and mining studies to meet internal financing criteria for project advancement.
9.1.5 Subject Matter Expert Reviews
The QP requested that information, conclusions, and recommendations presented in the body of this Report be reviewed by Newmont experts or experts retained by Newmont in each discipline area as a further level of data verification.
Peer reviewers were requested to cross-check all numerical data, flag any data omissions or errors, review the manner in which the data were reported in the technical report summary, check the interpretations arising from the data as presented in the report, and were asked to
| | | | | | | | |
Date: February, 2022 | | Page 9-2 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
review that the QP’s opinions stated as required in certain Report chapters were supported by the data and by Newmont’s future intentions and Project planning.
Feedback from the subject matter experts was incorporated into the Report as required.
9.2 External Data Verification
Data verification by external consultants or BGMJV partners in support of mine development and operations is summarized in Table 9-1.
Many of the audits were conducted prior to the commencement of the current mining operation in 2009 to ensure that the best possible database, geological interpretations, block models, and resource estimates were available to support investment decisions.
9.3 Data Verification by Qualified Person
The QP performed site visits as discussed in Chapter 2.4. Observations made during the visits, in conjunction with discussions with site-based technical staff also support the geological interpretations, and analytical and database quality. The QP’s personal inspection supports the use of the data in mineral resource and mineral reserve estimation, and in mine planning.
The QP receives and reviews monthly reconciliation reports from the mine site. These reports include the industry standard reconciliation factors for tonnage, grade and metal; F1 (reserve model compared to ore control model), F2 (mine delivered compared to mill received) and F3 (F1 x F2) along with other measures such as compliance of actual production to mine plan and polygon mining accuracy. The reconciliation factors are recorded monthly and reported in a quarterly control document. Through the review of these reconciliation factors the QP is able to ascertain the quality and accuracy of the data and its suitability for use in the assumptions underlying the mineral resource and mineral reserve estimates.
9.4 Qualified Person’s Opinion on Data Adequacy
Data that were verified on upload to the database, checked using the layered responsibility protocols, and reviewed by subject matter experts are acceptable for use in mineral resource and mineral reserve estimation.
| | | | | | | | |
Date: February, 2022 | | Page 9-3 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Table 9-1: External Data Verification
| | | | | | | | |
Year | Company | Note |
2000, 2001, 2002 | Peter Stoker | Audit of assay data |
2001–2002 | AngloGold Ashanti | Audit of database and mineral resource estimates |
2002 | Golder, Newmont, and AngloGold Ashanti | Review of resource models |
2003 | Golder Associates Pty Ltd (Golder) | Audit of assay data, resource sensitivity study |
Quantitative Geoscience | Audit of resource estimates |
BGMJV | Audit of resource estimates and block model |
2004 | Golder | Audit of resource model |
BGMJV | Review of resource estimate and model comparisons |
Newcrest | Review of resource estimate using alternative modelling interpretations |
BGMJV | Sensitivity study using Newcrest alternate model |
2005 | Dr Dominique Francois-Bongarcon (Francois-Bongarcon) | Review of sampling protocols and heterogeneity issues |
2007 | Francois-Bongarcon | Review of assay data |
2007, 2008 | CS-2 | Audit of resource estimates |
2009 | GeoSystems International | Audit of resource estimates |
2010 | AMEC Americas Ltd | Audit of resource estimates and block model |
2017, 2018 | Golder | Audit of resource/reserve estimates, including mine planning, geotechnical and metallurgical aspects |
2021 | SRK Consulting (Australasia) Pty Ltd | Review of ore (mineral) reserves |
| | | | | | | | |
Date: February, 2022 | | Page 9-4 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
10.0 MINERAL PROCESSING AND METALLURGICAL TESTING
10.1 Introduction
During feasibility-stage studies from 1997–2003, several programs of metallurgical testwork were completed on the Boddington deposit. These supported the initial mining phase. A second phase of testwork was conducted in 2008, and a third phase in 2017. The post-feasibility testwork was primarily conducted at AMMTEC in Perth, now ALS Metallurgy.
10.2 Test Laboratories
ALS Metallurgy is an independent commercial metallurgical testing facility. There is no international standard of accreditation provided for metallurgical testing laboratories or metallurgical testing techniques.
10.3 Metallurgical Testwork
Work completed included mineralogy, comminution and high-pressure grind–roll (HPGR) testwork, Bond ball mill, Bond rod mill work index, and abrasion index tests, flotation and leach testwork locked cycle flotation test, scavenger tail leach, cleaner scavenger tail leach); flotation tailings cyanidation testwork; determination of thickening and slurry pumping characteristics; rheology; tailings characterization; and oxygen addition.
Copper concentrate samples were analyzed to provide a better understanding of the deleterious element content and to generate predictive models, based on feed grades, for use in mine scheduling.
The testwork includes but is not limited to:
•Head assay multi-element analysis;
•Ore density;
•Ore moisture;
•Ore bulk density (loose and compacted);
•Unconfined compressive strength;
•Bond crusher work index;
•Abrasion index;
•Bond rod mill work index;
•Bond ball mill work index;
•JK drop weight;
•Mineralogical analysis;
•Locked cycle flotation;
| | | | | | | | |
Date: February, 2022 | | Page 10-1 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
•Large scale kinetic flotation;
•Flash flotation;
•Atmospheric and pressure cyanide leaching;
•Carbon kinetics;
•Gravity recoverable gold;
•Thickening;
•Rheology;
•Slurry agitation;
•Residue pumping;
•Residue characterization.
10.4 Recovery Estimates
Recovery models were developed using known ore parameters to predict plant recovery. In these models, the throughput rate is fixed and the grind size is allowed to vary with ore hardness, resulting in recovery differences in each of the eight geometallurgical domains.
The gold and copper recovery models for the mill are based on head grade.
The forecast LOM gold recovery is 85% and the forecast LOM copper recovery is 82%.
These forecasts do not include the application of recovery degradation to long-term stockpiles of medium-grade ore. Gold recovery is discounted by 3% and copper recovery is discounted by 6% to account for recovery degradation in the business plan. These degradation assumptions were verified by an ongoing stockpile oxidation testwork program.
10.5 Metallurgical Variability
Samples selected for metallurgical testing during feasibility and development studies were representative of the various styles of mineralization within the different deposits. Samples were selected from a range of locations within the deposit zones. Sufficient samples were taken and tests were performed using sufficient sample mass for the respective tests undertaken.
10.6 Deleterious Elements
Since commissioning in 2009, the operation has actively managed the arsenic level in plant feed and, through concentrate blending techniques, controlled the level in copper concentrate shipments to below the penalty rate trigger, hence no penalties were incurred to the Report date. Bismuth is closely associated with gold in the Wandoo ores; however, so it has resulted in penalty levels being exceeded, particularly in the first two years of operation (2009–2011). Most of the high bismuth ores have been processed, resulting in very low to no penalty charges being incurred since 2012.
| | | | | | | | |
Date: February, 2022 | | Page 10-2 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Alumina remains the largest penalty element present in the copper concentrate, with shipments regularly exposed to a penalty adjustment. However, at 4–5% Al2O3 the levels are not far off the trigger point of 3% in most contracts and a modification to the process was made during Q1 2019 with the introduction of the cleaner scalper column which reduces the non-sulfide gangue (i.e., Al2O3) in the concentrate and improves the grade of the concentrate as a result.
10.7 Qualified Person’s Opinion on Data Adequacy
The QP notes:
•Metallurgical testwork completed on the Project is appropriate to establish acceptable processing for the different geometallurgical domains;
•Subsequent production experience and focused investigations guided mill alterations and process changes;
•Testwork was completed on mineralization that is typical of the deposit style. The testwork indicates that gold mineralization is often associated with silver as electrum, copper is primarily contained in chalcopyrite and cubanite, and the ore is primarily hosted within diorite and andesite rocks;
•Testwork programs, both internal and external, continue to be performed to support current operations and potential improvements. From time to time, this may lead to requirements to adjust cut-off grades, modify the process flowsheet, or change reagent additions and plant parameters to meet concentrate quality, production, and economic targets;
•The mill throughput and associated recovery factors are considered appropriate to support mineral resource and mineral reserve estimation, and mine planning;
•The plant will produce variations in recovery due to the day-to-day changes in ore type or combinations of ore type being processed. These variations are expected to trend to the forecast recovery value for monthly or longer reporting periods.
| | | | | | | | |
Date: February, 2022 | | Page 10-3 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
11.0 MINERAL RESOURCE ESTIMATES
11.1 Introduction
The close-out date for the sample database used in Mineral Resource estimation was 13 August 2021, with the resource model dated at 1 October, 2021.
Geological models were constructed by Boddington Operations personnel in Leapfrog, with resource estimates in Vulcan, Supervisor software and proprietary geostatistics workflows developed in conjunction with third-party consultants, Resource Modeling Solutions. Block models were built with cell dimensions that were appropriate to the deposit style, orientation and dimensions of the mineralization. Selectivity during mining, mining method, equipment size and bench height were also taken into account when determining parent cell size.
11.2 Exploratory Data Analysis
Exploratory data analysis was completed to confirm the statistical configuration of gold and copper estimation domains. In addition, contact analysis was conducted to configure the sharing of data where required for estimation purposes across the contact(s) of adjoining domains.
11.3 Geological Models
Models were built for:
•Geology: dolerite lithology and weathering surfaces; gold, copper, sulfur, arsenic, molybdenum and bismuth estimation domains;
•Gold domains are constructed considering structure, alteration but are largely lithology and grade shells;
•Copper: grade shell wireframes constructed by dividing the deposit into four regions based broadly on lithology and, within these regions interpolating high-grade (1,500 ppm) and medium-grade (750 ppm) grade shells;
•In-situ bulk density;
•Geotechnical: five domains in South Pit, six domains in North Pit;
•Structural: 10 major structures in South Pit, and one major structure in North Pit;
•Acid rock drainage: net acid-producing potential (NAPP) estimated.
The data used for the model construction were approved drill holes extracted from the GED. Data were validated using Vulcan ISIS validation tools and on-screen visualization. Issues identified during validation were corrected by the project geologist and posted back to the GED. A final extraction was then made to incorporate the validated data into the geological modeling.
11.4 Density Assignment
In-situ bulk density (density) values were interpolated using ordinary kriging (OK) to provide block estimates when sufficient data were available. Domains that did not contain any in-situ bulk density data were assigned a mean value of 2.75 g/cm3. An in-situ bulk density of 3.00 g/
| | | | | | | | |
Date: February, 2022 | | Page 11-1 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
cm3 was applied to all modelled dolerites. Weathered bulk density values were assigned to regions delineated by the various weathering products.
11.5 Composites
All assay data were composited to 12 m lengths downhole to match the estimated block and bench height and broken on the start of each domain. Composites were length weighted for statistical analysis and estimation. Intervals <6 m were combined with adjacent longer intervals at drill hole ends.
11.6 Grade Capping/Outlier Restrictions
Outlier high grades were statistically determined and grade capped to optimize estimation performance. Capping was defined via exploratory data analysis and applied on the composite data by estimation domain. High-grade cuts were applied to each of the gold, copper, arsenic, bismuth, molybdenum and sulfur domains.
11.7 Variography
Spatial variability of the grades for gold, copper, arsenic, bismuth, molybdenum and sulfur was modeled through directional variography of capped 12 m composites. Blast hole data were used to improve definition of variogram profiles and directions in domains with production coverage.
11.8 Estimation/interpolation Methods
Block models were constructed and estimated in Vulcan software. The final block size used in the resource block model was a regularized size of 20 x 20 x 12 m to match the current SMU. The model was constructed in the Boddington Mine Grid orientation with no additional rotation or sub blocking applied. The blocks were coded for dolerite domains and weathering profile percentages to honor the dilution from dykes and oxidized units.
Ordinary kriged estimates for gold, copper, sulfur, arsenic, molybdenum and bismuth and density were conducted in a separate block model with a parent block size of 10 x 20 x 12 m with sub-blocking to 5 x 5 x 6 m. Domains for each element were also coded into this model. The smaller block model was used for the estimation of the metals and density as it better reflects the resolution of the geological domains. The estimation results were subsequently combined into the larger final block model via a block regularization process.
The estimation methodology included the following:
•Analysis to optimize the parameters used for sample searches, including minimum/maximum number of data, distance to samples, and number of data used per drill hole;
•Domains treated as mix of hard, soft and firm boundaries based on contact analysis;
•Grade interpolations run as two passes, with progressively larger search distances and with protection of blocks estimated in the first pass; The first pass search ellipse is defined from the variogram and scaled to 70 m. The second pass scaled up to 400 m; | | | | | | | | |
Date: February, 2022 | | Page 11-2 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
•The second pass estimate is adequate to prevent unassigned blocks within mining areas.
•Block discretization of 4 x 4 x 1.
Key parameters used in the kriged estimates are provided in Table 11-1.
Grade dilution was applied due to unavoidable mining of small dolerite bodies. Modifying factors were applied to sulfur and copper, based on historical plant reconciliation data.
11.9 Validation
Validation used Newmont-standard methods, including a combination of visual checks, swath plots, global statistical bias checks against input data, alternate estimation methods and reconciliation with historical mine/plant performance.
All models were independently peer reviewed to ensure consistency and standards required to support business and operations planning and public reporting of mineral resources and mineral reserves. Modeling methodologies applied were externally audited in early 2021 by third-party consultants SRK, with no material findings.
The validation procedures indicated that the geology and resource models used are acceptable to support the mineral resource estimation.
11.10 Confidence Classification of Mineral Resource Estimate
11.10.1 Mineral Resource Confidence Classification
Resource classification parameters were based on the results of a 2020 drill hole spacing simulation study in accordance with Newmont standards. Mineral resource classification was undertaken based primarily on drill spacing and number of drill holes used in the estimate (Table 11-2).
A quantitative assessment of geological risk was undertaken using Newmont-standard methods and applied on a block by block basis. Primary risks to resource quality include quantity and spacings of drill data, geological knowledge, geological interpretation and grade estimates. All identified risks are within acceptable tolerances with associated management plans.
Table 11-1: Kriging Estimate Parameters
| | | | | |
Model | Value |
Min # samples | 6 |
Max # samples | 6–8 |
Max # samples per drill hole | 2 |
Min # of drill holes | 3 |
Max # of drill holes | 8 |
Max # of composites per octant | None |
Single/multi pass estimate | Multi |
Large dolerite dilution % post processing | 10% |
| | | | | | | | |
Date: February, 2022 | | Page 11-3 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Table 11-2: Mineral Resource Confidence Classifications
| | | | | |
Confidence Category | Search Configuration |
Measured | 3 holes within average distance <27.5 m |
Indicated | 3 holes within average <55 m |
Inferred | 3 holes within average distance <82.5 m |
11.10.2 Uncertainties Considered During Confidence Classification
Following the analysis in Chapter 11.10.1 that classified the mineral resource estimates into the measured, indicated and inferred confidence categories, uncertainties regarding sampling and drilling methods, data processing and handling, geological modelling, and estimation were incorporated into the classifications assigned. The areas with the most uncertainty were assigned to the inferred category, and the areas with fewest uncertainties were classified as measured.
11.11 Reasonable Prospects of Economic Extraction
11.11.1 Input Assumptions
For each resource estimate, an initial assessment was undertaken that assessed likely infrastructure, mining, and process plant requirements; mining methods; process recoveries and throughputs; environmental, permitting and social considerations relating to the proposed mining and processing methods, and proposed waste disposal, and technical and economic considerations in support of an assessment of reasonable prospects of economic extraction.
Cut-off grades will vary over the life of an open pit, due to variations in capital and operating costs, mine and mill performance, metal prices, exchange rates, and potentially, individual deposit geological and grade characteristics.
Mineral resources considered amenable to open pit mining methods are reported within a mine design that uses a Lerchs–Grossmann pit shell with the parameters set out in Table 11-3.
11.11.2 Commodity Price
Commodity prices used in resource estimation are based on long-term analyst and bank forecasts, supplemented with research by Newmont’s internal specialists. An explanation of the derivation of the commodity prices is provided in Chapter 16.2. The estimated timeframe used for the price forecasts is the 14-year LOM that supports the mineral reserve estimates.
11.11.3 Cut-off
The cut-off grade is defined by a revenue cut-off to account for both copper and gold revenue with two product streams, gold doré and copper concentrate. The block revenue is calculated on the net smelter return (NSR) basis which is the dollar return expected from the sale of the concentrate produced from a tonne of in situ material. The NSR calculation takes into account concentrate shipping and smelting and refining costs. The NSR cut-off for mineral resource reporting is AU$17.34/t milled. The incremental (mill) cut-off is AU$14.99/t milled.
| | | | | | | | |
Date: February, 2022 | | Page 11-4 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
11.11.4 QP Statement
The QP is of the opinion that any issues that arise in relation to relevant technical and economic factors likely to influence the prospect of economic extraction can be resolved with further work. The mineral resource estimates are performed for a deposit that is in a well-documented geological setting; the Boddington deposit has seen nearly four decades of active open pit operations conducted by Newmont and other parties; Newmont is familiar with the economic parameters required for successful operations in the Boddington area; and Newmont has a history of being able to obtain and maintain permits, and the social license to operate, and meet environmental standards in the Boddington area.
There is sufficient time in the 14-year timeframe considered for the commodity price forecast for Newmont to address any issues that may arise, or perform appropriate additional drilling, testwork and engineering studies to mitigate identified issues with the estimates.
Table 11-3: Input Parameters, Open Pit
| | | | | | | | | | | |
Parameters | Item | Unit | Value |
Price | Gold | US$/oz | 1,400 |
Copper | US$/lb | 3.25 |
Exchange rate | | US$:AU$ | 0.75 |
Royalty | Gold | % payable | 2.5 |
Copper | % payable | 5.0 |
Metallurgical recovery | Gold | % | 85 |
Copper | % | 82 |
Mining cost | | AU$/tonne | 4.67 |
Processing cost | | AU$/milled | 10.46 |
General and administrative costs | | AU$/milled | 1.53 |
Sustaining capital | | AU$/milled | 2.20 |
Incremental mineralization costs (closure, haul, conversion) | | AU$/milled | 0.05 |
Overall pit slope angles | | Degrees | Variable, approximately 37–52 |
Cut-off NSR (incremental) | | AU$/t milled | 14.99 |
Cut-off NSR (stockpile) | | AU$/t rehandled | 17.34 |
11.12 Mineral Resource Statement
Mineral resources are reported using the definitions set out in SK1300, on a 100% basis. The reference point for the mineral resources is in situ. Mineral resources are current as at December 31, 2021. Mineral resources are reported exclusive of those mineral resources converted to mineral reserves. Mineral resources that are not mineral reserves do not have demonstrated economic viability.
The estimates for the Boddington Operations are provided in Table 11-4 (measured and indicated; gold) and Table 11-5 (inferred; gold), and Table 11-6 (measured and indicated; copper) and Table 11-7 (inferred; copper).
| | | | | | | | |
Date: February, 2022 | | Page 11-5 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Table 11-4: Measured and Indicated Mineral Resource Statement (Gold)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Measured Mineral Resources | Indicated Mineral Resources | Measured and Indicated Mineral Resources |
Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) |
North Pit | 28,500 | 0.47 | 430 | 61,900 | 0.51 | 1,010 | 90,400 | 0.50 | 1,440 |
South Pit | 67,800 | 0.55 | 1,200 | 118,600 | 0.55 | 2,110 | 186,300 | 0.55 | 3,310 |
Open Pit Sub-total | 96,200 | 0.53 | 1,640 | 180,500 | 0.54 | 3,110 | 276,700 | 0.53 | 4,750 |
Boddington Total | 96,200 | 0.53 | 1,640 | 180,500 | 0.54 | 3,110 | 276,700 | 0.53 | 4,750 |
Table 11-5: Inferred Mineral Resource Statement (Gold)
| | | | | | | | | | | |
Area | Inferred Mineral Resources |
Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) |
North Pit | 1,400 | 0.5 | 20 |
South Pit | 1,900 | 0.5 | 30 |
Open Pit Sub-total | 3,300 | 0.5 | 50 |
Boddington Total | 3,300 | 0.5 | 50 |
Table 11-6: Measured and Indicated Mineral Resource Statement (Copper)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Measured Mineral Resources | Indicated Mineral Resources | Measured and Indicated Mineral Resources |
Tonnage (x 1,000 t) | Grade (Cu %) | Cont. Copper (M lbs) | Tonnage (x 1,000 t) | Grade (Cu %) | Cont. Copper (M lbs) | Tonnage (x 1,000 t) | Grade (Cu %) | Cont. Copper (M lbs) |
North Pit | 28,500 | 0.08 | 50 | 61,900 | 0.10 | 140 | 90,400 | 0.09 | 190 |
South Pit | 67,800 | 0.12 | 170 | 118,600 | 0.12 | 310 | 186,300 | 0.12 | 490 |
Open Pit Sub-Total | 96,200 | 0.11 | 220 | 180,500 | 0.11 | 450 | 276,700 | 0.11 | 670 |
Boddington Total | 96,200 | 0.11 | 220 | 180,500 | 0.11 | 450 | 276,700 | 0.11 | 670 |
| | | | | | | | |
Date: February, 2022 | | Page 11-6 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Table 11-7: Inferred Mineral Resource Statement (Copper)
| | | | | | | | | | | |
Area | Inferred Mineral Resources |
Tonnage (x 1,000 t) | Grade (Cu %) | Cont. Copper (M lbs) |
North Pit | 1,400 | 0.1 | 0 |
South Pit | 1,900 | 0.1 | 0 |
Open Pit Sub-Total | 3,300 | 0.1 | 10 |
Boddington Total | 3,300 | 0.1 | 10 |
Notes to accompany mineral resource tables:
1.Mineral resources are current as at December 31, 2021, and are reported using the definitions in SK1300 on a 100% basis. The Qualified Person responsible for the estimate is Mr. Donald Doe, RM SME, Group Executive, Reserves, a Newmont employee.
2.The reference point for the mineral resources is in situ.
3.Mineral resources are reported exclusive of mineral reserves. Mineral resources that are not mineral reserves do not have demonstrated economic viability.
4.Mineral resources that are potentially amenable to open pit mining methods are constrained within a designed pit . Parameters used are summarized in Table 11-3.
5.Tonnages are metric tonnes rounded to the nearest 100,000. Gold grade is rounded to the nearest 0.01 gold grams per tonne. Copper grade is reported as a %. Gold ounces and copper pounds are estimates of metal contained in tonnages and do not include allowances for processing losses. Contained (cont.) gold ounces are reported as troy ounces, rounded to the nearest 10,000. Copper is reported as pounds. Rounding of tonnes and contained metal content as required by reporting guidelines may result in apparent differences between tonnes, grade and contained metal content. Due to rounding, some cells may show a zero (“0”).
6.Totals may not sum due to rounding.
| | | | | | | | |
Date: February, 2022 | | Page 11-7 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
11.13 Uncertainties (Factors) That May Affect the Mineral Resource Estimate
Factors which may affect the mineral resource estimates include:
•Metal price assumptions;
•Changes to the assumptions used to generate the NSR cut-off;
•Changes to design parameter assumptions that pertain to the conceptual pit shell design that constrain the mineral resources, including changes to geotechnical, mining and metallurgical recovery assumptions, and changes to royalties levied and any other relevant parameters that are included in and impact the NSR cut-off determination;
•Changes in interpretations of mineralization geometry and continuity of mineralization zones;
•Changes to the dilution skin percentages used for large dolerite dykes;
•Assumptions as to the continued ability to access the site, retain mineral and surface rights titles, maintain the operation within environmental and other regulatory permits, and retain the social license to operate.
| | | | | | | | |
Date: February, 2022 | | Page 11-8 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
12.0 MINERAL RESERVE ESTIMATES
12.1 Introduction
Measured and indicated mineral resources were converted to mineral reserves. Mineral reserves are estimated assuming open pit mining.
All Inferred blocks are classified as waste in the cashflow analysis that supports mineral reserve estimation.
The NSR approach is the same as summarized for the mineral resources in Chapter 11.11.3. The NSR cut-off for mineral reserves reporting is AU$17.06/t milled, which includes stockpile rehandle. The incremental (mill) cut-off is AU$14.85/t milled.
12.2 Pit Optimization
For mineral reserves, Newmont applies a time discount factor to the dollar value block model that is generated in the pit-limit analysis, to account for the fact that a pit will be mined over a period of years, and that the cost of waste stripping in the early years must bear the cost of the time value of money.
Pit discounting is accomplished by running the pit-limit “dollar” model through a program that discounts the dollar model values at a compound rate based on the depth of the block. Discounting is applied to future costs as well as future revenues, to represent the fact that mining proceeds from the top down within a phase.
Optimization work involved floating pit shells at a series of gold prices. The pit shells with the highest NPV were selected for detailed engineering design work. A realistic schedule was developed in order to determine the optimal pit shell; schedule inputs include the minimum mining width, and vertical rate of advance, mining rate and mining sequence.
12.3 Optimization Inputs and Assumptions
The mineral reserves LOM schedule was developed using MineSight software and spreadsheet-based scheduling tools.
The mine plan is based on a 42 Mt/a mill throughput. The schedule was developed at an NSR cut-off of AU$17.06/t, incorporating the processing cost, metallurgical recovery, incremental ore mining costs, process sustaining capital and tailings dam related rehabilitation costs. The net revenue calculation assumes a gold price of US$1,200/oz or AU$1,600/oz, and a copper price of US$2.75/lb or AU$3.66/lb. The assumed exchange rate for mineral reserves was 0.75 US$:AU$. Mineral reserves are reported above an NSR cut-off of AU$17.06/t, using the inputs in Table 12-1.
Pit designs are full crest and toe detailed designs with final ramps based on the selected optimum Whittle cones. Pit designs honor geotechnical guidelines with 15.2 m catch berms.
| | | | | | | | |
Date: February, 2022 | | Page 12-1 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Table 12-1: Input Design Parameters
| | | | | | | | |
Item | Unit | Value |
Gold price | AU$/oz | 1,600 |
Copper price | AU$/lb | 3.67 |
Exchange rate | US$:AU$ | 0.75 |
Gold royalty | % | 2.5 |
Copper royalty | % | 5.0 |
Mill throughput | Mt/a | 42 |
Mill recovery gold (average recovery % at LOM grade 0.67 g/t Au) | % | 85 |
Mill recovery copper (average recovery % at LOM grade 0.1% Cu) | % | 82 |
Base processing cost-without rehandle | AU$/t milled | 10.46 |
Sustaining capital (plant and G&A) | AU$/t mined | 1.85 |
incl. CRF = 1.10 | 2.08 |
Site and regional G&A (exclude capital costs) | AU$/t milled | 2.27 |
Incremental ore, resource conversions and closure (LOM–FASB) | AU$/t milled | 0.04 |
Breakeven mill cut-off | AU$/t milled | 14.85 |
Stockpile rehandling | AU$/t rehandled | 1.48 |
Recoveries degradation | AU$/t milled | 0.73 |
Breakeven stockpile cut-off | AU$/t milled | 17.06 |
LOM operating mining cost | AU$/t mined | 4.67 |
Mining capital | AU$/t mined | 0.76 |
incl. CRF = 1.10 | 0.83 |
Note: LOM = life-of-mine; CRF = capital recovery factor; G&A = general and administrative; FASB = Financial Accounting Standards Board.
Newmont updates its LOM plan each year in preparation for the business plan. All aspects of the plan, including pit stage design and sequencing, cut-off optimization and WRSF and stockpiling strategies are reviewed.
The process plant processes higher-grade ores delivered from the mine at an elevated cut-off. The ore between the elevated cut-off and the marginal cut-off is stockpiled for later processing at the end of the mine life.
Most of the ore will be directly fed to the process plant; however, some re-handle is required. Direct feeding to the crusher is constrained by where the ore is located in the open pit and the crusher availability. Some higher-grade ore is stockpiled and fed back to the crusher when required. Approximately 50% of feed is re-handle material from the stockpiles.
12.4 Ore Loss and Dilution
The block models were constructed to include the expected dilution based on mining methods, bench height and other factors. The current mine and process reconciliation support this assumption.
Dilution is applied to the resource model in two manners which result in a cumulative dilution of approximately 10%. Dilution is applied through:
•Reduction of grade associated with small dolerites;
•Expansion of large dolerite waste volumes.
| | | | | | | | |
Date: February, 2022 | | Page 12-2 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
A nominal background gold grade is applied to reduce the grade in the percentage of blocks which contain small dolerites.
Large dolerite dykes are removed from the resource model and contain no ore. Large dolerites are selectively mined, but due to the hardness and negative impact to the mill, accidentally mining dolerites as ore is avoided. A 10% dilution factor is applied to large dolerite volumes to capture the operational constraints.
Blocks containing >50% oxide material are classified as waste and have the grade set to zero.
12.5 Stockpiles
Stockpile estimates were based on mine dispatch data; the grade comes from closely-spaced blasthole sampling and tonnage sourced from truck factors. The stockpile volumes were typically updated based on monthly surveys. The average grade of the stockpiles was adjusted based on the material balance to and from the stockpile.
12.6 Commodity Prices
Commodity prices used in mineral reserve estimation are based on long-term analyst and bank forecasts, supplemented with research by Newmont’s internal specialists. The estimated timeframe used for the price forecasts is the 14-year LOM.
12.7 Mineral Reserve Statement
Mineral reserves were classified using the definitions set out in SK1300, on a 100% basis. The mineral reserves are current as at December 31, 2021. The reference point for the mineral reserve estimate is at the point of delivery to the process facilities. Mineral reserves are reported in Table 12-2 (gold) and Table 12-3 (copper). Tonnages in the table are metric tonnes.
| | | | | | | | |
Date: February, 2022 | | Page 12-3 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Table 12-2: Proven and Probable Mineral Reserve Statement (Gold)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Proven Mineral Reserves | Probable Mineral Reserves | Proven and Probable Mineral Reserves |
Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) |
North Pit | 78,800 | 0.65 | 1,640 | 94,700 | 0.59 | 1,810 | 173,500 | 0.62 | 3,450 |
South Pit | 158,600 | 0.73 | 3,720 | 144,400 | 0.71 | 3,280 | 303,000 | 0.72 | 7,000 |
Open Pit Sub-Total | 237,400 | 0.70 | 5,360 | 239,100 | 0.66 | 5,090 | 476,500 | 0.68 | 10,450 |
Stockpile Sub-Total | 2,600 | 0.68 | 60 | 79,100 | 0.43 | 1,090 | 81,800 | 0.44 | 1,140 |
Boddington Total | 240,100 | 0.70 | 5,420 | 318,200 | 0.60 | 6,170 | 558,300 | 0.65 | 11,590 |
Table 12-3: Proven and Probable Mineral Reserve Statement (Copper)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Proven Mineral Reserves | Probable Mineral Reserves | Proven and Probable Mineral Reserves |
Tonnage (x 1,000 t) | Grade (Cu %) | Cont. Copper (M lbs) | Tonnage (x 1,000 t) | Grade (Cu %) | Cont. Copper (M lbs) | Tonnage (x 1,000 t) | Grade (Cu %) | Cont. Copper (M lbs) |
North Pit | 78,800 | 0.10 | 170 | 94,700 | 0.11 | 240 | 173,500 | 0.11 | 410 |
South Pit | 158,600 | 0.11 | 380 | 144,400 | 0.11 | 350 | 303,000 | 0.11 | 730 |
Open Pit Sub-Total | 237,400 | 0.10 | 550 | 239,100 | 0.11 | 590 | 476,500 | 0.11 | 1,140 |
Stockpile Sub-Total | 2,600 | 0.09 | 10 | 79,100 | 0.09 | 150 | 81,800 | 0.09 | 160 |
Boddington Total | 240,100 | 0.10 | 550 | 318,200 | 0.11 | 740 | 558,300 | 0.11 | 1,300 |
Notes to accompany mineral reserve tables:
1.Mineral reserves are current as at 31 December, 2021. Mineral reserves are reported using the definitions in SK1300 on a 100% basis. The Qualified Person responsible for the estimate is Mr. Donald Doe, RM SME, Group Executive, Reserves, a Newmont employee.
2.Mineral reserves are reported at the point of delivery to the process plant.
3.Mineral reserves that will be mined using open pit mining methods are constrained within a designed pit. Parameters used are included in Table 12-1.
4.Tonnages are metric tonnes rounded to the nearest 100,000. Gold grade is rounded to the nearest 0.01 gold grams per tonne. Copper grade is %. Gold ounces and copper pounds are estimates of metal contained in tonnages and do not include allowances for processing losses. Contained (cont.) gold ounces are reported as troy ounces, rounded to the nearest 10,000. Copper is reported as pounds. Rounding of tonnes and contained metal content as required by reporting guidelines may result in apparent differences between tonnes, grade and contained metal content. Due to rounding, some cells may show a zero (“0”).
5.Totals may not sum due to rounding.
| | | | | | | | |
Date: February, 2022 | | Page 12-4 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
12.8 Uncertainties (Factors) That May Affect the Mineral Reserve Estimate
Areas of uncertainty that may materially impact the mineral reserve estimates include:
•Changes to long-term metal price and exchange rate assumptions;
•Changes to metallurgical recovery assumptions;
•Changes to the input assumptions used to derive the pit designs applicable to the open pit mining methods used to constrain the estimates;
•Changes to the forecast dilution and mining recovery assumptions;
•Changes to the cut-off values applied to the estimates;
•Variations in geotechnical (including seismicity), hydrogeological and mining method assumptions;
•Changes to environmental, permitting and social license assumptions.
| | | | | | | | |
Date: February, 2022 | | Page 12-5 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
13.0 MINING METHODS
13.1 Introduction
Mineral reserves were estimated assuming open pit mining, and the use of conventional Owner-operated equipment.
13.2 Geotechnical Considerations
A number of geotechnical and hydrological studies were completed to support mining, feasibility, and environmental inputs. The geotechnical model for the Boddington deposit was defined by geotechnical drilling and logging, laboratory test work, rock mass classification, structural analysis, and stability modeling. The hydrological model was based on a three-dimensional flow model, historic pumping rates from the Jarrah Pit, and drill data.
The rock mass was characterized and grouped into geotechnical domains for design purposes using geotechnical and hydrogeological models as well as operational experience. A detailed structural model was constructed and maintained for input to both long term and operational design.
Ground support and rock fall mitigation measures used include:
•Cable bolting to reinforce unstable wedges and slabs;
•Wire-mesh for highly fractured/broken rock mass or poor scaling that creates significant amount of unstable and loose rock of the pit face;
•Rock fall fence or barrier that can be installed on a wide and stable catch berm or pit wall to capture rock fall from the benches above;
•Manual scaling by rope access to remove loose/unstable rock in areas where safe access is not available;
•Machine scaling and chaining of crests as part of the Batter Turn Over (BTO) process including using an excavator followed by a rock breaker to scale walls as part of routine work.
•A combination of the above methods.
Table 13-1 provides a brief summary of the geotechnical domains in operational pits and Table 13-2 provides the design configurations for all domains.
The minimum pit slope design acceptance criteria were specified in the Newmont Corporation – Surface Ground Control Standard - Open Pit (NEM-TES-STA-003, dated 31 May 2019). The acceptance criteria were adopted from Read and Stacey (2009) and are in line with mining industry standards.
Open pit designs were assessed and reviewed prior to pit excavation to ensure adequacy and integrity of design geometry with consideration to ground conditions. Three-dimensional models were developed for design geometry and various geological materials and structural features.
| | | | | | | | |
Date: February, 2022 | | Page 13-1 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Table 13-1: Geotechnical Domains
| | | | | |
Domain | Description |
Fresh andesite and diorite (all pits) | Andesite and diorite host rock which is exposed in most areas of all pits. There is no strong joint orientation. Joints are widely spaced (>1.0 m). Near-horizontal undulating fractures are reasonably common, and there are only few intermediate faults. Non-persistent moderate dipping (30º to 60º) closed joints are the main weakness planes that often open-up during blasting, which create incipient structures controlling crest damage |
Weathered andesite and diorite (all pits) | Andesite and diorite moderately to slightly weathered rock beneath the contact with oxide between the Saprolite and Fresh surfaces. This unit is clay altered with broken to highly fractured rocks. It has weaker joint conditions than the fresh material and is prone to increased crest loss when blasted and over time due to degradation. Increased ground support to maintain wall integrity and catch capacity is required in this domain |
Oxide/transition (all pits) | Poor rock-mass, soil strength, silty material. Completely to highly weathered material with relic structure |
Oxide/transition – S09 West Wall (S09 pit) | Poor rock-mass, soil strength, silty material. Completely to highly weathered material with relic structure. Batter angle laid back due to bench-scale slumping in previous cutback with no impact on overall slope angle |
Oxide/transition – S09 East Wall (S09 pit) | Poor rock-mass, soil strength, silty material. Completely to highly weathered with relic structure. This material has a higher degree of saturation compared to the western wall oxides. Relic structure is often dipping in to the pit |
Backfill (all pits) | Residual strength unspecified oxide materials from historic mining |
Vertical dolerites (all pits) | There are several late stage dolerite intrusion events which are similar from a geotechnical perspective. This is an extremely strong rock mass with UCS > 200 MPa. Moderately-spaced (0.3–1.0 m) planar joints are the main weakness causing this rock mass to be more sensitive to blasting (direction and set-up) and long-term degradation compared to the andesite and diorite in Domain 1 |
Sub-horizontal dolerite (South Pits) | Characterized by the existence of broken zones or layers associated with north-northeast dipping (15° to 30°) sub-horizontal dolerite sills that are exposed on the north and southeast walls of South Pits. The thicknesses of the broken zones vary from 0.3–8 m |
Western shear zone (North Pit) | Near vertical, moderately to well-developed foliation, shear zone of andesite and diorite, including a north–south-trending dolerite dyke. The shear within this wall is highly persistent, likely to below the final pit floor, with parallel structures. This domain requires extreme care when blasting, and is much more sensitive than the surrounding rock mass of Domain 1 |
A-breccia and South Bowl (North Pit) | Operational experience has shown that this area is challenging for wall control blast and excavation. Response to blasting and excavation suggested that rock mass is harder than in other areas. Slope performance is mostly unsatisfactory with poor crest retention. An above-average amount of scaling and a wider design catch berm are therefore required |
Sentinels wall (North Pit) | The Sentinel structural set is steeply dipping into the pit at 45–75º along the west wall of the N03 pit for the full height of the wall. Crest retention along these structures is poor and significant ground support is required. This domain requires extreme care during blasting |
| | | | | | | | |
Date: February, 2022 | | Page 13-2 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Table 13-2: Geotechnical Domain Design Configurations
| | | | | | | | | | | | | | | | | | | | | | | | | | |
Domain | Bench Height (m) | BFA 1st Flitch (˚) | BFA 2nd + 3rd Flitch (˚) | Batter Height (m) | IRA (˚) | Step-in berm (m) | Berm Width (m) | Berm Gradient (%) |
Fresh andesite and diorite | 12 | 75 | 90 | 36 | 60.8 | 1.3 | 15.2 | — |
Weathered andesite and diorite | 12 | 75 | 90 | 36 | 60.8 | 1.3 | 15.2 | — |
Oxide/transition | 12 | 54 | — | 12 | 30 | — | 12 | — |
Oxide/transition – S09 west wall | 12 | 45 | — | 12 | 30 | — | 9.0 | -3 (into pit) |
Oxide/transition – S09 east wall | 12 | 45 | — | 12 | 28 | — | 10.5 | -3 (into pit) |
Backfill | — | 20 | — | — | 20 | — | — | — |
Vertical dolerites | 12 | 75 | 90 | 36 | 58 | 1.3 | 17.3 | — |
Sub-horizontal dolerite broken zone | 12 | 65 | 90 | 36 | 56 | 1.3 | 17.0 | — |
Western shear zone | 12 | 75 | 90 | 36 | 59 | 1.3 | 16.7 | — |
A-Breccia and South Bowl | 12 | 75 | 90 | 36 | 59 | 1.3 | 16.7 | — |
Sentinels wall | 12 | 75 | 90 | 36 | 59 | 1.3 | 16.7 | — |
The models were used to assess slope stability. Slope stability models incorporated material parameters derived during ground investigations, laboratory testing and assessments of in-situ conditions as appropriate. Hydrogeological data from dedicated monitoring stations were also used to characterize geotechnical slope stability models.
Overall pit slope angles varied between approximately 37–52º according to geology and location of pit infrastructure such as ramps and haul roads. Inter-ramp slope angles in hard rock varied between 58–60.8º depending on specific conditions encountered within pit walls. The inter-ramp slope angles within oxide slopes varied between 20–30º.
A continuous system of assessment was implemented and adhered to during ongoing excavation processes in order to document and verify geological conditions as they were encountered. A structural model was maintained, updated and made available to help inform ongoing operations. Geotechnical staff were also employed to offer progressive assessments of conditions encountered during excavation including providing documented guidance to inform pit development initiatives. Automated deformation monitoring systems including alarmed slope stability radars and automated prism monitoring stations were also maintained and used to supplement performance assessment.
13.3 Hydrogeological Considerations
The pit dewatering system will continuously receive large volumes of groundwater and surface run-off over the LOM. The sum of active and passive dewatering was relatively constant at approximately 140 L/sec (4.4 GL/year), of which water carts consume about 0.5–0.8 GL/year. The long-term dewatering strategy assumes that this trend continues throughout the LOM.
| | | | | | | | |
Date: February, 2022 | | Page 13-3 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
The infrastructure requirement is 460 L/sec per pit (excluding satellite pits) when mining at the bottom of pit. The primary reason for the high designed maximum pumping rate is for mitigation pit flooding risks. The water management strategy is to maximize the use of the groundwater within the process plant and the loss of excess water by evaporation from the TSF. There is provision in place to capture excess surface water in water storage reservoirs.
The LOM pit dewatering plan will strategically upgrade the in-pit sump pump system (passive dewatering) and dewatering-bores (active dewatering) to cope with operational needs as required.
13.4 Operations
The LOM plan envisages mining at an average rate of approximately 80 Mt/a for 14 years, peaking at 93 Mt/a in 2035, with a maximum rate of advance by pit stage of seven benches per annum and an average of five benches (60 m) per year.
The mine life will extend to 2034 with material mined from the open pit. Milling will cease in 2035 after treatment of stockpiled ore.
The mine plan assumes eight pit phases remain. An illustration showing the final pit layout is provided in Figure 13-1.
Pit design assumptions include haul road widths for two-way travel of 38 m, maximum ramp grades of 10% and minimum pit-bottom widths of 75 m as a safety measure.
13.5 Blasting and Explosives
All drilling operations are performed by Newmont with Newmont-owned rigs that are maintained by Atlas Copco under a maintenance and repair contract (MARC). The drill rigs are configured in the down-the-hole (DTH) mode, and consist of seven Atlas Copco PV231, three Atlas Copco DML and five Atlas Copco D65 rigs.
Production drilling and blasting is done on 12 m benches with patterns and powder factors varying by material type and geological conditions. Production blasting uses Heavy ANFO blends which is loaded into both production and buffer holes; the stemming length varies according to rock type and other geologic conditions.
| | | | | | | | |
Date: February, 2022 | | Page 13-4 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Figure 13-1: Final Pit Layout Plan
Note: Figure prepared by Newmont, 2021. WDX = waste rock storage facility expansion.
| | | | | | | | |
Date: February, 2022 | | Page 13-5 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
13.6 Grade Control
Grade control is conducted using blast hole samples which are assayed for gold, copper and sulfur. Blast holes are mapped for dolerite contacts. These assay samples and dolerite maps are used to develop ore control models for each shot blasted. The shots are modeled using OK and constructed using Vulcan software. A revenue script run to determine the value of each block taking into account gold and copper grade and modifying factors such as mining costs and recovery. The ore control models are blocked out using revenue and Vulcan’s Grade Control Optimizer software. These blocks are subsequently translated using blast movement data prior to marking out the boundaries on the pit floor at which time the shot is released for mining.
Patterns include:
•Ore is 5.2 x 5.2 m pattern, using a 13.5 m hole, and one sample is taken per blast hole;
•Waste is 5.7 x 5.7 m pattern using a 13.5 m hole, and one sample is taken per blast hole;
13.7 Production Schedule
The LOM production plan is included in Table 13-3 and Table 13-4.
13.8 Equipment
LOM peak equipment requirements are provided in Table 13-5.
13.9 Personnel
The mining personnel total required for LOM operations is about 658.
| | | | | | | | |
Date: February, 2022 | | Page 13-6 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Table 13-3: Production Schedule (2022–2030)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Item | Units | Total | 2022 | 2023 | 2024 | 2025 | 2026 | 2027 | 2028 | 2029 | 2030 |
Material mined | M tonnes | 987 | 76 | 92 | 92 | 93 | 92 | 86 | 85 | 83 | 63 |
Ore processed | M tonnes | 558 | 41 | 42 | 42 | 42 | 42 | 42 | 42 | 42 | 42 |
Table 13-4: Production Schedule (2031–2035)
| | | | | | | | | | | | | | | | | | | | |
Item | Units | 2031 | 2032 | 2033 | 2034 | 2035 |
Material mined | M tonnes | 57 | 42 | 28 | 10 | 0 |
Ore processed | M tonnes | 42 | 42 | 42 | 42 | 13 |
| | | | | | | | |
Date: February, 2022 | | Page 13-7 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Table 13-5: Equipment Requirements
| | | | | | | | |
Purpose | Type | Peak Number |
Hauling | 793 conventional expit and re-handle | 4 |
793 AHS expit and re-handle | 36 |
A009-CAT 785C WC | 3 |
785D water cart | 2 |
Loading | A012-CAT 966H (WL930) | 1 |
A001-Bucyrus 495HD-SH01 | 2 |
A002-Bucyrus RH340-SH04 | 2 |
A002-EX3600 | 1 |
Ancillary Loading Units | 6 |
A008- CAT 994H_Wheel Loaders | 2 |
Support | A006-CAT Track Dozers | 6 |
A006-CAT Wheel Dozers | 5 |
A007-CAT Graders | 4 |
A011-CAT330 | 2 |
Road sheeting roller | 2 |
785C Float | 1 |
A012-CAT 966H (WL13) | 2 |
Drilling | DML production drill | 6 |
PV235 production drill | 10 |
Drill water cart WC07 | 1 |
D65 presplit drill | 6 |
| | | | | | | | |
Date: February, 2022 | | Page 13-8 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
14.0 RECOVERY METHODS
14.1 Process Method Selection
The process plant design was based on a combination of metallurgical testwork, previous study designs, previous operating experience. The design is conventional to the gold industry and has no novel parameters.
14.2 Process Plant
A summary process flow sheet is included in Figure 14-1.
14.2.1 Plant Design
The selected process consists of primary crushing, closed circuit secondary and HPGR tertiary crushing, ball milling, and hydrocyclone classification to generate a milled product with a P80 of 150 μm at a slurry density of 35–38% solids.
Flash flotation facilities were included to treat a portion of the mill discharge stream; however, flash flotation trials were unsuccessful and the facilities were removed from the process flowsheet.
Cyclone overflow from the mill circuit is treated in a flotation circuit that produces a copper–gold concentrate for export. Rougher and scavenger flotation concentrates are reground and cleaned to achieve an acceptable final concentrate grade. Concentrate is thickened and filtered before being trucked to the port of Bunbury.
The cleaner–scavenger tailings stream is thickened and leached under elevated cyanide levels. Scavenger tailings are thickened and leached in a conventional leach/adsorption circuit. Leached slurry from the cleaner scavenger tailings leach circuit is delivered to the scavenger tailings circuit for combined recovery of gold.
Leach residue is pumped to the residue disposal area, and residual weakly acid-dissociable cyanide (CNwad) is maintained below a targeted level by a Caro’s acid cyanide destruction plant. This facility can treat the following streams:
•Decant water returning to the plant so that cyanide levels do not inhibit flotation;
•Decant water recycling to the decant pond to maintain CNwad levels in the pond at an average of 30 ppm and a not-to-exceed level of 50 ppm;
•Residue slurry from the plant to protect the decant pond from excursions caused by short-term variability in the copper head grade.
| | | | | | | | |
Date: February, 2022 | | Page 14-1 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Figure 14-1: Process Flowsheet
Figure prepared by Newmont, 2021.
The carbon from the scavenger tailings adsorption circuit is treated by a conventional split-Anglo American Research Laboratory (AARL) method elution and reactivated in horizontal reactivation kilns. Gold recovery from the eluate is by electrowinning, cathode sludge filtration and drying, and smelting.
Plant utilization in the LOM plan is 88.9% for the secondary/tertiary crushing circuits, and 88.9% for the milling circuit.
14.2.2 Equipment Sizing
The Project process plant incorporates the following major equipment:
•2.3 km overland conveyor;
•Two ROM stockpiles, two medium-grade stockpiles, three WRSF areas;
•Two 60-110 primary crushers;
•Six MP1000 secondary crushers;
•Four 3.6 m x 8.5 m coarse screens;
•Four 5.6 MW HPGR capacity (8,000 t/h);
•Four 15 MW ball mills (7.9 m x 13.4 m);
•Four flash flotation SK1800 Outotec cells: (decommissioned);
•Roughers/scavengers: three parallel trains consisting of 2 x 150 m3 and 6 x 200 m3 Outotec tank cells; | | | | | | | | |
Date: February, 2022 | | Page 14-2 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
•One 19 m diameter Outotec regrind high-rate thickener;
•Regrind mills: two Vtm 1250 950 kW Vertimills;
•First cleaners/cleaner scavengers: nine 100 m3 Outotec tank cells;
•Coarse cleaners: three 30 m3 Outotec tank cells;
•Second and third cleaners: five 8 m3 Outotec U-shape cells;
•One 27 m diameter Outotec high-rate concentrate thickener;
•One 108 m2 area Larox concentrate pressure filter;
•One 19 m diameter Outotec cleaner scavenger tails high- rate thickener;
•One 74 m diameter Outotec scavenger tails high-rate thickener;
•Two 450 m3 and seven 175 m3 cleaner scavenger tails (CSt) leach tanks;
•Carbon-in-leach: two parallel trains (each 12 leach tanks); total 60,500 m3 capacity.
14.3 Power and Consumables
Power supply to the operations is via the local grid system with a coal-fired power station built at Collie providing the additional demand for the operation as well as supplementing the existing grid.
Water supply is from a number of sources, including the Hotham river (during winter only), pit dewatering water, borefield water adjacent to the pits, rainfall run-off and recovered water from the thickeners and TSF. Decreased rainfall during winter could impact the mill production if sufficient water cannot be drawn from the river.
Consumables used in the processing include grinding media, primary collector (thionocarbamate), secondary collector (xanthate), frother, lime, flocculant, cyanide, oxygen, caustic, sulfuric and hydrochloric acid, and peroxide.
14.4 Personnel
The process plant has a personnel count of 423.
| | | | | | | | |
Date: February, 2022 | | Page 14-3 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
15.0 INFRASTRUCTURE
15.1 Introduction
The majority of the key infrastructure required to support mining operations is constructed and operational. This includes:
•Open pit;
•Roads;
•Two ROM stockpiles, one medium-grade stockpile, two WRSFs;
•TSFs;
•2.3 km overland conveyor;
•Four major water management facilities, including a decant water pond and water recycling facility;
•Electrical sub-station;
•Concentrate storage shed and load-out facility;
•Accommodation village;
•Heavy equipment and light vehicle shops, warehouses, and offices;
•On-site core storage, and sample pulp storage.
A layout plan is included as Figure 15-1.
A second TSF is required for the LOM plan.
15.2 Roads and Logistics
The Project is accessed by an all-weather road network from Perth as discussed in Chapter 4.
15.3 Waste Rock Storage Facilities
A number of WRSFs are in use, segregated as oxide or rock facilities. Potentially acid-forming waste is encapsulated as required. A WRSF expansion in the 10WD area was completed in 2021 to provide capacity until mid-year 2024. In 2022–2023, areas to the west of the D4 Dam and 11WD will be cleared to provide sufficient capacity for operational requirements for the remaining LOM.
| | | | | | | | |
Date: February, 2022 | | Page 15-1 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Figure 15-1: Infrastructure Layout Plan
Note: Figure prepared by Newmont, 2019. RDA = residue disposal area (TSF).
| | | | | | | | |
Date: February, 2022 | | Page 15-2 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
15.4 Stockpiles
Boddington operates two run-of-mine (ROM) stockpiles; ROM and ROM premium (ROMPR) located adjacent to the crusher on the west side of the North Pit. The cut-offs for ROM stockpiles are adjusted quarterly to ensure the preferential feed for the period. The ROMPR cut-off is AU$28/t and ROM varies between is AU$17.06–AU$21.75/t.
Newmont operates a medium-grade stockpile, MG2, which is located to the northwest of the South Pit. Entry to the MG2 stockpile is tested using the stockpile (mineral reserve) cut-off AU$17.06/t.
Stockpiling of ROMPR and ROM cut-off grade ores will be for short periods of time with no recovery degradation effect expected. Stockpiling of MG2 material will allow the material to oxidize for several years prior to processing. Benchmarking of sites with similar mineralogy and climatic conditions led to a baseline assumption that processing of these oxidized stockpile ores will result in a 6% loss in copper recovery and a 3% loss in gold recovery when they are finally processed.
A program for testing the oxidation rates and impact to recovery was developed with Newmont Metallurgical Services and was ongoing since November 2016. A review of the testwork completed to date has recommended that the Boddington Operations continue to apply a 6% deduction to the modelled copper recovery and 3% deduction to the modelled gold recovery to both medium-term stockpiling of high-grade ore and long-term stockpiling of medium-grade ore (Petrucci, 2021).
The combined stockpile is located adjacent to the crusher on the west side of the North Pit And reaches peak capacity in 2027 with 137 Mt.
The stockpiles are reclaimed using a preferential high-grade feed strategy, with the lower medium-grade stockpiles being re-handled to the mill towards the end of the LOM. The stockpiles are reclaimed using conventional mining fleet and loading units.
15.5 Tailings Storage Facilities
The F1/F3 residue disposal area (RDA) is the current active TSF for the Boddington Operations.
The current F1/F3 dam has approved capacity to 600 Mt, which will provide sufficient storage for tailings storage to 2025, assuming remaining capacity of 163 Mt, and an approximate 42 Mt/a process rate. The approved facility has 11 perimeter embankments, of which all are in place.
Newmont plans to expand the facility to 750 Mt, which, assuming the same approximately 42 Mt/a process rate, will provide tailings capacity to 2029. The expansion to 750 Mt is not currently permitted.
Additional storage that will be required for the LOM beyond 2029 is being evaluated by Newmont. This is currently envisaged as a new RDA with a 250 Mt capacity. Newmont has established a pathway and a timeline for the RDA approval and construction such that storage capacity will be available when needed.
The key input parameters dictating the RDA construction quantities and schedule include:
•Process plant throughput;
| | | | | | | | |
Date: February, 2022 | | Page 15-3 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
•Annual rate of rise from tailings deposition;
•Beach slope angles;
•Capacity for dam expansion;
•Management of scope within the available construction areas;
•Embankment designs and infrastructure to ensure geotechnical factors of safety in line with the Australian National Committee on Large Dams (2019) guidelines.
The TSF is operated as a zero-discharge facility; all water is returned to the process facility for reuse.
The TSF has enhanced monitoring systems including an extensive network of piezometers and inclinometers to track dam performance against the Trigger Action Response Plan, and to support proactive dam safety management.
15.6 Water Management Structures
Water management infrastructure for mine operations include the following:
•Pit dewatering infrastructure for pumping away both surface run-off and groundwater from open pits and for monitoring pore pressure distribution, which consists of:
◦In-pit sump pumping (passive dewatering);
◦Dewatering-bores (active dewatering);
◦Grouted multiple vibrating wire piezometer pore pressure monitoring bores;
•Mine surface water drainage infrastructure for mitigating risks associated with storm water, sediments, erosions, saturations of ground and ARD (Acid Rock Drainage),in accordance with the water characterization, which consists of:
◦Fresh water (non-contact water);
◦Mine water (contact water – no ARD);
◦Impacted water (contact water – potential ARD).
Where practicable, the drainage infrastructures in the mining area are designed and constructed to segregate each characterized water from others by means of designated open channel network, sub-surface drainage systems, water retaining ponds and water reticulation infrastructures. All surface runoff and waste dump seepage are collected at designated retention ponds and pumped-away to the plant. As required, the drainage system has an ability of discharging a portion of fresh water to the downstream as an environmental flow.
15.7 Water Supply
Process water is supplied direct from the mine pits, from onsite storage reservoirs which were filled in the winter months by pumping from the Hotham River under a license from the Department of Water or from regional water bores which are available all year round. Process water is also sourced as reclamation of water from the decant pond at the TSF.
| | | | | | | | |
Date: February, 2022 | | Page 15-4 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Potable water for the camp and mining operation is sourced from two 550 kL water storage tanks.
The site-wide water balance is managed through a GoldSim model, with regular water use, abstraction and storage capacity data regularly fed into the model to obtain reliable forecasts of process and raw water.
15.8 Camps and Accommodation
The current workforce consists of approximately 1,000 employees and 700 contractors with approximately 25% of these residing locally within a 25 km radius of the operations and the balance residing in a purpose-built accommodation village.
15.9 Power and Electrical
Power is sourced from the Bluewater Power Station, a coal-fired power station located 4.5 km northeast of Collie, and approximately 80 km from the mine. Power is transmitted through the State power grid from the power station to the mine site.
| | | | | | | | |
Date: February, 2022 | | Page 15-5 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
16.0 MARKET STUDIES AND CONTRACTS
16.1 Markets
Newmont has established contracts and buyers for copper concentrate and doré products, and has an internal marketing group that monitors markets for its concentrate and doré products. Together with public documents and analyst forecasts, there is a reasonable basis to assume that for the LOM plan, the copper concentrate and doré will be saleable.
The concentrate produced is marketed as a gold–copper concentrate. Smelters operating their own precious metal refineries at their copper smelting operations are best suited to contract for Boddington concentrates. Long-term contracts are in place with smelters in Korea, Japan, Philippines, and Germany for a large portion of the mine production of copper concentrate. The remaining production is placed on the spot market. The pricing of the concentrate is driven by London Metal Exchange copper pricing, LBMA gold pricing, and annual processing benchmark terms negotiated by major industry players and published by third-party data providers.
Doré is sold on the spot market by in-house marketing experts.
There are no agency relationships relevant to the marketing strategies used.
Product valuation is included in the economic analysis in Chapter 19, and is based on a combination of the metallurgical recovery, commodity pricing, and consideration of processing charges.
16.2 Commodity Price Forecasts
Newmont uses a combination of historical and current contract pricing, contract negotiations, knowledge of its key markets from a long operations production record, short-term versus long-term price forecasts prepared by Newmont’s internal corporate marketing group, public documents, and analyst forecasts when considering long-term commodity price forecasts.
Higher metal prices are used for the mineral resource estimates to ensure the mineral reserves are a sub-set of, and not constrained by, the mineral resources, in accordance with industry-accepted practice.
The long-term commodity price and exchange rate forecasts are:
Mineral reserves:
•Gold: US$1,200/oz;
•Copper: US$2.75/lb;
•US$:AU$: 0.75.
Mineral resources:
•Gold: US$1,400/oz;
•Copper: US$3.25/lb;
•US$:AU$: 0.75.
| | | | | | | | |
Date: February, 2022 | | Page 16-1 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
16.3 Contracts
Newmont has contracts in place for the majority of the copper concentrate. The terms contained within the concentrate sales contracts are typical and consistent with standard industry practice for high-gold, low-copper concentrates.
The contracts include industry benchmark terms for metal payables, treatment charges and refining charges for concentrates produced. Depending on the specific contract, the terms for the sale of the copper concentrate are either annually negotiated, benchmark-based treatment and refining charges, or a combination of annually-negotiated terms.
Treatment charges assumed for estimation of mineral reserves are based on the forecasts published by third-party data providers such as Wood Mackenzie or CRU. The formula used for mineral reserves is sensitive to the underlying copper price and is consistent with long-term expectations for copper treatment and refining charges.
Newmont’s doré is sold on the spot market, by marketing experts retained in-house by Newmont. The terms contained within the sales contracts are typical and consistent with standard industry practice and are similar to contracts for the supply of doré elsewhere in the world.
The largest in-place contracts other than for product sales cover items such as bulk commodities, operational and technical services, mining and process equipment, and administrative support services. Contracts are negotiated and renewed as needed. Contract terms are typical of similar contracts in Australia that Newmont is familiar with.
| | | | | | | | |
Date: February, 2022 | | Page 16-2 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
17.0 ENVIRONMENTAL STUDIES, PERMITTING, AND PLANS, NEGOTIATIONS, OR AGREEMENTS WITH LOCAL INDIVIDUALS OR GROUPS
17.1 Introduction
Two phases of gold mining were conducted, from 1987–2001, and from 2009 to date.
17.2 Baseline and Supporting Studies
Baseline and supporting environmental studies were completed to assess both pre-existing and ongoing site environmental conditions, as well as to support decision-making processes during operations start-up and restart. Characterization studies were completed for all environmental media including soil, water, waste, air, noise and closure.
Plans were developed and implemented to address aspects of operations such as waste and fugitive dust management, spill prevention and contingency planning, water management, and noise levels.
17.3 Environmental Considerations/Monitoring Programs
Monitoring and regulatory compliance systems were updated following approval of the current operations in 2015 based on a 2036 LOM footprint. Areas that are monitored include waste rock, TSF, water, air quality, and noise.
There are five species classified as Threatened Species/Matters of National Environmental Significance in the Project area, including three species of black cockatoo (Baudin’s, Carnaby’s and Forest Red-Tailed), and two species of marsupial, woylie and chuditch. All five species have site-specific management plans.
17.4 Closure and Reclamation Considerations
17.4.1 Closure Plans
The 1978 WA Mining Act requires that Newmont submits a closure plan every three years that is compliant with the Guidelines for Preparing Mine Closure Plans (Department of Mines and Petroleum & Environmental Protection Authority, 2015).
The most recent closure plan was submitted in 2019. The closure plan covers rehabilitation of the WRSFs, TSF, processing plant and other areas of disturbance. The open pits will be allowed to develop into pit lakes. The closure strategy for disturbance associated with infrastructure and services is to re-shape disturbance areas to blend in with the surrounding topography and revegetate with local species.
| | | | | | | | |
Date: February, 2022 | | Page 17-1 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
17.4.2 Closure Costs
The Annual Environmental Report provided to the applicable regulatory agencies of the West Australian government must be accompanied by the disturbance (cleared) area for the mining operations. The disturbance area is used to calculate the annual 1% liability levy under the Mine Rehabilitation Fund that is charged to the site and remains in effect until all tenements were signed off as rehabilitated. In 2021, the levy amounted to approximately AU$1,403 M. Due to the bauxite State Agreements, there is one tenement for which the Mine Rehabilitation Fund does not apply, and a bond, to the value of AU$3.63 M, was lodged.
Newmont also calculates the closure costs for the Boddington Operations as part of internal closure and financial planning. The closure estimate, as at 2021, assuming operations to 2035, is calculated as approximately AU$0.5 B.
17.5 Permitting
All major permits and approvals are either in place or Newmont expects to obtain them in the normal course of business. Additional permitting will be required to support the tailings disposal required in the LOM plan.
Where permits have specific terms, renewal applications are made of the relevant regulatory authority as required, prior to the end of the permit term.
Newmont monitors the regulatory regime in place at each of its operations and ensures that all permits are updated in line with any regulatory changes.
17.6 Social Considerations, Plans, Negotiations and Agreements
The Boddington Operations are located within the Shire of Boddington local government area. Newmont defines the host communities for the Boddington Operations as those within a 50 km radius of the operation. These include the local government areas of Boddington, Williams, and Wandering, and the community of Dwellingup. The Project’s area of influence consists of the following hierarchy that is applied to engagement, employment, procurement and discretionary social investment:
•The local government areas and communities;
•The Gnaala Karla Booja Native Title Claimant or Indigenous Land Use Agreement area including the regional centers of Kwinana, Armadale, Rockingham, Bunbury, Collie, Narrogin, and Mandurah;
•The broader southwest WA region including the greater Perth metropolitan area.
In 2019 and 2020, the Boddington Operations completed the most recent five-yearly Social Impact Assessment and Social Baseline and Economic Contribution Assessment updates, which were supported by perception survey engagement processes. These social knowledge base studies quantify the operations social license, impact, engagement, employment, procurement and discretionary investment aspects and inform LOM Social Management Planning.
Newmont has well-established relationships, engagement forums, and a suite of integrated social impact and opportunity-aligned strategic investment partnerships.
| | | | | | | | |
Date: February, 2022 | | Page 17-2 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
The operations area is subject to the South West Native Title Settlement. The Preservation of Aboriginal Heritage Agreement formalized in 2007 prescribes the operations Heritage Area of Influence, the Heritage Agreement Project Area and Newmont’s particular heritage responsibilities reflected in the operations Cultural Heritage Management Plan. The Preservation of Aboriginal Heritage Agreement underpins and frames the heritage aspects of the Moorditj Booja Community Partnership Agreement (2006) between Gnaala Karla Booja People, Newmont, and the South West Aboriginal Land and Sea Council. The Preservation of Aboriginal Heritage Agreement ensures that Newmont meets and exceeds the minimum obligations prescribed in the State’s Aboriginal Heritage Act 1972.
The agreement sets out processes for:
•Communication and consultation via the Relationship Committee;
•Joint management of Aboriginal heritage;
•Heritage survey request triggers, methods and team selection procedures;
•Heritage survey costs and reporting;
•Monitoring of ground disturbance works at specified Aboriginal sites;
•Breaches and grievance resolution;
•Environmental protection;
•Identification and relocation of ancestral remains or objects;
•Section 18 Ministerial Consent processes;
•Identification, protection and preservation of Aboriginal cultural heritage;
•Preservation of Aboriginal sites and objects.
Aboriginal heritage sites identified in surveys are registered with the Aboriginal Heritage Inquiry System managed by the WA Department of Planning, Lands and Heritage. Sites are also mapped into Newmont’s ARC GIS heritage layers, are reflected in the site’s Cultural Heritage Management Plan and inform the operation’s Aboriginal cultural heritage due diligence that is embedded in Newmont’s Disturbance Permitting Processes.
17.7 Qualified Person’s Opinion on Adequacy of Current Plans to Address Issues
Based on the information provided to the QP by Newmont (see Chapter 25), there are no material issues known to the QP. The Boddington Operations are mature mining operations and currently has the social license to operate within its local communities.
| | | | | | | | |
Date: February, 2022 | | Page 17-3 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
18.0 CAPITAL AND OPERATING COSTS
18.1 Introduction
Capital and operating cost estimates are at a minimum at a pre-feasibility level of confidence, having an accuracy level of ±25% and a contingency range not exceeding 15%.
18.2 Capital Cost Estimates
18.2.1 Basis of Estimate
Capital costs are based on recent prices or operating data. Capital costs include funding for infrastructure, pit dewatering, development drilling, and permitting as well as miscellaneous expenditures required to maintain production. Mobile equipment re-build/replacement schedules and fixed asset replacement and refurbishment schedules are included. Sustaining capital costs reflect current price trends.
Newmont applies a time value of money in the development of sustaining capital costs per unit of mass mined. Equipment capital costs can be recovered by using an amortization rate per unit of mass mined so that the net present value of the future cash flow generated from this charge is equal to the equipment capital cost. The capital recovery factor (CRF) is required to give a 5% pre-tax return on an investment over the life of fleet or facility. The CRF for mining and processing is estimated at 110% and 112% respectively. Including the CRF, the mining sustaining capital is AU$0.83/t mined at CRF 1.10, and processing and general and administrative (G&A) sustaining capital is AU$1.95/t milled at CRF 1.12.
18.2.2 Capital Cost Estimate Summary
The overall capital cost estimate for the LOM is AU$1.8 B, as summarized in Table 18-1.
18.3 Operating Cost Estimates
18.3.1 Basis of Estimate
Operating costs are based on actual costs seen during operations and are projected through the LOM plan. Historical costs are used as the basis for operating cost forecasts for supplies and services unless there are new contract terms for these items. Labor and energy costs are based on budgeted rates applied to headcounts and energy consumption estimates.
Table 18-1: Capital Cost Estimate
| | | | | | | | | | | |
Area | Unit | Value | |
Mining | AU$ B | 0.7 | |
Process | AU$ B | 1.1 | |
Site G&A | AU$ B | 0 | * |
Total | AU$ B | 1.8 | |
| | | | | | | | |
Date: February, 2022 | | Page 18-1 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Note: numbers have been rounded; totals may not sum due to rounding. * The zero in the table represents numeric data that do not display due to the rounding.
18.3.2 Operating Cost Estimate Summary
Operating costs for the LOM are estimated at AU$11.7 B, as summarized in Table 18-2. The estimated LOM mining cost is AU$4.31/t. Base processing costs are estimated at AU$11.11/t. In addition, G&A costs are estimated at AU$2.25/t.
Table 18-2: Operating Cost Estimate
| | | | | | | | |
Area | Unit | Value |
Mining | AU$ B | 4.2 |
Process | AU$ B | 6.2 |
G&A | AU$ B | 1.3 |
Total | AU$ B | 11.7 |
Note: numbers have been rounded; totals may not sum due to rounding.
| | | | | | | | |
Date: February, 2022 | | Page 18-2 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
19.0 ECONOMIC ANALYSIS
19.1 Methodology Used
The financial model that supports the mineral reserve declaration is a standalone model that calculates annual cash flows based on scheduled ore production, assumed processing recoveries, metal sale prices and AU$/US$ exchange rate, projected operating and capital costs and estimated taxes.
The financial analysis is based on an after-tax discount rate of 5%. All costs and prices are in unescalated “real” dollars. The currency used to document the cash flow is US$.
All costs are based on the 2022 business plan budget. Revenue is calculated from the recoverable metals and long-term metal price and exchange rate forecasts.
19.2 Financial Model Parameters
The economic analysis is based on the metallurgical recovery predictions in Chapter 10.4, the mineral reserve estimates in Chapter 13, the mine plan discussed in Chapter 14, the commodity price forecasts in Chapter 16, closure cost estimates in Chapter 17.4, and the capital and operating costs outlined in Chapter 18. Royalties were summarized in Chapter 3.9.
The Boddington Operations are subject to a federal tax rate of 30% on taxable income.
The economic analysis is based on 100% equity financing and is reported on a 100% project ownership basis. The economic analysis assumes constant prices with no inflationary adjustments.
The NPV5% is US$2.1 B. As the cashflows are based on existing operations where all costs are considered sunk to 1 January 2022, considerations of payback and internal rate of return are not relevant.
A summary of the financial results is provided in Table 19-1. An annualized cashflow statement is provided in Table 19-2 and Table 19-3. In these tables, EBITDA = earnings before interest, taxes, depreciation and amortization. The active mining operation ceases in 2034, and processing ceases in 2035; however, closure costs are estimated to 2055. Closure costs in the period 2034–2055 total 0.2 B.
19.3 Sensitivity Analysis
The sensitivity of the Project to changes in metal prices, exchange rate, sustaining capital costs and operating cost assumptions was tested using a range of 25% above and below the base case values (Figure 19-1).
The Project is most sensitive to metal price changes, less sensitive to changes in operating costs, and least sensitive to changes in capital costs.
The sensitivity to grade mirrors the sensitivity to the gold price and is not shown.
| | | | | | | | |
Date: February, 2022 | | Page 19-1 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Table 19-1: Cashflow Summary Table
| | | | | | | | |
Item | Unit | Value |
Metal prices |
Gold | US$/oz | 1,200 |
Copper | US$/lb | 2.75 |
Mined Ore |
Tonnage | M tonnes | 558 |
Gold grade | g/t | 0.65 |
Copper grade | % | 0.11% |
Gold ounces | Moz | 11.6 |
Copper pounds | Blb | 1.3 |
Capital costs | US$B | 1.3 |
Costs applicable to sales | US$B | 9.7 |
Discount rate | % | 5 |
Exchange rate | Australian dollar:United States dollar (AUD:USD) | 0.75 |
Free cash flow | US$B | 2.7 |
Net present value | US$B | 2.1 |
Note: Numbers have been rounded; totals may not sum due to rounding. Table 19-1 contains “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, which are intended to be covered by the safe harbor created by such sections and other applicable laws. Please refer to the note regarding forward-looking information at the front of the Report. The cash flow is only intended to demonstrate the financial viability of the Project. Investors are cautioned that the above is based upon certain assumptions which may differ from Newmont’s long-term outlook or actual financial results, including, but not limited to commodity prices, escalation assumptions and other technical inputs. For example, Table 19-1 uses the price assumptions stated in the table, including a gold commodity price assumption of US$1,200/oz, which varies significantly from current gold prices and the assumptions that Newmont uses for its long-term guidance. Please be reminded that significant variation of metal prices, costs and other key assumptions may require modifications to mine plans, models, and prospects.
| | | | | | | | |
Date: February, 2022 | | Page 19-2 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Table 19-2: Annualized Cashflow (2022–2029)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Item | Units | LOM Total | 2022 | 2023 | 2024 | 2025 | 2026 | 2027 | 2028 | 2029 |
Material mined | M tonnes | 987 | 76 | 92 | 92 | 93 | 92 | 86 | 85 | 83 |
Ore processed | M tonnes | 558 | 41 | 42 | 42 | 42 | 42 | 42 | 42 | 42 |
Contained gold, processed | Moz | 11.6 | 1.1 | 1.0 | 1.0 | 1.0 | 1.0 | 0.9 | 0.9 | 0.8 |
Contained copper, processed | Mlbs | 1,296 | 136 | 138 | 114 | 86 | 85 | 87 | 86 | 85 |
Processed ore gold grade | g/t | 0.65 | 0.83 | 0.76 | 0.75 | 0.74 | 0.75 | 0.67 | 0.66 | 0.61 |
Processed ore copper grade | % | 0.11 | 0.15 | 0.15 | 0.12 | 0.09 | 0.09 | 0.09 | 0.09 | 0.09 |
Recovered gold | Moz | 9.9 | 1.0 | 0.9 | 0.9 | 0.9 | 0.9 | 0.8 | 0.8 | 0.7 |
Recovered copper | Mlbs | 1,057 | 114 | 116 | 95 | 70 | 68 | 71 | 70 | 70 |
Recovery, gold | % | 85 | 88 | 87 | 87 | 86 | 87 | 86 | 86 | 85 |
Recovery, copper | % | 82 | 84 | 84 | 83 | 82 | 81 | 81 | 82 | 82 |
Net revenue | US$ billion | 14.1 | 1.4 | 1.3 | 1.3 | 1.2 | 1.2 | 1.1 | 1.1 | 1.0 |
Costs applicable to sales | US$ billion | -9.7 | -0.8 | -0.8 | -0.7 | -0.7 | -0.7 | -0.7 | -0.8 | -0.8 |
Other expenses | US$ billion | -0.1 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
EBITDA | US$ billion | 4.2 | 0.6 | 0.5 | 0.5 | 0.4 | 0.5 | 0.4 | 0.3 | 0.2 |
Operating cash flow (after estimated taxes and other adjustments) | US$ billion | 4.0 | 0.5 | 0.4 | 0.4 | 0.4 | 0.3 | 0.3 | 0.3 | 0.3 |
Total capital | US$ billion | -1.3 | -0.1 | -0.1 | -0.1 | -0.1 | -0.1 | -0.2 | -0.1 | -0.1 |
Free cash flow | US$ billion | 2.7 | 0.4 | 0.3 | 0.3 | 0.3 | 0.2 | 0.1 | 0.1 | 0.1 |
| | | | | | | | |
Date: February, 2022 | | Page 19-3 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Table 19-3: Annualized Cashflow (2030–2036)
| | | | | | | | | | | | | | | | | | | | | | | | | | |
Item | Units | 2030 | 2031 | 2032 | 2033 | 2034 | 2035 | 2036 |
Material mined | M tonnes | 63 | 57 | 42 | 28 | 10 | 0 | 0 |
Ore processed | M tonnes | 42 | 42 | 42 | 42 | 42 | 13 | 0 |
Contained gold, processed | Moz | 0.8 | 0.7 | 0.7 | 0.8 | 0.7 | 0.2 | 0.0 |
Contained copper, processed | Mlbs | 71 | 92 | 99 | 107 | 86 | 24 | 0 |
Processed ore gold grade | g/t | 0.59 | 0.53 | 0.53 | 0.56 | 0.49 | 0.42 | — |
Processed ore copper grade | % | 0.08 | 0.10 | 0.11 | 0.12 | 0.09 | 0.08 | 0.00 |
Recovered gold | Moz | 0.7 | 0.6 | 0.6 | 0.6 | 0.5 | 0.1 | 0.0 |
Recovered copper | Mlbs | 56 | 74 | 80 | 87 | 68 | 19 | 0 |
Recovery, gold | % | 84 | 83 | 83 | 84 | 81 | 79 | 0 |
Recovery, copper | % | 79 | 80 | 81 | 81 | 79 | 77 | 0 |
Net revenue | US$ billion | 0.9 | 0.9 | 0.9 | 0.9 | 0.8 | 0.2 | 0.0 |
Costs applicable to sales | US$ billion | -0.7 | -0.7 | -0.8 | -0.8 | -0.5 | -0.2 | 0.0 |
Other expenses | US$ billion | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
EBITDA | US$ billion | 0.2 | 0.1 | 0.1 | 0.1 | 0.3 | 0.1 | 0.0 |
Operating cash flow (after estimated taxes and other adjustments) | US$ billion | 0.3 | 0.2 | 0.2 | 0.3 | 0.3 | 0.1 | 0.0 |
Total capital | US$ billion | -0.1 | -0.1 | -0.1 | 0.0 | 0.0 | 0.0 | 0.0 |
Free cash flow | US$ billion | 0.1 | 0.1 | 0.1 | 0.2 | 0.2 | 0.1 | 0.0 |
Note: Numbers have been rounded; totals may not sum due to rounding. EBITDA = earnings before interest, taxes, depreciation and amortization. Table 19-2 and Table 19-3 contain “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, which are intended to be covered by the safe harbor created by such sections and other applicable laws. Please refer to the note regarding forward-looking information at the front of the Report. The cash flow is only intended to demonstrate the financial viability of the Project. Investors are cautioned that the above is based upon certain assumptions which may differ from Newmont’s long-term outlook or actual financial results, including, but not limited to commodity prices, escalation assumptions and other technical inputs. For example, Table 19-2 use the price assumptions stated in the table, including a gold commodity price assumption of US$1,200/oz, which varies significantly from current gold prices and the assumptions that Newmont uses for its long-term guidance. Please be reminded that significant variation of metal prices, costs and other key assumptions may require modifications to mine plans, models, and prospects.
| | | | | | | | |
Date: February, 2022 | | Page 19-4 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Figure 19-1: NPV Sensitivity
Note: Figure prepared by Newmont, 2021. FCF = free cashflow; op cost = operating cost; cap cost = capital cost; NPV = net present value.
| | | | | | | | |
Date: February, 2022 | | Page 19-5 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
20.0 ADJACENT PROPERTIES
This Chapter is not relevant to this Report.
| | | | | | | | |
Date: February, 2022 | | Page 20-1 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
21.0 OTHER RELEVANT DATA AND INFORMATION
This Chapter is not relevant to this Report.
| | | | | | | | |
Date: February, 2022 | | Page 21-1 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
22.0 INTERPRETATION AND CONCLUSIONS
22.1 Introduction
The QP notes the following interpretations and conclusions, based on the review of data available for this Report.
22.2 Property Setting
The Boddington Operations are located in an area that has more than 40 years of mining activity. As a result, local and regional infrastructure and the supply of goods available to support mining operations is well-established. Personnel with experience in mining-related activities are available in the district. There are excellent transportation routes that access the Boddington area.
There are no significant topographic or physiographic issues that would affect the Boddington Operations. The dominant vegetation type is temperate boreal forest.
Mining operations are conducted year-round.
22.3 Ownership
The current parties to the BGMJV are Newmont Boddington Pty Ltd (66⅔%) and Saddleback Investments Pty Ltd (Saddleback; (33⅓%). Both companies are indirectly-wholly owned Newmont subsidiaries.
22.4 Mineral Tenure, Surface Rights, Water Rights, Royalties and Agreements
Newmont subleases from the Worsley JV the key mining leases upon which the Boddington operations are located, namely M70/21–26, M70/564 and M70/799. Newmont is entitled to all gold and other non-bauxite mining rights conferred by the lease. The Worsley JV retains the rights to bauxite and priority rights of access in order to mine and recover such bauxite.
The relationship between the Worsley JV bauxite operations and the BGMJV gold operations is regulated through a cross-operation agreement. This agreement confers priority on the bauxite operations such that the operations of the Worsley JV will take priority over the operations of the BGMJV and the BGMJV are required to take reasonable measures to conserve bauxite including by mining and stockpiling bauxite on behalf of the Worsley JV.
Newmont has an interest in a total of 89 tenements in the Boddington area The total granted area is approximately 21,249 ha and the under-application area is approximately 60,767 ha.
Mining leases M70/21–26 and M70/799 are the key tenements under which gold mining activity is concentrated.
Through direct lease holding and sub-lease arrangements with the Worsley JV, Newmont holds the rights to minerals other than bauxite in proportion to the Newmont ownership percentages.
Newmont holds sufficient surface rights to execute the LOM plan.
| | | | | | | | |
Date: February, 2022 | | Page 22-1 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Process water is supplied direct from the mine pits, from onsite storage reservoirs which were filled in the winter months by pumping from the Hotham River under a license from the Department of Water or from regional water bores which are available all year round. Process water is also sourced as reclamation of water from the decant pond at the TSF.
Production royalties are payable to the WA government and are included in the net smelter return (NSR) cut-off determination. Royalty payments were first incurred in the second half of 2009.
The Boddington Operations have freehold ownership of all the eastern and central areas of operations. The western portion of the operational area is outside the freehold land, and is Crown land covered by native forest. Mining operations can be conducted in this area but with certain restrictions imposed by the State Government through the 1978 Mining Act that are applicable to forested Crown lands. The restrictions have known and manageable requirements.
The Boddington Operations area was previously subject to a land claim registered under the Native Title Act and referred to as the Gnaala Karla Booja Claim. This claim has now been settled.
22.5 Geology and Mineralization
The deposit style is still somewhat controversial. Features consistent with porphyry-style mineralization, classic orogenic shear zones, and intrusion-related gold–copper–bismuth mineralization, are all recognized, giving rise to a variety of genetic interpretations.
The geological understanding of the settings, lithologies, and structural and alteration controls on mineralization in the different zones is sufficient to support estimation of mineral resources and mineral reserves. The geological knowledge of the area is also considered sufficiently acceptable to reliably inform mine planning.
The mineralization style and setting are well understood and can support declaration of mineral resources and mineral reserves.
Newmont continues to actively explore in the Saddleback Greenstone Belt. Geophysics and surface geochemistry datasets are assisting in recognizing new belt-scale lineaments and felsic intrusions, similar to the monzogranite possibly associated with gold mineralization at Boddington, which could host additional Boddington-style mineralization. A number of possible cutbacks were identified adjacent to the current mine plan that may represent upside potential for the operations if these areas can be included in the LOM plan.
22.6 History
The Boddington Operations have over 40 years of active mining history, and exploration activities date back to 1980 when gold was first discovered.
22.7 Exploration, Drilling, and Sampling
The exploration programs completed to date are appropriate for the style of the mineralization within the Boddington Operations area.
| | | | | | | | |
Date: February, 2022 | | Page 22-2 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Drilling is normally perpendicular to the strike of the mineralization, but depending on the dip of the drill hole, and the dip of the mineralization, drill intercept widths are typically greater than true widths.
Sampling methods, sample preparation, analysis and security conducted prior to Newmont’s interest in the operations were in accordance with exploration practices and industry standards at the time the information was collected. Current Newmont sampling methods are acceptable for mineral resource and mineral reserve estimation. Sample preparation, analysis and security for the Newmont programs are currently performed in accordance with exploration best practices and industry standards.
The quantity and quality of the lithological, geotechnical, collar and down-hole survey data collected during the exploration and delineation drilling programs are sufficient to support mineral resource and mineral reserve estimation. The collected sample data adequately reflect deposit dimensions, true widths of mineralization, and the style of the deposits. Sampling is representative of the gold and copper grades in the deposit, reflecting areas of higher and lower grades.
Density measurements are considered to provide acceptable density values for use in mineral resource and mineral reserve estimation.
The sample preparation, analysis, quality control, and security procedures used by the Boddington Operations have changed over time to meet evolving industry practices. Practices at the time the information was collected were industry-standard, and frequently were industry-leading practices. The sample preparation, analysis, quality control, and security procedures are sufficient to provide reliable data to support estimation of mineral resources and mineral reserves.
The QA/QC programs adequately address issues of precision, accuracy and contamination. Modern drilling programs typically included blanks, duplicates and standard samples. QA/QC submission rates meet industry-accepted standards.
22.8 Data Verification
Newmont had data collection procedures in place that included several verification steps designed to ensure database integrity. Newmont staff also conducted regular logging, sampling, laboratory and database reviews. In addition to these internal checks, Newmont contracted independent consultants to perform laboratory, database and mine study reviews. The process of active database quality control and internal and external audits generally resulted in quality data.
The data verification programs concluded that the data collected from the Boddington Operations area adequately support the geological interpretations and constitute a database of sufficient quality to support the use of the data in mineral resource and mineral reserve estimation.
Data that were verified on upload to the database are acceptable for use in mineral resource and mineral reserve estimation.
The QP receives and reviews monthly reconciliation reports from the mine site. Through the review of these reconciliation factors the QP is able to ascertain the quality and accuracy of the
| | | | | | | | |
Date: February, 2022 | | Page 22-3 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
data and its suitability for use in the assumptions underlying the mineral resource and mineral reserve estimates.
22.9 Metallurgical Testwork
Industry-standard studies were performed as part of process development and initial mill design. Subsequent production experience and focused investigations guided mill alterations and process changes. Testwork programs, both internal and external, continue to be performed to support current operations and potential improvements. From time to time, this may lead to requirements to adjust cut-off grades, modify the process flowsheet, or change reagent additions and plant parameters to meet concentrate quality, production, and economic targets.
Samples selected for testing were representative of the various types and styles of mineralization. Samples were selected from a range of depths within the deposit. Sufficient samples were taken so that tests were performed on sufficient sample mass.
Recovery factors estimated are based on appropriate metallurgical testwork, and are appropriate to the mineralization types and the selected process routes. T The forecast LOM gold recovery is 85% and the forecast LOM copper recovery is 82%. These forecasts do not include the application of recovery degradation to long-term stockpiles of medium-grade ore. Gold recovery is discounted by 3% and copper recovery is discounted by 6% to account for recovery degradation in the business plan. These degradation assumptions were verified by an ongoing stockpile oxidation testwork program.
The mill throughput and associated recovery factors are considered appropriate to support mineral resource and mineral reserve estimation, and mine planning.
Since commissioning in 2009, the operation has actively managed the arsenic level in plant feed and, through concentrate blending techniques, controlled the level in copper concentrate shipments to below the penalty rate trigger, hence no penalties were incurred to the Report date.
Alumina remains the largest penalty element present in the copper concentrate, with shipments regularly exposed to a penalty adjustment. However, at 4–5% Al2O3 the levels are not far off the trigger point of 3% in most contracts and a modification to the process was made during Q1 2019 with the introduction of a cleaner–scalper column which reduces the non-sulfide gangue (i.e., Al2O3) in the concentrate and improves the grade of the concentrate as a result.
22.10 Mineral Resource Estimates
Newmont has a set of protocols, internal controls, and guidelines in place to support the mineral resource estimation process, which the estimators must follow.
Estimation was performed by Newmont personnel. All mineralogical information, exploration boreholes and background information were provided to the estimators by the geological staff at the mines or by exploration staff. Modelling was performed in Leapfrog, with resource estimates in Vulcan, Supervisor software and proprietary geostatistics workflows.
Mineral resources are reported using the mineral resource definitions set out in SK1300, and are reported exclusive of those mineral resources converted to mineral reserves. The reference point for the estimate is in situ.
| | | | | | | | |
Date: February, 2022 | | Page 22-4 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Factors which may affect the mineral resource estimates include: metal price assumptions; changes to the assumptions used to generate the NSR cut-off; changes to design parameter assumptions that pertain to the conceptual pit shell design that constrain the mineral resources, including changes to geotechnical, mining and metallurgical recovery assumptions, and changes to royalties levied and any other relevant parameters that are included in and impact the NSR cut-off determination; changes in interpretations of mineralization geometry and continuity of mineralization zones; changes to the dilution skin percentages used for large dolerite dykes; and assumptions as to the continued ability to access the site, retain mineral and surface rights titles, maintain the operation within environmental and other regulatory permits, and retain the social license to operate.
22.11 Mineral Reserve Estimates
Mineral reserves were converted from measured and indicated mineral resources. Inferred mineral resources were set to waste. Estimation was performed by Newmont personnel.
All current mineral reserves will be exploited using open pit mining methods or are in stockpiles. The mine plan is based on a 42 Mt/a mill throughput rate. Pit designs are full crest and toe detailed designs with final ramps based on the selected optimum Whittle cones. Pit designs honor geotechnical guidelines. The mine schedule was developed at an NSR cut-off of AU$15.32/t, incorporating the processing cost, metallurgical recovery, incremental ore mining costs, process sustaining capital and tailings dam-related rehabilitation costs.
The block models were constructed to include the expected dilution based on mining methods, bench height and other factors. The current mine and process reconciliation appears to support this assumption.
The mill processes higher-grade ores delivered from the mine at an elevated cut-off. The ore between the elevated cut-off and the marginal cut-off is stockpiled for later processing at the end of the mine life.
Stockpile estimates were based on mine dispatch data; the grade comes from closely-spaced blasthole sampling and tonnages were sourced from truck factors.
Mineral reserves are reported using the mineral reserve definitions set out in SK1300. The reference point for the estimate is the point of delivery to the process plant.
Areas of uncertainty that may materially impact the mineral reserve estimates include: changes to long-term metal price and exchange rate assumptions; changes to metallurgical recovery assumptions; changes to the input assumptions used to derive the pit designs applicable to the open pit mining methods used to constrain the estimates; changes to the forecast dilution and mining recovery assumptions; changes to the cut-off values applied to the estimates; variations in geotechnical (including seismicity), hydrogeological and mining method assumptions; and changes to environmental, permitting and social license assumptions.
22.12 Mining Methods
Mineral reserves were estimated assuming open pit mining, and the use of conventional Owner-operated equipment.
| | | | | | | | |
Date: February, 2022 | | Page 22-5 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Open pit designs were assessed and reviewed prior to pit excavation to ensure adequacy and integrity of design geometry with consideration to ground conditions. A continuous system of assessment was implemented and is adhered to during ongoing excavation processes in order to document and verify geological conditions as they were encountered.
The pit dewatering system will continuously receive large volumes of groundwater and surface run-off over the LOM. The long-term dewatering strategy assumes that this trend continues throughout the LOM. The LOM pit dewatering plan will strategically upgrade the in-pit sump pump system (passive dewatering) and dewatering-bores (active dewatering) to cope with operational needs as required.
The LOM plan currently envisages mining at an average rate of approximately 80 Mt/a for 14 years, peaking at 93 Mt/a in 2035, with a maximum rate of advance by pit stage of seven benches per annum and an average of five benches (60 m) per year. The mine life will extend to 2034 with material mined from the open pit. Milling will cease in 2035 after treatment of stockpiled ore.
As part of day-to-day operations, Newmont will continue to perform reviews of the mine plan and consider alternatives to, and variations within, the plan. Alternative scenarios and reviews may be based on ongoing or future mining considerations, evaluation of different potential input factors and assumptions, and corporate directives.
22.13 Recovery Methods
The process plant design was based on a combination of metallurgical testwork, previous study designs, previous operating experience. The design is conventional to the gold industry and has no novel parameters.
The plant will produce variations in recovery due to the day-to-day changes in ore type or combinations of ore type being processed. These variations are expected to trend to the forecast recovery value for monthly or longer reporting periods.
22.14 Infrastructure
The majority of the key infrastructure to support the mining activities envisaged in the LOM is in place. A second TSF will be required for the LOM plan. Within Newmont’s ground holdings, there is sufficient area to allow construction of any additional infrastructure that may be required in the future.
Personnel live either surrounding settlements or stay at the accommodation village.
A number of WRSFs are in use, segregated as oxide or rock facilities. Potentially acid-forming waste is encapsulated as required.
Stockpiles are reclaimed using a preferential high-grade feed strategy, with the lower medium-grade stockpiles being re-handled to the mill towards the end of the LOM. The stockpiles are reclaimed using conventional mining fleet and loading units.
The F1/F3 residue disposal area (RDA) is the current active TSF for the Boddington Operations.
| | | | | | | | |
Date: February, 2022 | | Page 22-6 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
The current F1/F3 dam has approved capacity to 600 Mt which is sufficient storage for the life of mine reserves to 2025, assuming remaining capacity of 163 Mt, and a 40 Mt/a process rate. The approved facility has 11 perimeter embankments, of which all are in place.
Newmont plans to expand the facility to 750 Mt, which, assuming the same 40 Mt/a process rate, will provide tailings capacity to 2029. The expansion to 750 Mt is not currently permitted. There is sufficient time for Newmont to obtain approval for the TSF expansion prior to 2025, when it is required.
Additional storage that will be required for the LOM beyond 2029 is being evaluated by Newmont. This is currently envisaged as a new RDA with a 250 Mt capacity. Newmont has established a pathway and a timeline for the RDA approval and construction such that storage capacity will be available when needed. There is sufficient time for Newmont to obtain approval for the second RDA prior to 2029, when it is required.
The TSF is operated as a zero-discharge facility; all water is returned to the process facility for reuse.
Process water is supplied direct from the mine pits, from onsite storage reservoirs which were filled in the winter months by pumping from the Hotham River under a license from the Department of Water or from regional water bores which are available year-round. Process water is also sourced as reclamation of water from the decant pond at the TSF.
Power is sourced from the Bluewater Power Station, and transmitted through the State power grid from the power station to the mine site.
22.15 Market Studies
Newmont has an internal marketing department that is tasked with monitoring global commodities markets, including the products from the Boddington Operations. The operations produce a gold–copper concentrate. Newmont has contracts in place for the majority of the copper concentrate. The terms contained within the concentrate sales contracts are typical and consistent with standard industry practice for high-gold, low-copper concentrates. The contracts include industry benchmark terms for metal payables, treatment charges and refining charges for concentrates produced. Depending on the specific contract, the terms for the sale of the copper concentrate are either annually negotiated, benchmark-based treatment and refining charges, or a combination of annually-negotiated terms.
Newmont’s bullion is sold on the spot market, by marketing experts retained in-house by Newmont. The terms contained within the sales contracts are typical and consistent with standard industry practice and are similar to contracts for the supply of doré elsewhere in the world.
The largest in-place contracts other than for product sales cover items such as bulk commodities, operational and technical services, mining and process equipment, and administrative support services. Contracts are negotiated and renewed as needed. Contract terms are typical of similar contracts in Australia that Newmont is familiar with.
| | | | | | | | |
Date: February, 2022 | | Page 22-7 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
22.16 Environmental, Permitting and Social Considerations
Baseline and supporting environmental studies were completed to assess both pre-existing and ongoing site environmental conditions, as well as to support decision-making processes during operations start-up and restart. Characterization studies were completed for all environmental media including soil, water, waste, air, noise and closure. Plans were developed and implemented to address aspects of operations such as waste and fugitive dust management, spill prevention and contingency planning, water management, and noise levels.
There are five species classified as Threatened Species/Matters of National Environmental Significance in the Project area. All five species have site-specific management plans.
The most recent closure plan was submitted in 2019. The closure estimate, as at 2021, assuming operations to 2036, is calculated as approximately AU$0.5 B.
All major permits and approvals are either in place or Newmont expects to obtain them in the normal course of business. Additional permitting will be required to support the tailings disposal required in the LOM plan. Where permits have specific terms, renewal applications are made of the relevant regulatory authority as required, prior to the end of the permit term.
The operations area is subject to the South West Native Title Settlement.
Newmont has well-established relationships, engagement forums, and a suite of integrated social impact and opportunity-aligned strategic investment partnerships.
22.17 Capital Cost Estimates
Capital costs were based on recent prices or operating data and are at a minimum at a pre-feasibility level of confidence, having an accuracy level of ±25% and a contingency range not exceeding 15%.
Capital costs included funding for infrastructure, pit dewatering, development drilling, and permitting as well as miscellaneous expenditures required to maintain production. Mobile equipment re-build/replacement schedules and fixed asset replacement and refurbishment schedules were included. Sustaining capital costs reflected current price trends.
The overall capital cost estimate for the LOM is AU$1.8 B.
22.18 Operating Cost Estimates
Operating costs were based on actual costs seen during operations and are projected through the LOM plan, and are at a minimum at a pre-feasibility level of confidence, having an accuracy level of ±25% and a contingency range not exceeding 15%.
Historical costs were used as the basis for operating cost forecasts for supplies and services unless there are new contract terms for these items. Labor and energy costs were based on budgeted rates applied to headcounts and energy consumption estimates.
The operating cost estimate for the LOM is AU$11.7 B.
| | | | | | | | |
Date: February, 2022 | | Page 22-8 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
22.19 Economic Analysis
The NPV5% is US$2.1 B. As the cashflows are based on existing operations where all costs are considered sunk to 1 January 2022, considerations of payback and internal rate of return are not relevant.
22.20 Risks and Opportunities
Factors that may affect the mineral resource and mineral reserve estimates were identified in Chapter 11.13 and Chapter 12.9 respectively.
22.20.1 Risks
The risks associated with the Boddington site are generally those expected with a large surface mining operation and include the accuracy of the resource model, unexpected geological features that cause geotechnical issues, dewatering difficulties and/or operational impacts.
Other risks noted include:
•Commodity price increases for key consumables such diesel, electricity, tires and chemicals would negatively impact the stated mineral reserves and mineral resources;
•Labor cost increases or productivity decreases could also impact the stated mineral reserves and mineral resources, or impact the economic analysis that supports the mineral reserves;
•While the autonomous haulage system is currently operational any unforeseen issues with this innovative system could increase costs and/or lower expected productivities;
•With bauxite mining having precedence over other minerals there is a risk that any unexpected requirement to advance bauxite mining (or delay gold mining) could increase costs and/or delay the expected production profile;
•Geotechnical and hydrological assumptions used in mine planning are based on historical performance, and to date historical performance has been a reasonable predictor of current conditions. Any changes to the geotechnical and hydrological assumptions could affect mine planning, affect capital cost estimates if any major rehabilitation is required due to a geotechnical or hydrological event, affect operating costs due to mitigation measures that may need to be imposed, and impact the economic analysis that supports the mineral reserve estimates;
•The mine plan assumes that the existing TSF can be expanded from 600 Mt to 750 Mt. While there is sufficient time for the permitting process prior to the expansion being required in 2025, if there is a delay in the permitting process or the facility cannot be expanded, this could impact the mine plan, the mineral reserve estimates and the economic analysis that supports the mineral reserve estimates;
•The mine plan assumes that a second RDA can be constructed and permitted. Newmont has established a pathway and a timeline to develop additional tailings capacity such that storage capacity will be available when needed. However, if there are changes to the assumed pathway, to the ability to construct and permit such a facility, or to the timeline
| | | | | | | | |
Date: February, 2022 | | Page 22-9 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
assumptions, this could impact the mine plan, the mineral reserve estimates and the economic analysis that supports the mineral reserve estimates;
•The mineral reserve estimates are very sensitive to metal prices. Lower metal prices than forecast in the LOM plan may require revisions to the mine plan, with impacts to the mineral reserve estimates and the economic analysis that supports the mineral reserve estimates;
•There are five species classified as Threatened Species/Matters of National Environmental Significance in the Project area. Although there are site-specific management plans in place, if there is a major impact seen on the populations from mining activities, the environmental permits for the operations could be revised or even revoked. The social license to operate could also be impacted;
•Climate changes could impact operating costs and ability to operate;
•There is a risk to the Boddington Operations overall if the Worsley JV were to fail to renew the mining leases, as Newmont’s interest relies on the existence of valid mining tenure.
22.20.2 Opportunities
Opportunities for the Boddington mine include moving the stated mineral resources into mineral reserves through additional drilling and study work. The mineral reserves and mineral resources are based on conservative price estimates for gold and copper so upside exists, either in terms of the potential to estimate additional mineral reserves and mineral resources or improved economics should the prices used for gold and copper be increased.
Opportunities include:
•Conversion of some or all of the measured and indicated mineral resources currently reported exclusive of mineral reserves to mineral reserves, with appropriate supporting studies;
•Upgrade of some or all of the inferred mineral resources to higher-confidence categories, such that such better-confidence material could be used in mineral reserve estimation;
•Higher metal prices than forecast could present upside sales opportunities and potentially an increase in predicted Project economics;
•Potential to link the north and south pits through the saddle area to form a single large open pit through mining and economic studies.
22.21 Conclusions
Under the assumptions presented in this Report, the Boddington Operations have a positive cash flow, and mineral reserve estimates can be supported.
| | | | | | | | |
Date: February, 2022 | | Page 22-10 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
23.0 RECOMMENDATIONS
As Boddington is an operating mine, the QP has no material recommendations to make.
| | | | | | | | |
Date: February, 2022 | | Page 23-1 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
24.0 REFERENCES
24.1 Bibliography
Allibone, A.H., Windh, J., Etheridge, M.A., Burton, D., Anderson, G., Edwards, P., Miller, A., Graves, C., Fanning, C.M., and Wysoczanski, R., 1998: Timing Relationships and Structural Controls on the Location of Au–Cu Mineralization at the Boddington Gold Mine, Western Australia: Economic Geology, 93, pp. 245–270.
AMMTEC, 1989: Assessment of Australian Assay Laboratories Boddington Facility: unpublished internal report by AMMTEC to Boddington Gold Mine.
ANCOLD, 2019: Guidelines on Tailings Dams – Planning, Design, Construction, Operation and Closure: July 2019, Revision 1.
AngloGold Ashanti Australia, 2001: AngloGold Inputs for 1999 Wandoo Resource Assessment and the Derivation of a Factor for the Economic Model: unpublished internal report by AngloGold Ashanti Australia to NBGJV, October 2001.
AngloGold Ashanti Australia, 2003: Boddington Joint Venture, 2003 AngloGold–BGM Collaborative Study — Boddington Gold Mine Exploration Data Review and Target Generation: unpublished internal report NBGJV, December 2003.
AngloGold Ashanti Australia, 2004a: Boddington – Drill Hole Bias Examination: unpublished internal report by AngloGold Ashanti Australia to NBGJV, February 2004.
AngloGold Ashanti Australia, 2004b: Boddington Basement Pits Grade Control Information Examination: unpublished internal report by AngloGold Ashanti Australia to NBGJV, March 2004.
AngloGold Ashanti Australia, 2004c: Boddington Geology and Domain Review: unpublished internal report by AngloGold Ashanti Australia to NBGJV, June 2004.
Augenstein, C. et.al. 2012: Boddington Geological Campaign 2012: unpublished internal report by Jigsaw Geoscience to NBG, November 2012.
Barley M.E., Groves D.I. and Blake T.S., 1992: Archaean metal deposits related to tectonics: evidence from Western Australia, Perth, Western Australia: Geology Department and University Extension, University of Western Australia Publication 22, p. 307–324.
Boddington Gold Mining Company, 2003: Review of AGAA Estimation Domains: internal NBGJV report, October 2003.
Boddington Gold Mining Company, 2004a: FSU Local Resource Estimate Quality, Mining Dilution and Recovery Review: internal NBGJV report, January 2004.
Boddington Gold Mining Company, 2004b: Recommended Configuration of the FSU Phase 3 Local Resource Estimate: internal NBGJV report, December 2004.
Douglas, I., 2004: Boddington Drill Hole Bias Investigations: internal memorandum from Newmont Gold Corp. to NBGJV, 4 April, 2004.
Fluor Australia Pty Ltd, 2000: Boddington Expansion Feasibility Study Update: internal report by Fluor Australia Pty Ltd to Boddington Gold Mine, Volume 1 (Executive Summary), Volume 2 (Geology and Resource), Volume 3 (Mining) and Volume 4 (Process).
| | | | | | | | |
Date: February, 2022 | | Page 24-1 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Gleeson, K., Tangney, G., Behn, M., and Hutchin, S., 1999: Boddington Gold Mine — Wandoo Project, Wandoo South and North Geology Report, Volume 1: internal report by Boddington Gold Mine.
Golder Associates, 2002: Report on Geological Modeling and Recoverable Resource Estimation of the Wandoo Deposit: internal report by Golder Associates to NBGJV, May 2002.
Golder Associates, 2002: Review of the Effects of Potential Check Assay Biases: unpublished internal report by Golder Associates to NBGJV, May 2002.
Golder Associates, 2003: Report on 2003 Multiple Indicator Kriging Resource Estimate of the Wandoo Deposit, Boddington Gold Mine: internal report by Golder Associates to NBGJV, May 2003.
Golder Associates, 2004a: Kriging Neighborhood Analysis and Re-estimation of the Boddington Gold Mine Expansion Resource Model: internal report by Golder Associates to NBGJV, April 2004.
Golder Associates, 2004b: Review of Acid Rock Drainage Studies for the Boddington Expansion Project: internal report by Golder Associates to NBGJV, April 2004.
Golder Associates, 2005a: Local Resource Estimates for the Boddington Gold Mine Expansion: internal report by Golder Associates to NBGJV, February 2005.
Golder Associates, 2005b: Global Resource Simulation Study for the Boddington Gold Mine Expansion: internal report by Golder Associates to NBGJV, June 2005.
Golder Associates, 2005c: BGME Probability-Based Resource Classification Using Simulations: internal report by Golder Associates to NBGJV, September 2005.
Golder Associates, 2017a: Technical Review of Mineral Resources and Mineral Reserves: internal report by Golder Associates to NBG, May 2017.
Golder Associates, 2017b: Newmont Boddington 2017 Preliminary Ore Reserve: internal report by Golder Associates to NBG, November 2017.
Golder Associates, 2018: Technical Review of 2017 Mineral Resource Update: internal report by Golder Associates to NBG, January 2018.
Kenny, K., Tangney, G., and Rowell, A., 2002: Boddington Expansion Project Wandoo Mineral Resource: internal report by AngloGold Ashanti Australia to NBGJV.
Kirkham, R.V., 1972: Porphyry Deposits: in Blackadar, R.G., ed., Report of Activities Part B, November 1971 to March 1972: Geological Survey of Canada, Paper 72-1b, pp. 62–64.
Knight Piesold Consulting, 2016: F1/F3 Residue Disposal Area 2015 RDA Cone Penetration Testing: internal report by Knight Piesold Consulting to NBG, February 2016
Libby, W.G. and DeLaeter, J.R., 1998: Biotite Rb-Sr Age Evidence for Early Palaeozoic Tectonism and the Cratonic Margin in Southwestern Australia: Australian Journal of Earth Sciences, vol 45, pp. 623–632.
Masters, S., 2008: Audit of the BGM 2007 Resource Model, Boddington Mine, WA: internal report byCS-2 Pty Ltd to NBGJV, September 2008.
| | | | | | | | |
Date: February, 2022 | | Page 24-2 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
McCuaig, T., and Behn, M., 2001: Boddington Gold Mine: Nature of the Mineralisation in the Wandoo North Basement Resource and Refinements to the Model for Genesis of Mineralisation at Wandoo: internal report by SRK Consulting to NBGJV.
McCuaig, T.C, Behn, M.T., Stein, H., Hagemann, S.G., McNaughton, N., Cassidy, K,F., Champion, D., and Wyborn, L., 2002: The Boddington Gold Mine: a new style of Archaean Au–Cu deposit: in WA Gold Giants, MSc Short Course Notes, Centre for Global Metallogeny, University of WA, pp. 61–64.
Miller, A., Behn, M., and Gleeson K., 1996: Wandoo Prospect Geological Report, Volume 1: internal report by Boddington Gold Mine.
Newmont Mining Corporation, 2014b: Geotechnical Study for Hard Rock Slope Design at Newmont Boddington Gold, 20130328-GT-PROJ-AT- Hard Rock Study Report Final, March 2014.
Newmont Mining Corporation, 2016: 75Deg Steepening Trails: internal report, GT-GM060-20161026-AGJ-FINAL, October 2016.
Newmont Mining Ltd. 2004a: NML Review of Boddington Project Resource: internal report by Newmont Mining Ltd to NBGJV, January 2004.
Newmont Mining Ltd, 2004b: Boddington Drill Hole Bias Investigations: internal report by Newmont to NBGJV, April 2004.
Peattie R., 2004: Boddington Drillhole Bias Examination: internal memorandum from AngloGold Ashanti to NBGJV, 19 February 2004.
Petrucci, P., 2014: Metallurgical Performance Model Update 2014, Newmont Boddington Gold: internal report by Boddington Gold Mine.
Petrucci, P., 2015: 2015 Gold Recovery Function Update, Newmont Boddington Gold: internal report by Boddington Gold Mine.
Petrucci, P., 2021: Impact of Stockpile Oxidation on Recovery at NBG: Newmont Boddington Gold, unpublished internal report by Boddington Gold Mine.
Quantitative Geoscience, 2003: Audit of the 2003 Boddington Resource Estimate: unpublished internal report by Quantitative Geoscience to NBGJV, October 2003.
Ravenscroft, P., 2007: Review of Gold Resource Modeling Methodology, Boddington Mine, WA: internal report by CS-2 Pty Ltd to NBGJV, August 2007.
Roberts, M., 2012: Metallurgical Performance Models, Newmont Boddington Gold: internal report by Boddington Gold Mine.
Rossi, M., 2009: 2009 UC Resource Model Independent Audit Report, Boddington Gold Mine: internal report by GeoSystems International Inc to NBG, September 2009.
Roth, E., 1992: The Nature and Genesis of Archaean Porphyry-Style Cu–Au–Mo Mineralisation at the Boddington Gold Mine, Western Australia: Ph.D. thesis, University of Western Australia.
Runge, K.,2012: Evaluation of Recovery Function Predictions – February 2012: internal report by Metso Process Technology & Innovation to NBG
| | | | | | | | |
Date: February, 2022 | | Page 24-3 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
Sillitoe, R. H., 2000: Gold-Rich Porphyry Deposits: Descriptive and Genetic Models and their Role in Exploration and Discover: in Gold in 2000, Reviews in Economic Geology, Vol. 13, Society of Economic Geologists.
Sinclair, W.D., 2006: Consolidation and Synthesis of Mineral Deposits Knowledge - Porphyry Deposits: report posted to Natural Resources Canada website 30 January 2006, 14 http://gsc.nrcan.gc.ca/mindep/synth_dep/porph/index_e.php>.
Snowden Consulting, 2012: 2235: Geotechnical Assessment of Fresh Rock Pit Cut-back: April 2012.
SRK Consulting, 2005: Deleterious Elements Modeling: internal report by SRK Consulting to NBGJV, May 2005.
SRK Consulting, 2012. NEM008: Boddington Gold Mine: Geotechnical Study for Final Saprolite Slopes: February 2012.
Stein, H.J., Markey, R.J., Morgan, J.W., Selby, D., Creaser, R.A., McCuaig, T.C., and Behn M., 2001: Re-Os Dating of Boddington Molybdenite, SW Yilgarn: Two Au Mineralization Events: report posted to University of Alberta website.
Stoker, P., 2000: Audit Boddington Expansion QA/QC: internal report to NBGJV, September 2000.
Stoker, P., 2001: Review of Additional QA/QC Data, Boddington Expansion: internal report to NBGJV, February 2001.
Stoker, P., 2002: Review of BGM QA/QC Assay Data, Boddington Expansion: internal report to NBGJV, January 2002.
Surman, J., 1999: Boddington Gold Mine Audit of data used in preparation for the Wandoo Bedrock Resource Estimation: internal report by Snowden Mining Industry Consultants to Boddington Gold Mine.
Symons, P.M., Anderson, G., Beard, T.J., Hamilton, L.M., Reynolds, G.D., Robinson, J.M., Staley, R.W., and Thompson, C.M., 1990: Boddington Gold Deposit: in Geology of the Mineral Deposits of Australia and Papua New Guinea, ed. F. E. Hughes, Australasian Institute of Mining and Metallurgy Monograph 14, Volume 1, pp. 165–169.
Tangney, G., 2000: Boddington Gold Mine Basement Gold Assay Quality Control: internal memorandum by Boddington Gold Mine.
Wilde, S. A., 1976: The Saddleback Group – A Newly-Discovered Archaean Greenstone Belt in the Southwestern Yilgarn Block: Western Australian Geological Survey Annual Report 1975, pp. 92–95.
24.2 Abbreviations and Symbols
| | | | | |
Abbreviation/Symbol | Term |
AAL | Australian Assay Laboratories |
AARL | Anglo American Research Laboratory |
AAS | Atomic Absorption Spectrometry |
Alcoa | Alcoa of Australia Ltd. |
Amdel | Amdel Laboratory |
| | | | | | | | |
Date: February, 2022 | | Page 24-4 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
| | | | | |
Abbreviation/Symbol | Term |
ARD | acid rock drainage |
AU$ | Australian dollar |
BGJV | Boddington Gold Joint Venture |
BGMJV | Boddington Gold Mine Joint Venture |
BHP | BHP Minerals Ltd. |
CIM | Canadian Institute of Mining, Metallurgy and Petroleum |
CNwad | weak acid-dissociable cyanide |
CRF | capital recovery factor |
CST | cleaner scavenger tailings |
DGPS | digital global positioning system |
G&A | general and administrative |
Genalysis | Genalysis Laboratory |
GPS | global positioning system |
HPGR | high pressure grinding rolls |
ICP-AES | inductively-coupled plasma atomic emission spectroscopy |
ICP-MS | inductively coupled plasma–mass spectrometry |
ICP-OES | inductively coupled plasma-optical emission spectroscopy |
JORC | Joint Ore Reserve Committee |
LOM | life-of-mine |
MMI | mobile metal ion |
MPa | |
NAPP | net acid-producing potential |
NBG | Newmont Boddington Gold |
NBGJV | Newmont Boddington Gold Joint Venture |
Newmont | Newmont Corporation; formerly Newmont Mining Corporation |
NSR | net smelter return |
OK | ordinary kriging |
QA/QC | Quality assurance and quality control |
QP | Qualified Person |
RAB | rotary air blast |
RC | reverse circulation |
RDA | residue disposal area |
Reynolds | Reynolds Australia Alumina Ltd. |
RL | Relative level |
ROM | run-of-mine |
RQD | rock quality description |
SAG | semi-autogenous grind |
SG | Specific gravity |
Shell | The Shell Company of Australia Ltd. |
SME | Society for Mining, Metallurgy and Exploration |
SMU | selective mining unit |
TSF | tailing storage facility |
UltraTrace | UltraTrace Geoanalytical Laboratories |
US | United States |
| | | | | | | | |
Date: February, 2022 | | Page 24-5 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
| | | | | |
Abbreviation/Symbol | Term |
WA | Western Australia |
WA Heritage Act | Aboriginal Heritage Act 1972 (WA) |
Worsley | Worsley Alumina Pty Ltd |
Worsley JV | Worsley Alumina Joint Venture |
24.3 Glossary of Terms
| | | | | |
Term | Definition |
acid rock drainage/acid mine drainage | Characterized by low pH, high sulfate, and high iron and other metal species. |
amphibolite facies | one of the major divisions of the mineral-facies classification of metamorphic rocks, the rocks of which formed under conditions of moderate to high temperatures (500° C, or about 950° F, maximum) and pressures. Amphibole, diopside, epidote, plagioclase, almandine and grossular garnet, and wollastonite are minerals typically found in rocks of the amphibolite facies |
ANFO | A free-running explosive used in mine blasting made of 94% prilled aluminum nitrate and 6% No. 3 fuel oil. |
ball mill | A piece of milling equipment used to grind ore into small particles. It is a cylindrical shaped steel container filled with steel balls into which crushed ore is fed. The ball mill is rotated causing the balls themselves to cascade, which in turn grinds the ore. |
bullion | Unrefined gold and/or silver mixtures that have been melted and cast into a bar or ingot. |
Caro’s acid | A reagent (H2SO5)generated through the combination of hydrogen peroxide and sulfuric acid, used in cyanide destruction and detoxification. |
comminution/crushing/grinding | Crushing and/or grinding of ore by impact and abrasion. Usually, the word "crushing" is used for dry methods and "grinding" for wet methods. Also, "crushing" usually denotes reducing the size of coarse rock while "grinding" usually refers to the reduction of the fine sizes. |
concentrate | The concentrate is the valuable product from mineral processing, as opposed to the tailing, which contains the waste minerals. The concentrate represents a smaller volume than the original ore |
cut-off grade | A grade level below which the material is not “ore” and considered to be uneconomical to mine and process. The minimum grade of ore used to establish reserves. |
cyanidation | A method of extracting gold or silver by dissolving it in a weak solution of sodium cyanide. |
data verification | The process of confirming that data has been generated with proper procedures, has been accurately transcribed from the original source and is suitable to be used for mineral resource and mineral reserve estimation |
decline | A sloping underground opening for machine access from level to level or from the surface. Also called a ramp. |
density | The mass per unit volume of a substance, commonly expressed in grams/ cubic centimeter. |
development | Often refers to the construction of a new mine or; Is the underground work carried out for the purpose of reaching and opening up a mineral deposit. It includes shaft sinking, cross-cutting, drifting and raising. |
dilution | Waste of low-grade rock which is unavoidably removed along with the ore in the mining process. |
easement | Areas of land owned by the property owner, but in which other parties, such as utility companies, may have limited rights granted for a specific purpose. |
electrowinning. | The removal of precious metals from solution by the passage of current through an electrowinning cell. A direct current supply is connected to the anode and cathode. As current passes through the cell, metal is deposited on the cathode. When sufficient metal has been deposited on the cathode, it is removed from the cell and the sludge rinsed off the plate and dried for further treatment. |
| | | | | | | | |
Date: February, 2022 | | Page 24-6 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
| | | | | |
Term | Definition |
elution | Recovery of the gold from the activated carbon into solution before zinc precipitation or electro-winning. |
EM | Geophysical method, electromagnetic system, measures the earth's response to electromagnetic signals transmitted by an induction coil |
encumbrance | An interest or partial right in real property which diminished the value of ownership, but does not prevent the transfer of ownership. Mortgages, taxes and judgements are encumbrances known as liens. Restrictions, easements, and reservations are also encumbrances, although not liens. |
feasibility study | A feasibility study is a comprehensive technical and economic study of the selected development option for a mineral project, which includes detailed assessments of all applicable modifying factors, as defined by this section, together with any other relevant operational factors, and detailed financial analysis that are necessary to demonstrate, at the time of reporting, that extraction is economically viable. The results of the study may serve as the basis for a final decision by a proponent or financial institution to proceed with, or finance, the development of the project. A feasibility study is more comprehensive, and with a higher degree of accuracy, than a pre-feasibility study. It must contain mining, infrastructure, and process designs completed with sufficient rigor to serve as the basis for an investment decision or to support project financing. |
flotation | Separation of minerals based on the interfacial chemistry of the mineral particles in solution. Reagents are added to the ore slurry to render the surface of selected minerals hydrophobic. Air bubbles are introduced to which the hydrophobic minerals attach. The selected minerals are levitated to the top of the flotation machine by their attachment to the bubbles and into a froth product, called the "flotation concentrate." If this froth carries more than one mineral as a designated main constituent, it is called a "bulk float". If it is selective to one constituent of the ore, where more than one will be floated, it is a "differential" float. |
flowsheet | The sequence of operations, step by step, by which ore is treated in a milling, concentration, or smelting process. |
frother | A type of flotation reagent which, when dissolved in water, imparts to it the ability to form a stable froth |
gangue | The fraction of ore rejected as tailing in a separating process. It is usually the valueless portion, but may have some secondary commercial use |
greenschist facies | one of the major divisions of the mineral facies classification of metamorphic rocks, the rocks of which formed under the lowest temperature and pressure conditions usually produced by regional metamorphism. Temperatures between 300 and 450 °C (570 and 840 °F) and pressures of 1 to 4 kilobars are typical. The more common minerals found in such rocks include quartz, orthoclase, muscovite, chlorite, serpentine, talc, and epidote |
high pressure grinding rolls (HPGR) | A type of crushing machine consisting of two large studded rolls that rotate inwards and apply a high pressure compressive force to break rocks. |
indicated mineral resource | An 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 term adequate geological evidence means evidence that is sufficient to establish geological and grade or quality continuity with reasonable certainty. 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. |
inferred mineral resource | An 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 term limited geological evidence means evidence that is only sufficient to establish that geological and grade or quality continuity is more likely than not. 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. A qualified person must have a reasonable expectation that the majority of inferred mineral resources could be upgraded to indicated or measured mineral resources with continued exploration; and should be able to defend the basis of this expectation before his or her peers. |
| | | | | | | | |
Date: February, 2022 | | Page 24-7 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
| | | | | |
Term | Definition |
initial assessment | An initial assessment is a preliminary technical and economic study of the economic potential of all or parts of mineralization to support the disclosure of mineral resources. The initial assessment must be prepared by a qualified person and must include appropriate assessments of reasonably assumed technical and economic factors, together with any other relevant operational factors, that are necessary to demonstrate at the time of reporting that there are reasonable prospects for economic extraction. An initial assessment is required for disclosure of mineral resources but cannot be used as the basis for disclosure of mineral reserves |
internal rate of return (IRR) | The rate of return at which the Net Present Value of a project is zero; the rate at which the present value of cash inflows is equal to the present value of the cash outflows. |
IP | Geophysical method, induced polarization; used to directly detect scattered primary sulfide mineralization. Most metal sulfides produce IP effects, e.g., chalcopyrite, bornite, chalcocite, pyrite, pyrrhotite |
JORC code | The Australasian Code for Reporting of Mineral Resources and Ore Reserves prepared by the Joint Ore Reserves Committee of the Australasian Institute of Mining and Metallurgy, Australian Institute of Geoscientists and Mineral Council of Australia, as amended. Provides minimum standards for public reporting to ensure that investors and their advisers have all the information they would reasonably require for forming a reliable opinion on the results and estimates being reported. Adopted by the ASX for reporting ore body size and mineral concentrations. |
life of mine (LOM) | Number of years that the operation is planning to mine and treat ore, and is taken from the current mine plan based on the current evaluation of ore reserves. |
lithogeochemistry | The chemistry of rocks within the lithosphere, such as rock, lake, stream, and soil sediments |
locked cycle flotation test | A standard laboratory flotation test where certain intermediate streams are recycled into previous separation stages and the test is repeated across a number of cycles. This test provides a more realistic prediction of the overall recovery and concentrate grade that would be achieved in an actual flotation circuit, compared with a more simple batch flotation test. |
measured mineral resource | A 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 term conclusive geological evidence means evidence that is sufficient to test and confirm geological and grade or quality continuity. 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 this section, in sufficient detail to support detailed mine planning and final evaluation of the economic viability of the deposit. |
mill | Includes any ore mill, sampling works, concentration, and any crushing, grinding, or screening plant used at, and in connection with, an excavation or mine. |
| | | | | | | | |
Date: February, 2022 | | Page 24-8 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
| | | | | |
Term | Definition |
mineral reserve | A 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. The determination that part of a measured or indicated mineral resource is economically mineable must be based on a preliminary feasibility (pre-feasibility) or feasibility study, as defined by this section, conducted by a qualified person applying the modifying factors to indicated or measured mineral resources. Such study must demonstrate that, at the time of reporting, extraction of the mineral reserve is economically viable under reasonable investment and market assumptions. The study must establish a life of mine plan that is technically achievable and economically viable, which will be the basis of determining the mineral reserve. The term economically viable means that the qualified person has determined, using a discounted cash flow analysis, or has otherwise analytically determined, that extraction of the mineral reserve is economically viable under reasonable investment and market assumptions. The term investment and market assumptions includes all assumptions made about the prices, exchange rates, interest and discount rates, sales volumes, and costs that are necessary to determine the economic viability of the mineral reserves. The qualified person must use a price for each commodity that provides a reasonable basis for establishing that the project is economically viable. |
mineral resource | A 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. The term material of economic interest includes mineralization, including dumps and tailings, mineral brines, and other resources extracted on or within the earth’s crust. It does not include oil and gas resources, gases (e.g., helium and carbon dioxide), geothermal fields, and water. When determining the existence of a mineral resource, a qualified person, as defined by this section, must be able to estimate or interpret the location, quantity, grade or quality continuity, and other geological characteristics of the mineral resource from specific geological evidence and knowledge, including sampling; and conclude that there are reasonable prospects for economic extraction of the mineral resource based on an initial assessment, as defined in this section, that he or she conducts by qualitatively applying relevant technical and economic factors likely to influence the prospect of economic extraction. |
net present value (NPV) | The present value of the difference between the future cash flows associated with a project and the investment required for acquiring the project. Aggregate of future net cash flows discounted back to a common base date, usually the present. NPV is an indicator of how much value an investment or project adds to a company. |
net smelter return (NSR) | A defined percentage of the gross revenue from a resource extraction operation, less a proportionate share of transportation, insurance, and processing costs. |
open pit | A mine that is entirely on the surface. Also referred to as open-cut or open-cast mine. |
ounce (oz) (troy) | Used in imperial statistics. A kilogram is equal to 32.1507 ounces. A troy ounce is equal to 31.1035 grams. |
overburden | Material of any nature, consolidated or unconsolidated, that overlies a deposit of ore that is to be mined. |
penalty elements | Elements that when recovered to a flotation concentrate, attract a penalty payment from the smelting customer. This is because those elements are deleterious, and cause quality, environmental or cost issues for the smelter. Includes elements such as As, Hg and Pb. |
plant | A group of buildings, and especially to their contained equipment, in which a process or function is carried out; on a mine it will include warehouses, hoisting equipment, compressors, repair shops, offices, mill or concentrator. |
| | | | | | | | |
Date: February, 2022 | | Page 24-9 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
| | | | | |
Term | Definition |
preliminary feasibility study, pre-feasibility study | A preliminary feasibility study (prefeasibility study) is a comprehensive study of a range of options for the technical and economic viability of a mineral project that has advanced to a stage where a qualified person has determined (in the case of underground mining) a preferred mining method, or (in the case of surface mining) a pit configuration, and in all cases has determined an effective method of mineral processing and an effective plan to sell the product. A pre-feasibility study includes a financial analysis based on reasonable assumptions, based on appropriate testing, about the modifying factors and the evaluation of any other relevant factors that are sufficient for a qualified person to determine if all or part of the indicated and measured mineral resources may be converted to mineral reserves at the time of reporting. The financial analysis must have the level of detail necessary to demonstrate, at the time of reporting, that extraction is economically viable |
probable mineral reserve | A probable mineral reserve is the economically mineable part of an indicated and, in some cases, a measured mineral resource. For a probable mineral reserve, the qualified person’s confidence in the results obtained from the application of the modifying factors and in the estimates of tonnage and grade or quality is lower than what is sufficient for a classification as a proven mineral reserve, but is still sufficient to demonstrate that, at the time of reporting, extraction of the mineral reserve is economically viable under reasonable investment and market assumptions. The lower level of confidence is due to higher geologic uncertainty when the qualified person converts an indicated mineral resource to a probable reserve or higher risk in the results of the application of modifying factors at the time when the qualified person converts a measured mineral resource to a probable mineral reserve. A qualified person must classify a measured mineral resource as a probable mineral reserve when his or her confidence in the results obtained from the application of the modifying factors to the measured mineral resource is lower than what is sufficient for a proven mineral reserve. |
proven mineral reserve | A proven mineral reserve is the economically mineable part of a measured mineral resource. For a proven mineral reserve, the qualified person has a high degree of confidence in the results obtained from the application of the modifying factors and in the estimates of tonnage and grade or quality. A proven mineral reserve can only result from conversion of a measured mineral resource. |
qualified person | A qualified person is an individual who is a mineral industry professional with at least five years of relevant experience in the type of mineralization and type of deposit under consideration and in the specific type of activity that person is undertaking on behalf of the registrant; and an eligible member or licensee in good standing of a recognized professional organization at the time the technical report is prepared. For an organization to be a recognized professional organization, it must: (A) Be either: (1) An organization recognized within the mining industry as a reputable professional association, or (2) A board authorized by U.S. federal, state or foreign statute to regulate professionals in the mining, geoscience or related field; (B) Admit eligible members primarily on the basis of their academic qualifications and experience; (C) Establish and require compliance with professional standards of competence and ethics; (D) Require or encourage continuing professional development; (E) Have and apply disciplinary powers, including the power to suspend or expel a member regardless of where the member practices or resides; and; (F) Provide a public list of members in good standing. |
reclamation | The restoration of a site after mining or exploration activity is completed. |
refining | A high temperature process in which impure metal is reacted with flux to reduce the impurities. The metal is collected in a molten layer and the impurities in a slag layer. Refining results in the production of a marketable material. |
| | | | | | | | |
Date: February, 2022 | | Page 24-10 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
| | | | | |
Term | Definition |
resistivity | Observation of electric fields caused by current introduced into the ground as a means of studying earth resistivity in geophysical exploration. Resistivity is the property of a material that resists the flow of electrical current |
rock quality designation (RQD) | A measure of the competency of a rock, determined by the number of fractures in a given length of drill core. For example, a friable ore will have many fractures and a low RQD. |
rod mill | A rotating cylindrical mill which employs steel rods as a grinding medium. |
royalty | An amount of money paid at regular intervals by the lessee or operator of an exploration or mining property to the owner of the ground. Generally based on a specific amount per tonne or a percentage of the total production or profits. Also, the fee paid for the right to use a patented process. |
run-of-mine (ROM) | Rehandle where the raw mine ore material is fed into the processing plant’s system, usually the crusher. This is where material that is not direct feed from the mine is stockpiled for later feeding. Run-of-mine relates to the rehandle being for any mine material, regardless of source, before entry into the processing plant’s system. |
semi-autogenous grinding (SAG) | A method of grinding rock into fine powder whereby the grinding media consists of larger chunks of rocks and steel balls. |
specific gravity | The weight of a substance compared with the weight of an equal volume of pure water at 4°C. |
strike length | The horizontal distance along the long axis of a structural surface, rock unit, mineral deposit or geochemical anomaly. |
supergene | Mineral enrichment produced by the chemical remobilization of metals in an oxidized or transitional environment. |
tailings | Material rejected from a mill after the recoverable valuable minerals have been extracted. |
| | | | | | | | |
Date: February, 2022 | | Page 24-11 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
25.0 RELIANCE ON INFORMATION PROVIDED BY THE REGISTRANT
25.1 Introduction
The QP fully relied on the registrant for the information used in the areas noted in the following sub-sections. The QP considers it reasonable to rely on the registrant for the information identified in those sub-sections, for the following reasons:
•The registrant has been owner and operator of the gold mining operations for over 10 years;
•The registrant has employed industry professionals with expertise in the areas listed in the following sub-sections;
•The registrant has a formal system of oversight and governance over these activities, including a layered responsibility for review and approval;
•The registrant has considerable experience in each of these areas.
25.2 Macroeconomic Trends
•Information relating to inflation, interest rates, discount rates, exchange rates, and taxes was obtained from the registrant.
This information is used in the economic analysis in Chapter 19. It supports the assessment of reasonable prospects for economic extraction of the mineral resource estimates in Chapter 11, and inputs to the determination of economic viability of the mineral reserve estimates in Chapter 12.
25.3 Markets
•Information relating to market studies/markets for product, market entry strategies, marketing and sales contracts, product valuation, product specifications, refining and treatment charges, transportation costs, agency relationships, material contracts (e.g., mining, concentrating, smelting, refining, transportation, handling, hedging arrangements, and forward sales contracts), and contract status (in place, renewals), was obtained from the registrant.
This information is used in the economic analysis in Chapter 19. It supports the assessment of reasonable prospects for economic extraction of the mineral resource estimates in Chapter 11, and inputs to the determination of economic viability of the mineral reserve estimates in Chapter 12.
25.4 Legal Matters
•Information relating to the corporate ownership interest, the mineral tenure (concessions, payments to retain property rights, obligations to meet expenditure/reporting of work conducted), surface rights, water rights (water take allowances), royalties, encumbrances,
| | | | | | | | |
Date: February, 2022 | | Page 25-1 |
| | | | | |
Boddington Operations Western Australia Technical Report Summary | |
| |
easements and rights-of-way, violations and fines, permitting requirements, and the ability to maintain and renew permits was obtained from the registrant.
This information is used in support of the property description and ownership information in Chapter 3, the permitting and mine closure descriptions in Chapter 17, and the economic analysis in Chapter 19. It supports the reasonable prospects of economic extraction for the mineral resource estimates in Chapter 11, and the assumptions used in demonstrating economic viability of the mineral reserve estimates in Chapter 12.
25.5 Environmental Matters
•Information relating to baseline and supporting studies for environmental permitting, environmental permitting and monitoring requirements, ability to maintain and renew permits, emissions controls, closure planning, closure and reclamation bonding and bonding requirements, sustainability accommodations, and monitoring for and compliance with requirements relating to protected areas and protected species was obtained from the registrant.
This information is used when discussing property ownership information in Chapter 3, the permitting and closure discussions in Chapter 17, and the economic analysis in Chapter 19. It supports the reasonable prospects of economic extraction for the mineral resource estimates in Chapter 11, and the assumptions used in demonstrating economic viability of the mineral reserve estimates in Chapter 12.
25.6 Stakeholder Accommodations
•Information relating to social and stakeholder baseline and supporting studies, hiring and training policies for workforce from local communities, partnerships with stakeholders (including national, regional, and state mining associations; trade organizations; fishing organizations; state and local chambers of commerce; economic development organizations; non-government organizations; and, state and federal governments), and the community relations plan was obtained from the registrant.
This information is used in the social and community discussions in Chapter 17, and the economic analysis in Chapter 19. It supports the reasonable prospects of economic extraction for the mineral resource estimates in Chapter 11, and the assumptions used in demonstrating economic viability of the mineral reserve estimates in Chapter 12.
25.7 Governmental Factors
•Information relating to taxation and royalty considerations at the Project level, monitoring requirements and monitoring frequency, bonding requirements, and violations and fines was obtained from the registrant.
This information is used in the discussion on royalties and property encumbrances in Chapter 3, the monitoring, permitting and closure discussions in Chapter 17, and the economic analysis in Chapter 19. It supports the reasonable prospects of economic extraction for the mineral resource estimates in Chapter 11, and the assumptions used in demonstrating economic viability of the mineral reserve estimates in Chapter 12.
| | | | | | | | |
Date: February, 2022 | | Page 25-2 |
Ahafo Operations
Ghana
Technical Report Summary
Report current as of:
December 31, 2021
Qualified Person:
Mr. Donald Doe, RM SME.
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
NOTE REGARDING FORWARD-LOOKING INFORMATION
This Technical Report Summary contains forward-looking statements within the meaning of the U.S. Securities Act of 1933 and the U.S. Securities Exchange Act of 1934 (and the equivalent under Canadian securities laws), that are intended to be covered by the safe harbor created by such sections. Such forward-looking statements include, without limitation, statements regarding Newmont’s expectation for its mines and any related development or expansions, including estimated cash flows, production, revenue, EBITDA, costs, taxes, capital, rates of return, mine plans, material mined and processed, recoveries and grade, future mineralization, future adjustments and sensitivities and other statements that are not historical facts.
Forward-looking statements address activities, events, or developments that Newmont expects or anticipates will or may occur in the future and are based on current expectations and assumptions. Although Newmont’s management believes that its expectations are based on reasonable assumptions, it can give no assurance that these expectations will prove correct. Such assumptions, include, but are not limited to: (i) there being no significant change to current geotechnical, metallurgical, hydrological and other physical conditions; (ii) permitting, development, operations and expansion of operations and projects being consistent with current expectations and mine plans, including, without limitation, receipt of export approvals; (iii) political developments in any jurisdiction in which Newmont operates being consistent with its current expectations; (iv) certain exchange rate assumptions being approximately consistent with current levels; (v) certain price assumptions for gold, copper, silver, zinc, lead and oil; (vi) prices for key supplies being approximately consistent with current levels; and (vii) other planning assumptions.
Important factors that could cause actual results to differ materially from those in the forward-looking statements include, among others, risks that estimates of mineral reserves and mineral resources are uncertain and the volume and grade of ore actually recovered may vary from our estimates, risks relating to fluctuations in metal prices; risks due to the inherently hazardous nature of mining-related activities; risks related to the jurisdictions in which we operate, uncertainties due to health and safety considerations, including COVID-19, uncertainties related to environmental considerations, including, without limitation, climate change, uncertainties relating to obtaining approvals and permits, including renewals, from governmental regulatory authorities; and uncertainties related to changes in law; as well as those factors discussed in Newmont’s filings with the U.S. Securities and Exchange Commission, including Newmont’s latest Annual Report on Form 10-K for the period ended December 31, 2021, which is available on www.newmont.com.
Newmont does not undertake any obligation to release publicly revisions to any “forward-looking statement,” including, without limitation, outlook, to reflect events or circumstances after the date of this document, or to reflect the occurrence of unanticipated events, except as may be required under applicable securities laws. Investors should not assume that any lack of update to a previously issued “forward-looking statement” constitutes a reaffirmation of that statement. Continued reliance on “forward-looking statements” is at investors’ own risk.
| | | | | | | | |
Date: February 2022 | | Page a |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
CONTENTS
| | | | | | | | |
Date: February 2022 | | Page 1-i |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
| | | | | | | | |
Date: February 2022 | | Page 1-ii |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
| | | | | | | | |
Date: February 2022 | | Page 1-iii |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
| | | | | | | | |
Date: February 2022 | | Page 1-iv |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
| | | | | | | | |
Date: February 2022 | | Page 1-v |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
| | | | | | | | |
Date: February 2022 | | Page 1-vi |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
| | | | | | | | |
Date: February 2022 | | Page 1-vii |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
TABLES
| | | | | | | | |
Date: February 2022 | | Page 1-viii |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
FIGURES
| | | | | |
| |
| |
| |
| |
| |
| |
| |
| |
Figure 6-4: Drill Section, Apensu Deeps | |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| | | | | | | | |
Date: February 2022 | | Page 1-ix |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
1.0 EXECUTIVE SUMMARY
1.1 Introduction
This technical report summary (the Report) was prepared for Newmont Corporation (Newmont) on the Ahafo Operations (Ahafo Operations or the Project) located in the Republic of Ghana (Ghana).
Newmont has three subsidiaries registered under the laws of Ghana: Newmont Ghana Gold Ltd. (NGGL), Newmont Golden Ridge Ltd. (NGRL) and Moydow Limited (Moydow). For the purposes of this Report, the name Newmont is used interchangeably for the subsidiary and parent companies.
1.2 Terms of Reference
The Report was prepared to be attached as an exhibit to support mineral property disclosure, including mineral resource and mineral reserve estimates, for the Ahafo Operations in Newmont’s Form 10-K for the year ending December 31, 2021.
Mineral resources are reported for Apensu, Awonsu and Subika open pits, and Subika and Apensu underground. Mineral reserves are reported for Subika and Awonsu open pits and Subika underground. Mineral reserves are also estimated for material in stockpiles.
Unless otherwise indicated, all financial values are reported in United States dollars (US$). Unless otherwise indicated, the metric system is used in this Report. Mineral resources and mineral reserves are reported using the definitions in Regulation S–K 1300 (SK1300), under Item 1300. The Report uses US English. The Report contains forward-looking information; refer to the note regarding forward-looking information at the front of the Report.
1.3 Property Setting
The Ahafo Operations are located in western Ghana near the towns of Kenyasi and Ntotroso in the Ahafo Region, about 290 km northwest of Accra. The operations are 107 km northwest of Kumasi, and 40 km south of the regional capital of Sunyani. Road access to the Ahafo Operations is via Route 6, an asphalt-paved road from Accra to the Tepa Junction via Kumasi in the direction of Sunyani. From Tepa Junction, an asphalt-paved road leads west for 39 km to Hwidiem. A paved road then leads northwest for 8 km to the town of Kenyasi. Sunyani is a major regional center and is the source of supplies and fuel. Workers live in the surrounding communities.
The Project area falls within the wet semi-equatorial climatic zone of Ghana. The Ahafo Operations are conducted year-round.
The local topography comprises low rounded hills with elevations ranging from 110–540 masl. Two streams, the Subri and the Awonsu, drain from the Project area to the Tano River.
The Project shares a boundary with the Bosumkese Forest Reserve, and the Amoma Shelterbelt Forest Reserve bisects the Ahafo mining lease.
| | | | | | | | |
Date: February 2022 | | Page 1-1 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
1.4 Ownership
The Project is held through Newmont Ghana Gold Ltd., an indirectly-wholly owned Newmont subsidiary.
1.5 Mineral Tenure, Surface Rights, Water Rights, Royalties and Agreements
The Ahafo mining lease is separated into two areas, where Ahafo South is in Area A, and Ahafo North in Area B. Ahafo North is planned to be developed as a stand-alone operation and is not included in this Report.
Newmont currently holds three mining licenses, and nine prospecting licenses that in total cover an area of approximately 952 km2. The mining leases are current until 2031 and can be renewed by negotiation. The total area held under mining licenses is approximately 549 km2. The current mine take area is approximately 54 km2, and represents the area that has been fully compensated. Approximately 44 km2 has not been fully compensated (e.g., payment would be necessary to move people from their land).
The prospecting licenses are valid and are in good standing. The total area covered by prospecting licenses is about 403 km2.
Under Ghanaian law, only mining leases and prospecting licenses require surveys; reconnaissance license types are delineated by latitude/longitude co-ordinates. All of the Ahafo mining leases were surveyed by Newmont staff.
A number of payments are required to keep the licenses/leases in good standing, and include an annual rental that is payable by January of each year, and annual prospecting and mining permit payments, which are payable by January of each year. All required payments have been made as they fall due.
Newmont was granted a Plan of Operations (PoO) for the Ahafo Operations, and may use whatever land is necessary for its operations, but must respect the surface rights of other land users in relation to access and loss of crops, timber, or structures. Extensive title searches were conducted over the mining lease areas and no titles exist that would categorically exclude Newmont’s operations on the Project lands. Newmont’s indenture for surface lands will run concurrently with the life of the operations, but will extend for no more than 50 years.
Newmont holds permits to allow abstraction of groundwater, surface water, and water from the Tano River and discharge of water from its water storage facility.
The Government of Ghana has a 10% free-carried, fixed, non-equity, interest in the Ahafo Operations. Newmont pays the Government of Ghana a ninth of the dividend declared to Newmont shareholders. Since December 2015, Newmont has been obligated to pay 0.6% of the operational revenue if the gold price averages US$1,300/oz or higher, as an advance dividend against the one-ninth share.
A Revised Investment Agreement (the Agreement) between Newmont and the Government of Ghana defines and fixes, in specific terms, the effective corporate tax and royalty burden the Project will carry during operations. The Agreement establishes a fixed fiscal and legal regime, including sliding-scale royalty and tax rates for the duration of the Agreement’s stability period.
| | | | | | | | |
Date: February 2022 | | Page 1-2 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Under the Agreement stability period, which now extends until the end of 2025, the tax rate will remain at 32.5%. After the cessation of the stability period, the tax rate will increase to 35%. During the stability period, Newmont will pay gross royalties on gold doré production in accordance with a sliding scale of 3–5%, tied to the gold price. After the Agreement ends, the royalty rate will be fixed at 5%.
A net smelter return (NSR) royalty of 2.0% is payable on all ounces produced from the Rank (formerly Ntotroso) concession. The royalty is paid to Franco-Nevada Corporation (Franco-Nevada), which acquired the royalty for US$58 M in November 2009. The majority of the Subika deposit, the northern portion of the Awonsu deposit, and the southern tip of the Amoma deposit fall within the Rank mining lease boundary.
An additional 0.6% is payable as a special fee for gold doré production from designated Forest Reserves.
1.6 Geology and Mineralization
The deposits that comprise the Ahafo Operations are considered to be examples of orogenic gold deposits.
Mineralization is developed in a Birimian succession that includes the Paleoproterozoic volcano–sedimentary Sefwi Belt, the Sunyani Basin and the Kumasi Basin. Three granite successions have intruded the Birimian rocks, including Cape Coast granitoids, Dixcove-type granitoids, and post-Tarkwaian granitoids.
Dixcove suite or “belt-type” granitoid rocks intrude the contact and are common in the metavolcanic rocks that form more or less elongate bodies parallel to the regional strike. Regional structure is controlled by the Kenyasi Thrust Fault; a northeast- to southwest-trending regional thrust fault that separates the Sefwi Belt from the Sunyani Basin. Mineralization consists of vein-style gold deposits, hosted in shear zones associated with the Kenyasi Thrust Fault.
Two distinct deposit styles are recognized within the Ahafo Operations. Kenyasi-style deposits, comprising Apensu, Awonsu, and Amoma, are associated with the Kenyasi Thrust Fault, along a sheared thrust contact between Dixcove Suite granitoids and footwall volcano-sedimentary units. Subika-style mineralization comprises gold that is entirely hosted in Dixcove granitoids, in the hanging wall of the Kenyasi Thrust Fault. To date, the only recognized deposit of the style is Subika.
Gold typically occurs as native gold, associated with pyrite. Alteration associated with the deposits includes silicification, albitization, pyritization, and carbonation.
1.7 History and Exploration
Exploration prior to Newmont’s Project interest was conducted by Normandy Mining Ltd. and associated companies. Work completed included geochemical sampling (sediment and soil), geological mapping, prospect evaluation and drilling, and mining studies.
Since Project acquisition in early 2002, Newmont has completed exploration drilling, collection of deep-sensing geochemical samples, airborne and ground geophysical surveys, environmental, geotechnical, mining and metallurgical studies. Open pit mining commenced in
| | | | | | | | |
Date: February 2022 | | Page 1-3 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
2006. A permitted underground trial mining program was conducted at Subika from 2012–2013, and commercial production from Subika underground was achieved in November 2018.
The Project area remains prospective. Within the immediate mining area, exploration potential includes the following:
•Subika: testing for extensions of the mineralization to the northeast, and down plunge of the currently-defined limits of the deposit;
•Apensu: drill testing of the northern strike and plunge extensions to the Apensu North mineralized shoot and Gap area depth potential.
•Subika–Apensu: potential mineralization along the deep linking structures between Subika Underground and Apensu Deeps;
•Awonsu: potential mineralization extents below the existing pit.
Near-mine exploration is planned to include:
•Evaluating structurally-favorable zones and potential repetitions along and down-plunge of the Kenyasi Thrust between the Apensu South and Awonsu deposits;
•Testing down plunge depth extensions to Subika;
•Amoma: potential for mineralization extensions below the existing pit;
•Drill testing of Subika structures and adjacent parallel fault trends defined by aeromagnetic, gradient array resistivity, 3D gravity models, geochemical datasets, and projections of the important, secondary, shallow-angle, low permeability faults which focus mineralization;
Drill testing previously identified geochemical and geophysical anomalies where these are potentially within trucking distance of the Ahafo process plant.
1.8 Drilling and Sampling
1.8.1 Drilling
A total of 12,902 drill holes (approximately 1.8 Mm) was completed within the Ahafo Operations area to December 31, 2021, including 4,792 core holes (1,321,915 m), 3,597 reverse circulation (RC) holes drill holes (234,566 m), 1,475 RC pre-collar/core tail holes (207,837 m), and 1,154 aircore drill holes (34,393 m).
Geological logging varies between drill types, but typically includes lithologies, alteration, sulfide content, oxidation states and presence of water. Core hole logging also records significant contacts, fractures, veins, and faults, core recovery and rock quality designation (RQD).
Except for the first few meters of individual RC holes, where recovery is typically in the 20–40% range, recovery is generally about 95–98%. Core recovery is normally 100% except for very rare times when drilling encounters fault and graphitic shear zones.
Drill collar locations have been recorded by surveyors using a number of methods, including optical instruments, or digital global positioning system (GPS) equipment. Downhole survey instrumentation included Welnav cameras, multi-shot Sperry-sun and Reflex single-shot and multi-shot downhole survey instruments. Depending on the drill type and program date, data were collected at 10–12 m depth, followed by surveys on 30 m intervals.
| | | | | | | | |
Date: February 2022 | | Page 1-4 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Grade control drilling employs blast hole rigs on an approximate 4 m x 4.5 m spacing in both ore and waste zones. Blastholes are sampled by cutting a trench across the thickest portion of the cuttings pile and collecting the sample from the trench. Approximately 7 kg of sample is taken from one side of the trenched walls through the blast hole cuttings. If a duplicate sample is required from the blasthole, it is taken from the opposite wall of the trench.
1.8.2 Hydrogeology
Water quality monitoring done on site is based on a monitoring plan developed to guide ongoing sampling and analysis of process fluid including groundwater and surface water collected in conjunction with Newmont’s water resources monitoring program to meet operational needs and environmental protection requirements.
A groundwater model was developed in 2016 by Golder Associates, Africa, for the Ahafo Operations, primarily to support the open pit mines and the planned Subika underground mine. Evaluations of the potential to also underground mine adjacent to the Apensu open pit required updates to the groundwater model.
To the Report date, the hydrogeological data collection programs have provided data suitable for use in the mining operations, and have supported the assumptions used in the active pits and the Subika underground mine.
1.8.3 Geotechnical
The following general information are collected for geotechnical assessment of both open pit and underground excavations:
•Rockmass classification and characterization data to estimate the rock quality;
•Structural data to determine potential structural-controlled failures;
•Damage mapping data to determine stress-related failures.
A fall-of-ground register is maintained for all rock events, which provides brief summary of sequence and nature of the rock event.
Run-of-mine (ROM) waste rock is used as fill material in the underground excavations. The suitability of the fill material is determined via the mechanical properties of the rock and fragmentation analysis to define material granularity and appropriateness.
The geological hard rock setting at the Ahafo Operations is well understood and displays consistency in the various open pits located on site. Additional testing continues to confirm the consistency of material strengths and parameters.
1.8.4 Sampling and Assay
RC samples are generally taken on 1 m intervals down hole. Core sample lengths vary from 0.2–1.5 m, with sample intervals chosen based on the geologic features of the rock including alteration.
Density (specific gravity) determinations were typically performed using water displacement methods.
| | | | | | | | |
Date: February 2022 | | Page 1-5 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Independent primary laboratories used for sample preparation and analysis included Transworld Laboratories in Tarkwa, Ghana, SGS Laboratories in Bibiani/Tarkwa, Ghana (SGS), ALS Chemex in Kumasi, Ghana, ALS Chemex in Vancouver, Canada, ALS Chemex in Johannesburg, South Africa (collectively ALS), and UltraTrace Laboratory Pty Ltd in Perth, Western Australia (UltraTrace). SGS was the primary laboratory for all drill programs for the period June 2003 to 2010, and ALS has been the primary laboratory since. Both SGS and ALS are independent laboratory groups that operate globally, and the SGS/ALS laboratories used for the Project are accredited to ISO/IEC17025 for selected sample preparation and analytical techniques.
The on-site mine laboratory, SGS Ahafo, is used to prepare and analyze grade control, and metallurgical samples. It is also used as the sample preparation and analysis facility for exploration/development drill holes; there is a separate sample preparation site that has dedicated equipment and is only used to process exploration samples. The on-site mine laboratory holds ISO/IEC17025 accreditation.
Sample preparation procedures varied by sample type. Soil, rock chip, pit, aircore, and RC samples were crushed to either a nominal 90% passing -2 mm size fraction or a nominal 90% passing -3 mm size fraction. All samples were pulverized to a nominal 90% passing -75 µm. Core samples were crushed to a nominal 90% passing -2 mm size fraction, then pulverized to a nominal 95% passing 75 µm. Analytical methods employed included inductively-coupled plasma mass spectrometry (ICP-MS), atomic absorption spectrometry (AAS), and fire assay with an AAS finish.
1.8.5 Quality Assurance and Quality Control
Newmont has considerably modified the quality assurance and quality control (QA/QC) program at Ahafo from that used prior to 2004. Newmont maintains a QA/QC program for the Ahafo Operations. This includes regular submissions of blank, duplicate and standard reference materials (standards) in samples sent for analysis. Results are regularly monitored. Data for all three duplicate types indicates that the data are acceptably precise at both primary laboratories.
1.9 Data Verification
Newmont personnel regularly visit the laboratories that process Newmont samples to inspect sample preparation and analytical procedures.
The database that supports mineral resource and mineral reserve estimates is checked using electronic data scripts and triggers. Newmont also conducted a number of internal data verification programs since obtaining its Project interest. Newmont also conducts internal audits, termed Reserve and Resource Review (3R) audits, of all its operations. The most recent Ahafo Operations 3R audits were conducted in 2012, 2014, 2016, 2018, and 2020. Earlier audits, known as Five Star reviews, were undertaken in 2005 and 2006. The 2020 3R audit found that the Ahafo Operations were generally adhering to Newmont’s internal standards and guidelines with respect to the estimation of mineral resources and mineral reserves.
Data verification was performed by external consultants in support of mine development and operations. No material issues were identified in the reviews.
| | | | | | | | |
Date: February 2022 | | Page 1-6 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
The QP receives and reviews monthly reconciliation reports from the mine site. These reports include the industry standard reconciliation factors for tonnage, grade and metal. Through the review of these reconciliation factors the QP is able to ascertain the quality and accuracy of the data and its suitability for use in the assumptions underlying the mineral resource and mineral reserve estimates.
1.10 Metallurgical Testwork
Metallurgical testwork was conducted at Newmont Metallurgical Services and Hazen Research under the direction of Newmont personnel. An earlier phase of testwork in 2000 was completed under the direction of and interpreted by Lycopodium Pty Ltd.
Samples selected for metallurgical testing during feasibility and development studies were representative of the various styles of mineralization within the different deposits. Samples were selected from a range of locations within the deposit zones. Sufficient samples were taken and tests were performed using sufficient sample mass for the respective tests undertaken. Each year, samples are selected to represent the next three years of production in mine-to-mill testing, to ensure there sufficient current testwork to support knowledge of the mill feed materials, and support process assumptions. Samples are currently selected for every 300,000 t of ore to be processed, using a grade/tonnage table, and used in mine-to-mill testing.
Work completed included mineralogy, Bond, rod and ball mill work indices, abrasion indices and JKTech drop weight comminution parameters, grind size assessments, heap leaching, gravity concentration, cyanide leaching, reagent consumption, determination of thickening and slurry pumping characteristics, tailings geochemistry, and rheology tests.
The feed to the plant is currently both primary and oxide ore. Based on the life of mine plan, it is expected that the remaining 202 kt of stockpiled oxide ore will be processed in 2022. Average throughput projection is 9.5Mt per annum from 2022 to the end of mine life.
Recovery models were derived at a grind size of P80 106 µm, based on actual testwork conducted at current plant conditions, for the various deposits. These equations were used to determine the block by block recovery and the individual blocks recoveries were coded into the model for floating cones. Depending on the deposit recoveries over the life-of-mine (LOM) range from 81–94%. Stockpiled material is tracked by pit source and is assigned the same metallurgical recovery as the deposit it is sourced from.
The Ahafo ores are clean ores containing low levels of problematic elements. No appreciable levels of rich-solution-robbing materials are present in the ores. The ores contain low sulfide sulfur, and low concentrations of primary cyanide consumers (copper, nickel and zinc), which suggest that cyanide consumption may increase.
1.11 Mineral Resource Estimation
1.11.1 Estimation Methodology
Database closeout dates varied by deposit. Geological models were constructed using Vulcan geological modeling software. Block models were built with cell dimensions that were appropriate to the deposit style, orientation and dimensions of the mineralization. Exploratory data analysis made use of tools such as descriptive statistics, histograms, cumulative probability
| | | | | | | | |
Date: February 2022 | | Page 1-7 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
plots, box plots, and contact analysis of raw assays to guide the construction of the block model and the development of estimation plans. Specific gravity values were assigned to the block model based on oxidation surfaces. Grade caps were determined from raw assay or composite statistics for each geology domain. Composite lengths vary by deposit, and range from 2–8 m. Spatial variability of the gold grades was examined using correlograms and/or variograms.
All deposits were estimated using ordinary kriging (OK) interpolation methods. Grade estimations were selective by mineralization domains in most cases and restricted within a +0.2 g/t Au grade shell for open pit models and +2.0 g/t Au for underground models. The underground models (Subika underground and Apensu Deeps) were constrained within their mineralized shapes. Depending on the deposit, the minimum and maximum numbers of samples that were required to estimate a block (by domain) ranged from one to 30. Based on the relationships observed in the different variogram ranges, octant restrictions were implemented. Sample searches were tailored in such a manner that three to four drill holes were included along the strike of the ellipsoid, two to three drill holes were included perpendicular to strike and one to two composites were selected in the cross-plane direction. The high yield method was employed during the Subika open pit update to avoid including high-grade samples when estimating distant blocks.
Validation used Newmont-standard methods, including a combination of visual checks, swath plots, global statistical bias checks against input data, alternate estimation methods and reconciliation with historical mine/plant performance. The validation procedures indicated that the geology and resource models used are acceptable to support the mineral resource estimation.
Mineral resource classification was undertaken based primarily on drill spacing and number of drill holes used in the estimate. Mineral resources were classified as measured, indicated, and inferred. A quantitative assessment of geological risk was undertaken using Newmont-standard methods and applied on a block by block basis. Primary risks to resource quality include quantity and spacings of drill data, geological knowledge, geological interpretation and grade estimates. All identified risks are within acceptable tolerances with associated management plans.
Mineral resources considered amenable to open pit mining methods are reported within a mine design. Variable incremental cut-off grades that range from 0.39–0.40 g/t Au in saprolite to 0.52–0.57 g/t Au in transition/fresh material were used in the inputs. Mineral resources considered amenable to underground mining methods are reported within underground stope designs. Variable incremental cut-off grades that range from 2.0–2.4 g/t Au were used in the inputs.
Commodity prices used in resource estimation are based on long-term analyst and bank forecasts, supplemented with research by Newmont’s internal specialists. The estimated timeframe used for the price forecasts is the 11-year LOM that supports the mineral reserve estimates.
1.11.2 Mineral Resource Statement
Mineral resources are reported using the definitions set out in SK1300. The reference point for the estimate is in situ. Mineral resources are current as at December 31, 2021. Mineral resources are reported exclusive of those mineral resources converted to mineral reserves.
| | | | | | | | |
Date: February 2022 | | Page 1-8 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Mineral resources that are not mineral reserves do not have demonstrated economic viability. Mineral resources are reported on a 100% basis. The Government of Ghana has a 10% free-carried interest in the Project. Newmont has a 90% interest.
The measured and indicated mineral resource estimates for the Ahafo Operations are summarized in Table 1-1. The inferred mineral resource estimates are summarized in Table 1-2.
1.11.3 Factors That May Affect the Mineral Resource Estimate
Factors that may affect the mineral resource estimate include: changes to long-term metal price assumptions; changes in local interpretations of mineralization geometry and continuity of mineralized zones; changes to geological and grade shape and geological and grade continuity assumptions; changes to input parameters used in the pit shells and stope outlines constraining the mineral resources; changes to the cut-off grades used to constrain the estimates; variations in geotechnical, mining, and processing recovery assumptions; and changes to environmental, permitting and social license assumptions.
1.12 Mineral Reserve Estimation
1.12.1 Estimation Methodology
Measured and indicated mineral resources were converted to mineral reserves. Mineral reserves are estimated for the Awonsu deposit, assuming open pit mining, and the Subika deposit, assuming open pit and underground mining. Stockpiled material is also included in the mineral reserves estimates. All inferred blocks are classified as waste in the cashflow analysis that supports mineral reserve estimation.
| | | | | | | | |
Date: February 2022 | | Page 1-9 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Table 1-1: Measured and Indicated Mineral Resource Statement
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Measured Mineral Resources | Indicated Mineral Resources | Measured and Indicated Mineral Resources |
Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) |
Open pit | 500 | 0.56 | 10 | 30,000 | 1.16 | 1,120 | 30,500 | 1.15 | 1,130 |
Underground | — | — | — | 16,600 | 3.99 | 2,120 | 16,600 | 3.99 | 2,120 |
Ahafo Total | 500 | 0.56 | 10 | 46,600 | 2.16 | 3,240 | 47,100 | 2.15 | 3,250 |
Table 1-2: Inferred Mineral Resource Statement
| | | | | | | | | | | |
Area | Inferred Mineral Resources |
Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) |
Open pit | 13,500 | 1.3 | 570 |
Underground | 10,800 | 3.3 | 1,160 |
Ahafo Total | 24,300 | 2.2 | 1,730 |
Notes to Accompany Mineral Resource Tables:
1. Mineral resources are current as at December 31, 2021. Estimates are reported using the definitions in SK1300. The Qualified Person responsible for the estimate is Mr. Donald Doe, RM SME, Group Executive, Reserves, a Newmont employee.
2. The reference point for the mineral resource estimate is in situ.
3. Mineral resources are reported on a 100% basis. Newmont holds a 90% interest and the Government of Ghana has a 10% free-carried interest.
4. Mineral resources are reported exclusive of mineral reserves. Mineral resources that are not mineral reserves do not have demonstrated economic viability.
5. Mineral resources that are potentially amenable to open pit mining methods are constrained within a designed pit shell. Mineral resources that are potentially amenable to underground mining methods are constrained within conceptual stope designs. Parameters used are summarized in Table 11-1 (open pit) and Table 11-2 (underground).
6. Tonnages are metric tonnes rounded to the nearest 100,000. Gold grade is rounded to the nearest 0.01 gold grams per tonne. Gold ounces are estimates of metal contained in tonnages and do not include allowances for processing losses. Contained (cont.) gold ounces are reported as troy ounces, rounded to the nearest 10,000. Rounding of tonnes and contained metal content as required by reporting guidelines may result in apparent differences between tonnes, grade and contained metal content. Due to rounding, some cells may show a zero (“0”).
7. Totals may not sum due to rounding.
| | | | | | | | |
Date: February 2022 | | Page 1-10 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
1.12.1.1 Open Pit
The Geovia Whittle pit optimization program (Whittle 4.7.3) was used to perform a Lerchs–Grossmann optimization in support of mineral reserves reporting for mineralization amenable to open pit mining methods. A safety crown pillar of 25 m is left between the base of the Subika Phase 4 pit and the top of the Subika underground stopes. This pillar will not be mined and thus makes Phase 4 the final open pit limit for the Subika deposit.
For mineral reserves, Newmont applies a time discount factor to the dollar value block model that is generated in the pit-limit analysis, to account for the fact that a pit will be mined over a period of years, and that the cost of waste stripping in the early years must bear the cost of the time value of money. Optimization work involved floating pit shells at a series of gold prices. The generated nested pit shells were evaluated using the reserve gold price of US$1,200/oz and an 8% discount rate. The pit shells with the highest NPV were selected for detailed engineering design work.
A realistic schedule was developed in order to determine the optimal pit shell; schedule inputs include the minimum mining width, and vertical rate of advance, mining rate and mining sequence. Whittle analysis indicated a two-stage pit development was the best option for Awonsu, using a minimum mining width of 50 m. Subika mining is in the final stage with limited potential to grow at depth because of the underground crown pillar. No changes were made to the Phase 4 pit design for Subika. The minimum mining width between the Subika Phase 4 and the mined-out third phase is 50 m. All operating pits are mined on 8 m benches. Mining dilution and recovery are included in the block model, based on historic reconciliation.
1.12.1.2 Underground
The mine plan assumes two mining methods:
•Sub-level shrinkage stoping (SLS);
•Long-hole open stoping (LHOS).
Stopes were created using Deswik Stope Optimizer software at the required stope height, length and cut-off criteria based on the mine area. The stope widths depend on the stope cut-off and dilution (over-break) added to stope design, and the mining method used. A stope recovery of 90% is expected in all mining areas. Dilution is projected to average 7.6%.
1.12.1.3 Stockpiles
Stockpile estimates were based on mine dispatch data; the grade comes from closely-spaced blasthole sampling and tonnage sourced from truck factors. The stockpile volumes were typically updated based on monthly surveys. The average grade of the stockpiles was adjusted based on the material balance to and from the stockpile.
1.12.1.4 Commodity Prices
Commodity prices used in mineral reserve estimation are based on long-term analyst and bank forecasts, supplemented with research by Newmont’s internal specialists. The estimated timeframe used for the price forecasts is the 11-year LOM.
| | | | | | | | |
Date: February 2022 | | Page 1-11 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
1.12.2 Mineral Reserve Statement
Mineral reserves have been classified using the definitions set out in SK1300. The reference point for the mineral reserve estimate the point of delivery to the process facilities. Mineral reserves are current as at December 31, 2021. Mineral reserves are reported on a 100% basis. The Government of Ghana has a 10% free-carried interest in the Project. Newmont has a 90% interest.
Mineral reserves are summarized in Table 1-3. Tonnages in the table are metric tonnes.
1.13 Factors That May Affect the Mineral Reserve Estimate
Factors that may affect the mineral reserve estimates include: changes to long-term metal price assumptions; changes in local interpretations of mineralization geometry and continuity of mineralized zones; changes to geological and grade shape and geological and grade continuity assumptions; changes to input parameters used in the pit shells and stope outlines constraining the mineral reserves; changes to the cut-off grades used to constrain the estimates; variations in geotechnical, mining, and processing recovery assumptions; and changes to environmental, permitting and social license assumptions.
1.14 Mining Methods
1.14.1 Open Pit
Open pit mining is conducted using conventional techniques and an Owner-operated conventional truck and shovel fleet.
Open pit design uses defined geotechnical domains together with rock mass quality ratings for the principal lithologies and appropriate pit design criteria that reflect expected conditions and risk. Inter-ramp angles vary by deposit and pit wall lithology, and range from 30–55º.
The active pits are currently mining below the water table. Pit dewatering uses a combination of perimeter and in-pit dewatering wells, in-pit sumps, and horizontal drains. A network of monitoring piezometers is installed around all of the operating pits.
The LOM plan currently envisages mining at an average rate of approximately 26 Mt/a for nine years and peaking at 32.2 Mt/a in 2022 with a maximum rate of advance by pit stage of eight benches per annum and an average of six benches (48 m) per year. The mine life will extend to 2030 with material mined from the open pit. Milling will cease in 2032 after treatment of stockpiled ore.
| | | | | | | | |
Date: February 2022 | | Page 1-12 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Table 1-3: Proven and Probable Mineral Reserve Statement
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Proven Mineral Reserves | Probable Mineral Reserves | Proven and Probable Mineral Reserves |
Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) |
Open pit | 11,800 | 2.35 | 890 | 39,700 | 1.67 | 2,140 | 51,400 | 1.83 | 3,020 |
Underground | 9,400 | 3.76 | 1,140 | 12,700 | 2.68 | 1,100 | 22,200 | 3.14 | 2,240 |
Stockpile l | 28,300 | 0.92 | 830 | — | — | — | 28,300 | 0.92 | 830 |
Ahafo Total | 49,500 | 1.80 | 2,860 | 52,400 | 1.92 | 3,240 | 101,900 | 1.86 | 6,090 |
Notes to Accompany Mineral Reserves Table:
1.Mineral reserves are current as at December 31, 2021. Mineral reserves are reported using the definitions in SK1300. The Qualified Person responsible for the estimate is Mr. Donald Doe, RM SME, Group Executive, Reserves, a Newmont employee.
2.The reference point for the mineral reserves is the point of delivery to the process plant.
3.Mineral reserves are reported on a 100% basis. Newmont holds a 90% interest and the Government of Ghana has a 10% free-carried interest.
4.Mineral reserves that are estimated using open pit mining methods are constrained within a pit design based on an optimized Lerchs–Grossmann pit shell. Parameters used are shown in Table 12-1 for the open pit mineral reserves and Table 12-2 and Table 12-3 for the underground mineral reserves.
5.Tonnages are metric tonnes rounded to the nearest 100,000. Gold grade is rounded to the nearest 0.01 gold grams per tonne. Gold ounces are estimates of metal contained in tonnages and do not include allowances for processing losses. Contained (cont.) gold ounces are reported as troy ounces, rounded to the nearest 10,000.
6.Rounding of tonnes and contained metal content as required by reporting guidelines may result in apparent differences between tonnes, grade and contained metal content. Due to rounding, some cells may show a zero (“0”).
7.Totals may not sum due to rounding.
| | | | | | | | |
Date: February 2022 | | Page 1-13 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Pit design assumptions include haul road widths for two-way travel of 30 m, maximum ramp grades of 10% and minimum pit-bottom widths of 30 m in deep pits as a safety measure. For the last couple of benches to the pit bottom where good grades are located, the haul road widths are reduced to a 21 m one-way traffic to allow for maximum ore mining recovery.
1.14.2 Underground
Underground mining is currently conducted using conventional stoping methods, and conventional mechanized equipment. Underground mining is conducted by a contractor.
Mining levels are based on the mining method to be used, which varies by depth from surface. A set of twin spiral declines was developed off the existing main haulage decline. Level accesses were created off the decline at 20–25 m intervals, depending on mine elevation to intersect the ore zone. The ore drives have been driven to the extents of the defined mining corridor and stoping being retreated from the end of the orebody towards the accesses. These stopes are being mined top-down.
Mining was initially envisaged as long-hole open stoping mining method; however, an improved understanding of the geotechnical setting led to the selection of SLS in preference. A transition zone between mining methods at 450 m below surface was required to migrate the different stoping types. The mine will completely transition to the SLS mining method when the long-hole open stopes are complete, but currently the two mining methods are being used together.
Ground water inflows of approximately 40–45 L/s are predicted, and the current Subika dewatering system capacity is around 140 L/s.
The ventilation system for Subika includes refrigeration, primary and secondary fans and intake and return ventilation raises.
Trucks will be loaded from the level below the mining extraction level via the material placed in the ore pass. When stope mining is completed, the stopes will be backfilled with unconsolidated waste rock.
Underground infrastructure includes an electrical ring main, sumps, pumps and pump stations, cooling system, communications and telemetry system, mine control room, and two vehicle service bays.
1.15 Recovery Methods
The process plant design was based on a combination of metallurgical testwork, previous study designs and industry standard practices for handling combinations of fresh rock and saprolite, together with debottlenecking and optimization activities once the mill was operational. The design is conventional to the gold industry and has no novel parameters.
The process plant started operations in 2006 and was designed to treat 7.5 Mt/a using a blend of 27:73 oxide to primary ore. The plant was expanded in 2019 to treat an additional 3.0 Mt/a of primary ore. The planned throughput for the remaining LOM is projected to vary from 9.5–10.2 Mt/a (1,200–1,300 t/h), depending on the ore blend from the pits and underground operations.
The process consists of: primary crushing, semi-autogenous grind (SAG) milling, carbon-in-leach (CIL), Anglo American Research Laboratory method (AARL) elution circuit to strip gold
| | | | | | | | |
Date: February, 2022 | | Page 1-14 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
from loaded carbon, smelting to produce doré, and counter-current decantation to recover cyanide from CIL tailings prior to discharge to the tailings storage facility (TSF).
Power is sourced from the local grid. The main water sources for the process plant are from stored water in the mined out Apensu open pit and the TSF. Potable water is sourced from boreholes. Consumables used include grinding media, reagents, and high- and low-pressure air.
1.16 Infrastructure
The majority of the key infrastructure to support the Ahafo Operations mining activities envisaged in the LOM is in place. During the remainder of the LOM, a new waste rock storage facility (WRSF) for storage of waste from the Apensu area will be required, as will a second water treatment plant.
Personnel commute from surrounding settlements or live in purpose-built accommodations villages.
A stockpiling strategy is practiced to defer lower-grade ores to the end of the mine life. All stockpile inventories are calculated and reported monthly. Inventories are based on truck counts of material added to and removed from stockpiles, multiplied by truck tonnage factors.
WRSFs are sited on hillsides as bank fills or within shallow drainages as complete valley fills and were sited 60–100 m from pit crests. Lift heights are typically planned at 16–20 m and the overall slopes are designed at 3:1. The LOM plan assumes that only two WRSFs, at Subika East and Awonsu, will be active for the remainder of the mine life.
The TSF is operated as a zero-discharge facility; all water is returned to the process facility for reuse. The main embankment has been constructed in stages. The northern upstream embankment serves as a downstream dam for a water storage facility. Permitted capacities meet the required capacities for the present LOM. A raise to Cell 1 will allow operations to 2029; a raise to Cell 2, planned for 2030, will support the operations to the end of the LOM. The two TSF expansions, a Cell 1 that would be expanded to a maximum capacity of 190 Mt and a newly-constructed 50 Mt capacity Cell 2, and an associated 300 m water storage facility buffer require resettlement of a number of families within the facility footprints.
Water management infrastructure for mine operations includes pit runoff, surface water and groundwater management infrastructure. A reverse osmosis water treatment plant is operational.
Newmont Africa in Ghana receives power purchased from the Volta River Authority’s grid. Power is delivered to Ahafo via three GRIDCO 161 kV transmission lines into the Ahafo (Kenyasi) Substation. Each transmission line is capable of delivering power sufficient to satisfy Ahafo’s current peak startup power demand of about 35 MW, as the capacity of each of these lines is approximately 120 MW. Newmont has also installed 27 MW of emergency power generating capacity.
1.17 Markets and Contracts
Newmont has established contracts and buyers for the doré products from the Ahafo Operations, and has an internal marketing group that monitors markets for its key products.
| | | | | | | | |
Date: February, 2022 | | Page 1-15 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Together with public documents and analyst forecasts, these data support that there is a reasonable basis to assume that for the LOM plan, that the key products will be saleable at the assumed commodity pricing. The doré is not subject to product specification requirements.
Newmont uses a combination of historical and current contract pricing, contract negotiations, knowledge of its key markets from a long operations production record, short-term versus long-term price forecasts prepared by the company’s internal marketing group, public documents, and analyst forecasts when considering long-term commodity price forecasts. Higher metal prices are used for the mineral resource estimates to ensure the mineral reserves are a sub-set of, and not constrained by, the mineral resources, in accordance with industry-accepted practice.
Newmont’s doré is sold on the spot market, by marketing experts retained in-house by Newmont. The terms contained within the sales contracts are typical and consistent with standard industry practice and are similar to contracts for the supply of doré elsewhere in the world.
The largest in-place contracts other than for product sales cover items such as bulk commodities, operational and technical services, mining and process equipment, and administrative support services. Contracts are negotiated and renewed as needed. Contract terms are typical of similar contracts in Ghana.
1.18 Environmental, Permitting and Social Considerations
1.18.1 Environmental Studies and Monitoring
Baseline and supporting environmental studies were completed to assess both pre-existing and ongoing site environmental conditions, as well as to support decision-making processes during operations start-up. Characterization studies were completed for climate, air quality, hydrology and surface water quality, hydrogeology, flora, fauna, soils, agriculture and land use, and the socioeconomic environment.
Plans were developed and implemented to address aspects of operations such as waste and fugitive dust management, air quality, spill prevention and contingency planning, water management, and noise levels.
The primary environmental resource monitored at Ahafo is water – both surface water and groundwater. Other resource monitoring being conducted by Newmont includes fugitive dust, point source emission, meteorological parameters, noise and vibration, revegetation progress, surface water run-off quantity and quality, mine pit conditions, waste rock disposal, TSF decant water quantity and quality, and environmental geochemistry of ore, waste rock and tailings.
1.18.2 Closure and Reclamation Considerations
In 2003, Newmont developed a conceptual closure and reclamation plan for the Ahafo South Mine Project Environmental Impact Statement (EIS) in compliance with requirements of the Environmental Protection Agency (EPA). The EIS was approved by the EPA in April 2005. A Draft Reclamation Plan to begin the process of formalizing the conceptual plan presented in the EIS was undertaken later in 2005. Under EPA requirements, Newmont is required to provide updates to the reclamation plan as mine development proceeds. An updated Closure and
| | | | | | | | |
Date: February, 2022 | | Page 1-16 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Reclamation Plan was developed in 2019 that covers closure of the Subika Underground and ancillary infrastructure as well as the prior existing facilities. A Reclamation Security Agreement (RSA) between the EPA and Newmont was signed in April 2008 to outline the various objectives and targets as guidance for the plan.
The EPA requires a Reclamation Bond to be posted as part of any mine permitting process. The bond is required to provide financial surety against non-compliance under the approved Closure and Reclamation Plan and is required within six months after the start of operations. As part of the reclamation and security agreement (environmental bond) with the Ghanaian Government, Newmont has provided a cumulative (project to date) cash deposit of US$12.66 M.
The closure cost estimate used in the economic analysis in Chapter 19 is US$0.2 B.
1.18.3 Permitting
All major permits and approvals are either in place or Newmont expects to obtain them in the normal course of business. Where permits have specific terms, renewal applications are made of the relevant regulatory authority as required, prior to the end of the permit term.
1.18.4 Social Considerations, Plans, Negotiations and Agreements
Newmont developed a public consultation and disclosure plan (PCDP) for the Ahafo Operations using guidelines and policies developed by the International Finance Corporation (IFC). The IFC requires public consultation as an on-going process to be conducted during the construction and operational phases of any project.
Newmont has well-established relationships, issue management approaches, engagement forums, and a suite of integrated social impact and opportunity-aligned strategic investment partnerships. Newmont understands and accepts the importance of proactive community relations as an overriding principle in its day-to-day operations as well as future development planning. The company therefore structures its community relations activities to consider the concerns of the local people and endeavors to communicate and demonstrate its commitment in terms that can be best appreciated and understood to maintain the social license to operate.
1.19 Capital Cost Estimates
Capital cost estimates are at a minimum at a pre-feasibility level of confidence, having an accuracy level of ±25% and a contingency range not exceeding 15%.
Capital costs are based on recent prices or operating data. Capital costs include funding for infrastructure, pit dewatering, development drilling, and permitting as well as miscellaneous expenditures required to maintain production. Mobile equipment re-build/replacement schedules and fixed asset replacement and refurbishment schedules are included. Sustaining capital costs reflect current price trends.
The overall capital cost estimate for the LOM is US$0.5 B, as summarized in Table 1-4.
| | | | | | | | |
Date: February, 2022 | | Page 1-17 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
1.20 Operating Cost Estimates
Operating cost estimates are at a minimum at a pre-feasibility level of confidence, having an accuracy level of ±25% and a contingency range not exceeding 15%.
Operating costs are based on actual costs seen during operations and are projected through the LOM plan. Historical costs are used as the basis for operating cost forecasts for supplies and services unless there are new contract terms for these items. Labor and energy costs are based on budgeted rates applied to headcounts and energy consumption estimates.
Operating costs for the LOM are estimated at US$3.5 B, as summarized in Table 1-5.
Table 1-4: Capital Cost Estimate
| | | | | | | | |
Area | Unit | Value |
Mining, open pit | US$ B | 0.2 |
Mining, underground | US$ B | 0.2 |
Process | US$ B | 0.1 |
Total | US$ B | 0.5 |
Note: numbers have been rounded; totals may not sum due to rounding.
Table 1-5: Operating Cost Estimate
| | | | | | | | |
Area | Unit | Value |
Mining, open pit | US$ B | 0.6 |
Mining, underground | US$ B | 1.2 |
Process | US$ B | 1.2 |
G&A | US$ B | 0.5 |
Total | US$ B | 3.5 |
Note: numbers have been rounded; totals may not sum due to rounding.
The estimated LOM open pit mining cost is US$2.57/t and the underground mining cost is US$52.27/t. Base processing costs are estimated at US$11.84 /t. In addition, total G&A costs are estimated at US$5.15/t.
1.21 Economic Analysis
1.21.1 Economic Analysis
The financial model that supports the mineral reserve declaration is a standalone model that calculates annual cash flows based on scheduled ore production, assumed processing recoveries, metal sale prices and Gh$/US$ exchange rate, projected operating and capital costs and estimated taxes.
The financial analysis is based on an after-tax discount rate of 8%. All costs and prices are in unescalated “real” dollars. The currency used to document the cash flow is US$.
| | | | | | | | |
Date: February, 2022 | | Page 1-18 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
All costs are based on the 2022 budget. Revenue is calculated from the recoverable metals and long-term metal price and exchange rate forecasts.
Taxes are based on Newmont’s existing agreement with the Government of Ghana.
The economic analysis assumes constant prices with no inflationary adjustments.
The NPV8% is $1.2 B. As the cashflows are based on existing operations where all costs are considered sunk to 1 January 2022, considerations of payback and internal rate of return are not relevant.
A summary of the financial results is provided in Table 1-6. In this table, EBITDA = earnings before interest, taxes, depreciation and amortization. The active mining operation ceases in 2032; however, closure costs are estimated to 2036.
1.21.2 Sensitivity Analysis
The sensitivity of the Project to changes in metal prices, exchange rate, sustaining capital costs and operating cost assumptions was tested using a range of 25% above and below the base case values Figure 1-1).
The Project is most sensitive to metal price changes, less sensitive to changes in operating costs, and least sensitive to changes in capital costs. The sensitivity to gold grade mirrors the sensitivity to the gold price and is not shown.
1.22 Risks and Opportunities
Factors that may affect the mineral resource and mineral reserve estimates are summarized in Chapter 1.11.3 and Chapter 1.12.3.
1.22.1 Risks
The risks associated with the Ahafo Operations are generally those expected with open pit and underground mining operations and include the accuracy of the resource model, unexpected geological features that cause geotechnical issues, and/or operational impacts.
Other risks noted include:
•The mineral reserve estimates are sensitive to metal prices. Lower metal prices than forecast in the LOM plan may require revisions to the mine plan, with impacts to the mineral reserve estimates and the economic analysis that supports the mineral reserve estimates;
•Labor cost increases or productivity decreases could also impact the stated mineral reserves and mineral resources;
•Geotechnical and hydrological assumptions used in mine planning are based on historical performance, and to date historical performance has been a reasonable predictor of current conditions. Any changes to the geotechnical and hydrological assumptions could affect mine planning, affect capital cost estimates if any major rehabilitation is required due to a geotechnical or hydrological event, affect operating costs due to mitigation measures that may need to be imposed, and impact the economic analysis that supports the mineral reserve estimates;
| | | | | | | | |
Date: February, 2022 | | Page 1-19 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
•Expectations as to the performance of the Subika underground mining method;
•Proposed community resettlement as part of the TSF planning for the LOM. There is a risk that this can be achieved with stakeholder approval and within the timelines anticipated and budgets allocated;
•Galamsey (artisanal mining) activity can impact mine safety and operations;
•Changes in climate could result in drought and associated potential water shortages that could impact operating costs and ability to operate;
•Political risk from challenges to mining licenses and/or Newmont’s right to operate.
Table 1-6: Cashflow Summary Table
| | | | | | | | |
Item | Unit | Value |
Metal prices |
Gold | US$/oz | 1,200 |
Mined ore |
Tonnage | M tonnes | 102 |
Gold grade | g/t | 1.9 |
Gold ounces | Moz | 6.1 |
Capital costs | US$B | 0.5 |
Costs applicable to sales | US$B | 4.2 |
Discount rate | % | 8 |
Exchange rate | United States dollar:Ghanaian cedi (USD:GHS) | 5.75 |
Free cash flow | US$B | 1.5 |
Net present value | US$B | 1.2 |
Note: Numbers have been rounded; totals may not sum due to rounding. Table 1-6 contains “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, which are intended to be covered by the safe harbor created by such sections and other applicable laws. Please refer to the note regarding forward-looking information at the front of the Report. The cash flow is only intended to demonstrate the financial viability of the Project. Investors are cautioned that the above is based upon certain assumptions which may differ from Newmont’s long-term outlook or actual financial results, including, but not limited to commodity prices, escalation assumptions and other technical inputs. For example, Table 1-6 uses the price assumptions stated in the table, including a gold commodity price assumption of US$1,200/oz, which varies significantly from current gold prices and the assumptions that Newmont uses for its long-term guidance. Please be reminded that significant variation of metal prices, costs and other key assumptions may require modifications to mine plans, models, and prospects.
| | | | | | | | |
Date: February, 2022 | | Page 1-20 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Figure 1-1: NPV Sensitivity
Note: Figure prepared by Newmont, 2021. FCF = free cashflow; op cost = operating cost; cap cost = capital cost; NPV = net present value.
1.22.2 Opportunities
Opportunities include:
•Conversion of some or all of the measured and indicated mineral resources currently reported exclusive of mineral reserves to mineral reserves, with appropriate supporting studies;
•Upgrade of some or all of the inferred mineral resources to higher-confidence categories, such that such better-confidence material could be used in mineral reserve estimation;
•Higher metal prices than forecast could present upside sales opportunities and potentially an increase in predicted Project economics;
•Potential for new underground operations proximal to the current mineral resource and mineral reserve estimates, with the support of additional studies.
1.23 Conclusions
Under the assumptions presented in this Report, the Ahafo Operations have a positive cash flow, and mineral reserve estimates can be supported.
1.24 Recommendations
As the Ahafo Operations are operating mines, the QP has no material recommendations to make.
| | | | | | | | |
Date: February, 2022 | | Page 1-21 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
2.0 INTRODUCTION
2.1 Registrant
This technical report summary (the Report) was prepared for Newmont Corporation (Newmont) on the Ahafo Operations (Ahafo Operations or the Project) located in the Republic of Ghana (Ghana). The location of the operations is shown in Figure 2-1.
Newmont has three subsidiaries registered under the laws of Ghana: Newmont Ghana Gold Ltd. (NGGL), Newmont Golden Ridge Ltd. (NGRL) and Moydow Limited (Moydow). For the purposes of this Report, the name Newmont is used interchangeably for the subsidiary and parent company.
2.2 Terms of Reference
2.2.1 Report Purpose
The Report was prepared to be attached as an exhibit to support mineral property disclosure, including mineral resource and mineral reserve estimates, for the Ahafo Operations in Newmont’s Form 10-K for the year ending December 31, 2021.
Mineral resources are reported for Apensu, Awonsu and Subika open pits, and Subika and Apensu underground.
Mineral reserves are reported for Subika and Awonsu open pits and Subika underground. Mineral reserves are also estimated for material in stockpiles.
2.2.2 Terms of Reference
The Ahafo Operations consist of two open pit operations at Awonsu and Subika, and underground operations at Subika.
Mining commenced in 2006 from open pit sources. Figure 2-2 shows the location of the current and mined-out open pits, and development prospects.
Unless otherwise indicated, all financial values are reported in United States (US) currency (US$). Business plans for 2020, 2021, and 2022 are referred to as BP2020, BP2021, and BP2022 respectively throughout this Report.
Unless otherwise indicated, the metric system is used in this Report.
Mineral resources and mineral reserves are reported using the definitions in Regulation S–K 1300 (SK1300), under Item 1300.
The Report uses US English.
The Report contains forward-looking information; refer to the note regarding forward-looking information at the front of the Report.
| | | | | | | | |
Date: February, 2022 | | Page 2-1 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Figure 2-1: Project Location Plan
| | | | | | | | |
Date: February, 2022 | | Page 2-2 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Figure 2-2: Mining Operations Layout Plan
Note: Figure prepared by Newmont, 2021.
2.3 Qualified Persons
The following Newmont employee serves as the Qualified Person (QP) for the Report:
•Mr. Donald Doe, RM SME., Group Executive, Reserves, Newmont.
Mr. Doe is responsible for all Report Chapters.
2.4 Site Visits and Scope of Personal Inspection
Mr. Doe visited the Ahafo Operations on many occasions, most recently from November 11–15, 2019.
During this site visit, Mr. Doe inspected the operating open pits, and examined the underground operations. He visited the core shack and inspected drill core. Mr. Doe also viewed the Ahafo process plant and associated general site infrastructure, including the current tailings storage facility (TSF) operations.
| | | | | | | | |
Date: February, 2022 | | Page 2-3 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
While on site, he typically discusses aspects of the operation with site-based staff. These discussions include the overall approach to the mine plan, anticipated mining conditions, selection of the production target and potential options for improvement, as well as reconciliation study results. Other areas of discussion include plant operation and recovery forecasts and plans for the expanded TSF. Mr. Doe reviews capital and operating forecasts with site staff.
Mr. Doe also reviews Newmont’s processes and internal controls on those processes at the mine site with operational staff on the work flow for determining mineral resource and mineral reserve estimates, mineral process performance, production forecasts, mining costs, and waste management.
2.5 Report Date
Information in the Report is current as at December 31, 2021.
2.6 Information Sources and References
The reports and documents listed in Chapter 24 and Chapter 25 of this Report were used to support Report preparation.
2.7 Previous Technical Report Summaries
Newmont has not previously filed a technical report summary on the Project.
| | | | | | | | |
Date: February, 2022 | | Page 2-4 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
3.0 PROPERTY DESCRIPTION
3.1 Introduction
The Ahafo Operations are located in western Ghana near the towns of Kenyasi and Ntotroso in the Ahafo Region, about 290 km northwest of Accra. The operations are 107 km northwest of Kumasi, and 40 km south of the regional capital of Sunyani.
The Ahafo Operations are centered at about 2º20’59” west longitude, and 7º02’13” north latitude. The centroid locations, in latitude/longitude of the deposits that have mineral resource estimates are:
•Subika: 2°21'49" west longitude and 6°59'51" north latitude;
•Apensu: 2°21'44" west longitude and 7°01'17" north latitude;
•Awonsu: 2°20'58" west longitude and 7°02'15" north latitude;
•Amoma: 2°18'15" west longitude and 7°05'18" north latitude.
3.2 Property and Title in Ghana
3.2.1 Mineral Title
Mineral exploration and mining are administered in Ghana under the Minerals and Mining Act, 2006 (Act 703) and relevant Regulations that came into force in June 2012. These are Minerals and Mining (General) Regulations, Minerals and Mining (Licensing) Regulations, Minerals and Mining (Support Services) Regulations, Minerals and Mining (Compensation and Resettlement) Regulations, Minerals and Mining (Explosives) Regulations and the Minerals and Mining (Health, Safety and Technical) Regulations. The State is the owner of all minerals occurring in their natural state within Ghana's land and territorial sea, including its exclusive economic zone but is vested in the President on behalf of and in trust for the people of Ghana.
Three types of mineral rights can be granted after the applicant’s fiscal and technical ability to perform effective exploration or mining is verified: reconnaissance and prospecting licenses, and mining leases (Table 3-1).
3.2.2 Surface Rights
A mineral right holder is required to exercise their rights so that impacts on the interests of any lawful owner or occupier of the land are minimized. The lawful owner or occupier retains the right to graze livestock and cultivate the land in so far as such activities do not interfere with the mineral operations. The owner or occupier may apply to the mineral right holder for compensation for any disturbance of their rights, for damage to buildings, improvements, livestock, crops, or trees. Assessment of compensation eligibility and amount payable, in practice, requires extensive stakeholder engagement including affected landowners, the Land Valuation Division and cooperation of traditional authorities. Lawful owners or occupiers of land must obtain permission from a mining company to erect any building or structure on the land in an area of the lease declared a Mining Area by the mineral right holder.
| | | | | | | | |
Date: February, 2022 | | Page 3-1 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Table 3-1: Types of Mineral Rights
| | | | | |
Mineral Right Name | Comment |
Reconnaissance License | Granted for a maximum area of 1,050 km2 in aggregate. Allows for non-intrusive reconnaissance exploration such as remote sensing, surface geology and geochemical sampling (no excavation or drilling) and confers exclusive rights to the holder to undertake reconnaissance for the specific granted mineral(s) for a year. License is renewable for another 12 months provided that notification of the intention to extend the term of the license is provided not later than 90 days before the expiration of the initial term of the license. Renewals must be supported by a professional technical terminal report. |
Prospecting License | Confers exclusive rights to the holder to prospect for granted mineral(s). Licenses may not exceed 157.5 km2 in aggregate. Granted for an initial period not exceeding three years with the ability to renew for an additional period of not more than three years. Notification of intention to renew the term of the license must be received not later than 90 days before the expiration of the initial term of the license. Renewals must be supported by a professional terminal report. License holder is required to relinquish not less than half of the original license area after the expiration of the first three-year term |
Mining Lease | Required to commence mining operations. Requires the applicant to submit a feasibility report in accordance with the Minerals Commission’s guidelines, stating how the planned mining operation is to be carried out. The lease area is limited to a maximum area of 63 km2; however, an enlargement of the lease area may be granted by the Minister responsible for mines if satisfied on reasonable grounds that the additional area is required for the holder’s operations. Granted for a maximum 30-year term, and renewable thereafter upon negotiated terms. |
Although some parts of the Ghanaian land law are derived from English common law and equity, the fundamental principles of land ownership are distinct from that of the English law of real property. The basis of English law of real property is that the Crown owns all land; however, in Ghana land is owned by various Stools, families, or clans (the owners). The Government of Ghana may only hold land by acquisition from these traditional owners, if necessary, in the interest of defense, public safety, public order, public morality, public health, town and country planning or the development or utilization of property in such a manner as to promote the public benefit and fair and adequate compensation is paid.
Traditionally, the owners of non-vested Stool lands enjoy much wider rights than is the case for vested lands, but in practice traditional authorities and privileges are similar to those due to the Crown and generally result in a similar outcome. The ability of the traditional Stool owners to exercise exclusive rights depends on ancestral links and the individuals’ standing within the community.
Land-use rights vary between landlords and tenants. Generally, a landlord is a property holder who has exclusive rights to use or to dispose of use rights to land. Land use rights are typically acquired from traditional rulers and family heads or by inheritance and are disposed otherwise by contracts for sharecropping or lease.
A given householder may be a landlord of one farm field, a sharecropper on another and a caretaker on a third.
Largely, with respect to land within the area affected, the original (traditional) owners retain the surface rights, as in the Asutifi North District where the Ahafo Operations are located, unless their rights are curtailed by Newmont being awarded a mining lease and paying the appropriate compensation. The grant of a mining lease by the Government of Ghana may curtail the
| | | | | | | | |
Date: February, 2022 | | Page 3-2 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
interest of traditional owners. Thus, the lease agreement requires the payment of revenue to the affected owner in the form of ground rent which for traditional owners are managed by the Office of the Administrator of Stool Lands for the benefit of the traditional owners and the District within which the mineral rights sits.
3.2.3 Royalties
The Government of Ghana levies royalties on mining projects, including the Ahafo Operations. These are discussed in Chapter 3.9.
3.3 Ownership
3.3.1 Ownership History
In 1993, a joint venture (JV) agreement was signed between the French governmental organization Bureau Recherché Geologiques et Minieres (BRGM) and the South African company Gencor Ltd (Gencor) to explore in Ghana and Cote d’Ivoire. In 1994, the JV signed an option agreement with Ghanaian company Minconsult over the Yamfo license and formed the Centenary Gold Mining Company (41% BRGM, 41% Gencor, 8% Minconsult, and 10% Ghanaian Government). In the same year, La Source Compagnie Miniere SAS (La Source) was established with Normandy Mining Limited (Normandy) holding 60%, and BRGM 40%. La Source took over BRGM’s West African exploration and mining assets. In 1998, La Source consolidated its position when it acquired the former Gencor and Minconsult interests in Yamfo. In 2000, the name Centenary Gold Mining Company Limited was changed to Normandy Ghana Gold Limited (NGGL).
The Ntotroso license area (formerly the Rank Mining Concession) was acquired in 1997 when La Source purchased a 40% share in Rank Mining Company Limited (Rank). Rank held a 40% interest in the Rank JV Farm-In Agreement with Moydow Mines International Inc (Moydow; 60% interest), that covered the Ntotroso concessions. La Source increased its holding in Rank, and thus the JV, to 50% in 2001, by funding exploration and development in accordance with the agreement.
Newmont acquired Normandy and the Ghanaian projects in early 2002. In December 2003, Newmont acquired the remaining 50% interest in Rank. The same month, Newmont and the Government of Ghana signed an investment agreement guaranteeing Newmont certain financial and operating rights over a period of 30 years for its projects in Ghana.
Newmont renamed the Sefwi and Ntotroso projects to Ahafo, and then separated the area into two sections, Ahafo North and Ahafo South, based on location north or south of the Shelterbelt Forest Reserve. Ahafo North will be a completely stand-alone operation, with no major shared infrastructure with Ahafo South. This Report focuses on Ahafo South.
3.3.2 Current Ownership
The Project is held through Newmont Ghana Gold Ltd., an indirectly-wholly owned Newmont subsidiary.
| | | | | | | | |
Date: February, 2022 | | Page 3-3 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
3.4 Mineral Title
Newmont currently holds three mining licenses, and nine prospecting licenses that in total cover an area of 951.93 km2:
•The mining leases are current until 2031 and can be renewed by negotiation. The total area held under mining licenses is approximately 548.73 km2;
•The prospecting licenses are valid and are in good standing. The total area covered by prospecting licenses is about 403.20 km2.
The Ahafo mining lease is separated into two areas, where Ahafo South is in Area A, and Ahafo North in Area B (Figure 3-1). Ahafo North is planned to be developed as a stand-alone operation, will not share infrastructure or facilities with Ahafo South, and is not included in this Report. The licenses within the Ahafo South (Ahafo Operations) area are shown in Figure 3-2. A summary of the mineral tenure that makes up the Ahafo Operations is provided in Table 3-2.
The current mine take area is approximately 53 km2, and represents the area that has been fully compensated. Approximately 43 km2 has not been fully compensated (e.g., payment would be necessary to move people from their land).
Under Ghanaian law, only mining leases and prospecting licenses require surveys; reconnaissance license types are delineated by latitude/longitude co-ordinates. All of the Ahafo mining leases were surveyed by Newmont staff, using global positioning system (GPS) readings and identifiable benchmarks on topographic maps to locate the boundary pillars on the ground from site plans.
A number of payments are required to keep the licenses/leases in good standing, and include:
•Annual rental: payable by January of each year;
•Annual prospecting and mining permit payments: payable by January of each year.
All required payments have been made as they fall due.
3.5 Surface Rights
Newmont was granted a Plan of Operations (PoO) for the Ahafo Operations, and may use whatever land is necessary for its operations but must respect the surface rights of other land users in relation to access and loss of crops, timber, or structures. Extensive title searches were conducted over the mining lease areas and no titles exist that would categorically exclude Newmont’s operations on the Project lands. Newmont’s indenture for surface lands will run concurrently with the life of the operations, but will extend for no more than 50 years.
| | | | | | | | |
Date: February, 2022 | | Page 3-4 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Figure 3-1: Ahafo District Mineral Tenure Map
Note: Figure prepared by Newmont, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 3-5 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Figure 3-2: Ahafo Operations Mineral Licenses Map
Note: Figure prepared by Newmont, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 3-6 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Table 3-2: Mineral Tenure Summary Table
| | | | | | | | | | | | | | | | | |
Concession | License Type | License Number | Size (km2) | Grant Date | Expiry Date |
Ahafo (Area A) | Mining Lease | LVB 7523/2001 | 272.58 | 1/22/2001 | 6/12/2031 |
Ahafo (Area B) | Mining Lease | LVB 7523/2001 | 187.53 | 1/22/2001 | 6/12/2031 |
Bonkori | Prospecting | PL 7/123 | 1.89 | 6/4/2019 | 6/3/2022 |
Dekyem | Prospecting | PL7/82; LVB 3080/05 | 36.75 | 6/17/2019 | 6/16/2022 |
Dekyem South | Prospecting | PL7/122 | 42.63 | 6/30/2020 | 6/29/2023 |
Goa | Mining Lease | 1809/2005; LVB13908/05 | 11.97 | 10/7/2001 | 10/6/2031 |
Goa | Prospecting | RL 7/36; LVB 3082/05 | 92.19 | 6/10/2019 | 6/9/2022 |
Goaso | Prospecting | PL 7/31 | 29.61 | 1/23/2019 | 1/22/2022 |
Mampehia | Prospecting | PL (7/85); LVB 5014/2006 | 36.12 | 7/18/2019 | 7/17/2022 |
Mankraho | Prospecting | PL 7/87; LVB 10714/03 | 103.53 | 6/4/2019 | 6/3/2022 |
Ntotroso (Rank Mining) | Mining Lease | LVB 7524/2001 | 76.65 | 6/13/2001 | 6/12/2031 |
Nyameakyede (Akyerensua) | Prospecting | RL 7/54; LVB 26942/07 | 25.41 | 6/4/2019 | 6/3/2022 |
Tanoso | Prospecting | PL 7/84 | 35.07 | 1/23/2019 | 1/22/2022 |
Note: All dates in month/day/year format.
The Ahafo operations cover an area of approximately 137,000 acres (55,000 hectares) for the mining lease concession with current mine take area of approximately 13,200 acres (5,300 hectares) that has been fully compensated and approximately 10,700 acres (4,300 hectares) of mining area that has not been fully compensated (e.g., payment would be necessary to move people from their land).
3.6 Water Rights
Newmont holds permits to allow abstraction of groundwater, surface water, and water from the Tano River and discharge of water from the water storage facility (see Chapter 17 for additional details).
3.7 Forest Reserves
Areas of productive Forest Reserves were designated in the vicinity of the Ahafo Operations. These areas include the Bosumkese Forest Reserve and the Amoma Shelterbelt Forest Reserve (refer to Figure 3-1).
Potential impacts on the Forest Reserves include roads, powerline access, and general proximity of mining operations to the Forest Reserve areas.
3.8 Agreements
3.8.1 Investment Agreement
The Revised Investment Agreement (the Agreement) between Newmont and the Government of Ghana defines and fixes, in specific terms, the effective corporate tax and royalty burden the Project (including Ahafo South and Ahafo North) will carry during operations. The Agreement
| | | | | | | | |
Date: February, 2022 | | Page 3-7 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
establishes a fixed fiscal and legal regime, including sliding-scale royalty and tax rates for the duration of the Agreement’s stability period.
The Agreement was re-negotiated and ratified in December, 2015. Under the Agreement stability period, which now extends until the end of 2025, the tax rate will remain at 32.5%. After the cessation of the stability period, the tax rate will increase to 35%. During the stability period, Newmont will pay gross royalties on gold doré production in accordance with a sliding scale of 3–5%, tied to the gold price. After the Agreement ends, the royalty rate will be fixed at 5%.
An additional 0.6% is payable as a special fee for gold doré production from designated Forest Reserves (see discussion in Chapter 3.7).
3.8.2 Government of Ghana Free-Carried Interest
The Government of Ghana has a 10% free-carried interest in the Ahafo Operations. Newmont pays the Government of Ghana a ninth of the dividend declared to Newmont shareholders. Since December 2015, Newmont has been obligated to pay 0.6% of the operational revenue if the gold price averages US$1,300/oz or higher, as an advance dividend against the one-ninth share.
3.9 Royalties
A net smelter return (NSR) royalty of 2.0% is payable on all ounces produced from the Rank (formerly Ntotroso) concession. The royalty is paid to Franco-Nevada Corporation (Franco-Nevada), which acquired the royalty for US$58 M in November 2009. The majority of the Subika deposit, the northern portion of the Awonsu deposit, and the southern tip of the Amoma deposit fall within the Rank mining lease boundary.
Royalties in forest reserves are currently not applicable for the Ahafo Operations.
3.10 Encumbrances
There are no known encumbrances.
3.11 Permitting
Permitting and permitting conditions are discussed in Chapter 17.9 of this Report. There are no relevant permitting timelines that apply; the operations as envisaged in the LOM plan are either fully permitted, or the processes to obtain permits are well understood and similar permits have been granted to the operations in the past, such as tailings storage facility (TSF) raises.
There are no current material violations or fines, as imposed in the mining regulatory context of the Mine Safety and Health Administration (MSHA) in the United States, that apply to the Ahafo Operations.
| | | | | | | | |
Date: February, 2022 | | Page 3-8 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
3.12 Significant Factors and Risks That May Affect Access, Title or Work Programs
Newmont’s Ahafo concession started in 2008 at Kenyase (Ahafo South) and spread to the Ahafo North communities. However, Newmont embarked on a series of facilitated interventions in collaboration with the communities and National Security to drastically discourage illegal mining. Notwithstanding this, the activity intermittently continued until the Government of Ghana implemented an ‘operations-stop-galamsey’ policy which has brought illegal mining to a temporary halt both in the Newmont concessions and elsewhere in Ghana.
The surge in galamsey (illegal mining) activities in the last few years within the mining area has been identified as a major risk to Newmont’s short-, medium- and long-term sustainability and has the potential to drive community conflict due to encroachment on farmlands and its attendant social vices. Newmont has seen increases in violent confrontations between illegal galamsey operatives and public/private security and use of illegal explosives within the Mine Take area, invasion of active mining pits and run-of-mine (ROM) pad, among others.
Newmont is implementing the Ahafo Dome Project that involves increased aerial surveillance, coupled with a dedicated Mobile Response Unit consisting of several teams within the area that has been designated as having restricted access (mine take area). Measures that include immediate and responsible removal of galamsey operators within the mine take can be conducted per an established protocol with the support of security and the social and environmental departments. Such measures, performed in collaboration with the relevant government, public security officials and traditional authorities, has resulted in significant reduction in the numbers in key areas that pose a threat to the mine.
Newmont continues to pursue implementation of the livelihood approach under Newmont’s Regional galamsey strategy which complements galamsey operative removals from the mining areas. This involves identification of community workers in the galamsey value chain who are interested in pursuing alternative livelihood opportunities.
Despite the above, the threat of illegal mining still exists, except that frequent monitoring as mentioned wards off such incursions.
To the extent known to QP, there are no other known significant factors and risks that may affect access, title, or the right or ability to perform work on the properties that comprise the Ahafo Operations that are not discussed in this Report.
| | | | | | | | |
Date: February, 2022 | | Page 3-9 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
4.0 ACCESSIBILITY, CLIMATE, LOCAL RESOURCES, INFRASTRUCTURE AND PHYSIOGRAPHY
4.1 Physiography
The Ahafo Operations area comprises low rounded hills with elevations ranging from 110 m to 540 masl. The upper part of the Tano River basin is drained by a number of seasonal streams that are tributaries of the Tano River. Two streams, the Subri and the Awonsu, drain from the Project area to the Tano River.
The Project shares a boundary with the Bosumkese Forest Reserve, and the Amoma Shelterbelt Forest Reserve bisects the Ahafo mining lease.
The Ahafo Operations area consists primarily of subsistence farms with small-scale commercial farming intermingled with areas of forest regrowth and remnants of secondary forest. The major agricultural land uses are cocoa, food crops, and rice farming. South of the Bosumkese Forest Reserve, cocoa farming is the major activity, while to the north maize farming dominates.
4.2 Accessibility
Road access to the Ahafo Operations is via Route 6, an asphalt-paved road from Accra to the Tepa Junction via Kumasi in the direction of Sunyani, a distance of approximately 300 km. From Tepa Junction, an asphalt-paved road leads west for 39 km through the villages of Tepa and Akyerensua to Hwidiem. A paved road then leads northwest for 8 km to the village of Kenyasi. Newmont constructed a bypass north of Kenyasi to facilitate supply deliveries, and route traffic around the town for safety reasons.
The operating mines are all accessible on mine roads from the plant site.
4.3 Climate
The Project area falls within the wet semi-equatorial climatic zone of Ghana that is characterized by an annual double maxima rainfall pattern, occurring in the months of May to July and from September to October.
Mean annual rainfall for the Project area is between 1,354–1,400 mm. Typically, minimal rainfall is experienced from December to the end of February, with January as the driest month. Mean monthly temperatures within the area range from 23.9–28.4°C.
The Ahafo Operations are conducted year-round.
4.4 Infrastructure
The Project lies within two Administrative Districts, Tano North in the north and Asutifi North in the south. Each district has its own central government-based District Council as well as a number of Traditional Government Paramount Chieftaincies.
Sunyani is a major regional center and is the source of supplies and fuel. There are adequate schools, medical services and businesses to support the work force. A skilled and semi-skilled
| | | | | | | | |
Date: February, 2022 | | Page 4-1 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
mining workforce has been established in the region as a result of on-going mining activities. Workers live in the surrounding communities.
The Ahafo Operations currently have all infrastructure in place to support mining and processing activities (see also discussions in Chapter 13, Chapter 14, and Chapter 15 of this Report). These Report chapters also discuss water sources, electricity, personnel, and supplies.
| | | | | | | | |
Date: February, 2022 | | Page 4-2 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
5.0 HISTORY
The exploration and development history of the Ahafo Operations is summarized in Table 5-1. Two open pits, Apensu and Amoma, were mined out in 2016 and 2017 respectively.
Table 5-1: Exploration and Development History Summary Table
| | | | | | | | |
Year | Company | Note |
1989–1991 | Ghanaian–German mineral prospecting project | Identified a gold-in-soil anomaly that had a strike-length of 1.2 km |
1992 | Minconsult | Soil sampling on 50 m x 400 m grid |
1993–1995 | BRGM and Gencor/Centenary Mining Company | Stream sediment sampling, soil sampling, trenching, pitting, rotary air blast (RAB), reverse circulation (RC) and core drilling and an initial mineral resource estimate |
1996 | BRGM and Gencor/Centenary Mining Company | Scoping study evaluated the Teekyere West, Yamfo Central and Line 10 deposits (now within the Ahafo North area) |
Moydow Mines International Inc. (Moydow) | Identified eight major gold-in-soil anomalies in the Ntotroso Prospecting License (Rank Concession) |
1997 | BRGM and Gencor/Centenary Mining Company | Feasibility study based on an updated resource estimate commenced but halted due to falling commodity prices |
Moydow | RC drilling program completed on Areas A (now the Apensu–Awonsu area), C (now Amoma) and E (now Subika). Resource estimates for Areas A and C |
1998 | Normandy | BRGM, La Source and Normandy joint venture dissolved; Normandy takes over operations. Commenced major drill program |
1999 | Completed pre-feasibility study |
2000 | Normandy | Completed feasibility study |
Moydow | Resource estimate at Subika. Rank Development and Production Agreement signed by La Source and Moydow, to allow for treatment of mineralization from the Rank Concession deposits through a common plant. Feasibility study on the Subika and Area A deposits |
2002 | Newmont | Merges with Normandy, renames area to Ahafo |
2003 | Feasibility study on Ahafo North and South deposits. Purchases Moydow properties, Moydow retains 2% NSR royalty, covering covers 78 km2 of the southeastern end of the Project area |
2006 | Constructed process plant. Commenced open pit mining at the Apensu deposit |
2008 | Identified Subika underground |
2009 | Franco Nevada | Franco Nevada purchases Moydow 2% NSR royalty |
2012–2013 | Newmont | Underground trial mining program at Subika |
2014 | Identified Apensu Deeps area |
2016 | Extension of mineralization to the north of Apensu identified. Apensu open pit mined out |
2017 | Amoma open pit mined out |
2018 | Commercial production from Subika underground |
2019 | Initiated studies to change mining method at Subika underground to sub-level shrinkage stoping |
| | | | | | | | |
Date: February, 2022 | | Page 5-1 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
6.0 GEOLOGICAL SETTING, MINERALIZATION, AND DEPOSIT
6.1 Deposit Type
The deposits that comprise the Ahafo Operations are considered to be examples of orogenic gold deposits. Such deposits have many synonyms including mesothermal, mesozonal and hypozonal deposits, lode gold, shear zone-related quartz–carbonate deposits, or gold-only deposits (Groves et al., 1998).
Orogenic gold deposits occur in variably deformed metamorphic terranes formed during Middle Archean to younger Precambrian, and continuously throughout the Phanerozoic. The host geological environments are typically volcano–plutonic or clastic sedimentary terranes, but gold deposits can be hosted by any rock type. There is a consistent spatial and temporal association with granitoids of a variety of compositions. Host rocks are metamorphosed to greenschist facies, but locally can achieve amphibolite or granulite facies conditions.
Gold deposition occurs adjacent to first-order, deep-crustal fault zones. Economic mineralization typically formed as vein fill of second- and third-order shears and faults, particularly at jogs or changes in strike along the crustal fault zones. Mineralization styles vary from stockworks and breccias in shallow, brittle regimes, through laminated crack-seal veins and sigmoidal vein arrays in brittle-ductile crustal regions, to replacement- and disseminated-type orebodies in deeper, ductile environments.
Quartz is the primary constituent of veins, with lesser carbonate and sulfide minerals. Sulfide minerals can include pyrite, pyrrhotite, chalcopyrite, galena, sphalerite, and arsenopyrite. Gold is usually associated with sulfide minerals, but native gold can occur.
6.2 Regional Geology
The West African craton is sub-divided into two domains, the Archean Reguibat Shield, in Mauritania to the north, and the Paleo-Proterozoic Man Shield in the south between Ghana and Senegal. The Man Shield is divided into two sectors, a western portion consisting of rocks of Liberian age (3.0–2.5 Ga) and an eastern terrain underlain by Paleoproterozoic Birimian rocks.
The Birimian rocks consist of five evenly-spaced tholeiitic to acidic composition volcanic belts trending northeast–southwest. Three granite successions intrude the Birimian rocks. Basins between the volcanic belts are filled by predominantly turbiditic sedimentary rocks. The transition zones between the volcanic rocks and the sedimentary rocks are filled with chemical sedimentary rocks. All the units are contemporaneous and may be laterally equivalent facies.
The Ahafo deposits are located in the Sefwi Belt, one of the five Birimian volcanic belts. Volcanic rocks in the belt are mainly basaltic and are metamorphosed to varying degrees from lower greenschist to lower amphibolite facies with elongate hornblende-bearing granite plutons of the Dixcove suite. The sedimentary succession consists mainly of fine to medium-grained lithologies (argillites and wackes) with variable amounts of volcaniclastic material. Cape Coast-type two-mica granites intrude the metasedimentary rocks.
Faults and associated structures display a complex history of movement including thrust faulting and shearing with both normal and strike–slip motion and have played a major role in
| | | | | | | | |
Date: February, 2022 | | Page 6-1 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
emplacement of mesothermal gold mineralization. Regional structure is controlled by the Kenyasi Thrust Fault, a northeast to southwest trending regional thrust complex.
6.3 Local Geology
The Ahafo Operations area includes four deposits localized along two northeast-striking structural zones (Figure 6-1). A stratigraphic column for the district is provided in Figure 6-2.
Discrete mineralization styles are recognized within the Ahafo Operations area, which are termed Kenyasi-style (shear-zone hosted) and Subika-style (granite hosted).
Mineralization in Kenyasi-style deposits is associated with mixed (meta)-pelitic sedimentary rocks and (meta)-mafic volcanic units along the footwall of the Kenyasi Thrust Fault. Dixcove Suite granitoids form the hanging wall to the thrust, and appear to be overthrust onto the volcano–sedimentary sequence. Multiple thrust fault duplexes developed along the thrust contact between the granitoids in the hanging wall and volcano/sedimentary rocks in the footwall and are favorable sites for gold deposition.
In Subika-style deposits, mineralization is hosted in Dixcove Suite granitoids. The granitoids are cut by multiple mylonite zones that occur as imbricate thrusts and vary in thickness from <1 m to as much as 10 m. Zones of brittle fracturing and dilatant breccias are commonly developed over the mylonite zones and are favorable loci for gold deposition.
6.4 Property Geology
6.4.1 Apensu
The Apensu deposit, a Kenyasi-style deposit, is located on the main Kenyasi Thrust Fault zone at the southern edge of the Ahafo trend.
The Apensu deposit had horizontal dimensions of approximately 4,200 x 600 m, and has been drill tested to 800 m vertical depth. The mineralization remains open at depth and towards the north along strike.
Mineralization was developed in mylonitic to cataclasite units along the sheared contact between footwall Birimian volcano–sedimentary units and hanging wall granodiorite. Footwall units included phyllonite, meta-volcano–sedimentary units, and mixed mylonitic volcano–sedimentary units.
| | | | | | | | |
Date: February, 2022 | | Page 6-2 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Figure 6-1: Project Geology
Note: Figure prepared by Newmont, 2021
| | | | | | | | |
Date: February, 2022 | | Page 6-3 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Figure 6-2: Stratigraphic Column
| | | | | | | | |
Date: February, 2022 | | Page 6-4 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Note: Figure prepared by Newmont, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 6-5 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
The shear zone varied in width from about 10–75 m in true width, with gold mineralization grading >0.5 g/t Au and varying from 30–150 m in width. Higher gold grades (>5 g/t Au) were hosted in, or immediately adjacent to, strongly-altered quartz–calcite veined cataclasite. The veins ranged from veinlets of 0.1–3.0 cm in width to silica-rich veins that ranged from 2–10 cm in width.
Six structural components were identified within the Apensu Main deposit. From oldest to youngest, these are:
•A zone of plastic deformation in the footwall mixed mylonite zones, graphitic and meta-volcano–sedimentary units;
•Three hanging wall splays off the Kenyasi Thrust, S1, S2 and S3, which form zones of mylonite that display brittle reactivation;
•A splay fault in the footwall that is interpreted as a plastically-deformed, locally anastomosing shear zone and is marked with graphite;
•A cataclasite unit that is formed by brittle deformation and re-activation of the rigid granitoid forms finely-crushed rock with local tectonic breccias.
Four types of alteration were recognized and assigned logging codes, from least to most altered:
•Code 0: greenschist minerals including chlorite, calcite and rare pyrite but no evidence of hydrothermal alteration;
•Code 1: slightly bleached due to the alteration of some chlorite to paler micas; contains ankerite and rare siderite plus calcite veinlets and patches of pyrite (less than 1%) and rare thin milky quartz veins (1 cm to 3 cm width) with occasional associated visible gold;
•Code 2: grayish to yellowish massive silica and sericite patches that are 1 cm to 10 cm in width and are controlled by small brittle shears or mylonitic zones;
•Code 3: pervasively silicified rock with strong sericite, rare iron carbonate veinlets, local albite as disseminated crystals, and the complete destruction of chlorite.
Mineralization is characterized by an association of silica–albite–carbonate–white mica–pyrite alteration, quartz veining and brittle chlorite-filled fractures. Better gold mineralization is developed in quartz–calcite veins associated with pyrite grains that can vary from fine disseminations to 1.5 mm in size. Gold occurs as single grains 1–20 µm in diameter but also commonly occurs in clusters of grains from 5–10 µm. There does not appear to be an association of gold with either arsenopyrite or rutile, and the gold is generally silver-poor, with <5 ppm Ag.
Visible gold occurs in the veined cataclasite. Locally, 0.2–2.0 cm wide quartz veins can return assays with more than 32 g/t Au from coarse gold. In the oxide zone, gold is associated with coarse goethite pseudomorphs after euhedral pyrite. Gold grains in the oxidized zone range from 5–10 µm. Manganese oxides are also observed in oxide mineralization.
A cross-section through the Apensu deposit is provided as Figure 6-3.
The Apensu Deeps represents a series of steeply-dipping, structurally-controlled, high-grade shoots beneath the Apensu open pit, and the two areas share similar structural relationships and controls. Apensu Deeps has dimensions of 2.7 km x 200 m and is tested to about 1 km
| | | | | | | | |
Date: February, 2022 | | Page 6-6 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
vertical depth. The Apensu Deeps area is subdivided into four zones, Apensu South, Apensu Gap, Apensu Main, and Apensu North (Figure 6-4). Mineralization remains open at depth in all zones, and to the north in Apensu North.
The deposits are hosted and aligned with the Kenyasi Fault and secondary splays and typically have moderate to steep dip towards the southeast. High-grade mineralization plunges vary from sub-vertical (Apensu South) to moderate southwesterly (Apensu Main and lower areas of Apensu North) to shallow southwesterly (upper areas of Apensu North).
Shear zone fabrics and fault geometries were inherited from early compressional deformation and include a strong cataclastic deformation of the hanging wall granitoids interpreted to be analogous to a crush breccia. Mineralized hanging wall splay faults are evident in the Apensu Main pit, and are well documented in drill core from Apensu Deeps. The intersection of these faults with the Kenyasi thrust appears to exert a primary control on the higher-grade ore-shoots as shown in Figure 6-4. The block model grades are used to highlight the structural controls and orientation of the higher-grade mineralization in that figure, with red representing grades >3 g/t Au.
The Apensu Gap area is different to the Apensu South and Apensu Main zones, as the area lacks the mafic unit that is associated with Apensu South, and the cataclasis is very weak. In this area, it appears that low-angle faults control and limit the extent of better grade gold mineralization.
Apensu North is developed in a structural jog repetition on the Kenyasi Fault beneath the Apensu Main deposit.
6.4.2 Awonsu
The Awonsu deposit, a Kenyasi-type deposit, developed on the sheared contact between mafic volcanic rocks, metasedimentary rocks and Dixcove granites. It is a continuation of the Amoma deposit, with the two mineralized zones separated by a zone of lower-grade, sub-economic mineralization.
The Awonsu deposit had horizontal dimensions of approximately 4,100 m x 150 m, and has been drill tested to 600 m vertical depth. The mineralization remains open at depth and towards the north along strike.
Footwall to the mineralization is a mixture of mafic volcanic and pelitic to turbiditic sedimentary units. The hanging wall is composed of granodiorite. Mixed mylonitic and cataclasite units and dilatant breccias, developed during plastic and ductile deformation occur in the sheared contact between the footwall and hanging wall.
Awonsu mineralization was typically more disseminated than that at Apensu. The shear zone varied in true width from 5–100 m, with gold mineralization >0.5 g/t Au ranging from 5–150 m in width.
Higher gold grades (>1.5 g/t Au) were hosted in, or immediately adjacent to, strongly-altered cataclasite, forming zones from 5–60 m in width. Grades >5 g/t Au were rare, but high-grade zones could be as much as 30 m wide. Gold grades of 0.5–1.5 g/t Au were more commonly developed in the fractured, moderately-altered hanging wall granodiorite.
| | | | | | | | |
Date: February, 2022 | | Page 6-7 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Figure 6-3: Drill Section, Apensu Main and Apensu Deeps
Note: Figure prepared by Newmont, 2021. Mixed zone = mineralized shear zone of the Kenyasi thrust. SA2-3 Alteration = sericite–albite alteration, with an intensity of 2 or 3; this alteration intensity is associated with mineralization. .
| | | | | | | | |
Date: February, 2022 | | Page 6-8 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Figure 6-4: Drill Section, Apensu Deeps
Note: Figure prepared by Newmont, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 6-9 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Lower-grade material typically formed a halo of 2–50 m in thickness. Locally, particularly on the northern side of the deposit, higher-grade areas within the hanging wall alteration zone occurred in discontinuous mylonite zones, and in fine stringer quartz veins. A narrower low-grade halo, ranging in width from 5–30 m, occurred in the footwall. As with Apensu, higher-grade shoots were associated with a southward plunge. Typically, the shoots averaged about 2–5 g/t Au versus >5 g/t Au in Apensu.
Five structural domains were logged. The oldest is the Kenyasi Thrust Fault. Two hanging wall duplex splays off the thrust, Kenyasi Splay 1 Fault and Kenyasi Splay 2 Fault are characterized by locally anastomosing zones of mylonite in granodiorite. The Kenyasi Footwall Splay Fault is distinguished as a plastically deformed, locally anastomosing shear zone marked by graphite. The youngest structure is the cataclasite unit, which may be a later brittle sinistral re-activation of the Kenyasi Thrust Fault.
Alteration was similar to that described for the Apensu deposit but was typically less intense. Two additional codes were used at Awonsu, Alteration Codes 4 and 5, which differentiated areas of stockwork veining (Code 4) and milky sheeted veins (Code 5).
Awonsu is the only deposit within the Ahafo Operations where multiple generations of cross-cutting milky to opaque quartz veinlets with open-space filling of minor pyrite and gold mineralization were observed. Distinct, sheeted, sub-parallel milky quartz veins, 0.1–2 cm in width, with minor pyrite and occasional coarse gold, cross-cut fresh to weakly-altered hanging wall granodiorite. The milky veins generally occurred in sets of 2–10 veinlets that were separated by 10 cm to 1 m.
The general geology of the Awonsu area was shown in Figure 6-1. A cross-section through the deposit is provided as Figure 6-5.
6.4.3 Subika
The Subika deposit, to date the only example of Subika-style mineralization, developed in the hanging wall of the Kenyasi Thrust Fault but lies on a separate and parallel fault zone to the thrust fault complex that hosts the Kenyasi-style deposits.
The portion of the Subika deposit being exploited in the open pit has horizontal dimensions of approximately 2.2 km x 400 m, and is tested to about 800 m in vertical depth. The portion of the deposit being exploited from underground is the continuity of mineralization below the open pit. This portion of the deposit has horizontal dimensions of approximately 3.7 km x 400 m, and is tested to about 1,600 m in vertical depth. Subika mineralization remains open at depth and along strike.
Alteration is controlled by the 5–40 m wide “Magic Fracture Zone” (MFZ), a continuous zone of quartz–albite–sericite–carbonate–pyrite alteration.
Better grades of gold mineralization occur in dilatant zones (MFZ), ranging in width from 1–60 m. Hanging wall lower-grade mineralization tends to extend only about 30 m from the dilatant zones. Higher grade shoots within the dilatant zones plunge south at 20º to 70º. The high-grade zones appear to be controlled by dilatant left jogs in the MFZ created by offsets across the mylonite zones.
| | | | | | | | |
Date: February, 2022 | | Page 6-10 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Figure 6-5: Cross-Section, Awonsu
Note: Figure prepared by Newmont, 2021. Mixed zone = mineralized shear zone of the Kenyasi thrust. SA2-3 Alteration = sericite–albite alteration, with an intensity of 2 or 3, this alteration intensity is associated with mineralization. Chonolith = intrusive igneous rock mass of wholly irregular form.
Four granitoid subset lithologies are recognized: diorite, gabbro, microdiorite, and diorite–gabbro mixed. Aplite and pegmatite dikes cross-cut the granitoid material.
Four structural zones are defined:
•The Victor Fault, on the southern end of the Subika deposit, is a major shear zone, 2–6 m wide, striking N60ºE, and dipping approximately 20–30º to the southeast. It locally anastomoses into three branches (Victor, Victor A, and Victor Lower Faults). It is cross-cut by dilatant breccias and brittle shears throughout, and displaces the Subika mineralization by as much as 40 m in an apparent left-lateral sense;
•The Kaalbas Fault lies just oblique to the overlying Victor fault, with a slightly more easterly trend and shallower dip;
•The Hatch Zone appears to be an anastomosing, almost east–west-trending structure, with two to three individual planes, each with 1 m to 3 m thickness developed within an overall 6–25 m wide structural zone. Mineralization appears to be displaced by about 50 m in the zone;
•The Deep One shear is apparently confined to the northern end of the deposit.
| | | | | | | | |
Date: February, 2022 | | Page 6-11 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Alteration associated with the Subika deposit is chemically similar to that in the Kenyasi-style deposits.
Mineralization is hosted in the MFZ, which typically contains >2–5 g/t Au over widths of 5–50 m. Quartz and carbonate veinlets are common with thickness between 1–50 mm. They form stockworks in some instances and most of the veins are impregnated with pyrite, and in some cases display sparse visible gold at the contact with the host rock.
The general geology of the Subika area was shown in Figure 6-1. A cross-section through the open pit portion of the deposit is provided as Figure 6-6.
| | | | | | | | |
Date: February, 2022 | | Page 6-12 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Figure 6-6: Cross-Section, Subika
Note: Figure prepared by Newmont, 2021. SA1 Alteration = sericite–albite alteration, with an intensity of 1, represents low-grade halo; SA2-3 Alteration = sericite–albite alteration, with an intensity of 2 or three, associated with mineralization.
| | | | | | | | |
Date: February, 2022 | | Page 6-13 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
7.0 EXPLORATION
7.1 Exploration
7.1.1 Grids and Surveys
The “Unified Ahafo Mine Grid” is used for the entire Project. This grid is based on the existing Ghana National Grid plus the addition of 1,000 m to the elevation in order to avoid negative elevations for mining purposes. All existing drill hole collar coordinates were recomputed to the Unified Ahafo Mine Grid.
The airborne survey used to construct the digital terrain model (DTM) for the Ahafo Operations was flown in 2004 before mining commenced. The topographic plans and DTM constructed from the survey have an accuracy of ± 1.1 m in x, y, and z directions.
7.1.2 Geological Mapping
Regional mapping was conducted at 1:50,000 scale to delineate areas of outcrop, alteration, faulting, and silicification that could act as additional vectors to mineralization and to support drill targeting.
All open pit and underground exposures are mapped as they become available, with emphasis on lithology, structural relationships and alteration, to help support folio development and understanding of key mineralization controls. These data are further applied to resource model development as well as exploration targeting.
Open pit mapping is performed at a scale of 1:3,000. An example of the mapping is provided in Figure 7-1
Underground mapping is done digitally by taking high-resolution overlapping photographs of the underground development walls and faces (taking into account the drive dimensions). These digital photographs are later stitched together to form panoramic images from which the structures, lithologies and alteration contacts are mapped in 3D Maptek Vulcan.
7.1.3 Geochemistry
Stream sediment sampling was used during the 1990s to vector into mineralized areas. There are no data on the numbers of samples taken, and many of these samples were taken outside the Ahafo Operations tenure area. Sample locations that are known are shown in Figure 7-2.
Soil sampling was primarily conducted in the 1990s and early 2000s. Over 50,000 samples were collected. Many of these samples were taken outside the current Ahafo Operations tenure area. Sample locations that are known are shown in Figure 7-3. Since 2017, deep-sensing geochemical samples have been collected (Figure 7-4). This is a proprietary Newmont technology that is applied in areas where there is no outcrop exposure due to extensive cover.
| | | | | | | | |
Date: February, 2022 | | Page 7-1 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Figure 7-1: Pit Mapping
Note: Figure prepared by Newmont, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 7-2 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Figure 7-2: Stream Sediment Sample Location Map
Note: Figure prepared by Newmont, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 7-3 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Figure 7-3: Soil Sample Location Map
Note: Figure prepared by Newmont, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 7-4 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Figure 7-4: Deep-Sensing Geochemical Sample Location Plan
Note: Figure prepared by Newmont, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 7-5 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Following the surveys, a “score” is applied to the area investigated, based on geological aspects of interest (e.g., lithology, alteration, mineralization). Collected data were processed to generate products for data integration and targeting.
Pits and trenches are excavated in areas highlighted as having anomalous assay results from soil sampling. The intent when pitting is to make contact with bedrock, or at least saprolite, for sampling and logging purposes. The initial cut is often to chest height for safety reasons. If additional depth is needed, then a safety layback is cut on at least one side of the trench. Samples are normally taken from the side or bottom of the trench on spacings of every 2 m or less as designated by the supervising geologist. A geological map of lithology, veins, structures, and alteration is made for each excavation before the excavation is backfilled.
7.1.4 Geophysics
7.1.4.1 Airborne Geophysics
Airborne geophysical surveys were conducted in 1994, 2005, 2007, 2016 and 2020 (Table 7-1; Figure 7-5). The surveys extend across the Ahafo district, and include areas outside of the Ahafo Operations area.
The high-resolution airborne surveys were useful in mapping the structures controlling mineralization in the Ahafo district on a detailed and refined scale. The data were used to enhance the existing geological interpretations over the area. Magnetic inversions performed using the datasets were useful in the generation of quality targets within the Ahafo district.
7.1.4.2 Ground Geophysics
Ground geophysical surveys were conducted from 1999–2020 (Table 7-1; Figure 7-6). The surveys extend across the Ahafo district, and include areas outside of the current Ahafo Operations area, either part of Ahafo North, or areas that Newmont no longer holds under mineral tenure.
Gradient array and pole–dipole IP/resistivity were identified as the most promising techniques. The resistivity data appeared to map silica alteration which tends to be closely associated with mineralization. Results of the semi-regional ground gravity survey indicate that the method may be a valid exploration tool for the Ahafo area. The main Ahafo deposits were located within gravity gradients.
7.1.5 Petrology, Mineralogy, and Research Studies
A number of structural, petrology, mineralogy, lithogeochemical, and research studies have been completed in the Ahafo Operations area since 1991. An MSc. thesis was completed on the structural evolution of the Subika deposit in 2011 by Emmanuel Baah-Danso. A PhD thesis completed in 2017 by Helen MacFarlane on the Sefwi Belt included some information from Newmont’s Ahafo exploration databases.
| | | | | | | | |
Date: February, 2022 | | Page 7-6 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Table 7-1: Geophysical Surveys
| | | | | | | | | | | |
Survey Type | Date | Operator | Note |
Airborne | 2004 | Gencor | Focused on western contact of the Sefwi belt with the Sunyani basin, where the contact fell within the Project area. 200 m line spacing; total area of about 1,450 km2. |
2005 | Fugro Airborne Surveys | 100 m line spacing, for 1,124 line-km; covered 96.9 km2 of Ahafo central. |
2007 | Fugro Airborne Surveys | Airborne magnetic survey (Midas). Altitude of 40 m at 100 m line separations. Total 3,940 line-km; survey area covered 349.6 km2. |
2016 | GeoTech Surveys | Airborne magnetic survey. 56 m altitude at 100 m line separations. Total 4,182 line-km; survey area covered 380 km2. |
2020 | Bell Geospace | Airborne gravity gradiometry survey. 60 m altitude at 200 m line separations. Total 7,806 line-km; survey area covered 466 km2. |
Ground | 1999 | SJ Geophysics | Induced polarization (IP)/resistivity surveys on the Ntotroso License. Dipole-dipole spacings were 50 m, and the very low frequency (VLF) survey was at 25 m spacings. The company also completed a ground magnetics survey (10 m spacings) over the Subika and Area F prospects. |
2003 | Newmont | IP/resistivity (gradient array on 25 x 50 m stations; pole-dipole and dipole-dipole on 50 m centers), total domain electromagnetics (TDEM), ground magnetics (5 x 50 m stations) and ground gravity (50 x 50 m stations) on the Yamfo South and Subenso deposits in Ahafo North. |
2004–2008 | Ahafo North and Ahafo South. Typically pole–dipole IP data were collected on 50 m centers, whereas the gravity array was on 25 x 50 m spacings. Ground magnetics data (5 x 50 m stations) also routinely collected |
2006 | Orientation gravity survey |
2006–2008 | Semi-regional ground gravity survey trialed at Ahafo |
2009–2014 | Offset pole–dipole IP survey data were collected at Subika. Two lines of transient electromagnetic (TEM) data completed at Amoma. Ground magnetic surveys conducted at Mampehia prospect |
2016-2020 | IP/resistivity (gradient array on 25 x 50 m stations; pole-dipole 50 m separation) conducted on Subika, Tanoso, Mankraho, Nanapfo, Mampehia and Mehame. |
| | | | | | | | |
Date: February, 2022 | | Page 7-7 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Figure 7-5: Airborne Geophysical Survey Location Plan
Note: Figure prepared by Newmont, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 7-8 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Figure 7-6: Ground Geophysical Survey Location Plan
Note: Figure prepared by Newmont, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 7-9 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
7.1.6 Qualified Person’s Interpretation of the Exploration Information
The Ahafo Operations are a mature site, and the initial exploration information collected using geochemical and geophysical methods is superseded by drill and mining data. The exploration information was used to successfully vector into areas of gold anomalism that were able to support mineral resource estimation and subsequent open pit and underground mining operations.
7.1.7 Exploration Potential
Within the immediate mining area, exploration potential includes the following:
•Subika: testing for extensions of the mineralization to the northeast, and down plunge of the currently-defined limits of the deposit;
•Apensu: drill testing of the northern strike and plunge extensions to the Apensu North mineralized shoot and Gap area depth potential.
•Subika-Apensu: potential mineralization along the deep linking structures between Subika Underground and Apensu Deeps;
•Awonsu: potential mineralization extents below the existing pit.
Near-mine exploration is planned to include:
•Evaluating structurally-favorable zones and potential repetitions along and down-plunge of the Kenyasi Thrust between the Apensu South and Awonsu deposits;
•Testing down plunge depth extensions to Subika;
•Amoma: potential for mineralization extensions below the existing pit.
•Drill testing of Subika structures and adjacent parallel fault trends defined by aeromagnetic, gradient array resistivity, 3D gravity models, geochemical datasets, and projections of the important, secondary, shallow-angle, low permeability faults which focus mineralization;
•Drill testing previously-identified geochemical and geophysical anomalies where these are potentially within trucking distance of the Ahafo process plant.
7.2 Drilling
7.2.1 Overview
7.2.1.1 Drilling on Property
A total of 12,902 drill holes (approximately 1.8 Mm) was completed within the Ahafo Operations area to December 31, 2021, including 4,792 core holes (1,321,915 m), 3,597 RC holes drill holes (234,566 m), 1,475 RC pre-collar/core tail holes (207,837 m), and 1,154 aircore drill holes (34,393 m). Drilling is summarized in Table 7-2. Drilling for areas that have current mineral resource estimates are summarized in Table 7-3.
| | | | | | | | |
Date: February, 2022 | | Page 7-10 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Table 7-2: Drill Summary Table
| | | | | | | | |
Drill Type | Number of Drill Holes | Meters Drilled (m) |
Aircore | 1,154 | 34,393 |
RC | 3,594 | 234,366 |
Core | 4,792 | 1,321,915 |
RC/core tail | 1,475 | 207,837 |
RAB | 1,887 | 30,922 |
| 12,902 | 1,829,433 |
Note: Table excludes grade control drilling. Metreage has been rounded; totals may not sum due to rounding.
Table 7-3: Drilling Supporting Mineral Resource Estimation
| | | | | | | | | | | |
Deposit | Drill Type | Number of Drill Holes | Meters Drilled (m) |
Apensu, Apensu South | Core | 1,004 | 366,017 |
RC/core tail | 189 | 40,411 |
RC | 429 | 22,473 |
Subtotal | 1,622 | 428,900 |
Awonsu | Core | 538 | 111,779 |
RC/core tail | 204 | 38,313 |
RC | 341 | 26,435 |
Subtotal | 1,083 | 176,526 |
Subika, Subika Underground | Core | 2,921 | 799,199 |
RC/core tail | 213 | 112,426 |
RC | 232 | 29,722 |
Subtotal | 3,366 | 941,347 |
| Totals | 6,071 | 1,546,773 |
Note: Subika total includes grade control drill holes. Metreage has been rounded; totals may not sum due to rounding.
A Project-wide drill collar location plan is provided in Figure 7-7 for the core and RC drilling, and Figure 7-8 shows the aircore drilling completed.
Between 1992 and 2002, drilling was completed primarily for early-stage, exploration-focused programs and for initial resource estimates. From 2002, drilling was used to support advanced-stage project evaluation, deposit, pit and underground delineation.
| | | | | | | | |
Date: February, 2022 | | Page 7-11 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Figure 7-7: Drill Collar Location Plan (Core and RC)
Note: Figure prepared by Newmont, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 7-12 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Figure 7-8: Drill Collar Location Map (Aircore)
Note: Figure prepared by Newmont, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 7-13 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
7.2.1.2 Drilling Excluded For Estimation Purposes
RAB and aircore drilling are not used to support estimation of either mineral resources or mineral reserves.
In addition, drill holes with failed quality control checks for data such as down hole survey, collar, and assays are excluded from the final data extraction used for resource/reserve estimation.
7.2.2 Drill Methods
Aircore drilling was primarily used as a first-pass evaluation tool of soil sample anomalies to bedrock. Drilling was completed by multiple contractors during Normandy’s tenure, all of which used aircore-only drill rigs. The primary drill contractor for the aircore programs completed by Newmont was African Mining Services (AMS), who used an ED100-type drill rig.
RC drilling was used as a resource delineation tool from 1995 to 2012. Drill contractors included Boart Longyear (BLY), AMS, and Geodrill. The drilling firms used both dedicated RC and multipurpose-type drill rigs, including ED703, ED704, ED045, ED062, KL900, KL200, and LF4252 rig types.
Core drilling is used to support resource estimates, and to infill in areas of predominantly RC drilling. Core drilling was completed in phases, from 1995 to the Report date. Drill holes classified as core-drilled include both RC pre-collared holes and those wholly drilled as cores.
7.2.3 Logging
Aircore drill hole logging included lithologies, alteration, oxidation states, and presence of aquifers.
Geological logging of RC drill data included lithology, alteration state, oxidation, and presence of water. Logging used pre-set codes. Drill chips were logged at the drill site, and a chip tray record of each 1 m interval retained for reference.
Detailed geological logging is carried out on all core holes, and focuses on descriptions and graphical logging of geological relationships, characteristics and mineralization. Lithology, alteration, veining, sulfide content, oxidation type and structural information are consistently captured digitally using a tablet personal computer via Visual Logger application and loaded to a global exploration database (GED) for storage. The Visual Logger application contains the standard geologic codes for the logging.
The senior project geologist for a particular project performs a minimum of 20% quality checks on all geological logging and documents the findings.
Historically, geotechnical logging of core was performed on selected drill holes from infill drilling programs to capture core recovery and rock quality designation (RQD). The selected interval for geotechnical logging was largely dependent on the observed geotechnical features. This practice was replaced by performing the geotechnical logging run by run or block to block for the entire length the hole and for all the drilled holes. Geologists log core recovery, RQD, joint condition rating, fracture frequency and strength. Information captured using Visual Logger and loaded into the GED. More specialized geotechnical logging is done by geotechnical engineers for the holes drilled specifically for geotechnical purposes.
| | | | | | | | |
Date: February, 2022 | | Page 7-14 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
7.2.4 Recovery
Recovery was not usually recorded for the aircore drill programs but is typically very high.
Except for the first few meters of individual RC holes, where recovery is typically in the 20–40% range, recovery is generally about 95–98%.
Core recovery is normally 100%, except for very rare times when faults and/or graphitic shear zones are encountered. The mineralized zone, which is silicified and brecciated, is a solid rock and recovery is almost always 100% in mineralization.
7.2.5 Collar Surveys
Aircore drill hole collars were located by the survey department and verified by geology personnel.
Collars of drill holes completed prior to 2005 were surveyed by surveyors, using optical instruments and in the local mine grid coordinate system. In September 2006, Newmont transformed all the spatial data at the Ahafo Operations to a common and unified survey grid based on the projection of the Ghana National Grid. A vertical offset was added to elevations referenced to mean sea level to avoid negative values. The unified grid was called the Ahafo Unified Ghanaian National Grid. Collars of drill holes completed afterwards were surveyed by Newmont surveyors, using global positioning system (GPS) equipment and in the Ahafo Unified Ghanaian National Grid coordinate system. Data are electronically sent to the database manager.
7.2.6 Down Hole Surveys
Aircore drill holes were not down-hole surveyed. A Welnav downhole survey camera was used for RC drill holes. Core hole downhole surveys were performed with a variety of instruments, including multi-shot Sperry-Sun, Welnav, Reflex EZ-Shot and Reflex Multishot tools. All surveys were performed by the drilling company, then checked and approved by geological staff.
Magnetic declinations are adjusted for drift. The declination factor is subtracted from the magnetic reading provided by the drilling services contractor.
Quality control is completed for 5% of the holes drilled.
7.2.7 Grade Control
Newmont currently employs 10 Drilltech D45 blast hole rigs, which drill 9.5 m vertical blast holes (i.e., 8 m bench plus 1.2 m sub-drill) for grade control sampling in fresh rock. The sub-drill is not sampled for grade control purposes. Blasthole spacing is at approximately 4 m x 4.5 m spacing in both ore and waste zones.
7.2.8 Comment on Material Results and Interpretation
Drill holes are oriented with an inclination ranging from -45º to -88º for surface holes and -74º to -32º for underground holes to accommodate the steeply-dipping nature (typically -55º to -75º) of the Ahafo Operations deposits, resulting in an intersection generally representing 75–85% of
| | | | | | | | |
Date: February, 2022 | | Page 7-15 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
true width. Drilling is generally orientated perpendicular (300–330º) to the strike of the orebodies (040º –050º) for surface drill holes. Underground drill holes are typically collared from the footwall into the hanging wall of the orebody, the opposite direction to the surface drill holes.
Local variation in drill orientations may be present to accommodate infrastructure constraints.
7.3 Hydrogeology
Water quality monitoring done on site is based on a monitoring plan developed to guide ongoing sampling and analysis of process fluid including groundwater and surface water collected in conjunction with Newmont’s water resources monitoring program to meet operational needs and environmental protection requirements. Sampling conducted under this plan is performed by Newmont personnel and/or contractors under the direction of Newmont staff. Monitoring data are used to quantify water quality such that any mine-related impacts to the environment can be determined and, if necessary, mitigated.
7.3.1 Sampling Methods and Laboratory Determinations
Surface and ground water monitoring routinely conducted, with sample intervals, depending on what is being monitored, that can be daily, weekly, monthly, quarterly, or annual. Samples of surface water are analyzed in the field using hand-held instruments for the following parameters: pH, specific conductivity, dissolved oxygen, water temperature, and turbidity. The color of the water is also recorded on the field form.
Community water supply wells are sampled using existing well pumps. Field parameters including pH, SC, temperature, dissolved oxygen, and turbidity are collected.
Standpipes and vibrating wire piezometers (VWPs) are installed in the perimeter of the pits to monitor groundwater levels and pore pressures for the purpose of slope stability.
Stream flow at designated stations is measured using a current meter (electromagnetic, and/or equivalent-type).
Water sample analyses are conducted by SGS or the mine site laboratory. SGS is an accredited environmental laboratory in Ghana and appropriate certifications for chemical analysis of hydrological samples. The Newmont mine laboratory is used for selected analyses, such as physical parameters, microbiology and particular nutrients.
Full suite parameters, such as nutrients and other chemicals, total and dissolved metals are assayed at one of SGS, ALS, or Intertek in Ghana. These laboratories may be used to analyze split samples as part of the QC process. All laboratories use designated analytical methods or a comparable method, and meet specific QC requirements. The laboratories hold ISO17025 accreditations for selected chemical analytical techniques.
Laboratory analytical methods used are based on the most recent edition of the American Public Health Association’s (APHA) “Standard Methods for the Examination of Water and Wastewater”, and standards from the International Standards Organization.
Quality assurance and quality control (QA/QC) measures can include:
•Ensuring sites selected are representative;
•Reviewing field forms for adherence to proper calibration and sample collection procedures | | | | | | | | |
Date: February, 2022 | | Page 7-16 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
•Achieving completeness goals of 90%, where completeness is calculated as the number of valid measurements divided by the total number of planned measurements, expressed as a percentage;
•Inserting field duplicates, laboratory duplicates, matrix spike duplicates, or laboratory control sample duplicates;
•Inserting field blanks, matrix spikes, laboratory control samples, and surrogate spikes
•Using USEPA-accepted analytical methods, where available and as appropriate;
•Checking the comparability of data collected.
7.3.2 Groundwater Models
A groundwater model was developed in 2016 by Golder Associates for the Ahafo Operations, primarily to support the open pit mines and the planned Subika underground mine. Evaluations of the potential to also underground mine adjacent to the Apensu open pit required updates to the groundwater model.
The existing FEFLOW-hosted Ahafo regional groundwater flow model was recalibrated to better represent the inflows and groundwater levels monitored in proximity of the various mines. The 2015–2016 model assumptions resulted in higher predicted groundwater inflows to the underground mine than that recorded over the 2017–2019 period, and consequently the associated drawdown cones predicted were larger than those measured based on available borehole water levels. As a result, the hydraulic conductivities assigned to the saprock, fractured and fresh bedrock zones were reduced. Lower hydraulic conductivity values and lower groundwater ingress rates were modeled to match the data collected, and the cone of depression extent was reduced.
7.3.3 Water Balance
The Ahafo Operations site-wide GoldSim model has been in use for over a decade as an operational support and long-term planning tool for mine water management at the operations. Calibration of the model is performed at least once annually through the collation and entry into the model of empirical monitoring/operational reporting data spanning a minimum of 12 months prior to the date of each calibration exercise.
Data inputs used in the calibration process included mined tonnages, mill throughput, pit dewatering rates, tailings densities, TSF reclaim rates and other factors that are likely to influence the physical water balance. Deterministic model simulations were then performed, with results relating to flows and/or storage inventories compared against measured values at key calibration locations across the model domain.
Updates of the GoldSim site-wide water balance model for Ahafo was completed during Q3 of 2020 and included Ahafo’s 2021 mine plan and production schedule. Historical and projected inflows to the Subika Underground as defined by 2020 numerical groundwater modelling were incorporated into the GoldSim model.
In parallel with the model update and calibration process completed in Q3 2020, the GoldSim model was used to support investigations performed under the Ahafo Site Water Management Study, primarily on the LOM dewatering strategy around the Apensu pit, and the decision on the
| | | | | | | | |
Date: February, 2022 | | Page 7-17 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
need for and timing of additional treatment capacity, and the requirement of an impacted water pond.
7.3.4 Comment on Results
To the Report date, the hydrogeological data collection programs have provided data suitable for use in the mining operations, and have supported the assumptions used in the active pits and underground operations.
7.4 Geotechnical
The following general information are collected for geotechnical assessment of both open pit and underground excavations:
•Rockmass classification and characterization data to estimate the rock quality;
•Structural data to determine potential structural-controlled failures;
•Damage mapping data to determine stress-related failures.
7.4.1 Sampling Methods and Laboratory Determinations
Rock mass (laboratory testing) and hydrogeology data are used for structural characterizations to support pit walls. Examples of tests done to determine the mechanical properties of rocks are tensile strength, uniaxial compressive strength, and triaxial compressive tests.
Core samples are sent to a laboratory for various geotechnical purposes such as determining the mechanical properties of the rock and estimating stress field of the rock. Core samples are selected for laboratory purposes, and are based information such as the core integrity, core quality, and geological variability. The samples are carefully selected at different depths with sample lengths based on the International Society for Rock Mechanics’ recommendation of 2.5–3 times sample diameter for elastic property testing. Current testing facilities include Rocklab in Pretoria, South Africa; E-Precision, Bibra Lake, Western Australia; and the West Australian School of Mines in Kalgoorlie, Western Australia. The laboratories are independent of Newmont. There are no internationally recognized accreditations for geotechnical techniques.
Sample selection for acoustic emission (AE) technique and deformation rate analysis (DRA) stress measurement tests is based on varying sample depths specified. Generally, samples are be selected from about 150 m below surface and sample depth ranges are approximately 200 m apart. Core samples selected for AE/DRA testwork have minimal fracture breaks and the orientation marks/line are be checked for consistency. Core samples for laboratory testing are wrapped with clean cloth and placed in either wooden or metal boxes that are lined with visco-elastic foam to minimized disturbances during shipment.
Scanline and window mapping techniques are used to characterize the various discontinuity sets within the rock mass, which aids in defining potential failure modes likely to occur in the stope and pit walls. Several aspects such as rock mass condition, stope geometry, structural fabric, stress conditions, etc. are considered during stope designs.
Run-of-mine (ROM) waste rock is used as fill material in the underground excavations. The suitability of the fill material is determined via the mechanical properties of the rock and
| | | | | | | | |
Date: February, 2022 | | Page 7-18 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
fragmentation analysis to define material granularity and appropriateness. The fragmentation analysis is conducted by a qualified backfill engineer.
Blasts are measured with a geophone system to quantify the effect of vibrations into the rock mass. There are prism arrays on the pit walls to measure slope displacements. Radars are also employed to monitor slope movements in real time. A micro-seismic monitoring system is used for monitoring seismic activities in the rock mass. Extensometers are used for displacement monitoring of some selected underground excavations.
A fall-of-ground register is maintained for all rock events, which provides brief summary of sequence and nature of the rock event.
7.4.2 Comment on Results
The geological hard rock setting at the Ahafo Operations is well understood and displays reasonable consistency in the various open pits located on site. Additional testing continues to confirm the consistency of material strengths and parameters.
To the Report date, the geotechnical data collection programs have provided data suitable for use in the mining operations, and have supported the assumptions used in the active pits and underground operations. The geotechnical testwork and monitoring is used in the pit and underground designs that are discussed in Chapter 13.
| | | | | | | | |
Date: February, 2022 | | Page 7-19 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
8.0 SAMPLE PREPARATION, ANALYSES, AND SECURITY
8.1 Sampling Methods
BLEG samples were collected from suitable drainages, as 2–5 kg samples, and placed in pre-numbered calico bags. The sample location was recorded, typically on aerial photographs.
Soil samples were collected as 2 kg samples from 15–20 cm depths in the soil profile, a description recorded, then samples were placed in a pre-numbered calico bag.
Rock chip samples were typically collected as 2–5 kg of grab samples from surface outcrops. Sample locations were recorded, together with a geological description.
Trench and pit samples were normally collected from the side or bottom of the trench on about 2 m spacings, or as designated by the supervising geologist. Samples ranged from 2–5 kg, and each sample position was recorded with a geological description.
Aircore drill samples were typically taken on 2 m intervals down hole.
RC samples were generally taken on 1 m intervals down hole, split using a Gilson riffle splitter, with quarter samples collected in pre-numbered RC sample bags.
Core was cut along marked orientation lines, using a diamond saw. Sample lengths varied from 0.2–1.5 m, with sample intervals selected based on the geological features of the core, including alteration.
8.2 Sample Security Methods
Sample collection, preparation, and transportation have always been performed by Newmont personnel using Newmont vehicles, or by the relevant commercial laboratory vehicle. Chain-of-custody procedures consist of sample submittal forms sent to the laboratory with sample shipments to make certain that all samples are received by the laboratory.
8.3 Density Determinations
Newmont’s protocols for specific gravity (SG) determination require that a minimum of 30 SG samples per material type (domain) are collected at the initiation stage and identification stage of any project. For more advanced projects, SG samples are typically collected at approximately 10–20 m intervals.
SG determinations were completed by the Normandy-operated Ahafo Mobile Sample Preparation Unit (MSPU) and the SGS laboratory in Tarkwa (SGS Tarkwa). Currently, determinations are performed onsite by Newmont technicians. In all cases, SG values were measured by water displacement methods. Values range from 1.76 in saprolitic material to 2.79 in fresh rock.
Quality control (QC) measurements are performed on a minimum of 5% of samples by an independent external laboratory; currently either SGS Ahafo or ALS Kumasi. Quality assurance and quality control (QA/QC) measurements are validated by Newmont senior geological staff.
| | | | | | | | |
Date: February, 2022 | | Page 8-1 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
8.4 Analytical and Test Laboratories
A number of independent laboratories have been used since 1993.
During the Normandy operating period, the primary laboratories were Transworld Laboratories, in Tarkwa, Ghana, and SGS Kumasi and SGS Tarkwa.
Newmont used UltraTrace Laboratory Pty Ltd (UltraTrace) for BLEG geochemical sampling.
Umpire laboratories used include ALS Vancouver in Canada, Gencor Laboratories, in Johannesburg, South Africa (Gencor); Inchcape Laboratory in Obuasi, Ghana (Inchcape); Genalysis Laboratories in Perth, Australia (Genalysis); Anglo-American Research Laboratories in Johannesburg (AARL); Omac Laboratories in Ireland (Omac); and Performance Laboratories in Johannesburg (Performance).
SGS Tarkwa was the primary laboratory for all drill programs for the period June 2003 to 2010. In addition to SGS, ALS Chemex (ALS) has provided laboratory services to Newmont Ghana from 2010 to date, and has used branch laboratories in various locations, including ALS Kumasi, ALS Vancouver and ALS Johannesburg.
Both SGS and ALS are independent laboratory groups that operate globally, and the SGS/ALS laboratories used for the Project are accredited to ISO/IEC17025 for selected sample preparation and analytical techniques. Currently SGS Ahafo is the primary laboratory used for the Ahafo deposits.
The on-site mine laboratory, SGS Ahafo, is managed by SGS and is used to prepare and analyze grade control, and metallurgical samples. It can also be used as the sample preparation facility for exploration/development drill holes; there is a separate sample preparation site that has dedicated equipment and is only used to process exploration samples. The on-site mine laboratory holds ISO/IEC17025 accreditation for selected sample preparation and analytical techniques.
8.5 Sample Preparation
Sample preparation methods for the various major sampling types is summarized in Table 8-1.
8.6 Analysis
The following analytical methods have been used:
•Au by fire assay and atomic absorption spectroscopy (AAS);
•Multi-element Ag, As, Bi, Ca, Cd, Cu, Fe, Hg, In, Mn, Mo, Ni, Pb, Sb, Te, Tl, U, W, Y, and Zn; aqua regia digest followed by ICP-MS finish;
•S and C analysis via LECO.
| | | | | | | | |
Date: February, 2022 | | Page 8-2 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Table 8-1: Sample Preparation Procedures
| | | | | | | | |
Laboratory | Sample Type | Preparation Procedure |
Newmont, UltraTrace | Stream sediment | None required |
ALS Kumasi | Soil | Dried, crushed to nominal 90% passing -2 mm, pulverized to 90% passing -75 µm |
SGS Ahafo, ALS Kumasi | Rock chip; pit/trench; aircore; RC | Dried, crushed to nominal 90% passing -3 mm, pulverized to nominal 90% passing -75 µm |
SGS Ahafo, ALS Kumasi | Core | Dried, crushed to nominal 90% passing -2 mm, pulverized to 90% passing -75 µm |
8.7 Quality Assurance and Quality Control
Newmont has considerably modified the QA/QC program at Ahafo from that used prior to 2004. Newmont maintains a QA/QC program for the Ahafo Operations. This includes regular submissions of blank, duplicate and standard reference materials (standards) in samples sent for analysis.
Results are regularly monitored. Standard results indicate that assays from each of the laboratories, Newmont’s internal mine laboratory, SGS Ahafo, ALS Kumasi, are sufficiently accurate to support mineral resource and mineral reserve estimation and mine planning. In early programs, the number of outliers was on the high side; however, after investigation, the majority of the issues were found to be caused by mislabeling and sample swapping. Sample labelling and handling procedures were improved during 2012, reducing the number of failed standards in later campaigns.
Blank results indicate that contamination is not a significant concern.
Data for field, preparation and pulp duplicate types indicates that the data are acceptably precise at the primary laboratories. The number of failures due to mixed and mislabeled samples was a concern in early programs; however, procedures for inserting and tracking duplicate samples were significantly upgraded.
Approximately 5% of pulp samples analyzed at the primary laboratory were routinely submitted to an umpire laboratory. Umpire laboratory results typically compare well with the original assay results, with the precision and bias within acceptable quality ranges.
8.8 Database
All drilling-related data are stored on a Microsoft SQL server engine which supports multi-user access. Assays, downhole surveys, and collar surveys are stored in the same file as the geologic logging information. In addition, sample preparation and laboratory assay protocols from the laboratories are kept on file. The database is administered by a dedicated database manager. Security and access to the database is achieved through Microsoft Windows server technology authentication and file permissions. These are administered by the onsite Information Technology department.
All historic paper records are filed in a manner that allows for quick location and retrieval of any information desired.
Digital data are regularly backed up. Copies of the digital database are securely stored offsite.
| | | | | | | | |
Date: February, 2022 | | Page 8-3 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
8.9 Qualified Person’s Opinion on Sample Preparation, Security, and Analytical Procedures
The sample preparation, analysis, quality control, and security procedures used by the Ahafo Operations have changed over time to meet evolving industry practices. Practices at the time the information was collected were industry-standard, and frequently were industry-leading practices.
The Qualified Person is of the opinion that the sample preparation, analysis, quality control, and security procedures are sufficient to provide reliable data to support estimation of mineral resources and mineral reserves:
•Drill collar data are typically verified prior to data entry into the database, by checking the drilled collar position against the planned collar position;
•The sampling methods are acceptable, meet industry-standard practice, and are adequate for mineral resource and mineral reserves estimation and mine planning purposes;
•The density determination procedure is consistent with industry-standard procedures. A check of the density values for lithologies across the different deposits indicates that there are no major variations in the density results;
•The quality of the analytical data is reliable, and that sample preparation, analysis, and security are generally performed in accordance with exploration best practices and industry standards;
•Newmont has used a QA/QC program comprising blank, standard and duplicate samples. Newmont’s QA/QC submission rate meets industry-accepted standards of insertion rates;
•Verification is performed on all digitally-collected data on upload to the main database, and includes checks on surveys, collar co-ordinates, lithology, and assay data. The checks are appropriate, and consistent with industry standards.
| | | | | | | | |
Date: February, 2022 | | Page 8-4 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
9.0 DATA VERIFICATION
9.1 Internal Data Verification
9.1.1 Data Validation
Newmont personnel regularly visit the laboratories that process Newmont samples to inspect sample preparation and analytical procedures. Observations not in conformity with Newmont procedures are recorded in Project files and communicated to the appropriate laboratory for corrective action to be taken.
The database is checked using electronic data scripts and triggers (see discussion in Chapter 8.8).
Newmont has conducted a number of internal data verification programs since 2002, which included the following reviews:
•Logging consistency, down hole survey, collar coordinate and assay QA/QC data;
•Geological procedures, resource models and drill plans;
•Sampling protocols, flow sheets and data storage;
•Check assay program results;
•SG data.
9.1.2 Reviews and Audits
Newmont conducts internal audits, termed Reserve and Resource Review or 3R audits, of all its operations. These audits focus on:
•Reserves processes: geology and data collection; resource modelling; geotechnical; mine engineering (long term) for open pit and underground operations; mineral processing (development); sustainability and external relations; financial model;
•Operations process: ore control; geotechnical and hydrogeology (operational); mine engineering (operational) for open pit and underground operations; mineral processing (operational); reconciliation.
The reviews assess these areas in terms of risks to the contained metal content of the mineral resource and mineral reserve estimates, or opportunities to add to the estimated contained metal content. Findings are by definition areas of incorrect or inappropriate application of methodology or areas of non-compliance to the relevant internal Newmont standard (e.g., such as documents setting out the standards that are expected for aspects of technical services, environmental, sustainability and governmental relations) or areas which are materially inconsistent with published Newmont guidelines (e.g., such as guidelines setting out the protocols and expectations for mineral resource and mineral reserve estimation and classification, mine engineering, geotechnical, mineral processing, and social and sustainability). The operation under review is expected to address findings based on the level of criticality assigned to each finding.
| | | | | | | | |
Date: February, 2022 | | Page 9-1 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Ahafo Operations 3R audits were conducted in 2012, 2014, 2016, 2018, and 2020. Earlier audits, known as Five Star reviews, were undertaken in 2005 and 2006.
The 2020 3R audit found that the Ahafo Operations were generally adhering to Newmont’s internal standards and guidelines with respect to the estimation of mineral resources and mineral reserves. The review team identified no material issues with the mineral resource and mineral reserve estimation processes. The team made a number of recommendations for site-based improvements; however, none of these recommendations were considered critical to implement. Recommendations included suggestions for improvement in the modelling process, review of site-wide cut-off grade strategies, and review of contact water management.
9.1.3 Mineral Resource and Mineral Reserve Estimates
Newmont established a system of “layered responsibility” for documenting the information supporting the mineral resource and mineral reserve estimates, describing the methods used, and ensuring the validity of the estimates. The concept of a system of “layered responsibility” is that individuals at each level within the organization assume responsibility, through a sign-off or certification process, for the work relating to preparation of mineral resource and mineral reserve estimates that they are most actively involved in. Mineral reserve and mineral resource estimates are prepared and certified by QPs at the mine site level, and are subsequently reviewed by QPs in the Newmont-designated “region”, and finally by corporate QPs based in Newmont’s Denver head office.
9.1.4 Reconciliation
Newmont staff perform a number of internal studies and reports in support of mineral resource and mineral reserve estimation for the various Ahafo Operations mines. These include reconciliation studies, mineability and dilution evaluations, investigations of grade discrepancies between model assumptions and probe data, drill hole density evaluations, long-range plan reviews, and mining studies to meet internal financing criteria for project advancement.
9.1.5 Subject Matter Expert Reviews
The QP requested that information, conclusions, and recommendations presented in the body of this Report be reviewed by Newmont experts or experts retained by Newmont in each discipline area as a further level of data verification.
Peer reviewers were requested to cross-check numerical data, flag any data omissions or errors identified, review the manner in which the data were summarized and reported in the technical report summary, and check the interpretations arising from the data as presented in the Report. Reviewers were also asked to check that the QP’s opinions stated as required in certain Report chapters were supported by the data and by Newmont’s future intentions and Project planning.
Feedback from the subject matter experts was incorporated into the Report as required.
9.2 External Data Verification
Data verification by external consultants in support of mine development and operations is summarized in Table 9-1. No material issues were identified in the reviews.
| | | | | | | | |
Date: February, 2022 | | Page 9-2 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Table 9-1: External Data Verification
| | | | | | | | |
Year | Company | Note |
2003 | AMEC Americas Ltd | Audited database |
2014 | Optiro Pty Ltd | Review of Subika resource model |
2016 | AMEC Americas Ltd | Review of resource models; geology and data collection; mineral resource estimates; mineral reserve estimates; mine planning; geotechnical data (mining, infrastructure); metallurgy and mineral processing; financial analysis |
9.3 Data Verification by Qualified Person
The QP performed site visits as discussed in Chapter 2.4. Observations made during the visits, in conjunction with discussions with site-based technical staff also support the geological interpretations, and analytical and database quality. The QP’s personal inspection supports the use of the data in mineral resource and mineral reserve estimation, and in mine planning.
The QP participated in the 3R audit in 2018, with responsibilities as the reviewing mining engineer and the audit team lead.
The QP receives and reviews monthly reconciliation reports from the mine site. These reports include the industry standard reconciliation factors for tonnage, grade and metal; F1 (reserve model compared to ore control model), F2 (mine delivered compared to mill received) and F3 (F1 x F2) along with other measures such as compliance of actual production to mine plan and polygon mining accuracy. The reconciliation factors are recorded monthly and reported in a quarterly control document. Through the review of these reconciliation factors the QP is able to ascertain the quality and accuracy of the data and its suitability for use in the assumptions underlying the mineral resource and mineral reserve estimates.
9.4 Qualified Person’s Opinion on Data Adequacy
Data that were verified on upload to the database, checked using the layered responsibility protocols, and reviewed by subject matter experts, are acceptable for use in mineral resource and mineral reserve estimation.
| | | | | | | | |
Date: February, 2022 | | Page 9-3 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
10.0 MINERAL PROCESSING AND METALLURGICAL TESTING
10.1 Introduction
Metallurgical testwork was conducted at Newmont Metallurgical Services and Hazen Research under the direction of Newmont personnel. An earlier phase of testwork in 2000 was completed under the direction of and interpreted by Lycopodium Pty Ltd.
Each year, samples are selected to represent the next three years of production in mine-to-mill testing, to ensure there sufficient current testwork to support knowledge of the mill feed materials, and support process assumptions.
10.2 Test Laboratories
Newmont Metallurgical Services is an in-house metallurgical testing and research and development laboratory. Hazen Research is an independent commercial metallurgical testing facility. There is no international standard of accreditation provided for metallurgical testing laboratories or metallurgical testing techniques.
10.3 Metallurgical Testwork
Work completed included mineralogy, chemical analysis; leaching; leach characterization (as well as determination of cyanide and lime consumptions); comminution characterization for various grind sizes; Bond rod and ball mill work indices, abrasion indices and JKTech drop weight comminution parameters; grindability work; heap leach testwork; gravity concentration tests; determination of thickening and slurry pumping characteristics; rheology; tailing characterization and tailings geochemical tests; and oxygen addition. These tests were used to design the plant, which commenced operations in 2006, and support ongoing plant operations.
Results from the test work program prior to 2006 were used to develop equations to forecast throughput, recovery and cost for each ore type. The throughput, recovery and cost models have subsequently been validated and updated using results of mine-to-mill test work conducted after plant startup, and the actual process plant throughput and recovery performance.
In 2019, mine-to-mill testing was performed to characterize the material that would be treated in 2022–2024.
The current mineral reserve and mineral resource metallurgical recovery assumptions have not changed significantly since plant start-up. Recoveries for two deposits, Subika open pit and Awonsu pit phases 3 and 4, were updated in the 2019 Ahafo mine-to-mill metallurgical study. The mine plan recovery functions include allowances for gold losses due to solution and carbon losses to allow for more accurate recovery projections. The current mine plan recovery functions include a 4.5% recovery upscale factor for all deposits other than Apensu Deeps, as operational results consistently exceed laboratory recovery estimates by 4.5%. The reason for the difference (scale-up) is due to the difference in particle size distributions generated in a laboratory mill versus an operational mill (a finer distribution is generated during operations, which leads to enhanced recoveries).
| | | | | | | | |
Date: February, 2022 | | Page 10-1 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
In the case of Apensu Deeps, which is under evaluation, testwork focused on using the current Ahafo metallurgical plant to treat the material. Drop weight and abrasion indices are generally higher than for the Apensu open pit material, and the Bond ball mill work index is similar. It was discovered that un-leached gold in the high-grade material is predominantly locked in pyrite, resulting in a lower recovery. Test results indicated that a finer grind of the high-grade material will improve recovery rates significantly. Additional tests are planned.
The Ahafo Mill Expansion (AME; also referred to as Line 2) was commissioned in September 2019. It entails a separate crushing/grinding circuit, and three additional leach tanks and tailings pumps. Line 2 is adding approximately 50% more capacity to the Ahafo processing plant. The Line 2 design throughput rate is 400t/hr, which is currently been achieved.
10.4 Recovery Estimates
The feed to the plant is currently both primary and oxide ore. Based on the life of mine plan, it is expected that the remaining 202 kt of stockpiled oxide ore will be processed in 2022. Average throughput projection is 9.5Mt per annum from 2022 to the end of mine life.
Recovery models were derived at a grind size of P80 106 µm, based on actual testwork conducted at current plant conditions, for the various deposits. These equations were used to determine the block by block recovery and the individual blocks recoveries were coded into the model for floating pit shells. Stockpiled material is tracked by pit source and is assigned the same metallurgical recovery as the deposit it is sourced from.
Forecast recoveries for the LOM are provided in Table 10-1.
10.5 Metallurgical Variability
Samples selected for metallurgical testing during feasibility and development studies were representative of the various styles of mineralization within the different deposits. Samples were selected from a range of locations within the deposit zones. Sufficient samples were taken and tests were performed using sufficient sample mass for the respective tests undertaken.
Samples are currently selected for every 300,000 t of ore to be processed, using a grade/tonnage table, and used in mine-to-mill testing.
10.6 Deleterious Elements
The Ahafo ores are clean ores containing low levels of problematic elements. The ores do not contain significant amounts of arsenic, selenium and mercury to indicate health or environmental risks. No appreciable levels of rich-solution-robbing materials are present in the ores. The ores contain low sulfide sulfur, and low concentrations of primary cyanide consumers (copper, nickel and zinc), which suggest that cyanide consumption may increase.
| | | | | | | | |
Date: February, 2022 | | Page 10-2 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Table 10-1: Ahafo Recovery Estimates
| | | | | |
Deposit/Zone | Metallurgical Recovery (%) |
Apensu Deeps | 84 |
Apensu underground | 83 |
Apensu South underground | 81 |
Awonsu phases 1 and 2 | 85 |
Awonsu phases 3 and 4 | 89 |
Subika open pit | 93 |
Subika underground | 94 |
Note: all recoveries presented on an average LOM projected grade basis.
10.7 Qualified Person’s Opinion on Data Adequacy
The QP notes:
•Metallurgical testwork completed on the Project is appropriate to establish optimal processing for the different deposits that comprise the Ahafo Operations;
•Testwork was completed on mineralization that is typical of the deposit styles. The testwork indicates that mineralization typically becomes harder with depth, and that in the primary ore gold is associated with fine pyrite mineralization or silicates;
•The mill throughput and associated recovery factors are considered appropriate to support mineral resource and mineral reserve estimation, and mine planning;
•Additional testwork is required for Apensu Deeps to confirm whether the 4% upscale factor used for all other Ahafo deposits is applicable to this mineralization;
| | | | | | | | |
Date: February, 2022 | | Page 10-3 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
11.0 MINERAL RESOURCE ESTIMATES
11.1 Introduction
The close-out date for the databases used in the various mineral resource estimates are as follows:
•Subika open pit: April 2020;
•Apensu-Awonsu : January, 2020;
•Subika underground: June, 2021;
•Apensu underground: July, 2021.
Geological models were constructed using Leapfrog and Vulcan geological modeling software. Block models were built with cell dimensions that were appropriate to the deposit style, orientation and dimensions of the mineralization. Selectivity during mining, mining method, equipment size and bench height were also taken into account when determining parent cell size. Sub-blocks were used to better represent volumes of thin, high-grade mineralization. All other block models intended for open pit mining were full cell models. Grade estimation was performed at the parent cell level and sub-blocks took the grades of corresponding parent blocks.
Sub-blocks were used in both underground and open pit models to better represent volumes of thin, high-grade mineralization. Grade estimation was performed at the parent cell level and sub-blocks took the grades of corresponding parent blocks. After grade estimation the sub-blocks models for open pits were re-blocked to 24 x 12 x 8 m for Subika and 12 x 12 x 8 m for the combined Apensu–Awonsu model.
For open pit resource models, where grade control information (blasthole assays) was available, the grade estimation parameters were determined through calibration against a grade–tonnage curve derived from re-blocked grade control models. For underground resource models where no grade control information was available (Apensu Deeps and Subika underground), estimation focused on minimizing conditional bias and generation of a high-quality local estimate.
The data used for the model construction were approved drill holes extracted from the GED. Data were validated using Vulcan ISIS validation tools and on-screen visualization. Issues that came out of the validation process were resolved by project geologist and corrections were sent back to the GED before a final extraction to incorporate the validated data for the geological modeling.
Geological models incorporated various combinations of lithology, structure, alteration, mineralization and metallurgical characteristics. These elements were interpreted on section and reconciled in plan. Interpretation strings were snapped to drill hole intercepts and extrapolated 25 m beyond the last section where there was no drill hole information. Where there was drill hole information that could not support the interpretation, the extrapolation is limited to half-way between sections. Intermediary strings were generated for areas with high drill hole density. Domains were modeled if they consistently occurred on three consecutive sections.
| | | | | | | | |
Date: February, 2022 | | Page 11-1 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
11.2 Exploratory Data Analysis
Exploratory data analysis made use of tools such as descriptive statistics, histograms, cumulative probability plots, box plots, and contact analysis of raw assays to guide the construction of the block model and the development of estimation plans.
Most boundaries were considered hard for mineral resource estimation purposes, except at Apensu, Awonsu and Subika open pits where some domains were combined to produce soft contacts.
11.3 Density Assignment
Specific gravity values were assigned to the combined Apensu–Awonsu block model based on oxidation surfaces interpreted by site geologists. The bottom of saprolite and the top of fresh (not oxidized) material were used to assign SG values to oxidized, partially oxidized and fresh (non-oxidized) material.
Density values were estimated into the Subika and Apensu underground models and the Subika open pit model to define local variability.
11.4 Grade Capping/Outlier Restrictions
Grade caps were determined from raw assay or composite statistics for each geology domain. In most cases, caps were determined from cumulative probability graphs of raw assays or composite, indicated correlation and verified independently by the decile or Parrish methods and/or the hi-risk approach which assesses the amounts of metal at risk in each domain.
11.5 Composites
Composite lengths vary by deposit, and range from 2–8 m, broken at geological contacts. The composites were coded for lithology, oxidation state and grade shell using the 50% rule when using MineSight software and the centroid rule when Vulcan was used for grade estimation.
11.6 Variography
Variograms were computed by lithological domain in either Sage (correlograms) or Supervisor software (correlograms/normal score transform) and were calculated in the rotated plane of the mineralization as determined from variogram contours/maps. Directional increments were used to determine principal directions in each lithological domain. The nugget effect was determined and modelled from the down the hole variograms. Usually, two spherical or exponential structures were fitted in most cases using a combination of the auto-fit option and geological interpretation. In the case of normal score transform, the final result is then back transform to original data unit.
| | | | | | | | |
Date: February, 2022 | | Page 11-2 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
11.7 Estimation/interpolation Methods
Newmont has a standardized protocol for resource modelling and estimation, which includes the following steps:
•A cross-functional model planning meeting is held to define the purpose of the Resource model;
•Data quality and suitability are verified during database extraction process;
•Appropriate geological frameworks are constructed during the geological modeling phase;
•Regular progress meetings and a handover meeting of the geological model to the Resource estimation personnel are convened. A geostatistician is involved in the geological modelling process so they have an understanding of what is being modeled;
•Exploratory data analysis is undertaken as per the relevant guidelines;
•The estimation plan is consistent with the data analysis and mineralization style, change of support is investigated and where possible the model calibrated with production data;
•Resource is classified in conformance with the Resource Classification Guideline;
•Resource risk is assessed in accordance with the Resource Risk Assessment Guideline;
•A face to face or virtual meeting and presentation is held with Mine Engineering for each Resource model released;
•Model documentation is completed in conformance with the Resource Model Documentation Guideline.
All deposits were estimated using ordinary kriging (OK) interpolation methods. Grade estimations were selective by mineralization domains in most cases and restricted within a +0.2 g/t Au grade shell.
A multi-pass search strategy (usually three passes) was used to estimate each domain. Each domain used a minimum of 1–12 samples, maximum of 10–52 samples and maximum of 2–4 samples per drill hole for the first and second passes. The search distances for these two passes used the range of the second structure of the modelled variogram, or a shorter range. A third pass was introduced with a very large search distance to estimate majority of blocks that were not estimated in the first and second passes due to limited drill data.
An outlier restriction method was employed during estimation to avoid smearing high-grade samples when estimating distant blocks.
11.8 Validation
Validation used Newmont-standard methods, which included:
•An on-screen check of geological domain assignment;
•An on-screen check of composite selections;
•An on-screen, visual inspection of OK (or inverse distance to the fifth power) blocks in plan and section and a comparison with the composite input data;
| | | | | | | | |
Date: February, 2022 | | Page 11-3 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
•A check on global grade bias by comparing the statistics of OK and nearest neighbor (NN) grade estimates, usually by domains;
•An on-screen check of model block density assignments;
•Hermitian correction (Herco) to account for change of (composite and block) support;
•Swath plots along the major dimensions of the deposits, comparing OK, inverse distance, and NN estimates together with tonnage by domains;
•Calibration to historical production for Subika open pit, Awonsu and Apensu deposits.
These validation procedures indicated that the geology and resource models used are acceptable to support mineral resource estimation.
11.9 Confidence Classification of Mineral Resource Estimate
11.9.1 Mineral Resource Confidence Classification
Resource classification parameters were based on the results of drill hole spacing studies. A drill spacing study conducted for Amoma in 2009 was used for the Subika, Apensu and Awonsu open pit mineral resource confidence classifications. A 2014 drill hole spacing study was used when generating the long-hole stoping model and a 2019 drill hole spacing study was used when generating the sublevel shrinkage model that together support the mineral resource confidence classification for Subika underground.
Mineral resource classification was undertaken based primarily on drill spacing and number of drill holes used in the estimate:
•Measured: drill spacing ranges from 12.5 x 12.5–25 x 25 m;
•Indicated: drill spacing ranges from 25 x 25–35 x 35 m;
•Inferred: drill spacing ranges from 50 x 50–70 x 70 m.
A quantitative assessment of geological risk was undertaken and applied on a block by block basis. Primary risks to resource quality include quantity and spacings of drill data, geological knowledge, geological interpretation and grade estimates. All identified risks are within acceptable tolerances with associated management plans.
11.9.2 Uncertainties Considered During Confidence Classification
Following the analysis in Chapter 11.9.1 that classified the mineral resource estimates into the measured, indicated and inferred confidence categories, uncertainties regarding sampling and drilling methods, data processing and handling, geological modelling, and estimation were incorporated into the classifications assigned. The areas with the most uncertainty were assigned to the inferred category, and the areas with fewest uncertainties were classified as measured.
A quantitative assessment of geological risk was completed using Newmont-standard methods and applied on a block-by-block basis. Primary risks to resource quality include quantity and spacings of drill data, geological knowledge, geological interpretation and grade estimates. All identified risks were within Newmont-acceptable tolerances with associated management plans.
| | | | | | | | |
Date: February, 2022 | | Page 11-4 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
11.10 Reasonable Prospects of Economic Extraction
11.10.1 Input Assumptions
For each resource estimate, an initial assessment was undertaken that assessed likely infrastructure, mining, and process plant requirements; mining methods; process recoveries and throughputs; environmental, permitting and social considerations relating to the proposed mining and processing methods, and proposed waste disposal, and technical and economic considerations in support of an assessment of reasonable prospects of economic extraction.
Mineral resources considered amenable to open pit mining methods are reported within a Lerchs–Grossmann (LG) pit shell that uses the parameters set out in Table 11-1. Variable incremental cut-off grades that range from 0.39–0.40 g/t Au in saprolite to 0.52–0.57 g/t Au in transition/fresh material were used in the inputs.
Mineral resources considered amenable to underground mining methods are reported within underground stope designs, using the parameters in Table 11-2. Variable incremental cut-off grades that range from 2.0–2.4 g/t Au were used in the inputs.
11.10.2 Commodity Price
Commodity prices used in resource estimation are based on long-term analyst and bank forecasts, supplemented with research by Newmont’s internal specialists. An explanation of the derivation of the commodity prices is provided in Chapter 16.2. The estimated timeframe used for the price forecasts is the 11-year LOM that supports the mineral reserve estimates.
11.10.3 Cut-off
The resources are reported at varying cut-off values, which are based primarily on the material type being mined, and the mining method. Process and G&A costs are based on the assumption all material is treated through the Ahafo process plant, and such costs vary by material type.
11.10.4 QP Statement
The QP is of the opinion that any issues that arise in relation to relevant technical and economic factors likely to influence the prospect of economic extraction can be resolved with further work. The mineral resource estimates are performed for deposits that are in a well-documented geological setting; the district has seen nearly two decades of active open pit operations and four years of underground mining operations conducted by Newmont; Newmont is familiar with the economic parameters required for successful operations in the Ahafo area; and Newmont has a history of being able to obtain and maintain permits, social license and meet environmental standards in Ghana. There is sufficient time in the 11-year timeframe considered for the commodity price forecast for Newmont to address any issues that may arise, or perform appropriate additional drilling, testwork and engineering studies to mitigate identified issues with the estimates.
| | | | | | | | |
Date: February, 2022 | | Page 11-5 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Table 11-1: Input Parameters, Open Pits
| | | | | | | | | | | | | | | | | | | | |
Parameters | Oxidation | Units | Subika | Awonsu | Apensu Main | Apensu South |
Gold price | | US$/oz | 1,400 | 1,400 | 1,400 | 1,400 |
Royalty rate | | % | 5 | 4 | 3 | 3 |
Royalty | | US$/oz | 70 | 56 | 42 | 42 |
Refinery and carbon handling | | US$/oz | 1.768 | 1.768 | 1.768 | 1.768 |
Discount rate | | % | 0 | 0 | 0 | 0 |
Mining cost | Saprolite | US$/t mined | 3.01 | 2.73 | 2.73 | 2.73 |
Transition + fresh rock | US$/t mined | 3.74 | 3.45 | 3.45 | 3.45 |
Mining cost incremental | Saprolite | US$/t mined/bench | 0.002 | 0.024 | 0.023 | 0.023 |
Transition + fresh rock | US$/t mined/bench | 0.002 | 0.024 | 0.023 | 0.023 |
Waste rehabilitation cost | | US$/t mined | 0.06 | 0.06 | 0.06 | 0.06 |
Process & G&A cost | Saprolite | US$/t processed | 16.20 | 16.20 | 16.20 | 16.20 |
Transition + fresh rock | US$/t processed | 20.28 | 20.40 | 20.94 | 20.48 |
Metallurgical recovery | Saprolite | % | 96 | 96 | 96 | 96 |
Transition + fresh rock | % | 91 | 83 | 84 | 84 |
Pit slope angles (IRA) | Saprolite + transition | degrees | 30 | 30 | 30 | 30 |
Fresh rock footwall | degrees | 55 | 41 | 36–48 | 36–48 |
Fresh rock hanging wall | degrees | 55 | 50 | 51 | 51 |
Cut-off grades | Saprolite | g/t Au | 0.40 | 0.39 | 0.39 | 0.39 |
Transition + fresh rock | g/t Au | 0.52 | 0.57 | 0.58 | 0.56 |
| | | | | | | | |
Date: February, 2022 | | Page 11-6 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Table 11-2: Input Parameters, Underground
| | | | | | | | | | | | | | |
Economic Parameters | Zone | Units | Apensu Deeps | Subika |
Gold price | | US$/oz | 1,400 | 1,400 |
Royalty rate | | % | 5.5 | 7.5 |
Refinery and carbon handling | | US$/oz | 1.87 | 1.87 |
Discount rate | | % | 0 | 0 |
Mining cost | | US$/t mined | 88.15 | 96.27 |
Process cost | | US$/t processed | 25.07 | 30.59 |
G&A cost | | US$/t processed | 4.07 | 3.24 |
Metallurgical recovery | Main zone | % | 90 | — |
Central zone | — | 94 |
North zone | 87 | 94 |
South zone | 90 | 94 |
Cut-off grade | | g/t Au | 2.0–2.4 | 2.8 |
Note: Metallurgical recovery figure is the percentage used in stope design and differs slightly from the LOM plan percentage assumption.
11.11 Mineral Resource Statement
Mineral resources are reported using the mineral resource definitions set out in SK1300, and are reported in situ.
Mineral resources are current as at December 31, 2021. Mineral resources are reported exclusive of those mineral resources converted to mineral reserves. Mineral resources that are not mineral reserves do not have demonstrated economic viability.
The measured and indicated mineral resource estimates for the Ahafo Operations are provided in Table 11-3. The inferred mineral resource estimates are included in Table 11-4.
| | | | | | | | |
Date: February, 2022 | | Page 11-7 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Table 11-3: Measured and Indicated Mineral Resource Statement
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Measured Mineral Resources | Indicated Mineral Resources | Measured and Indicated Mineral Resources |
Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) |
Apensu | — | — | — | 15,500 | 1.28 | 640 | 15,500 | 1.28 | 640 |
Awonsu | — | — | — | 14,200 | 1.04 | 470 | 14,200 | 1.04 | 470 |
Subika | 500 | 0.56 | 10.00 | 300 | 0.57 | 10 | 700 | 0.56 | 10 |
Open Pit Sub-Total | 500 | 0.56 | 10.00 | 30,000 | 1.16 | 1,120 | 30,500 | 1.15 | 1,130 |
Apensu Deeps | — | — | — | 14,200 | 4.02 | 1,840 | 14,200 | 4.02 | 1,840 |
Subika | — | — | — | 2,400 | 3.76 | 290 | 2,400 | 3.76 | 290 |
Underground Sub-Total | — | — | — | 16,600 | 3.99 | 2,120 | 16,600 | 3.99 | 2,120 |
Ahafo Total | 500 | 0.56 | 10.00 | 46,600 | 2.16 | 3,240 | 47,100 | 2.15 | 3,250 |
| | | | | | | | |
Date: February, 2022 | | Page 11-8 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Table 11-4: Inferred Mineral Resource Statement
| | | | | | | | | | | |
Area | Inferred Mineral Resources |
Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) |
Apensu | 3,500 | 1.4 | 150 |
Awonsu | 8,600 | 1.2 | 340 |
Subika | 1,400 | 1.8 | 80 |
Open Pit Sub-Total | 13,500 | 1.3 | 570 |
Apensu Deeps | 8,500 | 3.0 | 820 |
Subika | 2,400 | 4.6 | 350 |
Underground Sub-Total | 10,800 | 3.3 | 1,160 |
Ahafo Total | 24,300 | 2.2 | 1,730 |
Notes to Accompany Mineral Resource Tables:
1.Mineral resources are current as at December 31, 2021. Estimates are reported using the definitions in SK1300. The Qualified Person responsible for the estimate is Mr. Donald Doe, RM SME, Group Executive, Reserves, a Newmont employee.
2.The reference point for the mineral resource estimate is in situ.
3.Mineral resources are reported on a 100% basis. Newmont holds a 90% interest and the Government of Ghana has a 10% free-carried interest.
4.Mineral resources are reported exclusive of mineral reserves. Mineral resources that are not mineral reserves do not have demonstrated economic viability.
5.Mineral resources that are potentially amenable to open pit mining methods are constrained within a designed pit shell. Mineral resources that are potentially amenable to underground mining methods are constrained within conceptual stope designs. Parameters used are summarized in Table 11-1 (open pit) and Table 11-2 (underground).
6.Tonnages are metric tonnes rounded to the nearest 100,000. Gold grade is rounded to the nearest 0.01 gold grams per tonne. Gold ounces are estimates of metal contained in tonnages and do not include allowances for processing losses. Contained (cont.) gold ounces are reported as troy ounces, rounded to the nearest 10,000.
7.Rounding of tonnes and contained metal content as required by reporting guidelines may result in apparent differences between tonnes, grade and contained metal content. Due to rounding, some cells may show a zero (“0”).
8.Totals may not sum due to rounding.
| | | | | | | | |
Date: February, 2022 | | Page 11-9 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
11.12 Uncertainties (Factors) That May Affect the Mineral Resource Estimate
Areas of uncertainty that may materially impact all of the mineral resource estimates include:
•Changes to long-term metal price and exchange rate assumptions;
•Changes in local interpretations of mineralization geometry such as pinch and swell morphology, extent of brecciation, presence of unrecognized mineralization off-shoots; faults, dykes and other structures; and continuity of mineralized zones;
•Changes to geological and grade shape, and geological and grade continuity assumptions;
•Changes to unfolding, variographical interpretations and search ellipse ranges that were interpreted based on limited drill data, when closer-spaced drilling becomes available;
•Changes to metallurgical recovery assumptions;
•Changes to the input assumptions used to derive the potentially-mineable shapes applicable to the assumed underground and open pit mining methods used to constrain the estimates;
•Changes to the forecast dilution and mining recovery assumptions;
•Changes to the cut-off values applied to the estimates;
•Variations in geotechnical (including seismicity), hydrogeological and mining method assumptions;
•Changes to environmental, permitting and social license assumptions.
| | | | | | | | |
Date: February, 2022 | | Page 11-10 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
12.0 MINERAL RESERVE ESTIMATES
12.1 Introduction
Measured and indicated mineral resources were converted to mineral reserves. Mineral reserves in the Ahafo area are estimated for the Subika and Awonsu deposits, assuming open pit mining, and for Subika, assuming underground mining. Stockpiled material is also included in the mineral reserves estimates.
The Geovia Whittle pit optimization program (Whittle 4.7.3) was used to perform a Lerchs–Grossmann (LG) optimization in support of mineral reserves reporting for mineralization amenable to open pit mining methods.
A safety crown pillar of 25 m is left between the base of the Subika Phase 4 pit and the top of the Subika underground stopes. This pillar will not be mined and thus makes Phase 4 the final open pit limit for the Subika deposit.
All Inferred blocks are classified as waste in the cashflow analysis that supports mineral reserve estimation.
12.2 Open Pit Estimates
12.2.1 Pit Optimization
For mineral reserves, Newmont applies a time discount factor to the dollar value block model that is generated in the LG pit-limit analysis, to account for the fact that a pit will be mined over a period of years, and that the cost of waste stripping in the early years must bear the cost of the time value of money. In some deposits, where mineralization is uniformly distributed throughout the pit, or where the pit is shallow, discounting has little effect on the economic pit limit. For the Awonsu and Subika deposits, where upper benches contain a high percentage of the waste, and mineralization quantities and/or grade increase with depth, discounting provides a smaller pit limit upon which mine designs are based.
Pit discounting is accomplished by running the pit-limit “dollar” model through a program that discounts the dollar model values at a compound rate based on the depth of the block. In this manner, discounting is applied to future costs as well as future revenues, to represent the fact that mining proceeds from the top down within a phase.
Optimization work involved floating pit shells at a series of gold prices. The generated nested pit shells were evaluated using the mineral reserve gold price of US$1,200/oz and an 8% discount rate. The pit shells with the highest NPV were selected for detailed engineering design work.
A realistic schedule was developed in order to determine the optimal pit shell for each deposit; schedule inputs include the minimum mining width, and vertical rate of advance, mining rate and mining sequence.
Whittle analysis indicated a two-stage pit development was the best option for Awonsu, using a minimum mining width of 50 m. Mining within the Subika open pit is in the final stage with limited potential to expand at depth as a result of the underground crown pillar. No changes
| | | | | | | | |
Date: February, 2022 | | Page 12-1 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
were made to the Phase 4 pit design for Subika. The minimum mining width between the mined-out third phase of the Subika pit and the final, fourth phase, was 50 m.
12.2.2 Optimization Inputs
Operating costs for mining, processing, site and Accra administration were developed as part of the 2022 business plan (BP22) process. The costs build-up for the LOM in that plan were based on actual values as of the end of April 2021, as well as inclusion of a number of projected cost-saving measures and efficiency gains. Costs were un-escalated. Input parameters used in the constraining pit shells are summarized in Table 12-1. The costs developed as part of the LOM plan were based on a three-shovel mining fleet through to the end of the mine life. Truck and drill quantities were forecast and budgeted during the business planning process based on detailed studies. MineSight’s MSHaulage software was used to generate haulage distances and travel times based on truck field studies and site-based speed tables. The travel times were input into XERAS software, together with the mining and process schedule, to generate the required truck quantities per period. Drill quantities were forecast based on mining rates, pattern size and pit specific penetration rates.
Process costs were determined for each pit and material type (oxide and primary) using BP22 and results of internal studies. The theoretical process cost per tonne was determined for each material type from both the BP22 costs and ore feed blend.
Reclamation and closure costs were estimated from site environmental calculations.
Mine operating costs are sensitive to the cost of diesel fuel. Mineral reserves assume US$0.8861/L diesel for Brent pricing as per Newmont Corporate Guidance and account for Ghanaian taxes and local delivery. Mill operating costs are sensitive to the cost of electrical power. The mineral reserves assume a power cost of US$0.124 per kWh based on Newmont’s estimate of long-term power costs.
12.2.3 Ore Loss and Dilution
All operating pits at Ahafo South are mined on 8 m benches. The Subika model is a 24 x 12 x 8 m model to account for the 8 m mining. Block models for Awonsu, however, are produced using a 12 x 12 x 8 m block dimension to reflect the increased selectivity in ore zones.
The block models were constructed to include the expected dilution based on mining methods, bench height and other factors. The current mine and process reconciliation appears to support this assumption.
| | | | | | | | |
Date: February, 2022 | | Page 12-2 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Table 12-1: Input Parameters, Open Pits
| | | | | | | | | | | | | | |
Parameters | Oxidation | Units | Subika | Awonsu |
Gold price | | US$/oz | 1,200 | 1,200 |
Royalty rate | | % | 5 | 4 |
Royalty | | US$/oz | 70 | 56 |
Refinery and carbon handling | | US$/oz | 1.77 | 1.77 |
Discount rate | | % | 0 | 0 |
Mining cost | saprolite | US$/t mined | 3.01 | 2.73 |
transition + fresh rock | US$/t mined | 3.74 | 3.45 |
Mining cost incremental | saprolite | US$/t mined/bench | 0.002 | 0.024 |
transition + fresh rock | US$/t mined/bench | 0.002 | 0.024 |
Waste rehabilitation cost | | US$/t mined | 0.06 | 0.06 |
Process & G&A cost | saprolite | US$/t processed | 16.20 | 16.20 |
transition + fresh rock | US$/t processed | 20.28 | 20.40 |
Metallurgical recovery | saprolite | % | 96 | 96 |
transition + fresh rock | % | 91 | 83 |
Pit slope angles (IRA) | saprolite + transition | degrees | 30 | 30 |
fresh rock footwall | degrees | 55 | 41 |
fresh rock hanging wall | degrees | 55 | 50 |
12.3 Underground Estimates
12.3.1 Mining Zones
The underground mining operations are split into two areas:
•The Upper mining zone, above the 840 relative level (RL); also referred to as the upper Yoda area;
•The Central mining zone (corridor) below the 840 RL; also referred to as the Central area.
12.3.2 Stope Designs
The mine plan assumes use of a number of different mining methods including:
•Sub-level shrinkage stoping (SLS);
•Long-hole open stoping (LHOS).
Stope designs for underground operations are based on the parameters in Table 12-2. Additional input parameters to the underground mineral reserves estimate are provided in Table 12-3. Chapter 13.3 provides details on mine designs and cut-off grades.
| | | | | | | | |
Date: February, 2022 | | Page 12-3 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
A 25 m thick crown pillar will be left between the base of the Subika open pit, and the underground operations. An exclusion zone was created for the region under the final pit shape. Stopes within the exclusion zone that could not be adequately supported with additional ground support were removed from the mine plan.
Stopes were created using Deswik Stope Optimizer software at the required stope height, length and cut-off criteria based on the mine area. The stope widths depend on the stope cut-off and dilution (over-break) added to stope design, and the mining method used.
12.3.3 Ore Loss and Dilution
A stope recovery of 90% is expected in all mining areas. Dilution is projected to average 7.6%.
12.4 Stockpiles
Stockpile estimates were based on mine dispatch data; the grade comes from closely-spaced blasthole sampling and tonnage sourced from truck factors. The stockpile volumes were typically updated based on monthly surveys. The average grade of the stockpiles was adjusted based on the material balance to and from the stockpile.
Table 12-2: Design Parameters, Subika Underground
| | | | | | | | | | | |
Parameter | Unit | SLS | LHOS |
Stoping incremental cut-off | g/t Au | 2.4 | 2.9 |
Dilution hanging wall | m | 0 | 0.5 |
Dilution footwall | m | 0 | 0 |
Dilution development | % | 12 | 12 |
Stope width minimum | m | 15 | >5 |
Stope width maximum | m | 15 | 35 |
Level spacing LHOSR | m | 25 | 25 |
Min stope length | m | 15 | >15 |
Max stope length (excluding pillar) | m | 60 | 40 |
Stope-pillar extraction | % | | 0 |
Minimum pillar ratio | | | 1.3 |
Fill assumption | % | 65 | 70 |
Pillar lengths | m | | 20-35 |
Crown pillar | m | Approx 50 | Approx 30 |
Stope end wall | | | |
Footwall angle | degrees | 100 | 110 |
Hanging wall angle | degrees | 70 | 70 |
Minimum pillar between stopes | m | 0 | 20 |
Stope recovery | % | 88.9 | 88.9 |
Mill recovery | % | 94 | 94 |
| | | | | | | | |
Date: February, 2022 | | Page 12-4 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Table 12-3: Input Parameters, Subika Underground
| | | | | | | | |
Economic Parameters | Units | Values |
Gold price | US$/oz | 1200 |
Royalty rate | % | 5 |
Refinery and carbon handling | US$/oz | 1.87 |
Discount rate | % | 8 |
Mining cost | US$/t mined | 59.20 |
Process cost | US$/t processed | 14.42 |
G&A cost + site sustaining | US$/t processed | 5.85 |
Cut-off grades | g/t | 2.4–2.9 |
12.5 Commodity Prices
Commodity prices used in mineral reserve estimation are based on long-term analyst and bank forecasts, supplemented with research by Newmont’s internal specialists. The estimated timeframe used for the price forecasts is the 11-year LOM.
12.6 Mineral Reserve Statement
Mineral reserves have been classified using the mineral reserve definitions set out in SK1300. The reference point for the mineral reserve estimate is the point of delivery to the process facilities. Mineral reserves are reported on a 100% basis. The Government of Ghana has a 10% free-carried interest in the Project. Newmont has a 90% interest.
Mineral reserves are reported in Table 12-1 and are current as at December 31, 2021. Tonnages in the table are metric tonnes. Mineral reserves are reported using the mineral resource definitions set out in SK1300.
12.7 Uncertainties (Factors) That May Affect the Mineral Reserve Estimate
Areas of uncertainty that may materially impact all of the mineral reserve estimates include:
•Changes to long-term metal price and exchange rate assumptions;
•Changes to metallurgical recovery assumptions;
•Changes to the input assumptions used to derive the mineable shapes applicable to the assumed underground and open pit mining methods used to constrain the estimates;
•Changes to the forecast dilution and mining recovery assumptions;
•Changes to the cut-off values applied to the estimates;
•Variations in geotechnical (including seismicity), hydrogeological and mining method assumptions;
•Changes to environmental, permitting and social license assumptions.
| | | | | | | | |
Date: February, 2022 | | Page 12-5 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Table 12-4: Proven and Probable Mineral Reserve Statement
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Proven Mineral Reserves | Probable Mineral Reserves | Proven and Probable Mineral Reserves |
Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) |
Awonsu | — | — | — | 32,900 | 1.57 | 1,660 | 32,900 | 1.57 | 1,660 |
Subika | 11,800 | 2.35 | 890 | 6,700 | 2.19 | 480 | 18,500 | 2.29 | 1,360 |
Open Pit Sub-Total | 11,800 | 2.35 | 890 | 39,600 | 1.67 | 2,140 | 51,400 | 1.83 | 3,020 |
Subika | 9,400 | 3.76 | 1,140 | 12,700 | 2.68 | 1,100 | 22,100 | 3.14 | 2,240 |
Underground Sub-Total | 9,400 | 3.76 | 1,140 | 12,700 | 2.68 | 1,100 | 22,100 | 3.14 | 2,240 |
Stockpile Sub-total | 28,300 | 0.92 | 830 | — | — | — | 28,300 | 0.92 | 830 |
Ahafo Total | 49,500 | 1.80 | 2,860 | 52,400 | 1.92 | 3,240 | 101,800 | 1.86 | 6,090 |
Notes to Accompany Mineral Reserves Table:
1.Mineral reserves are current as at December 31, 2021. Mineral reserves are reported using the definitions in SK1300. The Qualified Person responsible for the estimate is Mr. Donald Doe, RM SME, Group Executive, Reserves, a Newmont employee.
2.The reference point for the mineral reserve estimates is the point of delivery to the process plant.
3.Mineral reserves are reported on a 100% basis. Newmont holds a 90% interest and the Government of Ghana has a 10% free-carried interest.
4.Mineral reserves that are estimated using open pit mining methods are constrained within a pit design based on an optimized Lerchs–Grossmann pit shell. Parameters used are shown in Table 12-1 for the open pit mineral reserves and Table 12-2 and Table 12-3 for the underground mineral reserves.
5.Tonnages are metric tonnes rounded to the nearest 100,000. Gold grade is rounded to the nearest 0.01 gold grams per tonne. Gold ounces are estimates of metal contained in tonnages and do not include allowances for processing losses. Contained (cont.) gold ounces are reported as troy ounces, rounded to the nearest 10,000.
6.Rounding of tonnes and contained metal content as required by reporting guidelines may result in apparent differences between tonnes, grade and contained metal content. Due to rounding, some cells may show a zero (“0”).
7.Totals may not sum due to rounding.
| | | | | | | | |
Date: February, 2022 | | Page 12-6 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
13.0 MINING METHODS
13.1 Introduction
Open pit mining is conducted using conventional techniques and an Owner-operated conventional truck and shovel fleet.
Underground mining is currently conducted using conventional stoping methods, and conventional mechanized equipment. Underground mining is conducted by a contractor.
13.2 Open Pit
13.2.1 Geotechnical Considerations
Open pit design uses defined geotechnical domains together with rock mass quality ratings for the principal lithologies and appropriate pit design criteria that reflect expected conditions and risk. Inter-ramp angles vary by deposit and pit wall lithology, and range from 30–55º. Both Newmont’s Geotechnical Engineering Department and external consultants have completed geotechnical studies and provided the geotechnical recommendations that form the basis for pit designs. A ground control management plan was developed, and is updated on an annual basis.
13.2.2 Hydrogeological Considerations
The active pits are currently mining below the water table. Pit dewatering uses a combination of perimeter and in-pit dewatering wells, in-pit sumps, and horizontal drains. A network of monitoring piezometers is installed around all of the operating pits.
13.2.3 Operations
The Surface LOM plan currently envisages mining at an average rate of approximately 26 Mt/a for nine years and peaking at 32.6 Mt/a in 2022 with a maximum rate of advance by pit stage of eight benches per annum and an average of six benches (48 m) per year. The open pit mine life will extend to 2030 with Awonsu phase 4 being the last pit. Milling will cease in 2032 after treatment of stockpiled ore. A final pit layout plan showing the pit phases for each of the open pits is provided in Figure 13-1.
Pit design assumptions include haul road widths for two-way travel of 30 m, maximum ramp grades of 10% and minimum pit-bottom widths of 30 m in deep pits as a safety measure. In selected pit-bottom benches where good grades are located, the haul road widths are reduced to 21 m wide one-way traffic to allow for maximum mining recovery.
| | | | | | | | |
Date: February, 2022 | | Page 13-1 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Figure 13-1: Final Pit Layout Plan
13.2.4 Blasting and Explosives
Production drilling and blasting for the open pits is conducted on 8 m benches with a subdrill of 1.2 m, using a 165 mm diameter bit. The pattern for production drilling is 4 x 4.5 m in both ore and waste, with powder factors varying by material type and geological conditions. Bulk
| | | | | | | | |
Date: February, 2022 | | Page 13-2 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
emulsion is loaded into both production and buffer holes; the stemming length varies according to rock type and other geologic conditions but it is generally at 3.3 m. Pre-splitting is conducted on all pit wall areas with power-split explosives supplied by the explosives provider, Orica.
The powder factor for open pits is 0.92kg/m3.
13.2.5 Grade Control
Samples from blast hole drilling in the open pit are analyzed and assay results used to generate grade control polygons that are demarcated on the ground for ore and waste zone mining. The blast hole pattern is typically 4 x 4.5 m.
13.2.6 Production Schedule
The combined open pit and underground production schedule is provided in Table 13-1.
13.2.7 Equipment
All open pit equipment is Owner-operated and owned. An equipment summary is provided in Table 13-2.
13.2.8 Personnel
The LOM personnel requirements for the open pit operations are 507 people.
13.3 Underground
13.3.1 Geotechnical Considerations
Geotechnical data collection is outlined in Chapter 7.4.
Baseline geotechnical information was used in the initial underground designs, at a time when a long-hole open stoping mining method was the preferred mining method. An improved understanding of the geotechnical setting, incorporating information on adverse in-situ stress conditions and variations in the rock mass quality, led to the selection of sublevel shrinkage stoping (SLS) in preference to long-hole open stoping.
Table 13-1: Combined Open Pit and Underground Production Schedule
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Item | Unit | Total | 2022 | 2023 | 2024 | 2025 | 2026 | 2027 | 2028 | 2029 | 2030 | 2031 | 2032 |
Material mined | M tonnes | 294 | 35 | 34 | 31 | 34 | 32 | 35 | 27 | 18 | 10 | 2 | — |
Ore processed | M tonnes | 102 | 10 | 10 | 10 | 10 | 10 | 9 | 10 | 10 | 9 | 9 | 5 |
| | | | | | | | |
Date: February, 2022 | | Page 13-3 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Table 13-2: Equipment List
| | | | | | | | |
Item/Purpose | Comment | Peak Number |
Production drills | D45KS | 7 |
Presplit drills | D560 | 3 |
Production shovels | Liebr9400 | 3 |
Haul trucks | CAT 785C | 25 |
Graders | CAT16M | 2 |
Loaders | CAT 992K&G | 5 |
The SLS mining method addresses major geotechnical risks associated with the initial long-hole open stoping mine design and the adaptation of ground control measures (such as center-out mining approach which eliminates diminishing pillars, backfilling, just-in-time development, chevron-type mining sequence, creation of stress shadows along the hanging wall, instrumentation monitoring, etc.) further improves the regional stability of the underground excavation.
A transition zone between mining methods at 450 meters below surface (mbs) was required to migrate the different stoping types.
13.3.2 Hydrogeological Considerations
Ground water inflows of approximately 40–45 L/s are predicted, and the current Subika dewatering system capacity is around 140 L/s. A 125 L/s dewatering system at the new pump station on 700 Level will serve as the main system with the 140 L/s capacity serving as a backup.
13.3.3 Operations
Mining levels are based on the mining method to be used, which varies by depth from surface (Table 13-3; Figure 13-2).
Table 13-3: Mining Methods
| | | | | | | | |
Mining Method | Interval | Comment |
Sub level shrinkage stoping (SLS) | Below 700 RL | 20 and 25 m levels. Mined using a top-down mining method. |
Long-hole open stoping (LHOS) | Above 750 RL | 25 m levels. Mined using top-down methods. |
| | | | | | | | |
Date: February, 2022 | | Page 13-4 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Figure 13-2: Example Level Layout Schematic by Mining Method
Note: Figure prepared by Newmont, 2021.
Stopes in the central mining zone, 800–700 RL, are being mined using the sub-level open stoping mining method through a set of twin spiral declines that were developed off the existing main haulage decline. Level accesses were created off the decline at 25 m intervals to intersect the ore zone.
The ore drives were driven to the extents of the defined mining corridor and stoping is being retreated from the end of the orebody towards the accesses. These stopes are being mined top-down.
The stopes were mined in panel with the maximum span up to 100 m vertical distance. Stopes were mined using a combination of longitudinal and transverse retreat methods in 25 m sublevels. A section of the mining area on the 800–750 RL will be mined in 50 m panels to increase productivity. Stopes were mucked using a combination of free and remote bogging. The ore on these levels was loaded directly from the mining extraction level to trucks or/and
| | | | | | | | |
Date: February, 2022 | | Page 13-5 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
stockpiles, hauled up through a designated(one-way) main decline to surface, and placed on the run-in-mine (RIM) pad. Surface haulage trucks transported material from the RIM pad to the process plant ROM pad.
The open stopes were backfilled with unconsolidated rock ones the stope panel was completed.
The declines were connected via a link drive that acted as a ventilation, escapeway and haulage connection between the two declines. To increase productivity, there was a one-way traffic in and out of the mine with the aid of the two declines and decline links.
Below the 725 RL, the access drive from the decline connected to a footwall drive that was offset from the ore zone by 30 m. Stope access drives were driven off the footwall drives to develop the stopes in the mineralized zone. The footwall drives were used for infrastructure to connect ventilation returns, fresh air, sumps and other infrastructure to support mining on the levels.
The second mining method being used was the SLS method. This started from the 680 RL. The mine will totally transition to the SLS mining method in a few years when the open stopes are complete, but currently, the two mining methods are being used together.
A 50 m sill pillar was established from the 750–700 RL to separate the two mining methods. The sill pillar houses infrastructure such as the 15 fill passes for backfilling and the geotechnical instrumentation monitors.
The first two levels, 680 RL and 660 RL, have 20 m sublevels and from 635 RL, the sublevels are every 25 m.
Apart from the 680 RL that is using the longitudinal mining approach, the rest of the levels are/will be mined using the transverse method. Mining commences from the center of the orebody out towards the draw point extremities, thus splitting the mining fronts into two halves. Production rings are being fired adopting the chevron mining pattern. This will ensure the mine achieves multiple mining fronts to maximize production.
A structured draw percentage strategy by level was used for the extraction of the blasted material which started from 45% draw in high-grade rings and 30% draw in low-grade rings on the 680 RL.
Current plans are to mine two sublevels concurrently due to geotechnical seismicity guidelines. Unconsolidated backfill material are introduced through the fill passes to ensure wall stability and maintain the integrity of the sill pillar. The backfill material is currently being sourced from the underground waste development headings and later, the yet to be developed waste pass from surface. The waste pass from surface will make use of the open pit WRSF material.
A final mine layout plan is provided in Figure 13-3.
13.3.4 Ventilation
The ventilation system for Subika includes refrigeration, primary and secondary fans and intake and return ventilation raises. Subika underground currently has two primary exhaust systems installed. The total mine air supply is approximately 800 m3/s.
| | | | | | | | |
Date: February, 2022 | | Page 13-6 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
13.3.5 Blasting and Explosives
The powder factor for both open stopes and the sub-level stoping ranges from 0.4–0.55 kg/t. For optimal drilling efficiency a burden of 2.8 m with ring toe spacing of 3.2 m is used for stopes. Currently the emulsion density is 1.2 g/cm3 with 403 and 406 gassers for up-holes and down-holes respectively.
13.3.6 Ore Control
Underground or control drilling is at 12.5 m and 17 m spacing for long-hole open stoping and sub-level shrinkage mining methods respectively, targeting at least two levels ahead of mining.
Full core samples generated from the ore control drilling were logged and assayed, and the resultant data together with mapping data from development headings, were used to the build geologic model, which then feeds into the block model constructed for mine production, delineating ore and waste zones in the process.
13.3.7 Production Schedule
The combined open pit and underground production schedule was provided in Table 13-1.
13.3.8 Equipment
Table 13-4 summarizes equipment requirements for the LOM plan.
13.3.9 Personnel
The mining personnel total required for underground operations is 126 persons.
| | | | | | | | |
Date: February, 2022 | | Page 13-7 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Figure 13-3: Final Underground Mine Layout Plan
Note: Figure prepared by Newmont, 2021. EMP = Emperor mining zone; YOD = Yoda mining zone; SKY = Sky mining zone. Grey blocks are mined out.
Table 13-4: Equipment Requirements, Underground
| | | | | |
Item/Purpose | Peak Number |
Drills, jumbos and bolters | 9 |
Raise borers | 2 |
Load–haul–dump vehicles | 5 |
Underground trucks | 6 |
Trucks | 7 |
Wheel loaders | 5 |
Graders | 2 |
| | | | | | | | |
Date: February, 2022 | | Page 13-8 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
14.0 RECOVERY METHOD
14.1 Process Method Selection
The process plant design was based on a combination of metallurgical testwork, previous study designs and industry standard practices for handling combinations of fresh rock and saprolite, together with debottlenecking and optimization activities once the mill was operational. The design is conventional to the gold industry and has no novel parameters.
14.2 Process Plant
A summary process flow sheet is included in Figure 14-1.
14.2.1 Plant Design
The process plant started operations in 2006 and was designed to treat 7.5 Mt/a using a blend of 27:73 oxide to primary ore. The plant was expanded in 2019 to treat an additional 3.0 Mt/a of primary ore. The planned throughput for the remaining LOM is projected to vary from 9.5–10.2 Mt/a (1.200–1,300 t/h), depending on the ore blend from the pits and underground operations.
The process route commences with one single-stage primary crushing fed by direct truck dump or front-end loader for crushing of primary ores onto a live crushed stockpile. This material is fed from the live crushed stockpile directly onto the Line 1 semi-autogenous grind (SAG) mill feed conveyor by apron feeder. An MMD-sizer is fed by front-end loader for treatment of oxide ore, which is fed directly onto the SAG mill feed conveyor.
Line 1 SAG milling is in close circuit with pebble crushers for scats or pebble crushing. Crushed pebbles scats return to the SAG mill feed conveyor. This is followed by closed-circuit ball milling to a P80 size of 106 µm for Line 1.
The Line 2 was commissioned in September 2019. The process route commences with one single-stage primary crushing fed by direct truck dump or front-end loader for crushing of primary ores onto a live crushed stockpile. This material is fed from the live crushed stockpile directly onto the Line 2 SAG mill feed conveyor by apron feeder. SAG milling is in closed circuit with pebble crusher for scats or pebble crushing. Crushed pebbles scats return to the SAG mill feed conveyor. This is followed by closed-circuit cycloning to a P80 size of 106 µm for Line 2.
The Line 1 and Line 2 cyclone overflow feed converge and through the trash screens to leach feed thickening. The thickener feed is pumped through 13 carbon-in-leach (CIL) tanks. Cyanide and oxygen are added to the thickener feed for leach with gold recovery from solution using activated carbon.
| | | | | | | | |
Date: February, 2022 | | Page 14-1 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Figure 14-1: Process Flowsheet
Note: Figure prepared by Newmont, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 14-2 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
An 18 t Anglo American Research Laboratory method (AARL) elution circuit is used to strip gold from loaded carbon. Rich solution from the elution circuit reports to the gold room rich solution tank. Electrowinning of rich solution is conducted using stainless-steel cathodes, and the sludge collected from the stainless-steel cathodes is smelted in a furnace to produce doré.
A counter-current decantation (CCD) circuit was commissioned in 2008 to recover cyanide from CIL tailings prior to discharge to the TSF. Recovered cyanide is effectively re-used in the CIL circuit and weakly acid-dissociable cyanide (CNWAD) levels in the plant tailings are effectively controlled to ensure discharge limit of 50 ppm CNWAD is not exceeded.
14.2.2 Equipment Sizing
Design criteria are summarized in Table 14-1. The plant equipment is outlined in Table 14-2.
14.3 Power and Consumables
Consumables used include reagents, and high- and low-pressure air. The main water sources for the process plant are from stored water in the mined out Apensu open pit and the TSF. Potable water is sourced from boreholes. The Line 1 installations require approximately 30 MW of power to operate at full capacity while Line 2 draws about 15 MW of power. The site has an emergency backup generation plant consisting of seven 3.9 MW high-speed GE generators that together are capable of producing about 27.3 MW of supplemental power.
14.4 Personnel
The process personnel required for the LOM plan total 251 persons. This count includes both operations and maintenance staff.
| | | | | | | | |
Date: February, 2022 | | Page 14-3 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Table 14-1: Design Criteria
| | | | | | | | | | | |
| Units | Saprolite | Primary |
Plant capacity | Mt/a | 0.42 | 9.5 |
Head grade (design) | Au g/t | 0.65 | 1.87 |
Design gold recovery | % | 95.0 | 92 |
Crushing plant availability | % | 92 | 92 |
Mill/CIL availability | % | 93 | 93 |
Bond abrasion index (Ai) | | 0.34–0.83 | 0.34–0.83 |
Bond ball mill work index (BWi) | kWh/t | 17.4–19.2 | 17.4–19.2 |
Grind size (P80) | μm | 106 | 106 |
Installed mill power (SAG + ball) | kW | 26,000 | 26,000 |
Number of CIL tanks | | 13 | 13 |
Total CIL volume | m3 | 42,250 | 42,250 |
Calculated CIL residence time | h | 20.7 | 20.7 |
Cyanide consumption | kg/t | 0.24 | 0.24 |
Quicklime consumption | kg/t | 3.44 | 0.9 |
Elution circuit type | | AARL | AARL |
Elution circuit size | t | 18.0 | 18.0 |
Frequency of elution | strips/week | 7.0 | 7.0 |
| | | | | | | | |
Date: February, 2022 | | Page 14-4 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Table 14-2: Plant Equipment
| | | | | |
Number/Qty | Details of Specification |
2 | 54-inch x 74-inch gyratory crusher with 500 kW installed motors power |
1 | MMD 154 series twin-shaft 4-tooth x 9 ring sizer with 2 x 150 kW installed motor power |
2 | 10.36 m x 5.0 m EGL SAG mill with 2 x 650 kW installed motor power |
2 | 3.6-m x 7.3-m double deck pebble dewatering screen, top deck -33 mm x 66 mm, bottom deck 10 mm x 36 mm panels |
2 | MP 800 pebble crusher, one duty, one standby, each with 600 kW installed motor power for line 1 |
2 | HP 400 pebble crusher, one duty, one standby, each with 315 kW installed motor power for line 2 |
1 | 7.31 m x 11.90 m EGL ball mill with 2 x 650 kW installed motor power |
12 | 26” Krebs cyclones for line 1 |
12 | 20” Krebs cyclones for line 2 |
3 | 3.6 m x 6.1 m cyclone overflow trash screen, two duty, one standby, screen aperture- 0.7 mm x 12 mm, 37 kW 4-pole motor, DF 504S exciters |
1 | 42 m pre-leach thickener |
13 | 3,250 m3 leach and adsorption tanks |
13 | Lightning agitators, 783 gearbox, A310 shaft and impellers |
1 | 1.8 m x 4.8 m carbon recovery screen, screen aperture; 1.1 mm x 12 mm |
2 | 3.6 m x 6.1 m carbon safety screen, one duty, one standby, screen aperture 1.1 mm x 12 mm, 30 kW 4-pole electric motor, DF 501S exciters |
2 | 42 m CCD thickeners |
1 | 1.2 m x 3.6 m carbon dewatering screen, screen aperture 0.7 mm x 12 mm |
1 | 18 t acid wash column |
1 | 18 t elution column |
2 | 6,000 amp electrowinning cells |
1 | TA 300D Barring furnace |
1 | 900 kg/hr diesel-fired carbon regeneration kiln |
Note: EGL = effective grinding length, CCD = counter-current decant.
| | | | | | | | |
Date: February, 2022 | | Page 14-5 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
15.0 INFRASTRUCTURE
15.1 Introduction
Key infrastructure associated with the Ahafo Operations includes:
•Completed open pit mines at Apensu and Amoma; the Apensu open pit is being used for water storage;
•Open pit mines at Awonsu and Subika;
•An underground mine at Subika;
•Five waste rock storage facilities (WRSFs); two active, and three inactive;
•Five stockpiles;
•Process plant;
•TSF;
•Water storage facility;
•Reverse osmosis water treatment facility;
•Sediment control structures;
•Residential camp;
•Mine accommodations village;
•Various support facilities including truck and vehicle shops, warehouse, administration, contractor and temporary offices, fuel storage, core processing facilities at the mine site, clinic and emergency response facilities, gatehouse, mess facilities, change rooms, personnel training facilities, information technology (IT) communications setups and towers, environmental monitoring facilities, water treatment plants, sewage treatment plants, reagents shed, and plant nurseries.
During the remainder of the LOM, a new WRSF for storage of waste from the Apensu area will be required, as will a second water treatment plant.
An infrastructure layout plan showing the surface infrastructure layout was provided in Figure 13-1.
15.2 Roads and Logistics
Road access is outlined in chapter 4.2. Mine supplies are brought in by truck.
15.3 Stockpiles
A stockpiling strategy is practiced to defer lower-grade ores to the end of mine life. All stockpile inventories are calculated and reported monthly. Inventories are based on truck counts of material added to and removed from stockpiles, multiplied by truck tonnage factors.
| | | | | | | | |
Date: February, 2022 | | Page 15-1 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
15.4 Waste Rock Storage Facilities
WRSFs are sited on hillsides as bank fills or within shallow drainages as complete valley fills and were sited 60–100 m from pit crests. Lift heights are typically planned at 16–20 m and the overall slopes are designed at 3:1.
The Apensu, Subika West and Amoma WRSFs are complete, and will have no additional waste tonnage added. The LOM plan assumes that only two WRSFs, at Subika East and Awonsu, will be active for the remainder of the mine life:
•Subika East: overall approximate capacity of 197 Mt, mine plan will send 195 Mt of waste to the facility;
•Awonsu: facility will be expanded to the northwest; overall approximate capacity of 170 Mt; mine plan will send 163 Mt of waste to the facility.
15.5 Tailings Storage Facilities
The TSF is constructed in the Subri stream drainage. The northern upstream embankment serves as a downstream dam for a water storage facility. The TSF is operated as a zero-discharge facility; all water is returned to the process facility for reuse. The main embankment has been constructed in stages.
The TSF is monitored monthly with both a network of piezometers to determine phreatic water levels in the embankments as well as via settlement pins. Drone survey and pool volume measurements are also conducted on monthly basis. These data are tabulated in a report that is reviewed by both Newmont and the Engineer of Record with Jones and Wagner, a third-party consultant. Reporting follows the TSF operations, maintenance and surveillance (OMS) management plan which stipulates minimum monitoring requirements and triggers that require a further response.
Permitted capacities meet the required capacities for the present LOM. A raise to Cell 1 will allow operations to 2029; a raise to Cell 2, planned for 2030, will support the operations to the end of the LOM. The two TSF expansions, Cell 1 that would be expanded to a maximum capacity of 190 Mt and a newly constructed 50 Mt capacity Cell 2, and an associated 300 m water storage facility buffer require resettlement of a number of families within the facility footprints.
15.6 Water Management Structures
Water management infrastructure at Ahafo South for mine operations include the following:
•Surface water management infrastructure: diversion channels around the pits and collection systems downstream of the WRSFs and stockpiles;
•Pit runoff management infrastructure: in-pit and ex-pit sumps with a system centrifugal pumps and high-density polyethylene (HDPE) pipelines dewatering to holding and transfer ponds;
•Groundwater management infrastructure: hybrid system of ex-pit dewatering wells and installations of arrays of horizontal drain holes.
| | | | | | | | |
Date: February, 2022 | | Page 15-2 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
A reverse osmosis water treatment plant with a 50 L/s (feed) capacity was commissioned in August 2017. A second reverse osmosis water treatment plant is planned for execution in 2024, based on the current business plan BP22 and will have an additional 50 L/s (feed) capacity.
As part of the Ahafo water strategy an impacted water pond is also planned for execution in 2022, with commissioning in 2023.
15.7 Water Supply
Process water is sourced from a cross-valley embankment dam upstream from the TSF, which impounds water from a 28 km2 area of the Subri stream watershed. Potable water for the mining operations and camps is produced from bore fields.
Water supplies are sufficient for current and planned development needs. The Ahafo mine operates with an excess water balance resulting from the accumulation of seasonal rainfall contacting the mining operation. The excess is stored in the mined-out Apensu pit, which has an area of 350,000 m2.
15.8 Camps and Accommodation
Two types of accommodation are available. Camp A, originally the construction camp at the plant site, hosts about 300 people, consisting of site visitors and long-term employees. Newmont constructed the Mensah Kumtah Village, near Kenyasi, for expatriate families and Ghanaian management staff. Workers who do not live in company housing receive housing allowances.
15.9 Power and Electrical
Newmont Africa in Ghana receives power purchased from the Volta River Authority’s (VRA) electricity generation thermal facilities near the Ghanaian coast and at the Akosombo Dam hydroelectric facility.
Power is delivered to Ahafo South via GRIDCO’s 161 kV transmission line into the Ahafo (Kenyasi) Substation where voltage is dropped from 161 kV down to 11 kV for use at the Ahafo complex. GRIDCO currently has three 161 kV lines that deliver power to the Kenyasi Substation at Ahafo; two from Kumasi, and one from Kumasi via Techiman/Sunyani. Each transmission line is capable of delivering power sufficient to satisfy Ahafo’s current peak startup power demand of about 35 MW, as the capacity of each of these lines is approximately 120 MW. The two direct lines from Kumasi do not have additional power demand other than Newmont’s load at the Kenyasi substation. The third line (from Kumasi via Sunyani) supplies Techiman, then Sunyani, on its route to service Kenyasi substation.
Newmont has also installed emergency power generating capacity, consisting of 27 MW at Ahafo South to meet any power challenges.
| | | | | | | | |
Date: February, 2022 | | Page 15-3 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
16.0 MARKET STUDIES AND CONTRACTS
16.1 Markets
Newmont has established contracts and buyers for the doré products from the Ahafo Operations, and has an internal corporate marketing group that monitors markets for its key products. Together with public documents and analyst forecasts, these data support that there is a reasonable basis to assume that for the LOM plan, that the key products will be saleable at the assumed commodity pricing.
There are no agency relationships relevant to the marketing strategies used.
Product valuation is included in the economic analysis in Chapter 19, and is based on a combination of the metallurgical recovery, commodity pricing, and consideration of processing charges.
The doré is not subject to product specification requirements.
16.2 Commodity Price Forecasts
Newmont uses a combination of historical and current contract pricing, contract negotiations, knowledge of its key markets from a long operations production record, short-term versus long-term price forecasts prepared by Newmont’s internal corporate marketing group, public documents, and analyst forecasts when considering long-term commodity price forecasts.
Higher metal prices are used for the mineral resource estimates to ensure the mineral reserves are a sub-set of, and not constrained by, the mineral resources, in accordance with industry-accepted practice.
The long-term commodity price and exchange rate forecasts are:
Mineral reserves:
•Gold: US$1,200/oz;
•US$:Gh$: 5.75.
Mineral resources:
•Gold: US$1,400/oz;
•US$:Gh$: 5.75.
16.3 Contracts
Newmont’s doré is sold on the spot market, by marketing experts retained in-house by Newmont. The terms contained within the sales contracts are typical and consistent with standard industry practice and are consistent with doré sold from other Newmont operations.
The largest in-place contracts other than for product sales cover items such as bulk commodities, operational and technical services, mining and process equipment, and administrative support services. Contracts are negotiated and renewed as needed. Contract terms are typical of similar contracts in Ghana.
| | | | | | | | |
Date: February, 2022 | | Page 16-1 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
17.0 ENVIRONMENTAL STUDIES, PERMITTING, AND PLANS, NEGOTIATIONS, OR AGREEMENTS WITH LOCAL INDIVIDUALS OR GROUPS
17.1 Introduction
Newmont is committed to design, develop, and operate the Ahafo Operations in a manner that will preserve human health, the environment and stakeholder relationships. A variety of environmental management activities were developed and are being implemented during all operational phases. Newmont’s intent is to eliminate, offset, or reduce to acceptable levels any adverse environmental impacts through management programs, resource-specific mitigation measures, monitoring plans, and implementation schedules.
17.2 Baseline and Supporting Studies
Baseline and supporting environmental studies were completed to assess both pre-existing and ongoing site environmental conditions, as well as to support decision-making processes during operations start-up. Characterization studies were completed for climate, air quality, hydrology and surface water quality, hydrogeology, flora, fauna, soils, agriculture and land use, and the socioeconomic environment.
Plans were developed and implemented to address aspects of operations such as waste and fugitive dust management, spill prevention and contingency planning, water management, and noise levels.
17.3 Environmental Considerations/Monitoring Programs
Procedures for operational environmental and social monitoring of the Ahafo Operations area were established to ensure mining activities have minimal or acceptable levels of impact to surrounding areas. The primary environmental resource monitored at Ahafo is water – both surface water and groundwater. Other resource monitoring being conducted by Newmont includes fugitive dust, point source emission, meteorological parameters, noise and vibration, revegetation progress, surface water run-off quantity and quality, mine pit conditions, waste rock disposal, TSF decant water quantity and quality, and environmental geochemistry of ore, waste rock and tailings. Data from these monitoring programs are used to evaluate potential impacts of mining operations and to continually update plans for long-term monitoring and reclamation.
17.4 Closure and Reclamation Considerations
In 2003, Newmont developed a conceptual closure and reclamation plan for the Ahafo South Mine Project Environmental Impact Statement (EIS) (SGS 2004) in compliance with requirements of the Environmental Protection Agency (EPA). The EIS was approved by the EPA in April 2005. A Draft Reclamation Plan to begin the process of formalizing the conceptual plan presented in the EIS was undertaken later in 2005. The Draft Reclamation Plan, subsequently approved for implementation, included descriptions of mining and ore processing operations,
| | | | | | | | |
Date: February, 2022 | | Page 17-1 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
WRSFs, TSF, water-related structures, and the reclamation and monitoring plans for these facilities.
Under EPA requirements, Newmont is required to provide updates to the reclamation plan as mine development proceeds. These updates are to include revisions or modifications to the closure and reclamation plan necessary to address actual site conditions. An updated Closure and Reclamation Plan was developed in 2019 that covers closure of the Subika Underground and ancillary infrastructure as well as the prior existing facilities.
A Reclamation Security Agreement (RSA) between the EPA and Newmont was signed in April 2008 to outline the various objectives and targets as guidance for the plan.
The EPA requires a Reclamation Bond to be posted as part of any mine permitting process. The bond is required to provide financial surety against non-compliance under the approved Closure and Reclamation Plan and is required within six months after the start of operations.
As part of the reclamation and security agreement (environmental bond) with the Ghanaian Government, Newmont has provided a cumulative (project to date) cash deposit of US$12.66 M.
The closure cost estimate used in the economic analysis in Chapter 19 is US$0.2 B.
17.5 Permitting
All major permits and approvals are in place to support operations. Where permits have specific terms, renewal applications are made of the relevant regulatory authority as required, prior to the end of the permit term. The environmental permitting approach for the operations is based on Ghana’s EPA Environmental Impact Assessment (EIA) process and meets Newmont policy requirements and social and environmental standards.
Newmont monitors the regulatory regime in place at each of its operations and ensures that all permits are updated in line with any regulatory changes.
17.6 Social Considerations, Plans, Negotiations and Agreements
Newmont developed a public consultation and disclosure plan (PCDP) for the Ahafo Operations using guidelines and policies developed by the International Finance Corporation (IFC). The IFC requires public consultation as an on-going process to be conducted during the construction and operational phases of any project.
Newmont has well-established relationships, issue management approaches, engagement forums, and a suite of integrated social impact and opportunity-aligned strategic investment partnerships.
Newmont understands and accepts the importance of proactive community relations as an overriding principle in its day-to-day operations as well as future development planning. The company therefore structures its community relations activities to consider the concerns of the local people and endeavors to communicate and demonstrate its commitment in terms that can be best appreciated and understood to maintain the social license to operate.
| | | | | | | | |
Date: February, 2022 | | Page 17-2 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
17.7 Qualified Person’s Opinion on Adequacy of Current Plans to Address Issues
Based on the information provided to the QP by Newmont (see Chapter 25), there are no material issues known to the QP. The Ahafo Operations are mature mining operations and currently has the social license to operate within its local communities.
| | | | | | | | |
Date: February, 2022 | | Page 17-3 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
18.0 CAPITAL AND OPERATING COSTS
18.1 Introduction
Capital and operating cost estimates are at a minimum at a pre-feasibility level of confidence, having an accuracy level of ±25% and a contingency range not exceeding 15%.
18.2 Capital Cost Estimates
Capital costs are based on recent prices or operating data. Capital costs include funding for infrastructure, pit dewatering, development drilling, and permitting as well as miscellaneous expenditures required to maintain production. Mobile equipment re-build/replacement schedules and fixed asset replacement and refurbishment schedules are included. Sustaining capital costs reflect current price trends.
The overall capital cost estimate for the LOM is US$0.5 B, as summarized in Table 18-1.
18.3 Operating Cost Estimates
Operating costs are based on actual costs seen during operations and are projected through the LOM plan. Historical costs are used as the basis for operating cost forecasts for supplies and services unless there are new contract terms for these items. Labor and energy costs are based on budgeted rates applied to headcounts and energy consumption estimates.
Operating costs for the LOM are estimated at US$3.5 B, as summarized in Table 18-2. The estimated LOM open pit mining cost is US$2.57/t and the underground mining cost is US$52.27/t. Base processing costs are estimated at US$11.84 /t. In addition, total G&A costs are estimated at US$5.15/t.
Table 18-1: Capital Cost Estimate
| | | | | | | | |
Area | Unit | Value |
Mining, open pit | US$ B | 0.2 |
Mining, underground | US$ B | 0.2 |
Process | US$ B | 0.1 |
Total | US$ B | 0.5 |
Note: numbers have been rounded; totals may not sum due to rounding.
Table 18-2: Operating Cost Estimate
| | | | | | | | |
Area | Unit | Value |
Mining, open pit | US$ B | 0.6 |
Mining, underground | US$ B | 1.2 |
Process | US$ B | 1.2 |
G&A | US$ B | 0.5 |
Total | US$ B | 3.5 |
Note: numbers have been rounded; totals may not sum due to rounding.
| | | | | | | | |
Date: February, 2022 | | Page 18-1 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
19.0 ECONOMIC ANALYSIS
19.1 Methodology Used
The financial model that supports the mineral reserve declaration is a standalone model that calculates annual cash flows based on scheduled ore production, assumed processing recoveries, metal sale prices and Gh$/US$ exchange rate, projected operating and capital costs and estimated taxes.
The financial analysis is based on an after-tax discount rate of 8%. All costs and prices are in unescalated “real” dollars. The currency used to document the cash flow is US$.
All costs are based on the 2022 budget. Revenue is calculated from the recoverable metals and long-term metal price and exchange rate forecasts.
19.2 Financial Model Parameters
The economic analysis is based on the metallurgical recovery predictions in Chapter 10.4, the mineral reserve estimates in Chapter 13, the mine plan discussed in Chapter 14, the commodity price forecasts in Chapter 16, closure cost estimates in Chapter 17.4, and the capital and operating costs outlined in Chapter 18. Royalties were summarized in Chapter 3.9.
Taxes are based on Newmont’s existing agreement with the government of Ghana.
The economic analysis is based on 100% equity financing and is reported on a 100% project ownership basis. The economic analysis assumes constant prices with no inflationary adjustments.
The NPV8% is $1.2 B. As the cashflows are based on existing operations where all costs are considered sunk to 1 January 2022, considerations of payback and internal rate of return are not relevant.
A summary of the financial results is provided in Table 19-1. An annualized cashflow statement is provided in Table 19-2. In these tables, EBITDA = earnings before interest, taxes, depreciation and amortization. The active mining operation ceases in 2032; however, closure costs are estimated to 2036.
19.3 Sensitivity Analysis
The sensitivity of the Project to changes in metal prices, exchange rate, sustaining capital costs and operating cost assumptions was tested using a range of 25% above and below the base case values (Figure 19-1).
The Project is most sensitive to metal price changes, less sensitive to changes in operating costs, and least sensitive to changes in capital costs.
The sensitivity to gold grade mirrors the sensitivity to the gold price and is not shown.
| | | | | | | | |
Date: February, 2022 | | Page 19-1 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Table 19-1: Cashflow Summary Table
| | | | | | | | |
Item | Unit | Value |
Metal prices |
Gold | US$/oz | 1,200 |
Mined ore |
Tonnage | M tonnes | 102 |
Gold grade | g/t | 1.86 |
Gold ounces | Moz | 6.1 |
Capital costs | US$B | 0.5 |
Costs applicable to sales | US$B | 4.2 |
Discount rate | % | 8 |
Exchange rate | United States dollar:Ghanaian cedi (USD:GHS) | 5.75 |
Free cash flow | US$B | 1.5 |
Net present value | US$B | 1.2 |
Note: Numbers have been rounded; totals may not sum due to rounding. Table 19-1 contains “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, which are intended to be covered by the safe harbor created by such sections and other applicable laws. Please refer to the note regarding forward-looking information at the front of the Report. The cash flow is only intended to demonstrate the financial viability of the Project. Investors are cautioned that the above is based upon certain assumptions which may differ from Newmont’s long-term outlook or actual financial results, including, but not limited to commodity prices, escalation assumptions and other technical inputs. For example, Table 19-1 uses the price assumptions stated in the table, including a gold commodity price assumption of US$1,200/oz, which varies significantly from current gold prices and the assumptions that Newmont uses for its long-term guidance. Please be reminded that significant variation of metal prices, costs and other key assumptions may require modifications to mine plans, models, and prospects.
| | | | | | | | |
Date: February, 2022 | | Page 19-2 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Table 19-2: Annualized Cashflow (2022–2036)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Item | Units | Total | 2022 | 2023 | 2024 | 2025 | 2026 | 2027 | 2028 | 2029 | 2030 | 2031 | 2032 | 2033 | 2034 | 2035 | 2036 |
Material mined | M tonnes | 294.4 | 35.1 | 34.2 | 31.4 | 34.2 | 31.9 | 34.8 | 26.6 | 18.0 | 10.3 | 1.6 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
Ore processed | M tonnes | 101.9 | 10.3 | 9.8 | 9.8 | 9.8 | 9.6 | 9.4 | 9.8 | 9.8 | 9.5 | 8.9 | 5.2 | 0.0 | 0.0 | 0.0 | 0.0 |
Contained gold, processed | Moz | 6.1 | 0.7 | 0.8 | 0.9 | 0.5 | 0.5 | 0.5 | 0.5 | 0.6 | 0.5 | 0.4 | 0.1 | 0.0 | 0.0 | 0.0 | 0.0 |
Processed ore gold grade | g/t | 1.86 | 2.04 | 2.55 | 2.80 | 1.68 | 1.60 | 1.66 | 1.72 | 2.03 | 1.68 | 1.30 | 0.86 | — | — | — | — |
Recovered gold | Moz | 5.6 | 0.6 | 0.7 | 0.8 | 0.5 | 0.5 | 0.5 | 0.5 | 0.6 | 0.5 | 0.3 | 0.1 | — | — | — | — |
Recovery, gold | % | 92 | 92 | 93 | 93 | 92 | 92 | 92 | 91 | 90 | 90 | 89 | 85 | 0 | 0 | 0 | 0 |
Net revenue | US$ billion | 6.7 | 0.7 | 0.9 | 1.0 | 0.6 | 0.5 | 0.6 | 0.6 | 0.7 | 0.6 | 0.4 | 0.1 | 0.0 | 0.0 | 0.0 | 0.0 |
Costs applicable to sales | US$ billion | -4.2 | -0.5 | -0.5 | -0.5 | -0.4 | -0.4 | -0.4 | -0.4 | -0.4 | -0.3 | -0.3 | -0.1 | 0.0 | 0.0 | 0.0 | 0.0 |
Other expenses | US$ billion | 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 | 0.0 | 0.0 | 0.0 |
EBITDA | US$ billion | 2.5 | 0.3 | 0.4 | 0.5 | 0.2 | 0.1 | 0.1 | 0.2 | 0.3 | 0.2 | 0.1 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
Operating cash flow (after estimated taxes and other adjustments) | US$ billion | 2.0 | 0.3 | 0.4 | 0.4 | 0.1 | 0.2 | 0.1 | 0.2 | 0.2 | 0.2 | 0.0 | 0.0 | -0.1 | 0.0 | 0.0 | 0.0 |
Total capital | US$ billion | -0.5 | -0.1 | -0.1 | -0.1 | -0.1 | -0.1 | -0.1 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
Free cash flow | US$ billion | 1.5 | 0.2 | 0.3 | 0.4 | 0.0 | 0.1 | 0.0 | 0.2 | 0.2 | 0.1 | 0.0 | 0.0 | -0.1 | 0.0 | 0.0 | 0.0 |
Note: Numbers have been rounded; totals may not sum due to rounding. EBITDA = earnings before interest, taxes, depreciation and amortization. Table 19-2 contains “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, which are intended to be covered by the safe harbor created by such sections and other applicable laws. Please refer to the note regarding forward-looking information at the front of the Report. The cash flow is only intended to demonstrate the financial viability of the Project. Investors are cautioned that the above is based upon certain assumptions which may differ from Newmont’s long-term outlook or actual financial results, including, but not limited to commodity prices, escalation assumptions and other technical inputs. For example, Table 19-2 uses the price assumptions stated in the table, including a gold commodity price assumption of US$1,200/oz, which varies significantly from current gold prices and the assumptions that Newmont uses for its long-term guidance. Please be reminded that significant variation of metal prices, costs and other key assumptions may require modifications to mine plans, models, and prospects.
| | | | | | | | |
Date: February, 2022 | | Page 19-3 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Figure 19-1: NPV Sensitivity
Note: Figure prepared by Newmont, 2021. FCF = free cashflow; op cost = operating cost; cap cost = capital cost; NPV = net present value.
| | | | | | | | |
Date: February, 2022 | | Page 19-4 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
20.0 ADJACENT PROPERTIES
This Chapter is not relevant to this Report.
| | | | | | | | |
Date: February, 2022 | | Page 20-1 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
21.0 OTHER RELEVANT DATA AND INFORMATION
This Chapter is not relevant to this Report.
| | | | | | | | |
Date: February, 2022 | | Page 21-1 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
22.0 INTERPRETATION AND CONCLUSIONS
22.1 Introduction
The QP notes the following interpretations and conclusions, based on the review of data available for this Report.
22.2 Property Setting
The Ahafo Operations are located in an area that has more than 15 years of mining activity. As a result, local and regional infrastructure and the supply of goods available to support mining operations is well-established. Personnel with experience in mining-related activities are available in the district. There are excellent transportation routes that access the Ahafo area.
There are no significant topographic or physiographic issues that would affect the Ahafo Operations. The Ahafo Operations area consists primarily of subsistence farms with small-scale commercial farming intermingled with areas of forest regrowth and remnants of secondary forest. The Project shares a boundary with the Bosumkese Forest Reserve, and the Amoma Shelterbelt Forest Reserve bisects the Ahafo mining lease.
Mining operations are conducted year-round.
22.3 Ownership
The Project is held through Newmont Ghana Gold Ltd., an indirectly-wholly owned Newmont subsidiary. The Government of Ghana has a 10% free-carried interest in the Ahafo Operations.
22.4 Mineral Tenure, Surface Rights, Water Rights, Royalties and Agreements
Newmont currently holds three mining licenses, and nine prospecting licenses that in total cover an area of 952 km2. The mining leases are current until 2031 and can be renewed by negotiation. The total area held under mining licenses is approximately 549 km2.
Newmont holds sufficient surface rights to execute the LOM plan.
Newmont holds permits to allow abstraction of groundwater, surface water, and water from the Tano River.
The Agreement between Newmont and the Government of Ghana defines and fixes, in specific terms, the effective corporate tax and royalty burden the Project (including Ahafo South and Ahafo North) will carry during operations. The Agreement establishes a fixed fiscal and legal regime, including sliding-scale royalty and tax rates for the duration of the Agreement’s stability period.
A 2% NSR is payable on all ounces produced from the Rank (formerly Ntotroso) concession to Franco Nevada. The majority of the Subika deposit, the northern portion of the Awonsu deposit, and the southern tip of the Amoma deposit fall within the Rank mining lease boundary.
| | | | | | | | |
Date: February, 2022 | | Page 22-1 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
22.5 Geology and Mineralization
The Ahafo deposits are interpreted to be examples of orogenic gold deposits;
The geological understanding of the settings, lithologies, and structural and alteration controls on mineralization in the different zones is sufficient to support estimation of mineral resources and mineral reserves. The geological knowledge of the area is also considered sufficiently acceptable to reliably inform mine planning.
The mineralization style and setting are well understood and can support declaration of mineral resources and mineral reserves.
Newmont continues to actively explore in the immediate and near-mine areas.
22.6 History
The Ahafo Operations have over 15 years of active mining history, and exploration activities date back to 1989 when gold was first discovered.
22.7 Exploration, Drilling, and Sampling
The exploration programs completed to date are appropriate for the style of the mineralization within the Ahafo Operations area.
Drill holes are oriented with an inclination to accommodate the steeply-dipping nature of the Ahafo deposits, resulting in an intersection generally representing 75–85% of true width. Drilling is orientated generally perpendicular to the strike of the orebodies. Local variations may be present to accommodate infrastructure constraints.
Sampling methods, sample preparation, analysis and security conducted prior to Newmont’s interest in the operations were in accordance with exploration practices and industry standards at the time the information was collected. Current Newmont sampling methods are acceptable for mineral resource and mineral reserve estimation. Sample preparation, analysis and security for the Newmont programs are currently performed in accordance with exploration best practices and industry standards.
The quantity and quality of the lithological, geotechnical, collar and down-hole survey data collected during the exploration and delineation drilling programs are sufficient to support mineral resource and mineral reserve estimation. The collected sample data adequately reflect deposit dimensions, true widths of mineralization, and the style of the deposits. Sampling is representative of the gold and copper grades in the deposit, reflecting areas of higher and lower grades.
Density measurements are considered to provide acceptable density values for use in mineral resource and mineral reserve estimation.
The sample preparation, analysis, quality control, and security procedures used by the Ahafo Operations have changed over time to meet evolving industry practices. Practices at the time the information was collected were industry-standard, and frequently were industry-leading practices. The sample preparation, analysis, quality control, and security procedures are
| | | | | | | | |
Date: February, 2022 | | Page 22-2 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
sufficient to provide reliable data to support estimation of mineral resources and mineral reserves.
The QA/QC programs adequately address issues of precision, accuracy and contamination. Modern drilling programs typically included blanks, duplicates and standard samples. QA/QC submission rates meet industry-accepted standards.
22.8 Data Verification
Newmont had data collection procedures in place that included several verification steps designed to ensure database integrity. Newmont staff also conducted regular logging, sampling, laboratory and database reviews. In addition to these internal checks, Newmont contracted independent consultants to perform laboratory, database and mine study reviews. The process of active database quality control and internal and external audits generally resulted in quality data.
The data verification programs concluded that the data collected from the Ahafo Operations area adequately support the geological interpretations and constitute a database of sufficient quality to support the use of the data in mineral resource and mineral reserve estimation.
Data that were verified on upload to the database are acceptable for use in mineral resource and mineral reserve estimation.
The QP receives and reviews monthly reconciliation reports from the mine site. Through the review of these reconciliation factors the QP is able to ascertain the quality and accuracy of the data and its suitability for use in the assumptions underlying the mineral resource and mineral reserve estimates.
22.9 Metallurgical Testwork
Industry-standard studies were performed as part of process development and initial mill design. Subsequent production experience and focused investigations guided mill alterations and process changes. Testwork programs, both internal and external, continue to be performed to support current operations and potential improvements. From time to time, this may lead to requirements to adjust cut-off grades, modify the process flowsheet, or change reagent additions and plant parameters to meet concentrate quality, production, and economic targets.
Samples selected for testing were representative of the various types and styles of mineralization. Samples were selected from a range of depths within the deposit. Sufficient samples were taken so that tests were performed on sufficient sample mass.
Recovery factors estimated are based on appropriate metallurgical testwork, and are appropriate to the mineralization types and the selected process routes. The forecast LOM gold recovery varies by deposit, ranging from 81–94%. These forecasts do not include the application of recovery degradation to long-term stockpiles.
The mill throughput and associated recovery factors are considered appropriate to support mineral resource and mineral reserve estimation, and mine planning.
The Ahafo Operations produce clean ores containing low levels of problematic elements.
| | | | | | | | |
Date: February, 2022 | | Page 22-3 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
22.10 Mineral Resource Estimates
Newmont has a set of protocols, internal controls, and guidelines in place to support the mineral resource estimation process, which the estimators must follow.
Estimation was performed by Newmont personnel. All mineralogical information, exploration boreholes and background information were provided to the estimators by the geological staff at the mines or by exploration staff. Modelling and resource estimates were performed in Vulcan software.
Mineral resources are reported using the mineral resource definitions set out in SK1300, and are reported exclusive of those mineral resources converted to mineral reserves. The reference point for the estimate is in situ. Mineral resources are reported on a 100% basis. The Government of Ghana has a 10% free-carried interest in the Project. Newmont has a 90% interest.
Factors that may affect the mineral resource estimate include: changes to long-term metal price assumptions; changes in local interpretations of mineralization geometry and continuity of mineralized zones; changes to geological and grade shape and geological and grade continuity assumptions; changes to input parameters used in the pit shells and stope outlines constraining the mineral resources; changes to the cut-off grades used to constrain the estimates; variations in geotechnical, mining, and processing recovery assumptions; and changes to environmental, permitting and social license assumptions.
22.11 Mineral Reserve Estimates
Mineral reserves were converted from measured and indicated mineral resources. Inferred mineral resources were set to waste. Estimation was performed by Newmont personnel.
All current mineral reserves will be exploited using open pit mining methods, underground mining methods, or are in stockpiles. Mineral reserves amenable to open pit mining methods were estimated assuming open pit methods with conventional methods for drilling, blasting, loading with hydraulic shovels and haulage by large trucks. Mineral reserves amenable to underground mining methods were estimated assuming conventional stoping methods. Mineral resources were converted to mineral reserves using a detailed mine plan, an engineering analysis, and consideration of appropriate modifying factors. Modifying factors include the consideration of dilution and ore losses, open pit and underground mining methods, metallurgical recoveries, permitting and infrastructure requirements.
Mineral reserves are reported using the mineral resource definitions set out in SK1300. The reference point for the estimate is the point of delivery to the process facilities. Mineral reserves are reported on a 100% basis. The Government of Ghana has a 10% free-carried interest in the Project. Newmont has a 90% interest.
Factors that may affect the mineral reserve estimates include: changes to the gold price assumptions; changes in the metallurgical recovery factors; changes to the operating cut-off assumptions for mill feed or stockpile feed; changes to the input assumptions used to derive the open pit and stope outlines and the mine plan that is based on those open pit and stope designs; changes to operating, and capital assumptions used, including changes to input cost assumptions such as consumables, labor costs, royalty and taxation rates; variations in
| | | | | | | | |
Date: February, 2022 | | Page 22-4 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
geotechnical, hydrogeological, dilution and mining assumptions; including changes to pit phase or stope designs as a result of changes to geotechnical, hydrogeological, and engineering data used; changes to the assumed permitting and regulatory environment under which the mine plan was developed; ability to maintain mining permits and/or surface rights; ability to permit the expanded TSF and obtain the operations certificate for current and future underground operations; ability to maintain social and environmental license to operate.
22.12 Mining Methods
Mining operations can be conducted year-round.
Open pit mining is conducted using conventional techniques and an Owner-operated conventional truck and shovel fleet. The open pit mine plans are appropriately developed to maximize mining efficiencies, based on the current knowledge of geotechnical, hydrological, mining and processing information on the Project.
Underground mining is currently conducted using conventional stoping methods, and conventional mechanized equipment. Underground mining is conducted by a contractor. The underground mine plans are based on the current knowledge of geotechnical, hydrological, mining and processing information in the Subika underground area.
The open pit LOM plan currently envisages mining at an average rate of approximately 26 Mt/a for nine years and peaking at 32.15 Mt/a in 2022 with a maximum rate of advance by pit stage of eight benches per annum and an average of six benches (48 m) per year. The mine life will extend to 2030 with material mined from the open pit. Milling will cease in 2032 after treatment of stockpiled ore.
The underground LOM plan currently envisages a production rate of 2.43 Mt/a for an eight-year period, with underground mining ending in 2030.
As part of day-to-day operations, Newmont will continue to perform reviews of the mine plan and consider alternatives to, and variations within, the plan. Alternative scenarios and reviews may be based on ongoing or future mining considerations, evaluation of different potential input factors and assumptions, and corporate directives.
22.13 Recovery Methods
The process plant design was based on a combination of metallurgical testwork, previous study designs, previous operating experience. The design is conventional to the gold industry and has no novel parameters.
The plant will produce variations in recovery due to the day-to-day changes in ore type or combinations of ore type being processed. These variations are expected to trend to the forecast recovery value for monthly or longer reporting periods.
22.14 Infrastructure
The majority of the key infrastructure to support the mining activities envisaged in the LOM is in place.
A stockpiling strategy is practiced to defer lower-grade ores to the end of mine life.
| | | | | | | | |
Date: February, 2022 | | Page 22-5 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
The LOM plan assumes that only two WRSFs, at Subika East and Awonsu, will be active for the remainder of the mine life.
The TSF is operated as a zero-discharge facility; all water is returned to the process facility for reuse. Permitted capacities meet the required capacities for the present LOM. A raise to Cell 1 will allow operations to 2029; a raise to Cell 2, planned for 2030, will support the operations to the end of the LOM. The two TSF expansions, Cell 1 that would be expanded to a maximum capacity of 190Mt and a newly constructed 50 Mt capacity Cell 2, and an associated 300 m water storage facility buffer require resettlement of a number of families within the facility footprints.
The existing infrastructure, staff availability, existing power, water, and communications facilities, and the methods whereby goods are transported to the mine are all in place and well-established, and can support the estimation of mineral resources and mineral reserves.
Personnel commute from surrounding settlements or live in purpose-built accommodation villages.
Water management infrastructure for mine operations includes pit runoff, surface water and groundwater management infrastructure. A reverse osmosis water treatment plant is operational.
Power is sourced from the Volta River Authority’s electricity generation thermal facilities. Three 161 kV lines feed into the Kenyasi Substation at Ahafo. Each transmission line is capable of delivering power sufficient to satisfy Ahafo’s current peak startup power demand of about 35 MW, as the capacity of each of these lines is approximately 120 MW. Newmont has installed emergency generating capacity.
22.15 Market Studies
Newmont has established contracts and buyers for its doré products, and has an internal marketing group that monitors markets for its key products. Together with public documents and analyst forecasts, there is a reasonable basis to assume that for the LOM plan, the doré will be saleable at the assumed commodity pricing.
Newmont’s doré is sold on the spot market, by marketing experts retained in-house by Newmont. The terms contained within the sales contracts are typical and consistent with standard industry practice, and are similar to contracts for the supply of doré elsewhere in the world.
Newmont uses a combination of historical and current contract pricing, contract negotiations, knowledge of its key markets from a long operations production record, short-term versus long-term price forecasts prepared by Newmont’s internal marketing group, public documents, and analyst forecasts when considering long-term commodity price forecasts. Higher metal prices are used for the mineral resource estimates to ensure the mineral reserves are a sub-set of, and not constrained by, the mineral resources, in accordance with industry-accepted practice.
The largest in-place contracts other than for product sales cover items such as bulk commodities, operational and technical services, mining and process equipment, and administrative support services. Contracts are negotiated and renewed as needed. Contract terms are typical of similar contracts in Ghana.
| | | | | | | | |
Date: February, 2022 | | Page 22-6 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
22.16 Environmental, Permitting and Social Considerations
Baseline and supporting environmental studies were completed to assess both pre-existing and ongoing site environmental conditions, as well as to support decision-making processes during operations start-up. Characterization studies were completed for climate, air quality, hydrology and surface water quality, hydrogeology, flora, fauna, soils, agriculture and land use, and the socioeconomic environment.
Plans were developed and implemented to address aspects of operations such as waste and fugitive dust management, spill prevention and contingency planning, water management, and noise levels.
The key monitoring areas are surface water and ground water. Other resource monitoring being conducted by Newmont includes fugitive dust, point source emission, meteorological parameters, noise and vibration, revegetation progress, surface water run-off quantity and quality, mine pit conditions, waste rock disposal, TSF decant water quantity and quality, and environmental geochemistry of ore, waste rock and tailings.
The EPA requires a Reclamation Bond to be posted as part of any mine permitting process. The bond is required to provide financial surety against non-compliance under the approved Closure and Reclamation Plan and is required within six months after the start of operations. As part of the reclamation and security agreement (environmental bond) with the Ghanaian Government, Newmont has provided a cumulative (project to date) cash deposit of US$12.66 M. The closure cost estimate used in the economic analysis in Chapter 19 is US$0.2 B.
All major permits and approvals are either in place or Newmont expects to obtain them in the normal course of business. Where permits have specific terms, renewal applications are made of the relevant regulatory authority as required, prior to the end of the permit term.
Newmont has well-established relationships, engagement forums, and a suite of integrated social impact and opportunity-aligned strategic investment partnerships. Newmont understands and accepts the importance of proactive community relations as an overriding principle in its day-to-day operations as well as future development planning. The company therefore structures its community relations activities to consider the concerns of the local people and endeavors to communicate and demonstrate its commitment in terms that can be best appreciated and understood to maintain the social license to operate
22.17 Capital Cost Estimates
Capital costs were based on recent prices or operating data and are at a minimum at a pre-feasibility level of confidence, having an accuracy level of ±25% and a contingency range not exceeding 15%.
Capital costs included funding for infrastructure, pit dewatering, development drilling, and permitting as well as miscellaneous expenditures required to maintain production. Mobile equipment re-build/replacement schedules and fixed asset replacement and refurbishment schedules were included. Sustaining capital costs reflected current price trends.
The overall capital cost estimate for the LOM is US$0.5 B.
| | | | | | | | |
Date: February, 2022 | | Page 22-7 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
22.18 Operating Cost Estimates
Operating costs were based on actual costs seen during operations and are projected through the LOM plan, and are at a minimum at a pre-feasibility level of confidence, having an accuracy level of ±25% and a contingency range not exceeding 15%.
Historical costs were used as the basis for operating cost forecasts for supplies and services unless there are new contract terms for these items. Labor and energy costs were based on budgeted rates applied to headcounts and energy consumption estimates.
Operating costs for the LOM are estimated at US$3.5 B. The estimated LOM open pit mining cost is $2.57/t and the underground mining cost is $52.27/t. Base processing costs are estimated at $11.84 /t. In addition, total G&A costs are estimated at $5.15/t.
22.19 Economic Analysis
The NPV8% is $1.2 B. As the cashflows are based on existing operations where all costs are considered sunk to 1 January 2022, considerations of payback and internal rate of return are not relevant.
22.20 Risks and Opportunities
Factors that may affect the mineral resource and mineral reserve estimates were identified in Chapter 11.13 and Chapter 12.9 respectively.
22.20.1 Risks
The risks associated with the Ahafo Operations are generally those expected with open pit and underground mining operations and include the accuracy of the resource model, unexpected geological features that cause geotechnical issues, and/or operational impacts.
Other risks noted include:
•The mineral reserve estimates are sensitive to metal prices. Lower metal prices than forecast in the LOM plan may require revisions to the mine plan, with impacts to the mineral reserve estimates and the economic analysis that supports the mineral reserve estimates;
•Labor cost increases or productivity decreases could also impact the stated mineral reserves and mineral resources;
•Geotechnical and hydrological assumptions used in mine planning are based on historical performance, and to date historical performance has been a reasonable predictor of current conditions. Any changes to the geotechnical and hydrological assumptions could affect mine planning, affect capital cost estimates if any major rehabilitation is required due to a geotechnical or hydrological event, affect operating costs due to mitigation measures that may need to be imposed, and impact the economic analysis that supports the mineral reserve estimates;
•Expectations as to the performance of the Subika underground mining method;
| | | | | | | | |
Date: February, 2022 | | Page 22-8 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
•Proposed community resettlement as part of the TSF planning for the LOM. There is a risk that this can be achieved with stakeholder approval and within the timelines anticipated and budgets allocated;
•Galamsey (artisanal mining) activity can impact mine safety and operations;
•Changes in climate could result in drought and associated potential water shortages that could impact operating costs and ability to operate;
•Political risk from challenges to mining licenses and/or Newmont’s right to operate.
22.20.2 Opportunities
Opportunities include:
•Conversion of some or all of the measured and indicated mineral resources currently reported exclusive of mineral reserves to mineral reserves, with appropriate supporting studies;
•Upgrade of some or all of the inferred mineral resources to higher-confidence categories, such that such better-confidence material could be used in mineral reserve estimation;
•Higher metal prices than forecast could present upside sales opportunities and potentially an increase in predicted Project economics;
•Potential for new underground operations proximal to the current mineral resource and mineral reserve estimates, with the support of additional studies.
22.21 Conclusions
Under the assumptions presented in this Report, the Ahafo Operations have a positive cash flow, and mineral reserve estimates can be supported.
| | | | | | | | |
Date: February, 2022 | | Page 22-9 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
23.0 RECOMMENDATIONS
As the Ahafo Operations are operating mines, the QP has no material recommendations to make.
| | | | | | | | |
Date: February, 2022 | | Page 23-1 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
24.0 REFERENCES
24.1 Bibliography
Allen, L.E., 2018: Subika OP Resource Model Peer Review: draft internal Newmont memorandum, March 30, 2018, 2 p.
Amec Foster Wheeler, 2016: Ahafo South Operations, Ghana Reserve/Resource Audit Report; 15 September 2016, report prepared by Amec Foster Wheeler for Newmont, Project No. 189766, 252 p.
Anderson, T., 2018: Ahafo North Stage 2B Feasibility Report: internal Newmont report, 2 January, 2018, 563 p.
Baah-Danso, E., 2011: The Structural Evolution of the Subika Deposit, Ahafo, Sefwi Belt, Ghana: MSc thesis, University of Western Australia.
Bawden W.F., 2018: Preliminary Subika Extraction Ratio Guidance: memorandum prepared for Newmont by Bawden Engineering Ltd, 29 October, 2018, 14 p.
Bawden W.F., 2018: Subika Underground Project 2018 Geotechnical Review: report prepared for Newmont by Bawden Engineering Ltd, 27 December, 2018, 44 p.
Boye, A., Anderson, T., Jessen, M.H., Weedon, P., Nii-Armah, R., and Kappes, R., 2017: Ahafo North Competent Person Report: internal Newmont report, 31 December 2017, 48 p.
Canadian Institute of Mining, Metallurgy and Petroleum (CIM), 2019: Estimation of Mineral Resources and Mineral Reserves, Best Practice Guidelines: Canadian Institute of Mining, Metallurgy and Petroleum, November, 2019.
Canadian Institute of Mining, Metallurgy and Petroleum (CIM), 2014: CIM Definition Standards for Mineral Resources and Mineral Reserves: Canadian Institute of Mining, Metallurgy and Petroleum, May, 2014.
Canadian Securities Administrators (CSA), 2011: National Instrument 43-101, Standards of Disclosure for Mineral Projects, Canadian Securities Administrators.
Golder Associates (Accra), 2014a: Newmont Ahafo North Project, Ghana, Open Pit Slope Stage 2a Design – Susuan, Techire, and Subenso South Pits: report prepared by Golder for Newmont, July 2014 (Golder Project # 11613856).
Golder Associates (Accra), 2014b. Newmont Ahafo North Project, Ghana, Geotechnical Design of Yamfo NE and Subenso North Pits: report prepared by Golder for Newmont, July 2014 (Golder Project # 13614907).
Goldfarb, R.J., Baker, T., Dube, B., Groves, D.I., Hart, C.J R. and Gosselin, P., 2005: Distribution, Characters and Genesis of Gold Deposits in Metamorphic Terranes: Economic Geology 100th Anniversary Volume, Society of Economic Geologists, Littleton, Colorado, USA, pp. 407–450.
Groves, D.I., Goldfarb, R.J., Gebre-Mariam, M., Hagemann, S.G., and Robert, F. 1998: Orogenic gold deposits: A Proposed Classification in the Context of their Crustal Distribution and Relationship to Other Gold Deposit Types: Ore Geology Review, Special Issue, Vol. 13, pp. 7–27.
| | | | | | | | |
Date: February, 2022 | | Page 24-1 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Groves, D.I., Goldfarb, R.J., Robert, F., and Hart, C.J.R., 2003: Gold Deposits in Metamorphic Belts: Overview of Current Understanding, Outstanding Problems, Future Research, and Exploration Significance: Economic Geology, Vol. 98, pp. 1–29.
Inglis, R., 2015: Ahafo North Database Audit 2015: internal Newmont report, 29 May 2015, 41 p.
Jewbali, A., 2018: Review of the 2018 Subika UG model (Only Inclusion of SA1 material): internal Newmont memorandum, February 2018, 5 p.
Kappes, R., 2018: Ahafo South Recovery Upscale Factor Testwork and Analysis: internal Newmont report, January 2018, 13 p.
Kappes, R., 2018: Ahafo South Strategy Finer Grind Processing Options Update: internal Newmont report, January 2018, 37 p.
Kintzel, R., 2016: HOV – Cut-off Grade Strategy: internal Newmont report, 6 January 2016, 2 p.
Martos, M., 2017: GED Database Audit, Ghana Drillholes Database: internal Newmont report, 23 March, 2017, 59 p.
McFarlane, H., 2017: The Geodynamic and Tectonic Evolution of the Palaeoproterozoic Sefwi Greenstone Belt, West African Craton (Ghana): PhD thesis, Monash University, Australia and Université Toulouse 3 Paul Sabatier, France, 326 p.
Moritz, R., 2000: What Have We Learnt About Orogenic Lode Gold Deposits Over The Past 20 Years? : article posted to University of Geneva, Switzerland, website, 7 p. accessed 8 February 2010, http://www.unige.ch/sciences/terre/mineral/publications/onlinepub/moritz_gold_brgm_2000.doc.
Newmont, 2015a. Final Ahafo North Stage 2B Metallurgical Report: internal Newmont report prepared by Metallurgical Services for the Ahafo North Project Team, August 2015.
Newmont, 2015b: Ahafo North Mine Engineering Stage 2AB Bridge Report: internal Newmont report, August 28, 2015.
Newmont, 2016: NI 43-101 Technical Report for Ahafo Operations, Ghana: internal Newmont report, 6 July 2017, 197 p.
Newmont, 2017: Subika Phase 3 and Phase 4 Pit Wall Optimization Geotechnical Study: internal Newmont report, 2 October, 2017, 27 p.
Newmont, 2018a: Competent Person Report, Ahafo (Geology): draft internal Newmont report: 26 October, 2018, 16 p.
Newmont, 2018b: Competent Person Report, Ahafo (Metallurgy): draft internal Newmont report: 24 December, 2018, 20 p.
Newmont, 2018c: Competent Person Report, Ahafo (Open Pit Mine Engineering) 14 November, 2018, 17 p.
Newmont, 2018d: Competent Person Report, Ahafo (Apensu): draft internal Newmont report: 24 October, 2018, 18 p.
Newmont, 2018e: Competent Person Report, Ahafo (Resource Modelling): draft internal Newmont report: 24 December, 2018, 12 p.
| | | | | | | | |
Date: February, 2022 | | Page 24-2 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
Newmont, 2019: Competent Person Report, Ahafo (Underground): draft internal Newmont report, 20 January, 2019, 54 p.
NewFields Mining and Energy Services, 2014a: Groundwater Modeling and Dewatering Study, Model Update to Well Installation and Aquifer Testing at Yamfo Northeast and Subenso North Deposits, Ahafo North Project, Ghana, West Africa: report prepared by NewFields for Newmont Ghana Gold, Ltd., April 2014.
NewFields Mining and Energy Services, 2014b: Subenso North and Yamfo Northeast Hydrogeologic Characterization and Dewatering Evaluation, Well Installation and Hydraulic Testing Report, Ahafo North Project, Ghana, West Africa: report prepared by NewFields for Newmont Ghana Gold Ltd., January 2014.
NewFields Mining and Energy Services, 2015a: Preliminary Water Balance Model Results, Ahafo North: report prepared by NewFields for Newmont Ghana Gold, Ltd., May 4, 2015
NewFields Mining and Energy Services, 2015b: Tailings Storage Facility and Water Storage Dam Impoundment Engineering Design Report, Ahafo North Gold Project, Stage 2B: report prepared by NewFields for Newmont Ghana Gold, Ltd.
NewFields Mining and Energy Services, 2015c: Plant Site Soil and Foundation Recommendations, Ahafo North Gold Project, Stage 2B, Brong Ahafo Region, Ghana: report prepared by NewFields for Newmont Ghana Gold, Ltd.
NewFields Mining and Energy Services, 2016a: Surface Water Management Infrastructure Design Report, Ahafo North Project, Stage 2B: report prepared by NewFields for Newmont Ghana Gold, Ltd.
NewFields Mining and Energy Services, 2016b: Life-of-Mine Water Management Plan, Ahafo North Project, Brong Ahafo Region, Ghana: report prepared by NewFields for Newmont Ghana Gold, Ltd.
Optiro, 2014: Newmont Ghana Gold Limited Subika July 2014 Mineral Resource Independent Audit: report prepared by Optiro Pty Ltd for Newmont, 2 October, 2014, 59 p.
Seibel, G., 2016: Mineral Resource/Mineral Reserve Audit Input: report prepared by Amec Foster Wheeler for Newmont, 7 November, 2016, 47 p.
Seibel, G., 2015: Resource Model Review, Ahafo North: report prepared by AMEC for Newmont, 27 August, 2015, 321 p.
Seibel, G., 2012: Ahafo North Resource Audit Ghana: report prepared by AMEC for Newmont, Project No. 170934, November 30, 2012, 120 p.
| | | | | | | | |
Date: February, 2022 | | Page 24-3 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
24.2 Abbreviations and Symbols
| | | | | |
Abbreviation/Symbol | Term |
AARL | Anglo American Research Laboratory |
AAS | atomic absorption spectrometry |
Ai | abrasion index |
AMS | African Mining Services |
AUGNG | Ahafo Unified Ghanaian National Grid |
BLY | Boart Longyear |
BRGM | Bureau Recherché Geologiques et Minieres |
Bwi | Bond work index |
CCD | counter-current decantation |
CIL | carbon-in-leach |
CIM | Canadian Institute of Mining, Metallurgy and Petroleum |
CNwad | weakly acid-dissociable cyanide |
DTM | digital terrain model |
EIA | Environmental Impact Assessment |
EIS | Environmental Impact Statement |
EMP | Environmental Management Plan |
EPA | Environmental Protection Agency |
G&A | general and administrative |
GED | Global Exploration Database |
Gencor | Gencor Ltd |
GPS | global positioning system |
Herco | Hermitian correction |
ICP-MS | inductively coupled plasma–mass spectrometry |
IFC | International Finance Corporation |
IP | induced polarization |
IRA | inter-ramp angle |
La Source | La Source Compagnie Miniere SAS |
LHOSR | long-hole open stope retreat |
LOM | life-of-mine |
LOMP | life-of-mine plan |
LVB | Land Valuation Board |
MFZ | “Magic Fracture Zone” |
MSPU | Mobile Sample Preparation Unit |
NewFields | NewFields Consultants Inc. |
Newmont | Newmont Corporation |
NGGL | Newmont Ghana Gold Ltd. |
NGRL | Newmont Golden Ridge Ltd. |
NN | nearest neighbor |
Normandy | Normandy Mining Limited |
NPV | net present value |
NSR | net smelter return |
OK | ordinary kriging |
PCDP | public consultation and disclosure plan |
PoO | Plan of Operations |
QA/QC | Quality assurance and quality control |
| | | | | | | | |
Date: February, 2022 | | Page 24-4 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
| | | | | |
Abbreviation/Symbol | Term |
QP | Qualified Person |
RAB | rotary air blast |
Rank | Rank Mining Company Limited |
RAR | return air raise |
RC | reverse circulation |
RL | Relative level |
RQD | rock quality description |
SAG | semi-autogenous grind |
SG | Specific gravity |
SLOS | Sublevel open stoping |
SME | Society for Mining, Metallurgy and Exploration |
TDEM | total domain electromagnetics |
TEM | transient electromagnetic |
TSF | tailing storage facility |
US | United States |
VL | Visual Logger |
VLF | very low frequency |
VRA | Volta River Authority |
24.3 Glossary of Terms
| | | | | |
Term | Definition |
adit | A passageway or opening driven horizontally into the side of a hill generally for the purpose of exploring or otherwise opening a mineral deposit. An adit is open to the atmosphere at one end, a tunnel at both ends. |
amphibolite facies | one of the major divisions of the mineral-facies classification of metamorphic rocks, the rocks of which formed under conditions of moderate to high temperatures (500° C, or about 950° F, maximum) and pressures. Amphibole, diopside, epidote, plagioclase, almandine and grossular garnet, and wollastonite are minerals typically found in rocks of the amphibolite facies |
aquifer | A geologic formation capable of transmitting significant quantities of groundwater under normal hydraulic gradients. |
azimuth | The direction of one object from another, usually expressed as an angle in degrees relative to true north. Azimuths are usually measured in the clockwise direction, thus an azimuth of 90 degrees indicates that the second object is due east of the first. |
ball mill | A piece of milling equipment used to grind ore into small particles. It is a cylindrical shaped steel container filled with steel balls into which crushed ore is fed. The ball mill is rotated causing the balls themselves to cascade, which in turn grinds the ore. |
Bond work index (BWi) | A measure of the energy required to break an ore to a nominal product size, determined in laboratory testing, and used to calculate the required power in a grinding circuit design. |
carbon-in-leach (CIL) | A method of recovering gold and silver from fine ground ore by simultaneous dissolution and adsorption of the precious metals onto fine carbon in an agitated tank of ore solids/solution slurry. The carbon flows counter currently to the head of the leaching circuit. |
| | | | | | | | |
Date: February, 2022 | | Page 24-5 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
| | | | | |
Term | Definition |
comminution/crushing/grinding | Crushing and/or grinding of ore by impact and abrasion. Usually, the word "crushing" is used for dry methods and "grinding" for wet methods. Also, "crushing" usually denotes reducing the size of coarse rock while "grinding" usually refers to the reduction of the fine sizes. |
concentrate | The concentrate is the valuable product from mineral processing, as opposed to the tailing, which contains the waste minerals. The concentrate represents a smaller volume than the original ore |
counter-current decantation (CCD) | A process where a slurry is thickened and washed in multiple stages, where clean water is added to the last thickener, and overflows from each thickener are progressively transferred to the previous thickener, countercurrent to the flow of thickened slurry. |
crosscut | A horizontal opening driven across the course of a vein or structure, or in general across the strike of the rock formation; a connection from a shaft to an ore structure. |
crown pillar | An ore pillar at the top of an open stope left for wall support and protection from wall sloughing above |
cut-off grade | A grade level below which the material is not “ore” and considered to be uneconomical to mine and process. The minimum grade of ore used to establish reserves. |
data verification | The process of confirming that data has been generated with proper procedures, has been accurately transcribed from the original source and is suitable to be used for mineral resource and mineral reserve estimation |
decline | A sloping underground opening for machine access from level to level or from the surface. Also called a ramp. |
density | The mass per unit volume of a substance, commonly expressed in grams/ cubic centimeter. |
development | Often refers to the construction of a new mine or; Is the underground work carried out for the purpose of reaching and opening up a mineral deposit. It includes shaft sinking, cross-cutting, drifting and raising. |
dilution | Waste of low-grade rock which is unavoidably removed along with the ore in the mining process. |
easement | Areas of land owned by the property owner, but in which other parties, such as utility companies, may have limited rights granted for a specific purpose. |
electrowinning. | The removal of precious metals from solution by the passage of current through an electrowinning cell. A direct current supply is connected to the anode and cathode. As current passes through the cell, metal is deposited on the cathode. When sufficient metal has been deposited on the cathode, it is removed from the cell and the sludge rinsed off the plate and dried for further treatment. |
elution | Recovery of the gold from the activated carbon into solution before zinc precipitation or electro-winning. |
encumbrance | An interest or partial right in real property which diminished the value of ownership, but does not prevent the transfer of ownership. Mortgages, taxes and judgements are encumbrances known as liens. Restrictions, easements, and reservations are also encumbrances, although not liens. |
feasibility study | A feasibility study is a comprehensive technical and economic study of the selected development option for a mineral project, which includes detailed assessments of all applicable modifying factors, as defined by this section, together with any other relevant operational factors, and detailed financial analysis that are necessary to demonstrate, at the time of reporting, that extraction is economically viable. The results of the study may serve as the basis for a final decision by a proponent or financial institution to proceed with, or finance, the development of the project. A feasibility study is more comprehensive, and with a higher degree of accuracy, than a pre-feasibility study. It must contain mining, infrastructure, and process designs completed with sufficient rigor to serve as the basis for an investment decision or to support project financing. |
flowsheet | The sequence of operations, step by step, by which ore is treated in a milling, concentration, or smelting process. |
footwall | The wall or rock on the underside of a vein or ore structure. |
| | | | | | | | |
Date: February, 2022 | | Page 24-6 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
| | | | | |
Term | Definition |
gravity separation | Exploitation of differences in the densities of particles to achieve separation. Machines utilizing gravity separation include jigs and shaking tables. |
greenschist facies | one of the major divisions of the mineral facies classification of metamorphic rocks, the rocks of which formed under the lowest temperature and pressure conditions usually produced by regional metamorphism. Temperatures between 300 and 450 °C (570 and 840 °F) and pressures of 1 to 4 kilobars are typical. The more common minerals found in such rocks include quartz, orthoclase, muscovite, chlorite, serpentine, talc, and epidote |
hanging wall | The wall or rock on the upper or top side of a vein or ore deposit. |
indicated mineral resource | An 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 term adequate geological evidence means evidence that is sufficient to establish geological and grade or quality continuity with reasonable certainty. 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. |
inferred mineral resource | An 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 term limited geological evidence means evidence that is only sufficient to establish that geological and grade or quality continuity is more likely than not. 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. A qualified person must have a reasonable expectation that the majority of inferred mineral resources could be upgraded to indicated or measured mineral resources with continued exploration; and should be able to defend the basis of this expectation before his or her peers. |
initial assessment | An initial assessment is a preliminary technical and economic study of the economic potential of all or parts of mineralization to support the disclosure of mineral resources. The initial assessment must be prepared by a qualified person and must include appropriate assessments of reasonably assumed technical and economic factors, together with any other relevant operational factors, that are necessary to demonstrate at the time of reporting that there are reasonable prospects for economic extraction. An initial assessment is required for disclosure of mineral resources but cannot be used as the basis for disclosure of mineral reserves |
IP | Geophysical method, induced polarization; used to directly detect scattered primary sulfide mineralization. Most metal sulfides produce IP effects, e.g., chalcopyrite, bornite, chalcocite, pyrite, pyrrhotite |
life of mine (LOM) | Number of years that the operation is planning to mine and treat ore, and is taken from the current mine plan based on the current evaluation of ore reserves. |
lithogeochemistry | The chemistry of rocks within the lithosphere, such as rock, lake, stream, and soil sediments |
measured mineral resource | A 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 term conclusive geological evidence means evidence that is sufficient to test and confirm geological and grade or quality continuity. 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 this section, in sufficient detail to support detailed mine planning and final evaluation of the economic viability of the deposit. |
mill | Includes any ore mill, sampling works, concentration, and any crushing, grinding, or screening plant used at, and in connection with, an excavation or mine. |
| | | | | | | | |
Date: February, 2022 | | Page 24-7 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
| | | | | |
Term | Definition |
mineral reserve | A 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. The determination that part of a measured or indicated mineral resource is economically mineable must be based on a preliminary feasibility (pre-feasibility) or feasibility study, as defined by this section, conducted by a qualified person applying the modifying factors to indicated or measured mineral resources. Such study must demonstrate that, at the time of reporting, extraction of the mineral reserve is economically viable under reasonable investment and market assumptions. The study must establish a life of mine plan that is technically achievable and economically viable, which will be the basis of determining the mineral reserve. The term economically viable means that the qualified person has determined, using a discounted cash flow analysis, or has otherwise analytically determined, that extraction of the mineral reserve is economically viable under reasonable investment and market assumptions. The term investment and market assumptions includes all assumptions made about the prices, exchange rates, interest and discount rates, sales volumes, and costs that are necessary to determine the economic viability of the mineral reserves. The qualified person must use a price for each commodity that provides a reasonable basis for establishing that the project is economically viable. |
mineral resource | A 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. The term material of economic interest includes mineralization, including dumps and tailings, mineral brines, and other resources extracted on or within the earth’s crust. It does not include oil and gas resources, gases (e.g., helium and carbon dioxide), geothermal fields, and water. When determining the existence of a mineral resource, a qualified person, as defined by this section, must be able to estimate or interpret the location, quantity, grade or quality continuity, and other geological characteristics of the mineral resource from specific geological evidence and knowledge, including sampling; and conclude that there are reasonable prospects for economic extraction of the mineral resource based on an initial assessment, as defined in this section, that he or she conducts by qualitatively applying relevant technical and economic factors likely to influence the prospect of economic extraction. |
mine take area | Area for which land holders have been fully compensated for moving from their land. |
net present value (NPV) | The present value of the difference between the future cash flows associated with a project and the investment required for acquiring the project. Aggregate of future net cash flows discounted back to a common base date, usually the present. NPV is an indicator of how much value an investment or project adds to a company. |
net smelter return royalty (NSR) | A defined percentage of the gross revenue from a resource extraction operation, less a proportionate share of transportation, insurance, and processing costs. |
open pit | A mine that is entirely on the surface. Also referred to as open-cut or open-cast mine. |
open stope | In competent rock, it is possible to remove all of a moderate sized ore body, resulting in an opening of considerable size. Such large, irregularly-shaped openings are called stopes. The mining of large inclined ore bodies often requires leaving horizontal pillars across the stope at intervals in order to prevent collapse of the walls. |
ounce (oz) (troy) | Used in imperial statistics. A kilogram is equal to 32.1507 ounces. A troy ounce is equal to 31.1035 grams. |
overburden | Material of any nature, consolidated or unconsolidated, that overlies a deposit of ore that is to be mined. |
| | | | | | | | |
Date: February, 2022 | | Page 24-8 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
| | | | | |
Term | Definition |
plant | A group of buildings, and especially to their contained equipment, in which a process or function is carried out; on a mine it will include warehouses, hoisting equipment, compressors, repair shops, offices, mill or concentrator. |
preliminary feasibility study, pre-feasibility study | A preliminary feasibility study (prefeasibility study) is a comprehensive study of a range of options for the technical and economic viability of a mineral project that has advanced to a stage where a qualified person has determined (in the case of underground mining) a preferred mining method, or (in the case of surface mining) a pit configuration, and in all cases has determined an effective method of mineral processing and an effective plan to sell the product. A pre-feasibility study includes a financial analysis based on reasonable assumptions, based on appropriate testing, about the modifying factors and the evaluation of any other relevant factors that are sufficient for a qualified person to determine if all or part of the indicated and measured mineral resources may be converted to mineral reserves at the time of reporting. The financial analysis must have the level of detail necessary to demonstrate, at the time of reporting, that extraction is economically viable |
probable mineral reserve | A probable mineral reserve is the economically mineable part of an indicated and, in some cases, a measured mineral resource. For a probable mineral reserve, the qualified person’s confidence in the results obtained from the application of the modifying factors and in the estimates of tonnage and grade or quality is lower than what is sufficient for a classification as a proven mineral reserve, but is still sufficient to demonstrate that, at the time of reporting, extraction of the mineral reserve is economically viable under reasonable investment and market assumptions. The lower level of confidence is due to higher geologic uncertainty when the qualified person converts an indicated mineral resource to a probable reserve or higher risk in the results of the application of modifying factors at the time when the qualified person converts a measured mineral resource to a probable mineral reserve. A qualified person must classify a measured mineral resource as a probable mineral reserve when his or her confidence in the results obtained from the application of the modifying factors to the measured mineral resource is lower than what is sufficient for a proven mineral reserve. |
proven mineral reserve | A proven mineral reserve is the economically mineable part of a measured mineral resource. For a proven mineral reserve, the qualified person has a high degree of confidence in the results obtained from the application of the modifying factors and in the estimates of tonnage and grade or quality. A proven mineral reserve can only result from conversion of a measured mineral resource. |
qualified person | A qualified person is an individual who is a mineral industry professional with at least five years of relevant experience in the type of mineralization and type of deposit under consideration and in the specific type of activity that person is undertaking on behalf of the registrant; and an eligible member or licensee in good standing of a recognized professional organization at the time the technical report is prepared. For an organization to be a recognized professional organization, it must: (A) Be either: (1) An organization recognized within the mining industry as a reputable professional association, or (2) A board authorized by U.S. federal, state or foreign statute to regulate professionals in the mining, geoscience or related field; (B) Admit eligible members primarily on the basis of their academic qualifications and experience; (C) Establish and require compliance with professional standards of competence and ethics; (D) Require or encourage continuing professional development; (E) Have and apply disciplinary powers, including the power to suspend or expel a member regardless of where the member practices or resides; and; (F) Provide a public list of members in good standing. |
raise | A vertical or inclined underground working that has been excavated from the bottom upward |
reclamation | The restoration of a site after mining or exploration activity is completed. |
refining | A high temperature process in which impure metal is reacted with flux to reduce the impurities. The metal is collected in a molten layer and the impurities in a slag layer. Refining results in the production of a marketable material. |
| | | | | | | | |
Date: February, 2022 | | Page 24-9 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
| | | | | |
Term | Definition |
resistivity | Observation of electric fields caused by current introduced into the ground as a means of studying earth resistivity in geophysical exploration. Resistivity is the property of a material that resists the flow of electrical current |
rock quality designation (RQD) | A measure of the competency of a rock, determined by the number of fractures in a given length of drill core. For example, a friable ore will have many fractures and a low RQD. |
royalty | An amount of money paid at regular intervals by the lessee or operator of an exploration or mining property to the owner of the ground. Generally based on a specific amount per tonne or a percentage of the total production or profits. Also, the fee paid for the right to use a patented process. |
run-in-mine (RIM) | Generally refers to the rehandle of material on surface close to the underground portal, where material is brought to surface and dumped by the underground trucks into stockpiles or into a metal removal plant before being loaded onto surface trucks and hauled for direct feed into the processing plant or hauled to a fun-of-mine stockpile. Run-in-mine refers to this being a mining rehandle before the run-of-mine, and is usually considered specific to one mine. |
run-of-mine (ROM) | Rehandle where the raw mine ore material is fed into the processing plant’s system, usually the crusher. This is where material that is not direct feed from the mine is stockpiled for later feeding. Run-of-mine relates to the rehandle being for any mine material, regardless of source, before entry into the processing plant’s system. |
semi-autogenous grinding (SAG) | A method of grinding rock into fine powder whereby the grinding media consists of larger chunks of rocks and steel balls. |
shaft | A vertical or inclined excavation for the purpose of opening and servicing a mine. It is usually equipped with a hoist at the top, which lowers and raises a conveyance for handling men and material |
shrinkage stoping | In this method, mining is carried out from the bottom of an inclined or vertical ore body upwards, as in open stoping. However, most of the broken ore is allowed to remain in the stope in order both to support the stope walls and to provide a working platform for the overhead mining operations. Ore is withdrawn from chutes in the bottom of the stope in order to maintain the correct amount of open space for working. When mining is completed in a particular stope, the remaining ore is withdrawn, and the walls are allowed to collapse. |
specific gravity | The weight of a substance compared with the weight of an equal volume of pure water at 4°C. |
Squid TEM | Geophysical method. High temperature superconducting quantum interference device (SQUID) magnetometers have been developed in a collaborative project between BHP and CSIRO specifically for application in airborne time domain electromagnetic (TEM) surveying to improve the performance of the system in detection of conductors with longer decay time constants, particularly in the presence of a conductive overburden |
stope | An excavation in a mine, other than development workings, made for the purpose of extracting ore. |
tailings | Material rejected from a mill after the recoverable valuable minerals have been extracted. |
triaxial compressive strength | A test for the compressive strength in all directions of a rock or soil sample |
uniaxial compressive strength | A measure of the strength of a rock, which can be determined through laboratory testing, and used both for predicting ground stability underground, and the relative difficulty of crushing. |
wacke | A sandstone that consists of a mixed variety of angular and unsorted (or poorly sorted) mineral and rock fragments within an abundant matrix of clay and fine silt. |
| | | | | | | | |
Date: February, 2022 | | Page 24-10 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
25.0 RELIANCE ON INFORMATION PROVIDED BY THE REGISTRANT
25.1 Introduction
The QP fully relied on the registrant for the information used in the areas noted in the following sub-sections. The QP considers it reasonable to rely on the registrant for the information identified in those sub-sections, for the following reasons:
•The registrant has been owner and operator of the mining operations for over 15 years;
•The registrant has employed industry professionals with expertise in the areas listed in the following sub-sections;
•The registrant has a formal system of oversight and governance over these activities, including a layered responsibility for review and approval;
•The registrant has considerable experience in each of these areas.
25.2 Macroeconomic Trends
•Information relating to inflation, interest rates, discount rates, exchange rates, and taxes was obtained from the registrant.
This information is used in the economic analysis in Chapter 19. It supports the assessment of reasonable prospects for economic extraction of the mineral resource estimates in Chapter 11, and inputs to the determination of economic viability of the mineral reserve estimates in Chapter 12.
25.3 Markets
•Information relating to market studies/markets for product, market entry strategies, marketing and sales contracts, product valuation, product specifications, refining and treatment charges, transportation costs, agency relationships, material contracts (e.g., mining, concentrating, smelting, refining, transportation, handling, hedging arrangements, and forward sales contracts), and contract status (in place, renewals), was obtained from the registrant.
This information is used in the economic analysis in Chapter 19. It supports the assessment of reasonable prospects for economic extraction of the mineral resource estimates in Chapter 11, and inputs to the determination of economic viability of the mineral reserve estimates in Chapter 12.
25.4 Legal Matters
•Information relating to the corporate ownership interest, the mineral tenure (concessions, payments to retain property rights, obligations to meet expenditure/reporting of work conducted), surface rights, water rights (water take allowances), royalties, encumbrances,
| | | | | | | | |
Date: February, 2022 | | Page 25-1 |
| | | | | |
Ahafo Operations Ghana Technical Report Summary | |
| |
easements and rights-of-way, violations and fines, permitting requirements, and the ability to maintain and renew permits was obtained from the registrant.
This information is used in support of the property description and ownership information in Chapter 3, the permitting and mine closure descriptions in Chapter 17, and the economic analysis in Chapter 19. It supports the reasonable prospects of economic extraction for the mineral resource estimates in Chapter 11, and the assumptions used in demonstrating economic viability of the mineral reserve estimates in Chapter 12.
25.5 Environmental Matters
•Information relating to baseline and supporting studies for environmental permitting, environmental permitting and monitoring requirements, ability to maintain and renew permits, emissions controls, closure planning, closure and reclamation bonding and bonding requirements, sustainability accommodations, and monitoring for and compliance with requirements relating to protected areas and protected species was obtained from the registrant.
This information is used when discussing property ownership information in Chapter 3, the permitting and closure discussions in Chapter 17, and the economic analysis in Chapter 19. It supports the reasonable prospects of economic extraction for the mineral resource estimates in Chapter 11, and the assumptions used in demonstrating economic viability of the mineral reserve estimates in Chapter 12.
25.6 Stakeholder Accommodations
•Information relating to social and stakeholder baseline and supporting studies, hiring and training policies for workforce from local communities, partnerships with stakeholders (including national, regional, and state mining associations; trade organizations; fishing organizations; state and local chambers of commerce; economic development organizations; non-government organizations; and, state and federal governments), and the community relations plan was obtained from the registrant.
This information is used in the social and community discussions in Chapter 17, and the economic analysis in Chapter 19. It supports the reasonable prospects of economic extraction for the mineral resource estimates in Chapter 11, and the assumptions used in demonstrating economic viability of the mineral reserve estimates in Chapter 12.
25.7 Governmental Factors
•Information relating to taxation and royalty considerations at the Project level, monitoring requirements and monitoring frequency, bonding requirements, violations and fines and was obtained from the registrant.
This information is used in the discussion on royalties and property encumbrances in Chapter 3, the monitoring, permitting and closure discussions in Chapter 17, and the economic analysis in Chapter 19. It supports the reasonable prospects of economic extraction for the mineral resource estimates in Chapter 11, and the assumptions used in demonstrating economic viability of the mineral reserve estimates in Chapter 12.
| | | | | | | | |
Date: February, 2022 | | Page 25-2 |
Nevada Operations
Nevada, USA
Technical Report Summary
Report current as of:
December 31, 2021
Qualified Person:
Mr. Donald Doe, RM SME.
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
NOTE REGARDING FORWARD-LOOKING INFORMATION
This Technical Report Summary contains forward-looking statements within the meaning of the U.S. Securities Act of 1933 and the U.S. Securities Exchange Act of 1934 (and the equivalent under Canadian securities laws), that are intended to be covered by the safe harbor created by such sections. Such forward-looking statements include, without limitation, statements regarding Newmont’s expectation for its mines and any related development or expansions, including estimated cashflows, production, revenue, EBITDA, costs, taxes, capital, rates of return, mine plans, material mined and processed, recoveries and grade, future mineralization, future adjustments and sensitivities and other statements that are not historical facts.
Forward-looking statements address activities, events, or developments that Newmont expects or anticipates will or may occur in the future and are based on current expectations and assumptions. Additionally, forward-looking statements regarding Nevada Gold Mines are based largely upon information provided by the Operating Manager, Barrick, to Newmont. Although Newmont’s management believes that its expectations are based on reasonable assumptions, it can give no assurance that these expectations will prove correct. Such assumptions, include, but are not limited to: (i) there being no significant change to current geotechnical, metallurgical, hydrological and other physical conditions; (ii) permitting, development, operations and expansion of operations and projects being consistent with current expectations and mine plans, including, without limitation, receipt of export approvals; (iii) political developments in any jurisdiction in which Newmont operates being consistent with its current expectations; (iv) certain exchange rate assumptions being approximately consistent with current levels; (v) certain price assumptions for gold, copper, silver, zinc, lead and oil; (vi) prices for key supplies being approximately consistent with current levels; and (vii) other planning assumptions.
Important factors that could cause actual results to differ materially from those in the forward-looking statements include, among others, risks that estimates of mineral reserves and mineral resources are uncertain and the volume and grade of ore actually recovered may vary from our estimates, risks relating to fluctuations in metal prices; risks due to the inherently hazardous nature of mining-related activities; risks related to the jurisdictions in which we operate, uncertainties due to health and safety considerations, including COVID-19, uncertainties related to environmental considerations, including, without limitation, climate change, uncertainties relating to obtaining approvals and permits, including renewals, from governmental regulatory authorities; and uncertainties related to changes in law; as well as those factors discussed in Newmont’s filings with the U.S. Securities and Exchange Commission, including Newmont’s latest Annual Report on Form 10-K for the period ended December 31, 2021, which is available on newmont.com.
Newmont does not undertake any obligation to release publicly revisions to any “forward-looking statement,” including, without limitation, outlook, to reflect events or circumstances after the date of this document, or to reflect the occurrence of unanticipated events, except as may be required under applicable securities laws. Investors should not assume that any lack of update to a previously issued “forward-looking statement” constitutes a reaffirmation of that statement. Continued reliance on “forward-looking statements” is at investors’ own risk.
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
CONTENTS
| | | | | |
Date: February 2022 | Page i |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
| | | | | |
Date: February 2022 | Page ii |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
| | | | | |
Date: February 2022 | Page iii |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
| | | | | |
Date: February 2022 | Page iv |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
| | | | | |
Date: February 2022 | Page v |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
| | | | | |
Date: February 2022 | Page vi |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
| | | | | |
Date: February 2022 | Page vii |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
TABLES
| | | | | |
Date: February 2022 | Page viii |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
FIGURES
| | | | | |
Date: February 2022 | Page ix |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
| | | | | |
Date: February 2022 | Page x |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
| | | | | |
Date: February 2022 | Page xi |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
1.0 EXECUTIVE SUMMARY
1.1 Introduction
This technical report summary (the Report) was prepared for Newmont Corporation (Newmont) on the Nevada Operations (Nevada Operations or the Project) that are located in Nevada.
The Project is operated as a joint venture (JV) through Nevada Gold Mines, LLC (NGM). Barrick Gold Corporation (Barrick) is the JV operator and owns 61.5%, with Newmont owning the remaining 38.5% JV interest.
1.2 Terms of Reference
The Report was prepared to be attached as an exhibit to support mineral property disclosure, including mineral resource and mineral reserve estimates, for the Nevada Operations in Newmont’s Form 10-K for the year ending December 31, 2021.
The Nevada Operations consist of 10 underground and 12 open pit active mining operations, two autoclave facilities, two roasting facilities, two oxide mills, two flotation plants and nine heap leach facilities, forming five major mining/processing complexes centered at Carlin, Cortez, Long Canyon, Phoenix and Turquoise Ridge.
Active open pit mining operations include Crossroads, Gold Quarry, Goldstrike, Goldstar, Long Canyon, Phoenix, Pipeline, and Vista. Two deposits, the Mega Pit at Turquoise Ridge and the South Arturo deposit at Carlin that are planned to be mined using open pit methods, are not currently active, but are planned to be mined in 2022–2023. Active underground mining operations include Cortez Hills underground, Exodus, Goldstrike, El Niño, Leeville, Pete Bajo, Turquoise Ridge Underground, and Vista. Underground exploration development is underway at the Goldrush deposit.
Unless otherwise indicated, all financial values are reported in United States (US) currency (US$). Units may be in either metric or US customary units as identified in the text. Mineral resources and mineral reserves are reported using the definitions in Subpart 229.1300 – Disclosure by Registrants Engaged in Mining Operations in Regulation S–K 1300 (SK1300). The Report uses US English. The Report contains forward-looking information; refer to the note regarding forward-looking information at the front of the Report.
1.3 Property Setting
The Nevada Operations are centered on northern Nevada, and are bisected by Interstate 80 (I-80), which provides access to most of the Project area.
Access for the Carlin Complex is generally from Elko, 26 miles west on I-80 to Carlin which is the closest town to the mine sites. In addition, various alternate access routes use Nevada State Route 766, and Elko and Eureka County roads. These roads are well maintained, and most are paved.
The Cortez Complex is reached by travelling approximately 32 miles east from the town of Battle Mountain on the I-80. Alternative access is from Elko, Nevada, approximately 45 miles
| | | | | | | | |
Date: February 2022 | | Page 1-1 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
west to the Beowawe exit, then approximately 35 miles south on Nevada State Route 306, which extends southward from I-80.
The Long Canyon Complex is accessed from either the I-80 east-bound route through Wells or I-80 west-bound through Wendover, with the main entrance just off the Oasis/Montello interchange. The mine area is within one mile of the freeway with the pit area about four miles west.
The Phoenix Complex is accessed from I-80 at Battle Mountain, traveling approximately 12 miles south on the paved Nevada State Route 305, and then west a short distance on a paved/gravel county access road.
The Turquoise Ridge Complex is accessed from a turnoff at the settlement of Golconda, 25 miles east of Winnemucca, then following a paved road for a further 25 miles, and thereafter by an improved gravel road to the mine gates. It is then 10 miles to the west mine gate and 25 miles to the east mine gate.
The Nevada operations are crossed by a network of gravel roads, providing easy access to various portions of the sites. The majority of the roads are suitable for all-weather conditions; however, in extreme winter conditions, roads may be closed for snow removal.
The Union Pacific Rail line runs parallel to I-80. NGM operates the Dunphy Rail Terminal, which is located 27 miles west of Carlin, for the transportation of bulk commodities such as lubricants, fuel, and ball mill consumables. These bulk commodities are road-transported from the Dunphy Rail Terminal to each site using commercial trucking services. Elko is serviced by commercial flights to Salt Lake City, Utah.
The Nevada Operations are located in a high desert region. Operations are conducted year-round.
The Project is located in a major mining region and local resources including labor, water, power, natural gas, and local infrastructure for transportation of supplies are well established. Mining has been an active industry in northern Nevada for more than 150 years. Elko (pop. 20,300) is a local hub for mining operations in northern Nevada and services necessary for mining operations are readily available.
1.4 Ownership
NGM is a JV between Barrick and Newmont. Barrick is the JV operator and has a 61.5% interest, with Newmont owning the remaining 38.5% interest. The JV area of interest (AOI) covers a significant portion of northern Nevada.
1.5 Mineral Tenure, Surface Rights, Water Rights, Royalties and Agreements
The Nevada Operations currently includes 15 plans of operations (PoOs) and eight exploration PoOs. The area includes private land (surface and minerals) owned or controlled by NGM, and land owned by the federal government that is administered by the Bureau of Land Management (BLM).
| | | | | | | | |
Date: February 2022 | | Page 1-2 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Within the operations PoO areas are 9,205 lode, millsite, placer and patented claims covering an area of approximately 163,214 acres. Within the exploration PoO areas, 2,180 lode, millsite, placer and patented claims cover an area of approximately 43,363 acres. Between the operations and the exploration PoOs, NGM holds a total of 11,385 claims covering an area of approximately 206,578 acres.
In addition, NGM holds a number of fee properties, within the operations and exploration PoOs. Collectively, these cover an area of approximately 78,621 acres.
On 11 March, 2019, Barrick and Newmont announced the formation of the NGM JV. Newmont, Barrick, and their respective affiliates that held properties in the AOI contributed to NGM the respective rights, titles and interests in, to, or under, all properties located in the AOI and any other assets, properties or rights located in Nevada. Newmont and Barrick excluded certain development and exploration properties that the companies held within the AOI from the JV; these included Newmont’s Fiberline and Mike projects, and Barrick’s Fourmile project. The JV has a mechanism for the potential contribution of the excluded properties to NGM in the future.
A number of agreements exist with federal, state, and third-party entities and these are monitored using a land management database.
NGM holds all necessary surface rights for the current mining operations. Additional surface rights will be required, for future mining projects. The Goldrush PoO is currently moving through the National Environmental Policy Act (NEPA) process (see discussion in Chapter 1.17.3).
NGM currently maintains a combination of approximately 1,250 active surface and groundwater rights within 38 hydrographic basins. NGM holds all necessary water rights for the LOM plan envisaged in this Report.
There are numerous royalties that pertain to the active mines within the Nevada Operations. Royalty payments vary, as the payments depend upon actual tonnages mined, the amount of gold recovered from that mined material, the deposit being mined, the receiving entity, and the type of royalty. A number of the claims have inactive royalties attached, which are not currently triggered as the claims are not being mined. In connection with the formation of Nevada Gold Mines, each of Barrick and Newmont was granted a 1.5% net smelter returns royalty over the respective properties they contributed to the NGM JV. Each of these “retained royalties” is only payable once the aggregate production from the properties subject to the royalty exceeds the publicly reported mineral reserves and mineral resources as of December 31, 2018. The state of Nevada imposes a 5% Net Proceeds of Minerals Tax on the value of all minerals severed in the State. This tax is calculated and paid based on a prescribed net income formula. Separately, a Nevada Mining Education Tax based on gross revenue, was introduced during 2021.
1.6 Geology and Mineralization
The deposits that comprise the Nevada Operations are considered to be examples of Carlin-style carbonate-hosted disseminated gold–silver deposits and intrusion-related gold–copper–silver skarn deposits.
The geology of northern Nevada displays a complicated sequence of orogeny and tectonism. Within the Project area, the mineralization is reported based on five mining complexes, Carlin, Cortez, Long Canyon, Phoenix and Turquoise Ridge.
| | | | | | | | |
Date: February 2022 | | Page 1-3 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Mineralization is hosted in lower Paleozoic sedimentary rocks or associated with Late Jurassic–Eocene intrusions. The majority of the deposits have some structural control, with mineralization commonly associated with the Roberts Mountains thrust. Pervasiveness and intensity of alteration varies both within and between gold deposits, depending on magnitude of the mineralizing system, nature of the host rock, and structural preparation.
Carlin Trend-style mineralization consists primarily of micrometer-sized gold and sulfides disseminated in zones of siliciclastic and decarbonated calcareous rocks and commonly associated with jasperoids. Mineralization is predominantly in the form of oxides, sulfides, or sulfide minerals in carbonaceous rocks, and the ore type determines how and where it is processed. Copper oxide mineralization locally contains minor amounts chalcanthite, malachite, chrysocolla, azurite, and lesser cuprite. In hypogene mineralization, chalcopyrite occurs as disseminations and bedded replacements with skarn and silicate minerals, and in conjunction with pyrite.
1.7 History and Exploration
Early-stage exploration included geological mapping, geochemical samples (stream sediment, soil, and rock chip samples), geophysical surveys (airborne and ground magnetics; radiometrics and electromagnetics; gravity, resistivity, and controlled-source audio-frequency telluromagnetics and magnetotellurics (MT); self-potential; induced-polarization (IP); time domain pole-dipole IP; time domain MT/IP using a distributed assay system; electrical logging of drill holes; and downhole IP. The majority of the surface-based grass roots exploration tools are superseded by mining and drill data.
Exploration potential exists adjacent to many of the deposits, along strike and at depth along favorable mineralized structures and within the favorable host lithologies.
1.8 Drilling and Sampling
Across the entire AOI, drilling totals over 203,000 drill holes for >82 Mft of drilling. Over the Project history, drilling included reverse circulation (RC), core, air rotary, mud rotary, and Cubex methods.
Logging conducted depended on the operator of the complex at the time the information was collected, and the drill type. Typically, logging collected information such as lithology, stratigraphy, basic structural data, recovery, alteration, and mineralization. For mining operations, logging could also record metallurgical type, intensity codes for metallurgy and alteration, and geotechnical parameters.
Collar surveys have used optical surveys, field estimates, Brunton compass and pacing, compass-and-string distance measurements, and for underground operations, measurements from surveyed control points, face, ribs and sill to triangulate each collar location. Down-hole surveys included downhole single-shot or multi-shot film camera (typical for most underground surveys), use of a downhole precession gyroscopic survey tool, a gyroscopic tool requiring initial orientation with a compass, and north-seeking or conventional gyroscopic tools.
Sampling is variable by mining complex and mineralization style. Air-rotary and mud-rotary drill holes were sampled on 5–100 ft intervals. Cubex drilling was sampled on 5–10 ft intervals. RC
| | | | | | | | |
Date: February 2022 | | Page 1-4 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
drill holes were typically sampled on 5 ft intervals. Core samples were nominally taken at 5 ft intervals, but could vary to a minimum of 1 ft to respect lithological contacts.
The majority of the density data were from measurements collected by exploration or mine site personnel using the water displacement method.
Given the long history of the Nevada Operations, there are numerous laboratories that were used over the Project history. Laboratories were both independent and non-independent. In the earlier stages of Project testwork, the idea of laboratory accreditation had not been developed. In later assay campaigns, accreditations were not typically recorded in the database. Currently, all independent laboratories used for chemical analysis are accredited for selected analytical techniques.
Sample preparation has varied over the 60 years of modern Project history, in line with advancing scientific knowledge, changes in equipment, and operational experience. Currently, sample preparation procedures include drying, crushing and pulverizing. As with sample preparation, analytical methods have changed over the Project history. Currently, sample analytical procedures include:
•ALS Chemex: fire assays (FA) and atomic absorption (AA) finish for gold; samples reporting >0.1 oz/st Au on the initial assay re-assayed by FA with gravimetric finish; cyanide leach gold assays for initial FAs >0.008 oz/st Au; cyanide leach and preg rob capacity; LECO testing; multi-element analyses by aqua regia digestion/inductively coupled plasma-atomic emission spectroscopy (ICP-AES)/ICP-mass spectroscopy (ICP-MS), 51 elements or 48 element analyses by four acid and ICP-AES/ICP-MS; other analyses may be requested, and include arsenic, total carbon, total sulfur, sulfide sulfur, carbonate carbon, and organic carbon;
•AAL: 1 assay ton fire assays with an AA finish for gold;
•Mine laboratories: 1 assay ton fire assays with an AA finish for gold; samples with gold grade >0.438 oz/st are completed by a ½ assay ton fire assay with a gravimetric finish. If the sample gold grade is above the open pit cut-off grade, the samples are analyzed for cyanide leach, % preg rob, total carbon, total sulfur, sulfide sulfur, carbonate, and organic carbon for ore characterization purposes. On request, underground muck samples can be equal weight composited for further ore characterization analyses including total carbon, total sulfur, sulfide sulfur, carbonate carbon, organic carbon, and arsenic.
Prior to the mid-1990s, few companies had rigorous quality assurance and quality control (QA/QC) programs in place. QA/QC had typically consisted, where undertaken, of reanalysis of drill core or other samples when later sampling indicated a potential problem. In the case of the NGM Operations, QA/QC samples were submitted for RC and core samples from about 1990. Typical QA/QC measures include submission of blank materials, certified or standard reference materials (standards), and field duplicate samples. Check assays may not be routinely performed. Typical checks were undertaken on pulps and coarse reject samples to test the analytical processes and preparation procedure, respectively.
Project geologists review the assay results and periodically request a batch re-run and/or entire hole based on expected versus actual results. Analyses that appear to be outside best practice guidelines for exploration of two standard deviations will result in a request of the laboratory that completed the original analysis to undertake a re-run of the sample batch that the failed control was in. Check assay programs are the responsibility of the individual geologists.
| | | | | | | | |
Date: February 2022 | | Page 1-5 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Several systems and programs are used to control and ensure assay data quality. These include standards for technician training, periodic process checks, equipment preventive maintenance, centralized reagent/standard preparation, control samples (reference materials) and blanks assayed with the samples, data verification, periodic check assays, and participation in industry round-robin programs.
1.9 Data Verification
Validation checks are performed by NGM operations personnel on data used to support estimation comprise checks on surveys, collar coordinates, lithology data (cross-checking from photographs), and assay data. Errors noted are rectified in the database prior to data being flagged as approved for use in resource estimation.
A number of third-party consultants have performed external data reviews. These external reviews were undertaken in support of acquisitions, support of feasibility-level studies, and in support of technical reports, producing independent assessments of the database quality. No significant problems with the database, sampling protocols, flowsheets, check analysis program, or data storage were noted.
The QP visited the Nevada Operations on many occasions, most recently to the Carlin Complex in 2019, and visited the Goldrush project during 2021. He inspected the underground workings at Leeville and Pete Bajo, viewed the open pit operations, and toured the Gold Quarry roaster. During the Goldrush visit he inspected the underground workings, reviewed core, and met with project representatives. The QP also toured the planned locations for some of the surface infrastructure. The QP’s personal inspection supports the use of the data in mineral resource and mineral reserve estimation, and in mine planning.
1.10 Metallurgical Testwork
During the 60+ year history of Nevada Operations mine development, a significant number of metallurgical studies and accompanying laboratory-scale and/or pilot plant tests have been completed. Either internal metallurgical research facilities or external consultants undertake the research. Recent external testwork was performed at McClelland Laboratories, Hazen Research, Macpherson Laboratories, McGill University, Svedala, and Outukumpu. Internal testwork facilities included the Goldstrike Metallurgical Laboratory, Gold Quarry Metallurgical Laboratory, Newmont Metallurgical Services in Englewood, Colorado and the AuTec Metallurgical Laboratory located in Vancouver, British Columbia, Canada.
Metallurgical testwork included: mineralogy; head grades and screen analyses; bottle roll, bench and column cyanide leaching; carbon adsorption/activation tests; direct cyanide leach testwork; carbon-in-leach tests; agglomeration tests; cyanide amenability tests; bench or circulating fluidized bed roasting tests; calcine tests; magnetic separation testwork; bench-top roaster followed by CIL testwork; bench-top alkaline pressure leach tests followed by CIL tests; calcium thiosulfate and resin leach tests; bench-top alkaline pressure leach tests followed by thiosulfate resin in leach testwork; sulfidization acidification re-neutralization and thickening or SART testwork; reagent consumption reviews; impurity reviews; standard autoclaving and leach tests; grindability (comminution) tests (SMC, breakage parameter, Bond work index, drop weight index, rod work index, unconfined compressive strength, semi-autogenous grind (SAG) power index); thickener testwork; batch and pilot plant tests
| | | | | | | | |
Date: February 2022 | | Page 1-6 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
These test programs were sufficient to establish the optimal processing routes for the non-refractory and refractory ores, and the weathering state of the ores (oxide, leached, enriched, transition, sulfide), and was performed on mineralization that was typical of the deposits. The results obtained supported estimation of recovery factors for the various ore types depending on the process method selected.
Numerous processing methods are used within the Nevada Operations, including CIL for higher-grade oxide ore, heap leaching for lower-grade oxide ore, roasting for carbonaceous refractory ore, and pressure oxidation (POX) for higher-grade sulfidic ore.
Future ore testing is completed according to the needs of the optimized blend planning for the combined NGM operations. Current ore testing is completed monthly by performing testwork on feed stockpile samples.
Gold recovery is a function of the processing method (e.g., heap leaching, CIL, roasting, and arsenic concentration for refractory ore) and the lithology of the mineralization being processed. As applicable, recovery estimates include consideration of the head grade, cyanide-soluble gold to fire assay gold ratio, sulfide sulfur concentration, total organic carbon concentration, and silica concentration.
Copper recovery models were derived from a statistical review of the metallurgical data and range in complexity from simple, fixed recoveries to complex, multi-variable equations. The following input variables were available as possible drivers of recovery: head grade, copper leach ore type, alteration type, formation, and various trace elements.
Recovery ranges projected for the LOM operations include:
•Gold:
◦Oxide leach: 57–75%;
◦Oxide mill: 73–88%;
◦Goldstrike roaster: 84–92%;
◦Goldstrike autoclave: 50–96%;
◦Gold Quarry roaster: 84–92%;
◦Sage (Turquoise Ridge) autoclave: average 84%;
◦Phoenix mill: average 70%;
•Copper:
◦Phoenix mill: average 71%;
◦Copper leach: average 49%;
•Silver:
◦Phoenix mill: average 38%.
Samples selected for metallurgical testing during feasibility and development studies were representative of the various styles of mineralization within the different deposits. Samples were selected from a range of locations within the deposits. Sufficient samples were taken, and tests were performed using sufficient sample mass for the respective tests undertaken. Variability assessments are supported by production and extensive open pit and underground exposures.
| | | | | | | | |
Date: February 2022 | | Page 1-7 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Depending upon the specific processing facility, several processing factors or deleterious elements could have an economic impact on extraction efficiency of a certain ore source, based either on the presence, absence, or concentration of the following constituents in the processing stream:
•Organic carbon;
•Sulfide sulfur;
•Carbonate carbon;
•Arsenic
•Mercury;
•Antimony;
•Copper.
However, under normal ore routing and blending practices at NGM where material from several sites may be processed at one facility, the above list of constituents is typically not a concern.
1.11 Mineral Resource Estimation
1.11.1 Estimation Methodology
Estimation was typically performed by Nevada Operations personnel. All mineralogical, drilling, and background data and information were provided to the estimators by the geological staff at the operations or by exploration staff.
Exploratory data analysis was undertaken on sample and composite data, as required, to understand the statistical features within and between geologic and mineralization domains. High-grade anomalous values were controlled through the use of top-cutting and/or high-grade estimation restrictions, applied by deposit and domain. Composite lengths varied by complex and planned mining method, ranging from 2.5–20 ft. Variographic analyses were completed by domain.
Estimation and interpolation methods varied by deposit. The following methods were used: ordinary kriging, indicator kriging (IK), local indicator kriging (LIK), inverse distance weighting to the second power (ID2), inverse distance weighting to the third power (ID3), and inverse distance weighting to the fifth power (ID5). Typically, alternate grade interpolations (including nearest neighbor) were performed for use in model validation and sensitivity testing. Depending on the deposit, interpolation was performed in multiple (up to eight) passes. Search neighborhoods were based on variography, mineralization geometry, or on selected drill spacings. Minimum and maximum numbers of informing samples varied by deposit, as did the number of samples allowed to be used from a single drill hole. Dynamic anisotropy could be used to allow for a localized change in the strike, dip, and plunge orientation of the mineralization. Block models were flagged for mining depletion.
Mineralization solids were checked for conformity to drill hole data, continuity, similarity between sections, overlaps, appropriate terminations between holes and into undrilled areas. Validation procedures were undertaken on the estimations. These could include comparison of global mean grades, visual comparisons to composite grades, comparisons to reconciliation (when
| | | | | | | | |
Date: February 2022 | | Page 1-8 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
available), change of support corrections estimated using a discrete Gaussian model under a diffusion model assumption, grade-tonnage curves, slope of regression calculations, comparison to NN analysis and swath plots.
Blocks were classified in the model, based on relative confidence in the estimated grades, into measured, indicated, and inferred. Criteria for classification were defined within each deposit, and based on various combinations of: proximity to nearby drilling data (distances to nearest 1, 2, or 3 drill holes); geostatistical drill spacing studies; qualitative assessment of confidence in the underlying geologic interpretations; historical classification assignments; and classification smoothing algorithms.
Mineralization considered potentially amenable to open pit mining methods was constrained within a conceptual pit shell using the Lerchs–Grossmann (LG) algorithm within Vulcan software. Mineralization considered potentially amenable to underground methods was constrained within mineable shapes generated using Mineable Stope Optimizer (MSO) software.
Commodity prices used in resource estimation are based on long-term analyst and bank forecasts. An explanation of the derivation of the commodity prices is provided in Chapter 16.2. The estimated timeframe used for the price forecasts is the 24-year LOM that supports the mineral reserve estimates.
The resources are reported at varying cut-off values, which are based on the material type being mined, the mining method and the designated process facility. As a result, cut-off values can vary significantly by material type.
1.11.2 Mineral Resource Statement
Mineral resources are reported using the mineral resource definitions set out in SK1300. The reference point for the estimate is in situ. Mineral resources are reported exclusive of those mineral resources converted to mineral reserves.
Mineral resources are reported on a 100% basis. Barrick owns a 61.5% JV interest, with Newmont owning the remaining 38.5% JV interest.
The mineral resource estimates for the Nevada Operations are provided as follows:
•Gold: Table 1-1 (measured and indicated) and Table 1-2 (inferred);
•Silver: Table 1-3 (measured and indicated) and Table 1-4 (inferred);
•Copper: Table 1-5 (measured and indicated) and Table 1-6 (inferred).
Tonnages in the tables are metric tonnes.
1.11.3 Factors That May Affect the Mineral Resource Estimate
Factors that may affect the mineral resource estimate include: changes to long-term metal price assumptions; changes in local interpretations of mineralization geometry and continuity of mineralized zones; changes to geological and grade shape and geological and grade continuity assumptions; changes to input parameters used in the pit shells and stope outlines constraining the mineral resources; changes to the cut-off grades used to constrain the estimates; variations
| | | | | | | | |
Date: February 2022 | | Page 1-9 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
in geotechnical, mining, and processing recovery assumptions; and changes to environmental, permitting and social license assumptions.
| | | | | | | | |
Date: February 2022 | | Page 1-10 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 1-1: Measured and Indicated Mineral Resource Statement (Gold)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Complex | Measured Mineral Resources | Indicated Mineral Resources | Measured and Indicated Mineral Resources |
Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) |
Carlin | 45,400 | 3.56 | 5,210 | 140,100 | 1.73 | 7,780 | 185,500 | 2.18 | 12,980 |
Cortez | 700 | 7.02 | 170 | 99,500 | 1.20 | 3,850 | 100,300 | 1.25 | 4,010 |
Long Canyon | 500 | 3.47 | 60 | 9,800 | 4.05 | 1,280 | 10,400 | 4.02 | 1,340 |
Turquoise Ridge | 15,300 | 3.10 | 1,530 | 33,700 | 3.57 | 3,870 | 49,100 | 3.42 | 5,400 |
Phoenix | 7,600 | 0.53 | 130 | 218,200 | 0.45 | 3,140 | 225,800 | 0.45 | 3,270 |
Total | 69,600 | 3.17 | 7,090 | 501,300 | 1.24 | 19,910 | 571,000 | 1.47 | 27,000 |
Table 1-2: Inferred Mineral Resource Statement (Gold)
| | | | | | | | | | | |
Complex | Inferred Mineral Resources |
Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) |
Carlin | 110,700 | 2.1 | 7,510 |
Cortez | 124,400 | 1.6 | 6,380 |
Long Canyon | 2,600 | 3.6 | 300 |
Turquoise Ridge | 18,200 | 2.0 | 1,200 |
Phoenix | 49,200 | 0.4 | 580 |
Total | 305,000 | 1.6 | 15,970 |
Table 1-3: Measured and Indicated Mineral Resource Statement (Silver)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Complex | Measured Mineral Resources | Indicated Mineral Resources | Measured and Indicated Mineral Resources |
Tonnage (x 1,000 t) | Grade (g/t Ag) | Cont. Silver (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Ag) | Cont. Silver (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Ag) | Cont. Silver (x 1,000 oz) |
Phoenix | 7,600 | 5.57 | 1,360 | 218,200 | 5.54 | 38,860 | 225,800 | 5.54 | 40,220 |
Total | 7,600 | 5.57 | 1,360 | 218,200 | 5.54 | 38,860 | 225,800 | 5.54 | 40,220 |
| | | | | | | | |
Date: February 2022 | | Page 1-11 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 1-4: Inferred Mineral Resource Statement (Silver)
| | | | | | | | | | | |
Complex | Inferred Mineral Resources |
Tonnage (x 1,000 t) | Grade (g/t Ag) | Cont. Silver (x 1,000 oz) |
Phoenix | 49,200 | 5.6 | 8,840 |
Total | 49,200 | 5.6 | 8,840 |
Table 1-5: Measured and Indicated Mineral Resource Statement (Copper)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Measured Mineral Resources | Indicated Mineral Resources | Measured and Indicated Mineral Resources |
Tonnage (x 1,000 t) | Grade (Cu %) | Cont. Copper (M lbs) | Tonnage (x 1,000 t) | Grade (Cu %) | Cont. Copper (M lbs) | Tonnage (x 1,000 t) | Grade (Cu %) | Cont. Copper (M lbs) |
Phoenix | 8,000 | 0.14 | 20 | 289,600 | 0.14 | 880 | 297,600 | 0.14 | 910 |
Total | 8,000 | 0.14 | 20 | 289,600 | 0.14 | 880 | 297,600 | 0.14 | 910 |
Table 1-6: Inferred Mineral Resource Statement (Copper)
| | | | | | | | | | | |
Area | Inferred Mineral Resources |
Tonnage (x 1,000 t) | Grade (Cu %) | Cont. Copper (M lbs) |
Phoenix | 51,600 | 0.1 | 150 |
Total | 51,600 | 0.1 | 150 |
Notes to Accompany Mineral Resource Tables:
1.Mineral resources are current as at December 31, 2021, using the definitions in SK1300. The Qualified Person responsible for the estimate is Mr. Donald Doe, RM SME, Group Executive, Reserves, a Newmont employee.
2.The reference point for the mineral resources is in situ.
3.Mineral resources are reported on a 100% basis. Barrick owns a 61.5% JV interest, with Newmont owning the remaining 38.5% JV interest.
4.Mineral resources are reported exclusive of mineral reserves. Mineral resources that are not mineral reserves do not have demonstrated economic viability.
5.Mineral Resources that are potentially amenable to open pit mining methods are constrained within a designed pit shell. Mineral Resources that are potentially amenable to underground mining methods are constrained within conceptual stope designs. Parameters used are summarized in Table 11-1 and Table 11-2.
6.Tonnages are metric tonnes rounded to the nearest 100,000. Gold and silver grades are rounded to the nearest 0.01 gold grams per tonne. Copper grade is in %. Gold and silver ounces and copper pounds are estimates of metal contained in tonnages and do not include allowances for processing losses. Contained (cont.) gold and silver ounces are reported as troy ounces, rounded to the nearest 10,000. Copper is reported as pounds and rounded to the nearest 10 million pounds. Rounding of tonnes and contained metal content as required by reporting guidelines may result in apparent differences between tonnes, grade and contained metal content. Due to rounding, some cells may show a zero (“0”). Totals may not sum due to rounding.
| | | | | | | | |
Date: February 2022 | | Page 1-12 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
1.12 Mineral Reserve Estimation
1.12.1 Estimation Methodology
Measured and indicated mineral resources were converted to mineral reserves. Mineral reserves in the Nevada Operations area are estimated for the Carlin, Cortez, Long Canyon, Phoenix and Turquoise Ridge complexes using open pit mining, and the Carlin, Cortez, and Turquoise Ridge complexes using underground mining. Stockpiled material is also included in the mineral reserve estimates. All Inferred blocks are classified as waste in the cashflow analysis that supports mineral reserve estimation.
Mineral Reserves are supported by a mine plan, an engineering analysis, and the application of modifying factors.
For the open pits, optimization work involved floating cones at a series of gold prices. The generated nested pit shells were evaluated using the reserve gold price of US$1,200/oz (and $2.75/lb Cu and $16.50/oz Ag for Phoenix) and a 5% discount rate. The pit shells with the highest net present value (NPV) were selected for detailed engineering design work. A realistic schedule was developed in order to determine the optimal pit shell for each deposit; schedule inputs include the minimum mining width, and vertical rate of advance, mining rate and mining sequence. The block models were constructed to include the expected dilution based on mining methods, bench height and other factors. The current mine and process reconciliation data appear to support this assumption.
Underground mines are designed using zones that are amenable to different mining methods based on geotechnical and access considerations, the deposit shape, orientation and grade, and mining depths.
Cut-off grades were determined based on a combination of the selected metal price, applicable royalty payments, mining costs, process operating costs, and on-site (and off-site) metal recoveries by material type, and selected process method. Operational cut-off grades ranged from:
•Carlin Complex: 0.20–7.06 g/t Au;
•Cortez Complex: 0.17–3.41 g/t Au;
•Long Canyon: 0.24 g/t Au;
•Turquoise Ridge Complex: 0.17–7.99 g/t Au.
Revenue from the Phoenix Complex is generated from three products: gold, silver, and copper. A revenue cut-off, rather than a grade cut-off, is used that integrates the economics (recovery, metal prices, and costs) of all three metals. The revenue calculation only includes incremental mining costs beyond the pit rim. The mineral reserves for the Phoenix Complex are reported using a zero-dollar net revenue cut-off.
The mine plans assume use of a number of different mining methods and variants including: long-hole stoping; long-hole stope retreat; underhand drift-and-fill; and overhand drift-and-fill.
Stopes were created using Mineable Stope Optimizer (MSO) software at the required stope height, length and cut-off criteria based on the mine area. The stope widths depend on the
| | | | | | | | |
Date: February 2022 | | Page 1-13 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
stope cut-off and dilution (over-break) added to stope design, and the mining method used. A set of marginal stopes could also be considered in the reserve process.
Blocks that were modelled as waste or low-grade were included in a designed stope shape as internal dilution. Additional tonnage dilution percentages could be added by site personnel, where required, based on historical reconciliation data for a particular mining method. Cut-off grades are determined based on a combination of the selected metal price, applicable royalty payments, mining costs, process operating costs, and on-site (and off-site) metal recoveries by material type, selected process method, and mining method.
Stockpile estimates were based on mine dispatch data; the grade comes from closely-spaced blasthole sampling and tonnage sourced from truck factors. The stockpile volumes were typically updated based on monthly surveys. The average grade of the stockpiles was adjusted based on the material balance to and from the stockpile.
Commodity prices used in mineral reserve estimation are based on long-term analyst and bank forecasts. An explanation of the derivation of the commodity prices is provided in Chapter 16.2. The estimated timeframe used for the price forecasts is the 24-year LOM that supports the mineral reserve estimates.
1.12.2 Mineral Reserve Statement
Mineral reserves have been classified using the mineral reserve definitions set out in SK1300. The reference point for the mineral reserve estimate is the point of delivery to the process facilities. Mineral reserves are reported on a 100% basis. Barrick owns a 61.5% JV interest, with Newmont owning the remaining 38.5% JV interest.
The mineral resource estimates for the Nevada Operations are provided as follows:
•Gold: Table 1-7;
•Silver Table 1-8;
•Copper: Table 1-9.
Tonnages in the table are metric tonnes.
| | | | | | | | |
Date: February 2022 | | Page 1-14 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 1-7: Proven and Probable Mineral Reserve Statement (Gold)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Proven Mineral Reserves | Probable Mineral Reserves | Proven and Probable Mineral Reserves |
Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) |
Carlin | 38,300 | 6.01 | 7,400 | 129,800 | 2.70 | 11,280 | 168,000 | 3.46 | 18,670 |
Cortez | 3,500 | 4.43 | 500 | 103,000 | 4.16 | 13,780 | 106,500 | 4.17 | 14,290 |
Long Canyon | 300 | 1.43 | 20 | 600 | 1.06 | 20 | 1,000 | 1.18 | 40 |
Turquoise Ridge | 42,900 | 5.09 | 7,030 | 32,600 | 6.59 | 6,920 | 75,600 | 5.74 | 13,940 |
Phoenix | 13,500 | 0.72 | 310 | 155,800 | 0.59 | 2,960 | 169,300 | 0.60 | 3,270 |
Total | 98,500 | 4.82 | 15,260 | 421,800 | 2.58 | 34,960 | 520,300 | 3.00 | 50,220 |
Table 1-8: Proven and Probable Mineral Reserve Statement (Silver)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Proven Mineral Reserves | Probable Mineral Reserves | Proven and Probable Mineral Reserves |
Tonnage (x 1,000 t) | Grade (g/t Ag) | Cont. Silver (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Ag) | Cont. Silver (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Ag) | Cont. Silver (x 1,000 oz) |
Phoenix | 13,500 | 7.40 | 3,200 | 155,800 | 6.35 | 31,810 | 169,300 | 6.43 | 35,010 |
Total | 13,500 | 7.40 | 3,200 | 155,800 | 6.35 | 31,810 | 169,300 | 6.43 | 35,010 |
| | | | | | | | |
Date: February 2022 | | Page 1-15 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 1-9: Proven and Probable Mineral Reserve Statement (Copper)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Area | Proven Mineral Reserves | Probable Mineral Reserves | Proven and Probable Mineral Reserves |
Tonnage (x 1,000 t) | Grade (Cu %) | Cont. Copper (M lbs) | Tonnage (x 1,000 t) | Grade (Cu %) | Cont. Copper (M lbs) | Tonnage (x 1,000 t) | Grade (Cu %) | Cont. Copper (M lbs) |
Phoenix | 17,800 | 0.17 | 70 | 208,300 | 0.17 | 770 | 226,100 | 0.17 | 830 |
Total | 17,800 | 0.17 | 70 | 208,300 | 0.17 | 770 | 226,100 | 0.17 | 830 |
Notes to Accompany Mineral Reserve Tables:
1.Mineral reserves are current as at December 31, 2021. Mineral reserves are reported using the definitions in SK1300. The Qualified Person responsible for the estimate is Mr. Donald Doe, RM SME, Group Executive, Reserves, a Newmont employee.
2.The point of reference for the estimates is the point of delivery to the process facilities.
3.Mineral reserves are reported for Nevada Gold Mines on a 100% basis. Barrick owns a 61.5% joint venture interest, with Newmont owning the remaining 38.5% joint venture interest.
4.Mineral reserves that will be mined using open pit mining methods are constrained within a designed pit shell. Mineral reserves that will be mined by underground mining methods are constrained within conceptual stope designs. Parameters used are summarized in Table 12-1 and Table 12-2.
5.Tonnages are metric tonnes rounded to the nearest 100,000. Gold and silver grades are rounded to the nearest 0.01 gold grams per tonne. Copper grade is in %. Gold and silver ounces and copper pounds are estimates of metal contained in tonnages and do not include allowances for processing losses. Contained (cont.) gold and silver ounces are reported as troy ounces, rounded to the nearest 10,000. Copper is reported as pounds and rounded to the nearest 10 million pounds. Rounding of tonnes and contained metal content as required by reporting guidelines may result in apparent differences between tonnes, grade and contained metal content. Due to rounding, some cells may show a zero (“0”). Totals may not sum due to rounding.
| | | | | | | | |
Date: February 2022 | | Page 1-16 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
1.12.3 Factors That May Affect the Mineral Reserve Estimate
Factors that may affect the mineral reserve estimates include: changes to long-term metal price assumptions; changes in local interpretations of mineralization geometry and continuity of mineralized zones; changes to geological and grade shape and geological and grade continuity assumptions; changes to input parameters used in the pit shells and stope outlines constraining the mineral reserves; changes to the cut-off grades used to constrain the estimates; variations in geotechnical, mining, and processing recovery assumptions; and changes to environmental, permitting and social license assumptions.
1.13 Mining Methods
Open pit mining is conducted using conventional techniques and an Owner-operated conventional truck and shovel fleet. Underground mining is currently conducted using conventional stoping methods, and conventional mechanized equipment.
Nevada Operations personnel and external consultants completed geotechnical studies and provided geotechnical recommendations that form the basis for pit designs. Ground control management plans were developed, and are regularly updated.
The Nevada Operations have hydrological models constructed for key operational areas, used to predict the rate of dewatering and for well-location planning. The models are regularly updated.
Ultimate open pit designs were developed based on pit optimization analysis. The pit limits incorporate geotechnical and hydrological recommendations into final high walls and are designed to include ramps and access to haulage routes to waste rock storage facilities (WRSFs) and processing facilities. Some deposits include phased pit designs which are used to sequence the mining operation. Phases are designed to optimize the economics of the operation and/or provide access to selected ore for blending purposes. Haul road effective widths for two-way travel range from 98–141 ft with a maximum grade of 10%. For single-lane haul roads, a minimum road width of 80 ft could be used for the bottom benches of the pit. Bench heights vary from 20–40 ft, and can be 60 ft where triple-benching is employed. Blast patterns are laid out according to material type using rock type designations.
Underground mining is mechanized, using large-scale equipment. The most common mining methods are a combination of cut-and-fill mining variants with cemented rock (CRF) or paste backfill, and long-hole stoping with, depending on ground conditions, either cemented or uncemented backfill. Depending on the operation, material is loaded into haul trucks and hauled to surface using declines, or hoisted via shafts.
The currently active and proposed waste rock storage facilities (WRSFs) have adequate capacity for the LOM. The management of waste rock is based on categorizing by waste rock types based on analytical parameters, with additional refining of waste polygons based on geologic interpretation.
The open pit production schedules have significant variation in ore delivery over time and there is a high proportion of the ore that is stockpiled after mining and before processing. There are several stockpile options, all of which are based upon the grade of material and varying from leach ore to mill ore. Leach material is generally delivered directly to the leach pads.
| | | | | | | | |
Date: February, 2022 | | Page 1-17 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
The number of loading and hauling units allocated to each deposit varies depending on the operational needs from the open pit mine plans. The equipment list also includes the auxiliary equipment needed to support mining and the re-handling of the ore from the stockpile pad into the mill feeders. Underground equipment requirements include large-scale load–haul–dump (LHD) vehicles and haulage trucks, jumbos, and auxiliary equipment.
The LOM plan assumes 577 Mt of ore and 1,202 Mt of waste will be mined.
1.14 Recovery Methods
The designs of the process facilities design were based on a combination of metallurgical testwork, previous study designs, and previous operating experience. The designs are generally conventional to the gold industry. The Goldstrike autoclave uses a thiosulfate–resin-in-leach process which is not conventional, but is successful in processing high alkaline, preg-robbing ore from the Carlin Complex. The Goldstrike autoclave is planned to be converted to CIL in 2022–2023 when the high alkaline, preg-robbing, low-grade, double refractory stockpiles are consumed.
The gold heap leach process consists of a conventional run-of-mine leach pad, followed by leaching, solution collection, and pumping. Solution is collected in the leach pad drain system and then pumped to activated carbon columns (CIC) where gold loads onto activated carbon. Gold-laden carbon is reclaimed from the CIC circuit and transported to a centralized carbon stripping system where the gold is stripped from the carbon and recovered by electro-winning. Stripped carbon is recycled and reused. The gold heap leach produces doré.
The Phoenix copper leach process consists of a conventional run-of-mine leach pad designed to facilitate the stacking of copper oxide and transition ores as well as the subsequent leaching, solution collection, and pumping. The copper heap leach produces copper cathode.
The Gold Quarry concentrator (formerly referred to as Mill 5) relies on oxide pit, oxide stockpile, low-carbonate sulfide material, and high-carbonate sulfide material. The Gold Quarry concentrator uses a combination of flotation and cyanide leaching to recover gold. Gold recovery from the flotation process is dependent upon the application of the appropriate amount of grinding to liberate the pyrite and enable the sulfide mineral(s) to be selectively floated away from the bulk of the ore. Gold recovery from the carbon-in-leach (CIL) process is typically a function of the ease of solution access to gold particles.
The Gold Quarry roaster (formerly referred to as Mill 6) is fed with refractory ores from open pit and underground ores from Cortez, Gold Quarry, Goldstar, stockpile material and flotation concentrates from the Gold Quarry concentrator. Because the final processing steps are the same as in the oxide mill, the performance of a roasting facility is similarly driven by the same parameters with the addition of sufficient retention time in the roaster in contact with sufficient oxygen to complete the oxidizing process.
The Pipeline mill treats material from the Crossroads/Pipeline open pit, Cortez Pits open pit, Cortez Hills underground, and historical stockpiles derived from mining of the Pipeline and Cortez Hills open pits. The process consists of crushing and grinding, a CIL circuit, carbon stripping and reactivation circuits, and doré refining. The final product is doré.
| | | | | | | | |
Date: February, 2022 | | Page 1-18 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Run-of-mine higher-grade oxide ore from the Turquoise Ridge Surface sources are blended for gold grade, hardness, and carbonate content and fed to the Juniper oxide mill. The process consists of grinding, a CIL circuit, elution and electrowinning. The final product is doré.
The Phoenix solvent extraction–electrowinning (SX/EW) plant is fed with material derived from the Fortitude and Bonanza open pits. The SX plant consists of leaching, solvent extraction, and copper electrolysis, to produce cathode copper.
The Phoenix mill treats material from open pit sources at the Phoenix Complex. The plant has a copper/gold specific flotation system designed to provide concentrate products for sale to an outside smelter. The process consists of crushing and grinding, flotation, conventional CIP processing, to produce copper concentrates. Gold is also recovered by gravity separation.
The Goldstrike autoclave treats material from Goldstrike Betze Open Pit. The process consists of crushing and grinding, pressure oxidation using autoclaves, thiosulfate–resin-in-leach circuits, elution and electrowinning. The autoclave is planned to be converted to CIL in 2022–2023 once all of the high alkaline, preg-robbing, low-grade, double refractory stockpiles are depleted. The final product is doré.
The Sage autoclave treats material from Turquoise Ridge Underground and open pit sources, plus historical stockpiles. The process consists of crushing and grinding, pressure oxidation using autoclaves, a CIL circuit, elution and electrowinning. The final product is doré.
The Goldstrike roaster treats open pit and underground material from numerous sources including the South Arturo open pits, El Niño underground, Goldstrike underground, Goldstrike open pit, historical stockpiles derived from mining of the Goldstrike open pit, Goldstar open pit, Leeville underground, Pete Bajo underground, Exodus underground, Cortez Crossroads/Pipeline open pit, Cortez Hills underground, historical stockpiles derived from mining of the Cortez Hills and Crossroads/Pipeline open pits, and Goldrush underground. The process includes crushing and grinding, roasting, and a roaster CIL circuit. The product is transferred to the Goldstrike autoclave circuit for elution and electrowinning to produce doré.
The major consumables in the gold heap leach facilities are antiscalant, cyanide and lime. The copper heap leach pads use sulfuric acid. The Phoenix SX/EW plant uses sulfuric acid (electrolyte), cobalt, diluent, extractant, diatomaceous earth, clay, and starch. Mill facilities use grinding media, balls for ball mills, lime, cyanide, collector, frother, and hydrogen peroxide. The Goldstrike autoclave requires calcium thiosulfate and resin. Both autoclaves use grinding media, balls for ball mills, lime, and cyanide. The roasters require oxygen, grinding steel, cyanide, lime and sulfur.
Metallurgical facilities comprise nine heap leach facilities, two oxide plants, two flotation plants, two autoclave facilities and two roaster facilities.
Gold recovery from heap leaching is a function of solution application and management, particle size distribution, time, and mineralogy. Cyanide leach kinetics in the heap leach pads is most strongly affected by ore characteristics.
1.15 Infrastructure
The majority of the key infrastructure to support the Nevada Operations mining activities envisaged in the LOM is in place. New infrastructure is required to support the proposed
| | | | | | | | |
Date: February, 2022 | | Page 1-19 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Goldrush operations in the Cortez Complex. A third shaft at the Turquoise Ridge Complex is under construction.
There are nine heap leach pads in the Project area, all of which are actively being leached. There is sufficient capacity in the heap leach pads and planned heap leach pad expansions for LOM planning purposes.
There are 67 WRSFs in the Project area, of which 36 are inactive and undergoing reclamation, and 31 are active. A total of 24 pits are permitted for partial or full waste backfill. There is sufficient capacity in the existing WRSFs and planned WRSF expansions for LOM planning purposes.
There are 19 TSFs in the Project area, of which 11 are inactive and undergoing reclamation, and eight are active. There is sufficient capacity in the active TSFs and planned TSF expansions for LOM planning purposes.
Water supply for processing operations is sourced, depending on the facility, from well fields, TSF reclaim, storm run-off water, and pit dewatering. Potable water is provided by permitted water wells and supporting treatment and infrastructure facilities. The current water sources, assuming similar climate conditions to those experienced by the operations in the past, will be sufficient for the LOM plan.
Water management operations include systems of dewatering wells, water gathering and conveyance facilities, water storage, water use, and various management options for discharge of excess water. Water not used for mining or milling can be pumped to storage reservoirs. Rapid infiltration basins are used to capture storm run-off water to avoid that water coming into contact with mining operations. The NDEP allows selected complexes within the Nevada Operations, through discharge permits, to discharge groundwater from pumping operations to groundwater vis percolation, infiltration, and irrigation. The current water management practices are expected to be applicable for the LOM plan.
There are no accommodation facilities at any of the complexes. Personnel reside in adjacent settlements including Battle Mountain, Carlin, Elko, Golconda, Wells, West Wendover and Winnemucca.
Electrical power for the Carlin, Cortez, Turquoise Ridge, and Phoenix Complexes is obtained via TS Power Plant and from the Western 102 power plant (both of which are owned and operated by NGM) with transmission by NV Energy. Power for Gold Quarry, Long Canyon, and Goldrush is supplied via the Wells Rural Electric Power Company.
1.16 Markets and Contracts
1.16.1 Market Studies
NGM has established contracts and buyers for the gold bullion and copper concentrate and cathode products from the Nevada Operations, and has an internal marketing group that monitors markets for its key products. Together with public documents and analyst forecasts, these data support that there is a reasonable basis to assume that for the LOM plan, that the key products will be saleable at the assumed commodity pricing.
| | | | | | | | |
Date: February, 2022 | | Page 1-20 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
1.16.2 Commodity Pricing
Barrick, as operator of the NGM JV, provides the commodity price guidance. Barrick uses a combination of historical and current contract pricing, contract negotiations, knowledge of its key markets from a long operations production record, short-term versus long-term price forecasts prepared by the company’s internal marketing group, public documents, and analyst forecasts when considering long-term commodity price forecasts.
Higher metal prices are used for the mineral resource estimates to ensure the mineral reserves are a sub-set of, and not constrained by, the mineral resources, in accordance with industry-accepted practice.
The long-term commodity price and exchange rate forecasts are:
Mineral reserves:
•Gold: US$1,200.00/oz;
•Silver: US$16.50/oz;
•Copper: US$2.75/lb;
Mineral resources:
•Gold: US$1,500.00/oz;
•Silver: US$20.50/oz
•Copper: US$3.50/lb.
1.16.3 Contracts
NGM has contracts in place for the majority of the copper concentrate. The terms contained within the concentrate sales contracts are typical and consistent with standard industry practice for high-gold, low-copper concentrates. NGM’s bullion is sold on the spot market, by marketing experts retained in-house by NGM/Barrick. NGM provides Newmont with the date and number of ounces that will be credited to Newmont’s account, and invoices Newmont for how much NGM is owed, such that Newmont receives credits for the ounces (based on the JV interest) and Newmont pays NGM for the ounces. The terms contained within the sales contracts are typical and consistent with standard industry practice and are similar to contracts for the supply of bullion elsewhere in the world.
The largest in-place contracts other than for product sales cover items such as bulk commodities, operational and technical services, mining and process equipment, and administrative support services. Contracts are negotiated and renewed as needed.
1.17 Environmental, Permitting and Social Considerations
1.17.1 Environmental Studies and Monitoring
Baseline and supporting environmental studies were completed to assess both pre-existing and ongoing site environmental conditions, as well as to support decision-making processes during operations start-up. Characterization studies were completed for climate, air quality, hydrology
| | | | | | | | |
Date: February, 2022 | | Page 1-21 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
and surface water quality, hydrogeology, flora, fauna, soils, agriculture and land use, and the socioeconomic environment.
The Goldrush project is situated in a culturally- and biologically sensitive area, with numerous cultural sites and within sage grouse habitat. Major study areas in support of the planned mining operation include air quality, hazardous material and solid waste, noise, waste rock characterization, soils, biological resources, wildlife, special status species, visual and cultural resources, Native American Traditional Values, social and economic values, and environmental justice.
Plans were developed and implemented to address aspects of operations such as waste and fugitive dust management, spill prevention and contingency planning, water management, and noise levels. These plans will be extended to Goldrush as they become operational.
As part of its permitting requirements, NGM has submitted and received approval on numerous PoOs and Reclamation Plans for each area. NGM has additionally submitted and/or provided information to support Environmental Assessments (EA) or Environmental Impact Statements (EIS) for each area containing public lands. The additionally submitted information includes various baseline and supporting studies on various natural resources. Existing operations were reviewed by the BLM and Nevada Division of Environmental Protection Bureau of Mining Regulation and Reclamation (NDEP–BMRR). BLM NEPA analysis under an EA or EIS can result in a Determination of NEPA Adequacy (DNA), Findings of No Significant Impacts (FONSI), or a Record of Decision (ROD). These determinations are issued by the BLM for those operations where PoOs contain public lands. The PoOs are updated and amended, as necessary, to allow for continuation of mining or additional mine development.
1.17.2 Closure and Reclamation Considerations
Initial closure planning is included within all proposals and reclamation plan documents during the permitting process. Closure planning is integrated with mine and reclamation planning to the extent practicable during active operations. Concurrent reclamation of lands as mining progresses is a primary consideration for NGM. Reclamation plans are regularly reviewed and revised at a minimum of every three years to ensure adequate financial assurances have been put in place for required reclamation activities. Approvals are required from both the BLM and NDEP for reclamation and closure plan amendments and bond adjustments.
Various mine facilities are located within the PoO boundaries on both private lands and the federal lands administered by the BLM. Only approved facility disturbance can be constructed within PoO boundaries. All PoO boundaries and private lands within the PoO are under the jurisdiction of the NDEP–BMRR. The reclamation boundaries define limits of approved disturbance for mining within each PoO boundary. A Nevada industry-standard method or Standard Reclamation Cost Estimator (SRCE) model is used by NGM to calculate the liabilities.
NGM currently has posted approximately US$2.14 B in financial assurances in the form of letters of credit and surety bonds to cover mine closure costs. Additionally, there are several trusts associated with closure cost planning.
Estimated closure costs used in the cashflow analysis total US$0.9 B. This cost estimate is based on the actual disturbance.
| | | | | | | | |
Date: February, 2022 | | Page 1-22 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
The Goldrush project will require development of a temporary closure plan, a tentative plan for permanent closure/interim closure plan, a plan of operations that includes a reclamation plan and reclamation surety estimate, and a plan for monitoring the post-closure stability of the site.
1.17.3 Permitting
As part of its permitting requirements, NGM has submitted PoOs and Reclamation Plans for each operation. NGM has submitted and/or provided information to support NEPA evaluation for each area containing public lands. The PoOs are updated and amended as necessary to allow for continuation of mining or additional mine development. The Nevada Operations have the required permits to operate or will be applying for the permits as they are required for mine development.
Additional permits will be required to support planned operations at Goldrush, with about 20 key permits required. The permitting approach assumes off-site transport of ore for processing at Goldstrike and Gold Quarry. Goldrush is going through NEPA review. This will result in completion of an Environmental Impact Statement which will be followed by Record of Decision from the BLM. The start of the NEPA process is completion of baseline studies and submission of a PoO to the BLM.
1.17.4 Social Considerations, Plans, Negotiations and Agreements
Nevada Gold Mines is one of the largest direct employers in the area and also generates significant indirect employment.
Stakeholder engagement is a primary pillar of that strategy and includes participation in local civic activities; city/town council and county commission meetings; serving on boards and committees; town hall meetings; and one-to-one engagement. From this engagement, NGM listens to, and partners with, local organizations to identify a social investment strategy. Education, health, economic development and cultural heritage are key areas for community investments. NGM has also partnered with local law enforcement on public safety initiatives and conservation groups on environmental conservation programs.
Also as part of the community affairs program, NGM engages with 10 tribal communities. Engagement with partner tribes includes regularly-held meetings called “Dialogue Meetings”; tribal council meetings; community committees; one-to-one engagements and sponsorship of several community-driven initiatives. Through this engagement, NGM works with tribal councils to identify and support community priorities in programs aimed at improving community health and well-being, education attainment, cultural heritage preservation, and economic development.
The Cortez Complex, including the Goldrush project, operates on lands traditionally used by the Western Shoshone tribes and bands. As the Goldrush project develops, NGM will hold public meetings (and advertise a local grievance mechanism according to the Grievance Management Procedure) if internal strategy deems appropriate so that citizens in the surrounding areas may come to learn more about the project and express their support or concerns.
| | | | | | | | |
Date: February, 2022 | | Page 1-23 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
1.18 Capital Cost Estimates
Capital costs were based on recent prices or operating data and are at a minimum at a pre-feasibility level of confidence, having an accuracy level of ±25% and a contingency range not exceeding 15%.
Capital costs included funding for infrastructure, pit dewatering, development drilling, and permitting as well as miscellaneous expenditures required to maintain production. Mobile equipment re-build/replacement schedules and fixed asset replacement and refurbishment schedules were included. Sustaining capital costs reflected current price trends.
The LOM capital cost estimate is US$2.6 B (Table 1-10).
Table 1-10: Capital Cost Estimate
| | | | | | | | |
Area | Unit | Value |
Mine | US$ B | 1.3 |
Process | US$ B | 0.8 |
General and administrative | US$ B | 0.2 |
Goldrush pre-production | US$ B | 0.4 |
Total | US$ B | 2.6 |
Note: Numbers have been rounded; totals may not sum due to rounding.
1.19 Operating Cost Estimates
Operating costs were based on actual costs seen during operations and are projected through the LOM plan, and are at a minimum at a pre-feasibility level of confidence, having an accuracy level of ±25% and a contingency range not exceeding 15%.
Historical costs were used as the basis for operating cost forecasts for supplies and services unless there are new contract terms for these items. Labor and energy costs were based on budgeted rates applied to headcounts and energy consumption estimates.
The LOM operating costs are estimated at US$34.9 B (Table 1-11). The average mining costs (open pit and underground) over the LOM are US$10.47/t mined, autoclave costs are US$34.01/t processed, roaster costs are US$24.12/t processed, oxide mill costs are US$10.46/t processed, heap leach costs are US$3.53/t processed, and general and administrative costs (inclusive of transport costs) are US$5.78/t processed.
1.20 Economic Analysis
1.20.1 Economic Analysis
The financial model that supports the mineral reserve declaration is a standalone model that calculates annual cashflows based on scheduled ore production, assumed processing recoveries, metal sale prices, projected operating and capital costs and estimated taxes.
The financial analysis is based on an after-tax discount rate of 5%. All costs and prices are in unescalated “real” dollars. The currency used to document the cashflow is US$.
| | | | | | | | |
Date: February, 2022 | | Page 1-24 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
All costs are based on the 2022 budget. Revenue is calculated from the recoverable metals and long-term metal price and exchange rate forecasts.
Taxes assume a rate of 21% plus the Nevada Net Proceeds Tax of 5% and the Nevada Mining Education Tax.
The economic analysis is based on 100% equity financing and is reported on a 100% project ownership basis. The economic analysis assumes constant prices with no inflationary adjustments. Barrick owns a 61.5% JV interest, with Newmont owning the remaining 38.5% JV interest.
Table 1-11: Operating Cost Estimate
| | | | | | | | |
Item | Units | Value |
Mining | US$B | 18.6 |
Rehandle | US$B | 0.8 |
Autoclaves | US$B | 4.8 |
Roasters | US$B | 5.2 |
Oxide Mill | US$B | 0.4 |
Leach | US$B | 0.6 |
G&A | US$B | 3.3 |
Transport | US$B | 1.1 |
Total | US$B | 34.9 |
Note: Numbers have been rounded; totals may not sum due to rounding.
Within the NGM JV, copper sales are generally in the form of concentrate, which is sold to smelters for further treatment and refining, and cathode. Copper is sold in either concentrate or cathode form. These sales are to third party customers. Generally, if a secondary metal expected to be mined is significant to the NGM JV, co-product accounting is applied. When the NGM JV applies co-product accounting at an operation, revenue is recognized for each co-product metal sold, and shared costs applicable to sales are allocated based on the relative sales values of the co-product metals produced. Generally, if a secondary metal expected to be mined is not significant to the Joint Venture, by-product accounting is applied. As copper and silver production at each of the NGM operations is not significant to the NGM JV, production from copper and silver are accounted for as by-product sales. Revenues from by-product sales are credited by NGM and Barrick as a by-product credit.
For the purposes of showing a complete cashflow analysis for the Nevada Operations as a whole, silver was treated as a by-product credit.
The economic analysis is based on 100% equity financing and is reported on a 100% project ownership basis. The economic analysis assumes constant prices with no inflationary adjustments.
The NPV5% is $4.2 B. Due to the profile of the cashflow, considerations of payback and internal rate of return are not relevant.
A summary of the financial results is provided in Table 1-12.
| | | | | | | | |
Date: February, 2022 | | Page 1-25 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
1.20.2 Sensitivity Analysis
The sensitivity of the Project to changes in metal prices, grade, sustaining capital costs and operating cost assumptions was tested using a range of 20% above and below the base case values (Figure 1-1).
The Project is most sensitive to changes in the metal price, followed by operating cost changes and the least sensitive to capital cost changes. Grade is not shown, as the grade sensitivity mirrors the metal price sensitivity.
Table 1-12: Cashflow Summary Table (100% basis)
| | | | | | | | |
Item | Unit | Value |
Metal prices |
Gold | US$/oz | 1,200 |
Copper | US$/lb | 2.75 |
Silver | US$/oz | 16.5 |
Total ore |
Gold tonnage | Mt | 520 |
Gold grade | g/t | 3.00 |
Copper tonnage | Mt | 226 |
Copper grade | % | 0.17 |
Silver tonnage | Mt | 169 |
Silver grade | g/t | 6.43 |
Gold ounces | Moz | 50 |
Copper pounds | Blb | 0.8 |
Silver ounces | Moz | 35 |
Capital costs | US$B | 2.6 |
Operating cashflow | US$B | 34.2 |
Discount rate | % | 5 |
Free cashflow | US$B | 5.9 |
Net present value | US$B | 4.2 |
Note: Numbers have been rounded; totals may not sum due to rounding. Tonnes are metric tonnes. Barrick owns a 61.5% JV interest, with Newmont owning the remaining 38.5% JV interest. Table 1-12 contains “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, which are intended to be covered by the safe harbor created by such sections and other applicable laws. Please refer to the note regarding forward-looking information at the front of the Report. The cashflow is only intended to demonstrate the financial viability of the Project. Investors are cautioned that the above is based on a high-level mine plan and certain assumptions which may differ from Newmont’s long-term outlook or actual financial results, including, but not limited to commodity prices, escalation assumptions and other technical inputs. For example, Table 1-12 uses the price assumptions stated in the table, including a gold commodity price assumption of US$1,200/oz, which varies significantly from current gold prices and the assumptions that Newmont uses for its long-term guidance. Please be reminded that significant variation of metal prices, costs and other key assumptions may require modifications to mine plans, models, and prospects.
| | | | | | | | |
Date: February, 2022 | | Page 1-26 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 1-1: NPV Sensitivity
Note: Figure prepared by Newmont, 2021. NPV = net present value.
1.21 Risks
The risks associated with the Nevada Operations are generally those expected with open pit and underground mining operations and include the accuracy of the resource models, unexpected geological features that cause geotechnical issues, and/or operational impacts.
Other risks noted include:
•Commodity price increases for key consumables such diesel, electricity, tires and chemicals would negatively impact the stated mineral reserves and mineral resources;
•Labor cost increases or productivity decreases could also impact the stated mineral reserves and mineral resources, or impact the economic analysis that supports the mineral reserves;
•Geotechnical and hydrological assumptions used in mine planning are based on historical performance, and to date historical performance has been a reasonable predictor of current conditions. Any changes to the geotechnical (seismicity) and hydrological assumptions could affect mine planning, affect capital cost estimates if any major rehabilitation is required due to a geotechnical or hydrological event, affect operating costs due to mitigation
| | | | | | | | |
Date: February, 2022 | | Page 1-27 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
measures that may need to be imposed, and impact the economic analysis that supports the mineral reserve estimates;
•The mineral resource estimates are sensitive to metal prices. Lower metal prices require revisions to the mineral resource estimates;
•The LOM plan assumes that new TSFs can be permitted based on envisaged timelines. If the permitting schedule is delayed, this could impact costs and proposed production;
•Updated industry standards for TSFs may have an impact on the envisaged TSF costs;
•The LOM plan assumes that ore is sent to the process facility that will provide optimal results (costs, metallurgical recoveries). Should, for operational reasons, a different process facility be selected, then higher operating costs and/or lower recoveries may result;
•The LOM plan envisages blending of numerous ore sources at the various process facilities. Non-optimal blends could impact operating costs, plant throughputs, and metallurgical recoveries. There may be potential for exceedances on environmental monitoring limits if such blends are not well controlled;
•Stockpiled materials can undergo degradation over time, and the metallurgical recoveries assumed for stockpiled materials may be lower than that assumed in the LOM plan;
•Management of threatened and endangered species may delay permits and increase capital and/or operating costs. Although there are site-specific management plans, either planned or in place, if there is a major impact seen on the populations from mining activities, the environmental permits for the operations could be revised or even revoked. The social license to operate could also be impacted;
•Regulatory approval of the Goldrush project is still pending, and the project is in the EIA process. If conditions are imposed by the regulators as a result of the process, this could impact the project schedule and cost estimates;
•On-highway transport of ore or concentrate could be impacted by changes to regulations on the number of trucks that can be used;
•Exceedances of permit conditions have historically occurred at certain of the process facilities. Should such exceedances recur, there could be social and regulatory impacts to operations, mine plans, and the forecast economic analyses;
•Climate changes could impact operating costs and ability to operate;
•The long-term reclamation and mitigation of the Nevada Operations are subject to assumptions as to closure timeframes and closure cost estimates. If these cannot be met, there is a risk to the costs and timing;
•Newmont is the minority partner in the NGM JV and does not exercise day-to-day control over NGM’s operations;
•Political risk from challenges to the current state or federal mining laws.
| | | | | | | | |
Date: February, 2022 | | Page 1-28 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
1.22 Opportunities
Opportunities include:
•Conversion of some or all of the measured and indicated mineral resources currently reported exclusive of mineral reserves to mineral reserves, with appropriate supporting studies;
•Upgrade of some or all of the inferred mineral resources to higher-confidence categories, such that this higher-confidence material could potentially be converted to mineral reserve estimates;
•Higher metal prices than forecast could present upside sales opportunities and potentially an increase in predicted Project economics;
•NGM holds a significant ground package within the AOI that retains significant exploration potential:
◦Exploration potential around current and historical open pits;
◦Potential for new underground operations proximal to the current mineral resource and mineral reserve estimates, with the support of additional studies.
1.23 Conclusions
Under the assumptions presented in this Report, the Nevada Operations have a positive cashflow, and mineral reserve estimates can be supported.
1.24 Recommendations
As the Nevada Operations are a complex of operating mines, the QP has no material recommendations to make.
| | | | | | | | |
Date: February, 2022 | | Page 1-29 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
2.0 INTRODUCTION
2.1 Registrant
This technical report summary (the Report) was prepared for Newmont Corporation (Newmont) on the Nevada Operations (Nevada Operations or the Project) that are located in Nevada (Figure 2-1).
The Project is operated as a joint venture (JV) through Nevada Gold Mines, LLC (NGM). Barrick Gold Corporation (Barrick) is the JV operator and owns 61.5%, with Newmont owning the remaining 38.5% JV interest.
2.2 Terms of Reference
2.2.1 Report Purpose
The Report was prepared to be attached as an exhibit to support mineral property disclosure, including mineral resource and mineral reserve estimates, for the Nevada Operations in Newmont’s Form 10-K for the year ending December 31, 2021.
Deposits and zones for which mineral resources and mineral reserves are reported are summarized in Table 2-1.
2.2.2 Terms of Reference
The Nevada Operations consist of 10 underground and 12 open pit active mining operations, two autoclave facilities, two roasting facilities, two oxide mills, two flotation plant and five heap leach facilities, forming five major mining/processing complexes centered at Carlin, Cortez, Long Canyon, Phoenix and Turquoise Ridge.
Active open pit mining operations include Crossroads, Gold Quarry, Goldstrike, Goldstar, Long Canyon, Phoenix, Pipeline, and Vista. Two deposits, the Mega Pit at Turquoise Ridge and the South Arturo deposit at Carlin that are planned to be mined using open pit methods, are not currently active, but are planned to be mined in 2022–2023. Active underground mining operations include Cortez Hills underground, Exodus, Goldstrike, El Niño, Leeville, Pete Bajo, Turquoise Ridge Underground, and Vista. Underground exploration development is underway at the Goldrush deposit.
Figure 2-1 shows the locations of the major mining complexes in relation to the JV area of interest (AOI) covers a significant portion of northern Nevada. Note that the AOI area includes ground that is held by third parties and is not part of the NGM mineral title holdings.
| | | | | | | | |
Date: February, 2022 | | Page 2-1 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 2-1: Deposits/Zones Hosting Mineral Resources and Mineral Reserves
| | | | | | | | |
Complex | Deposit/Zone | Mining Method |
Carlin | Emigrant | Open pit |
Exodus | Underground |
Gold Quarry | Open pit |
Goldstar | Open pit |
Goldstrike | Open pit |
Goldstrike | Underground |
Green Lantern | Open pit |
Leeville | Underground |
North Leeville | Underground |
Perry | Open pit |
Pete Bajo | Underground |
Ren | Underground |
Rita K | Underground |
South Arturo | Open pit |
El Niño (South Arturo) | Underground |
Cortez | Cortez Hills Underground (CHUG) | Underground |
Cortez Pits | Open pit |
Crossroads | Open pit |
Gold Acres | Open pit |
Goldrush | Underground |
Pipeline | Open pit |
Robertson | Open pit |
Long Canyon | Phase 1 | Open pit |
Phase 2 | Open pit |
Phase 3 | Underground |
Phoenix | Bonanza | Open pit |
Fortitude | Open pit |
Turquoise Ridge | Mega Cut 25 | Open pit |
Mega Cut 40 | Open pit |
Mega Cut 55 | Open pit |
Turquoise Ridge Underground | Underground |
Vista 8 | Open pit |
Vista 9 | Open pit |
Vista Underground | Underground |
| | | | | | | | |
Date: February, 2022 | | Page 2-2 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 2-1: Mining Complex and Plan of Operations Location Plan
| | | | | | | | |
Date: February, 2022 | | Page 2-3 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Unless otherwise indicated, all financial values are reported in United States (US) currency (US$).
Units may be in either metric or US customary units as identified in the text.
Mineral resources and mineral reserves are reported using the definitions in Subpart 229.1300 – Disclosure by Registrants Engaged in Mining Operations in Regulation S–K 1300 (SK1300).
The Report uses US English.
The Report contains forward-looking information; refer to the note regarding forward-looking information at the front of the Report.
2.3 Qualified Persons
The following Newmont employee serves as the Qualified Person (QP) for the Report:
•Mr. Donald Doe, RM SME., Group Executive, Reserves, Newmont.
Mr. Doe is responsible for all Report Chapters.
2.4 Site Visits and Scope of Personal Inspection
Mr. Doe visited the Nevada Operations on many occasions, most recently on February 5, 2019, to the Carlin Complex. He inspected the underground workings at Leeville and Pete Bajo, viewed the open pit operations, and toured the Gold Quarry roaster.
Mr. Doe performed a site visit in May 5–6, 2021 to the Goldrush project. During that visit he inspected the underground workings, reviewed core, and met with project representatives. Mr. Doe also toured the planned locations for some of the surface infrastructure.
2.5 Report Date
Information in the Report is current as at December 31, 2021.
2.6 Information Sources and References
The reports and documents listed in Chapter 24 and Chapter 25 of this Report were used to support Report preparation.
2.7 Previous Technical Report Summaries
Newmont has not previously filed a technical report summary on the Project.
| | | | | | | | |
Date: February, 2022 | | Page 2-4 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
3.0 PROPERTY DESCRIPTION
3.1 Introduction
The Nevada Operations are centered on the Carlin South Plan of Operations, which is the approximate center of the Area of Interest (AOI), see Figure 2-1 and discussion in Chapter 3.3. The centroid locations of the current Plans of Operations (PoOs) are summarized in Table 3-1.
3.2 Property and Title in Nevada
3.2.1 Mineral Title
Federal (30 USC and 43 CFR) and Nevada (NRS 517) laws concerning mining claims on Federal land are based on an 1872 Federal law titled “An Act to Promote the Development of Mineral Resources of the United States.” Mining claim procedures still are based on this law, but the original scope of the law has been reduced by several legislative changes.
The Mineral Leasing Act of 1920 (30 USC Chapter 3A) provided for leasing of some non-metallic materials; and the Multiple Mineral Development Act of 1954 (30 USC Chapter 12) allowed simultaneous use of public land for mining under the mining laws and for lease operation under the mineral leasing laws. Additionally, the Multiple Surface Use Act of 1955 (30 USC 611-615) made “common variety” materials non- locatable; the Geothermal Steam Act of 1970 (30 USC Chapter 23) provided for leasing of geothermal resources; and the Federal Land Policy and Management Act of 1976 (the “BLM Organic Act,” 43 USC Chapter 35) granted the Secretary of the Interior broad authority to manage public lands. Most details regarding procedures for locating claims on Federal lands have been left to individual states, providing that state laws do not conflict with Federal laws (30 USC 28; 43 CFR 3831.1).
Mineral deposits are located either by lode or placer claims (43 CFR 3840). The locator must decide whether a lode or placer claim should be used for a given material; the decision is not always easy but is critical. A lode claim is void if used to acquire a placer deposit, and a placer claim is void if used for a lode deposit. The 1872 Federal law requires a lode claim for “veins or lodes of quartz or other rock in place” (30 USC 26; 43 CFR 3841.1), and a placer claim for all “forms of deposit, excepting veins of quartz or other rock in place” (30 USC 35). The maximum size of a lode claim is 1,500 ft (457 m) in length and 600 ft (183 m) in width, whereas an individual or company can locate a placer claim as much as 20 acres (8 ha) in area.
Claims may be patented or unpatented. A patented claim is a lode or placer claim or mill site for which a patent has been issued by the Federal Government, whereas an unpatented claim means a lode or placer claim, tunnel right or mill site located under the Federal (30 USC) act, for which a patent has not been issued.
| | | | | | | | |
Date: February, 2022 | | Page 3-1 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 3-1: Operations Plan of Operations Centroid Location Summary Table
| | | | | | | | | | | |
Plan Of Operations Name | Easting | Northing | Projection Datum |
Arturo | 547693.67 | | 4542375.40 | | UTM NAD83 Zone 11N |
Bootstrap | 549530.93 | | 4540070.80 | | UTM NAD83 Zone 11N |
Carlin | 558233.17 | | 4528248.53 | | UTM NAD83 Zone 11N |
Cortez | 527007.17 | | 4451450.13 | | UTM NAD83 Zone 11N |
Dee | 546666.01 | | 4542000.35 | | UTM NAD83 Zone 11N |
Emigrant | 587023.17 | | 4495607.30 | | UTM NAD83 Zone 11N |
Genesis-Bluestar | 553286.53 | | 4531560.79 | | UTM NAD83 Zone 11N |
Gold Quarry | 567325.95 | | 4514448.36 | | UTM NAD83 Zone 11N |
Goldstrike | 551906.11 | | 4537120.53 | | UTM NAD83 Zone 11N |
Phoenix | 489152.32 | | 4483634.77 | | UTM NAD83 Zone 11N |
Leeville | 556455.63 | | 4531494.14 | | UTM NAD83 Zone 11N |
Long Canyon | 710085.96 | | 4537424.11 | | UTM NAD83 Zone 11N |
Rain | 583602.96 | | 4495804.12 | | UTM NAD83 Zone 11N |
Turquoise Ridge | 482164.33 | | 4560820.78 | | UTM NAD83 Zone 11N |
Twin Creeks | 487331.39 | | 4566477.34 | | UTM NAD83 Zone 11N |
3.2.2 Surface Rights
About 85% of the land in Nevada is controlled by the Federal Government; most of this land is administered by the US Bureau of Land Management (BLM), the US Forest Service (USFS), the US Department of Energy, or the US Department of Defense. Much of the land controlled by the BLM and the USFS is open to prospecting and claim location. The distribution of public lands in Nevada is shown on the BLM “Land Status Map of Nevada” (1990) at scales of 1:500,000 and 1:1,000,000.
Bureau of Land Management regulations regarding surface disturbance and reclamation require that a notice be submitted to the appropriate BLM Field Office for exploration activities in which five acres or fewer are proposed for disturbance (43 CFR 3809.1-1 through 3809.1-4). A Plan of Operations (PoO) is needed for all mining and processing activities, plus all activities exceeding five acres of proposed disturbance. A PoO is also needed for any bulk sampling in which 1,000 or more tons of presumed mineralized material are proposed for removal (43 CFR 3802.1 through 3802.6, 3809.1-4, 3809.1-5). The BLM also requires the posting of bonds for reclamation for any surface disturbance caused by more than casual use (43 CFR 3809.500 through 3809.560). The USFS has regulations regarding land disturbance in forest lands (36 CFR Subpart A). Both agencies also have regulations pertaining to land disturbance in proposed wilderness areas.
3.2.3 Water Rights
In the State of Nevada, “the water of all sources of water supply within the boundaries of the State whether above or beneath the surface of the ground, belongs to the public” (NRS 533.025). Furthermore, “except as otherwise provided in NRS 533.027 and 534.065, any person who wishes to appropriate any of the public waters, or to change the place of diversion, manner of use or place of use of water already appropriated, shall, before performing any work in
| | | | | | | | |
Date: February, 2022 | | Page 3-2 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
connection with such appropriation, change in place of diversion or change in manner or place of use, apply to the State Engineer for a permit to do so” (NRS 533.325).
3.2.4 Government Mining Taxes, Levies or Royalties
The state of Nevada imposes a 5% net proceeds tax on the value of all minerals severed in the State. This tax is calculated and paid based on a prescribed net income formula.
A Nevada Education funding tax, AB 495, was passed in July 2021, and is based on gold and silver gross revenue and is calculated as follows:
•First $20 M of gross revenue: exempt;
•>$20 M to $150 M of gross revenue: taxed at a flat rate of 0.75%;
•>$150 M of gross revenue: taxes at a flat rate of 1.1%.
3.3 Ownership
NGM is a JV between Barrick and Newmont. Barrick is the JV operator and has a 61.5% interest, with Newmont owning the remaining 38.5% interest. The JV area of interest (AOI) covers a significant portion of northern Nevada (Figure 3-1). Barrick operates the JV.
3.4 Joint Ventures
On 11 March, 2019, Barrick and Newmont announced the formation of the NGM JV. Newmont, Barrick, and their respective affiliates that held properties in the AOI contributed to NGM the respective rights, titles and interests in, to, or under, all properties located in the AOI and any other assets, properties or rights located in Nevada.
Barrick has the right to appoint three NGM Board members; Newmont can appoint two.
Newmont and Barrick each have a right of first refusal over any proposed transfer by the other JV participant of its membership interest in NGM, other than transfers to a wholly-owned subsidiary of the transferring JV participant.
The JV agreement requires that Newmont and Barrick purchase 100% of the refined doré that NGM produces on a pro rata basis, according to the individual company’s JV interest.
| | | | | | | | |
Date: February, 2022 | | Page 3-3 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 3-1: NGM Area of Interest
| | | | | | | | |
Date: February, 2022 | | Page 3-4 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Newmont and Barrick excluded certain development and exploration properties that the companies held within the AOI from the JV; these included Newmont’s Fiberline and Mike projects, and Barrick’s Fourmile project. The JV has a mechanism for the potential contribution of the excluded properties to NGM in the future.
3.5 Agreements
A number of agreements exist with federal, state, and third-party entities and these are monitored using a land management database. The data managed includes contractual obligations, leases, associated payments, parties to agreements, and locations and details of the properties that the agreements cover. All mining leases and subleases are managed and reviewed on a monthly basis and all payments and commitments are paid as required by the specific agreements.
The database covers both monetary obligations such as lease payments and non-monetary obligations such as third-party required reporting, work commitments, taxes, and contract expiry dates. The agreements that NGM has with third parties within the PoOs are monitored using this database.
Across the AOI, there are currently 294 agreements that have been concluded, and 168 easements that are in place.
3.6 Mineral Title
The Nevada Operations currently includes 15 operations PoOs and eight exploration PoOs. The area includes private land (surface and minerals) owned or controlled by NGM, and land owned by the federal government that is administered by the BLM.
NGM provided a claims list, fee property list, and location plans for the PoOs. The areas in the claims tables that follow reflect the staked claim area; the areas have not been modified for claim overlaps. In some instances, where the same claims are reported within two or more PoOs; the claims are included in the claims list for the individual PoO for completeness, but have been removed for area and claim number totaling purposes.
Within the operations PoO areas are the claims summarized in Table 3-2, which collectively total 9,205 lode, millsite, placer and patented claims covering an area of 163,214.40 acres. Within the exploration PoO areas are the claims summarized in Table 3-3, which collectively total 2,180 lode, millsite, placer and patented claims covering an area of 43,363.94 acres. Between the operations and the exploration PoOs, NGM holds a total of 11,385 claims covering an area of 206,578.34 acres (Table 3-4). Figure 3-2 to Figure 3-6 show the locations of the major PoOs that host the mineral reserves.
In addition, NGM holds a number of fee properties, within the operations and exploration PoOs (Table 3-5 and Table 3-6). Collectively, these cover an area of 78,620.56 acres.
Patented ground or claims are surveyed by a certified mineral surveyor, and appropriate monuments are placed in the ground. Each unpatented claim is marked on the ground and does not require a mineral survey.
| | | | | | | | |
Date: February, 2022 | | Page 3-5 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Unpatented mining and mill site claims that are located on public lands are held subject to the paramount title of the federal government. The claims are maintained on an annual basis, and do not expire as long as the maintenance fee payments are timely filed with the BLM.
Patented and fee lands require annual payment of tax assessments to the relevant Nevada county.
| | | | | | | | |
Date: February, 2022 | | Page 3-6 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 3-2: Claims Summary Table, Operations PoOs
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
PoO Name | Lode | Millsite | Placer | Patented | Total |
Claims | Acres | Claims | Acres | Claims | Acres | Claims | Acres | Claims | Acres |
Arturo | 236 | 4,539.04 | 98 | 453.32 | | | | | 334 | 4,992.36 |
Bootstrap | 123 | 2,399.72 | | | | | 13 | 253.42 | 136 | 2,653.14 |
Carlin | 102 | 1,959.89 | | | | | | | 102 | 1,959.89 |
Cortez | 2,917 | 55,998.37 | 555 | 2,563.30 | 2 | 320.00 | 145 | 1,020.98 | 3,619 | 59,902.65 |
Dee | 343 | 6,552.88 | 102 | 473.28 | | | | | 445 | 7,026.16 |
Genesis–Bluestar | 203 | 3,856.97 | 3 | 12.92 | | | | | 206 | 3,869.89 |
Gold Quarry | 309 | 6,346.75 | 225 | 1,125.00 | | | | | 534 | 7,471.75 |
Goldrush (proposed PoO) | 1,047 | 20,847.65 | 17 | 337.85 | | | | | 1,064 | 21,185.50 |
Goldstrike | 245 | 4,555.88 | 52 | 249.71 | | | 60 | 1,016.87 | 357 | 5,822.46 |
Leeville | 45 | 912.71 | | | | | | | 45 | 912.71 |
Long Canyon | 734 | 14,478.43 | | | | | | | 734 | 14,478.43 |
Phoenix | 533 | 10,940.85 | 60 | 300.00 | 21 | 2,680.66 | 228 | 2,441.20 | 842 | 16,362.71 |
Rain–Emigrant | 139 | 2,809.45 | | | | | | | 139 | 2,809.45 |
Ren | 91 | 1,596.73 | | | | | | | 91 | 1,596.73 |
Rossi | 388 | 7,585.40 | 22 | 103.32 | | | 11 | 221.25 | 421 | 7,909.97 |
Turquoise Ridge | 803 | 16,254.76 | 40 | 194.94 | | | | | 843 | 16,449.70 |
Sub-total Operations | 8,258 | 161,635.48 | 1,174 | 5,813.64 | 23 | 3,000.66 | 457 | 4,953.72 | 9,912 | 175,403.50 |
Claims reported in two PoOs; second claim listing area excluded | 583 | 11,348.61 | 101 | 466.24 | | | | | 684 | 11,814.85 |
Claims reported in three PoOs; second and third claim listing areas excluded | 23 | 374.25 | | | | | | | 23 | 374.25 |
Total Operations | 7,652 | 149,912.62 | 1,073 | 5,347.40 | 23 | 3,000.66 | 457 | 4,953.72 | 9,205 | 163,214.40 |
| | | | | | | | |
Date: February, 2022 | | Page 3-7 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 3-3: Claims Summary Table, Exploration PoOs
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
PoO Name | Lode | Millsite | Placer | Patented | Total |
Claims | Acres | Claims | Acres | Claims | Acres | Claims | Acres | Claims | Acres |
Antler Peak | 5 | 103.30 | | | | | | | 5 | 103.30 |
Chevas | 108 | 2,231.28 | | | | | | | 108 | 2,231.28 |
Chimney North | 1,196 | 24,659.14 | | | | | | | 1,196 | 24,659.14 |
Emigrant | 47 | 970.75 | | | | | | | 47 | 970.75 |
High Desert | 118 | 2,362.31 | | | | | 4 | 62.46 | 122 | 2,424.77 |
Hilltop | 189 | 3,637.36 | | | 25 | 510.96 | 18 | 315.02 | 232 | 4,463.34 |
Robertson | 445 | 7,938.58 | | | | | 9 | 168.86 | 454 | 8,107.44 |
Woodruff Creek | 203 | 4,135.56 | | | | | | | 203 | 4,135.56 |
Sub-total Exploration | 2,311 | 46,038.28 | 0 | 0.00 | 25 | 510.96 | 31 | 546 | 2,367 | 47,096 |
Claims reported in two PoOs; second claim listing area excluded | 174 | 3,483.72 | | | | | | | 174 | 3,483.72 |
Claims reported in three PoOs; second and third claim listing areas excluded | 13 | 247.92 | | | | | | | 13 | 247.92 |
Exploration Total | 2,124 | 42,363.94 | 0 | 0.00 | 25 | 510.96 | 31 | 546.34 | 2,180 | 43,363.94 |
Note: Within the Robertson PoO, there were five claims in the claims table that had separate entries for each different owner, where the claims were entered into the NGM database as having four registered owners. The claims table was adjusted to reflect a single claim rather than multiple claims.
Table 3-4: Claims Totals
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
PoO Name | Lode | Millsite | Placer | Patented | Total |
Claims | Acres | Claims | Acres | Claims | Acres | Claims | Acres | Claims | Acres |
Total Operations | 7,652 | 149,912.62 | 1,073 | 5,347.40 | 23 | 3,000.66 | 457 | 4,953.72 | 9,205 | 163,214.40 |
Total Exploration | 2,124 | 38,669.28 | 0 | 0.00 | 0 | 0.00 | 31 | 546.34 | 2,180 | 43,363.94 |
Grand Total | 9,776 | 188,581.90 | 1,073 | 5,347.40 | 23 | 3,000.66 | 488 | 5,500.06 | 11,385 | 206,578.34 |
| | | | | | | | |
Date: February, 2022 | | Page 3-8 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 3-5: Operations Fee Property Totals
| | | | | |
Plan of Operation | Acres |
Arturo | 37.38 |
Bootstrap | 887.64 |
Carlin | 3,347.22 |
Cortez | 2,782.84 |
Dee | 0.00 |
Genesis–Bluestar | 3,980.60 |
Gold Quarry | 8,187.98 |
Goldrush | 518.48 |
Goldstrike | 8,089.36 |
Leeville | 137.60 |
Long Canyon | 14,774.62 |
North Area Leach | 1,705.38 |
Phoenix | 6,828.60 |
Rain–Emigrant | 3,455.88 |
Ren | 0.00 |
Rossi | 0.00 |
Robertson | 0.00 |
Turquoise Ridge | 5,585.51 |
Total | 60,319.10 |
| | | | | | | | |
Date: February, 2022 | | Page 3-9 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 3-6: Exploration Fee Property Totals
| | | | | |
Plan of Operations | Acres |
Antler Peak | 3,382.38 |
Chevas | 1,020.40 |
Chimney North | 0.00 |
Emigrant | 1,075.24 |
Four Corners | 1,301.04 |
High Desert | 54.98 |
Hilltop | 3,956.94 |
Mike | 242.99 |
Pearl | 1,992.87 |
Richmond | 1,989.43 |
Robertson | 0.0 |
Tara | 355.68 |
Woodruff Creek | 2,929.51 |
Total | 18,301.46 |
| | | | | | | | |
Date: February, 2022 | | Page 3-10 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 3-2: Carlin Complex Plans of Operation
| | | | | | | | |
Date: February, 2022 | | Page 3-11 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 3-3: Cortez Complex Plans of Operation
| | | | | | | | |
Date: February, 2022 | | Page 3-12 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 3-4: Long Canyon Complex Plan of Operations
| | | | | | | | |
Date: February, 2022 | | Page 3-13 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 3-5: Phoenix Complex Plan of Operation
| | | | | | | | |
Date: February, 2022 | | Page 3-14 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 3-6: Turquoise Ridge Complex Plans of Operation
| | | | | | | | |
Date: February, 2022 | | Page 3-15 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
3.7 Surface Rights
NGM holds all necessary surface rights for the current mining operations. Additional surface rights will be required, for future mining projects.
The Goldrush PoO is currently moving through the National Environmental Policy Act (NEPA) process (see discussion in Chapter 17.4.2).
3.8 Water Rights
NGM currently maintains a combination of approximately 1,250 active surface and groundwater rights within 38 hydrographic basins. Permitted manners of use include stockwater, mining and milling, storage, irrigation, environmental, quasi-municipal, commercial, industrial, wildlife, domestic, construction, and dewatering. These water rights are required by NRS 533 for all water management activities at NGM’s various mining and ranching operations.
NGM holds all necessary water rights for the LOM plan envisaged in this Report.
3.9 Royalties
3.9.1 Claims Royalties
There are numerous royalties that pertain to the active mines within the Nevada Operations. Royalty payments vary, as the payments depend upon actual tonnages mined, the amount of gold recovered from that mined material, the deposit being mined, the receiving entity, and the type of royalty. A number of the claims have inactive royalties attached, which are not currently triggered as the claims are not being mined.
The major royalties for each deposit are summarized in Table 3-7. Royalties listed can pertain to single claim, or to a group of claims, and therefore can apply to only a portion of a deposit, or to the overall deposit area.
3.9.2 NGM Royalty
In connection with the formation of Nevada Gold Mines, each of Barrick and Newmont was granted a 1.5% net smelter returns royalty over the respective properties they contributed to the NGM JV.
For the properties contributed by Barrick, the 1.5% net smelter returns royalty is payable on all gold produced from these properties after 47,301,000 ounces of gold have been produced from the properties from and after July 1, 2019. For the properties contributed by Newmont, the 1.5% net smelter returns royalty is payable on all gold produced from these properties after 36,220,000 ounces of gold have been produced from the properties from and after July 1, 2019, and (ii) a separate and independent net smelter returns royalty on all copper produced from the Properties after 1,520,000,000 pounds of copper have been produced from these Properties from and after the July 1, 2019.
Each of these “retained royalties” is only payable once the aggregate production from the properties subject to the royalty exceeds the publicly-reported Mineral Resources and Mineral Reserves as of December 31, 2018.
| | | | | | | | |
Date: February, 2022 | | Page 3-16 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 3-7: Royalties
| | | | | |
Deposit | Royalty |
South Arturo | Franco-Nevada U.S. Corp.: South Arturo, 4–9% variable GSR |
Cortez | Ward: Cortez, 5% NRR |
Prochnau: Cortez, 2% NRR |
Royal Gold: Cortez, 0.71250075% + sliding scale 0.4–5% GSR; 3.75% NVR; 0.7125075% and a sliding scale 0.72–9% GSR |
Rio Tinto: Cortez, 0–3% sliding scale royalty based on gold price on 40% of production |
Idaho Royalty Holders: Cortez, 1.28595% ORR, 0.78749925% GR |
Denver Mining Finance Company: Cortez, 3.75% GR |
Royal Crescent Valley: Cortez, 0.8545875% NVR; 1.25% NVR |
Kelly and Moloney: Cortez, $0.5–$0.65/ton sliding scale (based on ore type and price) |
Duerr & Prochnau: Cortez, 2% NSR |
McCoy: Cortez, 4% NSR on hard rock and 1/6 production on coal, oil and gas; geothermal production royalty |
Filippini: Cortez, 5% NSR on hard rock and 1/6 production on coal, oil and gas; geothermal production royalty |
Robertson: Cortez, 4% NSR on hard rock and 1/6 production on coal, oil and gas; geothermal production royalty |
Genesis–Bluestar | RG Royalties LLC: Genesis-Bluestar, 2% NVR |
Franco-Nevada U.S. Corp.: Genesis–Bluestar, 6% NPI; 5% NPI; 4% NSR |
Goldstrike | Franco-Nevada U.S. Corp.: Goldstrike, 2–4% NSR; 2.4–6% NPI |
Royal Gold Inc.: Goldstrike, 1% NSR |
Rhoads: Goldstrike, 5% NSR (net 2.5%) |
Kennecott Nevada Company: Goldstrike, 5% NSR |
White: Goldstrike, 9% NPI |
Bilbao, Alcor Inc., Alloyed Associates, Inc: Goldstrike, 5% NSR |
Gold Quarry | Various: Gold Quarry, 8% NSR and 62.7% of 8% NSR Mill and 68.7% of 8% NSR Leach |
Tomera: Gold Quarry, 50% of 8% NSR |
Jones: Gold Quarry, 50% of 8% NSR |
Pacini: Gold Quarry, 1% NSR |
Ash Danko Hanna & Co: Gold Quarry, 22.5% of 18% NSR |
Roy Ash: Gold Quarry, 22.5% of 18% NSR |
Franco-Nevada U.S. Corp.: Gold Quarry, 40.5% of 18% NSR |
Gold Quarry Royalty Trust: Gold Quarry, 4.5% of 18% NSR |
Goldrush | Idaho Royalty Holders: 1.28595% ORR |
Keleher and McLeod et al: 2-5 at 8.33% Variable NSR based on Gold Price |
Teck American Incorporated: 10% NPR from Production |
Englebright: 2% NPR |
Genesis Gold: 3% NRR |
Steiner: 0.2083% - 0.4167% Variable Production Royalty based on Gold Price |
Royal Gold: 1% Net Reserves |
Damele: 3% NSR |
Royal Gold: 15%NPI |
Idaho Resources Corporation: 0.75% GVR |
TeckCominco: 3% NSR |
| | | | | | | | |
Date: February, 2022 | | Page 3-17 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
| | | | | |
Deposit | Royalty |
Leeville | RG Royalties LLC: Carlin, Leeville 2% NVR |
EMX Inc. (Bullion Monarch Mining Inc.): Leeville, 1% GSR |
Quest U.S.A. Resources, Inc., et al: Leeville, 1% NSR (unpatented); 0.775% NSR (patented) |
Long Canyon | Pittston Mineral Ventures International, Ltd: Long Canyon, 3% NSR |
Mobil Exploration: Long Canyon, 0.15625% NSR |
Phoenix | Flowery Gold Mines Company: Phoenix, 3% NVR capped at $50,000 |
Rain–Emigrant | Premier Gold: Emigrant/Rain, 1.5% NSR |
Premier Gold/Boyack/Montrose: Rain/Emigrant 2.5% NSR |
Boyack: Rain, 1% NSR |
Tomera: Rain, 3% GPR |
Jay Valcarce: Emigrant net 0.625% NSR |
Tomera Stonehouse 50% and Tomera Clan 50%: Emigrant, net 2.5% NSR |
Ren | VEK: Ren, 3–5% NSR based on PPI |
Wallace: Ren, 3.5% NPR |
Weiss: Ren, 4% GPR |
Robertson | Idaho Royalty Holders: 1.28595% ORR |
Billie Filippini: 3% GR |
Northern Nevada Au, Inc.: 4% GR |
Turquoise Ridge Complex | RG Royalties LLC: 2% based on production |
UMETCO Minerals: 2% NSR |
Note: Royalties listed can pertain to single claim, to a group of claims, and therefore can apply to only a portion of a deposit, or to the overall deposit area. There is a process for Premier Gold to assign the royalty interests in Rain–Emigrant to i-80 Gold; however the process is not complete, and Premier Gold remains the official royalty holder. GSR = Gross Smelter Royalty; NRR = Net Revenue Royalty; NPR = Net Profit Royalty; NSR = Net Smelter Royalty; NVR = Net Value Royalty; NPI = Net Profit Interest; GPR = Gross Proceeds Royalty; NPR = Net Proceeds Royalty; GR = Gross Royalty; ORR = Over Riding Royalty; PPI = Producer Price Index; GVR = Gross Value Royalty.
3.9.3 Nevada State Royalty
The State of Nevada levies royalties and taxes as outlined in Chapter 3.2.4.
3.10 Encumbrances
Permitting and permitting conditions are discussed in Chapter 17.9 of this Report. The operations as envisaged in the LOM plan are either fully permitted, or the processes to obtain permits are well understood and similar permits have been granted to the operations in the past, such as tailings storage facility (TSF) raises.
3.11 Violations and Fines
NGM advised the QP that as at December 31, 2021, no material violations or fines were imposed during 2021 by any regulatory authority that would affect the planned LOM for the Nevada Operations as presented in this Report.
| | | | | | | | |
Date: February, 2022 | | Page 3-18 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
3.12 Significant Factors and Risks That May Affect Access, Title or Work Programs
To the extent known to the QP, there are no other known significant factors and risks that may affect access, title, or the right or ability to perform work on the properties that comprise the Nevada Operations that are not discussed in this Report.
| | | | | | | | |
Date: February, 2022 | | Page 3-19 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
4.0 ACCESSIBILITY, CLIMATE, LOCAL RESOURCES, INFRASTRUCTURE AND PHYSIOGRAPHY
4.1 Physiography
The Nevada Operations are within the Great Basin, a part of the Basin and Range geologic province, which is dominated by north–south-trending mountain ranges, flanked by flat, arid valleys that may host playa lakes.
Operations are located between elevations of about 4,400–6,800 ft above mean sea level.
Vegetation is typically sparse, and can include shrubs such as sagebrush, rabbitbrush, and a variety of grasses. Juniper trees, pinion pine, and mountain mahogany can be found at higher elevations.
The most common current land use is for livestock grazing.
4.2 Accessibility
The Nevada Operations are bisected by Interstate 80 (I-80), which provides access to most of the Project area (refer to Figure 2-1).
Access for the Carlin Complex is generally from Elko 26 miles west on I-80 to Carlin which is the closest town to the mine sites. In addition, various alternate access routes use Nevada State Route 766, and Elko and Eureka County roads. These roads are well maintained, and most are paved.
The Cortez Complex is reached by travelling approximately 32 miles east from the town of Battle Mountain on the I-80. Alternative access is from Elko, Nevada, approximately 45 miles west to the Beowawe exit, then approximately 35 miles south on Nevada State Route 306, which extends southward from I-80.
The Long Canyon Complex is accessed from either the I-80 east-bound route through Wells or I-80 west-bound through Wendover, with the main entrance just off the Oasis/Montello interchange. The mine area is within one mile of the freeway with the pit area about four miles west.
The Phoenix Complex is accessed from I-80 at Battle Mountain, traveling approximately 12 miles south on the paved Nevada State Route 305, and then west a short distance on a paved/gravel county access road.
The Turquoise Ridge Complex is accessed from a turnoff at the settlement of Golconda, 25 miles east of Winnemucca, then following a paved road for a further 25 miles, and thereafter by an improved gravel road to the mine gates. It is then 10 miles to the west mine gate and 25 miles to the east mine gate.
The AOI is crossed by a network of gravel roads, providing easy access to various portions of the mining complexes and exploration areas. The majority of the roads are suitable for all-weather conditions; however, in extreme winter conditions, roads may be closed for snow removal.
| | | | | | | | |
Date: February, 2022 | | Page 4-1 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
The Union Pacific Rail line runs parallel to I-80. NGM operates the Dunphy Rail Terminal, which is located 27 miles west of Carlin, for the transportation of bulk commodities such as lubricants, fuel, and ball mill consumables. These bulk commodities are road-transported from the Dunphy Rail Terminal to each site using commercial trucking services.
Elko is serviced by commercial flights to Salt Lake City, Utah.
4.3 Climate
The Nevada Operations are located in the high desert region of the Basin and Range physiographic province. There are warm summers and generally mild winters; however, overnight freezing conditions are common during winter.
Precipitation averages six inches per year, primarily derived from snow and summer thunderstorms. Typically, the months with the greatest precipitation are March, May and November. During the winter months at elevations above about 5,500 ft above sea level, precipitation generally occurs as snow. Evaporation is estimated at 42–44 inches per year.
Operations are conducted year-round.
4.4 Infrastructure
The Nevada Operations are located in a major mining region and local resources including labor, water, power, natural gas, and local infrastructure for transportation of supplies are well established. Mining has been an active industry in northern Nevada for more than 150 years. Elko (pop. 20,300) is a local hub for mining operations in northern Nevada and services necessary for mining operations are readily available.
There are adequate schools, medical services and businesses to support the work force. A skilled and semi-skilled mining workforce has been established in the region as a result of on-going mining activities. Workers live in the surrounding communities.
The Nevada Operations currently have all infrastructure in place to support mining and processing activities (see also discussions in Chapter 13, Chapter 14, and Chapter 15 of this Report). These Report chapters also discuss water sources, electricity, personnel, and supplies.
| | | | | | | | |
Date: February, 2022 | | Page 4-2 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
5.0 HISTORY
A summary of the exploration and development history of the Nevada Operations from 1959 onwards is provided in Table 5-1.
Historical mining and exploration activity in the period from 1860–1950 included small underground and surface mines exploiting gold, copper, lead, antimony, barite and turquoise. Modern exploration activity by Newmont and Barrick and their predecessor companies, commenced in the late 1950s.
Table 5-1: Exploration and Development History Summary Table, Carlin Complex
| | | | | | | | |
Year | Operator | Comment |
1959 | American Exploration & Mining Co. (AMEX) | Wholly-owned US subsidiary of Placer Development Ltd. (subsequently Placer Dome Inc. (Placer Dome) Lease-option agreement on the properties of the Cortez Metals Co. Explored mine workings and surrounding area. |
American Smelting and Refining Company (Asarco) | Purchased claims in Copper Canyon area from US Government |
1961 | Newmont | Evaluated Bluestar mine and Maggie Creek claims |
1962 | Atlas Minerals (Atlas) | Discovered low-grade gold mineralization in Goldstrike area |
1962–1964 | Duval Corporation (Duval) | Joint ventured Copper Canyon land package from Asarco; property transferred outright in 1964 |
Newmont | Explored jasperoid outcrops located 4.5 km southeast of Bluestar, subsequently delineating the Carlin deposit |
1963 | AMEX | Joint venture with Idaho Mining Corp |
1964 | AMEX | Formed the Cortez Joint Venture (Cortez JV) with the added participation of the Bunker Hill Co., Vernon F. Taylor, Jr., and Webb Resources Inc. |
1965 | Newmont | Commenced mining operations at Carlin |
1966 | USGS | Noted anomalous gold in altered outcrops at the base of the Cortez Range |
Cortez JV | Discovered Cortez deposit |
1966–1978 | Duval | Commenced copper and gold mining at Copper Canyon feeding a heap leach and mill. Converted mill to gold only in 1976. |
1969 | Cortez JV | Exploration drilling in Gold Acres area Construction of Cortez Mill No. 1 |
1972 | Newmont | Acquired Bluestar and Bootstrap deposits |
1974 | Nevada Syndicate | Outlined shallow mineralization in the Long Lac and Winston areas |
1975–1977 | Polar Resources (Polar)/Pancana Minerals Ltd (Pancana) | Delineated the Number 9 deposit and several low-grade zones within the Goldstrike intrusion to the east of Nevada Syndicate property. From 1975 to 1977, Polar and Pancana operated a small open pit and heap leach |
1976 | Cortez JV | Discovered Horse Canyon deposit |
1977 | Newmont | Northstar deposit discovered. Mill 1 in operation |
1978 | Western States Minerals Corporation (Western States) | Entered into a JV with Pancana. Open pit mining operations continued, with the bulk of the production from oxidized zones, chiefly from the Long Lac, Bazza, and West Bazza deposits, plus some production from deposits within the Goldstrike intrusion |
Duval | Commenced mining of Tomboy and Minnie deposits |
1980 | Newmont | Emigrant and Gold Quarry deposits discovered |
Early 1980s | Duval | Discovered Northeast Extension (NEX), Upper Fortitude, and Lower Fortitude deposits |
| | | | | | | | |
Date: February, 2022 | | Page 5-1 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
| | | | | | | | |
Year | Operator | Comment |
1982 | Western States | Post deposit discovered |
1984 | First Mississippi Corporation/FRM Minerals Inc. | Purchases Getchell property. |
Gold Fields Mining Corporation (Gold Fields) | Discovers Chimney Creek gold deposit. |
1985 | Newmont | Commissions Mill 2 at Gold Quarry |
Duval | Battle Mountain created to hold assets in Copper Canyon area |
1986 | Western States | Deep Post deposit discovered |
First Mississippi Corporation/FRM Minerals Inc. | Heap leaching of historic Getchell dumps, drill programs to identify additional mineralization in historic workings. Completed feasibility study on Getchell deposit. |
1986–1987 | American Barrick Resources Corporation (American Barrick) | Acquired Western States, and acquired Pancana’s interests in the Goldstrike area |
1987 | ECM, Inc. (ECM) | Overstaked Cortez JV placer claims with lode claims in Pipeline South area; leased claims to Royal Gold Inc. (Royal Gold) |
Royal Gold/Cortez JV | Formed the Royal/Cortez Joint Venture to resolve claim conflict |
Gold Fields | Commences gold production from Chimney Creek. |
Santa Fe | Discovers Rabbit Creek gold deposit. |
1987–1988 | American Barrick | Betze, Screamer, Deep Star, Rodeo, Meikle (previously named Purple Vein), South Meikle, and Griffin deposits/zones discovered |
1987–1995 | First Miss Gold Inc. (First Miss) | Subsidiary of First Mississippi Corporation created to conduct mining operations at Getchell. Open pit mining began in 1989. Getchell Main underground deposit identified in 1993, with production beginning in 1995. Turquoise Ridge Underground deposit discovered in 1993. |
1987–1989 | Royal Gold | Conducted geophysical surveys and drilling programs, identifying low-grade gold mineralization |
1988 | Newmont | Commissioned Mill 3 at Rain and Mill 5 (now referred to as the Gold Quarry concentrator) at Gold Quarry |
1989 | Newmont | Commissioned Mill 4 in the North Area |
Santa Fe | Commences gold production from Rabbit Creek. |
1990 | American Barrick | Autoclave operations begin at Goldstrike |
Royal Gold | Addition of roasting circuit to Cortez Mill No. 1 |
1991 | Cortez JV | Royal/Cortez Joint Venture terminated. Cortez JV leased Pipeline South area directly from ECM Discovered Pipeline and Gap deposits |
Hanson Natural Resources Company (Hanson) | Acquires Gold Fields. |
1993 | Santa Fe | Acquires Chimney Creek operations following an asset exchange with Hanson. Consolidates Rabbit Creek and Chimney Creek into the Twin Creeks operations |
1994 | Newmont | Commissioned Mill 6 (now Gold Quarry) roaster at Gold Quarry |
1994–1999 | Pittston Nevada Gold Corporation (Pittston) | Geochemical sampling and RC drilling on west side of Pequop Mountains identified gold anomalies in the Long Canyon area. |
1996 | Cortez JV | Construction of Cortez Mill No. 2 Used geochemical and geophysical surveys to guide deep reverse circulation (RC) drilling, initially focusing on an area immediately west of the Cortez Fault |
| | | | | | | | |
Date: February, 2022 | | Page 5-2 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
| | | | | | | | |
Year | Operator | Comment |
1996–1998 | Getchell Gold Corporation (Getchell Gold) | First Miss changes name to Getchell Gold. Construction started on Turquoise Ridge Underground mine. |
1997 | Newmont | Acquires Santa Fe. Open pit portion of the Rabbit Creek deposit renamed to the Mega pit. Open pit portion of the Chimney Creek deposit renamed to the Vista pit. Pinon mill associated with the Mega pit, treating oxide ore. Sage and Juniper mills associated with Vista pit treating refractory and oxide ore, respectively. |
1998 | Placer Dome Inc. (Placer Dome) | Announces merger with Getchell Gold. Suspends Turquoise Ridge Underground operations in 1999, and closes entire property in 2002. Operations restart at Turquoise Ridge Underground in 2003. |
Cortez JV | Discovered Crossroads and Pediment deposits |
1999 | American Barrick/Newmont | Asset exchange to rationalize the ownership and control of both the surface and subsurface estates that were jointly owned by the parties and to reduce the number of complex agreements that were needed to permit efficient operation and development of properties owned by both companies |
Cortez JV | Cortez Mill No. 1 placed on care and maintenance |
2000 | American Barrick | Roaster operations begin at Goldstrike |
2001 | Newmont | Merged with Battle Mountain |
2002 | Cortez JV | Discovered Cortez Hills deposit |
2003 | Placer Dome/Newmont | Form the Turquoise Ridge Joint Venture, 75% Placer Dome interest, 25% Newmont interest. |
2004 | Cortez JV | Discovered Cortez Hills Lower Zone |
2005 | Pittston | Sold Long Canyon area land package to AuEx |
2006 | Barrick | Acquired Placer Dome, obtained 60% interest in Cortez JV; obtained interest in Turquoise Ridge Joint Venture |
2006 | Newmont | Commenced mining at Copper Canyon; renamed to Phoenix |
2007 | NewWest Gold | Joint venture with AuEx. |
2007–2011 | Fronteer Gold | Acquired NewWest Gold. Completes major drill program |
2009–2018 | Barrick | Closes Getchell underground mine. Evaluation drilling of Vista underground area. North Portal developed 2011. South Portal developed 2013, after which Vista underground put on care and maintenance. Mining recommenced at Vista underground in 2018. |
2011 | Barrick | Discovered Goldrush deposit |
Newmont | Acquired Fronteer Gold |
2016 | Newmont | Commenced mining at Long Canyon |
2019 | Barrick/Newmont | Established NGM JV |
2021 | NGM | Completed updated feasibility study on the Goldrush deposit |
| | | | | | | | |
Date: February, 2022 | | Page 5-3 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
6.0 GEOLOGICAL SETTING, MINERALIZATION, AND DEPOSIT
6.1 Deposit Type
The deposits that comprise the Nevada Operations are considered to be examples of Carlin-style carbonate-hosted disseminated gold–silver deposits and intrusion-related gold–copper–silver skarn deposits.
Host rocks for Carlin-style deposits are most commonly thinly-bedded silty or argillaceous carbonaceous limestone or dolomite, commonly with carbonaceous shale. Although less mineralized, non-carbonate siliciclastic and rare metavolcanic rocks can locally host gold that reaches economic grades. Felsic plutons and dikes may also be mineralized at some deposits. Deposits typically have a tabular shape, are stratabound, localized at contacts between contrasting lithologies, but can also be discordant or breccia-related. Mineralization consists primarily of micrometer-sized gold and sulfide grains disseminated in zones of siliciclastic and decarbonated calcareous rocks and are commonly associated with jasperoids. Major ore minerals include native gold, pyrite, arsenopyrite, stibnite, realgar, orpiment, cinnabar, fluorite, barite, and rare thallium minerals. Gangue minerals typically comprise fine-grained quartz, barite, clay minerals, carbonaceous matter, and late-stage calcite veins.
Host rocks for intrusion-related gold–copper–silver skarn deposits include sedimentary carbonates, calcareous clastic rocks, volcaniclastic rocks or (rarely) volcanic flows. They are commonly related to high to intermediate-level stocks, sills, and dykes of gabbro, diorite, quartz diorite, or granodiorite composition. Mineralization frequently displays strong stratigraphic and structural controls. Deposits can form along sill–dike intersections, sill–fault contacts, bedding–fault intersections, fold axes, and permeable faults or tension zones. Pyroxene-rich Au skarns typically contain a sulfide mineral assemblage comprising native gold ± pyrrhotite ± arsenopyrite ± chalcopyrite ± tellurides ± bismuthinite ± cobaltite ± native bismuth ± pyrite ± sphalerite ± maldonite. Garnet-rich Au skarns can contain native gold ± chalcopyrite ± pyrite ± arsenopyrite ± sphalerite ± magnetite ± hematite ± pyrrhotite ± galena ± tellurides ± bismuthinite.
6.2 Regional Geology
The geology of northern Nevada displays a complicated sequence of orogeny and tectonism, summarized from oldest to youngest (Stewart (1980) and Jory (2002)) in Table 6-1. A summary map showing the key regional features is included as Figure 6-1.
Figure 3-2 to Figure 3-6 included summary property geology maps for each of the major mining complexes.
6.2.1 Carlin Complex
Gold deposits within or adjacent to the Carlin Complex are hosted by lower Paleozoic sedimentary rocks that are subdivided into three major packages, as summarized in Table 6-2.
| | | | | | | | |
Date: February, 2022 | | Page 6-1 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 6-1: Regional Geology Plan
Note: Figure provided by NGM, 2021. Black outline is the outline of the AOI.
| | | | | | | | |
Date: February, 2022 | | Page 6-2 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 6-1: Regional Geology
| | | | | |
Age | Comment |
Miocene | 14–20 Ma basin-and-range extension occurred with north–south faulting, deposition of volcaniclastic and sedimentary rocks in basins, and exposure of lower Paleozoic rocks. |
Eocene | Extension and magmatism. Emplacement during the Tertiary of felsic to intermediate dikes and associated small epizonal intrusions; some associated volcanism |
Late Jurassic | Late/post-Elko Orogeny plutonism, stocks/dikes emplaced, and contact metamorphism |
Mesozoic | Late Paleozoic tectonism during Early to Middle Pennsylvanian time (Humboldt Orogeny) followed by deposition of shelf carbonate sequences during the Middle Mississippian to Early Pennsylvanian. A third period of resumed uplift and folding, possibly related to the Early Triassic Sonoma Orogeny, was followed by the Early Cretaceous Sevier Orogeny, a period of eastward-directed folding and thrusting. These uplifts were accommodated by the development of north–northwest-striking faults and associated north–northwest-trending upright folds |
Late Devonian to Early Mississippian | Compressional tectonism associated with the Late Devonian to Middle Mississippian Antler Orogeny resulted in regional-scale folding and east-directed imbricate thrusting of the westernmost siliciclastic package over the eastern carbonate package along the Roberts Mountains Thrust. The accreted mass formed the Antler highlands. Erosion of the highlands during the Middle Mississippian to Early Pennsylvanian shed an easterly-directed overlap assemblage of clastic rocks |
Lower Paleozoic | From the Cambrian to Early Mississippian, the northern portion of Nevada was situated along a stable paleo-continental margin. A westward-thickening, prism-shaped sedimentary package was deposited from the outer margins of the paleo-continental shelf into an adjacent oceanic basin. The western sedimentary package predominantly consisted of siliciclastic rocks whereas the eastern portion of the sedimentary package consisted primarily of silty carbonate rocks |
| | | | | | | | |
Date: February, 2022 | | Page 6-3 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 6-2: Lithological Setting, Carlin Complex
| | | | | | | | | | | | | | |
Assemblage | Formation | Description | Notes | Example Deposits |
Eastern | Roberts Mountains Formation | Silty, fossiliferous, and laminated limestones; sedimentary breccias | Fossiliferous debris flows and 3–15 cm (1–6 inch) thick calcarenite beds are common in the uppermost 120 m (400 ft) Lower 240 m (800 ft) of planar laminated silty limestone grading upward into wavy (“wispy”) laminated silty limestone with abundant bioclastic debris | Carlin, Betze, West Leeville, Pete, Screamer, Deep Post, Goldbug–Post, and Mike |
Popovich Formation | Limestones, limey mudstones and sedimentary breccias | Informally named Bootstrap limestone is as much as 390 m (1,300 ft) thick at the north end of the Carlin trend. Fossiliferous debris flows occur proximal to the Bootstrap limestone | Betze–Post, Genesis–Blue Star, Gold Quarry (Deep West), Meikle, Goldbug–Rodeo, Deep Star, Bootstrap-Capstone, and Dee-Storm |
Rodeo Creek Formation | Siltstones and argillites; containing basal and internal sandstone horizons | Upper portion may be removed by Roberts Mountains thrust Flat-lying, 73–91 m (250–300 ft) thick silty to sandy facies informally named the Bazza Sands or Sandstone in the Goldstrike area Basal calcarenite thins northward, and is mostly absent north of Betze-Post area | Portions of Leeville and Goldstrike underground (Upper Rodeo) |
Western | Vinini Formation | Siltstones, mudstones, and cherts | | Capstone, Big Six, Crow, and Antimony Hill |
Slaven Formation | Siltstones, mudstones, and cherts |
Elder Formation | Siltstones, mudstones, and cherts |
Overlap | Chainman Formation | Sandstone and conglomerate | | |
Pilot Formation | Mudstones | Rain, Emigrant |
Guilmette Formation | Limestones; micritic and stomatoporoid-bearing |
Strata on the Carlin trend record at least three styles and orientations of contractional structures which form a consistent regional-scale deformation sequence (Rhys et al., 2015). Phase 1 deformation is associated with the Roberts Mountains thrust. Phase 2 deformation comprises development of north to northeast-trending, east-vergent folds, and Phase 3 deformation consists of northwest-trending, upright folds and reverse faults.
| | | | | | | | |
Date: February, 2022 | | Page 6-4 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Replacement and breccia mineralization styles may be associated with decalcification and clay alteration, dissolution breccias, silicification, development of silicified or jasperoidal breccias, cataclastic breccias and disseminated replacement in Jurassic dikes. The alteration styles can occur together, can zone outwards from faults, and can occur singly, preferentially affecting stratigraphic horizons lateral to faults.
Pervasiveness and intensity of alteration varies both within and between gold deposits, depending on magnitude of the mineralizing system, nature of the host rock, and structural preparation.
Carlin Trend-style mineralization consists primarily of micrometer-sized gold and sulfides disseminated in zones of siliciclastic and decarbonated calcareous rocks and commonly associated with jasperoids. Mineralization is predominantly in the form of oxides, sulfides, or sulfide minerals in carbonaceous rocks, and the ore type determines how and where it is processed.
6.2.2 Cortez Complex
The principal lithologies of the Cortez Complex are summarized in Table 6-3.
Most of the largest gold deposits within the Cortez Complex lie within approximately 300 ft of the Roberts Mountain Thrust at the base of the allochthonous upper plate. The stratigraphy is cut by a series of north–northwest, northwest, northeast, and north–northeast-striking high- and low-angle faults with extensive fracturing, brecciation, and folding. These faults both control and displace mineralization, with evidence for both dip-slip and oblique-slip displacements.
The alteration style at Cortez is similar to that described for the Carlin Complex.
Weathering has affected those deposits that are exposed on surface, resulting in oxide ores, which overlie the refractory sulfides. Weathering extends to about 60 m depth at Cortez.
Mineralization consists primarily of submicrometer- to micrometer-sized gold particles, very fine sulfide grains, and gold in solid solution in pyrite. Gold mineralization occurs disseminated throughout the host rock matrix in zones of silicified and decarbonatized, argillized, silty calcareous rocks, and associated jasperoids. Gold may occur around limonite pseudomorphs of pyrite and arsenopyrite.
6.2.3 Long Canyon Complex
The major lithologies of the Long Canyon Complex are summarized in Table 6-4.
Three sets of faults have been identified. The earliest structures are northwest-vergent reverse faults. Two generations of normal faults are present, the earlier normal fault set trends roughly north–south to 020°, while the later set of normal faults has a moderate to steep dip, both to the east and west, and strike between due north and 040°. The third fault set consists of subvertical, northwest striking strike-slip faults.
| | | | | | | | |
Date: February, 2022 | | Page 6-5 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 6-3: Lithological Setting, Cortez Complex
| | | | | | | | | | | |
Assemblage | Formation | Age | Description |
Eastern (autochthonous lower plate) | Horse Canyon Formation (Rodeo Creek Formation equivalent) | Devonian | Siltstone, mudstone, chert and argillite |
Wenban Formation | Early Devonian | Limestone |
Roberts Mountains Formation | Silurian-Devonian | Silty, fossiliferous, and laminated limestones; sedimentary breccias |
Hanson Creek Formation | Ordovician | Dolomite and silty limestone |
Eureka Formation | Ordovician | Quartzite |
Hamburg Dolomite | Cambrian | Limestones and dolomites |
Western (allochthonous upper plate) | Slaven Formation | Devonian | Chert with occasional thin interbeds of carbonaceous shale and limestone |
Fourmile Canyon Formation | Silurian | Chert, siltstone, argillite, and shale with a few thin beds of sandstone |
Elder Formation | Silurian | Feldspathic silty sandstone, with interbeds of siltstone, tuffaceous shale, and thin chert |
Valmy Formation | Ordovician | Massive quartzite and sandstone interbedded with chert, shale, siltstone, greenstone, and minor limestone |
Vinini Formation | Ordovician | Bedded chert and interbedded quartzite and shale, alternating carbonaceous shale and quartz siltstone, and irregularly interbedded shale, siltstone, sandstone, and limestone, and tholeiitic volcanic rocks |
Intrusive | Dikes | Pliocene–Pleistocene | Rhyolite |
Dikes | Pliocene | Andesite |
Dikes | Oligocene | Biotite–quartz–sanidine porphyry |
Porphyry | Eocene | |
Dikes and sills | Tertiary | Dacite and rhyodacite |
Dikes | Jurassic–Cretaceous | Felsic and mafic intrusions |
Gold Acres Stock | Jurassic–Cretaceous | |
Granodiorite | | |
Mill Canyon Stock | Jurassic | Biotite–quartz monzonite |
Extrusive/Volcaniclastic | Flows | Pliocene–Pleistocene | Rhyolite |
Flows | Pliocene | Andesite |
Caetano Tuff | Oligocene | Water laid rhyolitic tuffs, together with lesser amounts of andesitic tuff, sandstone and conglomerate |
| | | | | | | | |
Date: February, 2022 | | Page 6-6 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 6-4: Lithological Setting, Long Canyon Complex
| | | | | | | | | | | |
Age | Unit | Subunit | Note |
Quaternary | Alluvium | | Mixed lithology gravels |
Mesozoic | Lamprophyre | | Intrusive dikes and sills |
Ordovician | Pogonip Group | LC0 | Strongly lenticular laminated limestone. |
LC1 | Non-laminated or indistinctly-laminated limestone |
LC2 | Well-laminated limestone |
LC3 | Mottled, stylolitic limestone, or locally dolomitized limestone, is typical and may display local wavy lamination |
Cambrian | Notch Peak Formation | LC4 | Typically dolomite, non-laminated, and commonly contains abundant Nuia (fossil algae) |
LC5 | Upper portion has a distinctive zebra dolomite texture; lower portion is oolitic. |
LC6 | Limestone, locally can be hydrothermally dolomitized |
LC7 | Stylolitic limestone with coarse-grained fossiliferous intervals |
Typical alteration assemblages include decalcification, argillization, oxidation, hydrothermal dolomitization and local silicification.
Gold mineralization is concentrated in Notch Peak and Pogonip limestone at the margins of the Notch Peak dolomite. Mineralization is both stratigraphically and structurally controlled. Mineralization occurs most commonly at the upper and lower margins of the dolomite, but primarily within the limestone units.
Gold occurs primarily in zones of polyphase dissolution breccias that are localized in minor faults and fold hinges in the structurally-complex areas along and adjacent to dolomite block margins. Two general phases of brecciation are present, including calcareous breccias and later, Fe ± As oxide-rich breccias, which carry the highest gold grades. Breccias are accompanied by variable pervasive silicification.
Mineralization consists primarily of sub-micrometer-sized gold particles along the margins of oxidized pyrite grains. Some gold grains were observed encapsulated in silica. Gold was also detected by scanning electron microscopy within an arsenical rim on one pyrite grain.
6.2.4 Phoenix Complex
The main geological units of the Phoenix Complex area are provided in Table 6-5.
| | | | | | | | |
Date: February, 2022 | | Page 6-7 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 6-5: Lithological Setting, Phoenix Complex
| | | | | | | | |
Age | Unit | Note |
Cenozoic | Volcanic rocks and alluvium | Includes 3 Ma Pliocene olivine basalt flows and Quaternary–Tertiary alluvium |
Tertiary | Tuff | 33 Ma Caetano welded siliceous tuff |
Cretaceous | Granodiorite porphyry | 38 Ma Copper Canyon stock |
Mississippian, Pennsylvanian and Permian | Havallah sequence (formerly Pumpernickel Formation) | Radiolarian ribbon chert, and argillite associated with variable, but generally subordinate, siliciclastic, calc-arenitic, and volcaniclastic turbidites and slump deposits |
Pennsylvanian and Permian | Edna Mountain Formation | Chert–pebble conglomerate and calcareous sandstone and siltstone |
Antler Peak Limestone | Limestone unit, now recrystallized and metasomatized to marble or skarn |
Battle Formation | interbedded calcareous to siliceous conglomerate and sandstone with lesser calcareous siltstone and shale |
Upper Devonian to Mississippian | Scott Canyon Formation | Bedded chert, marine siliciclastic sedimentary rocks, and massive to pillowed metabasalt with minor limestone and carbonaceous black chert |
Cambrian | Harmony Formation | Poorly-sorted feldspathic and micaceous sandstone, with lesser limestone and shale, which accumulated in a submarine fan setting |
Two major regional scale north–south-striking faults demark the Phoenix mineralization corridor. The west boundary is the Copper Canyon fault zone (also known as the Canyon fault) and to the east, is the Virgin fault zone. Numerous subsidiary faults are developed in the vicinity of these main faults.
Hydrothermal alteration in the Project is centered on the Copper Canyon stock, which has produced about 4,200 acres of hornfels and skarn. Skarn alteration is hosted by all sedimentary rock units adjacent to the Copper Canyon granodiorite, with the reactive calcareous protoliths of the Edna Mountain Formation, Antler Peak Limestone and Battle Formation hosting the bulk of the skarn alteration. Alteration of the Copper Canyon stock consists of quartz–sericite–pyrite argillic, or propylitic, alteration.
Preferred host lithologies for gold mineralization are the Antler Peak Limestone and Battle Formation. Copper mineralization hosts include the Copper Canyon stock and Havallah sequence.
Gold mineralization occurs freely at gangue–gangue or at sulfide–gangue grain boundaries, and only rarely as inclusions within gangue minerals. Some inclusions were noted in quartz, pyroxene, epidote, and orthoclase. The remaining gold occurred as inclusions totally encapsulated by sulfide minerals including pyrite, pyrrhotite, and to a lesser extent arsenopyrite, chalcopyrite, and sphalerite. Silver minerals are dominantly electrum, hessite, and lesser argentite.
Copper oxide mineralization locally contains minor amounts chalcanthite, malachite, chrysocolla, azurite, and lesser cuprite. Enriched copper mineralization typically has chalcopyrite ± covellite present. Covellite locally rims chalcocite grains where the effects of oxidation are more advanced. In hypogene mineralization, chalcopyrite occurs as
| | | | | | | | |
Date: February, 2022 | | Page 6-8 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
disseminations and bedded replacements with skarn and silicate minerals, and in conjunction with pyrite.
6.2.5 Turquoise Ridge Complex
The key lithologies of the Turquoise Ridge Complex are summarized in Table 6-6.
The Getchell Fault is a major north–south striking fault, and is a master fault to a number of steeply-dipping, north-striking faults to the east of, and antithetic to it. A series of high-angle normal faults strike northeast and dip steeply northwest in the Turquoise Ridge deposit area.
Contact metamorphic alteration is associated with the Osgood stock, forming skarns in carbonate-rich lithologies. Alteration not associated with the granodiorite consists of decalcification, argillization, silicification, and development of jasperoid bodies. Overprinting clay alteration is related to weathering processes.
Preferred host lithologies for gold mineralization are the Comus and Prebble Formations, followed by the Valmy and Etchart Formation
Sub-microscopic gold mineralization is associated with pyrite, arsenopyrite, quartz, calcite, realgar and orpiment. Gold-bearing zones can be located close to granodiorite dikes and beneath basaltic intrusions.
6.3 Property Geology
6.3.1 Carlin Complex
Carlin Complex deposits include the following zones or area:
•South Arturo: South Arturo open pit, El Niño underground. Deposit length is about 1,970 ft, the deposit width is approximately 394 ft wide, and averages about 50 ft in thickness;
•Betze–Post: Deep Post, Post, Betze, North Betze, West Betze, Screamer North Screamer, and West Barrel. Deposit lengths range from 2,000–5,300 ft, deposit widths are 1,000–4,500 ft, and deposit thicknesses range from 80–250 ft;
•Meikle–Rodeo: East Banshee, West Banshee, Meikle, South Meikle, East Griffin, Extension, West Griffin, Rodeo, Barrel, West Rodeo, and North Post. Deposit lengths range from 1,500–3,100 ft, deposit widths are 200–2,300 ft, and deposit thicknesses range from 250–1,400 ft;
•North Carlin: Tri-Star/Genesis (Silverstar, Bobstar, Goldstar, and Payraise), Perry, Lantern/Green Lantern, Exodus. Deposit lengths range from 900–10,000 ft, deposit widths are 550–6,000 ft, and deposit thicknesses range from 30–550 ft;
•Carlin–Gold Quarry: Quarry Main, Deep West, Deep Sulfide Feeder, Chukar North, Chukar South, and Carlin. The Good Hope, Mac, Magpie, Southwest, Wedge areas do not have estimated mineral resources or mineral reserves. Deposit lengths range from 4,500–12,000 ft, deposit widths are 950–8500 ft, and deposit thicknesses range from 100–2000 ft;
•Leeville: West Leeville, Turf, and Four Corners. Deposit lengths range from 2,000–4,600 ft, deposit widths are 300–5,200 ft, and deposit thicknesses range from 30–300 ft;
| | | | | | | | |
Date: February, 2022 | | Page 6-9 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 6-6: Lithological Setting, Turquoise Ridge Complex
| | | | | | | | |
Age | Unit/Lithology | Comment |
Quaternary and Tertiary | | Alluvials, gravels and minor tuff in low-lying fault-bounded graben areas. |
Tertiary | | Basaltic and andesitic lavas and poorly-exposed silicic tuff. Age date of c. 22 Ma. |
Cretaceous | Osgood Mountains pluton | Medium-grained equigranular to porphyritic granodiorite stock and related dikes and sills of dacite porphyry. |
| c. 114 Ma dacite dikes |
Mississippian-Permian | Havallah Formation | Siliciclastic and basaltic rocks |
Pennsylvanian-Permian | Etchart Formation | Variably sandy/silty limestone, calcareous siltstone/sandstone and conglomerate. |
Mid-Pennsylvanian (?) | Battle Formation | Gray quartzite cobble conglomerate, with a gray sandy matrix. |
Ordovician | Valmy Formation | Pillow basalt flows with subordinate amounts of hyaloclastite, chert and argillite. |
Cambrian–Ordovician (?) | Comus Formation | Black shale, siltstone, and silty to fine-grained carbonate rocks. Basalt flows and ash to lapilli tuff and debris flows of basaltic composition. Abundant mafic and ultramafic alkalic sills intrude the laminated and thin-bedded sedimentary rocks. |
Cambrian | Preble Formation | Black to gray, laminated silty mudstone, locally phyllitic. Siltstone, and shale with subordinate carbonate lenses. |
Cambrian | Osgood Mountain Formation | Quartz arenite, quartzite |
•South Carlin: Pete Bajo, Fence, Full House. Deposit lengths range from 2,000–4,000 ft, deposit widths are 500–900 ft, and deposit thicknesses range from 10 to 60 ft;
•Emigrant: Emigrant. The deposit is 12,000 ft long, 3,300 ft wide, and has a thickness range from 10–330 ft.
Example cross-sections of deposits in the Carlin Complex are included as Figure 6-2 to Figure 6-6. A cross-section through the Meikle–Rodeo deposit is provided in Figure 6-7.
Geological, structural, alteration and mineralization descriptions were included in Chapter 6.3.1.
6.3.2 Cortez Complex
Cortez Complex deposits include the following deposits:
•Cortez NW Deep and Cortez Hills open pit and underground: combined deposit lengths are 6,800 ft, 4,000 ft wide, and deposit thicknesses range from 10–350 ft;
•Crossroads and Pipeline: deposit length is 11,000 ft, 3,400 ft wide, and deposit thicknesses range from 50–1,400 ft;
| | | | | | | | |
Date: February, 2022 | | Page 6-10 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 6-2: Geological Cross-Section, Goldstrike Area
Note: Deposits shown in Goldstrike open pit area.
| | | | | | | | |
Date: February, 2022 | | Page 6-11 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 6-3: Geological Cross-Section, Gold Quarry Area
| | | | | | | | |
Date: February, 2022 | | Page 6-12 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 6-4: Geological Cross-Section, Exodus–Leeville Area
Note: Deposits shown are Exodus (left) and Leeville (right)
| | | | | | | | |
Date: February, 2022 | | Page 6-13 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 6-5: Geological Cross-Section, Carlin–Pete Bajo Area
Note: Deposits shown are Carlin (left) and Pete Bajo (right)
| | | | | | | | |
Date: February, 2022 | | Page 6-14 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 6-6: Geological Cross-Section, South Arturo Area
Note: Figure prepared by NGM, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 6-15 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 6-7: Cross-Section, Meikle–Rodeo Deposit
Note: Figure prepared by Barrick, 2017.
| | | | | | | | |
Date: February, 2022 | | Page 6-16 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
•Gold Acres: deposit length is 7,000 ft, 2,600 ft wide, and deposit thicknesses range from 25–600 ft;
•Goldrush: deposit length is 17,300 ft, 1,400 ft wide, and deposit thicknesses range from 10–350 ft;
•Robertson: combined deposit lengths are 7,500 ft, 3,000 ft wide, and deposit thicknesses range from 150–1,400 ft.
Example cross- or long-sections of deposits in the Cortez Complex are included for Pipeline (Figure 6-8), Gold Acres (Figure 6-9), Goldrush (Figure 6-10), Robertson (Figure 6-11).
Geological, structural, alteration and mineralization descriptions were included in Chapter 6.3.2.
6.3.3 Long Canyon Complex
The Long Canyon complex consists of the Long Canyon deposit, which has a 13,000 ft strike length, is about 2,500 ft. wide, with mineralized zones varying in thickness from 20–250 ft.
An example geological section is provided in Figure 6-12.
Geological, structural, alteration and mineralization descriptions were included in Chapter 6.3.3.
6.3.4 Phoenix Complex
Phoenix Complex deposits include the following deposits:
•Fortitude, Bonanza and Greater Phoenix: combined deposit lengths are 16,000 ft long, 3,900 ft wide, and the deposits have a thickness range from 20–550 ft.
An example geological section is provided in Figure 6-13.
Geological, structural, alteration and mineralization descriptions were included in Chapter 6.3.4.
| | | | | | | | |
Date: February, 2022 | | Page 6-17 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 6-8: Cross-Section Pipeline
Figure 6-9: Cross-Section Gold Acres
| | | | | | | | |
Date: February, 2022 | | Page 6-18 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 6-10: Long-Section Goldrush
| | | | | | | | |
Date: February, 2022 | | Page 6-19 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
| | | | | | | | |
Date: February, 2022 | | Page 6-20 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 6-11: Cross-Section Robertson
Figure 6-12: Cross-Section, Long Canyon Deposit
| | | | | | | | |
Date: February, 2022 | | Page 6-21 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 6-13: Cross-Section, Phoenix Deposit
| | | | | | | | |
Date: February, 2022 | | Page 6-22 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
6.3.5 Turquoise Ridge Complex
Turquoise Ridge Complex deposits include the following deposits:
•Turquoise Ridge Surface (Mega, Vista), Turquoise Ridge Underground (North and South), Vista Underground: deposit lengths range from 2,600–4,593 ft, deposit widths range from 984–2,600 ft, and deposit thicknesses range from 10 ft–98 ft.
An example geological section is provided for the Turquoise Ridge Underground in Figure 6-14 and for Vista underground in Figure 6-15.
Geological, structural, alteration and mineralization descriptions were included in Chapter 6.3.5.
| | | | | | | | |
Date: February, 2022 | | Page 6-23 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 6-14: Cross-Section, Turquoise Ridge Underground Deposit
| | | | | | | | |
Date: February, 2022 | | Page 6-24 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 6-15: Cross-Section and Plan, Vista Underground Deposit
Note: Figure prepared by NGM, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 6-25 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
7.0 EXPLORATION
7.1 Exploration
7.1.1 Grids and Surveys
Prior to about 1985, surveys were completed by registered surveyors, using United States Geological Survey (USGS) base-stations, and optical instruments to survey collar locations and pit topography using angles and distances. Pre-mine topographic surveys were based on surface surveys, or alternatively, on airborne topographic surveys.
Current topographic surveys are completed on an as-needs basis. During operations, surveys may be completed daily; where no work is currently being undertaken, surveys may be years apart.
The datum used for each mine varies and could include mine grids, truncated State Plane NAD83 or NAD27, and truncated Universal Transverse Mercator. All sites have been translated to a NAD83 Zone 11 vertical datum 88 ft, which is used for regional programs.
7.1.2 Geological Mapping
Pre-mine geologic mapping was completed in eastern Nevada by geologists from the United States Geological Survey (USGS) and previous operators. From 1961 to date, surface-mapping was conducted at various scales, ranging from pit wall (1:1,200) to district (1:25,000) scales. Underground mapping is completed at scales ranging from 1:20 to 1:100.
7.1.3 Geochemistry
Geochemical samples were collected early in the Project history, and included stream sediment, soil, and rock chip samples. Owing to the long mining history within the AOI, geochemical sampling techniques used for grassroots exploration purposes have been typically superseded by data from drilling and open pit and underground mining. Current exploration typically does not use surface sampling methods, as the majority of the recent exploration successes are based on a combination of structural modelling and drilling to explore for mineralization at depth.
7.1.4 Geophysics
Geophysical methods have been used in Barrick, Newmont and NGM work programs within the AOI since 1973. From 1973–1993, geophysical tools were primarily regarded as support tools due to the initial discoveries cropping out on surface, or only having a thin veneer of cover, and the inability of the early methods to directly detect the deposits. Methods employed over the Project history included airborne and ground magnetics; radiometrics and electromagnetics (EM); gravity, resistivity, and controlled-source audio-frequency telluromagnetics (CSAMT) and magnetotellurics (MT); self-potential (SP); induced-polarization (IP); time domain pole-dipole IP; time domain MT/IP using a distributed assay system; electrical logging of drill holes; and downhole IP.
| | | | | | | | |
Date: February, 2022 | | Page 7-1 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Key uses of the geophysical survey data were to delineate intrusive rocks and thermal metamorphic halos, identify remnant-magnetized volcanic rocks and fault/structures, outline zones of pyrite at depth, and define zones of decalcification.
7.1.5 Petrology, Mineralogy, and Research Studies
Since 1961, a significant number of structural, petrology, mineralogy, lithogeochemical, and research studies have been completed on the gold and copper deposits within Northern Nevada, making the area one of the more intensively studied geologic provinces in the world. NGM maintains a database of such research as a reference tool for exploration purposes.
7.1.6 Qualified Person’s Interpretation of the Exploration Information
The exploration information was used to vector into potential mineralized zones. The exploration information has typically been superseded by the active mining operations.
7.1.7 Exploration Potential
Exploration potential exists adjacent to many of the deposits, along strike and at depth along favorable mineralized structures, and within favorable host lithologies.
7.2 Drilling
7.2.1 Overview
7.2.1.1 Drilling on Property
Across the entire AOI, drilling totals over 203,000 drill holes for >82 Mft of drilling.
Between 1905 and 1965–1966, drilling was completed primarily for early-stage, exploration-focused programs and for initial gold resource estimates. From 1966 onward, drilling was used to support advanced-stage project evaluation as well as deposit, pit, and underground delineation.
A drill summary table for the Project is provided in Table 7-1. Drill totals are broken out by complex in Table 7-2 to Table 7-6.
A drill collar location plan for the Project area is included in Figure 7-1. Drill collar locations for each mining complex are included as Figure 7-2 to Figure 7-7.
| | | | | | | | |
Date: February, 2022 | | Page 7-2 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 7-1: Drill Summary Table, Mining Complexes
| | | | | | | | |
Complex | Number of Drill Holes | Drilled Metreage (m) |
Carlin | 108,985 | 8,444,159 |
Cortez | 22,822 | 4,109,018.7 |
Long Canyon | 3,485 | 758,971 |
Phoenix | 7,591 | 853,541 |
Turquoise Ridge | 24,278 | 3,332,890 |
Total | 167,161 | 17,498,579.7 |
Note: Metreage has been rounded; totals may not sum due to rounding.
Table 7-2: Carlin Complex Drill Summary Table
| | | | | | | | | | | | | | |
Deposit/Area | Drill Type | Number of Drill Holes | Drilled Footage (ft) | Drilled Metreage (m) |
Betze–Post | Core | 2,747 | 1,551,289 | 472,833 |
Cubex | — | — | — |
RC | 19,976 | 4,713,271 | 1,436,605 |
Sub-total | 22,723 | 6,264,560 | 1,909,438 |
Meikle–Rodeo | Core | 6,006 | 2,709,801 | 825,947 |
Mud-rotary | 29 | 23,844 | 7,268 |
RC | 32,915 | 7,013,156 | 2,137,610 |
Sub-total | 38,950 | 9,746,802 | 460.2 |
Tristar | Air-rotary | 1,697 | 462,514 | 140,974 |
Core | 965 | 595,179 | 181,411 |
Mud-rotary | 35 | 50,079 | 15,264 |
RC | 3,527 | 1,951,985 | 594,965 |
Sub-total | 6,224 | 3,059,757 | 932,614 |
Perry | Core | 5 | 1,776 | 541 |
RC | 244 | 100,595 | 30,661 |
Sub-total | 249 | 102,371 | 31,203 |
Green Lantern | Air-rotary | 238 | 76,454 | 23,303 |
Core | 451 | 355,762 | 108,436 |
Mud-rotary | 20 | 39,003 | 11,888 |
RC | 1,248 | 772,498 | 235,457 |
Sub-total | 1,957 | 1,243,717 | 379,085 |
Exodus/Northwest Exodus | Underground RC | 607 | 111,660 | 36,168 |
Underground core | 847 | 696,159 | 212,189 |
Surface RC and core | 830 | 634,742 | 193,469 |
Sub-total | 2,284 | 1,449,561 | 441,826 |
Gold Quarry | Air-rotary | 1,412 | 654,604 | 199,523 |
Core | 1,889 | 1,069,366 | 325,943 |
Cubex | 1,665 | 151,317 | 46,121 |
Mud-rotary | 221 | 260,775 | 79,484 |
RC | 4,445 | 2,918,072 | 889,428 |
Sub-total | 9,632 | 5,054,134 | 1,540,499 |
| | | | | | | | |
Date: February, 2022 | | Page 7-3 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
| | | | | | | | | | | | | | |
Deposit/Area | Drill Type | Number of Drill Holes | Drilled Footage (ft) | Drilled Metreage (m) |
Leeville * | Underground conventional | 1,724 | 110,477 | 33,682 |
Underground RC | 9,121 | 1,270,049 | 387,210 |
Underground core | 4,396 | 1,906,229 | 586,532 |
Surface RC and core | 317 | 735,956 | 224,377 |
Sub-total | 15,558 | 4,022,711 | 1,231,801 |
Pete Bajo | Underground conventional | 1,252 | 44,536 | 13,575 |
Underground RC | 4,123 | 509,294 | 155,238 |
Underground core | 2,320 | 1,167,553 | 355,882 |
Surface RC and core | 1,411 | 702,565 | 214,142 |
Sub-total | 9,106 | 2,423,949 | 738,843 |
South Arturo UG | Underground RC | 166 | 32,735 | 9,978 |
Underground core | 53 | 19,003 | 5,792 |
Surface RC | 303 | 261,712 | 79,770 |
Surface Core | 116 | 63,692 | 19,416 |
Subtotal | 638 | 377,141 | 114,953 |
South Arturo OP* | Underground RC | 772 | 107,609 | 32,799 |
Underground Core | 375 | 134,350 | 40,950 |
Surface RC | 1,548 | 1,041,650 | 317,495 |
Surface Core | 306 | 385,679 | 116,945 |
Rotary | 536 | 219,737 | 66,976 |
Subtotal | 3,537 | 1,887,024 | 575,165 |
Emigrant | Air-rotary | 71 | 29,855 | 9,100 |
Core | 41 | 12,007 | 3,660 |
RC | 1,311 | 416,565 | 126,969 |
Sub-total | 1,425 | 458,427 | 139,728 |
Ren * | Underground RC and Core | 7,960 | 1,593,070 | 485,568 |
Surface RC and core | 769 | 1,335,691 | 407,119 |
Sub-total | 8,729 | 2,928,761 | 892,686 |
North Leeville | Underground conventional | — | — | — |
Underground RC | — | — | — |
Underground core | — | — | — |
Surface RC and core | 112 | 216,007 | 65,874 |
Sub-total | 112 | 216,007 | 65,874 |
Totals | | 108,985 | 37,430,407 | 8,444,159 |
Notes: Note: Metreage has been rounded; totals may not sum due to rounding. Leeville includes Rita K, Ren includes part of Meikle-Rodeo, South Arturo open pit includes part of South Arturo underground
| | | | | | | | |
Date: February, 2022 | | Page 7-4 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 7-3: Cortez Complex Drill Summary Table
| | | | | | | | | | | |
Drill Type | Number of Drill Holes | Drilled Feet (Mft) | Drilled Meters (Mm) |
Air rotary | 170 | 36,592 | 11,153.2 |
Core | 3,259 | 1,848,861 | 563,532.9 |
Mud rotary | 146 | 105,681 | 32,211.6 |
Reverse circulation and Cubex | 18,674 | 9,488,670 | 2,892,146.5 |
Other * | 3,029 | 2,001,229 | 609,974.5 |
Total | 22,822 | 13,481,032 | 4,109,018.7 |
Note: Metreage has been rounded; totals may not sum due to rounding.
Table 7-4: Long Canyon Complex
| | | | | | | | |
Drill Type | Number of Drill Holes | Drilled Meters |
Core | 2,096 | 558,509 |
RC | 1,373 | 193,960 |
RC pre collar/core tail | 16 | 6,501 |
Total | 3,485 | 758,971 |
Note: Metreage has been rounded; totals may not sum due to rounding.
Table 7-5: Phoenix Complex
| | | | | | | | |
Drill Type | Number of Drill Holes | Drilled Meters |
Core | 743 | 98,616 |
RC | 5,045 | 595,706 |
RC pre collar/core tail | 594 | 159,219 |
Unknown | 1,209 | 98,165 |
Total | 7,591 | 853,541 |
Note: Metreage has been rounded; totals may not sum due to rounding.
Table 7-6: Turquoise Ridge Complex
| | | | | | | | |
Drill Type | Number of Drill Holes | Drilled Meters |
Core | 8,610 | 1,412,297 |
RC and Cubex | 15,668 | 1,920,593 |
Total | 24,278 | 3,332,890 |
Note: Metreage has been rounded; totals may not sum due to rounding.
| | | | | | | | |
Date: February, 2022 | | Page 7-5 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 7-1: Drill Collar Location Plan, AOI
Note: Figure prepared by Newmont, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 7-6 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 7-2: Carlin Complex Drill Collar Location Plan, North Area
| | | | | | | | |
Date: February, 2022 | | Page 7-7 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 7-3: Carlin Complex Drill Collar Location Plan, South Area
| | | | | | | | |
Date: February, 2022 | | Page 7-8 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 7-4: Cortez Complex Drill Collar Location Plan
Note: Figure prepared by NGM, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 7-9 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 7-5: Long Canyon Complex Drill Collar Location Plan
Note: Figure prepared by NGM, 2021. Map north is to top of illustration.
| | | | | | | | |
Date: February, 2022 | | Page 7-10 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 7-6: Phoenix Complex Drill Collar Location Plan
Note: Figure prepared by NGM, 2021. Map north is to top of illustration.
| | | | | | | | |
Date: February, 2022 | | Page 7-11 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 7-7: Turquoise Ridge Complex Drill Collar Location Plan
Note: Figure prepared by NGM, 2021.
7.2.1.2 Drilling Supporting Mineral Resource Estimates
Any of the drill types noted in Chapter 7.2.2 can be used in estimation; however, the majority of the current estimates are supported by RC and core drilling.
7.2.1.3 Drilling Excluded For Estimation Purposes
Drill holes can be excluded from supporting estimates if there is sufficient uncertainty in location or orientation, or quality of assays. Where drill holes intersect the interpreted mineralization at significantly oblique angles, they may be excluded at the discretion of the modeler.
| | | | | | | | |
Date: February, 2022 | | Page 7-12 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
7.2.2 Drill Methods
Over the Project history, drilling included reverse circulation (RC), core, air rotary, mud rotary, and Cubex methods. Churn drilling was used in areas was completed in areas known to host placer gold. The majority of the areas where air rotary, mud rotary, Cubex and churn methods were used are mined out.
RC diameters were typically 5.5–6.5 in. Core sizes are typically HQ (2.5 in diameter) for surface drilling. Occasionally, surface core holes were reduced from HQ size to NQ (1.9 in) size if difficult drilling conditions were encountered. Surface metallurgical core included PQ (3.3 in), and SHR series (3.3 in; 4 in or 6 in) core.
7.2.3 Logging
Logging conducted depended on the operator of the complex at the time the information was collected, and the drill type. Typically, logging collected information such as lithology, stratigraphy, basic structural data, recovery, alteration, and mineralization. For mining operations, logging could also record metallurgical type, intensity codes for metallurgy and alteration, and geotechnical parameters such as rock quality designation (RQD) and number of fractures per foot, and comments by the geologist.
7.2.4 Recovery
Recoveries have been measured for the majority of the core holes. Procedures are in place to mitigate instances where core recovery becomes poor. Conversely, in areas of competent hard mineralization, core recoveries are at 95–100%.
7.2.5 Collar Surveys
During early operations, exploration and development drill programs, collar grid coordinates were determined by optical surveys, field estimates, Brunton compass and pacing, compass-and-string distance measurements, and for underground operations, measurements from surveyed control points, face, ribs and sill to triangulate each collar location.
Currently, the operations typically make use of laser survey or digital geographic positioning system (GPS) measurements to locate drill hole collars.
7.2.6 Down Hole Surveys
Determination of the hole trace was historically accomplished by projection of the initial collar orientation, using a downhole single-shot or multi-shot film camera (typical for most underground surveys), use of a downhole precession gyroscopic survey tool, or a gyroscopic tool requiring initial orientation with a compass.
Either north-seeking or conventional gyroscopic tools, or a combination, are used currently for down-hole survey purposes. Gyroscopic surveys are typically reported at 25 or 50 ft intervals.
| | | | | | | | |
Date: February, 2022 | | Page 7-13 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
7.2.7 Comment on Material Results and Interpretation
Drill spacing varies by complex, depending on deposit type and assumed or actual mining method:
•Carlin: approximately 6–21 m in the better drilled deposit areas to about 30–134+ m spacing on the less well drilled portions of the deposits;
•Cortez: approximately 9–15 m in the better drilled deposit areas to about 31–98+ m spacing on the less well drilled portions of the deposits;
•Long Canyon: approximately 8–11 m in the better drilled deposit areas to about 23–46+ m spacing on the less well drilled portions of the deposits;
•Phoenix: approximately 5–6 m in the better drilled deposit areas to 67+ m spacing on the less well drilled portions of the deposits;
•Turquoise Ridge: approximately 6–13 m in the better drilled deposit areas to about 30–91+ m spacing on the less well drilled portions of the deposits.
Drilling and surveying were conducted in accordance with industry standard practices at the time the information was collected, and provide suitable coverage of the zones of gold ± copper mineralization. Drilling methods provide reasonable core recovery. Logging procedures provide consistent descriptions.
These data are considered to be acceptable for mineral resource and mineral reserve estimation. There are no drilling or core recovery factors known to the QP that could materially impact the accuracy and reliability of the results.
7.3 Hydrogeology
Information obtained during early-stage hydrological and hydrogeological evaluations is superseded by data obtained from many years of mining activities.
In areas where new mining activity is planned in stand-alone projects, such as at Goldrush, additional hydrological and hydrogeological data collection is underway.
Dewatering is performed where required in the operations, using dewatering wells, or advanced development (normally with drain holes) which may later be used for mining purposes, drain holes drilled from existing excavations, or development headings and sumps.
7.3.1 Sampling Methods and Laboratory Determinations
Hydrogeology data, including pore pressure distribution and ground-water flow, were normally collected from geotechnical investigations in pre-construction studies and later from on-going programs in operating mines.
The primary method for collection of hydrology data is a large network of vibrating wire piezometers. These vibrating wire piezometers provide water level data. QA/QC is achieved by redundancy in network and annual audits of sensor parameters and performance.
Another source of data is hydrologic testing. Most wells that are drilled are subjected to extensive hydrologic testing to establish aquifer parameters. These tests are typically injection
| | | | | | | | |
Date: February, 2022 | | Page 7-14 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
(slug) tests, spinner tests, step test, packer tests, short-term pump tests and long-term pump tests. These tests are analyzed using classical hydrology methods. Most of the aquifers on site are in fractured bedrock and therefore, fracture-flow controlled, in-situ testing is relied upon more heavily than laboratory testing; however, in some of the alluvial aquifers additional logging/laboratory testing of sonic cores is done. The laboratory tests are completed to establish a detailed log (USGS Soil Classification), moisture content, Atterberg limit, grain size distribution, specific gravity and permeability (flex-wall permeability tests). Numeric models have been developed using parameters from above-mentioned methods and geological modelling.
7.3.2 Comment on Results
A combination of historical and current hydrological and hydrogeological data, together with mining experience, are used to prepare the mine designs, dewatering plans and monitoring for existing and planned operations.
7.3.3 Groundwater Models
Where hydrological conditions warranted, groundwater models were prepared using industry-standard water modelling software.
7.4 Geotechnical
Information obtained during early-stage geotechnical evaluations is superseded by data obtained during mining activities.
7.4.1 Sampling Methods and Laboratory Determinations
Geotechnical core logging and in-situ geotechnical mapping are the principal data collection methods. Geotechnical core logging is directly inputted into the digital logging database, acQuire. If surface access (e.g., open pit) or underground access (e.g., mine workings) is available, then the geotechnical core logging results may be confirmed or supplemented with in situ assessment of geotechnical domains using geotechnical mapping of active development and/or window or scanline mapping.
Typical data collected in logging and mapping programs include physical rock properties and joint wall conditions used to determine rock mass characterization. Data collected can include RQD, joint frequency, number of joint sets, joint roughness, joint alteration, joint in-filling, point load tests, rock mass fabric characterization and information on discrete structural features. Rock mass characterization systems employed can include rock tunnelling quality index (Q system), rock mass rating (RMR), mining rock mass rating (MRMR) and geological strength index (GSI).
Typical structural characterization consists of documenting joint sets (including bedding, foliation), faults, shear zones, and dikes through core intercepts, televiewer surveys or in situ mapping. Data collected can include observations such as dip, dip direction, spacing, thickness and persistence.
Laboratory testing samples are taken from diamond core during logging efforts and sent to independent rock testing laboratories for testing. Intact rock properties are characterized
| | | | | | | | |
Date: February, 2022 | | Page 7-15 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
through field and laboratory testing as required. Properties to be quantified can include Unconfined Compressive Strength (UCS), Young’s modulus, Poisson’s ratio, tensile tests and direct shear tests. Multiple samples are taken for each rock unit to account for any irregularities within the core specimens.
Field stress characterization is conducted using documented observations (disking and breakouts), documented back analysis, field measurements and regional stress models. Observation of disking in geological core logging is used to identify zones of stress differential within the rock mass. Stress differential is typically encountered where there is a mechanical contrast in material stiffness, typically between two geotechnical domains.
In active operations, data collection includes inspection of active headings on a basis stipulated by the individual mine site., and determinations if the support system installed is appropriate for the in-situ ground conditions.
Backfill is routinely tested to validate mix design and quality. Underground sites test backfill in on-site laboratories for unconfined compressive strength. External laboratories are utilized to conduct testing outside of the capacity of the site. These tests may include Young’s Modulus, Poisson’s ratio and tensile testing.
Ground support, used in the support of mine workings, is routinely tested to confirm quality of installed elements. Quality assurance and quality control (QA/QC) practices include pull testing of rock bolts to validate material and installation quality, and UCS testing of shotcrete/fibercrete to confirm batching and mix design.
A range of geotechnical monitoring systems are employed at the underground sites. These systems can include extensometers, either single-point or multi-point units, closure stations, load sensing instruments and sloughmeters. Microseismic arrays, consisting of both uniaxial and triaxial geophones, collect seismic data at mines where seismicity is identified as a geotechnical risk.
7.4.2 Comment on Results
A combination of historical and current geotechnical data, together with mining experience, are used to engineer ground support guidelines and procedures that all ground support designs must follow. These data and mining experience support the geotechnical operating considerations used in the mine plans in Chapter 13 of this Report.
| | | | | | | | |
Date: February, 2022 | | Page 7-16 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
8.0 SAMPLE PREPARATION, ANALYSES, AND SECURITY
8.1 Sampling Methods
Sampling is variable by mining complex and mineralization style.
Air-rotary and mud-rotary drill holes were sampled on 5–100 ft intervals. Cubex drilling was sampled on 5–10 ft intervals. RC drill holes were typically sampled on 5 ft intervals. Core samples were nominally taken at 5 ft intervals, but could vary to a minimum of 1 ft to respect lithological contacts.
8.2 Sample Security Methods
Sample collection from drill point to laboratory relied upon the fact that samples were either always attended to, or were stored in locked on-site preparation facility, or stored in a secure area prior to shipment to the external laboratory. Chain-of-custody procedures consisted of filling out sample submittal forms to be sent to the laboratory with sample shipments to ensure that all samples were received by the laboratory.
8.3 Density Determinations
The majority of the data were from measurements collected by exploration or mine site personnel using the water displacement method. These data were used to support mineral resource and mineral reserve estimates.
In some instances, verification of the site procedures was performed by external laboratories, using selected core pieces. Verification laboratories included, where known, Zonge Engineering in Tucson, AZ (Zonge); Elliot Geophysical Laboratories (Elliot); and AGRA Metallurgical Laboratory in Reno (AGRA).
8.4 Analytical and Test Laboratories
Given the long history of the Nevada Operations, there are numerous laboratories that were used over the Project history. These include, where known:
•Independent laboratories: ALS Chemex in Elko, Nevada, ALS Chemex in Winnemucca, ALS Chemex in Sparks, Nevada (ALS Reno) and Vancouver, Canada (ALS Vancouver); American Assay Laboratories in Sparks, Nevada (AAL Sparks); Analytical Services Laboratory; Barringer Laboratories in Reno, Nevada (now BSI Inspectorate); Bondar-Clegg Laboratory in Reno (now ALS Chemex); BSI Inspectorate Laboratory; Core Laboratory; Golden Giant Laboratory; GSI; Hazen Research Laboratories; Lakefield Metallurgical Consultants; Legend Laboratories; McClelland Laboratory; Monitor Hesperia, CA Laboratory; Monitor Geochemical Laboratory in Elko, Nevada; Rocky Mountain Geochemical Laboratory; SGS Mineral Services; Shasta Analytical; Skyline Laboratories in Tucson, Arizona; Treweek Laboratory; Universal Laboratory Inc.; Valmy Trend Arev Source; X-Ray Assay Laboratory Toronto, Canada;
•Non-independent laboratories: Cortez mine laboratory; Battle Mountain mine laboratory; Duval laboratory (became Battle Mountain); Lone Tree laboratory; Newmont Gold
| | | | | | | | |
Date: February, 2022 | | Page 8-1 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Laboratories; Newmont Metallurgical Services; Placer Dome Research Centre, Vancouver, Canada; Turquoise Ridge Underground laboratory.
In the earlier stages of Project testwork, the idea of laboratory accreditation had not been developed. In later assay campaigns, accreditations were not typically recorded in the database.
Currently, the following laboratories are used by the Nevada Operations:
•The ALS Chemex Elko and ALS Chemex Reno facilities are used for sample preparation, and hold ISO 17025 accreditation for sample preparation. The ALS Chemex facilities in Reno and in Vancouver BC are used for analytical determinations and hold ISO 17025 accreditations for selected analytical techniques. ALS Chemex is independent.
•The AAL facility located in Sparks, Nevada is used for sample preparation, analysis, and check assaying. AAL holds ISO 17025 accreditations for selected analytical techniques and is independent;
•The mine laboratories are operated by NGM personnel, are not accredited, and are not independent.
8.5 Sample Preparation
Sample preparation has varied over the more than 60 years of modern Project history, in line with advancing scientific knowledge, changes in equipment, and operational experience. Currently, sample preparation procedures include:
•ALS Chemex: drying the sample, crushing to 70% minus 10 mesh, and then pulverizing to >85% minus 200 mesh;
•AAL: drying the sample, crushing to 95% passing 10 mesh, and then pulverizing to >90% passing 105 μm (150 mesh);
•Mine laboratories: drying the sample, crushing to 65% passing 10 mesh, and then pulverizing to 80% passing 200 mesh; or crushing to 95% passing 10 mesh and pulverizing to 95% passing 175 mesh; or crushing to minus 9.5 mm, and pulverizing to 90% passing 150 mesh.
8.6 Analysis
As with sample preparation, analytical methods have changed over the Project history. Currently, sample analytical procedures include:
•ALS Chemex: fire assays (FA) and atomic absorption (AA) finish for gold; samples reporting >0.1 oz/st Au on the initial assay re-assayed by FA with gravimetric finish; cyanide leach gold assays for initial FAs >0.008 oz/st Au; cyanide leach and preg rob capacity; LECO testing; multi-element analyses by aqua regia digestion/inductively coupled plasma-atomic emission spectroscopy (ICP-AES)/ICP-mass spectroscopy (ICP-MS), 51 elements or 48 element analyses by four acid and ICP-AES/ICP-MS; other analyses may be requested, and include arsenic, total carbon, total sulfur, sulfide sulfur, carbonate carbon, and organic carbon;
•AAL: 1 assay ton fire assays with an AA finish for gold;
| | | | | | | | |
Date: February, 2022 | | Page 8-2 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
•Mine laboratories: 1 assay ton fire assays with an AA finish for gold; samples with gold grade >0.438 oz/st are completed by a ½ assay ton fire assay with a gravimetric finish. If the sample gold grade is above the open pit cut-off grade, the samples are analyzed for cyanide leach, % preg rob, total carbon, total sulfur, sulfide sulfur, carbonate, and organic carbon for ore characterization purposes. On request, underground muck samples can be equal weight composited for further ore characterization analyses including total carbon, total sulfur, sulfide sulfur, carbonate carbon, organic carbon, and arsenic.
Additional assay methods, as recorded in the Project databases were typically used for exploration or other specialized purposes such as gas sampling and were not consistently requested. They include: gravimetric, sulfuric acid digest, total copper, neutron activation analysis, X-ray diffraction (XRD), X-ray fluorescence (XRF) and pH methods.
8.7 Quality Assurance and Quality Control
Prior to the mid-1990s, few companies had rigorous quality assurance and quality control (QA/QC) programs in place. QA/QC had typically consisted, where undertaken, of reanalysis of drill core or other samples when later sampling indicated a potential problem.
In the case of the NGM Operations, QA/QC samples were submitted for RC and core samples from about 1990. Typical QA/QC measures include submission of blank materials, certified or standard reference materials (standards), and field duplicate samples. Depending on the time period, the rate of insertion of field duplicates can range from 1–5% of a field program; standard and blank insertion rates can range from between 2–5%.
NGM purchased SRMs from well-known Canadian distributors. These could be commercial standards, or standards generated from bulk samples of deposits within the NGM Operations area. Standards typically represent very high-grade, high-, medium-, and low-grade in oxide and refractory gold mineralization. Blank materials came from a variety of sources, most recently gravel purchased from local hardware stores, landscape marble, and gravel sourced from quarry sites within the operations areas.
Check assays may not be routinely performed. Typical checks were undertaken on pulps and coarse reject samples to test the analytical processes and preparation procedure, respectively.
Project geologists review the assay results and periodically request a batch re-run and/or entire hole based on expected versus actual results. Analyses that appear to be outside best practice guidelines for exploration of two standard deviations will result in a request of the laboratory that completed the original analysis to undertake a re-run of the sample batch that the failed control was in. Check assay programs are the responsibility of the individual geologists.
Several systems and programs are used to control and ensure assay data quality. These include standards for technician training, periodic process checks, equipment preventive maintenance, centralized reagent/standard preparation, control samples (reference materials) and blanks assayed with the samples, data verification, periodic check assays, and participation in industry round-robin programs.
8.8 Database
Exploration data from a variety of sources are imported into acQuire databases using a variety of techniques and procedures to check the integrity of the data entered.
| | | | | | | | |
Date: February, 2022 | | Page 8-3 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Since the mid-1990s, geological and geotechnical data have been validated by software routines and uploaded directly into the database from the field logging instruments. Analytical data are uploaded from digital sources provided by the analytical laboratories via website. Survey data are uploaded by the project geologist from digital survey files. Density data are imported by the database administrator from a spreadsheet sent from the internal mine laboratory or by download from the external laboratory website.
Verification is performed on all digitally collected data upon upload to the main database, and includes checks on surveys, collar co-ordinates, lithology data, and assay data. Data that were collected prior to the introduction of digital logging have been subject to validation, using built-in program triggers that automatically checked data upon upload to the database.
Database security and integrity are accomplished by restricting access and user level permissions that are set by the database managers. Once data entry and validation are completed for a drill hole, access is locked. There are procedures for updates that retain all the original information and prioritize use of the updates.
Digital back-up copies of the geologic logs are stored offsite. The majority of the hardcopy logs that were used prior to digital databases are archived. Some of the drill hole records have been digitally scanned and saved.
8.9 Qualified Person’s Opinion on Sample Preparation, Security, and Analytical Procedures
The sample preparation, analysis, quality control, and security procedures used by the Nevada Operations have changed over time to meet evolving industry practices. Practices at the time the information was collected were industry-standard, and frequently were industry-leading practices. The data are acceptable for use in mineral resource and mineral reserve estimates and in mine planning.
| | | | | | | | |
Date: February, 2022 | | Page 8-4 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
9.0 DATA VERIFICATION
9.1 Internal Data Verification
Validation checks are performed by NGM operations personnel on data used to support estimation comprise checks on surveys, collar coordinates, lithology data (cross-checking from photographs), and assay data. Errors noted are rectified in the database prior to data being flagged as approved for use in resource estimation.
9.2 Reviews and Audits
Newmont conducted internal audits, termed Reserve and Resource Review or 3R audits, of all its operations prior to the incorporation of the NGM JV. These audits focused on:
•Reserves processes: geology and data collection; resource modelling; geotechnical; mine engineering (long term) for open pit and underground operations; mineral processing (development); sustainability and external relations; financial model;
•Operations process: ore control; geotechnical and hydrogeology (operational); mine engineering (operational) for open pit and underground operations; mineral processing (operational); reconciliation.
The reviews assessed these areas in terms of risks to the contained metal content of the mineral resource and mineral reserve estimates, or opportunities to add to the estimated contained metal content. Findings were by definition areas of incorrect or inappropriate application of methodology or areas of non-compliance to the relevant internal Newmont standard (e.g., such as documents setting out the standards that are expected for aspects of technical services, environmental, sustainability and governmental relations) or areas which are materially inconsistent with published Newmont guidelines (e.g., such as guidelines setting out the protocols and expectations for mineral resource and mineral reserve estimation and classification, mine engineering, geotechnical, mineral processing, and social and sustainability). The operation under review was expected to address findings based on the level of criticality assigned to each finding.
The most recent 3R audits on the former Newmont properties were conducted as follows:
•2013: Emigrant, Phoenix, and Long Canyon;
•2014: Leeville;
•2015: Phoenix;
•2016: Carlin, Twin Creeks;
•2018: Carlin, Phoenix.
9.3 Subject Matter Expert Reviews
The QP requested that information, conclusions, and recommendations presented in the body of this Report be reviewed by Newmont experts or Newmont staff in each discipline area as a further level of data verification.
| | | | | | | | |
Date: February, 2022 | | Page 9-1 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Reviewers were requested to cross-check, as applicable, numerical data, flag any data omissions or errors identified, review the manner in which the data were summarized and reported in the technical report summary, and check the interpretations arising from the data as presented in the Report. Reviewers were also asked to check that the QP’s opinions stated as required in certain Report chapters were supported by the data.
Feedback from the reviewers was incorporated into the Report as required.
9.4 External Data Verification
A number of third-party consultants have performed external data reviews, as summarized in Table 9-1.
These external reviews were undertaken in support of acquisitions, support of feasibility-level studies, and in support of technical reports, producing independent assessments of the database quality. No significant problems with the database, sampling protocols, flowsheets, check analysis program, or data storage were noted.
9.5 Data Verification by Qualified Person
Mr. Doe performed site visits as outlined in Chapter 2.4. Observations made during the visits, in conjunction with discussions with site-based technical staff also support the geological interpretations, and analytical and database quality. The QP’s personal inspection supports the use of the data in mineral resource and mineral reserve estimation, and in mine planning.
Mr. Doe has a long history of involvement with mining operations in Nevada, beginning in 1994. This consisted of site-based and corporate roles, including his current position as Group Executive Reserves.
In October 2021, Mr. Doe supervised a site-based review of the geological and geostatistical information supporting the mineral resources and mineral reserves as part of Newmont’s 3R process. The review indicated that the estimates were performed used industry-standard practices.
A subsequent in-person review by the QP and mining, metallurgical, geotechnical and tailings engineers, and environmental experts was planned for November 2021. However, due to Covid-19 protocols, this review was performed remotely. The review indicated that there may be some risk to the permitting timelines for tailings expansion at the Turquoise Ridge Complex.
| | | | | | | | |
Date: February, 2022 | | Page 9-2 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 9-1: External Data Reviews
| | | | | | | | |
Consultant | Year | Comment |
Second Door Industries | 2000 | Review of Turquoise Ridge Underground database |
AGRA Simons | 2000 | Review of Phoenix databases |
J.M. Rendu | 2002–2003 | Review of Gold Quarry databases |
AMEC Americas Ltd | 2004–2005 | Review of Cortez Hills databases |
Ed Isaaks | 2005 | Review of Phoenix databases |
AMEC Americas Ltd | 2006–2007 | Review of Phoenix databases |
AMEC Americas Ltd | 2009 | Review of Leeville databases |
Mine Development Associates | 2009 | Data review of Long Canyon database in support of NI 43-101 Technical Report |
Roscoe Postle Associates | 2011 | Review of Leeville databases |
2012 | Review of Cortez databases and mineral resource/mineral reserve estimates |
Roscoe Postle Associates | 2015 | Review of Cortez databases |
2018 | Data review of Cortez operations in support of NI 43-101 Technical Report |
Mine Technical Services | 2018 | Review of Goldstrike databases |
Review of Cortez databases |
Golder Associates | 2018 | Review of Goldstrike databases |
Wood plc | 2019 | Review of estimation, geologic modelling and exploratory data analysis methods at Cortez |
AB Global Mining | 2020 | Review of Cortez Hills underground, Crossroads, Cortez Pits and Robertson Mineral Resource models |
Roscoe Postle Associates | 2020 | Mineral Reserve and Mineral Resource audit of the Goldstrike mine |
SRK Consulting | 2021 | Quantified comparison and adequacy of NGM’s digital database against original source data |
9.6 Qualified Person’s Opinion on Data Adequacy
The process of data verification for the Project has been performed by external consultancies and NGM personnel. The QP considers that a reasonable level of verification has been completed, and that no material issues would have been left unidentified from the programs undertaken.
The QP, who relies upon this work, has reviewed the reports and is of the opinion that the data verification programs completed on the data collected from the Project are consistent with industry best practices and that the database is sufficiently error-free to support the geological interpretations and mineral resource and mineral reserve estimation, and mine planning.
| | | | | | | | |
Date: February, 2022 | | Page 9-3 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
10.0 MINERAL PROCESSING AND METALLURGICAL TESTING
10.1 Test Laboratories
During the 60+ year history of Nevada Operations mine development, a significant number of metallurgical studies and accompanying laboratory-scale and/or pilot plant tests have been completed. Either internal metallurgical research facilities or external consultants undertake the research. Recent external testwork was performed at McClelland Laboratories, Hazen Research, Macpherson Laboratories, McGill University, Svedala, and Outukumpu. Internal testwork facilities included the Goldstrike Metallurgical Laboratory, Gold Quarry Metallurgical Laboratory, Newmont Metallurgical Services in Englewood, Colorado and the AuTec Metallurgical Laboratory located in Vancouver, British Columbia, Canada,
The laboratories perform metallurgical testing using industry-accepted procedures and to industry-accepted standards. There is no international standard of accreditation provided for metallurgical testing laboratories or metallurgical testing techniques.
10.2 Metallurgical Testwork
Metallurgical testwork included: mineralogy; head grades and screen analyses; bottle roll, bench and column cyanide leaching; carbon adsorption/activation tests; direct cyanide leach testwork; carbon-in-leach tests; agglomeration tests; cyanide amenability tests; bench or circulating fluidized bed roasting tests; calcine tests; magnetic separation testwork; bench-top roaster followed by CIL testwork; bench-top alkaline pressure leach tests followed by CIL tests; calcium thiosulfate and resin leach tests; bench-top alkaline pressure leach tests followed by thiosulfate resin in leach testwork; sulfidization acidification re-neutralization and thickening or SART testwork; reagent consumption reviews; impurity reviews; standard autoclaving and leach tests; grindability (comminution) tests (SMC, breakage parameter, Bond work index, drop weight index, rod work index, unconfined compressive strength, semi-autogenous grind (SAG) power index); thickener testwork; batch and pilot plant tests
These test programs were sufficient to establish the optimal processing routes for the non-refractory and refractory ores, and the weathering state of the ores (oxide, leached, enriched, transition, sulfide), and was performed on mineralization that was typical of the deposits. The results obtained supported estimation of recovery factors for the various ore types depending on the process method selected.
Numerous processing methods are used within the Nevada Operations, including CIL for higher-grade oxide ore, heap leaching for lower-grade oxide ore, roasting for carbonaceous refractory ore, and pressure oxidation (POX) for higher-grade sulfidic ore.
Future ore testing is completed according to the needs of the optimized blend planning for the combined NGM operations. A sampling matrix of ore types and grade/chemistry ranges is developed. The sampling matrix is used to perform an extraction on the resource model to determine tons in each matrix category. Core logs are used to build variability composites for each matrix category targeting a minimum of the one variability composite for every 1.5 Mt. All variability composites are laboratory-tested, and include: column testwork, roast and bottle roll leach testwork, and flotation and bottle roll leach testwork as applicable. Master composites are
| | | | | | | | |
Date: February, 2022 | | Page 10-1 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
generated from the variability composites to identify any negative or positive synergies that could result from mixing ore types.
Current ore testing is completed monthly by performing testwork on feed stockpile samples. The stockpile samples are taken weekly and composited at the end of the month for column testwork, roast and bottle roll leach testwork, and flotation and bottle roll leach testwork as applicable. The stockpile metallurgical testwork is completed individually so that recovery results can be compared to budget/reserve recoveries and adjusted as needed.
10.3 Recovery Estimates
Gold recovery is a function of the processing method (e.g., heap leaching, CIL, roasting, and arsenic concentration for refractory ore) and the lithology of the mineralization being processed. As applicable, recovery estimates include consideration of the head grade, cyanide-soluble gold to fire assay gold ratio, sulfide sulfur concentration, total organic carbon concentration, and silica concentration.
Copper recovery models were derived from a statistical review of the metallurgical data and range in complexity from simple, fixed recoveries to complex, multi-variable equations. The following input variables were available as possible drivers of recovery: head grade, copper leach ore type, alteration type, formation, and various trace elements.
Recovery ranges projected for the LOM operations include:
•Gold:
◦Oxide leach: 57–75%;
◦Oxide mill: 73–88%;
◦Goldstrike roaster: 84–92%;
◦Goldstrike autoclave: 50–96%;
◦Gold Quarry roaster: 84–92%;
◦Sage (Turquoise Ridge) autoclave: average 84%;
◦Phoenix mill: average 70%;
•Copper:
◦Phoenix mill: average 71%;
◦Copper leach: average 49%;
•Silver:
◦Phoenix mill: average 38%.
10.4 Metallurgical Variability
Samples selected for metallurgical testing during feasibility and development studies were representative of the various styles of mineralization within the different deposits. Samples were selected from a range of locations within the deposits. Sufficient samples were taken, and tests were performed using sufficient sample mass for the respective tests undertaken.
| | | | | | | | |
Date: February, 2022 | | Page 10-2 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Variability assessments are supported by production and extensive open pit and underground exposures.
10.5 Deleterious Elements
Depending upon the specific processing facility, several processing factors or deleterious elements could have an economic impact on extraction efficiency of a certain ore source, based either on the presence, absence, or concentration of the following constituents in the processing stream:
•Organic carbon;
•Sulfide sulfur;
•Carbonate carbon;
•Arsenic
•Mercury;
•Antimony;
•Copper.
However, under normal ore routing and blending practices at NGM where material from several sites may be processed at one facility, the above list of constituents is typically not a concern.
10.6 Qualified Person’s Opinion on Data Adequacy
Industry-standard studies were performed as part of process development and facility designs. Subsequent production experience and focused investigations guided facility alterations and process changes where required.
Testwork programs, both internal and external, continue to be performed to support current operations and potential improvements. From time to time, this may lead to requirements to adjust cut-off grades, modify the process flowsheet, or change reagent additions and process parameters to meet production, and economic targets.
Based on these checks, the metallurgical testwork and reconciliation and production data support the estimation of mineral resources and mineral reserves, and the inputs to the economic analysis.
The facilities will produce variations in recovery due to the day-to-day changes in ore type or combinations of ore type being processed. These variations are expected to trend to the forecast recovery value for monthly or longer reporting periods.
| | | | | | | | |
Date: February, 2022 | | Page 10-3 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
11.0 MINERAL RESOURCE ESTIMATES
11.1 Introduction
Mineral resources were estimated for the deposits listed in Table 2-1. The close-out date for the databases used in the various mineral resource estimates depend on the deposit. Geology models were generally constructed by Nevada Operations personnel.
Estimation was typically performed by Nevada Operations personnel. All mineralogical, drilling, and background data and information were provided to the estimators by the geological staff at the operations or by exploration staff. Depending on the deposit, models were developed as follows:
•Vulcan: surface wireframes were constructed representing interpreted structure (faults) and stratigraphy units. Stratigraphic logging was the primary driver for the geological modelling; however, geological mapping, structural logging, and gold and sulfur assay data were also used to guide the interpretation;
•Leapfrog: major faults, stratigraphy units, weathering surfaces and mineralized grade shells were interpreted;
Block sizes were based on the drill hole spacing, deposit geometry, and the potential mining method. Parent block sizes for assumed open pit operations included: 30 x 30 x 20 ft, 40 x 40 x 20 ft, 50 x 50 x 20 ft; with sub-cells, where necessary, at, 11.5 x 11.5 x 11.5 ft. Underground parent block sizes included 10 x 10 x 2 ft, 10 x 10 x 10 ft, 20 x 20 x 20 ft, 30 x 30 x 20 ft, 30 x 30 x 50 ft; with sub-cells, where necessary, at 2.5 x 2.5 x 2 ft and 5 x 5 x 2 ft.
11.2 Exploratory Data Analysis
Exploratory data analytical methods varied by complex. Typically, data analysis was completed on raw and composited data to determine statistics for sample populations within domains, and the mean, maximum, minimum values, standard deviation and coefficients of variance were tabulated. Exploratory data analysis could be used to determine estimation domains, evaluate composite lengths, identify any grade outliers and to select optimum top cut values for each of the domains and to determine estimation parameters. The analysis tools applied could include for capping and estimation parameter investigation: histogram plots, log probability plots, mean and co-efficient of variation (CV) curves to look for the stability point, top 5% metal impact, indicator correlation, declustered mean plus two and three standard deviations, risk-hi analysis, contact analysis, visual checking and metal impact.
11.3 Geological Models
Geologic modeling included lithologies, structures, alteration and mineralization in order to build a 3D interpretation of the important features controlling the orebodies. These interpretations used all available information as a basis, including drill assays and logs, geochemical relationships, mapping, and current understanding of mineralization genesis in the region. Within the interpreted geologic framework, estimation domains were developed through collaboration between the project geologists and modelers.
| | | | | | | | |
Date: February, 2022 | | Page 11-1 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
11.4 Density Assignment
Density values were typically assigned based on lithology; alternatively, a tonnage factor could be applied to material designated as either ore or waste. Where sufficient local data were available, density was estimated using similar data analysis, estimation, and validation methods as for other estimated elements.
11.5 Grade Capping/Outlier Restrictions
Grade caps were applied based on the results of the exploratory data analysis. High-grade anomalous values were controlled through the use of top-cutting and/or high-grade estimation restrictions, applied by deposit and domain. Where multiple indicator kriging (MIK) or similar estimation methods were used, the high-grade portion of the distribution was evaluated and validated accordingly.
11.6 Composites
Composite lengths varied by complex and project, based on block sizes, sample lengths, and estimation workflow, including:
•Open pit: 10 ft, 11.5 ft, 20 ft;
•Underground: 2.5 ft, 5 ft, 10 ft, 11.5 ft.
11.7 Variography
Variographic analyses were completed by domain, using Snowden Supervisor, Vulcan, or Sage software, or GSLib/CCG programs, to determine a3D model of spatial continuity. Variogram or correlogram models were fitted to experimental variograms where sufficient data existed within the domain. Search ellipses for use in the various estimation passes were scaled according to the relative axis dimensions and orientations for each estimation domain. Visual checks of the search ellipses against the underlying geologic model and interpreted mineralization controls to ensure consistency were done using Vulcan in 3D.
11.8 Estimation/interpolation Methods
Estimation and interpolation methods varied by deposit, domain, and estimation element. The following methods were used: ordinary kriging (OK), MIK, localized indicator kriging (LIK), inverse distance weighting to the second power (ID2), inverse distance weighting to the third power (ID3), and inverse distance weighting to the fifth power (ID5). Typically, alternate grade interpolations (including nearest neighbor) were performed for use in model validation and sensitivity testing.
Depending on the deposit, interpolation was performed in multiple (usually 2–3, but as many as eight) passes. Search neighborhoods were based on variography, mineralization geometry, or on selected drill spacings. Minimum and maximum numbers of informing samples varied by deposit, as did the number of samples allowed to be used from a single drill hole:
•Minimum number of informing samples: 1–5;
| | | | | | | | |
Date: February, 2022 | | Page 11-2 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
•Maximum number of informing samples: 5–24;
•Maximum number of informing samples from a single drill hole: 2–3.
Dynamic anisotropy and unfolding applications could be used to improve alignment of the local sample search ellipse with changes in the strike, dip, and plunge orientation of the mineralization.
Block models were flagged for mining depletion. A depleted version was completed with blocks within previously-mined areas depleted for grades and densities. Where areas were back-filled, these blocks were coded by fill type and their density reset to reflect the fill type.
11.9 Validation
Mineralization solids were checked for conformity to drill hole data, continuity, similarity between sections, overlaps, appropriate terminations between holes and into undrilled areas.
Validation procedures were undertaken on the estimations. These could include comparison of global mean grades, visual comparisons to composite grades, comparisons to reconciliation (when available), change of support corrections estimated using a discrete Gaussian model under a diffusion model assumption, grade-tonnage curves, slope of regression calculations, comparison to NN analysis and swath plots.
No significant biases were noted from the checks.
11.10 Confidence Classification of Mineral Resource Estimate
Blocks were classified in the model, based on relative confidence in the estimated grades, into measured, indicated, and inferred. Criteria for classification were defined within each deposit, and based on various combinations of:
•Proximity to nearby drilling data (distances to nearest 1, 2, or 3 drill holes);
•Geostatistical drill spacing studies;
•Qualitative assessment of confidence in the underlying geologic interpretations;
•Historical classification assignments;
•Classification smoothing algorithms.
Local zones could be manually reclassified, using solids where required, due to lower confidence in the interpretation or estimate.
11.11 Reasonable Prospects of Economic Extraction
For each resource estimate, an initial assessment was undertaken that assessed likely infrastructure, mining, and process plant requirements; mining methods; process recoveries and throughputs; environmental, permitting and social considerations relating to the proposed mining and processing methods, and proposed waste disposal, and technical and economic considerations in support of an assessment of reasonable prospects of economic extraction.
| | | | | | | | |
Date: February, 2022 | | Page 11-3 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
11.11.1 Input Assumptions
Mineralization considered potentially amenable to open pit mining methods was constrained within a conceptual pit shell using the Lerchs–Grossmann (LG) algorithm within Vulcan software.
Mineralization considered potentially amenable to open pit mining methods was constrained within mineable shapes generated using Mineable Stope Optimizer (MSO) software.
Key parameters used to constrain the resource estimates are summarized in Table 11-1 (open pits) and Table 11-2 (underground). Tonnages in the tables are metric tonnes.
11.11.2 Commodity Price
Commodity prices used in resource estimation are based on long-term analyst and bank forecasts. An explanation of the derivation of the commodity prices is provided in Chapter 16.2. The estimated timeframe used for the price forecasts is the 24-year LOM that supports the mineral reserve estimates.
11.11.3 Cut-off
The resources are reported at varying cut-off values, which are based on the material type being mined, the mining method and the designated process facility. As a result, cut-off values can vary significantly by material type.
11.11.4 QP Statement
The QP is of the opinion that any issues that arise in relation to relevant technical and economic factors likely to influence the prospect of economic extraction can be resolved with further work. The mineral resource estimates are performed for deposits that are in a well-documented geological setting; the district has seen 55+ years of active open pit operations and 25+ years of underground mining operations conducted by Newmont, Barrick and NGM; Newmont is familiar with the economic parameters required for successful operations in the Nevada Operations area; and Newmont, Barrick and NGM have a history of being able to obtain and maintain permits, social license and meet environmental standards in Nevada. The 24-year timeframe is considered sufficient to address any issues that may arise with the mineral resource estimates.
| | | | | | | | |
Date: February, 2022 | | Page 11-4 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 11-1: Open Pit Input Parameters (mineral resources)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Economic Parameters | Units | Carlin Complex | Cortez Complex | Long Canyon Complex | Phoenix Complex | Turquoise Ridge Complex |
Minimum | Maximum | Minimum | Maximum | Minimum | Maximum | Minimum | Maximum | Minimum | Maximum |
Gold price | US$/oz | 1,500 | 1,500 | 1,500 | 1,500 | 1,500 | 1,500 | 1,500 | 1,500 | 1,500 | 1,500 |
Royalties | % | 0 | 16 | 0.73 | 11 | 0 | 0 | 0.74 | 0.74 | 1 | 1 |
Discount rate | % | 0.28 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | Varies, maximum of 5 |
Mining cost | US$/t | 2.08 | 2.08 | 1.80 | 2.42 | 3.80 | 3.80 | 2.63 | 2.81 | 2.51 | 2.57 |
G&A cost | US$/t | 0.23 | 0.23 | 0.19 | 2.84 | 0.28 | 0.28 | 0.82 | 0.82 | 0.27 | 0.28 |
Process cost | US$/t | 2.35 | 40.87 | 2.44 | 9.77 | 3.79 | 3.79 | 8.05 | 8.05 | 5.78 | 35.12 |
% (average) | 52 | 67 | 62 | 88 | 75 | 82 | 66 | 67 | 57 | 81 |
Pit slope angles | degrees | 11 | 47 | 25 | 51 | 50 | 52 | 25 | 52 | 36 | 50 |
Cut-off grades | g/t Au | 0.21 | 1.10 | 0.171 | 1.47 | 0.202 | 0.202 | NA | NA | 0.17 | 3.29 |
Note: NA = not applicable. Phoenix is reported using a net smelter return cut-off. Tonnages are metric tonnes.
Table 11-2: Underground Input Parameters (mineral resources)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Economic Parameters | Units | Carlin Complex | Cortez Complex | Long Canyon | Turquoise Ridge Complex |
Minimum | Maximum | Minimum | Maximum | Minimum | Maximum | Minimum | Maximum |
Gold price | US$/oz | 1,500 | 1,500 | 1,500 | 1,500 | 1,200 | 1,200 | 1,500 | 1,500 |
Royalties | % | 0.56 | 6 | 1 | 3 | NA | NA | 1 | 1 |
Discount rate | % | Variable, maximum of 5 | 5 | 5 | NA | NA | NA | NA |
Mining cost | US$/t | 61.30 | 145.63 | 31.97 | 97.15 | 122.14 | 122.14 | 134.75 | 213.89 |
G&A cost | US$/t | 9.44 | 15.67 | 10.79 | 15.19 | 15.75 | 15.75 | 17.45 | 17.45 |
Process cost | US$/t | 18.31 | 26.20 | 10.62 | 29.4 | 55.31 | 55.31 | 34.91 | 34.91 |
% (average) | 79 | 85 | 84 | 89 | 83 | 92 | 86 | 90 |
Cut-off grades | g/t Au | 2.74 | 5.73 | 2.71 | 3.41 | 7.37 | 7.37 | 3.3 | 6 |
Note: NA = not applicable. Tonnages are metric tonnes.
| | | | | | | | |
Date: February, 2022 | | Page 11-5 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
11.12 Mineral Resource Statement
Mineral resources are reported using the mineral resource definitions set out in SK1300. The point of reference for the estimate is the point of delivery to the process facilities. Mineral resources are reported exclusive of those mineral resources converted to mineral reserves. Mineral resources are reported on a 100% basis. Barrick owns a 61.5% JV interest, with Newmont owning the remaining 38.5% JV interest.
The mineral resource estimates for the Nevada Operations are provided as follows:
•Gold: Table 11-3 (measured and indicated) and Table 11-4 (inferred);
•Silver: Table 11-5 (measured and indicated) and Table 11-6 (inferred);
•Copper: Table 11-7 (measured and indicated) and Table 11-8 (inferred).
| | | | | | | | |
Date: February, 2022 | | Page 11-6 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 11-3: Measured and Indicated Mineral Resource Statement (Gold)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Deposits | Type | Measured Mineral Resources | Indicated Mineral Resources | Measured and Indicated Mineral Resources |
Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) |
Carlin | Open pit | 18,800 | 2.66 | 1,610 | 131,500 | 1.49 | 6,320 | 150,400 | 1.64 | 7,930 |
Underground | 18,200 | 5.67 | 3,320 | 8,500 | 5.35 | 1,460 | 26,700 | 5.57 | 4,780 |
Stockpiles | 8,400 | 1.02 | 280 | — | — | — | 8,400 | 1.02 | 280 |
Carlin Sub-total | 45,400 | 3.56 | 5,210 | 140,100 | 1.73 | 7,780 | 185,500 | 2.18 | 12,980 |
Cortez | Open pit | 0 | 1.64 | 0 | 89,300 | 0.68 | 1,940 | 89,400 | 0.68 | 1,940 |
Underground | 700 | 7.17 | 170 | 10,200 | 5.84 | 1,910 | 10,900 | 5.93 | 2,070 |
Cortez Sub-total | 700 | 7.02 | 170 | 99,500 | 1.20 | 3,850 | 100,300 | 1.25 | 4,010 |
Long Canyon | Open pit | 500 | 3.47 | 60 | 8,000 | 2.56 | 660 | 8,600 | 2.62 | 720 |
Underground | — | — | — | 1,800 | 10.68 | 620 | 1,800 | 10.68 | 620 |
Long Canyon Sub-total | 500 | 3.47 | 60 | 9,800 | 4.05 | 1,280 | 10,400 | 4.02 | 1,340 |
Turquoise Ridge | Open pit | 800 | 3.13 | 80 | 23,200 | 2.05 | 1,540 | 24,000 | 2.09 | 1,610 |
Underground | 3,200 | 6.84 | 710 | 10,500 | 6.93 | 2,330 | 13,700 | 6.91 | 3,040 |
Stockpiles | 11,400 | 2.04 | 740 | — | — | — | 11,400 | 2.04 | 740 |
Turquoise Ridge Sub-total | 15,300 | 3.10 | 1,530 | 33,700 | 3.57 | 3,870 | 49,100 | 3.42 | 5,400 |
Phoenix | Open pit | 7,600 | 0.53 | 130 | 218,200 | 0.45 | 3,140 | 225,800 | 0.45 | 3,270 |
Phoenix Sub-total | 7,600 | 0.53 | 130 | 218,200 | 0.45 | 3,140 | 225,800 | 0.45 | 3,270 |
Grand Total | 69,600 | 3.17 | 7,090 | 501,300 | 1.24 | 19,910 | 571,100 | 1.47 | 27,000 |
| | | | | | | | |
Date: February, 2022 | | Page 11-7 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 11-4: Inferred Mineral Resource Statement (Gold)
| | | | | | | | | | | | | | |
Deposits | Area | Inferred Mineral Resources |
Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) |
Carlin | Open pit | 89,100 | 1.1 | 3,230 |
Underground | 16,200 | 7.5 | 3,930 |
Stockpiles | 5,400 | 2.0 | 350 |
Carlin Sub-total | 110,700 | 2.1 | 7,510 |
Cortez | Open pit | 100,100 | 0.5 | 1,760 |
Underground | 24,300 | 5.9 | 4,620 |
Cortez Sub-total | 124,400 | 1.6 | 6,380 |
Long Canyon | Open pit | 1,700 | 0.8 | 50 |
Underground | 900 | 9.1 | 250 |
Long Canyon Sub-total | 2,600 | 3.6 | 300 |
Turquoise Ridge | Open pit | 17,100 | 1.8 | 980 |
Underground | 1,100 | 6.2 | 220 |
Turquoise Ridge Sub-total | 18,200 | 2.0 | 1,200 |
Phoenix | Open pit | 41,400 | 0.3 | 430 |
Stockpiles | 7,800 | 0.6 | 160 |
Phoenix Sub-total | 49,200 | 0.4 | 580 |
NGM Total | Grand Total | 305,000 | 1.6 | 15,970 |
Table 11-5: Measured and Indicated Mineral Resource Statement (Silver)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Deposits | Type | Measured Mineral Resources | Indicated Mineral Resources | Measured and Indicated Mineral Resources |
Tonnage (x 1,000 t) | Grade (g/t Ag) | Cont. Silver (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Ag) | Cont. Silver (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Ag) | Cont. Silver (x 1,000 oz) |
Phoenix | Open pit | 7,600 | 5.572 | 1,360 | 218,200 | 5.539 | 38,860 | 225,800 | 5.540 | 40,220 |
Stockpiles | — | — | — | | — | — | — | — | — |
Phoenix sub-total | 7,600 | 5.572 | 1,360 | 218,200 | 5.539 | 38,860 | 225,800 | 5.540 | 40,220 |
NGM Total | Grand Total | 7,600 | 5.572 | 1,360 | 218,200 | 5.539 | 38,860 | 225,800 | 5.540 | 40,220 |
| | | | | | | | |
Date: February, 2022 | | Page 11-8 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 11-6: Inferred Mineral Resource Statement (Silver)
| | | | | | | | | | | | | | |
Deposits | Area | Inferred Mineral Resources |
Tonnage (x 1,000 t) | Grade (g/t Ag) | Cont. Silver (x 1,000 oz) |
Phoenix | Open pit | 41,400 | 5.4 | 7,240 |
Stockpiles | 7,800 | 6.4 | 1,600 |
Phoenix sub-total | 49,200 | 5.6 | 8,840 |
NGM Total | Grand Total | 49,200 | 5.6 | 8,840 |
Table 11-7: Measured and Indicated Mineral Resource Statement (Copper)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Deposits | Area | Measured Mineral Resources | Indicated Mineral Resources | Measured and Indicated Mineral Resources |
Tonnage (x 1,000 t) | Grade (Cu %) | Cont. Copper (M lbs) | Tonnage (x 1,000 t) | Grade (Cu %) | Cont. Copper (M lbs) | Tonnage (x 1,000 t) | Grade (Cu %) | Cont. Copper (M lbs) |
Phoenix | Open pit | 8,000 | 0.14 | 20 | 289,600 | 0.14 | 880 | 297,600 | 0.14 | 910 |
Phoenix sub-total | 8,000 | 0.14 | 20 | 289,600 | 0.14 | 880 | 297,600 | 0.14 | 910 |
NGM Total | Grand Total | 8,000 | 0.14 | 20 | 289,600 | 0.14 | 880 | 297,600 | 0.14 | 910 |
Table 11-8: Inferred Mineral Resource Statement (Copper)
| | | | | | | | | | | | | | |
Deposits | Area | Inferred Mineral Resources |
Tonnage (x 1,000 t) | Grade (Cu %) | Cont. Copper (M lbs) |
Phoenix | Open pit | 43,300 | 0.1 | 140 |
Stockpiles | 8,300 | 0.1 | 10 |
Phoenix sub-total | 51,600 | 0.1 | 150 |
NGM Total | Grand Total | 51,600 | 0.1 | 150 |
Notes to Accompany Mineral Resource Tables:
1.Mineral resources are current as at December 31, 2021, using the definitions in SK1300. The Qualified Person responsible for the estimate is Mr. Donald Doe, RM SME, Group Executive, Reserves, a Newmont employee.
| | | | | | | | |
Date: February, 2022 | | Page 11-9 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
2.The reference point for the mineral resources is in situ.
3.Mineral resources are reported on a 100% basis. Barrick owns a 61.5% JV interest, with Newmont owning the remaining 38.5% JV interest.
4.Mineral resources are reported exclusive of mineral reserves. Mineral resources that are not mineral reserves do not have demonstrated economic viability.
5.Mineral Resources that are potentially amenable to open pit mining methods are constrained within a designed pit shell. Mineral Resources that are potentially amenable to underground mining methods are constrained within conceptual stope designs. Parameters used are summarized in Table 11-1 and Table 11-2.
6.Tonnages are metric tonnes rounded to the nearest 100,000. Gold and silver grades are rounded to the nearest 0.01 gold grams per tonne. Copper grade is in %. Gold and silver ounces and copper pounds are estimates of metal contained in tonnages and do not include allowances for processing losses. Contained (cont.) gold and silver ounces are reported as troy ounces, rounded to the nearest 10,000. Copper is reported as pounds and rounded to the nearest 10 million pounds. Rounding of tonnes and contained metal content as required by reporting guidelines may result in apparent differences between tonnes, grade and contained metal content. Due to rounding, some cells may show a zero (“0”). Totals may not sum due to rounding.
| | | | | | | | |
Date: February, 2022 | | Page 11-10 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
11.13 Uncertainties (Factors) That May Affect the Mineral Resource Estimate
Areas of uncertainty that may materially impact all of the mineral resource estimates include:
•Changes to long-term metal price and exchange rate assumptions;
•Changes in local interpretations of mineralization geometry such as pinch and swell morphology, extent of brecciation, presence of unrecognized mineralization off-shoots; faults, dykes and other structures; and continuity of mineralized zones;
•Changes to geological and grade shape, and geological and grade continuity assumptions;
•Changes to variographical interpretations and search ellipse ranges that were interpreted based on limited drill data, when closer-spaced drilling becomes available;
•Changes to metallurgical recovery assumptions;
•Changes to the input assumptions used to derive the potentially-mineable shapes applicable to the assumed underground and open pit mining methods used to constrain the estimates;
•Changes to the forecast dilution and mining recovery assumptions;
•Changes to the cut-off values applied to the estimates;
•Variations in geotechnical (including seismicity), hydrogeological and mining method assumptions;
•Changes to environmental, permitting and social license assumptions.
Specific factors that may affect individual estimates include:
•Cortez Complex: Mineralization at the Robertson deposit is genetically different to the mineralization currently mined within the Cortez Complex. Additional metallurgical testwork is planned, and results from this work may impact options for processing the mineralization and subsequent recovery expectations;
•Long Canyon Complex: the mineral resource estimate includes an assumption of underground mining for a portion of the estimate. Underground mining operations are new to the Long Canyon Complex;
•Phoenix Complex: optimization is based on the combined value of recovered gold, silver and copper. Changes to the price of one or more commodities may impact the optimization.
| | | | | | | | |
Date: February, 2022 | | Page 11-11 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
12.0 MINERAL RESERVE ESTIMATES
12.1 Introduction
Measured and indicated mineral resources were converted to mineral reserves. Mineral reserves in the Nevada Operations area are estimated for the Carlin, Cortez, Long Canyon, Phoenix and Turquoise Ridge complexes using open pit mining, and the Carlin, Cortez, and Turquoise Ridge complexes using underground mining. Stockpiled material is also included in the mineral reserve estimates. All Inferred blocks are classified as waste in the cashflow analysis that supports mineral reserve estimation.
Mineral Reserves are supported by a mine plan, an engineering analysis, and the application of modifying factors. These inputs are supported by operational experience.
12.2 Open Pit Estimates
The optimized economic pit shells selected for the basis of open pit designs were created using the Whittle 4X software package. Optimization work involved floating cones at a series of gold prices. The generated nested pit shells were evaluated using the reserve gold price of US$1,200/oz (and at Phoenix a copper price of $2.75/lb and silver price of $16.50/oz) and a 5% discount rate. The pit shells with the highest NPV were selected for detailed engineering design work.
A realistic schedule was developed in order to determine the optimal pit shell for each deposit; schedule inputs include the minimum mining width, and vertical rate of advance, mining rate and mining sequence.
Operating costs for mining, processing, and general and administrative were developed as part of the mine business planning process. The costs build-up is based on actual values, as well as inclusion of a number of projected cost-saving measures and efficiency gains. Costs are un-escalated.
Costs were based on the following key inputs:
•The equipment fleet required through to the end of mine life;
•Process costs for each pit and material type, derived from actual costs and forecast ore feed blends;
•Reclamation and closure cost provisions sourced from site environmental calculations.
Dilution and extraction for the open pits are addressed by using whole blocks, without any further external factors. The block models were constructed to include the expected dilution based on mining methods, bench height and other factors. The current mine and process reconciliation data appear to support this assumption.
Input parameters used are summarized in Table 12-1.
| | | | | | | | |
Date: February, 2022 | | Page 12-1 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 12-1: Input Parameters, Open Pit (mineral reserves)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Economic Parameters | Units | Carlin Complex | Cortez Complex | Long Canyon Complex | Phoenix Complex | Turquoise Ridge Complex |
Minimum | Maximum | Minimum | Maximum | Minimum | Maximum | Minimum | Maximum | Minimum | Maximum |
Gold price | US$/oz | 1,200 | 1,200 | 1,200 | 1,200 | 1,200 | 1,200 | 1,200 | 1,200 | 1,200 | 1,200 |
Royalties | % | 0.56 | 16 | 1 | 11 | 0 | 0 | 0.74 | 0.74 | 1 | 1 |
Discount rate | % | 0.28 | 5 | 10 | 10 | NA | NA | NA | NA | NA | NA |
Mining cost | US$/t | 2.08 | 2.08 | 1.80 | 2.42 | 3.80 | 3.80 | 2.63 | 2.83 | 1.64 | 1.65 |
G&A cost | US$/t | 0.23 | 0.23 | 0.19 | 2.84 | 0.28 | 0.28 | 0.46 | 1.17 | 0.64 | 2.94 |
Process cost | US$/t | 2.35 | 40.87 | 2.44 | 9.77 | 3.79 | 3.79 | 1.90 | 8.87 | 6.74 | 25.44 |
% (average) | 54 | 66 | 62 | 88 | 75 | 75 | 69 | 73 | 57 | 81 |
Pit slope angles | º | 11 | 47 | 25 | 51 | 45 | 50 | 25 | 52 | 36 | 50 |
Cut-off grades | g/t Au | 0.21 | 0.99 | 0.14 | 2.06 | 0.24 | 0.24 | NA | NA | 0.17 | 3.09 |
Note: NA = not applicable. Phoenix is reported using a net smelter return cut-off. Tonnages are metric tonnes.
| | | | | | | | |
Date: February, 2022 | | Page 12-2 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
12.3 Underground Estimates
Underground mines are designed using zones that are amenable to different mining methods based on geotechnical and access considerations, the deposit shape, orientation and grade, and mining depths.
The mine plans assume use of a number of different mining methods and variants including:
•Long-hole stoping;
•Long-hole stope retreat
•Underhand drift-and-fill;
•Overhand drift-and-fill.
Stopes were created using MSO software at the required stope height, length and cut-off criteria based on the mine area. The stope widths depend on the stope cut-off and dilution (over-break) added to stope design, and the mining method used. A set of marginal stopes could also be considered in the reserve process. These stopes were assessed for reserve reporting based on an individual economic assessment. Typically, these stopes were adjacent to higher-grade stopes and thus required minimal waste development and infrastructure.
Blocks that were modelled as waste or low-grade were included in a designed stope shape as internal dilution. Additional tonnage dilution percentages could be added by site personnel, where required, based on historical reconciliation data for a particular mining method. Dilution accommodations (tonnage at no grade) can be made to account for ore handling and cemented rock fill dilution.
Mineral reserves include adjustments for ore losses and dilution.
Input parameters used are summarized in Table 12-2.
12.4 Cut-offs
Cut-off grades are determined based on a combination of the selected metal price, applicable royalty payments, mining costs, process operating costs, and on-site (and off-site) metal recoveries by material type, selected process method, and mining method. Operational cut-off grades ranged from:
•Carlin Complex: 0.20–7.06 g/t Au;
•Cortez Complex: 0.14–3.41 g/t Au;
•Long Canyon: 0.24 g/t Au;
•Turquoise Ridge Complex: 0.17–7.99 g/t Au.
| | | | | | | | |
Date: February, 2022 | | Page 12-3 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 12-2: Input Parameters, Underground (mineral reserves)
| | | | | | | | | | | | | | | | | | | | | | | |
Economic Parameters | Units | Carlin Complex | Cortez Complex | Turquoise Ridge Complex |
Minimum | Maximum | Minimum | Maximum | Minimum | Maximum |
Gold price | US$/oz | 1,200 | 1,200 | 1,200 | 1,200 | 1,200 | 1,200 |
Royalties | % | 0.56 | 6 | 1 | 3 | 1 | 1 |
Discount rate | % | 5 | NA | NA | NA | NA |
Mining cost | US$/t | 61.30 | 145.63 | 76.16 | 97.15 | 132.30 | 213.72 |
G&A cost | US$/t | 9.44 | 15.67 | 10.79 | 15.19 | 5.65 | 17.45 |
Process cost | US$/t | 18.31 | 26.20 | 10.62 | 29.40 | 34.43 | 34.91 |
| % (average) | 82 | 89 | 84 | 89 | 86 | 90 |
Cut-off grades | g/t Au | 3.43 | 7.06 | 3.39 | 5.21 | 3.94 | 7.99 |
Note: Tonnages are metric tonnes.
Revenue from the Phoenix Complex is generated from three products: gold, silver, and copper. A revenue cut-off, rather than a grade cut-off, is used that integrates the economics (recovery, metal prices, and costs) of all three metals. The revenue calculation only includes incremental mining costs beyond the pit rim. The mineral reserves for the Phoenix Complex are reported using a zero-dollar net revenue cut-off.
12.5 Stockpiles
Stockpile estimates were based on mine dispatch data; the grade comes from closely-spaced blasthole sampling and tonnage sourced from truck factors. The stockpile volumes were typically updated based on monthly surveys. The average grade of the stockpiles was adjusted based on the material balance to and from the stockpile.
12.6 Commodity Prices
Commodity prices used in mineral reserve estimation are based on long-term analyst and bank forecasts. An explanation of the derivation of the commodity prices is provided in Chapter 16.2. The estimated timeframe used for the price forecasts is the 24-year LOM.
12.7 Mineral Reserve Statement
Mineral reserves have been classified using the mineral reserve definitions set out in SK1300. Mineral reserves are current as at December 31, 2021. The reference point for the mineral reserve estimate is as delivered to the process facilities. Mineral reserves are reported on a 100% basis. Barrick owns a 61.5% JV interest, with Newmont owning the remaining 38.5% JV interest.
Mineral reserves are reported in Table 12-3 for gold, Table 12-4 for silver, and in Table 12-5 for copper. Tonnages in the table are metric tonnes.
| | | | | | | | |
Date: February, 2022 | | Page 12-4 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
12.8 Uncertainties (Factors) That May Affect the Mineral Reserve Estimate
Areas of uncertainty that may materially impact all of the mineral reserve estimates include:
•Changes to long-term metal price and exchange rate assumptions;
•Changes to metallurgical recovery assumptions;
•Changes to the input assumptions used to derive the mineable shapes applicable to the assumed underground and open pit mining methods used to constrain the estimates;
•Changes to the forecast dilution and mining recovery assumptions;
•Changes to the cut-off values applied to the estimates;
•Variations in geotechnical (including seismicity), hydrogeological and mining method assumptions;
•Changes to environmental, permitting and social license assumptions.
| | | | | | | | |
Date: February, 2022 | | Page 12-5 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 12-3: Proven and Probable Mineral Reserve Statement (Gold)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Deposits | Area | Proven Mineral Reserves | Probable Mineral Reserves | Proven and Probable Mineral Reserves |
Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Au) | Cont. Gold (x 1,000 oz) |
Carlin | Open pit | 15,100 | 2.58 | 1,250 | 79,800 | 1.96 | 5,040 | 94,900 | 2.06 | 6,290 |
Underground | 19,700 | 9.25 | 5,860 | 11,400 | 8.18 | 2,990 | 31,100 | 8.86 | 8,850 |
Stockpiles | 3,500 | 2.58 | 290 | 38,700 | 2.62 | 3,250 | 42,100 | 2.61 | 3,540 |
Carlin sub-total | 38,300 | 6.01 | 7,400 | 129,800 | 2.70 | 11,280 | 168,100 | 3.46 | 18,670 |
Cortez | Open pit | 200 | 1.90 | 10 | 60,700 | 1.66 | 3,240 | 61,000 | 1.66 | 3,250 |
Underground | 1,300 | 8.57 | 350 | 42,200 | 7.77 | 10,540 | 43,500 | 7.79 | 10,890 |
Stockpiles | 2,100 | 2.15 | 140 | — | — | — | 2,100 | 2.15 | 140 |
Cortez Subtotal | 3,500 | 4.43 | 500 | 103,000 | 4.16 | 13,780 | 106,500 | 4.17 | 14,290 |
Long Canyon | Open pit | 300 | 1.43 | 20 | 600 | 1.06 | 20 | 1,000 | 1.18 | 40 |
Long Canyon sub-total | 300 | 1.43 | 20 | 600 | 1.06 | 20 | 1,000 | 1.18 | 40 |
Turquoise Ridge | Open pit | 1,200 | 2.18 | 80 | 13,500 | 1.90 | 820 | 14,600 | 1.92 | 900 |
Underground | 14,300 | 11.05 | 5,060 | 19,200 | 9.89 | 6,090 | 33,400 | 10.39 | 11,160 |
Stockpiles | 27,500 | 2.13 | 1,880 | — | | — | 27,500 | 2.13 | 1,880 |
Turquoise Ridge sub-total | 42,900 | 5.09 | 7,030 | 32,600 | 6.59 | 6,920 | 75,600 | 5.74 | 13,940 |
Phoenix | Open pit | 9,100 | 0.65 | 190 | 155,800 | 0.59 | 2,960 | 164,900 | 0.59 | 3,150 |
Stockpiles | 4,300 | 0.88 | 120 | — | | — | 4,300 | 0.88 | 120 |
Phoenix sub-total | 13,500 | 0.72 | 310 | 155,800 | 0.59 | 2,960 | 169,300 | 0.60 | 3,270 |
NGM Total | Grand Total | 98,500 | 4.82 | 15,260 | 421,800 | 2.58 | 34,960 | 520,300 | 3.00 | 50,220 |
| | | | | | | | |
Date: February, 2022 | | Page 12-6 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 12-4: Proven and Probable Mineral Reserve Statement (Silver)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Deposits | Area | Proven Mineral Reserves | Probable Mineral Reserves | Proven and Probable Mineral Reserves |
Tonnage (x 1,000 t) | Grade (g/t Ag) | Cont. Silver (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Ag) | Cont. Silver (x 1,000 oz) | Tonnage (x 1,000 t) | Grade (g/t Ag) | Cont. Silver (x 1,000 oz) |
Phoenix | Open pit | 9,100 | 6.475 | 1,900 | 155,800 | 6.351 | 31,810 | 164,900 | 6.357 | 33,710 |
Stockpile | 4,300 | 9.345 | 1,300 | — | — | — | 4,300 | 9.345 | 1,300 |
Phoenix sub-total | 13,500 | 7.397 | 3,200 | 155,800 | 6.351 | 31,810 | 169,300 | 6.434 | 35,010 |
NGM Total | Grand Total | 13,500 | 7.397 | 3,200 | 155,800 | 6.351 | 31,810 | 169,300 | 6.434 | 35,010 |
Table 12-5: Proven and Probable Mineral Reserve Statement (Copper)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Deposits | Area | Proven Mineral Reserves | Probable Mineral Reserves | Proven and Probable Mineral Reserves |
Tonnage (x 1,000 t) | Grade (Cu %) | Cont. Copper (M lbs) | Tonnage (x 1,000 t) | Grade (Cu %) | Cont. Copper (M lbs) | Tonnage (x 1,000 t) | Grade (Cu %) | Cont. Copper (M lbs) |
Phoenix | Open pit | 9,600 | 0.16 | 30 | 208,300 | 0.17 | 770 | 217,900 | 0.17 | 800 |
Stockpiles | 8,200 | 0.17 | 30 | — | — | — | 8,200 | 0.17 | 30 |
Phoenix sub-total | 17,800 | 0.17 | 70 | 208,300 | 0.17 | 770 | 226,100 | 0.17 | 830 |
NGM Total | Grand Total | 17,800 | 0.17 | 70 | 208,300 | 0.17 | 770 | 226,100 | 0.17 | 830 |
Notes to Accompany Mineral Reserve Tables:
1.Mineral reserves are current as at December 31, 2021. Mineral reserves are reported using the definitions in SK1300. The Qualified Person responsible for the estimate is Mr. Donald Doe, RM SME, Group Executive, Reserves, a Newmont employee.
2.The point of reference for the estimates is the point of delivery to the process facilities.
3.Mineral reserves are reported for Nevada Gold Mines on a 100% basis. Barrick owns a 61.5% joint venture interest, with Newmont owning the remaining 38.5% joint venture interest.
4.Mineral reserves that will be mined using open pit mining methods are constrained within a designed pit shell. Mineral reserves that will be mined by underground mining methods are constrained within conceptual stope designs. Parameters used are summarized in Table 12-1 and Table 12-2.
5.Tonnages are metric tonnes rounded to the nearest 100,000. Gold and silver grades are rounded to the nearest 0.01 gold grams per tonne. Copper grade is in %. Gold and silver ounces and copper pounds are estimates of metal contained in tonnages and do not include allowances for processing losses. Contained (cont.) gold and silver ounces are reported as troy ounces, rounded to the nearest 10,000. Copper is reported as pounds and rounded to the nearest 10 million pounds. Rounding of tonnes and contained metal content as required by reporting guidelines may result in apparent differences between tonnes, grade and contained metal content. Due to rounding, some cells may show a zero (“0”). Totals may not sum due to rounding.
| | | | | | | | |
Date: February, 2022 | | Page 12-7 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
13.0 MINING METHODS
13.1 Introduction
Open pit mining is conducted using conventional techniques and an Owner-operated conventional truck and shovel fleet. Open pit operations include the following: South Arturo, Goldstrike, Tri-star, Gold Quarry, Cortez, Pipeline, Crossroads, Long Canyon, Phoenix, Vista and Mega.
Underground mining is currently conducted using conventional stoping methods, and conventional mechanized equipment. Underground operations include the following: Leeville, Pete Bajo (Rita-K), Exodus, El Niño, Goldstrike, Cortez Hills, Goldrush (in development), Turquoise Ridge and Vista.
13.2 Geotechnical Considerations
Nevada Operations personnel and external consultants completed geotechnical studies and provided geotechnical recommendations that form the basis for pit designs. Ground control management plans were developed, and are regularly updated.
Designs use defined geotechnical domains together with rock mass quality ratings for the principal lithologies and appropriate design criteria that reflect expected conditions and risk. Geotechnical models are a compilation of information sourced from geotechnical cell mapping, geological mapping, core logging, and supplementary drilling designed to intersect areas of geotechnical interest, material strength, highwall and stope performance, and hydrological data.
13.2.1 Open Pit
Inter-ramp angles vary by deposit and pit wall lithology, as shown in Table 13-1.
The Nevada Operations undertake regular monitoring of pit walls through geotechnical cell mapping, geological structure mapping, groundwater monitoring, bench inspections, slope stability, and slope movement analyses.
13.2.2 Underground
Stope designs included empirical assessments of maximum hydraulic radii and man-entry opening spans to determine maximum lengths, widths, heights and whether the backs or end-walls were to be unsupported or supported. Stope pillars sizes were analyzed to determine the most suitable pillar sizes for the ground conditions and expected mining methods.
All trafficable underground excavations have minimum requirements for ground support installation. The determination of supportable loads is typically based on a dead load analysis which assesses the potential dislodgement height above an excavation as a proportion of the excavation span. For mine drifts the potential dead load failure height is assumed to form an Isosceles wedge with a maximum apex height of ½ of the excavation span.
| | | | | | | | |
Date: February, 2022 | | Page 13-1 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 13-1: Open Pit Slope Angles
| | | | | |
Complex | Inter-Ramp Slope Angle Range (º) |
Carlin | 11–47 |
Cortez | 25–51 |
Phoenix | 30–52 |
Turquoise Ridge | 36–55 |
Long Canyon | 37–52 |
The embedment capacity of rock bolts beyond the assumed failure surface only contributes to the retention force available. Retention forces are designed to exceed driving forces by at least 50% (i.e., a factor of safety of 1.5). The intersection of two mine drifts and the resultant increased span uses a similar design philosophy. For mine intersections the assumed maximum apex height is 1/3 of the excavation span. The design process follows the guidelines proposed by Pakalnis (2015).
Trafficable opening dimensions are specified in each underground site’s Ground Control Standards. These standards are reviewed and approved annually and describe the minimum ground support requirements for each planned excavation type. Excavations that are designed outside of these standards require engineering of a site-specific design.
Mining methods employed at underground site include either cut-and-fill or long-hole open stoping methods, or a combination of the two. The mining method selection is based on the expected ground conditions from either a rock mass classification block model or by reviewing drill core information. All sites have or a working towards developing site specific stability charts that follow the methodology originally proposed by Mathew et al., (1981).
At certain sites, adjustments to mining methods are in process to reflect updated understanding of rock mass conditions.
13.3 Hydrogeological Considerations
The Nevada Operations have hydrological models constructed for key operational areas, used to predict the rate of dewatering and for well-location planning. The models are regularly updated.
In areas where underground operations are in proximity to open pit mines, the water levels are typically well below the pit bottom due to underground dewatering.
Dewatering of aquifers within limestone units is required for many of the mines. Pumping rates are controlled to dewater these aquifers based on pit-floor advance or level advance. In other mines, faults provide segmentation of water-bearing materials. In those instances, hydrological domains that are separated from existing dewatering systems are depressurized using a combination of pumping wells and drains. Perched water can be encountered near fault zones and dykes.
Dewatering wells are established both within and outside of the pits, and undergo regular inspections.
| | | | | | | | |
Date: February, 2022 | | Page 13-2 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
13.4 Operations
13.4.1 Open Pit
Ultimate pit designs were developed based on pit optimization analysis. The pit limits incorporate geotechnical and hydrological recommendations into final high walls and are designed to include ramps and access to haulage routes to waste rock storage facilities (WRSFs) and processing facilities. Some deposits include phased pit designs which are used to sequence the mining operation. Phases are designed to optimize the economics of the operation and/or provide access to selected ore for blending purposes.
Haul road effective widths for two-way travel range from 98–141 ft with a maximum grade of 10%. The design width for an operating two-way haul road was typically 150 ft, and the minimum operating width was generally 100 ft. For single-lane haul roads, a minimum road width of 80 ft could be used for the bottom benches of the pit. Bench heights vary from 20–40 ft, and can be 60 ft where triple-benching is employed.
Blast patterns are laid out according to material type using rock type designations. Ore grade and type control is performed by sampling each blast hole unless mining is within a known waste zone. Ore control boundaries are staked and flagged in the field and delivered to a GPS-based system for each loading unit.
The final open pit layouts for the open pit mining operations are provided in Figure 13-1 to Figure 13-4 (Carlin Complex), Figure 13-5 to Figure 13-7 (Cortez Complex), Figure 13-8 (Long Canyon Complex), Figure 13-9 (Phoenix Complex) and Figure 13-10 to Figure 13-11 (Turquoise Ridge Complex).
13.4.2 Underground
Underground mining is mechanized, using large-scale equipment. The most common mining methods are a combination of cut-and-fill mining variants with cemented rock (CRF) or paste backfill, and long-hole stoping with, depending on ground conditions, either cemented or uncemented backfill (Table 13-2).
In the cut-and-fill stopes, headings are usually cycled using conventional drill/blast/muck/support on a round-by-round basis or by using mechanical cutting (road header). Top-cut headings are typically 15 x 15 ft and undercut widths vary from 18–30 ft, depending on ground conditions and ore geometry, generally with 15 ft heights. Mining may be by successive undercuts parallel to and below the top cut, or the undercuts may be driven at an angle to the top-cut. Undercuts are tight filled with CRF after mining has completed. Once filled, mining may take place in adjacent panels or below.
| | | | | | | | |
Date: February, 2022 | | Page 13-3 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 13-1: Final Mine Layout Plan, South Arturo, Carlin Complex
Note: Figure prepared by NGM, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 13-4 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 13-2: Final Mine Layout Plan, Goldstrike, Carlin Complex
Note: Figure prepared by NGM, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 13-5 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 13-3: Final Mine Layout Plan, Gold Quarry, Carlin Complex
Note: Figure prepared by NGM, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 13-6 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 13-4: Final Mine Layout Plan, Tri-Star, Carlin Complex
Note: Figure prepared by NGM, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 13-7 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 13-5: Final Mine Layout Plan, Cortez Open Pit
Note: Figure prepared by NGM, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 13-8 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 13-6: Final Mine Layout Plan, Pipeline
Note: Figure prepared by NGM, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 13-9 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 13-7: Final Mine Layout Plan, Crossroads
Note: Figure prepared by NGM, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 13-10 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 13-8: Final Mine Layout Plan, Long Canyon, Long Canyon Complex
Note: Figure prepared by NGM, 2022.
| | | | | | | | |
Date: February, 2022 | | Page 13-11 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 13-9: Final Mine Layout Plan, Phoenix, Phoenix Complex
Note: Figure prepared by NGM, 2022.
| | | | | | | | |
Date: February, 2022 | | Page 13-12 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 13-10: Final Mine Layout Plan, Vista, Turquoise Ridge Complex
Note: Figure prepared by NGM, 2022.
| | | | | | | | |
Date: February, 2022 | | Page 13-13 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 13-11: Final Mine Layout Plan, Mega Pit, Turquoise Ridge Complex
Note: Figure prepared by NGM, 2022.
| | | | | | | | |
Date: February, 2022 | | Page 13-14 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 13-2: Underground Mining Methods
| | | | | | | | | | | | | | | | | |
Site | Cut-and-Fill | Long-hole Open Stoping | Cemented Backfill Type |
Underhand | Overhand | Paste | CRF |
Leeville | X | X | X | X | X |
Goldstrike | X | X | X | X | X |
Exodus | | | X | | X |
Pete Bajo | | X | X | | X |
El Niño | X | X | | | X |
Cortez Hills | X | X | X | | X |
Gold Rush | | | X | | X |
Turquoise Ridge | X | X | | | X |
Long-hole stopes can be either transverse or longitudinal, depending on mineralization geometry and ground conditions. If the strike length of the ore is >60 ft, the development is driven to the end and the stope is mined in a retreat fashion in sections that are generally no longer than 60 ft. Each section is mined and filled before the next section is mined. If ground conditions are poor, the long-hole stope section length can be reduced. Transverse long-hole stopes are typically designed at various heights ranging from 35–100 ft, based on the existing and planned sill development levels used in the active mining areas. Stope widths are designed at varying distances, from 20–25 ft, based on the ground conditions. In secondary stopes, the width is dictated by the actual dimensions of the adjacent primary stopes. Development of the secondary sills may be reduced to about 13 ft, leaving a rock “skin” to account for poor quality backfill in the adjacent stopes. The overall stope length is based on the transverse dimension of the ore; however, individual stopes can be limited to approximately 45 ft.
Overhand drift-and-fill, back stoping, and benching may be used, based on ground conditions and the geometry of the ore zones.
Depending on the operation, material is loaded into haul trucks and hauled to surface using declines, or hoisted via shafts.
Backfill is generated by surface paste plants or underground batch plants. Backfill materials can include quarried crushed rock, crushed open pit waste rock, or roaster tailings. Cement powder and fly ash are used as binders.
Ventilation requirements are met using push–pull methods, with the airflow managed by intake and exhaust fans. Air is typically delivered via shafts or declines, ramps and raises, and circulated through a series of working levels, then exhausted via shafts, declines or raises. Mine air coolers can be installed on the mine air intakes, and spray chambers can be provided for mine air cooling and dust removal. Ventilation designs comply with applicable Mine Safety and Health Administration regulations.
Faces are generally sampled as the development advances and the sample grades are used to estimate the mine production grade and to determine the limits of the ore drives. Muck piles are typically sampled by the load-haul-dump (LHD) vehicle operator.
Mobile equipment maintenance shops and service bays are located underground. Service trucks and tractors are used to access remote areas or provide repair and maintenance services away from the maintenance shops.
Radio, telephone, and wireless network communications are used.
| | | | | | | | |
Date: February, 2022 | | Page 13-15 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
The final underground layouts for the underground mining operations are provided in Figure 13-12 to Figure 13-17 (Carlin Complex), Figure 13-18 (Cortez Complex), Figure 13-21 and Figure 13-22 (Turquoise Ridge Complex).
13.5 Production Schedule
Mining rates for the open pit and underground deposits are summarized in Table 13-3 and Table 13-4. The tables also provide the estimated mine life and the last year of projected operations.
13.6 Blasting and Explosives
Explosives are supplied by an explosives contractor. Emulsion or ANFO is used, depending on the blasting conditions, together with various packaged explosives and initiation systems as required. Blast patterns are laid out according to material type. Appropriate powder factors are used to match ore, waste, and overburden types.
13.7 Waste Rock Storage Facilities
The currently active waste rock storage facilities (WRSFs) and the planned WRSF expansions have adequate capacity for the LOM.
The management of waste rock is based on categorizing by waste rock types based on analytical parameters, with additional refining of waste polygons based on geologic interpretation. The Nevada Operations monitor the requirements for waste and capping materials to ensure that the facilities comply with requirements of the various permits and to ensure that acid-generating waste is capped with waste rock with a net neutralizing material.
13.8 Stockpiles
The open pit production schedules have significant variation in ore delivery over time and there is a high proportion of the ore that is stockpiled after mining and before processing. There are several stockpile options, all of which are based upon the grade of material and varying from leach ore to mill ore. Leach material is generally delivered directly to the leach pads.
| | | | | | | | |
Date: February, 2022 | | Page 13-16 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 13-12: Final Mine Layout Plan, El Niño, Carlin Complex
| | | | | | | | |
Date: February, 2022 | | Page 13-17 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 13-13: Final Mine Layout Plan, Goldstrike, Carlin Complex
Note: Figure prepared by NGM, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 13-18 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 13-14: Final Mine Layout Plan, Rita-K, Carlin Complex
Note: Figure prepared by NGM, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 13-19 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 13-15: Final Mine Layout Plan, West Leeville, Turf, Four Corners, Carlin Complex
| | | | | | | | |
Date: February, 2022 | | Page 13-20 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 13-16: Final Mine Layout Plan, Exodus, Carlin Complex
Note: Figure prepared by NGM, 2022.
| | | | | | | | |
Date: February, 2022 | | Page 13-21 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 13-17: Final Mine Layout Plan, Pete Bajo, Carlin Complex
Note: Figure prepared by NGM, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 13-22 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 13-18: Final Mine Layout Plan, Middle Zone, Cortez Hills, Cortez Complex
Note: Figure prepared by NGM, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 13-23 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 13-19: Final Mine Layout Plan, Lower Zone, Cortez Hills, Cortez Complex
Note: Figure prepared by NGM, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 13-24 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 13-20: Final Mine Layout Plan, Goldrush, Cortez Complex
Note: Figure prepared by NGM, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 13-25 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 13-21: Final Mine Layout Plan, Turquoise Ridge Underground, Turquoise Ridge Complex
Note: Figure prepared by NGM, 2021.
| | | | | | | | |
Date: February, 2022 | | Page 13-26 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 13-22: Final Mine Layout Plan, Vista Underground, Turquoise Ridge Complex, Cross-section View
Note: Figure prepared by NGM, 2021.
Table 13-3: Production Plan (2022–2036)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Item | Unit | LOM | 2022 | 2023 | 2024 | 2025 | 2026 | 2027 | 2028 | 2029 | 2030 | 2031 | 2032 | 2033 | 2034 | 2035 | 2036 |
Total ore mined | M tonnes | 577.2 | 31.6 | 35.9 | 72.0 | 58.8 | 78.7 | 68.0 | 49.4 | 34.1 | 32.5 | 30.0 | 25.5 | 14.9 | 4.0 | 3.9 | 3.9 |
Operating waste mined | M tonnes | 1,201.7 | 192.7 | 208.5 | 145.2 | 174.2 | 171.1 | 60.1 | 35.7 | 68.7 | 60.2 | 42.2 | 13.8 | 11.0 | 1.6 | 1.6 | 1.5 |
Note: numbers have been rounded.
| | | | | | | | |
Date: February, 2022 | | Page 13-27 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 13-4: Production Plan (2037–2045)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Item | Unit | 2037 | 2038 | 2039 | 2040 | 2041 | 2042 | 2043 | 2044 | 2045 |
Total ore mined | M tonnes | 3.9 | 3.9 | 3.7 | 3.7 | 3.5 | 3.6 | 1.9 | 1.3 | 0.2 |
Operating waste mined | M tonnes | 1.6 | 1.6 | 1.5 | 1.5 | 1.4 | 1.5 | 0.8 | 0.5 | 0.1 |
Note: numbers have been rounded.
| | | | | | | | |
Date: February, 2022 | | Page 13-28 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
13.9 Equipment
The number of loading and hauling units allocated to each deposit varies depending on the operational needs from the open pit mine plans. The equipment list also includes the auxiliary equipment needed to support mining and the re-handling of the ore from the stockpile pad into the mill feeders.
Underground equipment requirements include large scale LHDs and haulage trucks, jumbos, and auxiliary equipment.
Equipment requirements for the open pit operations for the LOM are summarized in Table 13-5. Table 13-6 summarizes the equipment requirements for the underground operations.
13.10 Personnel
The Nevada Operations currently employ 2,362 persons in the open pit (Table 13-7) and 2,750 persons in the underground mining operations (Table 13-8).
Table 13-5: Open Pit Equipment Requirements
| | | | | | | | |
Complex | Equipment Type | Peak Requirement |
Carlin | Shovel | 6 |
Truck | 60 |
Cortez | Shovel | 8 |
Truck | 74 |
Phoenix | Shovel | 3 |
Truck | 16 |
Turquoise Ridge | Shovel | 2 |
Truck | 11 |
Long Canyon | Shovel | 2 |
Truck | 11 |
| | | | | | | | |
Date: February, 2022 | | Page 13-29 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 13-6: Underground Equipment Requirements
| | | | | | | | |
Complex | Equipment Type | Peak Requirement |
Carlin | Loader | 34 |
Truck | 44 |
Jumbo | 20 |
Bolter | 25 |
Long-hole drill | 11 |
Cortez | Loader | 13 |
Truck | 26 |
Jumbo | 11 |
Bolter | 8 |
Long-hole drill | 6 |
Turquoise Ridge | Loader | 16 |
Truck | 20 |
Jumbo | 6 |
Bolter | 12 |
Long-hole drill | 2 |
Table 13-7: Open Pit Personnel Count
| | | | | |
Complex | Peak Personnel |
Carlin | 905 |
Cortez | 763 |
Phoenix | 288 |
Turquoise Ridge | 243 |
Long Canyon | 163 |
Total | 2,362 |
Table 13-8: Underground Personnel Count
| | | | | |
Complex | Peak Personnel |
Carlin | 1,549 |
Turquoise Ridge | 481 |
Cortez | 720 |
Total | 2,750 |
| | | | | | | | |
Date: February, 2022 | | Page 13-30 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
14.0 RECOVERY METHODS
14.1 Process Method Selection
The designs of the process facilities design were based on a combination of metallurgical testwork, previous study designs, and previous operating experience. The designs are generally conventional to the gold industry.
Metallurgical facilities comprise nine heap leach facilities, two oxide plants, two flotation plants, two autoclave facilities and two roaster facilities (Table 14-1).
14.2 Process Flowsheets
An example schematic showing a typical leach operation is provided in Figure 14-1. The leach operation shown is at the Cortez Complex. Figure 14-2 to Figure 14-8 show simplified flowsheets for each of the mills within the Nevada Operations. Figure 14-9 shows the flowsheet for the Goldstrike autoclave. The flowsheet for the Sage autoclave was included in Figure 14-8. The Goldstrike roaster flowsheet is provided in Figure 14-10.
14.3 Process Facilities
14.3.1 Heap Leach
14.3.1.1 Gold Leach Pads
The basic steps in heap leaching are:
•Run-of-mine or crushed ore are placed onto a prepared surface;
•Gold dissolution is promoted by applying a weak sodium cyanide solution as the lixiviant to the surface of the heap;
•Solution is collected in the leach pad drain system and then pumped to activated carbon columns (CIC) where gold loads onto activated carbon;
•Gold-laden carbon is reclaimed from the CIC circuit and transported to a centralized carbon stripping system where the gold is stripped from the carbon and recovered by electro-winning. Stripped carbon is recycled and reused.
Gold recovery from heap leaching is a function of solution application and management, particle size distribution, time, and mineralogy. Cyanide leach kinetics in the heap leach pads is most strongly affected by ore characteristics.
| | | | | | | | |
Date: February, 2022 | | Page 14-1 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 14-1: Process Facilities
| | | | | | | | |
Process Type | Location | Note |
Autoclaves | Goldstrike autoclave (Carlin) | |
Sage autoclave (Turquoise Ridge)) | |
Roasters | Gold Quarry roaster (Carlin) | Formerly referred to as Mill 6. |
Goldstrike roaster (Carlin) | |
Oxide mills | Juniper (Turquoise Ridge) | |
Cortez oxide mill | |
Flotation facilities | Phoenix | Flotation for copper concentrate followed by carbon-in-leach for gold–silver recovery. |
Gold Quarry concentrator (Carlin) | Formerly referred to as Mill 5. |
Heap leach facilities | Long Canyon | |
Cortez Area 30 | |
Cortez Area 34 | |
Phoenix (copper leach) | |
Twin Creeks L8 (Turquoise Ridge) | |
Twin Creeks L31 (Turquoise Ridge) | |
Carlin South Area Leach (property) | |
Carlin South Area Leach (non-property) | |
Carlin North Area Leach | |
Emigrant (Carlin) | |
| | | | | | | | |
Date: February, 2022 | | Page 14-2 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 14-1: Heap Leach Process Schematic
| | | | | | | | |
Date: February, 2022 | | Page 14-3 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 14-2: Flowsheet, Gold Quarry Concentrator
| | | | | | | | |
Date: February, 2022 | | Page 14-4 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 14-3: Flowsheet, Gold Quarry Roaster
| | | | | | | | |
Date: February, 2022 | | Page 14-5 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 14-4: Flowsheet, Pipeline Mill
| | | | | | | | |
Date: February, 2022 | | Page 14-6 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 14-5: Flowsheet, Phoenix Run-of-Mine Leach
| | | | | | | | |
Date: February, 2022 | | Page 14-7 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 14-6: Flowsheet, Phoenix SX/EW
| | | | | | | | |
Date: February, 2022 | | Page 14-8 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 14-7: Flowsheet, Phoenix Mill
| | | | | | | | |
Date: February, 2022 | | Page 14-9 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 14-8: Flowsheet, Juniper Mill
| | | | | | | | |
Date: February, 2022 | | Page 14-10 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 14-9: Flowsheet, Goldstrike Autoclave
| | | | | | | | |
Date: February, 2022 | | Page 14-11 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 14-10: Flowsheet, Goldstrike Roaster
For oxide leach, run-of-mine material is tracked by pit or royalty source. Tonnage and contained ounces are based upon truck counts, tonnage factors, and the blast hole kriged grade of the material delivered. The tons are adjusted to match the belt-scale weightometers within the crushing circuit for all ore that is crushed. The relative proportions of the sources and royalties of both tons and ounces are conserved, as is the kriged grade. Leach pad inventory is tracked monthly.
14.3.1.2 Copper Leach Pads
Smith Williams Consultants, Inc. (later AMEC and then NewFields) designed the leach pad and ponds for the project. The Phoenix copper leach project constructed a conventional run-of-mine leach pad designed to facilitate the stacking of copper oxide and transition ores as well as the subsequent leaching, solution collection, and pumping. The leach pad design incorporates three phases of construction. Phases I–III have capacities of 49 Mt, 47 Mts, and 40 Mt respectively. The pad construction is in average lift heights of 6.1 m to a maximum height of 91.4 m at a slope of 2.5 horizontal to 1 vertical. The total leach pad area encompasses nearly 162 ha and is a closed-loop system.
| | | | | | | | |
Date: February, 2022 | | Page 14-12 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
The leach pad incorporates a dual liner system, utilizing a low-permeability compacted soil (prepared subgrade) with a coefficient of permeability less than or equal to 1 x 10-6 centimeters per second (cm/s) at 92% of the maximum dry density. A double textured 80-mil high density polyethylene (HDPE) geomembrane overlays the subgrade layer. A protective layer of sand and gravel or silt at a maximum size of 25.4 mm covers the liner, followed by the coarse aggregate drainage layer and solution collection piping. Ten independent solution collection systems allow for operational monitoring of each cell independently of the others. The design also incorporated a process component monitoring system to monitor the leach pad for leaks in the primary liner. The process component monitoring system design helps operations to identify the cell and leach pad phase if a leak occurs.
In addition to the pad, the leach circuit also consists of three ponds: the rich leach solution (PLS)/sediment pond, the Phase I events pond, and the Phase II events pond. A tank within a pond for secondary containment purposes collects the raffinate for distribution to the leach pad. The pond design includes double lining with smooth 80-mil secondary HDPE geomembrane overlain by 80-mil textured primary liner. Each pond has a sloped bottom and a leak collection and recovery system. The Phase II events pond construction will occur with construction of the Phase II leach pad expansion and has sufficient volume to accommodate the Phase III expansion as well. Operating pond design provides the ability to contain the operating volume as well as having approximately 1m of freeboard for un-planned events. The event pond designs accommodate leach pad drain down from an eight-hour power outage or pump loss as well as precipitation from a 100-year/24-hour storm event. The PLS/sediment and Phase I/II event ponds have a total volume of nearly 305 ML.
The raffinate tank is located approximately two miles northeast of the leach pad near the SX/EW facility, and has an operating volume of approximately 1.1 ML. The tank location is approximately 96 m higher in elevation than the toe of leach pad. To capitalize on the elevation difference, the raffinate feed to the leach pad occurs via a level control valve to allow gravity flow to the pad. Recognizing that as the leach pad gets higher it will reach a point where gravity flow is no longer feasible, the raffinate tank design incorporated nozzles and isolation valves to accommodate the future booster pump addition with minimal interruption to operations. The raffinate tank connects to an organic recovery tank so that operations can periodically flood the organic off the surface of the raffinate tank for recovery in the crud and organic treatment system. The raffinate line between the tank and the leach pad is HDPE and runs parallel to the PLS and fresh water lines in a lined secondary containment channel between the leach pad and plant.
The raffinate distributes to the leach pad via drip emitters at a design flow rate of 2,271 m3/hr. The Phoenix ores vary in acid consumption by ore type. Based on testwork, the anticipated average life-of-mine (LOM) acid consumption is approximately 13 kg/t, though early indications from operations suggest long-term consumptions may be less than projected. The pH targets in the raffinate are between 1.5 and 3. Unlike many copper heap leach operations, Phoenix saw no benefit to an acid cure. Higher acid additions only provided opportunities for higher acid consumption.
The design solution application rate is 0.1 L/min/m2). The leach pad operates on a 90-day active leach cycle. Operations allow the area to dry before removing piping and cross-ripping the leach pad to a depth of 3m, readying the area for new ore placement. The rip depth exceeds the 2.4m maximum required to extend beyond the truck-induced compaction zone, which was confirmed with multiple tests conducted on site. The compaction difference between
| | | | | | | | |
Date: February, 2022 | | Page 14-13 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
1.5 m and 2.4 m was negligible, but to ensure adequate long-term percolation at full height, site operations elected to rip the full 3 m depth.
Drain down from the leach pad reports to the PLS/sediment pond. In order to reduce the introduction of fine particulates into the SX plant, the inflow to the PLS pond initially reports to a segregated sediment storage compartment. This allows the fine solids to settle out before the PLS overflows an internal berm into the operating portion of the pond. Four 600 hp vertical turbine pumps transfer the PLS from the pond to the SX plant at an average grade of 0.6 g/L for the LOM. At design flow, there are three operating pumps with one installed spare.
14.3.2 Process Plants
14.3.2.1 Gold Quarry Concentrator (Carlin Complex)
The Gold Quarry concentrator (formerly referred to as Mill 5) relies on oxide pit, oxide stockpile, low-carbonate sulfide material, and high-carbonate sulfide material. The Gold Quarry concentrator uses a combination of flotation and cyanide leaching to recover gold. The basic steps are as follows:
•Crushing and grinding where ore is ground to the appropriate particle size, usually about 65% -200 mesh;
•Conditioning with a mixture of chemicals to provide for air bubble attachment to pyrite, arsenian pyrite, and arsenopyrite particles while minimizing bubble attachment to gangue minerals such as silica or calcite;
•Froth flotation where the pyrite, arsenian pyrite, and arsenopyrite are floated into a concentrate by sparging air into the conditioned slurry;
•Concentrate is thickened and filtered so that it can be further processed through a separate oxidizing facility such as the Gold Quarry roaster or the Sage autoclave;
•Residual gangue or flotation tailings contain sufficient residual gold to warrant CIL processing;
•CIL processing involves leaching of the slurry with cyanide to dissolve the gold and then adsorb the gold onto activated carbon;
•Gold-laden coconut carbon is transported to the carbon stripping facility where the gold is stripped from the carbon and recovered by electro-winning. Stripped carbon is recycled and reused.
Gold recovery from the flotation process is dependent upon the application of the appropriate amount of grinding to liberate the pyrite and enable the sulfide mineral(s) to be selectively floated away from the bulk of the ore. Gold recovery from the CIL process is typically a function of the ease of solution access to gold particles.
Plant throughput is a nominal 15,600 st/day which is below the permitted rate of 36,000 st/day.
| | | | | | | | |
Date: February, 2022 | | Page 14-14 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
14.3.2.2 Pipeline Mill (Cortez Complex)
The Pipeline mill treats material from the Crossroads/Pipeline open pit, Cortez Pits open pit, Cortez Hills underground, and historical stockpiles derived from mining of the Pipeline and Cortez Hills open pits.
The basic steps are as follows:
•Crushing and grinding;
•CIL and CIC circuits;
•Counter-current-decantation wash thickener circuit
•Carbon stripping and reactivation circuits,
•Doré refining.
Plant throughput can reach 18,000 st/d depending on the hardness of the ore being processed. The plant is permitted for an annual average of 5.4 Mst/a.
14.3.2.3 Phoenix SX/EW Plant (Phoenix Complex)
The Phoenix SX/EW plant treats material from the Fortitude and Bonanza open pits.
The SX plant consists of a single train of conventional mixer–settlers. There are two extraction mixer–settlers with a single strip mixer–settler. The settler design provides operational flexibility to run in series (2 + 1) or in parallel (1 + 1 + 1) depending on operating conditions. Each of the extraction mixer–settlers has a single pump mixer followed by secondary and tertiary mixers, all with variable frequency drive (VFD) control. The mixer–settlers, constructed of 316 L stainless steel, are approximately 31 m long by 25 m wide by 1.3 m deep. There are two rows of picket fences, including a chevron fence followed by a straight fence. The strip mixer–settler only includes a primary pump mixer and a secondary mixer, both with VFD control.
The process uses Cytec’s ACORGA M5774 extractant and Chevron Phillips’ Orfom SX-12 diluent. The extractant concentration in the organic is approximately 3.5 volume percent (v/o). Fire mitigation uses a high pressure water mist that rapidly cools the flames and displaces the available oxygen away from the point of combustion while filling the remaining atmosphere with water vapor.
Tank farm design includes standard features such as electrolyte and organic storage tanks, electrolyte dual media filters, and equipment for organic treatment. Because of the extreme temperature variance, there are three boilers installed to ensure adequate electrolyte heating capacity during the winter months. To help minimize the risk of sulfate crystallization, all electrolyte lines and tanks are heat traced and insulated. The electrolyte tanks are also inside a building shell to further reduce the risk. The building also contains a segregated, fire protected room for the organic treatment filter and three phase decanting crud centrifuge.
The electrowinning building houses 30 polymer-concrete EW cells. Each cell contains 60 permanent stainless steel cathodes and 61 lead-calcium-tin anodes. The plant layout allows for future expansion to the north, mirroring the existing plant, to double the EW capacity if necessary. The design average production is 10,886 t/a of copper cathodes. The design current density is 323 A/m2 with a maximum current density of 377 A/m2.
| | | | | | | | |
Date: February, 2022 | | Page 14-15 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Copper electrowinning uses variable reactance transformer (VRT) and silicon controlled rectifier (SCR) technology.
The EW building houses metallurgy, operations, and maintenance personnel offices, the plant control room, a maintenance facility, and training/break room, along with locker room facilities. Next to the control room, the project provided a process/metallurgical laboratory for performing operational control sample analyses and cathode grading. Assaying of composite samples for metallurgical accounting occurs at an offsite lab.
The plant receives concentrated sulfuric acid from the Gold Quarry roaster and from an offsite bulk storage facility. The acid arrives by truck for gravity offload into two bulk storage tanks for leach acid and one small storage tank for electrolyte makeup acid. Diluent is the only other bulk reagent, which also arrives by truck for gravity offload into a site storage tank.
Plant throughput is nominal 28 st/day which is below the permitted rate 33 st/day.
14.3.2.4 Phoenix Mill (Phoenix Complex)
The Phoenix mill treats material from the Fortitude and Bonanza open pits. The plant has a copper/gold specific flotation system designed to provide concentrate products for sale to an outside smelter. The basic steps are as follows:
•Crushing and grinding;
•Adjustment of pH as required;
•Conditioning the slurry using collectors and activators to prevent oxidation of the sulfide mineral surfaces and create hydrophobic conditions;
•Frothing chemicals and air added to the flotation cells creating a liquid/gas interface for the hydrophobic particle to cling to;
•Residual gangue minerals contain sufficient gold for recovery by conventional CIP processing;
•Flotation tails are processed through a sands/slimes separation circuit using Hydrosizers, ahead of the CIL circuit. Most of the gold goes to the sands, and most of the copper goes to the slimes, reducing cyanide consumption in the CIP circuit. Slimes are thickened and sent to the TSF;
•The concentrate is filtered and processed through an outside smelter. The final flotation concentrate contains all of the copper, about 40% of the gold, and 35% of the silver produced by the Phoenix plant.
Gold is also recovered by gravity separation:
•Gravity separation occurs in two circuits, the first in the grinding circuit and the second on the initial rougher float product;
•The primary gravity circuit processes screened SAG and ball mill products;
•The flotation gravity circuit is in two stages, including a second, cleaner stage;
•All gravity concentrates undergo intensive cyanidation, producing a rich solution that joins rich solution from the CIP circuit ahead of electrowinning.
| | | | | | | | |
Date: February, 2022 | | Page 14-16 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
The Phoenix mill treats copper sulfide and gold bearing ores from the Fortitude and Bonanza pits. Plant throughput is a nominal 36,000 st/day which is below the permitted rate of 57,600 st/day.
14.3.2.5 Juniper Mill (Turquoise Ridge Complex)
Run-of-mine higher-grade oxide ore from the Turquoise Ridge Surface sources are blended for gold grade, hardness, and carbonate content and fed to the Juniper oxide mill. Undersize rejects from the Turquoise Ridge Underground aggregate crusher are added when additional carbonate is needed. The process consists of:
•A variable speed 900 Hp SAG mill operating in closed circuit with a discharge screen. The SAG mill product is fed to a 1,150 Hp ball mill operating in closed circuit with cyclones. The final product grind size is 90% - 200 mesh;
•Cyclone overflow product is fed to the neutralization circuit, where the carbonate in the oxide ore is used to neutralize the acidic autoclave discharge slurry. The combined oxide slurry and autoclave discharge slurry are further neutralized with lime before treatment in the CIL circuit;
•The CIL circuit is used to concurrently leach gold from the ore and adsorb it onto activated carbon. The final tailings slurry is pumped to the TSF;
•The gold-loaded carbon is stripped, acid washed, kiln reactivated, and recycled back to the CIL circuit. The gold stripped from the carbon is electrowon and refined into doré for shipment to an offsite refinery.
Plant throughput can reach 120 st/hr depending on the hardness of the ore being processed. This is augmented when limestone is added. The plant is permitted for running 250 st/h or 6,000 st/d.
14.3.3 Autoclaves
14.3.3.1 Goldstrike (Carlin Complex)
The Goldstrike autoclave treats material from Goldstrike Betze Open Pit. The basic steps are as follows:
•Feed is sourced from ore stockpiles located adjacent to the primary crusher;
•A Phase I grinding circuit consists of a jaw crusher, SAG mill operating in closed circuit with a pebble crusher, two secondary ball mills, and a tertiary ball mill operating in closed circuit with cyclones;
•Phase I cyclone overflow feeds two thickeners, providing an ability to operate the grinding circuits separately on alkaline or acid POX feed blends;
•A Phase II grinding circuit consists of a gyratory crusher, SAG mill operating in closed circuit with a pebble crusher;
•The Phase II discharge screen undersize is pumped along with ball mill discharge to a bank of cyclones;
| | | | | | | | |
Date: February, 2022 | | Page 14-17 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
•Grinding circuit thickener underflow when treating an acid ore blend (ore treated with acid) is fed to a series of acidulation tanks where sulfuric acid is added if required to digest carbonate content;
•There are five autoclaves operating in parallel at Goldstrike, all of which are configured for acid POX, while three lines can also be configured for alkaline ore POX;
•The milled, acidified slurry is fed to a series of preheaters where hot steam from the autoclave discharge flash tank is contacted with incoming feed to preheat the slurry and transfer available heat from the oxidation reactions. Pressure oxidation is carried out under elevated pressure and temperature using high purity oxygen in the autoclaves;
•Autoclave discharge progresses through a series of flash vessels with additional cooling accomplished in tube and shell slurry heat exchangers. Autoclave discharge slurry is acidic due to the formation of sulfuric acid from sulfide oxidation reactions;
•Neutralization of autoclave discharge to pH 8.0 is accomplished with slaked lime prior to thiosulfate leaching;
•As carbonate levels in a portion of the ores at Goldstrike have increased, three of the autoclaves (#4, #5, #6) have been converted such that they can operate under alkaline conditions;
•The grinding circuit product is fed to a thickener dedicated to alkaline POX operation. Thickener underflow is directed to the acidulation circuit for storage, but no acid is needed;
•The alkaline slurry reports through a series of slurry coolers to neutralization, where it is adjusted to pH 8.0 with slaked lime and then directed to thiosulfate leaching and resin-in-leach for gold recovery;
•The slurry from the alkaline and acid autoclave circuits is pumped to parallel calcium thiosulfate–resin-in-leach circuits. Cyanide has been replaced with the on-site production of calcium thiosulfate for gold dissolution. The resin is pumped counter-current to the slurry with a portion of new or recycled resin returned directly to the first resin-in-leach tank. From the first tank, loaded resin is transferred to elution and refining for the recovery of gold. The slurry exiting the final tank is sent to a tailings thickener and then pumped to a dedicated TSF to avoid comingling thiosulfate and cyanide solutions;
•Gold-bearing resin is processed in a multi-stage elution circuit. Rich solution containing the gold is forwarded to dedicated electrowinning cells operated within the gold refinery to produce doré bullion which is shipped off site for further refining. The stripped and regenerated resin is returned to the resin-in-leach circuit.
The plant is permitted for an annual average of 1,000 st/operating hour per autoclave limit.
The autoclave is planned to be converted to CIL in 2022–2023 once all of the high alkaline, preg-robbing, low-grade, double refractory stockpiles are depleted.
14.3.3.2 Sage (Turquoise Ridge Complex)
The Sage autoclave treats material from the Turquoise Ridge Underground, Mega open pit, Vista underground, and historical stockpiles derived from mining of the Mega and Vista open pits.
| | | | | | | | |
Date: February, 2022 | | Page 14-18 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
The process consists of:
•SAG milling followed by ball milling;
•Cyclone overflow reports to a thickener. Thickener underflow reports to an acidification circuit where sulfuric acid is added as necessary. Thickener overflow solution is returned to the milling circuit;
•After acidification, ore slurry is added to two identical autoclaves that are operated in parallel. Two stages of flash heat recovery are used. Autoclave discharge is cooled before reporting to the lime neutralization circuit;
•Oxide ore and acidic oxidized sulfide ore slurry are combined in the neutralization circuit;
•After neutralization, the ore slurry reports to a CIL circuit where the ore is leached in cyanide solution to extract the gold. Final tailings slurry is pumped to the TSF;
•Loaded carbon from the CIL circuit is transferred to the recovery plant. After acid washing to remove inorganic contaminants, the carbon is transferred to the pressure Zadra stripping circuit;
•Rich solution from the stripping circuit is pumped to an electrowinning circuit where precious metal is removed and refined into doré bars.
Plant throughput is a nominal 13,900 st/day which is below the permitted rate of 16,800 st/day.
14.3.4 Roasters
14.3.4.1 Goldstrike (Carlin Complex)
The Goldstrike roaster treats open pit and underground material from numerous sources including the South Arturo open pits, El Niño underground, Goldstrike underground, Goldstrike open pit, historical stockpiles derived from mining of the Goldstrike open pit, Goldstar open pit, Leeville underground, Pete Bajo underground, Exodus underground, Cortez Crossroads/Pipeline open pit, Cortez Hills underground, historical stockpiles derived from mining of the Cortez Hills and Crossroads/Pipeline open pits, and Goldrush underground.
The basic steps are as follows:
•Two stages of open circuit crushing including a gyratory crusher, scalping screen and cone crusher;
•Crusher product is sent to one of the two parallel dry grinding circuits. The ore is heated with natural gas and progresses toward the center of the mill as it is being dried and ground where it is transported with air through grates, a static cyclone classifier and a dynamic classifier for size separation;
•Oversize is returned to the second stage of the grinding mill for further size reduction while undersize material is transferred to bag houses for further processing;
•Material from the roaster silo is fed to the top of the roaster by a bucket elevator and a fluidized feeder. The fluidized feeder distributes ore continuously to the first stage (upper) bed of the two parallel roasters;
| | | | | | | | |
Date: February, 2022 | | Page 14-19 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
•Solids flow by gravity to the second stage of the roaster through an inter-stage solid transfer system. High purity oxygen is injected at the bottom of the second stage of the roasters. Oxidation is essentially complete after the second stage;
•A gas circuit removes contaminants;
•The calcine product from the roaster is cooled rapidly in quench tanks. The cooled quench tank discharge from both roasters is combined and the resulting slurry feeds neutralization tanks;
•Neutralization circuit slurry is dewatered in a thickener with excess water recycled for reuse in the quench tanks. The thickener underflow reports to the roaster CIL circuit;
•Slurry flows through the series of CIL tanks. Activated carbon is then transferred to a loaded carbon holding bin and into a truck that transports it for elution, acid washing, and regeneration in a carbon handling circuit located within the Goldstrike autoclave facility.
Plant throughput is a nominal 18,700 st/day which is below the permitted rate of 24,000 st/day.
14.3.4.2 Gold Quarry (Carlin Complex)
The Gold Quarry Roaster treats open pit and underground material from Carlin and Cortez, as well as sulfide concentrates. The process steps at the Gold Quarry Roaster are as follows:
•Crushing and dry grinding;
•Roasting at a high enough temperature to oxidize the sulfide and carbonaceous material, but at a low enough temperature that the gold is not re-encapsulated in microscopic “clinkers”;
•Leaching using a cyanide solution in the slurry in conjunction with oxygen which can be supplied by air-sparging or by the addition of enriched oxygen;
•Magnetic separation is applied to recover gold locked in a magnetic component of the tailings and transported to an autoclave for acidification and cyanide leaching;
•CIL processing involves leaching of the slurry with cyanide to dissolve the gold and then adsorb the gold onto activated carbon;
•Gold-laden coconut carbon is transported to the carbon stripping facility where the gold is stripped from the carbon and recovered by electro-winning. Stripped carbon is recycled and reused.
A cost-saving step is afforded by processing the off-gas from the roaster for recovery of sulfur dioxide as sulfuric acid. Because the final processing steps are the same as in the oxide mill, the performance of a roasting facility is similarly driven by the same parameters with the addition of sufficient retention time in the roaster in contact with sufficient oxygen to complete the oxidizing process.
Plant throughput can reach 13,000 st/d, depending on the hardness of the ore being processed. The plant is permitted for an annual average of 13,440 st/d.
| | | | | | | | |
Date: February, 2022 | | Page 14-20 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
14.4 Equipment Sizing
The major equipment required for the heap leach operations is summarized in Table 14-3, in Table 14-4 for the mill facilities, in Table 14-5 and Table 14-6 for the Phoenix facilities, in Table 14-7 for the autoclaves and in Table 14-2 for the roaster.
14.5 Power and Consumables
14.5.1 Power
Power supplies are discussed in Chapter 15.11.
14.5.2 Consumables
The major consumables in the gold heap leach facilities are antiscalant, cyanide and lime. The copper heap leach pads use sulfuric acid.
The Phoenix SX/EW plant uses sulfuric acid (electrolyte), cobalt, diluent, extractant, diatomaceous earth, clay, and starch.
Mill facilities use grinding media, balls for ball mills, lime, cyanide, collector, frother, and hydrogen peroxide.
The Goldstrike autoclave requires calcium thiosulfate and resin. Both autoclaves use grinding media, balls for ball mills, lime, and cyanide.
Table 14-2: Key Equipment List, Roasters
| | | | | | | | |
Roaster | Equipment Type/Item | Number |
Goldstrike Roaster | Thyssenkrupp Double Rotator, 2x 5.8mx 17.5m, 7355kW | 1 |
Dorr Oliver Roasters 2 stage fluidized bed | 2 |
Gold Quarry Roaster | Double Rotator 6.1m x 25.6m, 11MW | 1 |
CFB Roasters | 2 |
| | | | | | | | |
Date: February, 2022 | | Page 14-21 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 14-3: Key Equipment List, Leach Facilities
| | | | | | | | |
Leach Area | Equipment Type/Item | Number |
South Area Leach (SAL) | Rich solution pumps | 8 |
Spent solution pumps | 3 |
CIC | 21, 18 in operation |
Solution flow | 6,500 gpm |
North Area Leach (NAL) | Rich solution pumps | 4 |
Spent solution pumps | 3 |
CIC | 12 |
Solution flow | 7,000 gpm |
Emigrant Area Leach (EAL) | Rich solution pumps | 3 |
Spent solution pumps | 3 |
CIC | 18, 12 in operation |
Solution flow | 7,500 gpm |
Cortez Leach Area 30 | Pregnant pumps | 6 |
Barren pumps | 5 |
CIC | 20 |
Solution flow | 21,000 gpm, max permit |
Cortez Leach Area 34 | Pregnant pumps | 3 |
Barren pumps | 2 |
CIC | 15 |
Solution flow | 12,600 gpm, max permit |
Table 14-4: Key Equipment List, Mill Facilities
| | | | | | | | | | | |
Area | Item | Description | Capacity |
Cortez Oxide | SAG mill | Allis 26ft x 11 ft | 4500 hp |
Primary ball mill | Allis 16ft x 28.5 ft | 4500 hp |
Juniper | SAG mill | Marcy 18 ft x 6.5 ft | 900 hp |
Primary ball mill | Marcy 11.5 ft x 16.4 ft | 1,150 hp |
| | | | | | | | |
Date: February, 2022 | | Page 14-22 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 14-5: Key Equipment List, Phoenix SX/EW
| | | | | | | | |
Item | Quantity | Source/Vendor |
Mixer tank | 12 | CAID |
Raffinate tank | 1 | GBI |
Mixer | 6 | Lightnin |
Electrolyte tank | 4 | GBI |
Crud centrifuge | 1 | Flottweg |
Electrolyte filter | 1 | SpinTek |
Pre-coat mix tank | 1 | Durco Filters |
Organic filtrate tank | 1 | Durco Filters |
Loaded organic tank | 1 | GBI |
Organic treatment filter feed tank | 1 | CAID |
Anodes | 1830 | Quemetco Metals |
Cathodes | 1800 | CAID |
Electrowinning cell | 30 | CTI/PI Int'l. Inc. |
Cathode strip conveyer | 1 | Mesco/PI Int'l. Inc. |
EW cell hood | 30 | SAME |
Rectifier | 2 | Ametek |
Sulfuric acid leach storage tank | 2 | Contract C002 |
EW acid storage tank | 1 | Great Basin Ind |
Diluent storage tank | 1 | Great Basin Ind |
Guar/starch mix tank | 1 | Solid Technology |
Extraction/ strip settler | 3 | CAID |
Table 14-6: Key Equipment List, Phoenix Mill
| | | | | | | | |
Item | Quantity | Source/Vendor |
60 x 89 primary gyratory crusher | 1 | Fuller Traylor |
50 x 65 primary gyratory crusher | 1 | Metso |
Secondary cone crushers | 2 | Raptor 1100 |
Pebble cone crusher | 1 | Metso MP800 |
36’ x 18’ SAG mill 18,000 hp | 1 | Farnell Thompson |
21’ x 33’ overflow ball mill 9,500 hp | 2 | Farnell Thompson |
KC-48 concentrators | 4 | Knelson |
CS-4000 intensive cyanidation reactor | 1 | Consep Acacia |
160 m3 flotation tank cells | 12 | Dorr-Oliver |
30 m3 flotation tank cells | 8 | Dorr-Oliver |
E-CAT concentrate thickener | 1 | EIMCO |
32 m high rate tailings thickener | 1 | Outokumpu |
Plate and frame filter press | 1 | Lasta |
49.5’ x 54’ agitated leach tanks | 2 | |
36.5’ x 40’ agitated CIP tanks | 5 | |
ADR circuit | 1 | Pressure Zadra |
| | | | | | | | |
Date: February, 2022 | | Page 14-23 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 14-7: Key Equipment List, Goldstrike Autoclave
| | | | | | | | | | | | | | |
Autoclave | Mill Circuit | Item | Size/Quantity | Source/Vendor |
Goldstrike | Mill 1 | Jaw crusher | 300 hp 50 in x 60 in | Telsmith |
SAG mill | 2500 hp 22 ft x 8 ft | Allis Chalmers |
Secondary ball mill | 1,800 hp 13.5ft x 18 ft | Dominion |
1,250 hp 12.5 x 14 ft | Allis Chalmers |
Mill 2 | Gyratory crusher | 400 hp 42 in x 65 in | Allis Chalmers |
Autogenous grind mill | 4,000 hp 24 ft x 12 ft | Fuller |
Secondary ball mill | 5,000 hp 16.5 ft x 30.5 ft | Fuller |
Table 14-8: Key Equipment List, Sage Autoclave
| | | | | | | | |
Item | Description | Capacity |
SAG mill | Koppers 28 ft x 10 ft | 4,000 hp |
Primary ball mill | Svedala 20 ft x 30 ft | 7,500 hp |
Secondary ball mills | 2 x Dominion 16.5 ft x 29 ft | 4,000 hp |
Autoclaves | 16.5 ft x 73.3 ft | 89,500 gal |
Oxygen plant | air products ASU 95% O2 | 1,360 t/d |
The roasters require oxygen, grinding steel, cyanide, lime and sulfur.
14.5.3 Water
Water supply for process operations is discussed in Chapter 15.7.
14.6 Personnel
The LOM average personnel counts for the Nevada Operations are:
•Long Canyon leach: 13;
•Phoenix Mill: 120;
•Phoenix copper leach: 24;
•Goldstrike autoclave: 94;
•Goldstrike roaster: 116;
•Gold Quarry roaster: 212;
•Gold Quarry concentrator: 132;
•Carlin leach: 35;
•Emigrant leach (residual leach, no active mining or mineral reserves): 7;
•Cortez Pipeline oxide mill: 101;
•Cortez leach: 16;
•Sage autoclave/Juniper mill: 113;
•Turquoise Ridge leach: 13.
| | | | | | | | |
Date: February, 2022 | | Page 14-24 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
15.0 INFRASTRUCTURE
15.1 Introduction
Major infrastructure to support mining operations is constructed and operational. This includes:
•Open pits;
•Shafts, hoisting infrastructure, portals, declines, ramps; ventilation systems; backfill plants;
•Heap leach, mill, autoclave and roasting facilities; mine laboratories;
•Stockpiles; waste rock and tailings storage facilities;
•Conveyors and pipelines;
•Access and haul roads;
•Water management and treatment facilities;
•Power station, transmission lines, electrical stations and substations, electrical distribution networks;
•Truck shops, maintenance facilities, warehouses, and administrative facilities/offices;
•Communications, including fiber optic lines and network communications, mine radio networks, leaky-feeder systems;
•Core and sample pulp storage.
Infrastructure layout plans are provided in Figure 15-1 to Figure 15-7.
Additional infrastructure will include:
•Cortez Complex, Goldrush: mine accesses including portals, declines, and inclines; surface dewatering wells and associate pipe and pumping infrastructure; rapid infiltration basins; underground dewatering/pumping infrastructure; backfill plant; ventilation system; electrical distribution network;
•Turquoise Ridge: a third shaft is being excavated at Turquoise Ridge Underground, and will require some additional supporting surface infrastructure.
•The Cut40 open pit will require relocation of some of the existing surface infrastructure.
15.2 Roads and Logistics
The Project is accessed by all-weather road networks as discussed in Chapter 4. Rail and air services are also outlined in Chapter 4.
| | | | | | | | |
Date: February, 2022 | | Page 15-1 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 15-1: Infrastructure Layout Plan, Carlin Complex North Area
| | | | | | | | |
Date: February, 2022 | | Page 15-2 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 15-2: Infrastructure Layout Plan, Carlin Complex South Area
| | | | | | | | |
Date: February, 2022 | | Page 15-3 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 15-3: Infrastructure Layout Plan, Carlin Complex Rain–Emigrant Area
| | | | | | | | |
Date: February, 2022 | | Page 15-4 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 15-4: Infrastructure Layout Plan, Cortez Complex
| | | | | | | | |
Date: February, 2022 | | Page 15-5 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 15-5: Infrastructure Layout Plan, Long Canyon Complex
| | | | | | | | |
Date: February, 2022 | | Page 15-6 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 15-6: Infrastructure Layout Plan, Phoenix Complex
| | | | | | | | |
Date: February, 2022 | | Page 15-7 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 15-7: Infrastructure Layout Plan, Turquoise Ridge Complex
15.3 Stockpiles
Stockpiles are discussed in Chapter 12.5 and Chapter 13.7.
| | | | | | | | |
Date: February, 2022 | | Page 15-8 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
15.4 Leach Pads
There are nine heap leach facilities in the Project area, all of which are actively being leached. There is sufficient capacity in the existing pads and planned pad expansions for LOM planning purposes.
15.5 Waste Rock Storage Facilities
There are 67 WRSFs in the Project area, of which 36 are inactive and undergoing reclamation, and 31 are active. A total of 24 pits are permitted for partial or full waste backfill.
There is sufficient capacity in the existing WRSFs and planned WRSF expansions for LOM planning purposes.
15.6 Tailings Storage Facilities
There are 19 TSFs in the Project area, of which 11 are inactive and undergoing reclamation, and eight are active.
There is sufficient capacity in the active TSFs and planned TSF expansions for LOM planning purposes.
15.7 Water Supply
Water supply for processing operations is sourced, depending on the facility, from well fields, TSF reclaim, storm run-off water, and pit dewatering.
Potable water is provided by permitted water wells and supporting treatment and infrastructure facilities.
The current water sources, assuming similar climate conditions to those experienced by the operations in the past, will be sufficient for the LOM plan.
15.8 Water Management Structures
Water management operations include systems of dewatering wells, water gathering and conveyance facilities, water storage, water use, and various management options for discharge of excess water. Water not used for mining or milling can be pumped to storage reservoirs. Rapid infiltration basins are used to capture storm run-off water to avoid that water coming into contact with mining operations.
The NDEP allows selected complexes within the Nevada Operations, through discharge permits, to discharge groundwater from pumping operations to groundwater by percolation, infiltration, and irrigation.
The current water management practices are expected to be applicable for the LOM plan.
| | | | | | | | |
Date: February, 2022 | | Page 15-9 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
15.9 Built Infrastructure
All key infrastructure to support mining activities contemplated in the LOM plan is in place, or has been included in the capital cost requirements in Chapter 18.
In the Turquoise Ridge complex, a third shaft is being excavated at Turquoise Ridge Underground, and will require some additional supporting surface infrastructure. The Cut40 open pit will require relocation of some of the existing surface infrastructure.
Planned infrastructure that will be required to support the Goldrush project includes:
•Mine accesses including portals, declines, and inclines;
•Surface dewatering wells and associate pipe and pumping infrastructure;
•Rapid infiltration basins;
•Underground dewatering/pumping infrastructure;
•Backfill plant;
•Ventilation system;
•Electrical distribution network.
Within the immediate area of the planned Goldrush mine, minimal surface facilities will be installed to support the underground mining operation. These will be limited to ventilation shafts, dewatering wells, water management infrastructure power lines and all-weather roads to access the paste plant. Additional services such as a dry and major rebuild workshop will be located within the existing Cortez Mine area.
15.10 Camps and Accommodation
There are no accommodation facilities at any of the complexes. Personnel reside in adjacent settlements including Battle Mountain, Carlin, Elko, Golconda, Wells, West Wendover and Winnemucca.
15.11 Power and Electrical
Electrical power for the Carlin, Cortez, Turquoise Ridge, and Phoenix Complexes is obtained via TS Power Plant and from the Western 102 power plant (both of which are owned and operated by NGM) with transmission by NV Energy.
Power for Gold Quarry, Long Canyon, and Goldrush is supplied via the Wells Rural Electric Power Company.
The Western 102 power plant, located approximately 15 miles east of Reno, has the capacity to supply 115 MW of electricity using 14 reciprocating natural gas-fired engines, and also has a 1 MW solar plant.
The TS power plant has a capacity of 215 MW power generation from its original coal-fired process. The plant is currently being converted to using natural gas in support of carbon-reduction objectives.
Power can be purchased on the open market if required.
| | | | | | | | |
Date: February, 2022 | | Page 15-10 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Electrical facilities include multiple main substations, several smaller substations throughout the Project area, and transmission lines.
| | | | | | | | |
Date: February, 2022 | | Page 15-11 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
16.0 MARKET STUDIES AND CONTRACTS
16.1 Markets
NGM has established contracts and buyers for the gold bullion, copper concentrate and copper cathode products from the Nevada Operations, and has an internal marketing group that monitors markets for its key products. Together with public documents and analyst forecasts, these data support that there is a reasonable basis to assume that for the LOM plan, that the key products will be saleable at the assumed commodity pricing.
There are no agency relationships relevant to the marketing strategies used.
Product valuation is included in the economic analysis in Chapter 22, and is based on a combination of the metallurgical recovery, commodity pricing, and consideration of processing charges.
16.2 Commodity Price Forecasts
The operator of NGM, Barrick, sets metal price forecasts by reviewing the LOM for the operations, which is 10+ years, and setting the commodity price for that duration. The guidance is based on a combination of historical and current contract pricing, contract negotiations, knowledge of its key markets from a long operations production record, short-term versus long-term price forecasts prepared by the Barrick’s internal marketing group, public documents, and analyst forecasts when considering the long-term commodity price forecasts.
Higher metal prices are used for the mineral resource estimates to ensure the mineral reserves are a sub-set of, and not constrained by, the mineral resources, in accordance with industry-accepted practice.
The long-term commodity price forecasts are:
Mineral reserves:
•Gold: US$1,200.00/oz;
•Silver: US$16.50/oz;
•Copper: US$2.75/lb;
Mineral resources:
•Gold: US$1,500.00/oz;
•Silver: US$20.50/oz
•Copper: US$3.50/lb.
16.3 Contracts
NGM has contracts in place for the majority of the copper concentrate with smelters and various traders. The terms contained within the sales contract are typical of and consistent with standard industry practice and are like contracts for the supply of copper concentrate throughout the world.
| | | | | | | | |
Date: February, 2022 | | Page 16-1 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
The contracts include industry benchmark terms for metal payables, treatment charges and refining charges for concentrates produced. Depending on the specific contract, the terms for the sale of the Project’s copper concentrate are either annually negotiated, benchmark-based treatment and refining charges, or a combination of annually negotiated terms and price sharing agreements. The differences between the individual contracts are generally in relative quantity of concentrates that are covered under annually-negotiated treatment and refining charges and that are covered under a price sharing formula.
Treatment charges assumed for estimation of mineral reserves are based on the blended rates of the existing contracts through the duration of the agreements. The formula used is sensitive to the underlying copper price and is consistent with long-term expectations for copper treatment and refining charges.
The Phoenix copper leach facility produces cathode copper which is sold to a trader who re-sells for product manufacturing. The terms contained within the sales contract are typical of and consistent with standard industry practice and are like contracts for the supply of copper cathode globally.
NGM’s bullion is sold on the spot market, by marketing experts retained in-house by NGM/Barrick. NGM provides Newmont with the date and number of ounces that will be credited to Newmont’s account, and invoices Newmont for how much NGM is owed, such that Newmont receives credits for the ounces (based on the JV interest) and Newmont pays NGM for the ounces. The terms contained within the sales contracts are typical and consistent with standard industry practice and are similar to contracts for the supply of bullion elsewhere in the world.
The largest in-place contracts other than for product sales cover items such as bulk commodities, operational and technical services, mining and process equipment, and administrative support services. Contracts are negotiated and renewed as needed.
| | | | | | | | |
Date: February, 2022 | | Page 16-2 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
17.0 ENVIRONMENTAL STUDIES, PERMITTING, AND PLANS, NEGOTIATIONS, OR AGREEMENTS WITH LOCAL INDIVIDUALS OR GROUPS
17.1 Introduction
As part of its permitting requirements, NGM has submitted and received approval for numerous PoOs and Reclamation Plans for each area. NGM has additionally submitted and/or provided information to support Environmental Assessments (EA) or Environmental Impact Statements (EIS) for each area containing public lands. The additionally submitted information includes various baseline and supporting studies on various natural resources. These studies include, but are not limited to:
•Vegetation surveys;
•Soil surveys;
•Wildlife surveys:
•Threatened, endangered, and special status species surveys;
•Waters of the US evaluations;
•Waste rock characterization studies;
•Groundwater modelling;
•Pit lake geochemical studies;
•Archaeological surveys;
•Air quality modelling.
Existing operations were reviewed by the BLM and Nevada Division of Environmental Protection Bureau of Mining Regulation and Reclamation (NDEP–BMRR). BLM NEPA analysis under an EA or EIS can result in a Determination of NEPA Adequacy (DNA), Findings of No Significant Impacts (FONSI), or a Record of Decision (ROD). These determinations are issued by the BLM for those operations where PoOs contain public lands.
The PoOs are updated and amended, as necessary, to allow for continuation of mining or additional mine development.
17.2 Baseline and Supporting Studies
17.2.1 Current Operations
NGM manages a number of different environmental aspects during mining operations. The operating PoOs listed in Table 17-1 and/or reclamation areas encompass all of the mining facilities within the Nevada Operations.
These geographic boundaries define areas approved for disturbance by the BLM in the form of DNAs, EAs, and EISs, as well as Nevada State permits under NDEP including water pollution control, air and water quality, reclamation, closure permits, and other permits.
| | | | | | | | |
Date: February, 2022 | | Page 17-1 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
EISs can require the implementation of mitigation plans due to potential identified impacts. Such plans can contain specific actions to be taken to mitigate potential impacts to riparian and wetland areas, springs and seeps, streams and rivers, aquatic habitat and fisheries, threatened, endangered, and candidate species, livestock grazing, terrestrial wildlife, soils, vegetation, visual resources, and recreation and wilderness.
17.2.2 Proposed Operations
The Goldrush project is situated in a culturally- and biologically sensitive area, with numerous cultural sites and within sage grouse habitat.
Major study areas in support of the planned mining operation include air quality, hazardous material and solid waste, noise, waste rock characterization, soils, biological resources, wildlife, special status species, visual and cultural resources, Native American Traditional Values, social and economic values, and environmental justice.
17.3 Environmental Considerations/Monitoring Programs
Each state and federal permit includes monitoring requirements. These requirements can include, but are not limited to:
•Water Pollution Control Permit monitoring of the process facilities to ensure Waters of the State are not compromised (e.g., heap leach pads, TSFs, mills/autoclaves/roaster, and potentially-acid generating WRSFs);
•Surface and groundwater are monitored under various permits to ensure no degradation of the water resource;
•Reclamation and closure activity monitoring to ensure facilities are closed as planned and to prevent environmental degradation;
•Rock blending, isolation, encapsulation and backfilling methods in order to minimize acid generation and leachate migration from waste rock that is potentially acid-generating;
•Monitoring of dewatering and water discharge impacts to ensure regulatory requirements are met;
| | | | | | | | |
Date: February, 2022 | | Page 17-2 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 17-1: Plans of Operations
| | | | | | | | |
Property | PoO Name | BLM Case File |
Carlin | Arturo | NVN-087946 |
Carlin | Bootstrap | NVN-071087 |
Carlin | Carlin | NVN-070574 |
Carlin | Dee | NVN-071216 |
Carlin | Emigrant | NVN-078123 |
Carlin | Genesis-Bluestar | NVN-070712 |
Carlin | Gold Quarry | NVN-070550 |
Carlin | Goldstrike | NVN-070708 |
Carlin | Leeville | NVN-071251 |
Carlin | Rain | NVN-070445 |
Cortez | Cortez | NVN-067575 |
Long Canyon | Long Canyon | NVN-091032 |
Phoenix | Phoenix | NVN-067930 |
Turquoise Ridge Complex | Turquoise Ridge | NVN-64093 |
Turquoise Ridge Complex | Twin Creeks | NVN-064094 |
•Air emissions monitoring, including particulates, NOx, SOx, and mercury where appropriate.
Routine environmental monitoring takes place across the operations, including dust suppression, noise, arsenic, TSF seepage water, leak detection, as well as sample collection of drinking water, ground water, surface water, and monitoring of well water.
Various Water Pollution Control Permits (WPCPs), approved and administered by the NDEP–BMRR, require waste rock to be characterized for PAG and acid neutralizing potential and are reported to the NDEP–BMRR quarterly or semi-annually, as required by the WPCPs. Existing facilities will continue to be managed in accordance with the approved site specific WPCPs and Waste Rock Management Plans. Any new refractory ore stockpiles or WRSFs will be designed, constructed, and monitored in accordance with the guidance received from the NDEP–BMRR.
Refractory ore and waste materials are present at the Phoenix, Turquoise Ridge, Carlin, and Cortez Complexes. Design requirements include encapsulation of potentially acid generating materials inside waste rock facilities and engineered systems for the collection of low pH seepage from waste rock dumps and stockpiles and treatment of the seepage. Stockpile and waste rock permitting are included in Plan of Operations submissions to the BLM and in Water Pollution Control Permit applications to the State of Nevada Division of Environmental Protection.
Tailings are analyzed and reported as part of the WPCP requirements. Tailings impoundments are engineered structures requiring separate approval and strict monitoring and reporting requirements as regulated by the NDEP. The tailings facilities are also closely monitored and inspected for geotechnical stability by the State Division of Water Resources (DWR).
NGM has an integrated ISO 14001 certified environmental management system (EMS) that controls health and safety, and environmental risks. The EMSs are updated on an annual basis and audited every three years. Environmental incidents are noted in a register which forms part of the EMS. Causes and corrective actions are identified, and once completed, the incident is closed out.
These plans will be extended to Goldrush and Robertson as they become operational.
| | | | | | | | |
Date: February, 2022 | | Page 17-3 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
17.4 Closure and Reclamation Considerations
17.4.1 Existing Operations
Initial closure planning is included within all proposals and reclamation plan documents during the permitting process. Closure planning is integrated with mine and reclamation planning to the extent practicable during active operations. Concurrent reclamation of lands as mining progresses is a primary consideration for NGM. Reclamation plans are regularly reviewed and revised at a minimum of every three years to ensure adequate financial assurances have been put in place for required reclamation activities. Approvals are required from both the BLM and NDEP for reclamation and closure plan amendments and bond adjustments.
Various mine facilities are located within the PoO boundaries on both private lands and the federal lands administered by the BLM. Only approved facility disturbance can be constructed within PoO boundaries. All PoO boundaries and private lands within the PoO are under the jurisdiction of the NDEP–BMRR.
The reclamation boundaries define limits of approved disturbance for mining within each PoO boundary. Approved financial assurances cover the reclamation liabilities of facilities associated with mining activity. Agency permit approval is contingent upon the placement of these financial assurances that are held by the Agencies (BLM and/or NDEP) prior to commencement of mining. They are the beneficiaries in the unlikely case that NGM files bankruptcy. Reclamation cost estimates are detailed in the reclamation plans for each plan area and facility. Additional financial assurances, in the form of a trust, may be required for long-term monitoring and maintenance costs estimated to occur after closure (i.e., long-term management of drain-down solution from heap leach pads). A Nevada industry-standard method or Standard Reclamation Cost Estimator (SRCE) model is used by NGM to calculate the liabilities.
In general, reclaimed mine sites must be left safe and stable at a minimum, with removal of all infrastructure and rehabilitation of all landforms. Groundwater quality around tailings storage facilities must meet license conditions.
NGM currently has posted approximately US$2.14 B in financial assurances in the form of letters of credit and surety bonds to cover mine closure costs. Additionally, there are several trusts associated with closure cost planning.
The economic analysis uses a closure cost assumption of US$0.9 B, which is the estimate of actual disturbance.
17.4.2 Proposed Operations
The Goldrush project will require development of a temporary closure plan, a tentative plan for permanent closure/interim closure plan, a plan of operations that includes a reclamation plan and reclamation surety estimate, and a plan for monitoring the post-closure stability of the site.
Additionally, at least two years prior to the initiation of closure, NGM must prepare and submit a final plan for permanent closure under terms of their water pollution control permit (WPCP) and NAC 445A.447. A financial surety must be provided in the form of a performance bond or other instrument suitable to construct, operate, and guarantee completion of reclamation and closure activities. A long-term funding mechanism is anticipated, based on existing mine activities in the
| | | | | | | | |
Date: February, 2022 | | Page 17-4 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Cortez District and elsewhere in the state. The BLM will generally require an estimate of long-term liabilities associated with the holding and monitoring of post-closure mine features. This calculation will include funds for identifiable post-closure contingencies. An estimate for this funding instrument will be developed in consultation with NGM, using existing operations as analogs and adjusting for predicted monitoring requirements.
17.5 Permitting
17.5.1 Existing Permits
All surface activities, including reclamation, comply with all applicable Federal and State laws and regulations. The fundamental requirement, implemented in 43 CFR 3809, is that all hard-rock mining under a PoO or Notice on the public lands must prevent unnecessary or undue degradation to the environment. The PoOs and any modifications to the approved PoOs must also meet the requirement to prevent unnecessary or undue degradation.
Mining of pits and associated disturbances are evaluated and approved by the BLM and the NDEP (Nevada Administrative Code (NAC) Chapter 445A and the Federal regulations 43 CFR 3809). The BLM studies environmental impacts associated with mining under NEPA.
As part of its permitting requirements, NGM has submitted PoOs and Reclamation Plans for each operation. NGM has submitted and/or provided information to support NEPA evaluation for each area containing public lands. The PoOs are updated and amended as necessary to allow for continuation of mining or additional mine development.
Reclamation requirements are regulated by the BLM and NDEP and can include items such as regrading waste rock disposal facilities and heap leach pads, removing and demolishing buildings and structures, regrading disturbed areas, removing and regrading stockpile areas, replacing salvaged growth media, revegetation, diversion and sediment control monitoring, and management of drain down from process facilities (e.g., heap leach pads and tailings). To the extent practicable, NGM attempts to perform reclamation concurrently with mining operations.
Permits pertain to environmental and safety obligations by mining companies, and for day-to-day operations compliance. These compliance permits cover areas such as air quality, surface and ground water quality, wastewater treatment, tailings storage, hazardous materials storage, land reclamation, and community relations. NGM also maintains a legal obligation register to track permitting and ensure on-going compliance. Permit applications and renewals are undertaken as required.
The Nevada Operations have the required permits to operate or will be applying for the permits as they are required for mine development.
As at 31 December, 2021, all material permits for the current operations were in compliance or were in the renewal process.
17.5.2 Additional Permits
The Goldrush project will need the permits and authorizations outlined in Table 17-2. This table assumes off-site transport of ore for processing at Goldstrike and Gold Quarry.
| | | | | | | | |
Date: February, 2022 | | Page 17-5 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Goldrush is going through NEPA review. This will result in completion of an Environmental Impact Statement which will be followed by Record of Decision from the BLM. The start of the NEPA process is completion of baseline studies and submission of a PoO to the BLM.
17.6 Social Considerations, Plans, Negotiations and Agreements
17.6.1 Current Operations
Nevada Gold Mines is one of the largest direct employers in the area and also generates significant indirect employment. Prior to the formation of NGM, Barrick had a robust community relations and social performance strategy and a dedicated team to execute on that strategy. This has continued under NGM. Stakeholder engagement is a primary pillar of that strategy and includes participation in local civic activities; city/town council and county commission meetings; serving on boards and committees; town hall meetings; and one-to-one engagement. From this engagement, NGM listens to, and partners with, local organizations to identify a social investment strategy. Education, health, economic development and cultural heritage are key areas for community investments. NGM has also partnered with local law enforcement on public safety initiatives and conservation groups on environmental conservation programs.
As part of the community affairs program, NGM engages with 10 tribal communities. Prior to the formation of NGM, Barrick worked with eight Western Shoshone communities, but the operational footprint of NGM includes traditional territories of two additional tribes, the Confederated Tribes of the Goshute Reservation and Ft. McDermitt Paiute and Shoshone Tribe. NGM initiated engagement with these two communities when the joint venture was formed. Engagement with partner tribes includes regularly-held meetings called “Dialogue Meetings”; tribal council meetings; community committees; one-to-one engagements and sponsorship of several community-driven initiatives. Through this engagement, NGM works with tribal councils to identify and support community priorities in programs aimed at improving community health and well-being, education attainment, cultural heritage preservation, and economic development.
| | | | | | | | |
Date: February, 2022 | | Page 17-6 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 17-2: Major Permits and Approvals, Goldrush
| | | | | |
Permit or Approval | Granting Agency |
Plan of Operations, EIS ROD | U.S. Department of the Interior, BLM |
Reclamation Permit | NDEP-BMRR |
Historic Properties Treatment Plan (HPTP) | BLM and State Historic Preservation Office (SHPO) |
Explosives Permit | U.S. Department of the Treasury, Bureau of Alcohol, Tobacco, and Firearms |
Review of jurisdictional determinations for CWA Section 404 permitting | US Army Corps of Engineers (USACE), Environmental Protection Agency (EPA) |
Surface Disturbance Permit Class II Operating Permit | Nevada (NV) Department of Conservation and Natural Resources (NV DCNR), NDEP, Bureau of Air Pollution Control, EPA |
WPCPs | NV DCNR, NDEP, BMRR |
Approval to dispose of solid waste authorized at Cortez Sanitary Landfill (Class III Waiver) | NV DCNR, NDEP, Bureau of Waste Management |
EPA Identification Number from Cortez Mine will be utilized | NV DCNR, NDEP, Bureau of Waste Management |
General Discharge Permit (stormwater) | NDEP, Bureau of Water Pollution Control |
Permit to Operate, NRS 519A.250 | Nevada State Minerals Commission, Division of Minerals |
Status and production of all mining and exploration projects, NRS 519A.260 | Nevada State Minerals Commission, Division of Minerals |
USFWS Avian Protection Plan/Take Permit | USFWS |
Working in Waters Permit | NV DCNR, NDEP, Bureau of Water Pollution Control |
Water Rights Change in Point of Use and Point of Diversion, new appropriations | NV DCNR, NDWR |
Hazardous Materials Permit | NV Department of Public Safety-NV State Fire Marshall |
Liquefied Petroleum Gas | NV Board for the Regulation of Liquefied Petroleum Gas |
Solid and Universal Waste Management (batteries, electric fluorescent lamps) | NV DCNR, NDEP, Bureau of Waste Management |
Develop Obligation Register | Internal NGM Requirement |
17.6.2 Proposed Operations
The Cortez Complex, including the Goldrush project, operate on lands traditionally used by the Western Shoshone tribes and bands, and NGM makes efforts to demonstrate respect for indigenous cultural resources, environmental stewardship, and shared benefits to receive support from Western Shoshone communities. These efforts are reflected in the 2014 Collaborative Agreement between Barrick and the Western Shoshone tribes and bands, and the 2018 Programmatic Agreement governing the consultation process for exploration and mining activities potentially impacting cultural or historic resources. NGM’s Community Relations Department has organized a number of tours for members of the Western Shoshone Cultural Advisory Group and the Battle Mountain Band Tribal Elders, along with elected officials, to visit the Goldrush portals. Updates on the project are also provided at the Western Shoshone quarterly dialogue meetings. NGM’s Community Relations Department and Cortez District Management have regular meetings with the community of Pine Valley, Lander, Eureka and Humboldt County Commissioners and Crescent Valley Town Advisory Board to provide project updates.
| | | | | | | | |
Date: February, 2022 | | Page 17-7 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
As the Goldrush project develops, NGM will hold public meetings (and advertise a local grievance mechanism according to the Grievance Management Procedure) if internal strategy deems appropriate so that citizens in the surrounding areas may come to learn more about the project and express their support or concerns. NGM may also share employment growth projections with local government and organizations if needed for local planning purposes.
17.7 Qualified Person’s Opinion on Adequacy of Current Plans to Address Issues
Based on the information provided to the QP by NGM (see Chapter 25), there are no material issues known to the QP. The Nevada Operations are mature mining operations and currently has the social license to operate within its local communities.
| | | | | | | | |
Date: February, 2022 | | Page 17-8 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
18.0 CAPITAL AND OPERATING COSTS
18.1 Introduction
Capital and operating cost estimates are at a minimum at a pre-feasibility level of confidence, having an accuracy level of ±25% and a contingency range not exceeding 15%.
18.2 Capital Cost Estimates
18.2.1 Basis of Estimate
Capital costs are based on recent prices or operating data.
Capital costs include funding for infrastructure, pit dewatering, development drilling, and permitting as well as miscellaneous expenditures required to maintain production.
Mobile equipment re-build/replacement schedules and fixed asset replacement and refurbishment schedules are included.
Sustaining capital costs reflect current price trends.
18.2.2 Capital Cost Estimate Summary
The overall capital cost estimate for the LOM is US$2.6 B, as summarized in Table 18-1.
18.3 Operating Cost Estimates
18.3.1 Basis of Estimate
Operating costs are based on actual costs seen during operations and are projected through the LOM plan.
Historical costs are used as the basis for operating cost forecasts for supplies and services unless there are new contract terms for these items.
Labor and energy costs are based on budgeted rates applied to headcounts and energy consumption estimates.
18.3.2 Operating Cost Estimate Summary
Operating costs for the Nevada Operations are estimated at US$34.9 B, as summarized in Table 18-2.
| | | | | | | | |
Date: February, 2022 | | Page 18-1 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 18-1: Capital Cost Estimate
| | | | | | | | |
Area | Unit | Value |
Mine | US$ B | 1.3 |
Process | US$ B | 0.8 |
General and administrative | US$ B | 0.2 |
Goldrush pre-production | US$ B | 0.4 |
Total | US$ B | 2.6 |
Note: Numbers have been rounded; totals may not sum due to rounding.
Table 18-2: Operating Cost Estimate
| | | | | | | | |
Item | Units | Value |
Mining | US$B | 18.6 |
Rehandle | US$B | 0.8 |
Autoclaves | US$B | 4.8 |
Roasters | US$B | 5.2 |
Oxide Mill | US$B | 0.4 |
Leach | US$B | 0.6 |
G&A | US$B | 3.3 |
Transport | US$B | 1.1 |
Total | US$B | 34.9 |
Note: Numbers have been rounded; totals may not sum due to rounding.
Average operating costs over the LOM include:
•Mining (open pit and underground): US$10.47/t mined;
•Autoclave costs: US$34.01/t processed;
•Roaster costs: US$24.12/t processed;
•Oxide mill costs: US$10.46/t processed;
•Heap leach costs: US$3.53/t processed;
•General and administrative costs (inclusive of transport costs): US$5.78/t processed.
| | | | | | | | |
Date: February, 2022 | | Page 18-2 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
19.0 ECONOMIC ANALYSIS
19.1 Methodology Used
The financial model that supports the mineral reserve declaration is a standalone model that calculates annual cashflows based on scheduled ore production, assumed processing recoveries, metal sale prices, projected operating and capital costs and estimated taxes.
The financial analysis is based on an after-tax discount rate of 5%. All costs and prices are in unescalated “real” dollars. The currency used to document the cashflow is US$.
All costs are based on the 2022 budget. Revenue is calculated from the recoverable metals and long-term metal price and exchange rate forecasts.
19.2 Financial Model Parameters
The economic analysis is based on the metallurgical recovery predictions in Chapter 10.4, the mineral reserve estimates in Chapter 13, the mine plan discussed in Chapter 14, the commodity price forecasts in Chapter 16, closure cost estimates in Chapter 17.4, and the capital and operating costs outlined in Chapter 18. Royalties were summarized in Chapter 3.9.
Taxes assume a rate of 21%, the Nevada Net Proceeds Tax of 5%, and the Nevada Mining Education Tax (see Chapter 3.2.4).
The economic analysis is based on 100% equity financing and is reported on a 100% project ownership basis. The economic analysis assumes constant prices with no inflationary adjustments. Barrick owns a 61.5% JV interest, with Newmont owning the remaining 38.5% JV interest.
Within the NGM JV, copper sales are generally in the form of concentrate, which is sold to smelters for further treatment and refining, and cathode. Copper is sold in either concentrate or cathode form. These sales are to third party customers. Generally, if a secondary metal expected to be mined is significant to the NGM JV, co-product accounting is applied. When the NGM JV applies co-product accounting at an operation, revenue is recognized for each co-product metal sold, and shared costs applicable to sales are allocated based on the relative sales values of the co-product metals produced. Generally, if a secondary metal expected to be mined is not significant to the Joint Venture, by-product accounting is applied. As copper and silver production at each of the NGM operations is not significant to the NGM JV, production from copper and silver are accounted for as by-product sales. Revenues from by-product sales are credited by NGM and Barrick as a by-product credit.
For the purposes of showing a complete cashflow analysis for the Nevada Operations as a whole, silver was treated as a by-product credit.
19.3 Economic Analysis
The NPV5% is US$4.2 B. Due to the profile of the cashflow, considerations of payback and internal rate of return are not relevant.
A summary of the financial results is provided in Table 19-1. An annualized cashflow statement is provided in Table 19-2 to Table 19-4. In these tables, EBITDA = earnings before interest,
| | | | | | | | |
Date: February, 2022 | | Page 19-1 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
taxes, depreciation and amortization. The active mining operation ceases in 2045. Closure costs are estimated to 2045.
19.4 Sensitivity Analysis
The sensitivity of the Project to changes in metal prices, grade, sustaining capital costs and operating cost assumptions was tested using a range of 20% above and below the base case values (Figure 19-1).
The Project is most sensitive to changes in the metal price, followed by operating cost changes and the least sensitive to capital cost changes. Grade is not shown, as the grade sensitivity mirrors the metal price sensitivity.
Table 19-1: Cashflow Summary Table (100% basis)
| | | | | | | | |
Item | Unit | Value |
Metal prices |
Gold | US$/oz | 1,200 |
Copper | US$/lb | 2.75 |
Silver | US$/oz | 16.5 |
Total ore |
Gold tonnage | M | 520 |
Gold grade | g/t | 3.00 |
Copper tonnage | Mt | 226 |
Copper grade | % | 0.17 |
Silver tonnage | Mt | 169 |
Silver grade | g/t | 6.43 |
Gold ounces | Moz | 50 |
Copper pounds | Blb | 0.80 |
Silver ounces | Moz | 35 |
Capital costs | US$B | 2.6 |
Operating cashflow | US$B | 34.2 |
Discount rate | % | 5 |
Free cashflow | US$B | 5.9 |
Net present value | US$B | 4.2 |
Note: Numbers have been rounded; totals may not sum due to rounding. Tonnes are metric tonnes. Barrick owns a 61.5% JV interest, with Newmont owning the remaining 38.5% JV interest. Table 19-1 contains “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, which are intended to be covered by the safe harbor created by such sections and other applicable laws. Please refer to the note regarding forward-looking information at the front of the Report. The cashflow is only intended to demonstrate the financial viability of the Project. Investors are cautioned that the above is based on a high-level mine plan and certain assumptions which may differ from Newmont’s long-term outlook or actual financial results, including, but not limited to commodity prices, escalation assumptions and other technical inputs. For example, Table 19-1 uses the price assumptions stated in the table, including a gold commodity price assumption of US$1,200/oz, which varies significantly from current gold prices and the assumptions that Newmont uses for its long-term guidance. Please be reminded that significant variation of metal prices, costs and other key assumptions may require modifications to mine plans, models, and prospects.
| | | | | | | | |
Date: February, 2022 | | Page 19-2 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 19-2: Annualized Cashflow (2022–2030; 100% basis)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| Units | LOM | 2022 | 2023 | 2024 | 2025 | 2026 | 2027 | 2028 | 2029 | 2030 |
Total ore mined | Mt | 577.2 | 31.6 | 35.9 | 72.0 | 58.8 | 78.7 | 68.0 | 49.4 | 34.1 | 32.5 |
Waste mined | Mt | 1,201.7 | 192.7 | 208.5 | 145.2 | 174.2 | 171.1 | 60.1 | 35.7 | 68.7 | 60.2 |
Ore tonnes treated | Mt | 577.2 | 31.6 | 35.9 | 72.0 | 58.8 | 78.7 | 68.0 | 49.4 | 34.1 | 32.5 |
Contained gold | Moz | 50.2 | 3.8 | 3.3 | 4.6 | 3.9 | 3.7 | 3.6 | 3.1 | 2.9 | 2.4 |
Contained copper | Mlb | 830.0 | 50.6 | 50.5 | 62.6 | 83.7 | 89.2 | 78.7 | 71.3 | 66.5 | 65.1 |
Revenue | $B | 48.4 | 3.6 | 3.1 | 4.1 | 3.6 | 3.5 | 3.6 | 3.1 | 2.8 | 2.2 |
Costs applicable to sales | $B | -34.9 | -2.2 | -2.4 | -2.6 | -2.7 | -3.0 | -2.6 | -1.8 | -1.9 | -1.9 |
Other expenses | $B | -1.9 | -0.1 | -0.1 | -0.2 | -0.1 | -0.1 | -0.1 | -0.1 | -0.1 | -0.1 |
EBITDA | $B | 11.6 | 1.2 | 0.6 | 1.3 | 0.8 | 0.3 | 0.9 | 1.2 | 0.8 | 0.2 |
Operating cashflow (after estimated taxes and other adjustments) | $B | 8.5 | 0.9 | 0.5 | 1.0 | 0.7 | 0.3 | 0.7 | 1.0 | 0.6 | 0.2 |
Total capital | $B | -2.6 | -0.4 | -0.4 | -0.4 | -0.2 | -0.3 | -0.2 | -0.1 | -0.1 | -0.1 |
Free cashflow | $B | 5.9 | 0.5 | 0.1 | 0.7 | 0.4 | 0.0 | 0.5 | 0.8 | 0.5 | 0.0 |
Table 19-3: Annualized Cashflow (2031–2040; 100% basis)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| Units | 2031 | 2032 | 2033 | 2034 | 2035 | 2036 | 2037 | 2038 | 2039 | 2040 |
Total ore mined | Mt | 30.0 | 25.5 | 14.9 | 4.0 | 3.9 | 3.9 | 3.9 | 3.9 | 3.7 | 3.7 |
Waste mined | Mt | 42.2 | 13.8 | 11.0 | 1.6 | 1.6 | 1.5 | 1.6 | 1.6 | 1.5 | 1.5 |
Ore tonnes treated | Mt | 30.0 | 25.5 | 14.9 | 4.0 | 3.9 | 3.9 | 3.9 | 3.9 | 3.7 | 3.7 |
Contained gold | Moz | 2.0 | 2.1 | 1.7 | 1.4 | 1.4 | 1.3 | 1.1 | 1.2 | 1.3 | 1.2 |
Contained copper | Mlb | 56.4 | 55.2 | 52.8 | 47.5 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
Revenue | $B | 2.1 | 2.0 | 1.6 | 1.3 | 1.3 | 1.3 | 1.2 | 1.3 | 1.3 | 1.3 |
Costs applicable to sales | $B | -1.8 | -1.8 | -1.3 | -0.9 | -0.9 | -0.8 | -0.9 | -0.9 | -0.9 | -0.8 |
Other expenses | $B | -0.1 | -0.1 | -0.1 | -0.1 | -0.1 | -0.1 | 0.0 | -0.1 | -0.1 | -0.1 |
EBITDA | $B | 0.1 | 0.2 | 0.2 | 0.4 | 0.4 | 0.4 | 0.3 | 0.3 | 0.4 | 0.4 |
Operating cashflow (after estimated taxes and other adjustments) | $B | 0.1 | 0.2 | 0.2 | 0.3 | 0.3 | 0.3 | 0.2 | 0.3 | 0.3 | 0.3 |
Total capital | $B | -0.1 | -0.1 | -0.1 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
Free cashflow | $B | 0.0 | 0.1 | 0.1 | 0.3 | 0.3 | 0.3 | 0.2 | 0.3 | 0.3 | 0.3 |
| | | | | | | | |
Date: February, 2022 | | Page 19-3 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Table 19-4: Annualized Cashflow (2041–2046; 100% basis)
| | | | | | | | | | | | | | | | | | | | | | | |
| Units | 2041 | 2042 | 2043 | 2044 | 2045 | 2046 |
Total ore mined | Mt | 3.5 | 3.6 | 5.5 | 5.5 | 0.8 | 0.0 |
Waste mined | Mt | 1.4 | 1.5 | 2.2 | 2.2 | 0.3 | 0.0 |
Ore tonnes treated | Mt | 3.5 | 3.6 | 5.5 | 5.5 | 0.8 | 0.0 |
Contained gold | Moz | 1.3 | 1.3 | 0.9 | 0.6 | 0.1 | 0.0 |
Contained copper | Mlb | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
Revenue | $B | 1.3 | 1.3 | 0.9 | 0.6 | 0.1 | 0.0 |
Costs applicable to sales | $B | -0.8 | -0.8 | -0.6 | -0.5 | -0.2 | 0.0 |
Other expenses | $B | -0.1 | -0.1 | 0.0 | 0.0 | 0.0 | 0.0 |
EBITDA | $B | 0.4 | 0.4 | 0.2 | 0.1 | -0.1 | 0.0 |
Operating cashflow (after estimated taxes and other adjustments) | $B | 0.4 | 0.4 | 0.2 | 0.1 | -0.1 | -0.9 |
Total capital | $B | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
Free cashflow | $B | 0.4 | 0.3 | 0.2 | 0.0 | -0.1 | -0.9 |
Note: Numbers have been rounded; totals may not sum due to rounding. Tonnes are metric tonnes. EBITDA = earnings before interest, taxes, depreciation and amortization. Barrick owns a 61.5% JV interest, with Newmont owning the remaining 38.5% JV interest. Table 19-2 contains “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, which are intended to be covered by the safe harbor created by such sections and other applicable laws. Please refer to the note regarding forward-looking information at the front of the Report. The cashflow is only intended to demonstrate the financial viability of the Project. Investors are cautioned that the above is based on a high-level mine plan and certain assumptions which may differ from Newmont’s long-term outlook or actual financial results, including, but not limited to commodity prices, escalation assumptions and other technical inputs. For example, Table 19-2 uses the price assumptions stated in the table, including a gold commodity price assumption of US$1,200/oz, which varies significantly from current gold prices and the assumptions that Newmont uses for its long-term guidance. Please be reminded that significant variation of metal prices, costs and other key assumptions may require modifications to mine plans, models, and prospects.
| | | | | | | | |
Date: February, 2022 | | Page 19-4 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Figure 19-1: NPV Sensitivity
Note: Figure prepared by Newmont, 2021. NPV = net present value.
| | | | | | | | |
Date: February, 2022 | | Page 19-5 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
20.0 ADJACENT PROPERTIES
This Chapter is not relevant to this Report.
| | | | | | | | |
Date: February, 2022 | | Page 20-1 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
21.0 OTHER RELEVANT DATA AND INFORMATION
This Chapter is not relevant to this Report.
| | | | | | | | |
Date: February, 2022 | | Page 21-1 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
22.0 INTERPRETATION AND CONCLUSIONS
22.1 Introduction
The QP notes the following interpretations and conclusions, based on the review of data available for this Report.
22.2 Property Setting
The Nevada Operations are located in a portion of Nevada State that has seen mining activities for over 100 years, and modern-scale operations since the 1960s. As a result, local and regional infrastructure and the supply of goods available to support mining operations is well-established. Personnel with experience in mining-related activities are available in the district. There are excellent transportation routes that access northern Nevada.
There are no significant topographic or physiographic issues that would affect the Nevada Operations. Vegetation is typically sparse. The most common current land use is for livestock grazing.
Mining operations are conducted year-round.
22.3 Ownership
NGM is a JV between Barrick and Newmont. Barrick is the JV operator and has a 61.5% interest, with Newmont owning the remaining 38.5% interest.
22.4 Mineral Tenure, Surface Rights, Water Rights, Royalties and Agreements
The Nevada Operations currently includes 15 operations PoOs and eight exploration PoOs. The area includes private land (surface and minerals) owned or controlled by NGM, and land owned by the federal government that is administered by the BLM.
NGM provided a claims list, fee property list, and location plans for the PoOs. The areas in the claims tables reflect the staked claim area; the areas have not been modified for claim overlaps. In some instances, where the same claims are reported within two or more PoOs; the claims are included in the claims list for the individual PoO for completeness, but have been removed for area and claim number totaling purposes.
Within the operations PoO areas are 9,205 lode, millsite, placer and patented claims covering an area of approximately 163,214 acres. Within the exploration PoO areas are 2,180 lode, millsite, placer and patented claims covering an area of approximately 43,364 acres. Between the operations and the exploration PoOs, NGM holds a total of 11,385 claims covering an area of approximately 206,578 acres.
In addition, NGM holds a number of fee properties, within the operations and exploration PoOs. Collectively, these cover an area of approximately 78,620 acres.
On 11 March, 2019, Barrick and Newmont announced the formation of the NGM JV. Newmont, Barrick, and their respective affiliates that held properties in the AOI contributed to NGM the
| | | | | | | | |
Date: February, 2022 | | Page 22-1 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
respective rights, titles and interests in, to, or under, all properties located in the AOI and any other assets, properties or rights located in Nevada. Newmont and Barrick excluded certain development and exploration properties that the companies held within the AOI from the JV; these included Newmont’s Fiberline and Mike projects, and Barrick’s Fourmile project. The JV has a mechanism for the potential contribution of the excluded properties to NGM in the future.
A number of agreements exist with federal, state, and third-party entities and these are monitored using a land management database.
NGM holds all necessary surface rights for the current mining operations. Additional surface rights will be required to support the Goldrush project envisaged in the LOM plan in this Report.
NGM currently maintains a combination of approximately 1,250 active surface and groundwater rights within 38 hydrographic basins. NGM holds all necessary water rights for the LOM plan envisaged in this Report.
There are numerous royalties that pertain to the active mines within the Nevada Operations. Royalty payments vary, as the payments depend upon actual tonnages mined, the amount of gold recovered from that mined material, the deposit being mined, the receiving entity, and the type of royalty. Active royalty payments are included in the LOM economic analysis.
22.5 Geology and Mineralization
The deposits that comprise the Nevada Operations are considered to be examples of Carlin-style carbonate-hosted disseminated gold–silver deposits and intrusion-related gold–copper–silver skarn deposits.
The geological understanding of the settings, lithologies, and structural and alteration controls on mineralization in the different zones is sufficient to support estimation of mineral resources and mineral reserves. The geological knowledge of the area is also considered sufficiently acceptable to reliably inform mine planning.
The mineralization style and setting are well understood and can support declaration of mineral resources and mineral reserves.
Exploration potential exists adjacent to many of the deposits, along strike and at depth along favorable mineralized structures and within the favorable host lithologies. NGM continues to actively explore in the immediate and near-mine areas.
Multiple opportunities exist in the district to expand known deposits and discover additional mineralization.
22.6 History
The Nevada Operations have over 55 years of active mining history, with modern mining operations commencing in 1965. Modern exploration activity by Newmont and Barrick and their predecessor companies, commenced in the late 1950s.
22.7 Exploration, Drilling, and Sampling
The exploration programs completed to date are appropriate for the style of the mineralization within the Nevada Operations area.
| | | | | | | | |
Date: February, 2022 | | Page 22-2 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Drill holes are oriented with an inclination to accommodate the steeply-dipping nature of the Ahafo deposits, resulting in an intersection generally representing 75–85% of true width. Drilling is orientated generally perpendicular to the strike of the orebodies. Local variations may be present to accommodate infrastructure constraints.
Sampling methods, sample preparation, analysis and security conducted prior to Newmont’s interest in the operations were in accordance with exploration practices and industry standards at the time the information was collected. Current NGM sampling methods are acceptable for mineral resource and mineral reserve estimation. Sample preparation, analysis and security for the NGM programs are currently performed in accordance with general industry standards.
The quantity and quality of the lithological, geotechnical, collar and down-hole survey data collected during the exploration and delineation drilling programs are sufficient to support mineral resource and mineral reserve estimation. The collected sample data adequately reflect deposit dimensions, true widths of mineralization, and the style of the deposits. Sampling is representative of the gold and, where relevant, copper grades in the deposits, reflecting areas of higher and lower grades.
Density measurements are considered to provide acceptable density values for use in mineral resource and mineral reserve estimation.
The sample preparation, analysis, quality control, and security procedures used by the Nevada Operations have changed over time to meet evolving industry practices. Practices at the time the information was collected were industry-standard, and frequently were industry-leading practices. The sample preparation, analysis, quality control, and security procedures are sufficient to provide reliable data to support estimation of mineral resources and mineral reserves.
The QA/QC programs adequately address issues of precision, accuracy and contamination. Modern drilling programs typically included blanks, duplicates and standard samples. QA/QC submission rates meet industry-accepted standards.
22.8 Data Verification
Validation checks are performed by NGM operations personnel on data used to support estimation comprise checks on surveys, collar coordinates, lithology data (cross-checking from photographs), and assay data. Errors noted are rectified in the database prior to data being flagged as approved for use in resource estimation.
Reviews performed by external consultants were undertaken in support of acquisitions, support of feasibility-level studies, and in support of technical reports, producing independent assessments of the database quality. No significant problems with the database, sampling protocols, flowsheets, check analysis program, or data storage were noted.
NGM considers that a reasonable level of verification has been completed, and that no material issues would have been left unidentified from the programs undertaken.
The QP requested that information, conclusions, and recommendations presented in the body of this Report be reviewed by Newmont staff as a further level of data verification. Feedback from the reviewers was incorporated into the Report as required.
| | | | | | | | |
Date: February, 2022 | | Page 22-3 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
The QP has reviewed the reports and is of the opinion that the data verification programs completed on the data collected from the Project are consistent with industry best practices and that the database is sufficiently error-free to support the geological interpretations and mineral resource and mineral reserve estimation, and mine planning.
22.9 Metallurgical Testwork
Industry-standard studies were performed as part of process development and initial mill design. Subsequent production experience and focused investigations guided mill alterations and process changes. Testwork programs, both internal and external, continue to be performed to support current operations and potential improvements. From time to time, this may lead to requirements to adjust cut-off grades, modify the process flowsheet, or change reagent additions and plant parameters to meet concentrate quality, production, and economic targets.
Samples selected for testing were representative of the various types and styles of mineralization. Samples were selected from a range of depths within the deposit. Sufficient samples were taken so that tests were performed on sufficient sample mass.
Recovery factors estimated are based on appropriate metallurgical testwork, and are appropriate to the mineralization types and the selected process routes. Gold recovery is a function of the processing method (e.g., heap leaching, CIL, roasting, and arsenic concentration for refractory ore) and the lithology of the mineralization being processed. As applicable, recovery estimates include consideration of the head grade, cyanide-soluble gold to fire assay gold ratio, sulfide sulfur concentration, total organic carbon concentration, and silica concentration. Copper recovery models were derived from a statistical review of the metallurgical data and range in complexity from simple, fixed recoveries to complex, multi-variable equations. The following input variables were available as possible drivers of recovery: head grade, copper leach ore type, alteration type, formation, and various trace elements.
The mill throughput and associated recovery factors are considered appropriate to support mineral resource and mineral reserve estimation, and mine planning.
Depending upon the specific processing facility, several processing factors or deleterious elements could have an economic impact on extraction efficiency of a certain ore source, based either on the presence, absence, or concentration of the following constituents in the processing stream: organic carbon; sulfide sulfur; carbonate carbon; arsenic; mercury; antimony; and copper. However, under normal ore routing and blending practices at NGM where material from several sites may be processed at one facility, the above list of constituents is typically not a concern.
22.10 Mineral Resource Estimates
NGM has a set of protocols, internal controls, and guidelines in place to support the mineral resource estimation process.
All mineralogical information, exploration boreholes and background information were provided to the estimators by the geological staff at the mines or by exploration staff.
Mineral resources are reported using the mineral resource definitions set out in SK1300, and are reported exclusive of those mineral resources converted to mineral reserves. The reference
| | | | | | | | |
Date: February, 2022 | | Page 22-4 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
point for the estimate is in situ. Mineral resources are reported on a 100% basis. Barrick owns a 61.5% JV interest, with Newmont owning the remaining 38.5% JV interest.
Factors that may affect the Mineral Resource estimate include: changes to long-term metal price assumptions; changes in local interpretations of mineralization geometry and continuity of mineralized zones; changes to geological and grade shape and geological and grade continuity assumptions; changes to input parameters used in the pit shells and stope outlines constraining the Mineral Resources; changes to the cut-off grades used to constrain the estimates; variations in geotechnical, mining, and processing recovery assumptions; and changes to environmental, permitting and social license assumptions.
22.11 Mineral Reserve Estimates
Mineral reserves were converted from measured and indicated mineral resources. Inferred mineral resources were set to waste.
All current mineral reserves will be exploited using open pit mining methods, underground mining methods, or are in stockpiles. Mineral reserves amenable to open pit mining methods were estimated assuming open pit methods with conventional methods for drilling, blasting, loading with hydraulic shovels and haulage by large trucks. Mineral reserves amenable to underground mining methods were estimated assuming conventional stoping methods. Mineral resources were converted to mineral reserves using a detailed mine plan, an engineering analysis, and consideration of appropriate modifying factors. Modifying factors include the consideration of dilution and ore losses, open pit and underground mining methods, metallurgical recoveries, permitting and infrastructure requirements.
Mineral reserves are reported using the mineral reserve definitions set out in SK1300. The reference point for the estimate is the point of delivery to the process facilities. Mineral reserves are reported on a 100% basis. Barrick owns a 61.5% JV interest, with Newmont owning the remaining 38.5% JV interest.
Factors that may affect the mineral reserve estimates include: changes to the gold price assumptions; changes in the metallurgical recovery factors; changes to the operating cut-off assumptions for mill feed or stockpile feed; changes to the input assumptions used to derive the open pit and stope outlines and the mine plan that is based on those open pit and stope designs; changes to operating, and capital assumptions used, including changes to input cost assumptions such as consumables, labor costs, royalty and taxation rates; variations in geotechnical, hydrogeological, dilution and mining assumptions; including changes to pit phase or stope designs as a result of changes to geotechnical, hydrogeological, and engineering data used; changes to the assumed permitting and regulatory environment under which the mine plan was developed; ability to maintain mining permits and/or surface rights; ability to permit the expanded TSF and obtain the operations certificate for current and future underground operations; ability to maintain social and environmental license to operate.
22.12 Mining Methods
Mining operations can be conducted year-round.
Open pit mining is conducted using conventional techniques and an Owner-operated conventional truck and shovel fleet. The open pit mine plans are appropriately developed to
| | | | | | | | |
Date: February, 2022 | | Page 22-5 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
maximize mining efficiencies, based on the current knowledge of geotechnical, hydrological, mining and processing information on the Project.
Underground mining is currently conducted using conventional stoping or cut-and-fill methods, and conventional mechanized equipment. The underground mine plans are based on the current knowledge of geotechnical, hydrological, mining and processing information. At certain sites, adjustments to mining methods is in process to reflect rock mass conditions.
The LOM plan assumes 577.2 Mt of ore and 1,201.7 Mt of waste will be mined.
As part of day-to-day operations, NGM will continue to perform reviews of the mine plan and consider alternatives to, and variations within, the plan. Alternative scenarios and reviews may be based on ongoing or future mining considerations, evaluation of different potential input factors and assumptions, and corporate directives.
22.13 Recovery Methods
The process facilities designs were based on a combination of metallurgical testwork, previous study designs, previous operating experience. The designs are generally conventional to the gold industry and have no novel parameters.
The facilities will produce variations in recovery due to the day-to-day changes in ore type or combinations of ore type being processed. These variations are expected to trend to the forecast recovery value for monthly or longer reporting periods.
22.14 Infrastructure
The majority of the key infrastructure to support the mining activities envisaged in the LOM is in place. New infrastructure will be required to support proposed operations at Goldrush and Robertson. A third shaft is in progress at the Turquoise Ridge Complex.
A stockpiling strategy is practiced to defer lower-grade ores to the end of mine life.
There is sufficient capacity in the existing heap leach pads and planned heap leach pad expansions, existing WRSFs and planned WRSF expansions, and existing TSFs and planned TSF expansions for LOM planning purposes.
The current water sources, assuming similar climate conditions to those experienced by the operations in the past, will be sufficient for the LOM plan.
The current water management practices are expected to be applicable for the LOM plan.
The existing infrastructure, staff availability, existing power, water, and communications facilities, and the methods whereby goods are transported to the mine are all in place and well-established, and can support the estimation of mineral resources and mineral reserves. Requirements for additional infrastructure to support the proposed operations at Goldrush and Robertson are well understood.
Personnel commute from surrounding settlements.
Electrical power for the Carlin, Cortez, Turquoise Ridge, and Phoenix Complexes is obtained via TS Power Plant and from the Western 102 power plant (both of which are owned and operated
| | | | | | | | |
Date: February, 2022 | | Page 22-6 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
by NGM) with transmission by NV Energy. Power for Gold Quarry, Long Canyon, and Goldrush is supplied via the Wells Rural Electric Power Company.
22.15 Market Studies
NGM has established contracts and buyers for the gold bullion, copper concentrate and copper cathode products from the Nevada Operations. Together with public documents and analyst forecasts, these data support that there is a reasonable basis to assume that for the LOM plan, that the key products will be saleable at the assumed commodity pricing.
Barrick, as operator of the NGM JV, provides the commodity price guidance. Higher metal prices are used for the mineral resource estimates to ensure the mineral reserves are a sub-set of, and not constrained by, the mineral resources, in accordance with industry-accepted practice.
NGM has contracts in place for the majority of the copper concentrate with smelters and various traders. The terms contained within the sales contract are typical of and consistent with standard industry practice and are like contracts for the supply of copper concentrate throughout the world. The Phoenix copper leach facility produces cathode copper which is sold to a trader who re-sells for product manufacturing. The terms contained within the sales contract are typical of and consistent with standard industry practice and are like contracts for the supply of copper cathode globally.
NGM’s bullion is sold on the spot market, by marketing experts retained in-house by NGM/Barrick. NGM provides Newmont with the date and number of ounces that will be credited to Newmont’s account, and invoices Newmont for how much NGM is owed, such that Newmont receives credits for the ounces (based on the JV interest) and Newmont pays NGM for the ounces. The terms contained within the sales contracts are typical and consistent with standard industry practice and are similar to contracts for the supply of bullion elsewhere in the world.
The largest in-place contracts other than for product sales cover items such as bulk commodities, operational and technical services, mining and process equipment, and administrative support services. Contracts are negotiated and renewed as needed.
22.16 Environmental, Permitting and Social Considerations
Baseline and supporting environmental studies were completed to assess both pre-existing and ongoing site environmental conditions, as well as to support decision-making processes during operations start-up. Characterization studies were completed for climate, air quality, hydrology and surface water quality, hydrogeology, flora, fauna, soils, agriculture and land use, and the socioeconomic environment.
Plans were developed and implemented to address aspects of operations such as waste and fugitive dust management, spill prevention and contingency planning, water management, and noise levels.
NGM currently has posted approximately US$2.14 B in financial assurances in the form of letters of credit and surety bonds to cover mine closure costs. Additionally, there are several trusts associated with closure cost planning.
| | | | | | | | |
Date: February, 2022 | | Page 22-7 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
As part of its permitting requirements, NGM has submitted and received approval on numerous PoOs and Reclamation Plans for each area. NGM has submitted and/or provided information to support NEPA evaluation for each area containing public lands. The PoOs are updated and amended as necessary to allow for continuation of mining or additional mine development. The Nevada Operations have the required permits to operate or will be applying for the permits as they are required for mine development. Additional permits will be required to support planned operations at Goldrush with about 20 key permits required for Goldrush.
Nevada Gold Mines is one of the largest direct employers in the area and also generates significant indirect employment. Prior to the formation of NGM, Barrick had a robust community relations and social performance strategy and a dedicated team to execute on that strategy. This has continued under NGM. Stakeholder engagement is a primary pillar of that strategy and includes participation in local civic activities; city/town council and county commission meetings; serving on boards and committees; town hall meetings; and one-to-one engagement. From this engagement, NGM listens to, and partners with, local organizations to identify a social investment strategy.
As part of the community affairs program, NGM engages with 10 tribal communities. Engagement with partner tribes includes regularly-held meetings called “Dialogue Meetings”; tribal council meetings; community committees; one-to-one engagements and sponsorship of several community-driven initiatives. Through this engagement, NGM works with tribal councils to identify and support community priorities in programs aimed at improving community health and well-being, education attainment, cultural heritage preservation, and economic development.
The Cortez Complex, including the Goldrush project, operate on lands traditionally used by the Western Shoshone tribes and bands, and NGM makes efforts to demonstrate respect for indigenous cultural resources, environmental stewardship, and shared benefits to receive support from Western Shoshone communities.
As the Goldrush project develops, NGM will hold public meetings (and advertise a local grievance mechanism according to the Grievance Management Procedure) if internal strategy deems appropriate so that citizens in the surrounding areas may come to learn more about the project and express their support or concerns.
22.17 Capital Cost Estimates
Capital costs were based on recent prices or operating data and are at a minimum at a pre-feasibility level of confidence, having an accuracy level of ±25% and a contingency range not exceeding 15%.
Capital costs included funding for infrastructure, pit dewatering, development drilling, and permitting as well as miscellaneous expenditures required to maintain production. Mobile equipment re-build/replacement schedules and fixed asset replacement and refurbishment schedules were included. Sustaining capital costs reflected current price trends.
The overall capital cost estimate for the LOM is US$2.6 B.
| | | | | | | | |
Date: February, 2022 | | Page 22-8 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
22.18 Operating Cost Estimates
Operating costs were based on actual costs seen during operations and are projected through the LOM plan, and are at a minimum at a pre-feasibility level of confidence, having an accuracy level of ±25% and a contingency range not exceeding 15%.
Historical costs were used as the basis for operating cost forecasts for supplies and services unless there are new contract terms for these items. Labor and energy costs were based on budgeted rates applied to headcounts and energy consumption estimates.
The LOM operating costs are estimated at US$34.9 B. The average mining costs (open pit and underground) over the LOM are US$10.47/t mined, autoclave costs are US$34.01/t processed, roaster costs are US$24.12/t processed, oxide mill costs are US$10.46/t processed, heap leach costs are US$3.53/t processed, and general and administrative costs (inclusive of transport costs) are US$5.78/t processed.
22.19 Economic Analysis
The NPV5% is US$4.2 B on a 100% basis. Barrick owns a 61.5% JV interest, with Newmont owning the remaining 38.5% JV interest.
Due to the profile of the cashflow, considerations of payback and internal rate of return are not relevant.
22.20 Risks and Opportunities
Factors that may affect the mineral resource and mineral reserve estimates were identified in Chapter 11.13 and Chapter 12.9 respectively.
22.20.1 Risks
The risks associated with the Nevada Operations are generally those expected with open pit and underground mining operations and include the accuracy of the resource models, unexpected geological features that cause geotechnical issues, and/or operational impacts.
Other risks noted include:
•Commodity price increases for key consumables such diesel, electricity, tires and chemicals would negatively impact the stated mineral reserves and mineral resources;
•Labor cost increases or productivity decreases could also impact the stated mineral reserves and mineral resources, or impact the economic analysis that supports the mineral reserves;
•Geotechnical and hydrological assumptions used in mine planning are based on historical performance, and to date historical performance has been a reasonable predictor of current conditions. Any changes to the geotechnical (seismicity) and hydrological assumptions could affect mine planning, affect capital cost estimates if any major rehabilitation is required due to a geotechnical or hydrological event, affect operating costs due to mitigation measures that may need to be imposed, and impact the economic analysis that supports the mineral reserve estimates;
| | | | | | | | |
Date: February, 2022 | | Page 22-9 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
•The mineral resource estimates are sensitive to metal prices. Lower metal prices require revisions to the mineral resource estimates;
•The LOM plan assumes that new TSFs can be permitted based on envisaged timelines. If the permitting schedule is delayed, this could impact costs and proposed production;
•Updated industry standards for TSFs may have an impact on the envisaged TSF costs;
•The LOM plan assumes that ore is sent to the process facility that will provide optimal results (costs, metallurgical recoveries). Should, for operational reasons, a different process facility be selected, then higher operating costs and/or lower recoveries may result;
•The LOM plan envisages blending of numerous ore sources at the various process facilities. Non-optimal blends could impact operating costs, plant throughputs, and metallurgical recoveries. There may be potential for exceedances on environmental monitoring limits if such blends are not well controlled;
•Stockpiled materials can undergo degradation over time, and the metallurgical recoveries assumed for stockpiled materials may be lower than that assumed in the LOM plan;
•Management of threatened and endangered species may delay permits and increase capital and/or operating costs. Although there are site-specific management plans, either planned or in place, if there is a major impact seen on the populations from mining activities, the environmental permits for the operations could be revised or even revoked. The social license to operate could also be impacted;
•Regulatory approval of the Goldrush project is still pending, and the project is in the EIA process. If conditions are imposed by the regulators as a result of the process, this could impact the project schedule and cost estimates;
•On-highway transport of ore or concentrate could be impacted by changes to regulations on the number of trucks that can be used;
•Exceedances of permit conditions have historically occurred at certain of the process facilities. Should such exceedances recur, there could be social and regulatory impacts to operations, mine plans, and the forecast economic analyses;
•Climate changes could impact operating costs and ability to operate;
•The long-term reclamation and mitigation of the Nevada Operations are subject to assumptions as to closure timeframes and closure cost estimates. If these cannot be met, there is a risk to the costs and timing;
•Newmont is the minority partner in the NGM JV and does not exercise day-to-day control over NGM’s operations;
•Political risk from challenges to the current state or federal mining laws.
22.20.2 Opportunities
Opportunities include:
•Conversion of some or all of the measured and indicated mineral resources currently reported exclusive of mineral reserves to mineral reserves, with appropriate supporting studies;
| | | | | | | | |
Date: February, 2022 | | Page 22-10 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
•Upgrade of some or all of the inferred mineral resources to higher-confidence categories, such that this higher-confidence material could potentially be converted to mineral reserve estimates;
•Higher metal prices than forecast could present upside sales opportunities and potentially an increase in predicted Project economics;
•NGM holds a significant ground package within the AOI that retains significant exploration potential:
◦Exploration potential around current and historical open pits;
◦Potential for new underground operations proximal to the current mineral resource and mineral reserve estimates, with the support of additional studies.
22.21 Conclusions
Under the assumptions presented in this Report, the Nevada Operations have a positive cashflow, and mineral reserve estimates can be supported.
| | | | | | | | |
Date: February, 2022 | | Page 22-11 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
23.0 RECOMMENDATIONS
As the Nevada Operations are a complex of operating mines, the QP has no material recommendations to make.
| | | | | | | | |
Date: February, 2022 | | Page 23-1 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
24.0 REFERENCES
24.1 Bibliography
Altman, K.A., Bergen, R.D., Collins, S.E., Moore, C.M., and Valliant, W.W., 2016: Technical Report on the Cortez Operations, State of Nevada, U.S.A., NI 43-101 report; report prepared by Roscoe Postle Associates Inc. for Barrick Gold Corporation, effective date March 21, 2016
Bergen, R.D., Gareau, M.B., and Altman, K.A., 2012: Technical Report On The Cortez Joint Venture Operations, Lander And Eureka Counties, State Of Nevada, U.S.A. NI 43-101: report prepared by Roscoe Postle Associates Inc. for Barrick Gold Corporation, effective date March 16, 2012.
Bolin, L., Fiddes, C., Yopps, S.W., 2020: Technical Report On The Turquoise Ridge Complex, State Of Nevada, USA NI 43-101 Report: Prepared For Newmont Corporation And Barrick Gold Corporation By Nevada Gold Mines LLC effective date December 31, 2019.
Cox., J.J., Valliant, W.W., Altman, K.A., Geusebroek, P.A., 2018: Technical Report On The Turquoise Ridge Mine, State Of Nevada, U.S.A. NI 43-101 Report: report prepared by Roscoe Postle Associates Inc. for Barrick Gold Corporation, effective date March 19, 2018.
Cox., J.J., Geusebroek, P.A., Valliant, W.W., Haggarty, S., 2019: Technical Report On The Goldstrike Mine, Eureka And Elko Counties, State Of Nevada, USA NI 43-101 Report: report prepared by Roscoe Postle Associates Inc. for Barrick Gold Corporation, effective date March 22, 2019.
Doe, D., 2018: Carlin Operations, Nevada USA, NI 43-101 Report: report prepared for Newmont Mining Corporation, effective date 31 December, 2018.
Evans, L., Collins, S.E., Cox, J.J., Krutzelmann, H., 2017: Technical Report On The Goldstrike Mine, Eureka And Elko Counties, Nevada U.S.A. NI 43-101 Report: report prepared by Roscoe Postle Associates Inc. for Barrick Gold Corporation, effective date April 25, 2017.
Fiddes, C., Olcott, J., Bolin, C.L. and Yopps, S.W., 2020: Technical Report On The Carlin Complex, Eureka And Elko Counties, State Of Nevada, USA: report prepared for Barrick Gold Corporation and Newmont Corporation by Nevada Gold Mines LLC, effective date March 25, 2020.
Gustin, M.M. and Smith, M., 2009: Technical Report on the Long Canyon Project, Elko County, Nevada, USA: report prepared by Mine Development Associates for Fronteer Development Group Inc., effective date April 17, 2009.
Heitt, D.G., 2002: Newmont’s Reserve History on the Carlin Trend, 1965–2001: in Thompson, T.B., Teal, L., and Meeuwig, R.O., eds, Gold Deposits of the Carlin Trend, Nevada Bureau of Mines and Geology Bulletin 111, pp. 35–45.
Hofstra A.H., Leventhal J.S., Northrop H.R., Landis G.P., Rye R.O., Birak D.J., and Dahl A.R., 1991: Genesis Of Sediment-Hosted Disseminated Gold Deposits By Fluid Mixing And Sulfidization: Chemical-Reaction-Path Modeling Of Ore-Depositional Processes Documented In The Jerritt Canyon District, Nevada: Geology 19:36–40.
| | | | | | | | |
Date: February, 2022 | | Page 24-1 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Hotz, P.E., 1963: Geology and Mineral Deposits of the Osgood Mountains Quadrangle, Humboldt County, Nevada, Preston E. Hotz and Ronald Wilden. Washington, U.S. Government Printing Office, 1963.
Jory, J., 2002: Stratigraphy and Host Rock Controls of Gold Deposits of the Northern Carlin Trend: in Thompson, T.B., Teal, L., and Meeuwig, R.O., eds, Gold Deposits of the Carlin Trend, Nevada Bureau of Mines and Geology Bulletin 111, pp. 20–34.
Miranda, H., Altman, K.A., Geusebroek, P.A., Valliant, W.W., Bergen, R.D., 2019: Technical Report On The Cortez Joint Venture Operations, Lander And Eureka Counties, State Of Nevada, U.S.A. NI 43-101 Report: report prepared by Roscoe Postle Associates Inc. for Barrick Gold Corporation, March 22, 2019.
Moore, C.M., Bergen, R.D., Valliant, W.W., Collins, S.E., Altman, K.A., 2012: Technical Report On The Goldstrike Mine, Eureka & Elko Counties, State Of Nevada, U.S.A., NI 43-101 Report: report prepared by Roscoe Postle Associates Inc. for Barrick Gold Corporation, effective date March 16, 2012.
Nevada Gold Mines, 2020: Qualified Persons Summary to Support Year End Reserves and Resources, Cortez; report prepared year-end 31 December, 2020.
Nevada Gold Mines, 2020: Qualified Persons Summary to Support Year End Reserves and Resources, Goldrush; report prepared year-end 31 December, 2020.
Nevada Gold Mines, 2020: Qualified Persons Summary to Support Year End Reserves and Resources, Carlin Complex; report prepared year-end 31 December, 2020.
Nevada Gold Mines, 2020: Qualified Persons Summary to Support Year End Reserves and Resources, Arturo South; report prepared year-end 31 December, 2020.
Nevada Gold Mines, 2020: Qualified Persons Summary to Support Year End Reserves and Resources, Long Canyon; report prepared year-end 31 December, 2020.
Nevada Gold Mines, 2020: Qualified Persons Summary to Support Year End Reserves and Resources, Phoenix; report prepared year-end 31 December, 2020.
Nevada Gold Mines, 2021: Goldrush Underground Mine Feasibility Study: draft August, 2021.
Nevada Gold Mines, 2021: Goldrush Underground Mine Feasibility Study: draft October, 2021.
Papke, K.G., and Davis, D.A., 2019: Mining Claim Procedures for Nevada Prospectors and Miners, Fifth Edition: Nevada Bureau of Mines and Geology, Mackay School of Mines, 2019 update, 58 p.
Rhys, D., Valli, F., Burgess, R., Heitt, D., Griesel, G. and Hart, K., 2015: Controls of Fault and Fold Geometry on the Distribution of Gold Mineralization on the Carlin Trend: in Prennell, W.M. and Garside, L.J., eds, New Concepts and Discoveries. Geological Society of Nevada 2015 Symposium. Vol. Geological Society of Nevada Reno/Sparks, NV, p. 333–389.
Smith, M.T., Rhys, D., Ross, K., Lee, C., and Gray, J.N., 2013: The Long Canyon Deposit: Anatomy of a New Off-Trend Sedimentary Rock-Hosted Gold Discovery in Northeastern Nevada: Economic Geology, vol. 108(5), pp. 1119–1145.
Stewart, J.H., 1980: Geology of Nevada: a discussion to accompany the Geologic Map of Nevada: Nevada Bureau of Mines and Geology Special Publication, No. 4, 136 p.
| | | | | | | | |
Date: February, 2022 | | Page 24-2 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
Teal, L., and Jackson, M., 2002: Geologic Overview of the Carlin Trend Gold Deposits: in Thompson T.B., Teal, L., and Meeuwig, R.O., eds., Gold Deposits of the Carlin Trend: Nevada Bureau of Mines and Geology, Bulletin 111, p. 9–19.
24.2 Abbreviations
| | | | | |
Abbreviation/Symbol | Term |
AAL | American Assay Laboratory |
ALS | ALS Chemex |
BLM | US Bureau of Land Management |
BMRR | Bureau of Mining Regulation and Reclamation |
CAI | organic carbon |
CIC | carbon-in-columns |
CRF | capital recovery factor |
CSAMT | controlled-source audio-frequency telluromagnetics |
DNA | Determination of NEPA Adequacy |
DWR | State Division of Water Resources |
EA | Environmental Assessments |
EIA | Environmental Impact Assessment |
EIS | Environmental Impact Statement |
Elliot | Elliot Geophysical Laboratories |
EM | electromagnetics |
FA | fire assay |
FONSI | Findings of No Significant Impacts |
G&A | general and administrative |
GPS | global positioning system |
GSI | geological strength index |
ICP | inductively coupled plasma |
ICP AES | inductively coupled plasma–atomic emission spectroscopy |
ICP-MS | inductively coupled plasma–mass spectrometry |
ID2 | inverse distance to the power of two |
ID3 | inverse distance to the power of three |
ID5 | inverse distance to the power of five |
IK | indicator kriging |
IP | induced polarization |
IRMR | in situ rock mass rating |
LG | Lerchs–Grossmann |
LIK | Local indicator kriging |
LOM | life-of-mine |
MSO | Mineable Stope Optimizer |
MT | magnetotellurics |
NAC | Nevada Administrative Code |
NaCN | cyanide |
NAL | North Area Leach pads |
NDEP | Nevada Division of Environmental Protection |
NEPA | National Environmental Policy Act |
Newmont | Newmont Mining Corporation |
NEX | North East Extension |
NN | nearest neighbor |
| | | | | | | | |
Date: February, 2022 | | Page 24-3 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
| | | | | |
Abbreviation/Symbol | Term |
OK | ordinary kriging |
PAG | potentially acid-generating |
PoO | Plan of Operations |
QA/QC | quality assurance and quality control |
QP | Qualified Person |
RC | reverse circulation |
RIL | resin-in-leach |
RMR | rock mass rating |
ROD | Record of Decision |
ROM | run-of-mine |
RQD | rock quality description |
SAG | semi-autogenous grind |
SAL | South Area leach pads |
Sdrm | Silurian Roberts Mountain |
SDrm | Siluro-Devonian Roberts Mountains Formation |
SME | Society for Mining, Metallurgy and Exploration |
SP | self-potential |
SRCE | Standard Reclamation Cost Estimator |
SRM | standard reference materials |
SX/EW | solvent extraction and electrowinning |
TSF | tailing storage facility |
US | United States |
USGS | US Geological Survey |
WPCPs | water pollution control permits |
WRSF | waste rock storage facilities |
XRD | X-ray diffraction |
XRF | X-ray fluorescence |
Zonge | Zonge Engineering |
24.3 Glossary of Terms
| | | | | |
Term | Definition |
advanced argillic alteration | Consists of kaolinite + quartz + hematite + limonite. feldspars leached and altered to sericite. The presence of this assemblage suggests low pH (highly acidic) conditions. At higher temperatures, the mineral pyrophyllite (white mica) forms in place of kaolinite |
alluvium | Unconsolidated terrestrial sediment composed of sorted or unsorted sand, gravel, and clay that has been deposited by water. |
aquifer | A geologic formation capable of transmitting significant quantities of groundwater under normal hydraulic gradients. |
argillic alteration | Introduces any one of a wide variety of clay minerals, including kaolinite, smectite and illite. Argillic alteration is generally a low temperature event, and some may occur in atmospheric conditions |
autoclave | A special reaction vessel designed for high pressure and temperature hydrometallurgical reactions, for example in the treatment of refractory ores |
ball mill | A piece of milling equipment used to grind ore into small particles. It is a cylindrical shaped steel container filled with steel balls into which crushed ore is fed. The ball mill is rotated causing the balls themselves to cascade, which in turn grinds the ore. |
| | | | | | | | |
Date: February, 2022 | | Page 24-4 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
| | | | | |
Term | Definition |
Bond work index | A measure of the energy required to break an ore to a nominal product size, determined in laboratory testing, and used to calculate the required power in a grinding circuit design. |
bullion | Unrefined gold and/or silver mixtures that have been melted and cast into a bar or ingot. |
carbon-in-column | A method of recovering gold and silver from rich solution from the heap leaching process by adsorption of the precious metals onto fine carbon suspended by up-flow of solution through a tank. |
carbon-in-leach | A method of recovering gold and silver from fine ground ore by simultaneous dissolution and adsorption of the precious metals onto fine carbon in an agitated tank of ore solids/solution slurry. The carbon flows counter currently to the head of the leaching circuit. |
carbonaceous | Containing graphitic or hydrocarbon species, e.g. in an ore or concentrate; such materials generally present some challenge in processing, e.g. preg-robbing characteristics. |
comminution/crushing/grinding | Crushing and/or grinding of ore by impact and abrasion. Usually, the word “crushing” is used for dry methods and “grinding” for wet methods. Also, “crushing” usually denotes reducing the size of coarse rock while “grinding” usually refers to the reduction of the fine sizes. |
concentrate | The concentrate is the valuable product from mineral processing, as opposed to the tailing, which contains the waste minerals. The concentrate represents a smaller volume than the original ore |
cut-and-fill | Cut-and-fill stoping is a preferred method for high-grade ore bodies with a steep dip size or irregular shape or vein structure. It is also useful for deposits that have weak walls as the fill supports the slope walls and provides a platform for when the next slice is cut. |
cut-off grade | The grade (i.e., the concentration of metal or mineral in rock) that determines the destination of the material during mining. For purposes of establishing “prospects of economic extraction,” the cut-off grade is the grade that distinguishes material deemed to have no economic value (it will not be mined in underground mining or if mined in surface mining, its destination will be the waste dump) from material deemed to have economic value (its ultimate destination during mining will be a processing facility). Other terms used in similar fashion as cut-off grade include net smelter return, pay limit, and break-even stripping ratio. |
cyanidation | A method of extracting gold or silver by dissolving it in a weak solution of sodium cyanide. |
data verification | The process of confirming that data has been generated with proper procedures, has been accurately transcribed from the original source and is suitable to be used for mineral resource and mineral reserve estimation |
decline | A sloping underground opening for machine access from level to level or from the surface. Also called a ramp. |
density | The mass per unit volume of a substance, commonly expressed in grams/ cubic centimeter. |
depletion | The decrease in quantity of ore in a deposit or property resulting from extraction or production. |
development | Often refers to the construction of a new mine or; Is the underground work carried out for the purpose of reaching and opening up a mineral deposit. It includes shaft sinking, cross-cutting, drifting and raising. |
development property | a property that is being prepared for mineral production or a material expansion of current production, and for which economic viability has been demonstrated by a pre-feasibility or feasibility study. |
| | | | | | | | |
Date: February, 2022 | | Page 24-5 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
| | | | | |
Term | Definition |
dilution | Waste of low-grade rock which is unavoidably removed along with the ore in the mining process. |
drift | A horizontal mining passage underground. A drift usually follows the ore vein, as distinguished from a crosscut, which intersects it. |
easement | Areas of land owned by the property owner, but in which other parties, such as utility companies, may have limited rights granted for a specific purpose. |
electrowinning. | The removal of precious metals from solution by the passage of current through an electrowinning cell. A direct current supply is connected to the anode and cathode. As current passes through the cell, metal is deposited on the cathode. When sufficient metal has been deposited on the cathode, it is removed from the cell and the sludge rinsed off the plate and dried for further treatment. |
elution | Recovery of the gold from the activated carbon into solution before zinc precipitation or electro-winning. |
EM | Geophysical method, electromagnetic system, measures the earth's response to electromagnetic signals transmitted by an induction coil |
encumbrance | An interest or partial right in real property which diminished the value of ownership, but does not prevent the transfer of ownership. Mortgages, taxes and judgements are encumbrances known as liens. Restrictions, easements, and reservations are also encumbrances, although not liens. |
feasibility study | A feasibility study is a comprehensive technical and economic study of the selected development option for a mineral project, which includes detailed assessments of all applicable modifying factors, as defined by this section, together with any other relevant operational factors, and detailed financial analysis that are necessary to demonstrate, at the time of reporting, that extraction is economically viable. The results of the study may serve as the basis for a final decision by a proponent or financial institution to proceed with, or finance, the development of the project. A feasibility study is more comprehensive, and with a higher degree of accuracy, than a pre-feasibility study. It must contain mining, infrastructure, and process designs completed with sufficient rigor to serve as the basis for an investment decision or to support project financing. |
flotation | Separation of minerals based on the interfacial chemistry of the mineral particles in solution. Reagents are added to the ore slurry to render the surface of selected minerals hydrophobic. Air bubbles are introduced to which the hydrophobic minerals attach. The selected minerals are levitated to the top of the flotation machine by their attachment to the bubbles and into a froth product, called the “flotation concentrate.” If this froth carries more than one mineral as a designated main constituent, it is called a “bulk float”. If it is selective to one constituent of the ore, where more than one will be floated, it is a “differential” float. |
flowsheet | The sequence of operations, step by step, by which ore is treated in a milling, concentration, or smelting process. |
footwall | The wall or rock on the underside of a vein or ore structure. |
frother | A type of flotation reagent which, when dissolved in water, imparts to it the ability to form a stable froth |
gangue | The fraction of ore rejected as tailing in a separating process. It is usually the valueless portion, but may have some secondary commercial use |
gravity separation | Exploitation of differences in the densities of particles to achieve separation. Machines utilizing gravity separation include jigs and shaking tables. |
hanging wall | The wall or rock on the upper or top side of a vein or ore deposit. |
| | | | | | | | |
Date: February, 2022 | | Page 24-6 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
| | | | | |
Term | Definition |
heap leaching | A process whereby valuable metals, usually gold and silver, are leached from a heap or pad of crushed ore by leaching solutions percolating down through the heap and collected from a sloping, impermeable liner below the pad. |
hydrometallurgy | A type of extractive metallurgy utilizing aqueous solutions/solvents to extract the metal value from an ore or concentrate. Leaching is the predominant type of hydrometallurgy. |
indicated mineral resource | An 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 term adequate geological evidence means evidence that is sufficient to establish geological and grade or quality continuity with reasonable certainty. 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. |
inferred mineral resource | An 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 term limited geological evidence means evidence that is only sufficient to establish that geological and grade or quality continuity is more likely than not. 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. A qualified person must have a reasonable expectation that the majority of inferred mineral resources could be upgraded to indicated or measured mineral resources with continued exploration; and should be able to defend the basis of this expectation before his or her peers. |
initial assessment | An initial assessment is a preliminary technical and economic study of the economic potential of all or parts of mineralization to support the disclosure of mineral resources. The initial assessment must be prepared by a qualified person and must include appropriate assessments of reasonably assumed technical and economic factors, together with any other relevant operational factors, that are necessary to demonstrate at the time of reporting that there are reasonable prospects for economic extraction. An initial assessment is required for disclosure of mineral resources but cannot be used as the basis for disclosure of mineral reserves |
internal rate of return (IRR) | The rate of return at which the Net Present Value of a project is zero; the rate at which the present value of cash inflows is equal to the present value of the cash outflows. |
IP | Geophysical method, induced polarization; used to directly detect scattered primary sulfide mineralization. Most metal sulfides produce IP effects, e.g. chalcopyrite, bornite, chalcocite, pyrite, pyrrhotite |
Knelson concentrator | a high-speed centrifuge that combines centrifugally enhanced gravitational force with a patented fluidization process to recover precious metals |
life of mine (LOM) | Number of years that the operation is planning to mine and treat ore, and is taken from the current mine plan based on the current evaluation of ore reserves. |
lithogeochemistry | The chemistry of rocks within the lithosphere, such as rock, lake, stream, and soil sediments |
lixiviant | A leach liquor used to dissolve a constituent in an ore, for example a cyanide solution used to dissolve gold. |
| | | | | | | | |
Date: February, 2022 | | Page 24-7 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
| | | | | |
Term | Definition |
long-hole stoping | Long-hole sublevel stoping, often referred to as sublevel open stoping and blast hole stoping is a commonly-used method in large-scale mining. It is primarily used for large ore bodies with a steep dip, regular shape, and defined ore bodies. It is used when the ore body is narrow in width (20–100 ft) |
long-hole stope retreat | Similar mining method to long-hole stoping, except that the long axis of the stope is along (or parallel) to the strike of the orebody. |
magnetic separation | Use of permanent or electro-magnets to remove relatively strong ferromagnetic particles from para- and dia-magnetic ores. |
measured mineral resource | A 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 term conclusive geological evidence means evidence that is sufficient to test and confirm geological and grade or quality continuity. 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 this section, in sufficient detail to support detailed mine planning and final evaluation of the economic viability of the deposit. |
merger | A voluntary combination of two or more companies whereby both stocks are merged into one. |
mill | Includes any ore mill, sampling works, concentration, and any crushing, grinding, or screening plant used at, and in connection with, an excavation or mine. |
mineral reserve | A 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. The determination that part of a measured or indicated mineral resource is economically mineable must be based on a preliminary feasibility (pre-feasibility) or feasibility study, as defined by this section, conducted by a qualified person applying the modifying factors to indicated or measured mineral resources. Such study must demonstrate that, at the time of reporting, extraction of the mineral reserve is economically viable under reasonable investment and market assumptions. The study must establish a life of mine plan that is technically achievable and economically viable, which will be the basis of determining the mineral reserve. The term economically viable means that the qualified person has determined, using a discounted cashflow analysis, or has otherwise analytically determined, that extraction of the mineral reserve is economically viable under reasonable investment and market assumptions. The term investment and market assumptions includes all assumptions made about the prices, exchange rates, interest and discount rates, sales volumes, and costs that are necessary to determine the economic viability of the mineral reserves. The qualified person must use a price for each commodity that provides a reasonable basis for establishing that the project is economically viable. |
| | | | | | | | |
Date: February, 2022 | | Page 24-8 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
| | | | | |
Term | Definition |
mineral resource | A 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. The term material of economic interest includes mineralization, including dumps and tailings, mineral brines, and other resources extracted on or within the earth’s crust. It does not include oil and gas resources as defined in Regulation S-X (§210.4-10(a)(16)(D) of this chapter), gases (e.g., helium and carbon dioxide), geothermal fields, and water. When determining the existence of a mineral resource, a qualified person, as defined by this section, must be able to estimate or interpret the location, quantity, grade or quality continuity, and other geological characteristics of the mineral resource from specific geological evidence and knowledge, including sampling; and conclude that there are reasonable prospects for economic extraction of the mineral resource based on an initial assessment, as defined in this section, that he or she conducts by qualitatively applying relevant technical and economic factors likely to influence the prospect of economic extraction. |
mining claim | A description by boundaries of real property in which metal ore and/or minerals may be located. |
modifying factors | The factors that a qualified person must apply to indicated and measured mineral resources and then evaluate in order to establish the economic viability of mineral reserves. A qualified person must apply and evaluate modifying factors to convert measured and indicated mineral resources to proven and probable mineral reserves. These factors include, but are not restricted to: mining; processing; metallurgical; infrastructure; economic; marketing; legal; environmental compliance; plans, negotiations, or agreements with local individuals or groups; and governmental factors. The number, type and specific characteristics of the modifying factors applied will necessarily be a function of and depend upon the mineral, mine, property, or project. |
net present value (NPV) | The present value of the difference between the future cashflows associated with a project and the investment required for acquiring the project. Aggregate of future net cashflows discounted back to a common base date, usually the present. NPV is an indicator of how much value an investment or project adds to a company. |
net smelter return (NSR) | A defined percentage of the gross revenue from a resource extraction operation, less a proportionate share of transportation, insurance, and processing costs. |
open pit | A mine that is entirely on the surface. Also referred to as open-cut or open-cast mine. |
orogeny | A process in which a section of the earth's crust is folded and deformed by lateral compression to form a mountain range |
ounce (oz) (troy) | Used in imperial statistics. A kilogram is equal to 32.1507 ounces. A troy ounce is equal to 31.1035 grams. |
overburden | Material of any nature, consolidated or unconsolidated, that overlies a deposit of ore that is to be mined. |
overhand drift and fill | The orebody is initially mined using a horizontal slice. The mined-out slice is then backfilled to provide additional support for the country rock surrounding the stope. The backfilled material forms the base for executing the next, upper slice. In effect, in overhand cut-and-fill, the ore lies above the working area and the floor is backfill. |
| | | | | | | | |
Date: February, 2022 | | Page 24-9 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
| | | | | |
Term | Definition |
penalty elements | Elements that when recovered to a flotation concentrate, attract a penalty payment from the smelting customer. This is because those elements are deleterious, and cause quality, environmental or cost issues for the smelter. Includes elements such as, Hg and Pb. |
phyllic alteration | Minerals include quartz–sericite–pyrite |
plant | A group of buildings, and especially to their contained equipment, in which a process or function is carried out; on a mine it will include warehouses, hoisting equipment, compressors, repair shops, offices, mill or concentrator. |
portal | The surface entrance to a tunnel or adit |
potassic alteration | A relatively high temperature type of alteration which results from potassium enrichment. Characterized by biotite, K-feldspar, adularia. |
preliminary feasibility study, pre-feasibility study | A preliminary feasibility study (prefeasibility study) is a comprehensive study of a range of options for the technical and economic viability of a mineral project that has advanced to a stage where a qualified person has determined (in the case of underground mining) a preferred mining method, or (in the case of surface mining) a pit configuration, and in all cases has determined an effective method of mineral processing and an effective plan to sell the product. A pre-feasibility study includes a financial analysis based on reasonable assumptions, based on appropriate testing, about the modifying factors and the evaluation of any other relevant factors that are sufficient for a qualified person to determine if all or part of the indicated and measured mineral resources may be converted to mineral reserves at the time of reporting. The financial analysis must have the level of detail necessary to demonstrate, at the time of reporting, that extraction is economically viable |
probable mineral reserve | A probable mineral reserve is the economically mineable part of an indicated and, in some cases, a measured mineral resource. For a probable mineral reserve, the qualified person’s confidence in the results obtained from the application of the modifying factors and in the estimates of tonnage and grade or quality is lower than what is sufficient for a classification as a proven mineral reserve, but is still sufficient to demonstrate that, at the time of reporting, extraction of the mineral reserve is economically viable under reasonable investment and market assumptions. The lower level of confidence is due to higher geologic uncertainty when the qualified person converts an indicated mineral resource to a probable reserve or higher risk in the results of the application of modifying factors at the time when the qualified person converts a measured mineral resource to a probable mineral reserve. A qualified person must classify a measured mineral resource as a probable mineral reserve when his or her confidence in the results obtained from the application of the modifying factors to the measured mineral resource is lower than what is sufficient for a proven mineral reserve. |
propylitic alteration | Characteristic greenish color. Minerals include chlorite, actinolite and epidote. Typically contains the assemblage quartz–chlorite–carbonate |
proven mineral reserve | A proven mineral reserve is the economically mineable part of a measured mineral resource. For a proven mineral reserve, the qualified person has a high degree of confidence in the results obtained from the application of the modifying factors and in the estimates of tonnage and grade or quality. A proven mineral reserve can only result from conversion of a measured mineral resource. |
| | | | | | | | |
Date: February, 2022 | | Page 24-10 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
| | | | | |
Term | Definition |
qualified person | A qualified person is an individual who is a mineral industry professional with at least five years of relevant experience in the type of mineralization and type of deposit under consideration and in the specific type of activity that person is undertaking on behalf of the registrant; and an eligible member or licensee in good standing of a recognized professional organization at the time the technical report is prepared. For an organization to be a recognized professional organization, it must: (A) Be either: (1) An organization recognized within the mining industry as a reputable professional association, or (2) A board authorized by U.S. federal, state or foreign statute to regulate professionals in the mining, geoscience or related field; (B) Admit eligible members primarily on the basis of their academic qualifications and experience; (C) Establish and require compliance with professional standards of competence and ethics; (D) Require or encourage continuing professional development; (E) Have and apply disciplinary powers, including the power to suspend or expel a member regardless of where the member practices or resides; and; (F) Provide a public list of members in good standing. |
raise | A vertical or inclined underground working that has been excavated from the bottom upward |
reclamation | The restoration of a site after mining or exploration activity is completed. |
refining | A high temperature process in which impure metal is reacted with flux to reduce the impurities. The metal is collected in a molten layer and the impurities in a slag layer. Refining results in the production of a marketable material. |
refractory | Gold mineralization normally requiring more sophisticated processing technology for extraction, such as roasting or autoclaving under pressure. |
resistivity | Observation of electric fields caused by current introduced into the ground as a means of studying earth resistivity in geophysical exploration. Resistivity is the property of a material that resists the flow of electrical current |
roasting | A high temperature oxidation process for refractory ores or concentrates. The material is reacted with air (possibly enriched with oxygen) to convert sulfur in sulfides to sulfur dioxide. Other constituents in ore (e.g. C, Fe) are also oxidized. The resulting calcine can then be leached with cyanide, resulting in economic gold recoveries. |
rock quality designation (RQD) | A measure of the competency of a rock, determined by the number of fractures in a given length of drill core. For example, a friable ore will have many fractures and a low RQD. |
royalty | An amount of money paid at regular intervals by the lessee or operator of an exploration or mining property to the owner of the ground. Generally based on a specific amount per tonne or a percentage of the total production or profits. Also, the fee paid for the right to use a patented process. |
run-of-mine (ROM) | Rehandle where the raw mine ore material is fed into the processing plant’s system, usually the crusher. This is where material that is not direct feed from the mine is stockpiled for later feeding. Run-of-mine relates to the rehandle being for any mine material, regardless of source, before entry into the processing plant’s system. |
semi-autogenous grinding (SAG) | A method of grinding rock into fine powder whereby the grinding media consists of larger chunks of rocks and steel balls. |
| | | | | | | | |
Date: February, 2022 | | Page 24-11 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
| | | | | |
Term | Definition |
shaft | A vertical or inclined excavation for the purpose of opening and servicing a mine. It is usually equipped with a hoist at the top, which lowers and raises a conveyance for handling men and material |
specific gravity | The weight of a substance compared with the weight of an equal volume of pure water at 4°C. |
stope | An excavation in a mine, other than development workings, made for the purpose of extracting ore. |
strike length | The horizontal distance along the long axis of a structural surface, rock unit, mineral deposit or geochemical anomaly. |
tailings | Material rejected from a mill after the recoverable valuable minerals have been extracted. |
tunnel | A horizontal underground passage that is open at both ends; the term is loosely applied in many cases to an adit, which is open at only one end |
underhand drift and fill | The orebody is initially mined using a horizontal slice. The mined-out slice is then backfilled to provide additional support for the country rock surrounding the stope. The backfilled material forms the roof for executing the next, lower slice. In effect, in underhand cut-and-fill, the ore lies underneath the working area and the roof is backfill. |
uniaxial compressive strength | A measure of the strength of a rock, which can be determined through laboratory testing, and used both for predicting ground stability underground, and the relative difficulty of crushing. |
triaxial compressive strength | A test for the compressive strength in all directions of a rock or soil sample |
| | | | | | | | |
Date: February, 2022 | | Page 24-12 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
25.0 RELIANCE ON INFORMATION PROVIDED BY THE REGISTRANT
25.1 Introduction
The QP relied upon Barrick Gold Corporation, as the operator of NGM for the information used in the areas noted in the following sub-sections.
The NGM joint venture is governed pursuant to an operating agreement entered into on July 1, 2019 between Barrick and the registrant and their wholly-owned subsidiaries party thereto (JV Agreement). Under the terms of the JV Agreement, the registrant holds a 38.5% economic interest and Barrick holds a 61.5% economic interest in NGM. Barrick operates NGM with overall management responsibility and is subject to the supervision and direction of NGM’s Board of Managers, which is comprised of three managers appointed by the Operator and two managers appointed by the registrant. Outside of certain prescribed matters, decisions of the Board of Managers will be determined by a majority vote. The registrant also has representatives on the joint venture’s advisory committees, including its advisory technical, finance and exploration committees. The QP does not serve on the Board of Managers or the advisory committees. Given that the registrant does not have a majority interest, does not operate NGM and has more limited access, the registrant is required to rely upon Barrick for information.
The QP considers it reasonable to rely upon Barrick for the information identified in those sub-sections, for the following reasons:
•Barrick has held overall management and operational responsibility of NGM since July 2019;
•The JV Agreement requires Barrick to provide the registrant with reports of mineral reserves and resources sufficient to comply with securities laws and any other technical information reasonably requested by the registrant to permit it to comply with the reporting and disclosure obligations, as well as financial information, project and budget reports, certain guidance estimates, and other reports;
•The registrant has employed industry professionals with expertise to review the annual reserve and resource information provided by Barrick, and employs individuals with considerable experience in each of these areas listed in the following sub-sections who have also reviewed the information provided by Barrick;
•Like the registrant, Barrick has considerable experience in each of these areas and has employed industry professionals with expertise in the areas listed in the following sub-sections;
•Both the registrant and Barrick have formal systems of oversight and governance over these activities.
25.2 Macroeconomic Trends
•Information relating to inflation, interest rates, discount rates, exchange rates, and taxes was obtained from Barrick.
| | | | | | | | |
Date: February, 2022 | | Page 25-1 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
This information is used in the economic analysis in Chapter 19. It supports the assessment of reasonable prospects for economic extraction of the mineral resource estimates in Chapter 11, and inputs to the determination of economic viability of the mineral reserve estimates in Chapter 12.
25.3 Markets
•Information relating to market studies/markets for product, market entry strategies, marketing and sales contracts, product valuation, product specifications, refining and treatment charges, transportation costs, agency relationships, material contracts (e.g., mining, concentrating, smelting, refining, transportation, handling, hedging arrangements, and forward sales contracts), and contract status (in place, renewals), was obtained from Barrick.
This information is used in the economic analysis in Chapter 19. It supports the assessment of reasonable prospects for economic extraction of the mineral resource estimates in Chapter 11, and inputs to the determination of economic viability of the mineral reserve estimates in Chapter 12.
25.4 Legal Matters
•Information relating to the corporate ownership interest, the mineral tenure (concessions, payments to retain property rights, obligations to meet expenditure/reporting of work conducted), surface rights, water rights (water take allowances), royalties, encumbrances, easements and rights-of-way, violations, and fines, permitting requirements, and the ability to maintain and renew permits was obtained from Barrick.
This information is used in support of the property description and ownership information in Chapter 3, the permitting and mine closure descriptions in Chapter 17, and the economic analysis in Chapter 19. It supports the reasonable prospects of economic extraction for the mineral resource estimates in Chapter 11, and the assumptions used in demonstrating economic viability of the mineral reserve estimates in Chapter 12.
25.5 Environmental Matters
•Information relating to baseline and supporting studies for environmental permitting, and monitoring requirements, ability to maintain and renew permits, emissions controls, closure planning, closure and reclamation bonding and bonding requirements, sustainability accommodations, and monitoring for and compliance with requirements relating to protected areas and protected species was obtained from Barrick.
This information is used when discussing property ownership information in Chapter 3, the permitting and closure discussions in Chapter 17, and the economic analysis in Chapter 19. It supports the reasonable prospects of economic extraction for the mineral resource estimates in Chapter 11, and the assumptions used in demonstrating economic viability of the mineral reserve estimates in Chapter 12.
| | | | | | | | |
Date: February, 2022 | | Page 25-2 |
| | | | | |
Nevada Gold Mines Joint Venture Nevada Operations Technical Report Summary | |
| |
25.6 Stakeholder Accommodations
•Information relating to social and stakeholder baseline and supporting studies, hiring and training policies for workforce from local communities, partnerships with stakeholders (including national, regional, and state mining associations; trade organizations; fishing organizations; state and local chambers of commerce; economic development organizations; non-government organizations; and, state and federal governments), and the community relations plan was obtained from Barrick.
This information is used in the social and community discussions in Chapter 17, and the economic analysis in Chapter 19. It supports the reasonable prospects of economic extraction for the mineral resource estimates in Chapter 11, and the assumptions used in demonstrating economic viability of the mineral reserve estimates in Chapter 12.
25.7 Governmental Factors
•Information relating to taxation and royalty considerations, monitoring requirements and monitoring frequency, bonding requirements, violations, and fines was obtained from Barrick.
This information is used in the discussion on royalties and property encumbrances in Chapter 3, the monitoring, permitting and closure discussions in Chapter 17, and the economic analysis in Chapter 19. It supports the reasonable prospects of economic extraction for the mineral resource estimates in Chapter 11, and the assumptions used in demonstrating economic viability of the mineral reserve estimates in Chapter 12.
| | | | | | | | |
Date: February, 2022 | | Page 25-3 |