United States

Bald Mountain Mine

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Overview

Mine TypeOpen Pit
Commodities
  • Gold
Mining Method
  • Truck & Shovel / Loader
Production Start1981
Mine Life2024
ShapshotBald Mountain is the largest mine site by area in the U.S. It stretches 40 km north to south and 15 km east to west and is divided in three zones: North Zone, South Zone and JV Zone.

Owners

SourceSource
CompanyInterestOwnership
Kinross Gold Corp. 100 % Indirect
KG Mining (Bald Mountain) Inc. (operator) 100 % Direct
The Bald Mountain mine is owned and operated by Kinross’ wholly-owned subsidiary KG Mining (Bald Mountain) Inc. (“KGBMI”).

Deposit type

  • Sediment-hosted

Summary:

The project area is located approximately 65 miles northwest of Ely, Nevada, in an area of uplifted Paleozoic through Tertiary rocks. The area is part of a corridor of northwest-southeast directed Tertiary extension in the Basin and Range province of Nevada. The study area is characterized by two north-trending uplifted blocks, the Bald Mountain-Buck Mountain Ridge on the west and Alligator Ridge on the east, separated by a fault valley that encompasses Mooney Basin, the Alligator Ridge deposits, and the Yankee and Vantage deposits.

The Bald Mountain Mining District falls along the southeastern extension of the Carlin trend (Nutt et al.2000). The district contains two separate but adjacent mineral trends: 1) the northwest-southeast Bida trend that parallels the Carlin trend; and 2) the Yankee-Alligator Ridge-Mooney Basin trend that follows the north-northeast trend of the structural basin between the Bald Mountain-Buck Mountain Ridge and Alligator Ridge. The geology of the district is quite complex and consists of a variety of reactivated folds and faults that serve to localize the gold deposits.

The Bida trend is a northwest-southeast structural trend that encompasses the Bald Mountain stock and gold deposits associated with the intrusion of this Jurassic quartz monzonite stock (Nutt et al. 2000). The gold deposits are disseminated along high-angle structures in the Jurassic stock and in the adjacent Cambrian and Ordovician sedimentary rocks. Gold is associated with pyrite, arsenopyrite, marcasite, and argillic alteration. Mineralized limestones have garnet-epidote skarns with associated tungsten, molybdenum, and zinc (Nutt et al. 2000). The deposits were formed at a depth of 3 to 6 km from magmatic fluids associated with the intrusion of the Bald Mountain stock during the Jurassic. The RBM deposit is a higher level deposit in Mississippian clastic sedimentary rocks. Productive ore zones are found at the contact between the Eldorado Limestone-Geddes Limestone and the Secret Canyon Shale, along the contact between the Hamburg Limestone and the Dunderberg Shale, and in the upper part of the Pogonip Group. Uplift of the Bald Mountain area during the Tertiary exposed these gold deposits to erosion and set the stage for discovery and development of gold resources within the Bald Mountain Mining District.

The Mooney Basin-Alligator Ridge-Yankee trend consists of gold deposits that are typical of Carlin-type gold deposits and consist of disseminated gold associated with jasperoid, decalcification, sericite, and clay alteration. Gold is found with pyrite, sphalerite, arsenopyrite, marcasite, realgar, orpiment, stibnite, and barite. The deposits are often associated with reactivated Mesozoic faults and fractures, are localized along the edges of folds, and are stratabound in the Pilot Shale in a zone 100 to 200 feet in thickness (Nutt et al. 2000). Most deposits are associated with jasperoid in the underlying Guilmette Formation. These deposits are Eocene-Oligocene (Tertiary) in age and formed in a shallow, epithermal hot spring environment (Nutt et al. 2000) along a Basin and Range structural basin. Thus, these deposits are considerably younger than the gold deposits with the BMM area.

Reserves

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Mining Methods

  • Truck & Shovel / Loader

Summary:

The Bald Mountain operation is an open pit mining operation with production from a number of different pits. The two main deposits (Saga and LBM) represent approximately 76% of the known reserves. Bald Mountain includes several other deposits scattered over the property, and three ROM heap leach pads (Bald Mountain, Mooney and Vantage).

Bald Mountain mine is mined using standard open pit methods including drilling, blasting and loading into haul trucks. Typical bench heights are 25 to 40 feet high and of variable width. Overall pit wall slope angles range from 30 to 55 degrees. Blasted ore and waste rock are loaded into haul trucks by front-end loaders or electric and hydraulic shovels. Ore is hauled to the run-of-mine (ROM) leach pad.

Comminution

Crushers and Mills

Milling equipment has not been reported.

Processing

  • ROM/dump leach
  • Carbon in column (CIC)
  • Carbon adsorption
  • Cyanide (reagent)

Summary:

Bald Mountain recovers gold using multiple ROM heap leach pads. Gold is extracted from the ore with a cyanide solution and collected on activated carbon in CIC plants. Loaded carbon is shipped off-site for further processing and ultimate gold refining. The mining recovery is high because the ore blocks are large compared to the selective mining unit, and close to all of the material outlined as ore in the grade control process is mined. Selectivity of the ore mining is minimal due to the low cut-off grade and the fact that the grade control outlines large blocks of ore-grade material for mining. Whenever possible, ore blocks are oriented square to the dig direction – minimizing ore loss and dilution.

The heap leach operations are divided into three areas: Bald, Mooney (North, South and Deep South), and Vantage. Vantage is the newest of the areas and became operational during the recertification period. The carbon-in-column (CIC) processing plants include: Process Plant 2, Mooney North Plant, Mooney South Plant, and the Vantage Plant. The Vantage Plant utilizes an innovative vertical CIC process. All operations noted here are within the North Operations Area (NOA) except for the Vantage Complex which is in the South Operations Area (SOA).

The Bald Mountain Mine Area includes:
• Process Area #1 which is no longer in operation. This consisted of a leach pad, five process ponds and a process building. The facilities have been decommissioned and the ponds backfilled. The area is currently under reclamation.
• Process Area #2 includes leach pads (Bald Leach Pad (previously pads 2 through 4) and Leach Pad 5), Pregnant Sump (PS1), Overflow Pond (POF1) and Secondary Pond (P4), two pregnant solution ponds (P5 and P6), Barren Pond (P7), Carbon-in-Column (CIC) process plant and cyanide offloading facility. However, the leach pads are not being actively leached; cyanide has not been added to the leach pads in over 12 months. The leach pads continue to drain down and the CIC process is still operational.

The Mooney Basin Area includes three process areas:
• North Area Facility, comprising a leach pad (Original Pad and Expansion Pads I, II, and III), two process solution ponds, a storm/event pond, Carbon-in-Column (CIC) process plant and cyanide off-loading facility;
• South Area Facility, comprising Leach Pad 4, a process solution pond, a storm/event pond, a solution collection tank, CIC plant and cyanide off-loading facility.
• Deep South Area Facility, comprising Leach Pads 5 and 6, a process solution pond, one storm/event pond, and a solution collection tank. Pregnant solution from this facility is piped to the South Area CIC plant for processing.

Originally, the Mooney North and Mooney South Area facilities operated independently. Pregnant and barren solution lines were constructed that connected these facilities, allowing solution to be pumped between them as needed.

The construction of the Vantage Complex began in Quarter 1 2018. The Vantage Complex is in the South Operations Area, was commissioned in 2019, and consists of:
• A leach pad, a solution collection tank, a process solution pond, a storm/event pond, CIC process plant, two cyanide storage tanks, and a cyanide off-loading area.

Recoveries & Grades:

CommodityParameter2022202120202019201820172016
Gold Equivalent Head Grade, g/t 0.510.510.510.420.430.80.64

Production

CommodityUnits2022202120202019201820172016
Gold Equivalent oz 000000000000000000000000284,646282,715130,144
Gold koz

Operational metrics

Metrics202220212020201920182017
Ore tonnes mined 15,969 kt19,063 kt18,303 kt15,806 kt24,477 kt21,615 kt
Waste 38,318,422 t38,436,154 t53,310,746 t55,892,129 t43,686,000 t
Tonnes processed 15,924 kt19,063 kt18,303 kt16,475 kt23,654 kt21,615 kt
Daily mining capacity
Stripping / waste ratio

Production Costs

CommodityUnits202220212020201920182017
Cash costs (sold) Gold Equivalent USD 000 000 000 768 / oz   547 / oz   642 / oz  
Cash costs Gold USD
All-in sustaining costs (AISC) Gold USD

Financials

Units202220212020201920182017
Sustaining costs M USD 35.3  30.3  99.9  
Capital expenditures M USD 87.6  39  103.8   220.7   149.9   90.5  
Revenue M USD 386  352.1  330.5   249.2   403.9   331.5  
Operating Income M USD -5.6  -174.7  34.6   12.7   110.7   68.5  
Gross profit M USD 1.2  -165.8  46.3   33.1   130.1   79.1  

Heavy Mobile Equipment

Ref. Date: June 29, 2016

SourceSource
HME TypeModelQuantity
Shovel P&H 2800 XPC 2
Shovel Hitachi EX5500 1
Shovel Hitachi EX5600 1
Shovel Hitachi EX3600 1
Truck (haul) Komatsu 830E-AC 23
Truck (haul) Caterpillar 785 9
Truck (haul) Komatsu 830E D/C 5

Personnel

Mine Management

Source Source
Job TitleNameProfileRef. Date
Chief Metallurgist Rodrigo Andrade LinkedIn Dec 15, 2023
Manager Continuous Improvement Vicente Ramirez LinkedIn Dec 15, 2023
Operations Manager Dale Thompson LinkedIn Dec 15, 2023
Process Maintenance Superintendent Mark Wilson LinkedIn Dec 15, 2023
Sr. Production Geologist Eric Herth LinkedIn Dec 15, 2023
Technical Services Manager Cristian Gonzalez LinkedIn Dec 15, 2023
VP and General Manager Joseph Kemp LinkedIn Dec 15, 2023

EmployeesContractorsTotal WorkforceYear
592 167 759 2022
607 222 829 2021
591 194 785 2020
607 191 798 2019
578 499 1,077 2018
500 2016

Aerial view:

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