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United States
East Boulder Mine (Stillwater Operation)

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 Location:
126 km W from Billings, Montana, United States

  Regional Office:
26 West Dry Creek Circle Suite 400
Littleton
Colorado, United States
80120
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WebsiteWeb
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  • Overview
  • Owners
  • Geology
  • Mining
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  • Personnel
  • Filings & News

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Overview

StageProduction
Mine TypeUnderground
Commodities
  • Palladium
  • Platinum
Mining Method
  • Ramp & Fill
  • Overhand Cut & Fill
  • Raiseboring
  • Sub-level stoping
  • Alimak
  • Hydraulic backfill
Production Start...
Mine Life2061


Owners

Source: p. 59
CompanyInterestOwnership
Stillwater Mining Company Inc. (operator) 100 % Direct
Sibanye-Stillwater Ltd. 100 % Indirect
Ownership Tree

Contractors

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Deposit Type

  • Magmatic


Summary:

The Stillwater Complex is a layered ultramafic to mafic igneous complex formed by the gradual cooling of an enormous subterranean intrusion. In such intrusions, the gradual cooling leads to the formation of layers of crystals with similar geochemical properties. Some of these layers are essentially monomineralic (anorthosites composed of high-calcium plagioclase), while others have additional minerals such as troctolites, which contain both high-calcium plagioclase and olivine. The layering is very distinct and resembles the layering of sedimentary rocks even though the rocks of the complex are igneous. These layers form over extremely large areas. The fact of this layering is critically important to understanding the deposition of the palladium- and platinum- bearing minerals in the J-M Reef.

The J-M Reef is recognized by the presence of chalcopyrite, pyrrhotite, pentlandite, and, rarely, pyrite within the reef package. Other base-metal sulfides have been identified, but their presence is subordinate. The platinum group minerals can rarely be recognized with a hand lens. SMC (2001) reported that platinum occurs primarily (67%) as sulfide, 25% as the metal alloy, isoferroplatinum, and 8% as the telluride, moncheite. Palladium occurs primarily (80%) as a solid-solution in pentlandite, 15% as sulfides, and 5% in the telluride, moncheite. The platinum:palladium ratio averages 1:3.5 in-situ at the Stillwater Mine, except for the Dow (Upper West) area of the mine, wher ........


Mining Methods

  • Ramp & Fill
  • Overhand Cut & Fill
  • Raiseboring
  • Sub-level stoping
  • Alimak
  • Hydraulic backfill


Summary:

The East Boulder operation is accessed via twin 5,800m long decline tunnels. Key infrastructure includes the mining operations and ancillary buildings that contain the concentrator, workshop, warehouse, changing facilities, twin tunnels to access mine, sand plant, water treatment, storage facilities and offices. The two principal mining methods are: • mechanised ramp and fill (both overhand and underhand) (80% – 90%) • sub-level extraction by long hole, open stoping with hydraulic backfilling (10% – 20%)


Crushing and Grinding


Processing

Source: Subscription required

Summary:

- subscription is required.


Production:

CommodityProductUnits2021202020192018201720162015
2E (Pt, Pd) Metal in concentrate koz  ......  Subscription required  ......  Subscription required  ......  Subscription required228148218201
Palladium Metal in concentrate koz  ......  Subscription required  ......  Subscription required
Platinum Metal in concentrate koz  ......  Subscription required  ......  Subscription required
2E (Pt, Pd) Concentrate kt 13,78213,347
Subscription required - Subscription is required.

Operational Metrics:

Metrics202020192018201720162015
Daily milling rate  ......  Subscription required1,600 t
Daily milling capacity  ......  Subscription required1,800 t1,800 t1,600 t2,000 tons2,000 tons
Annual milling rate  ......  Subscription required608 kt
Tonnes milled  ......  Subscription required656 k tons583 k tons
Daily mining rate  ......  Subscription required1,755 tons1,589 tons
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Reserves at December 31, 2021:
Mineral Reserve cut-off grade is 1.7 g/t 2E.

CategoryTonnage CommodityGradeContained Metal
Proven 3.5 Mt 2E (Pt, Pd) 13 g/t 1.5 M oz
Probable 24.3 Mt 2E (Pt, Pd) 12.3 g/t 9.6 M oz
Proven & Probable 27.9 Mt 2E (Pt, Pd) 12.4 g/t 11.1 M oz
Measured 18.1 Mt 2E (Pt, Pd) 13.6 g/t 13.6 M oz
Indicated 27.8 Mt 2E (Pt, Pd) 13.3 g/t 11.8 M oz
Measured & Indicated 45.9 Mt 2E (Pt, Pd) 13.4 g/t 19.8 M oz
Inferred 52.2 Mt 2E (Pt, Pd) 12.3 g/t 20.6 M oz

Commodity Production Costs:

CommodityUnits20162015
Total cash costs 2E (Pt, Pd) USD 441 / oz†   508 / oz†  
† Net of By-Product.

Operating Costs:

Units20162015
Total operating costs ($/ton milled) USD 147175

Financials:

Units20212016
Sustaining costs M USD 16.7  
Book Value M USD  ......  Subscription required
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Heavy Mobile Equipment:

Mine Management:

Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required Jul 19, 2022
....................... Subscription required ....................... Subscription required Subscription required Jul 19, 2022
....................... Subscription required ....................... Subscription required Subscription required Jul 19, 2022
....................... Subscription required ....................... Subscription required Subscription required Jul 19, 2022
....................... Subscription required ....................... Subscription required Subscription required Jul 19, 2022
....................... Subscription required ....................... Subscription required Subscription required Jul 19, 2022
Subscription required - Subscription is required.

Staff:

EmployeesContractorsTotal WorkforceYear
Subscription required Subscription required Subscription required 2021
Subscription required Subscription required Subscription required 2020
Subscription required Subscription required Subscription required 2019
Subscription required Subscription required Subscription required 2018
Subscription required Subscription required Subscription required 2017
Subscription required 2016
Subscription required 2015

Corporate Filings & Presentations:

DocumentYear
................................... Subscription required 2021
................................... Subscription required 2020
................................... Subscription required 2020
................................... Subscription required 2019
................................... Subscription required 2019
................................... Subscription required 2019
Form 20-F 2018
Integrated Report 2018
Year-end Mineral Reserves 2018
Form 20-F 2017
Year-end Mineral Reserves 2017
Form 10-K 2016
Form 10-K 2015
Technical Report 2011
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