Overview
| Stage | Construction |
| Mine Type | Underground |
| Commodities |
|
| Mining Method |
- Drift & Fill
- Cut & Fill
- Paste backfill
|
| Mine Life | 9 years (as of Jan 1, 2020) |
Black Butte Copper is one of the highest-grade copper deposits being developed in the world.
Project permitting for mining of the Johnny Lee Deposit at Black Butte was completed in April 2020, with the Montana Department of Environmental Quality (MT DEQ) releasing the Final EIS on 13 March 2020 and issuing a positive Record of Decision to grant a Mine Operating Permit on 9 April 2020. The MT DEQ issued the final permit on 17 August 2020, and Sandfire initiated Phase I construction.
A legal challenge was filed to the MT DEQ Record of Decision on 4 June 2020, in the 14th Judicial Court in Meagher County, Montana, against the MT DEQ and Sandfire America’s wholly owned subsidiary, Tintina Montana Inc. On April 8, 2022, Montana district court ruling found in favour of the plaintiffs which stopped further construction. Sandfire America and the MT DEQ appealed the ruling to the Montana Supreme Court and Oral Arguments were heard on 21 June 2023. A decision on the case is pending. |
Source:
p. 87,72
Sandfire holds an 87% interest, via Canadian listed company Sandfire Resources America Inc., in the high grade Black Butte Copper Project.
Contractors
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Summary:
The majority of the Project area is underlain by gentle to moderately southward-dipping rocks of the Belt Supergroup. The Belt Supergroup lithofacies are juxtaposed against gently south-dipping Cambrian sedimentary rocks along the VVFZ. To the north of the Project area, Belt Supergroup rocks are also exposed, below the basal Cambrian unconformity. Intermediate to mafic, Early Tertiary intrusive dykes and sills occur within the Belt Supergroup. Late Tertiary sedimentary lithofacies unconformably overlie all other units in the area.
Potentially economic Cu mineralization has been identified in the Newland Formation at the UCZ and the LCZ. The mineralization in both of these deposits is largely hosted by massive sulphide units referred to as the USZ and LSZ, respectively. Although not included in the MOP application, Cu mineralization also occurs at Lowry situated 3 km SE of the Johnny Lee deposit (Figure 7.2). Mineralization at Lowry is hosted by the LSZ and the MSZ. In order to discriminate between Johnny Lee and Lowry, the MSZ and LSZ at Lowry are herein referred to as Lowry Middle Sulphide Zone (LMSZ) and Lowry Lower Sulphide Zone (LLSZ). Mineralization at Lowry that occurs in these zones is referred to as the Lowry Middle Copper Zone (LMCZ) and Lowry Lower Copper Zone (LLCZ).
Johnny Lee Lower Copper Zone
The LCZ occurs at depths of 340 to 520 m below surface, strikes approximately EW and dips at 15° to 30° to the south. Mineralization in the LCZ i ........
Mining Methods
- Drift & Fill
- Cut & Fill
- Paste backfill
Summary:
Upper Copper Zone Mining Methods
The UCZ is a flat dipping deposit with multiple parallel lenses. It will be entirely extracted using DF mining methods.
The DF panels will be setup with two parallel access drifts spaced 60 - 90 m apart where possible. Primary ore drifts spaced 15 m apart will be developed from one access drift to within 5 m of the second access drift. Once the drift has completed mining, all the services will be stripped from the drift and a barricade will be built at the access. Paste and breather holes will then be drilled from the second access drift through the pillar and paste fill will be placed in the drift.
Once two adjacent primary drifts have cured, a secondary ore drift will be driven to the end of the panel in the middle of the two cured drifts. This drift will be 5 m wide with two 2.5 m wide pillars on either side. These pillars will then be extracted by drilling unsupported slashes up against the paste and mucking out on remote control. Once the secondary drift has been mined out, a barricade will be built, and the secondary drift will be filled using the same process as the primary drifts.
Once an entire panel has been mined out and both access drifts are paste filled, the pillar is mined out and then paste filled.
In areas where there is no second access to fill from, the same general sequence will be followed. However, the primary drifts will be located 10 m apart and the secondary drifts will ........
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Flow Sheet:
Summary:
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Projected Production:
| Commodity | Units | Avg. Annual |
|
Copper
|
kt
| 120 |
All production numbers are expressed as concentrate.
Operational Metrics:
| Metrics | |
|
Daily production capacity
| 400 t of copper concentrate * |
|
Annual ore mining rate
| 1.2 Mt * |
|
Annual production capacity
| 122 kt of copper concentrate * |
|
Annual processing capacity
| 1,204,500 t * |
|
Waste tonnes, LOM
| 0.88 Mt * |
|
Ore tonnes mined, LOM
| 8.8 Mt * |
|
Total tonnes mined, LOM
| 9.68 Mt * |
* According to 2020 study.
Reserves at October 19, 2020:
Mineral Reserves were estimated using a NSR cut-off value of $70/t.
Mineral Resources are reported using a cut-off grade of 1.00% recoverable Cu.
| Category | Tonnage | Commodity | Grade | Contained Metal |
|
Proven
|
1,998,000 t
|
Copper
|
3 %
|
60,700 t
|
|
Probable
|
6,804,000 t
|
Copper
|
2.4 %
|
165,400 t
|
|
Proven & Probable
|
8,802,000 t
|
Copper
|
2.6 %
|
226,100 t
|
|
Measured
|
2 Mt
|
Copper
|
3.5 %
|
69.1 kt
|
|
Indicated
|
8.9 Mt
|
Copper
|
2.7 %
|
241.8 kt
|
|
Measured & Indicated
|
10.9 Mt
|
Copper
|
2.9 %
|
310.9 kt
|
|
Inferred
|
2.7 Mt
|
Copper
|
3 %
|
79.7 kt
|
Pipelines and Water Supply
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