Overview
| Stage | Permitting |
| Mine Type | Open Pit |
| Commodities |
|
| Mining Method |
|
| Production Start | ...  |
| Mine Life | 13 years (as of Jan 1, 2020) |
Completion of the feasibility study (“FS”) for the North Bullfrog Project is anticipated during the second half of 2023. The FS is proposing an open- pit mining alternative utilising both gravity milling and heap leaching for ore processing. Results from recent Mineral Resource conversion drilling are being incorporated into an update of the Mineral Resource model. This model will be the basis for the final optimisation of the FS. Permitting processes are underway for the North Bullfrog Project and environmental baseline studies are being reviewed by the agencies for completeness. Federal and state permitting processes are expected to formally commence during the first quarter of 2024. |
Source:
p. 127
The North Bullfrog project is an indirect wholly owned and managed by AngloGold Ashanti.
Contractors
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Deposit Type
- Epithermal
- Vein / narrow vein
- Volcanic hosted
Summary:
Geology
The project lays within the Walker Lane mineral belt and the Southwestern Nevada Volcanic Field (SWNVF). The regional stratigraphy includes a basement of Late Proterozoic to Late Paleozoic metamorphic and sedimentary rocks. Basement rocks are overlain by a thick pile of Miocene volcanic and lesser sedimentary rocks of the SWNVF, ranging in age from approximately 7.5 to 15Ma. The pre-Tertiary rocks exhibit large-scale folding and thrust faulting, having been subjected to compressional deformation associated with multiple preTertiary orogenic events. The stratigraphy of the SWNVF is dominated by ash flow tuff sheets erupted from a cluster of nested calderas known as the Timber Mountain Caldera Complex. The southwestern edge of the caldera complex lies approximately 10km east of the North Bullfrog project. The stratigraphy of the SWNVF includes voluminous ash flow tuff sheets, smaller volume lava flows, shallow intrusive bodies, and lesser sedimentary rocks.
Deposit type
Miocene rhyolitic volcanic tuff and flows host the lowsulphidation epithermal deposits at North Bullfrog. Steeply dipping structures contain high-grade gold and silver epithermal vein mineralisation and occur within pervasively quartz-adularia altered volcanic rocks which also host broad disseminated lowgrade mineralisation. Mineralisation at North Bullfrog is typical of other low-sulphidation type gold systems in and around the Walker Lane trend in Nevada.
Mineralisation style
Gold mineralisation at N ........
Summary:
The North Bullfrog project is a combination of four mineralised deposits comprised of YellowJacket, Sierra Blanca, Jolly Jane and Mayflower. The YellowJacket deposit is a continuous high-grade vein within the moderate-grade stockwork mineralisation. The other three deposits are low to medium-grade.
The proposed mining method is conventional open pit mining. Ore and waste are drilled and blasted, then loaded into 150t payload haul trucks with approximately 20m3 bucket capacity wheel loaders. The loading and haulage fleet will be supported by track dozers, motor graders and water trucks. Waste is hauled to waste rock management facilities near each pit. Mill ore will be hauled to the mill ore stockpile while ROM ore will be hauled and placed directly on the heap leach pad. Mill tailings will be hauled and placed directly on the heap leach pad and mixed into the ROM ore by dozing. The proposed mining operation is owner-operated equipment.
Pit slope designs have been based on an overall 50-degree inter-ramp angle. A pit slope analysis was completed by Knight Piésold and Company in May 2020. This inter-ramp angle was consistent with analyses conducted for the Jolly Jane open pit (Engineering Analytics, 2013a) and the Mayflower open pit (Engineering Analytics, 2013b).
Geotechnical Criteria for Mine Design:
- Inter-Ramp Angles - 58°;
- Face Angles - 80°;
- Catch Bench Berm - 8 m;
- Catch Bench Vertical Spacing - 20 m;
- Road Widths (Including Berm) - 32 m;
- Road Grade - 10%.
Th ........
Source:
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Flow Sheet:
Summary:
- subscription is required.
Projected Production:
| Commodity | Units | Avg. Annual | LOM |
|
Gold
|
koz
| 112 | 1,461 |
|
Silver
|
koz
| | ...... |
All production numbers are expressed as payable metal.
Operational Metrics:
| Metrics | |
|
Daily mining rate
| 85 kt * |
|
Daily ore mining rate
| 43 kt * |
|
Daily processing capacity
| 46.4 kt * |
|
Annual production capacity
| 118 koz of gold metal in doré * |
|
Annual production capacity
| 264 koz of silver metal in doré * |
|
Stripping / waste ratio
| 0.96 * |
|
Waste tonnes, LOM
| 211.97 Mt * |
|
Ore tonnes mined, LOM
| 226.6 Mt * |
|
Total tonnes mined, LOM
| 433.43 Mt * |
|
Tonnes processed, LOM
| 221.46 Mt * |
* According to 2020 study.
Reserves at December 31, 2022:
The Mineral Resources was estimated by ordinary kriging and constrained by pit optimisation at a gold price of $1,750/oz. The breakeven cut-offs are determined to be 0.17g/t for gravity mill material and 0.09g/t for heap leach material.
| Category | Tonnage | Commodity | Grade | Contained Metal |
|
Measured
|
28.71 Mt
|
Gold
|
0.24 g/t
|
0.22 M oz
|
|
Measured
|
28.71 Mt
|
Silver
|
0.92 g/t
|
0.85 M oz
|
|
Indicated
|
82.54 Mt
|
Gold
|
0.37 g/t
|
0.97 M oz
|
|
Indicated
|
82.54 Mt
|
Silver
|
1.59 g/t
|
4.22 M oz
|
|
Inferred
|
44.35 Mt
|
Gold
|
0.25 g/t
|
0.36 M oz
|
|
Inferred
|
44.35 Mt
|
Silver
|
0.63 g/t
|
0.9 M oz
|
|
Total Resource
|
155.6 Mt
|
Gold
|
0.31 g/t
|
1.54 M oz
|
|
Total Resource
|
155.6 Mt
|
Silver
|
1.19 g/t
|
5.96 M oz
|
Source:
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Corporate Filings & Presentations:
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