Overview
Stage | Preliminary Economic Assessment |
Mine Type | Open Pit |
Commodities |
|
Mining Method |
|
Processing |
- Crush-and-stack plant
- Filter press plant
- Smelting
- Carbon re-activation kiln
- Dewatering
- Heap leach
- Carbon in column (CIC)
- Carbon adsorption-desorption-recovery (ADR)
- Elution
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
|
Mine Life | 8.5 years (as of Jan 1, 2020) |
Source:
p. 12
Summary:
The Project lies within a broad region of relatively young (15Ma) volcanic rocks predominantly made up of welded flow banded rhyolite units interlayered with unwelded bedded tuffs (Bussey, 1996). The volcanic host rocks and subsequent hydrothermal activity associated with this volcanism is interpreted to be the cause of the gold mineralisation and associated large scale alteration observed at Bells.
Bells has the typical geological signature of a low-sulphidation epithermal deposit which formed close to the surface. Throughout north-west Nevada, there exists other similar epithermal gold deposits (such as Midas and Sleeper) which have a documented age similar to Bells and are interpreted to be related to volcanism and hydrothermal activity from the Yellowstone “Hot Spot” (Saunders et. al., 2008).
Bells is defined by a large area of alteration which has affected the volcanic host rocks and it is this alteration which initially attracted explorers to the project area. The gold mineralisation within this large alteration feature is predominantly dispersed horizontally along favourable and relatively flat lying host rocks. The current Mineral Resource estimate is based on the style of mineralisation that was the initial focus of exploration and mining. This style of mineralisation is dominated by relatively flat lying and dispersed low-grade gold mineralisation.
Summary:
The Bells Deposit is shallow, flat lying and amenable to conventional open pit mining methods. The resource model was converted to a regularised 5m x 5m x 5m block mining model which was considered a suitable selective mining unit size for this style of deposit. This resulted in an overall dilution of the Mineral Resource model of approximately 5.8%. In the mining model, the regularised blocks were considered either ore or waste.
The Bells deposit is planned to be mined using conventional open pit mining methods in seven stages. The mining operation will be on dayshift only with a roster of two production crews on a 4-days on and 4-days off, 12 hours per day.
Open pit mining will be by diesel-powered equipment, utilising a combination of one 40 tonne rotary blasthole rig drilling 200mm diameter blastholes, one 12m3 hydraulic backhoe excavator, and four, 91- tonne capacity trucks to handle ore and waste. The mining fleet has enough capacity to move up to approximately 6Mtpa on dayshift. Support equipment composed of a grader, track dozers and water truck will aid in the mining. Ore will be hauled downhill to the crushing area for stockpiling before being rehandled for primary crushing. Initially, waste rock will be stored in the waste rock dumps close to the pit to reduce haulage costs. After year one, most of the waste will be backfilled into the pit to reduce haulage costs and surface disturbance.
The final pit was designed using 10m benches, a bench face angle of 78° and an inter-ramp slope angle of 55° between a single bench-catch berm of 5m. Haul roads were designed to 15m widths for one-way traffic and 25m widths for two-way traffic. The final location of the ramps was optimised to reduce the overall pit slopes in areas where the pit slope was required to be less than 55°. The pit is approximately 900m wide by 900m long. The deepest portion of the pit is 135m below surface, however the average depth is less than 70m below surface. The pit is considered dry.
The mine plan was designed to deliver 3,000,000 tonnes of ore per year to the processing facility.
Flow Sheet:
Crusher / Mill Type | Model | Size | Power | Quantity |
Jaw crusher
|
|
|
|
1
|
Summary:
Over the life of the mine, ore will be delivered to the heap leach pad from the open pit and placed in the stockpile adjacent to the crushing plant. The ore will be fed to the crushing plant using a front-end loader, and will be crushed, agglomerated, then transported to the heap leach pad via an overland conveyor.
Processing
- Crush-and-stack plant
- Filter press plant
- Smelting
- Carbon re-activation kiln
- Dewatering
- Heap leach
- Carbon in column (CIC)
- Carbon adsorption-desorption-recovery (ADR)
- Elution
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
Flow Sheet:
Summary:
Precious metal recovery from the mine in this Scoping Study is through conventional heap leaching and adsorption, desorption, regeneration (ADR) technology for metal extraction from crushed and agglomerated ore using industry standard equipment. Processing will involve ore passing through a single stage of crushing, which will allow for belt conveyor stacking of the ore onto a heap leach pad. The processing facilities accommodate a leachable Mineral Resource of approximately 25Mt of ore at a gold grade of 0.50g/t and a process rate of 8,600tpd or 3Mtpa. The heap leach pad has been located and designed with expandability for a LOM production increase.
The ore will be stacked onto the heap using a radial stacker and then leached with a weak cyanide solution to extract the precious metal values. The gold will then be recovered from the pregnant solution in the carbon plant by adsorbing the dissolved gold onto activated carbon, which initially, will be bagged and transported off ........

Recoveries & Grades:
Commodity | Parameter | Avg. LOM |
Gold
|
Recovery Rate, %
| 80 |
Gold
|
Head Grade, g/t
| 0.5 |
Reserves at March 23, 2021:
Cut off grade is 0.17 g/t Au
Category | Tonnage | Commodity | Grade | Contained Metal |
Indicated
|
24 Mt
|
Gold
|
0.5 g/t
|
390 koz
|
Inferred
|
13 Mt
|
Gold
|
0.4 g/t
|
170 koz
|
Total Resource
|
37 Mt
|
Gold
|
0.47 g/t
|
560 koz
|
Mine Management:
Job Title | Name | Profile | Ref. Date |
.......................
|
.......................
|
|
Jun 23, 2021
|
- Subscription is required.
Staff:
Total Workforce | Year |
|
2020
|
Corporate Filings & Presentations:
Document | Year |
...................................
|
2021
|
...................................
|
2020
|
...................................
|
2020
|
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Aerial view:
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