Overview
Stage | Permitting |
Mine Type | Open Pit |
Commodities |
|
Mining Method |
|
Processing |
- Gravity separation
- Calcining
- Dry Screening
- Wet Screening
- Carbon re-activation kiln
- Smelting
- Dewatering
- Hydrochloric acid (reagent)
- Agitated tank (VAT) leaching
- Carbon in leach (CIL)
- Carbon adsorption-desorption-recovery (ADR)
- Elution
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
|
Mine Life | 9 years (as of Jan 1, 2020) |
Progress on the Definitive Feasibility Study (DFS) has continued, however COVID-19 related restrictions are limiting access to site for engineering and potential vendor inspections. |
Latest News | Regis plans golden future at McPhillamys January 28, 2021 |
Source:
p. 87
Summary:
The McPhillamys gold deposit lies along one of a series of north-south trending splays/horsetail structures that occur at the inflection of the Godolphin-Copperhania Fault Zone where the orientation changes from NNW-SSE to SSW-NNE. The splays are defined by strong shearing and faulting and continue to the south for over 6km. The deposit is hosted by dacite- rich volcaniclastic rocks of the Silurian-aged Anson formation which vary in composition from crystal tuffs to agglomeratic, matrix-supported accretions.
Gold mineralisation is associated with strongly sheared volcaniclastics with strong quartz- carbonate-sericite-pyritepyrrhotite alteration. The gold mineralisation trends roughly north-south over a strike distance of 900m and dips steeply east at 70º to 80º to the east.
Summary:
A conventional load and haul mining method has been selected for the development of the MGP. Open pit mining activities are expected to be conducted by an experienced third-party earthmoving contractor.
All mining is proposed to take place 24 hours per day, 7 days per week using conventional excavators and haul trucks as used in open pit gold mining operations world-wide. The mineralised ore profile will be mined in benches of between 2.5 and 5.0 metres for grade and selectivity considerations. The ore boundaries will be determined by grade control drilling.
Allowance has been made in the mining schedule to blast 70% of the oxide domain (excluding clay zone defined as free dig) and 100% of the transitional and fresh domains prior to load and haul of the material to the waste dumps, low grade stockpile or ROM.
The single open pit will be mined in two stages to assist in reducing total earthmoving production requirements and in particular the first two years of operation. Additional detailed scheduling will be required to further optimise material movement and manage the estimated 20 to 25% of Potentially Acid Forming (PAF) waste material contained within the pit.
Pit slope design parameters have been developed to a level of confidence suitable for DFS level design. Based on the structural and geotechnical interpretations, a range of likely controlling slope failure mechanisms have been proposed, from bench-scale up to inter-ramp and overall slope.
The overall open pit slope averages approximately 43.5o to 46.6 o depending on geotechnical domain. Oxide, transition and fresh rock types vary in overall pit slope angles according to geotechnical advice and how many haul road passes occur in any given zone.
Flow Sheet:
Crusher / Mill Type | Model | Size | Power | Quantity |
Gyratory crusher
|
|
|
|
1
|
Cone crusher
|
|
|
|
3
|
Ball mill
|
|
|
|
1
|
Regrind
|
|
|
|
1
|
Summary:
Ore from the open cut would be transported from the proposed open cut to the ROM Pad using haul trucks. The material would then be either direct tipped into the primary crusher hopper or stockpiled within the ROM Pad. Stockpiled ore would then be fed as required into the primary crusher hopper using a front-end loader.
The crushing circuit would comprise a primary crusher to reduce the size of the ROM ore from up to 800mm in diameter to less than 250mm. The primary crushed ore would then be directed to a series of screens and one or more secondary and tertiary crushers, to reduce the size of the ore particles to less than 20mm in size after which the crushed ore would be stockpiled on a crushed ore stockpile.
An under-stockpile conveyor would transport the ore to the grinding circuit. Lime would be added to the crushed ore on the conveyor prior to the grinding mill to elevate the pH within the CIL circuit. The crushed ore would then be combined with water in the grinding mill and the rotating action of the mill would reduce the ore particle size.
The ground ore slurry would then be passed through a hydrocyclone classification circuit where coarser particles would be separated and reintroduced to the grinding mill, whilst finer particles, approximately 150µm (0.15mm) or less, are directed to the gravity recovery circuit.
Processing
- Gravity separation
- Calcining
- Dry Screening
- Wet Screening
- Carbon re-activation kiln
- Smelting
- Dewatering
- Hydrochloric acid (reagent)
- Agitated tank (VAT) leaching
- Carbon in leach (CIL)
- Carbon adsorption-desorption-recovery (ADR)
- Elution
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
Flow Sheet:
Summary:
Ore material would be processed within a conventional carbon-in-leach (CIL) processing plant. The proposed processing plant would have a nominal throughput of approximately 7Mtpa. In summary, the processing operations would include the following:
- Stockpiling and blending of ore at the ROM Pad.
- Crushing, screening and stockpiling of the ore.
- Grinding and gravity recovery.
- Leaching of the gold from the ore using conventional carbon-in-leach (CIL) processing.
- Recovery of the gold from the leach solution.
- Tailings thickening and detoxification.
The gravity recovery circuit would separate higher density particles from the slurry for regrinding to a finer size prior to being directed to the CIL circuit, whilst the lower density particles from the slurry would be directed to the CIL circuit without any additional grinding.
Carbon-in-Leach Circuit
The proposed CIL circuit would consist of eight agitated leach tanks to which t ........

Recoveries & Grades:
Commodity | Parameter | Avg. LOM |
Gold
|
Recovery Rate, %
| 85 |
Gold
|
Head Grade, g/t
| 1.05 |
Projected Production:
Commodity | Units | Avg. Annual | LOM |
Gold
|
oz
| 192,000 | 1,728,264 |
All production numbers are expressed as metal in doré.
Operational Metrics:
Metrics | |
Stripping / waste ratio
| 4.29 * |
Waste tonnes, LOM
| 91,600,000 bcm * |
Ore tonnes mined, LOM
| 21,300,000 bcm * |
Total tonnes mined, LOM
| 112,900,000 bcm * |
Tonnes milled, LOM
| 60.1 Mt * |
Annual milling capacity
| 7 Mt * |
Annual ore mining rate
| 7 Mt * |
* According to 2017 study.
Reserves at December 31, 2020:
Resources are reported at cut-off grade 0.4 g/t Au.
Reserves are reported at cut-off grade not less than 0.4 g/t Au, that vary according to oxidation and lithology domains.
Category | Tonnage | Commodity | Grade | Contained Metal |
Probable
|
61 Mt
|
Gold
|
1 g/t
|
2,020 koz
|
Indicated
|
69 Mt
|
Gold
|
1 g/t
|
2,280 koz
|
Inferred
|
1 Mt
|
Gold
|
0.6 g/t
|
10 koz
|
Total Resource
|
70 Mt
|
Gold
|
1 g/t
|
2,290 koz
|
Commodity Production Costs:
| Commodity | Units | Average |
Cash costs
|
Gold
|
AUD
|
918.57 / oz *
|
All-in sustaining costs (AISC)
|
Gold
|
AUD
|
990 / oz *
|
Assumed price
|
Gold
|
AUD
|
1,600 / oz *
|
* According to 2017 study / presentation.
Operating Costs:
| Units | 2017 |
OP mining costs ($/t milled)
|
AUD
| 15.5 * |
Processing costs ($/t milled)
|
AUD
| ......  |
Total operating costs ($/t milled)
|
AUD
| ......  |
* According to 2017 study.
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2017 Study Costs and Valuation Metrics :
Metrics | Units | LOM Total |
Pre-Production capital costs
|
$M AUD
|
......
|
OP OpEx
|
$M AUD
|
......
|
Processing OpEx
|
$M AUD
|
613.6
|
G&A costs
|
$M AUD
|
45.3
|
Total OpEx
|
$M AUD
|
......
|
Gross revenue (LOM)
|
$M AUD
|
......
|
Pre-tax NPV @ 5%
|
$M AUD
|
......
|
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- Subscription is required.