Overview
| Stage | Preliminary Economic Assessment |
| Mine Type | Open Pit |
| Commodities |
|
| Mining Method |
|
| Mine Life | 12 years (as of Jan 1, 2022) |
The PEA for Lawyer presents a solid open-pit mining operation with a base case scenario, attractive economics that have the potential to produce additional gold and silver ounces and improved economics through facility design adjustments. |
Source:
p. 28,58
Mineral claims Lawyer are 100% owned by Benchmark Metals Inc., either directly or through its ownership of PPM Phoenix Precious Metals Corp.
Contractors
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Deposit Type
- Porphyry
- Skarn
- Epithermal
- Breccia pipe / Stockwork
- Vein / narrow vein
Summary:
At the centre of the Lawyers Trend are the structurally controlled. Cliff Creek, Dukes Ridge, Phoenix, and AGB zones are located within a large 5 km by 8 km radiometric anomaly that is coincident with potassic alteration and associated with a low-sulphidation epithermal system.
The Cliff Creek, Dukes Ridge-Phoenix and AGB zones are all considered to be structurally controlled, low-sulphidation type epithermal gold-silver deposits. Evidence for a number of different mineral deposit styles occur in the Lawyers Property region, including low- and high-sulphidation epithermal gold-silver mineralisation, calc-alkalic porphyry copper-gold mineralisation, and uncommon iron or copper (± gold and silver) skarn mineralisation.
Volcanic strata on the Property are only very weakly altered and original textures generally well preserved. Narrow localized zones associated with mineralisation in the main zones show intense silicification and potassic alteration. A variety of alteration facies are observed across the Property, ranging from a massive advanced argillic zone north-west of Cliff Creek to the strong quartz-sericite-pyrite alteration concentrated along structures in the Marmot area. The alteration, variation and zonation suggest that the epithermal mineralisation on the Lawyers Property was part of a large-scale hydrothermal system.
The Lawyers Zones consist of a combination of quartz veins, stockwork zones and chalcedony breccia bodies developed al ........
Summary:
For this PEA, conventional, open pit mining was selected as the preferred mining method due to its relative low cost and high productivity, as well as the proximity to surface of the mineralised material. The open pit was selected from a series of optimized pit shells for each deposit. Each of the selected shells were then divided into pushbacks to help optimize the production schedule.
Over the life of mine the deposits are able to produce approximately 47 Mt of resources at a grade of 1.46 g/t AuEq and an overall strip ratio of 6:1. Mining activities will average 70 kt/d with a peak of 110 kt/d over a 12-year life of mine, in order to meet a Mill processing rate of 10,600 t/d (3.9 Mt/a).
The open pit mining activities for the Project are expected to be undertaken by an owner-operated truck/shovel fleet with conventional drill, blast, load and haul operations. Bulk excavation will be performed using hydraulic excavators with back-up units of either hydraulic excavators or a front-end loader. Given the overall scale of operations and equipment requirements, a diesel-powered fleet has been selected.
The open pits will provide mill feed to a crusher at a rate of 10,600 t/d (3.9 Mt/a). It is expected that some mill feed material will be stockpiled close to the crusher and rehandled as required. Waste material will be hauled either to the Tailings Management Facility (TMF) as part of the containment structure, to the Waste Rock Storage Facility ( ........
Source:
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Flow Sheet:
Summary:
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Reserves at June 11, 2022:
Total Mineral Resource Estimate 0.4 g/t Au-Eq Cut-off Pit-Constrained & 1.5 g/t AuEq Cut-off Out-of-Pit.
| Category | Tonnage | Commodity | Grade | Contained Metal |
|
Measured
|
20,304 kt
|
Gold
|
1.21 g/t
|
787 koz
|
|
Measured
|
20,304 kt
|
Silver
|
30.5 g/t
|
19.9 M oz
|
|
Measured
|
20,304 kt
|
Gold Equivalent
|
1.88 g/t
|
1,036 koz
|
|
Indicated
|
47,071 kt
|
Gold
|
1.15 g/t
|
1,734 koz
|
|
Indicated
|
47,071 kt
|
Silver
|
19.6 g/t
|
29.6 M oz
|
|
Indicated
|
47,071 kt
|
Gold Equivalent
|
1.39 g/t
|
2,105 koz
|
|
Measured & Indicated
|
67,376 kt
|
Gold
|
1.16 g/t
|
2,521 koz
|
|
Measured & Indicated
|
67,376 kt
|
Silver
|
22.9 g/t
|
49.6 M oz
|
|
Measured & Indicated
|
67,376 kt
|
Gold Equivalent
|
1.45 g/t
|
3,141 koz
|
|
Inferred
|
4,873 kt
|
Gold
|
2.2 g/t
|
345 koz
|
|
Inferred
|
4,873 kt
|
Silver
|
36.1 g/t
|
5.7 M oz
|
|
Inferred
|
4,873 kt
|
Gold Equivalent
|
2.65 g/t
|
415 koz
|
Water for use in mill processing will be sourced from a combination of reclaim from the TMF (via a floating pump barge), reclaim within the mill circuit from the thickeners, and a freshwater component (sourced from dewatering of the open pits or the historic underground workings).
The reclaim water system from the TMF consists of two vertical turbine pumps (one operating, one standby) positioned on two floating barges, two floating HDPE pipelines that merge into one overland HDPE pipeline, and four centrifugal booster pumps (two operating, two standby). The system is designed with a series of drain points and air release valves for safe operation.
The reclaim system is designed to meet 95% of the total process water requirement, year-round, assuming a 5% freshwater demand. The system uses a single vertical turbine pump mounted on a flotation barge, with 100% installed standby pump capacity. The barge pumps require VFDs to manage the variable head demand due to the fluctuating pond levels during the life of mine. Two booster station pumps, with 100% installed standby capacity, will operate concurrently in series, providing the necessary additional total dynamic head (TDH) to deliver the process water to the Mill.
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