- 01Phase 1 vat leach promising; Phase 2 underway.
- 02Vat leach reduces water capex vs heap leach.
- 03DFS: NPV $1.5b; IRR 17.6%; 35-yr open pit.
Alliance Nickel (ASX: AXN) has reported promising Phase 1 vat leach results carried out as part of a capital cost optimisation program for its NiWest nickel-cobalt project in Western Australia.
The company dispatched a 2-tonne sample of NiWest ore to an overseas facility to assess parameters including ore sizing, agglomeration conditions, leach kinetics, and resulting nickel-cobalt recoveries
Encouraging extraction outcomes have subsequently prompted the company to approve the move to the next phase of testing.
Phase 2 is designed to better represent expected commercial vat operating conditions including acid usage and importantly, will assess ore variability across a greater extent of the main Mt Kilkenny orebody.
Life-of-Mine Ore Profile
Aided by a second suite of composite samples representative of the life-of-mine ore profile, the work will support the continued evaluation of vat leaching as an alternative flowsheet to the on/off heap leach configuration outlined in the project’s 2024 definitive feasibility study (DFS), potentially reducing water infrastructure costs and possibly improving leaching performance.
The DFS confirmed NiWest as a commercially attractive development opportunity based on a 35-year open pit operation producing battery-grade nickel-cobalt sulphate.
It estimated a post-tax net present value of $1.5 billion, a 17.6% post-tax internal rate of return, and first-quartile all-in sustaining costs from an ore reserve of 84.7 million tonnes at 0.94% nickel and 0.06% cobalt.
Alliance has targeted completion of Phase 2 testing by year end, with the results expected to inform an update to the feasibility work.
Reduced Water Demand
A key driver of the NiWest testing program is the significant reduction in water demand that vat leaching is expected to deliver compared to heap leaching, which would require a $310 million investment to build 200 kilometres of water pipeline infrastructure—a substantial portion of the DFS capital costs.
Preliminary analysis indicates that under a vat leach flowsheet, sufficient water could be sourced locally from the Mt Kilkenny tenement, thereby offering the potential for material reductions in water-related capital expenditure.
Alliance plans to construct additional production bores at Mt Kilkenny to help confirm the local water supply that would underpin the vat leach option.
Vat leaching also has potential to deliver metallurgical benefits including improved solution distribution, enhanced leach kinetics, and shorter leach cycle times, while remaining an atmospheric leach process consistent with the design basis of the existing DFS flowsheet.
Alliance managing director Paul Kopejtka said the results to date reinforced the view that vat leaching had the potential to simplify the NiWest flowsheet and reduce capital intensity.
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