Perth-based Wiluna Mining has wrapped up a mammoth 175 kilometres of drilling over the past 18 months to support a major resource and reserve upgrade integral to its stage 2 sulphide development feasibility study, due for completion in the March quarter of 2022.
The company says its drilling strategy over the past 18 months has been successful in defining thick high-grade intervals at shallow levels close to previously mined zones with available access for rapid low-cost development.
Latest drilling results from East Lode and Happy Jack lodes continue to impress with intercepts grading up to 53.4 grams per tonne gold confirming Wiluna as a large scale, high-grade mineralised system.
Happy Jack and East Lode are earmarked as the initial mining areas in the company’s stage one development plan to increase gold production at Wiluna to about 120,000 ounces per annum next year. Redevelopment of the underground operation was recently reported to be on track with production building to 750,000 tonnes per annum.
The company said drilling was designed to increase the level of confidence in the mineral resource and in high priority mining areas in the one to five year mining plan window, along with confirmation of the company’s reserves.
Drilling at Happy Jack has coughed up a slew of high-grade intercepts including 1.72 metres at 26.84 grams per tonne containing an impressive 0.83m at 53.4 g/t gold and 6.65m at 7.59 g/t gold.
Interestingly, the company said the latest round of drilling has the potential to grow the resource where holes have intersected the mineralised shear zone below the current resource limits.
Results from drilling at East Lode also continue to deliver wide, high-grade intercepts such as 19m at 7.03 g/t gold. A further notable intercept was 11.3m at 3.95 g/t including 2m at 7.79 g/t and 2m at 6.3 g/t gold, in a single hole.
Management said the final phase of drilling at East Lode was focussed on infilling the main hosting structure, along with infilling known hanging wall and footwall lodes. The additional stacked lodes show promise for significant resource growth according to the company.
Over 1 million ounces have been produced from the mining of East Lode, which was developed mainly in the 1930’s and 1940’s and briefly in the early 2000’s. The latest round of drilling results demonstrate high-grade mineralisation remains in-situ surrounding historically mined stopes.
Wiluna said the latest batch of results come from an additional 56 diamond holes for more than 13,200m of resource development drilling.
Drilling continues underground with three rigs focussed on mine development and grade control at the multi-million-ounce gold camp where Wiluna currently boasts resources in the order of 153.50 million tonnes grading at 1.63 g/t gold for 8.04 million ounces gold, including a high-grade resource of 26.9 million tonnes at 4.89 g/t gold using a 2.5 g/t cut-off.
The stage 2 feasibility study, which aims to take production up to 250,000 ounces of gold per annum, is currently underway and is expected to be completed to a bankable level by March 2022. Offtake agreements for 100% of the gold concentrate for the first three years of production have already been secured with Trafigura and London-listed Polymetal Group.
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By Matt Birney
