Meeka Metals says recent metallurgical results from its Meekatharra project in Western Australia’s Mid West region, including 95.5 per cent gold leach recovery, will allow the inclusion of its Turnberry underground resource into a looming DFS.
The testwork explored conventional carbon-in-leach (CIL) recoveries at three grind sizes and gravity recovery at two grind sizes, reporting optimal recoveries at 106 microns for both methods. Optimal leach grind sizes were investigated by ALS Metallurgy at 150, 106 and 75 micron (1 micron = 0.001mm), while gravity recovery performance was examined at the two coarser grinds.
The company says key outcomes include optimal gravity gold recovery of 48 per cent at grind sizes of both 150 and 106 microns, while 24-hour leach results yield 93.7 per cent recovery at a 150 micron grind and an improved recovery of 95.5 per cent at the 106 micron grind setting.
Importantly, the testwork also found that leach kinetics were rapid, with the majority of the gold being extracted into solution inside eight hours, accompanied by low cyanide and lime consumptions. Meeka says the outcomes show that strong gold recoveries are achievable from the proposed Turnberry underground feed material using conventional gravity recovery and CIL processing, as designed in the company’s recommissioned and expanded Murchison processing plant.
Composited metallurgical samples were drawn from three locations, all of which were below the base of oxidation (that is, in fresh rock).
One composite sample was taken from about 30m below the design floor of the oxide open-pit design used in the company’s May DFS. A second sample was drawn from a further 60m below the first.
The third composite was pulled from about 75m below the second sample, near the bottom of Meeka’s planned underground extension block, which the company has lined up for a significant campaign of about 7500m of reverse-circulation (RC) drilling, slated to kick off in just eight days. The drilling will initially target depths between about 200m and 235m below surface to explore the extension potential of and below the two high-grade plunging main shoots at Turnberry, which remain open at depth.
The nearest previous drill pierce-points to the proposed drilling include intercepts of 4m at 8.8 grams per tonne gold and 44m at 1.1g/t, sitting close to the second composite sample site.
The composite samples were selected in three subsets each to accommodate all three grind sizes and to encompass four rock types – felsic volcanics, felsic tuff, sediments and dolerite.
Meeka Metals managing director Tim Davidson said: “Having expanded processing capacity, increasing throughput by 30 per cent, we are now confirming new, high-margin underground production sources to fill that capacity. High gold recoveries, rapid leach kinetics and low reagent consumption support the inclusion of underground mining at Turnberry in the updated DFS due in December 2024.”
Management says that after the extension drilling is completed, it plans to kick off a program of about 15,000m of grade-control drilling for all of its stage-one oxide open pits. The plan is to combine two objectives – to pick up the pace of mine production to meet the expanded mill’s increased hunger for feed material and to improve productivity by eliminating in-pit grade control-related activities during mining.
The company is targeting two underground mines – Turnberry and Andy Well – to come into production in the medium term to provide ore in the grade range of about 4g/t to 5g/t gold to its expanded 650,000 tonnes per annum processing plant.
The upshot is expected to be a material uptick in production exceeding that presented by the company in its DFS, while any expansion in the underground resource from the upcoming extension drilling is expected to further bolster the operation.
Meeka’s flagship Murchison gold project has a combined 281-square-kilometre landholding, with a 1.2 million-ounce resource at 3g/t gold that sits within granted mining leases.
The company’s DFS is focusing on restarting its fully-permitted Andy Well mill and outlines a straightforward development strategy with strong financial outcomes, including post-tax net cash flows of $413 million, a post-tax NPV of $244 million and a post-tax IRR of 100 per cent during an initial nine-year production plan.
Is your ASX-listed company doing something interesting? Contact: matt.birney@businessnews.com.au
By Doug Bright
