ASX listed Blackham Resources is looking to access a treasure trove of largely free gold locked away in decades of old tailings that have accumulated at the Wiluna Gold Project since the 1930s.
The company has already estimated a free milling mineral resource of 33.6 million tonnes grading 0.57 grams per tonne gold, for 620,000 ounces of contained gold, from drilling at the tailings.
About 77% of this resource is in the Indicated category.
Metallurgical test work done to date has shown that recoveries of between 42% and 50% are possible in a standard gold leaching process similar to the existing Wiluna CIL circuit.
Work has also confirmed that there is no need for further grinding of the tailings material, making reprocessing a simple, cost effective option.
Additional metallurgical test work will be carried out to potentially enhance the gold recoveries while ongoing technical work is expected to confirm potential mining and processing options that may be integrated into Blackham’s future operations.
The resource was taken from Dam C and Dam H along with the Adelaide, Golden Age, Moonlight and Squib pits. It does not include Dam J, where tailings from current operations are being deposited.
Most of the tailings contain residue from sulphide ores with some oxide and transitional ore residues from the mining of the Wiluna open pits between 1985 and 1997.
Blackham is also continuing exploration into the priority Lake Way targets and results are pending from the initial phase of drilling, the first new drilling in that area for 12 years.
The company produced 19,393oz of gold in the June 2018 quarter, taking its total production for the half year to 30 June 2018 up to 40,024oz at all in sustaining costs of $1294 an ounce.
Blackham also provided a 2019 financial year production guidance of between 77,000oz and 89,000oz at an AISC of $1250 to $1450 per ounce.
Last month, its drilling confirmed that mineralisation at the Golden Age underground mine extends beyond the current mining areas.
Best results of up to 6.9m at 15.5 g/t gold were returned 150-300m below current mining levels whilst surface drilling at the Golden Age North project area intersected high grade, shallower mineralisation amenable to open pit mining with a peak intercept of 2 metres at 28.3 grams per tonne gold.
Continuity of the mineralised structure at Golden Age North has now being confirmed over a 600m strike and to a depth of more than 150m with mineralisation remaining open.
By Matt Birney
