OZ Minerals is buoyed by its growth prospects at the Prominent Hill mine in South Australia and West Musgrave project in Western Australia, with both recording resource boosts to June 30, 2021.
It comes as the Tier 1 miner released updated exploration figures that indicated changes in the company’s mineral resources and ore reserves over the past year.
Prominent Hill’s underground ore reserve increased by approximately 26 per cent to 48 million tonnes (Mt), with copper up about 27 per cent and gold up about 31 per cent.
The mine’s underground copper mineral resource increased by seven per cent in the 2020/21 financial year.
“Increases in mineral resources (at Prominent Hill) … were primarily due to the inclusion of information from additional delineation and grade control drilling completed, offset by depletion of existing surface stockpiles and ongoing mining of the underground mineral resource,” OZ Minerals stated.
Prominent Hill’s ore reserve stockpiles decreased by approximately 20 per cent to 12Mt to June 30, 2021, with copper down about 17 per cent and gold down about 38 per cent. This came as OZ Minerals completed stockpile processing at the site.
West Musgrave has also enjoyed a boost, with an updated ore reserve of 253Mt at 0.35 per cent copper and 0.32 per cent nickel.
“The ore reserve tonnes have increased by approximately 15 per cent and were due to the net result of updated operating costs based on increased throughput opportunity, metallurgical test work, and changes in metal price and exchange rate assumptions,” OZ Minerals stated.
The company completed 47.5 kilometres of infill drilling at West Musgrave during 2021, with the aim to increase orebody confidence.
“It is pleasing to see the contribution of our growth projects with significant increases of the mineral resource and ore reserve at both Prominent Hill and West Musgrave adding approximately five per cent to group ore reserve copper metal tonnes over the last 12 months,” OZ Minerals managing director and chief executive officer Andrew Cole said.
Cole said developments at Prominent Hill were particularly significant.
“The 2020/21 drilling program at Prominent Hill, focussed on infill drilling to convert material from inferred to indicated resources. It resulted in an increased confidence in our orebody knowledge and informed the approval of the Wira shaft mine expansion,” he said.
“The expansion will see a long and productive future for Prominent Hill with the Wira shaft enabling access to areas previously thought uneconomic and opening up potential new prospects.”
OZ Minerals stated that about 67Mt of mineral resource remained outside the Wira shaft expansion mine plan, which the company hopes to convert to ore reserves in coming years.