OZ Minerals is set to invest $47 million towards the expansion of its Prominent Hill copper-gold mine in South Australia.
The company intends to spend the majority of the investment on further infill drilling to convert the Prominent Hill inferred resources to reserves ahead of making a final investment decision next year.
The latest study is only based on a third of Prominent Hill’s inferred resource of 59 million tonnes outside the current life of mine plan. However, it is forecast to lower site operating costs by $10-$15 per tonne and reduce greenhouse gas emissions intensity.
OZ Minerals plans shift to an electrified shaft and underground fleet at Prominent Hill.
“The positive findings of the Prominent Hill expansion study on a relatively small case increases our confidence in Prominent Hill’s longevity and ongoing performance,” OZ Minerals managing director Andrew Cole said.
“While examining only a portion of the mineral resource, the study showed significant cash flow uplift, improved safety and lower mining costs and emissions intensity.”
The study also confirms the feasibility of replacing truck haulage with a 1360 metre vertical hoisting shaft installation at the mine from 2025.
This would attract around $450 million in cost, which will be spent over four years starting next year.
Underground mining rates at Prominent Hill is now averaging around four million tonnes a year and anticipated to hit 4 to 5 million tonnes a year from 2022.
The increased mining rates would reduce the current mine life from 2031 to 2030 while maintaining the plant at full capacity to the end of 2024, 18 months longer than originally planned.
At the Carrapateena gold-copper mine in South Australia, mineral resources exceeded five million tonnes of contained copper.
Cole said it was pleasing to see an increase to metal in the Carrapateena mineral resource as the company continued to improve its knowledge of the orebody during the early stages of production.
“This provides further confidence in the potential for a multi decade mining province through an expansion beyond the current sub-level cave,” he said.
Meanwhile, mining of the Antas open pit in Brazil will cease early next year, with the Carajas Antas hub continuing to process ore from the Pedra Branca mine.