South32 reports 61% ore reserve estimate increase for Sierra Gorda

South32 Ltd on Tuesday reported an increase in the ore reserve and mineral resource estimates for Chile’s Sierra Gorda copper mine.

The Perth, Australia-based diversified miner has a 45% stake in the mine, which it acquired back in 2022. The remaining 55% stake is held by Poland-based partner KGHM Polska Miedz.

New estimates for the open-pit mine point to “enhanced orebody definition”, South32 said, based on drilling spanning 85,000 metres and 200 drillholes between 2023 and 2025.

The ore reserve estimate is now 1.10 billion tonnes, up 61% from previous estimates, averaging 0.39% copper, under 0.1% molybdenum and 0.06 grammes per tonne of gold, at a total copper equivalent grade of about 0.5%.

The mineral resource estimate now stands at 1.87 billion tonnes, averaging 0.37% copper, less than 0.1% molybdenum and 0.06 grammes per tonne of gold, at a 0.4% copper equivalent grade.

The initial resource life of Sierra Gorda has been extended by five years to 2045.

South32 Chief Executive Matt Daley commented: “This update highlights the scale, quality and long-life orebody at Sierra Gorda, which we expect will be a significant source of copper for decades to come. It follows the approval in July to proceed with execution of the fourth grinding line project at Sierra Gorda, which is expected to increase copper production by approximately 30% from 2031.

“With the current orebody remaining open at depth, the mine offers potential for further growth beyond today’s increase to ore reserve and reserve life.

The CEO added: “We continue to work with our joint venture partner to drive further growth and value at Sierra Gorda. This includes the Catabela Northeast exploration project, where exploration holes have intersected significant copper mineralisation, highlighting the potential for future mine life extension.”

South32 shares rose 1.0% to 266.60 pence each on Tuesday morning in London, and were up 1.2% at ZAR58.04 in Johannesburg. The stock closed 1.2% higher at AUD5.13 on Tuesday in Sydney.

The company is due to report full-year results on Thursday.

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