South32 Ltd. said on Friday its Sierra Gorda copper mine in Chile’s Antofagasta region has seen a 61% increase in ore reserves, bringing the total to 1.1 billion tonnes as of July 31, 2026.
The upgrade follows infill drilling of roughly 85,000 meters across 200 drillholes conducted between 2023 and 2025, which refined orebody definition. The updated reserves carry an average grade of 0.39% copper, 0.016% molybdenum and 0.06 grams per tonne of gold, with a copper-equivalent grade of 0.46%. The reserve life has been extended by about five years to 2045.
The company also reported a mineral resource estimate of 1.87 billion tonnes at similar grades. South32 acquired a 45% interest in Sierra Gorda in February 2022, with joint venture partner KGHM Polska Miedź holding the remaining 55%.
South32 has approved a fourth grinding line at the mine, which will lift processing capacity from 135,000 tonnes per day to 165,000 tonnes per day. The expansion is expected to boost copper output by roughly 30% starting in 2031. Over the 2026-2045 period, payable production is forecast at 3.548 million tonnes of copper, 982,000 ounces of gold and 93,000 tonnes of molybdenum.
The estimates comply with the 2012 Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves.
