South32 has significantly increased the ore reserve estimate at its Sierra Gorda copper mine in Chile, with the updated figure rising by 61% to 1.1 billion tonnes. The increase strengthens the long-term outlook for the major copper operation and extends its initial reserve life by approximately five years to 2045.
The updated estimate, effective as of July 31, 2026, contains an average grade of 0.39% total copper, 0.016% molybdenum and 0.06 grams per tonne of gold, equivalent to a total copper-equivalent grade of about 0.46%. South32 holds a 45% interest in Sierra Gorda, while KGHM Polska Miedź owns the remaining 55%.
Extensive Drilling Supports Reserve Increase
South32 said the higher reserve estimate follows improved understanding and definition of the Sierra Gorda orebody after an extensive infill drilling campaign. Around 85,000 metres of drilling across approximately 200 holes were completed between 2023 and 2025.
The company’s updated mineral resource estimate also increased by 8% to 1.87 billion tonnes, grading 0.37% total copper, 0.016% molybdenum and 0.06 grams per tonne of gold, with a copper-equivalent grade of 0.44%.
Fourth Grinding Line to Boost Copper Production
The reserve upgrade comes shortly after South32 approved the development of a fourth grinding line at Sierra Gorda. The expansion is expected to increase copper production by approximately 30% from 2031, further strengthening the mine’s contribution to South32’s copper portfolio.
The company said the orebody remains open at depth, leaving potential for additional resource growth. Exploration at the Catabela Northeast target has also identified significant copper mineralisation, which could support further extensions to the mine’s operating life.
Strategic Importance for Copper Supply
The reserve expansion is significant as global demand for copper continues to rise, driven by electrification, renewable energy infrastructure, power networks, electric vehicles and other energy-transition technologies.
With a larger reserve base, longer mine life and planned processing expansion, Sierra Gorda is positioned to remain an important source of copper from Chile for decades. South32 management has described the operation as a long-life asset with further growth potential.
The company is expected to continue drilling and exploration activities while progressing the fourth grinding line project. Further discoveries at depth or around the existing operation could provide additional opportunities to extend production beyond the currently projected 2045 reserve life.