South32 Lifts Sierra Gorda Ore Reserves 61 Percent Extending Mine Life to 2045
South32 has boosted the Sierra Gorda copper mine’s Ore Reserves by 61%, extending its reserve life by five years to 2045, underpinned by extensive infill drilling and a planned processing expansion.
- 61% increase in Ore Reserves to 1.1 billion tonnes
- Reserve life extended to 2045 with fourth grinding line approved
- Mineral Resources up 8% to 1.87 billion tonnes
- Infill drilling of 85,000 metres from 200 holes completed
- Copper production set to rise 30% from 2031
Ore Reserves Surge and Mine Life Extension
South32 (ASX:S32) has revealed a substantial 61% increase in the Ore Reserve estimate for its Sierra Gorda copper mine in Chile, lifting it to 1.1 billion tonnes as of 31 July 2026. This jump extends the mine’s reserve life by approximately five years to 2045, a significant extension for an operation that began production in 2015. The boost reflects the impact of a rigorous infill drilling campaign comprising around 85,000 metres from 200 drillholes completed between 2023 and 2025, which enhanced the definition of the orebody.
Mineral Resources Also Climb Amid Ongoing Exploration
The updated Mineral Resource estimate rose by 8% to 1.87 billion tonnes, averaging 0.37% total copper, alongside molybdenum and gold credits. This increase underscores the robustness of the underlying geology and the potential for further resource growth. South32’s CEO Matt Daley highlighted that the orebody remains open at depth, indicating untapped potential beyond the current reserve expansion. Exploration at the Catabela Northeast project has already intersected significant copper mineralisation, suggesting avenues for future mine life extensions.
Processing Expansion to Boost Production
Following the approval in July 2026 of the fourth grinding line project, Sierra Gorda’s processing capacity is set to rise from 135,000 tonnes per day to 165,000 tonnes per day by 2031. This expansion is expected to lift copper production by approximately 30%, a meaningful increase that aligns with the extended reserve life. The project leverages existing infrastructure, including renewable power contracts and a seawater pipeline, supporting sustainable operations in the Antofagasta region.
Robust Technical and Economic Foundations
The Ore Reserve and Mineral Resource estimates comply with the JORC Code (2012) and incorporate detailed geological, metallurgical, economic, and operational factors. Mining assumptions include a 6.5% average dilution and 96.2% recovery, while metallurgical recoveries average 83% for copper, 54% for molybdenum, and 47% for gold. The net smelter return (NSR) cut-off grade ensures only economically viable material is included. Independent audits conducted in 2026 affirmed the soundness of the estimation methodologies and the underlying data quality.
Strategic Partnership and Infrastructure
South32 holds a 45% interest in Sierra Gorda, jointly controlled with majority partner KGHM Polska Miedź. The operation benefits from high-quality processing equipment and well-established logistics, including rail and road connections to export ports. The mine’s integration of renewable energy and seawater supply contracts reflects a commitment to sustainable resource development. Environmental approvals are secured through 2035, with plans underway to extend these in line with the longer mine life.
Bottom Line?
South32’s Sierra Gorda reserve upgrade and processing expansion set the stage for sustained copper output growth, but future exploration and environmental approvals will be critical to fully realise this potential.
Questions in the middle?
- How will commodity price assumptions evolve given the undisclosed copper equivalent pricing?
- What progress will be made on environmental approvals to extend mine life beyond 2035?
- Can exploration success at Catabela Northeast translate into further reserve extensions?
