Mining Depletion Trims Motheo Reserves: What’s Next for Sandfire?
Sandfire Resources reports a consolidated update on its Motheo copper-silver asset in Botswana, revealing declines in mineral resources and ore reserves due to mining depletion and remodelling. The company plans to declare a maiden ore reserve for the A1 deposit by mid-2026, aiming to extend mine life.
- Motheo Mineral Resources at 59.5Mt with 1.0% Cu and 13.6g/t Ag
- Ore Reserves at 42.4Mt with 0.9% Cu and 13.5g/t Ag, reflecting mining depletion
- 8% decrease in resource tonnes and 7% decrease in ore reserve tonnes since June 2024
- Advanced geological modelling improves understanding of mineralisation controls
- Maiden Ore Reserve for A1 deposit targeted for June 2026
Consolidated Resource and Reserve Update
Sandfire Resources Ltd (ASX – SFR) has released its latest consolidated Mineral Resource and Ore Reserve estimates for the Motheo asset in central western Botswana as of 31 December 2024. The update encompasses the T3, A4, and A1 deposits, incorporating mining depletion from ongoing operations at T3 and A4.
The total Mineral Resource stands at 59.5 million tonnes grading 1.0% copper and 13.6 grams per tonne silver, containing approximately 570,000 tonnes of copper and 26.2 million ounces of silver. This represents an 8% reduction in contained tonnes and an 11% decline in contained copper compared to the mid-2024 estimate, primarily due to mining depletion and refined geological modelling.
Ore Reserves have similarly decreased to 42.4 million tonnes at 0.9% copper and 13.5 grams per tonne silver, equating to 381,000 tonnes of copper and 18.4 million ounces of silver. This reflects a 7% drop in ore tonnes and an 11% reduction in contained copper since June 2024, with mining depletion at T3 accounting for most of the decline.
Geological Insights and Modelling Advances
Recent infill and extension drilling campaigns have significantly enhanced Sandfire’s understanding of the lithological and structural controls on mineralisation at Motheo. The company has developed revised ore domain models for the T3 and A4 deposits, which underpin the updated resource and reserve estimates. These models honour the complex folded stratigraphy and thrust-related structures characteristic of the Kalahari Copper Belt.
The T3 deposit, mined since March 2022, features structurally controlled copper-silver-molybdenum mineralisation within folded sedimentary sequences. The A4 deposit, with mining commencing in late 2023, shares similar geological characteristics but exhibits a more uniform lithological context. Both deposits have been modelled using advanced geostatistical methods, including Ordinary Kriging and dynamic anisotropy, to accurately estimate grades and volumes.
Operational and Economic Context
Mining at Motheo is conducted via conventional open-pit methods, supported by grade control drilling and detailed geotechnical studies. The Motheo processing plant, commissioned in 2023, employs standard crushing, grinding, and flotation techniques to produce a silver-bearing copper concentrate with an average life-of-mine grade of approximately 30% copper.
Economic assumptions for the Ore Reserve estimation include a copper price of US$3.70 per pound and silver at US$21 per ounce, with metallurgical recoveries averaging above 92% for copper and 84% for silver. Transport and treatment costs, royalties, and penalties for deleterious elements have been incorporated into the financial models, reflecting current contracts and market conditions.
Looking Ahead – A1 Deposit and Mine Life Extension
While the maiden Mineral Resource estimate for the A1 deposit remains unchanged since April 2024, Sandfire is advancing exploration and technical studies with the goal of declaring a maiden Ore Reserve for A1 in the June quarter of 2026. This milestone is a critical step in Sandfire’s multi-year exploration program designed to secure a minimum 15-year mine life at Motheo.
Sandfire’s CEO Brendan Harris highlighted the operational success of Motheo Copper Operations and the emerging status of the Kalahari Copper Belt as a significant copper-producing region. The company’s extensive landholding and geological insights position it well to expand resources and reserves through ongoing exploration and development.
Environmental and Social Considerations
Environmental and social impact assessments for T3 and A4 have been approved by Botswana’s Department of Environmental Affairs, with comprehensive baseline studies completed. Waste rock management, water resources, and mine closure plans are in place to ensure sustainable operations. The project benefits from robust infrastructure, including proximity to major highways, power supply, and a dedicated accommodation camp for workers, with over 95% of the workforce sourced locally.
Bottom Line?
Sandfire’s Motheo update reflects operational realities and geological refinement, setting the stage for A1’s maiden reserve and a longer mine life.
Questions in the middle?
- How will the maiden Ore Reserve for A1 impact Motheo’s overall production profile and valuation?
- What are the risks to resource and reserve estimates from commodity price volatility and metallurgical performance?
- How might ongoing exploration and drilling success alter the 15-year mine life target?