How Did Cobre Achieve Up to 82% Copper Recovery at Ngami?
Cobre Limited reports exceptional copper and silver recoveries from long-term in-situ leaching tests at its Ngami Copper Project, advancing plans for a pilot plant to validate this innovative extraction method.
- Copper recoveries up to 82% from uncrushed drill core samples
- Positive silver extraction enhanced by chloride addition
- Engineering design for ISCR pilot plant completed
- Pilot to validate leachability, hydrogeology, and downstream processing
- Project targets sedimentary-hosted copper-silver mineralisation in Botswana
Exceptional Metallurgical Test Results
Cobre Limited (ASX: CBE) has announced promising results from a four-month in-situ copper recovery (ISCR) leaching test program on its wholly owned Ngami Copper Project (NCP) in Botswana’s Kalahari Copper Belt. The tests, conducted on uncrushed drill core samples, demonstrated copper recoveries as high as 82%, with all samples surpassing minimum thresholds for ISCR viability. Notably, the addition of chloride to the leach solution enhanced silver extraction, underscoring the potential for dual metal recovery.
Pilot Plant Engineering and Next Steps
Building on these metallurgical successes, Cobre has completed the engineering design for an ISCR pilot plant. The design encompasses injection and recovery well layouts, lixiviant mixing circuits, solution ponds, and downstream processing facilities including solvent extraction and electrowinning to produce copper cathode. The pilot aims to assess ore body leachability in situ, refine hydrogeological models through tracer testing, and establish metallurgical process flowsheets, forming a critical component of the environmental impact assessment and permitting process.
Geological Context and Industry Comparisons
The NCP hosts sedimentary-hosted, structurally controlled copper-silver mineralisation dominated by fine-grained chalcocite amenable to acid leaching. This mineralisation occurs below the water table within well-fractured zones, ideal for ISCR methods. Cobre is targeting a scale and process analogous to North American ISCR projects such as Taseko Mines’ Florence Copper and Copper Fox’s Van Dyke deposits, both significant copper resources employing similar in-situ recovery techniques.
Implications for Project Economics and Development
CEO Adam Wooldridge highlighted the potential economic benefits of ISCR at Ngami, noting that copper recoveries in the 50% range could yield exceptional project economics due to the relatively low capital and operating expenditures associated with ISCR compared to conventional mining. The pilot plant will provide vital data to validate these projections and support the upcoming Mineral Resource Estimate (MRE), advancing the project towards production.
Looking Ahead
Following pilot plant commissioning, Cobre plans to conduct solvent extraction and electrowinning test work on the pregnant leach solution to confirm downstream processing viability. Further leaching trials will also assess variability and optimize reagent consumption. These steps are essential to de-risk the project and demonstrate the scalability of the ISCR approach in Botswana’s copper belt.
Bottom Line?
Cobre’s ISCR advances at Ngami could redefine copper extraction economics in Botswana, but pilot results will be pivotal.
Questions in the middle?
- How will pilot plant performance translate to full-scale operational recoveries and costs?
- What are the environmental and permitting challenges unique to ISCR in the Kalahari Copper Belt?
- How might silver recovery impact overall project economics alongside copper?
