Cobre (ASX:CBE) is planning to truck 30,000 tonnes a month of ENAMI copper oxide material to its Sierra Atacama Copper Project in Chile to lift plant utilisation.
The company agreed to buy 150,000 tonnes of crushed, leached copper oxide material from a stockpile held by Chilean state miner Empresa Nacional de Minería (ENAMI).
ENAMI’s material grades 0.65% copper, within a range of 0.50–1.10%, with a purchase price of US$4 ($5.70) per tonne. Delivery adds US$5 a tonne, with the stockpile sitting within 55km by road of Sierra Atacama.
Cobre intends to blend the feed with ore from its underground operations to keep its leach and solvent extraction-electrowinning circuit utilised as underground production ramps up and open-pit plans advance.
Column leach testwork on the material returned 58% copper recovery, with laboratory acid consumption of 45kg a tonne. The company applies a recovery assumption of 50% for industrial-scale planning.
CEO Adam Wooldridge says Sierra Atacama provides the company with a ‘unique’ opportunity to establish a regional copper processing hub in an established mining district with “limited electrowinning capacity”.
“Securing approximately 150,000 tonnes of low-cost ENAMI material, while simultaneously recovering copper from historical ponds and re-leaching historical pads, gives us three potential sources of incremental copper that can utilise infrastructure already in place,” Wooldridge says.
Cobre has started two workstreams to generate more pregnant leach solution (PLS) from material already on site.
The first involves re-leaching historical stacked leach pads. Previous operators stacked the pads 30m high and achieved recoveries of 50–55%. Cobre reportedly achieves 72–82% through finer crushing, lower stack heights, and dynamic leaching.
The second workstream targets copper-rich sediments in four remaining historical lixiviant ponds. The company circulates water through the material to dissolve copper sulphates, then filters the solution into the existing PLS circuit.
Cobre targets first copper from the program by the end of the quarter.
Cobre is focused on copper production in Chile and tier-one copper exploration in Botswana.
Write to Paula Fabe at Mining.com.au
Main image: Cobre
