This Desktop study was conducted to develop an understanding of the metallurgical requirements for the Treatment of an existing tailings stockpile in the DRC.
The establishment of operations for the Stockpile Project is based upon a simple dry recovery of the tailings from the stockpile using front end loaders (FEL).
The study assumes that acid leaching will provide the required dissolutions recovery based on historical sample assay results.
This study considered various flowsheet options which evaluated conventional direct acid leaching to generate a copper and cobalt pregnant solution (PLS) that can be sold to the neighboring process plants as the base case. Alternative options also considered a final copper cathode and cobalt precipitate salt to increase the possible LME value. A high level financial tradeoff resulted in selecting a small plant throughput, with the least capital cost, but still producing a final copper and cobalt product for maximum metal revenues.
Different flowsheets were compared. This included the provisional development of operating and capital costs for each flowsheet as part of an options study, before a choice was made to take the preferred flowsheet forward.
The chosen flowsheet is simplistically described as:
- The recovery of material from the stockpile.
- Curing and leaching of the recovered stockpile material with reagents.
- Solid/liquid separation.
- Separation of copper and cobalt in a solvent extraction plant.
- Electrowinning of copper to produce a copper cathode.
- Cobalt will be precipitated out separately as a saleable cobalt salt.