The CESL Copper Process
The CESL Copper Process consists of four main steps:
- copper mineral oxidation,
- copper leaching from the oxidation residue,
- solvent extraction to purify the copper leach liquor, and
- electrowinning to recover copper in a commercial product form.
The CESL Copper Process involves oxidation of sulphide concentrates at elevated pressure and temperature in the presence of catalytic chloride ions. In addition to copper, impurity metals such as nickel, cobalt, and zinc are oxidized during the pressure oxidation process. Depending on the concentrate metallurgy, it may be economically feasible to recover some of the more valuable impurity metals from the process solution.
The leach filter cake, containing oxidized copper, hematite and elemental sulphur is repulped with recycled raffinate from Solvent Extraction. The pH of the slurry is controlled in order to efficiently leach the copper from the pressure oxidation filter cake.
Impurities are removed from the copper-rich solution by solvent extraction, a conventional process used throughout the world. The purified solution is then electrowon, producing copper cathodes of LME Grade A standards.
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