Covellinisation of copper sulphide minerals under pressure leaching conditions

A series of laboratory experiments have been performed on pressure leaching in oxygenated sulphuric acid solutions of commercial copper flotation concentrate produced by Lubin Concentrator (KGHM, Poland). Major copper sulphides: chalcopyrite, bornite and chalcocite were reported to undergo phase conversion to covellite (CuS), which was found to be the most stable sulphidic form of copper. The formation of copper sulphide (covellite) appeared to be a significant step in the examined pressure leaching process. Copper present in the flotation concentrate was observed to be solubilised in the leaching solution only after the conversion of all copper sulphide minerals into the covellite phase. Permeable, openwork texture of covellite formed during the copper sulphide conversion facilitates easy leaching and transport of the leaching medium to the leaching surface, effecting leaching of the remaining minerals in the solid feed.