Process for hydrometallurgical upgrading

Abstract

This invention relates to a process for hydrometallurgical treatment of concentrates of sulphides of copper, nickel, cobalt, lead and iron and copper-containing mattes. A first embodiment of the process includes subjecting a finely ground slurry of a sulphide concentrate to an oxidation leach at elevated temperature and pressure in the presence of an oxygen-bearing gas to preferentially leach cobalt and nickel and to convert galena to lead sulphate. The reaction mixture is heated to a further elevated temperature, in the absence of oxygen, to convert a portion of chalcopyrite to insoluble simple copper sulphides and ferrous sulphate solution and to decompose complex insoluble ferric compounds. The resulting mixture is subjected to differential flotation whereby a lead concentrate and a copper concentrate are obtained. The solution is reduced in acid content by addition of limestone, the iron is precipitated and removed, and nickel and cobalt are precipitated in the remaining solution as sulphides and recovered as a concentrate. The second embodiment of the process includes subjecting a copper-containing matte to an oxidation leach at elevated temperature and under pressure of an oxygen-bearing gas whereby a copper sulphate-containing solution is formed for use in the process of the first embodiment and solids residue is recovered as a concentrate.