Abstract: A process for the production of a sulphidic copper concentrate from a complex sulphidic concentrate containing as its main constituents copper, iron and at least one non-ferrous metal selected from the group consisting of zinc, lead, nickel and cobalt, comprising mixing the complex sulphidic concentrate with a copper-containing predominantly chloridic solution thereby to form a suspension, and treating the suspension thus obtained at elevated temperature and pressure at a pH-value of below 3, thereby to form a sulphidic copper concentrate, thereby the non-ferrous metals being extracted from the concentrate without formation of significant amount of acid. Precious metals may also be present. Advantageously the ratio by weight of the complex concentrate added to the copper-containing predominantly chloridic solution to the copper content of the solution is such that the predominantly chloridic solution after being at least partly freed from copper by an exchange reaction has a potential at 60.degree. C.

Abstract: Process for selectively separating precious metal such as silver and gold from a chloride solution of the precious metals and other heavy metals which involves:(a) adding finely divided activated carbon to the solution for reduction of gold to gold metal and absorption of the gold metal by the carbon,(b) adding an aqueous solution of an iodine compound for selective precipitation of further precious metal including the silver, if present.During steps (a) and (b) the pH is below 3 so that hydrolysis with the metal ions does not occur, and the potential of the solution during step (b) is such that no substantial decomposition of the iodine compound occurs. The precipitated precious metal and active carbon are separated, dried, and admixed with an iodine binder, and the resulting admixture is subjected to reduction for formation of a regulus containing the precious metal.

Abstract: Copper sulfate solution obtained by the sulfuric acid leaching of cupriferous material and containing impurities such as Fe, As, Sb, Bi, Se, Te, Sn, Pb, Cl, Ag, Hg, and PO.sub.4, are subjected to a two step purification process. In the first step, the pH is adjusted to 2.7-3.3 with, e.g. Ca(OH).sub.2, and the potential in relation to the standard hydrogen electrode is adjusted to at least 575 mv with an oxidizing agent, e.g. air. The temperature is 50.degree.-90.degree. C. Impurities precipitate and are separated. Se, Cl, and possibly Ag and Hg remain in solution and are removed in the second step, wherein the potential is reduced to below 350 mv by addition of a cupriferous reducing agent, e.g. Cu or Cu.sub.2 O. The pH is below 3 and the temperature is below 50.degree. C. Impurities precipitate as copper (I) compounds, and are separated to provide the solution in condition for the electrolysis. The copper produced is of high purity, having a conductivity of at least 58.8 mho .times. m/mm.sup.

Abstract: A process for working up of a concentrate containing Cu, Zn, and precious metal including at least one of Ag or Au. In a first stage, the concentrate or the concentrate in modified form is leached for hydrometallurgically dissolving out the copper and zinc and leaving a residue containing the precious metal, and the leach liquor is separated from the residue. In a second stage, residue is subjected to a chlorinating sulfatizing roasting, and the roasted residue is leached with a selective solvent for the precious metal, e.g. aqueous NaCl, for dissolving the precious metal out of the residue.