Patent ID: 7749302

Claim:
A method for a recovery of valuable metals from a sulphidic concentrate containing copper, zinc, and one or more valuable metals selected from the group consisting of nickel, lead and cobalt, comprising: (a) a first leaching, comprising leaching the sulphidic concentrate in a sulphate milieu under oxidising conditions, such that the sulfuric acid concentration is in the range of 40-50 g/l the oxidation-reduction potential of the solution is 350 to 450 mV with reference to an Ag/AgCl electrode, to produce: (i) a leaching solution of said zinc and said one or more valuable metals selected from the group consisting of nickel, lead and cobalt, and (ii) a leached concentrate containing most of the copper of the concentrate in an undissolved state; and (b) a second leaching, comprising: (i) leaching the leached concentrate counter-currently with a concentrated alkali chloride-copper (II) chloride solution, thereby generating a copper (I) chloride solution; (ii) cleaning impurities from the copper (I) chloride solution that is generated; (iii) precipitating copper (I) oxide from the copper (I) chloride solution by contacting the copper (I) chloride solution with an alkali hydroxide, thereby forming an alkali chloride solution and precipitated copper (I) oxide; (iv) routing the alkali chloride solution to a chlorine-alkali electrolysis to produce chlorine, alkali hydroxide and hydrogen, which are used in the first leaching, and in copper recovery, and (v) reducing the copper (I) oxide to metallic copper.