Abstract: An improved process for separating cobalt values from nickel values in an aqueous nickel and cobalt sulphate-containing solution in which the solution is contacted with a water-immiscible organic solution containing an organophosphorous acid in a cobalt extraction circuit. The process is particularly useful for aqueous solutions containing high total metals content and elevated cobalt concentrations, while avoiding the formation and precipitation of ammonium sulphate containing double salts during the solvent extraction of the cobalt. The improvement includes contacting a portion or all of the water-immiscible organic solution required for cobalt extraction with a nickel-containing ammoniacal solution to produce a nickel-loaded organic phase and a partially nickel-depleted raffinate.

Abstract: A process is disclosed for separating and recovering nickel and copper values from a nickel-copper matte which may contain iron and arsenic. Finely divided nickel-copper matte is leached in aqueous sulphuric acid solution under oxidizing conditions at atmospheric pressure and at a minimum temperature of about 80.degree. C. to selectively leach nickel from the matte to produce a nickel sulphate solution having a final pH in the range of about 4.0 to 6.5, preferably about 6.5, and to produce a copper-rich sulphide residue. The copper-rich sulphide residue is separated from the nickel sulphate solution and leached in a closed reaction vessel at a minimum temperature of about 120.degree. C. under a non-oxidizing atmosphere in a sulphuric acid solution containing an effective amount of copper and sulphuric acid to provide a terminal concentration of at least about 2 g/L Cu.sup.

Abstract: This invention is directed to an improved process for leach treating gold and silver bearing pyritic and arsenopyritic concentrates and ores. More particularly, the improved process avoids the necessity of adding recycled neutralized solution to the leach solution, thereby alleviating difficulties in maintaining acid levels in the leach solution, and provides for bleeding solutions containing dissolved arsenic, iron and sulphate from the process without the loss oxidized nitrogen species. The process can be carried out in one or more tubular reactors. The process for recovering valuable metals from pyritic and arsenopyritic concentrates and ores involves decomposing the arsenopyrite or pyrite concentrates and ores in acidic solution in a common volume space which contains a gas phase and a liquid slurry (which comprises a liquid phase and a solid phase) through the action of higher valence oxidized nitrogen species in which the nitrogen has a valence of at least plus 3.

Abstract: A process for the hydrometallurgical recovery of precious metal from an ore or concentrate containing at least some arsenopyrite or pyrite.

Abstract: A novel hydrometallurgical process for the recovery of copper, and optionally iron, from sulfide copper concentrates containing common copper sulfides such as chalcopyrite, bornite and chalcocite using electrowinning cells wherein the anolyte and the catholyte are separated by a solution-impermeable cation exchange membrane.