Abstract: A process is disclosed for separating cobalt in the form of cobalt (III) hexammine sulphate from an aqueous solution containing cobalt (III) hexammine sulphate and nickel (II) hexammine sulphate comprising adding ammonium sulphate to provide an effective amount of ammonium sulphate, saturating the solution with an effective amount of ammonia at a temperature whereby the triple salt of cobalt (III) hexammine sulphate, nickel (III) hexammine sulphate and ammonium sulphate is precipitated, recovering the precipitated triple salt from the solution, and repulping the triple salt with an effective amount of water or aqueous ammonia solution to selectively leach nickel (II) hexammine sulphate to produce a crystalline cobalt (III) hexammine sulphate with a cobalt: nickel ratio of at least 100:1.

Abstract: A process for removing mercury or other metal impurities from elemental sulphur contaminated therewith includes mixing such elemental sulphur in a molten state with an aqueous sulphide solution or an aqueous solution of sufficiently high pH which reacts with elemental sulphur and forms a sulphide solution to cause extraction of mercury or other metal contaminants from the elemental sulphur into the aqueous sulphide solutions, and separating the aqueous sulphide solution containing mercury or other metal contaminants from the molten elemental sulphur to provide an elemental sulphur product substantially free from mercury and other metal contaminants.

Abstract: A process is disclosed for recovering zinc, lead, copper and precious metals from zinc plant residue, said process comprising leaching the residue with return zinc spent electrolyte, neutralizing residual acid and reducing ferric iron in the solution by addition of zinc sulphide concentrate in the presence of a limited quantity of oxygen, flotation of the resulting slurry to separate unreacted zinc sulphide, treatment of flotation tailings with sulphur dioxide and elemental sulphur to further leach iron, zinc and impurity elements and precipitate copper, flotation of the resulting slurry to separate a copper sulphide concentrate, thickening, filtering and washing of the flotation tailings followed by addition of lime and sodium sulphide to activate lead sulphate and flotation of a lead concentrate from the residue.

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: A process for the production of powdered metallic cobalt by reduction of cobaltous ammonium sulphate solutions. A soluble silver salt, preferably silver sulphate, is added in an amount to provide a soluble silver to cobalt weight ratio in the range of 1 to 10 g silver:1 kg cobalt, an organic dispersant such as bone glue or polyacrylic acid, or mixture thereof, is added in an amount of 0.01. to 2.5% of the weight of the cobalt, an ammonia to cobalt mole ratio of about 1.5:1 to 3.0:1 is established, and the solution is heated to a temperature in the range of 150 to 250.degree. C., preferably about 175.degree. C., with agitation under a hydrogen pressure of 2500 to 5000 kPa for a time sufficient to reduce the cobaltous sulphate to cobalt metal powder.