Abstract: A process is provided for the production of a nickel metal powder by reduction of an ammoniacal nickel (II) carbonate solution essentially free of metallic nickel. A soluble silver salt is added in an amount to provide a soluble silver to nickel weight ratio of 1.0 to 10.0 grams per kilogram of nickel, an organic dispersant, such as gelatin, is added in the amount of 5.0 to 20.0 grams per kilogram of nickel Ni (II), together with a spheroid-promoting agent such as anthraquinone in an amount of about 1.0 to 5.0 grams per kilogram of nickel. The solution is heated to a temperature in the range of 150.degree. to 180.degree. C., with agitation, under a hydrogen pressure of about 3.5 MPa for a time sufficient to reduce the ammoniacal ammonium nickel (II) carbonate solution to micron-sized nickel metal powder. A high purity, micron-sized nickel metal powder of generally spheroid particulate configuration is produced. The nickel metal powder has an average particle size of about 0.5 microns.

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.

Abstract: A process for removing dissolved selenium IV values from an acidic aqueous copper sulphate solution includes passing the solution through a tubular member in a plug flow manner and injecting sulphur dioxide or a sulphite solution into the solution as it enters the tubular member. When the sulphate solution also contains dissolved selenium (VI) values, the ratio of dissolved selenium (IV) values to dissolved selenium (VI) values is preferably at least 3 to 1.