Treatment of dissolved basic nickel carbonate to obtain nickel

Abstract

A process for recovering nickel from an impure nickel compound which contains a major proportion of nickel values and a minor proportion of other metal values which are relatively soluble in ammoniacal ammonium sulphate solution, and a minor proportion of nickel values and other metal values which are relatively insoluble in the solution. The impure nickel compound is treated with ammoniacal ammonium sulphate solution so that the relatively soluble nickel and other metal values are dissolved in the solution with the relatively soluble nickel values being dissolved substantially as nickel diammine sulphate, and so that the relatively insoluble nickel and other metal values form an undissolved residue. The residue is separated from most of the ammoniacal ammonium sulphate solution so as to provide a substantially residue-free solution of nickel diammine sulphate and relatively soluble other metal values on the one hand and a slurry of the residue of undissolved nickel and other metal values and the solution on the other hand. The substantially residue-free solution is subjected to a reducing operation by hydrogen gas to produce precipitation of elemental nickel powder from the residue-free solution, and the elemental nickel powder is separated from the residue-free solution to produce a first nickel powder product. The slurry is subjected to a reducing operation by hydrogen gas to produce precipitation of elemental nickel powder from the slurry, and the elemental nickel powder is separated from the slurry to produce a second nickel powder product.