Cobaltickel separation from acidic leach liquors

摘要

This paper describes the recovery and separation of cobalt and nickel from acidic leach liquors derived from the heap leaching of laterite ores. Flowsheets based on the use of organophosphorus acids and synergistic mixtures of organophosphorus acids and #alpha#-hydroxyoximes are discussed and critically assessed. The flowsheet finally chosen for detailed study involves the bulk extraction of cobalt and nickel at pH 7-8 using the magnesium salt of Versatic acid to eliminate pH control. Good recoveries of cobalt and nickel are achieved in a two-stage counter-current extraction, however with some co-extraction of manganese. This can be scrubbed along with residual magnesium and calcium in the organic phase by contact with a small amount of strip liquor. Stripping of cobalt and nickel from the organic phase is possible with 1.0 mol/dm~3 sulphuric acid to give a strip liquor concentration of 52 g/dm~3 nickel, 4.2 g/dm~3 cobalt from a loaded organic phase containing 1 g/dm~3 nickel and 0.8 g/dm~3 cobalt.