Abstract: Nickel and cobalt contained in aqueous sulfate solution are separately recovered by counter-current solvent extraction using a cobalt-selective organic extractant while scaling of equipment and cobalt recycle are minimized by controlling aqueous pH at the extraction, scrubbing and stripping stages to maximize cobalt loading and selectivity of the extractant while loading scale-causing ions such as calcium and magnesium in the extractant and removing them from the circuit with the aqueous cobalt strip solution.

Abstract: Aqueous nickel chloride solutions containing such impurities as copper, iron, and zinc, and optionally, cobalt, and having an acid concentration ranging from about 0.2 N to 4 N HCl together with a total chloride concentration of about 4 N to 11 N are purified of said impurities by solvent extraction with an organic extractant of essentially tributyl phosphate (TBP) dissolved in a water-immiscible organic solvent, the solvent extraction being carried out at a selected concentration of TBP and a selected volume ratio of organic to the aqueous solution effective to produce a nickel raffinate substantially impoverished in said impurities.

Abstract: An organic liquid extractant of at least one oxime, selected from the group consisting of ketoximes and .alpha.-hydroxyoximes dissolved in an organic solvent, useful in separating nickel from cobalt in process solutions or in recovering both nickel and cobalt from process solutions, is treated with a salt of hydroxylamine at intervals to maintain the activity of the oxime in the extractant. The organic extractant can also contain sulfonic acids to facilitate treatment of more acid process solutions and is treated with a hydroxylamine salt to regenerate oxime degraded by the highly acid process solutions, the extractant itself and the concentrated acidic stripping solutions.