Abstract: A method for precipitating nickel and cobalt from an acid aqueous solution containing at least dissolved nickel, cobalt and manganese, comprising adding solid caustic calcined magnesium oxide or freshly slurried caustic calcined magnesium oxide to the solution in an amount sufficient to precipitate a substantial proportion of the nickel and cobalt in solution and to precipitate a minor proportion of the manganese in solution; maintaining the magnesium oxide in contact with the solution for a period of about 1 hour to about 9 hours to thereby achieve precipitation of a substantial proportion of the nickel and cobalt in solution and precipitation of a minor proportion of the manganese in solution; and separating solids precipitated in the prior step from the aqueous solution.

Abstract: A method for precipitating nickel and cobalt from an acid aqueous solution containing at least dissolved nickel, cobalt and manganese, the method including: adding solid caustic calcined magnesium oxide or freshly slurried caustic calcined magnesium oxide to the solution, the magnesium oxide being added in an amount sufficient to precipitate a substantial proportion of the nickel and cobalt in solution and to precipitate a minor proportion of the manganese in solution, maintaining the magnesium oxide in contact with the solution for a period of about 1 hour to about 9 hours to thereby achieve precipitation of a substantial proportion of the nickel and cobalt in solution and precipitation of a minor proportion of the manganese in solution; and separating solids precipitated in step (b) above from the aqueous solution. Preferably, about 80% to 100% of the Ni and Co in solution is precipitated and about 5% to 15% of the Mn in solution is precipitated. The precipitated material separates early from the solution.