US Patent 7357827 Integrated ammoniacal solvent extraction and hydrogen reduction of nickel

A process is provided for the recovery of a metallic nickel product in a solvent extraction process which includes the steps of forming a nickel ammine complex by stripping nickel from a nickel loaded organic phase with a high strength ammonia solution and then reducing the nickel ammine complex with hydrogen from the high strength ammonia solution to produce a metallic nickel product. By virtue of the present process, a reductive precipitation of nickel by hydrogen is obtained so as to recover a metallic nickel product, and the process is advantageous in that it will allow for commercial processes wherein nickel may be recovered by hydrogen reduction based on high strength ammonia solutions.