Nickel recovery employing carbonyl ferrates

摘要

A novel process for recovering nickel metal from aqueous ammoniacal nickel solutions such as leach liquors at or close to ambient temperatures and pressures. The process comprises contacting the nickel solution with carbonyl ferrate ions such as HFe(CO)4- or Fe(CO)4-- in the presence of carbon monoxide to produce nickel carbonyl. The nickel carbonyl is collected as a gas, concentrated, and decomposed to produce nickel metal and carbon monoxide. The carbonyl ferrate ions may conveniently be produced by subjecting an iron pentacarbonyl solution to an aqueous alkaline solution containing potassium hydroxide or the like. The nickel depleted ammoniacal liquor is purged of iron resulting from the nickel carbonylation treatment by oxidizing the ferrous values to iron oxide and may thereafter be recycled to solubilize additional nickel values. The iron oxide in turn may be reduced to iron pentacarbonyl and treated with an aqueous alkaline solution for reuse in carbonylation of additional nickel values.