The invention is a process for winning nickel by treating an aqueous ammonium salt solution of nickel salts with a carbon monoxide-containing gas under reducing conditions to produce nickel carbonyl and subsequently recovering nickel therefrom. Optionally, the production of nickel carbonyl can be catalyzed, for example, by cyanide. Also, an essentially water-immiscible solvent for nickel carbonyl can optionally be employed. The aqueous ammoniacal solution is typically an aqueous ammoniacal ammonium chloride, carbonate, sulfate, hydroxide, or mixture thereof. The valuable metals associated with nickel, e.g., copper, cobalt, iron, and precious metals, are also separated and recovered by this process. The general nature of the process allows a wide variety of primary and secondary sources of nickel to be utilized by combining this process with a number of known ore-treatment steps.