Method of winning copper, nickel, and other metals

A process for recovering nickel values form manganese sea nodules, said process comprising:

• a. comminuting said nodules;
• b. subjecting the comminuted nodules to a reducing roast to convert the nickel values to nickel metal;
• c. cooling the reduced nodules under non-oxidizing conditions;
• d. oxidatively leaching said reduced nodules with an aqueous ammoniacal ammonium carbonate solution having a molar ratio of ammonia to metal of from 0:1 to 100:1 by injecting an oxygen-containing gas into a slurry of said reduced nodules in said aqueous ammoniacal ammonium carbonate solution;
• e. contacting the resultant leach solution containing nickel ammonium salt complexes with a carbon monoxide-containing gas at a temperature of from about 50.degree. to about 250.degree.C and a pressure of from about 50 to about 3000 psig whereby the nickel values are reduced to nickel carbonyl;
• f. separating said nickel carbonyl from said leach solution;
• and
• g. decomposing said nickel carbonyl to metallic nickel.