Abstract
The Bureau of Mines is investigating a method to recover nickel, cobalt, and copper from laterites containing less than 1.2 pct nickel by reduction roasting, leaching, solvent extraction, and electrowinning unit operations. The method includes three objectives: (1) production from low-grade domestic laterites of critical metals that are domestically in short supply, (2) lower processing energy requirements, and (3) solution recycling. Nickel and copper are coextracted with lix 64n from an ammoniacal-ammonium sulfate batch leach liquor containing 1.00 G/l nickel, 0.30 G/l copper, and 0.02 G/l zinc. Nickel and copper are then separated by selective stripping with spent nickel and copper electrolytes. Cobalt (III) in the nickel- and copper-barren raffinate is reduced to cobalt (II) with cobalt metal. General mills XI-51 extracts cobalt (II) from the treated raffinate. Extracted cobalt is stripped from the XI-51 with spent cobalt electrolyte.
