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Electrolytic Reduction of Cobalt in Ammoniacal Leach Solutions.
Hundley-GL; Siemens-RE; Phillips-TA
MISSING :20 pages
The Bureau of Mines has devised and demonstrated an ammoniacal sulfate leach process for recovering nickel and cobalt from low- grade domestic laterites. Solvent extraction of cobalt, one of the process steps, requires the reduction of hexammine complexes of co3+ to co2+ in an ammoniacal leach solution. Previously, reduction was accomplished using cobalt metal shot in a column. This report presents experimental results and an economic evaluation comparing two alternate techniques with the shot column: (1) an electrolytic reduction cell with an extended surface area cathode and (2) direct electrowinning from purified leach solution using a cell with a fluid bed cathode. The second alternative eliminates the conventional solvent extraction-electrowinning steps. The costs of the three methods, based on the requirements of a proposed commercial-sized plant, including all unit operations, were determined by the Bureau's process evaluation group. The operating costs for the shot column,$1.19/Kg CO, and for electrolytic reduction, $1.20/Kg, are essentially the same, but the cost of direct electrowinning, $3.77/Kg CO, would eliminate this method as a practical alternative. The capital cost of approximately $14.4 million for reduction in a shot column is much higher than the approximately $4.4 million for electroreduction.
IH; Report of Investigations
Page last reviewed: March 11, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division