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Solvent Extraction of Cobalt from Laterite-ammoniacal Leach Liquors.
Nilsen-DN; Siemens-RE; Rhoads-SC
MISSING :23 pages
The Bureau of Mines is developing a method to recover ni, CO, and cu from laterites containing less than 1.2 pct ni and 0.25 pct carbon monoxide The method consists of the following basic unit operations: (1) reduction roasting, (2) leaching, (3) solvent extraction, and (4) electrowinning. This report deals with the extraction of cobalt and the preparation of a suitable cobalt electrolyte by solvent extraction from liquor produced by this method. Nickel and copper are coextracted with lix64n from an ammoniacal ammonium sulfate leach liquor containing about 1.00 G/l ni, 0.30 G/l CO, 0.03 G/l cu, and 0.02 G/l zn. Cobalt(III) in the nickel-copper barren raffinate is reduced to cobalt (II) with cobalt metal. Reduction of cobalt (III) to cobalt (II) greatly aids subsequent extraction. Commercially availalbe XI-51 extracts about 94 pct of the cobalt from the treated raffinate in one stage in a laboratory mixer- settler continuous circuit. Ammonia loaded on the solvent is removed in two washing steps. About 94 pct of the cobalt then is stripped from the XI-51 in one stage with spent cobalt electrolyte containing about 77 g/l CO and 18 g/l sulfuric acid (h2so4). Electrolytes containing less h2so4 also may be used. Preliminary data indicate that coextracted zinc may be removed from pregnant cobalt electrolyte containing 3 g/l or less h2so4 with di-(2- ethylhexyl) phosphoric acid (d2ehpa).
IH; Report of Investigation;
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division