Processing of nickel- and cobalt-containing leach liquors obtained from different raw materials

Abstract

Acidic as well as ammoniacal leach liquors obtained from three different raw materials, namely, lateritic nickel ores, copper converter slag and Indian Ocean manganese nodules, were treated for removal of impurities and separation of copper, nickel and cobalt. Precipitation and solvent extraction techniques were used for these purposes. Iron and silica impurities from acidic solutions were removed by lime precipitation. In ammoniacal medium, iron was coprecipitated with manganese. Manganese was removed as manganese dioxide by oxidative precipitation from both media; this removal also results in some loss of cobalt due to its adsorption on the manganese dioxide matrix. From sulphate solutions, copper was extracted using LIX 64N ® ∗ ∗ LIX is a registered trade mark of Henkel Corporation. followed by nickel-cobalt coextraction using di-2-ethylhexylphosphoric acid (D2EHPA). From the loaded solvent, nickel and cobalt were separated by the crowding technique. From ammoniacal solution, both copper and nickel were coextracted with LIX 64N and separated by selective stripping from the loaded organic phase. Cobalt was recovered either by sulphide precipitation or by adsorption on lignite followed by desorption with sulphuric acid/spent electrolyte.