GB798478A - Improvements in or relating to the hydrometallurgical production of cobalt and nickel - Google Patents

Abstract

Nickel and cobalt sulphides are precipitated from liquors containing these metals together with either or both of iron and aluminium, by adjusting the liquor to a free acid content of not more than 30 grams/litre and not less than that equivalent to pH 3.5, clarifying the liquor and then treating it at 60 DEG to 150 DEG C. with hydrogen sulphide under pressure. If temperatures in the range of 60 DEG to 90 DEG C. are employed the pH must be in the range of 1-3 and preferably 2-2.5 and a catalyst consisting of powdered iron, nickel, cobalt or mixtures of nickel and cobalt metal must be present. The initial liquors may be obtained by the sulphuric acid leaching of ores, generally non-sulphide ores. Finely-divided solids such as the oxides or sulphides of nickel, or infusorial earth, talc or graphite may be added in amounts from 0.1 to 5 grams/litre of solution treated in order to prevent wall deposits. According to examples: (1) liquor obtained by sulphuric acid leaching of lateritic ore, containing 14 to 15 grams/litre of free sulphuric acid was first neutralized to pH 2.5, for example with limestone, and then heated to about 100 DEG C. in an autoclave and subjected to an overpressure of 50 p.s.i.g. whilst being agitated. The bulk of the precipitate formed a soft plating on the wall. If 0.1 grams of finelydivided infusorial earth is added the sulphides of nickel and cobalt settle rapidly. (6) A similar liquor was neutralized to pH 1.5 with soda ash, heated to 65 DEG C. and hydrogen sulphide bubbled through under a partial pressure of 25 p.s.i.g. and in the presence of fine iron particles. The latter were obtained by reduction with hydrogen of the residual tailing solids from the sulphuric acid leaching of lateritic ores. Nickel and cobalt sulphides were precipitated, contaminated with iron, which could be avoided by replacing the iron catalyst by cobalt or nickel.