SEPARATION OF COBALT AND NICKEL

摘要

1499406 Separation of cobalt and nickel values INCO EUROPE Ltd 7 April 1976 [24 April 1975] 17025/75 Heading C1A Cobalt values (and copper values if also present) are separated from nickel values in an aqueous acid sulphate, chloride or nitrate leach solution by contacting the solution with a solution, in an inert substantially water-immiscible organic liquid, of the nickel salt of an organo-phosphoric acid of formula (RO) 2 PO(OH), wherein each R, which may be the same or different, is hydrogen or substituted or unsubstituted alkyl, aryl or alkaryl, provided that not more than one R is hydrogen, each R group contains at least 8 carbon atoms and the phosphoric acid molecule contains at least 12 carbon atoms, so as to transfer cobalt values from the aqueous leach solution to the organic solution; separating the organic leach solution containing transferred cobalt values from the aqueous raffinate solution; and crystallizing some or all of the raffinate solution to produce crystals of nickel sulphate, chloride or nitrate. The preferred organophosphoric acid is di-(2-ethylhexyl)phosphoric acid. Preferred organic solvents are kerosine and naphtha. It is preferred to scrub the cobalt-loaded organic extract with sulphuric, hydrochloric or nitric acids or an aqueous solution of cobalt sulphate, chloride or nitrate in order to increase the Co/Ni ratio therein prior to stripping the cobalt values. The cobalt values may be stripped from the organic solvent by means of sulphuric, hydrochloric or nitric acids to produce an aqueous solution of the corresponding cobalt salt and a solution of the organo-phosphoric acid itself. The organo-phosphoric acid may then be re-converted to its nickel salt (optionally after conversion to its alkali metal or ammonium salt first) by treatment with an aqueous nickel sulphate, chloride or nitrate solution (together with an aqueous alkaline solution in the case of direct re-conversion). The organic solution of the organo-phosphate nickel salt is then re-cycled to the cobalt extraction step. The aqueous solution of nickel sulphate, chloride or nitrate used in re-conversion may be the mother liquor obtained on crystallizing the aqueous raffinate obtained from the initial cobalt extraction step. The process may be performed without an emulsion inhibitor in the organic phase.