Abstract: The present invention relates to a solvent extraction process for selectively recovering copper from an aqueous solution containing copper and nickel and having a pH above about 9. By employing only limited amounts of oxime, sufficient to provide about equivalent exchangeable hydrogen ion therein to latent copper ion of the aqueous stream, copper ion can be extracted in a multistage countercurrent process preferentially to nickel or cobalt. Hydrogen ion of the oxime molecule exchanges with copper ion in the aqueous solution in accordance with the equation:(2R.sup.o H)org. + (CU.sup.++)aqu. .fwdarw.(R.sub.2.sup.o Cu)org. + (2H).sup.+ aqu.wherein R.sup.o is the organic moiety of the oxime. The oxime selectively extracts copper when the mole ratio of exchangeable hydrogen ion of the oxime to copper ion in the aqueous is maintained between about 1.8 and 2.4.

Abstract: A process for selectively removing ammonia from an organic solution containing ammonia and an oxime-metal chelate which comprises countercurrently contacting the organic solution with an aqueous solution of ammonium carbonate, ammonium bicarbonate, alkali metal bicarbonate or mixtures thereof. The mole ratio of ammonia, in organic solution prior to contact with the carbonate solution, to carbonate and/or bicarbonate in the fresh aqueous scrub solution is maintained so that ammonia transfer is effected from the organic solution to the aqueous solution. In the fresh scrub solution, the carbonate or bicarbonate concentration is maintained sufficiently high to prevent substantial emulsification of aqueous phase in the organic solution and the ammonia concentration is less than the ammonia concentration in equilibrium with 50 mg/l ammonia in the organic solution.

Abstract: A process for scrubbing extracted ammonia from oximes. The process is particularly adaptable as a secondary scrub, prior to acid stripping, in a process in which metals are recovered from ammoniacal leach liquors by solvent extraction. The present process eliminates the pH rise of the aqueous scrub liquor associated with acid scrubbing of ammonia from oximes into which ammonia has been extracted. Extractable metal sulfates are utilized in an aqueous scrub solution at a pH <7. The net result is an exchange of ammonia on the oxime for copper or nickel in the scrub solution with resulting loading of copper or nickel by the oxime and the formation of ammonium sulfate in the aqueous scrub solution with no change in the pH of the aqueous scrub solution.

Abstract: Ammoniacal leach solutions containing nickel and copper (and possibly other base metal values) are treated by first extracting copper leaving nickel in the raffinate. The nickel in the raffinate is subsequently extracted with an organic extractant. The nickel loaded organic extractant is subsequently stripped with a highly concentrated ammonium salt solution to yield a strip concentrate from which nickel or nickel oxide is recoverable without electrolytic treatment. To prevent build up of copper in the nickel extraction circuit, part or all of the organic from the nickel strip circuit is recycled back to the copper extraction circuit where copper on the organic is eventually stripped. In the copper extraction circuit, the nickel on the recycled organic is replaced by copper from the aqueous, preventing build up of nickel on the organic leaving the copper extraction circuit.

Abstract: Method for treating basic salts to preferentially extract copper without using a base to maintain the required pH. The liberation of unreacted hydrogen ions during the ion exchange reaction is eliminated by partially dissolving the basic salt mixture with an amount of acid that is equivalent to the non-copper content of the basic mixture. An amount of organic ion exchange extractant is selected so that the exchangeable hydrogen ion on the extractant is equivalent to or in excess of the amount of copper in the metal bearing liquor.