Abstract: Copper can be extracted from an ammoniacal copper solution by contacting said solution with an organic phase containing a first extraction reagent consisting of a beta-diketone as well as a second extraction reagent consisting of a hydroxy oxime, a hydroxy quinoline, or an alkylaryl sulphonamido quinoline. Alternatively, the copper solution can first be contacted with an organic phase containing the first extraction agent, and subsequently be contacted with an organic phase containing the second extraction reagent. It is possible to reach a low percentage of copper in the aqueous solution by using a low number of extraction steps.

Abstract: A process is described for regenerating a spent ammoniacal etching solution containing copper values. The process comprises extracting copper from the spent etching solution by means of an organic solution containing a reagent which is capable of selectively extracting copper ions from the spent etching solution. The process also comprises extracting copper from the washing water originating from the etching process.

Abstract: A liquid-liquid extraction process is disclosed, in which an aqueous solution, containing metal ions, is contacted with an organic liquid substantially insoluble in water. The organic liquid contains two water-insoluble reagents, viz. a diester of dithiophosphoric acid and an organic phosphate, in a preferred volume ratio of between 1:10 and 2:1. The organic liquid may also contain a diluent for the reagents.

Abstract: Zinc is recovered from a material containing zinc and iron. The material is leached with sulphuric acid to produce a final pH of 3-5.5. Zinc powder is added to the leaching solution to precipitate polluting metals. Zinc is now extracted with a solution of a dialkyl phosphoric acid in an organic solvent. Zinc is extracted from the organic solution with sulphuric acid. Zinc is recovered from the sulphuric acid solution as metal or as zinc sulphate.

Abstract: A mixture of metal hydroxides is leached with an ammoniacal carbonate solution, to dissolve nickel, copper and zinc. Metal is recovered from the leaching solution. The solid leaching residue is leached with sulphuric acid at a pH of 1.5- 3, to dissolve a further amount of nickel, copper and zinc. The acidic leaching solution is passed to the ammoniacal leaching process.