PROCESS FOR REMOVING AMMONIA FROM SOLUTIONS OF OXIME-METAL CHELATE

摘要

1453859 Removal of ammonia from solutions of oxide-metal chelates KENNECOTT COPPER CORP 20 Nov 1973 [20 Dec 1972] 53745/73 Heading C1A Ammonia is removed selectively from an organic solution containing ammonia, nickel and/ or copper and a chelating oxime to obtain a solution having less than 50 mg. ammonia per litre by contacting the solution counter-currently with an aqueous solution of ammonium carbonate, ammonium bicarbonate, alkali metal bicarbonate or a mixture of two or more thereof having an ammonia concentration less than that which would be in equilibrium with 50 mg. per litre ammonia in the organic solution, effecting ammonia transfer to the aqueous solution without substantial emulsification of the latter in the organic solution, and separating the effluent organic solution from the aqueous solution. The process is preferably operated with a mole ratio of ammonia in the incoming organic solution to carbonate and/or bicarbonate in the aqueous solution, prior to contact between the two solutions, such that 1-4 scrubbing stages reduce the ammonia in the effluent organic solution to less than 50 mg. per litre. The effluent organic solution may then be contacted with an aqueous sulphuric acid solution, or an ammonium sulphate/sulphuric acid solution, having a pH sufficient to prevent metal being stripped from the organic solution, or with water, to remove substantially all (e.g. to less than 5 mg./litre) of the ammonia. A number of aliphatic saturated and unsaturated hydroxy ketoximes and of alkyl substituted ortho-hydroxy benzophenoximes are listed as suitable oximes; the organic medium is for example kerosine. The process of the invention forms part of a method for recovering nickel and/or copper from aqueous ammoniacal solutions, such a solution being extracted with an organic oxime solution to obtain the chelate solution here used as starting material; the effluent organic solution from which the ammonia has been removed by the present process is stripped with aqueous acid e.g. H 2 SO 4 to recover one or both metals and the latter are obtained by for example electro-winning from the aqueous acid.