Removing ammonia from solutions of oxime-metal chelate

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. The ammonia-depleted organic solution can be contacted with water or an aqueous solution of sulfuric acid or an aqueous solution of a sulfuric acid-ammonium sulfate mixture to remove additional ammonia prior to recovering metal therefrom.