Reoximation of metal extraction circuit organics

摘要

A process for purifying a degraded oxime metal extractant organic phase from a metal extraction circuit wherein a degraded oxime metal extractant organic phase comprised of an oxime metal extractant, and aldehyde or ketone degradates in a water immiscible hydrocarbon solvent is reoximated thereby restoring the oxime extractant organic phase for further extraction in the metal extraction circuit. Optionally the degraded organic phase may be purified by distillation prior to reoximation. The distillation is carried out in a wiped film evaporator at temperatures above 180 DEG C. up to about 250 DEG C. at a pressure from about 0.5 mm Hg or lower up to about 10 mm Hg and the reoximation is carried out with hydroxylamine in the presence of a weak organic carboxylic acid as a phase transfer catalyst and in the presence of an alkali metal or alkaline earth metal hydroxide or carbonate, preferably sodium carbonate.