THE EXTRACTION OF NICKEL WITH ALIPHATIC OXIMES

U.S. Bureau of Mines researchers investigated the use of aliphatic oximes to extract nickel from acidic, nickelous-chromic-chloride solutions. Batch solvent extraction tests were conducted to characterize the nickel extraction and stripping properties of several oximes. Results indicated that the oximes selectively extracted nickel over chromium by an ion pair mechanism. Nickel was most effectively stripped from the loaded oxime extractants with dilute hydrochloric acid; however, these acidic strip solutions partially degraded the oximes to their parent aldehydes by hydrolysis. The oximes could, however, be regenerated by contacting the solvent phase with a neutralized hydroxylamine-hydrochloride solution. Decyl oxime was successfully used in a continuous counter-current solvent extraction circuit that incorporated loading, stripping, and regeneration stages. The decyl oxime degraded 12 pct per loading and stripping cycle, but was effectively regenerated prior to recycling to the head of the circuit.