Many industries make extensive use of hydrogenation nickel catalyst for conversion of fats into oil which creates large amount of spent catalysts containing environmentally hazardous and economically valuable metals. In the present study, a simple recovery process for nickel and oil from spent hydrogenation catalyst using hydrochloric acid leaching was described. Simultaneous recovery of nickel and oil varies with acid concentration, time, temperature and solid-liquid ratio. Under the optimum

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... ndition of leaching Viz. 4 N hydrochloric acid, 90 0 C temperature, 1.10 gm/ml solid liquid ratio and 2 hrs reaction time, it was possible to recover 98.5% nickel along with 99.8% oil. Purification of this recovered leaching liquor was performed by adjusting pH of leach liquor containing nickel, iron, aluminium and calcium to 5.5 with sodium carbonate followed by addition of hydrogen peroxide for removal of iron and aluminium. Then ammonium oxalate was added, followed by dilute ammonia solution to neutralize the acid which precipitates calcium oxalate. To this resulting solution, required quantity of sodium carbonate was added to recover nickel as nickel carbonate which was found to be 99% pure.