Production of high purity cobalt oxalate from spent ammonia cracker catalyst

A process was developed to produce > 99.9% pure cobalt oxalate from spent ammonia cracker catalyst pellets containing ∼ 20% Co generated at heavy water plants. A pilot plant for producing kilograms of cobalt oxalate of required purity has been set up. The process consists of leaching, oxidation, solvent extraction, ion exchange and oxalate precipitation. The major impurities present in the leach liquor after nitric acid oxidation were Fe3+, Al3+ and Ni2+. Fe3+ and Al3+ were separated from the leach liquor by using a solvent extraction (SX) process employing a mixed extractant system consisting of D2EHPA and TBP. Ni2+ was separated by ion exchange (IX) employing Dowex M4195 resin.