Production Of High Purity Cobalt By Solvent Extraction

摘要

About 50% of cobalt production in the world is done by solvent extraction route. Solvent extraction plays a key role when both Co and Ni are present in the source. India does not have any primary source of cobalt, it meets all its requirements through imports. With growing demand for the cobalt metal in the above scenario, it is worthwhile exploiting the secondary resources. This would not only help in conserving the metal but also help in reducing environmental pollution problems. The important secondary resources from which cobalt values can be recycled are converter slag from copper industry, cobalt sludge, spent catalyst, alnico scrap and 'Beta' cake from Zn industry and cemented carbide tool scrap. In addition to the above, there is another potential future source of Co i.e. polymetallic nodules (PMN) from the ocean bed. Though difficult to mine, PMN form an attractive source due to their vast reserves. India is one of the pioneer country for development and exploiting this source. A pilot plant for treating 500 kg/day of ocean nodules has been set up by the Department of Ocean Development at Hindustan Zinc Ltd., Udaipur. This paper highlights the salient features of the SX processes developed for production of high purity cobalt from the three sources e.g. polymetallic nodules, alnico scrap and spent ammonia cracker catalyst. It has been possible to produce high purity cobalt (>99.9%) with high recoveries from all these secondary sources.