Главная – Журналы – Химия в интересах устойчивого развития 2004 номер 1

The separation of cobalt from nickel in aqueous solution has always been a problem for hydrometallurgists. Their adjacent positions in the transition metal series in the periodic table result in aqueous chemical behaviour that is too similar for development of easy separation routes. Traditionally cobalt and nickel were separated by processes based on selective oxidation and/or precipitation of cobalt from either sulphate or chloride solution and such processes are still in use today. However, the process of solvent extraction provides the high degree of separation and yields demanded by industry nowadays. While alkylamines are the extractants of choice for separation of cobalt from nickel from chloride liquors, for weakly acidic sulphate liquors the alkyl phosphorous acids have found significant commercial application at various locations around the world. Because of the high nickel to cobalt ratio encountered in liquors produced in sulphate-based high nickel matte leach processes or those produced in the acid pressure leaching of nickel laterites, very high separation factors (>1000) are required. That is why the dialkyl phosphinic acid CYANEX 272 has become the reagent of choice for such duties. This paper reviews the chemistry of cobalt-nickel separation from aqueous solutions and comments on the implications of this chemistry in hydrometallurgical applications. Description of selected applications is given and discussed.