Purification of sulphuric acid solutions from the leaching of nickelliferous of laterites

Abstract

Low-grade nickelliferous laterites are important sources of nickel and cobalt, since 80% of the world’s known reserves of nickel are associated with such types of deposits. Nickel can be produced by pyrometallurgical and hydrometallurgical routes. However, for the lower-grade lateritic ores, hydrometallurgical treatment seems to be favourable for the simultaneous recovery of nickel and cobalt, as far as plant economics and environmental aspects are concerned [1,2]. Sulphuric acid heap leaching, at ambient temperature, of a low-grade limonitic laterite Greek ore has been reported [3,4]. Despite the efficient extraction of nickel and cobalt, contamination of the pregnant leach solution with impurities is unavoidable. A typical chemical composition of leach liquors is given (table I). This shows that a significant amount of dissolved Fe, as well as other impurities such as Al, Cr, Mg, Na and K, are present in solution along with Ni and Co. Thus, before the electro-extraction of these metals, a prior solution purification step is required.