Solvent extraction of nickel (II) sulphate contaminants
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Institute of Non-Ferrous Metals
Leszek Gotfryd   

Institute of Non-Ferrous Metals; Sowinskiego 5; 44-101 Gliwice; Poland
Publication date: 2005-01-01
Physicochem. Probl. Miner. Process. 2005;39(1):117–128
Potentials of the solvent extraction method for separation of contaminants, especially Co(II), from nickel(II) sulphate solutions have been reviewed. Properties of most important and commercially available organic preparations, making extractive separation of these elements possible, have been shortly characterized. On the basis of laboratory investigations, behaviour of cationic liquid ion exchangers, Cyanex 272 and Cyanex 302, used for Co(II) and Ni(II) separation, has been compared. Co-extraction isotherms of most important contaminants, including Zn(II), Cu(II) and Co(II), with Cyanex 272, from solutions of nickel(II) sulphate have been examined. Next, the extractant has been applied to purification of the so called crude nickel(II) sulphate or CNS from the contaminants. The CNS, a commercial product of technical grade, produced by Polish copper smelters, had been previously, before its further extractive purification treatment, prepared by leaching and dissolution in deionised water and by preliminary hydrometallurgical (oxy-hydrolytic) purification from iron(II), iron(III), arsenic(III), arsenic(V) and similar elements. Pilot apparatus with continuous flow of all media, applied to the CNS purification, consisted of 5 extractors of the mixer-settler type, joined together to make adequate counter-current system 1-2-0-2. Washing of the organic phase had not been applied because of purposeful preparation of the system merely for common, not selective, collecting of all metal ions, contaminating CNS. The system has reached an excellent purification level of nickel(II) sulphate. Obtained, as an additional product, the cobalt(II) sulphate concentrate (stripped solution) was almost totally neutralised (pH > 3.5).