Purification of nickel sulfate solutions via solvent extraction method

Abstract

This Thesis focuses on extractive separation of metal impurities from solution typical for hydrometallurgical nickel plants, containing nickel and cobalt. The research combines various experiments of residue metal extraction and provides an initial proposal of a solvent extraction process. Several classes of organic extractants, which are mainly applied in metals extraction were described in order to investigate the suitable extractant for Al, Mg, Mn, Fe, Zn, Ca ions: phosphorus-based acids, represented by Cyanex 272® (bis(2,4,4-trimethylpentyl) phosphinic acid), D2EHPA (di(2-ethylhexyl) phosphoric acid) and PC-88A (2-ethylhexyl phosphonic acid); hydroxyoximes (LIX 622N and LIX 84-I) and organic acids (Versatic 10). The main process steps, performed by loading, scrubbing and striping stages were considered. The other methods of nickel and cobalt purification at synthetic leaching liquor was considered. Alternative methods as oxidative precipitation and ion exchange were described comprising description of developed appropriate conditions, where ion exchange resin application was tested experimentally.