Solvent extraction of gallium with non-ionic surfactants from hydrochloric acid solution and its application to metal recovery from zinc refinery residues

Studies have been conducted on the solvent extraction of gallium from hydrochloric acid media with three chlorinated organic solvents containing a non-ionic surfactant, polyoxyethylene nonyl phenyl ether (PONPE), as an extractant. The extraction of allium(III) improved with an increase in HCl concentration, while that of other heavy metals except iron was suppressed in the whole acid range studied, resulting in the selective recovery of gallium. Effects of the diluent and the number of ethylene oxide (EO) units in the surfactants were also investigated on the efficiency of extraction. Moreover, the method was applied to acid leaching solutions of zinc refinery residues, which contain large amounts of zinc and iron than that of gallium. Experimental factors examined were hydrochloric acid concentration, combination of the diluent and the surfactant, and addition of a reducing agent for suppressing the extraction of iron. An overall solvent extraction process consisting of five scrubbing and one stripping stages has been proposed: the final recovery of gallium and iron was 71 and 1%, respectively. (C) 2003 Elsevier B.V. All rights reserved.