Synergistic extraction of zinc from ammoniacal solutions using β-diketone mixed with CYANEX923 or LIX84I
(Key Laboratory of Resources Chemistry of Nonferrous Metals (Ministry of Education),
School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China)
School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China)
Abstract: The extraction behaviors of zinc from ammoniacal solutions were investigated using β-diketone (HA) and their mixtures with CYANEX923 or LIX84I. The effects of pH, total ammonia concentration, extractant concentration, anion species and temperature on zinc extraction were examined. The synergistic mechanism was discussed with regard to the structure of extractant and the extracted zinc complexes. It is found that the increase of total ammonia concentration and pH inhibits zinc extraction for all extraction systems due to the formation of zinc ammine complexes in aqueous phase. This effect of HA with CYANEX923 is evidently smaller than that of HA with LIX84I or HA alone system. Effect of anion species on the zinc extraction by HA with CYANEX923 can be neglected, but this effect of HA alone and the mixture of HA with LIX84I decreases in the order of (NH4)2SO4 > NH4NO3 > NH4Cl.
Key words: synergistic extraction; zinc; ammoniacal solution; β-diketone; CYANEX923; LIX84I