Separation Science and Technology, Vol.39, No.10, 2441-2455, 2004
Selective separation of zinc and iron from spent pickling solutions by membrane-based solvent extraction: Process viability
This work reports the viability of the selective separation of zinc from spent pickling solutions by means of membrane-based solvent extraction to get a high concentrated zinc solution with a negligible content of iron and other metals that could be used in a electrolytic process to recover zinc in a metallic form. By working with waste effluents as feed solutions that contained these main components, Zn 78 g/L av., Fe 90 g/L av., and HCl 237 g/L av., Tributyl phosphate (TBP) and water were selected as the extractant and back-extraction agent that allowed maximum zinc separation and recovery. With the kinetic results obtained in a bench-scale set-up containing two hollow fiber (HF) modules the selectivity of zinc over iron recovery, alpha(Zn/Fe), was calculated. The parameter alpha(Zn/Fe), depended on the initial metallic concentration in the feed solutions and reached a maximum value of alpha(Zn/Fe) = 146 (g Zn/g Fe).