Recovery of germanium from synthetic leach solution of zinc refinery residues by synergistic solvent extraction using LIX 63 and Ionquest 801

•The SSX system of LIX 63 and Ionquest 801 is highly selective for Ge.•Germanium is extracted from a strong acidic sulphate solution.•Germanium can be readily stripped using a weak base solution.•The germanium stripping kinetics was very fast.•The phase separation in both extraction and stripping is fast.

A synergistic solvent extraction (SSX) system consisting of LIX 63 and Ionquest 801 was identified and developed to recover germanium from a synthetic leach solution of zinc refinery cementation residues. A significant synergistic effect was identified with this novel SSX system, which selectively extracted germanium over other metals in the synthetic leach solution. The SSX system consisting of 0.13 M anti-oxime from LIX 63 and 0.13 M Ionquest 801 in ShellSol 2046 is an optimised composition for the extraction of germanium from the synthetic leach solution containing 1 g/L Ge(IV) and 1.0 M H2SO4.The germanium(IV) extraction kinetics was slow with the equilibrium reached after 20 min of mixing at 40 °C. The stripping kinetics of germanium(IV) with strip solution containing 0.5 M NaOH and 1.0 M Na2SO4 was very fast with the equilibrium reached in 1 min of mixing.Slope analysis showed that, most possibly, the extracted Ge(IV)-organic species is 2Ge(SO4)2·(HA)·(HB)2·H2SO4 via a solvating mechanism with the SSX system consisting of Ionquest 801 (HA) and LIX 63 (HB).