Solvent extraction separation of indium and gallium from sulphate solutions using D2EHPA

Solvent extraction and stripping experiments have been performed to separate indium from gallium in sulfuric acid solutions. In the extraction process, the separation factor between indium and gallium decreased with pH and a maximum value of the separation factor was obtained by extracting metals from the mixed solutions with stoichiometric concentration of di-2-ethyl-hexylphosphoric acid (D2EHPA) to extract both metals. It was found that aliphatic kerosene was superior to benzene as a diluent in respect of loading capacity. In the stripping process, the stripping percentage of indium decreased from 95% to 5% with pH in the pH range of 0.2–1.4, while separation factors increased with the pH of the stripping solutions. From simulation experiments for multistage countercurrent extraction, nearly complete separation of indium and gallium would be accomplished by a two-stage extraction.