A Review on Separation of Gallium and Indium from Leach Liquors by Solvent Extraction and Ion Exchange

Considering the growing demand for In(III) and Ga(III) for the manufacture of advanced materials, it is necessary to develop efficient separation processes for recovery of these metals from primary and secondary resources. In the present work, separation of In(III) and Ga(III) from different aqueous mediums by solvent extraction, ion exchange, and solvent-impregnated resins/gels was reviewed. Although complete separation of In(III) from Ga(III) is possible using ion exchange or solvent-impregnated resins/gels, these methods are limited in industrial applications due to low adsorption capacity for metals. Solvent extraction with amines, acidic, and neutral extractants is commonly employed to separate these two metal ions. Amines and neutral extractants can extract both In(III) and Ga(III) and then these metals are separated by selective stripping. By contrast, solvent extraction with acidic extractants including commercial and synthetic extractants results in complete separation of In(III) and Ga(III). Compared to common commercial extractants such as D2EHPA, PC88A, Cyanex 272, and Cyanex 301, synthetic extractants offer higher extraction and separation efficiency, but extraction kinetics and stripping efficiency in these systems should be improved in the future.