Research progress on gallium extraction from different secondary resources

As one of the rare metals, gallium enjoys vast application in the field of fiber communication, aerospace and electronic technique. Demand has far outstripped supply of gallium along with the development of the electronics industry. Gallium has no independent mineralization. Because some of its physical and chemical properties are similar to aluminum、iron and zinc etc. Gallium mainly exists in bauxite, lead zinc mine, coal and ilmenite. In the process of hydrometallurgical and pyrometallurgical processes of these minerals, gallium could be enriched in the by-products of alumina production, zinc-leaching residue from zinc hydrometallurgy process, fly ash in the process of coal combustion, e-waste and so on. With the increasing demand of gallium, how to regeneration of gallium from secondary resources has attracted a lot of attention recently. The paper mainly focuses on the occurrence and recovery of gallium in these secondary resources. These methods involve alkali-acid dissolution, hydro-thermal, solvent extraction, chlorination volatilization, vacuum distillation, reduction melting, and so on. The advantages and existing problems of all these processes are analyzed and evaluated. It provides reference for the extraction and recovery of gallium from these secondary resources.