Selective separation of gallium-aluminum from gallium depleted electrolyte by calcium salt de-alumination and resin adsorption

Gallium, as a strategic rare metal, is often associated with elements such as zinc and aluminum. In the oxygen-pressure zinc hydrometallurgical system, gallium is typically recovered through a leaching-enrichment-extraction-electrowinning process. The gallium concentration of the depleted solution after electrowinning is generally 5~10 g/L. The aluminum concentration can reach as high as 25 g/L, and the accumulation of recycled aluminum increases the burden of gallium electrowinning and reduces gallium quality. For this reason, this study designed a calcium oxide de-alumina-resin (ZGD887) adsorption of gallium de-alumina / gallium-rich double-effect process, with the gallium electrowinning depleted solution provided by an enterprise as the raw material, to explore the optimal conditions of calcium oxide de-alumina, and examined the effect of adsorption conditions on the gallium performance of the resin adsorption of de-alumina solution after the performance of gallium. The results showed that calcium oxide could induce the conversion of aluminum to calcium aluminate hexahydrate in the electro-gallium depleted solution, thereby achieving aluminum removal. Under conditions of a temperature of 90 ℃, a reaction time of 120 min, and twice the theoretical mass of calcium oxide, the precipitation efficiency of aluminum reached 92.44% and the loss efficiency of gallium was only 12.60%. Then, under adsorption conditions of 30 ℃, resin dosage of 0.1 g/mL, and oscillation rate of 250 r/min, the total recovery efficiency of gallium reached 83.05% after four adsorption cycles. By applying the calcium salt de-aluminized resin adsorption method, the aluminum removal rate was 92.44% and the comprehensive gallium recovery rate was 72.59%, achieving open-circuit of aluminum in the electro-gallium lean solution and efficient enrichment of low-concentration gallium.