Efficient separation and recovery of gallium from GaAs scraps by alkaline oxidative leaching, cooling crystallization and cyclone electrowinning

In recent times, there has been a growing focus on the recovery of gallium from secondary resources. This study introduces an innovative hydrometallurgical process designed for the efficient recovery of gallium from GaAs scraps, incorporating alkaline oxidative leaching, cooling crystallization, and cyclone electrowinning. The alkaline oxidative leaching phase scrutinized the impact of various conditions on leaching efficiency. Optimized parameters, including a NaOH concentration of 33.3 g/L, H2O2 excess coefficient of 1.29, rotation speed of 150 rpm, L/S ratio of 4:1, and a reaction time of 40 min, resulted in an outstanding gallium leaching efficiency of 98.74%. Despite attempts with neutralization precipitation, the separation of gallium and arsenic proved challenging due to colloidal adsorption. However, effective separation was achieved through cooling crystallization. Subsequent purification of the cyclic lixivium and preparation of the dearsenic electrolyte via cooling crystallization followed. In the final step, cyclone electrowinning was implemented for gallium recovery from the dearsenic electrolyte. This phase yielded impressive results, with gallium purity reaching 99.993%, current efficiency at 34.43%, and an overall gallium recovery of 90.46%.