Strengthening mechanism of synergistic extraction of aluminum and gallium from coal gangue

Aiming at the problems of high quartz content, high ash content and difficult leaching of aluminum and gallium in some coal gangue, NaF-strengthened coal gangue calcination-hydrochloric acid leaching process was adopted, and the occurrence state of gallium in coal gangue was explored. The residue was analyzed by XRD and SEM, and the mechanism of NaF-strengthened coal gangue acid leaching was explored. The results show that the addition of m (NaF): m (coal gangue) = 0.06 can increase the leaching rate of aluminum in coal gangue from 33.72% to 62.03%, and the leaching rate of gallium from 43.17% to 70.15%. NaF as an additive can react with hydrochloric acid to form HF to destroy the coal gangue structure, so that hydrochloric acid can react with metakaolinite inside the quartz accumulation layer, which improves the leaching rate of aluminum and gallium. Finally, the process factors were studied separately to reveal the pattern in response to them, and it was found that the acid leaching reaction was greatly affected by internal diffusion, which provided a reference for the subsequent complexation adsorption of gallium.