Leaching of gallium from corundum flue dust using mixed acid solution
(1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. School of Metallurgy and Environment, Central South University, Changsha 410083, China)
2. School of Metallurgy and Environment, Central South University, Changsha 410083, China)
Abstract: In order to extract gallium from a high-silica-content flue dust generated in corundum production, a mixed acid solution of H2SO4 and HF was used for leaching, and test parameters of the leaching process were optimized. Experimental results show that the leaching rate of gallium was only 38% when H2SO4 was used as leaching agent. Composition analysis results of micro areas in this corundum flue dust indicate that the content of gallium in silica-enriched phases was high; this portion of gallium was insoluble in H2SO4 solution. The leaching rate of gallium increased significantly with addition of HF due to corrosion of silica. Effects of reaction time, temperature, and concentrations of HF and H2SO4 on leaching rates of gallium were investigated. The leaching rate of gallium reached 91% when this corundum flue dust was leached in a mixed acid solution of H2SO4 and HF for 4 h, at a temperature of 80 °C, with a liquid-to-solid ratio of 5:1 (mL/g). The optimal concentrations of H2SO4 and HF in the mixed acid solution were 1.5 and 6.4 mol/L, respectively.
Key words: gallium; leaching; corundum flue dust; sulphuric acid; hydrofluoric acid; silica