Extraction behavior of germanium in different leaching systems from zinc oxide dust

The leaching behaviors of valuable metals such as Zn, Fe, Pb and Ge in the cycle leaching processes of sulfuric acid, oxalic acid, tartaric acid and the mixture of,sulfuric and tartaric acid were investigated, with germanium-containing zinc oxide dust as raw material. The results show that the high-efficiency extraction of Ge and Zn can be achieved by using a sulfuric acid leaching process. Under the conditions of sulfuric acid concentration of 100 g/L, temperature at 90 ℃, liquid-solid ratio of 10 mL/g, and the reaction time of 120 min, the leaching ratios of Ge and Zn can reach 86.12% and 93.13%, respectively. The selective separation of Ge and Fe from Zn and Pb can be achieved by the oxalic acid leaching process, and under optimal conditions, the leaching ratios of Ge and Fe are respectively 92.32% and 67.30% while Pb and Zn are essentially not leached. The leaching ratio of Ge in the tartaric acid leaching process is relatively low, reaching a maximum of 76.15%, while the leaching ratios of Zn and Fe remain at a low level. The leaching ratio of Ge in the mixed acid leaching process of sulfuric acid and tartaric acid improves significantly, up to 99.42%. Meanwhile, the leaching ratios of Zn and Fe are up to 89.53% and 68.56%, respectively. The concentration of Ge can reach 152.93 mg/L by four-stage cyclic leaching. The extraction ratio of Ge can reach almost 90% with the separation of the N235 extractant.