Process optimization and mechanism of high-efficiency germanium extracting from zinc oxide dust containing germanium enhanced by ultrasound

Aiming at the problem of low extraction efficiency of germanium in zinc oxide dust, a process of strengthening germanium leaching by ultrasonic wave in sulfuric acid leaching process was proposed. The effects of acidity, temperature, time, liquid-solid ratio, ultrasonic power and amount of iron powder on germanium leaching were investigated by response surface method, and the ultrasonic enhanced leaching process was optimized. Based on process mineralogy analysis, and germanium phase distribution analysis, which is obtained by self-establishment step-by-step extract method, the studied zinc oxide dust contains 94.1% germanium oxide and germanate, 5.13% germanium sulfide and 0.77% insoluble germanium. The results showed sulfuric acid concentration 131 g/L(1.34 mol/L), temperature 78 °C, time 22 min, liquid-solid ratio 7.6:1, ultrasonic power 270 W, iron powder content 0.71%. The leaching efficiency of germanium is 95.19%, which is 5.79% higher than that of conventional leaching method. It was found that ultrasound can destroy the particle size, reduce the cluster structure of leached products by 13.5%, inhibit the agglomeration of particles, and promote the leaching of germanate and germanium sulphide. This study is of great significance for the production of germanium.