Experimental Study on Zinc Germanium Leaching of High-Silicon Zinc Oxide Dust

Extraction processes of zinc and germanium from high-silicon zinc oxide dust have low metal recovery rates. This is mainly due to the acid leaching system, where the silicate in the soot easily hydrolyzes to form silica gel. This gel has strong adsorption properties and can adsorb zinc and germanium during leaching, causing them to co-precipitate into the slag and reducing the leaching rate. In this study, sulfuric acid was utilized as the leaching medium, an ultrasonic field was introduced to enhance the leaching process, and sodium Lauryl Sulfonate (C₁₂H₂₅SO₃Na) (activator) was included as a leaching aid. The effects of the main factors such as initial sulfuric acid concentration, activator concentration, liquid-to-solid volume mass ratio, leaching time, leaching temperature, and ultrasonic power on the leaching rate were investigated to determine the optimal leaching conditions. Results indicated that a sulfuric acid concentration of 180 g/L, activator concentration of 4 g/L, liquid–solid volume mass ratio of 7, leaching time of 60 min, and ultrasonic power of 360 W at 70 °C led to the highest metal leaching rates of 96.29% and 81.38% for zinc and germanium, respectively. Removal of the ultrasonic waves and activator resulted in an approximately 12% decrease in both zinc and germanium leaching rates, while other leaching conditions remained constant.