Green and efficient recovery of valuable metals from by-products of zinc hydrometallurgy and reducing toxicity

Germanium-containing dust as an intermediate by-product in the process of zinc hydrometallurgy, which often contains a large number of heavy metal substances. Due to the constraints of economic benefits and process technology, green and efficient treatment of germanium-containing dust is always a great challenge. In this work, XRD, ICP-OES, XPS, SEM and other characterization methods were used to analyze the existing state and quantity of main substances in germanium-containing dust. It was found that the occurrence state of germanium was closely related to sphalerite. At the same time, longer reaction time would lead to continuous hydrolysis of silicate, which would eventually affect the recovery of zinc, germanium and lead and the fixation of toxic substances. Therefore, the ultrasonic enhanced ammonium persulfate oxidation process was proposed to control the waste of resources and environmental pollution caused by the accumulation of germanium-containing dust. The final results showed that more than 95% of zinc and 89% of germanium were efficiently recovered, and heavy metals such as arsenic and cadmium were fixed in the liquid, and then concentrated in the purification and impurity removal stage. The residue after reaction is high-grade lead sulfate residue, which can be returned to the lead smelting system for recycling. In summary, the ultrasonic-enhanced ammonium persulfate process eventually makes all substances in germanium-containing dust harmless and resource treatment. [Display omitted] •A green, energy-efficient process was designed to recover Zn and Ge.•The occurrence mechanism of ultrasonic wave and (NH4)2S2O8 was studied.•The migration rules of Zn and Ge in ultrasonic–(NH4)2S2O8–H2SO4 system was studied.•The recovery rate of Zn and Ge were increased by 10%, lead grade increased to 48%.