An original strategy and evaluation of a reaction mechanism for recovering valuable metals from zinc oxide dust containing intractable germanide.

A novel leaching-roasting-leaching strategy was used to recover valuable metals from zinc oxide dust containing intractable germanide. In the ultrasonic enhanced oxidation leaching stage, potassium permanganate and ultrasonication were introduced to strengthen the dissolution of sulphide. During the roasting stage, sodium carbonate and magnesium nitrate were added to promote the reaction between the insoluble tetrahedral germanium dioxide and complex forms of germanium-containing compounds. Simultaneously, the sulphur produced in the ultrasonic enhanced oxidation leaching stage was used to change the phases of tin dioxide and zinc ferrite, thereby releasing germanium into its lattice. Finally, the germanium in the roasting slag was recovered by conventional leaching, and the grades of lead and tin in the residue were enriched to 35.21% and 11.31%, respectively. Compared with the conventional acid leaching process of enterprise, the total reaction time of this method was shortened to 80 min, and the recovery rates of zinc and germanium increased by approximately 10% and 40%, respectively. The entire process is clean and environmentally friendly and does not cause adverse effects on the recovery of lead and tin. Overall, this study provides new insights into the design of valuable metal recovery methods for zinc oxide dust containing intractable germanide.