Abstract: In the process of leaching zinc oxide flue dust containing indium using sulfuric acid as lixiviant by oxidative pressure leaching in an autoclave, the effects of initial concentration of sulphuric acid, reaction time, temperature and the dosage of oxidant on leaching efficiency of indium were studied.The experimental results showed that both pressurizing and using potassium permanganate as oxidant can strengthen the indium extraction from zinc oxide flue dust.The leaching efficiency of indium was improved effectively by oxidative pressure leaching.The optimum conditions of pressure leaching were determined as 400 g/L sulfuric acid for 120 min at 120 ℃ with the dosage of oxidant was 4% of flue dust, and the stirring speed, ratio of liquid to solid, gauge pressure were 575 r/min, 8∶1, and 0.5 MPa, respectively.As a result, the leaching rate of indium can reach 90.6% under these optimum conditions.

Key words: Indium, Zinc oxide flue dust, Oxidative pressure, Leaching