Leaching process of germanium oxide dust

A thermodynamic analysis on acid leaching process of germanium oxide dust and discussion on behaviors of main substances of dust in leaching process were carried out. The effects of temperature, acid concentration, leaching time and stirring speed on leaching rate of germanium were investigated. Based on characteristic of dust, kinetics and reactive mechanism of acid leaching were stud- ied. The results show that leaching of dust by acid belonged to the unreacted core shrinking model of producing solid outgrowth layer. The chemical reaction was controlled by inner diffusion process. The apparent activation energy of leaching process was 12.60 kJ/mol. The leaching reaction of germanium was determined to be mainly second order reaction. The optimum conditions were reaction tem- perature of 363 K, leaching time of 2.5 h, stirring speed of 120 r/min, solid-to-liquid ratio of 1/8 and acid concentration of 120 g/L. Under these conditions, leaching rate of germanium can come up to more than 87%.