Extracting Gallium and Germanium from Zinc-leaching Residues by Hot-acid Leaching Process

Extraction of gallium and germanium from zinc leaching residue was carried out by hot-acid leaching.The effects of leaching agent(sulfuric acid),leaching temperature,leaching time,L/S ratio and agitation speed on the leaching rate of Ga and Ge were examined,while the thermodynamics and dynamic mechanism for the leaching were also analyzed.Results showed that the optimal leaching conditions were as follows: the initial mass concentration of sulfuric acid was 188 g/L,leaching temperature was 95 ℃,leaching time was 3 h,L/S ratio was 5∶1,and agitation speed was 300 r/min.Under these conditions,the leaching rates of Ga and Ge in acid leaching solution from multi-group comprehensive tests were averagely above 86% and 62%,respectively.Furthermore,the leaching process of Ga and Ge follows the kinetic law of shrinking of unreacted core,mainly influenced by leaching temperature,concentration of sulfuric acid and leaching time,also being controlled by interface chemical reaction.