Experimental Study on the Enhanced Leaching of Gallium and Germanium from Zinc Powder Replacement Residues
To solve the problem of poor leaching effeciency in the extraction process of gallium and germani-um from zinc powder replacement residues,this study first conducted atmospheric sulfuric acid leaching tests,investigating the influence of sulfuric acid concentration,reaction temperature,liquid-to-solid ratio,and reaction time on the leaching rates of Ga and Ge,and carried out kinetic analysis of the leaching process.Then,the enhanced leaching tests of Ga and Ge from zinc powder replacement residues were con-ducted by reduction leaching(sequentially using Na2SO3 and SO2 as reducing agents)and sulfation roast-ing-water leaching.The results show that under the optimum conditions of sulfuric acid concentration of 150 g/L,reaction temperature of 90 ℃,liquid-to-solid ratio of 5 mL/g,reaction time of 4 h,and stirring speed of 400 r/min,the leaching rates of Ga and Ge by atmospheric sulfuric acid leaching are 68.4％and 61.7％,respectively.The main phases in the acid leaching residue are PbSO4 and ZnAl2O4,and increasing acidity can further dissolve the residual jarosite and lead aluminum sulfate.The atmospheric sulfuric acid leaching processes of Ga and Ge are mainly controlled by internal diffusion with the apparent activation energies of the reactions of 18.06 kJ/mol and 16.02 kJ/mol,respectively.The leaching residue from the first stage of atmospheric sulfuric acid leaching underwent a second-stage reduction enhanced leaching.Using Na2SO3 as the reducing agent,Ga and Ge leaching rates reach 89.4％and 70.1％,respectively,under the conditions of 50 g/L H2SO4 and 3 g/L Na2SO3.And using SO2 as the reducing agent,Ga and Ge lea-ching rates reach 88.9％and 86.7％,respectively,under the conditions of SO2 partial pressure of 0.3 MPa,sulfuric acid concentration of 50 g/L,reaction temperature of 110 ℃,and reaction time of 3 h.The sulfation roasting-water leaching process significantly improves the Ga leaching efficiency from zinc powder replace-ment residues,while it is unfavorable to the leaching of Ge.Under the optimum conditions of acid residue volume-to-mass ratio of 1/2.5 mg/L,roasting temperature of 300 ℃,roasting time of 3 h,water leaching temperature of 80℃,liquid-to-solid ratio of 5 mg/L,and leaching time of 2 h,the leaching rate of Ga in-creases to 89.1％.
万方数据
维普
