2018 Jinxia Zhang Atmospheric sulfuric acid leaching thermodynamics from metallurgical zinc bearing dust sludge ijht.360131

In this study, we systematically investigated the influence of zinc and iron reactions within a sulfuric acid leaching system, focusing on the parameters affecting the leaching of zinc sulfate and the subsequent leachate purification conditions. We identified that the primary zinc and iron phases in metallurgical zinc-bearing dust sludge include ZnO, ZnS, ZnFe2O4, Fe, Fe2O3, and Fe3O4. Analyzing the Zn-Fe-H2O system, we found that as the concentrations of zinc and iron ions in solution increased, the composition remained unchanged, with the dominant areas varying according to solution pH. Our results showed that controlling the potential and pH within specific ranges allowed for efficient separation of Zn and Fe at different levels; however, Fe2O3 was resistant to leaching with sulfuric acid. Notably, ZnO was leached while iron ion leaching was inhibited by pH adjustments. Furthermore, we determined that by adding an appropriate oxidant, Fe2+ could be oxidized to Fe3+, leading to the formation of Fe(OH)3 sediment with the addition of NaOH in solution, which effectively removes iron. These findings contribute significant theoretical insights into the leaching and purification processes relevant to alkali leaching-electrolysis applications.