Study on behavior of reductive leaching of zinc from neutral leaching residue in zinc smelting

The paper describes the behavior of reductive leaching of zinc from neutral leaching residue in zinc smelting. The effective reductant of hydrazine sulfate was selected by investigating the extraction efficiency of zinc from neutral leaching residue in zinc hydrometallurgical process among various types of reductant， and the effects of initial concentration of hydrazine sulfate and sulfuric acid， retention，temperature and liquid-solid ratio on extraction were also studied. Furthermore the transformation of zinc phases during the leaching was illustrated. The sulfate， oxide， silicate and sulfide of zinc was extracted fast at first and zinc ferrite was mostly leached out after 120 min reaction. The leaching efficiency of Zn and Fe were 95.83% and 94.19% respectively in optimum conditions.