China Nonferrous Metallurgy

In recent years, the gradual depletion of zinc ore resources has led to a decline in the grade of most zinc concentrates in the world, and the scale of mining and utilization of low-grade zinc minerals has gradually expanded. However, the composition of low-grade ore is complex. After pretreatment and leaching, there are still many impurities accompanied by zinc ions entering the solution, causing anode corrosion, increasing power consumption, and affecting the surface morphology of precipitated zinc. In this paper, the corrosion mechanism of manganese ion, aluminum ion, iron ion, sulfate ion, bromide ion, fluoride ion and chloride ion on anode materials in zinc electrowinning is analyzed, and the removal methods of each impurity ion are given. The corrosion of fluorine and chloride ions to the anode is relatively obvious. Both of them corrode the anode by destroying the lead dioxide oxide film on the surface of the lead anode. The literature results show that the F^- concentration in zinc electrolyte should not exceed 0.03g/L, and the Cl^- concentration should be controlled below 0.1g/L. In the process of zinc electrowinning, the concentration of F^- and Cl^- should be reduced as much as possible, and anode materials that can resist F^- and Cl^- corrosion should be used.