China Nonferrous Metallurgy

In recent years, the sources of zinc concentrate in the Northwest Lead Zinc Smelter have been complex and variable, with high residual sulfur and ferrous content in the calcine, more manganese ore powder needs to be added to reduce ferrous ion, resulting in an increase in the manganese ion content of the system and an increase in the unit consumption of electrolytic current. Based on this, a combined oxidation technology of manganese dioxide and hydrogen peroxide was proposed for iron removal, and a single factor conditional test method was used to investigate the effects of solution pH, leaching temperature, and combination of oxidant manganese ore powder and H₂O₂ in different proportions on the oxidation rate of precipitated alum supernatant solution. The results showed that the optimal conditions were as follows: the pH value of the solution endpoint was controlled between 4.8 and 5.2, the leaching temperature was 60 to 70℃, the amount of manganese ore powder added to the oxidation tank was 0.6 times the theoretical amount, the amount of oxidant H₂O₂ added was 1.0 to 1.3 times the theoretical amount, and the oxidation rate was optimal. The oxidation rate of Fe²⁺ was 92%, and the measured manganese ion in the solution was 5-6g/L. In production, the manganese content is maintained at 3-6g/L, and the direct current consumption per ton of zinc can be maintained below 3000kwh. Calculated based on an annual production of 220000 tons of cathode zinc, economic gain of 1.949 million yuan can be generated. The successful application of this technology has played a positive role in improving the indicators of zinc hydrometallurgy.