Abstract: The precipitation process was studied for preparing high purity manganese oxide with the industrial manganese sulfate solution containing magnesium ion of high concentration as raw material.Through determining the concentrations of manganese ion and magnesium ion in the filtrate and calculating the mass ratio of magnesium/manganese in the precipitate， the effects of the initial concentration of manganese sulfate solution，precipitation pH，and reaction temperature on the pre- cipitation behavior of manganese and magnesium ion were investigated.Results showed that the precipitation rate of man- ganese was up to 90% when the mass concentration of Mn in manganese sulfate solution was 40 g/L（the mass concentration of magnesium was 1.56 g/L），the final pH was 9.0，and the reaction temperature was 40 ℃.Moreover，the obtained manganese oxide product′s manganese mass fraction was 71%，magnesium mass fraction was 2×10-4，zinc mass fraction was 1.26×10-4， and other metallic element mass fractions were all less than 7×10-5，which basically could meet the purity requirements of the manganese oxide product.

Key words: manganese sulfate solution, magnesium precipitation, Mn3O4