Preparation of High Purity Manganese Sulphate from Low-Grade Rhodochrosite

Abstract

In our work, the preparation technique of high pure manganese sulfate directly from low-grade rhodochrosite ore (MnCO 3 ) was studied and improved intensively, including the effective leaching process and the short purifying process. Based on the same ion effect, the repeated leaching of rhodochrosite with sulfuric acid is proposed to improve the solubility of Mn 2+ and inhibit the dissolution of the impurities Ca 2+ and Mg 2+ . Moreover, the repeated leaching process could make full use of rhodochrosite and lower the dosage of sulfuric acidas raw material. With the aid of theoretical calculation, Ba(OH) 2 was chose to adjust the pH value of manganese sulfate solution, and BaF 2 to remove Ca 2+ and Mg 2+ completely in the process of purifying. The results demonstrate that the extraction ratio and the recovery ratio of manganese reached 94.3% and 92.7%, respectively, which shows the prospect of industrial application. In manganese sulfate production, the heavy metal impurities have been decreased to less than 1ppm. Moreover, the content of calcium, magnesium and sodium has been decreased to less than 20ppm, which meets the standards of high pure reagent for energy and electronic materials. Our study enlightens an approach to the sustainable application of low-grade rhodochrosite.