Extraction of Manganese from Manganese Dioxide Ores by (NH4)2SO3 Reduction Roasting.

Manganese dioxide in pyrolusite was directly reduced to manganese sulfate by high-temperature roasting with ammonium sulfite as reducing agent, so as to achieve efficient extraction of pyrolusite. The effects of mass ratio of ammonium sulfite to pyrolusite, roasting temperature and time, leaching temperature and time on the extraction rate of manganese were investigated, and the optimum process conditions were determined. The results show that the optimal conditions are the mass ratio of ammonium sulfite to pyrolusite of 0.75:1, roasting temperature of 500 °C, roasting time of 1.5 h, leaching temperature of 25 °C, leaching time of 30 min. Under the conditions, the leaching rate of manganese and iron is about 93% and about 9.5%, respectively. The extraction effect of manganese is good. [ABSTRACT FROM AUTHOR]