Kinetic study on carbothermic reduction of MnO2 with graphite

The carbothermic reduction of MnO₂ with graphite has been investigated for the reduction mechanism in the temperature range of 1000–1300°C. Although several researchers studied the reduction step from MnO₂ to MnO, it was attempted to employ the in situ testing of reduction behaviour with the analysis of product gas composition simultaneously from the different points of view. The overall reduction rate increased with temperature, which was controlled by the carbon gasification. It is because the reduction rate of MnO₂ to MnO was much faster than the carbon gasification at the experimental temperatures. This was confirmed by the generation of negligible amount of CO compared with CO₂ in the analysis of product gases. Furthermore, the results could explain the difficult formation of manganese carbide from MnO₂ in contrast with the carbide formation from pure MnO.