Fluidizing reduction roasting of low grade pyrolusite

Contrast experiments between fluidizing reduction roasting and muffle furnace static roasting were performed with a fluidized bed and a muffle furnace. It is found that the former is obviously better in terms of roasting time and reduction efficiency. CO and N₂ were used as reducing gas and fluid medium in fluidizing reduction roasting, respectively, and the effects of operation parameters such as roasting temperature, roasting time, and reducing atmosphere on the reduction efficiency were analyzed. When the roasting temperature is 800℃, the roasting time is 3 min, and the volume fraction of CO is 10%, a reduction efficiency of greater than 97% for MnO₂ in pyrolusite can be achieved. The reduction kinetics was also investigated, and it is confirmed that the reduction process is controlled by interface chemical reaction. The apparent activation energy of the reduction is about 38.817 kJ·mol^-1.