Phase Transformation of MnO_2 and Fe_2O_3 Briquettes Roasted Under CO-CO_2 Atmospheres

摘要

With the depletion of rich manganese ores, high-Fe content manganese ores are becoming the mainstream resources for manganese extraction. Reduction roasting-magnetic separation process is reported as a relatively effective route to realize the separation of manganese and iron. This study investigated the phase transformation of MnO_2 and Fe_2O_3 briquettes (molar ratio 1:1) roasted under various temperatures and CO-CO_2 atmospheres. Results showed that when the CO content was in the range of 0-10 vol%, Mn_xFe_(3_x)O_4 (x = 0-1) phase was formed and its content increased with the rising of temperature. The formation of ferromagnetic Mn_xFe_(3-x)O_4 with strong magnetism resulted in an inferior separation of manganese and iron by magnetization roasting-magnetic separation process. With the increase of CO content to over 25 vol%, the Mn_xFe_(3-x)O_4 content decreased while the content of feebly magnetic substance (MnO)_y(FeO)_(1-y)(y = 0-1) increased. Further increasing the CO content to over 80 vol%, (MnO)_y(FeO)_(1-y) was reduced to MnO and metallic iron.