2017 Volume 57 Issue 4 Pages 609-614
Several studies have examined the reduction behavior of manganese ore at high temperature with the aim of reducing the manganese cost in the steelmaking process. However, the transformation behavior of manganese compounds at high temperatures had not yet been clarified. Therefore, in this paper, the effects of temperature and oxygen partial pressure, as well as chemical composition, on the transformation and melting behavior of manganese ore were investigated by using high temperature X-ray diffraction (XRD) and thermogravimetry-differential thermal analysis (TG-DTA) in order to obtain fundamental information on the pre-reduction process of manganese ore. The main manganese compound in the raw manganese ore used in this study was characterized as CaMn6SiO12 by XRD at room temperature, while the main Mn compounds in the sintered manganese ore were Mn3O4 and MnO. Under a vacuum condition, raw manganese ore and sintered manganese ore were reduced to MnO above 1473 K. However, under atmospheric conditions (pressure: 760 Torr), manganese ore was reduced to Mn3O4 rather than MnO at temperatures above 1073 K. The results of high temperature XRD agreed with thermodynamic calculations. The melting temperature of the raw manganese ore evaluated by TG-DTA was lower than that of the sintered manganese ore due to the difference in the manganese oxide in each ore rather than the difference in the content of gangue components such as Al2O3, CaO, MgO and Fe2O3. The higher melting temperature of the sintered manganese ore is interpreted in terms of a higher content of MnO due to heat treatment.