Thermogravimetry and Reaction Gas Analysis of the Carbothermic Reduction of Titanomagnetite Ores with Char

Abstract

The carbothermic reduction of titanomagnetite (TIM) was investigated from a kinetic viewpoint in the temperature range of 1 000 to 1 150 degrees C employing thermogravimetric analysis (TGA) and quadruple mass spectrometry (QMS). The method of evaluating the fractional reduction in the carbothermic reduction of TIM by TGA was validated. The carbon in char consumed for the reduction of TIM was fully gasified into CO and CO2, which indicates that the TGA can be coupled to QMS from the viewpoint of mass balance of carbon. The carbon gasification reaction was activated when the Fe3O4 in TIM, wustite and Fe coexist at the fractional reduction of 0.21, indicating that Fe-catalyzed nature of Fe was confirmed for the carbon gasification. The activation energy for the reduction in TIM to wustite was evaluated to be 241 kJ/mol and the initial reduction stage is believed to be limited by carbon gasification. In the current study, it was considered that the changeover in reaction mechanism might be carried out from carbon gasification to the reduction in wustite to Fe by CO during the isothermal reduction of TIM with char.