Carbothermic Reduction Mechanism of Vanadium-titanium Magnetite

Abstract

To achieve the high-efficiency utilization of vanadium-titanium magnetite (VTM), reduction experiments were conducted to determine the carbothermic reduction mechanism of VTM. Effects of volatile matter, temperature, time, and carbon ratio (molar ratio of fixed carbon in coal to oxygen in iron oxides of VTM) on reduction degree were investigated. Results show that reduction degree increases with increasing volatile matter in coal, temperature, time, and carbon ratio. Phase transformation, microstructure, and reduction path were analyzed by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and FactSage 6.0. The thermoravimetry-differential scanning calorimetry-quadrupole mass spectrometer method was used for kinetic analysis of the main reduction process. Results indicate that the kinetic mechanism follows the principle of random nucleation and growth (n=4), and the activation energy values at 600–900 and 900–1350 °C are 88.7 and 295.5 kJ/mol, respectively.