Process mechanism research on direct vortex melting reduction of vanadium–titanium magnetite

Abstract

In response to the new mechanism of direct vortex melting reduction of vanadium–titanium magnetite, the reaction control mechanism and the migration regularity of valuable components in the process of direct melting reduction were investigated using kinetic empirical equation by fitting and combining with X-ray diffraction, X-ray fluorescence, scanning electron microscopy, energy-dispersive spectrometry, and optical microscopy. The results show that iron reduction is controlled by the mass transfer process of (FeO_x) in the slag, while vanadium reduction is controlled by both the mass transfer of (VO_x) in the slag and the mass transfer of [V] in the molten iron, and the slag–metal interfacial reaction is the only pathway for vanadium reduction. The reduction of iron and vanadium is an obvious first-order reaction, with activation energy of 101.6051 and 197.416 kJ mol⁻¹, respectively. Increasing the vortex rate and reaction temperature is beneficial to improving the reaction rate and reduction efficiency. The mineral phase variation of iron and vanadium in the slag during the reduction process is Fe₂O₃ → Fe₃O₄/FeV₂O₄ → FeTiO₃ and FeV₂O₄ → MgV₂O₅; titanium in slag is mainly in the form of Mg_xTi_3−xO₅ (0 ≤ x ≤ 1) and CaTiO₃. As the reaction time went on, the molar ratio (n_Ti/n_Mg) in Mg_xTi_3−xO₅ (0 ≤ x ≤ 1) and the Ti₂O₃ content in the slag gradually went up, while the area proportion of Mg_xTi_3−xO₅ (0 ≤ x ≤ 1) went up and then down, and the porosity of the slag and the grain size of Mg_xTi_3−xO₅ (0 ≤ x ≤ 1) got smaller.