Melting Separation Behavior and Mechanism of High-chromium Vanadium–bearing Titanomagnetite Metallized Pellet Got from Gas-based Direct Reduction

Abstract

The recoveries of vanadium, chromium, and titanium are much low in the current process of high-chromium vanadium–bearing titanomagnetite. The gas-based direct reduction followed by melting separation process was proposed because the valuable elements including iron, vanadium, chromium, and titanium can be utilized simultaneously and all the recoveries should increase. The melting separation study was carried out in the present work, and the behavior as well as mechanism during melting separation process was investigated. The effect of temperature on the melting separation kinetic was more considerable than thermodynamic. As increased basicity, the area of liquid phase was enlarged and the solubility of Al₂O₃ in slag was increased. The main mineral in separation slag was anosovite (MgTi₂O₅), besides a small number of pseudobrookite (Fe₂TiO₅), perovskite (CaTiO₃), and spinel (Ca₃Al₂O₆). The melting separation was improved by the increasing C/O, temperature, time, additive of CaF₂, and basicity. The rational melting separation parameters for high-chromium vanadium–bearing titanomagnetite contained a C/O of 1.2, a melting temperature of 1625°C, a melting time range of 40–50 min, an additive CaF₂ of 2%, and a basicity of 1.1. Under these conditions (melting time of 50 min), the melting separation was achieved successfully. Both the titanium-bearing slag together with the iron containing vanadium and chromium was obtained. The recoveries of Fe, V, Cr, and TiO₂ could reach around 99%, 97%, 92%, and 94%, respectively; and the mass fraction of Fe, V, Cr, and TiO₂ were 93.50%, 0.90%, 0.69%, and 37.52%, respectively.