Thermodynamic studies on gas-based reduction of vanadium titano-magnetite pellets

Numerous studies have focused on the reduction thermodynamics of ordinary iron ore; by contrast, the literature contains few thermodynamic studies on the gas-based reduction of vanadium titano-magnetite (VTM) in mixed atmospheres of H-2, CO, H2O, CO2, and N-2. In this paper, thermodynamic studies on the reduction of oxidized VTM pellets were systematically conducted in an atmosphere of a C-H-O system as a reducing agent. The results indicate that VTM of an equivalent valence state is more difficult to reduce than ordinary iron ore. A reduction equilibrium diagram using the C-H-O system as a reducing agent was obtained; it clearly describes the reduction process. Experiments were performed to investigate the effects of the reduction temperature, the gas composition, and two types of iron ores on the reduction of oxidized VTM pellets. The results show that the final reduction degree increases with increasing reduction temperature, increasing molar ratio of H-2/(H-2 + CO), and decreasing H2O, CO2, and N-2 contents. In addition, the reduction processes under various conditions are discussed. All of the results of the reduction experiments are consistent with those of theoretical thermodynamic analysis. This study is expected to provide valuable thermodynamic theory on the industrial applications of VTM.