Optimizing Pre-reduction of Vanadium–Titanium Magnetite Through Recycling and Integrating of Top Gas from Melting Furnace and Tail Gas from Rotary Kiln

In this study, the pre-reduction impact of CO and H2 on vanadium–titanium magnetite (VTM) was examined considering the composition of the top gas of the melting furnace. Additionally, the recycled and upgraded tail gas from the rotary kiln was mixed with the top gas of the melting furnace to enhance the pre-reduction effect and meet the temperature requirements of the rotary kiln. By analyzing the variations in the tail gas composition, the possible reactions occurring during the VTM pre-reduction process were determined. The results demonstrate the crucial role of H2 in the reduction process. A 20% H2 concentration yields a reduction effect similar to that achieved with 55% CO, resulting in a complete reduction of magnetite. However, the presence of CO2 in the gas hinders the reduction reaction by decreasing the reduction capacity of CO or inducing a secondary oxidation of the reduction products. Furthermore, the introduction of half of the tail gas of the rotary kiln into the top gas of the melting furnace increases the metallization rate of VTM pellets from 37.84% to 57.2%. These findings provide valuable references for utilizing the high-temperature top gas of the melting furnace for VTM pre-reduction in rotary kilns.