Kinetics and mechanism of coal-based direct reduction of high-chromium vanadium–titanium magnetite

High-chromium vanadium–titanium magnetite (HCVTM) is a valuable resource containing metal elements such as iron, vanadium, titanium, and chromium. To recycle these elements, direct reduction is an efficient way. The mechanism and reaction kinetic parameters for the direct reduction of HCVTM were studied. Experimental results show that the reduction degree increases obviously when the C/O ratio and temperature increase. Thermodynamic analysis showed a dramatic mass loss in the direct reduction of HCVTM in the temperature range of 985–1160 °C. From 1200 to 1350 °C, the reduction curves for the isothermal reduction of HCVTM followed the same trend, with a sharp increase in the initial reaction zone and a slight increase in the reduction rate with increasing time, and finally, the isothermal reduction process of HCVTM was divided into several limiting stages with varying degrees, with inconsistent limiting factors for the reaction rate at different stages. The results also show that the activation energy decreases slightly at larger degrees of reduction. Also, the apparent rate constant k(T) increased with increasing reduction temperature, with lnk(T) showing a good linear relationship with temperature.