Parameter Optimization and Reaction Kinetics of the Reduction of Vanadium–Titanium Sinter by CO–CO2–H2–N2 Mixed Gases

In this work, the reaction behaviors of vanadium–titanium sinter reduced by CO–CO₂–H₂–N₂ mixed gases were investigated in the range of 1123–1273 K. Different technologies, such as thermodynamic calculation, kinetics analysis, FESEM observation, and orthogonal design method, were adopted to analyze the experimental data. When regarding the reduction degree of raw material as the evaluation index, the findings demonstrated that the influence extent of different parameters was given as follows: temperature > H₂ > CO > CO₂. The work also found that the increase of reaction temperature and H₂ volume fraction had positive effects on improving the reduction degree, while the increase of CO and CO₂ volume fractions had opposite effects. Based on the result, the optimal parameters for the H₂-rich reduction of vanadium–titanium sinter were considered as 1223 K and a gas composition of 21% CO, 14% CO₂, 10% H₂, and 55% N₂. Kinetics analysis result showed that the reduction process was predominantly controlled by the interfacial chemical reaction between the unreacted raw material and H₂-rich gases, with the apparent activation energy extracted to be 78.63 kJ/mol. However, the gas diffusion may also play an important role due to the dense surface structure of reaction product.