Reduction kinetics of oxidized vanadium titano-magnetite pellets using carbon monoxide and hydrogen

The gas-based isothermal reduction kinetics of oxidized vanadium titano-magnetite (VTM) under the range of 1173-1323 K was investigated in this study. The influence of reduction temperature, gas composition and reduction time on reduction process were studied. Experiment results display that the reduction degree of pellets significantly increases with increasing of reduction temperature, reduction time and ratio of H2/(CO + H2). The kinetics study indicates that the early stage of gas-based reduction course is controlled by intrinsic chemical reaction and in the latter stage controlled by diffusion. The activation energies of the gas-based reduction for different gas atmosphere and different stage are studied. In addition, this study firstly presents that the diffusion-control step is significantly shortened with the increase of the ratio of H2/(CO + H2). SEM results indicate that pellet which was reduced in H2 atmosphere has a lot of inner pores (0-5 μm) in mineral grains. Inner pores provide gas channels and decrease gas diffusion resistance during the reduction process so that the diffusion-control step is shortened. These results can serve as a reference to the utilization of hydrogen and carbon monoxide on VTM ore.