Effect of Hydrogen-Rich Atmosphere on the Reduction Behavior and Kinetics of Iron-Ore Pellets Under Non-isothermal Conditions

The effect of non-isothermal reduction processing of iron-ore pellets under different atmospheres was experimentally investigated under the conditions of a simulated blast-furnace lumpy zone (below 1100°C), and the kinetic mechanism and microscopic morphology were analyzed. The results show that the reduction starting temperatures were increased by 38°C and 54°C for the traditional blast furnace (TBF) and oxygen blast furnace (OBF) conditions, respectively, under hydrogen-rich conditions. In addition, the direct reduction starting temperatures were decreased by 6°C and 17°C for TBF and OBF conditions, respectively, under hydrogen-rich conditions. At 1100°C, the reduction degree of the pellets under TBF and hydrogen-rich TBF conditions was 68.95% and 76.85%, respectively, while under OBF and hydrogen-rich OBF conditions the reduction degree was 95.21% and 100%, respectively. In addition, kinetic analysis found that the reaction is first controlled by the chemical reaction, and then gradually controlled by the chemical reaction and internal diffusion. Increasing the H 2 content in the gas mixture not only increases the effective diffusion coefficient and reaction rate constant, but also weakens the effect of temperature on the resistance transit point at each stage.