Kinetics Analysis and Energy Utilization of Hydrogen Direct Reduction Iron in a Fluidized Bed: Influence of Iron Ore Composition

This study investigates how mineral crystal composition governs direct reduction iron (DRI) properties in hydrogen-based fluidized beds, focusing on Fe–O compounds and heteroatomic interactions. The reduction results for four ores indicate that the crystal phase and content of Fe–O compounds influence the final reduction degree and activation energy, leading to considerable differences in bonding behavior. Combined with energy analysis, it is evident that minerals with a reduction degree exceeding 80% exhibit lower energy consumption and a higher carbon emission reduction. Using response surface methodology, we systematically evaluated the effects of key mineral constituents on the reduction efficiency and product bonding. Fe₂O₃ exerts the most substantial positive influence on reduction degree, followed by Fe₃O₄, while Si/Al/Ca–O (>6%) dominantly triggers product adhesion. The interaction among Fe₂O₃–FeO, Fe₂O₃– Fe₃O₄, and Fe₃O₄–Si/Al/Ca–O leads to the decreased reduction degree, and Fe₂O₃, FeO, and Fe₃O₄ exhibit significant influence within the ranges of 0–15%, 4–10%, and 5–20%, respectively. These findings enable target ore selection and blending strategies for hydrogen-based DRI production, particularly for magnetite-rich or high-impurity feedstocks. The established predictive model supports real-time adjustment of mineral inputs to balance the reduction efficiency and operational stability, advancing the transition toward carbon-neutral ironmaking.