Effect of Impurities on the Hydrogen Reduction Kinetics of High-Phosphorus Iron Ore
Insights from a Hematite-Based Comparative Analysis
Yubo Zeng (Wuhan University of Science and Technology)
Wu Zhou (Wuhan University of Science and Technology)
Yi Su (Wuhan University of Science and Technology)
Weizhe Jie (Wuhan University of Science and Technology)
Yang Li (Wuhan University of Science and Technology, Vlaamse Instelling voor Technologisch Onderzoek)
Hua Zhang (Wuhan University of Science and Technology)
Hongwei Ni (Wuhan University of Science and Technology)
Zhiyuan Chen (Vlaamse Instelling voor Technologisch Onderzoek)
Yongxiang Yang (TU Delft - Mechanical Engineering)
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Abstract
High-phosphorus iron ore (HPIO) is a refractory ore due to its high phosphorus content and complex mineral phase structure. Hydrogen reduction has emerged as a promising technology for its superior performance. In this study, using hematite as a reference, the reduction kinetics and reaction mechanisms of HPIO under a hydrogen atmosphere were investigated via non-isothermal kinetics, with a particular focus on the influence of gangue minerals on the reduction behavior. The results indicated that the reduction process of HPIO differed significantly from hematite due to carbonate gangue decomposition and oolitic structure. Based on conversion rate (α) analysis, the reduction process of HPIO was reclassified into four distinct stages, whereas hematite reduction occurred in three stages. In the first three stages of HPIO, the most likely reaction kinetic mechanisms were the 1.5th-order reaction model (F1.5), the 3rd-order reaction model (F3), and the three-dimensional Jander diffusion model (D3), with corresponding activation energies of 67.05 kJ/mol, 70.36 kJ/mol, and 122.27 kJ/mol, respectively. Correspondingly, the rate-limiting step transitioned from the surface-to-interior gradient reduction process to intraparticle hydrogen diffusion. This transition was collectively driven by oolitic gangue phases, densification of the surface iron layer, and CO2 generated from carbonate decomposition, which synergistically hindered hydrogen diffusion within the particles.