Reduction kinetics and phase transformation mechanisms of hematite by H₂-Rich gas: A Multi-Stage reaction analysis

Hydrogen-rich ironmaking technology has the advantages of fast reaction rate and significant emission reduction effect, but the appropriate hydrogen-rich ratio governs the reduction efficiency of hematite. In this study, we utilized a thermogravimetric analyzer to investigate the reduction reaction characteristics of hematite particles in a hydrogen-rich atmosphere. In the temperature intervals of 650–750 and 800–900 °C, the reduction process was bifurcated into two stages, influenced by the lattice oxygen migration rate, with the reduction degrees of 0.23 and 0.33 marking the boundaries of each stage. Upon analyzing the physical phase composition of representative nodes and the proportional content of each constituent, it is determined that the discrete reduction steps of iron oxides take place nearly concurrently. Employing the kinetic calculation methods, it is determined that the peak in the activation energy trend aligns with the reduction degree threshold, signifying the commencement of the predominant reduction phase from FeO to Fe.