Evaluation of Gaseous Reduction Rate of Magnetite Concentrate with Hydrogen at 1173 K

Abstract

Hydrogen-based ironmaking is one of the most promising technologies that does not emit CO₂ to achieve carbon neutrality in the ironmaking process. On the other hand, high-grade hematite iron ore with low gangue content has depleted. Magnetite iron ore can improve its grade by crushing, grinding, and magnetic separation. It is expected to be used as the primary iron source for hydrogen-based ironmaking by reducing its fine ore with hydrogen. In this study, magnetite concentrate was reduced with H₂-N₂ gas at 1173 K and the reduction rate was investigated. The time required to reduce fine iron ore to a fixed fractional reduction increased linearly concerning the ratio of iron ore mass to the flow rate of the reducing gas. The reduction rate, independent of the gas flow rate, was obtained from the results. It was found that the reduction rate of the magnetic particles in the fine iron ore was smaller than that of the non-magnetic particles and became significantly small at the reduction stage from Fe_1-yO to Fe. This difference is caused by pores forming only in the non-magnetic particles associated with the progress of gaseous reduction.