Comparative numerical study of Fe2O3 reduction using CO and H2 for direct iron production

Abstract

This study presents a comparative analysis of Direct Reduced Iron (DRI) production using carbon monoxide (CO) and hydrogen (H₂) as reducing agents, modelled through Ansys Twin Builder. The simulations evaluate conversion efficiency, gas utilization, energy demand, and environmental performance under industrial-scale conditions. A simplified and idealized system is adopted, where iron ore pellets are assumed to be composed entirely of hematite (Fe₂O₃), with complete reduction to metallic iron (Fe) and negligible dust formation.

The model simulates the reduction of 300 tons of pellets per hour, corresponding to 206.25 tons of Fe₂O₃. Based on stoichiometric reactions (Fe₂O₃ + 3CO → 2Fe + 3CO₂ and Fe₂O₃ + 3H₂ → 2Fe + 3H₂O), the simulation estimates the production of approximately 144.2 tons of metallic iron per hour. For the hydrogen-based route, ∼104,200 m³/h of H₂ is required (including 20 % excess), resulting in a gas utilization efficiency of 83.3 %. Under the same conditions, the CO-based route emits approximately 1.18 tons of CO₂ per ton of Fe, while the H₂-based route achieves zero direct CO₂ emissions. Despite the higher total energy demand of the hydrogen route due to its endothermic nature and the positive enthalpy change, the significant reduction in carbon intensity positions hydrogen as a promising pathway for cleaner DRI production. These findings support the transition of the steel industry toward low-carbon technologies, contributing to compliance with future regulatory frameworks and international decarbonization targets.