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

Abstract

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.