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

• Detailed numerical comparison of Fe 2 O 3 reduction using CO and H 2 as reducing agents. • Two Direct Reduced Iron models are built based on H 2 and CO reduction. • CO-based reduction process requires significantly less energy compared to the H 2 -based process. This study presents a comparative analysis of Direct Reduced Iron (DRI) production using carbon monoxide (CO) and hydrogen (H 2 ) 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 (Fe 2 O 3 ), 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 Fe 2 O 3 . Based on stoichiometric reactions (Fe 2 O 3 + 3CO → 2Fe + 3CO 2 and Fe 2 O 3 + 3H 2 → 2Fe + 3H 2 O), the simulation estimates the production of approximately 144.2 tons of metallic iron per hour. For the hydrogen-based route, ∼104,200 m 3 /h of H 2 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 CO 2 per ton of Fe, while the H 2 -based route achieves zero direct CO 2 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.