Abstract
The iron and steel industry accounts for nearly 7% of global CO₂ emissions, prompting growing interest in sustainable ironmaking technologies aimed at reducing greenhouse-gas emissions. Hydrogen-based reduction has emerged as a promising alternative to conventional carbon-based processes, as it produces water vapor instead of CO₂. However, for efficient electric arc furnace (EAF) operation, the reduced iron must contain a controlled amount of carbon to promote slag foaming, improve arc stability, and lower the melting temperature of iron. In this study, hydrogen reduction and carburization of iron ore pellets was carried out in a thermogravimetric furnace under a fixed hydrogen flow rate at various temperatures, followed by carburization using 10% CH₄ and 90% H2. Phase evolution, microstructural features, carbon content, and chemical composition were analyzed using XRD, SEM–EDS, LECO carbon analysis, and XRF, respectively. The results indicate that complete reduction corresponds to approximately 14% mass loss during hydrogen reduction. The reduction rate increased significantly with temperature, demonstrating the strong temperature dependence of hydrogen-reduction kinetics. During the carburization stage, cementite (Fe₃C) formation was more pronounced at 900 °C, whereas lower carburization levels were observed at 700 °C, confirming the temperature dependence of carbon uptake. Carbon in the reduced pellets was present in two forms: graphite and cementite. The combined hydrogen reduction and controlled carburization approach demonstrates a viable pathway toward low-carbon and green steel production.