2026 Park H2 DRI Offgas Carburization Melting

Hydrogen-based ironmaking is one of the promising strategies for achieving a carbon-neutral ironmaking process. However, Hydrogen-Direct Reduced Iron (H2-DRI) contains almost no carbon, resulting in higher energy consumption during the smelting process. The present study investigates the feasibility of using industrial off-gas as carburizing agents for H2-DRI through CALPHAD thermodynamic calculations and laboratory-scale experiments. The carburizing potential, evaluated in terms of the extent of Fe3C formation, revealed that CO and CH4 were effective in carburization at low and high temperatures, respectively. Among the off-gases, COG–LDG mixtures exhibited higher carburizing potentials for H2-DRI than COG–BFG due to their lower CO2 content. High-temperature carburization was found to be less favorable as it hindered Fe3C formation while promoting free carbon deposition. The study defined a Carburization Ratio and Carbon Utilization Ratio to assess carburization effectiveness. Additionally, the melting behavior observed indicated that sole carburization was insufficient for complete melting; thus, simultaneous consideration of fluxing and carburization is necessary. These findings advance fundamental understanding of gaseous carburization and its implications for optimizing H2-DRI melting in the smelting process.