A fully electrically driven hydrogen direct reduction process for zero-carbon green steel production

Abstract

As one of the most promising pathways for producing zero-carbon green steel, hydrogen-based shaft furnaces face significant challenges related to the heating, transportation, and injection of high-temperature (950–1050 °C) H₂. A production process that integrates induction heating with low-temperature hydrogen injection into the shaft furnace has been proposed. The feasibility of producing high-quality direct reduced iron (DRI) through hydrogen reduction via induction heating has been validated at the laboratory scale. Utilizing advanced in situ XRD analysis, the reduction pathway of iron oxides (Fe₂O₃ → Fe₃O₄ → FeO → Fe) was clearly delineated, revealing the phase transition processes at each stage. Induction heating performance varies significantly with the reduction degree: Fe₂O₃ initially lacks heating capability, but reduction to Fe₃O₄ enhances magnetic properties, improving efficiency. Further reduction to FeO decreases efficiency, which rises again when metallic Fe becomes the dominant phase. Under induction heating, DRI samples reach over 900 °C within seconds, demonstrating strong heating potential. Integrating electrolytic hydrogen generation with induction heating produces high-quality DRI, achieving a 96.04% reduction in 40 minutes at 750 °C. These findings establish a fully green, electric-driven direct reduction system, eliminating the need for high-temperature reducing gases and advancing sustainable iron production.