Abstract
Research and development activities to realize carbon-neutral iron- and steelmaking processes have been underway worldwide. It is considered that the use of hydrogen in steelmaking is a promising method, and various projects to industrialize hydrogen direct-reduction shaft furnaces have been carried out. However, due to the vast scale of the steelmaking industry, abruptly switching iron- and steelmaking processes to hydrogen-based processes is difficult. Therefore, it is essential to design pathways during the transition period. Reducing carbon dioxide emissions from ironmaking processes is indispensable, even on these pathways. For example, the GREINS (GREen INnovation in Steelmaking) project in Japan is taking a multi-track research approach that includes the hydrogen direct-reduction shaft furnace, hydrogen-enriched blast-furnace operation, and so on. It is known that the hydrogen reduction of iron ore proceeds faster than the carbon monoxide reduction and is an endothermic reaction. Therefore, the inner state of the blast furnace will change when hydrogen is used. Even under such conditions, the stable operation of the blast furnace must be achieved. To design and optimize the hydrogen-ironmaking process, the characteristics of hydrogen reduction and the in-furnace state must be quantitatively understood. For this purpose, a novel multi-scale numerical approach for iron ore reduction in a blast furnace under hydrogen-rich conditions was conducted. This approach includes three different scales, namely particle scale, furnace scale, and layer scale. In this presentation, the details of this approach, as well as the current state of Japanese research and development toward carbon-neutral steelmaking, will be introduced.