Towards coal based continuous steelmaking Part 2 – Low carbon to ultralow carbon steel

Abstract

Low carbon steel produced continuously from powdered coal and iron ore fines in a circuit employing three melt circulation loops is subjected to countercurrent contacting with argon in a packed bed at 100 mbar pressure. New generalised correlations are developed for both gas and liquid phase mass transfer in liquid metal irrigated packed beds. Consideration is next given to the likely rate controlling mechanisms. Data reported in the literature are reassessed to demonstrate that liquid phase transfer predominates and interfacial chemical kinetics is unlikely to exert a major influence on the process for producing ultralow carbon (ULC) steel. Although liquid phase diffusion of oxygen is clearly more important, gas phase mass transfer at 100 mbar must still be taken into account. Calculations indicate that 2 000 000 tpa Fe requires a ULC tower with an internal diameter of 2·6 m packed with 6·5 m of 150 mm ceramic balls, for example.