Experimental and Kinetic Study of Melting Hydrogen-Direct Reduced Iron (H-DRI) and Commercial DRI Pellets in EAF Slag
Aliyeh Rafiei (ArcelorMittal)
Neslihan Dogan (TU Delft - Mechanical Engineering)
Stanley Sun (ArcelorMittal)
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Abstract
In this study, the kinetics of melting hydrogen-direct reduced iron (H-DRI) and commercial-direct reduced iron (C-DRI) reduced by natural gas, in EAF slags containing 20 to 30 pct FeO at 1873 K, were investigated. The melting behavior of DRI pellets in the slag was visualized using X-ray fluoroscopy. There were fundamental differences between H-DRI and C-DRI melting and reacting with slag. (1) Considerable CO gas was generated during the melting of C-DRI due to the reaction of C and FeO, while there was no gas evolution from H-DRI melting due to the absence of carbon. (2) The stirring effect caused by the CO bubbles during C-DRI melting significantly improved the heat transfer by convection, and it accelerated melting and reaction kinetics; therefore, the rate of C-DRI melting was much faster than that of H-DRI. (3) The generated CO resulted in slag foaming, i.e., intensive slag foaming was observed during the melting of C-DRI pellets, whereas no slag foaming was observed during the melting of H-DRI pellets. (4) Slag’s FeO content impacted the rate of DRI melting; increasing slag’s FeO content from 20 to 30 wt pct, which shortened the melting duration of H-DRI pellets from 148 seconds to 120 seconds. The investigation demonstrated the key role of C content in DRI during DRI melting and future EAF operation with H-DRI.