Effect of Intrinsic Carbon in Hot Briquetted Iron on Melting and Refining Efficiency under Electric Arc Furnace Conditions for Sustainable Steelmaking with Active Use of H2-Reduced Iron

초록

The melting behavior of hot briquetted iron (HBI) is observed using an induction furnace at 1823 K and compared with FactSage thermochemical computing simulation results. Experimental observation reveals CO gas evolution and slag formation due to unreduced FeO and gangue oxides in HBI-mainly SiO2 with minor content of Al2O3, MgO, and CaO-at each reaction step. Equilibrium calculations are performed to evaluate the effects of HBI charge ratio and intrinsic carbon content in HBI on the melting and dephosphorization efficiency under an electric arc furnace (EAF) condition. For the conditions of higher charge ratio of carbon-free HBI, representing a H2-reduction product, a significant slag volume with low dephosphorization ability is predicted to form, primarily due to an increase in FeO and SiO2 contents. Consequently, when using HBI in an EAF process as an alternative iron source substituting for obsolete scrap, a proper design of raw materials such as intrinsic carbon content in HBI, charging ratio of HBI, and addition of lime are proposed to be essential to control the slag volume, maintain slag basicity, and mitigate CO2 emissions for optimal performance and the sustainable steelmaking technology.

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