Electrode Smelting of Hydrogen-Reduced Hematite–Goethite at Laboratory Scale

Abstract The smelting of hydrogen direct reduced iron (H-DRI) from Australian iron ore in an electric smelting furnace (ESF) presents a potential low-emission pathway for the steel industry. Presently, there are no industrial-scale examples of the DRI-ESF process using medium-grade ores from Australia to make hot metal. There is a process knowledge gap that constrains the future application of the DRI-ESF route in both integrated steelworks and hot metal capable of electric arc furnace operations. Demonstrating the process metallurgy for the DRI-ESF process at laboratory and pilot scales can help mitigate the risk of adopting a change in technology. Laboratory equipment and methods were developed for the study of the DRI-ESF process. Hydrogen-reduced DRI at 80 to 92% metallization has been made using Australian hematite-goethite iron ore (MAC fines) in 5 kg batches in a fluidized bed reactor. A laboratory ESF has been developed using a single-electrode DC arrangement capturing the key features of industrial ESFs. Smelting experiments have been carried out with 2.5 to 5 kg charges of zero carbon H-DRI and simulated DRI made from mixtures of iron powder and iron ore fines, with carburisers added including calcined anthracite, coke breeze, and biochar. Hot metals with composition 2.5–4.5% C and 0.05–1.2% Si have been successfully made in tests conducted with in situ sampling for metal and slag. The impact of key variables including C/Fe mass ratio in feed, O/Fe mass ratio in feed, and power density have been studied, and important metallurgical variables such as silicon, sulfur, and phosphorus partitions to slag measured. Graphical Abstract