A review on production and application of direct reduced iron in gas-based shaft furnace-electric arc furnace route

The iron and steel industry, standing as a quintessential manufacture example with high consumption, pollution and emissions, faces significant environmental and sustainable development challenges. Electric arc furnace (EAF) steelmaking process mainly uses scrap as raw material and is characterized by environmentally friendly and recyclable process. However, the further development of EAF route in China is limited by the reserve, supply, availability and quality of scrap resource. Direct reduced iron (DRI) is one of typical low-carbon and clean charges, which can effectively make up for the adverse effects caused by the lack of scrap. The physical and chemical properties, classifications, and production technologies of DRI are firstly reviewed. In particular, the reducing gas types, reduction temperature, and reduction mechanism of the DRI production with gas-based shaft furnace (SF) technology are detailed. Considering the crucial role played by DRI application in EAF, the influences of DRI addition on EAF smelting rules and operations including the blending and charging process, heat transfer and melting in molten bath, slag formation operation, refractory corrosion, and slag system evolution are then further discussed. Finally, the comparative analysis and assessment of the consumption level of material and energy as well as the cleaner production both covering the clean chemical composition of molten steel and the clean environment impact in EAF steelmaking with DRI charged are conducted. From perspectives of metallurgical process engineering, a suitable route of hydrogen generation and application (from coke oven gas, methanol, and clean energy power), CO2 capture and utilization integrated with SF-EAF process is proposed. In view of the difficulties in large-scale DRI application in EAF, the follow-up work should focus on the investigation of DRI charging and melting, slag system evolution and molten pool reaction rules, as well as the developments of the DRI standardized use technology and intelligent batching and control models.