Multi-Step Recycling of BF Slag Heat via Biomass for CO2 Mitigation

Iron- and steelmaking processes create slags, valuable by-products. Industrial utilisation of slag as a lower-value secondary mineral source has been established for decades. Slag heat recovery is an ongoing research topic and has the potential to maximise energy efficiency in iron and steel production. Heat recuperation aims to tap the unused thermal recycling potential of molten slags. This short communication expands the concept for the utilisation of recovered heat for producing torrefied biomass and biogas. The torrefaction process is linked with slag heat recovery and via the BASE method with enhanced blast furnace operation. Such a combination reduces CO2 emissions significantly in ironmaking processes. Assuming a coke consumption of 350 kg coke per tonne of hot metal and replacing it with 5% torrefied biomass injected as PC with an additional 100 m3/tHM biogas injection, the BF’s CO2 emission related to the coke can be lowered by 7.9% to 108 kg/tHM. In such a manner, the recovered slag heat can directly contribute to CO2-footprint reduction and improve the circular economy and metallurgical sustainability.