Coating of Biocarbon to Reduce Reactivity for Slag Foaming Applications in Electric Arc Furnace Steelmaking

As the steel industry transitions toward net-zero greenhouse gas emissions, biocarbon emerges as a promising renewable alternative to replace fossil carbon for slag foaming in electric arc furnace (EAF) steelmaking. However, the high porosity and reactivity of biocarbon leads to technical challenges associated with injection of biocarbon and foam stability, which reduces process energy efficiency. This study investigates a novel approach to address the technical challenges by enhancing biocarbon performance in slag foaming. The enhancement is achieved by coating solid biocarbon particles with bio-oil followed by heat treatment to reduce particle porosity and reactivity. Petcoke, uncoated biocarbon, and bio-oil-coated biocarbon were systematically characterized to evaluate their physicochemical properties, reactivity profiles, and interaction with synthetic slag. Particle morphology analysis revealed that coating reduced biocarbon porosity and increased biocarbon surface roughness. Thermogravimetric analysis (TGA) experiments confirmed that coating moderated biocarbon reactivity with air and CO₂, and slag. Interaction tests with slag revealed that coated biocarbon exhibited intermediate behavior, although still more reactive than petcoke but much less reactive than uncoated biocarbon, facilitating more stable and prolonged slag foaming. Coated biocarbon can possibly generate sustained foamy slag with improved duration compared to uncoated biocarbon, while still achieving comparable foaming height. These findings highlight the potential of coated biocarbon to overcome the technical barrier of biocarbon utilization and serve as a feasible, low carbon-intensive injection material for EAF steelmaking process.