Reducing Blast Furnace Dependence on Coke: A Review of Low-Carbon Strategies

Reducing coke consumption is one of the most effective approaches for lowering CO₂ emissions in blast furnace (BF) ironmaking. Coke plays both chemical and physical roles in the BF, acting as a reductant, providing heat, and supporting the burden to maintain gas permeability. While part of its chemical function can be replaced by alternative carbon-based fuels and reducing agents, its physical load-bearing role remains difficult to substitute. This review summarizes recent studies on the partial replacement of coke in BFs from the perspective of low-carbon ironmaking. Rather than treating different coke-saving technologies as separate methods, this review discusses coke reduction according to the specific functions of coke being replaced. Alternative carbon sources, H₂-rich reductants, CO₂-to-CO recycling, load-bearing packed-bed materials, and burden structure optimization are considered. This perspective helps explain why alternative fuels, H₂-rich gases, and recycled CO can reduce the chemical demand for coke, while deeper coke reduction remains limited by the difficulty of replacing coke's structural role. Overall, meaningful coke reduction is more likely to rely on the combined use of several approaches while maintaining process stability and engineering feasibility. This function-based understanding may help guide the development of more practical lower-carbon BF ironmaking strategies.