Coke Production from Coal and Biomass Blends

The production of metallurgical coke through the coking of coal blends has long been central to ironmaking, supplying the essential combustible material and reducing agent in blast furnaces. Coal and biomass blends—replacing a fraction of fossil coal with organic feedstocks such as wood residues, agricultural by-products or torrefied biomass—offer a route to lower carbon intensity without radical changes to existing cokemaking infrastructure. Biomass inclusion influences the plasticity, thermoplastic range and swelling characteristics of the charge, and must be carefully balanced against the coking coal’s rank and volatile matter to maintain coke strength and porosity. Optimising blend ratios and pretreatment methods (for example, pelletising, torrefaction or pyrolysis) can mitigate adverse effects on coke reactivity and mechanical integrity, while harnessing renewable carbon to reduce net CO₂ emissions. Advances in understanding the interactions between coal macerals and lignocellulosic components, as well as developments in semi-industrial coking ovens and stamp-charging technologies, are extending the feasible biomass addition rates to typically 5–15 wt %. These innovations have global significance: they enable steel producers to adapt to tightening greenhouse gas regulations, valorise regional biomass waste streams and maintain high coke quality standards across diverse coal supplies.

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Coke Production from Coal and Biomass Blends publication trend

The graph below shows the total number of articles in coke production from coal and biomass blends across all publications each year (not limited to Nature Index journals).

Technical terms

Biocoke: Coke produced by coking blends containing a proportion of biomass-derived carbon alongside coal.

Coking blend: A carefully formulated mixture of coals (and optional additives) designed to yield coke with specific structural and reactive properties.

Plasticity (thermoplastic properties): The softening and resolidification behaviour of coal during heating, determining coke morphology and strength.

Coke Reactivity Index (CRI): A measure of coke’s susceptibility to reaction with CO₂ under standard conditions, reflecting its reactivity in the furnace.

Coke Strength after Reaction (CSR): The residual compressive strength of coke following reaction with CO₂, indicating its ability to support burden in a blast furnace.

Torrefaction: A mild pyrolysis process (200–300 °C) applied to biomass to improve fuel properties and compatibility with coal.

References

1. Advances in low carbon cokemaking – Influence of alternative raw materials and coal properties on coke quality. Journal of Analytical and Applied Pyrolysis (2023).
2. Metallurgical Coke Production with Biomass Additives: Study of Biocoke Properties for Blast Furnace and Submerged Arc Furnace Purposes. Materials (2022).
3. Types and Composition of Biomass in Biocoke Synthesis with the Coal Blending Method. Energies (2021).
4. Stamp-Charged Coke-Making Technology—The Effect of Charge Density and the Addition of Semi-Soft Coals on the Structural, Textural and Quality Parameters of Coke. Energies (2021).