Influence of Biomass Blending on Metallurgical Performance and Microstructure of Coke

Abstract

A comprehensive investigation on the impact mechanisms of biomass blending on coke microstructure and properties was conducted through multi-scale characterization approaches, including X-ray diffraction (XRD), Raman spectroscopy, nitrogen adsorption porosimetry, and scanning electron microscopy (SEM). The results indicate that the introduction of biomass significantly reduces the graphitization degree of coke, as evidenced by the decrease in crystallite size, the increase in interlayer spacing (d₀₀₂), and the reduction in aromaticity. Raman spectroscopy analysis further confirms that, with the increase in biomass addition, the I_D/I_G value decreases by 0.15–0.25, indicating a reduction in aromatic hydrocarbons with more than 6 fused rings. Meanwhile, the I_D/(I_GR + I_VL + I_VR) value decreases by 0.3–0.5, suggesting an increase of 15–25% in the proportion of small aromatic systems with 3–5 rings. The impact of different biomasses varies significantly: Poplar leaves, due to their high volatile matter content, exhibit the strongest inhibition of thermal polycondensation. In contrast, bamboo maintains a more ordered structure owing to the supporting effect of its silicon-aluminum framework. Pore analysis indicates that the specific surface area of biomass char increased from 1.5956 m² g^–1 without the addition of biomass to 2.0462–2.5356 m² g^–1 with the addition of 8% biomass, while the average pore diameter expanded from 4.1459 to 7.4969–9.5383 nm. SEM observations indicate that poplar leaf coke exhibits the highest porosity but also the greatest structural disorder. In contrast, bamboo coke demonstrates the best mesopore connectivity. This study provides theoretical support for optimizing the performance of metallurgical coke through biomass modification.