Correlations Between Carbon Structure and Properties by XRD and Raman Structural Studies During Coke Formation in Various Rank Coals

The structure and properties of coke are of significant importance in the metallurgical industry. Coke samples were prepared from different bituminous coals at varying temperatures using a one-sided heating furnace. The evolution of carbon structure during the coking process was investigated by X-ray diffraction (XRD) and Raman spectroscopy. The correlations between carbon structure parameters and the properties of the coal and coke were investigated during coke formation. The results indicated that with increasing temperature, the values of L_a, L_c, N, <i>n</i>, and f_a were increased, while the d₀₀₂ values decreased. The L_a/L_c ratio was expanded twice more than raw coal due to condensation and cross-linking reactions, indicating compaction of the carbon structure and the formation of larger aromatic units. A negative correlation was observed between L_c and the Coke Reactivity Index (CRI), whereas a positive correlation was found between L_a and Coke Strength after Reaction (CSR), which mean that coke properties improve with increasing L_c. Specifically, when L_c exceeds 2.4 nm, and L_a lies between 5 and 5.5 nm, the coke exhibits higher quality. The quality of coke is strongly affected by the structural evolution of carbon during the coal coking process.