Cohesive components in coal and their cohesive mechanism during pyrolysis

The cohesive components in coals and their detailed structure were investigated. The results show that the caking index of Linfen fat coal after extracting by benzene and tetrahydrofuran (THF) decreases from 89 to 43. Through analyzes of FT-IR and synchronous fluorescence spectrometry, anthanthrene is considered as the primary cohesive component to determine the cohesiveness of coal, and it is 42.4 wt% in the extract by THF from fat coal. Meanwhile, 1-naphthol, the secondary cohesive component to influence the cohesiveness of coal, is 22.8 wt% in the extract by benzene from fat coal. The cohesive phenomenon of coal has a positive correlation with the maximum aromaticity index (fa), and the cohesive phenomenon cannot be found during pyrolysis when the maximum fa of samples is smaller than 0.640, which are found from SEM images and XRD spectra of the carbonized samples. Moreover, the addition of anthanthrene makes Shenfu sub-bituminous coal produce cohesive phenomenon that coal particles connect together through the formation of a uniform surface. Based on these findings, a possible cohesive mechanism of coal was proposed.