Effect of Thermal Treatment Temperature on Stacking Structure and Carbon Aromaticity in Coal

Abstract

To understand the properties of coking coal and coke during carbonization process, changes in stacking structure of carbon and carbon aromaticity were estimated using the XRD and NMR measurement techniques for the different four kinds of coking coals thermally treated at various temperatures. In the XRD measurement, the comparison of the diffraction patterns of the coal samples with and without decalcification indicated the proposed method could successfully eliminate peaks from ash components in the diffraction patterns. After thermal treatment, the average number of stacking layers in all the samples increased around temperature of 400-500 °C and slightly decreased around 500-700 °C. In addition, the average number of stacking layers of each sample tended to be larger for sample with higher carbon content. In the 13 C-NMR measurement, the carbon aromaticity became larger for higher thermal treatment temperature, and the order of the carbon aromaticity almost corresponded with that of coke contraction ratio.

Numerical Investigation of the Effect of Inert Components on the Shrinkage Phenomenon of Coke

“…Some studies on the shrinkage behavior of coal during carbonization have been carried out, and it was shown that the properties of coal significantly affected the shrinkage ratio of coke. [6][7][8][9][10][11] One of the important properties of coal that determines the shrinkage ratio of coke is the amount of volatile matter (VM). This is because a larger amount of VM released from the coke decreases the more weight of coke, and it was reported that coal with a larger amount of VM contracted more.…”

“…This is because a larger amount of VM released from the coke decreases the more weight of coke, and it was reported that coal with a larger amount of VM contracted more. 8,9) Regarding another coal property that affects the shrinkage of coke, Iwamoto et al 11) focused on the crystal and chemical structure of coals and reported that coke with higher carbon aromaticity at high temperature showed a higher shrinkage ratio. Alvarez et al 10) reported that the softening properties of coal affect the shrinkage ratio of coke, and that coals with a wide range of softening temperatures and lower viscosities had a higher shrinkage ratio of coke.…”