Effect of Coal Particle Size on Pore Structure Characteristic and Gas Adsorption Characteristic

In order to study the pore structure characteristics and gas adsorption characteristics of coal briquettes as well as their correlations under different particle sizes, the middle rank coal samples of Xinjiang Mine were selected to prepare coal briquette samples of four sizes. The samples were tested by NMR and high pressure gas isothermal adsorption capacity, to determine the T₂ spectrum and gas adsorption isotherm of different particle sizes. The results show that the T₂ spectrum signals of different particle sizes show two peaks of micropores and mesopores, the relaxation time is mainly concentrated from 1.0 ms to 100.0 ms; the peak area of medium and large pores is negatively correlated with the particle size, the peak area of micropores is positively correlated with the particle size; under the same adsorption conditions, the smaller the average particle size of briquette is, the larger the total amount of adsorbed gas is, and the gas adsorption constants a and b and the gas adsorption saturation X are negatively correlated with the particle size; as the peak area of micropores increases, the adsorption rate of gas increases, and the gas adsorption capacity increases within a certain range, then tends to be gentle after reaching a certain value.