Investigation of pore structure characteristics and adsorption characteristics of coals with different destruction types

The occurrence of coal and gas outbursts is closely linked to the presence of tectonic coal. To study the pore structure characteristics and adsorption characteristics of different destruction types of coal, nondestructive coal, destructive coal, strongly destructive coal, pulverized coal, and fully pulverized coal are selected based on the coal and gas outburst mine identification specifications. The experimental methods used are liquid nitrogen adsorption, mercury intrusion porosimetry and CH4 isothermal adsorption. The results show that the pore volume obtained by the Barrett-Joyner-Halenda method and the specific surface area increase with increasing destruction type. For all tested coal samples, the N-2 adsorption/desorption hysteresis loop is not closed when the relative pressure is low, indicating the existence of ink-bottle pores, an elastic structure of the coal and nitrogen affinity in the coal. With increasing tectonic stress, it becomes more advantageous to produce micropores. The pore volume obtained by the mercury intrusion porosimetry experiment increases with increasing destruction types except for the case of fully pulverized coal. High-pressure mercury causes pore deformation and collapse. When the f value is <0.5, the compression effect of the pores is obvious. The smaller the value of f is, the wider is the pore range affected by the high-pressure mercury. The degree of destruction is positively correlated with the porosity, specific surface area, and Langmuir volume. However, the degree of destruction is negatively correlated with the f value and mercury extrusion efficiency.