There is a positive feedback mechanism of desorption,
pulverization,
and redesorption in the process of coal and gas outburst. The coal
pore structure changes to some extent in the process of coal pulverization
and has a related impact on the dynamic parameters of coal particle
gas desorption. To understand the impact of desorption damage on the
dynamic characteristics of coal particle gas desorption, in this paper,
a self-developed coal particle gas desorption test device is used
to measure the amount of methane desorption of different coal samples
repeatedly desorbed under the same adsorption equilibrium pressure.
The results show that the methane desorption kinetic curves of the
four coal samples based on desorption damage basically have the same
trend. Nie’s diffusion model can better describe the methane
desorption characteristics of coal particles. After desorption, the
methane desorption amount, initial desorption velocity, diffusion
ability, and ultimate amount of methane desorption of the coal samples
are greater than those before desorption. The desorption damage affects
the relevant dynamic parameters of the coal particle gas diffusion
model, and its impact on the outburst coal is greater than that on
raw coal. In addition, the pore size distribution and change characteristics
of the coal samples before and after desorption are analyzed quantitatively
via a low-temperature liquid nitrogen adsorption test and fractal
dimension-related theory. It was found that the pore volume peak area
of the coal samples affected by desorption damage within each pore
size range was significantly larger than that before desorption. Among
them, micropores have the most significant impact on the desorption
damage of coal samples, and the peak area of the pore volume of protruding
coal is greater than that of raw coal, indicating that the internal
pores of coal after desorption damage are more developed than those
of raw coal.