Effect of Desorption Damage on the Kinetic Characteristics of Coal Particle Gas Desorption

Abstract

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.

Characterization of Coal Particle Methane Desorption and Optimization of Desorption Model Based on Desorption Damage

“…Based on the methane diffusion coefficient at t 0 , it is found that the desorption times of four samples have a linear relationship with the diffusion coefficient (Figure ). The effect trend of desorption times on the diffusion coefficient may be due to the fact that some micropores in the coal body are opened due to damage and destruction after desorption, resulting in variations in the pores and diffusion routes of micropores and an increase in the diffusion coefficient. , In order to verify the above judgment, pore analysis of coal samples was carried out by a low-temperature liquid nitrogen adsorption experiment. Figure indicates a significant increase in pore volume peak area in coal samples after desorption, indicating the opening of micropores and pore channels during the desorption process, resulting in larger pore volume and adsorption capacity.…”

Study on coal pulverization characteristics and gas desorption mechanism based on impact crushing experiment

“…The determination of diffusion coefficient is generally based on Fick 's diffusion law. Through the change curve of methane desorption amount and desorption time, ln(1- Q t / Q ∞ ) is linearly fitted with t , and then the diffusion coefficient is obtained [ 8 , 27 , 50 ].…”

“…The course of coal and gas outburst is also a procedure of rapid release of gas internal doublerun drill energy and coal crushing and throwing. The continuous crushing of coal body below the function of elastic potential energy accumulated in coal rock is a essential requirement for the occurrence and development of outburst [ [6] , [7] , [8] ]. Therefore, in-depth study of coal crushing related content is very important for understanding the mechanism of outburst, and it may similarly bring guiding value to assessment and prevention of coal mine disasters.…”

Analysis and Prevention of Rock Burst Risk of Working Face under the Influence of Continuous Irregular Triangular Coal Pillar Stress Concentration Area

“…More than 95% of the raw coal is mined via underground mining methods. , The production mode of underground operations is very different from that of surface mining. There are many technical problems in underground mining, and many coal mine production accidents will be faced at the same time. − Rock burst is a dynamic phenomenon in which the elastic potential energy of the surrounding coal and rock mass is suddenly and violently released under certain conditions during coal mining production, resulting in severe vibration and severe damage to the coal and rock mass, making this phenomenon very destructive. − …”