Experimental study on the transporting and crushing effect of gas on coal powder during the develop stage of coal and gas outburst in roadway.

In recent years, coal and gas outburst disasters are still occurring and difficult to prevent, seriously endangering the safety of coal mine production. It is well known that the transporting and crushing of outburst coal is the main pathway of energy dissipation during the coal and gas outburst process. However, a consensus regarding how much gas involves in outburst and affects energy dissipation is still lacking. Quantitative study on the gas effect on migration and fragmentation characteristics of outburst coal in restricted roadway space can improve the energy model and guide the prevention and control of gas outburst. In this paper, an improved visual coal and gas outburst dynamic effect simulation experiment system was used to conduct outburst simulation experiments at different gas pressure conditions. The results showed that the movement of outburst coal in the roadway has experienced various flow patterns. In the initial stage of the outburst, under low gas pressure condition, the motion of the outburst coal was dominated by stratified flow. However, as the gas pressure increases, the initial acceleration increases, and the outburst coal mainly move forward rapidly in the form of plug flow. The average velocity at 0.3, 0.5, and 0.8 MPa gas pressure condition were 6.75, 22.22 and 35.81 m/s, respectively. Gas also has a crushing effect on outburst coal. With increasing gas pressure, the number of coal powder particles of the same mass increased significantly, and the range of the particle size distribution of the particles decreaed, and the median particle size decreased. As the gas pressure increases, the outburst intensity gradually increases, and the total energy involved in the outburst work also increases. However, the energy dissipation pathways are different. At 0.3 MPa, the energy dissipation is dominated by crushing energy, which is about six times the ejection energy. As the gas pressure increased to 0.8 MPa, the proportion of the ejection energy gradually increases to about twice that of the crushing energy. Under the experimental conditions, 2.71-13.43% of the adsorbed gas involves in the outburst (AGIO) through rapid desorption, and the proportion increases with increasing gas pressure. This paper improves the energy model of coal and gas outburst, which is applicable to risk assessment and prevention of outburst disasters.

Data for characterization of the pore wetting process of equal-sized granular coals.

In this paper, all measurement and calculation data and their preparation process are presented in detail, which supplements the information published in this co-submission are related to the article "Characterization of the Pore Wetting Process of Equal-Sized Granular Coals based on LF-NMR" [1]. This includes the preparation and component analysis of samples, surface contact angle measurement, analysis of original T2 spectrum and wetting pore size distribution (W-PSD) conversion calculation process. Hence the reader can use the data for their validations and analysis. LF-NMR experiments were conducted for the granular coal pore wetting characterization at the large-diameter MacroMR12-150H-I imaging and analysis system, of Suzhou Niumai Corporation in Jiangsu Province, China. Combined with contact angle measurement, which used the JY-PHb contact angle test instrument, we analyzed the pore wetting process in porous media and its characterization method.