Damage characteristics of pulverized coal under different gas pressures in coal and gas outbursts

Coal and gas outbursts are complex dynamic phenomena and are highly hazardous. This article established an experimental system to research the damaging effect of gas on particulate coal during coal and gas outbursts, which replicated the outburst scenario by instantaneously releasing different-pressure gas. The results show that the higher the gas pressure is, the larger the new surface area is, and the gas damages the pulverized coal more drastically. The mass ratio of new granular size coal is between 8-27%. The surface area increased significantly (73.0%-245.2%). The mean order of increasing surface area is SC (1.102 m(2))> DC (0.9875 m(2))> SN (0.8999 m(2))> DN (0.8369 m(2)), which indicates that the extent to which gas destroys particulate coal is inversely proportional to the solidity coefficient and positively proportional to the adsorptivity. The ability of weakly adsorbable gases to break particulate coal is more affected by gas pressure. The degree of breakage of low-firmness coals is more responsive to gas pressure. The percentage of coal mass broken by gas is positively correlated with gas pressure and adsorptivity and negatively correlated with the firmness coefficient. Finally, the quick release of gas occurs in three stages: an acceleration section (0-0.05 s), a high-speed section (0.05-0.15 s), and a deceleration section (after 0.15 s).