Combustion characteristics of the thermal-mechanical coupling of broken coal in multiple atmospheres and the re-ignition laws of residual coal

Since deep mining is susceptible to various problems, such as high ground stress and high ground temperature, coal spontaneous combustion (CSC) disasters are serious. The effects of uniaxial pressure (0, 2, 4, and 6 MPa) on the oxidation and heat release characteristics of coal in a multielement atmosphere are studied. The apparent and re-ignition characteristics of the unloaded residual coal are analyzed. The results show that the intersection temperature first decreases and then increases with increasing axial pressure, and the exothermic strength is the highest under a pressure of 2 MPa. Coal is more easily broken during the oxidation process under CO2 atmosphere, and the fracture layer on the residual coal surface increases with increasing pressure. During the re-ignition process of 2 MP residual coal, the initial heat release temperature is higher and the total heat release is the largest. Under a 6 MPa axial pressure, the functional group content increases in the early stage of secondary oxidation. The hydroxyl groups produced during the initial oxidation stage promote secondary oxidative re-ignition of the residual coal. Coal samples after intense combustion under uniaxial compression in a CO2-containing gas environment are still at risk of secondary oxidative re-ignition.