Dimethyl Methylphosphonate for the Suppression of Coal Spontaneous Combustion

The inhibitory effect of dimethyl methylphosphonate (DMMP) on coal spontaneous combustion was investigated. The influence of DMMP on the thermal mass loss and thermal properties in the coal oxidation process was analyzed by synchronous thermal analysis. A DMMP inhibitor concentration of 10% provided the best inhibitory effect on coal oxidation. Addition of DMMP increased the coal ignition temperature by approximately 33 degrees C, the burnout temperature by approximately 63 degrees C, and the initial exothermal temperature by approximately 12 degrees C. It also reduced the total heat release of the coal oxidation process by approximately 1200 J/g. Kinetic analysis of raw coal and DMMP-treated coal showed that DMMP exerted physical inhibition by blocking contact between coal and oxygen in the low-temperature oxidation stage. In the high-temperature oxidation stage, the chemical inhibition effect of DMMP was enhanced and the activation energy increased significantly (approximately 54.79 kJ/mol). Gas phase analysis indicated that DMMP could reduce oxygen consumption and CO emission during the coal oxidation process. On the basis of the above results and quantum chemical analysis, a mechanism for DMMP suppression of coal spontaneous combustion was proposed. This study provides reference data for prevention of coal spontaneous combustion and development of new inhibitors.