Research on Underground CO Sources and Abnormal Exceedance in the Tailgate Corner of Low Metamorphic Coal Seam

To solve the problem of early warning of coal spontaneous combustion (CSC) caused by abnormal continuous CO overrun in the tailgate corner of low metamorphic coal seam, this paper takes 1306 working face of Dananhu No. 1 coal mine in Hami, Xinjiang as an example. Field measurement, experimental research and numerical simulation were used to study the sources of CO in the tailgate corner and its overrun mechanism, and a CO early warning limit calculation method suitable for CSC oxidation of low metamorphic coal seam is proposed. The results show that the ambient temperature oxidation is the most important source during non-production periods. When ambient O2 concentration is ≥7.7%, the coal sample can undergo ambient temperature oxidation to release CO, and the CO production rate has a good quadratic function fitting relationship with the ambient O2 concentration. The average CO production rate of the dissipation zone in the goaf is 3.3 times that of the oxidation zone, and the CO output proportion is 1.1. The CO early warning limit calculated can indicate the phenomenon of CSC oxidation well. The relevant research work is significant for the safety management of CSC in low metamorphic coal seam mining.