Comparative Analysis of Spontaneous Combustion Hazard Characteristics in Upside and Downside Ventilation Airflow Adopted Mining Areas

To comparatively analyze the distribution characteristics of spontaneous combustion hazard zones in upside and downside ventilation airflow adopted mining areas, field measurements of O₂ and CO concentrations were determined at the two sides of intake and return airways and the middle of the goaf in 1201 working face of DuanWang Mine; characteristic combustion temperatures and spontaneous ignition kinetic parameters of coal samples were obtained by thermogravimetric analysis; distributions of oxygen and temperature fields under different heat source intensities in upside and downside ventilation airflow adopted working faces were compared by CFD simulation. The results show that the critical positions of the inertisation zone in the goaf corresponding to the intake side, return side and middle of the working face were 200 m, 290 m and 175 m away from the working face, respectively; the moisture evaporating temperature of the coal sample was around 170°C, and the ignition point temperature was about 320°C. When the heat flux was 0 W/m², the areas of spontaneous combustion hazard zones (oxygen volume fraction >8%) in upside and downside ventilation airflows adopted goafs were almost the same; as the heat source increased, the distribution of spontaneous combustion hazard zones in the goaf was more significantly affected by the hot wind pressure, the hazardous area in upside ventilation goaf was about 3 times of that in downside ventilation when the heat flux reached 20 W/m². The simulation laws were consistent with the measured results. The comparative analysis concludes that downside ventilation is conducive to preventing and controlling spontaneous combustion of residual coal in this working face.