Causes of Spontaneous Combustion of Coal and Its Prevention Technology in The Tunnel Fall of Ground of Extra-thick Coal Seam

On the basis of the four factors of spontaneous combustion of coal, the causes of such combustion in the tunnel fall of ground were comprehensively analyzed. The causes include the generation of float coal, influence of hot wind pressure on the laneway, and airflow dynamic pressure caused by sloping roadways. According to the characteristics of a fire that occurred in the intake airflow roadway of working face 12190 in the Geng Cun Coal Mine, a three-phase foam composed of mud, nitrogen, and water was used to extinguish the fire. The foam was injected into the fire zone through boreholes on the tunnel roof. Given the precise scheme and reliability of the technology, the fire was successfully extinguished. The specific technological process and parameters of the technology are discussed in detail. It is concluded that the three-phase foam is useful in preventing spontaneous combustion of coal in the tunnel fall of ground. It serves as a new method for preventing such phenomenon in extra-thick coal seam.