N2 Inhibition Characteristics of Coal Spontaneous Combustion in Goaf: Experimental Study and Numerical Analysis

To investigate the inhibition characteristics of coal spontaneous combustion in goaf under different nitrogen injection conditions, the oxidation and the heat release characteristics of coal bodies with easy spontaneous combustion were characterized by using adiabatic oxidation experiment. A comparative study on the evolution of the coal spontaneous combustion risk zone (CSCZ) in goaf was carried out by using numerical simulation. The results indicate that the oxygen consumption rate of coal bodies with the rise of temperature in a power function. The exothermic characteristics of coal decrease with the increase of N-2 addition. The location and rate of N-2 injection restrict the expansion process of CSCZ, which makes the maximum width of CSCZ shrink, the oxygen attenuation rate, N-2 diffusion intensity and inerting area increase. When the N-2 injection position is 40 m away from the working face and the N-2 injection rate is 450 m(3)/min, the critical ideal value of inhibition coal spontaneous combustion can be achieved.