Experimental Study on the Inerting Effect of Premixed Inert Gas of CO2 and N2 in Goaf

As the conventional inert gas, it is used for the prevention and control of coal's spontaneous combustion, mainly N-2 and CO2. However, there is limited research focusing on the inerting effect of composite inert gas. This paper studied the impact of using a premixed inert gas (N-2 accounted for 50%, 60%, 70%, and 80%) instead of CO2 on the inerting effect of nearly horizontal and gently inclined goaf by building a physical similarity simulation experiment platform. The experimental results showed that the inerting effect of premixed inert gas was better than that of CO2. For instance, in a nearly horizontal goaf, the inerting effect of the premixed inert gas was optimal when the N-2 accounted for 70%. The average O-2 concentration in the monitored area decreased from 9.7% with CO2 to 6.4%. In addition, in the gently inclined goaf, the premixed inert gas exhibited an accumulation state similar to CO2, primarily occurring in the lower part region adjacent to the working face. Furthermore, the accumulation state of premixed inert gas was inversely proportional to its inerting effect. This study has important reference significance for applying inert gas fire prevention and extinguishing technology in mines.