Study on the optimization simulation and application of technical parameters of CO₂ injection for fire prevention in goaf in 8059 working face of Yaoqiao Coal Mine

In order to solve the problem of spontaneous combustion of residual coal in goaf in 8059 working face of Yaoqiao Coal Mine, a geometric model of the goaf seepage field was established.By means of numerical simulation, the distribution of O₂ volume fraction in goaf was studied under different injection positions and injection flows of CO₂.The results show that when CO₂ is not injected, the maximum oxidation zone width in goaf is about 60 m; after CO₂ injection, the maximum oxidation zone width is reduced to about 20 m, the oxidation zone width decreases with the increase of CO₂ injection, the O₂ volume fraction in goaf decreases significantly, especially in the air inlet side; the best CO₂ injection port is located at one side of the air inlet roadway about 40 m away from the working face, when the injection volume is 540 m³/h to 720 m³/h, it is relatively suitable. Through the on-site pressure injection of CO₂ in goaf for fire prevention, the hidden danger of spontaneous combustion in goaf is effectively eliminated, and the safe production of the working face is guaranteed.