Abstract: To investigate the flow rules of carbon dioxide during the process of infusing carbon dioxide into the goaf, three-dimensional geometric model of goaf were established, and through numerical simulation, the flow characteristics of carbon dioxide in the goaf were further studied. The results show that the air leakage in the working face can be reduced by infusing inert gas into goaf, and the carbon dioxide can reduce more air leakage into goaf than that of nitrogen when the same amount of carbon or nitrogen has been infused into goaf. Meanwhile, the carbon dioxide infusion can lower the oxygen volume fraction in the entire goaf, while oxygen volume fraction in the goaf lowers strikingly only when nitrogen is infused into the goaf for deep distance. Thus, infusing carbon dioxide into goaf can reduce the air leakage into goaf, and lower oxygen volume fraction in goaf more effectively, that is, infusing carbon dioxide into goaf can produce much better effects of fire prevention than that of nitrogen.

Key words: goaf, fire prevention, carbon dioxide, nitrogen, numerical simulation