Extinguish the fire can be by an inert gas CO2. It is much heavier than air. so CO2 can displace oxygen and CO, H2, CH4. If dry ice (cold solid CO2) is placed at the bottom of mine CO2 will evaporate and displace-up reactive gases It should be kept at a SAFE DISTANCE from the toxic gases and flames rising from the groundWhen the mine is completely filled with CO2 fire goes out. Perform work in the mine after that, it will be possible only with the breathing apparatus with compressed air.