Answers (1)
CO2 works by displacing the oxygen in the air thus removing the fuel a fire normally needs in order to be a fire. If I assume the fire is in the coal face then the mine is lost. In a mine there are usually many ways for oxygen to get to the fire and using CO2 is impractical for large fires. Coal fires also simmer, they can retain the heat without having the combustion and suddenly burst back to life with the slightest brush of oxygen.
Also coal dust will cause an explosion in the mine, the fire(s) would be a very secondary concern.
I imagine it can but if the fire has banked (extended into the coal bed) then all you'll do is put out the fire at the face, it'll still be burning deeper inside. Possibly, and at great expense, you could drill feed pipes into the coal bed and pump water in either from the face or from ground level down.
So can water be used ?