Problems of cooling sealed fire areas in underground coal mines

Abstract

In current mining practice, the most often used methods of cooling spatially sealed fire areas are: natural cooling, cooling by nitrogen, cooling by water and inert foam and cooling by combustion product recirculation. The technology of cooling with nitrogen represents two variants - the use of liquid nitrogen or nitrogen gas in the area of closed mine workings. From a technical and safety points of view the application of liquid nitrogen is today considered unsatisfactory, while the use of nitrogen gas seams to be highly safe technology for cooling explosion-proof sealed fire areas. Another possibility for cooling fire areas in deep coal mines is so-called natural cooling, where economical costs are indeed zero, but comparing to cooling processes induced by the application of cooling technologies a longer time period necessary for the natural refrigeration of fire areas causes financial losses.