Fine coal covering for preventing spontaneous combustion of coal pile

In order to investigate the effect of fine coal covering around the bottom of coal stockpile on spontaneous combustion prevention, a two-dimensional math model was established to numerically simulate the fine coal covering coal pile and a coal pile temperature-rising experimental system was setup to study the two-dimensional heat and mass transfer characteristics of air diffusion in the horizontal direction and air heat convection in the vertical direction inside coal stockpiles covered by different thicknesses of fine coal. The results showed that (1) the fine coal located at the bottom of the coal pile can effectively inhibit air convection and diffusion, cut off oxygen replenishment, and prevent the temperature rise inside coal pile, and (2) thicker fine coal has more obvious effect. Finally, the field experiments on the fine coal covering coal piles for preventing self-ignition of coal pile were carried out successfully. The results showed that the uncovered or exposed coal piles self-ignited rapidly within a very short period (18 days), while the coal pile covered with 1 m fine coal lasted for 123 days with a maximum coal temperature of only 59.9 °C. The characteristics of temperature distribution and diffusion inside coal stockpile were studied, and the high-temperature region was found in the region 1.3 m high and 2–3 m deep in the coal pile. The effects of environment temperature and precipitation on self-ignition of coal pile were also analyzed in field experiment. The experimental results proved that the fine coal covering technology can effectively prevent the spontaneous combustion of coal stockpiles. Copyright Springer Science+Business Media Dordrecht 2014