Low-temperature exothermic oxidation characteristics and spontaneous combustion risk of pulverised coal

Abstract

To investigate the spontaneous combustion risk of pulverised coal, the low-temperature oxidation heat flow of three metamorphic pulverised coals was measured using a C80 microcalorimeter system at various oxygen concentrations to investigate the spontaneous combustion risk of pulverised coal. The results indicated that low-temperature exothermic oxidation of pulverised coal occurred in stages that had distinct characteristics. When the temperature increased, the heat flow curve of RNM and QM pulverised coals first decreased, then increased, and finally decreased, but the heat flow curve of the PSM pulverised coal first decreased and then increased. A considerable lag was observed in the heat flow curves with the decrease in the oxygen concentration, and the characteristic temperature increased. Stage 1 released the least heat, whereas stage 3 released the most heat. A decrease in the oxygen concentration considerably reduced the heat release of pulverised coal. A spontaneous combustion risk index was proposed on the basis of low-temperature oxidation heat release of pulverised coal. Decreased oxygen concentration and high metamorphism of pulverised coal considerably reduced the spontaneous combustion risk index.