Experimental study on kinetic parameters and oxidation reaction stage of coal spontaneous combustion

The phenomenon of coal spontaneous combustion will cause fire and posing a great threat to the safety production of coal mine. In order to further understand the characteristics of different oxidation stages in the process of coal spontaneous combustion, temperature-programmed experiments of coal samples under three different oxygen concentrations (11%, 16%, 21%) are carried out. The variation rules of important parameters characterizing coal spontaneous combustion, such as crossing point temperature, CO concentration, oxygen consumption rate, heat release intensity and apparent activation energy are analyzed. Three key characteristic temperature points in the process of oxidation are determined, and four oxidation stages in the process of coal spontaneous combustion are divided according to them. The apparent activation energy of each oxidation stage is calculated, and the comparison is made with the previous historical data. The results show that under the condition of sufficient oxygen concentration, the crossing point temperature calculated by experiment is 143.5 ℃, and the error with the theoretical value calculated by empirical formula is only 6.41%. The CO concentration, oxygen consumption rate and heat exothermic intensity increase with the increase of oxygen concentration, and the oxygen consumption rate and heat exothermic intensity conform to the linear expression. The three characteristic temperature points of the coal sample are 80.4 ℃, 125.9 ℃ and 191.8 ℃, respectively. The research results of this paper and historical data show that the apparent activation energy increases first and then decreases with the process of spontaneous combustion reaction. The apparent activation energy value of stage III deep oxidation reaction reaches the maximum, reaching 52.06 kJ/mol. The research contents hope to provide some basic reference for the characteristics and prevention of coal spontaneous combustion.