Characteristics of oxidation and spontaneous combustion of the major mining coal seam in Dajing area of Easter Junggar coalfield

With the application of programmed temperature-rising coal oxidation experimental apparatus, the authors conducted experiments to study the oxidation process of the major mining coal seam of eastern Junggar coalfield with different particle sizes. Some special parameters, such as the critical spontaneous combustion temperature T_c, the initial temperature for producing the CO, the Graham indexes, the change of CO and O₂ with the increase of temperature, and other C_nH_m gases, were analyzed in the present paper. Results show that the initial temperature of CO increases with the reducing of particle sizes. The average initial CO temperature is about 66.37℃, and this phenomenon doesnt represent this sample has more intensity of reaction than that of others. It also shows that the critical temperature increases with the reducing of particle sizes, and the average critical temperature is about 154.73℃. At the stage of T_a-T_CO, the average oxygen-consumption rate is about 0.2454 mL/min·℃^-1, and at the stage of T_CO-T_b, the rate is about 4.0049 mL/min·℃^-1. With the progress of oxidation, the oxygen-consumption rate of 80～100mesh size sample is higher than that of 120～140mesh size and that of 160～180mesh size, which indicates that the 80～100mesh sample has much more reaction activities than that of both 120～140mesh and 160～180mesh sizes. At the range of 70～100℃, Graham index R₃ has much ability to indicate the coal spontaneous combustion than that of R₁and R₂, which can be used to predict the coal spontaneous combustion. From this research, it is probably to choose the CO concentration, the temperature, the O₂ concentration, the Graham index R₃, the C₂H₄, the C₂H₆, and the C₃H₈ to indicate the coal spontaneous combustion in coal mine.