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Water and pyrite (FeS2) in coal have great synergistic effect on coal self-ignite. In order to explore the characteristics of spontaneous combustion of high humidity and high sulfur coal, this paper selected different concentrations of water and pyrite to carry out thermogravimetric experiment and oxidation reaction kinetics analysis. The changes of coal samples oxidation under low temperature in mass and characteristic temperatures were studied through thermogravimetric (TG) analysis. The results indicate that the promoting effect of water on coal spontaneous combustion turns to restrain when it reaches 15%, and water and pyrite have substantial synergistic effect on coal oxygen absorption and mass gain stage (T3–T5 in TG temperatures), besides there is a range of water/pyrite contents (10–15 mass% water and 2–4 mass% pyrite) that have the largest effect on coal oxidation reactions. Through the analysis of oxidation reaction kinetics, it was found that the change rule of the apparent activation energy (Ea) in coal oxygen absorption and mass gain stage is similar to that of the thermogravimetric change, and it was the lowest at 2–4 mass% pyrite and 10–15 mass% water content. The reaction process of coal oxidation by water and pyrite conforms to the equation n = 4 Avrami-Erofeev, therefore water and pyrite just can promote coal oxidation externally. This research provides support for further understanding and control the influence of water and associated pyrite on coal self-ignite. [ABSTRACT FROM AUTHOR]

The chemical structure and morphological of lignite treated with four imidazole ionic liquids (ILs), namely [BMIM][BF 4 , [BMIM][NO 3 , [BMIM][I], and [EMIM][BF 4 , was characterized through scanning electron microscopy and X-ray diffraction. Furthermore, the exothermic properties of the oxidation process at low temperatures (<200.0 °C) were investigated using a C80 microcalorimeter. The results revealed that the IL partially dissolved minerals and side chains of surface molecules in lignite, resulting in reduction of the unit stacking degree, ductility, and number of effective piles, which ultimately led to a lower coalification degree of the treated coal sample. The initial exothermic temperature of the treated coal sample increased and that more thermal energy was absorbed and less thermal energy was released in the endothermic and exothermic phases, respectively, as a result of the destruction of the molecular structure of coal by IL. The exotherm and the exothermic heat release rates from treated coal samples were consistent and in the following order: IL-untc > [BMIM][NO 3 -tc > [BMIM][I]-tc > [EMIM][BF 4 -tc > [BMIM][BF 4 -tc. The IL destroys the chemical structure of the coal, resulting in a decrease in the activity of the coal, which is manifested by an increase in apparent activation energy. • A new initial temperature characterization method was established. • The external morphology and structure of coal have changed due to ILs. • ILs have a prominent effect of reducing on the exothermic properties. • The oxidation activity of coal could be feasibly inert by ILs. [ABSTRACT FROM AUTHOR]

• Pyrolytic behavior differs significantly with different degrees of thermal aging. • Thermal aging leads to more easily pyrolysis of cables. • Different degrees of thermal aging have little effect on the pyrolysis mechanism. • The most dangerous threshold for the pyrolysis of ZR-BVR is aging for 20 days. Thermal aging produces irreversible aging to home decoration PVC insulation copper cables through high temperatures, and their pyrolytic behavior changes as a result. The thermogravimetric-Fourier transform infrared analysis, the model-free method and the Málek method were used to investigate the effect of thermal aging on the pyrolysis mechanism of domestic PVC insulation copper cables. It was found that pyrolysis is more easily to occur in aged cables, and 20 days of aging is the most dangerous threshold for the pyrolysis of ZR-BVR cable insulation. The pyrolysis release gases were mainly concentrated in the temperature intervals of 270-340 and 400-700°C. In addition, it should be noted that different degrees of thermal aging affect the pyrolysis behavior of cable insulation but have little effect on the pyrolysis mechanism. [ABSTRACT FROM AUTHOR]

Abstract This study examined the combustion characteristics and kinetics of coal samples treated with imidazole-based ionic liquids (ILs), namely, [Emim][BF 4 ], [Bmim][BF 4 ], [Bmim][NO 3 ], and [Bmim][I], under oxidation. The oxidation of the coal samples was investigated using thermogravimetry (TG) at heating rates of 4.0, 6.0, 8.0, and 10.0 °C·min−1. The results for the IL-treated samples revealed that the composite index S (representing the ignition, combustion, and burnout properties) decreased and H f (representing the rate and intensity of the combustion process) increased with high correlation coefficients. The characteristic temperatures of the maximum oxidization mass gain (T 2), ignition point (T 3), maximum mass loss rate (T 4), and burnout point (T 5) increased by 13.1 ± 0.5, 9.2 ± 0.5, 21.5 ± 0.5, and 35.9 ± 0.5 °C, respectively. At T 3 and the maximum mass loss rate, the release of CO and CO 2 was further altered, suggesting that the C O functional groups were damaged or oxidized. The results of the Ozawa-Flynn-Wall kinetic equation used to determine the apparent activation energy (E a) of coal samples revealed that the E a of the treated samples increased. The reaction rate constant characterizes the effect of E a and pre-exponential factors (A), and the results showed that ILs can weaken the reaction process at low temperatures (<130 °C). Highlights • Changes in the combustion performance occurred in samples treated with ILs. • The S decreased and H f increased with an increase in the amount of ash. • The reaction process of the treated sample is accelerated above 130 °C determined by k. • The difference in gas reveals that C O was destroyed by ILs. [ABSTRACT FROM AUTHOR]