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The determination of the influence law of coal molecular active structure on its oxidation and exothermic characterization parameters is one of the keys to effectively prevent coal spontaneous combustion, but it is difficult to quantify the influence of specific group structure on coal spontaneous combustion, and solvent extraction technology can peel the structure of coal molecular active group to explore effective coal spontaneous combustion reduction technology. In this paper, the coal sample from Caojiatan Coal Mine was treated by solvent extraction technology. The extracted coal sample was tested by STA 8000-Spectrum thermal analysis instrument, and the influence of coal sample extraction on the characterization parameters of oxidation thermal physical properties was studied. The results show that the thermal physical properties of the raffinate coal sample are different from the original coal group. The mass of the raffinate coal sample decreases in the mass gain stage on the TG curve, the mass loss rate decreases in the combustion stage on the DTG curve, and the absolute area of heat release decreases on the DSC curve. The extraction reagent mainly reduces the coal mass entering the combustion stage by weakening the early reactivity of coal, and then inhibits the thermal release power of coal spontaneous combustion reaction to prevent the effect of coal spontaneous combustion. This study will provide a new idea for the development and innovation of coal spontaneous combustion active prevention and control technology. [ABSTRACT FROM AUTHOR]

The functional group structures of coal molecules are one of the most important factors affecting spontaneous combustion. However, it is difficult to determine the exact effects of such structures. Extraction technology is able to modify the functional groups in coal as a means of inhibiting spontaneous combustion reactions. The present work extracted coal from the Caojiatan mine in northern Shaanxi, China, with various solvents. The extraction effectiveness of these solvents was found to decrease in the order of dioctyl sulfosuccinate (AOT) > water > n-hexane > cyclohexane + AOT + ethanol > cyclohexane > ethanol > methanol. With the exception of the AOT, the concentration of functional groups in the extracted coal was decreased compared with that in a control specimen extracted using only water. Ethanol, n-hexane, and methanol provided the optimal extraction efficiencies in terms of capturing coal molecules with aromatic structures, aliphatic structures, and oxygen-containing groups, respectively. The results of this work are expected to assist in future research concerning the extraction of coal molecules with specific functional groups. This work also suggests new approaches to the active prevention and control of spontaneous combustion during the mining, storage, and transportation of coal. [ABSTRACT FROM AUTHOR]

Coal spontaneous combustion (CSC) is one of the main disasters that plague coal mine safety production. It is of great significance to clarify the relationship between coal oxidation reaction rate and oxygen concentration for the prevention and control of CSC disasters. In the present study, an improved model of coal oxidation reaction order is established based on previous studies. Taking long flame coal as an example, the nonlinear relationship between coal oxidation reaction rate and oxygen concentration is obtained. In addition, the variation of oxidation kinetic parameters was studied, and the actual oxygen consumption rate of coal oxidation was calculated. The results show that oxidation reaction order of the experimental coal samples was generally <1, and a stage linear change with temperature (clear mutations occurred at 60, 90, and 160 °C), indicating a nonlinear relationship between oxidation reaction rate and oxygen concentration. The calculation results of two coal oxygen consumption rate models were compared. Under the first-order assumption, the error rate of the calculation results can reach 50.86%, and the slight change of reaction order has a great influence on the reaction rate. The results can provide a theoretical basis for accurate analysis of coal–oxygen composite reaction rates. [Display omitted] • Improved mathematical model of coal oxidation reaction order was established. • Nonlinear correlation between oxidation rate and oxygen concentration was clarified. • Change in oxygen consumption rate with temperature was accurately calculated. [ABSTRACT FROM AUTHOR]