Correlation between oxygen concentration and reaction rate of low-temperature coal oxidation: A case study of long-flame coal

Self Cite

Coal gangue spontaneous combustion has caused serious environmental and ecological problems. To investigate the reaction kinetic parameters of the gangue and the exothermic characteristics of the spontaneous combustion of the influence of the law, this study employs the thermogravimetric method to explore the characteristic parameters of the pyrolysis and oxidative combustion process of the gangue from the perspective of thermodynamics, and, at the same time, using the differential scanning calorimetry (DSC) on the exothermic effect of the gangue to explore the gangue to obtain the gangue and the original coal TG/DTG/DSC curves to be compared and from the perspective of thermodynamics. The change rule and potential parameters in the pyrolysis and oxidative combustion process of coal gangue (CG) were analyzed, the oxidation kinetic properties of CG were studied, and the reaction mechanism of oxidative spontaneous combustion of CG was further explained. The results show that the TG/DTG/DSC curves of CG in different gas atmospheres will have significant differences in all stages, and in the process of pyrolysis and oxidative combustion, the thermogravimetric curves of CG and those of the original coal show a consistent trend, except for the large difference in peak amplitude in different stages; in different gas atmospheres, as the rate of warming increases, the TG/DTG/DSC curves of the gangue are tilted toward the hightemperature region, they are inclined to the high-temperature region with the increase of the heating rate, and the phenomenon of "hysteresis" of characteristic temperature occurs. The research results provide a theoretical basis for the construction of a spontaneous combustion early warning system based on the fine division of gangue pyrolysis and oxidation combustion stages.

Section: Introductionmentioning

confidence: 99%

Study on Pyrolysis and Oxidation Characteristics of Coal Gangue Based on TGA-DSC

Jin,

Li,

Liu

et al. 2024

Self Cite

“…The heat generated by coal self-ignition affects the survival of surface crops, causing reduced production or crop failure, affecting the productivity and life of residents . Moreover, with the continuous development of technologies such as comprehensive mining and top coal caving, improvement of coal mining efficacy, increase in coal residue in the goaf, and intensification of air leakage, the risk of coal self-ignition is higher . Many technologies have been developed to reduce the possibility of spontaneous coal combustion, one of which is gel foam technology.…”

Section: Introductionmentioning

confidence: 99%

Study on the Inhibition Characteristics of Coal Spontaneous Combustion by Silica Gel Foam

Zhang,

Wen

et al. 2024

Self Cite

The spontaneous combustion of residual coal in abandoned mining areas severely affects the safe and efficient extraction of coal, employee occupational health, and regional environmental ecology. A technical measure for preventing and controlling the spontaneous combustion of residual coal involves injecting antispontaneous combustion materials into abandoned areas. In this study, the composition, preparation, and mechanism of action of silica gel foam, a material used to suppress spontaneous combustion during coal mining, were investigated to improve the performance of materials designed to prevent spontaneous combustion in abandoned areas. The inhibitory efficiency improved, and the mechanical strength and stability of the foam liquid film increased upon adding modified antioxidants and nanosilica particles to the gel foam. Macro performance tests, microstructural characterization, and chemical inhibition mechanism analyses verified the efficacy of silica gel foam for suppressing spontaneous combustion. The air leakage resistance of the silica gel foam effectively increased the air leakage resistance of the coal samples at different pressures. New radicals formed during the spontaneous combustion of coal comprising different inhibitors, as indicated by the g-factor results of electron paramagnetic resonance (EPR) spectroscopy analysis; the formation of radicals initially decreased and then increased when the inhibitor material changed. The concentration of free radicals decreased markedly during the spontaneous combustion process of both raw and inhibited coal samples at low oxidation temperatures (∼60−100 °C), indicating a marked inhibitory effect.

“…However, a few studies focus on the evolution of pore and fissure structures of coal during low-temperature oxidation. − It is of great possibility that there exists a correlation between the pore and fissure structure of coal and oxidation from the macroscopic view. Based on the mainstream theory of the cause of coal spontaneous combustion (CSC), − the theory of coal–oxygen interaction, the initial stage of the coal–oxygen interaction is a physical adsorption stage, which is mainly manifested by the migration of oxygen to the internal pores of coal . Coal pores and fractures can be used as a channel for the migration and transportation of oxygen. − At the same time, oxygen may also be able to penetrate into the interior along the surface fissures of coal and induce heat accumulation from coal oxidization.…”

Section: Introductionmentioning

confidence: 99%

“… 26 − 30 It is of great possibility that there exists a correlation between the pore and fissure structure of coal and oxidation from the macroscopic view. Based on the mainstream theory of the cause of coal spontaneous combustion (CSC), 31 − 34 the theory of coal–oxygen interaction, the initial stage of the coal–oxygen interaction is a physical adsorption stage, which is mainly manifested by the migration of oxygen to the internal pores of coal. 35 Coal pores and fractures can be used as a channel for the migration and transportation of oxygen.…”

Section: Introductionmentioning

confidence: 99%

Exploring the Effect of Low-Temperature Oxidation on the Petrophysical Characteristics of Coal

Li,

Cao,

et al. 2023

Low-temperature oxidation leads to the accumulation of heat in coal, and it is an important trigger for coal spontaneous combustion (CSC). The oxidation effects induce irreversible damage in the pore and fracture structures of coal, which provide a way for the infiltration of oxygen. In this work, the evolution of pores and cracks of coal in the progress of low-temperature oxidation is researched based on nitrogen adsorption, scanning electron microscopy (SEM), and ultrasonic testing. The results show that the oxidation effect increases microporous structures and promotes the development of mesopores and macropores in coal. Besides, as the temperature increases, the oxidation effect becomes more significant, while the pore morphology has not changed significantly yet. Meanwhile, the oxidation effect causes coal particles to block or collapse in the macropores, and the plugging degree increases with increasing temperature.