Study On The Evolution Of Function Groups In Coal Gangue During Reaction Process

In the process of coal production is accompanied by a lot of waste emissions of coal gangue,and long-term accumulation of coal gangue caused by spontaneous combustion phenomenon frequently.In order to provide a theoretical basis for the spontaneous combustion of coal gangue fire accident prevention,using field investigation,theoretical analysis and experimental study of combined type,evolution of coal gangue were studied.The basic physical and chemical properties,the oxidation kinetics characteristics and functional mechanism of spontaneous combustion of coal gangue,the explanation of the.In order to provide a t heoretical basis for the spontaneous combustion of coal gangue fire accident prevention,using field investigation,theoretical analysis and experimental research methods combined with the evolution of coal gangue to study the basic physical and chemical properties,oxidation kinetics and functional groups of coal gangue.The mechanism of spontaneous combustion of coal gangue was explained.To adopted means of proximate analysis,elemental analysis,X ray diffraction,scanning electron microscopy and Fourier transform infrared spectroscopy to study coal quality and the crystal structure and morphology of the basic characteristics for coal gangue.The results show that coal gangue is characterized by high ash content and low volatile matter.It mainly exists in the form of quartz minerals.Minerals are infiltrated in floc form,and the structure is relatively loose.The thermogravimetric curves of pyrolysis and oxidation combustion of gangue at different heating rates were tested by TG-DSC combined thermal separation technology.It was found that the reaction process of coal gangue in different gas atmospheres showed phased characteristics.With the increase of the heating rate,the thermogravimetric curve moves toward a higher temperature,which leads to the phenomenon of "lag" in the characteristic temperature.At the same time,the activation energy is calculated using the Starink equation of coal gangue oxidation reaction.In the high conversion stage(a>80%),the activation energy is in a fast growing trend,while the low conversion stage(a<80%)shows a decreasing trend of activation energy first and then slowly.In situ diffuse reflectance Fourier transform infrared spectroscopy(FTIR)was used to analyze the real time changes of groups in coal gangue under different gas atmospheres.The oxidation process of free hydroxyl groups decreased linearly with temperature,intermolecular hydrogen bond and hydroxyl in-plane bending vibration has been stable,the C=C double bond groups of aromatic hydrocarbons and the substituted benzene group C-H decreases slowly,methylene symmetric and methylene antisymmetric stretching vibration of aliphatic hydrocarbon first increased and then decreased,after 200?,the C=O group in the oxygen functional group showed a tendency to increase first and then drop,the carbon oxygen bond and C-O-C groups decreases slowly,the-OH expansion vibration of carboxyl group presents a trend of exponential growth after 200 ?,and the pyrolysis process of hydroxyl group,the substituted benzene group C-H,the carbon oxygen bond,C-O-C group the change trend with temperature is consistent with the oxidation process,the-OH expansion vibrational groups?C=C group and C=O group are basically stable,methylene symmetric and antisymmetric stretching vibration first increased and then keep the same trend.