Study On The Oxidation Reaction And Kinetics At Low Tempeature Of Jurassic Coal In North Shaanxi

The metamorphic grade of Jurassic coal seams in north Shaanxi is lower, the spontaneous combustion risk of which is very high in the mining process, not only threatening the safety of coal production, but also creating serious environmental pollution and resource wasting. Combining theoretical analysis, experimental study and mathematical method, the oxidation process, kinetics, thermal effect in macro reaction and microscopic reactivity features of the Jurassic coal in north Shaanxi were studied, and then the mechanism of spontaneous combustion of Jurassic coal was revealed. It was a very important theoretical guiding significance for forecasting and preventing the Jurassic coal spontaneous combustion in north Shaanxi.Using proximate analysis instrument, elemental analyzer, physico-chemical adsorption instrument, X-ray diffractometer, scanning electron microscope and Fourier infrared spectrometer, the coal property, specific surface area and microscopic pore structure of Jurassic coal in north Shaanxi were analyzed. And the physical and chemical structures, microcrystalline structure, pore size distribution and micromorphology characteristics of Jurassic coal were systematically studied, the characterization of affecting the adsorption property of oxygen, oxidation reaction and thermal effect of Jurassic coal in north Shaanxi were obtained. TG-FTIR experiments were conducted to study the grading characteristics in oxidation process of the Jurassic coal in north Shaanxi, and the characteristic temperature of coal spontaneous combustion and gas generating law at two stages were determined; The kinetics characteristics of the Jurassic coal in north Shaanxi at two stages of oxidation process studied by FWO and Kissinger method, obtaining the changing rules of the apparent activation energy in the coal oxidation process at low temperature. And the reaction kinetics mechanism functions at two stages of Jurassic coal in north Shaanxi were determined. The DSC experiments were conducted to analyze the thermal effect of Jurassic coal in the oxidation process, and the variation of endothermic and exothermic characteristic and the rate of thermal effects were indentified; By Fourier infrared spectrometer the microstructure in oxidation process was studied, and the key active groups and variation rule in different stages of oxidation process were finally determined.The methods of Pearson correlation coefficient and gray correlation analysis were used to analyze the correlation between the changes of active groups and apparent activation energy of Jurassic coal in the oxidation process in north Shaanxi. The impact degrees of thermogravimetric changes at the two stages by the active groups’ reactivity were different. According to the positive or negative correlation coefficient and the grey relational degree, the influence of different active groups on the oxidation reaction were characterized to determine the key active group of oxidation reaction at the two stages. Based on correlation analysis, the changing characteristics of kinetics and thermal effects in the oxidation process at low temperature were finally explained by the key active group reaction.