Study On Micro-mechanism Of Coal Oxidation Adsorption And Analysis Of Spontaneous Combustion Tendency

Coal spontaneous combustion accidents occur from time to time.The direct or indirect casualties and property losses are incalculable,seriously affecting the safe and efficient production of the mine.Coal spontaneous combustion is a common property of coal,but due to the difference of physical and chemical properties of coal itself,the degree of difficulty of coal spontaneous combustion is also different.Therefore,in order to avoid or reduce the occurrence of coal spontaneous combustion accidents and to find coal spontaneous combustion fires in the early stage,it is necessary to conduct a comprehensive and systematic study on the spontaneous combustion tendency of coal seams.Up to now,scholars at home and abroad have done a lot of research on the natural mechanism of coal and the difficulty of coal oxidation spontaneous combustion,but because coal spontaneous combustion is a very complex physical and chemical process,the research is still in the preliminary stage.In this thesis,a simple molecular structure model is established by combining theory with experiment.The whole reaction process of functional groups in coal oxidation spontaneous combustion is studied.The reaction path and energy calculation are carried out and the activity of functional groups is analyzed.The spontaneous combustion tendency of coal is further analyzed by using STA6000 synchronous thermal analyzer.Based on the theory of quantum chemistry and organic chemistry,the process of spontaneous combustion of coal-CH₂-,-O-CH₃ functional groups to produce water,carbon monoxide and carbon dioxide was simulated by using the software of Gaussian09.The geometric optimization of reactants,products,intermediates and transition molecules was carried out by using the B3LYP/6-311G method.The vibration frequencies of the reaction stagnation points were calculated and carried out at the same level.Reaction path?IRC?calculations confirm the authenticity of each transition state.Finally,based on molecular orbital theory,charge density calculation was carried out to verify the correctness of the order of oxidation activity-O-CH₃>-CH₂-by adding sulfur element,it was found that sulfur element increased the oxidation activity of-CH₂-by adding sulfur element.Thermogravimetric experiments were carried out on coal samples from Zisheng Coal Mine and Leopard Zigou Coal Mine.Activation energies of water loss,oxidation weight gain and ignition combustion stages during coal oxidation were calculated.The spontaneous combustion tendency of coal samples was analyzed and judged by activation energy index.It was found that Zisheng Coal Mine 2#is easier to spontaneous combustion than Baozigou Coal Mine 11#coal sample and the results were consistent with the field practice.In this thesis,the influence of-CH₂-,-O-CH₃ functional groups in coal on the tendency of coal spontaneous combustion is simulated and analyzed by using the software Gaussian09.The activation energies of various stages of coal oxidation combustion are calculated through thermogravimetric experiments,and the quantum chemistry theory is used to analyze the activation energies.It is hoped that the research on the natural mechanism of coal and the difficulty of coal oxidation spontaneous combustion will be helpful.The thesis has 27 pictures,13 tables,and 91 references.