Study On Coal Spontaneous Combustion Characteristics And High Efficient Resistance Technology Under Different Ground Temperature

Coal is one of the most important energy resources in our country.With the increasing demand of resources,the mining depth of mine is also increasing.The high ground temperature can change the coal structure to increase the risk of spontaneous combustion,which seriously endangers the safety of mine production.The characteristics of spontaneous combustion of coal generally include two aspects:microscopic changes and macroscopic characterization.The study of characteristics is the key to prevent and control spontaneous combustion of coal,the liquid film of traditional chloride inhibitors is easy to decompose and has short resistance life under high temperature.In order to perfect above problems,the microscopic and macroscopic characteristics of spontaneous combustion of four kinds of coal with different metamorphism were studied by simulating different ground temperature conditions（room temperature,30°C and 40°C）,a new type of inhibitor for high geothermal coal was developed and its inhibition effect and combustion quality were analyzed.By combining experimental research with theoretical analysis,the main contents and achievements are as follows:From the microscopic point of view,the characteristics of functional group change were studied by infrared spectrometer,the change law of the absorption peak intensity of hydroxyl group,aliphatic C-H,aromatic C=O and some oxygen-containing functional groups under different conditions was obtained,in the same rank coal,the number of oxygen-containing functional groups represented by hydroxyl groups increased with the increase of ground temperature,and the higher the ground temperature was,the larger the increase was,the average increase was about50%The reaction of aliphatic hydrocarbon and oxygen at high temperature consumed methylene group and produced more methyl group,the aromatic group was more stable and changed little,and the effect of ground temperature on the functional group of coal with higher metamorphic degree was more obvious.The change of weight of coal sample during combustion was analyzed by thermogravimetry,the characteristic temperature point was found by TG/DTG curve,the combustion process was divided into 5 stages,and the activation energy of pyrolysis was calculated by integral formula,the results show that the characteristic temperature of coal increases with the increase of coal metamorphism under the same ground temperature,and the characteristic temperature of coal decreases with the increase of ground temperature,especially the dry cracking temperature,increasing velocity temperature and ignition temperature,and the ground temperature has more influence on the characteristic temperature point of coal with high metamorphic degree.The activation energy of pyrolysis decreases by 5%～30%,which indicates that the high ground temperature makes the coal sample more easily reach the required temperature condition and accelerates the process of coal spontaneous combustion.The gas concentration curves of CO and C₂H₄ were analyzed by gas chromatograph,and it was found that high ground temperature decreased the critical point of the same kind of coal by about 10°C,the drying temperature decreases about20-30°C,the CO gas low temperature stage is divided into stages and the slope is calculated.In addition,at the same ground temperature,the characteristic temperature of gas increases and the amount of gas released decreases with the increase of metamorphic degree.This paper studies the macro-and micro-characteristic parameters of spontaneous combustion of coal with different metamorphism degree under high geotemperature environment,and analyzes the relationship between them,it has been used in high geothermal mine and coal storage field to restrain coal spontaneous combustion effectively.There are 46 figures,12 tables and 88 references.