Study On Spontaneous Combustion Characteristics And Early Warning Method Of 3# Coal Seam In Juye Coalfield

The main mines of Juye Coalfield belong to deep mining mines.The main mining 3#coal seam has the characteristics of large buried depth（900～1000 m）,high temperature of surrounding rock,high initial temperature of coal spontaneous combustion（35～40℃）,and short natural ignition period,etc.At the same time,the high ground pressure is easy to break the coal pillar of the working face,which leads to the complicated air leakage law in the goaf,which significantly increases the risk of coal spontaneous combustion.Therefore,this paper takes the 3#coal seam coal samples mainly mined from three mines in the Juye coalfield（Tangkou,Xinjulong and Zhaolou coal）as the research object,using Fourier transform infrared spectrometer,synchronous thermal analyzer and coal spontaneous combustion program.The heating test device systematically studied the micro-characteristics,oxidation kinetics characteristics and the generation law of coal spontaneous combustion index gas in the oxidative combustion process of the main mining 3#coal seam in Juye Coalfield,and finally constructed a coal spontaneous combustion early warning index system of Juye Coalfield 3#coal seam.The research results can provide decision-making for the prediction and prediction of the spontaneous combustion risk in the mining process of the 3#coal seam in the Juye coalfield,and have important guiding significance for the early monitoring,early warning and prevention and control of the spontaneous combustion risk in the deep mining high geothermal coal seam.Through industrial analysis,infrared spectroscopy and other methods,the parameters of coal quality index and main functional group proportion of different coal samples were obtained.Between 1.176 and 1.642,the oxidation reaction of coal is strong and the risk of spontaneous combustion is high;the pores of coal are mainly small pores,and the pore volume and comprehensive fractal dimension from small to large are Zhaolou coal<Tangkou coal<Xinjulong coal,the contact ability of each coal sample with oxygen from small to large is Zhaolou coal<Tangkou coal<Xinjulong coal;the overall proportion of aliphatic hydrocarbons,oxygen-containing functional groups and aromatic hydrocarbons in coal It is also a key parameter that affects the spontaneous combustion characteristics of coal.The difference of the above parameters is the internal factor that causes the activation energy and oxidation gaseous products to show staged characteristics,which has an important impact on evaluating the spontaneous combustion tendency of coal and building an early warning index system.In addition,according to the Bagchi method to infer the reaction models of coal samples in different oxidation stages,it is found that Tangkou,Xinjulong and Zhaolou coals have different reaction models in the water loss and weight loss stage and the oxygen absorption and weight gain stage respectively,but the oxidative combustion stage has different reaction models.The reaction models are the same,all follow the No.7 reaction mechanism function,and the reaction mechanism of each coal sample in the later stage of oxidation is basically the same.Finally,a temperature-programmed device was used to test the gaseous products in the low-temperature oxidation process of coal,and the influence of the microstructural characteristics of the coal on the generation of gaseous products was analyzed.The initial oxidation stage（R₂,G₂）,accelerated oxidation stage（G₁,G₂）,severe oxidation stage（G₂,R₁）and oxidation of the 3#coal seam in Juye Coalfield were optimized by principal component analysis and grey correlation degree.The composite indicator gas in the decomposition stage（R₁）;according to the carbon-oxygen ratio and the characteristics of the indicator gas,the classification standard of coal spontaneous combustion four-level early warning grade is determined,and the coal spontaneous combustion risk classification early warning threshold curve is constructed based on the Logistic function;The refinement theory of spontaneous combustion stage and other regulations on coal spontaneous combustion monitoring,marker gas,critical value,ignition warning and fire management have newly constructed a six-level early warning system and indicator thresholds for early warning initial value,blue,yellow,orange,red and black.