Study On The Influence Of High Ground Temperature On Coal Self-heating Risk

Coal is one of the important basic energy sources in China.With the development of coal mining technology and the increase of mining depth,the influence of ground temperature on mines and the risk of self-heating of coal is increasing,which will seriously affect the safety of mine production and the underground workers.In this paper,a combination of experimental research and theoretical analysis was used to study the Xishan coal.Different initial temperatures were used to process the coal samples to simulate different ground temperature and environmental conditions.The high ground temperature was studied from the view of kinetics.The macroscopic and micro-characteristic parameters that affect coal spontaneous combustion have important theoretical guidance for the study of the risk of coal mine self-heating in high ground temperature environment.Using a temperature-programmed experimental system of coal spontaneous combustion and a gas chromatograph,the selected Xishan coal samples were pretreated at 30°C,40°C,and 50°C,and the treated coal samples were subjected to a temperature-programmed experiment.By analyzing parameters such as oxygen consumption rate,CO and CO₂ production rate under different temperature conditions,the three kinds of coal sample spontaneous combustion limit parameters were obtained,and the apparent activation energy in coal spontaneous combustion process was fitted,and 3#coal samples were more prone to spontaneous combustion.Analyze the basic mechanism of low-temperature oxidation process of coal,and grasps the macro-parameter change rule of coal oxidation process under high temperature environment conditions.Through the thermal analysis experiments of three kinds of coal samples,thermal analysis kinetics method was used to analyze the water evaporation stage,desorption stage and oxygen absorption gain stage in the oxidation process,and the apparent activation energy and the pre exponential factor of the three coal sample oxidation processes was obtained.The law of thermal analysis kinetic parameters was found out.At the same time,FTIR were used to analyze and study the infrared spectrum characteristics of the three treated coal samples.From the microscopic point of view,changes in peak intensity of the absorption spectrum of the hydroxyl absorption peaks,aromatic and aliphatic C-H absorption spectral peaks and aromatic C=O compounds under different conditions were studied.From the kinetics of the conversion of the aliphatic C-H component during the isothermal oxidation process,the first-order reaction model for the conversion of-CH₃ and-CH₂,and the second-order reaction model,the conversion rates of-CH₃ and-CH₂correspond to the second-order linearity reaction model,the microscopic parameters of coal oxidation process under high ground temperature conditions were obtained.Based on the changing characteristics of the macroscopic characteristics and microscopic functional groups of three coal samples,combined with the dynamic characteristics of thermal analysis,the correspondence between macroscopic gas generation rules and the changes in microscopic characteristics of different coal samples was studied,and microscopic explanation of the macroscopic characteristics of the coal oxidation process under a high temperature environment was obtained.Combining the macroscopic and microscopic characteristics,the risk of self-heating of coal under high ground temperature conditions was determined,which provided a theoretical basis and technical guarantee for further perfecting the prevention and control of coal spontaneous combustion under high ground temperature conditions.