Study On Multi-scale Characteristic Indexes Of Low Temperature Oxidation Of Coal Samples In The Same Coal Rake In Huainan Mining Area

In this paper,the method of combining theoretical analysis with experimental research is adopted.Low temperature oxidation process of coal sample from No.13-1 Coal rake in Huainan mining area.Study on the similarities and differences of macroscopic characterization and microscopic characteristics and mesoscopic heat energy release characteristics between different zones of coals in the same coal rake.Reveal the differences of spontaneous combustion characteristics of same coal rake in different zones.It is of great significance for regional coal rake spontaneous combustion prediction and prevention technology research.Firstly,the coal quality,adsorption characteristics,specific surface area and pore size distribution of coal samples in the same coal rake were systematically studied by means of industrial analyzer,element analyzer,physicochemical adsorption instrument,laser thermal conductivity analysis system,etc.Pore roughness and thermal conductivity and other physical characteristics.Then the macroscopical spontaneous combustion characteristics of low temperature oxidation process of coals in the same coal rake were studied by temperature programmed experiments.The characteristics of oxygen consumption,gas release and characteristic parameters of spontaneous combustion of coals in the same coal rake are obtained.Secondly,the exothermic characteristics of the same coal rake during oxidation at low temperature were studied by using C80 microcalorimeter,and the heat flow was obtained.Through curve fitting,the quantitative relationship between coal heat flow and coal temperature is obtained from the same exponential equations.It is found that the initial exothermic temperature of coal samples in the same coal rake is similar.The variation law of heat energy release with temperature has been mastered.Furthermore,the heat energy release of the same coal rake in different stages of oxidation at low temperature is compared and of the same coal rake in different stages of oxidation at low temperature is compared and analyzed.Using kinetic method,the apparent activation energy of three different stages in the process of low temperature oxidation of coals in the same coal rake was calculated and analyzed.It is found that the change law of activation energy of coals in the same coal rake is similar.On the whole,the activation energy of the critical temperature-dry cracking stage is lower than that of other temperature stages.At last,the microstructure and its variation of coal rake during low temperature oxidation were analyzed by XRD microcrystal structure parameters and in situ diffuse reflectance Fourier transform infrared spectroscopy(FTIR).The types and quantities of functional groups in the molecular structure of coals on the same coal rake were determined.The main active groups in the process of low temperature oxidation of coals in the same coal rake and their changing rules are mastered.Thus,a multi-scale characteristic index system for low-temperature oxidation of coals in the same coal rake is established.