Study On Spontaneous Combustion Characteristics Of Remining Coal

In order to adapt to the sustainable development strategy of China's economy,the natural combustion and oxidation characteristics of coal after mining are changed,in order to recover the remaining resources in coal mine.It is necessary to make a deep study on it.The experimental coal samples used in this paper were selected from the remining working face of Jingezhuang 9 Coal Seam in 2008,2017 and 2019,and the spontaneous combustion characteristics of the re-mining coal were studied through experimental comparison.Firstly,the physical and chemical characteristics of re-mining coal,such as morphological development and microscopic functional groups,were analyzed by surface area and pore diameter analyzer and infrared analysis.Researches show that the coal samples in 2019 have the least micro holes and the most medium and large pores.The content of micro and macro in coal is greatly affected by the pre-oxidation temperature of70?.The oxygen-containing functional groups in coal samples reach 50%,followed by aromatic hydrocarbons and aliphatic hydrocarbons.The higher the pre-oxidation temperature is,the content of aliphatic hydrocarbon and aromatic hydrocarbon in coal decreases,and the oxygen-containing functional groups increase.The characteristics of gas concentration and oxygen consumption rate in the primary and secondary oxidation process of the re-mined coal samples were compared and studied through the programmed temperature-rising experiment,and the spontaneous combustion tendency was comprehensively judged.The results show that there are great differences in the spontaneous combustion oxidation of each coal sample before and after200?.The higher the pre-oxidation temperature is,the lower the gas concentration is.The spontaneous combustion tendency of the after coal sample decreases with the increase of the pre-oxidation temperature.The weight loss characteristics of pyrolysis,characteristic temperature and threedimensional infrared spectrum of re-mining coal in the process of oxidative spontaneous combustion were analyzed by TG-IR combined experiment.The characteristic temperature of coal samples with shorter re-mining time is lower,and the characteristic temperature of coal samples with re-mining time decreases with the increase of preoxidation temperature.The water produces during the pre-oxidation of the re-mined coal sample will evaporate and form water vapor during the secondary oxidation,which will participate in the free radical reaction to promote the further oxidation of coal.Through the study,it is find that the re-mining coal has the strongest oxidation in2019 and the weakest in 2017,because the coal samples contain the most aromatic hydrocarbons,less pore content and strong thermal stability.The oxidation property of pre-oxidized coal is stronger at 70?.The research results provide a theoretical basis for the re-mining of the coal in the unknown oxidation stage,which is of great significance to improve the yield of the coal in the re-mining safely.Figure 33;Table 13;Reference 57...