Application Research On Radon Exhalation And Migration Mechanism Of Coal Spontaneous Combustion In Goaf

Coal is the main resource of energy in China,and it always provideds strong guarantee for national economic construction and energy security.Coal is an Primary energy,and it's also a non renewable resource.The spontaneous combustion of coal not only wastes a lot of natural resources,but also seriously threatens the safety production of coal mine.Preliminary work of coal spontaneous combustion governance is to collect and monitor spontaneous combustion zone,spontaneous combustion prediction,fire location and fire information accurate judgment.Among them,accurate determinate the location of fire sources is the key to control spontaneous combustion,and it has been paid great attention to the safety of coal mine production.However,due to the spontaneous combustion of coal often occurs in the underground coal seam with a large depth,the spontaneous combustion area is hidden,which brings considerable difficulties to the precise location of the fire source.Isotopic radon measurement technology has many advantages such as simple operation and low cost.However,isotopic radon measurement technology is affected by many factors in the field,and its measurement value often has relative deviation.Therefore,the study of coal spontaneous combustion in goaf area especially on radon concentration in overlying the distribution and migration rule,improve the accuracy detection of radon isotope measuring technology of coal spontaneous fire has important practical significance and practical value.This paper studies the law of radon exhalation and migration in the overlying rock in the goaf based on the mechanism of the gas and microbubbles carrying radon theory.The methods of theoretical calculation,laboratory simulation and field practice were used to study the mechanism of radon exhalation and migration during the spontaneous combustion of abandoned coal in goaf.The main research contents are divided into four parts:radon exhalation migration mechanism and numerical calculation,experimental research on spontaneous combustion and radon exhalation in goaf,experimental research on simulated gas and micro bubble transport radon,and application of isotopic radon measurement technology.An overview of the main conclusions of this research work as follows:?1?In defining reaction space,along with the increase of coal temperature,precipitation concentration of radon increasing with a certain growth rate,the radon exhalation concentration change with temperature followed quadratic function distribution;with higher degree of metamorphism of coal,the greater amount of radon exhalation;The coal particle size little precipitation affects radon;Precipitation and formation of radon has certain correlation with the carbon and oxygen compounds especially the formation of carbon dioxide.?2?At single emanating medium,with increase of the distance from the radon source height,the radon value was gradually decreased;Increasing CO₂ flow has obvious enhanced the value of radon distribution,when the CO₂ flow rate reaches a certain value,enhance the rate of radon begin decay;When CO₂ air temperature increaseing,the radon increased.Under fixed gas temperature and flow condition,the value of radon value will show a tendency to decrease with the increase of height,following the quadratic function distribution.?3?Using isotope radon measuring technology,the Yaozhai mine coal spontaneous combustion fire in goaf were detected.The detection results show that:the main coal spontaneous combustion zone have three area,and the radon concentration is widely distributed,the detection results are verified by drilling.It is found that the content of carbon dioxide is high in the area of large radon value,and the concentration of its concentration is between 300 and850ppm,which can explain the fire gas such as carbon dioxide has a great contribution to the migration of radon.