There is a good positive correlation between the high-temperature environment formed by coal spontaneous combustion in goaf and the radon exhalation in coal. The higher the temperature is, the greater the radon exhalation will be. Increasing concentrations of released radon gas will accumulate in an enclosed goaf and ultimately migrate upwards to form a radon anomaly on the ground surface. Based on this principle, the surface-based radon detection method can determine the location of underground hidden heat sources by detecting high-concentration radon areas on the ground. At present, the surface-based radon detection method has been applied in multiple fire zones as an effective technique. However, the research on the mechanism of radon exhalation during coal spontaneous combustion is insufficient, which severely restricts the detection accuracy of heat source locations of coal spontaneous combustion. In this study, radon exhalation from coal samples with different degrees of metamorphism (lignite, long-flame coal, coking coal and lean coal) at different temperatures was measured, and six main factors affecting radon exhalation (moisture, specific surface area, crack development, minerals, temperature, and gas production) were further explored. The experimental results show that with the increase of temperature, the radon exhalation from coal samples increases first and then decreases. The dissolution of radon in water and the adsorption and closure of radon in capillary pores are the main existing ways of radon in coal. When the temperature rises, the radon dispersion caused by pore water evaporation and the radon migration in cracks and pores caused by coal pyrolysis are the main reasons for the significant increase of radon exhalation.

采空区煤自燃形成的高温环境与煤中的ex析出气之间具有良好的正相关关系。温度越高，the气呼出量越大。释放的ra气浓度越来越高，将聚集在封闭的采空区中，最终向上迁移，在地面上形成a异常。基于此原理，基于表面的ra检测方法可以通过检测地面上的高浓度ra区域来确定地下隐藏热源的位置。目前，基于表面的ra检测方法已在多个火区中得到了有效的应用。但是，对煤自燃过程中ex气呼出机理的研究尚不充分，这严重限制了煤自燃热源位置的检测精度。在这项研究中，测量了在不同温度下不同变质程度的煤样品（褐煤，长焰煤，炼焦煤和贫煤）中的ex析出，并研究了影响ra析出的六个主要因素（水分，比表面积，裂纹发展） ，矿物，温度和天然气产量）。实验结果表明，随着温度的升高，煤样中ex的呼出量先升高后降低。coal在水中的溶解以及capillary在毛细孔中的吸附和封闭是煤中of的主要存在方式。当温度上升时