Study on influencing factors of radon exhalation from coal measures in the northern margin of Ordos Basin

Abstract

Coal-uranium synergistic development has become an emerging research area in recent years. Radon gas emitted by uranium decay in the stratum may be used as an indicator to study the uranium-bearing area. Investigating the relationship between radon exhalation law and the depth, lithology, and mineral composition of coal measures is very important. This paper analyses the influencing factors and mechanism of radon release in coal measure strata in the Ordos Basin which is rich in coal and uranium co-occurrence deposits, by drilling a core at a depth of 18.3–84 m in the mining area, and using low-field nuclear magnetic resonance (NMR), polarizing microscope and environmental radon meter tests. The results show that the proportion of micropores decreases with an increase in particle size, and the proportion of macropores and porosity increases. High porosity has a greater effect on the release of radon gas, resulting in a higher exhalation rate in samples with coarse particle sizes. The radon exhalation rate of sandstone is higher than that of coal, and the radon concentration increases with the improved sealing property of deep rock and soil masses. The radon exhalation rate of sandstone is strongly influenced by feldspar and is positively correlated with each other. The radon exhalation was aided by the submicron structure created by feldspar alteration. The research results may be used as a reference for rock radiation risk assessment in mining areas.