Uranium in Chinese coals: Concentration, spatial distribution, and modes of occurrence

Uranium in coals is an environmental radionuclide with resource utilization value. To comprehensively understand the prevalence of uranium in Chinese coals, the concentration, spatial distribution, and modes of occurrence were analyzed based on the data acquired from 1326 coal samples. Chinese coals are relatively rich in uranium, with the arithmetic and weighted average concentrations of 3.08 and 2.38 mg/kg, respectively. The regions with high uranium enrichment in coals are Guizhou, Guangxi, Yunnan, Sichuan and Chongqing, which are mainly located in southwestern China. The uranium was more enriched in Late Permian coal and medium-to-high metamorphic coal. Organic matter is the main carrier of uranium in coals, followed by silicates and sulfides. The factors affecting uranium enrichment in coal at the national scale include magma intrusions, volcanic ash, seawater influence, low-temperature hydrothermal fluids, and paleoclimate. This paper provides a reference for further research on environmental management and resource utilization of uranium in Chinese coals.