Uranium enrichment is considerably prevalent in Jurassic coal-bearing strata in the Yili Basin. A large amount of uranium deposits (occurrences) have been discovered in recent decades. Previous studies have found that uranium deposits and coal seam have a certain correlation in their genesis and spatial distribution or sometimes uranium deposits develop directly in the coal seam. What are the geological characteristics of uranium enrichment? How is uranium enriched? How to strengthen the cooperative development of uranium and coal and environmental protection? In order to explain the aforementioned questions, the characteristics of uranium deposits, rock minerals, and geochemical and metallogenic chronology are summarized herein, and the geological control mechanism of uranium enrichment in coal-bearing strata is discussed. It is found that uranium enrichment (including sandstone uranium deposits and coal uranium deposits) has multistage genetic characteristics and is mainly spread over the gentle slope of the southern margin of the Yili basin, with its host rock possibly being sandstone, coal, and sometimes even mudstone. The uranium concentration has a considerable correlation with the reductant, and the occurrence state of uranium has both inorganic and organic affinities. In addition, uranium enrichment is believed to be a comprehensive effect of high uranium source rocks, tectonic activity, sedimentary facies, hydrogeology conditions, paleoclimate, and reductant. The difference is that uranium enrichment in sandstone is often generated in a mud-sand-mud stratigraphic structure, while uranium enrichment in coal usually develops as coal-sand-mud. What is more, strengthening the study of physical and chemical properties of the host rock, strengthening the study of uranium occurrence state, and sharing geological data are important ways for the cooperative development of coal and uranium resources and environmental protection.

Compositional characteristics of maceral and extractable organic matter (EOM) of the No. 10 coal from the Yueliangtian mine, Guizhou, Southwestern China, were analyzed by optical microscopy, gas chromatography (GC), and gas chromatography-mass spectrometry (GC-MS). The depositional conditions, thermodynamic effect, type and maturity of organic matter, and possible health hazards were evaluated. The random vitrinite reflectance (R_o) is 1.01%, and the macerals are dominated by collodetrinite, inertodetrinite, collotelinite, and fusinite. The coal seam is a terrestrial sedimentary environment of the lower delta plain through the analysis of coal facies. Additionally, the extracted yield of EOM is 1.01%. The low ratio of saturated to aromatic fraction and the distribution of n-alkanes indicate that the coal-forming plants are primarily terrestrial higher plants. Typical isoprenoid biomarker parameters, including pristane/phytane (Pr/Ph), Pr/n-C₁₇, and Ph/n-C₁₈, reflect a weak oxidizing environment of coal. The hopanoid biomarkers, odd–even predominance index (OEP), and carbon preference index (CPI) reveal that the organic matter was mature. More than one hundred polycyclic aromatic compounds (PACs) were eluted and identified, and the phenanthrenes and naphthalenes account for a higher proportion. Thermodynamic stabilities play an essential role in the conversion of molecular structures, which support the relatively high contents of 2-methylnaphthalene, 2- and 3-methylphenanthrenes, and 2,6- and 2,7-dimethylphenanthrenes compared to their respective isomers. The oxygen-containing and sulfur-containing aromatic compounds also indicate the weak oxidization of the coal-formation environment, which is consistent with the results of isoprenoid biomarkers. Because of the carcinogenicity and mutagenicity of PACs, the distribution and toxic equivalency of PACs are briefly summarized.

The occurrence characteristics of sodium and its potential relationship with macerals in Zhundong coal, as well as in Shenfu coal with average sodium levels, are investigated in this study. A new five-step sequential extraction method was first conducted for determination. The occurrence status of sodium and its related macerals in samples was determined by microscope and SEM–EDS (scanning electron microscope–energy dispersive X-ray spectroscopy). Soluble sodium salts (H₂O-Na) make up the primary proportion of sodium in Zhundong coal, at approximately 50%, while various sodium species are distributed in Shenfu coal with nonobvious differences. Inertinite contains more sodium than vitrinite does in both coals, and the highest enrichment degree of sodium was discovered in inertinite from Zhundong coal, which presented primarily as NaCl crystals (H₂O-Na) in fusinite cells, with a local weight percentage of over 15%. More specifically, H₂O-Na and insoluble Na both tend to enrich in fusinite. Additionally, it is found that maceral-rich products can be gathered using triboelectrostatic separation, and a portion of sodium can thus be removed from the coal by removing inertinite. This study may provide new insights and references regarding sodium removal from Zhundong coal.