Enrichment Characteristics and Controlling Factors of Critical Metals in Coal from Yunhe Mine, Jining Coalfield

Critical metals, as vital strategic resources, play an irreplaceable role in emerging energy and high-tech industries. With China’s rapid economic and technological development, research on the enrichment mechanisms of coal-hosted critical metals has become a crucial direction for alleviating resource shortages. This study focuses on the No. 3 Coal Seam in Yunhe Mine, Jining Coalfield, Shandong Province, aiming to reveal enrichment patterns and controlling factors of critical metals. A total of 12 coal, roof, and floor samples were systematically collected from the study area using stratified channel sampling methodology. Analytical techniques including X-ray fluorescence spectrometry (XRF) and inductively coupled plasma mass spectrometry (ICP-MS) were employed to determine major and trace element contents. Integrated approaches encompassing elemental analysis, rare earth element and yttrium (REY) geochemical characteristics, and provenance tracing were applied to investigate enrichment mechanisms. Results indicate: In the No. 3 Coal Seam of Yunhe Mine, Li exhibits an average content of 26.7 μg/g with a concentration coefficient of 2.23, while Th averages 6.72 μg/g with a concentration coefficient of 2.04. Both elements reach mild enrichment levels, indicating potential economic significance. Provenance analysis through w(Al₂O₃)/w(TiO₂) ratios demonstrates dominant felsic rock sources in the study area. Concurrently, comparative assessment of rare earth element (REE) fractionation patterns integrated with regional geological context reveals that the critical metals in coal were likely derived from Neoarchean granites of the Yinshan Old Land and Neoproterozoic granites within the Qinling Orogenic Belt.Furthermore, analysis of depositional environments and groundwater-seawater interactions confirms that elevated Li and Th contents in samples YH3-6 and YH3-7 resulted from a geochemical barrier formed by interactions between acidic groundwater and infiltrating seawater under reducing peat depositional conditions. In conclusion, systematic geochemical analysis elucidates enrichment mechanisms of critical metals in Yunhe Mine’s coal sequence, providing valuable insights for the exploration and enrichment assessment of coal-hosted critical metals in Shandong