Affiliation:
1. Hebei Key Laboratory of Environmental Change and Ecological Construction, School of Geographical Sciences, Hebei Normal University, Shijiazhuang 050024, China
2. College of Geoscience and Surveying Engineering, China University of Mining and Technology, Beijing 100083, China
3. State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology, Beijing 100083, China
Abstract
As a potential strategic mineral resource, lithium (Li) in coal measures (including coal and parting) has attracted increasing attention from scholars globally. For a long time, Li in coal measures has been studied mainly on the macro-scale (whole rock); however, the microscopic characteristics of Li and Li isotope variations in coal measures are less well known. In this study, the No. 6 coal measures in the Haerwusu Mine were studied using ICP-MS, XRD, SEM-EDS, MC-ICP-MS, and LA-ICP-MS. The geochemical and mineralogical characteristics, the microscale distribution of Li in minerals, and the Li isotopes of Li-rich coal and parting in the No. 6 coal measure were investigated. The results show that the Li content in the No. 6 coal seam ranges from 3.8 to 190 μg/g (average 83 μg/g), which is lower than the parting (290 μg/g) and higher than the comprehensive evaluation index of Li in Chinese coal (80 μg/g). LA-ICP-MS imaging showed that Li in the coal is mainly contained within cryptocrystalline or amorphous lamellae aluminosilicate materials, and the Li content in lenticular aggregate kaolinite is low. The Li in parting is mainly found in illite/chlorite. The δ7Li of the coals was 3.86‰, which may be influenced by the input of the source rock. The δ7Li of the parting (7.86‰), which was higher than that of the coal, in addition to being inherited from the source rock, was also attributed to the preferential adsorption of 7Li by the secondary clay minerals entrapped in the parting from water during diagenetic compaction. Finally, by integrating the peat bog sediment source composition, sedimentary environment evolution, and Li isotope fractionation mechanism of No. 6 coal, a Li metallogenic model in the Li-rich coal measure was initially established. In theory, the research results should enrich the overall understanding of the Li mineralization mechanism in coal measures from the micro-scale in situ and provide a scientific basis for the comprehensive utilization of coal measure resources.
Funder
National Natural Science Foundation of China
Science Research Project of Hebei Education Department
Special Project for Geological Development of Ningxia in 2023
funding project of the Northeast Geological S&T Innovation Center of China Geological Survey
Reference93 articles.
1. Strategic metal mineral resources in coal measures: Significance and challenge;Dai;J. China Coal Soc.,2012
2. Strategic key metal mineral resources: Current situation and problems;Zhai;Sci. Found. China,2019
3. Ten new developments and trends in exploration practice and theoretical research of lithium deposits in China in the past ten years;Wang;Chinese. J. Geomechan,2019
4. Main types, distribution characteristics and exploration and development status of lithium deposits at home and abroad;Liu;Geol. China,2017
5. Structural control of strategic metal element enrichment and mineralization in coal measures;Cao;Coal Geol. Explor.,2023