Enrichment Characteristics Of Rare Earth Elements And The Main Controlling Geological Factors In Coal Of Liujialiang Coal Mine,Ningwu Coalfield

Rare earth elements and yttrium are called"industrial monosodium glutamate"and are valuable strategic metal resources.Coal seams are one of the carriers of rare earth elements and yttrium and even contain more rare earths in some coal or coal ash than those found in traditional types of ores such as carbonates,alkaline granites and weathered crusts.The study of the distribution characteristics and enrichment mechanism of rare earth elements and yttrium in coal is of great significance to the ways of obtaining rare earth elements in coal and their comprehensive utilization.In this thesis,the coal seams 2^# and 5^# of Taiyuan Formation of Liujialiang Coal Mine in Xuangang Mining Area of Ningwu Coalfield are taken as the research objects,and the geochemistry of rare earth elements in coal is the main line,and the coal quality,coal petrology,mineralogy and geochemical characteristics of major elements and trace elements in coal are studied in depth respectively,which provide theoretical support for exploring the distribution characteristics,occurrence state and enrichment mechanism of rare earth elements.The average content of rare earth elements and yttrium in Liujialiang 2^# coal is222.14?g/g and the maximum value is 293.60?g/g,while the content of rare earth and yttrium elements in 5^# coal is relatively low with the average value of 60.40?g/g.The results of coal quality analysis show that 2^# coal is medium-high ash coal while 5^# coal is extra-low ash coal,indicating that the content of rare earth elements and yttrium in coal is related to the ash content of coal.Based on coal petrography,mineralogy and step-by-step chemical extraction experiments,the occurrence state of rare earth elements in Liujialiang coal is analyzed,and the results show that rare earth elements in coal are mainly contained in silica-aluminate minerals,and clay minerals are the main mineral carriers of rare earth elements.The analysis of(La/Yb)_N-?REY and Al₂O₃/Ti O₂ ratio shows that the rare earth elements in coal originate from the Yinshan paleolith in the north.2^# coal contains granite,alkaline basalt and calcareous mudstone,and 5^# coal contains mainly calcareous mudstone.Using some environmental indicator parameters of major and trace elements,we studied the sedimentary environment of coal-forming peat swamp,established the correspondence between rare earth elements and yttrium and coal-forming environmental parameters,and explored the influence mechanism of sedimentary environment on the change of rare earth elements content.It is found that the content of rare earth elements and yttrium in coal 2^# coal correlates well with paleoclimate,paleosalinity and oxidized environmental conditions,revealing that the rare earth elements and yttrium in 2^# coal are more easily enriched under warm and humid,low salinity and oxidized conditions.In contrast,due to the low ash content and low mineral content in 5^# coal,the rare earth content will be more influenced by organic matter and has some differences from 2^# coal.In conclusion,the rare earth elements and yttrium in Liujialiang coal are mainly in the inorganic bound state,adsorbed in clay minerals and combined with organic matter in a small amount.The rare earth content in coal is mainly controlled by the recharge of land-derived debris,and secondly,the deposition environment of peat swamp also affects it.