Difference of trace elements characteristics of No. 2 coal in Fengfeng mining area

To explore the occurrence of lithium( Li) and rare earth elements( REY) in coal and the differences and control factors of trace elements in coal between different mines in the same coal seam,No. 2 coal seam of Shanxi Formation in the Wutongzhuang coal mine and the Jiulong coal mine of Fengfeng mining area was studied. The coal maceral,the coal quality and trace elements characteristics of No. 2 coal seam in two coal mines were compared and ana- lyzed by the reflected light microscopy,the atomic absorption spectroscopy (AAS),the X-Ray fluorescence spectrome- ter (XRF),the inductively coupled plasma mass spectrometer (ICP-MS),and the scanning electron microscope with energy spectrum (SEM-EDX). The occurrence of Li and REY in No. 2 coal seam was studied. The difference of the trace elements in No. 2 coal seam and its influencing factors were discussed. The results show that the content of trace elements in No. 2 coal seam of the Jiulong coal mine in the middle of the Fengfeng mining area is higher than that of the Wutongzhuang coal mine in the south of the Fengfeng mining area. The average content of Li in No. 2 coal seam of the Wutongzhuang coal mine and the Jiulong coal mine is 49. 8 μg / g and 64. 3 μg / g respectively,and the average content of REY is 68. 8 μg / g and 130 μg / g,respectively. The Li and REY in No. 2 coal seam of the Wutongzhuang coal mine mainly occur in the organic matter of coal. While the Li in No. 2 coal seam of the Jiulong coal mine mainly exists in clay minerals such as kaolinite and illite,and the REY mainly occur in monazite,pyrite and clay minerals. The sediments source and the sedimentary environment of No. 2 coal seam controlled the overall characteristics of its trace elements distribution in the Fengfeng mining area,and the magmatic hydrothermal action in Yanshan Period re- sulted in the difference of trace elements in No. 2 coal seam between the Wutongzhuang coal mine and the Jiulong coal mine. The magmatic hydrothermal action mainly causes the enrichment of Li,Nb,Pb,Ta,Th,Y,La,Sm,Ce,Er,Yb in coal,and the remaining trace elements do not clearly vary. In particular,the contents of REY and Li elements increase due to the influence of magma. The average Li content in the coal of Jiulong coal mine is 14. 5 g / g higher than that of the Wutongzhuang coal mine, and the No. 2 coal seam of the Jiulong coal mine has an average REY content of 61． 2 μg / g higher than that of the Wutongzhuang coal mine. Only the Li in No. 2 coal seam of the Wutongzhuang coal mine appears to be slightly enriched,while the Li in No. 2 coal seam of the Jiulong coal mine appears to be enriched, and Nb,Pb,Ta,Th,Y,La,and Er appear a slight enrichment.