Trace Elements Of The Main Coal Seams(Jurassic) In Yuxian Coalfield

Coal is the main energy in China, and there are many different kinds of traceelements in coal which are closely related to the ecological environment and humanhealth. Trace elements are also one of hot topics in the study of the current coal geology.The coal resource in Yuxian coalfield is very rich, especially the No.1coal, No.5coaland No.6coal in Jurassic Period. The research on coal origin, content, distribution andrelevance of trace elements have provided important practical significance in thecomprehensive development and utilization of coal resources and environmentalprotection.The characteristcs of trace elements, coal petrology and organic matter in Jurassiccoal (No.1, No.5and No.6coals) have been researched using the knowledge of coalgeology, coal petrology, coal geochemistry, mineralogy and sedimentology. On the basisof these preliminary analyses, the relationship and existing forms of trace elements arediscussed subsequently.A total of31kinds of trace elements in coal are detected, by using ICP-MS indetermination of trace elements content. By comparing the averages of the coal ofHuabei Jurassic, China, America and world show that part of the trace element contentis high, such as Cd, Ba, Tl, and much attention should be paid during the process ofexploitation and utilization of coal. The trace elements are relative rich near the roof anddirt band in each coal and the whole content of trace elements in bottom is higger thanthe upper in coal samples. The content of REE is low in all the3coals, but LREE isdefinitely rich comparing with HREE, Eu is clearly negative anomaly in the roof, dirtband and some coal layers though is opposite in other coal layers, the anomaly is notclear of Ce.The maturity of each coal seam is low. The Ro is about0.5%of coal, so the coalbelongs to the non-stick coal of the low rank bituminous coal. The mineral content islow, and the kinds of mineral is simple, mainly consists of clay mineral and pyriteespecially framboidal pyrite. Besides these two kinds, calcite, quartz and other mineralscan also be observed sometimes. The main minerals are quartz, kaolinite, muscovite,rutile, etc. in the roof and floor of the coal seams.By analyzing microscopic petrology and organic matter in the coal, results showthat the coal was formed under weak oxidizing to reducing wet sedimentary conditions, the source of coal-forming plants is multifarious which contains lower plant, aquaticmacrophyte and higher plants, the coal-forming environment had the characteristics ofthe inland intermountain basin.The research have found that the peat swamp environment, source rocks,coal-forming plants, mineral type and biological effect have certain influences in themigration and occurrence of the trace elements in coal. The occurrence of the traceelements in each layer of the coal has the larger correlation with the mine, littlecorrelation with the organic matter. It indicates that the trace elements are mainly inminerals. Only a small amount of several elements is in the organic combination state incoal.