The Coal Geochemical Characteristics Of Xishanyao Formation From Gashun Mine In Hoxtolgay Basin, Xinjiang

The study is on the basis of investigating the related achievements at home andabroad. Twenty-one coal samples and eleven parting samples (six seams) are taken fromXishanyao Formation in Gashun Coal Mine, Hoxtolgay coalfield, Xinjiang AutonomousRegion, and the samples are analyzed by using the precision instruments such asmicroscope, scanning electron microscopy analysis, inductively coupled plasma massspectrometry (ICP-MS), chromatography-mass spectrum, etc.. Making full use of thetheoretical knowledge of coal geochemistry, coal petrology, mineralogy, sedimentologyand based upon coal petrology, mineralogy, associated elements and organicgeochemistry, this paper analyzes the geochemical characteristics of coal samples fromXishanyao Formation in Gashun mine systematically. The result shows that:(1) The coal samples have lower maturity, with vitrinite reflectance about0.6%.The dominant macerals are vitrinite (av.76.6%) with minor amounts of inertinite (av.18.84%) and low liptinite (av.2.7%), along with low content of mineral matters (av.1.86%). The mineral contents are lower and mainly compose of clay minerals and pyrite,calcite, quartz. And other mineral content is less, filling in cell structure and fracture incoal, or showing crumb and disseminated form dispersed in the macerals in coal.(2) The ash content is low, and the content of trace elements are lower than itsabundance in the earth’s crust; Only the contents of Co, Ga, Sr, Ba in some layer aregreater than Chinese mean, American mean and northwest area of China’s mean. Therare earth elements contents in coal are lower than that of Chinese coal, American coaland the world’s coal, and the rare earth elements have obvious light rare earthconcentration with heavy rare earth losses. Constant elements are mainly composed ofCaO, SiO2, Al2O3and Fe2O3, and the contents of CaO and MgO in some layer are morethan the mean in the Chinese coal and American coal.(3) Based on correlation analysis between the trace element content and ashcontent in coal and organic components and the cluster analysis of trace elements andconstant elements, most trace elements of B4and B9layers are positively correlated,most of trace elements are in the inorganic mineral and less of them are in organicmacerals, which shows that occurrence form of trace elements in coal is diversity.(4) Soluble organic matter content of the coal samples is less, and saturatedhydrocarbon and aromatic hydrocarbon fractions advantage is not obvious. N-alkanes are given priority to with high carbon number distribution with unimodal typedistribution, and the main peak is C23or C25; The pristane advantage is not obvious.Main components of aromatic hydrocarbon are phenanthrene and phenanthrene withminor amounts of naphthalene series, and there are higher content of pyrene andfluoranthene series, at the same time a small amount of oxygen fluorine are detected.