Migration And Its Environmental Effect Of Deleterious Elements In Coal During Direct Liquefaction

Taking the No.11 coal seam of the upper carboniferous Taiyuan formation of Antaibao open pit mine as a case, the research of geochemical characteristics of trace elements in sub-samples on column profile and evolution of coal-forming environment has been systematic studied. With the direct coal liquefaction test on typical sub-samples of various coal facies, deleterious trace elements group compositions and chemical structure of different solvent extracts from liquefying coal have been test and analyzed, the geological-geochemical mechanism has been explored. It concluded that the characteristics of high sulfur and high ash made the enrichment of deleterious trace elements of different liquefying coal products shows"intermix"feature. The correlation between different product yields of solvent extracts from liquefying coal and micro-macerals, pyrite(specially cryptocrystalline texture) indicated the migration of trace elements is controlled by the highly gelating components elements syngenetic combined with gelation organic components in coal, and the inorganic/organic affinity of trace elements with different solvent extracts is various. In benzene-soluble organics the trace elements compatible assemblage content decrease with the sequence of chalcophile element-siderophile element-lithophile element, while in tetrahydrofuran soluble organics the trace elements compatible assemblage content is main conclude chalcophile element-siderophile elementthe, the lithophile element assemblage content is not obvious relative to tetrahydrofuran soluble as the other two element assemblages. The coal-forming geological characteristics of high pyrite, organic sulfur, active component contents is opposite relative to the direct coal liquefaction yield, which determined the chalcophile elements, siderophile elements are the accumulate assemblage in liquefaction products. The possible environment effect of deleterious trace elements and harmful Volatile components in liquefaction products(such as gas, liquid ) and solid residue has been preliminary discussed.