title: A multi-instrumental geochemical study of anomalous uranium enrichment in coal.
abstract: Contents of uranium in coals from Odeř in the northernmost part of the Sokolov Basin, Czech Republic, in the vicinity of the well known St. Joachimsthal uranium ore deposits, reach extremely high values. In the present work, coal samples with contents of uranium ranging from 0.02 to 6 wt.% were studied. The study employing a whole complex of analytical techniques has been aimed at identification of changes in the structure of coal organic matter, which are associated with the high contents of uranium in coal. The study includes proximate and ultimate analyses, multielement analysis by instrumental neutron and photon activation analyses, micropetrographic analysis by optical microscopy, ESEM/EDX analysis of mineral matter, infrared and Raman spectroscopies, solvent extraction followed by gas chromatography with mass spectroscopy (GC/MS), and analytical pyrolysis (Py-GC/MS). The study has confirmed previously proposed explanation of uraniferous mineralization in sedimentary carboniferous substances by the mechanism of reduction and fixation of soluble U(VI) (uranyl, UO2(2+)) species (e.g., humic, carbonate/hydroxo/phosphate complexes) by sedimentary organic matter under diagenetic or hydrothermal conditions, and formation of insoluble U(IV) species as phosphate minerals and uraninite. The process is accompanied with alteration and destruction of the coal organic matter. The changes in the structure of coal organic matter involve dehydrogenation and oxidation mainly in the aliphatic, aromatic and hydroxyl structures, and an increase in aromaticity, content of ether bonds, and the degree of coalification.
authors.affiliation: Institute of Rock Structure and Mechanics, Academy of Sciences of the Czech Republic, V Holešovičkách 41, 182 09 Praha 8, Czech Republic.
authors.forename: Martina
authors.initials: M
authors.lastname: Havelcová
authors.affiliation: Institute of Chemical Technology Prague, Technická 5, 166 28 Praha 6, Czech Republic; Institute of Rock Structure and Mechanics, Academy of Sciences of the Czech Republic, V Holešovičkách 41, 182 09 Praha 8, Czech Republic.
authors.forename: Vladimír
authors.initials: V
authors.lastname: Machovič
authors.affiliation: Nuclear Physics Institute, Academy of Sciences of the Czech Republic, Řež 130, 250 68 Řež, Czech Republic; Institute of Rock Structure and Mechanics, Academy of Sciences of the Czech Republic, V Holešovičkách 41, 182 09 Praha 8, Czech Republic. Electronic address: mizera@ujf.cas.cz.
authors.forename: Jiří
authors.initials: J
authors.lastname: Mizera
authors.affiliation: Institute of Rock Structure and Mechanics, Academy of Sciences of the Czech Republic, V Holešovičkách 41, 182 09 Praha 8, Czech Republic.
authors.forename: Ivana
authors.initials: I
authors.lastname: Sýkorová
authors.affiliation: Institute of Rock Structure and Mechanics, Academy of Sciences of the Czech Republic, V Holešovičkách 41, 182 09 Praha 8, Czech Republic.
authors.forename: Lenka
authors.initials: L
authors.lastname: Borecká
authors.affiliation: Czech Technical University in Prague, Faculty of Civil Engineering, Thákurova 7, 166 29 Praha 6, Czech Republic.
authors.forename: Lubomír
authors.initials: L
authors.lastname: Kopecký
mesh_terms: D003031:Coal / Q000032:analysis*; D018153:Czech Republic; D011848:Radioactive Pollutants / Q000032:analysis*; D014501:Uranium / Q000032:analysis*
chemical_list: D003031:Coal; D011848:Radioactive Pollutants; D014501:Uranium
keywords: Coal; Organic matter; Sokolov Basin; Uranium