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Experimental pyrolysis of metalliferous coal: A contribution to the understanding of pyrometamorphism of organic matter and sulfides during coal waste heaps fires

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    0545841 - ÚSMH 2022 RIV NL eng J - Journal Article
    Kříbek, B. - Bičáková, Olga - Sýkorová, Ivana - Havelcová, Martina - Veselovský, F. - Knésl, I. - Mészárosová, Noemi
    Experimental pyrolysis of metalliferous coal: A contribution to the understanding of pyrometamorphism of organic matter and sulfides during coal waste heaps fires.
    International Journal of Coal Geology. Roč. 245, SEP 1 (2021), č. článku 103817. ISSN 0166-5162. E-ISSN 1872-7840
    R&D Projects: GA ČR(CZ) GA19-05360S
    Institutional support: RVO:67985891 ; RVO:67985831
    Keywords : Coal pyrolysis * Organic products * Coke properties * Elements volatility * Sulfide melting
    OECD category: Environmental sciences (social aspects to be 5.7); Environmental sciences (social aspects to be 5.7) (GLU-S)
    Impact factor: 6.300, year: 2021
    Method of publishing: Limited access
    https://www.sciencedirect.com/science/article/pii/S0166516221001440?via%3Dihub

    Thermal metamorphism of original coal adjacent to burning centers in coal waste heaps is a common phenomenon, and semi-coke and coke are formed during this process. In this study, changes taking place during the pyrolysis of both organic and inorganic constituents of coal in burning heaps are interpreted, and the volatility of major and trace elements is assessed. Experimental pyrolysis of bituminous coal from the coal and uranium Nov acute accent ator Mine (Czech Republic) was carried out at temperatures of 200 degrees C, 500 degrees C, 700 degrees C and 900 degrees C. Changes occurring at various temperatures of pyrolysis in the coal matrix were studied by methods of coal petrography, organic and inorganic geochemistry. Due to the high contents of sulfides of Fe, Cu Zn and Pb in coal, changes in their chemical composition which occur during their melting were also studied. The results showed that with rising temperature the amount of gas produced during the pyrolysis increased significantly while the amount of released nitrogen from coal organic substance and CO2 decreased and, conversely, the H2 content was increasing significantly. The largest amount of tar originated at a temperature of 500 degrees C. Coke and semi-coke appeared in the solid residue already at a temperature of 500 degrees C and, as the temperature increased, its porosity and optical reflectance were gradually increasing. The results of gas chromatography/mass spectroscopy (GC/MS) showed that the pyrolysis was associated with a rapid decline in the extractability of solid products of pyrolysis. The maximum concentration of polycyclic aromatic hydrocarbons (PAHs) in coke was recorded at 500 degrees C (28.5 rel.% of identified compounds), and then dropped to 11 rel.% at 900 degrees C. The concentration of Hg in the solid residue after the pyrolysis declined significantly even at temperatures of <500 degrees C. At higher temperatures, apart from Hg, the amount of In, Sb, Tl, Zn, As, Mo, Sn, Pb, Se, Hg and Cd in the pyrolysis residuum gradually decreased, which corresponds to the presence of sulfides of the above elements in the mats of coal fire gas minerals (CFGM) on the surface of many burnt coal heaps. Galena was partially melted during the pyrolysis already at a temperature of 700 degrees C to form metallic Pb. However, a significant increase in the volume of melts occurred when the temperature reached 900 degrees C with the formation of mineral assemblage consisting of galena metallic Pb pyrrhotite sphalerite intermediate Cu-Fe solid solution phase (iss) bornite. Consequently, the melting of sulfides during the pyrolysis can be one of the reasons for high volatility of some chalcophile elements in the processes of coal pyrolysis in burning heaps.
    Permanent Link: http://hdl.handle.net/11104/0323093

     
     
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