Radiation- and self-ignition induced alterations of Permian uraniferous coal from the abandoned Novátor mine waste dump (Czech Republic)

Autor: Vladimír Machovič, Jaroslav Blažek, Ilja Knésl, Bohdan Kříbek, Martina Havelcová, Alexandra Špaldoňová, Ivana Sýkorová, Ladislav Lapčák
Rok vydání: 2016
Předmět:
Zdroj: International Journal of Coal Geology. 168:162-178
ISSN: 0166-5162
DOI: 10.1016/j.coal.2016.08.002
Popis: The effects of uranium mineralization and self-burning processes on inorganic and organic components of coal have been studied at a waste pile of the former Novator coal and uranium mine at Beckov (Intrasudetic Basin, Czech Republic) in order to characterize physical and chemical properties of wastes as a basis for further environmental studies. Unaltered bituminous coal was composed predominantly of vitrinite with random reflectance values between 0.72% and 0.86%, and inertinite, less common liptinite macerals, and a low level of organic solvent-extractable material (0.01–1.33 wt.%). Uranium minerals caused local radioactive alterations in the uranium-enriched coal matrix. The diameter of rounded radiation-induced haloes ranged from 0.35 to 100 μm with higher reflectance (0.84–3.44%) compared with bulk coal. Structural changes in radiation induced altered organic coal matter were characterized by low values of Raman band disorder, fewer aliphatic C H bonds and higher levels of oxygenated functional groups in micro-infrared spectra. Zones of higher reflectance were also confined to veinlets of epigenetic chalcopyrite, galena, and sphalerite mineralization, oriented perpendicularly to the coal bedding. The methylnaphthalene ratios (MNR) of extracted organic matter correlated with uranium concentrations in individual samples. In self-ignition-affected samples, the higher reflectance (1.31–1.71%), and values of Raman band disorder mirrored the intensity of burning processes. Organic matter samples located at unburnt- and burnt coal interfaces were composed of a mixture of coal macerals, char and solid bitumens. In the waste heap burning zone, coal and claystone were transformed to “clinkers” composed of plagioclase, pyroxenes, tremolite, hematite, magnetite, anatase, and aluminosilicate glass or to “paralava”, formed by porous cordierite and hematite. Organic components in the burnt-out zone were represented by small dense and massive coke particles with reflectance of 4.48%, fusinite with reflectance of 3.05% and rare coke droplets of solid bitumen (R = 1.90%). Only traces of phenanthrene and alkanes were identified in organic extracts of burnt-out rock.
Databáze: OpenAIRE
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