Institutional Repository
Technical University of Crete
Technical University of Crete
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| URI: | http://purl.tuc.gr/dl/dias/3CD43C6F-2009-44E8-A75A-3218A2F66296 | ||
| Year | 1996 | ||
| Type of Item | Peer-Reviewed Journal Publication | ||
| License |
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| Bibliographic Citation | T. Gentzis, F. Goodarzi, C. N. Koukouzas, and A. E. Foscolos, "Petrology, mineralogy, and geochemistry of lignites from Crete, Greece", Int. J. Coal Geol., vol. 30, no. 1-2, pp. 131-150, Jun. 1996. doi:10.1016/0166-5162(95)00034-8 https://doi.org/10.1016/0166-5162(95)00034-8 | ||
| Appears in Collections |
Coal from the deposit of Plakia, Island of Crete, Greece, was examined petrologically for the determination of rank, maceral composition, and trace element geochemistry. The coal is of lignite to subbituminous B rank (%Ro,ran = 0.36-0.44). Some samples are rich in resinite. This was subdivided into two groups based on its morphological and fluorescence properties. Mineral matter in the coals consists predominantly of silicate and sulphur-bearing minerals. The low temperature ash (LTA) is dominated by quartz, illite and gypsum, whereas the mineralogy of the high temperature ash (HTA) is comprised of silicates, Fe-bearing minerals and anhydrite. The coals are enriched in the elements As, Cr, Co, Cu, Mn, Mo, Rb, Se, U, V, Ce and Nd, when compared to world coals. Thorium, Zn and most of the REEs are present in concentrations within the mean range for most coals. Bromine, Cl and Se are volatilized at 1000°C, while U, Th, V, Cr, Co, Cu, Mo and Zn are enriched in the coal ash by a factor of 2–8. Also, there are positive correlations among As, Mo, U and S in the coal, as well as between the amount of sulphur-bearing minerals in coal ash and total concentration of As, Mo and U in the coal.Sulphur content in the coals ranges from 3.5% to 5.7%; approximately 4.8–33.6% of sulphur is volatilized at 120°C and a large percentage of total sulphur is volatilized at 1000°C. This has an important implication for the use of the Plakia coals for power generation, because of the emission of SOx compounds to the atmosphere. Fluidized bed combustion and flue gas desulphurization processes are recommended to achieve reduction in trace element and sulphur emissions. The HTA is relatively acidic and the high content of SiO2 in the ash may create erosion problems in the boilers. Finally, potential problems of slagging and fouling are anticipated, based on the indices (e.g., base-acid ratio) of the lignitic ash.
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