Maceral and biomarker composition of lignite lithotypes - Implications on palaeoenvironment and grindability properties

Maceral and biomarker composition of different lignite lithotypes: matrix-coal, pale yellow xylite-rich coal, dark yellow xylite-rich coal, brown xylite-rich coal, mineral-rich coal and dopplerite originating from the Upper Miocene (“Pontian”) Kostolac Basin, Serbia was studied in detail. The objective was to establish the sources of organic matter and to determine palaeoenvironmental conditions which resulted in formation of different lignite lithotypes. Moreover, the influence of lignite lithotypes on grindability properties has also been assessed. Mineral-rich coal was formed in topogenous fresh water peat mire with open water areas. Formation of matrix coal was performed in reed march. The peatification of pale yellow- and dark yellow xylite proceeded in dry forest swamp. Brown xylite was formed in wet forest swamp, whereas dopplerite could have formed during transition of wet forest swamp into bush mire. Contents of liptinites, inertinites, gelinite, mineral matter, sesquiterpenoids, hopanoids and n-alkanes have positive impact on Hardgrove Grindability Index (HGI), whereas total huminites, telohuminite and total organic carbon content, as well as retene/2-methyl, 1-(4’-methylpentyl), 6-isopropylnaphthalene ratio exhibited negative influence on HGI

Исследование напряженно-деформированного состояния нелинейных участков магистрального газопровода Карталы-Астана

A petrological and organic geochemical study was performed on coal samples from the East field deposit, Bogovina Basin, Serbia. Fourteen coal samples were collected from different parts of the Main and Upper coal seams from fresh, working faces in the underground subbituminous coal mine. The Lower Miocene (?) coal of the East field is a typical humic coal with huminite, liptinite and inertinite concentrations of up to 81.4 vol.%, 16.1 vol.% and 13.5 vol.%, respectively. Densinite is the most abundant maceral with variable amounts of ulminite and gelinite. Sporinite and liptodetrinite are the most common macerals of the liptinite group. Exsudatinite was detected in the lower part of the Lower coal seam. Inertodetrinite is the most abundant maceral of the inertinite group. The mineral matter consists mostly of clay minerals and carbonates. The mean random huminite reflectance (ulminite B) for the Main coal seam is 0.42 +/- 0.04%Rr, and 0.41 +/- 0.04%Rr for the Upper coal seam, which are typical for an immature to early mature stage of the organic matter. The distribution and abundance of n-alkanes and steranes indicates a significant contribution of epicuticular waxes from higher plants. High amount of phyllocladane-type diterpenoids (16 alpha(H)-phyllocladane) suggests that coal forming plants were conifer families Taxodiaceae, Podocarpaceae, Cupressaceae, Araucariaceae, Sciadopityaceae, and Phyllocladaceae, while a higher amount of pimarane and norpimarane suggests Pinaceae. Taxodiaceae, and Cupressaceae. The pristane/phytane (Pr/Ph) ratio implies variable anaerobic to oxic conditions during sedimentation. The distribution of the hopanes detected in the Bogovina East field coal indicates an immature to early mature stage of the organic matter, which is in agreement with huminite reflectance. The high coal sulphur contents from the East field are characteristic for slightly alkaline depositional environments generated by bentonite from the basement of the Main coal seam. The petrological observation and biomarker composition provide evidence for the generation of immature hydrocarbons which, most probably, originated from the resins and waxes of higher plants, mostly gymnosperms. (C) 2009 Elsevier B.V. All rights reserved

Petrographical and organic geochemical study of the lignite from the Smederevsko Pomoravlje field (Kostolac Basin, Serbia)

Three Upper Miocene (Pontian) lignite seams are present in the Smederevsko Pomoravlje field (Kostolac Basin, Serbia). The origin of their organic matter (OM), the characteristics of the depositional environment and certain utilisation properties have been evaluated based on petrographic data, bulk organic geochemical parameters, biomarker patterns and their isotope signatures. Moreover, results of isotopic analysis were used for the investigation of the influence of diagenetic aromatisation on delta C-13 signatures of biomarkers. The studied lignites are typical humic coals. The OM of lignites is derived from woody vegetation and herbaceous peat-forming plants, with a strong prevalence of the former. The peat-forming vegetation is dominated by decay resistant conifers, including gymnosperm families Cupressaceae, Taxodiaceae, and Pinaceae. Angiosperms occurred in lower amounts. Minor contribution of ferns, fungi and emergent aquatic macrophyta to the biomass is also evident. Chemoautotrophic- and heterotrophic bacteria played an import role during diagenesis. Diagenetic alterations, associated with change in the number of carbon atoms, influence delta C-13 ratios. Diagenetic aromatisation of di- and non-hopanoid triterpenoids is accompanied with C-13 depletion, whereas aromatisation of hopanoids displays the opposite trend. Peatification proceeded in a fresh water environment under variable, anoxic to slightly oxic redox conditions. The lowermost coal seam III accumulated in a topogenous fresh water peat mire with open water areas, which changed occasionally into a wet forest swamp. This resulted in the deposition of mineral-rich coal. The characteristics of lignite in coal seam II are similar to those of coal seam III. This is supported also by generally similar delta C-13 values of individual biomarkers. Coal seam I is dominated by xylite-rich coal, formed under mesotrophic to ombrotrophic conditions. Rapid flooding of the bogs stopped peat growth in all three coal seams. The ratios of ring-A-degraded and non-degraded aromatic diterpenoids and non-hopanoid triterpenoids, proposed in this study, as well as degree of aromatisation of these biomarkers, reflect changes in the water table. Calorific values of the samples indicate that they meet basic requirements for utilisation in the thermal power plants. None of the lignite samples is suitable for coal briquetting, whereas, based on petrographic data, lignite from coal seam I possesses certain potential for fluidized bed gasification

Characterisation of lignite lithotypes from the "Kovin" deposit (Serbia) - Implications from petrographic, biomarker and isotopic analysis

Four lignite lithotypes (matrix coal, xylite-rich coal, mixture of matrix and mineral-rich coal and mixture of matrix and xylite-rich coal), originating from the Kovin deposit, were investigated in detail. The paper was aimed to determine the main maceral, biomarker and isotopic (delta C-13) characteristics of investigated lithotypes. Based on these results the sources and depositional environment of organic matter in 4 lithotypes were established. These samples were also used as substrates for investigation of the influence of diagenetic alteration on delta C-13 signatures of biomarkers, as well as for assessment of the most convenient utilization for each lithotype. The investigated lithotypes differ in accordance with the composition of huminite macerals. Xylite-rich coal notably distinguishes from other lithotypes beacuse of the highest content of conifer resins vs. epicuticular waxes. The mixture of matrix and mineral-rich coal is characterised by the greatest contribution of algae and fungi and the most intense methanotrophic activity at the time of deposition. In all coal lithotypes diagenetic aromatisation influenced isotopic composition of individual biomarkers. Xylite-rich coal has the poorest grindability properties. However, this coal lithotype is the most suitable for fluidized bed gasification, whereas the mixture of matrix and mineral-rich coal has the lowest applicability for this process. The calorific value decreases in order: xylite-rich coal gt matrix coal gt mixture of matrix and xylite-rich coal gt mixture of matrix and mineral-rich coal. The increase of organic carbon content and calorific value is controlled by the increase of contribution of wood vegetation vs. herbaceous peat-forming plants, as well as by stability of water table during peatification

Petrographic and biomarker analysis of xylite-rich coal from the Kolubara and Kostolac lignite basins (Pannonian Basin, Serbia)

The maceral and biomarker characteristics of 4 sublithotypes of xylite-rich coal (SXCs), pale yellow, dark yellow, brown and black, originating from the Kolubara and Kostolac lignite basins were determined. Based on these results, differences in sources and changes of organic matter (OM) resulting in formation of 4 SXCs were established. Conifers (particularly Cupressaceae, Taxodiaceae and Pinacea) had a significant impact on the precursor OM of all SXCs. The contribution of gymnosperm vs. angiosperm vegetation decreased in order pale yellow SXC gt dark yellow SXC gt brown SXC gt black SXC. The distribution of non-hopanoid triterpenoids indicates that change of SXC colour from -yellow to black is associated with reduced input of angiosperm plants from the Betulacea family. Differences in hopane distribution, bitumen content, proportion of short-chain n-alkanes and degree of aromatization of di-and triterpenoids of pale yellow SXC are controlled by microbial communities which took part in the diagenetic alteration of OM. The content of total huminites increased from black to pale yellow SXC, whereas contents of total liptinite and inertinite macerals showed the opposite trend. SXCs differ according to textinite/ulminite ratio, which sharply decreased from pale yellow to black SXC, reflecting increase in gelification of woody tissue. Regarding the composition of liptinite macerals, the SXCs mostly differ according to resinite/liptodetrinite and resinite/suberinite ratios, which are higher in yellow than in brown and black SXC. This result along with values of TOC/N ratio and Carbon Preference Index indicate that the contribution of well preserved woody material, including lignin tissue vs. the impact of epicuticular waxes decreased from yellow to black SXC

Preliminary organic geochemical study of lignite from the Smederevsko Pomoravlje field (Kostolac Basin, Serbia) - Reconstruction of geological evolution and potential for rational utilization

The study was aimed at determining the origin and geological evolution of lignites from the Smederevsko Pomoravlje field (Kostolac Basin, Serbia). The possibility of a rational utilization of the coal was also considered. For this purpose, numerous organic geochemical analyses were applied to representative lignite samples. The obtained results showed that the coal from the Smederevsko Pomoravlje field is a typical humic coal. The peat-forming vegetation was dominated by gymnosperm plants. The coal-forming plants belonged to the gymnosperm families Taxodiaceae, Cupressaceae, Phyllo-cladaceae and Pinaceae. Other precursors of organic matter (OM) were microbial biomass ferns and angiosperms. It was established that peatification occurred in a neutral to slightly acidic, fresh water environment Under anoxic to suboxic redox conditions. The maturity of the OM is low, in the phase of intense diagenetic processes. The biomarker compositions and values of the corresponding parameters revealed that the Smederevsko Pomoravlje field, the Drmno field (Kostolac Basin) and the "A" field (Kovin deposit) represent a part of a unique lignite basin. The results of this study suggest possible rational utilization of the Smederevsko Pomoravlje lignites in thermal power plants. This is particularly related to samples from coal seam I. A significant amount of gas could be generated from lignites at higher maturities. Eight samples met the basic assumptions for effective gasification

Distribution of major and trace elements in the Kovin lignite (Serbia)

A geochemical and mineralogical study was performed on lignite samples from the Upper Miocene Kovin deposit, hosting three coal seams. The Kovin lignite is characterized by high moisture content, medium to high ash yield, medium to high sulphur content and a relatively low gross and net calorific value. The mineralogical composition, and major and trace element contents were determined by X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) analyses, and inductively coupled plasma optical emission spectrometry (ICP-OES). The most abundant minerals in all lignite samples from the three coal seams are clays (illite/smectite), silicates (quartz, plagioclase), sulphates (gypsum/anhydrite) and carbonate (calcite). The other iron-rich minerals are sulphides, oxides and hydroxides (pyrite, mag-netite, haematite, and limonite). In general, mineral matter in the matrix coal consists of illite/ smectite and quartz, while xylite-rich coals, apart from illite/smectite, have a higher content of sulphates and Fe-oxide/hydroxide minerals. The lignite from the Kovin deposit is enriched in As, Cd, Co, Cr, Cu, Ga, Li, Mn, Mo, Ni, Pb, V, Zn, Gd, Tb, Er and Lu in comparison with the Clarke values for brown coals. The statistical analysis of bulk compositional data shows inorganic affinity for the majority of the major and trace elements and possible association with pyrite, illite/ smectite and calcite

Comparative study of Serbian Miocene coals - Insights from biomarker composition

The origin of the organic matter (OM) and the characteristics of the paleoenvironment of Serbian brown coals covering a time-span from the Lower to the Upper Miocene were evaluated and compared based on comprehensive petrological and biomarker analyses. Investigated coals are typical humic coals. Peat-forming vegetation is characterized by abundant decay resistant gymnosperm (coniferous) plants, followed by variable amount of angiosperms. Coal forming plants belonged to the gymnosperm families Taxodiaceae, Podocarpaceae, Cupressaceae, Araucariaceae, Phyllocladaceae and Pinaceae. Peatification proceeded in fresh water environment under variable Eh settings, from anoxic to slightly oxic condition. Upper Miocene lignites were formed in neutral to slightly acidic environment, whereas Lower and Middle Miocene coals were deposited under neutral to slightly alkaline, and more reductive conditions, which is the result of calcium-rich surface waters derived from the surrounding Jurassic to Cretaceous calcareous country rock and higher water column level. Diagenetic changes of the OM were governed by bacterial activity, rather than thermal alteration. Biomarker pattern does not significantly differ in Serbian coals of different ages. The main differences between Upper, Middle and Lower Miocene coals are expressed by higher Gelification Index (GI), proxy ratio (P-aq), n-C-23/(n-C-27 + n-C-31) and pimarane/16 alpha(H)-phyllodadane ratio, as well as lower relative abundance of C-31 alpha beta(R)-hopane of the latter one. OM of Lower Miocene coals is more mature, corresponding to immature/early mature stage (huminite/vitrinite reflectance similar to 0.45), whereas OM of Upper Miocene lignites is in immature diagenetic phase (huminite reflectance similar to 0.3). Consequently, higher gelification of Lower Miocene coals is probably an effect of higher rank, however high humidity/wet climate and low acidity within the mire could not be excluded. A good correlation between biomarker parameters and paleoclimate data is observed, indicating that biomarker patterns represent a valuable tool that reflect even slight paleoclimate changes in Serbia during Miocene

Sadržaj potencijalno toksičnih mikroelemenata u mrkim ugljevima Istočne Srbije

The contents of potentially toxic trace elements were studied on coals from four basins of Eastern Serbia. Analyses were performed by ICP-MS method in laboratory of Bundesanstalt für Geowissenschaften und Rohstoffe (BGR) in Hannover (Germany).The contents of potentially toxic trace elements in coals of Eastern Serbia is variable not only from basin to basin, but also within a basin. High As contents were detected in coals from the Senje-Resava basin (11.00 - 160.00 mg/kg), East field Bogovina basin (8.75 - 75.50 mg/kg) and Krepoljin basin (15.90 - 85.00 mg/kg), while in the other basins it is low. Selenium content is high in coals from East field of the Bogovina basin (1.11 - 28.90 mg/kg), and Mn content is high in coals from the Krepoljin basin. Increased contents of Co, Cr, Cu and Hg were detected in Senje-Resava and Krepoljin coals, and increased contents of Ni and Pb in Senje-Resava Krepoljin and East field Bogovina coals. Berilium and cadmium contents are low in all studied coals. Correlation analysis revealed that Be, Cr, Cu, Sb Co and Ni in Senje-Resava coals is most probably related to atrinite, while in coals from the other basins those elements occur within clay minerals and 'mineral-bituminous groundmass'. Manganese mostly comes from carbonate minerals.Sadržaj potencijalno toksičnih mikroelemenata (As, Be, Cd, Co, Cr, Cu, Hg Mn, Ni, Pb, Sb, Se, Th i U) proučen je na četrdeset šest uzoraka uglja donjomiocenske starosti iz Senjsko-resavskog basena (ležišta Senjski rudnik Jelovac i Strmosten), Bogovinskog basena (Istočno polje), Sokobanjskog basena (ležište Soko) i Krepoljinskog basena (ležište Centralno polje). Analize su izvršene metodom masene spektrometrije indukovane kuplovane plazme (ICP-MS) u laboratoriji Saveznog zavoda za geonauke i mineralne sirovine (Bundesanstalt für Geowissenschaften und Rohstoffe-BGR) u Hanoveru (Nemačka). U odnosu na klark za mrke ugljeve visok sadržaj arsena konstatovan je uglju Senjsko-resavskog (prosečno 45,38 mg/kg), Istočnom polju Bogovinskog (35,20 mg/kg) i Krepoljinskom basenu (52,12 mg/kg), dok je u ostalim basenima nizak. Sadržaj selena visok je jedino u uglju Istočnog polja Bogovinskog basena (3,24 mg/kg), dok su visoke vrednosti mangana konstatovane jedino u uglju Krepoljinskog basena (435,70 mg/kg). Povišen sadržaj kobalta, hroma, bakra i žive konstatovan je u uglju Senjsko-resavskog i Krepoljinskog basena, a nikla i olova u uglju Senjsko-resavskog, Krepoljinskog i Istočnom polju Bogovinskog basena