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Fifty-four coal clast samples in the siliciclastic rocks (e.g., sandstone and conglomerate) were collected from cores of two-deep research wells (K20H and K20K) drilled at the Kozlu coalfield in Zonguldak Basin, and for the first time, they were evaluated using mineralogy by XRD and SEMEDX and random vitrinite reflectance (%Rr) measurements in order to find out their origin and timing. Petrographic observations on polish surfaces show that the coal clasts are either entirely xylitic/vitrinitic particles or coals including a broader range of macerals. The detected minerals in the samples are mostly derived from the parental coal seams and, to a lesser extent, precipitated from penetrated pore-water in the cleats/fractures of clasts. The %Rr values of coal clasts in Carboniferous sediments are generally relatively higher than those measured in the coal seams due to weak oxidation during transportation. Furthermore, similar mineralogical and maceral compositions between coal clasts and coal seams imply that these clasts were mainly eroded during the peatification and/or early coalification of parental seams and display similar coalification patterns. The close %Rr value of a coal clast sample in the Early Aptian Zonguldak Formation and Carboniferous coal seams could suggest that this coal clast sample is presumably derived from the coal seams eroded during Early Aptian. [ABSTRACT FROM AUTHOR]

The Bozburun coalfield hosts a late Miocene 1.1 m thick coal seam. This study aims to determine coal quality, mineralogy, petrography and geochemistry, and controlling factors of elemental enrichments. The coals are generally black and greyish black in colour, and the low part of the seam commonly includes fossil shell remains. The ash yield displays a decreasing trend towards the upper part of the seam; in turn, gross calorific and total C values increase upwards. The total S content being generally higher than 5% (on dry basis), displays an increasing trend towards the upper part. In the entire seam, huminite is the most common maceral group, while inertinite and liptinite display variable proportions. The identified minerals by XRD are mainly quartz, clay minerals, calcite, pyrite, and aragonite (in fossil shell remains-bearing samples), whereas feldspars and marcasite determined in a few samples. Furthermore, in the coal samples, celestine and barite were identified by SEM-EDX. This study indicates that precipitation of celestine and Sr-bearing barite grains during diagenetic stage and Sr-uptake by mollusc within the palaeomire caused Sr enrichment in the entire seam. Overall, the water influx and redox conditions controlled the mineralogical and the elemental compositions of the coal seam. [ABSTRACT FROM AUTHOR]

This study focuses on mineralogical and geochemical compositions of feed coal (FC) and combustion residues, namely fly ash (FA) and bottom ash (BA) samples, obtained from the Kangal coal-fired power plant in central Turkey. The X-ray powder diffraction data indicate that carbonate and clay minerals are dominant phases in the FC samples. In the FA samples, quartz, hematite, anhydrite, lime, and feldspar are generally dominant and abundant phases, whereas calcite, ettringite, and portlandite are generally more abundant in the BA samples. The elements Mo, Cs, and U are significantly enriched in the studied FC, FA, and BA samples. The statistical analysis and SEM-EDX data show that Ca, Ti, and the vast majority of trace elements are inorganically affiliated, and only Tl and U have probable organic affinity in the FC. In addition, the redox conditions in the paleomires presumably resulting in Mo and U enrichment in FC, whereas their enrichment in FA and BA is most likely related to retention by CaO and Ca-sulfate. The Cs enrichment in FA is due to retention by glass. The elements in the FA and BA are distinguished into four groups according to their volatility during combustion. The elements As, Mo, Cd, Tl, and U (Group I) are the most volatile elements during combustion and condensation in the FA. The elements Li, Zn, Ga, Rb, Nb, Cs, Ba, La, and Pb (Group IV) did not become more volatile or less volatile during combustion and are located in BA. Nevertheless, Zn and Pb in the BA seem to be related to the presence of unaffected pyrite and sphalerite, and are due to low combustion efficiency of the boiler during the sampling period. Overall, enriched elements and minerals in FA and BA suggest that their disposal should be undertaken with caution. [ABSTRACT FROM AUTHOR]

The Karapınar-Ayrancı deposit is the most significant one among the recently explored coal deposits in Turkey. The aim of the present study was to determine maceral, mineralogical, and elemental compositions of coal samples picked up from one borehole (DK-7) drilled at the northern part of the deposit. The coal samples display moderate to high ash yield (average 38.7%, on dry basis), high volatile matter yield (average 33.9%, on dry basis), high total sulfur (average 6.7%, on dry basis) and low hydrogen contents (average 4.8%, dry basis). Huminite is dominant, and liptinite and inertinite appear at low concentrations. The bulk coal samples contain mainly quartz, clay minerals (mainly illite and chlorite), muscovite, feldspars, carbonates (calcite and aragonite), and rarely pyrite and gypsum/bassanite. The maceral and mineralogical compositions point to mesotrophic and rheotrophic conditions during peat accumulation; nevertheless, the inorganic intercalations show that peat formation was ceased several times. The petrographical and mineralogical compositions of coal seams in northern and eastern parts of the deposit could imply vegetation and water chemistry differences. The abundance of fossil shell-bearing layers in the studied samples could imply a slightly higher water table than this in the eastern part. In addition, higher telohuminite content might be related to a higher contribution of tree/bush peat-forming vegetation in the northern part; however, the lack of xylite-rich lithotype and the abundance of fluorinite-type resinite imply the predominance of shrubs on the palaeomire's surface. Overall, the precursor peat in the northern part of the deposit was accumulated under pure telmatic to limnotelmatic conditions, vegetation heterogeneity and ditches transporting inorganic material from the margins were developed on the surface of the Karapınar-Ayrancı paleomire. [ABSTRACT FROM AUTHOR]