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The shale gas exploration of the Longmaxi Formation in the Yangtze Region of China has made a significant breakthrough. As an important hydrocarbon generation organism, graptolite is widely distributed in the Longmaxi Formation shales, but its hydrocarbon potential is still unclear. Taking the Longmaxi Formation shales in the Middle Yangtze Region as an example, this paper discusses the organic petrological characteristics of graptolite and its contribution to buried organic carbon. The Longmaxi shales in the study area can be divided into organic-rich shales (TOC > 2.0%) and organic-bearing shales (TOC < 2.0%). The organic-rich shales have high quartz content and low clay mineral content, which is opposite in the organic-bearing shales. Organic maceral results show that graptolite is widely distributed in nearly all the samples, while solid bitumen is relatively developed in organic-rich shale. The equivalent vitrinite reflectance obtained from the conversion of graptolite reflectance ranges from 2.46% to 2.76%, indicating that the organic matter maturity of the Longmaxi Formation shale is overmature. Combining an optical microscope and a field emission scanning electron microscope, the proportion of graptolite area to organic matter area can be obtained, the average of which is 32.71%. Solid bitumen mainly contributes to buried organic carbon of the organic-rich shales in the Longmaxi Formation, while graptolites contribute little to organic carbon burial. However, solid bitumen in the organic-bearing shales is relatively undeveloped, and graptolite is an important hydrocarbon generation organism, which is the main contributor to buried organic carbon.

Coal‐bearing source rocks of the Pinghu Formation in the Xihu Depression comprise an important material basis of oil and gas resources in the East China Sea Basin. Based on drilling core observation results combined with the analysis and test results of macerals, trace/rare earth elements, and rock pyrolysis, the geochemical characteristics and sedimentary control of coal‐bearing source rocks formation are discussed in a high‐frequency sequence framework. The results indicate that the macerals composition of the coal‐bearing source rocks of the Eocene Pinghu Formation in the Xihu Depression is dominated by vitrinite, with low‐medium abundance of exinite and almost no inertinite. The coals and carbonaceous mudstones display higher amounts of total organic carbon (TOC) (14.90%–65.10%), S1 + S2 (39.24–136.52 mg/g), and IH (191–310 HC/g TOC) respectively, as compared to the mudstones. Organic matter is plotted in type III kerogens and partially in type II; it is mainly in the low maturity stage. The trace elements results imply that the samples were deposited in a weakly reducing to weakly oxidizing environment and were occasionally affected by seawater. The coal‐bearing source rocks were deposited in a relatively oxygen‐containing environment. The coal‐bearing source rocks development is jointly controlled by the coal accumulation environment, the water conditions affected by ocean currents in offshore basins in China, oxidation–reduction cycles of aqueous media and paleoclimate evolution in a high‐frequency sequence framework. [ABSTRACT FROM AUTHOR]

The pore structure of lignite reservoirs is affected mainly by the maceral composition of coal and depositional conditions due to geothermal effects without thermogenic hydrocarbon generation. Low-temperature nitrogen adsorption (LT-NA) and low-temperature carbon dioxide adsorption (LT-CA) were used to characterize nanopore structure. Sub-maceral identification allowed characterization of coal petrology features. The coal samples were rich in huminite—mainly attrinite and densinite—and had medium inertinite content, dominated by fusinite. The micropore volume varied from 0.036 to 0.077 cm3/g, controlling the pore specific surface area. Three pore types were identified from LT-NA isotherms. Hysteresis coefficients were used to describe quantitatively the pore types. Low tissue preservation index and vegetation index, moderate gelification index, and groundwater influence values indicate that the No. 5 coal seam (Shengli coalfield, Erlian basin, China) was deposited in limnic to limno-telmatic environments with relatively high levels of reduction and supply of marginal aquatic/herbaceous vegetation. Poor preservation of plant structure and hydrodynamic conditions, more developed marginal aquatic/herbaceous vegetation, and high ratio of huminite to inertinite contributed to high micropore content and low mesopore content. Based on sharp variations in coal macerals, coal facies indices, dried ash yield (Ad), and organic sulfur (So,d), three sedimentary cycles were distinguished. Pore structures were controlled by the sedimentary environment. Micropores increased with enhanced reduction and reduced oxidation. When the redox of the sedimentary environment showed little variation, mesopores increased with rising hydrodynamic conditions. [ABSTRACT FROM AUTHOR]

This study presents the details of petrographic and chemical characterizations of the Cenozoic coal from the Hongsa coal mine, Xayabouly Province, Lao PDR. Eighty-nine samples from a drill core consist mainly of lignite, carbonaceous clays, and clays. From the petrographic study, the Hongsa coals are dominated by huminite, followed by liptinite, and the very few funginite of the inertinite group. They show both features of humic and sapropelic coals. A moderate amount of mineral matters are silica and clay minerals. Based on maceral and mineral assemblages, they indicate a forest swamp environmental setting with a moderate amount of sediments supplied by low-energy water flow. Moreover, the characteristics of maceral preservation indicated the depositional environment was an anoxic condition with low oxidation. The limnotelmatic environment points to the deposition of peat between an open moor and a wet-forest moor environment. According to a chemical analysis, the coals are classified as lignite A and lignite B with high ash content and low sulfur. [ABSTRACT FROM AUTHOR]

For the purpose of evaluation of suitability of the Kalewa fossil coal deposit (Kalewa, Myanmar) for the production of granular active coals, the results of its petrographic analysis in the form of maceral composition and an arbitrary vitrinite reflection index are characterized, indicating the potential possibility of its use for solving this problem, based on the data of thermographic tests performed in a protective atmosphere, the rational limits of the thermal effect on this raw material during pyrolysis are estimated, the rational conditions of this process and the activation of its carbonized residue by water vapor are presented, the low efficiency of steam activation is shown, and the results are presented. The results of the chemical activation of the named fossil coal by alkaline agents in the form of NaOH and KOH, indicating the possibility of obtaining active coals with structural and adsorption properties acceptable for practical use, the conclusion is made that the processes need to be improved. [ABSTRACT FROM AUTHOR]

The concentrations and distributions of industrially valuable trace elements associated with germanium in the coals of the Spetsugli section of the Pavlovsk brown coal deposit in Primorskii krai was studied using mass spectrometry and laser microanalysis. The concentrations of a number of metals in traditional types of ores at a minimum industrial level were established. Geochemical associations of industrially valuable metals and other impurity elements were identified. Maximum concentrations of many trace elements in low-ash coals were noted. The distribution of a number of trace impurity elements in the coal matter and the macerals of coals was studied, and conclusions on the genesis of trace elements were drawn. [ABSTRACT FROM AUTHOR]

The high volatile C bituminous-rank, Bolsovian-age Princess No. 3 coal, a correlative of the heavily-mined Hazard No. 7 coal and the Peach Orchard and Coalburg Lower Split coals, was investigated three sites at a mine in Greenup County, Kentucky. The coal exhibits a "dulling upwards" trend, with decreasing vitrinite and a greater tendency towards dull clarain and bone lithotypes towards the top of the coal. The relatively vitrinite-rich basal lithotype is marked by a dominance of lycopod tree spores. The palynology transitions upwards to a middle parting co-dominated by tree fern and small lycopod spores and an upper bench dominated by tree ferns with contributions from small ferns, cordaites, and calamites. The lithotypes generally have a moderate- to high-S content with a variable ash yield. Sulfur, Fe2O3, and certain siderophile elements are highest near the top of the coal. As observed in other coals, uranium and Ge are enriched at the top and bottom margins of the coal. The rare earth chemistry at the top of the coal has a significantly lighter distribution (higher LREE/HREE) than at the base of the coal. [ABSTRACT FROM AUTHOR]

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Catastrophic cases of methane explosion during exploratory drilling within the Bełchatów ortholignite deposit have led to testing for methane in other Polish ortholignite mining areas, as well as in the Złoczew deposit, where it is planned to begin mining operations. Initial tests have shown Złoczew lignite to have the highest methane content among the Polish deposits so far studied, comparable with lignite from the Bełchatów deposit, with a methane capacity in excess of 2.5 dcm3/kg at a pressure of 10 bar. Based on the computed values of the Langmuir constant, a determination was made of the quantity of methane that can be desorbed from a pressure of 10 bar to 1 bar, as well as the residual methane content. For all of the tested samples, the residual methane content is between 30 and 50% of the sorption capacity at a pressure of 10 bar. The thermal sorption equations were used to compute values of the limiting isosteric heat of adsorption. Higher values of the heat of adsorption at zero surface capacity may indicate the presence of a small quantity of micro-pores. In the case of the samples with the highest sorption capacity, the limiting isosteric heats of adsorption are low, indicating a low proportion of micro-pores in the lignite. This was confirmed by tests of nitrogen adsorption at 77 K. The proportion of micro-pores in the studied lignites is 2–3%, while the dominant pore fraction is the meso-pores, which in lignite from the Złoczew and Bełchatów deposits account for 50–66% of total pores. It is concluded that the significant adsorption of methane in the ortholignite occurs chiefly in meso-pores because of compression of the gas under increased orogenic pressure. A link is made between the higher methane-bearing capacity of the ortholignite deposits and the degree of gelification of the huminite components, based on simple statistical correlations between the methane sorption capacity and the content of humic gelified maceral. The results concerning methane sorption in lignite from the Złoczew deposit have enabled a preliminary classification of the methane-bearing capacity of Polish ortholignite deposits, which may also be of significance for similar deposits in other countries. [ABSTRACT FROM AUTHOR]

This review presents a mineralogical and physicochemical comparison of coal seams located in the regions of Northwest and Central Greece. The comparison extends to the fly ash derivatives from the coal combustion for energy production, in the cases where data are available. Coal occurrences from Northwest Greece tend to exhibit higher content of rare earth elements (REE) compared to those of Central Greece. Moreover, fly ash products show similar trends in Light-REE compared to their coal parent rocks. The observed REE distribution seems to be correlated with the occurrence of specific minerals such as allanite, monazite, as well as with Fe-contents.

Bu çalışmada Sinanpaşa (Afyon) Neojen havzası içerisinde iki bölgede (güneyde Kırka bölgesi, kuzeyde Karacaören bölgesi) yer alan kömür örneklerinin petrografi k ve palinolojik incelemeleri yapılmıştır. Kömür içeren Neojen tortulları beş fasiyese ayrılarak incelenmiştir. Bunlar alttan üste doğru; paleosol, bağlayıcı destekli çakıltaşı, kömürlü çamurtaşı, kumtaşı-kiltaşı ve laminalı çamurtaşı fasiyesleridir. Kömürlü seviyeler belirgin olarak kömürlü çamurtaşı fasiyesi içerisinde yer almaktadır. Ayrıca bağlayıcı destekli çakıltaşı ile kumtaşı-kiltaşı fasiyeslerinde de çeşitli boydaki kömürleşmiş malzemeye rastlanmaktadır. İnceleme alanından derlenen örneklerin kömür petrografi si incelemeleri yapılmış ve bunlara bağlı olarak kömürlerin çökelme ortamları ile ilişkili yorumlamaya gidilmiştir. Buna göre bu kömürlerin başlıca gelinitçe zengin olan hüminit maseral grubunu içerdiği, Rmax değerlerine göre alt bitumlu kömür sınıfl amasına girdiği ve göllerle ilişkili bataklık zonlarında çökeldiği sonucu ortaya çıkmaktadır. Örneklerin derlendiği düzeye ait palinolojik veriler kömürlü birimlerin yaşının Orta Miyosen olduğunu işaret etmektedir. Paleoiklim çalışmaları sonucunda elde edilen MAT, CMT, WMT ve MAP parametrelerine dayanarak çalışma alanındaki iklimsel koşulların mevsimselliğe bağlı olarak değiştiği gözlenmiştir. Sonuç olarak, kömürlü seviyelerin oluştuğu dönemde ılıman iklim koşullarının varlığından söz edilebilir.

Metallurgical cokes, as fuel for blast furnaces, have certain properties which are directly related to their blended parental coal characters. The maximum fluidity (MF) of coal as an energy index is typically used to estimate the coke properties. In this investigation, Support Vector Regression (SVR), as an intelligent method, has been applied to link characteristics and pyrolysis properties of coal samples with their representative MFs. SVR variable importance measurement (VIM) through a wide range of coal properties indicated that volatile matter (VM) and maximum vitrinite reflectance (Rmax) are the most effective parameters for the MF prediction. The results indicated that low rank coal samples (VM>45% and Rmax>0.7) have log(MF) higher than 14 and high rank ones (VM<35% and Rmax<0.6) have log(MF) less than 4. The evaluation of the SVR model trained with these two selected input variables showed that SVR can predict MF quite accurately where the coefficient of determination (R2) between actual MF and SVR predicted was 0.86. According to these results, generation of SVR models which can predict and measure variable importance dependently, potentially may be applied for the scaling up of laboratory coal thermoplastic behavior to industrial levels, helping to sustainable development, and satisfactorily estimating coal consumption in the steel-making plants. [ABSTRACT FROM AUTHOR]

In this study, effects of petrographic composition and particle size on flotation process were investigated. Samples were taken from rougher and cleaner cells of central Alborz coal washing plant (Iran). Petrographic study of the feed into flotation circuit with different size fractions showed that an increase in particle size tends to decrease vitrinite and inertinite macerals percentage while increasing that of liptinite. Petrographic analysis of different size fractions of rougher and cleaner cell concentrates showed that, with increasing particle size, vitrinite macerals were reduced but liptinite macerals showed an increase. Evaluation of the cell operation revealed that over 62% of tailings was composed of reactive macerals in coking process, including vitrinite and liptinite. The petrographic study showed that, with the same frother, by applying gasoline as a collector, yield, and total recovery increased by 3.5% and 3%, respectively, as compared to those when kerosene served as collector. Continuing with gasoline as collector, total circuit recovery increased by 2.2% when methyl isobutyl carbinol (MIBC), rather than pine oil, served as frother. Based on petrographic studies and percentages of reactive macerals, the optimal reagents were found to be gasoline (as collector) and MIBC (as frother). [ABSTRACT FROM AUTHOR]

Knowledge of the way in which minor and trace elements occur in coal is one of the most important geochemical indicators of coal quality. The differences between the methods of binding elements in coal in each coal seam and the variability of this feature of coal in the basin profile have not been discussed so far. These coal features were identified in a group of selected coal seams (209, 401, 405, 407, 501, 504, 510, 615, 620) in the Upper Silesian Coal Basin (USCB). At the same time, the differences in the role of identified mineral and maceral groups in concentrating specific elements in coal is highlighted. Identical or similar tendencies of changes in the way in which As and V, Ba and Rb, Co and Pb, Co and Zn, Mn and Pb, Pb and Zn, Co and Rb, and for Cr and Cu occur in the coal seams in the USCB profile was found. Changes in the mode of occurrence of As and Pb in coal in the USCB profile were probably influenced by carbonate mineralization. The changes in the mode of occurrence of Mni and Pb in the coal were probably determined by dia and epigenetic sulfide mineralization, while the content of Ba, Cr, Rb, Sr, and V in coal from these deposits was affected by clay minerals. It was observed that the greater the degree of the carbonization of the organic matter of coal, the lower the content of As, Mn and Pb in coal and the higher the content of Ba and Sr in coal. [ABSTRACT FROM AUTHOR]

Organic matter-rich rocks occur in the Carpathians, both in the Lower Cretaceous and Oligocene. Whereas, the Oligocene Menilite Formation has been intensely studied, the hydrocarbon potential of Lower Cretaceous rocks is less well understood. In the present paper a 405 m thick succession of the lower part of the Shypot Formation in the Chornohora nappe (Ukraine) is studied using 94 outcrop samples. Maturity parameters for the Lower Cretaceous rocks indicate peak oil maturity (~0.85 % Rr) and organic carbon content averages 2.8 wt. % for all samples. As a result of the enhanced maturity, the hydrogen index (88 mg HC/g TOC) and the remaining petroleum potential (2 tHC/m²) are low. Comparisons with coeval rocks from the same tectonic unit, but with lower maturity suggest that the original petroleum potential was significantly higher (4 tHC/m²). Probably about 2 tHC/m² were generated during deep burial (6 km?), but were lost during uplift and erosion. Macerals analysis reveals a mixed type III-II kerogen, with domination of terrigenous components, which is also supported by HI values of nearby marginal mature samples (~200 mg HC/g TOC). Lower Cretaceous organic matter-rich rocks are found along the entire Carpathian arc. A compilation of published data for age-equivalent rocks across the Carpathian Fold-Thrust Belt shows that HI values are mainly controlled by maturity as well as the moderately high original HI values. Most of these rocks contain predominantly type III-II kerogen, whereas Lower Cretaceous rocks in the Skole-Skyba nappe near the Polish--Ukrainian border contain type (III-) IV kerogen. [ABSTRACT FROM AUTHOR]

Raman spectroscopy and vitrinite reflectance measurements of dispersed organic matter from Carboniferous shales in boreholes in the northern part of the Intra-Sudetic Basin were used for thermal history reconstruction. Microscopic investigations have shown that the organic matter is dominated by the vitrinite maceral group. In analysed samples, organic matter shows a varied degree of thermal alteration determined by the mean random vitrinite reflectance (VRo) ranging from 0.72% to 3.80%. Mean apparent maximum vitrinite reflectance (R'max) values reached 4.98%. The full width at half maximum of D1 and G bands in Raman spectra are well-correlated with mean VRo and R'max. Thermal maturity in the boreholes shows a regular increase with depth. Geological data combined with Raman spectroscopy and mean vitrinite reflectance results indicate that the analysed Carboniferous strata reached maximum paleotemperatures from c. 110 to c. 265°C. The regional paleogeothermal gradient in the late Paleozoic was c. 80°C/km. The Variscan heating event presumably caused a major coalification process of organic matter. The Carboniferous-Permian magmatic activity must have contributed to high heat flow, adding to the effect of sedimentary burial on the thermal maturity. [ABSTRACT FROM AUTHOR]

This paper presents the results of laboratory tests conducted on a series of mini-cylinder specimens to measure the uniaxial compressive strength of sub-bituminous coal, which is sparsely recorded in the public domain. The measurements were made on mini-cylinder specimens (non-standard) sized from 9.3 to 22.6 mm in diameter, sourced from the Surat–Clarence–Moreton Basin in Australia, an important region for coal mining and coal seam gas extraction. The tested specimens presented poorly developed cleats and were texturally classified as non to poorly banded, although the composition is rich in vitrinite group macerals. The inherent variability of experimental coal strength results was found to be related to fabric and texture. The results from the mini-cylinder specimens could be scaled to predict the behaviour of larger core sizes commonly used for testing mechanical variability and for estimating full seam rock mass strength. [ABSTRACT FROM AUTHOR]

This paper aims to explore the disseminated characteristics of minerals in this kind of middling coking coal as the washed middling coal of some coking coal preparation plants is still difficult to disassociate after deep crushing. The difficult-to-dissociate middling coking coal was carefully prepared, the optical microscopy and scanning electron microscopy incorporated with energy dispersive spectroscopy (SEM-EDS) measurements of the middling coking coal were conducted to analyze the disseminated granularity and form of minerals in the middling coking coal. The results show that the minerals that are difficult to disassociate from middling coking coal are mainly clay minerals such as kaolinite, which was in the forms of fine granules, strips, disseminated, filled fissures, and cavities. The particle size of the disseminated clay minerals in the coal sample was only a few microns or even smaller. In addition to clay minerals, the minerals such as pyrite, calcite, and quartz were also observed in the middling coking coal. These minerals accounted for a relatively small proportion, but their grain sizes are very fine and their disseminating forms are very complex. [ABSTRACT FROM AUTHOR]

Organic matter-rich Middle Jurassic rocks occur in the Mesozoic basement of the Carpathian Foredeep in Ukraine. Eighty-nine core samples from the Mosty-2, Korolyn-6 and Korolyn-2 wells as well as three oil samples from the Kokhanivka and Orkhovychi oil fields in the Kokhanivka Zone, were investigated. Bulk geochemical data as well as maceral analysis have been determined, and a subset of these samples, including all oil samples, have been investigated for biomarker composition. Middle Jurassic strata are rich in organic matter (average: 4.19 wt. %) and reach TOC contents of up to 14.98 wt. %. However, HI values are low, typically around 100 mg HC/g TOC, and only reach a maximum of 242 mg HC/g TOC, indicating dominance of gas-prone, Type III kerogen. Tmax values as well as random vitrinite reflectance measurements for the Mosty-2 (434 °C; 0.69-0.71 % Rr), Korolyn-6 (443 °C; 0.78-0.82 % Rr) and Korolyn-2 (448 °C; 0.85-0.90 % Rr) wells indicate that thermal maturity increases with depth from marginally mature to mature, suggesting that hydrocarbon generation may have occurred. However, biomarker data suggests no genetic link between these rocks and Upper Jurassic oils, as C27-C28-C29 sterane distributions, Pr/Ph ratios, DBT/Phenanthrene ratios and isotope data display significant differences between the two. New geochemical data, along with published biomarker data on Upper Jurassic rocks and crude oils belonging to the same oil family as the Upper Jurassic oils in the Ukrainian Carpathians, showed that Upper Jurassic rocks from the Korolyn-6 well present a better fit and are the source for the analysed oils. [ABSTRACT FROM AUTHOR]

In this paper, an attempt is made to recover vitrinite-rich fraction coal using batch flotation operation. Three important operational variables, viz. collector dose (kg/ton), frother dose (kg/ton), and feed solid concentration, (%) have been changed according to Box–Behnken factorial design and their effect on the response parameter like yield, ash, and vitrinite maceral recovery (vmr) percent has been evaluated. For understanding the influence of interactional effects, response surface methodology (rsm) approach has been adopted. From 69.23 to 99.98 of volume percentage of vitrinite maceral is recovered, when the flotation test is performed without addition of collector with frother level maintained at 0.75 kg/ton of coal keeping feed solid concentration fixed at 5% solid by weight. High value of R2 greater than 90% is obtained for model equations of yield, ash, and vmr. Minitab 16.0 statistical software was used for data analysis. [ABSTRACT FROM AUTHOR]

The macerals effective dissociation is the precondition for the macerals enrichment. The macerals dissociation generally adopts the crushing and grinding process. Selective grinding is achieved by using the differences in mechanical properties between different macerals, and grinding equipment and grinding time are important factors affecting the degree of selective grinding. Hence, it is necessary to choose the suitable dissociation method, control the suitable dissociation time, avoid over-crushing, and then cooperate with the suitable concentration methods to achieve macerals efficient enrichment. In this paper, the low-rank coal studied was produced by Shenhua Shigetai Coal Mine. Coal sample was crushed to less than 1 mm and then was carried out for the grinding test by using the rod mill and the ball mill, respectively. In order to determine the macerals dissociation characteristics of Shenhua low-rank bituminous coal, the size distribution, density level, and macerals of the grinding products under the different grinding equipment and grinding time were analyzed. The test results show that the grinding effect of the rod mill is better than that of the ball mill under the same grinding time, and 10 min rod grinding can obtain the best macerals dissociation. [ABSTRACT FROM AUTHOR]

Coal measure source rocks, located in the Xihu Sag of the East China Sea Shelf Basin, were analyzed to define the hydrocarbon generation potential, organic geochemistry/petrology characteristics, and coal preservation conditions. The Pinghu source rocks in the Xihu Sag are mainly gas‐prone accompany with condensate oil generation. The coals and shales of the Pinghu Formation are classified from "fair" to "excellent" source rocks with total organic carbon (TOC) contents ranging from 25.2% to 77.2% and 1.29% to 20.9%, respectively. The coals are richer in TOC and S1+S2 than the shales, indicating that the coals have more generation potential per unit mass. Moreover, the kerogen type of the organic matter consists of types II‐III and III, which the maturity Ro ranges from 0.59% to 0.83%. Petrographically, the coals and shales are dominated by vitrinite macerals (69.1%–96.8%) with minor proportions of liptinite (2.5%–17.55%) and inertinite (0.2%–6.2%). The correlation between maceral composition and S1+S2 indicates that the main contributor to the generation potential is vitrinite. Therefore, the coals and shales of the Pinghu Formation has good hydrocarbon generation potential, which provided a good foundation for coal measure gas accumulation. Furthermore, coal facies models indicates that the Pinghu coal was deposited in limno‐telmatic environment under high water levels, with low tree density (mainly herbaceous) and with low‐moderate nutrient supply. Fluctuating water levels and intermittent flooding during the deposition of peat resulted in the inter‐layering of coal, shale and sandstone, which potentially providing favorable preservation conditions for coal measure gas. [ABSTRACT FROM AUTHOR]

The organic richness, thermal maturity, oil generation potential, liquefaction behavior hydrocarbon generation potential and geochemical properties of 12 lignite samples from Umarsar lignite mines of Kutch district, Gujarat, India were investigated. The lignite samples studied shows that they are significantly rich in total organic carbon (TOC) content which varies from 36.92 to 51.99 wt%. Tmax and HI index value show that these thermally immature lignite contains Types II-III and Type III kerogen; which is also anticipated from plot between released hydrocarbon (S2) yield and TOC. The cross plot between HI index and TOC demonstrates that the samples fall in fair oil source. The reflectance value varies from 0.23% to 0.28% and confirm it is immature in nature. The huminite maceral (>70.34%) dominates while liptinite >15.53% and inertinite occur in subordinated amount. High quantity of huminite and liptinite macerals shows its aptness towards liquid and gas hydrocarbon formation. The HI index and H/C values favor significant quality of hydrocarbon (gas and oil) potential. [ABSTRACT FROM AUTHOR]

Coal seams preserve high‐resolution records of ancient terrestrial water table (base level) fluctuations in ancient peat accumulations, but little is known about base level change in anomalously thick coal seams. Using the Early Cretaceous 91 m anomalously thick No. 6 coal (lignite) seam in the Erlian Basin (north‐east China) as a case study, the origin and evolution of peat accumulation in a continental faulted basin is revealed by sedimentological, sequence stratigraphic and coal petrological analyses. The lignite is dominated by huminite, indicating oxygen‐deficient and waterlogged conditions in the precursor mire. Four types of key sequence stratigraphic surfaces are recognized, including paludification, terrestrialization, accommodation‐reversal and give‐up transgressive surfaces. Vertically, the No. 6 coal seam consists of fourteen superimposed wetting‐up and drying‐up cycles separated by key sequence stratigraphic surfaces, with each of these cycles having a mean duration of about 156 to 173 kyr. In a high accommodation peat swamp system, the wetting‐up cycles are generally characterized by an upward increase in mineral matter and inertodetrinite and an upward decrease in huminite with the paludification surface as their base and the give‐up transgressive surface or accommodation‐reversal surface as their top, representing a trend of upward‐increasing accommodation. In contrast, the drying‐up cycles are generally characterized by an upward decrease in mineral matter and inertodetrinite and an upward increase in huminite, with the terrestrialization surface as their base and the accommodation‐reversal surface as their top, representing a trend of upward‐decreasing accommodation. A multi‐phase mire stacking model for accumulation of the coal seam is proposed based on high‐frequency accommodation cycles and the stratigraphic relationships between coal and clastic sediments. High‐frequency accommodation cycles in the coal are closely related to water table fluctuations in the precursor mires and are driven by high‐frequency climate via changes in the intensity and seasonality of precipitation in a relatively stable subsidence regime. Recognition that the No. 6 coal seam is composed of multiple stacked mires has implications for studies addressing palaeoclimatic inferences and genesis of anomalously thick coals seams. [ABSTRACT FROM AUTHOR]

The Eocene coal deposits of west Daranggiri coalfield of Meghalaya is hosted in the Tura Formation. The coals are perhydrous in composition, rich in organic matters and poor in mineral content. The organic matters are dominantly represented by Type III kerogens contributed by terrestrial plants. Petrographic analysis confirms dominance of vitrinite with subordinate amounts of liptinite and inertinite. Maturity parameters like vitrinite reflectance, Rock-Eval Tmax, volatile matter content etc. indicate low thermal maturity of the coal within lignite to subbituminous rank. The coals are immature to act as petroleum source rock despite having high-quality organic matters. However, perhydrous nature of the organic matters and significant amount of liptinite macerals suggest that despite low thermal maturity, the coals might have some capacity to generate liquid hydrocarbon. High liptinite and perhydrous vitrinite contents of the coal may result in suppression of vitrinite reflectance, thus, underestimation of maturity. Presence of exsudatinite in the coal also points to generation of some liquid hydrocarbon. The coal deposits possess excellent potential for hydrogenation industry. The coals are characterized by very high rate of conversion from coal to oil and high oil yield. Indices of facies critical maceral association indicate the origin of the coal in wet swamps under mildly oxic to the anoxic environment with moist hydrodynamic condition. The high sulphur content of the coal, association of marine palynological assemblage and presence of limestone beds at the top of the Tura Formation point to nearshore environment of deposition. [ABSTRACT FROM AUTHOR]

Inertinite, a maceral group, which remains inert or partly fuses during the carbonization process, plays a vital role in coke making. During carbonization, vitrinite softens and resolidifies to form porous mosaic texture and loses its original identity whereas, inertinite gets filled up as filler form firmly implanted within different types of mosaic matrix. Their size and association with other maceral or minerals also modify their behavior in coke. Structured and unstructured, smaller and larger, high and low reflectance, oxidation or heat alteration, all behaves in a different manner. The Gondwana coals are characteristically rich in inertinite group of macerals, especially semifusinite which has a wide range of reflectance and morphology varying from vitrinite to fusinite. Present study deals with the behavior of inertinite in Gondwana coals during the carbonization process. Coke petrography is an important tool which gives an insight into the maceral interaction. Different macerals of the inertinite group have been analyzed in coke and compared with their occurrence in parent coal. The study reveals the influence of different inertinite macerals in determining the coke quality. [ABSTRACT FROM AUTHOR]

Analysis of coal-bearing strata in the Paleocene Firkanten Formation in the Central Tertiary Basin of Spitsbergen (Svalbard) has shown that deposition was in a coastal plain setting. Interpretation of numerous cores indicates that deposition occurred in coastal plain mires, lagoons, tidal inlets, barrier bars and shoreface environments. These form a series of shallowing-up successions metres to tens of metres thick. Correlation between boreholes over distances in excess of 100 km proved challenging with no regional marker horizons. However, by constructing paleogeographic maps as part of the process of correlating, and by using analogous modern coastal areas as indicators of facies belt widths, a correlation scheme that provides patterns of facies distribution that are consistent in three dimensions has been created. The resulting stratigraphic framework comprises parasequences grouped into parasequence sets that show an overall retrogradational pattern representing a stepwise transgression over a basin floor that was subsiding due to flexural subsidence. Absence of incision or other evidence for relative sea-level fall within the whole succession suggests that flexural subsidence was sufficient to keep pace with eustatic sea-level falls. The basal unconformity surface is overlain by a poorly sorted deposit of reworked regolith that forms a strongly diachronous unit, occurring at the base of successive parasequences. Individual parasequences formed in response to relative sea-level rises that are considered likely to be eustatic in origin and resulted in flooding of the coastal plain. Centimetre-scale analysis of the coal maceral distribution through the thickness of the lowermost major coal seam indicates that there were also higher-frequency fluctuations of relative sea level, possibly at Milankovitch-scale, during the deposition of individual parasequences. This new facies model and interpretation of the subsidence history of the basin provides a framework for understanding the distribution of sediments within a coal-bearing coastal plain succession. [ABSTRACT FROM AUTHOR]

Copyright of Natural Gas Geoscience is the property of Natural Gas Geoscience and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Natural Gas Geoscience is the property of Natural Gas Geoscience and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Considering the heterogeneous nature and non-stationary property of inertinite components, we propose a texture description method with a set of multifractal descriptors to identify different macerals with few but effective features. This method is based on the multifractal spectrum calculated from the method of multifractal detrended fluctuation analysis (MF-DFA). Additionally, microscopic images of inertinite macerals were analyzed, which were verified to possess the property of multifractal. Simultaneously, we made an attempt to assess the influences of noise and blur on multifractal descriptors; the multifractal analysis was proven to be robust and immune to image quality. Finally, a classification model with a support vector machine (SVM) was built to distinguish different inertinite macerals from microscopic images of coal. The performance evaluation proves that the proposed descriptors based on multifractal spectrum can be successfully applied in the classification of inertinite macerals. The average classification precision can reach 95.33%, higher than that of description method with gray level co-occurrence matrix (GLCM; about 7.99%). [ABSTRACT FROM AUTHOR]

This study aims to compare iso-rank vitrinite-rich and inertinite-rich coal samples to understand the impact of coal-forming processes on pyrolysis chemistry. A medium rank C bituminous coal was density-fractionated to create a vitrinite-rich and an inertinite-rich sub-sample. The vitrinite-rich sample has 83 vol% total vitrinite (mineral-matter-free basis), whereas the inertinite-rich counterpart has 66 vol% total inertinite. The vitrinite-rich sample is dominated by collotelinite and collodetrinite. Fusinite, semifusinite, and inertodetrinite are the main macerals of the inertinite-rich sample. Molecular chemistry was assessed using a pyrolysis gas chromatograph (py-GC) equipped with a thermal desorption unit coupled to a time of flight mass spectrometer (MS) (py-GC/MS) and solid-state nuclear magnetic resonance (13C CP-MAS SS NMR). The pyrolysis products of the coal samples are generally similar, comprised of low and high molecular weight alkanes, alkylbenzenes, alkylphenols, and alkyl-subtituted polycyclic aromatic hydrocarbons, although the vitrinite-rich sample is chemically more diverse. The lack of diversity exhibited by the inertinite-rich sample upon pyrolysis may be interpreted to suggest that major components were heated in their geologic history. Based on the 13C CP-MAS SS NMR analysis, the inertinite-rich sample has a greater fraction of phenolics, reflected in the py-GC/MS results as substituted and unsubstituted derivatives. The greater abundance of phenolics for the inertinite-rich sample may suggest a fire-related origin for the dominant macerals of this sample. The C2-alkylbenzene isomers (p-xylene and o-xylene) were detected in the pyrolysis products for the vitrinite-rich and inertinite-rich samples, though more abundant in the former. The presence of these in both samples likely reflects common source vegetation for the dominant vitrinite and inertinite macerals. [ABSTRACT FROM AUTHOR]

The pore structure of coal reservoirs is the main factor influencing the adsorption–diffusion rates of coalbed methane. Mercury intrusion porosimetry (MIP), low-pressure nitrogen adsorption (LP-NA), low-pressure carbon dioxide adsorption (LP-CA), and isothermal adsorption experiments with different macerals were performed to characterize the comprehensive pore distribution and methane adsorption–diffusion of coal. On the basis of the fractal theory, the pore structures determined through MIP and LP-NA can be combined at a pore diameter of 100 nm to achieve a comprehensive pore structural splicing of MIP, LP-NA, and LP-CA. Macro–mesopores and micro-transitional pores had average fractal dimensions of 2.48 and 2.18, respectively. The Langmuir volume (VL) and effective diffusion coefficients (De) varied from 31.55 to 38.63 cm3/g and from 1.42 to 2.88 × 10−5 s−1, respectively. The study results showed that for super-micropores, a higher vitrinite content led to a larger specific surface area (SSA) and stronger adsorption capacity but also to a weaker diffusion capacity. The larger the average pore diameter (APD) of micro-transitional pores, the stronger the diffusion capacity. The diffusion capacity may be controlled by the APD of micro-transitional pores. [ABSTRACT FROM AUTHOR]

• The coal-based graphene was prepared from the macerals separated from coal. • Vitrinite, inertinite, cutinite, barkinite and their coal-based graphene products were compared in structure. • The influence of coal rank and macerals on the preparation of coal-based graphene was discussed. Graphene is prepared using the improved Hummers redox method to study the preparation and structural characteristics of coal-based graphene from coal macerals of rank between 0.52 % and 1.98 %. The macerals are separated and enriched by hand sorting, sieving, and isopyknic gradient centrifugation. The crystal characteristics of the macerals, coal-based graphite, and graphene are characterized by XRD, Raman, SEM and TEM. The flake graphene with stable structure, good extensibility, different cell parameters and defects can be prepared from macerals. All the preparation yields are less than 4.0 %. The XRD data shows that after high-temperature graphitization, the layer spacing d 002 of each sample is less than 0.3400 nm, and the lamellar crystallite sizes L a and L c are 7.70–21.09 nm and 11.53–16.94 nm, respectively. After the redox reaction, inertinite MLI-GS, YCWI-GS, and vitrinite GMDV-GS have the layer spacing d 002 , lamellar extendability L a , stacking thickness L c , and average stacking layer N ave that tend to be graphite-like structure. The microcrystalline structure is well developed and stable. Raman also confirmes that inertinite and high-rank vitrinite-derived graphene have fewer structural defects, good ordering, and a high degree of graphitization. The average values of I D /I G and A D /A G of maceral → coal-based graphite → graphene are 0.73 → 0.29 → 1.06, 2.12 → 0.40 → 1.62, indicating a relationship between the structural order: coal-based graphite > maceral > graphene, and between the degree of graphitization: coal-based graphite > graphene > maceral. The SEM and TEM dates show that inertinite tends to form a flat graphene structure with four–six layers, and has good light transmission. The graphene has few folds and warps, good layer extensibility, and high lattice order. The layer spacing at the edge is consistent with the d 002 of XRD analysis. Vitrinite, cutinite, and barkinite derived graphene are similar to a kneaded paper balls. The layers are mixed with each other, forming more folds and ripples, and the peeling effect is poor. Only the high-rank GMDV-GS is clean like gauzy graphene, indicating that the micromorphological characteristics of graphene are related to the coal rank and macerals. [ABSTRACT FROM AUTHOR]

• Residual carbon formation from entrained-flow gasification fine slag was revealed. • Vitrinite is prone to achieve a higher conversion level at entrained-flow conditions. • Vitrinite residual carbon has more active sites, giving a higher gasification activity. The high carbon content and poor combustibility of the fine slag produced by the entrained – flow gasification limits its resource utilization. From coal chemistry, residual carbon formation is highly related to the coal macerals. In this study, Meihuajing coal was selected to be separated and enriched macerals by density gradient centrifugation. Different macerals were gasified at 1300 °C and H 2 O/O 2 conditions in the drop tube furnace to collect residual carbon. The results showed that the area shrinkage of inertinite grew to 0.90 at the early stage, but final conversion required a longer induction period to realize. The residual carbon of vitrinite had richer pore structure and larger specific surface area as well as lower degree of aromatization and graphitization than inertinite, resulting in higher reactivity. The present study is important in understanding the relationship between the formation of residual carbon and the structure of coal macerals. [ABSTRACT FROM AUTHOR]

The Devonian–Mississippian (D–M) black shales of the Bakken Formation are of interest as a hydrocarbon source due to their high total organic carbon (TOC; 2.2–17.4%) content. The Upper and Lower Members of the Bakken Fm. are shallow marine (100–150 m) sequences. Thirty samples were selected for maceral identification, kerogen typing, and solid bitumen reflectance (SBR o) based on TOC content and down-core spacing. The shales contain alginite, bituminite, abundant solid bitumen (SB), and minor amounts of inertinite. Solid bitumen increases in quantity with increasing thermal maturity. Pyrolysis (85 samples) provided S1 (avg. 8.0 mg HC/g rock), S2 (avg. 24.3 mg HC/g rock), hydrogen index (HI; avg. 201 mg HC/g TOC), oxygen index (OI; avg. 7 mg CO 2 /g TOC), and R o (0.60–1.03%) calculated from T max. Plots of HI vs. OI and HI vs. T max (°C) were used to assess kerogen type but are not consistently in agreement with the petrographic assessment. Some samples from more thermally mature cores plot as Type III (vitrinite) kerogen instead of Type II (alginite and bituminite) kerogen, the latter confirmed through petrographic observations of lower maturation samples. This is largely due to increased SB in more thermally mature samples (R o = 0.83–1.03%), as SB is known to have a lower HI content than Type II kerogen. Petrographic data show more alginite and bituminite (19–55%) in the thermally less mature samples (R o = 0.60–0.83%) compared to more dispersed SB (67–86%) and less alginite and bituminite (<1%) in the more thermally mature samples (R o = 0.89–1.01%). Early research on the Bakken Fm. reported lower than expected vitrinite reflectance values and attributed them to vitrinite "suppression". The scarcity of vitrinite and abundance of SB suggest that early work likely reported reflectance on SB. Recent attempts to assess the thermal maturity of the Bakken black shales have converted SBR o to vitrinite reflectance equivalence (V RE). However, there are multiple SB populations present in these shales and it is not always clear which SB populations were included, possibly contributing to error. In the current study, only smooth, homogenous SB was measured (0.68–1.14% SBR o) and V RE values calculated (0.54–1.49%) to assess thermal maturity from the basin margin to the depocenter; inclusion of measurements on granular, heterogeneous SB (14–21 vol%), which are ∼53% lower than those for smooth, homogenous SB (3–12 vol%), results in lower mean reflectances, especially in more mature samples. Vitrinite reflectance equivalent data calculated using the D–M New Albany Shale equation of Liu et al. (2019) agrees with liptinite fluorescence and Rock-Eval R o , whereas V RE based on the D–M Woodford Shale equation of Cardott and Comer (2021) does not. This suggests the importance of applying V RE equations from similar formations both in terms of thermal history, as well as kerogen type and age. Results from SBR o , Rock-Eval R o , V RE , and observations of alginite fluorescence indicate that samples from the current study range from the early oil window into the condensate, wet gas zone. • Bakken Shale contains multiple solid bitumen populations but scarce vitrinite. • Alginite and bituminite decrease while solid bitumen increases at higher maturity. • New Albany Shale V RE equations work better than one from the Woodford Shale. • Combining V RE , fluorescence, and Rock-Eval data provides more accurate maturity. • Increases in solid bitumen affect Rock-Eval kerogen typing. [ABSTRACT FROM AUTHOR]

• In-situ abrasion resistance of cokes was examined at elevated temperatures. • Tests were carried out in a controlled gas atmosphere (reactive (CO 2) or inert). • Abrasion resistance decreased with increase in temperature, even at 400 °C. • Difference between room and high temperature test results depended on parent coals. • Wear severity was quantified using a combination of image analysis techniques. A novel approach was developed to examine coke abrasion resistance in-situ at temperatures of up to 950 °C and in a controlled gas atmosphere using rotational tribological testing. The originality of this approach lay in the ability to apply tribological testing to the porous coke surface at elevated temperatures under a controlled inert or CO 2 reactive atmosphere. Coke wear characteristics were quantified via (i) the application of advanced microscopy and image analysis techniques, and (ii) analysis of the coefficient of friction (COF) during tribological testing. Two pilot oven cokes were examined in this study, which were generated from single coking coals of similar rank but different petrographic composition. The cokes tested showed a deterioration in abrasion resistance even at 400 °C, and this was accentuated at 950 °C. The COF and the severity of the wear as a function of temperature and gas atmosphere were markedly different between the two cokes. Coke C396 from a mid-to-low vol, medium vitrinite coal showed no statistically significant differences between the wear severity results recorded following room temperature testing and high temperature testing in a CO 2 environment. Conversely, the more reactive coke C426 with a higher parent coal inertinite content showed clear differences in the extent of abrasive wear at room temperature and at high temperature in both inert and reactive gas atmospheres. This suggests that the reduction in abrasion resistance at elevated temperatures is accentuated in the coke with the highest coke reactivity index (CRI) and the highest content of inertinite maceral derived components (IMDC). Our research has shown that at room temperature, the IMDC show greater resistance to abrasion than the reactive maceral derived components (RMDC). This has implications for understanding the relevance of room temperature testing to the abrasion resistance of coke under practical blast furnace operation conditions. For example, a coke from a coal or blend with a comparatively high inertinite content may show lower resistance to abrasion in the blast furnace than would be expected from tumble drum indices. Larger sample numbers and cokes from a variety of single coals need to be tested in further work to verify these assertions. Finally, a novel method using micro-CT image analysis was developed to examine the wear path generated at the coke surface during tribological testing. The purpose of this was to assess the extent of the abrasive wear by comparing the rendered micro-CT images before and after tribological testing. A colour gradient scale was used to facilitate the quantitative assessment, whereby the colour of each voxel was based on the distance from the nearest voxel that is associated with solid phase. As expected, the specific surface area (SSA) calculated for the upper 1 mm of each sample decreased following tribological testing due to the generation of a wear track which is smoother than the initially rough, porous coke surface. In the C426 coke type examined, the SSA decreased the most for the sample tested in an argon atmosphere at 950 °C, matching the COF and quantified wear severity results, which showed there was a notable increase in abrasive wear to this coke as the temperature was raised from room to elevated temperature. Coupling this method of analysis with 3D visualisation techniques in further work would provide a powerful approach to examine and quantify mechanisms of coke surface breakage and the microstructural and/or microtextural features responsible for the breakage. [ABSTRACT FROM AUTHOR]

The natural removal of carbon dioxide and its permanent storage by the Earth system occurs through (i) inorganic carbon and (ii) organic carbon pathways. The former involves the "mineralization" of carbon and formation of carbonate minerals, whereas the latter employs the "maceralization" or natural carbonization of biomass into the "inertinite maceral". The production of biochar is a carbon dioxide removal (CDR) method that imitates the geological organic carbon pathway, using controlled pyrolysis to rapidly carbonize and transform biomass into inertinite maceral for permanent storage. Therefore, the main challenge in assessing biochar's permanence is to ensure complete transformation has been achieved. Inertinite is the most stable maceral in the Earth's crust and is hence considered an ultimate benchmark of organic carbon permanence in the environment. Therefore, this study aims to measure the degree of biochar's carbonization with respect to the well-established compositional and microscopic characteristics of the inertinite. The random reflectance (R o) of 2% is proposed as the "inertinite benchmark" (IBR o 2%) and applied to quantify the permanent pool of carbon in a biochar using the R o frequency distribution histogram. The result shows that 76% of the studied commercial biochar samples have their entire R o distribution range well above IBR o 2% and are considered pure inertinite biochar. The oxidation kinetic reaction model for a typical inertinite biochar indicates a time frame of approximately 100 million years for the degradation and loss of half of the carbon in the biochar. This estimate assumes exposure to a highly oxidizing environment with a constant surface temperature of 30°C, highlighting the inherent "permanent" nature of the material. In a less hostile environment, the expected permanence of inertinite is generally anticipated to be even longer. In addition to the inertinite that constitutes the largest fraction of the typical commercial biochar, an incompletely carbonized biochar may contain up to three other organic pools in descending order of stability. The relative concentration of these pools in a biochar can be quantified by a combination of geochemical pyrolysis and random reflectance methods. Furthermore, the R o can be used to calculate the carbonization temperature (CT oC) of a biochar, which is the maximum temperature to which biochar fragments have been exposed during pyrolysis. This indicator provides important information about the efficiency of the carbonization process and subsequently the biochar's stability, with respect to production temperature (PT oC), heating residence time, and thermal diffusivity. The Earth's carbon dioxide removal and storage occur via inorganic and organic pathways: mineralization and maceralization. Biochar, imitating the organic pathway, undergoes controlled pyrolysis to transform biomass feedstock through a carbonization process into the inertinite maceral, which is a permanently stable form of organic carbon. Kinetic modeling in this study confirms inertinite's carbon stability over geological time scale. Assessing biochar's permanence hence hinges on achieving complete carbonization and transformation. Inertinite serves as the gold standard for organic carbon permanence, guiding this study to measure biochar's carbonization against inertinite characteristics. Analyzing the random reflectance (R o) of biochar reveals that 76% of studied samples qualify as pure inertinite. Apart from inertinite, other organic pools in biochar, quantifiable through geochemical pyrolysis and R o methods, affect stability. Determining the carbonization temperature offers insights into biochar's efficiency and stability concerning production variables. • Earth's CO 2 storage: inorganic & organic pathways - mineralization and maceralization. • Biochar: mimics organic pathway, transforms biomass to the permanently stable inertinite. • Inertinite benchmark: measures biochar's carbonization degree for permanence assessment. • Study shows 76% commercial biochar as pure inertinite, exceeding benchmark. • R o analysis: reveals carbon pools, calculates carbonization temperature for biochar stability. [ABSTRACT FROM AUTHOR]

Abstract Lignite samples collected from Vastan, Rajpardi and Tadkeshwar lignite mines of Cambay basin (Gujarat) were subjected to organic petrographic investigations and geochemical analyses and the data, thus generated, is used to reconstruct the paleodepositional history of these lignite sequences. The lignites of Cambay basin dominantly comprise huminite maceral group (71.6%–86.3%) followed by liptinite (10.1%–19.3%) and inertinite (3.6%–11.0%) maceral groups. The mineral matter varies from 9.0% to 20.0%. The petrography based facies model indicates that these lignites have high values of gelification index (GI) and low tissue preservation index revealing a continuous wet condition in the basin and a relatively slower rate of subsidence during the decay of organic matter. On several occasions, during the formation of seams in Tadkeshwar, Rajpardi and Vastan mines, the value of GI exceeded 10 which indicates a forest permanently flooded and the cause of pronounced degree of degradation. However, few sections in Tadkeshwar seam had relatively drier spells of environmental conditions due to fluctuation in the water table as revealed by moderately high content of inertinite macerals. This is specially indicated by the occurrence of funginite which normally thrives in the upper oxygenated peatigenic layer and indicates prevalence of oxic conditions during plant deposition. Such conditions prevailed during a transgressive phase but there were intermittent fluvial activities also giving rise to supratidal flood plain as reflected in the form of associated carbonaceous shales in the basin.

The Madzaringwe Formation in the Vele colliery is one of the coal-bearing Late Palaeozoic units of the Karoo Supergroup, consisting of shale with thin coal seams and sandstones. Maceral group analysis was conducted on seven representative coal samples collected from three existing boreholes—OV125149, OV125156, and OV125160—in the Vele colliery to determine the coal rank and other intrinsic characteristics of the coal. The petrographic characterization revealed that vitrinite is the dominant maceral group in the coals, representing up to 81–92 vol.% (mmf) of the total sample. Collotellinite is the dominant vitrinite maceral, with a total count varying between 52.4 vol.% (mmf) and 74.9 vol.% (mmf), followed by corpogelinite, collodetrinite, tellinite, and pseudovitrinite with a count ranging between 0.8 and 19.4 vol.% (mmf), 1.5 and 17.5 vol.% (mmf), 0.8 and 6.5 vol.% (mmf) and 0.3 and 5.9 vol.% (mmf), respectively. The dominance of collotellinite gives a clear indication that the coals are derived from the parenchymatous and woody tissues of roots, stems, and leaves. The mean random vitrinite reflectance values range between 0.75% and 0.76%, placing the coals in the medium rank category (also known as the high volatile bituminous coal) based on the Coal Classification of the Economic Commission for Europe (UN-ECE) coal classification scheme. The inertinite content is low, ranging between 4 and 16 vol.% (mmf), and it is dominated by fusinite with count of about 1–7 vol.% (mmf). The high amount of inertinite, especially fusinite, with empty cells and semi-fusinite in the coals will pose a threat to coal mining because it aids the formation of dust.

This paper studied the macerals enrichment of the low-rank coal which produced by Shigetai Coal Mine, Shenhua Group. The coal sample fed to the Falcon were the product of the rod mill after 10 minutes grinding. Three factors were carried out, rotational frequency, feed rate and water pressure. The orthogonal experiment was designed to investigate the interaction between the three factors and a model was established between the factors and response values. Taking the vitrinite recovery rate as the response value, there was an interaction between the rotational frequency and the water pressure, moreover, the effect of the rotational frequency on the vitrinite recovery rate was greater than the water pressure, while, the feed rate on the vitrinite recovery rate was not significant. Taking the vitrinite enrichment ratio as the evaluation index, the Quadratic model was recommended, there was an interaction between the rotational frequency and the feed rate, moreover, the rotational frequency had better response to the vitrinite enrichment ratio than the water pressure and the feed rate. In order to optimize the experimental conditions, and the vitrinite enrichment ratio was set to 1.2, the vitrinite recovery rate was the larger the better, the optimal separation conditions obtained were the rotational frequency 30Hz, the water pressure 0.03MPa, and the feed rate 15ml/s in the laboratory. [ABSTRACT FROM AUTHOR]

Jurassic and Triassic coals and organic matter-rich shales of the Tabas Basin, Iran, were investigated with respect to their thermal maturation and petrographic composition. The Triassic coals of the Parvadeh coal field range in vitrinite reflectance between 1.17% and 1.37% and the Jurassic coals of the Mazino coal field between 2.08% and 2.29% VRr. Maceral analysis revealed a predominance of vitrinite in all samples, with slightly higher percentages of inertinite in the Jurassic samples. Rock–Eval analyses confirm the presence of type III kerogen in the Triassic coals, while the Jurassic coals contain strongly carbonized residual kerogen. The range of sulfur contents for coals from the Parvadeh coal field (0.37% to 4.64%) and Mazino coal field (0.45% to 2.92%) is related to the effect of marine water in peat. The studied samples are characterized by the predominance of short- over long-chained n-alkanes. The relatively high Pr/Ph ratios indicate predominance of terrestrial organic matter whereas Pr/n-C17 and Ph/n-C18 ratios prove oxic conditions during deposition. In addition, the DBT/Phen ratio shows that these coals formed in fluvial/deltaic environments. Molecular geochemical parameters such as carbon preference index (CPI, 0.99–1.04), methyl phenanthrene index (MPI, 1.20–1.60), methyl naphthalene ratio (MNR, 1.61–3.45), and ethyl naphthalene ratio (ENR, 4–6.78) confirm the high maturity of the samples. Burial and thermal history reconstruction indicates necessity of an erosional thickness of about 4000 m in the Parvadeh area. Towards the Mazino area, a higher basal heat flow up to 80 mW m−2 is assumed for the Paleogene leading to higher maturities. [ABSTRACT FROM AUTHOR]

Copyright of Natural Gas Geoscience is the property of Natural Gas Geoscience and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Featured Application: Maceral Analysis; Coal Processing. An intelligent analytical technique which is able to accurately identify maceral components is highly desired in the fields of mining and geology. However, currently available methods based on fixed-size window neglect the shape information, and thus do not work in identifying maceral composition from one entire photomicrograph. To address these concerns, we propose a novel Maceral Identification strategy based on image Segmentation and Classification (MISC). Considering the complex and heterogeneous nature of coal, a two-level coarse-to-fine clustering method based on K-means is employed to divide microscopic images into a sequence of regions with similar attributes (i.e., binder, vitrinite, liptinite and inertinite). Furthermore, comprehensive features along with random forest are utilized to automatically classify binder and seven types of maceral components, including vitrinite, fusinite, semifusinite, cutinite, sporinite, inertodetrinite and micrinite. Evaluations on 39 microscopic images show that the proposed method achieves the state-of-the-art accuracy of 90.44% and serves as the baseline for future research on maceral analysis. In addition, to support the decisions of petrologists during maceral analysis, we developed a standalone software, which is freely available at https:/github.com/GuyooGu/MISC-Master. [ABSTRACT FROM AUTHOR]

The article presents the results of the petrographic analysis of the lignite from Turów deposit and the residues formed during its ex-situ gasification. The analysis used seven spot samples, representing different transformation areas, collected from the residues. The obtained results, compared with the lignite before the gasification, have shown that changes in the petrographic composition correspond to the temperature distribution during the process. The highest amounts of gasified particles, represented by inertoid-type chars, were observed in samples collected from areas where the temperature exceeded 600°C. The unchanged lignite macerals dominated in samples from areas where the temperature was below 200°C. [ABSTRACT FROM AUTHOR]

This study is to assesses the depositional environment and characteristics of petroleum source rocks of Mae Teep basin in Lampang province, Thailand. The stratigraphic units included leonardite, coals, and oil shale units. A total of 44 samples were collected and subjected to petrological analysis for their maceral types. Additionally, the proximate and ultimate chemical analyses were performed. All results were used to interpret their deposition environments. The leonardite contains a high concentration of ash but low concentrations of organic matters, <15.00 wt%. The coal sub-units contain 10.40-68.48 wt% ash, 27.43-45.78 wt% volatile matter, and 3.16-46.31 wt%fixed carbon. The coals are classified as vitrinite (67.4-75.3%) and liptinite (11.9-23.2%). The liptinite is dominated by liptodetrinite, sporinite, cutinite, and fluorinite. The oil shale contains 49.59-83.85 wt% ash, 14.55-37.67 wt% volatile matter, and 0.55-12.74 wt% fixed carbon and short- and long-bodied lamalginite maceral dominated. The results indicated that fluctuation of the water levels had caused the depositional environment changes from a shallow swamp to reed-sedge peat, and from forest swamp to deep, stagnant, lacustrine deposits. The organic deposits settled in the basin through catastrophic fluvial flood events. [ABSTRACT FROM AUTHOR]

The article discusses the impact of the lithotype of lignite on the suitability for gasification in CO2 atmosphere. The research was aimed at determining the influence of lithotype, petrographic composition, and physical and chemical properties of coal on the composition and release of syngas. The examined coals were humic coals. The first step was to determine the impact of lithotype on the degree of carbon conversion at a temperature of up to 815 °C. The gasification process was conducted in the temperature range of 600–1100 °C. During the experiment, two gas samples, used for determining the chemical content of gas, were collected at 950 and 1050 °C, respectively. What is more, continuous monitoring of the gas density during the gasification was carried out. Depending on the lithotype, the content of ash, moisture, and the degree of coalification, the intensity of gas release is different for different temperatures. In addition, it has been found that coals with a high content of poorly gelified xylite and a low ash content are the fastest reacting and the most responsive. The importance of this research lies in determining that the gasification of coal with a low degree of coalification requires technologies carried out at reactor temperatures above 1000 °C. [ABSTRACT FROM AUTHOR]

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Abstract Three maceral samples with vitrinite content of 88, 77 and 66 vol% (mmf) obtained from an Australian coking coal were investigated to understand the difference in their thermoplastic development. Each sample was packed in a quartz tube and heated from the bottom by a heating plate of which temperature was set to slowly ramp from room temperature to 900 °C. A thermocouple was inserted at 55 mm from the base to monitor the temperature change at this position as heat transferred through via thermal conduction. At the end of the experiment, the thermocouple measured temperatures at 469, 485 and 495 °C for the three respective maceral samples, suggesting a greater thermal gradient existed in samples with higher vitrinite concentration. The heated samples were then analysed by laser desorption/ionization time of flight imaging mass spectrometry (LDI-TOF-IMS) to track the change in molecular weight distribution across the sample length. Significant intensity of ionisable species was recorded in regions close to the thermocouple position for all maceral samples. Samples with higher vitrinite content displayed a greater molecular weight discrepancy (∆ m / z) in the plastic region compared to that in samples with lower vitrinite content, indicating a larger molecular variation occurred in these samples. Highlights • Larger thermal gradient existed in maceral samples contained higher vitrinite content • Significant signal intensity recorded in the plastic and resolidification regions • A wider change recorded in peak molecules of vitrinite-rich samples suggesting more vigorous chemical changes occured [ABSTRACT FROM AUTHOR]

Copyright of Scientific Bulletin of National Mining University is the property of National Mining University, State Higher Educational Institution and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)