Petro-chemical investigation of some perhydrous Indian coals

An attempt has been made to study the petro-chemical characteristics of some high sulphur sub-bituminous coal samples from Makum coalfield, Assam, India. The proximate and ultimate analyes were carried out and forms of sulphur were determined and their relationships with the Maceral constituents (vitrinite, liptinite, and inertinite) were investigated. The macerals (vitrinite+liptinite+inertinite) have significant relationships (R²>0.500) with volatile matter and carbon, whereas weak correlations were seen with rest of the physico-chemical characteristics of the coals. The study reveals that these coals are rich in vitrinites and sulphur and are aromatic in nature. These coals have good hydrocarbon potential.     

Study of petrological characteristics of coal deposits from Marki-Jhari-Jamni area, Wardha valley coalfield, Maharashtra

A detailed study of maceral composition and vitrinite reflectance of the coal deposits from Marki-Jhari-Jamni area, situated in the northwestern extremity of Wardha valley coalfield, Yeotmal district, Maharashtra has been carried out with special reference to their depositional set up. These coals have two distinct types of maceral organization, one having significantly high distribution of the vitrinite group of macerals (35–41%) and the other containing the dominance of inertinite (26–49%). Liptinite maceral group is recorded between 14 and 24%, barring a few coal bands having liptinite maceral group as high as 33–37%. The vitrinite reflectivity ranges from 0.38–0.43%. Thus, they have attained sub-bituminous C rank. Mineral matter in these coals varies between 15 and 22%. The present study suggests that the basin primarily experienced cold climate having intermittent brackish water influx with alternating dry oxidizing spells.     

Study of petrological characteristics of coal deposits from Marki-Jhari-Jamni area,Wardha valley coalfield,Maharashtra

A detailed study of maceral composition and vitrinite reflectance of the coal deposits from Marki-Jhari-Jamni area, situated in the northwestern extremity of Wardha valley coalfield, Yeotmal district, Maharashtra has been carried out with special reference to their depositional set up. These coals have two distinct types of maceral organization, one having significantly high distribution of the vitrinite group of macerals (35–41%) and the other containing the dominance of inertinite (26–49%). Liptinite maceral group is recorded between 14 and 24%, barring a few coal bands having liptinite maceral group as high as 33–37%. The vitrinite reflectivity ranges from 0.38–0.43%. Thus, they have attained sub-bituminous C rank. Mineral matter in these coals varies between 15 and 22%. The present study suggests that the basin primarily experienced cold climate having intermittent brackish water influx with alternating dry oxidizing spells.     

Methane and carbon dioxide sorption on a set of coals from India

Complete sorption isotherm characteristics of methane and CO₂ were studied on fourteen sub-bituminous to high-volatile bituminous Indian Gondwana coals. The mean vitrinite reflectance values of the coal samples are within the range of 0.64% to 1.30% with varying maceral composition. All isotherms were conducted at 30 °C on dry, powdered coal samples up to a maximum experimental pressure of ~ 7.8 MPa and 5.8 MPa for methane and CO₂, respectively.The nature of the isotherms varied widely within the experimental pressure range with some of the samples remained under-saturated while the others attained saturation. The CO₂ to methane adsorption ratios decreased with the increase in experimental pressure and the overall variation was between 4:1 and 1.5:1 for most of the coals. For both methane and CO₂, the lower-ranked coal samples generally exhibited higher sorption affinity compared to the higher-ranked coals. However, sorption capacity indicates a U-shaped trend with rank. Significant hysteresis was observed between the ad/desorption isotherms for CO₂. However, with methane, hysteresis was either absent or insignificant. It was also observed that the coal maceral compositions had a significant impact on the sorption capacities for both methane and CO₂. Coals with higher vitrinite contents showed higher capacities while internite content indicated a negative impact on the sorption capacity.     

Petrological evolution of the Paleogene coal deposits of Jammu, Jammu and Kashmir, India

A detailed macro- and micro-petrological investigation of 8 coal seam profiles of Eocene age from the sub-Himalayan zone of Jammu was undertaken in order to characterize them petrographically and to focus on their evolution. The quantitative data suggest that these coals are vitrinite rich, with low concentrations of inertinite and rare occurrences of liptinite. According to microlithotype concentration these coals may be characterized as vitrinite rich, with minor amounts of clarite, vitrinertite and trimacerite. The dominant minerals are clays, siderite and pyrite (occurring mostly as disseminations, cavity filling and in framboidal state). These coals are vitric in type, low volatile bituminous in rank and ashy in grade.The petrographic character and the presence of teleutospores suggest that, similar to other Tertiary coal deposits in the world, the angiosperm flora contributed chiefly to the development of coal facies in the area. The maceral and microlithotype composition shows that these coals originated from the low forest and undisturbed (in situ) peat in foreland basins under limno-telmatic depositional conditions. The water was brackish with regular influxes of fresh water.     

Properties of thermally metamorphosed coal from Tanjung Enim Area, South Sumatra Basin, Indonesia with special reference to the coalification path of macerals

Thermally metamorphosed Tertiary age coals from Tanjung Enim in South Sumatra Basin have been investigated by means of petrographic, mineralogical and chemical analyses. These coals were influenced by heat from an andesitic igneous intrusion. The original coal outside the metamorphosed zone is characterized by high moisture content (4.13–11.25 wt.%) and volatile matter content (> 40 wt.%, daf), as well as less than 80 wt.% (daf) carbon and low vitrinite reflectance (VR_max = 0.52–0.76%). Those coals are of subbituminous and high volatile bituminous rank. In contrast the thermally metamorphosed coals are of medium-volatile bituminous to meta-anthracite rank and characterized by low moisture content (only < 3 wt.%) and volatile matter content (< 24 wt.%, daf), as well as high carbon content (> 80 wt.%, daf) and vitrinite reflectance (VR_max = 1.87–6.20%). All the studied coals have a low mineral matter content, except for those which are highly metamorphosed, due to the formation of new minerals.The coalification path of each maceral shows that vitrinite, liptinite and inertinite reflectance converge in a transition zone at VR_max of around 1.5%. Significant decrease of volatile matter occurs in the zone between 0.5% and 2.0% VR_max. A sharp bend occurs at VR_max between 2.0% and 2.5%. Above 2.5%, the volatile matter decreases only very slightly. Between VR_r = 0.5% and 2.0%, the carbon content of the coals is ascending drastically. Above 2.5% VR_r, the carbon content becomes relatively stable (around 95 wt.%, daf).Vitrinite is the most abundant maceral in low rank coal (69.6–86.2 vol.%). Liptinite and inertinite are minor constituents. In the high rank coal, the thermally altered vitrinite composes 82.4–93.8 vol.%. Mosaic structures can be recognized as groundmasss and crack fillings. The most common minerals found are carbonates, pyrite or marcasite and clay minerals. The latter consist of kaolinite in low rank coal and illite and rectorite in high rank coal. Change of functional groups with rank increase is reflected most of all by the increase of the ratio of aromatic C–H to aliphatic C–H absorbances based on FTIR analysis. The Oxygen Index values of all studied coals are low (OI < 5 mg CO₂/g TOC) and the high rank coals have a lower Hydrogen Index (< 130 mg HC/g TOC) than the low rank coals (about 300 mg HC/g TOC). T_max increases with maturity (420–440 °C for low rank coals and 475–551 °C for high rank coals).Based on the above data, it was calculated that the temperature of contact metamorphism reached 700–750 °C in the most metamorphosed coal.     

Petrographic characteristics and depositional conditions of Eocene coals of platform basins, Meghalaya, India

The coal deposits of Meghalaya occur in the Lakadong Sandstone (25–250 m thick) of Eocene age. The coal-bearing formations are understood to have been deposited over platform areas in estuarine and lagoonal environments and subjected to recurrent marine transgressions and regressions during the Eocene period. There are three major groups of coalfields in Meghalaya, viz. Garo Hills (West Daranggiri and Siju Coalfields), Khasi Hills (Langrin and Mawlong–Shella Coalfields) and minor coalfields (Laitryngew, Cherrapunji and Bapung Coalfields). Pillar coal samples have been collected from 10 seams at 15 locations and have been subjected to a detailed petrographic examination for their characterization. An effort has been made to trace the path of their evolution based on coal petrography-based models. The quantitative petrographic analysis shows that these coals are vitrinite rich (45.0–92.9%, mean 73.4% mmf basis) with low concentration of inertinite (0.0–13.8%, mean 3.0% mmf basis), whereas the liptinite occurs in appreciable concentration (5.5–53.1%, mean 22.5% mmf basis). Further, these coals are rich in vitrite (51.6–100%, mean 78.3% mmf basis). The volatile matter (from 38.5% to 70.0%, d.a.f.) and vitrinite reflectance (Rom from 0.37% to 0.68%) characterize these coals, as per German (DIN) and North American classification, approximately as sub-bituminous ‘C' to high volatile ‘C' bituminous. The occurrence of teleutospore (single, double and triple celled) suggests that these coals have originated from a characteristic Tertiary flora. The maceral and microlithotype composition in the coal petrography-based depositional models suggest that the coals of Garo Hills were formed in reed to open water swamps in telmatic to limnic conditions. The coals of Khasi Hills were dominated by forest swamps and telmatic to limno-telmatic conditions. In addition, the occurrence of large-size resins suggests prolific growth of conifers in the swamps.     

Role of coal type and rank on methane sorption characteristics of Bowen Basin, Australia coals

The effect of coal composition, particularly the organic fraction, upon gas sorption has been investigated for Bowen Basin and Sydney Basin, Australia coals. Maceral composition influences on gas retention and release were investigated using isorank pairs of hand-picked bright and dull coal in the rank range of high volatile bituminous (0.78% R_{o max}) to anthracite (3.01% R_{o max}). Adsorption isotherm results of dry coals indicated that Langmuir volume (V_L) for bright and dull coal types followed discrete, second-order polynomial trends with increasing rank. Bright coals had a minimum V_L at 1.72% R_{o max} and dull coals had a minimum V_L at 1.17% R_{o max}. At low rank, V_L was greater in bright coal by about 10 cm³/g, but as rank increased, the bright and dull trends converged and crossed at 1.65% R_{o max}. At ranks higher than 1.65% R_{o max}, both bright and dull coals followed similar trends. These competing trends mean that the importance of maceral composition on V_L varies according to rank. In high volatile bituminous coals, increases in vitrinite content are associated with increases in adsorption capacity. At ranks higher than medium to low volatile bituminous, changes in maceral composition may exert relatively little influence on adsorption capacity. The Langmuir pressure (P_L) showed a strong relationship of decreasing P_L with increasing rank, which was not related to coal type. It is suggested that the observed trend is related to a decrease in the heterogeneity of the pore surfaces, and subsequent increased coverage by the adsorbate, as coal rank increases. Desorption rate studies on crushed samples show that dull coals desorb more rapidly than bright coals and that desorption rate is also a function of rank. Coals of lower rank have higher effective diffusivities. Mineral matter was found to have no influence on desorption rate of these finely crushed samples. The evolution of the coal pore structure with changing rank is implicated in diffusion rate differences.     

Methane and CO2 sorption and desorption measurements on dry Argonne premium coals: pure components and mixtures

Sorption and desorption behaviour of methane, carbon dioxide, and mixtures of the two gases has been studied on a set of well-characterised coals from the Argonne Premium Coal Programme. The coal samples cover a maturity range from 0.25% to 1.68% vitrinite reflectance. The maceral compositions were dominated by vitrinite (85% to 91%). Inertinite contents ranged from 8% to 11% and liptinite contents around 1% with one exception (Illinois coal, 5%). All sorption experiments were performed on powdered (−100 mesh), dry coal samples.Single component sorption/desorption measurements were carried out at 22 °C up to final pressures around 51 bar (5.1 MPa) for CO₂ (subcritical state) and 110 bar (11 MPa) for methane.The ratios of the final sorption capacities for pure CO₂ and methane (in molar units) on the five coal samples vary between 1.15 and 3.16. The lowest ratio (1.15) was found for the North Dakota Beulah-Zap lignite (VR_r=0.25%) and the highest ratios (2.7 and 3.16) were encountered for the low-rank coals (VR_r 0.32% and 0.48%) while the ratio decreases to 1.6–1.7 for the highest rank coals in this series.Desorption isotherms for CH₄ and CO₂ were measured immediately after the corresponding sorption isotherms. They generally lie above the sorption isotherms. The degree of hysteresis, i.e. deviation of sorption and desorption isotherms, varies and shows no dependence on coal rank.Adsorption tests with CH₄/CO₂ mixtures were conducted to study the degree of preferential sorption of these two gases on coals of different rank. These experiments were performed on dry coals at 45 °C and pressures up to 180 bar (18 MPa). For the highest rank samples of this sequence preferential sorption behaviour was “as expected”, i.e. preferential adsorption of CO₂ and preferential desorption of CH₄ were observed. For the low rank samples, however, preferential adsorption of CH₄ was found in the low pressure range and preferential desorption of CO₂ over the entire pressure range.Follow-up tests for single gas CO₂ sorption measurements consistently showed a significant increase in sorption capacity for re-runs on the same sample. This phenomenon could be due to extraction of volatile coal components by CO₂ in the first experiment. Reproducibility tests with methane and CO₂ using fresh sample material in each experiment did not show this effect.     

Adsorption Characteristics of Lignite in China

To help in ascertaining methane content of lignite reservoir in China,the isothermal ad-sorption measurements of methane have been performed on moisture-equilibrated coals of some typical lignite-bearing basins,which comprise maximum reflectance of vitrinite(Ro,max) ranging from 0.24% to 0.50%.Related to other coal properties,our analysis shows that methane adsorption of lignite is mainly affected by coalification,as well as by maceral composition,moisture content,and seam temperature.Maximum methane capaci...     

中煤级煤吸附甲烷的物理模拟与数值模拟研究

基于184个中煤级（镜质组最大反射率Ro,max介于0.65%~2.50%）煤在平衡水条件下的等温吸附实验成果,模拟了中煤级煤的朗格缪尔体积和压力与煤级的关系,建立了不同埋深（温度、压力）条件下不同煤级煤饱和吸附气量量板,探讨了压力和温度对中煤级煤吸附甲烷能力的综合效应,对比分析了中煤级煤吸附特征与低、高煤级煤的差异,提出了中煤级煤吸附气量预测的方法。     

Predicted CO2 emissions from maceral concentrates of high volatile bituminous Kentucky and Illinois coals

A large collection of well-characterized coals, documented in the Center for Applied Energy Research's (CAER) database, was used to estimate the CO₂ content of maceral concentrates from Kentucky and Illinois high volatile bituminous coals. The data showed no correlation between CO₂ versus coal ranks and between CO₂ versus maceral content. Subsequently, eight sets of low-ash density-gradient centrifugation (DGC) maceral concentrates from five coal beds were examined, spanning in the high volatile rank range. Heating value was not determined on the concentrates, but instead was calculated using the Mott–Spooner formula. There was a good correlation between predicted CO₂ and maceral content for the individual iso-rank (based on vitrinite reflectance, analyzed on whole (parent) coal) sets. In general, the predicted CO₂ increases from liptinite-rich through vitrinite-rich to inertinite-rich concentrates (note: no “concentrates” are absolutely monomaceral).     

Geology and characterisation of the Pecket coal deposit, Magellan Region, Chile

The geology, petrography and chemical variation of the Pecket coal sequence, Magellan Region (52°57′S, 71°10′W), the only Chilean coal used for electricity generation on a large scale, has been studied in order to predict their combustion behaviour, especially in coal blends. The depositional environment of formation of the coal seams was a swamp rarely exposed to subaerial conditions and was associated with the development of the folded foreland of the Magellan basin during the Tertiary (Oligo–Miocene). The general tectonic regime of the collision of the Antarctic and South American plates is reflected by a system of joints with 40°N–50°W strike. The maceral composition of all six seams studied indicates high contents of vitrinite (>90%), minor content of liptinite (4.7%) and inertinite (<2%). Occurrence of tonstein horizons altered to kaolinite indicates a distal volcanism during peat accumulation. Coal rank varies between lignite and subbituminous (Ro=0.28–0.42%) with an average dry basis calorific value of 5450 kcal/kg, 17 wt.% moisture, 41 wt.% volatile matter, and sulphur content below 0.5 wt.%. The mineral matter (LTA) associated with the coal shows a dominance of kaolinite with quartz, smectite, and minor basanite. SiO₂/Al₂O₃ and Fe₂O₃/CaO ratios of the ashes diminish towards the lower seams. With respect to the utilisation of Pecket coals in combustion, base/acid ratios (B/A) and silica ratios (SR) indicate potential fouling for seams 1, 2, 5, and 6i, with high fouling indexes (Rf) for seams 2 and 5. Pecket coal is excellent for blend combustion due to its low sulphur content.     

Studies of the relationship between coal petrology and grinding properties

The maceral and microlithotype composition of selected coals has been investigated with respect to the grinding properties, specifically Hardgrove grindability index (HGI), of the coals. The study expands upon previous investigations of HGI and coal petrology by adding the dimension of the amount and composition of the microlithotypes. Coal samples, both lithotypes and whole channels, were selected from restricted rank ranges based on vitrinite maximum reflectance: 0.75–0.80% R_max, 0.85–0.90% R_max and 0.95–1.00% R_max. In this manner, the influence of petrographic composition can be isolated from the influence of rank. Previous investigations of high volatile bituminous coals demonstrated that, while rank is an important factor in coal grindability, the amount of liptinite and liptinite-rich microlithotypes is a more influential factor. In this study, we provide further quantitative evidence for the influence of microlithotypes on HGI and, ultimately, on pulverizer performance.     

Oil-generating potential of Tertiary coals and other organic-rich sediments of the Nyalau Formation,onshore Sarawak

The oil-generating potential of coals and other organic-rich sediments from the Late Oligocene–Early Miocene Nyalau Formation, the offshore extension of which is believed to be a major source rock, is evaluated. Coals of the Nyalau Formation are typically dominated by vitrinite, with moderate and low amounts of exinite and inertinite, respectively. Significant amounts of clay minerals are present in these coals and those containing between 15 to 65% mineral matter by volume are termed carbargilite. The samples analysed range from sub-bituminous to high-volatile bituminous rank, possessing vitrinite reflectance in the range 0.42% to 0.72%. T_max values range from 425°–450°C which is in good agreement with vitrinite reflectance data. Good oil-generating potential is anticipated from these coals and carbargilites with moderate to rich exinite content (15–35%). This is supported by their high hydrogen indices of up to 400 mgHC/gTOC, Py–GC (S2) pyrograms with n-alkane/alkene doublets extending beyond nC₃₀, and their being in the early to mid-mature oil-window range. Petrographically, the most significant evidence of the oil-generating potential of these coals is the generation of petroleum-like materials (exsudatinite) visible under the microscope. Exsudatinite is a secondary maceral, commonly considered to represent the very beginning of oil generation in coal, which is shown here to also have an important role to play in hydrocarbon expulsion. The precursor of exsudatinite in these coals is the maceral bituminite which readily expels or mobilizes to hydrocarbon-like material in the form of oil smears and/or exsudatinite as observed under the microscope. The maceral bituminite is considered to play a major generative role via early exsudatinite generation, which is considered to facilitate the overall expulsion process in coaly source rocks.     

Chemical and petrographical characterization of feed coal, fly ash and bottom ash from the Figueira Power Plant, Paraná, Brazil

The aim of the present study is the petrographic and chemical characterization of the coal at the Figueira Power Plant, Paraná, Brazil, prior and after the beneficiation process and the chemical characterization of fly and bottom ashes generated in the combustion process.Petrographic characterization was carried out through maceral analysis and vitrinite reflectance measurements. Chemical characterization included proximate analysis, determination of calorific value and sulphur content, ultimate analysis, X-ray diffraction, X-ray fluorescence, Inductively Coupled Plasma — Mass Spectrometry (ICP-MS) and Inductively Coupled Plasma — Atomic Emission Spectrometry (ICP-AES) analysis, and determination of Total Organic Carbon (TOC) content.Vitrinite reflectance analyses indicate a high volatile B/C bituminous coal (0.61 to 0.73% Rrandom). Maceral analyses show predominance of the vitrinite maceral group (51.6 to 70.9 vol.%, m.m.f). Except of the Run of mine (ROM) coal sample, the average calorific value of the coals is 5205 kcal/kg and ash yields range from 21.4 to 38.1 wt.%. The mineralogical composition (X-ray diffraction) of coals includes kaolinite, quartz, plagioclase and pyrite, whereas fly and bottom ashes are composed by mullite, ettringite, quartz, magnetite, and hematite. Analyses of major elements from coal, fly and bottom ashes indicate a high SiO₂, Al₂O₃, and Fe₂O₃ content. Trace elements analysis of in-situ and ROM coals by ICP-MS and ICP-AES show highest concentration in Zn and As. Most of the toxic elements such as As, Cd, Cr, Mo, Ni, Pb, and Zn are significantly reduced by coal beneficiation. Considering the spatial distribution of trace elements in the beneficiated coal samples, which were collected over a period of three months, there appears to be little variation in Cd and Zn concentrations, whereas trace elements such as As, Mo, and Pb show a larger variation.In the fly and bottom ashes, the highest concentrations of trace elements were determined for Zn and As. When compared with trace element concentrations in the feed coal, fly ashes show a significant enrichment in most trace elements (As, B, Be, Cd, Co, Cr, Cu, Li, Mn, Mo, Ni, Pb, Sb, Tl, and Zn), suggesting a predominantly volatile nature for these elements. In contrast, Sn is distributed evenly within the different ash types, whereas U shows depleted concentration in both bottom and fly ash samples.According to the International Classification of in-seam coals the Cambuí coals are of para/ortho bituminous rank of low grade (except for the ROM sample), and are characterized by the predominance of vitrinite macerals.     

Evaluation of coal bed methane potential of coal seams of Sawang Colliery,Jharkhand, India

The coal seams of Sawang Colliery, East Bokaro Coalfields are bituminous to sub-bituminous in nature and categorized as high gaseous seams (degree II to degree III level). These seams have the potential for coal bed methane (CBM) and their maturity increases with increasing depth, as a result of enhanced pressure-temperature conditions in the underground. The vitrinite maceral group composition of the investigated coal seams ranges from 62.50–83.15%, whereas the inertinite content varies from 14.93–36.81%. The liptinite content varies from 0.66% to 3.09%. The maximum micro-pores are confined within the vitrinite group of macerals. The coal seams exhibit vitrinite reflectance values (Ro% calculated) from 0.94% (sample CG-97) to 1.21% (sample CG-119). Proximate analyses of the investigated coal samples reveal that the moisture content (M%) ranges from 1.28% to 2.98%, whereas, volatile matter (VM%) content is placed in the range of 27.01% to 33.86%. The ash content (A%) ranges from 10.92% to 30.01%. Fixed carbon (FC%) content varies from 41.53% to 55.93%. Fuel ratio variation shows a restricted range from 1.53 to 1.97. All the coal samples were found to be strongly caking and forming coke buttons. The present study is based on the adsorption isotherm experiments carried out under controlled P-T conditions for determination of actual gas adsorption capacity of the coal seams. This analysis shows that the maximum methane gas adsorbed in the coal sample CG-81 is 17 m³/t (Std. daf), at maximum pressure of 5.92 MPa and experimental temperature of 30°C. The calculated Langmuir regression parameters P_L and V_L range from 2.49 to 3.75 MPa and 22.94 to 26.88 m³/t (Std. daf), respectively.     

Initial volatilization temperatures and average volatilization rates of coal — Their relationship to coal rank and other characteristics

Two thermal parameters, initial volatilization temperature (IVT) and average volatilization rate (AVR), have been determined by thermogravimetric analysis in argon for 38 coal samples ranging in rank from lignite to low-volatile bituminous. Both IVT and AVR are correlated with percent volatile matter and vitrinite reflectance.The IVT values increase gradually from about 250 to 445°C with increasing rank; however, a change in slope is observed in the region of high-volatile bituminous coals (from about 340°C to about 380°C) when IVT's are plotted against percent volatile matter or percent fixed carbon. The changes in slope near 340°C and near 380°C occur at “coalification jumps” recognized on the basis of changes in the optical and chemical character of the macerals. In general, AVR values decrease gradually with increasing rank for the lignite and sub-bituminous coals and for the medium- and low-volatile bituminous coals; however, a sharp increase in AVR occurs in high-volatile bituminous coals. The change in slope of the IVT curves and sharp increase in the AVR values for high-volatile bituminous coals reflect the development of new, higher vapor pressure organic compounds produced during this stage of the coalification process.A plot of AVR vs IVT reveals three regions which correspond to: (1) lignite and sub-bituminous coals; (2) high-volatile bituminous coals; and (3) medium- to low-volatile bituminous coals.     

Petrographic characteristics of coal from Mailaram coalfield,Godavari valley,Andhra Pradesh

The quantitative maceral study of the Queen seam from Mailaram coalfield of Godavari valley has displayed alternate coal bands rich in vitrinite/liptinite or inertinite. The random vitrinite reflectance (R_o max. %) of these coals, from top part ranges from 0.50 to 0.64%. However, the bottom part of the seam has indicated lower reflectance, between 0.49 and 0.52%. Thus, the Queen seam, in general, has attained high volatile bituminous C rank. The study indicates that the depositional site has been a slowly sinking basin that witnessed alternate dry (oxidizing) and wet (reducing) spells. This subsequently caused fluctuation in water table of the basin and the formation of oxic and anaoxic moor condition, where accumulated vegetal resource transformed into mixed and fusic coal types in due course of time. Being high in liptinite and vitrinite contents and low mineral matter, the Queen seam of Mailaram coalfield has high economic potential.     

Aromatic components of coal: relation of distribution pattern to rank

Aromatic distribution patterns have been evaluated for a series of twenty-four German high volatile bituminous B to low volatile bituminous coals of Upper Carboniferous Westphalian C-, B- and A-ages using high performance liquid chromatography and glass capillary gas chromatography. The study concentrates on dicyclic and tricyclic aromatic hydrocarbons most of which have been identified by combined gas chromatography-mass spectrometry. The distribution patterns of the methylhomologs of naphthalene and phenanthrene are strongly controlled by rank. A sudden increase of individual isomer ratios at 0.9% Rm coincides with an abrupt shift of the sporinite fluorescence colour from yellow towards red. A recently developed aromatics-derived maturity parameter, the Methylphenanthrene Index (MPI), correlated well with the vitrinite reflectance data over the whole rank range. Deviations have been attributed to variations of maceral composition or migration phenomena. The influence of artificial thermal alteration (350 and 400dgC) on the aromatic distribution pattern of coal is described.