The geology, petrology and geochemistry of coal seams from the St. Rose and Chimney Corner coalfields, Cape Breton, Nova Scotia, Canada

Seams from the St. Rose and Chimmey Corner coalfields, Nova Scotia, Canada, were sampled and examined for petrographic and geochemical composition. Rank determinations indicate a rank of high volatile C-B bituminous. Seams show regular alternations of dull and bright microbanded lithotypes, with dull lithotypes predominant in the central portion of the main seam (No. 5 seam). Brighter lithotypes are dominated by vitrinite (>80%), with minor inertinite (avg. 12%) and minor liptinite. Duller lithotypes contain greater amounts of inertinite (up to 40%) and liptinite (primarily sporinite). Mineral matter consists of epigenetic pyrite, with lesser amounts of clay and quartz. Cabonates are common in the Chimney Corner seams. Elemental composition of the seams is similar to other Canadian coals and fall within world coal ranges, with the exception of high concentrations of Cl, Zn, Ni, Mo, Pb, Cu and As.Depositional environment of the seams as indicated by maceral composition, lithotypes and geology suggest a predominance of wet forest to reed moor conditions, in a fluvial-lacustrine setting. Periodic episodes of flooding and drying are indicated by lithotype, maceral and mineral variations.     

On the effects of petrographic composition on coalbed methane sorption

The effect of petrographic composition on the methane sorption capacity has been determined for a suite of coals and organic-rich shales. Subbituminous and bituminous coals were separated into bright and dull lithotypes by hand-picking. The methane sorption capacities range between 0.5 and 23.9 cm³/g at a pressure of 6 MPa. The low volatile bituminous Canmore coal and the anthracite sample have the highest capacities with the “natural coke” having the lowest. For low-rank coals there is no significant difference between bright and dull samples except for one coal with the dull sample having a greater sorption capacity than its bright equivalent. For higher-rank coals, the bright samples have a greater methane capacity than the dull samples and the difference between sample pairs increases with rank. The boghead coal samples have the highest sorption capacities in the liptinite-rich coals suite and are higher than subbituminous to medium volatile bituminous samples. Pore size distribution indicates that methane is held as solution gas in liptinite-rich coals and by physical sorption in micropores in liptinite-poor coals. These contrasting processes illustrate that liptinite-rich samples need to be independently assessed. The positive relationship between reactive inertinite content and methane sorption capacity occurs within the subbituminous to medium volatile bituminous coals because the reactive inertinite is structurally similar to vitrinite and have a higher microporosity than non-reactive inertinite. Reactivity of inertinite should be assessed in CBM studies of dull coals to provide a better understanding of petrographic composition effects on methane capacity.     

The geology, petrology, palynology and geochemistry of Permian coal basins in Tanzania: 2. Songwe-Kiwira Coalfield

This study provides coal quality, petrological, palynological and geochemical (Rock Eval) data on Permian coal seams and associated shales and mudstones of the Karoo Supergroup of the Songwe-Kiwira Coalfield, Tanzania. The coal seams, which have a cumulative thickness of 6.80 m, occur in the shale–coal–sandstone facies of the Mchuchuma Formation of Artinskian to Kungurian(?) age.Coal quality data (calorific values, volatile matter contents) and vitrinite reflectances indicate high volatile C bituminous to high volatile A bituminous coals, having relatively high ash yields (22–49 wt.%) and highly variable sulphur contents (0.17–9.2 wt.%). They could be used to fuel small-scale power generation units thereby providing electricity to nearby towns and villages. Also, the coals could be used as a substitute for wood, which is becoming increasingly scarce. In rural Tanzania, charcoal is still the main energy source for cooking, and wood is used extensively in brick kilns and for making roofing tiles.Petrological analysis indicated that the coals are dominated by dull to banded dull lithotypes, with seams at the base of the Mchuchuma Formation enriched in inertinite macerals (up to 83 vol.%), whereas up-section vitrinite contents increase. Palynological analyses indicated that the assemblage in the lower Mchuchuma Formation (Scheuringipollenites assemblage) is dominated by trilete spores, whereas in the remainder of the section, non-taeniate disaccates dominate (Scheuringipollenites–Protohaploxypinus assemblage). Facies critical macerals suggest for most seams a marsh/wet forest swamp depositional setting, which is consistent with the palynological data.Rock Eval analyses indicate type II/III kerogen, with Tmax (°C) values ranging from 426 to 440, corresponding to the early stage of hydrocarbon generation. Thermal Alteration Indices (2 to 2+) and vitrinite reflectance levels (0.60–0.83 Ro (%) support the Rock Eval maturity assessment, and despite the predominance of terrestrial-derived organic matter, there is evidence of oil generation and expulsion in the form of cavity and fracture filling exsudatinite.     

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.     

重庆中梁山矿区主要煤层的煤岩学和煤相特征

结合国际煤岩学会（ICCP）对显微组分的新分类系统,通过绘制显微组分三元图和煤相图,对重庆中梁山矿区主要煤层显微组分和煤相特征进行了研究。结果表明:该矿区宏观煤岩类型以半亮煤为主,且构造煤较发育;显微组分中以镜质组为主,其中以基质镜质体和碎屑镜质体最为常见。煤相研究表明,本区主要煤层形成于下三角洲平原或下三角洲平原到陆相沉积的过渡环境,属于近陆相的低位沼泽环境,成煤环境受海水作用明显。      

Facies and genesis of Carboniferous coal seams of Northwest Germany

In order to get detailed information about the facies and genesis of Upper Carboniferous coal seams of Northwest Germany, maceral analyses of complete seam profiles (Westphalian B-D, mainly Westphalian C) were carried out. Four main facies and twelve subfacies could be distinguished. The main facies are:

1. (1) The sapropelic-coal facies, consisting of fine-grained inertinite and liptinite, which forms from organic sediments deposited at the bottom of moor lakes.

2. (2) The densosporinite facies which is high in inertinite and liptinite and low in vitrinite. Syngenetic pyrites, clastic layers, thick vitrains and fusains do not occur. This facies originates from peats of ‘open mires’ with higher groundwater table and herbaceous vegetation. The ‘open mire’ was situated in the centre of extensive swamps. Consequently, clastic sedimentation did not affect this swamp type and nutrient supply and pH values were low.

3. (3) The vitrinite-fusinite facies, which is high in vitrinite. This is the result of abundant vitrains. Under the microscope, fusains were mostly identified as fusinite. The vitrinite-fusinite facies originates from a forest mire. More or less abundant seam splits and clastic layers show that rivers flowed in the neighbourhood of this area.

4. (4) The shaly-coal facies, which represents the most marginal part of the former swamp frequently affected by clastic sedimentation.

Within the Carboniferous of the Ruhr Region it seems unlikely that the thin coal seams of the Namurian C and Westphalian A1 contain a densosporinite facies. The swamps were situated in the lower delta plain where they were often affected by marine influences. Consequently, coals are high in minerals and sulfur and they are thin and discontinous. The best conditions for the formation of extensive swamps, with open mires (densosporinite facies) in their central parts, prevailed during Westphalian A2 and B1 times. Low contents of sulfur and minerals and high content of inertinite are typical for these coals. Sedimentation mainly took place in the transitional zone from the lower to the upper delta plain. During the Westphalian B2 and C fluvial sedimentation dominated. Within the coal seams minerals, sulfur and pseudovitrinite increase while inertinite decreases. This is the consequence of coal of the densosporinite facies occurring with increased rarity. The coal seams of the Westphalian C2 contain no densosporinite facies because peat formation was restricted by increasing fluvial sedimentation and by a better drainage. As a consequence, extensive swamps with ‘open mires’ in the centre were no longer formed after the formation of the “Odin” seams. Above the “Odin” seams coal of the vitrinite-fusinite facies contains thick-walled torisporinites. Variations and lowering of the groundwater table caused mild oxidative influences during peat formation. This is documented by an increase in pseudovitrinite, the occurrence of torisporinites and the absence of spheroidal sideritic concretions. Sulfur content increases in the absence of the low-ash and low-sulfur coal of the densosporinite facies.In Upper Carboniferous coal seams of the Ibbenbüren Region the inertinite and telocollinite contents are higher than in those of the Ruhr Region. Therefore, variations of the groundwater table have been more pronounced and resulting oxidative influences must have been more severe. Seldom occurring marine and brackish horizons and a higher fusinite (fusain) content indicate a slight elevation of this area. From Early Westphalian D times onward, peat formation was no longer possible because of the better drainage. This resulted in severe oxidative conditions which excluded peat formation.     

Organic petrology of Paleocene Marcelina Formation coals, Paso Diablo mine, western Venezuela: Tectonic controls on coal type

About 7 Mt of high volatile bituminous coal are produced annually from the four coal zones of the Upper Paleocene Marcelina Formation at the Paso Diablo open-pit mine of western Venezuela. As part of an ongoing coal quality study, we have characterized twenty-two coal channel samples from the mine using organic petrology techniques. Samples also were analyzed for proximate–ultimate parameters, forms of sulfur, free swelling index, ash fusion temperatures, and calorific value.Six of the samples represent incremental benches across the 12–13 m thick No. 4 bed, the stratigraphically lowest mined coal, which is also mined at the 10 km distant Mina Norte open-pit. Organic content of the No. 4 bed indicates an upward increase of woody vegetation and/or greater preservation of organic material throughout the life of the original mire(s). An upward increase in telovitrinite and corresponding decrease in detrovitrinite and inertinite illustrate this trend. In contrast, stratigraphically higher coal groups generally exhibit a ‘dulling upward’ trend.The generally high inertinite content, and low ash yield and sulfur content, suggest that the Paso Diablo coals were deposited in rain-fed raised mires, protected from clastic input and subjected to frequent oxidation and/or moisture stress. However, the two thinnest coal beds (both 0.7 m thick) are each characterized by lower inertinite and higher telovitrinite content relative to the rest of Paso Diablo coal beds, indicative of less well-established raised mire environments prior to drowning.Foreland basin Paleocene coals of western Venezuela, including the Paso Diablo deposit and time-correlative coal deposits of the Táchira and Mérida Andes, are characterized by high inertinite and consistently lower ash and sulfur relative to Eocene and younger coals of the area. We interpret these age-delimited coal quality characteristics to be due to water availability as a function of the tectonic control of subsidence rate. It is postulated that slower subsidence rates dominated during the Paleocene while greater foreland basin subsidence rates during the Eocene–Miocene resulted from the loading of nappe thrust sheets as part of the main construction phases of the Andean orogen. South-southeastward advance and emplacement of the Lara nappes during the oblique transpressive collision of the Caribbean and South American tectonic plates in the Paleocene was further removed from the sites of peat deposition, resulting in slower subsidence rates. Slower subsidence in the Paleocene may have favored the growth of raised mires, generating higher inertinite concentrations through more frequent moisture stress. Consistently low ash yield and sulfur content would be due to the protection from clastic input in raised mires, in addition to the leaching of mineral matter by rainfall and the development of acidic conditions preventing fixation of sulfur. In contrast, peat mires of Eocene–Miocene age encountered rapid subsidence due to the proximity of nappe emplacement, resulting in lower inertinite content, higher and more variable sulfur content, and higher ash yield.     

Petrographic characteristics and depositional conditions of Permian coals of Pench, Kanhan, and Tawa Valley Coalfields of Satpura Basin, Madhya Pradesh, India

This paper attempts to characterize the coals of Satpura Gondwana basin using a large number of pillar coal samples drawn from the working coal mines of Pench, Kanhan, and Tawa (Pathakhera) Valley Coalfields of this basin. This westernmost Gondwana basin of Peninsular India is graben/half-graben type and occupies an area of 12 000 km² with sedimentary fills (>5000 m) ranging in age from Permian to Cretaceous. The Barakar Formation (Permian) is exclusively coal-bearing with a total coal reserve of nearly 2000 Mt. The results show that the coals of this basin are equally rich in inertinite (22.8–58.7%, 24.5–62.0% mmf basis) and vitrinite (24.4–52.4%, 24.4–56.0% mmf basis). The concentration of liptinite ranges from 8.8% to 23.2% (9.0–26.0% mmf basis). The dominant microlithotypes of these coals are inertite and vitrite with comparatively low concentrations of vitrinertite and clarite. The vitrinite reflectance (Rom% values) suggests that the Pench Valley (0.30–0.58%) coals are subbituminous C to high volatile C bituminous in rank, while the Kanhan and Tawa Valley coals (0.52–0.92%) are subbituminous A to high volatile A bituminous in rank. The localized enhancement of rank in the latter two basins has been attributed to the extraneous heat flow from deep-seated igneous intrusions in the basin. The microlithotype composition of these coals is suggestive of their evolution in limno-telmatic zones, under fluvio-lacustrine control with the development of upper deltaic and lower deltaic conditions near the fresh water lacustrines. The floral input is characteristic of forest swamps with intermittent floods, leading to the development of reed moor and open moor facies, particularly in the Pench Valley basin. The Gelification Index (GI) and Tissue Preservation Index (TPI) are suggestive of terrestrial origin with high tree density. Further, moderately high GI and exceedingly high telovitrinite based TPI along with high ash content, particularly for the coals of Kanhan and Tawa Valley Coalfields, are indicative of the recurrence of drier conditions in the forested swamps. Furthermore, lateral variation in TPI values is indicative of increase in the rate of subsidence vis-à-vis depth of the basin from east to west (Pench to Tawa Valley Coalfield). The Ground Water Index (GWI) suggests that these coals have evolved in mires under ombotrophic to mesotrophic hydrological conditions. The Vegetation Index (VI) values are indicative of the dominance of herbaceous plants in the formation of Pench Valley coals and comparatively better forest input in the formation of Kanhan and Tawa Valley coals.     

Facies analysis of coal seams from the Cracow Sandstone Series of the Upper Silesia Coal Basin, Poland

The main purpose of this study was to recognise the variability of petrographical structure of two coal seams occurring in the Cracow Sandstone Series (Upper Carboniferous/Pennsylvanian, Upper Westphalian), being exploited in the Siersza mine. This mine is located in the eastern part of the Upper Silesia Coal Basin (USCB). The chemical analyses and petrographical features allow the inclusion of these coals to the group of hard brown coals belonging to subbituminous class.Two coal seams (207 and 209/210) of a considerable thickness (7.44 and 6.54 m, respectively), representative of the Cracow Sandstone Series (CSS), were chosen for the petrographic studies. Dominant macroscopic constituents of both seams are banded bright coal and banded coal.The coal seams were sampled in 284 intervals using a channel profile sampling strategy. The microscopical examinations revealed the majority of macerals from the vitrinite group (55%), followed by inertinite (21%), liptinite (11%), and mineral matter (13%). Low values of the vitrinite reflectance (R_o=0.46%) confirm very low coalification of the coal in both seams. Facies analysis indicates that in the course of a mire development, in which the studied coal seams originated, wet forest swamp conditions dominated characterized by a high degree of flooding and gelification as well as by a prevalence of arborescent plants. In such conditions, lithotypes with a large content of bright coal were mainly formed. Petrographic and facies data point to the rheotrophic character of these peatbogs. Frequent changes of the conditions in the peatbog, as it is shown by the variability of petrographic structure of the studied profiles, as well as by lateral changes of the phytogenic sedimentary environment within the coal seams, indicate a strong influence of a river channel on the adjoining peatbogs. An accretion of clastic sediments within the wide river channel belts was balanced mainly by the peatbog growth on the areas outside channels. Frequency and rate of avulsion of the river channels influenced the size, continuity and variability of the peatbogs.     

The Archean BIF-hosted Cuiabá Gold deposit, Quadrilátero Ferrífero, Minas Gerais, Brazil

The Cuiabá Gold Deposit is located in the northern part of the Quadrilátero Ferrífero, Minas Gerais State, Brazil. The region constitutes an Archean granite–greenstone terrane composed of a basement complex (ca. 3.2 Ga), the Rio das Velhas Supergroup greenstone sequence, and related granitoids (3.0–2.7 Ga), which are overlain by the Proterozoic supracrustal sequences of the Minas (< 2.6–2.1  Ga) and Espinhaço (1.7 Ga) supergroups.The stratigraphy of the Cuiabá area is part of the Nova Lima Group, which forms the lower part of the Rio das Velhas Supergroup. The lithological succession of the mine area comprises, from bottom to top, lower mafic metavolcanics intercalated with carbonaceous metasedimentary rocks, the gold-bearing Cuiabá-Banded Iron Formation (BIF), upper mafic metavolcanics and volcanoclastics and metasedimentary rocks. The metamorphism reached the greenschist facies. Tectonic structures of the deposit area are genetically related to deformation phases D₁, D₂, D₃, which took place under crustal compression representing one progressive deformational event (E_n).The bulk of the economic-grade gold mineralization is related to six main ore shoots, contained within the Cuiabá BIF horizon, which range in thickness between 1 and 6 m. The BIF-hosted gold orebodies (> 4 ppm Au) represent sulfide-rich segments of the Cuiabá BIF, which grade laterally into non-economic mineralized or barren iron formation. Transitions from sulfide-rich to sulfide-poor BIF are indicated by decreasing gold grades from over 60 ppm to values below the fire assay detection limit in sulfide-poor portions. The deposit is “gold-only”, and shows a characteristic association of Au with Ag, As, Sb and low base-metal contents. The gold is fine grained (up to 60 μm), and is generally associated with sulfide layers, occurring as inclusions, in fractures or along grain boundaries of pyrite, the predominant sulfide mineral (> 90 vol.%). Gold is characterized by an average fineness of 0.840 and a large range of fineness (0.759 to 0.941).The country rocks to the mineralized BIF show strong sericite, carbonate and chlorite alteration, typical of greenschist facies metamorphic conditions. Textures observed on microscopic to mine scales indicate that the mineralized Cuiabá BIF is the result of sulfidation involving pervasive replacement of Fe-carbonates (siderite–ankerite) by Fe-sulfides. Gold mineralization at Cuiabá shows various features reported for Archean gold–lode deposits including the: (1) association of gold mineralization with Fe-rich host rocks; (2) strong structural control of the gold orebodies, showing remarkable down-plunge continuity (> 3 km) relative to strike length and width (up to 20 m); (3) epigenetic nature of the mineralization, with sulfidation as the major wall–rock alteration and directly associated with gold deposition; (4) geochemical signature, with mineralization showing consistent metal associations (Au–Ag–As–Sb and low base metal), which is compatible with metamorphic fluids.     

Lower carboniferous coal deposition environments on Spitsbergen, Svalbard

Two coal-bearing units from the Lower Carboniferous succession in Central Spitsbergen, Svalbard, have been investigated using coal petrographic and geochemical techniques. The upper member consists mainly of algal cannels, dominated by Botryococcus-type algae. The coals from the lower member are a mixture of durite-type coals with sporinite and inertinite and coals containing prdominantly vitrinite. The Rock-Eval and pyrolysis-GC also show a clear distinction in the composition of the organic matter in the two coal-bearing units investigated. These results, together with detailed sedimentological analyses, are used to reconstruct the depositional environments for the two coal-bearing sequences.     

Petrography and geochemistry of Carboniferous coal seams in the Donets Basin (Ukraine): implications for paleoecology

The Carboniferous succession in the Donets Basin hosts about 130 seams, each with a thickness over 0.45 m. Nine economically important seams from the (south)western Donets Basin are studied using organic petrographical, inorganic geochemical, and organic geochemical techniques. The main aim of the study is the reconstruction of peat facies of Serpukhovian (Mississippian) and Moscovian (Middle Pennsylvanian) coals.Formation of major coal seams commenced during Serpukhovian times. Early Serpukhovian coal accumulated in a relatively narrow shore-zone and is rich in inertinite and liptinite. Very low ash yields, low to moderate sulphur contents, and upward increasing inertinite contents suggest coal deposition in raised mires.Moscovian coal has a significantly wider lateral extension and is generally rich in vitrinite. Coal properties vary widely in response to different peat facies. Low-sulphur, low-ash k₇ coal was formed in a raised mire or in a low-lying mire without detrital input. l₁ and l₃ seams containing several fluvial partings were formed in low-lying mires. Both seams are more than 2 m thick. Seams m₂ and m₃ contain high-sulphur coal, a consequence of deposition in a peat with marine influence. In contrast, syngenetic sulphur content is low in the m₅^{1 upper} seam, which was formed in a lacustrine setting. The late Moscovian n₁ seam, up to 2.4 m thick, accumulated in a swamp with a vegetation rich in bryophytes and pteridophytes. The properties of the n₁ seam are transitional between those of Serpukhovian and other Moscovian seams. Differences in maceral composition between Serpukhovian and Moscovian coals probably reflect changes in climate and vegetation type.Tuff layers are observed in the l₁, l₃, and m₃ seams. The l₃ and m₃ seams contain abundant authigenic quartz. Trace element contents are high in many seams. As contents are especially high in seams c₁₀², k₇, l₃ and m₃. Ash in the l₃ seam contains up to 8000 ppm As. Co is enriched near the base of several seams. Maxima up to 2400 ppm occur in the ash of the k₇ and l₃ seams. Cd contents in ash are frequently as high as 30 or 40 ppm.     

灵武煤田煤中镜质组与丝质组的甾萜类化合物对比研究

本文对灵武煤田含煤岩系延安组煤岩显微组分的甾萜类化合物作了对比研究．结果表明,同一沉积环境中镜质组与丝质组的甾萜类化合物特征及不同沉积环境中同一显微组分（镜质组或丝质组）的甾萜类化合物特征有着规律性的变化．     

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.     

Petrology of fibrous coal (fusain) and associated inertinites from the Early Paleocene of the central Alberta Plains

Megascopic, micropetrographic and scanning-electron microscopic investigations of fibrous coal indicate that paleo-wildfires were common occurrences in the mire which produced Highvale coals. At least 20 fibrous coal (fusain) horizons have been identified in corehole samples from the pit no. 3 locality at Highvale, in the central Alberta Plains. Thicknesses of individual horizons vary, and are not particular to any stratigraphic position within coal seams. The majority of these fibrous horizons is within the two thick economic seams, the Highvale Nos. 1 and 2, which are characteristically megascopically dull. The dullness of given lithotypes is largely related to inertinite content with fibrous coal containing 51% inertinite on average, and selected horizons comprised of as much as 85% inertinite. Semifusinite and inertodetrinite are the predominant inertinites, with a few horizons exhibiting highly reflecting fusinite. Macrinite is rare, and micrinite is absent. SEM investigations reveal that certain fibrous coals exhibit excellent preservation of the original gymnospermous (Taxodium) woody tissue. Features such as homogenization and swelling of the cell walls, elimination of the middle lamellae, and preservation of bordered pits are clearly indicative of charcoal formation as a product of paleo-wildfires. Depending upon the nature of the fire, temperatures obtained and the nature of the mire vegetation, a wide range of inertinite precursors can be produced.     

Microfacies and depositional environment of Tertiary Tanjung Enim low rank coal, South Sumatra Basin, Indonesia

The South Sumatra basin is among the most important coal producing basins in Indonesia. Results of an organic petrography study on coals from Tanjung Enim, South Sumatra Basin are reported. The studied low rank coals have a mean random huminite reflectance between 0.35% and 0.46% and are dominated by huminite (34.6–94.6 vol.%). Less abundant are liptinite (4.0–61.4 vol.%) and inertinite (0.2–43.9 vol.%). Minerals are found only in small amounts (0–2 vol.%); mostly as iron sulfide.Based on maceral assemblages, the coals can be grouped into five classes: (1) humotelinite-rich group, (2) humodetrinite-rich group, (3) humocollinite-rich group, (4) inertinite-rich group and (5) humodetrinite–liptinite-rich group. Comparing the distribution of maceral assemblages to the maceral or pre-maceral assemblages in modern tropical domed peat in Indonesia reveals many similarities. The basal section of the studied coal seams is represented typically by the humodetrinite–liptinite-rich group. This section might be derived from sapric or fine hemic peat often occurring at the base of modern peats. The middle section of the seams is characterized by humotelinite-rich and humocollinite-rich groups. The precursors of these groups were hemic and fine hemic peats. The top section of the coal seams is typically represented by the humodetrinite-rich or inertinite-rich group. These groups are the counterparts of fibric peat at the top of the modern peats. The sequence of maceral assemblages thus represents the change of topogenous to ombrogenous peat and the development of a raised peat bog.A comparison between the result of detailed maceral assemblage analysis and the paleodepositional environment as established from coal maceral ratio calculation indicates that the use of coal maceral ratio diagrams developed for other coal deposits fails to deduce paleo-peat development for these young tropical coals. In particular, mineral distribution and composition should not be neglected in coal facies interpretations.     

Petrological, organic geochemical and geochemical characteristics of coal from the Soko mine, Serbia

A petrological, organic geochemical and geochemical study was performed on coal samples from the Soko Mine, Soko Banja basin, Serbia. Ten coal and two carbonaceous clay samples were collected from fresh, working faces in the underground brown coal mine from different parts of the main coal seam. The Lower Miocene, low-rank coal of the Soko Mine is a typical humic coal with huminite concentrations of up to 76.2 vol.%, liptinite less than 14 vol.% and inertinite less than 11 vol.%. Ulminite is the most abundant maceral with variable amounts of densinite and clay minerals. Sporinite and resinite are the most common macerals of the liptinite group. Inertodetrinite is the most abundant maceral of the inertinite group. The mineral-bituminous groundmass identified in some coal samples, and carbonaceous marly clay, indicate sub-aquatic origin and strong bacterial decomposition. The mean random huminite reflectance (ulminite B) for the main coal seam is 0.40 ± 0.05% Rr, which is typical for an immature to early mature stage of organic matter.The extract yields from the coal of the Soko Banja basin ranges from 9413 to 14,096 ppm, in which alkanes constituted 1.0–20.1%, aromatics 1.3–14.7%, asphaltenes 28.1–76.2% and resins 20.2–43.5%. The saturated hydrocarbon fractions included n-C₁₅ to n-C₃₂, with an odd carbon number that predominate in almost all the samples. The contents of n-C₂₇ and n-C₂₉ alkanes are extremely high in some samples, as a contribution of epicuticular waxes from higher plants. Acyclic isoprenoid hydrocarbons are minor constituents in the aliphatic fraction, and the pristane/phytane (Pr/Ph) ratio varies between 0.56 and 3.13, which implies anaerobic to oxic conditions during sedimentation. The most abundant diterpanes were abietane, dehydroabietane and 16α(H)-phyllocladane. In samples from the upper part of the coal seam, diterpanes are the dominant constituents of the alkane fraction. Polycyclic alkanes of the triterpane type are important constituents of alkane fractions. The occurrence of ββ- and αβ-type hopanes from C₂₇ to C₃₁, but without C₂₈, is typical for the Soko Banja coals.The major and trace elements in the coal were analysed using X-ray fluorescence (XRF), and inductively coupled plasma-mass spectrometry (ICP-MS). In comparison with world lignites, using the geometric mean value, the coal from the Soko Banja Basin has a high content of strontium (306.953 mg/kg). Higher values than the world lignites were obtained for Mo (3.614 mg/kg), Ni (8.119 mg/kg), Se (0.884 mg/kg), U (2.642 mg/kg) and W (0.148 mg/kg). Correlation analysis shows inorganic affinity for almost all the major and trace elements, except for S, which has an organic affinity.     

吐哈盆地库姆塔格煤田西山窑组煤层煤相分析

以沉积学、煤岩学和煤相学理论为指导,运用煤相参数,结合宏观、微观煤岩特征分析煤相类型。结果表明:研究区宏观煤岩类型以暗淡型煤为主,显微煤岩类型以微镜惰煤为主,煤田西北部属潮湿-弱覆水环境,东南部属极潮湿-覆水环境;西北部煤层沼泽类型为干燥森林沼泽相,东南部以潮湿森林沼泽相为主,次为干燥森林沼泽相,沉积环境主要为浅沼相。综合分析认为,库姆塔格煤田煤层形成环境为低水位微弱水动力条件下、以潮湿森林沼泽为主、干燥森林沼泽次之的浅沼相,煤岩和煤相分析为聚煤环境分析、煤质评价、煤层对比等提供科学依据。     

Coal petrographical characterization of the Mecsek bituminous coal basin, with special reference to the contact metamorphism of coal seams

The bituminous coals of the Mecsek Mountains were formed during the Early Lias and are of paralic origin. The limnic complex of the layers consists of sandstone, aleurite and coal, and the upper layer contains marl of marine origin. The 9–15 minable coal seams have a thickness of 1.2–14.0 m. The Mecsek Coal Field and the coal complex within it show a folded and fractured structure, and with regard to their mechanical behaviour, are strongly stressed.75–90% of the coal material is vitrinite, and 1–14% is inertinite. The quantity of liptinite is smaller than 9%. The coal rank is that of gas coal and fat coal with a reflectivity of 0.85–1.5%, respectively. The coal rank differences and variations according to zones are the consequence of forces of various magnitude that occurred in the course of orogenic movements.During the Early Cretaceous, there was some under-sea-bed volcanic activity in this field, the diabasic material of which appeared in the form of a bed vein along the coal seams, and this has exerted a strong metamorphic influence on the coal. It has resulted in thermo-contact alteration, i.e. in the appearance of natural coke and semicoke of various degrees of metamorphism. This alteration badly affected the quality and technological characteristics, especially the cokability of the coal.     

Peat-forming environments of Westphalian A coal seams from the Lower Silesian Coal Basin of SW Poland based on petrographic and palynologic data

The petrographic and palynologic compositions of coal seams of the acler formation (Upper Carboniferous, Westphalian A) from northwestern and southeastern part of the Lower Silesian Coal Basin (LSCB) were examined. Coals studied are highly volatile bituminous coal, where R_o ranges from 0.91% to 1.09%. Seam 430 from the northwestern part of the basin contains high vitrinite percentage with rather low inertinite and liptinite contents, while percentage of mineral matter is variable. This petrographic composition is associated either with a predominance of Lycospora in miospore assemblage, or with a miospore assemblage of mixed character. The abundance of Lycospora reflects vegetation composed of the arborescent lycopsids while the mixed miospore assemblage is connected with diverse palaeoplant communities, namely, arborescent lycopsids, calamites and ferns. Seams 409 and 412/413 from the southeastern part of the LSCB are rich in inertinite and liptinite, while the vitrinite content is moderate. Their characteristic feature is the occurrence of a diagnostic crassisporinite (densosporinite). Amount of the mineral components in these coals is very low. Densosporites and related crassicingulate genera are main components of these miospore assemblages and were produced by herbaceous and/or sub-arborescent lycopsids. These petrographic and palynologic features were the basis for distinguishing three maceral–miospore associations: an arborescent lycopsid and mixed associations, occurring in the seam 430 and a herbaceous and/or sub-arborescent lycopsid association which was recorded in seams 409 and 412/413. The first two assemblages are interpreted as having been deposited in a planar rheotrophic mire, whereas the herbaceous and/or sub-arborescent lycopsid association is thought to have developed in an ombrotrophic, domed mire.