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1.
The gross chemical structures of xylites and gelified soft brown coal woods, Latrobe Valley, Victoria, Australia, as determined by solid state nuclear magnetic resonance spectroscopy, are compared with those of present-day wood-derived materials prepared from an angiosperm, Eucalyptus regnans, and a gymnosperm (conifer), Pinus radiata. Also examined are the changes in the gross chemical structures of soft brown coal woods with increase in their degree of gelification and the relationship between these changes and variations in their chemical composition and microscopic appearance.The Victorian xylites exhibit greater affinities with the present-day gymnosperm than the present-day angiosperm. The progressive removal of cellulose with increasing degree of gelification can be equated with an increase in huminite reflectance, elimination of humotelinite autofluorescence and changes in the relative proportions of the humotelinite submacerals. The lignin structure of xylite is also modified during the gelification process, including the progressive loss of methoxyl groups and evidence of minor oxidation. 相似文献
2.
Nigel J. Russell 《International Journal of Coal Geology》1984,4(2):99-118
The relationship between chemical composition and microscopic appearance of present-day wood-derived materials and Victorian xylites and gelified soft brown coal woods, Latrobe Valley, Australia, is discussed. The present-day wood-derived material consists of milled wood and lignin and holocellulose fractions prepared from an angiosperm, Eucalyptus regnans and a gymnosperm, Pinus radiata. The xylites and least gelified soft brown coal woods resemble the P. radiata lignin fraction; the latter contains residual cellulose.The atomic H/C ratio was found to be a useful guide to the degree of gelification. Increase in the degree of gelification was accompanied not only by an increase in the total huminite reflectance, but also by an increase in the reflectance of the individual huminite submacerals. The loss of hymotelinite autofluorescence under ultraviolet and blue light excitation with increase in the degree of gelification of Victorian soft brown coal woods was ascribed primarily to the elimination of cellulose and, possibly, modification of the lignin structure of xylite. 相似文献
3.
Settlement of compacted ash fills 总被引：1，自引：0，他引：1
The coal ash is a by-product of coal-fired thermal power station. It is extensively used as a geo-material for landfill. The
compacted ash is used as a structural fill if it is properly characterized for load-bearing capacity and settlement. The main
objective of the present work is to characterize ash material and to evaluate its settlement characteristics. The ash is normally
compacted by vibration at or near optimum moisture for its performance as structural fill. The overt characteristics of ashes
are viewed similar to cohesionless soils. However, the mass behavior may have differences due to the subtle influence of chemical
and physical processes involved in its formation. The empirical and analytical methods predicting settlement of footing under
static loading require direct or indirect measurement of density and stress state in the deposit. In the present work, experimental
investigations for settlement prediction were carried out on compacted coal ash produced at Ropar thermal power station in
India, which was conveniently classified as ASTM class F ash. The settlement was experimentally obtained for the rigid plates having least dimension more than 0.3 m on ashes compacted
at varying degree of compaction. The predicted settlement based on the observed data of coal ash using conventional techniques
for soils was found to be conservative. A relationship between settlement and foundation size is proposed at varying compaction
to obtain the settlement of compacted ash. At a higher degree of compaction, the settlement of a foundation may not exceed
the allowable settlements in the working stress range. 相似文献
4.
Coal of the Narragansett basin generally has been considered to be anthracite and/or meta-anthracite. However, no single reliable method has been used to distinguish these two ranks in this basin. Three methods — chemical, X-ray, and petrographic — have been used with some degree of success on coal of the Narragansett basin, but too often the results are in conflict. Chemical methods have been limited by inadequate sampling on a coal-bed-by-coal-bed basis and by a lack of analyses made according to (American Society for Testing and Materials, 1974) standard specifications.In addition, when corrections are made by using the Parr formulas, as required by the ASTM (1974) procedures, the generally high to very high ash content of coal from the Narragansett basin causes the fixed-carbon content to appear higher than it actually is. X-ray methods using the degree of graphitization as a measure of rank are not reliable because some of the graphite is related to shearing and brecciation associated with folding and faulting. Petrographic methods using reflectance on vitrinite give results that are generally consistent with results from chemical determinations. However, it is not clear whether the mean maximum reflectance or mean bireflectance is a better indicator of similar rank of such high-rank coals that have been structurally deformed.Coal from the Cranston Mine, RI, is probably meta-anthracite and coal from the Portsmouth Mine is probably anthracite. These ranks are based on chemical,X-ray, and petrographic data and are supported by associated metamorphic mineral assemblages that indicate that the Cranston Mine is in a higher metamorphic zone than the zone containing the Porthmouth Mine. Interpretation of the rank of Mansfield, MA, coal on the basis of extant chemical data is difficult because it is an impure coal with an ash content of 33 to 50%. Reflectance data indicate that the Mansfield, Foxborough, and Plainville coals in the northern part of the Narragansett basin are meta-anthracite but this is in disagreement with the rank suggested by the low degree of metamorphism of the associated rocks. 相似文献
5.
S. M. Moosavirad J. Rasouli M. R. Janardhana M. R. Moghadam M. Shankara 《Arabian Journal of Geosciences》2013,6(10):3623-3634
This paper discusses the result of the detailed investigations carried out on the coal characteristics, including coal petrography and its geochemistry of the Pabedana region. A total of 16 samples were collected from four coal seams d2, d4, d5, and d6 of the Pabedana underground mine which is located in the central part of the Central-East Iranian Microcontinent. These samples were reduced to four samples through composite sampling of each seam and were analyzed for their petrographic, mineralogical, and geochemical compositions. Proximate analysis data of the Pabedana coals indicate no major variations in the moisture, ash, volatile matter, and fixed carbon contents in the coals of different seams. Based on sulfur content, the Pabedana coals may be classified as low-sulfur coals. The low-sulfur contents in the Pabedana coal and relatively low proportion of pyritic sulfur suggest a possible fresh water environment during the deposition of the peat of the Pabedana coal. X-ray diffraction and petrographic analyses indicate the presence of pyrite in coal samples. The Pabedana coals have been classified as a high volatile, bituminous coal in accordance with the vitrinite reflectance values (58.75–74.32 %) and other rank parameters (carbon, calorific value, and volatile matter content). The maceral analysis and reflectance study suggest that the coals in all the four seams are of good quality with low maceral matter association. Mineralogical investigations indicate that the inorganic fraction in the Pabedana coal samples is dominated by carbonates; thus, constituting the major inorganic fraction of the coal samples. Illite, kaolinite, muscovite, quartz, feldspar, apatite, and hematite occur as minor or trace phases. The variation in major elements content is relatively narrow between different coal seams. Elements Sc,, Zr, Ga, Ge, La, As, W, Ce, Sb, Nb, Th, Pb, Se, Tl, Bi, Hg, Re, Li, Zn, Mo, and Ba show varying negative correlation with ash yield. These elements possibly have an organic affinity and may be present as primary biological concentrations either with tissues in living condition and/or through sorption and formation of organometallic compounds. 相似文献
6.
Relations of petrographical and geochemical parameters in the middle Miocene Lavanttal lignite (Austria) 总被引：1，自引：1，他引：1
A. Bechtel D. Reischenbacher R.F. Sachsenhofer R. Gratzer A. Lücke W. Püttmann 《International Journal of Coal Geology》2007,70(4):325-349
Samples from two lignite seams (Lower Seam, Upper Seam) of the Lavanttal basin (Austria) and additional xylite were investigated for variations in maceral composition, petrography-based facies indicators, bulk geochemical parameters, and molecular composition of hydrocarbons. Both seams originated in a topogenous mire and evolved within a transgressive setting. The final drowning of the mire is indicated by sapropelic shales. Whereas the sapropelic shale overlying the Lower Seam was deposited in a freshwater lake, the sapropelic shale above the Upper Seam represents a brackish lake.Numerous relationships are found between petrography-based facies indicators and the geochemical composition of organic matter. The contents of macerals of the liptinite group are positively correlated with soluble organic matter (SOM) yields and hydrogen index (HI). Consistent with maceral composition and high HI values, enhanced proportions of short-chain n-alkanes, which are predominantly found in algae and microorganisms, are obtained from samples of the sapropelic shales. The final drowning of the mire is reflected by decreasing pristane/phytane ratios, due to the rise in (ground)water table and the establishment of anaerobic conditions, as well as by decreasing ratios of diasterenes/sterenes, indicating increasing pH values in the mire. The degree of gelification of plant tissue (gelification index) is governed by the microbial activity in the mire, as indicated by the hopanes concentration. The differences in floral assemblage during the formation of the Lavanttal lignite seams are reflected by major differences in tissue preservation. Preservation of plant tissue (TPI) in the Lavanttal lignite is obviously controlled by the presence/absence of decay-resistant gymnosperms in the peat-forming vegetation, and additionally influenced by the relative contribution of wood to coal formation. The results provide evidence that valuable information for coal facies characterization could be obtained by petrography-based and geochemical facies indicators. An influence of the floral assemblage (gymnosperms/angiosperms ratio) and of the contribution of algal biomass on carbon isotopic composition of the organic matter (δ13C = − 24.2 to − 28.6‰) is proposed. Carbon cycling during biogeochemical decomposition of plant tissue by bacteria is suggested to affect the δ13C values of the coal. The chemotaxonomical classification of the xylites as gymnosperm remnants, based on the molecular composition of terpenoid biomarkers, is corroborated by the carbon isotopic composition of the xylites (mean δ13C = − 24.1‰) and the extracted cellulose (mean δ13C = − 20.2‰). The higher isotopic difference of about 3.9‰ between cellulose and total organic carbon of the xylites, compared to the difference between cellulose and wood found in modern trees, is explained by the smaller effect of decomposition on δ13C of cellulose. 相似文献
7.
Xylites are promising materials for activated carbon manufacturing due to their low rank, low inorganic content, and structural characteristics similar to the strong consistence of wood. These are similar to the classical adsorbents used for waste water purification, and available and profitable in the long term. This study has been undertaken to provide by means of petrographic data, new information on the porous structure development in chars during direct heating carbonization and physical activation. The xylite petrographic composition is very important, mainly due to the existence of structured wooden material – textinite with round and elongated cells – that influences the development of the structure and texture during carbonization and activation. The charcoal microstructure reveals some interesting aspects about the carbonization process with regard to evolution, efficiency and pore development. In the xylite activated carbon, the adsorption surface development by means of the highly porous system depends on the type of petrographical components, raw material grain size, and carbonization parameters. 相似文献
8.
Anne M. Graese David N. Baynard James C. Hower John C. Ferm Yuejin Liu 《International Journal of Coal Geology》1992,21(4)
The stratigraphic and regional variation of petrographic and chemical properties within the coals of the Upper Carboniferous Tradewater Formation and surrounding rocks in the Western Kentucky coal field were analyzed with the intent of constructing a depositional model for the occurrence of these low sulfur coals. Cores were megascopically described, and coal samples were analyzed for maceral, ash, and sulfur contents. These data were then analyzed to determine regional variation within the study area, as well as vertical variation within single coal columns.Sedimentological data from core logs indicate that the majority of the Tradewater rocks consist of irregularly distributed, coarsening-upward, fine-grained detrital material that was deposited in shallow bodies of water. Fossiliferous shales and limestones indicate a marine influence. Less common coarse-grained, fining-upward sequences appear to represent deposits of meandering or braided channels.Like the detrital rocks, the coal seams are irregularly distributed and exhibit substantial variation in petrographic and chemical properties which reflect changes in the Eh and pH of the coal swamp waters. These individual swamps were relatively limited in extent and probably occupied a low-lying coastal area. The relatively high vitrinite content of most of the coals suggests a reasonable degree of preservation of decaying plant materials. The study of benched samples from surface mines suggests a distinct dichotomy between swamps that were in more or less continuous contact with sulfate-rich marine or brackish water and those in which peat accumulated in a dominantly fresh-water setting. Most of the latter show a pattern of upward increasing sulfur content and decreasing vitrinite content, indicating increasing influences of oxygenated water that would encourage microbial action and which would degrade the peat and increase the tendency for sulfide precipitation. The high sulfur coals do not display this variability. The high rates of lateral variability encountered in the data suggest that future study should concentrate on smaller areas where variation can be completely documented. 相似文献
9.
利用煤岩学的理论和方法,对煤灰分中氧化钙(CaO)含量与煤样煤岩特征的关系进行了探讨。结果表明:煤灰分中氧化钙含量与其宏观煤岩特征的关系比较密切,用宏观煤岩特征可以预测煤灰中氧化钙的含量。 相似文献
10.
Curragh Queensland Mining Limited, Australia, produces a high quality medium volatile bituminous coking coal from the Orion, Pollux and Castor seams from the upper Permian Rangal Coal Measures. It is one of the lowest ash, prime hard coking coal blends produced in Australia. It is also low in sulfur and produces very strong coke when carbonized alone and in blends. Early attempts to predict coking properties of the coals from petrographic data produced predicted coke stabilities that were significantly lower than those determined from coke tests. There is some question as to how much of the ‘inertinite’ in these and other southern hemisphere coals is truly inert during carbonization and how much is reactive. The current study characterized the Curragh coals in terms of physical, chemical and petrographic characteristics and also involved the production of test oven cokes for characterization and strength testing. As part of the work effort a series of suggested techniques for improving predictions of coke strength from petrographic data were examined and a new and improved technique was developed for the Curragh coals. How broadly the technique can be applied to other coals needs to be determined. 相似文献
11.
塔里木盆地东南缘下—中侏罗统煤层沿阿尔金山前断续分布,其煤岩、煤质与典型的西北侏罗纪煤层具有明显不同。通过对和田布雅、于田普鲁、且末红柳沟等煤矿主采煤层样品进行煤岩、煤质鉴定及煤化指标等一系列综合研究分析,结果表明,主采煤层以光亮煤、半亮煤为主,其次是半暗煤、暗淡煤;煤岩组分以镜质组为主,壳质组含量少,具中-高镜惰比。因成煤沼泽的还原程度促进了无机硫分的形成,煤中全硫含量随镜质组含量的增加呈现逐渐增高的趋势,且煤层硫分与灰分整体具有明显的负相关关系。此外,煤层挥发分受不同种类硫分的影响,亦有明显差异性变化。在民丰凹陷中-高硫煤中,硫分以无机硫为主,随着硫分的升高挥发分亦有升高趋势;瓦石峡凹陷中-低硫煤受有机硫控制,对挥发分产率的影响不明显。民丰凹陷煤层的灰分指数高于瓦石峡凹陷,可见后者的成煤沼泽环境潜水面要比前者高得多。针对上述诸多因素分析,进一步揭示塔东南地区煤岩、煤质多样性变化受断陷湖盆以及局部水体较深的还原型沼泽环境控制,最终形成了中-高挥发分、中-低灰分、中-低硫分的煤质及富镜贫惰的煤岩特征。 相似文献
12.
Greta M. Eskenazy 《Geochimica et cosmochimica acta》1980,44(7):1023-1027
The content and distribution of In in 168 samples from 7 coal deposits in Bulgaria were studied, using a spectrochemical method with a detection limit of 0.002 ppm. Indium is present in all samples, its content varying from 0.002 to 0.167 ppm in the coal and from 0.005 to 0.57 ppm in the ash. The mean contents for individual deposits do not differ statistically, and for all the deposits the In concentration (ppm) can be expressed generally by the equation In = 0.00068 A (A is the coal ash content in %).Of the petrographic constituents of coal, vitrain, xylene and liptain are enriched in In. In is associated with both the organic and with the inorganic matter of the coal. Inorganic matter and clay minerals in particular, act only as carriers of Indium. In contrast, organic matter concentrates In only to a small degree relative to other trace elements. 相似文献
13.
The replacement of coal with other energy sources is due to the presence of harmful impurities such as sulfur that can lead to emission of harmful and corrosive gases such as H2S and SO2. These gases can affect the human health due to its toxicity. Also, the mineral matter (ash) can cause several types of respiratory system diseases due to the presence of heavy metals and formation of hazardous compounds while burning of coal. In order to avoid the production of such emissions, the researchers all over the world were looking for a methodology that can eliminate or reduce these impurities from coal. Therefore, the current study aims at decreasing the sulfur and ash content in Egyptian coal (Maghara coal), using bioflotation technique. The effect of Bacillus subtilis (B. subtilis) on the removal/reduction of sulfur and ash was investigated. The affinity of B. subtilis to coal surface was characterized using zeta-potential, adsorption tests and Fourier transform infrared. The bioflotation results showed that, at optimum conditions, a clean coal contains 0.92 % total sulfur and 1.95 % ash and yield exceeding 72 % was obtained from the starting coal containing 3.3 % sulfur and 6.65 % ash. 相似文献
14.
Maria Mastalerz James C Hower Agnieszka Drobniak Sarah M Mardon Grzegorz Lis 《International Journal of Coal Geology》2004,59(3-4):171-192
This paper presents data on the properties of coal and fly ash from two coal mines and two power plants that burn single-source coal from two mines in Indiana. One mine is in the low-sulfur (<1%) Danville Coal Member of the Dugger Formation (Pennsylvanian) and the other mines the high-sulfur (>5%) Springfield Coal Member of the Petersburg Formation (Pennsylvanian). Both seams have comparable ash contents (11%). Coals sampled at the mines (both raw and washed fractions) were analyzed for proximate/ultimate/sulfur forms/heating value, major oxides, trace elements and petrographic composition. The properties of fly ash from these coals reflect the properties of the feed coal, as well as local combustion and post-combustion conditions. Sulfur and spinel content, and As, Pb and Zn concentrations of the fly ash are the parameters that most closely reflect the properties of the source coal. 相似文献
15.
16.
Paul C. Lyons Carolyn L. Thompson Patrick G. Hatcher Floyd W. Brown Michael A. Millay Nikolaus Szeverenyi Gary E. Maciel 《Organic Geochemistry》1984,5(4):227-239
An evaluation was made of the degree of coalification of two coal balls from the Illinois Basin of the Pennsylvanian (upper Carboniferous) of the United States. Previous interpretations are mainly misleading and contradictory, primarily because of the assumption that the brown color and exceptional cellular and subcellular preservation typical of American coal balls imply chemical preservation of cellulose and lignin, the primary components of peat. Xylem tissue from a medullosan seed fern contained in a coal ball and the coal attached to the coal ball from the Calhoun coal bed, Mattoon Formation, Illinois, was analyzed by elemental, petrographic, and nuclear magnetic resonance (NMR) techniques to determine the degree of coalification. The NMR and elemental data indicate the lack of cellulose and lignin and a probable rank of high-volatile C bituminous coal. These data corroborate data for a coal ball from the Herrin (No. 6) coal bed (Carbondale Formation, Middle Pennsylvanian) and support our hypothesis that the organic matter in coal balls of the Pennsylvanian strata of the United States is coalified to about the same degree as the surrounding coal. Data presented show a range of lower reflectances for xylem tissue and vitrinite in the analyzed coal balls compared with vitrinite in the attached coal.The data reported indicate that physical preservation of organic matter in coal balls does not imply chemical preservation. Also our study supports the hypothesis that compactional (static load) pressure is not a prerequisite for coalification up to a rank of high-volatile C bituminous coal.A whole-rock analysis of the Calhoun coal ball indicates a similarity to other carbonate coal balls from the United States. It consists primarily of calcium carbonate and 1–2% organic matter; silica and alumina together make up less than 0.5%, indicating the lack of minerals such as quartz and clays. 相似文献
17.
华能南京电厂不同粒径粉煤灰中微量元素分布及其富集规律 总被引：8，自引：3，他引：8
华能南京电厂不同粒径粉煤灰的化学成分和矿物相组成基本相同，煤粉所含矿物质在高温燃烧过程中的挥发－凝聚作用，导致微量元素趋向细粒径粒煤灰中富集，其富集的程度则与粉煤灰的平均粒径和元素的地球化学性质密切相关，粉煤灰排放的环境效应表明，尤以细粒径灰粒的影响最大。 相似文献
18.
宁东煤田侏罗纪煤炭资源量巨大,是当前宁夏回族自治区煤炭资源开发利用的主体。为保障煤炭资源的清洁高效利用,以煤田大量勘查资料为主要依据,分析了宁东煤田侏罗纪煤的煤岩、煤质特征。结果显示:宁东煤田侏罗纪煤具有特低-低灰、特低-低硫、低磷、低砷、低氟、高发热量的特征,这些特征表明其为高清洁度动力用煤;同时还具有中高挥发分、较高氢碳原子比、焦油产率较低（普遍<7%）及富惰质组等特征表明不适于直接液化用或提取煤焦油。无黏结性、较低水分产率、较高的与二氧化碳反应性（950℃）、煤灰熔融温度,表明其适于气化,且以水煤浆气流床和干煤粉气流床为宜。综合认为研究区煤炭资源的清洁高效利用方式为动力用煤,气化用煤及以气化为基础的间接液化用煤。 相似文献
19.
塔里木盆地寒武-奥陶系白云岩结构构造类型及其形成机理 总被引：10，自引：4，他引：6
塔里木盆地寒武-奥陶系白云岩度大、分布广,是重要的油气储集层.根据岩石学研究并结合地球化学特征将其分为4类,其特点如下:(1)泥晶-粉晶白云岩,白云石晶体小、晶形差,有序度在4类中最低(0.73);Na、K、Sr含量在4类中最高;δ13C值及Z值较高,分别为-0.94‰、122.3;Fe、Mn含量较低;阴极发光为亮桔红色;常呈纹层状,具暴露及成化标志.这些特征表明其结晶较快,形成环境蒸发强烈、盐度较高、氧化性较强,是在萨布哈环境中由浓缩海水发生白云石化所形成.(2)藻纹层白云岩,白云石晶体小,晶形较好,有序度较高(0.85);藻纹层基本保留了其原始微细结构;Na、K、Sr含量较低:δC值在4类中最高,平均为-0.50‰;含有较多黄铁矿.这些特征说明其可能形成于成岩作用的稍早期阶段且其成因与藻类活动密切相关,成岩环境盐度较低,可能是在藻类作用下,由富藻层浓集的镁与残留海水在浅埋藏环境中共同作用所形成.(3)雾心亮边白云岩,白云石普遍具雾心亮边结构,雾心含少量包裹体及灰质残余,亮边则少见或无;阴极发光下,雾心发亮桔黄色光,亮边发光暗或不发光;局部见此类白云石;呈星散状分布于亮晶颗粒灰岩或泥晶灰岩中;白云石晶体较大,晶形较好.此类白云岩的δ13C及Z值在4类中最低,K、Na、Sr、Fe含量相对较低,Mn含量最高;有序度较高,均值为0.83.这些特征表明此类白云岩中白云石的雾心可能是在早期浅埋藏环境中,由富镁孔隙水交代周围灰质所形成;亮边则形成于埋藏较深的环境,其所需镁可能来源于粘土矿物的转化.(4)重结晶白云岩:白云石晶体粗大且污浊,接触紧密;局部见白云石晶体具环带结构,局部见颗粒幻影结构;阴极发光较暗;Fe含量在4类中最高,Mn含量较高;有序度最高,平均为0.95;包裹体均一温度平均为110.2℃.这些特征表明其可能是在还原性较强的深埋藏环境中,由早期形成的白云岩经较强的重结晶作用所形成. 相似文献