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1.
In the process of combustion of coal organic and inorganic materials in it will undergo a complex variation.Part of thew will become volatiles and,together with coal smoke,enter into atmosphere,some will remain in micro-particulates such as ash and dust and find their way into atmosphere in the form of solid particles,and the rest will be retained in ash and slag.Coal ashes are the residues of organic and inorganic substances in coal left after coal combustion and the compostition of coal ashes in dependent on that of minerals and organic matter in coal.This paper deals with the chemical composition of coal ashes,the distribution of trace elements in them and their petrological characteristics,and also studies the relationship between the yield of coal ashes and the distribution of trace elements.In addition,a preliminary study in also undertaken on the factors that affect the chemical composition of coal ashes.As viewed from the analyses of coal ash samples collected from the Yanzhou mining district,it can be seen clearly that coal ashes from the region studied are composed chiefly of crystalline materials,glassy materials and uncombusted organic matter and the major chemical compositions are SiO2,Al2O3,Fe2O3,and CaO,as well as minor amounts of SO3,PWO5,Na2O,K2O and TiO2.During the combustion of coal,its trace elements will be redistributed and most of them are enriched in coal ashes.At the same time,the concentrations of the trace elements in flying ash are much higher than those of bottom ash,i.e.,with decreasing particle-size of coal ashes their concentrations will become higher and higher.So the contents of trace elements are negatively proportional to the particle-size of coal ashes.There has been found a positive correlation between the trace elements Th.V.Zn,Cu and Pb and the yield of coal ashes while a negative correlation between Cl and the yield of coal ashes. 相似文献
2.
Distribution of forms of sulfur in peats from saline environments in the Florida Everglades 总被引：1，自引：0，他引：1
Although there is published information on the mechanism of sedimentary pyrite formation resulting from bacterial reduction of sulfate, little is known about the distribution of forms of sulfur, including organic, in peats. In order to increase understanding of the geochemistry of sulfur in coals, we have determined distributions of forms of sulfur in five cores of saline peat and one of brackish peat, all from areas near the Shark River and Whitewater Bay in the coastal swamps of south Florida. All concentrations vary widely with depth. Total sulfur concentrations range up to 6% of dry solids. Minor amounts of sulfur are present as H2S, S0, SO42−, and acid-soluble sulfide, but the principal forms are usually pyritic and organic. The ratio, organic/pyritic, is highly variable, but at a majority of levels in a profile is considerably greater than unity. It is inferred that topochemical factors are important in determining the distribution of sulfur forms in any element of volume. 相似文献
3.
Boyang Wang Yong Qin Jian Shen Gang Wang Jiuqing Li 《Journal of the Geological Society of India》2018,92(1):111-119
The formation environment of the main coal seam in Shengli coal mine is analyzed, and the effect of coal ash parameters on the coal-forming environment is mainly discussed according to gray component parameters combined with other coal quality test analysis data. Results show that the hydrodynamic conditions of the main coal during coal accumulation have a general pattern of strong northeast and weak southwest, and lakeside swamp is generally in the retrograde process from south to north. The No.5 coal seam is a water entry cycle, and the No.5lower coal is a water withdrawal cycle. The No.6 thick coal seam is formed in the peat swamp environment where the water is shallow and the groundwater activity is weak. The input of terrestrial debris material was most abundant in the formation period of No.5lower coal, followed by No.5 coal, and that in No.6 coal is the least. Vertically, the peat swamp environment changed from weak reduction to weak oxidation to strong reducing environment. The ash yield was low to high to low from bottom to top. The organic sulfur is the main type of sulfur in the main coal seam. The weaker the hydrodynamic condition, the higher the organic sulfur content in the reduction environment, while lower organic sulfur content in the oxidation environment. The peat swamp water of No.5lower coal is medium alkaline, and the peat swamp water of No.5 and No. 6 coals is weakly alkaline or acidic. 相似文献
4.
《Chemie der Erde / Geochemistry》2017,77(1):147-157
The study was carried out on the Sulejów dam reservoir (Central Poland). Water and sediment samples were collected between February and October 2006. Sulfur compounds in the sediment were chemically extracted and subjected to isotopic analysis.Large variability of SO42− concentration in the water column (from 10.3 to 36.2 mg/dm3) and the isotopic composition of sulfur (δ34S from 2.1 to 5.4‰) was observed. The main identified sources of SO42− were watercourses, surface runoff, and phosphorus fertilizers.Both oxidized sulfur species (SO42−) and its reduced forms were found in sediments. Particular sulfur forms were characterized by large variations in both, concentrations and the isotopic composition of sulfur. SO42− in the sediment and in the water column had different genesis. Bacterial oxidation of organic sulfur and its binding in SO42− were observed in the sediment. Under reducing conditions, oxidized and organic sulfur is converted to H2S which reacted with Fe or other metallic ions leading to metal sulfide precipitation. Monosulfides were shown to have a very low concentration, ranging up to 0.07 mg/g of sediment. The transformation of elemental sulfur from sulfides through their chemical oxidation occurred in the sediment. 相似文献
5.
中国煤中硫的地球化学研究 总被引：16，自引：0，他引：16
燃烧过程中,煤中硫会以硫氧化物等形式释放出来,污染大气以至形成酸雨,对环境造成极大的影响。本文在对中国煤中硫全面分析的基础上．总结并分析了中国煤中硫在不同地区、不同煤层和不同形成环境中的含量与分布规律,阐述煤中硫形成的地质成因和影响因素．以及育机硫、无机硫和元素硫的赋存状态．概述了煤利用过程中硫的转化机理及其对环境的影响．提出了对煤中硫的研究趋势和今后研究方向与热点问题。 相似文献
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The sulfur isotopic composition of the Herrin (No. 6) Coal from several localities in the Illinois Basin was measured. The sediments immediately overlying these coal beds range from marine shales and limestones to non-marine shales. Organic sulfur, disseminated pyrite, and massive pyrite were extracted from hand samples taken in vertical sections.The values from low-sulfur coals (< 0.8% organic sulfur) underlying nonmarine shale were +3.4 to +7.3%0 for organic sulfur, +1.8 to +16.8%0 for massive pyrite, and +3.9 to +23.8%0 for disseminated pyrite. In contrast, the (> 0.8% organic sulfur) underlying marine sediments were more variable: organic sulfur, ?7.7 to +0.5%0, pyrites, ?17.8 to +28.5%0. In both types of coal, organic sulfur is typically enriched in 34S relative to pyritic sulfur.In general, δ 34S values increased from the top to the base of the bed. Vertical and lateral variations in δ 34S are small for organic sulfur but are large for pyritic sulfur. The sulfur content is relatively constant throughout the bed, with organic sulfur content greater than disseminated pyrite content. The results indicate that most of the organic sulfur in high-sulfur coals is derived from post-depositional reactions with a 34S-depleted source. This source is probably related to bacterial reduction of dissolved sulfate in Carboniferous seawater during a marine transgression after peat deposition. The data suggest that sulfate reduction occurred in an open system initially, and then continued in a closed system as sea water penetrated the bed.Organic sulfur in the low-sulfur coals appears to reflect the original plant sulfur, although diagenetic changes in content and isotopic composition of this fraction cannot be ruled out. The wide variability of the δ 34S in pyrite fractions suggests a complex origin involving varying extents of microbial H2S production from sulfate reservoirs of different isotopic compositions. The precipitation of pyrite may have begun soon after deposition and continued throughout the coalification process. 相似文献
8.
Two new methods for analysis of sedimentary sulfur employing sensitive flame photometric detection have been developed and applied to a study of marine, estuarine and freshwater sediments. Volatile organosulfur compounds generated from freeze-dried sediments upon heating in a H2 atmosphere reflect the distribution and extent of degradation of detrital organic matter. Regions of biogeochemical sulfur transformations, as characterized by the presence of SO2 progenitors, sulfite and thiosulfate, are also depicted. Scrubbing of sediment slurries treated with the reducing agent, acidic Cr(II) solution, releases H2S and CH2SH from their metal-complexed forms. CH3SH is a common constituent of marine and estuarine sediments at sub-ppm concentrations. 相似文献
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10.
The peat-forming systems of the Okefenokee Swamp are viewed as modern progenitors of coal. Taxodium and Nymphaea-derived peat-forming systems were characterized in terms of (1) organic fractions and (2) the distribution of organic/inorganic sulfur in each organic fraction (water soluble, benzene/methanol soluble, humin, humic acid, fulvic acid). The humin fraction is the largest organic fraction in both environments, approaching 70% of the total organic matter in the Nymphaea-derived environment. Humin origins are discussed in terms of a humic acid precursor, and undecomposed plant material. It is suggested that each depth of peat represents a diagenetic history of events which the authors believe occurred primarily when the currently buried peat was at the surface. The sulfur content of both peat-forming areas is low (0.23–0.27%); organic sulfur is the dominant sulfur form. Humin contains 50–80% of the total sulfur and of this, 80% is organic sulfur. Ester-sulfate appears to be especially prevalent in the fulvic acid fraction. The sulfur content of freshwater-derived peats is similar in quantity and distribution to that found in low sulfur coals. 相似文献
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Hassan Baioumy 《Chemie der Erde / Geochemistry》2010,70(1):61-67
Jurassic high-sulfur coals from the Maghara area in Egypt were analyzed for the abundance and isotopic composition of different forms of sulfur. Analyses indicated that the sulfur occurs in the form of organic, pyrite, and sulfate forms. Pyrite sulfur represents the major fraction, while sulfate sulfur is minor and could be formed during sample preparation for the analyses.The δ34S CDT values of the organic sulfur are positive ranging between 1.0‰ and 13.5‰ with an average of 9.1‰. Pyrite δ34S values are also positive ranging between 1.5‰ and 15.4‰ with an average of 6.6‰. The high δ34S values of the organic sulfur in the Maghara coals suggest a freshwater origin of the organic components of these coals. The lack of correlation between pyrite and organic sulfur isotopes implies different incorporation mechanisms of sulfur. The high-sulfur contents along with the positive and high δ34S values suggest a marine origin of pyrite sulfur and support the geological interpretation of marine invasion after the peat formation that was responsible for the incorporation of the pyrite sulfur.The occurrence of pyrite as euhedral crystals as well as the high and positive δ34S values of the pyrite sulfur indicates the formation of pyrite during diagenesis as a result of marine water invasion of the preexisting peat in a brackish coastal plain environment. 相似文献
13.
Sedimentary pyrite formation: An update 总被引：1，自引：0，他引：1
Robert A Berner 《Geochimica et cosmochimica acta》1984,48(4):605-615
Sedimentary pyrite formation during early diagenesis is a major process for controlling the oxygen level of the atmosphere and the sulfate concentration in seawater over geologic time. The amount of pyrite that may form in a sediment is limited by the rates of supply of decomposable organic matter, dissolved sulfate, and reactive detrital iron minerals. Organic matter appears to be the major control on pyrite formation in normal (non-euxinic) terrigenous marine sediments where dissolved sulfate and iron minerals are abundant. By contrast, pyrite formation in non-marine, freshwater sediments is severely limited by low concentrations of sulfate and this characteristic can be used to distinguish ancient organic-rich fresh water shales from marine shales. Under marine euxinic conditions sufficient H2S is produced that the dominant control on pyrite formation is the availability of reactive iron minerals.Calculations, based on a sulfur isotope model, indicate that over Phanerozoic time the worldwide average organic carbon-to-pyrite sulfur ratio of sedimentary rocks has varied considerably. High ratios during Permo-Carboniferous time can be explained by a shift of major organic deposition from the oceans to the land which resulted in the formation of vast coal swamps at that time. Low ratios, compared to today, during the early Paleozoic can be explained in terms of a greater abundance of euxinic basins combined with deposition of a more reactive type of organic matter in the remaining oxygenated portions of the ocean. The latter could have been due to lower oceanic oxygen levels and/or a lack of transportation of refractory terrestrial organic matter to the marine environment due to the absence of vascular land plants at that time. 相似文献
14.
Coal mining impacts on water environs around the Barapukuria coal mining area, Dinajpur, Bangladesh 总被引：2，自引：2，他引：0
M. Farhad Howladar 《Environmental Earth Sciences》2013,70(1):215-226
The present research makes an effort towards awareness of the impact of underground coal mining on water environment around the Barapukuria coal mining area, Dinajpur by direct field investigation, questionnaire survey and laboratory analysis. For this research, the three foremost errands have been mulled over which are the water level data analysis for 10 years from 2001 to 2011, ground water major parametric analysis and the questionnaire survey on the availability of ground water before and after coal mining operation. The results of field and laboratory analysis show that the characteristics and concentrations of all the major physical and chemical parameters such as pH, EC, Temperature, HCO3 ?, NO3 ?, SO4 2?, Cl?, Na+, K+, Mg2+, Ca2+ and Fe(total) are still tolerable for all purposes and also within the standard limit. On the other hand, the questionnaire survey and water level data analysis confirm almost similar results regarding the depletion of water level. The water level has depleted more than 5 m from 2001 to 2011. Therefore, currently the availability of ground water is normal in the rainy and winter seasons but is slight problematic in the dry season where ground water was available at all times prior to coal mining in the area. From these scenarios, it is comprehensible that the ground water level moves downwards than earlier because of the excess pumping of water from the mine area. Besides the natural recharge condition is not enough and somewhere breaks off while some of the mines out areas are subsided, consequently the upper part of the water bearing formations (aquifer) loses its porous and permeable properties resulting water recharging problem which is directly responsible for depleting the ground water level over the area. Moreover, the water levels will also decline relative to the location, depth, recharge, and discharge conditions of the mine both aerially and vertically while there is a typical relationship between the depth of mining and static water level which is water levels will decline more as the mine goes deeper. Therefore, taking into account the current ground water condition and the depth of Barapukuria coal mine, this research implied that the water level will deplete more in day coming and the water crisis will be more for future. Thus, this research recommends a sustainable guideline for long-term planning and also suggests that regular monitoring with time to time more detail qualitative and quantitative assessments of water bodies in the area. 相似文献
15.
Hydrous pyrolysis experiments at 200 to 365°C were carried out on a thermally immature organic-rich limestone containing Type-IIS kerogen from the Ghareb Limestone in North Negev, Israel. This work focuses on the thermal behavior of both organic and inorganic sulfur species and the partitioning of their stable sulfur isotopes among organic and inorganic phases generated during hydrous pyrolyses. Most of the sulfur in the rock (85%) is organic sulfur. The most dominant sulfur transformation is cleavage of organic-bound sulfur to form H2S(gas). Up to 70% of this organic sulfur is released as H2S(gas) that is isotopically lighter than the sulfur in the kerogen. Organic sulfur is enriched by up to 2‰ in 34S during thermal maturation compared with the initial δ34S values. The δ34S values of the three main organic fractions (kerogen, bitumen and expelled oil) are within 1‰ of one another. No thermochemical sulfate reduction or sulfate formation was observed during the experiments. The early released sulfur reacted with available iron to form secondary pyrite and is the most 34S depleted phase, which is 21‰ lighter than the bulk organic sulfur. The large isotopic fractionation for the early formed H2S is a result of the system not being in equilibrium. As partial pressure of H2S(gas) increases, retro reactions with the organic sulfur in the closed system may cause isotope exchange and isotopic homogenization. Part of the δ34S-enriched secondary pyrite decomposes above 300°C resulting in a corresponding decrease in the δ34S of the remaining pyrite. These results are relevant to interpreting thermal maturation processes and their effect on kerogen-oil-H2S-pyrite correlations. In particular, the use of pyrite-kerogen δ34S relations in reconstructing diagenetic conditions of thermally mature rocks is questionable because formation of secondary pyrite during thermal maturation can mask the isotopic signature and quantity of the original diagenetic pyrite. The main transformations of kerogen to bitumen and bitumen to oil can be recorded by using both sulfur content and δ34S of each phase including the H2S(gas). H2S generated in association with oil should be isotopically lighter or similar to oil. It is concluded that small isotopic differentiation obtained between organic and inorganic sulfur species suggests closed-system conditions. Conversely, open-system conditions may cause significant isotopic discrimination between the oil and its source kerogen. The magnitude of this discrimination is suggested to be highly dependent on the availability of iron in a source rock resulting in secondary formation of pyrite. 相似文献
16.
煤中微量元素研究进展 总被引：30，自引：3，他引：30
煤炭是我国的主要能源，在煤炭开采、运输、洗选、淋溶（滤）、燃烧等其它加工利用过程中，煤中的微量元素要发生迁移、析出，并入侵到大气、水、土壤和生态环境中，最终影响人类生存和生活环境。煤中微量元素十分重要，是因为它们与环境问题、动、植物及人类健康密切相关。在研究微量元素时必须考虑微量元素的性质及毒性，它们主要依靠其含量、种类、存在形式、pH值、氧化-还原条件及其它因素。在全面综合国内外研究文献的基础上，分析了煤中微量元素的发现、分布规律、赋存状态、成因机理及微量元素的应用等方面研究的历史、现状，并对今后研究的重点内容和发展方向进行了较为详细的论述和分析，并指出在进一步深入研究煤中微量元素地球化学的基础上，加强微量元素环境学方面的研究是今后煤中微量元素环境地球化学研究的重要内容。 相似文献
17.
系统采集淮北卧龙湖煤矿岩浆蚀变煤层中岩浆岩、煤及顶底板岩石样品,测试分析了样品中汞、灰分、挥发分、水
分以及各形态硫的含量,探讨了岩浆蚀变煤层中汞的分布与赋存特征。结果表明：（1） 岩浆侵入导致煤中灰分升高,挥发
分降低,煤中硫主要以黄铁矿硫和有机硫存在;（2） 岩浆侵入导致煤中汞的富集,卧龙湖煤矿岩浆蚀变煤层中汞的平均含
量高达0.23×10-6,是华北石炭-二叠纪煤、中国煤以及美国煤中汞的平均含量的1.4 倍,1.2 倍和1.3 倍;（3） 煤中汞的含量
随离岩浆侵入体距离增大有逐渐降低的趋势,但在煤岩接触带附近,汞在岩浆侵入体上方和下方的煤中呈现不同的分布特
征;（4） 煤中的汞主要以无机结合态的形式存在,且大部分赋存在煤中的黄铁矿中,同时亦存在与有机硫结合的汞。岩浆
热液对煤层的侵入,导致煤质以及煤中汞的含量和赋存方式发生了显著变化。 相似文献
18.
Yaofa Jiang Erika R. Elswick Maria Mastalerz 《International Journal of Coal Geology》2008,73(3-4):273-284
Sulfur occurs in multiple mineral forms in coals, and its fate in coal combustion is still not well understood. The sulfur isotopic composition of coal from two coal mines in Indiana and fly ash from two power plants that use these coals were studied using geological and geochemical methods. The two coal beds are Middle Pennsylvanian in age; one seam is the low-sulfur (< 1%) Danville Coal Member of the Dugger Formation and the other is the high-sulfur (> 5%) Springfield Coal Member of the Petersburg Formation. Both seams have ash contents of approximately 11%. Fly-ash samples were collected at various points in the ash-collection system in the two plants. The results show notable difference in δ34S for sulfur species within and between the low-sulfur and high-sulfur coal. The δ34S values for all sulfur species are exclusively positive in the low-sulfur Danville coal, whereas the δ34S values for sulfate, pyritic, and organic sulfur are both positive and negative in the high-sulfur Springfield coal. Each coal exhibits a distinct pattern of stratigraphic variation in sulfur isotopic composition. Overall, the δ34S for sulfur species values increase up the section in the low-sulfur Danville coal, whereas they show a decrease up the vertical section in the high-sulfur Springfield coal. Based on the evolution of δ34S for sulfur species, it is suggested that there was influence of seawater on peat swamp, with two marine incursions occurring during peat accumulation of the high-sulfur Springfield coal. Therefore, bacterial sulfate reduction played a key role in converting sulfate into hydrogen sulfide, sulfide minerals, and elemental sulfur. The differences in δ34S between sulfate sulfur and pyritic sulfur is very small between individual benches of both coals, implying that some oxidation occurred during deposition or postdeposition.The δ34S values for fly ash from the high-sulfur Springfield coal (averaging 9.7‰) are greatly enriched in 34S relative to those in the parent coal (averaging 2.2‰). This indicates a fractionation of sulfur isotopes during high-sulfur coal combustion. By contrast, the δ34S values for fly-ash samples from the low-sulfur Danville coal average 10.2‰, only slightly enriched in 34S relative to those from the parent coal (average 7.5‰). The δ34S values for bulk S determined directly from the fly-ash samples show close correspondence with the δ34S values for SO4− 2 leached from the fly ash in the low-sulfur coal, suggesting that the transition from pyrite to sulfate occurred via high-temperature oxidation during coal combustion. 相似文献
19.
Geochemistry of Sulfur and Hazardous Elements in Late Paleozoic Coals and Partings from Taozao Coalfield, Shandong Province, China 总被引：1，自引：0，他引：1
Huang Wenhui Che Yao Yang Qi Tang Dazhen Energy Resource Department China University of Geosciences Beijing China Zhao Zhigen Tang Xiuyi Anhui University of Science Technology Huainan China 《中国地质大学学报(英文版)》2004,15(1):15-22
Intermsoftheharmfulmattersincoalandcoalminingwastes,thefirstisabouthazardouselements ,theotherin cludessulfurandhazardousorganicmatter.Muchresearchontracetoxicelementsandtheirimpactsonenvironmenthasbeeninvestigatedinmanycountries (Goodarzi,1995 ;Finkelman ,1994 ;Chouetal.,1982 ) .Althoughthere searchconcerningthisaspectwasstartedmuchlaterinChi na ,manystudieshavebeenstrengthenedsince 1980 ,andmuchprogresshasbeenmade ,alargenumberofdatahavebeencollected ,andthecomparisonshavebeenmadeforthedata… 相似文献
20.
Timothy R Filley Katherine H FreemanRick T Wilkin Patrick G Hatcher 《Geochimica et cosmochimica acta》2002,66(6):937-954
The distribution and quantity of organic sulfur and iron sulfur species were determined in the Holocene sediments from Mud Lake, Florida. The sediments of this shallow, sinkhole lake are characterized by high sulfur and organic carbon contents as well as active sulfate reduction. They record a shift from a basal peat (below 2 m) comprised of water lily-dominated organic matter to the present cyanobacterial/algal-dominated lake deposit (upper 1 m). This shift in depositional environment and subsequent organic matter source was accompanied by variation in the amount of reactive iron delivered to the sediments, which in turn influenced the type and extent of organic matter sulfurization. Extractable intramolecular organic sulfur is principally found as C25 highly branched isoprenoid (HBI) thiolanes. Extractable polysulfide-linked lipids, determined by selective chemical cleavage with MeLi/MeI and analyzed as methylthioethers (MTE), are dominated by n-alkanes with sulfur attachments at position 1 and 2, as well as lower amounts of C25 HBI-MTE. The δ13C values and carbon-chain length distribution of both series of n-alkylMTE indicate that they are derived from distinct biological precursors. Among the n-alkylMTE with sulfur attachment at position 1 there are three homologous series: one saturated and two with both cis and trans enethiol isomers. The identification of the enethiol in the sulfur-linked macromolecules indicates that n-alkylaldehydes are precursors lipids. The intervals of high concentration of bulk organic sulfur and sulfurized lipids coincide with the intervals of high mineral sulfur content (acid volatile sulfide and chromium reducible sulfur). We suggest that the main control on the enhanced addition of sulfur to the organic matter in Mud Lake was the increased formation of polysulfides during the reduction of iron hydroxides and the subsequent reaction of those polysulfides with mildly oxidized sedimentary organic matter. 相似文献