Petrologic and geochemical characteristics of Seam 9-3 and Seam 2, Xingtai Coalfield, Northern China

Six samples of Carboniferous (Mississippian–Pennsylvanian) coal (Seam 9-3) and 11 samples of Permian coal (Seam 2) from the Xingtai Coalfield were studied by petrological and organic geochemical methods. Both seams show different petrological and geochemical compositions. In Seam 9-3 of the Carboniferous age, the predominant maceral is vitrinite (83%) whereas in Seam 2 of Permian age, inertinite predominates (45%). “Barkinite” was found with an average content 1% only in Seam 2. Sixty-four different aromatic compounds were identified by gas chromatography (GC)/mass spectrometry (MS) analysis of solvent extracts (Extr) of both seams. Abundant polyaromatic sulfur hydrocarbons (PASH) were determined in coal samples from Seam 9-3, while they are very low in samples from Seam 2. 1,2,5-Trimethylnaphthalene and 1,2,5,6-tetramethylnaphthalene contents are much higher in Seam 2, while 2-methylfluorene contents are higher in Seam 9-3. Cadalene was found in Seam 2 with a high content of 94 mg/kg coal but was not detected in samples from Seam 9-3. This might indicate a different floral contribution to the sedimentary organic matter. All petrologic and geochemical results indicate that Seam 2 formed in a more oxidized environment compared with Seam 9-3.     

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.     

Clausthalite in coal

A lead selenide mineral, tentatively identified as clausthalite (PbSe) based on optical microscopy, scanning electron microscopy with energy-dispersive X-ray (EDAX), electron microprobe, and scanning proton microprobe (SPM), has been described in a number of coals. While clausthalite has been mentioned as a possible source of Se in coal, it is present in such small quantities and sizes, that the mineral identification has not been absolutely confirmed. The mineral specimens examined in this study would contribute, not only to the Pb and Se concentrations in the coal, but also, in at least one case, to Hg concentrations.     

山西阳泉矿区含煤岩系沉积环境及聚煤规律探讨

阳泉矿区位于山西东部,沁水盆地东北部边缘,是我国主要煤炭基地之一。煤炭资源十分丰富。矿区面积约275km2,含煤地层为石炭二叠系。 一、含煤岩系的岩矿特征 本区含煤岩系主要由太原组和山西组组成。     

Further Information of the Associated Li Deposits in the No.6 Coal Seam at Jungar Coalfield,Inner Mongolia,Northern China

Total 138 coal samples and 14 parting samples were taken from the No. 6 Seam of the Jungar Coalfield, Inner Mongolia. These samples were analysed by optical microscopy, sequential chemical extraction procedure (SCEP), inductively coupled plasma mass spectrometry (ICP-MS), X-ray powder diffraction (XRD), and scanning electron microscope in conjunction with an energy-dispersive X-ray spectrometer (SEM-EDX) analysis. The results indicate that the Li contents have reached the industrial grade of the coal associated Li deposit, and the total Li reserves have reached 2406600 tons, that is, 5157000 tons Li2O in the No. 6 seam in the Jungar Coalfield. The sequential chemical extraction procedure results suggest that the Li concentration is mainly related to inorganic matter. The minerals in the coals consist of kaolinite, boehmite, chlorite-group mineral, quartz, calcite, pyrite, siderite and amorphous clay material. Some Li could be absorbed by clay minerals in the Li-bearing coal seam. The chlorite phase?could be?most likely the host for a part of Li. The Yinshan Oldland should be the most possible source of Li of the coal.     

The lateral and vertical reflectance and petrological variation of a heat-affected bituminous coal seam from southeastern British Columbia, Canada

Thermally altered pods of coal of very high rank have been observed in a high-volatile-bituminous coal seam in the eastern side of Eagle Mountain, Elk Valley Coalfield, British Columbia. Rank changes have been measured over a strike distance of 7.5 m from 1.24% to 7.1% R_{o max}, corresponding to a rank gradient of 0.78% R_om⁻¹.Petrologically, unaltered to extremely altered vitrinite showing nongranular (basic) anisotropy, mosaic-textured liptinite and pyrolytic carbon are the most abundant components. The limited presence of mosaic on vitrinite is an indication that the coal seam may have been weathered prior to being heat-affected.Evidence points to localized temperatures as high as 1,000°C, which could have been caused by a lightning strike. The eastern side of Eagle Mountain has experienced higher temperatures than the western side, and it appears that the heat ‘front’ and zone of alteration have an irregular pattern, pointing to saturation of parts of the coal seam by water.Four types of pyrolytic carbon having distinct morphology, anisotrophy and optical path with increasing temperature were observed. Reflectance of pyrolytic carbon falls within the zone of heat-affected coals, whereas the optical path of heat-affected Seam 15 samples is different from that of fresh coal with increasing rank.Finally, the reflectance of vitrinite in heat-affected coal is higher than the reflectance of vitrinite in carbonaceous shale in the Seam 15 section.     

K-rich titanate from the Jharia ultrapotassic rock, Gondwana coal fields, eastern India, and its petrological significance

We report a rare accessory groundmass mineral of K-rich titanate, having a composition close to that of potassium triskaidecatitanate (K₂Ti₁₃O₂₇), from an underground drill-core sample of ultrapotassic rock from southwestern part of the Jharia coal field in the Damodar valley, at the northern margin of the Singhbhum craton, Eastern India. Potassium triskaidecatitanate is regarded as a typomorphic mineral of orangeites (Group II kimberlites) of Kaapvaal craton, southern Africa, and its occurrence in the Jharia ultrapotassic rock is significant since ultrapotassic suite of rocks elsewhere from the Damodar valley have been recently suggested to be peralkaline lamproites based on mineral-genetic classification. The important role played by a unique geodynamic setting (involving a thinned metasomatised lithospheric mantle and inheritance of an Archaean subduction component) at the northern margin of the Singhbhum craton in deciding the petrological diversity of the early Cretaceous ultrapotassic intrusives from the Damodar valley is highlighted in this study.     

Co-carbonization of selected American coals with commercial additives

Because of the short supply of high-quality coking coals in certain areas of the world, many methods of improving the coking characteristics of poorly coking or noncoking coals have been examined as alternatives to importing more expensive, better quality coals. Co-carbonization, or the addition of coal-derived or petroleum-derived materials to the coal charge prior to carbonization, has been used on a commercial basis in the Japanese coking industry. These additives have been used in both solid and liquid form as binders in coal briquettes or as direct additions to the coal blend.In this study three different coal lithotypes were sampled from each of three United States bituminous coal seams: (1) a marginally coking high-volatile B-rank Illinois No. 6 Seam; (2) a highly fluid, good coking quality, high-volatile A-rank Pittsburgh Seam; and (3) a strongly coking low-volatile Blue Creek Seam. Each lithotype sample was carbonized in small-scale (50 g) charges with each of three additives at 0, 2, 5, and 10% additive by weight. The additives included ASP, an asphalt pitch; KRP, a petroleum residue pitch; and SRC, a solvent-refined coal product. The different lithotypes were sampled to examine the effects of coal type as well as rank. A micro-tumbler test was used to give at least a relative coke-strength value for the cokes produced. In addition, all the cokes produced were examined microscopically to determine the effects of co-carbonization on the coke structure.The Illinois No. 6, Pittsburgh, and Blue Creek Seam coals all showed substantial strength increases when co-carbonized with 2, 5, and 10% of each of the three additives, particularly at the 5 and 10% levels. The SRC appears to be the best additive overall for the three ranks of coal, as judged by its ability to combine with the coal to make a higher strength coke. There appear to be no conclusive coke-strength differences among lithotype samples for any of the three coals, probably because of the small scale of the tests and the relatively small differences in inert maceral content among the lithotypes. Five percent by weight of additive appears to be sufficient, if properly blended with the coal charge, to produce higher strength cokes. This is also probably the maximum economically viable level, particularly in the United States coking industry. Two percent is probably the minimum additive level for adequate mixing on a commercial scale.     

广西合山晚二叠世碳酸盐岩型煤系层序地层分析

广西合山煤田晚二叠世合山组是在浅水碳酸盐台地背景下形成的典型的碳酸盐岩型含煤岩系 ,其沉积环境有滨外陆棚、生物礁、开阔台地、潮坪和泥炭沼泽等。在包括合山组和大隆组在内的整个晚二叠世地层中 ,可以识别出5个层序界面 ,并可根据这些层序界面将区内上二叠统划分为 4个层序。层序 从合山组底面到合山组下段顶部的四 下 煤层底板硅质岩层之底面 ;层序 包括从四 下 煤底板到四 上 煤底板的一套地层 ;层序 为从四 上 煤层底板到二煤层之下铝土质泥岩底板的序列 ;层序 包括从合山组二煤层之下铝土质泥岩底板到大隆组之顶。其中层序 、层序 和层序 厚度在合山煤田范围内变化较大 ,说明受盆地基底沉降作用控制强烈 ,层序 则表现为多次的煤层-石灰岩旋回性 ,并且在合山煤田甚至桂中地区稳定分布 ,说明可能主要受全球海平面变化控制。与滨海平原靠陆一侧的冲积体系的陆源碎屑岩含煤岩系不同 ,陆表海碳酸盐岩型煤系三级层序中的最大海泛带底部以该层序中向上变薄至最薄的一层煤的底面为代表 ,如研究区三 中 煤层底面即为层序 中的最大海泛带底部 ,其下为三级层序中的海侵体系域 ,其上为高位体系域。三级层序中有包含四 上 、三 下 、三 中 、三 上 等煤层为界的 4个四级层序 ,每个四级层序中发育     

Overview of analytical methods for inorganic constituents in coal

Environmental legislation has had significant impact on coal utilization, especially coal combustion for power generation, in limiting emissions of potentially hazardous materials to the environment. For the most part, such emissions derive from the inorganic constituents in coal. However, as such legislation becomes ever more encompassing, it has increased the need to understand better the behavior of the inorganic species in coal processing to ensure, in part, that such legislation is not unduly burdensome. Consequently, it has led to significant development of new models for the behavior of inorganics in coal combustion and a complementary enhancement of many analytical methods for determining inorganics in coal.In this paper, analytical methods for inorganics in coal are reviewed on three fronts: (i) methods for determining elemental concentrations; (ii) methods for determining the mineralogy of coals; and (iii) methods for determining modes of occurrence (speciation) of trace elements in coal. The concept of association with respect to mineral–maceral and mineral–mineral occurrences is also discussed. Where possible, comparison of different analysis methods has been made by reference to data on well-characterized suites of coals, such as the Argonne premium coal samples.Incremental enhancements will continue to be made in analytical methods for elemental concentrations; however, major improvements are needed in the other two areas. There is a great need to verify and corroborate by direct speciation methods, the many inferences made by indirect methods regarding trace element speciation. Also, improvements in the measurement of mineral association and its integration into the coal mineral analysis by means of the computer-controlled scanning electron microscopy (CCSEM) would be a significant advance. Accurate determinations of both association and coal mineralogy would lead to significant and much-needed refinements of models for the behavior of inorganics in both coal cleaning processes and coal combustion.     

黄县盆地褐煤与油页岩的泥炭沼泽类型分析

对黄县第三纪褐煤与油页岩共生盆地中煤₁和油₁的煤岩学特征及煤相参数特征的分析表明,黄县盆地煤₁形成于较深覆水的森林沼泽,油₁形成于湖泊沼泽,而海水侵入控制着盆地的覆水变化,进而影响了植物群落的演化与更叠。      

The occurrence of anthracites in an area characterized by lower rank coals in the Upper Silesian Coal Basin of Poland

The results of petrographical-geological and chemical examinations on anthracites, semianthracites and medium-low volatile bituminous coals from Jastrzebie in the Upper Silesian Coal Basin of Poland are presented. The coking coals mined in this region exhibit volatile matter V^daf = 18–26%, free swelling index FSI = 3–8 and reflectance R_m = 1.10–1.35% and are inertiniterich coals (I = 25–63%).Coal Seam 504 of the Anticlinal beds (Namurian B) has been affected by thermal metamorphism and contains both coking coals and coals of higher rank. According to the criterion of Polish Standards this coal seam varies from anthracite (V^daf <10%) to semianthracite (V^daf = 10–14%) in rank. The carbon content is slightly lower and the hydrogen content a little higher than those of typical anthracites and semianthracites. The reflectance values (R_m = 1.56–2.62%) are generally lower than the R_m values proposed by the International Committee for Coal Petrology as boundary values for anthracites and bituminous coal. The magnitude of anisotropy and microhardness were also examined. Examinations of optical properties prove that the metamorphism exhibited by the coals is the result of elevated temperature and variable pressure. The analyses of the maceral composition indicate that there is a decrease in the inertinite content in anthracites. Vitrinite exhibits the features of thermally altered coal. The micrinite content shows a little variation. In coking coals, a strongly fluorescing bituminous substance with the optical features of exsudatinite was found. The constructed geological section of Coal Seam 504 shows distinct regular changes in chemical and physical properties as well as the petrographic composition which may be caused by the heat flux of a magma intrusion, not localized so far.     

榆神矿区保水采煤的工程地质背景

论述了榆神矿区煤层上覆红土、风化带基岩、未风化基岩的工程地质特征,认为红土层具有较好的隔水性能,风化带基岩中粘土矿物的含量增加,隔水性能明显增强。2-2煤层上覆基岩为中硬岩石,而且有较多的软弱岩石夹层,煤层开采的冒裂带发育高度相对较小,影响不到第四系萨拉乌苏组含水层底部,具有较好的保水采煤工程地质条件。      

The depositional environment and mineralogical and chemical compositions of high ash brown coal resting on early Tertiary saprock (Schirnding Coal Basin, SE Germany)

The late Tertiary high ash brown coal (R_r=0.26%) of the Schirnding Seam Zone is mainly composed of huminite. The seam is underlain by a thick saprock (mica saprockkaolinite-mica saprock) some tens of meters thick which gradually developed from phyllitic basement rocks and a thin Footwall Series of coarse-grained clastic sediments which, however, occur only in a few places. The roof rocks ‘ Hanging Wall Series' abruptly appear on top of the seam and consist of massive gray mudstones and arenites, intercalated with some tuffites. These Tertiary series were studied in open-pit mines operated for coal and clay and in bore holes. Chemical investigation involved the analyses of TOC, TSC, Ni, Co, Pb, Zn, Ga, Be, V, Cr, U, Th, P, Zr, REE and organic compounds of extracted organic matter (=OM). Early Tertiary chemical weathering was responsible for the monotonous kaolinite-mica-goethite mineral assemblage in the saprock and the footwall series. In the coal-bearing basin a more variegated mineral association including, pyrite, kaolinite, illite, smectite, illite-smectite mixed layers and siderite was brought about by volcanic processes, intrastratal solution set free in course of coalification and early diagenesis and by meteoric waters infiltrating the coal-bearing series from uplifted parts of the basin, which underwent strong oxidation. The environment of deposition is interpreted in terms of peatswamps that were fed by small streams and crevasse splays of a meandering drainage system grading towards the basin margin into a braided stream system on an alluvial fan plain. Strongly fluctuating water levels were responsible for the pronounced cyclicity to be encountered across the coal-bearing series. The processes of element redeposition and element migration in the Schirnding Basin are operative across the interface coal-saprolite (detrital influx of heavy minerals and intrastratal solution, hydrocarbon infiltration and redistribution of organic matter, reworking of duricrusts), in the saprolite proper (weathering leachats) and across the redox boundaries between the Schirnding Seam Zone and the Hanging Wall Series (input of physils and diagenetic alteration) as well as its strongly oxidized stratigraphic equivalents at the basin edge (volcanic influx, intrastratal solutions). Chemical and mineralogical variations across the coal basin which are directly controlled by the variation in the environment of deposition, weathering and groundwater movements may be directly correlated to changes in the saprock due to the immediate contact between coal and bedrock.     

黄县盆地褐煤与油页央的泥炭沼泽类型分析

对黄县第三纪褐煤与油页岩共生盆地中煤1和油1的煤岩学特征及煤相参数特征的分析表明，黄县盆地煤1形成于较深覆水的森林沼泽，油1形成于湖泊沼泽，而海水侵入控制着盆地的覆水变化，进而影响了植物群落的演化与更叠。     

Rare earth element sources and modification in the Lower Kittanning coal bed, Pennsylvania: implications for the origin of coal mineral matter and rare earth element exposure in underground mines

In this study, we examine the variations in rare earth elements (REE) from the Lower Kittanning coal bed of eastern Ohio and western Pennsylvania, USA, in an attempt to understand the factors that control mineral matter deposition and modification in coal, and to evaluate possible REE mixed exposure hazards facing underground mine workers. The results of this study suggest that the Lower Kittanning coal mineral matter is derived primarily from a clastic source similar to that of the shale overburden. While highly charged cations like silicon, aluminum, and titanium remained relatively immobile within the coal mineral matter, iron (primarily as pyrite) was added from nonclastic sources, either during deposition of the coal mire vegetation or subsequent to burial. Other mobile cations (e.g., alkali and alkaline earth elements) appear to have been added to and/or leached from the originally deposited clastic mineral matter. Most of the sulfur in the Lower Kittanning coal bed is bound as FeS₂ in the mineral matter, but a majority of samples contain a small excess of S that is most likely organically bound.In general, the total rare earth element content (TREE) in coal ash is greater than that in the shale overburden. If the primary source of mineral matter is the same as that for the overlying shale, then REE must have been enriched in the coal mineral matter subsequent to deposition. The total rare earth element content of Lower Kittanning coals correlates strongly with Si concentration ([TREE]≈0.0024 [Si]), which provides a threshold for evaluating possible mixed exposure health effects. Chondrite-normalized REE patterns reveal a shale-like light rare earth element (LREE) enrichment for the coal, similar to that of the shale overburden, again suggesting a primarily clastic REE source. However, when normalized to the shale overburden, most of the coal ash samples display a small but distinct heavy rare earth element (HREE) enrichment. We surmise that the HREE were added and/or preferentially retained during epigenesis, possibly associated with groundwater flow through the coal unit, but not necessarily in close association with the addition of iron. At least some of the “excess” HREE could be organically bound within the Lower Kittanning coal.     

鲍店煤矿瓦斯涌出规律分析

利用构造学、沉积学、数学模型分析等方法,简要分析了鲍店煤矿基本地质条件及影响瓦斯赋存的不同因素,论述了研究区影响瓦斯的主要地质因素,包括地质构造、煤层顶板岩性和上覆基岩厚度。总结了鲍店煤矿瓦斯涌出规侓,认为该井田瓦斯涌出量东北部偏高,西南部较低。     

Geochemistry of Mercury in the Permian Tectonically Deformed Coals from Peigou Mine, Xinmi Coalfield, China

As the mercury emitted from coal combustion can lead to serious environmental issues, researchers pay more attention to the content, distribution and occurrence of mercury in coal. In this paper, the content, distribution, and occurrence of mercury in the Permian tectonically deformed coals from Peigou Mine, Xinmi coalfield, Henan Province were investigated. A total of 18 bench samples were taken from No.2-1 coals seam in Peigou Mine, including 15 coal bench samples, two roofs and one floor. The mercury concentration, mineral composition, and main inorganic element content of 18 samples were determined by DMA-80 direct mercury analyzer, XRD, and XRF respectively. The results show that the mercury content ranges from 0.047 ppm to 0.643 ppm, with an average of 0.244 ppm. Though the coal seam has turned into typical tectonically deformed coal by the strong tectonic destruction and plastic deformation, the vertical distribution of mercury has remarkable heterogeneity in coal seam section. By the analysis of correlation between mercury and the main inorganic elements and the mineral composition in coal, we infer that majority of mercury mainly relates to pyrite or kaolinite.     

Environmental impact of mineral transformations undergone during coal combustion

The mineral transformations undergone by high sulfur coal ash were studied. An X-ray diffraction (XRD) experiment was carried out to reproduce experimentally the mineral transformations produced during coal combustion in coal-fired power stations. We have verified that the anhydrite is the main crystalline phase that contains sulfur in the solid combustion waste from 500°C until its decomposition at 1060±10°C. Thus, this calcium sulfate is the main crystalline phase involved in the sulfur retention in the combustion wastes at high temperatures. Therefore, a considerable proportion of the sulfur would not be emitted into the atmosphere at temperatures lower than 1060°C. Taking as a reference the annual coal consumption of the Teruel Mining District (6 million tons), the mean sulfur content and the anhydrite content at 900°C, it was shown that the SO₂ emissions could be reduced by approximately 13 percent (83,000 ton/yr) provided that the combustion temperature was 900°C.