Trace elements in the Goze Delchev coal deposit, Bulgaria

The geochemistry of trace elements in the underground and open-pit mine of the Goze Delchev subbituminous coal deposit have been studied. The coals in both mines are highly enriched in W, Ge and Be, and at less extent in As, Mn and Y as compared with the world-wide Clarkes for subbituminous coals. Ni and Ti are also enhanced in the underground coals, and Zr, Cr and Mo in the open-pit mine coals.Characteristic for the trace element contents in the deposit is a regular variation with depth. The following patterns were distinguished for profile I: a — the element content decreases from the bottom to the top of the bed paralleling ash distribution (Fe, Co, As, Sb, V, Y, Mo, Cs, REE, Hf, Ta, Th, P and Au); b — Ge and W are enriched in the near-bottom and near-top coals; c — in the middle part of the bed the content of K and Rb is maximal, while that of U is slightly enriched; d — Ba content decreases from the top to the bottom of the bed. In profile II, W and Be contents decrease from the bottom to the top. The near-bottom, and especially the near-roof samples of profile IV are highly enriched in Ge, while for W the highest is the content of the near-bottom sample.Ge, Be, As, Mn, Cl and Br are mainly organically associated. The organic affiliation is still strong for Co, B, Sr, Ba, Sb, U, Th, Mo, La, Ce, Sm, Tb and Yb in the underground coals, and Fe, Co, Na, W, Sr, Y and Ag in the coals from the open-pit mine. K, Rb, Ti, Zr, Hf and Ta are of dominant inorganic affinity. The chalcophile and siderophile elements correlate positively with Fe and each other and may be bound partly with pyrite or other sulphides and iron containing minerals.Compared statistically by the t-criteria, the elements Na, Li, Cu, Zn, Pb, Cr, Ni, Co, Mo, Fe and Be are of higher content in the open-pit mine. Tungsten is the only element of higher concentration in the underground mine. The contents of Ge, As, Sr, V, Mn, Y, Zr and P are not statistically different in both mines.It was supposed that there were multiple sources of the trace elements in the deposit. The source of the highly enriched elements (W, Ge, Be, and As) most probably were the thermal waters in the source area. The contemporary mineral springs are of high content of these elements. Another source were the hosting Mesta volcanic rocks, which are enriched in Sb, Mo, Hf, U, Th, As, Li and Rb. Some of the volcanics were hydrothermally altered and enriched or depleted of many elements. Thus, the hydrothermal solutions were also suppliers of elements for the coals. It is obvious that the contents, distribution and paragenesis, of the trace elements in both Goze Delchev coals reflect the geochemical specialization of the source area, including rocks, paleo- and contemporary thermal waters.     

Mineral and inorganic chemical composition of the Pernik coal, Bulgaria

The mineral and inorganic chemical composition of five types of samples from the Pernik subbituminous coals and their products generated from the Pernik preparation plant were studied. They include feed coal, low-grade coal, high-grade coal, coal slime, and host rock. The mineral matter of the coals contains 44 species that belong mainly to silicates, carbonates, sulphates, sulphides, and oxides/hydroxides, and to a lesser extent, chlorides, biogenic minerals, and organic minerals. The detrital minerals are quartz, kaolinite, micas, feldspars, magnetite, cristobalite, spessartine, and amphibole. The authigenic minerals include various sulphides, silicates, oxihydroxides, sulphates, and carbonates. Several stages and substages of formation were identified during the syngenetic and epigenetic mineral precipitations of these coals. The authigenic minerals show the greatest diversity of mineral species as the epigenetic mineralization (mostly sulphides, carbonates, and sulphates) dominates qualitatively and quantitatively. The epigenetic mineralization was a result of complex processes occurring mostly during the late development of the Pernik basin. These processes indicate intensive tectonic, hydrothermal and volcanic activities accompanied by a change from fresh to marine sedimentation environment. Thermally altered organic matter due to some of the above processes was also identified in the basin. Most of the trace elements in the Pernik coals (Mo, Be, S, Zr, Y, Cl, Ba, Sc, Ga, Ag, V, P, Br, Ni, Co, Pb, Ca, and Ti) show an affinity to OM and phases intimately associated with OM. Some of the trace elements (Sr, Ti, Mn, Ba, Pb, Cu, Zn, Co, Cr, Ni, As, Ag, Yb, Sn, Ga, Ge, etc.) are impurities in authigenic and accessory minerals, while other trace elements (La, Ba, Cu, Ce, Sb, Bi, Zn, Pb, Cd, Nd, etc.) occur as discrete phases. Elements such as Sc, Be, Y, Ba, V, Zr, S, Mo, Ti, and Ga exceed Clarke concentrations in all of the coal types studied. It was also found that a number of elements in the Pernik coals (F, V, As, Pb, Mo, Li, Sr, Ti, Ga, Ni, Ge, Cr, Mn, etc.) reveal mobility in water and could have some environmental concerns.     

Concentration and distribution of elements in Late Permian coals from western Guizhou Province,China

With the aim of better understanding geochemistry of coal, 71 Late Permian whole-seam coal channel samples from western Guizhou Province, Southwest China were studied and 57 elements in them were determined. The contents of Al, Ca, Co, Cr, Cu, Fe, Ga, Hf, K, Li, Mn, Mo, Nb, Ni, Sn, Ta, Ti, Th, U, V, Zr, and REEs in the Late Permian coals from western Guizhou Province are higher than the arithmetic means for the corresponding elements in the US coals, whereas As, Ba, Br, F, Hg, P, Se, and Tl are lower. Compared to common Chinese coals, the contents of Co, Cr, Cu, Ga, Hf, Li, Mn, Mo, Ni, Sc, Sn, Ti, U, V, Zn, and Zr in western Guizhou coals are higher, and As, F, Hg, Rb, Sb, Tl, and W are lower. Five groups of elements may be classified according to their mode of occurrence in coal: The first two, Group A, Tm–Yb–Lu–Y–Er–Ho–Dy–Tb–Ce–La–Nd–Pr–Gd–Sm, and Group B, As–Sr–K–Rb–Ba–F–Ash–Si–Sn–Ga–Hf–Al–Ta–Zr–Be–Th–Na, have high positive correlation coefficients with ash yield and they show mainly inorganic affinity. Some elements from Group B, such as Ba, Be, Ga, Hf, and Th, are also characterized by significant aluminosilicate affinity. In addition, arsenic also exhibits high sulfide affinity (r_S–Fe>0.5). The elements, which have negative or lower positive correlation coefficients with ash yield (with exceptions of Bi, Cs, Nb, Mn, Se, and Ti), are grouped in other four associations: Group C, Cr–V–Mo–U–Cd–Tl; Group D, Hg–Li–Sc–Ti–Eu–Nb–Cs–W; Group E, Bi–Sb; and Group F, Co–Ni–Cu–Pb–Zn–Mg–Se–Ca–Mn–S–Fe. The correlation coefficients of some elements, including Co, Cr, Cu, Fe, Hg, Li, Mo, Ni, P, S, Sc, U, V, and Zn, with ash yield are below the statistically significant value. Only Cr and Cu are negatively correlated to ash yield (−0.07 and −0.01, respectively), showing intermediate (organic and inorganic) affinity. Manganese and Fe are characterized by carbonate affinity probably due to high content of epigenetic veined ankerite in some coals. Phosphorus has low correlation coefficients with any other elements and is not included in these six associations. There are five possible genetic types of enrichment of elements in coal from western Guizhou Province: source rock, volcanic ash, low-temperature hydrothermal fluid, groundwater, and magmatic hydrothermal inputs.     

Characterization of trace elements in sulphur-rich Late Permian coals in the Heshan coal field,Guangxi, South China

The concentration of trace elements and their distribution in the late Permian coal in the Heshan coal field, Guangxi Autonomous Region, were analysed in this paper. The late Permian coal of the Heshan mining district was developed in a low energy and shallow, confined carbonate platform. Heshan coal is a low volatile bituminous coal characterized by a high sulphur content, ranging between 2.0% and 8.2%. Compared with the worldwide average content of the trace elements in coal, the content of some trace element in the study coal is markedly high (Bi, Ce, Cr, Cs, Cu, Ga, Hf, Sr, Ta, Th, U, V, W, Y, Zr, La, Mo, Nb and Sc).The trace element associations were investigated by means of intracorrelation analysis. Some elements, such as Cl, F and Sr are found in coal in association with the carbonate minerals. V, Cr, Zn, Mo, Ni and As contents in coal vary significantly amongst the coal samples. They are mainly concentrated in the lower part of the coal #4 upper of Suhe and Lilan mines and the coal #4 lower of Dong mine, and these possibly occurring in minerals such as arsenide and sulphide. The content of U in Heshan coal is high and is mainly concentrated at the upper and the lower parts of the coal seam and it is associated with mineral assemblages with Ba, Mo, V, Ni, Zn, Rb and Cr. Furthermore, La and Ce are highly correlated with those found in phosphate minerals and Pb, Sc, Ga, Th, Y and Sn to those in aluminosilicate minerals. The enrichment of some elements such as V, Cr, Zn, Mo, Ni, Rb as well as total sulphur and iron in the lower part of most coal seams might be associated with the formation of soil horizon before the accumulation of peat in the basin. Some other elements such as Cl, F, Sr and Ca are locally concentrated in the top of specific coal seams as a result of the leaching from overlying carbonates.     

辽宁北票地区煤中微量元素研究

对辽宁北票地区煤中微量元素进行了研究 ,将研究区煤中微量元素的平均质量分数与世界范围煤的微量元素的平均质量分数进行比较 ,发现北票煤中的Cr、Co、Ni、As、Sr、Y、Zr、Ba、Ta、Sc具有较高的富集 ,而Sn、U具有较低的富集 ,这种差异可能主要与聚煤区域的地球化学背景有关。计算了微量元素之间的相关系数 ,得出北票地区煤中稀土元素总量较世界范围稀土元素总量的平均值偏高 ,且煤中稀土元素分布模式十分相似 ,表明在成煤期间陆源物质供应相对稳定。煤中矿物主要为高岭石、石英及方解石及少量的伊利石 ,并对其中的地质成因进行了初步解释。     

山东济宁高硫煤与低硫煤煤层剖面地球化学特征研究

运用电感耦合等离子质谱（ICP-MS）、X射线荧光光谱（XRF）、离子选择电极（ISE）、显微镜光度计和煤化学等方法,对山东济宁矿区的高硫煤（太原组16号煤层）与低硫煤（山西组3上煤层）剖面的煤岩、煤质和煤地球化学特征进行研究。高硫煤中微量元素在垂向上呈现显著的变化规律：（1）Sr含量从煤层底板到顶板呈增高趋势,而Ba含量则相反;因而Sr/Ba比值从下向上呈逐渐变大趋势（0.04～47.7）;（2）Th/U比值从下向上也呈逐渐变大趋势（0.2～37.1）;（3）As含量在煤层顶板石灰岩（26.1μg/g）、透镜状黄铁矿夹层（14.7～19.3μg/g）中较高;（4）V、Cr、Co、Ni、Cu、Pb、Zn等元素在煤层底部和顶部分层中含量较高,而在煤层中部分层中含量较低;（5）Nb、Ta、Zr、Hf、Ga等元素从煤层的底部到顶部呈逐渐降低趋势;（6）煤中稀土元素总量（REE）,除透镜状黄铁矿夹层（第2、4、11分层）外,其它分层（第1、3、5、6、7、8、9、10分层）显示从上往下逐渐增高之规律性。低硫煤中微量元素的分布和垂向变化与高硫煤明显不同：As含量在14个煤分层中都较低（1.03～3.37μg/g）,Sr/Ba比值从下向上变化不大（0.4～2.2）,各个煤分层中稀土元素总量（REE）呈现随灰份含量增高而增高的变化趋势,低硫煤与高硫煤的稀土元素分布模式差别很大。上述研究结果表明济宁矿区高硫煤与低硫煤在地球化学特征上的差别,反映了上石炭统太原组与下二叠统山西组沉积环境和聚煤条件的差别,具有指相意义;太原组16号煤层中富集的硫及有害微量元素,对环境具有潜在危害。     

Geochemistry of environmentally sensitive trace elements in Permian coals from the Huainan coalfield, Anhui, China

To study the geochemical characteristics of 11 environmentally sensitive trace elements in the coals of the Permian Period from the Huainan coalfield, Anhui province, China, borehole samples of 336 coals, two partings, and four roof and floor mudstones were collected from mineable coal seams. Major elements and selected trace elements were determined by inductively coupled plasma optical emission spectrometry (ICP-OES), inductively coupled plasma mass spectrometry (ICP-MS), and hydride generation atomic absorption spectrometry (HAAS). The depositional environment, abundances, distribution, and modes of occurrence of trace elements were investigated. Results show that clay and carbonate minerals are the principal inorganic constituents in the coals. A lower deltaic plain, where fluvial channel systems developed successively, was the likely depositional environment of the Permian coals in the Huainan coalfield. All major elements have wider variation ranges than those of Chinese coals except for Mg and Fe. The contents of Cr, Co, Ni, and Se are higher than their averages for Chinese coals and world coals. Vertical variations of trace elements in different formations are not significant except for B and Ba. Certain roof and partings are distinctly higher in trace elements than underlying coal bench samples. The modes of occurrence of trace elements vary in different coal seams as a result of different coal-forming environments. Vanadium, Cr, and Th are associated with aluminosilicate minerals, Ba with carbonate minerals, and Cu, Zn, As, Se, and Pb mainly with sulfide minerals.     

Concentration and association of minor and trace elements in Mukah coal from Sarawak, Malaysia, with emphasis on the potentially hazardous trace elements

The ash yield and concentrations of twenty-four minor and trace elements, including twelve potentially hazardous trace elements were determined in Mukah coal from Sarawak, Malaysia. Comparisons made to the Clarke values show that Mukah coal is depleted in Ag, Ba, Be, Cd, Co, Mn, Ni, Se, U, and V. On the other hand, it is enriched in As, Cr, Cu, Pb, Sb, Th, and Zn. Among the trace elements studied, V and Ba are associated predominantly with the clay minerals. Manganese, Cr, Cu, Th, and Ni are mostly bound within the aluminosilicate, sulphide and/or carbonate minerals in varying proportions, though a portion of these elements are also organically bound. Arsenic, Pb and Sb are mostly organically bound, though some of these elements are also associated with the sulphide minerals. Zinc is associated with both the organic and inorganic contents of the coal. Among the potentially hazardous trace elements, Be, Cd, Co, Mn, Ni, Se, and U may be of little or no health and environmental concerns, whereas As, Cr, Pb, Sb and Th require further examination for their potential health and environmental concerns. Of particular concern are the elements As, Pb and Sb, which are mostly organically bound and hence cannot be removed by physical cleaning technologies. They escape during coal combustion, either released as vapours to the atmosphere or are adsorbed onto the fine fly ash particles.     

Geochemistry and Mineralogy of Paleocene Coal from the Padhrar and Darra Adam Khel Coalfields of Pakistan

Pakistan is rich in coal resources, which amount to around 186 billion tons. The Paleocene Padhrar and Darra Adam Khel coalfields are located in the Central Salt Range Punjab Province and the Khyber Pakhtunkhwa Province, Pakistan, respectively. Padhrar coal has not been studied in detail and the Darra Adam Khel coalfields are newly-discovered, so no research has been done, due to security considerations. In this study, an attempt has been made to study the geochemical and mineralogical characteristics of the Padhrar and Darra Adam Khel coals, in order to learn about the coal quality, element enrichment mechanism, sedimentary medium conditions and potentially valuable elements for coal utilization. The Padhrar and Darra Adam Khel coals are low to medium ash, low moisture content, high in volatiles and high total sulfur coal. The vitrinite reflectance in Darra Adam Khel coal is higher than in Padhrar coal, indicating either a greater burial depth or the effects of Himalayan tectonism. The vitrinite content is dominant in the Padhrar and Darra Adam Khel coals, followed by inertinite and liptinite, the major minerals including quartz, clay minerals, calcite and pyrite. The trace elements Ni, As, Be Zn, Ge, Mo, Ta, W, Co and Nb, Sn, Hf, Ta, Pb, Th, Cd, In, Be, V, Cr, Zr, Ag, Li, W and Co are concentrated in some of the Padhrar and Darra Adam Khel coal samples, respectively. The Padhrar coal shows positive Ce, Eu and Gd anomalies, with most of the Darra Adam Khel coal showing negative Ce, Eu and positive Gd anomalies with high LREE. The Al2O3/TiO2 values indicate that the sediment source of the Padhrar and Darra Adam Khel coals is mostly related to intermediate igneous rocks. The Sr/Ba, SiO2 + Al2O3, Fe2O3 + CaO + MgO/SiO2 + Al2O3 and high sulfur content in the Padhrar and Darra Adam Khel coals indicate epithermal and marine water influence with a tidal flat, coal-forming environment and a deltaic coal-forming environment, respectively.     

山西平朔安太堡露天矿9号煤层中的微量元素

使用ＩＣＰ－ＡＥＳ方法对安太堡露天矿９号煤层中的微量元素进行了系统测定,检测出５３种微量元素,将研究煤样的平均微量元素质量分数与世界范围微量元素平均质量分数相比较,煤样中Ｌｉ,Ｇａ,Ｓｒ,Ｚｒ,Ｎｂ,Ｓｎ和Ｔａ具有较高的富集,而Ｃｒ,Ｃｏ,Ｎｉ,Ｇｅ,Ｒｂ,Ｙ,Ｃｓ和Ｂａ具有较低的富集,研究资料表明不同微量元素在垂向剖面上其质量分数具有不同的分布特征。经相关分析表明：（１）与镜质组含量相关的元素有     

电感耦合等离子体质谱-原子荧光光谱法研究上海口岸进口印度尼西亚煤炭微量元素的赋存形态特征

印度尼西亚是我国最大的煤炭进口国,本文应用电感耦合等离子体质谱、原子荧光光谱、直接测汞仪等技术分析了上海口岸31批进口印度尼西亚煤炭中的12种微量元素,结合数理统计方法研究该类煤炭中微量元素的赋存形态。结果表明,进口印尼煤炭中含有高汞煤、三级含砷煤,As、Hg的平均富集系数大于1,其迁移风险值得关注;Be、Cu、Mo、Cd、Sn、Pb含量均低于中国煤和世界煤炭的平均水平,体现出印尼煤炭低灰分的品质特征。12种微量元素和相关项目(灰分和全硫)可划分为3类:第一类归纳为黏土矿物吸附类,包括As、Be、Cr、Co、Ni、Cu、Mo、Cd、Sn、Pb、灰分;第二类归纳为硫铁矿类,包括Hg、全硫;第三类归纳为碳酸盐矿物类,包括Ba。本文研究结果对于指导进口煤炭开发、利用过程中的环境评价和洁净化处理具有一定的参考价值。     

电感耦合等离子体发射光谱-逐级化学提取法研究低硫煤矸石中微量元素的赋存状态及其环境效应

煤矸石是我国堆存量最大的工业固体废物,本文应用电感耦合等离子体发射光谱法、逐级化学提取法和相关性分析研究了淮北临涣矿区低硫煤矸石中10种微量元素的含量及赋存状态,并运用风险评价指数法评价其环境效应。结果表明,低硫煤矸石中Ba、Co、Cr、Mn、Ni、Pb、V含量均高于淮北煤和中国煤均值,Mn、V的富集系数大于1,有一定迁移风险。微量元素主要以残渣态和铁锰氧化物结合态存在,两者质量分数之和为68.87%~92.93%,其中Cd、Co、Cr、Cu、Ni、Pb、Zn赋存于硫化物矿物中,V赋存于黏土矿物中,Mn赋存于碳酸盐矿物和硫化物矿物中。10种微量元素对环境的危害性大小为:MnZnNiPbCdCuBaVCrCo,表明低硫煤矸石堆存过程中活性态Mn对生态环境造成危害的可能性最大,由Mn可能引起的煤矸石山周边地区土壤及水体污染应当重视。     

Trace elements in high-S subbituminous coals from the teruel Mining District, northeast Spain

The elemental composition of high temperature ash (750°C) and forms of S were studied in 25 coal seams from the Escucha Formation (Middle Albian) in the Teruel Mining District, northeast Spain. The principal analytical method was ICP-MS, but ICP-ES was also used in the determination of some trace elements. The analytical data show wide ranges of trace element cotnents among the coal seams studied, even in the vertical profile of a single coal seam. These wide ranges of the trace element concentrations are attributed to both syngenetic and epigenetic processes.When a comparison was made between the average trace element contents of the Teruel Mining District coals, and those of the average content in worldwide coals, the Teruel coals show slightly higher concentrations of Be and U, and lower concentrations of Ba, Cd, Mn, Pb, Sr and Zr. Further, three main groups of trace elements were differentiated on the basis of the inorganic/organic association: (1) trace elements with inorganic affinity; Ba, Ce, Co, Cr, La, Mn, Ni, Rb and Zr. Between these, Ba, Ce, Cr and Rb show a well defined correlation with the clay mineral content, and Co and Ni with pyritic-S content; (2) trace elements with an intermediate (mixed) affinity; As, Cd, Cu, Dy, Er, Eu, Gd, Ge, Ho, Lu, Mo, Nd, Pb, Pr, Sb, Sm, Sr, Tb, Th, Tm, U, Yb and Zn. In this group, As, Cd, Cu, Ge, Mo, Th, U and Zn show a weak trend associated with the mineral matter and Sr with the organic matter; and (3) Be shows an organic affinity. The high mineral matter content (21.3% HTA) of the Teruel coals may account for the great number of elements with inorganic affinity. This classification represents a general trend, but the results show that the affinities of some trace elements (e.g. As, Sb and Zn) may vary from one coal seam to another in the Teruel Mining District.     

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.     

Distribution of environmental sensitive trace elements in the Eocene Sorgun coals, Turkey

The distribution of trace elements in the lower Eocene coal seam mined in the Yeniceltek, Kucukkohne and Ayridam coal mines from the Sorgun Basin was investigated in relation to ash content and maceral composition. The coal seam is mainly composed of huminite. In the present study, 35 samples from five seam sections were collected on the basis of megascopic characteristics. Results were determined using an energy dispersive polarised X-ray fluorescence (EDP-XRF) spectrometer on a whole-coal dry basis. Most of the major and trace elements studied are enriched in high-ash samples, while Ba, Br, Mn and W show relative enrichments in low-ash samples. Most of elements studied, such as Ga, Ce, La, Th, Nb, Rb, Zr, V, Cu, U, Pb, Sb, Cs, Sn, Cr, Se, Y and Zn, are primarily associated with mineral matter (clay minerals). Arsenic and a part of Zn, Se and Sb are probably concentrated in pyrites in the samples. Element concentrations show statistically significant negative correlations with many macerals and positive relationships with only attrinite that is mainly mixed with mineral matter (clay minerals and small quartz grains) in the samples. Nine trace elements (As, Cr, Mn, Ni, Pb, Sb, Se, Th and U), considered as potentially Hazardous Air Pollutants, are present in low to moderate concentrations. The mean values of trace element concentrations display relative enrichments in Se (2.8 ppm), Th (21 ppm) and W (26 ppm) in the investigated samples in comparison with other coals in the world.     

Assessment of elemental content of milled coal,combustion residues,and stack emitted materials: Possible environmental effects for a Canadian pulverized coal-fired power plant

Two monitoring studies were carried out at four-year intervals on a power plant that uses western Canadian subbituminous coal and generates approximately 800 Mw/h of electricity. The distributions of elements of environment concern (As, Hg, Ni, Pb, and Cd) and elements of environmental interest (B, Ba, Be, Cl, Co, Cr, Cu, Mn, Mo, Th, Se, V, U, and Zn) in milled coals, power plant ashes, and emitted materials from the stack were determined using neutron activation analysis (NAA), Inductively Coupled Plasma Emission Spectroscopy (ICPES), and Inductively Coupled Plasma-Mass spectroscopy (ICP-MS) for most elements, Graphite Furnace Atomic Absorption (GFAA) for Pb, and Cold Vapor Atomic Absorption (CVAA) for Hg.The concentrations of most of elements in milled coal are low as compared to world coals and other Canadian milled coals. For example, in both studies mercury is within the lower range of world coal. Bottom ashes from both studies have low concentrations of As, Cd, Hg, Pb, and Zn, as well as low relative enrichment factors (RE) for the same elements, indicating that they were not enriched in the bottom ash. The ESP's remove most of the elements of environmental interest as indicated by their high RE ratios of greater than > 0.7.The rates of input of elements of environmental concern (As, Cd, Hg, Pb and Ni) for this station were 23.65, 1.24, 0.54, 98.2 and 95.2 kg/day, respectively, of which only 0.20, 0.02, 0.31, 0.48 and 0.36 kg/day were emitted from the stack. Thus only a small amount of these elements found in the milled coal was emitted while most were captured in the bottom and the ESP ashes. Nickel has the highest rate of emission (0.48 kg/day) within the elements of environmental concern group. However, the Ni emitted from this station does not belong to the toxic species. The element with the lowest rate of emission is Cd (0.02 kg/day). The total emission of elements of environmental concern is 1.37 kg/day, which is low as compared their ambient concentrations in either rural or urban air. The total rate of emission of B, Ba, Be, Co, Cr, Cu, Mn, Mo, Se, Th, U, V, and Zn is 56.51 kg/day and is mostly comprised of the total emission of Ba (21.73 kg/day) and Zn (19.14 kg/day).     

Concentration and distribution of trace elements in some coals from Northern China

The concentration, distribution and modes of occurrence of trace elements in thirty coals, four floors and two roofs from Northern China were studied. The samples were collected from the major coalfields of Shanxi Province, Shaanxi Province, Inner Mongolian Autonomous Region, and Ningxia Hui Autonomous Region. The concentrations of seventeen potential hazardous trace elements, including Hg, As, Se, Pb, Cd, Br, Ni, Cr, Co, Mo, Mn, Be, Sb, Th, V, U, Zn, and five major elements P, Na, Fe, Al, and Ca in coals were determined.Compared with average concentration of trace elements in Chinese coal, the coals from Northern China contain a higher concentration of Hg, Se, Cd, Mn, and Zn. They may be harmful to the environment in the process of combustion and utilization. Vertical variations of trace elements in three coal seams indicated the distributions of most elements in coal seam are heterogeneous. Based on statistical analyses, trace elements including Mo, Cr, Se, Th, Pb, Sb, V, Be and major elements including Al, P shows an affinity to ash content. In contrast, Br is generally associated with organic matter. Elements As, Ni, Be, Mo, and Fe appear to be associated with pyrite. The concentrations of trace elements weakly correlate either to coal rank or to maceral compositions.     

Modes of Occurrence and Cleaning Potential of Trace Elements in Coals from the Northern Ordos Basin and Shanxi Province, China

Based on the analyses of 43 elements in 16 samples of the raw coal and feed coal collected from the northern Ordos basin and Shanxi Province, the modes of occurrence of these elements were studied using the method of cluster analysis and factor analysis, and the cleaning potential of the hazardous elements relatively enriched in the coals was discussed by analyzing six samples of the cleaned coal from the coal-washing plants and coal cleaning simulation experiments. The results shows that the elements Br and Ba show a strong affinity to the organic matter, Cs, Cd, Pb, Zn and Hg partly to the organic matter, and the other trace elements are mainly associated with the mineral matter. Cs, Mo, P, Pb, Zn and S have positive correlations with the two principal factors, reflecting the complexity of their modes of occurrence. Some elements that were thought to show a faint relationship (Be with S and Sb with carbonates) in other rocks are found to have a strong interrelation in the coals. Clay minerals (mainly k     

The association of major,minor and trace inorganic elements with lignites. III. Trace elements in four lignites and general discussion of all data from this study

Fourteen trace elements (La, Cr, Sc, Y, Yb, Ga, Ni, V, Be, Zr, Ge, Pb, Sn, Ce) have been determined by emission spectroscopy in the ash from 7–17 levels within four early Tertiary lignite seams from Wyoming, Texas and Alabama, and two elements (Cu, Zn) in the acid-soluble and acid-insoluble fractions of the samples by inductively coupled plasma arc emission spectrometry. These elements were also determined in the roof and floor strata enclosing the seams. The concentrations of a number of elements (e.g. Be, V, Cu, Y, Yb) were considerably higher in the coal ash than in the adjacent inorganic layers, and these elements are most probably associated with organic matter as coordination complexes. Several elements (Be, Y, Yb, Ga, Sc) were frequently found to be concentrated near the margins of the seam relative to the main body. One of the seams has a 6 cm “rider” separated from the top of the main seam by 9 cm of clayey sand. Analysis of fractions separated by specific gravity and solubility in acid showed this to be rich in trace elements, of which V, Be, Cu, Ni, Ge, Cr, Y, Yb, Ga and Sc appeared to be partly complexed with organic matter, and Sn and Pb were present only in minerals. The rider evidently acted as an efficient trap for unusually large amounts of many trace elements. Cluster analysis showed that the distributions of elements with depth in three of the seams represent three very distinctly separate populations of data; each seam constitutes a different geochemical problem.In a general discussion of the results of the whole series of three papers, a model describing the incorporation of inorganic components in peats is presented, based on the erosion of rocks by chelating organic acids and other agents, followed by transport in water and trapping of mineral grains and dissolved ions by the organic matter of peat. Inorganic materials in peat thus constitute the principal input of mineral matter into coals. The elements that tend to be enriched near the margins of lignite seams are mostly those that have complexed with organic matter. However, the data on this enrichment from our own and previously published work are quite variable, no doubt depending on the nature and efficiency of transport of the incoming cations.     

Ge-bearing coals of the Luzanovka Graben, Pavlovka brown coal deposit, southern Primorye

Results of the study of a new Ge-bearing area of the Pavlovka brown coal deposit are presented. Ge is accumulated in bed III₂ lying at the bottom of the Late Paleogene-Early Neogene coal-bearing sequence adjacent to the Middle Paleozoic granite basement. The Ge content in coals and coal-bearing rocks varies in different sections from 10 to 200–250 ppm, reaching up to 500–600 ppm in the highest-grade lower part of the bed. The metalliferous area reveals a geochemical zoning: complex Ge-Mo-W anomalies subsequently grades along the depth and strike into Mo-W and W anomalies. Orebodies, like those at many Ge-bearing coal deposits, are concentric in plan and dome-shaped in cross-section. Coals in their central parts, in addition to Ge, W, and Mo, are enriched in U, As, Be, Ag, and Au. Distribution of Ge and other trace elements in the metalliferous sequence and products of gravity separation of Ge-bearing coals is studied. These data indicate that most elements (W, Mo, U, As, Be) concentrated like Ge in the Ge-bearing bed relative to background values are restricted to the organic matter of coals. The electron microscopic study shows that Ge-bearing coals contain native metals and intermetallic compounds in association with carbonates, sulfides, and halogenides. Coal inclusions in the metalliferous and barren areas of the molasse section strongly differ in contents of Ge and associated trace elements. Ge was accumulated in the coals in the course of the interaction of ascending metalliferous solutions with organic matter of the buried peat bogs in Late Miocene. The solutions were presumably represented by N₂-bearing thermal waters (contaminated by volcanogenic CO₂) that are typical of granite terranes.