Anomalous Concentrations of Trace Elements in the Spetsugli Germanium Deposit (Pavlovka Brown Coal Deposit,Southern Primorye): Communication 2. Rubidium and Cesium

Data on Rb and Cs concentrations in typical (in terms of Ge content) and Ge-bearing coals, as well as host sedimentary rocks and underlying granites, are reported. It is shown that all Miocene deposits within ore zone are strongly enriched in these elements relative to Ge-barren areas of the deposit. The relative Cs accumulation is several times higher relative to Rb, because Ge-bearing sediments are characterized by anomalously low Rb/Cs ratio (up to 0.9). The average Cs concentration in coals (30.3 ppm) is more than one order of magnitude higher than the typical content in such rocks, while the maximal contents (57.2 ppm) exceed all known highest Cs contents found in solid fuel. Differences in Rb and Cs accumulation were found in the following sequence: coals (A^d < 50%)–coaly siltsones (50% < A^d < 75%)–coal-free and low-coaly silty sandstones and mudstones (A^d > 75%). The Rb content in this sequence increases, while the Cs content reaches maximum (up to 118.1 ppm) in the coaly siltstones. The anomalous Rb and Cs accumulation in Ge-bearing sediments is related to the circulation of volcanogenic thermal solutions, which are enriched in Ge, Rb, and Cs. It is suggested that Rb is mainly sorbed by clayey particles, whereas Cs is concentrated in the organic matter as well. This work presents the first data on high contents and distribution of Rb and Cs in Ge-bearing coals of the Pavlovka deposit. The data obtained make its possible to consider Rb and Cs as new associated elements of Ge mineralization, although their occurrence mode differs from that of Ge.     

Anomalous gold contents in brown coals and peat in the south-eastern region of the Western-Siberian platform

One hundred twenty-two samples of Jurassic and Paleogene brown coals and 1254 peat samples from the south-eastern region of the Western-Siberian platform were analyzed for gold by the neutron-activation method. Mean content of Au in Jurassic coals is 30 ± 8 ppb, in Paleogene coals is 10.6 ± 4.8 ppb, and in peat is 6 ± 1.4 ppb. Concentrations of gold as high as 4.4 ppm were found in coal ash and 0.48 ppm in the peat ash. Coal beds with anomalous gold contents were found at Western-Siberian platform for the first time.Negative correlation between gold and ash yield in coals and peat and highest gold concentrations were found in low-ash and ultra-low-ash coals and peat. Primarily this is due to gold's association with organic matter.For the investigation of mode of occurrence of Au in peat the bitumen, water-soluble and high-hydrolyzed substances, humic acids, cellulose and lignin were extracted from it. It was determined that in peat about 95% of gold is combined with organic matter. Forty to sixty percent of Au is contained in humic acids and the same content is in lignin. Bitumens, water-soluble and high-hydrolyzed substances contain no more than 1% of general gold quantity in peat.The conditions of accumulation of high gold concentrations were considered. The authors suggest that Au accumulation in peat and brown coals and the connection between anomalous gold concentrations and organic matter in low-ash coals and peat can explain a biogenic–sorption mechanism of Au accumulation. The sources of formation of Au high concentration were various Au–Sb, Au–Ag Au–As–Sb deposits that are abundant in the Southern and South-Eastern peripheries of the coal basin.     

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.     

Metalliferous coals: A review of the main genetic and geochemical types

This paper presents a review of the genetic types and geochemical processes that have formed ‘metalliferous’ coals around the world. Primary attention is given to elements in coal that are currently being extracted from coal as raw material (Ge and U) or have, in our opinion, the best chance for such use (REE, Ag, Au, and PGE). Coals with anomalously high concentrations of other metals having potential for economic by-product recovery (Be, Sc, V, Ga, Sb, Cs, Mo, W, and Re) are briefly considered. Original data and a survey of the literature indicate that metalliferous coals are in many coal basins. Ore formation in coal-bearing structures may occur during peat accumulation, during diagenesis of the organic matter, or by epigenesis. Various metals are supplied to sedimentary basins as minerals that are transported by water and wind or as ionic species in surface water and descending and ascending underground water and may be incorporated into peat or coals. The modes of occurrence of metals in the enriched coals are diverse. The data presented in this review indicates that metalliferous coals should be regarded as promising for economic recovery for by-products in the course of coal mining and combustion.     

Scandium in the coals of Northern Asia (Siberia,the Russian Far East,Mongolia, and Kazakhstan)

We present new original data on the geochemistry of scandium in the coals of Asian Russia, Mongolia, and Kazakhstan. In general, the studied coals are enriched in Sc as compared with the average coals worldwide. Coal deposits with abnormally high, up to commercial, Sc contents were detected in different parts of the study area. The factors for the accumulation of Sc in coals have been identified. The Sc contents of the coals depend on the petrologic composition of coal basins (composition of rocks in their framing) and the facies conditions of coal accumulation. We have established the redistribution and partial removal of Sc from a coal seam during coal metamorphism. The distribution of Sc in deposits and coal seams indicates the predominantly hydrogenic mechanism of its anomalous concentration in coals and peats. The accumulation of Sc in the coals and peats is attributed to its leaching out of the coal-bearing rocks and redeposition in a coal (peat) layer with groundwater and underground water enriched in organic acids. The enrichment of coals with Sc requires conditions for the formation of Sc-enriched coal-bearing rocks and conditions for its leaching and transport to the coal seam. Such conditions can be found in the present-day peatland systems of West Siberia and, probably, in ancient basins of peat (coal) accumulation.     

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     

Petrological,geochemical, and mineralogical compositions of the low-Ge coals from the Shengli Coalfield,China: A comparative study with Ge-rich coals and a formation model for coal-hosted Ge ore deposit

To better understand the formation mechanism of coal-hosted Ge ore deposits, this paper reports on the petrological, mineralogical, and geochemical compositions of the low-Ge coals in the Shengli Coalfield (Inner Mongolia, China), using optical microscopy, field emission-scanning electron microscopy, X-ray fluorescence, X-ray diffraction, and inductively coupled plasma mass spectrometry. The samples in the present study closely neighbor the previously-reported Wulantuga coal-hosted Ge ore deposit (both No. 6 Coal). In comparison with the Wulantuga Ge-rich coals, the low-Ge coals of the Shengli field display higher moisture (27.59% on average) and lower pyritic sulfur contents (0.53%). Both the low-Ge and Ge-rich coals are generally high in inertinite, and have varying but relatively low huminite contents. Preservation of fecal pellets as macrinite is notable in both the low-Ge and Ge-rich coals, and the position of the fecal pellets appears to be within tunnels or chambers within the wood. Quartz, kaolinite, pyrite, and gypsum are the major crystalline phases identified in most of the Ge-rich and low-Ge coals, but the low-Ge coals contain significantly less pyrite and are more abundant in non-mineral Ca and Mg. Ca-oxalate of authigenic origin is observed, generally occurring as cell-fillings in the low-Ge coals. Otherwise mineral-free organic matter in the low-Ge coals would be expected to have an inherent ash yield of around 6%, derived from the inorganic elements (mainly non-mineral Ca and Mg) that occur either in the organic matter or as dissolved ions in the pore water and form the sulfate species in low-temperature (oxygen-plasma) ash residues. The highly-elevated trace elements, including Be, Ge, As, Sb, W, Hg, and Tl, that occur in the Ge-rich coals of the Wulantuga deposit, are significantly depleted in the low-Ge coals. Lateral migration of Ge–W- and As–Hg–Sb–Tl-rich solutions through the original peat swamp for the Wulantuga Ge ore deposit has led to significant enrichment of Ge on the margin of the coal basin but decreasing Ge concentrations toward to the inner part of the basin. Such a migration direction is different to those in the previously-reported for the hydrothermal solutions in the Lincang (Yunnan of China) and Spetzugli (Russian Far East) Ge ore deposits, where the solutions migrated vertically from granite to peat along faults and led to a dome-shaped Ge distribution in the relevant coal seam.     

Geochemistry, mineralogy, and technological properties of the main Stephanian (Carboniferous) coal seams from the Puertollano Basin, Spain

This study is focused on the occurrence and distribution of mineral matter and major and trace elements in the high volatile bituminous coal from Puertollano (south-central Spain). The relationship between ash behaviour and inorganic composition, as well as the possible formation of fouling and slagging deposits in boilers during the conversion process, were investigated. The Puertollano coals do not exhibit plastic properties, despite their rank, probably because of their high ash and inertinite contents.The Puertollano coal has medium to low total S content (0.48% to 1.63% db, with a mean of 1.0% db) and is characterised by relatively high contents of Si, Pb, Sb, and Cs. Some elements such as As, Cd, Co, Cr, Cu, Ge, Li, Mn, Ni, W, and Zn are also present in relatively high contents. The enrichment in a number of heavy metals could be attributed to the common sulphide ores occurring near the Puertollano coal deposit.The following trace elements affinities are deduced: (a) sulphide affinity: As, Co, Cd, Cu, Ni, Sb, Tl, and Zn; (b) aluminum–silicate affinity: K, Ti, B, Co, Cr, Cs, Cu Ga, Hf, Li, Nb, Rb, Sn, Ta, Th, V, Zr, and LREE; (c) Carbonate affinity: Ca, Mg, Mn, and B; (d) organic affinity: B.The very high Si levels and the anomalous enrichment in Cs, Ge, Pb, Sb, and Zn shown by the Puertollano coals account for the high contents of these elements in the Puertollano fly ash when compared with the other Spanish coal fly ashes.The chemical composition of the high temperature ash (HTA) is consistent with the trend shown by the ash fusion temperatures (AFT) and also with the predictive indices related to slagging and fouling propensities. Thus, the ash fusion temperatures increase with high values of Al₂O₃ as well as with the decrease in Fe₂O₃, CaO, and MgO.     

Distribution of major, minor and trace elements in Hat Creek Deposit No. 2, British Columbia, Canada

The major-, minor- and trace-element contents of coals from Hat Creek No. 2 deposit, British Columbia, are determined using INAA and inductively coupled plasma emission spectrometry (boron only).

Al, Cr, Fe, Mn and Na were found to be inorganically bound in the coal while As, B and S are associated with the organic fraction of the coal. The rare-earth element concentrations in the coal are variable, however, the LREE/HREE ratio decreases from base to the top of the deposits. Many elements show little variation in concentration with depth; however, the gradual increase of As and S with depth appears to be rank related and indicative of progressive decrease in porosity with increasing rank.

Concentrations of B and Cr are sensitive to the environment of coal deposition, with coal deposited in a freshwater environment (Hat Creek No. 2 deposit), having low B and high Cr compared with more brackish coals.     

Determination of elemental affinities by density fractionation of bulk coal samples from the Chongqing coal district, Southwestern China

The occurrence and distribution of major and trace elements have been investigated in two coal-bearing units in the Chonqing mining district (South China): the Late Permian and Late Triassic coals.The Late Permian coals have higher S contents than the Late Triassic coals due to the fixation of pyrite in marine-influenced coal-forming environments. The occurrence of pyrite accounts for the association of a large number of elements (Fe, S, As, Cd, Co, Cu, Mn, Mo, Ni, Pb, Sb, Se, and Zn) with sulphides, as deduced from the analysis of the density fractions. The marine influence is probably also responsible for the organic association of B. The REEs, Zr, Nb, and Hf, are enriched by a factor of 2–3 with respect to the highest levels fixed for the usual worldwide concentration ranges in coal for these elements. The content of these elements in the Late Permian coal is higher by a factor of 5–10 with respect to the Late Triassic coal. Furthermore, other elements, such as Cu, P, Th, U, V, and Y, are relatively enriched with respect to the common range values, with maximum values higher than the usual range or close to the maximum levels in coal. The content of these elements in the Late Permian coal is higher than the Late Triassic coal. These geochemical enrichments are the consequence of the occurrence, in relatively high levels, of phosphate minerals, such as apatite, xenotime, and monazite, as deduced from the study of the density fractions obtained from the bulk coal.The Late Triassic coal has a low sulphur content with a major organic affinity. The trace element contents are low when compared with worldwide ranges for coal. In this coal, the trace element distribution is governed by clay minerals, carbonate minerals, and to a lesser extent, by organic matter and sulphide minerals.Major differences found between late Permian and Triassic coals are probably related to the source rocks, given that the main source rock of the late Permian epicontinental marine basin is the Emeishan basalt formation, characterised by a high phosphate content.     

Geological and geochemical characteristics of high arsenic coals from endemic arsenosis areas in southwestern Guizhou Province,China

Southwest Guizhou Province is one of the most important areas of disseminated, sediment-hosted-type Au deposits in China and is an important area of coal production. The chemistry of most of the coals in SW Guizhou is similar to those in other parts of China. Their As content is near the Chinese coal average, but some local, small coal mines contain high As coals. The highest As content is up to 3.5 wt.% in the coal. The use of high As coals has caused in excess of 3000 cases of As poisoning in several villages. The high As coals are in the Longtan formation, which is an alternating marine facies and terrestrial facies. The coals are distributed on both sides of faults that parallel the regional anticlinal axis. The As content of coal is higher closer to the fault plane. The As content of coal changes greatly in different coal beds and different locations of the same bed. Geological structures such as anticlines, faults and sedimentary strata control the distribution of high As coals. Small Au deposits as well as Sb, Hg, and Th mineralization, are found near the high As coals. Although some As-bearing minerals such as pyrite, arsenopyrite, realgar (?), As-bearing sulfate, As-bearing clays, and phosphate are found in the high As coals, their contents cannot account for the abundance of As in some coals. Analysis of the coal indicates that As mainly exists in the form of As⁵⁺ and As³⁺, perhaps, combined with organic compounds. The occurrence of such exceptionally high As contents in coal and the fact that the As is dominantly organically associated are unique observations.     

中国煤中硒的环境地球化学

硒是煤中易挥发元素之一。伴随煤炭的开采、利用,煤中硒可能进入环境并引起环境质量的变化,影响生态环境和人体健康。本文在全面综合国内外研究文献的基础上,分析了中国煤中硒在不同省份、不同成煤时代中的含量及分布规律,总结了硒在煤中的赋存状态、形成机理和影响因素,概括了煤在燃烧和淋溶过程中硒的迁移转化及其环境影响,指出中国煤中硒的含量在不同煤田、不同成煤时代及不同变质程度的煤中,含量差别较大,全国平均值约为5.60 mg/kg。     

Arsenic in coal: a review

The review presented covers: (a) historical introduction; (b) some analytical comments; (c) some peculiarities of the As geochemistry in environment; (d) an estimation of coal Clarke value of As; (e) some coals enriched in As; (f) mode of As occurrence in coal; (g) factors influencing the As distribution in coal matter and coal bed; (h) genetic topics; (i) some topics related to environmental impact of As by the coal combustion.The World average As content in coals (coal Clarke of As) for the bituminous coals and lignites are, respectively, 9.0±0.8 and 7.4±1.4 ppm. On an ash basis, these contents are higher: 50±5 and 49±8 ppm, respectively. Therefore, As is a very coalphile element: it has strong affinity to coal matter — organic and (or) inorganic but obligatory authigenic. The coalphile affinity of As is like that for Ge or S.There is strong regional variability of As distribution due to geologic variability of the individual coal basins. For example, bituminous coals in Eastern Germany, Czech Republic and SE China are enriched in As, whereas the coals in South Africa or Australia are very depleted compared to coal Clarke of As. In general, some relationship exists between As content and its mode of occurrence in coals. Typically, at high As content, sulphide sites dominate (pyrite and other more rare sulphides), whereas at low As content, As_org dominates, both being authigenic. A contribution of the terrigenic As (in silicates) is usually minor and of the biogenic As_bio (derived from coal-forming plants) is poorly known.Both organic and inorganic As can exist not only as chemically bound form but also in the sorbed (acid leacheable) arsenate form. With increasing coal rank, sorbed exchangeable arsenate content decreases, with a minimum in the coking coals (German data: the Ruhr coals).Relations of As content in coal to ash yield (or its partitioning in sink–float fractions) and to coal petrographic composition are usually complicated. In most cases, these relations are controlled by main site (form) of As — As_pyr or As_org. If As_pyr dominates, an As accumulation in heavy fractions (or in high-ash coals) is observed, and if As_org dominates, it is enriched in medium-density fractions (or low- and medium-ash coals). Arsenic is in part accumulated in the inertinite vs. vitrinite (As_org ?).There are four genetic types of As accumulation on coal: two epigenetic and two syngenetic: (1) Chinese type—hydrothermal As enrichment, sometimes similar to known Carlin type of As-bearing telethermal gold deposits; (2) Dakota type—hypergene enrichment from ground waters draining As-bearing tufa host rocks; (3) Bulgarian type—As enrichment resulting from As-bearing waters entered coal-forming peat bogs from sulphide deposit aureoles; (4) Turkish type—volcanic input of As in coal-forming peat bog as exhalations, brines and volcanic ash.During coal combustion at power plants, most of the initial As in coal volatilizes into the gaseous phase. At the widely used combustion of pulverized coal, most of As_org, As_pyr and “shielded” As-bearing micromineral phases escape into gaseous and particulate phase and only minor part of As_clay remains in bottom ash. The dominant fraction of escaping As is in fly ash. Because 97–99% of the fly ash is collected by electrostatic precipitators, the atmospheric emission of As (solid phase and gaseous) is usually assumed as rather minor (10–30% from initial As in coal). However, fly ash disposal creates some difficult environmental problems because it is potentially toxic in natural waters and soils. The As leaching rate from ash disposal is greatly controlled by the ash chemistry. In natural environment, As can be readily leached from acid (SiO₂-rich) bituminous coal ashes but can be very difficult from alkali (CaO-rich) lignite ashes.If the As_pyr form dominates, conventional coal cleaning may be an efficient tool for the removing As from coal. However, organic-bound or micromineral arsenic (“shielded” grains of As-bearing sulphides) are not removed by this procedure.Some considerations show that “toxicity threshold” of As content in coal (permissible concentration for industrial utility) may be in the range 100–300 ppm As. However, for different coals (with different proportions of As-forms), and for different combustion procedures, this “threshold” varies.     

济宁煤田煤中氯的分布、赋存及富集因素研究

氯是煤中普遍存在的一种元素, 氯的含量与分布影响着煤的加工与利用.通过对济宁煤田各主要可采煤层中氯含量的分析可知, 研究区属低氯煤层, 氯含量的高低及分布与煤层空间位置、成煤植物、沉积环境和地下水活动等因素有着重要的关系.同时, 对氯在煤中的赋存状态进行了研究, 通过氯与有机显微组分、灰产率等指标的相关性计算, 得出研究区煤中的氯与有机显微组分成正比, 与灰产率成反比, 说明氯主要存在于煤的有机质中, 并且主要是存在于镜质组分的微孔隙中.      

Abundances and modes of occurrence of trace elements in the Çan coals (Miocene), Çanakkale-Turkey

This study presents the concentrations and modes of occurrence of trace elements in 81 coal samples from the Çan basin of northwestern Turkey. The concentration of trace elements in coal were determined by inductively coupled plasma-mass spectrometry and inductively coupled plasma-atomic emission spectrometry. Additionally, traditional coal parameters were studied by proximate, ultimate, X-ray diffraction, and petrographic analyses. Twenty trace elements, including As, B, Ba, Be, Cd, Cu, Co, F, Hg, Mo, Ni, Pb, Sb, Se Sn, Th, Tl, U, V, and Zn, receive much attention due to their related environmental and human health concerns. The Çan coals investigated in this study are lignite to sub-bituminous coal, with a broad range of ash yields and sulphur contents. The trace element concentrations show variety within the coal seams in the basin, and the affinities vary among locations. The concentrations of B, Ba, Be, Cd, Cu, Co, F, Hg, Mo, Ni, Pb, Sb, Se, Sn, Tl, and Zn in Çan coals are within the Swaine's worldwide concentration range, with the exception of As, Th, U, and V. On the other hand, compared with world coals, the Çan basin coals have higher contents of As, B, Cu, Co, Mo, Pb, Th, U, V, and Zn. Based on statistical analyses, most of the trace elements, except for U, show an affinity to ash yield. Elements including As, Cd, Hg, Se, Cu, Mo, Ni, and Zn, show a possible association with pyrite; however, the elements Se, B, and Mo can be have both organic and inorganic associations.     

Petrographic, mineralogy, and geochemistry of coals of Pabedana, Kerman Province, Central Iran

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.     

煤中砷的赋存状态

砷是煤中常见的有害微量元素,由于其丰度较低,定量研究其赋存状态一直很困难。近年来,采用逐级化学提取实验方法对煤中不同赋存状态的砷进行了定量研究,综合分析这些研究可得出以下结论：①煤中砷的赋存状态包括硫化物态砷、有机态砷、砷酸盐态砷、硅酸盐态砷、水溶态和可交换态砷。总体上,硫化物态砷＞有机态砷＞砷酸盐态砷＞硅酸盐态砷＞水溶态和可交换态砷,但在不同的煤样品中,也表现出较大的差异性。②一般而言,煤中大部分砷存在于含砷黄铁矿中,含砷黄铁矿中的砷含量与黄铁矿的成因或类型有关。煤中的砷酸盐态砷主要与铁氧化物和氢氧化物共生;硅酸盐态砷主要进入粘土矿物晶格。③在砷含量较低的煤样品中,有机态砷含量较高,其中在褐煤和低煤级烟煤中,可提取出与腐殖酸和富里酸结合的砷。当前还难以确认有机态砷的化学结构。④贵州特高砷煤中砷的赋存状态较为复杂,在某些样品中与氧结合的有机态砷为主要的赋存状态。     

华南地区晚二叠世煤的稀土元素特征

在华南地区贵州六盘水、江西乐平和湖北黄石矿区以及重庆钟梁山和磨心坡煤矿晚二叠世煤的稀土元素电感耦合等离子质谱分析数据的基础上,系统研究了华南地区煤的稀土元素的质量分数分布特征、赋存特征、配分模式及其地质控制因素.煤的稀土元素质量分数与灰分质量分数呈正相关关系,部分煤样品由于有富稀土元素的重矿物组合的存在而出现稀土元素的异常高值.同一矿区晚二叠世煤的稀土元素配分模式具有一定的相似性,而不同地区晚二叠世煤的稀土元素配分模式则差异较大.煤的沉积环境、煤中无机矿物的组成以及海水的影响是控制煤的稀土元素质量分数及其配分模式的主要地质因素.     

中国煤中有机硫的分布及其成因

对来自全国26个省、市、自治区的290个煤样中有机硫的质量分数测试及研究,发现煤中有机硫质量分数基本分布在0%1.0%范围内。在低硫煤中硫分以有机硫为主,在高硫煤中以无机硫为主。中、高硫煤中,广西、湖南等地区很大一部分煤中硫分以有机硫为主。在所采集的样品中,高有机硫煤(有机硫>1%)均分布在华南、华北两大聚煤区,属于石炭、二叠纪煤。高有机硫煤中有机硫质量分数的变化与变质程度无明显关系。煤炭形成过程中海水作用的影响,是导致煤中有机硫含量偏高的最主要原因。      

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.