准格尔煤田串草圪旦煤矿5号煤中有害元素赋存状态与分布规律

为研究准格尔串草圪旦5号煤微量元素地球化学特征,采用光学显微镜、扫描电子显微镜和X射线衍射(XRD)方法观测煤中矿物组成及形态特征,应用电感耦合等离子质谱morphological feature(ICP-MS)方法测定煤中多种微量元素含量,运用数理统计方法研究微量元素在煤中的赋存特征。结果表明:5号煤中Be、F、U、Hg元素相对富集,含量高于研究区6号煤及华北煤中含量水平。5号煤中F、Se无机亲和性强,Be、As、U为亲有机元素;Hg与硫含量显著正相关。元素在煤中主要以有机结合态、无机结合态和硫化物结合态为主要赋存状态。     

伊犁煤中潜在有害元素的分布及赋存特征

利用电感耦合等离子体原子发射光谱(ICP-AES)、电感耦合等离子体质谱(ICP-MS)和粉末X射线衍射(XRD)对伊犁盆地48个煤样中常微量元素和矿物含量进行测试,重点探讨As,Cd,Cr,Ni,Pb,Se,Be,Co,Mn,Sb,Th和U等12种潜在有害元素分布及赋存特征。结果表明:1伊犁煤中Mn和Co含量均值接近或超过世界煤和中国煤中Mn和Co含量均值,其他元素均低于世界煤和中国煤含量均值,尤其Se和Cd含量在各样品中均低于检测值;2伊犁煤中Be,Cr,As,Pb,Th和U以铝硅酸盐结合态和碳酸盐岩结合态存在,Mn主要以碳酸盐岩结合态存在,Co和Ni在木斯乡煤中主要以有机结合态存在,在其他伊犁煤中主要以铝硅酸盐结合态存在。     

大同煤田北部中侏罗统煤中伴生元素分布特征及其地质意义

为研究大同煤田中侏罗统煤中伴生元素地球化学特征及地质意义,应用电感耦合等离子体质谱（ICP-MS）、X射线衍射法（XRD）、光学电子显微镜和扫描电子显微镜（SEM）等测试方法分析煤田北部9个煤层中伴生元素含量和赋存特征。结果表明:煤中微量元素含量低,其有益元素（Li、Ga）含量均远低于边界品位,不具伴生成矿开发潜力,但2号煤中Co与Zn、9号煤中Tl和11-2号煤中Be等有害元素较为富集,是世界煤平均值的3倍以上,其环境影响值得关注。煤中主要矿物是高岭石与石英,高岭石主要充填在结构镜质体中,指示其同生成因,石英往往具有很好的晶型,指示其自生成因;少量的黄铁矿和方解石充填在显微裂隙中,指示其后生成因;磷灰石与有机质结合。煤中微量元素Ni和Mo可能主要以有机质结合态存在,其他元素主要赋存在无机矿物中,Si主要以石英形式存在,部分Si和Al以及Li、Cr、Ga和Nb存于黏土矿物中,Fe和Mn以及Cd、Zn、Tl赋存于黄铁矿中;Ca和Mg以及Co主要赋存在碳酸盐矿物中;P、Be、Sr和Ba可能存在磷灰石中;Rb赋存在石盐类矿物中。垂向上看,大同组存在2个沉积旋回,每个沉积旋回由下至上,水动力条件逐渐降低,水体由浅到深,陆源碎屑供给越来越少,这2个旋回间可能经历了较强的地质作用。总体看,在成煤期,随沉积作用的进行,聚煤盆地中碎屑物质输入逐渐减少,活性物质逐渐增加。      

涡阳花沟西10号煤中微量元素的有机亲和性

为研究淮北矿区涡阳花沟西勘查区10号煤中微量元素的有机亲和性,共采集10个勘探钻孔煤样品,采用电感耦合等离子质谱仪ICP-MS分析了12种微量元素的含量;应用LECO碳硫分析仪测定了煤的总有机碳TOC,并通过两者的相关关系分析了元素的有机亲和性,结合元素的地球化学特征和煤样XRD物相鉴定结果,通过聚类分析进一步推断元素的赋存状态。结果表明:V、Cr、Co、Ni、Mo、Cd、Sb、Pb和Zn元素含量低于全国均值,没有异常富集,Be、Cu和Tl略高于全国均值;Cd具有较强的有机亲和性,Co、Zn、Be和Cr的有机亲和性较弱,V、Ni、Cu、Mo、Sb、Pb和Tl不具有机亲和性;V、Sb、Cu、Cr、Pb、Co和Ni主要以铝硅酸盐吸附态赋存,Cd主要以有机结合态赋存。      

乌兰图嘎富锗煤中微量元素在不同密度级煤中的分布特征

煤系关键金属的开发利用对于缓解我国战略性矿产资源紧缺具有重要意义。内蒙古胜利煤田乌兰图嘎低阶煤中除富集关键金属Ge以外,同时富集有害元素Be、F、As、Hg、Sb和W,出于对关键金属的提取利用及环境保护2个方面考虑,须对研究区煤炭进行洗选处理。基于前期研究认识,浮选对于乌兰图嘎煤中As、Sb和W脱除效果相对较好,对于F和Hg的脱除效果较差,基于此,采用浮沉实验(重选法)以及XRD、XRF、SEM-EDS和EMPA等实验方法和测试手段,研究关键金属Ge以及Be、F、As、Hg等有害元素在不同密度级煤中的分布特征,结果表明:(1) 乌兰图嘎煤中矿物主要包括石膏、石英、黄铁矿、高岭石等,矿物含量随煤密度级增大而增加,电子探针分析结果表明,Co、As、Sb和Hg赋存在黄铁矿中。(2) 经过重选,低密度精煤中Ge元素富集,表明Ge主要以有机态存在,Be、F、As等可能与有机质相关,或者赋存在嵌布于有机质中的微细粒矿物中,煤中Hg和大部分亲石性元素在高密度级煤中含量较高,表明其赋存在矿物中。(3) 重选对于Hg元素的脱除效果较好,对Be、F、As和一些亲硫或亲铁性元素浮选脱除效果优于重选。建议乌兰图嘎低阶煤使用重选?浮选联合脱除法进行有害元素的脱除。      

贵州燃煤型砷中毒地区煤的微量元素的赋存状态

利用低温灰化（LTA）、X衍射粉晶分析（XRD）、扫描电子显微镜（SEM-EDX）、连续浸取实验等方法研究了贵州燃煤型砷中毒地区煤中微量元素的地球化学特征和赋存状态。结果发现：不同元素在高砷煤中的赋存状态不同;同一元素在高砷煤中的存在形式多种多样,可同时以可交换离子、碳酸盐结合态、硅酸盐结合态、硫化物和有机质结合态中几种形式存在;元素的赋存状态与元素的自身性质如元素（或离子）半径、电负性等和成煤作用密切相关。     

淮北煤田煤中常量金属元素特征及其对煤成烃的影响

煤中常量金属元素是煤的重要组成,也是影响煤物理化学性质及加工利用的主要因素。通过测试淮北煤田16个煤样的4种常量金属元素（Fe、Ca、K和Ti）含量,分析其含量和赋存特征,并在此基础上,对去除铁元素的煤样和原煤样进行了热模拟实验。实验结果表明,4种元素含量的变异系数较大,元素来源具有多样性;钾元素主要以无机状态存在,其他元素以无机和有机结合态存在;去除铁元素的煤样热解烃含量的降低幅度较大。      

兖州矿区煤中某些微量元素的赋存状态研究

微量元素的赋存状态决定其在煤的加工利用过程中释放的难易程度和毒性，弄清其在煤中的赋存状态，对准确评价元素的工艺性能、环境影响、作为副产品的可能性以及在地质意义上都是十分重要的。分析了微量元素在煤中的有机亲合性，采用数理统计方法，求得了微量元素与煤中有机显微组分、三态硫、灰分之间的相关性，并在浮沉实验的基础上，分析了微量元素的存在状态，通过研究向知，Ge、Ga、U、V、Cu、Th、Pb和Zn主要以无机态存在于煤中，F和Cl可能以有机态存在为主，As无机态和有机态存在的机率相似。     

淮南煤田深部A组煤中有害微量元素地球化学特征

以淮南煤田深部A 组煤为研究对象,全层刻槽采集了煤、夹矸和顶底板岩石样品,采用电感耦合等离子质谱仪 （ICP-MS） 测试分析了样品中13 种有害微量元素的含量,对比研究了其分布特征,结合Tessier 五步形态提取法和相关性分 析探讨了煤中有害微量元素的赋存形态。结果表明：（1） 与中国上陆壳中各种微量元素含量均值相比,淮南深部A 组煤中 B,As,Se,Mo,Cd,Pb,Hg 的富集系数均大于1,在A 组煤中表现为富集;A 组煤中B,As,Se,Cd 的含量均高于淮南煤 田上部B 组煤、华北煤以及中国煤中的含量均值;（2） 相关性分析和逐级提取实验结果表明,A 组煤中微量元素主要以残 渣态和铁锰氧化物结合态存在,两者质量分数之和达到55%~98%,其中Ni,Mo,Cd,Hg,Cu,Pb 和Zn 主要赋存于硫化物 矿物中,Mn 主要赋存于碳酸盐矿物中,V,Cr,Se,B 和As 主要赋存于硅铝酸盐等黏土矿物中。（3） B 元素示踪物源及沉 积环境结果显示,淮南煤田深部A 组煤成煤环境为海相咸水沉积环境,稳定的咸水沉积环境以及受海水影响等因素导致A 组煤中微量元素出现不同程度的富集。     

煤中有害微量元素的赋存状态

基于前人资料的分析总结，系统探讨了煤中Ag等26种有害微量元素的赋存状态。研究结果表明：煤中有害元素或多或少都与无机质、有机质有联系，只是联系程度不同。有些在地壳中被认为彼此关系不大的元素，在煤中却密切相关。煤中B、Be、Br等主要以有机相赋存，其它有害元素主要与矿物质有关。     

Geochemistry and Modes of Occurrence of Hazardous Trace Elements in the No. 11 Coal Seam, Antaibao Surface Mine, Shanxi Province

Concentrations of seventeen hazardous trace elements including As, Pb, Hg, Se, Cd, Cr, Co, Mo, Mn, Ni, U, V, Th, Be, Sb, Br and Zn in the No.ll coal seam, Antaibao surface mine, Shanxi Province were determined using Instrumental Neutron Activation Analysis （INAA）, Inductively Coupled Plasma Atomic Emission Spectrometry （ICP-AES）, Cold-Vapor Atomic Absorption Spectrometry （CV-AAS） and Graphite Furnace Atomic Absorption Spectrometry （GF-AAS）. Comparisons with average concentrations of trace elements in Chinese coal show that the concentrations of Hg and Cd in the No. 11 coal seam, Antaibao surface mine are much higher. They may be harmful to the environment in the process of utilization. The variations of the trace elements contents and pyritic suffur in vertical section indicated that： （a） the concentrations of As, Pb, Mn, and pyritic sulfur decrease from roof to floor; （b） the concentrations of Cr, Zn and Mo are higher in roof, floor and lower in coal seam; （c） the concentration of Br, Sb, and Hg are higher in coal seam and lower in roof and floor; （d） the concentrations of Mo, V, Th and AI vary consistently with the ash yield. Cluster analysis of trace elements, pyritic sulfur, ash yield and major elements, such as AI, Fe, P, Ca shows that： （a） pyritic sulfur, Fe, As, Mn, Ni, Be are closely associated and reflect the influence of pyrite; （b） Mo, Se, Pb, Cr, Th, Co, Ca and A! are related to clay mineral, which is the main source of ash; （c） U, Zn, V, Na, P maybe controlled by phosphate or halite; （d） Hg, Br, Sb and Cd may be mainly organic-associated elements which fall outside the three main groups. The concentration distribution characteristics of trace elements in coal seam and the cluster analysis of major and trace elements showed that the contents of trace elements in the No. 11 coal seam, Antaibao surface mine, are mainly controlled by detrital input and migration from roof and floor.     

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.     

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.     

Geochemical characteristics of the coal gangues from the Du’erping coal mine,Xishan coalfield,North China

Inductively coupled plasma mass spectrometry, inductively coupled plasma optical emission spectroscopy, hydride generation-atomic fluorescence spectrometry, emission spectrometry, X fluorescence spectrometry, and X-ray diffraction were employed to study the geochemistry and mineralogy of coal gangues from Nos. 2, 3, and 8 coal seams of the Du’erping coal mine, Xishan coalfield, Taiyuan, Shanxi Province. The study revealed that compared with the sedimentary cover, upper continent crust, Carboniferous-Permian coal from North China, as well as most coal in China, coal gangues from Nos. 2 and 3 coal seams are rich in Li, Be, Sc, Cr, Cu, Ga, Ba, Th, Nb, Cd, Pb, Ta and rare-earth elements, and coal gangues from No. 8 coal seam are rich in Li, Sc, V, Cr, Ga, U, and rare-earth elements. Compared with the Carboniferous-Permian coal from North China and most coal in China, coal gangues from Nos. 2, 3 and 8 seams are rich in Rb, V, Cs and Sr. Therefore, The Du’erping coal gangues in the Xishan coalfield are rich in most hazardous trace elements and rare-earth elements, wherein the contents of Ga and Li reach the industrial grade and have significance for industrial utilization. On the whole, coal gangues of the Shanxi Formation from the Permian are rich in more trace elements than those of the Carboniferous Taiyuan Formation. The distributions of REE show obviously dipping rightwards with negative Eu anomalies. The contents of rare-earth elements in the three seams are quite different. All of the above indicate that the source of the rare-earth elements is terrigenous debris. Minerals in No. 2 seam identified by X-ray diffraction mainly include quartz, kaolinite, in addition to calcite, pyrite, apatite, epidote, and epsomite. No. 3 seam mainly contains quartz, kaolinite, in addition to a small amount of sodium feldspar, calcium nitrate, iron ore, gypsum, and vivianite. No. 8 seam mainly contains kaolinite, dickite, quartz, illite, and a small amount of hematite and U. The correlations between major elements and trace elements in coal gangues of the Du’erping coal mine analyzed by using SPSS (Statistical Product and Service Solutions) indicate that the trace alkali elements and rare-earth elements occur mainly in such clay minerals as kaolinite.     

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.     

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.     

河北开滦矿区煤洗选过程中 15种主要有害微量元素的迁移和分配特征

以河北开滦矿区晚古生代煤及其洗选产品为例,运用电感耦合等离子体质谱 (ICP-MS)和冷原子吸收光谱 (CV-AAS)方法对煤中主要微量有害元素 (包括 Be、 Cr、 Co、 Ni、 Cu、 Zn、 Ga、 As、 Se、 Mo、 Tl、 Pb、 Th、 U和 Hg)的含量及其在洗选过程中的迁移和分配特征进行了研究.通过对开滦矿区 10个矿井 47个煤层刻槽样品主要有害微量元素含量的统计,发现开滦矿区晚古生代煤中 Cr、 Ni、 Cu、 Zn、 Pb和 As富集.通过对原煤精煤中煤尾煤煤泥两套系列样品的分析,发现主要有害微量元素在精煤中都有不同程度的脱除,中煤中相对富集的元素有 Se和 Th,明显被脱除的元素有 Co和 Tl.除 Tl以外,尾煤中主要微量有害元素均有不同程度的富集,以 As的富集率最高,可达 34.4%, Hg的富集率最低,为 1.1%.煤泥中所有微量有害元素均相对富集,以 Hg的相对富集率最高,达 78.4%.因此,如果对尾煤和煤泥加以利用,需要特别关注 As和 Hg等微量有害元素对环境的影响.主要微量有害元素在洗选过程中的分配行为主要受控于它在煤中的赋存状态.     

Mineralogical and elemental variation of coal from Alberta, Canada: an example from the No. 2 seam, Genesee Mine

Mineralogy and elemental contents were determined on 18 samples from a vertical profile of the No. 2 seam, Genesee mine, AB. The samples analyzed consist of coal, coaly shale, shaly coal, carbonaceous shale, shale, mudstone and siltstone. Proximate analysis was determined on all samples. Elemental analyses were determined by instrumental neutron activation analysis (INAA) for all elements except As, B, Cd, Hg, Mo, Pb, Se (Atomic Absorption) and B, Ba, Be, Co, Cr, Cu, Li, Mn, Nb, Sr and V (inductively coupled plasma-emission spectroscopy, ICP-ES). Samples were low temperature ashed (LTA), X-ray diffraction (XRD) and X-ray fluorescence (XRF) were used to determine quantitative major mineralogy. Accessory mineralogy was determined with Scannining Electron microscope/energy dispersive X-ray analyzer (SEM/EDX) on four samples. In general, the coals in the Genesee mine are within the low end of the range for trace element contents given by Swaine [Swaine, D.J., 1990. Trace Elements in Coal. Butterworths, London, 278 pp.] for most coals. High contents of Cr (9–2620 ppm) and Ni (1–1440 ppm) can be related to an increased amount of a Cr–Ni–Fe oxide (chromite–magnetite?) likely derived from ultrabasic diatremes in the Golden-Columbia Icefields, BC area. The No. 2 seam of the Genesee mine can be divided into two geochemical cycles on the basis of mineralogy, trace element contents and rare earth element (REE) behavior. Cycle I consists of quartz, calcite and kaolinite, lower trace element contents, REE slightly enriched in high rare earth elements (HREE), and thick coal with few partings. Cycle II consists of quartz, calcite, kaolinite, illite, mixed layer and/or expandable lattice clays, feldspar, gypsum, calcium aluminum sulfate hydrate, clinoptilolite, calcite and diopside, higher trace element contents, REE slightly enriched in light rare earth elements (LREE) and thin coal with a greater frequency of partings. The differences between the two geochemical cycles can be accounted for by a decreasing stability of the peat-forming environment resulting from an increasing fluvial influence and volcanogenic input.     

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.