Geochemical and mineralogical anomalies of the late Permian coal in the Zhijin coalfield of southwest China and their volcanic origin

This paper describes the influence of volcanic ash on the concentrations and occurrences of associated elements in coal in the Zhijin Coalfield in western Guizhou Province, China. Our studies reveal that the No. 9 coal seam in the Zhijin Coalfield has very high content of Fe (4.34%), Cu (369.90 μg/g), U (49.6 μg/g), Mo (63.10 μg/g), Zn (33.97 μg/g), and Zr (841.80 μg/g). The studies have also found that elements, such as Fe and Cu, do not occur as sulfides in this coal seam, in sharp contrast to many other coal seams in China. The geochemical and mineralogical anomalies of the coal seam are attributed to synsedimentary volcanic ash. In addition to normal macerals and minerals in coal, a volcanic-influenced material (VIM) derived from volcanic ash, detrital material of terrigenous origin and organic matter was identified under polarized-light reflectance microscopy and scanning electron microscopy equipped with energy-dispersive X-ray (EDX) analyzer. The volcanic-influenced material is the main carrier of the above elements in this coal. Six types of the volcanic-influenced material (VIM-1, VIM-2, VIM-3, VIM-4, VIM-5, and VIM-6) are further distinguished on the basis of their structures and compositions. To the best of our knowledge, this is the first report that presents a detailed classification of coal components with a high content of volcanic ash.     

煤炭显微煤岩组分与工业分析关系研究

通过分析宁夏各煤田中部分具有代表性煤矿勘查阶段钻孔煤岩煤样测试数据,研究了煤的显微煤岩组分与工业分析之间的关系。随着煤中有机组分、无机组分含量的变化,煤的灰分、挥发分、固定碳发生变化。煤中有机组分含量大于90%时,煤中灰分与黏土类含量存在正相关,挥发分与惰质组和壳质组含量均存在正相关,且惰质组含量影响更大;有机组分含量小于90%时,煤中灰分与惰质组和黏土类含量均存在正相关,且惰质组含量影响更大,挥发分与壳质组含量存在正相关。煤中固定碳含量受镜质组含量影响最大,二者存在正相关。     

沁水煤田15号煤中氟的赋存状态及其沉积环境分析

氟是煤中有害元素之一,燃煤型氟排放造成的污染已经对人类的健康安全构成威胁。研究煤中氟赋存状态及其沉积环境,对掌握高氟煤分布规律及控制燃煤造成的氟排放具有重要意义。通过对沁水煤田内6座煤矿15号煤样品的分析发现:煤中氟含量与灰分显著相关,与黄铁矿硫、有机硫无相关关系,表明煤中氟主要以无机物形式赋存,且与含硫矿物无关;与钾、镁、硅、铝等元素含量具有显著的相关关系,表明氟有可能的主要赋存形式为金云母、氟金云母等矿物,以及以吸附存在于高岭石、勃姆石、伊蒙混层等黏土矿物中;与钙、磷元素含量无显著相关性,表明氟不以氟磷灰石、含氟羟基磷灰石等矿物大量赋存。此外,通过对沁水煤田15号煤的沉积环境分析发现,弱还原环境、较低盐度、偏酸性、较强的水动力条件有利于该区域煤中氟的富集。     

On the geochemistry of indium in coal-forming process

The content and distribution of In in 168 samples from 7 coal deposits in Bulgaria were studied, using a spectrochemical method with a detection limit of 0.002 ppm. Indium is present in all samples, its content varying from 0.002 to 0.167 ppm in the coal and from 0.005 to 0.57 ppm in the ash. The mean contents for individual deposits do not differ statistically, and for all the deposits the In concentration (ppm) can be expressed generally by the equation In = 0.00068 A (A is the coal ash content in %).Of the petrographic constituents of coal, vitrain, xylene and liptain are enriched in In. In is associated with both the organic and with the inorganic matter of the coal. Inorganic matter and clay minerals in particular, act only as carriers of Indium. In contrast, organic matter concentrates In only to a small degree relative to other trace elements.     

粉煤灰对污水处理的效果及其环境影响试验研究

循环流化床燃烧产生的粉煤灰按不同比例与污水充分混合,其对污水中P的去除率可达90%以上;对COD的去除率为45%左右;对NH3-N的去除效果较差,最高不超过11%。由于粉煤灰含有大量钙,可以与粉煤灰中的磷酸盐形成沉淀,故采用循环流化床产生的粉煤灰可以有效处理含P较高的污水。文章研究了粉煤灰中重金属在污染水中释放规律,如Pb、Cd、Cu、Cr及Ni等,由于粉煤灰与污水浸泡后pH值呈碱性,且污水中含有大量有机物质,使反应体系呈还原状态。因此,粉煤灰中的重金属可以稳定存在,粉煤灰在污水中几乎不释放重金属,所以未加任何处理的粉煤灰在浸泡过程中不会对环境产生重金属污染。为此,粉煤灰可用于井下采空区回填,也可用于路基填充等。由于粉煤灰中少量碱性物质溶于水中,可使地下水pH值升高。     

Geochemistry of high-temperature coal ashes and the sedimentary environment of the New South Wales coals, Australia

Chemical analyses of high-temperature coal ashes were used to establish the distribution, association and relationship between major inorganic elements such as Si, Al, Ti, Fe, Mn, Mg, Ca, Na, K, P, S and CO₂ in a number of New South Wales economic coal seams and to study the composition and character of mineral matter in these coals. The methods used for the evaluation of the data were statistical analysis (univariate and bivariate), ratios, normative mineral composition and variation diagrams.The distribution of major and minor inorganic elements in coal appears to be related to the amount of mineral matter occurring in coal (determined as ash yield) and its mineralogical composition. The quantitative variations in levels of these elements can be classified as in-seam and inter-seam variations. In-seam variations are largely ash yield dependent, i.e. the levels of an element (wt.%) in coal increase along with the increase of its ash content (wt.%). The inter-seam variations are more complex and are related to both ash yield and to the mineralogical composition of mineral matter.The principal components of New South Wales coal ashes are silicon and aluminium. Silicon may be present as silica or combined with aluminium in different proportions to form clay minerals, such as kaolinite, illite, mixed-layer clay minerals, and smectite. Thus, the concentration levels of aluminium in relation to silicon in coal may give an indication about the character of clay minerals present in coal.Ratios and correlation coefficients of element pairs such as Al and Ti, Na and K, and Na and Al were used to determine differences in the chemical composition of high-temperature coal ashes of seams from various stratigraphic positions and provinces. In some seams the nature of associations of these elements is more significant than in others. This is interpreted as being a product of specific environmental conditions controlling the deposition of these seams.The nature of clay mineral content in coal is believed to be a major reason for chemical dissimilarities found between seams of various stratigraphic levels and geographic areas. For example, in some seams kaolinite, in others expandable clay minerals are dominant. The vertical distribution of these minerals has a stratigraphic significance. Within the Upper Permian Newcastle Coal Measures a trend from kaolinite-rich through to expandable minerals-rich and to kaolinite-rich assemblages can be observed from the bottom to the top. These changes are noticeably gradual.All significant variations in the clay mineral assemblages could relate to the long-term changes in the provenance of sedimentary material, weathering conditions in the source area and the rate of subsidence in the place of deposition. These changes are associated with major tectonic events controlling the history of sedimentation within the paralic Sydney and Gunnedah Basins during the Permian.     

The role of sulphide and carbonate minerals in the concentration of chalcophile elements in the bituminous coal seams of a paralic series (Upper Carboniferous) in the Upper Silesian Coal Basin (USCB), Poland

Sulphide and carbonate minerals from nine bituminous coal seams of a Paralic Series were investigated by means of polished-section microscopy, scanning electron microscopy and absorption spectral analyses. In addition to syngenetic accumulations of kaolinite, illite and quartz, diagenetic veinlets of subhedral pyrite and marcasite most often occur in vitrinite clast fissures and in post-tectonic fissures, nests and lenses with fusinite. Epigenetic anhedral and subhedral grains of ankerite, dolomite, siderite and calcite are also frequently found in post-tectonic veins. Pyrite replaced some of the marcasite grains and it dominates in older coal seams in the Flora Beds as compared with the Grodziec Beds. Occasionally there are anhedral and subhedral galena, sphalerite and chalcopyrite grains among coal macerals as well as cerussite among post-tectonic carbonate veins. They all represent the only minerals that are abundant in definite chalcophile elements (Cd, Co, Cu, Ni, Pb, Zn). In addition to the minerals just mentioned, the elements occurred in pyrite and ankerite grains, which contained inclusions of fusinite and other minerals (among others, clay and carbonate minerals in pyrite, pyrite in carbonates). Although there is a low content of minerals accumulating Cd, Co, Cu, Ni, Pb and Zn, the minerals significantly influence the average concentration of elements in the coal seams. In the Grodziec Beds, mineral matter, especially carbonates and sulphides, determines (>50%) the concentration of Cd, Cu, Pb and Zn in coal. The basic part of Cd, Co and Ni in the coal seams of the Grodziec Beds and of Co, Cu, Ni, Pb and Zn in coal seams of the Flora Beds originates from organic matter. These regularities can be important, from an ecological perspective, in stating whether the coals investigated are useful for combustion and in chemical processing.     

王洼煤矿扩大延伸勘探区煤质特征

通过对王洼煤矿扩大延伸勘探区可采煤层煤的煤岩特征、物理化学性质和工艺性能的分析研究,阐述了该区可采煤层煤的煤质特征及其变化规律：该区各可采煤层煤的显微有机组分中镜质组含量大于惰质组,二者约占89％,壳质组占1％左右,煤的无机组分占10％左右,并以粘土矿物为主。水分含量在8％左右,该区自西向东煤的灰分产率、挥发分产率、硫分、水分逐渐降低,属特低灰-低灰、低-中硫、特低磷-低磷,中高-高挥发分,高热值、不具粘结性的长焰煤、不粘煤。     

宁夏鸳鸯湖矿区煤的可选性特征

鸳鸯湖矿区以不粘煤为主,长焰煤次之,是良好的煤化工和动力用煤。从煤岩特征,煤的筛分、浮沉、煤及矸石的泥化程度试验等方面,对矿区及各井田煤的可选性特征进行了研究,研究表明：清水营井田煤中粘土类矿物较多,可选性较差,其它井田可选性相对较好;矿区煤中粘土矿物多呈细胞充填状,惰质组含量较高,难选出灰分很低的煤;当浮煤灰分控制在6．00％～11．00％,浮煤产率大于80％,煤为中等可选-易选;煤遇水易泥化,矸石为高泥化程度。研究结果可为煤的洗选工艺设计提供依据。     

Mineral matter in coals and their reactions during coking

Degradation of coke in the blast furnace is influenced by its inherent mineral matter, the formation of which is itself dependent upon the nature of the coal mineral matter. To date few studies have been made of coke mineralogy and its relationship to the mineralogy of the parent coal. In this study the effect of carbonisation on coal mineral matter has been investigated by a detailed quantitative mineralogical examination of nine cokes and their parent coals. The quantitative analysis was performed on X-ray diffraction patterns of the mineral matter of cokes and coals, using SIROQUANT^™. Coke mineralogy and its composition varied strongly between cokes, more strongly than variations in elemental composition of the ash. The mineral matter in the studied cokes consisted of crystalline mineral phases and also significant levels of amorphous phase (ranging between 44 and 75%). Decomposition of clays such as kaolinite, montmorillonite, illite and chamosite produced the amorphous phase and some of the crystalline mineral phases such as mullite, γ-alumina, spinel, cristobalite and leucite. The type of association of mineral matter in coals had an important role in how the clays decomposed. For example, association of kaolinite with silica-bearing minerals in intimate intermixture favoured formation of mullite over γ-alumina. Akermanite and diopside result from reaction of kaolinite with associated calcium bearing minerals (calcite, dolomite or ankerite). Quartz, fluorapatite and the three polymorphs of TiO₂ (anatase, brookite and rutile) were the coal minerals that were least affected during carbonisation, as they were also found in the cokes, yet even they were affected in some cases.     

High chromium contents in Tertiary coal deposits of northwestern Washington — A key to their depositional history

Chromium contents obtained from 20 coal and 5 associated rock samples collected from the basal part of the Eocene Chuckanut Formation, in Skagit and Whatcom counties, northwest Washington, range between 30 and 300 ppm (mean 120 ppm whole-coal basis). The lenticular coals, ranging in rank from subbituminous to anthracite, and with an ash content of 12–46%, crop out along the western flank of the Cascade Range. Results of X-ray diffraction analysis of low-temperature ash show that the mineral matter in the coal samples consists predominantly of quartz and clay (kaolinite, illite and chlorite group). However, accessory minerals, isolated from the coal samples and analyzed by X-ray diffraction, scanning electron microscope and optical methods, contain angular fragments and euhedral crystals of the spinel group (chromite, magnetite and trevorite ), kaolinite-serpentine group (antigorite and chrysotile), chlorite group, amphibole group and pyroxene group minerals (augite, diopside and enstatite), all of which are commonly enriched in chromium.Although associated primarily with the inorganic fraction of the coal, concentrations of chromium in the samples show no statistically significant correlation with ash content. Localized concentrations of chromium in the coal are the result of natural contamination from the alteration of detrital chromium-bearing mineral grains introduced into the peat-forming mires from nearby Jurassic ophiolite bodies. The coals formed in the early Eocene, in rapidly subsiding small basins that developed during the uplift and erosion of the pre-Tertiary ophiolite terrain. Scattered bodies of source rock, random distribution of chromium-bearing minerals within the coal and sample heterogeneity account for the variation in Cr contents of the samples.     

Characteristics of Coal Ashes in Yanzhou Mining District and Distribution of Trace Elements in Them

In the process of combustion of coal organic and inorganic materials in it will undergo a complex variation.Part of thew will become volatiles and,together with coal smoke,enter into atmosphere,some will remain in micro-particulates such as ash and dust and find their way into atmosphere in the form of solid particles,and the rest will be retained in ash and slag.Coal ashes are the residues of organic and inorganic substances in coal left after coal combustion and the compostition of coal ashes in dependent on that of minerals and organic matter in coal.This paper deals with the chemical composition of coal ashes,the distribution of trace elements in them and their petrological characteristics,and also studies the relationship between the yield of coal ashes and the distribution of trace elements.In addition,a preliminary study in also undertaken on the factors that affect the chemical composition of coal ashes.As viewed from the analyses of coal ash samples collected from the Yanzhou mining district,it can be seen clearly that coal ashes from the region studied are composed chiefly of crystalline materials,glassy materials and uncombusted organic matter and the major chemical compositions are SiO2,Al2O3,Fe2O3,and CaO,as well as minor amounts of SO3,PWO5,Na2O,K2O and TiO2.During the combustion of coal,its trace elements will be redistributed and most of them are enriched in coal ashes.At the same time,the concentrations of the trace elements in flying ash are much higher than those of bottom ash,i.e.,with decreasing particle-size of coal ashes their concentrations will become higher and higher.So the contents of trace elements are negatively proportional to the particle-size of coal ashes.There has been found a positive correlation between the trace elements Th.V.Zn,Cu and Pb and the yield of coal ashes while a negative correlation between Cl and the yield of coal ashes.     

内蒙古胜利煤田共生锗矿的成因地球化学初探

用统计和作图的分析方法,对内蒙古胜利煤田中共生锗矿床的锗品位与挥发分、灰分、硫分的关系进行了研究。结果表明煤中锗品位与挥发分呈正相关、与原煤灰分负相关、与洗煤灰分正相关关系;全区煤属中硫煤,锗品位与原煤和洗煤硫分均呈正相关关系,煤的灰分指数较低(3 579);锗分布不均匀,富锗煤矿明显属于断裂坳陷边缘沉积,锗品位可以在煤层的顶部、中部、底部同时或单个部位呈现高值,大多数煤层中部出现锗高品位值,这有别于以往所报道的锗品位只在煤层顶、底部相对富集的研究结论。认为胜利煤田锗主要与有机质结合;锗的有利聚集条件是水动力较弱、地下水位较低、强还原的停滞沼泽环境;泥炭聚集阶段有机质的吸附作用是锗的主要富集机制。     

Speciation of Cu in MSWI bottom ash and its relation to Cu leaching

In Flanders, recycling of bottom ash is mainly inhibited by the high leaching of Cu. Although it has been proved that dissolved organic C plays a major role in the Cu leaching, the possible role of inorganic Cu mineral speciation has never been experimentally examined. In this study the speciation of Cu is investigated using a combination of optical microscopy and electron microprobe –WDX/EDX. Several Cu species were determined. Metallic Cu (with or without an oxide shell), CuO and Cu₂O were the most abundant. These particles were most likely present in wire-like structures. Copper also occurred as alloy (brass, bronze, zamak), and was found frequently together with typical elements such as Ca, Cl and S. Finally, small metallic Cu particles seemed to be trapped in or precipitated on oxides and silicates. Based on this Cu speciation study, pure Cu minerals were selected and leached as a function of time. The solubility after equilibrium of all studied Cu minerals never exceeded 20 μg/L (which equals 10% of the total Cu leaching).The effect of heating (2 h at 400 °C) on the speciation of Cu was investigated using the same combination of techniques. Results show that metallic Cu seemed to be converted to Cu oxide (mostly CuO) and that the particles were more porous after heating. These conclusions were verified by XRD analysis of the heated pure Cu minerals. After heating, the Cu minerals were also leached as a function of time, to study the impact on Cu leaching. Results indicate that their leaching had slightly increased in comparison with the non-heated Cu minerals. However, the major decrease in Cu leaching in heated bottom ash, more than neutralizes this effect and thus can be attributed to the destruction of organic matter and not to the (small) change in Cu speciation.     

Petrological considerations for the demineralization of Rajmahal coals with <Emphasis Type="Italic">Pseudomonas mendocina</Emphasis> B6-1

The present study entails the results of the petrological coniderations for demineralization of Rajmahal Gondwana coals with Psudomonas mendocina B6-1. Inertinite group macerals are the dominant constituents of these coals, followed by vitrinite group, while liptinite occurs in low concentration. The amount of Mineral matter is moderately high. The concentration of major, minor and trace elements is high when compared with Clarke values. After the treatment of these coals with Pseudomonas mendocina strain B6-1, a significant reduction in the elemental content of oxygen, hydrogen and sulphur was observed. A gradual reduction of pyrite phase due to bioleaching was identified and its signatures were reflected in the XRD spectra and FTIR absorption bands. Over 5 % reduction in the ash content and decrease of major, minor and trace element to variable degrees were also noticed. Fe, As, and Ca positively correlate with the ash removal percentage indicating that the samples with high concentration of these elements were prone to demineralization with Pseudomonas mendocina strain B6-1 whereas Ni, Zn, Cr and Cu, negatively correlate with the ash removal percentage and shows that their enrichment impeded the process of demineralization. With increasing concentration of vitrinite the removal of major/minor/trace elements also increased which is attributed to the possible association of these elements with the mineral matter occurring as superficial mounting and superficial blanketing over the vitrinite macerals. This could facilitate the bacterial access to the elements to act upon and remove it to the variable extent. Some minerals occur intergrown with inertinites causing restricted bacterial action owing to the nonexposure of the mineral particles and less surface area available to the bacteria for bioleaching. Sulfur removal strongly relates with increase in inertinite content and decrease in liptinite content. This appears that sulfur associated with liptinites have shown difficult removal condition. The maximum removal of the trace elements like Cd, Cu, Co, Zn and Pb was observed from the ‘banded dull coal’ samples of the Rajmahal basin while maximum removal of major/minor elements like Fe, Ca and Mg was noticed from the ‘banded bright coal’ samples. However, maximum removal of Mn and As was also observed in the samples of ‘banded coal’.     

Leaching capabilities of iodine monochloride (ICl) and diethylenetriamine pentaacetic acid (DPTA) at different concentrations and pH for some major and trace metals from coal and coal fly ash

In the present study, coal from Chakwal (Pakistan) was leached with an aqueous solutions of iodine monochloride (ICl) and diethylenetriamine pentaacetic acid (DPTA) of different concentrations. The effect of stirring time, concentration and pH was studied on the leaching of different metals from coal. The physicochemical parameters indicated that the coal was of reasonably good quality. The results indicated that with increase in time duration, the extraction of metals increased. In most of the cases, metal concentration increased in the leachate with increasing the concentration of the leaching agents. DPTA was found to be the best leaching agent for most of the metals. Higher extraction of metals from coal fly ash indicated that coal organic matter has a pronounced effect on the leaching. Higher concentration of metals was extracted from virgin coal and coal fly ash at low pH (p?>?0.00) as compared to high pH. DPTA extracted metals in higher concentration from virgin coal and coal fly ash at low pH as compared to ICl. Based on the present study, the most leached metals were Fe, Cu, Mn and the least were Pb, Ni, Cd and Cr.     

Depositional conditions of the coal-bearing Hirka Formation beneath Late Miocene explosive volcanic products in NW central Anatolia,Turkey

This work focuses on the relationship between the coal deposition and explosive volcanism of the Miocene basin, NW central Anatolia, Turkey. The coal-bearing Hirka Formation was deposited over the Galatian Andesitic Complex and/or massive lagoonal environments during the Miocene. The investigated lignite is a high ash (from 32 to 58%) and sulphur (from 1.43 to 3.03%) lignite which is petrographically characterised by a high humunite content. The mineral matter of the studied lignite samples is made up of mainly clay minerals (illite-smectite and kaolinite), plagioclase and quartz in Bolu coal field, clay minerals (illite-smectite, smectite and illite), quartz, calcite, plagioclase and gypsum in Seben coal field, quartz, K-feldspar, plagioclase and clay minerals (kaolinite and illite) in K?br?sc?k, and dolomite, quartz, clinoptilolite, opal CT and gypsum in Çaml?dere coal field. The differences in these four types of lignite with specific mineralogical patterns may be due to the explosive volcanic events and depositional conditions which changed from one coal field to the others. There is a zonation from SW to SE in the studied area for zeolites such as Opal CT+smectite-clinoptilolite-analcime-K-feldspar. Carbonate minerals are commonly calcite in Seben and K?br?sc?k coal fields. In Bolu, coal samples are devoid of calcite and dolomite. These analyses show that there is an increase in the amount of Mg and a decrease in the amount of Na from the northwestern part to the southern part in the study area.     

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.     

Geochemistry and origin of elements in some UK coals

Twenty-four UK coals ranging in rank with 4.6%–37.6% volatile matter were analysed for 46 major and trace elements. The samples were obtained from the UK Coal Bank and are representative of the major UK coal fields. The major element distributions are interpreted in terms of the mineralogical variations—quartz and kaolinite are largely responsible for the Si and Al, carbonates for Ca and Mg and pyrite for Fe. Also exerting an influence in some samples are siderite, Al-phosphate minerals and illite. Based on statistical relationships with the major elements, Rb, Cr, Th, Ce, Zr, Y, Ga, La, Ta, Nb and V are thought to be mainly present in the clay minerals, and As, Mo, Sb, Tl, Se and Bi and Pb are probably present in pyrite. Strontium and Ba are concentrated in a restricted number of samples related to the phosphate minerals. Germanium is the only element for which a major organic association can be demonstrated. Elements with an indirect association with the organic matter are Na, Cl, and Br in porefluids and possibly Te. The ash content is controlled mainly by the detrital input and the trace elements related to the ash content are therefore those elements associated with the clay minerals. Variations with rank would appear to be mainly related to the moisture content (porefluids). The trace elements associated with the quartz and clay minerals are thought to be dominantly detrital in origin. The non-detrital elements, essentially those contained in pyrite, are thought to have been incorporated in the depositional environment from waters with enhanced salinities through seawater ingress, hence there are positive relationships between S and trace element concentrations.     

沁水盆地南部煤中矿物赋存特征及其对煤储层物性的影响

煤中矿物可以影响煤储层物性,进而影响煤层气的开发。运用光学显微镜和扫描电镜研究沁水盆地南部煤中矿物的种类、含量和赋存特征。基于煤储层的平衡水等温吸附实验和压汞实验,研究了沁南地区煤中矿物对煤储层吸附性能和孔渗性能的影响。结果表明,柿庄北区块3号和15号煤平均矿物含量分别为10.68%和12.81%,且15号煤硫化物含量较高。扫描电镜下可观察到充填煤储层胞腔孔、粒间孔隙和微裂隙的方解石、黄铁矿、高岭石和石英。孔隙度和渗透率以及兰氏体积和煤中大中孔比例均随灰分产率的增加而减小,表明煤中矿物的存在会降低煤储层的吸附性能和孔渗性能,煤储层中矿物充填主要影响煤的大中孔和裂隙,影响煤层气在割理和裂隙中的渗流,导致孔隙度和渗透率下降,而少量粘土矿物充填微孔可导致煤的吸附性能下降。