Mineral matter and trace elements in coals of the Gunnedah Basin, New South Wales, Australia

The concentrations of major and trace inorganic elements in a succession of Permian coals from the Gunnedah Basin, New South Wales, have been determined by X-ray fluorescence techniques applied to both whole-coal and high-temperature ash samples. The results have been evaluated in the light of quantitative data on the minerals in the same coals, determined from X-ray diffraction study of whole-coal samples using a Rietveld-based interpretation program ( ™), to determine relationships of the trace elements in the coals to the mineral species present. Comparison of the chemical composition of the coal ash interpreted from the quantitative mineralogical study to the actual ash composition determined by XRF analysis shows a high degree of consistency, confirming the validity of the XRD interpretations for the Gunnedah Basin materials. Quartz, illite and other minerals of detrital origin dominate the coals in the upper part of the sequence, whereas authigenic kaolinite is abundant in coals from the lower part of the Permian succession. These minerals are all reduced in abundance, however, and pyrite is a dominant constituent, in coals formed under marine influence at several stratigraphic levels. Calcite and dolomite occur as cleat and fracture infillings, mostly in seams near the top and bottom of the sequence. The potassium-bearing minerals in the detrital fraction are associated with significant concentrations of rubidium, and the authigenic kaolinite with relatively high proportions of titanium. Zirconium is also abundant, with associated P and Hf, in the Gunnedah Basin coal seams. Relationships exhibited by Ti, Zr, Nd and Y are consistent with derivation of the original sediment admixed with the seams from an acid volcanic source. Pyrite in the coals is associated with high concentrations of arsenic and minor proportions of thallium; no other element commonly associated with sulphides in coals, however, appears to occur in significant proportions with the pyrite in the sample suite. Small concentrations of Cl present in the coal are inversely related to the pyrite content, and appear to represent ion-exchange components associated with the organic matter. Strontium and barium are strongly associated with the cleat-filling carbonate minerals. Ge and Ga appear to be related to each other and to the coal's organic matter. Cr and V are also related to each other, as are Ce, La, Nd and Pr, but none of these show any relationship to the organic matter or a particular mineral component.     

Mineral matter and the nature of pyrite in some high-sulfur tertiary coals of Meghalaya, northeast India

Coal samples collected from four different sources in the Jaintia Hills of Meghalaya, northeast India, have been investigated for their sulfur content, mineral matter, and to assess their potential behavior upon beneficiation. These coals contain high sulfur which occurs both in organic and inorganic forms. The organic sulfur content is much higher than the inorganic sulfur. Studies on different size and gravity fractions indicated that the mineral phases are concentrated in higher density fractions (d > 1.8) and in general are fine grained (<50 μm). Data of reflected-light optical microscope and electron probe micro-analysis (EPMA) revealed that minerals in these coals are sulfides-pyrite, marcasite, sphalerite, pentlandite; sulfates-barite, jarosite; oxides-hematite, rutile; hydroxides-gibbsite, goethite; phosphate-monazite; carbonate-calcite, siderite and silicates-quartz, mica, chlorite, and kaolinitic clay. The disulfides of iron occur in two modes — mainly pyrite and occasionally marcasite with wide size ranges and in various forms, such as: framboid, colloidal precipitate, colloform-banded, fine disseminations, discrete grains, dendritic (feathery), recrystallized, nuggets, discoidal, massive, cavity-fracture- and cleat-fillings. Framboidal pyrite has formed primarily due to biological activities of sulfur reducing bacteria in the early stages of coalification. Massive and other varieties have formed at later stages due to coalescence and recrystallization of the earlier formed pyrites. Sulfur isotopic values indicate a biogenic origin for the pyrites. Association of trace metals, such as Ni, and Zn has been recorded in these pyrites. Given the large fractions of organic sulfur present, these coals can be upgraded only partially to reduce the sulfur content by beneficiation.     

Mineral matter in coals: cleat minerals and their origin in some coals from the english midlands

In four coal seam profiles from the Cannock Coalfield, West Midlands, the cleat (joint) frequency is a function of lithotype (greatest in vitarin) and is inversely related to bed thickness. The cleat minerals were studied: (1) under the microscope (optical and electron); (2) by X-ray diffraction; and (3) chemically. The minerals present are pyrite, marcasite, sphalerite, galena (sulphides), quartz, kaolinite (silicates), ankerite, calcite (carbonates) and apatite. This sequence has features in common with diagenetic sequences recorded in other rock types and it is concluded that the cleat minerals in coal form in response to pore fluid evolution and movement during burial diagenesis. The elements are thought to originate from both the coal and the associated sediments, mainly mudrocks. Similarities in diagenetic sequences are in part a reflection of the importance of organic maturation reactions in all the rock types in the sequence, whereas differences are attributed to the dominance of these reactions in the coal itself.     

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.     

低熟煤中的孢粉与常量元素和微量元素的相关性初探

运用电离耦合等离子体原子发射光谱(ICP-AES)和X射线荧光光谱分析(XRF),对新疆八道湾煤矿中侏罗统西山窑组煤中的孢粉角质层进行了分析,测定了煤中的常量和微量元素。并对煤中孢粉和共伴生元素进行了回归分析,探讨了微量和常量元素的煤岩学及孢粉学属性,在微量元素与孢粉的煤相学应用方面作了初步尝试。结果表明,成煤的蕨类植物孢子和裸子植物花粉与某些常量元素和微量元素有着很高的相关性;蕨类植物孢子和裸子植物花粉的相对含量在煤中具有互补性,决定了它们与微量元素的关系也具有一定的互补性。     

Petrology of tertiary and cretaceous coals of southern Alaska

Petrologic analysis of more than 400 coal samples from four general areas of southern Alaska show that the coals possess overall similar compositions. The areas sampled include the Nenana field, Susitna lowland (Beluga and Yentna fields), the Matanuska field, and the Alaska Peninsula (Chignik, Herendeen Bay, and Unga Island fields). The coals are all of Tertiary age ranging from Paleocene to Miocene except for those of the Chignik Formation (Chignik and Herendeen Bay fields) which are of Late Cretaceous age. The Tertiary coals are from the Healy Creek, Suntrana, and Lignite Creek Formations (Nenana field), Kenai Group -Tyonek and Beluga Formations (Beluga and Yentna fields), Chickaloon Formation (Matanuska field), and Bear Lake Formation (Unga Island field).The southern Alaska coals share broad compositional affinities with coals from other areas of the world including British Columbia and Australia. They are consistently high in vitrinitic or huminitic components, and have variable but typically low amounts of inertinitic and liptinitic components. The coals with relatively high liptinite contents, the hydrogen-rich components, may be well-suited for use in synthetic fuel generation. Variations in the maceral compositions generally reflect changes in the primary vegetation cover and in the environment of coal formation. However, post-depositional thermal effects have progressively more severely altered coal-maceral assemblages in the easternmost part of the Matanuska field, and also have more strongly influenced the compositions of bituminous coals of the Chignik Formation on the Alaska Peninsula.Petrology of the southern Alaska coals indicates that they formed predominantly in forest-moor backswamp (paludal) environments on valley flats or flood plains of nonmarine, continental-fluvial systems. They typically originated as tree-vegetation peats in the telmatic zone.     

贵州燃煤型地方性砷中毒地区煤的矿物组成

采用低温灰化（LTA）和X衍射粉晶分析（XRD）,结合带X光能谱的扫描电子显微镜（SEM—EDX）等方法研究了贵州燃煤型地方性砷中毒地区煤的矿物组成,计算了各矿物的相对含量,初步探讨了煤中主要的含砷矿物。      

低阶煤吸附孔结构特征及其对甲烷吸附性能影响

低阶煤甲烷吸附特性研究对瓦斯含量预测、瓦斯抽采及危害防治有着重要意义,为此,选取陕西6个典型矿井低阶煤样,进行低温氮吸附、低压二氧化碳吸附及甲烷等温吸附实验,获得低阶煤吸附孔结构特征。利用微孔填充及单分子层吸附理论定量表征甲烷吸附特征参数与吸附孔结构参数之间的关系,明确吸附孔中甲烷吸附机理。结果表明：吸附孔的比表面积主要由微孔提供,甲烷吸附能力主要受吸附孔孔容大小控制,微孔孔容对吸附孔总孔容的贡献率在74.71%～88.97%。甲烷极限吸附量与吸附孔平均孔径呈线性负相关,与吸附孔孔容、比表面积呈线性正相关,Langmuir压力常数随吸附孔平均孔径、孔容和比表面积的增加仅在小范围内波动,无明显线性相关。6个低阶煤样的分形特征明显,综合分形维数为2.573～2.720,平均值为2.647,说明低阶煤吸附孔非均质性强,甲烷极限吸附量随分形维数增加先增加后减小,整体呈上升趋势。基于微孔填充和单分子层吸附理论可以定量表征低阶煤吸附孔结构与甲烷吸附能力之间的关系,甲烷极限吸附量计算值与实验测试值相对误差较小,长焰煤相对误差为4.47%～6.65%,不黏煤为13.77%～16.02%。研究成果可为后...     

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.     

Generation and expulsion of oils from Permian coals of the Sydney Basin,Australia

Organic geochemical and petrological assessment of coals/coaly shales and fine grained sediments, coupled with organic geochemical analyses of oil samples, all from Permo–Triassic sections of the Southern Sydney Basin (Australia), have enabled identification of the source for the widely distributed oil shows and oil seeps in this region. The Permian coals have higher hydrogen indices, higher liptinite contents, and much higher total organic matter extract yields than the fine grained sediments. A variety of source specific parameters obtained from n-alkanes, regular isoprenoids, terpanes, steranes and diasteranes indicate that the oil shows and seeps were generated and expelled predominantly from higher plant derived organic matter deposited in oxic environments. The source and maturity related biomarkers and aromatic hydrocarbon distributions of the oils are similar to those of the coals. The oil-coal relationship also is demonstrated by similarities in the carbon isotopic composition of the total oils, coal extracts, and their individual n-alkanes. Extracts from the Permo–Triassic fine grained sediments, on the other hand, have organic geochemical signatures indicative of mixed terrestrial and prokaryotic organic matter deposited in suboxic environments, which are significantly different from both the oils and coal extracts. The molecular signatures indicating the presence of prokaryotic organic matter in some of the coal extracts and oils may be due to thin sections of possibly calcareous lithologies interbedded within the coal measures. The genetic relationship between the oils and coals provides new evidence for the generation and expulsion of oils from the Permian coals and raises the possibility for commercial oil accumulations in the Permian and Early Triassic sandstones, potentially in the deeper offshore part of the Sydney Basin.     

Distribution of sulphur in the tertiary coals of Meghalaya,India

The distribution pattern of the different forms of sulphur in the coal seams of Meghalaya has been worked out. In general, the total sulphur content is found to increase from the base to the top of a seam. There is also a general trend of upward increase of sulphur content in the seam-wise sequence, i.e. the upper seam is found to contain more sulphur than the seam lying below. Pyritic sulphur shows an upward increasing tendency both intraseam- and interseam-wise. Variation in organic sulphur shows an apparent parallelism with that of total sulphur. A gradual decrease in total sulphur content is also seen in the coals of Meghalaya from east to west within the basin of deposition. This regional lateral variation in sulphur content was due to the more marine nature of the peat-forming swamps of the Khasi and Jaintia Hills (eastern Meghalaya) as compared to that of the Garo Hills (western Maghalaya).     

Lower Cambrian helcionelloid macromolluscs from South Australia

Early Cambrian univalve molluscs are predominantly represented by microscopic forms (body length of 1–3 mm), preserved mainly as phosphatised internal moulds with limited definable features. Macromolluscs (≥ 5 mm) are generally rare, occur in low abundance and are poorly preserved, often lacking apical features and ornament which hinders taxonomic assessment. New and previously undescribed material from lower Cambrian Hawker Group carbonates of the Flinders Ranges in South Australia includes four new taxa, Minastirithella silivreni gen. et sp. nov., Galeacalvus coronarius gen. et sp. nov., Helcionella histosia sp. nov., and Ilsanella enallaxa sp. nov. Three-dimensional silicified shell material preserved with intact apices offers new insight into protoconch morphology, growth habit (isometric vs. allometric) and developmental mode. This material supports previous suggestions that some micromollusc taxa may in fact be early ontogenetic stages (juveniles) of larger macroscopic taxa; such that the millimetric size range of helcionelloids conforms to the dimensions of earliest apical portion in some macromolluscs documented herein. However, taphonomic limitations associated with phosphatisation show that the morphology (especially height vs. width) of the apex can greatly influence the probability of steinkern formation and preservation potential for both micro- and macro-scale helcionelloids. Artificial inflation in the appearance of millimetric helcionelloids with an optimal morphology for phosphatisation is thus directly linked to taphonomic biases in the fossil record.     

Anthracitization of coals in the South Wales coalfield

Investigations by the Institute of Geological Sciences on potential geothermal water sites in the coalfield of South Wales have been reported. They are of considerable interest and revive the controversy about the nature of the heat-source responsible for the anthracitization of some coals in this classic area. In the absence of exposed post-Carboniferous igneous rocks in the coalfield, general opinion has favoured heat generation by friction along faults or “disturbances”. We re-examine the evidence in the light of more recent geophysical and geochemical investigations which suggest the possibility of igneous intrusions at a depth of about 3.5 km or shallower. The likely age of such intrusions is also considered. High seismic velocity basement rocks rise to only 2.5 km beneath the surface of the Carboniferous in the northwestern anthracitized zone of the coalfield and we suggest that anthracitization in South Wales is not the result of depth of burial nor of frictional heat but of proximity to a magmatic heat source associated with crystalline rocks of the basement.     

Determination of rank and petrographic composition of Jurassic coals from eastern Surat Basin,Australia

Petrographic analysis and rank determination were carried out on coals from a Jurassic sequence in eastern Surat Basin, Australia. The coals consist mainly of exinite-rich clarite, with desmocollinite as dominant maceral of the vitrinite group. Petrographically there is no significant variation in the composition of the coals. A herbaceous swamp type, free from severe oxidation/ dehydration, appears to have been a dominant depositional environment during the peat accumulation.The coal rank ranges from sub-bituminous B to high-volatile bituminous C/B. Vitrinite reflectance/ depth profile shows a uniform increase in coalification with depth of burial.     

Organic matter and trace elements in Precambrian rocks from South Africa

Precambrian cherts from the Fig Tree and Onverwacht groups of South Africa contain unusually high concentrations of chromium and nickel. The organic carbon content of these cherts (0.02–1.58%) shows a considerable variation with a maximum abundance in the Onverwacht group. Atomic H/C ratios (0.08–1.38) of the associated organic matter (kerogen) support the suggestion that the carbon isotopic values of kerogen have not been isotopically enriched by metamorphic processes. Chemically bound alipathic structures amount to about 10% by weight of the organic carbon content of a chert from the lowermost Theespruit succession.     

Palaeomagnetic results from Mounts Gambier and Schank,South Australia

Palaeomagnetic results are presented for two young volcanoes in southeastern Australia. Directions for the basalt and lava spatter, erupted near the beginning and end of activity at Mt Gambier respectively, are identical and suggest there was no long break in activity. The direction for basalt at Mt Schank differs from that of Mt Gambier by several degrees, and indicates that the two volcanoes differ in age, probably by three centuries or more. Directions for both volcanoes are much shallower than the present‐day geomagnetic direction at the locality. Palaeomagnetic field strength estimates, from baked ash at Mt Gambier and baked sand at Mt Schank, are higher than the present‐day field strength. Comparisons with other late Pleistocene and Holocene results suggest that ages for Mts Gambier and Schank are either greater than 7000 years or between 5000 and 1000 years. These conclusions are consistent with published radiocarbon ages from charcoal in fossil soil horizons sealed beneath ash deposits.     

Hydrocarbon—Generating Characteristics of Barkinite—Rich Colas from Late Permian Longtan Formation ,South China

Leping coal (including barkinite-rich coal) is a unique kind of coal,which is widely distrbuted in the Late Permian Longan Formation,South China,In this paper,ROck-Eval,Py-GC and simulation experiment via an open-system were used to study the hydrocarbon-generating potential,hydrocarbon composition.and hydrocarbon-generating model of barkiniterich coals from the shuicheng coal field of Guizhou Province,Southwest China.The results show that barkinite-rich coals have high hydrocarbon-generating potential,with S1 S2 being 211-311mg/g,and can produce large amounts of hydrocorbon at the high-maturity stage,mostly within the temperature range of 420-450℃(corresponding to VR0 1.1-1.5%);barkinite-rich coal is one of the better oil sources and light hydrocarbon and wet gas are the major hydrocarbon components,which account for 45% and 33% of the total hydrocarbons.respectively.These characteristics are of importance for exploring oil and gas resources in the Late permian Longtan Formation coals,southwest China.     

Heritage stone in South Australia

South Australia has the greatest utilisation of heritage or building stone in Australia because of its lack of timber resources. Consequently, natural stone was intensively used from the beginning of European colonisation. Building stones in South Australia, notable for their variety given the State’s diverse geology, can be challenging to designate as to their international importance. However, dimension stone in South Australia can also be designated as having national, regional, local or prospective importance. Commonly, stone in South Australia is restricted in use to a specific town, or even a single construction, and has only local significance except where use involves special stone characteristics, unusual stone masonry or use in a building with significant heritage. For instance, the town of Second Valley has a localised use of marble, likely the earliest use (1849) of this rock type in the State. Another example, ‘Adelaide Black Granite’, quarried since 1958, should probably be recognised internationally as a ‘Global Heritage Stone Resource’, as it has had intensive monumental use around Australia, utilisation as cladding in modern buildings, as well as paving and walling in Australia’s National Parliament in Canberra. It has also been exported, notably used for the Australian Embassy in Japan and for a major War Memorial at Le Hamel, France. South Australian slate quarries also provide significant heritage stone. For example, the Willunga Slate quarry south of Adelaide has been sourced for roofing slate and walling since 1840 and is arguably the longest continuous mining operation in Australia; this resource has obvious national significance given a period of quarrying extending to the present, coupled with national distribution of its products. Probably the most widespread stone sourced in South Australia is the surface limestone or calcrete, quarried in the Adelaide area until the 1850s and used for general construction. The stone continues to be used in rural areas. While arguably only of local significance, it could be considered to have national importance because of its extensive use in churches, public building, hotels, houses and simple walling across a vast area of South Australia. Additional research is needed to clarify the heritage status of many building stones used in South Australia.