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Colin R. Ward - One of the best experts on this subject based on the ideXlab platform.

  • Determination of mineral matter and elemental composition of Individual Macerals in coals from Highveld mines
    Journal of the Southern African Institute of Mining and Metallurgy, 2016
    Co-Authors: R.h. Matjie, Colin R. Ward, J.r. Bunt, Christien A. Strydom
    Abstract:

    are mined for South African chemical companies from six different collieries in the Highveld coalfield, located in the Mpumalanga Province of South Africa (Pinheiro et al., 1998–1999). Products containing coarse coal particles mixed with rock fragments (> 6 mm coal fraction) are transported from the mine sources to the preparation plant, where they are blended according to their availability to form a mixture that is suitable for the company’s coal conversion operations (Matjie et al., 2006; van Dyk et al., 2006). Finer coal particles are pulverized to 100% passing 75 m and combusted in boilers to produce energy or electricity for the domestic power and chemical industries (van Alphen, 2005).

  • High-resolution three-dimensional imaging of coal using microfocus X-ray computed tomography, with special reference to modes of mineral occurrence
    International Journal of Coal Geology, 2013
    Co-Authors: Alexandra N. Golab, Colin R. Ward, Asep Kurnia Permana, P. G. Lennox, Pieter Botha
    Abstract:

    Abstract Samples of coal from the Sydney and Bowen Basins of eastern Australia have been imaged at high resolution using a large-field, 3D microfocus X-ray computed tomography (μCT) system, with special but not exclusive attention to evaluating the modes of occurrence of the mineral matter within the coal. The samples imaged were 110 mm, 25 mm, 19 mm, 10 mm, and 4 mm in size, yielding voxel dimensions of 54, 30, 12, 6, and 3 μm respectively. Data collection was carried out using a helical stage, providing images with > 20002 voxels in the horizontal (X–Y) plane and up to 3500 voxels high. Three-dimensional image blocks derived from the scans were examined as cross-sections along orthogonal planes and as perspective images, manipulated to be viewed from any angle. Imaging after saturating the coal with X-ray attenuating brine was also carried out to highlight the distribution of connected micro-pores and cleats, and improve the detail of features seen within the samples. Features evaluated within the coals included the size and three-dimensional distribution of siderite nodules, and different types of mineral infillings in petrifactions of maceral components. Individual Macerals could also be identified within the coal, based partly on X-ray density and partly on the associated porosity and structure. In some cases high-resolution images enabled the nature of Individual plant particles to be identified within the coal samples. Mineral-filled cleats and open fractures were also evaluated, including the origin of radiating fracture patterns around siderite nodules in vitrinite. In some cases several generations of cleat and/or fractures could be distinguished, and the sequence of their formation and infilling was interpreted. Complementary analyses of the mineral matter in the samples were carried out using X-ray diffraction, as well as examination of polished sections by optical microscopy examination. Images obtained from the μCT scans were also registered against SEM–EDX and QemSCAN images of polished sections prepared from the same samples after scanning, providing a more definitive basis for identifying the different components and for integrating μCT data with results from other petrographic and electron microscope studies.

  • Occurrence of non-mineral inorganic elements in Macerals of low-rank coals
    International Journal of Coal Geology, 2010
    Co-Authors: Colin R. Ward, Lila W. Gurba
    Abstract:

    Abstract Electron microprobe study of Individual Macerals in low-rank coals of Permian to Tertiary age from Australia, New Zealand, Indonesia and Thailand has shown that measurable proportions of inorganic elements are consistently found in organic components, especially the vitrinite Macerals, in which no minerals or mineral inclusions are visible under the microscope. The vitrinites of such coals have been found to contain up to around 0.5% Al, 1.5% Ca, 0.1% Mg, 0.7% Fe and 0.2% Ti. The Al occurs without measurable proportions of Si, and hence does not represent sub-micron clay minerals within the maceral components. Inertinite Macerals in the coals, such as fusinite, typically contain lesser proportions of these elements, and often have no more than background ( Except where soluble minerals such as carbonates are also present, the proportion of Ca, Al and Fe indicated from microprobe analysis in the Macerals, especially in the vitrinites, is very close to the mobile proportion of the same elements indicated in previous studies from selective leaching techniques. This suggests that the elements occur as an inherent part of the organic structure in the Macerals, possibly as a combination of exchangeable ions, carboxylates, chelates and other organometallic compounds; they may also be held by physical absorption and adsorption mechanisms, or may possibly represent inorganic nanoparticles. The proportions of Al, Ca and Fe in the vitrinites of the samples studied decrease with coal rank. Although there are exceptions, these and other non-mineral inorganic elements (Mg, Ti) are also not usually detected by the microprobe in higher rank coals (above 75% carbon in vitrinite or around 0.6% vitrinite reflectance). Their absence is probably a consequence of expulsion from the maceral structures during the progressive aromatization associated with rank advance, by processes such as dehydration, decarboxylation and dehydroxylation.

  • Chemical functionalities of high and low sulfur Australian coals: A case study using micro attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectrometry
    Organic Geochemistry, 2010
    Co-Authors: Peter M. Fredericks, Colin R. Ward, Llewellyn Rintoul
    Abstract:

    The Macerals in bituminous coals with varying organic sulfur content from the Early Permian Greta Coal Measures at three locations (Southland Colliery, Drayton Colliery and the Cranky Corner Basin), in and around the Sydney Basin (Australia), have been studied using light-element electron microprobe (EMP) analysis and micro-ATR–FTIR. Electron microprobe analysis of Individual Macerals reveals that the vitrinite in both the Cranky Corner Basin and Drayton Colliery (Puxtrees seam) samples have similar carbon contents (ca. 78% C in telocollinite), suggesting that they are of equivalent rank. However, the Cranky Corner coals have anomalously low vitrinite reflectance (down to 0.45%) vs. the Drayton materials (ca. 0.7%). They also have very high organic S content (3–6.5%) and lower O content (ca. 10%) than the equivalent Macerals in the Drayton sample (0.7% S and 15.6% O). A study was carried out to investigate the impacts of the high organic S on the functional groups of the Macerals in these two otherwise iso-rank, stratigraphically-equivalent seams. An iso-rank low-S coal from the overlying Wittingham Coal Measures near Muswellbrook and coals of slightly higher rank from the Greta Coal Measures at Southland Colliery near Cessnock were also evaluated using the same techniques to extend the data set. Although the telocollinite in the Drayton and Cranky Corner coals have very similar carbon content (ca.78% C), the ATR–FTIR spectra of the vitrinite and inertinite Macerals in these respectively low S and high S coals show some distinct differences in IR absorbance from various aliphatic and aromatic functional groups. The differences in absorbance of the aliphatic stretching bands (2800–3000 cm−1) and the aromatic carbon (CC) peak at 1606 cm−1 are very obvious. Compared to that of the Drayton sample (0.7% S and 15% O), the telocollinite of the Cranky Corner coal (6% S and 10% O) clearly shows: (i) less absorbance from OH groups, represented by a broad region around 3553 cm−1, (ii) much stronger aliphatic C–H absorbance (stretching modes around 3000–2800 cm−1 and bending modes around 1442 cm−1) and (iii) less absorbance from aromatic carbon functional groups (peaking at 1606 cm−1). Evaluation of the iso-rank Drayton and Cranky Corner coals shows that: (i) the aliphatic C–H absorbances decrease with increasing oxygen content but increase with increasing organic S content and (ii) the aromatic H to aliphatic H ratio (Har/Hali) for the telocollinite increases with (organic) O%, but decreases progressively with increasing organic S. The high organic S content in the maceral appears to be accompanied by a greater proportion of aliphatic functional groups, possibly as a result of some of the O within maceral ring structures in the high S coal samples being replaced.

  • Comparison of elemental composition of Macerals determined by electron microprobe to whole-coal ultimate analysis data
    International Journal of Coal Geology, 2008
    Co-Authors: Colin R. Ward, Lila W. Gurba
    Abstract:

    The elemental composition of the Individual Macerals in a suite of Australian coals has been determined in polished sections using light-element electron microprobe techniques. The analyses of the Individual Macerals in each coal were combined with data on maceral abundance to produce an inferred chemical composition for the organic matter of the respective whole-coal samples, and this was compared, for each sample, to the respective whole-coal ultimate analysis data, corrected to a dry, ash-free (daf) basis. Except for slightly lower values in some lower-rank coals, the inferred percentages of whole-coal C estimated from the microprobe data were found to be very close to the respective whole-coal C percentages as determined by conventional ultimate analysis. The proportion of O in the coals indicated by the microprobe study, however, appears to be as much as 2% higher than that derived from the ultimate analysis data, especially in the lower-rank coal samples. The difference it may represent errors in calculating the O percentages in ultimate analysis, errors in the microprobe analysis due to difficulties in calibration or measurement, or increased proportions of O in the coals due to factors such as take-up with storage of the polished sections. The percentages of whole-coal N calculated from the microprobe data are up to 0.5% (absolute) below the proportion of N determined directly by whole-coal ultimate analysis. This may reflect the inherent difficulty of dealing with a light element at low concentrations by the microprobe technique, or it may indicate that some of the N occurs in the coals in mineral form. The percentages of whole-coal (organic) S calculated from the microprobe study are close to the percentages of organic S determined for each sample by more conventional techniques. With the exception of (organic) O, which may be affected by other factors, and also possibly of N, the electron microprobe technique appears from the study to provide results that are consistent with ultimate analysis over a wide rank range.

Lila W. Gurba - One of the best experts on this subject based on the ideXlab platform.

  • Occurrence of non-mineral inorganic elements in Macerals of low-rank coals
    International Journal of Coal Geology, 2010
    Co-Authors: Colin R. Ward, Lila W. Gurba
    Abstract:

    Abstract Electron microprobe study of Individual Macerals in low-rank coals of Permian to Tertiary age from Australia, New Zealand, Indonesia and Thailand has shown that measurable proportions of inorganic elements are consistently found in organic components, especially the vitrinite Macerals, in which no minerals or mineral inclusions are visible under the microscope. The vitrinites of such coals have been found to contain up to around 0.5% Al, 1.5% Ca, 0.1% Mg, 0.7% Fe and 0.2% Ti. The Al occurs without measurable proportions of Si, and hence does not represent sub-micron clay minerals within the maceral components. Inertinite Macerals in the coals, such as fusinite, typically contain lesser proportions of these elements, and often have no more than background ( Except where soluble minerals such as carbonates are also present, the proportion of Ca, Al and Fe indicated from microprobe analysis in the Macerals, especially in the vitrinites, is very close to the mobile proportion of the same elements indicated in previous studies from selective leaching techniques. This suggests that the elements occur as an inherent part of the organic structure in the Macerals, possibly as a combination of exchangeable ions, carboxylates, chelates and other organometallic compounds; they may also be held by physical absorption and adsorption mechanisms, or may possibly represent inorganic nanoparticles. The proportions of Al, Ca and Fe in the vitrinites of the samples studied decrease with coal rank. Although there are exceptions, these and other non-mineral inorganic elements (Mg, Ti) are also not usually detected by the microprobe in higher rank coals (above 75% carbon in vitrinite or around 0.6% vitrinite reflectance). Their absence is probably a consequence of expulsion from the maceral structures during the progressive aromatization associated with rank advance, by processes such as dehydration, decarboxylation and dehydroxylation.

  • Comparison of elemental composition of Macerals determined by electron microprobe to whole-coal ultimate analysis data
    International Journal of Coal Geology, 2008
    Co-Authors: Colin R. Ward, Lila W. Gurba
    Abstract:

    The elemental composition of the Individual Macerals in a suite of Australian coals has been determined in polished sections using light-element electron microprobe techniques. The analyses of the Individual Macerals in each coal were combined with data on maceral abundance to produce an inferred chemical composition for the organic matter of the respective whole-coal samples, and this was compared, for each sample, to the respective whole-coal ultimate analysis data, corrected to a dry, ash-free (daf) basis. Except for slightly lower values in some lower-rank coals, the inferred percentages of whole-coal C estimated from the microprobe data were found to be very close to the respective whole-coal C percentages as determined by conventional ultimate analysis. The proportion of O in the coals indicated by the microprobe study, however, appears to be as much as 2% higher than that derived from the ultimate analysis data, especially in the lower-rank coal samples. The difference it may represent errors in calculating the O percentages in ultimate analysis, errors in the microprobe analysis due to difficulties in calibration or measurement, or increased proportions of O in the coals due to factors such as take-up with storage of the polished sections. The percentages of whole-coal N calculated from the microprobe data are up to 0.5% (absolute) below the proportion of N determined directly by whole-coal ultimate analysis. This may reflect the inherent difficulty of dealing with a light element at low concentrations by the microprobe technique, or it may indicate that some of the N occurs in the coals in mineral form. The percentages of whole-coal (organic) S calculated from the microprobe study are close to the percentages of organic S determined for each sample by more conventional techniques. With the exception of (organic) O, which may be affected by other factors, and also possibly of N, the electron microprobe technique appears from the study to provide results that are consistent with ultimate analysis over a wide rank range.

  • variations in elemental composition of Macerals with vitrinite reflectance and organic sulphur in the greta coal measures new south wales australia
    International Journal of Coal Geology, 2007
    Co-Authors: Colin R. Ward, Zhongsheng Li, Lila W. Gurba
    Abstract:

    Abstract The elemental composition of the Individual Macerals in the Early Permian Greta Coal Measures of the northern Sydney Basin and adjoining Cranky Corner Basin, New South Wales, including some seams with high to very high organic sulphur contents, have been analysed in polished sections using light-element electron microprobe techniques, and the results evaluated in the light of vitrinite reflectance and other characteristics of the coals concerned. As with other Australian coals, the vitrinite Macerals in each sample have the lowest proportions of carbon and highest proportions of oxygen, and the inertodetrinite and fusinite Macerals the highest C and lowest O contents. Semifusinite and the liptinite Macerals have intermediate C and O percentages. Organic sulphur and organic nitrogen are also highest in the vitrinite Macerals of the Individual samples, and lowest in the fusinite and inertodetrinite components. The vitrinite Macerals in the Puxtrees seam of the Greta Coal Measures on the Muswellbrook Anticline, in the upper Hunter Valley, have similar elemental compositions (78% C) and similar reflectance values (Rv max around 0.7%) to vitrinites in the Late Permian bituminous coals in other parts of the Sydney-Bowen Basin. The vitrinites in the seams of the Cranky Corner Basin also have similar carbon contents to the Puxtrees seam material, suggesting a similar rank level, but have much lower vitrinite reflectance values (Rv max  = 0.4–0.5%), probably due to marine influence associated with the depositional system. The vitrinites in the Greta seam on the Lochinvar Anticline, in the Lower Hunter region, have higher carbon contents (83%) than the Puxtrees material, suggesting a higher rank level, but similar to lower vitrinite reflectance values (Rv max  = 0.6–0.7%). Vitrinite carbon is also constant through the seam profile, despite upwardly decreasing reflectance values in the seam due to progressive increases in marine influence. The vitrinites in the upper Greta seam and the Cranky Corner Basin coals have high to very high organic sulphur contents, again probably due to marine influence on the depositional process. The vitrinites in the Cranky Corner Basin coals, which have particularly high organic sulphur contents, also have somewhat lower oxygen contents in relation to their carbon percentages than those of other Australian seams, suggesting that the additional organic sulphur has replaced oxygen in the Macerals' molecular structure. The Macerals, especially the vitrinites, in the coals with high organic sulphur and anomalously low vitrinite reflectance also have up to 0.5% Al and 1% Ca intimately associated with the organic matter. Similar organically associated inorganic elements are commonly found in lower-rank (e.g. sub-bituminous) coals, but are usually lost from the organic matter at higher rank levels. The coals of the Greta Coal Measures therefore have vitrinite carbon contents consistent with a high volatile bituminous rank, but those seams or parts of seams with high organic sulphur due to substantial marine influence appear to have preserved the vitrinite reflectance values and organically associated inorganic elements more typical of lower-rank, sub-bituminous materials.

  • variations in coal maceral chemistry with rank advance in the german creek and moranbah coal measures of the bowen basin australia using electron microprobe techniques
    International Journal of Coal Geology, 2005
    Co-Authors: Colin R. Ward, Zhongsheng Li, Lila W. Gurba
    Abstract:

    Abstract Variations in the elemental composition of Individual Macerals in seams from the Permian German Creek and Moranbah Coal Measures in the Bowen Basin of Queensland have been studied over a wide range of coal ranks, using light-element electron microprobe techniques, to establish the coalification tracks of key Macerals in a single coal-bearing interval from subbituminous through bituminous coal to anthracite. Vitrinite reflectance (Rv max ) in the seams studied increases from 0.39% in the western part of the basin to over 3.5% in the east, apparently due to increases in burial depth. The study extends significantly the rank range covered by previous work on elemental analysis of Individual Macerals in the Gunnedah Basin, and provides a more useful basis than whole-coal analysis to evaluate the performance of coals in different utilisation processes. The microprobe results show that the carbon content of the telocollinite increases dramatically from 66% to 90% as the vitrinite reflectance of the coals (Rv max ) increases from 0.39% to around 1.75%, but increases only slightly, from 90% to 91%, as Rv max increases from 1.75% to 3.52%. Oxygen decreases from around 26% to approximately 5% as Rv max increases from 0.39% to around 1.75%, and then decreases only very slightly into the anthracite range. The nitrogen content of the telocollinite in these coals also appears to decrease slightly with rank advance, and appears moreover to display a relatively abrupt drop at around 2% Rv max . This may be associated with the development of ammonium illite in the mineral matter. Organic sulphur in the telocollinite, on the other hand, seems to remain essentially constant with rank advance, at least in this particular succession. In contrast to vitrinite, fusinite and inertodetrinite have significantly higher but somewhat more constant carbon contents, varying only from around 81% to 93% C over the rank range studied. Oxygen in these Macerals decreases from around 12% to a little over 2% with the same degree of rank advance. Sulphur and possibly nitrogen also appear to be significantly lower in fusinite and inertodetrinite than in the vitrinite of the same coal samples. Semifusinite is somewhat more variable in composition, with characteristics intermediate between those of the fusinite/inertodetrinite and those of the vitrinite in the same coal over the rank range studied.

  • Occurrence and distribution of organic sulphur in Macerals of Australian coals using electron microprobe techniques
    Organic Geochemistry, 1998
    Co-Authors: Colin R. Ward, Lila W. Gurba
    Abstract:

    The organic sulphur content of the Individual Macerals in Permian high volatile bituminous coals from the Gunnedah Basin of New South Wales, has been studied using an electron microprobe technique. Liptinite (chiefly sporinite) in the coal has the highest organic sulphur content and inertinite (mainly semifusinite) the lowest; the vitrinite Macerals have intermediate sulphur contents. These variations are responsible for the relatively low overall organic sulphur in inertinite-rich coals, typical of Australian Permian deposits. Neither marine influence on coal formation nor increases in coal rank appear to be associated with significant changes in organic sulphur of the Individual Macerals concerned.

Deyong Shao - One of the best experts on this subject based on the ideXlab platform.

  • pore types and pore network evolution in upper devonian lower mississippian woodford and mississippian barnett mudstones insights from laboratory thermal maturation and organic petrology
    International Journal of Coal Geology, 2017
    Co-Authors: Lucy T Ko, Robert G Loucks, Stephen C Ruppel, Paul C Hackley, Tongwei Zhang, Deyong Shao
    Abstract:

    Abstract Pore-evolution models from immature organic-matter (OM) -rich Barnett (0.42%R o ) and Woodford (0.49%R o ) mudstones were compared with models previously developed from low-maturity OM-lean Boquillas (Eagle Ford-equivalent) mudstones to investigate whether (1) different mineralogy (siliceous vs. calcareous) exerts different catalytic and sorption effects and influences OM-pore origin and evolution; and (2) different types of Macerals show different OM pore evolution history. Laboratory gold-tube pyrolysis, scanning electron microscopy (SEM) and thin-section petrography, organic petrography, and geochemical characterization were used to investigate the role of bulk mineralogy, maceral type, and thermal maturation on OM-pore evolution. Results suggest that mineralogy has little impact on OM-pore development and evolution. Macerals, identified using both SEM (platy OM, particulate OM, organic–mineral admixtures, Tasmanites ) and organic petrology (vitrinite, inertinite, amorphous organic matter [AOM]/bituminite, telalginite [ Leiosphaeridia , Tasmanites ]), do affect the origin and evolution of OM pores owing to differences in chemical compositions, generation kinetics, and activation-energy distributions between Tasmanites , matrix bituminite, and other types of Macerals. Leiosphaeridia and Tasmanites in Woodford mudstone samples exhibit a delay in onset and a shorter period of petroleum generation and pore development compared to the matrix bituminite in the Barnett and Woodford mudstone samples. Pre-oil solid bitumen was observed to have migrated into initial primary mineral pore networks at the bitumen generation stage in both Barnett and Woodford samples. At higher levels of thermal maturation, the volume of primary mineral pores decreases and the pore volume composed of modified mineral pores and OM pores becomes greater. Pore evolution and pore-type heterogeneity in these mudstones is a function of the initial mineral pore network, types of kerogen and Macerals, and generation kinetics of Individual Macerals upon thermal maturation.

  • pore types and pore network evolution in upper devonian lower mississippian woodford and mississippian barnett mudstones insights from laboratory thermal maturation and organic petrology
    International Journal of Coal Geology, 2017
    Co-Authors: Stephen C Ruppel, Robert G Loucks, Paul C Hackley, Tongwei Zhang, Deyong Shao
    Abstract:

    Abstract Pore-evolution models from immature organic-matter (OM) -rich Barnett (0.42%R o ) and Woodford (0.49%R o ) mudstones were compared with models previously developed from low-maturity OM-lean Boquillas (Eagle Ford-equivalent) mudstones to investigate whether (1) different mineralogy (siliceous vs. calcareous) exerts different catalytic and sorption effects and influences OM-pore origin and evolution; and (2) different types of Macerals show different OM pore evolution history. Laboratory gold-tube pyrolysis, scanning electron microscopy (SEM) and thin-section petrography, organic petrography, and geochemical characterization were used to investigate the role of bulk mineralogy, maceral type, and thermal maturation on OM-pore evolution. Results suggest that mineralogy has little impact on OM-pore development and evolution. Macerals, identified using both SEM (platy OM, particulate OM, organic–mineral admixtures, Tasmanites ) and organic petrology (vitrinite, inertinite, amorphous organic matter [AOM]/bituminite, telalginite [ Leiosphaeridia , Tasmanites ]), do affect the origin and evolution of OM pores owing to differences in chemical compositions, generation kinetics, and activation-energy distributions between Tasmanites , matrix bituminite, and other types of Macerals. Leiosphaeridia and Tasmanites in Woodford mudstone samples exhibit a delay in onset and a shorter period of petroleum generation and pore development compared to the matrix bituminite in the Barnett and Woodford mudstone samples. Pre-oil solid bitumen was observed to have migrated into initial primary mineral pore networks at the bitumen generation stage in both Barnett and Woodford samples. At higher levels of thermal maturation, the volume of primary mineral pores decreases and the pore volume composed of modified mineral pores and OM pores becomes greater. Pore evolution and pore-type heterogeneity in these mudstones is a function of the initial mineral pore network, types of kerogen and Macerals, and generation kinetics of Individual Macerals upon thermal maturation.

Maria Mastalerz - One of the best experts on this subject based on the ideXlab platform.

  • Petrographic characterization, variations in chemistry, and paleoenvironmental interpretation of Colombian coals
    International Journal of Coal Geology, 2020
    Co-Authors: Olga Patricia Gómez Rojas, Astrid Blandón, Carlos Perea, Maria Mastalerz
    Abstract:

    Abstract This study focuses on variations in petrographic composition and chemistry of Macerals from different coalfields in Colombia. The coal-bearing formations in Colombia occur in the age interval from the Maastrichtian in the Upper Cretaceous to the Paleogene and Neogene (Paleocene, Eocene, Oligocene, and Late Pliocene) up to Early Pleistocene. The coals range in rank from lignite to semianthracite. Petrographically, the coal is composed dominantly of Macerals of the vitrinite group (>50% by volume). The coals from the regions of Antioquia, Cordoba, and Caldas are characterized by relatively high proportions of liptinite (up to 30 vol%). The inertinite contents vary up to 30 vol%, and the coals from the regions of Boyaca and Guajira contain the highest quantities of this maceral group. The Colombian coals studied have low moisture, except for the coal from Caldas being lignite type A. The sulfur content ranges between 0.28 weigh % in coal from Guajira to slightly above 2% in coal from Cordoba and Cauca. The coal facies diagrams suggest that palaeomires developed mostly under limno-telmatic to wet forest mire conditions. The ratios of microlithotypes suggest that the original peat mires evolved under fluvial, upper deltaic and brackish settings. Overall coal petrography data suggest that peat-forming vegetation and water tables in palaeomires experienced significant variations between the Upper Maastrichtian to Pliocene - Early Pleistocene period. Variations in chemistry of coal Macerals reflect to large extent the coal rank variations. Specifically, with the increase in vitrinite reflectance (Ro), the contents of aliphatic functional groups decrease whereas those of the aromatic groups increase. The values of CH2/CH3 ratios also decrease with increasing coal rank (2.24 in Boyaca and 0.97 in Cauca). Expectedly, spectral differences between Individual Macerals are most distinct in the low rank coals (0.48% Ro).

  • Applications of micro-FTIR technique in studying hydrophobicity of coal
    International Journal of Coal Geology, 2017
    Co-Authors: J. Liu, Maria E. Holuszko, Maria Mastalerz
    Abstract:

    Abstract This paper investigates the application of micro-FTIR technique in predicting hydrophobicity of coal inferred from contact angle measurements. Two ranks of coal were selected: Pennsylvanian high-volatile bituminous coal from the Illinois Basin, USA (R o 0.59–0.63%) and Cretaceous medium-volatile bituminous coal from British Columbia, Canada (R o 1.19–1.50%). Sessile drop and captive bubble techniques were used to measure contact angle on coal surfaces, and those surfaces were then analyzed with micro-FTIR to correlate contact angle with chemistry. In addition, an image analysis system was used to add the maceral composition effect on chemistry and hydrophobicity. The results show that low- and high-rank coal samples have distinct and opposite trends between functional groups semi-quantitative ratios and contact angle, reflecting rank-dependent effects of chemistry on coal surface hydrophobicity. This work demonstrates that micro-FTIR can be a valuable tool to investigate the hydrophobicity of coal and shows that tracking correlations between chemical groups on the surface of Individual Macerals, and relating them to hydrophobicity is an effective way to build understanding of the effects of coal chemistry on flotation.

  • Influence of maceral composition on geochemical characteristics of immature shale kerogen: Insight from density fraction analysis
    International Journal of Coal Geology, 2012
    Co-Authors: Maria Mastalerz, Agnieszka Drobniak, Arndt Schimmelmann, G.p. Lis, Artur B. Stankiewicz
    Abstract:

    Abstract Variations in the relative proportions of Individual Macerals in shales can significantly influence the geochemical characteristics of bulk organic matter. Density fractions of kerogen from the thermally immature New Albany Shale (Devonian and Mississippian) with contrasting maceral compositions exhibit strong geochemical differences. The parental shale is characterized by a vitrinite reflectance (Ro) of 0.45%, a total organic carbon content of 13 wt.%, and a sulfur content of 6.2 wt.%. Organic matter is dominated by amorphinite and alginite, with vitrinite and inertinite accounting only for 1% by volume. Alginite-dominated density fractions (density ca. 1.0–1.15 g/cm3) contain significantly more aliphatic hydrogen, a stronger carboxyl/carbonyl contribution, and reduced Fourier transform infrared spectroscopy absorbance in the 1000 to 1100 cm− 1 region assigned to ether bonds (C O C), as compared to the amorphinite-dominated density fraction (density ca. 1.2–1.6 g/cm3). Aromaticity generally increases from alginite-dominated to amorphinite-dominated fractions. Density fractions dominated by amorphinite are more deuterium-depleted (δDn values of nonexchangeable hydrogen up to − 105‰) than alginite-rich density fraction (δDn values reach − 90‰). In contrast, changes in relative proportions of alginite and amorphinite in the New Albany Shale do not significantly affect the amount of isotopically exchangeable hydrogen in total hydrogen (i.e., hydrogen exchangeability). Alginite is relatively 13C-enriched, whereas density fractions having a high content of amorphinite are relatively 13C-depleted. Our results suggest that even small bulk geochemical and isotopic differences can gain relevance after deconvolution from maceral-related variability. The masking influence of maceral abundance patterns must be considered when interpreting bulk geochemical data as paleoenvironmental proxies. The findings of this study on shale and Type II kerogen are relevant for all types of kerogens in sediments and rocks.

  • Characterization of chemical functional groups in Macerals across different coal ranks via micro-FTIR spectroscopy
    International Journal of Coal Geology, 2012
    Co-Authors: Yanyan Chen, Maria Mastalerz, Arndt Schimmelmann
    Abstract:

    Abstract Fourier transform infrared spectra of a suite of coals of varying rank from peat to anthracite were obtained via reflectance micro-FTIR and traditional KBr pellet techniques. With increasing rank of coal samples, KBr-FTIR spectra exhibit rising aromaticity (ratio of CH ar at 3000–3100 or 700–900 cm − 1 versus CH al at 2800–3000 cm − 1 ) and enhanced condensation of aromatic rings (ratio of CH ar versus C=C at ~ 1600 cm − 1 ), whereas the aliphatic chain length (ratio of CH 2 /CH 3 at 2800–3000 cm − 1 ) and the ‘C’ factor (ratio of C=O at ~ 1710 cm − 1 versus (C=O + C=C)) decrease. The ratio of CH al /(CH al  + C=C) (i.e., the ‘A’ factor), which reflects the hydrocarbon-generating potential, initially rises at low rank and later decreases in higher-rank coal= ( R o > 0.98%). However, the trends of these semi-quantitative FTIR ratios are difficult to trace in high-rank coals ( R o > 1.50%), probably attributable to limited peak areas and enhanced uncertainties in ratio calculations. The overall evolutionary trends of functional group abundances in bulk coals and their Individual Macerals are similar; distinct differences in chemical properties, however, exist among maceral groups, and these variations depend on rank. Within the three maceral groups, liptinite generally exhibits the lowest aromaticity, the longest aliphatic chains having the least amount of branching, and the highest ‘A’ factor testifying to the highest hydrocarbon-generating potential. In contrast, inertinite shows the highest aromaticity and degree of condensation of aromatic domains and the lowest hydrocarbon-generating potential. Vitrinite generally exhibits intermediate characteristics between liptinite and inertinite. Compared to KBr spectra, micro-FTIR spectra present better detection capability and stronger signals in the 700–900 cm − 1 region, which allows for close investigation of aromatic CH x out-of-plane deformation modes. The rapid decrease in the peak area ratio at ~ 870 cm − 1 /~ 750 cm − 1 in vitrinite from peat to low-volatile bituminous coal is followed by a significant increase after R o > 1.50%, which indicates the dominance of highly substituted aromatic rings in immature coal's structure, while condensed aromatic domains become prevalent in higher-rank coals (semi-anthracite and anthracite). The increase in coal aromaticity during coalification is attributed largely to the accumulation of condensed aromatic structures in more mature coals. Novel reflectance micro-FTIR mapping is a promising and powerful tool providing high-resolution information on chemical properties of coal Macerals relating to parent material and coalification.

  • Variations in pore characteristics in high volatile bituminous coals: Implications for coal bed gas content
    International Journal of Coal Geology, 2008
    Co-Authors: Maria Mastalerz, Agnieszka Drobniak, Dariusz Strąpoć, Wilfrido Solano Acosta, John A. Rupp
    Abstract:

    Abstract The Seelyville Coal Member of the Linton Formation (Pennsylvanian) in Indiana was studied to: 1) understand variations in pore characteristics within a coal seam at a single location and compare these variations with changes occurring between the same coal at different locations, 2) elaborate on the influence of mineral-matter and maceral composition on mesopore and micropore characteristics, and 3) discuss implications of these variations for coal bed gas content. The coal is high volatile bituminous rank with R 0 ranging from 0.57% to 0.60%. BET specific surface areas (determined by nitrogen adsorption) of the coals samples studied range from 1.8 to 22.9 m 2 /g, BJH adsorption mesopore volumes from 0.0041 to 0.0339 cm 3 /g, and micropore volumes (determined by carbon dioxide adsorption) from 0.0315 to 0.0540 cm 3 /g. The coals that had the largest specific surface areas and largest mesopore volumes occur at the shallowest depths, whereas the smallest values for these two parameters occur in the deepest coals. Micropore volumes, in contrast, are not depth-dependent. In the coal samples examined for this study, mineral-matter content influenced both specific surface area as well as mesopore and micropore volumes. It is especially clear in the case of micropores, where an increase in mineral-matter content parallels the decrease of micropore volume of the coal. No obvious relationships were observed between the total vitrinite content and pore characteristics but, after splitting vitrinite into Individual Macerals, we see that collotelinite influences both meso- and micropore volume positively, whereas collodetrinite contributes to the reduction of mesopore and micropore volumes. There are large variations in gas content within a single coal at a single location. Because of this variability, the entire thickness of the coal must be desorbed in order to determine gas content reliably and to accurately calculate the level of gas saturation.

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  • A study of the kinetic parameters of Individual Macerals from Upper Permian coals in South China via open-system pyrolysis
    international journal of coal geology, 2000
    Co-Authors: Xg Sun, Gy Wang
    Abstract:

    A unique Upper Permian coal, Leping coal, is widely distributed in South China. The coal samples studied in the paper were collected from two mines in the Shuicheng coalfield of Guizhou Province, southwest China. The geochemical works including coal petrography, maceral content, Rock-Eval pyrolysis, and kinetic modelling of hydrocarbon-generating have been carried out on whole coal and Individual Macerals. The higher contents of volatile matter, elemental hydrogen, and tar yield, and the high hydrocarbon generation potential of the Leping coals are attributed to their high content of "barkinite", a special liptinite maceral. The hydrocarbon generation potential of "barkinite" (S-2 = 287 mg/g, hydrogen index (HI)= 491 mg/g TOC) is greater than that of vitrinite (S-2 = 180 mg/g, HI = 249 mg/g TOC), and much higher than that of fusinite (S-2 = 24 mg/g, HI = 35 mg/g TOC). At the same experimental conditions, "barkinite" has a higher threshold and a narrower "oil window" than those of vitrinite and fusinite, and consequently, can generate more hydrocarbons in higher coalification temperature and shorter geological duration. Data from the activation energy distributions indicate that "barkinite" has a more homogenous chemical structure than that of vitrinite and fusinite. The above-mentioned characteristics are extremely important for exploring hydrocarbon derived from the Leping coals in South China. (C) 2000 Elsevier Science B.V. All rights reserved.Energy & FuelsGeosciences, MultidisciplinarySCI(E)EI12ARTICLE3-4293-3034