British Coals Research Articles

Las colonias francesas dentro de la ecología-mundo (1830-1962): el caso de los combustibles fósiles, los bosques y las plantaciones tropicales en Argelia y Vietnam

Los imperios coloniales jugaron un papel importante en la historia del Capitaloceno a través de la apropiación y explotación de los recursos naturales baratos, de la mano de obra y las energías baratas del mundo extraeuropeo, pero también por su producción de las naturalezas capitalizadas dentro de él, y, más ampliamente su coproducción de un mundo ecológico caracterizado por intercambios económicos y ecológicos desiguales a escala global. Basado en una problemática resultante del trabajo de Jason Moore, una reinterpretación de la historiografía existente y un trabajo de archivo, este artículo muestra que, si bien es esclarecedor comprender la historia de los combustibles fósiles, los bosques y las plantaciones de Argelia (1830-1962) y de Vietnam (1858-1954) en términos de ecología-mundo, su contribución al desarrollo de la ecología-mundo debe examinarse a la luz de las especificidades de cada colonia y de cada sector. En primer lugar, hay que matizar la hipótesis de una producción colonial de combustibles fósiles que sería sistemáticamente barata y destinada a los centros capitalistas occidentales de la ecología-mundo, no correspondiendo esta hipótesis ni al carbón argelino (caro y usado localmente) ni a los hidrocarburos argelinos (caros y exportados principalmente a Francia) ni al carbón vietnamita (barato pero exportado al sudeste asiático). Entonces, la historia conjunta de las plantaciones de caucho vietnamitas y la agricultura colonial argelina revela una capacidad desigual y nunca absoluta de los colonizadores franceses, siempre dependientes de las condiciones ecológicas locales, para crear naturalezas capitalizadas que generen productos tropicales baratos. Finalmente, el estudio combinado de la explotación colonial de los recursos forestales en Argelia y Vietnam permite mostrar hasta qué punto el ecologismo manifestado por los colonizadores franceses, en particular el de las administraciones forestales coloniales, no obstaculizó la producción. Para la ecología-mundo, este análisis, evidentemente, merecería ser profundizado por nuevos estudios de caso, pero constituye, sin embargo, un primer vistazo a la compleja inserción histórica de las colonias francesas en el mundo ecológico.

A thermal maturity map based on vitrinite reflectance of British coals

A compilation of new and previously published vitrinite reflectance (R 0 ) data from Carboniferous coals constitutes the most comprehensive map of reflectance across Great Britain. Values of R 0 range from 0.38 to 3.29%, recording an ambient thermal maturity in the early oil window (standard reference point for reflectance studies), modified by elevated heat flow in northern England and along the Variscan orogenic front. The map provides a context for other geological datasets. Supplementary material: A statistical summary of vitrinite reflectance data is available at https://doi.org/10.6084/m9.figshare.c.4529969

Selenium and tellurium concentrations of Carboniferous British coals

Standard mode and collision/reaction cell mass spectroscopy methods have been utilized in order to overcome spectral interferences and provide ultra‐low quantification of selenium (Se) and tellurium (Te) in British Carboniferous coals for the first time. The accurate detection of Se and Te in coals is becoming increasingly important, as coals and pyrite have been identified as potentially significant trace element sources. The mean Se concentration of British coals bear comparison to that of world coals, with anomalous Se content (concentrations above 4 mg/kg) across westerly exposures, often coinciding with high sulphur (S) content and visible pyrite. New Te data for British coals gives a mean concentration of 0.02 mg/kg, with anomalous Te in Ayrshire. There is a positive correlation in the Te/Se ratio across the sample set. The close relationship between Se and Te, as well as Se–Te with both early syngenetic and later cleat‐filling pyrite, confirms an important role for sulphides in Se and Te sequestration in British coals. The high Se‐Bowland Shale and/or Ordovician volcanics may have provided the trace element source for British coals of similar or younger age. Regional intrusive activity (shallow tabular intrusions or more extensive plutons) and episodes of intense deformation can alter the thermal maturity of coals and may have driven the movement of trace element‐rich fluids through strata, locally enriching coals in Se and Te.

High Pressure Oxydesulphurisation of Coal—A Parametric Study

The current study is focused on controlling sulphur emissions by pre-treating coal to remove sulphur prior to combustion using the oxydesulphurisation technique. Three British coals were chosen for the study. Working with these coals gave a better insight to the oxydesulphurisation reactions for pyritic and organic sulphur. Effect of air and oxygen pressure in a fixed time interval on sulphur removal was studied by series of experimental runs at various temperatures. Heating value recoveries were significant. Increase in oxygen content is reported as a measure of carbon loss. The coal samples were analyzed according to British standard methods. Experimental results demonstrate that the sulphur removal was enhanced with the increase in air pressure, particularly up to 100 bars, with only a small decrease in calorific value at a particular temperature. Increasing temperature was witnessed to be more important in sulphur removal than increasing pressure.

Mineralization episodes and their concentration sites in a typical British coal

Twenty four (24) coal samples from the eight (8) working collieries of Northumberland coalfield, England, have been studied with the view to analyzing the possible location/concentration of the mineral species in coals. The results of the study showed that their clay mineral suites dominated by kaolinitic types are disseminated products at maceral boundaries, desiccation cracks and at times fissures with no established genetic evidence. The other widespread variety of mineral occurrences, notably calcite, siderite and sometime pyrite in the coal basin and traceable to precipitates in various joints, cleats, cell voids and lumens are associated/formed during epigenetic mineralization episode (post depositional phase), when the macerals have differentiated into their various entities. More importantly, these mineral concentration appears to have been partly or wholly controlled by the semifusinite/fusinite macerals (i.e. particularly those exhibiting “Bogenstruktur”) as the preferred traps and/or infills for coals. With the exception of the nodular pyrite that is said to be linked to both vitrinitic and sometimes liptinitic macerals and are traceable to syngenetic mineralization episodes, the euhedral type pyrite demonstrates a complete unique behaviour by their infill of semifusinite/fusinite macerals which suggests the timing to be of post-depositional phase.KEYWORDS: British coals, Mineral species, Concentration sites

00/02261 Geological controls on the sulfur distribution in British carboniferous coals: a review and reappraisal

The Namurian and lowest Westphalian beds of the Millstone Grit are mapped between Brynmawr and Blorenge, South Wales. It is shown that a phase of secondary dolomitisation is related to zones of close jointing of post-Carboniferous age. This has led to easier weathering of the more friable dolomite which in turn has resulted in irregularities along the Millstone Grit-Carboniferous Limestone junction. Details of an easterly directed overstep of Namurian B (R2) age are described together with a further possible overstep of early Westphalian (lenisulcata Zone) age.

Geological controls on the sulphur distribution in British Carboniferous coals: a review and reappraisal

The very extensive literature on sulphur in peats and coals is reviewed and four case histories from British coalfields are considered. In the Parkgate seam (Langsettian) from the Nottinghamshire coalfield, the variation in the total sulphur content is attributed to pyritic sulphur, with organic sulphur also significant but showing a smaller variation. Sulphate sulphur is negligible. There is a spatial variation in the sulphur concentrations in individual sections (plies) of the Parkgate seam, but this is unrelated to other sections of the seam and to identifiable post-depositional controls, thereby providing indirect evidence of a depositional control on sulphur incorporation. In the Main Bright (Duckmantian, North Derbyshire coalfield) and Threequarters seams (Langsettian, North Derbyshire–Nottinghamshire coalfields), the depositional control is shown to be related to contemporaneous channels. There is a hierarchy of channels and it is concluded that these provided access of more saline waters into the peat mire. Coals associated with marine bands often show high sulphur contents, but there are exceptions, particularly in the Scottish Namurian as exemplified by the Upper Hirst seam where it is thought that there was no contemporary ingress of saline waters. Three Westphalian depositional provinces are recognised on the basis of channel sandstone loci and there is the possibility that different source areas influenced the salinity/sulphate content in the mires. There is some evidence of regional differences in the sulphur content of British coals, which is consistent with the distribution of the three provinces. On the other hand, there is irrefutable evidence that access of seawater leads to high sulphur coals and possibly the marine influence was more pervasive than is generally recognised. There is supporting geochemical evidence of enrichment of trace elements in coals which is indicative of a seawater source.

The lead content and isotopic composition of british coals and their implications for past and present releases of lead to the UK environment

More than 60 coal samples, predominantly from the principal coalfields of England and Wales (25) and Scotland (30), were analysed for lead by AAS and for stable lead isotopes by ICP‐MS. While the average lead content of Scottish coal, 23.9 mg kg−1, was more than double that of coal from England and Wales, 11.0 mg kg−1, the corresponding mean 206Pb/207Pb ratios (± 1 s.d.) were nearly identical, at 1.181±0.011 and 1.184±0.006, respectively. In the light of the lead isotopic signatures of British coals and of both indigenous (206Pb/207Pb ∼ 1.17) and imported Australian (206Pb/207Pb ∼ 1.04) lead ores, an approach based on estimated lead emissions from these sources and the deconvolution of the historical lead and 206Pb/207Pb records preserved in lake sediments, peat bogs and archival herbage material indicates that coal combustion became an increasingly significant contributor to atmospheric lead deposition in the UK during the period 1830–1930, especially after the onset of England’s decline as a major location of lead mining and smelting in the late‐19th Century. Since 1930 and the introduction of leaded petrol, the atmospheric 206Pb/207Pb ratio in the UK has been strongly influenced by car‐exhaust emissions of comparatively 206Pb‐depleted lead of predominantly Australian origin, counter‐balanced to some extent by coal‐combustion emissions of lead, although these have fallen dramatically since the mid‐1950s. Nevertheless, with the introduction and substantial uptake of unleaded petrol in the UK during the last decade, even the declining releases from coal, along with contributions from other sources, are continuing to affect the atmospheric lead content and 206Pb/207Pb ratio.

The distribution of mineral matter in pulverised coal particles in relation to burnout behaviour

The presence of mineral matter in a pulverised coal particle may affect the behaviour of the particle during combustion, and could influence the level of unburnt carbon in ash experienced in power stations. This paper presents details of a computer-controlled scanning electron microscopy (CCSEM) method of characterising the mineral content of individual pulverised coal particles and describes the distribution of mineral matter in pulverised coal samples. The possible influences of the mineral matter distribution on levels of unburnt carbon are discussed in the light of burnout measurements for the same coal samples. Pulverised coal particles may be divided into three types on the basis of their mineral content: organic-rich particles, organic particles with included minerals, and excluded mineral particles. The relative proportions of these different particle types have been characterised for a suite of 18 power station coals from around the world. Organic-rich particles are the most abundant, and particles containing included minerals form a greater mass fraction of the coals than excluded mineral particles. The excluded mineral particles have a considerably finer size distribution than the particles containing organic material, and the organic-rich particles are generally slightly larger than the organic particles with included minerals. Ranking the coals by degree of mineral-organic association shows a strong separation of coals on a geographical basis. Australian and South African coals show higher levels of mineral-organic association than British and North American coals. Although there are a number of possible mechanisms by which included minerals might modify the combustion behaviour of pulverised coal particles, comparison between the mineral distribution and the combustion performance of these coals does not favour any particular mechanism for influencing levels of unburnt carbon.

97/03452 An evaluation of microwave-driven stannylation followed by in situ119Sn MAS n.m.r. spectroscopy as a probe for hydroxyl functionality in medium-rank British coals and macerals

97/03452 An evaluation of microwave-driven stannylation followed by in situ119Sn MAS n.m.r. spectroscopy as a probe for hydroxyl functionality in medium-rank British coals and macerals

An evaluation of microwave-driven stannylation followed by in situ119Sn MAS n.m.r. spectroscopy as a probe for hydroxyl functionality in medium-rank British coals and macerals

Stannylation of a range of phenolic compounds with Me 3SnCl, Bu 3SnCl and (Bu 3Sn) 2O (TBTO) was carried out under both microwave-driven and conventional conditions. The degree of stannylation was influenced by the steric environment of the OH group, implying that stannylation in comparison with, say, trimethylsilylation of OH groups could help to map the steric environments of phenolic groups in coals. Good maceral separations of Creswell coal and acceptable separations of Cortonwood coal were achieved. The whole coals and the macerals were stannylated with TBTO under microwave-enhanced conditions and the products were examined by 119Sn MAS n.m.r. and X-ray photoelectron spectroscopy. The reaction was confined to surface regions. Differences were found in the behaviour of the macerals. The crystal and molecular structures of the trimethylstannyl derivative of 2,6-diphenylphenol were determined, to establish the validity of the claim to have stannylated model compounds. Molecular parameters were compared with related systems.

96/03710 Viscosity of coal-derived liquids. 1. Application of the model to coal liquid fractions

An investigation of the reaction chemistry of catalysed coal dissolution in recycle solvent in an inert atmosphere was carried out using low-rank British bituminous coals (Point of Ayr clean and Asfordby) and a high-rank coal (Cwm) in a tubing-bomb microreactor (25 cm3 capacity) at different temperatures (300–450°C) and reaction times (15–60 min). The results revealed that the initial rupture of the coal structure is primarily a thermolytic process, largely dependent on the severity of the reaction conditions. The threshold temperature for the dissolution of Point of Ayr (PoA) coal was ∼375°C. The catalyst, Mo-based Akzo-153, did not influence the overall conversion of coal as assessed by quinoline and THF extracts. Above 400°C, however, the catalyst promoted the hydrogenation of coal radicals generated by thermal treatment to yield more low-molecular-weight products, such as oils. The high-rank Cwm coal produced only 37 wt% (daf) of THF extracts, while the PoA and Asfordby coals yielded ∼65 wt%.

96/03699 Separation of iron catalyst from coal liquefaction crude oil with high gradient magnetic separator

An investigation of the reaction chemistry of catalysed coal dissolution in recycle solvent in an inert atmosphere was carried out using low-rank British bituminous coals (Point of Ayr clean and Asfordby) and a high-rank coal (Cwm) in a tubing-bomb microreactor (25 cm3 capacity) at different temperatures (300–450°C) and reaction times (15–60 min). The results revealed that the initial rupture of the coal structure is primarily a thermolytic process, largely dependent on the severity of the reaction conditions. The threshold temperature for the dissolution of Point of Ayr (PoA) coal was ∼375°C. The catalyst, Mo-based Akzo-153, did not influence the overall conversion of coal as assessed by quinoline and THF extracts. Above 400°C, however, the catalyst promoted the hydrogenation of coal radicals generated by thermal treatment to yield more low-molecular-weight products, such as oils. The high-rank Cwm coal produced only 37 wt% (daf) of THF extracts, while the PoA and Asfordby coals yielded ∼65 wt%.

Chlorine In five Illinois coals and three British coals: An X-ray absorption near-edge structure (XANES) spectroscopy investigation

The chlorine (Cl) XANES spectra of five Illinois coals and three British coals, and two series of char samples were examined. The char samples were prepared by step-wise heating of one Illinois and one British coal in air at temperatures from 200 to 650{degrees}C. The Cl XANES spectra for all the coals are similar and chloride anion was determined to be the predominant form of Cl. The identity of the positive counter ions with which the chlorine anions are associated in the coal could not be unambiguously determined from the XANES spectra. Nevertheless, the XANES spectra of the raw coals and their partially combusted char samples show significant changes in the form (and concentration) of Cl with increasing char preparation temperature. The presence of NaCl was observed in the chars from the British sample between 200 to 350{degrees}C but not in the chars from the Illinois sample. These data suggest that the British coal sample may have more chlorides paired with positive sodium ions compared to that in the Illinois coal.

Studies of catalysed, solvent-mediated coal dissolution without H 2 overpressure

An investigation of the reaction chemistry of catalysed coal dissolution in recycle solvent in an inert atmosphere was carried out using low-rank British bituminous coals (Point of Ayr clean and Asfordby) and a high-rank coal (Cwm) in a tubing-bomb microreactor (25 cm 3 capacity) at different temperatures (300–450°C) and reaction times (15–60 min). The results revealed that the initial rupture of the coal structure is primarily a thermolytic process, largely dependent on the severity of the reaction conditions. The threshold temperature for the dissolution of Point of Ayr (PoA) coal was ∼375°C. The catalyst, Mo-based Akzo-153, did not influence the overall conversion of coal as assessed by quinoline and THF extracts. Above 400°C, however, the catalyst promoted the hydrogenation of coal radicals generated by thermal treatment to yield more low-molecular-weight products, such as oils. The high-rank Cwm coal produced only 37 wt% (daf) of THF extracts, while the PoA and Asfordby coals yielded ∼65 wt%.

96/00046 The effect of non-ionic reagent adsorption on the froth structure and flotation performance of two low rank British coals

96/00046 The effect of non-ionic reagent adsorption on the froth structure and flotation performance of two low rank British coals

The effect of non-ionic reagent adsorption on the froth structure and flotation performance of two low rank British coals

In the froth flotation of ultra-fine particles, the recovery and purity of the final product obtained depend largely on the froth structure, which in turn is affected by reagent adsorption on the solids. In this study, ultra-fine particles (5 μm size fractions) of two low rank British coals were used in the flotation tests. The tests were carried out using only one of two different non-ionic reagents; diacetone alcohol and 2-ethyl hexanol. The froth structure can be changed significantly by addition of reagent. It was observed that when the froth structure changes from a spherical to a polyhedral structure that the flotation performance changes significantly. Previous measurements of the internal pore distributions showed marked differences between the Rawdon and Bickershaw coals. Also the flotation performance of each coal differed significantly according to the reagent used. It is postulated that the differing behaviour of the coals can be attributed to the fractional amount of the total reagent adsorbed on the interior pore surfaces.

The adsorption behavior of nonionic reagents on two low rank British coals

The adsorption behavior of nonionic reagents on two low rank British coals

57Fe Mössbauer spectra of some virgin British coals and the products of their partial combustion

Four British coal samples are shown to have pyrite (FeS2) as the principal iron-containing material. On combustion under conditions approximating those in commercial boilers, stoichiometric FeS is formed by pyrolysis and magnetite (Fe3O4) by oxidation. No haematite (Fe2O3) was found, but an additional phase is present which appears to be a high-spin iron(II) sulphide.

Nature of the electron paramagnetic resonance intensity in iodine treated coals

Three British coals and their iodine treated counterparts were examined in order to investigate the increase in electron paramagnetic resonance (e.p.r.) signal intensity that occurs upon iodine uptake. The iodine is not removed by vacuum. Scanning electron microscopy (SEM) results show that the iodine exists in a highly dispersed form. Correlation of elemental analysis and e.p.r. spin density measurements indicates two to ten new spins added per 100 added I 2 molecules. A study of e.p.r. intensity as a function of temperature reveals nearly identical trends for untreated and iodine treated coals. High frequency e.p.r. resolves additional signal at lower fields in the iodine treated samples. Such observations contradict the notion of donor-acceptor complex formation between iodine and aromatic constituents of the coal. Although there is considerable evidence of iodine participation in the formation of this additional signal, it would appear to be of a non-bonding nature.