摘要:

SUMMARYThe Carboniferous sediments of northern England have formed the context for an optical study of the effects of differing geothermal history on the included organic material. In the north of the area, the Northumbrian Trough contains 5000 m of cyclothemic Carboniferous sediments with frequent coals and is probably underlain by Old Red Sandstone rocks. To the south, the Alston Block comprises 1500 m of basically similar Carboniferous sediments underlain by highly metamorphosed Silurian slates and a Caledonoid granite. The contrasting nature of the basements has produced variable geothermal gradients and consequently varying coal rank throughout the Carboniferous succession.Alteration of the coals and dispersed organic matter in the sediments by the intrusion of a quartz dolerite sill, the Whin Sill, during Stephanian times has been closely examined. The optical changes induced by the thermal metamorphism depend on the initial rank of the sediments. It has been possible to deduce rank profiles through the succession at the time of intrusion; these can be closely related to the character of the basement. The area was subsequently subjected to hydrothermal (lead, zinc) mineralization.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1977.tb01120.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SUMMARYPrediction of coke strength based on measurements of vitrinite reflectance and data from group‐maceral analyses requires information about the coking power of the different coal macerals in relation to rank. A range of bases are considered by different individuals to be important in prediction studies, e.g. the optimum ratio of reactive to inert constituents for each ‘V‐step’ (vitrinite oil reflectance step × 10); the proportion of vitrinite and clarite and rank; the amount of inertinite with no consideration given to an optimum ratio of reactives to inerts; the rank with little regard given to varying maceral composition. Entirely satisfactory results can be obtained by all investigators for coke‐strength predictions from certain coals under given coking conditions. For other coals, some of the determined values lie well outside the permissible limits of error. Reasons for these deviations may lie in an erroneous, or at least in an inadequate evaluation, of the different microscopical parameters. With this introduction, different predictive methods are discussed and tested. Limits of applicability are demonstrated. Possible improvements are suggested and questions, which have so far not been answered entirely satisfactorily, are posed. Above all, the underlying importance of light microscopy to a major industrial field i

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1977.tb01121.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SUMMARYCoke texture can be shown to be a factor of prime importance in considerations of coke strength and a method has been developed whereby relevant details of the coke texture can be obtained from the microscopic examination of polished coke sections using a Quantimet 720 image analyser. The specimens examined consisted of 10 mm cylindrical cores of the same type as those used for the diametral‐compression test of tensile strength, the cores being mounted in resin and prepared as polished blocks. For a variety of cokes produced on the laboratory scale, and covering a range of porosity from 40 to 60%, the median sizes of pores and pore walls, as determined under the experimental conditions used, varied from about 50–80 μm and 60–120 μm respectively. The number of pores per field of view examined, varied widely from 20 to 220 and the average pore perimeter per field analysed, varied from 70 to 140 mm. The results indicated correlations between the median tensile strength and several of the textural parameters, such as the volume porosity and the average pore‐wall

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1977.tb01122.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SUMMARYAn investigation is made of the inherent performance of a high‐resolution transmission electron microscope applied to the study of developing graphitic‐sheet structures in heat‐treated, coal‐tar pitch carbons. Image detail is shown to be highly dependant on instrumental defocus. It is not obvious which form will be assumed by artefacts in these images; consequently, anomalous features are illustrated by reference to a specific electron‐optical case and a corresponding light‐optical analogy. Despite the difficulties associated with locating an optimum level of focus, optical diffractometry confirms that adequate conditions of microscopy are attainable on a routine basis. In a quantitative analysis of morphology in coal‐tar pitch carbons, the technique reveals the cause of incipient, thermally‐induced, molecular distortions which evidently result in a regression in the improvement of order otherwise developing with progressive

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1977.tb01123.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SUMMARYPlant spores and pollen grains were heated to different temperatures, from room temperature to 350°C at atmospheric pressure, in a nichrome‐wire resistance furnace, and to different temperatures from 100 to 500°C at 1 kb pressure in a modified apparatus normally used for triaxial rock‐deformation studies. In the temperature and pressure experiments, the grains were mixed with silica sand and sea water in the proportions of 1:4:5. For optical microscopy, the pollen grains were mounted in glycerine jelly: for SEM, they were mounted on aluminium stubs rinsed with water and sputter‐coated with gold. STEM and HVEM were used on thick sections of spores ofLycopodium clavatumembedded in Epon‐Araldite.The different layers of the spore or pollen‐grain (i.e. exine+intine) degrade differently. The ornamented part of the exine (the sexine−mainly composed of sporopollenin, lipids and polysaccharides) begins to degrade at approximately 300–350°C and 1 kb pressure, exposing the non‐ornamented nexine layer. The nexine seems able to withstand high temperatures and pressures. Between 300 and 500°C with 1 kb pressure, the grains begin to form an amorphous mass. Compared with other work in which the outer exine layer ofL. clavatumwas removed by oxidation with ozone, here the same layer was gradually removed by pressure and temperature effects. The smell of phenolic compounds is very prominent at higher temperatures (400°C with 1 kb pressure and upwards) and production of other gas, unidentified so far, is evident from about 300°C and 1 kb pressure.The degraded exposed nexine layer at 500°C resembles thin plates in the SEM. A similar structure was also found inL. clavatumheated at 300°C and 1 kb pressure. The exposed nexine ofL. clavatumwas sectioned and examined in the TEM, which showed the trilamellar units, of which the main bulk of the nexine is composed, to be very resistant to high temperatures and pressures. STEM and HVEM have been used to study globular structures observed in the

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1977.tb01124.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SUMMARYSpherulitic aromatic structures with relatively simple optical characters that form as a transitional phase in the development of mosaic textures are well known in pitch fractions and certain polymers when carbonized. Their occurrence in coal macerals that soften prior to the formation of a mosaic is less certain. Other spherulitic structures, much larger in size than mesophase spherules, can, however, develop from vitrinites with a high potential fluidity under certain carbonization conditions, when fast heating rates are employed. These bodies, besides displaying optical characters that indicate structural symmetry, also show mosaic textures.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1977.tb01125.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SUMMARYBlack, viscous, subelastic elateritic hydrocarbon associated with ‘peach’ (tour‐maline‐quartz‐chlorite‐rock), forms a seepage in a movement zone in granite near its contact with killas at South Crofty Mine, near Redruth, Cornwall. The hydrocarbon is paragenetically associated with granular pyrite, but infiltrates the ‘peach’. Readily soluble in aromatic and halogenated alkane solvents, the hydrocarbon is insoluble in paraffinic solvents suggesting a condensed structure. Infrared spectroscopy and N.M.R. spectroscopy indicate a mainly aliphatic content with some aromatic component. Both carbonyl (>C=0) and hydroxyl (−OH) functions are present. Strong methyl absorption bands show a considerable amount of branching or methyl side groups. Gel permeation chromatography and visual spectrometry show no detectable porphyrins. The origin of the hydrocarbon is uncertain; it may represent a distillate of carbonaceous killas (Mylor Series) entrapped in granite at depth, but an abiogenic origin ca

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1977.tb01126.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY