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1.
Rank evaluation of South Brazilian Gondwana coals according to the American (American Society for Testing and Materials, ASTM) and German (Deutsche Industrie Normen, DIN) standard specifications or on the basis of Alpern's Universal Classification has too often led to conflicting results.When any attempt is made to determine the rank of Brazilian coals by using methods established for the Northern Hemisphere coals, two sorts of difficulties arise: namely, (1) the reflectence measurements do not indicate the real degree of coalification of the organic matter because of the liptinitic impregnations of the vitrinites, and (2) random reflectance values (Rran, moisture, volatile-matter and carbon contents as well as the calorific value do not correlate when plotted on the ASTM and DIN classification schemes.In addition, when rank determinations are carried out by using fluorescence measurements and geochemical analyses the results are at variance in relation to those determined by the conventional chemical and physical parameters.It is suggested that the rank evaluation of South Brazilian coals is far more meaningful if carried out by reflectance measurements on vitrinites along with fluorescence measurements on sporinites, alginites and coal extracts. 相似文献
2.
Miroslav Košina 《International Journal of Coal Geology》1984,4(3):263-280
Proposals for new scientific classifications of bituminous coals are based on micropetrographic parameters, i.e. vitrinite reflectance as a criterion of the coalification and maceral composition, presupposed to express the connection between the genetic peculiarities and physical, chemical, and technological properties of the coal mass. In the case of coals with high inertinite contents, however, the utilizability of these parameters meets with difficulties resulting from the subjectivity of determining the different transitional material and from insufficient knowledge of inertinite behaviour at higher temperatures. In the case of the maceral-variable bituminous coals produced in the Ostrava-Karviná Coal Basin, these insufficiencies are not important since it is especially the expression of the variability of the properties of isometamorphic vitrinites, which has decisive effects up-on the course of the thermo-chemical transformations, that is of principal importance to the scientific classification of these coals.In the first approximation, the properties of isometamorphic vitrinites may be expressed by the parameter (H/O)at, closely connected with fluidity. While the micropetrographic parameters reflect in particular the peculiarities in the chemical structure of the aromatic parts of coal macromolecules, the parameter (H/O)at expresses the properties of the non-aromatic structures of vitrinite, significantly affecting the course of its thermal degradation. The experimental results show that the value of the parameter (H/O)at, fluidity and the course of degassing the coal of a lower coalification are independent of the maceral composition and vitrinite reflectance; also that the caking and coking properties of low-rank coals are especially dependent on the parameter (H/O)at and partially on the micropetrographic parameters. All these facts should be taken into consideration in preparing new scientific classifications of bituminous coals. 相似文献
3.
The Py-GC/MS results of the study carried out on two groups of vitrinites (perhydrous and non-perhydrous) of different age and properties and on a trimaceralic coal associated with one of the perhydrous group are discussed. Such a study provides information about the effect of natural hydrogen enrichment on vitrinite structure at the molecular level. Moreover, the influence of the different conditions in the sedimentary environment on the chemical structure of the vitrinite is also discussed. This influence is inferred through differences in the distribution and relative amount of phenolic compounds found in the pyrolysates from two samples of two different coal-beds in the same basin but formed under different paleoenvironmental conditions. For vitrinites with a high H/C atomic ratio, despite having a strong perhydrous character, their pyrolysates exhibit the highly phenolic signature typical of lignin-derived material with only minor aliphatic compounds. Thus, the major chemical structural elements in these vitrinites are simple phenols with a high contribution of para alkyl-substituted derivatives. However, there is no parallel relationship between the evolution of the oxygenated functionalities and the reflectance values. From the results obtained a coalification pathway where hydrogenation processes predominate over thermal ones is proposed. The presence of resin-like substances and/or oils (which are two of the causes of natural hydrogen enrichment) in the molecular structure of vitrinites have, therefore, affected the normal evolution of the lignin and contributed to the special properties of this type of materials. 相似文献
4.
煤镜质组反射率光性组构变形实验研究 总被引：5，自引：0，他引：5
不同煤级煤的高温高压实验表明，在温、压和差异应力作用下，煤镜质组反射率值和各向异性都有一定程度增加，变形越强烈，增加越明显，尤其在中煤级中、晚期阶段更是如此。在变形过程中，反射率主轴将发生有规律的偏转，变形越强烈，最小反射率主轴越接近于最大挤压应力方向。随着变形的增强，镜质组反射率椭球由单向伸长同压缩型转化。 相似文献
5.
A.G. Borrego C.V. Araujo A. Balke B. Cardott A.C. Cook P. David D. Flores M. Hmor-Vid W. Hiltmann W. Kalkreuth J. Koch C.J. Kommeren J. Kus B. Ligouis M. Marques J.G. Mendona Filho M. Misz L. Oliveira W. Pickel K. Reimer P. Ranasinghe I. Surez-Ruiz A. Vieth 《International Journal of Coal Geology》2006,68(3-4):151-170
The development of a qualifying system for reflectance analysis has been the scope of a working group within the International Committee for Coal and Organic Petrology (ICCP) since 1999, when J. Koch presented a system to qualify vitrinite particles according to their size, proximity to bright components and homogeneity of the surface. After some years of work aimed at improving the classification system using photomicrographs, it was decided to run a round robin exercise on microscopy samples. The classification system tested consists of three qualifiers ranging from excellent to low quality vitrinites with an additional option for unsuitable vitrinites. This paper reports on the results obtained by 22 analysts who were asked to measure random reflectance readings on vitrinite particles assigning to each reading a qualifier. Four samples containing different organic matter types and a variety of vitrinite occurrences have been analysed. Results indicated that the reflectance of particles classified as excellent, good or poor compared to the total average reflectance did not show trends to be systematically lower or higher for the four samples analysed. The differences in reflectance between the qualifiers for any given sample were lower than the scatter of vitrinite reflectance among participants. Overall, satisfactory results were obtained in determining the reflectance of vitrinite in the four samples analysed. This was so for samples having abundant and easy to identify vitrinites (higher plant-derived organic matter) as well as for samples with scarce and difficult to identify particles (samples with dominant marine-derived organic matter). The highest discrepancies were found for the organic-rich oil shales where the selection of the vitrinite population to measure proved to be particularly difficult. Special instructions should be provided for the analysis of this sort of samples. The certainty of identification of the vitrinite associated with the vitrinite reflectance values reported has been assessed through a reliability index which takes into account the number of readings and the coefficient of variation. The same statistical approach as that followed in the ICCP vitrinite reflectance accreditation program for single seam coals has been used for data evaluation. The results indicated low to medium dispersion for 17 out of 22 participants. This, combined with data from other sets of comparative analyses over a long period, is considered an encouraging result for the establishment of an accreditation program on vitrinite reflectance measurements in dispersed organic matter. 相似文献
6.
A series of hand-picked vitrinite samples from the Lower Kittanning Seam, Pennsylvania have been examined using quantitative pyrolysis-gas chromatography. These vitrinites ranged in rank from 0.59 to 1.71% reflectance, a rank range from high volatile C bituminous to low volatile bituminous. High molecular weight pyrolysis products included alkyl aromatic and phenolic compounds. Attempts have been made to correlate the pyrolysis product composition to rank parameters including vitrinite reflectance, volatile matter yield, carbon content, atomic H/C ratio and Rock-Eval determined Tmax. Total yield of phenols was found to be strongly and inversely rank related. A clear relationship between C8 alkyl-benzene yield and rank was not found for the sample set. 相似文献
7.
Bimala P. Baruah Arpita Sharma Binoy K. Saikia 《Journal of the Geological Society of India》2013,81(5):713-718
An attempt has been made to study the petro-chemical characteristics of some high sulphur sub-bituminous coal samples from Makum coalfield, Assam, India. The proximate and ultimate analyes were carried out and forms of sulphur were determined and their relationships with the Maceral constituents (vitrinite, liptinite, and inertinite) were investigated. The macerals (vitrinite+liptinite+inertinite) have significant relationships (R2>0.500) with volatile matter and carbon, whereas weak correlations were seen with rest of the physico-chemical characteristics of the coals. The study reveals that these coals are rich in vitrinites and sulphur and are aromatic in nature. These coals have good hydrocarbon potential. 相似文献
8.
9.
W. Kalkreuth N. Sherwood G. Cioccari Z. Corrêa da Silva M. Silva N. Zhong L. Zufa 《International Journal of Coal Geology》2004,57(3-4):167-185
Combining vitrinite reflectance (VR) and fluorescence alteration of multiple macerals (FAMM) analyses provide insights into the chemical nature of vitrinites (i.e., perhydrous vs. orthohydrous vs. subhydrous compositions) in Permian Gondwana coals of the Paraná Basin, Brazil. The FAMM-derived equivalent VR (EqVR) values and relationships with VR can be determined according to calibration curves based largely on Permian Gondwana coals of eastern Australia.The analytical results indicate that vitrinites in the Paraná Basin coals studied generally range from orthohydrous to perhydrous, with interpreted VR suppression ranging up to 0.2% absolute for the most perhydrous case. The EqVR values of the Santa Catarina coals, which range from about 0.85% to 0.95% differ from VR values by about 0.10–0.15% absolute, potentially having significant implications on coal utilization.The causes of vitrinite reflectance suppression in the Paraná Basin coals are as yet poorly understood, but are likely to be related to a combination of factors. 相似文献
10.
The Stephanian Ciñera-Matallana Basin of NW Spain comprises 1,500 m of alluvial to lacustrine coal-bearing sediments, which were deposited in a late Variscan transtensional/transpressional pull-apart setting. The relationship between coalification pattern and rock deformation was evaluated by measurements of the anisotropy of vitrinite reflectance (AVR). The AVR ellipsoids reveal both pre-tectonic elements related to the bedding fabric and syn-tectonic elements related to folding, producing biaxial ellipsoid shapes with the maximum reflectance parallel to fold axes. The mean coalification gradient for the Stephanian succession is about 0.62 %Rr/km. Calculations of the mean palaeo-geothermal gradient are presented on the basis of three different empirical equations. A palaeo-geothermal gradient of 85 °C/km is considered the most realistic, with an overburden of about 1,000 m. 1-D numerical modelling of the burial history results in two possible scenarios, the most preferable involving a palaeo-heat flow of 150 mW/m2 and an overburden of ca. 1,050 m. These results indicate that maximum coalification was related to a localised but high palaeo-heat flow/-geothermal gradient. The anisotropy of vitrinite reflectance highlights the interactive and transitional nature of sedimentary compaction and rock deformation on the maturation of organic material within strike-slip fault zones. 相似文献
11.
To help in ascertaining methane content of lignite reservoir in China,the isothermal ad-sorption measurements of methane have been performed on moisture-equilibrated coals of some typical lignite-bearing basins,which comprise maximum reflectance of vitrinite(Ro,max) ranging from 0.24% to 0.50%.Related to other coal properties,our analysis shows that methane adsorption of lignite is mainly affected by coalification,as well as by maceral composition,moisture content,and seam temperature.Maximum methane capaci... 相似文献
12.
应用高分辨率透射电镜研究变质系列镜质体和丝质体以及热解碳的物理结构特征表明,随煤级增高,镜质体的基本结构单元(BSU)的平均长度及缩聚芳香层平均环数NC呈增加的趋势;衍射环数增多,环的弥散程度减小,最终出现弧状;表明镜质体的BSU在变质过程中长大,定向性增强,VRo,max=6.50％是阶跃点,当VRo,max>6.50％,BSU突然定向排列。获得了很难获得的低煤化烟煤(VRo,max=0.66％)的高分辨图像,它的BSU尺寸小,无序排列。对丝质体和热解碳高分辨图像的首次研究发现,前者有序性差,随煤级演化的速度较镜质体慢,后者有序性好。 相似文献
13.
n-Alkanes in the soluble organic matter extracted from a series of vitrinite and sporinite concentrates have been analysed by gas chromatography. The macerals were isolated from coals ranging in rank from 77.1% to 86.6% carbon (vitrinite: dry, ash-free), and yields of n-alkanes ranged from 10 to 580 ppm for vitrinites and from 20 to 970 ppm for sporinites. The maximum yields were found at a rank of 85.4% C from vitrinites and 86.6% C from sporinites.Distribution maxima of the n-alkanes, as shown by gas chromatography, range from C27 and C29 at lower ranks to as low as C16 at higher ranks. The distributions also show a progressive decrease in the preference of odd-carbon-number homologues with increasing rank. Virtually smooth distributions were attained in high-volatile bituminous A coals. Quantitative data show that the loss of the odd-carbon-number preference occurred, for the most part, while individual long-chain homologues increased in concentration.There is a progressive increase in the amounts of shorter-chain n-alkanes with increasing rank. It is suggested that sequential processes may have occurred whereby the rate of formation of long-chain n-alkanes in high-volatile bituminous A rank macerals becomes slower than their rate of subsequent fragmentation to shorter chain lengths. Consequently, assuming derivation from the insoluble maceral matrices, the chain-length distributions of parent n-alkyl structures within the insoluble material may retain characteristics pertaining more to the nature of the source organic matter at the time of deposition than do the extractable n-alkane patterns, especially at higher ranks. 相似文献
14.
低变质煤的有机地球化学指标,如“A”/Cor,“H”/Cor,IH,T（max）OEP,Pr/Ph,S1+S2,C3-菲/总烷基菲等随其在泥炭化过程中经受的氧化还原作用程度的变化而呈规律性变化,显示了氧化还原作用的各种特征.氧化作用以脱去一个至多个碳原子的脱羧基作用或断裂作用的形式,改变正烷烃,类异戊二烯烷烃和烷基菲的组成。并在其对残余部分性质所给予的影响的意义上,可被视为一种“超前煤化作用”。还原作用促进有机质向烃转化,随还原作用加深而发生的镜质组更加富氢的变化比镜质组数量的变化更能提高煤的产烃潜量。只有在查明了煤氧化还原程度的前提条件下,应用这些指标评价成熟度才可能更为准确。 相似文献
15.
华北太原组镜质组中的超微类脂体及其煤性质异常原因 总被引：1，自引：0，他引：1
利用超薄切片透射电镜分析技术，对华北太原组和山西组煤中镜质组的超微结构和组分进行了分析，确认太原组镜质组中含有较丰富的超微类脂体，且超微类脂体主要来自菌藻类，山西组和太原组镜质组中超微类脂体数量存在明显差异。证实镜质体中超微类脂体数量和其化学性质紧密相关。从超微组分层次解释了山西组和太原组镜质组性质差异的原因，并分析讨论了太原组煤性质异常性的原因和煤还原程度问题，提出成煤过程中明显菌藻类低等生物贡献是太原组煤性质异常的一个重要原因。 相似文献
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17.
This paper presents an experimental investigation of coal rank and maceral composition influences on the coal mechanical behaviors. The complete stress–strain behavior, uniaxial compressive strength, Young's modulus, and acoustic compressional velocity were measured and correlated to coal ranks and microstructures. The test results show that coal is an elasto-brittle geo-material and its uniaxial compressive strength and Young's modulus increase as coal rank increases. This occurs because as vitrinite reflectance or coal rank increases, coal has less microporous structure and thus higher uniaxial compressive strength. Therefore, using vitrinite reflectance value instead of vitrinite content is advantageous for correlating coal strength. The experimental results also demonstrate that compressive strength and Young's modulus have positive exponential correlation, even for different types of coal. Therefore, the compressive strength of coal is highly related to its Young's modulus. The uniaxial compressive strength and acoustic compressional velocity of coal are also correlated, but a single correlation does not exist for different coal ranks; instead, different relationships occur for different types of coal. 相似文献
18.
为了探讨不同煤级煤储层中游离气含量分布特征,本文基于游离气主要存在于煤孔隙中的认识,优化了游离气含量估算方法,并利用全国典型含煤地区包含从褐煤到无烟煤的42组不同煤级煤的煤层气参数测试数据,采用优化的游离气含量估算方法计算了不同煤样的游离气含量,并与解吸气含量结果进行了比较。结果表明:煤中游离气含量所占总气含量的比例随镜质体平均最大反射率增高呈减小趋势,在褐煤到无烟煤三号阶段的所占比例分布在2.13%~33.25%;游离气含量和解吸气含量与镜质体平均最大反射率关系均呈"双峰"特征,但双峰峰值大小顺序正好相反,游离气含量在肥煤阶段的峰值高于无烟煤三号阶段,总气含量与镜质体平均最大反射率关系主要受控于解吸气含量。 相似文献
19.
Palaeo-heat flow values and thicknesses of eroded Permo-Carboniferous sediments in the Saar Basin were evaluated using one dimensional thermal modelling techniques. Thermal, burial and erosion histories for 16 wells were calibrated by comparing measured and calculated vitrinite reflectance using the kinetic EASY%Ro algorithm and by comparing measured and calculated temperature data. On the basis of 37 wells, coalification maps were constructed revealing a syn-kinematic coalification pattern. Thermal maturity of the sediments can only be explained by deep burial and moderate heat flows during time of maximum burial, i.e., in the Permo-Carboniferous. Calculated heat flow data range between 50 and 75 mW/m2, which implies a crustal thickness between 30 and 40 km during the time of maximum burial. These values are in accordance with the geodynamic setting of the basin. The influence of the Permo-Carboniferous volcanism on the palaeo-temperature distribution was overwhelmed by the subsequent deep burial. During Permian times, between 1800 and 3000 m of Permo-Carboniferous sediments were eroded. Different sedimentation and erosion histories are characteristic for anticlines and synclines, respectively. 相似文献
20.
The Jewel seam of the Cadomin area is complexly folded and cut by several thrust faults. Vitrinite reflectance anisotropy was determined from twenty oriented coal blocks, collected from various structural positions. Five of the blocks have uniaxial anisotropies, five have biaxial positive anisotropies, the remaining ten are biaxial negative. The biaxial coals display maximum reflectance axes parallel to nearby fold axes, which suggests a relationship between vitrinite anisotropy and deformation. The biaxial vitrinite reflectance ellipsoids result from superposition of tectonic strains on a primary, sedimentary burial related, uniaxial anisotropy. A tectonic stress field was probably present during the later stages of sedimentary burial and subsequent deformation.Coalification resulted largely from pre-deformational, sedimentary burial, but the final coalification stage was syn-deformational, as illustrated by the intersection of isorank surfaces and the Jewel seam and the biaxial vitrinite reflectance anisotropy. 相似文献