Application of reflectance parameters in the estimation of the structural order of coals and carbonaceous materials. Precision and bias of measurements derived from the ICCP structural working group

Optical reflectance of vitrinite is one of the fundamental physical properties that have been used for the study of coal and carbonaceous materials. Organic matter in coals and carbonaceous matter consists mainly of aromatic lamellae, whose dimensions and spatial orientation define its internal structure. Various reflectance parameters describe well the average degree of order of the molecular structure of organic matter. Moreover, reflectance parameters are numerical values which characterize the samples unambiguously, facilitating the comparison of the optical properties of different carbonaceous materials as well as comparison between optical parameters and other physical or chemical factors. The focus of this study is the evaluation of the precision and bias of reflectance measurements (R and R) performed by various analysts in different laboratories in order to check the applicability of reflectance parameters to the estimation of the structural order of coals and carbonaceous materials. Additionally, it was desirable to compare reflectance parameters with other parameters obtained by different analytical methods able to provide structural information. The consistency and repeatability of the reflectance measurements obtained by different participants turned out to enable the drawing of similar conclusions regarding the structural transformation of anthracite during heating. Good correlations were found between the reflectance parameters studied and structural factors obtained by comparative methods. The reflectance parameters examined proved to be very sensitive to any changes of the structural order of coals and carbonaceous materials and seem to be a perfect complement to structural studies made by X-ray diffraction or Raman spectroscopy

Development of a petrographic classification of fly-ash components from coal combustion and co-combustion. (An ICCP Classification System, Fly-Ash Working Group – Commission III.)

A new system for the microscopic classification of fly-ash components has been developed by the Fly-Ash Working Group, Commission III of the ICCP and is presented herein. The studied fly-ashes were obtained from the combustion of single coals of varied rank, coal blends, and coals blended with other fuels (biomass, petroleum coke), in different operating conditions and by means of different technologies. Microscopic images of the fly-ash samples were used to test the optical criteria proposed for classifying the fly-ash components. The classification system developed is based on a small number of microscopic criteria, subdivided into six independent levels or categories, three of which are directed at whole particle identification on the basis of nature, origin and type of fly-ash particle, while the other three levels are directed at the smaller section identification on the basis of character, structure and optical texture of unburned carbons. To classify the inorganic components of the fly-ash, the criterion proposed is composition in terms of metallic/non-metallic character. To establish the classification criteria the petrographers involved in the work performed three successive round robins. Evaluation of the results by using firstly descriptive statistics and then the criteria and parameters employed by the ICCP in their accreditation programs indicated that the classification of the fly-ash components was accurate and that there was only a minor bias. The main conclusion of this study was that the proposed criteria are valuable for identifying, and classifying fly-ash components and for describing the optical properties of fly-ash particles

Microscopical characterization of carbon materials derived from coal and petroleum and their interaction phenomena in making steel electrodes, anodes and cathode blocks for the microscopy of Carbon Materials Working Group of the ICCP

This paper describes the evaluation of petrographic textures representing the structural organization of the organic matter derived from coal and petroleum and their interaction phenomena in the making of steel electrodes, anodes and cathode blocks.This work represents the results of the Microscopy of Carbon Materials Working Group in Commission III of the International Committee for Coal and Organic Petrology between the years 2009 and 2013. The round robin exercises were run on photomicrograph samples. For textural characterization of carbon materials the existing ASTM classification system for metallurgical coke was applied.These round robin exercises involved 15 active participants from 12 laboratories who were asked to assess the coal and petroleum based carbons and to identify the morphological differences, as optical texture (isotropic/anisotropic), optical type (punctiform, mosaic, fibre, ribbon, domain), and size. Four sets of digital black and white microphotographs comprising 151 photos containing 372 fields of different types of organic matter were examined. Based on the unique ability of carbon to form a wide range of textures, the results showed an increased number of carbon occurrences which have crucial role in the chosen industrial applications.The statistical method used to evaluate the results was based on the "raw agreement indices". It gave a new and original view on the analysts' opinion by not only counting the correct answers, but also all of the knowledge and experience of the participants. Comparative analyses of the average values of the level of overall agreement performed by each analyst in the exercises during 2009-2013 showed a great homogeneity in the results, the mean value being 90.36%, with a minimum value of 83% and a maximum value of 95%

Development of a petrographic technique to assess the spontaneous combustion susceptibility of Indian coals

Petrographic studies are commonly used categorise the potential utilisation of coals. Eleven coal samples from the jharia coalfield (JCF), india, were studied using petrographic techniques to investigate maceral content, reflectance, and textural characteristics. Multiple test samples of each coal were slowly oxidised under controlled laboratory conditions from an ambient temperature of 30°c to 300°c to investigate the morphology of oxidised coals. The petrographic characterisation of the coals before and after oxidation showed important changes in both morphology and vitrinite reflectance. The oxidation of the coal particles produced three predominant textural changes: particles with homogeneous change of reflectance (HCv), particles with oxidation rims (ORv), and particles with no changes were observed (Uv) respectively. These textural characteristics were used to indicate how particles had interacted with oxygen at low temperatures during the early stages of oxidation. The morphological classification developed provides an alternative method to confirm the susceptibility of a coal to spontaneous combustion. Conventional thermal parameters such as crossing point temperature (CPT) were unable to identify the coals prone to spontaneous combustion. However, certain petrographic parameters could be combined with CPT values to provide a much more accurate measure for susceptibility to spontaneous combustion

Morphological forms of chars in slag and fly ash from the Będzin power station, Upper Silesia, Poland

Combustion of coal is still one of the main sources of energy and electricity in Poland. For cost reasons, and because of the need to protect the environment, it is important to use coal as efficiently as possible. One of the indicators of coal combustion efficiency is the amount of unburned organic matter in slag and fly ash. This organic matter occurs in different morphological forms. This paper provides an overview of the char morphological forms found in slag and fly ash from selected boilers installed in Będzin Power Station (Poland). The relative quantities of particular morphological forms are compared with the maceral composition of the feed coal. The aim is the better understanding of the influence that maceral composition has on combustion performance

Composition and morphology of organic and mineral matter in fly ash derived from bituminous coal combusted in the Będzin power station (Poland)

Fly ash particles formed during coal combustion are composed entirely of organic or/and mineral matter. The proportions of the two components depends on combustion conditions and the presence of minerals in feed coal particles. The aims of this paper are the classification of char morphologies, the quantification of the inert- and semiinert components, and the characterisation of the morphologies and compositions of mineral particles in fly ash from Będzin Power Station, Poland. Various char morphologies are presented and their distribution in individual pulverised fuel boilers is discussed as are the morphologies of mineral particles and the distribution of major and minor elements in different size fractions of fly ash

Classification of liptinite – ICCP System 1994

The liptinite maceral group has been revised by ICCP in accordance with the ICCP System 1994. After the revision of the classifications of vitrinite (ICCP, 1998), inertinite, (ICCP, 2001) and huminite (Sykorova et al., 2005) this liptinite classification completes the revised ICCP maceral group classifications. These classifications are collectively referred to as the “ICCP System 1994”. In contrast to the previous ICCP Stopes Heerlen (ICCP, 1963, 1971, 1975, 1993) this new classification system is applicable to coal of all ranks and dispersed organic matter. The classification as presented here was accepted in the ICCP Plenary Session on September 11, 2015 at the ICCP Meeting in Potsdam. The decision to publish this classification in the recent form was accepted at the ICCP Plenary Session on September 23, 2016 in Houston