Coal analyses components

Determination of a good value for the percent of mineral matter content (% MM) is a very important component of coal analysis. If this quantity cannot be determined directly by the acid demineralization or low-temperature ashing procedure discussed previously, or by other suitable methods, it is possible to calculate a reasonable value for the mineral matter in coal, provided that the necessary data are available. 

We have developed several new measurement techniques ideally suited to such conditions. The first of these techniques is a High Pressure Sampling Mass Spectrometric method for the spatial and temporal analysis of flames containing inorganic additives (6, 7). The second method, known as Transpiration Mass Spectrometry (TMS) (8), allows for the analysis of bulk heterogeneous systems over a wide range of temperature, pressure and controlled gas composition. In addition, the now classical technique of Knudsen Effusion Mass Spectrometry (KMS) has been modified to allow external control of ambient gases in the reaction cell (9). Supplementary to these methods are the application, in our laboratory, of classical and novel optical spectroscopic methods for in situ measurement of temperature, flow and certain simple species concentration profiles (7). In combination, these measurement tools allow for a detailed fundamental examination of the vaporization and transport mechanisms of coal mineral components in a coal conversion or combustion environment. 

Figure 14,2.1. Dendrogram obtained from the Euclidian distance of the first three principal components calculated from results of conventional coal analysis.

Twenty-eight patients that required coal tar treatment on an area larger than two-thirds of the body surface were studied (Cemikova et al. 1983). Tar paste (10 and 20%) was used for treatment in one application, approximately 1-6 g of coal tar containing 0.6% acridine was spread on the patient s skin. Urine analysis was performed by TLC to obtain information on polyaromatic and heterocyclic substances excreted in the urine. Further identification of the substance was performed by GC/mass spectrometry (GC/MS). The presence of acridine in urine after the coal tar application was identified by MS. The detection of acridine in urine provided proof of the absorption of a coal tar component through the skin. However, without additional information, no statements can be made regarding the dermal absorption of other coal tar components or whether acridine was preferentially absorbed through the skin. 

TG is chiefly used to determine content, as well as the temperature and course of decomposition. The selection of atmosphere (e.g., N2 for pyrolysis, air for oxidation) often allows the various components to be distinguished (e.g., coal analysis, material analysis). The decomposition temperatures generally differ and allow determination of the type and quantity of the components, e.g., hydrates, binders, carbonates, copolymers, etc. Isofliermal measurements can be used to determine adsorption/desorption isoflierms of materials in order to reveal the geometry of the surface and pore structure, the sorption capacity and the sorption kinetics, etc. 

Coal Analysis. Customary practice in reporting the components of a coal is to use proximate and ultimate analyses (see Glossary). 

This report presents a set of failure rate and time-to-restore data for typical components of a coal gasification combined cycle power generation unit. The data was used to examine the reliability and availability of a generic power generation unit using risk analysis models. 

The composition of coal is conveyed by representing its proximate and ultimate analysis. The former implies determination of contents of moisture, volatile matter, fixed carbon, and ash, while the latter implies total carbon, hydrogen, oxygen, nitrogen, sulfur and ash. Here, an account will be provided of the constituents of coal, moisture, volatile matter, ash, fixed carbon, and some miscellaneous components. 

Principal components analysis of the characteristics of the coals in each of the three groups showed that the interrelationships between coal properties were markedly different that is, the trends of properties with increasing rank are different, in... 

LC-MS has been used to study various aromatic fractions from coal derived liquids, and there are also a number of reports on its use in the analysis of porphyrin mixtures [601,602]. The early work by Dark et al. [601] using LC-MS for coal-derived liquids was mainly concerned with the separation and identification of polycyclic aromatic components. However, it is interesting to note that... 

Much of the literature published on minerals is based on high rank coals, but can be related to low rank coals (18). In general, the silicate minerals represent the major component of the minerals contained in coal. The most common analytical methods for mineral characterisation and analysis are listed in (19) and covered in detail in the "Analytical Methods for Coal and Coal Products" series (20). 

Fourier transform infrared (FTIR) spectroscopy of coal low-temperature ashes was applied to the determination of coal mineralogy and the prediction of ash properties during coal combustion. Analytical methods commonly applied to the mineralogy of coal are critically surveyed. Conventional least-squares analysis of spectra was used to determine coal mineralogy on the basis of forty-two reference mineral spectra. The method described showed several limitations. However, partial least-squares and principal component regression calibrations with the FTIR data permitted prediction of all eight ASTM ash fusion temperatures to within 50 to 78 F and four major elemental oxide concentrations to within 0.74 to 1.79 wt % of the ASTM ash (standard errors of prediction). Factor analysis based methods offer considerable potential in mineral-ogical and ash property applications. 

Haaland and coworkers (5) discussed other problems with classical least-squares (CLS) and its performance relative to partial least-squares (PLS) and factor analysis (in the form of principal component regression). One of the disadvantages of CLS is that interferences from overlapping spectra are not handled well, and all the components in a sample must be included for a good analysis. For a material such as coal LTA, this is a significant limitation. 

Experience in this laboratory has shown that even with careful attention to detail, determination of coal mineralogy by classical least-squares analysis of FTIR data may have several limitations. Factor analysis and related techniques have the potential to remove or lessen some of these limitations. Calibration models based on partial least-squares or principal component regression may allow prediction of useful properties or empirical behavior directly from FTIR spectra of low-temperature ashes. Wider application of these techniques to coal mineralogical studies is recommended. 

The hypothesis that coals can be considered to consist of two component phases has its origins in observations of coal behaviour as well as deriving from the analysis of coals and attempts to define their structure. The results of extensive studies of untreated, preheated and hydrogenated coals, using analytical and microscopic techniques, have allowed some insight into the association between the so-called mobile phase and macromolecular network, and have provided information upon differences in their chemical properties. 

In Curie-point Py-LVMS studies of maceral concentrates (22). vitrinitic moieties were shown to be the main source of the hydroxy aromatic components. Thus, the hydroxy aromatic signals observed in Figure 2d appear to be primarily derived from vitrinite-like components by means of pyrolytic processes. Presumably, therefore, the "nonmobile phase", rather than the "mobile phase , is the main source of the phenols observed in TG/MS and Py-MS studies of Pittsburgh 8 coal (9,16). Further support for this conjecture comes from the observation that phenolic products are also observed in Py-MS analysis of pyridine extracts of Pittsburgh 8 coal known to contain colloidal matter whereas the corresponding tetrahydrofuran extracts, free of colloidal material, produced no phenols (21). 

A Sulfur K Edge X-ray Absorption Near Edge Structure (XANES) Spectroscopy method has been developed for the direct determination and quantification of the forms of organically bound sulfur in nonvolatile petroleum and coal samples. XANES spectra were taken of a number of model compounds, mixtures of model compounds, heavy petroleum and coal samples. Analysis of the third derivatives of these spectra allowed approximate quantification of the sulfidic and thiophenic components of the model mixtures and of heavy petroleum and coal samples. These results are compared with those obtained by X-ray Photoelectron Spectroscopy (XPS). 

The flame ionization detector (FID) can be used for the detection and quantitative estimation of components separated by the GC. Identification of major species can be achieved by a mass spectrometer which can not be used for quantitative analysis of complex mixtures such as coal liquids. 

In both component and factor analysis, the properties of the system being observed are assumed to be linearly additive functions of the contribution from each of the m causalities that actually govern the system. For example, for airborne particles, the amount of particulate lead in the air could be considered to be a sum of contributions from several sources including automobiles, incinerators and coal-fired power plants, etc. 

Several of the minor components of coal are of importance, because of the quantity present on occasion, but more so in some cases by virtue of the special properties they possess which are undesirable when the coal is used for certain purposes. For example, to arrive at a correct figure for the combustible carbon in coal, it is necessary to apply a correction for the quantity of carbonate associated with the sample. Combustion analyses determine only the total carbon. Again, coking coals should have low phosphorus content, and anthracites used for malting should contain only very small quantities of arsenic, so that the determination of these elements becomes necessary in certain cases. Since both are found normally in small amounts, they are not included in the general statement of the ultimate analysis but are reported separately. 

Various separation methods have been used to isolate, fractionate, and characterize humic materials. Originally it was fractionation, based on solubility differences of humic components in diluted alkalis and acids, which laid the ground work for the first classifications of humic substances (HS) in the 19th century (Mulder, 1861 Sprengel, 1837) and provided for operational definition of HS (Kononova, 1966). And now, alkali extraction is the method of choice for isolating HS from solid humus-containing substrates like soil, peat, coal, and so on (Swift, 1996), while hydrophobic resins (e.g., Amberlite XAD resins) are typically used to extract HS dissolved in natural waters (Aiken, 1985). Initial research on HS began with the used simple separation methods to prove, examine, and define characteristics of components of humic matter (Oden, 1919).Today, however, advances in HS research require ever more sophisticated techniques of separation combined with structural analysis (Orlov, 1990 Stevenson, 1994). 

---