Coal as-determined

Figure 1. Occurrence frequency of elements in 13 raw coals as determined by spark-source mass spectrometry. All quantities in %. ND = not determined. O = checked hut not detected.

Table IV. Mercury in Coal as Determined by Atomic Absorption...

Recently, Honda and Hirose (13), on the basis of Riley s experiments on coke, suggested that the available internal area of coal in a phosphoric acid-dichromate oxidation should be proportional to the internal area of the coal as determined by a vapor absorption. 

Menster et al. [8] used electrical pulse heating to apply a heating rate of nearly 10" °C/s to a number of coals. The total volatile yield from low-rank hVC and hVA coals displayed a maximum in the temperature region 700-800°C. The peak volatile yields exceeded the volatile matter contents of the coals as determined by the standard ASTM method. 

Table I. Electron-Nuclear Hyperfine Constants for Vitrains from Selected Coals as Determined by ENDOR Spectrometry...

Fig. 13. Variation of (CN)2/HCN yield ratio with temperature for Canadian coal, as determined for 30 min reaction period. Shaded points for reaction in the luminous discharge zone open points downstream from the luminous zone. Inset shows variation of cumulative 2-h yields and (CN)2/HCN yield ratio with rank of Canadian coal. (Redrawn from Nishida, S., Berkowitz, N. Fuel 52, 262 (1973), by permission of Dr. Berkowitz and the publishers, IPC Business Press Ltd.)...

Plastic properties of coal, as determined by the Gieseler plastometer, appear to be sensitive to oxidation, which can have a maiked effect in decreasing the maximum fluidity. In fact, prolonged oxidation may completely destroy the fluidity of a coal. To reduce oxidation, samples should be tested soon after collection or, if delay is unavoidable, storage under water or in a nonoxidizing atmosphere such as nitrogen is advisable. 

Carbon-13 magnetic resonance spectroscopy has found some use in determining the fraction of carbon atoms that are in aromatic locations (fj as well as in attempting to define the structure of the aromatic ring system, although the question of the aromatic nature of coal as determined by this method is certainly open to debate. And there is the possibility of serious under estimation of the aromatic nature of coal by this method (Snape et al., 1989). 

PPS fiber has excellent chemical resistance. Only strong oxidising agents cause degradation. As expected from inherent resia properties, PPS fiber is flame-resistant and has an autoignition temperature of 590°C as determined ia tests at the Textile Research Institute. PPS fiber is an excellent electrical iasulator it finds application ia hostile environments such as filter bags for filtration of flue gas from coal-fired furnaces, filter media for gas and liquid filtration, electrolysis membranes, protective clothing, and composites. 

Working co-operatively with others, we have found some indication that certain alilphatic linkages between aromatic nucleii are involved in the rapid dissolution of coal. The absolute aliphatic hydrogen content as determined by P. Solomon using FTIR (22) shows a very good linear relationship with conversion of coal in 3 minutes to pyridine soluble materials (Figure 14a). 

Experimental Procedure. Morwell brown coal was solubilised by reacting with phenol, in the presence of para toluene sulfonic acid, at 1830C, and the reaction product was then separated into four fractions and analysed according to procedures described elsewhere (lj. The structural characteristics of the four fractions as determined by the present work and confirmed by reference to the literature ( ,3) are summarised in Table I. As these characteristics are influenced to some extent by the presence of chemically combined phenol, the content of this in each fraction is also estimated. 

After reaction, any solid residue was filtered off and the liquid product was separated by distillation into a bottoms product and a distillate that included unreacted Tetralin and low-boiling products from both the coal and the Tetralin. As tetralin breaks down under dissolution conditions to form mainly the tetralin isomer 1-methyl indan, naphthalene and alkyl benzenes (4) it was assumed that no compound with a higher boiling point than naphthalene was formed from the solvent, and the distillation to recover solvent was therefore continued until naphthalene stopped subliming. Some residual naphthalene remained in the bottoms product its mass, as determined from nmr and elemental analysis, was subtracted from the mass of bottoms product recovered and included in the amount of distillate recovered. It was assumed that all naphthalene present came from the Tetralin, not the coal. However, as the amount of tetralin reacted was 10 times the amount of coal this assumption appears reasonable. 

Distribution of protons by type and overall aromatic/aliphatic proton ratios for the original fractions and bottoms products, as determined by proton nmr. Proton distribution for fraction D and the whole coal are not included as these materials were only partly soluble and the resultant spectra were not representative of the whole material. 

The first method chosen to express the coal-mineral association results is in terms of the weight fraction of mineral matter in the individual particles, as determined from their cross section. The resulting distribution is comparable to the so-called "grade distributions" used in the mineral industry [8,9]. Such a distribution is included in Table II for the Upper Freeport coal. The data in the table indicate that pyrite is preferentially liberated as compared to quartz or kaolinite. About 78% of the pyrite is in particles containing more than 80% mineral matter, which should be easily removed by density-based separations. 

Air oxidation of coal causes a significant decrease in the concentration of aliphatic bridges as determined by acid-catalyzed transalkylation of coal with phenol. Infrared analysis of the raw and oxidized coals indicate that the hydrocarbon bridges are converted to carbonyl groups. Plausible explanations have been offered for the formation of carbonyl groups from aliphatic bridges. 

The swirl number, a dimensionless ratio of the angular momentum to the product of the axial momentum and the radium of the burner, can be varied through separate control of the two secondary air streams in order to study various burner designs. The air flows were measured using sharp edged orifices. Control of the air flows and calibration of the coal feeder made it possible to duplicate combustion conditions as determined both by exhaust gas analysis (CO, CO2, O2, NO, NOx) and aerosol characteristics. 

Katrinak, K. A. Zygarlicke, C. J. 1995. Size-related variations in coal fly ash composition as determined using automated scanning electron microscopy. Fuel Processing Technology, 44, 71-79. 

Table I. Affinity of Elements for Pure Coal and Mineral Matter as Determined from Float—Sink Data...

For a trace element concentration to be certified by NBS, it must be determined by at least two independent methods, the results of which must agree within a small experimental error range of 1% to 10%, depending on the nature of the sample and the concentration level of the element. Such accuracy in determining some trace elements for certification of coal SRM is achieved most easily by NAA with radiochemical separation. Scientists at NBS have extensively tested a neutron activation method that involves a combustion separation procedure on coal as well as on several other matrices to be certified as standard reference materials. The procedures they have thus developed to determine mercury (12), selenium (13), and arsenic, zinc, and cadmium (14) are outlined in a following section on methods for determining specific elements in coal. 

Major, Minor, and Trace Element Composition of Coal and Fly Ash, as Determined by Instrumental Neutron Activation Analysis... 

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