Coal studies

Electron spin resonance (esr) (6,44) has had more limited use in coal studies. A rough estimate of the free-radical concentration or unsatisfied chemical bonds in the coal stmcture has been obtained as a function of coal rank and heat treatment. For example, the concentration increases from 2 X 10 radicals/g at 80 wt % carbon to a sharp peak of about 50 x 10 radicals/g at 95 wt % carbon content and drops almost to zero at 97 wt % carbon. The concentration of these radicals is less than that of the common functional groups such as hydroxyl. However, radical existence seems to be intrinsic to the coal molecule and may affect the reactivity of the coal as well as its absorption of ultraviolet radiation. Measurements from room... 

Thus the corrected volatile matter yield and the atomic H/C ratio both appear to be good parameters for assessing the reactivity of the coals studied. 

There is also intercorrelation between the volatile matter and the H/C atomic ratio for the South African coals studied. 

For the South African bituminous coals studied here the following conclusions can be made ... 

Victorian brown coals (Yallourn, Morwell) used here and their data on coal characteristics were offered by the Herman Research Laboratory of the State Electricity Commission of Victoria, to whom the authors wish to express their appreciation. In addition, they wish to thank Nissho-Iwai Co. Ltd. who kindly acted as intermediary with respect to Victorian brown coals studied. 

In this Laboratory, several potential liquid-phase treating agents have been studied at 225-275°C—that is, at temperatures well below 325°C, which appears to be the initiation temperature for pyrolysis of the coals studied here. Working with Wyodak coal in a ZnC -water melt at 250°C, Holten and coworkers (2,3) discovered that addition of tetralin increased the pyridine solubility of product to 75%, compared to 25% without tetralin. About 10 wt-% of water is required in the melt, because pure ZnC melts at 317°C. 

The coal studied, 78% C and 15.8% 0 daf, is derived from Carboniferous deposits from the Ziemowit mine in Poland. Its petrographic composition /% vol. dmmf/ is vitrinite, 60 exinite, 12 and inertinite, 28. 

Under the same py.-f.i.m.s. experimental conditions, compounds with normal and branched alkyl chains up to C32 were easily detected in natural waxes (15). Thus, the present results indicate that long alkyl compounds are not major constituents of the coal and discussing the FID signals of coal in terms of its "polyethylene structures" (B. C. Gerstein in reference 8) is not correct for the coal studied and may be not correct for other coals. 

The authors are indebted to Dr. Peter Given, to whose remembrance this paper is dedicated, for his invaluable encouragement, advice and fnendship in the early phases of the coal studies leading to the experiments reported in this paper. 

The extent to which these Flory interaction parameters apply to the pyridine-insoluble portion of the Illinois No. 6 coal is open to question. We cannot address this aspect fully here, but we have noted that the pyridine-soluble and -insoluble portions of the Illinois No. 6 coal studied here have similar carbon, hydrogen and oxygen contents. Maciel has observed that the aromaticities of the two portions of an Illinois No. 6 coal are similar as well.(12) Based on this alone, it seems that the pyridine-soluble portion is representative of the larger, crosslinked portion, at least for the Illinois No. 6 coal, but this aspect remains controversial,(12) so caution is warranted. 

In the present work, a mild thermal hydrogenation treatment was used to revive the coking properties of an oxidized bituminous coal. The coal studied was a severely weathered high volatile bituminous coal from eastern Canada. 

The final washability curve and histogram (Figure 5) are of arsenic in a sample from the Herrin (No. 6) Coal Member. The washability curve shows an intense concentration of arsenic in the heavier fractions. The curve approaches the abscissa and if extrapolated would intersect the ordinate near the origin. Arsenic is one of the least organically related elements in all four of the coals studied. 

Only one NAA determination was made on each of the 10 coals studied by O Gorman et al. No estimate of the method s precision or sensitivity is given. Combustion-double gold amalgamation-atomic absorption results agreed well with the neutron activation results, and the former method was therefore considered to be more reliable than a combustion-solution-atomic absorption method that gave lower results. 

Solids Sampling and Analysis. The coal consumption data is compiled in Table II. The ash, BTU, and sulfur analyses on the coal consumed during the 1-wk test period is presented in Table III. The data from the mercury in coal determinations are given in Table IV. Based on the authors experience with mercury in coal studies, the resulting concentrations are average for eastern United States coals. The author has found the spread in the individual coal determinations to be common when analyzing 0.5-g samples. The data in Tables III and IV show a relation-... 

In 1961 a number of coal research workers felt that a conference in the U. S. devoted to fundamental coal studies from many different viewpoints would be useful for those resident in the North American continent. The committee below organized such a conference. 

Under the optical microscope the texture of products derived from the three coals studied show an anisotropy of the type which already has been described for similar materials (I, 4, 9). The texture of the l.t. pitch coke is entirely isotropic, whereas the h.t. pitch coke is characterized by a pronounced anisotropy in bands. The anisotropy of the carbonization products of mixtures of l.t. and h.t. pitches varies linearly as a function of the composition of the mixture (8). 

Table III presents the reaction rate and the induction time for reaction (as defined in Figure 2) for the five coals studied. These data were taken under the following conditions 109.5°C., 1 N sodium hydroxide, and 8.5 atm. of oxygen partial pressure. The mesh size of the coals was through 60 mesh on 100 mesh. The reaction rates are based on the external area of the coal particles.

For the coal studied here, a bituminous Western Kentucky 9/14 coal, dissolution of the coal has been shown to occur very rapidly, requiring less than 30 minutes to liquefy most of the coal ( 90 percent). However, a relatively long reaction time (120 min.) is required to reduce its sulfur level low enough to meet even the current standards (1). A new short residence time two-stage SRC type process has been suggested by Auburn University (2 ) for solvent refining this coal. This process has been shown to have the potential of producing a low-sulfur solid SRC product that meets the proposed NSPS. It involves the dissolution of the coal... 

The proposed NSPS can be met by hydrotreating the coal liquids obtained by filtering the product from the coal dissolution stage. The desulfurization kinetics can be presented by two parallel first-order rate expression, and hydrogen consumption kinetics can be presented by a first-order rate expression. A linear relationship exists between total sulfur content and SRC sulfur content of the hydrotreated product. For the Western Kentucky bituminous 9/14 coal studied here, the maximum selectivity and lowest SRC conversion to oil for a fixed SRC sulfur content are obtained using the highest reaction temperature (435°C) and the shortest reaction time 7 min.). ... 

The preliminary results of studies now underway suggest that the spectral peak (A max) of some macerals, is more sensitive to variation in coal rank than previously believed. In the high volatile bituminous coals studied, an increase of 3 V-types (0.45 -0.75% reflectance) resulted in about a 50 nm increase of A max. 

The aqueous Na2C0, and molten NaOH/KOH treatments, followed by acid washes, effectively removed many trace elements from the coals studied. 

C. F. Braun presented a fine reference paper (9) on gasification plant sizing using one process from their Western sub-bituminous coal study of processes as an example. A table was presented, dated Sept. 1978, which presented average 20-year gas costs in January 1976 dollars. C. F. Braun presented another... 

The chapters in this symposium volume represent a cross-section of current research on coal. The title of the symposium reflects the application of the aforementioned techniques to coal studies, the contents of the chapters underscore how rapidly technology is transferred from one discipline to another, and the authorship reveals the universality of interest in coal studies, including as it does, contributors from government, industrial, and, especially, academic laboratories. 

The effect of mineral matter present In subbituminous coals was Investigated by carrying out non-catalytlc liquefaction with hydrogen and synthesis gas. Most of the twelve coals studied could be readily liquefied to a low viscosity and low sulfur oil In the absence of added catalysts with synthesis gas at temperatures of 400-450°C and operating pressures of 3800-4400 psl. Comparison with coal liquefaction using pure hydrogen at optimum liquefaction temperature of 425°C and pressure of 3800-4000 psl resulted In lower conversions, lower selectivity to oil and a product with higher viscosity. 

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