Brown coal distribution

Figure 2. Distribution of the oxygen-containing functional groups in Rhenish brown coal.

In order to establish statistically usable data on the briquetting behaviour of Rhenish brown coals, the 15 brown coal lithotypes were briquetted under identical conditions (water content, grain size distribution and mould pressure) with a laboratory press. 

Victorian brown coal occurs in five major lithotypes distinguishable by color index and petrography. Advantage has been taken of a rare 100 m continuous core to compare and contrast chemical variations occurring as a function of lithotype classification. For many parameters there is a much greater contrast between the different lithotypes than there is across the depth profile of (nearly) identical lithotypes. Molecular parameters, such as the distributions of hydrocarbons, fatty acids, triterpenoids and pertrifluoroacetic acid oxidation products, together with gross structural parameters derived from IR and C-NMR spectroscopic data, Rock-Eval and elemental analyses and the yields of specific extractable fractions are compared. 

Grady W. C., Eble C. F., and Neuzil S. G. (1993) Brown coal maceral distributions in a modern domed tropical Indonesian peat and a comparison with maceral distributions in middle Pennsylvanian-age Appalachian bituminous coal beds. In Modem and Ancient Coal-forming Environments, Geological Society of America Special Paper 286, (eds. J. C. Cobb and C. B. Cecil). Geological society of America, Tulsa, OK, pp. 63 —82. 

Catty acids are widely distributed in nature and have been studied extensively in petroleum (1, 2) and sediments (1, 3, 4, 5), as well as in living organisms (6, 7, 8). Fatty acids are major components in most living organisms, and since they are geochemically quite stable (9), they are important components in most depositional environments. The presence of fatty acids in coals has been recorded (10, 11, 12), but there appears to be little published information available on their distribution, particularly in brown coals, except in montan wax deposits (13, 14). In contrast, the distribution of n-alkanes in coals has been widely studied, and the maxima of the distributions have been shown to range from C29... 

Acid groups such as triterpenoid acids, dicarboxylic acids, and hydroxy acids also are present in brown coal. Although this paper is restricted to the monofatty acid levels and distributions in brown coal lithotypes, these other acid types also have been observed to vary in level and distribution with lithotype and may, in fact, prove to be useful as indicators of the depositional environments. 

The large differences in the distributions of n-fatty acids between the black and brown coal samples examined have been attributed to the significantly different rank of these coals. 

Potter et al. (1988) used a continuous fluid-bed dryer for drying Victoria brown coal. The fluidized bed (FB) dryer was 0.3 X 0.3 X 3 m (high) with four bubble caps to distribute steam. The disengaging region was 2.5 m. Both horizontal and vertical tube bundles were tried. 

Hard coals (high-rank bituminous coals) are the preferred precursor in many countries, because they can be used both for production of inexpensive activated carbons, and also for the more expensive granular, hard carbons with well-developed porous structures. As-received coals have some porosity (which decreases with increasing rank of coal), and consequently further treatments are needed to increase the porosity. Low rank coals (peat, lignite, brown coal), which do not fuse on carbonization, are used to produce activated carbons with a wide pore-size distribution. The yield of activated carbons from coal is generally larger than for lignocellulosic materials, above 30 wt%. 

Magnetic resonance spectroscopy has a considerable history of being applied to the issue of coal structure. However, as a historical beginning, the structural types in coal were first determined by means of statistical structural analysis (Francis, 1961). One of the first methods to supersede the statistical methods was based on proton (XH) magnetic resonance, which provided a quantitative distribution of the hydrogen types in coal (Brown and Ladner, 1960 Bartle, 1988 Maciel et al., 1993). 

Another form of heroin commonly distributed in the western and southwestern regions of the United States is called Black Tar or Mexican Brown. These varieties are produced in Mexico and—because they re manufactured crudely—have an either hard black coal or sticky, tar-like consistency. Purity rates range from 20-80%. 

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