Brown coal structure

R. A. Durie, ed.. The Science of Victorian Brown Coal Structure, Properties and Consequencesfor Utilisation, Butterworth Heinemann, Oxford, 1991. An excellent reference not only for Victorim Brown Coal, but for lignitic coals of the world. 

Figure 1. Schematic composition of the brown coal structure.

The Effect of Coal Structure on the Dissolution of Brown Coal in Tetralin... 

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. 

The action of organic solvents on natural polymers combustible minerals (coal and brown coal or peat) is intensively studied for a long time due to following reasons. Firstly, this is one of the successful method of studying the structure of combustible materials and the second is their technological application for obtaining of a so-called montan-wax or low-molecular liquid extracts which can be transformed into synthetic liquid fuel due to hydration process. Moreover, an interaction of a coal with the solvents is a basis of the coals liquation processes and coals transformation into liquid fuel. 

One means of Investigating molecular structures Is to determine the extent to which a solid can be destabilized by heat before It decomposes. Significant molecular mobility activated In brown coals at temperatures between 300 and 600 K has been related to the fusion of the extractable, allphatlc-rlch fraction of the coals ( ). 

Fusion of the llptlnlte macerals In bituminous coals commences at lower temperatures and reaches a much greater extent than that of the aromatic macerals (Figures 4 and 5). The greater thermal stability Indicated by the much higher fusion temperatures of the bituminous llptlnltes compared to brown coal llptlnltes can be explained In terms of these materials having a more highly crossllnked macromolecular structure than the llptlnltes In the brown coals. This Increase with coallflcatlon could be the consequence of In situ crosslinking of material or the selective loss of llptlnlte fractions that are less crossllnked and therefore less Inherently stable ... 

Yamashito, H. Yoshida, S. Tomita, A. (1991) Local structures of metals dispersed on coal. 2. Ultrafine FeOOH as active iron species for steam dassification of brown coal. Energy Euels 5 52—57... 

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). 

Lignite brownish-black woody-structured coal, lower in fixed carbon and higher in volatile matter and oxygen than either anthracite or bituminous coal similar to the brown coal of Europe and Australia. See also Rank. 

Correlations Between Petrographical Properties, Chemical Structure, and Technological Behavior of Rhenish Brown Coal... 

Only a model can establish the complex, heterogeneous structure of brown coal. 

CORRELATIONS BETWEEN PETROGRAPHICAL STRUCTURE, CHEMICAL COMPOSITION AND REFINING BEHAVIOUR OF RHENISH BROWN COAL... 

Victorian brown coals are thought to be largely amorphous, containing aromatic layers of single substituted benzene rings crosslinked by aliphatic chains to form a three dimensional structure. Their carbon content is quite low, varying from 60 to 70. One would therefore expect its porous system to be somewhat like that of an open structure having micropores which are randomly-oriented. In this preliminary study two samples of Yallourn ream coal were taken from the Yallourn open cut mine in the Latrobe Valley, Victoria, Australia. The samples, a pale and a medium dark lithotype, are representative of the extremes in coal types found in the Yallourn ream. 

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. 

The lithotype profile was investigated in greater detail with the product composition of the different brown coals being reported in Tables 1 and 2. A distinct decrease in the total concentration of detectable oxidation products occurs with darker lithotypes (Table 1). This result is consistent with increasing aromaticity (Figure 2) and the preferential attack on aromatic structures by the pertrifluoroacetic acid reagent. The total destruction of the tertiary structure within the brown coal lithotypes is evidenced by their low yield of insoluble products (Residue) which is primarily composed of mineral matter. 

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