Coalification

Solvent extraction using nonreactive Hquids, such as C - or C -alcohols, benzene, or benzene-alcohol mixtures, yields generally 5—20% wax or bitumen (15). The yield and composition of the product are determined primarily by the petrologic character of the coal, not its degree of coalification. Montan wax is extracted from suitable coals for a variety of purposes. 

Geochemical Stage. The conversion of peat to bituminous coal is the result of the cumulative effects of temperature and pressure over a long time. The sediment covering the peat provides the pressure and insulation so that the earth s internal heat can be appUed to the conversion. The temperature increase is about 4 to 8°C for each 100 m of depth. The changes in plant matter are termed normal coalification. 

Moisture is lost and the chemical composition changes during coalification. Oxygen and hydrogen decrease and carbon increases. These compositional changes are accompanied by decreases in volatile matter and increases in calorific value. The volatile matter and calorific content are the main criteria used for commercial classification in the United States and for the International Classification. 

Natural gas (or raw gas) is gas as produced from a reservoir. It is a mixture of gaseous hydrocarbons and may also contain varying amounts of other gases (N2, CO2, H2S, He, Ar, etc.). In many places natural gas is associated with the formation of oil, in other places it is related to the coalification of organic material. 

Further Aspects of the Effects of the Environments of Deposition and Coalification... 

The behavior of macrinite and micrinite in industrial processes is not clearly understood. As stated above, many U.S. petro-graphers treat both of these constituents as MinertM coal constituents. On the other hand, overseas workers have observed that micrinite may not be inert during carbonization. Because some micrinite appears to have been generated during the progressive coalification of the liptinite macerals, it might, instead, be quite reactive. 

These reactions proceed smoothly in the presence of hydrogen donating aromatic solvent (1-4) at temperatures from 400°C to 450°C, resulting in the formation of so called solvent refined coal with carbon content of 86-88% on maf basis independent of coalification grade of feed coal. 

Grotek, I. 2005. Variability of coalification degree of the dispersed organic matter in the Carboniferous deposits along the margin of the East European Platform. Polish Geological Institute Bulletin, 413, 5-80. 

The phenol, the cresol isomers, and the dimethylphenols, major pyrolysis products in e Moscow wood sample, are probably also derived frt>m lignin precursors that have been altered through coalification reactions. Hatcher [fr] have shown that an increase is observed in the relative proportion of phenols and cresols as rank of coaHfred wood samples increases to subbituminous coal. Comparing the distribution of pyrolysis products from the Moscow wood to that of other coalified wood samples of Hatcher allows us to deduce that the... 

The analysis of lignitic woods by analytical pyrolysis has shown that lignin structural units can be preserved as biomaikers in samples as old as Carboniferous age, or approximately 300 million years. At least half or more of the pyrolysis products in lignitic wood of Cretaceous age are methoxyphenols characteristic of lignin. The pn uct distributions in these Cretaceous samples indicate that the lignin is mainly altered in the 3-carbon side chains. Phenols, cresols, catechols, and other methylated phenols account for most of the remaining pyrolysis products. It is likely diat these products are also derived frx>m li in, especially lignin that has been altered by coalification reactions. 

The high-volatile Liddell bituminous coal (Figure 2 (E)) shows little indication of thermally-activated molecular mobility below 500 K. There is some fusion between 500 and 600 K followed by a major fusion transition above 600 K which appears very similar to the high temperature transition of the Amberley coal. This Liddell coal, however, has only 6% liptinite, has a crucible swelling number of 6.5 and exhibits considerable Gieseler fluidity. We therefore attribute this high temperature fusion event to the aromatic-rich macerals of the coal and associate it with the thermoplastic phenomenon. This implies that a stage has been reached in the coalification processes at which aromatic-rich material becomes fusible. 

The primary component of coal is carbonaceous material resulting from the accumulation and decay of plant matter in marine or freshwater environments and marshes (Hessley et al. 1986). As plant matter accumulates it becomes humified and may eventually be consolidated into coal through a process called coalification. In the organic matrix, C is the major element by weight, with smaller amounts of H, O, N, and S, and many trace elements. The abundance of these trace elements is highly variable, but based on the reported trends in the affinity of elements for the organic fraction of coal (Table 1), elements such as B, Ge, Be, Ti, and V are expected to exist primarily within the organics in coal. 

Coal contains detrital minerals that were deposited along with the plant material, and authigenic minerals that were formed during coalification. The abundance of mineral matter in coal varies considerably with its source, and is reported to range between 9.05 and 32.26 wt% (Valkovic 1983). Minerals found in coal include (Table 2) aluminosilicates, mainly clay minerals carbonates, such as, calcite, ankerite, siderite, and dolomite sulphides, mainly pyrite (FeS2) chlorides and silicates, principally quartz. Trace elements in coal are commonly associated with one or more of these minerals (see Table 2). 

For further consideration some additional remarks must be made. In coalification not only might lignin alteration itself play an important role, but... 

The polymers formed contain an increasing proportion of aromatic structure with increasing degradation of the side chain. (This fact is interesting for the problem of coalification.)... 

Coalification occurs under conditions which are more anaerobic than those used in the laboratory work and are less favorable for microorganisms. The oxygen tension is lower and decreases with time. More and more oxygen-containing compounds must serve as oxidizing agents. Temperature and pressure increase, and time begins to play an important role. 

---