Coal formation

The Phocene lignites in Alaska, southeastern Europe, and southern Nigeria are the youngest coals. A number of peat accumulations in different parts of the world representing a range of climates indicate that the process of coal formation continues to take place. 

According to the autochthonous, in situ theory of coal formation, peat beds and subsequently coal were formed from the accumulation of plants and plant debris in place. According to the allochthonous theory, the coal-producing peat bogs or swamps were formed from plant debris that had been transported, usually by streams or coastal currents, to the observed burial sites. 

Perlman, W. "Fracturing Coal Formations," Chemical Abstracts. 103(24) 198382n(1985). 

It is well known that the characteristics of coal differ widely according to the age of the coal formation as well as to the location of coal, etc. And the reactivity during hydroliquefaction depends on the characteristics of coals. This relationship will he a guidance to select and develop coal mines. Many parameters to indicate the reactivity of coal have heen proposed (l, 2, 2). Among these parameters, carhon content, volatile matter content, value of H/C atomic ratio, reactive macerals content, etc. are reported to he relatively closely related parameters to coal reactivity. However, these relations are usually found only in limited reaction conditions. Therefore, attempts to find better parameters still continue. 

The object of the present study was to measure the ratios of organic carbon, nitrogen, and hydrogen in the detritus sinking in lake water and in the sediments and to discuss the decomposition processes of these components in order to gain basic knowledge concerning the mechanism of coal formation. 

Such attack can always be detected afterwards by a mottled or pitted appearance of the cell walls. Also, I do not think that Myxomycetes, the slime molds, were important primary agents in the biochemical stages of coal formation because their preferred habitat is, for example, rotting tree stumps rather than a peaty mass. 

Irving A. Breger There is little doubt that nitrogen was introduced at a very early stage of coal formation. 

Bhupendra K. Mazumdar. It is difficult for us to accept the view that temperatures of the order of 600°C. or so must have been involved in forming fusinites. One would have to imagine the raging of forest fires during primordial times in all areas of coal formation and right in peat bogs. 

Coal Formation in the United States. It is postulated that coal formed in the U.S. during three major geological periods. 

A system of joint planes is often observed in coal formations, and these joint planes (cleats) are usually perpendicular to the bedding planes. Thus, cleat joints are usually vertical. The main system of joints is more commonly called the face cleat, whereas a cross-system of jointing is called the butt cleat. Furthermore, the cleat system in coal has a pronounced effect on the properties of a coal deposit. For example, holes drilled into coal perpendicular to the face cleat are said to yield from 2.5 to 10 times the amount of methane gas from the formation as holes drilled perpendicular to the butt cleat. Also, the cleat system of fracture and the frequency of cleats may determine the size of run-of-mine coal. In general, a pair of cleats will be oriented at about 90° to each other, and the orientation of the cutting elements influences the output of coal-mining machines (Figure 8.4). 

The concept behind the word "macerals" is that the complex of biological units represented by a forest tree which crashed into a watery swamp and there partly decomposed and was macerated in the process of coal formation, did not in that process become uniform throughout but still retains delimited regions optically differing under the... 

High sulfur content in coal hinders the use of coal resources because sulfur dioxide emissions from utility and industrial boilers are a cause of acid rain. Thus, research into the nature of sulfur in coal is important for improving coal utilization. Geochemical studies of sulfur in coal provide information about the abundance, distribution, and speciation of sulfur in coal. Many of these properties are determined by geological environments and processes of coal formation. 

Yurovskii (48) recognized the importance of elemental sulfur in the formation of pyritic and organic sulfur compounds and suggested that the elemental sulfur found in coal today is a primary substance formed during coal formation. However, this view is unsupported by recent data (47). 

Sulfur isotopic measurements can shed light on the origin of sulfur in coal. The 34S/32S ratio depends on the source of sulfur and the geologic processes involved during coal formation. For example, isotopic compositions are different for the two principal sources of sulfur in coal 1) the sulfur preserved from the precursor plant material, and 2) the sulfur derived from the bacterial reduction of dissolved sulfate in ambient waters. Plant assimilation of sulfur results in a slight depletion of 34S (4-4.5%c) relative to the 834S in the dissolved sulfate source (102.103). In contrast, the dissimilatory bacterial reduction of sulfate results in a large isotopic fractionation sulfide sulfur can be depleted as much as 60%o in the heavy isotope (89.104-106). 

Low-sulfur coal in the western U.S. has a low molybdenum content with an average of 2.1 ppm (118). compared to an average of 10.7 ppm in the Illinois Basin (97). Thus, the molybdenum content appears to be indicative of a sedimentary environment during coal formation. 

Solid solutions in metallic alloys are normally compositionally very uniform random variations of 5% would be unusual. Also, a two phase layer normally is found between two solid solutions. The sulfur distribution in coal seems not to behave this way. Apparently, the distribution pattern established at some early stage of coal formation is frozen-in and the organic sulfur is bound so tightly to its hydrocarbon sites that it cannot diffuse until the temperature of the coal is raised to 400°C or above (18). 

Bergius F. Articles on the theory of coal formation. Naturwissenschaften. 1928 16 1-10. 

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