Variable coalification

Schopf JM (1948) Variable coalification The processes involved in coal formation. Econ Geol 43 207-225 Schopf JM (1956) A definition of coal. Econ Geol 51(6) 521-527... 

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 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. 

Dr. Berkowitz I must question the validity of Dr. Teichmiiller s rather definite conclusions about the relative roles of time, temperature, and pressure in the coalification process. From an examination of Ruhr coals, Dr. Teich-miiller said that only temperature plays a significant role. I suggest that conclusions drawn from data for coals in other areas (e.g., Alberta and Pennsylvania) would lead to the conclusion that pressure rather than temperature was the determining variable therefore, I doubt whether Dr. Teichmiiller s quite unqualified statements could have general validity. Indeed, from first principles one would deduce a rather complex and variable situation. Thermodynamically, one could perhaps rule out time as an important parameter since, unless one accepted the concept of a "tunnelling factor, time alone will not... 

Before the FTIR data were analyzed together with coalification parameters in a components analysis, it was first necessary to select which variables to use. In general, the number of variables should not exceed one-third of the number of samples (in this study the maximum number is 8). Components analyses were performed on data for the aliphatic stretching and aromatic out-of-plane bending regions of the infrared spectrum in order to eliminate those variables that did not provide new information. 

Components analyses were performed next on variables selected from FTIR analyses together with some parameters of coalification. A preliminary components analysis on these parameters revealed that calorific value and moisture content were completely interdependent, so calorific value will be used here to represent both. In Table VII aliphatic CH3 groups at 2956 cm-1 show complete dependency with calorific value on component 1. The aliphatic bands at 2923 and 2891 cm-1 aiSo would show similar results because they were found to vary dependently with the band at 2956 cnrl -jn... 

Three variables are independent of coalification expressed by calorific value. The peak intensity of the band at 785 cm-1 loads entirely on component 2 although its area is split on two components. The symmetric CH2 stretching mode at 2853 cm l in the aliphatic region loads on component 3 along with small amounts of three other bands. The 834 cm-1 band jS once again independent of the other variables and also of coalification. 

A third variable, time, also plays an important role in the coalification process and adds to the complexity of the overall scheme. 

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