Lithotypes

Coal lithotypes represent the macrostructure of coal and are, in fact, descriptive of the coal. A piece of coal will usually exhibit a definite banded appearance due to the accumulation of different types of plant debris during the formation of the organic sediment (White, 1911 Thiessen, 1931 Muller et al., 1990  

Smith and Smoot, 1990). This may be due to not only the deposition of a variety of different organic compounds that are believed to be the precursors of coal (Chapter 3) but also the accumulation of different parts of the plant (as well as different plants, e.g., trees, ferns, mosses, etc.) during the formation of the sediment (Murchison, 1991 Puttmann et al., 1991). Each compound type, tissue type, or plant type then progresses through the various maturation stages that eventually lead to coal. 

Obviously, this system of nomenclature of the macrostructure of coal does not take into account the rank of the coal or any potential differences in chemical properties that may exist between the various coal types since the basis of such macroscopic names is the origin of the material. 

Vitrain occurs as well-defined narrow bands which are seldom greater than 0.5 in. (1.0 cm) thick. The single band does not exhibit any fine layering but is coherent, uniform, brilliant, and glossy (in fact, vitreons) in its textnre. 

Humic matter (anthraxylon-like shreds 14 gm thick) Brown matter Spores, pollen, cuticles Resinous bodies Algal remains Opaque 

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There are certainly lithotypes that can be handpicked from European and American coals that are relatively rich in fusinite and semifusinite. However, it is perhaps significant that the mean content of total fusinite + semifusinite in 697 coal samples in the Penn State/DOE Data Base is 8.9%. On the other hand, the content of inertinite macerals in the Permian coals of Gondwana-land is notoriously high and much of this inertinite material consists of semifusinite (5,26,33,34), the concentration of which can be as high as 50% in the whole seam. 

As stated before, volatile carbon % is considered to be one of the most important parameters of hydroliquefaction. Also a fairly good linear relationship between the volatile carbon % in coal and low temperature tar yield from coal is found in Morwell brown coals, based on the data from the State Electricity Commission of Victoria (SECV) in Australia, as shown in Fig.9 Therefore, the low temperature tar yield is also estimated to be an important parameter. In addition, the color tone of brown coal (lithotypes) is shown in this figure. From this figure, it is observed that both volatile carbon % and low temperature tar yield are in a fairly good relation to the color tone of brown coal. Thus, as proposed by the Australian researchers, the color tone of brown coal is considered to be an important parameter. 

The chief microlithotypes noticed in the coals of Chirmiri are duroclarite and clarodurite. Duroclarite is dominant in zones 1-7 of Seam 4, while the microlithotype clarodurite is dominant in zones 8-25. Seam 2 is characterized by the microlithotype vitrinertinite V. This lithotype is predominant in the top and middle portion of the seam, while in the bottom portion duroclarite is predominant. 

Interspersed between the above dominant lithotypes, fusite is common. A gradual transition from clarodurite to fusite is common in most cases. 

In on effort to establish the mechanism of coal flotation and thus establish the basis for an anthracite lithotype separation, some physical and chemical parameters for anthracite lithotype differentiation were determined. The electrokinetic properties were determined by streaming potential methods. Results indicated a difference in the characteristics of the lithotypes. Other physical and chemical analyses of the lithotypes were mode to establish parameters for further differentiation. Electron-microprobe x-ray, x-ray diffraction, x-ray fluorescent, infrared, and density analyses were made. Chemical analyses included proximate, ultimate, and sulfur measurements. The classification system used was a modification of the Stopes system for classifying lithotypes for humic coals. 

Coal seams display two different modes of variation rank and type. The rank of the material under consideration is anthracite. Regarding type, coal is composed of different bands of materials, distinctly contrasted in regard to physical and chemical composition. These bands are termed lithotypes in this paper, after the word coined by Seyler (2) in 1954. 

The lithotype clarain, admittedly present, was not used in this study. Clarain is by definition a heterogeneous material composed of vitrain and durain bands, of less than an arbitrarily chosen thickness, generally 3-5 mm. For the purpose of this study, it was felt that this material could be described adequately if the vitrain and durain constituents were described. 

The following standard visual parameters were used to identify the lithotypes. 

All of the anthracites used in this investigation were from Pennsylvania except two, a Russian anthracite and a Welsh anthracite. Tables I and II indicate the various designations and sources of the anthracite and lithotype samples. 

Other physical and chemical analyses of the lithotypes were made to establish parameters for further differentiation. 

Table III. Isoelectric Points of Anthracites and Lithotypes Investigated...

Table IV. Distribution of Lithotypes in Anthracite Coal Samples...

Using polished pellets 1 inch in diameter, a microscopic particle classification analysis for lithotypes, developed for this research by the authors (I), was made of the various coals. Only vitrain, durain, and fusain were counted. Results are presented in Table IV. Standard visual parameters were used for particle identification. An analysis of this type, although not necessarily conclusive, is important for a relative comparison. Results of a check between... 

The apparent specific gravity of the various lithotypes was measured. Results (Table VI) indicate that the order of increasing density for the lithotypes is vitrain, durain, and fusain. For Pennsylvania anthracites, the specific gravity for vitrain was found to vary between 1.36 and 1.53 for durain between 1.43 and 1.73 for fusain between 1.93 and 2.30. 

Proximate and ultimate analyses results (Tables VII and VIII, respectively) show that fixed and total carbon content of the lithotypes decrease in the order vitrain, durain, and fusain. The reverse of this trend is found for percent ash content, vitrain having the least and the durains and fusains having the most. Durain was found to have the highest percentage of volatile matter vitrains have the highest percentage of sulfur. 

Table VIII. Ultimate Analysis of Anthracites and Lithotypes ...

Using procedures similar to Kinney (3) the infrared spectra were investigated. Results illustrated in Figure 3 indicate that the adsorption bands present in lower rank coals have disappeared, not only for the whole coal as reported by Kinney, but also for the various lithotypes. 

An iron content in some of the lithotype ashes was indicated by their brownish-red to dark earth brown colors. An x-ray fluorescence analysis (Table X) of the ash substantiated the presupposed presence of iron. Iron was generally found in all of the lithotypes. Detectable amounts of calcium were found in all the vitrains. 

An electronmicroprobe x-ray analyzer was used to determine how and what type of mineral matter is distributed on the surface of the various lithotypes. Results indicated that the mineral matter located at the surface is vastly different among the various lithotypes. The mineral matter appearing on the flat, homogeneous vitrain surface (Figure 4) was found to be distributed... 

From the foregoing it is evident that the lithotypes of anthracite are different. Differences in adsorption characteristics, surface structure, physical properties, and chemical composition conclusively demonstrate that the anthracite lithotypes are unalike and are distinct entities. It is also evident that to interpret research results of anthracite coals correctly, a petrographic knowledge of the coal is necessary. Anthracite cannot be regarded as a homogeneous substance. 

John A. L. Campbell A set of 11 anthracites was investigated. Table IV lists the distribution of lithotypes in these anthracite samples. The anthracites were found generally to contain 60-80% vitrain, 10-30% durain and 1-10% fusain. 

It is felt that any anthracite seam will readily yield such lithotypes. Because fusain is relatively soft and friable and is likely to be ground to fines during handling, it may appear only as coatings or fine bands in other coal types. The durain in many cases looks like slate. Not realizing these two factors one could, without close inspection, be easily misled into believing that the major lithotype, vitrain, is the only lithotype present in a particular seam. 

Mr. Campbell Anthracite lithotypes were investigated for their electro-kinetic characteristics to establish a basis for separation, utilizing froth flotation methods. The electrokinetic characteristics of macerals were not investigated. However, results from the lithotype work does imply that macerals have different electrokinetic characteristics. I believe electrophoretic methods could be used effectively to separate macerals for laboratory purposes. 

Mr. Campbell Elements present in the lithotypes were determined by ultimate analysis, emission spectroscopy, and x-ray fluorescence analysis. The presence of certain minerals was inferred from the determined elements. A direct mineralogical analysis was not undertaken. 

Figure 3 shows the compositions of the size fractions in terms of the micro-lithotypes just described. The fractions of the top sample differ from those of... 

Refs l)E.L.Tague, Casein, Its Preparation, Chemistry and Technical Utilization , Van Nostrand, NY(1926) 2)UUmann 3(1929), 110-15 (not found in new edition) 3)Thorpe 2(1938), 411-17 4)H.Hadert, "Casein and Its Uses , Translated from the Ger, ChemPubgCo, NY(1938) 5)E. Sutermeister F.L.Browne, Casein and Its Industrial Application , ACS Monograph No 30, Reinhold, NY(1939) 6)Kirk Othmer 3(1949), 225 36 7)M.Beau, "LaCasdine , Dunod, Paris (1952) 8)J.R.Spellacy, "Casein, Dried and t Condensed Whey , Lithotype Process Co, San Francisco, Calif(1953) 9)US Military Specification, MIL-C-11532... 

Clarain macroscopic coal constituent (lithotype) known as bright-banded coal, composed of alternating bands of vitrain and durain. 

Lithotypes constituents of banded coal vitrain, fusain, clarain, durain, or attrital coal, or a specific mixture of two or more of these. 

Drying removal of water from coal by thermal drying, screening, or centrifuging. Dull coal coal that absorbs rather than reflects light, containing mostly durain and fusain lithotypes. 

Fusain black macroscopic coal constituent (lithotype) that resembles wood charcoal extremely soft and friable. Also, U.S. Bureau of Mines term for mineral charcoal seen by transmitted light microscopy. See also Coal. 

Vitrain macroscopic coal constituent (lithotype) that appear as brilliant black bands of uniform appearance. See also Coal. 

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