Fusinite macerals

Fusinite macerals are generally held to be inert in coking, and in liquefaction, as will be seen below. In the production of metallurgical coke, they do not become fluid on heating, and... 

Fusinite maceral distinguished by the well-preserved original form of plant cell wall structure, intact or broken, with open or mineral-filled cell lumens (cavities). 

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. 

For American and European coking coals the behaviour of semi-fusinite is generally less important since only small quantities of this maceral are usually present. However, South African coal used in coke oven-blends contains as little as 40 per cent vitrinite and as much as 45 per cent reactive semi-fusinite (12). The partial reactivity of the semi-fusinite fraction during liquefaction of Australian coals has been reported by Guyot et al (13). They found that the low reflecting inertinite in two coals up to (a reflectance from 1.40 to 1.49) was reactive. This agrees with the results of Smith and Steyn (12) who consider that the semi-fusinite fraction in South African coals up to V- 5 (1.50 - 1.59) can be reactive to coking. 

It is possible to produce some liquid hydrocarbons from most coals during conversion (pyrolysis and hydrogenation/ catalytic and via solvent refining)/ but the yield and hydrogen consumption required to achieve this yield can vary widely from coal to coal. The weight of data in the literature indicate that the liquid hydrocarbons are derived from the so-called reactive maceralS/ i.e. the vitrinites and exinites present (7 8 1 9). Thusf for coals of the same rank the yield of liquids during conversion would be expected to vary with the vitrinite plus exinite contents. This leads to the general question of effect of rank on the response of a vitrinite and on the yield of liquid products and/ in the context of Australian bituminous coals, where semi-fusinite is usually abundant/ of the role of this maceral in conversion. 

Liptinites were made up of hydrogen-rich hydrocarbons derived from spores, pollens, cuticles, and resins in the original plant material. Vitrinites were made up of wood, bark, and roots and contained less hydrogen than the liptinites. Inertinites are mainly oxidation products of the other macerals and are consequently richer in carbon. The inertinite group includes fusinite, most of which is fossil charcoal, derived from ancient peat fires. 

The above models are representative of the active macerals, particularly vitrinite. Inert macerals, such as fusinite and micrinite, are believed to have large aromatic planar structures with fewer substituents (14) and behave similar to chars. 

Semifusinite is also included in the vitrinoid group of macerals. It is distinguished from fusinite by a degree of translucence in thin section and lower reflectivity in polished specimens. Semifusinites may be subgrouped according to appearance, which however was not attempted. The semifusinites very often occur as a transition stage between vitrinoids and fusinoids. 

Fusinite with small cells which show a sharp contact with the adjoining maceral and the cells are more or less granular in appearance. 

Fusinite with large cells which are not sharply defined from the adjoining macerals and the cells are irregular in appearance. 

Samples Studied. From British Seams. The suite of samples was collected and separated by the Coal Survey of the National Coal Board under the direction of Dr. G. W. Fenton, and the authors are indebted to Dr. Fenton for the gift of the samples. The suite consisted of the vitrinites, spore-rich exinites, fusinites and, in one case, the micrinite from five British coal seams of Carboniferous age together with the vitrinites from two coals of higher rank from which it was impracticable to separate the other macerals. The exinites were separated by float-and-sink methods from selected black durain bands, as also... 

Results on Unheated Samples. The results obtained in Southampton for the set of British samples are shown in Figures 2 and 3. In Figure 2 the spin concentration of each maceral is plotted against the carbon content (daf) of the associated vitrinite, and the points for each set of macerals from one coal are joined by a vertical line. It can be seen that the vitrinite series forms a well-defined narrow band which curves upwards sharply at about 90% carbon, and the data resemble closely those presented earlier by Austen and Ingram for whole coals. The values of exinites form a wider, approximately horizontal band lying a little below the vitrinite band, while the fusinite data appear to vary at random but lie consistently well above the vitrinite band and are appreciably higher than vitrinites of the same carbon content (90-92%) would be. 

Fusinites and Micrinite. The fusinites studied in the present investigation were characterized by higher spin concentrations than the macerals associated with them, and the line widths were much narrower. These characteristics did not change much on pyrolysis up to at least 550°C., again in contradistinction to the other macerals. 

Binder phase continuous solid carbon matrix formed during the thermoplastic deformation of those coal macerals that become plastic during carbonization formed from the thermoplastic deformation of reactive (vitrinite and liptinite) and semi-inert (semi-fusinite) coal macerals of metallurgical bituminous coals (ASTM D-5061). 

Fusinite microscopic coal constituent (maceral) with well-preserved cell structure and cell cavities empty or occupied by mineral matter. See also Maceral. 

Inertinite group of macerals composed of fusinite, inertodetrinite, macrinite, micrinite, sclerotinite, and semifusinite. 

Sclerotinite maceral having reflectance between that of fusinite and associated vitrinite and occurring as round or oval cellular bodies or as interlaced tissues derived from fungal remains. 

Semifusinite maceral that is intermediate in reflectance between fusinite and associated vitrinite that shows plant cell wall structure with cavities generally oval or elongated in cross section, but in some specimens less well defined than in fusinite often, occurs as a transitional material between vitrinite and fusinite. 

The preparation of maceral concentrates for study has been achieved by one of two approaches, either by hand picking or by a variety of techniques which exploit the variation in density between the various maceral groups. The first level of hand picking is the judicious sampling of lithotypes. This term is used to identify the various layers found in a coal seam. For humic coals there are four main designations of lithotypes vitrain, clarain, durain, and fusain (42). Vitrain bands are sources of fairly pure vitrinite group macerals while fusinite and semi-fusinite can be obtained from fusain. These are the... 

D. Inertinite macerals, seini-fusinite at left and fusinite at right. 

Given and coworkers studying the "British Macerals" took more of an organic chemist s approach to characterization. The macerals were subjected to solvent extraction, lithium reduction, hydroxyl determination, oxidation, and reaction with various reagents. N-bromosuccinimide (NBS) was used to bromin-ate aliphatic carbons which in the case for four macerals from an Aldwarke Silkstone coal yielded per 100 carbon atoms the following distribution of hydrogen which is replaced by bromine (61) vitrinite 16, exinite 25 1/2, micrinite 12, and fusinite... 

These values were similar to those obtained by the catalytic dehydrogenation (62) of hvA bituminous coal macerals which yielded in atoms of hydrogen per 100 carbons vitrinite 25, exinite 31, micrinite 18, and fusinite 5. Such results would suggest that vitrinites and exinites should be more reactive in thermal processes and indeed this has been found to be true and will be discussed in the section on reactivity. 

Part of this data in Table II is a series of British maceral concentrates. The Woolley Wheatly Lime sample is 93% fusinite while the Teversal Dunsil concentrate is 80% semifusinite with 13% fusinite. The Aldwarke Silkstone sample contains 43% semifu-sinite and 43% fusinite. The petrographic analysis of PSOC-2 reveals nearly equivalent amounts of fusinite, semifusinite, micrinite, and macrinite (6.8, 8.1, 7.5 and 8.5% respectively in the whole coal) while PSOC-858 contains primarily semifusinite as the inertinite. The differences in faH values for these iner-tinite samples are greater than the experimental error and these differences suggest that NMR techniques may be useful in characterizing the chemical structural differences between inertinite macerals. 

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