Dull coal

Matt-kohle, /. dull coal, -kunstseide, /. de-lustered rayon, -lack, m. flat (dull, mat) varnish or lacquer, mattrosa, a. dull pink, mattrot, a. dull red. 

Concerning the distribution of degradofusinites, M. Teichmuller states (26) "By far the greatest part of Carboniferous and Permian fusinite and semifusinite occurs in dull coal bands (du-rains). These fusinites, in contrast to the fusain lenses, are not visible macroscopically. Their cell structures are poorly... 

Block coals" are dull coals that break into large blocks because they have fewer vitrain and clarain bands, but have a composition higher in liptinite macerals, which are tough. 

Bone" and "bone coals" have a high ash content in the form of clays and silts they form part of a continuum between dark shale and dull (banded or non-banded) coal in the following sequence dark shale, bone (greater than 50% ash), boney coal (less than 50%), dull coal (cannel, boghead, or splint). 

The general appearance in the electron microscope of an ultrathin section of a heterogeneous area of dull coal (high volatile A bituminous) is illustrated in Figure 1. Components readily identifiable as vitrinite, exinite, and granular micrinite are indicated. Distinguishing the other variously shaded areas is not so positive, but identification can usually be established from shape, density, and association. 

For several years the structural features of a vitrinite (83.9%C) have been intensively studied. The two macerals, exinite and micrinite, which accompany the above mentioned vitrinite in the dull coal were also examined. 

Separating the three macerals from the dull coal was difficult. The petro-graphical purity of the exinite is 86% and that of the micrinite 94%. For both macerals, vitrinite is the main impurity. Since the vitrinite has a petrographi-cal purity of 99%, it is not difficult to calculate the values for the pure exinite and pure micrinite from the experimental data on the highly enriched maceral fractions. All values reported in the tables are corrected ones. Table I summarizes the results of elementary analysis (maf) and the percentage of volatile matter. 

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. 

Vitrain W2 Bright banded coal V/A Subbright banded coal I 1 Dull coal Fusain... 

Cosmic Black DB pigment, dull coalings Catbilal 35 pigment, dyeing... 

Fusain, a constituent of dull coal, occurs predominantly as patches (or wedges) that are parallel to the bedding plane. Fusain consists of powdery, fibrous strands which can be easily fractured and separated from the coal mass. On the other hand, durain is hard with a close, firm texture and may even appear granular to the naked eye. It appears as bands of variable thickness which may be parallel to the bedding plane and which may contain intercalated bands of clarain. 

Dull coal Coal that absorbs rather than reflects light, containing mostly durain and fusain lithotypes. 

Coals are also divided into two types based on their macroscopic appearance banded and non-banded. Non-banded coals include cannel and boghead coals, both of which are dull and blocky. 

Ileat employed for coal-gas,, Dull re cl-hpAf-. . Cubic foot. -10-. . 640. CnUo fteti 1 2. FercttMa foot. 2 45 , ., Ooft-half. 

The Antarctic coal beds are apparently less persistent, and locally may be thicker, than many of the beds in Paleozoic coal fields of North America. It is hazardous to generalize about petrographic composition from hand specimens that are available from many of the coal beds, but one obtains the impression that dull, moderately dull, and midlustrous attrital layers are more prevalent than in Paleozoic coal of the Northern Hemisphere. Vitrain bands tend to be relatively sparse and thin fusain chips and partings generally are present and may be abundant. Many coal specimens are relatively impure, apparently owing to well-dispersed detrital mineral matter. 

Figure 1. Electron micrograph of an ultrathin section of a dull attrital layer (durain) in a high volatile A bituminous (hvab) coal. V—vitrinitey E—exinite, M—granular micrinite. X 10,500...

Macroscopic Appearance. Lignitic coals vary from brown to dull black when moist, although Lite color ntay appear considerably lighter when the coal is dried. Breakage is easiest fur the unconsolidated coals. Strength and toughness increase as cualiliealion increases. 

Coke (Coke in Fr or ftal Cok or coque in Span Koks in Ger or Rus). Coke is the solid residue which remains when certain types of bituminous coals are heated in retorts or special ovens (such as "behive type) to high temps out of contact with air until practically all of the volatile constituents are removed. Coke consists principally of C and of small amts of S, H, N, O mineral matter present in the original coal. It is a hard, cellular form, porous substance, ranging in color from silvery gray to dull black. Its true density 1.85 -1.90, is higher than that of coal, but its bulk d is lower because of porosity... 

Bituminous coal is a dense coal, usually black, sometimes dark brown, often with well-defined bands of bright and dull material, used primarily as fuel in steam-electric power generation, with substantial quantities also used for heat and power applications in manufacturing and to make coke. The moisture content of bituminous coal is usually less than 20% by weight. The heat content of bituminous coal ranges from 21 to 30 million Btu/ton on a moist, mineral-matter-free basis. 

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