Low-volatile bituminous coal

Aromaticity of coal molecules increases with coal rank. Calculations based on several models indicate that the number of aromatic carbons per cluster varies from nine for lignite to 20 for low volatile bituminous coal, and the number of attachments per cluster varies from three for lignite to five for subbituminous through medium bituminous coal. The value is four for low volatile bituminous (21). 

Fig. 10. Coal fields of the conterminous United States where H represents anthracite and semianthracite low volatile bituminous coal medium and...

Low volatile bituminous coal and high volatile anthracite coal 11,000-14,000... 

Low volatile bituminous coal and high volatile anthracite coal Subbituminous coal Lignite Coke and coke breeze Wood Bagasse (dry) 11.000- 14,000 9.000- 11,000 7.000- 8,000 12.000- 13,000 8.000- 9,000 7.000- 9,000... 

The tendency to coke formation also increases again, as might be expected, in the liquefaction of medium and low volatile bituminous coals. 

Low volatile bituminous coal rank and heating values, 6 726t vitrinite reflectance limits and ASTM coal rank classes, 6 708t Low volatile bituminous coal grade (U.S.), 6 713t... 

Moj pyrograms of a high-volatile bituminous coal (E), a low-volatile bituminous coal (F) and a semi-anthracite (G). 

Pocahontas 3 low volatile bituminous coal, Illinois 6 high volatile bituminous coal, Wyodak subbituminous coal, and Beulah-Zap lignite from the Argonne Premium Coal Sample Bank were used as feed coals m these experiments. Ultimate analyses for these coals are listed in Table I. Coal samples were stored under argon in sealed ampules prior to use in pretreatment and liquefaction experiments. 

Let us take another example. At the U.S. Gulf Coast, the Pleistocene and the Upper Tertiary (Pliocene and Miocene) reach a thickness of more than 6000 meters. Nevertheless, the coaliflcation has only reached the stage of high volatile bituminous at this depth. This observation resulted from our studies of samples from a deep borehole located in Terrebonne Parish, La. By reflectance measurements on humic inclusions in claystones of the uppermost Middle Miocene encountered at a depth of 5440 meters, we obtained a mean value (under oil) of 0.95% reflectance, which is equivalent to the reflectance of vitrinites (out of deep boreholes) with 35-40% volatile matter (daf). On the other hand, we found low volatile bituminous coals (14-16% volatile matter, daf) at a depth of 5100 meters in a borehole in the Lower... 

With increasing rank, the differences between macerals become progressively smaller in electron as in light microscopy. Exinite in particular becomes difficult to distinguish in medium volatile coals, and could not be positively identified in the electron micrographs of low volatile bituminous coals so far examined. Similarly, the laminate structure of vitrinite described above could not be observed in low volatile bituminous coals. 

In an attempt to make any such structures visible in coals of low volatile bitunynous rank, replicas were prepared of both polished and natural fracture surfaces (Figure 6). Indications of such structures were obtained with medium volatile but not with low volatile bituminous coals. Replicas of naturally frac-... 

This procedure has now been extended to a series of coals varying in rank from lignite (70% C) to a low volatile bituminous coal (91% C). In addition to determining the amount of aromatic and aliphatic hydrogens, the aromatic group will be further subdivided into monocyclic and polycyclic types. A more... 

Figure 7 shows carbonized coal particles of the sieve fraction 5 to 3 mm. It can be seen that for all types of coals practically all particles display devolatilization pores. This result, obtained by counting, is particularly interesting for the low volatile bituminous coal (No. 6 in Figure 7) because in high temperature cokes produced under normal conditions from another coal of the same rank, the particles of carbonized coal show no pores and will be found as so-called unmelted particles in the coke. 

Attempts have been made to correlate the friability of coal with rank (Table 8.4). Thus, lignite saturated with moisture was found to be the least friable, and friability increased with coal rank to a maximum for coals of the low-volatile bituminous coal. The friability of anthracites is comparable with that of... 

Bituminous class class of rank consisting of high-volatile C bituminous coal, high-volatile B bituminous coal, high-volatile A bituminous coal, medium-volatile bituminous coal, and low-volatile bituminous coal. 

Low-volatile bituminous coal rank of coal within the bituminous class such that on a dry, mineral-matter-free basis, the volatile matter content of the coal is greater than 14% but equal to or less than 22% (or the fixed carbon content is equal to or greater than 78% but less than 86%), and the coal commonly agglomerates. 

Explosibility of semi-anthracite, low-volatile bituminous-coal, and medium-volatile bituminous-coal dusts. U. S. Bur. Mines Rept. Investigations 3489. 

The inner part of the scattering curves for the anthracites is very similar to the corresponding region of Curve 3 in Fig. 1. The macropore structure in anthracites thus is probably quite similar to that in low-volatile bituminous coals. 

The fact that the 9.8 G coupling is observed for the subbituminous and high-volatile bituminous coals, which have high heteroatom contents (18.5 wt % and 11.4 wt %, respectively (35)), andmot for the low-volatile bituminous coal, which contains only 3.6% (35), suggests that its assignment to a heteroatomic radical is not unreasonable. 

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