Seams, American coal

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. 

Some whole coals in southwest Guizhou province, China (Xingren county) have up to 32 000 mg kg-1 of arsenic (Dai et al., 2005 Belkin, 1998 Ren et al., 1999). Although these coals are primarily responsible for the arsenic poisoning in the province, they are very localized (Dai et al., 2005), 128 (Dai, Zeng and Sun, 2006). Dai et al. (2005) actually found that 71 whole-seam coals from the western portion of the province contained no more than 11 mg kg-1 of arsenic, which is lower than many other Chinese and American coals (Table 3.22). 

Resinite macerals (Anderson et al., 1992) occur widely (often in minor amounts) throughout most American coals below medium-volatile bituminous rank. They are usually absent in coals of higher rank. Although resinite macerals usually make up less than 3% of most US coals, they are particularly abundant in coal of the Wasatch Plateau in Utah where they can account for as much as 15% of the macerals present. In most Appalachian and mid-western US coal seams, resinites occur as primary (present at the time of deposition) ovoid bodies with a long axis ranging from 25 to 200 jm. While primary ovoid bodies of resinite are also found in western US coals of Cretaceous/Tertiary... 

Considerations of process simplicity as well as economy suggest that the waste heat produced by the fuel cell (about 0.25 kW per kW of net electrical DC output) should be fed back to thermally decompose the raw coal feed. This requires that the cell produce sufficient heat at a sufficiently high temperature to effect thermal decomposition within a time span that is short compared with that of electrochemical conversion. Fig. 8 (after Howard, 1981) reproduces data underlying Dryden s correlation (Dryden, 1957) for many British and American coal seams and shows the extent of decomposition (relative to that at prolonged pyrolysis at 1000°C) as a function of temperature and time. The reference to 1000 C is useful, as the yields observed at this temperature approach those of higher temperature asymptote. Also in Fig. 8 is the data from Anthony et al. (1975) taken after various exposure intervals between 0.1 and 14400 s, showing that devolatilization is 90% complete in the range of 5-20 s. 

The numerical model adopts FLAC3D numerical simulation software developed by American Itasca Company. The model has a embedded depth of 1100 m, and its length x width x height is equal to 200 m X 120 m x 150 m. The coal seam dip angle has four circumstances covering 15°, 35°, 55° and 75°. Figure 1 is the numerical calculation model with the coal seam dip angle of 35°, and the model... 

FIG. 6.3. This American diagram presents an idealized picture of the strata or rock layers above the coal seam in the mine. Source U.S. Ctepartment of Labor, Mine Safety and Health Administration, National Mine Health and Safety Academy (1989). 

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