Chemical Composition of Ash
In Table 4-6 some of the major components of various ashes are given. Apart from these there are many trace components present that do not contribute much to the
melting characteristics of the ash but can have a major effect on the environmental problems associated with coal use: for example, mercury, arsenic, zinc, lead, cadmium, chromium, chlorine, and fluorine. Most of the elements present in coal as given in Table 4-7 can appear at least in part in the ash.
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Table 4-7 Detailed Chemical Analysis of Minerals in Coal |
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|
As, ppmv |
2.1 |
|
|
B, ppmv |
35 |
|
|
В a, ppmv |
130 |
|
|
Be, ppmv |
1.2 |
|
|
Br, ppmv |
1.5 |
|
|
Cd, ppmv |
0.07 |
|
|
Ce, ppmv |
24 |
|
|
Co, ppmv |
3.5 |
|
|
Cr, ppmv |
7.0 |
|
|
Cs, ppmv |
0.30 |
|
|
Cu, ppmv |
9.2 |
|
|
Eu, ppmv |
0.32 |
|
|
F, ppmv |
227 |
|
|
Ge, ppmv |
0.50 |
|
|
Hf, ppmv |
1.8 |
|
|
Hg, ppmv |
0.13 |
|
|
La, ppmv |
17 |
|
|
Mn, ppmv |
84 |
|
|
Mo, ppmv |
1.6 |
|
|
Ni, ppmv |
10 |
|
|
Pb, ppmv |
14 |
|
|
Rb, ppmv |
2.1 |
|
|
Sb, ppmv |
0.57 |
|
|
Sc, ppmv |
2.9 |
|
|
Se, ppmv |
3.1 |
|
|
Sm, ppmv |
1.4 |
|
|
Sr, ppmv |
316 |
|
|
Th, ppmv |
8.4 |
|
|
Ті, ppmv |
0.43 |
|
|
U, ppmv |
2.1 |
|
|
V, ppmv |
17 |
|
|
W, ppmv |
0.73 |
Coke is a material consisting essentially of the fixed carbon and the ash in the coal. It was in the past a common fuel in water gas plants, but as it is more expensive than coal, anthracite is now often the preferred fuel. It is virtually never used in gasification plants. Coke plays a very important role in blast furnaces, which may be considered to be very large gasifiers (Gumz 1950). One of the main reasons to use coke in blast furnaces is that it is much stronger than coal.