Geology Reference
In-Depth Information
Table 4.1.4
(continued)
Major oxides and trace elements of materials in study area
*
Material
Ash
Ash
Ash
Ash
Algorrobo wood Charcoal
Plant data
Peru coal
Tschudi burn Tschudi burn Tschudi burn Chao valley
Trujillo market
Field no. Average
BP0701
BP0801
BP0901
BP0101
BP0601
Lab no.
(Table 3)
E-199457
E-199458
E-199459
E-199743
E-199456
Y
42.8
13.4
14
13.2
10.1
8
NA
B
157
102
55.8
20
306
284
NA
<<
Cd
3.23
0.21
0.25
0.1
7
0.1
NA
<<
Ge
4.13
1.9
2
1.9
0.52
1
NA
Nb
19.1
7.6
11.3
8
0.76
4.1
NA
Pb
156
10
11.4
12.5
598
7.2
NA
Te
1.5
0.11
0.18
0.1
0.1
0.36
NA
<<
<<
Tl
1.14
0.37
0.23
0.11
0.23
0.11
NA
Se
1.14
0.63
0.62
0.10
0.05
0.10
NA
<<
<<
<<
Ba
601
378
360
348
112
174
NA
Note
: Bold-faced data are necessary for determining the original fuel.
NA, not available.
*
Oxides are in weight percent (wt %); trace elements are in parts per million (ppm).
necessary for plant cell manufacture and development (Tucker, 1995). Analyses of charcoal, coal, and peat ash by
Tylecote (1980, p. 205) (Table 4.1.4) showed that the combined content of CO
2
,K
2
O, and Na
2
O was 22 wt% for
charcoal, 1.0
-
2.0 wt% for coal ash, and 0.6
-
4.0 wt% for peat ash, and those oxides can be used to chemically
differentiate the fuels.
The abundance and importance of potassium, sometimes referred to as the compound
(K
2
O), is indicated
by the use of ashed hardwood trees to provide an abundant source of potash for fertilizer (Craig et al., 2001, p.
339). The principal elemental components of wood ash are calcium, potassium, and nitrogen
“
potash
”
potassium is one of
the chief components of fertilizer. In general terms, wood charcoal and plant or peat ash would have higher CaO
and K
2
O content relative to coal ash.
—
Zr
This element is commonly found in the mineral zircon (ZrSiO
4
) and may enter the coal basin as a detrital grain
weathered from igneous, metamorphic, or sedimentary rocks or as wind-blown material from a volcanic eruption.
Zircon is a heavy mineral (specific gravity 4.6
—
4.7) with a hardness of 7.5 and, therefore, would resist abrasion in
streams and would not degrade during the coal-forming process. The zirconium signature of coal ash is high and
may range from 130 ppm to 2400 ppm (Finkelman, 1981, p. 269). But equally important, the mineral zircon is
geologically stable and highly refractory to temperatures of 2500°C (Blumenthal, 1995, p. 860) and is used as
foundry sand. Therefore, because of its refractory nature, the zirconium content of wood or coal would not be
affected by ashing in the laboratory or by burning, for example, at the 1320°C Tschudi burn, and, therefore, would
provide an important elemental signature of the unburned fuel.
-
There is a paucity of data on zirconium in plants and not much agreement among the reported values for
zirconium plant data; however, a concentration of 10
20 ppm zirconium was given by Kabata-Pendias and Pendias
(1992, p. 2001). Zirconium data on plants in the United States showed that beans and corn contained
-
20 ppm
<
zirconium and some trees contained
20 ppm to 60 ppm zirconium (Connor and Shacklette, 1973, p. 167). Land
plants have little tendency to use zirconium and 70% of plants analyzed had no zirconium present (Lenntech,
1995).
<
The results indicate, that in relative terms, the zirconium content of an ashed plant fuel would be low, approximately
20 ppm, relative to the higher zirconium content of coal ash, from 130 ppm to as high as 2400 ppm. The data in Table
