Environmental Engineering Reference
In-Depth Information
5.5.1.3 Mercury Stability in Desulfurization Gypsum Used in an Environment
at High Temperature
A wide heating temperature range was chosen to study the mercury stability in
desulfurization gypsum used in an environment at high temperature. Four mercury
release curves at 100, 200, 300, and 400 °C are shown in Fig. 5.34. The trend of the
four curves was the same. However, different temperatures had enormous implica-
tions on mercury stability in desulfurization gypsum. 40% mercury in gypsum was
stable at 100 °C for 16 days, 35% - 40% mercury in gypsum was stable at 200 °C
for 20 days, 25% mercury in gypsum was stable at 300 °C for 12 days, and 10%
mercury in gypsum was stable at 400 °C for 12 days.
The key factor that affected mercury stability in gypsum was the initial period of
heating time (Fig. 5.34). The factor that affected the influence of mercury in plaster
was the most stable initial period of heating time. The mercury release phenomenon
was the same at varying high temperatures. The mercury escaped very quickly
during the initial period. The mercury release ratio was much bigger at higher
temperatures. After the initial period when mercury rapidly escaped, the mercury
release ratio dropped due to the stronger adhesion between the remaining mercury
and gypsum.
70
80
(b)
(a)
70
60
60
200
o
C
y
=61.68 + 7.112*ln(
x
-0.04143)
R
2
=0.78166
50
50
40
40
30
100
o
C
y
= 39.945 + 9.331*ln(
x
+0.2708)
R
2
=0.70888
20
30
10
20
0
-2
0
2
4
6
8
10
12
14
16
18
20
-202468 0 2 4 6
Heat-up time (day)
heat-up time (day)
90
(c)
100
(d)
80
80
70
60
60
400
O
C
y
= 81.259 + 8.823*ln(
x
-0.04151)
R
2
=0.91391
50
300
O
C
y
=41.403 + 17.157*ln(
x
+0.14198)
R
2
=0.96916
40
40
30
20
20
0
10
0
2
4
6
8
10
12
0
2
4
6
8
10
12
Heat-up time (day)
Heat-up time (day)
Fig. 5.34
Mercury release at 100, 200, 300 and 400 °C
Search WWH ::
Custom Search