Mercury Control and Mercury Stability in Byproducts - Mercury Emission and its Control in Chinese Coal-Fired Power Plants - page 144

to lose its bond on an object; most of the mercury then escaped. Therefore, it was
not suitable to use AC(MZ) with mercury as a material at high temperatures in
oxygen-rich environments. The two curves intercrossed at ca. 470 °C (Fig. 5.40).
Before this point, the curve of Hg 2+ was always above Hg 0 , indicating that more
Hg 2+ was released than Hg 0 under the same conditions and Hg 0 is more stable than
Hg 2+ on AC(MZ).

100

80

Hg 0
Hg 2+

60

40

20

0

100 200 300 400 500 600 700 800 900 1000

Temperature °C ( )

Temperature (°C)

Fig. 5.40 Mercury released as a function of high temperature

5.5.2.4 Mercury Stability in Actual Fly Ash and AC in a Natural Storage En-
vironment

A simulated experiment of mercury stability in sorbent in a natural storage envi-
ronment was conducted to study the mercury released from actual fly ash and
AC(MZ). Mercury stability in fly ash in natural environments was a short-term
experiment focused on the relation between the mercury release and natural tem-
perature. The results are shown in Fig. 5.41. The experiment on mercury stability in
AC(MZ) in a room environment, was conducted over a period of more than one
year. There was exposure to direct sunlight and the temperature ranged from 6 to
25 °C. The results are shown in Fig. 5.42.
Based on the above, the Hg release was quite low in actual fly ash and AC, with
a release ratio lower than 1.5%. In addition, Hg was stable in both fly ash and AC,
which would not significantly affect the environment.