Removal of Mercury from Gases
by Modified Zeolites in a Stationary Bed
O. PETZOLDT, H.J. FELL, and H.W. BRAuER
1
Introduction
Mercury pollution of the environment caused by humans is in the range of 8000
to 40000 t/a with 6000 to 10 000 t/a of this originating from the mercuryprocessing industry, 2000 to 20000 t/a from ore and mineral processing, and up
to 10000 t/a from combustion of fossil fuels.
For years, the quantities of mercury used industrially have been declining, not
least of all due to the toxicologic classification of this heavy metal with respect to
the environment and above all to human health. Nonetheless, there are still some
areas of use, for instance electronic components, fluorescent lamps, batteries,
thermometers, manometers, or dental fillings, where mercury remains indispensable - at least for the time being.
Contamination of gases with mercury must be anticipated in all thermal
processes that gain application either directly or indirectly in the areas where
mercury is used as mentioned above, for example when incinerating waste.
Several countries have meanwhile placed enacted laws limiting the emission of
mercury in flue gases, the limits in Germany being between 50 and 200 ~lg/m3
depending on the type of plant. Complying with these limits frequently requires
treatment of the gases to remove mercury. This may be done by adsorption as in
the Medisorbon process described here.
2
Problems Involved
Mercury is present in incineration plant flue gases primarily in elemental form as
Hgo and in oxidized form as HgCI2. Possessing a solubility of 73 gil at 25°C,
HgCl2 is well soluble in water and therefore can for the most part be extracted
together with HCL and S02 in the flue gas scrubbers installed for this purpose.
Removal is improved when mercury-combining chemicals are added to the
scrubbing solution.
Environmental Science
Mercury Contaminated Sites (ed. by R. Ebinghaus et a1.)
if) Springer-Verlag Berlin Heidelberg 1999
by Modified Zeolites in a Stationary Bed
O. PETZOLDT, H.J. FELL, and H.W. BRAuER
1
Introduction
Mercury pollution of the environment caused by humans is in the range of 8000
to 40000 t/a with 6000 to 10 000 t/a of this originating from the mercuryprocessing industry, 2000 to 20000 t/a from ore and mineral processing, and up
to 10000 t/a from combustion of fossil fuels.
For years, the quantities of mercury used industrially have been declining, not
least of all due to the toxicologic classification of this heavy metal with respect to
the environment and above all to human health. Nonetheless, there are still some
areas of use, for instance electronic components, fluorescent lamps, batteries,
thermometers, manometers, or dental fillings, where mercury remains indispensable - at least for the time being.
Contamination of gases with mercury must be anticipated in all thermal
processes that gain application either directly or indirectly in the areas where
mercury is used as mentioned above, for example when incinerating waste.
Several countries have meanwhile placed enacted laws limiting the emission of
mercury in flue gases, the limits in Germany being between 50 and 200 ~lg/m3
depending on the type of plant. Complying with these limits frequently requires
treatment of the gases to remove mercury. This may be done by adsorption as in
the Medisorbon process described here.
2
Problems Involved
Mercury is present in incineration plant flue gases primarily in elemental form as
Hgo and in oxidized form as HgCI2. Possessing a solubility of 73 gil at 25°C,
HgCl2 is well soluble in water and therefore can for the most part be extracted
together with HCL and S02 in the flue gas scrubbers installed for this purpose.
Removal is improved when mercury-combining chemicals are added to the
scrubbing solution.
Environmental Science
Mercury Contaminated Sites (ed. by R. Ebinghaus et a1.)
if) Springer-Verlag Berlin Heidelberg 1999