a synthetic flue gas, spiked
with 2000 mg/m³STP SO2, is brought into contact with the circulating slurry in a countercurrent process at
a temperature of 60 °C. In the stirred and aerated sump, the forced oxidation of the absorbed sulfite
species takes place. The pH-value in the sump is controlled to a value of 5.1 by dosing CaCO3 slurry. The
3.5 wt.-% solid content of the slurry consist of 99.9 % gypsum. Aqueous concentrations are adjusted to
250 μg/l Hg2+ and 0.5 – 15 g/l Chloride (Cl-) by dissolution of reagent grade chemicals and validated by
AAS and IC respectively. In the first stage of the experiments, the FGD is operated under reference
conditions. Once steady state is reached, the slurry is removed from the FGD and subsequently separated
by filtration. The liquid phase is directed to the electrically heated alkalization reactor, equipped with
online redox- (ORP) and pH-monitoring. Alkalization is performed by addition of a Ca(OH)2 solution. An
adjustable air flow is bubbled through the liquid, monitoring its increase in Hg0-concentration as a
function of experimental parameters. The Hg-rich air flow is directed to an activated carbon adsorber.