Method for removing mercury and sulfur dioxide from gases

A process for the removal of gaseous mercury and gaseous sulfur dioxide out of a flue gas, comprising:

• passing the flue gas into a scrubbing vessel;
• passing an aqueous washing liquor, which contains an oxidizing agent in such an amount that the red/ox potential of the washing liquor is between 600 and 800 mVolts (SCE) and which also contains chloride ions in an amount of at least 1 gram/liter, into the scrubbing vessel so that the flue gas and the washing liquor are contacted cocurrently, and the gaseous mercury is sorbed into the aqueous washing liquor and converted into mercury (II) chloride species and the gaseous sulfur dioxide is sorbed into the aqueous washing liquor and converted into sulfuric acid;
• subsequently, passing the flue gas and the resulting, mercury (II) chloride species and sulfuric acid-containing, aqueous washing liquor through a bed of calcium carbonate solids, within said scrubbing vessel, so that the sulfuric acid reacts with the calcium carbonate to produce calcium sulfate, which is washed off the surfaces of the calcium carbonate solids into the aqueous washing liquor, thereby resulting in an aqueous washing liquor containing mercury (II) chloride species and calcium sulfate;
• a bed of calcium carbonate solids with exposed calcium carbonate surfaces, and a cleaned flue gas, and
• discharging the cleaned flue gas out of the scrubbing vessel, and collecting the mercury (II) chloride species and calcium sulfate-containing, aqueous washing liquor in a collection sump, which is located at the bottom of the scrubbing vessel.