Method for controlling elemental mercury emissions

A method for controlling mercury emissions in an industrial process having a flue gas containing insoluble elemental mercury at a concentration between 5-30 μg/Nm3, the method comprising:

• a) providing the flue gas to a wet scrubber having an aqueous alkali scrubbing liquor;
• b) mixing the flue gas with an oxidizing reagent containing chlorine in an amount that is at least double a stoichiometric ratio normally required to oxidize all of the insoluble elemental mercury present in the flue gas;
• c) mixing the flue gas with a sulfide species, said sulfide species provided in an amount sufficient to convert the soluble mercury species into insoluble mercuric sulfide;
• d) wherein step (b) and step (c) occur separately using an interspatial header, so as to avoid unwanted reactions directly between the chlorine and the sulfide species;
• e) creating a gas-liquid interface within the wet scrubber in order to:
• (i) entrain the insoluble mercuric sulfide generated by step (b) and step (c) within the scrubbing liquor and (ii) remove all mercury species from the flue gas;
• and
• f) evacuating the mercury-free flue gas from the wet scrubber.