Process for selective dechlorination of waste gases.

摘要

A process for selective dechlorination of a flue gas containing both HCl and SO2 comprises washing the flue gas in a pretreatment zone with a circulating aqueous absorption liquor having a pH of from about 0.1 to about 2.2 and containing magnesium chloride dissolved therein, controlling the pH of the circulating liquor by controlled addition of a magnesium-containing pH controlling agent, and controlling the magnesium chloride content of the said circulating liquor by withdrawing from the circulation path of the aqueous absorption liquor a purge stream of magnesium chloride containing liquor. In a preferred procedure the magnesium chloride is present as a mixture of magnesium chloride and calcium chloride.