Abstract: A composition having sodium bicarbonate, sodium carbonate, and ammonia in the form of ammonium salts is formed by heat treating ammoniacal bicarbonate at a temperature between 20 and 150° C. A method of using the composition includes reacting the composition with a flue gas containing HX acids, where X represents halogens, compounds of the SOx type, or mixtures thereof, or the flue gases may contain NOx compounds.

Abstract: A method for removing contaminants, such as sulfur dioxide, mercury and hydrochloric acid, out of flue gases is provided, said method including the steps of: treating the flue gases with a reagent, such as sodium carbonate, sodium bicarbonate and ammonium salts or mixtures thereof; selectively dissolving the sodium phosphates produced thereby in water; separating out the solids remaining in suspension in the solution; and crystallizing the purified sodium sulphate present in the above-mentioned solution. The sodium sulfate can be upgraded in glass working furnaces. The reagent can be obtained by heating an intermediate solution containing sodium bicarbonate; sodium carbonate; ammonium bicarbonate and ammonium carbonate, which was obtained from the Solvay process for manufacturing sodium carbonate.