Wegner & Bretschneider
Method of removing sulfur dioxide from combustion exhaust gas
 A method of removing sulfur dioxide from combustion exhaust gas containing sulfur dioxide by contacting the exhaust gas with an aqueous solution containing at least one organic acid salt expressed by the formula EQU RCOOM (wherein R represents H, CH.sub.3, C.sub.2 H.sub.5 or C.sub.3 H.sub.7, and M represents an alkali metal or NH.sub.4) to efficiently dissolve sulfur dioxide contained in the gas in the form of a sulfite in the aqueous solution by reacting the sulfur dioxide with the salt. The resultant solution which dissolves the sulfite may be contacted with a calcium compound for producing calcium sulfite by reaction of the sulfite with the calcium compound thereby effectively removing the sulfur dioxide in the form of calcium sulfite from the combustion exhaust gas. Alternatively, the sulfite-dissolving aqueous solution may be contacted with oxygen or air for oxidizing the sulfite contained in the solution into a sulfate, followed by contacting the sulfate, which is now dissolved in the aqueous solution, with a calcium compound. The sulfate is satisfactorily reacted with the calcium compound to produce calcium sulfate and thus sulfur dioxide may be effectively ultimately removed in the form of calcium sulfate from the combustion exhaust gas. 
Kureha Kagaku Kogyo Kabushiki Kaisha
Tamostu Kenji Tetsuya Koji Shigeru Kunihide
Miyamori Kodama Watanabe Konno Saitoh Yaguchi