Sulfur dioxide removal process

There is disclosed a process for reducing the loss of sodium values in a system for removing sulfur dioxide from a gas by the use of an absorption-desorption cycle employing aqueous sodium sulfite as the essential absorption solution. Sodium sulfate and/or sodium thiosulfate build-up in the system is avoided and the loss of sodium values reduced by subjecting sodium sulfate and/or sodium thiosulfate-containing material to chemical reduction to form a product containing a substantial amount of sodium carbonate. Preferably, the reduced product is subjected to carbonation followed by reaction of the bicarbonate and bisulfide components of the mixture to give a resulting liquid which is more suitable for use in the absorption-desorption process. By-product gases can be incinerated to produce sulfur dioxide-containing gases which can be charged to the sulfur dioxide absorption zone. Sodium thiosulfate can be purged from the absorption-desorption system by treating a purge stream from the desorption zone of the process.