Method of removing sulphur dioxide from gases, more particularly industrial waste gases

Abstract From the Canadian patent

The disclosure describes a process for the removal of sulfur dioxide from exhaust gases. These gases are treated in a scrubber with a solution containing ammonium sulfite and ammonium bisulfite to absorb the sulfur dioxide. A portion of this solution is drawn off and it is oxidized to form ammonium sulfate. The gas is further treated with the oxidized solution while maintaining the dew point of the further treated gas beneath the temperature of the gas, whereby the escape of ammonia in the further treating process is prevented. This process enables to prevent the loss of ammonia and avoid the use of expensive equipment for further scrubbing of the gas after treatment.