PROCESSES FOR FLUE-GAS DESULFURIZATION

The continuous high emission of sulphur dioxide from the combustion of fossil fuels is causing increasing damage not only to nature but also to buildings and machinery, especially in industrialized countries. It is possible by desulphurization of the flue gases to reduce the emission of sulphur dioxide by as much as 90%. This can be achieved industrially by dry absorption using activated charcoal or addition of limestone, and by wet processes employing soda, limestone, calcium hydroxide or ammonia as absorbents. The characteristic features of each of the different processes are described. The main residues obtained from these desulphurization processes are gypsum, sulphur, or fertilizer salts, most of which can be recycled.