Desulfurization of flue gases with complete sulfite oxidation

A cyclic process for the desulfurization of flue gas having a content of sulfur dioxide with recovery of the sulfur content of said gas as elementary sulfur, which comprises:

• scrubbing said flue gas as a rising stream with a counter-current spray of an aqueous scrubbing solution containing sodium aluminate and sodium hydroxide in 1:1 to 2:1 Na.sub.2 O:Al.sub.2 O.sub.3 equivalent molar ratio thereby removing substantially all of said sulfur dioxide from said gas and converting said scrubbing solution into a spent solution containing sodium and aluminum sulfites and sulfates;
• oxidizing substantially all of said sulfites to sulfates;
• evaporating substantially all of the free water in said solution thereby providing a mixture consisting essentially of sodium and aluminum sulfates;
• reducing said mixture with a carbonaceous reducing agent in the presence of reactive molecular hydrogen thereby forming a mixture comprising sodium oxide and sodium aluminate and a gas comprising sulfur, hydrogen sulfide and sulfur dioxide;
• selectively condensing said sulfur from said gas;
• recovering the gas comprising hydrogen sulfide and sulfur dioxide which remains;
• inter-reacting said hydrogen sulfide and said sulfur dioxide thereby forming elemental sulfur;
• recovering said elemental sulfur;
• dissolving said sodium oxide and sodium aluminate in water thereby forming regenerated scrubbing solution;
• and recycling said regenerated scrubbing solution to said scrubbing step.