The Babcock & Wilcox Company

Robert E Matty

Robert A McIlroy

Walter C Lapple

Stephen S Strom

A method of absorbing SO.sub.2 by use of an absorbing medium containing ammonia compounds is described. In a process wherein sulfur bearing constituents are combusted, SO.sub.2 bearing flue gases are generated. Having been cooled, the flue gases are contacted in a multi-stage absorption system by aqueous absorbents comprised of ammonium compounds which are maintained so that SO.sub.2 is removed from the flue gas and the formation of the ammonium sulfite fume is inhibited.

Fume control for sulfur dioxide ammonia absorption systems

A new chemical recovery process and apparatus for a polysulfide pulping system is described wherein sulfur is recovered from the weak black liquor and is returned to the process, along with makeup sulfur, to reconstitute the polysulfide solution. After the polysulfide digestion, the spent liquor is contacted with ferric oxide Fe.sub.2 O.sub.3 whereby ferrous sulfide, FeS, is formed. After separation of the ferrous sulfide from the remaining liquid, the ferrous sulfide is oxidized to form elemental sulfur, and ferric oxide. After the melting of the sulfur and the separating of the products, the sulfur can be returned to the Sulfur Dissolving Tank wherein, along with makeup sulfur as required, the white liquor from the causticizing plant can be treated to form the polysulfide liquor for digestion. The ferric oxide can be reused for contacting the black liquor to form ferrous sulfide. The resulting smelt of reduced sulfidity from the recovery furnace can be reprocessed to form the white liquor.

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Alliance, OH, United States of America

Robert E Matty