Abstract: An apparatus and method for removing very finely divided alkali fumes and other particulate material from a coal-gasifier make-gas comprising the introduction of char granules into the constricted passage of a venturi-shaped gas duct to adsorb the very fine particulate from the make-gas flowing therethrough, and centrifugally separating the fume-laden char granules from the make-gas.

Abstract: 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.