Abstract: A process for recovery of chemicals from a sodium sulfite pulping waste liquor is disclosed in which a smelt obtained from the waste liquor is introduced into an aqueous slurry containing solidified smelt while make up water and a weak aqueous slurry are supplied to effect incomplete dissolution of the smelt into the aqueous slurry to maintain the content of total solid and the temperature of the slurry at constant levels, the resulting aqueous slurry is subjected to a solid-liquid separation to obtain a wet cake having the molar ratio of S/Na.sub.

Abstract: Sodium bisulfite, for use in the acid digestion of wood to produce pulp is obtained for the process by passing calcium bisulfite through a strong cation exchange resin in the sodium form and regenerating the exchanger with sodium chloride. The calcium bisulfite for the process can be obtained in a known manner, for instance, in an acid tower of the sulfite pulp industry or by passing sulfur dioxide through milk of lime. The process avoids environmental pollution caused by the usual discharge into streams of waste calcium salts from the older sulfiting processes and by the release into the atmosphere of sulfur dioxide containing combustion gases.

Abstract: A process is provided for reducing the requirement of fresh chemicals without increasing emissions in the pulping of cellulosic material with alkaline sodium- and sulfur-containing-sulfate pulping liquor, which comprises evaporating and burning spent sulfate pulping liquor to obtain a smelt; dissolving the resulting smelt in water to form a sodium-sulfide-sodium carbonate-containing solution green liquor; regenerating pulping white liquor containing sodium sulfide and sodium hydroxide from said green liquor; and recirculating said regenerated white liquor to the pulping stage; oxidizing at least one of the resulting green and white liquors to form sodium thiosulfate therein; reacting the oxidized liquor with residual acid liquor, from the manufacture of chlorine dioxide by reduction of an alkali metal chlorate solution, to convert thiosulfate to sulfur dioxide and sulfur; removing and recovering formed sulfur dioxide; and returning the residual liquor, freed from sulfur dioxide, to the pulping.

Abstract: A method of removing and preferably recovering sulfur values from an alkali metal sulfide and carbonate mixture comprising the steps of (1) introducing the mixture in an aqueous medium into a first carbonation zone and reacting the mixture with a gas containing a major amount of CO.sub.2 and a minor amount of H.sub.2 S; (2) introducing the resultant product from step 1 into a stripping zone maintained at subatmospheric pressure, and contacting this product with steam to produce a gaseous mixture, comprising H.sub.2 S and water vapor, and a liquor of reduced sulfide content; (3) introducing the liquor of reduced sulfide content into a second carbonation zone, and reacting the liquor with substantially pure gaseous CO.sub.2 in an amount sufficient to precipitate bicarbonate crystals and produce an offgas containing CO.sub.2 and H.sub.

Abstract: Waste water streams containing sulfite and bisulfite ions but substantially no sulfide or thiosulfate ions are treated to convert sulfites to sulfates which can be discharged in receiving streams with no concomitant increase in Chemical or Biological Oxygen Demand. The process is a non-catalytic oxidation effected at 25 to 50 psi, 175.degree.-250.degree. F using from 50 to 350 percent excess of oxygen when utilizing air or any suitable oxygen containing gas basis stoichiometric conversion of sulfite to sulfate.

Abstract: A process and apparatus for treating concentrated alkali metal-containing waste liquor to recover the alkali metal content for reuse includes the following steps and apparatus. Concentrated alkali metal-containing waste liquor is mixed with recycled alumina and formed into solid pellets by mixing the concentrated liquor-alumina mixture with recycled alkali metal aluminate furnace ash. The solid pellets are fed through a furnace operating at a temperature below the fusion temperature of the aluminate for combusting the organic portion of the pellets and reacting the alkali metal content thereof with the alumina to form additional alkali metal aluminate ash. A portion of the furnace ash is recycled for reuse in the formation of pellets, while another portion of the ash is dissolved in water to form a solution of alkali metal aluminate. The alkali metal aluminate solution is mixed with slurry recycled from later in the process to initiate limited precipitation of alumina from the alkali metal aluminate.

Abstract: The invention relates to a continuous method of making cellulosic pulp from wood chips within a range of yield from 65 to 90 per cent by digestion with a digestion liquor containing Na.sub.2 S and Na.sub.2 CO.sub.3. The digestion is effected at temperatures between 150.degree. and 190.degree.C and malodorous sulfur compounds are removed from the pulp, the liquor and the vapors prior to their withdrawal from the digesting process. In order to eliminate their capacity of emitting obnoxious odors, the sulfur compounds are oxidized by addition of molecular oxygen to the digester prior to discharge of pulp and spent liquor from the digester after which the spent liquor is removed from the digested pulp, concentrated and burned for renewed use in preparation of fresh digesting liquor.

Abstract: Method for disposal of water soluble sodium sulfur oxide-containing wastes resulting from industrial processes producing fly and/or bottom ash from fossil fuel utilization and waste or excess sodium sulfur oxide compounds, particularly disposal of sodium sulfite and/or sodium sulfate resulting from wet or dry sodium alkali scrubbing of tail or flue gases to reduce SO.sub.x emissions therefrom as from smelters, power plants, paper plants, glass plants and industrial boiler operations. Process involves mixing sodium sulfur oxide wastes with an alumina and silica-containing fly ash and/or bottom ash, forming an agglomerate, such as a pellet or briquette, and sintering in the range of about (1000.degree.-2300.degree.F). The resultant sintered particle shows lower solubility than the current standard of calcium sulfate, being 10.sup..sup.-2 to 10.sup..sup.-4 as soluble as the starting sodium sulfur oxides, has increased density (as high as 2.