Abstract: A continuous, low cost method of concentrating dilute streams containing fractions of adsorbable chemicals is disclosed which minimizes heat consumption and provides highly concentrated supplies of valuable chemicals which are suitable for reuse or sale without substantial further processing. The methods hereof are particularly adapted for concentrating waste condensates derived from pulp-making operations such as the Kraft or sulfite processes, but in general are also applicable for treating a wide variety of dilute organic or inorganic adsorbable chemicals.

Abstract: An apparatus and method for the displacement impregnation of cellulosic chips material with digesting liquid. Cellulosic chips material and liquid are fed from a source to a high pressure transfer valve whereat the pressure of the chips and liquid is boosted. The chips are fed from the high pressure transfer valve through a feed system to the topmost portion of a vertical treatment vessel, the vessel having a topmost portion and an impregnation zone in an upper portion thereof below the topmost portion. A countercurrent flow of digesting liquid in the vessel impregnation zone is established to impregnate the chips material with digesting liquid, and displace the water and minerals therefrom, and liquid withdrawn from the top of the treatment vessel is withdrawn into the feed system. The withdrawals insure that essentially no free water enters the impregnation zone. A chips plug is established at the vessel top through which all withdrawn liquid must pass.

Abstract: Plant material containing hemicellulose and lignin is prehydrolyzed in the presence of steam and the vapors of a dilute acid solution having a pH of 1.5-3.5 at a temperature of 105.degree. C to 135.degree. C for 7-20 minutes to hydrolyze the hemicellulose into pentoses and hexoses and to leave a fibrous material and a liquid, said liquid containing said pentoses and hexoses. The liquid is separated from the fibrous material, and the pentoses and hexoses are recovered from the liquid. The fibrous material is digested with white liquor at a temperature of 105.degree. C to 135.degree. C.

Abstract: Oxidation and fixing of sulfur and sulfur compounds in weak black liquor is accomplished by methods which insure minimal odorous sulfur emissions and which facilitate the collection of sulfate soaps. By critical adjustment of certain parameters substantially complete oxidation of sulfur and sulfur compounds is achieved, with maximum utilization of oxygen, while enhancing the collection of sulfate soaps and minimizing the production of foam. Various methods are disclosed for the oxygenation of weak black liquor, including the utilization of reaction columns, conical reactors, and venturis.

Abstract: A process for the disposal of paper pulp mill sludge by incorporating the sludge in the digestion step of a wood pulping operation without detrimental effects on the quality of the pulp obtained. In one aspect, the sludge is surplus sludge which is obtained from a system which microbiologically purifies spent wood pulping liquor by aeration and sedimentation.

Abstract: Soap is separated from spent, cellulosic pulping liquor by strenuously percolating a gaseous, aliphatic hydrocarbon through a quantity of liquor volume under such temperature and pressure conditions that an equilibrious strata of liquid phase hydrocarbon is sustained on the surface of the liquor. Following strenuous combination and agitation, the gas-liquor mixture is allowed to settle so that the entrained, gaseous hydrocarbon and coagulated soap floc gravimetrically rises to the liquor surface and stratifies with the soap layer between the residual liquor solution and a liquid phase layer of hydrocarbon. Thereafter, the liquid hydrocarbon and soap layer are decanted away from the residual liquor solution and depressurized to vaporize the hydrocarbon leaving a reservoir of isolated soap.

Abstract: A low cost, two-stage adsorption-desorption method of concentrating dilute supplies of chemicals is provided which uses a minimum of energy in the form of process steam and yields highly concentrated supplies of end products which are suitable for reuse or sale. The methods hereof are particularly adapted for concentrating waste condensates derived from pulp-making operations such as the Kraft or sulfite processes, but in general is also applicable for treating all types of dilute organic or inorganic adsorbable chemicals. The invention involves first adsorbing a chemical fraction from a dilute stream thereof onto activated carbon, followed by regenerating the adsorbed chemicals and concentrating the same by fractional distillation, whereupon the partially concentrated chemicals are again adsorbed, regenerated, subjected to a second fractional distillation concentration step, and recovered.

Abstract: A method of preventing or reducing the emission of odorous sulphur compounds and/or sulphur combustion products from the black liquor recovery tall oil splitting processes in kraft pulping of pines is described. Sulphur dioxide and/or bisulphite is first reacted with black liquor sulphidic compounds occluded in the soap skimmings simultaneously with the soap acidulation by using a pressure vessel at a temperature of approximately 100.degree.-110.degree. C. Then the sulphite solution with the sulphur compounds thus obtained is separated and further utilized for stabilizing sulphides in various kraft pulping process liquors, preferably the black liquor. Alternatively, the sulphite solution can be passed through a neutral sulphite semichemical (NSSC) pulping arranged for spent liquor cross-recovery with the kraft process. The sulphur dioxide is substituted either for conventionally used acid chlorine dioxide reactor effluent or sulphuric acid. The process may regenerate sulphur dioxide for splitting.

Abstract: Spent sulfite liquor is converted into a nitrogen containing water insoluble product useful as a soil conditioner and fertilizer. The spent sulfite liquor is heated at a temperature of 170.degree. to 260.degree. C to form a partially pyrolyzed water insoluble material and the water insoluble material is then reacted with ammonia at a temperature of 170.degree. to 260.degree. C.

Abstract: Pulping liquor borne solids are concentrated within an aqueous solution by a successive plurality of freezing steps wherein a discrete quantity of the solution is crystallized in each step by freezing. The water crystals from each freezing step are subsequently separated from the remaining liquid solution by screening and applying axial pressure to the crystalline mass. Greater efficiencies may be obtained in some cases by mixing or reslurrying a pressed, crystalline mass and pressing a second time. Another auxiliary separation step comprises a quiescent thaw of the crystalline mass from the first two press steps to permit additional dissolved solids to be drained away from the purified water ice.

Abstract: Char from the waste liquor of a pulp manufacturing process is produced by confining the waste liquor in a container and feeding the container into an air heating furnace in a manner such that the container is contacted countercurrently with heated air without rotating or stirring the container.

Abstract: Increased pulp yields are obtained by alkaline digestion of cellulosic material until a pulp yield of not above 65% is obtained, lowering the pH of the digestion liquid is lowered to allow 11 causing organic substances to precipitate from the digestion liquor and then continuing digestion in the presence of the pulp until at least 5% of the organic substances which have been precipitated out are absorbed by the pulp.