Abstract: A method for the production of delignified wood pulp is provided which result in said pulp's having improved delignification ratios. In accordance with preferred embodiments, brownstocks are substantially uniformly treated with aqueous alkaline solution while in a state of low consistency. The consistency is then increased to values preferably in excess of about 20% and the brownstock treated with oxygen to effect delignification. The processes of the invention provide surprising improvements over prior methods in the high strength, low lignin containing pulps may be formed thereby. These pulps can be further bleached to high brightness with less subsequent bleach chemical.

Abstract: A method for the screening of defibred pulp bleached in several steps. In the method, the pulp coming from an acidic bleaching step (2) is screened (3, 4, 5, 6) at the same time as it is treated with an alkali. In this way, no separate alkali stage is needed.

Abstract: Resin is removed from mechanical pulps, such as TMP, CTMP, and the like, in a quick and simple manner. Mechanical pulp at a consistency of about 7-20 percent (preferably 8-15 percent) is subjected to high turbulence. The high turbulence may be effected by fluidizing the pulp, as in a centrifugal fluidizing pump, or otherwise by subjecting it to high turbulence as in a mixer, screen, or disc mill refiner. By subjecting the pulp to high turbulence treatment for a time period of about 0.2-10 seconds, resin removal is greatly enhanced, and in subsequent dewatering of the pulp a pressate is formed which has a higher concentration of resin in the pressate than in pressates produced by conventional processes. After dewatering the pulp is preferably diluted (again to about 7-20 percent consistency), and the turbulence and dewatering steps are repeated. Chemicals to improve deresination can be added to the pulp while it is subjected to high turbulence.

Abstract: Method and apparatus for delignifying chemical pulp by means of oxygen, in which an aqueous slurry of chemical pulp is formed, then mixed with a caustic agent, followed by contact with a delignifying fluid. Water is drained off the slurry without reduction of pressure and while maintaining temperature following which the resulting slurry is maintained under these temperature and pressure conditions for a discrete period of time. The thus-obtained treated slurry is then washed.

Abstract: Lignin is precipitated in high yields and at high rates from a black liquor produced by pulping wood at high temperatures and pressures with an aqueous lower aliphatic alcohol solvent. The lignin is precipitated by diluting the black liquor with water and an acid to form a solution with a pH of less than about 3, an alcohol content of less than about 30% by volume and a temperature of less than about 75.degree. C. The precipitated lignin, when subsequently dried, is in the form of a powder which requires little or no crushing to convert it into a fine uniform size suitable for use without further significant processing.

Abstract: Air is removed from wood chips, and they are impregnated by treatment liquid, in a process that is an alternative to presteaming and is particularly applicable to environments where presteaming is undesirable, such as in the sulphite treatment of chips during the production of mechanical pulp. The chips are passed in a continuous manner in a generally serpentine, vertically oriented path so that the chips are subjected to a pressure build-up pulsation as they move downwardly, and a pressure release pulsation as they move upwardly. The diameters or cross-sectional areas of the conduit portions defining the upward and downward portions of the path are controlled so that there is about twice the residence time during pressure build-up than there is during pressure release. A high pressure feeder and pump with a fly wheel are operatively connected to one end of the serpentine path, while an in-line drainer and other apparatus are connected to the other end.

Abstract: A method for the treatment of a suspension, such as pulp, with one or more treatment liquids in a manner that maximizes treatment efficiency and minimizes heat loss. The pulp flows in a flow path confined to a given web thickness, and has first and second opposite sides. Treatment liquid is added to the first side of the flow path at spaced predetermined points along its length. Liquid displaced by the treatment liquid is withdrawn from the second side of the flow path at substantially the predetermined points. The displaced liquid at the first predetermined point along the flow path consists essentially of original suspension liquid, while the liquid fraction of the pulp past the last predetermined point of the flow path is composed mainly of treatment liquid added at the last predetermined point. Treatment can be accomplished at super-atmospheric pressure and at a temperature above 100.degree. C. The web thickness is between about 50-500 mm.

Abstract: A process is provided for delignifying bleaching lignin-containing cellulose pulp which comprises:(1) activating cellulose pulp by reacting the pulp at a pulp consistency within the range from about 20% to about 60% and at a temperature within the range from about 20.degree. to about 130.degree. C. with a gas comprising NO.sub.2 and oxygen in the presence of water, sodium nitrate in an amount of at least 0.15 g mole per kg of water, and optionally nitric acid;(2) washing the activated pulp with water or an aqueous solution; and(3) treating the activated washed pulp with an aqueous alkaline solution at a temperature within the range from about 70.degree. to about 170.degree. C., optionally in the presence of oxygen gas until the lignin content of the pulp is so reduced that the Kappa number of the pulp is within the range from about 10 to about 60% of the Kappa number of the pulp entering the activating stage (1).

Abstract: Method and apparatus for pulp bleaching at several bleaching stages by utilizing two or more different bleach chemicals. Bleach chemical (E) is in turn led to the pulp so that it displaces of pulp the chemical used at the preceding stage (C/D, D). Displacing chemical (E) is led to the pulp sheet when on the filtering area of a multi-stage drum washer (1, 2).

Abstract: A process for the delignification and bleaching of chemical and semi-chemical cellulosic pulps in which the pulp is subjected to a treatment with oxygen and a subsequent treatment with peroxide. The effluent from the treatment with peroxide is at least partially recycled to the treatment with oxygen.

Abstract: A method is disclosed for delignification of ligno-cellulose containing fiber material comprising mixing an oxygen-containing gas with the cellulose fiber material so as to atomize the gas and form a foam of the gas and the cellulose fiber material, and without an intervening oxidation step, subjecting the foam to upwardly flowing, substantially non-pressurized, alkali extraction. The alkali extraction step is conducted at a temperature of from about 40.degree. to about 80.degree. C. and at a pH, ligno cellulose containing fiber concentration and oxygen containing gas concentration sufficient to provide a bleached, delignified cellulose fiber without bleaching the lignin substance extracted from the material and to suppress lignin condensation reaction during the extraction.

Abstract: A process for delignifying bleaching cellulose pulp in three stages, an activating stage, and first and second alkaline stages, NO and/or NO.sub.2 and O.sub.2, and optionally HNO.sub.3, being supplied to the water-containing pulp in the activating stage; in the first alkaline stage, alkali being supplied as carbonate, primarily HCO.sub.3.sup.-, with oxygen gas having a partial pressure, on average, of from 0 to 0.2 MPa, the lignin content of the pulp being lowered in this stage so that the Kappa number of the pulp after the stage is from 10 to 60% of the Kappa number of the pulp entering the activating stage; in the second alkaline stage, alkali being supplied as carbonate, primarily CO.sub.3.sup.=, with oxygen gas at a partial pressure, on average, of from 0.1 to 3 MPa.

Abstract: A process is provided for the bleaching delignification of cellulose pulp with oxygen gas in the presence of alkali, wherein the pulp is first activated with nitrogen dioxide and then washed, preferably with water. The invention is characterized in that the acid solution obtained is used to pretreat the digested pulp subsequent to washing the pulp with waste liquor obtained from the oxygen gas bleaching delignification stage.

Abstract: A process for producing corrugating medium pulp, fuel, and other products from a wide variety of woody materials is disclosed. In one embodiment a pulping solution is produced by cooking green chips in a water solution of monoethanolamine and subsequently collecting the liquor produced. Pulp is then produced by digesting chips under a vapor dome of the pulping solution, or cooking the chips in the solution and subsequently digesting under a vapor dome. Digested chips are then refined in pulping solution to produce corrugated medium pulp. In another embodiment, fuel may be produced by digesting woody material under a vapor dome with sulfur dioxide and ammonia. The digested chips then yield a lignin containing liquor which has a good fuel value and may be used as a liquid fuel or impregnate for woody material. In another embodiment the pulping solution is used as a hard wood conversion resin. Wood is impregnated and pressed. The pressed wood may have a density of twice the original wood.

Abstract: A chlorine-free bleaching process for lignocellulosic pulp characterized by a series of bleaching stages comprising in sequence a peroxide bleaching stage, the peroxide being selected from the group consisting of alkaline hydrogen peroxide, acidic hydrogen peroxide, and peroxy acid and at least one ozone bleaching stage and in one embodiment the sequence including an initial oxygen bleaching stage before the peroxide bleaching stage. In continuous operation the effluent from each of these sequential stages provides the preferred wash for the preceding washing step and the diluent for the preceding bleaching stage, the final effluent being recyclable for effective closed cycle operation.

Abstract: A process is provided for the alkaline oxygen delignification and bleaching of chemical cellulose pulp while inhibiting degradation of carbohydrates in the pulp, due to the presence of one or more aromatic diamines, preferably having the diamine groups directly linked to an aromatic ring.

Abstract: Lignocellulose is treated with an alkaline pretreatment liquor containing anthraquinone or other pretreatment agent in a continuous process in which the lignocellulose and pretreatment liquor flow countercurrently. The pretreatment agent is substantially soluble in the pretreatment liquor introduced into the pretreatment zone and is substantially insoluble in the pretreatment liquor withdrawn from the pretreatment zone, with the result that the pretreatment agent is effectively recycled within the pretreatment zone.

Abstract: A process is provided for the manufacture of bleached chemimechanical cellulose pulp in high yield of between 65 and 95% from particulate and preferably washed lignocellulosic material, such as wood chips, featuring the use of spent or waste bleaching liquid, preferably from a lignin-preserving bleaching process, in at least one stage of the process where a cooling and diluting liquid is required, such as during mechanical defibration of the material.

Abstract: A method and apparatus for the treatment of fiber material by oxygen bleaching. Digested cellulosic fiber material is treated with oxygen to reduce the Kappa number thereof further to about 15 or below. The reaction products are removed immediately after formation, and during the oxygen bleaching process. The fiber material is at a first consistency of about 8 to 15% consistency, and treatment with oxygen is accomplished by mixing the pulp with O.sub.2, NaOH solution, and water to thereby form an integral mixture of pulp with oxygen at a second consistency, thickening the integral mixture to return it to generally its first consistency, and repeating the mixing and thickening until pulp of a desired Kappa number (15 or below) is reached. The pulp is then washed and may be subsequently treated to reduce the Kappa number thereof to any desired value. A thickener is used which can thicken pulp at superatomspheric pressures and at a temperature greater than 100.degree. C.

Abstract: Fibrous material is pre-steamed, impregnated with alkali liquor, refined, and then oxygen pulped at a low consistency (about 3 to 8 percent solids) using an alkali liquor which contains boron compounds. The pulping step of the process is carried out in stages with recycle of liquor to preceding stages after it has been reoxygenated. By recycling a major portion of the pulping liquor, the actual liquor to fibrous material ratio at each stage of the pulping step is maintained at a relatively high level (12/1 to 30/1) while the effective liquor to fibrous material ratio for the overall process is much lower (4/1 to 8/1). This results in a bright pulp of acceptable strength as well as a high solids content spent liquor which is economically recoverable.

Abstract: A Kraft pulp bleaching process comprising from one to about three treatments with ozone and a final treatment with an alkaline peroxide solution, the treatments being separated by an alkaline extraction, wherein effluent from the bleach treatments is utilized in subsequent bleaching operations or in the chemical recovery system of a Kraft pulping process.

Abstract: A process for delignifying lignocellulosic pulps, which comprises the steps of (a) impregnating a lignocellulosic pulp slurry with a water-soluble manganous salt having a manganous ion concentration of from about 1% to about 10%, by weight of oven-dried pulp; (b) mixing the impregnated pulp slurry with an amount of alkali equal to the stoichiometric quantity of alkali required to precipitate the soluble manganous ion as insoluble manganous hydroxide; (c) aerating the pulp slurry with an oxygen-containing gas without further addition of alkali and in the absence of alkali for a period of time sufficient to oxidize substantially all of the manganous hydroxide to manganic hydroxide; (d) treating the pulp slurry with sufficient sulfuric acid to lower the slurry pH to at least about 3, thus releasing soluble manganic ions to oxidize the pulp lignins; (e) separating the effluent containing manganous ions from the pulp slurry with a non-alkaline wash; and then (f) extracting the oxidized lignins from the pulp slurry

Abstract: By pretreating lignocellulose with an alkaline pretreatment liquor containing anthraquinone or a related compound, prior to alkaline digestion, a higher yield of pulp having a lower lignin content can be produced using less alkali. The pretreatment step is carried out under conditions that ensure survival of at least 50% of the anthraquinone or related compound in the pretreatment liquor, which is separated from the pretreated lignocellulose and reused to pretreat other lignocellulose.

Abstract: Solvent pulping of wood chips or other fibrous plant material is effected using an aqueous solution of a lower aliphatic alcohol in a plurality of batch extraction vessels. The charge in each vessel is heated rapidly to pulping temperature by recirculation of a primary extraction liquor having a relatively high dissolved solids content, and thereafter the charge is subjected to a series of once-through extractions or washes with successively cleaner liquors, including a final extraction or wash with fresh liquor. The extraction liquor from one extraction stage in one vessel is used in another extraction stage in another vessel. Upon completion of the extraction, the liquor is drained from the vessel, the vessel is depressurized to a solvent condenser, and the remaining solvent is steam stripped from the charge and recovered. The used extraction liquor is treated in an alcohol recovery system by flash vaporization, condensation of the solvent vapors, and vacuum stripping of the residual liquor with steam.

Abstract: A method and apparatus for filling a treatment vessel with a fiber material -- liquid mixture. A conventional feeder rotor, having a number of pockets extending therethrough, has each pocket thereof sequentially filled with chips-liquid mixture in a first position from a pretreatment vessel. A portion of the liquid is withdrawn from the pocket, and the pocket rotates to a second position wherein the chips-liquid mixture in the pocket is discharged into a digester by a liquid flow. The pocket then rotates to a third position wherein the liquid in the pocket is discharged by admitting a gas, such as steam, under pressure into the pocket (and the pocket simultaneously filled with gas), and then to a fourth position wherein the gas is allowed to expand and be transported to a pretreatment vessel while the pocket is filled with cooking liquor, and thereby is ready to begin another cycle.

Abstract: 70 To 85% yield semichemical wood pulping may be prepared for mechanical defibration by cooking comminuted hardwood in a continuous digestion vessel with an alkaline cooking solution wherein 50 to 100% as sodium oxide thereof is sodium carbonate. The solution may be formulated from unmodified kraft recovery process green liquor or, if a sulfur free cooking process is desired, the solution may be formulated from soda ash.

Abstract: Apparatus and method for digestion of cellulose material in a continuous digestion process, that do not require screens in the outlet of the digesting zone. Cellulose chips and digesting liquid at relatively low temperature are introduced into a relatively long and thin cylindrical impregnation vessel, having a first diameter. The chips from the impregnation vessel pass into a digestion vessel having a second diameter substantially greater than the first diameter, the outlet for the impregnation zone into the digestion vessel being disposed well into the digestion vessel and below an outlet(s) disposed in the top of the digestion vessel, and form a chips column in the digestion vessel.

Abstract: Process for improving the selectivity of delignification of lignocellulosic material in the presence of oxygen gas and alkali by maintaining a carbon monoxide content in the gas phase within the range from about 1% to about 12% by volume. The carbon monoxide concentration is maintained by withdrawing carbon monoxide and oxygen gas from the delignification, and separating and recycling withdrawn oxygen gas.

Abstract: A slurry of cellulosic material is diluted to a flowable consistency and subjected to a pressure differential on a permeable surface to increase the slurry consistency to a value between the consistency of the diluted slurry and the consistency of the slurry prior to dilution thereby forming a mat of cellulosic material on the permeable surface. The liquid and solids which pass through the permeable surface as a result of the pressure differential are recycled for use as slurry diluent, and to the mat of cellulosic material, while the mat remains on the permeable surface and subject to the pressure differential, is countercurrently applied, in a plurality of treatment stages, a treating liquid, such as a wash liquid, including application of a fresh treating liquid to said mat in the last stage of said treatment stages, whereby the treating liquid displaces at least a portion of liquid present in said mat from said mat and through the permeable surface in each treatment stage.

Abstract: A process for preparing pulp in a closed system by pre-cooking fibrous raw material in an alkaline aqueous solution of sodium carbonate or a mixture of sodium carbonate and sodium bicarbonate as the only alkaline ingredients at 90.degree.-190.degree. C, defibrating the pre-cooked material, pulping the defibrated material in an alkaline aqueous solution of sodium carbonate or a mixture of sodium carbonate and sodium bicarbonate as the only alkaline ingredients in a pressurized vessel at 90.degree.-170.degree. C in the presence of an oxygen-containing gas, subjecting waste liquor discharged from the pre-cooking and pulping steps to wet combustion to recover an alkaline aqueous substance and recycling the alkaline aqueous substance resulting from combustion to the pre-cooking and/or pulping steps.

Abstract: A method and apparatus for filling a treatment vessel, such as a digestor, with fiber material and liquid. A chips-liquid mixture from a pretreatment vessel is fed through a conventional feeding valve to a treatment vessel while the chips-liquid mixture is being acted on by other means in the feeding valve. The feeding valve includes a rotor having a number of pockets extending therethrough, and a plurality of inlets and outlets arranged around the periphery of the valve for communication with the pockets thereof. In a first position of the valve chips-liquid mixture is fed into a pocket, and a portion of the liquid is strained off, then the valve rotates to a second position wherein a quantity of the liquid is displaced by gas or steam while the chips are maintained in the pocket, and then the valve rotates to a third position wherein the chips in the pocket are discharged into the treatment vessel.

Abstract: A process for the preparation of a cellulose pulp by mechanically freeing wood fibers in a grinder to form a fibrous pulp and bleaching the fibrous pulp with a peroxide-containing bleaching agent, as the only bleaching agent, in a peroxide bleaching stage, the mechanical freeing of the fibers being carried out in the presence of a spent liquor from the peroxide bleaching stage have a pH of 7 to 9.

Abstract: A slurry of cellulosic material is diluted to a flowable consistency and subjected to a pressure differential on a permeable surface to increase the slurry consistency to a value between the consistency of the diluted slurry and the consistency of th slurry prior to dilution thereby forming a mat of cellulosic material on the permeable surface. The liquid and solids which pass through the permeable surface as a result of the pressure differential are recycled for use as slurry diluent, and to the mat of cellulosic material is applied a treating liquid, such as a washing liquid.

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.