Abstract: Kraft pulp is bleached to a brightness of about 90 CPPA or greater, without the use of chlorinated organic compounds that has commercially acceptable strength properties. During production of the kraft pulp it is subjected to extended delignification, by adding kraft white liquor to a first recirculation loop in the digester, and/or a second, wash, recirculation loop in the digester; or by conventional pulping followed by two oxygen stages, with washing between the stages. The extended delignification pulp is then subjected to ozone bleaching, with an ozone dosage of less than 1.0% (preferably less than about 0.5%). The ozone bleaching sequence may be a (ZE)P(ZE)P sequence.

Abstract: In a process for chlorine-free bleaching of cellulose with an .alpha.-cellulose content of more than 90%, preferably from boiled cotton linters, more than 75% whiteness is achieved in a single-stage process using oxygen. The bleaching is conducted using the oxygen obtained by disproportionation of peroxo compounds in the pH range from 6 to 13 and with the bleaching time, depending on the bleaching temperature of 35.degree. C. to 15.degree. C., being between 15 and 150 minutes.

Abstract: A process for the comminution, in particular defibrillation, and reaction of fibrous materials having a high dry solids content with the addition of a circulating medium, preferably a carrier gas and/or reaction agent, as well as optionally of chemicals. The invention is mainly characterized in that the circulating medium is recycled after leaving the comminuting device, by changing its temperature, and is then recycled to the comminuting device. Another embodiment of the invention is characterized in that the fibrous materials and liquid reaction agent are separated from the carrier gas and reaction agent vapors, which are then recycled back to comminuting device. A plant for carrying out this process is mainly characterized in that the comminuting device and route for recycling and treatment of the circulating medium form a closed system.

Abstract: The invention relates to a process for bleaching chemically delignified lignocellulose-containing pulp, to render more efficient a peroxide-containing treatment stage, by treating the pulp with a complexing agent before the peroxide step, so that the trace metal profile of the pulp is altered by the treatment with the complexing agent, in the absence of sulphite, at a pH in the range from 3.1 up to 9.0 and at a temperature in the range from 10.degree. C. up to 100.degree. C., whereupon, in a subsequent step, the treatment with a peroxide-containing substance is carried out at a pH in the range from 7 up to 13, said two-step treatment being carried out at an optional position in the bleaching sequence applied to the pulp.

Abstract: A process for the continuous mass-production of chemical pulp from cellulose raw materials without adversely affecting the environment involves digesting the cellulose raw materials at 130.degree. to 200.degree. C. with a cooking liquor containing an alkali, hydrogen peroxide, a chelating agent, an anthraquinone and water. A pulp waste liquor and unbleached pulp are obtained by subjecting the digested cellulose raw materials to solid-liquid separation. The pulp waste liquor is concentrated and burned to obtain an alkali metal carbonate. Calcium oxide is added, if necessary, to the aqueous solution of sodium or/and potassium carbonate for causticization, and hydrogen peroxide, a chelating agent, and an anthraquinone are added to the alkali solution to regenerate the cooking liquor.

Abstract: Bleached chemithermomechanical wood pulp having a high degree of whiteness is economically prepared by mechanically disintegrating and chemically digesting lignocellulosic material with sulfite at a temperature of at least 100.degree.C. under saturated water vapor pressure and thereafter bleaching the pulp thus treated with hydrogen peroxide in an alkaline medium, and wherein no solids or liquids are removed from the pulp from the outset of treatment through completion of the bleaching step.

Abstract: High-yield lignocellulosic wood pulps are bleached by (i) first pretreating such pulp with a complexing agent for metal ions and next washing the pretreated pulp, and then (ii) bleaching such pretreated/washed pulp with an initial amount of hydrogen peroxide in an alkaline medium, including adding a supplementary bleaching amount of hydrogen peroxide and a supplementary amount of an alkaline agent to the pulp over the course of the bleaching step (ii) without interrupting same, at a point in time when from 60% to 85% of the initial amount of hydrogen peroxide has been consumed, and such supplementary amount of hydrogen peroxide being equal to or less than the initial amount thereof.

Abstract: A method of effecting a reaction between oxygen and an organic substance comprising the stages of:a. forming a reaction mixture comprising an N-alkylpyrrolidinone, at least one organic substance capable of reaction with oxygen and a hydroperoxide decomposition catalytically effective amount of a transition metal oxidation catalyst under a partial pressure of oxygen of at least about 16 psig, the molar ratio of organic substance to N-alkylpyrrolidinone being at least about 1:100;b. subjecting the reaction mixture to conditions such that an oxidation reaction occurs, whereby:(1) at least a portion of the N-alkylpyrrolidinone is oxidized, in situ, to the corresponding hydroperoxide;(2) the hydroperoxide is subsequently decomposed by the catalytic action of the transition metal oxidation catalyst to the corresponding N-alkylsuccinimide, the decomposition resulting in the production of active oxygen which reacts with the organic substance;c.

Abstract: A process for producing bleached pulp from a fibrous plant material (e.g., wood), wherein the material is contacted with an alcohol solvent in a pulping zone to extract lignin from the fibrous plant material. The resulting pulp is then treated with a hydroperoxide or peroxide bleaching agent in a bleaching zone to form bleached pulp. Alcohol formed from the hydroperoxide or peroxide during the bleaching process may be recycled to the pulping zone. A preferred alcohol is tert-butyl alcohol, while a preferred hydroperoxide is tert-butyl hydroperoxide.

Abstract: A process is provided for peroxygen bleaching of high yield pulp in which sodium carbonate replaces sodium hydroxide and sodium silicate. The process employs a chelating agent as a substitute for the silicate normally required so that the process can operate as a closed cycle system.

Abstract: Delignification and bleaching of lignocellulosic material is enhanced after the pulp has been treated with peroxomonosulfuric acid.

Abstract: A method of brightening mechanical pulps by chelating and thickening to reduce the manganese content of the pulp to less than 30 parts per million and copper content less than 1 parts per million by adding ions preferably magnesium ions as magnesium sulphate MgSO.sub.4 in the amount of 400 to 3,000 ppm Mg ions retained by the pulp based on the oven dry weight of the pulp and thereafter applying a bleaching liquor composed of peroxide as hydrogen peroxide and an alkali as sodium hydroxide having a ratio of alkali to peroxide of between 1--1 and 2-1 in an amount to apply between 1 to 8 percent peroxide based on the oven dry weight of the pulp and containing no added sodium silicate. Preferably the bleaching liquor will contain magnesium sulphate in the amount of about 0.001 to 0.1% based on the oven dry weight of the pulp.

Abstract: A process for delignifying and bleaching a lignocellulosic pulp without the use of elemental chlorine by partially delignifying the pulp to a K No. of about 10 or less and a viscosity of greater than about 13 cps; and further delignifying the partially delignified pulp with an effective amount of ozone for a sufficient time to obtain a substantially delignified pulp having a K No. of about 5 or less, a viscosity of greater than about 10, and a GE brightness of at least about 50%. The substantially delignified pulp may be brightened by the addition of a bleaching agent such as chlorine dioxide or a peroxide to obtain a final product having a GE brightness of at least about 65%, preferably above 70% to as high as 90%. Because of the absence of elemental chlorine in this sequence, filtrate from all stages but the chlorine dioxide stage (if used) can be recovered without sewering. Major environmental improvements are thus achieved.

Abstract: The removal of manganese from pulp is enhanced by supplementing the treatment with a chelating agent by the addition of at least 500 ppm of magnesium ions prior to thickening of the pulp thereby to reduce the manganese content of the thickened pulp significantly more than the content would be reduced by the treatment with the chelating agent without the magnesium ions.

Abstract: High-yield lignocellulosic wood pulps are bleached by treating same with an effective bleaching amount of hydrogen peroxide in an alkaline treatment medium, including adjusting the alkalinity of such pulp by adding a supplementary amount of alkaline agent thereto at that point in time when the amount of hydrogen peroxide consumed ranges from 40% to 75% of the effective amount thereof.

Abstract: A process for delignifying and bleaching a lignocellulosic pulp without the use of elemental chlorine by partially delignifying the pulp to a K No. of about 10 or less and a viscosity of greater than about 13 cps; and further delignifying the partially delignified pulp with an effective amount of ozone for a sufficient time to obtain a substantially delignified pulp having a K No. of about 5 or less, a viscosity of greater than about 10, and a GE brightness of at least about 50%. The substantially delignified pulp may be brightened by the addition of a bleaching agent such as chlorine dioxide or a peroxide to obtain a final product having a GE brightness of at least about 65%, preferably above 70% to as high as 90%. Because of the absence of elemental chlorine in this sequence, filtrate from all stages but the chlorine dioxide stage ( if used) can be recovered without sewering. Major environmental improvements are thus achieved.

Abstract: A process for delignifying and bleaching a lignocellulosic pulp without the use of elemental chlorine by partially delignifying the pulp to a K No. of about 10 or less and a viscosity of greater than about 13 cps; and further delignifying the partially delignified pulp with an effective amount of ozone for a sufficient time to obtain a substantially delignified pulp having a K No. of about 5 or less, a viscosity of greater than about 10, and a GE brightness of at least about 50%. The substantially delignified pulp may be brightened by the addition of a bleaching agent such as chlorine dioxide or a peroxide to obtain a final product having a GE brightness of at least about 65%, preferably above 70% to as high as 90%. Because of the absence of elemental chlorine in this sequence, filtrate from all stages but the chlorine dioxide stage (if used) can be recovered without sewering. Major environmental improvements are thus achieved.

Abstract: Methods for producing mechanical pulp are disclosed including impregnating softwood chips with water and a complexing agent, refining the impregnated chips in a first refining step including a double-disk refiner, fractionating the refined softwood pulp to produce a reject portion comprising beteen about 15 and 35% of the refined pulp and including an increased concentration of the long and stiff fibers therein, refining the reject portion in second and third refining steps in which the second refining step employs a greater concentration of pulp than does the third refining step, and fractionating the refined pulp.

Abstract: A three-stage bleaching process for dissolving grade pulp utilizes the sequence OP(alkaline)-Z-P and the off gas from the Z-stage is delivered to the alkaline (OP)-stage whose parameters are controlled to fully react all of the oxygen of the off gas. The filtrate or waste water from the Z-stage, at a pH below 3, serves to dilute the alkaline OP-stage pulp before Z-stage bleaching and/or for de-ashing of the P pulp following the P-stage.

Abstract: A composition for alkaline hydrogen peroxide bleaching of mechanical wood pulp which employs a quaternary amine compound, such as (3-chloro-2-hydroxy-propyl) trimethyl ammonium chloride, in the stabilized bleach solution. The brightness of the final paper product made from such bleached pulp shows marked improvement over that in which only chelating agents are employed to improve the brightness according to the known art. The process is useful in both silicate and silicate-free bleach solutions.

Abstract: A process for delignification and bleaching of chemically digested lignocellulose-containing pulp for reduced formation and discharge of halogenated organic compounds, while preserving the pulp quality, where the prebleaching with halogen-containing bleaching agent is replaced by a treatment, in a first step, with the addition of a complexing agent at elevated temperature and at a pH from 3.1 to 9.0, and in a second step, by using a peroxide-containing compound under alkaline conditions, whereupon spent liquor from the final bleaching with halogen-containing compounds is recycled to the first or second step of the halogen-free prebleaching.

Abstract: A process for the manufacture of high-yield pulps bleached with the aid of hydrogen peroxide in alkaline medium, which consists in subjecting the pulp to be bleached successively to:(a) a pretreatment with the aid of a sequestering agent for metal ions, followed by a washing operation,(b) a treatment with sulphite and a reducing agent which is more electronegative than the sulphite ion, which act together and in a medium of initial pH between 7 and 12.5, followed by a washing operation to remove the sulphite ions and the reducing agent, and(c) to a bleaching treatment with the aid of hydrogen peroxide in alkaline medium in the presence of a quantity of silicate of between 0% and 1%.

Abstract: A process for souring chemical or mechanical cellulosic pulp using carbon dioxide to obtain proper acidification of the pulp slurry. The souring is performed after a single or a multistage bleaching sequence ending with sodium hypochlorite, calcium hypochlorite or hydrogen peroxide or the like in a common process for the preparation of paper pulp. The use of CO.sub.2 permits bleaching to continue because CO.sub.2 does not destroy the bleaching residuals remaining from the single or last bleaching stages.

Abstract: A continuous two-stage peroxide bleaching process operated in a single bleach plant for producing a bleached pulp of high brightness, having a second stage bleaching step using a high charge of peroxide followed by a washing stage to recover the residual liquor containing a substantial amount of the applied peroxide. The residual liquor is recycled and used for bleaching in the first stage. Only a portion of the pulp bleached in the first stage is treated in the second stage. Two or more bleached pulp products can be produced simultaneously. The bleached pulp products can be used to form different layers of a multi-layer paper products.

Abstract: Delignification and bleaching of lignocellulosic material is enhanced after the pulp has been treated with peroxomonosulfuric acid. The starting pH of the reaction with peroxomonosulfuric acid is between 7 and 11, and the reaction is continued until a final pH of 3 to 5 obtained. Subsequently the pulp is delignified and bleached with peroxide and/or oxygen.

Abstract: A method for bleaching pulp using an alkaline, peroxide-containing bleaching agent for chemical pulp, mechanical pulp, waste paper and/or mixtures thereof, which optionally contains water glass and/or a complexing agent, contains, as an additive, a silicate ion exchanger which has been modified using an alkali metal carbonate or alkali metal hydrogen carbonate.

Abstract: A method for treating lignin containing pulp, subsequent to being bleached by:a) always treated with at least one chemical, which chemically reduces .alpha.-carbonyl and .gamma.-carbonyl groups in the lignin; and in at least one further step isb) treated with at least one chemical, which will block the phenolic hydroxyl groups of the lignin and/orc) supplied with at least one chemical, which will convert short-wave light quanta to long-wave light quanta.According to a preferred embodiment of the invention cellulose pulp is subjected to all of the above treatment processes, i.e. a)+b)+c) and is washed after the two initial treatment stages. The method solves the problem of yellowing of lignin containing pulps, e.g. high yield pulp.

Abstract: The present invention provides a process for bleaching and delignifying cellulose-containing products with peroxides and/or oxygen and/or ozone, wherein there is additionally used 0.01 to 2.5% by weight of cyanamide and/or cyanamide salts, referred to the dry weight of the cellulose.

Abstract: A process for alkaline hydrogen peroxide bleaching of mechanical wood pulp which employs a quaternary amine compound, such as (3-chloro-2-hydroxypropyl)trimethyl ammonium chloride, in the stabilized bleach solution. The brightness of the final paper product made from such bleached pulp shows marked improvement over that in which only chelating agents are employed to improve the brightness according to the known art. The process is useful in both silicate and silicate-free bleach solutions.

Abstract: A process is provided for a two-stage oxygen delignification of chemical pulp in which 0.01% to 1% hydrogen peroxide is incorporated into the first and, optionally the second stage. The invention is particularly suitable when the pulp is subsequently bleached with at least one chlorine dioxide stage and at least one hydrogen peroxide stage.

Abstract: A method for the delignification of lignocellulosic materials with acidic aqueous solutions of monoperoxysulfuric acid for the production of cellulosic pulps for use in papermaking and regenerated cellulose products and for use as animal feeds and other products where removal of lignin is required.

Abstract: A method for producing a novel pulp, primarily wood pulp, from chips using pre-treatment with stabilizers and alkaline peroxide prior to mechanical fiberization (refining) to increase the brightness of the resulting fibers and the papermaking strength achievable with the fibers. The novel aspect of the pretreatment prior to refining is that it reuslts in the "in situ" formation within the chips of a stabilizing flock or sol.

Abstract: A synergistic combination of high-shear mechanical disruption and alkali pretreatment in a high solids reaction mixture constitutes a significant improvement in the alkaline peroxide treatment of lignocellulosic materials. The simultaneous application of these conditions greatly reduces the amounts of reagents otherwise required, and also eliminates the waste stream of liquid byproducts. Suitable sources of substrate treatable by this process include nonwoody plant parts, crop residues, and agricultural byproducts. The products of this treatment are nontoxic and characterized by high cellulose availability. These products are thereby useful as carbohydrate sources in ruminant feeds, as microbial feedstocks, and as sources of dietary fiber for humans and other monogastrics.

Abstract: An improved process for delignifying and bleaching nonwoody, lignocellulosic material into products digestible by ruminants and ingestible by humans. The process comprises treating the substrate in an alkaline solution for a period of time, separating the wetted substrate from the slurry and then treating the wetted substrate with an alkaline peroxide solution at an initial pH of 8.5 to 11.0 for a period of time, and separating, washing and drying the product.

Abstract: A process is provided for the bleaching of wood pulp with hydrogen or sodium peroxide. The process includes the steps of adding to a wood pulp a bleach liquor having an effective amount of hydrogen or sodium peroxide bleaching agent and, by weight of the diluted wood pulp, 0.5 to 6% sodium hydroxide, 0 to 5% sodium silicate, 0 to 1%, preferably 0.02 to 0.05%, magnesium sulphate, and a chelating agent in an amount sufficient to sequester heavy metal ions in the pulp, to produce a pulp consistency of 1 to 16% at a temperature in the range of the bleach liquor freezing point to 25.degree. C., uniformly mixing the bleach liquor with the wood pulp, and immediately thickening the diluted wood pulp to a consistency in the range of 20 to 70% for bleaching of the thickened wood pulp.

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: A rapid, single stage process for the bleaching of high yield lignocellulose pulp (mechanical pulp) to enhanced brightness levels with hydrogen peroxide in the presence of magnesium sulphate and sodium silicate, with a substantial reduction in the wasteful, non-bleaching reactions of hydrogen peroxide. The residual hydrogen peroxide liquor may be recycled to a pulping or bleaching process.

Abstract: A process for the separation of the fibres from each other in lignocellulosic (straw, bagasse, wood) composites, and at the same time to dissociate the Lignin and the Xylan in the middle lamella and the primary wall of the lignocellulosic material, to enable a simple non reactive solvent extraction of the middle lamella and primary wall components while substantially retaining the structural integrity of the fibre bundle, sometimes referred to as the S2 layer, which is the strength member of the lignocellulosic fibre. The purpose of this process is to produce a fibre suitable to replace conventional Chemical Thermal Mechanical Pulp, for paper or as a carrier for high absorbency Cellulose in diaper and similar absorbent material applications, and at the same time to recover the chemical components of the middle lamella and the primary wall of the fibre, as co-products in a marketable, chemically reactive form.

Abstract: Chemimechanical pulp is produced from lignocellulosic material in a process in which the material is impregnated in two stages. The material is treated in the first stage with alkaline and, subsequent to passing an intermediate draining and reaction step, in the second stage with a solution that contains peroxide. The quantities of alkali and peroxide charged are fully optional and are independent of one another. The material is then optionally subjected to a further drainage and reaction step, and thereafter pre-heated at a temperature of between 50.degree. C. and 100.degree. C., whereafter the material is refined in one or two stages.The optimal brightness of the processed pulp for a given peroxide consumption is achieved by a balanced division of the peroxide charge between chip impregnation and bleaching.

Abstract: A process is provided for activating cellulose pulp using NO and/or NO.sub.2 plus oxygen gas in the presence of nitric acid, added in an amount within the range from about 0.1 to about 1.0 gmole per kg of water accompanying the cellulose pulp at a temperature within the range from about 40.degree. to about 120.degree. C. for a time at an activating temperature of 40.degree. to 50.degree. C. of from 15 to 180 minutes, at from 50.degree. to 90.degree. C. of from 5 to 120 minutes, and at higher temperatures of from 1 to 10 minutes, followed by washing, and delignifying bleaching in an alkaline medium with or without oxygen gas and/or peroxide.

Abstract: Method of peroxide bleaching of mechanical, thermomechanical and chemi-mechanical pulp wherein the peroxide bleaching is controlled by addition of a known amount of bleaching chemicals in the first stage which amount is allowed to react under defined conditions whereafter the brightness of the pulp after this first stage is used for control of a subsequent stage. In the first stage fresh chemicals, chemicals recirculated from a subsequent bleaching stage or a mixture of these is used. Hydrogen peroxide is the preferred bleaching agent but other peroxides can also be used.

Abstract: An improved process of purifying the product from an alkaline peroxide treatment process for delignifying and bleaching nonwoody lignocellulosic agricultural residues comprising, optionally washing with water, then lowering and maintaining the pH of the substrate at less than about pH 3.0, then washing sufficiently to remove residual chemicals, separating the product from the wash liquid and, optionally, drying the product.

Abstract: An improved process for delignifying and bleaching nonwoody, lignocellulosic material into products digestible by ruminants and ingestible by humans. The process comprises treating the substrate in an alkaline solution for a period of time and adding magnesium ions prior to adding peroxide or, alternatively, adding the magnesium to the peroxide prior to adding the peroxide to the alkaline slurry.

Abstract: A process for the production of a pulp from bast fibers, which includes reacting a mixture of the bast fibers and an aqueous digestion liquid at a temperature of 60.degree.-130.degree. C. The digestion liquid includes (a) hydrogen peroxide or a compound capable of generating hydrogen peroxide in the presence of water, (b) an alkali metal carbonate, and (c) an oxalate.

Abstract: A method for producing novel pulp, primarily wood pulp, from chips using pre-treatment with stabilizers and alkaline peroxide prior to mechanical fiberization (refining) to increase the brightness of the resulting fibers and the papermaking strength achievable with the fibers. The novel aspect of the pre-treatment prior to refining is that it results in the "in situ" formation within the chips of a stabilizing flock or sol.

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: Process for the delignification of cellulosic substances comprising:a first stage of treatment of cellulosic substances with an acida second stage of treatment with hydrogen peroxide in an alkaline mediuma third stage of digestion in the presence of at least one chemical reactant chosen from hydroxides of alkaline or alkaline-earth metals.The process applies to the treatment of wood fragments.

Abstract: Process for the delignification of cellulosic substances comprising:a first stage of treatment of cellulosic substances with an acida second stage of treatment with hydrogen peroxide in an alkaline mediuma third stage of digestion in the presence of at least one chemical reactant chosen from sulphur-containing compounds and oxygen.The process applies to the treatment of wood fragments.

Abstract: A process for bleaching a lignocellulosic matter in the form of a mechanical, thermomechanical, chemicomechanical or chemicothermomechanical papermaking pulp, or of wood chips while being converted into one of these pulp types by processing in a machine consisting essentially of two interpenetrating spiral surfaces wound around parallel shafts driven in synchronous rotation in the same direction inside a barrel which encloses them, and determining between upstream and downstream in the direction of forward travel of the matter a series of zones for drawing and braking the matter, which comprises combining a bleaching treatment using a reducing agent and a bleaching treatment using an oxidizing agent, characterized in that, after pretreatment using at least one metal-complexing or sequestering agent, the lignocellulosic matter undergoes a washing operation with an efficiency greater than 96% before undergoing in succession a bleaching treatment using a reducing agent at a pH of between about 8 and 12, a washin

Abstract: Nonwoody lignocellulosic portions of plant fruits, roots, and tubers, such as sugar beet pulp, citrus pulp, seed hulls, and cereal bran are treated with hydrogen peroxide under alkaline conditions thereby delignifying the materials and rendering the cellulose and hemicellulose highly available for subsequent use. The products are characterized by enhanced water-binding capacity of the cellulose as indicated by high water swellability. The products are also nontoxic and thereby useful as carbohydrate sources in ruminant feeds, as microbial feedstocks, and as sources of dietary fiber for humans and other monogastrics.