Abstract: Chemical species (e.g., metaborate, carbonate, hydroxide and sulfide) in a boron-containing alkaline wood pulping liquor sample are determined quantitatively by (i) subjecting a first aliquot portion of the sample to a primary acid titration analysis to derive multiple equivalence points at different respective pH values; (ii) subjecting a second aliquot portion of the sample to an analysis to determine the quantitative presence of boron or sulfide ions therein, and then (iii) determining the quantitative presence in the sample of at least one of the chemical species. Wood pulping parameters may thus be determined on the basis of the quantitative presence of the chemical species to assist in process and/or quality control of the wood pulping operation.

Abstract: A process for bleaching high bulk cellulosic fiber and producing a durable elevated curl index includes: (a) concurrently bleaching, heat treating and convolving cellulosic fiber pulp at elevated temperature and pressure at high consistency generally under conditions selected so as to preclude substantial fibrillation and attendant paper strength and fiber bonding development; and (b) recovering the pulp wherein the length weighted curl index of the treated fiber is at least about 20% higher than the length weighted curl index of the fiber prior to the heat treatment and convolving thereof. Preferably, the curl imparted to the fiber persists upon treatment for 30 minutes in a laboratory disintegrator at 3000 rpm at 1% consistency at a temperature of 125° F. Moreover, the curl may be imparted to the fiber in a disk refiner at very short residence times, on the order of several seconds or less.

Abstract: A method of improving the brightness of calcium carbonate filled paper. The filled paper is dried and then bleached with an aqueous solution of a bleaching agent. The process may be used on all grades of paper that contain filler and is particularly useful in the bleaching of low brightness grade papers that are produced from mechanical pulp that contain calcium carbonate.

Abstract: The present invention relates to a method for bleaching mechanical and chemithermomechanical pulp including that an advancing pulp suspension obtained after that the fibres are laid free is prebleached by adding reductive bleaching agent to the pulp suspension in a location just after the fibres are laid free and that the bleaching is carried out under given conditions in the form of high temperature and minimized oxygen access in respect of said adding location and immediately downstream of said location, characterized in, that the in the described manner prebleached pulp is subjected to at least one further bleaching treatment including that the pulp is bleached with an oxidizing bleaching agent, preferably peroxide bleaching agent, reinforced with borohydride.

Abstract: In a process for extracting cellulose from fibrous materials such as wood, the fibrous materials are reacted with a chemical disintegration solution in the presence of organosilicic compounds.

Abstract: A novel process for bleaching cellulosic pulp is disclosed which provides improvements in pulp brightness and delignification without negatively impacting physical properties of the pulp. Specifically, a process is disclosed in which kraft pulp is treated with at least one of each of an oxidizing agent, an alkaline agent, and a metal substituted xerogel in a bleaching stage to improve brightness and delignification of softwood, hardwood, or recycled pulp. In a preferred embodiment, a process is disclosed which uses at least one metal substituted xerogel as a catalyst in an alkaline peroxide bleaching stage to improve kraft pulp brightness and delignification. Pulps bleached according to the process of the present invention are also disclosed.

Abstract: Shear stable aqueous emulsion of amino modified siloxanes may be made by the addition of a mono acid to the emulsion. These compositions may include acids such as (a) hydroxy carboxylic acids; (b) amino dicarboxylic acids; (c) amic acids; (d) monoesters of dicarboxylic acids; (e) monoesters of di-inorganic acids; and (f) diesters of tri-inorganic acids.

Abstract: A process for final bleaching cellulose-containing pulp which has been subjected to previous bleaching with a peroxide compound. The process involves the sequential steps of exposing the pulp to an amount of a reducing agent in order to eliminate residual peroxide compound from the pulp and then final bleaching the pulp by exposing the pulp to an amount of formamidine sulfinic acid.

Abstract: A process for delignification and bleaching of chemically digested lignocellulose-containing pulp. In a first embodiment, the pulp is acid treated at a pH of between about 1 and about 6, whereupon a water-soluble compound containing an alkaline earth metal is added at a pH of between about 1 and about 7 before the pulp is treated with a chlorine-free bleaching agent. In a second embodiment, the acid and alkaline earth metal treatments are carried out in a single step. The chlorine-free bleaching agent includes peroxide compounds, ozone, oxygen and sodium dithionite in an optional sequence or mixture. After the treatment according to the invention, the pulp may be finally bleached to the desired brightness, suitably with a chlorine-free bleaching agent, such as ozone, to completely avoid formation and discharge of AOX.

Abstract: A method is provided for improving causticizing efficiency in the conventional lime recausticization portion of an alkaline pulping process. Such processes are commonly used in the pulping and bleaching of wood and non-wood cellulose fiber materials. The method of this invention comprises reacting an aqueous solution of sodium carbonate with lime to produce sodium hydroxide (causticization) in the presence of borate in order to improve the causticization reaction efficiency. Borate is added in an amount sufficient to provide a boron to sodium (B/Na) molar ratio in the range of between about 0.001:1 and 0.4:1, and preferably in the range of between about 0.01:1 and 0.3:1, which results in an increased causticization efficiency of up to 8% over the reaction efficiency obtained in the absence of borate.

Abstract: A single stage method delignification process for pulps, preferably sulphite pulps. The improvement to conventional oxygen delignification process comprises in situ addition of a reducing agent substantially non-reactive with oxygen. The end result is a pulp having enhanced strength properties and higher viscosity. Sodium borohydride is the preferred reducing agent, and MgO is the preferred alkali source. Similar results can be obtained with a two-stage oxygen delignification wherein the pulp is treated with the reducing agent in the first stage, and then washed and pressed conventionnally before proceeding with the oxygen delignification in a second stage.

Abstract: A method is provided for the use of borates in the recausticization of alkali-containing liquors such as those produced in the chemical and semi-chemical pulping of wood and in the oxidation and bleaching of wood pulp. Sodium hydroxide is regenerated from sodium carbonate-containing smelts in such pulp processes by autocausticization through the addition of limited amounts of borate. Autocausticization may be carried out at boron to carbonate molar ratios below 2:1 and at sodium to boron molar ratios exceeding 3:1, resulting in high reaction efficiency. Partial autocausticization using borate may also be combined with conventional lime recausticization for the regeneration of sodium hydroxide from sodium carbonate-containing smelts.

Abstract: The present invention relates to a device and method for measuring the bleach requirement and bleachability of pulp in a pulp mill. The invention enables pulp mill operators to better control bleach plants. In one aspect, the invention comprises a system and method for rapid bleaching of the pulp, and measuring the rapid bleached brightness and lignin content of the pulp. In another aspect, the invention comprises an optical system for use in practicing embodiments of this invention.

Abstract: A method for the manufacture of bleached cellulose pulp, in conjunction with which lignocellulose material is digested to form cellulose pulp by means of an alkaline digestion liquor, and the cellulose pulp in the form of a suspension is screened, if necessary, and subjected in series to at least oxygen gas delignification/bleaching (O), if required, chlorine dioxide bleaching (D) and bleaching with non chlorine-containing, oxidative bleaching agent (O, P, Z), with the various bleaching stages interspersed with washing and/or reconcentration of the cellulose pulp in at least one stage, characterized in that complexing agents are added to the cellulose pulp in conjunction with the chlorine dioxide bleaching. It is also important for the mol quotient of the cellulose pulp for magnesium/manganese, during bleaching with a non chlorine-containing, oxidative bleaching agent, to be maintained at or brought to a value exceeding 20, and preferably exceeding 40.

Abstract: A process for the delignification of a chemical pulp, such as a sulfate or sulfite pulp, in which process the pulp is treated with a peroxide and/or a peracid in the presence of an activating Ti-, V- or Cr-group transition metal, such as molybdenum, vanadium or tungsten. A compound containing at least one heteroatom, such as Si, P or B, which is capable of forming a heteropolyacid with the activating transition metal, is added to the pulp. The feeding of the activating transition metal and the heteroatom into the pulp may take place in one and the same alkaline solution, for example introduced into the solution or in the form of a compound of the silicomolybdenic acid type, formed in the solution. The peroxide and/or peracid treatment may constitute part of the bleaching sequence, which contains as potential other treatment steps, for example, a treatment with oxygen and a chelation for the removal of heavy metals such as iron, manganese and/or copper.

Abstract: Enhanced removal of lignin and other extractives in a pulping process is achieved by contacting wood chips and the like with a liquid mixture comprised of white liquor and aminoalkoxylsilane and optionally, one or more nonionic and/or anionic surfactants.

Abstract: The efficiency by which pulp cooking liquor components penetrate the wood and enable lignin and resins to be removed from the cellulosic materials is increased by contacting wood chips and the like with a liquid mixture comprised of white liquor containing at least one surfactant selected from the group consisting of a polymethylalkylsiloxane; a co- and terpolymer of silicone and a polyhydric alcohol; an alkoxylated aryl phosphate; an alkoxylated branched alkyl phosphate; an alkoxylated branched alcohol; an alkyl polyglycoside, an alkoxylated alkyl polyglycoside; a mixture of alkali metal salts of alkyl aromatic sulfate, a sulfosuccinate and a silicone; and combinations thereof; for a residence time effective to extract resinous components without substantial degradation of cellulose and thereafter heating at least a portion of the resulting mixture and wood chips.

Abstract: A process of dignifying lignocellulosic pulp with oxygen followed by treatment of the delignified pulp with a chelating agent, followed by washing, followed by treatment with hydrogen peroxide at an alkaline pH in the presence of an alkali metal silicate at a temperature greater than 100.degree. C. and a pressure greater than 1.5 times the saturated vapor pressure.

Abstract: The efficiency by which pulp cooking liquor components penetrate the wood and enable lignin and resins to be removed from the cellulosic materials is increased by contacting wood chips and the like with a liquid mixture comprised of white liquor containing at least one surfactant selected from the group consisting of a polymethylalkylsiloxane; a co- and terpolymer of silicone and a polyhydric alcohol; an alkoxylated aryl phosphate; an alkoxylated branched alkyl phosphate; an alkoxylated branched alcohol; an alkyl polyglycoside, an alkoxylated alkyl polyglycoside; a mixture of alkali metal salts of alkyl aromatic sulfate, a sulfosuccinate and a silicone; and combinations thereof; for a residence time effective to extract resinous components without substantial degradation of cellulose and thereafter heating at least a portion of the resulting mixture and wood chips.

Abstract: A process for the bleaching of pulp comprising the step of bleaching the pulp with hydrogen peroxide and an effective amount of at least one biodegradable 1-aminoalkane-1,1-diphosphonate chelating agent to enhance the bleaching of the pulp, is disclosed. Also disclosed is the use of a 1-aminoalkane-1,1-diphosphonate to enhance the bleaching of pulp with hydrogen peroxide, as well as the pretreatment of pulp with a 1-aminoalkane-1,1-diphosphonate prior to the step of bleaching with hydrogen peroxide. Finally, the deinking of pulp in the presence of 1-aminoalkane-1,1-diphosphonate is also disclosed.

Abstract: A process for bleaching high-yield (mechanical or chemi-mechanical) pulps to high brightnesses and low yellownesses (b*) in a single treatment employs di-oxygen gas (O.sub.2), alkaline agent and a borohydride. The combined treatment gives brightnesses comparable with those achieved with stabilized alkaline hydrogen peroxide. By comparison the reaction of di-oxygen and alkali alone darkens high-yield pulps; and treatment with alkaline borohydride in the absence of added di-oxygen bleaches to give only about half the brightness gained if di-oxygen is added. The bleaching may possibly occur through the conversion of di-oxygen molecules (O.sub.2) to hydroperoxide ions (HOO-) utilizing ionized phenolic groups or hydroquinones in the lignin. The hydroperoxide ions are thus generated in situ in the lignin and can destroy colored lignin chromophores. Without the addition of borohydride the lignin phenolic groups would be irreversibly oxidized.

Abstract: Paper pulp, especially recycled paper pulp which has been deinked, is bleached in a synergistic two-stage process first with sodium bisulfite and then with sodium borohydride. The borohydride is preferably added in an aqueous mixture with sodium hydroxide. A weak acid such as acetic acid may be added to the pulp to advance further the brightness gain.

Abstract: Process for improving the selectivity of the delignification of a chemical paper pulp by employing a peroxyacid, in which the unbleached pulp originating from the cooking operation is treated with an aqueous solution of this organic peroxyacid in the presence of at least one stabilizer selected from phosphonic acids and their salts.

Abstract: Process for preserving the mechanical strength properties of a chemical paper pulp, comprising two treatment stages by means of a peroxidic reagent, with the first stage in an acidic medium and the second stage in an alkaline medium, according to which a treatment by means of a reducing compound is interposed between the two stages.

Abstract: A method for inhibiting the formation, deposition, and adherency of scale-forming salts, including calcium sulfite, in process waters. The method is particularly suited for use in pulp mill lime kiln flue gas scrubber systems and multi-effect evaporators. Additionally, the method is effective at high pH and high calcium sulfite saturation levels.

Abstract: A scale deposit inhibitor and a method for continuously controlling scale deposition applicable to a digester and its peripheral equipment used in kraft pulp manufacture are disclosed, the scale deposit inhibitor comprising a maleic acid-acrylic acid-hypophosphorous acid terpolymer having a maleic acid unit to acrylic acid unit molar ratio of 1:4 to 4:1, a hypophosphorous acid unit content of 1 to 12 mol %, and a weight average molecular weight of 500 to 10000. The scale deposit inhibitor is added to a cooking liquor in a concentration of 0.01 to 10 ppm per ppm of a calcium ion in the cooking liquor.

Abstract: Deinked paper pulp is subjected to bleaching with sulfite or bisulfite ions and a reducing agent, preferably sodium bisulfite and sodium borohydride in aqueous alkaline solution. To assist the removal of ink particles, steam is bubbled through the pulp causing the ink particles to rise to the surface as a black foam which can be continuously removed.

Abstract: A method of bleaching a chemical pulp by adjusting the pH of the pulp to 1.5-3.5, chelating the pulp and then treating the pulp in an N stage with nitric oxide (NO) in the amount of at least 1.5% by weight of the oven dried pulp at a consistency of between 30 and 55% and further treating the pulp in a Z stage with ozone to produce a bleach pulp having a higher viscosity for a given permanganate number compared with a similar pulp bleached without using the N stage.

Abstract: A process for preparing chemithermomechanical pulp comprising subjecting a lignocellulosic substance from which said pulp is to be formed to the simultaneous action of a sulfite and a reducing agent that is more electronegative than the sulfite ion during a nondestructive cooking operation at a temperature of about 100.degree. C. or above under saturated steam pressure; said simultaneous action taking place at an initial pH of between 7 and 12.5.

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: A process is disclosed for bleaching wood pulp, cellulose or used paper by treatment the fibre material to be bleached before the bleaching steps with a natural or synthetic zeolite or a layer lattice silicate and an easily decomposable organic complex forming agent, e.g. citric acid.

Abstract: A refining process for paper pulp in which colloidal silica sol is mixed with the paper pulp to be refined. The addition of the colloidal silica sol reduces the time necessary to refine the pulp to a predetermined freeness value compared to refining in the absence of the colloidal silica sol.

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 treating paper to prevent discoloration when exposed to light which comprises adding 1% to 10% by weight of hypophosphorous acid or its salt based on the paper at any stage during or after paper making and maintaining said hypophosphorous acid or its salt therein. The invention also provides paper which contains hypophosphorous acid or its salt to prevent discoloration when exposed to light.

Abstract: A sodium borohydride/sodium hydroxide solution for dithionite generation contains sufficient levels of diethylene triamine pentaacetic acid to chelate metals in the dithionate generation process and also in a pulp bleaching process.

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 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 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 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: 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 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: A multistage process for bleaching high-yield and ultra high-yield pulps is described whereby the pulp is treated sequentially with a peroxygen compound, a reducing compound and a final peroxygen compound to achieve higher brightness levels.

Abstract: A process for the oxidative or reductive bleaching of wood pulp, especially in the presence of heavy metal salts, in which a complex former combination containing at least one phosphonic acid, at least one polyhydroxycarboxylic acid and at least one phosphate or salts thereof is added to a wood pulp slurry in an amount of from 0.5 to 50%, based on the dry mass of the wood pulp, and subsequent bleaching is carried out in the presence of a reducing agent. Also provided is a complex former combination for use in the oxidative or reductive bleaching of wood pulp, comprising at least one phosphonic acid, at least one polyhydroxycarboxylic acid and at least one phosphate or salts thereof.

Abstract: A two-stage hydrogen peroxide bleaching treatment of chemical pulp at a temperature of about 90.degree.-100.degree. C. comprising subjecting said pulp in a first stage to hydrogen peroxide and to at least about 3 grams/1 of bath of a metal ion sequestering agent selected from nitrogen containing sequestering agents or agents derived from polyphosphoric or polyphosphonic acids at a pH of 8.5 to 9.5 so that hydrogen peroxide of about 0.3 to 2.5 wt. % relative to dry pulp weight is consumed, and subjecting said pulp in a second stage to hydrogen peroxide and to at least about 3.times.10.sup.-3 gram-atoms per 100 grams of dry pulp of magnesium in the form of magnesium hydroxide and a pH of at least about 11 so that about 2 to 5 weight % of hydrogen peroxide per weight of dry pulp is consumed during the two stages.

Abstract: Bleaching of wood pulp is improved by the combination of a pretreatment of the pulp with a polyaminocarboxylic acid, e.g. ethylenediaminetetraacetic acid, prior to bleaching with an alkaline aqueous peroxide solution containing a stabilizing amount of an aminophosphonic acid derivative together with a polymer of an unsaturated carboxylic acid or amide or an alkylsulfonic acid substituted amide.

Abstract: The extent of delignification of chemical pulps by oxygen-containing chemicals, preferably hydrogen peroxide, is enhanced by demethylating the pulp prior to such oxidative delignification, to a degree of demethylation of at least about 30%, preferably at least about 50%. Demethylation may be achieved by chemical treatment of the already-formed pulp or by modification to the pulping process to result in demethylated pulp.