Abstract: A method for use in a batch digesting process is provided which includes the removal of a portion of the hot cooking liquor from the digester prior to the cook creating a liquid-vapor interface in the digester followed by the removal or purging of the vapors disposed above the liquid-vapor interface and the reduction of the pressure in the digester to about the saturation pressure of the hot cooking liquor. The inclusion of these steps in the process helps to eliminate a coating on the pulp fibers which has been found to inhibit the bleachability and runability of the fibers. Accordingly, an apparatus and method for the batch digesting of pulp fibers is provided which provides pulp fibers having improved bleachability and runability characteristics.

Abstract: Novel substantially odor-free polymeric thiol-containing antioxidant compounds suitable for preventing light induced brightness reversion or yellowing of pulps and papers and polymeric materials are described. The novel compounds are based on a polymeric backbone having thiolactate or thioglycolate groups grafted onto the ends thereof and are soluble in water or alcohol.

Abstract: The invention relates to a process for producing polysulphide by means of oxidizing sulphide in spent liquors from kraft cellulose cooking. The process is characterized in that green liquor is firstly enriched in sulphide and then oxidized.

Abstract: Provided is a process for making pulp having the steps of:contacting an undigested cellulosic fiber material with a pretreatment liquid formulated from a mixture comprising alkali metal bicarbonate and alkali metal hydrogen sulfide as reaction components which are dissolved or disbursed in an aqueous liquid, under conditions that:(1) the reaction components react to form H.sub.2 S, CO.sup.2 and alkali metal carbonate in situ;(2) HS.sup.- ions are formed by disassociation of H.sub.2 S and/or by disassociation of alkali metal hydrogen sulfide; and(3) at least a portion of the H.sub.2 S and/or HS.sup.- ions is absorbed or diffused into the undigested cellulosicfiber material to enhance the sulfur content of the undigested cellulosic fiber material,to form a sulfur enhanced, undigested cellulosic fiber material, wherein the pretreatment liquid is substantially free of alkali metal hydroxide; anddigesting the sulfur enhanced, undigested cellulosic fiber material in a digester to form a pulp.

Abstract: A process for bleaching wood pulp is provided comprising subjecting the wood pulp, after brown stock washing, to an oxygen delignification stage, a washing sequence, a first chlorine dioxide bleaching stage, an oxidative extraction stage, at least one final chlorine dioxide bleaching stage and then recycling the filtrate from the oxidative extraction stage countercurrently through the bleaching plant and brown stock washing. Additionally, and quite beneficially, the filtrate from the first chlorine dioxide bleaching stage is also recycled countercurrently through the brown stock washing thereby significantly reducing the environmental impact associated with the manufacture of bleach wood pulp.

Abstract: Method of separating the surface layer from the core of a piece of wood is escribed. In it, the surface of the piece of wood is initially pre-damaged or roughened and the piece of wood thus treated is thereafter soaked in water or an aqueous solution until the moisture of the wood in the surface layer is at least 30%. Thereafter, the piece of wood thus pre-treated is subjected to a steam process with steam at a temperature of 120 .degree. to 160 .degree. C. by which the surface layer to be removed is solubilized to an extent sufficient for removal from the piece of wood in a following step.

Abstract: A process for bleaching wood pulp is provided comprising subjecting the wood pulp, after brown stock washing, to an oxygen delignification stage, a washing sequence, a first chlorine dioxide bleaching stage, an oxidative extraction stage, optionally at least one final chlorine dioxide bleaching stage and then recycling the filtrate from the oxidative extraction stage counter-currently through the bleaching plant and brown stock washing. Additionally, and quite beneficially, the filtrate from the first chlorine dioxide bleaching stage is also recycled counter-currently through the brown stock washing thereby significantly reducing the environmental impact associated with the manufacture of bleach wood pulp.

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: The present invention discloses a process for treating filter rods comprising cellulose acetate tow waste comprising the steps of:a. cutting said filter rods so that fiber of said cellulose acetate have a fiber length of less than about 4 inches; andb. treating said cut filter rods with an aqueous base until at least 5% of acetyl groups on said cellulose acetate has been hydrolyzed.Filter rods treated in this manner are suitable for use in various paper products. The process of the present invention may further include a step for repulping the cut filter rods to repulp any included plugwrap.Modified fiber comprising cellulose acetate wherein at least 5% of acetyl groups on said cellulose acetate have been hydrolyzed, said fiber having a length of less than about 4 inches, are also disclosed.Paper products comprising between about 5 and about 90% of the fiber of claim 21 and paper pulp are also disclosed.

Abstract: Process for bleaching a chemical paper pulp by means of a sequence of treatment stages involving at least one stage with an enzyme and at least one stage with a peroxyacid.

Abstract: A method of recycling sodium-based salts used for digesting wood in a digester during the manufacture of pulp and paper. The method comprises collecting a black liquor from the digester, concentrating the black liquor, and adding a salt to the black liquor in an amount sufficient to reduce the viscosity thereof. Preferred salts are thiocyanate salts. The black liquor is then oxidized to produce a green liquor and a causticizer added to the green liquor to produce a white liquor containing the sodium-based salts to be recycled. The white liquor is then returned to the digester.

Abstract: A method and apparatus for treating wood pulp that includes incompletely washed brownstock, in which the brownstock is treated at a pH range of approximately 7.0 to 9.0 with a hemicellulase enzyme preparation that has a pH optimum below 6.0. Also, a method and apparatus for treating wood pulp containing incompletely washed brownstock in which the brownstock is treated at a pH range of approximately 6.0 to 9.0 with a hemicellulase enzyme preparation that has a pH optimum below 6.0 and that has a low cellulase content such that not more than about 10,000 FPU are added per ton of pulp.

Abstract: A process for delignifying raw cellulose which comprises a preliminary treatment for impregnating raw cellulose with a monopersulphuric acid solution, a successive filtration without washing with recycle of the filtered liquid to the first step, and a treatment, at low temperature and in alkaline solution at a pH higher than 9, of the previously impregnated raw cellulose in order to permit the reaction of the monopersulphuric acid with the lignin contained in the raw cellulose.

Abstract: A method for the recovery of chemical values from spent lignocellulosic pulping liquor salts to produce white liquor of different sulfidities. Preferably, the white liquor is in the form of separate liquid streams, each of which is of a sulfidity that is different from the sulfidity of others of the streams. The method also provides for developing a white liquor stream which is essentially free of sulfide values, but which contains sodium hydroxide. Further, the method provides for recovery of titanium values for recycling.

Abstract: A method for bleaching pulp containing pulp from color dyed waste paper, wherein the method comprises bleaching the pulp with a bleaching chemical, especially sodium hydrosulfite, in the presence of a selected ethoxylated amine.

Abstract: A process is disclosed for maximizing the brightness of wood pulps which have been treated with anionic bleaching agents wherein the brightness is enhanced by the use of selected quaternary ammonium compounds.

Abstract: A refining assisting agent comprising sulfonated chitosan has been provided. With the addition of the sulfonated chitosan according to the present invention, power needed in the refining can be remarkably reduced compared with that needed in the conventional refining. In addition, the refining assisting additive improves paper strength.

Abstract: The present invention is directed to a process for pulping of lignocellulosic materials. In the process, the ligoncellulose material is impregnated with an alkaline liquor. The lignocellulose material is maintained in the alkaline liquor for a period of time sufficient to permit infusion of the alkaline liquor and swelling of the lignocellulose material. The alkaline liquor is then drained from the lignocellulose material and the lignocellulose material may be washed with water, although such washing step is not required. The alkaline impregnated lignocellulose material is then immersed in an acidic oxidizing solution comprising peroxymonosulfate anion. The lignocellulose material is maintained in the oxidizing solution for a time sufficient to oxidize at least some of the lignin of the lignocellulose material. Thereafter, a second alkaline liquor is used to solubilize the oxidized lignin.

Abstract: A process for enhancing pulp washing efficiency is disclosed. An anionic surfactant is added within the washing or pulping operation to enhance the removal of lignin and spent cooking chemicals from pulp.

Abstract: A chemical pulp which contains reactants capable of generating dioxirane within the pulp is produced in a process which comprises mixing a pulp with reactants comprising a carbonyl compound, preferably acetone, and an oxygen donor, preferably monoperoxysulfate, in proportions which produce a water-soluble dioxirane having a molecular diameter of less than 140 angstrom units. Such a pulp bleaching process which employs dioxirane as a bleaching agent is rendered environmentally and economically acceptable by recycling the reactants employed to produce the dioxirane.

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: An article preservation system and method includes an acid-containing article which is contacted with an alkaline substrate material and an artificial atmosphere which is substantially free of gaseous oxygen. The article, alkaline substrate material and artificial atmosphere are hermetically sealed, along with an oxygen-absorbing material, within an interior of a container.

Abstract: A method for enhancing the penetration of cooking liquor into wood chips to form a Kraft pulp which comprises adding to the cooking liquor specific surfactants such as ethoxylated dialkylphenols and ethoxylated alcohols.

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: 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: The present invention is directed to the use of certain ethoxylated compounds to increase the yield of green liquor semi-chemical pulping processes, the compound have the following structures: ##STR1##

Abstract: Sodium sulfide or hydrosulfide is oxidized to produce sodium polysulfide and sodium hydroxide. Under appropriate conditions, the oxidation may be pursued further to convert all the sodium sulfide into sodium thiosulfate. The oxidation is carried out at or above atmospheric pressure in a mixed reactor or in a pipeline reactor, by sparging oxygen or air, in a mixture of white liquor and lime mud particles produced in the recausticizing plant of a kraft mill.

Abstract: Extended delignification of kraft pulp in a pressure diffuser allows a pulp mill with a digester (e.g. continuous digester) to increase its production capacity without building a new line, or to decrease its demand in its bleach plant, or to increase the strength of softwood pulp it produces. Comminuted cellulosic fibrous material is kraft cooked to produce kraft pulp having a blow temperature over about 300.degree. F. The pulp is diffusion treated in the first stage of a pressure diffuser to replace the water around the pulp with delignifying liquor. The liquor has a dissolved lignin concentration of less than 12% (optimally less than about 4%), has an effective alkali concentration of at least 2 gm/l (preferably 8-55 gm/l), and a temperature of at least about 300.degree. F. Treating the pulp with the delignifying liquor significantly reduces the K-number (e.g. on the order of about 5). After extended delignification, the pulp is washed in subsequent stages of the pressure diffuser.

Abstract: An improved wood pulping process for the delignification of wood in a solvent wherein the solvent is a supercritical fluid under supercritical conditons and contains a delignification agent such as sodium hydroxide, sodium sulfide and/or sodium bisulfate.

Abstract: Alkaline pulping (such as Kraft) processes for various lignocellulosic materials, such as coniferous or disiduous wood chips, into pulp is improved by adding relatively small amounts of a digestive additive selected from the group consisting essentially of anionic surfactants, nonionic surfactants, and anionic/nonionic surfactant blends, such as sodium alpha-sulfo methyl laurate, cocodiethanolamide, butyl ethylenoxide-propylenoxide block copolymers, etc. to the alkaline cooking media to obtain pulps having a select Kappa number range with a reduction in pulp material reject percentage, a reduction of H-factor, a reduction of white liquor requirements and a reduction of cooking time period, relative to H-factor, reject percentages, white liquor requirements and digestion periods experienced in similar alkaline digestion processes without the inventive digestive additive.

Abstract: A process for making paper and linerboard, employing certain nonionic surface active agents to increase the yield of kraft pulping. The surface active agents having the structural formula ##STR1## where n is an integer from 8 to 12, and x is a positive integer from 1 to about 100, the surface active agent being present in the cooking liquor in an amount effective to increase the yield of pulp.

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: The present invention is directed to the use of certain ethoxylated compounds to increase the yield of chemical pulping processes, the compound have the following structures: ##STR1## These ethoxylated compounds have molecular weights of from about 500 to about 30,000 the (CH.sub.2 CH.sub.2 O) comprising from about 20 to 80 percent of the compound; and a, b, and c are each at least 1. The compounds are surface active agents which are added to the cooking liquor. The wood chips are cooked from about one-half and ten hours at a temperature of from about 200 and 500 degrees Fahrenhelt in a liquor including sodium hydroxide, sodium sulfide, and the surface active agent. The wood plug would have a reject level of at least 5% when the chips are cooked in the absence of the surface active agent. The process provides a simultaneous reduction in the level of rejects and an increased yield of pulp.

Abstract: A method of treating an aqueous sodium sulfide solution, such as white liquor in kraft pulping systems, for the oxidation of the sulfide with oxygen in the presence of a specific activated carbon catalyst which is (a) a particulate activated carbon catalyst having an average particle diameter of 0.2-4 mm, a pore volume of at least 0.25 cc/g in pores with diameters of not smaller than 100 .ANG. and a pore volume of at least 35% of the total pore volume in pores with diameters of not smaller than 100 .ANG. or (b) a fibrous activated carbon catalyst having a specific surface area of 300-2500 m.sup.2 /g and an outer surface area of 0.1-5 m.sup.2 /g.

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: Inhibition of calcium scale under the extreme temperature conditions found in pulp digesters has been accomplished by employing certain mixtures of polaminopoly(alkylenephosphonic acids) together with nonionic surfactants. Diethylenetriaminepenta(methylenephosphonic acid) together with a polyethoxynonylphenol has been found especially effective for the purpose.

Abstract: Lignocellulosic material is pulped by a process comprising the steps of: introducing a molecular oxygen-containing gas, such as air, into an alkaline sulfide solution containing NaOH, Na.sub.2 S and at least one cyclic organic compound selected from quinone, hydroquinone, 9,10-diketohydroanthracene and 9,10-dihydroxyhydroanthracene compounds, to oxidize at least a portion of Na.sub.2 S; delignifying the lignocellulosic material with an alkaline sulfide cooking liquor containing the oxidized alkaline sulfide solution at an elevated temperature and; then, recovering the resultant pulp from the delignification mixture.

Abstract: A process is provided for reducing carbohydrate losses in the sulphate pulping of wood using sodium hydroxide and sodium sulfide, by pretreating the wood in the presence of water with oxygen gas and nitrogen oxide such as NO.sub.2 and/or NO and/or polymeric oxides and double molecules thereof, for example, N.sub.2 O.sub.4 or N.sub.2 O.sub.3, for from about 3 to about 110 minutes at a temperature within the range from about 25.degree. to about 100.degree. C., the amount of nitrogen oxide charged, calculated as monomers, being within the range from about 0.05 to about 1 kilomole per 1000 kg bone-dry wood, resulting in one or several of the following advantages: an improved yield of pulp, an improved viscosity, and a reduced requirement for bleaching chemicals in any subsequent bleaching stages.

Abstract: A modified batch cooking technique for making sulfate pulp with a high degree of delignification or with a normal degree of delignification but with increased pulp viscosity. This is effected by one or several displacements of the liquor in the digester with liquor of the same temperature as the cooking liquor but with a lower lignin content.

Abstract: A process is provided for preparing cellulose pulp by delignification of lignocellulosic material, which comprises subjecting particulate lignocellulosic material in a pulping zone to the pulping action of a pulping liquor at a temperature at which pulping reactions leading to formation of cellulose pulp proceed, and substances having a molecular weight above about 3500, preferably above about 2000, and preferably above about 1500, are physically separated and removed from the lignocellulosic material and become dispersed in the pulping liquor; in the course of the pulping, withdrawing pulping liquor containing such dispersed substances, and removing such dispersed substances therefrom; and then returning the pulping liquor to the pulping zone.

Abstract: A method and apparatus are provided for the treatment of comminuted cellulosic fibrous material to effect prehydrolysis, and then subsequently kraft digestion, thereof, to produce paper pulp. The material is steamed, entrained in liquid to form a suspension, and transferred by a high pressure feeder in a first circulation loop to the top of a first vertical vessel. At the top of the vessel, a liquid/solids separator is provided, and the liquid withdrawn from the top of the first vessel into the return conduit of the first circulation loop includes recoverable hydrolysate (which contains hemicellulose, sugars, and the like). In the first vessel, countercurrent acid hydrolysis takes place in the top of the vessel, and a countercurrent wash is effected in the bottom of the vessel. A part of the liquid in the return conduit of the first circulatory loop is diverted to one or more flash tanks, to produce steam and a liquid with a high concentration of hydrolysate.

Abstract: This invention relates to microbicidal/microbistatic compositions for industrial use which comprise 4,5-dichloro-1,2-dithiol-3-one and a haloacetic acid ester and an industrial method of killing and/or inhibiting microbes by using the aforementioned compositions.

Abstract: A method of introducing anthraquinone into the kraft pulping process for the delignification of lignocellulosic material by dissolving or homogeneously dispersing the anthraquinone in a mixture of from about 10% to about 50% white kraft pulping liquor and, correspondingly, from about 90% to about 50% black kraft pulping liquor and then blending this solution with the white liquor feed into the pulping digesters.

Abstract: A process of producing cooking liquor for addition to a digester for enhancement of the yield derived from kraft pulping of wood chips in which a portion of the black liquor is treated with lime under certain conditions and then reused as cooking liquor. The causticizing of the black liquor results in the generation of polysulfide ions and allows, through the formation of calcium-organo complexes, for the carryover of soluble calcium with the black liquor. The presence of calcium ions synergistically enhances the effectiveness of polysulfide such that the use of the new cooking liquor results in pulp yield increases of several percentage points for the same lignin content when compared to conventional kraft pulping.

Abstract: Lignocellulosic material is pulped with an alkaline sulfide cooking liquor which is characterized by containing a combination of a delignification-accelerating additive consisting of a quinone compound, hydroquinone compound, 9,10-diketohydroanthracene compound or 9,10-dihydroxyhydroanthracene compound, and a reducing additive consisting of a sulfite, hydrogen sulfite, thiosulfate or formate.

Abstract: Process for cooking lignocellulosic materials by heating the said materials in a cooking solution containing caustic soda with or without an alkali metal sulphide, in which the solution used contains about 0.01% to 10%, preferably 0.05% to 2%, by weight of 1,2,3,4-tetrahydro-9,10-anthracenediol based on the weight of the dry lignocellulosic material.

Abstract: A method for produce both kraft pulp and alcohol from hardwood chips or the like. The chips are subjected to mild acid prehydrolysis following by mild caustic pre-extraction. The withdrawn hydrolysate has insufficient furfural to inhibit microorganism growth, and both the hexose and pentose sugars in the hydrolysate are fermented to ultimately produce ethanol, butanol, or the like. The chips - after caustic pre-extraction - are subjected to a sulphate cook, and wash, and the resultant pulp is kraft pulp and even has viscosity and tear strength characteristics more desirable than that of conventional kraft pulp. The pulp can be subjected to oxygen delignification, and achieve a higher K number in fewer subsequent bleaching stages than conventional kraft pulp.

Abstract: An improvement in a method for producing paper is disclosed. The paper-producing method involves the steps of preparing a slurry of high lignin content having a predetermined freeness and containing from 1 to 20 percent by weight of fibers, refining the slurry to enable the production therefrom of paper having predetermined properties, forming a web from the slurry and drying the web. The improvement involves treating the high lignin content slurry, prior to the refining step, with a sodium, potassium or lithium alkaline sulfite/sulfide/carbonate solution at atmospheric pressure at a temperature of at least 60.degree. C. and at a pH of at least 10 for from 10 to 60 minutes. The amount of the sulfite/sulfide/carbonate solution should be sufficient that the treatment increases the strength of paper made at the same degree of freeness. The slurry should be one in which at least 50 percent of the fibers are softwood fibers and containing not more than 3.0 percent of residual cooking chemicals.

Abstract: A method is provided for selectively defiberizing and delignifying lignocellulose employing a novel alkaline pulping system. The subject pulping system includes a pulping liquor comprising water, a water-miscible organic reagent, and a sulfide or bisulfide compound selected from the group consisting of alkali metal sulfides and bisulfides, ammonium sulfide and ammonium bisulfide. Extremely high pulp yields as compared to kraft pulping are provided by employing the method and system of this invention.

Abstract: A process for recovering cellulose using sulfuric acid and utilizing the recovered cellulose by hydrolysis to yield glucose. Cellulosic raw materials are hydrolyzed by dilute sulfuric acid to remove hemicellulose, after which the solid residue is separated and is treated with concentrated sulfuric acid to dissolve cellulose contained therein. After blending and mixing of the residue in the concentrated sulfuric acid under mild reaction conditions, cellulose is reprecipitated by addition of water or an organic solvent such as methanol. The recovered cellulose can then be hydrolyzed by cellulose enzymes and/or dilute acids to provide a high yield of glucose. High level recovery and reconcentration of the sulfuric acid is also disclosed.