Abstract: A process for bleaching chemical pulp for paper manufacturing comprising delignifying and bleaching chemical pulp which has been treated by cooking by simultaneous use of chlorine dioxide, a peroxide, and at least one reaction catalyst selected from the group consisting of oxoacids of elements of Groups IV, V and VI and salts of these acids. Formation of organic chlorine compounds as by-products is suppressed by decreasing the amount of chlorine dioxide used in the ECF bleaching process in the first stage, and thus environmental toxicity in the waste water discharged from the bleaching process is decreased. Chemical pulp having a high degree of brightness is economically produced because increase in the production capacity is not required at all or suppressed to the minimum, and the investment cost is reduced to the minimum when the bleaching with chlorine in the first stage is converted into the bleaching with chlorine dioxide which is an ECF bleaching process.

Abstract: A process for bleaching cellulosic pulp to a G.E. brightness of at least about 75 and a viscosity of at least about 14 wherein the effluent from the bleaching process is of reduced colored matter content and exhibits reduced COD. The process comprises DZD stages without interstage treatment of the pulp other than by an optional water wash.

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: 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: A method of bleaching a pulp at low consistency employs chlorine dioxide and/or chlorine, to partially bleach the pulp. The aqueous partially bleached pulp flows along a sinuous flow path providing a high ratio of flow path of aqueous pulp to length of effective travel of the aqueous pulp. Ozone is introduced to the aqueous pulp at spaced apart locations in the flow path so that a low partial pressure of ozone is established in the flow path which favors chemical oxidation of the lignin and low chemical attack on cellulose. In this way effective bleaching is achieved with reduced use of chlorine or chlorine dioxide and reduced production of chlorinated compounds.

Abstract: Wood pulps are bleached and/or delignified using soybean peroxidase. A protease, xylanase, ligninase, pectin esterase, pectin lyase or manganese peroxidase may also be used simultaneously or as a pretreatment or posttreatment.

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: Method and apparatus for ozone bleaching a medium consistency cellulosic fiber suspension include feeding the fiber suspension and an ozone in carrier gas stream under pressure into a fluidizing mixer; intimately and uniformly mixing the fiber suspension with the ozone to achieve a bleaching reaction; passing the mixture into a first reaction vessel to permit the bleaching reaction to proceed and to consume a major part of the ozone; adding a second bleaching chemical to the mixture; separating the excess ozone and carrier gas from the mixture in a second considerably larger vessel and removing the fiber suspension from the second vessel after the effective second bleaching reaction.

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 method of bleaching chemical pulp in a sequence comprising at least four bleaching steps with final bleaching in a first and a second chlorine dioxide step. Between the chlorine dioxide steps an alkaline extraction is carried out, and washing takes place between the first chlorine dioxide step and extraction. Immediately after said washing step, NaOH is charged in an amount of 4-10 kg/ton pulp. Thereafter an oxidizing agent is admixed in an amount of at maximum 2 kg/ton pulp. After 15-120 seconds an acid is added for terminating the oxidation treatment and for lowering the pH-value, but without effecting a complete neutralization of residual alkaline.

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

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 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 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: An improved process for bleaching cellulosic pulp in a first chlorination stage of a multi-stage bleaching process is provided, which involves an improved process for bleaching cellulosic pulp in a first chlorination stage of a multi-stage bleaching process, comprising: (a) admixing cellulosic pulp with a first chlorine dioxide charge and reacting the cellulosic pulp and said chlorine dioxide for a period of time ranging from about 1 second to about 10 minutes; (b) admixing the cellulosic pulp effluent obtained after step (a) wtih chlorine and chlorine dioxide and reacting the thus-obtained cellulosic pulp for a period of time ranging from 1 second to about 10 minutes; and then (c) admixing the cellulosic pulp effluent obtained after step (b) with a second chlorine dioxide charge and reacting the thus-obtained cellulosic pulp effluent for a period of time ranging from about 1 second to about 10 minutes, wherein the pH of the reaction mixture is maintained throughout the bleaching process at from about 5.

Abstract: The chemical components of lignocellulosic material which have been dissociated by a steam explosion process can be extracted from the mixture of components using a solvent extraction process. The solvents are water, alcohol and a mild caustic in that order, or the alcohol step can be by-passed and only water and caustic are used. The caustic is a stronger solvent and it will extract the alcohol solubles along with the caustic only solubles. The eluant from the these extractions contains a range of lignin derived substances, which have different applications, such as thermoplastic and thermosetting characteristics. This invention describes a method for partitioning these lignin components into reproducible fractions having definable characteristics for particular applications. For instance, many copolymer applications require a thermosetting only fraction of the lignin. Other applications require a thermoplastic only lignin.

Abstract: In the method of chemical pulping of wood including a chlorination stage pulp bleaching step followed by alkaline extraction, a method of reducing the amount of dioxins and furans produced thereby is disclosed wherein the brownstock pulp is first washed with alcohol prior to bleaching.

Abstract: Method and apparatus for reducing contamination in processed pulp and in white water effluent discharged from a pulp dryer or paper making mill. The system includes multiple pulp bleaching and washing stages wherein white water effluent discharge from the dryer or paper making mill is fed to the next-to-last washing stage and fresh water is supplied to the last washing stage.

Abstract: Ozone and chlorine are used to bleach cellulosic fibrous material pulp in the production of kraft pulp for paper and paper products, being applied together in a mixture. When the ozone and chlorine are applied simultaneously it is possible to achieve delignification to a greater extent than is possible utilizing chlorine at any level. The total chlorinated ring compounds in the bleach plant effluent are remarkably reduced utilizing the ozone-chlorine mixture, compared to all chlorine, with resulting decrease in the fish toxicity of the bleach plant effluent. Utilizing an O.sub.3 /Cl.sub.2 E.sub.o D bleaching sequence (only three stages) it is possible to obtain pulp with 90 TAPPI Absolute, or greater, brightness.

Abstract: A chemical pulping process is disclosed wherein wood chips are partially defiberized such that the fibers in the chips are substantially separated from one another but sufficient interfiber bonding is maintained to preserve chip integrity and thereby provide chips having an open porous fibrous network; and the chips are subjected to chemical pulping at an elevated temperature to remove a majority of the lignin in the chips.

Abstract: Chlorine gas is directly introduced, without the necessity of adding water with the gas, into a paper pulp slurry (i.e. comminuted cellulosic fibrous material) having a consistency of between about 6-15 percent. The gas is added to the inlet of a fluidizing mixer at the point where the slurry enters the fluidizing mixer, and is intimately mixed with the pulp by the mixer. The flow of the chlorine gas is in a flow controlled pathway, which is split into at least two flows so as to increase the total gas volume added to the pulp stock and obtain enhanced mixing. Each of the split flows is introduced to the inlet of a fluidizing mixer. The split flow addition of chlorine gas into two or more mixer inlets also may be practiced for low consistency pulp (e.g. pulp having a consistency of between about 1-5 percent).

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.

Abstract: Delignification and bleaching of lignocellulosic material is obtained with catalyzed hydrogen peroxide in alkaline medium.

Abstract: Extraction of chlorine bleached kraft wood pulps with aqueous peracids at pH values of 7 or below, aqueous sulfites at pH values below 10 or with certain non-aqueous solvents provides extracted pulps having lower residual color and permits use of lesser quantities of alkali or chlorine dioxide in subsequent bleach steps to attain brightness and strength levels comparable to those attained with pulps treated by alkaline extraction at pH values of 10 or higher. At a comparable level of alkali and chlorine dioxide or hypochlorite application, extraction of chlorinated pulp with peracids provides bleached pulps with enhanced brightness.

Abstract: A method for delignifying and/or bleaching cellulose pulp adds to the cellulose pulp a liquid which contains chlorine dioxide, causes the pulp to react with the chlorine dioxide over a selected period of time, and then reduces the amount of available active chlorine, optionally to a negligible amount, either by reducing the amount of liquid accompanying the cellulose pulp and/or by displacing such liquid with a newly supplied liquid containing no active chlorine or at most only a small amount of active chlorine; the displaced liquor can be replenished with chlorine and optionally with chlorine dioxide, and then added mainly to fresh cellulose pulp in the same bleaching stage, and/or to cellulose pulp in another bleaching stage.

Abstract: The invention is a fibrous, cationic cellulose pulp product and the method for preparing it. A water suspension of cellulosic fiber is treated under alkaline conditions with a condensate of epichlorohydrin and dimethylamine. Up to 30 molar percent of the DMA may be replaced by a crosslinking agent such as ammonia or a lower aliphatic diamine. The process may be carried out at room or elevated temperatures. It is practical to add the condensate at one of the later alkaline stages of a bleaching process; e.g., an alkaline extraction or peroxide stage. This is most preferably done later than any chlorination or hypochlorite stages. The product shows greatly improved retention of acid and other anionic dyes. It also shows superior retention of some pigments and latices without the need for other cationic aids. In some cases a small amount of alum appears to have a synergistic retention effect with the cationic pulp product when used with titanium dioxide and certain anionic latices.

Abstract: A process for maintaining pulp viscosity while enhancing brightness during the bleaching stage or stages of pulp preparation in the manufacture of paper comprising adding an effective amount of melamine to paper pulp prior to or during the bleaching stage. One example adds melamine to one bleach stage of a chlorine bleaching sequence. One example adds melamine to one bleach stage of a chlorine bleaching sequence.

Abstract: A process for maintaining pulp viscosity during the bleaching stage or stages of pulp preparation in the manufacture of paper comprising adding an effective amount of caffeine or guanine prior to or during the bleaching stage. One example adds caffeine or guanine to one bleach stage of a chlorine bleaching sequence.

Abstract: The advantages of the serial application of chlorine dioxide and chlorine without intermediate wash during the bleaching of wood pulp in the absence of significant amounts of dissolved organic materials are improved by the presence of small quantities of dissolved chlorine in the chlorine dioxide solution.

Abstract: The adverse effects of dissolved organic material in the aqueous phase of pulp suspensions during bleaching using mixtures of chlorine dioxide and chlorine are overcome by applying the chlorine dioxide and chlorine serially to the pulp in two steps without an intermediate wash. An aqueous solution of chlorine dioxide and chlorine in which the chlorine constitutes from about 6 to about 10% of the total available chlorine of the solution is used in the first step and chlorine is used in the second step. The aqueous solutions are formed by dissolving in water chlorine dioxide and chlorine formed in a chlorine dioxide generator.

Abstract: The advantages of the serial application of chlorine dioxide and chlorine without intermediate wash during the bleaching of wood pulp in the absence of significant amounts of dissolved organic materials are improved by the presence of small quantities of dissolved chlorine in the chlorine dioxide solution.

Abstract: The adverse effects of dissolved organic material in the aqueous phase of pulp suspensions during bleaching using mixtures of chlorine dioxide and chlorine are overcome by applying the chlorine dioxide and chlorine serially to the pulp in two steps without an intermediate wash. An aqueous solution of chlorine dioxide and chlorine in which the chlorine constitutes from about 6 to about 10% of the total available chlorine of the solution is used in the first step and chlorine is used in the second step. The aqueous solutions are formed by dissolving in water chlorine dioxide and chlorine formed in a chlorine dioxide generator.

Abstract: The advantages of the serial application of chlorine dioxide and chlorine without intermediate wash during the bleaching of wood pulp in the absence of significant amounts of dissolved organic materials are improved by the presence of small quantities of dissolved chlorine in the chlorine dioxide solution.

Abstract: The invention relates to a process for bleaching preoxidized paper pulp enabling a pulp having a very high degree of whiteness to be obtained with a limited number of treatment steps and enabling pollution to be reduced without degrading the qualities of the pulp; such a process essentially comprises the combination of the three successive treatment steps, namely:(a) a first step of hot chlorination with gaseous chlorine at a temperature of between about 30.degree. and 80.degree. C., and preferably between 35.degree. and 50.degree. C., in the presence of urea used at a rate of 0.5 to 5% by weight of the chlorine used, and preferably from 1 to 3%, with a concentration of pulp of between 3 and 30%, and a duration of retention of the chlorine of 30 seconds to 45 minutes;(b) a second step of alkaline extraction in the presence of an oxidizing agent of the hypochlorite or peroxide type, at a temperature of between about 30.degree. and 70.degree. C., and at a pH of between about 8 and 12, and preferably between 10.

Abstract: Paper pulp is produced by a process in which raw sugar mill bagasse is moist depithed, wet bulk stored in the presence of an inorganic and organic preservative, wet depithed by hydraulic shearing in the presence of an inorganic color remover, pulped, washed, cleaned and dewatered.

Abstract: A pulp containing lignocellulosic fibers is treated with chlorine in two steps. In the first step, chlorine in the amount of 0.6-0.9 grams per gram of lignin in the fibers, is mixed in the gaseous state into the pulp and in a second step the reaction products, which contain chlorinated lignin, are removed by displacing the liquid in the pulp with a chlorine solution, the amount of active chlorine in the solution in the second step being between 0.1 and 0.3 grams per gram of the lignin initially present in the pulp. In this manner 92% delignification is achieved without any intermediate washing between the two steps and with a total amount of chlorine between 0.7 and 1.2 grams per gram of lignin. The consistency of the pulp in both steps is the same and is between 6 and 12%.

Abstract: Method and apparatus for the continuous distribution and mixing of high concentration pulp with at least one treatment fluid such as chlorine or chlorine dioxide. An enclosed housing has a cylindrical portion, a closed conical wall portion extending inwardly from one end of the cylindrical portion, and a generally converging open conical portion extending outwardly from the other end of the cylindrical portion. High concentration pulp is introduced into the cylindrical portion of the housing, and a rapid circular movement is imparted thereto by rapidly rotating rotor transport blades, so that the pulp is essentially fluidized. Treatment fluid is added to the pulp through the cylindrical housing portion to generally form a layer over pulp rotating in the cylindrical housing portion.

Abstract: The colored body content of the effluent from the alkali of a multi-stage cellulosic pulp bleach process is greatly reduced by extracting bleached cellulosic pulp with hypochlorite at a pH from about 6 to less than 9.

Abstract: A composition which consists essentially of a mixture of oligomeric and polymeric oxidation products of cellulose, hemicellulose and lignin containing carboxy, ether and hydroxy groups as obtained by the direct oxidation of a woody plant material, preferably in an aqueous suspension thereof, using alkali hypohalite in a one stage oxidation procedure or nitrogen dioxide, alkali periodate or lead tetraacetate followed by alkali chlorite or alkali hypochlorite in a two stage oxidation procedure. The resulting oxidation products as obtained by one of these specific processes are especially valuable as additives to a surface active detergent or cleaning agent.

Abstract: The delignification and bleaching of lignocellulosic products is effected by mixing an aqueous suspension of the lignocellulosic product with a chlorine-containing substance and an oxygen-containing substance, simultaneously or sequentially, and they, by reaction in situ, give rise to gases in the nascent state. The chlorine and/or oxygen are in the so-called "singlet" state, or in a state of higher energy. The treatment occurs at a temperature below 100.degree. C and for a time less than 60 minutes.

Abstract: A method for bleaching pulp comprising the steps of dewatering or thickening the pulp to a solids concentration of about 30-40 percent, and then treating the pulp with a first treatment liquid, in a vessel, having between 3 and 10 grams of chlorine gas dissolved therein, corresponding to a charge of 20-80 kg of chlorine per ton of pulp resulting in a solids concentration of the treated pulp of 6-15 percent. Treatment with a second liquid in the vessel and other treatment steps may also be performed.

Abstract: A process for bleaching pulp in tank comprises several steps. A pulp slurry and an oxidizing agent are supplied to a first tank compartment. The mixture of pulp slurry and oxidizing agent is agitated at a first power level that corresponds to an approximate minimum power level for a maximum reaction rate on a plot of reaction rate versus power level for a first residence time. The mixture is re-agitated in another tank compartment at a second power level that corresponds to an approximate minimum power level for a maximum reaction rate on a plot of reaction rate versus power level for a second residence time. The second power level is lower than said first power level and corresponds to the amount of unreacted oxidizing agent and unreacted pulp slurry.

Abstract: There is provided a process for the bleaching of woodpulp comprising reacting the pulp with chlorine dioxide until the chlorine dioxide is .[.at least partially.]. .Iadd.more than 50% .Iaddend.depleted and, thereafter, .Iadd.without an intermediate wash, .Iaddend.reacting the woodpulp with chlorine. .[.The process provides bleached pulps with excellent strength brightness, and color reversion properties..].