Abstract: A process for treatment of fibers is disclosed. The treatment comprises simultaneously and continuously macerating the fibers and exposing the fibers to superheated steam, ammonia gas and ethylenediamine gas. The treatment is carried out in a chamber where the fibers are subjected to the mechanical rubbing and crushing action of a plurality of rotating pins against channels disposed on the chamber interior wall. The treatment results in improved fiber water holding capacity and improved conversion efficiency in the production of biofuels from the treated fibers.

Abstract: Apparatus for washing and dewatering pulp including a pair of rotatable press rolls with a permeable outer surface in a casing including a vat in which the press rolls are installed is provided. A gap is provided between the vat and the press rolls as well as means for feeding the pulp into the gap between the rolls and the vat includes a first segment partially enclosing the first roll and a second segment partially enclosing the second roll, and casing members for each segment are pivotable about axes of rotation to open and close the casing, and the distance between the axes of rotation is less than the sum of the outer diameter of the two press rolls.

Abstract: A process for treatment of fibers is disclosed. The treatment comprises simultaneously and continuously macerating the fibers and exposing the fibers to superheated steam, ammonia gas and ethylenediamine gas. The treatment is carried out in a chamber where the fibers are subjected to the mechanical rubbing and crushing action of a plurality of rotating pins against channels disposed on the chamber interior wall. The treatment results in improved fiber water holding capacity and improved conversion efficiency in the production of ethanol from the treated fibers.

Abstract: A bearing cylinder for a screen assembly of a pressurized pulp diffuser, the bearing cylinder including: a plurality of segments of the bearing cylinder wherein the segments are arranged side-by-side to form the bearing cylinder; and each of said segments includes a first region formed of a hard material resistant to damage from sand and rocks, and a second region formed of a soft material that thermally expands and conforms to bearing surfaces opposite to the bearing cylinder.

Abstract: Digested softened non-defibrated chips are fed out from a bottom of a digester. The chips are fed out under an influence of a bottom scraper at the bottom of the digester and through an outlet tap at the bottom of the digester and onwards to an outlet line connected to the outlet tap. This takes place before the softened chips pass through a blow-valve arranged in the outlet line, across which blow-valve a pressure drop of at least 0.5 bar and at most 3-5 bar has been established. The chips are exposed to a displacement wash after the chips have passed the outlet tap. The displacement wash has been established in the flow of chips through the outlet line before the chips are defibrated by the pressure drop across the blow-valve.

Abstract: A method of manufacturing high purity fiber cement grades of cellulose fibers is described. Additional washing steps, coupled with an elevated temperature, are used in the process to extensively wash the pulps and remove substantially all COD components remaining in the pulps. The pulps are counter-currently washed by diffusion and dewatering at elevated temperatures following the brown stock washer systems. During the additional washing steps, the pulps are soaked in counter-current heated water for a pre-determined time and some chemicals may be introduced to chemically break down the COD components in the pulps and to make them more soluble in the aqueous solution. The additional washing steps can be performed using existing equipment at conventional pulp mills. A formulation and a process of making fiber reinforced cement composite materials are also described using the low COD and high purity cellulose fibers.

Abstract: A process for the bleaching of chemical pulp, comprising a first chlorine dioxide treatment (D) of the initial bleaching and chelation (Q) to be carried out in connection therewith, forming together a DQ treatment. The process is characterized in that the chelation is carried out at the pH of from 2 to 7, and it is followed by an alkalizing stage (N) of the pulp, without intermediate washing for raising the pH of the pulp to above 7 and at most to 12 prior to a following stage which is a washing step.

Abstract: A method for pulp processing includes a cold caustic extraction stage in which the spent cold caustic solution and the spent liquid used to wash the extracted pulp are concentrated by an evaporation system. The concentrated liquid can be used as part of the neutralization and cooking liquor in the pulp process, leading to increased efficiency without significant reduction in pulp quality. Highly concentrated filtrate from the cold caustic extraction stage may help reduce hemicellulose deposition on wood fiber during the cooking step.

Abstract: An apparatus for treating pulp including: at least one liquid-permeable surface rotating around a shaft, onto which surface a pulp layer is formed; a feeder to feed pulp to the apparatus for treatment on the liquid-permeable surface; an internal barrier defining a first pulp treatment section and a second pulp treatment section; the first treatment section receiving from the feeder a first type of pulp and the second treatment section receiving from the feeder a second type of pulp, wherein the first type of pulp is supplied to the feeder from a first pulp treatment stage in a pulping system and the second type of pulp is supplied to the feeder from a second pulp treatment stage in the pulping system, and a pulp discharge to discharge treated pulp from the apparatus, wherein the pulp discharge discharges the first type of pulp after treatment separately from discharging the second type of pulp after treatment, and a filtrate discharge to discharge filtrate flowing through the liquid-permeable from the apparat

Abstract: The present invention relates to a cosmetic cotton-like material having excellent air permeability that is prepared from the paper mulberry by removing fiber-binding substances such as pectin and lignin from the paper mulberry fiber, a preparation method thereof and a mask pack comprising the cotton-like material.

Abstract: The present invention relates to a process for the production of xylose and dissolving pulp from xylan-containing biomass, such as hardwood. The invention is based on prehydrolysis of the xylan-containing biomass with SO2 in specified conditions, followed by chromatographic fractionation, nanofiltration or precipitation crystallization of the xylose-containing prehydrolyzate to obtain a xylose product having a xylose content of at least 55% on DS. The dissolving pulp obtained from the process can be used for example for the production of viscose.

Abstract: A method of treating pulp on a porous surface of a rotating drum cylinder having a lower drum portion in a vat of pulp slurry and a radial array of filtrate conduits including: as the porous surface of the drum rotates through the vat, drawing filtrate from the slurry through the porous surface by the application of a suction to the filtrate conduits vacuum; draining the filtrate from the filtrate conduits into the filtrate chamber and to a filtrate suction conduit extending to an elevation below the vat; forming a pulp mat on the porous surface which passes filtrate and substantially blocks fibers in the pulp slurry; removing the pulp mat on the porous surface from the vat as the drum rotates; draining filtrate from the filtrate suction conduit, and before excessive gases passing through the porous surface enter the filtrate conduits, switching a fluid flow downstream of the filtrate conduits to a gas vent passage offset and below from a drum rotational axis.

Abstract: A method for the fractionation of lignocellulosic materials into cellulose, hemicelluloses and lignin in a batch or continuous process in a treatment with vaporous mixture of aliphatic alcohol, sulfur dioxide and water. Cooking conditions are varied to get different proportions of cellulose, hemicelluloses and lignin. Chemical recovery through pressure release is described.

Abstract: Methods for bleaching oxygen delignified and washed pumps having a consistency of between 8 and 20% are disclosed including a first chlorine dioxide bleaching step, washing the bleached pulp, subjecting the washed pulp to an alkaline extraction step to obtain an alkali-containing pulp, adding chlorine dioxide and adjusting the pH in a second chlorine dioxide bleaching step performed directly after the alkaline extraction step without an intermediate washing step, and subjecting the bleached alkali-containing pulp to a peroxide treatment step directly after the second chlorine dioxide bleaching step or with an intermediate washing step prior to the peroxide treatment step.

Abstract: The method and a device is for the dilution of dewatered cellulose pulp that maintains a consistency of 20-30% or greater. By shredding of the pulp to a finely divided dry-granulate, dilution to a homogeneous consistency in the medium consistency range can take place exclusively through hydrodynamic effects from the addition of dilution fluid. The dilution fluid is added to granulate at a position at which granulate is in free fall in a standpipe and above a level LiqLEV of diluted pulp in the standpipe. A number of nozzles are arranged around the periphery of the stand pipe, directed in towards the centre of the stand pipe, obliquely downwards in the direction of fall of the granulate. It is possible through this simplified procedure to avoid completely the conventional dilution screws, and this reduces the investment costs and operating costs, while at the same time unnecessary mechanical influence of the pulp fibres can be avoided.

Abstract: This invention relates to the delignification of lignocellulosic pulp. More particularly, the invention relates to sulfonation and bleaching of the alkali pulping produced by Kraft pulp processes or produced through combination of alkali pulping processes and extended delignification stages.

Abstract: Washing apparatus as well as methods for washing and dewatering a cellulose pulp are disclosed comprising a rotary drum with outer compartments for pulp washing, and a stationary casing surrounding the drum to define an annular space between the casing and the drum which is divided into zones by longitudinal seals. The function of the seals is optimized by a force measurement device for measuring forces acting on the longitudinal seal for measuring a biasing force of a spring package in the measurement device and for measurement of a force acting on a load transmission shaft of the device as well as an extractor for extracting a force acting against the seal in a direction away from the drum.

Abstract: In a rotary drum for condensing pulp from a pulp slurry vat, the drum including radial conduits delivering filtrate from a pulp mat on an outer surface of the drum to at least one filtrate conduit coaxial with a drum rotational axis, a valve segment in the filtrate conduit including: an outer surface juxtaposed against drainage outlets of the radial conduits as the conduits pass through an angular range extending from an upper drum position to an immersed in a vat position, wherein the valve segment does not block the drainage outlets during a majority of the rotation of the drum; at least one inlet aperture on the outer surface aligned with the drainage outlets, said inlet aperture extending at least a majority of a width of the valve segment, and a closed passage extending from the inlet aperture to a gas vent external to the filtrate conduit, wherein the closed passage is offset from and below a centerline of the filtrate conduit.

Abstract: The present invention relates to a washing apparatus (2) for washing of cellulose pulp, comprising a rotatable drum (4), a stationary support (6), a discharge device (8) that has an outlet orifice (9), a casing that surround the drum and that forms a longitudinal discharge opening (10) and a conveyer worm (12) arranged below the outlet orifice for reception and removal of washed pulp. The conveyer worm (12) is movably arranged relatively the support (6) between a first position (P1), in which the conveyer worm receives washed pulp during operation, and a second position (P2), in which the outlet orifice (9) is exposed and access to the drum (4) via the outlet orifice is possible for carrying out service, maintenance and inspection of the washing apparatus (2).

Abstract: A pulp production process can produce pulp at high yield without using sodium sulfide and high-temperature/high-pressure conditions if compared with the Kraft process and also collect lignin. Pulp is produced by processing wood chips for hydrophlicization at room temperature, using a dilute caustic soda aqueous solution, selectively partially modifying lignin in dilute nitric acid and digesting the wood chips by means of a dilute caustic soda aqueous solution under the atmospheric pressure. Lignin is agglomerated and sorted out from the isolated black liquor.

Abstract: A bearing cylinder for a screen assembly of a pressurized pulp diffuser, the bearing cylinder including: a plurality of segments of the bearing cylinder wherein the segments are arranged side-by-side to form the bearing cylinder; and each of said segments includes a first region formed of a hard material resistant to damage from sand and rocks, and a second region formed of a soft material that thermally expands and conforms to bearing surfaces opposite to the bearing cylinder.

Abstract: Lignocellulosic biomass comprising lignin is treated by selective extraction and oxidation of lignin using a solvent solution comprising water in combination with at least one Mn(III) salt to produce readily saccharifiable carbohydrate enriched biomass.

Abstract: Apparatus for creating a seal between an axle journal and a bearing housing is disclosed, particularly for use in apparatus for dewatering or washing material suspensions. The apparatus includes a stator ring, a pair of diagonally disposed guide pins supporting the stator ring with respect to the bearing housing so that the stator ring can be angled in a plane with respect to the pair of guide pins, a sealing ring for creating a seal between the stator ring and the axle journal, a bellows for creating a seal between the bearing housing and the stator ring, and at least one resilient member for urging the stator ring in abutment against the sealing ring.

Abstract: A method for producing fibrous material from softwood, hardwood, or annual plants, including preparing a solution of chemicals having one of: more than 5% of chemicals for softwood, more than 3.5% of chemicals for hardwood, or more than 2.5% of chemicals for annual plants. The method includes: mixing the solution of chemicals with the lignocellulosic material in a predetermined liquor ratio; heating the solution of chemicals and the lignocellulosic material to a temperature above room temperature; and, after the heating, performing one of: removing a free-flowing portion of the solution of chemicals and digesting the lignocellulosic material in a vapor phase, or digesting the lignocellulosic material in a liquid phase and separating the free-flowing portion of the solution of chemicals and the lignocellulosic material. The produced fibrous material has a lignin content of at least 15% for softwood, at least 12% for hardwood, and at least 10% for annual plants.

Abstract: A process for the bleaching of chemical pulp, comprising a first chlorine dioxide treatment (D) of the initial bleaching and chelation (Q) to be carried out in connection therewith, forming together a DQ treatment. The process is characterized in that the chelation is carried out at the pH of from 2 to 7, and it is followed by an alkalizing stage (N) of the pulp, without intermediate washing for raising the pH of the pulp to above 7 and at most to 12 prior to a following stage which is a washing step.

Abstract: A process for the bleaching of chemical pulp, wherein the initial bleaching of the pulp includes a first chlorine dioxide treatment (D0) and a following alkaline treatment with oxygen and hydrogen peroxide (EOP), which stages are separated from each other with a washing stage, and a treatment of the pulp to reduce the content of transition metals of the pulp prior to the peroxide treatment. The process is characterized in that alkali is added to the pulp after addition of chlorine dioxide in the D0 stage to adjust the pH of the pulp to neutral or basic (N stage) prior to the washing stage following the chlorine dioxide stage, whereby the initial bleaching includes the sequence D0N EOP.

Abstract: An improved method for treating lignocellulosic material, including a prehydrolysis-mass transfer process, which produces a concentrated hydrolysate volume during the time required for the hydrolysis itself. The improved process comprises the heating of the digester and chip content by direct steam to the required hydrolysis temperature, starting a flow of hot, stored hydrolysate to the top of the chip bed in order to create a trickle-bed type down-flow of hydrolysate, collecting a first fraction of the trickled-down hydrolysate as a product fraction, adding extraction liquid and continuing the trickle flow to collect a second hydrolysate fraction, which will be discharged from the digester to a hot hydrolysate storage tank to be used as the first trickle flow liquid in the next batch.

Abstract: A vacuum drum washer is designed to enable the use of an end-draining drum for drum lengths exceeding 20 feet. The drum washer includes a cylindrical drum having a mesh screen defining an exterior wall. A plurality of outer filtrate channels are disposed radially inward from the mesh screen. A plurality of inner filtrate channels are disposed radially inward from the outer filtrate channels and extend along generally less than an entire length of the drum. A transfer channel connects the outer filtrate channels and the inner filtrate channels. A plurality of radial drainage chutes are disposed adjacent a head end of the outer and inner filtrate channels, which direct the filtrate to a drain valve.

Abstract: Provided are a method for producing bleached pulp, comprising processing unbleached pulp obtained by cooking a lignocellulose substance, for alkali-oxygen bleaching followed by treatment with peroxomonosulfuric acid and thereafter by multistage chlorine-free bleaching treatment starting from chlorine dioxide treatment; a method for producing bleached pulp, comprising processing the unbleached pulp for alkali-oxygen bleaching followed by chlorine-free bleaching treatment or totally chlorine-free bleaching treatment to bleach it to a degree of brightness of from 70 to 89%, and further followed by treatment with peroxomonosulfuric acid; and paper produced by the use of the bleached pulp produced according to these production methods, at a papermaking pH of at most 6.

Abstract: A method of producing a modified pulp comprising treating wood chips in an extraction process to remove hemicellose to form treated wood chips; and subjecting said treated wood chips to chemical or semichemical pulping to form a modified Kraft pulp wherein the amount of hemicellulose contained in the modified Kraft pulp is from about 5 to about 10% by dry weight of the modified pulp.

Abstract: Disclosed is a closed floatation conventional de-inking process adopted in the recycled paper processing plants, in which, ink separation and removal constitutes a major task. The specific concerns of this invention are the concept and the equipment for the separation and removal of the ink and ash from the pulp slurry contaminated with ink, clay and stickies.

Abstract: The arrangement concerns an improved design for at least one of the cooling, dilution and washing at the bottom of a continuous digester for the production of cellulose pulp. By arranging at least one extra strainer section above the lowermost strainer section, with the addition of washing fluid or dilution fluid between the extra strainer section and the lowermost strainer section, more washing fluid can be added at the bottom of the digester without counteracting the flow of the column of chips. This provides space for the increase of production, for improvement of the flow of the column of chips, or for combinations of these effects while retaining good cooling, washing and dilution at the bottom of the digester.

Abstract: Process for bleaching of pulps following cooking of the lignocellulosic material with soda and anthraquinone. The process may produce a whiteness on par with the bleaching of kraft pulp when using a similar bleaching sequence. In some instances, the bleaching sequence may be O-A-Do-Eop-D, O-A-ZDo-Eop-D, A-Do, or A-ZDO.

Abstract: Disclosed is a process for producing pulp utilizing bamboo, comprising finely cutting the bamboo into short segments and subjecting the cut bamboo to screening and washing processes to thereby produce dissolving pulp capable of achieving reduced consumption of chemical agents used during pre-hydrolysis and pulping processes and case of reaction, and having superior quality and high yield. Further, provided are also a process for producing fiber (dissolving) pulp utilizing bamboo, capable of preventing generation of dioxin by bleaching the pulp via ECF or TCF bleaching, and a pulp produced using the same.

Abstract: A rotary drum filter has a plurality of longitudinally extending division grids mounted about the outer circumference of a drum. A plurality of corrugated sheets are provided, with the leading and trailing edges of each sheet mounted to circumferentially adjacent pairs of division grids to define filtrate compartments. An equivalent number of perforated filter plates are also provided. Each filter plate is attached to the top of a corrugated sheet and has a leading edge and a trailing edge that are set back from the leading edge and trailing edge of the corrugated sheet. A seal clip is positioned near the leading edge of each corrugated sheet. A seal member or seal members is/are held in place by the seal clip and is/are positioned at the face of the leading edge of each corrugated sheet or beneath and near the face or each corrugated sheet.

Abstract: The present invention serves for loading a pulp suspension (S) with calcium carbonate. Liquid calcium hydroxide as milk of lime (7) is added during or before the pulp operation (1) carried out to form the pulp. By introducing gaseous carbon dioxide (8) into the pulp suspension thus treated, a chemical reaction is triggered therein, in which the finely divided calcium carbonate is precipitated. The present invention is particularly economic and effective due to the early addition of calcium oxide or calcium hydroxide.

Abstract: An apparatus for treating pulp including: at least one liquid-permeable surface rotating around a shaft, onto which surface a pulp layer is formed; a feeder to feed pulp to the apparatus for treatment on the liquid-permeable surface; an internal barrier defining a first pulp treatment section and a second pulp treatment section; the first treatment section receiving from the feeder a first type of pulp and the second treatment section receiving from the feeder a second type of pulp, wherein the first type of pulp is supplied to the feeder from a first pulp treatment stage in a pulping system and the second type of pulp is supplied to the feeder from a second pulp treatment stage in the pulping system, and a pulp discharge to discharge treated pulp from the apparatus, wherein the pulp discharge discharges the first type of pulp after treatment separately from discharging the second type of pulp after treatment, and a filtrate discharge to discharge filtrate flowing through the liquid-permeable from the apparat

Abstract: A method for producing paper pulp from a lignocellulosie vegetable raw material. The method includes contacting the raw material with a mixture of formic acid and acetic acid (in an amount more than 5 wt. % of the mixture) at a temperature and for a suitable reaction time, the whole being performed at room temperature. The paper pulp is separated from the organic phase and optionally bleached with ozone. The organic phase is treated to enable the recycling of the formic and acetic acids and the extraction of lignins, sugars and excess acetic acid.

Abstract: A process of treating a lignocellulosic material includes a pre-extraction step in which hemicellulose is extracted from the lignocellulosic material. In one embodiment, the pre-extraction step involves contacting the lignocellulosic material with an aqueous solution under conditions that release acidic material from the lignocellulosic material into the aqueous solution, and the aqueous solution includes a basic material that at least partly neutralizes the acidic material so that the aqueous solution at the end of the pre-extraction step has a pH within a range of from 4.5 to 11. The process also includes a pulping step, after the pre-extraction step, in which the lignocellulosic material is separated into pulp. The process further includes an adsorption step, after the pulping step, in which hemicellulose is adsorbed on the pulp.

Abstract: Wood chips having low bleachability are impregnated with a chemical liquor at a pH range of 7-12 in aqueous solution and the chemical liquor from the impregnated chips is drained, whereby extractives contained in the chips and consuming bleaching agents can be removed to improve the effect of bleaching agents in a subsequent bleaching step. Bleached mechanical pulp is prepared by defibration by primary refining—bleaching—beating by secondary refining wherein pulp fibers are washed after defibrating wood chips having low bleachability and before bleaching the pulp fibers, whereby the amount of bleaching agents used can be reduced and bleached mechanical pulp having a Hunter brightness of 45-65% after secondary refining can be obtained.

Abstract: The method is for bleaching cellulose pulp in a bleach line that has at least two bleaching steps. The filtrate distribution is led up through the bleaching line counter-currently to the flow of cellulose pulp established in the bleaching line. A single joint main conduit is used for the bleaching steps. Wash filtrates obtained from the wash steps, used after or before the bleaching step, are led in conduits to branch locations on the main conduit that are positioned downstream of the branch location for drawing off of wash and/or dilution liquor for the wash step in question. All branch points in the joint main conduit are in fluid communication with one another along the main conduit.

Abstract: The disclosure provides a process of modifying a seed based fiber (SBF) to form an enhanced fiber additive (EFA). The process includes an acid treatment step and optionally at least one fiber modification step. Preferred EFA products and uses are described.

Abstract: The digester and method are for the continuous cooking of pulp. At least two withdrawal positions (11E, 11D) for cooking fluid are arranged at different heights in the digester (10). The cooking fluid in the first and second position is withdrawn after the chips have had a retention time that differs by at least 10 minutes. The differential pressure between the positions is determined and when this exceeds a pre-determined level, a connection (17E) opens between these positions, establishing a flow parallel to a flow of cooking fluid between these positions in the digester. Several withdrawal positions are preferably connected in a common shunt system (17A-17F), with valves (18A-18F), controlled by the differential pressure, that are located between adjacent positions.

Abstract: A vacuum drum washer is designed to enable the use of an end-draining drum for drum lengths exceeding 20 feet. The drum washer includes a cylindrical drum having a mesh screen defining an exterior wall. A plurality of outer filtrate channels are disposed radially inward from the mesh screen. A plurality of inner filtrate channels are disposed radially inward from the outer filtrate channels and extend along generally less than an entire length of the drum. A transfer channel connects the outer filtrate channels and the inner filtrate channels. A plurality of radial drainage chutes are disposed adjacent a head end of the outer and inner filtrate channels, which direct the filtrate to a drain valve.

Abstract: Countercurrent extraction of lignocellulosic biomass such as trees, grasses, shrubs, and agricultural residues or waste involves the separation of cellulose fibers from other constituents, for subsequent use in the manufacture of paper, plastics, ethanol, and other industrial chemicals. Systems and methods involve continuous, multiple processing steps that may include chemical reactions with mixing at elevated temperature and/or pressure, efficient reagent or solvent utilization, filtration at elevated temperature and/or pressure, controlled discharge of liquid and solid products, and energy recuperation.

Abstract: A process for high temperature peroxide bleaching of pulp in which pulp is retained at high temperature and pressure to increase bleaching activity but in which the pulp is cooled prior to discharge from the pressure vessel below the flash point thereby resulting in lower energy, nonviolent discharge. Through the use of a heat exchanger, the cooling of the pulp can be performed using recycled filtrate containing residual peroxide, which encourages further bleaching during atmospheric retention. The heat exchanger is also used to heat a water stream, which can be used earlier in the pulping process, resulting in cost savings because energy within the system is retained to a greater degree.

Abstract: Separation of dissolved and colloidal high molecular weight organic by-products from liquors or filtrates in a cellulosic pulping process to improve the overall efficiency of the process.

Abstract: The method is for distributing cellulose pulp that has a 2-12% consistency. A manifoid housing is in fluid communication with distributor housing. The distributor housing has holes that are distributed along a generatrix of the distribution housing. The cellulose pulp is fed into an inlet of the manifold housing. The feed screw is rotated to convey the cellulose pulp in the transverse direction through the distributor housing. The feed screw sweeps across the holes in the distributor housing to urge the cellulose pulp through the holes. The cellulose pulp is uniformly fed through the holes and then through an inlet to dewatering drums. The cellulose pulp is run between the dewatering drums and a trough to form a pulp web. The pulp web is dewatered in a press nip formed between the dewatering drums. The dewatered pulp web is collected by a feed screw.

Abstract: A pulp product that has a low COD is comprised of an unbleached pulp that is soaked and washed in alkaline water for a sufficient time so that the COD after soaking and washing is less than or equal to 3.0 kg/1000 kg of dry pulp. The pulp is produced by repetitively soaking and washing an unbleached pulp in alkaline water that is never allowed to drop below pH 7.0. The pulp is soaked and washed for a total of at least 400 minutes at an elevated temperature to produce the pulp product that has a low COD.

Abstract: The invention relates to a method for the modification of cellulose fiber with the object of increasing the strength properties of the pulp. Cellulose derivative, preferably in the form of CMC, is added in association with alkali cooking and/or delignification of cellulose chips in a suspension with treatment fluid, in an amount exceeding 2 kg, preferably at least 5–7 kg, per ton of cellulose fibers. The addition of cellulose derivative to the suspension takes place when the suspension has a concentration of calcium released from the cellulose exceeding 20 mg/l. The conditions required for an efficient deposit of cellulose derivative onto the cellulose fibers can be established in this way, where the natural content of calcium in the wood raw material has been released and contributes to a high ionic strength, while an advantageous high temperature is established. No additional process stages are required and operating costs can be kept low.