Abstract: A process for the continuous digestion of cellulosic fiber material is described wherein the material is impregnated with liquid in a closed system comprising a concurrent flow zone and a countercurrent flow zone, the liquid in the concurrent flow zone including black liquor and possibly white liquor and the liquid in the countercurrent flow zone including white liquor. Liquid is withdrawn from the impregnation system at a point located between the concurrent flow zone and the countercurrent flow zone. Besides white liquor a predetermined amount of black liquor is added to the countercurrent flow zone in order to obtain a high liquid to wood ratio in the inlet of the digester.

Abstract: Processes for prepariing kraft pulp are disclosed. The processes include pretreating cellulosic material or chips with spent cooking liquor at the temperature of about 20.degree. to 100.degree. C., followed by heating the impregnated chips at the temperature of from about 120.degree. to 180.degree. C., followed by digestion of the lignin with white liquor, which is facilitated by using this pretreatment process.

Abstract: A continuous, upright, digester for paper pulp is utilized as a structural support for accessory vessels, such as a chip bin and flash tanks. Generally horizontal steel beams are connected to the digester and extend outwardly from opposite sides of the digester vessel. One set of beams is connected to the impregnation vessel, and supports the chip bin on them. A steaming vessel may be mounted on a horizontal platform below the chip bin. On the opposite side of the digester, the second horizontal beams extend to a pair of vertical legs spaced apart approximately the diameter of the digester. First and second flash tanks, one above the other, are supported by the second set of horizontal beams, and a third set below the second set, those beams--and structures connected to them--being the only support for the flash tanks.

Abstract: In a method of producing high-yield pulp from pulp chip material containing lignocellulose the material is treated with steam in a steam treating station (1) for driving air out of the material and heating the latter. Heat treated material is mixed in a mixing station (8) with a liquid containing chemicals. The mixture of steam treated material and said liquid is transferred from the mixing station to an impregnation station (25) for impregnating the material by means of said chemicals. Impregnated material is supplied to a refining station (36) for refining the material. According to the invention the steam treated material is mixed with said liquid in proportions, such that the created mixture of material and liquid leaving the mixing station (8) assumes a flowing pumpable consistency. Further, said flowing mixture is pumped from the mixing station (8) to the impregnation station (25).

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

Abstract: The invention relates to a process for continuous cooking of cellulose. In the process, wood chips (11) are impregnated (1) with cooking lye (10), after which the wood chips impregnated with cooking lye is mixed (27) with spent liquor (18) in order to transfer (12) it into the upper portion of a pressurized digester (2). The transfer liquor used for the transfer of the wood chips in the preceding step is separated (26) from the impregnated wood chips in the upper portion of the digester (2) and is recycled (13,14) to the preceding step. After this, the chips are conducted from the digester (2) downwards into the cooking zone (24) and from there on to the washing zone (24), whereby a mixture of spent lye and wash lye, i.e. spent liquor (18) is removed from between the cooking and washing zones (19) and a portion (21) of the liquor removed from the digester (2) is expansion evaporized (5,6) in order to recover heat in the form of steam (22,23).

Abstract: A method for the production of delignified wood pulp is provided which result in said pulp's having improved delignification ratios. In accordance with preferred embodiments, brownstocks are substantially uniformly treated with aqueous alkaline solution while in a state of low consistency. The consistency is then increased to values preferably in excess of about 20% and the brownstock treated with oxygen to effect delignification. The processes of the invention provide surprising improvements over prior methods in the high strength, low lignin containing pulps may be formed thereby. These pulps can be further bleached to high brightness with less subsequent bleach chemical.

Abstract: A process for the continuous digestion of cellulosic fiber material is described wherein the material is impregnated with liquid in a closed system comprising a concurrent flow zone and a countercurrent flow zone, the liquid in the concurrent flow zone including black liquor and possibly white liquor and the liquid in the countercurrent flow zone including white liquor. Liquid is withdrawn from the impregnation system at a point located between the concurrent flow zone and the countercurrent flow zone. Besides white liquor a predetermined amount of black liquor is added to the countercurrent flow zone in order to obtain a high liquid to wood ratio in the inlet of the digester.

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: A method and apparatus provide for the continuous digestion of comminuted cellulosic fibrous material (e.g. wood chips) to produce paper pulp, with increased sulfidity. When black liquor is withdrawn from the continuous digester, instead of merely passing it to a pair of flash tanks and then to recovery, the concentrated liquor from a first flash tank is fed to a vessel in which the comminuted material is slurried with a liquid. Since the black liquor remains in intimate contact with the chips for a significant period of time, the lignin in the chips is partly sulfonized. Ultimately the black liquor is replaced with white liquor or the like, and the separated out black liquor is circulated to recovery or disposal. A high pressure feeder and a solids/liquid separator are utilized.

Abstract: The invention concerns a method for the treatment of the spent liquors obtained from pulp production processes in the wood-processing industry, in which method the waste obtained from a chemical cooking process and that obtained from a mechanical process are merged for joint treatment. The chemical process may be e.g. a sulphate process and the mechanical process e.g. a chemi-thermomechanical process (CTMP), and the invention presupposes that the facilities for these processes are located close by each other, suitably within the same industrial complex. The essential feature of the invention is that the spent liquor of the CTMP is used as wash water in counter-current washing of the pulp obtained from the chemical process.

Abstract: In the method for the manufacture of a paper pulp for currency use from a stock comprising textile fibers, the operations of boiling, bleaching, chopping, breaking, cutting and washing of the textile fibers are performed in at least one treatment machine (10, 40) of the type having two co-rotating screws, in a plurality of phases taking place successively and continuously. The operations include a phase of feeding and mixing the stock with water, at least oen compression phase, at least one phase of shearing of the textile fibers, at least one phase of treatment of introduction of boiling and bleaching reagents, at least one phase of washing of the bleached pulp by introduction of washing water, and a phase of transferring and evacuating the bleached and washed pulp.

Abstract: A method for the continuous countercurrent production of lignins and sugars from wood and other ligno cellulosic materials by organosolv delignification or saccharification at elevated temperatures and pressures is disclosed. The novel method comprises: (a) continuously introducing comminuted lignocellulose materials with a natural mositure content into a reaction vessel from one end; (b) continuously introducing a cooking liquor comprising a major proportion of organic solvent, a minor proportion of water, and a slight amount of inorganic acid countercurrently into the reaction vessel from the opposite end; (c) causing the comminuted lignocellulosic material to be contacted by the cooking liquor; and (d) continuously withdrawing cooking liquor from the reaction vessel after it has commingled with and has dissolved sugars and lignin and other substances from the comminuted lignocellulosic material.

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

Abstract: A method for producing low fines content pulp having successive treatment stages in each of which compressive and shearing forces are applied to the cellulosic fiber while simultaneously one or more chemicals are added. Gradual breakdown of the fibers is achieved with resulting low fines production whereby the pulp may be used for tissue, fluff and towel products.

Abstract: Bamboo can be formed into a suitable pulp if prior to digestion it undergoes a process of shredding, washing and wet depithing. The fibers are then chemically digested preferably by a process which uses rapid pressure drops to open the fibers using the energy contained in the wet superheated fibers.

Abstract: Method and apparatus for delignifying chemical pulp by means of oxygen, in which an aqueous slurry of chemical pulp is formed, then mixed with a caustic agent, followed by contact with a delignifying fluid. Water is drained off the slurry without reduction of pressure and while maintaining temperature following which the resulting slurry is maintained under these temperature and pressure conditions for a discrete period of time. The thus-obtained treated slurry is then washed.

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

Abstract: A process is disclosed for the pretreatment of lignocellulosic fibrous materials prior to delingification. The process in one of its embodiments is comprised of the following steps:1. Contacting the pulp material with treated filtrate and alkali for a short reaction period of about 1 to 2 minutes at 40.degree. C.,2. Withdrawing part of the liquid phase by filtration,3. Displacing substantially all of the remaining liquid phase with treated filtrate, and4. Allowing the pulp to react under conditions normally used for alkaline extraction or oxygen delignification.The treated filtrate is obtained by subjecting the liquor removed from the pulp at steps 2 and 3 to temperature of 5.degree. to 60.degree. C. for periods of about 5 to 10 minutes. Alternatively, step 3 can be eleminated.

Abstract: A process for the production of sugars, and optionally cellulose and lignin, from lignocellulosic vegetable materials which comprises subjecting the vegetable materials to a chemical pretreatment with a mixture of water and lower aliphatic alcohols and/or ketones at a temperature from 100.degree. to 190.degree. C. for a period of from 4 hours to 2 minutes with control of the breakdown of the hemicellulose components followed by separation of residue and a subsequent main chemical treatment with a similar solvent mixture at elevated temperatures for a further period of from 6 hours to 2 minutes.

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: A method for the treatment of a suspension, such as pulp, with one or more treatment liquids in a manner that maximizes treatment efficiency and minimizes heat loss. The pulp flows in a flow path confined to a given web thickness, and has first and second opposite sides. Treatment liquid is added to the first side of the flow path at spaced predetermined points along its length. Liquid displaced by the treatment liquid is withdrawn from the second side of the flow path at substantially the predetermined points. The displaced liquid at the first predetermined point along the flow path consists essentially of original suspension liquid, while the liquid fraction of the pulp past the last predetermined point of the flow path is composed mainly of treatment liquid added at the last predetermined point. Treatment can be accomplished at super-atmospheric pressure and at a temperature above 100.degree. C. The web thickness is between about 50-500 mm.

Abstract: A process for thermomechanical digestion using a multiple blowdown technique. The digestion chemical is added just prior to blowdown which results in a concentration of digesting chemicals on the fiber. The process can be carried out with a digester having multiple chambers, each at a lower pressure has many advantages in forming pulps suitable for newsprint or fine papers from wood and vegetable fiber sources. The digester should be of a kind where the fiber will have a greater residence time in subsequent chambers.

Abstract: The brightness of a thermomechanical pulp can be improved if a serial multiple blowdown technique is used and a bleachant is present at an effective concentration throughout the thermomechanical pulping process.

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: A method and apparatus are provided for effecting presteaming and deaeration of wood chips, or like comminuted cellulosic fibrous material. Presteaming takes place in a vertical presteaming vessel, utilizing a plurality of uniformly radially spaced nozzles adjacent the bottom of the vessel, a plurality of generally uniformly radially spaced steam introduction pipes in a central portion of the vessel, and a pair of synchronized rotating valves for feeding steam to the introduction nozzles and pipes in a coordinated manner. After presteaming, the chips pass through a chips meter to a vertical chute in which they are entrained in liquid, and then pass to a horizontal deaerating vessel. In the deaerating vessel, deaerated liquid is passed in a path generally perpendicular to the path of the material flowing through the deaeration vessel.

Abstract: A process for continuous digestion of wood chips which are passed through a heating zone, a digesting zone and a cooling zone in contact with cooking liquor is disclosed. In this process the wood chips are fed into and the liquid phase removed from the input end of the heating zone in such relative quantities that their heat-capacity flows are of approximately the same order of magnitude.

Abstract: A process is provided for pretreating particulate lignocellulosic material to remove heavy metals and resin without any delignification or defibration, which comprises washing particulate lignocellulosic material; compressing the washed material to a solids content of at least 40% to remove absorbed and excess liquid; impregnating the compressed material with an alkaline aqueous solution comprising alkali and at least one of a heavy metal ion complexing agent and a heavy metal ion reducing agent; heating the impregnated material at a temperature within the range from abut 50.degree. to 100.degree. C. for up to approximately 0.75 hour; compressing the pretreated material to a solids content of at least 40%; and separating undiluted liquor squeezed out during the compression, while maintaining conditions during the pretreating such that the pH of the squeezed-out liquor is within the range from about 4 to about 9.

Abstract: In the continuous manufacture of cellulose pulp it has been found that air often remains in the lignocellulosic material subsequent to steaming the same. These air inclusions cause the lignocellulosic material to float in the cooking liquid, which results in interruptions in the digestion process. This problem is solved by means of the present invention, which relates to a method in which prior to being steamed, the lignocellulosic material is brought into contact with a heating medium. The method is characterized by supplying the heating medium to the advancing lignocellulosic material at several occasions; by distributing the heating medium in a manner such as to increase the temperature of the material in the direction in which it is advanced; and by separating condensed liquid from the lignocellulosic material.The invention also relates to apparatus for carrying out the above method.

Abstract: Comminuted cellulosic fibrous material, such as wood chips, are treated in a continuous digester to produce paper pulp or the like in a manner providing completely uniform treatment of the chips. The chips are introduced in a feed liquid slurry into the top of the digester, with a swirling action, and establish a vertical column in the digester having a substantially horizontal top, with some liquid between the top of the digester and the top of the chips. Below the top of the chips the feed liquor is withdrawn through a first set of withdrawal screens, and recirculated to entrain other chips to feed them to the top of the vessel. At other vertically spaced areas of the digester other screens are provided for withdrawing, cooking, quench, washing, and like liquors, and effecting recirculation thereof. At each screen set a plurality of nozzles are provided circumferentially spaced around the digester, each nozzle cooperating with only a particular radial segment of the screens.

Abstract: An apparatus for continuously producing wood pulp from wood shavings comprising a screw which rotates within a hollow cylinder. The hollow interior of the cylinder is divided into a pressure zone and a grinding and bleaching zone, the shavings being subjected to at least partially defibrillation under a high, continuously-increasing pressure in the pressure zone and then being simultaneously further defibrillated and bleached in the grinding and bleaching zone. The grinding and bleaching zone includes a plurality of pin planes, each plane being formed of at least three radially extending pins which project through the wall of the cylinder, the planes being spaced apart along the length of the screw.

Abstract: An improved pulping process for producing high yield pulps from woody lignocellulosic material wherein the lignocellulosic material is treated with a pulping chemical and mechanically defibrated. The improvement comprises pre-treating the lignocellulosic material by impregnating same with a loweralkanolamine so as to cause softening of lignin in the material and to promote fiber separation. As a result, pulping chemical and refining energy consumption as well as vapor and liquid effluent pollution are significantly reduced.

Abstract: A process for the production of sugars, and optionally cellulose and lignin, from lignocellulosic vegetable materials which comprises subjecting the vegetable materials to a chemical pretreatment with a mixture of water and lower aliphatic alcohols and/or ketones at a temperature from 100.degree. to 190.degree. C. for a period of from 4 hours to 2 minutes with control of the breakdown of the hemicellulose components followed by separation of residue and a subsequent main chemical treatment with a similar solvent mixture at elevated temperatures for a further period of from 6 hours to 2 minutes.

Abstract: This invention relates generally to the extraction process and provides a novel process and reactor for the continuous extraction of vegetable-fibre material such as wood chips. The process comprises a two stage process, the first stage comprising an extraction process using a methanol:water mixture and the second stage using the same extraction liquid as the first with a greater proportion of water, with sodium hydroxide and anthraquinone. A part of the extraction liquid which is saturated by extraction substances is continually carried away at each stage and after extraction, the mixture is subjected to washing. This process has eliminated the heavy pollution produced by the prior art processes and also has reduced the cost and complexity of the prior art processes.

Abstract: A process and apparatus for producing pulp from impregnated cellulose-containing starting materials such as wood, straw, grass, waste materials etc. in a compacting apparatus comprising a shell (1) and two mutually opposite pistons (4, 4') contained in the shell. The material to be compacted is disposed between the pistons and constitutes a resistive electrical load. The pistons are movable relative to each other and the shell is movable relative to the pistons. The impregnated starting materials are digested at a relatively low hydromodulus of 0.5 to 2 with a direct action of heat on the impregnated starting materials in the compacting apparatus at a digesting temperature of 160.degree. to 300.degree. C. The digesting times are short and depend on the digesting temperature.

Abstract: A two-stage oxygen bleaching of chemical cellulose pulp is provided, in which an alkaline oxygen bleaching stage is preceded by a nitrogen dioxide activating stage in which oxygen is added to the activating stage in an amount such that nitrogen monoxide formed as an intermediate during the activation process is consumed, so regulating the amount of oxygen added that when the activation reaction is practically complete, substantially all of the nitrogen dioxide and nitrogen monoxide has been consumed.

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: Good temperature and pH control as well as uniform mixing of pulp or other fibrous materials is achieved in a medium consistency oxygen delignification method and system. Alkaline chemicals are sprayed, optionally using oxygen gas as the atomizing agent, into the gas space above the level of pulp maintained in one or more substantially horizontal tubular reaction vessels. At least a part of the steam requirement of the reaction is added only after the major portion of alkaline chemicals has been added to the system. In other embodiments of the invention, alkaline chemicals may be injected into the substantially vertical conduit connecting two reaction vessels or two different alkaline chemicals may be injected at different points in the system.

Abstract: A process is provided for heating up wood chips in one or more stages at progressively higher temperatures prior to steaming and pulping in an economical manner at a considerable cost saving; heating the chips in at least a first preheating stage directly with moisture-saturated hot air, optionally admixed with inert gas, having a temperature within the range from about 55.degree. to about 99.degree. C., preferably from 70.degree. to 90.degree. C., having been brought to that temperature in a heat exchanger with hot water or air heaters with waste gases, such as gases drawn at different levels from an evaporator, for example, a Lockman pre-evaporator column.

Abstract: A process for producing corrugating medium pulp, fuel, and other products from a wide variety of woody materials is disclosed. In one embodiment a pulping solution is produced by cooking green chips in a water solution of monoethanolamine and subsequently collecting the liquor produced. Pulp is then produced by digesting chips under a vapor dome of the pulping solution, or cooking the chips in the solution and subsequently digesting under a vapor dome. Digested chips are then refined in pulping solution to produce corrugated medium pulp. In another embodiment, fuel may be produced by digesting woody material under a vapor dome with sulfur dioxide and ammonia. The digested chips then yield a lignin containing liquor which has a good fuel value and may be used as a liquid fuel or impregnate for woody material. In another embodiment the pulping solution is used as a hard wood conversion resin. Wood is impregnated and pressed. The pressed wood may have a density of twice the original wood.

Abstract: An apparatus and process for the oxygen delignification of pulp is provided in which the pulp is transported by means of timing screws in essentially plug flow through one or more substantially horizontal reactor tubes. Oxygen gas is injected into the system at a point adjacent to the pulp inlet and travels concurrently in substantially plug flow with the pulp through the system. In this manner, the pulp is initially exposed to gas of a high oxygen partial pressure while gas vented from the system adjacent the pulp outlet is of low oxygen partial pressure and has a high content of diluent gases. The process and apparatus avoid the formation of gas pockets and hot spots which may adversely affect the pulp. In an alternate embodiment, a countercurrent gas flow process is disclosed. Also provided is a catalytic treatment and recirculation system for the vented gas which permits efficient use of oxygen within the system.

Abstract: Medium consistency oxygen delignification of pulp is carried out in a series of tubular reaction zones. Rapid delignification is achieved by agitating the pulp by rotating a timing screw in the first reaction zone at a speed in excess of 10 rpm, modifying the flights on the timing screw to increase the amount of agitation, or a combination of the two. Primary oxygenation is carried out in the first reaction zone while subsequent zones provide the retention time needed for the delignification reaction to go to completion. A thick stock pump is used to introduce the pulp into the first reaction zone.

Abstract: A treatment for wood chips in the manufacture of pulp is described. Prior to chip washing, the chips are placed in contact with an impregnation liquid such that all readily fillable cavities in the chips become filled with the liquid. The chips can be steamed prior to the impregnation process to increase the liquid absorption. After the impregnated chips are drained of the excess liquid, no appreciable amount of washing liquid is absorbed by them during a subsequent washing cycle used to remove included gravel and sand.

Abstract: The digestion of the cellulose-containing material is performed with a digestion liquor containing sulphur and sodium followed by recovery and regeneration of said digestion liquor and bleaching of the cellulose-containing material with chlorine dioxide. The SO.sub.2 -containing and possibly chloride-containing gas from the recovery boiler (11) of the process and from combustion of evil-smelling gases (20) is absorbed in an absorption liquor containing and alkali metal salt solution free of sulphur or sulphur compounds such as sulphide or thiosulphate, in a scrubber (27). The resulting scrubber liquor is mixed with acid residual solution (26) from the manufacture of chlorine dioxide, whereby sulphur dioxide (32) in gaseous state is returned to the process, whereafter the residual solution (34) free from SO.sub.

Abstract: Washed wood pulp from a continuous digester is treated with oxygen in the blow line from the digester. Most of the treatment occurs within the mixer. The mixer has a mixing zone with a swept area of 10,000 to 1,000,000 square meters per metric ton of oven-dry pulp. A preferred range is 25,000 to 150,000 square meters per ton of oven-dry pulp and an optimum range is around 65,400 square meters per metric ton of oven-dry pulp. Following mixing, the pulp may be taken to a subsequent process, a diffusion washer, or to a storage tank.

Abstract: There is disclosed a process for the transfer of fiber material from one circuit of circulating liquid to another, where the fiber material is transported by circuits positioned at right angles to the axis of rotation of a rotary transfer or feed valve and the circulating, transporting liquids are screened off through self-cleaning screens. The transfer valve contains a pocket and three working positions, a filling circuit, an emptying circuit, and an intermediate position for preheating the fiber material or providing a temperature lock depending upon the rotation of the pocket.

Abstract: In a reactor plant for treating finely divided bulk material an acid bulk material or pulp having a solids content of approximately 35-50% is conveyed to a combined high-consistency ozonizer and maturation reactor as a substantially vertical pulp column forming a gas blocking means. In the transition area between the ozonizer and the maturation reactor the finely divided and ozonized pulp which has a very acid pH-value is mixed with chemicals to a pH-value of approximately 8-11 and to a solids content of approximately 15-20%, at which solids content the alkaline pulp in the form of a continuously advancing column is subjected to a maturation process which terminates at a pH-value of the pulp of 6-7.

Abstract: A process for producing alkali pulp by using a single, cylindrical pressurized reaction vessel having therein a liquor-inpregnating zone, a cooking zone, a washing zone, and a diluting zone in that order, and having a motor-driven scraping or agitating device and a pulp discharging outlet in the end portion of the diluting zone. Alkaline aqueous medium containing dissolved oxygen therein is introduced into the diluting zone. A part of the introduced alkaline aqueous medium countercurrently contacts cooked cellulosic materials transferred from the washing zone to the diluting zone to proceed with oxygen-alkali delignification, and is finally discharged out of the vessel from the end portion of the cooking zone.

Abstract: Fibrous material is pre-steamed, impregnated with alkali liquor, refined, and then oxygen pulped at a low consistency (about 3 to 8 percent solids) using an alkali liquor which contains boron compounds. The pulping step of the process is carried out in stages with recycle of liquor to preceding stages after it has been reoxygenated. By recycling a major portion of the pulping liquor, the actual liquor to fibrous material ratio at each stage of the pulping step is maintained at a relatively high level (12/1 to 30/1) while the effective liquor to fibrous material ratio for the overall process is much lower (4/1 to 8/1). This results in a bright pulp of acceptable strength as well as a high solids content spent liquor which is economically recoverable.

Abstract: A process is provided for the chemical refining of cellulose pulp which comprises, in sequence, the steps of:(1) impregnating the cellulose pulp with refining chemicals in an amount selected to effect chemical modification of the pulp;(2) adjusting the pulp consistency to within the range from about 30 to about 70%; and(3) passing the pulp in turbulent flow through an elongated reaction zone from one end to another end thereof in a gaseous atmosphere consisting essentially of steam and preferably containing less than 1% by volume of oxygen at a superatmospheric pressure within the range from about 5 to about 400 kPa and a temperature within the range from about 100 to about 150.degree. C. at which the chemical modification proceeds without a mechanical working sufficient to change the degree of beating of the pulp by more than about 2.degree.