Abstract: A method and apparatus for the treatment of fiber suspensions of the pulp and paper industry, in particular, the so-called postscreening of pulp in the bleaching stage. The method includes that the pulp discharged from a bleaching stage is diluted to the screening consistency, that the pulp is screened in a pressure screen and that the accept fraction is supplied to the subsequent treatment stage at the supply consistency of the stage without a separate thickening stage. The screening is preferably carried out in a narrow-slot screen.

Abstract: A low-density hot melt adhesive is disclosed. Low-density filler, preferably hollow glass microspheres, is added to a hot melt adhesive to provide a hot melt adhesive having a specific gravity preferably between 0.7 and 0.93. The low-density hot melt adhesive is more effectively separated from cellulosic materials such as cardboard and kraft paper during recycling operations which separate contaminants such as adhesives from cellulosic fibers based upon the density of the adhesive.

Abstract: A process for separating printing ink from recycled paper fiber includes the steps of repulping recycled paper furnish with water in a rotary mixer for about 5 minutes at a consistency of 6% to 18% with a mixing element having a top speed no greater than 2,000 ft/min. This first stage repulping and mixing is followed by a second mixing stage of 20 to 45 minutes with a mixing element tip speed of 2,500 to 4,000 ft/min. Agglomerated contamination particles in the resulting slurry are removed by centrifugal cleaning and slot screening.

Abstract: A suspension containing fine and coarse particles is sprayed under high pressure by way of spray nozzles (10) against a rotating filter medium (7), so that the suspension is separated into a fine fraction, which passes through the filter medium and which contains said fine particles, and a coarse fraction, which does not pass through the filter medium and which contains said coarse particles. According to the invention the filter medium (7) is rotated by way of a drive motor (6) at a speed such that coarse particles and liquid developing on the side of the filter medium are removed from the filter medium substantially as the result of the centrifugal force the coarse particles and liquid are subjected to. In consequence the filter medium is efficiently kept clean during operation, which increases the capacity and improves the separation efficiency.

Abstract: A method for producing bleached sulfate pulp comprising the steps of:(1) conducting an initial bleaching of a sulfate pulp, wherein the pulp is manufactured by a sulfate process from softwood, with at least one non-chlorine-containing bleaching agent, the initial bleaching comprising one or more consecutive stages,(2) during step (1), lowering the kappa number of the pulp to below 12, while permitting the limit viscosity to fall below 900 cm.sup.3 /g,(3) fractionating the pulp prior to or at a time subsequent to step (1) to obtain:(a) a long fiber fraction comprising fibers, wherein less than 10% by weight of the fibers pass through 200 mesh and greater than 60% by weight of the fibers are retained on 30 mesh, wherein the long fiber fraction has a shive content of less than 0.

Abstract: A system for recovering fiber from sludge by-products generated in a pulp and paper mill. Initially, heavy materials are separated from a sludge flow, with the flow thereafter separated into first and second components. High grade fiber is recovered from the first component by centrifugal cleaners and also by optional fine pressure screens. The second component is forwarded to a refiner which breaks-down the second component to form a low grade pulp. In addition, after removal of the high grade fiber, remnants from the first component flow are forwarded to an additional separator such as a liquid cyclone, which removes sand, grit and ash, and thereafter the remnants of the first component can be sent to the refiner for forming a low grade pulp. Thus, the sludge is essentially separated into four components including: (1) high grade pulp; (2) low grade pulp; (3) heavy materials; and (4) sand, grit and ash.

Abstract: A method of removing fine contaminants from waste paper fibrous material (S) is described with solution (1) and pre cleaning (2) whereupon the fibrous material is first subjected to a washing treatment (3) and then to a flotation treatment (5). The washing filtrate (12) from the washing treatment (3) is cleaned in a filtrate-flotation treatment (4) so that a cleaned fraction (14) can be returned into the useful material (13) of the washing treatment. The so cleaned waste paper fibrous material can be passed to further treatment steps such as flotation, bleaching and/or dispersion. The reject material from the filtrate-flotation (4) is, in one embodiment, again subjected to a flotation treatment.

Abstract: An apparatus for separating out the contaminants in a pulp slurry in which the housing of the separator is divided by a perforated screen into an inlet and an outlet section. The inlet section of the separator has a rotating blade mixing means to propel the liquid mixture in the pulp slurry away from the screen and toward the housing wall. The outlet section of the separator has a rotating blade cleaning means which is adjacent the downstream side of the screen for removing contaminants from the upstream side of the screen and moving the removed contaminants into the inlet chamber for further mixing and removal therefrom.

Abstract: Cellulosic pulps of selected fiber morphology are disclosed having a coarseness less than a threshold coarseness level. The threshold coarseness level is a function of average fiber length. The cellulosic pulps are especially useful for producing paper structures such as tissue paper. A method for producing the cellulosic pulps is also disclosed.

Abstract: A process is disclosed for deinking pulp which has been made from paper printed with flexographic ink. The process uses a surfactant component made from a fatty acid or a fatty acid blend and at least one alkoxylated diamine selected from Formula I: ##STR1## where X, Y, W and Z may be alike or different and are each independently selected from the group consisting of(i) --(CH.sub.2 --CH(CH.sub.3)--O).sub.a (CH.sub.2 --CH.sub.2 --O).sub.b --;(ii) --(CH.sub.2 --CH.sub.2)--O).sub.c (CH.sub.2 --CH(CH.sub.3)--O).sub.d --; and(iii) random copolymers of ethylene oxide and propylene oxide,wherein a, b, c and d are each selected independently to be a number between 1 and 30 so as to give an HLB value between 5-15.

Abstract: White water from a paper machine is treated in an improved fiber recovery process, i.e., the "save-all" process. Prior to the mixing of sweetener stock into the white water the sweetener stock is fractionated (undiluted) into fine and coarse fiber fractions, of which only the coarse fraction is fed as sweetener stock into the white water. The inlet line for the sweetener stock is provided with a fractionation apparatus for removing the fine fraction from the sweetener stock. Treatment apparatus may also be utilized to separate the white water into fine and coarse fractions before passing the fine fraction to a mixer for mixing with the sweetener stock coarse fraction.

Abstract: The invention concerns the recycling of waste paper in a deinking process with flotation with at least one other cleaning stage downstream. According to the invention, selective flotation is performed in multiple stages. After no more than a third flotation stage, the flotation foam collected up to that point is removed and purified by means of flash flotation, which produces sludge, clear water and separated foam that contains the contaminants from the waste paper feed. Subsequently, the sludge is removed from the paper recycling process. Large impurities are removed from the sludge (foam) (except for the foam from up to the three last stages) in up to two washing units (including thickeners) or screen units. The fibers are then separated from the relatively fine contaminants, and these contaminants are primarily removed as sludge from the resulting low-fiber fractions by flash flotation.

Abstract: An appliance for sorting and deflaking fiber suspensions has a rotor with a horizontal axis rotatively mounted in a housing. In a first, inlet rotor zone the rotor is provided with entraining means for extracting by centrifugation contaminating particles of high relative density. The rotor is surrounded donwstream by a screening cylinder and is also provided with entraining means for the fiber suspension, which deflake and sort out the fiber suspension in a second rotor zone. In a third rotor zone the fibers are washed out of the rejects after water has been added and in a fourth zone the rejects are dehydrated.

Abstract: A process for deinking wastepaper by combining a water-miscible organic solvent with inked paper to create a solvent/paper slurry, agitating the solvent/paper slurry to assist in releasing ink from the paper, separating the ink-ladden solvent from the paper, and washing residual ink and solvent from the paper.

Abstract: A method for removing ink from printed paper to be recycled by pulping the printed paper to be recycled with water to produce a paper pulp slurry with a consistency of between about 1% and about 20%, adjusting the pH of the paper pulp slurry to between about 6 and about 13, maintaining the paper pulp slurry at a temperature of between about 30.degree. C. and about 100.degree. C., adding an agglomerating agent to the paper pulp slurry, pulping the paper pulp slurry for a period of between about 5 min. and about 90 min., such that the ink particles agglomerate, thereafter, adding between about 0.2 wt. % and about 2.0 wt. %, based on the dry weight of the pulp, of talc to the paper pulp slurry, and thereafter, removing the agglomerated ink particles from the paper pulp slurry.

Abstract: An apparatus for treating pulp includes an outer casing, a stationary screen surface mounted in the outer casing. A conduit introduces pulp into the interior of the screen surface. An annular space is defined between the screen surface and the casing for receiving the fraction passing through the screen surface. A feed screw is rotatably mounted in the interior of the screen surface. The feed screw extends vertically or is to some extent inclined relative to the vertical direction. The feed screw includes a shaft and pulp conveying blades. The periphery of the feed screw is provided with a nozzle conduit extending substantially parallel to the shaft and located close to the screen surface for spraying washing liquid to the screen surface. The apparatus is especially suitable for screening and/or thickening of fiber suspensions in the wood processing industry.

Abstract: The invention concerns a process for the treatment of wastepaper, carried out for the most at a high consistency of at least 13% in the first stages, beginning the dissolution (soaking) and including a coarse sorting stage. The invention is characterized in that in the case of wastepaper containing a share of at least 40% of deinking wastepaper provided with printing inks the three first process stages, namely in this order of soaking, coarse cleaning and the further extensive dissolution of the wastepaper, take place at a considerable reduction of the wastepaper shreds to the usual speck size at a consistency of at least 13%, and the soaking under considerable addition of dissolving chemicals, and that the wastepaper including essentially all heavy contaminations, such as part of wood, glass, plastic or metal contained in the wastepaper, including pieces of metal straps of the wastepaper bales, is fed to the process.

Abstract: A process for the production of a papermaking filler product from the fiber fines/clay fraction of a pulp, paper, paperboard, or deinking mill waste solids such process comprising the reaction of said solids with sufficient acid to lower and maintain a pH of less than 5.0. Such process yields improvement in the drainage characteristics of the material. Bleach can be added or the pH raised back to neutral to further improve the specific resistance and/or brightness of the material.

Abstract: A method of pulping baled waste material includes breaking up the bale and applying the broken bale to a fluffer or shredder to form a fluffed waste paper product containing heavy and light contaminants. This product is applied to an air separator from which heavier non-paper contaminant fraction is removed, and the remaining product is applied to the inlet of a vortex separator which removes a light reject fraction. A second accepts fraction is then water soaked and applied to the inlet of a series of drum-type pulpers. The invention further includes a drum-type pulper in which an axial shaft has radially-extending arms or buckets which dip into a pool of stock from waste paper in which the buckets sweep the interior of the drum, lift a quantity of the mixture from the pool, and allow the same to drop back into the pool. Vanes on the buckets cause the mixture to move axially in the drum from an inlet to an outlet.

Abstract: A method and an apparatus for separating heavy impurities from a fiber suspension include a centrifugal pump capable of separating heavy impurities towards the periphery of the interior chamber of the pump. The fiber suspension is caused to rotate in the interior chamber so as to urge the suspension downstream as well as separate the impurities towards the periphery of the chamber where they can be collected.

Abstract: A method of obtaining an excellent recycled pulp from waste pressure-sensitive adhesive paper which has previously been discarded. This method being characterized in that the waste paper is defiberized, then a defiberized suspension thereof is diluted, the diluted suspension is coarse screened by a screen having a slit width of below 0.5 mm, the pulp suspension after coarse screening is dewatered so as to have a solid matter consistency of 15 to 40% by weight, the dewatered stuff is mechanically agitated, the difference between the temperature of the stuff before the agitation and the temperature thereof after the agitation being below 12.degree. C., the obtained stuff is being diluted again, the diluted suspension is fine screened by a screen having a slit width of below 0.

Abstract: A novel process for the treatment of wastepaper which provides for enhanced removal of both ink particles and non-ink contaminants is disclosed.

Abstract: A method an apparatus for treating waste, such as domestic garbage, industrial waste and the like, in which the waste is suspended in a liquid such as to obtain a slurry or a pulp. The constituents of the pulp or slurry are separated into different fractions in accordance with their density and/or magnetic properties or like features. Subsequent to having sorted (18, 24, 26) and removed objects from the pulp or slurry, the pulp or slurry is fed to a wet dryer (32) in which the pulp or slurry is kneaded. As a result, the composite material is separated into its respective constituents; for instance, plastic coatings are separated from their respective substrates, such as paper. The pulp or slurry is washed (36) downstream of the wet grinder (32), in order to remove plastic debris (40). The thus obtained fibre suspension is then led away for further treatment (44) or use. When producting the waste/liquid suspension, the suspension is heated to a temperature of at least 60.degree. C.

Abstract: A flow management system and process for providing controlled separation and sizing of an incoming flow of wood chips. A flow management screen is provided in the form of a horizontal disk screen having a variable speed drive, with the drive controlled based upon the flow rate of wood chips to the screen. By controlling the rotational speed of the disks of the horizontal disk screen, the flow separation and sizing to subsequent screening stations can be predicted and controlled. As a result, more consistent output is provided, as well as improved system efficiency and ability to accommodate for varying operational conditions and wear.

Abstract: A fibre suspension is separated by a filter device having a hollow filter body (1) with a wall (2) of filter material, and a container (3). The entire fibre suspension to be separated is sprayed in the form of at least one liquid jet onto said wall (2) to force a fine fraction of the suspension containing most of said undesired particles through said wall of filter material into the hollow filter body, thereby leaving a created coarse fraction of the fibre suspension mainly containing fibres in the container outside the filter body. Relative displacement between the liquid jet and the filter material is provided. Said created coarse fraction is dewatered through the wall of filter material, and said dewatered coarse fraction is discharged from the container.

Abstract: A method and apparatus for reclaiming cellulosic fibers from a bale containing waste papers, in which the bale is positioned in a treatment enclosure, and the enclosure is placed under a vacuum. A treating fluid is drawn into the enclosure, which penetrates the bale interior spaces, and produces a preferential swelling of uncontaminated cellulosic fibers. After the treating fluid is withdrawn from the enclosure, a slurrying fluid is passed through the bale contents, to form a fiber-fluid suspension slurry.

Abstract: A method and apparatus for depithing bagasse fibers wherein a horizontal perforate surface such as a screen is provided with means for delivering bagasse onto a delivery end and the screen is given sudden vertical accelerations to accelerate the bagasse upwardly separating the pith from the fibers and driving the pith down through the perforations with the accelerations repeated at sequential localized areas along the screen.

Abstract: An apparatus for processing wood chips for use in the preparation of pulp in a papermaking operation including a conduit for accommodating a flow stream of wood chips, a rotary valve in the conduit, shunt branch conduits with a first shunt leading to a chip dumping bin and a second shunt leading to a chip processing device; dampers in the branches with the damper for the first shunt branch being in normally closed position and a damper in the other shunt branch being in a normally open position; and a metal detection device upstream of the branches operative to move the first damper to open position and the second damper to closed position for a predetermined time and to stop the rotary valve and to reactivate the dampers and rotary valve after a predetermined time.

Abstract: A pressure sorter for a suspension flow includes a cylindrical housing having at least one inlet opening and at least one outlet opening with a defined pressure drop therebetween. A rotationally symmetric screen basket defining an axis is disposed within the housing. The screen basket has a plurality of openings defining a total screen perforation passage area. The axis of the screen basket is positioned offset a distance of 6 to 12% of the diameter of the screen basket. The axis of the screen basket is disposed in a plane which extends through the housing axis and is perpendicular to the housing outlet opening. A rotor and suspension sorting space are disposed centrically within the screen basket. An accepts space is disposed radially outward of the screen basket between the screen basket and the housing.

Abstract: A method of separating an aqueous solids containing suspension includes (a) subjecting a first solids containing suspension to centrifugal forces so as to separate the suspension into a first gas containing flow, a second gas-free flow and a third flow; (b) feeding the third flow into a flotation cell having a bottom; (c) introducing air at the bottom of the flotation cell into the third flow for separating from the third flow a fourth partial flow; (d) withdrawing the air containing third flow after the separation of the fourth partial flow from the flotation cell; and (e) subjecting the third flow to the centrifugal forces of step (a).

Abstract: The invention relates to a process for the removal of fillers from waste paper, after floatation of the printing ink, in the presence of at least partly water-soluble polymers and/or copolymers having number average molecular weights of 1,000 to 500,000 by flotation.

Abstract: Deinking of printed paper is accomplished by repulping printed wastepaper in an aqueous medium containing a deinking chemical. The presence of the deinking chemical causes initial agglomeration of ink particles to produce an ink pulp medium. Agglomerated ink particles are removed from the ink pulp medium by size and density separation procedures to separate coarse ink and produce a fine ink particle stream. The fine ink particle stream is recirculated to cause additional agglomeration of ink particles. The reagglomerated ink particles are removed from the fine ink particle stream by size and density separation procedures to produce a substantially ink free pulp medium. The invention provides agglomeration processes with high ink removal from printed paper.

Abstract: Devices for screening pulp suspensions are disclosed including a cylindrical screen extending longitudinally within a housing, an inlet for feeding the pulp suspension into the interior of the cylindrical screen, an accept outlet for removing the accept portion of the pulp suspension after it has passed through the cylindrical screen, a reject outlet for removing a reject portion of the pulp suspension at the opposite end of the cylindrical screen with respect to the inlet, and a rotor concentrically positioned for rotation within the cylindrical screen such that an annular screen chamber is created between the rotor and the screen, the rotor including wings extending from its exterior such that the wings have a length circumferentially with respect to the rotor which ranges from about 2:1 to about 6:1 with respect to the distance between the rotor and the screen, and the leading edges of the wings being separated a greater distance from the rotor than the trailing edges of the wings.

Abstract: Cellulose pulp compositions of selected fiber morphology are disclosed. Of particular interest, are morphological forms of wood fibers with the potential to achieve improved paper strength without suffering the penalty of slow drainage rate. These cellulose pulps are especially useful for efficiently producing paper structures such as tissue paper of requisite strength.

Abstract: First and second washing machines are utilized to recycle plastic and cellulose from disposed diapers. The disposed diapers are loaded into the first washing machine and, while being agitated, are washed in water, alkali and soap. During washing, the cellulose becomes separated from the plastic. The cellulose is drained out of the first washing machine with the water, leaving the plastic in the first washing machine. The plastic is then cleaned in the first washing machine. A pump transfers the cellulose and water to the second washing machine. In the second washing machine, the cellulose is washed in alkali and soap while being agitated. The second washing machine has a screen for retaining the cellulose therein, while passing the water and waste material.

Abstract: Screening apparatus for separately removing knots and heavy reject particles from paper making stock comprises a generally cylindrical vertical housing having the interior thereof separated by a cylindrical perforated screening member into an annular screening chamber and an accepts space on the outer and inner sides of the screening cylinder respectively. Separate outlets for light and heavy reject particles are located at the top and bottom of the screening chamber, the supply flow of feed stock enters the screening chamber at the bottom thereof, and special provision is made to insure that maximum separation of the knots and other lighter reject particles from the heavy reject materials will be effected within the screening chamber with minimum contact with the screening cylinder itself.

Abstract: A method and apparatus for improving the treatment of a gas containing fiber suspension in the pulp and paper industry, especially for increasing the capacity of a screening department, a washing department, a thickening department, a press, a curved screen, or the like, includes the simultaneous separation and removal of the gases prior to the respective treatment stage.

Abstract: A method for removing laser printer and xerographic toner, ink or the like from paper to be recycled comprising pulping the paper to be recycled with water to produce a paper pulp slurry with a consistency of between about 1% and 20%, adjusting the pH of the slurry to between about 6 and about 13, adding between about 0.3 and about 5.0 wt. %, based on the dry weight of the paper, of a surfactant to the slurry, the surfactant having the formula R.sup.1 --R.sup.2 --R.sup.3, wherein R.sup.1 and R.sup.3 are each selected from the group consisting of rosins, rosin dimers and mixtures of rosins and rosin dimers and R.sup.2 is a polyethylene glycol (PEG) having a molecular weight of between about 220 and about 660 Da, and adding between about 0.01 and about 5.0 wt. % of polyacrylic acid to the slurry, maintaining the slurry at a temperature of between about 30.degree. C. and about 120.degree. C.

Abstract: A screen aperture blinding prevention and liquid overflow prevention and level control apparatus for a knot drainer senses liquid level within the knot drainer and compares the sensed level to a setpoint level. Differences in the two levels generate control signals of appropriate magnitude and direction, and those control signals are transmitted to a valve whose degree of responsiveness and openness is adjusted to change the outflow rate of accepts liquor from the accepts chamber of the rejects separator. In addition, passive level control is provided in the discharge line for establishing accept flooded screen apertures regardless of variations of inflow and outflow rates during operation while active level control to create accept flow rate greater than, less than, or equal to inlet flow rate is provided by the combination of siphonic loop, barometric leg and control. Continuous flow of fiber and liquid through separating screen apertures is appropriately supervised by monitoring accepts chamber pressure.

Abstract: A screening system incorporated into the system of sawdust collection for paper producing pulp. An upper and lower range of the sawdust particles is designated as between smaller, strength-inhibiting size particles and larger strength-enhancing size particles. A screen is provided to screen out the smaller size particles. The screen is made out of stainless steel to avoid rusting and corroding and also to more readily pass the moistened smaller size particles. The screen is sloped and agitated to induce shuffling of the sawdust mixture, the process of which results in a separation of about 50% of the particles as rejected smaller size particles and 50% as acceptable larger size particles desirable for paper producing pulp.

Abstract: The present invention relates to a method and an arrangement in a fibre reclaimer for cleaning of heavy and light contaminate particles from a fibre suspension and said fibre reclaimer comprises at least a vessel (4) having an opening (15) which via a connection arrangement (1, 2) is connectable to a cyclone. The connection arrangement consists of a cone (1) having an outlet (13) with a predetermined diameter (d) and is inserted and located in a conical mantle (2), which with its free end part (14) is fixed to the opening (15) of the vessel (4), whereby the opening (13) is situated a predetermined distance (A) from the opening (15).

Abstract: A method and apparatus for enhancing knot transport in a knot drainer has a provision for decreasing tangential velocity of the feed slurry in the inlet chamber, a hydrodynamic force reduction provision in the screening chamber, and a provision for increasing the ratio of circumferential friction forces to axial friction forces in a housing extension above the screening chamber. This drastically reduces frequency of knot transport interruptions which would otherwise occur in the knot drainer, thereby improving knot drainer performance efficiency.

Abstract: A method for thickening a liquid suspension of solid particles, such as papermaking pulp in water, uses a pair of spaced apart rolls and a woven wire or plastic wire belt trained around these rolls. The suspension is supplied at the first roll for centrifugal extraction and is carried by the belt to the second roll for further water extraction and thickening, and is then discharged from the apparatus. In one embodiment, the first roll is formed with an open surface, and the suspension is delivered to the web at least partially by flowing both into and out a roll chamber via the first roll openings, from a headbox in the on-running wedge zone.

Abstract: A stock liquid is made to flow into a cell through a stock inlet at one end of the cell. The stock liquid is admixed with air bubbles from an air bubble generating device disposed at a lower portion of the cell and extending between the opposite end plates of the cell, thereby forming the stock liquid into a spiral flow. Ink particles are entrapped by the air bubbles to deink the stock liquid and the air bubbles remain as froth over the free surface of the stock liquid. The froth is made to flow down to the froth trough. The deinked stock liquid is discharged to the exterior of the cell through the stock outlet at the other end of the cell.

Abstract: A method is provided for separating fibers from a solid sample which includes a solid material having fibers embedded therein. A first chamber, containing the sample, and a second chamber are defined within an appropriate vessel(s) such that the first chamber is positioned generally above the second chamber, and a filter is positioned between the chambers. At least one conduit, having at least one valve associated therewith, is further provided which is in fluid communication with the second chamber. Closure of such valve(s) substantially seals the second chamber except for fluid communication of the second chamber with the first chamber through the filter.

Abstract: An apparatus for treating a pulp suspension in a screening plant of a pulp mill wherein impurities are separated from defibered pulp by screening and/or cleaning, the cleaned pulp is thickened, the impurities are further treated in the screening plant by screening and defibering the accept fiber material for further screening and thickening and further impurities are removed from the screening plant after various screening stages, the apparatus including means for effecting one or both of the pulp screening and cleaning stages in a closed, pressurized space in the screening plant and preventing the access of air to the pulp treated by effecting the thickening stages in a pressurized state and at the initial pressure of one or both of the preceding screening and cleaning stages.

Abstract: The invention relates to a method and a device for screening and treating pulp. In the invention, the pulp is screened in a screen into an accepted fraction and a rejected fraction, the rejected fraction being treated after the screening by removing water from it. In order to reduce the energy consumption of the refining process, the rejected pulp fraction is screened by means of a means (13) rotating rapidly in a reject space (12) of a screen (1) in such a manner that the rapidly rotating means (13) effects a radial flow of the fine-grained material contained in the rejected fraction outwards through a perforated wall (14) surrounding the rotating means (13) into a space (15, 15a) from where the fine-grained material is discharged.

Abstract: Methods for producing mechanical pulp are disclosed including impregnating softwood chips with water and a complexing agent, refining the impregnated chips in a first refining step including a double-disk refiner, fractionating the refined softwood pulp to produce a reject portion comprising beteen about 15 and 35% of the refined pulp and including an increased concentration of the long and stiff fibers therein, refining the reject portion in second and third refining steps in which the second refining step employs a greater concentration of pulp than does the third refining step, and fractionating the refined pulp.

Abstract: In apparatus and methods for preparing deinked paper making stock, the initially pulped and cleaned stock is fractionated by filtering through a continuously moving mesh belt of a predetermined mesh size which will retain substantially all of the fibers of greater than a predetermined length as a first suspension fraction and a second suspension fraction comprising the majority of the liquid component of the feed suspension along with small contaminant particles and the remaining fines. These two fractions are then treated separately by bleaching the first fraction and recovering the fines from the second fraction, after which the fines and the first fraction are recombined for further treatment and use.

Abstract: The fibers of recycled paper are cleaned by agitating the slurry containing the fibers to maintain the fibers in suspension, and contacting the slurry with wash water to remove ink and other contaminants. The apparatus includes a passageway having screens forming opposite sides of the passageway. Agitators are within the passageway, and create enough turbulence to prevent fibers from settling or agglomerating. Channels adjacent to each screen carry wash water, and pump pressure creates a pressure differential across the screens to cause the wash water to contact the slurry and to be removed from the passageway.