Abstract: There is a need for a cheaper method of producing bleached TMP and CTMP without impairing the properties of the pulp.

Abstract: The object of the present invention is a method for making mechanical pulp, such as thermomechanical or chemi-thermomechanical stock. The mechanical pulp is utilised as a raw material for printing paper, and its freeness value is 30—70 ml CSF. According to the method, the refined stock is screened in several stages into accept and reject stock portions. The stock is screened at a consistency of not less than 10%.

Abstract: This invention provides a dried singulated crosslinked cellulose pulp fiber product as well as an apparatus and a method for forming singulated, crosslinked, and dried fibers. In accordance with the process, a feed pulp containing a crosslinker is delivered to a jet drier. The jet drier singulates and dries the feed pulp. The singulated and dried fibers are collected from the jet drier. The feed pulp may be further treated with a treatment substance. The jet drier may be maintained at negative pressure. The product fibers may have low knot count, a low fines count, as well improved kink, curl and twist. The apparatus for carrying out the process may include a pretreatment station for supplying the treatment substance, a pulp feed device designed for pulp, a pulp feed device designed for pulp and foam suspensions, and/or a fiber separation station having a vacuum conveyor.

Abstract: This invention provides a dried singulated cellulose pulp fiber product as well as an apparatus and a method for forming singulated and dried fibers. In accordance with the process a feed pulp is delivered to a jet drier. The jet drier singulates and dries the feed pulp. The singulated and dried fibers are collected from the jet drier. The feed pulp may be treated with a treatment substance. The jet drier may be maintained at negative pressure. The product fibers may have low knot count, a low fines count, as well improved kink, curl and twist. The apparatus for carrying out the process may include a pretreatment station for supplying the treatment substance, a pulp feed device designed for pulp, a pulp feed device designed for pulp and foam suspensions, and/or a fiber separation station having a vacuum conveyor.

Abstract: A fiber suspension is produced from waste paper by first filling a pulper with a batch of the waste paper. The pulper is operated to partly defibrate the batch of waste paper substantially without disintegrating coarse imputities into finer impurities. The partly defibrated batch of waste paper is separated into a coarse reject fraction and an initial fiber suspension containing some waste paper fragments and fine impurities. The initial fiber suspension is pumped through a rotary screen apparatus provided with a tubulat fine screen and a pulper type impeller rotating coaxial with the tubular screen, but devoid of any impeller co-operant extraction plate, to defibrate waste paper fragments remaining in the initial fiber suspension and to separate the initial fiber suspension by means of the tubular fine screen into a fine reject fraction containing fine inpurities and a complete fiber suspension substantially free from impurities.

Abstract: The invention relates to a method for separating hemicelluloses from a biomass containing hemicelluloses. Said method comprises the following steps: a) the hemicelluloses are extracted from the biomass containing hemicelluloses by means of treatment with a complex compound in an aqueous solution, forming a soluble hemicellulose complex, and b) the complexed hemicelluloses are separated from the biomass. The inventive method is especially suitable for producing high-quality chemical conversion pulp from raw cellulose. Not only does the inventive method enable the obtained products to have a high degree of purity, but it is also extremely economical and causes few emissions. The inventive method is also characterised in that polymer hemicelluloses in a pure form can be obtained as by-products.

Abstract: A method of making bleached mechanical pulps is disclosed for pulping mills having a primary and a secondary refiner. A first step is to provide cellulosic materials, such as wood chips to refine into the pulp; the wood chips have an initial brightness level. A second step is to provide a bleaching liquor to the refining system of the pulp mill, wherein the liquor comprises an amount of hydrogen peroxide and an amount of alkali having greater than 0% to 100% magnesium hydroxide or soda ash or a combination thereof. A third step is to hold the pulp with the bleaching liquor at a temperature in the range of about 85° to about 160° C. and for about 2 to about 180 minutes. The components of the bleach liquor can be added at the first refiner or interstage between refiners.

Abstract: The invention relates to a method of mixing pulp components in the manufacture of paper, in which method the pulp components to be mixed are led to a mixing point along tubes arranged inside each other. The pulp component flows are mixed by generating turbulence in them by means of the end of an inner tube, the cross-section of which end is wave-like. This turbulence is guided and its effect is intensified by means of form parts in connection with the mixing point, which form parts are arranged on the inner surface of the outer tube. Further, the invention relates to an arrangement implementing the mixing of pulp components in accordance with the method.

Abstract: A method for producing chemical pulp from cellulosic material by means of alkaline cooking, including cooking the material to pulp at cooking temperature in a digester, reducing the temperature at the end of the cook, substantially relieving the overpressure in the digester and then discharging the pulp from the digester by means of pumping. The method is characterized in that the pulp is cooled to essentially 85° C. to 70° C. before pumping cooked material as a fluid suspension from the digester, and that the temperature of the cooked material is maintained in the same temperature range and at a pH level being between 10 and 13, between the digester and a first delignification/bleaching stage, thus avoiding mechanical damage of cellulosic material.

Abstract: The present invention describes a method for removing contaminants from a recycled paper fiber slurry comprising adding a cationized mineral to the paper fiber slurry to form complexes between the cationized mineral and the contaminants and separating the complexes from the paper fibers.

Abstract: A method of manufacturing a multi-purpose functional agricultural mulching paper is disclosed. The method comprises steps of (a) providing a papermaking material, (b) treating the papermaking material to form a cleaned paper pulp, and (c) adding at least one functional additive into the cleaned paper pulp and treating the cleaned paper pulp to form the multi-purpose functional agricultural mulching paper. The multi-purpose functional agricultural mulching paper of the present invention can be applied in week control, pest control, bacterial control, plant disease control, growing seedling, fertilizer supply and seed sowing to increase the economic benefits.

Abstract: A method of selecting bulk wood units for mechanical pulping, which consists of establishing a reference scale by selecting a test sample measuring the acoustic velocity through each sample unit, selecting acoustic velocity band from the sample results, processing the sample units using known mechanical pulping processes, testing the resulting pulp to measure the freeness of the pulp, and then graphing the pulping energy measurements against the pulp freeness measurements for each of the velocity bands to produce a reference scale; measuring the acoustic velocity through each of the units, comparing the velocity measurement for each unit against the reference scale, and then dividing the tested units into subgroups according to the predicted mechanical pulping energy.

Abstract: Rotor for a paper stock processing machine, an anti-wear element for protecting a leading front surface of a rotor blade, and a paper stock processing apparatus. The rotor includes at least one rotor blade having a leading front surface to be protected, and an anti-wear element comprising a base body and at least one wear-resistant surface. The anti-wear element is coupled to the leading front surface. The anti-wear element includes a base body with a back side, and at least one wear-resistant working surface. The back side is formed to correspond to a shape of, and to be coupled to, the leading front edge. The apparatus includes a tank, a screen, and a rotor rotatably coupled adjacent the screen. The rotor includes at least one rotor blade having a leading front surface, relative to a rotational direction of the rotor, and an anti-wear element coupled to the leading front edge. The anti-wear element includes a base body and a wear-resistant working surface.

Abstract: The invention relates to a method of controlling quality of pulp. Pulp formed in mechanical defibering of wood is screened into at least two fractions, the accept that has passed the screening phase being forwarded for further use and the reject that did not pass the screening being removed from the screening phase. The invention comprises determining flow amount and consistency of the pulp supplied to the screening phase and, correspondingly, of the reject removed therefrom, and calculating a passage ratio of the reject and the supplied pulp by means of the flow amounts and consistency values verified through the measurement, and adjusting the screening phase according to said passage ratio.

Abstract: The invention concerns a method and equipment for pulp fractionation in a paper or board machine. In the method, virgin stock is conducted to the paper or board machine and further to a centrifugal cleaner installation (12) into its first centrifugal cleaner step (12a1). From the first centrifugal cleaner step (12a1) the accept is conducted into a multi-layer headbox (10) to form a layer of the web determined according to the concerned fraction. From a second step (12a2) and/or from lower steps (12a3, 12a4 . . . 12an) of the centrifugal cleaner installation (12) a second fraction or more fractions are conducted into the multi-layer headbox (10) to form a second layer or other layers of the web, which are determined according to the pulp fractionation taking place in the concerned second step or lower steps.

Abstract: The invention relates to a method, an apparatus and a screen for screening mechanical fibre pulp. According to the invention a short fibre material is separated using a gap screen, whereby said material can be very efficiently separated to form a specific fraction.

Abstract: The invention relates to a method and a screen for screening two or more pulp mixtures with different roughness. The screen comprises a first screen cylinder and a second screen cylinder. A coarse first pulp mixture is fed into the inlet end of the first screen cylinder, and a second, less coarse pulp mixture is supplied to the second screen cylinder. The pulp mixtures are screened by means of a screen surface of the screen cylinders into accept that passes apertures provided in the screen surface and reject that does not pass the apertures. The accept from the second cylinder is conveyed by means of a guide tube provided between the cylinders towards the inlet end of the first cylinder and it is finally mixed with the first pulp mixture. The accept from the first and the second pulp mixture passes the screen surface of the first screen cylinder.

Abstract: A fiber mat is formed on a screen cylinder of a pressurized fiber filtering device used to filter particles from a liquid stream. The fiber mat is a fine particle filter to remove small particles from the liquid stream. The fiber mat is formed by injecting cellulosic fibers into the liquid stream flowing into the fiber filtering device. These fibers collect on the screen cylinder as the liquid flows through the cylinder. The collection of fibers forms the fine filtering mat.

Abstract: Pressurized screen to remove contaminants from a contaminant-containing fibrous paper suspension. Pressurized screen includes a housing, a first screen element, essentially axially symmetric and rotatably mounted within housing, and a second screen element, which is essentially axially symmetric. First and second screen elements are successively arranged in suspension flow direction. At least one intake, coupled to housing, supplies suspension to housing, and at least one accepts outlet, coupled to housing, conveys a part of suspension that passes through the second screen element out of housing. At least one coarse reject outlet is located within housing to remove a part of suspension not passing through first screen element, and at least one fine reject outlet is located within housing to remove a part of suspension not passing through second screen element. First screen element includes conical shape with opening angle (&agr;) between about 10° and 170°.

Abstract: The invention relates to a process for directing a papermaking pulp towards a regulated outlet (9). Accept from successively arranged cleaning stages (6, 14, 20) is lead towards the outlet (9), while the respective rejects are lead to the inlet of the succeeding cleaning stage (14, 20). Depending on the operational situation, the accept from the cleaning stages (6, 14, 20) is totally or partly lead towards the outlet (9) while excess accept is lead in the opposite direction to the inlet (5) of the preceding cleaning stage (6). The invention also relates to an arrangement for the feeding of a forming wire, wherein a collecting accept pipe (8) is provided for extending between the outlet (9) and a feeding (3) for fresh pulp, while reject pipes (11, 18) lead to the next cleaning stage (14, 20).

Abstract: A method and apparatus treat fiber based material so as to reduce the loss of mineral fractions in the treatment of broke in paper production. Broke is a reusable raw material from a paper machine that contains mineral fractions which are desirably returned to the process as a raw material. The material containing minerals is dispersed into broke pulp, which is fractionated, and the accepts from the fractionation are returned to the paper manufacturing process providing for efficient and economical recovery of the minerals in broke. The mineral fraction provided in the rejects from the fractionation is treated separately before it is reused as filler or coating material in the production of paper or board.

Abstract: A screen, for screening material used in the production of paper, board and the like, having a screen basket and a rotor supporting several blades which can be moved along the wall of the screen basket when the rotor rotates. The blades having a convex curvature on the side facing the screen basket. The radial clearance between the surface of the blade facing the screen and the screen being lowest between the front sector, viewed in the direction of rotation, and increasing towards the rear edge of the blade.

Abstract: A device and process for aerating dispersions, particularly for flotation of pulp suspensions, in a de-inking process where the pulp suspension containing dirt particles is sprayed into a tank together with air. The air is injected at a minimum of two successive points and mixed with the suspension.

Abstract: Processes and systems are provided for cooking wood chips containing knots in a digester to produce a chemical pulp. Specifically, a low pressure slurry of comminuted cellulosic fibrous material is formed in a vessel operating at essentially atmospheric pressure by mixing therein a liquid and the comminuted cellulosic fibrous material. The low pressure slurry is thereafter supplied to a low pressure inlet of a high pressure transfer device while liquid is removed from the slurry through a low pressure outlet thereof. A high pressure liquid is supplied to the transfer device (e.g., via a slurry pump) so as to form a high pressure slurry of the comminuted cellulosic material which is then discharged from a high pressure outlet of the transfer device. Knots are removed via a knot separator from a slurry of undercooked knot-containing cellulosic material at essentially atmospheric pressure.

Abstract: Processes and systems are provided for cooking wood chips containing knots in a digester to produce a chemical pulp. Specifically, a low pressure slurry of comminuted cellulosic fibrous material is formed in a vessel operating at essentially atmospheric pressure by mixing therein a liquid and the comminuted cellulosic fibrous material. The low pressure slurry is thereafter supplied to a low pressure inlet of a high pressure transfer device while liquid is removed from the slurry through a low pressure outlet thereof. A high pressure liquid is supplied to the transfer device (e.g., via a slurry pump) so as to form a high pressure slurry of the comminuted cellulosic material which is then discharged from a high pressure outlet of the transfer device. Knots are removed via a knot separator from a slurry of uncooked knot-containing cellulosic material at essentially atmospheric pressure.

Abstract: Process and container for stacking and diluting paper fiber stock. The process includes stacking a high-consistency stock in a first volume for defined dwell time, conveying stock to second volume arranged to adjoin downstream first volume, diluting stock in second volume at least to a pumpable consistency, and drawing off diluted stock as suspension through a wire. Process includes generating circulation flow in second volume, such that circulation flow facilitates conveying of stock located on boundary of first volume into second volume, diluting stock, and drawing stock through wire. Process includes rotating rotor to keep wire clear, and generating, with screw coil arranged directly in front of rotor, flow that runs in axial direction of screw coil and guides diluted suspension away from wire. The instant abstract is neither intended to define the invention disclosed in this specification nor intended to limit the scope of the invention in any way.

Abstract: A method of dispersing hydrophobic particles in aqueous suspensions comprising adding to the suspension an effective amount of an ethylene oxide-propylene oxide block copolymer, wherein the copolymer has a molecular weight of from about 1,000 to about 50,000 and a HLB of from about 1 to about 4 and compositions comprising the ethylene oxide-propylene oxide block copolymer.

Abstract: A screen, such as a drum screen or a flat screen, for screening or fractionizing pulp suspensions or the like suspensions of the pulp and paper industry. The screen comprises a reinforcement attached to the surface of the screen plate, such as a reinforcing ring (16, 18) attached to the surface of a drum screen (10). The reinforcement (17) is made of fiber-reinforced composite material. The invention also relates to a method of manufacturing the reinforcement of a screen plate of composite material. The composite material is preferably made of reinforcing fiber and plastic matrix material.

Abstract: Method for manufacturing paper or cardboard in one or more plies in order to achieve a paper or cardboard product with an even quality. The method comprises determining a fiber composition of a broke paper or cardboard waste broke, fractionating the broke; and conveying at least one fiber fraction obtained thereby to a given ply in the paper or cardboard. In this way the fractionating is controlled so that the fiber composition in the fiber fraction obtained corresponds to a fiber composition in the input paper pulp for the given ply.

Abstract: Chemical pulp is produced by cooking comminuted cellulosic fibrous material (e.g. wood chips) in a continuous digester or batch digesters or produce brown stock, and washing the brown stock in a brown stock washer to produce chemical pulp, oxygen delignifying the chemical pulp at medium consistency, and then screening the oxygen delignified pulp to produce an accept fraction and a shive-containing reject fraction. Drawbacks inherent in the prior art are overcome by directly transporting (i.e. without refining or accessory oxygen delignification) the shive-containing rejects fraction to the main fiber line before oxygen delignification (e.g. to just before a mixer for the oxygen delignification stage, to between the brown stock washer and mixer, to a coarse screen between the digester and the brown stock washer, and/or to a washer for the coarse rejects from the coarse screen).

Abstract: A method of draining water from low-consistency water-fiber suspensions, in which the water-fiber suspension is fed to a filtering surface comprising holes. The rougher fibers are first separated from the water-fiber suspension and fed to the filtering surface to form a separate filtering layer and the water-fiber suspension is led to flow through the filtering layer formed by the rougher fibers.

Abstract: The object of the present invention is a method for making mechanical pulp, such as thermomechanical or chemi-thermomechanical stock. The mechanical pulp is used as a raw material for printing paper, and its freeness value is 30-70 ml CSF. The stock refined by the method is screened in several stages to form accept and reject stock portions. The wood raw material is refined at the first stage of refining at a superatmospheric pressure of over 400 kPa to form a stock that has a freeness value of 250-700 ml CSF.

Abstract: The object of the present invention is a method for making mechanical pulp, such as thermomechanical or chemi-thermomechanical stock. The mechanical pulp is utilised as a raw material for printing paper, and its freeness value is 30-70 ml CSF. According to the method, the refined stock is screened in several stages into accept and reject stock portions. The stock is screened at a consistency of not less than 10%.

Abstract: Xylooligosaccharide is produced from a lignocellulose pulp by enzyme-treating a lignocellulose pulp with hemicellulase, filtering the resultant reaction mixture to separate a liquid fraction from the enzyme-treated pulp, subjecting the separated liquid fraction to a permeation treatment through a separation membrane to separate a non-permeated fraction containing xylooligosaccharide-lignin complex with an increased concentration from a permeated fraction, collecting the non-permeated fraction, and separating and recovering xylooligosaccharide from the collected non-permeated fraction.

Abstract: Provided herein are compositions of matter useful in de-inking secondary fibers. A composition according to the invention includes an aqueous solution of an anionic form of a styrene-methacrylic acid copolymer. When a surfactant is used in combination with the copolymers herein described in a de-inking operation, a synergy is observed in that the combination of copolymer and surfactant combination together yield a recycled fiber product having higher brightness level and a lower effective residual ink concentration than recycled fibers produced using either the copolymer or surfactant alone in the same operation.

Abstract: Lignocellulose pulp is bleached by bleaching a pulp in aqueous alkali solution with oxygen and treating the pulp with a hemicellulase, while a liquid fraction delivered from the enzyme treatment step is separated from the hemicellulase treated reaction mixture, and subjected to a penetration treatment through a separation membrane, for example, reverse osmosis membrane, to separate a permeated fraction from a non-permeated fraction; the permeated fraction is fed to the alkali-oxygen bleaching (oxygen delignification) step and is used as a liquid medium of the bleaching system.

Abstract: Provided herein are compositions of matter useful in de-inking secondary fibers. A composition according to the invention includes an aqueous solution of an anionic form of a styrene-methacrylic acid copolymer. When a surfactant is used in combination with the copolymers herein described in a de-inking operation, a synergy is observed in that the combination of copolymer and surfactant combination together yield a recycled fiber product having higher brightness level and a lower effective residual ink concentration than recycled fibers produced using either the copolymer or surfactant alone in the same operation.

Abstract: A product and process of making an absorbent paper article such as paper products, towels, napkins and the like is disclosed. In the invention, one may supply a single furnish, or slurry, of cellulose fibers. Then, it is possible to separate or fractionate the slurry into at least two portions based upon fiber length in the slurry. Fines are employed in the process of manufacturing the products, and fines are specifically incorporated into an inner layer of the final paper products. Fines, short fibers, and/or fibrils are used in the process so they may contribute in a positive manner to the final paper product, rather than acting in a negative manner as a chemical “sponge” or waste material. This use of fines in the inner layers of the product reduces the manufacturing cost and waste produced in the process. A soft paper product with good strength characteristics results from the process.

Abstract: A device and process for aerating dispersions, particularly for flotation of pulp suspensions, in a de-inking process. The process includes at least two stages, where each stage has a separate liquid circulating system which sucks in the gas or air and mixes it with the liquid. The device has at least two flotation cells, with each of the cells having a separate injector and a separate circulation system including a pump.

Abstract: A feather molding process and the molded product produced therefrom. The inventive method comprises the steps of: (a) reducing feathers in a refiner, a pulper, or a combination thereof; (b) cleaning the feathers using a cleaning agent; (c) diluting at least a portion of the reduced feather material to form a slurry; and (d) delivering the slurry to a vacuum molding apparatus to form a molded product.

Abstract: The amount of metals that can be removed from comminuted cellulosic fibrous material (such as wood chips) in the production of chemical pulp, prior to bleaching, is enhanced by extracting metals during an early stage of digestion, and prior to the addition of a chelating agent. After the material is steamed and slurried it is impregnated with cooking liquor at a temperature of 90° C. or more, and during or after impregnation metals are removed by an extraction (e.g. in a continuous digester), which typically removes about 30% or more of the Mn. Prior to this extraction it is not necessary to introduce chelating agents, and undesirable to do so since they may compete or interfere with the natural removal of metals. After the extraction, such as during the first part of cooking, about 0.05-10 kg/dry ton of material of chelant (such as EDTA) is added, and the chelant combines with released metal ions in the slurry to produce metal complexes. The metal complexes are substantially removed before bleaching.

Abstract: A hybrid method for processing papermaking fibers to remove high density stickies typically includes utilizing a multistage array of forward cleaners coupled with a flotation cell which increases overall efficiency of the system. In a preferred embodiment, a first rejects aqueous stream from a first stage bank of centrifugal cleaners is treated in a flotation cell before being fed to a second stage bank of centrifugal cleaners. With the improved technique, the accepts from the first stage bank of centrifugal cleaners may be combined with the accepts from the second stage bank of centrifugal cleaners and fed forward to a thickening device, for example. The technique is also suitably employed for removing stickies from material which has already been screened with a fine screen.

Abstract: A feed system for a cellulose pulp treating vessel (such as a continuous digester) is not limited by the required L/W ratio of the pump feeding a wood chip slurry to a high pressure transfer device, the feed system may be kept at a low temperature to minimize flashing of liquid into steam, and a return conduit from the treatment vessel to the transfer device high pressure inlet may be eliminated. Some of the liquid is removed from the slurry just before the low pressure inlet to the transfer device, and/or just after the high pressure outlet, to reduce the L/W ratio of the slurry by at least 0.25, e.g. from 3.0:1 to 2.25:1 just before the low pressure inlet, and from, 7.0:1 to 5.0:1 substantially immediately after the high pressure outlet.

Abstract: Methods and devices are provided for treating a fluid with a high voltage electric field for decontaminating the fluid or a variety of other purposes. In a preferred embodiment for decontamination, the method includes (a) applying an electric field across a fluid having contaminants dispersed therein; and then (b) flowing the fluid through a decontamination cell to separate from the fluid at least a portion of the contaminants. An apparatus for use with this method preferably includes an electropotential cell comprising a housing containing an anode and a cathode for applying an electric field to a fluid flowing through the housing, a decontamination cell in fluid communication with the electropotential cell for separating from the fluid at least a portion of any contaminants dispersed therein, and an optional means for introducing gas bubbles into the fluid before the fluid flows to the electropotential cell.

Abstract: A process and apparatus for the preparation of improved cellulose pulps is provided, in which defibered pulp is screened for removal of shives, and fibers with low bonding ability are removed in hydrocyclones, and rejects from the hydrocyclones are treated in refiner. In the process a specific combination of characteristics for the hydrocyclones and the volumetric flow is used in order to prepare pulps which give products of improved qualities, such as higher tensile strength, tear strength, light-scattering, surface smoothness, and specially low shive content.

Abstract: A method of treating solid containing material derived from effluent or sludge from a plant for de-inking paper, the material containing calcium in the form of one or more insoluble calcium compounds, the method including the steps of treating the material with an acid to cause dissolution of the calcium thereby forming a calcium ion-containing solution in which insoluble solids are suspended, separating the solution from the insoluble solids and incinerating the separated solids. The solution containing calcium ions may be treated by adding one or more reagents to form a calcium compound precipitate, eg calcium carbonate. The particulate solids produced following the incineration step and following the precipitate formation may be employed as pigments or fillers in paper making or paper coating.

Abstract: A method for manufacture of loaded paper or paperboard products, comprising the steps of separating at least one process stream from the papermaking process, wherein the process stream includes fines and/or filler; combining the process stream with long fibers and thickening to form a residue; treating the residue to form fiber-filler complexes; and using the fiber-filler complexes in the papermaking process to form the paper.

Abstract: The present invention is generally directed to a process for recycling paper containing wet strength additives. The process generally includes the step of mechanically fiberizing the paper in order to reduce the paper into substantially discreet fibers. The paper can be fiberized in various devices, including mills and pulverizers. Once the paper has been converted into substantially discreet fibers, the fibers can then be used in forming various paper products, including wipers and tissues. Of particular advantage, it has been discovered that fibers produced according to the process of the present invention produce paper webs having high bulk, high brightness, high porosity, and high opacity.

Abstract: A hybrid system for processing papermaking fibers includes a multistage array of forward cleaners coupled with a flotation cell which increases overall efficiency of the system. In a typical embodiment, a first rejects aqueous stream from a first stage bank of centrifugal cleaners is treated in a flotation cell before being fed to a second stage bank of centrifugal cleaners.

Abstract: Recycled fiber pulp from a vortex cleaning plant (e.g. connected to the short circulation of a paper machine) effects the recovery and return of fillers in the recycled fiber pulp discharged from the vortex cleaning plant, in an efficient and economical manner. The loss of filler in the recycled fiber pulp discharged from the vortex cleaning plant is decreased by treating a concentrated fraction of the rejects from the vortex cleaning plant with a mixer/disperser for dispersing the filler in the recycled fiber pulp, and returning as much usable filler as possible back to the process.