Abstract: A method of bleaching recycled paper containing pulp wherein said pulp is contacted with ozone in an ozone stage (Z) treatment with a brightness stabilizing step during or at the end of said ozone stage (Z), said stabilizing step consisting of contacting a small amount of hydrogen peroxide with said pulp, the amount of hydrogen peroxide contacted with said pulp being small compared to the amount of hydrogen peroxide usually in an hydrogen peroxide stage, no washing step of the pulp being provided between the ozone contacting step with said pulp and the hydrogen peroxide contacting step. The pulp is first submitted to a test procedure to determine whether the pulp is more reactive to ozone in acidic or alkaline conditions, and if necessary the pH is accordingly adjusted.

Abstract: This invention pertains to an elongated gap or extended nip press comprised of two pressing elements whose pressing areas are pressed against each other, wherein each of the press areas is formed of a band-shaped jacket element, with the jacket element moving around carriers and being supported by at least one support element, wherein a change of the length of the press gap or nip and/or of the pressure distribution or pattern in the press gap is accomplished in that the portions of the press elements that form the support surfaces and/or that the support elements of at least one of the pressing elements are displaceable in or against the direction of rotation of the respective jacket element.

Abstract: A long nip press belt for a papermaking machine has a textile substrate impregnated and coated on at least one side with a polymeric resin material. The polymeric resin material is ground and buffed after being cured to provide the belt with a smooth surface and a uniform thickness. The textile substrate includes textile components (monofilaments, continuous fine filaments or staple fibers) having non-circular cross sections with a plurality of lobes. Such cross sections provide the textile components with a greater surface area than would be provided by components of equal denier having circular cross sections. As a consequence, the mechanical interlock and chemical bond or adhesion of the polymeric resin coating to the textile substrate are strengthened. In addition, the textile components having non-circular cross-sections with a plurality of lobes reduce the permeability of the textile substrate, so that polymeric resin material applied to one side may be prevented from flowing through to the other side.

Abstract: A method of making a wood pulp is disclosed. The method includes chipping wood into wood chips and then inoculating the wood chips with an inoculum of a white rot fungi and a nutrient adjuvant selected from the group consisting of corn steep liquor, molasses and yeast extract. The wood chips are introduced into a bioreactor and incubated. The incubated wood chips are then pulped. A method of pretreating wood including chipping the wood into wood chips and inoculating the wood chips with an inoculant of the white rot fungi and a nutrient adjuvant selected from the group consisting of corn steep liquor, molasses and yeast extract is also disclosed. A method for producing paper from the treated wood chips is also disclosed. The addition of the nutrient adjuvant dramatically reduces the amount of fungal inoculant needed (by multiple orders of magnitude), to achieve similar results.

Abstract: Wear indicators (80) are formed in the seal strips (52, 54) of a suction box (44) of a suction roll assembly (15) of a papermill. The wear indicators include a space such as a bore (74) formed in the seal strip, extending through the arcuate seal surface (68, 70), and extending inwardly of the seal strip. The bores are filled with colored fill material, with red fill material (81) located deep in the bore, yellow fill material (82) placed on top of the red fill material, and green fill material (83) placed on top of the yellow fill material and reaching the seal surface of the seal strip. As the seal strip wears during the operation of the papermill, the colored fill material will be visible upon inspection of the seal strips, informing the inspector of how much farther the seal strips can be urged outwardly into engagement with the suction roll (22) in response to inflation of the inflatable biasing tubes (56, 58 and 60).

Abstract: A papermaking vacuum apparatus having a web-facing surface adapted to support a papermaking belt and comprising a head, a body and at least one vacuum slot disposed in the head and defining an aperture on the web-facing surface. The vacuum slot is in fluid communication with the web-facing surface and extends from the web-facing surface to the body which is in further fluid communication with a vacuum source. The web-facing surface comprises a textured area in the region of the web-facing surface juxtaposed with the aperture defined by the vacuum slot. This textured area creates a leakage of at least about 35 Marlatts at a pressure differential of 7 inches of Mercury. This leakage eliminates the vacuum seal between a smooth backside of the papermaking belt and the web-facing surface of the vacuum apparatus.

Abstract: The invention concerns a headbox of a paper machine wherein an inlet region is provided along the entire width of the machine for introducing the pulp suspension, a discharge region is provided for distributing the pulp suspension along the width of at least one screen, and channels are provided between the inlet region and discharge region in which turbulence is produced in the pulp suspension (turbulence region). According to the invention, the turbulence region is formed with the aid of a number of channels, the cross-section of which, perpendicularly to the plane of flow, has an elongated form and may be variable.

Abstract: A papermaking vacuum apparatus having a web-facing surface adapted to support a papermaking belt and comprising a head, a body and at least one vacuum slot disposed in the head and defining an aperture on the web-facing surface. The vacuum slot is in fluid communication with the web-facing surface and extends from the web-facing surface to the body which is in further fluid communication with a vacuum source. The vacuum apparatus comprises a plurality of sequenced vacuum sections successively spaced in the machine direction from a first vacuum section to a last vacuum section. Each vacuum section comprises at least one vacuum slot in fluid communication with the web-facing surface and defining an aperture thereon. Each vacuum section has a vacuum applied therethrough, this vacuum increasing in the machine direction between successive vacuum sections.

Abstract: A forming section for a two-fabric paper machine using at least one formation blade having a shallow cavity in its top surface. The cavity is placed and dimensioned to withdraw fluid continuously from the stock, and to propel it back through the fabric and the incipient paper web into the stock so as to cause a controlled level of localized turbulence which serves to improve formation without causing excessive drainage or fines loss. The formation blade shape, in conjunction with the forming fabric tension, is configured to provide a hydraulic seal between the fabric and the stock, so that all of the withdrawn fluid is returned to the stock.

Abstract: A blanket passes over a concave shoe which is urged against a backing roll to form a press nip. The ends of the blanket are attached to circular heads. The transition from the nip-imposed cardioid shaped to the circular shape maintained by the heads results in a region of the blanket subject to fatigue. The heads are mounted on journals for motion between inboard stops and outboard stops which are spaced apart approximately 4 inches in the cross machine direction. Positioning of the heads on the journals is controlled by four hydraulic pistons mounted between the support beam and each head. Multiple hydraulic systems are controlled to extend the life of the blanket by alternating between holding the back head fixed and letting the front head float and fixing the front head and letting the back head float.

Abstract: A two-wire former for producing a web of fibrous material, in particular a paper web, is designed as a gap-former with the following characteristics: a first and a second wires form together a twin wire; a headbox injects the pulp directly between the two wires; at least one first dewatering zone consists in the advance direction of a curved, non-rotary, interrupted surface, for example a forming shoe or several strips that form together a surface. The invention is characterized in that a convex dewatering element that starts directly at the point of impact of the jet of pulp is provided at the beginning of the first dewatering zone, seen in the advance direction, and has at least two curvature radii Ri in contact with the wires. Both curvature radii Ri are smaller than the curvature radius Ri+l that follows them in the advance direction.

Abstract: A process is disclosed for extracting pure, coarse-grain silicic acid crystals from silicic acid-containing spent lye in cellulose production, comprising adding coarse-grain silicic acid to alkalized spent lye, lowering the pH of the alkalized spent lye to about 9 such that a sediment is formed, separating the sediment formed into coarse grain and fine grain silicic acid with little lignin and lignin-containing spent lye free from silicic acid, and separating the coarse grain and fine grain silicic acid with little lignin into course grain silicic acid and lignin. At least part of the course grain silicic acid separated is fed back to the alkalinized spent lye to be desilicified.

Abstract: The invention relates to aqueous dispersions containing A. C.sub.6-22 carboxylic acids and/or resinic acids and B. C.sub.6-22 oxoalcohols alkoxylated with 2 to less than 6 mol C.sub.2-4 alkylene oxides for deinking printed wastepaper.

Abstract: A papermaking vacuum apparatus having a web-facing surface adapted to support a papermaking belt and comprising a head, a body and at least one vacuum slot disposed in the head and defining an aperture on the web-facing surface. The vacuum slot is in fluid communication with the web-facing surface and extends from the web-facing surface to the body which is in further fluid communication with a vacuum source. The vacuum apparatus has a flow management device facing said web-contacting surface of the papermaking belt and disposed such that the papermaking belt having the paper web thereupon travels between the flow management device and the web-facing surface of the head. The flow management device has an air flow resistance and controls the distribution of the air flow through the aperture on the web-facing surface such as to effectively increase in the machine direction the amount of vacuum pressure applied through the vacuum slot to the papermaking belt.

Abstract: In a twin-wire former for the production of a paper web, two wire belts (11 and 12) together form a twin-wire zone which is divided into three sections (I, II and III). In the first section (I) the two wires (11, 12) travel over a curved forming shoe (16), or a forming roll (40). They form there a wedge-shaped inlet slot (15) with which a headbox (10) is directly associated. In the second section (II), several resiliently supported strips (27) rest against the lower wire (11) and between each of said strips (27) a rigidly mounted strip (28) rests against the upper wire (12). In the third section (III) both wire belts (11, 12) pass over another curved forming shoe (23).

Abstract: A roll press including at least two rolls forming a press nip for the treatment of a web of material. A press roll includes a very flexible roll shell which is rotatable around a stationary support. The roll shell is mounted by at least one support element on the support. The support element has a concave support surface which forms a wide press nip with the backing roll. This provides a roll press which, even in the case of a backing roll which is without sag control, defines a press nip which is very substantially uniform. This is achieved by having the outer circumference of the shell of the press roll change in dimension in the axial direction from the axial center of the roll towards the ends of the roll, i.e., the outer circumference may increase or decrease. The circumference of the backing roll may or may not correspondingly change in the axial direction.

Abstract: The invention is directed to a shoe press for removing water from a traveling fiber web. The shoe press includes a planar backing surface, and a shoe assembly disposed adjacent to the backing surface. The shoe assembly and the backing surface form a press nip therebetween extending in a running direction of the traveling fiber web. Four felts extend through the press nip and carries the fiber web through the press nip. The shoe assembly includes a plurality of shoes disposed adjacent to each other in the running direction of the fiber web, with each shoe being configured to apply a selected and independent compressive force against the at least one felt and the fiber web.

Abstract: A headbox for a papermaking machine with an outlet slot that distributes pulp suspension over the, working width of the papermaking machine. For controlling operating parameters of throughput, pulp density and fiber quality of the suspension over the width of the machine, the headbox has a plurality of individual sections across the width of the machine. Each section has respective channels therethrough for passing pulp suspension. At least one connection at each section is to a controllable supply of pulp suspension where the operating parameters of that supply are controllable. Only separate operating parameter controlled streams pass through the sections of the headbox. Operating parameter control devices may deliver adjusted streams to a mixer upstream of the headbox channels. The mixer may also have individual sections across the width of the machine.

Abstract: A seam construction for a papermakers fabric wherein mating seam components are molded onto opposite ends of the fabric. The seam is assembled by matingly engaging the seam components molded onto the respective fabric ends. Preferably, the seam components are male and female and become positively locked when the seam ends are joined together.

Abstract: The Extended Nip press apparatus of this invention has an endless loop nip blanket which is clamped at each end head by a circular array of twelve clamp segments which are positioned radially by the hydraulic actuation of an axially positionable circumferential clamp ring. The blanket is separately sealed by an air tube seal which extends between the clamp ring and the interior of the blanket. Because the clamping arrangement is independent of the seal, inadvertent loss of air pressure will not cause the blanket to become unclamped.