Abstract: The invention relates to a method of bleaching and/or delignifying cellulose, in which (a) a sodium hydroxide solution and a peroxydisulphate solution are first of all produced by electrolysis of a sulphate, (b) the peroxydisulphate solution is converted by hydrolysis into a Caro's acid/caroate solution, (c) said Caro's acid/caroate solution is left to cool and (d) used immediately as a bleaching solution for bleaching and/or delignifying cellulose, the Caro's acid/caroate solution becoming neutralised upon introduction into the bleaching solution.

Abstract: A method and apparatus for heating cellulose pulp with steam are provided. Low-pressure (e.g. 3-5 bar (abs.)) steam is supplied into the pulp flowing as a plug flow in such a way that in the flow direction of the pulp, before supplying the low-pressure steam, the pulp is pressurized so that the pulp pressure at the point of the steam introduction is lower than the pressure of the available steam. After the steam is introduced the pulp is mixed with a pressure-raising mixer (such as a fluidizing centrifugal pump) to divide the steam evenly into the pulp and/or to equalize the temperature of the pulp.

Abstract: The production of chemical (e.g., kraft) cellulose pulp much more suited to totally chlorine free or elemental chlorine free bleaching is produced by reducing the bleaching chemical consumability of the produced pulp. The effective alkalinity of the pulp during at least the majority of the cooking stage is maintained at about 15 g/l or above (e.g., about 18-25 g/l), expressed as sodium hydroxide, so as to reduce the charged acid groups (including hexeneuronic acids) by at least 30% (e.g., at least about 50%) compared with pulp cooked at conventional alkalinity. Instead—or in addition to—the cellulosic material which produces the pulp may be heated to a temperature (at least about 100° C., preferably at least about 130° C.

Abstract: A system and method for rapidly determining the pulp kappa number through direct measurement of the potassium permanganate concentration in a pulp-permanganate solution using spectrophotometry. Specifically, the present invention uses strong acidification to carry out the pulp-permanganate oxidation reaction in the pulp-permanganate solution to prevent the precipitation of manganese dioxide (MnO2). Consequently, spectral interference from the precipitated MnO2 is eliminated and the oxidation reaction becomes dominant. The spectral intensity of the oxidation reaction is then analyzed to determine the pulp kappa number.

Abstract: An apparatus for continuously loading fibers in a fiber suspension with a chemical compound includes a deflocculating vessel having an interior chamber, a fluid inlet connected with the interior chamber, a fluid outlet connected with the interior chamber, and a high shear imparting device disposed within the interior chamber for imparting high shear forces to and thereby deflocculating the fiber suspension. A mixing container has an interior compartment, a fluid inlet connected with both the interior compartment and the fluid outlet of the deflocculating vessel, a fluid outlet connected with the interior compartment, and a low shear imparting device within the interior compartment for imparting low shear forces to the fiber suspension. A gas supply is connected with the interior chamber of the deflocculating vessel and/or the interior compartment of the mixing container. The gas supply is configured for supplying a gas to and pressurizing each of the deflocculating vessel and the mixing container.

Abstract: A method for continuous cooking of lignocellulosic fiber material, comprising the steps of sequentially (a) in a first stage, impregnating the fiber material in an impregnation liquid comprising alkali metal hydroxide, and thereafter withdrawing (14, 514) a spent impregnation liquid; (b) in a second stage, cooking the fiber material in a cooking liquor comprising alkali metal hydroxide; and (c) in a third stage, adding (A), to said fiber material, a liquid which is rich in hemicellulose, said liquid preferably comprising at least a part (14a, 514a) of said withdrawn spent impregnation liquid. In a fourth stage (d), the fiber material is cooked in a cooking liquor comprising the liquid added in the third stage, whereby the fiber material is subjected to a retention time of at least 1 hour in said fourth stage.

Abstract: Sanitary paper with improved softness (lower stiffness) can be obtained without significant loss of paper strength by using a papermaking pulp which is treated with a certain type of cellulase component. The cellulase component in question is characterized by not containing a cellulose-binding domain (CBD), and is more effective for making softer sanitary paper than a conventional cellulase preparation which contains a mixture of various cellulase components with and without a CBD.

Abstract: A method for producing pulp, comprising digesting lignocellulosic wood, containing one or more xylan derivatives selected from the group consisting of xylan bound with lignin, xylan bound with hexenuronic acid, and mixtures thereof, with an aqueous alkaline pulping solution containing sulfide and having an initial free hydroxyl ion concentration of at least 1 mole per liter, under conditions whereunder xylan is dissociated from said one or more xylan derivatives and the pH of the solution remains above 12.5; and then while the pH of said solution is above 12.5, adding a sufficient amount of an acidic agent to said pulping solution to precipitate dissociated xylan from said pulping solution while minimizing precipitation of lignin from said pulping solution. Carbon dioxide is a preferred acidic agent.

Abstract: Processes are disclosed for bleaching pulp with ozone in an environmentally friendly bleaching plant. The processes include removing a first filtrate from the pulp, bleaching the treated pulp with ozone, washing the bleached pulp with a washing liquid to provide a washed bleached pulp and a second filtrate including oxalic acid, recycling the second filtrate to the pulp prior to the bleaching step, and transferring the first filtrate to the bleached pulp.

Abstract: Methods for oxygen delignification of a pulp are disclosed, including initially delignifying the pulp at a delignification temperature of less than 90° C., adding oxygen to the pulp so that the oxygen is present during the initial delignification step, and further delignifying the pulp at a delignification temperature of greater than 90° C., the difference between the two delignification temperatures being less than about 20° C., and the pressure being greater in the initial delignification step. The method also includes adding alkali solely to the initial delignification step in order to obtain high alkalinity therein.

Abstract: An on-line pulp digester control system. More particularly, this invention pertains to a control system which employs real time measurements from ion mobility spectrometry to automatically rapidly and continuously determine the physical and chemical characteristics of wood chip feedstock being fed into a pulp digester and thereby maximize process efficiencies, minimize chemical and energy consumption and improve product uniformity.

Abstract: A process for bleaching chemical pulp for paper manufacturing comprising delignifying and bleaching chemical pulp which has been treated by cooking by simultaneous use of chlorine dioxide, a peroxide, and at least one reaction catalyst selected from the group consisting of oxoacids of elements of Groups IV, V and VI and salts of these acids. Formation of organic chlorine compounds as by-products is suppressed by decreasing the amount of chlorine dioxide used in the ECF bleaching process in the first stage, and thus environmental toxicity in the waste water discharged from the bleaching process is decreased. Chemical pulp having a high degree of brightness is economically produced because increase in the production capacity is not required at all or suppressed to the minimum, and the investment cost is reduced to the minimum when the bleaching with chlorine in the first stage is converted into the bleaching with chlorine dioxide which is an ECF bleaching process.

Abstract: A method of stabilizing hydrogen peroxide in an aqueous solution, such as a circulating water slurry, comprising a peroxide, such as hydrogen peroxide. The aqueous solution may include organic matter. The method comprises adding an aldehyde donor, such as a methylolhydantoin, to the solution (or slurry). The inventors have discovered that aldehyde donors significantly reduce the decomposition of hydrogen peroxide by catalase and other peroxide decomposing enzymes, which are often present in recycled paper. As a result, less hydrogen peroxide needs to be added to a solution to effectively bleach organic matter in the solution. Furthermore, aldehyde donors are safe to handle and cost effective. Another embodiment is a method of bleaching recycled papers in a circulating water slurry comprising organic matter. The method comprises adding hydrogen peroxide and an aldehyde donor to the slurry.

Abstract: A process for final bleaching cellulose-containing pulp which has been subjected to previous bleaching with a peroxide compound. The process involves the sequential steps of exposing the pulp to an amount of a reducing agent in order to eliminate residual peroxide compound from the pulp and then final bleaching the pulp by exposing the pulp to an amount of formamidine sulfinic acid.

Abstract: A multi-function process is described for the separation of cellulose fibers from the other constituents of lignocellulosic biomass such as found in trees, grasses, agricultural waste, and waste paper with application in the preparation of feedstocks for use in the manufacture of paper, plastics, ethanol, and other chemicals. This process minimizes waste disposal problems since it uses only steam, water, and oxygen at elevated temperature in the range of 180° C. to 240° C. for 1 to 10 minutes plus a small amount of chemical reagents to maintain pH in the range 8 to 13. An energy recuperation function is important to the economic viability of the process.

Abstract: A method of treating wood-fiber pump, particularly wood-fiber pulp that contains recycled paper, comprises delivering the pulp to and advancing the pulp in a heating zone while delivering steam to the heating zone. The pulp is finely-divided in a disperser and the finely-divided pulp delivered to a screw press without separate departure of steam, so as to compact the pulp in the end of the screw press and therewith form a plug seal. At the same time, one or more bleaching chemicals is or are supplied during one or more treatment stages, and the temperature of the pulp is regulated to obtain an optimal bleaching process or optimal bleaching processes. The temperature of the pulp can be raised or lowered by supplying steam or water thereto respectively. The invention also relates to a plant for carrying out the method.

Abstract: Wood fiber morphology can be permanently altered by introducing a substantial kink, twist, curl, crimp or other curvilinear deformation into a wood fiber. Wood fibers are first Fiberized using mechanical treatment processes and then are subjected to super atmospheric temperature/pressure steam explosion processing. The fiber morphology becomes a permanent characteristic of the fiber which is not relaxed in time, by contact with other treatments or through use.

Abstract: A process for delignification and bleaching of chemically digested lignocellulose-containing pulp. In a first embodiment, the pulp is acid treated at a pH of between about 1 and about 6, whereupon a water-soluble compound containing an alkaline earth metal is added at a pH of between about 1 and about 7 before the pulp is treated with a chlorine-free bleaching agent. In a second embodiment, the acid and alkaline earth metal treatments are carried out in a single step. The chlorine-free bleaching agent includes peroxide compounds, ozone, oxygen and sodium dithionite in an optional sequence or mixture. After the treatment according to the invention, the pulp may be finally bleached to the desired brightness, suitably with a chlorine-free bleaching agent, such as ozone, to completely avoid formation and discharge of AOX.

Abstract: A system and a process for the oxygen delignification of pulp consisting of lignocellulose-containing material whose mean concentration is 8-18% pulp consistency, in at least two stages. The invention is characterized in that the oxygen delignification takes place in a first stage with a short dwell time of approx. 3-6 minutes, at a low temperature of approx. 85° C. and under a low pressure of approx. 0-4 bar, followed by a concluding stage with a longer dwell time of approx. 50-90 minutes, at a higher temperature of approx. 100° C. and under a higher pressure of approx. 8-10 bar. This makes it possible, in an industrial process, to exploit the kinetics of the oxygen delignification in an optimal manner for the purpose of obtaining a selective oxygen delignification at low installation cost and at low operating cost.

Abstract: Process for the production of cellulose paper pulps from vegetable masses, comprising the steps of mixing and conditioning a vegetative mass suitable to form a culture medium with an inoculum constituted of edible ligninolythic mushrooms, such as Lentinus edodes, Pleurotis Peryngii, Psajor-caju, and the like; extracting the so-obtained enzyme and adding it to the vegetative material for the production of paper pulp, mainly constituted of cultivated annual plants such as kenaf, hemp, flax, cotton and various stems and/or agricultural-industrial residues, such as cereal straws, maize stalks, and the like; conditioning and causing the mass to react; and lastly washing the mass after the biological attack, obtaining in this way a cellulose pulp to be submitted to possible mild final cooking and bleaching treatment. Apparatus for the realiztion of the process, and cellulose pulps obtained by biodelignification of cultivated annual plants and/or agricultural-industrial residues.