Abstract: A process for bleaching a chemical paper pulp, including, in the order recited, subjecting the chemical paper pulp to treatment with oxygen in a preliminary delignification stage which does not employ chlorine in an acidic medium or a combination of chlorine and chlorine dioxide in an acidic medium; subjecting the chemical paper pulp to treatment with peroxymonosulphuric acid in a peroxymonosulphuric acid stage carried out at a temperature ranging between 75.degree. and 100.degree. C. for a period ranging between 70 and 150 minutes and at a pulp consistency of ranging between 12 and 25% of dry matter; and subjecting the chemical paper pulp to treatment with alkaline hydrogen peroxide in an alkaline hydrogen peroxide stage.

Abstract: A process for treating a substrate, e.g., lignocellulosic pulp or cellulosic pulps, with a mixed peracid solution comprising percarboxylic acid and Caro's acid which results in a higher conversion rate of the active oxygen in the hydrogen peroxide in order to provide an inexpensive and effective delignification and/or bleaching solution and the process for making the mixed peracid solution.

Abstract: A process for using ejectors to combine high pressure steam and low pressure oxygen to produce a steam and oxygen enriched gas single phase gas mixture for introduction into various pulp treatments using oxygen with the benefit of low cost compression, low capital requirements and superior oxygen mixing.

Abstract: A method and installation for bleaching a lignocellulosic pulp with ozone, while recovering an oxygen-rich gas which may be recycled or re-used. Bleaching of the pulp with ozone is preferably carried out under conditions in which ingress of air is prevented. In a multi-step bleaching process, an oxygen-rich vent gas typically containing at least 90%, by weight, of oxygen may be recovered from a second contactor for potential use in different oxygen-consuming operations in a pulp mill.

Abstract: A method and apparatus for cooling wood pulp, coming from a high temperature bleaching stage at a consistency of approximately 10%, prior to introducing the wood pulp to a low temperature bleaching stage, including the steps of exposing the pulp to a thickening press in order to extract sufficient liquor from the pulp to increase the consistency to more than 25%; fluffing the pulp and depositing it on a moving bed cooler having a provision for blowing air through the pulp; and blowing cooling air through the pulp by using an air pump device with appropriate ducting. By first thickening the pulp, the mass of pulp to be cooled is significantly reduced and energy savings proportionate to the mass reduction are realized.

Abstract: A bleached pulp having a high viscosity for a given permanganate number is formed by pretreating never dried pulp with an organic solvent medium to produce a treated pulp composed of said never dried pulp in the medium and then bleaching that treated pulp using ozone at a pH of 1.5-5 to provide a bleached pulp while reducing the viscosity loss during the ozone bleaching step significantly compared to that what would occur if the medium used in the ozone bleaching were water.

Abstract: An apparatus and process for the solvent pulping and washing of pulp using vessels purged of oxygen free gas when the process is arrested or terminated. The washing is accomplished by first continuously passing the pulp to a pressure diffuser, then to a first multi-stage drum displacer washer, and then to a second multi-stage drum displacer. In the pressure diffuser the lignin is washed out of the pulp, utilizing as wash liquid a mixture of solvent and water having a solvent concentration equal to or higher than that required by the extraction process within the digester, and at a pressure at least about 350 psi. The pressure in the second and third stages is lower, and water is the wash liquid in the third stage. Alcohol can be recovered from the spent wash liquid of the first wash stage, so that all but about ten gallons or less of alcohol per ton of pulp is recovered.

Abstract: A process for delignification and bleaching of chemically digested lignocellulose-containing pulp, where the pulp is treated with a complexing agent at a pH between 3.1 and 9.0, whereupon the pulp is bleached with ozone. The initial treatment with a complexing agent removes the ions of certain metals detrimental to the subsequent ozone bleaching, while retaining in the pulp the desirable ions, primarily of alkaline earth metals. Thereby, the selectivity in the delignification is increased and the strength of the pulp maintained. The pulp can be bleached with peroxide before the ozone step and/or after the treatment according to the invention, to obtain the desired final brightness and completely avoid formation and discharge of chlorinated organic compounds.

Abstract: Process for bleaching a chemical paper pulp by means of a sequence of treatment stages involving at least one stage with an enzyme and at least one stage with a peroxyacid.

Abstract: Methods for discharging spent cooking liquors from a batch digester containing cooked lignocellulose-containing material in spent cooking liquor are disclosed, including supplying a first portion of washing liquid to the digester to displace a first portion of the spent cooking liquor at a temperature and dry solids content which substantially corresponds to the temperature and dry solids content of the spent cooking liquor at the end of the batch digestion, supplying a second portion of washing liquid to the digester to displace a second portion of the spent cooking liquor having a temperature and dry solids content substantially lower than that of the spent cooking liquor in the digester, and maintaining the first and second portions of spent cooking liquor separate from each other. Methods of producing kraft pulp in batch digesting processes using this method are also disclosed.

Abstract: A method and apparatus facilitate removal of metals from acidic liquids containing dissolved metals (such as pulp mill bleach plant washer filtrate) by oxidizing the liquid with ozone, hydrogen peroxide, oxygen, and/or air to increase the valence of the metals (like Mn and Fe) so that they become easier to precipitate. Oxidation may be practiced using any suitable reactor, such as a gas-contact reactor, or a plunger type reactor where the oxidizing agent is primarily gaseous, or a static mixer or stirred tank where the oxidizing agent is primarily liquid. After oxidation the pH of the liquid is adjusted (e.g. to over 6, preferably about 8-11) to precipitate the metals. The precipitated metals are then removed by filtration, sedimentation or flotation, and the metals-depleted liquid used elsewhere in the pulp mill.

Abstract: Resonant tubes of a pulse combustor are immersed in a bed of solid particles in a reaction zone to provide indirect heat from the pulsating combustion gases to the solid particles of the bed. The bed is maintained in an agitated state by a gas or vapor flowing through the bed. Reactant materials are introduced into the agitated bed and undergo reaction at enhanced rates resulting from heat transfer coefficients at least about twice as high as those of steady flow combustors and an intense acoustic pressure level propagated from the pulsating combustor into the reaction zone. The apparatus is useful, for example, to steam reform heavy hydrocarbons and to gasify carbonaceous material, including biomass and black liquor to produce combustible gas at relatively low temperatures, with steam being utilized as the bed fluidizing medium. Black liquor gasification, utilizing sodium carbonate as bed solids, results in liquor energy and chemical content recovery without smelt production.

Abstract: A method for bleaching a paper web with peroxide and to a paper surface treatment mixture intended for such a method. According to the invention, peroxide is introduced onto a moving paper web as part of the said mixture, which in addition to the peroxide contains another active component, such as a bonding agent or a surface coating, to be introduced onto the web. The bonding agent may be made up of starch and a surface coating pigment, such as calcium carbonate, kaolin or talc. Peroxide is added to these so that its amount on each side of the web to be bleached will be approx. 0.08-1.0 g/m.sup.2.

Abstract: A mill for the processing and production of wood pulp is contained substantially entirely within a single, integral structure that defines a unitarily-covered space substantially bounding and enclosing the mill. The mill includes a main control room or station for overall monitoring and control of pulp processing operations in the mill, the main control station being disposed substantially centrally within the covered space, and a plurality of processing stations at which various pulp processing operations take place in a generally sequential manner or order.

Abstract: A guide vane is provided in a pin fluffer to assist in pulp mat retention during fluffing by providing a cyclic lift component to the mat as it passes over the vane thereby also further increasing retention time obtained in the fluffer.

Abstract: A method for the control of pitch in an aqueous system used in pulp or paper making is disclosed which comprises adding to the system, or to the pulp making or paper making machinery, a water soluble polymer derived from (a) an epihalohydrin, a diepoxide or a precursor of an epihalohydrin or diepoxide, (b) an alkyl amine having a functionality with respect to an epihalohydrin of 2 and (c) an amine which has a functionality with respect to an epihalohydrin greater than 2 and which does not possess any carbonyl groups.

Abstract: An apparatus for controlling the degree of fiber variations in paper sheet has a formation meter for receiving an image of transmitted light on one side of an area of paper from a light source located on the other side of the area of paper, an image processing computing element for introducing the image from said formation meter for image processing and a fuzzy control unit for calculating and outputting optimum J/W ratio, optimum foil angle, and optimum deflector pushing degree and angle on the basis of results of image processing from said image processing computing element.

Abstract: A process of delignifying and bleaching a chemical wood pulp with hydrogen peroxide and dicyandiamide as an activator provides a higher degree of delignification and brightness of the pulp and overcomes problems of fiber degradation. The process comprises adding hydrogen peroxide and dicyandiamide as a bleaching activator to a chemical wood pulp slurry under alkaline conditions.

Abstract: Chlorine dioxide is used to stabilize hydrogen peroxide in bleach liquor at alkaline pH. This is thought to be aided by the destruction of enzymes (especially catalase) produced by bacteria. The method is useful for the reprocessing of pulps, especially when a de-inking stage is involved.

Abstract: A process for treating lignocellulose pulp using a preparation containing at least one enzyme that produces a solubilizing action and, potentially, a hemicellulolytic action on lignin. The enzymes are derived from the bacterium Streptomyces viridosporus. This enzymatic treatment may be used for the separation of lignin from lignocellulose pulp in a procedure, for example, that complements a bleaching treatment.