Abstract: A process for hydrolysis of water-insoluble esters in the presence of a lipase, at a pH in the range of 3-7 particularly to such a process for hydrolysis of resin in pulp.

Abstract: An improved oxygen bleaching process wherein the pulp is bleached in an aqueous organic medium wherein a polyhydric alcohol constitutes between 10 and 70% by weight of the medium to produce a pulp having a viscosity at least 2.5 cp higher than a similar pulp bleached using the same conditions in an aqueous atmosphere to the same kappa no. of 8 ml.

Abstract: A method for eliminating the formation of sulfur dioxide in a refiner bleaching process is disclosed wherein a selected amount of a carbonate is added to the refiner contents at approximately the same time that sodium dithionite is added.

Abstract: Method and apparatus for ozone bleaching a medium consistency cellulosic fiber suspension include feeding the fiber suspension and an ozone in carrier gas stream under pressure into a fluidizing mixer; intimately and uniformly mixing the fiber suspension with the ozone to achieve a bleaching reaction; passing the mixture into a first reaction vessel to permit the bleaching reaction to proceed and to consume a major part of the ozone; adding a second bleaching chemical to the mixture; separating the excess ozone and carrier gas from the mixture in a second considerably larger vessel and removing the fiber suspension from the second vessel after the effective second bleaching reaction.

Abstract: In an apparatus and method for controlling the position of a rotor in a truncated conical feeder for feeding a feed comprising a lignocellulose material and an alkaline cooking liquor to a pulping digester; the position of the rotor in the feeder is detected by a rotor position detector; and a signal indicating the detected position is input to a control device; the rotor is moved at a distance of 0.03 to 0.4 mm every 0.3 to 4 days by driving an electric motor and moving a shaft of the rotor in response to a signal, when the rotor is moved a predetermined distance, and the rotor-moving motor is stopped by a signal input from the control device.

Abstract: A method for recovering sodium from a spent cooking liquor used in a kraft pulping process employing sodium hydroxide as a cooking agent resulting in the presence of sodium and sulfur combined with various elements in the spent cooking liquor. Black liquor is converted to green liquor, and the green liquor is reacted with lime in a causticizer to produce caustic and calcium carbonate. The caustic is recovered for use as a cooking liquor and the calcium carbonate is heated in a lime kiln to provide a source of lime. Flue gases containing free lime evolved from the lime kiln are contacted with a sodium carbonate solution in a scrubber to convert lime to caustic.

Abstract: An oxygen delignification method and apparatus in which a charge of heated wood pulp is reacted with oxygen in the presence of a charge of caustic soda in a plurality of reaction stages located between mixing stages in which caustic is mixed with the wood pulp. The use of the plurality of mixing stages reduces peak pH exposure of the wood pulp that would otherwise occur if the charges of caustic and wood pulp were mixed all at once. Moreover, the caustic mixed in such manner replenishes neutralized caustic and ensures that the average pH level is increased above that in conventional oxygen delignification. The increase in average pH level favors an increase in the delignification. Filtrate from a washing stage is introduced into the mixing stages to prevent wood pulp degradation.

Abstract: A method and apparatus for treating wood pulp that includes incompletely washed brownstock, in which the brownstock is treated at a pH range of approximately 7.0 to 9.0 with a hemicellulase enzyme preparation that has a pH optimum below 6.0. Also, a method and apparatus for treating wood pulp containing incompletely washed brownstock in which the brownstock is treated at a pH range of approximately 6.0 to 9.0 with a hemicellulase enzyme preparation that has a pH optimum below 6.0 and that has a low cellulase content such that not more than about 10,000 FPU are added per ton of pulp.

Abstract: A method of bleaching chemical pulp in a sequence comprising at least four bleaching steps with final bleaching in a first and a second chlorine dioxide step. Between the chlorine dioxide steps an alkaline extraction is carried out, and washing takes place between the first chlorine dioxide step and extraction. Immediately after said washing step, NaOH is charged in an amount of 4-10 kg/ton pulp. Thereafter an oxidizing agent is admixed in an amount of at maximum 2 kg/ton pulp. After 15-120 seconds an acid is added for terminating the oxidation treatment and for lowering the pH-value, but without effecting a complete neutralization of residual alkaline.

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 delignifying raw cellulose which comprises a preliminary treatment for impregnating raw cellulose with a monopersulphuric acid solution, a successive filtration without washing with recycle of the filtered liquid to the first step, and a treatment, at low temperature and in alkaline solution at a pH higher than 9, of the previously impregnated raw cellulose in order to permit the reaction of the monopersulphuric acid with the lignin contained in the raw cellulose.

Abstract: Process for high pH metal ion chelation in pulps. Extraction and removal of detrimental metal ions and organic solvent extractives prior to delignification and bleaching is carried out on pulp, preferably kraft pulp, at a pH over 5, more preferably a pH over 6, most preferably a pH of 7-9. Aqueous pulp is first brought to a pH of about 3-6 to cause chelation and desorption of metal ions from the fiber phase of the aqueous pulp, and at the same time implementing air entrainment and evaporation. The pH is then raised, and the extractable species are removed by dewatering and washing the pulp.

Abstract: A process for chlorine-free bleaching of chemical pulp in association with the production thereof, where a suspension of the pulp preferably has a concentration exceeding 8% of cellulose-containing fiber material and where the pulp entering into a bleaching line is preferably fed continuously through at least one bleaching vessel in the bleaching line, is treated with at least one acid for adjusting the pH to a value below 7, and with a chelating agent, and is subsequently bleached in at least one stage to a brightness exceeding 75% ISO, preferably exceeding 80%, with hydrogen peroxide or the corresponding quantity of another peroxide, employed in a quantity exceeding 5 kg/BDMT, where the peroxide bleaching takes place at elevated temperature and at a pressure in the bleaching vessel which exceeds 2 bar and where the cross-sectional area of the bleaching vessel exceeds 3 m.sup.2 and the area of the metal surface exposed towards the interior of the bleaching vessel is less than 4 V m.sup.

Abstract: A multi-stage pressure diffuser is provided for treating paper pulp or similar comminuted cellulosic fibrous material. Two different subvolumes are defined within the annular screen of the pressure diffuser by a tubular baffle hung from adjacent the top of the vessel, and a transverse wall near the middle of the vessel. Wash liquid is introduced into the top stage, extracted liquid passes through the bottom of the baffle, and is removed through a liquid outlet at the top of the vessel. That removed liquid is then reintroduced into the bottom stage as wash liquid, and the extracted liquid from the bottom stage is discharged from the vessel at the bottom. The screen assembly may be blanked at the area of the transverse wall dividing the subvolumes from each other, in order to minimize the possibility of mixing of the extraction flows in the different stages.

Abstract: A method and apparatus supply ozone containing gas under superatmospheric pressure to an ozone delignification device. The speed of a water ring compressor is controlled so that it compresses as much ozone gas per unit time at desired superatmospheric pressure as the ozone delignification unit utilizes, with essentially no excess. The ozone containing gas is fed from the water ring compressor through a separator buffer tank which levels out pressure pulses and separates cooling water from compressed ozone gas prior to the gas entering the ozone delignification unit. The gas passes through a control valve controlled by a mass flowmeter which senses the amount of cellulose pulp fed to the ozone delignification unit. The speed control of the compressor may be provided by a differential pressure controller connected across the control valve.

Abstract: Paper pulp, especially recycled paper pulp which has been deinked, is bleached in a synergistic two-stage process first with sodium bisulfite and then with sodium borohydride. The borohydride is preferably added in an aqueous mixture with sodium hydroxide. A weak acid such as acetic acid may be added to the pulp to advance further the brightness gain.

Abstract: An improved process for bleaching pulps is disclosed in which the unbleached pulp is subject to flotation before bleaching and, if necessary, the circulating water is also purified of interfering compounds by flotation.

Abstract: Process for preserving the mechanical strength properties of a chemical paper pulp, comprising two treatment stages by means of a peroxidic reagent, with the first stage in an acidic medium and the second stage in an alkaline medium, according to which a treatment by means of a reducing compound is interposed between the two stages.

Abstract: Cellulosic pulps are bleached with ozone in an ozone bleaching stage in an aqueous medium containing an additive in an effective amount not exceeding 5% weight concentration of the aqueous medium. The additive is selected from a group consisting of N-alkylated ureas, N-alkylated lactams and N-alkylated amides. pH in the Z stage is operated under conventional ozone bleaching conditions, but preferably at high consistency and at low temperature, below 5.degree. C.

Abstract: Provided herewith is a process for reducing the fluorescence of pulp fibers. The process comprises contacting the pulp fibers with ozone in two or more stages, with an intermediate washing stage or bleaching stage preferably being conducted in between the ozone contacting stages. It has been discovered that splitting the total ozone charge into two or more stages provides a much more efficient and effective process for reducing fluorescence.