摘要:
The invention relates to a method for bleaching mechanically defibered pulp with peroxide in alkaline conditions and for washing the bleached pulp and recovering chemicals from the spent liquor the bleaching step by concentrating and combusting the spent liquor and subsequently dissolving the ash thus formed into water. According to the invention, the alkaline conditions of the bleaching step are obtained by adding sodium aluminate to the pulp to be bleached, at least a part of the added sodium aluminate being the ash dissolved in water.
摘要:
Methods of bleaching mechanical pulp under alkaline conditions with hydrogen peroxide. The methods include introducing a source of magnesium ions and hydroxyl ions to a refiner. The wood particulates are refined into a pulp in the presence of the magnesium ions and hydroxyl ions, and optionally perhydroxyl ions to simultaneously refine and bleach the pulp in a refiner.
摘要:
Methods for reducing energy required for a pulp refining processes by treating a mechanical pulp with a hemicellulase composition are presented. The enzymatic treatment can be carried out at a temperature of from about 10° C. to about 90° C., and/or at a pH of from about 2 to about 10. Paper made from the treated pulp has improved strength over paper made from untreated pulp.
摘要:
A device treats a fiber stock suspension with at least one additive, the fiber stock suspension being used for production of at least one of paper and cardboard. The fiber stock suspension includes a suspension medium and a fiber material. The fiber material has fiber surfaces, the fiber surfaces being moistened by the suspension medium. The device includes a fluffer having an inlet for receiving at least one of the fiber stock suspension and the at least one additive. The fluffer is coupled to the inlet, the fluffer being configured for separating the fiber material and enlarging a specific surface of the fiber surfaces.
摘要:
The present invention aims firstly to provide a novel technique capable of preparing bleached pulp having high brightness from materials having low bleachability containing high levels of extractives and secondly to provide a technique capable of reducing the amount of bleaching agents used in processes for preparing bleached mechanical pulps. A first aspect of the invention relates to a pretreatment comprising impregnating wood chips having low bleachability with a chemical liquor at a pH range of 7-12 in aqueous solution and draining the chemical liquor from the impregnated chips, whereby extractives contained in the chips and consuming bleaching agents can be removed with the result that the effect of bleaching agents in the subsequent bleaching step can be improved and bleached mechanical pulp having high brightness can be prepared. A second aspect of the invention relates to a process for preparing bleached mechanical pulp comprising a sequential step of defibration by primary refiningnullbleachingnullbeating by secondary refining wherein pulp fibers are washed after defibrating wood chips having low bleachability and before bleaching the pulp fibers, whereby the amount of bleaching agents used can be reduced and bleached mechanical pulp having a Hunter brightness of 45-65% after secondary refining can be obtained.
摘要:
A low energy process for the manufacture of high yield pulp that involves the processing of chemically-treated chips or wood fiber at high stresses or intensity.
摘要:
An apparatus produces elongate multi-fiber particles of extremely small size to facilitate substantially complete penetration of high consistency pulp fibers by ozone when exposed thereto. A housing is provided having first and second ends and a substantially smooth interior housing surface. A means is provided for introducing high consistency wood pulp into the housing. A source of ozone gas bleaches the high consistency pulp within the housing. A pin rotor is rotatably mounted within the housing, and includes a plurality of pins, each pin having a pin tip. A means is provided means for limiting the build up of high consistency pulp fiber accretions on the pin tips.
摘要:
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.
摘要:
In a process for manufacturing chemo-mechanical and/or chemothermal-mechanical wood pulps, raw materials containing lignocellulose, such as wood shavings, wood chips, pre-ground wood or sawdust, are first impregnated with an aqueous alcoholic SO.sub.2 solution and then heated to a temperature between 50.degree. and 170.degree. C. for a period of 1 to 300 minutes. The wood shavings are then ground to the desired degree of fineness in a defibrinating device. The process makes it possible to achieve up to 50% reduction in grinding energy in comparison with known chemothermal-mechanical processes.