Defibrator Ab

H S Bystedt

Bo G Falk

Ake O Sandstrom

Method of producing peroxide bleached pulp from fibrous lignocellulose materials which are subjected to a defibration step in a grinding space defined between a pair of discs which rotate relative to one another within a steam pressurized grinding housing. The pulp material is fed into the central portion or 'eye' of the grinding space by a screw conveyor which rotates in a bore communicating with the grinding housing to form a steam-tight plug to prevent blow-back of pressurized steam from the grinding housing. The steam-tight plug, upon entry into the central portion of the grinding space, is broken up into fiber bundles which are accelerated radially outwards in the grinding space by the centrifugal force while being subjected to progressively increasing defibrating action. A peroxide-containing bleaching solution is introduced into the grinding space so as to react with the separated fibers of the pulp material during the defibrating action.

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Daderyd, Sweden

H S Bystedt