A. Ahlstrom Corporation

Wisaforest Oy Ab

Ronkonharju

Lasse Hernesniemi

Pikka Olavi

A method of defiberizing fibrous cellulosic material bound by chemical bonds and physical force comprising treating the fibrous cellulosic material in a treatment apparatus so as to loosen the chemical bonds between the fibers but to leave the bonds caused by physical force essentiall undisburbed to generate treated fiber accumulations and removing a stream of the treated fiber accumulations from said treatment apparatus and defiberting the treated fiber accumulations by subjecting the material to shear forces in the stream, the shear forces being of sufficient strenth to substantiallyl break the physical forces keeping the fibers together and to separate the fibers. The method of which is performed by step (1) introducing the fibrous material in the form of wood chips into a digester and by chemically treating the wood chips in the digester at a pressure and cooking temperature beyond the difiberation point of the fibrous material so as to soften the wood chips and to loosen the fibers; step (2) removing a tream of the treated wood chips from the digester and step (3) by defiberizing the treated wood chips by generating shear forces in the stream, the shear forces being of sufficient strength to substantially separate the fibers and by subjecting the wood chips to the shear forces.

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Karhul, Finland

Ronkonharju