Other

Isorel S.a.

Stig Daniel Selander

Karl N Cederquist

Bernard Marechal

Corrado D'Andrea

A method of making fiberboard using a substantially closed white water system. One or more layers of separately prepared surface pulp is applied to a layer of base pulp at the wet sheet forming stage. Lignocellulose chips in a pressure-sealed defibrating zone under generation of steam. The steam is separated at the discharge end of the defibrating zone under atmospheric pressure. The atmospheric steam is utilized to presteam the raw chips. The presteamed chips are thereafter dewatered to a moisture content coordinated to the energy demand of the defibrating treatment and the desired generation of steam prior to entering the defibrating zone. The water removed at the dewatering stage is collected for use in preparing the surface layer pulp suspension. A small portion of the base pulp to be used for the surface layer pulp is diverted to a refiner and diluted with water. The major portion of the base pulp is diluted with white water drained off and recycled from the base layer wet sheet forming stage to form a base layer suspension, which suspension is then transported by the white water to the wet sheet forming stage, where the white water and recycled to the base layer suspension stage to form a new base layer suspension. The diverted portion of the base pulp is further diluted with white water recycled from the surface layer forming stage to form a surface layer suspension. A portion of the white water recycled from the wet sheet forming stage to the base layer suspension stage is heated by a portion of the steam separated at the discharge end of the defibrating zone to drive off surplus white water to maintain a constant volume of white water.

Wet method of preparing fiberboard products in a substantially closed

Lignocellulose fiber containing chips, preheated with steam liberated from a previous chip defibration, are dewatered and then defibrated in an atmosphere of saturated steam and in the presence of backwater and suspended in backwater to form a pulp suspension whereafter wet sheets are formed from the pulp suspension, water is mechanically removed from the wet sheets and recycled as backwater to be supplied simultaneously, with dewatered chips, to the defibration step and to form a new pulp suspension and said wet sheets are dried.

Process of producing pulp, for manufacture of fiberboard, in a closed

An improved method for the manufacture of wood fiberboard according to the wet system with a closed white water system includes the steps of drying the incoming lignocellulose containing material, prior to the dilution step, to a dryness, or solid consistency, which is higher than the dryness of the wet lap or sheet before final drying to produce the fiberboard product. Formaldehyde is added to the resulting white water which is homogenized to atomize occurring precipitations through efficient agitation and dispersion prior to being recirculated for use for diluting the incoming fiber material. Thus, there is obtained an efficient closed white water system which results in a reduction of environmentally harmful discharge of polluted water as well as the production of fiberboard with enhanced appearance.

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Stockholm, Sweden

Stig Daniel Selander