Method for making smooth surfaced gypsum fiberboard panel
First Claim
1. A method of imparting a smooth surface to a fiberboard panel comprising the steps ofproviding a slurry of material including fibers;
- depositing the material on a surface to form a slurry pond;
directing a low pressure flow of air upon the surface of the slurry pond at a slight angle of incidence to disrupt the slurry below the pond surface so as to break flocs or clumps of material present in said slurry pond;
removing a majority of the water present in the slurry pond to form a filter cake; and
pressing said filter cake into a fiberboard panel.
1 Assignment
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Accused Products
Abstract
An improved method and apparatus for imparting a smooth surface to a gypsum fiber panels. The method involves imparting energy to the surface of the slurry as the slurry is dewatered just prior to rehydration. The apparatus used to impart the energy is an air lance including an air source such as a blower, a distribution manifold and a plurality of nozzles to direct the flow of air at the surface of the slurry. In operation, the air lance directs a flow of air against the surface of the slurry. The flow disrupts the slurry to a fraction of its total depth, thus dispersing clumps or flocs of crystals in the depth that would give the surface of the finished panel a rough surface if they were allowed to remain.
42 Citations
12 Claims
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1. A method of imparting a smooth surface to a fiberboard panel comprising the steps of
providing a slurry of material including fibers; -
depositing the material on a surface to form a slurry pond;
directing a low pressure flow of air upon the surface of the slurry pond at a slight angle of incidence to disrupt the slurry below the pond surface so as to break flocs or clumps of material present in said slurry pond;
removing a majority of the water present in the slurry pond to form a filter cake; and
pressing said filter cake into a fiberboard panel.- View Dependent Claims (2, 3, 4, 5)
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6. A method for making a smooth surfaced gypsum fiberboard panel comprising the steps of:
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mixing ground gypsum and host particles of a fibrous reinforcement material and sufficient liquid to make a dilute slurry consisting of at least about 70% liquid by weight;
calcining said gypsum, in the presence of said host particles, by heating said dilute slurry under pressure, to form acicular calcium sulfate hemihydrate crystals;
depositing said dilute slurry on a surface to form a pond of slurry;
directing a flow of air at said pond of slurry to impart energy to the slurry pond surface and disrupt the slurry below the pond surface so as to break up flocs of commingled acicular crystals and said reinforcement material in said pond of slurry;
dewatering said pond of slurry to form a filter cake;
pressing said filter cake to form a board and to remove additional free water therefrom; and
drying said board to remove any remaining free water. - View Dependent Claims (7, 8, 9, 10, 11)
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12. A method for making a smooth surfaced gypsum fiberboard panel comprising the steps of:
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mixing ground gypsum and host particles of a fibrous reinforcement material and sufficient liquid to make a dilute slurry consisting of at least about 70% liquid by weight;
calcining said gypsum, in the presence of said host particles, by heating under pressure and forming calcium sulfate hemihydrate;
depositing said dilute slurry on a surface to form a pond of slurry;
directing a flow of air against said pond of slurry to disrupt the slurry below the pond surface so as to break up flocs of commingled calcium sulfate hemihydrate and fibrous reinforcement material in the slurry;
removing a major portion of liquid from said pond of slurry to form a filter cake;
rehydrating said gypsum;
pressing said filter cake to form a board; and
drying said board.
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Specification