Water spray for smooth surface gypsum fiberboard panels
AssigneeUnited States Gypsum Company
InventorsWeixin Song, David Paul Miller
Life of this patent
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Abstract
An improved method and apparatus for imparting a smooth surface to gypsum fiber panels. The method involves imparting energy to the surface of a slurry as the slurry is dewatered just prior to rehydration. The apparatus used to impart the energy is a water spray including a source of pressurized water such as a pump, a distribution manifold and a plurality of nozzles to direct the water spray at the surface of the slurry. In operation, the water spray is directed against the surface of the slurry. The flow disrupts the slurry to a fraction of its total depth, thus dispersing clumps or flocs of commingled crystals and fibers in the depth that would give the surface of the finished panel a rough surface if they were allowed to remain.
Claims17
A method for making a smooth surfaced gypsum fiberboard panel comprising the steps of:
- 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 water spray at said pond of slurry to impart energy to the slurry pond surface;
- dewatering said pond of slurry to form a filter cake;
- pressing said filter cake to form a board and to remove additional water therefrom;
- and
- drying said board to remove any remaining free water.
A method for making a smooth surfaced gypsum fiberboard panel comprising the steps of:
- 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 calcium sulfate hemihydrate and host particles on a surface to form a pond of slurry;
- creating a wet line atop said slurry;
- directing a water spray against the pond of 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.
A method of imparting a smooth surface to a fiberboard panel comprising the steps of
- providing a slurry of material;
- depositing the material on a surface to form a slurry pond;
- directing a water spray upon the surface of the 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 panel.
Dependencies are inferred from the claim text.