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US 5,520,779 AGranted
Process and apparatus for producing fiber-reinforced plaster plates
AssigneeBabcock BSH Aktiengesellschaft Vormals Buttner-Schilde-Haas AG
InventorJorg Bold
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Abstract
Process and apparatus for the continuous production of gypsum fiber plates in which the fiber component is dewatered and rediluted with water recovered from the gypsum-fiber suspension after it has been spread on a belt, passed over at least two suction boxes and densified on the last suction box by a densifying device engaging the filter cake layer from the top.
Claims33
A process for continuous production of gypsum-fiber plates, comprising the steps of:
- (a) providing a gypsum product which has a particle size distribution with an angle of inclination greater than 40.degree. in the RRSB grain grid and is selected from the group consisting of:
- an alpha-hemihydrate gypsum having a bulk density greater than 950 g/l,
- an aridized beta-hemihydrate gypsum unground after calcination and having a bulk density greater than 700 g/l, and
- mixtures thereof;
- (b) processing cellulose-containing reinforcement fibers in the presence of water into a fiber material, mechanically dewatering said fiber material, and rediluting the mechanically dewatered fiber material with water recovered from a dewatering of a gypsum-fiber suspension, thereby forming a fiber product;
- (c) forming a thin aqueous suspension of said gypsum product and said fiber product;
- (d) distributing said suspension over a water-permeable transport belt;
- (e) removing excess water from said suspension on said water-permeable transport belt by suction assisted by mechanical means to form a filter-cake layer on said belt in a single layer filtration, thereby recovering from said suspension on said belt water which is recycled to step (b) for rediluting the mechanically dewatered fiber material;
- (f) permitting said filter-cake layer to settle on said belt;
- and
- (g) thereafter thermally drying said filter-cake layer to produce a gypsum fiber plate.
8 more elements
An apparatus for continuous production of gypsum-fiber plates, comprising:
- a continuous mixing device constructed such as to form a thin gypsum-water suspension;
- a source of gypsum and means operatively connected to said mixing device for continuously metering gypsum into said mixing device;
- means for producing an aqueous fiber suspension and a dosage device in flow connection with said means for producing an aqueous suspension and said mixing device for continuously metering fiber suspension into said mixing device;
- a device for mechanically dewatering said suspension connected between said dosage device and said mixing device to produce a dewatered suspension;
- means connected between said device for mechanically dewatering said suspension and said mixing device for redilution of said dewatered suspension with water recovered from a gypsum-fiber suspension prior to feeding a rediluted fiber suspension to said mixing device;
- means connected with said mixing device for metering water thereto;
- a dewatering screen belt provided with means connected to said mixing device for spreading said thin gypsum-water suspension onto said screen belt;
- at least two suction devices disposed in succession below said screen belt for applying different suction pressures to said screen belt thereby dewatering said suspension to form a filter-cake layer on said belt, a last of said at least two suction devices being rigid;
- and
- a densification device above said belt over at least said last suction device for densifying said filter-cake layer, said densification device comprising at least one horizontal bar swingable in contact with said filter-cake layer and transverse to a travel direction of said belt.
7 more elements
Dependencies are inferred from the claim text.