Gypsum fiberboard panel as well as method and apparatus for the production of a gypsum fiberboard panel

Abstract

A method for production of a gypsum fiberboard panel, has the following method steps: production of a mixture of calcined gypsum and fibers; application of the mixture to a gas-permeable and/or air-permeable and/or liquid-permeable conveyor that continuously moves in an advancing direction, at an advancing speed; pre-compaction of the mixture; wetting of the mixture with setting water; post-compaction of the mixture; pressing the mixture to form a gypsum fiberboard panel strand; cutting the gypsum fiberboard panel strand into individual gypsum fiberboard panels; drying the gypsum fiberboard panels; and if necessary, finishing and/or coating the dried gypsum fiberboard panels; wherein for pre-compaction, the mixture is sprayed with a water mist and has a partial vacuum applied to it. Furthermore, an apparatus produces a gypsum fiberboard panel, in particular by carrying out the method, and a gypsum fiberboard panel is produced using the method and/or using the apparatus.

Claims

1. A method for production of a gypsum fiberboard panel, the method comprising: producing a mixture of calcined gypsum and fibers; applying the mixture to a gas-permeable and/or air-permeable and/or liquid-permeable conveying means that continuously moves in an advancing direction, at an advancing speed; pre-compacting the mixture, wherein during pre-compaction, the mixture is pre-wetted by spraying a first surface of the mixture with a water mist in the form of an aerosol having an average droplet size of 0.1 to 60 μm while a partial vacuum is applied to a second surface of the mixture opposite the first surface to draw the water mist into the mixture; after the mixture is pre-wetted, wetting the pre-wetted mixture with setting water; post-compacting the mixture; pressing the mixture to form a gypsum fiberboard panel strand; cutting the gypsum fiberboard panel strand into individual gypsum fiberboard panels; drying the gypsum fiberboard panels; and if necessary, finishing and/or coating the dried gypsum fiberboard panels.

2. The method according to claim 1, wherein the mixture is produced with the following composition: TABLE-US-00002 Raw material Proportion [weight-%] Gypsum 75 to 85 Fibers  5 to 20 Aggregate  0 to 10 Additive  0 to 2.

3. The method according to claim 1, wherein the advancing speed of the conveying means is set to 50 to 500 mm/s.

4. The method according to claim 1, wherein a water/solid value w/s of 0.05 to 0.25 is produced in the mixture for pre-compaction with the water mist.

5. The method according to claim 1, wherein for pre-compaction, the mixture is sprayed with a water amount of 1 to 10 liters per hour.

6. The method according to claim 1, wherein 1 to 35 atomizer nozzles are used to generate the water mist, which are each operated at an air pressure of 2 to 4 bar and a liquid pressure of 1 to 3 bar and a jet angle of 40 to 80°.

7. The method according to claim 1, wherein a partial vacuum of 5 to 20 mbar is applied to the mixture for pre-compaction.

8. The method according to claim 1, wherein the partial vacuum is applied on the conveying means underside for pre-compaction, so that the partial vacuum acts on the mixture through the conveying means.

9. The method according to claim 1, wherein the setting water for wetting is applied to a first surface of the mixture and the partial vacuum is subsequently applied on a second surface of the mixture opposite the first surface for post-compaction.

10. The method according to claim 1, wherein for wetting with the setting water, a water/solid value w/s of 0.4 to 0.6 is produced in the mixture.

11. The method according to claim 1, wherein the mixture has a partial vacuum applied to it for post-compaction, wherein a partial vacuum of 10 to 25 mbar is generated, wherein the amount of air drawn off to generate the partial vacuum is increased section by section in the advancing direction.

12. The method according to claim 1, wherein a pressure of 100 to 350 bar is applied for pressing the mixture.

13. The method according to claim 1, wherein gypsum fiberboard panels having a thickness of 6 to 50 mm are produced.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other objects and features of the invention will become apparent from the following detailed description considered in connection with the accompanying drawings. It is to be understood, however, that the drawings are designed as an illustration only and not as a definition of the limits of the invention.

(2) In the drawings,

(3) FIG. 1 shows an apparatus according to the invention; and

(4) FIG. 2 shows a pre-compaction device used in the method according to the invention and in the apparatus according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(5) In the individual figures, the same parts are always provided with the same reference symbols. Furthermore, in connection with the figure description, it is explicitly emphasized that the invention is not restricted to the exemplary embodiments shown and thereby not to all or multiple characteristics of the combinations of characteristics that are described. Instead, each individual partial characteristic of the exemplary embodiment or of each exemplary embodiment can also have inventive significance even dissociated from all the other partial characteristics described in connection with it, by itself and also in combination with any desired characteristics of another exemplary embodiment, and also independent of the claims and their antecedents.

(6) An apparatus 1 according to the invention, for production of a gypsum fiberboard panel 2, is shown in FIG. 1. The apparatus 1 has a conveying device 3 having a conveying means 3a that can be driven in an advancing direction A, for conveying a raw material mixture 13 that can be poured. The apparatus 1 furthermore comprises a raw material application device 4, a pre-compaction device 5, a wetting device 6, a post-compaction device 7, a pressing device 8, a cutting device 9, a drying device 10, a finishing device 11, and a coating device 12, which are disposed one behind the other in the advancing direction A of the conveying means and through which the latter can pass.

(7) The conveying device 3 is configured as a driven conveyor belt and, in particular, has a screen belt 3a as the conveying means (FIG. 2). Furthermore, the conveying device 3 has known drive means, for example electric motors, with which the screen belt 3a can be driven in the advancing direction A at an advancing speed V.sub.A. An advancing speed V.sub.A of 50 to 500 mm/s, for example, can be set depending upon the thickness of the raw material mixture 13. The screen belt 3a has a contact surface to which the mixture 13 can be applied. The screen belt 3a is gas-permeable and water-permeable, i.e. is formed from a gas-permeable and water-permeable material, in particular air-permeable, so that gases, in particular the ambient air, can flow into the screen belt 3a from one side and flow out again on the other side. This will be discussed in greater detail below.

(8) The raw material application device 4 has a mixing device 4a and a feed device 4b. The raw material application device 4 is a spreading machine, for example.

(9) The mixing device 4a is connected with a supply container 17 for gypsum 14, a supply container 18 for paper fibers 15, and further supply containers 19 for aggregates, additives, and admixtures 16. The mixing device 4a can be filled from the containers 17, 18, 19 with an amount of gypsum 14, fibers 15, and other materials 16 determined for production of the mixture 13. The mixing device 4a thereby serves for mixing and producing the mixture 13.

(10) It is advantageous if a paper processing device 20 is assigned to the fiber container 15 of the mixing device 4a, by means of which former device scrap paper 21, which can be passed to the processing device 20, can be recycled to produce the paper fibers 15. The paper processing device 20 involves hammer mills and fiber mills.

(11) The feed device 4b is connected with the mixing device 4a. The feed device 4b is configured in such a manner that the mixture 13 that can be produced by the mixing device 4a can be spread onto the screen belt 3a with a predeterminable mixture height or mixture thickness.

(12) The pre-compaction device 5, which is shown in greater detail in FIG. 2, has means for spraying 22 the mixture 13 with a water mist 23 as well as means 24 for applying a partial vacuum to the mixture 13, preferably at the same time.

(13) The means for spraying 22 comprise a water supply container 25, a spray chamber 26 having at least one mist nozzle 27 for producing the water mist 23, as well as a water feed line 28, by means of which the water can be fed to the mist nozzle 27 from the water supply container 25.

(14) The spray chamber 26 has a preferably block-shaped housing 29, which is disposed above the screen belt 3a. The housing 29 is preferably disposed so as to surround or enclose the screen belt 3a, so that the screen belt can move through a housing interior or spray chamber interior. In particular, the housing 29 has two opposite side walls 29a, which extend parallel to the advancing direction A in a longitudinal direction B, as well as two end walls 29b, which run perpendicular to these and extend in a width direction C, as well as a ceiling wall 29c that extends perpendicular to the walls 29a, 29b and extends in a height direction D. The end walls 29b have a passage opening 30, in each instance, through which the screen belt 3a, with the mixture 13 lying on it, can be conveyed into the housing 29 or into the spray chamber 26 on one housing side, and conveyed out again on the opposite housing side. The passage opening 30 has a width in the width expanse of the screen belt 3a or in the width direction C, and, perpendicular to this, a height in the height direction D. The width is dimensioned in such a manner that the screen belt 3a can be moved through the passage opening 30 with the smallest possible distance, preferably of 1 to 5 mm, from the respective side wall 29a. The height of the passage opening 30 corresponds to the distance of a lower edge of the side wall 29b from the screen belt 3a or from the mixture 13. Preferably, the height of the passage opening 30 can be adapted to the height of the mixture 13 determined to be spread onto the screen belt 3a. In particular, the end wall 29b can be moved up and down, in driven manner, in the height direction D, so that the height of the passage opening 30 can be increased or reduced.

(15) The mist nozzles 27 are disposed within the housing 29, preferably on the ceiling wall 29c. Preferably, 1 to 35, preferentially 14 to 28 mist nozzles 27 are provided. It is practical if the mist nozzles 27 are disposed in the spray chamber 26 distributed at a regular distance from one another, and directed in the direction of the screen belt 3a, so that a first free top side 13a of the mixture 13, facing away from the conveying means, can be uniformly sprayed with the water mist 23. Preferably, the mist nozzles 27 are configured, in each instance, for spraying an aerosol consisting of gas, for example nitrogen, or air and of water particles, having a droplet path configured in cone-like manner, i.e. an aerosol cone 31. For example, the aerosol cone 31 can be generated with an air pressure of 2 to 4 bar, preferably 3 bar, and a liquid pressure of 1 to 3 bar, preferably 2 bar, and a jet angle of 40 to 80°, preferably 60°, wherein the water particles have an average droplet size, in particular, of 0.1 to 60 μm, preferably 15 μm. The mist nozzles 27 are, for example, pneumatic atomizer nozzles, type Lechler 136.231.35 A2.

(16) The water mist 23 that can be sprayed onto the mixture 13 by the means 22 for spraying is thereby preferably formed of multiple aerosol cones 31. Preferably, the mixture 13 can be continuously sprayed with the water mist 23.

(17) The means 24 for applying a partial vacuum to the mixture 13 have a partial vacuum generation device (not shown), by means of which a partial vacuum can be generated and can be applied to an underside 13b that lies opposite the free top side 13a and faces the conveying means. Preferably, the means 24 are structured in such a manner so as to apply the partial vacuum on an underside of the screen belt 3a, so that the partial vacuum can be applied to the mixture 13 through the screen belt 3a. Preferably, a partial vacuum of 5 to 20 mbar, preferably of 10 to 15 mbar, preferentially of 10 mbar can be applied to the mixture 13. By means of applying the partial vacuum, the water mist 23 can be drawn into the mixture 13. Preferably, the means 24 are a vacuum tray.

(18) The wetting device 6 has means 32 for watering the mixture 13 with the setting water required for setting of the gypsum/fiber mixture, as well as a water supply container 33 connected with the water supplying means 32, for feed of the setting water. The water supplying means 32 is preferably configured as a water curtain.

(19) The post-compaction device 7 preferably has means for generating a partial vacuum, by means of which the setting water can be drawn into the mixture, post-compacting the mixture 13. Preferably, the means for generating a partial vacuum are formed analogous to the means 24 of the pre-compaction device 5 and have a partial vacuum generation device for applying a partial vacuum to the underside 13b of the mixture 13. Preferably, the partial vacuum can also be applied to the underside of the screen belt 3a, so that the partial vacuum can be applied to the mixture 13 through the screen belt 3a. Preferably, a partial vacuum of 10 to 25 mbar, preferably of 15 to 20 mbar, preferentially of 20 mbar can be applied to the mixture 13, using the post-compaction device 7. In particular, the partial vacuum can be applied in such a manner that the amount of air drawn off to generate the partial vacuum can be increased section by section along the conveyor belt underside, viewed in the advancing direction A. Preferably, the post-compaction device comprises a vacuum tray.

(20) The pressing device 8 has means for pressing or compaction of the mixture 13 to produce a gypsum fiberboard panel strand, in particular a continuous one, having a thickness corresponding to the gypsum fiberboard panel 2 to be produced. The pressing device 8 is preferably a cycle press or ContiRoll press.

(21) The cutting device 9 has means for disaggregation, for example cutting blades or water-jet cutters, of the gypsum fiberboard panel strand along the width direction C, to produce individual gypsum fiberboard panels 2. The cutting device 9 thereby serves for separating the gypsum fiberboard panel strand to produce the gypsum fiberboard panels 2.

(22) The drying device 10 has means for drying the gypsum fiberboard panels 2. This is preferably a multi-level dryer.

(23) The finishing device 11 has means for finishing the gypsum fiberboard panels 2, such as, for example, a grinding device, an edge profiling device or the like.

(24) The coating device 12 has means for coating the gypsum fiberboard panel 2 with a coating agent, for example a hydrophobic agent and/or a dust-binding agent.

(25) In the following, production, according to the invention, of a gypsum fiberboard panel 2, in particular continuous production, using the apparatus 1 according to the invention, will be described.

(26) Gypsum 14, fibers 15, and, if applicable, aggregates and/or additives and/or admixtures 16 in accordance with a composition to be produced are placed into the mixing device 4a. In the mixing device 4a, these raw materials are mixed to produce the mixture 13, in particular the dry mixture 13.

(27) In the method, a gypsum 14 made from natural gypsum, preferably building plaster or stucco, and/or technical gypsum, preferably FGD gypsum, and/or gypsum-like calcium sulfate modifications, preferably RC [recycled] gypsum, is used. In particular, FGD gypsum is used. Preferably, gypsum having a grain size of 1 μm to 1 mm, preferably of 10 to 200 μm is used.

(28) Fibers that contain cellulose, preferably recycled paper fibers and/or artificial mineral fibers, preferably glass fibers and/or rock wool fibers are used as fibers 15. In particular, recycled paper fibers are used. Preferably, fibers 15 having an average fiber length of 63 μm to 2 mm are used.

(29) In addition, usual aggregates, additives and/or admixtures can be used.

(30) Preferably, a mixture 13 having the following composition is produced in the mixing device 4a:

(31) TABLE-US-00001 Raw material Proportion [weight-%] Gypsum 75 to 85 Fibers  5 to 20 Aggregate  0 to 10 Additive  0 to 2

(32) The advancing speed V.sub.A of the screen belt 3a of the conveying device 3 in the advancing direction A is preferably set to 5 to 500 mm/s (depending upon the thickness of the mixture 13).

(33) The mixture 13 is applied to the screen belt 3a by means of the feed device 4b. Preferably, the mixture 13 is spread onto the screen belt 3a with a thickness or mixture height of 20 to 350 mm.

(34) The mixture 13 is conveyed into the pre-compaction device 5 for pre-compaction, through the passage opening 30 of the spray chamber 26, which faces the mixing device 4a.

(35) In the pre-compaction device 5, the free top side 13a of the mixture 13 is uniformly sprayed with the water mist 23, using the means 22. In this regard, the water mist 23 is preferably set in such a manner that the mixture 13 is sprayed with fine water droplets having an average droplet size of 0.1 to 60 μm, preferably 15 μm. In particular, aerosol cones 31 forming the water mist 23 and consisting of gas, for example nitrogen, or air and water particles, are produced using the mist nozzles 27. Preferably, in this regard, the aerosol cones 31 are produced with an air pressure of 2 to 4 bar, preferably 3 bar, and a liquid pressure of 1 to 3 bar, preferably 2 bar, and a jet angle of 40 to 80°, preferably 60°. Depending on the mixture height, the mixture 13 is sprayed with an amount of water of 1 to 10 l/h. For production of a panel thickness of 30 mm, the mixture is sprayed with an amount of water or amount of water mist of 7 l/h, for example.

(36) Preferably, a water/solid value w/s of 0.05 to 0.25, preferably of 0.1, is produced in the mixture 13, using the means 22 for spraying.

(37) In the pre-compaction device 5, a partial vacuum is furthermore applied to the underside 13b of the mixture 13, using the means 24, in particular at the same time with spraying of the mixture 13 with the water mist 23. With the partial vacuum, the water mist 23, i.e. the water particles contained in the water mist 23 are drawn into the mixture 13, and thereby the mixture 13 is compacted and made capable of absorbing water. Preferably, a partial vacuum of 5 to 20 mbar, preferably of 10 to 15 mbar, preferentially of 10 mbar is applied to the mixture 13 for pre-compaction. In particular, the partial vacuum is applied on the underside of the conveying means, so that the partial vacuum acts on the mixture 13 through the screen belt 3a.

(38) After pre-compaction, the mixture 13 is passed to the wetting device 6 or conveyed into the wetting device 6. In the wetting device 6, the mixture 13, in particular the top side 13a of the mixture, is wetted or watered with the setting water required for setting the gypsum/fiber mixture, by means of the water curtain 32. Preferably, in this regard, a water/solid value w/s of 0.4 to 0.6, preferably of 0.5, is produced.

(39) After wetting, the mixture 13 is conveyed into the post-compaction device 7 or the mixture 13 passes through the post-compaction device 7. A partial vacuum is applied to the underside 13b of the mixture 13, using the post-compaction device 7. The setting water is drawn into the mixture 13 with the partial vacuum, wherein the mixture 13 is further compacted or post-compacted. Preferably, a partial vacuum of 10 to 25 mbar, preferably of 15 to 20 mbar, preferentially of 20 mbar is applied to the mixture 13 for post-compaction. In particular, the partial vacuum is applied to the underside of the screen belt 3a, so that the partial vacuum is applied to the mixture 13 through the screen belt 3a. In particular, the partial vacuum is applied in such a manner that the amount of air drawn off to generate the partial vacuum is increased section by section along the underside of the screen belt, viewed in the advancing direction A.

(40) However, it also lies within the scope of the invention that wetting and post-compaction take place simultaneously, in particular that a device configured analogous to the pre-compaction device is used for wetting and post-compaction.

(41) The post-compacted mixture 13 is conveyed to the pressing device 8 and pressed to form a gypsum fiberboard panel strand having a thickness in accordance with the gypsum fiberboard panel 2 to be produced, using the means for pressing. Preferably, a pressure of 100 to 350 bar, in particular 300 bar is applied for pressing the mixture 13.

(42) The gypsum fiberboard panel strand is conveyed to the cutting device 9 and separated into individual gypsum fiberboard panels 2 using the means for disaggregation.

(43) The separated gypsum fiberboard panels 2 are conveyed into the drying device 10 and dried using the means for drying. Preferably, the gypsum fiberboard panels 2 are dried at a temperature of 80 to 260° C. for 40 to 100 minutes.

(44) If necessary, the gypsum fiberboard panels 2 are profiled and/or reworked in the finishing device 11. For example, the gypsum fiberboard panels 2 can be provided with sharp-edged or profiled edges, or an edge can be produced having a flattened region that runs toward the panel edge.

(45) After drying and finishing, the gypsum fiberboard panels 2 are coated with a coating agent, for example a hydrophobic agent or an agent for binding dust, in the coating device 12, if applicable.

(46) In advantageous manner, the gypsum fiberboard panels 2 described above are produced with the following dimensions and material properties: Thickness 6 to 50 mm, preferably 10 to 25 mm, preferentially 10 to 18 mm, Raw density according to DIN EN 15283-2 of 1000 to 1500 kg/m.sup.3, preferably of 1200 kg/m.sup.3, Bending strength according to DIN EN 15283-2 of 4 to 15 N/m.sup.2, preferably of 7 N/m.sup.2.

(47) In particular, one-part or one-piece gypsum fiberboard panels 2 having a panel thickness>25 mm can also be produced in reliable manner.

(48) Although only a few embodiments of the present invention have been shown and described, it is to be understood that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention.