US20200181022A1 - Gypsum fiber board and method for producing gypsum fiber boards - Google Patents
Gypsum fiber board and method for producing gypsum fiber boards Download PDFInfo
- Publication number
- US20200181022A1 US20200181022A1 US16/794,184 US202016794184A US2020181022A1 US 20200181022 A1 US20200181022 A1 US 20200181022A1 US 202016794184 A US202016794184 A US 202016794184A US 2020181022 A1 US2020181022 A1 US 2020181022A1
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- Prior art keywords
- hydrate
- calcium sulfate
- sulfate hemi
- relative
- gypsum fiber
- Prior art date
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- Abandoned
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- 229910052602 gypsum Inorganic materials 0.000 title claims abstract description 83
- 239000010440 gypsum Substances 0.000 title claims abstract description 83
- 239000011094 fiberboard Substances 0.000 title claims abstract description 51
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 20
- 239000000203 mixture Substances 0.000 claims abstract description 68
- 239000000835 fiber Substances 0.000 claims abstract description 43
- ZOMBKNNSYQHRCA-UHFFFAOYSA-J calcium sulfate hemihydrate Chemical compound O.[Ca+2].[Ca+2].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O ZOMBKNNSYQHRCA-UHFFFAOYSA-J 0.000 claims abstract description 40
- 239000000123 paper Substances 0.000 claims abstract description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 33
- 239000000463 material Substances 0.000 claims description 23
- 238000000034 method Methods 0.000 claims description 23
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 15
- 238000005469 granulation Methods 0.000 claims description 12
- 230000003179 granulation Effects 0.000 claims description 12
- 230000036571 hydration Effects 0.000 claims description 11
- 238000006703 hydration reaction Methods 0.000 claims description 11
- 238000002156 mixing Methods 0.000 claims description 7
- 150000004683 dihydrates Chemical class 0.000 claims description 3
- 239000000080 wetting agent Substances 0.000 claims description 3
- 230000000887 hydrating effect Effects 0.000 claims description 2
- 238000001035 drying Methods 0.000 abstract description 5
- 238000000227 grinding Methods 0.000 description 6
- 238000012545 processing Methods 0.000 description 5
- 239000010893 paper waste Substances 0.000 description 4
- 238000001354 calcination Methods 0.000 description 3
- 239000010419 fine particle Substances 0.000 description 3
- 239000011505 plaster Substances 0.000 description 3
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000000428 dust Substances 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 230000008092 positive effect Effects 0.000 description 2
- 238000003892 spreading Methods 0.000 description 2
- 238000009736 wetting Methods 0.000 description 2
- OYPRJOBELJOOCE-IGMARMGPSA-N Calcium-40 Chemical compound [40Ca] OYPRJOBELJOOCE-IGMARMGPSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 238000003801 milling Methods 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000011343 solid material Substances 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/14—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing calcium sulfate cements
- C04B28/145—Calcium sulfate hemi-hydrate with a specific crystal form
- C04B28/147—Calcium sulfate hemi-hydrate with a specific crystal form beta-hemihydrate
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B1/00—Producing shaped prefabricated articles from the material
- B28B1/52—Producing shaped prefabricated articles from the material specially adapted for producing articles from mixtures containing fibres, e.g. asbestos cement
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B1/00—Producing shaped prefabricated articles from the material
- B28B1/52—Producing shaped prefabricated articles from the material specially adapted for producing articles from mixtures containing fibres, e.g. asbestos cement
- B28B1/521—Producing shaped prefabricated articles from the material specially adapted for producing articles from mixtures containing fibres, e.g. asbestos cement from dry mixtures to which a setting agent is applied after forming
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B19/00—Machines or methods for applying the material to surfaces to form a permanent layer thereon
- B28B19/0092—Machines or methods for applying the material to surfaces to form a permanent layer thereon to webs, sheets or the like, e.g. of paper, cardboard
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B5/00—Producing shaped articles from the material in moulds or on moulding surfaces, carried or formed by, in or on conveyors irrespective of the manner of shaping
- B28B5/02—Producing shaped articles from the material in moulds or on moulding surfaces, carried or formed by, in or on conveyors irrespective of the manner of shaping on conveyors of the endless-belt or chain type
- B28B5/026—Producing shaped articles from the material in moulds or on moulding surfaces, carried or formed by, in or on conveyors irrespective of the manner of shaping on conveyors of the endless-belt or chain type the shaped articles being of indefinite length
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B11/00—Calcium sulfate cements
- C04B11/002—Mixtures of different CaSO4-modifications, e.g. plaster of Paris and anhydrite, used as cements
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B18/00—Use of agglomerated or waste materials or refuse as fillers for mortars, concrete or artificial stone; Treatment of agglomerated or waste materials or refuse, specially adapted to enhance their filling properties in mortars, concrete or artificial stone
- C04B18/04—Waste materials; Refuse
- C04B18/18—Waste materials; Refuse organic
- C04B18/24—Vegetable refuse, e.g. rice husks, maize-ear refuse; Cellulosic materials, e.g. paper, cork
- C04B18/241—Paper, e.g. waste paper; Paper pulp
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B24/00—Use of organic materials as active ingredients for mortars, concrete or artificial stone, e.g. plasticisers
- C04B24/04—Carboxylic acids; Salts, anhydrides or esters thereof
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/14—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing calcium sulfate cements
- C04B28/145—Calcium sulfate hemi-hydrate with a specific crystal form
- C04B28/146—Calcium sulfate hemi-hydrate with a specific crystal form alpha-hemihydrate
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
- C04B40/0028—Aspects relating to the mixing step of the mortar preparation
- C04B40/0039—Premixtures of ingredients
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2103/00—Function or property of ingredients for mortars, concrete or artificial stone
- C04B2103/10—Accelerators; Activators
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2103/00—Function or property of ingredients for mortars, concrete or artificial stone
- C04B2103/20—Retarders
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
- C04B2111/00612—Uses not provided for elsewhere in C04B2111/00 as one or more layers of a layered structure
- C04B2111/0062—Gypsum-paper board like materials
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/91—Use of waste materials as fillers for mortars or concrete
Definitions
- a method for producing gypsum fiber boards by the so-called Siempelkamp process is known for example from the publication DE. 2 257 827.
- a dry mixture of fibers and the mineral binder calcium sulfate hemi-hydrate is spread uniformly onto a continuously moving conveyor belt.
- Hydration water is added by netting the dry mixture before passing it through a continuously working hydraulic press in order to form an endless board which subsequently may be cut into a plurality of separate pieces.
- the hydration water is added to the dry mixture before compression of the latter and is absorbed by means of vacuum applied to the fiber gypsum mixture whereby a large portion of the water which remains in the endless compressed board still reacts with the plaster.
- the boards are dried and are supplied to further finishing stages, e.g., for grinding, further cutting, stacking, etc.
- the board thickness is dependent on the mass and the pouring height of the mixture of fibers and calcium sulfate hemi-hydrate applied onto the conveyor belt.
- the latter may no longer wetted sufficiently by the hydration water which is added prior to compression, even if the amount of water is further increased. This means that sometimes dry material remains on the conveyor belt after pressing which is not incorporated into the plaster board to be produced.
- a gypsum fiber board produced in a Siempelkamp dry-process comprising 75 wt % to 90 wt % (relative to the total dry mix) of calcium sulfate hemi-hydrate and 10 wt % to 25 wt % (relative to the total dry mix) paper fibers, wherein the calcium sulfate hemi-hydrate is a mixture of ⁇ -calcium sulfate hemi-hydrate and ⁇ -calcium sulfate hemi-hydrate, wherein the content of ⁇ -calcium sulfate hemi-hydrate in the mixture is at least 5 wt % (relative to the total calcium sulfate hemi-hydrate) is disclosed. Also disclosed is a method for producing a gypsum fiber board of a thickness of 23 mm in a Siempelkamp dry-process.
- FIG. 1 shows a schematic view of a Siempelkamp production plant according to prior art
- FIG. 2 shows water evacuation curves according to various mixing ratios of ⁇ -calcium sulfate hemi-hydrate and ⁇ -calcium sulfate hemi-hydrate;
- FIG. 3 shows water evacuation curves according to various granulations of ⁇ -calcium sulfate hemi-hydrate and ⁇ -calcium sulfate hemi-hydrate.
- the invention pertains to a gypsum fiber board and a method for producing gypsum fiber boards. It is an object of the present invention to improve methods for producing a gypsum fiber board and to provide a gypsum fiber board produced in such a process and in particular to a Siempelkamp production process which allows for producing gypsum fiber boards of more than 19 mm.
- a gypsum fiber board produced in a Si Zikamp process comprising 75 wt % to 90 wt % (relative to the total dry mix) of calcium sulfate hemi-hydrate and 10 wt % to 25 wt % (relative to the total dry mix) of paper fibers, wherein the calcium sulfate hemi-hydrate is a mixture of ⁇ -calcium sulfate hemi-hydrate and ⁇ -calcium sulfate hemi-hydrate, wherein the content of ⁇ -calcium sulfate hemi-hydrate in the mixture is at least 5 wt % (relative to the total calcium sulfate hemi-hydrate).
- the wettability which is to be understood to be the ability of the water to protrude the mixture of ⁇ -calcium sulfate hemi-hydrate and ⁇ -calcium sulfate hemi-hydrate may be increased.
- the wettability is increased such that the gypsum fiber board may be produced in a Siempelkamp process (of the identical applied vacuum pressure) with a thickness of up to 23 mm (i.e. a thickness of 25 mm before grinding).
- the content of ⁇ -calcium sulfate hemi-hydrate is at least 20 wt % (relative to the total calcium sulfate hemi-hydrate), in particular, about 30 wt % (relative to the total calcium sulfate hemi-hydrate).
- the content of ⁇ -calcium sulfate hemi-hydrate being preferably at least 50 wt % (relative to the total calcium sulfate hemi-hydrate), and in particular, about 60 wt % (relative to the total calcium sulfate hemi-hydrate)
- fiber boards may be produced having a thickness of more than 19 mm, specifically of 23 mm.
- the mixture of dry material further comprises retardant, in particular, citric acid.
- the mixture of dry material further comprises an accelerator; in particular, dehydrate which might originate from sawing or grinding.
- an accelerator in particular, dehydrate which might originate from sawing or grinding.
- the plaster may be modified so as to fulfill specific requirements of the intended application areas.
- the board has a thickness greater than 19 mm, in particular, of about 23 mm. This increased thickness renders a higher strength and stability to the board which in various implementations may be advantageous.
- the wettability of the gypsum fiber mixture and, thus, the thickness of the gypsum fiber board may be further increased by adaptation of the granulation. Specifically, it is advantageous, if gypsum fiber composition has no granulation below 1 ⁇ m which means that the share of granulation size below 1 ⁇ m is less than 10%.
- the wettability may be further improved by the appropriate selection of the fibers which are present in the dry mixture.
- wetting agents may be present in the gypsum fiber composition which influences the surface tension of the hydration water in order to even further increase the wettability.
- the finished board having a thickness of 23 mm has a bulk density of 1000 to 1500 kg/m 3 , in particular 1220 to 1390 kg/m 3 , and a weight per unit area of 23 to 35 kg/m 2 , in particular 28 to 32 kg/m 2 .
- a gypsum fiber board having an improved strength and stability compared to an 18 mm gypsum fiber board may be provided.
- a method for producing gypsum fiber boards comprising the steps of preparing a compressible mat of gypsum-containing material from a mixture comprising 75 wt % to 90 wt % (relative to the total dry mix) of calcium sulfate and 10 wt % to 25 wt % (relative to the total dry mix) of paper fibers, wherein the calcium sulfate hemi-hydrate is a mixture of ⁇ -calcium sulfate hemi-hydrate and ⁇ -calcium sulfate hemi-hydrate, wherein the content of ⁇ -calcium sulfate hemi-hydrate in the mixture is at least 5 wt % (relative to the total calcium sulfate hemi-hydrate); moving the dry compressible mat of gypsum-containing material on a conveyor belt to a hydration water tank; and hydrating the gypsum-containing material with hydration
- the step of preparing the compressible mat comprises mixing at least 20 wt % (relative to the total calcium sulfate hemi-hydrate) ⁇ -calcium sulfate hemi-hydrate, in particular, about 30 wt % (relative to the total calcium sulfate hemi-hydrate) with at least 50 wt % (relative to the total calcium sulfate hemi-hydrate), in particular, about 60 wt % (relative to the total calcium sulfate hemi-hydrate) of ⁇ -calcium sulfate hemi-hydrate.
- this composition allows for the production of gypsum fiber boards having a thickness of more than 19 mm.
- the method may further comprise a step of adding a retardant, in particular, citric acid, and/or a step of adding an accelerator, in particular, dehydrate as accelerator, in order to adjust the properties of the finished board to the intended application fields.
- a retardant in particular, citric acid
- an accelerator in particular, dehydrate as accelerator
- the thickness of the dry compressible mat of gypsum-containing material prior to adding water is within the range of 80 mm to 100 mm, in particular 85 mm to 95 mm.
- FIG. 1 is a schematic view of a Si Zikamp production plant 1 according to prior art for producing gypsum fiber boards in a dry Siempelkamp process.
- the production plant 1 comprises a paper processing device 2 for processing waste paper 16 .
- the production plant 1 comprises a sequence of processing stations 3 a to 3 d for preparing the calcium sulfate hemi-hydrate with 3 a indicating a station comprising a recycling device, 3 b indicating a station for processing (e.g., milling) the recycled material, 3 c indicating a gypsum reservoir for storing gypsum to be added from the reservoir 3 c to a calcination device 3 d in which the mixture of recycled and processed material is subjected to a calcination procedure together with the gypsum added from the reservoir 3 c in order to dehydrate the material.
- the accordingly processed paper fibers from the paper processing device 2 and the calcinated material from the calcination device 3 d are supplied to a mixing and spreading device 4 which then spreads the mixed gypsum fiber composition uniformly onto a continuously moving conveyor belt 5 .
- the weight per unit area of the gypsum fiber composition lies within the range of 25 to 28.5 kg/m 2 (for the dry material mixture) from which a gypsum fiber board having a thickness of 18 mm will result.
- the spread gypsum fiber composition now forms a mat 6 on the conveyor belt 5 having a height in the range of 75 to 87 mm.
- the mat 6 is carried further on the conveyor belt 5 , prior to being passed through a continuous hydraulic press 8 , it is hydrated by supplying hydration water from a tank 7 from above onto the top surface 9 of the mat 6 whereby the water is applied in excess. Then the mat 6 travels through the hydraulic press 8 such that the gypsum fiber composition is compressed to a board having a bulk thickness of about 25 mm with a density in the range of 1220 to 1390 kg/m 3 . After leaving the hydraulic press 8 as an endless board, the latter is being grinded to a thickness of 23 mm and cut to single pieces having a predetermined length by means of a sawing device 9 .
- the cut pieces or boards 10 are then supplied to a drying furnace 11 followed by a grinding device 12 and a primer device 13 .
- the finished gypsum fiber boards 10 are then stacked on pallets 14 on which they may be loaded into a vehicle 15 .
- the velocity of the conveyor belt 5 for a board 10 thus produced is 120 mm/s.
- the gypsum fiber boards 10 produced according to prior art have a maximum thickness of 19 mm.
- the wettability can be improved, and thus, the thickness of the gypsum fiber board 10 to be produced may be increased above 19 mm by specific selection of the gypsum and/or the fibers.
- Wettability is the ability of the material to let the water protrude the mixture of ⁇ -calcium sulfate hemi-hydrate and ⁇ -calcium sulfate hemi-hydrate.
- a liquid may wet the surface more or less.
- the initial gypsum fiber composition comprises 10 to 25 wt % relative to the total dry mix of paper fibers from waste paper, 75 to 90 wt % relative to the total dry mix.
- the calcium sulfate hemi-hydrate is a mixture of ⁇ -calcium sulfate hemi-hydrate and ⁇ -calcium sulfate hemi-hydrate. Specifically, the content of ⁇ -calcium sulfate hemi-hydrate in the mixture is at least 5 wt % (relative to the calcium sulfate hemi-hydrate).
- the gypsum fiber composition comprises citric acid as retardant and dihydrate (grinding dust or sawing dust) as accelerator (i.e. 0.5% to 5%).
- the fibers are filtered prior-to being added to the mixing and spreading device 4 .
- a further positive effect as to wettability and, thus, thickness of the gypsum fiber board may be achieved by the specific selection of the type of waste paper. For example, newspapers have a low content of fine particles, journals, magazines and catalogues have a higher content of fine particles. To achieve the best results, waste paper having a low content of fine particles should be selected.
- a further improvement can be yet achieved when adding a wetting agent to influence the surface tension of the hydration water added to the dry gypsum fiber composition from the tank 7 .
- the gypsum fiber composition according to an embodiment of the invention as outlined above may then be processed in the plant 1 as outlined above.
- the height of the mat 6 prior to adding hydration water from the tank 7 lies within a range 80 mm to 100 mm, in particular 85 mm to 95 mm, when producing a gypsum fiber board 10 having a thickness of 23 mm (which is 25 mm before grinding).
- the weight per unit area for such a gypsum fiber composition 10 lies within the range of 28 to 32 kg/m 2 whereas the bulk density of the finished gypsum fiber boards 10 according to the embodiment lies within the range of 1000 to 1500 kg/m 3 .
- FIG. 2 shows water evacuation curves according to various mixing ratios of ⁇ -calcium sulfate hemi-hydrate and ⁇ -calcium sulfate hemi-hydrate to prove the effect of that an increased portion of ⁇ -calcium sulfate hemi-hydrate has a positive effect to the wetting, in particular, to the evacuation.
- the curves have been taken by means of the following experimental set-up.
- a vacuum pump has been arranged at a glass container provided with a funnel and a sieve (and paper filter) at its upper open end.
- the composition i.e., various mixtures containing ⁇ -calcium sulfate hemi-hydrate and ⁇ -calcium sulfate hemi-hydrate in different ratios, is introduced into the funnel.
- the pump creates a uniform vacuum (i.e. 0.5 bar) and water is sucked from the composition whereby the time is measured.
- the weight of the water sucked from the composition is measured in the glass container.
- curve 1 shows a ratio of ⁇ -calcium sulfate hemi-hydrate to ⁇ -calcium sulfate hemi-hydrate of 60:40 (60% ⁇ -calcium sulfate hemi-hydrate/40% ⁇ -calcium sulfate hemi-hydrate)
- curve 2 shows a ratio of ⁇ -calcium sulfate hemi-hydrate to ⁇ -calcium sulfate hemi-hydrate of 40:60 (40% ⁇ -calcium sulfate hemi-hydrate/60% ⁇ -calcium sulfate hemi-hydrate)
- curves 3 respectively show a ratio of ⁇ -calcium sulfate hemi-hydrate to ⁇ -calcium sulfate hemi-hydrate of 20:80 (20% ⁇ -calcium sulfate hemi-hydrate/80% ⁇ -calcium sulfate hemi-hydrate),
- ⁇ -calcium sulfate hemi-hydrate seems to have better properties concerning the wetting as more water can be sucked out of the compositions containing more ⁇ -calcium sulfate hemi-hydrate.
- ⁇ -calcium sulfate hemi-hydrate has the better properties concerning the absorption of water as more water can be sucked out of the compositions containing more ⁇ -calcium sulfate hemi-hydrate. This is caused by the crystal properties of the ⁇ -calcium sulfate hemi-hydrate, in particular of the compact geometry thereof.
- FIG. 3 shows water evacuation curves according to various granulations of ⁇ -calcium sulfate hemi-hydrate.
- Curves 1 and 2 respectively show water evacuation curves for ⁇ -calcium sulfate hemi-hydrate with different granulation wherein curve 1 is the coarser granulation compared to the ⁇ -calcium sulfate hemi-hydrate represented in curve 2 .
- Curves 3 and 4 show water evacuation characteristics of different ⁇ -calcium sulfate hemi-hydrate materials originating from different plants.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Mechanical Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Inorganic Chemistry (AREA)
- Crystallography & Structural Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Civil Engineering (AREA)
- Environmental & Geological Engineering (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
- Producing Shaped Articles From Materials (AREA)
- Paper (AREA)
Abstract
A gypsum fiber board produced in a Siempelkamp dry-process, comprising 75 wt % to 90 wt % (relative to the total dry mix) of calcium sulfate hemi-hydrate and 10 wt % to 25 wt % (relative to the total dry mix) paper fibers, wherein the calcium sulfate hemi-hydrate is a mixture of α-calcium sulfate hemi-hydrate and β-calcium sulfate hemi-hydrate, wherein the content of α-calcium sulfate hemi-hydrate in the mixture is at least 5 wt % (relative to the total calcium sulfate hemi-hydrate) is disclosed. Also disclosed is a method for producing a gypsum fiber board of a thickness of 23 mm in a Siempelkamp dry-process.
Description
- This patent application is a continuation of application Ser. No. 15/628,596 filed Jun. 20, 2017 titled “Gypsum Fiber Board and Method for Producing Gypsum Fiber Boards,” which claims priority to international application number PCT/EP2014/003457 filed Dec. 22, 2014 titled “Gypsum Fiber Board and Method for Producing Gypsum Fiber Boards”. The subject matter of application Ser. No. 15/628,596 and international application number PCT/EP2014/003457 is hereby incorporated by reference in its entirety.
- Not Applicable.
- Not Applicable.
- In prior art, a method for producing gypsum fiber boards by the so-called Siempelkamp process is known for example from the publication DE. 2 257 827. According to this process, a dry mixture of fibers and the mineral binder calcium sulfate hemi-hydrate is spread uniformly onto a continuously moving conveyor belt. Hydration water is added by netting the dry mixture before passing it through a continuously working hydraulic press in order to form an endless board which subsequently may be cut into a plurality of separate pieces. The hydration water is added to the dry mixture before compression of the latter and is absorbed by means of vacuum applied to the fiber gypsum mixture whereby a large portion of the water which remains in the endless compressed board still reacts with the plaster. After the setting process is completed, the boards are dried and are supplied to further finishing stages, e.g., for grinding, further cutting, stacking, etc.
- Today with the Siempelkamp process it is only possible to form gypsum fiber boards having a thickness of up to 19 mm at the maximum. Basically, the board thickness is dependent on the mass and the pouring height of the mixture of fibers and calcium sulfate hemi-hydrate applied onto the conveyor belt. However, at a certain mass and/or pouring height of the dry mixture of fibers and calcium sulfate hemi-hydrate, the latter may no longer wetted sufficiently by the hydration water which is added prior to compression, even if the amount of water is further increased. This means that sometimes dry material remains on the conveyor belt after pressing which is not incorporated into the plaster board to be produced.
- In prior art, a solution for increasing the thickness of a board produced on a Siempelkamp production plant above the limit of 19 mm has not yet been found. As already mentioned above, neither the increase of water to be added nor any modifications to the machines used for the above described Siempelkamp production process have rendered a board thickness of more than 19 mm.
- This Summary is provided to introduce a selection of disclosed concepts in a simplified form that are further described below in the Detailed Description including the drawings provided. This Summary is not intended to identify key features or essential features of the claimed subject matter. Nor is this Summary intended to be used to limit the claimed subject matter's scope.
- In one embodiment, a gypsum fiber board produced in a Siempelkamp dry-process, comprising 75 wt % to 90 wt % (relative to the total dry mix) of calcium sulfate hemi-hydrate and 10 wt % to 25 wt % (relative to the total dry mix) paper fibers, wherein the calcium sulfate hemi-hydrate is a mixture of α-calcium sulfate hemi-hydrate and β-calcium sulfate hemi-hydrate, wherein the content of α-calcium sulfate hemi-hydrate in the mixture is at least 5 wt % (relative to the total calcium sulfate hemi-hydrate) is disclosed. Also disclosed is a method for producing a gypsum fiber board of a thickness of 23 mm in a Siempelkamp dry-process.
-
FIG. 1 shows a schematic view of a Siempelkamp production plant according to prior art; -
FIG. 2 shows water evacuation curves according to various mixing ratios of α-calcium sulfate hemi-hydrate and β-calcium sulfate hemi-hydrate; and -
FIG. 3 shows water evacuation curves according to various granulations of α-calcium sulfate hemi-hydrate and β-calcium sulfate hemi-hydrate. - The invention pertains to a gypsum fiber board and a method for producing gypsum fiber boards. It is an object of the present invention to improve methods for producing a gypsum fiber board and to provide a gypsum fiber board produced in such a process and in particular to a Siempelkamp production process which allows for producing gypsum fiber boards of more than 19 mm.
- This object is solved by a gypsum fiber board and a method for producing a gypsum fiber boards having the features of the respective independent claim. Preferred embodiments of the invention are defined by the respective dependent claims.
- According to the invention, a gypsum fiber board produced in a Siempelkamp process is provided comprising 75 wt % to 90 wt % (relative to the total dry mix) of calcium sulfate hemi-hydrate and 10 wt % to 25 wt % (relative to the total dry mix) of paper fibers, wherein the calcium sulfate hemi-hydrate is a mixture of α-calcium sulfate hemi-hydrate and β-calcium sulfate hemi-hydrate, wherein the content of α-calcium sulfate hemi-hydrate in the mixture is at least 5 wt % (relative to the total calcium sulfate hemi-hydrate). By the specific selection of the proportion of α-calcium sulfate hemi-hydrate, β-calcium sulfate hemi-hydrate, and/or the fibers, the wettability which is to be understood to be the ability of the water to protrude the mixture of α-calcium sulfate hemi-hydrate and β-calcium sulfate hemi-hydrate may be increased. Specifically, by adding α-calcium sulfate hemi-hydrate in a proportion of at least 5 wt % (relative to the total calcium sulfate hemi-hydrate), the wettability is increased such that the gypsum fiber board may be produced in a Siempelkamp process (of the identical applied vacuum pressure) with a thickness of up to 23 mm (i.e. a thickness of 25 mm before grinding).
- According to a preferred embodiment of the invention, the content of α-calcium sulfate hemi-hydrate is at least 20 wt % (relative to the total calcium sulfate hemi-hydrate), in particular, about 30 wt % (relative to the total calcium sulfate hemi-hydrate). With the content of β-calcium sulfate hemi-hydrate being preferably at least 50 wt % (relative to the total calcium sulfate hemi-hydrate), and in particular, about 60 wt % (relative to the total calcium sulfate hemi-hydrate), fiber boards may be produced having a thickness of more than 19 mm, specifically of 23 mm.
- According to a further preferred embodiment, the mixture of dry material further comprises retardant, in particular, citric acid.
- According to a still further preferred embodiment, the mixture of dry material further comprises an accelerator; in particular, dehydrate which might originate from sawing or grinding. By means of specific additives, as for example, retardants or accelerators, the plaster may be modified so as to fulfill specific requirements of the intended application areas.
- Preferably, the board has a thickness greater than 19 mm, in particular, of about 23 mm. This increased thickness renders a higher strength and stability to the board which in various implementations may be advantageous.
- The wettability of the gypsum fiber mixture and, thus, the thickness of the gypsum fiber board may be further increased by adaptation of the granulation. Specifically, it is advantageous, if gypsum fiber composition has no granulation below 1 μm which means that the share of granulation size below 1 μm is less than 10%.
- Moreover, the wettability may be further improved by the appropriate selection of the fibers which are present in the dry mixture. Preferably, there should be no fibers present in the having a length of less than 1 μm. It is specifically advantageous, if the fibers have a short and thin morphology rather than being long and thick. It is also preferred, if the content of fibers having a length greater than 90 μm is less than 65 wt %.
- Further, wetting agents may be present in the gypsum fiber composition which influences the surface tension of the hydration water in order to even further increase the wettability.
- Preferably, the finished board having a thickness of 23 mm has a bulk density of 1000 to 1500 kg/m3, in particular 1220 to 1390 kg/m3, and a weight per unit area of 23 to 35 kg/m2, in particular 28 to 32 kg/m2. Thus, a gypsum fiber board having an improved strength and stability compared to an 18 mm gypsum fiber board may be provided. According to the present invention, a method for producing gypsum fiber boards is also provided comprising the steps of preparing a compressible mat of gypsum-containing material from a mixture comprising 75 wt % to 90 wt % (relative to the total dry mix) of calcium sulfate and 10 wt % to 25 wt % (relative to the total dry mix) of paper fibers, wherein the calcium sulfate hemi-hydrate is a mixture of α-calcium sulfate hemi-hydrate and β-calcium sulfate hemi-hydrate, wherein the content of α-calcium sulfate hemi-hydrate in the mixture is at least 5 wt % (relative to the total calcium sulfate hemi-hydrate); moving the dry compressible mat of gypsum-containing material on a conveyor belt to a hydration water tank; and hydrating the gypsum-containing material with hydration water added from above to the surface of the mat in excess prior to passing the gypsum-containing material through a continuous press to form an endless gypsum fiber board having a thickness greater than 19 mm. By using the specific composition, it is possible to produce a gypsum fiber board with an increased thickness in a Siempelkamp process, specifically, in a Siempelkamp production plant.
- Preferably, the step of preparing the compressible mat comprises mixing at least 20 wt % (relative to the total calcium sulfate hemi-hydrate) α-calcium sulfate hemi-hydrate, in particular, about 30 wt % (relative to the total calcium sulfate hemi-hydrate) with at least 50 wt % (relative to the total calcium sulfate hemi-hydrate), in particular, about 60 wt % (relative to the total calcium sulfate hemi-hydrate) of β-calcium sulfate hemi-hydrate. As mentioned above, this composition allows for the production of gypsum fiber boards having a thickness of more than 19 mm.
- The method may further comprise a step of adding a retardant, in particular, citric acid, and/or a step of adding an accelerator, in particular, dehydrate as accelerator, in order to adjust the properties of the finished board to the intended application fields.
- It is also preferably to adjust the granulation of the gypsum fiber composition so as to be above 1 μm, in order to further enhance the wettability and thus, enable production of gypsum fiber boards having a thickness of greater than 19 mm.
- According to still a further embodiment of the method, the thickness of the dry compressible mat of gypsum-containing material prior to adding water is within the range of 80 mm to 100 mm, in particular 85 mm to 95 mm.
-
FIG. 1 is a schematic view of a Siempelkamp production plant 1 according to prior art for producing gypsum fiber boards in a dry Siempelkamp process. The production plant 1 comprises a paper processing device 2 for processingwaste paper 16. Further, the production plant 1 comprises a sequence of processing stations 3 a to 3 d for preparing the calcium sulfate hemi-hydrate with 3 a indicating a station comprising a recycling device, 3 b indicating a station for processing (e.g., milling) the recycled material, 3 c indicating a gypsum reservoir for storing gypsum to be added from thereservoir 3 c to acalcination device 3 d in which the mixture of recycled and processed material is subjected to a calcination procedure together with the gypsum added from thereservoir 3 c in order to dehydrate the material. The accordingly processed paper fibers from the paper processing device 2 and the calcinated material from thecalcination device 3 d are supplied to a mixing and spreading device 4 which then spreads the mixed gypsum fiber composition uniformly onto a continuously moving conveyor belt 5. According to processes known from prior art, the weight per unit area of the gypsum fiber composition lies within the range of 25 to 28.5 kg/m2 (for the dry material mixture) from which a gypsum fiber board having a thickness of 18 mm will result. The spread gypsum fiber composition now forms a mat 6 on the conveyor belt 5 having a height in the range of 75 to 87 mm. Then, as the mat 6 is carried further on the conveyor belt 5, prior to being passed through a continuous hydraulic press 8, it is hydrated by supplying hydration water from a tank 7 from above onto the top surface 9 of the mat 6 whereby the water is applied in excess. Then the mat 6 travels through the hydraulic press 8 such that the gypsum fiber composition is compressed to a board having a bulk thickness of about 25 mm with a density in the range of 1220 to 1390 kg/m3. After leaving the hydraulic press 8 as an endless board, the latter is being grinded to a thickness of 23 mm and cut to single pieces having a predetermined length by means of a sawing device 9. The cut pieces orboards 10 are then supplied to a dryingfurnace 11 followed by a grindingdevice 12 and a primer device 13. The finishedgypsum fiber boards 10 are then stacked onpallets 14 on which they may be loaded into a vehicle 15. The velocity of the conveyor belt 5 for aboard 10 thus produced is 120 mm/s. As already mentioned above, thegypsum fiber boards 10 produced according to prior art have a maximum thickness of 19 mm. - According to the present invention, the wettability can be improved, and thus, the thickness of the
gypsum fiber board 10 to be produced may be increased above 19 mm by specific selection of the gypsum and/or the fibers. Wettability, as already mentioned above, is the ability of the material to let the water protrude the mixture of α-calcium sulfate hemi-hydrate and β-calcium sulfate hemi-hydrate. Depending on which liquid is used, and on the material of the corresponding surface of solid material as well as its structure, e.g., with respect to its roughness, a liquid may wet the surface more or less. Thus, in order to obtain agypsum fiber board 10 according to an embodiment of the present invention having a thickness of more than 19 mm, the initial gypsum fiber composition comprises 10 to 25 wt % relative to the total dry mix of paper fibers from waste paper, 75 to 90 wt % relative to the total dry mix. The calcium sulfate hemi-hydrate is a mixture of α-calcium sulfate hemi-hydrate and β-calcium sulfate hemi-hydrate. Specifically, the content of α-calcium sulfate hemi-hydrate in the mixture is at least 5 wt % (relative to the calcium sulfate hemi-hydrate). Further, the gypsum fiber composition comprises citric acid as retardant and dihydrate (grinding dust or sawing dust) as accelerator (i.e. 0.5% to 5%). - According to a preferred embodiment of the invention, 30 wt % of α-calcium sulfate hemi-hydrate and 60 wt % of β-calcium sulfate hemi-hydrate are mixed in the initial composition. Further, the granulation should not contain grain sizes below 1 μm. Moreover, a further improvement of the wettability is achieved, if the fiber particles are larger than 1 μm. Specifically, short and thick or long and thin fibers improve the results with respect to wettability. Also, fibers larger than 90 μm should only be present in a proportion of 65% or less. To obtain the optimal fiber configuration in the gypsum fiber composition, the fibers are filtered prior-to being added to the mixing and spreading device 4.
- A further positive effect as to wettability and, thus, thickness of the gypsum fiber board, may be achieved by the specific selection of the type of waste paper. For example, newspapers have a low content of fine particles, journals, magazines and catalogues have a higher content of fine particles. To achieve the best results, waste paper having a low content of fine particles should be selected.
- A further improvement can be yet achieved when adding a wetting agent to influence the surface tension of the hydration water added to the dry gypsum fiber composition from the tank 7. The gypsum fiber composition according to an embodiment of the invention as outlined above may then be processed in the plant 1 as outlined above. However, the height of the mat 6 prior to adding hydration water from the tank 7 lies within a range 80 mm to 100 mm, in particular 85 mm to 95 mm, when producing a
gypsum fiber board 10 having a thickness of 23 mm (which is 25 mm before grinding). Further, the weight per unit area for such agypsum fiber composition 10 lies within the range of 28 to 32 kg/m2 whereas the bulk density of the finishedgypsum fiber boards 10 according to the embodiment lies within the range of 1000 to 1500 kg/m3. -
FIG. 2 shows water evacuation curves according to various mixing ratios of α-calcium sulfate hemi-hydrate and β-calcium sulfate hemi-hydrate to prove the effect of that an increased portion of α-calcium sulfate hemi-hydrate has a positive effect to the wetting, in particular, to the evacuation. The curves have been taken by means of the following experimental set-up. A vacuum pump has been arranged at a glass container provided with a funnel and a sieve (and paper filter) at its upper open end. The composition, i.e., various mixtures containing α-calcium sulfate hemi-hydrate and β-calcium sulfate hemi-hydrate in different ratios, is introduced into the funnel. The pump creates a uniform vacuum (i.e. 0.5 bar) and water is sucked from the composition whereby the time is measured. The weight of the water sucked from the composition is measured in the glass container. - The diagram of the water evacuation over time, the amount of water sucked through the material over time, curve 1 shows a ratio of α-calcium sulfate hemi-hydrate to β-calcium sulfate hemi-hydrate of 60:40 (60% α-calcium sulfate hemi-hydrate/40% β-calcium sulfate hemi-hydrate), curve 2 shows a ratio of α-calcium sulfate hemi-hydrate to β-calcium sulfate hemi-hydrate of 40:60 (40% α-calcium sulfate hemi-hydrate/60% β-calcium sulfate hemi-hydrate), curves 3 respectively show a ratio of α-calcium sulfate hemi-hydrate to β-calcium sulfate hemi-hydrate of 20:80 (20% α-calcium sulfate hemi-hydrate/80% β-calcium sulfate hemi-hydrate), curve 4 respectively shows a curve for 100% β-calcium sulfate hemi-hydrate.
- As can be seen from the diagram shown in
FIG. 2 , α-calcium sulfate hemi-hydrate seems to have better properties concerning the wetting as more water can be sucked out of the compositions containing more α-calcium sulfate hemi-hydrate. α-calcium sulfate hemi-hydrate has the better properties concerning the absorption of water as more water can be sucked out of the compositions containing more α-calcium sulfate hemi-hydrate. This is caused by the crystal properties of the α-calcium sulfate hemi-hydrate, in particular of the compact geometry thereof. -
FIG. 3 shows water evacuation curves according to various granulations of α-calcium sulfate hemi-hydrate. The same experimental set-up has been used as explained above in connection withFIG. 2 . Curves 1 and 2 respectively show water evacuation curves for α-calcium sulfate hemi-hydrate with different granulation wherein curve 1 is the coarser granulation compared to the α-calcium sulfate hemi-hydrate represented in curve 2.Curves 3 and 4 show water evacuation characteristics of different β-calcium sulfate hemi-hydrate materials originating from different plants.
Claims (19)
1. Gypsum fiber board produced in a Siempelkamp process, comprising 75 wt % to 90 wt %, relative to the total dry mix, of calcium sulfate hemi-hydrate and 10 wt % to 25 wt %, relative to the total dry mix, paper fibers, wherein the calcium sulfate hemi-hydrate is a mixture of α-calcium sulfate hemi-hydrate and β-calcium sulfate hemi-hydrate, wherein the content of α-calcium sulfate hemi-hydrate is at least 5 wt %, relative to the total calcium sulfate hemi-hydrate.
2. Gypsum fiber board according to claim 1 , wherein the content of α-calcium sulfate hemi-hydrate is at least 20 wt %, relative to the total calcium sulfate hemi-hydrate, in particular, about 30 wt %, relative to the total calcium sulfate hemi-hydrate.
3. Gypsum fiber board according to claim 1 , wherein the content of β-calcium sulfate hemi-hydrate is at least 50 wt %, relative to the total calcium sulfate hemi-hydrate, in particular, about 60 wt %, relative to the total calcium sulfate hemi-hydrate.
4. Gypsum fiber board according to claim 1 , further comprising retardant, in particular, citric acid.
5. Gypsum fiber board according to claim 1 , further comprising an accelerator, in particular, dihydrate.
6. Gypsum fiber board according to claim 1 , wherein the board has a thickness greater than 19 mm, in particular, of about 23 mm.
7. Gypsum fiber board according to claim 1 , wherein a portion of less than 90% in particular less than 70% of the gypsum fiber composition has a granulation above 1 μm.
8. Gypsum fiber board according to according to claim 1 , wherein the fibers have a minimum length of 1 μm, and wherein the content of fibers having a length greater than 90 μm is less than 45 wt %, relative to the total amount of paper fibers.
9. Gypsum fiber board according to claim 1 , further comprising wetting agents.
10. Gypsum fiber board according to claim 1 , wherein the finished board has a bulk density within the range of 1000 to 1500 kg/m3, in particular 1220 to 1390 kg/m3, and a weight per unit area in the range of 25 to 35 kg/m2, in particular 28 to 32 kg/m2.
11. A method for producing gypsum fiber boards, comprising the steps of:
preparing a compressible mat of gypsum-containing material from a mixture comprising 75 wt % to 90 wt %, relative to the total dry mix, of calcium sulfate hemi-hydrate and 10 wt % to 25 wt %, relative to the total dry mix, of paper fibers, wherein the calcium sulfate hemi-hydrate is a mixture of α-calcium sulfate hemi-hydrate and β-calcium sulfate hemi-hydrate, wherein the content of α-calcium sulfate hemi-hydrate in the mixture is at least 10 wt %, relative to the total calcium sulfate hemi-hydrate;
moving the dry compressible mat of gypsum-containing material on a conveyor belt to a hydration water tank, and
hydrating the gypsum-containing material with hydration water added from above to the top surface of the mat in excess prior to passing the gypsum-containing material through a continuous press to form an endless gypsum fiber board having a thickness greater than 19 mm.
12. The method according to claim 11 , wherein the step of preparing the compressible mat comprises mixing at least 20 wt %, relative to the total calcium sulfate hemi-hydrate, of α-calcium sulfate hemi-hydrate, with a least 50 wt %, relative to the total calcium sulfate hemi-hydrate, of β-calcium sulfate hemi-hydrate.
13. The method according to claim 11 , wherein the step of preparing the compressible mat comprises mixing about 30 wt %, relative to the total calcium sulfate hemi-hydrate, of α-calcium sulfate hemi-hydrate with about 60 wt %, relative to the total calcium sulfate hemi-hydrate, of β-calcium sulfate hemi-hydrate.
14. The method according to claim 11 , further comprising a step of adding a retardant and/or a step of adding an accelerator.
15. The method according to claim 11 , further comprising a step of adding a citric acid retardant and/or a step of adding an a coated dihydrate accelerator.
16. The method according to claim 11 , wherein the granulation of less than 90% of the gypsum fiber composition is above 1 μm.
17. The method according to claim 11 , wherein the granulation of less than 70% of the gypsum fiber composition is above 1 μm.
18. The method according to claim 11 , wherein the thickness of the dry compressible mat of gypsum-containing material prior to adding water is within the range of 80 mm to 100 mm, in particular 85 mm to 95 mm.
19. The method according to claim 11 , wherein the thickness of the dry compressible mat of gypsum-containing material prior to adding water is within the range of 85 mm to 95 mm.
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US16/794,184 US20200181022A1 (en) | 2014-12-22 | 2020-02-18 | Gypsum fiber board and method for producing gypsum fiber boards |
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PCT/EP2014/003457 WO2016101968A1 (en) | 2014-12-22 | 2014-12-22 | Gypsum fiber board and method for producing gypsum fiber boards |
US15/628,596 US10562817B2 (en) | 2014-12-22 | 2017-06-20 | Gypsum fiber board and method for producing gypsum fiber boards |
US16/794,184 US20200181022A1 (en) | 2014-12-22 | 2020-02-18 | Gypsum fiber board and method for producing gypsum fiber boards |
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PT3383606T (en) * | 2015-11-30 | 2021-04-09 | Knauf Gips Kg | Sound-absorbing gypsum fibre board and method for manufacturing such a gypsum fibre board |
DE102018218512B4 (en) * | 2018-10-29 | 2021-11-11 | James Hardie Europe Gmbh | Method and device for producing a plasterboard |
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DE2257827A1 (en) * | 1972-11-25 | 1974-06-06 | Siempelkamp Gmbh & Co | PROCESS AND INSTALLATION FOR THE PRODUCTION OF PANELS FROM FIBERS, IN PARTICULAR PAPER FIBERS, AND A HYDRAULIC BINDING AGENT, IN PARTICULAR PLASTER |
JPH0255255A (en) * | 1988-08-19 | 1990-02-23 | Tokuyama Soda Co Ltd | Gypsum composition |
DE3903641A1 (en) * | 1989-02-08 | 1990-08-09 | Fulgurit Baustoffe Gmbh | METHOD FOR PRODUCING PLASTER FIBER PANELS |
DE4008084A1 (en) * | 1990-03-14 | 1991-09-19 | Pro Mineral Ges | METHOD FOR PRODUCING PLASTER PANELS, ESPECIALLY OF FLOOR PLATES |
DE4222872C2 (en) * | 1991-08-09 | 1996-01-25 | Siempelkamp Gmbh & Co | Three-layer gypsum-based building material board and manufacturing method |
DE4129466A1 (en) * | 1991-09-05 | 1993-03-11 | Bold Joerg | METHOD FOR PRODUCING PLASTER PANELS AFTER A SEMI-DRYING PROCESS |
DE19534326C2 (en) * | 1995-09-15 | 2001-12-06 | Siempelkamp Gmbh & Co Kg G | Process for the production of gypsum fiber boards of homogeneous hydration and homogeneous density in a continuous press |
DE19912847C2 (en) * | 1999-03-22 | 2001-05-23 | Lindner Ag | Gypsum fiber blend and process for making high strength gypsum fiber boards |
US6409824B1 (en) * | 2000-04-25 | 2002-06-25 | United States Gypsum Company | Gypsum compositions with enhanced resistance to permanent deformation |
US6805741B1 (en) * | 2003-03-27 | 2004-10-19 | United States Gypsum Company | Ready-mixed setting-type composition and related kit |
DE10336569B4 (en) * | 2003-08-08 | 2005-07-21 | Siempelkamp Handling Systeme Gmbh & Co | Method for producing fire-resistant gypsum fiberboards and apparatus for carrying out a method for producing fire-resistant gypsum fiberboards |
EP2671854A1 (en) * | 2012-06-06 | 2013-12-11 | Etex Dryco SAS | Method for stabilizing beta-hemihydrate plaster |
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