EP1874707A1 - Procedes et systemes de preparation d une boue acceleratrice resistante a la chaleur et d ajout de la boue acceleratrice a une dispersion aqueuse de gypse calcine apres l'etape de melange - Google Patents

Procedes et systemes de preparation d une boue acceleratrice resistante a la chaleur et d ajout de la boue acceleratrice a une dispersion aqueuse de gypse calcine apres l'etape de melange

Info

Publication number
EP1874707A1
EP1874707A1 EP05741113A EP05741113A EP1874707A1 EP 1874707 A1 EP1874707 A1 EP 1874707A1 EP 05741113 A EP05741113 A EP 05741113A EP 05741113 A EP05741113 A EP 05741113A EP 1874707 A1 EP1874707 A1 EP 1874707A1
Authority
EP
European Patent Office
Prior art keywords
hra
discharge apparatus
mixing device
slurry
liquid medium
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP05741113A
Other languages
German (de)
English (en)
Inventor
James R. Wittbold
Brent Groza
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
United States Gypsum Co
Original Assignee
United States Gypsum Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by United States Gypsum Co filed Critical United States Gypsum Co
Publication of EP1874707A1 publication Critical patent/EP1874707A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B28WORKING CEMENT, CLAY, OR STONE
    • B28BSHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B17/00Details of, or accessories for, apparatus for shaping the material; Auxiliary measures taken in connection with such shaping
    • B28B17/02Conditioning the material prior to shaping
    • B28B17/023Conditioning gypsum
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01FMIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F23/00Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
    • B01F23/50Mixing liquids with solids
    • B01F23/53Mixing liquids with solids using driven stirrers
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01FMIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F23/00Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
    • B01F23/50Mixing liquids with solids
    • B01F23/59Mixing systems, i.e. flow charts or diagrams
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01FMIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F25/00Flow mixers; Mixers for falling materials, e.g. solid particles
    • B01F25/30Injector mixers
    • B01F25/31Injector mixers in conduits or tubes through which the main component flows
    • B01F25/312Injector mixers in conduits or tubes through which the main component flows with Venturi elements; Details thereof
    • B01F25/3124Injector mixers in conduits or tubes through which the main component flows with Venturi elements; Details thereof characterised by the place of introduction of the main flow
    • B01F25/31243Eductor or eductor-type venturi, i.e. the main flow being injected through the venturi with high speed in the form of a jet
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B28WORKING CEMENT, CLAY, OR STONE
    • B28CPREPARING CLAY; PRODUCING MIXTURES CONTAINING CLAY OR CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28C7/00Controlling the operation of apparatus for producing mixtures of clay or cement with other substances; Supplying or proportioning the ingredients for mixing clay or cement with other substances; Discharging the mixture
    • B28C7/04Supplying or proportioning the ingredients
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B28/00Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
    • C04B28/14Compositions 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
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B40/00Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
    • C04B40/0028Aspects relating to the mixing step of the mortar preparation
    • C04B40/0039Premixtures of ingredients
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01FMIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F25/00Flow mixers; Mixers for falling materials, e.g. solid particles
    • B01F25/30Injector mixers
    • B01F25/31Injector mixers in conduits or tubes through which the main component flows
    • B01F25/312Injector mixers in conduits or tubes through which the main component flows with Venturi elements; Details thereof
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01FMIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F27/00Mixers with rotary stirring devices in fixed receptacles; Kneaders
    • B01F27/80Mixers with rotary stirring devices in fixed receptacles; Kneaders with stirrers rotating about a substantially vertical axis
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01FMIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F35/00Accessories for mixers; Auxiliary operations or auxiliary devices; Parts or details of general application
    • B01F35/50Mixing receptacles
    • B01F35/53Mixing receptacles characterised by the configuration of the interior, e.g. baffles for facilitating the mixing of components
    • B01F35/531Mixing receptacles characterised by the configuration of the interior, e.g. baffles for facilitating the mixing of components with baffles, plates or bars on the wall or the bottom
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B28WORKING CEMENT, CLAY, OR STONE
    • B28BSHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B19/00Machines or methods for applying the material to surfaces to form a permanent layer thereon
    • B28B19/0092Machines 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
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2103/00Function or property of ingredients for mortars, concrete or artificial stone
    • C04B2103/10Accelerators; Activators
    • C04B2103/12Set accelerators
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2111/00Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/00474Uses not provided for elsewhere in C04B2111/00
    • C04B2111/00612Uses not provided for elsewhere in C04B2111/00 as one or more layers of a layered structure
    • C04B2111/0062Gypsum-paper board like materials
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2111/00Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/20Resistance against chemical, physical or biological attack
    • C04B2111/28Fire resistance, i.e. materials resistant to accidental fires or high temperatures

Definitions

  • Set gypsum which comprises calcium sulfate dihydrate
  • gypsum board employed in typical drywall construction of interior walls and ceilings of buildings.
  • gypsum-containing board is prepared by forming a mixture of calcined gypsum, that is, calcium sulfate hemihydrate and/or calcium sulfate anhydrite, and water, as well as other components, as desired.
  • the mixture typically is cast into a pre-determined shape on the surface of a conveyor or in a tray.
  • the calcined gypsum reacts with water to form a matrix of crystalline hydrated gypsum or calcium sulfate dihydrate.
  • the desired hydration of the calcined gypsum is what enables the formation of an interlocking matrix of set gypsum crystals, thereby imparting strength to the gypsum structure in the gypsum- containing product. Mild heating can be used to drive off unreacted water to yield a dry product.
  • Gypsum mixers and methods of producing gypsum products are described, for example, in U.S. Patent Nos: 1 ,767,791 ; 2,253,059; 2,346,999; 4,183,908, 5,683,635; 5,714,032; and 6,494,609.
  • Accelerator materials are commonly used in the production of gypsum products to enhance the efficiency of hydration and to control set time. Accelerators are described, for example in U.S. Patent Nos: 3,573,947; 3,947,285; 4,054,461 ; and 6,409,825.
  • Some accelerators include finely ground dry calcium sulfate dihydrate, commonly referred to as "gypsum seeds.” The gypsum seeds enhance nucleation of the set gypsum crystals, thereby increasing the crystallization rate thereof.
  • accelerators have been added to the same mixer chamber as that used to combine water with calcined gypsum.
  • accelerator While addition of accelerator to the mixer has the advantage of mixing the accelerator well and evenly throughout the water and calcined gypsum mixture, the accelerator can also cause the gypsum to begin setting prematurely. This premature setting causes the mixer to clog, can cause damage to the mixer, limits efficiency, and necessitates more frequent mixer cleaning. Mixer cleaning requires shutting down a board line with a serious detriment to productivity. Although additives including retarders have been used in the mixer to combat premature setting, such additives contribute additional costs and considerations. [0003] Conventional gypsum seed accelerator materials progressively lose their effectiveness upon aging, even under normal conditions.
  • the calcium sulfate dihydrate accelerator material with any of a number of known coating agents, such as, for example, sugars, including sucrose, dextrose and the like, starch, boric acid, or long chained fatty carboxylic acids including salts thereof.
  • a method of preparing a heat resistant accelerant slurry and introducing the slurry into a post-mixer aqueous dispersion of calcined gypsum in a discharge apparatus is provided.
  • a heat resistant accelerator (HRA) is added into a first mixing device.
  • a liquid medium is added into the first mixing device.
  • the HRA and liquid medium are mixed in the first mixing device to form the HRA slurry.
  • the aqueous dispersion of calcined gypsum is formed in a second mixing device.
  • the aqueous dispersion is discharged from the second mixing device into a discharge apparatus.
  • the HRA slurry is transferred from the first mixing device into the discharge apparatus.
  • a method for introducing a heat resistant accelerator (HRA) slurry into a post-mixer aqueous dispersion of calcined gypsum in a discharge apparatus.
  • the aqueous dispersion is discharged from the second mixing device into a discharge apparatus.
  • the HRA slurry is introduced into the discharge apparatus.
  • a system for forming a heat resistant accelerant (HRA) slurry and adding the slurry to a post-mixer aqueous dispersion of calcined gypsum is provided as an aspect of the present invention.
  • the system comprises a source of HRA; a source of liquid medium; a first mixing device; the sources operatively associated with the first mixing device; a second mixing device; a discharge apparatus operatively associated with an outlet of the second mixing device; a delivery device; the first mixing device and the discharge apparatus operatively associated with the delivery device.
  • the present invention has particular utility in the preparation of gypsum board such as wallboard or ceiling tile.
  • gypsum board such as wallboard or ceiling tile.
  • the dispersion is deposited onto a moving coversheet.
  • a second coversheet is applied to the deposited contents prior to drying.
  • a second coversheet is not employed.
  • Figure 1 shows a schematic plan view of one embodiment of a system for preparing a heat resistant accelerant slurry and adding the accelerant slurry to a post-mixer aqueous dispersion of calcined gypsum.
  • Figure 2 shows a schematic plan view of another embodiment of a system for preparing a heat resistant accelerant slurry and adding the accelerant slurry to a post-mixer aqueous dispersion of calcined gypsum.
  • Figure 3 shows a schematic cross-sectional view of one embodiment of a heat resistant slurry injection subsystem.
  • Figure 4 shows a schematic cross-sectional view of another embodiment of a heat resistant slurry injection subsystem.
  • Figure 5 shows a partial perspective view of one embodiment of a heat resistant slurry subsystem.
  • Figure 6 shows a partial perspective view of another embodiment of a heat resistant slurry subsystem.
  • Figure 7 shows a partial perspective view of still another embodiment of a heat resistant slurry subsystem.
  • Figure 8 shows a partial perspective view of a mixer and discharge apparatus.
  • the present invention is premised, at least in part, on the surprising discovery that the problems associated with use of heat resistant accelerator (HRA) can be minimized by forming a HRA slurry and then adding the slurry to an aqueous dispersion of calcined gypsum.
  • HRA heat resistant accelerator
  • the HRA slurry is added to the aqueous dispersion after it has left a stucco mixer, for example, a pin, multipass, or other conventional mixer.
  • the discharge apparatus according to the invention does not require a separate power source in order to mix the high viscosity production additive with the aqueous dispersion of calcined gypsum as the dispersion passes from the stucco mixer through the discharge apparatus.
  • Fig. 1 shows a system 12 for preparing a heat resistant accelerant (HRA) slurry and adding it to a post-mixer aqueous dispersion of calcined gypsum.
  • the system comprises a first mixing device 15 for preparing the HRA slurry, and a second mixing device 17, for example, a stucco mixer such as a pin mixer, multipass mixer, pinless mixer, or other mixer that can be used to prepare aqueous gypsum dispersions, with interior 18 for preparing the aqueous dispersion of calcined gypsum.
  • a HRA source 21 and liquid medium source 24 Operatively associated with the first mixing device 15 are a HRA source 21 and liquid medium source 24.
  • Control meters 27, 30 can be further operatively associated with the sources 21, 24, for controling the flow of HRA and liquid medium into the first mixing device 15.
  • the positioning of the control meters, 27, 30, can be varied, and can be configured in any position that allows for metering of the source materials.
  • the HRA slurry formed in the first mixing device 15 is operatively connected to a discharge apparatus 33, which is operatively associated with a mixer outlet 36, and terminating in an outlet 39.
  • the outlet comprises a boot.
  • a boot is appropriate for use on the discharge apparatus used for depositing of the main field slurry-as opposed to the densified layer slurry.
  • the outlet is provided as a conduit such as hose.
  • a conduit or hose outlet is appropriate for a densified layer discharge apparatus.
  • the first mixing device 15 can be operatively associated with the discharge device 33 via a transfer line 42, which can have a plurality of subsections, for example, 45, 48.
  • a delivery device 51 can be operatively associated with the first mixing device 15 and discharge apparatus 33 so as to permit flow of HRA slurry.
  • the delivery device 51 is a pump, for example, a positive displacement pump.
  • Appropriate pumps for use in the systems of the invention are discussed in more detail in relation to the methods of the invention.
  • the system 12 need only comprise a single discharge apparatus 33, as is shown in Fig. 1
  • the system 12 can also comprise one or more additional discharge apparatus, for example, 133, 233, operatively associated with second and third mixer outlets 136, 236, and can terminate at 139, 239.
  • the second and third discharge apparatuses, 133, 233 can be operatively associated with the first mixing device 15 with transfer lines 142 with, for example, subsections 145, 148, 242, with, for example, subsections 245, 248), and can further incorporate delivery devices 151 , 251 , in a manner analogous to that described for the operative association of the first mixing device 15 with the discharge apparatus 33.
  • the system 12 is configured so that the HRA slurry can be transferred from the first mixing device 15 to the discharge apparatus 33.
  • the discharge apparatus can comprise an injection ring 54 comprising at least one injection port 57.
  • Any additional discharge apparatuses provided in the subsystem 12, for example, 133, 233, can further comprise injection rings, for example, 154, 254, and ports, for example, 157, 257.
  • injection rings are discussed in the context of both systems and methods of the present invention, other means of injection can be employed in addition or in the alternative to an injection ring.
  • a needle on a transfer line can be used for transfer into the discharge apparatus.
  • a nipple is provided in the discharge apparatus to allow transfer into the apparatus.
  • Fig. 2 shows a system 112, which is a variation on the system 12 of Fig. 1.
  • System 112 can comprise a delivery device 51 to assist in the transfer of HRA slurry into multiple discharge apparatuses, for example, 33, 133, 233.
  • Use of the delivery device 51 as a common delivery device can be accomplished by branching the transfer line 42 using an udder, manifold, or other device with branching capability 60 that branches at 63 to provide multiple branch lines, for example, 66, 69, and 72.
  • the branches lines and/or udder, manifold, or other device with branching capability can incorporate control valves or like devices, for example, 67, 70, and 73, to control the flow of HRA slurry through the branch lines, for example, 66, 69, and 72, such valves can also or in the alternative be associated with the branching device 60.
  • These branch lines can be connected to the discharge apparatuses 33, 133, 233, via injection rings, for example, 54, 154, 254, and injection ports, 57, 157, 257, in a manner analogous to that described above for system 12. [0025] Fig.
  • FIG. 3 shows an embodiment in which the transfer line 42 comprises an udder, manifold, or other device with branching capability 75 that splits the transfer line 42 into a plurality of branch lines 78, 81 , and 84.
  • Three branch lines are shown for illustrative purposes only.
  • the injection ring 54 of Fig. 3 is shown with a plurality of injection ports 57, 57', and 57", but again that number is shown for illustrative purposes only.
  • the branch lines 78, 81 , and 84 are feed into injection ports 57, 57", and 57' respectively.
  • additional injection rings for example, 154, 254, as depicted in Fig. 1 , can also incorporate the aforementioned features. [0026] Fig.
  • FIG. 4 shows a variation on the embodiment shown in Fig. 3, which incorporates a tee 87 that allows mixing of two or more production additives prior to injection into the discharge apparatus 33.
  • the tee 87 comprises a junction 90 at which HRA slurry and a second additive converge from inlets 93, 96, respectively. While Fig. 4, only shows a tee 85 for one of the injection ports 57 that is for illustrative purposes only. Any number of the injection ports can have a tee 87 associated with them.
  • Fig. 5 shows a HRA mixing subsystem 315, which is an example of a form that the first mixing device can take.
  • the HRA mixing subsystem 315 can be incorporated into the systems, for example, 12 and 112, and utilized in the methods . of the invention.
  • the HRA mixing subsystem 315 comprises a bottom discharge tank 320.
  • the bottom discharge tank 320 comprises an interior 323 and an interior perimeter 326.
  • One or more baffles, for example, 329, 329', 329" can be arrayed about the interior perimeter 326.
  • HRA and liquid medium sources, 21 , 24, are operatively associated with the bottom mixing tank 320.
  • the HRA subsystem also can comprise an agitator 332 positioned so as to facilitate mixing of the HRA and liquid medium.
  • agitator 332 is shown as a motor/propeller type device, that is for illustrative purposes only as the agitator can take on a number of different forms provided that a particular form facilitates mixing.
  • suitable mixer/agitator devices and methods also include static mixers, spraying the liquid medium at the HRA, and a rotating cement mixer type mixer that can also comprise baffles.
  • an approximately 1750 rpm motor is used to spin the propeller for the agitator.
  • the cylindrical/frustoconical representation of the bottom discharge tank as shown in Fig. 5 is for illustrative purposes only, as it can take on a number of different shapes.
  • the bottom discharge tank 320 is operatively associated with a discharge apparatus, for example, 33, 133, and 233 as shown in Figs. 1 and 2.
  • a delivery device 51 for example, a pump, can be provided to assist in the transfer of the HRA slurry from the bottom mixing tank 320 and the discharge apparatus 33.
  • An example of such a pump is a progressive cavity pump from Moyno.
  • Fig. 6 shows an HRA eductor subsystem 415, which is an example of a form that the first mixing device can take.
  • the HRA eductor subsystem 415 is operatively associated with HRA and liquid medium sources, 21 and 24 respectively.
  • the eductor subsystem 415 comprises an eductor 450 and an entrance chamber 453.
  • the entrance chamber 453 comprises an entrance 456 to allow insertion of the HRA from the source 21.
  • the entrance chamber 453 can also include one or more inlet ports 459 for insertion of the liquid medium from the source 24 via a source line 461 and liquid medium entrance line 462.
  • the source line 461 can branch at 465 to enter the eductor 450 at 468. In the absence of the entrance line 462, a branch at 465 is not necessary.
  • a valve 471 can be incorporated into the HRA eductor subsystem 415 between the entrance chamber 453 and the eductor 450.
  • a delivery device 51 can be provided to facilitate transfer of the HRA slurry to the discharge apparatus 33. Any type of eductor can be used in the present invention. In some embodiments, an inductor is substituted for the eductor. Examples of suitable eductors and inductors are available from Fox Valve (Dover, N.J.).
  • Fig. 7 shows a HRA eductor subsystem 515, which is a variation on the subsystem 415 shown in Fig. 6.
  • the subsystem 515 can generally have the same attributes as those described for the subsystem 415.
  • the subsystem 515 comprises some additional elements.
  • a source pump 551 is operatively associated between the eductor 450 and liquid medium source 24.
  • a holding tank 574 is operatively associated between the eductor 450 and the delivery device 51. The holding tank 574 allows for positioning of the source pump 551 so the eductor will properly function based on the Venturi principle given the back pressure the HRA slurry can experience when entering the discharge apparatus 33.
  • Fig. 8 shows a discharge apparatus 633, which is one embodiment for the discharge apparatus 33, 133, 233, etc.
  • the discharge apparatus 633 also displays a number of different elements and attributes that can be shared with a discharge apparatus generally.
  • the discharge apparatus comprises a gate 680 with gate opening 682, a series of hose sections 683, 685 and 688, a cage valve 691 , and two injection rings 54, 654 with injection ports 57, 657, and an outlet 639.
  • the gate 680 acts as an adapter operatively associated with both the second mixing device and the discharge apparatus that allows the discharge apparatus' conduit to attach to the second mixing device 17 at the mixer outlet 36.
  • the gate 680 is shown with an injection port 757.
  • the injection ports 57, 657, and 757 are examples of possible locations for entry of HRA, foam, or other production additive.
  • Other additives, such as sodium trimetaphosphate and other phosphates, that can be used include those described in concurrently filed and co-owned application "METHODS OF AND SYSTEMS FOR ADDING A HIGH VISCOSITY GYPSUM ADDITIVE TO A POST- MIXER AQUEOUS DISPERSION OF CALCINED GYPSUM" (Attorney Reference
  • the hose section 685 separating the rings 54, 654 is about 15 to about 16 inches long.
  • the transfer line 42 or other transfer lines can be connected at any of the injection ports.
  • the positioning of the cage valve 691 can be varied along the length of the discharge conduit 633 and allow for control of flow in the discharge conduit.
  • the discharge apparatuses and systems of the invention can incorporate elements and subsystems as described in co-owned U.S. Patent No. 6,494,609.
  • the methods of the invention comprise the formation of a HRA slurry from HRA and a liquid medium.
  • the HRA slurry formation can also comprise additional ingredients.
  • the liquid medium generally comprises at least water. Additional ingredients can be added together with one or both of the HRA and liquid medium source streams. Additional ingredients can also be added in other streams, either alone or in combination with one another.
  • HRAs are generally known in the art, and any appropriate HRA can be utilized in the slurry formation of the present invention. Suitable HRAs and methods of producing the same are described, for example, in U.S. Patent No. 3,573,947.
  • HRA can be produced using a ball mill or other suitable grinding device by grinding calcium sulfate dihydrate in a substantially dry state. Preferrably, the calcium sulfate is ground to achieve smallest particle size while maintaining a large overall surface area, but not so small that the slurry to be formed would have undesirable properties, for example, excessive viscosity.
  • HRAs for use in the present invention are also referred to as ball mill accelerators (BMAs) and coated accelerators (CAs).
  • HRA for use in the present invention has a coating that aids in maintaining the effectiveness of the HRA when stored for extended periods of time.
  • HRA coatings can comprise without limitation one or more of the following: sugars, including sucrose, dextrose and the like, starch, boric acid, and long chain fatty acids including salts thereof.
  • a heat resistant accelerator for use in the present invention preferably has heat resistant attributes, there is no requirement that the HRA pass any type of heat resistance test.
  • HRA applicable to this invention also includes coated calcium sulfate dihydrate that has been subjected to one or more drying steps to improve the attributes of the accelerator.
  • CSA climate stabilized accelerator
  • organic phosphonates such as DEQUEST® phosphonates commercially available from Solutia, Inc., St. Louis, Missouri, are utilized.
  • DEQUEST® phosphonates include DEQUEST® 2000, DEQUEST® 2006, DEQUEST® 2016, DEQUEST® 2054, DEQUEST® 2060S, DEQUEST® 2066A, and the like.
  • addition of one or more phosphorous containing compounds such as phosphates and preferably sodium trimetaphopshate can also be employed.
  • Methods of preserving the efficacy of the HRA slurry also include the use of a gypsum solution including calcium sulfate dihydrate, and preferably a saturated calcium sulfate dihydrate solution.
  • a gypsum solution including calcium sulfate dihydrate, and preferably a saturated calcium sulfate dihydrate solution.
  • One of skill in the gypsum art will be able to identify the appropriate type of HRA for a given gypsum application based on the teachings of the present invention and the knowledge available in the art.
  • the methods of the present invention can utilize one or more systems, subsystems, and elements as described herein, for example, as described in respect to the figures. However, the methods can employ various other systems, subsystems, and elements.
  • one or more additional accelerators can be used.
  • additional accelerators include potash, wet gypsum accelerator (WGA), climate stabilized accelerator (CSA), and any accelerator known in the gypsum art.
  • WGA wet gypsum accelerator
  • CSA climate stabilized accelerator
  • the additional accelerant can be added in the aqueous dispersion of calcined gypsum mixer or outside of that mixer, that is, in the discharge apparatus.
  • potash, in granule and/or powder form is used as an additional accelerator.
  • HRA and liquid medium are introduced into the first mixing device 15 from sources 21 and 24 respectively, the rate, volume, and other parameters of which can be controlled using meters 27 and 30 respectively.
  • the introduction of the HRA and liquid medium to the first mixing device comprises separately metering of the HRA and liquid medium.
  • the addition of the HRA and liquid medium to the first mixing device is continuous.
  • a feed system and method similar to that described in U.S. Patent No. 3,262,799 is utilized.
  • a method of preparing a heat resistant accelerant slurry and introducing it into a post-mixer aqueous dispersion of calcined gypsum in a discharge apparatus comprises introducing a heat resistant accelerator (HRA) into a first mixing device; adding a liquid medium into the first mixing device; mixing the HRA and liquid medium in the first mixing device to form the HRA slurry; forming the aqueous dispersion of calcined gypsum in a second mixing device; discharging the aqueous dispersion from the second mixing device into a discharge apparatus; transferring the HRA slurry from the first mixing device into the discharge apparatus.
  • HRA heat resistant accelerator
  • the HRA and liquid medium are separately introduced into the first mixing device.
  • the liquid medium comprises water.
  • the liquid medium comprises phosphate.
  • the liquid medium comprises a gypsum solution, including calcium sulfate dihydrate, and the gypsum solution can be saturated.
  • the method of HRA slurry preparation comprises disrupting vortex formation in the first mixing device, for example, when the mixing device comprises a bottom discharge tank. The disruption can be achieved using a plurality of baffles arrayed around an interior perimeter of the first mixing device.
  • the transferring step of the method comprises pumping the HRA slurry into the discharge apparatus.
  • the pumping comprises the use of a positive displacement pump.
  • a substantial percentage of an added amount of HRA and an added amount of liquid medium is retained in the first mixing device less than less than 24 hours, less than 18 hours, less than 12 hours, less than 6 hours, less than three hours, less than two hours, less than one hour, less than 30 minutes, less than 25 minutes, less than 20 minutes, 15 minutes, less than 10 minutes, and/or less than 5 minutes.
  • the substantial percentage of the added amounts is greater than 99%, 98%, 97%, 96%, 95%, 90%, 85%, 80%, 75%, and/or 50%.
  • the time between formation of the HRA slurry and its introduction into the discharge apparatus is minimized so as to minimize the degradation of the HRA.
  • a certain percentage of the "first in” can persist in the device due to mixing or other disruption.
  • the HRA slurry is formed with a percent solids of between about 30% and about 60% percent solids. In some embodiments, the HRA slurry is formed with a percent solids of between about 40% and about 50% percent solids, which allows for the HRA slurry to be easily pumped by means of a progressive cavity pump. The higher the percent solids HRA the lower amount of slurry that needs to be pumped into the gypsum slurry to achieve the required set time at the knife.
  • This set time can vary depending on the type of gypsum rock being used by a plant, the calcination ratio of the converted gypsum dehydrate to stucco, the water stucco ratio of the slurry, the line speed/distance to the knife at a given plant, the efficiency of the HRA prior to being made into a slurry and a number of other variables particular to each plant.
  • board line speeds can vary and the distance from the knife can vary greatly
  • set times from the mixer to knife can vary as well. Therefore accelerator usage to set the board at the knife can vary over a wide range.
  • One of skill in the art will appreciate the amount of accelerator used can be tailored to individual plants and production lines on a case by case basis.
  • a method in accordance with the present invention comprises delivering a HRA slurry from a first mixing device 15 to a discharge apparatus 33 where the slurry is introduced into an aqueous dispersion of calcined gypsum that has been discharged from a second mixing device, for example, a stucco mixer such as a pin mixer, multipass mixer, pinless mixer, and other mixers that can be used to prepare gypsum dispersions, wherein the aqueous dispersion had been mixed. While gravity transfer is contemplated, the HRA slurry can be moved from the first mixing device 15 to the discharge apparatus 33 with the assistance of one or more delivery devices, for example, a pump.
  • the pump is a positive displacement pump, but other pump types can be used in addition or in the alternative can be employed, for example, a centrifugal pump.
  • suitable positive deplacement pumps include progressive cavity, gear, and peristaltic pumps.
  • the pressure of the HRA slurry in the transfer line 42 between the first mixing device 15 and discharge apparatus 33 can be measured using a pressure gauge. However, use of such a gauge is not necessary if the pump employed is self-regulating.
  • the pressure of the slurry entering the discharge apparatus should be maintained at a pressure greater than that of the contents of the discharge apparatus so as to minimize back pressure and allow efficient transfer of the HRA slurry. In some embodiments, the pressure in the discharge apparatus is between about 5 and about 15 p.s.i.
  • Pressure gauges can be incorporated into the systems and used in the methods of the present invention in a manner analogous to that described in concurrently filed and co-owned application "METHODS OF AND SYSTEMS FOR ADDING A HIGH VISCOSITY GYPSUM ADDITIVE TO A POST-MIXER AQUEOUS DISPERSION OF CALCINED GYPSUM" (Attorney Reference No. 234910), U.S.
  • the HRA slurry can be discharged into the discharge apparatus 33 through an injection port 57, which can be associated with an injection ring 54.
  • the HRA slurry is split into multiple branches to allow for multiple entries into the discharge apparatus 33. Such multiple entries can be achieved by providing multiple inlets, for example, 57, 57', and 57" in the injection ring 54.
  • the HRA slurry is combined with one or more additional additives, for example, foam, before being introduced into the aqueous dispersion of the discharge apparatus 33. Such combining can be accomplished using a tee 90 providing for entry of HRA slurry 93 and another additive 96.
  • the HRA slurry and one or more additional additives are combined approximately three inches from the point of injection into the discharge apparatus. .
  • the HRA is transferred into the discharge apparatus downstream of a pinch valve operatively associated with the discharge apparatus.
  • a dispersant is added to the discharge apparatus such as lignin, napthelene sulfate or other suitable dispersant.
  • multiple discharge apparatuses can be used. For example, if the intended product is a wallboard and top and bottom densified layers are desired, second and third discharge apparatuses, that is, densified layer extractors 133, 233 can be provided.
  • a separate delivery devices 51 , 151 , and 251 are utilized for transfer of the HRA slurry from the first mixing device 15 to the discharge apparatuses 30, 133, and 233.
  • a delivery device 51 is used for the discharge apparatus 33, and a delivery device 151 is used for the discharge apparatuses 133 and 233.
  • the HRA slurry can split into branch transfer lines using an udder, tee, manifold, or other device allowing branching of the transfer line.
  • Control of HRA slurry flow into particular branch lines can be controlled using a valve or other element of like function.
  • HRA slurry is generally introduced to the post-mixer aqueous dispersion in a stream perpendicular to the flow of the dispersion in the discharge apparatus.
  • the HRA slurry is introduced into the discharge apparatus closer or close as possible to the mixer outlet 36 than the discharge outlet 39.
  • the introduction occurs from about 2.5 inches to 3 inches from the mixer outlet 36.
  • the introduction occurs about 1 inch from the mixer outlet.
  • moving the introduction of the HRA slurry downstream in the discharge apparatus will serve to delay setting acceleration.
  • each densified layer discharge apparatus 133, 233 can comprise and/or be operatively associated with one or more of the following: a hose and a ring, for example, 154, 254.
  • the percentage of HRA slurry to provide a proper set is dependent on the amount of aqueous slurry that is being applied to the densified layer layer of the board.
  • gypsum slurry For example, if 10% of the main gypsum slurry, aqueous dispersion from the second mixing device 17, is being applied to the first, for example, bottom, densified layer, then preferably approximately 10% of the HRA is directed to the bottom densified layer through the bottom discharge apparatus 133. If a second, for example, top, densified layer is being utilized, the proportion of HRA slurry would again preferably approximately match the percentage of gypsum slurry being applied to the top densified layer. Percentages of gypsum slurry from the second mixing device 17 generally range from about 5% to about 20%.
  • top and bottom are relative terms in respect to which orientation of the gypsum product one is referring to.
  • bottom refers to a first paper, that is, cover sheet that travels beneath the gypsum mixer and the densified layer that is applied to that first paper.
  • Top refers to a second paper that is applied after addition of the gypsum slurry through the main discharge apparatus 33 to the bottom paper, as well as the densified layer applied to the second paper.
  • the first mixing device 15 comprises a bottom discharge mixing tank, and the mixing step comprises use of the mixing tank.
  • the bottom discharge mixing tank further comprises an agitator, and the mixing step can comprise agitation of the HRA and liquid medium.
  • An example of bottom discharge tank 320 is illustrated in Fig. 5 and discussed herein.
  • the method utilizes an eductor as the first mixing device, and the mixing step comprises use of the eductor. Exemplary eductor subsystems 415, 515, can be used and are illustrated in Figs. 6 and 7, respectively.
  • the HRA slurry formed is transferred initially to a holding tank 574 and then pumped with a delivery device 51 to the discharge apparatus 33.
  • a holding tank 574 for HRA slurry By using the holding tank, proper pressure is retained for the eductor 450 to operate correctly.
  • Any of the methods described herein can also involve a holding tank 574 for HRA slurry, provided that the time that the HRA slurry spends in the tank is minimized.
  • the HRA slurry is kept in the tank less than about 10 minutes.
  • the systems and method of the present invention have the benefit of delaying setting of an aqueous dispersion of calcined gypsum by delaying the introduction of HRA slurry until after the dispersion has left the stucco mixer, that is, the second mixing device, 17.
  • the methods allow for addition of less water to the stucco mixer resulting in a lower water-stucco ratio, because setting in the mixer because of absence of accelerator in the second mixing device interior 18.
  • Methods and systems are also contemplated for introducing the HRA slurry once formed directly into the second mixing device 17 instead of or in addition to introduction into the discharge apparatus.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Dispersion Chemistry (AREA)
  • Organic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Producing Shaped Articles From Materials (AREA)
  • Curing Cements, Concrete, And Artificial Stone (AREA)
  • Preparation Of Clay, And Manufacture Of Mixtures Containing Clay Or Cement (AREA)

Abstract

L’invention concerne des procédés et des systèmes destinés à préparer une boue accélératrice et résistante à la chaleur (HRA). L’invention concerne également des procédés et des systèmes pour introduire la boue HRA dans une dispersion aqueuse de gypse calciné dans un appareil d’évacuation en aval d’un mixeur de stuc dans lequel la dispersion a été préparée. Ces procédés et systèmes sont utiles dans la production de produits variés en gypse tels que des plaques, notamment des plaques murales et des dalles de plafond.
EP05741113A 2005-04-27 2005-04-27 Procedes et systemes de preparation d une boue acceleratrice resistante a la chaleur et d ajout de la boue acceleratrice a une dispersion aqueuse de gypse calcine apres l'etape de melange Withdrawn EP1874707A1 (fr)

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PCT/US2005/014512 WO2006115498A1 (fr) 2005-04-27 2005-04-27 Procedes et systemes de preparation d’une boue acceleratrice resistante a la chaleur et d’ajout de la boue acceleratrice a une dispersion aqueuse de gypse calcine apres l'etape de melange

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EP1874707A1 true EP1874707A1 (fr) 2008-01-09

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EP (1) EP1874707A1 (fr)
JP (1) JP2008539104A (fr)
CN (1) CN101189195A (fr)
AU (1) AU2005331095A1 (fr)
BR (1) BRPI0520233A2 (fr)
CA (1) CA2602041A1 (fr)
IL (1) IL186155A0 (fr)
MX (1) MX2007013365A (fr)
NO (1) NO20075072L (fr)
NZ (1) NZ561842A (fr)
WO (1) WO2006115498A1 (fr)

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FI123184B (fi) * 2011-04-20 2012-12-14 Upm Kymmene Corp Menetelmä ja laitteisto lisäaineen lisäämiseksi sementtimäiseen koostumukseen
US9821281B2 (en) * 2014-04-18 2017-11-21 United States Gypsum Company Eductor based mixer for mixing stucco and water

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Publication number Priority date Publication date Assignee Title
US2862829A (en) * 1956-07-18 1958-12-02 Nat Foam Systems Inc Manufacture of foamed gypsum and the like
US3262799A (en) * 1960-08-01 1966-07-26 United States Gypsum Co Method for making ultrafine calcium sulfate dihydrate crystals
US3573947A (en) * 1968-08-19 1971-04-06 United States Gypsum Co Accelerator for gypsum plaster
GB1389429A (en) * 1972-11-07 1975-04-03 Bpb Industries Ltd Gypsum boards
GB2281231B (en) * 1993-07-12 1997-11-19 Bpb Industries Plc A method of manufacturing multilayer plasterboard and apparatus therefor
JP3494702B2 (ja) * 1994-07-15 2004-02-09 吉野石膏株式会社 混合撹拌機及び混合撹拌方法
JP3483062B2 (ja) * 1995-04-06 2004-01-06 株式会社竹中工務店 高流動コンクリート用細骨材
ID21641A (id) * 1997-08-21 1999-07-08 United States Gypsum Co Produk yang mengandung gypsum dengan peningkatan ketahanan terhadap deformasi tetap dan metode serta komposisi untuk memproduksinya
EP1114005B1 (fr) * 1998-07-30 2005-11-16 United States Gypsum Company Produit contenant du gypse presentant une resistance accrue a la deformation permanente, et procede et composition permettant d'obtenir ce produit
US6379458B1 (en) * 2000-02-11 2002-04-30 United States Gypsum Company Efficient set accelerator for plaster
US6409824B1 (en) * 2000-04-25 2002-06-25 United States Gypsum Company Gypsum compositions with enhanced resistance to permanent deformation
US6409825B1 (en) * 2000-11-22 2002-06-25 United States Gypsum Company Wet gypsum accelerator and methods, composition, and product relating thereto
US6494609B1 (en) * 2001-07-16 2002-12-17 United States Gypsum Company Slurry mixer outlet

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Publication number Publication date
MX2007013365A (es) 2008-01-21
CN101189195A (zh) 2008-05-28
NO20075072L (no) 2007-11-23
CA2602041A1 (fr) 2006-11-02
AU2005331095A1 (en) 2006-11-02
IL186155A0 (en) 2008-01-20
NZ561842A (en) 2011-03-31
WO2006115498A1 (fr) 2006-11-02
JP2008539104A (ja) 2008-11-13
BRPI0520233A2 (pt) 2009-04-22

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