KR20080021617A - Method of and system for preparing a heat resistant accelerant slurry and adding the accelerant slurry to a post-mixer aqueous dispersion of calcined gypsum - Google Patents

Abstract

Methods and systems are provided for preparing a heat resistance accelerator (HRA) slurry. Also provided are methods and systems for introducing a HRA slurry to an aqueous dispersion of calcined gypsum in a discharge apparatus downstream of a stucco mixer in which the dispersion was prepared. These methods and systems are useful in the production of various gypsum products such as board including wallboard and ceiling tiles. ® KIPO & WIPO 2008

Description

Preparation of a thermal resistance promoter slurry and a method and system for adding the promoter slurry to an aqueous dispersant post-mixer of calcined gypsum. CALCINED GYPSUM}

Cured gypsum, including calcium sulfate dihydrate, is a well known material that is commonly included in many types of products, such as gypsum boards used in the construction of representative drywall of interior walls and ceilings of buildings. In general, such gypsum-containing boards are prepared by forming calcined gypsum, ie calcium sulfate hemihydrate and / or a mixture of calcium sulfate anhydrite and water, together with other components if necessary. . The mixture is cast into a predetermined shape, for example on the surface of the conveyor or in a tray. As the mixture moves along the conveyor belt, the calcined gypsum reacts with water to form a matrix of crystalline hydrated gypsum or calcium sulfate dihydrate. Preferred hydration of the calcined gypsum is to make the interlocking of the hardened gypsum crystal matrix, thereby giving strength to the gypsum structure in the gypsum-containing product. Mild heating may be used to remove unreacted water and to obtain a dry product. Gypsum mixers and methods for making gypsum products are described, for example, in US Pat. No. 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 to improve hydration efficiency and control the curing time in the production of gypsum products. Promoters are described, for example, in US Pat. No. 3,573,947; 3,947,285; 4,054,461; And 6,409,825. Some promoters include finely ground dry calcium sulfate dihydrate, also commonly referred to as "gypsum seed." The gypsum seed enhances nucleation of the hardened gypsum crystals, thereby increasing the rate of crystallization thereof. Traditionally, accelerators have been added to the same mixer chamber that is used to mix water and calcined gypsum. Adding an accelerator to the mixer has the advantage of allowing the accelerator to mix well, but also the accelerator may initiate early curing when gypsum. Early curing at this time can clog the mixer, cause damage to the mixer, reduce efficiency, and make the mixer clean more often. Mixer cleaning requires board line stops that can seriously damage productivity. Additives containing a coagulation retardant may be used in the mixer to prevent premature cure when such additives incur additional costs and considerations.

Conventional gypsum seed promoter materials gradually lose their effectiveness as they age, even under normal conditions. In this respect, some of the performance of the accelerators is lost even when ground, and the gypsum seeds rapidly lose their effects over time while being treated or stored. The loss of facilitation effect of conventional accelerator materials is exacerbated when the accelerator is exposed to heat and / or moisture. In order to prevent the loss of the gypsum seed over time, especially under heating conditions, calcium sulphate dihydrate promoters may be prepared, for example, containing a sugar, starch, boric acid or salts thereof such as sucrose, dextrose and the like. It is common to coat with any of many known coatings, such as chain fatty carboxylic acids. Conventional heat resistance promoter materials are ineffective when contacted with moisture, and thus are ground and provided in a dry form, for example, because the promoter particles are undesirably agglomerated and / or the coating is often dissolved in water.

The new materials and methods must overcome the above problems of heat resistance promoters while preserving the advantages of using such accelerators.

1 shows a plan view showing one embodiment of a system for preparing a heat resistance promoter slurry and adding the promoter slurry to an aqueous dispersant post-mixer of calcined gypsum.

FIG. 2 shows a plan view showing another embodiment of a system for preparing a heat resistance promoter slurry and adding the promoter slurry to an aqueous dispersant post-mixer of calcined gypsum.

3 shows a cross-sectional view of one embodiment of a heat resistant slurry injection subsystem.

4 shows a cross-sectional view showing another embodiment of a heat resistant slurry injection subsystem.

5 shows a partial perspective view of one embodiment of a heat resistant slurry sub-system.

6 shows a partial perspective view of another embodiment of a thermal resistance slurry subsystem.

7 shows a partial perspective view of another embodiment of a thermal resistance slurry subsystem.

8 shows a partial perspective view of the mixer and the discharge device.

The present invention is susceptible to various modifications and optional configurations, and their particular illustrated embodiments are shown in the drawings and are described in detail below. However, the invention is not limited to the matters described in the above embodiments, but rather all modifications, optional configurations and equivalents falling within the spirit and scope of the invention as described by the appended claims are included in the invention.

According to one aspect of the present invention there is provided a method of preparing a thermal resistance promoter slurry and feeding the slurry into an aqueous dispersant post-mixer of calcined gypsum in a discharge device. Heat resistant accelerator (HRA) is added to the first mixing device. A liquid medium is added into the first mixing device. The HRA and liquid medium are mixed in a first mixing device to produce the HRA slurry. The aqueous dispersant of the calcined gypsum is prepared in a second mixing device. The aqueous dispersant is discharged from the second mixing device to the discharge device. The HRA slurry is transferred from the first mixing device to the discharge device.

According to another aspect of the present invention, a method is provided for introducing a heat resistance promoter (HRA) slurry into an aqueous dispersant post-mixer of calcined gypsum in a discharge device. The aqueous dispersant is discharged from the second mixing device to the discharge device. The HRA slurry is introduced into the discharge device.

In one aspect of the present invention, a system is provided for preparing a thermal resistance promoting (HRA) slurry and adding the slurry into an aqueous dispersant post-mixer of calcined gypsum. The system comprises an HRA source; Liquid medium sources; A first mixing device; The sources interlocked with the first mixing device; Second mixing device; A discharge device interlocked with the outlet of the second mixing device; Delivery device; And a first mixing device and a discharge device interlocked with the delivery device.

For example, the present invention has a special use in the manufacture of gypsum boards such as wallboards or ceiling tiles. In this embodiment, the HRA slurry is added to an aqueous dispersant of calcined gypsum, and then the dispersant is precipitated on the moving coversheet. In the case of a wall board, a second cover sheet is applied to the precipitated contents before drying. In some embodiments, such as ceiling tiles, no second cover sheet is used.

The method, system and components thereof of the present invention are further described in the drawings and the detailed description of the invention, and representative embodiments are provided.

The present invention results from the surprising discovery that, at least in part, the problems associated with the use of a heat resistance promoter (HRA) can be minimized by preparing an HRA slurry and then adding the slurry to the aqueous dispersion of calcined gypsum. The HRA slurry is preferably added to the aqueous dispersion after leaving a stucco mixer, such as a pin, multipass or other conventional mixer. Since the dispersant passes from the stucco mixer through the discharge device, the discharge device according to the present invention has the advantage that no separate power source is required to mix the high viscosity production additive and the aqueous dispersant of the calcined gypsum.

In accordance with the present invention, FIG. 1 shows a system 12 for preparing a thermal resistance promoter (HRA) slurry and adding it to the calcined-gypsum aqueous dispersant post-mixer. The system has a first mixing device for producing an HRA slurry and an internal 18 for producing an aqueous dispersion of calcined gypsum, for example a pin mixer with an internal 18 for producing an aqueous dispersion of calcined gypsum. And a second mixing device 17, such as a stucco mixer, such as a multipass mixer, a pinless mixer or other mixers that can be used to make aqueous gypsum dispersants. HRA source 21 and liquid medium source 24 are associated with a first mixing device 15. The control meters 27, 30 may be further associated with sources 21, 24 to regulate the flow of HRA and liquid medium entering the first mixing device 15. The positions of the control meters 27, 30 can vary and can be placed in any position as long as the metering of the source material is permitted.

The HRA slurry produced in the first mixing device 15 is linked to the mixer outlet 36 and automatically connected to the discharge device 33 which terminates at the outlet 39. In some embodiments, the outlet comprises a boot. The boot is suitable for use in the discharge device used for the deposition of the main field slurry as opposed to the densified layer slurry. In other embodiments, the outlet can be provided in a tubing such as a hose. The pipe or hose outlet is suitable as a densified bed discharge device.

The first mixing device 15 may be linked with the discharge device 33 via a transfer line 42 which may have many subsections, for example 45, 48. The delivery device 51 may be associated with the first mixing device 15 and the discharge device 33 to allow the flow of the HRA slurry. In some embodiments, the delivery device 51 is a pump, for example a positive displacement pump. Pumps suitable for use in the system of the invention are described in more detail in connection with the method of the invention. The system 12 needs to include only one discharge device 33 as shown in FIG. 1, while at the same time the system 12 is also interlocked with the second and third mixer outlets 136, 236 and terminated at 139, 239. It may also include one or more additional discharge devices such as, for example, 133, 233. The second and third discharge devices 133, 233 are interlocked with the first mixing device 15 with a transfer line 142 having, for example, subsections 145, 148, 242 (for example with subclasses 245, 248). In a manner similar to that described for the interlocking of the discharge device 33 and the first mixing device 15, the delivery devices 151, 251 may be further incorporated.

As described above, the system 12 is arranged to transfer the HRA slurry from the first mixing device 15 to the discharge device 33. The evacuation device may comprise an insertion ring 54 comprising at least one insertion port 57. Any additional evacuation device provided in subsystem 12, for example 133, 233, may further include insertion rings such as 154, 254, and ports such as 157, 257, for example. A more detailed discussion of the insertion ring 54, insertion port 57 and associated components is described below in connection with FIGS. 3 and 4. Insert rings are described in the context of both systems and methods of the present invention, and other means of insertion may be used in addition or alternatively to the insert rings. For example, in some embodiments a needle may be used on the transfer line for transfer to the discharge device. In some embodiments, nipples are provided within the discharge device to allow movement to the discharge device.

FIG. 2 shows a system 112, which is a variation of system 12 of FIG. 1. System 112 may include delivery device 51 to assist in transporting the HRA slurry into a plurality of discharge devices, such as 33, 133, 233. The use of delivery device 51 as a general delivery device is a branching capability that provides multiple branch lines, for example 66, 69 and 72, branching out of the euder, manifold or 63. 60) can be achieved by branching the transfer line 42 using another device having 60). The branch lines and / or other devices having a Euder, manifold or branching function may be used to control the flow of HRA slurry through the branch lines, eg 66, 69 and 72. It is possible to incorporate a valve or similar devices, for example 67, 70 and 73, which valves may also be selectively associated with the branch device 60. These branch lines can be connected to the outlet devices 33, 133, 233 by insertion rings, for example 54, 154, 254 and insertion ports 57, 157, 257, in a manner similar to that described in system 12. .

FIG. 3 shows one embodiment where the transfer line 42 comprises a juder, a manifold or another engine having branching function 75 separating the transfer line 42 into a plurality of branch lines 78, 81 and 84. Three branch lines are shown for illustrative purposes only. The insertion ring 54 of FIG. 3 is shown with a plurality of insertion ports 57, 57 'and 57 ", but the number is also only for illustrative purposes. Branch lines 78, 81 and 84 are each insertion ports Supplied into 57, 57 "and 57 '. In some implementations, additional insertion rings, for example additional insertion rings such as 154 and 254 as shown in FIG. 1, can be incorporated into the aforementioned feature.

FIG. 4 shows a variant of the embodiment shown in FIG. 3, which includes a T tube 87 which allows mixing of two or more product additives before being injected into the evacuation device 33. The T tube 87 includes a connection 90 where the HRA slurry and the second additive collect from inlets 93, 96, respectively. 4 shows the T-tube 85 in only one of the insertion ports 57, but this is for illustration only. Any number of insertion ports can have a T-tube 87 connected to it.

5 shows the HRA mixing subsystem 315, which is an example of the form that the first mixing device may take. The HRA mixing subsystem 315 can be incorporated into systems such as 12 and 112, for example, and can be used in the methods of the present invention. The HRA mixing subsystem 315 includes a bottom discharge tank 320. The bottom discharge tank 320 includes an interior 323 and an interior perimeter 326. One or more baffles, for example 329, 329 ', 329 ", may be arranged around the inner boundary 326. HRA and liquid medium sources 21, 24 are associated with the bottom mixing tank 320. The HRA The subsystem may also include an agitator 332 that is placed to facilitate mixing of the HRA and the liquid medium. The agitator 332 has been shown as a motor / propeller type device, but for illustrative purposes, the agitator may be used for mixing. Many other forms may be taken to provide specific forms that facilitate: Examples of suitable mixer / stirrer devices and methods also include a rotating cement, which may include a static mixer and baffle to spray the liquid medium to the HRA. A rotating cement mixer type mixer is included In some embodiments, about 1750 rpm motor is used to rotate the propeller of the stirrer. The bottom discharge device in the form of a cylindrical / frustoconial as shown in figure 5 is for illustrative purposes and may take many different forms: The bottom discharge tank 320 may be a discharge device, for example FIGS. 1 and 2. It is associated with 33, 133 and 233 as shown in. To assist in transporting the HRA slurry from the bottom mixing tank 320 and the evacuation device 33, a delivery device 51, for example a pump, may be provided. An example is a progressive cavity pump manufactured by Moyno.

 6 shows the HRA eductor subsystem 415, which is an example of the form that the first mixing device may take. The HRA eductor subsystem 415 is associated with HRA and liquid medium sources 21 and 24, respectively. The eductor subsystem 415 includes an eductor 450 and an inlet chamber 453. The inlet chamber 453 includes an inlet 456 allowing HRA to be introduced from the source 21. The inlet chamber 453 also includes one or more inlet ports 459 to allow the liquid medium to flow from source 24 through source line 461 and liquid medium inlet line 462. In addition or alternatively to the liquid medium entering inlet chamber 453 through inlet port 459, source line 461 is branched at 465 and enters eductor 450 at 468. Without inlet line 462, no branch at 465 is necessary. Valve 471 may be incorporated into HRA eductor subsystem 415 between inlet chamber 453 and eductor 450. A delivery device 51 may be provided to facilitate the transfer of the HRA slurry to the discharge device 33. Any form of eductor may be used in the present invention. In some implementations, an inductor can replace the inductor. Suitable eductors and inductors are available from Fox Valve (Dover, N. J).

FIG. 7 shows the HRA eductor subsystem 515, which is a variation of subsystem 415 shown in FIG. 6. The subsystem 515 generally has the same characteristics as those described in subsystem 415. The subsystem 515 includes some additional components. Source pump 551 is interlocked between eductor 450 and liquid medium source 24. The storage tank 574 is interlocked between the eductor 450 and the delivery device 51. The storage tank 574 takes into account the location of the source pump 551, so that the eductor will perform an appropriate function based on the Venturi principle given the back pressure that the HRA slurry can experience when the discharge device 33 is introduced. .

8 shows the discharging device 633, which is another embodiment of the discharging device 33, 133, 233. The discharge device 633 also exhibits many other components and properties that are generally shared with the discharge device. The discharge device comprises a gate 680 with a gate opening 682, a series of hose parts 683, 685 and 688, two insertion rings 54, 654 and an outlet 639 having a cage valve 691 and insertion ports 57, 657. The gate 680 acts as an adapter to cooperate with both the second mixing device and the discharge device having a piping of the discharge device attached to the second mixing device 17 at the mixer outlet 36. Gate 680 appears with insertion port 757. The insertion ports 57, 657 and 757 are examples of places where the introduction of HRA, foam or other product additives is possible. Other additives, such as sodium trimetaphosphate and other phosphates that may be used, are submitted simultaneously with the present invention and co-owned US Application No .----------- Included in "Method of Addition to Dispersant Post-Mixer" (Agent File No. 234910). The rings 54, 654 and gate 680 may be arranged to have a plurality of insertion ports, for example, as shown in FIGS. 3 and 4. In some embodiments, the hose portion 685 away from the rings 54, 654 has a length of about 15 to about 16 inches. The transfer line 42 or other transfer line can be connected to any insertion port. The position of the cage valve 691 may vary depending on the length of the discharge pipe 633, taking into account the control of the flow in the discharge pipe. The discharge device and system of the present invention may incorporate components and subsystems as described in co-owned US Pat. No. 6,494,609.

The process of the present invention involves forming an HRA slurry from HRA and a liquid medium. The HRA slurry formation may also include additional components. The liquid medium generally comprises at least water. Additional components may be added with one or both of the HRA and the liquid medium feed stream. Additional components may also be added to other streams, each of which may be added alone or in combination with each other.

HRAs are generally known in the art and any suitable HRA may be used to prepare the slurry of the present invention. Suitable HRAs and their preparation are described, for example, in US Pat. No. 3,573,947. HRA can be prepared by grinding calcium sulfate dihydrate in a substantially dry state using a ball mill or other suitable grinding device. The calcium sulfate is preferably pulverized so that the entire surface area can be reached while at the same time reaching the smallest particle size, but not so small that the prepared slurry has undesirable properties, for example excessive viscosity. The HRAs used in the present invention are also called ball mill accelerators (BMAs) and coated accelerators (CAs). The HRA used in the present invention has a coating that helps maintain the efficacy of the HRA when stored for long periods of time. The HRA coating can include one or more of the following without limitation: long chain fatty acids including sugars, starch, boric acid and salts thereof such as sucrose, dextrose and the like. The heat resistance promoter used in the present invention preferably has heat resistance properties, but the HRA does not have to pass any kind of heat resistance test. HRA applied to the present invention also includes coated calcium sulfate dihydrate that has undergone one or more drying steps to enhance the properties of the promoter. One such accelerator is the climate stabilized accelerator (CSA). Since aqueous solutions speed up the decomposition of HRA, additives can be added to the HRA slurry to help overcome this problem. In some embodiments, organic phosphonates are used, such as DEQUEST® phosphonates, available from Solutia, Inc. of St. Louis, Missouri. Examples of such DEQUEST® phosphonates include DEQUEST®2000, DEQUEST®2006, DEQUEST®2016, DEQUEST®2054, DEQUEST®2060S, DEQUEST®2066A, and the like. In some embodiments it is also possible to add one or more phosphorus containing compounds such as, for example, phosphates and preferably sodium trimetaphosphate. Methods of preserving the effects of HRA slurries also include the use of gypsum solutions comprising calcium sulfate dihydrate and preferably saturated calcium sulfate dihydrate solution. One skilled in the gypsum art will be able to select the type of HRA suitable for a given gypsum application based on the teachings of the present invention and the knowledge available in the art.

The method of the present invention may use one or more systems, subsystems and components described herein, for example in connection with the figures. However, the method may employ various other systems, subsystems, and components. Although the method has been described in connection with such systems, subsystems and components, such description is provided to assist in a thorough understanding of the present invention and does not limit the invention as set forth in the appended claims. One or more additional promoters may also be used. Examples of such accelerators include potash, wet gypsum accelerator (WGA), climate stabilized accelerator (CSA), and other accelerators known in the gypsum art. In such embodiments where one or more additional accelerators are used, the additional promoters may be added either inside the aqueous dispersion mixer mixer of calcined gypsum or outside of the mixer, ie within the discharge device. In some embodiments, potash in particulate form and / or powder form may be used as additional promoter.

According to one aspect of the invention the HRA and the liquid medium are fed into the first mixing device 15 from sources 21 and 24, respectively, and the speed, volume and other parameters can be adjusted using meters 27 and 30 respectively. In some embodiments, introducing the HRA and the liquid medium into the first mixing device comprises separately metering the HRA and the liquid medium. In some embodiments, the addition of the HRA and the liquid medium to the first mixing device is continuous. In some embodiments, supply systems and methods similar to those described in US Pat. No. 3,262,799 are used. A method of preparing a heat resistance promoting slurry according to the present invention and feeding it to an aqueous dispersant post-mixer of calcined gypsum in a discharge device comprises: introducing a heat resistance promoter (HRA) into a first mixing device; Adding a liquid medium to the first mixing device; Mixing the HRA and liquid medium in a first mixing device to form an HRA slurry; Forming an aqueous dispersant of calcined gypsum in a second mixing device; Discharging said aqueous dispersant from a second mixing device to a discharge device; Transferring the HRA slurry from a first mixing device to a discharge device. In some embodiments, the HRA and the liquid medium are separately put into the first mixing device. In some embodiments, the liquid medium comprises water. In some embodiments the liquid medium comprises phosphate. In some embodiments the liquid medium comprises a gypsum solution comprising calcium sulfate dihydrate, the gypsum solution may be saturated.

In some embodiments the HRA slurry production method comprises disrupting vortex formation in a first mixing device, for example when the mixing device comprises a bottom discharge tank. The disruption can be accomplished using a plurality of baffles arranged around the inner boundary of the first mixing device.

In some embodiments, the transferring step of the method includes pumping the HRA slurry into the discharge device. In some embodiments, the pumping includes the use of a positive displacement pump.

In some embodiments, a significant percentage of the amount of HRA added and liquid medium added is less than 24 hours, less than 18 hours, less than 12 hours, less than 6 hours, less than 3 hours, less than 2 hours, 1 in the first mixing device. Less than hour, less than 30 minutes, less than 25 minutes, less than 20 minutes, less than 15 minutes, less than 10 minutes and / or less than 5 minutes. In some embodiments, the substantial percentage of the added amount is greater than 99%, 98%, 97%, 96%, 95%, 90%, 85%, 80%, 75% and / or 50%. In general, the time between HRA slurry formation and introduction into the discharge device is minimized to minimize degradation of the HRA. Those skilled in the art will understand that even in a device of the first type that enters first, such as a bottom discharge tank, a certain percentage of “first entered” by mixing or other milling can be maintained in the device.

In some embodiments the HRA slurry is prepared to have a solids content between about 30% and about 60%. In some embodiments the HRA slurry is prepared to have a solids content between about 40% and 50%, which allows the HRA slurry to be easily pumped by a progressive cavity pump. The higher the solids percentage, the smaller the amount of slurry that needs to be pumped into the gypsum slurry to reach the curing time required for the knife. These curing times are based on the type of gypsum rock used in the plant, the calcination rate of gypsum dehydrate converted to stucco, the water stucco rate of the slurry, and the line speed / distance from the given plant to the knife. This depends on the efficiency of the HRA before it is made into a slurry and on many other variables unique to each plant. Because the board line speeds vary greatly and the distance from the knife varies, the curing time from the mixer to the knife can also vary. The use of accelerators to cure boards in knives thus varies widely. It is believed that one of ordinary skill in the art will be able to adjust the amount of promoter used to the individual plant and production line on a case by case basis.

The method according to the invention comprises the step of delivering the HRA slurry to a discharge device in a first mixing device 15, wherein the slurry is a second mixing device, for example a fin mixer, a multipath mixer, in which an aqueous dispersion is mixed. And into the aqueous dispersion of calcined gypsum discharged from a stutter mixer, such as a pinless mixer and other mixers capable of producing gypsum dispersants. Once the weight transport is complete, the HRA slurry can be transferred from the first mixing device 15 to the discharge device with the aid of one or more delivery devices, for example a pump. In some embodiments, the pump is a volumetric pump, but other types of pumps, such as centrifugal pumps, may additionally or alternatively be used. Examples of suitable volumetric pumps include progressive cavities, gears, and peristaltic pumps. The pressure of the HRA slurry in the transfer line 42 between the first mixing device 15 and the discharge device 33 can be measured using a pressure gauge. However, if the pump is self-regulating, the use of such a gauge is not necessary. In order to minimize back pressure and to efficiently transport the HRA slurry, the pressure of the slurry entering the discharge device must be maintained above the pressure of the contents of the discharge device. In some embodiments the pressure in the discharge device is between about 5 and about 15 p.s.i. Pressure gauges can be incorporated into the system and submitted concurrently with the present application and co-owned US application No. ~~~~~~~~~~~~ "calcined high viscosity gypsum additives after aqueous dispersion of gypsum- It can be used in the method of the present invention in a similar manner as described in "Methods and Systems for Addition to the Mixer. The HRA slurry can be discharged into the discharge device 33 through an insertion port 57 that can be connected with the insertion ring 54. In some embodiments, the HRA slurry is split into several branches to allow multiple entries into the discharge device 33. This multiple inlet can be achieved by providing a plurality of inlets, for example 57, 57 'and 57 ", in the insertion ring 54. In some embodiments, the HRA slurry is introduced into the aqueous dispersion of the discharge device 33, It may be mixed with one or more additional additives, for example foams, such mixing may be achieved using a T tube 90 which provides an inflow of HRA slurry 93 and another additive 96. In some embodiments the HRA The slurry and one or more additional additives are mixed about 3 inches from the point of insertion into the evacuation device In some embodiments, the HRA is conveyed into the evacuation device downstream of a pinch valve in conjunction with the evacuation device. In some embodiments, a dispersant such as lignin, naphtelene sulfate, or other suitable dispersants may be added to the discharge device. have.

For certain gypsum products multiple discharge devices can be used. For example, if the desired product is a wall board and a top and bottom densification layer is required, a second and third discharge device, i.e., densified layer extractors 133, 233, may be provided. Only a single densification layer applies to certain wall board products as well as other board products such as ceiling tiles (see co-owned and co-pending US patent application 10 / 804,359). In some embodiments, separate delivery devices 51, 151 and 251 are used to transfer the HRA slurry from the first mixing device 15 to the discharge devices 30, 133 and 233. In another embodiment, there is a single delivery device 30 that transfers the HRA slurry to all three discharge devices. In another embodiment, the delivery device 51 is used for the discharge device 33 and the delivery device 151 is used for the discharge devices 133 and 233. Regardless of the number and the number of delivery devices, the HRA slurry is dispensed into branched transfer lines using Euder, T-tubes, manifolds or other devices that branch the transfer line. The regulation of the HRA slurry flow into a particular branched line can be controlled using a valve or other component of similar function.

The HRA slurry is generally introduced into the water based propellant post-mixer in vapor form perpendicular to the dispersant flow in the discharge device. However, addition of HRA slurries in other directions is also possible. In order to be ideally incorporated into the aqueous dispersant, the HRA slurry is introduced into the discharge device closer to or as close as possible to the mixer outlet 36 rather than outlet 39. In some embodiments the input occurs from about 2.5 inches to about 3 inches from mixer outlet 36. In some embodiments, the input occurs about 1 inch from the mixer outlet. In general, moving the HRA slurry input downstream in the discharge device will help to reduce hardening promotion.

When using the method to make a wall board product having a first, for example bottom and a second, for example top densification layer, each densification layer discharge device 133, 233 is one of: And / or may be interlocked: hoses and rings, for example 154, 254. The percentage of HRA slurry to provide adequate curing depends on the amount of aqueous slurry applied to the densifying layer of the board. . For example, if 10% of the main gypsum slurry, i.e., the aqueous dispersion from the second mixing device 17, was applied to the first, for example bottom, densified layer, then approximately 10% of the HRA was applied to the bottom discharge device 133. It is preferable to go through the bottom to the densification layer. If a second, for example, top densified layer is used, the proportion of the HRA slurry is also preferably approximately equal to the percentage of gypsum slurry applied to the top densified layer. The percentage of gypsum slurry from the second mixing device 17 generally ranges from about 5% to about 20%. As with the face and back and other corresponding terms, the terms top and bottom are relative terms related to the orientation of the gypsum product it represents. For illustrative purposes only, the bottom means a cover sheet that moves under a first paper, ie the gypsum mixer and the densification layer applied to the first paper. The top refers to the second paper applied after the gypsum slurry is added to the lower surface paper through the main discharge device 33, similarly to the densification layer applied to the second paper.

In some embodiments, the first mixing device 15 comprises a bottom discharge mixing tank, and the mixing step includes the use of a mixing tank. In this embodiment the bottom discharge mixing tank further comprises a stirrer and the mixing step may comprise stirring HRA and liquid medium. An example of a bottom discharge tank 320 is shown in FIG. 5 and described herein.

In some embodiments, the method uses an eductor as the first mixing device, and the mixing step includes the use of the eductor. Exemplary eductor subsystems 415 and 515 are shown in FIGS. 6 and 7, respectively. When using the pump as the delivery device 551 upstream of the eductor 450 and the eductor in the process, the prepared HRA slurry is first transferred to the storage tank 574 and then pumped to the discharge device 33 by the delivery device 51. By using a storage tank, an appropriate pressure is maintained for the eductor 450 to work properly. Any method described herein can include a storage tank 574 for the HRA slurry, provided that the time for which the HRA slurry is spent in the tank is minimized. In some embodiments, the HRA slurry stays in the tank for less than about 10 minutes.

The system and method of the present invention have the effect of delaying the curing of the aqueous dispersant of calcined gypsum by delaying the introduction of the HRA slurry until the dispersant leaves the stucco mixer, ie the second mixing device 17. In some embodiments, the method adds little water to the stucco mixer such that a low water-stucco ratio results from curing inside the mixer due to the absence of accelerators within the second mixing device 18. The methods and systems may also contemplate introducing the HRA slurry once produced directly into the second mixing apparatus 17 instead of or in addition to introducing it into the discharge apparatus.

All references disclosed herein, including publications, patent applications, and patents, are incorporated by reference into the present invention to the extent that they are individually and in particular incorporated by reference and to the extent described in the present invention as a whole.

The terms "a" and "an" and "the" and the like, as used in the context of the present specification, in particular in the context of the following claims, and the like, are not otherwise indicated or are clearly negated by the context. Unless otherwise, it is to be construed to include both the singular and the plural. The terms "comprising", "having" and "comprising" should be interpreted to mean without limitation, that is to say, "including, but not limited to" unless stated otherwise. In the present invention, the recitation of the range of values is used in such a way as to simplify the individual reference to each individual value within the range unless otherwise indicated, each individual value being individually It is included in the detailed description as described. All methods described in the present invention may be carried out in any suitable order unless otherwise stated in the present invention, or unless clearly contradicted by context. The use of any or all examples or exemplary languages, such as "such as" used in the present invention, is merely for better expression and does not impose a limitation on the scope of the present invention unless claimed. No word in this specification should be construed as referring to a component that is not claimed as essential to the practice of the invention.

In practicing the invention, preferred embodiments of the invention are described herein, including the most preferred forms known to the inventors. By reading the above specification, one skilled in the art can find out variations of this preferred embodiment. The inventors believe that those skilled in the art will be able to employ such variations as appropriate, and the inventors intend to practice the invention other than as specifically described herein. Thus, the invention includes all modifications and equivalents of the subject matter described in the claims appended hereto, as permitted by applicable law. Also, unless otherwise indicated or clearly contradicted by context, the present invention includes any combination of the above-described components in all possible variations thereof.

Claims (52)

Introducing a heat resistance promoter (HRA) into the first mixing device; Adding a liquid medium into the first mixing device; Mixing the HRA and a liquid medium in the first mixing device to form an HRA slurry; Forming an aqueous dispersant of calcined gypsum in a second mixing device; Discharging the aqueous dispersant from the second mixing device to a discharge device; Transferring said HRA slurry from said first mixing device to said discharging device and introducing said slurry into an aqueous dispersant after-mixer of calcined gypsum in said discharging device. The method of claim 1, Wherein the HRA and the liquid medium are each introduced into the first mixing device. The method of claim 1, The liquid medium comprises water. The method of claim 1, The liquid medium comprises phosphate. The method of claim 1, The liquid medium comprises a calcium sulfate dihydrate solution. The method of claim 5, Wherein said calcium sulfate dihydrate solution is saturated. The method of claim 1, The method further comprises milling the vortex formation in the first mixing device. The method of claim 7, wherein Said grinding is performed using a plurality of baffles disposed around an inner boundary of the first mixing device. The method of claim 1, The transferring step includes pumping the HRA slurry into a discharge device. The method of claim 9, Said pumping step comprises the use of a positive displacement pump. The method of claim 1, Introducing the HRA and liquid medium to the first mixing device comprises metering the HRA and liquid medium, respectively. The method of claim 1, Introducing the HRA and liquid medium to the first mixing device is continuous. The method of claim 1, A substantial percentage of the amount of HRA and the amount of liquid medium added is maintained in the first mixing device for less than 15 minutes. The method of claim 1, A substantial percentage of the amount of HRA and the amount of liquid medium added is maintained in the first mixing device for less than 10 minutes. The method of claim 1, A substantial percentage of the amount of HRA and the amount of liquid medium added is maintained in the first mixing device for less than 5 minutes. The method of claim 14, Said substantial percentage is greater than 99%. The method of claim 14, Said substantial percentage is greater than 95%. The method of claim 14, Said substantial percentage is greater than 90%. The method of claim 14, Said substantial percentage is greater than 75%. The method of claim 1, The method further comprises discharging the aqueous dispersant into a second discharge device. The method of claim 1, Characterized in that the foam is mixed before the HRA slurry enters the discharge device. The method of claim 1, The conveying step includes pumping with a plurality of pumps, wherein there is a pump for each discharge device that pumps the HRA slurry to each discharge device. The method of claim 1, The transferring step distributes the HRA slurry to multiple discharge apparatuses using at least one device selected from the group consisting of an udder, a manifold, a tee, a valve and a hose. How to do. The method of claim 1, Wherein the percent solids of the HRA slurry is formed between about 30% and about 60%. The method of claim 1, The percent solids of the HRA slurry is formed between about 40% and about 50%. The method of claim 1, The first mixing device comprises a bottom discharge mixing tank, The mixing step includes using the mixing tank. The method of claim 26, The bottom discharge mixing tank further comprises an agitator, Said mixing step comprises stirring said HRA and liquid medium. The method of claim 1, The first mixing device comprises an eductor, Said mixing step comprises the use of an eductor. The method of claim 28, The conveying step includes conveying the HRA slurry to a holding tank prior to conveying the HRA slurry to a discharge device. The method of claim 1, The HRA is introduced substantially perpendicular to the discharge device. The method of claim 1, Discharging the contents of said dispensing device onto a moving cover sheet. The method of claim 31, wherein And applying a second cover sheet over the discharged contents. 33. The method of claim 32, further comprising drying the sheet and precipitated contents. Discharging the aqueous dispersant from the second mixing device to the discharge device; Introducing a HRA slurry into an aqueous dispersant post-mixer of calcined gypsum in the discharge apparatus, the method comprising introducing the HRA slurry into the discharge apparatus. Source of HRA; Source of liquid medium; A first mixing device; The sources in association with a first mixing device; Second mixing device; A discharge device interlocked with the outlet of the second mixing device; Delivery device; A system for preparing a thermal resistance promoter (HRA) slurry comprising the first mixing device and the discharge device in conjunction with the delivery device and adding the slurry to an aqueous dispersant post-mixer of calcined gypsum. 36. The method of claim 35 wherein The system further comprises first and second meters for regulating the input of HRA and liquid medium to the first mixing device, respectively. 36. The method of claim 35 wherein And a plurality of baffles disposed around the inner boundary of the first mixing device. 36. The method of claim 35 wherein The delivery device includes a pump. The system of claim 38, wherein the pump comprises a positive displacement pump. 36. The method of claim 35 wherein And the delivery device is interlocked between the first mixing device and the discharge device. 36. The method of claim 35 wherein And the first mixing device is interlocked between the delivery device and the discharge device. 36. The method of claim 35 wherein The system further comprises a storage tank interlocked between the first mixing device and the discharge device. 36. The method of claim 35 wherein And a second discharge device interlocked with the second outlet of the second mixing device. The method of claim 43, And a second pump interlocked with the first mixing device and the second discharge device. The method of claim 43, And a subsystem comprising at least one member selected from the group consisting of a euder, a manifold, a tee, a valve and a hose. 36. The method of claim 35 wherein The discharge device includes a ring having a plurality of inlet ports, the ports interlocked with the delivery device. 36. The method of claim 35 wherein The discharge device includes a ring having a plurality of inlet ports, the ports interlocked with the pump. 36. The method of claim 35 wherein The system comprises a transfer line in cooperation with the discharge device and the first mixing device, the transfer line interlocked with the discharge device through a needle inserted in the discharge device. The method of claim 47, The system includes a transfer line and a yuder or manifold, Said delivery device, transfer line, eder or manifold and ring interlocked such that WGA is delivered to a plurality of inlet ports. 36. The method of claim 35 wherein And a T tube arranged to mix the HRA slurry and the foaming solution prior to introduction into the evacuation device. 36. The method of claim 35 wherein The system further comprises a pressure gauge interlocked with the transfer line, the transfer line interlocked with the discharge device. The method of claim 43, The system includes a pressure gauge associated with the transfer line, The transfer line is in communication with a second discharge device.