Mixing device

Abstract

Lightweight building panels such as plasterboard (e.g., gypsum board) are commonly used to form interior partitions in buildings. Sheets of plasterboard are typically transported and positioned by hand. Therefore, it is desirable to reduce the weight of the plasterboard. It is known to include aqueous foam in the stucco slurry used to manufacture plasterboard. However, conventional known mixers have been found to destroy the foam. The present invention provides a stucco slurry mixing apparatus 100 including an inlet 130 for introducing foam into a mixing chamber 110, the inlet 130 including an inlet opening 132 in a wall of the mixing chamber 110 and an inlet conduit 134 extending therefrom, wherein a relative angle between a longitudinal axis 136 of the inlet conduit 134 and a tangent 140 to a mixing path 124 defined by the mixing element 120 is less than 90 degrees.

Description

[Technical Field]

[0001] The present invention relates to a slurry mixing apparatus, and more particularly to a stucco slurry mixing apparatus that provides a more desirable stucco slurry. [Background technology]

[0002] Lightweight building panels such as plasterboard (e.g., gypsum board) are commonly used to form interior partitions in buildings. To form a partition, a framework is typically first constructed of wood, metal, or another suitable material, and sheets of plasterboard are attached to the frame with screws or other fasteners to form a continuous partition surface. It is also known to attach the panels to solid walls, such as brick walls, to form a more desirable finished surface. The panels are typically used to construct walls and ceilings. Plasterboard is typically formed from a stucco slurry. The stucco and other additives are typically mixed with water to form a slurry, which is then dried at high temperatures to form the plasterboard.

[0003] Sheets of plasterboard are typically transported and positioned by hand. Therefore, it is desirable to reduce the weight of the plasterboard. Furthermore, a lighter board requires a less robust supporting framework, improving assembly and reducing costs. It is known to include aqueous foam in the slurry used to form plasterboard sheets. The foam contains air bubbles, and as the plasterboard sheet is formed, the air bubbles form microvoids in the finished plasterboard sheet, resulting in a reduction in the weight of the plasterboard sheet. Summary of the Invention [Problem to be solved by the invention]

[0004] The mixing action of conventional known mixing equipment has been found to destroy the air bubbles. Furthermore, many known raw materials used in the manufacture of plasterboard are hydrophobic, and these raw materials can destroy the air bubbles on contact. To overcome these problems, it has been known to create a larger amount of foam. However, this results in an unnecessarily high proportion of foaming agent or surfactant in the slurry.

[0005] It is also known to mix less slurry to reduce cell collapse, but this has been found to result in an inhomogeneous stucco slurry and therefore a non-continuous plasterboard.

[0006] Objects and aspects of the present invention are directed to alleviating at least these problems associated with prior known mixing devices. [Means for solving the problem]

[0007] According to a first aspect of the present invention, a container for receiving and mixing the raw materials; a mixing element configured to move within the vessel and mix ingredients contained within the vessel, the movement of the mixing element defining a non-linear mixing path; A stucco slurry mixing apparatus comprising: The container is a first inlet for introducing raw materials, including at least an aqueous foam, into the vessel, the first inlet comprising an inlet opening in a wall of the vessel and an inlet conduit extending therefrom, the relative angle between a longitudinal axis of the inlet conduit and a tangent to the mixing path being less than 90 degrees; a second inlet comprising a second inlet opening in the wall of the vessel for the introduction of another raw material into the vessel; outlet for mixed slurry and Equipped with A stucco slurry mixing apparatus is provided in which the first inlet and outlet are positioned such that, during use, the average residence time of the aqueous foam within the vessel is similar to the average residence time of the other components of the stucco slurry within the vessel.

[0008] In this way, a stucco slurry mixing device is provided that helps ensure that the materials entering the device through the first inlet are dispersed into a thoroughly homogenized stucco slurry. Because the aqueous foam is supplied through the first inlet, the collapse of air bubbles within the foam can be reduced, thereby reducing the amount of foaming agent or surfactant required to achieve the desired level of aeration in the final plasterboard product. This maximizes foaming efficiency. Furthermore, the level of foaming agent or surfactant is minimized.

[0009] The inlet conduit may extend from the inlet opening in a direction away from the direction of rotation of the mixing element. In this manner, the foam traveling along the inlet conduit may have a direction of movement that at least partially coincides with the direction of movement of the stucco slurry being mixed in the vessel adjacent the first inlet. The inlet opening may be an opening in the wall of the vessel. The inlet conduit may comprise a pipe, a tube, and / or any other structure suitable for conveying aqueous foam. The inlet conduit may be linear. The inlet conduit may be straight. Alternatively, the inlet conduit may be curved. The inlet conduit may include a straight portion immediately adjacent the inlet opening and a curved portion extending from the straight portion. In this manner, the overall volume and / or footprint of the mixing device may be reduced while still providing a straight inlet conduit portion adjacent the inlet opening.

[0010] In some embodiments of the present invention, aqueous foam is supplied through a first inlet at a velocity that matches the velocity of the stucco slurry being mixed in a vessel adjacent to the first inlet, thereby reducing shear forces on the foam. Furthermore, the foam can be dispersed almost instantly within the well-homogenized stucco slurry being mixed in the vessel, thereby reducing the required mixing time. Thus, the present invention can provide a more desirable stucco slurry.

[0011] The mixing path may lie entirely within a single plane. Thus, the mixing element may have only a single direction of movement, such as rotation about a single axis. The longitudinal axis of the inlet conduit may be parallel to and spaced apart from the plane in which the mixing path lies. In this way, raw materials such as foam introduced through the first inlet may not be directed directly toward the mixing element. Such an arrangement may prevent the foam from being impacted and destroyed by the mixing element before being incorporated into the stucco slurry.

[0012] The mixing element may be positioned between the first inlet and the outlet, such that raw materials, such as foam, introduced through the first inlet may need to pass through and / or over the mixing element before being removed from the vessel through the outlet. In this manner, the stucco slurry may be homogenized. Alternatively, the first inlet may be positioned between the mixing element and the outlet, such that the aqueous foam introduced into the vessel through the first outlet does not come into direct contact with the mixing element.

[0013] The mixing element may be positioned between the second inlet and the outlet, such that other raw materials introduced through the second inlet may need to pass through or over the mixing element before being removed from the vessel through the outlet, thus homogenizing the stucco slurry. Alternatively, the second inlet may be positioned between the mixing element and the outlet.

[0014] Preferably, the inlet opening is located in a sidewall of the container. The sidewall or walls of the container are areas of the container that are substantially perpendicular to the plane along which the mixing element moves during mixing. In embodiments where the container is cylindrical and the mixing element is a rotating disk, the sidewall or walls are substantially perpendicular to the plane along which the rotating disk rotates. Thus, in such embodiments, the sidewall or walls are substantially parallel to the axis of rotation of the rotating disk. Furthermore, during use, the sidewall or walls of the container are often substantially perpendicular to the ground.

[0015] Preferably, the second inlet opening is located in the upper wall of the container. The upper wall of the container is the boundary of the container that is substantially parallel to the plane along which the mixing element moves during mixing in use. The upper wall can also be considered the highest boundary of the container in use.

[0016] Preferably, the second inlet can be spaced apart from the first inlet. In this context, the term spaced apart should be interpreted to mean that the first inlet and the second inlet are sufficiently spaced apart from each other so that the raw materials they supply are substantially contained in a slurry before they interact. Preferably, the first inlet and the second inlet are vertically spaced apart from each other within the vessel. Preferably, the first inlet and the second inlet are horizontally spaced apart from each other within the vessel. Preferably, the first inlet and the second inlet are spaced apart from each other around the vessel. More preferably, the first inlet and the second inlet are spaced apart from each other in two or more dimensions (for example, but not limited to, vertically and around the vessel).

[0017] In this way, the aqueous foam introduced through the first inlet can be kept separate from other ingredients introduced through the second inlet during the initial stages of mixing. This feature can be particularly advantageous when a hydrophobic additive is introduced into the vessel through the second inlet, as separating the aqueous foam from the hydrophobic additive during the initial stages of mixing is believed to enhance foam efficiency.

[0018] The present invention may prove beneficial when mixing stucco slurries used in the manufacture of moisture-resistant plasterboard. Slurries for the manufacture of moisture-resistant plasterboard contain hydrophobizing additives that have the effect of destabilizing aqueous foam. This destabilizing effect is particularly evident when the hydrophobizing additive contains siloxane oil (e.g., polymethylhydrogensiloxane) or is siloxane oil-based.

[0019] The present invention may also prove beneficial when mixing stucco slurries containing a high percentage of recycled plaster materials, as these recycled materials may contain a significant proportion of hydrophobic materials. Without proper control, as provided in the present invention, this hydrophobic material can significantly destabilize the aqueous foam during mixing, potentially resulting in production losses (reduced foam volume during mixing). Furthermore, given the continuing trend toward recycling materials, the proportion of recycled material in future plasterboards is likely to increase in the future, increasing the importance of this issue. The hydrophobic gypsum particles introduced into the slurry may come from recycled moisture-resistant products and recovered sawing and trimming dust.

[0020] When recycled materials are used to produce moisture resistant plasterboard, the above effects can combine to have a very strong destabilizing effect on aqueous foam unless precisely controlled as in the present invention.

[0021] The first inlet may be located adjacent the periphery of the container and the second inlet may be located adjacent the center of the container, so that ingredients such as foam introduced through the first inlet may be kept away from ingredients such as hydrophobic additives introduced through the second inlet for a longer period of time than in an arrangement in which each of the inlets is positioned adjacent to one another.

[0022] Preferably, the first inlet and outlet are spaced apart from one another. In this context, the term spaced apart should be interpreted to mean that the first inlet and outlet are sufficiently spaced apart from one another so that aqueous foam can be mixed throughout the stucco slurry to render the stucco slurry generally homogeneous. Preferably, the first inlet and outlet are spaced apart from one another vertically within the vessel. Preferably, the first inlet and outlet are spaced apart from one another horizontally within the vessel. Preferably, the first inlet and outlet are spaced apart from one another around the periphery of the vessel. More preferably, the first inlet and outlet are spaced apart from one another in two or more dimensions (e.g., but not limited to, vertically and around the periphery of the vessel).

[0023] Preferably, the first inlet and outlet are positioned such that, in use, the aqueous foam travels along a substantially spiral path from the first inlet to the outlet.

[0024] The inlet opening may be elliptical or oval in shape. Alternatively, the inlet opening may be slot-shaped, such as a curved slot or a C-shaped slot. In this way, the back pressure experienced at the inlet opening may be reduced compared to other shapes, such as a circle.

[0025] The tangent line may be the tangent line of the mixing path at a point adjacent the inlet opening.

[0026] The inlet conduit may extend from the inlet opening such that the relative angle between the longitudinal axis of the inlet conduit and the tangent to the mixing path is between 89 and 0 degrees. Alternatively, the inlet conduit may extend from the inlet opening such that the relative angle between the longitudinal axis of the inlet conduit and the tangent to the mixing path is between 70 and 0 degrees. Alternatively, the inlet conduit may extend from the inlet opening such that the relative angle between the longitudinal axis of the inlet conduit and the tangent to the mixing path is between 45 and 0 degrees. Alternatively, the inlet conduit may extend from the inlet opening such that the relative angle between the longitudinal axis of the inlet conduit and the tangent to the mixing path is between 30 and 0 degrees. Alternatively, the inlet conduit may extend from the inlet opening such that the relative angle between the longitudinal axis of the inlet conduit and the tangent to the mixing path is between 20 and 0 degrees.

[0027] The inlet conduit may extend from the inlet opening such that the relative angle between the longitudinal axis of the inlet conduit and the tangent to the mixing path is less than 89 degrees. Alternatively, the inlet conduit may extend from the inlet opening such that the relative angle between the longitudinal axis of the inlet conduit and the tangent to the mixing path is less than 70 degrees. Alternatively, the inlet conduit may extend from the inlet opening such that the relative angle between the longitudinal axis of the inlet conduit and the tangent to the mixing path is less than 45 degrees. Alternatively, the inlet conduit may extend from the inlet opening such that the relative angle between the longitudinal axis of the inlet conduit and the tangent to the mixing path is less than 30 degrees. Alternatively, the inlet conduit may extend from the inlet opening such that the relative angle between the longitudinal axis of the inlet conduit and the tangent to the mixing path is less than 20 degrees.

[0028] The inlet conduit may extend from the inlet opening such that the longitudinal axis of the inlet conduit is parallel to a tangent to the mixing path. In this manner, the direction and / or velocity of movement of the foam introduced through the first inlet may more closely match the direction and / or velocity of movement of the stucco slurry being mixed in the vessel adjacent the first inlet, resulting in reduced shear forces on the foam.

[0029] The vessel may further include a third inlet. Preferably, the third inlet includes a third inlet opening in the vessel wall and a third inlet conduit extending therefrom, wherein the relative angle between the longitudinal axis of the third inlet conduit and a tangent to the mixing path is less than 90 degrees. Any of the features described above with respect to the first inlet may also be applied to the third inlet. Preferably, the third inlet may be spaced apart from the first inlet. Furthermore, multiple inlets may allow foam to be introduced at multiple locations, thereby improving the homogeneity of the slurry. Additionally, multiple inlets may reduce the back pressure experienced by each inlet. Therefore, the individual shear levels experienced at each inlet may be reduced. Preferably, the mixing element is positioned between the third inlet and the outlet. Alternatively, the third inlet may be positioned between the mixing element and the outlet.

[0030] The outlet comprises an outlet opening. The outlet may further comprise an outlet conduit. Preferably, the outlet conduit deviates from the direction of rotation of the mixing element as it moves away from the outlet opening. In this manner, the path of the outlet conduit may be aligned with the direction of movement of the stucco slurry being mixed in the vessel adjacent the outlet opening. Thus, the slurry may not be compressed and / or otherwise affected to the extent that air bubbles in the slurry are destroyed when the slurry is removed from the vessel. The outlet opening may be an opening in the wall of the vessel. The outlet conduit may comprise a pipe, a tube, and / or any other structure suitable for transporting a slurry. The outlet conduit may be linear. The outlet conduit may be straight. Alternatively, the outlet conduit may be curved. The outlet conduit may comprise a straight portion immediately adjacent the outlet opening and a curved portion extending from the straight portion. In this manner, the overall volume of the mixing device may be reduced while still providing a straight outlet conduit portion adjacent the outlet opening.

[0031] The outlet conduit may extend from the outlet opening such that the relative angle between the longitudinal axis of the outlet conduit and another tangent to the mixing path is between 89 and 0 degrees. The other tangent may be a tangent to the mixing path at a point adjacent to the outlet opening. Alternatively, the outlet conduit may extend from the outlet opening such that the relative angle between the longitudinal axis of the outlet conduit and another tangent to the mixing path is between 70 and 0 degrees. Alternatively, the outlet conduit may extend from the outlet opening such that the relative angle between the longitudinal axis of the outlet conduit and another tangent to the mixing path is between 45 and 0 degrees. Alternatively, the outlet conduit may extend from the outlet opening such that the relative angle between the longitudinal axis of the outlet conduit and another tangent to the mixing path is between 30 and 0 degrees. Alternatively, the outlet conduit may extend from the outlet opening such that the relative angle between the longitudinal axis of the outlet conduit and another tangent to the mixing path is between 20 and 0 degrees.

[0032] The outlet conduit may extend from the outlet opening such that the relative angle between the longitudinal axis of the outlet conduit and another tangent to the mixing path is less than 90 degrees. The other tangent may be a tangent to the mixing path at a point adjacent to the outlet opening. Alternatively, the outlet conduit may extend from the outlet opening such that the relative angle between the longitudinal axis of the outlet conduit and another tangent to the mixing path is less than 70 degrees. Alternatively, the outlet conduit may extend from the outlet opening such that the relative angle between the longitudinal axis of the outlet conduit and another tangent to the mixing path is less than 45 degrees. Alternatively, the outlet conduit may extend from the outlet opening such that the relative angle between the longitudinal axis of the outlet conduit and another tangent to the mixing path is less than 30 degrees. Alternatively, the outlet conduit may extend from the outlet opening such that the relative angle between the longitudinal axis of the outlet conduit and another tangent to the mixing path is less than 20 degrees.

[0033] Alternatively, the outlet conduit may extend from the outlet opening regardless of the direction and / or orientation of the mixing path, for example, the outlet opening may be located at the lowest point of the container and the outlet conduit may extend downwardly therefrom.

[0034] The outlet conduit may include a separate inlet. Thus, foam may be introduced directly into the outlet conduit via the separate inlet. It is also envisioned that foam may be introduced directly into the outlet. The outlet conduit may include a valve and / or a cover. The valve and / or cover may be configured to selectively close the outlet.

[0035] If the slurry mixing device comprises multiple outlets, only one of the outlets, all of the outlets, or selected outlets may comprise any one or more of the features described herein above, either alone or in combination.

[0036] The outlet allows the mixed stucco slurry to be removed from the container. The outlet may transport the mixed stucco slurry from the container to another device configured to produce plasterboard from the stucco slurry. Preferably, the slurry mixing device may include multiple outlets. Providing multiple outlets may reduce the velocity of the mixed stucco slurry exiting the container. Thus, the level of shear experienced by the mixed stucco slurry and the foam contained therein may be reduced. Thus, the amount of foam bubbles destroyed during mixing may be reduced.

[0037] It should be understood that any combination of inlet locations relative to the mixing element and one or more outlets is contemplated. For example, the first inlet and second inlet can be located on a first side of the mixing element, and the third inlet and one or more outlets can be located on a second side of the mixing element. In particular, the mixing element can separate the vessel into upper and lower portions, with the first inlet and second inlet located on the upper portion and the third inlet and one or more outlets located on the lower portion.

[0038] The mixing path can be the path along which the stucco slurry being mixed moves around the vessel. The stucco slurry can form a rotating slurry vortex during mixing. The mixing path can be the path along which the rotating slurry vortex moves within the vessel. The mixing path can be defined by the movement of a single element of the mixing element. For example, the mixing path can be formed by tracking the end or edge of the mixing element as it moves. The mixing path can be round, circular, curved, elliptical, oval, or any other non-linear shape.

[0039] Preferably, the first inlet and outlet are positioned such that, during use, the average residence time of the aqueous foam in the vessel is within 30% of the average residence time of the other components of the stucco slurry in the vessel. More preferably, during use, the average residence time of the aqueous foam in the vessel is within 20% of the average residence time of the other components of the stucco slurry in the vessel. Even more preferably, during use, the average residence time of the aqueous foam in the vessel is within 10% of the average residence time of the other components of the stucco slurry in the vessel. Most preferably, during use, the average residence time of the aqueous foam in the vessel is within 5% of the average residence time of the other components of the stucco slurry in the vessel.

[0040] The vessel may be a mixing chamber. The vessel may be cylindrical or any other known shape. The vessel may be watertight except for the inlet and outlet. At least one sensor may be provided to monitor a property (e.g., temperature or density) of the slurry being mixed in the vessel. Operation of the mixing device may be automated. Accordingly, necessary sensors and controls may be provided. The inlet opening may be located in a curved wall of the cylindrical vessel. The outlet may also be located in a curved wall of the cylindrical vessel. Alternatively, the outlet may be located in a flat wall of the cylindrical vessel. In embodiments including multiple outlets, outlets may be provided in both the curved and flat walls of the cylindrical vessel.

[0041] The mixing member may be a mixing disk. The mixing disk may comprise a plurality of teeth arranged on or along the circumference or curved surface of the disk. The plurality of teeth may be arranged so that the entire circumference or curved surface of the disk is toothed. The mixing disk may comprise a plurality of teeth arranged on at least one substantially flat surface of said disk. The plurality of teeth may be arranged so that the entire plane of at least one plane of the disk is toothed.

[0042] Alternatively, the mixing element may be a mixing arm. The mixing element may be configured to rotate within the vessel. The mixing element may agitate, stir, mix, or otherwise contain the raw materials within the vessel into a homogeneous slurry. The mixing element may be removable from the vessel for maintenance and / or replacement. The mixing element may be an elongated element. The mixing element may be helical such that the stucco slurry is moved by the mixing element from a first region of the vessel to a second region of the vessel during movement of the mixing element.

[0043] The mixing member may include multiple mixing discs and / or arms. Each mixing disc and / or mixing arm may move in a different direction or at a different speed than at least one other mixing disc and / or mixing arm. Each mixing disc and / or mixing arm may be configured to rotate about a common axis. Alternatively, each mixing disc and / or mixing arm may be configured to rotate about a different axis than at least one other mixing disc and / or mixing arm.

[0044] The first inlet may include a valve and / or a cover configured to selectively close the first inlet.

[0045] Preferably, the second inlet comprises a second inlet conduit extending such that the relative angle between the longitudinal axis of the second inlet conduit and a tangent to the mixing path is less than 90 degrees. Any of the features described above with respect to the first inlet may also be applied to the second inlet.

[0046] The apparatus may further include a scraper configured to remove raw material adhering to the inner surface of the container. The scraper may include at least one rotating member. The scraper may be configured to scrape the inner surface of the top wall of the container during use. The scraper may at least partially prevent accumulation of raw material on the inner surface of the container. The inlet, or each inlet (if there are multiple), may be positioned between the scraper and the mixing member.

[0047] The slurry can be a suspension or a solution. Stucco can be calcium sulfate hemihydrate with the chemical formula CaSO₄·½H₂O. Thus, the slurry can contain water and stucco. The slurry can further contain one or more additives, such as fibers, hydrophobic additives such as silicone oil, recycled materials such as previously manufactured plasterboard, phosphates, and acids, among others. Some additives, such as hydrophobic additives and recycled materials, can destroy foam on contact. Therefore, when producing stucco slurries containing such additives, it is desirable to maximize foaming efficiency.

[0048] In a second aspect of the present invention, there is provided a method of mixing stucco slurry using the stucco slurry mixing apparatus of the first aspect of the present invention, comprising: introducing a feedstock comprising at least an aqueous foam into a vessel via the first inlet; introducing another raw material into the vessel through a second inlet; moving a mixing element to mix the raw materials within the vessel; and removing the mixed slurry from the vessel through an outlet. A mixing method comprising: A mixing method is also described in which the average residence time of the aqueous foam in the vessel is similar to the average residence time of the other components of the stucco slurry in the vessel.

[0049] Thus, a method is provided for incorporating aqueous foam into a stucco slurry within a vessel.

[0050] Preferably, the average residence time of the aqueous foam in the vessel is within 30% of the average residence time of the other components of the stucco slurry in the vessel. More preferably, during use, the average residence time of the aqueous foam in the vessel is within 20% of the average residence time of the other components of the stucco slurry in the vessel. Even more preferably, during use, the average residence time of the aqueous foam in the vessel is within 10% of the average residence time of the other components of the stucco slurry in the vessel. Most preferably, during use, the average residence time of the aqueous foam in the vessel is within 5% of the average residence time of the other components of the stucco slurry in the vessel.

[0051] Preferably, the aqueous foam is the only ingredient introduced into the stucco slurry via the first inlet.

[0052] Preferably, the other raw material introduced into the stucco slurry via the second inlet comprises at least one hydrophobic material. The hydrophobic material may comprise a solid. The hydrophobic material may comprise a liquid.

[0053] Preferably, the other raw material introduced into the stucco slurry via the second inlet comprises a solid material. More preferably, the other raw material introduced into the stucco slurry via the second inlet consists essentially of a solid material. Most preferably, the other raw material introduced into the stucco slurry via the second inlet consists of a solid material. It is contemplated that the solid material may be hydrophobic.

[0054] An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0055] [Figure 1] FIG. 2 is a schematic cross-sectional plan view of a first stucco slurry mixer. [Figure 2] FIG. 2 is a schematic side cross-sectional view of the stucco slurry mixer shown in FIG. 1. [Figure 3] FIG. 2 is a schematic cross-sectional plan view of a second stucco slurry mixer. [Figure 4] FIG. 4 is a schematic side cross-sectional view of the stucco slurry mixer shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0056] FIG. 1 is a schematic cross-sectional plan view of a first stucco slurry mixer 100. Mixer 100 includes a cylindrical mixing chamber 110. A mixing arm 120 is disposed within mixing chamber 110 and configured to rotate about a center of rotation 122. While mixing arm 120 is shown rotating clockwise in the orientation shown in FIG. 1, counterclockwise rotation of mixing arm 120 is also contemplated. Rotation of mixing arm 120 about rotation point 122 defines a circular mixing path 124. The mixing path 124 shown in FIG. 1 is defined by the movement of one end 126 of mixing arm 120.

[0057] Mixer 100 includes a first inlet 130. Mixer 100 further includes a second inlet, which will be described in more detail with reference to FIG. 2 below. First inlet 130 includes an inlet opening 132 in the curved wall of cylindrical mixing chamber 110. First inlet 130 further includes an inlet conduit 134 extending from inlet opening 132. Inlet conduit 134 extends in a direction opposite to the direction of mixing path 124 and away from mixing chamber 110. In particular, in the orientation shown in FIG. 1 , mixing path 124 has a generally upward direction at a point adjacent first inlet 130, and inlet conduit 134 extends in a generally downward direction from mixing chamber 110.

[0058] The inlet conduit 134 of the first inlet 130 extends in a direction away from the mixing chamber 110 such that the longitudinal axis 136 of the inlet conduit 134 is parallel to and spaced apart from a first tangent 140 to the circular mixing path 124. The first tangent 140 is a tangent to the mixing path 124 at a point adjacent the inlet opening 132. Thus, ingredients such as aqueous foam may be introduced into the mixing chamber 110 through the first inlet 130 in a direction tangential to the direction of movement of other ingredients already present in the mixing chamber 110 as they travel around the mixing path 124.

[0059] The mixer 100 further includes an outlet 150. The outlet 150 includes an outlet opening 152 in the curved wall of the cylindrical mixing chamber 110. The outlet 150 further includes an outlet conduit 154 extending from the outlet opening 152. The outlet conduit 154 extends in a direction away from the mixing chamber 110 in a direction toward the mixing path 124. In particular, in the orientation shown in FIG. 1 , the mixing path 124 has a generally downward direction at a point adjacent the outlet 150, and the outlet conduit 154 extends in a generally downward direction from the mixing chamber 110. Here, the first inlet 130 and the outlet 150 are spaced from one another such that the slurry exiting the outlet 150 is substantially homogeneous.

[0060] The outlet conduit 154 of the outlet 150 extends in a direction away from the mixing chamber 110 such that the longitudinal axis 156 of the inlet conduit 154 is parallel to and spaced apart from the second tangent 142 of the circular mixing path 124. The second tangent 142 is a tangent to the mixing path 124 at a point adjacent the outlet opening 152. Thus, the mixed slurry can be removed from the mixing chamber 110 through the outlet 150 in a direction tangential to the direction of movement of the mixed slurry as it travels around the mixing path 124 within the mixing chamber 110.

[0061] Figure 2 is a schematic side cross-sectional view of the stucco slurry mixer 100 shown in Figure 1. As shown in Figure 2, a mixing arm 120 is positioned between a first inlet 130 and an outlet 150. The mixer 100 further includes a second inlet 160, which is shown on the same side of the mixing arm 120 as the first inlet 130, such that the mixing arm 120 is positioned between the second inlet 160 and the outlet 150.

[0062] The inlet opening 132 is positioned in the curved wall 112 of the mixing chamber 110 near the top surface 114 of the mixing chamber 110. The inlet conduit 134 extends away from the cylindrical mixing chamber 110 such that the longitudinal axis 136 of the inlet conduit 134 is parallel to, spaced apart from, and above the plane 128 in which the mixing arm 120 lies.

[0063] The outlet opening 152 is positioned in the curved wall 112 of the mixing chamber 110 near the lower surface 116 of the mixing chamber 110. The outlet conduit 154 extends away from the cylindrical mixing chamber 110 such that the longitudinal axis 156 of the outlet conduit 154 is parallel to, spaced apart from, and below the plane 128 in which the mixing arm 120 lies.

[0064] To mix a slurry using the mixer 100 shown in FIGS. 1 and 2 , raw materials such as stucco, water, and any desired additives can be introduced into the mixing chamber 110 through the second inlet 160. The mixing arm 120 can then rotate to mix the raw materials into the stucco slurry. As the slurry is moved by the mixing arm 120, foam can be introduced through the first inlet 130. The tangential orientation of the first inlet 130 minimizes the shear stress experienced by the foam as it enters the mixing chamber 110. The movement of the slurry and the movement of the mixing arm 120 can uniformly distribute the foam throughout the slurry. Once the slurry and foam are mixed to the desired degree, the mixed slurry can be removed from the mixing chamber 110 through the outlet 150. The tangential orientation of the outlet 150 minimizes the shear stress experienced by the foam as it exits the mixing chamber 110.

[0065] FIG. 3 is a schematic cross-sectional plan view of a second stucco slurry mixer 200. The mixer 200 includes a cylindrical mixing chamber 210. A mixing disk 220 is disposed within the mixing chamber 210 and configured to rotate about a rotation center point 222. The mixing disk 220 includes several teeth 226 along its outer edge. Although the teeth 226 are shown spaced apart in FIG. 3, the teeth 226 may be adjacent. Thus, more teeth 226 than shown in FIG. 3 may be provided. While the mixing disk 220 is shown rotating clockwise in the orientation shown in FIG. 3, counterclockwise rotation of the mixing disk 220 is also contemplated. The rotation of the mixing disk 220 about the rotation center point 222 defines a circular mixing path 224. The mixing path 224 shown in FIG. 2 is defined by the movement of one end of the teeth 226 of the mixing disk 220.

[0066] Mixer 200 includes a first inlet 230. Mixer 200 further includes a second inlet, which is described in more detail with reference to FIG. 4 below. First inlet 230 includes an inlet opening 232 in the curved wall of cylindrical mixing chamber 210. First inlet 230 further includes an inlet conduit 234 extending from inlet opening 232. Inlet conduit 234 extends in a direction opposite to the direction of mixing path 224 and away from mixing chamber 210. In particular, in the orientation shown in FIG. 3, mixing path 224 has a generally upward direction at a point adjacent first inlet 230, and inlet conduit 234 extends in a generally downward direction from mixing chamber 210.

[0067] The inlet conduit 234 of the first inlet 230 extends in a direction away from the mixing chamber 210 such that the longitudinal axis 236 of the inlet conduit 234 is parallel to and spaced apart from a first tangent 240 to the circular mixing path 224. The first tangent 240 is a tangent to the mixing path 224 at a point adjacent the inlet opening 232. Thus, an ingredient, such as an aqueous foam, can be introduced into the mixing chamber 210 through the first inlet 230 in a direction tangent to the direction of movement of other ingredients already present in the mixing chamber 210 as those ingredients move around the mixing path 224.

[0068] The mixer 200 further includes an outlet, not shown in FIG. 3, which is described in more detail below with reference to FIG.

[0069] Figure 4 is a schematic cross-sectional side view of the second stucco slurry mixer 200 shown in Figure 3. The outlet 250 includes three outlet openings positioned in the lower surface 216 of the mixing chamber 210, with respective outlet conduits extending from the outlet openings. The outlet conduits extend away from the outlet openings in a direction away from the lower surface 216 of the mixing chamber 210. In the orientation shown in Figure 4, the outlet conduits extend downward.

[0070] 4, the mixing disc 220 is positioned between the first inlet 230 and the outlet 250. The mixer 200 further includes a second inlet 260, which is shown on the same side of the mixing disc 220 as the first inlet 230, such that the mixing disc 220 is positioned between the second inlet 260 and the outlet 250.

[0071] The inlet opening 232 is positioned in the curved wall 212 of the mixing chamber 210 near the top surface 214 of the mixing chamber 210. The inlet conduit 234 extends away from the cylindrical mixing chamber 210 such that the longitudinal axis 236 of the inlet conduit 234 is parallel to, spaced apart from, and above the plane in which the mixing disc 220 lies.

[0072] To mix a slurry using the mixer 200 shown in Figures 3 and 4, raw materials such as stucco, water, and any desired additives can be introduced into the mixing chamber 210 through the second inlet 260. The mixing disk 220 can then be rotated to mix the raw materials into the stucco slurry. As the slurry is moved by the mixing disk 220, foam can be introduced through the first inlet 230. The tangential orientation of the first inlet 230 minimizes the shear stress experienced by the foam as it enters the mixing chamber 210. The movement of the slurry and the movement of the mixing disk 220 can uniformly distribute the foam throughout the slurry. Once the slurry and foam have been mixed to the desired degree, the mixed slurry can be removed from the mixing chamber 210 through the outlet 250.

Claims

1. a container for receiving and mixing the raw materials; a mixing element configured to move within the vessel and mix ingredients contained within the vessel, the movement of the mixing element defining a non-linear mixing path; A stucco slurry mixing apparatus comprising: The container comprises: a first inlet for introducing raw materials, including at least an aqueous foam, into the vessel, the first inlet comprising an inlet opening in a wall of the vessel and an inlet conduit extending therefrom, the relative angle between a longitudinal axis of the inlet conduit and a tangent to the mixing path at a point adjacent the inlet opening being less than 90 degrees; a second inlet comprising a second inlet opening in a wall of the vessel for the introduction of another ingredient into said vessel; outlet for mixed slurry and Equipped with a stucco slurry mixing apparatus, wherein the first inlet and the outlet are positioned such that, during use, the average residence time of the aqueous foam within the vessel is within 30% of the average residence time of other components of the stucco slurry within the vessel.

2. 10. The stucco slurry mixing apparatus of claim 1, wherein the inlet conduit extends from the inlet opening in a direction away from the direction of rotation of the mixing element.

3. 3. The stucco slurry mixing apparatus of claim 1 or claim 2, wherein the mixing path lies entirely in a single plane, and the longitudinal axis of the inlet conduit lies parallel to and spaced apart from the plane in which the mixing path lies.

4. The stucco slurry mixing apparatus of any one of claims 1 to 3, wherein the mixing element is positioned between the first inlet and the outlet.

5. The stucco slurry mixing apparatus of any one of claims 1 to 4, wherein the mixing element is positioned between the second inlet and the outlet.

6. The stucco slurry mixing apparatus of any one of claims 1 to 5, wherein the inlet opening is located in a sidewall of the vessel.

7. The stucco slurry mixing apparatus of any one of claims 1 to 6, wherein the second inlet opening is located in a top wall of the vessel.

8. The stucco slurry mixing apparatus of any one of claims 1 to 7, wherein the second inlet is spaced apart from the first inlet.

9. The stucco slurry mixing apparatus of any one of claims 1 to 8, wherein the inlet opening is elliptical or oval.

10. 10. The stucco slurry mixing apparatus of any one of claims 1 to 9, wherein the inlet conduit extends from the inlet opening such that the relative angle between the longitudinal axis of the inlet conduit and the tangent to the mixing path is less than 45 degrees.

11. 11. The stucco slurry mixing apparatus of any one of claims 1 to 10, wherein the inlet conduit extends from the inlet opening such that the relative angle between the longitudinal axis of the inlet conduit and the tangent to the mixing path is less than 20 degrees.

12. 12. The stucco slurry mixing apparatus of any one of claims 1 to 11, wherein the inlet conduit extends from the inlet opening such that the longitudinal axis of the inlet conduit is parallel to the tangent to the mixing path.

13. The stucco slurry mixing apparatus of any one of claims 1 to 12, wherein the vessel further comprises a third inlet.

14. 14. The stucco slurry mixing apparatus of any one of claims 1 to 13, wherein the outlet comprises an outlet opening and an outlet conduit extending therefrom, the outlet conduit diverging from a direction of rotation of the mixing element as it moves away from the outlet opening.

15. 15. The stucco slurry mixing apparatus of claim 14, wherein the relative angle between the longitudinal axis of the outlet conduit and a tangent to the mixing path at a point adjacent the outlet opening is less than 90 degrees.

16. The stucco slurry mixing apparatus of any one of claims 1 to 15, wherein the mixing path is circular.

17. 17. The stucco slurry mixing apparatus of any one of claims 1 to 16, wherein, during use, the average residence time of the aqueous foam in the vessel is within 20% of the average residence time of other components of the stucco slurry in the vessel.

18. 18. A method of mixing a stucco slurry using the stucco slurry mixing apparatus of any one of claims 1 to 17, comprising the steps of introducing raw materials including at least an aqueous foam into a vessel through a first inlet, introducing another raw material into the vessel through a second inlet, moving a mixing element to mix the raw materials within the vessel, and removing the mixed slurry from the vessel through an outlet, wherein an average residence time of the aqueous foam in the vessel is within 30% of an average residence time of other components of the stucco slurry in the vessel.

19. 20. The method of claim 18, wherein the aqueous foam is the only ingredient introduced into the stucco slurry through the first inlet.

20. 20. The method of claim 18 or claim 19, wherein another ingredient introduced into the stucco slurry via the second inlet comprises at least one hydrophobic material.

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