Equipment and methods for manufacturing foamed cement slurry

Abstract

According to the present invention, an apparatus (100) for manufacturing a foam-containing cement slurry is provided, the apparatus comprising: a mixing chamber (105) for mixing cementitious materials and water to form a cement slurry; a channel (110) fluidly connected at a first end to the mixing chamber (105), the channel (110) for receiving the cement slurry from the mixing chamber (105), the channel (110) extending from the first end (110a) and terminating at least one second end (110b); the apparatus comprising a foam inlet (125) for introducing foam into the mixing chamber (105) or the channel (110); the apparatus (100) further comprising a coalescence inhibitor inlet (130) for introducing a coalescence inhibitor into the cement slurry downstream of the foam inlet (125). A method of using the apparatus is also described.

Description

Technical Field

[0001] This invention relates to apparatus for manufacturing foamed cement slurry. The invention also relates to a method for manufacturing foamed cement slurry using said apparatus. Background Technology

[0002] Gypsum exists naturally as a raw material in the form of calcium sulfate dihydrate (CaSO4 2(H2O)). Gypsum-containing products, such as gypsum board, are prepared by mixing calcined or dehydrated gypsum (i.e., calcium sulfate hemihydrate (CaSO4 0.5(H2O))) with water to form a solidifiable slurry, which is then cast into a predetermined shape. Calcium sulfate hemihydrate reacts with water and rehydrates to form dihydrate crystals, which are then solidified or dried to a solid state.

[0003] Due to its versatility, ideal mechanical properties, and the possibility of achieving high-level surface finishes, gypsum products are ubiquitous in buildings. Therefore, there is a demand for gypsum products. Reducing the amount of gypsum used in manufacturing these products can significantly reduce the resource requirements of the manufacturing process, thereby lowering material costs. Furthermore, reducing the weight of gypsum products improves their ease of handling and processing.

[0004] To provide lightweight gypsum products, foam can be added to a settable gypsum slurry. When foam is added to the slurry, the air bubbles within the foam disperse throughout the slurry, reducing its density. During the setting process, the air bubbles persist, forming voids in the final gypsum product. In this way, the density of the final gypsum product is reduced. Since the voids in the final gypsum product are formed by foam air bubbles in the gypsum slurry, the size of the foam air bubbles is related to the size of the voids.

[0005] Given the above, controlling the size of foam and air bubbles in gypsum slurry is crucial during the manufacturing process of lightweight gypsum products. If unstable foam is introduced into the gypsum slurry, the air bubbles within the foam will coalesce. Therefore, to similarly control the porosity of the final gypsum product, it is necessary to control the coalescence of foam and air bubbles in the gypsum slurry.

[0006] However, no foam exists in isolation within gypsum slurry. Gypsum products typically contain additives to control and / or improve other properties of the final gypsum product, such as its water resistance. In addition to altering the properties of the final gypsum product, many of these additives can also inhibit foam and / or the coalescence of air bubbles in the gypsum slurry. Therefore, controlling the size of air bubbles in gypsum slurry to maintain the desired porosity in gypsum products is complex and challenging, and is influenced by a variety of factors. Summary of the Invention

[0007] According to a first aspect of the invention, an apparatus for producing a foam-containing cement slurry is provided, the apparatus comprising: a mixing chamber for mixing cementitious materials and water to form a cement slurry; a channel fluidly connected at a first end to the mixing chamber for receiving the cement slurry from the mixing chamber; the channel extending from the first end and terminating at least one second end; the apparatus including a first inlet for introducing foam into the mixing chamber or the channel; and the apparatus further including a second inlet for introducing a coalescence inhibitory additive into the cement slurry downstream of the first inlet.

[0008] This invention provides an apparatus for efficiently and consistently combining foam with cementitious slurry (such as plaster or gypsum slurry). In the prior art, when foam is introduced, the presence of many additives in the slurry partially or completely inhibits coalescence, thereby stabilizing the air bubbles in the foam-slurry mixture. This invention solves this problem of the prior art because coalescence-inhibiting additives can be added after sufficient coalescence has occurred.

[0009] Preferably, the channel includes a plurality of second ends. Alternatively, the channel includes a single second end.

[0010] Preferably, the at least one second end of the channel is connected to a distribution pipe. More preferably, the distribution pipe includes a plurality of slurry outlets. Even more preferably, the distribution pipe includes a plurality of equivalent slurry outlets. When the distribution pipe includes multiple outlets, this helps to ensure that the cement slurry is evenly distributed in one area when leaving the equipment.

[0011] Alternatively, at least one second end of the channel is connected to a secondary chamber. When the at least one second end of the channel is connected to a secondary chamber, this can advantageously provide further mixing for the cement slurry.

[0012] Preferably, the second inlet is located between the first inlet and at least one second end of the channel. Alternatively, the second inlet is located in the secondary chamber. In this way, any additives that inhibit coalescence can be added to the cement slurry downstream of the first inlet to ensure sufficient bubble coalescence.

[0013] In some embodiments, the first inlet includes a plurality of first inlets. In this way, foam can be introduced at multiple points in the device. Preferably, at least one of the plurality of first inlets is located in the mixing chamber. Preferably, at least one of the plurality of first inlets is located in the channel. In some embodiments, at least one of the plurality of first inlets is located in both the mixing chamber and the channel.

[0014] Preferably, the second inlet includes a fluid inlet. More preferably, the second inlet includes a fluid inlet. In this way, liquid coalescence inhibitors can be introduced into the cement slurry.

[0015] Preferably, the device further includes a third inlet for introducing a coalescence promoter into the cement slurry. Preferably, the third inlet is located upstream of the second inlet. Preferably, the third inlet is located downstream of the first inlet. Therefore, bubble coalescence can be promoted after the foam is introduced into the cement slurry and before the coalescence inhibitor is introduced.

[0016] Preferably, the third inlet is located in the channel. Alternatively, the third inlet is located in the mixing chamber. Alternatively, the third inlet is combined with the first inlet.

[0017] Preferably, the distance between the third inlet and the first inlet is less than the distance between the third inlet and the second inlet. This increases the effect of the coalescence promoter on bubble coalescence. More preferably, the third inlet is adjacent to the first inlet.

[0018] Alternatively, the third entrance may be located closer to the second entrance than the first entrance.

[0019] Preferably, the third inlet includes a fluid inlet. More preferably, the third inlet consists of a fluid inlet. In this way, a liquid coalescence promoter can be introduced into the cement slurry.

[0020] Alternatively, the first inlet is configured to introduce a coalescence accelerator into the cement slurry. In this way, foam and at least one coalescence accelerator can be introduced into the slurry simultaneously or independently through the first inlet. For example, the coalescence accelerator and foam can be mixed together before being introduced into the cement slurry through the first inlet.

[0021] Preferably, the mixing chamber is a tangential mixing chamber. Preferably, the tangential mixer comprises a single mixing component. Alternatively, the tangential mixer comprises multiple mixing components.

[0022] Preferably, the channel is substantially straight. In selected embodiments, the channel is substantially curved. Preferably, the channel has a substantially similar cross-sectional area over its entire length. Preferably, the channel has a substantially similar cross-sectional shape over its entire length. More preferably, the channel has both substantially similar cross-sectional areas and substantially similar cross-sectional shapes over its entire length. In some embodiments, the channel has the same cross-sectional area over its entire length. In some embodiments, the channel has the same cross-sectional shape over its entire length.

[0023] Preferably, the first inlet has a substantially circular cross-section. Alternatively, the first inlet has a substantially square or rectangular cross-section.

[0024] Preferably, the second inlet has a substantially circular cross-section. Alternatively, the second inlet has a substantially square or rectangular cross-section.

[0025] Preferably, the third inlet has a substantially circular cross-section. Alternatively, the third inlet has a substantially square or rectangular cross-section.

[0026] Preferably, the channel has a circular cross-section. Alternatively, the channel has a rectangular or square cross-section.

[0027] Preferably, the cement material includes at least one of calcium sulfate hemihydrate and calcium sulfate dihydrate. More preferably, the cement material is substantially composed of calcium sulfate hemihydrate.

[0028] According to a second aspect of the present invention, a method for manufacturing a foamed cement slurry is provided, the method comprising: providing the apparatus of the first aspect of the present invention; introducing cement material and water into the mixing chamber to form a cement slurry; introducing foam into the cement slurry through a first inlet; and introducing an agglomeration inhibitor into the cement slurry through a second inlet.

[0029] Preferably, the device includes the third inlet, and the method includes introducing a coalescence accelerator into the cement slurry through the third inlet. The coalescence accelerator can be any additive with expected or unexpected coalescence-promoting effects. Preferably, the coalescence accelerator is a liquid.

[0030] The coalescence inhibitor can be any additive that has the intended or unintentional effect of inhibiting coalescence. Preferably, the coalescence inhibitor comprises polycarboxylic acid ether (PCE). PCE has advantages in improving the fluidity of cement slurry; however, it has the undesirable effect of inhibiting the coalescence of air bubbles in cement slurry.

[0031] Alternatively, the coalescence inhibitory additive includes one or more of potassium sulfate (K₂SO₄), lithium sulfate (Li(II)SO₄), and / or zinc sulfate (ZnSO₄). Potassium sulfate, lithium sulfate, and zinc sulfate are known accelerators for advantageously shortening the reaction time required for the drying and hardening of cement slurry.

[0032] Preferably, the coalescence promoter comprises polynaphthalene sulfonate (PNS). Alternatively, the coalescence promoter comprises silicone oil.

[0033] The cementitious material comprises or is substantially composed of calcium sulfate hemihydrate (plaster). Preferably, the coalescence inhibitor is introduced in an amount of 0.1 to 2 wt% relative to the plaster. More preferably, the coalescence inhibitor is introduced in an amount of 0.1 to 1 wt% relative to the plaster. Preferably, the coalescence accelerator is introduced in an amount of 0.1 to 5 wt% relative to the plaster. More preferably, the coalescence accelerator is introduced in an amount of 0.1 to 1 wt% relative to the plaster. Attached Figure Description

[0034] Embodiments of the invention will now be described by way of example only and with reference to the accompanying drawings, wherein:

[0035] Figure 1 An embodiment of the device according to the first aspect of the present invention is described;

[0036] Figure 2 Depicting Figure 1 A schematic diagram of the equipment;

[0037] Figure 3 A method according to a second aspect of the present invention is described;

[0038] Figure 4A , 4B Images of bubbles forming in the cement slurry during factory testing, as well as the equipment used in each test, are depicted in 5A and 5B.

[0039] Figure 6 A schematic diagram of a device that falls outside the scope of this invention is depicted;

[0040] Figure 7 Depicting laboratory replication Figure 2 A schematic diagram of the equipment operation steps;

[0041] Figure 8 Depicting laboratory replication Figure 6 A schematic diagram of the equipment steps; and

[0042] Figure 9A , 9B Images 10A and 10B depict the bubbles that form in the cement slurry during laboratory testing, as well as the equipment used in each test. Detailed Implementation

[0043] refer to Figure 1 and Figure 2 The present invention illustrates an apparatus 100 for producing a foamed cement slurry according to a first aspect of the invention. The apparatus 100 includes a mixing chamber 105 for mixing cementitious materials and water to form a cement slurry. The mixing chamber 105 includes a cementitious material inlet 105a, such as an inlet for introducing mortar into the mixing chamber 105, and a water inlet 105b for introducing water into the mixing chamber 105.

[0044] The device 100 further includes a channel 110 extending from a first end 110a and terminating at a second end 110b. The channel 110 is fluidly connected to a mixing chamber at the first end 110a. The channel 110 is configured to receive cement slurry from the mixing chamber 105.

[0045] The device 100 further includes a secondary chamber 115 and a distribution pipe 120 fluidly connected to the secondary chamber 115. A second end 110b of the channel 110 is connected to the secondary chamber 115 such that the channel 110 is connected to the distribution pipe. Cement slurry is configured to exit from the second end 110b of the channel 110, pass through the secondary chamber 115, and enter the distribution pipe 120.

[0046] The distribution pipe 120 is configured to distribute the cement slurry and foam mixture to, for example, a forming table 140, on which the cement slurry can be formed into a sheet or plate.

[0047] Secondary chamber 115 is fluidly connected to distribution pipe 120. The second end 110b of channel 110 is located at outlet 25 perpendicular to secondary chamber 115, such that cement slurry is configured to pass tangentially through secondary chamber 115. In this way, secondary chamber 115 further mixes cement slurry and foam, promoting the coalescence of bubbles formed in the mixture.

[0048] The device 100 further includes a pair of first inlets 125a, 125b, configured to introduce foam into the mixing chamber 105 and the channel 110. The primary inlet 125a of the pair of first inlets 125a, 125b is located in the mixing chamber 105, and the secondary inlet 125b of the pair of first inlets 125a, 125b is located in the channel 110, as shown below. Figure 2 As shown.

[0049] It is understood that the terms "main" and "secondary" refer to the location of the inlet in the upstream direction, rather than the importance of the inlet or the amount of foam introduced through that inlet. That is, the main inlet 125a is located upstream of the secondary inlet 125b. The secondary inlet 125b is located at the first end 110a of the channel. The pair of first inlets 125a, 125b are configured to connect to a foam source, such as a foam generating unit 135 including an air inlet, a water inlet, and a soap solution inlet.

[0050] The second inlet 130 is a fluid inlet located in channel 110 and is configured to introduce a coalescence inhibitor into the cement slurry. The second inlet 130 is located in channel 110 downstream of both the main inlet 125a and the auxiliary inlet 125b of a pair of first inlets 125a, 125b. The second inlet 130 is located between the auxiliary inlet 125b of the pair of first inlets 125a, 125b and the second end 110b of channel 110. In this way, the device is configured such that the coalescence inhibitor is introduced into the cement slurry downstream of the location where foam is introduced into the cement slurry.

[0051] The apparatus 100 further includes a third inlet 145 for optionally introducing a coalescence accelerator (such as polynaphthalene sulfonate (PNS)) into the apparatus 100. The third inlet 145 is located in the mixing chamber 105, upstream of the main inlet 125a of a pair of first inlets 125a, 125b. In this way, the coalescence accelerator promotes coalescence in the cement slurry as soon as the foam is introduced. Alternatively, the coalescence accelerator can be introduced into the cement slurry through one or more of the pair of first inlets 125a, 125b, for example, by mixing the coalescence accelerator with the foam before introducing the foam into the cement slurry.

[0052] like Figure 2 As shown, the distance between the third entrance 145 and the pair of first entrances 125 is less than the distance between the third entrance 145 and the second entrance 130.

[0053] Figure 3 A schematic diagram of a method 200 for producing a foamed cement slurry according to a second aspect of the present invention is shown. Method 200 includes providing 202 the apparatus 100 of the first aspect of the present invention. Method 200 further includes introducing cementitious materials and water into a mixing chamber 105 204 to form a cement slurry.

[0054] Method 200 further includes introducing foam into cement slurry 206 through a pair of first inlets 125a, 125b, and optionally introducing a coalescence promoting additive into cement slurry 208 through a third inlet 145 or one or more first inlets 125a, 125b.

[0055] Method 200 further includes the step of introducing a coalescence inhibitor into the cement slurry 210 through a second inlet 130.

[0056] Factory testing

[0057] Device 100 was used for factory testing to produce the results shown in Figures 4 and 5. The bubble size images were taken using a USB camera and an LED ring light.

[0058] Lightweight gypsum samples, namely gypsum boards, were produced with a thickness of 12.5 mm and a weight of 8.8 kg / m³.2 A linear velocity of 40 m / min is used. Cement material is introduced into equipment 100 at a rate of 10 L / s.

[0059] The cement material includes calcium sulfate hemihydrate (plaster), with a dosage of 7116 g / m³. 2 and 5975 g / m 2 The cement slurry was mixed with water. The water content of the cement slurry was 70%, and the concentration of the unstable soap solution was 0.4%. The flowability of the cement slurry was assessed by a slump test, which yielded a slump of 180 mm. The slump test was performed in a manner known in the art, wherein a spreading test was used to evaluate the viscosity of the slurry. The slurry was poured into a ring with a diameter of 5 cm and a height of 10 cm. The ring was then lifted, allowing the slurry to spread under gravity, and the slump was evaluated. The setting time of the cement slurry was tested using the knife-setting method, which yielded a setting time of 30 seconds. The knife-setting method was performed in a manner known in the art, wherein the knife-setting method allows for the measurement of the initial setting time of the slurry. The initial setting time corresponds to the time it takes for the slurry to undergo a liquid-to-solid transition.

[0060] Samples are cut from the produced sheet material, and the surfaces of these samples are ground to provide a clean surface for analyzing pore size distribution.

[0061] The position of the second inlet 130 was modified during testing to investigate the effect of the coalescence inhibitor introduction position relative to the foam introduction position.

[0062] Factory testing determined whether sufficient coalescence occurred in tests involving variations in the introduction location of the coalescence inhibitor additive. Sufficient coalescence was considered to have occurred if the median bubble diameter (measured using D50 distribution) was greater than 200 µm. Median bubble sizes greater than 200 µm would produce visible bubbles, such as... Figure 4A , 4B As shown in 5A.

[0063] The coalescence inhibitor introduced into device 100 through the second inlet 130 is polycarboxylic acid ether (PCE). The coalescence promoter introduced into the device through the third inlet 145 is polynaphthalene sulfonate (PNS).

[0064] control

[0065] As a control, in Figure 1 and Figure 2 No coalescence inhibitor additive was introduced into the second inlet 130 of the equipment 100. PNS was used as a coalescence promoter at 0.41 wt% (29.5 g / m³) relative to the mortar. 2 The amount of [amount] is introduced into the third inlet 145. The obtained equipment and bubble distribution are as follows: Figure 4A As shown. Figure 4A The image size is 16.6 mm x 12.5 mm.

[0066] Example 1

[0067] Device 100 was tested again in Example 1. The second inlet 130 is located at the end of channel 110, as... Figure 2 As shown. The distance between the second inlet 130 and the mixing chamber 105 is 2.25 m. The total length of the channel 110 is 2.25 m. PCE is used as a coalescence inhibitor at a concentration of 0.1 wt% (7 g / m³) relative to the mortar. 2 The amount of PNS was introduced into the cement slurry through the second inlet 130. PNS was used as a coalescence accelerator at a concentration of 0.41 wt% (29.5 g / m³) relative to the mortar. 2 The amount of [amount] is introduced into the third inlet 145. The obtained equipment and bubble distribution are as follows: Figure 4B As shown. Figure 4B The image size is 16.6 mm x 12.5 mm.

[0068] Example 2

[0069] Device 100 was tested again in Example 2, with the second inlet 130 located at the end of channel 110, as follows. Figure 2 As shown. The conditions for Example 2 are basically the same as those for Example 1, except that a reduced amount of PNS is used as a coalescence promoter at 0.09 wt% (6.3 g / m³) relative to the slurry. 2 The amount of PCE introduced into the third inlet 145 was 0.16 wt% (11.5 g / m³) relative to the slurry. 2 The amount of [amount] is introduced into the second inlet 130. The equipment and bubble distribution are as follows: Figure 5A As shown. Figure 5A The image size is 16.6 mm x 12.5 mm.

[0070] Comparative Example 1

[0071] Figure 6 A schematic diagram of device 100' from Comparative Example 1 is depicted. Device 100' and Figure 2 The device 100 is substantially the same, except that the second inlet 130' is located upstream of a pair of first inlets 125a, 125b. Device 100' falls outside the scope of this invention because the second inlet 130' is located upstream of the pair of first inlets 125a, 125b. The second inlet 130' is located in the mixing chamber 105, at the same location as the third inlet 145. PCE is again introduced into the cement slurry through the second inlet 130' as a coalescence inhibitor additive at an amount of 0.16 wt% (11.5 g / m²) relative to the mortar.

[0072] Comparative Example 1 was performed under the same conditions as in Example 2. PNS was again used at 0.09 wt% (6.3 g / m³) relative to the plaster. 2 The quantity of ) is introduced.

[0073] In Comparative Example 1, the coalescence inhibitor was introduced upstream of the location where foam was introduced into the cement slurry. The equipment and bubble distribution are as follows: Figure 5B As shown. Figure 5B The image size is 16.6 mm x 12.5 mm.

[0074] Table 1 shows the bubble size distribution for each test.

[0075] Table 1

[0076]

[0077] from Figure 4A and 4B It can be observed that the introduction of the coalescence inhibitor additive negatively impacts the agglomeration of air bubbles in the cement slurry, and correspondingly reduces the D50 value. However, the D50 value of Example 1 remains within acceptable limits, i.e., it is greater than 200 µm. The initial D50 bubble size of the foam introduced into device 100 is 100 µm.

[0078] It can be understood that the D50 value is the median bubble diameter measured through image analysis of the sample's polished surface, corresponding to the two-dimensional pore size.

[0079] Agglomeration inhibitors can be highly beneficial in improving other properties of cement pastes, such as flowability. Therefore, it is desirable to introduce agglomeration inhibitors into cement pastes and optimize their introduction location to reduce their negative impact on agglomeration.

[0080] When the coalescence inhibitor is introduced downstream of the foam introduction location (i.e., the location of the pair of first inlets 125a, 125b), compared to when the coalescence inhibitor is introduced upstream of the pair of first inlets 125a, 125b, Figure 5A and 5B An improvement in coalescence was observed. Specifically, when the coalescence inhibitor was located upstream of a pair of first inlets 125a, 125b, coalescence was reduced by 31%.

[0081] Despite the reduction in coalescence promoter, the D50 value of Example 2 remained within the acceptable limit of greater than 200 µm. In contrast, the D50 value of Comparative Example 1 was far below the acceptable limit.

[0082] Laboratory testing

[0083] Figure 7 The apparatus for replicating the invention is shown (particularly such as...). Figure 2 The laboratory steps performed under the conditions experienced by the equipment shown are as follows: To replicate the conditions in mixing chamber 105, in a first laboratory step, cementitious materials and water are mixed in a container for 40 seconds using shear blades at a speed of 2750 rpm, as mixing step 301. To replicate the injection of foam into the multiple first inlets 125a, 125b in mixing chamber 105 and channel 115, in foam injection step 302, cementitious materials and water are mixed for 16 seconds using square blades at a speed of 250 rpm. Then, foam is added to the cementitious materials and water in the container to form a cement slurry, and the cement slurry is mixed for 10 seconds using square blades at a speed of 250 rpm.

[0084] To replicate the addition of cement slurry coalescing in channel 115, in coalescing step 303, the cement slurry is mixed for 40 seconds using cylindrical blades at a speed of 500 rpm. The cylindrical blades introduce moderate shear into the cement slurry, replicating the shear forces experienced by the slurry in channel 115.

[0085] To replicate the addition of the coalescence inhibitor through the second inlet 130, in additive addition step 304, the cement slurry is manually mixed for 15 seconds using a smooth blade. The dosage of the unstable soap solution concentration is adjusted to replicate plant conditions in laboratory tests.

[0086] Similarly, Figure 8 The invention illustrates devices that fall outside the scope of this invention (especially such as...). Figure 6 Laboratory procedures performed under the conditions experienced by the equipment shown.

[0087] In the first laboratory step, cementitious materials and water are mixed in a container for 40 seconds at 2750 rpm using a shear blade, as mixing step 301. Following mixing step 301 is additive addition step 304, in which an agglomeration inhibitor additive is introduced into the container. In additive addition step 304, the cement slurry is manually mixed for 15 seconds using a smooth blade.

[0088] This is followed by foam injection step 302 and coalescence step 303. To replicate the injection of foam into the multiple first inlets 125a, 125b in mixing chamber 105 and channel 115, the foam is added to the cementitious material, water, and coalescence inhibitor in the container. In foam injection step 302, the foam, cementitious material, water, and coalescence inhibitor are mixed for 16 seconds at a speed of 250 rpm using a square blade. Then, the foamed cement slurry is mixed for 10 seconds at a speed of 250 rpm using a square blade to homogenize the mixture. To replicate the addition of cement slurry coalescence in channel 115, in coalescence step 303, the cement slurry is mixed for 40 seconds at a speed of 500 rpm using a cylindrical blade.

[0089] In this way, the coalescence inhibitor is introduced before the foam is introduced, replicating the upstream position of the second inlet 130.

[0090] The first test was conducted with polycarboxylic acid (PCE) as a coalescence inhibitor, and the second test was conducted with potassium sulfate (K2SO4) as a coalescence inhibitor.

[0091] In the following laboratory tests, the cement grout included calcium sulfate hemihydrate (mortar). The produced sample weighed 8.5 kg / m³. 2 It has a water content of 66% and an unstable soap solution concentration of 1%.

[0092] The flowability of the cement slurry was assessed by a slump test, with a measured slump of 180–200 mm. The slump test was performed in accordance with methods known in the art, wherein a spreading test was used to evaluate the viscosity of the slurry. The slurry was poured into a ring with a diameter of 5 cm and a height of 10 cm. The ring was then lifted, allowing the slurry to spread under gravity, and the slump was evaluated. The setting time of the cement slurry was tested using the scalpel setting method, which was performed at 6 minutes. The scalpel setting method was performed in accordance with methods known in the art, wherein the scalpel setting method allows for the measurement of the initial setting time of the slurry. The initial setting time corresponds to the time it takes for the slurry to undergo a liquid-to-solid transition.

[0093] The results of the laboratory tests are shown in Figures 9 and 10 and Table 2 below.

[0094] Comparative Example 2

[0095] Using the above Figure 8 Copy the steps Figure 6 Equipment 100' used PCE as a coalescence inhibitor at a dosage of 0.25 wt% relative to the mortar. No coalescence accelerator was added to the cement slurry. The replicated equipment and bubble distribution are as follows: Figure 9A As shown. Figure 9A The image size is 16.9 mm x 12.6 mm.

[0096] Example 3

[0097] Using the above Figure 7 Copy the steps Figure 2 Equipment 100 uses PCE as a coalescence inhibitor at a dosage of 0.25 wt% relative to the mortar. No coalescence accelerator is added to the cement slurry. The replicated equipment and bubble distribution are as follows: Figure 9B As shown. Figure 9B The image size is 16.9 mm x 12.6 mm.

[0098] Comparative Example 3

[0099] Using the above Figure 8 Copy the steps Figure 6 Equipment 100' uses potassium sulfate (K2SO4) as a coalescence inhibitor at a dosage of 0.66 wt% relative to the slurry. Additionally, during the mixing step at 2750 rpm for 40 seconds using shear blades, polynaphthalene sulfonate (PNS) is introduced into the container as a coalescence promoter. The dosage of PNS is 0.4 wt% relative to the slurry. The replicated equipment and bubble distribution are as follows... Figure 10A As shown. Figure 10A The image size is 18.4mm x 13.8mm.

[0100] Example 4

[0101] Using the above Figure 7 Copy the steps Figure 2 Equipment 100 uses potassium sulfate (K2SO4) as a coalescence inhibitor at a dosage of 0.66 wt% relative to the slurry. Additionally, during the mixing step at 2750 rpm for 40 seconds using shear blades, polynaphthalene sulfonate (PNS) is introduced into the container as a coalescence promoter. The dosage of PNS is 0.4 wt% relative to the slurry. The replicated equipment and bubble distribution are as follows... Figure 10B As shown. Figure 10B The image size is 18.4 mm x 13.8 mm.

[0102] Table 2 shows the bubble size distribution for each test.

[0103] Table 2

[0104]

[0105] Comparative Example 2 showed coalescence below the acceptable threshold of at least 200 µm, representing a 37% reduction in coalescence compared to Example 3. This demonstrates that it is advantageous to introduce coalescence inhibitors after (and thus downstream of) the introduction of foam.

[0106] The coalescence in Comparative Example 3 was also below the acceptable threshold. Compared to Example 3, coalescence was reduced by 8%, further demonstrating the advantage of introducing coalescence inhibitors downstream of the foam initiation point.

[0107] Therefore, the advantages of the device 100 of the present invention can be observed. In particular, the advantage of the second inlet 130 for introducing the coalescence inhibitor additive into the cement slurry being located downstream of the plurality of first inlets 125a, 125b is that it is located in the same location.

Claims

1. An apparatus for manufacturing a foamed cement slurry, the apparatus comprising: A mixing chamber used to mix cementitious materials and water to form cement slurry. A channel at one end is fluidly connected to the mixing chamber, the channel being used to receive cement slurry from the mixing chamber. The channel extends from the first end and terminates at at least one second end; The device includes a foam inlet for introducing foam into the mixing chamber or the channel; The device further includes a coalescence inhibitor inlet in the cement slurry downstream of the foam inlet for introducing a coalescence inhibitor additive.

2. The device of claim 1, wherein the at least one second end of the channel is connected to a distribution pipe.

3. The device according to claim 1, wherein the at least one second end of the channel is connected to a secondary chamber.

4. The device according to any of the preceding claims, wherein the coalescence inhibitor inlet is located between the foam inlet and the at least one second end of the channel.

5. The apparatus of claim 3, wherein the coalescence inhibitor inlet is located in the secondary chamber.

6. The device according to any one of the preceding claims, wherein the coalescence inhibitor inlet is a fluid inlet.

7. The apparatus according to any one of the preceding claims, wherein the apparatus further comprises a coalescence accelerator inlet for introducing a coalescence accelerator into the cement slurry.

8. The apparatus of claim 7, wherein the coalescence promoter inlet is located upstream of the coalescence inhibitor inlet.

9. The device according to claim 7 or 8, wherein the coalescence promoter inlet is located downstream of the foam inlet.

10. The apparatus according to any one of claims 7 to 9, wherein the coalescence promoter inlet is located in the channel.

11. The device according to any one of claims 7 to 10, wherein the distance between the coalescence promoter inlet and the foam inlet is less than the distance between the coalescence promoter inlet and the coalescence inhibitor inlet.

12. The apparatus of claim 7, wherein the coalescence promoter inlet is combined with the foam inlet.

13. The apparatus according to any of the preceding claims, wherein the mixing chamber is a tangential mixing chamber.

14. A method for manufacturing a foamed cement slurry, the method comprising: Provide the device as described in any of the preceding claims; Cement materials and water are introduced into the mixing chamber to form a cement slurry; Foam is introduced into the cement slurry through the foam inlet; as well as The coalescence inhibitor is introduced into the cement slurry through the coalescence inhibitor inlet.

15. The method of claim 14, wherein the device includes the coalescence accelerator inlet, and the method includes introducing a coalescence accelerator into the cement slurry through the coalescence accelerator inlet.

Images