Casting material
A pourable refractory material using silica fume, reactive alumina, specific calcium aluminate, and aluminum lactate forms microsilica gel bonds, addressing the cleaning and drying process challenges of existing materials, resulting in efficient construction without downtime and improved structural integrity.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- KROSAKI HARIMA CORP
- Filing Date
- 2025-07-09
- Publication Date
- 2026-05-07
AI Technical Summary
Existing pourable refractory materials using colloidal silica as a binder require thorough cleaning of mixing equipment and increased workload due to the dual role of colloidal silica as both a binder and mixing liquid, and they still necessitate a drying process after application, which incurs costs and downtime.
A pourable material formulation comprising refractory materials with silica fume, reactive alumina, specific calcium aluminate, and aluminum lactate, which forms microsilica gel bonds without the need for a drying process by incorporating these components in specific ratios, allowing for reduced workload and eliminating the drying requirement.
The material achieves reduced construction workload and eliminates the need for a drying process, ensuring stable curing and improved resistance to spalling and corrosion, thereby enhancing construction efficiency and safety.
Smart Images
Figure JPOXMLDOC01-APPB-T000001 
Figure JPOXMLDOC01-APPB-T000002 
Figure JPOXMLDOC01-APPB-T000003
Abstract
Description
pouring material
[0001] The present invention relates to a pouring material used, for example, in blast furnace troughs, molten iron pretreatment equipment (KR) impellers, ladle covers, tundish covers, heating furnace skid pipes, various kilns, incinerators, fluidized bed furnaces, industrial waste kiln treatment furnaces, furnaces for circulating fluidized bed (CFB) boilers, furnaces for cement manufacturing equipment, gasification melting furnaces, stoker furnaces, and the like.
[0002] Castable refractories are a general term for amorphous refractory materials that can be poured into a structure, and are also called castable refractories or castable materials. Commonly used castable materials utilize cement (alumina cement, Portland cement, magnesia cement, etc.) as a binder. However, when cement is used as a binder, a hydration reaction occurs at room temperature, making the matrix of the poured structure dense and difficult to dewater. This creates a risk of spalling if the temperature of the structure rises. Therefore, a drying process is required after pouring, which incurs costs and requires long periods of downtime.
[0003] On the other hand, pourable materials using silica sol, or colloidal silica, as a binder are also known. For example, Patent Document 1 discloses a pourable material for a firing furnace that, by using colloidal silica as a binder, eliminates the need for a drying process after pouring, suppresses physical impact from materials inside the furnace, and suppresses alkali attack.
[0004] In the application of pourable materials, water is typically used as the mixing liquid during the mixing stage. Many mixing mixers are equipped with a water meter and a water tank. However, colloidal silica used in pourable materials serves not only as a binder but also as a mixing liquid. Therefore, when using colloidal silica as a mixing liquid, if the water meter and water tank installed in the mixing mixer are used, thorough cleaning is required after application, resulting in significant time and effort. In contrast, if the water meter and water tank installed in the mixing mixer are not used, the tank containing the colloidal silica must be transported to the construction site, such as a steel mill. Afterward, the required amount of colloidal silica is measured using a beaker or similar device and then added to the mixing mixer containing the refractory materials. Thus, using colloidal silica in pourable materials presents a problem of increased workload compared to using water.
[0005] On the other hand, Non-Patent Document 1 discloses a cementless castable that forms a microsilica gel bond. Microsilica gel bonds can be obtained by mixing refractory materials such as silica fume with water as the mixing liquid. Here, Non-Patent Document 1 discloses a cementless castable, but even though it is called "cementless," it does not mean that it contains absolutely no cement. In other words, ASTM C401-91 classifies castables into four categories based on the CaO content: general castable, low-cement castable, very low-cement castable, and cementless castable. Of these, cementless castable is defined as having a CaO content of 0.2% by mass or less. In this respect, the cementless castable disclosed in Non-Patent Document 1 is 70% CAC (70% by mass Al ２ O ３ - 0.5% by mass of calcium aluminate cement (30% by mass CaO) is added, and the CaO content is approximately 0.5 × 0.3 = 0.15% by mass, which belongs to the category of no-cement castable. Thus, the no-cement castable disclosed in Non-Patent Document 1 contains a CaO component, and Ca in solution ２＋The elution of (and / or other polyvalent cations) causes gelation on the surface of negatively charged microsilica (silica fume). Microsilica bond is a state in which linked microsilica particles form a three-dimensional network due to this gelation. Pouring materials that utilize the formation of microsilica bond in this way can be applied using only water as the liquid, without the need for special liquids such as colloidal silica, thus reducing the workload during application.
[0006] Patent No. 7510557
[0007] “Effect of Additives and Installation Temperatures on Setting Behavior and Mechanical Properties of Self-flowing Silica Bonded No-cement Castables”, ALUMINIUM 2016 11th Trade Fair & Conference, p.75-79
[0008] As described above, pourable materials that utilize the formation of microsilica gel bonds can reduce the workload during construction. However, they have not yet achieved the property of eliminating the need for a drying process, as is the case with pourable materials using colloidal silica. Therefore, the problem that this invention aims to solve is to provide a pourable material that can reduce the workload during construction and eliminate the need for a drying process.
[0009] The inventors conducted extensive testing and research to obtain a pourable material that eliminates the need for a drying process in the formation of microsilica gel bonds, and as a result, they found that the addition of aluminum lactate is effective. Specifically, they found that when one or more types of calcium aluminate selected from CA, CA2, and C12A7 are added in a specific range of addition rates to a refractory raw material formulation containing reactive alumina, a refractory raw material that hardens through a rehydration reaction when silica fume and water are added for the formation of microsilica gel bonds, and aluminum lactate is added in a specific range of addition rates, the aluminum lactate gels with the mixing water during application, and then shrinks in volume during the drying process, causing numerous fine cracks to form in the applied material. These cracks serve as escape routes for water vapor, greatly increasing the dewatering rate, and as a result, the property of eliminating the need for a drying process can be obtained.
[0010] In other words, according to one aspect of the present invention, the following pourable material is provided: A pourable material comprising 100% by mass of a refractory material mixture containing 0.2 to 12% by mass of silica fume, 0.1 to 2% by mass of reactive alumina, which is a refractory material that hardens upon the addition of water, with the remainder being other refractory materials, to which a total of 0.05 to 1% by mass of one or more types of calcium aluminate selected from CA, CA2, and C12A7, and 0.1 to 1.2% by mass of aluminum lactate are added.
[0011] The amorphous pourable material of the present invention reduces the workload during construction and eliminates the need for drying.
[0012] The pourable material of the present invention is prepared by adding 0.05 to 1% by mass of one or more calcium aluminates selected from CA, CA2, and C12A7, and 0.1 to 1.2% by mass of aluminum lactate to 100% by mass of a refractory material mixture containing 0.2 to 12% by mass of silica fume, 0.1 to 2% by mass of reactive alumina, which is a refractory material that hardens when water is added, and the remainder being other refractory materials. In the following description, reactive alumina, which is a refractory material that hardens when water is added, will simply be referred to as "reactive alumina," and one or more calcium aluminates selected from CA, CA2, and C12A7 will be referred to as "specific calcium aluminate." In the present invention, silica fume and reactive alumina in the refractory raw material formulation, as well as specific calcium aluminate added to the refractory raw material formulation, primarily serve as microsilica gel bond-forming materials for forming microsilica gel bonds. That is, as described above, the technical feature of the present invention is that, in order to form microsilica gel bonds, a refractory raw material formulation containing silica fume and reactive alumina in specific ranges, a specific calcium aluminate is added in a specific range of addition rates, and aluminum lactate is added in a specific range of addition rates, thereby providing the property of eliminating the need for a drying process. A detailed explanation follows below.
[0013] The silica fume content is 0.2 to 12% by mass. If the silica fume content is less than 0.2% by mass, the microsilica gel bond will not be sufficiently formed, resulting in insufficient strength after curing (hereinafter referred to as "curing strength"). On the other hand, if the silica fume content exceeds 12% by mass, the matrix of the poured construction becomes excessively dense, making dewatering difficult, and there is a risk of spalling if the temperature of the construction rises. In other words, the spalling resistance decreases, and the property of not requiring a drying process cannot be obtained. The silica fume content is preferably 0.5 to 12% by mass. As the silica fume, those commonly used in pouring materials can be used.
[0014] The reactive alumina content is 0.1 to 2% by mass. If the reactive alumina content is less than 0.1% by mass, the microsilica gel bond will not be sufficiently formed, resulting in insufficient curing strength. On the other hand, if the reactive alumina content exceeds 2% by mass, the matrix of the poured construction becomes excessively dense, reducing the permeability, and as a result, the property of not requiring a drying process cannot be obtained. The reactive alumina content is preferably 0.5 to 1.5% by mass. Here, reactive alumina refers to a refractory raw material that undergoes a rehydration reaction and hardens when water is added, and ρ alumina is a typical example. Reactive alumina is an ultrafine powder with an average particle size (D50) of less than 10 μm, but it is clearly distinguished from alumina ultrafine powders such as activated alumina that are commonly used as refractory raw materials from the viewpoint of reactivity with water. In addition, reactive alumina is generally amorphous and can be distinguished from ordinary alumina ultrafine powders such as activated alumina from the viewpoint of crystal structure.
[0015] Thus, in the present invention, the refractory raw material formulation contains silica fume and reactive alumina as part of the microsilica gel bond-forming material, with the remainder consisting of other refractory raw materials. These other refractory raw materials are those other than silica fume and reactive alumina. As these other refractory raw materials, commonly used refractory raw materials for pourable materials can be used, such as alumina raw materials, magnesia raw materials, spinel raw materials, silica raw materials, carbon raw materials, alumina-silica raw materials, and silicon carbide raw materials. Furthermore, the particle size distribution of these other refractory raw materials can be the same as that of refractory raw materials commonly used in pourable materials.
[0016] The addition rate of the specific calcium aluminate is 0.05 to 1% by mass. When the addition rate of the specific calcium aluminate is less than 0.05% by mass, the microsilica gel bond is not sufficiently formed and the curing strength is insufficient. On the other hand, when the addition rate of the specific calcium aluminate exceeds 1% by mass, the hydration reaction occurs at room temperature and the matrix of the poured construction body becomes dense, making dehydration difficult, and there is a risk of explosion when the temperature of the construction body rises. That is, the explosion resistance decreases and the property of eliminating the drying process cannot be obtained. The addition rate of the specific calcium aluminate is preferably 0.1 to 0.6% by mass. Here, as described above, the specific calcium aluminate is one or more calcium aluminates selected from CA (CaO·Al ２ O ３ ), CA2 (CaO·2Al ２ O ３ ), and C12A7 (12CaO·7Al ２ O ３ ), and is widely known as a main hydraulic mineral constituting alumina cement, which is a typical binder for the poured material. Therefore, in the present invention, the specific calcium aluminate can be added as alumina cement. In this case, the addition rate of the specific calcium aluminate can be calculated based on the addition rate of the alumina cement and the content of the specific calcium aluminate in this alumina cement. On the other hand, the specific calcium aluminate can also be added alone as a mineral or in combination with alumina cement.
[0017] The addition rate of aluminum lactate is 0.1 to 1.2% by mass relative to 100% by mass of the refractory raw material composition. If the addition rate of aluminum lactate is less than 0.1% by mass, the number of fine cracks generated is small, so the effect of improving explosion resistance cannot be sufficiently obtained, and the property of not requiring a drying process cannot be obtained. On the other hand, if the aluminum lactate content exceeds 1.2% by mass, fine cracks are generated excessively, increasing the porosity and thus reducing corrosion resistance. The addition rate of aluminum lactate is preferably 0.3 to 0.8% by mass. Here, aluminum lactate refers to additives such as basic aluminum lactate, modified basic aluminum lactate, and basic lactate-hydroxyaluminum acetate, which are commonly used in amorphous refractories.
[0018] In the present invention, in addition to specific calcium aluminate (alumina cement) and aluminum lactate, various additives such as explosive inhibitors and dispersants may be appropriately added to the refractory raw material formulation. Specific examples of explosive inhibitors include organic fibers, organic blowing agents, and metallic aluminum. Specific examples of organic fibers include high-molecular-weight organic fibers such as vinylon (containing polyvinyl alcohol), rayon, polyester, nylon, polypropylene, and polyethylene. Dispersants provide fluidity during the application of refractory materials, and specific examples include inorganic salts such as sodium tripolyphosphate, sodium hexametaphosphate, ultrapolysodium phosphate, acidic sodium hexametaphosphate, sodium borate, sodium carbonate, and polymetaphosphate, as well as sodium citrate, sodium tartrate, sodium polyacrylate, sodium sulfonate, polycarboxylate, β-naphthalene sulfonates, and naphthalene sulfonic acid. These additives are added to 100% by mass of the refractory raw material formulation, similar to specific calcium aluminate (alumina cement) and aluminum lactate. The addition rate can be the same as that of a typical pouring material.
[0019] Furthermore, in addition to the above-mentioned refractory raw material mixture, as well as specific calcium aluminate (alumina cement), aluminum lactate, and various additives, the pourable material of the present invention may also use coarse grains with a particle size of 8 mm or more. These coarse grains play a role in preventing the propagation of cracks that occur in the matrix of the pourable construction.
[0020] In this invention, the particle size of the refractory material refers to the size of the sieve opening when the refractory material is separated by sieving. For example, a refractory material with a particle size of less than 8 mm is a refractory material that passes through a sieve with an 8 mm opening, and a refractory material with a particle size of 8 mm or more is a refractory material that does not pass through a sieve with an 8 mm opening.
[0021] Tables 1 to 4 show the raw material formulations and evaluation results for the examples and comparative examples of the present invention. In each example shown in Tables 1 to 3, the specific calcium aluminate was added as alumina cement. The addition rates of the specific calcium aluminate shown in Tables 1 to 3 were calculated based on the addition rate of alumina cement and the content of the specific calcium aluminate in this alumina cement, as described above. On the other hand, in each example shown in Table 4, the specific calcium aluminate was added as a mineral alone. The evaluation items and evaluation methods for the pourable materials in each example shown in Tables 1 to 4 are as follows.
[0022] <Curing Strength (Bending Strength After Curing)> Approximately 5% by mass of construction water was added to the pouring material of each example and mixed. The mixture was poured into a mold, cured at 20°C for 24 hours, and the mold was removed. The bending strength of the test specimens obtained was measured in accordance with JIS R 2553. The curing strength was evaluated in three stages: ○ (Excellent) if it was 0.5 MPa or higher, △ (Good) if it was 0.2 MPa or higher and less than 0.5 MPa, and × (Poor) if it was less than 0.2 MPa. ○ (Excellent) or △ (Good) was considered a pass. If this curing strength evaluation is passed, the mold can be removed stably during actual construction without the construction body collapsing or other problems occurring.
[0023] <Apparent Porosity> Approximately 5% by mass of construction water was added to the pourable material of each example and mixed. The mixture was poured into a mold, cured at 20°C for 24 hours, removed from the mold, and then dried at 110°C for 24 hours. The apparent porosity was measured in accordance with JIS R 2205 using the obtained test specimens. The apparent porosity was evaluated in three stages: less than 15% was marked ○ (Excellent), 15% or more but less than 20% was marked △ (Good), and 20% or more was marked × (Poor). ○ (Excellent) or △ (Good) was considered a pass. If the apparent porosity evaluation is satisfactory, a dense structure is obtained and a construction body with excellent corrosion resistance can be obtained.
[0024] <Air permeability> Approximately 5% by mass of construction water was added to the pouring material for each example and mixed. The mixture was poured into a mold, cured at 20°C for 24 hours, removed from the mold, and then dried at 110°C for 24 hours. The air permeability was measured in accordance with JIS R 2115 using the resulting test specimens. The air permeability was 1.0 × 10⁻⁶. －１４ I understand ２ The above scores are marked with ○ (Excellent), 1.0 x 10 －１６ I understand ２ The above 1.0 x 10 －１４ If less than 10, it is marked with △ (Good), 1.0 × 10 －１６ I understand ２ A score below a certain level was marked as × (Poor), and a score of ○ (Excellent) or △ (Good) was considered a passing grade.
[0025] <Splash Resistance> Approximately 5% by mass of construction water was added to each example of the pourable material and mixed. The mixture was poured into a cylindrical mold measuring 100 mmφ × 100 mmh, cured at 20°C for 24 hours, and the mold was removed. Two cylindrical test pieces were then placed in an electric furnace at 900°C and heated for 30 minutes. After removing each test piece, the presence or absence of spalling and crack formation was examined to evaluate the spall resistance. Spall resistance was evaluated on a three-point scale: ○ (Excellent) if there were no cracks or only microcracks, △ (Good) if partial fracture occurred on the surface, and × (Poor) if fracture or more of damage occurred. ○ (Excellent) or △ (Good) was considered a pass. If both this spall resistance evaluation and the above-mentioned air permeability evaluation pass, the drying process after pouring can be eliminated.
[0026] <Overall Evaluation> In the overall evaluation, if all evaluation results are ○, it is ◎ (Excellent); if at least one evaluation result is △ and there are no × evaluation results, it is ○ (Good); and if at least one evaluation result is ×, it is × (Poor). ◎ (Excellent) or ○ (Good) is considered a passing grade.
[0027]
[0028]
[0029]
[0030]
[0031] Tables 1 and 2 show examples in which alumina was used as another refractory material. Of these, the pourable materials of Examples 1 to 12, which are embodiments of the present invention, passed all evaluations of curing strength, apparent porosity, permeability, and explosion resistance, and also passed the overall evaluation. Specifically, Examples 1 to 4 are examples in which the silica fume content was varied. All were within the scope of the present invention and passed all evaluations. In contrast, Comparative Example 1 was an example that did not contain silica fume, and sufficient curing strength could not be obtained. On the other hand, Comparative Example 2 was an example in which the silica fume content exceeded the upper limit of the present invention, and explosion resistance decreased. Examples 5 to 6, 3, and 7 to 8 are examples in which the reactive alumina content was varied. All were within the scope of the present invention, and passed all evaluations. In contrast, Comparative Example 3 was an example that did not contain reactive alumina, and sufficient curing strength could not be obtained. On the other hand, Comparative Example 4 was an example in which the reactive alumina content exceeded the upper limit of the present invention, and permeability decreased. Examples 9-10, 3, and 11-12 are examples in which the addition rate of specific calcium aluminate was varied. All were within the scope of the present invention, and all evaluations were satisfactory. In contrast, Comparative Example 5 was an example in which specific calcium aluminate (alumina cement) was not added, and sufficient curing strength was not obtained. On the other hand, Comparative Example 6 was an example in which the addition rate of specific calcium aluminate exceeded the upper limit of the present invention, and the air permeability and explosive resistance decreased. Examples 13-14, 3, and 15-16 are examples in which the addition rate of aluminum lactate was varied. All were within the scope of the present invention, and all evaluations were satisfactory. In contrast, Comparative Example 7 was an example in which aluminum lactate was not added, and the air permeability and explosive resistance decreased. On the other hand, Comparative Example 8 was an example in which the addition rate of aluminum lactate exceeded the upper limit of the present invention, resulting in high apparent porosity and insufficient curing strength.
[0032] The examples shown in Table 3 are variations in the raw material composition of other refractory materials. All are within the scope of the present invention, and all evaluations were satisfactory. The examples shown in Table 4 are examples in which specific calcium aluminate was added as a mineral alone. All are within the scope of the present invention, and all evaluations were satisfactory.
[0033] Of the above Examples 1 to 29, Examples 2, 3, 4, 6, 7, 10, 11, 14, 15, and 17-25, in which the respective content ratios of silica fume and reactive alumina, as well as the respective addition ratios of specific calcium aluminate and aluminum lactate, were all within a favorable range, received an overall evaluation of ◎ (Excellent), and particularly outstanding properties were obtained.
Claims
1. A pourable material comprising 100% by mass of a refractory material mixture containing 0.2 to 12% by mass of silica fume, 0.1 to 2% by mass of reactive alumina, a refractory material that hardens upon the addition of water, with the remainder being other refractory materials, to which a total of 0.05 to 1% by mass of one or more types of calcium aluminate selected from CA, CA2, and C12A7, and 0.1 to 1.2% by mass of aluminum lactate are added.
2. The pourable material according to claim 1, wherein, in proportion to 100% by mass of the refractory raw material formulation, the silica fume content is 0.5 to 12% by mass, the reactive alumina content, which is a refractory raw material that undergoes a rehydration reaction and hardens when water is added, is 0.2 to 1.5% by mass, and in proportion to 100% by mass of the refractory raw material formulation, the total addition rate of one or more calcium aluminates selected from CA, CA2, and C12A7 is 0.1 to 0.6% by mass, and the addition rate of aluminum lactate is 0.3 to 0.8% by mass.