JPS6337054B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an alumina cement composition with excellent fire resistance. Conventionally, alumina powder has been added to improve the fire resistance of alumina cement. In this type of refractory alumina cement, the fire resistance improves as the amount of alumina powder increases, but on the other hand, the ratio of hydraulic compounds decreases, resulting in a decrease in the strength of the cured product. Furthermore, when used in castable refractories and the like and heated, there was a drawback that the strength of the hardened alumina cement decreased, especially in the intermediate temperature range (around 1000°C). To prevent this, measures have been taken to increase the activity of the alumina powder added. However, increasing the activity of alumina powder can prevent strength loss to some extent in the intermediate temperature range;
Since the water absorption caused by the active alumina powder increases, the amount of water mixed must be increased in order to improve workability. As a result, the cured product shrinks significantly when heated, resulting in properties that are undesirable as a refractory. Conventional refractory alumina cement is
The drawback was that at least one of the properties of fire resistance, strength, and shrinkage was not satisfied. The present inventors conducted intensive research in search of excellent alumina cement without such drawbacks, and as a result, they found CaO・2Al ₂ O ₃ , 12CaO・7Al ₂ O ₃ , and
An alumina cement composition obtained by adding and mixing a surfactant and a setting retarder to a composition made of CaO・Al ₂ O ₃ or a composition made by adding fine powder alumina to this composition is a substitute for conventional refractory alumina cement. In comparison, the present invention was completed based on the knowledge that the various characteristics of fire resistance, strength, and shrinkage could satisfy the demands of consumers. CaO・2Al ₂ O ₃ is 2 to 92% by weight, 12CaO・
7Al ₂ O ₃ component content in a composition containing 2 to 35% by weight of Al ₂ O ₃ and 1 to 95% by weight of CaO.Al ₂ O ₃ , or in a composition in which finely powdered alumina is added to this composition. The amount
For 100 parts by weight of the blended composition, which is 70-90% by weight,
This is an alumina cement composition prepared by adding and mixing 0.05 to 2.5 parts by weight of a sulfonic acid-based anionic surfactant and 0.1 to 2.5 parts by weight of a setting retarder. CaO・2Al ₂ O ₃ (hereinafter referred to as CA ₂ ) used in the present invention is 2 to 92% by weight, 12CaO・7Al ₂ O ₃ (hereinafter referred to as
The composition contains 2 to 35% by weight of C ₁₂ A ₇ ) and 1 to 95% by weight of CaO.Al ₂ O ₃ (hereinafter referred to as CA), which contains high purity calcareous raw materials (e.g. limestone) and alumina raw materials (e.g. limestone). For example, it can be obtained by blending aluminum hydroxide, aluminum oxide, etc. produced by the Bayer process in a predetermined proportion, and firing or melting this using a conventional firing device (for example, a rotary kiln, a reverberatory furnace, etc.) . In this case, CA ₂ and CA can be produced individually or simultaneously, but when CA is produced by the firing method using a rotary kiln, CA ₂ is 2% by weight.
It is easier to bake if the raw materials are blended as above. A blending composition in which CA ₂ is less than 2% by weight is not preferred because it tends to melt and fuse during firing. Since C ₁₂ A ₇ cannot be produced simultaneously with CA ₂ and CA, it is produced independently in a rotary kiln or reverberatory furnace. When blending CA ₂ , CA and C ₁₂ A ₇ ,
Expressing these three components as percentages, CA ₂ is 2 to 92% by weight, CA is 1 to 95% by weight, and C ₁₂ A ₇ is 2 to 35% by weight.
It is preferable to mix them in such a manner that the weight percentage is as follows. As the fine alumina used in the present invention, one with relatively few impurities, such as aluminum oxide produced by the Bayer process, can be used.
A material having a specific surface area of about 1 to 25 m ² /g is preferable. A blended composition consisting mainly of CA ₂ , CA, C ₁₂ A ₇ or a composition in which finely powdered alumina is added and mixed will result in instant setting, poor strength development, and large shrinkage. So, for this,
Furthermore, it is necessary to add a setting retarder and a sulfonic acid-based anionic surfactant (hereinafter simply referred to as surfactant). As setting retarders, hydroxycarboxylic acids and their salts, such as citric acid, tartaric acid, gluconic acid, salicylic acid and their salts such as sodium, potassium and calcium, or polysaccharides such as sutucarose and sodium alginate and their salts The amount added is 0.1 to 2.5 parts by weight based on 100 parts by weight of the blended composition, and if it is less than 0.1 part by weight, there is no effect of addition, and if it exceeds 2.5 parts by weight, the retardation effect is weak, which is not preferable. Examples of the surfactant include polyalkylaryl sulfonic acids, alkyl sulfonic acids, α-sulfonated fatty acids, and salts thereof, and the amount added is 0.05 parts by weight per 100 parts by weight of the blended composition. If the amount is less than 0.05 part by weight, there is no effect of addition.
If it exceeds 2.5 parts by weight, the strength development effect will be reduced and shrinkage will increase, which is not preferable. The alumina cement composition of the present invention varies depending on the purpose of use, but when used for castable cement, it is preferable that the amount passing through a 44μ sieve is 80% or more. To prepare the alumina cement composition of the present invention, each component forming the product may be individually ground and the resulting individual ground products may be mixed in a predetermined proportion;
Alternatively, a composition in which the individual components are mixed in a predetermined ratio is pulverized, or a plurality of the individual components forming the product are mixed in a predetermined ratio and the remaining components are mixed into the pulverized product. It can be obtained by adding and mixing the individually pulverized products in a predetermined ratio. The alumina cement composition of the present invention not only has a high degree of fire resistance, but also has excellent strength and shrinkage properties, and has extremely good workability. The present invention will be described below with reference to Examples, but the present invention is not limited thereto. All percentages and parts in the text are by weight unless otherwise specified. Example 1 The following experiment was conducted to determine the appropriate mixing ratio of the four components CA ₂ , CA, C ₁₂ A ₇ , and fine powder alumina, or to determine the appropriate chemical composition of alumina cement clinker. Summer. Clinker consisting of CA ₂ and CA is made using high purity limestone (98% purity) and aluminum oxide (purity 98%) as raw materials.
99.6%), and blended these raw materials to obtain the three types of compositions shown in Table 1.
Mix and grind the resulting mixed composition using a rotary kiln.
Obtained by firing at 1500-1600°C. The C ₁₂ A ₇ clinker was obtained by mixing and pulverizing the high-purity limestone and aluminum oxide at a molar ratio of 12:7 and heating and melting the mixture at about 1600° C. using a reverberatory furnace. Table 1 shows the blending ratio of these raw materials and the compound composition of the clinker.

[Table] Fine powder alumina is a product of Mitsui Alumina Manufacturing Co., Ltd.
MA-20 (product name) was used. The BET specific surface area of this fine powder alumina is 10m ² /g
It was hot. As a surfactant, Kao Soap Co., Ltd. contains polyalkylaryl sodium sulfonate as an active ingredient.
Mighty 100 (trade name) manufactured by Manufacturer Co., Ltd., and the reagent sodium citrate was used as the setting retarder. In addition, castable refractories were tested to determine the performance of the alumina cement composition prepared as described below. (product name) was used.The test method was JISR-2553,
2554 compliant. Alumina cement compositions are made by blending clinkers consisting of CA ₂ and CA, and C ₁₂ A ₇ clinkers in various proportions, and adding fine powder alumina to each of the blended compositions _{. The three} components were adjusted to 80%, and then 1.0 part of Mighty 100 and 0.2 parts of sodium citrate were added to 100 parts of each composition, and sieved through a 44 μ sieve to approximately 90%.
It was prepared by mixing and pulverizing it so that it passed through. 20°C for each alumina cement composition obtained.
The strength was measured after curing for 24 hours in a humid atmosphere.
The relationship between CA ₂ content and daily compressive strength was determined, and the results are shown in Figure 1. As a result, it was found that the appropriate ratio is 65-98% of the clinker consisting of CA ₂ and CA, and 2-35% of the C ₁₂ A ₇ clinker. Example 2 Finely powdered alumina was added in various proportions to a mixture of CA ₂ and CA clinker produced in Example 1 and C ₁₂ A ₇ clinker in a ratio of 85:15, and each After adding 1.0 part of Mighty 100 and 0.2 part of sodium citrate to 100 parts of the mixed composition, each was mixed and pulverized so that the amount passing through a 44μ sieve was about 90%. Each of the obtained alumina cement compositions was subjected to a firing compressive strength test at 1000°C to determine the relationship between the total Al ₂ O ₃ content and firing strength, and the results are shown in FIG. As a result, it was found that the preferable range for the total Al ₂ O ₃ content in the alumina cement composition is 70 to 90%. Although it was not possible to illustrate, a clinker made of CA ₂ and CA having the compositions shown in Example 1 and Example 2,
C ₁₂ A ₇ For compositions consisting of clinker and finely divided alumina, do not include surfactants or setting retarders.
When alumina cement compositions were prepared by varying the amount of C ₁₂ A ₇ clinker or the total amount of Al ₂ O ₃ , rapid setting occurred in all of these alumina cement compositions, making it impossible to measure the strength. Example 3 A mixture of 63 parts of limestone and 65 parts of aluminum oxide was calcined according to the method described in Example 1.
Total Al ₂ O ₃ was added to a composition containing a clinker consisting of CA ₂ and CA and a C ₁₂ A ₇ clinker in a ratio of 85:15.
0.2 parts of sodium citrate was added to 100 parts of the mixed composition to which finely powdered alumina was added so that the amount was 80%, and the Mighty 100, which is a surfactant, was added in various proportions to the resulting mixed composition. An alumina cement composition was prepared by mixing and pulverizing the respective formulations added in step 1 so that about 90% of the ingredients passed through a 44μ sieve. A fired compressive strength test was conducted on each alumina cement composition at 1000°C to determine the relationship between the amount of surfactant added and the fired compressive strength, and the results are shown in FIG. Example 4 CA ₂ having the same composition as used in Example 3 and
Sodium citrate was added as a setting retarder to a mixed composition in which 1 part of a surfactant (Mighty 100 manufactured by Kao Soap Co., Ltd.) was added to 100 parts of a mixed composition of CA clinker, C ₁₂ A ₇ clinker, and finely powdered alumina. and adding it in various amounts,
The resulting mixture was ground according to Example 3 to give the same particle size. The setting time of each of the obtained compositions was measured and the relationship between the setting time (starting time) and the amount of sodium citrate added was determined, and the obtained results are shown in FIG. Example 5 CA ₂ having the same composition as used in Example 3 and
A blended composition in which 1 part of Mighty 100 and 0.2 parts of sodium citrate were added to 100 parts of a mixed composition of CA clinker, C ₁₂ A ₇ clinker, and finely powdered alumina was prepared in various ways using a batch-type experimental ball mill. The particle size of each of the obtained pulverized products was mixed and pulverized to determine the proportion of each pulverized product passing through a 44μ sieve, and the curing temperature was 20°C for each pulverized composition.
A compressive strength test was conducted after 24 hours of aging. The relationship between the particle size of the obtained composition and its 24-hour compressive strength is shown in FIG. Examples 6 to 23 To each of the CA ₂ and CA clinkers shown in Table 2, 5, 15, and 30% of C ₁₂ A ₇ clinker was added, and the total
The Mighty 100 and sodium citrate were blended in the proportions shown in Table 2 to 100 parts of each composition in which finely powdered alumina was blended so that the Al ₂ O ₃ content was 80%. An alumina cement composition was prepared by grinding in a batch-type experimental ball mill so that the amount passing through a 44μ sieve was in the range of 90±2%. About the obtained alumina cement composition
A strength test was conducted according to JISR-2553, and the results are shown in Table 2. Example 24 CA ₂ with the same composition as used in Example 19 and
C ₁₂ A ₇ clinker was added in an amount of 15% to the clinker made of CA. The Al ₂ O ₃ content in this composition was 71.5%.
Next, 1 part of a surfactant (Mighty 100) and 0.2 parts of sodium citrate were added to 100 parts of this composition.
% and finely pulverized according to Examples 6 to 23 to prepare an alumina cement composition. The obtained alumina cement composition was subjected to a strength test according to Examples 6 to 23, and the results were Shown in the table. Reference Examples 1-2 Two types of commercially available products with Al ₂ O ₃ content of approximately 80% (a) Manufactured by Denki Kagaku Kogyo Co., Ltd., trade name "High Alumina Cement Super" (Reference Example 1) Chemical composition : Al ₂ O ₃ 80.0%, CaO 18.5%, Additives: Soda carbonate 0.5% Sodium citrate 0.5% Estimated minerals: CA 49.7%, C ₁₂ A ₇ 4.3%, α-
Al ₂ O ₃ 46.0%, C ₁₂ A ₇ /CA=0.09 (b) Manufactured by Alcoa, trade name “Alcoa CA25” (Reference example 2) Chemical composition: Al ₂ O ₃ 79.6%, CaO 18.1%, Estimated mineralogy : CA48.2%, C ₁₂ A ₇ 6.8%, α-
45.0% Al ₂ O ₃ was selected, and strength tests were conducted on these according to Examples 6 to 23, and the results are shown in Table 2. From Table 2, it was determined that the alumina cement composition according to the present invention was significantly superior in strength to commercially available products.

[Table] Example 25 Regarding the sample of Example 13, according to JISR2521,
The setting time and flow value were measured in accordance with JISR-2554, and the line change rate of the castable was measured. In addition, these characteristics were also measured for the commercially available products shown in Table 2, and the two were compared. The results are shown in Table 3. From the results in Table 3, it was confirmed that the present invention had excellent fluidity and a significantly small shrinkage rate.

【table】 [Brief explanation of the drawing]

Figure 1 shows three types of CA ₂ and CA in Example 1.
Add C ₁₂ A ₇ clinker in various _proportions to clinker consisting _of
80%, Figure 2 shows the relationship between the C ₁₂ A ₇ content and the one-day compressive strength of the product obtained, and Figure 2 shows the relationship between the Al ₂ O ₃ content and the fired compressive strength in Example 2. Figure 3 shows the relationship between the amount of surfactant added and the calcination (1000°C) compressive strength in Example 3, and Figure 4 shows the relationship between the amount of sodium citrate added and the setting time in Example 4.
FIG. 5 shows the relationship between particle size and daily compressive strength in Example 5. :Curve for clinker 1 consisting of CA ₂ and CA shown in Table 1, :Curve for CA ₂ shown in Table 1 and
The curve for clinker 2 consisting of CA:
Curves for CA ₂ and clinker 3 made of CA shown in Table 1.

Claims (1)

[Claims] 1 CaO・2Al ₂ O ₃ is 2 to 92% by weight, 12CaO・
7 Total _{Al 2} O ₃ component content in a composition in which Al 2 O 3 is 2 to 35% by weight and CaO・Al ₂ O ₃ is 1 to ₉₅ % by weight, or a composition in which finely powdered alumina is added to this composition is 70
For 100 parts by weight of the formulated composition, which is ~90% by weight,
An alumina cement composition prepared by adding and mixing 0.05 to 2.5 parts by weight of a sulfonic acid-based anionic surfactant and 0.1 to 2.5 parts by weight of a setting retarder.