JPH08198649A - Calcium aluminate, cement composition and prepared unshaped refractory containing the same - Google Patents

Abstract

PURPOSE: To produce a prepared unshaped refractory manifesting high strength, excellent in corrosion resistance and causing no crack in a hardened body due to slaking by incorporating previously a basic component such as MgO in calcium aluminate at the time of producing a cement composition. CONSTITUTION: Starting materials to make CaO, Al2 O3 and MgO are compounded, and the mixture is subjected to heat treatment of melting and/or burning with an electric furnace and rotary kiln, etc., and a product is ground to particles of >=3000cm<2> /g Blaine specific surface area with a grinder such as ball mill and vibrating mill. The calcium aluminate containing magnesia spinels and having a chemical component of 15-30wt.% CaO, 60-75wt.% Al2 O3 and 3-15wt.% MgO is obtained as a product. A cement composition is obtained by using 50-100 pts.wt. this calcium aluminate with alumina powder. The cement composition, a fire resistant aggregate and a hardening regulator at need are compounded, and water is added to the compound to mix, then the mixture is cast into an application mold to cure and dry, and the prepared unshaped refractory is obtained.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to calcium aluminate, a cement composition, and an amorphous refractory material containing the same, particularly good fluidity, appropriate curing time, and high strength development. The present invention relates to a calcium aluminate, which has excellent corrosion resistance and does not cause cracking of a hardened body due to digestion, a cement composition, and an amorphous refractory material containing the same.

The calcium aluminate, the cement composition and the amorphous refractory material containing the same according to the present invention include refractory materials such as blast furnaces, electric furnaces, cement kilns, lime furnaces and incinerators. It can be widely used in the field of civil engineering and construction materials such as lining materials for chemical plants and fireproof boards.
Especially when used in the field of refractories, a great effect can be obtained.

[0003]

2. Description of the Related Art Conventionally, as a cement composition or an amorphous refractory containing the same, an alumina cement, a cement composition containing magnesia and / or zircon, etc., and magnesia which is basic to the alumina cement. Amorphous refractories containing spinel, magnesia, and / or alumina have been proposed (JP-A-60-112676).
JP-A-60-122773, JP-A-60-166273, JP-A-60-260476, and JP-A-5-009.
080 JP, JP 5-009081 JP, JP 4-198064 JP, JP 4-193773 JP, JP 4-182362 JP,
JP 4-243980 A, JP 4-325450 A, JP Sho
61-158872 Publication, Ceramic Data Book 1992 p168
~ 175, and Shinagawa White Brick Company Technical Report No.32 1989 p75 ~ 86
etc). However, since these cement compositions and amorphous refractories containing the same are produced by mixing alumina cement and a basic material such as MgO, the basic material is digested, and the digestion is completely prevented. However, there was a problem that the cured body made of these materials was destroyed. Here, digestion means that a basic component such as MgO is brought into contact with added water at the time of construction, for example, becomes a hydroxide such as Mg (OH) ₂ and expands in volume to form a hardened body. A crack is generated.

In order to prevent the digestion, a basic material to be mixed which has improved digestion resistance has been developed, but the digestion resistance is not sufficient and it has not been practically used at present. Yes (Asahi Kasei / Nippon Kagaku Co., Ltd. Magnesia Technical Report No.3 p22-29 1990, MgO clinker refractory with excellent digestion resistance 1992 p686).

Further, improvement of the digestion resistance of basic materials has been difficult with cement compositions and amorphous refractories obtained by mixing basic materials in the form of powder and / or clinker (Japanese Patent Laid-Open No. 4-204). 357152, JP-A-57-191256, Shinagawa White Brick Company Technical Report No. 428, 1991, p30-43).

Further, it has been proposed to use a mineral composition containing magnesia spinel in calcium aluminate, but the calcium aluminate having the described CaO.6Al ₂ O ₃ as its mineral composition is used as a cement. At this time, there was a problem that it could not be used as a binder for amorphous refractory because it had no hydraulic property, which is the most important function.
(JOURNAL OF MATERIALS SCIENCE LETTERS 11, 1992, p3
15-316).

[0007] The present inventor has conducted diligent research, paying attention to the fact that the digestion of a basic material, which is a problem when constructing a basic amorphous refractory, is due to the presence of the post-mixed free basic material. In producing a cement composition, a clinker mineral, in particular, calcium aluminate which is a hydraulic material, by containing a basic component such as MgO in advance, the finding that the above problems can be solved, the present invention was obtained. Has been completed.

[0008]

[Means for Solving the Problems] That is, the present invention comprises a CaO raw material, an Al ₂ O ₃ raw material, and an MgO raw material, and heat-treating them. The product contains magnesia spinels, and The chemical composition of CaO is 15-30% by weight, Al ₂ O ₃ 60-75% by weight,
And MgO 3 to 15% by weight, which is a calcium aluminate, a cement composition containing the calcium aluminate, and an amorphous form containing the cement composition and a refractory aggregate. It is a refractory material.

The present invention will be described in detail below.

The calcium aluminate used in the present invention is obtained by heat-treating the blended CaO raw material, Al ₂ O ₃ raw material, and MgO raw material. The product contains magnesia spinels and has a specific chemical composition. I have.

As the CaO raw material used in the present invention, limestone, calcium carbonate, quick lime, calcium hydroxide and the like can be used. As the Al ₂ O ₃ raw material, natural alumina raw materials such as shale shale, bauxite, and high alumina chamotte, and purified alumina such as Bayer alumina, fused alumina, and sintered alumina can be used. Further, as the MgO raw material, those containing various MgO can be used, and specifically, magnesium hydroxide extracted from seawater by the seawater method, magnesium carbonate, obtained by firing them in a kiln or the like. Magnesia clinker, light-burning magnesia, electro-melting magnesia clinker obtained by melting magnesia clinker in an electric furnace, natural magnesia mined in China etc., purified magnesia subjected to high purification treatment, vapor phase magnesia, etc. is the purity of the MgO in the MgO raw material, SiO ₂ is not less than 80%
Impurities such as TiO ₂ and TiO ₂ are few and preferred. CaO raw material, Al ₂ O ₃
The particle size of the raw material and the MgO raw material is not particularly limited, but is preferably 30 mm or less and more preferably 5 mm or less from the viewpoint of easy formation of calcium aluminate.

The calcium aluminate of the present invention is
Mix CaO raw material, Al ₂ O ₃ raw material, and MgO raw material,
Manufactured by performing heat treatment for melting and / or firing in a reverberatory furnace, open furnace, converter, rotary kiln, etc., and crushing the product with a crusher such as a ball mill, tube mill, vibration mill, roller mill, or tower mill. it can.

As described above, according to the present invention, any of the heat treatment methods of melting and / or calcining calcium aluminate can be manufactured, but like the electric furnace, reverberatory furnace, high frequency furnace, and plasma melting furnace, It is preferable to manufacture by a melting method capable of completely melting the blended raw materials. In the case of manufacturing by the melting method, the melting temperature is preferably 1,500 ° C. or higher, more preferably 1,600 ° C. or higher, and most preferably 1,800 ° C. or higher in order to completely react the CaO raw material, the Al ₂ O ₃ raw material and the MgO raw material. After tapping the melt according to a normal operating method of an electric furnace or the like, it is cooled to a temperature at which it can be handled by a high-speed air flow, a rotary cooler or the like to obtain a desired product. When melting, CaO, Al ₂ O ₃ , and
Since MgO easily separates in specific gravity in a furnace, it is important to maintain a molten state for a certain period of time, for example, at least about 5 minutes or more after melting to produce a compositionally stable mineral. If the molten state holding time is not sufficient, MgO is not contained in the product as magnesia spinel and tends to be present in the product as free MgO.

The calcium aluminate of the present invention is CaO.
Is C, Al ₂ O ₃ is A, and H ₂ O is H, the mineral composition is CA ₂ , CA, C ₁₂ A ₇ , and C ₁₂ A ₇ H. Contains one or more as a main component. The crystalline form of calcium aluminate is
Either crystalline or amorphous can be used. Further, calcium aluminate is not particularly limited, but when it is made into a cement composition, from the viewpoint of exhibiting excellent fluidity and appropriate curing time, and high strength, those mainly composed of CA are preferable. As impurities, 2CaO ・ Al ₂ O ₃・ S
Although it is possible to use calcium aluminate containing iO ₂ , 4CaO ・ Al ₂ O ₃・ Fe ₂ O ₃ , and CaO ・ TiO _2, etc., CaO and A
Components other than l ₂ O ₃ , for example, impurities such as SiO ₂ , TiO ₂ , Fe ₂ O ₃ , K ₂ O, and Na ₂ O, when used as an amorphous refractory,
The content of these impurities is low because cracks and peeling occur due to shrinkage at high temperatures, the formation of low melting point compounds lowers the fire resistance and softening point under load, and deteriorates properties such as corrosion resistance. Is preferred.

The chemical components of the calcium aluminate of the present invention include CaO 15 to 30% by weight, Al ₂ O ₃ 60 to 75% by weight, and MgO.
It is 3 to 15% by weight, preferably 20 to 25% by weight of CaO, 65 to 70% by weight of Al ₂ O ₃ , and 5 to 10% by weight of MgO. 30% by weight of CaO
If it exceeds, the rapid-hardening mineral composition such as C ₁₂ A ₇ and C ₃ A tends to be generated, the fluidity becomes difficult to obtain, and the pot life becomes short, which is not preferable. On the other hand, if the CaO content is less than 15% by weight, the retardation and strength development tend to decrease, which is not preferable. Further, when MgO exceeds 15% by weight, the amount of calcium aluminate, which is a hydraulic component, decreases, so that strength development tends to decrease, and when MgO is less than 3% by weight, corrosion resistance tends to decrease. There is not preferable.

The magnesia spinel of the present invention means MgO and A
The main mineral is MgO.Al ₂ O ₃ composed of l ₂ O ₃ and the composition ratio of MgO and Al ₂ O _{3 in} the magnesia spinel is Mg
It is preferable that the O content is 20 to 40% by weight and the Al ₂ O ₃ content is 60 to 80% by weight. When magnesia spinel is contained in calcium aluminate, the component ratio of MgO and Al ₂ O _{3 in} the magnesia spinel is more preferably MgO 25 to 35% by weight and Al ₂ O ₃ 65 to 75% by weight. If the MgO content is less than 20% by weight, the corrosion resistance tends to decrease, and if it exceeds 40% by weight, the MgO content when mixed with water
There is a tendency that the cured product swells due to the digestion of, and the fluidity is apt to be deteriorated by Mg ions eluted during mixing with water.

In the present invention, it is important that magnesia spinel is contained in the calcium aluminate produced by the heat treatment. In particular, when the calcium aluminate is analyzed by EPMA or the like, it is preferable that the magnesia spinel is dispersed almost uniformly in the calcium aluminate.

In the present invention, in addition to magnesia spinel, there is no problem if calcium aluminate contains magnesia.

Here, magnesia is MgO, which is preferably contained in the calcium aluminate in the calcium aluminate, and may be partially contained in the magnesia spinel. Further, in the present invention, when magnesia is analyzed by EPMA or the like, it is preferable that magnesia is dispersed almost uniformly in the calcium aluminate. If it is not uniformly dispersed, free MgO is generated in the cement composition, and digestion tends to occur easily.

The vitrification rate of the calcium aluminate of the present invention can be controlled by adjusting the cooling rate after tapping, and if it is forcibly cooled with high pressure air or the like, the vitrification rate tends to increase. The degree of vitrification can be calculated from the peak area of the diffraction line of a specific mineral composition by the powder X-ray diffraction method. In the present invention, the vitrification rate is not particularly limited, but when the vitrification rate of calcium aluminate is high, the hydraulic property becomes strong, and a high-strength cured body can be obtained. preferable. The vitrification rate is preferably 30% or more, and more preferably 50% or more from the viewpoint of obtaining high strength.

With respect to the particle size of the calcium aluminate of the present invention, a finer particle size is preferable because it is excellent in fluidity and strength development, and it is measured by the Blaine method specified in JIS R 2521.
The ratio is preferably at least 3,000 cm ² / g surface area, more preferably at least ^{4,000cm 2 / g, 5,000cm 2 /} g or more is most preferred. The average particle size of calcium aluminate is preferably 20 μm or less, more preferably 5 μm or less. The smaller the average particle diameter is, the higher fluidity can be exhibited when used by kneading with water, and the cured product can be obtained with a low kneading amount of water, so that a dense structure is obtained and the durability is improved, which is preferable. In particular, in order to carry out a uniform hydration reaction with water, it is preferable that the number of particles with a large particle size of more than 90 μm is small, and the hydration reaction proceeds uniformly, and it is easy to control the curing property.
It is more preferable that the number of particles having a particle size exceeding 10 is small.

The calcium aluminate of the present invention can be used as a cement composition by itself or in combination with calcium aluminate and alumina. The compounding amount of calcium aluminate is 5 in 100 parts by weight of the cement composition.
0 to 100 parts by weight is preferable, and 80 to 100 parts by weight is more preferable. If it is less than 50 parts by weight, the strength developability tends to decrease.

As for the particle size of the cement composition of the present invention, the smaller the particle size, the more excellent the fluidity and the strength development.
The specific surface area was measured by the Blaine method specified in 2521.
3,000cm is preferably not less than ² / g, more preferably at least ^{4,000cm 2 / g, 5,000cm 2 /} g or more is most preferred. The average particle size of the cement composition is preferably 20 μm or less, 5 μm
The following is more preferable. The smaller the average particle diameter is, the higher fluidity can be exhibited when used by kneading with water, and the cured product can be obtained with a low kneading amount of water, so that a dense structure is obtained and the durability is improved, which is preferable. In particular, in order to carry out a uniform hydration reaction with water, it is preferable that the number of particles with a large particle size of 90 μm or more is small, and since the hydration reaction proceeds uniformly and it is easy to control the curing property, it exceeds 45 μm. The smaller the particle size, the more preferable.

In the present invention, the morphology of the constituent mineral composition is important in addition to the constituent proportions of the respective chemical components. Particularly, when MgO is M, the mineral composition in calcium aluminate is mainly composed of at least CA and MA. It is preferable that the content of free MgO is small. When free MgO is present, when mixed with water, M
There is a tendency that the cured product expands due to the digestion of gO, and the fluidity is apt to deteriorate due to Mg ions eluted during mixing with water.

The form of the mineral composition of the cement composition of the present invention can be specified by the powder X-ray diffraction method, and the contained mineral composition can be specified by the presence or absence of diffraction lines and the diffraction intensity of each mineral composition. , Or it can be quantified. Whether or not the magnesia spinel is contained in the calcium aluminate can be determined by directly measuring the cross section of the produced calcium aluminate with EPMA, XMA, and ESCA.
By electron microscope observation and polarization microscope observation, etc.
It can be confirmed by observing the element arrangement and concentration at the interfaces of O, CaO, and Al ₂ O ₃ . The cement composition that has already been crushed utilizes the difference in the true specific gravities of the minerals of calcium aluminate and magnesia spinel, and the crushed product is gravity-separated by a centrifuge, and X-ray diffraction analysis of each separation layer is performed. It is possible to discriminate and determine whether MgO was contained in the calcium aluminate or whether it was post-added to the calcium aluminate material by performing a chemical composition analysis or a chemical component analysis. If magnesia spinel was contained in calcium aluminate, it cannot be separated by specific gravity,
If magnesia spinel or magnesia is added later, it is possible to separate and identify by the difference in specific gravity. In the present invention, it is necessary that the magnesia spinel be contained in the calcium aluminate in advance, and the inclusion of the magnesia spinel improves the digestion resistance and corrosion resistance when blended in the amorphous refractory. is there.

In the present invention, in order to further improve high fire resistance and corrosion resistance, alumina is mixed and pulverized when pulverizing calcium aluminate, and it is usually used in an alumina cement composition for adjusting fluidity and hardenability. Has been
It is possible to add a curing modifier such as a dispersant, a curing accelerator, and a curing retarder.

The hardening modifier is a dispersant, a hardening accelerator, a hardening retarder or the like having a function of improving properties such as fluidity, pot life, hardening time and strength development of cement.

Here, as the dispersant, melamines,
Polycarboxylic acids, condensates of formaldehyde, and a mixture of water-soluble polyacrylic acid or a salt thereof and an alkali metal carbonate, hydroxycarboxylic acid or a salt thereof,
Mixtures of water-soluble polymethacrylic acid and alkali metal carbonates, methacrylic acid-acrylic acid copolymers or mixtures of these salts and alkali metal carbonates, and one selected from hydroxycarboxylic acids or salts thereof or Two or more types can be used.

As the curing accelerator, lithium carbonate, calcium hydroxide, magnesium hydroxide or the like can be used. Further, as the curing retarder, sugars, carboxylic acids, phosphoric acids, boric acids, etc., mixtures of hydroxycarboxylic acids and inorganic carbonates, gluconic acid, citric acid, tartaric acid, and sulfonic acid anionic surfactants, etc.
In addition, a cement admixture made of citric acid and boric acid can be used.

The cement composition of the present invention has good fluidity, appropriate curing time, and high strength development property, and is excellent in erosion resistance, which is a problem of the conventional cement composition. It is a cement composition that does not have the problem of digestion of the hardened material, and can be used in the same manner as alumina cement that is blended with ordinary amorphous refractories.

As the refractory aggregate used in the present invention, alumina aggregates such as sintered alumina, fused alumina and easily sinterable alumina, which are generally used as aggregates of unshaped refractory, and fused alumina Magnesia-based aggregates such as magnesia, sintered magnesia, light-burned magnesia, natural magnesia, magnesia spinel, and magnesite, as well as zircon, zirconia, fused silica, silicon carbide, silicon nitride, silicon nitride iron, boron carbide, and loach , And chamotte, etc., which are usually used for irregularly shaped refractories, and further, graphite synthesized by a method of surface modification of new particles such as air flow impact method,
Silicon carbide, silicon nitride, boride and the like can be used. The refractory aggregate to be combined with the cement composition of the present invention should be appropriately set according to the required characteristics of the irregular refractory, but in the iron-related irregular refractory,
It is preferable to combine, if necessary, an alumina-based aggregate, a magnesia-based aggregate, and a carbon-based aggregate such as natural graphite, artificial graphite, carbon black, and mitch or pellets thereof.

In the present invention, the use of a refractory aggregate containing a basic component such as magnesia or magnesia spinel from the viewpoint of improving the corrosion resistance when blended into an irregular shaped refractory will improve the characteristics of the cement composition of the present invention. It is preferable because it can be sufficiently exhibited.

The cement composition of the present invention is mixed with the refractory aggregate and a curing modifier to be blended if necessary, and then water is added and mixed by a kneader such as a mixer to obtain a desired construction site. Alternatively, it can be poured into a construction mold, cured, and then dried and used at high temperature.

In addition, it is possible to blend ultrafine powder such as silica fume or aerosil, or an explosion-proofing material into this cement composition or amorphous refractory material depending on the required characteristics.

Further, the method of using the cement composition of the present invention is not particularly limited to the pouring method, and a spraying method, a patching method, a stamping method, and a method in which a refractory binder such as ordinary alumina cement is used. It is possible to deal with various construction methods such as the Koteuri method.

[0036]

EXAMPLES The present invention will be described in detail below with reference to examples.

Example 1 Quick lime as a CaO raw material, alumina as an Al ₂ O ₃ raw material, and
Magnesia was mixed as a MgO raw material as shown in Table 1,
After high-temperature melting at 1,750 to 1,900 ° C in an electric furnace, the melt was tapped in a ladle and allowed to cool to produce calcium aluminate. Further, the obtained calcium aluminate was roughly crushed to 5 mm or less with a jaw crusher and crushed with a batch type ball mill to obtain a cement composition. The particle size of this cement composition was measured by the Blaine method described in JIS R 2521. The results are shown in Table 1. According to the method described in JIS R 2521, the obtained cement composition, Toyoura standard sand, and water were kneaded in a thermostatic chamber at 20 ° C. for 3 minutes, and the physical properties of the obtained mortar were measured.

<Materials used> CaO raw material: quick lime, quick lime manufactured by Denki Kagaku Kogyo KK, 5 to 10 m
m, CaO 98% Al ₂ O ₃ raw material: alumina, Bayer alumina manufactured by Nippon Light Metal Industry Co., Ltd., product name “NMA 10”, Al ₂ O ₃ 99% MgO raw material: magnesia, Ube Chemical Industry magnesia clinker, MgO 96%

<Measurement method of physical properties> Particle size: Blaine specific surface area is measured according to the method described in JIS R 2521. Flow value: Flowability is evaluated, and the mortar after kneading is allowed to stand for a predetermined time, then 30 The spread diameter of the product that has been kneaded for 2 seconds is measured according to JIS R 2521. Curing time: Transfer the mortar after kneading to a heat insulation container,
Measure the heat generated by hydration with a thermometer and measure the time required from the water injection until the heat generation temperature reaches its maximum. Compressive strength: The mortar after kneading is packed in a mold of 40 × 40 × 160 mm, and the compressive strength of the cured product after 24 hours is measured with a pressure-type compressive strength measuring machine to obtain the compressive strength after curing for 24 hours. The cured product after the lapse of time was placed in a drier at 110 ° C., dried for 20 hours, allowed to cool to room temperature, and similarly measured to obtain the compressive strength after drying. Digestion resistance: The mortar after kneading is packed in a 40 × 40 × 160 mm mold, and after 24 hours, the cured product is placed in a 110 ° C. dryer and placed in a steam curing box containing 150 ° C. steam. twenty four
After leaving for a time, the presence or absence of cracks, the presence or absence of bending, and the expansion rate were evaluated. The occurrence of cracks and the degree of bending are visually evaluated, and the expansion rate is measured with a micrometer by measuring the change in length before and after steam curing.

[0040]

[Table 1]

As is clear from Table 1, the cement composition of the present invention has excellent hydraulic properties, fluidity, strength development, and digestion resistance by incorporating a basic component in calcium aluminate in advance. Have.

Example 2 Example 2 was carried out in the same manner as in Example 1 except that the ingredients were compounded as shown in Table 2. The results are also shown in Table 2. In the comparative example, a conventional alumina cement clinker was mixed and crushed with magnesia spinel so as to have the same MgO content in the cement composition. The results are also shown in Table 2.

<Materials used> Alumina cement clinker: equivalent to CaO 34%, Al ₂ O ₃ 65% Magnesia spinel: Omura Fire Resistant Synthetic Spinel, trade name “MS-100”

[0044]

[Table 2]

As is clear from Table 2, the cement composition of the present invention has excellent hydraulic properties, fluidity, strength development, and digestion resistance by incorporating a basic component in calcium aluminate in advance. Have. In particular, the digestion resistance is remarkably improved as compared with the comparative example in which the basic aggregate component is post-added to the alumina cement clinker, and the strength development is also improved.

Example 3 10 parts by weight of the cement composition produced in Examples 1 and 2, 50 parts by weight of fire-resistant aggregate A, 15 parts by weight of fire-resistant aggregate B, and fire-resistant aggregate C
After mixing 25 parts by weight, the mixture was kneaded in a mortar mixer for 1 minute in a thermostatic chamber at 20 ° C according to the method described in JIS R 2553, and then water
The physical properties of the amorphous refractory obtained by adding 10 parts by weight and kneading for 3 minutes were measured. The results are shown in Table 3.

<Materials used> Fireproof aggregate A: trade name “Sintered Alumina SRW” manufactured by Showa Denko KK,
Weight ratio of 5 to 3 mm product / 3 to 1 mm product / 1 to 0 mm product 2/2 /
Mixture of 1 refractory aggregate B: trade name "Fused Alumina RW92" manufactured by Showa Denko KK,
A mixture of 220Mesh F product / 325Mesh F product in a weight ratio of 2/1 Fireproof aggregate C: product name "Sintered Spinel SPL-" manufactured by Shin Nippon Chemical Co., Ltd.
S ", 1-0mm product / Showa Denko" Electric fused alumina RW92 "200Mes
h F mixture of 3/2 weight ratio

<Measurement method> Corrosion resistance: Mortar after kneading was packed in a mold of 40 × 40 × 160 mm, and the cured product after 24 hours was dried in a dryer at 110 ° C., and then at 400 ° C. for 2 hours. Drying, firing at 1,000 ° C in a silicon knit electric furnace for hours, letting the hardened body to cool to room temperature is immersed in high-temperature slag melted in a high-frequency furnace for 10 minutes, and visually confirms the erosion state and the occurrence of cracks. Then, the immersion test piece was cut with a diamond cutter, and the erosion state of the slag inside the hardened body was analyzed by EPMA. The slag infiltration thickness by this EPMA was defined as the erosion depth.

[0049]

[Table 3]

As is clear from Table 3, the amorphous refractory containing the cement composition of the present invention has excellent hydraulic properties, fluidity, strength development and digestion resistance. In particular, the digestion resistance is significantly improved compared to the comparative example in which the basic aggregate component is post-added to the alumina cement clinker, the length change is small, high temperature strength development and slag erosion resistance are also significantly improved. are doing.

[0051]

As is apparent from the above examples, the cement composition of the present invention or the amorphous refractory material containing the cement composition is
There is no problem of digestion of basic materials such as magnesia and spinel that are blended as aggregates in the production of amorphous refractory, which has been a problem in the past, and it has extremely good digestion resistance and corrosion resistance to slag, etc. When blended with, it is possible to obtain high fluidity, appropriate curing time, and high strength development. When the cement composition or amorphous refractory of the present invention is used, in the conventional one, in terms of digestibility, durability, and strength development, it was difficult to construct MgO-C-based or MgO-Cr-based, etc. Not only is it possible to make the basic bricks into an indefinite shape, but it also has the effect of significantly improving the durability of the site where slag erosion is severe. Further, the cement composition of the present invention or an amorphous refractory containing the same, blast furnaces, electric furnaces, cement kilns, lime furnaces, incinerators and other refractory materials field, including lining materials for chemical plants and It can be widely used in the field of civil engineering and construction materials such as fireproof boards. Especially when used in the field of refractories, a great effect can be obtained.

Claims (3)

[Claims] 1. A CaO raw material, an Al ₂ O ₃ raw material, and an MgO raw material are blended and heat-treated, the product contains magnesia spinels, and the chemical component in the product is 15 to 30% by weight of CaO. A
l ₂ O ₃ 60-75% by weight, and MgO 3-15% by weight, calcium aluminate. 2. A cement composition containing the calcium aluminate according to claim 1. 3. An amorphous refractory containing the cement composition according to claim 2 and a refractory aggregate.