JP3340298B2 - Alumina cement and amorphous refractories using it - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alumina cement and an amorphous refractory using the same, and more particularly to an alumina cement having a high-temperature sintering property and a high strength developing property and an amorphous refractory using the same. About things. Alumina cement of the present invention and amorphous refractories using the same, mainly in the field of refractories alumina cement is used, ceramic materials, lining of chemical plants, corrosion-resistant materials,
It can be used for catalyst materials and civil engineering and construction fields.

[0002]

[Prior art and its problems] Alumina cement is CaO
_{Al 2 O 3, CaO · 2Al} 2 O 3, and hydraulic calcium aluminate mineral compositions shown as 12CaO · 7Al ₂ O ₃ or the like is blended with various raw materials such that the main melting and / or calcined to Hydraulic cement obtained by crushing the produced clinker alone or hydraulic cement crushed by mixing alumina and various additives with the clinker (Keiichi Akiyama, Chemistry of Cement and Concrete; p225-260, 1984; Author, Material Chemistry of Cement; p215-218,1991; refractory; Vol.29, p368-374,197
7, refractory; Vol.34, p634 ~ 640,1982, refractory; Vol.35, p19
0-199,1983, and Trans.J.Br.Ceram.Soc .; Vol. 81 (2), 1
982).

[0003] These alumina cements have been studied for a long time mainly in Europe, and generally include methods for producing alumina cement, characteristics of various mineral compositions, methods of adjusting hardening by various additives, and irregular refractories. (TDRobson, High Alumina Cemen)
ts and Concrete; p1-45,1962, refractory; Vol.34, p499-5
03,1982, and Chemistry of Cement Clinker (Part 1); S
ymposium held October 7-11, Vol.11968, Tokyo, p349〜3
65 etc.).

Further, for the purpose of high fire resistance and high strength development under high temperature, α-Al ₂ O ₃ , carboxylic acids, and the like are added to the mineral composition composed of CaO.Al ₂ O ₃ and 12CaO.7Al ₂ O ₃ . Alumina cement blended with inorganic carbonates and the like (Japanese Patent Publication No. 50-28090 and Japanese Patent Application Laid-Open No. 55-45507), and clinker of calcium aluminate, having a specific surface area of 1 to 30 m ² / g, average Hole diameter
Refractory calcium aluminate cement mixed and ground with alumina having an outer brain surface morphology of 0.05 to 0.5 μm (JP-A-5
No. 2-111920) has been proposed. However, these alumina cements do not have sufficient sinterability, abrasion resistance, and corrosion resistance when used at high temperatures, and are mixed with a filler such as fused silica or silicon carbide using the alumina cement as a binder to form a ceramic member. In applications such as the production of dies, there are problems such as clogging of the mold due to the large particle size and the large amount of coarse powder.

[0005] In the alumina cement compositions described in these patents and literatures, the pot life can be secured if fine alumina is blended after drying to improve strength when used at a high temperature of 600 to 1,800 ° C. There was a problem that it was not possible or the strength development after curing was reduced.

As a result of intensive studies to solve these problems, the present inventors have focused on the particle size composition and chemical components of alumina cement, and have found that coarse powder over 45 μm should be reduced and a specific chemical component should be provided. With the knowledge described above, the present invention has been completed.

[0007]

That is, the present invention provides a method for producing a particle having a particle size of 1.
under μm, 1-2 μm, 2-4 μm, 4-8 μm, 8-16
μm, 16-45 μm, and 45 μm with powder on 45 μm
The upper coarse powder is alumina cement of 1.0% by weight or less, and the particle size is 1 μm, 1 to 2 μm, 2 to 4 μm,
Powder on ８8 μm, 8-16 μm, 16-45 μm, and 45 μm
Alumina cement having a powder having a powder content of not more than 1.0% by weight on 45 μm, CaO of 15 to 30% by weight of a chemical component, and 70 to 85% by weight of Al ₂ O _3. It is an irregular-shaped refractory containing an aggregate.

Hereinafter, the present invention will be described in detail.

The alumina cement used in the present invention is:
The coarse powder on 45 μm is less than 1.0% by weight,
In coarse powder above 1.0 weight percent, CaO chemical components 15 to 30 wt%, Al ₂ O ₃ is alumina cement 70 to 85% by weight.

[0010] Alumina cement used in the present invention, a CaO material, such as limestone or lime, natural Al ₂ O ₃ raw material, such as bauxite or red bauxite, purification methods such as those natural Al ₂ O ₃ raw material buyers process High-purity alumina obtained by purification in, and Al ₂ O ₃ raw materials such as aluminum residual ash are blended so that the mineral composition in the heat-treated product becomes a predetermined ratio, an electric furnace, a reflection furnace, and a vertical furnace. Mold furnace, blast furnace, open hearth, cupola,
Rotary kilns, shaft kilns, shuttle kilns and other equipment are used to pulverize clinker obtained by melting and / or firing, or to mix and pulverize this clinker with α-Al ₂ O ₃ and various additives. Is what is done. The firing method, the Ceramic Association Journal; Vol.83 (5), as described in P239～243,1975, CaO raw material and Al ₂ O ₃ for starting material by the formation reaction of the calcium aluminate proceeds by a solid-phase diffusion reaction In addition, a multiphase mineral composition is easily formed in the clinker, and the mineral composition intended in the present invention tends to be hardly obtained. Therefore, in the present invention, it is preferable to produce clinker by a melting method in which the mineral composition ratio of calcium aluminate is easily produced within the object of the present invention as compared with clinker produced by a firing method. In the melting method, the formation reaction of calcium aluminate proceeds thermodynamically, so that the desired mineral composition of the present invention can be obtained relatively easily. When clinker is manufactured by a melting method, a CaO raw material and an Al ₂ O ₃ raw material are mixed and / or mixed and pulverized at a predetermined ratio, and heated in a melting furnace such as an electric furnace, a flat furnace, or a reflection furnace at a high temperature of 1,500 ° C. or more. , And more preferably until the unreacted raw material completely disappears.

[0011] It is preferable that the blended raw material is melted and then brought into contact with high-pressure air or water and cooled to obtain alumina cement clinker. In the pulverization and mixing of these clinkers, the clinkers may be mixed and then pulverized, or each pulverized mixture may be mixed. In particular, means for achieving the desired mineral composition ratio is limited. Not something. Clinker is usually used for pulverization of a lump, for example, after pulverization with a pulverizer such as a roller mill, a jet mill, a tube mill, a ball mill, and a vibration mill,
It is necessary to remove coarse powder with an air classifier such as a micron separator or cyclone. Generally, there is a limit in reducing coarse powders using only a pulverizer used for pulverizing alumina cement. Usually, 10 wt% or more of coarse powders having a size of 45 μm are present.

In the present invention, 45 μm in alumina cement
It is important to remove the coarse powder so that the upper coarse powder is 1.0% by weight or less, and more preferably 0.8% by weight or less. If it exceeds 1.0% by weight on 45 μm, sinterability, abrasion resistance and corrosion resistance during high temperature use may be reduced.

Further, the alumina cement of the present invention has a particle size of 45 μm.
not only the amount of coarse powder on m, but also the particle size distribution,
It is preferable not to include 63 μm above from the filling property when alumina cement is used. As the particle size distribution, 5 to 10% by weight under 1 μm, 3 to 5% by weight of 1 to 2 μm, 2 to 4 μm 10
~ 20% by weight, 4 ~ 8μm 20 ~ 30% by weight, 8 ~ 16μm20 ~
30% by weight, 16 to 45 μm 20 to 25% by weight, and 1.0 on 45 μm
% By weight or less is preferred. If the amount of fine powder of 1 μm or less is too large, the pot life when used for an amorphous refractory or the like may not be secured, and if the particle size of 2 to 16 μm is insufficient, the filling property may be deteriorated.

Further, in the present invention, alumina cement having a chemical composition of CaO of 15 to 30% by weight and Al ₂ O ₃ of 70 to 85% by weight is used as an amorphous refractory. preferably is excellent in sintering property at fluidity and high temperature during construction, CaO is 18-25 wt%, Al ₂ O ₃ is more preferable that was adjusted to 72 to 75 wt%. If the content of CaO is small, the strength development after curing may be insufficient, and if the content of CaO is too large, the corrosion resistance at high temperatures may be reduced.

In the present invention, the mineral composition is important in addition to the amount and chemical composition of the coarse powder in the alumina cement, and CaO.Al ₂ O
_{3, CaO · 2Al 2 O 3} , 12CaO · 7Al 2 O 3, and α-Al ₂ O ₃ one selected from or alumina cement containing two or more mineral composition may be used.

In the present invention, the mixing ratio of the mineral composition is Cu
It can be analyzed by X-ray diffraction analysis using -Kα ray. As a method of quantifying the mineral composition by the X-ray diffraction method, there are an intensity ratio measurement method of a diffraction line, an internal standard method, a Zevine method, an X-ray diffraction peak separation method, and the like. In the present invention, any method can be used for quantification. . The method of measuring the intensity ratio of diffraction lines as used herein refers to a value that relatively represents the diffraction intensity of each mineral composition, and the internal standard method refers to a method in which an internal standard substance and a sample are mixed at a fixed ratio. This method is based on the fact that a linear relationship is obtained between the component concentration and the diffraction line intensity ratio, and a calibration curve is prepared and analyzed using a standard sample having a known concentration. Also, Zevi
The ne method is a method of measuring an average mass absorption coefficient and a diffraction line intensity ratio of a sample and quantifying each crystal phase by solving an n-order simultaneous equation. Here, the average mass absorption coefficient is the fluorescence X
The components of the sample can be quantified and calculated by a line analysis method or a chemical analysis. In addition, it can be quantified by an X-ray diffraction peak separation method measured from the crystal or glass phase of the sample.
In the present invention, it is possible to quantify the mineral composition and the vitrification rate by any of the methods.
Or the method of measuring the intensity ratio of diffraction lines is preferred.

The vitrification rate of the clinker in the present invention can be adjusted by the cooling rate of the molten and / or calcined high-temperature clinker, and is not particularly limited.
In the case of the alumina cement of the present invention and the amorphous refractory using the same, a high vitrification rate is preferable because a long pot life can be obtained. The vitrification ratio is determined by analyzing the mineral composition by the powder X-ray diffraction method. The lower the diffraction line intensity, the higher the vitrification ratio. In the present invention, the vitrification rate is preferably 10% or more, and more preferably 30% or more, from the viewpoint of ensuring the pot life. The vitrification ratio can be measured by disappearance of the diffraction line by the powder X-ray diffraction method, and the vitrification ratio (%) = 100−
It can be calculated from (peak area / total diffraction line area) × 100. Generally, a method is employed in which clinker produced by melting or baking is brought into contact with water or air to cool the clinker. However, rapid cooling during cooling tends to increase the vitrification rate. Among calcium aluminates, 12CaO ・ 7Al ₂ O ₃ and
A material having a large C / A, such as 3CaO.Al ₂ O ₃ , has a rapid hardening property when the vitrification rate is increased, because the hydration reaction is promoted. In contrast, CA ₂ and 2CaO · 5Al ₂ O ₃ having a small C / A, such as shows a curing delayed to increase the vitrification ratio. For this reason, the vitrification rate of the alumina cement of the present invention containing CA ₂ as a main component is preferably higher from the viewpoint of ensuring the pot life.

The specific surface area (Brain value) of the brane of the alumina cement of the present invention can be measured by the method described in JIS R 2521, and is an important control point because it is involved in fluidity, curability, and strength development. there are, particle size of the milled clinker is preferably Blaine 4,000~12,000cm ² / g, more preferably 5,000~10,000cm ² / g, 6,000~8,0
00 cm ² / g is most preferred. If the Blaine value is out of this range, the fluidity and strength development may decrease.

The average particle size is a value of a particle size measured by a generally used particle size distribution measuring device such as a laser diffraction method, a laser scattering method, or a sedimentation balance method, and is 50% average particle size. Finely pulverized to 20 μm or less is preferable since it has excellent fluidity and can secure a usable life at a high temperature, and is more preferably 1 to 15 μm. Average particle size is 20μ
If it exceeds m, the fluidity may decrease and curing may be delayed.

Further, for the purpose of improving the fire resistance and the sinterability at high temperatures, it is preferable to add α-Al ₂ O ₃ to the alumina cement of the present invention, if necessary. It is preferable to carry out mixing and grinding with clinker.

In particular, in the present invention, the BET specific surface area is 0.4
It is preferred to use ~ 0.8 m ² / g of α-Al ₂ O ₃ , BE
T specific surface area is 0.4-0.8m ² / g, average particle size is 40-90μm
It is more preferable to use α-Al ₂ O ₃ containing 0.1% by weight or less of soluble Na ₂ O and 0.05% by weight or less of soluble SO ₃ as a chemical component.

[0022] The α-Al ₂ O _3, a purified alumina obtained by calcining a highly purified treated aluminum hydroxide by the buyer processes like in the rotary kiln, Al ₂ O
High-purity alumina containing 90% by weight or more of ₃ and is generally called high-purity alumina, Bayer alumina, easily sintered alumina, or lightly burned alumina.

In the present invention, a significant BET specific surface area of α-Al ₂ O ₃ is preferably ^{0.4~0.8m 2 / g, 0.5~0.7m 2 /} g
Is more preferred. If the BET specific surface area is less than 0.4 m ² / g, the high-temperature strength developability when used for an amorphous refractory may decrease.If the BET specific surface area exceeds 0.8 m ² / g, the pot life and fluidity of the alumina cement may decrease. In some cases, it cannot be secured. α-Al ₂
The BET specific surface area of O ₃ can be adjusted by controlling the sintering temperature and the residence time in the sintering apparatus when sintering aluminum hydroxide as a raw material in a sintering apparatus such as a rotary kiln, a tunnel kiln, and a shuttle kiln. Therefore, when the firing temperature is increased, the BET specific surface area tends to decrease, and when the firing temperature is decreased, the BET specific surface area tends to increase. B
Α-Al ₂ O ₃ with an ET specific surface area of 0.4 to 0.8 m ² / g is 1,200 to 1,450
It can be manufactured by firing at a temperature of ° C.

Further, the particle size of α-Al ₂ O ₃ is also important, and the particle size of α-Al ₂ O ₃ is preferably 40 to 90 μm. If the particle size is small, it becomes too small when mixed and pulverized with clinker, so that the pot life and fluidity as alumina cement may not be secured, and if the particle size is large, it takes time to pulverize, and it is mixed and pulverized with clinker When it is not finely crushed,
When alumina cement is used, the particle diameter increases, and when used for irregular-shaped refractories, strength development and fluidity at high temperatures may be reduced. The particle size of α-Al ₂ O ₃ can be controlled by adjusting the precipitation time of aluminum hydroxide when producing aluminum hydroxide by the Bayer method. If the precipitation time is long, aluminum hydroxide having a large particle diameter can be obtained, and α-Al ₂ O ₃ obtained by calcining the aluminum hydroxide also has a large particle diameter.

The method of producing alumina by the Bayer method is described in 1881 by Karl J, an Austrian chemist.
An industrial production method of alumina invented by osef Bayer, in which bauxite impurities TiO ₂ and Fe ₂ O
₃ is insoluble in aqueous sodium hydroxide, SiO ₂ soluble in aqueous sodium hydroxide,
Reacts with Na ₂ O and Al ₂ O ₃ to form a sodalite compound (3Na ₂ O ₃・ 3
Al ₂ O ₃・ SiO ₂ ) is generated and insolubilized, and after obtaining an aqueous solution of sodium aluminate containing no impurities,
This solution is a method for producing a target α-Al ₂ O ₃ by precipitating aluminum hydroxide crystals by cooling and supersaturating the solution, and firing the crystals in a firing device such as a rotary kiln. .

In the present invention, the size of α particles of α-Al ₂ O ₃ is important. The size of the alpha particles, an electron microscope α-Al ₂ O ₃
It can be measured by observing the particle surface,
Preferably it is 5 μm. α particle size is 2μm
If the particle size is smaller than the above, the pot life and fluidity may not be secured. If the size of the α particles is larger than 5 μm, the particle size after being mixed and pulverized with clinker also becomes large, and the high-temperature strength is exhibited when used as an amorphous refractory. Performance may be reduced.

Furthermore, in the present invention, the shape of the α particles is also important, and it is preferable that the shape is closer to a sphere because the fluidity of alumina cement is improved, but as the sphericity increases, the bending strength also increases. Tends to decrease. The shape of the α particle indicates a geometric shape and is indicated by sphericity and shape factor. The smaller the sphericity and shape factor, the closer to a sphere, the closer the shape factor is 6. Indicates a ball. The sphericity is determined by, for example, crushing α particles constituting α-Al ₂ O ₃ by a ball mill, and sphericity = (4.84 × k ^2/3 ) / f, where k is a volume shape factor, and f is Can be calculated from the area shape factor), and the shape factor can be calculated as shape factor = (α-Al ₂ O ₃ crushed α
(BET specific surface area of particles) × (average particle diameter of α particles obtained by crushing α-Al ₂ O ₃ ) × (true specific gravity of α-Al ₂ O ₃ ) (Chemical Engineering Handbook; Revised 5th edition) , p220-224,1988). α-Al ₂
Disintegrated to α particles O ₃ is possible by a batch-type ball mill or a batch type vibration mill, for example, the internal volume 10
It is possible to disintegrate the mixture by putting 1 kg of alumina balls having a ball diameter of 10 mm and 500 g of α-Al ₂ O ₃ into a liter mill and grinding them for about one hour. In the present invention, the shape factor is preferably 19 or less, more preferably 16 or less. This shape factor is used to control the crystal shape of α particles during firing of α-Al ₂ O ₃ , and aluminum fluoride (AlF ₃ ) is retained in the kiln as a catalyst for the conversion reaction of α conversion, but its concentration is reduced. By adjusting the shape, the shape can be controlled, and if the amount of retained aluminum fluoride is large, the shape of the α particles is flattened. To reduce the shape factor, the amount of aluminum fluoride must be reduced. preferable.

The purity of α-Al ₂ O ₃ has never been higher if it is higher. However, if the alumina is produced by a usual Bayer process, the purity of Al ₂ O _{3 is} 98% by weight or more. It is enough because it is possible to secure. In the present invention, in addition to the Al ₂ O ₃ purity, the amount of impurities such as Na ₂ O and SO ₃ is also important. Α-Al ₂ O ₃ used in the present invention, in the process of producing the α-Al ₂ O ₃ in the Bayer process, as soluble Na ₂ O is reduced, thoroughly washing the obtained aluminum hydroxide, it It is preferable that the material is calcined using as a raw material, and that the sodium content is removed. Soluble Na ₂ O, preferably 0.1 wt% or less, more preferably 0.05 wt% or less. When the amount of soluble Na ₂ O is increased, when alumina cement is used, Na ions may act as a hardening accelerator, making it impossible to ensure the pot life and fluidity. Also, total Na
₂ O is preferably smaller, preferably 0.5% by weight or less,
A low sodium type of 0.35% by weight or less is more preferable. When the total amount of Na ₂ O is large, when the alumina cement is used, the fluidity may be reduced, the fire resistance may be reduced, and the alumina cement may be shrunk at a high temperature. Most of the soluble SO ₃ is contained in α-Al ₂ O ₃ from fuels such as heavy oil and coal when baking aluminum hydroxide, and its amount should be 0.05% by weight or less. Is preferred in terms of the quality characteristics of the alumina cement. If the amount of the soluble SO ₃ is large, the curing of alumina cement may be delayed.

The amount of α-Al ₂ O ₃ used in the present invention is preferably 10 to 55 parts by weight, more preferably 20 to 30 parts by weight, per 100 parts by weight of alumina cement. If the amount of α-Al ₂ O ₃ is too large, the strength development and fluidity after curing may be insufficient, and if it is too small, the sinterability is insufficient and the effect of improving the strength development at high temperature use is sufficient. May not be.

The alumina cement of the present invention includes, in addition to the desired CaO.2Al ₂ O ₃ , CaO.TiO ₂ and 4CaO.A
Although those containing impurities such as l ₂ O ₃ and Fe ₂ O ₃ can be used, it is preferable that the amount of impurities in the alumina cement is small, and the total amount thereof is preferably 5% by weight or less, More preferably, TiO ₂ is 0.6% by weight or less, Fe ₂ O ₃ is 0.5% by weight or less, and MgO is 0.5% by weight or less. TiO ₂ , Fe ₂ O ₃ ,
And when impurities such as MgO increase, not only fire resistance,
Not only properties such as strength development, volume stability as a cured product under high temperature, and spalling resistance are deteriorated, but also corrosion resistance to slag and the like may be reduced.

Further, in the present invention, for the purpose of improving the fluidity of the alumina cement and the amorphous refractory using the same, the cement is usually blended with the amorphous refractory.
9, p3 to 7,1981, refractories; 3-393, p31 to 34,1981, and refractories; 40-5, p270 to 278, 1988, etc., such as curing retarders and curing accelerators Additives, fluidizers, etc. can be used in combination.

Examples of the curing retarder include carboxylic acids, alkali metal carbonates, boric acids, polyacrylic acids, polymethacrylic acids, and phosphoric acids, of which the use of carboxylic acids or carboxylic acids of alkali salts thereof is preferred. .

Here, the carboxylic acids are oxycarboxylic acids, specifically, citric acid, gluconic acid, tartaric acid, succinic acid, lactic acid, malic acid, and salicylic acid, or their sodium and potassium salts, And alkali salts such as calcium salts. Of these,
It is preferable to use citric acid or an alkali salt thereof, especially sodium citrate or potassium citrate. The purity of the carboxylic acids is not particularly limited, but currently, it is possible to use industrially purified carboxylic acids,
The purity of the target carboxylic acid is preferably about 80% by weight or more. In particular, the use of citric acid or a salt thereof containing 0.05% by weight or less of sulfate as an impurity, or citric acid or a salt thereof having a pH of 7 to 10 in an aqueous solution having a concentration of 1% by weight at 20 ° C. is difficult to use. It is preferable because it is excellent.

As the alkali metal carbonate, any of inorganic carbonates can be used. However, it is preferable to use an alkali metal carbonate such as sodium carbonate, potassium carbonate, sodium hydrogen carbonate and potassium hydrogen carbonate. Either salt or anhydrous salt can be used. Of these,
The use of sodium carbonate is preferred, JIS K 1201 or JIS K 8
It is possible to use the sodium carbonate specified in 625. The particle size of the alkali metal carbonate is preferably as small as possible so as to be easily dissolved in water when mixed with the alumina cement, and is preferably 100 mesh or less, particularly preferably 200 mesh or less. The purity of the alkali metal carbonate is not particularly limited, but it is possible to use an alkali metal carbonate which is currently industrially purified, and the purity of the target carbonate is about 80% by weight or more. The use of

The boric acids refer to boric acid or an alkali salt thereof. Boric acid is also called boric acid, orthoboric acid, or orthoboric acid, is denoted by H ₃ BO ₄ , and contains pyroboric acid, tetraboric acid, and metaboric acid. The method for producing boric acid is not particularly limited, but usually, the raw ore of boric acid is heated and decomposed by adding sulfuric acid to release and separate boric acid, followed by purification. Examples of the alkali salt of boric acid include a sodium salt, a potassium salt, and a calcium salt. Among them, the use of a sodium salt or a potassium salt is preferable, and any of a hydrated compound and an anhydrous compound thereof can be used. The particle size of the boric acids is preferably as small as possible so as to be easily dissolved in water when mixed with alumina cement. Further, the purity of boric acid is not particularly limited, but boric acid which is industrially purified can be used at present, and the boric acid having a BO ₄ content of 80% by weight or more is used. preferable.

Examples of the polyacrylic acids include polyacrylic acid and salts thereof, such as sodium polyacrylate, potassium polyacrylate, and ammonium polyacrylate. The use of sodium polyacrylate is most preferred because of its easiness and ease of handling. As polymethacrylic acids,
In polymethacrylic acid or salts thereof, sodium polymethacrylate, polypotassium methacrylate, and polyammonium methacrylate, etc., among them, performance, price, availability, and ease of handling, etc. Most preferred is the use of polysodium methacrylate. Examples of the phosphoric acids include hexametaphosphoric acid, tripolyphosphoric acid, and pyrophosphoric acid or an alkali salt thereof.

Examples of the curing accelerator include hydroxides such as sodium hydroxide, potassium hydroxide, and calcium hydroxide, and lithium salts such as lithium carbonate. Preferred from the strong side.

The amount of these additives is preferably 0.5 to 2.5 parts by weight, preferably 1.0 to 2.5 parts by weight, based on 100 parts by weight of alumina cement.
~ 2.0 parts by weight is more preferred. If the amount is less than 0.5 part by weight, workability tends to decrease, and if it exceeds 2.5 parts by weight, curing tends to be delayed and strength tends to decrease.

The fluidizing agent is an admixture containing a surfactant excellent in cement dispersibility as a main component, and is generally a salt of a naphthalene sulfonic acid formalin condensate (a naphthalene type), a melamine resin sulfonic acid formalin condensate. (Melamine-based) and olefin / maleic acid copolymer salts
(Carboxylic acid type) and the like can be used.Specifically, sodium salts of highly condensed β-naphthalenesulfonic acid, sodium salts of creosote oil sulfonic acid condensate, sodium salts of β-naphthalenesulfonic acid low condensate And polyoxyethylene nonylphenyl ether. The use amount of the fluidizing agent is not particularly limited, but is preferably 0.5 to 5 parts by weight based on 100 parts by weight of the amorphous refractory made of alumina cement and refractory aggregate.

The method of blending the additives and the fluidizing agent is not particularly limited, and the additives and the like are blended so as to have a predetermined ratio, and the pulverized alumina cement is mixed with a V-type blender, a corn blender, and a Nauta. A mixer, a pan-type mixer, and a homogenizer using a mixer such as an omni mixer, or after mixing alumina cement and additives in a predetermined ratio, a vibration mill, a tube mill, a ball mill, a roller mill, etc. It is possible to mix and pulverize with a pulverizer. Also, in the present invention, additives and the like 100 to 4
Heat at a temperature of 00 ° C and mix with alumina cement,
Alternatively, a method of heating a mixture of an additive or the like and alumina cement together is possible. As a heating method, a method of heating simultaneously with pulverization, a method of heating with hot air during transportation, a method of heating a transport machine, a method of heating during storage, and the like are possible. These additives are ICP, I
CPA, GC-MS, NMR, HPLC, and FT-I
The type and quantitative ratio can be specified by instrumental analysis such as R, chelate analysis, activation analysis, or the like.

The water used in the present invention is not limited in particular, tap water, natural water, and the water used for the concrete river water or the like generally available, Na ^{+,
K +, Mg 2 +, Ca} 2+, and Cl ^- use of less water soluble components are preferred. The amount of water used is appropriately determined depending on the intended amorphous refractory, and is not particularly limited. However, when the amount of water used is large, there is a tendency that breathing or strength development is reduced. Therefore, in the case of the irregular-shaped refractory to be cast, it is usually preferable to use 2 to 20 parts by weight based on 100 parts by weight of the irregular-shaped refractory. Generally, JIS R
It is preferable to add water so that the flow value measured by the method described in 2553 is 130 to 240 mm.

The refractory aggregate used in the present invention is a refractory aggregate.
When used in a low cement castable type consisting of 92 to 99% by weight and 1 to 8% by weight of alumina cement, the effect is more pronounced, and refractory aggregates usually used for amorphous refractories can be used. . Specific examples include magnesia, magnesia spinel, alumina, carbon, and ultrafine powder, and the like, as well as fused silica, calcined mullite, chromium oxide, bauxite, andalusite, sillimanite, chamotte, silica stone, raw Stone, clay, zircon, zirconia, dolomite, perlite,
Vermiculite, brick waste, pottery waste, silicon nitride, boron nitride, silicon carbide, iron silicon nitride, and the like can be used. In particular, the amorphous refractories of the present invention have corrosion resistance and durability.
(Durability) and fire resistance, it is selected from magnesia aggregate, magnesia spinel aggregate, alumina aggregate, carbon aggregate, ultra fine powder, and aggregate such as chamotte and silicon carbide. Preferably, one or more refractory aggregates are blended. In addition, when used in the molten steel process of the steelmaking process, from the viewpoint of slag permeation suppression, the combined use of magnesia aggregate and alumina aggregate or the combined use of magnesia spinel aggregate and alumina aggregate is preferable. When used in combination, alumina aggregates such as fused alumina and sintered alumina, carbon aggregates, ultrafine powder, and additives are preferably used in combination.

Here, the magnesia-based aggregate refers to a calcined material obtained by calcining magnesium hydroxide, magnesium carbonate, magnesite that is natural magnesia, natural magnesium carbonate, etc. extracted from seawater by the seawater method using a rotary kiln or the like. The sintered magnesia clinker, the fused magnesia clinker obtained by melting the sintered magnesia clinker in an electric furnace or the like, and further, a mixture of the sintered magnesia clinker and the fused magnesia clinker is crushed to a predetermined size and sieved. It is divided, and the purity of MgO is 80
When it is used as an amorphous refractory, it is preferred that it has excellent corrosion resistance, and it is preferable that the content of impurities such as SiO ₂ and TiO ₂ is small, and the purity of MgO is 95% by weight or more.
aO is 2% by weight or less, SiO ₂ is 0.5% by weight or less, and B ₂ O ₃ is
0.5% by weight or less of magnesia is preferable from the viewpoint of excellent corrosion resistance. Specifically, molten magnesia, sintered magnesia, natural magnesia, light-burned magnesia, and the like can be used.In addition, magnesia coated with spinel, magnesia containing magnesium titanate in grain boundaries, magnesia particles on the surface of magnesia particles Magnesia that produced calcium aluminate, high purity, high bulk density, and special magnesia of coarse crystal grains used for basic bricks, and crushed magnesia zirconia with improved heat spalling resistance Special magnesia can also be used. The MgO / Al ₂ O ₃ molar ratio in the magnesia clinker is preferably from 0.1 / 1 to 1/1, and more preferably from 0.2 / 1 to 0.4 / 1 from the viewpoint of excellent durability when blended with an amorphous refractory.

Magnesia spinel aggregate is a mixture of a MgO raw material such as magnesium hydroxide or calcined magnesia and an Al ₂ O ₃ raw material such as aluminum hydroxide or calcined alumina in a predetermined ratio. Magnesia spinel clinker reacted and fired at a temperature of about 1,800 to 1,900 ° C. using a firing device such as a rotary kiln, and a magnesia spinel clinker melted by a melting device such as an electric furnace. A magnesia spinel clinker obtained by mixing a calcined material and a molten material is pulverized to a predetermined size and sieved. Specific examples include a molten magnesia spinel and a sintered magnesia spinel.

The alumina-based aggregate is obtained by melting and / or firing an Al ₂ O ₃ raw material such as aluminum hydroxide or calcined alumina in a melting device such as an electric furnace or a firing device such as a rotary kiln. And sieved. The mineral composition is α-Al ₂ O ₃ or β-Al ₂ O ₃
And the like, and are called electrofused alumina, fused alumina, sintered alumina, calcined alumina, easily sintered alumina, and the like. Usually Al ₂ O ₃
Most preferably, α-Al ₂ O ₃ containing 90% by weight or more is used. Specific examples include fused alumina, sintered alumina, lightly fired alumina, easily sintered alumina, and the like. Also obtained by melting alumina and zirconia clinker,
It is also possible to use alumina / zirconia clinker or the like having improved heat resistance spalling property.

As the carbonaceous aggregate, oil pitch,
Tar and scale graphite.

The refractory aggregate is prepared by mixing various particle sizes according to required physical properties. The particle size of the refractory aggregate is usually 5 to 3 mm,
4-1 mm, 3-1 mm, 1 mm below, 200 mesh below, and 325
It is divided under the mesh (below 45 μm).

In the present invention, as the refractory aggregate, it is possible to use ultrafine powder having a fine particle diameter. Here, the ultrafine powder is a refractory fine powder in which particles having a particle diameter of 10 μm or less are 80% by weight or more and have an average particle diameter of 1 μm.
In the following, those having a specific surface area of 10 m ² / g or more by the BET method are preferable because they have excellent fluidity and high strength when incorporated into an amorphous refractory. Specifically, inorganic fine powders such as silica fume, colloidal silica, light-burned alumina, easily sintered alumina, amorphous silica, zircon, silicon carbide, silicon nitride, chromium oxide, and titanium oxide can be used. Of these, use of silica fume, colloidal silica, and easily sintered alumina fine powder is preferred. In particular, silica fume used in low-cement castables is important because the pH of the slurry when forming a slurry affects the dispersibility, and a weakly acidic to acidic one is particularly preferred in terms of ensuring a usable life.

The amount of the refractory aggregate of the present invention should be appropriately determined depending on the construction site, and is not particularly limited, but is preferably 50 to 99 parts by weight based on 100 parts by weight of the amorphous refractory. From the viewpoint of corrosion resistance, 85 to 90 parts by weight is more preferable. In the low cement castable using ultra fine powder as the refractory aggregate, 1 to 6 parts by weight of alumina cement, refractory aggregate
It is preferable to mix 94 to 98 parts by weight and 5 parts by weight or less of silica fume from the viewpoint that remarkable fluidity and working life can be secured.

Although the method for producing the amorphous refractory of the present invention is not particularly limited, each raw material is blended so as to have a predetermined ratio in accordance with the usual method for producing an irregular refractory.
Type blender, cone blender, Nauta mixer,
It is also possible to perform uniform mixing using a mixer such as a pan-type mixer and an omni mixer, or to directly weigh the mixture into a kneading machine when performing kneading at a predetermined ratio.

Further, the amorphous refractory of the present invention includes metal powders such as metal aluminum and silicon alloy, organic fibers such as vinyl fiber and polypropylene, for the purpose of preventing explosion which is likely to occur when the cured body is dried. It is also possible to add a nitrogen-containing gas product and an anti-explosion agent such as dextrin if necessary. The amount of the explosion-preventing agent to be used must be determined appropriately according to the intended explosion resistance and cannot be unambiguously determined.
It is possible to mix 0.05 to 5 parts by weight with respect to 100 parts by weight.

[0052]

The present invention will be further described below with reference to examples.

Example 1 A mixture of a CaO raw material and an Al ₂ O ₃ raw material was melted in an electric furnace, and then the melt was quenched by high-pressure cooling air to synthesize clinkers having different chemical components. Furthermore, using a Hosokawa Micron micron separator, air classification was performed and the amount of coarse powder on 45 μm was adjusted. Igloss was 0.2% by weight, and TiO ₂ , Fe ₂ O ₃ , and MgO were each less than 0.1% by weight. ,
Alumina cement was produced in the amount of coarse powder on 45 μm shown in Table 1. 15 parts by weight of the produced alumina cement and 85 parts by weight of refractory aggregate a were blended into an amorphous refractory, and 9.5 parts by weight of water was added to 100 parts by weight of the amorphous refractory, followed by mixing with a mixer for 5 minutes. After kneading, the flow value as a fluidity, the curing time, the curing strength and the drying strength as the room temperature strength, and the firing strength as the high temperature strength were measured. All measurements were performed in a constant temperature room at 20 ° C. The results are shown in Table 1 together with the amount of the coarse powder and the chemical components.

<Materials> CaO raw material: commercial quicklime Al ₂ O ₃ raw material: high-purity alumina produced by the Bayer method,
Commercial product, Al ₂ O ₃ purity 99% by weight, average particle size 70 μm Refractory aggregate a: sintered alumina, commercial product, particle size 5 to 3 mm 40% by weight, particle size 3 to 1 mm 45% by weight, 10% by weight under 1 mm, and 45
5% by weight under μm

<Measurement method> Chemical analysis: Measured according to JIS R 2522 Coarse powder: Using a 45 μm sieve or 63 μm sieve, sieving by a water flow, drying the upper part of the sieve, and measuring the amount ： Evaluation of fluidity, after leaving the kneaded material in a 20 ° C constant temperature room for a predetermined time, measuring by tapping 15 times. Curing time ： From the water injection when the kneaded material was left in a 20 ° C constant temperature room using a temperature recorder Time until the exothermic temperature reaches the maximum Curing strength: room temperature strength Compressed strength after putting the kneaded material in a 4 × 4 × 16 cm mold for 24 hours in a constant temperature room at 20 ° C. Dry strength: normal temperature strength, 24 hours After curing, 110 ° C
Compressive strength after drying for 24 hours at a temperature Firing strength: High temperature strength, dried at 110 ° C, put in a siliconite electric furnace, baked at 1,000 ° C for 3 hours, and left to cool to room temperature, compressive strength

[0056]

[Table 1]

As shown in Table 1, the amorphous refractory blended with the alumina cement of the present invention had excellent fluidity and high strength after firing at high temperatures.

Example 2 0.2% by weight of Igloss, 33.5% by weight of CaO, 65.8% by weight of Al ₂ O ₃ and 0.7% by weight of SiO ₂ , TiO ₂ , Fe ₂ O ₃ and MgO
Was less than 0.1% by weight in each case, and the same procedure as in Example 1 was carried out except that the amount of alumina cement shown in Table 2 was used. The results are also shown in Table 2.

[0059]

[Table 2]

Example 3 0.2% by weight of Igloss, 33.5% by weight of CaO, 65.8% by weight of Al ₂ O ₃ and 0.7% by weight of SiO ₂ , TiO ₂ , Fe ₂ O ₃ and MgO
Using clinker of less than 0.1% by weight respectively, blending α-Al ₂ O ₃ so that CaO, Al ₂ O ₃ , and SiO _{2 of} the alumina cement become the amount shown in Table 3, and mixed and pulverized with a ball mill, Alumina cement was manufactured by reducing the amount of coarse powder above 45 μm with a Yaskawa Electric's classifier “Micro Cut”. 3 parts by weight of the produced alumina cement, 79 parts by weight of refractory aggregate a, 15 parts by weight of refractory aggregate b, 3 parts by weight of refractory aggregate c, and additive A
0.03 parts by weight of the additive B and 0.05 part by weight of the additive B were blended to obtain an amorphous refractory. For 100 parts by weight of this refractory, 7.5 parts of water
The same procedure as in Example 1 was carried out except that the parts by weight were added and kneaded with a mixer for 5 minutes. The results are also shown in Table 3.

<Materials Used> Refractory aggregate b: fine alumina powder, commercially available, particle size of 45 μm or less Refractory aggregate c: ultrafine powder, silica fume, commercially available additive A: boric acid, reagent manufactured by Kanto Chemical Co., Ltd. additive B: Sodium tripolyphosphate, reagent manufactured by Kanto Chemical Co., Ltd. Commercial alumina cement α: Commercial product, Igloss 0.2% by weight, T
iO ₂ and MgO are less than 0.1% by weight, Fe ₂ O ₃ 0.2% by weight Commercial Amina cement β: Commercial product, Igloss 1.0% by weight, TiO
₂ and MgO less than 0.1% by weight, Fe ₂ O ₃ 0.1% by weight

<Measurement method> Pot life: Time required for transferring the kneaded material into a nylon bag in a constant temperature room at 20 ° C. and curing with a touch finger

[0063]

[Table 3]

As shown in Table 3, the amorphous refractories blended with the alumina cement of the present invention had excellent fluidity and high strength after firing at high temperatures.

Example 4 0.3% by weight of Igloss, 22.5% by weight of CaO, 77.2% by weight of Al ₂ O ₃ and 0.3% by weight of SiO ₂ , TiO ₂ , Fe ₂ O ₃ and MgO
Was less than 0.1% by weight in each case, less than 0.1% by weight on a particle size of 63 μm, and the amount of coarse powder shown in Table 4 was used in the same manner as in Example 3 except that alumina cement was used. The results are also shown in Table 4.

[0066]

[Table 4]

Example 5 A commercial alumina cement α was classified and reduced in size by 45 μm, and the same operation as in Example 3 was performed except that a commercially available alumina cement α was used for comparison. Table 5 shows the results. 1 and Table 6 show the measurement results of the particle size distribution of each alumina cement.

<Measurement Method> Particle size distribution: Measured with a Cirrus Model 715 type laser particle size distribution analyzer, using ethanol as the first grade reagent as a solvent.

[0069]

[Table 5]

As shown in Table 5, the amorphous refractory containing the alumina cement of the present invention was excellent in fluidity and high in strength after firing at high temperature.

[0071]

[Table 6]

[0072]

The alumina cement of the present invention and the amorphous refractory using the same have high fluidity and high-temperature sinterability not found in conventional products, and are mainly used in the field of refractories in which alumina cement is used. It can be used for ceramic materials, lining of chemical plants, corrosion-resistant materials, catalyst materials and civil engineering and construction fields.

[Brief description of the drawings]

FIG. 1 shows the particle size distributions of the alumina cement of the present invention and a commercially available alumina cement (comparative example).

──────────────────────────────────────────────────の Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C04B 7/32 C04B 28/06 JICST file (JOIS)

Claims (3)

(57) [Claims] (1) a particle size of 1 μm, 1-2 μm, 2-4 μm
m, 4-8 μm, 8-16 μm, 16-45 μm, and 45 μm
Alumina cement having the above powder, wherein the coarse powder on 45 μm is 1.0% by weight or less. 2. Particle size: 1 μm, 1-2 μm, 2-4 μm
m, 4-8 μm, 8-16 μm, 16-45 μm, and 45 μm
An alumina cement having the above powder, wherein the coarse powder on 45 μm is 1.0% by weight or less, the chemical component CaO is 15 to 30% by weight, and the Al ₂ O ₃ is 70 to 85% by weight. 3. An amorphous refractory comprising the alumina cement according to claim 1 and a refractory aggregate.