JPH09278500A - Alumina cement, alumina cement composition and prepared unshaped refractory using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an alumina cement having excellent CO gas resistance never shown in the conventional articles and excellent in volume stability and resistance against the change of color tone of a hardened body in the case of exposing the hardened boy for a long period by controlling the contents of Fe and FeO in the alumina cement to be lower than a specific value. SOLUTION: The alumina cement contains <=0.1wt.% each of Fe and FeO as chemical components. An alumina cement composition improved in fire resistance and sintering property at a high temp. is formed by blending α-Al2 O3 with the alumina cement. A prepared unshaped refractory is formed by blending a refractory aggregate with the alumina cement or the alumina cement composition. As a method to reduce the content of Fe and FeO in the alumina cement, for example, a method of using a CaO raw material or an Al2 O3 raw material small in iron content and a method of melting in a carbon lining furnace at the time of producing a clinker by a melting method in an electric furnace or the like are mentioned.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an alumina cement,
Alumina cement composition, and amorphous refractories using the same, especially, CO gas resistance, volume stability, and characteristics that the cured product has little color change when exposed to the cured product for a long time Is to have. Alumina cement of the present invention, alumina cement composition, and amorphous refractory using the same, mainly in the refractory field where alumina cement has been used conventionally, lining of chemical plants,
It can be used for corrosion resistant materials, catalyst materials, and civil engineering and construction fields.

[0002]

[Prior art and its problems] Alumina cement is CaO
・ Al_TwoO_Three, CaO2Al_TwoO_Three, And 12CaO ・ 7Al_TwoO_ThreeAnd so on
Mainly composed of hydraulic calcium aluminate of mineral composition
By blending various raw materials, melting and / or firing
Hydraulic cement obtained by crushing the produced clinker alone, or
Grinds the clinker with alumina and various additives.
It is a hydraulic cement that has 2CaO
Al_TwoO_Three・ SiO_Two, 4CaO / Al_TwoO_Three・ Fe_TwoO _Three, And CaO ・ TiO_Two
It contains minerals such as
Various introductions (Keiichi Akiyama, Cement Concrete)
Chemistry of pt; p225-260, 1984, Yasuo Arai, Cement
Material Chemistry; p215-218, 1991, Refractories; Vol.29, p368-37
4,1977, refractories; Vol.34, p634 ~ 640,1982, refractories; Vo
l.35, p190-199,1983, and Trans.J.Br.Ceram.Soc .; V
81 (2), 1982).

Further, these alumina cements have been studied for a long time mainly in Europe,
A general method for producing alumina cement, characteristics of various mineral compositions, hardening adjustment method with various additives, and application method for amorphous refractories were proposed (TDRobson, High Alum
ina Cements and Concrete; p1 ~ 45,1962, refractory; Vo
l.34, p499-503,1982, and Chemistry of Cement Clin
ker (Part1); Symposiumheld October 7-11, Vol.11968,
Tokyo, p349-365 etc.).

The content of Fe ₂ O ₃ in these alumina cements is usually 0.3% by weight or more, and Fe ₂ O _{3 is} 0.2% by weight or less by deferring the alumina cement.
It has been proposed to solve the problems of expansion / cracking due to alkali vapor infiltration, cracking due to CO gas infiltration, and peeling due to thermal spall or impact / abrasion.
-267744).

Further, when alumina cement is used as a binder for a spray repair material on the wall surface of the shaft portion of the blast furnace for the purpose of extending the life of the blast furnace, when the CO gas, alumina cement, or fireproof bone filled in the blast furnace is used. It was found that the spalling resistance and volume stability were poor due to the iron content in the material, and it was proposed to perform low iron differentiation treatment of the raw material to improve C0 gas resistance (refractory material , Vol.45 (1
1), p673, 1993). However, Fe ₂ O ₃
Even if you use alumina cement with less than 0.2% by weight,
Due to the difference in the oxidation form of the iron component contained in the alumina cement, CO resistance is not sufficient, when used as a lining material for a blast furnace, a volume change occurs in the hardened material such as the lining material, or cracks occur, There was a problem that when the cured product was exposed and cured for a long time, the color tone changed and the appearance became poor when concrete was spliced. In particular, in conventional alumina cement, when the hardened material is exposed for a long time due to the iron content in the raw material or the iron content mixed during pulverization, the hardened material turns red due to the morphological change due to the oxidation of the iron content. There is a problem of color tone change, and when used for civil engineering and construction applications, there is a problem that the appearance becomes poor and the commercial value decreases.

As a result of earnest studies to solve these problems, the present inventor found that Fe and FeO contained in alumina cement
, Fe ₃ O ₄ , and Fe ₂ O ₃ have different reactivity with CO gas and oxygen gas due to the difference in their forms, and among the various iron forms, Fe and FeO have the highest C0 gas resistance. The present invention has been completed with the knowledge that the above problems can be solved by affecting the prevention of color change during long-term exposure, and in particular, if the contents of Fe and FeO in alumina cement are each 0.1 wt% or less. Came to.

[0007]

Means for Solving the Problems That is, the present invention is an alumina cement containing 0.1% by weight or less of Fe and FeO as chemical components, and containing the alumina cement and α-Al ₂ O _3. Which is a non-standard refractory material obtained by blending the alumina cement or the alumina cement composition with a refractory aggregate.

Hereinafter, the present invention will be described in detail.

The alumina cement according to the present invention is CaO.
Al ₂ O ₃ (CA), CaO ・ 2Al ₂ O ₃ (CA ₂ ), 12CaO ・ 7Al ₂ O ₃
(C ₁₂ A ₇ ), CaO ・ 6Al ₂ O ₃ (CA ₆ ), 3CaO ・ 5Al ₂ O ₃ (C ₃
A ₅ ), 5CaO ・ 3Al ₂ O ₃ (C ₅ A ₃ ), and 3CaO ・ Al ₂ O ₃ (C ₃ A
), Etc., as well as calcium aluminate having a mineral composition, 2CaO ・ Al ₂ O ₃・ SiO ₂ caused by raw material impurities, etc.
(C ₂ AS), 4CaO ・ Al ₂ O ₃・ Fe ₂ O ₃ (C ₄ AF), CaO ・ TiO ₂
(CT), α-Al ₂ O _{3 and the} like.

Further, the alumina cement composition according to the present invention preferably contains, as a mineral composition, two or more kinds of CA, CA ₂ and C ₁₂ A ₇ and α-Al ₂ O ₃ . CA,
It is more preferable to contain CA ₂ , α-Al ₂ O ₃ , and CA, CA ₂ , C ₁₂ A ₇ , and α-Al ₂ O ₃ because of excellent CO resistance and little change in color tone.

Alumina cement is limestone or quicklime.
CaO raw materials and heavens such as bauxite and red bauxite
Natural Al_TwoO_ThreeRaw material, these natural Al_TwoO_ThreeBuy raw materials
High-purity alumina obtained by refining by a refining method such as process
In addition, aluminum such as aluminum residual ash_TwoO _ThreeCombined with raw materials, electricity
Furnaces, reverberatory furnaces, vertical furnaces, blast furnaces, open hearth furnaces, and cupolas
, Rotary kiln, shaft kiln, and shuttle
Cleanse obtained by melting and / or firing in equipment such as kiln
It is possible to crush the car and manufacture it.

The alumina cement composition of the present invention contains alumina cement and α-Al ₂ O ₃ for the purpose of improving fire resistance and sinterability at high temperature. or a mixture of α-Al ₂ O _3, clinker alumina cement, α-Al ₂ O _3, and may be mixed with each grinding various additives as required, clinker, α-Al ₂ O _3,
And, it is possible to mix and pulverize various additives as required to manufacture.

Fe in the alumina cement or the alumina cement composition of the present invention (hereinafter referred to as alumina cements)
And FeO content can be reduced by using CaO raw material or Al ₂ O ₃ raw material with low iron content, or by using carbon when producing clinker by melting method such as electric furnace or reverberatory furnace. By melting in a lined furnace or adding a reducing agent such as pulverized coal to the raw material, the iron content is reduced, and the iron content is settled at the bottom of the furnace by utilizing the difference in specific gravity from the clinker, and only the supernatant A method of removing iron by tapping, a method of reducing the content of Fe or FeO 2 by melting and / or firing in a reducing atmosphere for a long time are possible.

Furthermore, when synthesizing the clinker, Si
It is possible to further improve the CO gas resistance and stabilize the color tone by adding a small amount of O ₂ and selectively dissolving iron in the glass phase.

In the present invention, it is preferable to manufacture the clinker by a melting method such as an electric furnace or a reverberatory furnace, in which iron is easily reduced and removed relatively easily, and it is most preferable to manufacture the clinker in a carbon lined electric furnace. In this case, the reduced state can be maintained by extending the melt holding time, and the iron content can be easily removed. Therefore, after melting the raw material, at least 10
It is preferable to hold the molten state for at least 30 minutes, and it is more preferable to hold at least 30 minutes. By maintaining the molten state, iron oxides such as FeO, Fe ₃ O ₄ , and Fe ₂ O ₃ are reduced and settled in the hearth due to the difference in specific gravity from calcium aluminate, and the iron content of Fe and FeO from the clinker phase is reduced. Can be separated and removed.

Further, when a reducing material is used, the raw material 10
It is possible to add about 5 parts by weight or less of the reducing agent to 0 part by weight. When a large amount of reducing agent is used, the reducing agent remains in the clinker, and when it is used as an alumina cement in an amorphous refractory, fluidity and strength development may be reduced, or shrinkage may occur.

Further, the chemical components in the alumina cements are CaO 15 to 40% by weight, Al ₂ O ₃ 60 to 85% by weight, and SiO ₂
Is less than 1% by weight, and Fe and FeO are each less than 0.1% by weight because CO resistance is excellent. The content ratios of Fe and Fe0 in the alumina cements in the present invention are each 0.1% by weight or less, more preferably 0.05% by weight or less. 0.1
If the content exceeds 10% by weight, the volume changes greatly when used in a CO atmosphere, and the color tone of the cured product may change after long-term exposure.

The Fe and FeO contents can be measured, for example, by the following method. 1 g of the sample was put into a 200 ml Erlenmeyer flask whose atmosphere was replaced with nitrogen to prevent oxidation, 50 ml of bromine-methyl alcohol was added, and the mixture was stirred in a nitrogen atmosphere for 10 minutes, filtered, washed with methyl alcohol, and the residue was filtered with a paper filter. Put it in an Erlenmeyer flask together with nitrogen, add 20 ml of 6N HCl, dissolve by heating, cool to room temperature, and add 100 ml of water, H ₂ SO ₄ , H ₃ PO ₄ , and water by weight. Add 30 ml of mixed acid mixed at a ratio of 3/3/14 and 0.5 ml of sodium diphenylamine sulfonate, and add 1/40
It is possible to measure the FeO 2 content by titrating with the specified potassium dichromate. Also, add 300 ml of the filtrate and washing solution.
In a beaker, add 20 ml of 6N HCl and concentrate for about 1 hour. Add 10 ml of HClO ₄ and dry to dryness.
l 10 ml and warm water 50 ml were added, filtered, and fixed in a 200 ml volumetric flask, and measured by atomic absorption spectrometry (AAS) at 2,483 Å
It is possible to measure Fe.

In the present invention, the mixing ratio of the mineral composition is Cu
It can be analyzed by X-ray diffraction analysis using -K α ray. As a method for quantifying the mineral composition by the X-ray diffraction method, there are a diffraction line intensity ratio measuring method, an internal standard method, a Zevine method, an X-ray diffraction peak separation method, and the like, and any method can be quantified in the present invention. The diffraction line intensity ratio measurement method referred to here is a value that relatively expresses the diffraction intensity of each mineral composition, and the internal standard method is a mixture of an internal standard substance and a sample at a fixed ratio. However, by utilizing the fact that a linear relationship is obtained between the component concentration and the diffraction line intensity ratio, a calibration curve is prepared and analyzed using a standard sample of known concentration. Also Zevi
The ne method is a method of quantifying each crystal phase by measuring an average mass absorption coefficient of a sample and a diffraction line intensity ratio and solving a simultaneous equation of order n. 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 to this, it is also possible to perform quantification by an X-ray diffraction peak separation method in which measurement is performed from the crystal or glass phase of the sample.
In the present invention, the mineral composition can be quantified by any method, but the Zevine method or the diffraction line intensity ratio measuring method, which is simple and highly accurate, is preferable.

The specific surface area (brain value) of the alumina cement of the present invention can be measured by the method described in JIS R2521, and is an important control point because it is involved in fluidity, curability and strength development. Therefore, the particle size of the crushed clinker has a Blaine value of 2,000 to 10,000 cm ² / g.
Is preferable, and 4,000 to 8,000 cm ² / g is more preferable. 2,00
If it is less than 0 cm ² / g, the hydration activity as an alumina cement is low, and the strength development may be deteriorated, or curing failure may occur.If it exceeds 10,000 cm ² / g, the hydration activity becomes large. If it is too low, the fluidity may decrease and the pot life after water injection may not be secured.

[0021] The α-Al ₂ O ₃ blended with alumina cement, a purified alumina obtained by calcining a highly purified treated aluminum hydroxide by the buyer processes such rotary kiln or the like, the Al ₂ O ₃ It is a high-purity alumina containing 90% by weight or more, and is generally called high-purity alumina, Bayer alumina, easy-sintering alumina, or light-burning alumina.

Although the purity of α-Al ₂ O ₃ has never been higher, the purity of α-Al ₂ O ₃ is 98% by weight or more of Al ₂ O _{3 in the} case of alumina produced by a usual Bayer process. It is sufficient because it can be secured. 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 baked using as a raw material and the sodium content is removed. The soluble Na ₂ O content is preferably 0.1% by weight or less, more preferably 0.05% by weight or less. Soluble Na
_{When the amount of 2} O is large, when the alumina cement composition is used, Na ions act as a curing accelerator, and the pot life and fluidity may not be secured. Further, the total Na ₂ O content is preferably low, preferably 0.5% by weight or less, and more preferably 0.35% by weight or less, a low sodium type. When the total amount of Na ₂ O is large, when it is made into alumina cement, the fluidity and fire resistance may be reduced, or it may shrink at high temperatures. Soluble SO ₃ is
Most of them are contained in α-Al ₂ O ₃ from fuels such as heavy oil and coal when firing aluminum hydroxide, and the amount is 0.05 wt% or less. It is preferable in terms of characteristics. If the amount of soluble SO ₃ is large, the hardening of alumina cement may be delayed.

In the present invention, the BET specific surface area of α-Al ₂ O ₃ is also important, preferably 0.3 to 0.8 m ² / g, and 0.4 to 0.7.
m ² / g is more preferred. If the BET specific surface area is less than 0.3 m ² / g, strength development at high temperature may decrease when used for amorphous refractories, and if it exceeds 0.8 m ² / g, pot life as an alumina cement composition In some cases, liquidity cannot be secured.

In the present invention, the BET specific surface area is 0.3 to 0.8.
It is preferable to use m ² / g of α-Al ₂ O _3, which has a BET specific surface area of 0.4 to 0.7 m ² / g and contains soluble Na ₂ O as a chemical component.
Α-Al ₂ O with 0.1 wt% or less and soluble SO ₃ 0.05 wt% or less
More preferably ₃ is used.

The amount of α-Al ₂ O ₃ used is preferably 10 to 50 parts by weight, more preferably 20 to 30 parts by weight, based on 100 parts by weight of the alumina cement composition. If the amount of α-Al ₂ O ₃ used 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 strength development at high temperatures is sufficient. Not always.

Further, in the present invention, for the purpose of improving the fluidity of alumina cements and amorphous refractories using the same, they are usually blended with amorphous refractory, for example, refractory; 33-5
9, p3 to 7,1981, refractory materials; 3-393, p31 to 34,1981, and refractory materials; 40-5, p270 to 278,1988, etc., such as curing retarders and curing accelerators. It is possible to use additives and fluidizing agents in combination.

Examples of the curing retarder include carboxylic acids, alkali metal carbonates, boric acids, polyacrylic acids, polymethacrylic acids, and phosphoric acids, among which carboxylic acids or carboxylic acids of alkali salts thereof are preferably used. . Here, the carboxylic acids are oxycarboxylic acids, specifically, citric acid, gluconic acid,
Examples thereof include tartaric acid, succinic acid, lactic acid, malic acid, and salicylic acid, or their alkali salts such as sodium salt, potassium salt, and calcium salt. Among these, use of citric acid or an alkali salt thereof, particularly sodium citrate or potassium citrate, is preferred. The purity of the carboxylic acids is not particularly limited, but currently industrially purified carboxylic acids can be used, and the purity of the target carboxylic acids is preferably about 80% by weight or more. Among them, citric acid containing 0.05% by weight or less of sulfate as an impurity or a salt thereof, or citric acid having a pH of 7 to 10 of a 1% by weight concentration aqueous solution at 20 ° C. or a salt thereof is It is preferable because it is excellent.

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

The boric acid refers to boric acid or its alkali salt. Boric acid is also called boric acid, orthoboric acid, or orthoboric acid, is represented 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, a method in which sulfuric acid is added to a raw ore of boric acid for thermal decomposition, boric acid is liberated, separated and extracted, and then purified is performed. 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 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 acids is not particularly limited, but it is possible to use boric acid which is currently industrially refined, and boric acid having a BO ₄ content of 80% by weight or more. preferable.

Examples of polyacrylic acids include polyacrylic acid and salts thereof such as sodium polyacrylate, potassium polyacrylate, and ammonium polyacrylate. Among them, performance, price, and availability are available. It is most preferable to use sodium polyacrylate because it is easy and easy to handle.

Examples of the polymethacrylic acids include polymethacrylic acid and salts thereof such as sodium polymethacrylate, potassium polymethacrylate, and ammonium polymethacrylate. Among them, the performance,
It is most preferable to use sodium polymethacrylate because of its price, availability and handling.

Examples of the phosphoric acids include hexametaphosphoric acid, tripolyphosphoric acid, pyrophosphoric acid and alkali salts thereof.

Examples of the curing accelerator include hydroxides such as sodium hydroxide, potassium hydroxide and calcium hydroxide, and water-soluble lithium compounds such as lithium carbonate, lithium chloride and lithium citrate. Among them, the use of a water-soluble lithium compound is preferable from the viewpoint of strong curing acceleration action.

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

The fluidizing agent is an admixture containing a surfactant having excellent cement dispersibility as a main component, and is generally a salt of naphthalenesulfonic acid formalin condensate (naphthalene type), melamine resin sulfonic acid formalin condensate. The salts thereof (melamine type), the salts of olefin / maleic acid copolymers (carboxylic acid type) and the like can be used. Specifically, the sodium salt of β-naphthalenesulfonic acid high condensation product, creosote oil sulfonic acid can be used. Examples thereof include sodium salts of condensates, sodium salts of low β-naphthalenesulfonic acid condensates, and polyoxyethylene nonylphenyl ether. Although the amount of the fluidizing agent used is not particularly limited, it is preferably 5 parts by weight or less with respect to 100 parts by weight of the amorphous refractory composed of the alumina cement and the refractory aggregate.

The method of mixing the additives and the fluidizing agent is not particularly limited, and the additives and the like are mixed in a predetermined ratio, and alumina cements which have been crushed in advance and V
Type blender, corn blender, Nauta mixer, pan mixer, and omni mixer or the like, or after mixing alumina cement and additives in a predetermined ratio, vibration mill, tube It is possible to mix and grind with a grinder such as a mill, a ball mill and a roller mill.

In the present invention, additives such as 100 to 400 are added.
Heat at a temperature of ℃ and mix with alumina cements,
Alternatively, a method of heating a mixture of additives and the like and alumina cements together is possible. As a heating method, a method of heating at the same time as crushing, a method of heating with hot air during transportation, a method of heating a transportation machine, a method of heating during storage, and the like are possible. These additives are ICP,
ICPA, GC-MS, NMR, HPLC, and FT-
It is possible to specify the type and the quantitative ratio by instrumental analysis such as IR, chelate analysis, activation analysis and the like.

The water used in the present invention is particularly limited.
Not tap water, industrial water, natural water, river water, etc.
Water used for general concrete can be used
But Na ⁺, K⁺, Mg²⁺, Ca²⁺, And Cl^-Soluble ingredients such as
Less water is preferred. The amount of water used is the target irregular shape
Appropriately determined by the refractory and not particularly limited
No, but breathing or strong when the amount of water used increases
The expression may be reduced. For that reason,
For the irregular refractory to be processed, the irregular refractory is usually 100 weight.
It is preferably 2 to 20 parts by weight with respect to parts. In general, JI
Flow value measured by the method described in S R 2521 is 130 to 240 mm
It is preferable to add water so that

The refractory aggregate used in the present invention preferably has a small content ratio of Fe and FeO as chemical components, and in particular, it is preferable to blend Fe and FeO at 5.0% by weight or less in order to reduce CO gas resistance. It is preferable from the aspect.

As the refractory aggregate used in the present invention, the refractory aggregate which is usually used for an irregular shaped refractory can be used. Specific examples include magnesia, magnesia spinel, alumina, carbon, and ultrafine powder, and others, fused silica, calcined mullite, chromium oxide,
Bauxite, andalusite, sillimanite, chamotte, silica stone, loastone, clay, zircon, zirconia,
Dolomite, perlite, vermiculite, brick waste,
Pottery waste, silicon nitride, boron nitride, silicon carbide, silicon nitride iron, etc. can be used. Particularly, in the amorphous refractory of the present invention, from the aspect of CO gas resistance and corrosion resistance, magnesia aggregate, magnesia spinel aggregate, alumina aggregate, carbon aggregate, ultrafine powder, and chamotte or silicon carbide. It is preferable to mix one or more kinds of refractory aggregates selected from such aggregates. Further, when used in the molten steel process of the steel manufacturing process, from the viewpoint of slag permeation suppression, it is preferable to use a combination of magnesia aggregate and alumina aggregate or a combination of magnesia spinel aggregate and alumina aggregate, the hot metal process When it is used for, it is preferable to use an alumina-based aggregate such as fused alumina or sintered alumina, a carbon-based aggregate, ultrafine powder, and an additive together.

Here, the magnesia aggregate is a calcination obtained by calcining magnesium hydroxide, magnesium carbonate extracted from seawater by the seawater method, magnesite which is natural magnesia, natural magnesium carbonate and the like in a rotary kiln or the like. The fused magnesia clinker is an electrofused 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 electrofused magnesia clinker is crushed to a predetermined size and sieved. The MgO purity is 80
When it is used in an irregular shaped refractory, it is preferable that it has a weight percent or more because of its excellent corrosion resistance, and it is preferable that impurities such as SiO ₂ and TiO ₂ are small, and the purity of MgO is 95 weight% or more.
CaO 2 wt% or less, SiO ₂ 0.5 wt% or less, and B ₂ O ₃
Is preferably 0.5% by weight or less because of its excellent corrosion resistance. Specifically, molten magnesia, sintered magnesia, natural magnesia, and light-burning magnesia can be used, in addition to these, spinel-coated magnesia, magnesia containing magnesium titanate in the grain boundaries, and magnesia particles on the surface. Magnesia that produced calcium aluminate, special magnesia with high purity, high bulk density and coarse crystal grains used for basic bricks, and magnesia zirconia with improved heat spalling resistance were crushed Special magnesia can also be used.

The magnesia spinel aggregate is a mixture of MgO raw material such as magnesium hydroxide and calcined magnesia and Al ₂ O ₃ raw material such as aluminum hydroxide and calcined alumina in a predetermined ratio. , A magnesia spinel clinker that has been reacted and calcined at a temperature of about 1,800 to 1,900 ° C. using a calcination device such as a rotary kiln, and a magnesia spinel clinker melted in a melting device such as an electric furnace. A magnesia spinel clinker, which is a mixture of a calcined material and a melted material, is crushed to a predetermined size and sieved. Specific examples thereof include molten magnesia spinel and sintered magnesia spinel. Mg in magnesia spinel clinker
O / Al ₂ O ₃ molar ratio is preferably from 0.1 / 1 to 1/1, 0.
2/1 to 0.4 / 1 are more preferable in terms of excellent durability when compounded with an irregular shaped refractory.

The alumina-based aggregate is obtained by melting and / or calcining an Al ₂ O ₃ raw material such as aluminum hydroxide or calcined alumina with a melting device such as an electric furnace or a calcination device such as a rotary kiln. It was crushed to the size of and sieved, and the mineral composition was α-Al ₂ O ₃ or γ-Al ₂ O ₃
And aluminum oxide, which are referred to as fused alumina, fused alumina, sintered alumina, calcined alumina, and easily sintered alumina. Usually Al ₂ O ₃
It is most preferable to use α-Al ₂ O ₃ containing 90% by weight or more. Specific examples thereof include fused alumina, sintered alumina, light burned alumina, and easily sintered alumina. Also, obtained by melting alumina and zirconia clinker,
It is also possible to use alumina / zirconia clinker having improved heat-resistant spalling properties.

As the carbonaceous aggregate, oil pitch,
Examples include tar and scaly graphite.

The refractory aggregate is a mixture of various particle sizes depending on the required physical properties, and the particle size of the refractory aggregate is usually 5 to 3 mm,
4-1mm, 3-1mm, 1mm lower, 200 mesh lower, and 32
It is divided into 5 meshes (45 μm) and so on.

In the present invention, it is possible to use, as the refractory aggregate, ultrafine powder having a fine particle size. Here, the ultrafine powder is a refractory fine powder in which 80% by weight or more of particles having a particle diameter of 10 μm or less and an average particle diameter of 1 μm.
Below, those having a specific surface area of 10 m ² / g or more as measured by the BET method are preferable because they have excellent fluidity and high strength when compounded with an amorphous refractory material. Specifically, silica fume,
Inorganic fine powders such as colloidal silica, light burned alumina, easily sintered alumina, amorphous silica, zircon, silicon carbide, silicon nitride, chromium oxide, and titanium oxide can be used. Among them, silica fume, colloidal silica, It is preferable to use fine powder of easily sintered alumina. In particular, silica fume used for low cement castable is important because the pH of the slurry when it is slurried affects the dispersibility.
From weak acidity to acidity, it is particularly preferable from the viewpoint that the pot life can be secured.

The amount of the refractory aggregate to be used should be appropriately determined depending on the construction site and is not particularly limited, but 50 to 99 parts by weight is preferable in 100 parts by weight of the irregular refractory material, and the fluidity, From the viewpoint of curability and strength development, 65 to 85 parts by weight is more preferable. Low cement castables that use ultrafine powder as a fire-resistant aggregate
A compounding amount of 6 parts by weight, 94 to 98 parts by weight of refractory aggregate, and 5 parts by weight or less of silica fume is preferable from the viewpoint of ensuring fluidity and pot life.

The method for producing the amorphous refractory material of the present invention is not particularly limited, but according to the ordinary method for producing an amorphous refractory material, the respective raw materials are blended in a predetermined ratio and V
Type blender, corn blender, nauter 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 into the kneader when performing kneading at a predetermined ratio.

Further, the amorphous refractory material of the present invention contains metal powder such as metal aluminum or silicon alloy, organic fiber such as vinylon fiber or polypropylene, for the purpose of preventing explosion which tends to occur when the cured product is dried. A nitrogen-containing gas product and an explosion-proof agent such as dextrin may be added as required. The amount of anti-explosive agent used should be appropriately determined according to the desired explosion resistance and cannot be uniquely determined, but generally it is 0.05 to 5 with respect to 100 parts by weight of the amorphous refractory. It is possible to blend in parts by weight.

[0050]

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

Example 1 A CaO raw material and an Al ₂ O ₃ raw material α were blended and melted in an electric furnace.
After maintaining the molten state for the molten holding time shown in Table 1 and performing low iron differentiation treatment, the molten material is rapidly cooled with high pressure cooling air,
CaO 33.1% by weight, Al ₂ O ₃ 65.8% by weight, SiO ₂ 0.8% by weight,
And, clinker having less than 0.1% by weight of TiO ₂ and chemical composition of iron shown in Table 1 and having mineral composition of CA and CA ₂ was synthesized. The synthesized clinker was pulverized by an alumina lining filled alumina ball vibrating mill manufactured by Chuo Koki Co., Ltd. to produce an alumina cement of the present invention having a Blaine value of 4,800 cm ² / g. Amorphous refractory material 100 containing 15 parts by weight of manufactured alumina cement and 85 parts by weight of refractory aggregate a
After adding 9.5 parts by weight of water to the parts by weight and kneading with a mixer for 5 minutes, flow value as fluidity, curing time, curing strength and dry strength as room temperature strength, firing strength as high temperature strength, CO resistance, and The change in color tone upon exposure was measured. All measurements were carried out in a constant temperature room at 20 ° C. The results are also shown in Table 1.

<Materials used> CaO raw material: Commercial quicklime Al ₂ O ₃ raw material α: High-purity alumina produced by the Bayer method, commercial product, Al ₂ O ₃ purity 99% by weight, average particle diameter 70 μm Fire-resistant aggregate a: Electrofused alumina, commercial product, particle size 5 to 3 mm 40% by weight, particle size 3 to 1 mm 45% by weight, 1 mm down 10% by weight, and 45
5% by weight under μm

<Measurement method> Mineral composition: X-ray diffractometry was used to measure the presence or absence of diffraction lines for each mineral composition. Chemical analysis: FeO content was a 200 ml triangle obtained by substituting 1 g of the sample with nitrogen to prevent oxidation. Put in a flask, bromine-
Add 50 ml of methyl alcohol, stir in a nitrogen atmosphere for 10 minutes, filter, wash with methyl alcohol, put the residue in an Erlenmeyer flask with filter paper, replace with nitrogen, and then add 6N.
Add 20 ml of HCl, heat to dissolve, cool to room temperature,
Further, 100 ml of water, H ₂ SO ₄ , H ₃ PO ₄ , and 30 ml of a mixed acid prepared by mixing water in a weight ratio of 3/3/14, and 0.5 ml of sodium diphenylamine sulfonate were added to give a 1 / 40N ratio. The FeO content was measured by titration with potassium dichromate. The Fe content was determined by placing the filtrate and the washing solution in a 300 ml beaker, adding 6N HCl (20 ml) and concentrating for about 1 hour.
Furthermore, 10 ml of HClO _{4 was} added to dryness, 10 ml of 6N HCl and 50 ml of warm water were added, filtered, and fixed in a volumetric flask of 200 ml, and measured by atomic absorption spectrometry (AAS) at 2,483Å Flow value: fluidity Evaluation, after leaving the kneaded product in the constant temperature chamber at 20 ° C for a predetermined time, and then tapping it 15 times. Curing time: Using a temperature recorder, the exothermic temperature from pouring water when leaving the kneaded product in the constant temperature chamber at 20 ° C Time to reach the maximum Curing strength: Room temperature strength, compressing strength after putting the kneaded product in a 4 × 4 × 16 cm mold for 24 hours in a 20 ° C. constant temperature Drying strength: Room temperature strength, after 24 hours curing, Furthermore, 110 ℃
Compressive strength after being dried for 24 hours at: Firing strength: High temperature strength, dried at 110 ° C, put in a siliconit electric furnace, baked at 1,000 ° C for 3 hours, and then allowed to cool to room temperature Compressive strength CO gas resistance: 800 Visual observation of the presence or absence of cracks in the cured product left in a CO gas stream heated to ℃ for 3 hours, and the length change was measured using a length change meter Color change: Exposure of the cured product for 1 month after curing Visually check if there is any change in color condition when

[0054]

[Table 1]

As shown in Table 1, the amorphous refractory containing the alumina cement of the present invention has good CO gas resistance,
There are no cracks, little change in length, and no change in color tone after long-term exposure.

Example 2 CA, CA ₂ and C ₁₂ A ₇ were individually synthesized, and TiO ₂
Less than 0.1 wt%, Fe 0.01 wt%, and FeO 0.02 wt%
Example 1 except that the alumina cement was used in which other chemical components and mineral compositions were mixed as shown in Table 2.
I went the same way. The results are also shown in Table 2.

[0057]

[Table 2]

As shown in Table 2, the amorphous refractory containing the alumina cement of the present invention has good CO gas resistance,
There are no cracks, little change in length, and no change in color tone after long-term exposure.

Example 3 Experiment No. 1 of Example 1 so that the chemical components shown in Table 3 were obtained.
Α-Al ₂ O ₃ was added to the clinker of 3, and the same procedure was performed as in Example 1 except that an alumina cement composition having a Blaine value of 4,800 cm ² / g was pulverized. The results are also shown in Table 3. For comparison, the same procedure was performed using commercially available alumina cement. The results are also shown in Table 3.

<Materials used> AC-1: Alumina cement, mineral composition CA, CaO 36.5
% By weight, Al ₂ O ₃ 54.0% by weight, SiO ₂ 4.0% by weight, TiO ₂ 3.5
Wt%, Fe 1.1 wt%, FeO 1.3 wt%, Blaine value 4,85
0 cm ² / g AC-2: Alumina cement, mineral composition CA, CA ₂ , and α-Al ₂ O ₃ , CaO 25.0% by weight, Al ₂ O ₃ 74.5% by weight, SiO ₂
0.5% by weight, TiO ₂ less than 0.1% by weight, Fe 0.06% by weight, Fe
O0.2% by weight, Blaine value 4,780 cm ² / g AC-3: Alumina cement, mineral composition CA, CA ₂ , C
₁₂ A ₇ , and α-Al ₂ O ₃ , CaO 26.5% by weight, Al ₂ O ₃ 73.0% by weight, SiO ₂ 0.5% by weight, TiO ₂ less than 0.1% by weight, Fe 0.2% by weight, FeO 0.3% by weight, Blaine value 6,200 cm ² / g

[0061]

[Table 3]

As shown in Table 3, the amorphous refractory containing the alumina cement composition of the present invention is more resistant to CO than the conventional amorphous refractory containing commercially available alumina cement.
It has good gas properties, no cracks, little change in length, and no change in color tone after long-term exposure.

Example 4 A melt holding time of 30H, CA and CA ₂ as mineral compositions, CaO 33.2% by weight, Al ₂ O ₃ 65.7% by weight, SiO ₂ 0.8% by weight, and TiO ₂ less than 0.1% by weight. The procedure of Example 1 was repeated, except that the alumina cement having the iron content shown in Table 4 and having the Blaine value shown in Table 4 was used. The results are also shown in Table 4.

[0064]

[Table 4]

As shown in Table 4, the amorphous refractory containing the alumina cement of the present invention has good CO gas resistance,
There are no cracks, little change in length, and no change in color tone after long-term exposure.

Example 5 Using the Al ₂ O ₃ raw material β, the chemistry of the iron components shown in Table 5 was calculated using CaO 36.5% by weight, Al ₂ O ₃ 54.1% by weight, SiO ₂ 3.9% by weight, and TiO ₂ 3.5% by weight. The same procedure as in Example 1 was performed, except that the components and a clinker having a mineral composition of CA and CA ₂ were synthesized.
The results are also shown in Table 5.

<Material used> Al ₂ O ₃ raw material β: bauxite

[0068]

[Table 5]

As shown in Table 5, the amorphous refractory containing the alumina cement of the present invention has good CO gas resistance,
There are no cracks, little change in length, and no change in color tone after long-term exposure.

Example 6 Melt holding time of 30 hours, CA and CA ₂ were contained as mineral compositions, and the chemical components were CaO 31.8% by weight, Al ₂ O ₃ 67.4% by weight, Si
Alumina cement containing less than 0.8% by weight of O ₂ and less than 0.1% by weight of TiO ₂ was blended with α-Al ₂ O ₃ having a BET specific surface area of 0.6 m ² / g as shown in Table 6 and pulverized in the same manner as in Example 1. Then, the alumina cement composition of the present invention was manufactured. Example 1 was repeated except that the produced alumina cement composition was used instead of alumina cement. The results are also shown in Table 6.

[0071]

[Table 6]

As shown in Table 6, the amorphous refractory containing the alumina cement composition of the present invention has good CO gas resistance, no cracks, little change in length, and long-term exposure. There is no change in color tone.

Example 7 Alumina cement 70 with 0.02 wt% Fe and 0.04 wt% FeO
Parts by weight and 30 parts by weight of α-Al ₂ O ₃ were mixed to produce an alumina cement composition having a Blaine value shown in Table 7. Example 1 was repeated except that the produced alumina cement composition was used instead of alumina cement. Table 7 shows the results
It is described together.

[0074]

[Table 7]

As shown in Table 7, the amorphous refractory containing the alumina cement composition of the present invention has good CO gas resistance, no cracking, little change in length, and long-term exposure. There is no change in color tone.

Example 8 Fe 0.07% by weight FeO 0.22% by weight, Blaine value 10,000
Using an alumina cement composition in which 70 parts by weight of cm ² / g of alumina cement and 30 parts by weight of α-Al ₂ O ₃ were mixed, an alumina cement composition deironed by an electromagnet manufactured by Nippon Magnetic Co., Ltd. of 6,000 Gauss was manufactured. . Example 1 was repeated except that the produced alumina cement composition was used instead of alumina cement. Table 8 shows the results.

[0077]

[Table 8]

As shown in Table 8, by further deferring the alumina cement composition of the present invention, CO gas resistance is good, cracks are not generated, and the change in length can be reduced.

[0079]

INDUSTRIAL APPLICABILITY The present invention provides an alumina cement, an alumina cement composition, and an amorphous refractory material using the same, which has a CO gas resistance not found in conventional products and a color tone of the cured product when the cured product is exposed for a long period of time. It has characteristics that change little, especially when used in combination with refractory aggregates for irregular shaped refractories, the length change is small even if left in CO gas, and it has excellent volume stability, mainly in blast furnaces. Can be used for. Further, there is little change in color tone after long-term exposure, which is suitable for use as a civil engineering / construction material.

Claims (3)

[Claims] 1. An alumina cement characterized in that Fe and FeO as chemical components are each 0.1 wt% or less. 2. Alumina cement and α-A according to claim 1.
An alumina cement composition containing l ₂ O ₃ . 3. An amorphous refractory material obtained by blending the alumina cement according to claim 1 or the alumina cement composition according to claim 2 with a refractory aggregate.