JP3310099B2 - Alumina cement and amorphous refractories using it - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention can be used for refractories such as furnace materials related to iron and steel, and alumina cement having two or more particle size distributions, particularly excellent workability even in a working atmosphere of 30 ° C. or more. The present invention relates to an alumina cement exhibiting heat resistance, strength development, heat resistance, and early strength, and an amorphous refractory using the same.

[0002]

2. Description of the Related Art Conventionally, alumina cement has been
In the construction in a high-temperature atmosphere of 30 ° C. or more, there were problems such as poor workability, difficulty in construction, poor strength development, peeling and cracking.

[0003] In order to improve these, an alumina cement composition comprising a hydroxycarboxylate and the like, an alumina cement composition comprising an inorganic carbonate and the like, and a polymethacrylic acid and the like are incorporated into alumina cement. Alumina cement containing various additives such as alumina cement and alumina cement having a square particle shape have been proposed (Japanese Patent Publication No. 50-28090, Japanese Patent Publication No. 55-45507). JP-B-56-22822, JP-B-57-2
1499, Japanese Patent Publication No. 60-54897, Japanese Patent Publication No. 60-54898, and Japanese Patent Publication No. 63-384).

[0004] However, there has been a problem that the alumina cement to which such additives are added cannot sufficiently satisfy workability and strength development under high-temperature construction.

The present inventor has conducted various studies to solve the above-mentioned problems, and as a result, an alumina cement obtained by combining powders having an average particle size of a particle size distribution in two or more particle size ranges has been developed.
The inventors have completed the present invention by overcoming the problems of the prior art and finding that they are excellent in workability and strength development.

[0006]

That is, the present invention provides CaO.Al ₂ O ₃ as a hydraulic component as a main component and has a particle size range of 2 to less than 8 μm, a particle size range of less than 2 μm and / or a particle size of 8 μm or more. Alumina cement having a particle size distribution peak in a particle size range, and a powder contained in one of the particle size ranges is 30% by weight or more. It is an amorphous refractory contained.

Hereinafter, the present invention will be described in detail.

The alumina cement used in the present invention uses bauxite, high alumina, refined alumina or the like as an alumina source, and limestone or quicklime as a calcia source. And clinker obtained by melting or baking in a rotary kiln or the like.

The alumina cement used in the present invention is mainly composed of CaO.Al ₂ O ₃ as a hydraulic component. Specifically, CaO.Al ₂ O ₃ and CaO.Al ₂ O ₃ are used. Al ₂ O ₃ and CaO
The 2Al ₂ O _3, and, the CaO · Al ₂ O ₃ and 12CaO · 7Al ₂ O _3, furthermore, contain CaO · Al ₂ O ₃ and CaO · 2Al ₂ O ₃ and 12CaO · 7Al ₂ O ₃ Alumina Cement.

The alumina cement used in the present invention has a particle size distribution peak in a particle size range of 2 to less than 8 μm, a particle size range of less than 2 μm and / or a particle size range of 8 μm or more. In the present invention, the particle size corresponding to the peak of the particle size distribution is indicated as the average particle size Dp50. Also,
The powder contained in one of the particle size ranges is 30% by weight or more, preferably 40% by weight or more. 30% by weight
If it is less than 1, the effect of improving the fluidity and strength can not be expected.

Here, as the particle size distribution measuring method, a general particle size distribution measuring method such as a laser diffraction method, a light scattering method, a photon correlation method and a sedimentation method can be used.

In the present invention, the method of pulverizing clinker of alumina cement is not particularly limited.
For example, a general mill such as a vibration mill, a roller mill, a tube mill, a ball mill, a tower mill, a jet mill, and an impact mill can be used, and a separator,
It is preferable to use a general classifier such as an aspirator and a cyclone in combination.

In the present invention, furthermore, hydroxycarboxylic acids or salts thereof such as citric acid, gluconic acid, tartaric acid, malic acid and salicylic acid or sodium, potassium and calcium salts thereof, polyacrylic acid or salts thereof , Polymethacrylic acid or a salt thereof, and one or more organic acids selected from the group consisting of a methacrylic acid-acrylic acid copolymer or a salt thereof, and the like. The amount of the organic acid used is preferably 0.1 to 10 parts by weight based on 100 parts by weight of the alumina cement. 0.1
If the amount is less than 10 parts by weight, the workability tends to decrease.

A carbonate such as potassium carbonate, sodium carbonate, sodium hydrogencarbonate, and potassium hydrogencarbonate;
One or more inorganic salts selected from the group consisting of sodium tripolyphosphate, sodium hexametaphosphate, sodium acid hexametaphosphate, aluminum phosphate, sodium borate, and boric acid can be used as appropriate. . The amount of the inorganic salt used is preferably 0.1 to 10 parts by weight based on 100 parts by weight of the alumina cement. 0.1
If the amount is less than 10 parts by weight, the workability tends to decrease.

The refractory aggregate used in the present invention may be any refractory aggregate used for irregular-shaped refractories. Specifically, molten magnesia, sintered magnesia, natural magnesia, And magnesia such as lightly burned magnesia, magnesia spinel such as fused magnesia spinel and sintered magnesia spinel, and alumina such as fused alumina, sintered alumina, lightly burned alumina, and easily sintered alumina, and other fused silica and calcined mullite , Chromium oxide,
Bauxite, andalusite, sillimanite, chamotte, quartzite, raw stone, clay, zircon, zirconia,
Dolomite, perlite, vermiculite, brick kuzu,
Pottery, silicon nitride, boron nitride, silicon carbide and silicon iron nitride can be used. In particular, in the present invention, it is preferable to use one or more types of refractory aggregates selected from magnesia, magnesia spinel, and alumina from the viewpoint of corrosion resistance, durability, and fire resistance. Also,
From the viewpoint of suppressing slag penetration, a combination of magnesia and alumina, or a combination of magnesia spinel and alumina is preferable.

Here, magnesia is Mg (OH) ₂ extracted from seawater by the seawater method, magnesia carbonate, magnesite which is natural MgO, and sintered magnesia clinker obtained by firing natural magnesia carbonate in a rotary kiln or the like. And an electrofused magnesia clinker obtained by melting the sintered magnesia clinker in an electric furnace or the like, crushed to a predetermined size and sieved. Among them, those having a magnesia purity of 80% by weight or more are preferable in terms of excellent corrosion resistance when used for amorphous refractories, those having few impurities such as SiO ₂ and TiO ₂ are preferable, and the purity of MgO is 95% by weight. not less than, CaO content of from 2 wt% or less, the content of SiO ₂ is 0.5 wt% or less, magnesia content below 0.5% by weight of B ₂ O ₃ is preferable from the viewpoint of excellent corrosion resistance. In addition, magnesia coated with spinel, magnesia containing magnesium titanate at the grain boundaries, magnesia formed with calcium aluminate on the surface of magnesia particles, high purity, high bulk density, and coarseness used for basic bricks Special magnesia clinker with crystal grains, and
Special magnesia such as magnesia and zirconia clinker with improved heat spalling properties can also be used.

The magnesia spinel is obtained by mixing a MgO source such as magnesium hydroxide or calcined magnesia and an Al ₂ O ₃ source such as aluminum hydroxide or calcined alumina so as to have a predetermined ratio, and using a rotary kiln. Using a sintering device such as, a reaction and sintering at about 1,800 to 1,900 ° C. to form a spinel clinker, a melted magnesia spinel melted by a melting device such as an electric furnace, crushed to a predetermined size and sieved, Furthermore, those obtained by mixing these baked and molten materials are also used. The weight ratio of MgO / Al ₂ O ₃ of magnesia spinel is preferably 1/1 to 0.1 / 1, when the 0.4 / 1 to 0.2 / 1 is blended in monolithic refractories, and more preferable from the viewpoint of excellent durability.

The alumina used in the present invention is a material obtained by sintering and / or melting an alumina source such as aluminum hydroxide or calcined alumina by a sintering device such as a rotary kiln or a melting device such as an electric furnace. It is crushed to size and sieved, and the mineral composition is α-
Aluminum oxide, such as Al ₂ O ₃ or β-Al ₂ O _3, which is called sintered alumina, calcined alumina, or easily sintered alumina, of which 90% by weight of Al ₂ O ₃
Most preferably, α-Al ₂ O ₃ is used. In the present invention, it is also possible to use an alumina / zirconia clinker which is obtained by melting alumina and zirconia clinker and has improved heat-resistant spalling property.

The refractory aggregate is usually 5 to 3 mm, 3 to 1 mm,
Those having a size of 1 to 200 mesh, under 200 mesh, under 325 mesh and the like are blended and used according to required physical properties.

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 size of 10 μm or less make up 80% by weight or more, have an average particle size of 1 μm or less, and have a specific surface area of 10 m ² / g or more by a BET method. Is preferred from the viewpoint of ensuring flowability and exhibiting high strength when blended 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 is preferred.

In the present invention, the mixing ratio of the refractory aggregate is
It should be determined appropriately by the construction site, but is not particularly limited, alumina cement, or a total of 100 parts by weight of alumina cement composition and a refractory aggregate blended with alumina cement with organic acids and inorganic salts. And 99.
The content is preferably 5 to 50 parts by weight, and more preferably 98 to 85 parts by weight in terms of corrosion resistance and strength development.

Further, the adjustment of the particle size of the refractory aggregate is determined by the intended physical properties of the amorphous refractory, and is not particularly limited.
2-15 alumina cement or alumina cement composition
5 to 20 parts by weight of sintered magnesia having a particle size of less than 1 mm and the remainder being fused alumina and / or sintered alumina having a particle size of 1 to 10 mm, and 2 to 15 parts by weight of alumina cement or alumina cement composition Parts, magnesia spinel having a particle size of 1 mm or less, 5 to 20 parts by weight, the remainder using fused alumina and / or sintered alumina having a particle size of 1 to 10 mm, good fluidity, high strength development, Further, it is preferable because erosion by slag is small.

[0024]

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

Example 1 High-purity alumina was used as an alumina source, and high-purity calcium carbonate was used as a calcia source. Each raw material was blended so that the mineral composition in the product became a predetermined ratio, and calcined in a kiln. To produce clinker. The clinker was pulverized with a vibration mill to prepare an alumina cement as shown in Table 1. That is, the particle size range of less than 2μ was I, the particle size range of 2 to less than 8μ was II, and the particle size range of 8μ or more was III, and the average particle size Dp of each particle size distribution and the amount of powder of each particle size distribution were measured. 20 parts by weight of this alumina cement was mixed with 80 parts by weight of refractory aggregate as a refractory aggregate, and kneaded at a water / (alumina cement + refractory aggregate) ratio of 9% to produce an amorphous refractory. The flow values at 20 ° C. and 30 ° C. and the heat generation time were measured. The results are also shown in Table 2.

<Materials used> Refractory aggregate α: Sintered alumina manufactured by Showa Denko KK, particle size 3,360-
27 parts by weight of 1,190μ, 16 parts by weight of 1,190 to 590μ, 590 to 29
7μ is 16 parts by weight, 297μ is 14 parts by weight, and 44μ is 7 parts by weight

<Test Method> Flow value: According to JIS R 2521, a flow cone is placed at a predetermined position in the center of the flow table, and a castable is filled therein to smooth the surface. Next, the flow cone was removed upward, and the diameter of the castable spread was measured in two directions, that is, the longest diameter and the diameter perpendicular thereto.
The average was defined as a flow value in mm. Heating time: Put a poly-beaker containing an amorphous refractory into an insulated container, insert a resistance thermometer, measure the heating time with a recorder, and start kneading until the heating curve reaches the heat generation peak time. The time was defined as the heat generation time. Curing strength: Measure flexural strength and compressive strength after curing for 24 hours according to JIS R 2553 Dry strength: Measure flexural strength and compressive strength after drying at 110 ° C according to JIS R 2553

[0028]

[Table 1]

[0029]

[Table 2]

As is clear from the table, when the alumina cement of the present invention was used, the fluidity was good and an appropriate heat generation time was obtained.

Example 2 The same procedure as in Example 1 was carried out except that alumina cement having an average particle size changed as shown in Table 3 was used. The results are also shown in Table 3.

[0032]

[Table 3]

As is clear from the table, an amorphous refractory using alumina cement having an average particle size distribution in two or more particle size ranges and one of the particle size distribution powders being 30% by weight or more. Has good fluidity and an appropriate heat generation time.

Example 3 The same procedure as in Example 1 was carried out except that the type of the refractory aggregate was changed as shown in Table 4 using the alumina cement with the alumina cement symbol b in Table 1. The results are also shown in Table 4.

<Materials> Refractory aggregate β: commercially available Otabi chamotte, particle size 3,360 to 1,190
μ is 28 parts by weight, 1,190 to 590μ is 15 parts by weight, 590 to 297μ is
A mixture of 16 parts by weight, 15 parts by weight under 297 μ and 6 parts by weight of 44 μm sintered alumina manufactured by Showa Denko KK: Refractory aggregate γ: Spinel manufactured by Sumitomo Chemical Co., Ltd., particle size 3,360 to 1,190
μ is 30 parts by weight, 1,190-590μ is 15 parts by weight, 590-297μ is
A mixture of 15 parts by weight, 15 parts by weight at 297μ and sintered alumina manufactured by Showa Denko KK, and 5 parts by weight at 44μ

[0036]

[Table 4]

As is clear from the table, when the alumina cement composition of the present invention is used, the fluidity is good and an appropriate heat generation time can be obtained.

Example 4 Alumina cement 100 of alumina cement symbol c in Table 1
The procedure was performed in the same manner as in Example 1 except that the organic acid salt was blended with the parts by weight as shown in Table 5 and pulverized using a vibration mill. The results are also shown in Table 5.

<Materials Used> Organic acid salt A: sodium polyacrylate, manufactured by Nippon Pure Chemical Co., Ltd. Organic acid salt B: polysodium methacrylate, manufactured by Nippon Pure Chemical Co., Ltd. Organic acid salt C: sodium citrate, manufactured by Ishizu Pharmaceutical Co., Ltd. Primary reagent Organic acid salt D: A mixture of sodium polyacrylate / sodium citrate at a weight ratio of 1 / 0.6 Organic acid salt E: A mixture of polysodium methacrylate / sodium citrate at a weight ratio of 1 / 0.3 Organic acid salt F: Poly Sodium acrylate / polysodium methacrylate / sodium citrate weight ratio 0.5 / 1 /
0.4 mixture

[0040]

[Table 5]

Example 5 As shown in Table 6, the procedure was performed in the same manner as in Example 4 except that an inorganic salt was used instead of the organic acid salt. The results are also shown in Table 6.

<Materials> Inorganic salt a: Sodium carbonate, first-class reagent manufactured by Ishizu Pharmaceutical Co., Ltd. Inorganic salt b: Sodium hexametaphosphate, first-class reagent manufactured by Ishizu Pharmaceutical Co., Ltd. Inorganic salt c: sodium carbonate / sodium hexametaphosphate weight ratio 0.5 / 1.2 mixed Goods

[0043]

[Table 6]

Example 6 As shown in Table 7, an alumina cement composition was prepared by using 1.0 part by weight of an organic acid salt and 0.7 part by weight of an inorganic salt with respect to 100 parts by weight of an alumina cement having an alumina cement code c.
The same operation as in Example 4 was performed except that alumina cement was used instead. The results are also shown in Table 7.

[0045]

[Table 7]

Example 7 Using the irregular shaped refractory prepared in Example 1, 4 × 4 × 16
A test specimen of cm was molded and cured at 20 ° C., and the strength was measured. The results are also shown in Table 8.

[0047]

[Table 8]

Example 8 The same procedure as in Example 7 was carried out except that the alumina cement shown in Table 9 was used. The results are also shown in Table 9.

[0049]

[Table 9]

Example 9 The same procedure as in Example 7 was carried out except that the type and the amount of the refractory aggregate were changed as shown in Table 10 by using the alumina cement with the alumina cement symbol b in Table 1. Table 1 shows the results
0 is also added.

[0051]

[Table 10]

Example 10 Alumina cement 100 of alumina cement symbol c in Table 1
The procedure was performed in the same manner as in Example 7, except that the organic acid salt and the inorganic salt were blended with respect to the parts by weight as shown in Table 11, and pulverized using a vibration mill to prepare an alumina cement composition. . The results are shown in Table 11.

[0053]

[Table 11]

As is clear from the table, by combining two or more distributions, a broad particle size distribution is obtained, and the fluidity, the filling property, and the strength development are improved.

[0055]

When the alumina cement of the present invention is used, the workability and strength can be remarkably improved even in a construction atmosphere of 30 ° C. or more, as compared with the conventional cement. Further, the alumina cement of the present invention is excellent in heat resistance and early-hardening properties, and thus can be used as a steel material-related furnace material in combination with a refractory aggregate.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C04B 7/32 C04B 28/06

Claims (2)

(57) [Claims] 1. A peak of particle size distribution having a particle size range of 2 to less than 8 μm, a particle size range of less than 2 μm and / or a particle size range of 8 μm or more having CaO.Al ₂ O ₃ as a main component as a hydraulic component. 30% by weight of powder contained in one of the particle size ranges
An alumina cement characterized by the above. 2. An amorphous refractory comprising the alumina cement according to claim 1 and a refractory aggregate.