JPH11291213A - Method for forming castable refractory block - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a castable refractory block which has a uniform pore distribution and is suitable for the constitution of a highly durable mass block, a plug for gas blasting, and others. SOLUTION: A method for forming a castable refractory block has a process in which a kneaded castable refractory 3 is cast into a porous molding mold 2 in which an average pore diameter on side of the inner wall surface is 1-30 μm and a process in which the pores of the mold 2 are evacuated and vibrated so that the cast refractory 3 is packed enough to be a block. The porous mold 2 is preferably made of a synthetic resin or a ceramic.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming an irregular-shaped refractory block, and more particularly to a method for forming a dense, highly durable irregular-shaped refractory block having less variation in pore distribution.

[0002]

2. Description of the Related Art Mass blocks used in molten steel ladle and tundish, and large block products such as gas blow plugs are difficult to manufacture by press molding. Casting, curing,
It is formed into a block by removing the frame and drying. In other words, prepare a wooden or metal mold,
After the mold surface of this mold is treated with a mold release agent such as machine oil, an irregular refractory prepared by kneading with added water is injected (poured or charged) to form and solidify. In addition,
Generally, the amorphous refractory is gradually poured or charged while defoaming by placing a mold on a shaking table or using a rod-shaped vibrator.

[0003] However, in the case of the above-mentioned method for forming an irregular-shaped refractory block, the diameter of the compact, which is regarded as an aggregate of small bubbles, is considered.
Large bubbles of about 5 mm tend to remain. Especially,
In the latter half of the casting of the amorphous refractory, the upper part of the molded body is more likely to remain bubbles by shortening the vibration time as compared with the lower side bubble rising and lower side, and the densification is impaired, The overall pore distribution becomes non-uniform (variable).

That is, it is difficult to obtain an irregular-shaped refractory block having sufficient spall resistance and hot metal resistance required as a refractory material. In order to reduce the pores and make the pore distribution uniform, it is effective to extend the vibration time or to reduce the amount of the amorphous refractory that can be poured at one time as much as possible. Phenomena such as settling and breathing cause variations in quality.

[0005] In order to densify the molding block, there has been proposed a method in which an amorphous refractory is kneaded under reduced pressure or cast into a molding die by vibration under reduced pressure (JP-A-8-1697).
No. 54). That is, means has been developed in which water is added to an amorphous refractory material, kneaded, and then pressure-reduced vibration casting is performed in a molding die to cure, deframe, and dry.

[0006]

In the case of casting by the above-described kneading under reduced pressure or vibration under reduced pressure, an improvement in defoaming ability can be expected. However, kneading under reduced pressure causes a slight decrease in water content and also removes bubbles having a diameter of 1 mm or less which contribute to fluidity, so that fluidity at the time of pouring into a mold is impaired,
In addition, there is a problem that bubbles are easily generated when pouring into a molding die.

On the other hand, in the case of reduced pressure vibration, it is necessary to house the entire mold in a vacuum container, and the equipment becomes large. Moreover, since the addition of water and the defoaming of the kneaded material of the amorphous refractory material poured (injected) into the mold are performed only from the upper surface side which is not in close contact with the mold, the height of the pouring amount (depth or As the thickness increases, the defoaming effect decreases. Here, if the degree of vacuum (decompression degree) is increased in order to obtain a sufficient defoaming effect to the lower side of the construction body, freezing of moisture may occur or the construction body surface may become extremely uneven. There is.

As a means for forming the metal powder, a slurry prepared by adding a dispersion medium to the metal powder, a curable resin (for example, an epoxy resin) for forming an emulsion with the dispersion medium, and a curing agent for the curable resin. It is known that a liquid is poured into a mold having a dewatering ability, and is dewatered and hardened (Japanese Patent Laid-Open No.
No. 5-195019). However, in the case of this molding method, since the curable resin functioning as a binder and its curing agent are likely to shrink or volatilize during drying and firing and to generate cracks, etc., in general, an amorphous refractory resin is used. Cannot be diverted to floc formation.

Accordingly, the present invention provides a method for forming an irregular-shaped refractory block which has a sufficient density for practical use, has no variation in pore distribution, and is suitable for the construction of a highly durable mass block or a gas blowing plug. The purpose is to do.

[0010]

The invention according to claim 1 comprises a step of pouring an amorphous refractory kneaded into a multi-hard mold having an average pore diameter of 1 to 30 μm on the inner wall side, and Depressurizing the pores and applying vibration to form a refractory block into a filled block, thereby forming a refractory block.

According to a second aspect of the present invention, in the method for forming an irregular shaped refractory block according to the first aspect, the multi-hard mold is made of a synthetic resin.

According to a third aspect of the present invention, in the method for forming an irregularly shaped refractory block according to the first aspect, the multi-hard mold is made of ceramics.

That is, the present invention uses a multi-hard mold having an average pore diameter of 1 to 30 μm on the inner wall side.
Depressurizing and sucking the irregular-shaped refractory poured into this mold through the multi-hard body of the mold, and applying further vibration to the irregular-shaped refractory poured into the mold to achieve filling and densification. Is the main point.

FIG. 1 is a sectional view schematically showing the outline of an embodiment of the present invention. For example, a mold made of a multi-hard body having an average pore diameter of 1 to 30 μm on the inner wall surface is provided on the upper surface of a vibrating table 1. 2 is placed (attached / set), and a raw material (raw material) 3 for forming an amorphous refractory block is poured (injected) into the molding die 2 made of a multi-hard body.

Here, examples of the material of the multi-hard body constituting the molding die 2 include synthetic resins (resins), ceramics, refractories, gypsum and the like. Resins (resins) and ceramics are preferred. Also, the inner wall surface side of the multi-hard mold 2 is selected and set to have an average pore diameter of 1 to 30 μm because the average pore diameter is 1 μm.
If it is less than μm, the irregular refractory 3 poured into the mold 1
The depressurization and defoaming effect on the surface is small, and as a result, a dense amorphous refractory block cannot be formed. On the other hand, the average pore diameter is
When the thickness exceeds 30 μm, a sufficient depressurizing and defoaming effect is exerted on the amorphous refractory 3 poured into the mold 1, but clogging of pieces and pores is likely to occur, and as a result, Unable to form irregular refractory blocks.

On the other hand, the raw material (raw material) 3 used for forming the amorphous refractory block includes, for example, high alumina, alumina-spinel, alumina-magnesia, and the like used for forming a mass block, a gas blowing plug, and the like. Alumina-carbon and the like can be mentioned. As for the raw material (amorphous refractory) 3 to be used, a compact having a low moisture content can be formed and the strength can be expected to be improved. Therefore, to improve the corrosion resistance, the alumina cement in the amorphous refractory 3 is used. It is desirable to reduce the amount. The amount of the irregular-shaped refractory 3 to be poured into the multi-hard mold 2 is determined by the irregular-shaped refractory 3.
Although it differs depending on the viscosity of the mold and the shape of the molding die, it is preferable that the casting amount is about 300 mm or less per operation.

Further, since it is premised that the multi-hard mold 2 has a function of reducing the pressure of the cast refractory 3, it is necessary to maintain a function other than the inner wall surface with which the cast refractory 3 comes into contact. Preferably, the surface is coated with a water-resistant film 4, for example.

The pressure of the cast refractory 3 is reduced by, for example, a vacuum pump (not shown). The multi-hard mold 2 is set in the pressure-reducing system region, or the multi-hard mold is formed. A mode in which the outer wall surface of the mold 2 is appropriately connected to a decompression system is adopted. And the shaking table 1
By applying vibration to the molding die 2 by the driving of and the depressurization of the molding die 2, defoaming and excess moisture are efficiently removed, and dense filling proceeds.

That is, some of the bubbles in the amorphous refractory 3 poured into the mold 2 rise and are removed from the opening of the mold 2, while the vibration and pressure reduction of the mold 2 are coordinated. By the action, the mobility of bubbles and excess moisture in the cast refractory 3 is improved and promoted. Therefore, air bubbles and excessive moisture are easily removed, and a dense, uniform-shaped refractory block (uniform refractory block) having a uniform pore distribution is formed. It should be noted that the application of vibration to the molding die 2, in other words, the application of vibration to the amorphous refractory 3 poured into the molding die 2, can also be performed by, for example, a rod-shaped vibrator.

After the formation of the irregular-shaped refractory block (constructed body) in the molding procedure, the removal of the irregular-shaped refractory block formed from the mold 2 is not particularly limited, but is preferably performed as follows. That is, when a small amount of water is added into the mold 2 and the irregular refractory block in the mold 2 is pressed from the outside by, for example, a compressor or the like, even if the mold release agent treatment on the inner wall surface of the mold 2 is omitted. The irregular shaped refractory block can be easily removed. In the drying after removal from the mold, the formed refractory block is dense and easily generates cracks.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Nine types of molds capable of forming a molded body having a sample size of 40 × 40 × 160 mm were prepared. That is,
Resin mold with average pore size of 3 μm (mold A), resin mold with average pore size of 7 μm (mold B), average pore size of 20 μm
m resin mold (mold C), resin mold with average pores of 0.5 μm (mold a), resin mold with average pores of 35 μm (mold b), gypsum mold with average pores of 7 μm (mold A mold D), a gypsum mold (mold E) having an average pore size of 3 μm, and an iron mold (mold c) were prepared. In addition, a porous mold (A, B, C, D, E, a, b)
Among them, in addition to the mold E used in Example 8, a water-resistant coating treatment was performed in advance.

On the other hand, to a high-alumina, alumina-spinel, or alumina-magnesia amorphous refractory having a composition (% by weight) shown in Tables 1 and 2, 2% by weight of externally added clean water was added. Kneading with a 5000ml tabletop mixer
Prepare. Subsequent to this preparation, each mold was poured (injected) into the prepared mold, and the mold was evacuated from the outer wall surface side by a vacuum pump, while being subjected to vibration molding on a vibrating table. . In the case of molding using an iron mold (mold c) (comparative example), depressurization of the mold was omitted, and kneading / preparation of the refractory of irregular shape and the mode of vibration were changed. I have. Tables 1 and 2 also show these molding conditions and the number of times each mold can be used repeatedly.

After filling each of the kneaded and prepared irregular-shaped refractories in a mold, leave and cure at room temperature for 24 hours, when a porous mold is used, a small amount of water is used. While being added into the mold, the mold was demolded while applying compressor pressure from the outer peripheral surface side of the mold. The demolded filled molded body was dried at 110 ° C. for 24 hours, and further dried for 15 minutes.
At each point of time when sintering was performed at 00 ° C. for 24 hours, their bulk specific gravity,
The results of measuring and evaluating the apparent porosity (%) and the bending strength (MPa) are shown in Tables 1 and 2.

The results of the erosion / infiltration test (measurement of erosion / infiltration from the cut surface of the sample) for the molded body (40 × 40 × 160 mm) dried at 110 ° C. × 24 hours are shown in Table 1. And Table 2 together. The erosion and infiltration test was performed by an induction furnace dipping method using an erosion agent of synthetic slag (C / S = 2) and a test temperature of 1650 ° C. Here, the erosion index and the infiltration index are relative values to the values obtained by setting the erosion index and the infiltration index of Example 1 to 100, respectively, and the smaller the value, the better the erosion resistance and the infiltration resistance.

[Table 1]

[Table 2] As can be seen from the above-described tests and evaluations, in the case of the amorphous refractory block according to the example, the variation in the pore diameter is smaller and the porosity is significantly larger than the amorphous refractory block of the comparative example. Reduced, exhibiting excellent mechanical strength and corrosion resistance. For example, using a resin molding die (molding die F) having an average pore size of 7 μm and applying pressure reduction and vibration in accordance with the above-described embodiment, the actual shape of the porous plug outer ring (material: alumina, diameter: 80 / diameter) 200 × 300m
m) was filled (Example 8). Also, for comparison,
Using the iron mold (mold c), pressure reduction and vibration were applied in accordance with the comparative example, and a porous plug outer ring (material: alumina, diameter 80 / diameter 200 ×
(Comparative Example 7).

After drying both of the above compacts at 110 ° C. for 24 hours, the dried compacts were divided into four sections: an upper part, an upper central part, a lower central part, and a lower part. It is shown in Table 3. In addition, in the case of this example, as compared with the comparative example, not only the large-diameter pore of about 5 mm did not exist, but also the porosity was reduced and the porosity variation was reduced.

[0026]

[Table 3] Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention. For example, the shape and dimensions of the mold, the composition and material of the refractory, and the like can be selected according to the application.

[0027]

According to the present invention, in various industrial kilns, fire-resistant structural members having excellent durability can be easily provided with a high yield. That is, according to the method for forming an irregular-shaped refractory block according to the present invention, for example, suitable for the configuration of a molten steel ladle such as a mass block or a porous plug outer ring, or a tundish.
It is possible to provide an amorphous refractory block which is dense and has a small variation in pore distribution, is excellent in erosion resistance / infiltration property, mechanical strength, and the like, in a mass-production manner and with a high yield.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing a basic embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Shaking table 2 ... Porous molding die 3 ... Material for forming an amorphous refractory block 4 ... Water resistant film

Claims (3)

[Claims] 1. A step of pouring a kneaded amorphous refractory into a multi-hard mold having an average pore diameter of 1 to 30 μm, and reducing the pressure of the pores of the multi-hard mold and applying a vibration to the irregular mold. Filling the refractory with a refractory and blocking the refractory. 2. The method according to claim 1, wherein the multi-hard mold is made of a synthetic resin. 3. The method according to claim 1, wherein the multi-hard mold is made of ceramics.