JP2003012378A - Castable refractory material and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refractory material excellent in durability, and improved in erosion resistance, by evading erosion, and deterioration caused by containing ingredient of the refractory material to be used in the melting furnace, and a manufacturing method of the refractory material. SOLUTION: The manufacturing method of the castable refractory material is that the castable refractory material containing 50-90 wt.% grain, the main ingredient of which is ZrB2 , <=45 wt.% solid solution grain comprised of Al2 O3 , and Cr2 O3 , and 5-50 wt.% ZrO2 grain, and the grain, the main ingredient of which is ZrB2 are mixed with 1-20 wt.% water and kneaded, cast into a mold, and dried at the room temperature - 30 deg.C. After released from the mold, dried for 10-30 hrs at the room temperature - 30 deg.C, thereafter dried for 10-30 hrs a the temperature of 100-500 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an amorphous refractory material preferably used in a melting furnace and a method for producing the same. More specifically, it is used for melting wastes and refuse incineration ash discarded from general facilities. The present invention relates to an amorphous refractory material which is preferably used as a material in a melting furnace. In particular, amorphous fire resistance for crucibles used in a system that melts and reduces the volume of solid waste (metals, filters, heat insulating materials, glass, concrete, refuse incineration ash, etc.) generated from general facilities by high frequency induction heating. Regarding materials

[0002]

2. Description of the Related Art Conventionally, waste has been packed in drums and then stored, but it also requires a vast site for storage. Therefore, there is a need for a technique for storing waste after melting it to reduce its volume. By melting the above wastes together in the furnace regardless of the type, the volume of the wastes can be reduced to about 1/6.

On the other hand, there are several types of refractory materials used in high frequency induction furnaces, and one of them is
There is a product obtained by adding an appropriate antioxidant to a main raw material such as graphite, silicon carbide, alumina, silicon metal or a silicon alloy, appropriately adding ceramics as a binder, kneading, molding and firing. As a crucible for a high frequency induction furnace, its electrical resistivity is an important characteristic, and it is necessary to have an electrical resistance above a certain level. The electrical resistivity value is adjusted by changing the type of binder used during production. As the binder used during production, clay or a ceramic binder is used.

When the solid waste as described above is melted in a high frequency induction furnace, the heat generated in the crucible is conducted to the waste and the conductive metal contained in the waste directly induces heat. Usually 1600 for melting these solid wastes
High temperatures around ℃ are required. Therefore, the crucible for this application is required to have a property as a heat generating container capable of withstanding the induction heat generation of 1600 ° C. or higher for a predetermined time or longer. However, the conventional crucible made of the refractory material as described above often deteriorates in such an environment, and there is a problem that the oxidative deterioration is severe in the oxidizing atmosphere and the service life is short, and the electric resistivity value is low. In many cases, it did not meet the specifications of the induction furnace.

On the other hand, another type of refractory material used in a high frequency induction furnace has been proposed in which a binder component is added to ZrB ₂ . Such conventional amorphous refractory materials use about 3 to 10% by weight of a binder such as cement for solidifying, in addition to the aggregate material and the matrix material. However, in the above material composition, even if an optimal aggregate component is used to improve the corrosion resistance of the irregular shaped refractory material, the binder component causes deterioration of the corrosion resistance, so there is a limit to the corrosion resistance of the irregular shaped refractory material. there were. From this, with respect to the durability of the refractory that constitutes the melting furnace, due to the erosion starting from the deterioration of the binder component cement,
The refractory life was shortened. As a result, it becomes difficult to operate the melting furnace stably for a long period of time, which causes problems such as frequent inspections of refractory materials and cost burdens during repair and replacement.

[0006]

SUMMARY OF THE INVENTION In view of the above problems, the present inventors have proposed a refractory material used inside a melting furnace as follows.
To develop a material that can improve the durability of refractories by avoiding deterioration due to cement components used as binders, improving corrosion resistance, and avoiding replacement / repair of refractory itself due to deterioration. Diligently studied. As a result, the present inventors have used ZrB ₂ having excellent corrosion resistance as a main component, without using any binder component such as cement,
It has been found that mixing the solid solution of alumina-chromia and ZrO ₂ solves the above problems. The present invention has been completed from this point of view, and an object thereof is to provide a refractory material for a crucible for a high-frequency induction furnace, which is suitable for a melting furnace and has a long service life at high temperatures.

[0007]

That is, the present invention is based on Z
50 to 90% by weight of particles containing rB ₂ as a main component, Al ₂ O
An amorphous refractory material comprising 45% by weight or less of solid solution particles composed of ₃ and Cr ₂ O ₃ and 5 to 50% by weight of ZrO ₂ particles. Further, in the present invention, particles containing ZrB ₂ as a main component are kneaded by adding 1 to 20% by weight of water, poured into a mold, dried at room temperature to 30 ° C., and then removed from the mold to further add 10 to 30%. About room temperature to 3 hours
After drying at 0 ℃, 10 ~ 10 at the temperature of 100 ~ 500 ℃.
The present invention provides a method for manufacturing an irregular shaped refractory material, which comprises drying for about 30 hours. When it is used as a strength member, in addition to the above steps, about 18
It is preferable to perform firing at 00 ° C. in an inert gas atmosphere or vacuum for 10 hours or less. With the refractory material of the present invention,
It is possible to avoid deterioration due to the cement component in the refractory material, reduce replacement and repair of the refractory material itself due to deterioration, and improve the durability of the refractory material installed inside the melting furnace.

The refractory material of the present invention has an amorphous shape like concrete, and the amorphous material is a material that is solidified after being filled in a container or a mold and then solidified. Conventionally, in the case of concrete, cement has been mixed as a binder for solidifying. Cement, which is a binder, has the optimum composition of components for hardening. Therefore, it has a drawback that it is easily deteriorated in a severe environment in a melting furnace and its corrosion resistance is poor. The reason why this corrosion resistance is poor is that when alumina (Al ₂ O ₃ ) cement used as a binder is subjected to the above-mentioned melting treatment, silica, calcia, magnesia, etc., contained in the heat insulating material (heat insulating material) that is a melt It was easy to react with the substance. As a result, the environment in which the refractory material is likely to deteriorate becomes higher, and the deterioration is further accelerated at high temperatures. Therefore,
There has been a long-felt demand for a refractory material that can be solidified without including such a binder component that easily deteriorates.

Further, even if the binder does not contain a regular refractory material, it can be manufactured by solidifying a powdery raw material and then sintering it in a firing furnace. However, in the case of an irregularly shaped refractory material, a binder component (cement or the like) is required if the material is poured into a mold and then solidified without being sintered. The refractory material of the present invention is a binderless refractory material that does not contain a binder component and is solidified only by intermolecular force, and does not require a content to act as a binder, thereby improving the corrosion resistance significantly. Is. Therefore, neither organic binder, refractory clay nor ceramic binder is used for the purpose of acting as a binder.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The amorphous refractory material of the present invention is ZrB.
50% to 90% by weight of particles containing ₂ as a main component, 0 to 45% by weight of solid solution particles composed of Al ₂ O ₃ and Cr ₂ O _3, preferably 0 to 20% by weight, and ZrO ₂ particles of 5% by weight.
.About.50% by weight, preferably 5 to 20% by weight. The compounding ratio of ZrB ₂ is adjusted so as to have an electric resistivity value according to the high frequency induction furnace to be used, but 50 to 90
It must be in the range of weight%. If it is less than 50% by weight, the corrosion resistance as a refractory material such as a crucible lowers and the crucible life shortens. On the other hand, if it exceeds 90% by weight, the electric resistivity value becomes too low and the crucible heat is generated during high frequency induction heating, which makes it difficult to dissolve the conductive waste.

For ZrB ₂ , particles having different sizes are usually mixed to form a close-packed refractory material. If an example of the optimal combination for finely packing without forming a gap is shown, (i) 3 to 5 mm, (ii) 1 to 3 mm, (iii) 0.1 to 1
mm, (iv) used is a mixture of four types of particles having different particle sizes of less than 0.1 mm. As the mixing ratio, for example,
(i) particles 20 to 30%, (ii) particles 20 to 30%, (iii) particles 20 to 30%, (iv) particles 20 to 30% (total 100%)
A mixed component consisting of is preferred. Particles containing a large amount of impurities are not preferable because they may be decomposed and deteriorated during induction heating, resulting in changes in electrical characteristics and cracking of the crucible.

This ZrB ₂ is excellent in corrosion resistance against dissolved waste components, but on the other hand, it is as conductive as metal. In the waste melting furnace, it is necessary that the crucible has an electric resistance above a certain level because of high frequency induction heating. This is because when the crucible has high conductivity and conducts electricity, the waste is not heated and the crucible itself is heated. Specifically, it is desirable to adjust the electrical resistivity within the range of usually> 10 ^-2 Ωcm. The amorphous refractory used for the crucible has no conductivity,
It is necessary to use a material with good corrosion resistance, and ZrB
_In order to properly perform the melting process using ₂ , it is necessary to mix the following components to adjust the conductivity of the material.

In the refractory material of the present invention, Al ₂ O ₃ and Cr ₂ O _{3 are used.}
0 to 45% by weight of solid solution particles consisting of
˜20% by weight. If the blending ratio is too large, the corrosion resistance is severely deteriorated, which is not preferable, and the blending ratio needs to be 45% by weight or less. The solid solution composed of Al ₂ O ₃ and Cr ₂ O ₃ has improved corrosion resistance as compared with the case where cement is used by mixing instead of cement from the viewpoint of binderless. The composition ratio of the solid solution is Al ₂ O ₃ / Cr ₂ O ₃
Is usually 10 to 30/90 to 70, for example, 20/8
20Al ₂ O ₃ -80Cr ₂ O ₃ consisting of the ratio of 0 is preferably used. The particle size of the solid solution is not particularly limited, but a mixture of solid solutions having particle sizes of 1 to 3 mm and less than 1 mm and having two or more particle sizes is preferable.

The above solid solution is generally produced by dissolving alumina and chromia in an electric furnace at the same ratio to form a solid solution. Although corrosion resistance deteriorates only with alumina, the solid solution prevents the adverse effect of alumina. Alumina has a deteriorating effect on non-metals such as slag, while chromia, on the other hand, is a material that easily deteriorates on dissolved metals. In the present invention, by using a solid solution obtained by solidifying both of these components, the properties that tend to deteriorate alone complement each other,
The waste becomes a strong material that does not easily deteriorate with respect to all the melted components.

The refractory material of the present invention further contains 5 to 50% by weight of ZrO ₂ particles. It is preferable to use medium to fine zirconia particles with a medium particle size of 100 μm.
It is preferable to use one having a particle size of up to 1000 μm in combination with a fine particle portion having a particle size of 100 μm or less in view of the filling property and the particle size configuration based on the crucible shape.

In the melting furnace using the refractory material of the present invention, the wastes to be melted include all wastes discarded in general facilities. For example, it includes clothes or clothing worn by workers who are working, consumables or replacement parts in the plant, concrete or reinforced concrete grounded in the plant. Further, as one of the large amounts of waste, when the facility has a high-temperature power generation plant or the like, a cotton-like ceramic material such as a heat insulating material or a heat insulating material used between them is cited. Therefore, the waste materials put into the melting furnace include various materials such as metal and plastic.

Next, a method for manufacturing the irregular refractory material of the present invention will be described. In the production method of the present invention, 1 to 20% by weight of water is added to particles containing ZrB ₂ as a main component, kneaded, poured into a mold, dried at 0 to 30 ° C., and then removed from the mold for further 10 After being dried at room temperature to 30 ° C for about 30 hours, it is dried at 100 to 500 ° C for about 10 to 30 hours. When a refractory material is used as a strength member, it is further added and fired at about 1600 to 2000 ° C., for example, 1800 ° C. in an inert gas atmosphere or in vacuum within 10 hours.

In the conventional embodiment in which the cement component is contained as the binder, the material is solidified in the mold and then fired. However, in the case of solidifying in a mold, since there is only a direction in which moisture evaporates only during solidification, a refractory material with many gaps in a certain direction was formed. In the present invention, it is possible to maintain a certain degree of shape, remove from the mold at a stage before solidification, and dry at room temperature,
Hold it as a constant shape. After that, the temperature is 100 ℃
A two-step drying process of raising the temperature to the above and drying is performed.
Further, if necessary, it is baked at a high temperature.

Here, the irregular-shaped refractory material contains water like concrete, but the shape of the refractory material shrinks and contracts as much as water evaporates. It is preferable to reduce the amount of water, and in the present invention, 20% by weight of water at the maximum is added for kneading. In conventional refractories containing cement, water was required for hydrolysis of cement, but in the present invention, water for reacting cement is not required. On the other hand, if the amount of water is less than 1% by weight, it is not preferable because the fluidity of particles during production is lowered. Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to these Examples.

[0020]

EXAMPLES Example 1 In the production of refractory material, first, 4-14 # (5-1 mm), 1
ZrB ₂ particles having a particle size of 4 to 150 # (1 to 0.1 mm) were mixed at the compounding ratio shown in Table 1. In addition, solid solution particles of Al ₂ O ₃ and Cr ₂ O _{3 having} a ratio of 20/80, 20 Al ₂ O ₃ -80Cr ₂ O ₃ particles, 1 to 3 mm, 10
Those having each particle size of 0 # or less were mixed, and zirconia (ZrO ₂ ) was also mixed in the compounding ratio shown in Table 1.

20% by weight of water was added to the blended raw materials, kneaded, and then poured into a mold. Mold at room temperature, 1
It was dried for about 0 to 30 hours. Then, after removing from the mold and further drying for about 20 hours, it was dried at a temperature of 400 ° C. for 24 hours. In this example, the refractory material was further fired at 1800 ° C. in an inert gas atmosphere for 3 hours. For the obtained refractories (1 to 3), the following erosion test was conducted in a melting furnace in order to investigate the corrosion resistance. The results are also shown in Table 1. Erosion test:
High frequency induction furnace, 1600 ° C for 3 hours

[0022]

[Table 1] Note) In the table, in the erosion test results, ⊚ indicates that there is little erosion and it is extremely good.

The embodiments and examples have been described above for facilitating the understanding of the present invention. However, the present invention is not limited to the above-described embodiments and examples, and the gist of the present invention Various modifications and changes can be made without departing from the above.

[0024]

According to the crucible for high frequency induction furnace using the refractory material of the present invention, the solid waste can be heated and melted at a high temperature of about 1600 ° C. by the high frequency induction heating system, and further, such Even if you keep the high temperature heating state for a long time,
The crucible is resistant to erosion and deterioration and has excellent durability. Therefore, it becomes possible to carry out the melting process in the melting furnace continuously and stably for a long period of time.

Continued front page    (72) Inventor Ichigo Mori             2-1-1 Niihama, Arai-cho, Takasago, Hyogo Prefecture             Takasago Laboratory, Mitsubishi Heavy Industries, Ltd. (72) Inventor Takehiko Hirata             1-8 Koura, Kanazawa-ku, Yokohama-shi, Kanagawa               Mitsubishi Heavy Industries, Ltd. Basic Technology Research Center (72) Inventor Tetsuhiko Kodama             1-1 1-1 Wadasaki-cho, Hyogo-ku, Kobe-shi, Hyogo             No. Mitsubishi Heavy Industries, Ltd.Kobe Shipyard F-term (reference) 4G001 BA01 BA03 BA45 BB01 BB03                       BB45 BD07                 4G033 AA00 AA02 AA07 AA08                 4K051 AA00 AB03 AB05 BE03

Claims (3)

[Claims] 1. Particles containing ZrB ₂ as a main component in an amount of 50 to 9 are used.
0% by weight of solid solution particles consisting of Al ₂ O ₃ and Cr ₂ O ₃
5% by weight or less, and 5 to 50% by weight of ZrO ₂ particles
Amorphous fireproof material characterized by containing. _2. Particles containing ZrB ₂ as a main component, 1 to 2
After adding 0% by weight of water to the mixture and kneading it, the mixture was poured into a mold, dried at room temperature to 30 ° C, removed from the mold and further dried at room temperature to 30 ° C for about 10 to 30 hours, and then at a temperature of 100 to 500 ° C. A method for producing an irregular shaped refractory material, which comprises drying for about 10 to 30 hours. 3. The method for producing an irregular refractory material according to claim 2, further comprising firing at 1600 to 2000 ° C. in an inert gas atmosphere or in vacuum for 10 hours or less.