JP2002308677A - Binder for graphite-containing monolithic refractory and graphite-containing monolithic refractory using the binder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a binder for graphite-containing monolithic refractories which has no reduction of strength in all temperature regions from ordinary temperatures to hot temperatures, and can hot-form a bond with graphite, and graphite-containing monolithic refractories using the binder. SOLUTION: (1) The binder for graphite-containing monolithic refractories contains resin, pitch and metal (Si and/or Al) powder as the main components, and in which the mass ratio of the total content of the pitch and resin to the total content of the pitch, resin and metal powder is 0.6 to 0.9. (2) The graphite- containing monolithic refractories are obtained by mixing the binder for graphite-containing monolithic refractories of the (1) into a refractory material containing a refractory filler and graphite powder as the main components. The total solid content in the refractories contains <=1.5 mass% alumina cement and 0.1 to 1 mass% resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a graphite-containing refractory binder used in the steel industry and a graphite-containing refractory using the same.

[0002]

_2. Description of the Related Art In recent years, refractories containing graphite, such as refractory for continuous casting of Al ₂ O ₃ -C, including MgO-C bricks of converters, are generally used in the steelmaking industry. It is becoming. This flow is the same for irregular refractories, such as Al ₂ O ₃ -SiC-C pouring materials for blast furnace main gutters and MgO- for ladle slag lines.
A typical example is a C material. With these graphite-containing cast materials, if the corrosion resistance inherent in graphite is sufficiently exhibited, slag penetration does not occur and the sponging resistance is sufficient, so that excellent durability is expected. .

[0003] However, the penetration rate of the cast material containing graphite is not always high. The cause is simply that the graphite-containing casting material is worn away without taking advantage of the high corrosion resistance of graphite. The reason is that alumina cement, which has been used as a binder for the conventional graphite-containing pouring material, cannot bond graphite to each other or graphite and Al ₂ O ₃ , refractory particles such as MgO during heating. As a result, slag,
It is said that graphite is shed in a portion where there is a flow of hot metal or the like.

In order to bind graphite, for example, as disclosed in JP-A-6-287707, a method of kneading with a phenol resin solution instead of water and using a phenol resin as a binder is disclosed. Is disclosed. However,
According to this method, the graphite is easily wetted by the phenol resin solution, but the refractory ultrafine powder (the Al ₂ O ₃ , MgO
Refractory particles, etc.) are not easily wetted by the same liquid, so that a large amount of phenol resin must be added to facilitate kneading. As a result, pores in the refractory after drying and preheating are obtained. However, there is a problem that a dense refractory structure cannot be obtained due to an increased rate. In addition, the phenol resin undergoes polymerization at around 200 ° C. to obtain high refractory strength, but at 600 ° C. or higher, carbonization proceeds and causes a decrease in refractory strength. The greater the amount, the more significant.

[0005] On the other hand, a technique of adding pitch or metal powder to improve the hot strength of refractories has also been disclosed. For example, according to Japanese Patent Publication No. Sho 60-41027, by adding metallic silicon powder so that the Si content of the carbon-containing refractory aggregate becomes 0.5 to 5% by weight, the Si-C bond is generated during heating during use. It is said to produce a bond. Japanese Patent Publication No. 58-49511 also discloses that it is effective to add resin-coated aluminum so that the Al content of the amorphous refractory is 0.1 to 5% by weight. However, such a metal does not develop its own strength, but develops its strength only by bonding with carbon. Therefore, the amount of such a metal to be added is set to an appropriate value according to the amount of carbon that is a carbide-forming partner. Should be determined, and its optimization has not yet been made.

[0006]

As described above, the conventional graphite-containing amorphous refractory binder has a problem that it is difficult to maintain the hot strength of the graphite-containing amorphous refractory after application at a sufficiently high level. there were. The present invention solves this problem, a graphite-containing amorphous refractory binder capable of forming a bond that binds graphite hot without causing a reduction in strength in the entire temperature range from room temperature to hot, and a use thereof. It is an object of the present invention to provide a graphite-containing amorphous refractory.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, when the alumina cement content of the amorphous refractory is brought to near 0% as much as possible, the temperature of around 800 ° C. The decrease in strength due to the collapse of alumina cement is reduced, and the amount of liquid phase generated at high temperatures is reduced.When resin is added to the binder, the ordinary temperature strength of the amorphous refractory is improved by the curing reaction. The inventors have obtained an important finding that the addition of pitch and metal at a specific ratio improves the high-temperature strength of the amorphous refractory, and have accomplished the present invention.

That is, the present invention provides a resin, a pitch, and a metal powder as main components, further contains a room-temperature curing agent, the balance is composed of unavoidable impurities, and the pitch relative to the total content of the pitch, the resin, and the metal powder. And a graphite-containing binder for amorphous refractories, wherein the mass ratio of the total resin content is 0.6 to 0.9. Here, the metal powder is preferably a metal Si powder and / or a metal Al powder.

[0009] The present invention also relates to an amorphous refractory obtained by mixing the above-mentioned graphite-containing binder for an amorphous refractory with a refractory material mainly composed of a refractory aggregate and graphite powder. Refractory solid content is less than 1.5 mass% alumina cement,
Resin: A graphite-containing amorphous refractory containing 0.1 to 1% by mass. Here, the total solid content of the refractory is a refractory aggregate, a refractory material mainly composed of graphite powder, a fixed carbon content of the pitch, a fixed carbon content of the resin,
It means the sum of metal powder and room temperature curing agent.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The graphite-containing binder for amorphous refractories of the present invention (hereinafter referred to as the binder of the present invention) contains resin, pitch and metal powder as main components. Here, the main component means a component or a component group that is individually contained in an amount of 3% by mass or more, and a total of 95% by mass or more. Further, the binder of the present invention contains a room-temperature curing agent such that the content thereof in the graphite-containing amorphous refractory of the present invention described later is preferably 0.1 to 2% by mass. Room temperature curing agent is alumina cement,
It is composed of one or more of basic aluminum lactate, hydraulic alumina, condensed sodium phosphate, silica sol, and alumina sol. However, since alumina cement lowers the hot strength of the graphite-containing amorphous refractory after construction, the content of the binder of the present invention is desirably as small as possible. Specifically, the alumina cement content of the binder of the present invention is limited so that the graphite-containing amorphous refractory after application has an alumina cement content of 1.5% by mass or less.

The binder of the present invention is mixed with the refractory material to form a component of the graphite-containing amorphous refractory of the present invention (hereinafter referred to as the refractory of the present invention). In the graphite-containing amorphous refractory of the present invention, a preferable value of the binder content of the present invention is 5 to 5 as described later.
10% by mass. Therefore, in order to reduce the alumina cement content of the graphite-containing amorphous refractory after construction to 1.5% by mass or less, the alumina cement content of the binder of the present invention is at most a maximum.
The content is preferably 30% by mass or less.

If the alumina cement content of the binder is limited to a small amount for the above reasons, the back surface strength becomes insufficient when using graphite-containing amorphous refractories, and the walls of the inclined gutter, ladle, slag line, etc. There is a possibility that the construction body cannot be held. Therefore, the binder of the present invention contains a resin as an essential component. The resin content of the binder of the present invention is determined so that the resin content of the graphite-containing amorphous refractory after application falls within the range of 0.1 to 1% by mass. In the refractory of the present invention, the preferred value of the binder content of the present invention is 5 to 10 as described below.
% By mass. Therefore, in order to make the resin content of the graphite-containing amorphous refractory after the application to be 0.1 to 1% by mass, the resin content of the binder of the present invention is preferably 1 to 20% by mass. This resin may be in any state of liquid or powder, and may be in any form of resole or novolak.

When the resin is heated to a temperature of 600 ° C. or more, the resin carbonizes and causes a decrease in strength. It is pitch that reinforces this reduction in strength. The pitch carbonizes at 600 ° C or higher and contributes to strength development. At a higher temperature of 800 ° C. or higher, the reaction between the pitch and the metals Al and Si to form carbides becomes active. This carbide contributes to the development of hot strength. For this reason, resin, pitch, metal powder (one or two of Al and Si)
(Species mixture), a high-strength material can be obtained in all temperature ranges. That is, the effect of the present invention cannot be obtained only by adding the pitch or only by adding the metal powder, because the effect of improving the hot strength is small.

[0014] The carbide formation reaction by the pitch and the metal is specifically a reaction between the volatile matter of the pitch and the metal. Therefore, in order to obtain high strength, it is desirable to add a pitch having a high volatile content. A pitch having a high volatile content generally has a low melting point, but in the present invention, it is preferable to use a pitch which is solid at normal temperature and has a volatile content of about 20 to 40%. Preferably, the ratio of pitch to metal is in a range appropriate for producing Al ₄ C ₃ or SiC. Specifically, the mass ratio of (pitch + resin) / (pitch + resin + metal) in the binder is desirably 0.6 to 0.9. When the mass ratio is less than 0.6, C is insufficient, and when the mass ratio is more than 0.9, metal is insufficient, so that strength development hardly occurs.

The binder of the present invention is used by being mixed with a refractory aggregate and a refractory material mainly composed of graphite powder. In a mixture of the binder of the present invention and a refractory material (refractory of the present invention),
After the formation of an amorphous refractory using this as a material, the strength is exhibited by forming a bond between the graphites constituting the refractory material, or the graphite and the refractory aggregate particles, so that the refractory material is made of magnesia. , Alumina, zirconia, lime, dolomite, chamotte, spinel, SiC
Refractory aggregate (particle size 30μm or more) consisting of one or more commonly known refractory aggregates, and one of earth graphite, artificial graphite, scaly graphite, anthracite, and coke Alternatively, it must contain, as a main component, two or more kinds of graphite powder (particle diameter: 1 mm or less).

The refractory material may be composed of an unavoidable impurity except for the main component. However, in addition to the main component, SiO ₂ or Al ₂ O which is effective for improving the fluidity may be used.
Etc. ₃ fine powder (particle size 30μm or less) and carbon black, and / or useful SiC as antioxidants, B ₄
C, and other general refractory raw materials can be contained as long as the effects of the present invention are not impaired. The graphite raw material to be used can be subjected to a surface treatment that enhances dispersibility in water and fillability during construction.

The mass ratio (= content of the binder of the present invention) of the binder of the present invention to the entire refractory of the present invention obtained by mixing the refractory material and the binder of the present invention should be 5 to 10% by mass. Good. When the amount is less than 5% by mass, the effect of the binder of the present invention is dilute. When the amount is more than 10% by mass, the effect is saturated, and the ratio of the refractory material is relatively small, so that the performance of the obtained refractory deteriorates. This is because there is a possibility of doing so.

However, in the refractory of the present invention, more important than the binder content of the present invention are the alumina cement content and the resin content. That is, in the refractory of the present invention, when the alumina cement content is more than 1.5% by mass, the hot strength of the refractory construction using the refractory of the present invention as a material is reduced. Further, in the refractory material of the present invention, when the resin content is less than 0.1% by mass, the effect of developing the strength of the refractory construction body is small, while when the resin content is more than 1% by mass, the refractory construction body has a temperature of 600 ° C. or more. When exposed to temperature, its strength decreases significantly.

Therefore, in order to mix the binder of the present invention with the refractory material to make the refractory of the present invention, the total solid content of the obtained mixture is not more than 1.5% by mass of alumina cement,
It is necessary to determine the mixing ratio of the binder of the present invention and the refractory material so that the composition satisfies 0.1 to 1% by mass.

[0020]

EXAMPLE A mixture of a refractory material and a binder having various compositions shown in Table 1 was mixed with Al ₂ O ₃ -MgO −
Applied to C type cast refractory for casting.

[0021]

[Table 1]

In Table 1, Examples 1 to 5 show binders,
Both mixtures are within the scope of the present invention. In Comparative Example 1, the binder contained no resin, pitch, or metal powder, and the alumina cement content of the mixture was outside the scope of the present invention. In Comparative Example 2, the binder contained no resin, and the resin content of the mixture (total solid content) was outside the scope of the present invention described in claim 3. Comparative Example 3
Is a binder having a resin content within the scope of the present invention described in claims 1 and 2, but having a resin content of the mixture (total solid content) outside the scope of the present invention described in claim 3. is there. In Comparative Example 4, the binder does not contain pitch, and the (pitch + resin) / (pitch + resin + metal) of the binder falls outside the scope of the present invention. In Comparative Example 5, the binder contained no metal powder, and the (pitch + resin) / (pitch + resin + metal) of the binder was outside the scope of the present invention described in claim 1.

Using these mixtures as materials, irregular-shaped refractory construction was performed, and the performance of the obtained refractory construction was investigated.
The performance investigation items and test methods were as follows.・ 110 ° C dry body strength: Water is added and kneaded so that the flow value after tapping 15 times in the flow test becomes 140, and kneaded, 40 × 40 × 160m
m shape. After curing for 24 hours after molding, unframed, 11
The specimen dried at 0 ° C. for 24 hours was subjected to a three-point bending test using a Michaelis-type bending tester.

800 ° C. hot bending strength: A dried sample of 30 × 30 × 140 mm was prepared as described above, and heat-treated at 800 ° C. for 3 hours in a coke breathe.
A three-point bending test was performed in an electric furnace kept in an N ₂ atmosphere at ℃.・ 1400 ° C hot bending strength: Similarly, 1400 of 30 × 30 × 140mm
For ° C. reduction firing sample, 1400 ° C., it was carried out three-point bending in an N ₂ atmosphere test.

Table 1 shows the results of the performance investigation. From Table 1, in Examples 1 to 5, the dry strength at 110 ° C was 0.9 M in all cases.
More than Pa, 800 ° C Hot bending temperature more than 1.9 MPa, 1400 ° C
The hot bending strength was 1.2 MPa or more, and a bonded body with no reduction in strength was obtained over the entire temperature range where the actual furnace was used. On the other hand, in Comparative Example 1, strength was not obtained at 800 ° C. or higher, and in Comparative Example 2, 110 ° C. dry strength and 1400 ° C. hot strength were not obtained.
In Comparative Examples 3 to 5, hot strength at 1400 ° C. was not obtained.

[0026]

As described above, according to the present invention, it is possible to prevent the strength of the graphite-containing amorphous refractory from lowering from room temperature to hot after the refractory is applied, and the graphite-containing amorphous refractory inherently has a high height. It has an excellent effect of being able to exhibit corrosion resistance.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Etsuo Udagawa 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Prefecture Inside the Technical Research Institute of Kawasaki Steel Corporation (72) Inventor Masato Takagi 1-1-1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Inside the Technical Research Institute, Steel Works Ltd. 1576-2 Kawasaki Furnace Materials Co., Ltd. (72) Inventor Kenichi Sorimachi 1576 2 Kawasaki Furnace Materials Co., Ltd. F-term (reference) 4G033 AA02 AA03 AA06 AA14 AA15 AB02 AB10 AB24 AB25 4K051 AA02 BE00

Claims (3)

[Claims] 1. A resin composition comprising a resin, a pitch, and a metal powder as main components, further containing a room-temperature curing agent, a balance consisting of unavoidable impurities, and a ratio of the pitch, the resin to the total content of the pitch, the resin, and the metal powder. A graphite-containing binder for amorphous refractories, wherein the mass ratio of the total content is 0.6 to 0.9. 2. The graphite-containing binder for amorphous refractories according to claim 1, wherein the metal powder is a metal Si powder and / or a metal Al powder. 3. An amorphous refractory obtained by mixing a refractory material mainly composed of a refractory aggregate and graphite powder with the binder for graphite-containing amorphous refractory according to claim 1 or 2. ,
An amorphous refractory containing graphite, characterized in that the total solid content of the refractory contains 1.5% by mass or less of alumina cement and 0.1 to 1% by mass of resin.