JP2020158328A - Method for production of graphite-containing refractory - Google Patents

Abstract

To provide a production method for a graphite-containing refractory in which the spread of crack generating by heat stress is suppressed and high durability is obtained even in the use under such conditions that temperature rising and lowering are repeated for a long term like a lining refractory of a converter and further, even in the use such a condition that an inside temperature gradient is extremely large.SOLUTION: A graphite-containing refractory is produced by bonding a carbon fiber fabric y having 40-1,300 g in mass per 1 m2 to at least a part of the surface in the molding body x0 of a refractory raw material having a graphite content of 1-80 mass% via an adhesive a0, and further bonding the fabric y to at least a part of the surface of refractory body x composed of the molding body x0 via an adhesive-hardening material a composed of the adhesive a0. The difference between the thermal expansion coefficient of the adhesive-hardening material a and that of the refractory body x at temperature rising from normal temperature to 1,000°C is 2.0% or less, and the difference between the residual expansion rate of the adhesive-hardening material a and that of the refractory body x at temperature lowering from 1,000°C to normal temperature is also 2.0% or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing a graphite-containing refractory in which a carbon fiber woven fabric is adhered to the surface of the refractory body.

Equipment (refining containers, transport containers, etc.) used in the ironmaking process and steelmaking process at steelworks is lined with refractories so that it can withstand long-term use at high temperatures. Generally, magnesia carbon refractories are used for the lining of converters used in the refining process, and alumina, silicon carbide, and carbon refractories are used for the linings of topides and blast furnace pots used in the hot metal pretreatment process. Is used.
Refractory materials used for lining in these refining vessels and transport vessels are subject to mechanical impact due to charged materials, wear due to stirring of molten steel and molten slag, slag erosion due to molten slag, and sudden temperature changes during operation. Used under very harsh conditions. Therefore, in order to perform stable operation, it is necessary to use a refractory material having high durability that can withstand such harsh conditions.

In particular, the tuyere bricks that make up the tuyere of a converter have normal temperature gas (oxygen, hydrocarbon gas for cooling, etc.) flowing inside, and the inner surface is cooled by the normal temperature gas near the inside of the furnace. Since the outer surface is exposed to high temperature due to heat transfer from the molten steel in the furnace, the heat gradient inside the tuyere brick is extremely large, and the molten steel must be discharged after each charge of one charge of the converter is blown. The temperature drops due to the above, and large thermal fluctuations are repeated. The tuyere bricks installed in the converter reach a frequency of use of about 2500 to 4000 charges, and the extremely harsh conditions that the above-mentioned large thermal gradient is generated and large thermal fluctuations are repeated for each charge. Therefore, it is necessary to have high durability that can withstand use under such conditions. In addition, refractories for converter linings other than tuyere bricks (brick that constitutes the inner wall of the converter) are also used under harsh conditions where large thermal fluctuations are repeated as described above, so they are not as good as tuyere bricks. High durability is required.

As a technique for improving the durability of a refractory, Patent Document 1 describes that a unidirectional bundle or a woven fabric made of fibers having a tensile strength higher than that of the refractory is adhered to a part or the whole of the surface of the refractory. With this technology, refractories can be held for a long time with higher strength than before, the tensile strength of refractories can be improved, cracks and breakage can be suppressed, and the life and reliability of refractories can be improved. It is said that it can be done. Specifically, a bundle of fibers or a woven fabric is bonded to a nozzle through which molten steel flows inside, such as a long nozzle, a dipping nozzle, and a sliding nozzle used in a continuous steel casting process, with a phenol resin in a direction that restrains the outer surface. However, it is described that an antioxidant base layer and an antioxidant layer are arranged on the surface thereof. In these nozzles, the thermal expansion to the outer surface side when molten steel flows inside is restrained by the fiber bundle or woven fabric, and compressive stress is generated in the refractory that constitutes the nozzle, causing cracks or fracture. It is considered to be suppressing.

JP-A-2007-106618

However, in the continuous casting process in which the nozzle described in Patent Document 1 is used, molten steel for a plurality of charges blown in a converter is continuously cast, so that the cycle of temperature change of the nozzle used is a converter. The temperature difference from the molten steel flowing in the nozzle is not so large because it is longer than the refractory lining of the nozzle and the outer surface of the nozzle receives radiation from the molten steel stored in the container on the downstream side located below. On the other hand, the refractory lining of the converter (the brick that constitutes the inner wall of the converter), especially the tuyere brick that constitutes the tuyere, is used under extremely harsh conditions as described above. As a result of studies by the present inventors, it has been found that the technique described in Patent Document 1 cannot sufficiently enhance the durability of such a refractory.

Therefore, an object of the present invention solves the above-mentioned problems of the prior art, and is generated by thermal stress even when the refractory material in the lining of a converter is used under the condition that the temperature is repeatedly raised and lowered for a long period of time. Graphite content that suppresses the growth of cracks and provides high durability, and also provides high durability even when used under conditions with a very large internal temperature gradient, such as the tuyere bricks of converters. An object of the present invention is to provide a manufacturing method capable of stably manufacturing a refractory material.

As a result of repeated studies to solve the above problems, the present inventors adhere a carbon fiber woven fabric having a specific unit mass to the surface of the refractory body (molded body of the refractory raw material) via an adhesive. At the same time, make the thermal characteristics of the cured product of the adhesive and the refractory body a specific relationship, specifically, from the difference in the coefficient of thermal expansion between the two when the temperature is raised from room temperature to 1000 ° C and from 1000 ° C. It was found that a graphite-containing refractory having high durability can be obtained even in the extremely harsh usage environment as described above by setting the difference in the residual expansion coefficient between the two when the temperature is lowered to room temperature to a predetermined value or less. It was.

The present invention has been made based on such findings, and has the following gist.
[1] A molding process of molding a refractory raw material having a graphite content of 1 to 80% by mass to obtain a molded body (x ₀ ).
Adhesion of carbon fiber woven fabric (y) having a mass of 40 to 1300 g per 1 m ^{2 to} at least a part of the surface of the molded body (x ₀ ) obtained in the molding step via an adhesive (a ₀ ). Process and
The bonding step includes a drying step of drying the molded body (x ₀ ) to which the carbon fiber woven fabric (y) is bonded.
A carbon fiber woven fabric (y) is formed on at least a part of the surface of the refractory body (x) composed of the molded body (x ₀ ) via an adhesive cured product (a) composed of the adhesive (a ₀ ). 2. The difference between the coefficient of thermal expansion of the cured adhesive (a) and the coefficient of thermal expansion of the refractory body (x) when the temperature is raised from room temperature to 1000 ° C. Graphite that is 0% or less and the difference between the residual expansion coefficient of the cured adhesive (a) and the residual expansion coefficient of the refractory body (x) when the temperature is lowered from 1000 ° C to room temperature is 2.0% or less. A method for producing a graphite-containing refractory, which comprises obtaining a refractory containing refractory.

[2] A molding process of molding a refractory raw material having a graphite content of 1 to 80% by mass to obtain a molded body (x ₀ ).
A drying step of drying the molded body (x ₀ ) obtained in the molding step, and a drying step.
An adhesive step of adhering a carbon fiber woven fabric (y) having a mass of 40 to 1300 g per m ^{2 to} at least a part of the surface of the molded body (x ₀ ) that has undergone the drying step via an adhesive (a ₀ ). Have and
A carbon fiber woven fabric (y) is formed on at least a part of the surface of the refractory body (x) composed of the molded body (x ₀ ) via an adhesive cured product (a) composed of the adhesive (a ₀ ). 2. The difference between the coefficient of thermal expansion of the cured adhesive (a) and the coefficient of thermal expansion of the refractory body (x) when the temperature is raised from room temperature to 1000 ° C. Graphite that is 0% or less and the difference between the residual expansion coefficient of the cured adhesive (a) and the residual expansion coefficient of the refractory body (x) when the temperature is lowered from 1000 ° C to room temperature is 2.0% or less. A method for producing a graphite-containing refractory, which comprises obtaining a refractory containing refractory.

[3] A method for producing a graphite-containing refractory, which further comprises a step of reducing and firing a molded product (x ₀ ) that has undergone a drying step in the production method of the above [1] or [2].
[4] Adhesive is a carbon fiber woven fabric (y) having a weight of 40 to 1300 g per m ^{2 on} at least a part of the surface of a molded body (x ₀ ) of a refractory raw material having a graphite content of 1 to 80% by mass. It has a bonding process of bonding via (a ₀ ),
A carbon fiber woven fabric (y) is formed on at least a part of the surface of the refractory body (x) composed of the molded body (x ₀ ) via an adhesive cured product (a) composed of the adhesive (a ₀ ). 2. The difference between the coefficient of thermal expansion of the cured adhesive (a) and the coefficient of thermal expansion of the refractory body (x) when the temperature is raised from room temperature to 1000 ° C. Graphite that is 0% or less and the difference between the residual expansion coefficient of the cured adhesive (a) and the residual expansion coefficient of the refractory body (x) when the temperature is lowered from 1000 ° C to room temperature is 2.0% or less. A method for producing a graphite-containing refractory, which comprises obtaining a refractory containing refractory.

[5] In any of the above-mentioned production methods [1] to [4], the carbon fiber woven fabric (y) is a woven fabric in which carbon fiber bundles are oriented in two or more directions.
The carbon fiber bundle is a bundle of carbon fibers having a fiber diameter of 1 to 45 μm, and the number of carbon fibers per bundle is more than 100 and 120,000 or less.
In the bonding step, a graphite-containing material is characterized in that one or more layers of the carbon fiber woven fabric (y) are adhered to at least a part of the surface of the molded body (x ₀ ) via an adhesive (a ₀ ). How to manufacture refractories.
[6] A method for producing a graphite-containing refractory, wherein the adhesive (a ₀ ) is an oxide-based adhesive in any of the above-mentioned production methods [1] to [5].
[7] In any of the above-mentioned production methods [1] to [6], the refractory raw material contains 20 to 99% by mass of a magnesia raw material having a magnesia concentration of 90% by mass or more, and is characterized by having a graphite-containing refractory. Manufacturing method of goods.

[8] In any of the above-mentioned production methods [1] to [6], the refractory raw material contains 10 to 95% by mass of an alumina raw material having an alumina concentration of 70% by mass or more, and is characterized by having a graphite-containing refractory. Manufacturing method of goods.
[9] In the method for producing a graphite-containing refractory according to the above [8], the refractory raw material contains 1% by mass or more of a silicon carbide raw material having a silicon carbide concentration of 80% by mass or more.
[10] The graphite according to any one of the above [1] to [6], [8], and [9], wherein the refractory raw material contains 1 to 50% by mass of a silica raw material. Method for manufacturing refractory containing.
[11] In any of the above-mentioned production methods [1] to [10], the refractory raw material contains 10 to 90% by mass of refractory waste obtained by crushing a used refractory. How to make things.

[12] A tuyere brick having a gas passage hole (2) penetrating in the longitudinal direction from the upper surface to the bottom surface, which is an operating surface, and a plurality of brick constituent members (1) divided with the longitudinal direction as a dividing surface. Is a method of manufacturing tuyere bricks for refining vessels, which is formed by joining with an adhesive layer (b).
By any of the manufacturing methods [1] to [11] above, at least a part of the surface of the refractory body (x) made of the molded body (x ₀ ) is made of an adhesive (a ₀ ). A brick component (1) to which a carbon fiber woven fabric (y) is bonded via an adhesive cured product (a) is manufactured, and the plurality of manufactured brick components (1) are joined with an adhesive material (b). A method for manufacturing tuyere bricks for refining containers, which comprises obtaining tuyere bricks by doing so.
[13] Each brick component (1) manufactured in the manufacturing method of the above [12] has a gas passage hole (2) on one side surface of a refractory body (x) composed of a molded body (x ₀ ). A groove (4) forming a part of the refractory body is formed, and the surface of at least the upper part of the refractory body (x) is covered with the entire circumference of the refractory body (x). ), A method for producing a tuyere brick for a refractory container, which comprises adhering a carbon fiber woven fabric (y).

According to the present invention, since it has high fracture energy, the growth of cracks generated by thermal stress is suppressed even when it is used under the condition that the temperature is repeatedly raised and lowered for a long period of time like a refractory lining of a converter. Therefore, high durability can be obtained, and graphite-containing refractories with high durability can be stably manufactured even when used under conditions where the internal temperature gradient is extremely large, such as the tuyere bricks of converters. can do.

A flow chart showing an example of a manufacturing process of a graphite-containing refractory by the method of the present invention. An explanatory view showing an example of a procedure for adhering a carbon fiber woven fabric to four surfaces of a molded body in the bonding step of the present invention, and showing the procedure in the previous stage. Explanatory drawing showing the procedure following FIG. 2-1 Explanatory drawing showing a molded body in which two or more layers of carbon fiber woven fabrics are adhered to the surface. When manufacturing a tuyere brick by the method of the present invention In one embodiment, one of the brick constituent members constituting the tuyere brick is schematically shown, and FIG. 4 (A) is a perspective view and FIG. 4 (B). ) Is a plan view In the embodiment of FIG. 4, a plan view showing a tuyere brick constructed by assembling two brick components. Explanatory drawing which shows the preparation method of the sample for measurement for measuring the coefficient of thermal expansion and the coefficient of residual expansion of an adhesive cured product. A method for measuring the bending strength of a graphite-containing refractory in an example is shown. FIG. 7 (A) is an explanatory diagram schematically showing the implementation status of a three-point bending strength test, and FIG. 7 (B) is FIG. 7 (A). ) Schematic diagram showing the end face of the test piece A drawing showing an example of fracture energy (fracture energy of the example of the present invention) obtained from a load-displacement curve obtained in a three-point bending strength test in an example. A drawing showing another example of fracture energy (fracture energy of a comparative example) obtained from a load-displacement curve obtained in a three-point bending strength test in an embodiment. The evaluation test method of the erosion resistance of the graphite-containing refractory in the examples is shown, and FIG. 9A is an explanatory view schematically showing the implementation status of the test in a state where the test furnace and the tubular sample are vertically crossed. 9 (B) is a plan view of the tubular sample shown in FIG. 9 (A), and FIG. 9 (C) is one of the test pieces constituting the tubular sample shown in FIGS. 9 (A) and 9 (B). Perspective view shown A graph showing the wear rate when the tuyere bricks of the present invention and the conventional example obtained in the examples are used in a converter.

The first production method of the present invention, the molding process of the graphite content to obtain a molded body x ₀ by molding is from 1 to 80% by weight of the refractory material, the surface of the molded body x ₀ obtained in this molding step A bonding step of bonding the carbon fiber woven fabric y having a mass of 40 to 1300 g per 1 m ² to at least a part of the above via an adhesive a ₀ , and a molded body x ₀ to which the carbon fiber woven fabric y is bonded in this bonding step. Has a drying step of drying. Further, in the second production method of the present invention, after the molded body x ₀ is dried, a carbon fiber woven fabric is adhered to the surface of the molded body x ₀ , and the fire resistance has a graphite content of 1 to 80% by mass. a molding step of obtaining a molded body x ₀ by molding objects feedstock, a drying step of drying the molded body x ₀ obtained in this molding step, at least a portion of the surface of the molded body x ₀ passing through this drying step It has a bonding step of bonding carbon fiber woven fabric y having a mass of 40 to 1300 g per 1 m ² via an adhesive a ₀ . Further, the third production method of the present invention is to bond a carbon fiber woven fabric to a molded body x ₀ (dried molded body) obtained in advance, and is a refractory material having a graphite content of 1 to 80% by mass. It has a bonding step of bonding a carbon fiber woven fabric y having a mass of 40 to 1300 g per 1 m ^{2 to} at least a part of the surface of the raw material molded body x ₀ via an adhesive a ₀ .

In the present invention, by going through the above steps, at least a part of the surface of the refractory body x made of the molded body x ₀ is passed through the cured adhesive a made of the adhesive a _0. 2. The difference between the coefficient of thermal expansion of the cured adhesive a and the coefficient of thermal expansion of the refractory body x when the temperature is raised from room temperature to 1000 ° C. in the graphite-containing refractory to which the carbon fiber woven fabric y is adhered. A graphite-containing refractory whose difference between the residual expansion coefficient of the cured adhesive a and the residual expansion coefficient of the refractory body x when the temperature is lowered from 1000 ° C. to room temperature is 2.0% or less. obtain. Therefore, a refractory body x (molded body x ₀ ) and an adhesive cured product a (adhesive a ₀ ) having thermal expansion characteristics satisfying such conditions are appropriately selected, but in general, the refractory body x With respect to (molded body x ₀ ), an adhesive cured product a (adhesive a ₀ ) having a thermal expansion characteristic satisfying the above conditions is appropriately selected.

FIG. 1 shows an example of a manufacturing process in the first manufacturing method of the present invention.
In the molding step, an appropriate amount of binder is added to the refractory raw material and kneaded, and the kneaded product is filled in a mold and press-molded to obtain a molded body x ₀ (a molded product of the refractory raw material). As the binder, for example, phenol resin (main agent) + hexamine (hardener), carbon bond, ceramic bond and the like are used.
In the subsequent bonding step, the carbon fiber woven fabric y is bonded to the surface of the molded body x ₀ (molded product constituting the refractory body x) obtained in the molding step with the adhesive a ₀ .
In the subsequent drying step, the molded body x ₀ to which the carbon fiber woven fabric y is adhered is dried. This drying is usually performed at about 200 to 230 ° C. for the purpose of drying (curing) the molded body x ₀ , but it can also be performed for drying the adhesive a ₀ . Further, after drying (curing), reduction firing (caulking treatment) may be further performed to obtain product bricks (fired bricks).

Further, as in the second production method of the present invention, the carbon fiber woven fabric y may be bonded after the drying step of the molded body x ₀ is carried out, and then the adhesive is dried if necessary. May be done. Further, in this case as well, after drying (curing), further reduction firing (caulking treatment) may be performed to obtain product bricks (caulking treatment), and the reduction firing (caulking treatment) is performed before and after bonding the carbon fiber woven fabric. It may be done by any of.
Further, in some cases, as in the third manufacturing method of the present invention, a step of adhering the carbon fiber woven fabric y to the preliminarily obtained molded body x ₀ (dried molded body) is performed, and then it is necessary. Depending on the situation, the adhesive may be dried.
As described above, a graphite-containing refractory in which the carbon fiber woven fabric y is adhered to at least a part of the surface of the refractory body x composed of the molded body x ₀ via the adhesive cured product a composed of the adhesive a _0. You can get things.

The step of adhering the carbon fiber woven fabric y to the molded body x ₀ is carried out, for example, as follows. FIG. 2 shows an example of a procedure for adhering the carbon fiber woven fabric y to the four surfaces (side surfaces (1) to (4)) of the rectangular parallelepiped molded body x ₀ . In this example, as shown in FIG. 2-1 (A), a molded x ₀ placed on a flat place, one end of the carbon fiber woven fabric y with adhesive material 3 such as double-sided adhesive tape of the molded body x ₀ was adhered to the surface, applying an adhesive a ₀ on the surface of the carbon fiber woven fabric y as shown in FIG. 2-1 (B). The adhesive a ₀ may be applied to the molded body x ₀ . Then, as shown in Figure 2-2, such that the carbon fiber fabric y does not become wrinkled, while the molded body x ₀ is rotated 90 ° in a state of pulling the carbon fiber woven fabric y, the side surface of the molded body x ₀ (1 ) Is bonded to the carbon fiber woven fabric y via the adhesive a ₀ . As shown in FIG. 2-2, by repeating the application of the adhesive a ₀ to the surface of the carbon fiber woven fabric y (or the molded body x ₀ ) and the 90 ° rotation of the molded body x ₀ as described above, the molded body and sequentially adhering the carbon fiber woven fabric y to the side of _{x 0 (2) ~ (4} ). As a result, a refractory material obtained by adhering the carbon fiber woven fabric y to the four surfaces (side surfaces (1) to (4)) of the molded body x ₀ can be obtained.
Further, when the carbon fiber woven fabric y is constructed in two or more layers as shown in FIG. 3, the series of operations in FIG. 2-2 may be repeated twice or more.

The carbon fiber woven fabric y to be bonded to the surface of the molded body x ₀ via the adhesive a ₀ has a mass of 40 to 1300 g per 1 m ² , and preferably carbon fibers having a fiber diameter of 1 to 45 μm are bundled together. It is a carbon fiber woven fabric in which the carbon fiber bundles are oriented in two or more directions, and the carbon fiber bundle is composed of more than 100 carbon fibers and 120,000 or less carbon fibers per bundle. By adhering such a carbon fiber woven fabric y to the surface of the molded body x ₀ (refractory body x) via the adhesive a ₀ (adhesive cured product a), it is fire resistant via the adhesive cured product a. Since the object body x and the carbon fiber woven fabric y are integrated, the carbon fiber woven fabric y does not slip with respect to the refractory body x, which greatly increases the breaking energy of the entire refractory material and also has the effect of suppressing crack growth. improves.

If the mass of the carbon fiber woven fabric y per 1 m ² is less than 40 g, the carbon fiber woven fabric is too thin, so that the crack growth suppressing effect is not improved and the breaking energy is not increased. On the other hand, the mass of 1 m ² per carbon fiber fabric y is poor workability because of too thick carbon fiber fabric exceeds 1300 g, when adhering the carbon fiber woven fabric in the refractory body surface of the carbon fiber woven fabric and refractory body Since there is a gap between them, the crack growth suppressing effect is not improved, and the breaking energy does not increase in this case as well. Further, when the fiber diameter of the carbon fibers constituting the carbon fiber fabric y (carbon fiber bundle) is less than 1 μm, or when the number of carbon fibers per bundle of the carbon fiber bundle is 100 or less, the carbon fiber fabric y The mass per 1 m ² tends to be less than 40 g. On the other hand, when the fiber diameter of the carbon fibers constituting the carbon fiber woven fabric y (carbon fiber bundle) exceeds 45 μm, or when the number of carbon fibers per bundle of the carbon fiber bundles exceeds 120,000, the carbon fiber woven fabric y The mass per 1 m ² tends to exceed 1300 g.

The carbon fiber woven fabric y is one in which carbon fiber bundles are oriented in two or more directions, and the number of orientations is arbitrary. When the orientation direction of the carbon fiber bundle is one direction, the carbon fiber woven fabric cannot be formed, so that a graphite-containing refractory to which the carbon fiber woven fabric is adhered cannot be obtained.
The number of layers of the carbon fiber woven fabric y bonded to the surface of the molded body x ₀ via the adhesive a ₀ is arbitrary and may be one layer or two or more layers, but the carbon fiber woven fabric y has two or more layers. This is preferable because the effect of suppressing crack growth is further improved.
The carbon fiber woven fabric y may be adhered to the surface of the molded body x ₀ so as to cover the entire molded body x ₀ (refractory body x), but is particularly adhered only to the surface of the portion where cracks are likely to develop. May be good. In this case, the carbon fiber woven fabric y is adhered to the outer periphery of the portion and restrained so that cracks do not grow.

In the graphite-containing refractory produced by the present invention, it is important that the thermal properties of the cured adhesive a and the refractory body x have a specific relationship in addition to the constitution of the carbon fiber woven fabric y as described above. .. That is, (i) the difference between the coefficient of thermal expansion of the cured adhesive product a and the coefficient of thermal expansion of the refractory body x when the temperature is raised from room temperature to 1000 ° C. is 2.0% or less, and (ii). It is necessary that the difference between the residual expansion coefficient of the cured adhesive product a and the residual expansion coefficient of the refractory body x when the temperature is lowered from 1000 ° C. to room temperature is 2.0% or less.
If the difference in the coefficient of thermal expansion or the difference in the coefficient of residual expansion between the cured adhesive a and the refractory body x exceeds 2.0%, the graphite-containing refractory is used for a long period of time under conditions where large thermal gradients and thermal fluctuations occur. Then, the adhesiveness between the refractory body x and the carbon fiber woven fabric y decreases, and the carbon fiber woven fabric y easily peels off from the refractory body x, the breaking energy decreases during use, and the crack growth is suppressed by the decrease in crack resistance. The effect will not be obtained. In particular, the refractory lining of the converter (the bricks that make up the inner wall of the converter), especially the tuyere bricks that make up the tuyere of the converter, are used under extremely harsh conditions as described above, so they are used for a long period of time. Durability cannot be obtained.

Although there is no particular restriction on the type of adhesive a ₀ for use in the present invention, to maintain the difference of the difference and the residual expansion rate of thermal expansion of the cured adhesive a refractory material body x to 2.0% From this point of view, an oxide-based adhesive that does not easily cause a decomposition reaction in a high temperature range is preferable. That is, the cured product of the oxide-based adhesive does not undergo a decomposition reaction even in a high temperature range of 1000 ° C. or higher, and the adhesive does not undergo significant thermal expansion. Therefore, the temperature of the graphite-containing refractory is increased as in a converter. The difference in the coefficient of thermal expansion and the difference in the residual expansion coefficient between the refractory body x and the adhesive cured product a can be suppressed to 2.0% or less even when used under conditions where the temperature is repeatedly lowered, and the refractory body x and the carbon fiber An oxide-based adhesive is particularly preferable because the adhesiveness of the woven fabric y can be maintained (the carbon fiber woven fabric y does not easily come off).

The adhesive a ₀ desirably have a heat resistance at 1000 ° C. or higher, and thus alumina is a powder, silica, magnesia, is composed mainly of one or more such zirconia particularly preferred. As such an adhesive (oxide adhesive), for example, "Aron Ceramic D" (trade name) manufactured by Toa Synthetic Co., Ltd., "Inorganic heat resistant adhesive TB3732" (trade name) manufactured by ThreeBond Co., Ltd., Shinagawa Riff Examples thereof include "SIM # 512" (trade name) manufactured by Lactories Co., Ltd.
When the coefficient of thermal expansion and the coefficient of residual expansion of the refractory body x (molded body x ₀ ) are determined, the difference in the coefficient of thermal expansion and the difference in the coefficient of residual expansion between the refractory body x and the adhesive cured product a are 2. Adhesive a ₀ such that it is 0% or less is selected.

Next, the composition of the refractory raw material (the raw material constituting the refractory body x) will be described.
The graphite content of the refractory raw material is 1 to 80% by mass, and if the graphite content is less than 1% by mass, the occurrence of cracks due to thermal stress cannot be suppressed, and the crack resistance is significantly lowered. On the other hand, if the graphite content exceeds 80% by mass, the properties such as erosion resistance, crack resistance, and fracture energy may be adversely affected depending on the material of the refractory body x.
Generally, the lining of the converter used in the refining process (including the tuyere) contains magnesia-carbon refractory (graphite made from magnesia raw material as an aggregate), which is a refractory mainly composed of magnesia and carbon. Refractory) is used. When the refractory body x is a magnesia-carbon refractory, the refractory raw material preferably contains 20 to 99% by mass of a high-purity magnesia raw material having a magnesia concentration of 90% by mass or more, and thus by thermal erosion. It can be a refractory that can withstand erosion of converter slag while suppressing cracking. If the content of the magnesia raw material is less than 20% by mass, the converter slag cannot withstand erosion and the erosion resistance is significantly reduced. As the carbon raw material, scaly graphite or the like is generally used.

In general, the topede and blast furnace lining used in the hot metal pretreatment process are made of alumina, silicon carbide, and carbon refractories, which are refractories mainly composed of alumina, silicon carbide, and carbon (alumina raw material, silicon carbide). Graphite-containing refractories made from raw materials as aggregates) and alumina / silicon carbide / silica / carbon refractories (alumina raw materials, silicon carbide raw materials, silica) which are refractories mainly composed of alumina, silicon carbide, silica and carbon. A graphite-containing refractory whose raw material is aggregate) is used. When the refractory body x is an alumina / silicon carbide / carbonaceous refractory or an alumina / silicon carbide / silica / carbon refractory, the refractory raw material is 10 to 10 high-purity alumina raw materials having an alumina concentration of 70% by mass or more. It is preferably contained in an amount of 95% by mass, which can withstand the erosion of the hot metal pretreatment slag and suppress the cracking due to thermal spalling. If the content of the alumina raw material is less than 10% by mass, the erosion of the hot metal pretreatment slag cannot be tolerated, the slag permeates into the matrix portion of the refractory body x (brick), and the erosion resistance is lowered. On the other hand, if the content of the alumina raw material exceeds 95% by mass, the occurrence of cracks due to thermal spalling cannot be suppressed, and the crack resistance is lowered.

Further, when the refractory body x is an alumina / silicon carbide / carbonaceous refractory or an alumina / silicon carbide / silica / carbon refractory, the refractory raw material is high-purity silicon carbide having a silicon carbide concentration of 80% by mass or more. It is preferable that the raw material is contained in an amount of 1% by mass or more. By containing 1% by mass or more of the silicon carbide raw material, the oxidation of graphite in the air atmosphere can be suppressed, so that high crack resistance can be maintained. If the content of the silicon carbide raw material is less than 1% by mass, the oxidation of graphite in the air atmosphere cannot be suppressed, so that the crack resistance is lowered.
When the refractory body x is alumina, silicon carbide, silica, or carbonaceous refractory, the refractory raw material preferably contains 1 to 50% by mass of the silica raw material, whereby high crack resistance and high erosion resistance. Both sex can be achieved. When the content of the silica raw material is less than 1% by mass, the amount of expansion is small and fine cracks are not generated, so that the thermal shock fracture resistance does not increase and the crack resistance tends to decrease. On the other hand, if the content of the silica raw material exceeds 50% by mass, the erosion resistance is significantly deteriorated.

Further, when the refractory body x is a refractory containing silica, silicon carbide and carbon as main components of silica, silicon carbide and carbonaceous refractory, the refractory raw material has a high purity of silicon carbide concentration of 80% by mass or more. It is preferable to contain 1% by mass or more of the silicon carbide raw material and 1 to 50% by mass of the silica raw material, whereby both high crack resistance and high erosion resistance can be achieved. By containing 1% by mass or more of the silicon carbide raw material, the oxidation of graphite in the air atmosphere can be suppressed, so that high crack resistance can be maintained. If the content of the silicon carbide raw material is less than 1% by mass, the oxidation of graphite in the air atmosphere cannot be suppressed, so that the crack resistance is lowered. Further, when the content of the silica raw material is less than 1% by mass, the expansion amount is small and fine cracks are not generated, so that the thermal shock fracture resistance does not increase and the crack resistance tends to decrease. On the other hand, if the content of the silica raw material exceeds 50% by mass, the erosion resistance is significantly deteriorated.

Here, as the alumina raw material, for example, one or more kinds of van shale, white alumina, brown alumina and the like are used. Further, as the silicon carbide raw material, for example, one or more kinds such as green silicon carbide and black silicon carbide are used. Further, as the silica raw material, for example, one or more kinds such as pyrophyllite and mullite are used.
The refractory raw material can further contain (blend) a metal powder raw material for the purpose of increasing the durability while suppressing the amount of heat radiated from the steelmaking container. Examples of the metal powder raw material include metal Si, metal Al, metal Al—Si, Al ₄ SiC ₄ , B ₄ C, and the like, and one or more of these can be contained. The content of the metal powder raw material is not particularly specified, but is usually preferably about 1 to 5% by mass. If the content (blending amount) of the metal powder raw material is less than 1% by mass, the effect of improving the durability by blending the metal powder raw material cannot be sufficiently obtained, while if it exceeds 5% by mass, the strength becomes high. If it is too much, cracks are likely to occur when used in an actual machine, and the bricks are likely to be cracked, which may reduce the number of times of use in the actual machine.

The refractory raw material can contain about 10 to 90% by mass of refractory scraps obtained by crushing a used refractory as an aggregate raw material. In particular, when the refractory body x is an alumina / silicon carbide / carbon refractory (including the case of an alumina / silicon carbide / silica / carbon refractory containing a silica raw material; the same applies hereinafter), it has been used. Alumina / silicon carbide / carbon refractory (including the case of alumina / silicon carbide / silica / carbon refractory containing silica raw material; the same applies hereinafter) is used as an aggregate raw material. It can be preferably used.
When the refractory waste is contained in this way, the rest of the refractory raw material is an unused raw material (virgin raw material).

The content of refractory waste obtained by crushing used alumina / silicon carbide / carbon refractory in the refractory raw material of the refractory body x made of alumina / silicon carbide / carbon refractory is 10 to 90. When it is set to% by mass, crack resistance and erosion resistance equivalent to those of a graphite-containing refractory using only a virgin raw material can be obtained. The reason is that the refractory waste raw material has a lower purity than the virgin raw material, but by using the refractory waste raw material and the virgin raw material together, the erosion resistance of the Al ₂ O ₃ component in the refractory waste raw material can be improved. It can be mentioned that a significant decrease can be suppressed. On the other hand, when the content of the refractory waste is more than 90% by mass, the content of the virgin raw material is too small, so that it is not possible to suppress a significant decrease in the corrosion resistance of the Al ₂ O ₃ component in the refractory waste raw material. Further, when the content of the refractory waste is less than 10% by mass, the reuse rate of the refractory waste is too low, so that the cost of treating the refractory waste as industrial waste increases significantly.

The graphite-containing refractory produced by the present invention is particularly suitable for a converter lining refractory because it can suppress the growth of cracks generated by thermal stress even under conditions where temperature rise and fall are repeated. Furthermore, the graphite-containing refractory of the present invention can obtain high durability even when used under conditions where the internal temperature gradient is very large, and is therefore particularly suitable for tuyere bricks among refractory linings of converters. Is.
4 and 5 show an embodiment when producing tuyere bricks by the method of the present invention. 4A and 4B schematically show one of the brick constituent members constituting the tuyere brick, FIG. 4A is a perspective view, and FIG. 4B is a plan view. FIG. 5 is a plan view showing a tuyere brick constructed by assembling two brick components.

The tuyere brick has a gas through hole 2 penetrating in the longitudinal direction (vertical direction) from the upper surface 5 to the bottom surface 6 which is an operating surface, and when installed in the tuyere portion, the gas through hole 2 A metal pipe is fitted into the metal pipe, and the inside of the metal pipe serves as a gas passage hole.
The tuyere brick is composed of a plurality of brick constituent members 1 divided with the longitudinal direction of the gas passage as a dividing surface. In the present embodiment, the tuyere brick is composed of a pair of brick constituent members 1, and a groove 4 for gas passage is formed on one side surface of each brick constituent member 1.
In this method of manufacturing tuyere bricks, first, as shown in FIG. 4, a carbon fiber woven fabric y is adhered to at least a part of the surface of a molded body x ₀ to form each brick component 1 with an adhesive a _0. A brick component 1 in which a carbon fiber woven fabric y is adhered to at least a part of the surface of a refractory body x composed of a molded body x ₀ via an adhesive cured product a composed of an adhesive a _0. To make.

In the production of each brick component 1 in the present embodiment, carbon fibers are placed on the surface of a predetermined range on the upper side of the molded body x ₀ (a predetermined range on the upper side in contact with the upper surface 5 which is an operating surface) via an adhesive a _0. The woven fabric y is glued. The carbon fiber woven fabric y is adhered so as to cover the entire circumference (the entire circumference of the above-mentioned predetermined range) of the molded body x ₀ including the groove 4 for gas passage. The carbon fiber woven fabric y may be provided so as to cover the entire length of the molded body x ₀ , but the tuyere brick has a predetermined range on the upper side (in this range, the outer surface temperature of the tuyere brick is about 800 to 1000 ° C. , Especially, thermal stress is likely to occur), and cracks are particularly likely to occur. Therefore, it is necessary to provide at least a predetermined range on the upper side as in the present embodiment.
As shown in FIG. 5, the pair of brick constituent members 1 produced in this manner are assembled so that the gas passage holes 2 are formed by the grooves 4 of both, and the mating surfaces thereof are bonded materials such as mortar b. A tuyere brick can be obtained by joining with (adhesive layer).

The graphite-containing refractory produced in the present invention can be used as a refractory for various facilities and containers, and is particularly suitable as a refractory for lining refractories and transport containers used in steelworks. In particular, it is suitable as a refractory material for the lining of a converter, which is in a very harsh usage environment, and is particularly suitable as a tuyere brick constituting a tuyere portion.

A graphite-containing refractory in which a carbon fiber woven fabric was adhered to the surface of the refractory body via an adhesive cured product was produced by the process shown in FIG. Adhesion of the carbon fiber woven fabric to the surface of the molded body was carried out by the procedure as shown in FIG. In kneading and molding the refractory raw material, 3% by mass of phenol resin and 0.3% by mass of hexamine were blended as a binder by externally covering the refractory raw material.
The coefficient of thermal expansion and the coefficient of residual expansion of the refractory body and the cured adhesive were measured according to the method described in JIS R2207 for the measurement sample prepared as follows.
For the refractory body, a cylindrical sample having a diameter of 40 mm and a height of 40 mm was cut out by a boring machine and used as a measurement sample.

For the cured adhesive, a measurement sample was prepared by the following method.
The oxide-based adhesive has fluidity by preparing a stock solution of the oxide-based adhesive and a diluting alcohol, and adding 3 mass% of the diluted alcohol to the stock solution of the oxide-based adhesive. Diluted. Next, prepare a horizontal plate made of polyvinyl chloride having a thickness of 80 × 80 × 3 mm and a pipe made of polyvinyl chloride having an inner diameter of 40 mm, a height of 40 mm and a thickness of 3 mm, and on the horizontal plate as shown in FIG. A pipe was erected and fixed to the pipe, and an oxide-based adhesive was poured into the pipe to fill it. After curing this oxide-based adhesive in the atmosphere, only the pipe that became the outer frame of the adhesive was removed to prepare a sample for measurement.

After the refractory body and the sample for measuring the cured adhesive were placed in the furnace, the temperature was raised to 1000 ° C. at a heating rate of 5 ° C./min and held for 1 hour, and then cooled to room temperature. The height of the measurement sample before the temperature rise is L ₀ , the height of the measurement sample held at 1000 ° C is L ₁ , and the height of the measurement sample after refractory cooling is L ₂ , based on the following formula. The coefficient of thermal expansion and the coefficient of residual expansion of the refractory body and the cured adhesive were calculated.
Coefficient of thermal expansion (%) = (L _{1 −} L ₀ ) / L ₀ × 100
Residual expansion coefficient (%) = (L _2- L ₀ ) / L ₀ × 100

The bending strength, fracture energy, erosion resistance, and crack resistance of the produced graphite-containing refractory were evaluated by the following methods. Further, the erosion resistance and crack resistance of the refractory molded product before adhering the carbon fiber woven fabric shown in Table 1 were also evaluated by the same method.
As for the bending strength, as shown in FIG. 7 (test method), a test piece (test piece size: 40 mm × 40 mm) in which a carbon fiber woven fabric is adhered to all side surfaces of the refractory body in the longitudinal direction via an oxide adhesive. × 160 mm), the center-to-center distance was 100 mm, the load application speed was 0.5 mm / min, and the measurement was performed in accordance with the three-point bending test method described in JIS R2213. Note that FIG. 7B schematically shows the end faces of the test pieces of FIG. 7A.

Regarding the fracture energy, as shown in FIGS. 8-1 and 8-2, the displacement of 1 mm from the reference position is based on the position showing the first peak value in the load-displacement curve obtained by the three-point bending strength test. Evaluated by the area of the range. Note that FIG. 8-1 shows an example of the breaking energy obtained from the load-displacement curve of the example of the present invention, and FIG. 8-2 shows the load-displacement curve of the comparative example in which the carbon fiber woven fabric is not adhered to the surface. Each example of the breaking energy is shown.
As shown in FIG. 9 (test method), the erosion resistance was measured by the lining method using a high-frequency induction furnace and evaluated based on the erosion resistance. In the test by the lining method, the test temperature was 1650 ° C., the temperature holding time was 4 hours, and the synthetic slag having the composition shown in Table 2 was added every hour, and the amount of erosion of the working surface was measured after cooling. Then, from the amount of erosion, the erosion index was obtained with the amount of erosion of Invention Formulation Examples 1-3 in Table 1 as 100. As the test piece, as shown in FIG. 9C, a carbon fiber woven fabric having a carbon fiber woven fabric adhered to all side surfaces of the refractory body in the longitudinal direction via an oxide adhesive was used. Note that FIG. 9 (A) is an explanatory view schematically showing the test implementation status in a state in which the test furnace and the tubular sample are cross-sectionally crossed, and FIG. 9 (B) is the tubular sample shown in FIG. 9 (A). A plan view and FIG. 9C is a perspective view showing one of the test pieces constituting the tubular sample shown in FIGS. 9A and 9B.

Regarding crack resistance, after measuring the dynamic elastic modulus E ₀ in the longitudinal direction of a 40 × 40 × 200 mm sample according to the ultrasonic pulse method shown in JIS R1605, heating at 1500 ° C. for 10 minutes and cooling with water for 5 minutes. The process of cooling the atmosphere for 10 minutes as one cycle was repeated 3 times, and after the 3 times, the dynamic elastic modulus E ₃ was measured again by the above method, and the change rate E ₃ / E ₀ of the dynamic elastic modulus before and after the test was measured. It was evaluated as an index. As the test piece, a material in which a carbon fiber woven fabric was adhered to all side surfaces of the refractory body in the longitudinal direction via an oxide adhesive was used.

A refractory molded product using a magnesia raw material as an aggregate, that is, a refractory main body before adhering a carbon fiber woven fabric, was manufactured by blending the raw materials as shown in Table 1, and their erosion resistance and crack resistance were evaluated. .. The results are also shown in Table 1.
As shown in Invention Formulation Examples 1-1 to Invention Formulation Examples 1-7 in Table 1, when the graphite content is 1 to 80% by mass, the erosion resistance and crack resistance are good, but the comparative formulation examples As shown in 1-1, when the graphite content is less than 1% by mass, the crack resistance is significantly lowered. Further, as shown in Comparative Formulation Example 1-2, when the graphite content is more than 80% by mass, the erosion resistance is significantly lowered.
Further, as shown in Invention Formulation Examples 1-1 to Invention Formulation Example 1-7, the content of the magnesia raw material (magnesia concentration 100% by mass in the case of Table 1) is 20 to 99 in the formulation of the magnesia-carbon raw material. If it is by mass%, the erosion resistance and crack resistance are good. From the above, in order to achieve both erosion resistance and crack resistance of refractories, the graphite content must be 1 to 80% by mass, and in the case of magnesia carbonaceous raw materials, magnesia It can be seen that it is appropriate to set the content of the raw material to 20 to 99% by mass.

Tables 3 to 9 show the configurations and characteristics (bending strength, fracture energy, erosion resistance) of graphite-containing refractories (graphite-containing refractories in which a carbon fiber woven fabric is adhered to the surface of the refractory body) of the invention examples and comparative examples. , Crack resistance).
The examples in Table 3 investigated the effects of the mass per 1 m ^{2 of the} carbon fiber woven fabric adhered to the refractory body on the bending strength, fracture energy / crack resistance, and erosion resistance of the graphite-containing refractory. is there. The relationship between the number of carbon fibers per bundle of carbon fiber bundles constituting the carbon fiber woven fabric and the mass per 1 m ^{2 of the} carbon fiber woven fabric was also investigated. In this embodiment, carbon fiber woven fabrics in which 100 to 150,000 carbon fibers (fiber diameter 7 μm) are bundled and carbon fiber bundles are oriented in two directions and have different masses per 1 m ² are used as magnesia carbon fiber fireproof. It was adhered to the surface of the object (fireproof object body) via an adhesive cured product with an oxide-based adhesive.

As shown in Invention Examples 2-1 to 2-8 (and Invention Example 3-2 described later), when the mass of the carbon fiber woven fabric per 1 m ² is 40 to 1300 g, high bending strength and breaking energy. Crack resistance is obtained. Further, when the number of carbon fibers per bundle of the carbon fiber bundles constituting the carbon fiber woven fabric is more than 100 and 120,000 or less, the mass of the carbon fiber woven fabric per 1 m ² is 40 to 1300 g, which is a high bending ratio. Strength, breaking energy and crack resistance are obtained.
On the other hand, as shown in Comparative Example 2-1 when the number of carbon fibers per bundle of carbon fiber bundles constituting the carbon fiber woven fabric is 100 or less, the mass of the carbon fiber woven fabric per 1 m ² is less than 40 g. Since the carbon fiber woven fabric is too thin, high bending strength, breaking energy and crack resistance cannot be obtained.

Further, as shown in Comparative Example 2-2, when the number of carbon fibers per bundle of the carbon fiber bundles constituting the carbon fiber woven fabric exceeds 120,000, the mass of the carbon fiber woven fabric per 1 m ² exceeds 1300 g. Therefore, since the carbon fiber woven fabric is too thick, the workability is poor, and a gap is formed between the carbon fiber woven fabric and the main body of the fireproof material, so that high bending strength, breaking energy, and crack resistance cannot be obtained. Further, as shown in Comparative Example 2-3, since the carbon fiber woven fabric cannot be formed only by orienting the carbon fiber bundles in one direction, it is impossible to produce a graphite-containing refractory to which the carbon fiber woven fabric is adhered. Met.
From the above, it can be seen that high bending strength, fracture energy, and crack resistance can be obtained by setting the mass per 1 m ^{2 of the} carbon fiber woven fabric to be adhered to the refractory body to 40 to 1300 g. Further, in order to make the mass per 1 m ^{2 of the} carbon fiber woven fabric 40 to 1300 g, the number of carbon fibers per bundle of the carbon fiber bundles constituting the carbon fiber woven fabric should be more than 100 and 120,000 or less. It turns out that is preferable.

In the examples of Table 4, the relationship between the fiber diameter of the carbon fibers constituting the carbon fiber woven fabric (carbon fiber bundle) adhered to the fireproof material body and the mass per 1 m ^{2 of the} carbon fiber fabric was investigated, and the fireproof material body was used. The effects of the mass and the number of layers per 1 m ^{2 of the} bonded carbon fiber woven fabric on the bending strength, breaking energy / crack resistance, and erosion resistance of the graphite-containing refractory material were investigated. In this embodiment, the fiber diameters of the carbon fibers constituting the carbon fiber woven fabric (carbon fiber bundle) are set to 0.5 μm, 1 μm, 7 μm, 15 μm, 23 μm, 45 μm, and 50 μm, and 60,000 carbon fibers are bundled together. bonding two directions oriented 1 m ² per mass different carbon fiber fabric of carbon fiber bundles, magnesia-carbon refractories through the adhesive cured by oxide-based adhesive to the surface of the (refractory body) did. The number of layers of the carbon fiber woven fabric adhered to the refractory body was set to 1 to 3.

As shown in Invention Examples 3-1 to 3-7, when the fiber diameter of the carbon fibers constituting the carbon fiber woven fabric (carbon fiber bundle) is 1 to 45 μm, the mass of the carbon fiber woven fabric per 1 m ² is 40 to. It weighs 1300 g and has high bending strength, breaking energy and crack resistance. Further, as shown in Invention Examples 3-1 to 3-7, even if the number of layers of the carbon fiber woven fabric is one, sufficient bending strength, breaking energy and crack resistance are obtained, but 1 m of the carbon fiber woven fabric is obtained. If the mass per ^two is the same, the higher the number of layers of the carbon fiber woven fabric, the higher the bending strength, the breaking energy, and the crack resistance.

On the other hand, as shown in Comparative Example 3-1 when the fiber diameter of the carbon fibers constituting the carbon fiber woven fabric (carbon fiber bundle) is less than 1 μm, the mass of the carbon fiber woven fabric per 1 m ² is less than 40 g, and the carbon fiber woven fabric Is too thin, so high bending strength, breaking energy and crack resistance cannot be obtained. Further, as shown in Comparative Example 3-2, when the fiber diameter of the carbon fibers constituting the carbon fiber woven fabric (carbon fiber bundle) is more than 45 μm, the mass per 1 m ^{2 of} the carbon fiber woven fabric is more than 1300 g, and the carbon fiber is thick. Since it is too much, the workability is poor, and a gap is formed between the carbon fiber fabric and the fireproof material, and high bending strength, breaking energy, and crack resistance cannot be obtained.
From the above, in order to obtain high bending strength, breaking energy, and crack resistance by setting the mass per 1 m ^{2 of the} carbon fiber woven fabric to be adhered to the fireproof body to 40 to 1300 g, the carbon fiber woven fabric It can be seen that it is preferable that the fiber diameter of the carbon fibers constituting the (carbon fiber bundle) is 1 to 45 μm. Further, it can be seen that when the number of layers of the carbon fiber woven fabric is two or more, higher bending strength, breaking energy and crack resistance can be obtained.

In the examples of Table 5, the difference between the coefficient of thermal expansion of the refractory body and the cured adhesive (the coefficient of thermal expansion when the temperature is raised from room temperature to 1000 ° C.) and the residual expansion rate (the temperature is lowered from 1000 ° C. to room temperature). The effect of the difference in the coefficient of residual expansion) on the bending strength, breaking energy / crack resistance, and erosion resistance of the graphite-containing refractory was investigated. In this embodiment, a carbon fiber woven fabric (mass 500 g per 1 m ² ) in which 60,000 carbon fibers (fiber diameter 7 μm) are bundled and carbon fiber bundles are oriented in two directions is subjected to thermal expansion rate and residual expansion. It was adhered to the surface of magnesia-carbon fire-resistant material (fire-resistant material body) via an adhesive cured product with oxide-based adhesives having different coefficients.
In Table 5, a negative value of the residual expansion coefficient indicates that the cured adhesive product has shrunk, and the difference between the residual expansion coefficient of the refractory body and the cured adhesive product is 1. 0%, Inventive Example 4-2 is 2.0%, Comparative Example 4-1 is 3.0%, Comparative Example 4-2 is 4.0%, and Comparative Example 4-3 is 1.5%.
As shown in Invention Example 3-2, Invention Example 4-1 and Invention Example 4-2, when the difference in the coefficient of thermal expansion and the difference in the residual expansion rate between the refractory body and the cured adhesive is 2.0% or less. Since the adhesiveness between the refractory body and the carbon fiber woven fabric can be maintained, the carbon fiber woven fabric does not peel off from the refractory body, and therefore high bending strength, breaking energy, and crack resistance are obtained.

On the other hand, as shown in Comparative Examples 4-1 to 4-3, when the difference in the coefficient of thermal expansion and / and the difference in the residual expansion rate between the refractory body and the cured adhesive product exceeds 2.0%. Since the adhesiveness between the refractory body and the carbon fiber woven fabric cannot be maintained and the carbon fiber woven fabric is peeled off from the refractory body, high bending strength, breaking energy and crack resistance cannot be obtained.
From the above, in order to maintain the adhesiveness between the refractory body and the carbon fiber fabric and obtain high bending strength, breaking energy and crack resistance, the coefficient of thermal expansion between the refractory body and the cured adhesive (from room temperature to 1000). The difference between the difference in the coefficient of thermal expansion when the temperature is raised to ° C. and the difference in the residual expansion rate (the coefficient of residual expansion when the temperature is lowered from 1000 ° C to room temperature) must be 2.0% or less. It can be seen that an oxide-based adhesive is preferable as the adhesive for adhering the carbon fiber woven fabric to the refractory body.

The examples in Table 6 show the alumina / silica / silicon carbide / carbonic refractory (alumina raw material, silicon carbide raw material, graphite-containing refractory using silica raw material as aggregate) used for the lining of the hot metal pretreatment container. The effects of the composition on the bending strength, fracture energy / crack resistance, and erosion resistance of graphite-containing refractories were investigated. In this embodiment, a carbon fiber woven fabric (mass 500 g per 1 m ² ) in which 60,000 carbon fibers (fiber diameter 7 μm) are bundled and the carbon fiber bundles are oriented in two directions is formed of alumina, silica, silicon carbide, and the like. It was adhered to the surface of the carbon-based fire-resistant material (the main body of the fire-resistant material) via an adhesive cured product using an oxide-based adhesive.
As shown in Invention Examples 5-1 to 5-7, the content of the alumina raw material was 10 to 95% by mass, the content of the silica raw material was 1 to 50% by mass, and the graphite content was 1 to 80% by mass. In this case, high bending strength, fracture energy and crack resistance are obtained.

On the other hand, as shown in Comparative Example 5-1, when the content of the alumina raw material is less than 10% by mass, the content of the silica raw material is less than 1% by mass, and the graphite content is more than 80% by mass, the fracture occurs. Both energy and erosion resistance are significantly reduced. Further, as shown in Comparative Example 5-2, when the content of the alumina raw material is more than 95% by mass, the content of the silica raw material is less than 1% by mass, and the graphite content is less than 1% by mass, the fracture energy and crack resistance Has dropped significantly.
From the above, in alumina / silica / silicon carbide / carbon refractories, the content of the alumina raw material is 10 to 95% by mass, the content of the silica raw material is 1 to 50% by mass, and the graphite content is 1 to 80% by mass. If it is set to%, it can be seen that both high erosion resistance and high fracture energy / crack resistance can be achieved.

Examples in Table 7 are alumina / silica / silicon carbide / carbon refractories (alumina raw material, silicon carbide raw material, graphite-containing refractory using silica raw material as aggregate) used for the lining of the hot metal pretreatment container. For graphite-containing refractories using refractory scraps obtained by crushing used alumina, silica, silicon carbide, and carbon refractories as aggregate raw materials, the refractory scrap content is the bending of graphite-containing refractories. The effects on strength, fracture energy / crack resistance, and erosion resistance were investigated. In this embodiment, a carbon fiber woven fabric (mass 500 g per 1 m ² ) in which 60,000 carbon fibers (fiber diameter 7 μm) are bundled and the carbon fiber bundles are oriented in two directions is formed of alumina, silica, silicon carbide, and the like. It was adhered to the surface of the carbon-based fire-resistant material (the main body of the fire-resistant material) via an adhesive cured product using an oxide-based adhesive.

As shown in Invention Examples 6-1 to 6-3, the content of refractory waste was 10 to 90% by mass, the content of silica raw material was 1% by mass or more, and the graphite content was 1 to 80% by mass. In this case, the same level of fracture energy, crack resistance and erosion resistance as those of graphite-containing refractories using only the virgin raw materials shown in Table 6 are obtained.
On the other hand, as shown in Comparative Example 6-1, when the refractory waste content is more than 90% by mass, the silica raw material content is less than 1% by mass, and the graphite content is less than 1% by mass, the fracture energy. Crack resistance and erosion resistance are significantly reduced.
Based on the above, the graphite-containing refractory made from the refractory scraps obtained by crushing used alumina, silica, silicon carbide, and carbon refractory materials has a refractory waste content of 10. If the content of the silica raw material is 1% by mass or more and the graphite content is 1 to 80% by mass, the fracture energy and crack resistance can be maintained high, and the graphite content using only the virgin raw material can be maintained. It can be seen that it has the same erosion resistance as refractories.

In the examples shown in Table 8, the composition of an alumina / silicon carbide / carbon refractory (alumina raw material, a graphite-containing refractory using a silicon carbide raw material as an aggregate) is the bending strength, breaking energy / resistance of the graphite-containing refractory. The effect on crackability and erosion resistance was investigated. In this embodiment, a carbon fiber woven fabric (mass 500 g per 1 m ² ) in which 60,000 carbon fibers (fiber diameter 7 μm) are bundled and the carbon fiber bundles are oriented in two directions is made of alumina, silicon carbide, and carbon. It was adhered to the surface of the fire-resistant material (the main body of the fire-resistant material) via an adhesive cured product using an oxide-based adhesive.
As shown in Invention Examples 7-1 to 7-3, when the content of the alumina raw material is 10 to 95% by mass and the graphite content is 1 to 80% by mass, high bending strength, fracture energy and crack resistance And erosion resistance is obtained.

On the other hand, as shown in Comparative Example 7-1, when the content of the alumina raw material is less than 10% by mass and the graphite content is more than 80% by mass, the fracture energy and the erosion resistance are significantly lowered. Further, as shown in Comparative Example 7-2, when the content of the alumina raw material is more than 95% by mass and the graphite content is less than 1% by mass, the fracture energy and crack resistance are significantly lowered.
From the above, if the content of the alumina raw material is 10 to 95% by mass and the graphite content is 1 to 80% by mass in the alumina / silicon carbide / carbon refractory, high fracture energy, crack resistance and melting resistance. It can be seen that loss is obtained.

In the examples of Table 9, the composition of silica / silicon carbide / carbonic refractory (silica raw material, graphite-containing refractory using silicon carbide raw material as aggregate) is the bending strength, breaking energy / resistance of the graphite-containing refractory. The effect on crackability and erosion resistance was investigated. In this embodiment, a carbon fiber woven fabric (mass 500 g per 1 m ² ) in which 60,000 carbon fibers (fiber diameter 7 μm) are bundled and carbon fiber bundles are oriented in two directions is made of silica, silicon carbide, or carbon. It was adhered to the surface of the fire-resistant material (the main body of the fire-resistant material) via an adhesive cured product using an oxide-based adhesive.

As shown in Invention Example 8-1 and Invention Example 8-2, when the content of the silica raw material is 1 to 50% by mass and the graphite content is 1 to 80% by mass, high bending strength, breaking energy and crack resistance And erosion resistance is obtained.
On the other hand, as shown in Comparative Example 8-1, when the content of the silica raw material is less than 1% by mass and the graphite content is more than 80% by mass, the fracture energy and crack resistance are lowered. Further, as shown in Comparative Example 8-2, even when the graphite content is more than 80% by mass, the fracture energy and crack resistance are lowered.
From the above, in silica / silicon carbide / carbon refractories, if the content of the silica raw material is 1 to 50% by mass and the graphite content is 1 to 80% by mass, high bending strength, breaking energy and crack resistance are obtained. It can be seen that property and erosion resistance can be obtained.

A magnesia-carbon refractory having a magnesia raw material content of 85% by mass and a graphite content of 15% by mass (a graphite-containing refractory made of a magnesia raw material as an aggregate) is used as the refractory body x, and FIGS. A tuyere brick (invention example) in which a carbon fiber woven fabric y was bonded via an adhesive cured product a was produced in the form shown in 5. The composition of the carbon fiber woven fabric y, the coefficient of thermal expansion and the coefficient of residual expansion of the refractory body x and the cured adhesive a were the same as in Invention Example 3-2. Further, as a comparative example (conventional example), a tuyere brick having the same structure was produced except that the carbon fiber woven fabric y was not adhered.
These tuyere bricks are installed on the tuyere of the converter, the condition of the tuyere bricks after use is examined, and the wear rate is calculated from the thickness before use, the residual thickness after use, and the number of times the tuyere is used (ch). Calculated. The result is shown in FIG.
No cracks or noticeable melting damage was observed in the tuyere brick of the invention example, and as shown in FIG. 10, the wear rate was reduced by about 40% as compared with the conventional example.

1 Brick component 2 Gas through hole 3 Adhesive material 4 Groove 5 Top surface 6 Bottom surface
x ₀ molded body
a ₀ adhesive
x Refractory body
y carbon fiber woven fabric
a Adhesive cured product
b Adhesive material

Claims (13)

A molding process of molding a refractory raw material having a graphite content of 1 to 80% by mass to obtain a molded body (x ₀ ), and
Adhesion of carbon fiber woven fabric (y) having a mass of 40 to 1300 g per 1 m ^{2 to} at least a part of the surface of the molded body (x ₀ ) obtained in the molding step via an adhesive (a ₀ ). Process and
The bonding step includes a drying step of drying the molded body (x ₀ ) to which the carbon fiber woven fabric (y) is bonded.
A carbon fiber woven fabric (y) is formed on at least a part of the surface of the refractory body (x) composed of the molded body (x ₀ ) via an adhesive cured product (a) composed of the adhesive (a ₀ ). 2. The difference between the coefficient of thermal expansion of the cured adhesive (a) and the coefficient of thermal expansion of the refractory body (x) when the temperature is raised from room temperature to 1000 ° C. Graphite that is 0% or less and the difference between the residual expansion coefficient of the cured adhesive (a) and the residual expansion coefficient of the refractory body (x) when the temperature is lowered from 1000 ° C to room temperature is 2.0% or less. A method for producing a graphite-containing refractory, which comprises obtaining a refractory containing refractory. A molding process of molding a refractory raw material having a graphite content of 1 to 80% by mass to obtain a molded body (x ₀ ), and
A drying step of drying the molded body (x ₀ ) obtained in the molding step, and a drying step.
An adhesive step of adhering a carbon fiber woven fabric (y) having a mass of 40 to 1300 g per m ^{2 to} at least a part of the surface of the molded body (x ₀ ) that has undergone the drying step via an adhesive (a ₀ ). Have and
A carbon fiber woven fabric (y) is formed on at least a part of the surface of the refractory body (x) composed of the molded body (x ₀ ) via an adhesive cured product (a) composed of the adhesive (a ₀ ). 2. The difference between the coefficient of thermal expansion of the cured adhesive (a) and the coefficient of thermal expansion of the refractory body (x) when the temperature is raised from room temperature to 1000 ° C. Graphite that is 0% or less and the difference between the residual expansion coefficient of the cured adhesive (a) and the residual expansion coefficient of the refractory body (x) when the temperature is lowered from 1000 ° C to room temperature is 2.0% or less. A method for producing a graphite-containing refractory, which comprises obtaining a refractory containing refractory. The method for producing a graphite-containing refractory according to claim 1 or 2, further comprising a step of reducing and firing a molded body (x ₀ ) that has undergone a drying step. An adhesive (a ₀ ) of a carbon fiber woven fabric (y) having a weight of 40 to 1300 g per m ² is applied to at least a part of the surface of a molded body (x ₀ ) of a refractory raw material having a graphite content of 1 to 80% by mass. ) Has an bonding process to bond
A carbon fiber woven fabric (y) is formed on at least a part of the surface of the refractory body (x) composed of the molded body (x ₀ ) via an adhesive cured product (a) composed of the adhesive (a ₀ ). 2. The difference between the coefficient of thermal expansion of the cured adhesive (a) and the coefficient of thermal expansion of the refractory body (x) when the temperature is raised from room temperature to 1000 ° C. Graphite that is 0% or less and the difference between the residual expansion coefficient of the cured adhesive (a) and the residual expansion coefficient of the refractory body (x) when the temperature is lowered from 1000 ° C to room temperature is 2.0% or less. A method for producing a graphite-containing refractory, which comprises obtaining a refractory containing refractory. The carbon fiber woven fabric (y) is a woven fabric in which carbon fiber bundles are oriented in two or more directions.
The carbon fiber bundle is a bundle of carbon fibers having a fiber diameter of 1 to 45 μm, and the number of carbon fibers per bundle is more than 100 and 120,000 or less.
The bonding step is characterized in that one or more layers of the carbon fiber woven fabric (y) are bonded to at least a part of the surface of the molded body (x ₀ ) via an adhesive (a ₀ ). The method for producing a graphite-containing refractory according to any one of 1 to 4. The method for producing a graphite-containing refractory according to any one of claims 1 to 5, wherein the adhesive (a ₀ ) is an oxide-based adhesive. The method for producing a graphite-containing refractory according to any one of claims 1 to 6, wherein the refractory raw material contains 20 to 99% by mass of a magnesia raw material having a magnesia concentration of 90% by mass or more. The method for producing a graphite-containing refractory according to any one of claims 1 to 6, wherein the refractory raw material contains 10 to 95% by mass of an alumina raw material having an alumina concentration of 70% by mass or more. The method for producing a graphite-containing refractory according to claim 8, wherein the refractory raw material contains 1% by mass or more of a silicon carbide raw material having a silicon carbide concentration of 80% by mass or more. The method for producing a graphite-containing refractory according to any one of claims 1 to 6, 8 and 9, wherein the refractory raw material contains 1 to 50% by mass of a silica raw material. The method for producing a graphite-containing refractory according to any one of claims 1 to 10, wherein the refractory raw material contains 10 to 90% by mass of refractory waste obtained by crushing a used refractory. A tuyere brick having a gas passage hole (2) penetrating in the longitudinal direction from the upper surface to the bottom surface, which is an operating surface, and a plurality of brick constituent members (1) divided with the longitudinal direction as a dividing surface are bonded layers. It is a method of manufacturing tuyere bricks for refining containers, which is constructed by joining in (b).
Adhesion made of an adhesive (a ₀ ) to at least a part of the surface of a refractory body (x) made of a molded body (x ₀ ) by the manufacturing method according to any one of claims 1 to 11. A brick component (1) to which a carbon fiber woven fabric (y) is bonded via an agent-cured product (a) is manufactured, and the plurality of manufactured brick components (1) are joined with an adhesive material (b). A method for manufacturing tuyere bricks for a refining container, which is characterized by obtaining tuyere bricks. Each brick component (1) to be manufactured has a groove (4) forming a part of a gas passage hole (2) formed on one side surface of a refractory body (x) composed of a molded body (x ₀ ). Then, the carbon fiber woven fabric (y) is adhered to the surface of at least the upper part of the refractory body (x) via the adhesive cured product (a) so as to cover the entire circumference of the refractory body (x). The method for producing a tuyere brick for a refractory container according to claim 12, wherein the tuyere brick is made.

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