JP7100278B2 - Stainless Steel Ladle Magnesia-Spinel-Carbon Brick for Slag Line - Google Patents

Description

The present invention relates to magnesia-spinel-carbon bricks for stainless steel ladle slag lines.

Magnesia-carbon bricks are used in various refining furnaces due to their excellent corrosion resistance and spalling resistance. However, the use of magnesia-carbon bricks in stainless steel ladle can be problematic for carbon pickup into molten steel. Therefore, magnesia-carbon brick with a reduced amount of carbon is generally used for the stainless molten steel ladle slag line. For example, Japanese Patent Application Laid-Open No. 2016-198771 (Patent Document 1) discloses a ladle for stainless molten steel on which MgOC refractory bricks containing 1.5 to 1.9% by mass of C are constructed.

Japanese Unexamined Patent Publication No. 2016-198771

As in the technique of Patent Document 1, it is common to use carbon-reduced magnesia-carbon brick for a stainless molten steel ladle, but when the reduction of carbon causes a problem of deterioration of spalling resistance. was there.

Therefore, it is required to realize a brick that can achieve both suppression of carbon pickup and improvement of polling resistance.

The first stainless molten steel pan slag line magnesia-spinel-carbon brick according to the present invention contains a main material, a binder and an additive, and the main material is 65 to 97 % by mass of a magnesia raw material. , 1 to 30% by mass of spinel raw material, and 2 to 4 % by mass of carbon raw material, and the total content of the binder and the additive is 1 in an external manner with respect to the main material. It is characterized by being about 10% by mass.
The second stainless molten steel pan slag line magnesia-spinel-carbon brick according to the present invention contains a main material, a binder, and an additive, and the main material is 65 to 98% by mass of a magnesia raw material. , 1 to 30% by mass of spinel raw material, and 1 to 5% by mass of carbon raw material, and the total content of the binder and the additive is 1 in addition to the main material. The content of the magnesia raw material in the main material, which passes through a sieve having an opening of 0.3 mm when sifted according to JIS Z 8815: 1994, is 10% by mass or less. And.

According to the first stainless molten steel ladle slag line magnesia-spinel-carbon brick , it is possible to suppress carbon pickup and improve spalling resistance at the same time. Therefore, according to the above configuration, it is possible to provide bricks particularly suitable for stainless steel ladle slag line applications.
According to the second stainless molten steel ladle slag line magnesia-spinel-carbon brick, it is possible to suppress carbon pickup and improve spalling resistance at the same time. Therefore, according to the above configuration, it is possible to provide bricks particularly suitable for stainless steel ladle slag line applications. In addition, since tissue embrittlement due to the reaction between magnesium oxide and carbon is suppressed, the strength of bricks can be improved.

Hereinafter, preferred embodiments of the present invention will be described. However, the scope of the present invention is not limited by the preferred embodiments described below.

The magnesia-spinel-carbon brick for stainless molten steel ladle slag line according to the present invention is, in one embodiment, when the spinel raw material is sieved according to JIS Z 8815: 1994, 80% or more of the total mass has an opening of 1 mm. It is preferable to have a particle size distribution that passes through the sieve.

According to this configuration, the spalling resistance is particularly likely to be improved.

As one aspect of the magnesia-spinel-carbon brick for stainless molten steel ladle slag line according to the present invention, it is preferable that the carbon raw material contains expanded graphite pulverized product.

According to this configuration, good spalling resistance is exhibited while reducing the amount of carbon raw material used. Therefore, it is easy to achieve both improvement of polling resistance and suppression of carbon pickup.

As one aspect of the magnesia-spinel-carbon brick for stainless steel ladle slag line according to the present invention, the binder contains a phenol resin, and the content of the phenol resin is externally applied to the main material. It is preferably 2 to 5% by mass.

According to this configuration, dense and high-strength bricks can be obtained.

The magnesia-spinel-carbon brick for stainless steel ladle slag line according to the present invention is, in one embodiment, the additive being at least one selected from the group consisting of aluminum, silicon, boron carbide, and coal tar pitch. It is preferable to include.

According to this configuration, the strength of the brick is likely to be improved.

Further features and advantages of the invention will be further clarified by the following illustration of exemplary and non-limiting embodiments described with reference to the drawings.

Hereinafter, preferred embodiments of the present invention will be described in detail. It should be noted that the present embodiment described below does not unreasonably limit the content of the present invention described in the claims, and all of the configurations described in the present embodiment are indispensable as the means for solving the present invention. It is not always the case.

[Brick composition]
The magnesia-spinel-carbon brick for stainless steel ladle slag line according to the present embodiment contains a main material, a binder, and an additive. The main material is a component that functions as an aggregate of brick and contains a magnesia raw material, a spinel raw material, and a carbon raw material.

(Magnesia raw material)
In this embodiment, the main material contains 65-98% by mass of magnesia raw material. By setting the content of the magnesia raw material in the main material within the above range, the brick exhibits good corrosion resistance. The content of the magnesia raw material in the main material is more preferably 75% by mass or more. Further, the content of the magnesia raw material in the main material is more preferably 90% by mass or less.

As the magnesia raw material contained in the main material, the magnesia raw material used for conventional magnesia-carbon bricks can be used. Examples of such magnesia raw materials include fused magnesia, seawater magnesia, and natural magnesia. From the viewpoint of corrosion resistance, the magnesia raw material preferably contains magnesium oxide (MgO) in an amount of 97% by mass or more, and more preferably 98% by mass or more.

The particle size distribution of the magnesia raw material contained in the main material may or may not be adjusted according to a conventional method. When the particle size distribution is adjusted, the magnesia raw material is classified into 5-3 mm, 3-1 mm, 1-0.3 mm, and 0.3 mm or less according to, for example, JIS Z 8815: 1994, and a specific class can be increased or decreased. Here, when the content of the magnesia raw material having a particle size of 0.3 mm or less in the main material is 10% by mass or less, tissue embrittlement due to the reaction between magnesium oxide and carbon is suppressed, which is preferable. The main material does not have to contain a magnesia raw material having a particle size of 0.3 mm or less, and the above-mentioned "the content of the magnesia raw material having a particle size of 0.3 mm or less in the main material is 10% by mass or less". It is also possible to use a magnesia raw material that does not contain a magnesia raw material having a particle size of 0.3 mm or less. The content of the magnesia raw material having a particle size of 0.3 mm or less in the main material is more preferably 10% by mass or less, and further preferably 5% by mass or less.

(Spinel raw material)
In the present embodiment, the main material contains 1 to 30% by mass of spinel raw material. By replacing a part of the magnesia raw material constituting the conventional magnesia-carbon brick with a spinel raw material, the spalling resistance is improved as compared with the conventional magnesia-carbon brick. This is because the coefficient of thermal expansion of the spinel raw material is smaller than the coefficient of thermal expansion of the magnesia raw material. However, since the spinel raw material has lower corrosion resistance than the magnesia raw material, if the content of the spinel raw material is excessive, the brick may be easily eroded. The present inventors have diligently studied and found that when the content of the spinel raw material in the main material is 1 to 30% by mass, the balance between spalling resistance and corrosion resistance is good. The content of the spinel raw material in the main material is preferably 10% by mass or more. The content of the spinel raw material in the main material is preferably 20% by mass or less.

The spinel raw material contains magnesium aluminate as a main mineral, and a plurality of types having different ratios of Al ₂ O ₃ and Mg O are commercially available. From the viewpoint of corrosion resistance, the spinel raw material preferably contains 98% by mass or more of magnesium aluminate (Al ₂ O ₃ and MgO), and more preferably 99% by mass or more. The spinel raw material may be either an electrolytic product or a sintered product.

Among the spinel raw materials, those having a ratio of Al ₂ O ₃ and Mg O close to equimolar have a good balance between the coefficient of thermal expansion and corrosion resistance. On the other hand, when Al ₂ O ₃ is excessive, the corrosion resistance may be inferior, and when Mg O is excessive, the coefficient of thermal expansion may be excessive. The spinel raw material preferably has a molar ratio [Al ₂ O ₃ ] / [MgO] of 0.5 to 1.5.

The particle size distribution of the spinel raw material contained in the main material may or may not be adjusted according to a conventional method. If the particle size distribution is adjusted, the spinel feedstock may be classified into 5-3 mm, 3-1 mm, and 1 mm or less according to, for example, JIS Z 8815: 1994, and the specific grade may be increased or decreased. Here, when a spinel raw material having a particle size distribution in which 80% or more of the total mass passes through a sieve having an opening of 1 mm is used, the spalling resistance is particularly likely to be improved. It is more preferable that the spinel raw material has a particle size distribution in which 90% or more of the total mass passes through a sieve having a mesh opening of 1 mm, and 100% of the total mass has a particle size distribution passing through a sieve having a mesh opening of 1 mm. Is more preferable.

The particle size distributions of the magnesia raw material and the spinel raw material contained in the magnesia-spinel-carbon brick for the stainless molten steel ladle slag line can be specified by, for example, the following method. By observing the cut surface of the brick with SEM-EDX (scanning electron microscope / energy dispersive X-ray spectroscopy), the shape and the elements contained therein can be specified for the cross section of the particles exposed on the cut surface. Thereby, for each of the particles exposed on the cut surface, it is possible to identify whether the particles are the magnesia raw material or the spinel raw material. Moreover, since the cross-sectional shape of the particle can be observed, the equivalent sphere diameter of the particle can be calculated. From the above, by observing the cut surface of the brick with SEM-EDX, it is possible to specify the distribution of the particle sizes (corresponding diameters of spheres) of the magnesia raw material and the spinel raw material exposed on the cut surface. By repeating this observation method until a particle size distribution for a statistically significant number of particles is obtained, for each of the magnesia raw materials and spinel raw materials contained in the magnesia-spinel-carbon bricks for stainless steel ladle slag lines. The particle size distribution specified according to JIS Z 8815: 1994 can be specified.

Further, the contents of the magnesia raw material and the spinel raw material in the magnesia-spinel-carbon brick for the stainless molten steel ladle slag line can be specified according to JIS R 2212-4: 2006 or JIS R 2216: 2005.

(Carbon raw material)
In the present embodiment, the main material contains 1 to 5% by mass of carbon raw material. When the content of the carbon raw material in the main material is within the above range, the corrosion resistance and the spalling resistance can be improved as compared with the case where the carbon raw material is not contained, and the carbon pickup is less likely to be a problem. The content of the carbon raw material in the main material is preferably 2% by mass or more. Further, the content of the carbon raw material in the main material is preferably 4% by mass or less.

As the carbon raw material contained in the main material, the carbon raw material used in the conventional magnesia-carbon brick can be used. Examples of such carbon raw materials include scaly graphite, earthy graphite, and pulverized expanded graphite. Of these, when the expanded graphite pulverized product is used, a good effect of improving polling resistance is exhibited with a smaller amount of use as compared with other carbon raw materials. Therefore, it is easy to achieve both improvement of polling resistance and suppression of carbon pickup. Further, from the viewpoint of corrosion resistance, the carbon raw material preferably contains 90% by mass or more of carbon (C), and more preferably 95% by mass or more.

The content of the carbon raw material in the magnesia-spinel-carbon brick for the stainless molten steel ladle slag line can be specified according to JIS R 2011: 2007.

(Binders and additives)
In the magnesia-spinel-carbon brick for stainless steel ladle slag line according to the present embodiment, the total content of the binder and the additive is 1 to 10% by mass in an external manner with respect to the main material. By setting the total content of the binder and the additive in the above range, a dense and strong brick can be obtained. The total content of the binder and the additive is preferably 2% by mass or more, and more preferably 3% by mass or more, based on the main material. Further, the total content of the binder and the additive is preferably 6% by mass or less, more preferably 5% by mass or less, based on the main material.

In the present embodiment, as the binder, a binder used for conventional magnesia-carbon bricks can be used. Examples of such a binder include a novolak-based phenol resin and a resol-based phenol resin. Further, a curing agent such as hexamethylenetetramine may be used in combination. The binder may be one kind of material or a mixture of a plurality of kinds of materials. The content of the binder is preferably 2% by mass or more, more preferably 3% by mass or more, based on the main material. Further, the content of the binder is preferably 6% by mass or less, more preferably 5% by mass or less, based on the main material. When the binder contains a phenol resin, the content of the phenol resin is preferably 2 to 5% by mass with respect to the main material.

In the present embodiment, as the additive, the additive used in the conventional magnesia-carbon brick can be used. Examples of such additives include aluminum, silicon, boron carbide, and coal tar pitch. Of these, aluminum, silicon, and carbon dioxide serve as carbon antioxidants, and coal tar pitch plays a role in closing pores and densifying bricks. The additive may be one kind of material or a mixture of a plurality of kinds of materials. The content of the additive is preferably 3% by mass or less with respect to the main material.

[Brick manufacturing method]
The magnesia-spinel-carbon brick for stainless molten steel pan slag line according to the present embodiment is a compound obtained in a kneading step of kneading a magnesia raw material, a spinel raw material, a carbon raw material, a binder, and an additive, and a kneading step. It can be manufactured through a process including a molding step of molding and a heat treatment step of heat-treating the molded body obtained in the molding step. Further, if necessary, after the heat treatment step, an impregnation step of impregnating the brick with one or more selected from the group consisting of tar and pitch may be provided.

(Kneading process)
For the kneading step, the kneading method in the conventional magnesia-carbon brick manufacturing process can be applied. The magnesia raw material, spinel raw material, carbon raw material, binder, and additive are weighed and kneaded using a kneading device to obtain a compound. The weight ratio of the raw material added in the kneading step may differ from the weight ratio of the raw material contained in the obtained brick because the volatile components in the binder are volatilized in the heat treatment step described later, but it is desired. The weight ratio of the raw materials to be added in order to obtain the goodwill of the composition of the above can be appropriately set by those skilled in the art. As the kneading device, for example, a Connor mixer, a pressurized high-speed mixer equipped with a high-speed stirring blade, an Erich (registered trademark) mixer, or the like can be used.

(Molding process)
For the molding step, the molding method in the conventional magnesia-carbon brick manufacturing process can be applied. The compound obtained in the kneading step is molded using a molding apparatus to obtain a molded product. As the forming apparatus, a general brick forming press apparatus such as a hydraulic press or a friction press can be used. The molding pressure is usually 100 to 250 MPa, more preferably 120 to 220 MPa, still more preferably 140 to 210 MPa, and particularly preferably 150 to 200 MPa. If the molding pressure is less than 100 MPa, molding may be insufficient, and if it exceeds 250 MPa, lamination may occur.

(Heat treatment process)
The heat treatment step is a step for heating the molded product obtained in the molding step to cure the binder and removing volatile components in the binder. The heat treatment referred to here may be referred to as a drying process. The heating temperature in the heat treatment step is preferably 200 ° C. or higher and lower than 300 ° C., more preferably 220 ° C. or higher and lower than 295 ° C., and particularly preferably 230 ° C. or higher and lower than 270 ° C. If the heating temperature is less than 200 ° C, volatile matter may remain in the brick. If the heating temperature is 300 ° C or higher, the binder thermally decomposes and the pores in the brick increase, which causes the pores in the brick to increase. The tissue of the brick itself may loosen and the strength of the brick may decrease.

[Other embodiments]
It should be understood that with respect to other configurations, the embodiments disclosed herein are exemplary in all respects and the scope of the invention is not limited thereto. Those skilled in the art will be able to easily understand that modifications can be made as appropriate without departing from the spirit of the present invention. Therefore, another embodiment modified without departing from the spirit of the present invention is naturally included in the scope of the present invention.

Examples and evaluation methods are shown below, and the effects of the present invention will be described in detail.

[Preparation of sample]
Magnesia raw materials, spinel raw materials, carbon raw materials, binders, and additives were mixed according to the weight ratios shown in the table below, and bricks of Examples and Comparative Examples were prepared according to the production method described in the above-described embodiment. The following materials were used as each raw material.

(Magnesia raw material)
As a magnesia raw material, fused magnesia having an MgO content of 98% by mass was used. The magnesia raw material was classified into 5-3 mm, 3-1 mm, 1-0.3 mm, and 0.3 mm or less according to JIS Z 8815: 1994 and used.

(Spinel raw material)
As a spinel raw material, an fused spinel having an Al ₂ O ₃ content of 75% and an Mg O content of 23% was used. The spinel raw material was classified into 5-3 mm, 3-1 mm, 1-0.3 mm, and 0.3 mm or less according to JIS Z 8815: 1994 and used. Further, the description of "1 mm or less" in the table indicates that the spinel raw materials of the 1-0.3 mm class and the 0.3 mm class are included.

(Scale graphite)
Scale graphite with a carbon (C) purity of 95% was used.

(Expanded graphite crushed product)
An expanded graphite crushed product obtained by crushing a compression-molded graphite sheet after the expansion treatment was used.

(Binders and additives)
Phenol resins, aluminum, silicon, boron carbide, and coal tar pitch were used with the physical characteristics and qualities commonly used in the art.

〔Evaluation method〕
(Spalling resistance)
The spalling resistance was evaluated by a rapid heating and quenching test. For each of the Examples and Comparative Examples, a 40 × 40 × 160 mm test piece was cut out and fired in a reducing atmosphere at 1000 ° C. The test piece was immersed in a hot metal heated to 1680 ° C. for 60 seconds, then immersed in cold water for 15 seconds, and this was repeated twice. The elastic modulus of the test piece was measured before and after the rapid heating and quenching test, and the rate of decrease in the elastic modulus after the test was calculated with respect to the elastic modulus before the test. The elastic modulus was measured in the longitudinal direction of the test piece (direction having a length of 160 mm) by using an ultrasonic propagation method.

Based on the elastic modulus reduction rate, the spalling resistance was evaluated in the following four stages.
AA: The elastic modulus reduction rate is 10% or less.
A: The elastic modulus reduction rate is greater than 10% and 30% or less.
B: The elastic modulus reduction rate is greater than 30% and 70% or less.
C: The elastic modulus reduction rate is larger than 70%.

(Corrosion resistance)
Corrosion resistance was evaluated by the high frequency induction furnace lining method. In the high-frequency induction furnace lining method, each example of the example and the comparative example is lined in the high-frequency induction furnace, and the corrosion resistance is evaluated based on the erosion thickness of the sample measured after melting the steel and the erosion agent in the furnace. How to do it. The test temperature was 1700 ° C., and synthetic slag having a mass ratio (CaO / SiO ₂ ) of 2.8 was used as the erosion agent. The amount of the erosive agent added was 400 g each time, and this was replaced every hour for a total of 6 hours. The sample after the test was cut in the direction perpendicular to the working surface and the maximum melting thickness was measured.

Corrosion resistance was evaluated in the following four stages based on the maximum melting thickness.
AA: The maximum melting thickness is less than 1 mm.
A: The maximum melting thickness is 1 mm or more and less than 2 mm.
B: The maximum melting thickness is 2 mm or more and less than 4 mm.
C: The maximum melting thickness is 4 mm or more.

(Carbon pickup resistance)
The carbon pickup resistance was evaluated by the following method. A high-frequency induction furnace in which each of the examples and comparative examples was constructed as a lining was prepared, and stainless steel was melted at 1700 ° C. in the high-frequency induction furnace. After holding for 1 hour, molten steel was sampled and the carbon content was analyzed. The carbon amount was measured for the test pieces before and after the test, and the rate of increase in the carbon amount after the test was calculated with respect to the carbon amount before the test. The amount of carbon was measured according to JIS G 1213-1: 2018.

Based on the carbon amount increase rate, the carbon pickup resistance was evaluated in the following four stages.
AA: The carbon amount increase rate is 0.008% or less.
A: The carbon amount increase rate is larger than 0.0008% and 0.0010% or less.
B: The carbon amount increase rate is larger than 0.0010% and 0.0013% or less.
C: The rate of increase in carbon content is greater than 0.0013%.

(Porosity)
Porosity was measured according to JIS R 2205: 1992. The smaller the porosity, the better.

(Bending strength)
Bending strength was measured according to JIS R 2213: 2005. The larger the bending strength, the better.

(Oxidation layer thickness)
As an index of oxidation resistance, the thickness of the oxide layer was measured by the following method. A 40 × 40 × 40 mm test piece was set in a resistance electric furnace and treated at 1400 ° C. for 5 hours under the condition of atmospheric atmosphere. Then, the test piece was cut, and the thickness of the oxidized and discolored portion was measured and used as the oxide layer thickness. The smaller the oxide layer thickness, the better the oxidation resistance.

〔Test results〕
The compositions and evaluation results of each example of Examples and Comparative Examples are shown in Tables 1 to 6.

(Composition of main material)
Table 1 shows an example in which the contents of the magnesia raw material and the spinel raw material in the main material are different. Examples 1 to 7 all satisfy the requirements for the contents of the magnesia raw material, the spinel raw material, and the carbon raw material as the magnesia-spinel-carbon brick for the stainless molten steel ladle slag line according to the present invention, and are resistant to spalling. All evaluations of property, corrosion resistance, and carbon pick-up resistance showed a level of B or higher. On the other hand, Comparative Example 1 in which the content of the spinel raw material was excessive (33% by mass) was inferior in corrosion resistance as compared with Examples 1 to 7. Further, Comparative Example 2 containing no spinel raw material was inferior in spalling resistance as compared with Examples 1 to 7.

Table 2 shows an example in which the content of the carbon raw material in the main material is different. Examples 8 to 11 all satisfy the requirements for the contents of the magnesia raw material, the spinel raw material, and the carbon raw material as the magnesia-spinel-carbon brick for the stainless molten steel ladle slag line according to the present invention, and are resistant to spalling. All evaluations of property, corrosion resistance, and carbon pick-up resistance showed a level of B or higher. On the other hand, Comparative Example 3 containing no carbon raw material was inferior in spalling resistance as compared with Examples 8 to 11. Further, Comparative Example 4 in which the content of the carbon raw material was excessive (6% by mass) was inferior in carbon pickup resistance as compared with Examples 8 to 11.

When Table 1 is referred to again and Example 3 and Example 5 are compared, Example 5 using the expanded graphite pulverized product is a carbon raw material as compared with Example 3 using scaly graphite. It can be seen that the content is low, but the spalling resistance is the same. On the other hand, when comparing the carbon pick-up resistance of both, Example 5 in which the content of the carbon raw material is small is better. From the comparison of these examples, it can be seen that it is particularly preferable to use the expanded graphite pulverized product as the carbon raw material.

(Particle size distribution of magnesia raw materials)
Table 3 shows an example in which the particle size distribution of the magnesia raw material is different. In addition, Example 2 is reprinted. All of the examples shown in Table 3 showed a level of A or higher in all evaluations of spalling resistance, corrosion resistance, and carbon pickup resistance, but magnesia raw materials having a small particle size distribution with particles of 0.3 mm or less. In Examples 12 to 14 using the above, particularly good spalling resistance was observed.

(Particle size distribution of spinel raw materials)
Table 4 shows an example in which the particle size distributions of the spinel raw materials are different. In addition, Example 2 is reprinted. All of the examples shown in Table 4 showed a level of B or higher in all evaluations of spalling resistance, corrosion resistance, and carbon pickup resistance, but Example 2 using a spinel raw material classified to 1 mm or less. In and 17, particularly good spalling resistance was observed.

(Phenol resin content)
Table 5 shows an example in which the content of the phenol resin is different. All of Examples 18 to 21 shown in Table 5 showed a level of B or higher in all evaluations of spalling resistance, corrosion resistance, and carbon pickup resistance. In Example 18 in which the content of the phenol resin was 2% by mass with respect to the main material, and Example 19 in which the content of the phenol resin was 6% by mass showed particularly good spalling resistance. On the other hand, in Comparative Example 5 in which the content of the phenol resin was low (0.4% by mass), the binding of the brick was insufficient even after the molding step and the heat treatment step, and a sample to be evaluated could not be obtained. Further, in Comparative Example 6 in which the content of the phenol resin was high (10% by mass), the porosity was high, and the corrosion resistance and the carbon pickup resistance were inferior to those of Examples 18 to 21.

(Content of additive)
Table 6 shows examples in which the substances used as additives and the contents are different. In addition, Example 3 is reprinted. All of the examples shown in Table 6 showed a level of A or higher in all evaluations of spalling resistance, corrosion resistance, and carbon pickup resistance. Examples 22 and 23 containing silicon and boron carbide had a smaller oxide layer thickness than Example 3 not containing them, and showed good oxidation resistance.

The present invention can be used, for example, as brick for a stainless molten steel ladle slag line.

Claims (6)

Contains main materials, binders and additives,
The main material contains 65 to 97 % by mass of magnesia raw material, 1 to 30% by mass of spinel raw material, and 2 to 4 % by mass of carbon raw material.
The total content of the binder and the additive is 1 to 10% by mass on the outside with respect to the main material. Magnesia-spinel-carbon brick for stainless steel ladle slag line. Contains main materials, binders and additives,
The main material contains 65 to 98% by mass of magnesia raw material, 1 to 30% by mass of spinel raw material, and 1 to 5% by mass of carbon raw material.
The total content of the binder and the additive is 1 to 10% by mass in an external manner with respect to the main material.
The stainless molten steel ladle according to claim 1, wherein the content of the magnesia raw material that passes through a sieve having an opening of 0.3 mm when sieved according to JIS Z 8815: 1994 in the main material is 10% by mass or less. Magnesia-spinel-carbon bricks for slag lines. The stainless steel ladle slag line according to claim 1 or 2, wherein the spinel raw material has a particle size distribution in which 80% or more of the total mass passes through a sieve having an opening of 1 mm when sieved according to JIS Z 8815: 1994. For magnesia-spinel-carbon bricks. The carbon raw material is magnesia-spinel-carbon brick for a stainless molten steel ladle slag line according to any one of claims 1 to 3, which contains a pulverized expanded graphite product. The binder contains a phenolic resin and
The magnesia-spinel-carbon brick for stainless steel ladle slag line according to any one of claims 1 to 4, wherein the content of the phenol resin is 2 to 5% by mass in an external manner with respect to the main material. .. The magnesia for a stainless steel ladle slag line according to any one of claims 1 to 5, wherein the additive comprises at least one selected from the group consisting of aluminum, silicon, carbon dioxide, and coal tar pitch. -Spinel-Carbon brick.