JP2021004160A - Brick for hot metal ladle, and hot metal ladle lined with the same - Google Patents

Abstract

To provide a brick for a hot metal ladle, which is excellent in corrosion resistance and has residual expansion properties, and to provide the hot metal ladle lined with the same.SOLUTION: A brick for a hot metal ladle is obtained by adding an organic binder to a refractory raw material compound, mixing them, molding the resultant mixture, and then heating the molded mixture. The refractory raw material compound comprises: 5 mass% or more and 20 mass% or less of a silica having a particle size of 1 mm or more and less than 5 mm; 45 mass% or more and 80 mass% or less of an alumina-based raw material; 5 mass% or more and 20 mass% or less of graphite; and 0.3 mass% or more and 4 mass% or less of aluminum and/or aluminum alloy, wherein a content ratio of silicon carbide is 20 mass% or less (including 0), a content ratio of pyrophyllite having a particle size of 1 mm or more and less than 5 mm is 10 mass% or less (including 0), and when the brick comprises the pyrophyllite having the particle size of 1 mm or more and less than 5 mm, the total of the content ratio of pyrophyllite and a content ratio of silica having the particle size of 1 mm or more and less than 5 mm is 20 mass% or less. The brick is lined to the hot metal ladle.SELECTED DRAWING: None

Description

The present invention relates to a brick for a hot metal pot used as a lining material for a hot metal pot for transporting hot metal, and a hot metal pot lined with the brick.

As the lining material for hot metal pots, volume stability that responds to thermal shock caused by heating and cooling is particularly important, so joint openings during cooling are avoided based on alumina, silicon carbide, and carbon refractories. Therefore, a residual expandable raw material for imparting residual expandability is added. This is because if joint opening occurs during cooling, hot metal intrusion is likely to occur during operation.

For example, Patent Document 1 states, "Highly thermally expandable and highly residual expandable silica or silica-alumina raw material 20 to 80% by weight, alumina raw material 20 to 77% by weight containing 80% by weight or more of grains having a particle size of 80 μm or more. , A non-firing refractory for hot metal containers, which comprises a carbon material or a carbon material, 3 to 30% by mass of silicon carbide, and a resin-based binder "(see the scope of patent claims). Further, according to Patent Document 1, "The SiO ₂ component in silica or silica / alumina raw material is transformed from α-quartz to β-quartz and cristobalite by heating, and high thermal expansion due to broaching at a higher temperature. High residual swelling prevents the opening of brick joints "(see lines 12 to 16 in the lower left column on page 2). Then, in the example of Patent Document 1, 20% by mass of pyrophyllite as a silica-alumina raw material having a particle size of 65 μm or more and 85% or more is contained in 100% by mass of the fireproof raw material mixture (Example in Table 1). 1) and an example in which 25% by mass of silica stone is contained as silica having a particle size of 65 μm or more and 85% or more (Example 3 in Table 1) are disclosed.
However, pyrophyllite is mainly pyrophyllite and also contains sub-constituent minerals such as quartz, kaolinite, and seisite. Quartz among these gives residual expansion to bricks as described above, but pyrophyllite When it is contained in an amount of 20% by mass, there is a problem that the corrosion resistance is lowered because the amount of liquid phase formed in the brick is increased due to the pyrophyllite and the alkaline component in the pyrophyllite and the impurities in other raw materials.
On the other hand, when silica stone is contained in an amount of 25% by mass, an increase in the silica component is directly linked to a decrease in slag erosion resistance, resulting in a decrease in life. Furthermore, sintering is promoted by increasing the liquid phase generated by the reaction of the alumina aggregate in the brick, the silica component, and other low-melting components (iron oxide, alkali, etc.), resulting in densification and plastic deformation of the brick. .. As a result, deterioration on the working surface side due to long-term use and densification due to the progress of sintering progress, and in the final stage, cracking and peeling, and invasion of hot metal into the joint due to joint opening surface, resulting in durability instability. It will be.

Japanese Unexamined Patent Publication No. 2-22167

An object to be solved by the present invention is to provide a brick for a hot metal pot having excellent corrosion resistance and residual expandability, and a hot metal pot lined with the brick.

The present inventors use silica stone having a particle size of 1 mm or more and less than 5 mm in a fire-resistant raw material formulation in an amount of 5% by mass or more and 20% by mass or less in a brick for a hot pot mainly composed of alumina and graphite to provide corrosion resistance and residual expansion. It was found that bricks for hot metal pots with excellent properties can be obtained.

That is, according to the present invention, the bricks for hot metal pots according to the following 1 to 4 and the hot metal pots lined with the bricks are provided.
1. 1.
Brick for hot metal pots obtained by adding an organic binder to a fire-resistant raw material compound, kneading, molding, and then heat-treating.
The fire-resistant raw material formulation includes 5% by mass or more and 20% by mass or less of silicate having a particle size of 1 mm or more and less than 5 mm, 45% by mass or more and 80% by mass or less of an alumina raw material, 5% by mass or more and 20% by mass or less of graphite, aluminum and /. Alternatively, the content of aluminum alloy is 0.3% by mass or more and 4% by mass or less, the content of silicon carbide is 20% by mass or less (including 0), and the content of brazingite having a particle size of 1 mm or more and less than 5 mm is 10% by mass or less. (Including 0)
In addition, when pyrophyllite having a particle size of 1 mm or more and less than 5 mm is contained, the total content of silica stone having a particle size of 1 mm or more and less than 5 mm is 20% by mass or less.
2. 2.
The brick for hot metal pot according to 1 above, wherein the alumina raw material is one or more selected from banquet, bauxite, mullite, sintered alumina, and fused alumina.
3. 3.
Furthermore, it is characterized in that one or more of silicon, boron carbide, glass powder, magnesia, carbon black, and pitch powder are contained in a total amount of 5% by mass or less as a ratio in 100% by mass of the fireproof raw material compound. The hot metal pot brick according to 1 or 2 above.
4.
A hot metal pan lined with the brick for hot metal pan according to any one of 1 to 3 above.

The particle size referred to in the present invention is the size of the sieve mesh when the fireproof raw material particles are sieved and separated. For example, a silica stone having a particle size of 1 mm or more has a sieve mesh of 1 mm. A silica stone that does not pass through, and a silica stone having a particle size of less than 5 mm is a silica stone that passes through a sieve having a sieve mesh of 5 mm.

According to the present invention, by using a specific amount of silica stone having a particle size of 1 mm or more and less than 5 mm in the fire-resistant raw material compound, it is possible to obtain sufficient residual expansion while suppressing a decrease in corrosion resistance. As a result, the life of the hot metal pot can be significantly improved.

In the hot metal pot brick of the present invention, first, the refractory raw material compound contains 5% by mass or more and 20% by mass or less of silica stone having a particle size of 1 mm or more and less than 5 mm, 45% by mass or more and 80% by mass or less of an alumina raw material, and graphite. 5% by mass or more and 20% by mass or less, aluminum and / or aluminum alloy in 0.3% by mass or more and 4% by mass or less, and silicon carbide in 20% by mass or less (including 0) are used.

As described above, silica stone having a particle size of 1 mm or more and less than 5 mm is used for the fireproof raw material compound of the present invention. In bricks mainly composed of alumina and graphite, when silica stone is contained, the amount of silica increases, so that there is a problem that the slag resistance is lowered. However, the larger the particle size of the silica stone, the more the deterioration of the slag resistance can be suppressed.
Further, the brick for hot metal pot of the present invention contains graphite in the matrix portion, and the expansion of fine silica stone having a particle size of less than 1 mm is partially absorbed by this matrix portion, so that the brick as a whole has sufficient residual expansion. The effect will not be obtained. On the other hand, coarse-grained silica stone with a particle size of 1 mm or more has many parts in contact with the coarse-grained silica stone and the coarse-grained alumina-based raw material, and the distance between the coarse-grained silica stones is short, so that the expansion of the silica stone is graphite. The entire brick can be expanded with almost no absorption by the matrix portion with a large amount of silica.

From the above viewpoint, silica stone having a particle size of 1 mm or more is used in the fireproof raw material compound of the present invention. If the particle size of the silica stone becomes too large, the filling property of the clay during molding deteriorates. Therefore, the particle size of the silica stone used in the fireproof raw material compound of the present invention is set to 1 mm or more and less than 5 mm.
However, silica stone having a particle size of less than 1 mm is acceptable as long as it is 20% by mass or less when the total amount of silica stone with a particle size of 1 mm or more and less than 5 mm is 100% by mass, because there is no significant effect. Further, a small amount of silica stone having a particle size of 5 mm or more is acceptable, and can be, for example, 5% by mass or less.
When the content of silica stone having a particle size of 1 mm or more and less than 5 mm is less than 5% by mass in the proportion of 100% by mass of the fire-resistant raw material compound, the effect of residual expansion becomes insufficient, and when it exceeds 20% by mass, the corrosion resistance is lowered.

As the silica stone, it is usually used as a raw material for refractories such as silica stone bricks, and naturally mined raw materials can be used, and those having a SiO ₂ content of 95% by mass or more are preferably used. be able to. In addition, SiO ₂ is contained as quartz in silica stone.

The alumina-based raw material is used because it has excellent corrosion resistance against slag in hot metal. Specifically, it is used at a content of 45% by mass or more and 80% by mass in the proportion of 100% by mass of the fire-resistant raw material mixture. If the content is less than 45% by mass, the corrosion resistance becomes insufficient, and if it exceeds 80% by mass, the thermal shock resistance is lowered.
As the alumina raw material, one or more selected from banquet, bauxite, mullite, sintered alumina, and fused alumina can be preferably used. Specifically, banquets have an Al ₂ O ₃ content of 80% by mass or more, bauxite has an Al ₂ O ₃ content of 85% by mass or more, and mulite has an Al ₂ O ₃ content of 65% by mass. % Or more, sintered alumina having an Al ₂ O ₃ content of 95% by mass or more, and fused alumina having an Al ₂ O ₃ content of 95% by mass or more are preferably used. Can be done.
These alumina raw materials can be selected according to the operating conditions of the hot metal pot to be used, and can be used alone or in combination of a plurality of alumina raw materials. Further, when banquets or bauxite having more impurities than sintered alumina or fused alumina are used, deterioration of corrosion resistance can be suppressed by reducing the amount of silica stone or pyrophyllite used.
The alumina raw material can be used in the entire particle size range from fine particles (particle size less than 1 mm) to coarse particles (particle size 1 mm or more).

Graphite is used to ensure heat impact resistance, and specifically, it is used at a content of 5% by mass or more and 20% by mass or less in a proportion of 100% by mass of the fireproof raw material compound. If the content is less than 5% by mass, the thermal shock resistance becomes insufficient, and if it exceeds 20% by mass, the strength development during operation is suppressed, internal cracks occur, wear resistance is lowered, and the heat of bricks is reduced. Conductivity increases and the hot metal temperature drops.
As the graphite, those usually used as a raw material for refractories such as scaly graphite can be used, and those having a particle size of less than 0.5 mm can be preferably used.

Aluminum and / or aluminum alloy is used for antioxidant and strength imparting, and specifically, it is used at a content of 0.3% by mass or more and 4% by mass in the proportion of 100% by mass of the fireproof raw material compound. If the content is less than 0.3% by mass, the effects of antioxidant and strength imparting cannot be sufficiently obtained, and if it exceeds 4% by mass, the thermal shock resistance is lowered due to the excessive sintering effect, and cracks and peeling occur. Concerns grow.
As these aluminum, aluminum alloy, and other metals such as silicon described later, those usually used as raw materials for refractories can be used, and those having a particle size of less than 0.1 mm can be preferably used. it can. Examples of the aluminum alloy include an aluminum magnesium alloy and an aluminum silicon alloy.

On the other hand, since pyrophyllite contains quartz, residual expansion can be obtained by using it, but its effect is smaller than that of silica stone, so basically it is not necessary to use it. However, when silica stone is used alone, rapid expansion may occur at around 600 ° C and around 1300 ° C, and in order to avoid cracks due to rapid expansion, pyrophyllite is used in combination with silica stone to adjust to gentle expansion. It becomes possible to do. Therefore, depending on the operating conditions of the hot metal pot, pyrophyllite having a particle size of 1 mm or more and less than 5 mm can be contained (used) in an amount of 10% by mass or less in 100% by mass of the fireproof raw material mixture. However, when pyrophyllite having a particle size of 1 mm or more and less than 5 mm is contained (used), the total amount with silica stone having a particle size of 1 mm or more and less than 5 mm is 20% by mass or less.
As the pyrophyllite, those usually used as a raw material for refractories can be used, and those having a particle size of 1 mm or more and less than 5 mm can be preferably used as in the case of silica stone. Although some pyrophyllite is heat-treated, the present invention uses one that is not heat-treated.

Since aluminum and / or an aluminum alloy is used in the fire-resistant raw material compound of the present invention, it has an antioxidant effect, but when it is desired to further enhance the antioxidant effect or when it is desired to enhance the thermal shock resistance. Can be used at a content of 20% by mass or less in proportion to 100% by mass of the fireproof raw material compound. If the content exceeds 20% by mass, excessive sintering near the operating surface is likely to occur, raising concerns about structural spalling, and the effect of silica decomposed and generated by the reaction in the CO atmosphere during operation. There is also concern about a decrease in corrosion resistance.
As the silicon carbide, one having a SiC content of 85% by mass or more and a particle size of less than 0.3 mm can be preferably used.

In addition, in the refractory raw material compound of the present invention, metals other than aluminum or aluminum alloy (for example, silicon), boron carbide, glass powder, magnesia, carbon black and pitch are used as refractory raw materials commonly used for refractory materials other than the above. One or more of the powders can be used in a proportion of 100% by mass of the refractory raw material mixture, and the total amount can be 5% by mass or less.

The brick for hot metal pot of the present invention can be obtained by adding an organic binder such as phenol resin to the above-mentioned fire-resistant raw material compound, kneading it, and heat-treating it after molding. Here, the organic binder is used for known purposes such as to obtain strength after molding and heat treatment, and further to form a carbon bond by receiving heat during use, and is used in general non-fired bricks. A known organic binder can be added at the time of kneading in a general ratio according to the production conditions. Specifically, it can be in the range of 1% by mass or more and 5% by mass or less by externally covering 100% by mass of the fireproof raw material compound. Similarly, the heat treatment temperature can be adopted without any problem as long as it is within the range of the known heat treatment temperature for non-fired bricks using a normal organic binder. Specifically, the temperature can be 160 ° C. or higher and 800 ° C. or lower.
Then, by lining this brick for hot metal pot, the hot metal pot of the present invention can be obtained.

To each of the fire-resistant raw material formulations shown in Tables 1 and 2, phenol resin as an organic binder was added in an external amount of 3% by mass with respect to 100 mass of the fire-resistant raw material compound, and after kneading, 230 × 114 × 100 mm was added by a friction press. Brick was formed into a goodwill shape and heat-treated at 250 ° C. to obtain goodwill of each Example and each Comparative Example.
In Tables 1 and 2, fused alumina and sintered alumina have an Al ₂ O ₃ content of 97% by mass, banquets have an Al ₂ O ₃ content of 82% by mass, and bauxite has an Al ₂ O ₃ content. 87% by mass, the fused light used had an Al ₂ O ₃ content of 66% by mass, and the bauxite used had a SiO ₂ content of 97% by mass. Further, as the pyrophyllite, a low alkaline pyrophyllite having an Al ₂ O ₃ content of 17% by mass was used, and as the silicon carbide, one having a SiC content of 90% by mass was used. Furthermore, scaly graphite uses 85% by mass of fixed carbon, borosilicate glass as the glass powder, magnesia uses fused magnesia with an MgO content of 95% by mass, and the pitch uses a softening point of 230 degrees. did.

With respect to the obtained brick, the apparent porosity, compressive strength, and residual expansion coefficient were measured, and the corrosion resistance and thermal shock resistance were evaluated.
The apparent porosity was measured in accordance with JIS R 2205 using a prismatic sample having a size of 50 × 50 × 50 mm and using white kerosene as a solvent. The compressive strength was measured according to JIS R 2206 using a prismatic sample of 50 × 50 × 50 mm.
The residual expansion rate was measured from the change in the height of the sample before and after the heat treatment held at 1400 ° C. for 3 hours under a load of 0.2 MPa using a cylindrical sample having a diameter of 50 mm and a height of 50 mm.
Corrosion resistance uses a trapezoidal brick-shaped sample of upper base 45 x lower base 105 x height 60 x length 120 mm, and erosion is repeated 5 times at 1500 ° C for 1 hour by the rotary slag erosion test method, and the sample centerline before and after the test. The amount of erosion (mm) was determined from the difference in thickness (mm). Pig iron and blast furnace slag with C / S = 1.1 were used as erosion agents. In Tables 1 and 2, the corrosion resistance is expressed as an index with the erosion amount (mm) of Comparative Example 4 as 100. The smaller this index is, the better the corrosion resistance is.
In the evaluation of thermal shock resistance, a sample having a size of 40 × 40 × 190 mm is reduced and fired at 1400 ° C. × 3 hours, immersed in hot metal at 1500 ° C. for 90 seconds, and then water-cooled for 30 seconds is repeated 10 times. A test was conducted and the state of cracks and peeling was observed. In the table, "excellent" means that there was no crack or peeling after the test, "good" means that there was a slight crack or peeling, "OK" means that there was a moderate crack or peeling, and "impossible". Is a large crack / peeling.
As for the overall pass / fail, those with a residual expansion coefficient of 1.20% or more, a corrosion resistance index of 100 or less, and a thermal shock resistance of "excellent", "good" or "acceptable" are passed, and the residual expansion rate is Those with less than 1.20%, a corrosion resistance index of more than 100, or a thermal shock resistance of "impossible" were rejected.

It should be noted that the apparent porosity and the compressive strength are one of the basic physical properties of bricks, and it is well known to those skilled in the art that they affect the corrosion resistance and thermal shock resistance of bricks. Measured as information.

In Table 1, Examples 1 to 5 have different contents of silica stone having a particle size of 1 mm or more and 5 mm, but all of them are within the range of the present invention and are excellent in residual expansion coefficient and corrosion resistance. The silica stone used in Example 4 is 20% by mass when the ratio of the particle size of less than 1 mm to the silica stone having a particle size of 1 mm or more and less than 5 mm is 100% by mass.

On the other hand, in Comparative Example 1, the content of silica stone having a particle size of 1 mm or more and less than 5 mm was 2% by mass, which was lower than the lower limit of the present invention, resulting in insufficient residual expansion coefficient. Further, in Comparative Example 2, the content of silica stone having a particle size of 1 mm or more and less than 5 mm was 25% by mass, which exceeded the upper limit of the present invention, resulting in inferior corrosion resistance.
In Comparative Example 3, 15% by mass of silica stone having a particle size of less than 1 mm was used, but the residual expansion coefficient was smaller and the corrosion resistance was inferior as compared with Example 3.
In Comparative Example 4, a pyrophyllite having a particle size of 1 mm or more and less than 5 mm was used instead of silica stone, but the result was that the residual expansion coefficient was insufficient.
Comparative Example 5 contains 4% by mass of pyrophyllite, but 3% by mass of silica stone, which is below the lower limit of the present invention, and the residual expansion is insufficient.
In Comparative Example 6, the content of the alumina raw material was 37% by mass, which was lower than the lower limit of the present invention, resulting in inferior corrosion resistance. In Comparative Example 7, the content of the alumina raw material was 85% by mass, which was the upper limit of the present invention. The result was that the value was exceeded and the thermal shock resistance was inferior.

In Table 2, in Examples 6 to 9, sintered alumina, banquet, bauxite, and fused mullite are used instead of the fused alumina, and silica stone having a particle size of 1 mm or more and less than 5 mm and a particle size of 1 mm or more and less than 5 mm are used. Although it was used in combination with pyrophyllite and aluminum and silicon, the results were excellent in residual expansion rate and corrosion resistance.

Example 10 uses a combination of fused alumina and a banquet, Example 11 uses an aluminum magnesium alloy, boron carbide, pitch powder, glass, magnesia, and carbon black, and Examples 12 and 13 use. The aluminum content was changed, Example 14 was a combination of aluminum and an aluminum magnesium alloy, and Example 15 was an increase in the silicon carbide content to 20% by mass, all of which are of the present invention. The result was within the range and excellent in residual expansion rate and corrosion resistance.

On the other hand, in Comparative Example 8, the total of silica stone having a particle size of 1 mm or more and less than 5 mm and pyrophyllite having a particle size of 1 mm or more and less than 5 mm was 25% by mass, which is outside the scope of the present invention. It was 15% by mass, which was outside the range of the present invention, and the result was that the corrosion resistance was inferior in each case.

Further, in Comparative Example 10, since aluminum and an aluminum alloy were not used, the oxidation resistance was lowered, and as a result, the corrosion resistance was lowered. In Comparative Example 11, the aluminum content was 5% by mass, which exceeded the upper limit of the present invention. Thermal impact resistance has decreased.

In Comparative Example 12, the content of silicon carbide was 25% by mass, which exceeded the upper limit of the present invention, resulting in inferior corrosion resistance.

In Comparative Example 13, the graphite content was lower than the lower limit of the present invention, so that the thermal shock resistance was lowered, and in Comparative Example 14, the graphite content was higher than the upper limit of the present invention, so that the corrosion resistance was lowered.

When the bricks of Example 3 and Comparative Example 4 were lined on the side wall of the hot metal pot and used, the side wall lined with the brick of Example 3 had a longer life than that of the side wall lined with the brick of Comparative Example 4. It was confirmed that it was 1.4 times larger.

Claims (4)

Brick for hot metal pots obtained by adding an organic binder to a fire-resistant raw material compound, kneading, molding, and then heat-treating.
The fire-resistant raw material formulation includes 5% by mass or more and 20% by mass or less of silicate having a particle size of 1 mm or more and less than 5 mm, 45% by mass or more and 80% by mass or less of an alumina raw material, 5% by mass or more and 20% by mass or less of graphite, aluminum and /. Alternatively, the content of aluminum alloy is 0.3% by mass or more and 4% by mass or less, the content of silicon carbide is 20% by mass or less (including 0), and the content of brazingite having a particle size of 1 mm or more and less than 5 mm is 10% by mass or less. (Including 0)
In addition, when pyrophyllite having a particle size of 1 mm or more and less than 5 mm is contained, the total content of silica stone having a particle size of 1 mm or more and less than 5 mm is 20% by mass or less. The brick for hot metal pot according to claim 1, wherein the alumina-based raw material is one or more selected from banquet, bauxite, mullite, sintered alumina, and fused alumina. Further, it is characterized in that one or more of silicon, boron carbide, glass powder, magnesia, carbon black, and pitch powder are contained in a total amount of 5% by mass or less as a ratio in 100% by mass of the fireproof raw material mixture. The brick for hot metal pot according to claim 1 or 2. A hot metal pan lined with the brick for hot metal pan according to any one of claims 1 to 3.