JP7219980B2 - Hot injection repair material and hot spray repair material - Google Patents

Description

The present invention relates to a hot injection repair material and a hot spray repair material used for hot repair of electric furnaces for ironmaking, hot metal or molten steel containers for holding molten iron or molten steel (hot metal ladle, molten steel ladle, tundish, etc.). . In this specification, the hot injection repair material and the hot spray repair material are collectively referred to as "hot repair material".

For example, a general lining structure for steelmaking electric furnaces is a structure in which the surface of lining bricks is covered with a refractory stamped material. The top of the lining corresponds to the slag line and is pre-worn. The slag line is usually provided with magnesia-carbon bricks that are highly resistant to slag erosion. However, the service life of the slug line is still not sufficient and is still subject to premature wear. Therefore, the slag line is repaired by hot spraying as needed in anticipation of wear. In addition, hot charging repair is performed for repairing the bottom of the furnace.

Magnesia is known as a material for hot repair materials used in such hot repairs (for example, Patent Documents 1 and 2). Magnesia is a highly corrosion resistant material. However, conventional hot repair materials tend to peel off from repaired parts (slag lines, furnace bottoms, etc.) when restarting after hot repair, and as a result, sufficient repair effects have not been obtained.

Japanese Patent No. 6735064 JP 2012-126610 A

The problem to be solved by the present invention is to provide a hot repair material having a high repair effect.

The present inventors noted that high-temperature slag remains on the surface of the portion to be repaired during hot repair. Considering that it is important to improve the hot affinity adhesion with the slag that is present, we conducted repeated tests and studies. As a result, it was found that it is effective to mix the matrix portion of the hot repair material (fine powder refractory material with a particle size of less than 1 mm) so as to generate secondary spinel during hot repair. The inventors have found that it is effective to use used alumina shots that have been used in shot blasting to remove scales on the inner surface of steel pipes as an alumina source for producing alumina shots, and have completed the present invention. .

That is, according to one aspect of the present invention, the following hot injection repair material is provided.
Used alumina shot (hereinafter referred to as "used alumina shot") used in shot blasting for removing scales on the inner surface of steel pipes, in proportion to 100% by mass of the refractory material, and having a particle size of less than 1 mm contains 55 to 85% by mass of used alumina shot fine powder and 15 to 45% by mass of magnesia fine powder having a particle size of less than 1 mm, and the mass ratio of used alumina shot fine powder to magnesia fine powder (used alumina shot fine powder: magnesia fine powder) in the range of 55:45 to 85:15.

Further, according to another aspect of the present invention, the following hot spray repair material is provided.
The refractory material includes a coarse refractory material with a particle size of 1 mm or more and a fine refractory material with a particle size of less than 1 mm, and the mass ratio of the coarse refractory material to the fine refractory material (coarse refractory material A hot spray repair material in which the material: fine powder refractory material) is in the range of 30:70 to 55:45,
The coarse-grained refractory material is a basic refractory material,
The fine powder refractory material is used alumina shot (hereinafter referred to as "used alumina shot") used in shot blasting for removing the inner surface scale of the steel pipe, in a proportion of 100% by mass of the fine powder refractory material. ), containing 55 to 85% by mass of used alumina shot fine powder having a particle size of less than 1 mm and 15 to 45% by mass of magnesia fine powder having a particle size of less than 1 mm, and a mixture of used alumina shot fine powder and magnesia fine powder A hot spray repair material having a mass ratio (alumina shot fine powder after use:magnesia fine powder) in the range of 55:45 to 85:15.

According to the hot repair material of the present invention, the hot affinity adhesion with the slag remaining on the surface of the portion to be repaired is improved during hot repair. Therefore, it becomes difficult to separate from the part to be repaired, and a high repair effect can be obtained.

Explanatory drawing which shows notionally the effect of the hot injection|throwing-in repair material of this invention. FIG. 2 is an explanatory diagram conceptually showing the effects of the hot spray repair material of the present invention. A stereoscopic microscope observation photograph (×200) of alumina shot fine powder after use. SEM observation photograph (×100) of alumina shot fine powder (magnetically separated) after use. SEM observation photograph of alumina shot before use (x 100). Table 2 shows the test results of evaluating hot affinity adhesion with slag for the hot injection repair materials of Examples 1 to 3 and Comparative Example 1 (slag basicity (C/S) = 0.55). Table 2 shows the test results of evaluating hot affinity adhesion with slag for the hot injection repair materials of Examples 1 to 3 and Comparative Example 1 (slag basicity (C/S) = 1.74). Cross-sectional SEM observation photographs of the test piece after heat treatment of Example 2 shown in Table 2 (when slag basicity (C / S) = 0.55), (a) and (b) are hot input A cross-sectional SEM observation photograph of the body portion of the repair material, (c) is a cross-sectional SEM observation photograph of the interface portion with the magnesia brick. Table 3 shows the test results of the hot injection repair materials of Example 2 and Comparative Example 2 that evaluated the hot affinity adhesion with slag (slag basicity (C/S) = 1.74). Test results of the hot spray repair materials of Example 4 and Comparative Example 3 shown in Table 4, evaluating the hot affinity adhesion to slag. The slag corrosion test results for the hot spray repair materials of Example 4 and Comparative Examples 4 and 5 shown in Table 5 (slag basicity (C/S) = 1). The slag corrosion test results for the hot spray repair materials of Example 4 and Comparative Examples 4 and 5 shown in Table 5 (slag basicity (C/S) = 3).

The hot injection repair material, which is one aspect of the present invention, contains 55 to 85% by mass of used alumina shot fine powder and 15 to 45% by mass of magnesia fine powder in terms of the ratio of 100% by mass of refractory material, and used alumina The mass ratio of shot fine powder to magnesia fine powder (used alumina shot fine powder:magnesia fine powder) (hereinafter referred to as "alumina-magnesia mass ratio") is in the range of 55:45 to 85:15.

By setting the alumina-magnesia mass ratio to the above range, a secondary spinel is generated during hot injection repair, thereby improving hot affinity adhesion with slag remaining on the surface of the repaired part during hot injection repair. improves. In addition, the hot compactness is improved due to the volume expansion associated with the formation of the secondary spinel. The theoretical spinel has an alumina-magnesia mass ratio of approximately 70:30, but the test results described later confirm that the above-mentioned effects can be obtained if the alumina-magnesia mass ratio is in the range of 55:45 to 85:15. there is

The post-use alumina shot fine powder contains scales on the inner surface of steel pipes (hereinafter simply referred to as "scales") that have been removed by shot blasting. This scale acts as a sintering aid, further improving hot affinity adhesion with slag and hot compactness. In addition, the alumina shot fine powder after use has a rounded shape with chipped corners. For this reason, the fluidity at the time of injection construction is improved, and the fillability to the repaired part is also improved. It should be noted that the material of the alumina shot fine powder after use is preferably brown alumina, not white alumina, from the viewpoint of hardness and cost required for shot blasting.

As described above, according to the hot injection repair material of the present invention, as conceptually shown in FIG. Improves interstitial density. In particular, the hot charging affinity with slag is a characteristic that was not considered in conventional hot charging repair materials, and the hot charging of the present invention improves the hot charging affinity with slag. This is the greatest feature of the repair material. As a result, the hot injection repair material is less likely to separate from the portion to be repaired, and a high repair effect can be obtained.

The hot injection repair material is put in a heat-dissipable bag such as a flexible container bag and put into the repaired part, and is sometimes called a "seizure repair material". The hot injection repair material of the present invention, like the conventional baking repair material, is obtained by adding an inorganic binder such as sodium silicate or an organic binder such as resin, sugar, pitch, or tar to the above-described refractory material. can also be

In the hot-spray repair material, which is another embodiment of the present invention, the composition of the matrix portion made of fine refractory material having a particle size of less than 1 mm is the same as that of the above-described hot injection repair material. That is, in the hot spray repair material of the present invention, the matrix portion (fine powder refractory material) contains 55 to 85% by mass of alumina shot fine powder after use in the ratio of 100% by mass of the matrix portion (fine powder refractory material). , containing 15 to 45% by mass of magnesia fine powder, and having an alumina-magnesia mass ratio in the range of 55:45 to 85:15.

Therefore, the hot spray repair material of the present invention also has improved hot affinity adhesion to slag and hot compactness. In addition, since the alumina shot fine powder after use has a rounded shape, the stability of spraying is also improved.

On the other hand, the hot spray repair material of the present invention contains a coarse-grained refractory material having a grain size of 1 mm or more as an aggregate portion of the refractory material. The mass ratio (coarse-grained refractory material: fine-grained refractory material) of the aggregate portion (coarse-grained refractory material) and the matrix portion (fine-grained refractory material) (hereinafter referred to as the “coarse-grained refractory material mass ratio”) has been conventionally It is within the range of 30:70 to 55:45, as with general hot spray repair materials.

Hot spray repair materials are often used to repair slag lines. Since the slag line is required to have slag erosion resistance, the coarse-grained refractory material that is the aggregate portion in the hot spray repair material of the present invention is made of a basic refractory material. This is because the basic refractory material is excellent in slag corrosion resistance. Examples of the basic refractory material include magnesia, calcined olivine, calcined dolomite, and used magnesia-carbon brick waste. The coarse-grained refractory material preferably contains magnesia in terms of increasing slag erosion resistance. As magnesia, natural magnesia, calcined magnesia, electro-fused magnesia, and seawater magnesia can be used. Also, the maximum grain size (top size) of the aggregate portion is preferably 2 mm or more and less than 5 mm, as in the conventional technology. In addition, the particle size of the refractory material can be adjusted with a sieve. In the present invention, a particle size of 1 mm or more corresponds to a sieve with an opening of 1 mm. Conversely, the particle size of less than 1 mm means the size under a sieve with an opening of 1 mm.

Further, in the hot spray repair material of the present invention, the matrix portion has high hot affinity adhesion to slag as described above, and thus has the effect of increasing the viscosity of slag. This effect of increasing the viscosity of slag contributes to the improvement of resistance to chemical erosion by slag, that is, slag erosion resistance. That is, according to the hot spray repair material of the present invention, in addition to the aggregate portion being a basic refractory material with excellent slag erosion resistance, the matrix portion has the effect of increasing the viscosity of the slag. An effect of improving slag corrosion resistance can be obtained.

The slag line is not only chemically eroded by slag, but also mechanically affected by slag flow. When subjected to such mechanical action, the hot spray repair material applied to the slag line is likely to separate from the slag line. On the other hand, according to the hot spray repair material of the present invention, as described above, the hot affinity adhesion with the slag remaining on the surface of the slag line during hot spray repair is high. It is difficult to peel off from the slag line even if it is subjected to mechanical action such as.

As described above, according to the hot spray repair material of the present invention, as conceptually shown in FIG. The hot affinity adhesion with the slag remaining in the steel is improved, and the hot compactness is also improved. In addition, even on the operating surface that comes into contact with slag when restarting operation after hot spray repair, the hot affinity adhesion with slag is improved and the effect of increasing the viscosity of slag is achieved, so slag erosion resistance is improved.
As described above, according to the hot spray repair material of the present invention, it is possible to obtain a higher repair effect than the conventional hot spray repair material.

The hot spray repair material of the present invention can be applied not only to the slag line but also to the steel bath below the slag line. Also in this case, the hot spray repair material of the present invention has a high hot affinity adhesion with the slag remaining on the surface of the steel bath during hot spray repair, so that the mechanical strength caused by the flow of molten steel, etc. It becomes difficult to peel off from the steel bath even if it receives a strong action, and a high repair effect can be obtained.

The hot spray repair material of the present invention, like the conventional hot spray repair material, is obtained by adding a binder to the above-described refractory material. The binder is not particularly limited. Phosphates such as sodium phosphate, sodium hexametaphosphate, potassium phosphate and calcium phosphate; silicates such as sodium silicate, sodium metasilicate and potassium silicate; alumina cement; Portland cement; The amount of addition is preferably 1% by mass or more and 15% by mass or less in terms of the proportion of the refractory material. More preferably, it is 3% by mass or more and 10% by mass or less. In addition, depending on the type of binder, a curing accelerator may be added. Specific examples of hardening accelerators are calcium salts such as slaked lime, quicklime and calcium carbonate.

Fibers, metal powders, dispersants, aluminum lactates, CMC, etc. may also be added, if necessary. Specific examples of fibers are polypropylene, nylon, PVA, vinylon, polyethylene, acrylic, polyester, pulp, paper fiber, sepiolite, and the like. It is preferable to add 0.05% by mass or more and 1% by mass or less in terms of the ratio to the refractory material.

The hot spray repair material of the present invention is basically constructed by the dry method using any spraying device, like the conventional hot spray repair material. That is, the hot spray repair material of the present invention is conveyed to a nozzle by a spraying device as a spraying material, and construction water is added at or near the nozzle and sprayed. Part of the construction water may be added to the spray material in advance to prevent dust generation.

<Properties of alumina shot fine powder after use>
Table 1 shows an example of the chemical composition of the used alumina shot fine powder.
These used alumina shot fine powders were recovered by a cyclone after being used for shot blasting treatment for removing scales from the inner surface of stainless steel pipes for small-diameter oil country tubular goods. As can be seen from Table 1, the used alumina shot fine powder contains about 3 to 6% by mass of scale removed by shot blasting in terms of Fe ₂ O ₃ .
In this example, used alumina shot fine powder collected by a No. 3 cyclone containing about 4% by mass of scale in terms of Fe ₂ O ₃ was used. In the following description, the used alumina shot fine powder recovered by the No. 3 cyclone is simply referred to as used alumina shot fine powder.

FIG. 3 shows a stereomicroscopic photograph of alumina shot fine powder after use. The black dots seen in the photograph are scales.
FIG. 4 shows an SEM observation photograph of alumina shot fine powder after use. Also, FIG. 5 shows an SEM observation photograph of the alumina shot before use. Here, the used alumina shot fine powder contains scale as described above, and the scale is magnetic. Therefore, the SEM observation of the used alumina shot fine powder was performed on the magnetically separated product from which the scale was removed by magnetic separation.
The alumina shot before use shown in FIG. 5 consists of brown alumina. Brown alumina is dark brown, has a glass surface, is dense and hard. On the other hand, the fine alumina shot powder after use shown in FIG. 4 has a particle size of 0.2 to 0.4 mm, and has a rounded shape with chipped corners due to shot blasting. In the post-use alumina shot fine powder, although the corners were chipped, no cracks were observed.
From the stereoscopic microscope observation photograph in FIG. 3 and the SEM observation photograph in FIG. 4, it can be seen that the scale is mixed as a single substance or an aggregate of 10 to 50 μm smaller than alumina.

<Example of hot injection repair material>
The hot injection repair materials of Examples 1 to 3 and Comparative Example 1 shown in Table 2 were tested to evaluate their hot affinity adhesion to slag.
The test method is as follows.
A tap hole of φ20×H20 mm was formed in the upper surface of the magnesia medium-sized brick, and the tap hole was filled with electric furnace slag powder to a thickness of 5 mm. Each of the hot injection repair materials of Comparative Example 1 was filled to a thickness of 5 mm to prepare a test specimen. As the electric furnace slag, two types of slag with C/S = 0.55 and slag with C/S = 1.74 were used in order to see the effects of differences in slag basicity (C/S). .
The specimen was placed in an electric furnace and heat-treated under the following heating conditions. During the heat treatment, a cover made of magnesia brick was placed over the tap hole to prevent contamination of the electric furnace by slag. After the heat treatment, the specimens were cut and their states were observed for comparison.
- Heating conditions: The temperature was raised to 1650°C in an air atmosphere over 5.5 hours, held for 2.5 hours, and then allowed to cool naturally.

6A and 6B show cross-sectional observation photographs of each specimen. FIG. 6A is for slag basicity (C/S)=0.55, and FIG. 6B is for slag basicity (C/S)=1.74. In FIG. 6A and FIG. 6B, photographs of cross-sections of each specimen are shown in the upper row, and photographs of cross-sections in which the tap hole portion is masked in order to see the state of slag infiltration are shown in the lower row.

6A and 6B, the hot injection repair materials of Examples 1 to 3, in which the mass ratio of alumina-magnesia is in the range of 55:45 to 85:15, are the same as in Comparative Example 1, which does not contain alumina shot fine powder after use. Compared to the intermittent repair material, it is integrated with the slag, and it can be seen that the hot affinity adhesion with the slag is high. Moreover, in the hot injection repair materials of Examples 1 to 3, the high hot affinity adhesion with slag increases the viscosity of the slag, and as a result, the slag infiltration into the magnesia brick is suppressed. Recognize. Furthermore, among the hot injection repair materials of Examples 1 to 3, the hot injection repair material of Example 2, which has an alumina-magnesia mass ratio (70:30) in theoretical spinel, has the highest hot affinity adhesion with slag. It can be seen that the slag infiltration into the magnesia brick is suppressed. From this, it is considered that secondary spinels are generated in the hot injection repair materials of Examples 1 to 3.

In order to verify this, the cross section of the heat-treated specimen of Example 2 (in the case of slag basicity (C/S) = 0.55) was observed by SEM. The SEM observation photograph is shown in FIG. Figures (a) and (b) are cross-sectional SEM observation photographs of the body portion of the hot injection repair material, and Figure (c) is a cross-sectional SEM observation photograph of the interface portion with the magnesia brick.
As shown in FIGS. 7(a) and 7(b), pores of various sizes were observed in the main body of the hot injection repair material after heat treatment. From the size and shape of large to medium pores, it was presumed that they were caused by the melting of scales. On the other hand, the small pores are circular, and it is presumed that they are caused by foaming during melting of the hot injection repair material. In addition, as shown in FIG. 7(c), at the interface with the magnesia brick, a scattering of highly viscous melt was observed, and the slag melt reacted with or was trapped in the secondary spinel structure. It is considered that the slag infiltration was suppressed as a result.

Regarding the effect of the difference in slag basicity (C/S), as expected, slag infiltration into magnesia bricks increased with increasing slag basicity (C/S). However, the tendency of slag infiltration was the same in Examples 1 to 3 and Comparative Example 1. That is, in Examples 1 to 3, regardless of the difference in slag basicity (C/S), the thermal affinity adhesion with slag was improved compared to Comparative Example 1, and slag infiltration tended to be suppressed. there were.

Next, in order to confirm the effect of the scale contained in the alumina shot fine powder after use, the hot injection repair materials of Example 2 and Comparative Example 2 shown in Table 3 were evaluated for hot affinity adhesion with slag. We conducted a test to The test method was as described above, and slag with a basicity (C/S) of 1.74 was used.

Example 2 in Table 3 has the same composition as Example 2 in Table 2, and contains 70% by mass of alumina shot fine powder after use. On the other hand, in Comparative Example 2 in Table 3, 70% by mass of a magnetically separated product from which scale was removed by magnetic separation was blended.

FIG. 8 shows cross-sectional observation photographs of each specimen.
As can be seen from FIG. 8, in Comparative Example 2 using a magnetically separated product from which scale was removed by magnetic separation, integration with slag was not observed, indicating that hot affinity adhesion with slag was low. That is, it can be seen that the scale contained in the alumina shot fine powder after use acts like a sintering aid, thereby improving hot affinity adhesion with slag and hot compactness.

<Example of hot spray repair material>
In order to confirm that the effects of the hot injection repair material described above can also be obtained with the hot spray repair material, the hot spray repair materials of Example 4 and Comparative Example 3 shown in Table 4 were subjected to heat exchange with the slag. A test was performed to evaluate the interaffective adhesion. The test method was as described above, and slag with a basicity (C/S) of 1.74 was used.

FIG. 9 shows cross-sectional observation photographs of each specimen.
From FIG. 9, the hot spray repair material of Example 4, in which the mass ratio of alumina-magnesia in the matrix portion is in the range of 55:45 to 85:15, is the hot spray repair material of Comparative Example 3 that does not contain alumina shot fine powder after use. Compared to the repair material, it is integrated with the slag, and it can be seen that the hot affinity adhesion with the slag is high. That is, it was confirmed that the hot sprayed repair material can also provide the same effects as the hot injection repair material.

Next, in order to evaluate the slag erosion resistance particularly required for hot spray repair materials for slag line repair, the hot spray repair materials of Example 4 and Comparative Examples 4 and 5 shown in Table 5 were subjected to a slag erosion test. carried out. In addition, Example 4 in Table 5 has the same composition as Example 4 in Table 4, and the mass ratio of alumina-magnesia in the matrix portion is 71:29. On the other hand, Comparative Examples 4 and 5 in Table 5 have alumina-magnesia mass ratios of 47:53 and 22:78, respectively, and are examples in which the mass ratio of alumina shot fine powder after use is low.

The method of the slag erosion test is as follows.
20% by mass of water was added to each of the hot spray repair materials of Example 4 and Comparative Examples 4 and 5 shown in Table 5, and the mixture was poured into a formwork to prepare a construction body. At this time, a core was used so as to form a tap hole of φ20×H20 mm on the upper surface of the work. Then, the tap hole was filled with electric furnace slag powder to a thickness of 5 mm to obtain a test specimen. Two types of slag were used as electric furnace exhaust slag: slag with C/S=1 and slag with C/S=3 in order to examine the effects of differences in slag basicity (C/S).
The specimen was placed in an electric furnace and heat-treated at 1500°C for 3 hours. After the heat treatment, the specimen was cut and the maximum erosion amount and maximum infiltration amount were measured.

10A and 10B show cross-sectional observation photographs of each specimen and the measurement results of the maximum erosion amount and maximum infiltration amount. 10A shows the case of slag basicity (C/S)=1, and FIG. 10B shows the case of slag basicity (C/S)=3.
The slag erosion resistance is expected to decrease as the content of used alumina shot fine powder increases. No significant difference was observed due to the difference in fine powder content. On the other hand, when the basicity (C/S) of the slag was 3, as expected, as shown in FIG. For this reason, when particularly high slag erosion resistance is required, such as hot spray repair of a slag line in contact with slag with high basicity, the alumina-magnesia mass ratio of the hot spray repair material matrix part is 55: 45 ~ A range of 70:30, that is, a range from magnesia-rich spinel to theoretical spinel is preferred.

Claims (5)

Used alumina shot (hereinafter referred to as "used alumina shot") used in shot blasting for removing scales on the inner surface of steel pipes, in proportion to 100% by mass of the refractory material, and having a particle size of less than 1 mm contains 55 to 85% by mass of used alumina shot fine powder and 15 to 45% by mass of magnesia fine powder having a particle size of less than 1 mm, and the mass ratio of used alumina shot fine powder to magnesia fine powder (used alumina shot fine powder: magnesia fine powder) in the range of 55:45 to 85:15. The refractory material includes a coarse refractory material with a particle size of 1 mm or more and a fine refractory material with a particle size of less than 1 mm, and the mass ratio of the coarse refractory material to the fine refractory material (coarse refractory material A hot spray repair material in which the material: fine powder refractory material) is in the range of 30:70 to 55:45,
The coarse-grained refractory material is a basic refractory material,
The fine powder refractory material is used alumina shot (hereinafter referred to as "used alumina shot") used in shot blasting for removing the inner surface scale of the steel pipe, in a proportion of 100% by mass of the fine powder refractory material. ), containing 55 to 85% by mass of used alumina shot fine powder having a particle size of less than 1 mm and 15 to 45% by mass of magnesia fine powder having a particle size of less than 1 mm, and a mixture of used alumina shot fine powder and magnesia fine powder A hot spray repair material having a mass ratio (alumina shot fine powder after use:magnesia fine powder) in the range of 55:45 to 85:15. 3. The hot spray repair material according to claim 2, wherein the mass ratio of used alumina shot fine powder to magnesia fine powder (used alumina shot fine powder:magnesia fine powder) is in the range of 55:45 to 70:30. 4. The hot spray repair material of claim 2 or 3, wherein the coarse-grained refractory material comprises magnesia. The hot spray repair material according to any one of claims 2 to 4, wherein the alumina shot fine powder after use comprises brown alumina.

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