JP7841972B2 - Shrinkable refractory material, method for manufacturing the same, and refractory lining structure for blast furnace tuyeres - Google Patents

Description

This invention relates to a shrinkable refractory used in blast furnace tuyeres, a method for manufacturing the same, and a refractory lining structure for blast furnace tuyeres containing this shrinkable refractory.

Figure 1 shows a typical refractory lining structure for a blast furnace tuyere (hereinafter also simply referred to as the "tuyere structure"). The blast furnace tuyere exists around the entire circumference (360 degrees) of the blast furnace, and the number of tuyeres varies depending on the size of the furnace body, but there are typically 20 to 40 tuyeres. Figures 1(a), (b), and (c) show a front view, A-A' cross-sectional view, and B-B' cross-sectional view of the tuyere structure as seen from inside the furnace, respectively. The tuyere structure is constructed so that the tuyere refractory material 1 covers the tuyere cooling device 2, and is installed between the upper tuyere refractory material or cooling plate 3 and the lower tuyere refractory material 4. The tuyere refractory material 1 is generally divided into upper and lower sections around the tuyere, consisting of the upper tuyere refractory material 1.a and the lower tuyere refractory material 1.b.

During operation, thermal expansion of the refractory material 4 at the lower part of the blast furnace tuyere causes it to push up, and damage to the cooling plate 3 and leakage of furnace gas due to gaps caused by this pushing up have been problematic. Patent Document 1 describes a design to mitigate this pushing up by filling the space between the tuyere cooling device 2 and the tuyere refractory material 1 with a shrinkable mortar 5, which is an amorphous refractory material, as shown in Figure 1, to absorb the expansion of the refractory material 4 at the lower part of the tuyere.

This shrinkable mortar is also called cushion mortar. Patent Document 1 discloses an amorphous refractory that achieves both slag resistance and shrinkability by incorporating silicon carbide powder, which has excellent slag resistance, to prevent molten slag infiltration near the tuyeres. The shrinkable mortar is inserted into joints during construction to absorb thermal expansion when the molten metal container is heated.

In the structure of Patent Document 1, shrinkable mortar 5 is applied only between the tuyere refractory 1 and the tuyere cooling device 2. Therefore, although the uplift phenomenon between the tuyere refractory 1 and the tuyere cooling device 2 can be expected to be mitigated, it is not possible to absorb the expansion at the point where the upper tuyere refractory 1.a and the lower tuyere refractory 1.b are in direct contact. Thus, the structure of Patent Document 1 is not a structure that can absorb the expansion around the entire circumference of the blast furnace tuyere, and it is not possible to completely suppress the uplift of the tuyere refractory 1. Therefore, gaps tend to occur, especially at the top of the blast furnace tuyere, and it has been a problem that these gaps must be filled from the outside with press-fitting material or the like to prevent the leakage of furnace gas during the initial operation period after blast furnace renovation work. In addition, in recent blast furnaces, a structure in which a cooling plate is introduced to the bell-shaped section above the tuyere is common in order to prevent the disappearance of the bell-shaped refractory. The cooling plate is a water-cooled structure and is fixed to the steel shell. Therefore, in conventional lining structures using cushion mortar, there is a risk of deformation and damage to the cooling plate when the refractory material 4 at the bottom of the tuyeres undergoes thermal expansion. Consequently, a structure that absorbs the thermal expansion of the refractory material throughout the entire blast furnace tuyeres is required.

To suppress the upward thrust of the entire blast furnace tuyere, Patent Document 2 proposes a structure in which a shrinkable refractory 9 is installed not only on the contact surface between the tuyere refractory 1 and the tuyere cooling device 2, but also around the entire circumference of the refractory constituting the blast furnace tuyere, as shown in Figures 2 and 3. Specifically, in Figure 2, the shrinkable refractory 9 is introduced between the lower tuyere refractory 1.b and the lower tuyere refractory 4, and in Figure 3, it is introduced between the upper tuyere refractory 1.a and the lower tuyere refractory 1.b, and applied around the entire circumference, absorbing the thermal expansion of the blast furnace tuyere. Since these shrinkable refractory materials 9 are introduced as mortar made by mixing water and refractory powder, their strength during construction is low. Therefore, to prevent deformation due to the load of the refractory constructed above the shrinkable refractory 9 during construction, the refractory above the shrinkable refractory 9 is supported by a support material 10 during construction.

Japanese Patent Publication No. 2007-291415 Japanese Patent Publication No. 2019-167599

Figure 4 shows the structure of a conventional shrinkable refractory. Conventional shrinkable refractories are amorphous refractories, and are formed by mixing inorganic particles 12 and inorganic fibers 13 with a liquid phase component 14 and then casting them. As a result, the constructed material contains a large amount of liquid phase component 14, as shown in Figure 4(a). In other words, because conventional shrinkable refractories are soft during construction, a support material for the upper refractory is necessary when applying them to structural parts where the load of the upper refractory is applied.

However, the introduction of support members poses problems with workability because the metal fittings that serve as support members are welded during construction, which increases construction time. Furthermore, the difference in thermal expansion behavior between the fixed support members and the refractory material prevents sufficient expansion absorption. Additionally, if the tuyere refractory material is damaged and the support members come into contact with the molten material, the support members melt, making it impossible to maintain the tuyere structure. Therefore, a refractory material and structure that can be easily constructed independently without the use of support members is desired.

The object of the present invention is to provide a shrinkable refractory that mitigates problems such as the upward thrusting phenomenon caused by thermal expansion of refractories, which is particularly likely to occur in the early stages of blast furnace operation. This shrinkable refractory possesses sufficient strength to withstand the load of the upper refractory without deformation during room-temperature construction without the use of support materials, while also exhibiting shrinkability against newly added loads (thermal stress loads) due to thermal expansion under high-temperature conditions during operation, as well as a refractory lining structure for the blast furnace tuyere.

The gist of this invention is as follows:
(1)
A fire-resistant material containing a total of 30 to 70% by mass of inorganic particles, at least partially containing silicon carbide particles, and a total of 30 to 70% by mass of alumina-based or silica-based inorganic fibers, and an adhesive,
The plate-shaped molded body has a laminated structure in which the inorganic particles are embedded in the voids of a mesh-like framework in which the inorganic fibers are intertwined.
The structure has inorganic particles embedded in the voids of a mesh-like framework in which the inorganic fibers are intertwined.
It contains 30% to 65% by mass of _{Al₂O₃ component} and 25% to 50% by mass of SiC component.
A shrinkable refractory material with a compressive strength of 0.5 MPa or higher at room temperature.
(2)
The shrinkable refractory material according to (1), wherein the inorganic fiber includes at least one selected from the group consisting of alumina fiber, mullite fiber, zirconia alumina silicate fiber, aluminosilicate fiber, and alkaline earth silicate fiber.
(3)
A shrinkable refractory material according to (1) or (2), which does not shrink under no load at 500°C and has a shrinkage rate of 30% or more under a load of 1.0 MPa.
(4)
A refractory lining structure for a blast furnace tuyere, comprising a tuyere refractory divided into upper and lower sections and a shrinkable refractory as described in (1) or (2),
The upper and lower sections of the aforementioned tuyere refractory are not supported by any support material from the iron shell.
The refractory lining structure for a blast furnace tuyere is provided, wherein the shrinkable refractory material is positioned between the upper and lower sections of the tuyere refractory material, or at least in the lower part of the tuyere refractory material.
(5)
A method for producing a shrinkable refractory material as described in (1) or (2),
A method for producing a shrinkable refractory, comprising the steps of: dispersing the aforementioned refractory material and an adhesive in a solvent to form a slurry; molding the slurry under pressure or under reduced pressure to form a plate-shaped molded body; and drying the molded body.

According to the present invention, even when refractory material is constructed on top without using support members during construction, a stable refractory lining structure of the blast furnace tuyere can be maintained without deformation. As a result, the installation of support members can be omitted, reducing work time, workload, and costs, and eliminating concerns about thermal expansion and melting of support members during operation. Thus, the present invention provides a simpler and less expensive way to prevent uplift onto the superstructure compared to conventional techniques.

The image shows a typical lining structure for a blast furnace tuyere, with (a) being a front view seen from inside the furnace, (b) being a cross-sectional view along A-A', and (c) being a cross-sectional view along B-B'. The diagram shows a tuyere structure in which an expansion absorption space is provided using a support material at the bottom of the tuyere refractory material, (a) is a front view seen from the inside of the furnace, (b) is a cross-sectional view along A-A', and (c) is a cross-sectional view along B-B'. The diagram shows a tuyere structure in which an expansion absorption space is provided using a support material between the upper and lower stages of the tuyere refractory material, (a) is a front view as seen from inside the furnace, (b) is a cross-sectional view along A-A', and (c) is a cross-sectional view along B-B'. The structure of conventional shrinkable refractories is schematically shown, with (a) representing the structure during construction, (b) during drying, and (c) after drying is complete. The structure of a shrinkable refractory, which is one embodiment of the present invention, is schematically shown, with (a) showing the structure during molding, (b) during drying, and (c) after drying is complete. One embodiment of the present invention shows a tuyere structure in which an expansion absorption allowance is provided at the bottom of the tuyere refractory using a shrinkable refractory, (a) a front view seen from the inside of the furnace, (b) a cross-sectional view along A-A', and (c) a cross-sectional view along B-B'. One embodiment of the present invention shows a tuyere structure in which an expansion absorption space is provided between the upper and lower stages of the tuyere refractory using a shrinkable refractory material, (a) a front view as seen from inside the furnace, (b) a cross-sectional view along A-A', and (c) a cross-sectional view along B-B'. A diagram showing the shape of the sample used in the corrosion resistance test.

The inventors investigated the standardization of a scalable refractory material in order to achieve a structure that possesses sufficient strength to withstand the load of the refractory material above without deformation during construction, without the use of support materials, while also achieving scalability to withstand the additional load (thermal stress load) added due to thermal expansion at high temperatures during operation.

The shrinkable refractory material of the present invention (hereinafter referred to as "this refractory material"), as shown in Figure 5, has a layered structure in which inorganic particles 12 are embedded in the voids of a mesh-like framework formed by intertwined inorganic fibers 13, and is a shaped refractory material having a structure containing numerous fine voids within the framework. By forming voids, the material exhibits shrinkability when a load is applied, as the voids collapse. On the other hand, the presence of voids reduces the strength of the refractory material, raising concerns that it may lack sufficient strength to withstand the load of the upper refractory material during construction. Therefore, inorganic particles are added to improve the strength of the material. That is, by filling the voids formed by the inorganic fibers with inorganic particles that have excellent strength, the overall strength of the shrinkable refractory material is improved. To achieve both strength improvement by inorganic particles and shrinkability improvement by inorganic fibers, this refractory material contains 30 to 70% by mass of inorganic fibers and 30 to 70% by mass of inorganic particles as a refractory material.

Furthermore, this refractory material contains, as a chemical composition, 30% to 65% by mass of _{Al₂O₃ component} and 25% to 50% by mass of SiC component. In other words, the total amount of _{Al₂O₃ component} and SiC component is 60% by mass or more. Since this refractory material is expected to come into contact with slag, it contains _{Al₂O₃ component} and SiC component to achieve both corrosion resistance and fire resistance.
The _Al₂O₃ component is effective in improving the refractoriness of refractories _; however, if the content is low, the refractoriness decreases and the material becomes more prone to melting. Furthermore, since _{the Al₂O₃} component is a major component of typical inorganic fibers, in this invention, its content is set to 30% by mass or more in order to maintain both refractoriness and shrinkability. On the other hand, this refractory material is applied to the tuyeres of blast furnaces and is susceptible to erosion by slag inside the furnace, so a balance between corrosion resistance and refractory properties is required. Therefore, in order to introduce a SiC component with excellent corrosion resistance into the refractory structure, _{the Al₂O₃} component is set to 65% by mass or less.

This refractory material uses silicon carbide particles as at least a portion of the inorganic particles. Alumina particles may also be included. The primary purpose of the silicon carbide particles is to improve corrosion resistance during actual furnace use, but they also serve as a filler, increasing the density and strength of the shrinkable refractory material. To ensure corrosion resistance and material strength, the SiC component is 25% by mass or more. On the other hand, since the shrinkability of this refractory material is ensured by voids within the structure of intertwined inorganic fibers, adding too many silicon carbide particles would reduce the proportion of inorganic fibers and decrease the material's shrinkability; therefore, the SiC component is 50% by mass or less.

This refractory material maintains a certain strength at room temperature while becoming shrinkable under high-temperature conditions (e.g., 500°C). The unique characteristic of this refractory material lies in its microstructure, which contains numerous minute voids at room temperature to high temperatures. These voids collapse under load, undergoing microscopic fracture, thereby distributing the pressure during compression and achieving shrinkability. Conversely, despite its microstructure containing numerous such voids, it maintains strength at room temperature and does not deform (shrink) under the load of the overlying refractory material.

Comparing the structure of this refractory material with that of conventional materials, conventional materials are amorphous refractories. During construction, as shown in Figure 4(a), a liquid component 14 containing a polyhydric alcohol as a solvent is present within the structure of inorganic particles 12 and inorganic fibers 13. During drying, as shown in Figure 4(b), the inorganic particles 12 and inorganic fibers 13 aggregate due to the evaporation of the liquid component. Therefore, after drying is complete, coarse voids of approximately 1 to 10 mm in size are formed, as shown in Figure 4(c). As a result, insufficient strength and variations in void size can easily lead to inconsistencies in shrinkability.

Therefore, the inventors attempted to achieve a uniform structure by uniformly dispersing inorganic particles and inorganic fibers by adding a sizing agent to a solvent. They also attempted to uniformly laminate inorganic fibers by performing pressurized or vacuum molding with the sizing agent added. Specifically, a slurry is prepared by adding a sizing agent to a refractory material (raw material formulation) containing inorganic particles and inorganic fibers, along with a solvent such as water. At this time, the inorganic particles 12 and inorganic fibers 13 are uniformly dispersed by coating them with the sizing agent. Subsequently, pressurized molding such as vacuum molding or press molding is performed. In these molding processes, applying pressure due to the internal-external pressure difference caused by pressurization or depressurization has the effect of removing solvent and large voids in the structure, and firmly bonding the inorganic particles and inorganic fibers. As a result, a structure is formed in which inorganic fibers 13 intertwined with inorganic particles 12, as shown in Figure 5(a), are uniformly laminated. Furthermore, because the inorganic particles 12 and inorganic fibers 13 are bonded together by the adhesive, aggregation does not occur even when the liquid component 14 volatilizes or evaporates, as shown in Figure 5(b). After drying is complete, a uniform void structure can be obtained as shown in Figure 5(c), preventing a decrease in strength.

In this refractory material, the key difference lies in the use of a binder rather than the hydraulic or thermosetting binders commonly used in refractories. Examples of hydraulic binders include alumina cement, Portland cement, magnesia cement, and gypsum, which harden through a hydration reaction. Refractories hardened using these hydraulic binders develop strength from room temperature to high temperatures, making it difficult to achieve adequate shrinkability at high temperatures. Examples of thermosetting binders include epoxy resins, phenolic resins, water glass, phosphoric acid, and phosphates. These thermosetting binders also generally develop strength in high-temperature environments, making it difficult to achieve adequate shrinkability at high temperatures.

The adhesive used in this invention also provides the strength necessary for shape retention to shrinkable refractories. Therefore, this refractory material can be handled as a fixed-shape refractory material in the same way as tuyere refractories during construction. Typical adhesives used in this invention include starches such as dextrin, wheat flour starch, potato starch, sweet potato starch, tapioca starch, rice starch, sago starch, corn starch, and high-amylose corn starch, as well as guar gum, locust bean gum, sanzan gum, karaya gum, agar, sodium alginate, gelatin, carrageenan, gum arabic, mannan, PVA, CMC, and MC. These can be used individually or in combination of two or more.

This refractory material achieves its strength at room temperature to high temperatures through bonding of refractory materials (inorganic particles and inorganic fibers) using an adhesive and pressurized or vacuum molding (hereinafter also referred to as "compression molding"). To withstand the load from the upper refractory material, it is preferable that the compressive strength at room temperature is at least 0.5 MPa. Furthermore, considering the impacts applied during installation, it is desirable to have a compressive strength of 5 MPa or more, and even more desirable to have a compressive strength of 10 MPa or more. Compression molding methods include pressurized molding such as CIP, HIP, hydraulic press, and flexion press, as well as vacuum molding, which involves casting under reduced pressure and utilizing the pressure difference with ambient air to densify the structure; any of these methods may be used. In addition to combining inorganic fibers and inorganic particles to create composite materials, compression molding allows for dense filling of the gaps in the mesh structure of the inorganic fibers with inorganic particles, thereby improving strength.

It is preferable that this refractory material be a standardized refractory material in the form of a plate (board). This allows for easy installation on top of the refractory material at the bottom of the tuyere section without the need for supporting materials, and furthermore, it enables stable installation of refractory material on top of this refractory material.
One of the objectives of this refractory material is to absorb the thermal expansion of the lower refractory material around the entire circumference of the tuyeres, and it can be applied without the use of support materials in areas around the tuyeres of a blast furnace where support materials were required with conventional amorphous refractory materials (mortar).

Based on temperature simulations of the tuyere structure conducted by the inventors using data from operational blast furnaces, it was anticipated that the region where this refractory material is used would reach a maximum temperature of 500°C during operation. Therefore, it is preferable that this refractory material has shrinkage characteristics corresponding to the thermal stress load caused by the thermal expansion of the tuyere refractory material, etc., from room temperature up to 500°C. On the other hand, it is preferable that it does not shrink from room temperature up to 500°C under loads other than thermal stress loads. That is, it is preferable that it does not shrink under no load at 500°C. Furthermore, it is preferable that the shrinkage rate under thermal stress load is 30% or more at 500°C and a load of 1.0 MPa. Therefore, it is preferable that the fibers forming the framework of this refractory material are alumina-based or silica-based inorganic fibers, specifically containing at least one of the following: alumina fibers, mullite fibers, zirconia alumina silicate fibers, aluminosilicate fibers, alkaline earth silicate fibers, etc.

In the tuyere structure using this refractory material, as shown in Figure 6, neither the upper tuyere refractory material 1.a nor the lower tuyere refractory material 1.a is supported by a support member from the steel shell 7. The refractory material 11 is positioned at the bottom of the tuyere refractory material 1, as shown in Figure 6, and at least one of the spaces between the upper and lower tuyere refractory materials, as shown in Figure 7, each serving as an expansion absorption space.

Furthermore, the method for manufacturing this refractory material includes the steps of: dispersing the above-mentioned refractory material and adhesive in a solvent to form a slurry; molding the slurry under pressure or under reduced pressure to form a plate-shaped molded body; and drying the molded body.
The amount of adhesive added can be approximately 0.1 to 5% by mass on the outside, relative to 100% by mass of the refractory material. Typically, water or an organic solvent can be used as the solvent, and the amount added should be adjusted appropriately to produce a slurry suitable for subsequent pressurized or vacuum molding.
Furthermore, drying can be carried out in an atmospheric environment at 100-120°C for approximately 12-24 hours.

Table 1 shows the material composition and component composition (chemical composition) of the examples and comparative examples of the present invention, as well as the evaluation results of their durability. Three types of fibers, A to C, were investigated as the fibers to be used. Fiber A was an alumina fiber, and fiber B was an aluminosilicate fiber, with the alumina components of fibers A and B being 70% by mass and 50% by mass, respectively. Fiber C was a vinylon fiber. Two types of inorganic particles, particle D and particle E, were also investigated as the inorganic particles to be used. Particle D was a silicon carbide particle, and particle E was an alumina particle. When a binder was used, it was added in an external amount of 1-2% by mass relative to the total amount of refractory material, i.e., fibers and particles. During the molding process, vacuum molding was performed as a reduced-pressure molding method, and uniaxial press molding at 0.5 MPa was performed as a pressure molding method. Drying was carried out in an atmospheric environment at 110°C for 24 hours to obtain plate-shaped samples.

The compression strength at room temperature was measured using a 100 mm x 100 mm pressure surface with a thickness of 40 mm, referencing JIS R2206.
To measure the shrinkage rate, a sample is cut out and filled into a bottomed cylindrical crucible with an inner diameter of φ25 mm and an open top, and the height _L0 of the sample is measured at this stage. In the examples and comparative examples, _L0 = 40 mm. Next, with the sample in the crucible kept uniformly at 500°C, the height _L1 of the sample is measured under no load. Then, a load of 1 MPa (approximately 10 kgf/ ^cm² ) is gently applied to the sample and held for 20 minutes, and the height _L2 of the sample is read when the amount of compression of the sample stabilizes. Here, the shrinkage rate under no load at 500°C is calculated as ( _L0 - _L1 ) / _L0 × 100%, and the shrinkage rate at 1 MPa at 500°C is calculated as ( _L0 - _L2 ) / _L0 × 100%.
Corrosion resistance (resistance to slag erosion) was evaluated using a rotary erosion tester. The drum lining was made of refractory silicon carbide, and samples with the shape shown in Figure 8 were filled into grooves formed in the lining. Blast furnace slag was charged into the drum, and the drum was rotated while the blast furnace slag was melted with a burner. After that, the erosion dimensions of the maximum erosion part of each sample were measured, and each measured value was divided by the erosion dimension of Example 1 and multiplied by 100 to show the relative value (erosion index). A higher erosion index indicates greater erosion. An erosion index of less than 80 was marked with ◎ (excellent), 80 to 100 with ○ (good), and over 100 with × (poor). Figure 8 shows a detailed view of the samples subjected to the rotary erosion tester. Refractory silicon carbide 17 was cut into a trapezoidal plate shape with a top edge of 65 mm, a bottom edge of 110 mm, and a depth of 65 mm. A groove 10 mm wide and 40 mm deep was made in the refractory silicon carbide material 17, and samples from each example were cut to fit the groove and filled in. Then, tests were conducted using these 10 samples.

Examples 1 to 5 of this refractory material, as shown in Table 1, did not shrink even at 500°C and all exhibited excellent corrosion resistance, shrinkability, and compressive strength at room temperature. This is thought to be because the inorganic fibers ensure voids within the structure, while the inorganic particles containing silicon carbide maintain material strength. As a result, both compressive strength at room temperature and shrinkability at 500°C are achieved. Furthermore, the use of silicon carbide particles significantly contributes to corrosion resistance. In addition, the addition of a sizing agent and the implementation of pressurized or vacuum molding treatment strengthen the bond between the inorganic fibers and inorganic particles, thereby improving the compressive strength at room temperature.

Comparative Example 1 is a typical composition of conventional shrinkable mortar applied in Patent Documents 1 and 2, and has excellent shrinkability due to its high inorganic fiber content. However, because no binder is added, the inorganic fibers are not uniformly dispersed, and since the mortar construction is dried without molding, it has an uneven structure due to the aggregation of fibers and particles during drying. Therefore, it lacks strength and is unsuitable.
Comparative Example 2 has a high proportion of silicon carbide particles, resulting in excellent overall material strength and corrosion resistance. However, it is unsuitable due to its low inorganic fiber content, which leads to poor shrinkability.
Comparative Example 3 exhibits shrinkability under a load of 500°C, but because it is a vinylon fiber that melts at around 250°C, it shrinks by about 25% even under no load at around 500°C, making it unsuitable. Furthermore, because it is an organic fiber, its corrosion resistance is also poor, making it unsuitable.
Comparative Example 4 exhibits excellent shrinkability, but is unsuitable due to insufficient compressive strength at room temperature because it contains few inorganic particles. Comparative Example 5, while exhibiting excellent strength and corrosion resistance at room temperature due to a large amount of inorganic particle addition and pressure molding, is unsuitable due to insufficient inorganic fibers and poor shrinkability.
Comparative Examples 6 and 7 are examples in which a hydraulic binder and a thermosetting binder were used as binders, respectively, and are unsuitable due to their poor shrinkability.

1. Tuyere refractory 1. a. Upper tuyere refractory 1. b. Lower tuyere refractory 2. Tuyere cooling device 3. Upper tuyere refractory or cooling plate 4. Lower tuyere refractory 5. Shrinkable mortar 6. Staves 7. Steel shell 8. Refractory poured in front of the staves 9. Shrinkable refractory layer 10. Support material 11. Main refractory 12. Inorganic particles 13. Inorganic fibers 14. Liquid components (water, organic solvents)
15. Void 16. Adhesive 17. Refractory material made from silicon carbide 18. Sample

Claims (5)

A fire-resistant material containing a total of 30 to 70% by mass of inorganic particles, at least partially containing silicon carbide particles, and a total of 30 to 70% by mass of alumina-based or silica-based inorganic fibers, and an adhesive,
The plate-shaped molded body has a laminated structure in which the inorganic particles are embedded in the voids of a mesh-like framework in which the inorganic fibers are intertwined.
It contains 30% to 65% by mass of _{Al₂O₃ component} and 25% to 50% by mass of SiC component.
A shrinkable refractory material with a compressive strength of 0.5 MPa or higher at room temperature. The shrinkable refractory material according to claim 1, wherein the inorganic fiber comprises at least one selected from the group consisting of alumina fibers, mullite fibers, zirconia alumina silicate fibers, aluminosilicate fibers, and alkaline earth silicate fibers. A shrinkable refractory material according to claim 1 or 2, which does not shrink under no load at 500°C and has a shrinkage rate of 30% or more under a load of 1.0 MPa. A refractory lining structure for a blast furnace tuyere, comprising a tuyere refractory divided into upper and lower sections and a shrinkable refractory according to claim 1 or 2,
The upper and lower sections of the aforementioned tuyere refractory are not supported by any support material from the iron shell.
The refractory lining structure for a blast furnace tuyere is provided, wherein the shrinkable refractory material is positioned between the upper and lower sections of the tuyere refractory material, or at least in the lower part of the tuyere refractory material. A method for producing a shrinkable refractory material according to claim 1 or 2,
A method for producing a shrinkable refractory, comprising the steps of: dispersing the aforementioned refractory material and an adhesive in a solvent to form a slurry; molding the slurry under pressure or under reduced pressure to form a plate-shaped molded body; and drying the molded body.