How to use amorphous refractories

Abstract

To provide a method for using an amorphous refractory excellent in structural spalling resistance and heat spalling resistance.SOLUTION: According to the present invention, there is provided a method in which an amorphous refractory containing 7% or less of alumina cement containing calcium aluminate and 2% or more of alumina cement containing strontium aluminate blended in a total amount of 7% or more and less than 20% on a mass basis is used in an environment of being brought into contact with a melt of 1000°C or higher. There is provided a method in which an amorphous refractory containing alumina cement containing strontium aluminate in the amount of 5% or more and less than 20% is used in an environment of being brought into contact with the melt at 1000°C or higher. There is provided a method in which an amorphous refractory containing 7% or less of alumina cement containing calcium aluminate and 7% or more of alumina cement containing strontium aluminate blended in a total amount of 7% or more and less than 20% is used in an environment of being brought into contact with the melt at 800°C or higher. Preferably, the refractory raw material mainly includes alumina and contains magnesia.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method of using amorphous refractories that require high durability at high temperatures. In this specification, "x to y" representing a numerical range means x or more and y or less, including the boundary values.

Background Art

[0002] Refractories mainly used in steelworks are being converted from shaped refractories such as bricks to amorphous refractories as the number of bricklayers decreases. In particular, the steel bath part that contacts the molten steel in the ladle has been quickly converted to amorphous refractories and is adopted in many factories. The materials are generally alumina-magnesia refractories and alumina-spinel refractories with alumina as the main component and blended with magnesia and spinel.

[0003] Generally, refractories are weak against sudden temperature changes, especially when shrinkage occurs during cooling. For example, in shaped refractories, the joints that exist in large numbers open little by little, and since they absorb dimensional changes, almost no damage to the refractories occurs. On the other hand, in amorphous refractories, since there are no joints, the entire refractory has to absorb dimensional changes. Especially when the dimensional change is large, it often suffers from thermal spalling damage where cracks perpendicular to the operating surface occur.

[0004] Also, when the ladle moves while slag contacts the refractory surface of the steel bath part during steel receiving and casting, the slag often penetrates into the refractory and forms an infiltration layer. The generated infiltration layer has a high density and high elastic modulus compared to the original refractory, and is easily damaged by structural spalling parallel to the operating surface caused by differences in physical properties such as the occurrence of cracks and the thermal expansion rate between the original refractory, leading to a decrease in durability. In particular, as described above, the infiltration layer is likely to crack, and damage progresses due to partial peeling of the refractory and its progression caused by a complex factor of cracks due to structural spalling.

[0005] One known cause of slag infiltration is the influence of calcium oxide, which readily forms low-melting-point compounds with slag components. Calcium oxide is a component found as calcium aluminate in alumina cement, which is commonly used in monolithic refractories. Refractories require a short construction period, i.e., a short non-operation period, and generally need to develop sufficient strength for removal of the formwork the next day or 24 hours after pouring. For this reason, alumina cement, which develops curing strength faster than Portland cement, is used. Calcium oxide in alumina cement reacts with slag at high temperatures to produce low-melting-point compounds and create a liquid phase. This reduces the structural strength of monolithic refractories at high temperatures, making them more susceptible to the occurrence of structural spalling cracks.

[0006] To suppress the effects of slag due to the presence of calcium oxide, conventional efforts have focused on reducing the amount of cement used, such as developing low-cement or ultra-low-cement castable materials. Further research into reducing the amount of cement has progressed, and for example, Patent Document 1 proposes a refractory material that does not use alumina cement, using alumina sol. Its features include the absence of calcium oxide, the ability to be poured into construction, no problems with curing strength or spalling resistance, and excellent heat spalling resistance.

[0007] Studies are also being conducted on alumina cement that does not contain calcium oxide. For example, Patent Document 2 proposes a cement using strontium aluminate instead of calcium aluminate, and a refractory material using 0.2% to less than 20% by volume of it. Patent Document 3 similarly proposes a refractory material using 0.5% to 10% by volume of cement using strontium aluminate. Ceramics using strontium aluminate have little to no calcium oxide content, so they have poor reactivity with slag and hardly generate a wetting layer. In addition to corrosion resistance to slag at high temperatures, the strength after curing of these refractory materials containing strontium aluminate cement has also been studied. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2020-203807 [Patent Document 2] Japanese Patent Publication No. 2010-120843 Public Relations [Patent Document 3] Japanese Patent Publication No. 2017-066025 Public Relations [Overview of the project] [Problems that the invention aims to solve]

[0009] However, the above-mentioned conventional technology had the following problems. In other words, the technology described in Patent Document 1 does not consider fracture energy and is insufficient from the standpoint of suppressing damage at hot temperatures. The technology described in Patent Document 2 does not consider the hot mechanical properties of monolithic refractories. The technology described in Patent Document 3 only considers the improvement of thermal spalling resistance with respect to the hot mechanical properties and does not consider the most important fracture energy, and is insufficient from the standpoint of suppressing damage at hot temperatures.

[0010] The present invention has been made in view of the above, and aims to propose a method for using monolithic refractories that have excellent structural spalling resistance and heat spalling resistance, focusing on hot fracture energy. [Means for solving the problem]

[0011] The first method of using an amorphous refractory according to the present invention, which advantageously solves the above problems, is characterized by using an amorphous refractory in an environment in which it comes into contact with a molten material of 1000°C or higher, in which the refractory raw material contains 7% by mass or less of alumina cement containing 10 to 40% by mass of CaO as calcium aluminate, and 2% by mass or more of alumina cement containing 10 to 40% by mass of SrO as strontium aluminate, in a total amount of 7% by mass or more and less than 20% by mass. Furthermore, a more preferable solution for the first method of using an amorphous refractory according to the present invention is to use an amorphous refractory in which 10% by mass or more of alumina cement containing 10 to 40% by mass of SrO as strontium aluminate is added.

[0012] A second method for using an amorphous refractory material according to the present invention, which advantageously solves the above problems, is characterized in that the amorphous refractory material is used in an environment in which it comes into contact with a molten material of 1000°C or higher, and in which an alumina cement containing 10 to 40% by mass of SrO as strontium aluminate is added in an amount of 5% by mass or more and less than 20% by mass, without adding alumina cement containing calcium aluminate to the refractory material.

[0013] A third method for using an amorphous refractory material according to the present invention, which advantageously solves the above problems, is characterized by using an amorphous refractory material in an environment in which it comes into contact with a molten material at 800°C or higher, in which the refractory material raw material contains 7% by mass or less of alumina cement containing 10 to 40% by mass of CaO as calcium aluminate, and 7% by mass or more of alumina cement containing 10 to 40% by mass of SrO as strontium aluminate, in a total amount of 7% by mass or more and less than 20% by mass. Furthermore, a more preferable solution for the third method for using an amorphous refractory material according to the present invention is to use an amorphous refractory material in which 10% by mass or more of alumina cement containing 10 to 40% by mass of SrO as strontium aluminate is added.

[0014] Furthermore, the method of using any of the above-mentioned amorphous refractories according to the present invention is: (a) The temperature of the melt is 1200°C or higher. (b) The temperature of the melt is 1400°C or higher. (c) The refractory materials other than cement are mainly composed of alumina and contain magnesia. (d) The molten material contains molten iron or molten steel, and the amorphous refractory material is applied to the steelmaking vessel. These could be more preferable solutions. [Effects of the Invention]

[0015] According to the method for using monolithic refractories of the present invention, an appropriate amount of alumina cement containing strontium aluminate is blended. Furthermore, the amount of alumina cement containing calcium aluminate is limited or omitted. This significantly improves the hot fracture energy of the refractories, resulting in highly durable monolithic refractories that possess a high degree of both structural spalling resistance and thermal spalling resistance. This leads to a reduction in the unit consumption of refractories, as well as a reduction in labor load and costs due to reduced construction frequency. Furthermore, the reduction in demolition frequency leads to a reduction in the cost of disposing of demolition waste and the environmental burden. In addition, the reduction in the unit consumption of refractories also reduces the environmental burden associated with the production of raw materials. Thus, in addition to economic benefits, it is industrially useful as it also provides benefits such as reduced labor load and reduced burden on the natural environment. [Modes for carrying out the invention]

[0016] The embodiments of the present invention will be described in detail below. The following embodiments are illustrative of compositions and methods for realizing the technical concept of the present invention, and do not limit the configuration to those described below. In other words, the technical concept of the present invention can be modified in various ways within the technical scope described in the claims.

[0017] In the method of using the monolithic refractory material according to this embodiment, a portion of the alumina cement containing calcium aluminate is replaced with alumina cement containing strontium aluminate. The monolithic refractory material of this embodiment is primarily used in environments that come into contact with high-temperature molten materials of 1000°C or higher. In this case, the mixture consists of alumina cement containing calcium aluminate at a mass of 7% or less and alumina cement containing strontium aluminate at a mass of 2% or more, based on the mass of the refractory material raw material with a particle size of 8 mm or less, with alumina cement containing calcium aluminate at a mass of 7% or less and alumina cement containing strontium aluminate at a mass of 2% or more, for a total of 7% or more and less than 20%.

[0018] Conventional alumina cement contains 10-40% by mass of CaO. CaO is present in the cement as calcium aluminate in compositions such as 3CaO·Al2O3, CaO·Al2O3, and 12CaO·7Al2O3. Alumina cement containing strontium aluminate replaces the above CaO with SrO, and the CaO content is 3% by mass or less. In formulations containing alumina cement with calcium aluminate exceeding the upper limit, the CaO content in the amorphous refractory material is too high, leading to increased slag infiltration and a decrease in fracture energy at high temperatures above 1000°C. This worsens structural spalling resistance and thermal spalling resistance. If the alumina cement formulation containing strontium aluminate is below the lower limit, the effect of replacing calcium aluminate is too small. As a result, no improvement in structural spalling resistance or thermal spalling resistance can be expected. Preferably, the mixture contains 2% by mass or less of alumina cement containing calcium aluminate and 5% by mass or more of alumina cement containing strontium aluminate. More preferably, the mixture does not contain calcium aluminate. If calcium aluminate is not included, the mixture can be made to contain 5% by mass or more of alumina cement containing strontium aluminate, which can be used in environments where it comes into contact with high-temperature molten materials of 1000°C or higher. However, if 10% by mass or more of alumina cement containing strontium aluminate is included, the reduction in fracture energy at high temperatures of 1000°C or higher can be suppressed even if the mixture contains 7% by mass or less of alumina cement containing calcium aluminate.

[0019] Second, by incorporating 7% by mass or more of alumina cement containing strontium aluminate into the monolithic refractory and setting the blending amount of alumina cement containing calcium aluminate to 7% by mass or less, this monolithic refractory can be used in an environment where it comes into contact with a high-temperature melt at 800°C or higher, and its hot strength is improved compared to conventional materials. Furthermore, if 10% by mass or more of alumina cement containing strontium aluminate is incorporated, even if the blending amount of alumina cement containing calcium aluminate is within the range of 7% by mass or less, a decrease in fracture energy in the high-temperature range of 800°C or higher can be suppressed.

[0020] If the total blending amount of alumina cement is less than the lower limit, the flexural strength is low and it is not suitable as a monolithic refractory. If the total blending amount of alumina cement is above the upper limit, the pot life becomes too short and it is not suitable as a monolithic refractory for on-site construction.

[0021] The fracture energy at 1000°C is preferably 0.64 N / mm or more, more preferably 0.70 N / mm or more, and even more preferably 0.85 N / mm or more. The fracture energy at 1200°C is preferably 0.52 N / mm or more, more preferably 0.65 N / mm or more, and even more preferably 0.85 N / mm or more. The fracture energy at 1400°C is preferably 0.12 N / mm or more, more preferably 0.23 N / mm or more, and even more preferably 0.30 N / mm or more. Also, the hot strength at 800°C is preferably 21.0 MPa or more, more preferably 22.0 MPa or more. Further, the slag infiltration index is preferably less than 100, more preferably 50 or less, and even more preferably 30 or less, with the conventional material taken as 100.

[0022] Therefore, the monolithic refractory according to this embodiment has heat-resistant spalling resistance and thermal spalling resistance when used in an environment where it comes into contact with a high-temperature melt at 800°C or higher or 1000°C or higher. It is suitable for use in an environment where it comes into contact with a high-temperature melt at 1200°C or higher, and even more suitable for use in an environment where it comes into contact with a high-temperature melt at 1400°C or higher.

[0023] In this embodiment, it is preferable that the refractory raw material excluding the above cement has alumina as the main component and contains magnesia. Here, the main component means exceeding 50% by mass, and preferably 70% by mass or more. For example, it is an Al2O3 - 7% by mass MgO castable material. MgO can be contained in the range of 2 - 15% by mass.

[0024] The monolithic refractory according to this embodiment can be widely applied to containers and devices that handle hot metal discharged from a blast furnace, refined molten steel, etc. Examples include a hot metal ladle, a molten steel ladle, a vacuum degassing device, a tundish, etc. For example, it is suitable to replace and use it in places where cracking of existing monolithic refractories mainly composed of alumina, such as structural spalling resistance and heat spalling resistance, is a problem. Also, considering the reaction with slag, it may be applicable to places that are currently shaped refractories in some cases. Although hot metal and molten steel are exemplified as the high-temperature melt, it can also be applied to other high-temperature melts.

Examples

[0025] Hereinafter, the present invention will be described in detail based on examples. The hot properties of a monolithic refractory blended with an alumina cement containing strontium aluminate were investigated. <e [Test levels] As a comparative example (No. 12), a monolithic refractory composed of a refractory raw material with a maximum particle size of 8 mm or less and containing no coarse aggregate, blended with 7% by mass of magnesia, was used. An alumina cement containing 7% by mass of calcium aluminate is used in this monolithic refractory.

[0026] As Examples No. 1 to 11 and 13, a base material was prepared by removing the alumina cement from the monolithic refractory of Comparative Example No. 12. As an alumina cement containing calcium aluminate (hereinafter simply referred to as alumina cement), commercially available Denka High Alumina Cement H was prepared, and as an alumina cement containing strontium aluminate (hereinafter referred to as SrO cement), Denka High Alumina Cement Super A09N was prepared.

[0027] Workability and hot properties were evaluated using the monolithic refractories with the formulations shown in Tables 1 and 2. No. 12 is a conventional monolithic refractory with 7% by mass of alumina cement and no SrO cement. Nos. 1 and 2 are monolithic refractories in which a portion of the alumina cement in No. 12 is replaced with SrO cement. Nos. 3 and 4 are monolithic refractories with 5% by mass and 7% by mass of SrO cement, respectively, and no alumina cement. Nos. 5-11 and 13 are monolithic refractories in which the amount of SrO cement is increased compared to No. 4. Nos. 14-18 are monolithic refractories with 10% by mass or more of SrO cement and also containing alumina cement. In addition, the amount of water added during mixing was kept constant at 6% by mass of the total amount of refractory material for all levels.

[0028] [Evaluation Method] <Workability> Regarding workability, the monolithic refractories of each level were mixed and placed in plastic bags. The tap flow value (mm) was measured immediately after mixing and every 0.5 hours according to the method specified in JIS R2521:1995. The tap flow value immediately after mixing and the pot life (Hr) are shown together in Tables 1 and 2. Pot life (Hr) is defined as the time at which the tap flow value falls below 130 mm. A pot life of 2 hours or more was considered an indicator of on-site workability.

[0029] <Hot properties> Hot properties were evaluated using slag penetration, hot bending strength, hot fracture energy, and dynamic modulus ratio from the spalling test, and the results are shown in Tables 1 and 2. Slag penetration was evaluated using a rotating drum test. Synthetic slag was used in which the ratio of calcium oxide content to silicon dioxide content was 3:1, and the value of iron oxide content in the slag converted to Fe (T.Fe) was 14 mass%. After mixing the 17 levels of compound material other than No. 13, they were cast into trapezoidal columnar molds, cured and dried, and then fired in the air at 1650°C for 3 hours to obtain 5 test specimens for each level. One test specimen each from the 12 levels was assembled into a cylindrical shape, heated to 1650°C, and synthetic slag was added. The slag was discharged and new slag was added every 30 minutes, and the test was conducted for a total of 2 hours. The test was conducted five times. After each test, the total thickness of the erosion and the discoloration caused by slag penetration was measured for each specimen, and the average of the five measurements was calculated. The ratio of the average value for each level to the average value of No. 12 was evaluated using an index with No. 12 set to 100. A smaller index indicates better resistance to slag penetration.

[0030] Hot bending strength measurements were performed in an air atmosphere at 200°C intervals between 800°C and 1400°C, and the hot fracture energy was calculated from the load-displacement curve. After mixing the refractory raw materials of 17 different formulations (excluding No. 13), the mixtures were cast into rectangular molds measuring 40mm x 40mm x 160mm and cured at 20°C room temperature for 24 hours. Subsequently, drying was performed at 110°C for 24 hours, followed by atmospheric firing at 1650°C for 3 hours, yielding five test specimens for each formulation. The test specimens were set in a hot bending tester and heated to various temperatures up to 1400°C, after which a three-point bending test was performed with a crosshead speed of 0.5mm / min and a support distance of 100mm. Furthermore, the hot fracture energy was calculated from the load-displacement curve of the test. Evaluation of both hot bending strength and hot fracture energy was performed by comparing the average values ​​of the five specimens for each formulation.

[0031] For the Spalling test, the 17 formulations (excluding No. 13) were mixed and then cast into rectangular molds measuring 30mm x 30mm x 120mm. The mixtures were cured at 20°C room temperature for 24 hours. After drying at 110°C for 24 hours, the mixtures were fired in the air at 1650°C for 3 hours, yielding five test specimens for each formulation. The dynamic modulus E0 was measured after specimen preparation. The specimens were placed in an electric furnace heated to 1400°C for 15 minutes, then allowed to cool in a room at 20°C. After the temperature dropped to room temperature, the dynamic modulus was measured again. This process was repeated, and the ratio E3 / E0 between the dynamic modulus E3 after the third test and the value E0 before the test was calculated. Five specimens were tested for each formulation, and the average value for each formulation was calculated for comparative evaluation.

[0032] [Table 1]

[0033] [Table 2]

[0034] The workability evaluation revealed that only test specimen No. 13, with a SrO cement content of 20% by mass, showed a tap flow value of 100 mm immediately after mixing, indicating no fluidity whatsoever. All other levels showed tap flow values ​​exceeding the target lower limit of 130 mm. Because specimen No. 13 lacked fluidity and could not be properly cast, it was not possible to create a test specimen for evaluating its hot properties.

[0035] The results of the pot life evaluation are explained below. As the amount of SrO cement added increased, there was a tendency for the pot life to decrease. All levels, except for No. 13, which showed no fluidity at a tap flow of 100 mm immediately after mixing, exceeded the target of 2 hours. Therefore, Nos. 1 to 11 are suitable for on-site construction, similar to conventional monolithic refractories.

[0036] The evaluation results for slag penetration are explained below. The results are greatly influenced by the amount of alumina cement used, and there is a large difference between Nos. 1, 2, and 12, which use ordinary alumina cement, and the other levels (Nos. 3 to 11) which use SrO cement alone. The slag penetration index of monolithic refractories using SrO cement alone was very low. However, in levels where the amount of SrO cement used was 10% by mass or more and ordinary alumina cement was used (Nos. 14 to 18), a similar slag penetration index was obtained compared to levels (Nos. 8 to 10) which used SrO cement alone with a similar total amount of SrO cement and ordinary alumina cement.

[0037] The results for hot bending strength are explained below. Compared to No. 12, high strength was observed at 800°C and 1000°C with a SrO cement content of 7 mass% or more. High strength was also observed at 1200°C with a SrO cement content of 2 mass% or more, and at 1400°C with a SrO cement content of 5 mass% or more. Furthermore, at each temperature, when no ordinary alumina cement was added, an increase in strength was observed with increasing SrO cement content, and particularly high strength was observed when the SrO cement content was 10 mass% or more. At a SrO cement content of 14 mass% or more, there was almost no change in strength, or conversely, it decreased. At levels with a SrO cement content of 10 mass% or more and using ordinary alumina cement (Nos. 14-18), comparable hot bending strength was obtained compared to levels using SrO cement alone with a similar total amount of SrO cement and ordinary alumina cement (Nos. 8-10).

[0038] This section explains the hot fracture energy calculated from the hot bending test results. At 800°C, the energy gradually decreased up to 5% by mass of SrO cement, then began to increase. The rate of increase was high from 9% to 12% by mass of SrO cement, and it was higher than No. 12 at 10% by mass or more. Furthermore, at 11% by mass or more of SrO cement, the values ​​were almost the same or showed a gradual decreasing trend. From 1000°C to 1400°C, the hot fracture energy increased with increasing SrO cement content up to 14% by mass. At 14% by mass or more of SrO cement, the values ​​were almost the same or showed a gradual decreasing trend. The increasing trend of hot fracture energy at 5% by mass or more of SrO cement was almost the same as that at 800°C. At levels where the SrO cement content was 10% by mass or more and ordinary alumina cement was used (Nos. 14-18), comparable hot fracture energy was obtained compared to levels where SrO cement alone was used, with a similar total amount of SrO cement and ordinary alumina cement (Nos. 8-10).

[0039] The results of the spalling test are as follows: From No. 12 to No. 1, 2, and 4, the dynamic modulus ratio E3 / E0 increased almost linearly with increasing SrO cement content while the total cement content remained the same. Between No. 5 and No. 7, the dynamic modulus ratio E3 / E0 increased sharply with increasing SrO cement content. The increase was largest between No. 6 and No. 7. From No. 7 to No. 10, with SrO cement content ranging from 11 mass% to 17 mass%, a consistently high dynamic modulus ratio E3 / E0 was observed. In No. 11, with a SrO cement content of 19 mass%, the dynamic modulus ratio E3 / E0 decreased slightly. From No. 1 to 11, a higher dynamic modulus ratio, i.e., higher heat spalling resistance, was observed than in No. 12. Furthermore, even at levels where the SrO cement content was 10 mass% or more and alumina cement was normally used (No. 14 to 18), a higher dynamic modulus ratio, i.e., higher heat spalling resistance, was observed than in No. 12. In particular, when the SrO cement content (without conventional alumina cement) was 11% by mass or higher, the values ​​were more than 15% higher than those of No. 12. Furthermore, the relationship between the dynamic modulus ratio E3 / E0 was almost identical to the relationship between the fracture energies.

[0040] As mentioned above, structural spalling occurs due to both slag infiltration and crack formation. Compared to No. 12, a typical monolithic refractory, Nos. 1-11 and 14-18 exhibit less slag infiltration, higher hot strength and high hot fracture energy at temperatures above 1000°C, which is the practical operating temperature range, and can be considered refractories with high structural spalling resistance. Furthermore, it was confirmed that high hot fracture energy leads to high heat spalling resistance. In addition, Nos. 3-11, which do not contain alumina cement with calcium aluminate, were found to have superior slag wetting resistance. At levels where the SrO cement content was 10% by mass or more and ordinary alumina cement was used (Nos. 14-18), comparable slag infiltration index, hot flexural strength, and hot fracture energy were obtained compared to levels where SrO cement alone was used with a similar total amount of SrO cement and ordinary alumina cement (Nos. 8-10). This indicates that even with the inclusion of ordinary alumina cement, superior structural spalling resistance and slag wetting resistance can be achieved. From this, it was found that if the SrO cement content is 10% by mass or more, the decrease in structural spalling resistance and slag wetting resistance can be suppressed even when ordinary alumina cement is included.

[0041] Furthermore, it was found that Nos. 4-11 and 14-18, which contain 7% or more by mass of SrO cement, exhibit superior hot strength at 800°C compared to No. 12, a typical monolithic refractory.

[0042] Although embodiments applying the present invention have been described above, the present invention is not limited by the descriptions that constitute part of the disclosure of the present invention in these embodiments. Furthermore, although a general alumina-magnesia monolithic refractory for ladles has been described as an example, since the effect is due to a change in the cement used in the monolithic refractory, all monolithic refractory other than those listed in the above embodiments are included in the technical scope of the present invention. Moreover, all other embodiments, examples, and operational techniques made by those skilled in the art based on these embodiments are also included in the technical scope of the present invention. [Industrial applicability]

[0043] According to the method of using the monolithic refractory material of the present invention, it exhibits excellent structural spalling resistance and heat spalling resistance when used as a monolithic refractory material in contact with high-temperature molten materials, making it highly durable when used in containers that hold high-temperature molten materials. In addition to reducing the unit cost of using refractory material, it leads to a reduction in workload and costs due to a reduction in construction frequency. Furthermore, since the frequency of demolition is also reduced, it leads to a reduction in the cost of disposing of demolition waste and the environmental burden. In addition, the reduction in the unit cost of using refractory material also reduces the environmental burden associated with the production of raw materials. Thus, the present invention is industrially useful as it offers economic benefits as well as a reduction in labor burden and the burden on the natural environment.

Claims

1. A monolithic refractory material is prepared by blending an alumina cement containing 10 to 40% by mass of calcium aluminate (CaO) in an amount of 0% to 7% by mass, and an alumina cement containing 10 to 40% by mass of strontium aluminate (SrO) in an amount of 5% by mass or more, in a total amount of 7% to less than 20% by mass, in the refractory material, and using it in an environment in which it comes into contact with a molten material at 1000°C or higher. A method for using monolithic refractories, wherein the fracture energy of the monolithic refractories at 1000°C is 0.69 N / mm or more.

2. A method for using an unshaped refractory material according to claim 1, wherein the unshaped refractory material is formulated with 10% by mass or more of alumina cement containing 10 to 40% by mass of SrO as strontium aluminate.

3. In a refractory material, instead of incorporating alumina cement containing calcium aluminate, an alumina cement containing 10 to 40% by mass of strontium aluminate (SrO) is incorporated in an amount of 5% to less than 20% by mass. This monolithic refractory material is used in an environment where it comes into contact with a molten material at 1000°C or higher. A method for using monolithic refractories, wherein the fracture energy of the monolithic refractories at 1000°C is 0.68 N / mm or more.

4. A monolithic refractory material is prepared by blending an alumina cement containing 10 to 40% by mass of calcium aluminate (CaO) in an amount of 0% to 7% by mass, and an alumina cement containing 10 to 40% by mass of strontium aluminate (SrO) in an amount of 10% to 20% by mass, in a total amount of 10% to 20% by mass, and using this material in an environment where it comes into contact with a molten material at 800°C or higher. A method for using monolithic refractories, wherein the fracture energy of the monolithic refractories at 800°C is 2.23 N / mm or more.

5. A method for using an amorphous refractory material according to any one of claims 1 to 4, wherein the temperature of the molten material is 1200°C or higher.

6. A method for using an amorphous refractory material according to any one of claims 1 to 4, wherein the temperature of the molten material is 1400°C or higher.

7. A method for using an amorphous refractory material according to any one of claims 1 to 4, wherein the refractory material material excluding cement is mainly composed of alumina and contains magnesia.

8. The molten material includes molten iron or molten steel, The method for using the monolithic refractory material according to claim 7, wherein the monolithic refractory material is applied to a steelmaking container.

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