JP2012126610A - Baking repairing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a baking repairing material hardly generating heterogeneity and roughness of constitution even though using fragments of refractory brick.SOLUTION: This baking repairing material includes a refractory powder and an organic binder and is contained in a heat-disappearing bag and thrown in a furnace to be repaired. The material includes maximum 50 mass% fragments of refractory brick having a particle diameter of not smaller than 1 mm and not less than 9 mass% spheroidized particles having a difference of bulk specific gravity and the refrartory brick fragments of not greater than 0.5 and a particle diameter of not less than 1 mm in 100 mass% refractory powder.

Description

  The present invention relates to a seizure repair material that contains a refractory powder and an organic binder, and that is housed in a heat-burning bag and placed in a furnace to be repaired.

  For example, as a method for repairing the lining of a converter or an electric furnace, a method is known in which a flexible container bag containing a baking repair material of several hundred kg to several t is placed in a furnace immediately after tapping. The baking repair material is formed by adding an organic binder such as pitch or resin to a refractory powder mainly composed of electrofused magnesia.

  The flexible container bag is burned away by the heat of the furnace immediately after being put into the furnace. The fired repair material in the flexible container bag is developed in the damaged part of the furnace lining, followed by the dissipation of volatiles in the organic binder due to the heat of the furnace and the formation of carbon bonds due to the fixed carbon content of the organic binder. Solidify while. Hereinafter, this solidified material is referred to as a baked repair material construction.

  As disclosed in Patent Documents 1 to 3, from the viewpoint of effective utilization of resources, crushed material of used refractory bricks is reused as a part of the baking repair material. Specifically, in Patent Documents 1 and 2, a crushed material of used magnesia-carbon refractory brick (hereinafter referred to as “mag-carbon brick”) is blended in a baking repair material, and Patent Document 3 describes used magnesia. -Crushed refractory bricks (called mag-chrome bricks) are blended into the baking repair material.

  Although patent document 4 is not literature regarding a baking repair material, when blending a refractory brick crushed material into an irregular refractory material, the refractory brick crushed material may be a used product or an unused product. (See paragraph 0012 of Patent Document 4).

Japanese Patent Laid-Open No. 02-59476 JP 2004-162952 A JP 2007-45673 A JP 2004-161594 A

  According to Patent Document 2, it is said that the corrosion resistance can be improved by using a crushed material of used mag-carbon brick as a baking repair material. The reason is as follows. Used mag-carbon bricks have fine pores inside due to heat reception during use as bricks. In use as a baking repair material, the organic binder penetrates into the fine pores, and a carbon bond in which the carbon component in the crushed brick and the fixed carbon in the organic binder are integrated is formed. It is said that it contributes to the corrosion resistance improvement (see paragraphs 0030 and 0031 of Patent Document 2).

  However, in practice, it is difficult to improve the corrosion resistance of the baking repair material by using refractory bricks. According to the inventor of the present application, the main cause is considered as follows.

  As described above, in particular, the used refractory brick has fine pores inside, and therefore has a lower bulk specific gravity than the remaining refractory raw material constituting the baking repair material. Moreover, even if it is an unused refractory brick, the bulk specific gravity is small compared with the refractory raw materials generally used, such as electrofused magnesia and sintered magnesia. For this reason, regardless of whether it is used or unused, crushed refractory bricks are likely to segregate during construction.

  According to Patent Document 2, although the bulk specific gravity difference between the used mag-carbon brick crushed material and the remaining magnesia raw material is about 1 at most (see Table 1 of Patent Document 2), the seizure repair material is other Unlike a regular refractory, it is thought that a slight difference in bulk specific gravity between raw materials can cause segregation because it undergoes a process of charging during construction.

  Specifically, refractory brick crushed material is put into the furnace and tends to concentrate on the surface layer portion of the baking repair material developed in a mountain shape on the inner surface of the furnace. Since the refractory brick crushed material is a crushed product, the surface shape thereof is rough. Therefore, in the portion where the refractory brick crushed material is concentrated, a stone wall-like structure is constructed by the refractory brick crushed material. In this way, the structure of the construction body becomes uneven and rough.

  As a result, the construction body of the seizure repair material is likely to cause structural spalling between the portion mainly composed of refractory bricks and the remaining portion. That is, as explained in Patent Document 2, even if the refractory brick can form a continuous carbon bond between the crushed material and the matrix, the refractory brick crushed material will fall off without waiting for the end of its life due to melting. To do.

  Patent Document 2 discloses an example in which the adhesive strength with the work surface is improved by using the crushed material of used mag-carbon bricks. The test method described in the above does not reflect the problem of segregation in actual use.

  An object of the present invention is to provide a seizure repair material that is less likely to cause unevenness and roughening of the structure despite the use of refractory brick crushed material.

  According to one aspect of the present invention, there is provided a baked repair material that contains a refractory powder and an organic binder, is contained in a heat-burning bag, and is charged into a repair target furnace, and has a mass of refractory powder of 100 mass. % Of refractory bricks having a particle diameter of 1 mm or more and a spheroidized particle having a bulk specific gravity difference of 0.5 or less and a particle diameter of 1 mm or more with a pulverized refractory brick of 9 mm or less. A baking repair material containing at least mass% is provided.

  Since the bulk specific gravity of the spheroidized particles and the refractory brick is approximated, segregation between the spheroidized particles and the refractory brick is less likely to occur even after receiving an impact during the construction. For this reason, the spheroidized particles are interposed between the particles of the refractory bricks and the refractory bricks suppress the construction of the stone wall-like structure by the crushed materials. Thereby, the nonuniformity and roughening of a construction body structure are relieved.

  Conventionally, in the field of castable refractories, it has been known that the use of spheroidized particles in the ultrafine powder region with an average particle size of about submicron provides a bearing effect that reduces friction between coarser particles. It has been. Also in the present invention, the spheroidized particles can exhibit a bearing effect as long as they are spheroidized.

  However, the above-described effects of the present invention are not merely due to the bearing effect, but can be obtained only when the spheroidized particles are used in a coarse particle region having a particle diameter of 1 mm or more. If the particle size of the spheroidized particles is less than 1 mm, refractory bricks have little effect of separating the particles of the crushed material, so in the use as a baking repair material, the construction of stone-walled structures made of refractory brick crushed materials is suppressed. It is not enough for the effect.

  Hereinafter, the baking repair material by embodiment of this invention is demonstrated concretely. The baking repair material includes a refractory powder and an organic binder.

  The refractory powder consists of a coarse particle region having a particle diameter of 1 mm or more and a fine particle region having a particle diameter of less than 1 mm. The mass ratio between the coarse grain region and the fine grain region is not particularly defined, but will be determined by technical common knowledge of those skilled in the art from the viewpoint of bringing the grain size configuration close to the close-packed structure and obtaining practical corrosion resistance. Typically, 100% by mass of the refractory powder is preferably composed of a coarse particle region: 25 to 65% by mass and a fine particle region: 35 to 75% by mass.

  In the present specification, the particle size of the particle is d or more means that the particle is a particle size remaining on the sieve having an opening d defined in JIS-Z8801, and the particle size of the particle is less than d. Means a particle size passing through the same sieve.

  In the coarse-grained region, refractory brick crushed material and spheroidized particles are blended.

  As the refractory brick crushed material, for example, one or more crushed materials selected from mag-carbon brick and mag-chrome brick can be used. The refractory brick crushed material may be a used product, an unused product, or a mixture thereof.

  The bulk specific gravity of the refractory brick crushed material is not particularly limited as long as the difference from the bulk specific gravity of the spheroidized particles is 0.5 or less. As described above, in general, crushed refractory bricks have a lower bulk specific gravity than ordinary refractory raw materials. The bulk specific gravity of the refractory brick crushed material is, for example, 2.4 to 3.0.

  In the present specification, the bulk specific gravity is a measured value using a method defined in the measurement of magnesia clinker by the Gakushin method (Gakushin method 2). This measurement method is common in the refractory industry. This measuring method is described in, for example, “Refractory Notebook (1981 version)”, Refractory Technical Association, October 31, 1981, First Printing, pages 330-334. That is, the bulk specific gravity of the refractory brick crushed material and the spheroidized particles is measured using the method defined in this Gakushin Method 2. However, in Gakushin method 2, the particle size range of 2 to 3.36 mm of the target powder is measured, but in this specification, for the target powder having a particle size of 1 mm or more, the particle size is 1 mm or more and less than 25 mm. As for the target powder having a particle size of less than 1 mm, the particle size range of the object to be measured is not particularly limited, and the particle size of less than 1 mm is to be measured.

  By using a refractory brick having a bulk specific gravity as large as possible, it becomes possible to use a general refractory raw material or a raw material having a bulk specific gravity close to it as spheroidized particles, and as a whole baking repair material. The bulk specific gravity can be increased, which contributes to shortening the baking time by densifying the structure and increasing the thermal conductivity.

  From this viewpoint, the bulk specific gravity of the refractory brick crushed material is preferably 2.6 or more, more preferably 2.7 or more. Such crushed refractory bricks with a large bulk specific gravity can be realized by selecting and using parts with particularly little deterioration from used refractory bricks, or using crushed refractory bricks that are not used. it can.

  The ratio of the refractory brick having a particle diameter of 1 mm or more to the refractory powder is 50% by mass at maximum. If the amount exceeds 50% by mass, the blended amount of refractory bricks is too large, so even if spheroidized particles are used in combination, the proportion of coarse particles in the refractory powder will be too high, resulting in corrosion resistance. It will be difficult to ensure. The lower limit of the blending amount of the refractory brick having a particle diameter of 1 mm or more into the refractory powder is not particularly limited.

  The significance of using refractory bricks will be explained. When the refractory brick crushed material is a used product, it has a significance that resources can be effectively utilized by recycling by blending it with a baking repair material. Even if it is an unused product, for example, by using the waste generated in the manufacturing process of refractory bricks, it has the meaning that the waste that has been discarded can be effectively used. In addition, if the refractory brick crushed material is a refractory brick containing carbon such as mag-carbon brick, for example, it is repaired by baking, whether it is used or unused. By blending into the material, it contributes to increasing the carbon content of the entire baking repair material, and has the significance of being able to contribute to improving its corrosion resistance.

  When the blending amount of the refractory brick is too small, the significance of using this becomes small. From this viewpoint, the ratio of the refractory brick having a particle diameter of 1 mm or more to the refractory powder is preferably 10% by mass or more, and more preferably 20% by mass or more.

  Spheroidized particles refer to particles that have been spheroidized. As the spheroidizing method, for example, a rolling method, a pressure molding method, a high-speed airflow impact method, and the like are known.

  The rolling method refers to a process of bringing an object closer to a sphere by rolling. A growth method in which the particle size increases with rolling may be used, or a polishing method in which the particles are gradually polished to reduce the particle size may be used. This method can be performed using, for example, a rotary kiln, a rotating drum, a rotating pan, a rotating horizontal disk, or the like.

  The pressure molding method refers to a process of bringing an object close to a sphere by pressure molding. This method can be performed using, for example, a pelletizer or a briquetter.

  The high-speed airflow impact method refers to a process of bringing a target particle closer to a sphere by applying an impact to a target particle in a high-speed airflow. This technique can be performed using, for example, an impact treatment apparatus (for example, model NHS series) manufactured by Nara Machinery Co., Ltd.

  The spheroidized particles preferably have a sphericity of 0.7 or more, and more preferably 0.9 or more.

The sphericity is obtained by measuring an image of a sample particle photographed with a stereomicroscope (for example, SMZ-10 manufactured by Nikon Corporation) or a scanning electron microscope (for example, JXA-8600M manufactured by JEOL Ltd.) as an image analyzer (for example, Nippon Avionics Co., Ltd.). ) And obtain it as follows. A projected area S _A of the sample particles from the image of the sample particles are measured and the perimeter L. When the area of a perfect circle of the circumference L is S _B , the sphericity of the sample particle is defined as S _A / S _B.

  In addition, when the target powder mixed sufficiently uniformly is taken into the image analysis device, the sphericity is measured for any 100 particles adjacent on the image, and the average value is 0.7 or more, The target powder consists of spheroidized particles.

  The material for the spheroidized particles is not particularly limited, and for example, a magnesia material such as magnesia clinker, a magnesia-silica material such as olivine, a dolomite material, or an alumina material can be used.

  The bulk specific gravity of the spheroidized particles is not particularly limited as long as the bulk specific gravity difference from the refractory brick crushed material is 0.5 or less. As described above, when using a refractory brick having a large bulk specific gravity, the spheroidized particles must also have a large bulk specific gravity. In this case, for example, a magnesia raw material such as magnesia clinker should be used. Can do. In addition, when using a refractory brick having a small bulk specific gravity, it is necessary that the spheroidized particles have a small bulk specific gravity. In this case, for example, a porous refractory raw material such as lightweight magnesia or lightweight alumina is used. Can be used.

  Since the bulk specific gravity of the spheroidized particles and the refractory brick is approximated, the seizure of the spheroidized particles and the refractory brick is less likely to occur in the baked repair material even after being subjected to an impact during the construction. For this reason, the spheroidized particles have refractory bricks interposed between the crushed materials and suppress the construction of a stone wall-like structure by the refractory bricks. Thereby, the nonuniformity and roughening of a construction body structure are relieved.

  The ratio of spheroidized particles having a particle diameter of 1 mm or more to the refractory powder is 9% by mass or more. If it is less than this, the above-mentioned effect by the spheroidized particles cannot be obtained. The upper limit of the ratio of the spheroidized particles to the refractory powder is not particularly limited, but since the spheroidized particles are blended in a coarse particle region having a particle size of 1 mm or more, the proportion of the coarse particle region in the refractory powder is optimized. It will be apparent to those skilled in the art that the present invention is naturally limited from this viewpoint. The proportion of spheroidized particles having a particle diameter of 1 mm or more in the refractory powder is preferably 20% by mass or less, for example.

  The remainder of the coarse-grained region is, for example, magnesia clinker and electrofused magnesia, dolomite dolica, dolomite clinker, calcia clinker, calcia clinker, alumina, bauxite, alumina, spinel clinker. Spinel material such as carbon dioxide, carbonaceous material such as carbon black, silicon carbide material, silicon nitride material, other non-oxide material, and used mainly composed of at least one of these One or more selected from refractories can be used.

  The coarse particle region preferably contains particles having a particle size of 3 mm or more. Even if cracks occur in the refractory, propagation of the particles can be prevented. Although the maximum particle size of the coarse grain region is not particularly limited, for example, it is preferably less than 8 mm, and more preferably less than 10 mm.

  The raw material which comprises a fine grain area | region is not specifically limited, For example, each raw material illustrated above can be used similarly to the case of a coarse grain area | region. In addition, you may mix | blend a refractory brick crushed material and a spheroidized particle also in a fine grain area.

  From the viewpoint of alleviating segregation at the time of charging, most of the remainder of the refractory powder other than the pulverized pulverized product and the spheroidized particles, specifically, 90% by mass or more of the remaining part of the refractory brick, It is preferable to use raw materials having a specific gravity difference of 0.5 or less. This can be easily realized, for example, by using a refractory brick having a high bulk specific gravity as a crushed material.

  As the organic binder, a substance that forms a carbon bond with heat, for example, one or more selected from resins, saccharides, pitch, tar, and other bitumen can be used. Examples of the resin include phenol resin, furan resin, epoxy resin, melamine resin, and terpene resin. A curing agent such as hexamethylenetetramine may be used in combination with the resin. In this case, the curing agent is also included in the concept of the organic binder. Examples of the saccharide include monosaccharides such as glucose, fructose, galactose, and mannose, and disaccharides such as sucrose, maltose, lactose, cellobiose, and trehalose. Pitch and tar may be either petroleum-based or coal-based. A solvent containing, for example, a polyhydric alcohol may be used together with the resin and pitch, and in this case, the solvent is also included in the concept of the organic binder. When pitch and resin are used in combination, a solvent compatible with both is preferable.

  The organic binder preferably contains pitch and / or tar. In the pitch and tar, the softened state from heat reception to carbon bonding continues longer than that of the resin and saccharide. In the present invention, the spheroidized particles have the effect of suppressing the construction of stone-walled structures by refractory bricks by separating the particles of the refractory bricks regardless of the softening period of the organic binder. However, if the softened state of the organic binder is maintained for a long time, the effect of promoting the development of the baking repair material can be further obtained. In particular, when the furnace is tilted after the baking repair material is put into the furnace, the bearing effect due to the spheroidized particles tends to appear remarkably. By developing the baking repair material thinly, the effect of preventing the problem of segregation becomes more remarkable.

  The amount of the organic binder to be added is not particularly defined, but will naturally be determined based on the common general technical knowledge of those skilled in the art from the viewpoint of providing shape retention and strength that can be applied to the baked repair material. Typically, the amount of the organic binder used is preferably 2% by mass or more, and more preferably 3 to 15% by mass, based on 100% by mass of the refractory powder. When it is 3% by mass or more, strength and shape retention can be reliably obtained, and when it is 15% by mass or less, further corrosion resistance can be secured.

  Although this baking repair material may be comprised only with a refractory powder and a binder, it may further contain other additives.

  Examples of other additives include one or more selected from metal powders, viscosity modifiers, organic fibers, metal fibers, and coarse particles having a particle size of 10 mm or more.

  Examples of the metal powder include Fe powder, Cu powder, Al powder, metal Si powder, and Fe—Si alloy powder.

  Viscosity modifiers include kerosene, heavy oil, creosote oil, anthracene oil and other coal or petroleum-based oils, vegetable oils, animal oils, ethers, lactams such as caprolactam, acetanilides such as acetanilide and acetoacetanilide, and butylphenol. Examples include alkylphenols. The viscosity modifier has the effect of preventing dust generation and promoting flow. From the concept of viscosity modifier, the solvent used in the binder described above is excluded.

  Examples of the organic fiber include vinylon fiber, polyethylene fiber, polypropylene fiber, and pulp fiber, which have an effect of improving workability, heat insulation, and stress relaxation between heat. Examples of the metal fiber include stainless steel fiber, Fe fiber, Cu fiber, Al fiber, and Ni fiber.

  The seizure repair material is applied by a method in which it is housed in a thermally burnable bag and placed in a repair target furnace. The material of the heat-disappearing bag is not particularly limited as long as it is burned by the heat of the furnace, and for example, polypropylene can be used. The accommodation amount of the baking repair material accommodated in the heat burnout bag is not particularly limited. The bake repair material may be packed in a small package of about 3 to 10 kg and put into the furnace. However, since the segregation becomes particularly serious when the amount contained in the heat-burnable bag is large, it is significant to apply the present invention accordingly. Specifically, the significance is large when the capacity is 100 kg or more, and the significance is particularly significant when the capacity is 1 t or more.

  Table 1 shows examples and comparative examples of the baking repair material and evaluation results.

  The refractory powder composing the baking repair material is crushed and spheroidized with refractory bricks under the condition that the coarse particle region having a particle size of 1 mm or more: 65% by mass and the fine particle region having a particle size of less than 1 mm: 35% by mass. Various changes were made in the bulk specific gravity and particle size of the particles.

  In Table 1, the evaluation was performed as follows. 20 kg of the baking repair material of each example is accommodated in a flexible container bag, and the flexible container bag is dropped 5 m. The floor surface is preheated to about 800 ° C.

  Segregation resistance: Observe the longitudinal cross section of the center of the construction body after baking on the floor surface visually, and determine the resistance to segregation of refractory bricks in four stages: ◎, ○, △, and ×. evaluated.

  Shear strength: The center part in plan view of the construction body that has been baked on the floor is taken as a sample, and the four stages of ◎, ○, △, and X depending on the shear strength at the position of the substantially central part in the height direction of the sample Relative evaluation.

  Expandability: Relative evaluation was performed in four stages of ◎, ○, Δ, and × according to the spread dimensions of the baking repair material on the floor surface. In addition, the expansion dimension was made into the average value of the diameter about two orthogonal directions.

  Easily baked: Relative evaluation was made in four stages of ◎, ○, △, and × according to the short time from dropping of the flexible container bag to stopping of smoke generation derived from the organic binder in the baking repair material.

  Example A is a comparative example corresponding to a conventional baking repair material containing refractory brick crushed material but no spheroidized particles. Apparently, the expansibility is relatively good, but in the plan view of the construction body, refractory bricks with a particle size of 1 mm or more are accumulated in the shape of a stone wall without developing in the center, and from the stone wall-shaped deposit, A matrix portion having a particle diameter of less than 1 mm was developed so as to separate and exude. For this reason, it is inferior especially in the point of being hard to segregate. Moreover, since the stone wall-like deposits are thick, they are inferior in seizure. Moreover, since the continuity of the structure | tissue regarding the height direction of a construction body was impaired due to uneven distribution of refractory bricks, shear strength is also relatively small. It can be said that such a construction body is likely to cause structural spalling in actual machine use.

  Example B is a comparative example in which a part of the coarse-grained region of Example A was replaced with a spheroidized magnesia material having a bulk specific gravity of 3.4, which is generally used for baking repair materials. Despite the inclusion of spheroidized particles, no improvement effect is seen in terms of difficulty in segregation and shear strength as compared to Example A. In addition, although Example B contains spheroidized particles, the degree of segregation of the refractory brick crushed material on the surface side of the construction body was worse than that of Example A. For this reason, the shear strength of Example B is smaller than that of Example A. This is because in Example B, the bulk specific gravity of the spheroidized particles is 1.0 larger than that of the refractory brick crushed material, and the spheroidized particles have a smooth surface and little friction with other particles. This is thought to be due to the refractory particles sinking to the base side of the crushed material. From the results of Example B, it can be seen that the difficulty of segregation cannot be alleviated simply by spheroidizing the remainder of the refractory powder other than the crushed material.

  Examples C and D are comparative examples in which light weight magnesia having a bulk specific gravity of 2.9, which is not normally used for a baking repair material, is spheroidized and blended in the remainder of Example A other than crushed refractory bricks. Compared with B, the bulk specific gravity of the spheroidized particles and the refractory brick was approximated, but since the addition amount of the spheroidized particles was small, segregation resistance and shear strength were not improved.

  Examples E to G are examples in which the amount of spheroidized particles was increased as compared with Examples C and D, and improved in segregation resistance and shear strength. This is because not only the bulk specific gravity of the spheroidized particles approximates that of refractory bricks but also the amount of spheroidized particles is sufficient, so that spheroidized particles are extremely separated from crushed materials in the structure. Not because refractory bricks were mixed with crushed materials. In other words, the presence of spheroidized particles between the refractory bricks and the crushed material allowed the refractory bricks to be separated from each other, and the construction of the stone wall by the refractory bricks was suppressed and the homogenization of the structure was achieved.

  From the results of Examples C to G, when the ratio of crushed refractory bricks to the refractory powder is 50% by mass, in order to obtain an improvement effect in segregation difficulty and shear strength, % Is necessary. In the present invention, the proportion of refractory bricks in the refractory powder is limited to 50% by mass or less. If the ratio of the refractory bricks to the refractory powder is 50% by mass or less, it is obvious that the above effects can be obtained with 9% by mass or more of spheroidized particles.

  Examples H and I are examples in which, in Examples E to G, the remainder of the refractory powder other than the spheroidized particles was blended with lightweight magnesia that approximates the bulk specific gravity of the refractory brick and is difficult to segregate. Further improvement was observed.

  However, in Examples H and I, developability and baking time were relatively deteriorated. The reason why the developability deteriorated is that the separation of the aggregate constituting the coarse grain region and the matrix constituting the fine grain region was further suppressed, and the oozing of the matrix was suppressed. In addition to this, the reason why the baking time is deteriorated is considered to be that many raw materials having a small bulk specific gravity were used. That is, a raw material having a small bulk specific gravity has a low thermal conductivity.

  Examples E to I are acceptable or relatively inferior in developability and easy-to-burn. However, in the present invention, importance is placed on segregation resistance and shear strength rather than these characteristics. That is, the poor developability can be compensated for by a plurality of input operations. In addition, the poor seizure property is not a problem if sufficient construction time is secured. However, the difficulty of segregation and the shear strength represent the useful life of the construction body. In the present invention, even if the spreadability and easy seizure are sacrificed, the effect of improving the difficulty of segregation and the shear strength is regarded as important.

  Examples J to L are examples in which the bulk specific gravity of the refractory brick crushed material and the spheroidized particles was approximated by using an unused product having a large bulk specific gravity as the refractory brick crushed material in Examples EG. Excellent in segregation resistance and shear strength. Moreover, the expansion | deployment property and easy baking property were also improved because the bulk specific gravity as the whole baking repair material improved.

  Examples M, N, and O employ high bulk specific gravity materials generally used as magnesia materials as examples of spheroidized particles in Examples J, K, and L, respectively. Like L, it is excellent in segregation resistance or shear strength. Moreover, since the bulk specific gravity as a whole of the baking repair material is large, the spread due to the impact of dropping is large and the developability is excellent. In addition, the raw material having a thin construction thickness and a high bulk specific gravity has a high thermal conductivity, and therefore has excellent bakeability.

  Examples P and Q are comparative examples in which the particle size range in which the spheroidized particles are blended is changed to a fine particle region having a particle size of less than 1 mm, specifically, an ultrafine particle region having a particle size of less than 75 μm. As a result, at least the shear strength was inferior. This is presumably because the particle size of the spheroidized particles was too small, and the construction of the stone wall-like structure could not be suppressed by separating the particles of refractory bricks. From this result, it can be said that the particle size region in which the spheroidized particles are blended is a coarse particle region having a particle size of 1 mm or more.

  As mentioned above, although the specific example of this invention was demonstrated, this invention is not limited to this. For example, it will be apparent to those skilled in the art that various combinations and improvements are possible.

  The seizure repair material of the present invention can be widely used in a construction method that is housed in a heat-burning bag and put into a repair target furnace. For example, it can be widely used for repairing converters, electric furnaces, vacuum degassing furnaces, AOD furnaces, ladles, tundishes, blast furnace furnaces, and other molten metal containers.

Claims (2)

  A baked repair material that contains a refractory powder and an organic binder, is contained in a heat-disappearing bag, and is put into a furnace to be repaired, and a particle size of 1 mm or more in 100% by mass of the refractory powder Baking of refractory bricks containing up to 50% by mass of crushed material and 9% by mass or more of spheroidized particles having a bulk specific gravity difference of 0.5 or less and a particle size of 1 mm or more from the refractory brick crushed material Repair material.   The baked repair material according to claim 1, wherein the crushed refractory brick is a crushed magnesia-carbon brick having a bulk specific gravity of 2.6 or more.