JP2010023057A - Refractory for molten metal nozzle and method for preventing suction of air from crack part thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the phenomenon that a refractory for a molten metal nozzle pouring out a molten metal from a molten metal vessel sucks air from cracks by heat spalling is prevented; to prevent the structural oxidation in the vicinities of the cracks of the refractory, further; to suppress structural deterioration; and to prevent the ioccurrence of steel leakage troubles as well. <P>SOLUTION: In order to suppress the phenomenon that, regarding a refractory 1 for a molten metal nozzle pouring out a molten metal from a molten metal vessel such as a laddle and a tundish, the atmospheric air is sucked from crack parts by heat spalling into a nozzle, the outer circumferential part of the refractory 1 for nozzle is coated with a crack clogging material 13 melted at a prescribed temperature, infiltrating into the crack 11, 12 parts, and clogging the crack 11, 12 parts. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a refractory for molten metal nozzles such as an upper nozzle, a sliding plate, an intermediate nozzle, and a lower nozzle for sliding nozzles used when flowing molten metal from a molten metal container such as a ladle or tundish in the metallurgical field. And a method for preventing atmospheric suction from the cracked portion.

  The sliding nozzle for molten steel casting flow control attached to the bottom of the ladle for steel making consists of an upper nozzle, a sliding plate, an intermediate nozzle, and a lower nozzle, and there is a fine space for joining called joints between each. Arise. Therefore, at the time of use, a mortar refractory or a packing refractory having a certain thickness previously formed in a donut shape is installed in the joint portion, and the gap is filled and used.

  However, an abnormal damage of the refractory often occurs from the joint as a starting point, and a steel leakage trouble that the molten steel flowing through the inner hole portion is discharged out of the furnace occurs. Factors that can be considered include misplacement of joint refractories, eccentricity, and cracks in the nozzle refractories. In addition, when a refractory material, particularly a refractory material for a nozzle, receives a very high temperature molten steel having a temperature of 1000 ° C. or higher in its inner hole, a crack is generated due to the influence of the thermal spall. At that time, a compressive stress is generated in the vicinity of the nozzle inner hole, and a tensile stress is generated in the outer periphery of the nozzle, and a crack is generated from the outer peripheral side. Thereafter, as the number of times of receiving steel increases, the crack expands and finally reaches the inner hole of the nozzle. The ultimate goal of the refractory industry is to develop refractories that do not crack at all, but this is not achieved with current technology.

  When the turtles reach the inner hole side of the nozzle, since the inner hole is in a negative pressure atmosphere, there is a possibility of sucking the outside air through the crack. If the joint refractory is completely installed and the joint refractory is slightly damaged, the air is not sucked, but it is often easy to suck air from the joint portion. When the atmosphere is sucked from the joint, the atmosphere enters the crack and the oxidation of the refractory structure near the crack proceeds. Furthermore, if the air suction is continued, the refractory structure will be weakly deteriorated. When damage to the nozzle progresses to such a state, the molten steel flowing through the nozzle hole destroys the deteriorated refractory structure, proceeds along the tortoise while melting, and finally reaches the outer periphery of the nozzle. It leads to leakage steel.

Conventionally, a sealing method for preventing air from being drawn in by a sliding nozzle or an immersion nozzle has been proposed as disclosed in JP-A-10-235457 and JP-A-2003-250605.
However, these are seals between the sliding nozzle fixed plate and the sliding plate, or between the sliding gate and the immersion nozzle junction, preventing air from being drawn in through the joints and packings between them. However, it did not prevent inhalation of air from the cracks generated by the sliding plate and the thermal spall of the nozzle.
JP-A-10-235457 JP 2003-250605 A

  The occurrence of cracks in refractories for nozzles due to thermal spalls is currently unavoidable. It can be prevented from entering the nozzle. Therefore, even if a crack occurs in the refractory for the nozzle due to the thermal spall, the atmosphere can not be infiltrated into the nozzle from the crack and the structure oxidation in the vicinity of the crack of the refractory can be prevented. The problem was to prevent it from occurring.

  In view of the above, the present invention is a refractory for a molten metal nozzle that discharges molten metal from a molten metal container such as a ladle or tundish in order to solve the above problems, and is a crack caused by thermal spalling. In order to suppress the suction of outside air from the inside of the nozzle into the nozzle, a crack closing material that softens or melts at the predetermined temperature for use to close the cracked portion is applied to the outer peripheral surface of the nozzle refractory. A refractory for a molten metal nozzle is provided.

  In addition, a crack closing material that softens or melts at a predetermined temperature on the upper surface and / or the lower surface portion of the molten metal refractory for a nozzle and enters the crack portion or covers the crack portion and closes the crack portion is 0.005. The present invention provides a refractory for a molten metal nozzle characterized by being applied in a thickness of ˜3 mm.

  Furthermore, it melts at a predetermined temperature between the nozzles of the refractories for molten metal nozzles, or the joint surface with the sliding plate, and the outer peripheral surface part thereof, penetrates into the crack part, or covers the crack part and closes the crack part. The present invention provides a refractory for a molten metal nozzle, characterized in that a crack plugging material is applied.

  Furthermore, there is provided a method for preventing atmospheric suction from a cracked portion of a refractory for a molten metal nozzle that discharges the molten metal from a molten metal container such as a ladle or tundish, which is used for an outer peripheral surface portion of the refractory for the nozzle. A crack closing material that softens or melts at a temperature to close the crack is applied in a thickness of 0.005 to 3 mm, preferably 0.1 to 0.5 mm, and heat is applied to the outer peripheral surface of the nozzle refractory. When cracks due to spalling occur, the crack plugging material applied to the outer peripheral surface portion is softened or melted to block the crack portion and to prevent the outside air from being sucked into the refractory. A feature of the present invention is to provide a method for preventing atmospheric suction from a crack portion of a refractory for a molten metal nozzle.

  Furthermore, the present invention provides a refractory for a molten metal nozzle, characterized in that a crack closing material is applied to the outer peripheral surface of the refractory for a molten metal nozzle in a thickness of 0.1 to 0.5 mm.

  The refractory for a molten metal nozzle of the present invention is a refractory for injecting a molten metal from a molten metal container such as a ladle or a tundish, and the outside air from the cracked portion caused by thermal spalling is nozzleed. In order to suppress suction inside, a crack closing material that softens or melts at a predetermined temperature of use and closes the cracked portion is applied to the outer peripheral surface portion of the nozzle refractory, so that the inner hole has a temperature of 1000 ° C. or higher. Even if a crack is generated due to the influence of the thermal spall, the crack closure material applied to the outer peripheral surface of the nozzle refractory melts and closes the crack. Inhalation of air from the refractory can prevent the oxidation of the structure near the crack of the refractory, suppress the deterioration of the structure, and prevent the occurrence of steel leakage.

  In addition, a crack closing material that softens or melts at a predetermined temperature on the upper surface and / or the lower surface portion of the molten metal refractory for a nozzle and enters the crack portion or covers the crack portion and closes the crack portion is 0.005. By coating with a thickness of ˜3 mm, even if there is a defect in the installation of the joint packing on the upper surface and / or lower surface of the nozzle refractory, the crack plugging material melts and closes the crack to the atmosphere Can be prevented from entering the inside of the nozzle, and as described above, the structure oxidation in the vicinity of the crack of the refractory can be prevented, the deterioration of the structure can be suppressed, and the occurrence of leakage steel can also be prevented.

  Furthermore, it melts at a predetermined temperature between the nozzles of the refractory for the molten metal nozzle or the joint surface with the sliding plate, and the outer peripheral surface portion thereof to enter the crack portion, or covers the crack portion and closes the crack portion. By applying the crack plugging material, it is possible to prevent the crack plugging material from melting and plugging the cracking part and entering the inside of the nozzle even if there is a defect in the joint part. It is possible to prevent the structure oxidation in the vicinity of the cracks of the steel, suppress the deterioration of the structure, and prevent the occurrence of steel leakage.

  Further, a crack closing material that softens or melts the outer peripheral surface portion of the molten metal nozzle refractory at a predetermined temperature for use and closes the crack portion has a thickness of 0.005 to 3 mm, preferably 0.1 to 0.5 mm. When cracks due to thermal spalling occur on the outer peripheral surface of the molten metal nozzle refractory, the crack plugging material applied to the outer peripheral surface softens or melts and closes the cracks, and the outside air Even if the inner hole receives a very high temperature molten steel of 1000 ° C. or higher and cracks are generated due to the influence of the thermal spall, the outer peripheral surface portion of the nozzle is suppressed. The crack plugging material applied to the metal melts and penetrates into the crack, or covers the crack and closes the crack, thereby preventing air from being sucked in from the crack and preventing tissue oxidation near the crack of the refractory. , Can also suppress the deterioration of the structure, Raw can also be prevented. As described above, even if there is a problem in installation of joint packing etc., it is possible to prevent the atmosphere from entering the nozzle, as described above, it is possible to prevent tissue oxidation in the vicinity of cracks in the refractory, and to suppress tissue deterioration, The occurrence of steel leakage can also be prevented.

  Furthermore, by applying the crack plugging material to the outer peripheral surface of the nozzle refractory in a thickness of 0.1 to 0.5 mm, the crack plugging material can be easily applied to the nozzle refractory that is cracked by a thermal spall. When applied by spraying, the crack plugging material melts and penetrates into the crack as described above, or covers the crack and closes the crack, and prevents the air from being sucked in from the crack. The nearby structure oxidation can be prevented, the deterioration of the structure can be suppressed, and the occurrence of steel leakage can be prevented.

  The molten metal nozzle refractory and the method of preventing atmospheric suction from the cracked portion of the present invention include a crack plugging material that softens or melts the outer peripheral surface portion of the molten metal nozzle refractory at a predetermined temperature and closes the cracked portion. When a crack due to thermal spalling occurs on the outer peripheral surface of the nozzle refractory, the crack plugging material applied to the outer peripheral surface softens or melts and closes the crack to remove the outside air from the refractory. It is characterized by suppressing suction inside.

  As a refractory for a molten metal nozzle, it can be applied to all refractories used in a place where a molten metal is circulated inside the nozzle, cracks are generated by thermal spalling, and the atmosphere is sucked from the cracked portion. Even if cracks occur in the nozzle refractory, the use of the refractory does not end immediately, but it can be used while being held in a surrounding refractory or a metal case, and the use can be extended. Refractories that suck in the atmosphere include the upper nozzle of the ladle, the sliding plate (upper plate, lower plate), the intermediate nozzle below it, the lower nozzle, the air seal pipe (long nozzle), and between the ladle and the mold. Yes, an upper nozzle, a plate, an intermediate nozzle, a lower nozzle, a squeezing nozzle, and the like that are mounted on a tundish of an intermediate container held by molten steel are applicable.

  These parts are created in a laden atmosphere in the ladle according to the height of the molten steel surface of the tundish, and in the tundish according to the height from the molten steel surface in the mold. Due to deterioration and deterioration of whites of refractory, the use of refractories is significantly limited due to wear.

  A fine space called a joint is formed between each of the upper nozzle, the sliding nozzle, the intermediate nozzle, and the lower nozzle. Therefore, at the time of use, a mortar refractory or a packing refractory having a certain thickness previously formed in a donut shape is installed in the joint, and the actual space is used to fill the gap. Frequently, the refractory wears out abnormally starting from the joint, and drooling occurs where the molten steel inside leaks out of the furnace.

  The molten metal nozzle refractory 1 is replaceably attached to the bottom of a molten metal container such as a ladle or tundish, and the molten metal flows out into a casting apparatus or the like and is injected into a mold or the like. As shown in FIG. 1, an upper nozzle 2, a sliding plate 3, an intermediate nozzle 4, a lower nozzle 5, and the like can be applied. And such a refractory 1 for molten metal nozzles is equipped with sealing materials (not shown) such as mortar and packing at joints 6, 7, 8, and 9 between them, and there is no leakage steel or the like. Are joined together. However, the nozzle inner hole 10 receives a very high-temperature molten steel of 1000 ° C. or more, and the compressive stress is generated in the vicinity of the nozzle inner hole due to the influence of the thermal spall, and the tensile stress is generated in the outer periphery of the nozzle. For example, as shown in FIGS. 2 (a) and 2 (b), cracks 11 and 12 are generated in the outer peripheral portion of the nozzle, and these cracks 11 and 12 expand as the number of times of receiving steel increases. The situation where the outside air is sucked through the cracks 11 and 12 occurs. Cracks also occur in the upper nozzle 2 and the sliding plate 3 part.

  Since the molten steel ladle for steelmaking controls the molten steel flow rate as described above, the upper nozzle 2, the sliding nozzle 3, the intermediate nozzle 4, and the lower nozzle 5 are arranged at the bottom of the molten steel pan. During the casting of the molten steel using the sliding nozzle 3, the molten steel flow path is reduced to the sliding motion of the sliding plate through the inner hole 10 of the sliding nozzle 3, and the flow rate is controlled at a constant flow rate. Under such an environment, the pressure is reduced according to the head pressure of the molten steel according to Bernoulli's law. In particular, in the vicinity of the throttle portion that requires the fitting portion, the intermediate nozzle 4, and the lower nozzle 5, the pressure of the molten steel becomes a negative pressure that is almost near the vacuum with respect to the atmospheric pressure around the sliding nozzle 3.

  In particular, when the nozzle refractory 1 receives a very high temperature molten steel of 1000 ° C. or more in the inner hole 10, a crack is generated due to the effect of the thermal spall, and the crack expands as the number of received steels increases. Eventually reaches the inner hole. When the turtles 11 and 12 reach the nozzle inner hole 10 side, since the inner hole 10 is in a negative pressure atmosphere, there is a possibility of sucking the outside air through the cracks 11 and 12. If the joint refractory is completely installed and the joint refractory is slightly damaged, the air is not sucked, but it is often easy to suck air from the joint portion. When the atmosphere is sucked from the joint portion, the atmosphere, that is, air containing 21% of oxygen enters the crack, and carpon oxidation of the refractory structure near the crack proceeds. Therefore, a crack closing material 13 that melts at a predetermined temperature and penetrates into the cracks 11 and 12 and closes the cracks 11 and 12 is adhered to the outer peripheral surface portion of the nozzle refractory 1, and cracks 11 due to thermal spalling, In order to prevent fragile deterioration of the refractory structure, the outside air is prevented from being sucked into the nozzle inner hole 10 from 12.

  The crack closing material 13 is a joint material 6, 7, 8, 9 or packing material between the upper nozzle 2 and the sliding plate 3, between the sliding plate 3, between the nozzle 4 and the sliding plate 3, and between the nozzles 4 and 5. It can apply | coat over these outer peripheral surface parts of these nozzles and the sliding plate 3 from an outer peripheral part. Further, the crack closing material 13 includes a joint surface between the nozzle 2 and the sliding plate 3, a joint surface between the sliding plate 3, a joint surface between the nozzle 4 and the sliding plate 3, a joint surface between the nozzles 4 and 5, and these. It can also apply | coat over the outer peripheral surface part. In particular, since the cracks 11 and 12 start from the outer corners of the upper and lower ends of the upper nozzle 2, the intermediate nozzle 4, and the lower nozzle 5, these upper end surfaces as shown in FIGS. 2 (a) and 2 (b), It is desirable and important to apply to the outer peripheral surface portion of the lower end surface.

  In the present invention, a crack closing material 13 such as a binder such as a solvent, an upper drug, an antioxidant or the like is applied in advance to the surface portion where the crack of the refractory 1 for nozzles is generated and melted at the use temperature. It is to suppress atmospheric suction from the cracks by forming a liquid phase and closing the surface of the cracked part. The crack plugging material 13 to be applied melts at a temperature castle where the joint portion or the like reaches at the time of use, and not only suppresses atmospheric suction from the crack by covering the crack portion, but also the surface of the refractory by capillary action. It penetrates into the crack which generate | occur | produced in this, It is characterized by closing a crack. Although there are cases where the crack does not penetrate into the crack due to wettability with the melt, the intrusion of air can be prevented by covering the surface of the crack, so that the purpose can also be achieved in that case. Thereby, even if air | atmosphere exists in a joint part etc. from the malfunction of the joint packing installation, it can prevent that air | atmosphere penetrate | invades in a crack.

  The crack closing material 13 is softened or melted in this way to close the crack portion, and it is necessary that the refractory 1 for the nozzle melts when the crack occurs and covers the crack portion or enters and closes. It is. Melts at a cracking temperature of 200 ° C. to 1200 ° C., preferably 300 to 700 ° C. (When cracks enter the outer periphery of the nozzle during actual use, it melts at the outermost temperature of the upper and lower ends of the nozzle. It is possible to use glazes, metal oxides, and ceramic coating materials.

  As the viscosity of the crack closing material 13, a viscosity of about 0.01 cP to 200 P can be applied at the melting temperature as described above. If it is 0.1 cP or less, the viscosity after melting is too low to flow out, and if it is 1000 P or more, it is too viscous and it is difficult to cover or enter the crack. Preferably, the 2cP-700P position with suitable fluidity is desirable.

Further, the crack closing material 13 is composed of a glaze of phosphate glass powder whose main components are Al ₂ O ₃ , P ₂ O ₃ , Na ₂ O, K ₂ O and a softening point of about 400 ° C., and SiO ₂ , Al ₂ O _{3. , B 2 O 3, Na 2} O, K 2 O, glaze or borate glass powder about 500 to 600 ° C. the softening point of _{ZnO, SiO 2, Al 2 O} 3, P 2 O 3, Na 2 O, K 2 A metal oxide such as O or a ceramic coating material can be applied. These glazes and the like may be used by being dispersed in water or a binder as they are, or a binder such as dextrin may be added and used in order to strengthen the adhesion to the nozzle surface.

Crack occluder 13 can be set based on the glaze composition, for example, Al ₂ O ₃ 0.1 to 0.2 the total amount of RO in Zegeru formula 1.0 eq, P ₂ O ₃ 0.1~0 .2, Na ₂ O 0.05-0.2, K ₂ O 0.1-0.2, SiO ₂ 1.0-2.5, Al ₂ O ₃ 0.1-0.5, B ₂ O _{3 0.1~0.2, Na 2 O0.1~0.3, K} 2 O0.1~0.3, predetermined compounding refractory softening such ZnO0.1～0.2, the molten material be able to.

  As the application part of the crack closing material 14, the nozzle refractory 1 covering the metal case 14 exposes the upper end surface and the lower end surface of the nozzle, the outer peripheral surface thereof, and the metal case 14 when not covered. It can apply over the entire outer peripheral surface of the refractory material. When the position where the crack enters can be specified, the amount of the crack closing material 13 to be applied can be reduced and the cost merit can be enjoyed by intensively applying the position where the crack occurs. In addition, as a position where a crack enters, a cut line, a cutout, or the like can be provided in the outer periphery of the nozzle refractory 1 in advance.

  Moreover, as application | coating thickness of the crack closure material 13, it can be set to 5 micrometers-3 mm of 0.005 mm. If it is thinner than 5 μm, it is not sufficient to cover the width of the crack, and if it is thicker than 3 mm, it melts during melting and creates a gap in the fitting portion, which is not preferable. Preferably, the crack portion can be easily closed with a thickness of 0.1 to 0.5 mm, more desirably 0.2 mm. As a method for applying the crack closing material 13, it may be applied in advance at a factory for manufacturing the nozzle refractory 1 or may be applied immediately before use on site. The application method may be a brush application or a spraying method, and a coating that can be easily and uniformly applied is preferable. In addition, it can also be made to pressurize and permeate | transmit the above-mentioned surface part.

  Further, the crack closing material 13 is applied with a reservoir provided between the nozzle refractory 1 and the metal case, or the outer metal case and the refractory so that the melt does not flow out of the nozzle above the nozzle. It is also possible to provide a reservoir such as a circumferential groove that holds the crack closing material 13 between the object and the metal case, the refractory, or both. Further, the crack closing material 13 may be soaked in the packing, and the packing may be installed in close contact with the surface of the refractory.

Table 1 shows examples of the present invention and comparative examples thereof, and the main components are Al ₂ O ₃ , P ₂ O ₃ , Na ₂ O, and K so as to melt at 300 to 700 ° C. as the crack plugging material 13. _Using a glass powder glaze with a composition of ₂ O, adjust by mixing the solvent into a viscous liquid of 2 cP to 700 P, and with a metal case for the ladle as shown in FIGS. 2 (a) and 2 (b). The intermediate nozzle 4 was coated at various thicknesses as shown in the table on the upper surface and the lower surface of the intermediate nozzle 4 and the upper surface and the lower surface of the lower nozzle 5 with a metal case.

  As a result, cracks occurred in the refractories for the nozzles, but none of the examples of the present invention as shown in FIG. 3 had any evidence of air intrusion from the nozzle surface, and the number of uses was extended, The object of the present invention has been achieved. On the other hand, in the conventional comparative example as shown in FIG. 4, the atmosphere enters the cracked portion of the refractory for the nozzle from the nozzle surface and is oxidized. If the surface of the nozzle is covered with the crack plugging material 13, the coating thickness is as thin as 0.06 mm, which has a considerable effect, and preferably about 0.1 to 0.5 mm. I can say that.

Comparative table of examples and comparative examples of the present invention

Diagram for explaining the structure of the refractory for the molten metal nozzle of the present invention, Intermediate nozzle (a) of the refractory for the nozzle same as above, and lower nozzle cross-sectional view (b), Cross-sectional view of the crack state of the intermediate nozzle of the refractory for the nozzle as above, The crack state sectional view of the middle nozzle of the refractory for nozzles of a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Refractory material for molten metal nozzles 10 ... Nozzle inner hole 11, 12 ... Crack 13 ... Crack closure material

Claims (5)

It is a refractory for a molten metal nozzle that flows out molten metal from a molten metal container such as a ladle or tundish,
In order to suppress the outside air from the crack due to thermal spalling from being sucked into the nozzle, the outer periphery of the refractory for the nozzle is softened or melted at a predetermined temperature to close the crack. A refractory for a molten metal nozzle, characterized by applying a material. 0.005 to 3 mm of a crack closing material that softens or melts at a predetermined temperature on the upper surface and / or lower surface of the molten metal nozzle refractory and enters the crack, or covers the crack and closes the crack The refractory for a molten metal nozzle according to claim 1, applied at a thickness of A crack that melts at a predetermined temperature between the nozzles of the refractory for molten metal nozzles, or the joint surface with the sliding plate, and the outer peripheral surface part thereof, enters the crack part, or covers the crack part and closes the crack part. The refractory for a molten metal nozzle according to claim 1, wherein a blocking material is applied. A method for preventing atmospheric suction from a cracked portion of a refractory for a molten metal nozzle that flows out molten metal from a molten metal container such as a ladle or tundish,
A crack closing material that is softened or melted at a predetermined temperature for use on the outer peripheral surface portion of the nozzle refractory to close the crack portion has a thickness of 0.005 to 3 mm, preferably 0.1 to 0.5 mm. Apply,
When a crack due to thermal spalling occurs on the outer peripheral surface of the refractory for the nozzle, the crack plugging material applied to the outer peripheral surface softens or melts to close the crack and sucks outside air into the refractory. A method for preventing atmospheric suction from a crack portion of a refractory for a molten metal nozzle, characterized in that The refractory for a molten metal nozzle according to any one of claims 1 to 3, wherein a crack closing material is applied to the outer peripheral surface portion of the refractory for the nozzle in a thickness of 0.1 to 0.5 mm.