Method for increasing the life of a slab continuous casting tundish

Abstract

The embodiment of the application provides a method for prolonging the service life of a slab continuous casting tundish, which comprises the following steps: centering a tundish baking hole with a burner and pressing up a stopper, then igniting the burner, and pouring steel after performing stage baking on the tundish, wherein the stage baking comprises small fire baking, medium fire baking, large fire baking and heat preservation. The tundish is baked in stages, the tundish baking temperature curve is reasonably controlled, the tundish temperature is controlled in the target baking temperature range of the tundish starting pouring, the service life of the tundish is prolonged, the upper limit of the continuous casting is increased, the continuous casting time is prolonged, the number of tundishes used is effectively reduced, and the production cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of metallurgical continuous casting technology, and more specifically, to a method for improving the life of the tundish in slab continuous casting. Background Technology

[0002] The tundish is one of the key pieces of equipment in the continuous casting process, playing a crucial role in connecting the preceding and following stages. It distributes molten steel into different crystallizers and provides functions such as stabilizing and distributing the molten steel flow. It also serves as a refining empty container. Through tundish metallurgy, secondary oxidation and gas absorption of molten steel can be prevented, the flow state of molten steel can be improved, slag entrapment can be prevented, inclusions can be promoted to float, the composition of molten steel can be finely adjusted, the morphology of inclusions can be controlled, and the superheat of molten steel can be precisely controlled. It plays an important role in ensuring smooth continuous casting operation, increasing the continuous casting rate, enabling multiple furnaces to be cast consecutively, expanding the variety of continuous castings, and improving the quality of cast billets.

[0003] Currently, the lifespan of tundishes in slab continuous casting is generally around ten hours, making it difficult to reach the designed lifespan of over 25 hours. The short tundish lifespan results in fewer continuous casting furnaces, higher continuous production costs, greater tundish consumption, and discontinuous production, which can easily lead to the squeezing of molten iron and affect the production rhythm of the entire steel plant. Summary of the Invention

[0004] The objectives of this invention include, for example, providing a method for improving the lifespan of the tundish in slab continuous casting, which can improve the efficiency of converter and continuous casting production, reduce the cost of tundish use, and meet the production needs of converter and continuous casting.

[0005] The embodiments of the present invention can be implemented as follows:

[0006] In a first aspect, the present invention provides a method for improving the life of a tundish in slab continuous casting, comprising aligning the tundish baking hole with the burner and pressing up the stopper rod, then igniting the burner, performing staged baking on the tundish before casting steel, wherein the staged baking includes low-heat baking, medium-heat baking, high-heat baking, and heat preservation:

[0007] During the low-fire baking, the air valve opening is 40-45%, the gas valve opening is 45-50%, the flame touches the bottom of the tundish, and the baking time is greater than 60 minutes until the working layer temperature of the tundish reaches 400-600℃.

[0008] During the intermediate heating process, the air valve opening is 50-60%, the gas valve opening is 50-55%, the blue flame overflows the tundish cover by 450-550mm, and the heating is carried out until the working layer temperature of the tundish reaches 800-900℃.

[0009] During the high-fire baking, the air valve opening is 60-70%, the gas valve opening is 55-60%, the blue flames overflow the cover by 250-350mm, and the baking time is greater than 60min until the temperature of the intermediate ladle working layer is ≤1200℃.

[0010] During the heat preservation process, the air valve opening is 50-60%, the gas valve opening is 50-55%, the flame touches the bottom of the tundish, and the tundish is kept warm for more than 30 minutes to maintain the working layer temperature of the tundish at 1000-1150℃.

[0011] In an optional implementation, the total duration of baking over low heat, baking over medium heat, baking over high heat, and heat preservation is 2.5-4.0 hours.

[0012] In an optional embodiment, the process also includes baking the entire sprue, wherein the baking time is 60-150 minutes and the sprue is baked to 800-1100°C.

[0013] In an optional implementation, when the total duration of the low-heat baking, medium-heat baking, high-heat baking and heat preservation is 2-2.5 hours, the temperature of the molten steel in the tundish is more than 10°C higher than the preset pouring temperature.

[0014] In an optional implementation, after the staged baking is completed, the temperature of the stopper head is ≥1100℃.

[0015] In an optional embodiment, the minimum liquid level height during steel pouring in the tundish is greater than 300mm, the normal target weight for pouring in the tundish is 25-30t, and the pouring volume in the sub-bundle is ≥15t.

[0016] In an optional implementation, when the liquid slag thickness is ≥100mm, tundish slag discharge is performed.

[0017] In an optional embodiment, the fabrication of the intermediate package includes the fabrication of a working layer, which includes: placing a fetal membrane within the permanent layer of the intermediate package, placing positioning steel strips between the fetal membrane and the permanent layer, placing the positioning steel strips around the fetal membrane to position the fetal membrane, and then filling the space between the fetal membrane and the permanent layer with working layer material to form a working layer.

[0018] In an optional embodiment, the positioning steel strip is vertically positioned between the tundish and the permanent layer. The positioning steel strip includes a base material and an adjusting plate. The adjusting plate is detachably mounted on the base material by means of an internal hex screw. By selecting different numbers of adjusting plates, the thickness of the positioning steel strip can be adjusted to adapt to different specifications of tire films, thereby obtaining working layers of different thicknesses.

[0019] In an optional embodiment, the thickness of the intermediate packing working layer is: 30-50mm for the upper part of the packing wall, 40mm±5mm for the middle and lower part of the packing wall, and 50±5mm for the bottom of the packing wall; the thickness of the permanent layer is greater than 150mm.

[0020] The beneficial effects of the embodiments of the present invention include, for example:

[0021] The intermediate tundish is baked in stages, and the baking temperature curve of the intermediate tundish is reasonably controlled. The temperature of the intermediate tundish is kept within the target baking temperature range for the start of pouring, which extends the service life of the intermediate tundish, increases the upper limit of the number of consecutive pours and the duration of consecutive pouring, effectively reduces the number of intermediate tundishes used, and reduces production costs. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the structure used when steel bars are used to position the tire membrane.

[0024] Figure 2 This is a structural diagram of the positioning steel bar.

[0025] Icons: 100-Intermediate layer; 110-Permanent layer; 120-Working layer; 130-Fetal membrane; 140-Positioning steel strip; 141-Base material; 142-Adjusting plate. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0028] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0029] In the description of this invention, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed, they are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0030] Furthermore, the terms "first" and "second" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0031] It should be noted that, where there is no conflict, the features in the embodiments of the present invention can be combined with each other.

[0032] This embodiment provides a method for improving the service life of the tundish 100 in slab continuous casting, including aligning the baking hole of the tundish 100 with the burner and pressing up the stopper rod, then igniting the burner, performing staged baking on the tundish 100 before casting steel. The staged baking includes low-heat baking, medium-heat baking, high-heat baking, and heat preservation.

[0033] During the low-fire baking, the air valve opening is 40-45%, the gas valve opening is 45-50%, the flame touches the bottom of the tundish 100, and the baking time is greater than 60 minutes until the temperature of the working layer 120 of the tundish 100 reaches 400-600℃.

[0034] During the medium-fire baking, the air valve opening is 50-60%, the gas valve opening is 50-55%, the blue flame overflows the cover by 450-550mm, and the baking is carried out until the temperature of the intermediate ladle 100 working layer 120 is 800-900℃.

[0035] During the high-fire baking, the air valve opening is 60-70%, the gas valve opening is 55-60%, the blue flames overflow the cover by 250-350mm, and the baking time is greater than 60min until the temperature of the intermediate layer 100 working layer 120 is ≤1200℃.

[0036] During the heat preservation process, the air valve opening is 50-60%, the gas valve opening is 50-55%, the flame touches the bottom of the tundish 100, and the tundish 100 is kept warm for more than 30 minutes to maintain the working layer 120 temperature of the tundish 100 at 1000-1150℃.

[0037] This embodiment employs staged baking, optimizing the gas and compressed air opening to rationally control the baking temperature curve of the tundish 100, keeping the tundish 100 temperature within the target baking temperature range for pouring, thus avoiding problems such as excessively short or long baking time or uneven baking temperature. In this embodiment, baking is carried out with a low flame until the working layer 120 of the tundish 100 reaches a temperature of 400-600℃, and the baking temperature of the tundish 100 does not exceed 1200℃. The target baking temperature for pouring of the tundish 100 is controlled at 1000~1150℃ (the temperature of the stopper rod area is measured with a flame before pouring). Specifically:

[0038] Before baking, visually confirm that the alignment deviation between the baking hole of the intermediate ladle 100 and the burner is ≤50mm. Use a wooden dowel to press up the stopper rod. The stopper rod must be pressed up throughout the baking process of the intermediate ladle 100. When the intermediate ladle 100 is opened to the pouring position and ready to start pouring, press the handle twice before putting down the stopper rod.

[0039] Ignite the burner. After the burner is lit, lower the oven to ensure the gap between the lid and the stopper is ≥30mm. Using the "low heat" control standard, maintain the baking temperature at 400-600℃ after 1 hour of "low heat". Using the "medium / high heat" control standard, maintain the baking temperature at 800-900℃ after 1 hour of "medium heat" and at 1000-1150℃ after 1 hour of "high heat". The "low heat" and "high heat" times must be at least 60 minutes, while the "medium heat" and "holding time" can be adjusted according to the baking situation. Specifically, the oven opening requirements and baking times are shown in Tables 1 and 2.

[0040] Table 1. Oven Opening Requirements

[0041]

[0042] Table 2 Baking Time Requirements

[0043]

[0044] When the intermediate ladle reaches the pouring position at 100°, lower the stopper rod and confirm that the stroke has returned to the correct position (to prevent sticking during baking, the rod must be pressed up throughout the baking process and the process can only be cancelled when the intermediate ladle reaches the pouring position at 100°).

[0045] It should be noted that during the installation of the long sleeve in the ladle, the inclination angle of the sleeve can be manually controlled, preferably tilted 5-10° in the opposite direction to the outer wall of the impact zone. This shifts the flow field vortex in the impact zone to the central area of ​​the tundish 100, preventing erosion. Additionally, maintaining a stable temperature during the ladle process and ensuring the temperature of the molten steel reaching the continuous casting platform is appropriate are crucial. Excessive overheating of the molten steel should be avoided to prevent erosion of the tundish 100 lining, while also preventing damage to the tundish 100 lining caused by oxygen permeation and heating due to excessively low molten steel temperature.

[0046] In an optional implementation, the total time for baking over low heat, baking over medium heat, baking over high heat, and heat preservation is 2.5-4.0 hours.

[0047] Baking time less than or greater than "2.5-4.0h" is considered abnormal baking. Specifically:

[0048] "Minimum Abnormal Time" refers to the shortest baking time allowed in tundish 100 under abnormal production conditions. It is mainly achieved by canceling or reducing "medium fire time" and "holding time". Too short a total baking time will lead to insufficient venting of tundish 100, resulting in collapse of working layer 120 and bubbles in the billet. Incomplete baking of tundish 100 will cause steel to form on the opening of the pouring plug and large flow at the nozzle due to temperature drop of molten steel. Excessive baking temperature rise will cause refractory materials such as slag retaining walls to crack.

[0049] Abnormal baking with a total baking time greater than the "total time" but less than 13 hours can be reduced to medium heat (maintaining the temperature) if the high heat control has already been activated. When the baking of the intermediate roll 100 has reached the upper limit of the target baking temperature, the high heat baking stage should be cancelled. Excessive total baking time will lead to over-baking of the intermediate roll 100 (temperature ≥1200℃, long baking time), resulting in oxidation and melting of the stopper rod, melting, deformation and loosening of the stopper rod core and cross arm, melting, deformation and refractory detachment of the roll cover steel structure, collapse of the working layer 120, and adhesion of the stopper rod head to the upper gate cup, etc.

[0050] "Maximum Abnormal Time" refers to the longest allowable baking time for the tundish 100 under abnormal production conditions, which is 13 hours. This is mainly achieved by extending the medium and low heat times. If the total baking time is too long, the tundish 100 will be unable to be poured after baking, and the service life of the refractory material will be reduced. If the medium heat control has been activated, it is not allowed to be reduced to low heat (the baking temperature must be maintained at no less than 900℃ to prevent the working layer 120 of the tundish 100 from cracking and collapsing due to cooling).

[0051] 100 intermediate loaves with a total baking time exceeding 13 hours are scrapped and not used.

[0052] In an optional embodiment, the process also includes baking the entire sprue, wherein the baking time is 60-150 minutes and the sprue is baked to 800-1100°C.

[0053] In the overall control of sprue baking, baking time and temperature that are too low may cause the sprue to crack; baking time and temperature that are too high may cause oxidation and decarburization of aluminum-carbon or zirconium-carbon sprues, resulting in reduced strength and lifespan. Each baking cycle should be checked to confirm the baking effect of the baking machine, whether the gas pressure is normal, whether the baking is uniform, and whether the temperature difference between the two sides is small.

[0054] In an optional implementation, when the total duration of the low-heat baking, medium-heat baking, high-heat baking and heat preservation is 2-2.5 hours, the temperature of the molten steel in the tundish 100 is more than 10°C higher than the preset pouring temperature.

[0055] For the intermediate ladle with a shorter total baking time (100), the lower limit temperature of the first heat of molten steel in the large and medium ladles is more than 10°C higher than the normal first heat pouring temperature, i.e., the pouring temperature is 1010-1150°C.

[0056] In an optional implementation, after the staged baking is completed, the temperature of the stopper head is ≥1100℃.

[0057] In an optional implementation, the minimum liquid level height during steel pouring in the tundish 100 is greater than 300mm, the normal target weight for pouring in the tundish 100 is 25-30t, and the amount poured in the sub-bundle is ≥15t.

[0058] The seamless connection of molten steel between the converter and continuous casting is essential for ensuring normal continuous casting production. This requires timely supply of molten steel to continuous casting, a proper match between converter and continuous casting production volumes, enhanced information transmission for production scheduling, and rational production organization to ensure a stable molten steel level in the tundish (100mm ladle). This prevents excessive fluctuations in the molten steel level caused by untimely continuous casting, which could damage the tundish lining. Maintaining the molten steel level in the tundish (100mm ladle) within the required range is crucial for ensuring its service life.

[0059] Maintaining a high liquid level in the tundish 100 is crucial for ensuring normal slab casting and reducing the risk of slag entrapment caused by excessively low molten steel levels. If the tundish 100 liquid level is low (e.g., 200mm), non-metallic inclusions in the molten steel are higher, and the lining is prone to cracking. A liquid level greater than 300mm, with a normal casting target weight of 25-30t and a transfer casting volume ≥15t, prolongs the molten steel's dwell time in the tundish 100, allowing non-metallic inclusions to rise and improving steel quality. Furthermore, it prevents a rapid drop in the tundish lining temperature due to a low liquid level, which, in turn, causes a rapid rise in the working layer 120 temperature after casting begins, potentially leading to cracking of the tundish lining (primarily the working layer 120).

[0060] In an optional implementation, when the liquid slag thickness is ≥100mm, the intermediate ladle 100 slag discharge operation is performed.

[0061] As the number of consecutive heats in the tundish increases, the large amount of slag inside the tundish and the inability to remove it in time lead to severe erosion of the ladle lining by the slag line, which also affects the quality of the molten steel. The slag layer thickness in the tundish is measured every 5 heats (5th, 10th, 15th…). When the slag thickness under the ladle at the tapping point of the tundish 100 reaches ≥100mm, slag removal is mandatory to prevent severe erosion of the ladle wall by the slag line and subsequent steel penetration. Simultaneously, ladle operators must strengthen their operations, controlling the excess steel in the ladle while avoiding placing large amounts of slag into the tundish 100, which would cause severe erosion of the ladle wall by the slag line.

[0062] In an optional embodiment, the fabrication of the intermediate package 100 includes the fabrication of a working layer 120. The fabrication of the working layer 120 includes: placing a membrane 130 within the permanent layer 110 of the intermediate package 100; placing positioning steel strips 140 between the membrane 130 and the permanent layer 110; positioning steel strips 140 are placed around the membrane 130 to position it; and then filling the space between the membrane 130 and the permanent layer 110 with working layer 120 material to form the working layer 120. Specifically, as follows... Figure 1 As shown, the intermediate ladle 100 is made using positioning steel bars 140, and the working layer 120 of the intermediate ladle 100 has a uniform thickness.

[0063] In an optional embodiment, the positioning steel strip 140 is vertically disposed between the tundish 100 and the permanent layer 110. The positioning steel strip 140 includes a base material 141 and an adjusting piece 142. The adjusting piece 142 is detachably mounted on the base material 141 by means of an internal hexagonal screw. The specific structure is as follows: Figure 2 As shown, by selecting different numbers of adjusting pieces 142, the thickness of the positioning steel strip 140 can be adjusted, thereby adapting to different specifications of tire membranes 130 and obtaining working layers 120 of different thicknesses.

[0064] In an optional embodiment, the thickness of the intermediate pack 100 working layer 120 is: 30-50mm for the upper part of the packing wall, 40mm±5mm for the middle and lower part of the packing wall, and 50±5mm for the bottom of the packing wall; the thickness of the permanent layer 110 is greater than 150mm.

[0065] After the intermediate package 100 is prepared, it is inspected and accepted. The inspection procedure for the intermediate package is as follows:

[0066] (1) Acceptance of intermediate package 100 working layer 120

[0067] ① The masonry should be flat, without obvious depressions or protrusions.

[0068] ② The internal cavity dimensions are reasonably controlled to meet the requirements of the package capacity.

[0069] ③ The interior of the liner is clean, with no residual refractory material or steel slag, and the liner has not collapsed.

[0070] ④ The thickness of the working layer 120 is controlled as follows: 30-50mm for the upper part of the wall, 40mm±5mm for the middle and lower parts, and 50±5mm for the bottom, to ensure the quality of the refractory material at the slag line.

[0071] (2) Acceptance of intermediate package 100 permanent layer 110

[0072] ① The lining is intact, with no obvious defects or cracks, and the crack width is <20mm.

[0073] ②The thickness of the permanent layer 110 shall not be less than 150mm.

[0074] ③ The area of ​​a single repair in the middle and lower part shall not exceed 20×20cm2, and the total area shall not exceed 80×80cm2.

[0075] The procedure for verifying red envelopes is as follows:

[0076] (1) Check the baking effect of intermediate bread 100 every hour of baking.

[0077] ①Measure the baking temperature of the intermediate bread at 100°C and track the baking effect.

[0078] ② Visual inspection of the positive slip difference of the release and pressure rod is 0-3mm: the effective stroke of the mechanism is 35-40mm. Visual inspection shows that there are no obvious cracks or defects in the body of the stopper rod; the bolts for securing the stopper rod and the cross arm are not loose; the pressure rod is tested twice to confirm that there is no obvious jamming in the mechanism; confirm whether the water inlet is blocked: use an oxygen tube or a slag removal rod to insert into the water inlet to confirm that there are no foreign objects inside the water inlet.

[0079] ③ Measure the temperature of the tundish 100 with a flame 15 minutes before pouring. The temperature measurement positions of the tundish 100 are: the stopper rod holes on the east and west sides. (The minimum temperature in the stopper rod area is ≥1000℃).

[0080] ④ During the inspection and maintenance of the packaging and baking equipment, it is forbidden to step on or collide with the stopper rod, water inlet, or stopper rod control mechanism.

[0081] It should be noted that the tundish 100 of continuous casting can adopt the structure of slag retaining wall and slag retaining dam, so that the molten steel flows reasonably in the tundish 100, which is conducive to the floating of non-metallic inclusions in the molten steel, thus improving the quality of the molten steel. On the other hand, it also increases the service life of the tundish 100.

[0082] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0083] Example 1

[0084] This embodiment provides a method for improving the service life of a tundish 100 for slab continuous casting. The method includes aligning the baking hole of the tundish 100 with the burner and pressing up the stopper rod, then igniting the burner to perform staged baking of the tundish 100 before casting steel. The staged baking includes low-heat baking, medium-heat baking, high-heat baking, and heat preservation. During low-heat baking, the air valve opening is 40%, the gas valve opening is 45%, the flame touches the bottom of the tundish 100, the baking time is 60 minutes, and the working layer 120 of the tundish 100 reaches a temperature of 450°C.

[0085] During the medium-fire baking, the air valve opening is 50%, the gas valve opening is 55%, the blue flame overflows the cover by 500mm, the baking time is 60min, the intermediate ladle is 100, the working layer is 120, and the temperature is 850℃.

[0086] During the high-fire baking, the air valve opening is 65%, the gas valve opening is 60%, the blue flame overflows the cover by 300mm, and the baking time is 60 minutes, with the intermediate ladle at 100°C, the working layer at 120°C, and the temperature at 1100°C.

[0087] During the heat preservation process, the air valve is opened to 55%, the gas valve is opened to 50%, the flame touches the bottom of the tundish 100, and the tundish 100 is kept warm for 30 minutes, with the working layer 120 of the tundish 100 reaching a temperature of 1125℃.

[0088] The baking time for the entire sprue is 65 minutes, and the sprue is baked to 865°C.

[0089] After the staged baking is completed, the temperature of the stopper head is 1100℃;

[0090] The minimum liquid level height during steel pouring in the tundish 100 is greater than 300mm. The normal target weight for pouring in the tundish 100 is 25-30t, and the pouring volume in the sub-ladle is ≥15t.

[0091] The thickness of the intermediate layer 100 working layer 120 is: 50mm at the top of the wall, 45mm at the middle and lower part of the wall, and 55mm at the bottom; the thickness of the permanent layer 110 is 180mm.

[0092] The control method for improving the lifespan of the tundish 100 in this embodiment can extend the lifespan of the tundish 100, with a maximum continuous casting capacity of 33 heats. This increases the lifespan of a single tundish 100 from more than 10 hours to more than 30 hours, effectively reducing the number of tundishes used and lowering production costs.

[0093] Comparative Example 1

[0094] The baking process of the tundish 100 in this comparative example 1 for slab continuous casting includes aligning the baking hole of the tundish 100 with the burner, then lighting the burner, and performing staged baking of the tundish 100 before casting steel. The staged baking includes low-heat baking, medium-heat baking, and high-heat baking. During the low-heat baking, the air valve opening is 0%, the gas valve opening is 55%, the flame touches the bottom of the tundish 100, the baking time is 90 minutes, and the working layer 120 of the tundish 100 is 600℃.

[0095] During the medium-fire baking, the air valve opening is 60%, the gas valve opening is 70%, the blue flame overflows the cover by 300mm, the baking time is 120min, the intermediate ladle is 100, the working layer is 120, and the temperature is 1208℃.

[0096] During the high-fire baking, the air valve is opened to 80%, the gas valve is opened to 90%, the blue flames overflow the cover by 200mm, the baking time is 120min, the intermediate layer is 100, the working layer is 120, and the temperature is 1220℃.

[0097] After the staged baking is completed, the temperature of the stopper head is 1220℃;

[0098] The minimum liquid level height during steel pouring in the tundish 100 is greater than 200mm. The normal target weight for pouring in the tundish 100 is 15-30t, and the pouring volume in the sub-ladle is ≥10t.

[0099] The thickness of the intermediate packing 100 working layer 120 is: 30mm at the top of the packing wall, 35mm at the middle and lower part of the packing wall, and 40mm at the bottom of the packing wall; the thickness of the permanent layer 110 is 135mm.

[0100] In Comparative Example 1, the tundish 100 for slab continuous casting has a maximum continuous casting capacity of only 11 heats, and the lifespan of a single tundish 100 is only 10 hours.

[0101] Comparative Example 2

[0102] The only differences between this comparative example and Example 1 are: the air valve opening ratio and the gas valve opening ratio are mismatched; the medium and high heat baking times are long; the tundish baking time requires 5.5 hours; the long tundish baking time, when the baking temperature is ≥1200℃, causes oxidation and melting of the stopper rod, melting, deformation and loosening of the stopper rod core and cross arm, melting, deformation and refractory detachment of the tundish cover steel structure, collapse of the working layer, and adhesion of the stopper rod head to the upper nozzle bowl, etc. In this comparative example 1, the tundish 100 for slab continuous casting has a maximum continuous casting capacity of only 11 heats, and the life of a single tundish 100 is only 10 hours.

[0103] Comparative Example 2

[0104] The only difference between this comparative example and Example 1 is that the overall nozzle baking time in Comparative Example 2 is 180 minutes, and the nozzle temperature is 1168°C. When the baking time and temperature are too high, the aluminum-carbon or zirconium-carbon nozzles will oxidize and decarburize, resulting in reduced strength and lifespan, which will affect the overall lifespan of the tundish. In Comparative Example 1, the tundish 100 for slab continuous casting has a maximum continuous casting capacity of only 11 heats, and the lifespan of a single tundish 100 is only 10 hours.

[0105] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method of improving the life of a slab continuous casting tundish, characterized by, The process includes aligning the tundish baking hole with the burner and pressing up the stopper rod, then igniting the burner to perform staged baking of the tundish before casting the steel. The staged baking includes low-heat baking, medium-heat baking, high-heat baking, and heat preservation. During the low-fire baking, the air valve opening is 40-45%, the gas valve opening is 45-50%, the flame touches the bottom of the tundish, and the baking time is greater than 60 minutes until the working layer temperature of the tundish is 400-600℃. During the intermediate heating process, the air valve opening is 50-60%, the gas valve opening is 50-55%, the blue flame overflows the tundish cover by 450-550mm, and the heating is carried out until the working layer temperature of the tundish reaches 800-900℃. During the high-fire baking, the air valve opening is 60-70%, the gas valve opening is 55-60%, the blue flames overflow the cover by 250-350mm, and the baking time is greater than 60min until the temperature of the intermediate ladle working layer is ≤1200℃. During the heat preservation process, the air valve opening is 50-60%, the gas valve opening is 50-55%, the flame touches the bottom of the tundish, and the tundish is kept warm for more than 30 minutes to maintain the working layer temperature of the tundish at 1000-1150℃. The heat preservation process also includes baking the entire sprue, which takes 60-150 minutes and is baked to 800-1100℃. The total time for baking over low heat, medium heat, high heat, and heat preservation is 2.5-4.0 hours; after the staged baking is completed, the temperature of the stopper head is ≥1100℃. The minimum liquid level height during steel pouring in the tundish is greater than 300mm, the normal target weight for tundish pouring is 25-30t, and the pouring volume in the sub-bundle is ≥15t.

2. The method for improving the life of the tundish in slab continuous casting according to claim 1, characterized in that, When the total duration of baking with low heat, medium heat, high heat and heat preservation is 2-2.5 hours, the temperature of molten steel in the tundish is more than 10°C higher than the preset pouring temperature.

3. The method for improving the life of the tundish in slab continuous casting according to claim 1, characterized in that, When the thickness of liquid slag in the tundish is ≥100mm, the tundish slag discharge operation shall be performed.

4. The method for improving the life of the tundish in slab continuous casting according to claim 1, characterized in that, The fabrication of the intermediate package includes the fabrication of a working layer, which includes: placing a fetal membrane inside the permanent layer of the intermediate package, placing positioning steel strips between the fetal membrane and the permanent layer, placing the positioning steel strips around the fetal membrane to position the fetal membrane, and then filling the space between the fetal membrane and the permanent layer with working layer material to form the working layer.

5. The method for improving the life of the tundish in slab continuous casting according to claim 4, characterized in that, The positioning steel strip is vertically positioned between the intermediate layer and the permanent layer. The positioning steel strip includes a base material and an adjusting plate. The adjusting plate is detachably mounted on the base material by means of an internal hex screw. By selecting different numbers of adjusting plates, the thickness of the positioning steel strip can be adjusted to adapt to different specifications of tire films, thereby obtaining working layers of different thicknesses.

6. The method for improving the life of the tundish in slab continuous casting according to claim 4, characterized in that, The thickness of the intermediate working layer is as follows: 30-50mm for the upper part of the wall, 40mm±5mm for the middle and lower part of the wall, and 50±5mm for the bottom; the thickness of the permanent layer is greater than 150mm.

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