Method for shortening the oxygen injection time of the re-opening of the tundish of a bloom caster

Abstract

The present application belongs to the field of bloom continuous casting, and relates to a method for shortening the oxygen blowing time of a reopened tundish of a bloom continuous casting machine. When an unplanned casting stop occurs, production needs to be resumed urgently, and two tundishes of the casting machine are opened to a baking position, and both tundishes are baked with a large fire simultaneously. An old tundish is pushed into a Φ20m sliding block using an online oil cylinder, and the operation of blowing oxygen to clean the residual steel in the upper nozzle is performed for the next casting flow, until the oxygen pipe is extended into the channel by 460±50mm, the oxygen blowing is stopped, and a Φ15.5 sliding block is pushed in to wait for casting. The present application can effectively control the thickness of the slag layer, preheat the old tundish, and accurately process the steel column in the upper nozzle, thereby reducing the oxygen blowing and drainage time of the tundish reopening process at the casting position, improving the success rate of tundish reopening, and increasing the headroom height at the bottom of the old tundish at the preheating position, which provides a large operation space, is beneficial to blowing oxygen to clean the residual steel in the upper nozzle of the tundish, reduces damage to the upper nozzle caused by improper oxygen blowing, and reduces production safety accidents such as inter-plate steel leakage caused by damage to the upper nozzle.

Description

Technical Field

[0001] This invention belongs to the field of billet continuous casting and relates to a method for shortening the oxygen diversion time of the tundish in a billet continuous casting machine. Background Technology

[0002] Tundish restart refers to the operation of resuming pouring after the tundish is left empty, followed by a second tundish baking, to reduce the time of unplanned pouring interruptions caused by situations such as ladle departure delays, inability to start ladle drainage, or equipment failure. This operation method can flexibly respond to abnormal situations such as ladle departure delays, inability to start ladle drainage, and equipment failure, thereby reducing unplanned pouring interruptions and downtime.

[0003] The following problems exist with the current tundish restart procedure: 1. Unplanned interruptions in casting are unpredictable, making it impossible to execute the tundish restart procedure; 2. When production abnormalities require a second start of casting, before stopping casting, the ladle slide should be fully opened to quickly raise the liquid level in the tundish and perform slag removal. After slag removal, no more tundish covering agent should be added; 3. The steel column inside the old tundish nozzle was not treated during the preheating process, resulting in a long flow time after the old tundish reaches the casting position again, rapid cooling of the molten steel in the tundish, poor fluidity, and a high failure rate. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a method for shortening the oxygen priming time in the tundish re-opening process of a billet continuous casting machine. This method can effectively control the slag layer thickness, preheat the old tundish while treating the steel column inside the water inlet, thereby reducing the oxygen priming time at the casting position during the tundish re-opening process, improving the success rate of tundish re-opening, and reducing production safety accidents.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for shortening the oxygen diversion time in the tundish of a billet continuous casting machine, comprising the following steps:

[0006] S1, the slag thickness in the intermediate ladle of the continuous casting furnace shall be controlled to be <100mm;

[0007] S2, if an abnormality occurs, immediately close the ladle slide plate, and pour molten steel into the tundish as needed. When the remaining water in the tundish is less than 150mm, gradually cut off the flow from both sides to the middle, and use the intermediate flow to pour out as much remaining water as possible in the tundish. No slag should be poured into the tundish.

[0008] S3, move the two tundishes of the casting machine to the baking position, and bake the two tundishes at the same time with high heat; use the online hydraulic cylinder to push in the Φ20mm slider of the old tundish, and perform oxygen burning to clean the residual steel in the water inlet for the first pouring flow until the oxygen pipe extends into the channel 460±50mm, stop oxygen burning, push in the Φ15.5mm slider and wait for the pouring to start.

[0009] S4. After the tail billet is finished, immediately send the siphon ingot to prepare for the next casting. The tail billet is treated in the same way as the normal interrupted casting tail billet treatment.

[0010] S5, bake the old intermediate bread at 1100-1300℃ for less than 1 hour;

[0011] S6, the first furnace restarted, the molten steel exiting the station at a temperature 20-30℃ higher than the normal start-up temperature;

[0012] S7. After the main ladle starts pouring, the liquid level in the tundish must be >350mm and the tundish scale weight must be >14t before the tundish can be used to start pouring.

[0013] S8, the tundish adopts two-stream simultaneous casting. The initial casting is carried out in the order of N2, N5→N3, N4→N1, N6. The initial casting speed is 1.5-1.6m / min. After successful casting, the casting is opened. During the process, protective slag is added frequently but in small amounts to facilitate observation of the liquid level in the crystallizer. The slag discharge situation in the tundish is closely observed. If slag discharge is found, the flow is immediately stopped.

[0014] After S9 is in normal operation, it enters the automatic pouring mode and installs the immersion nozzle. The slider size is changed according to the temperature and rhythm. Subsequently, the intermediate batch is changed according to the baking temperature of the new intermediate batch.

[0015] The beneficial effects of this invention are as follows: This invention can effectively control the slag layer thickness, and accurately treat the steel column inside the water inlet while preheating the old tundish, thereby reducing the oxygen flow time at the casting position during the tundish reopening process, improving the success rate of tundish reopening. At the same time, the old tundish has a high net height at the bottom of the preheating position and a large operating space, which is conducive to oxygen cleaning of residual steel inside the tundish water inlet, reducing damage to the water inlet caused by improper oxygen burning, and reducing production safety accidents such as steel seepage between plates caused by damage to the water inlet.

[0016] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Detailed Implementation

[0017] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0018] This invention discloses a method for shortening the oxygen diversion time in the tundish of a billet continuous casting machine, comprising the following steps:

[0019] S1, the slag thickness in the intermediate ladle of the continuous casting furnace shall be controlled to be <100mm;

[0020] S2, if an abnormality occurs, immediately close the ladle slide plate, and pour molten steel into the tundish as needed. When the remaining water in the tundish is less than 150mm, gradually cut off the flow from both sides to the middle, and use the intermediate flow to pour out as much remaining water as possible in the tundish. No slag should be poured into the tundish.

[0021] S3, move the two tundishes of the casting machine to the baking position, and bake the two tundishes at the same time with high heat; use the online hydraulic cylinder to push in the Φ20mm slider of the old tundish, and perform oxygen burning to clean the residual steel in the water inlet for the first pouring flow until the oxygen pipe extends into the channel 460±50mm, stop oxygen burning, push in the Φ15.5mm slider and wait for the pouring to start.

[0022] S4. After the tail billet is finished, immediately send the siphon ingot to prepare for the next casting. The tail billet is treated in the same way as the normal interrupted casting tail billet treatment.

[0023] S5, bake the old intermediate bread at 1100-1300℃ (200℃ higher than normal start-up temperature), baking time <1 hour;

[0024] S6, the first furnace restarted, the molten steel exiting the station at a temperature 20-30℃ higher than the normal start-up temperature;

[0025] S7, after the main ladle starts casting, the liquid level in the tundish must be >350mm and the tundish weight must be >14t before the tundish can be used for initial casting (50-100mm higher than normal casting).

[0026] S8, the tundish adopts two-stream simultaneous casting. The initial casting is carried out in the order of N2, N5→N3, N4→N1, N6. The initial casting speed is 1.5-1.6m / min. After successful casting, the casting is opened. During the process, protective slag is added frequently but in small amounts to facilitate observation of the liquid level in the crystallizer. The slag discharge situation in the tundish is closely observed. If slag discharge is found, the flow is immediately stopped.

[0027] After S9 is in normal operation, it enters the automatic pouring mode and installs the immersion nozzle. The slider size is changed according to the temperature and rhythm. Subsequently, the intermediate batch is changed according to the baking temperature of the new intermediate batch.

[0028] This invention controls the slag thickness in the tundish during daily continuous casting cycles. A probe is used to check the slag thickness inside the tundish (if it exceeds the limit, the ladle slide is fully opened, the slag level is quickly raised, and slag removal is performed). The slag layer thickness is ≤100mm, ensuring the tundish can be reopened at any time. When an unplanned interruption of casting occurs, production needs to be resumed urgently. Both tundishes are opened to the baking position, and both are simultaneously baked at high heat. For the old tundish, an online hydraulic cylinder pushes in a Φ20mm slider to perform oxygen cleaning of the residual steel in the inlet for the first casting cycle, until the oxygen pipe extends 460±50mm into the channel. Oxygen is then stopped, and a Φ15.5mm slider is pushed in to await the start of casting.

[0029] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for shortening the oxygen diversion time in the tundish of a billet continuous casting machine, characterized in that, Includes the following steps: S1, the slag thickness in the intermediate ladle of the continuous casting furnace shall be controlled to be <100mm; S2. If an abnormality occurs, immediately close the ladle slide plate and pour molten steel into the tundish as needed. When the remaining water in the tundish is less than 150mm, gradually cut off the flow from both sides to the middle. Use the intermediate flow to pour out as much remaining water as possible from the tundish, and do not pour slag into the tundish. S3, move the two tundishes of the casting machine to the baking position, and bake the two tundishes at the same time with high heat; use the online hydraulic cylinder to push in the Φ20mm slider of the old tundish, and perform oxygen burning to clean the residual steel in the water inlet for the first pouring flow until the oxygen pipe extends into the channel 460±50mm, stop oxygen burning, push in the Φ15.5mm slider and wait for the pouring to start. S4. After the tail billet is finished, immediately send the siphon ingot to prepare for the next casting. The tail billet is treated in the same way as the normal interrupted casting tail billet treatment. S5, bake the old intermediate bread at 1100-1300℃ for less than 1 hour; S6, the first furnace restarted, the molten steel exiting the station at a temperature 20-30℃ higher than the normal start-up temperature; S7. After the main ladle starts pouring, the liquid level in the tundish must be >350mm and the tundish scale weight must be >14t before the tundish can be used to start pouring. S8, the tundish adopts two-stream simultaneous casting. The initial casting is carried out in the order of N2, N5→N3, N4→N1, N6. The initial casting speed is 1.5-1.6m / min. After successful casting, the casting is opened. During the process, protective slag is added frequently but in small amounts to facilitate observation of the liquid level in the crystallizer. The slag discharge situation in the tundish is closely observed. If slag discharge is found, the flow is immediately stopped. After S9 is in normal operation, it enters the automatic pouring mode and installs the immersion nozzle. The slider size is changed according to the temperature and rhythm. Subsequently, the intermediate batch is changed according to the baking temperature of the new intermediate batch.