A method for preventing slag from falling during secondary tapping

Abstract

The present application belongs to the field of steelmaking continuous casting, and relates to a method for preventing slag from falling during secondary tapping, reducing the temperature of the slag, changing the liquid slag into semi-molten slag, and effectively avoiding the slag from being rolled into the tapping hole and entering the ladle during secondary tapping. The present application reduces the high phosphorus content of the slag caused by secondary tapping, reduces the influence of the slag on the alloy yield caused by secondary tapping, eliminates the negative influence of secondary tapping when the molten steel is not completely tapped due to operation errors or other reasons, saves the composition out-of-specification caused by the incomplete tapping of the molten steel, and eliminates the influence of the incomplete tapping of the molten steel on the slag splashing and furnace protection.

Description

Technical Field

[0001] This invention belongs to the field of steelmaking continuous casting and relates to a method for preventing slag runoff during secondary tapping. Background Technology

[0002] Converters typically employ techniques such as slag-blocking cones, sliding plate slag-blocking devices, and slag detection to prevent slag from falling during the tapping process. However, if the furnace is prematurely lifted due to misjudgment or excessively high slag level during tapping, resulting in incomplete tapping of molten steel, it not only affects the control of the alloy composition of the furnace but also hinders the effectiveness of slag splashing for furnace protection, significantly increasing the difficulty of furnace maintenance. Therefore, when there is excessive molten steel remaining in the furnace, a secondary tapping process is required. However, in the early stages of secondary tapping, the low molten steel level and slow furnace shaking speed can easily cause slag mixing, leading to a reassessment of high phosphorus levels in the molten steel.

[0003] In current production, during secondary tapping, a sliding plate slag-blocking system is typically used. The sliding plate is opened after the converter reaches the tapping angle, effectively preventing slag from falling into the early stages of secondary tapping. However, many converters (especially small converters) are still not equipped with sliding plate slag-blocking systems and cannot use this technology.

[0004] In current production, a slag-blocking cap is placed on the tapping spout before the second tapping. However, due to the mismatch between the slag-blocking cap and the tapping spout, and the fact that the temporary slag-blocking cap has not been sintered at high temperature, the high-temperature liquid slag in the early stage of the second tapping will directly wash away the slag-blocking cap, causing slag to fall. This technology is not very effective in preventing slag from falling in the early stage of the second tapping. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a method for preventing slag from entering the ladle during secondary tapping, by reducing the slag temperature and turning the liquid slag into a semi-molten state, thereby effectively preventing slag from being drawn into the tapping opening and entering the ladle during secondary tapping.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for preventing slag runoff during secondary tapping, comprising the following steps:

[0007] S1. After the first tapping, confirm the ladle is empty, the tapping amount, and the amount of molten steel remaining in the furnace.

[0008] S2, after the molten steel arrives at the argon station, the temperature is measured to confirm that the temperature of the molten steel meets the conditions for secondary tapping.

[0009] S3, after the converter is rocked to zero, start the nitrogen blowing process with a nitrogen flow rate of 22000 m³ / h. 3 / h, keep the lance position at the initial lance position of 2500mm, blow nitrogen for about 40 to 60 seconds, and lift the lance after slag begins to rise in the furnace;

[0010] S4, after the converter is moved to the rear of the furnace and the slag-blocking cap is put on, the second tapping of steel begins;

[0011] S5: After the molten steel has been poured out, lift the furnace. The timing of lifting the furnace is the same as in normal operation.

[0012] Optionally, 800 kg of lime slurry can be added during the nitrogen blowing process.

[0013] Optionally, before the second tapping, the ladle car is driven into position, and the converter is directly pressed to 90°.

[0014] Optionally, after the molten steel has been poured out, 200-300 kg of lime slag can be added to the ladle.

[0015] The beneficial effects of this invention are as follows: This invention provides a method for preventing slag runoff during secondary tapping, which reduces the high phosphorus content in the slag caused by secondary tapping, thus reducing the impact of slag runoff on alloy yield; and when molten steel is not completely tapped due to operational errors or other reasons, this invention can eliminate the negative impact of secondary tapping, salvage the composition deviation caused by incomplete tapping of molten steel, and eliminate the impact of incomplete tapping on slag splashing and furnace protection.

[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 preventing slag runoff during secondary tapping, comprising the following steps:

[0019] 1. After the first tapping, confirm the ladle is empty, the tapped amount, and the amount of molten steel remaining in the furnace;

[0020] 2. After the molten steel reaches the argon station, the temperature is measured to confirm that the temperature of the molten steel meets the conditions for secondary tapping;

[0021] 3. After the converter is shaken to zero, begin nitrogen blowing with the lower lance at a flow rate of 22,000 m³ / h. 3 / h, the gun position remains at the initial gun position of 2500mm;

[0022] 4. Add 800 kg of lime slurry during the nitrogen blowing process;

[0023] 5. After blowing nitrogen for about 40-60 seconds, lift the lance once slag begins to rise inside the furnace;

[0024] 6. After the converter is tilted to the rear, the slag-blocking cap is put on, and then the second tapping begins;

[0025] 7. Before the second tapping, the ladle car is driven into position, and the converter is directly pressed to 90°.

[0026] 8. After the molten steel has been poured out, lift the furnace. The timing of lifting the furnace is the same as in normal operation.

[0027] 9. After the molten steel has been poured out, add 200-300 kg of lime slag to the ladle.

[0028] Specific Implementation Example 1,

[0029] In the HRB400E blowing process, the molten steel was not completely tapped during the first tapping. The ladle sample contained 0.61% Si (target 0.40-0.60%), 1.61% Mn (target 1.30-1.55%), and 0.031% P. Using this method for the second tapping, after the molten steel was completely tapped, the ladle sample was taken again and found to contain 0.51% Si, 1.38% Mn, and 0.032% P. The amount of phosphorus recovered during the second tapping was only 0.001%. The amount of slag added during the entire second tapping process was controlled, and because the Si and Mn composition (mass fraction) was within the internal control range after the molten steel was completely tapped.

[0030] Specific embodiment 2,

[0031] In the HRB400E blowing process, the molten steel was not completely discharged during the first tapping. The ladle sample showed Mn 1.50% and P 0.025%. This method was adopted for the second tapping. After the molten steel was discharged, the ladle sample was taken again and found to have Mn 1.34% and P 0.026%. The amount of phosphorus returned during the second tapping was only 0.001%. The amount of slag discharged was controlled throughout the entire second tapping process.

[0032] 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 preventing slag runoff during secondary tapping, characterized in that, Includes the following steps: S1. After the first tapping, confirm the ladle is empty, the tapping amount, and the amount of molten steel remaining in the furnace. S2, after the molten steel arrives at the argon station, the temperature is measured to confirm that the temperature of the molten steel meets the conditions for secondary tapping. S3, after the converter is rocked to zero, start the nitrogen blowing process with a nitrogen flow rate of 22000 m³ / h. 3 / h, keep the lance position at the initial lance position of 2500mm, blow nitrogen for 40~60s, and lift the lance after slag begins to rise in the furnace; add 800kg of lime slag during the nitrogen blowing process of lowering the lance; S4, after the converter is moved to the rear of the furnace and the slag-blocking cap is put on, the second tapping of steel begins; S5, after the molten steel has been poured out, lift the furnace at the same time as the normal operation; after the molten steel has been poured out, add 200-300 kg of lime slag to the ladle.

2. The method for preventing slag runoff during secondary tapping according to claim 1, characterized in that: Before the second tapping, the ladle car is driven into position, and the converter is directly pressed to 90°.