Method for preventing the clogging of a ladle nozzle during the casting of a straight-up non-calcium treated steel grade

Abstract

The present application relates to a method for preventing the clogging of a ladle nozzle during pouring of a straight-up non-calcium treated steel grade, and belongs to the technical field of steel smelting. The method controls the amount of slag during tapping, increases the stirring intensity of the ladle bottom argon blowing during tapping, does not add calcium-containing ferroalloy during tapping, uses large-flow argon blowing stirring during the process from tapping to the argon blowing station, uses large-flow stirring of the molten steel at the argon blowing station, ensures the soft argon blowing time, increases the molten steel setting process, and effectively prevents the clogging of the ladle nozzle.

Description

Technical Field

[0001] This invention belongs to the field of iron and steel smelting technology and relates to a method for preventing blockage of the ladle nozzle during the casting process of non-calcium treated steel grades directly from the converter. Background Technology

[0002] During continuous casting, it's common to experience a decreasing flow of steel in the ladle and a continuous drop in the tundish liquid level, a phenomenon known as "the ladle steel flow failing to pick up." This is because inclusions in the molten steel continuously accumulate at the top and bottom nozzles of the ladle, clogging them. For most steel grades, the primary method to alleviate this clogging is through a calcium treatment process, where calcium wire is fed into the ladle during the refining stage. However, for non-calcium-treated steel grades produced by direct converter casting, calcium treatment alters the composition of inclusions, failing to meet user requirements. Some steel mills also employ processes such as converter slag washing and ladle argon blowing to mitigate ladle nozzle clogging. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a method for preventing clogging of the ladle nozzle during the casting process of non-calcium treated steel grades directly fed into the converter, so as to solve the problem of ladle nozzle clogging.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] To prevent clogging of the ladle nozzle during the casting process of non-calcium treated steel grades directly from the converter, the necessary manganese alloy and aluminum alloy for the steel grade are added during the converter tapping process. The aluminum alloy is added at 0.3 times the target Al content of the steel grade. Subsequently, small-particle lime is added at a rate of 2.5-3.5 kg / t. Argon gas is blown into the ladle for stirring throughout the tapping process to ensure good alloy melting and lime melting.

[0006] During the process of transferring the ladle from the converter to the argon blowing station, the ladle is kept under constant argon blowing and stirring, with an argon blowing flow rate of 20–30 Nm³. 3 / h;

[0007] After the ladle is moved to the argon blowing station, temperature is measured, samples are taken, and oxygen is determined. Aluminum wire is added according to the steel composition; ordinary ferrosilicon with a calcium content of 1-1.5% must not be added. During this stage, in addition to oxygen determination, argon blowing into the ladle is performed at 30-60 Nm. 3 / h for ≥3min, the remaining time at 20~30Nm 3 / h argon blowing and stirring; if slag appears, oxygen determination is required for confirmation, and aluminum wire should be added at 30-60 Nm. 3 The flow rate should be maintained at ≥2 min / h; when the temperature and composition of the molten steel reach the refining target of the steel grade, the color of the slag sample should be grayish-white or white, and the bottom blowing argon flow rate should be adjusted to 5-10 Nm. 3 / h, 5min≤duration≤10min, ladle leaves the station and is moved to the continuous casting rotary body;

[0008] After the ladle is moved to the continuous casting rotating body, the ladle is left to stand on the continuous casting rotating body for 3 to 5 minutes before pouring. During the pouring process, the ladle nozzle is kept fully open and the ladle protection pipe is well sealed.

[0009] At the end of the molten steel casting process, the slag discharge from the ladle is monitored so that the ladle slide can be closed in a timely manner to prevent a large amount of ladle slag from entering the tundish.

[0010] Optionally, the alloys added during the converter tapping process are all low-calcium alloys, with ferrosilicon alloys having a Ca content of ≤1.0%.

[0011] Optionally, before tapping from the converter, the bottom blowing argon flow rate of the ladle is 5–10 Nm³. 3 When the steel output reaches 60-80 tons per hour, after adding alloy slag, the bottom-blowing argon flow rate of the ladle is 30-60 Nm³. 3 / h, until all the molten steel in the converter is discharged, to ensure the removal effect of deoxidation products in one step.

[0012] Optionally, if the bottom argon blowing effect of the ladle is poor, open the ladle argon blowing through valve to ensure good argon blowing effect.

[0013] Optionally, if slag appears on the ladle during the tapping process after the converter molten steel has been tapped, 1.5 to 2.5 kg / t of lime should be added to reduce the oxidizing properties of the ladle slag.

[0014] Optionally, the ladle pouring process can be initiated by pulling the slide plate to its maximum position in one go.

[0015] Optionally, at the end of the molten steel casting process, the slag discharge from the ladle can be used to detect the slag discharge situation.

[0016] Optionally, after pouring, if the ladle remains on the rotary table for ≤15 minutes, the ladle is lifted and the slag is turned over.

[0017] Optionally, the converter tapping process adopts a sliding plate slag-blocking process.

[0018] The beneficial effects of this invention are: it effectively prevents the sprue nozzle from becoming clogged, and the practical results are ideal.

[0019] 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

[0020] 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.

[0021] To prevent clogging of the ladle nozzle during the casting process of non-calcium treated steel grades directly from the converter, the necessary manganese alloy and aluminum alloy for the steel grade are added during the converter tapping process. The aluminum alloy is added at 0.3 times the target Al content of the steel grade. Subsequently, small-particle lime is added at a rate of 2.5-3.5 kg / t. Argon gas is blown into the ladle for stirring throughout the tapping process to ensure good alloy melting and lime melting.

[0022] During the process of transferring the ladle from the converter to the argon blowing station, the ladle is kept under constant argon blowing and stirring, with an argon blowing flow rate of 20–30 Nm³. 3 / h;

[0023] After the ladle is moved to the argon blowing station, temperature is measured, samples are taken, and oxygen is determined. Aluminum wire is added according to the steel composition; ordinary ferrosilicon with a calcium content of 1-1.5% must not be added. During this stage, in addition to oxygen determination, argon blowing into the ladle is performed at 30-60 Nm. 3 / h for ≥3min, the remaining time at 20~30Nm 3 / h argon blowing and stirring; if slag appears, oxygen determination is required for confirmation, and aluminum wire should be added at 30-60 Nm. 3 The flow rate should be maintained at ≥2 min / h; when the temperature and composition of the molten steel reach the refining target of the steel grade, the color of the slag sample should be grayish-white or white, and the bottom blowing argon flow rate should be adjusted to 5-10 Nm. 3 / h, 5min≤duration≤10min, ladle leaves the station and is moved to the continuous casting rotary body;

[0024] After the ladle is moved to the continuous casting rotating body, the ladle is left to stand on the continuous casting rotating body for 3 to 5 minutes before pouring. During the pouring process, the ladle nozzle is kept fully open and the ladle protection pipe is well sealed.

[0025] At the end of the molten steel casting process, the slag discharge from the ladle is monitored so that the ladle slide can be closed in a timely manner to prevent a large amount of ladle slag from entering the tundish.

[0026] Optionally, the alloys added during the converter tapping process are all low-calcium alloys, with ferrosilicon alloys having a Ca content of ≤1.0%.

[0027] Optionally, before tapping from the converter, the bottom blowing argon flow rate of the ladle is 5–10 Nm³. 3 When the steel output reaches 60-80 tons per hour, after adding alloy slag, the bottom-blowing argon flow rate of the ladle is 30-60 Nm³. 3 / h, until all the molten steel in the converter is discharged, to ensure the removal effect of deoxidation products in one step.

[0028] Optionally, if the bottom argon blowing effect of the ladle is poor, open the ladle argon blowing through valve to ensure good argon blowing effect.

[0029] Optionally, if slag appears on the ladle during the tapping process after the converter molten steel has been tapped, 1.5 to 2.5 kg / t of lime should be added to reduce the oxidizing properties of the ladle slag.

[0030] Optionally, the ladle pouring process can be initiated by pulling the slide plate to its maximum position in one go.

[0031] Optionally, at the end of the molten steel casting process, the slag discharge from the ladle can be used to detect the slag discharge situation.

[0032] Optionally, after pouring, if the ladle remains on the rotary table for ≤15 minutes, the ladle is lifted and the slag is turned over.

[0033] Optionally, the converter tapping process adopts a sliding plate slag-blocking process.

[0034] This invention effectively prevents ladle nozzle blockage by controlling the amount of slag discharged during converter tapping, increasing the intensity of bottom argon blowing during tapping, avoiding the addition of calcium-containing ferroalloys during tapping, employing high-flow-rate argon blowing and stirring from tapping to the argon blowing station, ensuring sufficient soft argon blowing time at the argon blowing station, and increasing the molten steel calming process. This invention can prevent ladle nozzle blockage and nodule formation when directly casting non-calcium treated steel grades from the converter, ensuring continuous casting.

[0035] Example

[0036] A method for preventing ladle nozzle blockage during the direct casting process of non-calcium treated steel grades in a converter, applicable to the production of non-calcium treated steel grades using a 210-ton BOF-argon blowing station-CC:

[0037] 1. The converter tapping process adopts the sliding plate slag-blocking process. During the tapping process, the necessary manganese alloy and aluminum alloy for the steel grade are added, especially the aluminum alloy is added at 0.3 times the target Al content of the steel grade; then small-particle lime is added at a rate of 2.5-3.5 kg / t. Argon gas is blown into the ladle for stirring throughout the tapping process to ensure good alloy melting and lime melting.

[0038] 2. All alloys added during the steelmaking process are low-calcium alloys, especially ferrosilicon alloys with Ca≤1.0%.

[0039] 3. Before tapping, the argon flow rate at the bottom of the ladle is 5-10 Nm³. 3 / h. When the steel output reaches 60-80 tons, after adding alloy slag, the bottom blowing argon flow rate of the ladle is 30-60 Nm. 3 / h, until all the molten steel in the converter is discharged, ensuring the removal effect of deoxidation products in one pass. If the bottom argon blowing effect of the ladle is found to be poor (bright ring ≤300mm), open the ladle argon blowing straight valve (the same below) to ensure good argon blowing effect.

[0040] 4. If slag is found in the ladle after the molten steel has been tapped from the converter, 1.5 to 2.5 kg / t of lime should be added to reduce the oxidizing properties of the ladle slag.

[0041] 5. During the process of the ladle car moving from the bottom of the converter to the argon blowing station, the ladle is constantly under argon blowing and stirring, with an argon blowing flow rate of 20-30 Nm³. 3 / h.

[0042] 6. After the ladle arrives at the argon blowing station, temperature is measured, samples are taken, and oxygen is determined. Aluminum wire is added according to the steel composition, but ordinary ferrosilicon (containing approximately 1-1.5% calcium) must not be added. During this stage, in addition to oxygen determination, argon blowing into the ladle is performed at 30-60 Nm. 3 / h for ≥3min, the remaining time at 20~30Nm 3 Argon blowing and stirring at / h. If slag formation occurs, oxygen determination is required for confirmation, and aluminum wire should be added at 30-60 Nm. 3 / h lasts for ≥2min.

[0043] 7. When the temperature and composition of the molten steel reach the refining target for the steel grade, observe the slag sample; the color should be grayish-white or white. Adjust the bottom-blown argon flow rate to 5–10 Nm³. 3 / h, 5min≤duration≤10min, molten steel exits the station.

[0044] 8. The ladle arrives at the continuous casting rotating body and is left to stand on the rotating body for 3-5 minutes before casting begins. During the casting process, the slide plate is pulled to its maximum position in one go before casting begins.

[0045] 9. During the pouring process, the sliding plate switch must not be pulled arbitrarily to ensure that the ladle nozzle is fully open. The ladle protection pipe must be properly sealed.

[0046] 10. At the end of the molten steel casting process, the slag discharge situation in the ladle is monitored using the ladle slag discharge detection method. The ladle slide plate is closed in a timely manner to prevent a large amount of ladle slag from entering the tundish.

[0047] 11. After pouring is completed, the ladle should remain on the rotary table for ≤15 minutes before hoisting the ladle to remove slag.

[0048] Verification has shown that the method of this invention can prevent clogging of the ladle nozzles, and the practical results are ideal.

[0049] 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 clogging of the ladle nozzle during the casting process of non-calcium treated steel grades directly from the converter, characterized in that: During the converter tapping process, necessary manganese alloys and aluminum alloys for the steel grade are added, with the aluminum alloys added at 0.3 times the target Al content of the steel grade. Subsequently, small-particle lime is added at a rate of 2.5~3.5 kg / t. Argon gas is blown into the ladle for stirring throughout the tapping process to ensure good alloy melting and lime melting. During the process of moving the ladle from the converter to the argon blowing station, the ladle is kept under constant argon blowing and stirring, with an argon blowing flow rate of 20~30 Nm³. 3 / h; After the ladle is moved to the argon blowing station, temperature is measured, samples are taken, and oxygen is determined. Aluminum wire is added according to the steel composition; ordinary ferrosilicon with a calcium content of 1-1.5% must not be added. During this stage, in addition to oxygen determination, argon blowing into the ladle is performed at 30-60 Nm. 3 / h for ≥3min, the remaining time at 20~30Nm 3 / h argon blowing and stirring; if slag appears, oxygen determination is required for confirmation, and aluminum wire should be added at 30~60Nm. 3 The flow rate should be maintained at ≥2 min / h; when the temperature and composition of the molten steel reach the refining target of the steel grade, the color of the slag sample should be grayish-white or white, and the bottom blowing argon flow rate should be adjusted to 5~10 Nm. 3 / h, 5min≤duration≤10min, ladle leaves the station and is moved to the continuous casting rotary body; After the ladle is moved to the continuous casting rotating body, the ladle is left to stand on the continuous casting rotating body for 3 to 5 minutes before pouring. During the pouring process, the ladle nozzle is kept fully open and the ladle protection pipe is well sealed. At the end of the molten steel casting process, the slag discharge from the ladle is monitored so that the ladle slide can be closed in time to prevent a large amount of ladle slag from entering the tundish. All alloys added during the converter tapping process are low-calcium alloys, with ferrosilicon alloys having a Ca content of ≤1.0%. Before tapping from the converter, the bottom blowing argon flow rate of the ladle is 5~10 Nm³. 3 When the steel output reaches 60-80 tons per hour, after adding alloy slag, the bottom-blowing argon flow rate of the ladle is 30-60 Nm³. 3 / h, until all the molten steel in the converter is discharged, to ensure the removal effect of deoxidation products in one step.

2. The method for preventing ladle nozzle blockage during the casting process of non-calcium treated steel grades directly fed into the converter, as described in claim 1, is characterized in that: If the bottom argon blowing effect of the ladle is poor, open the ladle argon blowing direct valve to ensure good argon blowing effect.

3. The method for preventing ladle nozzle blockage during the casting process of non-calcium treated steel grades directly fed into the converter, as described in claim 1, is characterized in that: If slag appears on the ladle during the tapping process after the molten steel has been tapped from the converter, 1.5~2.5 kg / t of lime should be added to reduce the oxidizing properties of the ladle slag.

4. The method for preventing ladle nozzle blockage during the casting process of non-calcium treated steel grades directly fed into the converter according to claim 1, characterized in that: The ladle pouring process begins with pulling the slide plate to its maximum position in one go.

5. The method for preventing ladle nozzle blockage during the casting process of non-calcium treated steel grades directly fed into the converter according to claim 1, characterized in that: At the end of the molten steel casting process, the slag discharge from the ladle is used to detect the slag discharge situation.

6. The method for preventing ladle nozzle blockage during the casting process of non-calcium treated steel grades directly fed into the converter according to claim 1, characterized in that: After pouring is completed, the ladle should remain on the rotary table for ≤15 minutes before being hoisted and the slag removed.

7. The method for preventing ladle nozzle blockage during the casting process of non-calcium treated steel grades directly fed into the converter according to claim 1, characterized in that: The converter tapping process uses a sliding plate slag-blocking technology.