Method for improving slag stopping effect in converter tapping process

Abstract

The invention discloses a method for improving the slag stopping effect in the converter tapping process, and belongs to the technical field of converter steelmaking. The compressed gas spray head is additionally arranged at the position of the furnace cap, compressed gas is sprayed to the direction of the tapping hole in the later stage of tapping, smoke near the tapping hole is blown, the detection effect of the tapping detection system on the tapping process is improved, a large amount of slag in a steel ladle is avoided, and the situation that tapping is not clean due to the fact that a sliding plate is closed in advance is completely eradicated. After the technical scheme is adopted, the slag stopping effect of the converter is improved, the slag stopping success rate reaches 100%, and the rephosphorization amount of the obtained molten steel is reduced by 25 ppm compared with that before transformation, so that the consumption of a deoxidizing agent is reduced by 0.2 kg / t, the slag carrying amount of the molten steel is obviously reduced, and the quality of the molten steel is obviously improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of converter steelmaking, in particular to a method for improving the effect of slag blocking during the tapping process of a converter. BACKGROUND

[0002] At the end of the tapping process of a converter, the slag often flows out with the molten steel. Too much slag not only reduces the quality of the molten steel, but also may cause the composition of the molten steel to be out of tolerance, resulting in waste. Therefore, slag separation is required at the later stage of the tapping process. Currently, a sliding plate is generally used for slag blocking in large converters, that is, the sliding plate is closed when slag is found at the tapping hole. Therefore, timely and accurate detection of the slag flow condition of the converter is of great significance for ensuring the quality of the molten steel and prolonging the service life of the equipment.

[0003] The infrared monitoring system for slag flow in a converter is a high-tech system used for real-time monitoring and control of the slag flow condition during the steelmaking process in a converter. The infrared monitoring system for slag flow in a converter mainly uses infrared thermal imaging technology to monitor the flow of molten steel and slag in real time. The infrared thermal imaging technology can monitor the flow of molten steel and slag during the tapping process of a converter in real time, and realize high-precision slag identification through thermal radiation differences. Since the thermal radiation capabilities of molten steel and slag are different in the infrared frequency range, the infrared thermometer can remotely and continuously capture and monitor the tapping image in real time, and transmit it back to the system for image segmentation and identification calculation.

[0004] The application effect of the infrared monitoring system for slag flow in a converter is remarkable. The infrared thermal imaging monitoring system can be applied to the steelmaking process of converters of different scales and types, and has strong adaptability and flexibility. However, during the tapping process of a converter, smoke and dust are inevitably generated due to the addition of alloys, deoxidizers and part of the slag modifier, which interferes with the slag flow infrared monitoring system and causes false alarms. When the false alarms are serious, the slag flow infrared monitoring system will make a false detection, causing a large amount of slag in the ladle and resulting in the scrapping of the whole furnace. Therefore, reducing the interference of smoke and dust in the ladle on the slag flow system is the key to improving the effect of slag blocking and improving the quality of the molten steel. SUMMARY

[0005] In view of the above prior art, the purpose of the present application is to provide a method for improving the effect of slag blocking during the tapping process of a converter.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solutions: In a first aspect of the present application, a converter with a compressed gas nozzle is provided. The converter cap is provided with a compressed gas nozzle. The nozzle of the compressed gas nozzle is of the Laval type, and the nozzle is divided into three rows. The direction of the nozzles in the middle row is perpendicular to the flow direction of the molten steel during tapping.

[0007] Further, the angles between the remaining two rows and the middle row are 30° and -30°, respectively.

[0008] Further, the distance between each row of nozzles is 5-10 cm, the number of nozzles in each row is 2-4, and the distance between each nozzle is 5-10 cm.

[0009] Further, the distance between each row of nozzles is 7.5 cm, the number of nozzles in each row is 3, and the distance between each nozzle is 7.5 cm.

[0010] Further, the throat diameter of the nozzle is 5-15 mm, and the expansion angle is 10-12°.

[0011] Further, the nozzle can be independently opened and closed.

[0012] In the second aspect of the present application, a method for improving the slag blocking effect during the tapping process of a converter is provided, wherein the converter with the compressed gas nozzle is used during the smelting of the converter, compressed gas is sprayed towards the tapping hole in the late stage of the tapping, and automatic slag detection is performed by using an infrared slag monitoring system, and the tapping hole slide plate is closed after the tapping is completed.

[0013] Further, the spraying pressure is 0.05-0.3 Mpa.

[0014] Further, the spraying gas is one of compressed air, nitrogen, carbon dioxide or argon.

[0015] Further, when the produced steel grade is a high-grade clean steel, the spraying gas is argon.

[0016] The beneficial effects of the present application are as follows: The present application adds a compressed gas nozzle at the position of the furnace cap, sweeps the smoke near the tapping hole, improves the detection effect during the tapping process, avoids a large amount of slag in the ladle, and eliminates the situation of incomplete tapping caused by the early closing of the slide plate. After adopting the technical scheme, the slag blocking effect of the converter is improved, the success rate of slag blocking reaches 100%, the phosphorus content of the obtained molten steel is reduced by 25 ppm compared with before the transformation, the consumption of deoxidizer is reduced by 0.2 kg / t, the amount of slag carried by the molten steel is significantly reduced, and the quality of the molten steel is significantly improved. DETAILED DESCRIPTION

[0017] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs.

[0018] In order for those skilled in the art to more clearly understand the technical solutions of the present application, the technical solutions of the present application will be described in detail below with specific examples.

[0019] The test materials used in the embodiments of the present application, which are not specifically described, are conventional test materials in the art and can be purchased through commercial channels.

[0020] Example 1 The present application adds a compressed gas nozzle at the position of the furnace cap, the nozzle of the compressed gas nozzle is a Laval type, the throat diameter is 10 mm, and the expansion angle is 11°. The nozzle is divided into three rows, each row is spaced 7.5 cm apart; each row has three, each spaced 7.5 cm apart. The middle row of nozzles is directed towards perpendicular to the direction of the molten steel flow during tapping, and the other two rows are at angles of 30° and -30°, respectively, to the middle row. During the later stage of tapping, compressed gas is blown towards the taphole, and the blowing pressure is 0.05-0.3 MPa. For ordinary steel grades, the blowing gas is compressed air, and for high-grade clean steel, the blowing gas is argon.

[0021] The switch of the compressed gas can be linked to the furnace tilting angle, and is automatically opened during the later stage of tapping. Any one or more rows of nozzles can be selected to be opened according to the situation, and is automatically closed after tapping is completed, so as to realize automatic control. Automatic slag detection is performed by using a slag detection system. The taphole slide is closed after tapping is completed, and the compressed gas is closed.

[0022] According to the above control method, the control situation is as follows when it is implemented in a 120 t converter in a domestic steel plant: 1. A compressed gas nozzle is added at the position of the furnace cap, and the nozzle direction is towards the taphole.

[0023] 2. When the tapping is 1 / 4, the converter tilting angle is -93°, and the deoxidizer alloy is started to be added.

[0024] 3. When the tapping is 3 / 4, the converter tilting angle is -98°, the alloy addition is completed, the compressed gas valve is automatically opened, the compressed air is blown towards the taphole, and the blowing pressure is 0.2 MPa.

[0025] 4. After the tapping is completed, the slag detection system detects the taphole slag, and the slide is automatically closed.

[0026] 5. The converter tilting angle is -60°, and the compressed air is automatically closed.

[0027] Comparative Example 1 1. The taphole slide is closed, the converter tilting angle is -90°, the taphole slide is opened, and the tapping starts.

[0028] 2. When the tapping is 1 / 4, the converter tilting angle is -93°, and the deoxidizer alloy is started to be added.

[0029] 3. When the tapping is 3 / 4, the converter tilting angle is -98°, and the deoxidizer alloy addition is completed.

[0030] 4. During the later stage of tapping, because the alloy in the ladle is not completely melted, the smoke is large, the converter slag infrared monitoring system does not alarm, the slide is not timely closed, and the amount of slag in the ladle is large.

[0031] 5, The molten steel returns phosphorus due to slagging, and the phosphorus exceeds the quality requirement, resulting in the whole furnace being waste.

[0032] Comparative Example 2 1, Close the tundish slide, rotate the converter at an angle of -90°, open the tundish slide, and start tapping.

[0033] 2, When tapping 1 / 4, rotate the converter at an angle of -93°, and start adding deoxidizer alloy.

[0034] 3, When tapping 3 / 4, rotate the converter at an angle of -98°, and complete the addition of deoxidizer alloy.

[0035] 4, In the late stage of tapping, due to incomplete melting of the alloy in the ladle, there is a lot of smoke, the converter slagging infrared monitoring system gives a false alarm, the slide is closed prematurely, and the tapping is not complete.

[0036] 5, Due to the small tapping amount, the alloy composition is high, and the cost is high.

[0037] Test Example In a domestic steel plant, a converter with a compressed gas nozzle added at the furnace cap position according to the method of Example 1 was used, and a converter without the compressed gas nozzle (before modification) was used, the converter volume was 120 t, and each test was 100 furnaces, and the effects of slag blocking were compared as shown in Table 1: Table 1 Comparison of using the method of Example 1 and the method before modification As can be seen from the results in Table 1, by using the method of the present application for metallurgical control, stable control of the converter tapping process is achieved, the amount of phosphorus returned by using the method of adding a nozzle is reduced by 25 ppm compared with before modification, the consumption of deoxidizer is reduced by 0.2 kg / t, efficient steel slag separation is achieved, the quality control level of the converter is improved, and the cost is reduced.

[0038] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A converter with a compressed gas nozzle, characterized in that, The converter's furnace cap is equipped with compressed gas nozzles; the nozzles of the compressed gas nozzles are Laval type, with the nozzles divided into three rows, and the middle row of nozzles facing the direction of the molten steel flow perpendicular to the tapping direction.

2. The converter with compressed gas nozzle according to claim 1, characterized in that, The angles between the other two rows and the middle row are 30° and -30°, respectively.

3. The converter with compressed gas nozzle according to claim 1, characterized in that, The nozzles are spaced 5-10cm apart in each row, with 2-4 nozzles per row and 5-10cm apart in each nozzle.

4. The converter with compressed gas nozzle according to claim 3, characterized in that, The nozzles are spaced 7.5cm apart in each row, with 3 nozzles per row and 7.5cm apart in each nozzle.

5. The converter with a compressed gas nozzle according to claim 1, characterized in that, The nozzle throat diameter is 5-15mm, and the expansion angle is 10-12°.

6. The converter with a compressed gas nozzle according to claim 1, characterized in that, The nozzle can be opened and closed independently.

7. A method for improving the slag-blocking effect during converter tapping, characterized in that, During converter smelting, a converter with compressed gas nozzles as described in any one of claims 1-6 is used. In the later stage of tapping, compressed gas is injected towards the tapping port, and an infrared monitoring system for slag discharge is used for automatic slag discharge detection. The tapping port slide is closed after tapping is completed.

8. The method for improving the slag-blocking effect during converter tapping according to claim 7, characterized in that, The blowing pressure is 0.05~0.3Mpa.

9. The method for improving the slag-blocking effect during converter tapping according to claim 7, characterized in that, The blowing gas is one of compressed air, nitrogen, carbon dioxide or argon.

10. The method for improving the slag-blocking effect during converter tapping according to claim 9, characterized in that, When producing high-grade clean steel, the blowing gas is argon.

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