Method for preventing secondary oxidation of tundish molten steel

Abstract

The invention discloses a method for preventing secondary oxidation of tundish molten steel, and belongs to the technical field of steel smelting. According to the method, a plurality of pipelines used for blowing inert gas are evenly inserted into the tundish cover plate, a flow adjusting valve is arranged on the argon pipeline, inert gas with a certain flow is continuously blown in through the pipelines used for blowing inert gas, inert gas protection is formed in the whole casting time, and the argon flow is adjusted. And the oxygen content in tundish air is reduced, and the purpose of reducing secondary oxidation is achieved. The invention aims to provide a method for preventing secondary oxidation of tundish molten steel. The total oxygen content, nitrogen increase and the like in the molten steel are effectively reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of steel smelting, and in particular relates to a method for preventing secondary oxidation of molten steel in a tundish. Background Art

[0002] The contact area between the molten steel and the air or slag layer in the tundish is large, and the clearance of the tundish is also large, so secondary oxidation is very likely to occur, resulting in oxidation of the molten steel, excessive inclusions and other problems. At present, the common practice is generally to introduce argon after baking the tundish to form argon protection for the initial molten steel after the tundish is poured. Among them, the patent "A device for preventing secondary oxidation of molten steel in the tundish" (CN 205673577 U) is a typical improvement example. However, in the subsequent casting process, the residual argon is gradually diluted, and the external air gradually enters, causing subsequent secondary oxidation of the molten steel. In the past, argon protection was not performed during casting. Now it is generally used to perform argon protection before casting (no subsequent protection), and the subsequent secondary oxidation cannot be ignored. The present invention is mainly aimed at this problem, and argon is continuously introduced in the future to protect the top of the molten steel. The main principle is to reduce the oxygen content by evacuating the oxygen in the tundish, thereby reducing secondary oxidation. The chemical reaction is faster and the effect will be better. Summary of the invention

[0003] The purpose of the present invention is to provide a method for preventing secondary oxidation of molten steel in a tundish. A new method is proposed for the problem of secondary oxidation of molten steel in a tundish during industrial production. The method mainly includes the following steps: under the conditions of conventional sealing of the tundish cover and blowing in inert gas protection (the conventional method currently performs argon gas protection before pouring, and does not perform subsequent argon gas blowing), inert gas harmless to molten steel is continuously blown into the subsequent pipeline, and oxygen in the clearance of the tundish is emptied to reduce the oxygen partial pressure, thereby further reducing secondary oxidation. Specifically, the flow rate of the blown inert gas can be adjusted according to actual conditions. When pouring or the liquid level is low, the flow rate is increased to empty a large amount of oxygen in the clearance of the tundish. Precautions mainly include that the insertion of the pipeline should be selected in places where secondary oxidation is serious, such as places with poor sealing performance and places where water nozzles are inserted. The insertion depth should ensure that the cleanliness of the molten steel is not affected, so as to prevent the blown gas from impacting the molten steel and slag layer in the tundish, exposing the molten steel to secondary oxidation and slag rolling, resulting in excessive inclusions. The present invention is simple and easy to operate, and will not cause any impact on the production rhythm.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] The present invention discloses a method for preventing secondary oxidation of molten steel in a tundish. The method comprises the following steps: uniformly inserting a plurality of pipes for blowing inert gas at a tundish cover plate, arranging a flow regulating valve on the argon gas pipe, and continuously and uninterruptedly blowing inert gas of a certain flow rate through the plurality of pipes for blowing inert gas, thereby forming inert gas protection during the entire pouring process, reducing the oxygen content in the air of the tundish, and achieving the purpose of reducing secondary oxidation.

[0006] Furthermore, the blowing flow rate of the inert gas is controlled to be ≤1m 3 / h.

[0007] Furthermore, the inert gas is argon or helium.

[0008] Furthermore, the flow rate of the blown inert gas can be adjusted according to actual conditions.

[0009] Furthermore, when pouring or the liquid level is low, the flow rate of each branch can be increased to 0.8-1m 3 / h, exhausting a large amount of oxygen in the clearance space of the tundish.

[0010] Furthermore, the inserted argon gas pipeline is inserted into a place where secondary oxidation is serious.

[0011] Furthermore, the places where the secondary oxidation is serious include places with poor sealing and places where the water inlet is inserted.

[0012] Furthermore, the insertion depth should ensure that it does not affect the cleanliness of the molten steel, so as to prevent the blown gas from impacting the molten steel and slag layer in the tundish, exposing the molten steel to secondary oxidation and slag rolling, resulting in excessive inclusions.

[0013] Compared with the prior art, the beneficial technical effects of the present invention are:

[0014] The present invention is a new method for the problem of secondary oxidation of molten steel in the tundish during industrial production. Mainly, under the conditions of conventional sealing of the tundish cover and blowing inert gas protection (the conventional method currently performs argon gas protection before pouring, and does not perform subsequent argon gas blowing), an inert gas harmless to the molten steel is continuously blown into the subsequent pipeline, and the oxygen in the clearance of the tundish is emptied to reduce the oxygen partial pressure, thereby further reducing the secondary oxidation. Specifically, the flow rate of the blown inert gas can be adjusted according to the actual situation. When pouring or the liquid level is low, the flow rate is increased to empty a large amount of oxygen in the clearance of the tundish. Precautions mainly include that the insertion of the pipeline should be selected in places where secondary oxidation is serious, such as places with poor sealing and places where water nozzles are inserted. The insertion depth should ensure that it does not affect the cleanliness of the molten steel, so as to prevent the blown gas from impacting the molten steel and slag layer in the tundish, exposing the molten steel to secondary oxidation and slag rolling, resulting in excessive inclusions. The present invention is simple and easy to operate, and will not cause any impact on the production rhythm. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention will be further described below in conjunction with the accompanying drawings.

[0016] Figure 1 This is a top view of the tundish;

[0017] Figure 2 Schematic diagram of the cross section of the tundish. DETAILED DESCRIPTION

[0018] A method for preventing secondary oxidation of molten steel in a tundish, wherein a plurality of pipes for blowing inert gas are uniformly inserted into the tundish cover plate, and a flow regulating valve is arranged on the argon gas pipe. A certain flow of inert gas is continuously and continuously blown into the tundish through the plurality of pipes for blowing inert gas, so as to form inert gas protection during the entire pouring, reduce the oxygen content in the air of the tundish, and achieve the purpose of reducing secondary oxidation.

[0019] The blowing flow rate of the inert gas is controlled at ≤1m 3 / h. The inert gas is argon or helium, preferably argon. The flow rate of the inert gas can be adjusted according to the actual situation. When pouring or the liquid level is low, increase the flow rate to 0.8-1m 3 / h, and exhaust a large amount of oxygen in the clearance of the tundish. The inserted argon pipeline is inserted in places with severe secondary oxidation, such as places with poor sealing and places where the water inlet is inserted. The insertion depth should ensure that it does not affect the cleanliness of the molten steel to prevent the blown gas from impacting the molten steel and slag layer in the tundish, exposing the molten steel to secondary oxidation and slag rolls, resulting in excessive inclusions.

[0020] Application examples:

[0021] A steel mill uses continuous argon blowing in the tundish to prevent secondary oxidation of the top of the molten steel. It uses sealing measures to seal the tundish and the cover, and protects them by continuously blowing in argon. Based on normal conditions, two pipes are inserted into the poorly sealed parts of the tundish cover to blow in inert gas. See the top view. Figure 1 and cross-sectional diagrams see Figure 2 The height of the inserted pipe is halfway between the steel liquid level and the cover plate. After stable casting, the flow rate of the single blown inert gas is controlled at ≤1m 3 / h. The oxygen content of the steel liquid in the tundish is finally measured to characterize the secondary oxidation effect of the steel liquid. By comparison, it can be found that continuous blowing of inert gas can effectively reduce the total oxygen content and increase nitrogen in the steel liquid.

[0022] The comparison results are shown in the following table:

[0023]

[0024] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preventing secondary oxidation of molten steel in a tundish, characterized in that: By evenly inserting a number of pipes for blowing inert gas at the tundish cover plate and setting a flow regulating valve on the argon gas pipe, a certain flow of inert gas is blown continuously and uninterruptedly through the pipes for blowing inert gas, so as to form inert gas protection during the entire casting process, reduce the oxygen content in the air of the tundish, and achieve the purpose of reducing secondary oxidation.

2. The method for preventing secondary oxidation of molten steel in the tundish according to claim 1, characterized in that: The blowing flow rate of the inert gas is controlled at ≤1m 3 / h.

3. The method for preventing secondary oxidation of molten steel in the tundish according to claim 1, characterized in that: The inert gas is argon or helium.

4. The method for preventing secondary oxidation of molten steel in the tundish according to claim 1, characterized in that: The flow rate of the inert gas blown in can be adjusted according to the actual situation.

5. The method for preventing secondary oxidation of molten steel in tundish according to claim 1, characterized in that: When pouring or the liquid level is low, increase the flow rate of each branch to 0.8-1m 3 / h, exhausting a large amount of oxygen in the clearance space of the tundish.

6. The method for preventing secondary oxidation of molten steel in tundish according to claim 1, characterized in that: The inserted pipe should be inserted into the place where secondary oxidation is serious.

7. The method for preventing secondary oxidation of molten steel in tundish according to claim 1, characterized in that: The places where the secondary oxidation is serious include places with poor sealing and places where the water inlet is inserted.

8. The method for preventing secondary oxidation of molten steel in tundish according to claim 1, characterized in that: The insertion depth should ensure that it does not affect the cleanliness of the molten steel to prevent the blown gas from impacting the molten steel and slag layer in the tundish, exposing the molten steel to secondary oxidation and slag rolling, resulting in excessive inclusions.

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