Alloy liquid blowing denitrification method

Abstract

The invention relates to the technical field of denitrification, in particular to an alloy liquid blowing denitrification method which comprises the following steps: introducing mixed gas consisting of argon and carbon dioxide in proportion into a first blowing pipe and a second blowing pipe which are arranged in a crossed manner in advance; and the ventilated injection pipe is inserted into the middle lower part of the alloy liquid, and during formal work, vacuum denitrification treatment is realized along with contact and stirring of the mixed gas and the alloy liquid. According to the method, argon and carbon dioxide are adopted as mixed gas for blowing denitrification treatment, and meanwhile, the blowing pipes which are arranged in a crossed mode are adopted, so that the nitrogen content of alloy liquid can be greatly reduced; and the ratio of argon to carbon dioxide is optimized, so that the content of oxygen and hydrogen is not obviously increased while the content of nitrogen is reduced, and the quality of the alloy material is improved.

Description

Technical Field

[0001] The invention relates to the technical field of denitrification, in particular to a method for denitrification of alloy liquid by gas blowing. Background Art

[0002] Ladle blowing is a simple off-furnace refining method for degassing molten steel and removing non-metallic inclusions. This method has simple process, cheap equipment and significant refining effect. Depending on the structure of the molten steel at room temperature (such as austenite, ferrite, etc.) and the purpose of treatment, the gas blown into the molten steel can be argon, nitrogen, carbon monoxide, water vapor, air, or first blow in nitrogen, carbon monoxide, water vapor, air, and then argon. Molten steel blowing has important metallurgical significance: (1) reducing the content of dissolved gas (such as hydrogen, nitrogen, oxygen) in the molten steel; (2) removing non-metallic inclusions (such as oxides, sulfides, nitrides, etc.) remaining in the molten steel; (3) making the composition and temperature of the molten steel uniform before pouring, which can significantly reduce the pouring start temperature, realize the normalization of the continuous casting process, and improve the impact toughness of the steel.

[0003] When smelting special alloys with strict requirements on nitrogen content, it is crucial to control the nitrogen content in molten steel. Traditional gasification methods mostly blow pure argon into the surface or middle of the molten steel, resulting in insufficient gas diffusion, low stirring efficiency, and poor denitrification effect, which cannot meet the production requirements of high-standard special alloys. Based on this, a gas blowing denitrification method for alloy liquid is proposed. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a method for denitrification of alloy liquid by gas blowing, which adopts argon and carbon dioxide as a mixed gas for gas denitrification treatment and is assisted by cross-arranged blowing pipes, thereby significantly reducing the nitrogen content of the alloy liquid.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for denitrification of alloy liquid by gas blowing, comprising the following steps:

[0006] (1) Introduce mixed gas into the injection pipe in advance;

[0007] (2) Insert the ventilated blowing pipe into the lower middle part of the alloy liquid, and as the mixed gas contacts and stirs the alloy liquid, vacuum denitrification treatment is achieved.

[0008] Preferably, in step (1), the blow pipe includes a No. 1 blow pipe and a No. 2 blow pipe, and the No. 1 blow pipe and the No. 2 blow pipe are arranged crosswise.

[0009] Preferably, the angle formed between the No. 1 blow pipe and the No. 2 blow pipe is 30-50°.

[0010] Preferably, in step (1), the mixed gas is selected from argon and carbon dioxide, and the volume ratio of argon to carbon dioxide is (8-12):1.

[0011] Preferably, the volume ratio of argon to carbon dioxide is 10:1.

[0012] Preferably, in step (1), the flow rate of the mixed gas is 50-60NL / min.

[0013] Preferably, in step (2), the initial oxygen content of the alloy liquid is 0.02%, the initial hydrogen content is 0.001%, and the initial nitrogen content is 0.012%.

[0014] Preferably, in step (2), the vacuum denitrification treatment time is 12-30 minutes.

[0015] The present invention provides a method for denitrification of alloy liquid by gas blowing, which has the following beneficial effects compared with the prior art:

[0016] The present invention adopts argon and carbon dioxide as mixed gases for blowing denitrification treatment, and is assisted by cross-arranged blowing pipes, which can greatly reduce the nitrogen content of the alloy liquid; specifically, the carbon dioxide gas can generate double carbon monoxide gas with the carbon in the alloy liquid, and the carbon dioxide gas is beneficial to reducing the surface tension of the bubbles, so that the generated carbon monoxide bubbles are small in volume and more diffusely distributed, and the denitrification effect is better; however, an increase in the amount of carbon dioxide gas introduced will increase the oxygen content in the alloy liquid; by optimizing the ratio of argon and carbon dioxide, while ensuring the reduction of the nitrogen content, the oxygen and hydrogen contents will not be significantly increased, and ultimately the quality of the alloy material is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0018] Figure 1 This is a schematic diagram of air blowing denitrification according to the present invention;

[0019] Figure 2 This is a graph showing the relationship between the volume ratio of argon and carbon dioxide and the nitrogen content and oxygen content of the present invention. DETAILED DESCRIPTION

[0020] The following examples are used to explain the implementation methods of the present application in detail, so that the implementation process of how the present application uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0021] Example 1

[0022] A method for denitrification of alloy liquid by gas blowing, comprising the following steps:

[0023] (1) A mixed gas is introduced into the blowing tube at a flow rate of 50 NL / min in advance; the mixed gas is selected from argon and carbon dioxide, and the volume ratio of argon to carbon dioxide is 10:1.

[0024] (2) Insert the ventilated blowing tube into the lower middle part of the alloy liquid, and as the mixed gas contacts and stirs the alloy liquid, perform vacuum denitrification treatment for 12 minutes.

[0025] The above-mentioned blow pipes include a No. 1 blow pipe and a No. 2 blow pipe, and the No. 1 blow pipe and the No. 2 blow pipe are arranged crosswise, and the angle formed is 40°.

[0026] Example 2

[0027] A method for denitrification of alloy liquid by gas blowing, comprising the following steps:

[0028] (1) A mixed gas is introduced into the blowing tube at a flow rate of 60 NL / min in advance; the mixed gas is selected from argon and carbon dioxide, and the volume ratio of argon to carbon dioxide is 8:1.

[0029] (2) Insert the ventilated blowing tube into the lower middle part of the alloy liquid, and as the mixed gas contacts and stirs the alloy liquid, perform vacuum denitrification treatment for 12 minutes.

[0030] The above-mentioned blow pipes include a No. 1 blow pipe and a No. 2 blow pipe, and the No. 1 blow pipe and the No. 2 blow pipe are arranged crosswise, and the angle formed is 30°.

[0031] Example 3

[0032] A method for denitrification of alloy liquid by gas blowing, comprising the following steps:

[0033] (1) A mixed gas is introduced into the blowing tube at a flow rate of 50 NL / min in advance; the mixed gas is selected from argon and carbon dioxide, and the volume ratio of argon to carbon dioxide is 12:1.

[0034] (2) Insert the ventilated blowing tube into the lower middle part of the alloy liquid, and as the mixed gas contacts and stirs the alloy liquid, perform vacuum denitrification treatment for 12 minutes.

[0035] The above-mentioned blow pipes include a No. 1 blow pipe and a No. 2 blow pipe, and the No. 1 blow pipe and the No. 2 blow pipe are arranged crosswise, and the angle formed is 50°.

[0036] Comparative Example 1

[0037] A method for denitrification of alloy liquid by gas blowing, comprising the following steps:

[0038] (1) Argon gas is introduced into the injection tube at a flow rate of 50 NL / min.

[0039] (2) Insert the ventilated blowing tube into the lower middle part of the alloy liquid, and as the argon gas contacts and stirs the alloy liquid, perform vacuum denitrification treatment for 12 minutes.

[0040] The above-mentioned blow pipes include a No. 1 blow pipe and a No. 2 blow pipe, and the No. 1 blow pipe and the No. 2 blow pipe are arranged crosswise, and the angle formed is 40°.

[0041] Comparative Example 2

[0042] A method for denitrification of alloy liquid by gas blowing, comprising the following steps:

[0043] (1) Carbon dioxide is introduced into the injection pipe at a flow rate of 50 NL / min.

[0044] (2) Insert the ventilated blowing tube into the lower middle part of the alloy liquid, and as the carbon dioxide contacts and stirs the alloy liquid, perform vacuum denitrification treatment for 12 minutes.

[0045] The above-mentioned blow pipes include a No. 1 blow pipe and a No. 2 blow pipe, and the No. 1 blow pipe and the No. 2 blow pipe are arranged crosswise, and the angle formed is 40°.

[0046] Comparative Example 3

[0047] A method for denitrification of alloy liquid by gas blowing, comprising the following steps:

[0048] (1) A mixed gas is introduced into a single blowing tube at a flow rate of 50 NL / min in advance; the mixed gas is selected from argon and carbon dioxide, and the volume ratio of argon to carbon dioxide is 10:1.

[0049] (2) Insert the ventilated blowing tube into the lower middle part of the alloy liquid, and as the mixed gas contacts and stirs the alloy liquid, perform vacuum denitrification treatment for 12 minutes.

[0050] Comparative Example 4

[0051] A method for denitrification of alloy liquid by gas blowing, comprising the following steps:

[0052] (1) A mixed gas is introduced into the blowing tube at a flow rate of 50 NL / min in advance; the mixed gas is selected from argon and carbon dioxide, and the volume ratio of argon to carbon dioxide is 10:1.

[0053] (2) Insert the ventilated blowing tube into the surface of the alloy liquid, and as the mixed gas contacts and stirs the alloy liquid, perform vacuum denitrification treatment for 30 minutes.

[0054] The above-mentioned blow pipes include a No. 1 blow pipe and a No. 2 blow pipe, and the No. 1 blow pipe and the No. 2 blow pipe are arranged crosswise, and the angle formed is 40°.

[0055] Comparative Example 5

[0056] A method for denitrification of alloy liquid by gas blowing, comprising the following steps:

[0057] (1) A mixed gas is introduced into a single blowing tube at a flow rate of 50 NL / min in advance; the mixed gas is selected from argon and carbon dioxide, and the volume ratio of argon to carbon dioxide is 10:1.

[0058] (2) Insert the ventilated blowing tube into the surface of the alloy liquid, and as the mixed gas contacts and stirs the alloy liquid, perform vacuum denitrification treatment for 30 minutes.

[0059] Test results

[0060] 1. The impurity content of the alloy liquid before and after treatment in Examples 1-3 and Comparative Examples 1-5 was tested. The specific results are shown in the following table.

[0061] Table 1 Impurity removal and refining time

[0062]

[0063]

[0064] From the above table, we can see that:

[0065] (1) Compared with Example 1, the nitrogen content of the alloy liquid in Comparative Example 1 is slightly higher, indicating that the combined use of Ar / CO2 can further reduce the nitrogen content of the alloy liquid.

[0066] (2) Compared with Example 1, the liquid nitrogen content of the alloy in Comparative Example 2 did not change significantly, indicating that pure CO2 introduction can also reduce the nitrogen content to a good extent, but the oxygen content increased significantly, affecting the quality of the alloy.

[0067] (3) Compared with Example 1, the nitrogen content in Comparative Example 3 is slightly higher, indicating that the cross-arrangement of the injection pipes is beneficial to improving the denitrification effect.

[0068] (4) The nitrogen content in Comparative Examples 4 and 5 is significantly higher, indicating that compared with surface blowing, middle and lower blowing can better remove nitrogen.

[0069] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for denitrification of alloy liquid by gas blowing, characterized in that: The following steps are involved: (1) Introduce mixed gas into the injection pipe in advance; (2) Insert the ventilated blowing pipe into the lower middle part of the alloy liquid, and as the mixed gas contacts and stirs the alloy liquid, vacuum denitrification treatment is achieved.

2. The method for denitrification of alloy liquid by gas blowing according to claim 1, characterized in that: In step (1), the blow pipe includes a No. 1 blow pipe and a No. 2 blow pipe, and the No. 1 blow pipe and the No. 2 blow pipe are arranged crosswise.

3. The method for denitrification of alloy liquid by gas blowing according to claim 2, characterized in that: The angle formed between the No. 1 blowing pipe and the No. 2 blowing pipe is 30-50°.

4. The method for denitrification of alloy liquid by gas blowing according to claim 1, characterized in that: In step (1), the mixed gas is selected from argon and carbon dioxide, and the volume ratio of argon to carbon dioxide is (8-12):

1.

5. The method for denitrification of alloy liquid by gas blowing according to claim 4, characterized in that: The volume ratio of the argon gas to the carbon dioxide is 10:

1.

6. The method for denitrification of alloy liquid by gas blowing according to claim 1, characterized in that: In step (1), the flow rate of the mixed gas is 50-60NL / min.

7. The method for denitrification of alloy liquid by gas blowing according to claim 1, characterized in that: In step (2), the initial oxygen content of the alloy liquid is 0.02%, the initial hydrogen content is 0.001%, and the initial nitrogen content is 0.012%.

8. The method for denitrification of alloy liquid by gas blowing according to claim 1, characterized in that: In step (2), the vacuum denitrification treatment time is 12-30 minutes.

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