CN110684881A

CN110684881A - Decarburization method for carrying out multi-gas injection through oxygen lance

Info

Publication number: CN110684881A
Application number: CN201911046009.5A
Authority: CN
Inventors: 李龙; 王建
Original assignee: Pangang Group Panzhihua Iron and Steel Research Institute Co Ltd
Current assignee: Pangang Group Panzhihua Iron and Steel Research Institute Co Ltd
Priority date: 2019-10-30
Filing date: 2019-10-30
Publication date: 2020-01-14
Anticipated expiration: 2039-10-30
Also published as: CN110684881B

Abstract

The invention discloses a decarburization method for carrying out multi-gas injection through an oxygen lance, which comprises the following steps: 1) CO supply is arranged on RH vacuum treatment equipment₂-an argon blowing pipe and an oxygen lance for an Ar gas mixture; 2) inserting RH vacuum treatment equipment into a ladle filled with molten steel, starting a vacuum pump to ensure that the vacuum of the RH vacuum treatment equipment is pumped to be less than a first pressure, and starting blowing CO₂-Ar gas mixture circulating molten steel; 3) blowing CO₂Blowing a first gas into the molten steel by using an oxygen lance while using the Ar mixed gas; 4) the vacuum pump makes the RH vacuum processing equipment vacuumized to be less than the second pressure, and then the CO supply is stopped₂-Ar mixed gas and the argon blowing tube starts supplying a second gas so that molten steel circulates; 5) and when the vacuum of the RH vacuum processing equipment is pumped to be lower than the third pressure by the vacuum pump, continuously supplying the first gas and the second gas for 5-8 min. The decarburization method using an oxygen lance for multiple gas injection of the present invention is carried out using an oxygen lanceWhen gas is sprayed, the end point carbon content is less than 10ppm, and the smelting time is shortened by 3-4 min.

Description

Decarburization method for carrying out multi-gas injection through oxygen lance

Technical Field

The present invention relates to the field of metallurgy, and more particularly, to a decarburization method with multiple gas injection through an oxygen lance.

Background

In recent years, RH vacuum degassing equipment, and RH functions and steel types for refining have been expanded, and a multifunctional vacuum refining technology has been developed, and has been dominant in external refining. Most steel mills are provided with RH refining equipment, so that the high-efficiency and low-cost production of high-quality steel is realized.

Along with the requirement of the market on the carbon content of various steels, particularly the carbon content of finished products is within 15ppm or even 10ppm, in order to meet the requirement, RH adopts oxygen blowing to perform forced decarburization, the oxygen supply time needs to be prolonged, so that the oxygen activity of molten steel is higher, and the cleanliness of the molten steel is not favorable.

In the prior art, through holes are arranged on the lower pipe wall of an RH ascending/descending pipe, and CO is blown into molten steel through a spray pipe during RH refining₂Blowing CaCO into molten steel by using gas, or gas of nitrogen, argon, carbon dioxide or carbon monoxide as carrier₃、BaCO₃、MgCO₃、NaCO₃、FeO、Fe₂O₃Or one or more than one powder in MnO, the decarburization reaction efficiency is promoted, and the carbon content in the molten steel is further reduced. The adoption of blowing/adding of oxidizing powder can easily cause larger temperature drop of molten steel, and on the other hand, the change of top slag composition can influence the cleanliness of molten steel.

In the prior art, a heating agent (metal Al/Si) is added in the vacuum decarburization process, and oxygen is supplied by a top lance to heat molten steel and accelerate the decarburization speed. However, this increases the Al/Si consumption, which is not good for reducing the production cost.

Therefore, there is still a need for a method of decarburization at a low cost, quickly and efficiently.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a decarburization method for carrying out multi-gas injection through an oxygen lance.

Based on the purpose, the following technical scheme is adopted:

according to the present invention, there is provided a decarburization method using an oxygen lance for multiple gas injection, comprising the steps of:

1) CO supply is arranged on RH vacuum treatment equipment₂-an argon blowing pipe and an oxygen lance for an Ar gas mixture;

2) inserting RH vacuum treatment equipment into a ladle filled with molten steel, starting a vacuum pump to ensure that the vacuum of the RH vacuum treatment equipment is pumped to be less than a first pressure, and starting blowing CO₂-Ar gas mixture circulating molten steel;

3) blowing CO₂Blowing a first gas into the molten steel by using an oxygen lance while using the Ar mixed gas;

4) the vacuum pump makes the RH vacuum processing equipment vacuumized to be less than the second pressure, and then the CO supply is stopped₂Ar mixed gas and the argon blowing pipe starts to supply second gas to circulate the molten steel, and the oxygen lance still supplies the first gas;

5) and when the vacuum of the RH vacuum processing equipment is pumped to be lower than the third pressure by the vacuum pump, continuously supplying the second gas and the first gas for 5-8 min.

Further, the carbon content of the molten steel to be treated is 0.06-0.08 wt%, the oxygen content is 0.04-0.050 wt%, and the temperature is 1650-1700 ℃.

Further, CO₂CO in-Ar gas mixture₂50-65 wt% of CO₂The flow rate of the-Ar mixture is 0.7-1.2Nm³/h·t。

Further, the first gas is CO₂-O₂And (4) mixing the gases.

Further, CO₂-O₂CO in mixed gas₂15 to 25 weight percent of CO₂-O₂The air supply intensity of the mixed gas is 8-12 Nm³/h·t。

Further, the first gas is O₂。

Further, O₂The air supply intensity of (1) is 8-12 Nm³/h·t。

Further, the second gas is Ar-H₂And (4) mixing the gases.

Further, Ar-H₂H in the mixed gas₂55 to 70 weight percent of Ar-H₂The flow rate of the mixed gas is 0.7-1.2Nm³/h·t。

Further, the second gas is Ar gas.

Further, the first pressure was 17 kPa.

Further, the second pressure is 300 Pa.

Further, the second pressure is 100 Pa.

The invention has the beneficial effects that:

the decarburization method for multi-gas injection through the oxygen lance can realize that the end point carbon content is less than 10ppm and the smelting time is shortened by 3-4min when the oxygen lance is used for injecting gas.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are required to be used in the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some implementation examples of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.

FIG. 1 is a schematic view of an RH vacuum processing apparatus according to embodiments 1 to 4 of the present invention;

FIG. 2 is a schematic view of an argon blowing tube according to an embodiment of the present invention;

FIG. 3 is a schematic view of the projection of the argon blowing tube and the rising pipe to the horizontal plane according to the embodiment of the present invention.

List of reference numerals

1-steel ladle 2-vacuum degassing tank 3-tank body 4-downcomer 5-riser 7-oxygen lance 8-argon blowing pipe 81-main pipe 82-first branch pipe 83-second branch pipe

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the following embodiments of the present invention are described in further detail with reference to the accompanying drawings.

Examples 1 to 4 the RH vacuum processing apparatus used in examples 1 to 4 is shown in fig. 1, 2 and 3 and includes:

the device comprises a steel ladle 1, a vacuum degassing tank 2 inserted into the steel ladle 1, an oxygen lance 7, an argon blowing pipe 8 and an air pumping through hole for vacuumizing the vacuum degassing tank 2;

the vacuum degassing tank 2 comprises a tank body 3, a downcomer 4 and an ascending pipe 5, wherein the downcomer 4 and the ascending pipe 5 are arranged at the bottom of the tank body 3 and are communicated with the tank body 3; the downcomer 4 and the riser 5 are arranged side by side.

The oxygen lance 7 is inserted into the tank body 3 from the top of the vacuum degassing tank 2; and

the argon blowing pipe 8 is arranged on the ascending pipe 5 and is communicated with the ascending pipe 5;

wherein, the argon blowing pipe 8 comprises a main pipe 81, a first branch pipe 82 and a second branch pipe 83 which are divided into two paths at the tail end of the main pipe 81; the first branch pipe 82 and the second branch pipe 83 communicate with the rising pipe 5. The first branch pipe 82 and the second branch pipe 83 are arranged offset, and the second branch pipe 83 is located below the first branch pipe 82. In the projection shown in fig. 3, the angle R between the first branch pipe 82 and the second branch pipe 83 is 10-25 degrees, and the angle R is the angle formed by the connection line of the first branch pipe 82 and the second branch pipe 83 with the center O of the rising pipe 5. As shown in the schematic view of the argon blowing tube shown in fig. 2, a horizontal direction (indicated by an arrow) is defined, and the second branch tube 82 is inclined downward at an angle of 5 to 15 degrees from the horizontal direction. Therefore, gas blown out of the argon blowing pipe 8 is disturbed from the bottom end of the ascending pipe 5, so that the disturbance of the gas on the molten steel is more sufficient, and the second branch pipe 82 is inclined downwards at an angle of only 5-15 degrees from the horizontal direction, so that the gas cannot be excessively blown downwards, and the disturbance strength is ensured.

The second branch pipe is arranged at one quarter of the distance from the bottom end of the ascending pipe.

The argon blowing pipe 8 is a stainless steel pipe.

Example 1

The molten steel to be treated meets the following requirements: the carbon content is 0.06 wt% -0.08 wt%, the oxygen content is 0.04 wt% -0.05 wt%, and the temperature is 1650-.

When the ladle is placed at the RH treatment station, the dip pipe is inserted into the molten steel of the ladle, and the vacuum pump is started to pump air. When the pressure in the vacuum degassing tank is less than 17kPa, CO is supplied through the argon blowing pipe₂The mixed gas of-Ar is used as circulating gas and reaction medium, and CO is contained in the mixed gas₂The content of 51 wt% and the gas supply intensity of 0.9Nm³T, using CO at high temperature₂Weak oxidation of the gas, reaction occurs: [ C ]]+CO ₂2 CO. On the one hand, direct decarbonization of CO₂The reaction is promoted by reducing the partial pressure of CO in the Ar-mixed gas. On the other hand, twice of CO is generated, and the circulation flow is increased to accelerate the decarburization. At the same time, the oxygen lance injects CO₂-O₂Mixed gas, CO in mixed gas₂The content is 20 wt%, and the gas supply intensity is 8Nm³/h·t。When the pressure in the vacuum degassing tank is less than 300Pa, switching to Ar-H₂Driven by mixed gas, H in the mixed gas₂The content is 65 wt%, and the gas supply intensity is 1.2Nm³H.t. And further decarbonizing for 8min under the pressure of less than 100Pa in the vacuum degassing tank. The end point carbon content can be 9ppm, and the smelting time is shortened by 4 min.

Example 2

When the ladle is placed at the RH treatment station, the dip pipe is inserted into the molten steel of the ladle, and the vacuum pump is started to pump air. When the pressure in the vacuum degassing tank is less than 17kPa, CO is supplied through the argon blowing pipe₂The mixed gas of-Ar is used as circulating gas and reaction medium, and CO is contained in the mixed gas₂The content is 65 wt%, and the gas supply intensity is 1.2Nm³T, using CO at high temperature₂Weak oxidation of the gas, reaction occurs: [ C ]]+CO ₂2 CO. On the one hand, direct decarbonization of CO₂The reaction is promoted by reducing the partial pressure of CO in the Ar-mixed gas. On the other hand, twice of CO is generated, and the circulation flow is increased to accelerate the decarburization. At the same time, the oxygen lance injects CO₂-O₂Mixed gas, CO in mixed gas₂Content 15 wt%, gas supply intensity 12Nm³H.t. When the pressure in the vacuum degassing tank is less than 300Pa, switching to Ar-H₂Driven by mixed gas, H in the mixed gas₂The content is 55 wt%, and the gas supply intensity is 0.7Nm³H.t. The pressure in the vacuum degassing tank is less than 100Pa for further decarburization for 7 min. The end point carbon content can be 10ppm, and the smelting time is shortened by 3 min.

Example 3

When the ladle is placed at the RH treatment station, the dip pipe is inserted into the molten steel of the ladle, and the vacuum pump is started to pump air. When the pressure in the vacuum degassing tank is less than 17kPa, CO is supplied through the argon blowing pipe₂The mixed gas of-Ar is used as circulating gas and reaction medium, and CO is contained in the mixed gas₂The content is 50 wt%, and the gas supply intensity is 0.7Nm³H.t. Using CO at high temperature₂Weak oxidation of the gas, reaction occurs: [ C ]]+CO ₂2 CO. On the one hand, direct decarbonization of CO₂The reaction is promoted by reducing the partial pressure of CO in the Ar-mixed gas. On the other hand, twice of CO is generated, and the circulation flow is increased to accelerate the decarburization. At the same time, the oxygen lance injects O₂Gas, gas supply intensity is 12Nm³H.t. When the pressure in the vacuum degassing tank is less than 300Pa, the operation is switched to Ar gas drive, and the gas supply intensity is 0.7Nm³H.t. And further decarbonizing for 5min under the pressure of less than 100Pa in the vacuum degassing tank. The end point carbon content can be 10ppm, and the smelting time is shortened by 4 min.

Example 4

When the ladle is placed at the RH treatment station, the dip pipe is inserted into the molten steel of the ladle, and the vacuum pump is started to pump air. When the pressure in the vacuum degassing tank is less than 17kPa, CO is supplied through the argon blowing pipe₂The mixed gas of-Ar is used as circulating gas and reaction medium, and CO is contained in the mixed gas₂The content is 65 wt%, and the gas supply intensity is 1.2Nm³H.t. Using CO at high temperature₂Weak oxidation of the gas, reaction occurs: [ C ]]+CO ₂2 CO. On the one hand, direct decarbonization of CO₂The reaction is promoted by reducing the partial pressure of CO in the Ar-mixed gas. On the other hand, twice of CO is generated, and the circulation flow is increased to accelerate the decarburization. At the same time, the oxygen lance injects O₂Gas, gas supply intensity is 8Nm³H.t. When the pressure in the vacuum degassing tank is less than 300Pa, the operation is switched to Ar gas drive, and the gas supply intensity is 0.7Nm³H.t. The pressure in the vacuum degassing tank is less than 100Pa for further decarburization for 7 min. The end point carbon content can be 10ppm, and the smelting time is shortened by 4 min.

The foregoing is an exemplary embodiment of the present disclosure, but it should be noted that various changes and modifications could be made herein without departing from the scope of the present disclosure as defined by the appended claims. Furthermore, although elements of the disclosed embodiments of the invention may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated.

It should be understood that, as used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly supports the exception. It should also be understood that "and/or" as used herein is meant to include any and all possible combinations of one or more of the associated listed items.

The numbers of the embodiments disclosed in the embodiments of the present invention are merely for description, and do not represent the merits of the embodiments.

Those of ordinary skill in the art will understand that: the discussion of any embodiment above is meant to be exemplary only, and is not intended to intimate that the scope of the disclosure, including the claims, of embodiments of the invention is limited to these examples; within the idea of an embodiment of the invention, also technical features in the above embodiment or in different embodiments may be combined and there are many other variations of the different aspects of an embodiment of the invention as described above, which are not provided in detail for the sake of brevity. Therefore, any omissions, modifications, substitutions, improvements, and the like that may be made without departing from the spirit and principles of the embodiments of the present invention are intended to be included within the scope of the embodiments of the present invention.

Claims

1. A decarburization method using an oxygen lance for multiple gas injection, which is characterized by comprising the following steps:

4) the vacuum pump makes the RH vacuum processing equipment vacuumized to be less than the second pressure, and then the CO supply is stopped₂-Ar mixed gas and the argon blowing tube starts supplying a second gas so that molten steel circulates;

5) and when the vacuum of the RH vacuum processing equipment is pumped to be lower than the third pressure by the vacuum pump, continuously supplying the first gas and the second gas for 5-8 min.

2. The decarburization method using multiple gas injection through an oxygen lance as claimed in claim 1, wherein the molten steel to be treated has a carbon content of 0.06 wt.% to 0.08 wt.%, an oxygen content of 0.04 wt.% to 0.050 wt.%, and a temperature of 1650-1700 ℃.

3. The decarburization method using multiple gas injection via an oxygen lance as recited in claim 1, wherein CO is introduced into the furnace through the oxygen lance₂CO in-Ar gas mixture₂50-65 wt% of CO₂The flow rate of the-Ar mixture is 0.7-1.2Nm³/h·t。

4. The method of decarbonization by multi-gas injection through an oxygen lance of claim 1 wherein the first gas is CO₂-O₂And (4) mixing the gases.

5. The decarburization method using multiple gas injection through an oxygen lance as recited in claim 4, wherein CO is introduced into the oxygen lance₂-O₂CO in mixed gas₂15 to 25 weight percent of CO₂-O₂The air supply intensity of the mixed gas is 8-12 Nm³/h·t。

6. The decarburization method using multiple gas injection via an oxygen lance as claimed in claim 1, wherein the first gas is O₂。

7. The decarburization method using multiple gas injection via an oxygen lance as recited in claim 6, wherein O is introduced into the oxygen lance₂The air supply intensity of (1) is 8-12 Nm³/h·t。

8. The decarburization method using multiple gas injection via an oxygen lance as claimed in claim 1, wherein the second gas is Ar-H₂And (4) mixing the gases.

9. The process of claim 8A decarburization method using an oxygen lance with multiple gas blasts, characterized in that Ar-H₂H in the mixed gas₂55 to 70 weight percent of Ar-H₂The flow rate of the mixed gas is 0.7-1.2Nm³/h·t。

10. The decarburization method using multiple gas injection via an oxygen lance as claimed in claim 1, wherein the second gas is Ar gas.