CN114457210A - Method for controlling purity of tundish molten steel during ladle changing period - Google Patents
Method for controlling purity of tundish molten steel during ladle changing period Download PDFInfo
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- CN114457210A CN114457210A CN202111596144.4A CN202111596144A CN114457210A CN 114457210 A CN114457210 A CN 114457210A CN 202111596144 A CN202111596144 A CN 202111596144A CN 114457210 A CN114457210 A CN 114457210A
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- tundish
- molten steel
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/072—Treatment with gases
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Abstract
The invention discloses a method for controlling the molten steel purity of a tundish during ladle change, wherein mixed gas of argon and natural gas is injected into the tundish after the previous ladle finishes molten steel injection, molten steel is injected into the tundish by the next ladle, the tonnage rising speed of the tundish is controlled, and the mixed gas is stopped to be introduced after the tonnage of the tundish is stabilized; residual oxygen in the tundish is consumed by combustion of natural gas, and the molten steel is sealed and protected by argon, so that the molten steel and oxygen in the air are prevented from secondary oxidation. The invention has the advantages that in the continuous casting process, the tonnage rising speed of the tundish is controlled and the mixed gas of argon and natural gas is injected into the tundish when the ladle is changed, so that the slag entrapment of molten steel in the tundish is reduced, the secondary oxidation of the molten steel is avoided, the floating of inclusions in the tundish is promoted, and the purity of the molten steel of the mixed blank of the ladle change is improved.
Description
Technical Field
The invention belongs to the technical field of tundishes, and particularly relates to a method for controlling the purity of molten steel in a tundish during ladle change.
Background
The continuous casting process is a process in which liquid molten steel is cast, condensed, and cut to obtain a cast slab. The main link of the process is that one or more furnaces of molten steel are continuously and stably injected into a crystallizer through a tundish, the crystallizer consists of four copper plates with water tanks, the molten steel enters the crystallizer and is cooled by the copper plates to form a solid blank shell with target requirements, a casting blank is further solidified through a secondary cooling area after being discharged from the crystallizer, and the casting blank is drawn out of a continuous casting machine through the supporting and rotating action of rollers in a blank drawing straightening device. And cutting the blank into a set length by a cutting device. The tundish is an important device for maintaining continuous casting of molten steel in the continuous casting process, and when the ladle is replaced, the molten steel contained in the tundish is continuously and stably injected into the crystallizer until new molten steel is injected into the tundish after the ladle filled with the molten steel is replaced. The defects are that in the continuous casting process, when steel ladles exchange and impact steel, molten steel is exposed, molten steel impacts a tundish to generate a large amount of stirring, and the molten steel mixing part of the two ladles generates secondary oxidation and slag entrapment; in the process of the tonnage rise of the tundish, the molten steel flow field in the tundish is disordered, the molten steel generates secondary oxidation and slag entrapment, and the quality of the corresponding mixed blank is poorer than that of the normal blank.
Disclosure of Invention
1. Technical problem to be solved
Aiming at the problems that in the prior art, in the continuous casting process, molten steel is exposed when steel ladles exchange and impact steel, a large amount of stirring is generated when a steel flow impacts a tundish, and secondary oxidation and slag entrapment are generated at the mixed part of the molten steel of the two ladles; the invention aims to provide a method for controlling the purity of molten steel in a tundish during ladle change, which solves the problems that the quality of a corresponding mixed blank is poorer than that of a normal blank and the like in the process of increasing the tonnage of the tundish, the molten steel flow field in the tundish is disordered, and the molten steel generates secondary oxidation and slag entrapment, and the quality of the molten steel of the tundish is poorer than that of the normal blank.
2. Technical scheme
A method for controlling the purity of molten steel in a tundish during ladle changing of a ladle is characterized by comprising the following operations: injecting mixed gas of argon and natural gas into the tundish after the previous steel ladle finishes the molten steel injection, injecting the molten steel into the tundish by the next steel ladle, controlling the tonnage rising speed of the tundish, and stopping introducing the mixed gas after the tonnage of the tundish is stable; residual oxygen in the tundish is consumed by combustion of natural gas, and the molten steel is sealed and protected by argon, so that the molten steel and oxygen in the air are prevented from secondary oxidation.
Further, the partial pressure of the natural gas in the mixed gas of argon and natural gas and the partial pressure of argon satisfy the following relation: the natural gas partial pressure is 0.6278+0.3430 argon partial pressure.
Further, the relationship between the natural gas flow and the argon gas flow in the mixed gas of argon and natural gas satisfies the following relational expression: natural gas flow-17.29 +0.06206 argon gas flow.
Furthermore, the maximum molten steel capacity of the tundish is 30 tons, and the tonnage of the tundish is 20-22 tons before molten steel is injected into the tundish after the tundish is replaced.
Furthermore, the ton rising speed of the tundish is 1.5-2.0 tons/min.
And further, injecting molten steel into the tundish after the ladle is replaced, and stopping introducing mixed gas of argon and natural gas when the maximum tonnage rise of the tundish is 28-30 tons and the tonnage of the tundish is stable.
Further, the partial pressure of argon in the mixed gas of argon and natural gas is 4.0Bar, and the partial pressure of natural gas is 2.0 Bar; the gas flow of the mixed gas of the argon and the natural gas is 600L/min of the argon and 20L/min of the natural gas.
Further, the mixed gas of argon and natural gas is injected into the tundish through a gas pipeline, the gas pipeline is arranged on the tundish cover plate, the gas pipeline is provided with a plurality of gas outlets, and the plurality of gas outlets are uniformly distributed.
When the steel ladle is changed and the next steel ladle starts to inject molten steel, the tonnage of the tundish is 20-22 tons, and the rising speed of the tundish ton is controlled: 1.5-2.0 tons/min, and increasing the tonnage of the tundish to 28-30 tons, controlling the increasing speed of the tonnage of the tundish to reduce the stirring of molten steel flow in the tundish, and avoiding the secondary oxidation and slag entrapment of the mixed part of the molten steel of the two ladles; by injecting mixed gas of argon and natural gas into the tundish, the natural gas burns and consumes residual oxygen in the tundish, the argon carries out sealing protection on the molten steel, secondary oxidation caused by triggering of oxygen in the molten steel and air is prevented, and the purity of the molten steel of a mixed blank during ladle exchange is improved; meanwhile, when the natural gas is combusted, micro negative pressure is generated in the tundish, so that oxygen dissolved in the molten steel is separated out from the molten steel and is consumed by the combusted natural gas.
3. Advantageous effects
Compared with the prior art, the invention has the beneficial effects that: in the continuous casting process, the tonnage rising speed of the tundish is controlled and the mixed gas of argon and natural gas is injected into the tundish when the ladle is changed, so that the slag entrapment of molten steel in the tundish is reduced, the secondary oxidation of the molten steel is avoided, the floating of inclusions in the tundish is promoted, and the purity of the molten steel of a mixed blank of the ladle is improved.
Drawings
The invention is further described below with reference to the accompanying drawings.
FIG. 1 is a front view of the tundish cover according to the present invention.
FIG. 2 is a schematic bottom view of the tundish cover of the present invention.
In the figure: 1-a gas pipeline; 2-tundish cover plate; 3-gas outlet.
Detailed Description
The present invention is further illustrated by the following specific examples.
A method for controlling the purity of molten steel in a tundish during ladle changing of a ladle is characterized by comprising the following operations: the mixed gas of argon and natural gas is injected into the tundish after the last steel ladle finishes the molten steel injection, the partial pressure of argon is 4.0Bar in the mixed gas of argon and natural gas, the partial pressure of natural gas is 2.0Bar, and the partial pressure relation of natural gas and argon in the mixed gas of argon and natural gas satisfies the following relational expression: natural gas partial pressure 0.6278+0.3430 argon partial pressure; the gas flow of the mixed gas of argon and natural gas is 600L/min of argon and 20L/min of natural gas, and the relationship between the gas flow of the natural gas and the gas flow of the argon in the mixed gas of argon and natural gas meets the following relational expression: natural gas flow-17.29 +0.06206 argon gas flow; after the steel ladle is changed, before the molten steel is injected into the tundish, the tonnage of the tundish is 20-22 tons, the molten steel is injected into the tundish, the ascending speed of the tonnage of the tundish is 1.5-2.0 tons/min, the ascending maximum value of the tonnage of the tundish is 28-30 tons, after the tonnage of the tundish is stable, mixed gas of argon and natural gas is stopped being introduced into the tundish, the natural gas burns to consume residual oxygen in the tundish, and the argon carries out sealing protection on the molten steel to prevent the molten steel and oxygen in the air from starting secondary oxidation.
As shown in fig. 1 and 2, a mixed gas of argon and natural gas is injected into a tundish through a gas pipe 1, the gas pipe 1 is arranged on a tundish cover plate 2, the gas pipe 1 is provided with a plurality of gas nozzles 3, the gas nozzles 3 are uniformly distributed, and (i), (ii), (iii), (iv), (v), (c) and c,
all of which are gas ejection ports 3. Requirements of the gas pipeline 1: high temperature resistance, and the thermal expansion can not cause the cracking of the clad refractory material, and the smoothness of the pipeline is ensured.
The continuous casting billet obtained during the ladle changing period is called a mixed billet, the quality of the mixed billet is different from that of a normal intermediate billet, and the occurrence rate of steel inclusion defects in the process of manufacturing the mixed billet is high, mainly because a covering agent of the intermediate ladle, ladle drainage sand and furnace slag are mixed into the next ladle; in this embodiment, when the next ladle starts to inject molten steel, the tonnage of the tundish is 20 to 22 tons, and the rise speed of the tundish ton is controlled: 1.5-2.0 tons/min, and increasing the tonnage of the tundish to 28-30 tons, controlling the increasing speed of the tonnage of the tundish to reduce the stirring of molten steel flow in the tundish, and avoiding the secondary oxidation and slag entrapment of the mixed part of the molten steel of the two ladles; ladle exchange, through tundish shroud) inner vent body is sealed, molten steel reoxidation when preventing ladle change, the sealed tundish principle of argon gas and natural gas:
at 1.1,500 deg.C, O2Equilibrium partial pressure of 7.9X10-15Under the precondition of atm,dissolution of 304 molten steel [ O ]]Was 30 ppm.
Introducing mixed gas of argon and 3.5 percent of natural gas into the tundish, and sealing the molten steel;
CH4+3/2O2＝CO+2H2O；
2. combustion of natural gas, O2Consumption → O in tundish2Partial pressure is as follows: 10-20.5atm, dissolving in steel [ O ]]And the secondary oxidation of the molten steel is avoided.
The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the present invention pertains, the architecture form can be flexible and varied without departing from the concept of the present invention, and a series of products can be derived. But rather a number of simple derivations or substitutions are made which are to be considered as falling within the scope of the invention as defined by the appended claims.
Claims (8)
1. A method for controlling the purity of molten steel in a tundish during ladle change is characterized by comprising the following operations: and after the previous steel ladle finishes the molten steel injection, injecting mixed gas of argon and natural gas into the tundish, injecting the molten steel into the tundish by the next steel ladle, controlling the tonnage rising speed of the tundish, and stopping introducing the mixed gas after the tonnage of the tundish is stabilized.
2. The method of claim 1, wherein the method further comprises the step of: the relationship between the partial pressure of the natural gas in the mixed gas of the argon and the natural gas and the partial pressure of the argon satisfies the following relational expression: the natural gas partial pressure is 0.6278+0.3430 argon partial pressure.
3. The method of claim 2, wherein the method further comprises the step of controlling the purity of the molten steel in the tundish during ladle change: the relationship between the natural gas flow and the argon gas flow in the mixed gas of the argon gas and the natural gas meets the following relational expression: natural gas flow-17.29 +0.06206 argon gas flow.
4. The method of claim 3, wherein the method further comprises the step of controlling the purity of the molten steel in the tundish during ladle change: the maximum molten steel capacity of the tundish is 30 tons, and the tonnage of the tundish is 20-22 tons before molten steel is injected into the tundish after the tundish is replaced.
5. The method of claim 4, wherein the method further comprises the step of controlling the purity of the molten steel in the tundish during ladle change: the ton lifting speed of the tundish is 1.5-2.0 tons/min.
6. The method of claim 5, wherein the method further comprises the step of: and injecting molten steel into the tundish after the ladle is replaced, and stopping introducing mixed gas of argon and natural gas when the maximum tonnage rise of the tundish is 28-30 tons and the tonnage of the tundish is stable.
7. The method of claim 6, wherein the method further comprises the step of: the partial pressure of argon in the mixed gas of argon and natural gas is 4.0Bar, and the partial pressure of natural gas is 2.0 Bar; the gas flow of the mixed gas of the argon and the natural gas is 600L/min of the argon and 20L/min of the natural gas.
8. The method of controlling the purity of the molten steel in the tundish during ladle change according to any one of claims 1 to 7, wherein: the mixed gas of the argon and the natural gas is injected into the tundish through a gas pipeline, the gas pipeline is arranged on the tundish cover plate, the gas pipeline is provided with a plurality of gas nozzles, and the plurality of gas nozzles are uniformly distributed.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111596144.4A CN114457210A (en) | 2021-12-24 | 2021-12-24 | Method for controlling purity of tundish molten steel during ladle changing period |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202111596144.4A CN114457210A (en) | 2021-12-24 | 2021-12-24 | Method for controlling purity of tundish molten steel during ladle changing period |
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| CN114457210A true CN114457210A (en) | 2022-05-10 |
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4062397A (en) * | 1976-03-16 | 1977-12-13 | Cashdollar Sr Robert E | Protection against oxidation of molten metal streams in continuous casting |
| WO1996001709A1 (en) * | 1994-07-08 | 1996-01-25 | Ipsco Inc. | Dual tundishes for use with twin-roll caster |
| CN202270967U (en) * | 2011-09-02 | 2012-06-13 | 鞍钢股份有限公司 | Flocculation-preventing breathable upper nozzle of tundish |
| CN111168024A (en) * | 2020-02-11 | 2020-05-19 | 首钢集团有限公司 | Device and method for preventing molten steel from being secondarily oxidized in ladle changing process |
| CN111822665A (en) * | 2020-07-25 | 2020-10-27 | 莱芜钢铁集团银山型钢有限公司 | Argon blowing control method and argon control device for continuous casting tundish breathable upper nozzle pocket block |
| CN113600773A (en) * | 2021-07-30 | 2021-11-05 | 南京钢铁股份有限公司 | Pouring process of low-oxygen-concentration continuous casting tundish |
-
2021
- 2021-12-24 CN CN202111596144.4A patent/CN114457210A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4062397A (en) * | 1976-03-16 | 1977-12-13 | Cashdollar Sr Robert E | Protection against oxidation of molten metal streams in continuous casting |
| WO1996001709A1 (en) * | 1994-07-08 | 1996-01-25 | Ipsco Inc. | Dual tundishes for use with twin-roll caster |
| CN202270967U (en) * | 2011-09-02 | 2012-06-13 | 鞍钢股份有限公司 | Flocculation-preventing breathable upper nozzle of tundish |
| CN111168024A (en) * | 2020-02-11 | 2020-05-19 | 首钢集团有限公司 | Device and method for preventing molten steel from being secondarily oxidized in ladle changing process |
| CN111822665A (en) * | 2020-07-25 | 2020-10-27 | 莱芜钢铁集团银山型钢有限公司 | Argon blowing control method and argon control device for continuous casting tundish breathable upper nozzle pocket block |
| CN113600773A (en) * | 2021-07-30 | 2021-11-05 | 南京钢铁股份有限公司 | Pouring process of low-oxygen-concentration continuous casting tundish |
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