CN112226582A - Method for deeply purifying molten steel by RH refining - Google Patents
Method for deeply purifying molten steel by RH refining Download PDFInfo
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- CN112226582A CN112226582A CN202010867635.7A CN202010867635A CN112226582A CN 112226582 A CN112226582 A CN 112226582A CN 202010867635 A CN202010867635 A CN 202010867635A CN 112226582 A CN112226582 A CN 112226582A
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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
- C21C7/10—Handling in a vacuum
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Abstract
The invention discloses a method for deeply purifying molten steel by RH refining, relating to the technical field of steel smelting, in the deep degassing period of the molten steel, CO is sprayed to the molten steel in a vacuum chamber by a top-blown gas plasma spray gun2Plasma, adjusting plasma arc to aim at RH downcomer, performing heat compensation on molten steel, increasing the flow of lift gas, adjusting potential and gun position to determine the flame distance of plasma, and utilizing CO2The plasma arc blows molten steel for 3-8 min; in the high-efficiency inclusion removing period, the control system adds alloy to the RH vacuum chamber based on the data information when the previous stage is finished, and top-blown CO is2And rapidly switching to top-blown Ar plasma, reducing the flow, aligning a plasma spray gun to the RH downcomer, adjusting the potential and the gun position to determine the flame distance of the plasma, further spraying the Ar plasma for 5-10 min, and finally finishing the refining task. Solves the technical problems of limited molten steel cleanliness, slow production rhythm and the like in the existing RH refining process.
Description
Technical Field
The invention relates to the technical field of steel smelting, in particular to a method for deeply purifying molten steel by RH refining.
Background
After the gas is ionized, the collection of electrons and particles, generally in an electrically neutral state, is called a plasma, and generally contains photons, electrons, ground state atoms or molecules, excited state atoms or molecules, and positive and negative ions. The non-equilibrium characteristics of high electron energy and low ion and gas temperature possessed by the non-thermal equilibrium cold plasma are very effective for chemical reaction, on one hand, electrons have enough high energy to excite, dissociate and ionize reactant molecules, on the other hand, the reaction system can be kept at low temperature or even close to room temperature, so that the energy consumption of the reaction system is reduced, and the investment can be saved. Plasma chemistry takes advantage of this property to activate reactants at lower temperatures to carry out reactions that are thermodynamically impossible at ambient temperatures. The low-temperature plasma technology is widely applied to the chemical and chemical fields, such as ozone preparation, ammonia synthesis, methane conversion, hydrocyanic acid synthesis, carbon material preparation, material surface treatment and the like.
At present, the RH vacuum degassing method has been developed from dehydrogenation treatment in 50 years into a refining method with a plurality of metallurgical functions of dehydrogenation, deoxidation, decarburization, desulfurization, dephosphorization and the like, and becomes an external refining device which is most widely applied in the world. It has obvious effects on improving the quality of molten steel, reducing cost and the like, and is suitable for mass production of pure steel. Generally speaking, the RH refining needs to increase the lift gas flow for further dehydrogenation and denitrification, so as to enhance stirring and promote degassing, and then the method has a great limitation condition, on one hand, the increase of the lift gas flow is easy to form an 'air column' in a riser, and on the other hand, the RH stirring effect is influenced; on the other hand, promote the increase of gas flow and certainly lead to the molten steel temperature drop bigger, be unfavorable for making the better sediment of mobility, influence the seizure of inclusion, be difficult to match the continuous casting process simultaneously. Meanwhile, the normal Ar blowing cannot generate uniformly dispersed micro bubbles in the whole RH, and has limitations on the dehydrogenation and denitrification of molten steel and the removal of inclusions.
Chinese patent ZL201810230019.3 discloses a VD furnace utilizing CO2Method for denitrogenation in steel making, which method utilizes CO2The excellent metallurgical characteristics enhance the denitrification and purification of molten steel, however, due to CO2The heat absorption reaction with carbon element in the molten steel will cause larger temperature drop of the molten steel and influence the matching with the continuous casting process.
Therefore, how to strengthen the stirring intensity of a molten pool in the RH refining process, deeply purify molten steel, shorten refining time and break through the limit of cleanliness of the traditional process becomes a difficult problem to be solved urgently in the steel industry.
Disclosure of Invention
In order to solve the technical problems, the invention provides a method for deeply purifying molten steel by RH refining, the RH vacuum refining process comprises 2 stages of a molten steel deep degassing period and an efficient inclusion removing period,
in the deep degassing period of the molten steel, the control system sets top-blown CO based on the components of RH station-entering molten steel2Flow rate, spraying CO to the molten steel in the vacuum chamber by a top-blown gas plasma spray gun2Plasma, adjusting plasma arc to aim at RH downcomer, performing heat compensation on molten steel, increasing the flow of lift gas, adjusting potential and gun position to determine the flame distance of plasma, and utilizing CO2The plasma arc blows molten steel for 3-8 min, and the molten steel is subjected to deep degassing;
in the high-efficiency inclusion removing period, the control system adds alloy to the RH vacuum chamber based on the data information when the previous stage is finished, and top-blown CO is2Rapidly switching to top-blown Ar plasma and reducing flow, aligning a plasma spray gun to an RH downcomer, simultaneously adjusting the potential and the gun position to determine the plasma flame distance, and further carrying out Ar plasmaAnd (5) carrying out body spraying for 5-10 min, and finally finishing the refining task.
The technical effects are as follows: the invention combines gas plasma technology, RH refining and CO2The excellent characteristics of the method solve the technical problems of limited molten steel cleanliness, slow production rhythm and the like in the existing RH refining process.
The technical scheme of the invention is further defined as follows:
in the RH refining method for deeply purifying the molten steel, the RH ladle enters the station, the components and the temperature of the molten steel are measured, and the conditions of the molten steel are uploaded to a control system.
In the method for deeply purifying the molten steel by RH refining, the control system regulates and controls top-blown CO on line by using the top-blown gas control valve group based on the acquired molten steel data information in the deep degassing period of the molten steel2The input flow rate is 0.4-0.8 Nm3H.t, adjusting the gun position to a proper position, aligning the gun head to the RH downcomer, adjusting the flame distance of the plasma through the electric potential, and spraying CO to the molten steel surface2The plasma improves the air flow by 5-10%, and the time is controlled to be 3-8 min.
According to the method for deeply purifying the molten steel by RH refining, in the deep degassing process of the molten steel, the monitoring system monitors the component information and the temperature of the molten steel in real time, and if the H, N content of the molten steel meets the steel grade requirement, the control system carries out alloy addition to the RH vacuum chamber through the feeding system.
In the method for deeply purifying molten steel by RH refining, during the high-efficiency inclusion removing period, the top-blown gas is instantly switched to Ar through the top-blown gas control valve group, and the input flow is 0.2-0.5 Nm3And h.t, adjusting the position of the gun to a proper position, aligning the gun head to the RH downcomer, adjusting the flame distance of the plasma through the electric potential, spraying Ar plasma to the molten steel, and controlling the time to be 5-10 min, wherein the flow of the lifting gas is reduced by 15-25% on the basis of the step S2.
The method for deeply purifying the molten steel by RH refining has the advantages that the inclusion removing process is efficient, the monitoring system analyzes the components and the temperature of the molten steel, the control system cuts off the Ar supply of the top-blowing plasma gun on line after the components and the temperature reach the standard, the gun body is controlled to reset, and then RH is broken.
In the method for deeply purifying molten steel by RH refining, the plasma spray gun is aligned to the RH downcomer, and the angle is controlled to be 10-20 degrees.
In the method for deeply purifying the molten steel by RH refining, the plasma torch adopts low-temperature plasma, and the temperature of the plasma is controlled to be 3000-4000K by potential adjustment.
The method for deeply purifying the molten steel by RH refining is suitable for the refining process of the molten steel with carbon content more than or equal to 0.6 percent.
The invention has the beneficial effects that:
(1) in the deep degassing period of the molten steel, tiny and dispersed bubbles in the molten steel are greatly increased on the basis of a small amount of decarburization; in the efficient inclusion removing period, Ar plasma is used for controlling the temperature of the molten steel, so that the refining slag has better fluidity, impurities are fully floated for time and are captured by the slag, the Ar plasma is used for stirring the molten steel, the impurities are quickly floated, the molten steel is purified, and the refining time is shortened;
(2) the invention can strengthen the stirring effect in the RH refining process, further reduce the content of harmful elements such as H, N and the like in the molten steel, greatly reduce inclusions in the steel, improve the cleanliness of the molten steel, simultaneously improve the yield of alloy, avoid the great temperature drop of the molten steel, shorten the refining rhythm and ensure that the average end point hydrogen content of the molten steel is less than 1.2 multiplied by 10-6The nitrogen removal amount is increased by 5 to 15 x 10-6The RH refining period is shortened by 2-5 min, and the quality of the molten steel is improved;
(3) the method is suitable for the refining process of the RH ladle at 30-300 t, and breaks the limit of cleanliness of the traditional process.
Detailed Description
The method for deeply purifying molten steel by RH refining provided by the embodiment is applied to a 150t RH refining process, lifting gas is Ar, a plasma torch adopts low-temperature plasma, the temperature of the plasma is controlled to be 3500K through potential adjustment, and the ultimate vacuum degree is 100Pa, and the method specifically comprises the following steps:
s1, RH ladle is put into the station, the components and the temperature of the molten steel are measured, the conditions of the molten steel are uploaded to a control system, and simultaneously, 130Nm lifting gas is started3H (normal usage flow 120Nm3A 8% increase of 130 Nm/h3H), vacuumizing to 100 Pa;
s2, in the deep degassing period of the molten steel, the control system regulates and controls top-blown CO on line by using a top-blown gas control valve group based on the molten steel data information acquired in the step S12The input flow rate is 0.6Nm3H.t, adjusting the gun position to a proper position, deflecting the gun body angle by 15 degrees to point to the center of the downcomer, adjusting the flame distance of the plasma through the electric potential, and spraying CO to the molten steel surface2Plasma, increasing the gas flow to 130Nm3H, controlling the time to be 5 min;
s3, monitoring the molten steel component information and temperature in real time by a monitoring system, wherein the content of H, N is respectively reduced to 1.4ppm and 24ppm, the temperature is reduced by 8 ℃, and a control system adds 100kg of aluminum blocks to the molten steel in the RH vacuum chamber by using a feeding system;
s4, in the high-efficiency inclusion removing period, the top-blown gas is instantly switched to Ar through the top-blown gas control valve group, and the input flow is 0.3Nm3H.t, adjusting the gun position to a proper position, deflecting the gun body by an angle of 15 degrees to point to the center of the downcomer, adjusting the flame distance of the plasma through the electric potential, spraying Ar plasma to the molten steel, and increasing the gas flow by 100Nm3H, controlling the time to be 7 min;
and S5, analyzing the components and the temperature of the molten steel by the monitoring system, cutting off the supply of the top-blown plasma gun Ar on line by the control system after the molten steel reaches the standard, controlling the gun body to reset, and then RH breaking.
Compared with the traditional process, the method has the advantages that the content of the refining end point H, N is respectively 0.9ppm and 17ppm, the inclusion content in unit area is obviously reduced, the quality of molten steel is improved, the refining period is shortened by 3min, and the average temperature drop is lower than 20 ℃.
In addition to the above embodiments, the present invention may have other embodiments. All technical solutions formed by adopting equivalent substitutions or equivalent transformations fall within the protection scope of the claims of the present invention.
Claims (9)
1. A method for deeply purifying molten steel by RH refining is characterized in that: the RH vacuum refining process comprises 2 stages of a molten steel deep degassing period and a high-efficiency inclusion removing period,
in the deep degassing period of the molten steel, the control system sets top-blown CO based on the components of RH station-entering molten steel2Flow rate, spraying CO to the molten steel in the vacuum chamber by a top-blown gas plasma spray gun2Plasma, adjusting plasma arc to aim at RH downcomer, performing heat compensation on molten steel, increasing the flow of lift gas, adjusting potential and gun position to determine the flame distance of plasma, and utilizing CO2The plasma arc blows molten steel for 3-8 min, and the molten steel is subjected to deep degassing;
in the high-efficiency inclusion removing period, the control system adds alloy to the RH vacuum chamber based on the data information when the previous stage is finished, and top-blown CO is2And rapidly switching to top-blown Ar plasma, reducing the flow, aligning a plasma spray gun to the RH downcomer, adjusting the potential and the gun position to determine the flame distance of the plasma, further spraying the Ar plasma for 5-10 min, and finally finishing the refining task.
2. The method of claim 1 for RH refining of deep purification of molten steel, wherein: and (4) the RH ladle enters the station, the components and the temperature of the molten steel are measured, and the conditions of the molten steel are uploaded to a control system.
3. The method of claim 1 for RH refining of deep purification of molten steel, wherein: in the deep degassing period of the molten steel, the control system regulates and controls top-blown CO on line by utilizing a top-blown gas control valve group based on the acquired molten steel data information2The input flow rate is 0.4-0.8 Nm3H.t, adjusting the gun position to a proper position, aligning the gun head to the RH downcomer, adjusting the flame distance of the plasma through the electric potential, and spraying CO to the molten steel surface2The plasma improves the air flow by 5-10%, and the time is controlled to be 3-8 min.
4. The method of claim 1 for RH refining of deep purification of molten steel, wherein: and in the deep degassing process of the molten steel, monitoring the component information and the temperature of the molten steel by a monitoring system in real time, and if the H, N content of the molten steel meets the steel grade requirement, adding alloy into the RH vacuum chamber by a control system.
5. The method of claim 3, wherein the RH refining further purifies the molten steel, and the method further comprises the steps of: in the efficient inclusion removing period, the top-blown gas is instantly switched to Ar through the top-blown gas control valve group, and the input flow is 0.2-0.5 Nm3And h.t, adjusting the position of the gun to a proper position, aligning the gun head to the RH downcomer, adjusting the flame distance of the plasma through the electric potential, spraying Ar plasma to the molten steel, and controlling the time to be 5-10 min, wherein the flow of the lifting gas is reduced by 15-25% on the basis of the step S2.
6. The method of claim 1 for RH refining of deep purification of molten steel, wherein: the inclusion removing process is efficient, the monitoring system analyzes the components and the temperature of the molten steel, after the molten steel reaches the standard, the control system cuts off the Ar supply of the top-blown plasma gun on line, controls the gun body to reset, and then RH breaks the air.
7. The method of claim 1 for RH refining of deep purification of molten steel, wherein: the plasma torch is aligned to the RH downcomer, and the angle is controlled to be 10-20 degrees.
8. The method of claim 1 for RH refining of deep purification of molten steel, wherein: the plasma spray gun adopts low-temperature plasma, and the temperature of the plasma is controlled to be 3000-4000K through potential adjustment.
9. The method of claim 1 for RH refining of deep purification of molten steel, wherein: is suitable for the refining process of the molten steel with carbon content more than or equal to 0.6 percent.
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| CN202010867635.7A CN112226582A (en) | 2020-08-26 | 2020-08-26 | Method for deeply purifying molten steel by RH refining |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115287406A (en) * | 2022-07-18 | 2022-11-04 | 首钢集团有限公司 | Smelting method for removing impurities in steel |
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| JPH05195043A (en) * | 1992-01-24 | 1993-08-03 | Kawasaki Steel Corp | Method for injecting flux for refining molten metal and device therefor |
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| CN1164873A (en) * | 1995-08-28 | 1997-11-12 | 新日本制铁株式会社 | Process for vacuum refining of molten steel and apparatus therefor |
| CN109957637A (en) * | 2019-03-27 | 2019-07-02 | 北京科技大学 | A kind of RH blowing CO2Refine the dynamic control method of ultra-low-carbon steel |
| CN110982992A (en) * | 2019-12-16 | 2020-04-10 | 首钢集团有限公司 | RH vacuum decarburization method |
| CN111394543A (en) * | 2020-04-15 | 2020-07-10 | 北京科技大学 | RH (relative humidity) efficient deep decarburization control method based on plasma jet |
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2020
- 2020-08-26 CN CN202010867635.7A patent/CN112226582A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH05195043A (en) * | 1992-01-24 | 1993-08-03 | Kawasaki Steel Corp | Method for injecting flux for refining molten metal and device therefor |
| CN1126497A (en) * | 1993-06-04 | 1996-07-10 | 新日本制铁株式会社 | Method of manufacturing low carbon molten steel by vacuum degasification and decarbonization |
| CN1164873A (en) * | 1995-08-28 | 1997-11-12 | 新日本制铁株式会社 | Process for vacuum refining of molten steel and apparatus therefor |
| CN109957637A (en) * | 2019-03-27 | 2019-07-02 | 北京科技大学 | A kind of RH blowing CO2Refine the dynamic control method of ultra-low-carbon steel |
| CN110982992A (en) * | 2019-12-16 | 2020-04-10 | 首钢集团有限公司 | RH vacuum decarburization method |
| CN111394543A (en) * | 2020-04-15 | 2020-07-10 | 北京科技大学 | RH (relative humidity) efficient deep decarburization control method based on plasma jet |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115287406A (en) * | 2022-07-18 | 2022-11-04 | 首钢集团有限公司 | Smelting method for removing impurities in steel |
| CN115287406B (en) * | 2022-07-18 | 2023-07-11 | 首钢集团有限公司 | Smelting method for removing inclusions in steel |
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