KR100916899B1 - The method for removing sulfur and preventing nitrogen pick-up at the deoxidized steel - Google Patents

The method for removing sulfur and preventing nitrogen pick-up at the deoxidized steel Download PDF

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KR100916899B1
KR100916899B1 KR1020020085327A KR20020085327A KR100916899B1 KR 100916899 B1 KR100916899 B1 KR 100916899B1 KR 1020020085327 A KR1020020085327 A KR 1020020085327A KR 20020085327 A KR20020085327 A KR 20020085327A KR 100916899 B1 KR100916899 B1 KR 100916899B1
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steel
stirring
molten steel
nitrogen
caco
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KR20040058815A (en
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서정도
심상철
김시욱
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주식회사 포스코
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    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21CPROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04Removing impurities by adding a treating agent
    • C21C7/064Dephosphorising; Desulfurising
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21CPROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/0075Treating in a ladle furnace, e.g. up-/reheating of molten steel within the ladle
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21CPROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04Removing impurities by adding a treating agent
    • C21C7/064Dephosphorising; Desulfurising
    • C21C7/0645Agents used for dephosphorising or desulfurising
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27FURNACES; KILNS; OVENS; RETORTS
    • F27DDETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D3/00Charging; Discharging; Manipulation of charge
    • F27D3/0025Charging or loading melting furnaces with material in the solid state
    • F27D3/0026Introducing additives into the melt
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27FURNACES; KILNS; OVENS; RETORTS
    • F27DDETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D27/00Stirring devices for molten material
    • F27D2027/002Gas stirring

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  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Treatment Of Steel In Its Molten State (AREA)

Abstract

본 발명은 강교반 중 발생되는 나탕을 통하여 CaCO3와 Al을 첨가하여 탈황반응을 유도하고 나탕부위를 통하여 질소가 혼입되는 것을 방지하도록 된 탈산용강의 탈황 및 질소 혼입 방지 방법을 제공하는 데 목적이 있다.An object of the present invention is to provide a method for preventing desulfurization and nitrogen incorporation of deoxidation molten steel, which induces desulfurization reaction by adding CaCO 3 and Al through a tang generated during steel stirring and prevents nitrogen from being mixed through the tang part. have.

따라서 본 발명은 탈산용강의 이차정련시 레이들 상부로부터 랜스를 탈산용강에 침지하거나 레이들 바닥의 저취 노즐을 통해 불활성 가스를 취입하여 나탕이 형성되도록 하고, 나탕에 탈산용강 1톤당 CaCO3 2.5㎏ 및 Al 0.4~0.5kg을 동시에 투입하는 투입단계; 투입단계에서 CaCO3 및 Al의 투입된 후 나탕이 유지되도록 탈산용강을 강교반하는 나탕유지단계; 나탕유지단계 후 나탕이 발생되지 않도록 불활성가스의 유량을 줄여 3∼5분 동안 약교반을 실시하는 약교반단계;를 포함하는 탈산용강의 탈황 및 질소혼입 방지방법을 제공한다.Therefore, in the present invention, during secondary refining of the deoxidation steel, the lance is immersed in the deoxidation steel from the upper ladle or inert gas is blown through the lower nozzle of the bottom of the ladle to form a tang, and 2.5 kg of CaCO 3 per ton of the deoxidizing steel in the tang. And input step of simultaneously injecting 0.4 ~ 0.5kg Al; Natang maintenance step of stirring the deoxidation steel to maintain the molten after the addition of CaCO 3 and Al in the input step; Provides a method for preventing desulfurization and nitrogen incorporation of the deoxidation steel, including; a weak stirring step of reducing the flow of inert gas after the maintenance of the hot water to reduce the flow of inert gas for 3 to 5 minutes.

슬래그, 교반, 나탕, 탈황, 질소Slag, Stirring, Natang, Desulfurization, Nitrogen

Description

탈산용강의 탈황 및 질소혼입 방지방법{The method for removing sulfur and preventing nitrogen pick-up at the deoxidized steel}The method for removing sulfur and preventing nitrogen pick-up at the deoxidized steel}

도 1은 본 발명에 따른 탈황반응을 도식적으로 나타낸 도면이다.1 is a diagram schematically showing a desulfurization reaction according to the present invention.

도 2는 본 발명에 따른 톱랜스에 의한 용강의 교반을 도식적으로 나타낸 도면이다.2 is a view schematically showing the stirring of the molten steel by the top lance according to the present invention.

도 3은 본 발명에 따른 용강 중 황의 시간에 따른 거동을 나타내는 그래프이다.3 is a graph showing the behavior of sulfur in molten steel according to the present invention.

도4는 본 발명에 따른 용강 중 질소의 시간에 따른 거동을 나타내는 그래프이다.4 is a graph showing the behavior of nitrogen in molten steel over time according to the present invention.

본 발명은 전로에서 출강된 탈산용강의 탈황 및 질소 혼입 방지 방법에 관한 것으로, 더욱 상세하게는 강교반 중 발생되는 나탕을 통하여 CaCO3와 Al을 첨가하여 탈황반응을 유도하고 나탕부위를 통하여 질소가 혼입되는 것을 방지하도록 된 탈산 용강의 탈황 및 질소 혼입 방지 방법에 관한 것이다. The present invention relates to a method for preventing desulfurization and nitrogen incorporation of deoxidized molten steel from a converter, and more specifically, to induce desulfurization by adding CaCO 3 and Al through a hot spring generated during steel stirring and adding nitrogen to the hot spring site. The present invention relates to a method for preventing desulfurization and nitrogen incorporation of deoxidized molten steel to prevent mixing.

일반적으로 전로에서 취련이 완료된 탈산용강은 수강 레이들에 출강되어 성분조정, 온도균일화, 탈황 및 개재물 제어를 위해 이차정련단계로 이동된다.Generally, deoxidation molten steel, which has been blown in the converter, is moved to the steel ladle and moved to the secondary refining stage for composition adjustment, temperature uniformity, desulfurization, and inclusion control.

이차정련단계에서는 상부랜스 혹은 하부의 저취노즐을 통하여 아르곤 등의 불활성가스를 취입하여 용강을 교반한다.In the secondary refining step, inert gas such as argon is blown through the upper lance or the lower odor nozzle to stir the molten steel.

이 때 탈산 강의 탈황을 위하여 슬래그 중에 CaO를 투입하고 용강중에 Al을 투입하고, 반응계면적을 크게 하고 투입된 CaO가 슬래그중으로 잘 용해되도록 하기 위해 장시간 강교반을 실시하여 용강/슬래그 간 영구반응(Permanent reaction)을 유도한다.At this time, CaO is added to slag for desulfurization of deoxidized steel, Al is added to molten steel, and the reaction reaction is continued for a long time in order to increase the reaction area and dissolve CaO into slag. ).

그러나 이러한 과정에서 용강이 대기와 접촉할 수 있는 시간이 길어지고, 용강표면은 탈산되어 표면 사이트가 비어있는 상태가 되므로 대기 중 질소가 용강 표면에 쉽게 흡착, 용강 중에 혼입되어 제품에 결함이 생기는 문제점이 있다.However, in this process, the time that molten steel can come into contact with the atmosphere is long, and the surface of the molten steel is deoxidized and the surface site becomes empty, so that nitrogen in the atmosphere is easily adsorbed to the molten steel surface and mixed in the molten steel to cause defects in the product. There is this.

본 발명은 상기와 같은 문제점을 해결하기 위하여 안출된 것으로, 강교반 중 발생되는 나탕을 통하여 CaCO3와 Al을 첨가하여 탈황반응을 유도하고 나탕부위를 통하여 질소가 혼입되는 것을 방지하도록 된 탈산용강의 탈황 및 질소 혼입 방지 방법을 제공하는 데 목적이 있다.The present invention has been made to solve the above problems, the addition of CaCO 3 and Al through the hot springs generated during steel stirring to induce desulfurization reaction and to prevent nitrogen from being mixed through the hot spring site It is an object to provide a method for preventing desulfurization and nitrogen incorporation.

상기한 목적을 달성하기 위하여 본 발명은 탈산용강의 이차정련시 레이들 상부로부터 랜스를 탈산용강에 침지하거나 레이들 바닥의 저취 노즐을 통해 불활성 가스를 취입하여 나탕이 형성되도록 하고, 나탕에 탈산용강 1톤당 CaCO3 2.5㎏ 및 Al 0.4~0.5kg을 동시에 투입하는 투입단계; 투입단계에서 CaCO3 및 Al의 투입된 후 나탕이 유지되도록 탈산용강을 강교반하는 나탕유지단계; 나탕유지단계 후 나탕이 발생되지 않도록 불활성가스의 유량을 줄여 3∼5분 동안 약교반을 실시하는 약교반단계;를 포함하는 탈산용강의 탈황 및 질소혼입 방지방법을 제공한다.In order to achieve the above object, the present invention is to immerse the lance in the deoxidizing steel from the upper ladle during secondary refining of the deoxidizing steel, or to blow inert gas through the lower nozzle of the ladle bottom to form a molten steel, the deoxidizing steel in the rape An input step of simultaneously injecting 2.5 kg of CaCO 3 and 0.4-0.5 kg of Al per ton; Natang maintenance step of stirring the deoxidation steel to maintain the molten after the addition of CaCO 3 and Al in the input step; Provides a method for preventing desulfurization and nitrogen incorporation of the deoxidation steel, including; a weak stirring step of reducing the flow of inert gas after the maintenance of the hot water to reduce the flow of inert gas for 3 to 5 minutes.

또한 나탕유지단계에서 나탕이 유지되도록 탈산용강을 5분동안 강교반하는 것이 바람직하다.In addition, it is preferable to stir the deoxidation molten steel for 5 minutes so that the lacquer is maintained in the lacquer holding step.

이하, 본 발명에 따른 탈산용강의 탈황 및 질소혼입 방지방법을 첨부도면을 참조하여 설명하면 다음과 같다.Hereinafter, a method for preventing desulfurization and nitrogen mixing of deoxidation molten steel according to the present invention will be described with reference to the accompanying drawings.

도 1은 본 발명에 따른 탈황반응을 도식적으로 나타낸 도면이고, 도 2는 본 발명에 따른 톱랜스에 의한 용강의 교반을 도식적으로 나타낸 도면이며, 도 3은 본 발명에 따른 용강 중 황의 시간에 따른 거동을 나타내는 그래프이고, 도4는 본 발명에 따른 용강 중 질소의 시간에 따른 거동을 나타내는 그래프이다.1 is a diagram schematically showing the desulfurization reaction according to the present invention, Figure 2 is a diagram showing the stirring of the molten steel by the top lance according to the present invention, Figure 3 is the time of sulfur in the molten steel according to the present invention 4 is a graph showing behavior, and FIG. 4 is a graph showing the behavior of nitrogen in molten steel according to the present invention.

먼저 CaCO3 및 Al을 투입하는 투입단계는 불활성가스를 강교반하여 용강의 표면에 슬래그가 덮이지 않는 부위인 나탕이 형성되도록 한다.First, the CaCO 3 and Al input step to stir the inert gas so that the slag which is not covered with slag is formed on the surface of the molten steel.

이 때 나탕이 형성되면 나탕의 상부로부터 용강 1톤당 CaCO3를 2.5kg, Al을 용강 1톤당 0.4~0.5kg을 투입한다.At this time, when the tang is formed, 2.5 kg of CaCO 3 per tonne of molten steel and 0.4 to 0.5 kg per tonne of molten steel are injected from the top of the tang.

여기서 투입된 CaCO3와 Al은 고온에서 다음과 같은 반응을 통해 탈황과 함 께 질소의 혼입이 방지된다.CaCO 3 and Al added here are prevented from mixing nitrogen with desulfurization through the following reaction at high temperature.

CaCO3(s) = CaO(s) + CO2(g)CaCO 3 (s) = CaO (s) + CO 2 (g)

3CO2(g) + 2Al(l) →Al2O3(s) + 3CO(g)3CO 2 (g) + 2Al ( l ) → Al 2 O 3 (s) + 3CO (g)

CaO(s) + Al2O3(s) = CaO-Al2O3(l)CaO (s) + Al 2 O 3 (s) = CaO-Al 2 O 3 ( l )

CaO-Al2O3(l) + S = CaO-Al2O3-S(l) CaO-Al 2 O 3 ( l ) + S = CaO-Al 2 O 3 -S ( l )

(여기서 (s)는 고체, (l)은 액체, (g)는 기체를 나타낸다.)(Where (s) is solid, ( l ) is liquid and (g) is gas.)

상기 반응식 1은 흡열반응이나, 반응식 2가 발열반응이므로 온도에 대한 보상이 일어나 온도변화는 없다. 그리고 반응식 1과 같이 CaCO3에 의해 생성된 CaO는 반응식 2에 의해 생성된 Al2O3와 반응하여 반응식 3과 같이 저융점의 플럭스인 CaO-Al2O3로 변하게 된다.The reaction scheme 1 is an endothermic reaction, but because the reaction scheme 2 is an exothermic reaction, there is no temperature change due to compensation for temperature. As shown in Scheme 1, CaO produced by CaCO 3 reacts with Al 2 O 3 produced by Scheme 2 to change to CaO-Al 2 O 3 , which is a low melting flux as shown in Scheme 3.

이러한 저융점의 플럭스는 용강의 유동에 의해 슬래그/용강 계면으로 이동해 온 황(S)과 반응식 4와 같이 CaO-Al2O3-S가 되어 부상 제거된다.These low melting fluxes are removed by sulfur (S) which has moved to the slag / molten steel interface by molten steel and CaO-Al 2 O 3 -S as in Scheme 4.

이와 같이 저융점의 플럭스에 의해서 탈활반응을 진행시키면 CaO 고상이 용강 중 황과 반응하는 속도보다 훨씬 빠르게 탈황반응이 진행되기 때문에 탈황을 위 한 강교반 시간을 줄일 수 있어 부가적으로 질소 혼입량을 줄일 수 있다.In this way, if the deactivation reaction is carried out by the low melting point flux, the desulfurization reaction proceeds much faster than the CaO solid phase reacts with sulfur in molten steel, thereby reducing the stirring time for desulfurization and additionally reducing the nitrogen content. Can be.

본 발명에서 CaCO3을 용강 1톤당 2.5kg으로 한 것은 그 이하로 할 경우 탈황율을 30~50% 이상 얻기가 어렵고, 그 이상으로 할 경우에는 CaO의 양이 많아져서 고융점의 슬래그가 조성이 되어 점도가 높아져 슬래그에 의한 정련능력이 전반적으로 떨어지기 때문이다. In the present invention, it is difficult to obtain the desulfurization rate of 30-50% or more when the CaCO 3 is 2.5kg per ton of molten steel, and when it is more than that, the amount of CaO increases and the slag of high melting point This is because the viscosity becomes high and the refining ability by slag generally falls.

또한 Al을 용강 1톤당 0.4kg∼0.5kg으로 한 것은Al은 CaCO3에 의해 생성된 CO2에 의해 산화되어 Al2O3가 생성되는데, 이 생성된 양이 CaCO3에 의해 생성된 CaO와 반응하여 반응식 3과 같은 저융점의 플럭스를 형성할 수 있도록 하기 위함이다.In addition, Al made 0.4 kg to 0.5 kg per ton of molten steel, Al is oxidized by CO 2 produced by CaCO 3 to form Al 2 O 3 , which is reacted with CaO produced by CaCO 3 . This is to form a low melting flux as shown in Scheme 3.

다음으로 유지단계는 투입단계에서 CaCO3 및 Al의 투입 후 나탕이 5분동안 유지되도록 탈산용강을 강교반한다.Next, in the holding step, the deoxidation steel is stir-stirred so that the hot water is maintained for 5 minutes after CaCO 3 and Al are added.

나탕에 투입된 CaCO3 및 Al은 탈산용강의 탈황이 충분히 일어날 수 있도록 하기 위하여 5분동안 나탕을 유지하여야 한다. 그러나 나탕을 5분이상 유지시키면 CaCO3 및 Al의 반응에 의해 용강의 표면에서 CO가스의 발생이 떨어지므로 CO가스의 블로킹능력이 떨어져 질소가 용강내로 혼입된다.CaCO 3 and Al added to the ground must hold the ground for 5 minutes to allow sufficient desulfurization of the deoxidation steel. However, if the tang is maintained for more than 5 minutes, the generation of CO gas is reduced on the surface of the molten steel by the reaction of CaCO 3 and Al, so the blocking ability of the CO gas is reduced, and nitrogen is mixed into the molten steel.

이러한 탈산용으로의 질소 혼입은 용강 표면에 활성제인 산소가 없어 용강 표면이 자유표면(Free surface)이 되어 빈 사이트에 질소가 쉽게 흡착되어 탈산용강으로 용해되어 들어오는 반응 기구를 따르게 된다. 또한 슬래그가 용강을 덮고 있으면 대기와의 접촉이 없어 질소 혼입이 잘 일어나지 않지만, 강교반에 의해 나 탕이 형성된 경우에는 질소 혼입은 불가피하게 발생되는 것이다. Nitrogen incorporation for deoxidation is followed by a reaction mechanism in which there is no oxygen as an activator on the molten steel surface so that the molten steel surface becomes a free surface, and nitrogen is easily adsorbed to the empty site and dissolved into the deoxidizing steel. In addition, if the slag covers molten steel, there is no contact with the atmosphere, and nitrogen mixing does not occur well. However, when mixing is formed by steel stirring, nitrogen mixing is inevitably generated.

이와같은 질소의 혼입을 방지하기 위해 본 발명에서는 CaCO3에 의해 형성된 CO2가 반응식 2와 같이 Al와 반응하여 최종적으로 슬래그/용강 계면에서 CO 가스가 활발하게 발생하도록 하여 용강 표면 사이트를 CO로 보호(blocking)함으로써 질소의 흡착을 방지할 수 있게 되어, 탈산 용강의 탈황을 위한 강교반 중에 대기로부터의 질소 혼입을 막을 수 있다.In order to prevent such nitrogen incorporation, in the present invention, the CO 2 formed by CaCO 3 reacts with Al as in Scheme 2 to finally generate active CO gas at the slag / molten steel interface, thereby protecting the molten steel surface site with CO. By blocking, it is possible to prevent the adsorption of nitrogen, thereby preventing the incorporation of nitrogen from the atmosphere during steel stirring for desulfurization of the deoxidized molten steel.

다음으로 약교반단계는 유지단계 후 불활성 가스의 양을 줄여 나탕이 형성되지 않도록한 상태에서 3분~5분 동안 약교반을 실시하는 단계이다.Next, the stirring step is a step of performing the stirring for 3 to 5 minutes in a state in which the amount of inert gas is reduced to prevent the formation of ground sugar after the maintenance step.

약교반단계에서는 반응식 3에 의해 생성된 저융점의 플럭스가 반응에 기여하지 않고 용강중에 잔존해 있거나, 반응식 4와 같이 용강 중 황과 반응을 하였으나 그 생성물이 강교반에 의해 슬래그중으로 충분히 흡수되지 못한 경우 잔류생성물들을 슬래그 중으로 제거하게 된다.In the low stirring step, the low melting flux generated by Equation 3 remained in molten steel without contributing to the reaction, or reacted with sulfur in molten steel as in Equation 4, but the product was not sufficiently absorbed into slag by steel stirring. The residual product is then removed into the slag.

여기서 약교반은 용강의 나탕이 형성되지 않고, 슬래그가 용강 표면을 덮고 있는 상태를 유지하면서 행하는 교반을 의미한다.Here, stirring means that stirring is performed while slag does not form molten steel and slag covers the molten steel surface.

그러나 이와 같은 약교반시간이 길어지면 잔류생성물들을 충분히 제거할 수 있으나 너무 길면 용강온도가 하락하기 때문에 3분~5분동안 용강을 약교반하는 것이 바람직하다.However, if the stirring time is long, the residual products can be sufficiently removed, but if it is too long, it is preferable to stir the molten steel for 3 to 5 minutes because the temperature of the molten steel decreases.

(실시예)(Example)

본 실시예에서는 200kg급 대기유도로를 이용하여 모사 실험을 실시하였다. In this example, a simulated experiment was conducted using a 200kg air induction road.                     

여기서 용강은 중량%로, 탄소(C): 0.1%, 실리콘(Si): 0.3%, 망간(Mn):1.1%, 알루미늄(Al):0.035%, 황(S):0.012%로 조성되며 총 중량은 130kg이다. The molten steel is composed of weight%, carbon (C): 0.1%, silicon (Si): 0.3%, manganese (Mn): 1.1%, aluminum (Al): 0.035%, and sulfur (S): 0.012%. The weight is 130 kg.

또한 슬래그는 중량%로, CaO:55.2%, SiO2:9.1%, Al2O3:30.6%, MgO:5.1 %를 초기 조성으로 하여 총중량은 2.5 kg이다.In addition, the slag is by weight, CaO: 55.2%, SiO 2 : 9.1%, Al 2 O 3 : 30.6%, MgO: 5.1% as an initial composition, the total weight is 2.5 kg.

먼저 용강의 온도는 1600℃에서 유지하면서 도 2와 같이 탑랜스를 통해 아르곤(Ar)을 불어주어 용강 나탕을 형성하였으며, 용강 나탕 상부로부터 CaCO3를 0.325kg투입하고, 동시에 Al을 0.065 kg을 투입하였다.First, while maintaining the temperature of the molten steel at 1600 ° C, argon (Ar) was blown through the top lance to form molten steel, as shown in FIG. 2, 0.325kg of CaCO 3 was injected from the molten steel, and 0.065 kg of Al was simultaneously added. It was.

CaCO3와 Al을 투입한 후 5분동안 강교반하여 나탕이 형성되도록 한 후, 아르곤의 양을 줄여 나탕이 형성되지 않도록 약교반을 3분 동안 실시하였다. After adding CaCO 3 and Al, stirring was carried out for 5 minutes to form a tang, and then stirring was performed for 3 minutes to reduce the amount of argon to form a tang.

본 실시예에 따른 실험 중 용강을 수시로 채취하여 용강 중 황과 질소의 거동을 살펴서 탈황능력과 질소의 혼입정도를 분석한다.The molten steel is frequently collected during the experiment according to the present embodiment to examine the behavior of sulfur and nitrogen in the molten steel to analyze the desulfurization ability and the degree of nitrogen incorporation.

먼저 질소거동 비교를 위해 용강 조성과 슬래그 조성을 상기와 같은 방법으로 용해한 후, CaCO3 및 Al을 투입하지 않고 용강 나탕을 형성시켜 5분 이상 대기와 접촉하도록 하였다.First, molten steel composition and slag composition were dissolved in the same manner as described above for comparison of nitrogen behavior, and then molten steel was formed without CaCO 3 and Al to be in contact with the air for at least 5 minutes.

도 3은 본 발명에 따른 용강 중 황의 시간에 따른 거동을 나타내는 그래프로서 초기의 황 조성은 0.012중량%이지만 최종적으로 0.0062중량% 까지 감소한 것을 알 수 있다. 이러한 탈황율은 거의 50%에 이를 정도로 매우 우수하다.Figure 3 is a graph showing the behavior of sulfur in the molten steel over time according to the present invention can be seen that the initial sulfur composition is 0.012% by weight, but finally reduced to 0.0062% by weight. This desulfurization rate is very good, reaching almost 50%.

도4는 시간에 따른 질소의 거동을 나타내는 그래프로서 CaCO3 및 Al을 투입 하지 않은 경우에는 탑랜스에 의한 강교반 후 지속적으로 질소가 상승하고 있음을 알 수 있으나, 본 발명의 경우와 같이 CaCO3 및 Al을 투입한 경우에는 탑랜스에 의한 강교반 초기에 질소가 약 1~2 ppm 증가하였다가 그 이후에는 탈황반응을 위해 강교반을 실시함에도 불구하고 CO가스의 발생 반응이 활발히 진행됨으로 질소의 증가가 더 이상 일어나지 않고 농도가 일정하게 유지됨을 알 수 있다.Figure 4 is a graph showing the behavior of nitrogen over time, when CaCO 3 and Al is not added it can be seen that the nitrogen is continuously rising after the steel stirring by the top lance, as in the case of the present invention CaCO3 and When Al was added, nitrogen increased by about 1 ~ 2 ppm at the beginning of steel stirring by the top lance. After that, although the steel was stirred for the desulfurization reaction, the reaction of generating CO gas proceeded actively, increasing the nitrogen. It can be seen that no longer occurs and the concentration remains constant.

즉 CO가스의 발생량이 줄어든 이후에도 이미 탈황 반응이 끝나, 아르곤 교반량을 줄일 수 있으므로 나탕이 형성되지 않아 슬래그에 의해 용강 표면이 덮여 있으므로 질소의 혼입이 일어나지 않음을 알 수 있다.In other words, since the desulfurization reaction is already finished even after the generation amount of CO gas is reduced, since the amount of argon agitation can be reduced, it is understood that no mixing of nitrogen occurs because molten steel is not formed and the molten steel surface is covered by slag.

상기와 같은 본 발명에 따른 탈산용강의 탈황 및 질소혼입 방지방법은 이차정련 설비에서 탈산 용강 중 황을 효과적으로 제거할 수 있고, 동시에 황 제거를 위해 강교반을 실시할 경우에도 대기 중 질소가 용강 나탕 표면을 통해 불가피하게 혼입되는 반응 기구가 억제되므로 제품의 품질이 향상된다.Desulfurization and nitrogen mixing prevention method of the deoxidation molten steel according to the present invention as described above can effectively remove the sulfur in the deoxidation molten steel in the secondary refining equipment, and at the same time, even if the steel stirring to remove the sulfur in the molten steel Natang Reaction mechanisms that are inevitably incorporated through the surface are suppressed, thereby improving product quality.

Claims (2)

탈산용강의 이차정련 시 레이들 상부로부터 랜스를 탈산용강에 침지하거나 레이들 바닥의 저취 노즐을 통해 불활성 가스를 취입하여 나탕이 형성되도록 하고, 상기 나탕에 탈산용강 1톤당 CaCO3 2.5㎏ 및 Al 0.4~0.5kg을 동시에 투입하는 투입단계;During secondary refining of deoxidizing steel, lances are immersed in the deoxidizing steel from the upper part of the ladle or blown with inert gas through a low-pressure nozzle at the bottom of the ladle to form a ground sugar, and 2.5 kg of CaCO 3 per tonne of deoxidizing steel and 0.4 in Al Dosing step of putting ~ 0.5kg at the same time; 상기 투입단계에서 CaCO3 및 Al의 투입된 후 나탕이 유지되도록 탈산용강을 5분 동안 강교반하여 나탕 부위를 통해 질소가 혼입되는 것을 방지하는 나탕유지단계;Natang maintaining step of stirring the deoxidation steel for 5 minutes to maintain the natang after the addition of CaCO 3 and Al in the infusion step to prevent nitrogen from being mixed through the natang area; 상기 나탕유지단계 후 나탕이 발생되지 않도록 불활성가스의 유량을 줄여 3∼5분 동안 약교반을 실시하는 약교반단계;를 포함하는 것을 특징으로 하는 탈산용강의 탈황 및 질소혼입 방지방법.Desulfurization and nitrogen incorporation preventing method of the deoxidation molten steel, characterized in that it comprises a ;; a weak stirring step of performing a stirring for 3 to 5 minutes by reducing the flow rate of the inert gas so that the natang is not generated after the maintenance. 삭제delete
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5754216A (en) 1980-09-16 1982-03-31 Nippon Kokan Kk <Nkk> Production of low solved aluminum steel
JPS6126713A (en) 1984-07-17 1986-02-06 Nippon Steel Corp Method for denitrifying molten iron or molten steel
KR20000041028A (en) * 1998-12-21 2000-07-15 이구택 Method of deoxidizing and bubbling slag
KR20030049285A (en) * 2001-12-14 2003-06-25 주식회사 포스코 Method for Desulphurization-Refining Molten Pig Iron

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5754216A (en) 1980-09-16 1982-03-31 Nippon Kokan Kk <Nkk> Production of low solved aluminum steel
JPS6126713A (en) 1984-07-17 1986-02-06 Nippon Steel Corp Method for denitrifying molten iron or molten steel
KR20000041028A (en) * 1998-12-21 2000-07-15 이구택 Method of deoxidizing and bubbling slag
KR20030049285A (en) * 2001-12-14 2003-06-25 주식회사 포스코 Method for Desulphurization-Refining Molten Pig Iron

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