JPH0472009A - Method for refining high cleanliness steel - Google Patents
Method for refining high cleanliness steelInfo
- Publication number
- JPH0472009A JPH0472009A JP2181760A JP18176090A JPH0472009A JP H0472009 A JPH0472009 A JP H0472009A JP 2181760 A JP2181760 A JP 2181760A JP 18176090 A JP18176090 A JP 18176090A JP H0472009 A JPH0472009 A JP H0472009A
- Authority
- JP
- Japan
- Prior art keywords
- slag
- ladle
- steel
- molten steel
- converter
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 50
- 239000010959 steel Substances 0.000 title claims abstract description 50
- 238000007670 refining Methods 0.000 title claims abstract description 20
- 238000000034 method Methods 0.000 title claims description 18
- 230000003749 cleanliness Effects 0.000 title abstract description 5
- 239000002893 slag Substances 0.000 claims abstract description 86
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims abstract description 44
- 239000000292 calcium oxide Substances 0.000 claims abstract description 22
- 235000012255 calcium oxide Nutrition 0.000 claims abstract description 22
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 12
- 238000010079 rubber tapping Methods 0.000 claims abstract description 9
- 238000002407 reforming Methods 0.000 claims abstract description 7
- 238000007667 floating Methods 0.000 claims abstract description 6
- 238000009849 vacuum degassing Methods 0.000 claims abstract 2
- 238000002844 melting Methods 0.000 claims description 7
- 230000008018 melting Effects 0.000 claims description 7
- 239000000843 powder Substances 0.000 claims description 7
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 239000002184 metal Substances 0.000 claims description 5
- 229910052751 metal Inorganic materials 0.000 claims description 5
- 238000010309 melting process Methods 0.000 claims description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 abstract description 21
- 229910052760 oxygen Inorganic materials 0.000 abstract description 10
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 abstract description 9
- 239000001301 oxygen Substances 0.000 abstract description 9
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 abstract description 7
- 229910052593 corundum Inorganic materials 0.000 abstract description 7
- 229910001845 yogo sapphire Inorganic materials 0.000 abstract description 7
- 229910000805 Pig iron Inorganic materials 0.000 abstract 1
- 238000007664 blowing Methods 0.000 abstract 1
- 238000010521 absorption reaction Methods 0.000 description 7
- 238000007796 conventional method Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- 239000003607 modifier Substances 0.000 description 3
- 238000009628 steelmaking Methods 0.000 description 3
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- 229910001634 calcium fluoride Inorganic materials 0.000 description 2
- 230000004907 flux Effects 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 229910001327 Rimmed steel Inorganic materials 0.000 description 1
- 238000010306 acid treatment Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 235000010216 calcium carbonate Nutrition 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 238000004581 coalescence Methods 0.000 description 1
- 239000000571 coke Substances 0.000 description 1
- 239000010960 cold rolled steel Substances 0.000 description 1
- 229910021540 colemanite Inorganic materials 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005188 flotation Methods 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000003716 rejuvenation Effects 0.000 description 1
- 238000010405 reoxidation reaction Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000002436 steel type Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000003832 thermite Substances 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Landscapes
- Treatment Of Steel In Its Molten State (AREA)
Abstract
Description
〔産業上の利用分野〕
本発明は高清浄度鋼の溶製方法に係り、特に真空２次精
錬におけるスラグを改質してＡｌ２０．吸収能を向上さ
せ、鋼中の〔○〕濃度およびＡｌ２０．介在物の極めて
少いすぐれた高清浄度鋼を得る溶製方法に関する。
〔従来の技術〕
近年、自動車鋼板を中心とした冷延鋼板に対する需要家
の要求は一段と厳しさを増し、これに伴い極低炭素鋼の
低酸素化、高清浄化が求められている。
製鋼工程において、極低炭素鋼の溶鋼清浄化には真空２
次精錬が重要な役割を果しており、清浄化の徹底をはか
るためには真空２次精錬において溶鋼汚染の原因となる
取鍋スラグを無害化し、Ａｌ２２０３介在物吸収能の高
いスラブとすることが重要である。
一般に極低炭素鋼の溶製工程は、先ず大気圧下で酸素を
吹込んで鉄の酸素損失の少いＣ： ０．０３〜０．０５
％まで粗脱炭する工程と、該粗脱炭した溶鋼を取鍋に受
鋼するに当リスラグ改質剤を添加して溶鋼上に浮遊する
スラグを改質する工程と、この改質した溶鋼を真空脱ガ
ス処理する工程と、より成っており、本発明は第２段階
のスラブ改質技術に関するものである。
上記の如きスラグの改質を図り高清浄度鋼を得ようとす
るために、従来多くの研究が開示されている。
例えば、特開昭５９−７０７１０には次の如き技術が開
示されている。この発明は、「製鋼炉から取鍋へ出鋼し
た溶鋼を真空２次精錬するにさいし、製鋼炉からの出鋼
時に製品としてほぼ必要量の脱酸剤を添加すると共に、
脱酸生成物の合体浮上促進のためのフラックスを添加す
るか、もしくはその後頁に酸化性スラブを改質するため
にスラグ還元剤を併用添加する高清浄度鋼の製造方法。
」である。
しかして、上記脱酸剤としてＡｌ２− Ｓｉを用い、フ
ラックスとしてはＣａＯ−ＣａＦ２系を始めとしてＣａ
Ｏ−コレマナイト系、ＣａＯ−抗火石系、ＣａＯ−８ｉ
ｎ２−Ａｌ２０１等を挙げている。
また特開昭６０−１５２６１０には、取鍋等の容器内に
存在するスラブをプラズマ加熱して還元処理する方法が
開示され、還元剤としては黒鉛、コークスの如き固体還
元剤が使用可能であるとしている。
また特開昭６０−１５２６１１には「溶鋼鍋内の溶鋼上
に浮上しているスラグ中にスラグ還元剤を添加して酸化
性スラグを改質する方法において、上記スラグ還元剤と
共にガス発生物質を併用添加するスラグ改質方法。」が
開示されている。ガス発生物質としてＣａ ＣＯ３を使
用し、溶鋼を撹拌するほか、生成したＣａＯにより溶鋼
汚染物質のＦ ｅ Ｏ、Ｍ ｎ Ｏ等を稀釈できるとし
ている。
しかし、これらの従来方法は、転炉からの出鋼時に生石
灰を最初に添加する方法と同様に、取鍋スラグの融点を
上昇させ流動性を低下させるので、その後に添加する還
元剤の効果のばらつきを大きくし、安定して取鍋スラグ
中のＴ、Ｆｅを低下させることができなかった。
従来、上記の如く真空２次精錬のため、転炉から取鍋へ
の出鋼に際し、取鍋に先ず生石灰を添加し、次にＡＭ、
Ｓｉ等を添加していた。すなわち。
Ａｌ、Ｓｉを添加することにより、取鍋スラグの総鉄含
有量（以下Ｔ、Ｆｅと称す）を低減し、精錬後の鋼中の
総酸素含有量Ｔ（０）を３０ｐｐｍ以下として、製品の
介在物欠陥の皆無を意図したものである。しかしながら
、取鍋スラグのＴ、Ｆｅを低下させるため、Ａｎ等の還
元剤を増加させると、スラグのＡｌ２０．介在物吸収能
が低下する。従ってスラグ中のＴ、Ｆｅの低減と、Ａｌ
２０３吸収能の高いスラグ組成とは両立せず、溶鋼清浄
化を安定して得ることを困難ならしめる一因であった。
〔発明が解決しようとする課題〕
本発明の目的は、上記従来技術の課題を解決し、転炉か
ら出鋼された溶鋼の真空２次精錬において、取鍋スラグ
のＴ、Ｆｅを低減すると共に、スラグのＡｌ２０３介在
物吸収能を向上させた高清浄度鋼の効果的な溶製方法を
提供するにある。
〔課題を解決するための手段〕
本発明の要旨とするところは次の如くである。
すなわち、転炉等の精錬炉で溶製した溶鋼を取鍋に出鋼
する工程と、前記取鍋に受鋼した溶鋼上に浮遊するスラ
グを改質する工程と、前記改質した溶鋼を真空脱ガス処
理する工程とを有して成る高清浄度鋼の溶製方法におい
て、前記転炉等による溶製工程においては予備処理溶銑
を使用して未脱酸のまま出鋼し、前記スラブの改質工程
においてはＡｌ滓を還元剤として使用し、Ａｌ滓添加後
の取鍋内スラグに生石灰粉を添加してスラグ中のＣａｂ
／Ａｌ２０．の比を１．６〜１．８に制御することを特
徴とする高清浄度鋼の溶製方法である。
本発明においては、予め脱りんされた予備処理溶銑を使
用して粗脱炭低炭素鋼を精錬し、未脱酸のままいわゆる
リムド出鋼する。従って、従来の如きスラグ改質のため
の取鍋への生石灰の添加は行わず直ちにＡＭ滓を添加す
る。ＡＭ滓はスラブ中のＴ、Ｆｅの低減を目的として添
加するため、その添加量はスラグ中のＴ、Ｆｅ値によっ
て決定される。しかしながら、取鍋スラグの組成を分析
してその結果によることは時間の制約上できないので、
ＡＭ滓の添加量は転炉の吹止め時の酸素含有量によって
決定される。すなわち、吹止め時の酸素含有量１１００
ｐｐに対してＡＭ滓は０．３ｋｇ／ｌの原単位で添加す
る。ＡＭ滓はスラグ改質剤として経済的に有利な還元剤
で、その主要組成は第１表のとおりである。
第１表
本発明者らは、ＲＨ処理前のスラグ中のＴ、Ｆｅを２％
以下に低減し、かつＡｌ滓による生成Ａｌ、Ｏ，の吸収
能の高いスラブ組成に制御するため、Ａｌ滓添加後生石
灰粉の添加を併用してスラグの改質を行った。添加生石
灰粉は滓化の促進を図るために粒径３廁以下の粉状生石
灰を使用した。
本発明者らは生石灰粉の添加に当り、スラグ中のＣａＯ
／Ａｌ２０３を種々変えてスラグのＡｌ２０３Ｑ収能と
の関係について調査した結果、第１図を得た。すなわち
、ＣａＯ／Ａｌ２０．の比が１．６〜１．８の範囲にお
いて、スラグのＡｌ２０３Ｑ収能が最大になることを児
呂した。その結果、本発明において取鍋内スラグの改質
に当り、Ａｌ滓添加後、生石灰粉を添加してＣａ○／Ａ
ｌ２０３の比を１．６〜１．８に制御する方法をとるこ
ととした。
ここでＡｆ１２０．吸収能とは真空２次精錬後のスラグ
のＡｆ１２０１％から２次精錬前のスラグのＡｌ２０゜
％を引いたものである。Ｃａ○／Ａｎ２０．の比を１．
６〜１．８の範囲に限定したのは、高いＡｌ。
０３吸収能を得るためで、第１図から明らかな如く１．
８を越すとスラブの融点が溶鋼温度を越えるので凝固し
Ａｌ２０．吸収能を低下させ、一方１゜６未満ではスラ
グの粘性が上昇し、Ａｌ２０．吸収能が低下するからで
ある。
〔作 用〕
本発明で使用する溶鋼は、溶銑予備処理を行った溶銑を
精錬するので、転炉の脱りん負荷は軽減されている。そ
のため、出鋼中の復りん量は少ないので、従来の如く出
鋼中に生石灰の添加は必要がない。
従って出鋼中にスラグの流動性が低下することがなく、
出鋼後直ちにＡｌ滓を添加できる。そのため、従来法に
比しＡｌ滓のスラグ中のＴ、Ｆｅ低減効果は大きく、従
来法ではスラグ中のＴ、Ｆｅ＝４．８％程度にてＴ、Ｆ
ｅ５５％の達成率は６０％であったが、本発明ではスラ
グ中のＴ、Ｆｅ：４．０％平均で、Ｔ、Ｆｅ５５％の達
成率は９０％に向上した。またＡｌ滓原単位を低減する
ことができる。
また、Ａｌ滓を取鍋に添加するとテルミット反応により
多量の熱を発生し、そこへ生石灰を添加するので生石灰
は容易に滓化する。一方、スラグ中のＣａ○／Ａｌ２０
３は１．６〜１．８の範囲に調整されているので真空２
次精錬におけるＡｌ説醋酸処理中発生するＡｌ２０．介
在物は効率よくスラグ中に吸引され、かっスラグ中のＴ
、Ｆｅは安定して低減されているので溶鋼再酸化の可能
性も極めて低く、安定して高清浄度鋼を製造することが
できる。
〔実施例〕
第２表に示す如く、同一鋼種の溶鋼を転炉がら取鍋に出
鋼し、本発明法および従来法により改質剤を添加し、そ
の後はそれぞれ同一方法で真空２次精錬を行い、鋳片に
連続鋳造を行った。
同じく第２表に鋳造された鋳片の酸素含有量とＡｌ２０
．系介在物の数を示した。第２表から明らかな如く本発
明実施例は従来例に比して、Ａｌ滓の使用原単位は低く
、鋳片は全酸素含有量およびＡｌ２０３Ｑ在物が少なく
すぐれた清浄度を有している。
第２表
〔発明の効果〕
本発明による高清浄度鋼溶製におけるスラグの改質方法
は、上記実施例からも明らかな如く、転炉から取鍋への
出鋼に際し、まずＡｌ滓を添加し、次にＣａ○／Ａｌ２
０．の比が１．６〜１．８の範囲になる如く生石灰粉を
添加し、真空２次精錬のスラグのＡｌ２０３介在物吸収
能を向上することによって次の効果を挙げることができ
た。
（イ）真空２次精錬終了後の鋼中Ｔ[Industrial Field of Application] The present invention relates to a method for producing high-cleanliness steel, and in particular to a method for producing high-cleanliness steel, particularly by modifying slag in vacuum secondary refining to produce Al20. It improves absorption capacity and reduces [○] concentration in steel and Al20. This invention relates to a melting method for obtaining excellent high-cleanliness steel with extremely few inclusions. [Prior Art] In recent years, customer demands for cold-rolled steel sheets, mainly automotive steel sheets, have become even more severe, and along with this, there has been a demand for ultra-low carbon steels with low oxygen content and high purity. In the steelmaking process, vacuum 2 is used to clean molten steel of ultra-low carbon steel.
Secondary refining plays an important role, and in order to ensure thorough cleaning, it is important to render the ladle slag that causes molten steel contamination harmless in the vacuum secondary refining, and to create a slab with a high ability to absorb Al2203 inclusions. It is. Generally, in the melting process of ultra-low carbon steel, oxygen is first blown into the iron under atmospheric pressure to reduce oxygen loss in the iron: C: 0.03 to 0.05
%, a step of adding this slag modifier to the roughly decarburized molten steel received in a ladle to modify the slag floating on the molten steel, and a step of modifying the slag floating on the molten steel. The present invention relates to the second stage slab reforming technology. Many studies have been disclosed in the past in order to improve the above-mentioned slag and obtain high-cleanliness steel. For example, Japanese Patent Laid-Open No. 59-70710 discloses the following technology. This invention is based on the following technology: ``When performing secondary vacuum refining of molten steel tapped from a steelmaking furnace into a ladle, a deoxidizing agent is added in an amount almost required for the product at the time of tapping from the steelmaking furnace, and
A method for producing high-cleanliness steel, in which a flux is added to promote the coalescence and flotation of deoxidized products, or a slag reducing agent is subsequently added in order to modify the oxidizing slab. ”. Therefore, Al2-Si is used as the deoxidizing agent, and CaO-CaF2 system and other CaO-CaF2 fluxes are used as the deoxidizing agent.
O-Colemanite type, CaO-Anti-flint type, CaO-8i
n2-Al201 etc. are listed. Further, JP-A-60-152610 discloses a method for reducing a slab present in a container such as a ladle by plasma heating, and solid reducing agents such as graphite and coke can be used as the reducing agent. It is said that Furthermore, JP-A No. 60-152611 describes a method for modifying oxidizing slag by adding a slag reducing agent to the slag floating above molten steel in a molten steel ladle, in which a gas generating substance is added together with the slag reducing agent. A method for modifying slag in which slag is added in combination.'' is disclosed. CaCO3 is used as a gas generating substance, and in addition to stirring molten steel, the generated CaO can dilute molten steel contaminants such as FeO and MnO. However, these conventional methods raise the melting point of the ladle slag and reduce its fluidity, similar to the method of adding quicklime first when steel is tapped from a converter, so the effect of the reducing agent added afterwards is This increased the variation and made it impossible to stably lower T and Fe in the ladle slag. Conventionally, for secondary vacuum refining as described above, when tapping steel from a converter to a ladle, quicklime was first added to the ladle, then AM,
Si, etc. were added. Namely. By adding Al and Si, the total iron content (hereinafter referred to as T and Fe) of the ladle slag is reduced, and the total oxygen content T(0) in the steel after refining is 30 ppm or less. It is intended to have no inclusion defects. However, if the amount of reducing agent such as An is increased to lower T and Fe in the ladle slag, Al20. The ability to absorb inclusions decreases. Therefore, the reduction of T and Fe in the slag and the reduction of Al
This is incompatible with a slag composition having a high 203 absorption capacity, and is one of the reasons why it is difficult to stably clean molten steel. [Problems to be Solved by the Invention] The purpose of the present invention is to solve the above-mentioned problems of the prior art, and to reduce T and Fe in ladle slag in vacuum secondary refining of molten steel tapped from a converter. The object of the present invention is to provide an effective method for producing high-cleanliness steel in which the ability of slag to absorb Al203 inclusions is improved. [Means for Solving the Problems] The gist of the present invention is as follows. In other words, there are two steps: tapping the molten steel produced in a refining furnace such as a converter into a ladle, reforming the slag floating on the molten steel received in the ladle, and converting the reformed molten steel into a vacuum. In a high-cleanliness steel melting method comprising a degassing step, in the melting step using the converter etc., pretreated hot metal is used to tap the steel without being deoxidized, and the slab is In the reforming process, Al slag is used as a reducing agent, and quicklime powder is added to the slag in the ladle after adding the Al slag to reduce the amount of Cab in the slag.
/Al20. This method is characterized by controlling the ratio of 1.6 to 1.8. In the present invention, crude decarburized low carbon steel is refined using pretreated hot metal that has been dephosphorized in advance, and so-called rimmed steel is tapped without being deoxidized. Therefore, instead of adding quicklime to the ladle for slag modification as in the conventional method, AM slag is added immediately. Since AM slag is added for the purpose of reducing T and Fe in the slab, the amount of addition is determined by the T and Fe values in the slag. However, due to time constraints, it is not possible to analyze the composition of ladle slag and rely on the results.
The amount of AM slag added is determined by the oxygen content when the converter is shut off. That is, the oxygen content at the time of blow-off is 1100
AM slag is added at a basic unit of 0.3 kg/l based on pp. AM slag is an economically advantageous reducing agent as a slag modifier, and its main composition is shown in Table 1. Table 1 The inventors have determined that T and Fe in the slag before RH treatment are 2%.
In order to control the slab composition to have a high absorption capacity for Al, O, and the like produced by the Al slag, the slag was modified by adding quicklime powder after adding the Al slag. As the added quicklime powder, powdered quicklime with a particle size of 3 m or less was used to promote slag formation. The present inventors added CaO in the slag when adding quicklime powder.
Figure 1 was obtained as a result of investigating the relationship between the Al203Q performance of the slag and the Al203Q performance of the slag by changing various amounts of /Al203. That is, CaO/Al20. Koro found that the Al203Q yield of the slag is maximized when the ratio is in the range of 1.6 to 1.8. As a result, in the present invention, when modifying the slag in the ladle, after adding Al slag, quicklime powder was added and Ca○/A
We decided to adopt a method of controlling the ratio of l203 to 1.6 to 1.8. Here Af120. Absorption capacity is defined as 120% Af in the slag after vacuum secondary refining minus 20% Al in slag before secondary refining. Ca○/An20. The ratio of 1.
High Al is limited to a range of 6 to 1.8. 03 absorption capacity, and as is clear from Figure 1, 1.
When the temperature exceeds 8, the melting point of the slab exceeds the temperature of molten steel, so it solidifies and becomes Al20. At less than 1°6, the viscosity of the slag increases; This is because absorption capacity decreases. [Function] Since the molten steel used in the present invention is refined from hot metal that has undergone hot metal pretreatment, the dephosphorization load on the converter is reduced. Therefore, since the amount of rejuvenation during tapping is small, there is no need to add quicklime during tapping as in the past. Therefore, the fluidity of slag does not decrease during tapping,
Al slag can be added immediately after tapping. Therefore, compared to the conventional method, the effect of reducing T and Fe in the slag with Al slag is greater, and in the conventional method, T and Fe in the slag are approximately 4.8%.
The achievement rate of 55% e was 60%, but in the present invention, the achievement rate of 55% T and Fe improved to 90% with an average of 4.0% T and Fe in the slag. Furthermore, the unit consumption of Al slag can be reduced. Furthermore, when Al slag is added to the ladle, a large amount of heat is generated by the thermite reaction, and since quicklime is added thereto, the quicklime easily turns into slag. On the other hand, Ca○/Al20 in the slag
3 is adjusted to a range of 1.6 to 1.8, so vacuum 2
Al20 generated during the acetic acid treatment in the next refining. The inclusions are efficiently sucked into the slag, and the T in the slag is
, Fe are stably reduced, so the possibility of reoxidation of molten steel is extremely low, and high-cleanliness steel can be stably produced. [Example] As shown in Table 2, molten steel of the same steel type is tapped into a ladle from a converter, a modifier is added by the method of the present invention and a conventional method, and then vacuum secondary refining is performed by the same method. The slab was then continuously cast. Similarly, Table 2 shows the oxygen content and Al20 of the cast slabs.
．． The number of system inclusions is shown. As is clear from Table 2, compared to the conventional example, the usage rate of Al slag is lower in the example of the present invention, and the slab has excellent cleanliness with less total oxygen content and less Al203Q inclusions. . Table 2 [Effects of the Invention] As is clear from the above examples, in the method of modifying slag in high-clean steel melting according to the present invention, Al slag is first added when steel is tapped from a converter to a ladle. Then, Ca○/Al2
0. By adding quicklime powder so that the ratio of 1.6 to 1.8 was achieved and improving the ability of the slag in the vacuum secondary refining to absorb Al203 inclusions, the following effects could be achieved. (a) Steel medium T after vacuum secondary refining
〔０〕≦３０ρρ履
、Ａｌ２０３介在物のきわめて少い高清浄度鋼を安定し
て製造することができた。
（［１）Ａｌ滓原単位を減少することができた。[0]≦30ρρ, high cleanliness steel with extremely few Al203 inclusions could be stably produced. ([1) The unit consumption of Al slag could be reduced.
第１図は真空２次精錬前の取鍋スラグ中のＣａ○／Ａｌ
２０．比とスラグのＡΩ２０３吸収能との関係を示す線
図である。Figure 1 shows Ca○/Al in ladle slag before secondary vacuum refining.
20. It is a diagram showing the relationship between the ratio and the AΩ203 absorption capacity of the slag.
Claims (1)
工程と、前記取鍋に受鋼した溶鋼上に浮遊するスラグを
改質する工程と、前記改質した溶鋼を真空脱ガス処理す
る工程とを有して成る高清浄度鋼の溶製方法において、
前記転炉等による溶製工程においては予備処理溶銑を使
用して未脱酸のまま出鋼し、前記スラグの改質工程にお
いてはＡｌ滓を還元剤として使用し、Ａｌ滓添加後の取
鍋内スラグに生石灰粉を添加してスラグ中のＣａＯ／Ａ
ｌ＿２Ｏ＿３の比を１．６〜１．８に制御することを特
徴とする高清浄度鋼の溶製方法。(1) A process of tapping the molten steel melted in a refining furnace such as a converter into a ladle, a process of reforming the slag floating on the molten steel received in the ladle, and a process of reforming the reformed molten steel. In a high-cleanliness steel melting method comprising a step of vacuum degassing treatment,
In the melting process using the converter etc., the pretreated hot metal is used to tap the steel without being deoxidized, and in the slag reforming process, Al slag is used as a reducing agent, and the ladle after addition of the Al slag is CaO/A in the slag is reduced by adding quicklime powder to the inner slag.
A method for producing high-cleanliness steel, which comprises controlling the ratio of l_2O_3 to 1.6 to 1.8.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2181760A JPH0472009A (en) | 1990-07-10 | 1990-07-10 | Method for refining high cleanliness steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2181760A JPH0472009A (en) | 1990-07-10 | 1990-07-10 | Method for refining high cleanliness steel |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0472009A true JPH0472009A (en) | 1992-03-06 |
Family
ID=16106412
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2181760A Pending JPH0472009A (en) | 1990-07-10 | 1990-07-10 | Method for refining high cleanliness steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0472009A (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0610025A (en) * | 1992-06-29 | 1994-01-18 | Kawasaki Steel Corp | Method for reforming slag in ladle |
| JPH0881954A (en) * | 1994-09-09 | 1996-03-26 | Kowa Sangyo Kk | Anchor method |
| US5624639A (en) * | 1994-11-17 | 1997-04-29 | Nippondenso Co., Ltd. | Gas detecting device for vehicle |
| CN1067727C (en) * | 1996-05-10 | 2001-06-27 | 金明官 | Aluminum-dregs feeding method for iron-steel metallurgy |
| JP2003041315A (en) * | 2001-07-31 | 2003-02-13 | Nkk Corp | Method for manufacturing high cleanliness steel |
| CN102787214A (en) * | 2012-08-08 | 2012-11-21 | 江苏大学 | Ladle furnace refining fluoride-free pre-melted slags, preparation method and using method |
| CN103146872A (en) * | 2013-03-26 | 2013-06-12 | 莱芜钢铁集团有限公司 | Pre-molten synthetic slag and converter tapping reverse wash-heat method using same |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63262412A (en) * | 1987-04-20 | 1988-10-28 | Nippon Steel Corp | Method for cleaning molten steel |
| JPH0230711A (en) * | 1988-07-18 | 1990-02-01 | Kawasaki Steel Corp | Manufacture of extremely low carbon steel having superior cleanness |
-
1990
- 1990-07-10 JP JP2181760A patent/JPH0472009A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63262412A (en) * | 1987-04-20 | 1988-10-28 | Nippon Steel Corp | Method for cleaning molten steel |
| JPH0230711A (en) * | 1988-07-18 | 1990-02-01 | Kawasaki Steel Corp | Manufacture of extremely low carbon steel having superior cleanness |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0610025A (en) * | 1992-06-29 | 1994-01-18 | Kawasaki Steel Corp | Method for reforming slag in ladle |
| JPH0881954A (en) * | 1994-09-09 | 1996-03-26 | Kowa Sangyo Kk | Anchor method |
| US5624639A (en) * | 1994-11-17 | 1997-04-29 | Nippondenso Co., Ltd. | Gas detecting device for vehicle |
| CN1067727C (en) * | 1996-05-10 | 2001-06-27 | 金明官 | Aluminum-dregs feeding method for iron-steel metallurgy |
| JP2003041315A (en) * | 2001-07-31 | 2003-02-13 | Nkk Corp | Method for manufacturing high cleanliness steel |
| CN102787214A (en) * | 2012-08-08 | 2012-11-21 | 江苏大学 | Ladle furnace refining fluoride-free pre-melted slags, preparation method and using method |
| CN103146872A (en) * | 2013-03-26 | 2013-06-12 | 莱芜钢铁集团有限公司 | Pre-molten synthetic slag and converter tapping reverse wash-heat method using same |
| CN103146872B (en) * | 2013-03-26 | 2015-02-18 | 莱芜钢铁集团有限公司 | Pre-molten synthetic slag and converter tapping reverse wash-heat method using same |
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