JP3140256B2 - Slag reforming method - Google Patents
Slag reforming methodInfo
- Publication number
- JP3140256B2 JP3140256B2 JP05125615A JP12561593A JP3140256B2 JP 3140256 B2 JP3140256 B2 JP 3140256B2 JP 05125615 A JP05125615 A JP 05125615A JP 12561593 A JP12561593 A JP 12561593A JP 3140256 B2 JP3140256 B2 JP 3140256B2
- Authority
- JP
- Japan
- Prior art keywords
- slag
- ladle
- molten steel
- reducing agent
- tapping
- 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.)
- Expired - Fee Related
Links
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)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、高清浄度鋼を得るため
のスラグの改質方法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slag reforming method for obtaining high cleanliness steel.
【０００２】[0002]
【従来の技術】一般に高清浄度鋼は、溶鋼をRH真空脱ガ
ス装置等を用いて２次精錬を行うことにより製造されて
いる。溶鋼を清浄化するため２次精錬を行う目的は、RH
真空脱ガス処理時の真空下におけるカーボンによる溶鋼
の脱酸を利用してAl等の脱酸剤を添加する時点での溶鋼
中の〔Ｏ〕を低下することにより Al2O3等の介在物の生
成量を少なくし、またRH真空脱ガス処理の攪拌エネルギ
により溶鋼中に存在する非金属介在物の浮上を促進する
ことにある。2. Description of the Related Art Generally, high cleanliness steel is produced by subjecting molten steel to secondary refining using a RH vacuum degassing apparatus or the like. The purpose of secondary refining to clean molten steel is RH
Inclusions such as Al 2 O 3 by reducing the [O] in the molten steel at the time of adding a deoxidizing agent such as Al by utilizing the deoxidation of molten steel by carbon under vacuum during vacuum degassing And to promote the floating of nonmetallic inclusions present in the molten steel by the stirring energy of the RH vacuum degassing process.
【０００３】このため、溶鋼の２次精錬による効果を発
揮するためには、転炉出鋼時には２次精錬での脱〔Ｃ〕
量分だけ転炉吹止め〔Ｃ〕を高くし、転炉吹止め時点で
の溶鋼中〔Ｏ〕を低く抑え、転炉出鋼時には脱酸剤を投
入しないで未脱酸で出鋼するか、脱酸力の弱い脱酸剤を
少量投入するのが一般的であった。ところで、高清浄度
鋼を製造する場合、〔Ｃ〕が0.05重量％（以下％は重量
％を示す）以上の比較的目標〔Ｃ〕の高い鋼種ではほぼ
満足すべき清浄度が得られていたが、低炭材の場合、転
炉において〔Ｃ〕の吹き下げを行うため、そのスラグは
FeO、MnO 濃度の高い極めて酸化性の高い組成となる。[0003] Therefore, in order to exhibit the effect of the secondary refining of molten steel, it is necessary to remove [C] by secondary refining at the time of tapping the converter.
Make the converter blow stopper [C] high by the amount, keep the molten steel [O] low at the time of the converter blow stop, and do not deoxidize the steel without turning on the deoxidizer when starting the converter. It is common to add a small amount of a deoxidizing agent having a weak deoxidizing power. By the way, in the case of producing a high cleanliness steel, almost satisfactory cleanliness has been obtained with a steel type having a relatively high target [C] of not less than 0.05% by weight (hereinafter,% indicates weight%). However, in the case of low-carbon materials, the slag is
An extremely oxidizing composition with high FeO and MnO concentrations.
【０００４】転炉から取鍋に出鋼された溶鋼上に浮上す
る取鍋スラグ中に残存した FeO、MnO などは２次精錬以
降の工程で溶鋼中の〔Al〕、〔Si〕のような酸素親和力
の強い元素を酸化して非金属介在物を生成する。このた
め溶鋼の清浄度を向上させるため、転炉から出鋼した取
鍋内の溶鋼上に浮上している取鍋スラグを改質すること
が行われている。[0004] FeO, MnO, and the like remaining in the ladle slag floating on the molten steel discharged from the converter into the ladle are removed from the molten steel such as [Al] and [Si] in the molten steel in the processes after the secondary refining. Oxidizes elements with strong oxygen affinity to produce non-metallic inclusions. For this reason, in order to improve the cleanliness of the molten steel, the ladle slag floating on the molten steel in the ladle taken out of the converter is modified.
【０００５】従来、溶鋼清浄度向上（低酸素化）を目的
としたスラグ改質方法として特公平２−19168 号公報の
ように、スラグ還元剤と共にガス発生物質を併用添加す
る方法（Ａ法）が知られており、また低硫鋼溶製を目的
としたスラグ改質方法では、転炉出鋼後に造滓剤を添加
し、取鍋精法（ＬＦ法）などによりスラグを強攪拌かつ
強加熱しながらAl等の還元剤を添加する方法（Ｂ法）な
どが知られている。Conventionally, as a slag reforming method for improving the cleanliness of molten steel (lower oxygen), a method of adding a gas generating substance together with a slag reducing agent as in Japanese Patent Publication No. 2-19168 (Method A) In a slag reforming method for the purpose of melting low-sulfur steel, a slag-making agent is added after the steel is turned out of the converter, and the slag is vigorously stirred and strongly stirred by a ladle refining method (LF method) or the like. A method of adding a reducing agent such as Al while heating (Method B) is known.
【０００６】[0006]
【発明が解決しようとする課題】前記従来技術のうちＡ
法では、CaCO3 等のガス発生物質の反応による攪拌力を
利用してスラグを混合させることを目的とした方法であ
るが、CaCO3 等のガス発生物質が分解してガスを発生す
る反応は吸熱反応であり、その反応を進行させるために
はある程度以上の熱の供給が必要である。この方法で
は、スラグ還元剤が酸化するときに発生する熱を利用す
るものであるが、その還元剤が酸化するに必要な取鍋ス
ラグ中のＴ・Fe、MnO の酸素ポテンシャルが低い場合あ
るいはスラグ表面が固化している場合にはその還元剤の
酸化反応が不十分となるという問題点がある。The prior art A
The law is a method for the purpose of mixing the slag by utilizing the stirring force due to reaction of the gas generating material, such as CaCO 3, the reaction gas generating material, such as CaCO 3 is decomposing and generating an gas This is an endothermic reaction, and a certain amount of heat supply is required to advance the reaction. In this method, the heat generated when the slag reducing agent is oxidized is used. However, when the oxygen potential of T.Fe and MnO in the ladle slag necessary for the oxidizing of the reducing agent is low, or when the slag When the surface is solidified, there is a problem that the oxidation reaction of the reducing agent becomes insufficient.
【０００７】そのためにCaCO3 等のガス発生物質の反応
が進行しないのでスラグが攪拌されず当初のスラグ改質
の目的が達成されないことが頻繁に起こる。しかも改質
剤及びガス発生物質が未反応のまま２次精錬工程に移る
とスラグのフォーミング（ノロ沸き）や粉塵、煙の発生
等の操業阻害が生じることになる。また前記Ｂ法では、
スラグおよび溶鋼の昇温、攪拌を行う必要があり、全処
理工程が複雑でかつ時間がかかることなどから、取鍋耐
火物の溶損が激しく耐火物原単価が高いものとなる。さ
らに昇熱のための電力コストや電極等の消耗品コストも
高くなるという問題点がある。As a result, the reaction of the gas-generating substance such as CaCO 3 does not progress, so that the slag is not agitated and the initial purpose of slag reforming is often not achieved. In addition, if the process proceeds to the secondary refining step with the reforming agent and the gas generating substance remaining unreacted, slag forming (slag boiling), dust and smoke generation, etc., will impede the operation. In the method B,
Since the slag and the molten steel must be heated and stirred, and the entire treatment process is complicated and time-consuming, the ladle refractory is severely melted and the unit price of the refractory raw material is high. Further, there is a problem that the cost of power for heating up and the cost of consumables such as electrodes also increase.
【０００８】本発明は前記従来技術の問題点を解決し、
取鍋による２次精錬に供する溶鋼上に浮上する取鍋スラ
グを効率よく改質することを目的とするものである。[0008] The present invention solves the problems of the prior art,
An object of the present invention is to efficiently reform ladle slag floating on molten steel to be subjected to secondary refining using a ladle.
【０００９】[0009]
【課題を解決するための手段】前記目的を達成するため
の本発明は、製鋼炉から取鍋へ出鋼開始直後の溶鋼上に
浮上している高温の取鍋スラグに１段階目のスラグ還元
剤を添加し、前記１段階目のスラグ還元剤の添加直後に
CaOを添加することによって滓化を促進しつつ取鍋スラ
グの組成が低融点域となる CaO（％）／Al2O3 （％）＝
1.0〜 1.1に調整する一方、出鋼後の取鍋スラグ上に２
段階目のスラグ還元剤を添加し、次いでガス発生物質を
添加して取鍋スラグを攪拌することを特徴とするスラグ
の改質方法である。SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a first-stage slag reduction to a high-temperature ladle slag floating on molten steel immediately after the start of tapping from a steelmaking furnace to a ladle. Immediately after the addition of the first-stage slag reducing agent.
CaO (%) / Al 2 O 3 (%) = The composition of the ladle slag is in the low melting range while promoting the slagging by adding CaO.
While adjusting to 1.0 to 1.1, 2
Add the stage slag reducing agent and then remove the gas generating material
A method of modifying the slag, characterized in agitation to Rukoto the ladle slag added.
【００１０】[0010]
【作用】スラグ改質の目的は、スラグ中の FeO、MnO な
どを還元させ酸素ポテンシャルの充分に低いスラグを溶
製すること、また低硫鋼溶製時に必要な、酸素ポテンシ
ャルが低く、かつ塩基度が高く、しかも流動性の良いス
ラグを溶製することなどがある。本発明では転炉等の製
鋼炉からの出鋼中と出鋼後とにスラグ還元剤を分割して
添加することにより効果的にスラグの改質を行う。すな
わち具体的には出鋼開始直後における出鋼中の取鍋スラ
グの温度が高く、粘性が低く、酸素ポテンシャル（FeO
、MnO など）が高いときに１段階目のスラグ還元剤を
添加し、一気に反応させる。その直後に CaOを添加する
と、スラグ還元剤の酸化反応熱によりCaOの滓化が促進
され、取鍋スラグは十分に混合される。このようなスラ
グ還元剤と CaOとの添加により、取鍋スラグの組成が最
も低融点域となる CaO（％）／Al2O3 （％）＝1.0 〜1.
1 に調整されると共に取鍋スラグの塩基度を高くするこ
とができる。[Function] The purpose of slag reforming is to reduce slag with sufficiently low oxygen potential by reducing FeO, MnO, etc. in slag, and to reduce the oxygen potential and base required for low sulfur steel melting. For example, slag having a high degree of fluidity and good fluidity may be melted. In the present invention, slag reforming is effectively performed by dividingly adding a slag reducing agent during and after tapping from a steelmaking furnace such as a converter. Specifically, the temperature of the ladle slag during tapping immediately after tapping is high, the viscosity is low, and the oxygen potential (FeO
, MnO, etc.) is high, the first-stage slag reducing agent is added and reacted at once. Immediately after that, if CaO is added, slag formation of CaO is promoted by the heat of oxidation reaction of the slag reducing agent, and the ladle slag is sufficiently mixed. The addition of such a slag reducing agent and CaO, CaO (%) of the composition of the ladle slag is lowest melting zone / Al 2 O 3 (%) = 1.0 ~1.
It can be adjusted to 1 and raise the basicity of ladle slag.
【００１１】出鋼後、さらに２段階目のスラグ還元剤を
添加することで、取鍋スラグ中の酸素ポテンシャルを十
分に低下させることができると共に、出鋼中に取鍋スラ
グを低融点化させてあるため、出鋼後のスラグ還元剤は
反応しやすくなり効率的に取鍋スラグ中のポテンシャル
を低下できる。これによって溶鋼中のAl滓化による清浄
度低下を防止できることになる。After tapping, by further adding a second-stage slag reducing agent, the oxygen potential in the ladle slag can be sufficiently reduced, and the melting point of the ladle slag can be reduced during tapping. Therefore, the slag reducing agent after tapping easily reacts, and the potential in the ladle slag can be efficiently reduced. As a result, it is possible to prevent a decrease in cleanliness due to the formation of Al slag in molten steel.
【００１２】前述のようなスラグ改質処理により２次精
錬前の取鍋スラグは、（１）低酸素ポテンシャル｛取鍋
スラグ中の FeO（％）＋ MnO（％）≦ 1.0％｝、（２）
高塩基度かつ流動性良好｛取鍋スラグ中の CaO（％）／
（SiO2（％）＋Al2O3 （％））｝＝0.25〜0.35を得るこ
とができる。溶鋼の低酸素化を目的とした場合は（１）
が必要で、低硫化を目的とする場合は（１）＋（２）が
必要となるが、いずれも容易にクリアできる。また常に
反応性の良い状態にスラグ組成を調整するため、未反応
の還元剤や、ガス発生物質が二次精錬工程で反応するこ
とにより起こるスラグフォーミング（ノロ沸き）や粉
塵、煙の発生などの操業を阻害する問題も起こらない。
また低コストでプロセスの簡略化も可能となる。The ladle slag before the secondary refining by the slag reforming treatment as described above has the following advantages. (1) Low oxygen potential {FeO (%) in ladle slag + MnO (%) ≦ 1.0%}, (2) )
High basicity and good fluidity CaO (%) in ladle slag
(SiO 2 (%) + Al 2 O 3 (%))｝ = 0.25 to 0.35 can be obtained. When the purpose is to reduce oxygen in molten steel (1)
(1) + (2) is required when the purpose is low sulfurization, but both can be easily cleared. In addition, since the slag composition is always adjusted to a highly reactive state, unreacted reducing agents and slag forming (slag boiling) caused by the reaction of gas-generating substances in the secondary refining process, dust, smoke, etc. There is no problem that hinders operations.
Also, the process can be simplified at low cost.
【００１３】[0013]
【実施例】以下、本発明の実施例を図面に従って説明す
る。実施例１ 低酸素鋼を溶製するに当り、転炉で吹錬した成分組成Ｃ
＝0.05％、Si＝tr、Mn＝0.14％、Ｐ＝0.015 ％、Ｓ＝0.
007 ％、〔Ｏ〕＝560ppmの溶鋼を温度1642℃で出鋼中に
図１に示すように出鋼開始１分後に１段階目のスラグ還
元剤としてAl灰（Al＝55％、Al2O3 ＝30％、SiO2＝10
％）を 0.5kg／Ｔ・Ｓ（スラグ）取鍋スラグ上に添加し
た。Al灰を添加後にAl灰中のAlと取鍋スラグの(FeO) 、
(MnO) との発熱反応により取鍋スラグの温度が上昇する
ので、その直後にフラックスとして（CaO ）を 1.0kg／
Ｔ・Ｓを添加した、その後、脱酸用のAl（金属アルミニ
ウム）を0.9kg ／Ｔ・Ｓ投入し、その３分後出鋼を終了
した。出鋼終了時の取鍋内のスラグ組成を表１に示す。Embodiments of the present invention will be described below with reference to the drawings. Example 1 Component composition C blown in a converter for melting low oxygen steel
= 0.05%, Si = tr, Mn = 0.14%, P = 0.015%, S = 0.
As shown in FIG. 1, one minute after the start of tapping, Al ash (Al = 55%, Al 2 O) was used as a slag reducing agent in the first stage. 3 = 30%, SiO 2 = 10
%) Was added to 0.5 kg / TS (slag) ladle slag. After adding Al ash, (FeO) of Al and Ladle slag in Al ash,
The temperature of the ladle slag rises due to the exothermic reaction with (MnO).
After addition of TS, 0.9 kg / TS of Al (metallic aluminum) for deoxidation was added, and after 3 minutes, tapping was finished. Table 1 shows the slag composition in the ladle at the end of tapping.
【００１４】[0014]
【表１】 [Table 1]
【００１５】出鋼終了後、さらに取鍋スラグの酸素ポテ
ンシャルを低下させるために２段階目のスラグ還元剤と
してAl灰を 0.5kg／Ｔ・Ｓ添加した。そのとき、取鍋ス
ラグの融点が低いために表面は硬化していないのですぐ
に反応した。Al灰添加約30秒後にさらにスラグ攪拌用の
ガス発生物質である炭酸カルシウム CaCO3を 0.5kg／Ｔ
・Ｓおよび CaOを 1.0kg／Ｔ・Ｓ添加した。攪拌後の取
鍋スラグ組成は表２に示すように FeO、MnO は低く低酸
素ポテンシャルが得られた。After the end of tapping, 0.5 kg / TS of Al ash was added as a second-stage slag reducing agent in order to further reduce the oxygen potential of the ladle slag. At that time, since the surface was not hardened because the melting point of the ladle slag was low, it reacted immediately. Approximately 30 seconds after the addition of Al ash, 0.5 kg / T of calcium carbonate CaCO 3 , a gas generating substance for slag stirring, was further added.
-S and CaO were added at 1.0 kg / TS. As shown in Table 2, the ladle slag composition after stirring was low in FeO and MnO, and a low oxygen potential was obtained.
【００１６】[0016]
【表２】 [Table 2]
【００１７】その後、溶鋼とRH脱ガス処理（15分）して
得られた溶鋼の成分組成は次のとおりであり、低酸素鋼
を効率よく製造できた。Ｃ＝0.05％、Si＝tr、Mn＝0.22
％、Ｐ＝0.016 ％、Ｓ＝0.006 ％、 Sol Al ＝0.018
％、Ｔ〔Ｏ〕＝16ppm 。実施例２ 低硫鋼を溶製する前の転炉から取鍋に出鋼した成分組成
Ｃ＝0.05％、Si＝tr、Mn＝0.15％、Ｐ＝0.010 ％、Ｓ＝
0.004 ％、〔Ｏ〕＝520ppmの溶鋼を1654℃で出鋼中に出
鋼後１分の時点で取鍋スラグに１段階目のスラグ還元剤
としてAl灰（実施例１と同成分）を 0.5kg／Ｔ・Ｓ添加
し、その直後CaO 1.0kg ／Ｔ・Ｓ、Al（金属）＝0.55kg
／Ｔ・Ｓ、FeSi＝ 0.3kg／Ｔ・Ｓ、FeMn＝15.0kg／Ｔ・
Ｓを続けて添加した。出鋼終了時の取鍋内スラグ組成を
表３に示す。Thereafter, the composition of the molten steel obtained by subjecting the molten steel to RH degassing (15 minutes) was as follows, and low-oxygen steel could be produced efficiently. C = 0.05%, Si = tr, Mn = 0.22
%, P = 0.016%, S = 0.006%, Sol Al = 0.018
%, T [O] = 16 ppm. Example 2 Before the low sulfur steel was melted, the composition of the components discharged from the converter to the ladle was C = 0.05%, Si = tr, Mn = 0.15%, P = 0.010%, and
0.004%, [O] = 520 ppm molten steel during tapping at 1654 ° C 1 minute after tapping, 0.5 minute of Al ash (same component as in Example 1) was added to the ladle slag as a first-stage slag reducing agent. kg / TS added, immediately afterwards CaO 1.0kg / TS, Al (metal) = 0.55kg
/ TS ・ FeSi = 0.3kg / TS ・ FeMn = 15.0kg / TS ・
S was subsequently added. Table 3 shows the slag composition in the ladle at the end of tapping.
【００１８】[0018]
【表３】 [Table 3]
【００１９】また出鋼直後、取鍋スラグをさらに還元す
る目的でAl灰を 1.0kg／Ｔ・Ｓ添加し、そのAl灰の反応
が終了するとき（Al灰添加30秒後）炭酸カルシウム CaC
O3 0.5kg／Ｔ・Ｓを添加した（塩基度調整のため）。そ
の20秒後にフラックス CaOを1.8kg／Ｔ・Ｓさらに添加
した。その後の取鍋スラグ組成は表４に示すように Fe
O、MnO が低く低酸素ポテンシャルとなった。Immediately after tapping, 1.0 kg / TS of Al ash is added to further reduce the ladle slag, and when the reaction of the Al ash is completed (30 seconds after the addition of Al ash), calcium carbonate CaC
O 3 0.5 kg / TS was added (for adjusting the basicity). Twenty seconds later, 1.8 kg / TS of flux CaO was further added. The ladle slag composition after that is as shown in Table 4
O and MnO were low, resulting in low oxygen potential.
【００２０】[0020]
【表４】 [Table 4]
【００２１】溶鋼はその後RH処理され、またRH処理中 C
aO粉吹込みにより脱硫処理された。脱硫処理後の溶鋼組
成は以下の通りであり、低硫鋼を効率よく製造できた。
Ｃ＝0.11％、Si＝0.20％、Mn＝1.25％、Ｐ＝0.012 ％、
Ｓ＝0.0012％、Sol Al＝0.045 ％、Ｔ〔Ｏ〕＝10ppm 。
本発明により以下の２点が可能になった。The molten steel is then subjected to RH treatment, and during the RH treatment C
It was desulfurized by blowing aO powder. The composition of the molten steel after the desulfurization treatment was as follows, and a low-sulfur steel could be produced efficiently.
C = 0.11%, Si = 0.20%, Mn = 1.25%, P = 0.012%,
S = 0.012%, Sol Al = 0.045%, T [O] = 10 ppm.
The present invention has made the following two points possible.
【００２２】（１）取鍋スラグの酸素ポテンシャルを低
レベル｛取鍋スラグ中 FeO（％）＋MnO （％）≦ 1.0
％｝に調整できRHやArバブリング処理時あるいは取鍋滞
留中の取鍋スラグからの溶鋼再酸化を抑えることができ
るようになった。それにより低酸素高洗浄高の溶製が可
能になった。図２には取鍋スラグ中 FeO（％）＋ MnO
（％）と連鋳タンディッシュ溶鋼のＴ〔Ｏ〕(ppm) との
関係を、図３には連鋳タンディッシュ溶鋼の代走Ｔ
〔Ｏ〕(ppm) と成品の欠陥指数（冷延材のふくれ、スリ
バー等に対応）の関係を示す。(1) Low level of oxygen potential of ladle slag 低 FeO (%) + MnO (%) ≦ 1.0 in ladle slag
%｝, And the reoxidation of molten steel from ladle slag during RH or Ar bubbling treatment or during ladle retention can be suppressed. This has made it possible to produce low oxygen and high washing height. Figure 2 shows FeO (%) + MnO in ladle slag
(%) And T [O] (ppm) of the continuous cast tundish molten steel, and FIG.
The relationship between [O] (ppm) and the defect index of the product (corresponding to blistering of cold rolled material, sliver, etc.) is shown.
【００２３】（２）図２に示すように本発明法によれ
ば、従来法に比較して取鍋スラグの酸素ポテンシャルの
低下｛ FeO（％）＋ MnO（％）≦１％｝により溶鋼のＴ
〔Ｏ〕(ppm) を低減できる。かつ塩基度が高く流動性が
高い域｛ CaO（％）／（SiO2（％）＋Al2O3 （％））＝
0.25〜0.35｝に調整することができたため、RH処理など
の２次精錬工程で行う脱硫処理において高脱硫率を得る
ことができる。(2) As shown in FIG. 2, according to the method of the present invention, the lowering of the oxygen potential of the ladle slag {FeO (%) + MnO (%) ≦ 1%} as compared with the conventional method, T
[O] (ppm) can be reduced. And high-frequency high fluidity basicity {CaO (%) / (SiO 2 (%) + Al 2 O 3 (%)) =
Since it could be adjusted to 0.25 to 0.35 °, a high desulfurization rate can be obtained in the desulfurization treatment performed in the secondary refining process such as the RH treatment.
【００２４】図４には取鍋スラグ中 FeO（％）＋MnO
（％）と溶鋼の脱硫率の関係｛但し、脱硫率（％）＝
｛（脱硫処理前〔Ｓ〕(ppm) −脱硫処理後〔Ｓ〕(ppm)
）／脱硫処理前〔Ｓ〕(ppm) ｝× 100｝を、図５には
取鍋スラグ中 CaO（％）／（SiO2（％）＋Al2O
3 （％））と脱硫率の関係を示す。図４に示すように本
発明法によれば従来法に比較して取鍋スラグの FeO
（％）＋ MnO（％）を大幅に低下することができるので
溶鋼の脱硫率を向上するこができることが分かる。また
図５に示すように本発明法によれば従来法に比較して取
鍋スラグの塩基度 CaO（％）／（SiO2（％）＋Al2O
3 （％））を大きくすることができるので溶鋼の脱硫率
を向上することができる。FIG. 4 shows FeO (%) + MnO in ladle slag.
(%) And desulfurization rate of molten steel. However, desulfurization rate (%) =
｛(Before desulfurization [S] (ppm)-After desulfurization [S] (ppm)
) / Before desulfurization treatment [S] (ppm) {× 100}, Fig. 5 shows CaO (%) / (SiO 2 (%) + Al 2 O in ladle slag
3 (%)) and the desulfurization rate. As shown in FIG. 4, according to the method of the present invention, the ladle slag FeO
(%) + MnO (%) can be greatly reduced, so that the desulfurization rate of the molten steel can be improved. Also, as shown in FIG. 5, according to the method of the present invention, the basicity of ladle slag CaO (%) / (SiO 2 (%) + Al 2 O, as compared with the conventional method.
3 (%)), the desulfurization rate of molten steel can be improved.
【００２５】[0025]
【発明の効果】以上説明したように本発明によれば、製
鋼炉から取鍋内に出鋼中の溶鋼上に浮上している高温の
取鍋スラグに１段目のスラグ還元剤を添加して取鍋スラ
グの酸素ポテンシャルを一応下げると共に、その直後の
CaOの添加による滓化促進により低融点域のスラグ組成
並びに塩基度の向上を達成する。出鋼後の取鍋スラグ上
に低融点でかつ塩基度を向上した取鍋スラグに２段階目
のスラグ還元剤を添加して取鍋スラグの酸素ポテンシャ
ルを低下してあるので、２次精錬における溶鋼の低酸化
が容易となり、また溶鋼の脱硫率を向上させることがで
きる。As described above, according to the present invention, the first-stage slag reducing agent is added to the high-temperature ladle slag floating on the molten steel during tapping from the steelmaking furnace into the ladle. While reducing the oxygen potential of the ladle slag for the time being,
The promotion of slag formation by the addition of CaO achieves an improvement in slag composition and basicity in the low melting point region. The second stage slag reducing agent is added to the ladle slag with low melting point and improved basicity on the ladle slag after tapping to reduce the oxygen potential of the ladle slag. Low oxidation of the molten steel becomes easy, and the desulfurization rate of the molten steel can be improved.
【図１】本発明の実施例１における処理フローを示す説
明図である。FIG. 1 is an explanatory diagram showing a processing flow in a first embodiment of the present invention.
【図２】取鍋スラグの酸素ポテンシャルと連鋳タンディ
ッシュ溶鋼のＴ〔Ｏ〕ppm の関係を示すグラフである。FIG. 2 is a graph showing the relationship between the oxygen potential of a ladle slag and T [O] ppm of a continuously cast tundish molten steel.
【図３】連鋳タンディッシュ溶鋼のＴ〔Ｏ〕ppm と成品
の欠陥指数の関係を示すグラフである。FIG. 3 is a graph showing the relationship between T [O] ppm of a continuously cast tundish molten steel and a defect index of a product.
【図４】取鍋スラグ中の FeO（％）＋ MnO（％）と溶鋼
の脱硫率の関係を示すグラフである。FIG. 4 is a graph showing the relationship between FeO (%) + MnO (%) in ladle slag and the desulfurization rate of molten steel.
【図５】取鍋スラグ中の CaO（％）／（SiO2（％）＋Al
2O3 （％））と脱硫率の関係を示すグラフである。Fig. 5 CaO (%) / (SiO 2 (%) + Al in ladle slag
3 is a graph showing the relationship between 2 O 3 (%)) and the desulfurization rate.
───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.7，ＤＢ名) C21C 7/00,7/04,7/076 ＪＩＣＳＴファイル（ＪＯＩＳ)────────────────────────────────────────────────── ─── Continued on the front page (58) Fields surveyed (Int. Cl. 7 , DB name) C21C 7/00, 7/04, 7/076 JICST file (JOIS)
Claims (1)
に浮上している高温の取鍋スラグに１段階目のスラグ還
元剤を添加し、前記１段階目のスラグ還元剤の添加直後
に CaOを添加することによって滓化を促進しつつ取鍋ス
ラグの組成が低融点域となる CaO（重量％）／Al2O
3 （重量％）＝ 1.0〜 1.1に調整する一方、出鋼後の取
鍋スラグ上に２段階目のスラグ還元剤を添加し、次いで
ガス発生物質を添加して取鍋スラグを攪拌することを特
徴とするスラグの改質方法。1. A first-stage slag reducing agent is added to a high-temperature ladle slag floating on molten steel immediately after the start of tapping from a steelmaking furnace to a ladle, and the first-stage slag reducing agent is added. Immediately after the addition of CaO, the composition of the ladle slag becomes a low melting point area while promoting slagging. CaO (wt%) / Al 2 O
3 (% by weight) = 1.0 to 1.1, while adding the second-stage slag reducing agent to the ladle slag after tapping ,
Modifying method of the slag, wherein agitation to Rukoto the ladle slag by the addition of gas generating material.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP05125615A JP3140256B2 (en) | 1993-05-27 | 1993-05-27 | Slag reforming method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP05125615A JP3140256B2 (en) | 1993-05-27 | 1993-05-27 | Slag reforming method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06330138A JPH06330138A (en) | 1994-11-29 |
| JP3140256B2 true JP3140256B2 (en) | 2001-03-05 |
Family
ID=14914470
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP05125615A Expired - Fee Related JP3140256B2 (en) | 1993-05-27 | 1993-05-27 | Slag reforming method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3140256B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3885387B2 (en) * | 1998-10-20 | 2007-02-21 | Ｊｆｅスチール株式会社 | Method for producing ultra-low sulfur steel with excellent cleanability |
| JP4609325B2 (en) * | 2006-01-11 | 2011-01-12 | 住友金属工業株式会社 | Treatment method of molten iron by Nd addition |
| JP5437945B2 (en) * | 2010-07-29 | 2014-03-12 | 株式会社神戸製鋼所 | Method for suppressing deposits in hot repeated tundish |
-
1993
- 1993-05-27 JP JP05125615A patent/JP3140256B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH06330138A (en) | 1994-11-29 |
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