JP2635721B2 - How to prevent slag from flowing out of the converter - Google Patents

How to prevent slag from flowing out of the converter

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Publication number
JP2635721B2
JP2635721B2 JP26564788A JP26564788A JP2635721B2 JP 2635721 B2 JP2635721 B2 JP 2635721B2 JP 26564788 A JP26564788 A JP 26564788A JP 26564788 A JP26564788 A JP 26564788A JP 2635721 B2 JP2635721 B2 JP 2635721B2
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JP
Japan
Prior art keywords
slag
cao
converter
amount
mgo
Prior art date
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JP26564788A
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Japanese (ja)
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JPH02111810A (en
Inventor
英明 山村
秀幸 三隅
敏行 金子
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Nippon Steel Corp
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Nippon Steel Corp
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Description

【発明の詳細な説明】 <産業上の利用分野> 本発明は溶鋼出鋼前に転炉内スラグを固化して出鋼時
に溶鋼に随伴して転炉内スラグが流出するのを防止する
方法に関するものである。
DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention is a method for solidifying slag in a converter before molten steel tapping and preventing slag in the converter from flowing out accompanying the molten steel during tapping. It is about.

<従来の技術> 転炉内スラグが出鋼時に溶鋼と共に流出するとそれ自
体が介在物となる上に、脱酸後の溶鋼酸化源となり、溶
鋼の清浄度が低下する。
<Conventional Technology> When slag in a converter flows out together with molten steel at the time of tapping, the slag itself becomes an inclusion, and also serves as an oxidizing source of molten steel after deoxidation, thereby lowering the cleanliness of the molten steel.

このため従来は、特願昭62−192136号に提案されてい
る様に、スラグのT.Fe量に応じてCaOを添加してスラグ
の塩基度CaO/SiO2を調整し、該スラグを固化し、上記し
た出鋼時の流出を防止して出鋼する方法を採っていた。
Therefore conventionally, as proposed in Japanese Patent Application Sho 62-192136, the addition of CaO in accordance with the T.Fe amount of slag to adjust a basicity CaO / SiO 2 of the slag, solidified the slag However, the above-described method of tapping while preventing outflow during tapping has been adopted.

この方法は第3図に示す如き、転炉内スラグ中のT.Fe
と該スラグの塩基度CaO/SiO2の関係を基に行われてい
る。
This method uses T.Fe in the slag in the converter as shown in Fig.3.
And the basicity of the slag CaO / SiO 2 .

図中の破線は過去の実績から得た固化成否境界線で、
この線から右下の範囲が固化が成功する領域とされてい
る。
The broken line in the figure is the solidification success / failure line obtained from past results.
The lower right area from this line is the area where solidification is successful.

しかしながら固化はT.Fe以外のスラグの組成によって
も条件が異なり、同一T.Feでもスラグの融点を下げるAl
2O3等の濃度が高くなると、スラグ固化に必要な塩基度
は高くなり、これによってCaOは益々多量を必要とし、
その結果転炉内のスラグ量は増大する。
However, the conditions for solidification differ depending on the composition of the slag other than T.Fe.
As the concentration of 2 O 3 and the like increases, the basicity required for slag solidification increases, which requires more and more CaO,
As a result, the amount of slag in the converter increases.

この問題を解決するものとして特開昭63−79910号公
報の提案がある。
To solve this problem, there is a proposal in Japanese Patent Application Laid-Open No. 63-79910.

この提案はそれ自体周知である現象を用いたもので、
MgO自体が高融点酸化物であってCaO−SiO−FeO系スラグ
にMgOを一定限度以上添加すると上記スラグも高融点化
する事を利用して転炉の精錬末期又は終了直後に炉内に
MgOを投入もしくは吹込んで転炉内スラグを高融点化し
て出鋼時の流出を最小に抑えるもので、炉内スラグに加
えるMgO量を該スラグ内のCaO重量の0.3〜0.8重量比とす
るものである。
This proposal uses a phenomenon known per se,
MgO itself is a high melting point oxide, and when MgO is added to a CaO-SiO-FeO-based slag over a certain limit, the slag also increases in melting point, utilizing the fact that the melting point of the slag is increased.
Inject or inject MgO to raise the melting point of the slag in the converter to minimize outflow during tapping, and to set the amount of MgO added to the slag in the furnace to 0.3 to 0.8 weight ratio of the CaO weight in the slag. It is.

<発明が解決しようとする課題> 上記した従来のスラグ固化方法によると、スラグ固化
が安定しない事、これを安定して固化するには多量のCa
Oを必要とする事、その結果スラグ量が増大してスラグ
処理費が増大すると共に、冒頭に述べた目的の達成が困
難になる。これ等の問題を解決するために特開昭63−79
910号公報の提案を用いてもT.Feが高い場合及びSiO
2が高い場合(CaO/SiO2が低い時)はMgO/CaOが0.8でも
炉内スラグは固化しない事がある。
<Problems to be Solved by the Invention> According to the conventional slag solidification method described above, slag solidification is not stable, and a large amount of Ca is required to stabilize it.
O is required, and as a result, the amount of slag increases, the slag processing cost increases, and it is difficult to achieve the above-mentioned purpose. To solve these problems, Japanese Patent Application Laid-Open No. 63-79
In the case of using high T.Fe and SiO
When 2 is high (when CaO / SiO 2 is low), the slag in the furnace may not be solidified even if MgO / CaO is 0.8.

又実施例に記載されているMgO/CaOが0.36の時にT.Fe
が高く、CaO/SiO2が低い時には炉内スラグが固化しない
事があり、炉内スラグの固化が安定しない事がある。こ
の不安定な固化を安定させるには出来るだけMgO/CaO2
高くする事が必要となる。このためT.Feが低い場合や、
或いはCaO/SiO2が高い場合には、それ以下でも固化する
ので余分なMgOを使う事になり処理コストが増大する。
Also, when MgO / CaO described in the examples is 0.36, T.Fe
When CaO / SiO 2 is low, the slag in the furnace may not be solidified, and the solidification of the slag in the furnace may not be stable. In order to stabilize this unstable solidification, it is necessary to increase MgO / CaO 2 as much as possible. For this reason, when T.Fe is low,
Alternatively, when CaO / SiO 2 is high, even if it is lower than that, solidification occurs, so that excess MgO is used and the processing cost increases.

本発明はT.FeやCaO/SiO2更にはAl2O3が変化しても安
定して転炉内スラグを固化すると共に該炉内スラグの固
化費を格段に低減する方法を提供する事を課題とするも
のである。
An object of the present invention is to provide a method for solidifying slag in a converter stably even when T.Fe, CaO / SiO 2, and even Al 2 O 3 change, and significantly reducing the solidification cost of the slag in the furnace. Is the subject.

<課題を解決するための手段> 本発明は上記課題を解決するために、 (1)溶銑の吹錬において、吹錬末期又は吹錬終了後に
転炉内スラグの固相率が30%以上となる量のMgOを転炉
内に添加する事を基本的な手段とし、 (2)溶銑の吹錬において、吹錬末期又は吹錬終了後
に、転炉内スラグのCaO/SiO2及びT.Fe量に応じてMgOを により転炉内に添加する事を具体的な手段とするもので
ある。
<Means for Solving the Problems> To solve the above problems, the present invention provides: (1) In the hot metal blowing, the solid phase ratio of the slag in the converter is 30% or more at the end of blowing or after blowing. The basic means is to add a certain amount of MgO into the converter. (2) In the hot metal blowing, at the end of blowing or after blowing, CaO / SiO 2 and T.Fe MgO according to the amount As a specific means, it is added into the converter.

<作用> 本発明者等は上記課題の解決を目的として種々実験・
検討を繰り返した。
<Operation> The present inventors conducted various experiments to solve the above-mentioned problems.
The examination was repeated.

その結果、前記したそれぞれの従来技術は、転炉内ス
ラグの融点に影響力がある該スラグ成分の中、T.FeとCa
O/SiO2にのみ、又はMgO/CaOにのみ着目し、各々を別々
に検討している事に問題がある事を見出した。
As a result, each of the prior arts described above, T.Fe and Ca among the slag components that have an effect on the melting point of the slag in the converter
We focused on only O / SiO 2 or only MgO / CaO, and found that there was a problem in considering each separately.

本発明者等は実験・検討により、第4図に示す関係を
得た。図はスラグの固相率と取鍋内に流出したスラグ量
の関係を示したものである。
The inventors obtained the relationship shown in FIG. 4 through experiments and studies. The figure shows the relationship between the solid fraction of slag and the amount of slag flowing into the ladle.

ここでスラグの固相率とは、その反応点での各成分値
(サンプリング値)を基に広く当分野で用いられている
方法、例えば標準自由エネルギー、生成の自由エネルギ
ー、活量係数等の熱力学データを用いて、反応点におい
てスラグ中に生成した晶出物(固相)の割合を平衡計算
によって求めた値を言う。
Here, the solid phase ratio of the slag is a method widely used in this field based on each component value (sampling value) at the reaction point, for example, standard free energy, free energy of formation, activity coefficient and the like. A value obtained by calculating the ratio of crystallized substances (solid phase) generated in the slag at the reaction point using thermodynamic data by equilibrium calculation.

本発明者等は図により、転炉内スラグの固化はスラグ
の固相率に基本的に支配されており、この固相率が30%
以上になると、スラグの融点に影響するスラグの成分が
変化しても出鋼時に流出するスラグ量が6kg/ton以下と
著しく減少し、実質的に前記課題の総てが解決出来る事
を見出した。
According to the figures, the inventors found that the solidification of the slag in the converter is basically governed by the solid fraction of the slag, and this solid fraction is 30%.
With the above, even if the composition of the slag affecting the melting point of the slag changes, the amount of slag flowing out during tapping is significantly reduced to 6 kg / ton or less, and it has been found that substantially all of the above problems can be solved. .

次いで本発明者等は、スラグの固相率30%を確立する
に当たって、スラグのT.Fe、CaO/SiO2に応じて必要なス
ラグ固化剤の種類及び量について検討を行った。この検
討で本発明者等は第5図の関係を見出した。
Next, in establishing the solid phase ratio of 30% of the slag, the present inventors examined the type and amount of the slag solidifying agent required according to T.Fe and CaO / SiO 2 of the slag. In this study, the present inventors found the relationship shown in FIG.

CaOによる固化を前提とした場合、第5図に示す固化
限界を示すCaO/SiO2と固化前Al2O3含有量との関係は、
図に明らかな様にT.Feを一定にしても一般的操業範囲に
於いてはAl2O3の含有量の変化に応じて固化限界は大幅
に変化した。
When assuming the solidification by CaO, relationship between CaO / SiO 2 and solidifying before content of Al 2 O 3 showing a solidification limit shown in Fig. 5,
As is evident from the figure, even when T.Fe was kept constant, the solidification limit significantly changed according to the change in the content of Al 2 O 3 in the general operation range.

そこでAl2O3の影響の少ない固化剤について調査し、
第2図に示す知見を得た。
Therefore, we investigated a solidifying agent with little effect of Al 2 O 3 ,
The findings shown in FIG. 2 were obtained.

図は該調査におけるスラグ中のAl2O3濃度と、スラグ
固化剤としてのMgOとCaOの各添加量の関係を整理した結
果を示す。
The figure shows the results of the investigation in which the relationship between the Al 2 O 3 concentration in the slag and the amounts of MgO and CaO added as the slag solidifying agent was determined.

図から実線で示したMgOの添加量は、Al2O3濃度の影響
が小さく、点線で示したCaOの添加量に対して略70%で
良い事が判明した。
From the figure, it was found that the addition amount of MgO shown by the solid line was little affected by the Al 2 O 3 concentration, and was only about 70% of the addition amount of CaO shown by the dotted line.

そこで更に検討を重ねた結果、MgOの必要添加量はCaO
/SiO2によって異なり、又転炉吹錬の一般的範囲ではAl2
O3濃度の変化は1〜5%と小さく、MgOによる固化では
この程度のAl2O3の変化では固化に必要なMgO量の変化は
実質的には生じない事から一般的転炉吹錬では固化のた
めのMgO添加量はT.FeとCaO/SiO2によって決まる事が判
明した。第1図はその関係を示す。
Therefore, as a result of further study, the required addition amount of MgO was CaO
/ SiO 2 and the general range of converter blowing is Al 2
The change in the O 3 concentration is as small as 1 to 5%, and the solidification by MgO does not substantially change the MgO amount required for the solidification by the change of Al 2 O 3. It was found that the amount of MgO added for solidification was determined by T.Fe and CaO / SiO 2 . FIG. 1 shows the relationship.

そこで第1図を基にCaO/SiO2別にMgOの添加量を転炉
内スラグのT.Feとの関係から整理し、 の関係を得た。本発明はこの知見を基になされたもので
ある。
So based on Figure 1 CaO / SiO 2 separately organize the addition amount of MgO from the relationship between T.Fe rolling furnace slag, Got a relationship. The present invention has been made based on this finding.

<実施例> 以下に本発明例を比較例と共に示す。<Examples> Examples of the present invention are shown below together with comparative examples.

(1)使用転炉 上底吹き転炉(340ton/ch) (2)転炉吹止温度 1600℃〜1750℃ (3)吹止成分 〔C〕:0.02 〜0.50% 〔Mn〕:0.2 〜2.0% 〔P〕:0.005〜0.030% 〔S〕:0.001〜0.03% (4)スラグ成分 CaO :35.0〜65.0% FeO : 7.0〜28.0% SiO2 : 5.0〜18.0% MnO : 2.0〜35.0% MgO : 5.0〜10.0% Al2O3: 1.0〜5.0% (5)固化剤の添加方法。(1) Converter used Top and bottom blown converter (340 ton / ch) (2) Converter shutoff temperature 1600 to 1750 ° C (3) Shutoff component [C]: 0.02 to 0.50% [Mn]: 0.2 to 2.0 % (P): 0.005 to 0.030% (S): 0.001 to 0.03% (4) slag component CaO: 35.0~65.0% FeO: 7.0~28.0% SiO 2: 5.0~18.0% MnO: 2.0~35.0% MgO: 5.0 110.0% Al 2 O 3 : 1.0 to 5.0% (5) Addition method of solidifying agent.

溶鋼のサンプルから溶鋼の凝固温度を検出し、これか
ら溶鋼が含有する炭素量を算出し、第6図に示す過去の
実績から求めた溶鋼の炭素含有量とT.Feの関係図からT.
Feを求め、CaO投入量と溶銑及び副原料中のSi成分から
計算されるSiO2発生量からCaO/SiO2を予測し、この値に
応じてスラグの固相率を30%以上にするのに必要なスラ
グ固化剤量を上記関係式で求めて添加した。
The solidification temperature of the molten steel was detected from the sample of the molten steel, the carbon content of the molten steel was calculated from this, and the T.Fe was determined from the relationship between the carbon content of the molten steel and T.Fe obtained from the past results shown in FIG.
Seeking Fe, predict CaO / SiO 2 of SiO 2 generation amount calculated from the CaO dosages and hot metal and Si components in auxiliary materials, for the solid fraction of the slag at least 30% depending on the value The amount of the slag solidifying agent required for the above was determined by the above relational expression and added.

上記T.FeやCaO/SiO2を求めるには計算による他、直接
分析し検出する方法を用いても良い。
In order to obtain T.Fe and CaO / SiO 2 , a method of directly analyzing and detecting may be used in addition to calculation.

処理条件と結果を比較例と共に第1表に示す。 The processing conditions and results are shown in Table 1 together with Comparative Examples.

本発明実施例の試験番号1〜13では(1〜5は3≦Ca
O/SiO2<4,6〜9は4≦CaO/SiO2<5,10〜13は5≦CaO/S
iO2<6の場合)、出鋼時の取鍋へのスラグ流出量は安
定し、MgO/CaOが0.9の5及び0.2の8を含み6kg/ton以下
になった。
In Test Nos. 1 to 13 of the examples of the present invention, (1 to 5 represent 3 ≦ Ca
For O / SiO 2 <4,6-9, 4 ≦ CaO / SiO 2 <5,10-13 for 5 ≦ CaO / S
In the case of iO 2 <6), the amount of slag flowing out to the ladle during tapping was stable, and the MgO / CaO became 0.9 kg or less including 6 and 0.2 to 8 kg / ton or less.

これ等本発明例ではスラグ流出量が激減した結果、取
鍋へのAl添加時のAl歩留が60%以上の高位に安定し、T.
0も25ppm以下に安定して低くなった。尚MgO源としてはM
gO粒を用いても破砕したMgO煉瓦を用いても同様の効果
を得た。
In these examples of the present invention, the slag outflow was drastically reduced, and as a result, the Al yield when Al was added to the ladle was stabilized at a high level of 60% or more.
0 also stably decreased to 25 ppm or less. The MgO source is M
Similar effects were obtained using gO grains or crushed MgO bricks.

一方、CaOを添加してスラグ固化を行った比較例の試
験番号14〜17に於いて15〜17はMgOの場合と同様の効果
を得たが、多量のスラグ固化剤を必要とした。又14はT.
FeとCaOの関係では固化する領域に入っているが、Al2O3
が5%と高かったため流出スラグ量が増加した。
On the other hand, in Test Nos. 14 to 17 of Comparative Examples in which CaO was added and slag was solidified, 15 to 17 obtained the same effect as that of MgO, but required a large amount of slag solidifying agent. 14 is T.
In the relationship between Fe and CaO, it is in the solidification region, but Al 2 O 3
Was as high as 5%, and the amount of slag flowing out increased.

又、MgOを添加しなかった比較例の19、21、23及びMgO
を添加したもののスラグ組成が固化領域に入っていなか
った比較例の18、20、22、24では出鋼時の取鍋へのスラ
グ流出量は10kg/ton以上に達し、その結果Al歩留は50%
以下に低下し、T.Oは35ppm以上となり溶鋼の清浄度が低
下した。
Also, Comparative Examples 19, 21, 23 and MgO to which no MgO was added
In Comparative Examples 18, 20, 22, and 24 in which the slag composition was not included in the solidification region, the slag outflow to the ladle during tapping reached 10 kg / ton or more, and as a result, the Al yield was increased. 50%
The TO decreased to 35 ppm or more, and the cleanliness of the molten steel decreased.

又比較例の18、20、22、24はMgO/CaOが0.3〜0.8の範
囲にあったが炉内スラグは満足に固化せず、流出スラグ
量は10kg/Tを超えた。
In Comparative Examples 18, 20, 22, and 24, MgO / CaO was in the range of 0.3 to 0.8, but the slag in the furnace did not solidify satisfactorily, and the outflow slag amount exceeded 10 kg / T.

<発明の効果> 本発明は、溶銑吹錬末期又は終了後に転炉内スラグの
T.Fe及びCaO/SiO2を求め、これを基にスラグ固相率が30
%以上になるスラグ固化剤として必要なMgO量を添加す
るので従来のCaO又はMgOの添加によるスラグ固化に比し
て、必要固化剤量が少なくなるにもかかわらず、スラグ
固化は安定して溶鋼取鍋に流出するスラグ量は大幅に低
減する。これにより合金歩留は向上し、更に溶鋼の清浄
度が格段に向上する等もたらす効果は大きい。
<Effects of the Invention> The present invention relates to the production of slag in a converter at the end of or after the end of hot metal blowing.
T. Fe and CaO / SiO 2 were determined, and based on this, the slag solid fraction was 30
% Of the required slag solidifying agent is added, so that the slag solidification is stable even though the required amount of solidifying agent is smaller compared to the conventional slag solidification by adding CaO or MgO. The amount of slag flowing into the ladle is greatly reduced. As a result, the yield of the alloy is improved, and the cleanliness of the molten steel is significantly improved.

【図面の簡単な説明】[Brief description of the drawings]

第1図はスラグ固相率30%以上を達成するMgO量とCaO/S
iO2量の関係を示し、第2図はスラグ固相率30%以上を
達成するMgO量とAl2O3量の関係及びCaO量とAl2O3量の関
係を示し、第3図はスラグのT.Feと塩基度の関係を示
す。 第4図はスラグの固相率と取鍋への流出スラグ量の関係
を示し、第5図はスラグの吹止前Al2O3量と塩基度の関
係を示し、第6図は吹止時炭素量とT.Feの関係を示す図
である。
Fig. 1 shows the amount of MgO and CaO / S to achieve a slag solid fraction of 30% or more.
indicates iO 2 of relationship, FIG. 2 shows the relationship between the content of MgO and the amount of Al 2 O 3 of relationship and the amount of CaO and the amount of Al 2 O 3 to achieve 30% or more slag solid phase ratio, FIG. 3 is 4 shows the relationship between T.Fe of slag and basicity. Figure 4 shows the relationship between the outflow amount of slag in the ladle and solid fraction of the slag, FIG. 5 shows the relationship between吹止previous amount of Al 2 O 3 and basicity of the slag, FIG. 6 is吹止It is a figure which shows the relationship between hourly carbon amount and T.Fe.

───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭62−40308(JP,A) 特開 昭62−37307(JP,A) 特公 昭62−1444(JP,B2) ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-40308 (JP, A) JP-A-62-37307 (JP, A) JP-B-62-1444 (JP, B2)

Claims (2)

(57)【特許請求の範囲】(57) [Claims] 【請求項1】溶銑の吹錬において、吹錬末期又は吹錬終
了後に、転炉内スラグの固相率が30%以上となる量のMg
Oを転炉内に添加しスラグを固化する事を特徴とする転
炉内スラグの流出防止方法。
Claims 1. In the blowing of hot metal, at the end of blowing or after finishing blowing, the amount of Mg in which the solid phase ratio of slag in the converter becomes 30% or more.
A method for preventing slag from flowing out of a converter, characterized by adding O into the converter to solidify the slag.
【請求項2】溶銑の吹錬において、吹錬末期又は吹錬終
了後に、転炉内スラグのCaO/SiO2及びT.Fe量に応じて、 のMgOを転炉内に添加しスラグを固化する事を特徴とす
る転炉内スラグの流出防止方法。
2. In the hot metal blowing, at the end of blowing or after blowing, depending on the amount of CaO / SiO 2 and T.Fe in the slag in the converter, A method for preventing slag from flowing out of a converter, characterized by adding MgO into the converter to solidify the slag.
JP26564788A 1988-10-20 1988-10-20 How to prevent slag from flowing out of the converter Expired - Lifetime JP2635721B2 (en)

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