JP2002327207A - Method for dephosphorizing molten pig iron by using converter - Google Patents
Method for dephosphorizing molten pig iron by using converterInfo
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- JP2002327207A JP2002327207A JP2001134069A JP2001134069A JP2002327207A JP 2002327207 A JP2002327207 A JP 2002327207A JP 2001134069 A JP2001134069 A JP 2001134069A JP 2001134069 A JP2001134069 A JP 2001134069A JP 2002327207 A JP2002327207 A JP 2002327207A
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- Prior art keywords
- converter
- hot metal
- pig iron
- molten pig
- ratio
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- 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.)
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- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
- Carbon Steel Or Casting Steel Manufacturing (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】この発明は、転炉を用いた溶
銑の脱りん処理、とりわけホタル石等の融点降下剤を用
いることなく溶銑の脱りん処理を可能とした、環境規制
に適応した技術に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technology adapted to environmental regulations, which enables dephosphorization of hot metal using a converter, in particular, dephosphorization of hot metal without using a melting point depressant such as fluorite. It is about.
【０００２】[0002]
【従来の技術】近年、鋼板に対する要求性能が高度にな
るにともない、溶銑段階におけるりんや硫黄の低減が要
求されている。このため、従来は主に転炉のみで行って
いた、溶銑の脱珪、脱りんおよび脱硫処理を脱炭工程に
先だって行う、いわゆる溶銑予備処理を行うことが普及
してきている。この溶銑予備処理は、脱炭工程の付加を
軽減するだけでなく、製鋼工程におけるトータルコス卜
の低減および発生スラグ量の低減などをはかれる利点も
ある。2. Description of the Related Art In recent years, as the required performance of steel sheets has become higher, it has been required to reduce phosphorus and sulfur in the hot metal stage. For this reason, the so-called hot metal pretreatment, which is conventionally mainly performed only in the converter and performs the desiliconization, dephosphorization and desulfurization processes of the hot metal prior to the decarburization step, has become widespread. This hot metal pretreatment not only reduces the addition of the decarburization step, but also has the advantage of reducing the total cost and the amount of generated slag in the steelmaking step.
【０００３】一方、最近になり、地球環境を保全する観
点から、環境に与える負荷の大きい、フッ素やナトリウ
ムの使用を極力控えることが要望されてきている。従っ
て、製鋼工程において融点を下げるための添加剤や脱硫
剤としてよく使用される、フッ素を含有するホタル石
や、ナトリウムを含有するソーダ灰は、その使用を抑制
することが求められている。On the other hand, recently, from the viewpoint of preserving the global environment, there has been a demand for minimizing the use of fluorine and sodium, which have a large impact on the environment. Therefore, it is required to suppress the use of fluorine-containing fluorite and sodium-containing soda ash, which are often used as additives or desulfurizing agents for lowering the melting point in the steelmaking process.
【０００４】ここで、溶銑の予備処理工程のうち、脱り
ん処理は、転炉や取鍋、或いはトピードカーを反応容器
として、酸素源やCaO源を投入して実施されるのが一般
的である。この脱りん反応は酸化反応であり、溶融スラ
グとメタルと間の反応により進行する。従って、特に反
応容器として転炉を用いた場合は、炉内のフリーボード
（溶銑表面と容器上面との間の空間）が大きく、酸素投
入速度を大きくできるため、脱りん処理に有利である。[0004] In the pretreatment process of the hot metal, the dephosphorization process is generally carried out by using a converter, a ladle, or a topped car as a reaction vessel and supplying an oxygen source or a CaO source. . This dephosphorization reaction is an oxidation reaction, and proceeds by a reaction between the molten slag and the metal. Therefore, particularly when a converter is used as a reaction vessel, the free board (space between the hot metal surface and the upper surface of the vessel) in the furnace is large and the oxygen injection rate can be increased, which is advantageous for the dephosphorization treatment.
【０００５】例えば、特開平11−269524号公報には、底
吹き攪拌と上吹き酸素とによりスラグおよびメタルの攪
拌を行い、両者の混合を促進する方法が開示されてい
る。しかし、この方法では、脱りん率が不充分であり、
低りん溶銑の溶製は困難である。また、ホタル石使用量
として１kg／t未満が好ましいとの記載があり、ホタル
石の使用を完全に中止するための技術ではない。For example, Japanese Patent Application Laid-Open No. 11-269524 discloses a method in which slag and metal are agitated by bottom-blowing agitation and top-blown oxygen to promote the mixing of both. However, in this method, the dephosphorization rate is insufficient,
It is difficult to produce low phosphorus hot metal. Further, it is described that the amount of fluorite used is preferably less than 1 kg / t, and this is not a technique for completely stopping the use of fluorite.
【０００６】また、特開平11−269522号公報には、A12O
3を用いる技術が開示されている。しかし、A12O3を用い
ると、転炉の炉体耐火物保護のために実施するスラグコ
ーティングで生成した耐火物表面の保護層における、溶
融剥離が促進され、炉の寿命を低下することが問題にな
る。[0006] Japanese Patent Application Laid-Open No. 11-269522 discloses A1 2 O
The technology using 3 is disclosed. However, when A1 2 O 3 is used, melting and exfoliation in the protective layer on the refractory surface generated by slag coating performed for protection of the furnace body refractory of the converter may be promoted, and the life of the furnace may be shortened. It becomes a problem.
【０００７】さらに、特開平1−188613号公報には、非
脱炭酸素効率の推移から吹錬条件を適正化し、スラグの
滓化状態を制御することが開示されている。さらにま
た、特開昭60−169506号公報には、滓化率を向上させる
ためにSiO2源を投入することが開示されている。しか
し、これらの技術は、脱珪および脱りん処理後の溶銑の
脱炭処理に関するものであり、処理中の温度、成分組成
等が大きく異なり、溶銑の脱りん処理に適用することは
難しいものである。Further, Japanese Patent Application Laid-Open No. 1-188613 discloses that the blowing conditions are optimized from the transition of non-decarbonation efficiency to control the slag slagging state. Furthermore, Japanese Patent Application Laid-Open No. 60-169506 discloses that an SiO 2 source is introduced in order to improve the slagging rate. However, these techniques are related to the decarburization treatment of hot metal after desiliconization and dephosphorization treatment, and the temperature, component composition, etc. during the treatment are greatly different, and it is difficult to apply to dephosphorization treatment of hot metal. is there.
【０００８】[0008]
【発明が解決しようとする課題】そこで、この発明は、
ホタル石等の融点降下剤を使用することなく、りん濃度
の低い溶銑を溶製し得る方法について提案することを目
的とする。SUMMARY OF THE INVENTION Therefore, the present invention
An object of the present invention is to propose a method capable of smelting hot metal having a low phosphorus concentration without using a melting point depressant such as fluorite.
【０００９】[0009]
【課題を解決するための手段】この発明は、転炉に装入
した溶銑にフラックスを供給するとともに、酸素ガスを
上吹きして溶銑の予備処理を行うに当り、転炉に装入し
た溶銑の表面積ＳMと、該溶銑の表面における酸素ガス
の吹き付け面積ＳGとの比ＳG／ＳMを0.05〜0.30、かつ
酸素ガス流量を0.5〜2.5m3(標準状態)／t・minに制御し
て、溶銑中のりん濃度を0.040mass％以下に調整するこ
とを特徴とする転炉を用いた溶銑の脱りん方法である。SUMMARY OF THE INVENTION The present invention relates to a method for supplying flux to hot metal charged in a converter and pre-treating the hot metal by blowing oxygen gas upward. The ratio of the surface area S M of the hot metal to the area S G of spraying oxygen gas on the surface of the hot metal S G / S M is 0.05 to 0.30, and the oxygen gas flow rate is 0.5 to 2.5 m 3 (standard state) / t · min. This is a method for dephosphorizing hot metal using a converter, wherein the method controls and adjusts the phosphorus concentration in the hot metal to 0.040 mass% or less.
【００１０】また、上記の脱りん方法において、溶銑中
のりん濃度が0.040〜0.050mass％の範囲では比ＳG／ＳM
を0.07〜0.30に制御し、それ以降は比ＳG／ＳMを0.05〜
0.10に制御することが、極低域までの脱りんを行うのに
有利である。In the above dephosphorization method, when the phosphorus concentration in the hot metal is in the range of 0.040 to 0.050 mass%, the ratio S G / S M
Was controlled to 0.07 to 0.30, after that 0.05 the ratio S G / S M
Controlling to 0.10 is advantageous for performing dephosphorization to an extremely low frequency range.
【００１１】ここで、転炉に装入した溶銑の表面積ＳM
とは、静止浴面における溶銑の上表面の面積である。そ
して溶銑の表面における酸素ガスの吹き付け面積ＳGと
は、幾何学的に決まるものであり、具体的には、前述の
溶銑表面積ＳMのうち、酸素ガスが吹きつけられる面積
である。Here, the surface area S M of the hot metal charged into the converter is
Is the area of the upper surface of the hot metal on the stationary bath surface. And The spraying area S G of the oxygen gas at the surface of the molten iron, which determined geometrically, specifically, of the hot metal surface area S M of the above, the area in which oxygen gas is blown.
【００１２】[0012]
【発明の実施の形態】さて、脱りん反応は酸化反応であ
るが、CaOが存在しなければ、その反応は進行しないた
め、従来は、吹錬初期にCaO源を一括投入して吹錬して
いた。また、脱りん処理後のりん濃度を0.040mass％以
下の低域あるいは極低域とするには、ホタル石などのス
ラグの融点を低下させるフラックスの添加が必要であっ
た。DESCRIPTION OF THE PREFERRED EMBODIMENTS The dephosphorization reaction is an oxidation reaction, but if CaO does not exist, the reaction does not proceed. I was Further, in order to reduce the phosphorus concentration after the dephosphorization treatment to a low range or an extremely low range of 0.040 mass% or less, it was necessary to add a flux that lowers the melting point of slag such as fluorite.
【００１３】そこで、発明者らは、脱りん反応が溶融ス
ラグとメタルとの間の反応であることから、スラグの溶
融割合（滓化率）に着目し、鋭意検討を重ねた。まず、
転炉吹錬において、酸素ガスが溶鋼や溶融スラグと衝突
する際の火点は高温であることが知られており、発明者
らは、この火点の面積を指標として、スラグの溶融率を
制御する手法について鋭意究明した。さらに、酸素ガス
流量についても併せて検討した。Therefore, the present inventors have paid much attention to the melting ratio of slag (slagging ratio) since the dephosphorization reaction is a reaction between molten slag and metal, and made intensive studies. First,
In converter blowing, it is known that the ignition point when oxygen gas collides with molten steel or molten slag is a high temperature, and the inventors use the area of this ignition point as an index to determine the melting rate of slag. We elaborate on the control method. Furthermore, the oxygen gas flow rate was also studied.
【００１４】すなわち、図1に示す転炉１を用いた溶銑
２の脱りん処理において、上吹きランス３から溶銑２の
表面に向けて酸素ガス４を供給する際、上記した定義に
従う吹き付け面積（火点面積）ＳGと溶銑の表面積ＳMと
の比ＳG／ＳMおよび、上吹きランス３から供給される酸
素の流量について、その条件を種々に変化して、りん濃
度が0.130〜0.140mass％の範囲の溶銑に脱りん処理を施
した。なお、溶銑に供給したのは、酸素ガスおよびフラ
ックス（CaO）、酸化鉄である。That is, in the dephosphorization treatment of the hot metal 2 using the converter 1 shown in FIG. 1, when the oxygen gas 4 is supplied from the upper blowing lance 3 toward the surface of the hot metal 2, the spray area ( Regarding the ratio S G / S M of the ignition point area S G to the surface area S M of the hot metal and the flow rate of oxygen supplied from the top blowing lance 3, the conditions are variously changed so that the phosphorus concentration is 0.130 to 0.140. Dephosphorization was applied to the hot metal in the mass% range. In addition, what was supplied to the hot metal was oxygen gas, flux (CaO), and iron oxide.
【００１５】上記の種々の条件で行った脱りん処理によ
って得られる溶銑のりん濃度を図２に示すように、まず
比ＳG／ＳMを0.05〜0.30の範囲に制御することによっ
て、脱りん処理によってりん濃度が0.040mass％以下の
低い領域まで脱りんを達成できることがわかる。但し、
比ＳG／ＳMを0.05〜0.30の範囲に制御した場合にあって
も、上吹きランス３からの酸素流量が0.5m3(標準状態)
／t・min未満および2.5m3(標準状態)／t・minをこえる
と、0.040mass％以下の低い領域までの脱りんは実現さ
れない。従って、比ＳG／ＳMを0.05〜0.30の範囲に、か
つ酸素流量を0.5〜2.5m3(標準状態)／t・minの範囲に、
それぞれ制御することが肝要であり、これらの条件下で
脱りん処理を行うことによって、ホタル石等の融点降下
剤を使用しなくても迅速にりん濃度0.040mass％以下の
低濃度域までの脱りんを達成できる。As shown in FIG. 2, the phosphorus concentration of the hot metal obtained by the dephosphorization treatment performed under the above various conditions is first controlled by controlling the ratio S G / S M in the range of 0.05 to 0.30 to remove the phosphorus. It can be seen that phosphorus removal can be achieved by the treatment up to a low phosphorus concentration of 0.040 mass% or less. However,
The ratio S G / S even when the M was controlled in the range of 0.05 to 0.30, the top-blown oxygen flow rate from the lance 3 is 0.5 m 3 (STP)
If it exceeds / t · min and exceeds 2.5 m 3 (standard state) / t · min, dephosphorization to a low region of 0.040 mass% or less cannot be realized. Therefore, the ratio S G / S M is in the range of 0.05 to 0.30 and the oxygen flow rate is in the range of 0.5 to 2.5 m 3 (standard state) / t · min.
It is important to control each of them, and by performing dephosphorization under these conditions, it is possible to quickly dephosphorize to a low concentration range of 0.040 mass% or less without using a melting point depressant such as fluorite. You can achieve phosphorus.
【００１６】ここで、上記比ＳG／ＳMが0.05より小さい
と、所望の脱りん率が得られないのは、火点面積が小さ
すぎて十分なスラグおよびメタル間の攪拌が得られず、
スラグの溶融率が低くなるためと考えられる。一方、比
ＳG／ＳMが0.30より大きいと、所望の脱りん率が得られ
ないのは、溶銑への酸素ガスの到達量が低くなるためで
あると考えられる。Here, if the ratio S G / S M is smaller than 0.05, the desired dephosphorization rate cannot be obtained because the fired area is too small to obtain sufficient slag and metal agitation. ,
It is considered that the melting rate of the slag becomes low. On the other hand, if the ratio S G / S M is larger than 0.30, it is considered that the reason why the desired dephosphorization rate cannot be obtained is that the amount of oxygen gas reaching the hot metal decreases.
【００１７】なお、火点面積ＳGに関して、複数の上吹
きランス３が複数のノズル孔を持つ場合、火点面積ＳG
はノズルジエットの重なりを考慮した値とする。具体的
には、各ノズル孔からのガスジェットの静止浴面での重
なりを幾何学的に求める。With respect to the fire area S G , if the plurality of upper blowing lances 3 have a plurality of nozzle holes, the fire area S G
Is a value taking into account the overlap of nozzle jets. Specifically, the overlap of the gas jet from each nozzle hole on the stationary bath surface is geometrically determined.
【００１８】また、酸素流量が0.5m3(標準状態)／t・mi
nより小さいと所望の脱りん率が得られないのは、酸素
量および攪拌が不足するためであり、一方2.5m3(標準状
態)／t・minをこえる場合は、酸素が過剰となり、スロ
ッピングが激しくなったりして、酸素効率が低下するた
めと考えられる。The oxygen flow rate is 0.5 m 3 (standard condition) / t · mi
If the value is smaller than n, the desired dephosphorization rate cannot be obtained because the amount of oxygen and stirring are insufficient.If the amount exceeds 2.5 m 3 (standard state) / t · min, the amount of oxygen becomes excessive and It is considered that the oxygen efficiency is lowered due to intense dropping.
【００１９】なお、図１は、底吹きランス５を介して転
炉底面からも酸素ガスあるいは不活性ガスを供給する、
上底吹転炉の例を示しているが、上吹転炉の形態であっ
てもかまわない。FIG. 1 shows that oxygen gas or inert gas is also supplied from the bottom of the converter via a bottom blowing lance 5.
Although an example of an upper-bottom converter is shown, the converter may be in the form of an upper converter.
【００２０】さらに、上記した条件下で脱りん処理を行
うに当り、溶銑中のりん濃度が0.040〜0.050mass％の範
囲では比ＳG／ＳMを0.07〜0.30に制御し、それ以降は比
ＳG／ＳMを0.05〜0.10に制御することが、極低域までの
脱りんを行うのに有利である。すなわち、上吹きランス
３からの酸素流量を1.7m3(標準状態)／t・minに調整し
て脱りん処理を行う際、溶銑中のりん濃度が0.040〜0.0
50mass％の前後において、比ＳG／ＳMを種々に変化させ
た場合の、脱りん処理後のりん濃度について調査した結
果を、図3に示す。なお、脱りん処理前の溶銑中りん濃
度は、全て0.130％〜0.140％である。Furthermore, contact to do dephosphorization treatment under the conditions described above, phosphorus concentration is controlled to 0.07 to .30 to the ratio S G / S M in the range of 0.040～0.050Mass% in the hot metal, thereafter ratio it is advantageous to carry out the dephosphorization to very low frequency for controlling the S G / S M to 0.05 to 0.10. That is, when performing the dephosphorization treatment by adjusting the oxygen flow rate from the upper blowing lance 3 to 1.7 m 3 (standard state) / t · min, the phosphorus concentration in the hot metal is 0.040 to 0.0
FIG. 3 shows the results of investigation on the phosphorus concentration after the dephosphorization treatment when the ratio S G / S M was variously changed around 50 mass%. The phosphorus concentrations in the hot metal before the dephosphorization treatment are all 0.130% to 0.140%.
【００２１】図３に示すように、脱りん処理前半の比Ｓ
G／ＳMを0.07〜0.30、処理後半の比ＳG／ＳMを0.05〜0.
10とすることによって、さらに脱りんが促進されること
が分かる。これは、処理後半にＳG／ＳMを若干小さくす
ることにより、浴面へのジェットの到達時の速度が大き
くなり、攪拌が大きくなるためである。As shown in FIG. 3, the ratio S in the first half of the dephosphorization treatment is
G / S M and 0.07 to 0.30, the ratio S G / S M in the second half of processing 0.05 to 0.
It can be seen that setting to 10 further promotes dephosphorization. This is because by slightly reducing S G / S M in the latter half of the process, the speed at which the jet reaches the bath surface is increased, and the agitation is increased.
【００２２】[0022]
【発明の効果】この発明によれば、ホタル石などの融点
降下剤を使用せずに、高効率で低域さらには極低域まで
の脱りん処理が実現されるから、低りん溶銑または極低
りん溶銑の溶製を環境への負荷を考慮して行う方途を拓
くことができる。According to the present invention, a high-efficiency dephosphorization treatment to a low region or even a very low region can be realized without using a melting point depressant such as fluorite or the like. It is possible to develop a method of producing low-phosphorus hot metal in consideration of the load on the environment.
【図１】 転炉を用いた脱りん処理の要領を示す図であ
る。FIG. 1 is a diagram showing a procedure of a dephosphorization process using a converter.
【図２】 脱りん処理における比ＳG／ＳMと処理後の溶
銑りん濃度との関係を示す図である。FIG. 2 is a diagram showing the relationship between the ratio S G / S M in the dephosphorization treatment and the concentration of hot metal phosphorus after the treatment.
【図３】 脱りん処理の前半および後半で比ＳG／ＳMを
変化した場合の処理パターンと処理後の溶銑りん濃度と
の関係を示す図である。FIG. 3 is a diagram showing a relationship between a treatment pattern when the ratio S G / S M is changed in the first half and the latter half of the dephosphorization treatment and the hot metal phosphorus concentration after the treatment.
１ 転炉 ２ 溶銑 ３ 上吹きランス ４ 酸素ガス ５ 底吹きランス DESCRIPTION OF SYMBOLS 1 Converter 2 Hot metal 3 Top blowing lance 4 Oxygen gas 5 Bottom blowing lance
───────────────────────────────────────────────────── フロントページの続き (72)発明者 橋本 雅之 岡山県倉敷市水島川崎通１丁目（番地な し） 川崎製鉄株式会社水島製鉄所内 (72)発明者 朝比奈 健 岡山県倉敷市水島川崎通１丁目（番地な し） 川崎製鉄株式会社水島製鉄所内 Ｆターム(参考） 4K014 AA02 AC13 AC16 AC17 BB01 4K070 AB06 BA05 BA07 BB02 BD13 EA09 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masayuki Hashimoto 1-chome, Mizushima-Kawasaki-dori, Kurashiki-shi, Okayama Pref. Chome (without address) Kawasaki Steel Corporation Mizushima Works F-term (reference) 4K014 AA02 AC13 AC16 AC17 BB01 4K070 AB06 BA05 BA07 BB02 BD13 EA09
Claims (2)
するとともに、酸素ガスを上吹きして溶銑の予備処理を
行うに当り、転炉に装入した溶銑の表面積ＳMと、該溶
銑の表面における酸素ガスの吹き付け面積ＳGとの比ＳG
／ＳMを0.05〜0.30、かつ酸素ガス流量を0.5〜2.5m
3（標準状態）／t・minに制御して、溶銑中のりん濃度
を0.040mass％以下に調整することを特徴とする転炉を
用いた溶銑の脱りん方法。1. A supplies the flux to the molten iron was charged into a converter, hits the preliminary treatment of molten pig iron by blowing on oxygen gas, and the surface area S M of the molten iron was charged into a converter, solution pig iron Ratio S G to the oxygen gas spray area S G on the surface of the steel
/ A S M 0.05 to 0.30, and 0.5~2.5m the oxygen gas flow rate
3. A method for dephosphorizing hot metal using a converter, wherein the phosphorus concentration in the hot metal is adjusted to 0.040 mass% or less by controlling to 3 (standard state) / t · min.
の範囲では比ＳG／ＳMを0.07〜0.30に制御し、それ以降
は比ＳG／ＳMを0.05〜0.10に制御することを特徴とする
請求項1記載の転炉を用いた溶銑の脱りん方法。2. The phosphorus concentration in the hot metal is 0.040 to 0.050 mass%.
Of controlling the ratio S G / S M to 0.07 to 0.30 range, the molten iron using a converter according to claim 1, wherein the thereafter controlling the ratio S G / S M to 0.05 to 0.10 Dephosphorization method.
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|---|---|
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| JP3861618B2 JP3861618B2 (en) | 2006-12-20 |
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