JPH0813016A - Method for dephosphorizing and desulfurizing molten iron - Google Patents
Method for dephosphorizing and desulfurizing molten ironInfo
- Publication number
- JPH0813016A JPH0813016A JP15088894A JP15088894A JPH0813016A JP H0813016 A JPH0813016 A JP H0813016A JP 15088894 A JP15088894 A JP 15088894A JP 15088894 A JP15088894 A JP 15088894A JP H0813016 A JPH0813016 A JP H0813016A
- Authority
- JP
- Japan
- Prior art keywords
- oxygen
- dephosphorization
- desulfurization
- blowing
- hot metal
- 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.)
- Granted
Links
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- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】この発明は、転炉内での溶銑処理
方法に関し、処理溶銑の温度低下のない好適な脱燐・脱
硫法を提案するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot metal treatment method in a converter, and proposes a suitable dephosphorization / desulfurization method in which the temperature of the hot metal is not lowered.
【０００２】[0002]
【従来の技術】一般に、溶銑の脱燐・脱硫は、転炉精錬
の付加を軽減し、少ない副原料によって所望の成分組成
になる鋼を得るために行うことは周知の事実である。そ
の実施形態としては、トピード車内の溶銑に対し耐火物
で保護した鋼製パイプを介して精錬剤を吹き込む、いわ
ゆる「トピードインジェクション法」、トピード車のか
わりに溶銑搬送鍋を用いる「溶銑鍋インジェクション
法」、高炉鋳床の樋内にて連続的に精錬剤を吹き込んだ
り、吹き付けたりする「鋳床脱燐、鋳床脱硫法」などが
ある。一方、精錬容器として転炉を用いる方法も知られ
ている。この発明の対象となる転炉を用いる技術につい
ては、例えば特公昭61−40005号公報（溶銑処理方法）
には、底吹き転炉の炉底羽口より純酸素により生石灰や
ホタル石などを含む複合脱燐剤を吹き込む手段が開示さ
れている。2. Description of the Related Art Generally, it is a well-known fact that hot metal dephosphorization / desulfurization is carried out in order to reduce the addition of converter refining and obtain a steel having a desired composition with a small amount of auxiliary raw materials. As its embodiment, the refining agent is blown through the steel pipe protected by the refractory against the hot metal in the toypeed car, the so-called "topeed injection method", "hot metal ladle injection using a hot metal carrier ladle instead of the toypeed car. Method "and" casting bed dephosphorization, casting bed desulfurization method "in which the refining agent is continuously blown or sprayed in the gutter of the blast furnace casting floor. On the other hand, a method using a converter as a refining vessel is also known. Regarding the technique of using the converter which is the subject of the present invention, for example, Japanese Patent Publication No. 40005/1986 (hot metal treatment method)
Discloses a means for injecting a complex dephosphorizing agent containing quicklime, fluorspar, etc. with pure oxygen from the bottom tuyere of a bottom blowing converter.
【０００３】また、特公昭62−3203号公報（溶銑の脱Ｐ
・脱Ｓ精錬方法）には、反応容器は限定していないもの
の、あらかじめ脱Siを行った溶銑に対して、精錬前半は
生石灰を主体とした複合フラックスを気体酸素とともに
吹き込んで脱Ｐを行い、精錬後半には生石灰を主体とし
た複合フラックスを不活性カズとともに吹き込んで脱Ｓ
を行う手段が示されている。しかしながら、上記特公昭
61−40005 号公報の手段では、１種類の精錬剤（脱燐
剤）を底吹き羽口より大量の純酸素で吹き込むという簡
単な方法で容易に高い脱燐率を得ることがてきるが、脱
硫率については高々50％であり、近年の低Ｓ鋼のように
Ｓ含有量の上限値の厳しい要求には適用できないという
問題があり、したがって、この溶銑脱燐処理の前工程と
して、何らかの溶銑脱硫処理が必要であった。さらに、
特公昭62−3203号公報の手段では、事前に脱Si処理を施
し、〔Si〕≦0.1 ％とした溶銑についてのみ脱Ｐ・脱Ｓ
の逐次精錬を行い、Ｐ含有量＜0.010％、Ｓ含有量＜0.0
05 ％の低Ｐ、低Ｓ溶銑を得るもので、この溶銑の脱Ｐ
・脱Ｓ精錬には、何らかの事前の溶銑脱Si処理が必要で
あった。すなわち、上記の二手段は事前の溶銑予備処理
を前提とした脱Ｐ・脱Ｓ処理方法であった。Further, Japanese Examined Patent Publication No. 62-3203 (De-P of hot metal)
In the de-S-refining method), the reaction vessel is not limited, but in the first half of the refining, a complex flux mainly containing quick lime is blown together with gaseous oxygen to de-P the hot metal that has been subjected to the de-Si. In the latter half of refining, a complex flux composed mainly of quick lime is blown together with inert kazu to remove S.
The means for doing is shown. However, the above Japanese Patent Publication
According to the method of 61-40005, a high dephosphorization rate can be easily obtained by a simple method of blowing one kind of refining agent (dephosphorizing agent) with a large amount of pure oxygen from the bottom-blown tuyere. The desulfurization rate is 50% at most, and there is a problem that it cannot be applied to the strict requirement of the upper limit of S content such as low S steel in recent years. Therefore, as a pre-process of this hot metal dephosphorization treatment, some kind of hot metal is required. Desulfurization treatment was required. further,
According to the means of Japanese Patent Publication No. 62-3203, de-Ping and de-S-degradation are performed only on hot metal with [Si] ≤ 0.1% which has been subjected to de-Si treatment in advance.
Sequential refining of P content <0.010%, S content <0.0
05% low P and low S hot metal is obtained.
-Some kind of prior hot metal removal Si treatment was required for S-refining. That is, the above-described two means were the de-P / de-S treatment method based on the pre-treatment of the hot metal pretreatment.
【０００４】一方、これまでの溶銑処理で十分な脱燐・
脱硫処理をしようとすると溶銑温度の低下が生じ、この
溶銑温度の低下は、現在リサイクルが大きな問題となっ
ているスクラップの製鋼過程での使用量が減少する、あ
るいは安価な鉄源である鉄鉱石、Ｍｎ源であるＭｎ鉱石
の使用量が減少する等の問題点があり、これらの問題を
解決しようとすれば、脱炭炉において高価な低Ｓ濃度の
加炭剤あるいは合金鉄を熱源として昇温を行う必要があ
った。On the other hand, sufficient dephosphorization by the conventional hot metal treatment
When desulfurization treatment is attempted, the hot metal temperature lowers, and this lowering of the hot metal temperature reduces the amount of scrap used in the steelmaking process, which is currently a major problem for recycling, or iron ore, which is an inexpensive iron source. However, there is a problem that the amount of Mn ore, which is a Mn source, is reduced. To solve these problems, an expensive low S concentration carburizing agent or ferroalloy is used as a heat source in a decarburization furnace. It was necessary to warm up.
【０００５】[0005]
【発明が解決しようとする課題】この発明は、前記した
問題点を有利に解決しようとするもので、特に上底吹き
転炉を用い、事前の溶銑の脱硫処理や脱珪処理などを施
さなくても、高効率の脱燐・脱硫（Ｐ＜ 0.010％、Ｓ＜
0.005％目標）が達成でき、かつ、溶銑温度の低下が防
止できる溶銑の脱燐・脱硫法を提案することを目的とす
る。DISCLOSURE OF THE INVENTION The present invention is intended to solve the above-mentioned problems in an advantageous manner. In particular, an upper-bottom blowing converter is used, and prior desulfurization treatment or desiliconization treatment of hot metal is not performed. However, highly efficient dephosphorization / desulfurization (P <0.010%, S <
The purpose is to propose a hot metal dephosphorization / desulfurization method that can achieve the target of 0.005%) and prevent the decrease of the hot metal temperature.
【０００６】[0006]
【課題を解決するための手段】この発明の要旨は以下の
通りである。転炉を用いて、溶銑浴面下に設ける羽口か
ら精錬剤を溶銑中に吹き込み脱燐及び脱硫を行う溶銑処
理方法において、上底吹き転炉を用い、底吹きにより酸
素あるいは酸素とその他のガスの混合ガスによって生石
灰系フラックスを吹き込む脱燐処理と、それに引き続い
て非酸化性ガスを用いて生石灰系フラックスを吹き込む
脱硫処理とを酸素の上吹きを付加して行い、かつ、上記
脱燐期の底吹き酸素吹き込み速度を0.2 Nm3/min ・ｔ以
上とし、上吹き酸素原単位（Nm3/t)と底吹き酸素原単位
（Ｎm3／ｔ）との比を３：７から１：９の範囲に調整す
ることを特徴とする溶銑の脱燐・脱硫法であり、上記に
おいて酸素の上吹きを脱燐期のみとするものであり、さ
らに、それらの脱燐処理後のスラグのCaO （wt％）／Si
O2（wt％）であらわす塩基度を2.0 以上とするものであ
る。The summary of the present invention is as follows. In a hot metal treatment method in which a refining agent is blown into hot metal from a tuyere provided below the hot metal bath surface using a converter to perform dephosphorization and desulfurization, a top-bottom blowing converter is used to blow oxygen or oxygen and other oxygen by bottom blowing. A dephosphorization treatment in which quicklime-based flux is blown by a mixed gas of gases, and a desulfurization treatment in which quicklime-based flux is subsequently blown in using a non-oxidizing gas are performed by adding oxygen top blowing, and The bottom-blown oxygen blowing rate is 0.2 Nm 3 / min · t or more, and the ratio of the top-blown oxygen basic unit (Nm 3 / t) to the bottom-blown oxygen basic unit (Nm 3 / t) is 3: 7 to 1: It is a dephosphorization / desulfurization method of hot metal characterized by adjusting to a range of 9, and in the above, the upper blowing of oxygen is performed only in the dephosphorization period, and further, CaO of the slag after the dephosphorization treatment. (Wt%) / Si
The basicity expressed by O 2 (wt%) is 2.0 or more.
【０００７】[0007]
【作用】この発明の作用効果を実験・検討結果をもとに
以下に述べる。発明者らは、上底吹き転炉型精錬容器
（上底吹き転炉等）を用いて脱燐・脱硫反応を広範囲に
わたって実験・検討を行った。それらの実験例及び得ら
れた知見などを以下に列記する。 上底吹き転炉型精錬容器を用いて溶銑の脱燐・脱硫
処理を行うに際しては、酸化反応である脱燐と還元反応
である脱硫とは時間的に分離して行うほうが、脱燐・脱
硫の反応効率を総合してみた場合、有利である。 また、その場合、脱燐処理を先に行い、ついで脱硫
処理を行う方が、脱硫期で生起するスラグの復流を最小
限に抑えることができるため有利である。 上底吹き転炉型精錬容器を用いて溶銑の脱燐・脱硫
処理を行った場合、該精錬容器のフリーボードが長いこ
とから、従来不可能であった底吹き酸素ガスの大量供給
が可能となり、その結果、特に事前に脱珪処理を行って
いない溶銑を用いても高効率の脱燐ができる。また、そ
の際酸素の上吹きは溶銑温度の低下防止に顕著な効果を
発揮する。 底吹き酸素の大量供給により、図１に示すような以
下に列記する反応が進み高効率の脱燐が達成されること
が明らかとなった。The function and effect of the present invention will be described below based on the results of experiments and examinations. The inventors conducted extensive experiments and studies on the dephosphorization / desulfurization reaction using a top-bottom blow converter type refining vessel (top-bottom blow converter, etc.). The experimental examples and the obtained findings are listed below. When performing dephosphorization / desulfurization of hot metal using an upper / bottom blow converter type refining vessel, it is better to separate the dephosphorization, which is an oxidation reaction, from the desulfurization, which is a reduction reaction, in time. This is advantageous when the reaction efficiencies of are combined. Further, in that case, it is advantageous to perform the dephosphorization treatment first, and then to perform the desulfurization treatment, since the reflow of the slag that occurs during the desulfurization period can be minimized. When performing dephosphorization / desulfurization treatment of hot metal using a top-bottomed converter type refining vessel, the freeboard of the refining vessel is long, making it possible to supply a large amount of bottom-blown oxygen gas, which was not possible in the past. As a result, high-efficiency dephosphorization can be achieved even with hot metal that has not been previously desiliconized. Further, at this time, the top blowing of oxygen exerts a remarkable effect in preventing the lowering of the hot metal temperature. It was revealed that a large amount of bottom-blown oxygen was supplied and the following reactions shown in FIG. 1 proceeded to achieve highly efficient dephosphorization.
【０００８】ここに図１は、底吹き酸素の大量吹き込み
における溶銑の脱燐メカニズムを示す説明図である。 （ａ）酸素と共に底吹きされたCaO 粉は底吹き羽口直上
の火点近傍に大量に形成される酸化鉄と反応してCaO −
フェライト粒となる。 （ｂ）この粒は液相分率が高いので球形となりスラグ粒
の原形となる。 （ｃ）このスラグ粒は溶銑中の浮上過程で下記する
（１）式により〔Ｐ〕を酸化し、３CaO ・P2O5に近い組
成のスラグ粒になる。FIG. 1 is an explanatory view showing the dephosphorization mechanism of hot metal when a large amount of bottom-blown oxygen is blown. (A) CaO powder bottom-blown with oxygen reacts with iron oxide formed in large quantity near the fire point just above the bottom-blown tuyere, and CaO −
Becomes ferrite grains. (B) Since these particles have a high liquid phase fraction, they become spherical and become the original form of slag particles. (C) The slag particles oxidizes (P) by which the following with floating process of the hot metal (1), the slag grains having a composition close to 3CaO · P 2 O 5.
【数１】 ２〔Ｐ〕＋5/3 (Fe2O3) → (P2O5) ＋10/3 Fe …(1) （ｄ）ただし、〔％Si〕≧0.020 の吹錬期間には、脱燐
反応生成物中にSiO2が含まれ、その含有量が増すと（％
P2O5)は減少する。すなわち、脱燐効率が低下する。 （ｅ）しかしながら、〔％Si〕≧0.020 の場合において
も、底吹きする酸素吹き込み量を増せば、脱燐反応生成
物中に含まれるSiO2も相対的に増加蓄積されることがな
くなり、（％P2O5) は減少しない。すなわち、脱燐効率
を高いまま維持できる。 （ｆ）このようにして生成された３CaO ・P2O5は、トッ
プスラグの巻き込みや、脱珪時に生成し浮上しきれずに
溶銑中に懸濁しているCaO/SiO2比率の小さいCaO ・SiO2
スラグ粒と合体してSiO2の含有比率が多い脱燐スラグと
なる。 （ｇ）このようなメカニズムで進行する脱燐反応による
脱燐は、全脱燐の50〜70％に達する。[Equation 1] 2 [P] +5/3 (Fe 2 O 3 ) → (P 2 O 5 ) +10/3 Fe (1) (d) However, in the blowing period of [% Si] ≧ 0.020, If the dephosphorization reaction product contains SiO 2 and its content increases (%
P 2 O 5 ) decreases. That is, the dephosphorization efficiency decreases. (E) However, even in the case of [% Si] ≧ 0.020, if the amount of oxygen blown at the bottom is increased, the SiO 2 contained in the dephosphorization reaction product is also prevented from being relatively increased and accumulated. % P 2 O 5 ) does not decrease. That is, the dephosphorization efficiency can be maintained high. (F) Thus 3CaO · P 2 O 5 generated in the inclusion of top slag and less CaO · SiO of CaO / SiO 2 ratio are suspended in molten iron without being completely floated generated de珪時2
Combined with slag particles, it becomes dephosphorized slag with a high SiO 2 content ratio. (G) Dephosphorization by the dephosphorization reaction which proceeds by such a mechanism reaches 50 to 70% of the total dephosphorization.
【０００９】 上底吹き転炉を用いて、底吹きにより
酸素を搬送ガスとして脱燐フラックスを吹き込む脱燐処
理と、それに続いて非酸化性ガスを搬送ガスとする脱硫
フラックスを吹き込む脱硫処理との溶銑処理を行い、底
吹き酸素吹き込み速度と脱硫率との関係について調査し
た。なお上記において処理前溶銑の〔Si〕、酸素ガス原
単位及びフラックス原単位は一定とした。これらの調査
結果を図２にまとめて示す。図２は底吹き酸素吹き込み
速度と脱硫率との関係を示すグラフである。[0009] Using a top-bottom blowing converter, a desulfurization treatment in which oxygen is used as a carrier gas and a dephosphorization flux is blown by bottom blowing, followed by a desulfurization treatment in which a desulfurization flux using a non-oxidizing gas as a carrier gas is blown. After the hot metal treatment, the relationship between the bottom blowing oxygen blowing rate and the desulfurization rate was investigated. In the above, the [Si] of the hot metal before treatment, the oxygen gas basic unit and the flux basic unit were constant. The results of these investigations are summarized in Figure 2. FIG. 2 is a graph showing the relationship between the bottom-blown oxygen blowing rate and the desulfurization rate.
【００１０】図２によれば、処理前溶銑の〔％Si〕が一
定の条件のもとでは、底吹き酸素の吹き込み速度が増加
するにつれて脱硫率は増加するが、吹き込み速度が0.2
Ｎm3／min ・ｔ以上では脱硫率はほぼ一定になる。According to FIG. 2, under the condition that the [% Si] of the hot metal before treatment is constant, the desulfurization rate increases as the blowing rate of the bottom-blown oxygen increases, but the blowing rate is 0.2.
At Nm 3 / min · t or higher, the desulfurization rate becomes almost constant.
【００１１】これは、底吹き酸素吹き込み速度が、0.2
Ｎm3／min ・ｔまでは、トップスラグの（Ｔ．Fe）が底
吹き酸素による攪拌によって溶銑による還元が進行し、
その結果脱硫に有利な条件になるのに対し、0.2 Ｎm3／
min ・ｔ以上になると、トップスラグの（Ｔ．Fe）は十
分低い状態に保たれてはいるもののそれ以上の脱硫効果
が得られないことを示している。なお、より高水準の脱
硫効果を得るためには他の要因によらなければならない
ものと考えられる。The bottom blowing oxygen blowing rate is 0.2
Up to Nm 3 /min.t, the top slag (T.Fe) is reduced by the hot metal by stirring with bottom-blown oxygen,
As a result, the conditions are favorable for desulfurization, while 0.2 Nm 3 /
When min.t is exceeded, the top slag (T.Fe) is kept at a sufficiently low level, but it is shown that no further desulfurization effect can be obtained. It is considered that other factors must be used to obtain a higher level of desulfurization effect.
【００１２】 上底吹き転炉を用いて、底吹き酸素吹
き込み速度を0.2 Ｎm3／min ・ｔ以上とし、上吹き酸素
を含む全酸素原単位、フラックス原単位、処理前溶銑の
〔Si〕量が一定の条件で、上吹き酸素と底吹き酸素の原
単位の比を変えて脱燐処理（同時に脱硫もする）を行
い、脱燐量、同時脱硫率及び処理溶銑の温度低下量など
を調査した。これらの調査結果を図３にまとめて示す。
図３は上吹きと底吹きとの酸素原単位の比と脱燐量、同
時脱硫率及び溶銑の温度低下量との関係を示すグラフで
ある。Using a top-bottom blow converter, the bottom-blown oxygen blowing rate was set to 0.2 Nm 3 / min · t or more, and the total oxygen basic unit including the top-blown oxygen, the flux basic unit, the [Si] amount of the hot metal before treatment Under a certain condition, the ratio of the basic unit of top-blown oxygen and bottom-blown oxygen is changed to perform dephosphorization treatment (also desulfurization is performed at the same time), and the amount of dephosphorization, the simultaneous desulfurization rate, and the temperature decrease of the hot metal to be treated are investigated did. The results of these investigations are summarized in FIG.
FIG. 3 is a graph showing the relationship between the ratio of oxygen basic units of top-blowing and bottom-blowing, the amount of dephosphorization, the simultaneous desulfurization rate, and the amount of temperature decrease of hot metal.
【００１３】図３によれば、全酸素原単位に占める上吹
き酸素原単位の比率を増加して行くと、上吹きと底吹き
との酸素原単位の比が３：７になるまでは脱燐量は一定
であるが、その後上吹き酸素原単位の比率が増加するに
したがって、脱燐量は低下する。この脱燐量の低下は上
吹き酸素原単位を増加させると底吹き酸素原単位は減少
することになり、かつ上吹き酸素が浴面に到達しないで
系外に排出されるものがあるため、脱燐に有効な酸素量
が減少するためと考えられる。According to FIG. 3, when the ratio of the upper blown oxygen unit to the total oxygen unit is increased, the oxygen is removed until the ratio of the upper blown and the bottom blown oxygen unit becomes 3: 7. The phosphorus content is constant, but thereafter, the dephosphorization content decreases as the ratio of the upper-blown oxygen basic unit increases. This decrease in the amount of dephosphorization means that if the top blown oxygen unit is increased, the bottom blown oxygen unit is reduced, and because there is some top blown oxygen that is discharged outside the system without reaching the bath surface, It is considered that the amount of oxygen effective for dephosphorization decreases.
【００１４】また、同時脱硫率も上吹きと底吹きとの酸
素原単位の比が３：７を境に上吹き酸素が増加するにし
たがって低下する。これは底吹きの酸素原単位（吹き込
み速度）が小さくなったことによって攪拌力が弱くなっ
たこと、さらには、上吹き酸素の原単位が増加したこと
によってトップスラグ中の（％Fe＋Ｏ）が増加したため
と考えられる。Further, the simultaneous desulfurization rate also decreases as the amount of top-blown oxygen increases when the oxygen unit ratio of top-blown and bottom-blown is 3: 7. This is because the stirring force was weakened due to the decrease in the oxygen unit consumption (blowing speed) of bottom blowing, and further, the increase of (% Fe + O) in the top slag due to the increase of the basic unit of top blowing oxygen. It is thought that it was done.
【００１５】さらに、上吹きの酸素原単位を増加させて
行くと、溶銑の温度低下量は少なくなり、上吹きと底吹
きとの酸素原単位の比が１：９になると溶銑の温度低下
量は僅かになる。これは上吹き酸素の２次燃焼による温
度補償が溶銑の温度低下防止に有効であることを示して
いる。したがって、溶銑の温度低下を防止するために
は、上吹きと底吹きとの酸素原単位の比が１：９より上
吹き酸素原単位を多くすることが重要である。Further, when the oxygen basic unit for top blowing is increased, the temperature decrease amount of the hot metal decreases, and when the ratio of the oxygen basic unit for top blowing and bottom blowing is 1: 9, the temperature decrease amount of the hot metal is reduced. Becomes a little. This shows that temperature compensation by secondary combustion of top-blown oxygen is effective in preventing the temperature drop of the hot metal. Therefore, in order to prevent the temperature drop of the hot metal, it is important that the ratio of the oxygen basic unit of top blowing to the bottom blowing is more than 1: 9.
【００１６】 さらに、５ｔ規模の上底吹き転炉を用
いて実験を行い以下に列記する知見を得た。 ａ．上吹きと底吹きとの酸素原単位の比を２：８、底吹
き酸素吹き込み速度（脱燐期）を0.2 Ｎm3／min ・ｔ以
上とし、かつ、脱燐及び脱硫フラック原単位一定の条件
にて脱燐・脱硫を行い、上吹き酸素原単位の（脱硫期）
／（脱燐期＋脱硫期）の値と、脱硫率及び溶銑の温度低
下量との関係について調査した。上吹き酸素原単位の
（脱硫期）／（脱燐期＋脱硫期）の値と、脱硫率との関
係を図４に、溶銑の温度低下量との関係を図５に示す。Further, an experiment was conducted using a 5t scale top-bottom blowing converter, and the following findings were obtained. a. Conditions where the ratio of top and bottom blowing oxygen unit is 2: 8, the bottom blowing oxygen blowing rate (dephosphorization period) is 0.2 Nm 3 / min · t or more, and the dephosphorization and desulfurization flax unit is constant. Desulfurization and desulfurization at
The relationship between the value of / (desulfurization period + desulfurization period) and the desulfurization rate and the amount of temperature decrease of the hot metal was investigated. FIG. 4 shows the relationship between the (desulfurization period) / (desulfurization period + desulfurization period) value of the upper blown oxygen unit and the desulfurization rate, and FIG. 5 shows the relationship with the amount of temperature decrease of the hot metal.
【００１７】図４より脱硫期の上吹き酸素が増加すると
脱硫率は低下することが分る。これは脱硫期に酸素の上
吹きを行うことにより、トップスラグ中の（Ｔ．Fe）が
増加し、これにより脱硫効果が阻害されるためと考えら
れる。また、図５より上吹き酸素による溶銑の温度補償
の効果は脱硫期における上吹き酸素原単位に関係なく一
定であることが分かる。It can be seen from FIG. 4 that the desulfurization rate decreases as the amount of oxygen blown upward in the desulfurization period increases. This is considered to be because (T.Fe) in the top slag increases due to the upward blowing of oxygen during the desulfurization period, which impedes the desulfurization effect. Further, it can be seen from FIG. 5 that the effect of temperature compensation of hot metal by top-blown oxygen is constant regardless of the top-blown oxygen unit during the desulfurization period.
【００１８】これらの結果より、酸素の上吹きを脱燐期
のみに集中して行うことによって溶銑温度を低下させる
ことなく脱硫率を向上させることができることになる。From these results, it is possible to improve the desulfurization rate without lowering the hot metal temperature by performing the upward blowing of oxygen only in the dephosphorization period.
【００１９】ｂ．脱硫フラックス原単位一定の条件に
て、上吹きと底吹きとの酸素原単位の比を２：８、底吹
き酸素吹き込み速度を0.2 Ｎm3／min ・ｔとし、脱硫期
には上吹きの酸素を吹き込むことなく脱燐・脱硫処理を
行い、脱燐処理後のスラグの塩基度（CaO ／SiO2）と脱
硫率との関係を調査した。脱燐後のスラグの塩基度とそ
の後の脱硫処理における脱硫率との関係を図６に示す。B. Desulfurization flux basic unit: Under a constant condition, the ratio of oxygen basic units of top blowing and bottom blowing is 2: 8, and the bottom blowing oxygen blowing rate is 0.2 Nm 3 / min · t. Desulfurization / desulfurization treatment was performed without blowing in, and the relationship between the basicity (CaO / SiO 2 ) of the slag after the dephosphorization treatment and the desulfurization rate was investigated. FIG. 6 shows the relationship between the basicity of the slag after dephosphorization and the desulfurization rate in the subsequent desulfurization treatment.
【００２０】図６より、脱燐処理後のスラグの塩基度が
2.0 未満では、塩基度の上昇とともに脱硫処理後の脱硫
率も増大するが、2.0 以上では脱硫率はほとんど変りな
い。これは、塩基度が2.0 未満の領域では、塩基度の上
昇とともにそのスラグと平衡するための溶銑〔％Si〕の
低減効果が働き、塩基度2.0 以上では、スラグと平衡す
るための溶銑〔％Si〕の低減効果とスラグの融点の上昇
による脱硫速度低下の効果がほぼつりあったためと考え
られる。From FIG. 6, the basicity of the slag after the dephosphorization treatment is
When it is less than 2.0, the desulfurization rate after desulfurization increases as the basicity increases, but when it is 2.0 or more, the desulfurization rate hardly changes. This is because when the basicity is less than 2.0, the effect of reducing the hot metal [% Si] to equilibrate with the slag works as the basicity rises, and when the basicity is 2.0 or more, the hot metal [% Si] to equilibrate with the slag becomes effective. It is considered that the effect of reducing [Si] and the effect of decreasing the desulfurization rate by increasing the melting point of slag were almost balanced.
【００２１】これらの結果より、脱燐処理後のスラグの
塩基度を2.0 以上とすることによって、その後の脱硫処
理における脱硫率をより向上させることができる。From these results, by setting the basicity of the slag after the dephosphorization treatment to 2.0 or more, the desulfurization rate in the subsequent desulfurization treatment can be further improved.
【００２２】以上、これらの実験・検討結果より、上底
吹き転炉を用いて脱燐処理（同時に脱硫もする）を行う
に際しては、底吹き酸素吹き込み速度が0.2 Ｎm3／min
・ｔ以上の強攪拌を行うことにより、溶銑の〔Si〕濃度
が高くても脱燐率を高水準に維持できること、またその
場合上吹きと底吹きとの酸素原単位の比を３：７から
１：９の範囲にすることが最適でありかくすることによ
り脱燐・脱硫処理溶銑の温度低下を防止できることが明
らかとなった。As described above, from the results of these experiments and examinations, when performing the dephosphorization treatment (simultaneously with desulfurization) using the top-bottom blowing converter, the bottom-blowing oxygen blowing rate was 0.2 Nm 3 / min.
-By performing strong stirring for at least t, the dephosphorization rate can be maintained at a high level even if the [Si] concentration of the hot metal is high, and in that case, the ratio of the oxygen basic unit of top blowing to bottom blowing is 3: 7. Therefore, it was found that the optimum range is 1: 9, and it is clear that the temperature reduction of the dephosphorization / desulfurization hot metal can be prevented by doing so.
【００２３】さらに、脱燐期のみ上吹き酸素を吹き込む
ことで、溶銑温度を低下させることなくその後の脱硫処
理での脱硫率の向上がはかれること、脱燐処理後のスラ
グの塩基度を2.0 以上とすることによって、その後の脱
硫処理での脱硫率をより向上できることなども判明し
た。Furthermore, by blowing up blown oxygen only during the dephosphorization period, the desulfurization rate can be improved in the subsequent desulfurization treatment without lowering the hot metal temperature, and the basicity of the slag after the dephosphorization treatment is 2.0 or more. It has also been found that the above-mentioned can further improve the desulfurization rate in the subsequent desulfurization treatment.
【００２４】[0024]
適合例１ 250 ｔ上底吹き転炉を用いて、溶銑250 ｔの脱燐・脱硫
処理を行い、脱燐・脱硫処理前後の溶銑の成分組成及び
温度、さらには脱燐処理後のトップスラグの組成などに
ついて調査した。Conformance Example 1 Using a 250 ton top-and-bottom blowing converter, 250 ton of hot metal is subjected to dephosphorization / desulfurization treatment, the composition and temperature of the hot metal before and after dephosphorization / desulfurization treatment, and the top slag The composition was investigated.
【００２５】脱燐・脱硫処理条件としては、まず、底吹
きにより、脱燐用フラックスを純酸素を搬送ガスとして
吹き込む脱燐処理を10分間行ったのち、つづいて脱硫用
フラックスを窒素を搬送ガスとして吹き込む脱硫処理を
３分間行い、上吹きにより、上記脱燐期及び脱硫期を通
して合計４分間純酸素を吹き込んだ。As the dephosphorization / desulfurization treatment conditions, first, a dephosphorization treatment is carried out by blowing the bottom surface with the dephosphorization flux as pure oxygen as a carrier gas, and then the desulfurization flux is supplied with nitrogen as a carrier gas. Desulfurization treatment is performed for 3 minutes, and pure oxygen is blown for a total of 4 minutes through the above-described dephosphorization period and desulfurization period.
【００２６】また、上記において、脱燐処理中は、底吹
き酸素吹き込み速度を0.64Ｎm3／min ・ｔ、フラックス
吹き込み速度を1.2 kg／min ・ｔ、脱硫処理中は、窒素
吹き込み速度を0.64Ｎm3／min ・ｔ、フラックス吹き込
み速度を1.2 kg／min ・ｔとし、さらに上吹き酸素吹き
込み速度は0.4 Ｎm3／min ・ｔとした。ここで、上吹き
と底吹きとの酸素原単位の比は２：８となる。なお、脱
燐及び脱硫用フラックスは共に、生石灰粉とホタル石粉
とを８：２の割合で混合したものを用いた。In the above, during the dephosphorization treatment, the bottom blowing oxygen blowing rate was 0.64 Nm 3 /min.t, the flux blowing rate was 1.2 kg / min.t, and the nitrogen blowing rate was 0.64 Nm during the desulfurization treatment. 3 / min · t, the flux blowing rate was 1.2 kg / min · t, and the top blowing oxygen blowing rate was 0.4 Nm 3 / min · t. Here, the ratio of the oxygen basic unit between top blowing and bottom blowing is 2: 8. For the dephosphorization and desulfurization flux, a mixture of quicklime powder and fluorspar powder at a ratio of 8: 2 was used.
【００２７】表１に脱燐・脱硫処理前後の溶銑の成分組
成及び温度、表２に脱燐処理後のスラグの成分組成を示
す。Table 1 shows the composition and temperature of the hot metal before and after the dephosphorization / desulfurization treatment, and Table 2 shows the composition of the slag after the dephosphorization treatment.
【００２８】[0028]
【表１】 [Table 1]
【００２９】[0029]
【表２】 [Table 2]
【００３０】適合例２ 上吹き酸素の吹き込みを脱燐期のみとして４分間行った
以外は適合例１と同様の脱燐・脱硫処理を施し、処理前
後の溶銑の成分組成及び温度を調査した。表３に脱燐・
脱硫処理前後の溶銑の成分組成及び温度を示す。Adaptation Example 2 The same dephosphorization / desulfurization treatment as in Adaptation Example 1 was carried out except that the blowing of top-blown oxygen was performed only for the dephosphorization period for 4 minutes, and the composition and temperature of the hot metal before and after the treatment were investigated. Dephosphorization in Table 3
The component composition and temperature of the hot metal before and after desulfurization treatment are shown.
【００３１】[0031]
【表３】 [Table 3]
【００３２】適合例３ 〔Si〕濃度が0.3 wt％と高い溶銑を用い、適合例１と同
様の条件で脱燐・脱硫処理を行ったもの（Ａ）と、脱燐
フラックスの吹き込み速度を1.8 kg/min・ｔとした以外
は適合例１と同様の条件で脱燐・脱硫処理を行ったもの
（Ｂ）とについて、適合例１と同様の調査を行った。表
４に脱燐・脱硫処理後の溶銑の成分組成及び温度、表５
に脱燐処理後のスラグの成分組成を示す。Application Example 3 [A] which was subjected to dephosphorization / desulfurization treatment under the same conditions as in Application Example 1 using hot metal having a high [Si] concentration of 0.3 wt% (A) and a dephosphorization flux blowing rate of 1.8. The same investigation as in the conformity example 1 was carried out for the product (B) which was subjected to the dephosphorization / desulfurization treatment under the same conditions as in the conformity example 1 except that it was kg / min · t. Table 4 shows the composition and temperature of the hot metal after the dephosphorization / desulfurization treatment, and Table 5
The composition of the slag after dephosphorization is shown in Fig.
【００３３】[0033]
【表４】 [Table 4]
【００３４】[0034]
【表５】 [Table 5]
【００３５】比較例１ 脱燐期の底吹き酸素吹き込み速度を0.8 Ｎm3／min ・ｔ
とし、上吹き酸素の吹き込みを行わなかった以外は適合
例１と同様の脱燐・脱硫処理を施し、処理前後の溶銑の
成分組成及び温度を調査した。表６に脱燐・脱硫処理前
後の溶銑の成分組成及び温度を示す。Comparative Example 1 The bottom blowing oxygen blowing rate during the dephosphorization period was 0.8 Nm 3 / min · t.
Then, the same dephosphorization / desulfurization treatment as in the conforming example 1 was performed except that the top-blown oxygen was not blown, and the composition and temperature of the hot metal before and after the treatment were investigated. Table 6 shows the component composition and temperature of the hot metal before and after the dephosphorization / desulfurization treatment.
【００３６】[0036]
【表６】 [Table 6]
【００３７】比較例２ 脱燐期の底吹き酸素の吹き込み速度を0.48Ｎm3／min ・
ｔとし、上吹き酸素吹き込み速度を0.4 Ｎm3／min ・ｔ
として脱燐期及び脱硫期を通して６分間吹き込んだ以外
は適合例１と同様の方法で脱燐・脱硫処理を施し、処理
前後の溶銑の成分組成及び温度を調査した。（上吹きと
底吹きとの酸素原単位の比は3.3 ：6.7）。表７に脱燐
・脱硫処理前後の溶銑の成分組成及び温度を示す。Comparative Example 2 In the dephosphorization period, the blowing rate of bottom-blown oxygen was 0.48 Nm 3 / min.
and the top blowing oxygen blowing rate is 0.4 Nm 3 / min · t
As the above, a dephosphorization / desulfurization treatment was performed in the same manner as in the conforming example 1 except that the composition was blown for 6 minutes throughout the dephosphorization period and the desulfurization period, and the composition and temperature of the hot metal before and after the treatment were investigated. (Oxygen intensity ratio between top and bottom is 3.3: 6.7). Table 7 shows the composition and temperature of the hot metal before and after the dephosphorization / desulfurization treatment.
【００３８】[0038]
【表７】 [Table 7]
【００３９】以上、この発明の適合例は、いずれも処理
後溶銑の温度低下がなく高効率の脱燐・脱硫が達成さ
れ、上吹き酸素の吹き込みを脱燐期のみにすること（適
合例１と２との比較）、脱燐後のスラグの塩基度を2.0
以上にすること（適合例３の（Ａ）と（Ｂ）との比較）
により脱硫効率が明らかに向上していることが分かる。As described above, in any of the conforming examples of the present invention, high-efficiency dephosphorization / desulfurization can be achieved without lowering the temperature of the hot metal after the treatment, and the blowing of top-blown oxygen is performed only in the dephosphorization period (Compliant example 1 And 2), the basicity of the slag after dephosphorization is 2.0
Do the above (Comparison between (A) and (B) of Conformance Example 3)
It can be seen that the desulfurization efficiency is clearly improved.
【００４０】これらに対し、比較例１では酸素の上吹き
をしてないため処理後溶銑の温度が100 ℃以上も低下
し、上吹きと底吹きとの酸素原単位の比が3.3 ：6.7 と
この発明の限定範囲を外れる比較例２では特に脱燐効率
が劣っている。On the other hand, in Comparative Example 1, the temperature of the hot metal after the treatment decreased by 100 ° C. or more because the top blowing of oxygen was not performed, and the ratio of the oxygen basic unit of the top blowing to the bottom blowing was 3.3: 6.7. In Comparative Example 2, which is out of the limited range of the present invention, the dephosphorization efficiency is particularly poor.
【００４１】[0041]
【発明の効果】この発明は、上底吹き転炉を用い、底吹
き酸素吹き込み速度及び上吹きと底吹きとの酸素原単位
の比を特定して脱燐・脱硫処理を行うものであり、この
発明によれば、上底吹き転炉を用いるため上吹き及び底
吹きの酸素量を最適にコントロールすることが容易であ
り、トップスラグの脱硫能を阻害することのない脱燐処
理を行うことができるため、同一のフラックス原単位、
酸素原単位で溶銑温度を低下させることなく、かつ、脱
燐効率を損わずに高い脱硫効率を得ることができる。さ
らに、酸素の上吹きを行う時期、脱燐後のトップスラグ
の塩基度を最適にすることにより、より高い脱硫効率を
得ることができる。Industrial Applicability According to the present invention, a dephosphorization / desulfurization process is performed by using a top-bottom blowing converter and specifying the bottom-blowing oxygen blowing rate and the ratio of oxygen basic units of top-blowing and bottom-blowing. According to the present invention, since the top-bottom blowing converter is used, it is easy to optimally control the amount of oxygen in the top-blowing and bottom-blowing, and to perform the dephosphorization treatment that does not impair the desulfurization ability of the top slag. Because the same flux intensity,
A high desulfurization efficiency can be obtained without lowering the hot metal temperature by the oxygen unit and without degrading the dephosphorization efficiency. Further, by optimizing the basicity of the top slag after dephosphorization when oxygen is top-blown, higher desulfurization efficiency can be obtained.
【図１】底吹き酸素の大量吹き込みにおける溶銑の脱燐
メカニズムを示す説明図である。FIG. 1 is an explanatory view showing a dephosphorization mechanism of hot metal when a large amount of bottom-blown oxygen is blown.
【図２】底吹き酸素吹き込み速度と脱硫率との関係を示
すグラフである。FIG. 2 is a graph showing a relationship between a bottom-blown oxygen blowing rate and a desulfurization rate.
【図３】上吹きと底吹きとの酸素原単位の比と脱燐量、
同時脱硫率及び溶銑の温度低下量との関係を示すグラフ
である。FIG. 3 is a ratio of oxygen basic unit between top blowing and bottom blowing and dephosphorization amount,
It is a graph which shows the relationship between the simultaneous desulfurization rate and the amount of temperature decrease of hot metal.
【図４】上吹き酸素原単位の（脱硫期）／（脱燐期＋脱
硫期）の値と脱硫率との関係を示すグラフである。FIG. 4 is a graph showing the relationship between the value of (desulfurization period) / (desulfurization period + desulfurization period) of the basic unit of top-blown oxygen and the desulfurization rate.
【図５】上吹き酸素原単位の（脱硫期）／（脱燐期＋脱
硫期）の値と溶銑温度低下量との関係を示すグラフであ
る。FIG. 5 is a graph showing the relationship between the value of (desulfurization period) / (desulfurization period + desulfurization period) of the basic unit of top-blown oxygen and the amount of decrease in hot metal temperature.
【図６】脱燐後のスラグの塩基度とその後の脱硫処理に
おける脱硫率との関係を示すグラフである。FIG. 6 is a graph showing the relationship between the basicity of slag after dephosphorization and the desulfurization rate in the subsequent desulfurization treatment.
Claims (3)
から精錬剤を溶銑中に吹き込み脱燐及び脱硫を行う溶銑
処理方法において、 上底吹き転炉を用い、底吹きにより酸素あるいは酸素と
その他のガスの混合ガスによって生石灰系フラックスを
吹き込む脱燐処理と、それに引き続いて非酸化性ガスを
用いて生石灰系フラックスを吹き込む脱硫処理とを酸素
の上吹きを付加して行い、かつ、上記脱燐期の底吹き酸
素吹き込み速度を0.2 Nm3/min ・ｔ以上とし、上吹き酸
素原単位（Nm3/t)と底吹き酸素原単位（Ｎm3／ｔ）との
比を３：７から１：９の範囲に調整することを特徴とす
る溶銑の脱燐・脱硫法。1. A hot metal treatment method in which a refining agent is blown into hot metal from a tuyere provided below a hot metal bath surface using a converter to perform dephosphorization and desulfurization, and oxygen is blown by bottom blowing using a top-bottom blowing converter. Alternatively, a dephosphorization treatment in which quicklime-based flux is blown by a mixed gas of oxygen and other gas, and a desulfurization treatment in which a quicklime-based flux is subsequently blown in using a non-oxidizing gas are performed by additionally blowing oxygen, and In the above dephosphorization period, the bottom blowing oxygen blowing rate is 0.2 Nm 3 / min · t or more, and the ratio of the top blowing oxygen basic unit (Nm 3 / t) and the bottom blowing oxygen basic unit (Nm 3 / t) is 3 : A method for dephosphorizing and desulfurizing hot metal, which is characterized by adjusting the range to 7 to 1: 9.
を特徴とする請求項１に記載の溶銑の脱燐・脱硫法。2. The method for dephosphorizing and desulfurizing hot metal according to claim 1, wherein the upper blowing of oxygen is performed only during the dephosphorization period.
O2（wt％）であらわす塩基度が2.0 以上であることを特
徴とする請求項１又は２に記載の溶銑の脱燐・脱硫法。3. CaO (wt%) / Si of slag after dephosphorization treatment
The basicity represented by O 2 (wt%) is 2.0 or more, and the method for dephosphorizing and desulfurizing hot metal according to claim 1 or 2.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15088894A JP3505791B2 (en) | 1994-07-01 | 1994-07-01 | Dephosphorization and desulfurization of hot metal |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15088894A JP3505791B2 (en) | 1994-07-01 | 1994-07-01 | Dephosphorization and desulfurization of hot metal |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0813016A true JPH0813016A (en) | 1996-01-16 |
| JP3505791B2 JP3505791B2 (en) | 2004-03-15 |
Family
ID=15506583
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP15088894A Expired - Fee Related JP3505791B2 (en) | 1994-07-01 | 1994-07-01 | Dephosphorization and desulfurization of hot metal |
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| Country | Link |
|---|---|
| JP (1) | JP3505791B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010084154A (en) * | 2008-09-29 | 2010-04-15 | Sumitomo Metal Ind Ltd | Method for dephosphorizing molten iron |
| CN103924025A (en) * | 2014-03-27 | 2014-07-16 | 东北大学 | Method for pre-desulfuration of combined-blowing molten iron at top and bottom in ladle |
| JP2020105540A (en) * | 2018-12-26 | 2020-07-09 | 日本製鉄株式会社 | Molten iron dephosphorization method |
-
1994
- 1994-07-01 JP JP15088894A patent/JP3505791B2/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010084154A (en) * | 2008-09-29 | 2010-04-15 | Sumitomo Metal Ind Ltd | Method for dephosphorizing molten iron |
| CN103924025A (en) * | 2014-03-27 | 2014-07-16 | 东北大学 | Method for pre-desulfuration of combined-blowing molten iron at top and bottom in ladle |
| JP2020105540A (en) * | 2018-12-26 | 2020-07-09 | 日本製鉄株式会社 | Molten iron dephosphorization method |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3505791B2 (en) | 2004-03-15 |
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