JP5234124B2 - Refining method and method for producing molten steel - Google Patents
Refining method and method for producing molten steel Download PDFInfo
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- JP5234124B2 JP5234124B2 JP2011038279A JP2011038279A JP5234124B2 JP 5234124 B2 JP5234124 B2 JP 5234124B2 JP 2011038279 A JP2011038279 A JP 2011038279A JP 2011038279 A JP2011038279 A JP 2011038279A JP 5234124 B2 JP5234124 B2 JP 5234124B2
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Description
本発明は、転炉において溶湯に対して脱燐剤を吹き込むことなく、脱燐反応や脱燐脱炭反応を行わせることで脱燐精錬または脱燐脱炭精錬を行なう精錬方法、及びその精錬方法を採用した溶鋼の製造方法に関する。 The present invention relates to a refining method for performing dephosphorization or dephosphorization and decarburization by causing a dephosphorization reaction or a dephosphorization and decarburization reaction without blowing a dephosphorization agent into the molten metal in a converter, and a refining method therefor The present invention relates to a method for producing molten steel employing the method.
例えば、脱燐剤としてＣａＯ含有脱燐剤を考えた場合、転炉における酸化カルシウムによる脱燐反応は下記の式（１）で表される。
３（ＣａＯ）＋５（ＦｅＯ）＋２［Ｐ］
＝（３ＣａＯ・Ｐ２Ｏ５）＋５［Ｆｅ］ ・・・式（１）
ここで、
（）：スラグ成分
［］：溶湯中成分
である。
For example, when a CaO-containing dephosphorizing agent is considered as the dephosphorizing agent, the dephosphorization reaction by calcium oxide in the converter is represented by the following formula (1).
3 (CaO) +5 (FeO) +2 [P]
= (3CaO · P 2 O 5 ) +5 [Fe] (1)
here,
(): Slag component []: Component in molten metal
転炉において脱燐または脱燐脱炭精錬を行なう場合、塊状の脱燐剤ＣａＯを転炉に投入する方法が一般的である。このとき、脱燐反応効率の向上には、ＣａＯが溶融しまた脱Ｐに必要なＦｅＯレベルが維持されることが必要である。また、ＣａＯの融点は約２５７０℃であり、溶融促進のための添加剤として例えば蛍石（ＣａＦ２）等のハロゲン系化合物やアルカリ系化合物が用いられてきた。しかしこれらの化合物は化学的に活性でありスラグ再利用上制約がある。また例えば蛍石は含有するフッ素により処理が困難となり、脱燐処理コストの増大をもたらす。
その解決策として、例えば特許文献１〜３に記載のように脱燐剤であるＣａＯを粉状（粉体）にして上吹きランスから溶湯に吹き付ける方法がある。
When dephosphorization or dephosphorization and decarburization refining is performed in a converter, a method in which a bulk dephosphorization agent CaO is introduced into the converter is common. At this time, in order to improve the dephosphorization reaction efficiency, it is necessary that CaO is melted and the FeO level necessary for de-P is maintained. CaO has a melting point of about 2570 ° C., and halogen compounds such as fluorite (CaF 2 ) and alkali compounds have been used as additives for promoting melting. However, these compounds are chemically active and have limitations on slag reuse. Further, for example, fluorite becomes difficult to treat due to the fluorine contained therein, resulting in an increase in dephosphorization cost.
As a solution, for example, as described in Patent Documents 1 to 3, there is a method in which CaO, which is a dephosphorizing agent, is powdered (powder) and sprayed from the top blowing lance onto the molten metal.
粉状のＣａＯ（脱燐剤）を転炉型反応容器内の溶銑（溶湯）に吹き付ける方法を採用する場合には、吹き付けのための設備が必要となる。
また、吹き付けの際にはＣａＯの粒度や吹き付け速度に制約があるという問題点を有する。例えば、吹き付け速度を遅くしすぎると酸化カルシウム粉による配管閉塞や溶銑の脱炭不良・脱燐不良などの原因となる。一方、吹き込み速度を早くし過ぎると酸化カルシウムの転炉外飛散による粉塵問題への影響が懸念される。このため、精錬設備等の条件に応じて、用いる酸化カルシウム粉粒度と、キャリアガスとなる吹き付け酸素速度との関係が最適となる範囲を求め、そのような最適範囲となるように制御する必要がある。しかし、これらの制約・問題を解決するには莫大な投資が必要である。
In the case of adopting a method of spraying powdered CaO (dephosphorizing agent) onto the molten iron (molten metal) in the converter reactor, equipment for spraying is required.
In addition, there is a problem that there are restrictions on the CaO grain size and spraying speed when spraying. For example, if the spraying speed is too slow, it may cause piping blockage due to calcium oxide powder, poor decarburization / dephosphorization of hot metal, and the like. On the other hand, if the blowing speed is increased too much, there is a concern about the influence on the dust problem due to the scattering of calcium oxide outside the converter. For this reason, it is necessary to obtain a range in which the relationship between the calcium oxide powder particle size to be used and the blowing oxygen speed to be the carrier gas is optimal, and to control such an optimal range according to the conditions of the refining equipment, etc. is there. However, enormous investment is required to solve these restrictions and problems.
吹き付けを用いる脱燐方法の改良として、吹き付けと併用してＣａＯ含有物質を溶銑装入前の転炉に前置き（装入）しておく方法もある（特許文献２、３参照）。しかしこの場合でも、上吹きによるＣａＯ添加を必須とする。
また従来、上吹きＣａＯ添加を行なわない場合には、前置き法を含むＣａＯの好適な添加条件は明確になっておらず、効果的な脱燐方法の開発が必要とされていた。
As an improvement of the dephosphorization method using spraying, there is also a method in which a CaO-containing material is preliminarily placed (charged) in a converter before hot metal charging (see Patent Documents 2 and 3). However, even in this case, CaO addition by top blowing is essential.
Conventionally, when no top-blown CaO addition is performed, suitable addition conditions for CaO including the pre-treatment method have not been clarified, and development of an effective dephosphorization method has been required.
ここで、上吹きＣａＯ添加を行なわないで精錬を実施する場合には、転炉に装入された溶銑（溶湯）上に塊状のＣａＯを投入する方法が一般的である。塊状のＣａＯを投入するのは、粉状のＣａＯを投入した場合には当該粉状のＣａＯが溶銑（溶湯）に浮いてしまい、ＣａＯと溶銑との混合が不十分になるためである。このように、脱燐剤の吹き付けを実施しない場合には、篩い等によって粉状の脱燐剤を除いた後の塊状の脱燐剤を使用している。そして、従来にあっては、粉状のＣａＯの好適な使用方法については確立されていなかった。 Here, when refining is carried out without adding top-blowing CaO, a method of pouring massive CaO onto the molten iron (molten metal) charged in the converter is common. The reason why the massive CaO is added is that when powdered CaO is charged, the powdered CaO floats on the molten iron (molten metal), and mixing of CaO and molten iron becomes insufficient. Thus, when spraying of the dephosphorizing agent is not carried out, the bulk dephosphorizing agent after removing the powdery dephosphorizing agent by sieving or the like is used. And conventionally, the suitable usage method of powdery CaO has not been established.
一般に塊状のＣａＯは、粉砕し、篩い分け処理により所定の粒度範囲の塊状に調製する。この塊状のＣａＯ生産工程において粉状のＣａＯが副生されるが、上吹きＣａＯ設備のない設備においては、粉状のＣａＯを脱燐剤として有効に利用することができないという問題もあった。
本発明は、上記のような点に着目したもので、転炉精錬において、脱燐剤の吹き付けを行なう設備が無くても、効率よく転炉操業を行なうための精錬方法及び溶鋼の製造方法を提供することを目的としている。
In general, massive CaO is pulverized and prepared into a massive particle size range by sieving. In this bulk CaO production process, powdery CaO is produced as a by-product, but there is also a problem that the powdered CaO cannot be effectively used as a dephosphorizing agent in the equipment without the top blown CaO equipment.
The present invention pays attention to the above points, and in a refining process, a refining method and a molten steel production method for efficiently performing a converter operation without a facility for spraying a dephosphorizing agent. It is intended to provide.
上記課題を解決するために、本発明のうち請求項１に記載した発明は、溶湯への脱燐剤の吹き付けを行なうことなく脱燐精錬または脱燐脱炭精錬を行なう精錬方法において、粒径が５ｍｍ以下の粉体が含まれる第１の脱燐剤を反応容器に装入した後に、上記反応容器に溶銑を装入し、上記溶銑の装入後に第２の脱燐剤を反応容器に装入し、溶湯への脱燐剤の吹き付けを行なうことなく精錬を行なうことを特徴とする。
次に、請求項２に記載した発明は、溶湯への脱燐剤の吹き付けを行なうことなく脱燐精錬または脱燐脱炭精錬を行なう精錬方法において、スクラップ及び粒径が５ｍｍ以下の粉体が含まれる第１の脱燐剤を反応容器に装入した後に、上記反応容器に溶銑を装入し、上記溶銑の装入後に第２の脱燐剤を反応容器に装入し、溶湯への脱燐剤の吹き付けを行なうことなく精錬を行なうことを特徴とする。
In order to solve the above problems, the invention is the refining method of performing dephosphorization refining or dephosphorization decarburization refining without performing blowing of dephosphorization agent into the melt according to claim 1 of the present invention, the particle size After charging the reaction vessel with the first dephosphorizing agent containing powder of 5 mm or less , the hot metal is charged into the reaction vessel, and after the hot metal is charged, the second dephosphorizing agent is put into the reaction vessel. It is characterized by charging and refining without spraying a dephosphorizing agent to the molten metal .
Next, the invention described in claim 2 is the refining method of performing dephosphorization refining or dephosphorization decarburization refining without performing blowing of dephosphorization agent into the melt scrap and particle size are less powder 5mm After charging the first dephosphorizing agent contained in the reaction vessel, the molten metal is charged into the reaction vessel, and after the molten metal is charged, the second dephosphorizing agent is charged into the reaction vessel, It is characterized by refining without spraying a dephosphorizing agent .
次に、請求項３に記載した発明は、請求項１又は請求項２に記載した構成に対し、上記溶銑装入前に装入する第１の脱燐剤のうちの９０質量％以上の脱燐剤は粒径が５ｍｍ以下の脱燐剤であり、且つ、上記溶銑装入前に装入する第１の脱燐剤の量は、上記精錬処理全体で使用する脱燐剤全体の１０質量％以上であることを特徴とする。
次に、請求項４に記載した発明は、請求項１〜請求項３のいずれか１項に記載に精錬方法で精錬したことを特徴とする溶鋼の製造方法を提供するものである。
Next, the invention described in claim 3 is directed to the structure described in claim 1 or claim 2, wherein 90% by mass or more of the first dephosphorizing agent charged before the hot metal charging is removed . The phosphorus agent is a dephosphorizing agent having a particle size of 5 mm or less, and the amount of the first dephosphorizing agent charged before the hot metal charging is 10 mass of the total dephosphorizing agent used in the entire refining treatment. % Or more.
Next, invention of Claim 4 provides the manufacturing method of the molten steel characterized by refining by the refining method of any one of Claims 1-3.
本発明によれば、転炉精錬において、脱燐剤の吹き付け設備が無くても、粉状の脱燐剤を有効に脱燐剤として利用して精錬を行うことが可能となる。
そして、本発明の方法によれば、例えば、転炉精錬において転炉型反応容器内への別投入という方法を取ることで、上吹きランスからの吹き付けを実施しなくても酸化カルシウム粉（粉状の脱燐剤）を使用することができる。また本発明の方法によれば、上吹き設備のための設備投資をしなくても、またハロゲン系化合物やアルカリ系化合物を使用しなくても、従来の酸化カルシウム塊を脱燐剤として使用する際の効率を向上させることが可能になる。
ADVANTAGE OF THE INVENTION According to this invention, in converter refining, even if there is no facility for spraying a dephosphorizing agent, it is possible to perform refining using a powdery dephosphorizing agent effectively as a dephosphorizing agent.
And according to the method of the present invention, for example, by adopting a method of separate charging into a converter type reactor in converter refining, calcium oxide powder (powder) can be used without spraying from the top blowing lance. Can be used. In addition, according to the method of the present invention, the conventional calcium oxide lump is used as a dephosphorizing agent without investing in equipment for top blowing equipment and without using halogen compounds or alkali compounds. Efficiency can be improved.
次に、本発明の実施形態について図面を参照して説明する。
（精錬方法について）
本実施形態の精錬方法では、溶銑を転炉型反応容器に装入する前に、当該反応容器に対し粉体が含まれる脱燐剤を投入（装入）する。その後、反応容器に対して溶銑を装入し精錬を開始する。上記溶銑の装入後であって精錬の開始前若しくは精錬中にも適宜脱燐剤を溶湯に投入して精錬を実施する。
Next, embodiments of the present invention will be described with reference to the drawings.
(About refining method)
In the refining method of the present embodiment, before the molten iron is charged into the converter reactor, a dephosphorizing agent containing powder is charged into the reactor. Thereafter, hot metal is charged into the reaction vessel and refining is started. After the above hot metal is charged and before refining is started or during refining, a dephosphorizing agent is appropriately added to the molten metal for refining.
また、溶銑にスクラップを混入して精錬を実施する場合には、まず転炉型反応容器にスクラップを投入した後に、当該反応容器内に、少なくとも粉体が含まれる脱燐剤を投入する。その後、反応容器に対して溶銑を装入し精錬を開始する。上記溶銑の装入後であって精錬の開始前若しくは精錬中にも適宜脱燐剤を投入して精錬を実施する。
なお、溶銑装入前に事前に装入するスクラップ及び脱燐剤については、スクラップの前に脱燐剤を投入しても良い。但し、スクラップを先に装入した方が脱燐剤と溶銑の接触がよくなりやすいので、脱燐剤を装入後にスクラップを装入するよりも好ましい。
In addition, when refining is performed by mixing scrap into molten iron, first, scrap is put into a converter reactor, and then a dephosphorizing agent containing at least powder is put into the reactor. Thereafter, hot metal is charged into the reaction vessel and refining is started. After the above hot metal is charged and before the start of refining or during refining, a dephosphorizing agent is appropriately added to carry out refining.
In addition, about the scrap and dephosphorization agent charged in advance before hot metal charging, you may throw in a dephosphorization agent before a scrap. However, it is preferable to charge the scrap first, rather than charging the scrap after the dephosphorizing agent is put in since the contact between the dephosphorizing agent and the hot metal is likely to be improved.
一般に塊状のＣａＯは、粉砕し、篩い分け処理により所定の粒度範囲の塊状に調製する。この塊状のＣａＯ生産工程において粉状のＣａＯが副生される。この副生された粉状（粉体）のＣａＯを、溶銑装入前に装入する脱燐剤として積極的に使用する。
ここで、精錬で使用する脱燐剤の全体量は、精錬する溶銑の分析値（スクラップを使用する場合には、溶銑およびスクラップの分析値）と、精錬後の目標Ｐ濃度とに基づき脱Ｐ必要量を定める。そして、その定めた脱Ｐ必要量から、精錬処理全体で投入すべき脱燐剤の量を決定する。なお、精錬全体での脱燐剤使用量は、実績の脱燐剤量と脱燐量の関係からも求めることができる。
In general, massive CaO is pulverized and prepared into a massive particle size range by sieving. Powdered CaO is by-produced in this massive CaO production process. The powdery (powder) CaO produced as a by-product is positively used as a dephosphorizing agent to be charged before hot metal charging .
Here, the total amount of the dephosphorizing agent used in refining is determined based on the analysis value of the hot metal to be refined (in the case of using scrap, the analysis value of hot metal and scrap) and the target P concentration after refining. Determine the required amount. Then, the amount of the dephosphorizing agent to be introduced in the entire refining process is determined from the determined amount of de-P required. The amount of the dephosphorizing agent used in the entire refining can also be determined from the relationship between the actual amount of dephosphorizing agent and the amount of dephosphorizing.
そして、上記決定した精錬処理全体で投入すべき脱燐剤の量のうち、１０質量％以上の脱燐剤（粉体を含む。）を、溶銑を投入する前に投入する脱燐剤として設定する。なお、溶銑投入前に投入する脱燐剤を事前の脱燐剤とも呼ぶ。
残りの脱燐剤は、溶銑を装入後に上記反応容器内に投入する。その後、酸素を吹き込み吹錬開始する。なお、吹き込みガスは、Ａｒ、Ｎ２、ＣＯや、それらの混合物であってもよい。残りの脱燐剤には、例えば粒径５〜３０ｍｍまたは５〜５０ｍｍの塊状を使用する。この塊状の脱燐剤の一部は、吹錬中に投入してもよい。
上記脱燐剤はＣａＯを含む脱燐剤が使用できるが、実質的にＣａＯからなる脱燐剤が好ましい。
Then, 10% by mass or more of the dephosphorizing agent (including powder) out of the amount of dephosphorizing agent to be added in the entire refining process determined above is set as the dephosphorizing agent to be added before the molten iron is added. To do. In addition, the dephosphorization agent thrown in before hot metal pouring is also called prior dephosphorization agent.
The remaining dephosphorizing agent is charged into the reaction vessel after the hot metal is charged. Thereafter, oxygen is blown in and blowing is started. The blown gas may be Ar, N 2 , CO, or a mixture thereof. For the remaining dephosphorizing agent, for example, a mass having a particle size of 5 to 30 mm or 5 to 50 mm is used. A part of the bulk dephosphorizing agent may be added during blowing.
As the dephosphorizing agent, a dephosphorizing agent containing CaO can be used, but a dephosphorizing agent consisting essentially of CaO is preferable.
また、溶銑装入前に事前に装入する脱燐剤は、上述のように全体の１０質量％以上が好ましい。１０質量％以下では効果が小さい。また、事前に装入する脱燐剤は、量が多すぎると溶銑と混ざりきらずに粉が浮上してしまったり、飛散が多くなってしまったりするおそれがあるので、４０質量％以下が好適である。
事前装入する脱燐剤の粒度は、精錬上は、細かいほど好ましい。ただし、細かくしすぎると粉砕コストがかかるうえ、ハンドリング過程での発塵の問題があるので、必要以上に細かくする必要はない。一方、粒度が粗いと脱燐剤の溶融が遅く分散も悪くなるうえ、精錬中にスラグフォーミングが起こりやすくなる。以上のことから、事前装入する脱燐剤は、粒径が５ｍｍ以下の脱燐剤が９０質量％以上を占めることが好ましい。粒径が５ｍｍ以下の脱燐剤とは、粉体の脱燐剤が実質含まれることを意味する。
Further, the dephosphorizing agent charged in advance before the hot metal charging is preferably 10% by mass or more of the whole as described above. The effect is small at 10% by mass or less. In addition, if the amount of the dephosphorizing agent to be charged in advance is too large, it may not be mixed with the hot metal and the powder may float or the amount of scattering may increase. is there.
The finer the particle size of the dephosphorizing agent charged in advance, the better in terms of refining. However, if it is too fine, there is a cost for pulverization and there is a problem of dust generation in the handling process, so there is no need to make it finer than necessary. On the other hand, if the particle size is coarse, melting of the dephosphorizing agent is slow and dispersion is also worsened, and slag forming is likely to occur during refining. From the above, it is preferable that the dephosphorizing agent to be charged in advance is 90% by mass or more of the dephosphorizing agent having a particle size of 5 mm or less. The dephosphorizing agent having a particle size of 5 mm or less means that the powdered dephosphorizing agent is substantially contained.
（本実施形態の効果）
次に、本実施形態における精錬方法による効果発現のメカニズムを説明する。
粉状の脱燐剤としてのＣａＯは、塊状のＣａＯに比べ溶銑とよく混合するので脱燐効果が大きい。しかし、ＣａＯ吹き付け設備がない場合、粉状のＣａＯを単に溶銑に投入しただけでは粉状のＣａＯが浮いてしまい、ＣａＯと溶銑が良く混合せず、反応に寄与しにくいだけではなく、粉塵飛散による環境悪化が発生する。
(Effect of this embodiment)
Next, the mechanism of effect expression by the refining method in this embodiment will be described.
CaO as a powdery dephosphorizing agent has a greater dephosphorizing effect because it mixes well with hot metal compared to bulk CaO. However, when there is no CaO spraying equipment, powdered CaO floats by simply adding powdered CaO to the hot metal, and CaO and hot metal do not mix well, making it difficult to contribute to the reaction. Environmental degradation due to
これに対し、発明者らは、粉状のＣａＯを転炉に事前装入しておき、そこに溶銑を添加すると溶銑との混合効果が効果的に発現することを見出した。この知見に基づき本発明では、溶銑装入前に粉体を含む脱燐剤を投入することで、ＣａＯ吹き込みを実施しなくても、脱燐効果を向上させることが出来た。
ここで、粉状のＣａＯを事前に装入しておくことで、その後、溶銑を装入した際における混合攪拌が強化され、上記脱燐反応の反応速度の向上とともに、スラグヘのＰ（燐）の吸収も早くなる。この結果、精錬に使用する全ＣａＯ消費量を減らすことができるものと考えられる。
On the other hand, the inventors have found that when powdered CaO is pre-charged into a converter and hot metal is added thereto, a mixing effect with the hot metal is effectively expressed. Based on this knowledge, in the present invention, the dephosphorization effect can be improved without introducing CaO by introducing a dephosphorization agent containing powder before hot metal charging.
Here, the powdered CaO is charged in advance, whereby the mixing and stirring when the molten iron is charged is strengthened, and the reaction rate of the dephosphorization reaction is improved, and P (phosphorus) in the slag is added. Absorption is also accelerated. As a result, it is considered that the total amount of CaO used for refining can be reduced.
なお、本発明の方法とは異なる脱燐投入方法である、ＣａＯ吹き込み設備を有し吹き込みによっても脱燐剤を投入する場合にあっては、粉状のＣａＯは吹き込みに主に使用されている。このため、転炉へのＣａＯの事前装入を併用する場合であっても、事前装入すべきＣａＯの条件については明らかでなかった。
これに対し、本発明においては、ＣａＯ吹き込みを行わない条件で、事前装入すべきＣａＯの好適な条件を明確にすることで、上述のような効果を得ることが出来る。
また、脱燐剤の吹き込みを実施しない場合に、脱燐剤として敬遠されていた粉体のＣａＯを積極的に使用することが出来るという効果もある。
In the case where the dephosphorization charging method is different from the method of the present invention and the CaO blowing equipment is provided and the dephosphorizing agent is also charged by blowing, powdered CaO is mainly used for blowing. . For this reason, even when it was used together with the pre-charging of CaO into the converter, the conditions of CaO to be pre-charged were not clear.
On the other hand, in the present invention, the above-described effects can be obtained by clarifying suitable conditions of CaO to be charged in advance under the condition where CaO blowing is not performed.
In addition, there is also an effect that when the dephosphorizing agent is not blown, the powdered CaO which has been avoided as a dephosphorizing agent can be used positively.
粒径５ｍｍ以下のＣａＯ（粉体を含むＣａＯ）を９８質量％有する粒度のＣａＯを事前に１〜４トン、３３０トン転炉に装入した後、溶銑（成分Ｃ：３．８〜４．４質量％、Ｓｉ：０．０５〜０．４０質量％、Ｐ：０．０９〜０．１２質量％）３３０トンを上記転炉に装入した。 After preliminarily charging 1 to 4 tons and 330 tons of CaO having a particle size of 98 mass% of CaO having a particle diameter of 5 mm or less (CaO containing powder), hot metal (component C: 3.8 to 4. (4 mass%, Si: 0.05-0.40 mass%, P: 0.09-0.12 mass%) 330 tons was charged into the converter.
その後５〜５０ｍｍの塊状のＣａＯ：３〜５トンを溶銑上に投入し、また副原料（軽焼ドロマイト：１．５トン）を溶銑上に投入して、上吹き酸素流量４５〜６０Ｎｍ３／ｔ、底吹き酸素流量５〜８Ｎｍ３／ｔの条件で吹錬を実施した。また、吹錬中に５〜５０ｍｍのＣａＯ：３〜８トンを溶銑上に投入して、１８〜２５分間吹錬し、出鋼した。この時の全ＣａＯ量に対する事前装入した粉体を含むＣａＯの質量比率（粉ＣａＯ前置き比率）は５〜２３質量％であり、精錬終了後の鋼の分析値はＣ：０．０２５〜０．０４５質量％、Ｓｉ＜０．０１質量％、Ｐ：０．０１３〜０．０２５質量％であった。
以上の精錬で使用した全ＣａＯ量と脱燐量（ΔＰ＝溶銑Ｐ濃度−出鋼Ｐ濃度）の関係を図１に実線（●）で示す。
Thereafter, 5 to 50 mm of massive CaO: 3 to 5 tons is charged onto the hot metal, and an auxiliary material (light calcined dolomite: 1.5 tons) is charged onto the hot metal, and the top blown oxygen flow rate is 45 to 60 Nm 3 / t, Blowing was carried out under conditions of a bottom blowing oxygen flow rate of 5 to 8 Nm 3 / t. Further, 5 to 50 mm of CaO: 3 to 8 tons was put on the hot metal during blowing, and the steel was blown for 18 to 25 minutes to produce steel. The mass ratio of CaO including the pre-charged powder to the total CaO amount at this time (powder CaO pre-ratio) is 5 to 23% by mass, and the analysis value of the steel after refining is C: 0.025 to 0 0.045% by mass, Si <0.01% by mass, P: 0.013 to 0.025% by mass.
The relationship between the total CaO amount used in the above refining and the dephosphorization amount (ΔP = molten iron P concentration−steel P concentration) is shown by a solid line (●) in FIG.
「比較例１−１」
次に、ＣａＯの事前装入をすることなく、全量のＣａＯ（粒径５〜５０ｍｍの全て塊状の脱燐剤）を、転炉に溶銑を装入した後に投入した。精錬の操業は、上記実施例１と同じ操業とした。
このときの、精錬で使用した全ＣａＯ量と脱燐量（ΔＰ＝溶銑Ｐ−出鋼Ｐ）の関係を図１に点線（◇）で示す。
"Comparative Example 1-1"
Next, without pre-charging CaO, the entire amount of CaO (all bulk dephosphorization agent having a particle size of 5 to 50 mm) was charged after the molten iron was charged into the converter. The refining operation was the same as in Example 1 above.
The relationship between the total amount of CaO used in the refining and the amount of dephosphorization (ΔP = molten iron P−steel P) is shown by a dotted line (◇) in FIG.
「比較例１−２」
実施例１における粒径５ｍｍ以下の粉体を含むＣａＯの代わりに、溶銑投入前に５〜５０ｍｍの全てが塊状のＣａＯ塊を事前に投入する以外は、上記実施例１と同じ操業を行った。
その結果を図１に一点鎖線（▲）で示す。
図１に示すように、比較例１−１及び比較例１−２に比べて、実施例１による精錬方法の方が、同じＣａＯ使用量に対する脱燐量が高いことが分かる。
"Comparative Example 1-2"
Instead of CaO containing powder having a particle size of 5 mm or less in Example 1, the same operation as in Example 1 was performed except that all 5-50 mm of massive CaO lump was charged in advance before molten metal was charged. .
The result is shown by a one-dot chain line (▲) in FIG.
As shown in FIG. 1, it can be seen that the refining method according to Example 1 has a higher amount of dephosphorization with respect to the same amount of CaO used than Comparative Example 1-1 and Comparative Example 1-2.
次に、スクラップ５０トンを３３０トン転炉に装入後、粒径５ｍｍ以下の比率が９５質量％である粒度のＣａＯ：２トンを上記転炉に装入し、その後、溶銑２８０トンを上記転炉に装入した。この時の溶銑とスクラップ合計での成分は、Ｃ：３．６質量％、Ｓｉ：０．０８質量％、Ｐ：０．１０質量％であった。
その後５〜５０ｍｍの塊状のＣａＯ：５トンを溶銑上に投入し、また副原料（種類軽焼ドロマイト：２トン）を溶銑上に投入して、上吹き酸素流量５３Ｎｍ３／ｔ、底吹き酸素流量６Ｎｍ３／ｔの条件で吹錬を実施した。また、吹錬中に５〜５０ｍｍのＣａＯ：６トンを溶銑上に投入して、２２分間吹錬し、出鋼した。
精錬終了後の鋼の分析値はＣ：０．０３５質量％、Ｓｉ＜０．０１質量％、Ｐ：０．０１５質量％であり脱燐量は０．０８５質量％であった。
Next, after charging 50 tons of scrap into a 330-ton converter, 2 tons of CaO having a particle size of 95% by mass with a particle size of 5 mm or less was charged into the converter, and then 280 tons of hot metal was added to the above-mentioned converter Charged to the converter. The components in the hot metal and scrap total at this time were C: 3.6 mass%, Si: 0.08 mass%, and P: 0.10 mass%.
Thereafter, 5 tons of massive CaO of 5 to 50 mm are put on the hot metal, and auxiliary materials (type light burned dolomite: 2 tons) are put on the hot metal, and the top blown oxygen flow rate is 53 Nm 3 / t, bottom blown oxygen Blowing was performed at a flow rate of 6 Nm 3 / t. In addition, 5 to 50 mm of CaO: 6 tons was put on the hot metal during blowing, and the steel was blown for 22 minutes to produce steel.
The analytical values of the steel after refining were C: 0.035% by mass, Si <0.01% by mass, P: 0.015% by mass, and the dephosphorization amount was 0.085% by mass.
「比較例２」
次に、ＣａＯの事前装入をすることなく、総ＣａＯ量は実施例２と同じとして全量のＣａＯ（粒径５〜５０ｍｍ）を、転炉にスクラップおよび溶銑を装入した後に添加した。精錬の操業は、上記実施例２と同じ操業とした。
この場合、脱燐量は０．０７１質量％となっており、実施例２に比べて脱燐量が小さかった。
“Comparative Example 2”
Next, without pre-charging CaO, the total amount of CaO was the same as in Example 2, and the entire amount of CaO (
In this case, the amount of dephosphorization was 0.071% by mass, and the amount of dephosphorization was smaller than that in Example 2.
「比較例３」
実施例２における粒径５ｍｍ以下のＣａＯ粉の代わりに、溶銑投入前に５〜５０ｍｍのＣａＯ塊を事前に投入する以外は、上記実施例２と同じ操業を行った。
この場合には、脱燐量は０．０７７質量％となっており、比較例２と実施例２の中間の脱燐量となった。
“Comparative Example 3”
Instead of CaO powder having a particle size of 5 mm or less in Example 2, the same operation as in Example 2 was performed, except that 5-50 mm of CaO lump was added in advance before hot metal was charged.
In this case, the amount of dephosphorization was 0.077% by mass, which was an intermediate amount of dephosphorization between Comparative Example 2 and Example 2.
上記実施例１と同じ操業において、ＣａＯの事前投入量を変化させたときの脱燐量を求めてみた。そのときの結果を図２に示す。
図２から分かるように、ＣａＯが１０％を超えると脱燐量が大きくなることが分かる。
In the same operation as in Example 1, the amount of dephosphorization was determined when the pre-charge amount of CaO was changed. The result at that time is shown in FIG.
As can be seen from FIG. 2, the amount of dephosphorization increases when CaO exceeds 10%.
上記実施例１と同じ操業において、上吹き酸素流量を２２Ｎｍ３／ｔに減らし、吹錬時間を１０分として、脱炭を抑えた条件で脱燐を行なった。溶鋼温度は１４００℃と、通常の脱燐脱炭操業の場合よりも約２５０℃低く、精錬終了後の鋼の成分はＣ：２〜４質量％、Ｐ：０．０１〜０．０４質量％となった。この時の脱燐量は、同様の操業において粉を含むＣａＯを前置きしなかった場合の精錬終了後の脱燐量に比べて約０．０１質量％向上していた。
In the same operation as in Example 1, the top blown oxygen flow rate was reduced to 22 Nm 3 / t, the blowing time was set to 10 minutes, and dephosphorization was performed under conditions where decarburization was suppressed. The molten steel temperature is 1400 ° C., which is about 250 ° C. lower than in the case of normal dephosphorization and decarburization operations, and the steel components after refining are C: 2-4 mass%, P: 0.01-0.04 mass% It became. The amount of dephosphorization at this time was improved by about 0.01% by mass compared to the amount of dephosphorization after completion of refining in the same operation when CaO containing powder was not placed in advance.
Claims (4)
粒径が５ｍｍ以下の粉体が含まれる第１の脱燐剤を反応容器に装入した後に、上記反応容器に溶銑を装入し、上記溶銑の装入後に第２の脱燐剤を反応容器に装入し、溶湯への脱燐剤の吹き付けを行なうことなく精錬を行なうことを特徴とする精錬方法。 In a refining method for performing dephosphorization or dephosphorization and decarburization without spraying a dephosphorizing agent to the molten metal,
After the first dephosphorization agent containing powder having a particle size of 5 mm or less is charged into the reaction vessel, the hot metal is charged into the reaction vessel, and the second dephosphorization agent is reacted after the hot metal is charged. A refining method characterized by charging into a container and refining without spraying a dephosphorizing agent onto the molten metal .
スクラップ及び粒径が５ｍｍ以下の粉体が含まれる第１の脱燐剤を反応容器に装入した後に、上記反応容器に溶銑を装入し、上記溶銑の装入後に第２の脱燐剤を反応容器に装入し、溶湯への脱燐剤の吹き付けを行なうことなく精錬を行なうことを特徴とする精錬方法。 In a refining method for performing dephosphorization or dephosphorization and decarburization without spraying a dephosphorizing agent to the molten metal,
After the first dephosphorizing agent containing scrap and powder having a particle size of 5 mm or less is charged into the reaction vessel, the hot metal is charged into the reaction vessel, and the second dephosphorizing agent is charged after the hot metal is charged. Is refined without charging the molten metal with a dephosphorizing agent .
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