JP2005133117A - Method for producing low phosphorus molten pig iron - Google Patents
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Abstract
Description
本発明は、転炉形式の炉を用いて溶銑脱燐処理を行うにあたって、スクラップの添加方法及び時期を制御することで、効率的に低燐溶銑を製造する方法に関する。 The present invention relates to a method for efficiently producing low phosphorus hot metal by controlling the method and timing of adding scrap when performing hot metal dephosphorization using a converter type furnace.
従来、溶銑段階で予備脱燐を行い、溶銑中の燐濃度をある程度除去してから転炉で脱炭吹錬を実施する製鋼方法が発展してきた。この予備脱燐処理では、溶銑中に石灰系煤溶剤とともに気体酸素・固体酸化鉄等の酸素源を添加するため、酸素源が溶銑中の燐と反応する以外にも炭素、珪素とも反応して溶銑温度が上昇する。脱燐反応は熱力学的に低温が有利であるため、処理後の溶銑温度は冷却材を添加することによって１３００℃前後に制御されている。鍋、トーピードでは、撹拌も弱く、ランスを溶銑中へ装入するため、冷却材としてスクラップを添加することが不可能であるが、転炉形式の炉では、底吹き撹拌が大きく、ランスも装入しないためスクラップを溶解することが可能である。 Conventionally, a steelmaking method has been developed in which preliminary dephosphorization is performed in the hot metal stage, and after removing the phosphorus concentration in the hot metal to some extent, decarburization blowing is performed in a converter. In this preliminary dephosphorization treatment, an oxygen source such as gaseous oxygen and solid iron oxide is added together with the lime-based soot solvent in the hot metal, so that the oxygen source reacts with carbon and silicon in addition to reacting with phosphorus in the hot metal. Hot metal temperature rises. Since the dephosphorization reaction is advantageous thermodynamically at a low temperature, the hot metal temperature after the treatment is controlled to around 1300 ° C. by adding a coolant. In the pan and torpedo, the stirring is weak and the lance is charged into the hot metal, so it is impossible to add scrap as a coolant. Since it does not enter, scrap can be melted.
転炉形式の炉を用いて溶銑脱燐処理を行うにあたり、スクラップを装入する方法として、「上下両吹き機能を有した２基の転炉形式の炉のうちの一方を脱燐炉、他方を脱炭炉として溶銑の精錬を行う製鋼方法であって、溶銑を前記脱燐炉へ注入した後、これに前記脱炭炉で発生した転炉滓を主成分とする精錬剤と幅が３０mm以下で厚さが１．５mm以下の軽量スクラップとを添加し、吹込みガス流量：０．０７Nm３/min・t以上で底吹きガス撹拌を行いつつ酸素ガスを上吹きして溶銑温度を１４００℃以下に保ちながら吹錬を行う…製鋼法」（特許文献１、特許請求の範囲参照）が開示されている。 When performing hot metal dephosphorization treatment using a converter type furnace, as a method of charging scrap, “one of two converter type furnaces having both upper and lower blowing functions is a dephosphorization furnace, the other Is a steelmaking method for refining hot metal using a decarburizing furnace, and after pouring hot metal into the dephosphorizing furnace, a refining agent mainly composed of a converter iron generated in the decarburizing furnace and a width of 30 mm In the following, lightweight scrap having a thickness of 1.5 mm or less is added, and the blowing gas flow rate: 0.07 Nm 3 / min · t or more, while stirring the bottom blowing gas, the oxygen gas is blown up and the hot metal temperature is 1400 A steelmaking method in which blowing is performed while maintaining the temperature at or below ° C. (see Patent Document 1 and claims) is disclosed.
また、「上下両吹き機能を有する転炉形式の炉に注銑した溶銑に脱燐剤を添加し、底吹ガス攪拌を行いつつ酸素ガスを上吹きして溶銑脱燐を行うに当たり、スクラップを溶解する方法として、まず脱燐剤の一部とスクラップと炭材を溶銑に添加して酸素を上吹きし、スクラップを溶解した後、残部の脱燐剤を添加して脱燐処理を行う方法が提案されている（特許文献２、特許請求の範囲参照）。 In addition, "Dephosphorizing agent is added to hot metal poured in a converter type furnace having both upper and lower blowing functions, and scrap is removed when hot metal dephosphorization is performed by blowing up oxygen gas while stirring the bottom blowing gas. As a melting method, first, a part of the dephosphorizing agent, scrap and carbonaceous material are added to the hot metal and oxygen is blown up, and after the scrap is melted, the remaining dephosphorizing agent is added and the dephosphorizing treatment is performed. Has been proposed (see Patent Document 2 and claims).
しかし、特許文献１に記載の方法では、スクラップのサイズが小さく、切断等の費用がかかるばかりでなく、固体酸素精錬剤を添加するため、その顕熱が大きく、溶銑配合率が最大でも９６．０％しか得られていないのが実情である。 However, in the method described in Patent Document 1, not only the scrap size is small and the cost for cutting and the like is high, but also a solid oxygen refining agent is added, so that the sensible heat is large and the hot metal blending ratio is 96. The fact is that only 0% is obtained.
また特許文献２に記載の方法では、工程がスクラップ溶解期と脱燐期に分かれるため、吹錬時間が非常に長くなり、生産性を阻害してしまう。 Further, in the method described in Patent Document 2, since the process is divided into a scrap melting period and a dephosphorization period, the blowing time becomes very long and the productivity is hindered.
このように、溶銑予備脱燐の処理を行う際に、スクラップの添加時期を吹錬開始前に一括で添加する従来の低燐溶銑の製造方法は、様々な問題を抱えていた。 Thus, when performing the hot metal preliminary dephosphorization process, the conventional low phosphorus hot metal manufacturing method in which the addition timing of scrap is added all at once before the start of blowing has had various problems.
そこで本発明は、上記従来の技術の問題点を鑑み、溶銑予備脱燐の処理を行う際に、スクラップの添加時期を制御することで、効率的に溶銑脱燐を行う脱燐処理方法を提案することを目的とする。 Therefore, in view of the above-mentioned problems of the conventional technique, the present invention proposes a dephosphorization processing method for efficiently performing hot metal dephosphorization by controlling the addition timing of scrap when performing the hot metal preliminary dephosphorization process. The purpose is to do.
本発明者は、転炉形式の炉を用いた実験で効率的に脱燐処理する方法を鋭意検討した。その結果、吹錬前の溶銑温度とその温度推移が処理後の溶銑中の[Ｐ]濃度に影響することを見出した。具体的には、吹錬前の溶銑温度が低い場合には処理後の溶銑中の[Ｐ]濃度が高くなる傾向がある。従来は、脱燐処理は燐の酸化反応であるため、低温の方が有利であるという考え方が一般的であったが、初期のスラグの造滓性は重要であり、その溶融性を確保するためには、処理温度を高く保つことが有効であることを知見した。そこで本発明者は、スクラップを吹錬開始前に予め装入するのではなく、吹錬開始後に炉上から添加する方法を考案した。 The present inventor has intensively studied a method for efficiently performing a dephosphorization treatment in an experiment using a converter type furnace. As a result, it was found that the hot metal temperature before blowing and the temperature transition affect the [P] concentration in the hot metal after treatment. Specifically, when the hot metal temperature before blowing is low, the [P] concentration in the hot metal after treatment tends to be high. Conventionally, since the dephosphorization process is an oxidation reaction of phosphorus, the idea that a low temperature is advantageous is generally used, but the initial slag structure is important and ensures its meltability. In order to achieve this, it has been found that keeping the treatment temperature high is effective. Therefore, the present inventor has devised a method of adding scrap from the furnace after the start of blowing rather than charging the scrap in advance before the start of blowing.
すなわち請求項１の発明は、上下両吹き機能を有する転炉形式の炉を用いて、炉内の溶銑に脱燐剤を添加する工程と、酸素ガスを上吹きしながら炉底からガスを流して溶銑を撹拌する吹錬工程と、を備える低燐溶銑の製造方法において、スクラップの全量もしくはその一部を、前記吹錬工程中に炉上から溶銑に添加することを特徴とする。 That is, the invention of claim 1 uses a converter type furnace having both upper and lower blowing functions, a step of adding a dephosphorizing agent to the hot metal in the furnace, and a gas is allowed to flow from the furnace bottom while blowing oxygen gas upward. A low-phosphorus hot metal production method comprising: a blowing step of stirring hot metal, wherein the entire amount of scrap or a part thereof is added to the hot metal from the furnace during the blowing step.
請求項２の発明は、請求項１に記載の低燐溶銑の製造方法において、吹錬工程中に添加するスクラップの添加時期を、吹錬工程期間の前半までとすることを特徴とする。 The invention of claim 2 is characterized in that, in the method for producing low phosphorus hot metal according to claim 1, the addition timing of the scrap added during the blowing process is set to the first half of the blowing process period.
請求項３の発明は、請求項１又は２に記載の低燐溶銑の製造方法において、前記脱燐剤としてフッ素化合物が含まれないことを特徴とする。なお、従来フッ素化合物としては、一般に蛍石等が使用されている。 According to a third aspect of the present invention, in the method for producing low phosphorus hot metal according to the first or second aspect, a fluorine compound is not included as the dephosphorizing agent. Conventionally, fluorite or the like is generally used as the fluorine compound.
請求項１の発明によれば、吹錬による溶銑の酸化反応に伴う温度上昇分に合わせて、スクラップを添加することができるため、低温での脱燐処理を回避でき、これにより処理後の溶銑中の[Ｐ]濃度を低減することができる。 According to the invention of claim 1, since scrap can be added in accordance with the temperature rise accompanying the oxidation reaction of hot metal by blowing, dephosphorization treatment at a low temperature can be avoided, and thereby the hot metal after treatment The [P] concentration in the medium can be reduced.
請求項２の発明のように、吹錬工程の前半までにスクラップの添加を終了すれば、未溶解がなくなる。 If the addition of scrap is completed by the first half of the blowing process as in the invention of claim 2, there is no undissolved state.
近年、環境問題の観点から脱燐剤としてのフッ素化合物、例えば蛍石はその使用が制約される。蛍石を使用しない場合、初期のスラグの溶融性の影響が大きく、処理前の溶銑温度が低いときに処理後の溶銑中の[Ｐ]濃度が高くなる傾向が特に著しい。本発明は脱燐剤としてのフッ素化合物を使用しない場合に特に有効である。 In recent years, the use of fluorine compounds such as fluorite as a dephosphorizing agent is restricted from the viewpoint of environmental problems. When fluorite is not used, the influence of the melting property of the initial slag is large, and when the hot metal temperature before the treatment is low, the tendency of the [P] concentration in the hot metal after the treatment to be high is particularly remarkable. The present invention is particularly effective when no fluorine compound is used as a dephosphorizing agent.
以下本発明の一実施形態を説明する。本発明の低燐溶銑の製造方法は、上下両吹き機能を有する転炉形式の炉を用いて、炉内の溶銑に脱燐剤を添加する工程と、酸素ガスを上吹きしながら炉底からガスを流して溶銑を撹拌する吹錬工程と、を備える。 An embodiment of the present invention will be described below. The method for producing low phosphorus hot metal of the present invention includes a step of adding a dephosphorizing agent to the hot metal in the furnace using a converter type furnace having both upper and lower blowing functions, and from the furnace bottom while blowing oxygen gas upward. And a blowing step of stirring the molten iron by flowing gas.
図１に示されるように、転炉形式の炉（転炉型容器とも呼ばれる）１とは、ランス２で上方から溶銑に酸素ガス６を吹き付ける一方、その炉底からＡｒ，Ｎ2，ＣＯ2，ＣＯ或いはＯ2ガスを吹き込んで溶銑４を補助的に攪拌する複合吹錬転炉を代表的なものとして挙げることができる。この実施形態では、炉底のノズル３から窒素ガス７を吹き込んでいる。脱燐剤５としては、石灰、後段の脱炭炉で発生した転炉滓、蛍石等を用いることができるが、この実施形態では石灰のみを用い、蛍石は使用しない。また脱燐処理の際、吹錬工程中に炉上からスクラップ８を添加する。
As shown in FIG. 1, a converter type furnace (also referred to as a converter type vessel) 1 is a lance 2 which blows oxygen gas 6 from above to hot metal, while Ar, N 2 , CO 2 from the furnace bottom. , CO or O 2 gas can be blown into the composite blow smelting converter in which the hot metal 4 is auxiliaryly stirred. In this embodiment, nitrogen gas 7 is blown from the nozzle 3 at the furnace bottom. As the
図２はスクラップの装入・添加時期の概念図を示す。図中（ａ）は従来一般的に行なわれている吹錬工程前にスクラップを装入する比較例を示し、図中（ｂ）は吹錬工程中にスクラップを添加する本発明例を示す。比較例では、炉に溶銑を注銑後、スクラップシュートからスクラップを装入し、その後吹錬を開始する。本発明では、炉に溶銑を注銑後、吹錬工程中、すなわち吹錬を開始した後に炉上からスクラップを添加する。 FIG. 2 shows a conceptual diagram of the charging / adding time of scrap. In the figure, (a) shows a comparative example in which scrap is charged before a conventional blowing process, and (b) shows an example of the present invention in which scrap is added during the blowing process. In the comparative example, after pouring hot metal into the furnace, the scrap is charged from the scrap chute, and then blowing is started. In the present invention, after pouring hot metal into the furnace, scrap is added from the furnace during the blowing process, that is, after the blowing is started.
本発明者は、転炉形式の炉を用いた実験で効率的に脱燐処理する方法を鋭意検討した。その結果、吹錬前の溶銑温度が低い場合には処理後の溶銑中の[Ｐ]濃度が高くなる傾向があり、特に近年環境問題からその使用が制限される蛍石を使用しない場合が特に著しいことが判明した。これは、転炉形式の炉では通常スクラップを吹錬前に入れるため、処理前温度が低い場合にはスクラップの顕熱でさらに溶銑温度が下がることが原因だと考えられる。従来は、脱燐処理は燐の酸化反応であるため、低温の方が有利であるという考え方が一般的であったが、初期のスラグの造滓性は重要であり、その溶融性を確保するためには、処理温度を高く保つことが有効である。特に脱燐剤として蛍石を使用しない場合には溶融性の影響は大きいと考えられる。そこで本発明では、スクラップを吹錬開始前に予め装入するのではなく、吹錬開始後に炉上から添加する。 The present inventor has intensively studied a method for efficiently performing a dephosphorization treatment in an experiment using a converter type furnace. As a result, when the hot metal temperature before blowing is low, the [P] concentration in the hot metal after treatment tends to be high, especially when fluorite that is restricted in recent years due to environmental problems is not used. It turned out to be remarkable. This is thought to be due to the fact that in the converter type furnace, scrap is usually put before blowing, and therefore, when the pre-treatment temperature is low, the hot metal temperature is further lowered by the sensible heat of the scrap. Conventionally, since the dephosphorization process is an oxidation reaction of phosphorus, the idea that a low temperature is advantageous is generally used, but the initial slag structure is important and ensures its meltability. For this purpose, it is effective to keep the processing temperature high. In particular, when fluorite is not used as a dephosphorizing agent, it is considered that the influence of meltability is great. Therefore, in the present invention, scrap is not charged in advance before the start of blowing, but is added from the furnace after the start of blowing.
本発明には、スクラップの一部を吹錬開始前に装入し、吹錬開始後に残りのスクラップを添加する場合も含まれる。装入・添加するスクラップ量は処理前温度（吹錬前の溶銑温度）が極端に低い場合には、炉上から全量添加するのが望ましいが、処理前温度がさほど低くない場合には、吹錬開始前に所要のスクラップの一部を装入し、吹錬開始後に残部のスクラップを添加してもよい。 The present invention includes a case where a part of the scrap is charged before the start of blowing and the remaining scrap is added after the start of blowing. If the pre-treatment temperature (hot metal temperature before blowing) is extremely low, it is desirable to add the entire amount from the furnace, but if the pre-treatment temperature is not so low, A part of the required scrap may be charged before the start of smelting, and the remaining scrap may be added after the start of smelting.
またスクラップを添加する時期を吹錬の後半まで引き延ばすと、スクラップの溶解時間が足りなくなり、未溶解のスクラップが生じることがわかっている。吹錬期間の前半の１／２内までに添加を終了すれば、未溶解がなくなることが確認された。未溶解が生じると鉄歩留まりが悪化するばかりでなく、スラグの排滓性、底吹きガスの閉鎖等のトラブルが発生するため操業上回避したい事項となる。 It has also been found that if the time for adding scrap is extended to the second half of blowing, the melting time of the scrap becomes insufficient and undissolved scrap is produced. It was confirmed that if the addition was completed within 1/2 of the first half of the blowing period, there was no undissolved. If undissolved, not only the iron yield deteriorates, but also troubles such as slag drainage and bottom blown gas closure occur, which is a matter to be avoided in operation.
本発明のように、脱燐処理の際にスクラップの添加時期を変更して、溶銑の温度制御をすることで、蛍石も使用しないで極めて優れた溶銑予備脱燐処理を行うことができる。 As in the present invention, by controlling the temperature of the hot metal by changing the addition time of scrap during the dephosphorization process, it is possible to perform an extremely excellent hot metal preliminary dephosphorization process without using fluorite.
高炉で出銑した溶銑を溶銑鍋内で脱珪処理し、機械撹拌を用いて溶銑鍋内で脱硫処理を施したあと、図１に示される３００ｔの転炉型容器内で脱珪処理を行った。上吹きランスを用いて酸素ガスを１．２〜１．５Nm3／(min・t)の速度で溶銑に吹き付けるとともに、炉底に埋め込まれたノズルを介して底吹きガスとして窒素ガスを０．０７〜０．１２Nm3／(min・t)の供給量で吹き込み、１０〜１２分間の吹錬時間で行った。なお、脱燐剤としては石灰のみを用い、処理前の溶銑［Ｓｉ］濃度に応じて、１４〜２１kg/t添加し、蛍石は使用しなかった。 The hot metal discharged in the blast furnace is desiliconized in the hot metal ladle, desulfurized in the hot metal ladle using mechanical stirring, and then desiliconized in the 300-ton converter type vessel shown in FIG. It was. Oxygen gas is blown onto the hot metal using a top blow lance at a rate of 1.2 to 1.5 Nm 3 / (min · t), and nitrogen gas is supplied as a bottom blown gas through a nozzle embedded in the furnace bottom. Blowing was performed at a supply rate of 07 to 0.12 Nm 3 / (min · t), and a blowing time of 10 to 12 minutes was performed. In addition, only lime was used as a dephosphorizing agent, 14 to 21 kg / t was added according to the hot metal [Si] concentration before treatment, and fluorite was not used.
また吹錬を開始した後に炉上からスクラップを添加した。添加するスクラップの一部を吹錬開始前に添加し、吹錬開始後に残りのスクラップを添加する場合の方法も実施した。 Also, after starting blowing, scrap was added from the furnace. A method of adding a part of the scrap to be added before the start of blowing and adding the remaining scrap after the start of blowing was also carried out.
各実施例の結果を、溶銑成分・温度の変化とともに表１に示す。スクラップを吹錬前に入れる比較例に比べて、吹錬中にスクラップの全量もしくは一部を添加する本発明例の方が脱燐率が高く、処理後の［Ｐ］濃度が低下した。処理前の溶銑温度が低い場合においても、吹錬後に全量スクラップを入れて温度制御することで所定の処理後［Ｐ］濃度が得られた。 The results of each example are shown in Table 1 together with the hot metal components and temperature changes. Compared to the comparative example in which scrap is put before blowing, the inventive example in which all or part of the scrap is added during blowing has a higher dephosphorization rate and the [P] concentration after the treatment is lowered. Even when the hot metal temperature before the treatment was low, the [P] concentration after the predetermined treatment was obtained by controlling the temperature by putting all the scrap after blowing.
今回、吹錬後に添加するスクラップの添加時期は、すべて吹錬時間の初期１／２までの期間に添加したものであり、脱燐終了後にはスクラップの溶け残りは確認されなかった。 This time, all the scraps added after blowing were added during the period up to the initial half of the blowing time, and no undissolved scrap was found after dephosphorization was completed.
Claims (3)
スクラップの全量もしくはその一部を、吹錬工程中に炉上から溶銑に添加することを特徴とする低燐溶銑の製造方法。 Using a converter-type furnace with both upper and lower blowing functions, adding a dephosphorizing agent to the hot metal in the furnace, and blowing process for stirring the hot metal by flowing gas from the furnace bottom while blowing up oxygen gas In a method for producing low phosphorus hot metal comprising:
A method for producing low phosphorus hot metal, characterized in that the entire amount of scrap or a part thereof is added to the hot metal from the furnace during the blowing process.
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| JP2003367888A JP4411934B2 (en) | 2003-10-28 | 2003-10-28 | Method for producing low phosphorus hot metal |
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| JP2003367888A JP4411934B2 (en) | 2003-10-28 | 2003-10-28 | Method for producing low phosphorus hot metal |
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| JP4411934B2 JP4411934B2 (en) | 2010-02-10 |
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| JPWO2022163200A1 (en) * | 2021-01-26 | 2022-08-04 | ||
| JPWO2022163202A1 (en) * | 2021-01-26 | 2022-08-04 | ||
| WO2022163219A1 (en) | 2021-01-26 | 2022-08-04 | Ｊｆｅスチール株式会社 | Method for refining molten iron |
| RU2820427C1 (en) * | 2021-01-26 | 2024-06-03 | ДжФЕ СТИЛ КОРПОРЕЙШН | Liquid iron refining method |
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| WO2022163219A1 (en) | 2021-01-26 | 2022-08-04 | Ｊｆｅスチール株式会社 | Method for refining molten iron |
| WO2022163200A1 (en) | 2021-01-26 | 2022-08-04 | Ｊｆｅスチール株式会社 | Method for refining molten iron |
| WO2022163202A1 (en) | 2021-01-26 | 2022-08-04 | Ｊｆｅスチール株式会社 | Converter steel making method |
| JP7211557B2 (en) | 2021-01-26 | 2023-01-24 | Ｊｆｅスチール株式会社 | Molten iron smelting method |
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| KR20230133976A (en) | 2021-01-26 | 2023-09-19 | 제이에프이 스틸 가부시키가이샤 | Converter steelmaking method |
| KR20230133978A (en) | 2021-01-26 | 2023-09-19 | 제이에프이 스틸 가부시키가이샤 | Method of refining molten iron |
| KR20230133977A (en) | 2021-01-26 | 2023-09-19 | 제이에프이 스틸 가부시키가이샤 | Method of refining molten iron |
| RU2820427C1 (en) * | 2021-01-26 | 2024-06-03 | ДжФЕ СТИЛ КОРПОРЕЙШН | Liquid iron refining method |
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| Publication number | Publication date |
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| JP4411934B2 (en) | 2010-02-10 |
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