JP2001049320A - Production of iron and steel using high phosphorus ore as raw material - Google Patents

Production of iron and steel using high phosphorus ore as raw material

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Publication number
JP2001049320A
JP2001049320A JP11228983A JP22898399A JP2001049320A JP 2001049320 A JP2001049320 A JP 2001049320A JP 11228983 A JP11228983 A JP 11228983A JP 22898399 A JP22898399 A JP 22898399A JP 2001049320 A JP2001049320 A JP 2001049320A
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JP
Japan
Prior art keywords
hot metal
slag
dephosphorization
treatment
amount
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
Application number
JP11228983A
Other languages
Japanese (ja)
Other versions
JP3829543B2 (en
Inventor
Yoshiteru Kikuchi
良輝 菊地
Eiju Matsuno
英寿 松野
Hiroshi Shimizu
宏 清水
Atsushi Watanabe
敦 渡辺
Hideshige Tanaka
秀栄 田中
Hidetoshi Noda
英俊 野田
Koichi Ichikawa
孝一 市川
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
JFE Engineering Corp
Original Assignee
NKK Corp
Nippon Kokan Ltd
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Publication date
Application filed by NKK Corp, Nippon Kokan Ltd filed Critical NKK Corp
Priority to JP22898399A priority Critical patent/JP3829543B2/en
Publication of JP2001049320A publication Critical patent/JP2001049320A/en
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Publication of JP3829543B2 publication Critical patent/JP3829543B2/en
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Expired - Fee Related legal-status Critical Current

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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Abstract

PROBLEM TO BE SOLVED: To provide an iron and steel producing method, by which dephosphorizing treatment can efficiently be executed to molten iron obtd. by using high phosphorus ore as a raw material and the adding quantity of flux and the produced quantity of slag, etc., can be reduced as much as possible. SOLUTION: In the dephosphorizing method of the molten iron having high phosphorus concn., it is extremely effective that the silicon concn. in the molten iron is beforehand reduced to the achievement of high dephosphorizing efficiency and the lowering of the produced slag quantity. This method consists of at least a process for charging the iron ore having >=0.06 wt.% phosphorus concn. as a part or the whole of the iron source into a blast furnace, a process for obtaining molten iron having <=0.20 wt.% silicon concn. by executing a desiliconizing treatment at iron-tapping from the blast furnace or after iron- tapping from the blast furnace, a process for executing the dephosphorizing treatment to the low silicon molten iron undergone the above process and a process for executing a decarburizing treatment to the molten iron undergone the dephosphorizing treatment process.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【発明の属する技術分野】本発明は、省資源・省エネル
ギーで、且つスラグなどの発生物の量も極力少なくでき
る環境に優しい鉄鋼製造方法、詳細には、従来では鉄鋼
製造に使用しにくかった燐濃度が高い鉄鉱石を有効利用
することにより省資源に役立ち、しかも溶銑の効率的な
精錬処理が可能で、且つ媒溶剤の添加量やスラグなどの
発生物の量も極力低減できる鉄鋼製造方法に関するもの
である。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an environment-friendly method for producing iron and steel, which saves resources and energy and minimizes the amount of slag and the like, and in particular, phosphorus which has been conventionally difficult to use in steel production. The present invention relates to a method for producing steel capable of conserving resources by effectively utilizing iron ore having a high concentration, enabling efficient refining of hot metal, and reducing the amount of a medium solvent added and the amount of generated products such as slag as much as possible. Things.

【０００２】[0002]

【従来の技術】高炉で得られた溶銑から鋼材を製造する
には、製鋼精錬過程において溶銑に含まれる不純物成分
を所定濃度まで低減するとともに、必要な成分を添加し
て鋼材として要求される成分組成に調整することが必要
である。溶銑に含まれる不純物成分としては、溶銑に４
ｗｔ％以上含まれる炭素のほか、燐、硫黄などがあり、
また、鋼材の要求成分としては強度や靭性を高めるマン
ガン、珪素などがある。2. Description of the Related Art In order to manufacture steel from hot metal obtained in a blast furnace, it is necessary to reduce the impurity components contained in the hot metal to a predetermined concentration in the steelmaking refining process and to add necessary components to the components required as steel. It is necessary to adjust the composition. As an impurity component contained in hot metal, 4
In addition to carbon contained by wt% or more, there are phosphorus, sulfur, etc.
In addition, required components of the steel material include manganese, silicon, and the like that increase strength and toughness.

【０００３】溶銑から燐や炭素を除くためには、溶銑を
脱燐スラグと反応させたり、大量の酸素を添加して酸化
反応を進行させる方法が採られるが、転炉を用いて炭素
・燐を同時に除去していた従来の方法に対し、最近では
溶銑段階で燐だけを事前に除去（溶銑予備脱燐処理）し
た後、転炉脱炭吹錬を行う方法が普及しつつある。ま
た、この転炉脱炭吹錬では、高価なマンガン合金鉄の使
用量を削減するために、マンガン鉱石や高マンガンスラ
グなどのマンガン源が添加される。[0003] In order to remove phosphorus and carbon from the hot metal, a method of reacting the hot metal with dephosphorized slag or adding a large amount of oxygen to promote the oxidation reaction is adopted. In contrast to the conventional method of removing phosphorus simultaneously, a method of removing only phosphorus in advance in the hot metal stage (preliminary hot metal dephosphorization treatment) and then performing decarburization blowing of a converter is becoming widespread. In this converter decarburization blowing, a manganese source such as manganese ore and high manganese slag is added in order to reduce the amount of expensive manganese alloy iron used.

【０００４】このように溶銑予備脱燐処理を行った後、
転炉脱炭吹錬を行う方法では、転炉吹錬において脱燐の
ために必要であったスラグの量を減らすことが可能にな
り、その結果、転炉吹錬終了時点でスラグからのマンガ
ン還元率を高め、出鋼中または出鋼後に添加されるマン
ガン合金鉄の使用量を削減することできる。[0004] After performing the hot metal preliminary dephosphorization treatment in this way,
In the converter decarburization blowing method, it is possible to reduce the amount of slag required for dephosphorization in the converter blowing, and as a result, manganese from the slag at the end of the converter blowing The reduction rate can be increased, and the amount of manganese alloy iron added during or after tapping can be reduced.

【０００５】溶銑予備脱燐処理は、溶銑鍋や転炉のほ
か、トーピード設備などでも行われ、主な媒溶剤である
石灰に加え、脱燐反応の促進に必要な酸素源として鉄鉱
石やスケールなどの固体酸素源や気体酸素が添加され
る。この方法では、脱燐反応上有利な低温処理が可能な
こともあって元々少ないスラグ量で脱燐処理が可能であ
るが、最近の環境保護対策の観点から、この溶銑予備脱
燐処理や転炉脱炭吹錬で発生するスラグをさらに極限ま
で削減することが求められている。[0005] Preliminary hot metal dephosphorization is performed not only in a hot metal ladle and a converter, but also in a torpedo facility. In addition to lime, which is the main solvent, iron ore and scale are used as oxygen sources necessary for promoting the dephosphorization reaction. A solid oxygen source, such as, or gaseous oxygen is added. This method enables low-temperature treatment, which is advantageous for the dephosphorization reaction, to enable dephosphorization with a small amount of slag.However, from the viewpoint of recent environmental protection measures, this hot metal preliminary dephosphorization and It is required to further reduce the slag generated by furnace decarburization blowing to the utmost.

【０００６】[0006]

【発明が解決しようとする課題】上記のような脱燐及び
脱炭を効率的に行える方法は、現在の高炉−転炉法の主
流となっているが、鋼材の低燐化とスラグ発生量の削減
という要求に対しては、高炉で使用される原料の厳選を
基盤とせざるを得ないのが現状である。特に、鋼材の低
燐化に関しては、従来から高炉による溶銑製造の主原料
である鉄鉱石は低い燐濃度に管理されている。すなわ
ち、鉱山で採掘され鉄鋼製造工場へ運ばれる鉄鉱石の多
くは燐濃度が０．０６ｗｔ％未満のものであり、これを
超えるような燐濃度のものは効率的な脱燐処理が困難で
あるなどの理由から殆ど有効利用されていないのが現状
である。The above-mentioned method of efficiently performing dephosphorization and decarburization is the mainstream of the current blast furnace-converter method. At present, the demand for reduction of waste must be based on careful selection of raw materials used in blast furnaces. In particular, regarding the reduction of phosphorus in steel materials, iron ore, which is a main raw material for hot metal production by a blast furnace, has been conventionally controlled to a low phosphorus concentration. That is, most of the iron ore mined in the mine and transported to the steel manufacturing plant has a phosphorus concentration of less than 0.06 wt%, and a phosphorus concentration exceeding this is difficult to efficiently remove phosphorus. At present, it is hardly used effectively for such reasons.

【０００７】このため鉄鉱石の鉱山においては低燐濃度
の鉱石が優先的に採掘されているのが実状で、採掘のた
めのエネルギーや労力などの増加や将来の資源枯渇が心
配されており、原料資源の活用の観点からも高燐濃度鉱
石の大量利用を可能とする鉄鋼製造法の確立が大きな課
題となっている。したがって本発明の目的は、このよう
な従来技術の課題を解決し、高炉用鉄源として高燐濃度
の鉄鉱石を大量に利用することができる鉄鋼製造方法で
あって、この高燐濃度の鉄鉱石を原料として得られた溶
銑を効率的に脱燐処理することができ、しかも媒溶剤の
添加量やスラグなどの発生物の量も極力低減できる鉄鋼
製造方法を提供することにある。For this reason, in iron ore mines, it is a fact that ore with a low phosphorus concentration is preferentially mined, and there is a concern that increases in energy and labor for mining and depletion of resources in the future will occur. From the viewpoint of utilization of raw material resources, establishment of a steel production method that enables large-scale utilization of high-phosphorus-concentration ores has become a major issue. Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art and to provide a steel production method capable of utilizing a large amount of iron ore having a high phosphorus concentration as an iron source for a blast furnace. It is an object of the present invention to provide a method for producing steel capable of efficiently dephosphorizing hot metal obtained from stone as a raw material and further reducing the amount of a solvent added and the amount of generated products such as slag as much as possible.

【０００８】[0008]

【課題を解決するための手段】本発明は、高炉において
高燐濃度の鉄鉱石を用いて得られた溶銑を、精錬過程に
おいて脱燐効率を極限まで高めることができる方法を提
供しようとするものである。このような課題に対して
は、脱燐の反応原理だけでなく、脱燐スラグ量を極力減
少させるなどの一貫プロセスにおける条件も考慮するこ
とが重要である。SUMMARY OF THE INVENTION The present invention aims to provide a method for improving the efficiency of dephosphorization of hot metal obtained by using iron ore having a high phosphorus concentration in a blast furnace in a smelting process. It is. For such a problem, it is important to consider not only the reaction principle of dephosphorization but also the conditions in an integrated process such as minimizing the amount of dephosphorized slag.

【０００９】溶銑の脱燐処理は、基本的には溶銑中の燐
を酸化させることにより生成する燐酸（酸性酸化物）を
塩基性の媒溶剤で固定することによりなされる。このた
め脱燐処理では、主として気体酸素や酸化鉄などの酸素
源により高い酸素ポテンシャルが維持され、且つ生成し
た燐酸を安定化させ得る塩基度の高いスラグが得られる
ようにする必要があり、特に後者に関しては、酸化カル
シウム（ＣａＯ）源として通常用いられる石灰の投入量
が制御される。一方、高燐濃度の鉄鉱石を用いて得られ
た溶銑の脱燐処理では、脱燐反応で生成する燐酸の量が
増加し、このため一般的には使用する石灰及び生成する
スラグ量は増加する。すなわち、燐酸は珪酸と同様に酸
性酸化物であるため、塩基性酸化物の必要量が増えるこ
とになる。[0009] The dephosphorization of the hot metal is basically performed by fixing phosphoric acid (acid oxide) generated by oxidizing phosphorus in the hot metal with a basic medium solvent. Therefore, in the dephosphorization treatment, it is necessary to maintain a high oxygen potential mainly by an oxygen source such as gaseous oxygen or iron oxide, and to obtain a highly basic slag capable of stabilizing generated phosphoric acid. For the latter, the input of lime, which is commonly used as a source of calcium oxide (CaO), is controlled. On the other hand, in the dephosphorization treatment of hot metal obtained using iron ore with a high phosphorus concentration, the amount of phosphoric acid generated in the dephosphorization reaction increases, and therefore the amount of lime used and the amount of slag generated generally increase. I do. That is, since phosphoric acid is an acidic oxide like silicic acid, the required amount of basic oxide increases.

【００１０】本発明者らは、溶銑中の珪素濃度を十分に
低減させることにより少ない石灰量で高い塩基度を確保
できるとともに、発生するスラグ量も少なくすることが
でき、しかも、高燐濃度の鉄鉱石を使用した場合には生
成する燐酸が多くなるためスラグ中の珪酸はほとんど不
要である、という観点から高燐濃度溶銑の脱燐処理法に
ついて検討を進めた。その結果、高燐濃度溶銑の脱燐処
理では事前に溶銑中の珪素濃度を低減させておくこと、
さらに好ましくは脱燐反応による燐酸の生成量に応じて
珪酸の生成量や石灰の添加量を制御することが高脱燐効
率の達成とスラグ生成量の低減化に極めて有効であるこ
とを明らかにした。The inventors of the present invention can secure a high basicity with a small amount of lime by reducing the silicon concentration in the hot metal sufficiently, can also reduce the amount of slag generated, and have a high phosphorus concentration. From the viewpoint that the amount of phosphoric acid generated when iron ore is used is large, and silicic acid in slag is almost unnecessary, the study on dephosphorization of hot metal with high phosphorus concentration has been studied. As a result, in the dephosphorization treatment of hot metal with high phosphorus concentration, the silicon concentration in the hot metal must be reduced in advance,
More preferably, it is clear that controlling the amount of silicic acid and the amount of lime added according to the amount of phosphoric acid generated by the dephosphorization reaction is extremely effective in achieving high dephosphorization efficiency and reducing the amount of slag generated. did.

【００１１】すなわち本発明は、以下のような特徴を有
する鉄鋼製造方法である。 [1] 高炉内に鉄源の一部又は全部として燐濃度が０．０
６ｗｔ％以上の鉄鉱石を装入する工程と、高炉からの出
銑ままで又は高炉出銑後の脱珪処理を経ることで珪素濃
度が０．２０ｗｔ％以下の溶銑を得る工程と、該工程を
経た低珪素溶銑を脱燐処理する工程と、該脱燐処理工程
を経た溶銑を脱炭処理する工程とを、少なくとも有する
ことを特徴とする高燐鉱石を原料とする鉄鋼製造方法。That is, the present invention is a method for producing steel having the following features. [1] Phosphorus concentration of 0.0
A step of charging 6% by weight or more of iron ore, a step of obtaining molten iron having a silicon concentration of 0.20% by weight or less through tapping from a blast furnace or a desiliconization process after tapping from a blast furnace, and A method for producing steel using high-phosphorus ore as a raw material, comprising at least a step of dephosphorizing low-silicon hot metal that has passed through, and a step of decarburizing the hot metal that has passed through the dephosphorization step.

【００１２】[2] 上記[1]の鉄鋼製造方法において、高
炉から出銑された溶銑の燐濃度［Ｐ］（ｗｔ％）と脱燐
処理前の溶銑の珪素濃度［Ｓｉ］（ｗｔ％）が下式を満
足することを特徴とする高燐鉱石を原料とする鉄鋼製造
方法。 ０．１０≦［Ｐ］＋０．７・［Ｓｉ］≦０．５０ ［Ｐ］≧０．１０[2] In the method for producing steel according to the above [1], the phosphorus concentration [P] (wt%) of the hot metal tapped from the blast furnace and the silicon concentration [Si] (wt%) of the hot metal before the dephosphorization treatment are performed. Satisfies the following formula: A method for producing steel using high phosphate rock as a raw material. 0.10 ≦ [P] + 0.7 · [Si] ≦ 0.50 [P] ≧ 0.10

【００１３】[3] 上記[1]又は[2]の鉄鋼製造方法におい
て、溶銑の脱燐処理に用いられる石灰の溶銑トン当たり
の添加量Ｗｃ（ｋｇ）と、高炉から出銑された溶銑の燐
濃度［Ｐ］（ｗｔ％）と、脱燐処理前の溶銑の珪素濃度
［Ｓｉ］（ｗｔ％）が下式を満足することを特徴とする
高燐鉱石を原料とする鉄鋼製造方法。 ３０≦Ｗｃ／（［Ｐ］＋０．７・［Ｓｉ］）≦１５０ ［Ｐ］≧０．１０[3] In the method for producing steel according to the above [1] or [2], the addition amount Wc (kg) of lime used for dephosphorizing hot metal per ton of hot metal and the hot metal discharged from the blast furnace A method for producing steel using high phosphorous ore as a raw material, wherein a phosphorus concentration [P] (wt%) and a silicon concentration [Si] (wt%) of hot metal before dephosphorization treatment satisfy the following formulas. 30 ≦ Wc / ([P] + 0.7 · [Si]) ≦ 150 [P] ≧ 0.10

【００１４】[4] 上記[1]〜[3]のいずれかの鉄鋼製造方
法において、溶銑の脱燐処理工程で発生する溶銑トン当
たりのスラグ量Ｗｓ（ｋｇ）と、高炉から出銑された溶
銑の燐濃度［Ｐ］（ｗｔ％）と、脱燐処理前の溶銑の珪
素濃度［Ｓｉ］（ｗｔ％）が下式を満足することを特徴
とする高燐鉱石を原料とする鉄鋼製造方法。 ４０≦Ｗｓ／（［Ｐ］＋０．７・［Ｓｉ］）≦２５０ ［Ｐ］≧０．１０[4] In the method for producing steel according to any one of the above [1] to [3], the amount of slag Ws (kg) per ton of hot metal generated in the dephosphorization step of hot metal, and A method for producing steel from high phosphorous ore, characterized in that the phosphorus concentration [P] (wt%) of the hot metal and the silicon concentration [Si] (wt%) of the hot metal before the dephosphorization treatment satisfy the following formula: . 40 ≦ Ws / ([P] + 0.7 · [Si]) ≦ 250 [P] ≧ 0.10.

【００１５】[5] 上記[1]又は[2]の鉄鋼製造方法におい
て、脱炭処理工程で生じたスラグの一部又は全部を脱燐
処理の媒溶剤として用いることを特徴とする高燐鉱石を
原料とする鉄鋼製造方法。 [6] 上記[5]の鉄鋼製造方法において、溶銑の脱燐処理
に用いられる石灰の溶銑トン当たりの添加量Ｗｃ（ｋ
ｇ）と、高炉から出銑された溶銑の燐濃度［Ｐ］（ｗｔ
％）と、脱燐処理前の溶銑の珪素濃度［Ｓｉ］（ｗｔ
％）が下式を満足することを特徴とする高燐鉱石を原料
とする鉄鋼製造方法。 Ｗｃ／（［Ｐ］＋０．７・［Ｓｉ］）≦１５０ ［Ｐ］≧０．１０[5] The method for producing steel according to the above [1] or [2], wherein a part or all of the slag generated in the decarburizing step is used as a solvent for the dephosphorizing step. A method for producing steel from raw materials. [6] In the steel manufacturing method of the above [5], the addition amount of lime used per ton of hot metal Wc (k
g) and the phosphorus concentration [P] (wt) of the hot metal tapped from the blast furnace.
%) And the silicon concentration [Si] (wt
%) Which satisfies the following formula: Wc / ([P] + 0.7 · [Si]) ≦ 150 [P] ≧ 0.10

【００１６】[7] 上記[5]又は[6]の鉄鋼製造方法におい
て、溶銑の脱燐処理工程で新たに発生する溶銑トン当た
りのスラグ量Ｗｓ（ｋｇ）と、高炉から出銑された溶銑
の燐濃度［Ｐ］（ｗｔ％）と、脱燐処理前の溶銑の珪素
濃度［Ｓｉ］（ｗｔ％）が下式を満足することを特徴と
する高燐鉱石を原料とする鉄鋼製造方法。 Ｗｓ／（［Ｐ］＋０．７・［Ｓｉ］）≦２５０ ［Ｐ］≧０．１０[7] In the method for producing steel according to the above [5] or [6], the amount of slag Ws (kg) per ton of hot metal newly generated in the process of dephosphorizing hot metal and the hot metal discharged from the blast furnace A method for producing steel using high phosphorous ore, characterized in that the phosphorus concentration [P] (wt%) and the silicon concentration [Si] (wt%) of the hot metal before the dephosphorization treatment satisfy the following expression. Ws / ([P] + 0.7 · [Si]) ≦ 250 [P] ≧ 0.10

【００１７】[0017]

【発明の実施の形態】従来の高炉操業で鉄源として用い
られている鉄鉱石は、通常、燐濃度がおおよそ０．０４
〜０．０５ｗｔ％程度のものが主体となっているが、本
発明法では高炉に装入する鉄鉱石の一部又は全部として
燐濃度が０．０６ｗｔ％以上のものを用いる。高炉で
は、鉄鉱石を塊鉱石または粉鉱石のまま若しくは焼結法
などで粉鉱石を塊状にしてから用いることができる。DETAILED DESCRIPTION OF THE INVENTION Iron ore used as an iron source in a conventional blast furnace operation usually has a phosphorus concentration of about 0.04.
In general, the iron ore charged into the blast furnace has a phosphorus concentration of 0.06 wt% or more as a part or all of the iron ore charged in the blast furnace. In the blast furnace, the iron ore can be used as a lump ore or a fine ore or after a fine ore is made into a lump by a sintering method or the like.

【００１８】本発明では、上記のように高炉の鉄源の少
なくとも一部として高燐鉱石を使用した上で、高炉から
の出銑ままで又は高炉出銑後の脱珪処理を経ることで珪
素濃度が０．２０ｗｔ％以下、好ましくは０．１０ｗｔ
％以下の溶銑を得るものであり、このために原料の調
整、高炉操業条件の適正化、高炉出銑後の脱硅素処理の
いずれか若しくは２つ以上の組み合わせによって、溶銑
の珪素濃度の低減化を図る。溶銑の珪素濃度が脱燐処理
前の段階で０．２０ｗｔ％を超えると、本発明が狙いと
する高燐溶銑の脱燐処理における脱燐効率の向上と媒溶
剤及びスラグ量の低減化が達成できない。In the present invention, as described above, high phosphorus ore is used as at least a part of the iron source of the blast furnace, and then silicon is removed while tapping from the blast furnace or through desiliconization after tapping from the blast furnace. The concentration is 0.20 wt% or less, preferably 0.10 wt%
% Or less of the hot metal. For this purpose, the silicon concentration of the hot metal can be reduced by adjusting the raw materials, optimizing the operating conditions of the blast furnace, or removing silicon from the blast furnace by tapping or by combining two or more of them. Plan. When the silicon concentration of the hot metal exceeds 0.20 wt% before the dephosphorization treatment, the present invention aims to improve the dephosphorization efficiency and reduce the amount of solvent and slag in the dephosphorization treatment of the high-phosphorus hot metal. Can not.

【００１９】高炉において珪素濃度の低い溶銑を製造す
る方法としては、原料の予備処理などによって高炉への
珪酸分の全装入量を低減したり、高炉内での珪酸還元反
応を抑制するために低温操業やコークスの偏在装入など
を行うことが可能である。また、高炉から出銑された溶
銑には通常脱珪処理が実施されるが、高炉から出銑され
た溶銑の珪素濃度が０．２０ｗｔ％を超える場合には、
この脱珪処理工程で溶銑の珪素濃度を０．２０ｗｔ％以
下まで低減させる。As a method for producing hot metal having a low silicon concentration in a blast furnace, a method of preliminarily processing raw materials to reduce the total amount of silicic acid charged into the blast furnace or to suppress a silicate reduction reaction in the blast furnace is used. It is possible to perform low-temperature operation and uneven charging of coke. In addition, the hot metal discharged from the blast furnace is usually desiliconized. However, when the silicon concentration of the hot metal discharged from the blast furnace exceeds 0.20 wt%,
In this desiliconization treatment step, the silicon concentration of the hot metal is reduced to 0.20 wt% or less.

【００２０】一般に、高炉から出銑された溶銑は鋳床を
経由して溶銑鍋などの容器に注湯及び貯留されるが、前
記脱珪処理は鋳床での脱珪、容器内での脱珪のいずれ
か、若しくはその両方で実施してよい。容器内での脱珪
処理は溶銑鍋や装入鍋などの取鍋だけでなく、媒溶剤や
酸素源などの副原料の供給機能（さらに好ましくは、溶
銑の撹拌機能）を備えたものであれば如何なる形式の容
器で行ってよく、例えば、溶銑鍋と同様の溶銑搬送容器
であるトーピード（混銑車）でも行ってもよいし、転炉
型容器で行ってもよい。また、脱珪専用の容器で脱珪処
理を行ってもよい。Generally, hot metal discharged from a blast furnace is poured and stored in a container such as a hot metal pot via a casting bed. The desiliconization treatment includes desiliconization in the casting bed and desiliconization in the vessel. It may be implemented with either or both of the silicon. The desiliconization treatment in the vessel is not only a ladle such as a hot metal ladle or a charging pan, but also a function having a function of supplying auxiliary materials such as a medium solvent and an oxygen source (more preferably, a function of agitating the hot metal). It may be carried out in any type of vessel, for example, in a torpedo (mixed iron wheel), which is a hot metal transfer vessel similar to a hot metal pot, or in a converter type vessel. Further, the desiliconization treatment may be performed in a container dedicated to desiliconization.

【００２１】脱珪処理では脱珪剤として酸素源が添加さ
れ、また、必要に応じて媒溶剤として焼石灰などのＣａ
Ｏ分が添加され、スラグの塩基度が調整される。酸素源
としては、固体酸素源（例えば、鉄鉱石やミルスケール
などの酸化鉄）または気体酸素（酸素ガス又は酸素含有
ガス）のいずれを用いてもよく、また両者を併用しても
よい。酸素源の添加は、溶湯流（鋳床や鋳床から溶銑鍋
などの容器への溶銑流）または溶湯浴面上への酸素源の
上置きや浴中への吹き込みにより行うが、さらにガス撹
拌などを付与したり、焼石灰などのＣａＯ分を添加して
スラグの塩基度を調整したりして、スラグ中に残存する
脱珪剤（酸化鉄などの酸素源）を極力少なくすることで
脱珪効率を高めることができる。In the desiliconization treatment, an oxygen source is added as a desiliconizing agent, and if necessary, a medium such as calcined lime is used as a solvent.
O content is added to adjust the basicity of the slag. As the oxygen source, either a solid oxygen source (for example, iron oxide such as iron ore or mill scale) or gaseous oxygen (oxygen gas or oxygen-containing gas) may be used, or both may be used in combination. The oxygen source is added by the molten metal flow (hot metal flow from the casting bed or the casting bed to a container such as a hot metal ladle) or by placing the oxygen source on the molten metal bath or blowing it into the bath. By adding CaO such as calcined lime to adjust the basicity of the slag to reduce the amount of desiliconizing agent (oxygen source such as iron oxide) remaining in the slag as much as possible. Efficiency can be increased.

【００２２】上述したように脱珪処理では溶銑をガス撹
拌等により十分に撹拌することが、脱珪効率を高める上
で有効である。この点、取鍋等の容器内で行う脱珪処理
は、その溶銑保持形状のために溶銑を十分に撹拌できる
ため、他の方法（例えば、鋳床での脱珪処理）よりも効
率が良い。したがって、特に優れた脱珪効率を得るため
には、取鍋などの容器内での脱珪処理を実施するか、或
いは鋳床脱珪を実施した後、容器内での脱珪処理を実施
するのが好ましい。As described above, in the desiliconization treatment, it is effective to sufficiently stir the molten iron by gas stirring or the like in order to increase the desiliconization efficiency. In this regard, desiliconization performed in a container such as a ladle is more efficient than other methods (e.g., desiliconization in a cast bed) because the hot metal can be sufficiently stirred due to its shape. . Therefore, in order to obtain a particularly excellent desiliconization efficiency, the desiliconization process is performed in a container such as a ladle, or the desiliconization process is performed in the container after the cast floor desiliconization is performed. Is preferred.

【００２３】図１は、溶銑鍋１を用いた脱珪処理状況の
一例を模式的に示しており、この例では溶銑鍋１内に送
酸ランス２を通じて気体酸素（酸素ガスまたは酸素含有
ガス）が吹き込まれるとともに、浸漬ランス３を通じて
撹拌ガスや石灰粉等の媒溶剤が溶銑中に吹き込まれ、さ
らに必要に応じて固体原料（例えば、焼結粉やミルスケ
ール等の固体酸素源）が鍋上方の原料投入装置４から上
置き装入できるようになっている。FIG. 1 schematically shows an example of a desiliconization process using a hot metal ladle 1. In this example, gaseous oxygen (oxygen gas or oxygen-containing gas) is passed through an acid lance 2 into the hot metal ladle 1. And a solvent medium such as stirring gas or lime powder is blown into the hot metal through the immersion lance 3, and further, if necessary, a solid material (for example, a solid oxygen source such as a sintered powder or a mill scale) is placed above the pot. From the raw material input device 4 of the above.

【００２４】このようにして得られた珪素濃度が０．２
０ｗｔ％以下の低珪素溶銑は脱燐処理工程で脱燐処理さ
れる。脱燐処理される溶銑は低珪素濃度であるため、ス
ラグ塩基度（ＣａＯ／ＳｉＯ２）を容易に高めることが
でき、脱燐能が高いスラグを生成できるとともに、スラ
グ量を極力少なくして精錬を行うことができる。スラグ
の塩基度を高めるため、事前に脱珪処理した際の脱珪ス
ラグなどの混入は極力抑制することが好ましく、このた
め機械式排滓装置や手作業などにより前工程で生じたス
ラグを分離した溶銑を脱燐処理する。The silicon concentration thus obtained is 0.2
The low silicon hot metal of 0 wt% or less is dephosphorized in the dephosphorization step. Since the hot metal to be dephosphorized has a low silicon concentration, slag basicity (CaO / SiO 2 ) can be easily increased, slag having high dephosphorization ability can be produced, and slag amount is reduced as much as possible for refining. It can be performed. In order to increase the basicity of the slag, it is preferable to minimize the incorporation of desiliconized slag during the desiliconization treatment in advance, so the slag generated in the previous process is separated by a mechanical waste disposal device or manual work. The hot metal thus dephosphorized is treated.

【００２５】本発明法においては、脱燐処理される高燐
溶銑は珪素濃度が０．２０ｗｔ％以下である必要がある
が、溶銑の珪素濃度が低過ぎると石灰（ＣａＯ）の滓化
に支障を来すおそれがあり、したがって、高炉から出銑
された溶銑の燐濃度に対して脱燐処理前の珪素濃度には
好ましい範囲が存在する。すなわち、高炉から出銑され
た溶銑の燐濃度［Ｐ］（ｗｔ％）と脱燐処理前の溶銑の
珪素濃度［Ｓｉ］（ｗｔ％）は下式を満足することが好
ましい。 ０．１０≦［Ｐ］＋０．７・［Ｓｉ］≦０．５０ また、高炉から出銑された溶銑の燐濃度［Ｐ］（ｗｔ
％）は０．１０ｗｔ％以上とすることが好ましい。In the method of the present invention, the high-phosphorus hot metal to be dephosphorized must have a silicon concentration of not more than 0.20% by weight. However, if the silicon concentration of the hot metal is too low, slagging of lime (CaO) is hindered. Therefore, there is a preferable range of the silicon concentration before the dephosphorization treatment with respect to the phosphorus concentration of the hot metal tapped from the blast furnace. That is, it is preferable that the phosphorus concentration [P] (wt%) of the hot metal spouted from the blast furnace and the silicon concentration [Si] (wt%) of the hot metal before the dephosphorization treatment satisfy the following expressions. 0.10 ≦ [P] + 0.7 · [Si] ≦ 0.50 Further, the phosphorus concentration [P] (wt.)
%) Is preferably 0.10 wt% or more.

【００２６】ここで、［Ｐ］＋０．７・［Ｓｉ］が０．
１０未満では、酸性酸化物である燐酸（Ｐ２Ｏ５）や珪
酸（ＳｉＯ２）の生成量が少なくなるため石灰自体の滓
化が悪化する。すなわち、Ｐ２Ｏ５やＳｉＯ２とＣａＯ
との反応生成化合物をそれぞれ３ＣａＯ・Ｐ２Ｏ５や２
ＣａＯ・ＳｉＯ２とすると、［Ｐ］＋０．７・［Ｓｉ］
が０．１０未満の場合にはこれらの酸性酸化物で滓化で
きるＣａＯ量は高々３ｋｇ／溶銑ｔｏｎ程度であり、こ
れ以上のＣａＯ量を滓化させるためには酸化鉄などを極
端に増加させるなどの他の面倒な対策が必要となる。Here, [P] + 0.7 · [Si] is 0.1.
If it is less than 10, the amount of generated phosphoric acid (P 2 O 5 ) or silicic acid (SiO 2 ), which is an acidic oxide, is reduced, so that the lime itself is deteriorated. That is, P 2 O 5 or SiO 2 and CaO
Compounds produced by the reaction with 3CaO.P 2 O 5 and 2
If CaO · SiO 2 , [P] + 0.7 · [Si]
Is less than 0.10, the amount of CaO that can be slagged with these acidic oxides is at most about 3 kg / hot metal ton, and in order to slag a CaO amount higher than this, iron oxide and the like must be extremely increased. Other troublesome measures are required.

【００２７】また、［Ｐ］＋０．７・［Ｓｉ］が０．５
０を超えると、上記の酸性酸化物の生成量が多くなり過
ぎるため、石灰の滓化は向上するものの、生成するスラ
グの塩基度が低下したり、或いは塩基度を高めようとす
ると石灰が多量に必要となるため好ましくない。すなわ
ち、上記のようにＰ２Ｏ５やＳｉＯ２とＣａＯとの反応
生成化合物をそれぞれ３ＣａＯ・Ｐ２Ｏ５や２ＣａＯ・
ＳｉＯ２とすると、［Ｐ］＋０．７・［Ｓｉ］が０．５
０超の場合にはこれらの酸性酸化物で滓化できるＣａＯ
量は１５ｋｇ／溶銑ｔｏｎ以上にもなり、したがって、
これ以下のＣａＯ量では上記酸性酸化物を十分に固定で
きず、この結果、酸性酸化物がフリーに存在したり、或
いは還元されて浴中に再溶解することになる。[P] + 0.7 · [Si] is 0.5
If it exceeds 0, the amount of the above-mentioned acidic oxide generated becomes too large, so that the slag formation of lime is improved, but the basicity of the generated slag is reduced or the amount of lime is increased when trying to increase the basicity. It is not preferable because it is necessary for That is, as described above, the reaction product of P 2 O 5 or SiO 2 with CaO is 3CaO · P 2 O 5 or 2CaO ·
Assuming SiO 2 , [P] + 0.7 · [Si] is 0.5
If it exceeds 0, CaO which can be slagged with these acidic oxides
The amount can be more than 15kg / hot metal ton and therefore
If the amount of CaO is less than this, the above-mentioned acidic oxide cannot be fixed sufficiently, and as a result, the acidic oxide is present free or is reduced and redissolved in the bath.

【００２８】また、［Ｐ］は実質的に高燐鉱石の使用量
により決まる値であり、［Ｐ］が０．１０ｗｔ％未満で
は高燐鉱石の使用量が少なく、本発明を実施するメリッ
トが小さい。なお、高燐鉱石の使用量の観点から［Ｐ］
の好ましい下限は０．１２ｗｔ％である。このような最
適条件で脱燐処理を行うことにより、従来法のように高
珪素低燐溶銑に対して脱燐処理を行う場合に較べて同等
又はそれ以上の脱燐能を有するスラグを生成することが
できる。[P] is a value substantially determined by the amount of high phosphorous ore used. If [P] is less than 0.10 wt%, the amount of high phosphorous ore used is small, and there is an advantage in practicing the present invention. small. In addition, from the viewpoint of the amount of high phosphate ore used, [P]
Is preferably 0.12% by weight. By performing the dephosphorization treatment under such optimum conditions, a slag having a dephosphorization ability equivalent to or higher than that obtained by performing the dephosphorization treatment on the high-silicon low-phosphorus hot metal as in the conventional method is generated. be able to.

【００２９】さらに、高燐溶銑の脱燐処理では、溶銑の
燐濃度及び珪素濃度に応じて媒溶剤である石灰の添加量
やスラグ生成量に最適な範囲が存在し、この最適操業条
件で処理を行うことが好ましい。すなわち、溶銑の脱燐
処理に用いられる石灰の溶銑トン当たりの添加量Ｗｃ
（ｋｇ）と、高炉から出銑された溶銑の燐濃度［Ｐ］
（ｗｔ％）と、脱燐処理前の溶銑の珪素濃度［Ｓｉ］
（ｗｔ％）は下式を満足することが好ましい。 ３０≦Ｗｃ／（［Ｐ］＋０．７・［Ｓｉ］）≦１５０Further, in the dephosphorization treatment of the high-phosphorus hot metal, there is an optimum range for the amount of lime as a medium solvent and the amount of slag generated in accordance with the phosphorus concentration and the silicon concentration of the hot metal. Is preferably performed. That is, the addition amount Wc of lime used for dephosphorizing hot metal per ton of hot metal
(Kg) and the phosphorus concentration [P] of the hot metal spiked from the blast furnace
(Wt%) and the silicon concentration [Si] of the hot metal before the dephosphorization treatment
(Wt%) preferably satisfies the following expression. 30 ≦ Wc / ([P] + 0.7 · [Si]) ≦ 150

【００３０】ここで、Ｗｃ／（［Ｐ］＋０．７・［Ｓ
ｉ］）が３０未満では、生成する酸性酸化物の量に対し
て石灰の添加量が少な過ぎるため、滓化したスラグの塩
基度が低位となり、十分な脱燐効率が得られにくい。ま
た、Ｗｃ／（［Ｐ］＋０．７・［Ｓｉ］）が１５０を超
えると、生成する酸性酸化物の量に対して石灰の添加量
が多過ぎるため、石灰が未滓化になる傾向があり、この
場合も十分な脱燐効率が得られにくい。Here, Wc / ([P] + 0.7 · [S
If i]) is less than 30, the added amount of lime is too small with respect to the amount of generated acidic oxide, so that the slag slag has a low basicity, and it is difficult to obtain sufficient dephosphorization efficiency. Further, when Wc / ([P] + 0.7 · [Si]) exceeds 150, the amount of lime added is too large relative to the amount of generated acidic oxide, so that lime tends to be unslagged. In this case, too, it is difficult to obtain sufficient dephosphorization efficiency.

【００３１】さらに、溶銑の脱燐処理工程で発生する溶
銑トン当たりのスラグ量Ｗｓ（ｋｇ）と、高炉から出銑
された溶銑の燐濃度［Ｐ］（ｗｔ％）と、脱燐処理前の
溶銑の珪素濃度［Ｓｉ］（ｗｔ％）は下式を満足するこ
とが好ましい。 ４０≦Ｗｓ／（［Ｐ］＋０．７・［Ｓｉ］）≦２５０ ここで、Ｗｓ／（［Ｐ］＋０．７・［Ｓｉ］）が４０未
満では、生成する酸性酸化物のスラグ中での割合が高く
なるため、滓化したスラグの塩基度が低位となり、十分
な脱燐効率が得られにくい。また、Ｗｓ／（［Ｐ］＋
０．７・［Ｓｉ］）が２５０を超えると、生成する酸性
酸化物のスラグ中での割合が極端に低くなるため、添加
した石灰が未滓化になる傾向があり、この場合も十分な
脱燐効率が得られにくい。Further, the slag amount Ws (kg) per ton of hot metal generated in the hot metal dephosphorization process, the phosphorus concentration [P] (wt%) of hot metal discharged from the blast furnace, and The silicon concentration [Si] (wt%) of the hot metal preferably satisfies the following expression. 40 ≦ Ws / ([P] + 0.7 · [Si]) ≦ 250 Here, if Ws / ([P] + 0.7 · [Si]) is less than 40, the generated acidic oxide in the slag Since the ratio is high, the basicity of the slag that has become slag is low, and it is difficult to obtain sufficient dephosphorization efficiency. Also, Ws / ([P] +
If 0.7. [Si]) exceeds 250, the ratio of the generated acidic oxide in the slag becomes extremely low, so that the added lime tends to be unslagged. It is difficult to obtain dephosphorization efficiency.

【００３２】脱燐処理における滓化悪化は、環境上の問
題が指摘されているフッ素を多量に含む媒溶剤（蛍石）
の使用の有無に拘らず多かれ少なかれ問題となるが、上
記のような最適条件の下で脱燐処理を行った場合には少
ないスラグ量で高い除去効率が得られるものであり、し
たがって、このような最適条件での脱燐処理は、フッ素
を多量に含む媒溶剤（蛍石）の使用量を削減し或いはフ
ッ素を含まない媒溶剤を使用する場合に特に有効であ
る。Deterioration in the dephosphorization treatment is considered to be an environmental problem. A medium solvent containing a large amount of fluorine (fluorite) has been pointed out.
This is more or less a problem regardless of the use of slag.However, when the dephosphorization treatment is performed under the above-mentioned optimum conditions, a high removal efficiency can be obtained with a small amount of slag. The dephosphorization treatment under optimal conditions is particularly effective when the amount of a medium solvent containing a large amount of fluorine (fluorite) is reduced or when a medium solvent containing no fluorine is used.

【００３３】脱燐処理に使用する容器に特別な制約はな
く、脱珪素処理と同様に溶銑搬送容器である溶銑鍋や装
入鍋などの取鍋、トピードカーなどを用いて行うことも
できるし、転炉型容器を用いて行うこともできる。また
場合によっては、同一容器内で前記脱珪処理と脱燐処理
を順次実施してもよい。この脱燐処理では、通常、脱燐
反応を効果的に高めるために溶銑中に酸素源として気体
酸素（酸素ガスまたは酸素含有ガス）及び／又は固体酸
素源（例えば、鉄鉱石やミルスケールなどの酸化鉄）を
媒溶剤とともに添加する。このうち気体酸素については
ランスによる上吹きや溶銑中へのインジェクション或い
は底吹きなどの任意の方法により、また、固体酸素源や
媒溶剤については上置き装入やインジェクションなどの
任意の方法により、それぞれに溶銑中に供給される。ま
た、脱燐を効率的に行うためのより基本的な条件とし
て、溶銑に対して適正な撹拌を行う必要がある。この撹
拌としては、一般に浸漬ランスなどを利用したガス撹拌
が行われる。There is no particular limitation on the container used for the dephosphorization treatment, and the dephosphorization treatment can be performed using a ladle such as a hot metal pot or a charging pan, a topped car, or the like, which is a hot metal transfer vessel, similarly to the silicon removal treatment. It can also be performed using a converter type container. In some cases, the desiliconization treatment and the dephosphorization treatment may be sequentially performed in the same container. In this dephosphorization treatment, gaseous oxygen (oxygen gas or oxygen-containing gas) and / or a solid oxygen source (for example, iron ore or mill scale) is usually used as an oxygen source in the hot metal in order to effectively enhance the dephosphorization reaction. (Iron oxide) is added together with a solvent. Of these, for gaseous oxygen, any method such as top blowing with a lance, injection into hot metal or bottom blowing, and for solid oxygen source or medium solvent by any method such as overhead charging or injection, respectively. Is supplied into the hot metal. In addition, as a more basic condition for efficiently performing the dephosphorization, it is necessary to perform appropriate stirring on the hot metal. As this stirring, gas stirring using an immersion lance or the like is generally performed.

【００３４】上記のようにして脱燐処理された後の低燐
溶銑は、転炉での脱炭処理に供される。本発明法におけ
る転炉脱炭工程では事前に溶銑の実質的な脱燐が完了し
ているため、従来法のように脱炭工程で実質的な脱燐を
行う必要が全く、このため媒溶剤で生成させるスラグ量
は少量でよい。すなわち、吹錬時の生成酸化鉄の薄め材
としてや、浴面からの粒滴の飛散や放熱を抑制するため
に多少のカバースラグは必要であり、またマンガン鉱石
を添加した際に混入する少量の脈石分に対して媒溶剤を
添加してスラグ調整する必要はあるが、その場合でも媒
溶剤で生成させるスラグ量は極く少量でよい。また、上
述したようにスラグの精錬能（脱燐能）が必須ではな
く、スラグ組成の多少の変動も問題ないため、炉内への
スラグ残し操業などによりスラグを繰り返し使用するこ
と、すなわち、実質的に媒溶剤を使用せず、前チャージ
またはそれ以前のチャージに生成したスラグを主として
使用した操業を行うことができ、処理溶湯１トンに対し
スラグの発生量を１０ｋｇ以下の最小限に抑えることが
できる。The low-phosphorus molten iron after the dephosphorization treatment as described above is subjected to a decarburization treatment in a converter. In the converter decarburization step of the present invention, since the substantial dephosphorization of the hot metal has been completed in advance, there is no need to perform substantial dephosphorization in the decarburization step as in the conventional method. The amount of slag generated by the method may be small. That is, some cover slag is necessary as a thinner for iron oxide generated during blowing and to suppress scattering and heat radiation of droplets from the bath surface, and a small amount of slag mixed when manganese ore is added Although it is necessary to adjust the slag by adding a solvent to the gangue, the amount of slag generated by the solvent may be very small. Further, as described above, the refining ability (dephosphorization ability) of the slag is not essential, and there is no problem with a slight variation in the slag composition. Therefore, the slag is repeatedly used by operating the slag in the furnace, that is, the slag is substantially used. It is possible to carry out operations mainly using slag generated in the previous charge or previous charge without using a medium solvent, and to minimize the amount of slag generated to 10 kg or less per ton of treated molten metal. Can be.

【００３５】また、本発明の他の実施形態においては、
脱炭処理工程で生じたスラグ（脱炭スラグ）の一部また
は全部を脱燐処理の媒溶剤として用いる。脱炭スラグは
少なくとも部分的には溶融状態で発生したものであるた
め低温の脱燐処理でも石灰に較べて滓化しやすく、しか
も、脱炭スラグ中には燐酸が少ない上、鉄やマンガンの
有効成分が主に酸化物の形態で含まれているので、これ
らを被還元元素として有効に回収でき、また、燐の酸化
剤としても作用するため脱燐処理の媒溶剤として好適で
ある。このため、脱炭処理した転炉で排滓したスラグを
そのまま又は冷却した後、脱燐処理工程でスラグとして
用いる。In another embodiment of the present invention,
Part or all of the slag (decarburized slag) generated in the decarburization process is used as a solvent for the dephosphorization process. Since the decarburized slag is generated at least partially in the molten state, it is easier to slag than lime even at low-temperature dephosphorization, and the decarburized slag contains less phosphoric acid and is effective for iron and manganese. Since the components are mainly contained in the form of oxides, they can be effectively recovered as elements to be reduced, and also act as an oxidizing agent for phosphorus, so that they are suitable as a solvent for dephosphorization. For this reason, the slag discharged from the decarburized converter is used as slag in the dephosphorization step after being cooled or cooled.

【００３６】従来行われている低燐溶銑の脱燐処理にお
いても、製鋼スラグを削減する方法として脱炭スラグを
脱燐処理の媒溶剤として用いる方法が知られている。し
かし、脱炭スラグ中のＣａＯは転炉脱炭工程で発生した
珪酸とも部分的に結合した状態であり、溶銑脱燐時に発
生する珪酸分も考慮して脱燐に有効な高塩基度の条件を
確保するには、多量の媒溶剤の添加が必要であった。こ
のため媒溶剤の添加量やスラグ量の削減効果はあまり期
待できなかった。これに対して本発明では溶銑を事前に
低珪素化しているため、脱燐処理工程で珪酸を含む脱炭
スラグを用いても容易にスラグ塩基度（ＣａＯ／ＳｉＯ
２）を高めることができ、脱燐能が高いスラグを生成さ
せることができる。また、このように脱炭スラグを脱燐
処理に有効利用できるため、脱燐処理の媒溶剤の添加量
やスラグ発生量を効果的に削減することができる。In the conventional dephosphorization of low-phosphorus hot metal, a method of using decarburized slag as a solvent for dephosphorization is known as a method of reducing steelmaking slag. However, CaO in the decarburized slag is partially bound to the silicic acid generated in the converter decarburization step, and the conditions of high basicity effective for dephosphorization taking into account the silicic acid generated during hot metal dephosphorization are taken into account. In order to ensure the above, it was necessary to add a large amount of a solvent. For this reason, the effect of reducing the amount of the solvent added or the amount of slag could not be expected so much. On the other hand, in the present invention, since the molten iron is reduced to silicon in advance, the slag basicity (CaO / SiO 2) is easily obtained even if decarburized slag containing silicic acid is used in the dephosphorization step.
2 ) can be increased, and slag having high dephosphorization ability can be produced. In addition, since the decarburized slag can be effectively used for the dephosphorization treatment as described above, the amount of the solvent added for the dephosphorization treatment and the amount of slag generated can be effectively reduced.

【００３７】この実施形態の場合、溶銑中の燐濃度及び
珪素濃度に応じた石灰（媒溶剤）の添加量やスラグ生成
量に関する最適操業条件は以下のようになる。すなわ
ち、溶銑の脱燐処理に用いられる石灰（媒溶剤として新
たに添加される石灰）の溶銑トン当たりの添加量Ｗｃ
（ｋｇ）と、高炉から出銑された溶銑の燐濃度［Ｐ］
（ｗｔ％）と、脱燐処理前の溶銑の珪素濃度［Ｓｉ］
（ｗｔ％）は下式を満足することが好ましい。 Ｗｃ／（［Ｐ］＋０．７・［Ｓｉ］）≦１５０ ここで、Ｗｃ／（［Ｐ］＋０．７・［Ｓｉ］）が１５０
を超えると、生成する酸性酸化物の量に対して石灰の添
加量が多過ぎるため、石灰が未滓化になる傾向があり十
分な脱燐効率が得られにくい。In the case of this embodiment, the optimum operating conditions relating to the amount of lime (medium solvent) added and the amount of slag generated in accordance with the phosphorus concentration and the silicon concentration in the hot metal are as follows. That is, the added amount Wc per ton of hot metal of lime (lime newly added as a solvent) used for the dephosphorization of hot metal.
(Kg) and the phosphorus concentration [P] of the hot metal spiked from the blast furnace
(Wt%) and the silicon concentration [Si] of the hot metal before the dephosphorization treatment
(Wt%) preferably satisfies the following expression. Wc / ([P] + 0.7 · [Si]) ≦ 150 where Wc / ([P] + 0.7 · [Si]) is 150
If it exceeds 3, the amount of lime to be added is too large with respect to the amount of generated acidic oxide, so that the lime tends to be slag-free and it is difficult to obtain sufficient dephosphorization efficiency.

【００３８】また、溶銑の脱燐処理工程で新たに発生す
る溶銑トン当たりのスラグ量Ｗｓ（ｋｇ）と、高炉から
出銑された溶銑の燐濃度［Ｐ］（ｗｔ％）と、脱燐処理
前の溶銑の珪素濃度［Ｓｉ］（ｗｔ％）は下式を満足す
ることが好ましい。 Ｗｓ／（［Ｐ］＋０．７・［Ｓｉ］）≦２５０ ここで、脱燐処理工程で新たに発生するスラグ量とは、
炉壁に付着するなどして炉内に残留していた前チャージ
のスラグが当該チャージの処理中に脱落や溶解などによ
ってスラグ化したものを除き、当該チャージにおいて、
添加した媒溶剤などの添加物、溶銑からの酸化生成物及
び炉体自体の溶損などにより生成するスラグの総量を指
す。 Ｗｓ／（［Ｐ］＋０．７・［Ｓｉ］）が２５０を超える
と、生成する酸性酸化物のスラグ中での割合が極端に低
くなるため、添加した石灰が未滓化になる傾向があり、
十分な脱燐効率が得られにくい。Further, the amount of slag Ws (kg) per ton of hot metal newly generated in the hot metal dephosphorization process, the phosphorus concentration [P] (wt%) of hot metal discharged from the blast furnace, the dephosphorization process It is preferable that the silicon concentration [Si] (wt%) of the previous hot metal satisfies the following expression. Ws / ([P] + 0.7 · [Si]) ≦ 250 Here, the amount of slag newly generated in the dephosphorization step is:
Except for the slag of the pre-charge remaining in the furnace, such as by adhering to the furnace wall, which has become slag due to dropping or melting during the processing of the charge,
It refers to the total amount of slag generated by additives such as added medium solvents, oxidation products from hot metal, and erosion of the furnace body itself. If Ws / ([P] + 0.7 · [Si]) exceeds 250, the ratio of the generated acidic oxide in the slag becomes extremely low, so that the added lime tends to be slag-free. ,
It is difficult to obtain sufficient dephosphorization efficiency.

【００３９】このように脱炭スラグを脱燐処理の媒溶剤
として使用する本発明の実施形態では、滓化しやすい脱
炭スラグを利用し且つ高塩基度のスラグを得やすいの
で、フッ素を多量に含む媒溶剤（蛍石）の使用量を削減
し或いはフッ素を含まない媒溶剤を使用することによっ
てスラグの脱燐能が低下した場合にも、効率的な脱燐を
行うことができるため好ましい。As described above, in the embodiment of the present invention in which the decarburized slag is used as a medium solvent for the dephosphorization treatment, the decarburized slag which is easily formed into a slag is used and a slag having a high basicity is easily obtained. Even if the dephosphorizing ability of the slag is reduced by reducing the amount of the solvent solvent (fluorite) contained or using a solvent solvent containing no fluorine, it is preferable because efficient dephosphorization can be performed.

【００４０】[0040]

【実施例】［実施例１］高炉から出銑された溶銑に対
し、鋳床脱硅−鍋脱硅（溶銑鍋での脱珪）−転炉脱燐−
転炉脱炭を行う一連の工程で溶銑の精錬を行った。この
実施例では、燐濃度が０．０９ｗｔ％の鉄鉱石を全鉄鉱
石使用量の０〜７０ｗｔ％の範囲で変化させ、高炉にお
いて溶銑を製造した。[Example 1] [Example 1] Cast iron de-siliconization-pot desiliconization (de-siliconization in hot metal pot) -converter dephosphorization-
Hot metal refining was performed in a series of steps for converter decarburization. In this example, iron ore having a phosphorus concentration of 0.09 wt% was changed in the range of 0 to 70 wt% of the total iron ore usage, and hot metal was produced in a blast furnace.

【００４１】高炉から出銑された溶銑を鋳床で脱珪する
際に、粉状のミルスケールと焼結鉱粉を上置き装入によ
り添加した。また、スラグ中の酸素を脱珪反応に効率的
に利用するため鋳床から溶銑鍋までの一連の脱珪処理工
程中は排滓は行わず、スラグと溶銑を反応させた。溶銑
鍋での脱珪処理では、浸漬ランスから窒素ガスを約０．
０１Ｎｍ３／ｍｉｎ・溶銑ｔｏｎで浴中に吹き込み、溶
銑を撹拌するとともにスラグ反応を進行させた。また、
必要な脱珪量に応じ気体酸素や酸化鉄を添加した。When the hot metal discharged from the blast furnace was desiliconized in the casting bed, a powdery mill scale and sintered ore powder were added by overhead charging. In addition, in order to efficiently utilize oxygen in the slag for the desiliconization reaction, slag and the hot metal were reacted during the series of desiliconization treatment steps from the casting bed to the hot metal ladle without the waste. In the desiliconization treatment in the hot metal pot, nitrogen gas is supplied from the dipping lance to about 0.
The hot metal was blown into the bath at a rate of 01 Nm 3 / min · hot metal ton, the hot metal was stirred, and the slag reaction was allowed to proceed. Also,
Gaseous oxygen and iron oxide were added according to the required amount of desiliconization.

【００４２】溶銑を溶銑鍋で所定の珪素濃度まで脱珪処
理した後、生成したスラグを排滓し、次いで溶銑脱燐を
行うための３００トン転炉に溶銑を装入した。脱燐処理
のために必要な石灰量は溶銑の珪素濃度及び燐濃度に応
じて決められるため、低珪素溶銑を脱燐処理する場合に
は石灰投入量は少なくなり、このため各実施例によって
生成した脱燐スラグ量にも差が生じた。また、終点のス
ラグの酸化度を低位とするため、スラグ中の全酸化鉄濃
度の指標である［Ｔ．Ｆｅ］濃度は５ｗｔ％以下とし
た。After the hot metal was desiliconized to a predetermined silicon concentration in a hot metal pot, the generated slag was discharged, and then the hot metal was charged into a 300 ton converter for hot metal dephosphorization. Since the amount of lime required for dephosphorization is determined according to the silicon concentration and the phosphorus concentration of the hot metal, the amount of lime input decreases when dephosphorizing low-silicon hot metal. There was also a difference in the amount of dephosphorized slag obtained. In addition, in order to lower the oxidation degree of the slag at the end point, it is an index of the total iron oxide concentration in the slag [T. Fe] concentration was 5 wt% or less.

【００４３】転炉での脱燐処理が終了した溶銑は、一旦
鍋に出湯した後、別の転炉に再装入し、最終脱炭を主目
的とした処理（脱炭処理）を行った。この処理では、炉
底部から約０．１Ｎｍ３／ｍｉｎ・溶銑ｔｏｎの窒素又
はアルゴンガスを吹き込んで浴の撹拌を行いつつ、浴上
部から送酸を行った。この脱炭処理では必要なマンガン
量に応じてマンガン鉱石も添加され、このマンガン鉱石
から混入する珪酸に対してスラグの塩基度が３．５に調
整されるように石灰源を添加した。脱炭処理後のスラグ
はその全量は排滓せず、炉内に１５〜４５ｋｇ／溶銑ｔ
ｏｎ相当残留する状態で処理を連続して行った。また、
この脱炭処理では処理終了時の溶鋼中炭素濃度がほぼ
０．０７ｗｔ％、溶鋼温度がほぼ１６４５℃になるよう
に制御した。The hot metal after the dephosphorization treatment in the converter is once discharged into a pot and then recharged into another converter to perform a treatment mainly for final decarburization (decarburization treatment). . In this treatment, acid was fed from the upper part of the bath while stirring the bath by blowing nitrogen or argon gas of about 0.1 Nm 3 / min · hot metal ton from the furnace bottom. In this decarburization treatment, manganese ore was also added in accordance with the required amount of manganese, and a lime source was added so that the basicity of slag was adjusted to 3.5 with respect to silicic acid mixed in from the manganese ore. The slag after the decarburization treatment does not discharge the whole amount, and 15-45 kg / hot metal t
The treatment was continuously performed in a state where the amount corresponding to “on” remained. Also,
In this decarburization treatment, the carbon concentration in the molten steel at the end of the treatment was controlled to be approximately 0.07 wt%, and the molten steel temperature was controlled to be approximately 1645 ° C.

【００４４】各実施例について、一連の製造・処理条件
とその結果を表１及び表２に示す。同表によれば、脱燐
処理前の溶銑の珪素濃度を０．２０ｗｔ％以下とした本
発明例では、鉄鉱石の一部に高燐鉱石を使用しているに
も拘らず、少ない石灰添加量と生成スラグ量で脱燐処理
を行うことにより低燐溶鋼を製造できることが判る。こ
れに対して、鉄鉱石の一部に高燐鉱石を使用し、且つ脱
燐処理前の溶銑の珪素濃度が０．２０ｗｔ％を超える比
較例では、高燐鉱石の使用割合が同等の本発明例に較べ
て石灰添加量と生成スラグ量が大幅に増加している。Tables 1 and 2 show a series of manufacturing and processing conditions and the results for each example. According to the table, in the example of the present invention in which the silicon concentration of the hot metal before the dephosphorization treatment was 0.20 wt% or less, a small amount of lime was added in spite of using high phosphate ore for a part of the iron ore. It can be seen that low phosphorus molten steel can be produced by performing the dephosphorization treatment with the amount and the generated slag. On the other hand, in a comparative example in which high phosphorus ore is used as a part of iron ore and the silicon concentration of the hot metal before the dephosphorization treatment exceeds 0.20 wt%, the present invention in which the usage ratio of high phosphorus ore is the same Compared with the example, the amount of lime added and the amount of generated slag are greatly increased.

【００４５】[0045]

【表１】 [Table 1]

【００４６】[0046]

【表２】 [Table 2]

【００４７】［実施例２］高炉から出銑された溶銑に対
し、鋳床脱硅−鍋脱硅（溶銑鍋での脱珪）−取鍋脱燐−
転炉脱炭を行う一連の工程で溶銑の精錬を行った。この
実施例では、燐濃度が０．０９ｗｔ％の鉄鉱石を全鉄鉱
石使用量の０〜７０ｗｔ％の範囲で変化させ、高炉にお
いて溶銑を製造した。[Example 2] Cast iron removal from a blast furnace, de-siliconization in a hot pot, de-siliconization in a ladle (de-siliconization in a ladle)-dephosphorization in a ladle-
Hot metal refining was performed in a series of steps for converter decarburization. In this example, iron ore having a phosphorus concentration of 0.09 wt% was changed in the range of 0 to 70 wt% of the total iron ore usage, and hot metal was produced in a blast furnace.

【００４８】高炉から出銑された溶銑を鋳床で脱珪する
際に、粉状のミルスケールと焼結鉱粉を上置き装入によ
り添加した。また、スラグ中の酸素を脱珪反応に効率的
に利用するため鋳床から溶銑鍋までの一連の脱珪処理工
程中は排滓は行わず、スラグと溶銑を反応させた。溶銑
鍋での脱珪処理では、浸漬ランスから窒素ガスを約０．
０１Ｎｍ３／ｍｉｎ・溶銑ｔｏｎで浴中に吹き込み、溶
銑を撹拌するとともにスラグ反応を進行させた。また、
必要な脱珪量に応じ気体酸素や酸化鉄を添加した。When de-siliconizing hot metal discharged from a blast furnace in a cast bed, powdery mill scale and sintered ore powder were added by overhead charging. In addition, in order to efficiently utilize oxygen in the slag for the desiliconization reaction, slag and the hot metal were reacted during the series of desiliconization treatment steps from the casting bed to the hot metal ladle without the waste. In the desiliconization treatment in the hot metal pot, nitrogen gas is supplied from the dipping lance to about 0.
The hot metal was blown into the bath at a rate of 01 Nm 3 / min · hot metal ton, the hot metal was stirred, and the slag reaction was allowed to proceed. Also,
Gaseous oxygen and iron oxide were added according to the required amount of desiliconization.

【００４９】溶銑を溶銑鍋で所定の珪素濃度まで脱珪処
理した後、生成したスラグを排滓し、次いで溶銑脱燐を
行った。この取鍋での脱燐処理では、石灰は全量インジ
ェクションとし、１本の浸漬ランスから毎分１Ｎｍ３の
流量のキャリアガス（窒素ガス）とともに浴中に吹き込
んだ。脱燐処理のために必要な石灰量は溶銑の珪素濃度
及び燐濃度に応じて決められるため、低珪素溶銑を脱燐
処理する場合には石灰投入量は少なくなり、このため各
実施例によって生成した脱燐スラグ量にも差が生じた。
また、終点のスラグの酸化度を低位とするため、スラグ
中の全酸化鉄濃度の指標である［Ｔ．Ｆｅ］濃度は５ｗ
ｔ％以下とした。After the hot metal was desiliconized to a predetermined silicon concentration in a hot metal pot, the generated slag was discharged, and then hot metal dephosphorization was performed. In this dephosphorization treatment with a ladle, the lime was injected as a whole, and was blown into the bath together with a carrier gas (nitrogen gas) at a flow rate of 1 Nm 3 per minute from one dipping lance. Since the amount of lime required for dephosphorization is determined according to the silicon concentration and the phosphorus concentration of the hot metal, the amount of lime input decreases when dephosphorizing low-silicon hot metal. There was also a difference in the amount of dephosphorized slag obtained.
In addition, in order to lower the oxidation degree of the slag at the end point, it is an index of the total iron oxide concentration in the slag [T. Fe] concentration is 5w
t% or less.

【００５０】取鍋での脱燐処理が終了した溶銑を転炉に
装入し、最終脱炭を主目的とした処理（脱炭処理）を行
った。この処理では、炉底部から約０．１Ｎｍ３／ｍｉ
ｎ・溶銑ｔｏｎの窒素又はアルゴンガスを吹き込んで浴
の撹拌を行いつつ、浴上部から送酸を行った。この脱炭
処理では必要なマンガン量に応じてマンガン鉱石も添加
され、このマンガン鉱石から混入する珪酸に対してスラ
グの塩基度が３．５に調整されるように石灰源を添加し
た。脱炭処理後のスラグはその全量は排滓せず、炉内に
１５〜４５ｋｇ／溶銑ｔｏｎ相当残留する状態で処理を
連続して行った。また、この脱炭処理では処理終了時の
溶鋼中炭素濃度がほぼ０．０７ｗｔ％、溶鋼温度がほぼ
１６４５℃になるように制御した。The hot metal that had been dephosphorized in the ladle was charged into a converter and subjected to a treatment mainly for final decarburization (decarburization treatment). In this treatment, about 0.1 Nm 3 / mi from the furnace bottom
Nitrogen or argon gas of n-hot metal ton was blown in to stir the bath, and the acid was fed from the upper part of the bath. In this decarburization treatment, manganese ore was also added in accordance with the required amount of manganese, and a lime source was added so that the basicity of slag was adjusted to 3.5 with respect to silicic acid mixed in from the manganese ore. The slag after the decarburization treatment was continuously treated in such a state that the entire amount thereof was not discharged and remained in the furnace at a rate of 15 to 45 kg / hot metal ton. In this decarburization treatment, the carbon concentration in the molten steel at the end of the treatment was controlled to be approximately 0.07 wt%, and the molten steel temperature was controlled to be approximately 1645 ° C.

【００５１】各実施例について、一連の製造・処理条件
とその結果を表３に示す。同表によれば、脱燐処理前の
溶銑の珪素濃度を０．２０ｗｔ％以下とした本発明例で
は、鉄鉱石の一部に高燐鉱石を使用しているにも拘ら
ず、少ない石灰添加量と生成スラグ量で脱燐処理を行う
ことにより低燐溶鋼を製造できることが判る。これに対
して、鉄鉱石の一部に高燐鉱石を使用し、且つ脱燐処理
前の溶銑の珪素濃度が０．２０ｗｔ％を超える比較例で
は、高燐鉱石の使用割合が同等の本発明例に較べて、石
灰添加量と生成スラグ量が大幅に増加している。Table 3 shows a series of manufacturing and processing conditions and results for each example. According to the table, in the example of the present invention in which the silicon concentration of the hot metal before the dephosphorization treatment was 0.20 wt% or less, a small amount of lime was added in spite of using high phosphate ore for a part of the iron ore. It can be seen that low phosphorus molten steel can be produced by performing the dephosphorization treatment with the amount and the generated slag. On the other hand, in a comparative example in which high phosphorus ore is used as a part of iron ore and the silicon concentration of the hot metal before the dephosphorization treatment exceeds 0.20 wt%, the present invention in which the usage ratio of high phosphorus ore is the same Compared with the example, the amount of lime added and the amount of slag produced are greatly increased.

【００５２】[0052]

【表３】 [Table 3]

【００５３】［実施例３］高炉から出銑された溶銑に対
し、鋳床脱硅−鍋脱硅（溶銑鍋での脱珪）−転炉脱燐−
転炉脱炭を行う一連の工程で溶銑の精錬を行った。この
実施例では、燐濃度が０．１２ｗｔ％の鉄鉱石を全鉄鉱
石使用量の０〜５０ｗｔ％の範囲で変化させ、高炉にお
いて溶銑を製造した。[Example 3] Cast iron de-siliconization-pot de-siliconization (de-siliconization in hot metal pot) -converter dephosphorization-
Hot metal refining was performed in a series of steps for converter decarburization. In this example, iron ore having a phosphorus concentration of 0.12 wt% was changed in the range of 0 to 50 wt% of the total iron ore usage, and hot metal was produced in a blast furnace.

【００５４】高炉から出銑された溶銑を鋳床で脱珪する
際に、粉状のミルスケールと焼結鉱粉を上置き装入によ
り添加した。また、スラグ中の酸素を脱珪反応に効率的
に利用するため鋳床から溶銑鍋までの一連の脱珪処理工
程中は排滓は行わず、スラグと溶銑を反応させた。溶銑
鍋での脱珪処理では、浸漬ランスから窒素ガスを約０．
０１Ｎｍ３／ｍｉｎ・溶銑ｔｏｎで浴中に吹き込み、溶
銑を撹拌するとともにスラグ反応を進行させた。また、
必要な脱珪量に応じ気体酸素や酸化鉄を添加した。When the hot metal discharged from the blast furnace was desiliconized in the casting bed, powdery mill scale and sintered ore powder were added by overhead charging. In addition, in order to efficiently utilize oxygen in the slag for the desiliconization reaction, slag and the hot metal were reacted during the series of desiliconization treatment steps from the casting bed to the hot metal ladle without the waste. In the desiliconization treatment in the hot metal pot, nitrogen gas is supplied from the dipping lance to about 0.
The hot metal was blown into the bath at a rate of 01 Nm 3 / min · hot metal ton, the hot metal was stirred, and the slag reaction was allowed to proceed. Also,
Gaseous oxygen and iron oxide were added according to the required amount of desiliconization.

【００５５】溶銑を溶銑鍋で所定の珪素濃度まで脱珪処
理した後、生成したスラグを排滓し、次いで溶銑脱燐を
行うための３００トン転炉に溶銑を装入した。この脱燐
処理工程では、次工程である脱炭処理工程で発生した脱
炭スラグを溶銑トン当り１５ｋｇ（一定量）用い、さら
に、装入された溶銑の珪素濃度と燐濃度に応じて必要な
量の石灰を用いた。低珪素溶銑を脱燐処理する場合には
石灰投入量は少なくなり、このため各実施例によって生
成した脱燐スラグ量にも差が生じた。また、終点のスラ
グの酸化度を低位とするため、スラグ中の全酸化鉄濃度
の指標である［Ｔ．Ｆｅ］濃度は５ｗｔ％以下とした。After the hot metal was desiliconized to a predetermined silicon concentration in a hot metal pot, the generated slag was discharged, and then the hot metal was charged into a 300 ton converter for hot metal dephosphorization. In this dephosphorization treatment step, 15 kg (constant amount) of decarburized slag generated in the next step of decarburization treatment is used per ton of hot metal, and furthermore, a necessary amount depends on the silicon concentration and the phosphorus concentration of the charged hot metal. A quantity of lime was used. When dephosphorizing low-silicon hot metal, the amount of lime input was reduced, and therefore, the amount of dephosphorized slag produced in each example was different. In addition, in order to lower the oxidation degree of the slag at the end point, it is an index of the total iron oxide concentration in the slag [T. Fe] concentration was 5 wt% or less.

【００５６】転炉での脱燐処理が終了した溶銑は、一旦
鍋に出湯した後、別の転炉に再装入し、最終脱炭を主目
的とした処理（脱炭処理）を行った。この処理では、炉
底部から約０．１Ｎｍ３／ｍｉｎ・溶銑ｔｏｎの窒素又
はアルゴンガスを吹き込んで浴の撹拌を行いつつ、浴上
部から送酸を行った。この脱炭処理では必要なマンガン
量に応じてマンガン鉱石も添加され、このマンガン鉱石
から混入する珪酸に対してスラグの塩基度が３．５に調
整されるように石灰源を添加した。また、この脱炭処理
では処理終了時の溶鋼中炭素濃度がほぼ０．０８ｗｔ
％、溶鋼温度がほぼ１６５０℃になるように制御した。The hot metal after the dephosphorization treatment in the converter is once discharged into a pot and then recharged into another converter to perform a treatment mainly for final decarburization (decarburization treatment). . In this treatment, acid was fed from the upper part of the bath while stirring the bath by blowing nitrogen or argon gas of about 0.1 Nm 3 / min · hot metal ton from the furnace bottom. In this decarburization treatment, manganese ore was also added in accordance with the required amount of manganese, and a lime source was added so that the basicity of slag was adjusted to 3.5 with respect to silicic acid mixed in from the manganese ore. In this decarburization treatment, the carbon concentration in the molten steel at the end of the treatment is almost 0.08 wt.
%, And the molten steel temperature was controlled to be approximately 1650 ° C.

【００５７】各実施例について、一連の製造・処理条件
とその結果を表４及び表５に示す。同表によれば、脱燐
処理前の溶銑の珪素濃度を０．２０ｗｔ％以下とした本
発明例では、鉄鉱石の一部に高燐鉱石を使用しているに
も拘らず、少ない石灰添加量と生成スラグ量で脱燐処理
を行うことにより低燐溶鋼を製造できることが判る。こ
れに対して、鉄鉱石の一部に高燐鉱石を使用し、且つ脱
燐処理前の溶銑の珪素濃度が０．２０ｗｔ％を超える比
較例では、高燐鉱石の使用割合が同等の本発明例に較べ
て、石灰添加量と生成スラグ量が大幅に増加している。Tables 4 and 5 show a series of manufacturing and processing conditions and results for each example. According to the table, in the example of the present invention in which the silicon concentration of the hot metal before the dephosphorization treatment was 0.20 wt% or less, a small amount of lime was added in spite of using high phosphate ore for a part of the iron ore. It can be seen that low phosphorus molten steel can be produced by performing the dephosphorization treatment with the amount and the generated slag. On the other hand, in a comparative example in which high phosphorus ore is used as a part of iron ore and the silicon concentration of the hot metal before the dephosphorization treatment exceeds 0.20 wt%, the present invention in which the usage ratio of high phosphorus ore is the same Compared with the example, the amount of lime added and the amount of slag produced are greatly increased.

【００５８】[0058]

【表４】 [Table 4]

【００５９】[0059]

【表５】 [Table 5]

【００６０】[0060]

【発明の効果】以上述べたように本発明によれば、高炉
用鉄源として高燐濃度の鉄鉱石を大量に利用することが
でき、この高燐濃度の鉄鉱石を原料として得られた溶銑
を高い脱燐効率で脱燐処理し、しかも媒溶剤の添加量や
スラグなどの発生物の量も極力低減することができる。
また、本願の請求項５ないし請求項７に係る発明によれ
ば、脱炭処理工程で生じたスラグの一部又は全部を脱燐
処理工程で用いることにより、脱燐効率の向上とスラグ
発生量の削減をより効果的に図ることがでる。As described above, according to the present invention, a large amount of iron ore having a high phosphorus concentration can be used as an iron source for a blast furnace, and the hot metal obtained by using the iron ore having a high phosphorus concentration as a raw material can be used. Can be dephosphorized with high dephosphorization efficiency, and the amount of a solvent added and the amount of generated products such as slag can be reduced as much as possible.
Further, according to the invention according to claims 5 to 7 of the present application, by using a part or all of the slag generated in the decarburization treatment step in the dephosphorization treatment step, the improvement of the dephosphorization efficiency and the slag generation amount are achieved. Can be more effectively reduced.

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

【図１】溶銑鍋を用いた脱珪処理状況の一例を模式的に
示す説明図FIG. 1 is an explanatory view schematically showing an example of a desiliconization process using a hot metal pot.

【符号の説明】[Explanation of symbols]

１…溶銑鍋、２…送酸ランス、３…浸漬ランス、４…原
料投入装置1. Hot metal ladle, 2. Acid lance, 3. Dipping lance, 4. Raw material feeding device

───────────────────────────────────────────────────── フロントページの続き (72)発明者 清水 宏 東京都千代田区丸の内一丁目１番２号 日 本鋼管株式会社内 (72)発明者 渡辺 敦 東京都千代田区丸の内一丁目１番２号 日 本鋼管株式会社内 (72)発明者 田中 秀栄 東京都千代田区丸の内一丁目１番２号 日 本鋼管株式会社内 (72)発明者 野田 英俊 東京都千代田区丸の内一丁目１番２号 日 本鋼管株式会社内 (72)発明者 市川 孝一 東京都千代田区丸の内一丁目１番２号 日 本鋼管株式会社内 Ｆターム(参考） 4K013 BA03 CB03 4K014 AA01 AA03 AD23  ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Shimizu 1-1-2 Marunouchi, Chiyoda-ku, Tokyo, Japan Inside Nihon Kokan Co., Ltd. (72) Atsushi Watanabe 1-1-2, Marunouchi, Chiyoda-ku, Tokyo, Japan Inside the Honko Co., Ltd. (72) Inventor Hideei Tanaka 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Japan Inside the Honko Co., Ltd. (72) Inventor Hidetoshi Noda 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Japan Co., Ltd. (72) Inventor Koichi Ichikawa 1-2-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. F-term (reference) 4K013 BA03 CB03 4K014 AA01 AA03 AD23

Claims (7)

【特許請求の範囲】[Claims] 【請求項１】 高炉内に鉄源の一部又は全部として燐濃
度が０．０６ｗｔ％以上の鉄鉱石を装入する工程と、高
炉からの出銑ままで又は高炉出銑後の脱珪処理を経るこ
とで珪素濃度が０．２０ｗｔ％以下の溶銑を得る工程
と、該工程を経た低珪素溶銑を脱燐処理する工程と、該
脱燐処理工程を経た溶銑を脱炭処理する工程とを、少な
くとも有することを特徴とする高燐鉱石を原料とする鉄
鋼製造方法。1. A step of charging iron ore having a phosphorus concentration of 0.06% by weight or more as a part or all of an iron source in a blast furnace, and a desiliconization treatment with or without tapping from the blast furnace. A step of obtaining hot metal having a silicon concentration of 0.20 wt% or less by passing through, a step of dephosphorizing the low silicon hot metal that has passed through the step, and a step of decarburizing the hot metal that has passed through the dephosphorization step. , A steel production method using high phosphate rock as a raw material. 【請求項２】 高炉から出銑された溶銑の燐濃度［Ｐ］
（ｗｔ％）と脱燐処理前の溶銑の珪素濃度［Ｓｉ］（ｗ
ｔ％）が下式を満足することを特徴とする請求項１に記
載の高燐鉱石を原料とする鉄鋼製造方法。 ０．１０≦［Ｐ］＋０．７・［Ｓｉ］≦０．５０ ［Ｐ］≧０．１０2. Phosphorus concentration [P] of hot metal tapped from a blast furnace
(Wt%) and the silicon concentration [Si] (w
2. The method for producing steel from high phosphorous ore according to claim 1, wherein (t%) satisfies the following expression. 0.10 ≦ [P] + 0.7 · [Si] ≦ 0.50 [P] ≧ 0.10 【請求項３】 溶銑の脱燐処理に用いられる石灰の溶銑
トン当たりの添加量Ｗｃ（ｋｇ）と、高炉から出銑され
た溶銑の燐濃度［Ｐ］（ｗｔ％）と、脱燐処理前の溶銑
の珪素濃度［Ｓｉ］（ｗｔ％）が下式を満足することを
特徴とする請求項１又は２に記載の高燐鉱石を原料とす
る鉄鋼製造方法。 ３０≦Ｗｃ／（［Ｐ］＋０．７・［Ｓｉ］）≦１５０ ［Ｐ］≧０．１０3. An addition amount Wc (kg) of lime used for hot metal dephosphorization treatment per ton of hot metal, a phosphorus concentration [P] (wt%) of hot metal discharged from a blast furnace, and a value before dephosphorization treatment. 3. The method for producing steel from high phosphorous ore according to claim 1, wherein the silicon concentration [Si] (wt%) of the hot metal satisfies the following expression. 30 ≦ Wc / ([P] + 0.7 · [Si]) ≦ 150 [P] ≧ 0.10 【請求項４】 溶銑の脱燐処理工程で発生する溶銑トン
当たりのスラグ量Ｗｓ（ｋｇ）と、高炉から出銑された
溶銑の燐濃度［Ｐ］（ｗｔ％）と、脱燐処理前の溶銑の
珪素濃度［Ｓｉ］（ｗｔ％）が下式を満足することを特
徴とする請求項１、２又は３に記載の高燐鉱石を原料と
する鉄鋼製造方法。 ４０≦Ｗｓ／（［Ｐ］＋０．７・［Ｓｉ］）≦２５０ ［Ｐ］≧０．１０4. A slag amount Ws (kg) per ton of hot metal generated in a hot metal dephosphorization process, a phosphorus concentration [P] (wt%) of hot metal discharged from a blast furnace, and 4. The method for producing steel from high phosphorous ore according to claim 1, wherein the silicon concentration [Si] (wt%) of the hot metal satisfies the following expression. 40 ≦ Ws / ([P] + 0.7 · [Si]) ≦ 250 [P] ≧ 0.10. 【請求項５】 脱炭処理工程で生じたスラグの一部又は
全部を脱燐処理の媒溶剤として用いることを特徴とする
請求項１又は２に記載の高燐鉱石を原料とする鉄鋼製造
方法。5. The method according to claim 1, wherein a part or all of the slag generated in the decarburization treatment step is used as a solvent for the dephosphorization treatment. . 【請求項６】 溶銑の脱燐処理に用いられる石灰の溶銑
トン当たりの添加量Ｗｃ（ｋｇ）と、高炉から出銑され
た溶銑の燐濃度［Ｐ］（ｗｔ％）と、脱燐処理前の溶銑
の珪素濃度［Ｓｉ］（ｗｔ％）が下式を満足することを
特徴とする請求項５に記載の高燐鉱石を原料とする鉄鋼
製造方法。 Ｗｃ／（［Ｐ］＋０．７・［Ｓｉ］）≦１５０ ［Ｐ］≧０．１０6. An addition amount Wc (kg) of lime used for hot metal dephosphorization treatment per ton of hot metal, a phosphorus concentration [P] (wt%) of hot metal discharged from a blast furnace, and a value before dephosphorization treatment. The method for producing steel from high-phosphorus ore according to claim 5, wherein the silicon concentration [Si] (wt%) of the hot metal satisfies the following expression. Wc / ([P] + 0.7 · [Si]) ≦ 150 [P] ≧ 0.10 【請求項７】 溶銑の脱燐処理工程で新たに発生する溶
銑トン当たりのスラグ量Ｗｓ（ｋｇ）と、高炉から出銑
された溶銑の燐濃度［Ｐ］（ｗｔ％）と、脱燐処理前の
溶銑の珪素濃度［Ｓｉ］（ｗｔ％）が下式を満足するこ
とを特徴とする請求項５または６に記載の高燐鉱石を原
料とする鉄鋼製造方法。 Ｗｓ／（［Ｐ］＋０．７・［Ｓｉ］）≦２５０ ［Ｐ］≧０．１０7. A slag amount Ws (kg) per ton of hot metal newly generated in a hot metal dephosphorization process, a phosphorus concentration [P] (wt%) of hot metal discharged from a blast furnace, and a dephosphorization process. The method for producing steel using high phosphate rock as a raw material according to claim 5 or 6, wherein the silicon concentration [Si] (wt%) of the previous hot metal satisfies the following expression. Ws / ([P] + 0.7 · [Si]) ≦ 250 [P] ≧ 0.10
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JP2007131727A (en) * 2005-11-10 2007-05-31 Jfe Steel Kk Method for producing ferrocoke for metallurgical use
JP2007246786A (en) * 2006-03-17 2007-09-27 Jfe Steel Kk Ferrocoke and method for producing sintered ore
JP2009228101A (en) * 2008-03-25 2009-10-08 Nippon Steel Corp Method for pre-treating molten iron
KR101630986B1 (en) * 2014-12-19 2016-06-16 주식회사 포스코 Method of manufacturing low phosphor reduced iron using high phosphor iron ore
CN105950825A (en) * 2016-05-24 2016-09-21 攀钢集团攀枝花钢钒有限公司 Refining method of low-carbon and low-silicon manganese-contained aluminum killed steel liquid
CN110724784A (en) * 2019-10-14 2020-01-24 盐城市联鑫钢铁有限公司 Low-silicon high-phosphorus molten iron converter smelting method

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007131727A (en) * 2005-11-10 2007-05-31 Jfe Steel Kk Method for producing ferrocoke for metallurgical use
JP2007246786A (en) * 2006-03-17 2007-09-27 Jfe Steel Kk Ferrocoke and method for producing sintered ore
JP2009228101A (en) * 2008-03-25 2009-10-08 Nippon Steel Corp Method for pre-treating molten iron
KR101630986B1 (en) * 2014-12-19 2016-06-16 주식회사 포스코 Method of manufacturing low phosphor reduced iron using high phosphor iron ore
CN105950825A (en) * 2016-05-24 2016-09-21 攀钢集团攀枝花钢钒有限公司 Refining method of low-carbon and low-silicon manganese-contained aluminum killed steel liquid
CN105950825B (en) * 2016-05-24 2018-06-15 攀钢集团攀枝花钢钒有限公司 Low-carbon, low silicon, aluminum killed steel molten steel containing manganese method of refining
CN110724784A (en) * 2019-10-14 2020-01-24 盐城市联鑫钢铁有限公司 Low-silicon high-phosphorus molten iron converter smelting method

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