JP4984946B2 - Hot metal pretreatment method - Google Patents
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- JP4984946B2 JP4984946B2 JP2007033974A JP2007033974A JP4984946B2 JP 4984946 B2 JP4984946 B2 JP 4984946B2 JP 2007033974 A JP2007033974 A JP 2007033974A JP 2007033974 A JP2007033974 A JP 2007033974A JP 4984946 B2 JP4984946 B2 JP 4984946B2
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- 239000002184 metal Substances 0.000 title claims description 102
- 229910052751 metal Inorganic materials 0.000 title claims description 102
- 238000002203 pretreatment Methods 0.000 title claims description 8
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 32
- 229910052760 oxygen Inorganic materials 0.000 claims description 32
- 239000001301 oxygen Substances 0.000 claims description 32
- 239000007800 oxidant agent Substances 0.000 claims description 25
- 238000012545 processing Methods 0.000 claims description 19
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 17
- 238000007664 blowing Methods 0.000 claims description 17
- 239000007787 solid Substances 0.000 claims description 17
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 14
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 14
- 239000004571 lime Substances 0.000 claims description 14
- 239000003795 chemical substances by application Substances 0.000 claims description 13
- 238000002347 injection Methods 0.000 claims description 13
- 239000007924 injection Substances 0.000 claims description 13
- 229910052742 iron Inorganic materials 0.000 claims description 8
- 238000004898 kneading Methods 0.000 claims description 4
- 239000000428 dust Substances 0.000 claims description 3
- 238000000465 moulding Methods 0.000 claims 1
- 239000002893 slag Substances 0.000 description 16
- 238000000034 method Methods 0.000 description 12
- 238000006243 chemical reaction Methods 0.000 description 11
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 10
- 238000007796 conventional method Methods 0.000 description 7
- 230000007423 decrease Effects 0.000 description 6
- 239000000292 calcium oxide Substances 0.000 description 5
- 235000012255 calcium oxide Nutrition 0.000 description 5
- 238000002485 combustion reaction Methods 0.000 description 5
- 230000001590 oxidative effect Effects 0.000 description 5
- 238000007670 refining Methods 0.000 description 5
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 4
- 238000002474 experimental method Methods 0.000 description 4
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 3
- 229910052698 phosphorus Inorganic materials 0.000 description 3
- 239000011574 phosphorus Substances 0.000 description 3
- 238000009628 steelmaking Methods 0.000 description 3
- 229910004298 SiO 2 Inorganic materials 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- 239000000571 coke Substances 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000029142 excretion Effects 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000003672 processing method Methods 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 229910052717 sulfur Inorganic materials 0.000 description 2
- 239000011593 sulfur Substances 0.000 description 2
- 229910004261 CaF 2 Inorganic materials 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 235000019738 Limestone Nutrition 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 238000005261 decarburization Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000010436 fluorite Substances 0.000 description 1
- 239000006028 limestone Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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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
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- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
Description
本発明は、溶銑の予備処理方法に係わり、特に、処理容器に保持した溶銑中に、インジェクションランスを浸漬し、該インジェクションランスを介して酸化剤や造滓剤を吹き込み、該溶銑から脱珪、脱燐を行う技術に関する。 The present invention relates to a hot metal pretreatment method, and in particular, immersing an injection lance in hot metal held in a processing vessel, and blowing an oxidizing agent or a slagging agent through the injection lance, desiliconizing from the hot metal, The present invention relates to a technique for dephosphorization.
近年、製鋼工程では、転炉精錬の負荷軽減、精錬に要するトータル・コストの最小化を図るため、高炉から出銑した溶銑が含有する珪素（記号：Ｓｉ），燐（記号：Ｐ）及び硫黄（記号：Ｓ）を、該溶銑の転炉での主精錬前に予めできるだけ除去する所謂「溶銑予備処理」が行われている。そして、所謂「低燐、低硫黄」の鋼材が要求される今日では、転炉精錬のほとんどが、溶銑予備処理を経た溶銑を用いて行われている。 In recent years, in the steelmaking process, silicon (symbol: Si), phosphorus (symbol: P), and sulfur contained in the hot metal discharged from the blast furnace are used to reduce the burden of converter refining and minimize the total cost of refining. A so-called “hot metal preliminary treatment” in which (symbol: S) is removed as much as possible before the main refining of the hot metal in the converter is performed. In today's world where so-called “low phosphorus, low sulfur” steel materials are required, most converter refining is performed using hot metal that has undergone hot metal pretreatment.
そのような溶銑予備処理としては、図２に示すように、処理容器１に保持した溶銑２の中に、処理の開始より終了まで、前記インジェクションランス３を介して、酸化剤として気体酸素４及び／又は固体酸化剤（例えば、焼結鉱、製鉄ダスト、ミルスケール等の酸化鉄含有物質）５並びに石灰系造滓剤６を溶銑２中に連続的に吹き込み、溶銑の脱珪と脱燐とを行う方法がある（例えば、特許文献１及び引用文献２参照）。この場合、高炉から出銑したばかりの溶銑１は、Ｓｉを０．１〜０．６質量％、Ｐを０．０８〜０．１８質量％程度含有しており、処理の開始当初は脱珪反応が優先的に先行して起き、その後に脱燐反応が支配的になる。また、脱珪反応によってＳｉＯ２分の多いスラグ７が生成するが、該スラグ７は後に起きる脱燐反応に悪影響を与えるので、脱珪期の途中あるいは脱珪期の終了後に処理容器から排出して処理を継続するのである。ここで、固体酸化剤を吹き込むのは、酸化剤として気体酸素よりも溶銑内での分散性が良いので、脱珪反応や脱燐反応の促進に有利であり、さらに、固体酸化剤の分解が吸熱反応で、溶銑の温度を低下させ、脱燐反応が起き易くなるからである。
As such hot metal preliminary treatment, as shown in FIG. 2, in the
しかしながら、溶銑の温度は、それ以降の転炉精錬での都合や溶銑の凝固温度との兼ね合いで、無制限に低下するのは好ましくない。そこで、図３に示すように、前記インジェクションランス３とは別に、溶銑１に浸漬させない上吹きランス８を処理容器１の上方空間（フリーボードともいう）９に設け、該上吹きランス８を介して溶銑の浴面上に気体酸素を上吹きして、浴内で発生し、前記上方空間に存在するＣＯガスを所謂「２次燃焼」させ、その発生熱で溶銑温度の必要以上の低下を抑止することも行われている。
However, it is not preferable that the temperature of the hot metal be lowered indefinitely due to the convenience in the subsequent converter refining and the solidification temperature of the hot metal. Therefore, as shown in FIG. 3, apart from the
ところで、最近の製鋼工程では、環境・省エネルギーの見地より、ＣＯ２の大気放出量の低減が望まれ、転炉での鉄源としての溶銑に加える鉄スクラップ（以下、単にスクラップという）の使用量の増加が期待されている。すなわち、溶銑に比べ、スクラップの炭素含有量が格段に低いため、酸素吹錬してもＣＯ２の大気放出量が減るからである。さらに、溶銑を製造するには、高炉で還元剤としてのコークスを大量に使用する。したがって、溶銑とスクラップにすることで、コークスの使用によるＣＯ２の排出量を削減することができるからである。 By the way, in the recent steelmaking process, from the viewpoint of environment and energy saving, it is desired to reduce the amount of CO 2 released to the atmosphere, and the amount of iron scrap (hereinafter simply referred to as “scrap”) added to the hot metal as the iron source in the converter. Is expected to increase. That is, since the carbon content of scrap is much lower than that of hot metal, the amount of CO 2 released to the atmosphere is reduced even when oxygen is blown. Furthermore, in order to produce hot metal, a large amount of coke as a reducing agent is used in a blast furnace. Therefore, by using hot metal and scrap, it is possible to reduce CO 2 emission due to the use of coke.
転炉での鉄源として溶銑に加えるこのスクラップの配合量は、溶銑予備処理を行った溶銑を使用していなかった以前では、溶銑重量の１０〜１５質量％であった。しかしながら、溶銑予備処理を経た溶銑の使用が普及した今日では、該配合量は約５％程度に減少している。冷たいスクラップを溶銑へ多量投入すると、溶銑の温度が低下し過ぎるので、多量使用ができなくなっていたのである。 The amount of this scrap added to the hot metal as the iron source in the converter was 10 to 15% by mass of the hot metal weight before the hot metal subjected to the hot metal pretreatment was not used. However, today, when the use of hot metal after hot metal pretreatment has become widespread, the blending amount has decreased to about 5%. If a large amount of cold scrap was added to the hot metal, the hot metal temperature would drop too much, making it impossible to use it in large quantities.
そのため、予備処理溶銑の利用を必須とする今日では、現状よりコストをかけないで、且つ予備処理での溶銑の温度をあまり低下させずに、転炉におけるスクラップの使用量を高める技術の出現が熱望されている。
本発明は、かかる事情に鑑み、現状よりコストをかけないで、且つ予備処理での溶銑の温度をあまり低下させずに、転炉におけるスクラップの使用量を高めることの可能な溶銑予備処理方法を提供することを目的としている。 In view of such circumstances, the present invention provides a hot metal pretreatment method capable of increasing the amount of scrap used in a converter without lowering the cost of the hot metal in the pretreatment and reducing the amount of scrap in the converter. It is intended to provide.
発明者は、上記目的を達成するため鋭意研究を重ね、その成果を本発明に具現化した。すなわち、本発明は、処理容器に保持した溶銑中に、インジェクションランスを浸漬し、該インジェクションランスを介して酸化剤と石灰系造滓剤を吹き込み、該溶銑からの脱珪及び脱燐を行う溶銑の予備処理方法において、処理開始当初は、石灰系造滓剤は吹き込まずに専ら酸化剤として気体酸素だけを吹き込み、溶銑のＳｉ濃度が０．１質量％まで低下した後に、前記気体酸素に加え、固体酸化剤及び石灰系造滓剤を吹き込むと同時に、前記処理容器の上方空間に別途設けた上吹きランスを介して、該溶銑の浴面上に気体酸素を吹き付けることを特徴とする溶銑の予備処理方法である。 The inventor has intensively studied to achieve the above object, and the results have been embodied in the present invention. That is, the present invention is a hot metal in which an injection lance is immersed in hot metal held in a processing vessel, and an oxidizing agent and a lime-based fermenting agent are blown through the injection lance to perform desiliconization and dephosphorization from the hot metal. In the preliminary treatment method, at the beginning of the treatment, only the gaseous oxygen is blown as the oxidizer without blowing the lime-based faux agent, and after the Si concentration of the hot metal is reduced to 0.1% by mass, it is added to the gaseous oxygen. In addition, while blowing the solid oxidizing agent and the lime-based iron making agent, gaseous oxygen is blown onto the bath surface of the hot metal via an upper blowing lance provided separately in the upper space of the processing vessel. This is a preliminary processing method.
この場合、前記処理容器を溶銑鍋又は混銑車としたり、あるいは前記固体酸化剤を焼結鉱、製鉄ダスト及び／又はミルスケールとするのが好ましい。 In this case, it is preferable that the processing vessel is a hot metal ladle or a kneading wheel, or the solid oxidizing agent is sintered ore, iron-making dust and / or mill scale.
本発明によれば、脱Ｓｉ期に固体酸化剤を使用しないので、該固体酸化剤の吸熱分解が起きず、溶銑温度の低下が抑制でき、従来の方法に比べて、予備処理後の溶銑のＰ濃度を高めることなく、溶銑の温度を２２℃程度上昇できる。その結果、予備処理を施した溶銑を転炉に使用しても、従来の方法で予備処理した溶銑を使用した場合に比べて、製鋼プロセスにおける溶銑へのスクラップ配合比率を従来よりも２〜５％増加することが可能となる。また、脱珪期に溶銑の上に存在するスラグの塩基度（ＣａＯ／ＳｉＯ２）を従来より低下できるばかりでなく、スラグ温度の上昇により、脱珪期中及び脱珪期終了後のスラグの容器からの排滓性が向上する。その結果、以後の脱燐期で使用する塩基度調整用石灰の量が減り、その使用原単位を従来より大幅に削減できる。 According to the present invention, since no solid oxidant is used in the de-Si phase, the endothermic decomposition of the solid oxidant does not occur, and a decrease in hot metal temperature can be suppressed, compared with the conventional method, The temperature of the hot metal can be increased by about 22 ° C. without increasing the P concentration. As a result, even if the hot metal that has been pretreated is used in the converter, the ratio of scrap to the hot metal in the steelmaking process is 2 to 5 in comparison with the case of using the hot metal pretreated by the conventional method. % Can be increased. Moreover, not only can the basicity (CaO / SiO 2 ) of slag existing on the hot metal during the desiliconization period be lowered, but also a slag container during the desiliconization period and after completion of the desiliconization period due to an increase in slag temperature. Improves excretion. As a result, the amount of basicity adjusting lime to be used in the subsequent dephosphorization period is reduced, and the basic unit of use can be greatly reduced as compared with the prior art.
以下、発明をなす経緯をまじえ、本発明の最良の実施形態を説明する。 Hereinafter, the best embodiment of the present invention will be described based on the background of the invention.
発明者は、従来の溶銑予備処理方法を熱的な観点で見直し、従来技術は、溶銑の予備処理開始当初から終了まで分解吸熱する固体酸化剤を連続的に使用するものであり、脱珪期での酸素効率の点では良いが、熱損失のミニマム化という点では不十分であると結論した。そして、引き続き、対策として、既存の設備を用い、投入するエネルギーを従来より抑えて安価に溶銑予備処理を行うことができないか検討した。その結果、従来の処理開始当初の比較的反応効率の良い脱珪期を、酸化剤として気体酸素の吹き込みだけ行なっても溶銑の脱珪は十分にでき、且つ、固体酸化剤の分解顕熱による熱損失も削減できると考えた。つまり、処理開始当初は、インジェクションランスを介して気体酸素だけを溶銑中に吹き込み、溶銑のＳｉ濃度がある程度に低下した後に、前記気体酸素に加え、固体酸化剤及び石灰系造滓剤を吹き込み、脱燐を主体とした処理を行うのである。 The inventor reviewed the conventional hot metal pretreatment method from a thermal point of view, and the prior art uses a solid oxidizing agent that continuously decomposes and absorbs heat from the beginning to the end of the hot metal pretreatment. It was concluded that it was good in terms of oxygen efficiency, but it was insufficient in terms of minimizing heat loss. Then, as a countermeasure, we examined whether it was possible to perform hot metal pretreatment at low cost by using existing equipment and suppressing the input energy. As a result, even if the desiliconization period with a relatively high reaction efficiency at the beginning of the conventional treatment is performed only by blowing gaseous oxygen as the oxidizing agent, the hot metal can be sufficiently desiliconized, and by the decomposition sensible heat of the solid oxidizing agent We thought that heat loss could be reduced. That is, at the beginning of the treatment, only gaseous oxygen is blown into the hot metal via the injection lance, and after the Si concentration of the hot metal is lowered to some extent, in addition to the gaseous oxygen, a solid oxidizing agent and a lime-based slagging agent are blown. A process mainly including dephosphorization is performed.
そこで、発明者は、このインジェクションランスを介して気体酸素だけを溶銑中に吹き込む適切な期間を見出すため、気体酸素だけを溶銑中に吹き込む実験を行い、図１に示すような脱珪効率についてのデータを得た。ここで、脱珪効率は下式で定義されるものである。 Therefore, the inventor conducted an experiment in which only gaseous oxygen was blown into the hot metal in order to find an appropriate period in which only gaseous oxygen was blown into the hot metal through this injection lance, and the desiliconization efficiency as shown in FIG. I got the data. Here, the desiliconization efficiency is defined by the following equation.
脱Ｓｉ効率（％）＝［脱Ｓｉ量からの理論酸素量（ｍ３（標準状態））／供給酸素量（ｍ３（標準状態））］×１００
図１によれば、気体酸素だけの吹込みで、溶銑のＳｉ濃度は、０．１質量％まで低下すると上記脱珪効率が急激に低下してくる。そこで、発明者は、前記気体酸素だけを溶銑中に吹き込む期間を溶銑のＳｉ濃度が０．１質量％までの期間と定めることにしたのである。なお、このような溶銑の脱珪効率が急激に低下してくる時期は、気体酸素を吹き込む対象となる溶銑の組成（特にＳｉ濃度）や温度、気体酸素の吹き込み流量等の処理条件に依存して変化する。しかしながら、多くの実験結果に基づくと、実際に予備処理される条件下では、気体酸素だけを溶銑中に吹き込む期間を溶銑のＳｉ濃度：０．１質量％として十分であることが確認できた。
Si removal efficiency (%) = [theoretical oxygen amount from de-Si amount (m 3 (standard state)) / amount of supplied oxygen (m 3 (standard state))] × 100
According to FIG. 1, the desiliconization efficiency is drastically lowered when the Si concentration of the hot metal is reduced to 0.1 mass% by blowing only gaseous oxygen. Therefore, the inventor has decided that the period in which only the gaseous oxygen is blown into the hot metal is a period in which the Si concentration of the hot metal is up to 0.1% by mass. The time when the desiliconization efficiency of the hot metal rapidly decreases depends on the processing conditions such as the composition (particularly Si concentration) and temperature of the hot metal to which gaseous oxygen is blown and the flow rate of blown gaseous oxygen. Change. However, based on the results of many experiments, it was confirmed that, under the conditions of actual pretreatment, it was sufficient to set the period of blowing only gaseous oxygen into the hot metal as the Si concentration of hot metal: 0.1% by mass.
次に、発明者は、処理開始当初は、インジェクションランスを介して気体酸素だけを溶銑中に吹き込み、溶銑のＳｉ濃度がある程度に低下した後に、前記気体酸素に加え、固体酸化剤及び石灰系造滓剤として生石灰を吹き込み、脱燐を主体とした処理を行った場合に脱燐の起きる程度が、前記した従来の方法（図２参照）で予備処理した場合に比べてどのようになるかを検討した。 Next, at the beginning of the treatment, the inventor blows only gaseous oxygen into the hot metal via an injection lance, and after the Si concentration in the hot metal is lowered to some extent, in addition to the gaseous oxygen, a solid oxidizing agent and a lime-based structure are added. When quick lime is blown as a glaze and a process mainly including dephosphorization is performed, the degree of dephosphorization will be compared to the case of the pretreatment by the conventional method (see FIG. 2) described above. investigated.
その結果、図４に示すように、脱燐量に対する溶銑温度の降下量が削減された。また、本方法において、発明者は、溶銑のＳｉ濃度が０．０１質量％を下回った時期に、従来から行われている「処理容器の上方空間に別途設けた上吹きランスを介して、該溶銑の浴面上に気体酸素を吹き付け、上方空間に存在するＣＯを二次燃焼して、その熱を溶鋼に着熱する」技術をも採用することにした。脱珪反応の終了後から脱炭反応が活発になるので、所謂「二次燃焼」による効果は十分に得られるからである。 As a result, as shown in FIG. 4, the amount of decrease in hot metal temperature relative to the amount of dephosphorization was reduced. In addition, in the present method, when the Si concentration of the hot metal falls below 0.01% by mass, the inventor has conventionally performed “through an upper blowing lance separately provided in the upper space of the processing vessel, It was also decided to adopt the technology of spraying gaseous oxygen on the bath surface of the molten iron, secondary combustion of the CO present in the upper space, and radiating the heat to the molten steel. This is because the decarburization reaction becomes active after the desiliconization reaction is completed, so that the effect of so-called “secondary combustion” can be sufficiently obtained.
そして、この二次燃焼を伴う実験を行ったところ、処理後の溶銑温度が従来法による場合に比べて約２２℃上昇し、脱燐程度が低下することもなかったので、この方法を本発明としたのである。つまり、従来技術から、処理中に溶銑への気体酸素の供給方法だけを変化させ、処理中の溶銑温度の低下をミニマム化したのである。また、脱珪期に固体酸化剤を使用しないため、該固体酸化剤に含有される石灰分が浴に供給されない。そのため、脱珪期の終了後に存在するスラグは、従来よりも低塩基度となり、さらに温度が高いので、処理容器からの排出（排滓性という）し易くなる。その結果、脱燐期に形成されるスラグの量も少なくなり、吹き込む塩基度調整用の生石灰の使用量が削減できる。 Then, when an experiment involving this secondary combustion was conducted, the hot metal temperature after the treatment increased by about 22 ° C. compared to the conventional method, and the degree of dephosphorization did not decrease. It was. That is, from the prior art, only the method of supplying gaseous oxygen to the hot metal during the process is changed, and the decrease in the hot metal temperature during the process is minimized. Further, since no solid oxidizer is used during the desiliconization period, the lime content contained in the solid oxidizer is not supplied to the bath. For this reason, the slag present after the end of the desiliconization period has a lower basicity than that of the conventional slag, and the temperature is higher, so that it is easy to discharge from the processing container (referred to as exhaustability). As a result, the amount of slag formed during the dephosphorization period is reduced, and the amount of quick lime used for adjusting the basicity to be blown can be reduced.
このような本発明を実施する処理容器としては、溶銑の搬送に利用する既存の溶銑鍋又は混銑車とするのが好ましい。従来よりの処理実績があり、経済的に有利だからである。また、固体酸化剤としては、酸化鉄を含有する物質であれば特に限定しないが、製鉄所で入手し易く、安価なので、焼結鉱、製鉄ダスト、ミルスケ−ルの利用で十分である。なお、石灰系造滓剤としては、公知の石灰系造滓剤である生石灰単味、若しくは生石灰を主体とし、これに石灰石（ＣａＣＯ３）や蛍石（ＣａＦ２）を加えたものが使用できる。 As such a processing container for carrying out the present invention, it is preferable to use an existing hot metal ladle or a kneading car used for conveying hot metal. This is because there is a past processing result and it is economically advantageous. Further, the solid oxidizing agent is not particularly limited as long as it is a substance containing iron oxide. However, since it is easily available at an iron mill and is inexpensive, it is sufficient to use sintered ore, iron-making dust, and mill scale. As the lime slag agent, quick lime is known lime slag agent plain or mainly quicklime, limestone (CaCO 3) and fluorite (CaF 2) can be used that additionally .
高炉から出銑したばかりの３５０トンの溶銑を、収容能力４５０トンの混銑車に受け、既存の予備処理設備（図３参照、インジェクションランス及び上吹きランスを使用する）を利用して従来方法（図５参照）及び本発明に係る方法で溶銑の予備処理を行った。なお、本発明に係る方法の実施に際しては、固体酸化剤として焼結鉱を４５ｋｇ／ｔ−溶銑、脱燐剤に生石灰を３ｋｇ／ｔ−溶銑使用した。また、気体酸素は、全期間を通じて１０〜３０ｍ３（標準状態）／ｍｉｎの一定量を吹き込み、上吹きランスからの二次燃焼用気体酸素の流量は、２０〜３０ｍ３（標準状態）／ｍｉｎとした。さらに、溶銑のＳｉ濃度がほぼ０．１０質量％になることの判断を、処理中のスラグフォーミングの程度（フォーミングしたスラグの高さ）を目視観察することで行った。溶銑中のＳｉ濃度が０．１０質量％以下に低下すると、供給された酸素が溶銑中のＣを酸化し、ＣＯガスの発生が活発となる。このため、急激にスラグがフォーミングし始めるので、フォーミング高さの急増をもって溶銑中のＳｉ濃度がほぼ０．１０質量％に到達したことを知り得るのである。 The 350 ton hot metal just released from the blast furnace is received in a kneading car with a capacity of 450 ton, and the existing method (see Fig. 3, using injection lance and top blowing lance) is used to make the conventional method ( 5) and a hot metal pretreatment by the method according to the present invention. In carrying out the method according to the present invention, 45 kg / t-hot metal sinter was used as the solid oxidizing agent, and 3 kg / t-hot metal was used as the dephosphorizing agent. Further, gaseous oxygen is blown in a certain amount of 10 to 30 m 3 (standard state) / min throughout the entire period, and the flow rate of the gaseous oxygen for secondary combustion from the top blowing lance is 20 to 30 m 3 (standard state) / min. It was. Further, the determination that the Si concentration in the hot metal was approximately 0.10% by mass was made by visually observing the degree of slag forming during processing (the height of the formed slag). When the Si concentration in the hot metal decreases to 0.10% by mass or less, the supplied oxygen oxidizes C in the hot metal and the generation of CO gas becomes active. For this reason, since the slag begins to form suddenly, it can be known that the Si concentration in the hot metal has reached approximately 0.10% by mass with the rapid increase of the forming height.
実施結果を、処理前後の溶銑の組成、溶銑温度及び脱珪期に排出したスラグの量で評価し、表１及び図６に一括して示す。 The results of the evaluation were evaluated by the composition of the hot metal before and after the treatment, the hot metal temperature, and the amount of slag discharged during the desiliconization period, and are collectively shown in Table 1 and FIG.
表１より、本発明によれば、すべての実施例で従来技術による場合に比べて、処理後の溶銑温度が２２℃上昇し、溶銑の燐濃度も０．００７質量％だけ低下していることが明らかである。また、図６より、排滓量は、本発明の実施で増加することも明らかである。さらに、スクラップの使用比率を従来より２〜５％増加させることができた。 From Table 1, according to the present invention, the hot metal temperature after the treatment increased by 22 ° C. and the phosphorus concentration of the hot metal decreased by 0.007% by mass in all the examples as compared with the case of the prior art. Is clear. It is also clear from FIG. 6 that the amount of excretion increases with the implementation of the present invention. In addition, the scrap usage rate could be increased by 2-5%.
１ 処理容器（混銑車）
２ 溶銑
３ インジェクションランス
４ 気体酸素
５ 固体酸化剤
６ 石灰系造滓剤
７ スラグ
８ 上吹きランス
９ フリーボード
1 Processing container (chaos car)
2
Claims (3)
処理開始当初は、石灰系造滓剤は吹き込まずに専ら酸化剤として気体酸素だけを吹き込み、溶銑のＳｉ濃度が０．１質量％まで低下した後に、前記気体酸素に加え、固体酸化剤及び石灰系造滓剤を吹き込むと同時に、前記処理容器の上方空間に別途設けた上吹きランスを介して、該溶銑の浴面上に気体酸素を吹き付けることを特徴とする溶銑の予備処理方法。 In the hot metal pretreatment method of immersing an injection lance in hot metal held in a processing vessel, blowing an oxidizing agent and a lime-based iron making agent through the injection lance, and performing desiliconization and dephosphorization from the hot metal,
At the beginning of the treatment, only gaseous oxygen is blown exclusively as an oxidizing agent without blowing a lime-based molding agent, and after the Si concentration in the hot metal is reduced to 0.1% by mass, in addition to the gaseous oxygen, a solid oxidizing agent and lime A hot metal pretreatment method characterized in that gaseous oxygen is blown onto the bath surface of the hot metal via an upper blow lance separately provided in the upper space of the processing vessel at the same time as the system iron making agent is blown.
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