JP4927467B2 - CaO-based desulfurizing agent and method for desulfurizing molten iron - Google Patents

CaO-based desulfurizing agent and method for desulfurizing molten iron Download PDF

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JP4927467B2
JP4927467B2 JP2006208042A JP2006208042A JP4927467B2 JP 4927467 B2 JP4927467 B2 JP 4927467B2 JP 2006208042 A JP2006208042 A JP 2006208042A JP 2006208042 A JP2006208042 A JP 2006208042A JP 4927467 B2 JP4927467 B2 JP 4927467B2
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雄太 日野
由枝 中井
郁宏 鷲見
誠司 鍋島
友紀 草間
信孝 中山
山口  篤
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Jfeスチール株式会社
Jfeミネラル株式会社
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Description

本発明は、溶鉄の脱硫処理に使用するCaO系脱硫剤及びそれを用いた溶鉄の脱硫処理方法に関するものである。   The present invention relates to a CaO-based desulfurization agent used for molten iron desulfurization and a method for desulfurizing molten iron using the same.
近年、鋼の高純度化に対する要求が従来にも増して強くなり、これに伴って鋼中の不純物を除去する技術開発が盛んに行われている。今日の鋼の精錬プロセスにおいては、転炉での脱炭精錬工程に先立って溶銑に含有される燐及び硫黄を除去する工程、即ち溶銑予備処理工程が一般的に行われている。また、溶銑段階での脱燐処理及び脱硫処理のみでは所望する成分濃度まで安定して低下できない場合には、転炉をはじめとする製鋼炉より出湯した溶鋼においても、脱燐処理や脱硫処理が行われている。製鋼炉から出湯された溶鋼における脱燐処理及び脱硫処理を、それぞれ溶鋼脱燐、溶鋼脱硫と称している。尚、本発明では溶銑及び溶鋼をまとめて溶鉄と称している。   In recent years, the demand for higher purity of steel has become stronger than ever, and in accordance with this, technological development for removing impurities in steel has been actively conducted. In today's steel refining process, prior to the decarburization refining process in the converter, a process of removing phosphorus and sulfur contained in the hot metal, that is, a hot metal pretreatment process is generally performed. In addition, when only the dephosphorization treatment and desulfurization treatment at the hot metal stage cannot be stably reduced to the desired component concentration, dephosphorization treatment and desulfurization treatment can be performed even in molten steel discharged from a steelmaking furnace including a converter. Has been done. Dephosphorization treatment and desulfurization treatment in molten steel discharged from a steelmaking furnace are referred to as molten steel dephosphorization and molten steel desulfurization, respectively. In the present invention, hot metal and molten steel are collectively referred to as molten iron.
このうち、溶銑及び溶鋼における脱硫処理、つまり溶鉄の脱硫処理には、脱硫剤として石灰(以下、「CaO」と記す)粉を主成分とする脱硫剤、カルシウムカーバイド(CaC2 )粉、カルシウムアルミネート(mCaO・nAl23)、金属Mgなどが使用されているが、安価であることから、近年ではCaO粉を主成分とする脱硫剤が広く用いられている。このCaO系脱硫剤による脱硫反応は、「CaO+[S]→(CaS)+[O]」に示される反応式に基づいて進行する。ここで、[S]は溶鉄中の硫黄、(CaS)はスラグ中のCaS、[O]は溶鉄中の酸素を表している。 Among these, for desulfurization treatment of hot metal and molten steel, that is, desulfurization treatment of molten iron, a desulfurization agent mainly composed of lime (hereinafter referred to as “CaO”) powder, calcium carbide (CaC 2 ) powder, calcium aluminum. Nate (mCaO · nAl 2 O 3 ), metallic Mg, and the like are used, but since they are inexpensive, desulfurization agents mainly composed of CaO powder have been widely used in recent years. The desulfurization reaction by the CaO-based desulfurization agent proceeds based on the reaction formula shown by “CaO + [S] → (CaS) + [O]”. Here, [S] represents sulfur in the molten iron, (CaS) represents CaS in the slag, and [O] represents oxygen in the molten iron.
上記脱硫反応式を進める方策として、溶鉄中の酸素ポテンシャルを低下すること、及び脱硫剤の滓化を促進させることなどが挙げられており、このため、CaO系の脱硫剤には、滓化を促進する目的でフッ化カルシウム(CaF2 )などの滓化促進剤が少量添加されている。しかし、近年、フッ素の環境への影響が問題視されており、フッ素を使用しないCaO系脱硫剤の開発が望まれている。 Measures to advance the desulfurization reaction formula include reducing the oxygen potential in the molten iron and promoting the hatching of the desulfurizing agent. For this reason, the CaO-based desulfurizing agent has not been hatched. A small amount of a hatching accelerator such as calcium fluoride (CaF 2 ) is added for the purpose of promotion. However, in recent years, the influence of fluorine on the environment has been regarded as a problem, and the development of a CaO-based desulfurization agent that does not use fluorine is desired.
一方、溶鉄の脱硫反応速度を高めるには、脱硫剤の種類に拘らず、溶鉄/脱硫剤間の反応界面積を増加させることが効果的であり、従って、脱硫剤の粒径は細かいほど望ましい。但し、CaO系脱硫剤の主成分であるCaO粉末は、溶鉄とは濡れ難い性質を有するため、細粒化しても溶鉄に添加されたCaO粉末は互いに凝集してしまい、溶鉄/脱硫剤間の反応界面積の増加に寄与せず、凝集内部のCaOは未反応のままであるために反応効率が向上しないといった問題が生じる。   On the other hand, in order to increase the desulfurization reaction rate of molten iron, it is effective to increase the reaction interface area between the molten iron and the desulfurization agent regardless of the type of desulfurization agent. . However, since the CaO powder, which is the main component of the CaO-based desulfurizing agent, has a property that it is difficult to wet with molten iron, the CaO powder added to the molten iron aggregates even if it is finely divided, and between the molten iron / desulfurizing agent. There is a problem that the reaction efficiency is not improved because CaO inside the aggregate does not contribute to increase of the reaction interface area and remains unreacted.
これらのことから、CaO系脱硫剤を用いて溶鉄を効率的に脱硫処理するためには、添加したCaO粉体の凝集を抑制してCaO系脱硫剤を細かいままの状態で溶鉄中へ侵入させ、溶鉄浴内での分散を促進させて、反応界面積を増加させることが有効であると考えられる。   For these reasons, in order to efficiently desulfurize molten iron using a CaO-based desulfurizing agent, the aggregation of the added CaO powder is suppressed and the CaO-based desulfurizing agent is allowed to enter the molten iron in a fine state. It is considered effective to increase the reaction interface area by promoting dispersion in the molten iron bath.
これを実現させる技術として、特許文献1には、CaO系脱硫剤において、CaO粒子の表面の全部または一部に、SiC粒子または黒鉛粒子を付着させ、溶鉄と脱硫剤との濡れ性を向上させ、CaO粉体の凝集を抑制して脱硫反応を促進させる技術が提案されている。そして、特許文献1では、好適なサイズのCaO粒子は、平均粒径が100〜150μmのものであり、また、好適なサイズのSiC粒子または黒鉛粒子は、平均粒径が5〜10μmのものであることを提案している。
特開2004−124120号公報
As a technique for realizing this, Patent Document 1 discloses that in a CaO-based desulfurization agent, SiC particles or graphite particles are attached to all or a part of the surface of CaO particles, thereby improving the wettability between the molten iron and the desulfurization agent. In addition, a technique for suppressing the aggregation of CaO powder and promoting the desulfurization reaction has been proposed. And in patent document 1, the suitable size CaO particle | grain is a thing with an average particle diameter of 100-150 micrometers, and the suitable size SiC particle or graphite particle | grain is a thing with an average particle diameter of 5-10 micrometers. Propose that there is.
JP 2004-124120 A
しかしながら、特許文献1は、経済的な理由から、つまり製造コストを抑えるために、SiC粒子及び黒鉛粒子の好ましい平均粒径として5〜10μmを挙げており、この平均粒径のSiC粒子及び黒鉛粒子は、表面に付着層を形成するための粒子としては粒径が大き過ぎ、CaO粒子の表面に付着し難いという問題がある。そのために、特許文献1では、樹脂系の有機溶剤を粘結剤として使用しており、粘結剤を用いて強制的に付着させることから、12質量%程度のSiC粒子または黒鉛粒子が必要になり(段落[0021]参照)、その結果、多量のSiC粒子または黒鉛粒子が必要である、粘結剤が必要である、粘結剤を添加する必要上から脱硫剤の製造工程が煩雑になるなど、脱硫剤の製造コストが高くなるという問題がある。   However, Patent Document 1 lists 5 to 10 μm as a preferable average particle size of SiC particles and graphite particles for economic reasons, that is, to suppress the manufacturing cost, and SiC particles and graphite particles having this average particle size. Has a problem that the particle size is too large as a particle for forming an adhesion layer on the surface, and it is difficult to adhere to the surface of the CaO particle. Therefore, in patent document 1, since the resin-type organic solvent is used as a binder and it is made to adhere forcibly using a binder, about 12 mass% SiC particle or graphite particle is needed. As a result (see paragraph [0021]), as a result, a large amount of SiC particles or graphite particles are required, a binder is required, and the manufacturing process of the desulfurizing agent is complicated due to the necessity of adding the binder. There is a problem that the manufacturing cost of the desulfurizing agent becomes high.
本発明は上記事情に鑑みてなされたもので、その目的とするところは、簡便に製造可能で且つ高効率の脱硫処理を可能とする、溶鉄との濡れ性を向上させたCaO系脱硫剤を提供するとともに、その脱硫剤を用いた溶鉄の脱硫処理方法を提供することである。   The present invention has been made in view of the above circumstances. The object of the present invention is to provide a CaO-based desulfurization agent with improved wettability with molten iron, which can be easily manufactured and enables highly efficient desulfurization treatment. And providing a method for desulfurization of molten iron using the desulfurizing agent.
上記課題を解決するための第1の発明に係るCaO系脱硫剤は、主成分がCaO粒子であるCaO系脱硫剤において、前記CaO粒子の平均粒径は10μm以上であり、平均粒径が5μm以下である、主成分を炭素とする炭素質粒子を、前記CaO粒子と混合させたものであることを特徴とするものである。 The CaO-based desulfurization agent according to the first invention for solving the above problems is a CaO-based desulfurization agent whose main component is CaO particles, wherein the average particle diameter of the CaO particles is 10 μm or more, and the average particle diameter is 5 μm. The following carbonaceous particles whose main component is carbon are mixed with the CaO particles.
第2の発明に係るCaO系脱硫剤は、第1の発明において、前記炭素質粒子の平均粒径は1μm以下であることを特徴とするものである。   The CaO-based desulfurizing agent according to the second invention is characterized in that, in the first invention, the carbonaceous particles have an average particle size of 1 μm or less.
の発明に係るCaO系脱硫剤は、第1または第2の発明において、前記CaO系脱硫剤における前記炭素質粒子の配合率は1質量%以上であることを特徴とするものである。 The CaO-based desulfurizing agent according to the third invention is characterized in that, in the first or second invention , the blending ratio of the carbonaceous particles in the CaO-based desulfurizing agent is 1% by mass or more.
の発明に係るCaO系脱硫剤は、第1ないし第の発明の何れかにおいて、前記CaO系脱硫剤は、CaOと反応して低融点化合物を形成する物質を含有することを特徴とするものである。 CaO-based desulfurizing agent according to the fourth invention, in any one of the first to third aspects, the CaO-based desulfurizing agent, and characterized in that it contains a substance which reacts with CaO to form a low melting compound To do.
の発明に係るCaO系脱硫剤は、第1ないし第の発明の何れかにおいて、前記CaO系脱硫剤は、フッ素を含有しないことを特徴とするものである。 A CaO-based desulfurizing agent according to a fifth invention is characterized in that, in any of the first to fourth inventions, the CaO-based desulfurizing agent does not contain fluorine.
の発明に係るCaO系脱硫剤は、第1ないし第の発明の何れかにおいて、前記CaO系脱硫剤は、脱酸のための金属物質を含有することを特徴とするものである。 CaO-based desulfurizing agent according to the sixth invention, in any one of the first to fifth invention, the CaO-based desulfurizing agent is characterized in that it contains a metal material for deoxidation.
の発明に係る溶鉄の脱硫処理方法は、処理容器内に収容された溶鉄に、第1ないし第の発明の何れか1つに記載された脱硫剤を添加して脱硫処理することを特徴とするものである。 According to a seventh aspect of the present invention, there is provided a method for desulfurizing a molten iron, comprising adding the desulfurizing agent described in any one of the first to sixth inventions to the molten iron accommodated in a processing vessel. It is a feature.
の発明に係る溶鉄の脱硫処理方法は、第の発明において、前記脱硫剤を、溶鉄の浴面上方から上置き添加することを特徴とするものである。 The desulfurization treatment method for molten iron according to an eighth invention is characterized in that, in the seventh invention, the desulfurizing agent is added from above the bath surface of the molten iron.
の発明に係る溶鉄の脱硫処理方法は、第の発明において、前記脱硫剤を、上吹きランスを介して搬送用ガスとともに溶鉄浴面に吹き付けて添加することを特徴とするものである。 According to a ninth aspect of the present invention, there is provided a desulfurization treatment method for molten iron according to the seventh aspect of the present invention, wherein the desulfurizing agent is sprayed and added to the molten iron bath surface along with a carrier gas through an upper blowing lance. .
10の発明に係る溶鉄の脱硫処理方法は、第の発明において、前記脱硫剤を、浸漬ランスを介して搬送ガスとともに溶鉄浴中に吹き込んで添加することを特徴とするものである。 According to a tenth aspect of the present invention, there is provided a desulfurization treatment method for molten iron according to the seventh aspect , wherein the desulfurizing agent is blown into a molten iron bath together with a carrier gas via an immersion lance.
11の発明に係る溶鉄の脱硫処理方法は、第ないし第10の発明の何れかにおいて、前記処理容器に収容された溶鉄を、攪拌羽根によって攪拌しながら脱硫処理することを特徴とするものである。 The method for desulfurizing a molten iron according to an eleventh invention is characterized in that in any of the seventh to tenth inventions, the molten iron accommodated in the processing vessel is desulfurized while being stirred by a stirring blade. It is.
本発明によれば、付着させる炭素質粒子の平均粒径が5μm以下、好ましくは1μm以下であるので、粘結剤などを使用しなくてもCaO粒子と混合するだけでCaO粒子の表面に炭素質粒子を付着させることができる。また、粘結剤を使用していないので、粘結剤を使用した場合と比較して薄い付着層がCaO粒子の表面に均一に形成され、そのために、少ない炭素質粒子の使用量で付着層を形成でき、また、粘結剤などを使用することなく混合するだけで製造可能であり、製造方法が簡単であることから、製造コストを抑えることができる。そして、CaO粒子表面に付着した炭素質粒子により、CaO系脱硫剤と溶鉄との濡れ性が向上し、添加したCaO粒子の凝集が抑制されてCaO粒子を細かいままの状態で溶鉄中に侵入且つ分散させることができるので、脱硫反応界面積が増加して効率的に脱硫処理することができる。また、脱硫効率が高いので、滓化促進剤であるフッ素源を添加する必要がない。   According to the present invention, since the average particle size of the carbonaceous particles to be adhered is 5 μm or less, preferably 1 μm or less, carbon can be formed on the surface of the CaO particles only by mixing with the CaO particles without using a binder or the like. Particles can be attached. In addition, since no binder is used, a thin adhesion layer is uniformly formed on the surface of the CaO particles as compared with the case where a binder is used. For this reason, the adhesion layer is used with a small amount of carbonaceous particles. In addition, it can be produced simply by mixing without using a binder or the like, and since the production method is simple, the production cost can be reduced. The carbonaceous particles attached to the surface of the CaO particles improve the wettability between the CaO-based desulfurization agent and the molten iron, and the aggregation of the added CaO particles is suppressed and the CaO particles enter the molten iron in a fine state and Since it can be dispersed, the desulfurization reaction interfacial area is increased and the desulfurization treatment can be performed efficiently. Further, since the desulfurization efficiency is high, it is not necessary to add a fluorine source which is a hatching accelerator.
以下、本発明を具体的に説明する。   Hereinafter, the present invention will be specifically described.
CaO系脱硫剤を用いて溶鉄を脱硫処理する場合、前述したように、CaO系脱硫剤の主成分であるCaO粒子と溶鉄とは濡れ難く、溶鉄に添加されたCaO粉体は互いに凝集してしまう。つまり、CaO系脱硫剤による溶鉄の脱硫反応を促進させるためには、溶鉄とCaO粉体との濡れ性を向上させ、添加するCaO粉体の凝集を抑制し、CaO粉体を細かい状態で溶鉄中に侵入させ、分散を促進して反応界面積を増加させることが有効である。溶鉄とCaO粒子との接触角は130〜137°という報告があり、この接触角を低減させることが必要である。   When the molten iron is desulfurized using the CaO-based desulfurizing agent, as described above, the CaO particles that are the main components of the CaO-based desulfurizing agent and the molten iron are difficult to wet, and the CaO powder added to the molten iron aggregates with each other. End up. That is, in order to promote the desulfurization reaction of the molten iron by the CaO-based desulfurizing agent, the wettability between the molten iron and the CaO powder is improved, the aggregation of the added CaO powder is suppressed, and the CaO powder is finely molten. It is effective to increase the reaction interfacial area by penetrating into it and promoting dispersion. It has been reported that the contact angle between molten iron and CaO particles is 130 to 137 °, and it is necessary to reduce this contact angle.
そこで、本発明者等は、溶鉄とCaOとの濡れ性を向上させる物質として溶鉄との接触角が約55°であり、CaOに比べてはるかに接触角の低い炭素に着目し、この炭素を用いて比較的簡単な方法で濡れ性を向上させることについて、種々調査・検討を行った。   Therefore, the present inventors have focused on carbon having a contact angle with molten iron of about 55 ° as a substance that improves the wettability between molten iron and CaO, and has a much lower contact angle than CaO. Various investigations and studies were conducted on improving wettability by using a relatively simple method.
先ず、CaO系脱硫剤の主成分である、平均粒径がおよそ40μmのCaO粉体に種々のサイズの炭素質粒子を添加し、CaO粉体と炭素質粒子とを攪拌・混合した。CaO粉体と炭素質粒子とを攪拌・混合した後、サンプルを採取して顕微鏡を用いてCaO粒子及び炭素質粒子の分布状況を観察・調査した。ここで、炭素質粒子とは、主成分が炭素である粒子であり、カーボンブラック粒子、コークス粒子、石炭粒子、木炭粒子、黒鉛粒子などである。   First, carbonaceous particles of various sizes were added to CaO powder having an average particle size of about 40 μm, which is the main component of the CaO-based desulfurizing agent, and the CaO powder and carbonaceous particles were stirred and mixed. After stirring and mixing the CaO powder and the carbonaceous particles, a sample was collected, and the distribution state of the CaO particles and the carbonaceous particles was observed and investigated using a microscope. Here, the carbonaceous particles are particles whose main component is carbon, such as carbon black particles, coke particles, coal particles, charcoal particles, and graphite particles.
その結果、平均粒径が5μm以下の炭素質粒子を添加した場合に、CaO粒子の表面近傍に炭素質粒子が数多く存在していることが観察された。特に、平均粒径が1μm以下の炭素質粒子を添加した場合に、その傾向が顕著であることが観察された。これに対して、平均粒径が5μmを超える炭素質粒子を添加した場合には、CaO粒子と炭素質粒子とは独立して存在していることが観察された。即ち、CaO系脱硫剤の主成分であるCaO粉体に平均粒径が5μm以下の炭素質粒子を添加し、混合することで、溶鉄とCaO系脱硫剤との濡れ性が向上し、脱硫反応が促進する可能性を見出した。   As a result, when carbonaceous particles having an average particle diameter of 5 μm or less were added, it was observed that many carbonaceous particles were present near the surface of the CaO particles. In particular, when carbonaceous particles having an average particle size of 1 μm or less were added, it was observed that the tendency was remarkable. On the other hand, when carbonaceous particles having an average particle size exceeding 5 μm were added, it was observed that CaO particles and carbonaceous particles exist independently. That is, by adding and mixing carbonaceous particles having an average particle size of 5 μm or less to CaO powder, which is the main component of CaO-based desulfurizing agent, the wettability between molten iron and CaO-based desulfurizing agent is improved, and desulfurization reaction is performed. Found the possibility to promote.
そこで、溶銑を用いた小型規模の脱硫実験を行い、溶銑の脱硫挙動について調査した。図1に、攪拌羽根(「インペラー」ともいう)を備えた機械攪拌式脱硫装置を模擬した実験装置の概略図を示す。実験装置7は高周波加熱コイル10を備えており、坩堝容器9に保持された溶銑3に攪拌羽根4を浸漬させ、電動機8により攪拌羽根4を回転させ、溶銑3の撹拌を行いながら、溶銑3の浴面上に脱硫剤を一括上置き添加して脱硫処理した。脱硫剤としては、(1):CaO粉体に平均粒径が5μm以下の炭素質粒子を添加したもの、(2):CaO粉体に平均粒径が10μm以上の炭素質粒子を添加したもの、及び、(3):CaO粉単体のみの合計3種類の脱硫剤を使用した。CaO粉体の平均粒径は40μmとし、炭素質物質としてはカーボンブラックを用い、カーボンブラックの配合率は4質量%とした。また、脱硫剤の添加量は溶銑トン当たり5kg(以下「kg/t」と記す)とした。脱硫処理中、所定時間毎に溶銑のサンプリングを行い、脱硫挙動を調査した。   Therefore, a small-scale desulfurization experiment using hot metal was conducted to investigate the desulfurization behavior of hot metal. FIG. 1 shows a schematic diagram of an experimental apparatus simulating a mechanical stirring type desulfurization apparatus provided with a stirring blade (also referred to as “impeller”). The experimental apparatus 7 includes a high-frequency heating coil 10. The stirring blade 4 is immersed in the hot metal 3 held in the crucible container 9, the stirring blade 4 is rotated by the electric motor 8, and the hot metal 3 is stirred. A desulfurizing agent was placed on the bath surface and added to the desulfurization treatment. As the desulfurization agent, (1): CaO powder added with carbonaceous particles having an average particle size of 5 μm or less, (2): CaO powder added with carbonaceous particles having an average particle size of 10 μm or more And (3): A total of three types of desulfurization agents consisting of only CaO powder were used. The average particle diameter of the CaO powder was 40 μm, carbon black was used as the carbonaceous material, and the blending ratio of carbon black was 4 mass%. The amount of desulfurizing agent added was 5 kg per ton of hot metal (hereinafter referred to as “kg / t”). During the desulfurization process, hot metal was sampled at predetermined intervals to investigate the desulfurization behavior.
図2に、実験装置における脱硫処理での溶銑中の硫黄濃度の推移を脱硫剤の種類別に比較して示す。図2に示すように、CaO粉体と平均粒径が5μm以下の炭素質粒子とを混合した脱硫剤を使用することで、脱硫反応は格段に効率化されることが分かった。   In FIG. 2, the transition of the sulfur concentration in the hot metal in the desulfurization treatment in the experimental apparatus is shown in comparison with the type of desulfurizing agent. As shown in FIG. 2, it was found that the desulfurization reaction was remarkably improved by using a desulfurization agent in which CaO powder and carbonaceous particles having an average particle diameter of 5 μm or less were used.
この結果から、CaO粉体に平均粒径が5μm以下の炭素質粒子を混合した場合、CaO粒子は、その表面近傍に炭素質粒子が存在した状態で溶鉄中に侵入することが確認できた。このとき、炭素質粒子と溶鉄との濡れ性は良好であるので、CaO系脱硫剤は凝集せず、微細な状態で溶鉄中に侵入する。つまり、CaO系脱硫剤の使用原単位が同じであっても、脱硫剤が凝集せずに微細な状態で溶鉄中に侵入するので、反応界面積が増加して脱硫反応が促進される。   From this result, it was confirmed that when the carbonaceous particles having an average particle size of 5 μm or less were mixed with the CaO powder, the CaO particles penetrated into the molten iron with the carbonaceous particles present in the vicinity of the surface. At this time, since the wettability between the carbonaceous particles and the molten iron is good, the CaO-based desulfurizing agent does not aggregate and penetrates into the molten iron in a fine state. That is, even if the basic unit of use of the CaO-based desulfurizing agent is the same, the desulfurizing agent does not aggregate and enters the molten iron in a fine state, so that the reaction interfacial area increases and the desulfurization reaction is promoted.
以上の結果から、CaO系脱硫剤に混合する炭素質粒子の平均粒径は5μm以下とする必要のあることが分かった。更に試験を実施した結果、炭素質粒子の平均粒径を1μm以下とすることで、脱硫反応は更に促進されることが確認できた。この場合、CaO粒子の表面近傍に炭素質粒子を安定して存在させる観点から、CaO系脱硫剤の主成分であるCaO粒子の平均粒径は炭素質粒子の平均粒径よりも大きくしなければならず、また、CaO粒子の平均粒径と炭素質粒子の平均粒径との差は大きいほど好ましい。具体的には、CaO粒子の平均粒径は10μm以上であることが好ましい。これは、CaO粒子と炭素質粒子との粒径差が小さくなり過ぎると、CaO粒子の表面に炭素質粒子が接することはなく、それぞれが独立して存在するからである。但し、CaO粒子を大きくし過ぎると、反応界面積は小さくなるので、CaO粒子の平均粒径は300μm以下であることが望ましい。   From the above results, it was found that the average particle size of the carbonaceous particles mixed with the CaO-based desulfurizing agent needs to be 5 μm or less. As a result of further tests, it was confirmed that the desulfurization reaction was further promoted by setting the average particle size of the carbonaceous particles to 1 μm or less. In this case, from the viewpoint of stably presenting the carbonaceous particles in the vicinity of the surface of the CaO particles, the average particle size of the CaO particles as the main component of the CaO-based desulfurizing agent must be larger than the average particle size of the carbonaceous particles. Moreover, the difference between the average particle diameter of CaO particles and the average particle diameter of carbonaceous particles is preferably as large as possible. Specifically, the average particle diameter of the CaO particles is preferably 10 μm or more. This is because if the difference in particle size between the CaO particles and the carbonaceous particles becomes too small, the carbonaceous particles do not contact the surface of the CaO particles and each exists independently. However, if the CaO particles are too large, the reaction interface area becomes small, so the average particle size of the CaO particles is preferably 300 μm or less.
また、炭素質粒子の配合率を変化させて試験を行ったところ、図3に示すように、CaO系脱硫剤における配合率が1質量%以上のときに脱硫反応促進効果が得られた。これは、1質量%未満の配合率ではCaO系脱硫剤が溶鉄に巻き込まれる前に配合した炭素質粒子が大気中の酸素と反応し、結果的に炭素質粒子による濡れ性の改善効果が減少してしまうからである。炭素質粒子の配合率の上限は特に規定する必要はないが、余り多すぎると、CaO粒子と溶鉄とが接触しなくなるので、配合率は5質量%以下とすることが望ましい。   Moreover, when the test was performed by changing the blending ratio of the carbonaceous particles, as shown in FIG. 3, a desulfurization reaction promoting effect was obtained when the blending ratio in the CaO-based desulfurizing agent was 1% by mass or more. This is because when the blending ratio is less than 1% by mass, the carbonaceous particles blended before the CaO-based desulfurizing agent is involved in the molten iron reacts with oxygen in the atmosphere, resulting in a decrease in wettability improvement effect by the carbonaceous particles. Because it will do. The upper limit of the mixing ratio of the carbonaceous particles is not particularly required, but if it is too much, the CaO particles and the molten iron are not brought into contact with each other, so the mixing ratio is desirably 5% by mass or less.
また、本発明に係るCaO系脱硫剤においては、主成分であるCaOと反応して低融点化合物を形成する物質を滓化促進剤として配合しても構わない。具体的には、Al23 やSiO2 を主成分とする物質を適量添加しても構わない。蛍石をはじめとするフッ素源(ハロゲン化物)も滓化促進剤として有効であるが、フッ素の環境への影響が問題視されており、また、本発明に係るCaO系脱硫剤では反応界面積が増大して脱硫反応が十分に促進されるので、フッ素源は添加しないことが好ましい。 Moreover, in the CaO type | system | group desulfurization agent which concerns on this invention, you may mix | blend the substance which reacts with CaO which is a main component and forms a low melting-point compound as a hatching accelerator. Specifically, an appropriate amount of a substance mainly composed of Al 2 O 3 or SiO 2 may be added. Fluorite sources such as fluorite (halides) are also effective as hatching accelerators, but the influence of fluorine on the environment is regarded as a problem, and the CaO-based desulfurization agent according to the present invention has a reaction interface area. Therefore, it is preferable not to add a fluorine source.
また更に、本発明に係るCaO系脱硫剤においては、脱酸のための金属物質を配合しても構わない。脱酸のための金属物質を添加すると、溶鉄の酸素ポテンシャルが低減し、脱硫反応が促進されるからである。脱酸のための金属物質としては、Al、Si、Mgなどの鉄よりも酸素との親和力の強い元素を金属状態で含有している物質や合金などを用いればよい。   Furthermore, in the CaO-based desulfurizing agent according to the present invention, a metal substance for deoxidation may be blended. This is because the addition of a metal substance for deoxidation reduces the oxygen potential of the molten iron and promotes the desulfurization reaction. As a metal substance for deoxidation, a substance or an alloy containing an element having an affinity for oxygen stronger than that of iron such as Al, Si, or Mg may be used.
本発明に係るCaO系脱硫剤はCaO粉体と炭素質粒子とを所定量配合し、粘結剤などを添加することなくこれらを機械的に混合するだけで製造できるので、比較的低コストで製造可能である。尚、使用する炭素質粒子としては、カーボンブラック、コークス、石炭、木炭、黒鉛などの粒子であり、これらの材料は工業的に製造された製品だけではなく、これら製品の製造工程で発生する副生品やダスト、及び廃棄物も使用することができる。但し、使用する際には前述の通り、平均粒径を5μm以下好ましくは1μm以下にしなければならない。   The CaO-based desulfurization agent according to the present invention can be manufactured by mixing a predetermined amount of CaO powder and carbonaceous particles and mechanically mixing them without adding a binder, etc. It can be manufactured. The carbonaceous particles used are particles such as carbon black, coke, coal, charcoal, and graphite. These materials are not only industrially manufactured products but also secondary products generated in the manufacturing process of these products. Raw products, dust, and waste can also be used. However, when used, the average particle diameter must be 5 μm or less, preferably 1 μm or less, as described above.
本発明に係るCaO系脱硫剤は、溶銑鍋などに収容された溶銑或いは取鍋などに収容された溶鋼に、脱硫処理を施すプロセスに適用することができる。つまり、溶銑にもまた溶鋼にも適用することができる。その際に、CaO系脱硫剤の添加方法としては、攪拌羽根により攪拌されている溶鉄の浴面に上置き添加する方法、上吹きランスを介して搬送用ガスとともに攪拌羽根などにより攪拌されている溶鉄の浴面に向けて吹き付けて添加する方法、溶鉄中に浸漬させた浸漬ランスを介して搬送用ガスとともに溶銑中に吹き込んで添加する方法などを採用することができる。特に、溶銑の脱硫処理に適用する際には、攪拌力が強く、高い脱硫効率が得られることから、溶銑中に浸漬させた攪拌羽根により攪拌する機械攪拌式脱硫装置を用いた脱硫処理に適用することが好ましい。尚、脱硫反応は還元反応であるので、使用する搬送用ガスとしては、窒素ガスやArガスなどの不活性ガス、または、プロパンガスなどの還元性ガスなどを用いることが好ましい。   The CaO-based desulfurizing agent according to the present invention can be applied to a process of performing a desulfurization treatment on molten steel accommodated in a hot metal ladle or the like, or molten steel accommodated in a ladle or the like. That is, the present invention can be applied to both hot metal and molten steel. At that time, as a method of adding the CaO-based desulfurizing agent, a method of adding the CaO-based desulfurization agent over the bath surface of the molten iron being stirred by the stirring blade, stirring by the stirring blade or the like with the carrier gas through the upper blowing lance. A method of adding the molten iron by spraying it toward the bath surface, a method of adding it by blowing it into the molten iron together with a carrier gas through an immersion lance immersed in the molten iron, and the like can be employed. In particular, when applied to hot metal desulfurization treatment, since the stirring power is strong and high desulfurization efficiency is obtained, it is applied to desulfurization treatment using a mechanical stirring desulfurization device that stirs with a stirring blade immersed in hot metal. It is preferable to do. Since the desulfurization reaction is a reduction reaction, it is preferable to use an inert gas such as nitrogen gas or Ar gas or a reducing gas such as propane gas as the carrier gas to be used.
本発明によれば、CaO粒子表面に付着した炭素質粒子により、CaO系脱硫剤と溶鉄との濡れ性が向上し、添加したCaO粒子の凝集が抑制されてCaO粒子を細かいままの状態で溶鉄中に侵入且つ分散させることができるので、脱硫反応界面積が増加して効率的に脱硫処理することができる。そして、付着させる炭素質粒子の平均粒径が5μm以下、好ましくは1μm以下であるので、粘結剤などを使用しなくてもCaO粒子と混合するだけでCaO粒子の表面に付着させることができ、製造方法が簡単であり製造コストを抑えることができる。   According to the present invention, the carbonaceous particles adhering to the surface of the CaO particles improve the wettability between the CaO-based desulfurizing agent and the molten iron, the aggregation of the added CaO particles is suppressed, and the molten iron remains in a fine state. Since it can penetrate | invade and disperse | distribute in it, desulfurization reaction interfacial area increases and it can desulfurize efficiently. And since the average particle diameter of the carbonaceous particles to be adhered is 5 μm or less, preferably 1 μm or less, it can be adhered to the surface of the CaO particles only by mixing with the CaO particles without using a binder or the like. The manufacturing method is simple and the manufacturing cost can be reduced.
図4に示す機械攪拌式脱硫装置において、炭素質粒子のサイズ、炭素質粒子の配合率、CaO粒子のサイズを変化させて作製したCaO系脱流剤を用いた溶銑の脱硫処理試験を実施した。図4において、1は台車、2は溶銑鍋、3は溶銑、4は攪拌羽根、5は投入シュート、6はCaO系脱硫剤であり、台車1に積載された溶銑鍋2に収容された約300トンの溶銑3に攪拌羽根4を浸漬させ、軸4aを回転させて溶銑3を攪拌しながら、CaO系脱硫剤6を、投入シュート5を介して溶銑浴面に一括上置き添加し、攪拌羽根4による攪拌を所定時間実施し、溶銑3に脱硫処理を施した。炭素質粒子としてはカーボンブラックを使用し、CaO系脱硫剤6の添加量は5.0kg/tの一定値とした。溶銑成分、攪拌羽根回転数、脱硫処理時間などの処理条件を表1に示す。   In the mechanical stirring type desulfurization apparatus shown in FIG. 4, a hot metal desulfurization treatment test using a CaO-based desulfurizing agent produced by changing the size of carbonaceous particles, the mixing ratio of carbonaceous particles, and the size of CaO particles was performed. . In FIG. 4, 1 is a cart, 2 is a hot metal ladle, 3 is hot metal, 4 is a stirring blade, 5 is a charging chute, 6 is a CaO-based desulfurizing agent, and is accommodated in a hot metal ladle 2 loaded on the cart 1. The stirrer blade 4 is immersed in 300 tons of hot metal 3 and the shaft 4a is rotated to stir the hot metal 3 while adding the CaO-based desulfurizing agent 6 to the hot metal bath surface via the charging chute 5 and stirring. Agitation by the blades 4 was performed for a predetermined time, and the hot metal 3 was subjected to desulfurization treatment. Carbon black was used as the carbonaceous particles, and the amount of CaO-based desulfurizing agent 6 added was a constant value of 5.0 kg / t. Table 1 shows processing conditions such as hot metal components, stirring blade rotation speed, and desulfurization processing time.
CaO系脱硫剤6は、滓化促進剤であるCaF2 を3質量%配合したCaO−CaF2 −炭素質粒子系脱硫剤と、CaO−炭素質粒子系脱硫剤の2種類のCaO脱硫剤を使用し、それぞれのCaO系脱硫剤において、炭素質粒子の平均粒径、CaO粒子の平均粒径、炭素質粒子の配合率を変化させ、脱硫挙動を調査した。脱硫挙動は、脱硫処理前後に溶銑をサンプリングし、溶銑の硫黄濃度を分析して脱硫率で評価した。ここで、脱硫率は下記の(1)式で定義される値である。 The CaO-based desulfurization agent 6 includes two types of CaO desulfurization agents, a CaO-CaF 2 -carbonaceous particle-based desulfurization agent containing 3% by mass of CaF 2 as a hatching accelerator and a CaO-carbonaceous particle-based desulfurization agent. The desulfurization behavior was investigated by changing the average particle diameter of the carbonaceous particles, the average particle diameter of the CaO particles, and the blending ratio of the carbonaceous particles in each CaO-based desulfurization agent. The desulfurization behavior was evaluated by desulfurization rate by sampling hot metal before and after the desulfurization treatment and analyzing the sulfur concentration of the hot metal. Here, the desulfurization rate is a value defined by the following equation (1).
また、脱硫処理後、溶銑鍋内に形成されたスラグを回収し、スラグの平均粒径を調査した。更に、溶銑鍋内に形成されたスラグの質量計測値から脱硫剤の添加歩留りについても調査した。表2に、操業条件及び操業結果を示す。尚、表2の備考欄には、本発明の範囲内の試験には「本発明例」と表示し、それ以外の試験には「比較例」と表示している。   Moreover, after the desulfurization treatment, the slag formed in the hot metal ladle was collected, and the average particle size of the slag was investigated. Furthermore, the addition yield of the desulfurizing agent was also investigated from the measured mass value of the slag formed in the hot metal ladle. Table 2 shows the operation conditions and the operation results. In the remarks column of Table 2, “example of the present invention” is displayed for tests within the scope of the present invention, and “comparative example” is displayed for other tests.
試験No.1〜5は、CaO−CaF2 −炭素質粒子系脱硫剤において、炭素質粒子の平均粒径を0.1〜20μmの範囲で変化させ、炭素質粒子の粒径の影響を調査した操業であり、試験No.6〜10は、CaO−炭素質粒子系脱硫剤において、炭素質粒子の平均粒径を0.1〜20μmの範囲で変化させ、炭素質粒子の粒径の影響を調査した操業であり、試験No.11〜14は、CaO−炭素質粒子系脱硫剤において、炭素質粒子の配合率を1〜15質量%の範囲に変化させ、炭素質粒子の配合率の影響を調査した操業であり、試験No.15〜20は、CaO−炭素質粒子系脱硫剤において、炭素質粒子の平均粒径を1.0μm及び4.0μmの2水準とし、更にCaO粒子の平均粒径を7〜60μmの範囲で変化させ、炭素質粒子とCaO粒子との粒径比(炭素質粒子平均粒径/CaO粒子平均粒径)の影響を調査した操業である。 Test Nos. 1 to 5 were conducted by changing the average particle size of carbonaceous particles in the range of 0.1 to 20 μm in a CaO-CaF 2 -carbonaceous particle-based desulfurization agent, and investigating the influence of the particle size of the carbonaceous particles. Test Nos. 6 to 10 show that in the CaO-carbonaceous particle-based desulfurization agent, the average particle size of the carbonaceous particles was changed in the range of 0.1 to 20 μm, and the influence of the particle size of the carbonaceous particles was Test Nos. 11 to 14 show that in the CaO-carbonaceous particle-based desulfurization agent, the blending ratio of the carbonaceous particles is changed to a range of 1 to 15% by mass, and the blending ratio of the carbonaceous particles is The test No. 15 to 20 was conducted in CaO-carbonaceous particle-based desulfurization agent, and the average particle size of the carbonaceous particles was set to two levels of 1.0 μm and 4.0 μm. The average particle size is changed in the range of 7-60 μm, and carbonaceous particles and CaO particles A particle diameter ratio operation of the examination of the influence of (carbonaceous particles having an average particle diameter / CaO particles having an average particle diameter).
また、図5に、試験No.1〜10における脱硫率と炭素質粒子の平均粒径との関係を示し、図6に、試験No.11〜14における脱硫率と炭素質粒子の配合率との関係を示し、図7に、試験No.15〜20における脱硫率と粒径比(炭素質粒子平均粒径/CaO粒子平均粒径)との関係を示す。尚、図5〜7は表2のデータをグラフ化したものである。   5 shows the relationship between the desulfurization rate and the average particle size of the carbonaceous particles in Test Nos. 1 to 10, and FIG. 6 shows the desulfurization rate and the blending rate of the carbonaceous particles in Tests No. 11 to 14. 7 shows the relationship between the desulfurization rate and the particle size ratio (carbonaceous particle average particle size / CaO particle average particle size) in Test Nos. 15 to 20. 5 to 7 are graphs of the data in Table 2.
図5及び表2からも明らかなように、炭素質粒子の平均粒径が5μm以下になるとCaF2 を含有したCaO系脱硫剤であっても、また、CaF2を含有しないCaO系脱硫剤であっても、脱硫率が向上することが分かった。また、炭素質粒子の平均粒径が1μm以下になると、より一層脱硫率が向上することも分かった。尚、CaF2を含有したCaO系脱硫剤とCaF2 を含有しないCaO系脱硫剤とで脱硫率の絶対値に差が見られるが、この差は、CaF2によるCaOの滓化促進効果に基づくものである。しかし、平均粒径が1μm以下の炭素質粒子を混合したCaO−炭素質粒子系脱硫剤では、平均粒径が5μmを超える炭素質粒子を混合したCaO−CaF2−炭素質粒子系脱硫剤と同等の脱硫率になることが分かった。つまり、本発明に係るCaO系脱硫剤においては、CaF2 を添加しなくても、従来のCaF2を添加したCaO系脱硫剤と同等以上の脱硫率が得られることが分かった。 5 and as is apparent from Table 2, even in CaO-based desulfurizing agent average particle size of the carbonaceous particles contained CaF 2 becomes to 5μm or less, and in CaO-based desulfurizing agent containing no CaF 2 Even if it exists, it turned out that a desulfurization rate improves. It was also found that the desulfurization rate was further improved when the average particle size of the carbonaceous particles was 1 μm or less. Although a difference in the absolute value of the desulfurization rate and the CaO-based desulfurizing agent containing no CaO-based desulfurizing agent and CaF 2 which contains CaF 2 is seen, this difference is based on the slag formation promoting effect of CaO by CaF 2 Is. However, in a CaO-carbonaceous particle-based desulfurization agent in which carbonaceous particles having an average particle diameter of 1 μm or less are mixed, a CaO-CaF 2 -carbonaceous particle-based desulfurization agent in which carbonaceous particles having an average particle diameter exceeding 5 μm are mixed with It was found that the desulfurization rate was equivalent. That is, in the CaO-based desulfurizing agent according to the present invention, even without the addition of CaF 2, it was found that the addition of conventional CaF 2 was CaO-based desulfurizing agent equal to or higher than the desulfurization rate is obtained.
また、図6及び表2からも明らかなように、炭素質粒子の配合率が1質量%以上であれば、60%以上の脱硫率が得られることが分かった。但し、炭素質粒子の配合率がおよそ5質量%程度で脱硫率が最大値となることから、5質量%を超える配合は必要ではないことが分かった。   Further, as is apparent from FIG. 6 and Table 2, it was found that a desulfurization rate of 60% or more can be obtained when the mixing ratio of the carbonaceous particles is 1% by mass or more. However, since the desulfurization rate becomes the maximum when the blending ratio of the carbonaceous particles is about 5% by mass, it was found that the blending exceeding 5% by mass is not necessary.
また、図7及び表2からも明らかなように、粒径比(炭素質粒子平均粒径/CaO粒子平均粒径)が小さくなるほど脱硫率は向上することが分かった。具体的には、粒径比(炭素質粒子平均粒径/CaO粒子平均粒径)が0.07以下になると脱硫率が向上することから、炭素質粒子の平均粒径を5μm以下とするとともに、CaO粒子の平均粒径に応じて、粒径比(炭素質粒子平均粒径/CaO粒子平均粒径)が0.07以下となるように、炭素質粒子の平均粒径を調整することが好ましい。   Further, as apparent from FIG. 7 and Table 2, it was found that the desulfurization rate was improved as the particle size ratio (average particle size of carbonaceous particles / average particle size of CaO particles) was decreased. Specifically, when the particle size ratio (carbonaceous particle average particle size / CaO particle average particle size) is 0.07 or less, the desulfurization rate is improved, so that the average particle size of the carbonaceous particles is 5 μm or less. Depending on the average particle diameter of the CaO particles, the average particle diameter of the carbonaceous particles may be adjusted so that the particle diameter ratio (carbonaceous particle average particle diameter / CaO particle average particle diameter) is 0.07 or less. preferable.
また更に、表2からも明らかなように、処理後スラグの平均粒径が小さいCaO系脱硫剤ほど脱硫率は高くなり、また、添加歩留りの高い脱硫剤ほど脱硫率は高くなることが確認できた。   Further, as is clear from Table 2, it can be confirmed that the CaO-based desulfurization agent having a smaller average particle diameter of the treated slag has a higher desulfurization rate, and the desulfurization agent having a higher addition yield has a higher desulfurization rate. It was.
機械攪拌式脱硫装置を模擬した実験装置の概略図である。It is the schematic of the experimental apparatus which simulated the mechanical stirring desulfurization apparatus. 実験装置での脱硫処理における溶銑中硫黄濃度の推移を脱硫剤の種類別に比較して示す図である。It is a figure which shows the transition of the sulfur concentration in hot metal in the desulfurization process by an experimental apparatus, according to the kind of desulfurization agent. 炭素質粒子の配合率と脱硫反応速度定数との関係を示す図である。It is a figure which shows the relationship between the compounding rate of a carbonaceous particle, and a desulfurization reaction rate constant. 実施例において使用した機械攪拌式脱硫装置の概略図である。It is the schematic of the mechanical stirring desulfurization apparatus used in the Example. 試験No.1〜10における脱硫率と炭素質粒子の平均粒径との関係を示す図である。It is a figure which shows the relationship between the desulfurization rate in test No.1-10, and the average particle diameter of a carbonaceous particle. 試験No.11〜14における脱硫率と炭素質粒子の配合率との関係を示す図である。It is a figure which shows the relationship between the desulfurization rate in Test No.11-14, and the compounding rate of a carbonaceous particle. 試験No.15〜20における脱硫率と炭素質粒子径/CaO粒子径との関係を示す図である。It is a figure which shows the relationship between the desulfurization rate in test No.15-20, and a carbonaceous particle diameter / CaO particle diameter.
符号の説明Explanation of symbols
1 台車
2 溶銑鍋
3 溶銑
4 攪拌羽根
5 投入シュート
6 CaO系脱硫剤
7 実験装置
8 電動機
9 坩堝容器
10 高周波加熱コイル
DESCRIPTION OF SYMBOLS 1 Bogie 2 Hot metal ladle 3 Hot metal 4 Stirrer blade 5 Input chute 6 CaO type desulfurization agent 7 Experimental device 8 Electric motor 9 Crucible container 10 High frequency heating coil

Claims (11)

  1. 主成分がCaO粒子であるCaO系脱硫剤において、前記CaO粒子の平均粒径は10μm以上であり、平均粒径が5μm以下である、主成分を炭素とする炭素質粒子を、前記CaO粒子と混合させたものであることを特徴とするCaO系脱硫剤。 In the CaO-based desulfurization agent in which the main component is CaO particles, the CaO particles have an average particle size of 10 μm or more and an average particle size of 5 μm or less. A CaO-based desulfurization agent characterized by being mixed.
  2. 前記炭素質粒子の平均粒径は1μm以下であることを特徴とする、請求項1に記載のCaO系脱硫剤。   The CaO-based desulfurization agent according to claim 1, wherein an average particle size of the carbonaceous particles is 1 μm or less.
  3. 前記CaO系脱硫剤における前記炭素質粒子の配合率は1質量%以上であることを特徴とする、請求項1または請求項2に記載のCaO系脱硫剤。 The CaO-based desulfurizing agent according to claim 1 or 2 , wherein a blending ratio of the carbonaceous particles in the CaO-based desulfurizing agent is 1% by mass or more.
  4. 前記CaO系脱硫剤は、CaOと反応して低融点化合物を形成する物質を含有することを特徴とする、請求項1ないし請求項の何れか1つに記載のCaO系脱硫剤。 The CaO-based desulfurizing agent according to any one of claims 1 to 3 , wherein the CaO-based desulfurizing agent contains a substance that reacts with CaO to form a low melting point compound.
  5. 前記CaO系脱硫剤は、フッ素を含有しないことを特徴とする、請求項1ないし請求項の何れか1つに記載のCaO系脱硫剤。 The CaO-based desulfurization agent according to any one of claims 1 to 4 , wherein the CaO-based desulfurization agent does not contain fluorine.
  6. 前記CaO系脱硫剤は、脱酸のための金属物質を含有することを特徴とする、請求項1ないし請求項の何れか1つに記載のCaO系脱硫剤。 The CaO-based desulfurization agent according to any one of claims 1 to 5 , wherein the CaO-based desulfurization agent contains a metal substance for deoxidation.
  7. 処理容器内に収容された溶鉄に、請求項1ないし請求項の何れか1つに記載された脱硫剤を添加して脱硫処理することを特徴とする、溶鉄の脱硫処理方法。 A desulfurization treatment method for molten iron, wherein the desulfurization agent according to any one of claims 1 to 6 is added to the molten iron accommodated in the treatment vessel to perform desulfurization treatment.
  8. 前記脱硫剤を、溶鉄の浴面上方から上置き添加することを特徴とする、請求項に記載の溶鉄の脱硫処理方法。 The method for desulfurizing molten iron according to claim 7 , wherein the desulfurizing agent is added on top of the molten iron bath surface.
  9. 前記脱硫剤を、上吹きランスを介して搬送用ガスとともに溶鉄浴面に吹き付けて添加することを特徴とする、請求項に記載の溶鉄の脱硫処理方法。 The method for desulfurizing molten iron according to claim 7 , wherein the desulfurizing agent is added by spraying on the molten iron bath surface together with a carrier gas through an upper blowing lance.
  10. 前記脱硫剤を、浸漬ランスを介して搬送ガスとともに溶鉄浴中に吹き込んで添加することを特徴とする、請求項に記載の溶鉄の脱硫処理方法。 The method for desulfurizing molten iron according to claim 7 , wherein the desulfurizing agent is added by being blown into a molten iron bath together with a carrier gas through an immersion lance.
  11. 前記処理容器に収容された溶鉄を、攪拌羽根によって攪拌しながら脱硫処理することを特徴とする、請求項ないし請求項10の何れか1つに記載の溶鉄の脱硫処理方法。 The molten iron contained in the processing container, characterized in that the desulfurization treatment with stirring by stirring blades, desulfurization treatment method of molten iron according to any one of claims 7 to 10.
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