JP5026747B2 - Method for producing CaO-based desulfurization agent - Google Patents

Method for producing CaO-based desulfurization agent Download PDF

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JP5026747B2
JP5026747B2 JP2006208043A JP2006208043A JP5026747B2 JP 5026747 B2 JP5026747 B2 JP 5026747B2 JP 2006208043 A JP2006208043 A JP 2006208043A JP 2006208043 A JP2006208043 A JP 2006208043A JP 5026747 B2 JP5026747 B2 JP 5026747B2
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desulfurization
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desulfurization agent
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友紀 草間
信孝 中山
山口  篤
雄太 日野
由枝 中井
郁宏 鷲見
誠司 鍋島
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Jfeミネラル株式会社
Jfeスチール株式会社
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Description

本発明は、溶鉄の脱硫処理に使用するCaO系脱硫剤の製造方法に関するものである。   The present invention relates to a method for producing a CaO-based desulfurization agent used for the desulfurization treatment of molten iron.
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では、付着の概念が曖昧であり、CaO粒子にどの程度までSiC粒子または黒鉛粒子を付着させる必要があるか記載されていない。つまり、溶鉄との濡れ性を向上させたCaO系脱硫剤を安定して製造できない恐れがあるという問題がある。   However, in patent document 1, the concept of adhesion is ambiguous and does not describe how much SiC particles or graphite particles need to be adhered to CaO particles. That is, there exists a problem that there exists a possibility that the CaO type | system | group desulfurization agent which improved the wettability with molten iron may not be manufactured stably.
また、特許文献1では、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く、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いる。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粒子及び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。   Moreover, in patent document 1, in order to suppress manufacturing cost, 5-10 micrometers is mentioned as a preferable average particle diameter of SiC particle | grains and graphite particle | grains, SiC particle | grains and graphite particle | grains of this average particle diameter have an adhesion layer on the surface. The particles to be formed have a particle size that is too large and hardly adheres to the surface of the CaO particles. Therefore, in Patent Document 1, a resin-based organic solvent is used as a binder. Since it is forcibly attached using a binder, about 12% by mass of SiC particles and graphite particles are required (see paragraph [0021]), and as a result, a large amount of SiC particles or graphite particles are required. There is a problem that the production cost of the desulfurizing agent is increased, for example, the need for the binder and the necessity of adding the binder make the production process of the desulfurizing agent complicated.
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、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、簡便に且つ安価にしかも安定して製造することのできる製造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 enables highly efficient desulfurization treatment, easily and inexpensively. And it is providing the manufacturing method which can be manufactured stably.
上記課題を解決するための第1の発明に係るCaO系脱硫剤の製造方法は、主成分をCaO粒子とし、該CaO粒子の表面に炭素質粒子が付着したCaO系脱硫剤の製造方法であって、平均粒径が10μm以上であるCaO粒子と、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とを混合してCaO粒子の表面に炭素質粒子を付着させることを特徴とするものである。 The method for producing a CaO-based desulfurizing agent according to the first invention for solving the above-mentioned problem is a method for producing a CaO-based desulfurizing agent in which the main component is CaO particles and carbonaceous particles are adhered to the surface of the CaO particles. Then, mixing CaO particles having an average particle diameter of 10 μm or more and carbonaceous particles having an average particle diameter of 5 μm or less and containing carbon as a main component to adhere the carbonaceous particles to the surface of the CaO particles. It is a feature.
第2の発明に係るCaO系脱硫剤の製造方法は、主成分を、平均粒径が10μm以上であるCaO粒子とし、該CaO粒子の表面に炭素質粒子が付着したCaO系脱硫剤の製造方法であって、塊状のCaOを粉砕して平均粒径が10μm以上であるCaO粒子とする際に、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添加し、塊状のCaOを粉砕すると同時に、粉砕して形成されるCaO粒子と炭素質粒子とを混合してCaO粒子の表面に炭素質粒子を付着させることを特徴とするものである。 The method for producing a CaO-based desulfurizing agent according to the second invention is a method for producing a CaO-based desulfurizing agent in which the main component is CaO particles having an average particle size of 10 μm or more , and carbonaceous particles are attached to the surface of the CaO particles. In addition, when crushing massive CaO to obtain CaO particles having an average particle diameter of 10 μm or more, carbonaceous particles having an average particle diameter of 5 μm or less and containing carbon as a main component are added, At the same time when CaO is pulverized, CaO particles and carbonaceous particles formed by pulverization are mixed to adhere the carbonaceous particles to the surface of the CaO particles.
第3の発明に係るCaO系脱硫剤の製造方法は、第1または第2の発明において、前記炭素質粒子の平均粒径が1μm以下であることを特徴とするものである。   A method for producing a CaO-based desulfurizing agent according to a third invention is characterized in that, in the first or second invention, the average particle diameter of the carbonaceous particles is 1 μm or less.
第4の発明に係るCaO系脱硫剤の製造方法は、第1ないし第3の発明の何れかにおいて、前記CaO粒子と前記炭素質粒子とを混合した後のCaO粒子の測色計による明度指数L* 値を30以下とすることを特徴とするものである。   According to a fourth aspect of the present invention, there is provided a method for producing a CaO-based desulfurization agent according to any one of the first to third aspects, wherein the CaO particles are mixed with the carbonaceous particles, and the lightness index of the CaO particles by a colorimeter is mixed. The L * value is 30 or less.
の発明に係るCaO系脱硫剤の製造方法は、第1ないし第の発明の何れかにおいて、前記CaO系脱硫剤における前記炭素質粒子の配合率が1質量%以上であることを特徴とするものである。 The method for producing a CaO-based desulfurizing agent according to a fifth invention is characterized in that, in any of the first to fourth inventions, the blending ratio of the carbonaceous particles in the CaO-based desulfurizing agent is 1% by mass or more. It is what.
の発明に係るCaO系脱硫剤の製造方法は、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。 The method for producing a CaO-based desulfurizing agent according to a sixth aspect of the invention is any one of the first to fifth aspects, wherein the CaO-based desulfurizing agent contains a substance that reacts with CaO to form a low melting point compound. It is characterized by.
の発明に係るCaO系脱硫剤の製造方法は、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。 According to a seventh aspect of the present invention, there is provided a method for producing a CaO-based desulfurizing agent according to any one of the first to sixth aspects, wherein the CaO-based desulfurizing agent does not contain fluorine.
の発明に係るCaO系脱硫剤の製造方法は、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。 The method for producing a CaO-based desulfurizing agent according to an eighth invention is characterized in that, in any of the first to seventh inventions, the CaO-based desulfurizing agent contains a metal substance for deoxidation. 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。また、CaO粒子と炭素質粒子とを混合した後のCaO粒子の測色計による明度指数L* 値を規定することにより、脱硫効率の高いCaO系脱硫剤を安定して製造することが可能となる。   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. In addition, it is possible to stably produce a CaO-based desulfurization agent having a high desulfurization efficiency by defining a lightness index L * value by a colorimeter of CaO particles after mixing CaO particles and carbonaceous particles. Become.
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。   Accordingly, 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 a contact angle much lower than that of CaO. Various investigations and studies were conducted on improving wettability by using a relatively simple method.
その結果、炭素質粒子が微粒子であれば特別な粘結剤を使用しなくても、CaO粒子と炭素質粒子とを混合するだけでCaO粒子の表面に炭素質粒子を付着させることができ、高い脱硫性能が得られることが分かった。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。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。   As a result, if the carbonaceous particles are fine particles, the carbonaceous particles can be attached to the surface of the CaO particles simply by mixing the CaO particles and the carbonaceous particles without using a special binder. It was found that high desulfurization performance can be obtained. 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. These materials can be used not only for industrially manufactured products, but also by-products, dusts, and waste generated in the manufacturing process of these products.
即ち、平均粒径が5μm以下の炭素質粒子をCaO粒子と混合するだけで、特別な粘結剤を添加しなくても、表面を炭素質粒子で被覆されたCaO粒子を製造できることが分かった。この場合、CaO粒子の表面を炭素質粒子で被覆するには、炭素質粒子の粒径がCaO粒子の粒径に比べて小さい方が望ましく、この観点から炭素質粒子の平均粒径は1μm以下であることが好ましい。炭素質粒子の平均粒径が5μmを超えるとCaO粒子との粒径差が小さくなり、CaO粒子の表面を炭素質粒子で均一に覆うことができなくなる。   That is, it was found that by simply mixing carbonaceous particles having an average particle size of 5 μm or less with CaO particles, CaO particles whose surfaces are coated with carbonaceous particles can be produced without adding a special binder. . In this case, in order to coat the surface of the CaO particles with the carbonaceous particles, it is desirable that the carbonaceous particles have a smaller particle size than the CaO particles. From this viewpoint, the average particle size of the carbonaceous particles is 1 μm or less. It is preferable that If the average particle size of the carbonaceous particles exceeds 5 μm, the particle size difference from the CaO particles becomes small, and the surface of the CaO particles cannot be uniformly covered with the carbonaceous particles.
以下に、CaO系脱硫剤の製造方法を更に詳しく説明する。   Below, the manufacturing method of a CaO type | system | group desulfurization agent is demonstrated in more detail.
表面に炭素質粒子が被覆されたCaO系脱硫剤を製造するに当たり、CaO粒子の表面に炭素質粒子を被覆させるためには、主成分であるCaO粒子と、平均粒径が5μm以下好ましくは1μm以下の炭素質粒子とを均一に混合する必要があり、単にそれぞれの原材料を添加するだけでは、脱硫効率の向上は期待できない。混合時には、これらの原材料以外に、CaOと反応して低融点化合物を形成する物質や、溶鉄の脱酸を目的とした金属物質を添加し混合しても構わない。   In producing a CaO-based desulfurization agent having a surface coated with carbonaceous particles, in order to coat the surface of CaO particles with carbonaceous particles, CaO particles as a main component and an average particle size of 5 μm or less, preferably 1 μm It is necessary to uniformly mix the following carbonaceous particles, and simply adding the respective raw materials cannot be expected to improve desulfurization efficiency. At the time of mixing, in addition to these raw materials, a substance that reacts with CaO to form a low melting point compound or a metal substance for the purpose of deoxidizing molten iron may be added and mixed.
その際に使用する混合装置は、炭素質粒子が均一に分散される装置である限りどのような装置であっても構わず、特に限定する必要はないが、微粒の炭素質粒子からなる凝集体を開砕・分散させながら混合する、例えば高速回転型のミキサーのような強い対流混合、拡散混合、剪断混合を同時に行わせることのできる混合装置を用いることが好ましい。   The mixing device used at that time may be any device as long as it is a device in which carbonaceous particles are uniformly dispersed, and there is no particular limitation, but an aggregate composed of fine carbonaceous particles. It is preferable to use a mixing apparatus capable of simultaneously carrying out strong convection mixing, diffusion mixing, and shear mixing, such as a high-speed rotating mixer.
CaO粒子と炭素質粒子との混合度合の指標は、測色計による明度測定により評価することができる。測色計は、試料の色を測定し、JISなどで定められている方法で数字として表すことのできる装置であり、明度は、例えばJIS Z 8729で定義されたL* a* b* 表色系の明度指数L* 値で表すことができ、明度指数L* 値の数値が低いほど黒色であることを示している。   The index of the degree of mixing of CaO particles and carbonaceous particles can be evaluated by measuring the brightness with a colorimeter. The colorimeter is a device that can measure the color of a sample and express it as a number by a method defined by JIS, etc., and the brightness is, for example, the L * a * b * color specification defined by JIS Z 8729 The lightness index L * value of the system can be represented, and the lower the value of the lightness index L * value, the more black it is.
炭素質粒子は黒色であることから、炭素質粒子がCaO粒子を均一に覆うほど、更には、炭素質粒子がCaO粒子を厚く覆うほど、CaO粒子は黒味を帯びるので、明度はより低い値を示すようになる。本発明者等は、炭素質粒子によるCaO粒子の被覆が十分に行われ、脱硫反応が促進されるのは、炭素質粒子とCaO粒子とを混合した後のCaO粒子の測色計により測定される明度指数L* 値が30以下の場合であることを確認している。つまり、CaO粒子の測色計により測定される明度指数L* 値が30以下となるまで、混合することが好ましい。特に、明度指数L* 値が20以下になるまで混合すると、脱硫反応がより一層促進されることを確認している。一方、明度指数L* 値が30を超えると、炭素質粒子によるCaO粒子の被覆は不十分であり、脱硫反応の効率向上は少ない。   Since the carbonaceous particles are black, the more the carbonaceous particles cover the CaO particles, and the thicker the carbonaceous particles cover the CaO particles, the darker the CaO particles, and the lower the lightness value. Will come to show. The inventors of the present invention have sufficiently measured that the CaO particles are sufficiently covered with the carbonaceous particles, and the desulfurization reaction is promoted by a colorimeter of the CaO particles after mixing the carbonaceous particles and the CaO particles. The lightness index L * value is confirmed to be 30 or less. That is, it is preferable to mix until the lightness index L * value measured by the colorimeter of CaO particles is 30 or less. In particular, it has been confirmed that the desulfurization reaction is further promoted by mixing until the lightness index L * value is 20 or less. On the other hand, when the lightness index L * value exceeds 30, the coating of the CaO particles with the carbonaceous particles is insufficient, and the efficiency improvement of the desulfurization reaction is small.
また、このCaO系脱硫剤を製造するに当たり、主成分であるCaO粒子を得るための粉砕工程と、CaO粒子と炭素質粒子との混合工程とを同時に行うこともできる。CaO粒子は、粒径が10〜50mm程度の塊状のCaOを粉砕処理して作製するが、この粉砕工程に炭素質粒子を添加して、CaOの粉砕処理と、CaO粒子と炭素質粒子との混合処理とを同時に実施してもよい。炭素質粒子とCaO粒子との混合度合は、上記と同様に明度指数L* 値によって判定すればよい。   Moreover, when manufacturing this CaO type | system | group desulfurization agent, the grinding | pulverization process for obtaining CaO particle | grains which are main components, and the mixing process of CaO particle | grains and carbonaceous particle | grains can also be performed simultaneously. The CaO particles are produced by pulverizing massive CaO having a particle size of about 10 to 50 mm, and adding carbonaceous particles to the pulverization step to form the CaO pulverization treatment and the CaO particles and the carbonaceous particles. You may implement a mixing process simultaneously. The mixing degree of the carbonaceous particles and the CaO particles may be determined by the brightness index L * value as described above.
ここで、CaO系脱硫剤を構成するCaO粒子の粒径は、平均粒径で10μm以上であることが好ましい。CaO粒子の粒子径が小さくなり過ぎると、CaO粒子と炭素質粒子との粒径差が小さくなり、炭素質粒子の被覆が十分でなくなり、脱硫効率が向上しない。一方、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。   Here, it is preferable that the particle diameter of the CaO particle | grains which comprise a CaO type | system | group desulfurization agent is 10 micrometers or more by an average particle diameter. If the particle diameter of the CaO particles becomes too small, the difference in particle size between the CaO particles and the carbonaceous particles becomes small, and the coating of the carbonaceous particles becomes insufficient, and the desulfurization efficiency is not improved. On the other hand, if the CaO particles are made 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CaO系脱硫剤における配合率は、1質量%以上とすることが好ましい。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恐れがあるからである。また、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、余り多くしても、CaO粒子の表面に炭素質粒子が満遍なく付着している限り、CaO粒子と溶鉄との濡れ性の改善効果は飽和し、それ以上の炭素質粒子の配合は無駄になるので、配合率の上限は5質量%程度とすることが望ましい。また、炭素質粒子が多すぎると、CaO粒子と溶鉄とが接触しなくなり、脱硫反応が阻害されるという問題も発生する。   Moreover, it is preferable that the compounding rate in the CaO type | system | group desulfurization agent of a carbonaceous particle shall be 1 mass% or more. When the blending ratio is less than 1% by mass, the blended carbonaceous particles react with oxygen in the atmosphere before the CaO-based desulfurizing agent is involved in the molten iron, resulting in a reduction in wettability improvement effect by the carbonaceous particles. This is because there is a risk of it. In addition, the upper limit of the mixing ratio of the carbonaceous particles does not need to be specified, but even if the amount is too large, as long as the carbonaceous particles are evenly adhered to the surface of the CaO particles, the wettability between the CaO particles and the molten iron is not limited. Since the improvement effect is saturated and the blending of more carbonaceous particles is useless, the upper limit of the blending ratio is desirably about 5% by mass. Moreover, when there are too many carbonaceous particles, the CaO particle | grains and molten iron will not contact, and the problem that desulfurization reaction will be generated also generate | occur | produces.
また更に、脱硫反応を促進させるために、CaO系脱硫剤の製造時に、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、本発明により製造される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。また、脱硫反応を促進させるために、CaO系脱硫剤の製造時に、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 order to accelerate the desulfurization reaction, a substance that reacts with CaO as a main component to form a low melting point compound may be added as a hatching accelerator during the production of the CaO-based desulfurization agent. Specifically, an appropriate amount of a substance mainly composed of Al 2 O 3 or SiO 2 may be added. Fluorite and other fluorine sources (halides) are also effective as hatching accelerators, but the influence of fluorine on the environment is regarded as a problem, and the CaO-based desulfurizing agent produced according to the present invention is reactive. Since the interfacial area increases and the desulfurization reaction is sufficiently promoted, it is preferable not to add a fluorine source. Further, in order to promote the desulfurization reaction, a metal substance for deoxidation may be blended during the production of the CaO-based desulfurization agent. 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.
本発明では、このようにして炭素質粒子により被覆されたCaO粒子を主成分とするCaO系脱硫剤を製造する。本発明により製造された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。   In this invention, the CaO type | system | group desulfurization agent which has as a main component CaO particle | grains coat | covered with the carbonaceous particle in this way is manufactured. The CaO-based desulfurizing agent produced according to the present invention can be applied to a process of performing a desulfurization process on molten steel accommodated in a hot metal ladle or a ladle. That is, the present invention can be applied to both hot metal and molten steel.
以上説明したように、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。   As described above, 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, only mixing with CaO particles without using a binder or the like. Carbonaceous particles can be attached to the surface of the CaO particles. 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.
本発明方法に基づいて製造したCaO系脱硫剤(本発明例1〜7)と、本発明方法以外の方法で製造したCaO系脱硫剤(比較例1〜3)とを準備し、これらのCaO系脱硫剤を用いて溶銑の脱硫処理を実施した。   A CaO-based desulfurizing agent (Invention Examples 1 to 7) manufactured based on the method of the present invention and a CaO-based desulfurizing agent (Comparative Examples 1 to 3) manufactured by a method other than the method of the present invention were prepared. A hot metal desulfurization treatment was carried out using a system desulfurization agent.
本発明例1〜6では、CaO粒子と炭素質粒子とを予め準備し、これらを混合してCaO系脱硫剤を製造した。その際に、CaO系脱硫剤の基本構成として、炭素質粒子としては平均粒径が1μmのカーボンブラックを使用し、CaO粒子は平均粒径が40μmのものを使用した。但し、本発明例1では、平均粒径が10μmのCaO粒子を使用し、また、本発明例6では平均粒径が0.1μmのカーボンブラックを使用し、脱硫率に及ぼすこれら粒径の影響を調査した。また、本発明例3では滓化促進剤としてのAl23 粉を混合し、本発明例4では滓化促進剤としての蛍石粉を混合し、本発明例5では脱酸剤としての金属Al粉を混合した。混合後のCaO粒子の測色計により測定される明度指数L* 値は、本発明例1では25、本発明例2〜5では30、本発明例6では20であった。 In Invention Examples 1 to 6, CaO particles and carbonaceous particles were prepared in advance, and these were mixed to produce a CaO-based desulfurization agent. At that time, as a basic configuration of the CaO-based desulfurizing agent, carbon black having an average particle diameter of 1 μm was used as the carbonaceous particles, and CaO particles having an average particle diameter of 40 μm were used. However, in Example 1 of the present invention, CaO particles having an average particle diameter of 10 μm were used, and in Example 6 of the present invention, carbon black having an average particle diameter of 0.1 μm was used, and the influence of these particle diameters on the desulfurization rate. investigated. In Invention Example 3, Al 2 O 3 powder as a hatching accelerator was mixed, in Invention Example 4, fluorite powder as a hatching accelerator was mixed, and in Invention Example 5, a metal as a deoxidizer. Al powder was mixed. The lightness index L * value measured by the colorimeter of the CaO particles after mixing was 25 in Invention Example 1, 30 in Invention Examples 2 to 5, and 20 in Invention Example 6.
また、本発明例7では、塊状のCaOの粉砕工程に平均粒径が0.1μmのカーボンブラックを混合し、CaOの粉砕工程と、生成されるCaO粒子とカーボンブラックとの混合工程とを同時に実施した。この場合、混合後のCaO粒子の測色計により測定される明度指数L* 値は20であった。   Further, in Example 7 of the present invention, carbon black having an average particle size of 0.1 μm is mixed in the pulverized CaO pulverization step, and the CaO pulverization step and the generated CaO particle and carbon black mixing step are simultaneously performed. Carried out. In this case, the lightness index L * value measured by the colorimeter of the CaO particles after mixing was 20.
一方、比較例1はCaO粒子のみを混合したCaO系脱硫剤、比較例2は炭素質粒子の平均粒径が本発明の範囲を外れたCaO系脱硫剤、比較例3はCaO粒子とカーボンブラックとを混合せず、CaO粒子にカーボンブラックを添加しただけのCaO系脱硫剤である。   On the other hand, Comparative Example 1 is a CaO-based desulfurizing agent in which only CaO particles are mixed, Comparative Example 2 is a CaO-based desulfurizing agent in which the average particle size of carbonaceous particles is outside the scope of the present invention, and Comparative Example 3 is CaO particles and carbon black. And a CaO-based desulfurization agent in which carbon black is added to CaO particles.
脱硫処理条件は、機械攪拌式脱硫装置を用い、処理前の溶銑温度を1300℃に調整し、処理時間を20分、脱硫剤の原単位を5kg/tとし、攪拌羽根により溶銑を攪拌して行った。表1に、各CaO系脱硫剤の組成、製造方法及び脱硫率を示す。   The desulfurization treatment conditions were as follows. Using a mechanical stirring desulfurization apparatus, the hot metal temperature before treatment was adjusted to 1300 ° C, the treatment time was 20 minutes, the basic unit of the desulfurizing agent was 5 kg / t, and the hot metal was stirred with a stirring blade. went. Table 1 shows the composition, production method, and desulfurization rate of each CaO-based desulfurization agent.
表1に示すように、本発明方法に基づき製造したCaO脱硫剤では、比較例の脱硫剤に比べて脱硫効率が向上することが確認できた。この中で、本発明例2をCaO脱硫剤の基本構成としての基準とすると、滓化促進剤を混合した本発明例3,4、及び脱酸剤を混合した本発明例5は、本発明例2に比べて脱硫率が向上した。特に、蛍石を混合した本発明例4は高い脱硫率を得ることができた。本発明例1は本発明例2と比較すると脱硫率が65%から70%へと若干向上した。このことは、本発明例1のL*値が本発明例2のL*値よりも低いことから、炭素質粒子がより十分に被覆しており、且つ、本発明例1のCaO粒子の平均粒径が本発明例2よりも小さいことから反応界面積が増加し、これらにより脱硫反応が促進したためである。   As shown in Table 1, it was confirmed that the CaO desulfurization agent produced based on the method of the present invention improved the desulfurization efficiency as compared with the desulfurization agent of the comparative example. Among them, when Example 2 of the present invention is used as a standard as a basic constitution of the CaO desulfurizing agent, Examples 3 and 4 of the present invention in which a hatching accelerator is mixed, and Example 5 of the present invention in which a deoxidizer is mixed Compared to Example 2, the desulfurization rate was improved. In particular, Invention Example 4 in which fluorite was mixed was able to obtain a high desulfurization rate. Inventive Example 1 slightly improved the desulfurization rate from 65% to 70% as compared with Inventive Example 2. This is because the L * value of Invention Example 1 is lower than the L * value of Invention Example 2, so that the carbonaceous particles are more fully coated, and the average of the CaO particles of Invention Example 1 is This is because the reaction interfacial area increased because the particle size was smaller than that of Invention Example 2, and the desulfurization reaction was promoted by these.
また、平均粒径が0.1μmのカーボンブラックを使用した本発明例6,7では、滓化促進剤或いは脱酸剤を混合しなくても高い脱硫率が得られることが確認できた。本発明例6と本発明例7とは製造方法に違いがあるが、脱硫率には差が見られず、製造方法の影響はないことが確認できた。つまり、予め粉砕したものを混合しても、CaOの粉砕と同時に炭素質粒子を混合しても、どちらの方法で製造しても構わないことが確認できた。   In addition, in Examples 6 and 7 of the present invention using carbon black having an average particle size of 0.1 μm, it was confirmed that a high desulfurization rate was obtained without mixing a hatching accelerator or a deoxidizer. Although the present invention example 6 and the present invention example 7 are different in the production method, no difference was observed in the desulfurization rate, and it was confirmed that there was no influence of the production method. In other words, it was confirmed that either a pre-ground material or a carbonaceous particle was mixed at the same time as the CaO pulverization could be used.

Claims (8)

  1. 主成分をCaO粒子とし、該CaO粒子の表面に炭素質粒子が付着したCaO系脱硫剤の製造方法であって、平均粒径が10μm以上であるCaO粒子と、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とを混合してCaO粒子の表面に炭素質粒子を付着させることを特徴とする、CaO系脱硫剤の製造方法。 A method for producing a CaO-based desulfurization agent in which a main component is CaO particles, and carbonaceous particles are adhered to the surface of the CaO particles, the CaO particles having an average particle size of 10 μm or more, and the average particle size of 5 μm or less. A method for producing a CaO-based desulfurization agent, comprising mixing carbonaceous particles containing carbon as a main component and adhering carbonaceous particles to the surface of CaO particles.
  2. 主成分を、平均粒径が10μm以上であるCaO粒子とし、該CaO粒子の表面に炭素質粒子が付着したCaO系脱硫剤の製造方法であって、塊状のCaOを粉砕して平均粒径が10μm以上であるCaO粒子とする際に、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添加し、塊状のCaOを粉砕すると同時に、粉砕して形成されるCaO粒子と炭素質粒子とを混合してCaO粒子の表面に炭素質粒子を付着させることを特徴とする、CaO系脱硫剤の製造方法。 The main component, and CaO particles having an average particle size of 10μm or more, a manufacturing method of the CaO-based desulfurizing agent carbonaceous particles adhered to the surface of the CaO particles, average particle size by grinding CaO massive When the CaO particles having a mean particle diameter of 5 μm or less are added to the CaO particles having a particle diameter of 10 μm or more , the bulk CaO is pulverized at the same time as the CaO particles formed by pulverization, A method for producing a CaO-based desulfurization agent, comprising mixing carbonaceous particles and adhering carbonaceous particles to the surface of CaO particles.
  3. 前記炭素質粒子の平均粒径が1μm以下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系脱硫剤の製造方法。   The method for producing a CaO-based desulfurization agent according to claim 1 or 2, wherein an average particle size of the carbonaceous particles is 1 µm or less.
  4. 前記CaO粒子と前記炭素質粒子とを混合した後のCaO粒子の測色計による明度指数L* 値を30以下とすることを特徴とする、請求項1ないし請求項3の何れか1つに記載のCaO系脱硫剤の製造方法。   The lightness index L * value of the CaO particles after mixing the CaO particles and the carbonaceous particles by a colorimeter is set to 30 or less, according to any one of claims 1 to 3. The manufacturing method of CaO type | system | group desulfurization agent of description.
  5. 前記CaO系脱硫剤における前記炭素質粒子の配合率が1質量%以上であ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系脱硫剤の製造方法。 The method for producing a CaO-based desulfurization agent according to any one of claims 1 to 4 , wherein a blending ratio of the carbonaceous particles in the CaO-based desulfurization agent is 1% by mass or more.
  6. 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系脱硫剤の製造方法。 The method for producing a CaO-based desulfurization agent according to any one of claims 1 to 5 , wherein the CaO-based desulfurization agent contains a substance that reacts with CaO to form a low melting point compound. .
  7. 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系脱硫剤の製造方法。 The method for producing a CaO-based desulfurizing agent according to any one of claims 1 to 6 , wherein the CaO-based desulfurizing agent does not contain fluorine.
  8. 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系脱硫剤の製造方法。 The method for producing a CaO-based desulfurization agent according to any one of claims 1 to 7 , wherein the CaO-based desulfurization agent contains a metal substance for deoxidation.
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