JP5045031B2 - Hot metal desulfurization agent and desulfurization treatment method - Google Patents

Hot metal desulfurization agent and desulfurization treatment method Download PDF

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JP5045031B2
JP5045031B2 JP2006228557A JP2006228557A JP5045031B2 JP 5045031 B2 JP5045031 B2 JP 5045031B2 JP 2006228557 A JP2006228557 A JP 2006228557A JP 2006228557 A JP2006228557 A JP 2006228557A JP 5045031 B2 JP5045031 B2 JP 5045031B2
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俊司 大鶴
浩起 藤田
祐一 内田
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JFE Steel Corp
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本発明は、機械攪拌式脱硫装置において溶銑を効率的に脱硫することのできる脱硫剤及び脱硫処理方法に関し、詳しくは、滓化促進剤としてフッ素含有物質を使用しなくとも効率的に脱硫することのできる脱硫剤及び脱硫処理方法に関するものである。   The present invention relates to a desulfurization agent and a desulfurization treatment method capable of efficiently desulfurizing hot metal in a mechanical stirring desulfurization apparatus, and more particularly, to efficiently desulfurize without using a fluorine-containing substance as a hatching accelerator. The present invention relates to a desulfurization agent and a desulfurization treatment method that can be used.

高炉から出銑された溶銑には、通常、鋼の品質に悪影響を及ぼす硫黄(S)が高濃度で含まれており、要求される鋼の品質に応じて、種々の溶銑脱硫及び溶鋼脱硫が行われている。このうち、溶銑の脱硫には、安価なCaO(石灰)を主成分とする脱硫剤が広く用いられており、この場合の脱硫反応は、「CaO+S→CaS+O」に示される反応式に基づいて進行する。   The hot metal discharged from the blast furnace usually contains a high concentration of sulfur (S), which adversely affects the quality of the steel, and various hot metal desulfurization and molten steel desulfurization can be performed depending on the required quality of the steel. Has been done. Among these, for desulfurization of hot metal, inexpensive desulfurization agents mainly composed of CaO (lime) are widely used. In this case, the desulfurization reaction proceeds based on the reaction formula shown by “CaO + S → CaS + O”. To do.

この脱硫処理においては、従来、蛍石(CaF2 )系媒溶剤がCaOの滓化促進剤として使用されており、例えば、CaO源である生石灰に5質量%程度の蛍石を混合したCaO−CaF2系脱硫剤が広く使用されていた。しかしながら、蛍石系媒溶剤は高価であり、蛍石系媒溶剤を配合することは脱硫剤のコスト増大につながり、更に近年、地球環境保全の観点からフッ素(F)の環境への流出が懸念されており、媒溶剤としてフッ素含有物質を使用することは避けることが望まれている。 In this desulfurization treatment, a fluorite (CaF 2 ) -based solvent has been conventionally used as a CaO hatching accelerator. For example, CaO- in which about 5% by mass of fluorite is mixed with quick lime as a CaO source. CaF 2 -based desulfurization agents have been widely used. However, the fluorite-based solvent is expensive, and the addition of the fluorite-based solvent leads to an increase in the cost of the desulfurizing agent, and in recent years, there is a concern about the outflow of fluorine (F) to the environment from the viewpoint of global environmental conservation. Therefore, it is desired to avoid using a fluorine-containing material as a solvent.

蛍石を用いない脱硫剤の一例として、カルシウムカーバイト系の脱硫剤及びソーダ系の脱硫剤が実用化されているが、何れも長所と短所がある。カルシウムカーバイト系の脱硫剤は、強力な脱硫能力を有しているが、脱硫処理後の脱硫スラグの後処理において、アセチレンガスが発生するなどの安全上の問題点がある。また、高価であり、且つ、危険物でもあるため、取り扱いが極めて困難である。ソーダ系の脱硫剤は比較的安価であるが、強アルカリ性であるため、処理炉及び処理容器の耐火物への影響が大きい。また、排ガス中にはNaが含まれるため、その除去処理が必要である。更に、スラグ中のNa2 Oの含有量が高くなるため、セメントなどへの再利用に制約があり、環境への影響からも望ましくない。 As an example of a desulfurizing agent that does not use fluorite, a calcium carbide desulfurizing agent and a soda desulfurizing agent have been put into practical use, both of which have advantages and disadvantages. Calcium carbide-based desulfurization agents have a strong desulfurization ability, but there are safety problems such as the generation of acetylene gas in the post-treatment of the desulfurization slag after the desulfurization treatment. Moreover, since it is expensive and dangerous, it is extremely difficult to handle. A soda-based desulfurization agent is relatively inexpensive, but has a strong alkalinity, and thus has a great influence on the refractories of the processing furnace and the processing vessel. Further, since the exhaust gas contains Na, it is necessary to remove it. Furthermore, since the content of Na 2 O in the slag is high, there is a restriction on the reuse to cement and the like, which is undesirable from the influence on the environment.

これらを考慮すると、CaOを主成分とする脱硫剤は安価で且つ取り扱いも容易であり、そこで、CaOを主成分とする脱硫剤であっても、フッ素含有物質を滓化促進剤として使用しない脱硫剤が提案されている。例えば、特許文献1には、CaO1質量部に対して、Na2 O分を0.02〜0.05質量部、Al23分を0.05〜0.20質量部添加した脱硫剤が提案されている。特許文献1によれば、Al23 の添加によりCaOの滓化が促進され、Al23 の添加による脱硫能力の低下をNa2 Oにより補うことができ、高効率で脱硫処理できるとしている。
特開2001−335820号公報
Considering these, a desulfurization agent mainly composed of CaO is inexpensive and easy to handle. Therefore, even a desulfurization agent mainly composed of CaO does not use a fluorine-containing substance as a hatching accelerator. Agents have been proposed. For example, Patent Document 1 discloses a desulfurization agent in which 0.02 to 0.05 parts by mass of Na 2 O and 0.05 to 0.20 parts by mass of Al 2 O 3 are added to 1 part by mass of CaO. Proposed. According to Patent Document 1, the addition of Al 2 O 3 promotes the hatching of CaO, and the decrease in the desulfurization capacity due to the addition of Al 2 O 3 can be compensated by Na 2 O, so that desulfurization can be performed with high efficiency. Yes.
JP 2001-335820 A

しかしながら、特許文献1で使用するNa2 Oは、生成するスラグの耐火物侵食性を著しく増大させる。このため、特許文献1に提案された脱硫剤を使用した場合には、処理容器の耐火物は著しく溶損し、処理容器の寿命を短くするので、特許文献1に提案された脱硫剤は実用に供し得ないという問題がある。 However, Na 2 O used in Patent Document 1 significantly increases the refractory erosion resistance of the generated slag. For this reason, when the desulfurization agent proposed in Patent Document 1 is used, the refractory in the processing vessel is significantly melted and the life of the processing vessel is shortened. Therefore, the desulfurization agent proposed in Patent Literature 1 is practically used. There is a problem that it cannot be provided.

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、機械攪拌式脱硫装置において溶銑を脱硫するに当たり、フッ素含有物質を滓化促進剤として使用せず、且つ、耐火物の侵食を増大させるNa2 Oも使用せずに、従来のCaO−CaF2 系脱硫剤と同等の脱硫能力を有するCaO系の脱硫剤を提供すると同時に、効率的に脱硫することのできる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, and the object of the present invention is to use no fluorine-containing substance as a hatching accelerator when desulfurizing hot metal in a mechanical stirring desulfurization apparatus, and A desulfurization treatment method capable of efficiently desulfurizing at the same time as providing a CaO-based desulfurization agent having a desulfurization ability equivalent to that of a conventional CaO-CaF 2 desulfurization agent without using Na 2 O that increases erosion Is to provide.

上記課題を解決するための第1の発明に係る溶銑の脱硫剤は、粒径150μm以下の微粉が90質量%以上であるCaO粉体100質量部に対して、Al23 を50質量%以下含有するアルミドロスを5〜20質量部添加したことを特徴とする。 The hot metal desulfurization agent according to the first aspect of the present invention for solving the above-mentioned problems is that 50% by mass of Al 2 O 3 with respect to 100 parts by mass of CaO powder in which fine powder having a particle size of 150 μm or less is 90% by mass or more. 5-20 mass parts of aluminum dross containing below is added, It is characterized by the above-mentioned.

第2の発明に係る溶銑の脱硫処理方法は、第1の発明に記載の溶銑の脱硫剤を、攪拌羽根によって攪拌されている溶銑の浴面に添加し、溶銑を脱硫することを特徴とする。   The hot metal desulfurization treatment method according to the second invention is characterized in that the hot metal desulfurization agent according to the first invention is added to the bath surface of the hot metal being stirred by the stirring blade to desulfurize the hot metal. .

第3の発明に係る溶銑の脱硫処理方法は、第2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銑の浴面に上吹き添加することを特徴とする。   The hot metal desulfurization treatment method according to the third invention is characterized in that, in the second invention, the desulfurizing agent is added by top blowing to the bath surface of the hot metal together with the conveying gas through the top blowing lance.

本発明によれば、脱硫剤であるCaOを、粒径150μm以下の微粉が90質量%以上の粉体とするので、反応界面積が大きくなり、脱硫反応が促進され、脱硫率を向上させることができる。また、CaOは同時に添加されるAl23 により滓化が促進されて、脱硫反応が促進される。これにより、蛍石などのフッ素含有物質を滓化促進剤として使用することなく、効率良く脱硫することもできる。CaOを微粉にすると凝集しやすくなるが、同時に添加されるアルミナ―金属Al混合体によりCaOの凝集が防止され、高い脱硫効率が得られる。即ち、フッ素含有物質を滓化促進剤として使用せずに、且つ、処理容器の溶損を増大させることなく、従来のCaO−CaF2系脱硫剤と同等の脱硫効率を得ることができる。 According to the present invention, CaO, which is a desulfurizing agent, is a powder having a fine particle size of 150 μm or less of 90% by mass or more, so that the reaction interface area is increased, the desulfurization reaction is promoted, and the desulfurization rate is improved. Can do. In addition, the hatching of CaO is promoted by Al 2 O 3 added at the same time, and the desulfurization reaction is promoted. Thereby, it is also possible to efficiently desulfurize without using a fluorine-containing substance such as fluorite as a hatching accelerator. When CaO is made into fine powder, it becomes easy to agglomerate, but the alumina-metal Al mixture added at the same time prevents the aggregation of CaO and provides high desulfurization efficiency. That is, desulfurization efficiency equivalent to that of a conventional CaO—CaF 2 -based desulfurization agent can be obtained without using a fluorine-containing substance as a hatching accelerator and without increasing the melting loss of the processing vessel.

以下、本発明を具体的に説明する。   Hereinafter, the present invention will be specifically described.

蛍石などのフッ素含有物質を滓化促進剤として使用せず、且つ、耐火物の侵食を増大させるNa2 Oも使用せずに、機械攪拌式脱硫装置においてCaO−Al23 系脱硫剤を用いて高い脱硫率を得る方法を検討・研究した。以下に、検討・研究の結果を説明する。 CaO-Al 2 O 3 -based desulfurization agent in a mechanically stirred desulfurization apparatus without using fluorine-containing materials such as fluorite as hatching accelerators and without using Na 2 O which increases erosion of refractories We studied and studied the method of obtaining a high desulfurization rate by using NO. The results of the examination and research are explained below.

攪拌羽根(「インペラー」とも呼ぶ)を備えた機械攪拌式脱硫装置を用いた脱硫処理方法において、脱硫剤は、一般的に攪拌羽根によって強力に攪拌された状態の溶銑上へ、処理容器の上方から連続的に添加される。この場合、脱硫反応を促進させるには、反応界面積が大きいほど有利であり、そこで、脱硫剤となるCaOを微粉化することを検討した。   In a desulfurization treatment method using a mechanical stirring desulfurization apparatus equipped with a stirring blade (also referred to as an “impeller”), the desulfurizing agent is generally placed on the hot metal in a state of being vigorously stirred by the stirring blade, above the processing vessel. Continuously added. In this case, in order to promote the desulfurization reaction, the larger the reaction interface area, the more advantageous. Therefore, it was examined to pulverize CaO as a desulfurization agent.

しかしながら、実際に試験すると、微粉化させたCaOが凝集して、反応界面積の増大効果が得られなかった。この原因を調べるために、生成したスラグを詳細に調査した。その結果、CaOの凝集は、滓化促進剤として添加したAl23 によってCaO−Al23 系の低融点化合物が形成され、これがバインダーとなってCaO粒子同士を凝集させていることが明らかとなった。 However, when actually tested, finely powdered CaO aggregated, and the effect of increasing the reaction interface area was not obtained. In order to investigate this cause, the generated slag was investigated in detail. As a result, the aggregation of CaO is caused by the formation of a CaO-Al 2 O 3 -based low melting point compound by Al 2 O 3 added as a hatching accelerator, which acts as a binder to aggregate CaO particles together. It became clear.

そこで、Al23 源として、Al23 の含有量が50質量%以下であるアルミナ―金属Al混合体を使用したところ、凝集が防止され、高い脱硫率が得られることが分かった。このアルミナ―金属Al混合体としては、アルミドロス(「Al灰」ともいう)が最適である。アルミドロスとは、金属Alを30〜50質量%含有した金属AlとAl23 との混合物であり、他の成分も含有している。アルミナ―金属Al混合体の添加により凝集が防止された理由は、アルミナ―金属Al混合体に含まれるAl23 以外の成分により、低融点化合物の形成が抑制されたことによると考えられる。 Therefore, it was found that when an alumina-metal Al mixture having an Al 2 O 3 content of 50% by mass or less was used as the Al 2 O 3 source, aggregation was prevented and a high desulfurization rate was obtained. As this alumina-metal Al mixture, aluminum dross (also referred to as “Al ash”) is optimal. Almidros is a mixture of metal Al containing 30 to 50% by mass of metal Al and Al 2 O 3, and also contains other components. The reason why aggregation was prevented by the addition of the alumina-metal Al mixture is considered to be because the formation of the low melting point compound was suppressed by components other than Al 2 O 3 contained in the alumina-metal Al mixture.

脱硫剤を微粉化すると、上置き添加の場合には添加時の飛散量が増加し、歩留まりが悪化する。この歩留まり低下を防止するには、微粒の脱硫剤を搬送用ガスとともに溶銑表面に向けて上吹きして添加することで、解決できることが分かった。また、脱硫剤であるCaOは、溶銑との濡れ性が悪く、溶銑中へ巻き込まれにくい上に、浴上へ添加された脱硫剤が、強攪拌されている溶銑の浴表面または浴中で凝集し、反応界面積が低下していく傾向があるが、上吹きして添加することで、これも解消できることが分かった。つまり、上吹き添加により、脱硫剤の歩留まり低下をきたすことなく、脱硫反応界面積を増加させることができることが分かった。   When the desulfurizing agent is pulverized, in the case of top addition, the amount of scattering at the time of addition increases and the yield deteriorates. In order to prevent this decrease in yield, it has been found that a fine desulfurization agent can be solved by adding the carrier gas to the hot metal surface by blowing it upward. Moreover, CaO, which is a desulfurizing agent, has poor wettability with hot metal and is difficult to be caught in hot metal, and the desulfurizing agent added to the bath is agglomerated in the bath surface of the hot metal being strongly stirred or in the bath. However, it has been found that the reaction interface area tends to decrease, but this can also be eliminated by adding it by top blowing. In other words, it was found that the desulfurization reaction interfacial area can be increased without lowering the yield of the desulfurizing agent by adding the top blowing.

尚、この場合の搬送用ガスは、脱硫反応が還元反応であることから、酸素を含有しないガス、例えば窒素ガスであることが好ましい。また、上吹きによって溶銑の浴面に吹き付けた脱硫剤が溶銑の内部まで侵入すると、溶銑中に巻き込まれやすく、脱硫反応にとって望ましいので、そのような条件になるように、上吹きランス出口でのガス流速を調整することが好ましい。   In this case, the carrier gas is preferably a gas not containing oxygen, for example, nitrogen gas, because the desulfurization reaction is a reduction reaction. In addition, if the desulfurizing agent sprayed on the hot metal bath surface by top blowing enters the hot metal, it is easy to get caught in the hot metal, which is desirable for the desulfurization reaction. It is preferable to adjust the gas flow rate.

本発明に係る溶銑の脱硫剤及び脱硫処理方法は上記の検討・研究の結果に基づきなされたものである。つまり、発明に係る溶銑の脱硫剤は、粒径150μm以下の微粉が90質量%以上であるCaO粉体100質量部に対して、Al23 を50質量%以下含有するアルミナ―金属Al混合体を5〜20質量部添加したことを特徴としている。 The hot metal desulfurization agent and the desulfurization processing method according to the present invention are based on the results of the above examination and research. That is, the hot metal desulfurization agent according to the present invention is an alumina-metal Al mixture containing 50% by mass or less of Al 2 O 3 with respect to 100 parts by mass of CaO powder having a fine particle size of 150 μm or less of 90% by mass or more. It is characterized by adding 5 to 20 parts by mass of the body.

この場合のCaOの粒度分布条件は、後述する実施例に基づくものである。また、アルミナ―金属Al混合体の添加量が5質量部未満の場合には、Al23 による滓化促進効果が得られず、一方、アルミナ―金属Al混合体の添加量が20質量部を超える場合には、CaO濃度が薄まり、脱硫効率が低下するからである。ここで粒径150μm以下とは、篩分器の目開き寸法で定義したもので、長径が150μmを超えても、目開き寸法が150μmの篩分器を通過する限り、粒径150μm以下と定義する。 The CaO particle size distribution conditions in this case are based on the examples described later. Further, when the addition amount of the alumina-metal Al mixture is less than 5 parts by mass, the effect of promoting the hatching by Al 2 O 3 cannot be obtained, while the addition amount of the alumina-metal Al mixture is 20 parts by mass. This is because the CaO concentration decreases and the desulfurization efficiency decreases. Here, the particle size of 150 μm or less is defined by the sieve size of the sieving device. Even if the major axis exceeds 150 μm, the particle size is defined as 150 μm or less as long as it passes through a sieving machine having a mesh size of 150 μm. To do.

次に、図面を参照して本発明に係る溶銑の脱硫処理方法を説明する。当然ながら、本発明に係る溶銑の脱硫処理方法では脱硫剤として本発明に係る脱硫剤を使用する。   Next, the hot metal desulfurization method according to the present invention will be described with reference to the drawings. Naturally, in the hot metal desulfurization treatment method according to the present invention, the desulfurization agent according to the present invention is used as the desulfurization agent.

図1は、本発明に係る脱硫処理方法の1例を示す側面概略図であり、図1は、溶銑を収容する処理容器として取鍋型の溶銑鍋を使用した例を示している。処理容器の形状については、機械攪拌式脱硫装置で脱硫処理を行うことから、図1に示すように取鍋型の処理容器が最適であるが、トーピードカーにおいても使用可能である。以下、処理容器として溶銑鍋を使用した例で説明する。   FIG. 1 is a schematic side view showing an example of the desulfurization processing method according to the present invention, and FIG. 1 shows an example in which a ladle type hot metal ladle is used as a processing container for containing hot metal. As for the shape of the processing container, a ladle-type processing container is optimal as shown in FIG. 1 because desulfurization is performed by a mechanical stirring desulfurization apparatus, but it can also be used in a torpedo car. Hereinafter, an example in which a hot metal ladle is used as the processing container will be described.

高炉から出銑された溶銑3を台車1に搭載された溶銑鍋2またはトーピードカーで受銑し、受銑した溶銑3を機械攪拌式脱硫装置に搬送する。トーピードカーで受銑した場合には、脱硫処理に先立ち、取鍋型の処理容器に移し替えることが望ましい。本発明による脱硫処理の対象となる溶銑3は、どのような成分であっても構わず、例えば、予め脱珪処理や脱燐処理が施されていてもよい。脱珪処理とは、脱燐処理を効率良く行うために脱燐処理に先立ち、溶銑3に酸素ガスや鉄鉱石などの酸素源を添加して主に溶銑中のSiを除去する処理である。   The hot metal 3 discharged from the blast furnace is received by the hot metal ladle 2 or the torpedo car mounted on the carriage 1, and the received hot metal 3 is conveyed to a mechanical stirring desulfurization apparatus. When it is received by a torpedo car, it is desirable to transfer to a ladle type processing container prior to the desulfurization process. The hot metal 3 to be subjected to the desulfurization treatment according to the present invention may be any component, and for example, desiliconization treatment or dephosphorization treatment may be performed in advance. The desiliconization process is a process for mainly removing Si in the hot metal by adding an oxygen source such as oxygen gas or iron ore to the hot metal 3 prior to the dephosphorization process in order to efficiently perform the dephosphorization process.

機械攪拌式脱硫装置は、溶銑鍋2に収容された溶銑3に浸漬・埋没し、旋回して溶銑3を攪拌するための耐火物製の攪拌羽根4を備えており、この攪拌羽根4は、昇降装置(図示せず)によってほぼ鉛直方向に昇降し、且つ、回転装置(図示せず)によって軸4aを回転軸として旋回するようになっている。また、機械攪拌式脱硫装置には、本発明に係る脱硫剤7を、溶銑鍋2に収容された溶銑3に向けて上吹きして添加するための上吹きランス5が設置されている。また、本発明に係る脱硫剤7を、溶銑鍋2に収容された溶銑3の浴面に上置き添加するための投入口6も設置されている。つまり、脱硫剤7を上吹きランス5から吹き付けて添加することも、上置き添加することもどちらもできるようになっている。更に、溶銑鍋2の上方位置には、集塵機(図示せず)に接続する排気ダクト口(図示せず)が備えられ、脱硫処理中に発生するガスやダストが排出されるようになっている。尚、脱硫剤7は、CaO粉体とアルミナ―金属Al混合体とが所定の配合比率で予め混合されたものである。   The mechanical stirring-type desulfurization apparatus includes a refractory stirring blade 4 that is immersed and buried in a hot metal 3 accommodated in a hot metal ladle 2 and swirls to stir the hot metal 3. It is moved up and down in a substantially vertical direction by an elevating device (not shown), and is turned around a shaft 4a as a rotating shaft by a rotating device (not shown). Further, the mechanical stirring type desulfurization apparatus is provided with an upper blowing lance 5 for adding the desulfurizing agent 7 according to the present invention by blowing up toward the hot metal 3 accommodated in the hot metal ladle 2. Moreover, the inlet 6 for adding the desulfurization agent 7 which concerns on this invention on the bath surface of the hot metal 3 accommodated in the hot metal ladle 2 is also installed. That is, the desulfurizing agent 7 can be added by spraying from the top blowing lance 5 or can be added on top. Further, an exhaust duct port (not shown) connected to a dust collector (not shown) is provided at an upper position of the hot metal ladle 2 so that gas and dust generated during the desulfurization process are discharged. . The desulfurizing agent 7 is prepared by previously mixing CaO powder and an alumina-metal Al mixture at a predetermined mixing ratio.

上吹きランス5は、粉体状の脱硫剤7を収容するホッパー8とホッパー8から定量切り出すための切り出し装置9とからなる供給装置と接続しており、上吹きランス5から、搬送用ガスとともに、粉体状の脱硫剤7を任意のタイミングで供給できる構造になっている。当然ながら、搬送用ガスのみを上吹きすることもできる構造になっている。   The top blowing lance 5 is connected to a supply device including a hopper 8 that contains the powdery desulfurizing agent 7 and a cutting device 9 for quantitatively cutting out from the hopper 8. The powdery desulfurizing agent 7 can be supplied at an arbitrary timing. Of course, it has a structure in which only the carrier gas can be blown up.

この場合に、上吹きランス5は、単孔でもよいし、溶銑湯面における吹き付け面積を増加させるなどの目的で多孔化してもよい。また、上吹きランス5の吹き付け角度、つまり、上吹きランス5から脱硫剤7を溶銑浴面に吹き付ける角度は、鉛直方向のみならず、攪拌中の溶銑湯面(盛り上がって渦が形成されているため、水平面に対しては傾斜した角度を持つ)に対して垂直に供給することも可能であり、また、鉛直方向と湯面に垂直な方向との間の任意の角度で上吹き添加することができるようになっている。   In this case, the top blowing lance 5 may be a single hole or may be made porous for the purpose of increasing the spraying area on the surface of the molten metal. Moreover, the spray angle of the top blowing lance 5, that is, the angle at which the desulfurizing agent 7 is sprayed from the top blowing lance 5 onto the hot metal bath surface is not limited to the vertical direction, and the hot metal surface during stirring (swells and vortices are formed). Therefore, it is possible to supply perpendicularly with respect to the horizontal plane), and to add up at an arbitrary angle between the vertical direction and the direction perpendicular to the molten metal surface Can be done.

投入口6は、粉体状の脱硫剤7を収容するホッパー10とホッパー10から定量切り出すためのロータリーフィーダー11とからなる供給装置と接続しており、投入口6から、脱硫剤7を任意のタイミングで供給できる構造になっている。   The input port 6 is connected to a supply device including a hopper 10 containing the powdered desulfurizing agent 7 and a rotary feeder 11 for quantitatively cutting out from the hopper 10, and the desulfurizing agent 7 is optionally supplied from the input port 6. It has a structure that can be supplied at the timing.

攪拌羽根4の位置が溶銑鍋2のほぼ中心になるように、溶銑鍋2を搭載した台車1の位置を調整し、次いで、攪拌羽根4を下降させて溶銑3に浸漬させる。攪拌羽根4が溶銑3に浸漬したならば、攪拌羽根4の旋回を開始し、所定の回転数まで昇速する。攪拌羽根4の回転数が所定の回転数に達したならば、切り出し装置9を起動させて、ホッパー8に収容された脱硫剤7を、搬送用ガスとともに溶銑3の浴面に向けて上吹きランス5から吹き付けて添加する。搬送用ガスとしては、還元性のガス、不活性ガスまたは非酸化性ガスを使用する。脱硫剤7を上吹きランス5から吹き付けて添加する代わりに、投入口6から上置き添加することも可能であるが、前述したように、脱硫剤7の歩留まりが高い、脱硫反応界面積を増加させることができるなどの利点から、上吹きランス5から吹き付けて添加することが好ましい。   The position of the carriage 1 on which the hot metal ladle 2 is mounted is adjusted so that the position of the stirring blade 4 is substantially at the center of the hot metal ladle 2, and then the stirring blade 4 is lowered and immersed in the hot metal 3. If the stirring blade 4 is immersed in the hot metal 3, the stirring blade 4 starts to turn and the speed is increased to a predetermined rotational speed. When the rotational speed of the stirring blade 4 reaches a predetermined rotational speed, the cutting device 9 is started and the desulfurizing agent 7 accommodated in the hopper 8 is blown upward toward the bath surface of the hot metal 3 together with the conveying gas. Spray from lance 5 and add. As the carrier gas, a reducing gas, an inert gas or a non-oxidizing gas is used. Instead of adding the desulfurizing agent 7 by spraying from the top blowing lance 5, it is possible to add the desulfurizing agent 7 from the inlet 6, but as described above, the yield of the desulfurizing agent 7 is high and the desulfurization reaction interfacial area is increased. It is preferable to add by spraying from the top blowing lance 5 from the advantage that it can be made.

所定量の脱硫剤7を添加完了し、そして、所定時間の攪拌が行われたなら、攪拌羽根4の回転数を減少させ停止させる。攪拌羽根4の旋回が停止したなら、攪拌羽根4を上昇させ、溶銑鍋2の上方に待機させる。生成したスラグが浮上して溶銑表面を覆い、静止した状態で溶銑3の脱硫処理が終了する。脱硫処理後、生成したスラグを溶銑鍋2から排出し、次の精錬工程に溶銑鍋2を搬送する。   When the addition of a predetermined amount of the desulfurizing agent 7 is completed and stirring is performed for a predetermined time, the rotational speed of the stirring blade 4 is decreased and stopped. When the swirling of the stirring blade 4 is stopped, the stirring blade 4 is lifted and waited above the hot metal pan 2. The generated slag floats to cover the hot metal surface, and the desulfurization process of the hot metal 3 is completed in a stationary state. After the desulfurization treatment, the generated slag is discharged from the hot metal ladle 2 and conveyed to the next refining process.

以上説明したように、本発明によれば、脱硫剤であるCaOを、粒径150μm以下の微粉が90質量%以上の粉体とするので、反応界面積が大きくなり、脱硫反応が促進され、脱硫率を向上させることができる。また、CaOは同時に添加されるAl23 により滓化が促進されて、脱硫反応が促進される。即ち、フッ素含有物質を滓化促進剤として使用せずに、且つ、処理容器の溶損を増大させることなく、従来のCaO−CaF2系脱硫剤と同等の脱硫効率を得ることができる。 As described above, according to the present invention, CaO, which is a desulfurizing agent, is a fine particle having a particle size of 150 μm or less and a powder having a mass of 90% by mass or more, so that the reaction interfacial area is increased and the desulfurization reaction is promoted. The desulfurization rate can be improved. In addition, the hatching of CaO is promoted by Al 2 O 3 added at the same time, and the desulfurization reaction is promoted. That is, desulfurization efficiency equivalent to that of a conventional CaO—CaF 2 -based desulfurization agent can be obtained without using a fluorine-containing substance as a hatching accelerator and without increasing the melting loss of the processing vessel.

本発明方法を用いて溶銑鍋内の約300トンの溶銑を図1に示す機械攪拌式脱硫装置で脱硫処理した例を説明する。   A description will be given of an example in which about 300 tons of hot metal in the hot metal ladle is desulfurized using the mechanical stirring type desulfurization apparatus shown in FIG.

処理対象の溶銑は、高炉から出銑した後、高炉鋳床で脱珪処理を行ったものを用いた。溶銑組成は、事前の脱珪処理により、C:4.1〜4.5質量%、Si:0.13〜0.20質量%、Mn:0.15〜0.25質量%、P:0.9〜1.3質量%、S:0.02〜0.03質量%であった。溶銑温度は、1300〜1350℃であった。   The hot metal to be treated was one that was removed from the blast furnace and then desiliconized on the blast furnace casting floor. The hot metal composition was C: 4.1 to 4.5% by mass, Si: 0.13 to 0.20% by mass, Mn: 0.15 to 0.25% by mass, P: 0 by prior desiliconization treatment. It was 0.9-1.3 mass%, S: 0.02-0.03 mass%. The hot metal temperature was 1300 to 1350 ° C.

使用する脱硫剤は、生石灰(CaO)を粉砕し、粒径150μm以下が90質量%になるように調製したCaO粉体100質量部に対して、Al23 を40質量%含有するアルミドロスを10質量部添加・混合したものを用いた。この脱硫剤を上吹きランスから窒素ガスを搬送用ガスとして溶銑浴面に吹き付けて脱硫処理した。その結果、処理後のS濃度が0.002〜0.005質量%で、温度が1280〜1330℃の溶銑を安定して得ることができた。 The desulfurization agent used is aluminum dross containing 40% by mass of Al 2 O 3 with respect to 100 parts by mass of CaO powder prepared by pulverizing quick lime (CaO) so that the particle size is 150 μm or less. 10 parts by mass of added and mixed was used. This desulfurizing agent was desulfurized by spraying nitrogen gas from the top blowing lance onto the hot metal bath surface as a carrier gas. As a result, it was possible to stably obtain hot metal having an S concentration of 0.002 to 0.005% by mass and a temperature of 1280 to 1330 ° C. after the treatment.

本発明に係る脱硫処理方法の1例を示す側面概略図である。It is a side surface schematic diagram showing an example of a desulfurization processing method concerning the present invention.

符号の説明Explanation of symbols

1 台車
2 溶銑鍋
3 溶銑
4 攪拌羽根
5 上吹きランス
6 投入口
7 脱硫剤
8 ホッパー
9 切り出し装置
10 ホッパー
11 ロータリーフィーダー
DESCRIPTION OF SYMBOLS 1 Bogie 2 Hot metal ladle 3 Hot metal 4 Stirrer blade 5 Top blowing lance 6 Loading port 7 Desulfurizing agent 8 Hopper 9 Cutting device 10 Hopper 11 Rotary feeder

Claims (3)

粒径150μm以下の微粉が90質量%以上であるCaO粉体100質量部に対して、Al23 を50質量%以下含有するアルミドロスを5〜20質量部添加したことを特徴とする、溶銑の脱硫剤。 5 to 20 parts by mass of aluminum dross containing 50% by mass or less of Al 2 O 3 is added to 100 parts by mass of CaO powder in which fine powder having a particle size of 150 μm or less is 90% by mass or more, Hot metal desulfurization agent. 請求項1に記載の溶銑の脱硫剤を、攪拌羽根によって攪拌されている溶銑の浴面に添加し、溶銑を脱硫することを特徴とする、溶銑の脱硫処理方法。   A hot metal desulfurization method according to claim 1, wherein the hot metal desulfurization agent according to claim 1 is added to the bath surface of the hot metal being stirred by a stirring blade to desulfurize the hot metal. 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銑の浴面に上吹き添加することを特徴とする、請求項2に記載の溶銑の脱硫処理方法。   3. The hot metal desulfurization method according to claim 2, wherein the desulfurizing agent is added to the hot metal bath surface together with a carrier gas through an upper blow lance.
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