JP4923662B2 - Method for adjusting fluidity of slag in storage furnace - Google Patents
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Description
本発明は、貯銑炉内スラグの流動性調整方法に係わり、詳しくは、溶銑又は溶融還元炉にて溶製した含Ｃｒ溶鉄を貯銑又は貯鉄する加熱装置を備えた貯銑炉において、炉内に滞留するスラグの量を著しく低減し、該貯銑炉の内張り耐火物の侵食が減り、貯銑炉の寿命を延長する技術に関する。 The present invention relates to a method for adjusting the fluidity of slag in a storage furnace, and more specifically, in a storage furnace including a heating device for storing or storing Cr-containing molten iron melted in a hot metal or a smelting reduction furnace, The present invention relates to a technique for significantly reducing the amount of slag staying in the furnace, reducing the erosion of the refractory lining the storage furnace, and extending the life of the storage furnace.
高炉から出銑された溶銑は、混銑車や溶銑鍋に受け、脱燐及び脱硫等の予備処理が施されてから、予め鉄スクラップ（以下、単にスクラップという）等が投入されている転炉に装入し、上吹きランス等を介して酸素ガスを吹きつけて脱炭精錬を行い、溶鋼を溶製している。 The hot metal discharged from the blast furnace is received in a kneading car or hot metal ladle, subjected to pretreatment such as dephosphorization and desulfurization, and then into a converter to which iron scrap (hereinafter simply referred to as scrap) has been put in advance. The steel is charged and decarburized and refined by blowing oxygen gas through an upper blowing lance, etc., and molten steel is produced.
ところで、前記した混銑車と転炉とは、その容量が釣り合わないのが一般的である。そのため、混銑車や溶銑鍋等に保持している溶銑は、転炉への溶銑の払い出し待機中に温度低下が生じる。また、混銑車や溶銑鍋から転炉への供給量が不足すると、転炉の安定、あるいは円滑な操業ができなくなるという問題も生じる。従来は、かかる問題に対処するため、図５に示すような貯銑炉１と称する炉を別に準備し、転炉へ払い出し前の溶銑２の量の確保及び成分の調整を行うことが行われている。なお、貯銑炉１には、加熱装置３が備えられており、溶銑の温度低下の防止に加え、必要に応じてスクラップの事前溶解及び溶銑の成分調整にも有効に利用されている。また、ステンレス鋼を転炉で溶製するには、母溶湯として、転炉型溶融還元炉にてＣｒ鉱石を炭材で溶融還元して予め含Ｃｒ溶鉄を溶製しているが、この含Ｃｒ溶鉄も該貯銑炉を有効に利用している。
By the way, it is general that the capacities of the above-described chaotic wheel and converter are not balanced. For this reason, the temperature of the hot metal held in the kneading wheel, the hot metal ladle or the like is lowered while waiting for the hot metal to be discharged to the converter. Moreover, when the supply amount from the kneading wheel or the hot metal ladle to the converter is insufficient, there arises a problem that the converter cannot be stably or smoothly operated. Conventionally, in order to cope with such a problem, a separate furnace called a
しかしながら、加熱装置を用いて貯銑炉内で、スクラップを炉内で溶解する過程において、不可避的にスクラップが含有する金属成分の酸化が生じ、炉内に滞留するスラグの量が増加する。このスラグの増加は、耐火物とスラグとの接触面積を増加させるため、必然的に、スラグによって侵食される面積が増加する。その結果、耐火物の損耗量を増加して、炉体寿命が短くなる。 However, in the process of melting the scrap in the storage furnace using the heating device, the metal components contained in the scrap inevitably oxidize, and the amount of slag staying in the furnace increases. Since the increase in the slag increases the contact area between the refractory and the slag, the area eroded by the slag is inevitably increased. As a result, the amount of wear of the refractory is increased, and the lifetime of the furnace body is shortened.
一方、貯銑炉の耐火物がスラグによって侵食されるのを回避するには、貯銑炉内に滞留するスラグの塩基度（スラグ中のＣａＯとＳｉＯ２との質量比：ＣａＯ／ＳｉＯ２で表す）を１．０以上とすることが望ましいと言われている。そして、造滓材として石灰等のＣａＯ源や珪石等のＳｉＯ２源を別途添加して、スラグの塩基度調整を実施している。 On the other hand, in order to avoid the refractory of the storage furnace being eroded by the slag, the basicity of the slag staying in the storage furnace (mass ratio of CaO and SiO 2 in the slag: CaO / SiO 2 It is said that it is desirable to set it to 1.0 or more. Then, a CaO source such as lime and a SiO 2 source such as silica stone are separately added as a koji material to adjust the basicity of slag.
ところが、この方法は、スラグの量をさらに増加させるので、スクラップを溶解する加熱装置を備えた貯銑炉にとっては有効な手段ではない。また、スラグの増加は、スクラップを貯銑炉に投入した際に、その表面にスラグが付着したり、あるいはスラグの上にスクラップが浮遊するので、溶銑からスクラップへの浸炭が阻害され、スクラップの溶解速度が著しく低下するという問題も生じる。 However, since this method further increases the amount of slag, it is not an effective means for a storage furnace equipped with a heating device for melting scrap. In addition, the increase in slag is due to the fact that when slag is thrown into the storage furnace, slag adheres to the surface of the slag, or the scrap floats on the slag. Another problem is that the dissolution rate is significantly reduced.
そこで、珪石又は珪素鋼板屑の添加で塩基度を０．８〜２．０に調整して、スラグを低融点にすると共に、流動性（スラグは固液共存状態なので、粘度ではない。従って、以後、炉からの排出性ともいうことあり）を確保し、且つＡ１灰やＡ１２０３源の添加で、該スラグのＡ１２０３含有量を５〜１５質量％として、スラグの滓化を維持する操業方法が開示された（例えば、特許文献１参照）。
しかしながら、特許文献１記載の方法も、炉内への珪石やＡｌ２０３源等の造滓材を添加するため、貯銑炉内スラグの増量は回避できない。また、スラグの塩基度は、０．８〜２．０に調整するのが望ましいと記載されているが、スラグの前記流動性を確保するには、一層低い０．８以下がより望ましい。ところが、特許文献１には、０．８以下の低塩基度で、耐火物の溶損を抑制する手段も実施例も記載されていない。
However, the method described in
本発明は、かかる事情に鑑み、溶銑又は溶融還元炉にて溶製した含Ｃｒ溶鉄を貯銑又は貯鉄する加熱装置を備えた貯銑炉において、炉内に滞留するスラグの量を著しく低減し、該貯銑炉の内張り耐火物の侵食が減り、貯銑炉の寿命を延長可能な貯銑炉内スラグの流動性調整方法を提供することを目的としている。 In view of such circumstances, the present invention remarkably reduces the amount of slag retained in the furnace in a storage furnace equipped with a heating device for storing or storing Cr-containing molten iron melted in a hot metal or smelting reduction furnace. Another object of the present invention is to provide a method for adjusting the fluidity of the slag in the storage furnace that can reduce the erosion of the refractory lining the storage furnace and extend the life of the storage furnace.
発明者は、上記目的を達成するため鋭意研究を重ね、その成果を本発明に具現化した。 The inventor has intensively studied to achieve the above object, and the results have been embodied in the present invention.
すなわち、本発明は、加熱手段を備えた貯銑炉内に保持した溶鉄へ鉄スクラップを投入して溶解させ、該溶鉄の保持量を増加させるに際して、炉内に残留するスラグにＳｉを含有する合金鉄を投入し、該スラグ中に含まれる低級酸化物の濃度を低下して、炉からのスラグの排出性を高めることを特徴とする貯銑炉内スラグの流動性調整方法である。 That is, according to the present invention, when iron scrap is charged and melted in molten iron held in a storage furnace equipped with heating means, and the retained amount of the molten iron is increased, the slag remaining in the furnace contains Si. This is a method for adjusting the fluidity of slag in a storage furnace, wherein alloyed iron is introduced and the concentration of lower oxides contained in the slag is lowered to improve the slag discharge from the furnace.
この場合、前記合金鉄の投入で、前記溶鉄中のＳｉ含有量を０．０５〜０．３０質量％に調整するのが良い。また、前記加熱手段を、誘導加熱装置としたり、あるいは前記低級酸化物を、Ｆｅ、Ｃｒ及びＭｎの酸化物とするのが好ましい。さらに、前記溶鉄を、予備脱珪処理、予備脱燐処理及び／若しくは予備脱硫処理を施された溶銑、又はクロム鉱石の溶融還元で溶製した含クロム溶鉄とするのが良い。 In this case, the Si content in the molten iron is preferably adjusted to 0.05 to 0.30% by mass by introducing the alloy iron. The heating means is preferably an induction heating device, or the lower oxide is preferably an oxide of Fe, Cr and Mn. Further, the molten iron may be a hot metal which has been subjected to preliminary desiliconization treatment, preliminary dephosphorization treatment and / or preliminary desulfurization treatment, or chromium-containing molten iron produced by smelting reduction of chromium ore.
本発明では、貯銑炉内のスラグにＳｉ源等を還元剤として投入し、スラグの固化要因であるスラグ中のＦｅＯやＣｒ２０３等を優先的に還元するようにしたので、所謂「造滓材」でのスラグの成分調整をすることなく、炉からのスラグの排出性を高め、前記貯銑炉から溶銑を払い出す際に、同時に排出されるスラグの量を増加できるようになる。その結果、貯銑炉内に滞留するスラグの量が低減し、内張り耐火物の侵食が減り、貯銑炉の寿命が延長する。 In the present invention, Si source or the like is introduced as a reducing agent into the slag in the storage furnace so that FeO, Cr 2 O 3 and the like in the slag, which are solidification factors of the slag, are preferentially reduced. Without adjusting the slag component in the slag material, the slag discharge from the furnace can be improved, and the amount of slag discharged at the same time can be increased when the hot metal is discharged from the storage furnace. . As a result, the amount of slag staying in the storage furnace is reduced, the erosion of the lining refractory is reduced, and the life of the storage furnace is extended.
以下、発明をなすに至った経緯をまじえ、本発明の最良の実施形態を説明する。 Hereinafter, the best embodiment of the present invention will be described based on the background of the invention.
現在、ステンレス鋼を転炉で溶製するために、母溶湯として、転炉型溶融還元炉にてＣｒ鉱石を炭材で溶融還元して予め含Ｃｒ溶鉄を溶製し、誘導加熱装置を備えた貯銑炉に保持し、スクラップ、合金鉄等のさらなる溶解を行って、溶鉄量の増加や成分調整を行ってから、転炉へ必要に応じた量を払い出すようにしている。この貯銑炉の寿命は、炉内のスラグラインに相当する位置の耐火物が激しく損耗し、ある炉代では目標とする寿命の１７％という短命に終わった。この炉代を以下「第１の炉代」と呼ぶ。 Currently, in order to melt stainless steel in a converter, as a mother molten metal, Cr ore is melt-reduced with carbonaceous material in a converter-type smelting reduction furnace, and Cr-containing molten iron is melted in advance, and an induction heating device is provided. It is held in a storage furnace, and scrap, alloy iron, etc. are further melted to increase the amount of molten iron and adjust the components, and then the required amount is delivered to the converter. The life of the storage furnace was severely worn by the refractory at the position corresponding to the slag line in the furnace, and the life of the furnace was short at 17% of the target life in a certain furnace cost. This furnace cost is hereinafter referred to as “first furnace cost”.
そこで、発明者は、その原因について鋭意検討を重ね、０．２〜０．６という低塩基度のスラグ形成を回避するため、炉内へ石灰（ＣａＯ）源を投入したことによると推定した。つまり、スラグへの石灰（ＣａＯ）源の投入で、スラグ量が著しく増加したのである。また、その投入に際しては、スラグの塩基度を１．５とするのを目標としていたが、サンプリングしたスラグの分析調査では、全てのスラグ試料で塩基度が１.０以下（０．６〜０．８）と目標の塩基度まで上昇していない。これは、貯銑炉に別途投入した脱珪処理されていない溶銑等の高Ｓｉ源が、炉内で酸化して予想外のＳｉＯ２が発生したためと思われるが、このことも、炉内に存在するスラグの増量要因であった。 Therefore, the inventor has conducted intensive studies on the cause and estimated that the lime (CaO) source was introduced into the furnace in order to avoid the formation of slag having a low basicity of 0.2 to 0.6. In other words, the amount of slag increased significantly with the introduction of lime (CaO) source into the slag. In addition, the goal was to set the basicity of the slag to 1.5 at the time of introduction, but in the analysis survey of the sampled slag, the basicity of all slag samples was 1.0 or less (0.6 to 0). .8) and the target basicity has not increased. This is thought to be due to the fact that high Si sources such as hot metal that had not been subjected to desiliconization, which were separately supplied to the storage furnace, were oxidized in the furnace, and unexpected SiO 2 was generated. This also occurred in the furnace. It was an increase factor of the existing slag.
次いで、次なる炉代（この炉代を以下「第２の炉代」と呼ぶ」）の操業に際し、発明者は、スラグの塩基度を調整する方法の採用は得策でないと考え、スラグ量を徹底して低減することにした。そして、炉内スラグのインプット量及びアウトプット量を日々管理したところ、炉内スラグの排出量が増加するのは、貯銑炉内に保持した溶鉄のＳｉが上昇した時であることに気がついた。具体的には、通常時には０．０３質量％以下であるのが、０．０７質量％以上になると、スラグの排出量が多くなったのである。なお、この時の炉内スラグの特徴としては、Ｔ．Ｆｅ及びＴ・Ｃｒの含有量が低いという現象が観察された。 Next, in the operation of the next furnace cost (this furnace cost is hereinafter referred to as “second furnace cost”), the inventor considered that the adoption of a method of adjusting the basicity of the slag was not a good idea, and the amount of slag was reduced. We decided to reduce it thoroughly. Then, when the input amount and the output amount of the slag in the furnace were managed every day, it was found that the discharge amount of the slag in the furnace increased when the Si of the molten iron held in the storage furnace increased. . Specifically, it is 0.03% by mass or less at normal times, but when it is 0.07% by mass or more, the amount of slag discharged is increased. As a feature of the in-furnace slag at this time, T.W. The phenomenon that the content of Fe and T · Cr was low was observed.
そこで、炉内スラグが固化、又は増加し始めたタイミングにおいて、炉内へＳｉ源としてＳｉ含有量の多いフェロクロム（Ｓｉ＝１〜４質量％）を添加したところ、溶鉄の払い出しに際してスラグの排出量が著しく増加し、炉内に残留する量の低減が確認された。その理由は、スラグが含有するＦｅ酸化物、Ｃｒ酸化物及びＭｎ酸化物等の所謂「低級酸化物」が、下式で示す反応によってＳｉで還元されるため、スラグ量が減少するからである。 Therefore, at the timing when the slag in the furnace began to solidify or increase, ferrochrome (Si = 1 to 4% by mass) with a high Si content was added to the furnace as the Si source, and the amount of slag discharged when the molten iron was discharged. Was significantly increased, and a reduction in the amount remaining in the furnace was confirmed. The reason is that so-called “lower oxides” such as Fe oxide, Cr oxide and Mn oxide contained in slag are reduced by Si by the reaction shown in the following formula, so that the amount of slag is reduced. .
２（ＦｅＯ）＋［Ｓｉ］＝２［Ｆｅ］＋（ＳｉＯ２）・・ （１）
２（Ｃｒ２０３）＋３［Ｓｉ］＝４［Ｃｒ］＋３（ＳｉＯ２） （２）
２（ＭｎＯ）＋［Ｓｉ］＝２［Ｍｎ］＋（ＳｉＯ２） （３）
ここで、（）はスラグ中の成分を、［］は溶鉄中の成分をであることを表す。
2 (FeO) + [Si] = 2 [Fe] + (SiO 2 ) (1)
2 (Cr 2 0 3 ) +3 [Si] = 4 [Cr] +3 (SiO 2 ) (2)
2 (MnO) + [Si] = 2 [Mn] + (SiO 2 ) (3)
Here, () represents a component in slag, and [] represents a component in molten iron.
かかる（１）〜（３）の還元反応で発生するＳｉＯ２は、貯銑炉内のスラグの塩度度を低下させるために、その流動性を増し、溶鉄払い出し時でのスラグの排出性が向上する。 The SiO 2 generated in the reduction reactions (1) to (3) increases the fluidity in order to reduce the salinity of the slag in the storage furnace, and the slag discharge property when discharging molten iron is increased. improves.
なお、上記ＳｉＯ２の生成量は、前記した従来技術でスラグの塩基度調整に添加する石灰源の量に比べ、著しく少ないので、スラグを増量する主な要因にはならない。また、本発明の実施で生じるような低塩基度のスラグは、従来より耐火物損傷への影響が危惧されてきたが、貯銑炉内のスラグ量を削減することによって、その有害性は著しく抑制されたのである。 Note that the amount of SiO 2 produced is significantly smaller than the amount of lime source added to adjust the basicity of slag in the above-described prior art, and therefore does not become a main factor for increasing the amount of slag. In addition, low basicity slag as produced in the practice of the present invention has been concerned about the impact on refractory damage from the past, but by reducing the amount of slag in the storage furnace, its harmfulness is significant. It was suppressed.
さらに、本発明では、前記ＦｅＣｒの添加は、貯銑炉内においてスラグが溶鉄の表面全体を覆っているタイミングで行うのが望ましい。表面を覆っていない状態では、溶鉄中のＳｉが雰囲気中の酸素によって下記の反応によって酸化され、スラグ中のＳｉＯ２量を必要以上に増加させるマイナス面があるからである。 Furthermore, in the present invention, it is desirable to add the FeCr at a timing when the slag covers the entire surface of the molten iron in the storage furnace. This is because, in a state where the surface is not covered, Si in the molten iron is oxidized by oxygen in the atmosphere by the following reaction, and there is a negative aspect that increases the amount of SiO 2 in the slag more than necessary.
［Ｓｉ］＋Ｏ２＝（ＳｉＯ２）・・ （４）
本発明は、以上述べた事実を要件に完成させたものであり、具体的には、加熱手段を備えた貯銑炉内に保持した溶鉄へ鉄スクラップを投入して溶解させ、該溶鉄の保持量を増加させるに際して、炉内に残留するスラグにＳｉを含有する合金鉄を投入し、該スラグ中に含まれる低級酸化物の濃度を低下して、スラグの減量を図ると共に、炉からの排出性を高めることを特徴としている。また、スラグ中のＦｅやＣｒ等の有価金属は溶鉄に移行するため、本発明は、経済的にも有利である。
[Si] + O 2 = (SiO 2 ) (4)
The present invention has been completed based on the above-mentioned facts, and specifically, iron scrap is charged into molten iron held in a storage furnace equipped with heating means, and the molten iron is retained. When increasing the amount, iron alloy containing Si is introduced into the slag remaining in the furnace, and the concentration of lower oxides contained in the slag is reduced to reduce the slag and discharge from the furnace. It is characterized by enhancing sex. Moreover, since valuable metals, such as Fe and Cr in slag, transfer to molten iron, the present invention is economically advantageous.
なお、前述の第１の炉代での実績に基づくと、貯銑炉に保持した溶銑がＳｉ＝０．３０質量％以上ではスラグの増量が観察されているため、Ｓｉ＝０．０５〜０．３０質量％の範囲で操業することが望ましい。また、０．７〜０．１５質量％で調整すれば、一層好ましい。下限を０．０５質量％としたのは、それ未満では、Ｓｉの添加効果が出現しないからである。
本発明では、Ｓｉ源である合金鉄の種類は特に限定しないが、ＦｅＳｉやＳｉＭｎ等の珪素合金、Ｓｉを１．０〜１０．０質量％含有する高ＳｉのＦｅＣｒの使用で良い。高ＳｉのＦｅＣｒは、比較的安価であり、含Ｃｒ溶銑の貯銑炉においては、Ｓｉ源及びＣｒ源としても有効だからである。
It should be noted that, based on the results of the first furnace cost described above, an increase in slag has been observed when the hot metal held in the storage furnace is Si = 0.30 mass% or more, so Si = 0.05-0. It is desirable to operate in the range of 30% by mass. Moreover, if it adjusts by 0.7-0.15 mass%, it is still more preferable. The reason why the lower limit is set to 0.05% by mass is that if it is less than that, the effect of adding Si does not appear.
In the present invention, the type of the alloy iron as the Si source is not particularly limited, but may be a silicon alloy such as FeSi or SiMn, or high Si FeCr containing 1.0 to 10.0% by mass of Si. This is because high-Si FeCr is relatively inexpensive and is also effective as a Si source and a Cr source in a Cr-containing hot metal storage furnace.
また、本発明では、加熱装置の種類も特に限定するものでなく、気体あるいは液体を燃料としたバーナーや誘導加熱やプラズマ加熱等の電気による加熱方法が利用できる。ただし、今までの実績では、作業性や経済的な理由で誘導加熱装置の利用が好ましい。 In the present invention, the type of the heating device is not particularly limited, and an electric heating method such as a burner using gas or liquid as fuel and induction heating or plasma heating can be used. However, in the past results, it is preferable to use an induction heating device for workability and economical reasons.
ステンレス鋼の溶製工場に設けた誘導加熱装置付き貯銑炉に、Ｃｒ鉱石を炭材で溶融還元して溶製した含Ｃｒ溶鉄を保持し、脱炭精錬炉へ払い出し待機中に、本発明に係る方法を適用し、該含Ｃｒ溶鉄を覆うスラグの流動性調整を行った。その誘導加熱装置付き貯銑炉は、図５に示した構造とほぼ類似したもので、容量１４００ｔで誘導加熱装置は２．０ＭＷ×４基の能力である。 In a storage furnace equipped with an induction heating device in a stainless steel smelting factory, Cr-containing molten iron obtained by melting and reducing Cr ore with a carbonaceous material is held, and it is waiting for delivery to a decarburization refining furnace. The method concerning this was applied, and the fluidity | liquidity adjustment of the slag which covers this Cr containing molten iron was performed. The storage furnace with the induction heating device is substantially similar to the structure shown in FIG. 5, and has a capacity of 1400 t and the induction heating device has a capacity of 2.0 MW × 4 units.
まず、貯銑炉内スラグの固化及び増量の傾向が見られる毎に、Ｓｉ＝１〜４質量％を含むＦｅＣｒ合金を炉内へ投入した。この時のＳｉ量は、１ｋｇ／溶銑−ｔ程度であった。 First, whenever a tendency of solidification and increase in the amount of slag in the storage furnace was observed, an FeCr alloy containing Si = 1 to 4% by mass was introduced into the furnace. The amount of Si at this time was about 1 kg / molten iron-t.
その結果、図３に示すように、炉内スラグ中のＴ．Ｆｅ（Ｔはｔｏｔａｌの意味）が従来は平均で２０質量％であったものが、本発明の適用により平均で５質量％以下に低下した。 つまり、スラグ中のＦｅ酸化物及び投入したＳｉで還元され、Ｆｅが溶鉄へ移行したのである（なお、図３は、横軸の尺度に溶鉄中のＳｉ濃度を採用）。これによって、溶鉄の脱炭精錬炉への払い出し時に同時に行うスラグの排出は、流動性が改善されたため、円滑に実施できた。図４に示すように、１回の溶鉄払い出し当たりに排出されるスラグ量は、従来は平均で０．５ｔしかなかったのが、平均で０．８ｔにまで増加したのである。これによって、今までは、定常的に３０〜６０ｋｇ／溶銑−ｔ程度存在していたスラグが、２９質量％も低減した。耐火物の溶損に関しては、図１に示すように、本発明の適用により、従来の損耗速度の約３０％に低減できた。また、貯銑炉で実施するスクラップの溶解についても改善があり、図２に示すように、本発明の実施前に比べ、溶解速度が１８％も向上した。参考のために、従来と本発明の適用後での代表的なスラグの成分を表１に示しておく。 As a result, as shown in FIG. Although Fe (T means total) is 20% by mass on average in the past, it has decreased to 5% by mass or less on average by applying the present invention. In other words, the Fe oxide in the slag and the introduced Si were reduced, and Fe moved to the molten iron (FIG. 3 adopts the Si concentration in the molten iron as a scale on the horizontal axis). As a result, the discharge of slag simultaneously with the discharge of molten iron to the decarburization refining furnace was smoothly performed because the fluidity was improved. As shown in FIG. 4, the amount of slag discharged per molten iron dispense is increased from 0.5t on average to 0.8t on average. As a result, the amount of slag that has been in the steady range of about 30 to 60 kg / molten iron-t until now has been reduced by 29% by mass. As shown in FIG. 1, the refractory melting loss was reduced to about 30% of the conventional wear rate by applying the present invention. Moreover, there was also an improvement in the melting of scrap carried out in the storage furnace, and as shown in FIG. 2, the melting rate was improved by 18% compared to before the practice of the present invention. For reference, the typical slag components after application of the present invention and the present invention are shown in Table 1.
なお、図１の耐火物損耗指数は、本発明を適用する前の耐火物損耗速度（ｍｍ／ｄａｙ）を１．０とした時の相対値、及び図２の溶解速度指数は、本発明を適用する前の溶解速度（ｔｏｎ／ｈｒ）を１．０とした時の相対値である。また、Ｓｉを１．０〜１０．０質量％含有する高Ｓｉのフェロクロムは、比較的安価であるが、転炉での使用は造滓材使用量の増加を招くため難しいが、含Ｃｒ溶銑保持炉においてはＳｉ源、Ｃｒ源として比較的有効に利用できることもわかった。 The refractory wear index in FIG. 1 is the relative value when the refractory wear rate (mm / day) before applying the present invention is 1.0, and the dissolution rate index in FIG. It is a relative value when the dissolution rate (ton / hr) before application is 1.0. Further, high Si ferrochrome containing 1.0 to 10.0% by mass of Si is relatively inexpensive, but its use in a converter is difficult because it causes an increase in the amount of ironmaking material used. It was also found that the holding furnace can be used relatively effectively as a Si source and a Cr source.
このように、本発明によれば、貯銑炉においてＳｉを含有する合金鉄を投入することで、スラグ中のＦｅ、Ｃｒを還元回収し、その結果、スラグの流動性が改善され、貯銑炉から溶銑を出鋼する際に同時に排出されるスラグ量が増加したのである。また、スラグ排出量の増加によって、貯銑炉内のスラグ量が低減するため、スラグと貯銑炉の内張り耐火物の接触面積が減少し、スラグの耐火物への浸透することによる耐火物の劣化と、それに伴う耐火物の割れの発生が抑止する。また、スラグが耐火物を侵食する面積が減少するため、耐火物の損耗も抑制される。さらに、スラグ量が削減できるので、加熱装置付き貯銑炉へのスクラップの投入時に、該スクラップへのスラグの付着が起きず、さらに加えて、溶鉄のスクラップへの侵炭が良好に進行するので、スクラップの溶解速度も向上した。 As described above, according to the present invention, Fe and Cr in the slag are reduced and recovered by introducing the alloy iron containing Si in the storage furnace. As a result, the fluidity of the slag is improved, and the storage The amount of slag discharged at the same time that the hot metal was discharged from the furnace increased. In addition, since the amount of slag in the storage furnace is reduced due to the increase in slag discharge, the contact area between the slag and the refractory lining the storage furnace is reduced, and the refractory due to penetration of slag into the refractory is reduced. Deterioration and accompanying cracking of the refractory are suppressed. Further, since the area where the slag erodes the refractory is reduced, the wear of the refractory is also suppressed. Furthermore, since the amount of slag can be reduced, when scrap is put into a storage furnace equipped with a heating device, no slag adheres to the scrap, and in addition, carburization of molten iron to the scrap proceeds well. Also, the dissolution rate of scrap was improved.
上記実施例は含クロム溶鉄の場合であるが、本発明は、それに限るものではなく、通常
の製鋼に用いる溶銑予備処理された高炉溶銑にも適用できることは、説明するまでもない。
Although the said Example is a case of chromium containing molten iron, it cannot be overemphasized that this invention is applicable to the blast furnace hot metal by which the hot metal pretreatment used for normal steel manufacture is not restricted to it.
１ 貯銑炉
２ 溶鉄（又は溶銑）
３ 加熱装置（誘導式）
４ 装入口
５ サンプリング孔
６ 出鉄口又はスラグ排出口
７ 内張り耐火物
1
3 Heating device (induction type)
4
Claims (5)
炉内に残留するスラグにＳｉを含有する合金鉄を投入し、該スラグ中に含まれる低級酸化物の濃度を低下して、炉からのスラグの排出性を高めることを特徴とする貯銑炉内スラグの流動性調整方法。 When adding and scraping iron scrap to molten iron held in a storage furnace equipped with a heating means to increase the amount of molten iron retained,
A storage furnace characterized in that Si-containing alloy iron is introduced into the slag remaining in the furnace, the concentration of lower oxides contained in the slag is lowered, and the slag discharge from the furnace is increased. How to adjust the fluidity of the inner slag.
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