JP2013133536A - Method for producing molten steel - Google Patents
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Abstract
Description
本発明は、溶鋼の製造方法に関する。 The present invention relates to a method for producing molten steel.
転炉に装入する溶銑は、高炉から出銑した溶銑に対して脱りん処理、脱珪処理、及び脱硫処理を行った予備処理銑と、これらの処理を行っていない普通銑との２種類に分けられる。
脱りん処理工程では酸素源を含んだ脱りん剤が溶銑に添加され、脱りん処理後の溶銑のＰ濃度は、通常は０．０２０〜０．０８０質量％となるが、脱りん剤の冷却効果によって溶銑の温度は低下する。この時、溶銑中のＳｉも酸化除去されて、Ｓｉ濃度は０．０５質量％以下（通常は０．０２質量％未満）にまで低下する。一方、普通銑のＰ濃度は０．１００〜０．１６０質量％であり、Ｓｉ濃度も０．１０〜０．７０質量％である。また、普通銑は、溶銑温度についても脱りん処理銑より高く、転炉での吹錬によって発熱するＳｉを多く含むことから、熱的余裕を多く有する。
There are two types of hot metal to be charged into the converter: a pre-treated iron that has been subjected to dephosphorization, desiliconization, and desulfurization treatment of the molten iron discharged from the blast furnace, and ordinary iron that has not been subjected to these treatments. It is divided into.
In the dephosphorization process, a dephosphorizing agent containing an oxygen source is added to the hot metal, and the P concentration of the hot metal after the dephosphorizing process is usually 0.020 to 0.080% by mass. Depending on the effect, the temperature of the hot metal decreases. At this time, Si in the hot metal is also oxidized and removed, and the Si concentration is reduced to 0.05% by mass or less (usually less than 0.02% by mass). On the other hand, the P concentration of ordinary soot is 0.100 to 0.160 mass%, and the Si concentration is also 0.10 to 0.70 mass%. Further, the normal hot metal has a hot metal temperature higher than that of the dephosphorized steel, and contains a lot of Si that generates heat by blowing in the converter, and therefore has a large thermal margin.
製品の要求から溶銑のＰ濃度を低減させたい場合に上記の脱りん処理を行うと、溶銑の温度が低下しＰ濃度が低下するとともに、Ｓｉ濃度も低下する。転炉での精錬においては、Ｓｉの酸化により発熱するので、Ｓｉ濃度の低下は精錬工程における熱量の不足をもたらし、結果として炭素質物質、フェロシリコン等の昇熱剤が必要となる。近年、製鉄におけるエネルギー消費の低減が求められているため、低Ｐ濃度であり且つ高Ｓｉ濃度の溶銑を得ることが好ましいが、前述の通り通常の脱りん処理を行うと、Ｓｉ濃度が不可避的に低下してしまうという問題があった。 If it is desired to reduce the P concentration of the hot metal from the requirement of the product, if the above dephosphorization treatment is performed, the temperature of the hot metal is lowered, the P concentration is lowered, and the Si concentration is also lowered. In refining in a converter, heat is generated due to oxidation of Si. Therefore, a decrease in the Si concentration results in a shortage of heat in the refining process, and as a result, a heating agent such as a carbonaceous material or ferrosilicon is required. In recent years, there has been a demand for reduction in energy consumption in iron making, so it is preferable to obtain hot metal having a low P concentration and a high Si concentration. However, as described above, when ordinary dephosphorization treatment is performed, the Si concentration is unavoidable. There was a problem that it would drop.
溶銑の成分、特にＰ濃度とＳｉ濃度を調整する方法としては、例えば特許文献１に、混銑車で脱りん処理を行い、その際に余った脱りん処理銑を普通銑と混合してＰ濃度を０．０６０〜０．０９０質量％に調整し、転炉に装入する方法が記載されている。また、特許文献２には、Ｓｉ濃度とＰ濃度が調整された溶銑を転炉型の精錬容器に装入して脱りん処理を行う溶銑予備処理方法が記載されている。ただし、特許文献２には、溶銑のＳｉ濃度とＰ濃度を調整する具体的な方法は記載されていない。さらに、特許文献３には、脱りん処理を行った溶鋼と脱りん処理を行っていない溶銑（すなわち普通銑）とを混合して、Ｓｉ濃度が０．２１質量％、Ｐ濃度が０．０２３質量％、Ｃ濃度が０．７０質量％の溶鋼を調製する方法が開示されている。
As a method for adjusting the hot metal components, in particular, the P concentration and the Si concentration, for example,
従来においては、低いＰ濃度が要求される鋼種に対して、脱りん処理銑を用いていたため、溶銑のＳｉ濃度も通常０．０２質量％未満まで低下していた。それゆえ、転炉での吹錬ではＳｉの燃焼による発熱が期待できないため、著しい熱量不足になりやすく、昇熱剤を添加する必要があった。昇熱剤としては、炭素質物質（例えばコークス、土状黒鉛、無煙炭）、フェロシリコン（ＦｅＳｉ）、ＳｉＣ、シリコンスラッジ等があげられる。 Conventionally, since a dephosphorizing iron was used for a steel type that requires a low P concentration, the Si concentration of the hot metal was usually reduced to less than 0.02% by mass. Therefore, since heat generation due to the combustion of Si cannot be expected in the blowing in the converter, a significant amount of heat tends to be short, and it is necessary to add a heating agent. Examples of the heat raising agent include carbonaceous materials (for example, coke, earthy graphite, anthracite), ferrosilicon (FeSi), SiC, silicon sludge and the like.
コークスや土状黒鉛、無煙炭を使用した場合は、不純物として含まれるＳが溶鋼中に混入して成分スペックを外れる懸念があるとともに、溶銑に吹込む酸素量が多くなるため吹錬時間が延長し、転炉生産性を低下させてしまうおそれがある。また、フェロシリコン（ＦｅＳｉ）やＳｉＣ、シリコンスラッジを使用した場合は、ＳｉＯ2 が多く生成することで適正な吹錬塩基度（ＣａＯ／ＳｉＯ2 比を指し、適正値は２．５〜５．０である）を保てなくなり、ＣａＯの添加量が増大するという問題がある。 When coke, earthy graphite, or anthracite is used, there is a concern that S contained as an impurity may enter the molten steel and deviate from the component specifications, and the amount of oxygen blown into the hot metal will increase, so the blowing time will be extended. The converter productivity may be reduced. In addition, when ferrosilicon (FeSi), SiC, or silicon sludge is used, a large amount of SiO 2 is generated, indicating an appropriate blowing basicity (CaO / SiO 2 ratio, and an appropriate value is 2.5 to 5. There is a problem that the amount of CaO added increases.
さらに、近年においては、ＣＯ2 排出抑制を目的として、転炉吹錬での溶銑配合率（転炉に装入する主原料（溶銑とスクラップ）に占める溶銑の割合）の低減がなされているが、スクラップを大量に配合する転炉操業では熱量不足になりやすく、この場合でも昇熱剤を多く使用する必要がある。
これらの問題を回避するためには、溶銑のＳｉ濃度を高めて昇熱剤の使用量を削減することが好ましい。しかしながら、Ｓｉ濃度の向上による定量的な昇熱剤使用量低減効果、及び、Ｓｉ濃度の上昇に伴って増加が懸念される転炉吹錬初期のスロッピング（転炉内容物の噴出し現象）の程度が知られておらず、どのようなＳｉ濃度の溶銑を調製すべきかは明確ではなかった。
Furthermore, in recent years, for the purpose of suppressing CO 2 emissions, the hot metal blending ratio (ratio of hot metal occupying the main raw materials (hot metal and scrap) charged in the converter) has been reduced for the purpose of suppressing the CO 2 emission. In the converter operation in which a large amount of scrap is blended, the amount of heat tends to be insufficient, and even in this case, it is necessary to use a large amount of a heat raising agent.
In order to avoid these problems, it is preferable to increase the Si concentration of the hot metal to reduce the amount of heat-up agent used. However, quantitative heat-reducing agent usage reduction effect by improving Si concentration, and slopping in the initial stage of converter blowing where there is a concern about increase with increasing Si concentration (blowing phenomenon of converter contents) It was not clear what Si concentration of hot metal should be prepared.
例えば、特許文献１〜３に記載されたＳｉ濃度とＰ濃度の調整方法は、いずれも転炉精錬における昇熱剤の低減を目的としたものではなく、Ｓｉ濃度の向上による昇熱剤使用量低減効果やＳｉ濃度の上昇によるスロッピングの問題についての認識もない。特許文献１に開示の技術は、Ｐ濃度０．０３０質量％以下の低炭素鋼の製造が目的である。また、特許文献２に開示の技術は、スラグの溶融性を改善するためのものであって、Ｐ濃度が高いほどＳｉ濃度も高くなるように設定されるものである。さらに、特許文献３に開示の技術は、低Ｐ濃度且つ低Ｓ濃度の鋼を製造するための方法である。
そこで、本発明は、上記のような従来技術が有する問題点を解決し、低Ｐ濃度の溶鋼を製造する場合でも、転炉での吹錬における昇熱剤の使用量を少量とすることができる溶鋼の製造方法を提供することを課題とする。
For example, the methods for adjusting the Si concentration and the P concentration described in
Therefore, the present invention solves the problems of the prior art as described above, and even when producing molten steel with a low P concentration, it is possible to reduce the amount of the heating agent used in the blowing in the converter. It is an object of the present invention to provide a method for producing molten steel.
前記課題を解決するため、本発明の態様は次のような構成からなる。すなわち、本発明の一態様に係る溶鋼の製造方法は、脱りん処理した溶銑と脱りん処理していない溶銑とを、溶銑中のＳｉ濃度が０．１０質量％以上０．５０質量％以下となるように混合し、この混合した溶銑を転炉で吹錬することを特徴とする。
このような溶鋼の製造方法においては、前記混合した溶銑中のＰ濃度を０．０３０質量％以上０．１００質量％以下とすることが好ましい。また、前記脱りん処理した溶銑中のＰ濃度を０．０３質量％以上とし、Ｓｉ濃度を０．０５質量％以下とすることが好ましい。
In order to solve the above problems, an aspect of the present invention has the following configuration. That is, in the method for manufacturing molten steel according to one aspect of the present invention, the dephosphorized hot metal and the non-dephosphorized hot metal have a Si concentration in the hot metal of 0.10% by mass to 0.50% by mass. It mixes so that it may become, and this mixed hot metal is blown in a converter.
In such a molten steel manufacturing method, it is preferable that the P concentration in the mixed hot metal is 0.030 mass% or more and 0.100 mass% or less. Moreover, it is preferable that the P concentration in the dephosphorized hot metal is 0.03 mass% or more and the Si concentration is 0.05 mass% or less.
さらに、昇熱剤としてフェロシリコンのみを用いて前記混合した溶銑を前記転炉で吹錬し、前記フェロシリコンの使用量を、Ｓｉの量が前記混合した溶銑１トン当たり３．７５ｋｇ以下となるような量とすることができる。また、昇熱剤としてフェロシリコン及び炭素質物質のみを用いて前記混合した溶銑を前記転炉で吹錬し、前記フェロシリコンの使用量を、Ｓｉの量が前記混合した溶銑１トン当たり３．７５ｋｇ以下となるような量とし、前記炭素質物質の使用量を前記混合した溶銑１トン当たり１０．０ｋｇ以下とすることができる。 Further, the mixed hot metal using only ferrosilicon as a heat-up agent is blown in the converter, and the amount of the ferrosilicon used is 3.75 kg or less per ton of the mixed hot metal. Such an amount can be used. Also, the mixed hot metal using only ferrosilicon and a carbonaceous material as a heat-up agent is blown in the converter, and the amount of the ferrosilicon used is 3 per 1 ton of hot metal mixed with the amount of Si. The amount can be 75 kg or less, and the amount of the carbonaceous material used can be 10.0 kg or less per 1 ton of the mixed hot metal.
さらに、前記転炉での吹錬において使用する昇熱剤の実効発熱量を求め、全昇熱剤の実効発熱量の合計が前記混合した溶銑１トン当たり３００００ｋｃａｌ以下となるような量の昇熱剤を前記転炉での吹錬で使用することができる。さらに、前記転炉での吹錬における溶銑配合率を９０質量％以下とすることができる。 Further, the effective heat generation amount of the heat raising agent used in the blowing in the converter is determined, and the amount of heat increase is such that the total effective heat generation amount of all the heat raising agents is 30000 kcal or less per 1 ton of the mixed hot metal. The agent can be used for blowing in the converter. Furthermore, the hot metal compounding ratio in the blowing in the converter can be 90% by mass or less.
本発明に係る溶鋼の製造方法は、Ｓｉ濃度を０．１０質量％以上０．５０質量％以下とした溶銑を転炉で吹錬するので、低Ｐ濃度の溶鋼を製造する場合でも昇熱剤の使用量を少量とすることができる。 In the method for producing molten steel according to the present invention, the hot metal having a Si concentration of 0.10 mass% or more and 0.50 mass% or less is blown in a converter, so that even when producing low P concentration molten steel, Can be used in a small amount.
本発明に係る溶鋼の製造方法の実施の形態を、図面を参照しながら詳細に説明する。図１は、本発明の一実施形態である溶鋼の製造方法を説明する概略工程図である。
高炉から出銑した溶銑を転炉で吹錬する際に使用する昇熱剤の量を低減するためには、吹錬での発熱反応に寄与するＳｉを溶銑中に存在させる必要がある。すなわち、転炉に装入する溶銑は、低Ｐ濃度で且つ高Ｓｉ濃度であることが好ましい。しかしながら、高炉で製造された溶銑に通常の脱りん処理を行う従来法では、ＰとともにＳｉも除去されるため、溶銑中のＳｉ濃度は０．０２質量％未満となり（図４を参照）、低Ｐ濃度且つ高Ｓｉ濃度の溶銑は得られない。
An embodiment of a method for producing molten steel according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic process diagram illustrating a method for producing molten steel according to an embodiment of the present invention.
In order to reduce the amount of the heating agent used when the hot metal discharged from the blast furnace is blown in the converter, it is necessary that Si contributing to the exothermic reaction in the blowing be present in the hot metal. That is, it is preferable that the hot metal charged in the converter has a low P concentration and a high Si concentration. However, in the conventional method of performing normal dephosphorization treatment on hot metal produced in a blast furnace, Si is also removed together with P, so the Si concentration in the hot metal is less than 0.02% by mass (see FIG. 4), and low Hot metal having a P concentration and a high Si concentration cannot be obtained.
そこで、本実施形態においては、製造する鋼種に応じて定められているＰ濃度を満たしつつＳｉを残すため、転炉に装入して吹錬する溶銑として、高炉から出銑した溶銑に対して脱りん処理を行った脱りん処理銑（Ｓｉ濃度は０．０２質量％未満）と、脱りん処理を行っていない普通銑（Ｓｉ濃度は０．１０質量％以上０．７０質量％以下）とを混合して得られた混合銑（Ｓｉ濃度は０．１０質量％以上０．５０質量％以下）を用いた（図１を参照）。 Therefore, in the present embodiment, in order to leave Si while satisfying the P concentration determined according to the steel type to be manufactured, the hot metal discharged from the blast furnace is used as the hot metal charged in the converter and blown. Dephosphorized soot (Si concentration is less than 0.02% by mass) subjected to dephosphorization treatment and normal soot (Si concentration is not less than 0.10% by mass to 0.70% by mass) not subjected to dephosphorization treatment A mixed soot obtained by mixing (Si concentration is 0.10 mass% or more and 0.50 mass% or less) was used (see FIG. 1).
すなわち、２種の溶銑を混合することによって、低Ｐ濃度が要求される鋼種において昇熱剤の低減に好適なＳｉ濃度を有する溶銑（混合銑）を製造し、この溶銑を用いて昇熱剤の使用量が少ない条件で転炉で吹錬を行って溶鋼を製造する。
本実施形態の溶鋼の製造方法によれば、転炉での吹錬に使用できるＰ濃度の範囲内でＳｉ濃度を高くすることができるので、昇熱剤コストを１０〜５０％削減することが可能である（図３のグラフを参照）。また、脱りん処理銑を単独使用する従来法と比較して熱的な余裕が生まれるため、転炉吹錬でのさらなる溶銑配合率の低減が可能である。特に、脱りん処理銑を必要とし且つ出鋼温度が高い低Ｐ濃度の高合金鋼種では、一般に昇熱剤を多量に使用しているので、本実施形態の溶鋼の製造方法を適用すれば、脱りん処理銑の熱不足を補って、昇熱剤コストを大幅に削減することができる。
That is, by mixing two types of hot metal, a hot metal (mixed iron) having a Si concentration suitable for reducing the heat-generating agent is produced in a steel type that requires a low P concentration, and using this hot metal, the heat-generating agent is produced. The molten steel is manufactured by blowing in a converter under the condition that the amount of use is small.
According to the molten steel manufacturing method of the present embodiment, the Si concentration can be increased within the range of the P concentration that can be used for blowing in the converter, so that the heat raising agent cost can be reduced by 10 to 50%. It is possible (see graph in FIG. 3). In addition, since a thermal margin is generated as compared with the conventional method using a dephosphorized slag alone, it is possible to further reduce the hot metal content in the converter blowing. In particular, in a low P concentration high alloy steel that requires dephosphorization and high steel output temperature, a large amount of a heat increasing agent is generally used. Therefore, if the method for producing molten steel of this embodiment is applied, Compensating for the lack of heat in the dephosphorized soot, it is possible to significantly reduce the cost of the heat-up agent.
脱りん処理銑と普通銑との混合比率によって様々なＳｉ濃度とＰ濃度の組合せが可能であるが、混合銑のＳｉ濃度が高すぎると適正な吹錬塩基度を維持できなくなるとともに、転炉吹錬時に噴出し現象（スロッピング）が生じる懸念がある。本発明者らは、吹錬初期のスロッピングによる転炉の操業への影響を抑えるためには、転炉に装入して吹錬する溶銑のＳｉ濃度を０．５０質量％以下とする必要があることを見出した。 Various combinations of Si concentration and P concentration are possible depending on the mixing ratio of dephosphorized soot and ordinary soot, but if the Si concentration in the mixed soot is too high, it will not be possible to maintain proper blowing basicity, and the converter There is a concern that a blowing phenomenon (sloping) may occur during blowing. In order to suppress the influence on the operation of the converter due to the slopping in the initial stage of blowing, the present inventors need to set the Si concentration of the hot metal to be charged into the converter and blown to 0.50% by mass or less. Found that there is.
すなわち、図２のグラフに示すように、溶銑のＳｉ濃度が０．４０質量％超過０．５０質量％以下の場合は、スロッピング発生率が１０．１％で、転炉の操業への影響が小さいのに対して、溶銑のＳｉ濃度が０．５０質量％超過０．６０質量％以下の場合は、スロッピング発生率が２８．２％となり、転炉の操業への影響が大きい。よって、溶銑のＳｉ濃度は０．５０質量％以下とする必要がある。 That is, as shown in the graph of FIG. 2, when the Si concentration in the hot metal exceeds 0.40% by mass and is 0.50% by mass or less, the slopping rate is 10.1%, which affects the operation of the converter. On the other hand, when the Si concentration in the hot metal is more than 0.50% by mass and not more than 0.60% by mass, the slopping rate is 28.2%, which greatly affects the operation of the converter. Therefore, the Si concentration of the hot metal needs to be 0.50% by mass or less.
一方、溶銑のＳｉ濃度が低すぎると、昇熱剤の使用量の低減への寄与が小さくなる。図３のグラフに示すように、溶銑のＳｉ濃度が高くなるに従って転炉での吹錬における昇熱剤の使用量を削減することができるので、昇熱剤コストが低減される。図３のグラフから分かるように、従来法の吹錬に対して昇熱剤コストを１０％以上削減するためには、転炉に装入して吹錬する溶銑のＳｉ濃度を０．１０質量％以上とする必要がある。 On the other hand, if the Si concentration in the hot metal is too low, the contribution to the reduction in the amount of heat-up agent used will be small. As shown in the graph of FIG. 3, as the Si concentration of the hot metal becomes higher, the amount of the heat raising agent used in the blowing in the converter can be reduced, so that the heat raising agent cost is reduced. As can be seen from the graph in FIG. 3, in order to reduce the heating agent cost by 10% or more compared to the conventional blowing, the Si concentration of the molten iron charged in the converter and blown is 0.10 mass. % Or more is necessary.
本実施形態においては、例えば高炉鍋又は混銑車（トピードカー）から装入鍋に払い出す工程において、混合銑中のＳｉ濃度が０．１０質量％以上０．５０質量％以下となり且つＰ濃度が製造する鋼種に応じた目標値となるように、混合比率を調整しつつ脱りん処理銑と普通銑とを混合して、転炉に装入する溶銑を得る。２種の溶銑の混合は、脱りん処理銑を保持する容器と普通銑を保持する容器とのそれぞれから所定量を量り取って、装入鍋に受け入れるようにすればよい。 In the present embodiment, for example, in the step of discharging from a blast furnace pan or a kneading car (topped car) to the charging pan, the Si concentration in the mixing pan becomes 0.10% by mass to 0.50% by mass and the P concentration is manufactured. The dephosphorization treatment iron and the normal iron are mixed while adjusting the mixing ratio so as to obtain a target value corresponding to the steel type to be obtained, thereby obtaining the hot metal to be charged into the converter. The mixing of the two types of hot metal may be carried out by weighing out a predetermined amount from each of the container holding the dephosphorization-treated bar and the container holding the normal barb and receiving it in the charging pan.
このようにＰ濃度が許容される上限以下であり且つＳｉ濃度の高い溶銑を転炉に装入することにより、転炉での吹錬における昇熱剤の使用量の削減が可能である。昇熱剤の種類は特に限定されるものではなく、金属の酸化熱を利用した昇熱剤や、炭素のＣＯまでの酸化熱を利用した昇熱剤を好適に使用することができる。 In this way, by using molten iron having a P concentration that is less than or equal to the allowable upper limit and a high Si concentration in the converter, it is possible to reduce the amount of the heating agent used in blowing in the converter. The type of the heat-up agent is not particularly limited, and a heat-up agent using metal oxidation heat or a heat-up agent using heat of oxidation up to carbon CO can be suitably used.
高Ｓｉ濃度の溶銑を用いた場合に、実際にどの程度の量の昇熱剤で転炉の操業が可能かは、それぞれの昇熱剤の発熱量に支配される。ただし、転炉に装入した昇熱剤の発熱量の全てが昇熱に用いられるわけではない。例えば、粉状の昇熱剤の場合は、その一部が集塵装置によって吸引されて、溶銑に到達する歩留りが下がってしまう。また、昇熱剤の酸化によって発生した熱も、その全てが有効に昇熱に寄与するわけではない。すなわち、それぞれの昇熱剤について、実効発熱量を求めて、昇熱剤の使用量を決定する必要がある。実効発熱量は、定性的には次のように理解できる。
実効発熱量（ｋｃａｌ／昇熱剤ｋｇ）＝昇熱剤から理論的に得られる発熱量（ｋｃａｌ／昇熱剤ｋｇ）×着熱効率（−）
When a hot metal having a high Si concentration is used, the actual amount of the heating agent that can be operated with the heating agent is governed by the heating value of each heating agent. However, not all of the calorific value of the heating agent charged in the converter is used for heating. For example, in the case of a powdery heat-up agent, a part of the heat-up agent is sucked by the dust collector, and the yield reaching the hot metal is lowered. Further, not all of the heat generated by the oxidation of the heat raising agent contributes effectively to the heat rising. That is, it is necessary to determine the effective amount of heat generated for each heat increasing agent and to determine the amount of heat increasing agent used. The effective calorific value can be qualitatively understood as follows.
Effective calorific value (kcal / kg of heat-raising agent) = calorific value theoretically obtained from the heat-heating agent (kcal / kg of heat-heating agent) x heat receiving efficiency (-)
ここで、昇熱剤から理論的に得られる発熱量（ｋｃａｌ／昇熱剤ｋｇ）は、昇熱剤中の酸化発熱に利用される物質の比率（−）と、それぞれの物質の酸化によって得られる理論発熱量（ｋｃａｌ／ｋｇ）との積となる。なお、着熱効率とは、昇熱剤から発生した熱のうちどの程度の熱が実際に利用されるかの比率を示す。
ここで、昇熱剤中の酸化発熱に利用される物質の比率は、昇熱剤の純度や組成に影響される。それぞれの物質の酸化によって得られる理論発熱量は、熱力学的計算によって求めることができる。この時、金属類は安定酸化物までの酸化熱、ＣはＣＯまでの酸化熱を計算する。着熱効率には、添加歩留りや熱ロスが影響する。
Here, the calorific value (kcal / kg of the heat raising agent) theoretically obtained from the heat raising agent is obtained by the ratio (−) of the substance used for the oxidation heat generation in the heat raising agent and the oxidation of each substance. Product of the theoretical calorific value (kcal / kg). The heat receiving efficiency indicates a ratio of how much heat is actually used out of the heat generated from the heat increasing agent.
Here, the ratio of the substance used for the oxidation heat generation in the heat increasing agent is influenced by the purity and composition of the heat increasing agent. The theoretical calorific value obtained by oxidation of each substance can be determined by thermodynamic calculation. At this time, metals calculate the heat of oxidation up to the stable oxide, and C calculates the heat of oxidation up to CO. The yield of heat and heat loss affect the heat receiving efficiency.
しかし、このうち着熱効率は理論的に求めることは容易ではない。そこで、本発明者らは、昇熱剤の使用量を種々変化させて実際に転炉の操業を行い、その時の熱バランスを測定することによって、昇熱剤から理論的に得られる熱量のうちどの程度の割合の熱が昇熱に寄与したかを求め、それぞれの昇熱剤について実効発熱量を実験的に求めた。具体的には、昇熱剤の使用量と、昇熱に寄与した熱量とのプロットをとり、その傾きを求め、それを実効発熱量とした。単純には、同じ溶銑を用いて同じ条件で吹錬を行い、昇熱剤を使用した場合と、使用しなかった場合との溶鋼の温度の差から、実効発熱量を推定することができる。種々の昇熱剤について求めた実効発熱量の値を、表１に示す。 However, it is not easy to theoretically determine the heat receiving efficiency. Therefore, the present inventors actually changed the amount of use of the heat-up agent, actually operated the converter, and measured the heat balance at that time, so that of the amount of heat theoretically obtained from the heat-up agent. The degree of heat that contributed to the heat increase was determined, and the effective heat generation amount was experimentally determined for each heat increasing agent. Specifically, a plot of the amount of heat-elevating agent used and the amount of heat that contributed to the temperature increase was taken, the slope was determined, and this was used as the effective heat value. Simply, the effective heating value can be estimated from the difference in the temperature of the molten steel between the case where the heating agent is used and the case where the heating agent is not used. Table 1 shows the values of the effective heat generation values obtained for various heat raising agents.
この実効発熱量を用いれば、種々の昇熱剤を単独で又は２種以上を混合して使用した場合に、どの程度の昇熱剤の使用量で転炉の操業が行えるかの指針が得られる。本発明者らが後述する実施例に示す操業を解析した結果、本実施形態の方法による高Ｓｉ濃度且つ低Ｐ濃度の溶銑を転炉で吹錬する場合には、使用した全種の昇熱剤の全実効発熱量の合計として、溶銑１トン当たり３００００ｋｃａｌ以下の昇熱剤を使用することで、転炉の操業が可能であることが明らかとなった。 By using this effective heat value, a guideline can be obtained as to how much heating agent can be used when various heating agents are used alone or in admixture of two or more. It is done. As a result of analyzing the operations shown in Examples described later by the present inventors, when hot metal having a high Si concentration and a low P concentration by the method of this embodiment is blown in a converter, all types of used heat increases It became clear that the operation of the converter was possible by using a heating agent of 30000 kcal or less per ton of hot metal as the total of the total effective heating value of the agent.
なお、転炉での吹錬時の溶銑配合率、すなわち転炉に装入する原料に占める溶銑の比率は、溶銑の質量／（溶銑の質量＋スクラップの質量）×１００で算出される数値であって、この数値が９０質量％以下の場合は、昇熱剤の必要量が多くなるため、本実施形態の方法の適用がより効果的となる。 The ratio of hot metal at the time of blowing in the converter, that is, the ratio of hot metal to the raw material charged in the converter, is a numerical value calculated by the mass of hot metal / (mass of hot metal + mass of scrap) × 100. And when this figure is 90 mass% or less, since the required amount of a heat-transfer agent increases, application of the method of this embodiment becomes more effective.
〔実施例〕
以下に、実施例及び比較例を示して、本発明をさらに具体的に説明する。脱りん処理銑と普通銑（未脱りん処理銑）とを装入鍋で混合し、種々の混合銑を得た。そして、混合銑及びスクラップを転炉に装入し、昇熱剤を添加して、吹錬を行った。比較例の場合は、混合銑の代わりに脱りん処理銑のみを吹錬に用いた。
〔Example〕
Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. The dephosphorized cocoon and the ordinary cocoon (non-dephosphorized cocoon) were mixed in a charging pan to obtain various mixed cocoons. Then, the mixed soot and scrap were charged into a converter, and a heating agent was added to perform blowing. In the case of the comparative example, only the dephosphorized soot was used for blowing instead of the mixed soot.
表２に、使用した脱りん処理銑（表２には「脱りん銑」と記してある）及び普通銑中のＳｉ濃度及びＰ濃度、脱りん処理銑の混合率（混合銑中の脱りん処理銑の比率）、混合銑中のＳｉ濃度及びＰ濃度、混合銑の吹錬時の溶銑配合率、混合銑の吹錬時の混合銑１トン当たりの昇熱剤の使用量、並びに、使用した全昇熱剤の実効発熱量の合計値（混合銑１トン当たりの数値）を示す。なお、吹錬終了後の出鋼温度は１６７０〜１６８０℃である。また、昇熱剤として使用した炭素質物質は土状黒鉛である。さらに、昇熱剤として使用したフェロシリコン（ＦｅＳｉ）中のＳｉ含有量は７５質量％である。 Table 2 shows the dephosphorization treated soot used (referred to as “dephosphorizing soot” in Table 2) and the Si and P concentrations in ordinary soot and the mixing rate of the dephosphorized soot (dephosphorization in the mixed soot). Ratio of treated soot), Si concentration and P concentration in the mixing soot, hot metal compounding ratio when the mixed soot is blown, amount of heating agent used per ton of mixed soot when the mixed soot is blown, and use The total value of the effective calorific values of all the heat-up agents (number per 1 ton of mixed soot) is shown. In addition, the steel output temperature after completion | finish of blowing is 1670-1680 degreeC. The carbonaceous material used as the heat-up agent is earthy graphite. Furthermore, Si content in the ferrosilicon (FeSi) used as a heat-rising agent is 75 mass%.
表２から分かるように、全ての実施例において、比較例に比べて昇熱剤の使用量を低減できた。実施例において使用した混合銑中のＳｉ濃度は０．１〜０．５質量％程度であり、溶銑１トン当たり約１〜５ｋｇの溶銑中Ｓｉが昇熱に寄与したと推定できる。その結果、実施例においては、いずれの場合でも溶銑１トン当たり５．０ｋｇ以下のフェロシリコン使用量で転炉を操業できた。この実施例では、フェロシリコン中のＳｉ含有量は７５質量％であるので、発熱に寄与したＳｉの量は溶銑１トン当たり３．７５ｋｇ以下となるから、溶銑１トン当たり３．７５ｋｇ以下のＳｉで転炉を操業できたことになる。 As can be seen from Table 2, in all of the examples, the amount of the heating agent used can be reduced as compared with the comparative example. The Si concentration in the mixed iron used in the examples is about 0.1 to 0.5% by mass, and it can be estimated that about 1 to 5 kg of Si in the hot metal per 1 ton of hot metal contributed to the heating. As a result, in all the examples, the converter could be operated with a ferrosilicon usage of 5.0 kg or less per ton of hot metal. In this example, since the Si content in the ferrosilicon is 75% by mass, the amount of Si that contributes to heat generation is 3.75 kg or less per ton of hot metal, so that 3.75 kg or less of Si per ton of hot metal is used. This means that the converter could be operated.
また、フェロシリコンに加えて炭素質物質もあわせて添加する場合は、炭素質物質の使用量は溶銑１トン当たり１０ｋｇ以下で転炉を操業できた。表２の例における昇熱剤添加の影響を、全昇熱剤の実効発熱量の合計値で評価すると、実施例の場合は、いずれも溶銑１トン当たり３００００ｋｃａｌ以下の昇熱剤で転炉を操業できているが、比較例ではそれ以上の昇熱剤が必要であった。これらの結果から、本発明の溶鋼の製造方法による昇熱剤の使用量の低減効果が明らかとなった。
なお、本実施例においては、吹錬中においてスロッピングは発生せず、溶銑中のＳｉ濃度を高めた場合の問題点は観測されなかった。
When a carbonaceous material was added in addition to ferrosilicon, the converter could be operated at a carbonaceous material usage of 10 kg or less per ton of hot metal. When the influence of the heating agent addition in the example of Table 2 is evaluated by the total value of the effective heat generation amount of all the heating agents, in the case of the examples, in each case, the converter is used with a heating agent of 30000 kcal or less per 1 ton of hot metal. Although it was able to operate, the comparative example required more heat-up agent. From these results, the effect of reducing the amount of heat-generating agent used by the method for producing molten steel of the present invention was clarified.
In this example, no slopping occurred during blowing, and no problems were observed when the Si concentration in the hot metal was increased.
Claims (7)
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| KR102166614B1 (en) * | 2019-05-22 | 2020-10-16 | 현대제철 주식회사 | Method for injecting heat source member for enhancement of the end point control capability of converter |
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