JP5423554B2 - Hot metal pretreatment method - Google Patents
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本発明は、鉄鋼プロセスにおいて、高炉にて出銑された溶銑を、転炉にて精錬するまでの間に行う、溶銑中の脱珪処理、脱硫処理等の溶銑予備処理に関するものである。 The present invention relates to a hot metal pretreatment such as a desiliconization process and a desulfurization process in hot metal, which is performed before the hot metal discharged in a blast furnace is refined in a converter in a steel process.
鉄鋼製造プロセスにおいて、高炉で溶解された鉄（溶銑）は、高炉から取り出し（出銑）、転炉に輸送され、転炉にて所望の鋼成分になるよう精錬される。高炉で出銑された溶銑は、トーピードカーまたは溶銑鍋等の容器によって輸送され、その中で珪素（Ｓｉ）を除去する脱珪処理、硫黄（Ｓ）を除去する脱硫処理、リン（Ｐ）を除去する脱リン処理等を行う場合がある。これらを総称して溶銑予備処理という。 In the steel manufacturing process, iron (molten metal) melted in a blast furnace is taken out from the blast furnace (unloading), transported to the converter, and refined to become a desired steel component in the converter. The hot metal discharged in the blast furnace is transported by a container such as a torpedo car or hot metal ladle, in which desiliconization to remove silicon (Si), desulfurization to remove sulfur (S), and phosphorus (P) are removed. In some cases, dephosphorization treatment is performed. These are collectively referred to as hot metal preliminary treatment.
通常出銑直後の銑鉄は、炭素飽和状態にあり、その後、トーピードカーや溶銑鍋に貯蔵し、脱珪、脱硫処理を行うため、溶銑温度が低下し、溶銑中の炭素がグラファイトとして析出する。そのため、脱珪処理後から転炉装入までの溶銑輸送中や脱硫処理中にグラフィアトが飛散し作業環境の悪化につながるだけでなく、析出したグラファイトが転炉スラグに混入し、外販上の品質にも影響を及ぼす。 Usually, the pig iron immediately after brewing is in a carbon saturated state, and then stored in a torpedo car or hot metal ladle and subjected to desiliconization and desulfurization treatment, so the hot metal temperature is lowered and the carbon in the hot metal is precipitated as graphite. For this reason, not only does GRAPHATAT scatter during the hot metal transportation from the desiliconization process to the charging of the converter or during the desulfurization process, leading to a deterioration of the working environment, but the precipitated graphite is mixed into the converter slag, resulting in It also affects quality.
そこで、溶銑からのグラファイト析出を抑える方法として、特許文献１には、脱硫効率を悪化させないように溶銑中のＳｉ含有量が０．２０％〜０．３０％になるようトーピードカー内で脱珪処理を行い、次に溶銑を溶銑鍋に移し、適正量の酸素ガスを内管より吹込みながら、外管より脱硫剤を吹き込む脱硫処理方法が提案されている。この方法により、脱硫処理中に析出することが見込まれる炭素を燃焼させることができ、グラファイトの析出を抑えることができるとしている。 Therefore, as a method for suppressing the precipitation of graphite from the hot metal, Patent Document 1 discloses that the silicon content in the hot metal is 0.20% to 0.30% so that the desulfurization efficiency is not deteriorated. Next, a desulfurization treatment method is proposed in which the hot metal is transferred to a hot metal ladle and a desulfurizing agent is blown from the outer pipe while blowing an appropriate amount of oxygen gas from the inner pipe. According to this method, carbon that is expected to be precipitated during the desulfurization treatment can be burned, and precipitation of graphite can be suppressed.
特許文献１に記載の方法は、脱硫処理における適正な酸素ガス量を２０〜３０Ｎｍ３／ｍｉｎとしている。これは、酸素量が増加するとグラファイト発生量が減少し、酸素量２０Ｎｍ３／ｍｉｎ以上では、グラファイト発生率がほぼ０％となることと、一方で酸素量が３０Ｎｍ３／ｍｉｎを超えると脱硫処理中の脱珪（Ｓｉ除去）量が増大し、転炉精錬時の熱源が低下するためである。
しかし、特許文献１で規定している酸素ガス量は、脱硫処理中におけるグラファイトの析出抑制のみを目的しており、出銑から転炉までの溶銑の状態変化や、脱珪、脱硫等の処理目的を考慮して総合的に判断されたものになっていない。そのため特許文献１の脱硫方法だけでは、実際上、溶銑の輸送中から転炉装入までのグラファイトの飛散防止効果を保証するものではない。
In the method described in Patent Document 1, an appropriate amount of oxygen gas in the desulfurization treatment is set to 20 to 30 Nm 3 / min. This is because when the amount of oxygen increases, the amount of graphite generated decreases, and when the amount of oxygen is 20 Nm 3 / min or more, the rate of graphite generation is almost 0%. On the other hand, when the amount of oxygen exceeds 30 Nm 3 / min, desulfurization treatment is performed. This is because the amount of desiliconization (Si removal) increases and the heat source during converter refining decreases.
However, the amount of oxygen gas specified in Patent Document 1 is only for the purpose of suppressing the precipitation of graphite during the desulfurization treatment, and it is possible to change the state of the hot metal from the tapping process to the converter, and to treat desiliconization, desulfurization, etc. It has not been judged comprehensively considering the purpose. Therefore, only the desulfurization method of Patent Document 1 does not actually guarantee the effect of preventing the scattering of graphite from the molten metal transport to the charging of the converter.
また、特許文献１の方法は脱硫処理のみを対象としており、脱珪処理にて投入する固体酸素としての酸化鉄粉を考慮していないため、実際は、温度低下が進み、脱珪処理後から脱硫処理開始までの間のグラファイト析出につながっている。
通常、出銑後の溶銑中珪素（Ｓｉ）含有量が高い場合は、転炉での操業に支障が出ることを回避する目的や、あるいは、転炉での副材料削減の目的により、転炉処理を行うに先だってある程度Ｓｉを除去するための脱珪処理を行うことがある。
In addition, the method of Patent Document 1 is intended only for desulfurization treatment, and does not consider iron oxide powder as solid oxygen to be input in desiliconization treatment. This leads to graphite precipitation until the start of treatment.
Usually, when the content of silicon (Si) in the hot metal after brewing is high, the converter is used for the purpose of avoiding troubles in the operation of the converter, or for the purpose of reducing secondary materials in the converter. Prior to the treatment, a silicon removal treatment for removing Si to some extent may be performed.
これは、溶銑中に酸素を混入させることにより、Ｓｉを酸化させて除去するものである。このとき、酸素ガスだけで処理を行うと、酸素ガスがランス近傍にとどまり、そのまま気泡となって表面に達するため、反応効率も低下するだけでなく、溶銑表面が大きく波立ち、溶銑飛散を引き起こす。また、溶銑内への吐出力が弱いためノズル上部が集中的に溶損するバックアタックも発生する。そのため、固体酸素分として酸化鉄粉を添加している。さらに、出銑タイミングによっては、溶銑量がまちまちであったり、鋼種によっては転炉挿入までの時間がまちまちであったりする。そのため、トーピードカーや溶銑鍋で貯蔵されている時間が異なり、脱珪処理後から転炉装入までの温度低下量も異なってくる。 This is to oxidize and remove Si by mixing oxygen into the hot metal. At this time, if the treatment is performed only with oxygen gas, the oxygen gas stays in the vicinity of the lance and reaches the surface as it is, so that not only the reaction efficiency is lowered, but also the hot metal surface is greatly swollen and causes hot metal scattering. Further, since the discharge force into the hot metal is weak, a back attack in which the upper part of the nozzle melts intensively occurs. Therefore, iron oxide powder is added as a solid oxygen content. Furthermore, the amount of hot metal varies depending on the output timing, and depending on the steel type, the time until the converter is inserted varies. Therefore, the time stored in the torpedo car or hot metal ladle is different, and the amount of temperature decrease from the desiliconization process to the charging of the converter also differs.
そこで、本発明は、出銑から転炉装入までを総合的に捉えたグラファイト析出防止策を構築することを課題とし、最適な酸素量や時間経過をも考慮した溶銑予備処理方法の提供を目的とする。 Accordingly, the present invention aims to construct a graphite precipitation prevention measure that comprehensively captures everything from tapping to charging the converter, and provides a hot metal pretreatment method that takes into account the optimal amount of oxygen and the passage of time. Objective.
本発明者らは、前記課題解決のために鋭意検討を重ねた結果、脱珪処理における酸素添加方法に着目し、脱珪処理に必要な溶銑１ｔあたりの酸素原単位（Ｎｍ３／ｔ）と、溶銑１ｔあたりのトータル酸素量に対する気体酸素の比である気酸比（以下の式で定義する）および転炉装入までの時間から、溶銑の温度低下と炭素量を予測できることを見出し、本発明をなすに至った。その要旨とするところは、以下のとおりである。 As a result of intensive studies for solving the above problems, the present inventors have paid attention to the oxygen addition method in the desiliconization process, and the oxygen intensity (Nm 3 / t) per 1 ton of hot metal necessary for the desiliconization process. From the gas-acid ratio (defined by the following formula), which is the ratio of gaseous oxygen to 1 ton of hot metal, and the time to charge the converter, the temperature drop and carbon content of the hot metal can be predicted. Invented the invention. The gist is as follows.
気酸比＝気体酸素量／（気体酸素量＋固体酸素量）
気体酸素量＝脱珪処理のために溶銑１ｔ当たりに投入する酸素ガス中の酸素量（ｋｇ ／ｔ）
固体酸素量＝脱珪処理のために溶銑１ｔ当たりに投入する酸化鉄等に含まれる酸素量 （ｋｇ／ｔ）
Gas-acid ratio = amount of gaseous oxygen / (amount of gaseous oxygen + amount of solid oxygen)
Amount of gaseous oxygen = amount of oxygen in oxygen gas (kg / t) input per 1 ton of hot metal for desiliconization treatment
Amount of solid oxygen = amount of oxygen contained in iron oxide, etc. added per ton of hot metal for desiliconization (kg / t)
（１）溶銑予備処理方法において、脱珪処理のために溶銑に投入する溶銑１ｔ当たりの酸素量である酸素原単位および気酸比、さらに溶銑が転炉に装入されるまでの予定時間から、溶銑の転炉装入時における温度と炭素濃度を予測し、前記予測した転炉装入時の溶銑温度に基づく溶銑の飽和炭素濃度が、予測した転炉装入時の溶銑の炭素濃度より大きくなるよう気酸比を決定することを特徴とする溶銑予備処理方法。 (1) In the hot metal preliminary treatment method, from the oxygen basic unit and the gas-acid ratio, which are the amount of oxygen per 1 ton of hot metal to be added to the hot metal for desiliconization, and the estimated time until the hot metal is charged into the converter Predicting the temperature and carbon concentration of the hot metal in the furnace charging, and the saturated carbon concentration of the hot metal based on the predicted hot metal temperature at the time of charging the converter is based on the predicted carbon concentration of the hot metal at the time of charging the converter. A hot metal pretreatment method characterized by determining a gas-acid ratio so as to increase.
（２）前記溶銑の転炉装入時におけるＳｉ濃度を予測し、当該予測した転炉装入時の溶銑Ｓｉ濃度が０．３％以上になるように気酸比を決定することを特徴とする請求項１に記載の溶銑予備処理方法。 (2) The present invention is characterized by predicting the Si concentration at the time of charging the molten iron into the converter and determining the gas-acid ratio so that the predicted molten iron Si concentration at the time of charging the converter is 0.3% or more. The hot metal pretreatment method according to claim 1.
（３）前記酸素原単位（Ｖ）と前記気酸比（Ｒ）との関係において
―０．０２×Ｒ＋３ ≦ Ｖ ≦ ０．０１×Ｒ＋２．５
（但し、２５≦Ｒ≦８０）
を満足することを特徴とする（１）または（２）に記載の溶銑予備処理方法。
(3) In the relationship between the oxygen basic unit (V) and the gas-acid ratio (R): −0.02 × R + 3 ≦ V ≦ 0.01 × R + 2.5
(However, 25 ≦ R ≦ 80)
The hot metal preliminary treatment method according to (1) or (2), wherein:
本発明によると、高炉溶銑の溶銑予備処理において、適正な酸素量を確保しつつ、転炉装入までのグラファイトの析出が抑制されるため、グラファイト粉塵の発生が抑制され、作業環境が著しく改善されるだけでなく、副産物としてのスラグ品質も改善するという効果を奏する。 According to the present invention, in the hot metal pretreatment of the blast furnace hot metal, the precipitation of graphite until the charging of the converter is suppressed while ensuring an appropriate amount of oxygen, so the generation of graphite dust is suppressed and the working environment is remarkably improved. In addition, the slag quality as a by-product is improved.
図１に従い、溶銑予備処理の概要を説明する。
溶銑予備処理は、転炉、二次精錬での精錬負荷を軽減するために行われ、一般に珪素（Ｓｉ）を除去する脱珪（Ｓｉ）処理、硫黄（Ｓ）を除去する脱硫処理、リン（Ｐ）を処理する脱リン処理がある。
The outline of the hot metal preliminary process will be described with reference to FIG.
The hot metal pretreatment is performed to reduce the refining load in the converter and secondary refining. Generally, desiliconization (Si) treatment for removing silicon (Si), desulfurization treatment for removing sulfur (S), phosphorus ( There is a dephosphorization treatment to treat P).
脱珪処理は、通常酸素を投入しＳｉを酸化析出させ、鋼中から除去している。そのため、酸素源として気体酸素（酸素ガス）と固体酸素を用いている。図１は、脱珪処理をトーピードカー中で行う図を示している。トーピードカー中の溶銑にランスを浸漬させ、それを通して酸素ガスを投入し、鋼中のＳｉと反応させる。しかし、前述したように、酸素ガスがランス近傍にとどまり、そのまま気泡となって表面に達するため、反応効率も低下するだけでなく、溶銑表面が大きく波立ち、トーピードカー炉体振動や溶銑飛散を引き起こし、ランス耐火物の損傷（バックアッタク）の原因ともなる。そこで、気体酸素だけでなく、固体の酸素源として、焼結ダスト等の酸化鉄粉も投入する。酸化鉄粉は、トーピードカー中において、ランスを通し窒素（Ｎ2）ガスをキャリアガスとして投入できる。
また、高炉出銑樋において溶銑に混入し、そのままトーピードカーに投入する方法もできる。固体酸素源を使用することにより、反応性を高めることが可能となり、操業性を悪化させることなく酸素供給速度を向上させることが可能となる。
脱リン処理は、一般に酸化鉄や石灰等の造滓剤を主成分とする脱リン剤を、窒素（Ｎ2）をキャリアガスとして溶銑中に吹き込み、スラグとして除去する。
In the silicon removal treatment, oxygen is usually added to oxidize and precipitate Si, which is removed from the steel. Therefore, gaseous oxygen (oxygen gas) and solid oxygen are used as the oxygen source. FIG. 1 shows a view in which the desiliconization process is performed in a torpedo car. A lance is immersed in hot metal in a torpedo car, oxygen gas is introduced through it, and it reacts with Si in steel. However, as described above, oxygen gas stays in the vicinity of the lance and reaches the surface as it is, so that not only the reaction efficiency is lowered, but also the hot metal surface is greatly waved, causing torpedo car furnace vibration and hot metal scattering, It may also cause damage (back attack) to the lance refractory. Therefore, not only gaseous oxygen but also iron oxide powder such as sintered dust is introduced as a solid oxygen source. The iron oxide powder can be charged with nitrogen (N 2 ) gas as a carrier gas through a lance in a torpedo car.
Further, it is possible to mix the molten iron in the molten iron at the blast furnace discharge and put it into the torpedo car as it is. By using a solid oxygen source, the reactivity can be increased, and the oxygen supply rate can be improved without deteriorating operability.
In the dephosphorization treatment, a dephosphorizing agent mainly composed of a iron making agent such as iron oxide or lime is generally blown into the hot metal using nitrogen (N 2 ) as a carrier gas and removed as slag.
脱硫処理は、溶銑中にＣａＯやＣａＣ２等の脱硫剤をやはり、窒素（Ｎ2）ガスをキャリアガスとして投入し、Ｓ分をスラグとして除去する。
本来は、脱硫処理では酸素は反応効率を低下させるため、酸素ガスを併用することはしないが、前述したようにグラファイトの生成抑制のためわざわざ投入する場合もある。
In the desulfurization treatment, a desulfurizing agent such as CaO or CaC 2 is introduced into the molten iron as nitrogen (N 2 ) gas as a carrier gas, and the S component is removed as slag.
Originally, in desulfurization treatment, oxygen lowers the reaction efficiency, so oxygen gas is not used together. However, as described above, there are cases where it is bothered to suppress the formation of graphite.
次に図１に従い、本発明に係る溶銑予備処理方法を説明する。
本発明は、最終的に溶銑を転炉に装入する時点で、溶銑中の飽和炭素濃度が、溶銑中の炭素濃度より大きければ、炭素（グラファイト）の析出がなく、そのためグラファイトの飛散を抑制できるものである。
転炉装入時の溶銑温度は、通常の伝熱計算式や経験値等から予測することができる。例えば、転炉装入までの予定経過時間による温度降下、容器移し替えに伴う温度降下、溶銑予備処理の各処理におけるランス等の浸漬に伴う温度降下、さらに溶銑予備処理の各処理に伴う反応熱等の温度変動を考慮して、予測することができる。当業者であれば通常の操業において行っている方法により予測することができるので、ここでは予測方法の詳細については言及しない。
Next, the hot metal pretreatment method according to the present invention will be described with reference to FIG.
In the present invention, when the hot metal is finally charged into the converter, if the saturated carbon concentration in the hot metal is larger than the carbon concentration in the hot metal, no carbon (graphite) is precipitated, and therefore, the scattering of graphite is suppressed. It can be done.
The hot metal temperature at the time of charging the converter can be predicted from normal heat transfer calculation formulas and experience values. For example, temperature drop due to the estimated elapsed time until converter charging, temperature drop due to container transfer, temperature drop due to immersion of lance in each process of hot metal pretreatment, and reaction heat accompanying each process of hot metal pretreatment It can be predicted in consideration of temperature fluctuations such as the above. Since those skilled in the art can make predictions by a method used in normal operation, details of the prediction method are not mentioned here.
溶銑中の飽和炭素濃度は、以下に示すシェンクの式により算出することができる。
シェンクの式：
飽和炭素濃度＝１．３４＋０．００２５４×温度（℃）−０．４×［Ｓｉ］
−０．３３×［Ｍｎ］−０．３３［Ｐ］
ここで、［Ｓｉ］,［Ｍｎ］,［Ｐ］の単位は（％）である。
つまり、溶銑温度とＳｉ、Ｍｎ、Ｐの濃度が分かれば、溶銑中飽和炭素濃度を予測することができる。
The saturated carbon concentration in the hot metal can be calculated by the following Schenck equation.
Schenck's formula:
Saturated carbon concentration = 1.34 + 0.00254 × temperature (° C.) − 0.4 × [Si]
−0.33 × [Mn] −0.33 [P]
Here, the unit of [Si], [Mn], [P] is (%).
That is, if the hot metal temperature and the concentrations of Si, Mn, and P are known, the saturated carbon concentration in the hot metal can be predicted.
本発明者らは、鋭意検討した結果、脱珪処理中におけるＳｉ、Ｍｎ、Ｐの各元素における酸素利用効率が、気体酸素量とトータル酸素量との比である気酸比（以下、Ｒで示す場合がある。）との間に強い相関があることを見出した。ここで気酸比（Ｒ）とは、以下の式に示すように、気体酸素量をトータル酸素量（気体酸素量と固体酸素量の合計酸素量）で除したものをいう。
気酸比（Ｒ）＝気体酸素量／（気体酸素量＋固体酸素量）
As a result of intensive studies, the present inventors have determined that the oxygen utilization efficiency of each element of Si, Mn, and P during the desiliconization treatment is a gas-acid ratio (hereinafter referred to as R). It was found that there is a strong correlation. Here, the gas-acid ratio (R) means a value obtained by dividing the amount of gaseous oxygen by the total amount of oxygen (total amount of oxygen of gaseous oxygen and solid oxygen) as shown in the following equation.
Gas-acid ratio (R) = gaseous oxygen amount / (gaseous oxygen amount + solid oxygen amount)
前述したように、気体酸素（酸素ガス）と固体酸素（酸化鉄粉等）では、溶銑中での反応に差があるため、気酸比が各元素の酸化反応効率に強く影響すると考えられる。ここで発明者らは、各元素の反応量と気酸比の関係を実験により追及した。その結果、炭素（Ｃ）、珪素（Ｓｉ）、マンガン（Ｍｎ）、リン（Ｐ）の酸化反応は気酸比と強い相関があり、酸化反応量は投入酸素量と気酸比で予測できることが分かった。そこで、実験により、各成分の酸化反応量を気酸比および投入酸素量の関数として導いた。 As described above, gas oxygen (oxygen gas) and solid oxygen (iron oxide powder, etc.) have a difference in reaction in the hot metal, so it is considered that the gas-acid ratio strongly affects the oxidation reaction efficiency of each element. Here, the inventors investigated the relationship between the reaction amount of each element and the gas-acid ratio through experiments. As a result, the oxidation reaction of carbon (C), silicon (Si), manganese (Mn), and phosphorus (P) has a strong correlation with the gas-acid ratio, and the oxidation reaction amount can be predicted by the input oxygen amount and the gas-acid ratio. I understood. Therefore, the amount of oxidation reaction of each component was derived by experiments as a function of the gas-acid ratio and the amount of input oxygen.
結果として、脱珪処理で投入した全酸素量が分かれば、各成分の酸素との反応による濃度変化が、気酸比と投入酸素量との関係で予測されることが分かった。
ここで脱珪処理での投入酸素量は、一般に溶銑１ｔ当たりの酸素原単位（Ｎｍ3／ｔ）（以下、Ｖとして示す場合がある。）として表すことができる。
As a result, it was found that if the total amount of oxygen input in the desiliconization process is known, the concentration change due to the reaction of each component with oxygen is predicted in relation to the gas-acid ratio and the amount of input oxygen.
Here, the amount of oxygen input in the desiliconization treatment can be generally expressed as an oxygen basic unit (Nm 3 / t) per 1 ton of molten iron (hereinafter sometimes referred to as V).
酸素原単位（Ｎｍ3／ｔ）を用いたときの炭素の濃度変化分（ΔＣ）は、例えば以下の式で表される。
ΔＣ＝（０．０００１０４×Ｒ＋０．０３８）×Ｖ
同様に珪素（Ｓｉ）の濃度変化分（ΔＳｉ）は、
ΔＳｉ＝（−０．０００１３×Ｒ＋０．０６４）×Ｖ
マンガン（Ｍｎ）の濃度変化分（ΔＭｎ）は、
ΔＭｎ＝（−０．００００７９×Ｒ＋０．０１０）×Ｖ
リン（Ｐ）の濃度変化分（ΔＰ）は、
ΔＰ＝（−０．００００１３×Ｒ＋０．００１６）×Ｖ
で表される。
The amount of change in carbon concentration (ΔC) when the oxygen basic unit (Nm 3 / t) is used is expressed by the following equation, for example.
ΔC = (0.000104 × R + 0.038) × V
Similarly, the change in concentration of silicon (Si) (ΔSi) is
ΔSi = (− 0.00013 × R + 0.064) × V
The concentration change (ΔMn) of manganese (Mn) is
ΔMn = (− 0.000079 × R + 0.010) × V
The concentration change (ΔP) of phosphorus (P) is
ΔP = (− 0.000013 × R + 0.0016) × V
It is represented by
なお、炭素以外のＳｉ，Ｍｎ，Ｐは、気酸比に対して負の相関が認められる。それは、これら元素の酸化は、吸熱反応であり、低温の方が反応が進むためと考えられ、気酸比が小さくなるとき、つまり固体酸素量が相対的に増えるときは、ミクロ的に固体酸素近傍の温度が低下するため、これら元素の酸化反応が進むのではないかと考えられる。 In addition, Si, Mn, and P other than carbon have a negative correlation with the gas-acid ratio. It is thought that the oxidation of these elements is an endothermic reaction, and the reaction proceeds at a lower temperature. When the gas-acid ratio decreases, that is, when the amount of solid oxygen increases relatively, microscopic solid oxygen It is thought that the oxidation reaction of these elements proceeds because the temperature in the vicinity decreases.
次に各元素濃度の初期値として、脱珪処理前の溶銑中の各元素濃度を用いる。これは、脱珪処理前にサンプリングをすることにより、温度と各元素の濃度を測定することにより求められる。このサンプリングは、通常の操業において行われていることであるので、このサンプリングデータを使うことで十分である。 Next, each element concentration in the hot metal before the desiliconization treatment is used as an initial value of each element concentration. This is calculated | required by measuring temperature and the density | concentration of each element by sampling before a desiliconization process. Since this sampling is performed in a normal operation, it is sufficient to use this sampling data.
以上のことから、溶銑の転炉装入時の温度と、各成分濃度を予測することができる。この予測した結果、溶銑の転炉装入時の飽和炭素濃度が、溶銑中の炭素濃度予測値とより大きければ、炭素（グラファイト）の析出がなく、そのためグラファイトの飛散が抑制できることになる。 From the above, it is possible to predict the temperature of the hot metal in the converter and the concentration of each component. As a result of the prediction, if the saturated carbon concentration at the time of charging the hot metal into the converter is larger than the predicted value of the carbon concentration in the hot metal, no carbon (graphite) is precipitated, and therefore, the scattering of graphite can be suppressed.
もし、溶銑中の炭素濃度予測値が溶銑の転炉装入時の飽和炭素濃度より大きければ、その過剰となった分の炭素（グラファイト）が析出するため、グラファイトの飛散が発生することとなる。その場合、酸素原単位（Ｖ）や、気酸比（Ｒ）を変化させ、再度、溶銑中の各成分の濃度変化や溶銑の温度降下から溶銑の転炉装入時における飽和炭素濃度と溶銑中の炭素濃度を予測し、比較を行い、飽和炭素濃度の方が大きくなるまで、これを繰り返す。 If the predicted value of the carbon concentration in the hot metal is larger than the saturated carbon concentration at the time of charging of the hot metal into the converter, the excess carbon (graphite) will be deposited, resulting in the scattering of graphite. . In that case, the oxygen intensity (V) and the gas-acid ratio (R) are changed, and the saturated carbon concentration and the hot metal at the time of charging the hot metal into the converter from the change in the concentration of each component in the hot metal and the temperature drop of the hot metal. The carbon concentration inside is predicted and compared, and this is repeated until the saturated carbon concentration is higher.
これにより、脱珪処理での酸素量のコントロールだけで、溶銑予備処理に必要な酸素量を考慮しつつグラファイトの発生と飛散を抑制する溶銑予備処理を行うことが可能となる。
また、脱珪処理は、転炉における負荷軽減のために珪素（Ｓｉ）を除去するが、過度に除去しすぎると、転炉における熱源が低下するため、Ｓｉ濃度は０．２％、望ましくは０．３％程度にした方がよい。そのため、溶銑の転炉装入時の珪素（Ｓｉ）濃度が０．２％未満にならないよう、望ましくは０．３％未満にならないよう、珪素処理での酸素量、気酸比を決定することが望ましい。
Accordingly, it is possible to perform the hot metal pretreatment for suppressing the generation and scattering of graphite while taking into consideration the amount of oxygen necessary for the hot metal pretreatment only by controlling the amount of oxygen in the desiliconization treatment.
Further, the silicon removal treatment removes silicon (Si) to reduce the load in the converter, but if it is excessively removed, the heat source in the converter decreases, so the Si concentration is 0.2%, preferably It should be about 0.3%. Therefore, determine the amount of oxygen and gas-acid ratio in the silicon treatment so that the silicon (Si) concentration when the molten iron is charged into the converter is not less than 0.2%, preferably not less than 0.3%. Is desirable.
次に、実際の脱珪処理前の溶銑を用いて、本発明によりグラファイト発生を抑制できる酸素原単位および気酸比を求め、脱珪処理を行った実施例を示す。
実施例は、複数のトーピードカーに受けた同一出銑タイミングの溶銑を用いて行った。それぞれ、本発明に基づきグラファイトが発生せず、転炉装入時のＳｉ濃度が０．３％未満とならないよう、珪素処理での酸素量と気酸比を決定して行った。グラファイトの飛散状況については、溶銑予備処理の各工程と、溶銑の転炉装入において、目視にて行った。
Next, using the hot metal before the actual desiliconization treatment, an oxygen basic unit and a gas-acid ratio capable of suppressing the generation of graphite according to the present invention are obtained, and an embodiment in which the desiliconization treatment is performed is shown.
The example was performed using hot metal having the same output timing received by a plurality of torpedo cars. In accordance with the present invention, the oxygen amount and gas-acid ratio in the silicon treatment were determined so that graphite was not generated and the Si concentration at the time of charging the converter was not less than 0.3%. About the scattering state of the graphite, it carried out visually in each process of hot metal preliminary treatment, and the furnace charging of hot metal.
脱珪処理前の溶銑状況
溶銑温度：１４５０℃
溶銑成分：Ｃ ：４．６５％（シェンクの式から求めた飽和炭素濃度）
Ｓｉ：０．６０％
Ｍｎ：０．３０％
Ｐ ：０．１０％
Hot metal status before desiliconization Hot metal temperature: 1450 ° C
Hot metal component: C: 4.65% (saturated carbon concentration determined from Schenck's equation)
Si: 0.60%
Mn: 0.30%
P: 0.10%
＜実施例１＞
本発明により求めた酸素原単位：３Ｎｍ３／ｍｉｎ
本発明により求めた気酸比 ：８０％
転炉装入時の溶銑温度（予測） ：１４２０℃
転炉装入時の飽和炭素濃度 ：４．６４％
転炉装入時の炭素濃度（予測） ：４．５１％
転炉装入時のＳｉ濃度（予測）：０．４４％
転炉装入時のＳｉ濃度（実測）：０．４２％
グラファイト発生は非常に軽微であり粉塵も少なく、本発明の効果を確認した。
<Example 1>
Oxygen intensity determined by the present invention: 3 Nm 3 / min
Gas-acid ratio determined by the present invention: 80%
Hot metal temperature at the time of converter charging (prediction): 1420 ° C
Saturated carbon concentration when the converter is charged: 4.64%
Carbon concentration at the time of converter charging (forecast): 4.51%
Si concentration at the time of converter charging (forecast): 0.44%
Si concentration at the time of converter charging (actual measurement): 0.42%
The generation of graphite was very slight and there was little dust, and the effect of the present invention was confirmed.
＜実施例２＞
本発明により求めた酸素原単位：３Ｎｍ３／ｍｉｎ
本発明により求めた気酸比 ：２５％
転炉装入時の溶銑温度（予測） ：１３８５℃
転炉装入時の飽和炭素濃度 ：４．５７％
転炉装入時の炭素濃度（予測） ：４．５３％
転炉装入時のＳｉ濃度（予測）：０．４２％
転炉装入時のＳｉ濃度（実測）：０．４１％
グラファイト発生は非常に軽微であり粉塵も少なく、本発明の効果を確認した。
<Example 2>
Oxygen intensity determined by the present invention: 3 Nm 3 / min
Gas-acid ratio determined by the present invention: 25%
Hot metal temperature at the time of converter charging (prediction): 1385 ° C
Saturated carbon concentration when the converter is charged: 4.57%
Carbon concentration at the time of converter charging (forecast): 4.53%
Si concentration at the time of converter charging (forecast): 0.42%
Si concentration at the time of charging the converter (actual measurement): 0.41%
The generation of graphite was very slight and there was little dust, and the effect of the present invention was confirmed.
＜実施例３＞
本発明により求めた酸素原単位：１．５Ｎｍ３／ｍｉｎ
本発明により求めた気酸比 ：８０％
転炉装入時の溶銑温度（予測） ：１４１０℃
転炉装入時の飽和炭素濃度 ：４．５８％
転炉装入時の炭素濃度（予測） ：４．５７％
転炉装入時のＳｉ濃度（予測）：０．５２％
転炉装入時のＳｉ濃度（実測）：０．５３％
グラファイト発生は非常に軽微であり粉塵も少なく、本発明の効果を確認した。
<Example 3>
Oxygen intensity determined by the present invention: 1.5 Nm 3 / min
Gas-acid ratio determined by the present invention: 80%
Hot metal temperature at the time of charging the converter (forecast): 1410 ° C
Saturated carbon concentration at the time of converter charging: 4.58%
Carbon concentration at the time of charging the converter (forecast): 4.57%
Si concentration at the time of charging the converter (forecast): 0.52%
Si concentration at the time of charging the converter (actual measurement): 0.53%
The generation of graphite was very slight and there was little dust, and the effect of the present invention was confirmed.
＜実施例４＞
本発明により求めた酸素原単位：２Ｎｍ３／ｍｉｎ
本発明により求めた気酸比 ：５０％
転炉装入時の溶銑温度（予測） ：１４００℃
転炉装入時の飽和炭素濃度 ：４．５８％
転炉装入時の炭素濃度（予測） ：４．５６％
転炉装入時のＳｉ濃度（予測）：０．４８％
転炉装入時のＳｉ濃度（実測）：０．４７％
グラファイト発生は非常に軽微であり粉塵も少なく、本発明の効果を確認した。
<Example 4>
Oxygen intensity determined by the present invention: 2 Nm 3 / min
Gas-acid ratio determined by the present invention: 50%
Hot metal temperature at the time of converter charging (prediction): 1400 ° C
Saturated carbon concentration at the time of converter charging: 4.58%
Carbon concentration at the time of charging the converter (forecast): 4.56%
Si concentration at the time of charging the converter (forecast): 0.48%
Si concentration at the time of charging the converter (actual measurement): 0.47%
The generation of graphite was very slight and there was little dust, and the effect of the present invention was confirmed.
＜実施例５＞
本発明により求めた酸素原単位：３．５Ｎｍ３／ｍｉｎ
本発明により求めた気酸比 ：８０％
転炉装入時の溶銑温度（予測） ：１４２３℃
転炉装入時の飽和炭素濃度 ：４．６６％
転炉装入時の炭素濃度（予測） ：４．４９％
転炉装入時のＳｉ濃度（予測）：０．４１％
転炉装入時のＳｉ濃度（実測）：０．４２％
グラファイト発生は非常に軽微であり粉塵も少なく、本発明の効果を確認した。
<Example 5>
Oxygen intensity determined by the present invention: 3.5 Nm 3 / min
Gas-acid ratio determined by the present invention: 80%
Hot metal temperature at the time of converter charging (prediction): 1423 ° C
Saturated carbon concentration when the converter is charged: 4.66%
Carbon concentration at the time of converter charging (prediction): 4.49%
Si concentration at the time of charging the converter (forecast): 0.41%
Si concentration at the time of converter charging (actual measurement): 0.42%
The generation of graphite was very slight and there was little dust, and the effect of the present invention was confirmed.
上記実施例１〜５の脱珪処理前の溶銑状況は、一般的な溶銑状況である。高炉の操業状態によって若干の変動はあるが、本実施例の溶銑状況を基にして、グラファイト発生を抑制でき、かつＳｉ濃度が過少にならない酸素原単位（Ｖ）と気酸比（Ｒ）の関係をまとめたのが、表１である。 The hot metal situation before the desiliconization treatment in Examples 1 to 5 is a general hot metal situation. Although there are some fluctuations depending on the operating state of the blast furnace, the oxygen basic unit (V) and the gas-acid ratio (R) of the graphite concentration can be suppressed and the Si concentration does not become excessive, based on the hot metal situation of this example. Table 1 summarizes the relationship.
図２に表１の結果をまとめた。図２は、表１と同様、×はグラファイト析出を、△はＳｉ濃度過少（０．３％未満）を、○は予測上グラファイトの析出もなく、Ｓｉ濃度も過少とならない条件を示す。
図２から、グラファイト析出を抑制するには、
−Ｒ／５０＋３ ≦ Ｖ
であり、Ｓｉ濃度過少を回避するためには、
Ｖ ≦ Ｒ／１００＋２．５
である。従って、一般的な溶銑においては、
−Ｒ／５０＋３ ≦ Ｖ ≦ Ｒ／１００＋２．５
となるような酸素原単位（Ｖ）と気酸比（Ｒ）の関係であれば、グラファイトの析出を抑制した溶銑予備処理が可能となる。
The results of Table 1 are summarized in FIG. In FIG. 2, as in Table 1, “x” indicates graphite precipitation, “Δ” indicates that the Si concentration is too low (less than 0.3%), and “◯” indicates the condition that no graphite is precipitated and the Si concentration is not too low.
From FIG. 2, to suppress graphite precipitation,
−R / 50 + 3 ≦ V
In order to avoid the Si concentration being too low,
V ≦ R / 100 + 2.5
It is. Therefore, in general hot metal,
−R / 50 + 3 ≦ V ≦ R / 100 + 2.5
If the relationship between the oxygen basic unit (V) and the gas-acid ratio (R) is as follows, hot metal preliminary treatment with suppressed graphite precipitation becomes possible.
以上、本発明について説明した。しかし、本発明の実施態様は、本発明の技術範囲に含まれるものであれば、いかなる態様をとることもでき、前記態様に限らないことは言うまでもない。 The present invention has been described above. However, the embodiment of the present invention can take any form as long as it is included in the technical scope of the present invention, and it is needless to say that the embodiment is not limited to the above aspect.
本発明は、製鉄プロセスのおける溶銑予備処理工程において利用することができる。 The present invention can be used in a hot metal pretreatment process in an iron making process.
Claims (3)
気酸比＝気体酸素量／（気体酸素量＋固体酸素量）
気体酸素量＝脱珪処理のために溶銑１ｔ当たりに投入する酸素ガス中の酸素量（ｋｇ）
固体酸素量＝脱珪処理のために溶銑１ｔ当たりに投入する酸化鉄等に含まれる酸素量（ｋｇ）
In the hot metal pretreatment method, the oxygen basic unit, which is the amount of oxygen per 1 ton of hot metal to be introduced into the hot metal for desiliconization, the gas-acid ratio defined by the following formula, and further, until the hot metal is charged into the converter Based on the estimated time, the temperature and carbon concentration at the time of the furnace charging of the hot metal are predicted, and the saturated carbon concentration of the hot metal based on the predicted hot metal temperature at the time of charging the converter is the predicted value of the hot metal at the time of charging the converter. A hot metal pretreatment method characterized by determining a gas-acid ratio so as to be larger than a carbon concentration.
Gas-acid ratio = amount of gaseous oxygen / (amount of gaseous oxygen + amount of solid oxygen)
Amount of gaseous oxygen = amount of oxygen in oxygen gas (kg) input per ton of hot metal for desiliconization
Solid oxygen amount = Oxygen amount (kg) contained in iron oxide, etc. to be added per ton of hot metal for desiliconization treatment
The Si concentration at the time of furnace charging of the hot metal is predicted, and the gas-acid ratio is determined so that the predicted hot metal Si concentration at the time of charging of the converter becomes 0.3% or more. The hot metal preliminary treatment method according to 1.
―０．０２×Ｒ＋３ ≦ Ｖ ≦ ０．０１×R＋２．５
（但し、２５≦Ｒ≦８０）
を満足することを特徴とする請求項１または２に記載の溶銑予備処理方法。 In the relationship between the oxygen basic unit (V) and the gas-acid ratio (R), −0.02 × R + 3 ≦ V ≦ 0.01 × R + 2.5
(However, 25 ≦ R ≦ 80)
The hot metal preliminary treatment method according to claim 1 or 2, wherein:
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