JP2016060964A - Desiliconization method of molten pig iron - Google Patents
Desiliconization method of molten pig iron Download PDFInfo
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本発明は、溶銑の脱珪処理を効率的に行う技術に関する。 The present invention relates to a technique for efficiently performing desiliconization processing of hot metal.
高炉から出銑された溶銑は、炭素を４〜５％（本明細書において化学組成または濃度に関する「％」は特に断りがない限り「質量％」を意味する）含有しており、次工程である製鋼工程において酸素を吹き込むことにより脱炭されて鋼となる。この時、反応容器内に生石灰やドロマイト等の精錬剤（「媒溶材」、「フラックス」などとも称される）を添加することにより溶銑中のりんも除去される。除去されたりん等の元素は酸化物として、精錬剤ともにスラグを形成する。 The hot metal discharged from the blast furnace contains 4 to 5% of carbon (in this specification, “%” relating to the chemical composition or concentration means “% by mass” unless otherwise specified), and in the next step In a certain steelmaking process, oxygen is blown to decarburize the steel. At this time, phosphorus in hot metal is also removed by adding a refining agent (also referred to as “medium solvent”, “flux”, etc.) such as quick lime and dolomite into the reaction vessel. The removed elements such as phosphorus form slag together with the refining agent as oxides.
このような脱りん反応には、所定のスラグ中ＣａＯ／ＳｉＯ２値（以下、この値を「塩基度」と称する）が必要であることが知られる。溶銑中Ｓｉ濃度が高いとＳｉの優先酸化によりＳｉＯ２が形成され、必然的にＣａＯを含有する精錬剤の使用量が増加するため精錬コストの悪化につながる。また、精錬剤使用量の増加に伴い、スラグ量が増加してしまうため、スラグ処理コストも同時に悪化する。 It is known that such a dephosphorization reaction requires a predetermined CaO / SiO 2 value in the slag (hereinafter, this value is referred to as “basicity”). If the Si concentration in the hot metal is high, SiO 2 is formed due to the preferential oxidation of Si, and the amount of the refining agent containing CaO is inevitably increased, leading to deterioration in refining costs. Moreover, since the amount of slag will increase with the increase in the amount of refining agent used, the slag processing cost will also deteriorate simultaneously.
このため、一般的に、脱りん・脱炭工程の前に脱珪処理を行う方法が採用されている。この脱珪処理は、溶銑中のＳｉを酸化することにより行われる。Ｓｉを酸化するためには気体酸素が用いられることもあるが、通常は酸化鉄等の固体脱珪材が使用される。固体脱珪材は、高炉から出銑された溶銑樋、溶銑の搬送容器（例えば混銑車）、あるいは脱珪処理容器（例えば取鍋）など様々な段階で添加され、添加方法も、単なる上置、吹込み、溶銑が落下する部分への添加等が適宜選択される。 For this reason, the method of performing a desiliconization process is generally employ | adopted before a dephosphorization and a decarburization process. This desiliconization process is performed by oxidizing Si in the hot metal. Gaseous oxygen may be used to oxidize Si, but a solid desiliconizing material such as iron oxide is usually used. Solid desiliconization material is added at various stages such as hot metal discharged from a blast furnace, molten iron transport container (for example, a kneading car), or desiliconization processing container (for example, a ladle). Blowing, addition to the part where the hot metal falls, etc. are appropriately selected.
脱珪反応により生成したＳｉＯ２と脱珪材中の酸化鉄等からなる脱珪スラグが溶銑上に存在しており、この脱珪スラグと溶銑の接触面において、溶銑中炭素とスラグ中の酸化鉄の反応によりＣＯガスが生成する。脱珪スラグはＳｉＯ２を主体とした高粘性のスラグであるため、生成したＣＯガスはスラグ中を短時間で通過することが容易でなく、スラグ中に気泡として捕捉されてしまい、スラグ体積が増加してしまう。この現象はスラグフォーミングと呼ばれる。 Desiliconized slag consisting of SiO 2 produced by the desiliconization reaction and iron oxide in the desiliconized material is present on the hot metal, and carbon in the hot metal and oxidation in the slag are brought into contact with the desiliconized slag and hot metal. CO gas is generated by the reaction of iron. Since the desiliconized slag is a highly viscous slag mainly composed of SiO 2 , the generated CO gas cannot easily pass through the slag in a short time, but is trapped as bubbles in the slag, and the slag volume is increased. It will increase. This phenomenon is called slag forming.
搬送容器から、取鍋型でかつ溶銑保持時のフリーボード（溶銑浴面から脱珪処理容器の装入口までの距離）が１５００ｍｍ以下の脱珪処理容器に払い出す際に固体脱珪材を添加する場合、スラグフォーミングが激しくなると、溶銑の払い出しを中断せざるを得なくなるので、溶銑払い出し時間の増加に伴う能率悪化や、脱珪スラグの容器外への溢出や飛散、また、そのフォーミングした脱珪スラグ中もしくは脱珪スラグ上に脱珪材が捕捉されることで、フォーミングが助長されたり、脱珪効率が低下してしまうという問題があった。 Solid desiliconization material is added when discharging from a transfer container to a desiliconization container with a ladle type and a free board (distance from the hot metal bath surface to the inlet of the desiliconization process container) when holding the molten iron. If the slag forming becomes intense, the hot metal discharge must be interrupted. There has been a problem that forming is promoted or desiliconization efficiency is reduced by capturing the desiliconized material in or on the desiliconized slag.
このようなスラグフォーミングの発生を抑制するために、従来より種々の方法が開示されており、例えば、特許文献１に開示されるようなコークス粉を添加して破泡を促進させる方法や、特許文献２に開示されるような金属Ａｌを添加して脱珪スラグ中酸化鉄を還元する方法、さらには、特許文献３に開示される容器への受銑初期に脱珪材を投入した後、生成するＳｉＯ２量に応じて生石灰等の塩基性酸化物を添加して、生成する脱珪スラグの塩基度を所定の値に調整する方法等がある。 In order to suppress the occurrence of such slag foaming, various methods have been conventionally disclosed. For example, a method of adding coke powder as disclosed in Patent Document 1 to promote foam breaking, A method of reducing metal oxide in desiliconized slag by adding metal Al as disclosed in Document 2, and further, after introducing a desiliconized material in the initial stage of receiving the container disclosed in Patent Document 3, There is a method of adding a basic oxide such as quicklime according to the amount of SiO 2 to be generated and adjusting the basicity of the desiliconized slag to be generated to a predetermined value.
しかし、特許文献１，２に開示される方法は、いずれも、スラグフォーミング抑制のために添加するコークス粉や金属Ａｌの効果はスラグフォーミングを抑制するのみであり、脱Ｓｉ反応には効果がなく、脱Ｓｉ反応を低下させてしまう悪影響を及ぼすおそれがある。また，特許文献３に開示される方法は、脱珪スラグの塩基度を調整するために生石灰等を使用しなければならず、結局、精錬コストの悪化とスラグ量の増加を招いてしまうという問題がある。 However, in any of the methods disclosed in Patent Documents 1 and 2, the effect of coke powder and metal Al added for suppressing slag forming is only to suppress slag forming, and has no effect on de-Si reaction. There is a risk of adversely affecting the Si removal reaction. In addition, the method disclosed in Patent Document 3 must use quick lime or the like to adjust the basicity of desiliconized slag, which eventually leads to deterioration in refining costs and an increase in the amount of slag. There is.
一方で、特許文献４，５には、高炉から出銑した溶銑の搬送容器から脱珪処理容器に払い出す際の溶銑流に対して２〜４ｍｍに調整した脱珪材を吹き付けるか、もしくは上方から添加した上で、払出し完了後にバブリングおよびインジェクション脱硫を行うことにより脱珪効率を向上する方法が開示されている。 On the other hand, in Patent Documents 4 and 5, the desiliconization material adjusted to 2 to 4 mm is sprayed on the molten iron flow when the molten metal is discharged from the molten iron conveyance container from the blast furnace to the desiliconization processing container, or above. A method for improving desiliconization efficiency is disclosed by adding bubbling and injection desulfurization after the addition is completed.
特許文献４，５により開示される方法によれば、脱珪材と溶銑との反応を促進させ、払出し速度にマッチした酸素供給を行うことができることから、脱珪効率が向上できるとされている。しかし、特許文献４，５には、溶銑払出し速度と脱珪材投入速度の適切な関係や払出し中のフォーミング抑制に関する記載がない。また、吹き付けを行うために粉体を取り扱う設備が必要となり、設備費が嵩む。 According to the methods disclosed in Patent Documents 4 and 5, it is said that the desiliconization efficiency can be improved because the reaction between the desiliconization material and the hot metal can be promoted and the oxygen supply matched to the dispensing speed can be performed. . However, Patent Documents 4 and 5 do not describe an appropriate relationship between the hot metal discharge speed and the desiliconization material charging speed and the suppression of forming during discharge. In addition, equipment for handling the powder is necessary for spraying, which increases equipment costs.
それに対して、吹き付けを行わない場合は、最も安価に脱珪設備を導入できるものの、搬送容器および脱珪処理容器中の溶銑量や払出し速度によって脱珪材が溶銑流に巻き込まれず、スラグフォーミングが助長され、脱珪効率が著しく低下するという課題がある。 On the other hand, if spraying is not performed, desiliconization equipment can be introduced at the lowest cost, but the desiliconized material is not caught in the hot metal flow by the amount of molten metal and the discharge speed in the transfer container and desiliconization processing container, and slag forming is not performed. There is a problem that the desiliconization efficiency is significantly reduced.
これに加えて、特許文献４，５に開示される方法では、ガスバブリングとインジェクション脱硫によって未反応脱珪材の反応を促進させる。しかし、ガスバブリングを行うには、加圧ラインおよび粉体供給ライン等が必要となり、高額な設備になり、加えて、ガスバブリングに用いる耐火物のランスは消耗品であるためにランニングコストも嵩む。また、インジェクション設備が必要であるが、機械式撹拌法による脱硫がインジェクション法と並び一般的となっている昨今では、インジェクション脱硫設備を保有しない場合も多く、この場合には設備投資が多額となるという課題もある。 In addition, in the methods disclosed in Patent Documents 4 and 5, the reaction of the unreacted desiliconized material is promoted by gas bubbling and injection desulfurization. However, in order to perform gas bubbling, a pressurization line, a powder supply line, etc. are required, which is expensive equipment. In addition, the refractory lance used for gas bubbling is a consumable item, which increases the running cost. . In addition, although injection equipment is required, desulfurization by mechanical stirring method is common along with the injection method, and in recent years, there are many cases that do not have injection desulfurization equipment, and in this case, capital investment is large. There is also a problem.
本発明の目的は、このような脱珪処理に際して見られる課題に鑑みてなされたものであり、スラグフォーミング抑制を安定的に行い、かつ、安価に脱珪材反応効率を向上させることができる溶銑の脱珪処理方法を提供することである。 The object of the present invention has been made in view of the problems seen in such desiliconization treatment, and can stably suppress slag forming and improve the desiliconization reaction efficiency at low cost. It is to provide a silicon removal treatment method.
上記の目的を達成するために、本発明に係る溶銑の脱珪方法は、以下の構成を採用する。 In order to achieve the above object, the hot metal desiliconization method according to the present invention employs the following configuration.
（１）高炉から出銑した溶銑を、搬送容器から脱珪処理容器に払い出す際の溶銑流に対して脱珪材を添加する溶銑の脱珪処理方法において、前記脱珪材として平均粒径５ｍｍ以上１０ｍｍ以下の焼結鉱を１０ｋｇ／溶銑ｔ以下の範囲で使用し、かつ、前記脱珪剤の添加速度と払出し速度を、下記（１）式を満足する範囲とすることを特徴とする溶銑の脱珪処理方法。 (1) In the hot metal desiliconization method of adding hot metal discharged from a blast furnace to the hot metal flow when the hot metal discharged from the transport container to the desiliconization processing vessel, the average particle size as the desiliconized material A sintered ore of 5 mm or more and 10 mm or less is used in a range of 10 kg / mol t or less, and the addition rate and the discharge rate of the desiliconizing agent are set to satisfy the following formula (1). Hot metal desiliconization method.
ただし、Ｖ：脱珪材中酸素体積（Ｎｌ／ｋｇ）、ｖ：脱珪材添加速度（ｋｇ／ｍｉｎ）、ｕ：溶銑払出し速度（ｔ／ｍｉｎ）、［Ｓｉ］ｉ：脱珪前溶銑中Ｓｉ濃度（質量％）（ただし、［Ｓｉ］ｉ≧０．２０％）であり、脱珪材中酸素体積とは，脱珪材中に含まれるＦｅＯおよびＦｅ２Ｏ３が分解した際に発生するＯ２ガスの標準状態での体積を、脱珪材単位質量当たりで表す。 V: oxygen volume in desiliconized material (Nl / kg), v: desiliconized material addition rate (kg / min), u: hot metal discharge rate (t / min), [Si] i : hot metal before desiliconization Si concentration (mass%) (however, [Si] i ≧ 0.20%), and the oxygen volume in the desiliconized material is generated when FeO and Fe 2 O 3 contained in the desiliconized material are decomposed. The volume of O 2 gas in the standard state is expressed per unit mass of desiliconized material.
（２）脱珪材の添加を、溶銑払出し開始時から、払出しに要する時間の７０％経過時までの間に行いつつ、かつ、払出し完了後にバブリング処理を実施しない１項に記載の溶銑の脱珪処理方法。 (2) The removal of the hot metal as described in item 1, wherein the desiliconization material is added from the start of the hot metal discharge until 70% of the time required for the discharge and the bubbling process is not performed after the completion of the discharge. Silica treatment method.
本発明において、「平均粒径」とはレーザー回折・散乱法等によって求めた粒度分布における積算値５０％での粒径を意味し、「添加速度」とは、脱珪容器内への脱珪材の添加質量を、脱珪材の添加開始から添加終了までの時間で除することにより求められる値を意味し、「払出し速度」とは、脱珪容器内への溶銑の払出し質量を、溶銑の払出し開始から払出し終了までの時間で除することにより求められる値を意味する。 In the present invention, “average particle size” means the particle size at an integrated value of 50% in the particle size distribution obtained by laser diffraction / scattering method, etc., and “addition rate” means desiliconization into the desiliconization vessel. The value obtained by dividing the added mass of the material by the time from the start of addition of the desiliconized material to the end of the addition, and the "dispensing speed" is the amount of molten iron discharged into the desiliconized container. Means a value obtained by dividing by the time from the start of payout to the end of payout.
さらに、本明細書において「脱珪反応効率」とは、脱珪材中酸素体積に占める、脱珪に使用された酸素体積の割合を百分率で表示した指標である。 Furthermore, “desiliconization reaction efficiency” in the present specification is an index that indicates the percentage of the oxygen volume used for desiliconization in the oxygen volume in the desiliconized material as a percentage.
本発明により、高炉から出銑された溶銑の搬送容器から脱珪処理容器に溶銑を払い出す際にその溶銑流へ焼結鉱を添加する溶銑の脱珪処理方法において、焼結鉱の粒径を調整し、かつ焼結鉱投入速度を調整することにより、スラグフォーミング抑制を安定的に行い、脱珪材反応効率を向上させることができる。 According to the present invention, in the hot metal desiliconization method of adding sintered ore to the hot metal flow when the hot metal is discharged from the hot metal transfer container discharged from the blast furnace to the desiliconization processing container, the particle size of the sintered ore By adjusting the sinter and adjusting the sinter feed rate, it is possible to stably suppress slag forming and improve the desiliconization reaction efficiency.
本発明において、さらに、脱珪反応効率を高めたい場合には、上記した本発明の特徴を活かしつつ、焼結鉱の添加を溶銑払出し開始時から、払出し全期間に占める７０％経過時までに焼結鉱の投入を完了させ、かつ溶銑払出し後のバブリング処理を省略することによって、バブリングに要する時間を含む脱珪処理の所要時間を短縮することができる。 In the present invention, when it is desired to further improve the desiliconization reaction efficiency, the addition of the sintered ore is started from the start of the hot metal discharge from the start of the hot metal discharge to the time when 70% occupies the entire discharge period. By completing the charging of the sintered ore and omitting the bubbling process after the hot metal is discharged, the time required for the desiliconization process including the time required for bubbling can be shortened.
添付図面を参照しながら本発明を説明する。
図１は、本発明の実施状況の概要を模式的に示す説明図である。
The present invention will be described with reference to the accompanying drawings.
FIG. 1 is an explanatory diagram schematically showing the outline of the implementation status of the present invention.
図１に示すように、本発明に係る溶銑の脱珪処理方法は、高炉（図示しない）から搬送容器１に出銑した溶銑４を、搬送容器１から脱珪処理容器２に払い出す際に、添加装置３から溶銑流５に対して脱珪材である焼結鉱６を添加することにより、行う。添加された脱珪材６が溶銑流５に巻き込まれながら溶銑とともに脱珪処理容器２に落下、もしくは溶銑上に落下することによって溶銑中で攪拌され、脱珪処理が行われる。 As shown in FIG. 1, the hot metal desiliconization method according to the present invention is performed when the hot metal 4 discharged from the blast furnace (not shown) to the transfer container 1 is discharged from the transfer container 1 to the desiliconization process container 2. The addition of the sintered ore 6 as a desiliconizing material to the hot metal flow 5 from the addition device 3 is performed. The added desiliconized material 6 is agitated in the hot metal by dropping into the desiliconization processing container 2 or falling onto the hot metal while being entrained in the hot metal flow 5, and desiliconization is performed.
以下に、溶銑成分の焼結鉱６による酸化反応を説明する。
溶銑払出し温度範囲である１３００〜１５００℃では、焼結鉱中のＦｅ２Ｏ３とＦｅＯは、溶銑中ＳｉやＣと反応する。それぞれの反応は式（２）〜（５）で表され、焼結鉱と溶銑中Ｃが反応すると、式（４），（５）によりＣＯガスが生成する。式中の（ｓ）は固体状態であることを示す慣用表記であり、（ｌ）は液体状態であることを示す慣用表記であり、さらに、［Ｘ］は、当該元素Ｘが鉄中成分であることを示す慣用表記である。
Below, the oxidation reaction by the sintered ore 6 of a hot metal component is demonstrated.
In the hot metal discharge temperature range of 1300 to 1500 ° C., Fe 2 O 3 and FeO in the sintered ore react with Si and C in the hot metal. Each reaction is represented by the formulas (2) to (5). When the sintered ore and C in the molten iron react, CO gas is generated according to the formulas (4) and (5). In the formula, (s) is a conventional notation indicating that it is in a solid state, (l) is a conventional notation indicating that it is in a liquid state, and [X] is a component in iron that is the element X. It is an idiomatic notation indicating that there is.
2Fe2O3(s)+[Si] =SiO2(l) +4FeO(l) ・・・・・(2)
2FeO(s)+[Si]=SiO2(l) +2Fe(l) ・・・・・(3)
Fe2O3(s)+[C]=CO(g)+2FeO(l) ・・・・・(4)
FeO(s)+[C]=CO(g)+Fe(l) ・・・・・(5)
脱珪反応は、脱珪処理容器内で焼結鉱が溶銑と直接接触すること、もしくは脱珪スラグ中に溶解した状態の酸化鉄分と溶銑が接触することにより進行する。焼結鉱が溶銑流に巻き込まれ、溶銑と直接接触して反応が進行する場合、溶銑とよく撹拌された状態で反応が起こる。
2Fe 2 O 3 (s) + [Si] = SiO 2 (l) + 4FeO (l) (2)
2FeO (s) + [Si] = SiO 2 (l) + 2Fe (l) (3)
Fe 2 O 3 (s) + [C] = CO (g) + 2FeO (l) (4)
FeO (s) + [C] = CO (g) + Fe (l) (5)
The desiliconization reaction proceeds when the sintered ore is in direct contact with the hot metal in the desiliconization treatment vessel, or when the iron oxide component dissolved in the desiliconized slag is in contact with the hot metal. When the sinter is involved in the hot metal flow and the reaction proceeds in direct contact with the hot metal, the reaction takes place in a state well stirred with the hot metal.
溶銑中にＳｉが十分存在すれば、式（２），（３）の脱珪反応が優先して起こるため、式（４），（５）の脱炭反応が殆ど起こらずＣＯガスが発生しないため、スラグフォーミングは起こらない。 If there is sufficient Si in the hot metal, the desiliconization reaction of formulas (2) and (3) takes precedence, so the decarburization reaction of formulas (4) and (5) hardly occurs and no CO gas is generated. Therefore, slag forming does not occur.
しかし、脱珪スラグが生じた後に焼結鉱がその上に落下すると、スラグ中に焼結鉱が溶融するか、もしくはスラグ上に焼結鉱が固体のまま降り積もる状態となる。脱珪スラグ中に焼結鉱が溶解することにより生じるスラグ中のＦｅＯは、溶銑と反応して式（２）の脱珪反応を進行させるが、その反応は溶銑上に浮かんでいるスラグと溶銑の界面近傍でのみ進行するため、局所的に溶銑中Ｓｉ濃度が低下し、溶銑中Ｃとスラグ中ＦｅＯが反応する。これにより、脱珪反応効率は低下し、ＣＯガスが多量に生じるため、スラグフォーミングが助長される。 However, if the sintered ore falls on the silicon slag after the desiliconization slag is generated, the sintered ore is melted in the slag, or the sintered ore remains in a solid state on the slag. FeO in the slag generated by the dissolution of sintered ore in the desiliconized slag reacts with the hot metal to advance the desiliconization reaction of the formula (2). The reaction is the slag and hot metal floating on the hot metal. Since it proceeds only in the vicinity of the interface, the Si concentration in the hot metal locally decreases, and the hot metal C and FeO in the slag react. Thereby, the desiliconization reaction efficiency is reduced, and a large amount of CO gas is generated, so that slag forming is promoted.
これは、溶銑と焼結鉱が直接接触した場合でも、その接触時間が短く焼結鉱が溶銑上まで浮上してしまえば、同様にスラグフォーミングを生じる。また、脱珪スラグ中に焼結鉱が溶解せずにスラグ上に降り積もった場合には、スラグフォーミングは起きないものの、焼結鉱が溶銑中Ｓｉと未反応のままとなるので、脱珪反応効率が大幅に悪化してしまうと推定される。 Even if the hot metal and the sintered ore are in direct contact with each other, if the contact time is short and the sintered ore floats up to the hot metal, slag forming occurs similarly. In addition, when the sintered ore does not dissolve in the desiliconized slag, it falls on the slag, but although slag forming does not occur, the sintered ore remains unreacted with Si in the hot metal, so the desiliconization reaction It is estimated that efficiency will deteriorate significantly.
脱珪することが望ましい程度の十分なＳｉが存在する溶銑に対して、焼結鉱を接触させ続ければ、式（２），（３）の脱珪反応が優先して起こり、式（４），（５）の脱炭反応は殆ど起こらない。すなわち、脱珪反応効率が良く、スラグフォーミングが生じない、という好ましい状態が得られる。そのために、焼結鉱と溶銑の接触に関して、一定の時間を確保して、かつ、局所的な焼結鉱の添加を回避すること、さらに、脱珪に必要な量以上の焼結鉱を添加しないために、溶銑に対する焼結鉱の比率の上限を設けることも効果がある。 If the sintered ore is kept in contact with the hot metal containing sufficient Si that is desired to be desiliconized, the desiliconization reaction of formulas (2) and (3) takes place preferentially, and the formula (4) The decarburization reaction of (5) hardly occurs. That is, it is possible to obtain a preferable state in which desiliconization reaction efficiency is good and slag forming does not occur. For that purpose, it is necessary to secure a certain time for the contact between the sinter and the hot metal and to avoid the local addition of the sinter, and to add more sinter than necessary for desiliconization. Therefore, it is effective to provide an upper limit of the ratio of the sintered ore to the hot metal.
脱珪材として焼結鉱を用いる。焼結鉱は、成分の変動が少なく、自溶性であるために溶銑中Ｓｉと反応し易い。また、高炉による溶銑製造の主原料であるので、調達が比較的容易である利点もある。焼結鉱の成分は、ＣａＯ：５〜３０％，ＦｅＯとＦｅ２Ｏ３の合計：７０〜９５％であり、かつ、脱珪材中酸素体積は１４０〜１９０Ｎｌ／ｋｇである。 Sinter is used as a desiliconizing material. Sintered ore is less likely to react with Si in the hot metal because it has less component fluctuations and is self-soluble. Moreover, since it is the main raw material for hot metal production by a blast furnace, there is an advantage that procurement is relatively easy. Component of the sinter, CaO: 5 to 30% total of FeO and Fe 2 O 3: a 70% to 95%, and the oxygen volume in demineralized珪材is 140~190Nl / kg.
焼結鉱は、溶銑と速やかに脱珪反応を起こすため、払出し初期に全量投入すると脱珪処理容器中の溶銑中Ｓｉ濃度が低くなり過ぎることにより脱炭反応が優先して進行し、スラグフォーミングが起こる。逆に、処理末期に添加すると、反応時間が短いために脱珪効率が低くなり、かつスラグフォーミングが起きた場合に脱珪処理容器からスラグが溢れる可能性があるため、払出しおよび脱珪処理の中断が必要になり、脱珪処理時間が長くなってしまう。また、その際の脱珪反応効率も７０％までに完了したほうが十分な反応時間を確保できるため、脱珪反応効率は高いことが分かる。 Since sinter ore rapidly undergoes desiliconization reaction with hot metal, if the entire amount is charged at the initial stage of discharge, the decarburization reaction will proceed preferentially because the Si concentration in the hot metal in the desiliconization treatment vessel becomes too low, and slag forming will occur. Happens. Conversely, when added at the end of the treatment, the desiliconization efficiency is low due to the short reaction time, and when slag forming occurs, the slag may overflow from the desiliconization treatment vessel. An interruption is necessary, and the desiliconization processing time becomes long. In addition, it can be seen that a sufficient reaction time can be secured when the desiliconization reaction efficiency at that time is completed to 70%, so that the desiliconization reaction efficiency is high.
はじめに、スラグフォーミングによるノロ溢れの防止への脱珪材添加期間の影響を説明する。 First, the influence of the desiliconizing material addition period on the prevention of overflow due to slag forming will be described.
図２は、溶銑払い出し開始直後から脱珪材である焼結鉱の投入を開始した場合における、溶銑払出し時間に占める焼結鉱の投入継続時間と払出しの中断時間または脱珪反応効率との関係を示すグラフである。 Fig. 2 shows the relationship between the sinter ore continuation time and the discharge interruption time or desiliconization reaction efficiency in the hot metal discharge time when the injection of sintered ore as a desiliconization material is started immediately after the start of hot metal discharge It is a graph which shows.
図２のグラフに示すように、脱珪材の投入を払出し時間の７０％以前で完了すると、スラグフォーミングに起因した溶銑払出しおよび脱珪処理の中断を行う必要がなく、脱珪反応効率も高いことが分かる。 As shown in the graph of FIG. 2, when the introduction of the desiliconization material is completed before 70% of the discharge time, it is not necessary to interrupt the hot metal discharge and the desiliconization process due to slag forming, and the desiliconization reaction efficiency is also high. I understand that.
この理由は、脱珪材の投入を継続しながら溶銑払出しを行うと、脱珪処理容器内の溶銑および脱珪スラグの体積が次第に増加するので、溶銑払出し時間の後期、具体的には、溶銑払出し時間の７０％を超える期間まで脱珪材の投入を継続してしまうと、焼結鉱が脱珪反応を生ずる時間が短くなるために脱珪反応効率が悪化することに加えて、スラグフォーミングが生じた際に脱珪処理容器からスラグもしくは溶銑が溢れるおそれがあり、図２の上のグラフに示すように、溶銑払出しおよび脱珪処理の中断が大きくなってゆくためである。 The reason for this is that if the hot metal is discharged while the desiliconization material is continuously supplied, the volume of the hot metal and the desiliconized slag in the desiliconization treatment vessel will gradually increase. If the desiliconization material is continuously charged until a period exceeding 70% of the payout time, the time during which the sintered ore undergoes the desiliconization reaction is shortened, so that the desiliconization reaction efficiency is deteriorated, and slag forming is performed. This is because the slag or hot metal may overflow from the desiliconization treatment container when the slag occurs, and as shown in the upper graph of FIG.
次に、溶銑払出し速度と焼結鉱の投入速度を説明する。
図３は、焼結鉱投入速度と溶銑払出し時間に対するフォーミングの有無を示すグラフである。
Next, the hot metal discharge speed and the charging speed of the sintered ore will be described.
FIG. 3 is a graph showing the presence or absence of forming with respect to the sinter charging speed and the hot metal discharge time.
図３のグラフに示すように、上述の脱珪材投入期間内において溶銑払出し速度と脱珪材投入速度を変化させると、焼結鉱投入速度が１０００ｋｇ／ｍｉｎ以下であり、かつ、脱珪処理容器中の溶銑中Ｓｉ濃度０．２０％以上を確保すれば、スラグフォーミングが発生しないことが分かる。特に、焼結鉱中の酸素含有量等から式（１）を満たすのが好ましい。 As shown in the graph of FIG. 3, when the hot metal discharge rate and the desiliconized material charging rate are changed during the above-described desiliconized material charging period, the sintered ore charging rate is 1000 kg / min or less and the desiliconizing treatment is performed. It can be seen that slag forming does not occur if the Si concentration in the hot metal in the container is secured at 0.20% or more. In particular, the formula (1) is preferably satisfied from the oxygen content in the sintered ore and the like.
ただし、（１）式において、Ｖは脱珪材中酸素体積（Ｎｌ／ｋｇ）であり、ｖは脱珪材添加速度（ｋｇ／ｍｉｎ）であり、ｕは溶銑払出し速度（ｔ／ｍｉｎ）であり、［Ｓｉ］ｉは脱珪前溶銑中Ｓｉ濃度（質量％）（ただし，［Ｓｉ］ｉ≧０．２０％）である。脱珪材中酸素体積とは、脱珪材中に含まれるＦｅＯおよびＦｅ２Ｏ３が分解した際に発生するＯ２ガスの標準状態での体積を、脱珪材単位質量当たりで表す。 However, in the formula (1), V is the oxygen volume in the desiliconized material (Nl / kg), v is the desiliconized material addition rate (kg / min), and u is the hot metal discharge rate (t / min). Yes, [Si] i is the Si concentration (mass%) in the hot metal before desiliconization (where [Si] i ≧ 0.20%). The oxygen volume in the desiliconized material represents the volume in a standard state of O 2 gas generated when FeO and Fe 2 O 3 contained in the desiliconized material are decomposed per unit mass of the desiliconized material.
最後に、脱珪処理時に添加する焼結鉱の粒径を説明する。
溶銑を搬送容器から脱珪処理容器へ払い出す際に、払い出し開始直後から脱珪材の添加を開始し、上記の条件を満たした上で焼結鉱の平均粒径を変化させて脱珪処理を行った結果、焼結鉱の粒径が小さ過ぎるとスラグフォーミングが発生する上、脱珪反応効率は低くなり、焼結鉱の平均粒径の増加に伴って脱珪反応効率が向上し、ある所定の平均粒径を境に脱珪反応効率が低下する。すなわち、焼結鉱の平均粒径により脱珪効果が変化し、また、脱珪反応効率が最大となる焼結鉱の平均粒径の最適範囲が存在する。焼結鉱の平均粒径の最適範囲は５〜１０ｍｍである。
Finally, the particle size of the sintered ore added during the desiliconization process will be described.
When the hot metal is discharged from the transfer container to the desiliconization processing container, the addition of the desiliconizing material is started immediately after the start of the discharge, and after satisfying the above conditions, the average particle size of the sintered ore is changed to perform the desiliconization process. As a result, when the particle size of the sintered ore is too small, slag forming occurs, and the desiliconization reaction efficiency decreases, and the desiliconization reaction efficiency improves as the average particle size of the sintered ore increases, Desiliconization reaction efficiency decreases at a certain predetermined average particle diameter. That is, the desiliconization effect varies depending on the average particle size of the sintered ore, and there is an optimum range of the average particle size of the sintered ore in which the desiliconization reaction efficiency is maximized. The optimum range of the average particle size of the sintered ore is 5 to 10 mm.
焼結鉱の平均粒径が５ｍｍ未満であると、脱珪スラグ上に浮遊して溶銑との反応に寄与できない割合が増えたり、焼結鉱が生成した脱珪スラグに捕捉されるために溶銑と脱珪スラグの界面付近において、局所的に式（２），（３）のみならず、式（４），（５）の反応を併発してスラグフォーミングが発生するためである。一方、焼結鉱の平均粒径が１０ｍｍ超であると、溶銑との反応界面積が小さくなる。 If the average particle size of the sinter is less than 5 mm, the ratio of floating on the desiliconized slag and not contributing to the reaction with the hot metal increases, or the hot metal is trapped by the desiliconized slag generated by the sintered ore. This is because, in the vicinity of the interface between the silicon slag and the desiliconized slag, not only the expressions (2) and (3) but also the reactions of the expressions (4) and (5) are locally generated. On the other hand, when the average particle size of the sintered ore is more than 10 mm, the reaction interface area with the hot metal becomes small.
従来の技術では、脱珪材として焼結鉱を使用する場合の平均粒径は４〜５ｍｍ以下であることが多かった。これは、すでに述べたように、焼結鉱と溶銑の反応を早く進めること、および、通常は高炉に装入されない細かい粒径である焼結鉱を有効利用できることという観点から使用されてきたと考えられる。 In the prior art, the average particle size in the case of using sintered ore as a desiliconizing material is often 4 to 5 mm or less. As already mentioned, this is considered to have been used from the viewpoint of advancing the reaction between the sinter and hot metal quickly and the effective utilization of the sinter having a fine particle size that is not normally charged into the blast furnace. It is done.
この結果を従来の技術と同様にガスバブリングを実施した結果と比較すると、ガスバブリング実施時と遜色ない脱珪反応効率が得られる。 When this result is compared with the result of carrying out gas bubbling in the same manner as in the prior art, desiliconization reaction efficiency comparable to that at the time of gas bubbling can be obtained.
本発明を、実施例を参照しながらより具体的に説明する。
高炉から搬送容器である混銑車に出銑された溶銑２８０〜３３０ｔを脱珪処理容器である取鍋に払出す際に、溶銑流に対して焼結鉱を添加して脱珪処理を実施した。溶銑の成分は、［Ｃ］：４．２〜４．８％，［Ｓｉ］：０．４０〜０．５０％であり、払出し後温度は１３８０〜１４３０℃であった。
The present invention will be described more specifically with reference to examples.
When the hot metal 280 to 330 t discharged from the blast furnace to the kneading vehicle as the transport container was discharged to the ladle as the desiliconization treatment container, the demineralization treatment was performed by adding sintered ore to the molten iron flow. . The hot metal components were [C]: 4.2 to 4.8%, [Si]: 0.40 to 0.50%, and the temperature after dispensing was 1380 to 1430 ° C.
実施例で使用した焼結鉱は表１に示した成分のものを用いた。脱珪材中酸素体積は１６１（Ｎｌ／ｋｇ）である。したがって、本実施例において、脱珪材添加速度の上限は９９４（ｋｇ／ｍｉｎ）である。焼結鉱の平均粒径は、レーザー回折・散乱法によって求めた粒度分布における積算値５０％での粒径を意味する。 The sintered ore used in the examples used the components shown in Table 1. The oxygen volume in the desiliconized material is 161 (Nl / kg). Therefore, in this example, the upper limit of the desiliconization material addition rate is 994 (kg / min). The average particle size of the sintered ore means the particle size at an integrated value of 50% in the particle size distribution obtained by the laser diffraction / scattering method.
表２に脱珪処理条件および処理の結果をまとめて示す。 Table 2 summarizes the desiliconization treatment conditions and the treatment results.
従来例１〜５は、払出し後にガスバブリングを実施する操業条件の従来例であって、焼結鉱の添加期間は０〜３２％であり、焼結鉱の添加速度が本発明の範囲外である１２００ｋｇ／ｍｉｎと速く、脱珪処理中の容器内溶銑中Ｓｉ濃度は０．０７〜０．１２％であるものの、全ての従来例１〜５においてスラグフォーミングが発生した。焼結鉱の平均粒径は２〜４ｍｍでは８０％以上の高い脱珪反応効率が得られているが、それ以外の範囲では７０％以下となっている。 Conventional Examples 1 to 5 are conventional examples of operating conditions for carrying out gas bubbling after dispensing, and the addition period of sintered ore is 0 to 32%, and the addition rate of sintered ore is outside the scope of the present invention. Although it was as fast as 1200 kg / min and the Si concentration in the molten iron in the container during the desiliconization treatment was 0.07 to 0.12%, slag foaming occurred in all the conventional examples 1 to 5. The average particle size of the sintered ore has a high desiliconization reaction efficiency of 80% or more at 2 to 4 mm, but it is 70% or less in other ranges.
比較例１，２は、それぞれ、焼結鉱の平均粒径を、本発明の範囲外である３ｍｍ，１５ｍｍとした例である。脱珪反応効率は６０％以下と低位であり、スラグフォーミングも発生した。平均粒径が大きい焼結鉱は、反応時間が長いため、焼結鉱の大部分が脱珪反応に寄与する前にスラグ中に浮上し、脱珪スラグに取り込まれる。スラグに取り込まれた焼結鉱は、スラグ／溶銑界面でのみ脱珪反応を起こすため、局所的にＳｉ濃度の低くなった溶銑が脱炭反応を起こし、フォーミングが発生し易くなるためである。 Comparative Examples 1 and 2 are examples in which the average particle size of the sintered ore is 3 mm and 15 mm, which are outside the scope of the present invention. The desiliconization reaction efficiency was as low as 60% or less, and slag forming also occurred. Since the sinter with a large average particle size has a long reaction time, most of the sinter floats in the slag before contributing to the desiliconization reaction, and is taken into the desiliconization slag. This is because the sintered ore taken into the slag undergoes a desiliconization reaction only at the slag / hot metal interface, so that the hot metal having a locally low Si concentration undergoes a decarburization reaction and forms easily.
比較例３，４は、焼結鉱の平均粒径を６ｍｍとしたものの、焼結鉱の添加速度が本発明の範囲を逸脱した例である。比較例３は、溶銑払出し速度ｕが小さい（溶銑払出し時間が長い）ため、式（１）の右辺が小さくなったにも関わらず、焼結鉱の添加速度を式（１）右辺の値以上に大きくした例であり、比較例４は焼結鉱の添加速度を１２００ｋｇ／分とした例であり、式（１）の右辺の値よりは小さいものの、１６０００／Ｖ（＝９９４）よりも大きく本発明の範囲を外れたものである。比較例３，４は、そのどちらも、脱珪反応効率は低位であり、スラグフォーミングも発生した。 In Comparative Examples 3 and 4, although the average particle size of the sintered ore was 6 mm, the addition rate of the sintered ore deviated from the scope of the present invention. In Comparative Example 3, since the hot metal discharge speed u is low (the hot metal discharge time is long), the addition rate of the sintered ore is equal to or higher than the value on the right side of the formula (1) even though the right side of the formula (1) is small. Comparative Example 4 is an example in which the addition rate of the sintered ore is 1200 kg / min, which is smaller than the value on the right side of the formula (1) but larger than 16000 / V (= 994). This is outside the scope of the present invention. In both Comparative Examples 3 and 4, the desiliconization reaction efficiency was low, and slag foaming also occurred.
比較例５は、焼結鉱の平均粒径を６ｍｍに調整し、焼結鉱の添加速度を５００ｋｇ／分、かつ、式（１）の右辺の値以下とした上で、焼結鉱の添加量が１１．２ｋｇ／溶銑ｔと本発明の範囲を外れた例である。比較例５では、溶銑に対する焼結鉱の比率の上限を超えたため、脱珪処理末期にスラグフォーミングが発生した。また、脱珪反応効率は７３％と比較例１〜４と比較すると高位となったものの、従来例２，３と比較すると低位であった。 In Comparative Example 5, the average particle size of the sintered ore was adjusted to 6 mm, the addition rate of the sintered ore was set to 500 kg / min, and not more than the value on the right side of the formula (1). This is an example in which the amount is 11.2 kg / molten iron t and out of the scope of the present invention. In Comparative Example 5, since the upper limit of the ratio of sintered ore to hot metal was exceeded, slag foaming occurred at the end of the desiliconization process. Further, the desiliconization reaction efficiency was 73%, which was higher than that of Comparative Examples 1 to 4, but was lower than that of Conventional Examples 2 and 3.
これに対し、本発明例のＮｏ．１−１〜１−３は、いずれも、焼結鉱の平均粒径を５〜１０ｍｍに調整し、焼結鉱の添加速度は５００ｋｇ／分、かつ、式（１）右辺の値以下とした上で、払出し完了後にガスバブリングを実施した例である。いずれの本発明例のＮｏ．１−１〜１−３もスラグフォーミングは発生せず、脱珪反応効率は８０％以上であった。 In contrast, No. of the present invention example. In 1-1 to 1-3, the average particle size of the sintered ore was adjusted to 5 to 10 mm, the addition rate of the sintered ore was 500 kg / min, and the value on the right side of the formula (1) was not more than the value. In the above example, gas bubbling is performed after the completion of the dispensing. No. of any of the inventive examples. No slag forming occurred in 1-1 to 1-3, and the desiliconization reaction efficiency was 80% or more.
本発明例Ｎｏ．１−４は、本発明例のＮｏ．１−１〜１−３と同条件で、ガスバブリングを実施しなかった例であるが、同様にスラグフォーミングは発生せず、バブリングを実施していないにもかかわらず、脱珪反応効率は７３％と比較例１のいずれの結果と比較しても高位であった。 Invention Example No. 1-4 is the No. of the example of the present invention. In this example, gas bubbling was not performed under the same conditions as 1-1 to 1-3. Similarly, slag foaming did not occur, and the desiliconization reaction efficiency was 73 even though bubbling was not performed. % And the results of Comparative Example 1 were high.
さらに、本発明例のＮｏ．２−１〜２−３は、本発明例Ｎｏ．１−１〜１−３の条件に加え、バブリングを実施せず、かつ、焼結鉱の添加期間を払出し時間に占める７０％までに完了した例である。脱珪反応効率は、全て８０％以上となり、バブリングを実施した従来例とほぼ同等の脱珪反応効率が得られ、かつ、スラグフォーミングも発生しないという良好な結果が得られた。 Furthermore, No. of this invention example. 2-1 to 2-3 are examples of the present invention. In addition to the conditions of 1-1 to 1-3, bubbling is not performed, and the addition period of the sintered ore is completed to 70% of the payout time. The desiliconization reaction efficiency was 80% or more in all cases, and the desiliconization reaction efficiency almost equivalent to that of the conventional example in which bubbling was performed was obtained, and good results were obtained that no slag forming occurred.
これらの結果から、高炉から出銑した溶銑を、搬送容器から脱珪処理容器に払い出す際の溶銑流に対して脱珪材を添加することにより溶銑を脱珪処理する際に、脱珪材の平均粒径と焼結鉱の添加速度を本発明で規定する所定の範囲に制御することにより、スラグフォーミングが安定的に抑制でき、脱珪反応効率も向上すること、さらには、焼結鉱の添加後にガスバブリングによる撹拌を実施しなくても脱珪材反応効率の向上が可能となることが、いずれも確認された。 From these results, when the hot metal discharged from the blast furnace is desiliconized by adding the desiliconized material to the hot metal flow when it is discharged from the transfer container to the desiliconized processing container, By controlling the average particle size of sinter and the addition rate of the sinter within the predetermined range defined in the present invention, slag forming can be stably suppressed, the desiliconization reaction efficiency can be improved, It was confirmed that it is possible to improve the desiliconization reaction efficiency without performing stirring by gas bubbling after the addition of.
１ 搬送容器
２ 脱珪処理容器
３ 添加装置
４ 溶銑
５ 溶銑流
６ 焼結鉱
DESCRIPTION OF SYMBOLS 1 Transfer container 2 Desiliconization processing container 3 Addition apparatus 4 Hot metal 5 Hot metal flow 6 Sinter
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| JPS5792116A (en) * | 1980-11-28 | 1982-06-08 | Nippon Kokan Kk <Nkk> | Continuous desiliconization method for molten iron |
| US4388112A (en) * | 1980-03-21 | 1983-06-14 | Nippon Steel Corporation | Steelmaking process with separate refining steps |
| JPH11269526A (en) * | 1998-03-20 | 1999-10-05 | Sumitomo Metal Ind Ltd | Desiliconization of molten iron by addition of desiliconizing agent |
| JPH11269525A (en) * | 1998-03-20 | 1999-10-05 | Sumitomo Metal Ind Ltd | Desiliconization of molten iron by addition of desiliconizing agent |
| JP2000282123A (en) * | 1999-03-31 | 2000-10-10 | Sumitomo Metal Ind Ltd | Method for desiliconizing molten iron |
| JP2000290715A (en) * | 1999-04-06 | 2000-10-17 | Sumitomo Metal Ind Ltd | Method for desiliconizing molten iron |
| JP2001040410A (en) * | 1999-07-26 | 2001-02-13 | Sumitomo Metal Ind Ltd | Method for desiliconizing molten iron |
| JP2007224388A (en) * | 2006-02-24 | 2007-09-06 | Sumitomo Metal Ind Ltd | Method for treating molten iron |
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|---|---|---|---|---|
| US4388112A (en) * | 1980-03-21 | 1983-06-14 | Nippon Steel Corporation | Steelmaking process with separate refining steps |
| JPS5792116A (en) * | 1980-11-28 | 1982-06-08 | Nippon Kokan Kk <Nkk> | Continuous desiliconization method for molten iron |
| JPH11269526A (en) * | 1998-03-20 | 1999-10-05 | Sumitomo Metal Ind Ltd | Desiliconization of molten iron by addition of desiliconizing agent |
| JPH11269525A (en) * | 1998-03-20 | 1999-10-05 | Sumitomo Metal Ind Ltd | Desiliconization of molten iron by addition of desiliconizing agent |
| JP2000282123A (en) * | 1999-03-31 | 2000-10-10 | Sumitomo Metal Ind Ltd | Method for desiliconizing molten iron |
| JP2000290715A (en) * | 1999-04-06 | 2000-10-17 | Sumitomo Metal Ind Ltd | Method for desiliconizing molten iron |
| JP2001040410A (en) * | 1999-07-26 | 2001-02-13 | Sumitomo Metal Ind Ltd | Method for desiliconizing molten iron |
| JP2007224388A (en) * | 2006-02-24 | 2007-09-06 | Sumitomo Metal Ind Ltd | Method for treating molten iron |
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