JP3574690B2 - Hot metal desulfurization method - Google Patents
Hot metal desulfurization method Download PDFInfo
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- JP3574690B2 JP3574690B2 JP32614494A JP32614494A JP3574690B2 JP 3574690 B2 JP3574690 B2 JP 3574690B2 JP 32614494 A JP32614494 A JP 32614494A JP 32614494 A JP32614494 A JP 32614494A JP 3574690 B2 JP3574690 B2 JP 3574690B2
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- Prior art keywords
- hot metal
- slag
- desulfurization
- weight
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- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
Description
【０００１】
【産業上の利用分野】
本発明は、溶銑の脱硫方法に関する。
【０００２】
【従来技術】
溶銑の脱硫剤としては、例えば日本金属学会会報第２２巻第５号（１９８３年）に報告されているように、ＣａＯを主成分とし、これにＣａＣＯ３ 等の反応促進剤を１０〜３５重量％及びＣａＦ２ 等の滓化促進剤を３〜５重量％混合したものが一般に用いられている。脱硫剤中の反応促進剤が少ないと脱硫効率が低下し、多過ぎるとスロッピングが激しくなる。また滓化促進剤が少ないと、滓化不十分のため脱硫効率が低下し、多いと耐火物の溶損が激しくなる。
【０００３】
こうした脱硫剤を用いて、脱珪及び脱燐を施しておらず、しかも高炉スラグが存在した状態の溶銑を脱硫した場合、形成されるスラグは塊状かつ固体状をなすため、スラグドラッカー等の設備を用いることなく、トピードカー或いは脱硫鍋等の反応容器の傾動による自然排滓が可能となり、工場の自動化及び無人化を推進することができる。
【０００４】
一方、最近脱硫時間の短縮、或いは脱硫時のスロッピング軽減等を目的として、優れた脱硫能を有する金属Ｍｇが注目されている。特に、粉体状に加工した後、その表面をスラグ質でコーティングする技術の向上や、消防法の改正により保管時の条件が緩和されたことも合わせて、ＣａＯと共に吹込むことにより脱硫剤として工業的に用いられるようになってきている。こうした技術が例えば、特開平５−１４０６２６号公報に開示されている。この場合、Ｍｇの配合は２０〜９５重量％となっているが、これは、脱硫前の脱燐後に除滓を行う場合であり、高炉スラグが存在する場合には、ある程度ＣａＯにより、脱硫前のスラグの塩基度を高くして脱硫効率を高める必要がある。
【０００５】
【発明が解決しようとする課題】
上述するようなＭｇを配合した脱硫剤を用いた場合、溶銑中に溶存或いは一度気化したＭｇが酸化して生成したＭｇＯのために、局部的に融点が上昇し、塊状スラグと共に粉体状スラグが形成される割合が増加してくる。粉体状のスラグは、反応容器の傾動による排滓を実施した場合、十分に除去することができず、溶銑と共に転炉に持ち込まれて、酸素吹き吹錬中に、
（ＣａＳ）＋Ｏ２ →ＣａＯ＋［Ｓ］
の反応により、溶銑中に硫黄が戻り復硫する原因となる。
【０００６】
こうした転炉での復硫を防止するために、必要以上に排滓処理を施した場合、粉体状のスラグは除去されるが、同時に余分の溶銑が脱硫スラグ中へ流出されることになり、鉄分のロスが増加するという問題が生ずる。
これらの問題点を解決するために、スラグドラッカーを用いて排滓することも考えられるが、この場合、ドラッカー設備及び運転要員が必要となり、このようなスラグ除去作業は、工場の自動化及び無人化を妨げる要因となる。
【０００７】
本発明は、ＣａＯ−Ｍｇ脱硫剤を用いたときの、転炉での復硫或いは鉄分ロスの増加の問題を発生させることなく、トピードカーや脱硫鍋の傾動による自然排滓を可能にする溶銑脱硫剤を用いた溶銑脱硫方法を提供することを目的としている。
【０００８】
【課題の解決手段】
本発明は、上記の課題を解決するために脱珪、脱燐を施しておらず、しかも高炉スラグが存在する溶銑にスラグを塊状化させて自然排滓を可能とするために金属Ｍｇ５〜３０重量％、ＣａＯ９５〜６０重量％の範囲の組成物を重量割合で９０％以上含有したものに、更にＣａＦ2 を３〜１０重量％配合した粉体状の溶銑脱硫剤を吹込むことにより脱硫する溶銑の脱硫方法を提供しようとするものである。
【０００９】
ＣａＯ−Ｍｇの組成物にＣａＦ２ を適量混合することで、局部的に脱硫スラグの融点が低下し、溶融後に凝固或いは焼結させることができるようになる。このため形成されるスラグは塊状となり、粉体状のスラグの割合は激減した。
本発明において、Ｍｇの配合割合を５〜３０重量％としたのは、５重量％未満では、脱硫効率が悪くなり、３０重量％を越えると、ＣａＯの割合が減少し、脱硫スラグの塩基度が小さくなるため、脱硫効率が低下するためである。また、ＣａＦ２ の含有量を３〜１０重量％としたのは、３重量％未満では、粉体状スラグの割合が増加し、１０重量％を越えると、脱硫剤中のＭｇ含有量の減少により脱硫能の低下、或いはＣａＦ２ の影響により耐火物の損耗が激しくなるためである。
【００１０】
【実施例】
脱硫鍋において、実施例及び比較例の脱硫剤を溶銑中に、搬送ガスと共に浸漬ランスの先端から吹込むことにより試験を行った。溶銑には、脱珪、脱燐を施しておらず、しかも高炉スラグが存在したものを用いた。なお、脱硫後のスラグは、脱硫鍋を傾動させることによってスラグ鍋に排出させた。主な試験条件を以下に示す。
【００１１】
溶銑量 ： １８０〜２００ｔ
溶銑温度 ： １２８０〜１３２０℃
脱硫剤吹込速度 ： ８０〜１００ｋｇ／ｍｉｎ
脱硫剤原単位 ： ２．５〜３．０ｋｇ／ｔ
搬送ガス ： Ｎ２
搬送ガス量 ： １．０Ｎｍ３／ｍｉｎ
脱硫剤の組成を変化させて実施した試験結果を表１に示す。表中、転炉での復硫量は次式で定義し、０．００３ ％未満の場合を〇、０．００３ ％以上の場合を×とした。
【００１２】
復硫量＝［Ｓ］Ｅｐ−［Ｓ］ｆ
［Ｓ］Ｅｐ：転炉吹止め後の溶鋼中のＳ濃度（％）
［Ｓ］ｆ ：脱硫処理後の溶銑中のＳ濃度 （％）
また、鉄分ロス量は５ｋｇ／ｔ未満の場合を〇、５ｋｇ／ｔ以上の場合を×とし、自然排滓の評価は、復硫量及び鉄分ロス量の評価が両方〇の場合を〇、どちらか一方、或いは両方×の場合を×とした。併せて、脱硫率は次式で定義し、６０％以上のものを〇、６０％未満のものを×とした。
【００１３】
脱硫率＝｛（［Ｓ］ｉ−［Ｓ］ｆ）／［Ｓ］ｉ｝×１００（％）
［Ｓ］ｉ：脱硫処理前の溶銑中のＳ濃度（％）
なお、総合評価は、自然排滓と脱硫率の評価が両方〇の場合を〇、どちらか一方、或いは両方×の場合を×とした。
【００１４】
【表１】
試験結果から、実施例ではいずれも、復硫量及び鉄分ロス量それぞれ０．００３ ％未満及び５ｋｇ／ｔ未満であり、自然排滓可能で、しかも脱硫率は６０％以上であった。一方、本発明範囲外の組成をもつ比較例の脱硫剤では、自然排滓ができなかったか、脱硫率が６０％未満であったか、或いはその両方であった。
【００１６】
【発明の効果】
本発明によれば、脱珪、脱燐を施しておらず、しかも高炉スラグが存在する溶銑に対して、高脱硫効率で、かつ復硫及び鉄分ロスを増加させることなく自然排滓が可能な脱硫処理ができるようになる。また、排滓のためのドラッカー設備とその運転要員が不要となり、工場の自動化及び無人化が可能となる。[0001]
[Industrial applications]
The present invention relates to a method for desulfurizing hot metal.
[0002]
[Prior art]
As the desulfurizing agent for hot metal, for example, as reported in the Japan Institute of Metals Vol.22, No.5 (1983), CaO is used as a main component, and a reaction accelerator such as CaCO 3 is added in an amount of 10 to 35% by weight. % And a mixture of 3% to 5% by weight of a slagging accelerator such as CaF 2 are generally used. If the amount of the reaction accelerator in the desulfurizing agent is small, the desulfurization efficiency is reduced, and if the amount is too large, slopping becomes severe. When the amount of the slag formation accelerator is small, desulfurization efficiency is reduced due to insufficient slag formation, and when the amount is large, erosion of the refractory becomes severe.
[0003]
When desiliconization and dephosphorization are not performed using such a desulfurizing agent and the hot metal in the presence of blast furnace slag is desulfurized, the slag formed is in a lump and solid state. Without the use of, the waste can be spontaneously discharged by tilting a reaction vessel such as a topped car or a desulfurization pot, and the automation and unmanned factory can be promoted.
[0004]
On the other hand, recently, metallic Mg having excellent desulfurization ability has been attracting attention for the purpose of shortening the desulfurization time or reducing slopping during desulfurization. In particular, after processing into powder, the surface is coated with slag, and the conditions for storage have been eased due to the revision of the Fire Service Law. It is being used industrially. Such a technique is disclosed in, for example, JP-A-5-140626. In this case, the content of Mg is 20 to 95% by weight, but this is a case in which slag is removed after dephosphorization before desulfurization. The desulfurization efficiency must be increased by increasing the basicity of the slag.
[0005]
[Problems to be solved by the invention]
When a desulfurizing agent containing Mg as described above is used, the melting point locally rises due to MgO generated by oxidation of Mg dissolved or once vaporized in the hot metal, and powdered slag is added together with massive slag. The rate at which is formed increases. The powdery slag cannot be sufficiently removed when the sludge of the reaction vessel is tilted, and is taken into the converter together with the hot metal.
(CaS) + O 2 → CaO + [S]
This causes the sulfur to return to the hot metal and cause resulfurization.
[0006]
If waste treatment is performed more than necessary to prevent such resulfurization in the converter, powdery slag is removed, but at the same time, excess hot metal flows out into the desulfurization slag. This causes a problem that iron loss increases.
In order to solve these problems, it is conceivable that the waste is discharged using a slag draker.In this case, however, drakker equipment and operation personnel are required, and such slag removal work is automated and unmanned in factories. Is a factor that hinders
[0007]
The present invention provides a hot metal desulfurization method that enables natural discharge by tilting a topped car or desulfurization pot without using a CaO-Mg desulfurizing agent and without causing a problem of resulfurization in a converter or an increase in iron loss. It is an object of the present invention to provide a hot metal desulfurization method using an agent.
[0008]
[Means for solving the problem]
The present invention does not carry out desiliconization and dephosphorization in order to solve the above-mentioned problem, and furthermore, in order to allow slag to be agglomerated in molten iron in which blast furnace slag is present and to enable natural discharge , metal Mg5 to 30 are used. wt%, the one containing more than 90% in a weight ratio of the composition in the range of CaO95~60 wt%, desulfurization by writing further blown to the CaF 2 3 to 10% by weight compounded powdery hot metal desulfurizing agent An object of the present invention is to provide a method for desulfurizing hot metal.
[0009]
By mixing an appropriate amount of CaF 2 with the CaO—Mg composition, the melting point of the desulfurized slag is locally reduced, and the slag can be solidified or sintered after melting. As a result, the formed slag became lump, and the ratio of the powdery slag was drastically reduced.
In the present invention, the mixing ratio of Mg is set to 5 to 30% by weight. If it is less than 5% by weight, the desulfurization efficiency is deteriorated, and if it exceeds 30% by weight, the proportion of CaO decreases, and the basicity of the desulfurized slag is reduced. Is reduced, and the desulfurization efficiency is reduced. Further, the content of CaF 2 is set to 3 to 10% by weight. When the content is less than 3% by weight, the ratio of powdery slag increases, and when it exceeds 10% by weight, the Mg content in the desulfurizing agent decreases. This is because the desulfurization ability is reduced, or the refractories are greatly worn by the influence of CaF 2 .
[0010]
【Example】
In a desulfurization pot, the test was performed by blowing the desulfurizing agents of Examples and Comparative Examples into the hot metal together with a carrier gas from the tip of an immersion lance. The hot metal used had not been desiliconized or dephosphorized and had blast furnace slag. The desulfurized slag was discharged into the slag pot by tilting the desulfurization pot. The main test conditions are shown below.
[0011]
Hot metal: 180-200t
Hot metal temperature: 1280-1320 ° C
Desulfurizing agent blowing speed: 80 to 100 kg / min
Desulfurizer basic unit: 2.5 to 3.0 kg / t
Carrier gas: N 2
Carrier gas amount: 1.0 Nm 3 / min
Table 1 shows the results of tests performed by changing the composition of the desulfurizing agent. In the table, the amount of resulfurization in the converter is defined by the following formula, where Δ is less than 0.003% and X is 0.003% or more.
[0012]
Desulfurization amount = [S] Ep-[S] f
[S] Ep: S concentration (%) in molten steel after blowing off the converter
[S] f: S concentration in hot metal after desulfurization treatment (%)
In addition, iron loss is less than 5 kg / t, x is 5 kg / t or more, and natural waste is evaluated. If both resulfurization and iron loss are evaluated as 〇, One or both of the cases of x were evaluated as x. At the same time, the desulfurization rate was defined by the following equation.
[0013]
Desulfurization rate = {([S] i- [S] f) / [S] i} × 100 (%)
[S] i: S concentration (%) in hot metal before desulfurization treatment
In addition, the comprehensive evaluation was evaluated as 〇 when both the natural waste and the desulfurization rate were evaluated as 〇, and as × when either or both ×.
[0014]
[Table 1]
From the test results, in each of the examples, the resulfurization amount and the iron loss amount were less than 0.003% and less than 5 kg / t, respectively. On the other hand, in the desulfurizing agent of the comparative example having a composition outside the range of the present invention, the natural waste could not be discharged, the desulfurization rate was less than 60%, or both.
[0016]
【The invention's effect】
According to the present invention, desiliconization and dephosphorization have not been performed, and natural slag can be discharged to hot metal having blast furnace slag with high desulfurization efficiency and without increasing resulfurization and iron loss. Desulfurization treatment can be performed. In addition, a drakker facility for drainage and its operating personnel are not required, so that the factory can be automated and unmanned.
Claims (1)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP32614494A JP3574690B2 (en) | 1994-12-27 | 1994-12-27 | Hot metal desulfurization method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP32614494A JP3574690B2 (en) | 1994-12-27 | 1994-12-27 | Hot metal desulfurization method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH08176632A JPH08176632A (en) | 1996-07-09 |
| JP3574690B2 true JP3574690B2 (en) | 2004-10-06 |
Family
ID=18184549
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP32614494A Expired - Lifetime JP3574690B2 (en) | 1994-12-27 | 1994-12-27 | Hot metal desulfurization method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3574690B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100448626B1 (en) * | 2000-08-08 | 2004-09-13 | 주식회사 포스코 | Desulphurizer for iron hot metal using iron-making slag |
| CN106929624A (en) * | 2017-04-01 | 2017-07-07 | 首钢总公司 | A kind of compound fritting iron melt desulfurizing agent and its preparation and application |
-
1994
- 1994-12-27 JP JP32614494A patent/JP3574690B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH08176632A (en) | 1996-07-09 |
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