JP2017031437A5 - - Google Patents
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- JP2017031437A5 JP2017031437A5 JP2015148939A JP2015148939A JP2017031437A5 JP 2017031437 A5 JP2017031437 A5 JP 2017031437A5 JP 2015148939 A JP2015148939 A JP 2015148939A JP 2015148939 A JP2015148939 A JP 2015148939A JP 2017031437 A5 JP2017031437 A5 JP 2017031437A5
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- desulfurization
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- 230000003009 desulfurizing Effects 0.000 description 61
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium monoxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 56
- 238000006477 desulfuration reaction Methods 0.000 description 48
- 229910052751 metal Inorganic materials 0.000 description 35
- 239000002184 metal Substances 0.000 description 35
- 235000012255 calcium oxide Nutrition 0.000 description 28
- 239000000292 calcium oxide Substances 0.000 description 28
- 239000003795 chemical substances by application Substances 0.000 description 25
- 238000006243 chemical reaction Methods 0.000 description 12
- WUKWITHWXAAZEY-UHFFFAOYSA-L Calcium fluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 11
- 239000010436 fluorite Substances 0.000 description 11
- CDBYLPFSWZWCQE-UHFFFAOYSA-L sodium carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 9
- 229910004298 SiO 2 Inorganic materials 0.000 description 8
- 229910052782 aluminium Inorganic materials 0.000 description 7
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminum Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 7
- 238000002347 injection Methods 0.000 description 5
- 239000007924 injection Substances 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 229910052760 oxygen Inorganic materials 0.000 description 5
- 239000001301 oxygen Substances 0.000 description 5
- MYMOFIZGZYHOMD-UHFFFAOYSA-N oxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 5
- 235000017550 sodium carbonate Nutrition 0.000 description 5
- 229910000029 sodium carbonate Inorganic materials 0.000 description 5
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 4
- 235000015450 Tilia cordata Nutrition 0.000 description 4
- 235000011941 Tilia x europaea Nutrition 0.000 description 4
- 239000004571 lime Substances 0.000 description 4
- 239000003638 reducing agent Substances 0.000 description 4
- 239000012159 carrier gas Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 238000007664 blowing Methods 0.000 description 2
- 239000002893 slag Substances 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 241001088417 Ammodytes americanus Species 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 230000002542 deteriorative Effects 0.000 description 1
- 238000005755 formation reaction Methods 0.000 description 1
- 230000012447 hatching Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000012254 powdered material Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
- -1 what has carbide Substances 0.000 description 1
Description
本発明は、キャリアガスを使って粉状の脱硫剤を直接溶銑中に吹き込む溶銑脱硫(以下、インジェクション脱硫と言う)に関するものである。 The present invention relates to hot metal desulfurization (hereinafter referred to as injection desulfurization) in which a powdered desulfurizing agent is blown directly into hot metal using a carrier gas.
従来、溶銑用の脱硫剤としては、カーバイド、ソーダ灰、生石灰を主成分とするものが提案されてきた。このうち、カーバイドは高価であり、ソーダ灰は、溶銑の温度の低下が大きいことや処理後のスラグ(Na2O)が高くなり、セメント原料や路盤材への有効利用が困難となることから生石灰系の脱硫剤が主流となっている。 Conventionally, as a desulfurization agent for hot metal, what has carbide, soda ash, and quicklime as a main component has been proposed. Of these, carbide is expensive, soda ash has a large decrease in hot metal temperature, and slag (Na 2 O) after treatment becomes high, making it difficult to effectively use it as a cement raw material and roadbed material. Quicklime-based desulfurization agents are the mainstream.
生石灰による脱硫は、下記の式(1)で示す反応である。
CaO+[S]=CaS+[O] ・・・(1)
ここで、[S]は溶銑中の硫黄、[O]は溶銑中の酸素をあらわす。
生石灰は、溶銑温度にて固体であり反応速度が遅く、短時間では十分な脱硫が行なわれない。そのため、生石灰での脱硫は溶銑との反応界面積を増やすことが重要であり、粉状のものを溶銑中にキャリアガスと共に吹込む方法や石灰を上置きして機械的に攪拌を行う方法などが一般的に知られている。
Desulfurization with quicklime is a reaction represented by the following formula (1).
CaO + [S] = CaS + [O] (1)
Here, [S] represents sulfur in the hot metal, and [O] represents oxygen in the hot metal.
Quick lime is a solid at the hot metal temperature and has a slow reaction rate, and sufficient desulfurization is not performed in a short time. Therefore, desulfurization with quick lime is important to increase the reaction interfacial area with hot metal, such as a method of blowing a powdered material with a carrier gas into the hot metal, a method of mechanically stirring lime on top, etc. Is generally known.
また、式の(1)反応は溶銑中酸素が低い程、平衡が右に移動するため脱硫率があがる。通常、高炉から払い出された溶銑は、0.30〜1.0質量%のSiを含んでおり、下記の式(2)の反応により、式(1)で酸素が生成しても、溶銑中酸素ポテンシャルは低く保たれる。
[Si]+2[O] =SiO2 ・・・(2)
ここで、[Si]は溶銑中の珪素をあらわす。
しかしながら、式(2)にて生じたSiO2は、CaO表面に2CaO・SiO2を生成し、CaOが[S]と反応するのを妨げ、未反応CaOが多くなり脱硫率が悪化するため、[Si]濃度は低いことが好ましいことが知られている。
Further, in the reaction (1) of the formula, the lower the oxygen in the hot metal, the higher the desulfurization rate because the equilibrium moves to the right. Usually, the hot metal discharged from the blast furnace contains 0.30 to 1.0% by mass of Si, and even if oxygen is generated in the formula (1) by the reaction of the following formula (2), Medium oxygen potential is kept low.
[Si] +2 [O] = SiO 2 (2)
Here, [Si] represents silicon in the hot metal.
However, the SiO 2 generated in the formula (2) generates 2CaO · SiO 2 on the CaO surface, prevents CaO from reacting with [S], and increases the amount of unreacted CaO, thereby deteriorating the desulfurization rate. It is known that the [Si] concentration is preferably low.
特許文献1には、生石灰に金属Alを含むアルミニウム製造の副産物であるアルミ灰を添加する方法が、特許文献2には、金属Siを含むSiドロスを添加する方法が開示されている。また、特許文献3には、脱Si後の溶銑[Si]を0.20〜0.30質量%の範囲にてCaOと共にソーダ灰を用いて脱硫を行なうことで、高い脱硫率が得られるという方法が開示されている。特許文献4には、CaCO3を用いることで、反応界面積を上昇させ高い脱硫率が得られることが開示されている。 Patent Document 1 discloses a method of adding aluminum ash which is a byproduct of aluminum production containing metal Al to quick lime, and Patent Document 2 discloses a method of adding Si dross containing metal Si. Patent Document 3 states that a high degree of desulfurization can be obtained by desulfurizing hot metal [Si] after de-Si using 0.20 to 0.30% by mass using soda ash together with CaO. A method is disclosed. Patent Document 4 discloses that by using CaCO 3 , the reaction interfacial area is increased and a high desulfurization rate can be obtained.
特許文献1の方法では、金属Alに比べ安価ではあるが生石灰に比べ高価なアルミ灰を用いており、コストが高い。また、アルミ灰自体には脱硫作用がなく、石灰の配合比が低下することで、吹き込み量が増え、処理時間が長くなるという問題がある。 特許文献2の、Siドロスを添加する方法もアルミ灰同様に、コストが高くなる、Siドロス自体に脱硫作用がなく、石灰の配合比が低下する問題があり、さらに、機械攪拌脱硫での実施例であり、機械攪拌に比べ攪拌の弱いインジェクション脱硫においては、Siの酸化反応によって生じるSiO2がCaO表面にて2CaO・SiO2を生成し、CaOの反応界面積を減少させ、脱硫率が悪化する問題が言及されていない。また、特許文献3では、溶銑[Si]=0.20〜0.30質量%で、60〜80質量%の脱硫率が得られているとしている。しかし、SiO2によるCaOの反応界面積が減少し脱硫反応が停滞する問題および、溶銑[Si]=0.20〜0.30質量%では中の酸素ポテンシャルが高い問題があることから、ソーダ灰を用いており、溶銑の温度降下が大きく、コストも生石灰のみに比べ高くなる問題があり、スラグの(Na2O)濃度が高くなるので望ましくない。特許文献4には、Caの反応率をあげるのにC≧5質量%を入れることが好ましいとしており、溶銑[Si]濃度についての言及がない。 In the method of Patent Document 1, aluminum ash that is less expensive than metal Al but more expensive than quick lime is used, and the cost is high. In addition, aluminum ash itself does not have a desulfurization action, and there is a problem in that the amount of blowing increases and the processing time becomes longer due to a decrease in the mixing ratio of lime. The method of adding Si dross in Patent Document 2 also has the same problem as aluminum ash that the cost increases, Si dross itself has no desulfurization action, and there is a problem that the mixing ratio of lime is lowered. For example, in injection desulfurization, which is weaker than mechanical agitation, SiO 2 generated by the oxidation reaction of Si generates 2CaO · SiO 2 on the CaO surface, reducing the reaction interface area of CaO and desulfurization rate worsening The problem to be mentioned is not mentioned. In Patent Document 3, the hot metal [Si] is 0.20 to 0.30 mass%, and a desulfurization rate of 60 to 80 mass% is obtained. However, since the reaction interface area of CaO by SiO 2 is reduced and the desulfurization reaction is stagnant, and the hot metal [Si] = 0.20 to 0.30% by mass has a high oxygen potential, soda ash This is not desirable because the temperature drop of the hot metal is large, the cost is higher than that of quick lime, and the (Na 2 O) concentration of slag is high. Patent Document 4 states that it is preferable to add C ≧ 5 mass% in order to increase the reaction rate of Ca, and there is no mention of hot metal [Si] concentration.
本発明は、インジェクション脱硫において、上記のような問題がある炭素質、アルミ灰、Siドロスなどの還元剤およびソーダ灰を含まなくても高い脱硫率が得られる脱硫方法を提供することを目的とするものである。 It is an object of the present invention to provide a desulfurization method capable of obtaining a high desulfurization rate without including a reducing agent such as carbonaceous material, aluminum ash, Si dross and soda ash, which have the above-mentioned problems in injection desulfurization. To do.
まず、対象とする溶銑を[Si]≧0.40質量%の溶銑とする。このとき、熱力学的な脱硫限界は、[S]=0.001質量%以下であり十分低く、脱硫率の向上を見込むことができる。 First, the target hot metal is [Si] ≧ 0.40 mass%. At this time, the thermodynamic desulfurization limit is [S] = 0.001 mass% or less, which is sufficiently low, and an improvement in the desulfurization rate can be expected.
さらに、脱硫剤として、CaCO3を20質量%以上含み、残部が生石灰および蛍石からなる脱硫剤を用いる。CaCO3は、式(3)の反応により熱分解時に爆裂し粒度が細かくなり、CaOに比べ比表面積が大きくなる。このため、2CaO・SiO2の生成による脱硫反応の停滞の影響を受けにくくなる。また、CO2ガスによる攪拌効果により、CaO表面にて2CaO・SiO2が破壊され、未反応CaOが利用できる効果もあると考えられる。ただし、CaCO3を増加させすぎると、ガス量が多く、スプラッシュおよび鍋からの炎が増える影響があるため、質量40質量%未満であることが望ましい。
CaCO3=CaO+CO2 ・・・(3)
ここで、蛍石は脱硫剤に配合することで滓化促進剤として、脱硫率のさらなる向上が見込めることから、蛍石を1質量%以上含むことが必要である。また、蛍石を5質量%以上含むと脱硫剤コストが高くなることから、5%未満とするのが望ましい。
Further, as the desulfurizing agent, a desulfurizing agent containing 20% by mass or more of CaCO 3 and the balance of quick lime and fluorite is used. CaCO 3 explodes during thermal decomposition due to the reaction of the formula (3), and the particle size becomes finer, and the specific surface area becomes larger than CaO. For this reason, it becomes less susceptible to the influence of the stagnation of the desulfurization reaction due to the formation of 2CaO · SiO 2. Further, it is considered that there is an effect that 2CaO.SiO 2 is destroyed on the CaO surface due to the stirring effect by the CO 2 gas, and unreacted CaO can be used. However, if CaCO 3 is increased too much, the amount of gas is large, and there is an effect of increasing the flame from the splash and pan. Therefore, the mass is desirably less than 40% by mass.
CaCO 3 = CaO + CO 2 (3)
Here, since fluorite can be added to the desulfurization agent as a hatching accelerator and further improvement of the desulfurization rate can be expected, it is necessary to contain 1% by mass or more of fluorite. Further, if fluorite is contained in an amount of 5% by mass or more, the desulfurizing agent cost is increased, so it is desirable to make it less than 5%.
以上の知見に基づき、得られた本発明は以下の通りである。すなわち、溶銑にランスを浸漬させ、インジェクション法にて脱硫を行う工程において、溶銑[Si]≧0.40質量%の溶銑に、CaCO3を20〜40質量%含み、残部が生石灰および蛍石からなる脱硫剤を用いる溶銑脱硫方法である。 Based on the above findings, the present invention obtained is as follows. That is, in the step of immersing a lance in hot metal and performing desulfurization by the injection method, the hot metal [Si] ≧ 0.40% by mass contains 20 to 40% by mass of CaCO 3 , and the remainder from quick lime and fluorite. This is a hot metal desulfurization method using a desulfurizing agent.
本発明により、脱硫剤中に還元剤を含まずに高い脱硫率が得られ、石灰の配合比が増やせることから、脱硫処理時間の低減が図れる。また、一般的に炭素質、アルミ灰、Siドロスなどの還元剤はCaOに比べ高価であるため、脱硫剤コストが安価にできる。 According to the present invention, a high desulfurization rate can be obtained without containing a reducing agent in the desulfurizing agent, and the mixing ratio of lime can be increased, so that the desulfurization treatment time can be reduced. In general, reducing agents such as carbonaceous, aluminum ash, and Si dross are more expensive than CaO, so that the desulfurizing agent cost can be reduced.
本発明における溶銑の脱硫処理は、溶銑鍋中の溶銑に対しキャリアガスにより粉状の脱硫剤をインジェクションすることによって行う。The desulfurization treatment of the hot metal in the present invention is performed by injecting a powdery desulfurization agent into the hot metal in the hot metal ladle with a carrier gas.
表1にインジェクションによる溶銑脱硫処理を行った結果を示す。脱硫処理は、表1記載の組成を有する脱硫剤を、溶銑鍋に原単位11.5〜18.4kg/t−pigインジェクションすることにより行った。本発明の実施例1、2は、脱硫剤組成がCaCO3≧20質量%および蛍石=3質量%含み、残部が生石灰からなる脱硫剤で、溶銑[Si]≧0.40質量%の場合を示す。比較例として示したもののうち、比較例3、4は、脱硫剤組成は実施例1、2と同じで、溶銑[Si]<0.40質量%の場合であり、比較例5、6は、CaCO3=15質量%および蛍石=3質量%含み、残部が生石灰からなる脱硫剤を用いた場合、比較例7、8は、CaCO3=45質量%および蛍石=3質量%含み、残部が生石灰からなる脱硫剤を用いた場合、比較例9、10は、CaCO3=30質量%、残部が生石灰からなる脱硫剤で、蛍石を用いなかった場合の例である。 Table 1 shows the results of hot metal desulfurization treatment by injection. The desulfurization treatment was performed by injecting a desulfurization agent having the composition shown in Table 1 into a hot metal ladle in a basic unit of 11.5 to 18.4 kg / t-pig. In Examples 1 and 2 of the present invention, the desulfurization agent composition includes CaCO 3 ≧ 20 mass% and fluorite = 3 mass%, and the balance is desulfurization agent composed of quick lime, and the hot metal [Si] ≧ 0.40 mass% Indicates. Among those shown as Comparative Examples, Comparative Examples 3 and 4 are cases where the desulfurizing agent composition is the same as in Examples 1 and 2, and the hot metal [Si] <0.40% by mass. Comparative Examples 5 and 6 are When a desulfurizing agent containing CaCO 3 = 15% by mass and fluorite = 3% by mass and the balance being quick lime is used, Comparative Examples 7 and 8 include CaCO 3 = 45% by mass and fluorite = 3% by mass, and the balance When a desulfurizing agent made of quick lime is used, Comparative Examples 9 and 10 are examples in which CaCO 3 = 30% by mass and the balance is a desulfurizing agent made of quick lime and no fluorite is used.
本実施例1、2の脱硫剤では、高い脱硫率が得られた。比較例3、4は、実施例と同じ脱硫剤組成であるが、溶銑[Si]<0.40質量%であり、脱硫率が悪化する傾向が見られた。比較例5、6は、CaCO3=15質量%の脱硫剤であり、溶銑[Si]に関わらず、脱硫率が悪化する傾向がみられた。比較例7、8は、CaCO3=45%の脱硫剤であり、脱硫率に関しては問題なかったものの、スプラッシュの増大、CO2ガスによる炎の発生などの問題が発生し、適用は困難であった。比較例9、10は、蛍石=0%とした例であり、脱硫率の悪化が見られた。 In the desulfurization agents of Examples 1 and 2, a high desulfurization rate was obtained. Comparative Examples 3 and 4 had the same desulfurizing agent composition as in the Examples, but the hot metal [Si] was less than 0.40% by mass, and the desulfurization rate tended to deteriorate. Comparative Examples 5 and 6 were desulfurization agents with CaCO 3 = 15% by mass, and the desulfurization rate tended to deteriorate regardless of the hot metal [Si]. Comparative Examples 7 and 8 are desulfurization agents with CaCO 3 = 45%, and although there was no problem with the desulfurization rate, problems such as increased splash and generation of flames due to CO 2 gas occurred and were difficult to apply. It was. Comparative Examples 9 and 10 were examples in which fluorite was 0%, and a deterioration in the desulfurization rate was observed.
上記結果より、本発明によれば、溶銑[Si]≧0.40質量%に対し、脱硫剤組成中のCaCO3を20〜40質量%、残部生石灰および蛍石とした剤を用いることで、還元剤を用いない安価な脱硫剤にて、高い脱硫率が得られることが明らかとなった。 From the above results, according to the present invention, with respect to the hot metal [Si] ≧ 0.40% by mass, by using an agent that makes CaCO 3 in the desulfurization agent composition 20 to 40% by mass, the remaining quicklime and fluorite, It became clear that a high desulfurization rate can be obtained with an inexpensive desulfurization agent that does not use a reducing agent.
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JPH08260015A (en) * | 1995-03-20 | 1996-10-08 | Sumitomo Metal Ind Ltd | Pretreatment of molten iron |
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