JP5541239B2 - Steelmaking method using quick lime effectively - Google Patents
Steelmaking method using quick lime effectively Download PDFInfo
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- JP5541239B2 JP5541239B2 JP2011152346A JP2011152346A JP5541239B2 JP 5541239 B2 JP5541239 B2 JP 5541239B2 JP 2011152346 A JP2011152346 A JP 2011152346A JP 2011152346 A JP2011152346 A JP 2011152346A JP 5541239 B2 JP5541239 B2 JP 5541239B2
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- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 title claims description 163
- 235000012255 calcium oxide Nutrition 0.000 title claims description 81
- 239000000292 calcium oxide Substances 0.000 title claims description 81
- 238000000034 method Methods 0.000 title claims description 63
- 238000009628 steelmaking Methods 0.000 title claims description 15
- 239000002184 metal Substances 0.000 claims description 65
- 238000006477 desulfuration reaction Methods 0.000 claims description 41
- 230000023556 desulfurization Effects 0.000 claims description 41
- 239000002344 surface layer Substances 0.000 claims description 34
- 238000005498 polishing Methods 0.000 claims description 18
- 239000010410 layer Substances 0.000 claims description 11
- 238000005261 decarburization Methods 0.000 claims description 10
- 239000002994 raw material Substances 0.000 claims description 9
- 239000002245 particle Substances 0.000 description 24
- 238000009826 distribution Methods 0.000 description 15
- 238000007664 blowing Methods 0.000 description 8
- 239000003795 chemical substances by application Substances 0.000 description 7
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 6
- 235000011941 Tilia x europaea Nutrition 0.000 description 6
- 239000004571 lime Substances 0.000 description 6
- 239000003245 coal Substances 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 238000000926 separation method Methods 0.000 description 5
- 239000000571 coke Substances 0.000 description 4
- 238000010304 firing Methods 0.000 description 4
- 239000000295 fuel oil Substances 0.000 description 4
- 238000005096 rolling process Methods 0.000 description 4
- 235000019738 Limestone Nutrition 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000012733 comparative method Methods 0.000 description 3
- 239000006028 limestone Substances 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000007873 sieving Methods 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 2
- 238000001354 calcination Methods 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 229910001882 dioxygen Inorganic materials 0.000 description 2
- 238000005194 fractionation Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 230000012447 hatching Effects 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 238000002203 pretreatment Methods 0.000 description 2
- 239000002893 slag Substances 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 1
- 238000010835 comparative analysis Methods 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 230000003009 desulfurizing effect Effects 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 239000010436 fluorite Substances 0.000 description 1
- -1 fluorite Chemical class 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 150000002366 halogen compounds Chemical class 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 238000007790 scraping Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 239000002436 steel type Substances 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
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- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
- Carbon Steel Or Casting Steel Manufacturing (AREA)
Description
本発明は生石灰を効率的に使用することを特徴とする製鋼方法に関する。 The present invention relates to a steelmaking method characterized by efficiently using quicklime.
製鋼工程において、主に造滓剤として使用されるものに生石灰がある。生石灰は、溶銑脱硫工程では溶銑中の［Ｓ］除去、溶銑脱燐工程では溶銑中の［Ｐ］除去、溶銑の脱燐・脱炭工程ではカバースラグ形成を主たる目的として多量に使用されている。しかし、生石灰は、Ｓ分を含有する熱源（石炭、コークス、重油等）を用いて石灰石を焼成して製造するため、製造された生石灰の表面は内部に比べてＳ濃度が高くなる。この生石灰を原料として使用することにより、溶銑や溶鋼中の［Ｓ］ピックアップが起こり、それを除去する為のロスコストが発生するという問題点がある。従って、製鋼を効率よく行うためには、生石灰自体の不純物が少ない方が良い。Ｓ含有濃度の低い生石灰を製造するには、焼成用の熱源としてＳ含有量が低いものを使用する必要があり、コストアップは避けられない。 In the steelmaking process, quick lime is mainly used as a slagging agent. Quick lime is used in large quantities mainly for the purpose of removing [S] in hot metal in the hot metal desulfurization process, removing [P] in hot metal in the hot metal dephosphorization process, and forming cover slag in the dephosphorization / decarburization process of hot metal. . However, quicklime is produced by calcining limestone using a heat source containing S (coal, coke, heavy oil, etc.), so the surface of the produced quicklime has a higher S concentration than the inside. By using this quicklime as a raw material, there is a problem that [S] pick-up occurs in hot metal or molten steel, resulting in a loss cost for removing it. Therefore, in order to perform steelmaking efficiently, it is better that the quick lime itself has less impurities. In order to produce quicklime having a low S-containing concentration, it is necessary to use a low heat source for firing as a heat source for firing, and an increase in cost is inevitable.
これまで報告されている生石灰の不純物低減技術として、焼成された生石灰表面を研磨して、Ｓ含有率が高い表層部分とＳ含有率が低い内層部分とに分別することが提案されている。そのための手段として、特許文献１には、筒状回転体の内部に生石灰を入れ、回転運動による転動摩耗作用を利用して、生石灰表面の汚染物質を除去する方法が紹介されている。しかし、特許文献１には、除去されたＳ含有率が高い表層部分の利用に関しては全く記載が無い。 As a technique for reducing impurities of quicklime that has been reported so far, it has been proposed to grind the calcined quicklime surface and separate it into a surface layer portion having a high S content and an inner layer portion having a low S content. As a means for that purpose, Patent Document 1 introduces a method in which quick lime is put inside a cylindrical rotating body, and contaminants on the surface of quick lime are removed by utilizing a rolling wear action by a rotational motion. However, Patent Document 1 has no description regarding the use of the removed surface layer portion having a high S content.
一方、製鋼工程における溶銑中の［Ｓ］を除去する方法として、溶銑脱硫工程において脱Ｓ剤として生石灰を添加し、インペラーと呼ばれる攪拌棒を用いて機械的に溶銑を攪拌し、化学反応によって硫黄を除去するＫＲ法が広く用いられている。この方法は、脱Ｓ剤として添加する生石灰を溶解させ、化学反応によって［Ｓ］を除去する方法であるが、生石灰単体の融点は２０００℃以上と高温であり、溶解が困難である。そのため、融点を低下させるための滓化促進剤が一般的には用いられる。しかし、最近では環境問題の観点から一般的な滓化促進剤であるホタル石などのハロゲン化合物を使わない技術の開発が行われている。 On the other hand, as a method for removing [S] in the hot metal in the steelmaking process, quick lime is added as a desulfurizing agent in the hot metal desulfurization process, the hot metal is mechanically stirred using a stirring rod called an impeller, and sulfur is generated by a chemical reaction. The KR method is widely used to remove the. This method is a method in which quicklime added as a de-S agent is dissolved and [S] is removed by a chemical reaction. However, the melting point of quicklime alone is as high as 2000 ° C. and is difficult to dissolve. Therefore, hatching accelerators for lowering the melting point are generally used. However, recently, technology that does not use halogen compounds such as fluorite, which is a general hatching accelerator, has been developed from the viewpoint of environmental problems.
そのＫＲでの脱硫能向上方法として、特許文献２などに、ＫＲで溶銑上方から生石灰を吹き付け、脱硫能の向上を図る方法が提案されている。この特許文献には、材料粒径、吹き込み速度は規定されているが、使用材料の成分に関しては明記されていない。
As a method for improving the desulfurization ability in KR,
また、溶銑中の［Ｐ］を除去する方法として、溶銑脱燐工程として上底吹き転炉に溶銑を装入した後、造滓剤として生石灰を添加し、底吹きガスによる撹拌を行いながら、溶銑上方より酸素ガスを吹き付け、化学反応により［Ｐ］を除去する方法が用いられている。 In addition, as a method of removing [P] in the hot metal, after the hot metal is charged into the top bottom blowing converter as the hot metal dephosphorization step, quick lime is added as a slagging agent, and stirring with the bottom blowing gas is performed. A method of blowing oxygen gas from above the hot metal and removing [P] by a chemical reaction is used.
さらに、溶銑中の［Ｃ］を除去する方法として、溶銑の脱燐・脱炭工程として上底吹き転炉に溶銑を装入した後、上方より酸素ガスを吹き付けるに際し、溶銑上にカバースラグ形成用の生石灰を投入して、溶銑中の［Ｃ］をＣＯガスとして除去する際のスピッティングやダストロスの発生を抑制する方法が用いられている。 Furthermore, as a method for removing [C] in the hot metal, cover slag is formed on the hot metal when oxygen gas is blown from above after the hot metal is charged into the top bottom blowing converter as a dephosphorization / decarburization process of hot metal A method for suppressing generation of spitting and dust loss when removing [C] in hot metal as CO gas is used.
本発明の目的は、コストアップを抑えて生石灰を製造し、それを含有Ｓ濃度により分別して、その全部を各製鋼プロセスの特性に合わせて使い分けることによって、生石灰の利用効率を高め、製鋼方法全体を合理化する方法を提供することである。 The purpose of the present invention is to produce quicklime with reduced cost increase, sort it according to the concentration of contained S, and use all of them according to the characteristics of each steelmaking process, thereby improving the utilization efficiency of quicklime and the whole steelmaking method Is to provide a way to streamline
上記課題を解決すべく提供される本発明は次のとおりである。
焼成された生石灰表面を研磨して、Ｓ含有率が高い表層部分とＳ含有率が低い内層部分とに分別し、該表層部分は溶銑脱硫工程において脱硫用副原料として用い、該内層部分は溶銑脱燐工程または溶銑の脱燐・脱炭工程において、脱燐用副原料として用いることを特徴とする製鋼方法。
The present invention provided to solve the above problems is as follows.
The surface of the calcined lime is polished and separated into a surface layer portion having a high S content and an inner layer portion having a low S content, and the surface layer portion is used as an auxiliary raw material for desulfurization in the hot metal desulfurization step. A steelmaking method characterized by being used as an auxiliary raw material for dephosphorization in a dephosphorization step or a hot metal dephosphorization / decarburization step.
前記研磨は、前記表層部分の割合が３５〜４５質量％になるように管理して行うことが好ましい。 It is preferable to perform the polishing so that the ratio of the surface layer portion is 35 to 45% by mass.
本発明により、Ｓ分を含む熱源（石炭、コークス、重油等）を用いて焼成を行うことによりコストアップを抑えて生石灰を製造し、製造された生石灰をＳ含有率により分別し、その全部を各製鋼プロセスの特性に合わせて使い分けることによって、製鋼方法全体を合理化することができる。 According to the present invention, quick calcined lime is produced while suppressing the increase in cost by firing using a heat source (coal, coke, heavy oil, etc.) containing S, and the produced quick lime is separated according to the S content, By using properly according to the characteristics of each steelmaking process, the whole steelmaking method can be rationalized.
（１）生石灰の製造と分別
生石灰は石灰石を原料としてロータリーキルン等で焼成することにより製造されるが、その焼成の際に加熱源としてＳ分を含んでいる炭材や重油を用いるために、製造された生石灰の表層部分はその内部に比べてＳ含有濃度が高いことが知られている。そのため、特許文献１のように、生石灰の表層部分を研磨して除去する方法が開発されている。しかし、特許文献１では、研磨して除去した生石灰の表層部分の用途は記載されていない。したがって、その除去基準についても記載されていない。
(1) Manufacture and fractionation of quick lime Quick lime is manufactured by calcining limestone as a raw material in a rotary kiln or the like. It is known that the surface layer portion of the quicklime that has been made has a higher S-containing concentration than the inside. Therefore, as disclosed in Patent Document 1, a method for polishing and removing the surface layer portion of quicklime has been developed. However, in patent document 1, the use of the surface layer part of the quicklime removed by grinding | polishing is not described. Therefore, the removal standard is not described.
一方、製鋼工程には溶銑の脱硫を目的とする溶銑脱硫工程と、溶銑の脱燐を目的とする溶銑脱燐工程と、溶銑の脱燐・脱炭を目的とする溶銑の脱燐・脱炭工程とがあり、それぞれに生石灰に対する品質要求基準が異なっている。この点に着目して、生石灰の製造と分離工程において適切な製造・分離基準を設定することによって、製造した生石灰の全量を有効利用し、しかも製鋼工程全体の効率を落とさない合理的な製鋼方法が実現できるという着想を得た。 On the other hand, in the steelmaking process, the hot metal desulfurization process for hot metal desulfurization, the hot metal dephosphorization process for hot metal dephosphorization, and the hot metal dephosphorization and decarburization for hot metal dephosphorization and decarburization. There are processes, and each has different quality requirements for quicklime. Focusing on this point, by setting appropriate production and separation standards in the production and separation process of quicklime, a rational steelmaking method that effectively uses the total amount of quicklime produced and does not reduce the efficiency of the entire steelmaking process I got the idea that can be realized.
そこで、最初に生石灰の製造と分離に係る適切な基準を検討する。
まず、従来ＫＲで使用していた生石灰の粒径分布と、その粒径分布と同等の粒径分布を有するようにＳ分を含む熱源（石炭、コークス、重油等）を用いて焼成した生石灰を、特許文献１に記載されている方法と同様な転動摩耗を利用した方法を用いて表層部分を研磨した後であって、その研磨された表層部分を分別する前の生石灰の粒径分布とを、図１に対比して示す。従来の生石灰は、焼成後に粒径が３.８ｍｍ以下になるように粉砕したものを使用していて、その粒径分布は２ｍｍ近辺を中心（最頻値）とし、その全体のＳ含有濃度は、採取したサンプルにより異なるが、０.０１５〜０.０３０質量％の範囲内であった。
Therefore, we first consider appropriate standards for quicklime production and separation.
First, quick lime calcined using a heat source (coal, coke, heavy oil, etc.) containing S so as to have a particle size distribution of quick lime conventionally used in KR and a particle size distribution equivalent to the particle size distribution. And the particle size distribution of quicklime after the surface layer portion is polished using a method using rolling wear similar to the method described in Patent Document 1, and before the polished surface layer portion is separated. Is shown in comparison with FIG. Conventional quicklime is used that is pulverized so that the particle size is 3.8 mm or less after firing, the particle size distribution is centered around 2 mm (mode), and the total S-containing concentration is Depending on the sample collected, it was in the range of 0.015 to 0.030% by mass.
一方、本発明に係る生石灰の「表層高Ｓ部分」とは、焼成された生石灰を特許文献１に記載されたような方法と同様な転動摩耗を利用した方法を用いて表面研磨して得られる表層部分を分別採取したものであり、図１に示す粒径分布（粒径１ｍｍ以下が３５〜６０質量％である分布）を有するものから、その粒径１ｍｍ以下の部分を篩い分けて得ることができる。今回の検討調査で得た「表層高Ｓ部分」のＳ含有濃度は、０.１００〜０.３００質量％の範囲内であった。従って、表層部のＳ含有濃度は、従来ＫＲで使用していた生石灰に比べて約７〜１０倍も高かった。 On the other hand, the “surface layer high S portion” of quicklime according to the present invention is obtained by surface-polishing calcined quicklime using a method using rolling wear similar to the method described in Patent Document 1. The surface layer portion obtained is separated and collected, and the portion having the particle size of 1 mm or less is obtained by sieving from the one having the particle size distribution (distribution in which the particle size of 1 mm or less is 35 to 60% by mass) shown in FIG. be able to. The S-containing concentration in the “surface layer high S portion” obtained in this study was in the range of 0.100 to 0.300% by mass. Therefore, the S content concentration in the surface layer was about 7 to 10 times higher than that of quick lime conventionally used in KR.
表層部分を分離した後に残る内層部分は、後述するように、脱燐用の副原料となる。この内層部分の粒径分布は、図１に示した粒径分布のうちの粒径１ｍｍより大きい部分であって、今回の検討調査におけるその部分の粒径分布の最頻値は、表面研磨前とほぼ同じ２ｍｍ近辺であった。また、そのＳ含有濃度は０.０１５〜０.０３０質量％の範囲内で、従来ＫＲで使用していた生石灰と同等レベルであった。したがって、表層高Ｓ部分が除去されているために、Ｓ分を多く含む熱源を用いて焼成した影響を排除することができていると確認された。 As will be described later, the inner layer portion remaining after the separation of the surface layer portion becomes an auxiliary raw material for dephosphorization. The particle size distribution of the inner layer portion is a portion of the particle size distribution shown in FIG. 1 larger than the particle size of 1 mm. It was around 2 mm, which is almost the same as. Moreover, the S content concentration was in the range of 0.015 to 0.030% by mass and was at the same level as quicklime used in the past KR. Therefore, it was confirmed that the effect of baking using a heat source containing a large amount of S could be eliminated because the surface high S portion was removed.
ここで、生石灰の表面を研磨する際の製造管理基準としては、製造された生石灰の３５〜６０質量％を削り落すように設定することが好ましい。それにより、Ｓ含有濃度が高い表層部分を実質的に完全に削り落すことができる。また、表層部分を削り落す方法は、表層部研磨後の粒径１ｍｍ以下の部分の質量比率が全体の３５〜６０％であれば、特許文献１に記載されている方法には限られない。但し、製造された生石灰の３５〜４５質量％を削り落せば、表層が高Ｓ濃度化した影響を実質的に排除することができるので、Ｓ含有濃度の高い粉状生石灰（表層高Ｓ部分）の生成量増加を避けたい場合には、３５〜４５質量％を削り落すように管理することが有利であるといえる。 Here, it is preferable to set so that 35-60 mass% of the manufactured quicklime is shaved off as a manufacturing control standard at the time of grind | polishing the surface of quicklime. Thereby, the surface layer portion having a high S-containing concentration can be scraped off completely. Moreover, the method of scraping off the surface layer portion is not limited to the method described in Patent Document 1 as long as the mass ratio of the portion having a particle diameter of 1 mm or less after polishing of the surface layer portion is 35 to 60% of the whole. However, if 35 to 45% by mass of the manufactured quicklime is scraped off, the effect of the surface layer having a high S concentration can be substantially eliminated, so powdered quicklime having a high S-containing concentration (surface layer high S portion) When it is desired to avoid an increase in the amount of produced, it can be said that it is advantageous to manage so as to cut off 35 to 45% by mass.
この表面研磨後の、微粉状の表層高Ｓ部分と、より粗大な内層低Ｓ部分との分別は、篩分けにより行うことができる。図１に示した例では、目の大きさが１.０ｍｍの篩を用いた篩分けにより、篩下である表層高Ｓ部分と篩上である内層低Ｓ部分とに分離した。篩の目の大きさは、表面研磨前の生石灰の粒径に応じて適宜変更しうる。 After the surface polishing, the fine powdery surface layer high S portion and the coarser inner layer low S portion can be separated by sieving. In the example shown in FIG. 1, separation was performed by sieving using a sieve having a mesh size of 1.0 mm into a surface high S portion that is under the sieve and an inner low S portion that is on the sieve. The size of the sieve mesh can be appropriately changed according to the particle size of the quicklime before surface polishing.
（２）溶銑脱硫工程での使用
溶銑の脱硫工程では、一般に表１に示すような成分を有する溶銑を対象として、脱硫処理後の溶銑中Ｓ濃度を高くとも０.０１０質量％以下であって、製造する鋼種によっては０.００１０質量％以下にすることが可能な脱硫能力が要求される。このとき、溶銑から除去されるＳ質量は、対象溶銑１トン当たり０.１０〜０.１９ｋｇ以上である。
(2) Use in hot metal desulfurization process In the hot metal desulfurization process, hot metal having components as shown in Table 1 is generally targeted, and the S concentration in the hot metal after desulfurization treatment is at most 0.010 mass% or less. Depending on the steel type to be manufactured, a desulfurization capacity capable of being 0.0010 mass% or less is required. At this time, the S mass removed from the hot metal is 0.10 to 0.19 kg or more per ton of the target hot metal.
一方、溶銑の脱硫工程で使用する生石灰量は、対象とする溶銑１トン当たり約１０ｋｇ以下であるから、その生石灰中に含有されるＳ％が０.２質量％違うと、脱硫工程に持ち込まれるＳ質量は０.０１〜０.０２ｋｇ違うことに相当する。このＳ質量の違いは、前述した溶銑から除去されるＳ質量が、対象溶銑１トン当たり０.１０〜０.１９ｋｇ以上であることと比べて、約１／１０程度に過ぎない。 On the other hand, the amount of quicklime used in the hot metal desulfurization process is about 10 kg or less per ton of hot metal, so if the S% contained in the quicklime is 0.2 mass% different, it is brought into the desulfurization process. The S mass corresponds to a difference of 0.01 to 0.02 kg. This difference in S mass is only about 1/10 compared to the fact that the S mass removed from the hot metal described above is 0.10 to 0.19 kg or more per ton of the target hot metal.
従って、溶銑脱硫処理を少し改善すれば、脱硫剤に付随して持ち込まれるＳ質量の増加を、脱硫処理後の溶銑中Ｓ％に影響させないようにすることができる。つまり、脱硫工程では、除去されるＳ量が大きいために、表面研磨で分離された、Ｓ含有濃度が０.１００〜０.３００質量％の表層高Ｓ部分の生石灰でも、十分に脱硫用の副原料として使用できるのである。 Therefore, if the hot metal desulfurization treatment is slightly improved, an increase in S mass brought along with the desulfurization agent can be prevented from affecting the S% in the hot metal after the desulfurization treatment. That is, in the desulfurization process, since the amount of S to be removed is large, even the quick lime of the surface layer high S portion separated by surface polishing and having an S content concentration of 0.100 to 0.300 mass% is sufficiently desulfurized. It can be used as an auxiliary material.
前記したように、表面研磨した後に分離される表層高Ｓ部分の生石灰は粉状であって、従来のＫＲ用生石灰よりも粒径が細かい。したがって、溶銑脱硫剤として好ましい細粒条件を満たしており、脱硫用に好都合である。 As described above, the quick lime in the surface S portion separated after the surface polishing is powdery and has a smaller particle diameter than the conventional quick lime for KR. Therefore, it satisfies the fine particle conditions preferable as a hot metal desulfurization agent, and is convenient for desulfurization.
そこで、ＫＲ法による脱硫について従来技術と本発明との比較評価試験を行った。その結果の一例を以下に示す。 Therefore, a comparative evaluation test between the prior art and the present invention was conducted for desulfurization by the KR method. An example of the result is shown below.
表２で示した溶銑成分で脱硫処理をＫＲ法で実施した。
図２に脱硫用生石灰原単位と脱硫率との関係を示す。横軸は投入した生石灰量、縦軸は(処理前[Ｓ]−処理後[Ｓ])／処理前[Ｓ]×１００で得られる脱硫率を示している。処理した溶銑は２２０〜２３０トンであり、温度は１３２０℃〜１３５０℃で撹拌時間は１２分であった。
Desulfurization treatment was performed by the KR method using the hot metal components shown in Table 2.
FIG. 2 shows the relationship between the quick lime unit for desulfurization and the desulfurization rate. The horizontal axis represents the amount of quicklime introduced, and the vertical axis represents the desulfurization rate obtained by (pre-treatment [S] −post-treatment [S]) / pre-treatment [S] × 100. The treated hot metal was 220 to 230 tons, the temperature was 1320 ° C. to 1350 ° C., and the stirring time was 12 minutes.
図２における本発明とは、表層高Ｓ部分の生石灰を添加する方法を意味する。一方、従来法とは、ＫＲにて脱Ｓ処理される溶銑上方のホッパーより、従来ＫＲ用として図１に示した生石灰を添加する方法を意味する。また、比較法とは、従来ＫＲ用生石灰を粉砕し、粒度を表層高Ｓ部分とほぼ同等にして添加する方法を意味する。 The present invention in FIG. 2 means a method of adding quick lime having a surface high S portion. On the other hand, the conventional method means a method of adding quick lime shown in FIG. 1 for the conventional KR from a hopper above the hot metal to be de-S treated by KR. In addition, the comparative method means a method of adding conventional lime for quick lime by pulverizing and making the particle size substantially equal to the surface high S portion.
図２に示される結果より、従来法よりも粉状生石灰を使用する比較法および本発明の方が、同程度の脱硫用生石灰量でも脱硫率が向上する効果が得られた。さらに、本発明である表層高Ｓ部分を使用しても、比較法と比べて脱硫率の悪化は見られず、生石灰を有効利用できるという結果が得られた。 From the results shown in FIG. 2, the comparative method using powdered quicklime and the present invention have an effect of improving the desulfurization rate even with the same amount of quicklime for desulfurization as compared with the conventional method. Further, even when the surface high S portion according to the present invention was used, the desulfurization rate was not deteriorated as compared with the comparative method, and the result that quick lime could be used effectively was obtained.
本発明に係る表層高Ｓ部分の生石灰を用いても、その生石灰が細かいために、その含有Ｓ％が高いことによる溶銑脱硫率への影響が現われず、表層高Ｓ部分の生石灰を用いることによる脱硫能率やコストへの影響を回避できることが確認された。 Even when the quick lime of the surface layer high S portion according to the present invention is used, since the quick lime is fine, the effect of the high S content is not exerted on the hot metal desulfurization rate, and by using the quick lime of the surface layer high S portion. It was confirmed that the effects on desulfurization efficiency and cost can be avoided.
なお、焼成された生石灰における表層が除去された部分、つまり内層部分はＳ含有濃度が低いため、溶銑脱硫処理において使用される副原料の生石灰として、表層高Ｓ部分に加えてこの内層部分が含まれていたとしても、その処理に悪影響が及ぼされることはない。 The portion of the calcined quick lime from which the surface layer has been removed, that is, the inner layer portion has a low S-containing concentration, so that the inner layer portion is included in addition to the surface layer high S portion as the auxiliary lime used in the hot metal desulfurization process. Even if it is, the processing will not be adversely affected.
（３）溶銑の脱燐工程、脱燐・脱炭工程での使用
溶銑の脱燐工程は、多くの場合は溶銑脱硫後の溶銑を対象とし、上底吹き転炉等を用いて脱燐処理後の溶銑中Ｐ％を０.０２０質量％以下程度にする。その場合、生石灰を溶銑１トン当たり１０〜３０ｋｇ程度を用いるが、脱燐は酸化反応なので同時に脱硫することは殆ど期待できない。この状況は、溶銑を脱炭して溶鋼を製造する脱燐・脱炭工程においても同様である。
(3) Use of hot metal in dephosphorization process, dephosphorization / decarburization process Hot metal dephosphorization process is often used for hot metal after hot metal desulfurization and dephosphorization treatment using top-bottom blowing converter etc. The P% in the hot metal after that is adjusted to about 0.020 mass% or less. In that case, about 10 to 30 kg of quicklime is used per ton of hot metal, but since dephosphorization is an oxidation reaction, it is hardly expected to desulfurize at the same time. This situation is the same in the dephosphorization / decarburization process in which molten steel is decarburized to produce molten steel.
このような状況で、その生石灰中に含有されるＳ％が０.２質量％違うと、脱燐工程に持ち込まれるＳ質量は０.０２〜０.０６ｋｇ違うことに相当する。このＳ質量の違いは、前述した脱硫処理後の溶銑に含まれるＳ質量が、対象溶銑１トン当たり０.０１〜０.１０ｋｇ以下であることと比べて同程度である。したがって、図１に示した生石灰を脱燐剤として上底吹き転炉に投入し、脱燐処理を行うと、図３に示すように溶銑に含まれるＳ％は大きく上昇してしまう。つまり、［Ｓ］ピックアップを生じてしまう。 In such a situation, if the S% contained in the quicklime is 0.2 mass% different, the S mass brought into the dephosphorization process is equivalent to 0.02 to 0.06 kg. The difference in S mass is comparable to that the S mass contained in the hot metal after the above-described desulfurization treatment is 0.01 to 0.10 kg or less per ton of the target hot metal. Therefore, when the quick lime shown in FIG. 1 is put into the top bottom blowing converter as a dephosphorizing agent and the dephosphorization process is performed, as shown in FIG. 3, the S% contained in the hot metal is greatly increased. That is, [S] pickup is generated.
この結果より、本発明に係る表層高Ｓ部分の生石灰は、溶銑の脱燐工程または脱燐・脱炭工程で用いることは適切でなく、(２)で述べたように溶銑の脱硫工程で用いることが合理的であると判断される。 From this result, it is not appropriate to use the hot lime of the surface high S portion according to the present invention in the hot metal dephosphorization process or the dephosphorization / decarburization process, and as described in (2), it is used in the hot metal desulfurization process. Is considered reasonable.
一方、表層高Ｓ部分が分離された後に残る内層低Ｓ部分は、Ｓ含有濃度が低減しているため、溶銑の脱燐工程または脱燐・脱炭工程で使用しても、［Ｓ］ピックアップを生じる恐れがないので、これらの工程に使用することが合理的である。 On the other hand, the inner low S portion remaining after the surface high S portion has been separated has a reduced S content, so even if it is used in the hot metal dephosphorization process or dephosphorization / decarburization process, the [S] pickup Therefore, it is reasonable to use these steps.
ロータリーキルンを用いて、主として微粉炭からなる熱源により石灰石を焼成して生石灰を製造した後、粒径が３.８ｍｍ以下になるように篩って、従来ＫＲ用の生石灰と同等の粒径分布を有する生石灰を得た。そのＳ濃度は全体平均で０.０８５質量％であった。 Using a rotary kiln, limestone is calcined with a heat source mainly composed of pulverized coal to produce quicklime, and then sifted to a particle size of 3.8 mm or less to obtain a particle size distribution equivalent to conventional quicklime for KR. The obtained quicklime is obtained. The S concentration was 0.085% by mass as an overall average.
得られた生石灰を、特許文献１に開示された装置に類似する表面研磨装置を用いて、表面研磨を行った。その際に、表層高Ｓ部分とする質量比率が、表面研磨装置に投入した生石灰の３５質量％となるように表面研磨処理を管理した結果、その粒径分布は図１に示したのと同様であった。表面研磨装置から取り出した生石灰を、目の大きさが１.０ｍｍの篩で分級して、篩下の表層高Ｓ部分と、篩上の内層低Ｓ部分とに分別した結果、表層高Ｓ部分の生石灰のＳ濃度は０.２０質量％であった。一方、内層低Ｓ部分の生石灰のＳ濃度は０.０２３質量％であった。 The obtained quicklime was subjected to surface polishing using a surface polishing apparatus similar to the apparatus disclosed in Patent Document 1. At that time, as a result of managing the surface polishing treatment such that the mass ratio of the surface layer height S portion is 35% by mass of the quicklime charged in the surface polishing apparatus, the particle size distribution is the same as that shown in FIG. Met. As a result of classifying quick lime taken out from the surface polishing apparatus with a sieve having a mesh size of 1.0 mm, and classifying the lime into a surface high S portion under the sieve and an inner low S portion on the sieve, the surface high S portion The S concentration of quicklime was 0.20% by mass. On the other hand, the S concentration of quicklime in the inner layer low S portion was 0.023 mass%.
その表層高Ｓ部分の生石灰を、表２に示した溶銑２２０〜２３０トンを対象としてＫＲ脱硫装置を用いて脱硫処理する際の脱硫用副原料とした。その生石灰の使用は、インペラーを回転させてから対象溶銑トン当たり４〜６ｋｇを連続的に供給する方法を用い、処理後の溶銑中Ｓ濃度を０.００１〜０.０１０質量％と安定して所定濃度以下にすることができた。 The quick lime of the surface layer high S portion was used as a desulfurization auxiliary raw material for desulfurization treatment using 220 to 230 tons of hot metal shown in Table 2 using a KR desulfurization apparatus. The use of the quicklime uses a method of continuously supplying 4 to 6 kg per ton of the target hot metal after rotating the impeller, and the S concentration in the hot metal after the treatment is stabilized at 0.001 to 0.010% by mass. The concentration could be reduced below the predetermined concentration.
また、表面研磨と分別後に表層から分離された残り６５質量％の内層低Ｓ部分の生石灰は、その全量を、上底吹き型転炉を用いる溶銑脱燐工程の脱燐用副原料として用い、通常の溶銑脱燐処理と同等の処理結果を得ることができた。 Further, the remaining 65 mass% of the inner layer low S portion quick lime separated from the surface layer after the surface polishing and fractionation, the entire amount thereof is used as an auxiliary raw material for dephosphorization in the hot metal dephosphorization process using an upper bottom blowing converter, A treatment result equivalent to the normal hot metal dephosphorization treatment could be obtained.
Claims (2)
該表層部分は溶銑脱硫工程において脱硫用副原料として用い、
該内層部分は溶銑脱燐工程において、または溶銑の脱燐・脱炭工程において、脱燐用副原料として用いることを特徴とする製鋼方法。 The calcined quicklime surface is polished and separated into a surface layer portion with a high S content and an inner layer portion with a low S content,
The surface layer portion is used as an auxiliary raw material for desulfurization in the hot metal desulfurization process,
The steel making method, wherein the inner layer portion is used as an auxiliary raw material for dephosphorization in a hot metal dephosphorization step or in a hot metal dephosphorization / decarburization step.
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