JPS6125763B2 - - Google Patents
Info
- Publication number
- JPS6125763B2 JPS6125763B2 JP13303978A JP13303978A JPS6125763B2 JP S6125763 B2 JPS6125763 B2 JP S6125763B2 JP 13303978 A JP13303978 A JP 13303978A JP 13303978 A JP13303978 A JP 13303978A JP S6125763 B2 JPS6125763 B2 JP S6125763B2
- Authority
- JP
- Japan
- Prior art keywords
- hot metal
- calcium carbide
- desulfurization
- blown
- quicklime
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 229910052751 metal Inorganic materials 0.000 claims description 158
- 239000002184 metal Substances 0.000 claims description 158
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims description 80
- 239000005997 Calcium carbide Substances 0.000 claims description 64
- CLZWAWBPWVRRGI-UHFFFAOYSA-N tert-butyl 2-[2-[2-[2-[bis[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]amino]-5-bromophenoxy]ethoxy]-4-methyl-n-[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]anilino]acetate Chemical compound CC1=CC=C(N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)C(OCCOC=2C(=CC=C(Br)C=2)N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)=C1 CLZWAWBPWVRRGI-UHFFFAOYSA-N 0.000 claims description 64
- 238000000034 method Methods 0.000 claims description 45
- 239000002893 slag Substances 0.000 claims description 44
- 239000000292 calcium oxide Substances 0.000 claims description 40
- 235000012255 calcium oxide Nutrition 0.000 claims description 40
- 239000003795 chemical substances by application Substances 0.000 claims description 36
- 239000012159 carrier gas Substances 0.000 claims description 33
- 239000010459 dolomite Substances 0.000 claims description 25
- 229910000514 dolomite Inorganic materials 0.000 claims description 25
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 22
- 229910052799 carbon Inorganic materials 0.000 claims description 21
- 230000003009 desulfurizing effect Effects 0.000 claims description 19
- 239000007787 solid Substances 0.000 claims description 18
- MYFXBBAEXORJNB-UHFFFAOYSA-N calcium cyanamide Chemical compound [Ca+2].[N-]=C=[N-] MYFXBBAEXORJNB-UHFFFAOYSA-N 0.000 claims description 10
- 239000000654 additive Substances 0.000 claims description 9
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 5
- 229910001873 dinitrogen Inorganic materials 0.000 claims description 5
- 230000000996 additive effect Effects 0.000 claims description 4
- 238000006477 desulfuration reaction Methods 0.000 description 73
- 230000023556 desulfurization Effects 0.000 description 73
- 238000006243 chemical reaction Methods 0.000 description 12
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 11
- 229910052717 sulfur Inorganic materials 0.000 description 11
- 239000011593 sulfur Substances 0.000 description 11
- 239000002006 petroleum coke Substances 0.000 description 7
- 229910000831 Steel Inorganic materials 0.000 description 6
- 239000010959 steel Substances 0.000 description 6
- 239000007789 gas Substances 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 230000001590 oxidative effect Effects 0.000 description 5
- 239000000843 powder Substances 0.000 description 5
- 238000003756 stirring Methods 0.000 description 5
- 229910004298 SiO 2 Inorganic materials 0.000 description 4
- 238000007664 blowing Methods 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 229910000805 Pig iron Inorganic materials 0.000 description 3
- 238000002347 injection Methods 0.000 description 3
- 239000007924 injection Substances 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000005979 thermal decomposition reaction Methods 0.000 description 2
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical compound [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 description 1
- 239000006229 carbon black Substances 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- UBAZGMLMVVQSCD-UHFFFAOYSA-N carbon dioxide;molecular oxygen Chemical compound O=O.O=C=O UBAZGMLMVVQSCD-UHFFFAOYSA-N 0.000 description 1
- 239000003610 charcoal Substances 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 239000000571 coke Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- -1 etc. Substances 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910000473 manganese(VI) oxide Inorganic materials 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000006263 metalation reaction Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- 239000005011 phenolic resin Substances 0.000 description 1
- 229920001568 phenolic resin Polymers 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 235000017550 sodium carbonate Nutrition 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- 239000011343 solid material Substances 0.000 description 1
- 239000002341 toxic gas Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C1/00—Refining of pig-iron; Cast iron
- C21C1/02—Dephosphorising or desulfurising
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
Description
本発明は容器内に収納された溶銑内に浸漬した
ランスパイプを通じて搬送ガスと共に粉状のカル
シウムカーバイドを吹き込む溶銑の脱硫方法に関
し、特に本発明は溶銑内に生石灰、焼成ドロマイ
トの何れか１種または２種と炭素とを主体とする
添加物を吹き込んだ後、カルシウムカーバイドを
主体とする脱硫剤を溶銑内に吹き込む溶銑の脱硫
方法に関するものである。
近年鋼の新製品開発、より高度な品質要求から
硫黄含有量が0.015％程度の低硫鋼や0.005％程度
の極低硫鋼の需要が大きくクローズアツプされ、
併わせて最近の高炉の高能率操業や原料事情から
溶銑内の硫黄含有量が益々増加する傾向にあり、
溶銑の炉外脱硫は今日の製鉄所にとつて不可欠の
条件になつてきた。
溶銑の炉外脱硫に関しては古くから広く研究が
行なわれ、一般に溶銑の炉外脱硫方法としてはカ
ルシウムカーバイド、ソーダ灰、生石灰などを用
いた粉末吹込法、ガス吹込撹拌方法、インペラー
撹拌法、揺動取鍋法、回転ドラム法などが知られ
ているが、現状では様々の経過を経て、カルシウ
ムカーバイドを主体とする脱硫剤を用いた粉末吹
込法およびインペラー撹拌法が広く採用されてい
る。
しかしながらこの粉末吹込法およびインペラー
撹拌法による脱硫処理においてはカルシウムカー
バイドの利用効率が15〜30％と低く、残りの85〜
70％のカルシウムカーバイドは溶銑内の硫黄と反
応せず全くのロスとなつている。近年の石油危機
以後の大幅な電力料金の値上げからカルシウムカ
ーバイドの価格は高騰しており、溶銑の脱硫処理
におけるカルシウムカーバイドの利用効率を向上
させることは鋼のコストを低減させる上から鉄鋼
業の大きな課題の一つである。
粉末吹込法は溶銑内下部に浸漬したランスパイ
プを通じて窒素ガスなどの搬送ガスと共にカルシ
ウムカーバイド、生石灰などの粉状脱硫剤を吹き
込み、溶銑と脱硫剤とを充分に接触させようとす
る方法である。この方法においては脱硫剤の粒径
を20〜30μと極めて小さくすることができ、脱硫
剤自体の表面積は非常に大きい。しかしながら搬
送ガスと共に溶銑内へ吹き込まれた脱硫剤の大部
分は搬送ガスの気泡から飛び出すことができずに
気泡内に閉じ込められて溶銑と接触することがで
きないと共に、溶銑内へ吹き込まれた脱硫剤の浮
上速度が速く、溶銑と接触している時間が数秒と
かなり短いため、溶銑内へ吹き込まれた脱硫剤は
溶銑内浮上過程で充分に溶銑と接触することがで
きず、その大部分が未反応の状態で溶銑表面へ浮
上する。即ち脱硫剤として硫黄と反応し易いカル
シウムカーバイドを用いた場合においても大部分
のカルシウムカーバイドは未反応の状態で溶銑表
面へ浮上する。この溶銑表面へ浮上した未反応の
カルシウムカーバイドは溶銑表面に浮遊する溶融
スラグと混合され溶銑との接触が悪くなると共に
前記溶融スラグあるいは溶銑表面上の雰囲気中に
含まれる酸素、二酸化炭素等の酸化性ガスによつ
て容易に酸化されて生石灰となるため、ほとんど
脱硫に寄与しない。
一方、脱硫処理前に溶銑表面に浮遊する溶融ス
ラグを出来る限り除去することにより溶銑表面に
浮上したカルシウムカーバイドが前記溶融スラグ
と混合され溶銑との接触が悪くなると共に酸化さ
れるのを防ぐ方法があるが、溶融スラグを除去す
る設備が必要になると共に除去作用による鉄ロス
が大きい。またカルシウムカーバイドを炭素等の
還元性の物質との混合物を溶銑中に吹き込む方法
あるいは天然ガス等の還元性ガスを搬送ガスとす
る方法があるがその効果は充分でない。
さらに、本発明者等は溶銑表面を実質的に非酸
化性にすると共に、予め生石灰を溶銑内に吹き込
み溶融スラグを半固化あるいは固化した後カルシ
ウムカーバイドを吹き込む溶銑の脱硫方法を発明
し特願昭53−89319号で特許出願した。しかしな
がら、この脱硫方法により溶銑内に吹き込まれた
カルシウムカーバイドの脱硫反応効率をある程度
高めることができたがその効果は充分でなく、脱
硫処理後のスラグが大きな塊状になり脱硫処理後
の除滓が困難になるという欠点がある。
本発明は前述の如き粉状のカルシウムカーバイ
ドを搬送ガスと共に溶銑内へ吹き込む粉末吹込脱
硫法の有する欠点を除去、改善することのできる
溶銑の脱硫方法を提供することを目的とし、カル
シウムカーバイドを主体とする脱硫剤による脱硫
処理前に予め容器内に収納された溶銑内に浸漬し
たランスパイプを通じて窒素ガスを搬送ガスとし
て生石灰、焼成ドロマイトの何れか１種または２
種と炭素とを主体とする添加物を溶銑内に吹き込
み、溶銑表面上に浮遊する溶融スラグの大部分を
前記添加物と混合された固形物となし、前記固形
物により溶銑表面の大部分を覆うことにより、次
いで溶銑内に吹き込まれ未反応の状態で溶銑表面
に浮上するカルシウムカーバイドを溶銑表面にお
いてさらに溶銑の脱硫反応に寄与させることを特
徴とする溶銑の脱硫方法に関するものである。
以下本発明を詳細に説明する。
溶銑内へ搬送ガスと共に吹き込まれたカルシウ
ムカーバイトの一部は搬送ガスの気泡と共に溶銑
表面へ浮上する過程において溶銑と接触し溶銑中
の硫黄と反応するが、前記カルシウムカーバイド
の大部分は搬送ガスの気泡内に閉じ込められて溶
銑と接触することができず未反応の状態のまま溶
銑表面へ浮上する。本発明によれば前記搬送ガス
の気泡内に閉じ込められて溶銑表面へ浮上した未
反応のカルシウムカーバイドと溶銑との接触を溶
銑表面の大部分を覆う固形物の作用により良好に
することにより前記未反応のカルシウムカーバイ
ドを脱硫反応に寄与せしめ、搬送ガスと共に吹き
込まれたカルシウムカーバイドの溶銑内部の脱硫
反応に溶銑表面の脱硫反応を加えてカルシウムカ
ーバイドの利用効率を総合的に著しく高めること
ができる。
容器内に収納された溶銑表面に浮遊する溶融ス
ラグの主成分はCaO，SiO2，Ａ2O3であり若干
量のMgO，MnO，Ｃ等をも含み前記溶融スラグ
はカルシウムカーバイドを容易に酸化するため、
溶融スラグが浮遊する溶銑内に搬送ガスと共にカ
ルシウムカーバイドを吹き込んでも、溶銑表面へ
浮上したカルシウムカーバイドはほとんど脱硫反
応に寄与することができない。
本発明者等は前記溶銑表面に浮遊する溶融スラ
グに関して詳細に検討を行ない、溶融スラグが浮
遊する溶銑内に搬送ガスと共に生石灰あるいは焼
成ドロマイトおよび炭素を吹き込むと、吹き込ま
れた生石灰あるいは焼成ドロマイトが溶融スラグ
と混合されてスラグ中のCaO濃度が増加し、しだ
いにスラグの融点が高くなり固化するが、その際
生石灰あるいは焼成ドロマイトと共に吹き込まれ
た炭素はスラグ中に分散しスラグが凝集して大き
な塊になるのを抑制し、固化されたスラグは粒径
約200mm以下の小さな塊状の固形物となつて溶銑
表面を覆うことを知見した。
また本発明者等は溶銑内に搬送ガスと共に吹き
込まれた粉状のカルシウムカーバイドの大部分は
搬送ガスの気泡と共に溶銑表面へ浮上するが、溶
銑表面に塊状の固形物が存在するとカルシウムカ
ーバイドは溶銑表面の揺動によつて溶銑表面浮上
位置から溶銑を収納する容器の外縁部へと押しや
られる過程において前記塊状の固形物と接触し、
大部分のカルシウムカーバイドは揺動する溶銑に
より再び溶銑内に巻き込まれることを知見した。
即ち容器内に収納された溶銑内に搬送ガスと共
に予め生石灰、焼成ドロマイトの何れか１種また
は２種と炭素とを主体とする添加物を吹き込み、
次いでカルシウムカーバイドを主体とする脱硫剤
を搬送ガスと共に溶銑内に吹き込む本発明の脱硫
方法によれば、予め溶銑内に吹き込まれた生石
灰、焼成ドロマイトの何れか１種または２種およ
び炭素により溶銑表面に浮遊する溶融スラグを固
化して粒径約200mm以下の小さな塊状の固形物と
することができ、次いで溶銑内に吹き込まれ搬送
ガスの気泡と共に溶銑表面に浮上する未反応のカ
ルシウムカーバイドは前記固形物の作用により溶
銑内に再び巻き込まれるため、溶銑表面浮上後に
おいても溶銑と充分に接触し脱硫反応に寄与する
ことができる。
さらに本発明の脱硫反応においては予め生石灰
あるいは焼成ドロマイトと共に溶銑内に吹き込ま
れ溶銑表面の大部分を覆う炭素により溶銑表面上
の雰囲気を非酸化性に保持することができ、次い
で溶銑内に吹き込まれるカルシウムカーバイドの
溶銑表面上の雰囲気による酸化を抑制することが
できる。
それ故本発明の脱硫方法によれば搬送ガスと共
に吹き込まれたカルシウムカーバイドは溶銑内部
の脱硫反応に溶銑表面の脱硫反応を加えてカルシ
ウムカーバイドの利用効率を総合的に著しく高め
ることができると共に脱硫処理後の除滓が容易で
ある。
一方、溶融スラグが浮遊する溶銑内に搬送ガス
と共に生石灰およびまたは焼成ドロマイトのみを
吹き込み、次いでカルシウムカーバイドを搬送ガ
スと共に溶銑内に吹き込む脱硫方法においては、
予め溶銑内に吹き込まれた生石灰あるいは焼成ド
ロマイトにより溶銑表面に浮遊する溶融スラグを
固化して固形物とすることができるが、前記固形
物は大きな塊状のものとなつて固形物が浮遊する
溶銑表面の揺動が少なくなり、次いで溶銑内に吹
き込まれ搬送ガスの気泡と共に溶銑表面に浮上す
る未反応のカルシウムカーバイドを溶銑内に巻き
込ませる力が弱くなつて、前記カルシウムカーバ
イドと溶銑との接触が悪くなるため脱硫反応を充
分促進することができないと共に、脱硫処理後の
除滓が困難になる。
また、予め生石灰、焼成ドロマイトの何れか１
種または２種および炭素を溶銑内へ搬送ガスと共
に吹き込むことなしに溶銑表面へ添加する方法に
おいては、生石灰およびまたは焼成ドロマイトと
炭素が溶融スラグと充分に混合されず大部分の溶
融スラグを固化することが困難であるため生石灰
およびまたは焼成ドロマイトと炭素は搬送ガスと
共に溶銑内に吹き込む必要がある。
尚、溶銑表面に浮遊する溶融スラグを固化させ
るために必要な生石灰およびまたは焼成ドロマイ
トの吹込量は溶銑表面に浮遊する溶融スラグの
量、組成および温度によつて変化する。前述の如
く溶銑表面に浮遊する溶融スラグはCaO，
SiO2，Ａ2O3を主成分とし若干量のMgO，
MnO，Ｃ等を含む組成であり、本発明者等の研
究によれば、例えば溶銑表面に浮遊するCaO35
％、SiO240％、Ａ2O315％、MgO3％、MnO3
％、C2％、その他２％の組成の温度1400℃の溶
融スラグ1tを固化させるためには300Kg以上の生
石灰あるいは500Kg以上の焼成ドロマイトを、
CaO40％、SiO235％、Ａ2O315％、MgO5％、
MnO1％、C2％、その他２％の組成の温度1400℃
の溶融スラグ1tを固化させるためには250Kg以上
の生石灰あるいは400Kg以上の焼成ドロマイトを
溶銑中に吹き込む必要がある。
本発明の脱硫方法において溶銑表面へ未反応の
状態で浮上するカルシウムカーバイドの大部分を
溶銑表面に浮遊する塊状の固形物と接触させ、激
しく揺動する溶銑により再び溶銑内に巻き込ませ
るため、大部分の溶銑表面を塊状の固形物で覆う
必要がある。大部分の溶銑表面が塊状の固形物で
覆われないと、前記固形物は次いでカルシウムカ
ーバイドと共に溶銑内に吹き込まれる搬送ガスの
気泡の上昇運動によつて起る溶銑流れにより溶銑
表面の揺動が少ない容器の外縁部へ押しやられる
ため、カルシウムカーバイドが前記固形物と接触
しても溶銑表面の揺動が少なく、カルシウムカー
バイドを再び溶銑内に巻き込ませる力が弱く、溶
銑表面における脱硫反応を促進することができな
いため、大部分の溶銑表面を前記固形物で覆う必
要がある。従つて脱硫処理前に溶銑表面に浮遊す
る溶融スラグが少ない場合には前記溶融スラグを
固化させるのに必要な生石灰およびまたは焼成ド
ロマイトの量以上を溶銑内に吹き込み、溶銑表面
の大部分を固形物で覆う必要がある。
ところで本発明の脱硫方法においてカルシウム
カーバイドを主体とする脱硫剤を溶銑内に吹き込
む方法は予め生石灰、焼成ドロマイトの何れか１
種または２種と炭素とを主体とする添加物を溶銑
内に吹き込み、次いで搬送ガスのみを溶銑内に吹
き込んだ後、搬送ガスと共にカルシウムカーバイ
ドを主体とする脱硫剤を溶銑内に吹き込んでもよ
く、予め溶銑内に吹き込まれる生石灰、焼成ドロ
マイトの何れか１種または２種と炭素とを主体と
する添加物とカルシウムカーバイドを主体とする
脱硫剤の一部を同時に吹き込んでもよい。
本発明の脱硫方法においてカルシウムカーバイ
ドを主体とする脱硫剤を吹き込む前に生石灰、焼
成ドロマイトの何れか１種または２種と炭素とを
主体とする添加物を吹き込むことを特徴とする
が、前記生石灰およびまたは焼成ドロマイトのう
ち溶融スラグを固化させるのに必要な使用量なら
びに価格の点から生石灰が最も好ましく、また前
記炭素はコークス、木炭、黒鉛、カーボンブラツ
クあるいはフエノール樹脂等の高炭素含有有機化
合物樹脂などのＣを主成分とする物質を用いるこ
とが価格の点から最も好ましい。
また予め溶銑内に搬送ガスと共に吹き込む生石
灰と炭素との重量比は生石灰100重量部に対し炭
素が５重量部未満では溶銑表面上に浮遊する溶融
スラグが凝集し大きな塊になるのを充分に抑制で
きないと共に溶銑表面を充分に非酸化性に保持す
ることができず、20重量部を超えると添加する炭
素の量が多くなつて脱硫処理費が高くなるため５
〜20重量部にすることが望ましい。
さらに、カルシウムカーバイドを主体とする脱
硫剤としてはカルシウムカーバイドの酸化を防止
する上から熱分解して二酸化炭素、水蒸気等の酸
化性ガスを発生する物質を含まない脱硫剤が望ま
しく、特にカルシウムカーバイド100重量部と石
灰窒素10〜100重量部との混合脱硫剤は石灰窒素
が熱分解して発生するガスにより脱硫剤周囲の溶
銑を撹拌することができ、溶銑表面をさらに非酸
化性にすることができるので有利である。カルシ
ウムカーバイド100重量部に対し石灰窒素が10重
量部より少ないと石灰窒素が熱分解して発生する
ガス量が充分でなく、100重量部より多いと脱硫
剤に含まれるカルシウムカーバイドの量が少なく
なつて脱硫効果が小さくなるためカルシウムカー
バイド100重量部に対し石灰窒素は10〜100重量部
であることが好ましい。
次に本発明を実施例について比較例と対比して
具体的に説明する。
実施例ならびに比較例
混銑車内に収納した約80tの硫黄濃度約0.04％
の高炉溶銑内に耐火性ランスパイプを通じて窒素
ガスと共に粒径0.2mm以下のカルシウムカーバイ
ドあるいはカルシウムカーバイドと石灰窒素との
混合物を吹き込み脱硫処理した。尚前記溶銑表面
には0.3〜0.5tの溶融スラグが浮遊しており、溶
銑温度は1350〜1400℃であつた。表に脱硫処理し
た結果を示す。
前記表において生石灰、焼成ドロマイト、石油
コークス吹込量は溶銑内へカルシウムカーバイド
を吹き込む前に予め溶銑内に吹き込まれた生石
灰、焼成ドロマイト、石油コークスの吹込量、
（石油コークス／生石灰）は前記溶銑内へ吹き込
まれた石油コークスの生石灰に対する重量比、溶
銑表面の状態は生石灰、焼成ドロマイト、石油コ
ークス吹込後の溶銑表面の状態を示し、脱硫剤Ａ
はカルシウムカーバイド単味脱硫剤、脱硫剤Ｂは
カルシウムカーバイド100重量部と石灰窒素20重
量部との混合脱硫剤、脱硫剤Ｃはカルシウムカー
バイド100重量部と石灰窒素60重量部との混合脱
硫剤であり、脱硫剤原単位は溶銑1tにつき添加し
た前記脱硫剤の重量をKgで表わした値、脱硫率は
溶銑の脱硫処理前の硫黄濃度をS1％、脱硫処理後
の硫黄濃度をS2％とする時（S1‐S2）／S1の百分
率でもつて表わした値である。
The present invention relates to a hot metal desulfurization method in which powdered calcium carbide is injected together with a carrier gas through a lance pipe immersed in hot metal stored in a container. This invention relates to a method for desulfurizing hot metal, in which a desulfurizing agent mainly consisting of calcium carbide is injected into the hot metal after additives mainly consisting of two kinds of carbon and carbon are injected into the hot metal. In recent years, due to the development of new steel products and higher quality requirements, the demand for low sulfur steel with a sulfur content of around 0.015% and ultra-low sulfur steel with a sulfur content of around 0.005% has increased.
At the same time, the sulfur content in hot metal is increasing due to the high efficiency operation of blast furnaces and raw material conditions.
Ex-furnace desulfurization of hot metal has become an essential requirement for today's steel plants. Ex-furnace desulfurization of hot metal has been extensively researched for a long time, and the commonly used ex-furnace desulfurization methods for hot metal include powder injection method using calcium carbide, soda ash, quicklime, etc., gas injection stirring method, impeller stirring method, and rocking method. The ladle method and the rotating drum method are known, but at present, the powder blowing method using a desulfurizing agent mainly composed of calcium carbide and the impeller stirring method have been widely adopted after various processes. However, in the desulfurization treatment using the powder blowing method and the impeller stirring method, the utilization efficiency of calcium carbide is low at 15-30%, and the remaining 85-30%
70% of the calcium carbide does not react with the sulfur in the hot metal and is completely lost. The price of calcium carbide has skyrocketed due to the large increase in electricity rates following the recent oil crisis, and improving the efficiency of calcium carbide use in the desulfurization process of hot metal is a major challenge for the steel industry in terms of reducing the cost of steel. This is one of the challenges. The powder blowing method is a method in which a powdered desulfurizing agent such as calcium carbide or quicklime is blown into the hot metal through a lance pipe immersed in the lower part of the hot metal along with a carrier gas such as nitrogen gas to bring the hot metal into sufficient contact with the desulfurizing agent. In this method, the particle size of the desulfurizing agent can be made extremely small to 20 to 30 microns, and the surface area of the desulfurizing agent itself is extremely large. However, most of the desulfurization agent blown into the hot metal with the carrier gas cannot escape from the bubbles of the carrier gas and is trapped within the bubbles and cannot come into contact with the hot metal. Because the floating speed of the desulfurizing agent is fast and the time it is in contact with the hot metal is quite short, only a few seconds, the desulfurizing agent blown into the hot metal cannot make sufficient contact with the hot metal during the floating process, and most of it remains unused. It floats to the surface of hot metal in a reactive state. That is, even when calcium carbide, which easily reacts with sulfur, is used as a desulfurizing agent, most of the calcium carbide floats to the surface of the hot metal in an unreacted state. The unreacted calcium carbide floating on the surface of the hot metal mixes with the molten slag floating on the surface of the hot metal, resulting in poor contact with the hot metal and oxidation of oxygen, carbon dioxide, etc. contained in the molten slag or the atmosphere on the surface of the hot metal. It is easily oxidized by toxic gases and becomes quicklime, so it hardly contributes to desulfurization. On the other hand, there is a method of removing as much of the molten slag floating on the surface of the hot metal as possible before desulfurization treatment to prevent calcium carbide floating on the surface of the hot metal from being mixed with the molten slag, resulting in poor contact with the hot metal and being oxidized. However, equipment to remove the molten slag is required, and iron loss due to the removal process is large. Furthermore, there are methods in which a mixture of calcium carbide and a reducing substance such as carbon is blown into hot metal, or a method in which a reducing gas such as natural gas is used as a carrier gas, but these methods are not sufficiently effective. Furthermore, the present inventors have invented a method for desulfurizing hot metal, in which the surface of the hot metal is made substantially non-oxidizing, and calcium carbide is injected after the molten slag is semi-solidified or solidified by injecting quicklime into the hot metal. A patent application was filed under No. 53-89319. However, although this desulfurization method was able to increase the desulfurization reaction efficiency of calcium carbide blown into the hot metal to some extent, the effect was not sufficient, and the slag after the desulfurization treatment became large lumps, making it difficult to remove the slag after the desulfurization treatment. The disadvantage is that it is difficult. The purpose of the present invention is to provide a hot metal desulfurization method that can eliminate and improve the drawbacks of the powder injection desulfurization method in which powdered calcium carbide is blown into hot metal together with a carrier gas. Before desulfurization treatment with a desulfurization agent, nitrogen gas is used as a carrier gas through a lance pipe immersed in hot metal stored in a container in advance, and either one or two of quicklime and calcined dolomite are used as a carrier gas.
Additives mainly consisting of seeds and carbon are blown into the hot metal, and most of the molten slag floating on the surface of the hot metal is made into solids mixed with the additives, and the solids cover most of the surface of the hot metal. The present invention relates to a hot metal desulfurization method characterized in that by covering the hot metal, calcium carbide that is then blown into the hot metal and floats to the surface of the hot metal in an unreacted state is made to further contribute to the desulfurization reaction of the hot metal on the surface of the hot metal. The present invention will be explained in detail below. A part of the calcium carbide blown into the hot metal together with the carrier gas comes into contact with the hot metal during the process of floating to the surface of the hot metal with the bubbles of the carrier gas and reacts with the sulfur in the hot metal, but most of the calcium carbide is blown into the carrier gas. It is trapped in the bubbles and cannot come into contact with the hot metal, so it floats to the surface of the hot metal in an unreacted state. According to the present invention, the unreacted calcium carbide trapped in the carrier gas bubbles and floated to the surface of the hot metal is made to have good contact with the hot metal by the action of the solid that covers most of the surface of the hot metal. By making the reactive calcium carbide contribute to the desulfurization reaction, and adding the desulfurization reaction on the surface of the hot metal to the desulfurization reaction inside the hot metal of the calcium carbide blown in with the carrier gas, it is possible to significantly improve the utilization efficiency of calcium carbide overall. The main components of the molten slag floating on the surface of the hot metal stored in the container are CaO, SiO 2 and A 2 O 3 and also contain small amounts of MgO, MnO, C, etc. The molten slag easily oxidizes calcium carbide. In order to
Even if calcium carbide is blown together with a carrier gas into hot metal in which molten slag floats, the calcium carbide that has floated to the surface of the hot metal can hardly contribute to the desulfurization reaction. The present inventors conducted a detailed study on the molten slag floating on the surface of the hot metal, and found that when quicklime or calcined dolomite and carbon are blown into the molten pig iron in which the molten slag is floating, along with a carrier gas, the blown quicklime or calcined dolomite melts. When mixed with slag, the concentration of CaO in the slag increases, and the melting point of the slag gradually increases, causing it to solidify.At this time, the carbon blown in with quicklime or calcined dolomite is dispersed in the slag, and the slag aggregates into large lumps. It was discovered that the solidified slag becomes small lump-like solids with a particle size of about 200 mm or less and covers the surface of the hot metal. In addition, the present inventors have found that most of the powdered calcium carbide blown into the hot metal together with the carrier gas floats to the surface of the hot metal along with the bubbles of the carrier gas, but if there are lumpy solids on the surface of the hot metal, the calcium carbide Contact with the lump-like solids in the process of being pushed from the surface floating position of the hot metal to the outer edge of the container storing the hot metal by the rocking of the surface,
It was found that most of the calcium carbide was re-engulfed into the hot metal by the shaking of the hot metal. That is, additives mainly consisting of one or two of quicklime and calcined dolomite and carbon are blown into hot metal stored in a container together with a carrier gas,
Next, according to the desulfurization method of the present invention in which a desulfurization agent mainly composed of calcium carbide is blown into the hot metal together with a carrier gas, the surface of the hot metal is reduced by one or both of quicklime and calcined dolomite and carbon that have been blown into the hot metal in advance. The molten slag floating in the slag can be solidified into small lump-like solids with a particle size of about 200 mm or less, and the unreacted calcium carbide that is blown into the hot metal and floats to the surface of the hot metal along with the bubbles of the carrier gas becomes the solid. Since it is re-engulfed into the hot metal by the action of the object, it can sufficiently contact the hot metal and contribute to the desulfurization reaction even after it floats to the surface of the hot metal. Furthermore, in the desulfurization reaction of the present invention, the atmosphere on the surface of the hot metal can be kept non-oxidizing by the carbon that is blown into the hot metal together with quicklime or calcined dolomite and covers most of the surface of the hot metal. Oxidation of calcium carbide caused by the atmosphere on the surface of hot metal can be suppressed. Therefore, according to the desulfurization method of the present invention, the calcium carbide blown together with the carrier gas can add the desulfurization reaction on the surface of the hot metal to the desulfurization reaction inside the hot metal, thereby significantly increasing the utilization efficiency of calcium carbide overall, and also in the desulfurization process. It is easy to remove the slag afterwards. On the other hand, in a desulfurization method in which only quicklime and/or calcined dolomite are blown into the hot metal in which molten slag is floating, along with a carrier gas, and then calcium carbide is blown into the hot metal along with the carrier gas.
The molten slag floating on the surface of the hot metal can be solidified into a solid by quicklime or calcined dolomite that is blown into the hot metal in advance. As a result, the force that draws unreacted calcium carbide, which is then blown into the hot metal and floats to the surface of the hot metal along with the bubbles of the carrier gas, into the hot metal becomes weaker, resulting in poor contact between the calcium carbide and the hot metal. Therefore, the desulfurization reaction cannot be sufficiently promoted, and it becomes difficult to remove the slag after the desulfurization treatment. In addition, either quicklime or calcined dolomite can be prepared in advance.
In the method of adding a seed or two and carbon to the hot metal surface without blowing into the hot metal together with a carrier gas, the quicklime and/or calcined dolomite and carbon are not sufficiently mixed with the molten slag and solidify most of the molten slag. Since this is difficult, quicklime and/or calcined dolomite and carbon must be blown into the hot metal together with a carrier gas. The amount of quicklime and/or calcined dolomite required to solidify the molten slag floating on the surface of the hot metal varies depending on the amount, composition, and temperature of the molten slag floating on the surface of the hot metal. As mentioned above, the molten slag floating on the surface of hot metal is CaO,
The main components are SiO 2 and A 2 O 3 , with a small amount of MgO,
The composition includes MnO, C, etc., and according to the research of the present inventors, for example, CaO35 floating on the surface of hot metal
%, SiO 2 40%, A 2 O 3 15%, MgO3%, MnO3
%, C2%, and other 2% at a temperature of 1400°C, requires at least 300 kg of quicklime or over 500 kg of calcined dolomite.
CaO 40%, SiO 2 35%, A 2 O 3 15%, MgO 5%,
Temperature of 1400℃ with composition of MnO1%, C2%, and other 2%
In order to solidify 1 ton of molten slag, it is necessary to blow over 250 kg of quicklime or over 400 kg of calcined dolomite into the hot metal. In the desulfurization method of the present invention, most of the calcium carbide that floats to the surface of the hot metal in an unreacted state is brought into contact with the lumpy solids floating on the surface of the hot metal, and is rolled up into the hot metal again by the violently shaking hot metal. It is necessary to cover the surface of the molten pig iron with lumpy solids. If most of the hot metal surface is not covered with lumpy solids, the solids will then cause the hot metal surface to oscillate due to the hot metal flow caused by the upward movement of the carrier gas bubbles that are blown into the hot metal with calcium carbide. Since the calcium carbide is pushed to the outer edge of the container, even when the calcium carbide comes into contact with the solid matter, there is less shaking of the hot metal surface, and the force that draws the calcium carbide into the hot metal again is weak, promoting the desulfurization reaction on the hot metal surface. Therefore, it is necessary to cover most of the surface of the hot metal with the solid material. Therefore, if there is little molten slag floating on the surface of the hot metal before desulfurization treatment, more quicklime and/or calcined dolomite than is necessary to solidify the molten slag is blown into the hot metal to cover most of the surface of the hot metal with solids. It needs to be covered with. By the way, in the desulfurization method of the present invention, the desulfurization agent mainly composed of calcium carbide is injected into the hot metal in advance by adding either quicklime or calcined dolomite.
Additives mainly consisting of a seed or two and carbon may be blown into the hot metal, then only a carrier gas may be blown into the hot metal, and then a desulfurization agent mainly consisting of calcium carbide may be blown into the hot metal together with the carrier gas. One or both of quicklime and calcined dolomite, an additive mainly composed of carbon, and a part of a desulfurization agent mainly composed of calcium carbide may be simultaneously blown into the hot metal in advance. The desulfurization method of the present invention is characterized in that before injecting the desulfurization agent mainly composed of calcium carbide, an additive mainly composed of one or two of quicklime and calcined dolomite and carbon is injected into the desulfurization agent. and or calcined dolomite, quicklime is most preferred from the viewpoint of cost and the amount required to solidify the molten slag, and the carbon is coke, charcoal, graphite, carbon black, or a high carbon-containing organic compound resin such as phenolic resin. From the viewpoint of cost, it is most preferable to use a substance containing C as a main component. In addition, if the weight ratio of quicklime and carbon that is blown into the hot metal in advance together with the carrier gas is less than 5 parts by weight for every 100 parts by weight of quicklime, it will sufficiently suppress the molten slag floating on the surface of the hot metal from agglomerating into large lumps. It is not possible to maintain the hot metal surface sufficiently non-oxidizing, and if it exceeds 20 parts by weight, the amount of carbon added increases and the desulfurization treatment cost increases.
It is desirable that the amount is ~20 parts by weight. Furthermore, as a desulfurizing agent mainly composed of calcium carbide, in order to prevent oxidation of calcium carbide, desulfurizing agents that do not contain substances that thermally decompose and generate oxidizing gases such as carbon dioxide and water vapor are desirable, especially calcium carbide 100 A mixed desulfurizing agent containing 10 to 100 parts by weight of lime nitrogen and lime nitrogen can stir the hot metal around the desulfurizing agent with the gas generated by thermal decomposition of lime nitrogen, making the surface of the hot metal more non-oxidizing. It is advantageous because it can be done. If the amount of lime nitrogen is less than 10 parts by weight per 100 parts by weight of calcium carbide, the amount of gas generated by thermal decomposition of lime nitrogen will not be sufficient, and if it is more than 100 parts by weight, the amount of calcium carbide contained in the desulfurization agent will decrease. Therefore, the amount of lime nitrogen is preferably 10 to 100 parts by weight per 100 parts by weight of calcium carbide. Next, the present invention will be specifically described in terms of Examples and in comparison with Comparative Examples. Examples and comparative examples Approximately 80 tons of sulfur concentration approximately 0.04% stored in a pig iron mixing car
Desulfurization treatment was carried out by injecting calcium carbide or a mixture of calcium carbide and lime nitrogen with a particle size of 0.2 mm or less together with nitrogen gas into the hot metal of a blast furnace through a refractory lance pipe. Note that 0.3 to 0.5 tons of molten slag was floating on the surface of the hot metal, and the temperature of the hot metal was 1350 to 1400°C. The table shows the results of desulfurization treatment. In the table above, the amount of quicklime, calcined dolomite, and petroleum coke blown into the hot metal is the amount of quicklime, calcined dolomite, and petroleum coke that was blown into the hot metal before calcium carbide was blown into the hot metal.
(Petroleum coke/quicklime) indicates the weight ratio of petroleum coke to quicklime blown into the hot metal, and the condition of the hot metal surface indicates quicklime, calcined dolomite, and the condition of the hot metal surface after petroleum coke is blown into the hot metal.
Desulfurization agent is a single desulfurization agent made of calcium carbide, desulfurization agent B is a mixed desulfurization agent containing 100 parts by weight of calcium carbide and 20 parts by weight of lime nitrogen, and desulfurization agent C is a mixed desulfurization agent containing 100 parts by weight of calcium carbide and 60 parts by weight of lime nitrogen. Yes, the desulfurization agent unit is the weight of the desulfurization agent added per 1 ton of hot metal expressed in kg, and the desulfurization rate is the sulfur concentration of hot metal before desulfurization treatment, S 1 %, and the sulfur concentration after desulfurization treatment, S 2 %. It is also a value expressed as a percentage of (S 1 - S 2 )/S 1 when .
【表】
前記表より溶銑表面に溶融スラグが浮遊する状
態で溶銑内へ脱硫剤を吹き込んだ脱硫No.1，２
に比べ、予め溶銑内へ生石灰を吹き込み溶銑表面
に浮遊する溶融スラグを固化した後溶銑内へ脱硫
剤を吹き込んだ脱硫No.3，４は脱硫率がわずか
に高くなつているだけであるが、本発明の脱硫方
法である予め溶銑内への生石灰あるいは焼成ドロ
マイトと石油コークスとを吹き込み溶銑表面に浮
遊する溶融スラグを固化した後溶銑内へ脱硫剤を
吹き込んだ脱硫No.5〜13は脱硫率が76％以上と
かなり高くなつており、前記生石灰100重量部に
対する前記石油コークスが５重量部以上において
は脱硫率が82％以上と著しく高いことがわかる。
尚脱硫No.3，４においては脱硫処理後の除滓
が困難であつたが、本発明の脱硫方法による脱硫
No.5〜13においては脱硫処理後の除滓は通常通
り行なうことができた。
以上の如く本発明の脱硫方法によれば搬送ガス
と共に溶銑内に吹き込まれ未反応の状態で溶銑表
面に浮上したカルシウムカーバイドが溶銑表面に
浮遊する溶融スラグあるいは溶銑表面上の雰囲気
により酸化されるのを抑えると共に、溶銑表面に
固形物を存在させて前記未反応のカルシウムカー
バイドと溶銑との接触を充分にすることにより、
カルシウムカーバイドを主体とする脱硫剤の利用
効率を著しく高めることができる。[Table] From the above table, desulfurization No. 1 and 2 in which the desulfurization agent was injected into the hot metal with molten slag floating on the surface of the hot metal
Compared to this, desulfurization Nos. 3 and 4, in which quicklime was injected into the hot metal in advance to solidify the molten slag floating on the surface of the hot metal, and then a desulfurization agent was injected into the hot metal, had only a slightly higher desulfurization rate. In the desulfurization method of the present invention, quicklime or calcined dolomite and petroleum coke are injected into the hot metal in advance to solidify the molten slag floating on the surface of the hot metal, and then a desulfurization agent is injected into the hot metal. is considerably high at 76% or more, and it can be seen that when the petroleum coke is 5 parts by weight or more based on 100 parts by weight of quicklime, the desulfurization rate is extremely high at 82% or more. In desulfurization Nos. 3 and 4, it was difficult to remove slag after desulfurization treatment, but desulfurization by the desulfurization method of the present invention
In Nos. 5 to 13, slag removal after desulfurization treatment could be carried out as usual. As described above, according to the desulfurization method of the present invention, the calcium carbide that is blown into the hot metal together with the carrier gas and floats to the surface of the hot metal in an unreacted state is oxidized by the molten slag floating on the surface of the hot metal or the atmosphere on the surface of the hot metal. By suppressing the molten metal and by making solid matter exist on the surface of the hot metal to ensure sufficient contact between the unreacted calcium carbide and the hot metal,
The utilization efficiency of desulfurizing agents mainly composed of calcium carbide can be significantly increased.
Claims (1)
パイプを通じて窒素ガスを搬送ガスとして粉状の
生石灰、焼成ドロマイトの何れか１種または２種
と炭素とを主体とする添加物を溶銑内に吹き込
み、溶銑表面上に浮遊する溶融スラグの大部分を
前記添加物が混合された固形物となし、前記固形
物により溶銑表面の大部分を覆い、次いで前記ラ
ンスパイプを通じて窒素ガスを搬送ガスとして粉
状のカルシウムカーバイドを主体とする脱硫剤を
溶銑内に吹き込むことを特徴とする溶銑の脱硫方
法。 ２ 前記添加物は生石灰100重量部に対し炭素５
〜20重量部を含有する特許請求の範囲第１項記載
の方法。 ３ 前記脱硫剤はカルシウムカーバイド100重量
部に対し石灰窒素10〜100重量部を含有する特許
請求の範囲第１あるいは２項記載の方法。[Claims] 1. Addition mainly consisting of one or two of powdered quicklime and calcined dolomite and carbon using nitrogen gas as a carrier gas through a lance pipe immersed in hot metal stored in a container. is blown into the hot metal, most of the molten slag floating on the surface of the hot metal becomes a solid mixed with the additive, most of the surface of the hot metal is covered with the solid, and then nitrogen gas is blown into the hot metal through the lance pipe. A method for desulfurizing hot metal, which is characterized by injecting a desulfurizing agent mainly consisting of powdered calcium carbide into the hot metal using as a carrier gas. 2 The above additive is carbon 5 per 100 parts by weight of quicklime.
20. The method of claim 1 containing .about.20 parts by weight. 3. The method according to claim 1 or 2, wherein the desulfurizing agent contains 10 to 100 parts by weight of lime nitrogen per 100 parts by weight of calcium carbide.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13303978A JPS5562109A (en) | 1978-10-28 | 1978-10-28 | Desulfurizing method for molten pig iron |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13303978A JPS5562109A (en) | 1978-10-28 | 1978-10-28 | Desulfurizing method for molten pig iron |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5562109A JPS5562109A (en) | 1980-05-10 |
| JPS6125763B2 true JPS6125763B2 (en) | 1986-06-17 |
Family
ID=15095374
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP13303978A Granted JPS5562109A (en) | 1978-10-28 | 1978-10-28 | Desulfurizing method for molten pig iron |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5562109A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0324034Y2 (en) * | 1985-10-01 | 1991-05-24 | ||
| JPH0445501Y2 (en) * | 1988-09-07 | 1992-10-26 |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100862799B1 (en) * | 2002-08-02 | 2008-10-13 | 주식회사 포스코 | Method for Preventing Slag Inclusion in Converter Steel Tapping |
-
1978
- 1978-10-28 JP JP13303978A patent/JPS5562109A/en active Granted
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0324034Y2 (en) * | 1985-10-01 | 1991-05-24 | ||
| JPH0445501Y2 (en) * | 1988-09-07 | 1992-10-26 |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5562109A (en) | 1980-05-10 |
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