JPS6213405B2 - - Google Patents
Info
- Publication number
- JPS6213405B2 JPS6213405B2 JP58087296A JP8729683A JPS6213405B2 JP S6213405 B2 JPS6213405 B2 JP S6213405B2 JP 58087296 A JP58087296 A JP 58087296A JP 8729683 A JP8729683 A JP 8729683A JP S6213405 B2 JPS6213405 B2 JP S6213405B2
- Authority
- JP
- Japan
- Prior art keywords
- hot metal
- oxygen
- chromium
- weight
- blowing
- 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 96
- 239000002184 metal Substances 0.000 claims description 96
- 239000011651 chromium Substances 0.000 claims description 64
- 238000007664 blowing Methods 0.000 claims description 63
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 62
- 239000001301 oxygen Substances 0.000 claims description 62
- 229910052760 oxygen Inorganic materials 0.000 claims description 62
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 57
- 229910052804 chromium Inorganic materials 0.000 claims description 57
- 238000007670 refining Methods 0.000 claims description 40
- 239000002893 slag Substances 0.000 claims description 34
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 claims description 31
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 30
- 229910001882 dioxygen Inorganic materials 0.000 claims description 30
- 238000000034 method Methods 0.000 claims description 30
- 238000003723 Smelting Methods 0.000 claims description 25
- 239000007789 gas Substances 0.000 claims description 24
- 229910000831 Steel Inorganic materials 0.000 claims description 21
- 239000010959 steel Substances 0.000 claims description 21
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 20
- 229910052799 carbon Inorganic materials 0.000 claims description 20
- 230000004907 flux Effects 0.000 claims description 20
- 238000003756 stirring Methods 0.000 claims description 17
- 238000005261 decarburization Methods 0.000 claims description 15
- 238000004519 manufacturing process Methods 0.000 claims description 13
- 150000004649 carbonic acid derivatives Chemical class 0.000 claims description 11
- 239000002994 raw material Substances 0.000 claims description 11
- 238000007599 discharging Methods 0.000 claims description 7
- 230000001590 oxidative effect Effects 0.000 claims description 7
- FUJCRWPEOMXPAD-UHFFFAOYSA-N lithium oxide Chemical class [Li+].[Li+].[O-2] FUJCRWPEOMXPAD-UHFFFAOYSA-N 0.000 claims description 6
- 229910001947 lithium oxide Inorganic materials 0.000 claims description 6
- 239000007858 starting material Substances 0.000 claims description 6
- 229910001617 alkaline earth metal chloride Inorganic materials 0.000 claims description 5
- 229910001618 alkaline earth metal fluoride Inorganic materials 0.000 claims description 5
- 229910000287 alkaline earth metal oxide Inorganic materials 0.000 claims description 5
- 150000001805 chlorine compounds Chemical class 0.000 claims description 5
- 229910000480 nickel oxide Inorganic materials 0.000 claims description 5
- GNRSAWUEBMWBQH-UHFFFAOYSA-N oxonickel Chemical compound [Ni]=O GNRSAWUEBMWBQH-UHFFFAOYSA-N 0.000 claims description 5
- 238000010438 heat treatment Methods 0.000 claims description 4
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 12
- 239000000203 mixture Substances 0.000 description 11
- 229910001220 stainless steel Inorganic materials 0.000 description 9
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 7
- 235000011941 Tilia x europaea Nutrition 0.000 description 7
- 239000004571 lime Substances 0.000 description 7
- 239000010935 stainless steel Substances 0.000 description 7
- 229910052786 argon Inorganic materials 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 6
- 238000006722 reduction reaction Methods 0.000 description 4
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 3
- 239000000571 coke Substances 0.000 description 3
- 239000010436 fluorite Substances 0.000 description 3
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 description 3
- 229910052808 lithium carbonate Inorganic materials 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 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
- 238000007796 conventional method Methods 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 230000001351 cycling effect Effects 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
- 239000011261 inert gas Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 229910052698 phosphorus Inorganic materials 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- 229910000604 Ferrochrome Inorganic materials 0.000 description 1
- 229910000519 Ferrosilicon Inorganic materials 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 229910000805 Pig iron Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000002730 additional effect Effects 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000000112 cooling gas Substances 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 239000011574 phosphorus Substances 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
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/005—Manufacture of stainless steel
-
- 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
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
-
- 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
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/068—Decarburising
- C21C7/0685—Decarburising of stainless steel
Description
本発明は、含クロム鋼とくにステンレス鋼を製
造（溶製）するさいの出発材料として、Ｐが比較
的多量に含まれている含クロム溶銑を使用して
も、これを有利に脱Ｐしながら低Ｐステンレス鋼
を製造する方法に関するものである。
鋼中のＰ（りん）は、特別の場合を除いて有害
に作用することが多く、とくに、ステンレス鋼に
あつては熱間割れ性や応力腐食割れ性などを助長
する作用を示すことがよく知られている。しかし
Crを含有した溶銑からＰを除くことは、普通鋼
に比べて難しく、実操業上はＰ含有量の少ない原
料を厳選して低Ｐ含クロム溶銑を作りこれを脱炭
精錬に供しているのが通常であつた。
本発明は、従来法では使用できなかつたような
含Ｐ原料でも含クロム鋼製造原料に供し得る新し
い含クロム鋼精錬法の開発を目的としてなされた
ものである。この目的において、本発明者らは、
既に同一出願人に係る特開昭56―5910号公報に提
案された含クロム溶銑用の脱Ｐ用フラツクスを実
操業的にどのように使用した場合に含クロム溶銑
から低Ｐクロム溶鋼を有利に精錬できるかについ
て、嫁動設備規模での種々の試験研究を重ねた結
果、ここに、高Ｐ含クロム溶銑から低Ｐクロム鋼
を製造する新しい精錬法を確立することができ
た。
本発明に従う高Ｐ含クロム溶銑から低Ｐクロム
鋼を製造する精錬法は、Crを３重量％以上含有
する含クロム溶銑を出発材料に用いて含クロム鋼
を精錬するにあたり、その脱炭精錬前において、
炉底に酸素系ガスおよび非酸素系ガスを同時に若
しくは選択的に吹込可能な二重管羽口を有しかつ
酸素上吹可能な精錬炉に該含クロム溶銑を入れ、
以下の工程、即ち、
第一工程の吹錬終了後のＣ含有量が4.5重量％
以上となるに十分な量の炭素源をこの精錬炉内含
クロム溶銑に添加した上でまたは添加しながら炉
底より非酸素系ガスを供給して該溶銑を撹拌しつ
つSiが0.15重量％以下になるまで酸素底吹き吹錬
もしくは酸素上底吹き吹錬を実施しついで排滓す
る第一工程と、
脱Ｐ用フラツクスを第一工程終了後の溶銑に添
加した上でまたは添加しながら炉底より非酸素系
ガスを供給して該溶銑を強撹拌し、スラグと溶銑
を強制的に接触させた後排滓する第二工程と、
からなる予備脱Ｐ処理を予め実施し、
次いで、得られた低Ｐ含クロム溶銑をこの精錬
炉またはこの精錬炉とほかの精錬炉との組合せで
所望の炭素値まで脱炭精錬することを特徴とする
ものである。
また、この精錬法における予備脱Ｐ処理の第二
工程は、
脱Ｐ用フラツクスを第一工程終了後の溶銑に添加
した上でまたは添加しながら炉底より非酸素系ガ
スを供給して該溶銑を強撹拌し、スラグと溶銑を
強制的に接触させた後排滓する段階と、炭素源、
Si源もしくはこれに類する酸化発熱原料を溶銑に
添加してまたは添加せずして酸素を底吹きもしく
は酸素を上底吹きすることからなる溶銑の昇温段
階と、を目標Ｐ含有量に脱Ｐされるまで繰り返す
ことからなるサイクル工程で置き換えることがで
きるし、
さらには、脱Ｐ用フラツクスを第一工程終了後
の溶銑に添加した上でまたは添加しながら炉底よ
り非酸素系ガスを供給して該溶銑を強撹拌しつつ
酸素を上吹きした後排滓する改良第二工程で置き
換えてもよく、
また、脱Ｐ用フラツクスを第一工程終了後の溶
銑に添加した上でまたは添加しながら炉底より非
酸素系ガスを供給して該溶銑を強撹拌しつつ酸素
を上吹きした後排滓する段階と、炭素源、Si源も
しくはこれに類する酸化発熱原料を溶銑に添加し
てまたは添加せずして酸素を底吹きもしくは酸素
を上底吹きすることからなる溶銑の昇温段階と、
を目標Ｐ含有量に脱Ｐされるまで繰り返すことか
らなる改良サイクル工程で置き換えることもでき
る。
この本発明の精錬法に適用する脱Ｐ用フラツク
スとしては、特開昭56―5910号公報に記載された
ものが有利である。すなわち、本発明法の実施に
あたつては、脱Ｐ用フラツクスとして、アルカリ
土類金属のフツ化物、塩化物のうち１種または２
種以上が30〜80重量％と、リチウムの酸化物、炭
酸塩のうち１種または２種以上が0.4〜30重量％
と、鉄酸化物、酸化ニツケルのうち１種または２
種以上が５〜50重量％と、アルカリ土類金属の酸
化物、炭酸塩のうち１種または２種以上が０〜40
％未満と、からなるフラツクスが使用できる。
本発明は、炉底に酸素系ガスおよび非酸素系ガ
スを同時に若しくは選択的に吹込可能な二重管羽
口を有しかつ酸素上吹ランスを備えた精錬炉を用
いて実施する。このような精錬炉としては、炉底
（炉側下部も含む）に同心二重管羽口を持つ炉で
あつて且つ酸素上吹きランスを備えた上底吹き炉
が実操業上好ましい。この場合、通常は炉底の二
重管羽口の内管に純酸素もしくは酸素と非酸素系
ガスとの混合ガスを、また外管には冷却用ガスを
吹き込む吹錬操作を行うが、酸素は吹き込まずに
非酸素系ガス例えばアルゴンガス、窒素ガス、炭
化水素ガス、二酸化炭素ガス、水蒸気等の単独ま
たは混合ガスをこの羽口から湯の撹拌用に吹き込
めるような使用の仕方も出来るようにしておく。
このような精錬炉を用いることによつて本発明に
従う脱炭精錬前の予備脱Ｐ処理と脱炭精錬が共に
効果的に実施できる。すなわち含クロム溶銑の加
炭操作と脱Si反応を効果的に行わせる吹錬が実施
できると共に、これによつて得られた高Ｃ値と低
Si値の高温の溶銑に対するスラグ脱Ｐ処理を効率
よく実現させることが出来、またその後の脱炭精
錬も通常の方法に従つて困難なく行い得る。
この精錬炉による予備脱Ｐ処理の第一工程は、
含Ｐ原料を用いることによつて調達された含クロ
ム溶銑を加炭しかつ脱Siすると同時に、次工程の
脱Ｐに必要な湯温に維持または昇温する工程であ
る。脱Ｐ用フラツクスによる含クロム溶銑のスラ
グ脱Ｐを効果的に実施するには、このスラグとの
接触機会を多くすることも必要であるが、含クロ
ム溶銑中のＣ値が所定レベル以上あり（すなわち
溶銑中のＣ含有量が少なくとも4.5重量％以上あ
り）かつSiが0.2％以下、好ましくは0.15重量％
以下、の高Ｃ低Siの含クロム溶銑に対して実施す
るのが好ましくかつ溶銑温度も所定レベル以上を
維持する必要もある。本発明の第一工程はこれを
前記の精錬炉で実現させる工程である。主たる
Cr源として高炭素フエロクロムを使用する場合
には、得られる含クロム溶銑のＣ値は前記レベル
に達しないのが通常であり、またSiは特別の処理
を施さないかぎり、前記レベルより高い。第一工
程ではこのような低Ｃ高Siの含クロム溶銑を該精
錬炉に入れ、この第一工程の吹錬終了後のＣ含有
量が4.5重量％以上となるに十分な量の炭素源
（例えば粉コークスやコークス粒）をこの精錬炉
内含クロム溶銑に添加した上でまたは添加しなが
ら炉底より非酸素系ガス（例えばアルゴンガスや
窒素ガス）を供給して該溶銑を撹拌しつつSiが
0.15重量％以下になるまで酸素底吹き吹錬もしく
は酸素上底吹き吹錬を実施する。炭素源の添加は
炉頂より行つてもよいが炉底より吹き込む非酸素
系ガスに同伴して導入することもできる。溶銑に
対する加炭は吸熱反応であるが、酸素底吹き吹錬
もしくは酸素上底吹き吹錬により脱Si反応が起こ
り昇熱する。この脱Si反応は低温において脱炭反
応より優先して始まるので、この第一工程におい
ては、撹拌下での酸素底吹き吹錬もしくは酸素上
底吹き吹錬によつて、加炭、脱Si、および昇温の
スラグ脱Ｐのための三要件を同時に達成すること
ができる。なお、加炭反応は底吹きガスによる撹
拌強度が大きい程よく進行する。初期Si濃度が高
く脱Si量が多い場合には、スラグ塩基度調整のた
めに、石灰等の投入を行う必要がある。生成した
スラグはこれを排滓してこの第一工程が終了する
が、若し発熱量が不足する場合にはＣ等の酸化反
応によつて温度補償を行えばよい。
第二工程においては、前述の脱Ｐ用フラツクス
を第一工程終了後の溶銑に添加した上でまたは添
加しながら炉底より非酸素系ガスを供給して該溶
銑を強撹拌し、スラグと溶銑を強制的に接触させ
た後排滓する。この脱Ｐ用フラツクスの添加は炉
頂より行つてもよいし、炉底より吹き込むガスに
同伴して導入してもよい。そのさい、一括投入し
てもよいが、回分または連続投入したほうが効果
的である。また、炉底より吹き込む非酸素系ガス
による撹拌強度が強ければ強い程脱Ｐはよく進行
し、その流量は10Nm3／hr・ｔ以上とするのがよ
い。前記の脱Ｐ用フラツクスとして実操業的に
は、ホタル石、工業用炭酸リチウム、ミルスケー
ル、石灰等が使用しやすい。これらのフラツクス
原料は生成するスラグを汚染しないためにできる
だけ純度の高いものを使用する。このフラツクス
の投入量は、ある程度の脱Ｐを行うには溶銑トン
当たり30Kg以上を必要とするが、あまり多くなる
とその吸熱が多くなるので溶銑トン当たり80Kg程
度を限度とする。本処理においては撹拌力が極め
て大きいので溶銑中のＣによるスラグ中の酸化鉄
の還元反応が活発に起こり、スラグ中の酸化鉄濃
度の低下速度が速い。スラグ中の酸化鉄濃度が１
％以下に低下すると復Ｐが生じるので、この第二
工程中とくに酸化鉄を追添したり鉄の酸化を行わ
せたりしない場合には、この第二工程はスラグ中
の酸化鉄濃度が１％以下に低下する以前に終了す
る必要がある。
炉底からの非酸素系ガス吹込による強撹拌だけ
でこの第二工程の脱Ｐを実施する場合には、スラ
グ中の酸化鉄濃度の低下による復Ｐの問題が生じ
ない短時間の間にこの炉底からの非酸素系ガス吹
込を停止する必要性から、スラグ脱Ｐ処理時間が
短くなり、このために所望値までの脱Ｐが行えな
いこともある。このような場合には、脱Ｐ用フラ
ツクス中の酸化鉄濃度を高目にしておくのもよい
が、この酸化鉄濃度が50重量％以上となると、ス
ラグの流動性が悪くなるので、先に挙げた第二工
程の改良法としての、上吹き兼用の改良法を実施
するとよい。
この上吹き兼用の改良法は、脱Ｐ用フラツクス
を第一工程終了後の溶銑に添加した上でまたは添
加しながら炉底より非酸素系ガスを供給して該溶
銑を強撹拌しつつ酸素を上吹きした後排滓する方
法である。この方法によると、スラグに補助酸化
剤としての酸素が効果的に供給され、酸化鉄によ
る脱Ｐのための供給酸素の不足を簡便に補うこと
ができ、供給酸素の不足による復Ｐの問題を生じ
ることなく低Ｐ値まで脱Ｐが行える。
以上の第二工程並びに改良第二工程によつても
なお脱Ｐが十分ではないときは、これらをサイク
ル化するとよい。すなわち、脱Ｐ用フラツクスを
第一工程終了後の溶銑に添加した上でまたは添加
しながら炉底より非酸素系ガスを供給して該溶銑
を強撹拌するかまたはこの撹拌に加えてさらに酸
素を上吹きして脱Ｐ処理し、そのスラグを排滓す
るという段階を繰り返すのであるが、そのさい、
炭素源、Si源もしくはこれに類する酸化発熱原料
を溶銑に添加してまたは添加せずして酸素を底吹
きもしくは酸素を上底吹きするという溶銑の昇温
段階をその間に挿入するのである。第二工程並び
に改良第二工程をサイクル化する場合には溶銑温
度の低下が余儀無くされることになるが、前記の
精錬炉の特徴を利用してこの温度補償を行う操業
が簡単に実施できる。この酸素底吹きもしくは酸
素上底吹きによる昇温段階は排滓後に実施され、
酸化発熱原料としては、溶銑中のＣやSiが利用で
きるが第一工程で使用した加炭材のほか、Fe―
SiやAlなどの外部材料を用いてもよい。Ｃ以外の
酸化発熱を利用するさいには塩基度調整用に石灰
等を投入する必要がある。いずれにしても、この
酸素底吹きもしくは酸素上底吹きによる昇温段階
を挿入することによつて、第一工程終了後の含ク
ロム溶銑と同様のＣ値（4.5％以上）とSi値
（0.15％以下）を有し、溶銑温度が1500〜1700℃
となるようにし、この吹錬が終われば排滓し、第
二工程または改良第二工程を実施する。このサイ
クル化ができることに本発明の一つの特徴があ
り、クロムを含有する溶銑であつても、クロムの
酸化損失なく、所望の低Ｐ値まで含クロム溶銑の
脱Ｐが可能となる。
以上の第一工程および第二工程からなる予備脱
Ｐ処理が終了すれば、該精錬炉内で低Ｐ低Si値で
高Ｃ値の含クロム溶銑が得られる。この精錬炉は
その操業の仕方によつて含クロム溶銑の粗脱炭精
錬（酸素上底吹きまたは底吹き）、さらには、不
活性ガスもしくは不活性ガスと酸素との混合ガス
を底吹きしながらの還元・仕上げ脱炭精錬にも供
することができ、いわゆるAOD法によつて低Ｐ
ステンレス鋼を溶製できる（上底吹き転炉でも同
様である）。しかし、該精錬炉を脱Ｐ処理に主と
して利用し、これによつて低Ｐ低Si値で高Ｃ値の
（または粗脱炭として低Ｃ値の）含クロム溶銑が
得られれたならばこの溶銑をVOD法やRH・OB
法等の公知のステンレス鋼製造法で脱炭精錬でき
ることは勿論である。なお、本発明法によると、
脱Ｓも同時に行われるという付加効果も得られま
た鋼中Ｎも低下し得る。
実施例 １
表１に示す組成（表１において第一工程前の組
成）の含クロム溶銑30トンを炉底に酸素ガスと非
酸素系ガスとを吹込可能な羽口を有し酸素上吹き
ランスを備えたAOD炉に装入した後、コークス
粒1.2トン、石灰１トンを投入し、炉底羽口から
アルゴンガスと酸素ガスとを合計2000Nm3／hr吹
き込み酸素ガスを600Nm3／hr上吹きして第一工
程を終了した。そのときの溶銑組成は表１に示す
第一工程（後）のものであつた。
ついで、第二工程として、炭酸リチウム150
Kg、石灰300Kg、ホタル石900Kg、ミルスケール
750Kg、を投入し、炉底羽口からアルゴンガスを
700Nm3／hr吹き込んで第二工程を終了した。得
られた溶銑組成を表１の第二工程（後）の欄に示
した。
この第二工程終了後、引き続いてこの精錬炉で
通常のAOD法に従う精錬法により、脱炭精錬、
還元精錬、および成分調整をおこなつて表１の第
三工程（後）の欄に示す組成の低Ｐステンレス鋼
が得られた。
The present invention can advantageously dephosphorize chromium-containing hot metal, which contains a relatively large amount of P, as a starting material for manufacturing (melting) chromium-containing steel, especially stainless steel. The present invention relates to a method of manufacturing low P stainless steel. P (phosphorus) in steel often acts harmfully except in special cases, and in particular, in the case of stainless steel, it often shows effects that promote hot cracking and stress corrosion cracking. Are known. but
Removing P from Cr-containing hot metal is more difficult than from ordinary steel, and in actual operations, raw materials with low P content are carefully selected to produce low-P chromium-containing hot metal, which is then subjected to decarburization refining. was normal. The present invention was made for the purpose of developing a new chromium-containing steel refining method that can use P-containing raw materials that cannot be used in conventional methods as raw materials for producing chromium-containing steel. To this end, we
How to use the deP flux for chromium-containing hot metal, which has already been proposed in Japanese Patent Application Laid-open No. 56-5910 filed by the same applicant, to advantageously convert chromium-containing hot metal to low-P molten steel. As a result of conducting various tests and research on the scale of interfering equipment to determine whether refining is possible, we were able to establish a new refining method for producing low-P chromium steel from high-P chromium-containing hot metal. The refining method for producing low-P chromium steel from high-P chromium-containing hot metal according to the present invention involves refining chromium-containing steel using chromium-containing hot metal containing 3% by weight or more of Cr as a starting material, before decarburizing the chromium-containing steel. In,
Putting the chromium-containing hot metal into a smelting furnace that has a double-tube tuyere that can simultaneously or selectively inject oxygen-based gas and non-oxygen-based gas into the furnace bottom and that is capable of top-blowing oxygen,
The C content after the blowing of the first step is 4.5% by weight.
After or while adding a sufficient amount of carbon source to the chromium-containing hot metal in the refining furnace, a non-oxygen gas is supplied from the bottom of the furnace to agitate the hot metal, and Si is 0.15% by weight or less. The first step is to carry out oxygen bottom blowing or oxygen top and bottom blowing until A second step of strongly stirring the hot metal by supplying more non-oxygen gas to forcibly bring the slag and hot metal into contact and then discharging the slag is carried out in advance. The method is characterized in that low P-containing hot metal is decarburized and refined to a desired carbon value using this refining furnace or a combination of this refining furnace and another refining furnace. In addition, in the second step of the preliminary deP treatment in this refining method, a non-oxygen gas is supplied from the furnace bottom after or while adding the deP flux to the hot metal after the first step. A step of vigorously stirring the slag and forcing the molten pig iron into contact with the slag and then removing the slag, a carbon source,
a heating stage of the hot metal consisting of bottom blowing oxygen or top blowing oxygen with or without addition of a Si source or similar oxidative exothermic raw material to the hot metal; and deP to a target P content. It can be replaced by a cycle process that is repeated until the first process is completed, and non-oxygen gas can be supplied from the bottom of the furnace after or while adding the deP flux to the hot metal after the first process. It may be replaced with an improved second step in which the hot metal is strongly stirred and oxygen is blown over the top and then slag is removed.Alternatively, the deP flux may be added to the hot metal after the first step or while it is being added. A step of supplying a non-oxygen gas from the bottom of the furnace and vigorously stirring the hot metal while blowing oxygen upwards and then exhausting the slag, and adding or adding a carbon source, a Si source, or a similar oxidizing exothermic raw material to the hot metal. a heating stage of the hot metal consisting of bottom blowing oxygen or top blowing oxygen;
It can also be replaced by an improved cycle step consisting of repeating the process until the target P content is dephosphorized. As the dephosphorizing flux to be applied to the refining method of the present invention, it is advantageous to use the one described in Japanese Patent Application Laid-Open No. 56-5910. That is, in carrying out the method of the present invention, one or two of alkaline earth metal fluorides and chlorides are used as the dephosphorizing flux.
30 to 80% by weight of lithium oxides and carbonates, and 0.4 to 30% by weight of one or more of lithium oxides and carbonates.
and one or two of iron oxide and nickel oxide
5 to 50% by weight of species or more, and 0 to 40% of one or more of alkaline earth metal oxides and carbonates.
Fluxes consisting of less than % can be used. The present invention is carried out using a refining furnace that has a double pipe tuyere at the bottom of the furnace that can simultaneously or selectively inject oxygen-based gas and non-oxygen-based gas, and is equipped with an oxygen top blowing lance. As such a refining furnace, a top-bottom blowing furnace having a concentric double tube tuyere at the bottom (including the lower part of the furnace side) and an oxygen top-blowing lance is preferable for actual operation. In this case, a blowing operation is usually performed in which pure oxygen or a mixture of oxygen and non-oxygen gas is blown into the inner pipe of the double-tube tuyeres at the bottom of the furnace, and cooling gas is blown into the outer pipe. It is also possible to use a method in which non-oxygen gases such as argon gas, nitrogen gas, hydrocarbon gas, carbon dioxide gas, water vapor, etc., singly or in combination, can be blown into the tuyere for stirring the hot water without blowing into the tuyere. Keep it.
By using such a refining furnace, both the preliminary deP treatment before the decarburization refining according to the present invention and the decarburization refining can be effectively carried out. In other words, it is possible to carry out carburization of chromium-containing hot metal and blowing that effectively performs the Si-removal reaction, and the resulting high C value and low
The slag dephosphorization treatment for hot metal with a high Si value can be efficiently realized, and the subsequent decarburization refining can be carried out without difficulty according to a conventional method. The first step of preliminary deP treatment using this smelting furnace is
This is a process in which chromium-containing hot metal procured by using a P-containing raw material is carburized and deSi-removed, and at the same time, the hot water temperature is maintained or raised to the level required for de-P in the next step. In order to effectively dephosphorize slag from chromium-containing hot metal using a dephosphorizing flux, it is necessary to increase the chances of contact with this slag. That is, the C content in the hot metal is at least 4.5% by weight) and the Si content is 0.2% or less, preferably 0.15% by weight.
It is preferable to carry out the following chromium-containing hot metal with high C and low Si, and it is also necessary to maintain the hot metal temperature at a predetermined level or higher. The first step of the present invention is a step of realizing this in the above-mentioned refining furnace. main
When high carbon ferrochrome is used as a Cr source, the C value of the resulting chromium-containing hot metal usually does not reach the above level, and the Si content is higher than the above level unless special treatment is performed. In the first step, such low C, high Si, chromium-containing hot metal is put into the refining furnace, and a sufficient amount of carbon source ( For example, coke powder or coke grains) are added to the chromium-containing hot metal in the smelting furnace, and then a non-oxygen gas (for example, argon gas or nitrogen gas) is supplied from the bottom of the furnace to stir the hot metal. but
Oxygen bottom blowing or oxygen top and bottom blowing is carried out until it becomes 0.15% by weight or less. The carbon source may be added from the top of the furnace, but it can also be introduced along with the non-oxygen gas blown from the bottom of the furnace. Carburization of hot metal is an endothermic reaction, but oxygen bottom blowing or oxygen top and bottom blowing causes a Si removal reaction and heat rises. Since this deSi reaction starts at low temperatures with priority over the decarburization reaction, in this first step, oxygen bottom blowing or oxygen top blowing under stirring is used to perform carburization, deSi removal, The three requirements for slag dephosphorization and temperature increase can be achieved simultaneously. Note that the carburization reaction progresses better as the stirring intensity by the bottom-blown gas increases. If the initial Si concentration is high and the amount of Si removed is large, it is necessary to add lime or the like to adjust the basicity of the slag. The first step is completed by discharging the generated slag, but if the calorific value is insufficient, temperature compensation may be performed by an oxidation reaction of C or the like. In the second step, after or while adding the above-mentioned deP flux to the hot metal after the first step, non-oxygen gas is supplied from the bottom of the furnace to strongly stir the hot metal, and the slag and hot metal are separated. After forced contact with the material, the slag is discharged. This deP flux may be added from the top of the furnace, or may be introduced along with the gas blown from the bottom of the furnace. At that time, it may be added all at once, but it is more effective to add it in batches or continuously. Further, the stronger the stirring intensity by the non-oxygen gas blown in from the bottom of the furnace, the better the dephosphorization progresses, and the flow rate is preferably 10 Nm 3 /hr·t or more. In actual operation, fluorite, industrial lithium carbonate, mill scale, lime, etc. are easily used as the above-mentioned flux for removing P. These flux raw materials should be as pure as possible so as not to contaminate the produced slag. The amount of flux input is required to be 30 kg or more per ton of hot metal in order to perform a certain degree of dephosphorization, but if it is too large, the heat absorption will increase, so the input amount is limited to about 80 kg per ton of hot metal. In this process, since the stirring power is extremely large, the reduction reaction of iron oxide in the slag by carbon in the hot metal occurs actively, and the iron oxide concentration in the slag decreases rapidly. Iron oxide concentration in slag is 1
If the iron oxide concentration in the slag falls below 1%, reproducibility will occur, so if iron oxide is not added or iron is oxidized during this second step, the iron oxide concentration in the slag is 1%. Must be finished before it drops below. If this second step of deP is carried out only by strong stirring by blowing non-oxygen gas from the bottom of the furnace, this process can be carried out in a short period of time without causing the problem of re-P due to a decrease in the concentration of iron oxide in the slag. Since it is necessary to stop the injection of non-oxygen gas from the bottom of the furnace, the time required for the slag dephosphorization process becomes short, and therefore dephosphorization may not be achieved to a desired level. In such cases, it is a good idea to increase the iron oxide concentration in the deP flux, but if the iron oxide concentration exceeds 50% by weight, the fluidity of the slag will deteriorate, so As an improvement method for the second step mentioned above, it is preferable to implement an improvement method that combines top blowing. This improved top-blowing method involves adding non-oxygen gas from the bottom of the furnace after or while adding flux for dephosphorization to the hot metal after the first step, and vigorously stirring the hot metal while removing oxygen. This method involves top-blowing and then discharging the slag. According to this method, oxygen as an auxiliary oxidant is effectively supplied to the slag, and the lack of supplied oxygen for dephosphorization by iron oxide can be easily compensated for, and the problem of repurification due to lack of supplied oxygen can be solved. It is possible to remove P to a low P value without any occurrence. If P removal is still not sufficient even after the above second step and improved second step, it is preferable to cycle these steps. That is, after or while adding the deP flux to the hot metal after the first step, a non-oxygen gas is supplied from the bottom of the furnace and the hot metal is strongly stirred, or in addition to this stirring, oxygen is further added. The steps of top-blowing, dephosphorous treatment, and slag removal are repeated, but at that time,
In between, a heating stage of the hot metal is inserted in which oxygen is bottom blown or oxygen is blown from the top, with or without adding a carbon source, a Si source, or a similar oxidizing exothermic raw material to the hot metal. When cycling the second step and the improved second step, the temperature of the hot metal must be lowered, but operations that compensate for this temperature can be easily carried out by utilizing the characteristics of the smelting furnace described above. This temperature raising stage by oxygen bottom blowing or oxygen top and bottom blowing is carried out after the slag is discharged.
C and Si in hot metal can be used as oxidative exothermic raw materials, but in addition to the carburizer used in the first step, Fe-
External materials such as Si and Al may also be used. When using heat generated by oxidation other than C, it is necessary to add lime or the like to adjust the basicity. In any case, by inserting the temperature raising stage by oxygen bottom blowing or oxygen top and bottom blowing, the C value (4.5% or more) and Si value (0.15 % or less), and the hot metal temperature is 1500~1700℃
After this blowing is completed, the slag is discharged and the second step or improved second step is carried out. One of the features of the present invention is that this cycling is possible, and even if the hot metal contains chromium, it is possible to deP the chromium-containing hot metal to a desired low P value without oxidation loss of chromium. When the preliminary deP treatment consisting of the first and second steps described above is completed, chromium-containing hot metal with a low P and low Si value and a high C value is obtained in the refining furnace. Depending on the method of operation, this smelting furnace can perform crude decarburization of chromium-containing hot metal (oxygen top and bottom blowing or bottom blowing), or bottom blowing of inert gas or a mixed gas of inert gas and oxygen. It can also be used for reduction/finish decarburization refining, and low P
Stainless steel can be melted (the same is true for top-bottom blowing converters). However, if the smelting furnace is mainly used for deP treatment, and thereby chromium-containing hot metal with a low P, low Si value, and high C value (or a low C value as crude decarburization) is obtained, this hot metal VOD method or RH/OB
It goes without saying that the decarburization process can be carried out using a known stainless steel manufacturing method such as the method. According to the method of the present invention,
An additional effect is obtained in that S removal is carried out at the same time, and N in the steel can also be reduced. Example 1 30 tons of chromium-containing hot metal having the composition shown in Table 1 (composition before the first step in Table 1) was transferred to an oxygen top-blowing lance having a tuyere capable of injecting oxygen gas and non-oxygen gas into the furnace bottom. After charging into an AOD furnace with The first step was completed. The hot metal composition at that time was that of the first step (after) shown in Table 1. Then, as a second step, lithium carbonate 150
Kg, lime 300Kg, fluorite 900Kg, mill scale
750Kg was input, and argon gas was introduced from the bottom tuyere.
The second step was completed by blowing 700Nm 3 /hr. The composition of the obtained hot metal is shown in the second step (after) column of Table 1. After completing this second step, decarburization and refining are performed in this smelting furnace using a refining method that follows the normal AOD method.
After reduction refining and component adjustment, a low P stainless steel having the composition shown in the third step (after) column of Table 1 was obtained.
【表】
実施例 ２
表２に示す組成（表２において第一工程前の組
成）の含クロム溶銑30トンを炉底に酸素ガスと非
酸素系ガスとを吹込可能な羽口を有し酸素上吹き
ランスを備えたAOD炉に装入した後、コークス
粒1.2トン、石灰１トンを投入し、炉底羽口から
アルゴンガスと酸素ガスとを合計2000Nm3／hr吹
き込んで第一工程を終了した。そのときの溶銑組
成は表２に示す第一工程（後）のものであつた。
ついで、第二工程として、炭酸リチウム150
Kg、石灰300Kg、ホタル石900Kg、ミルスケール
500Kg、を投入し、炉底羽口からアルゴンガス
700Nm3／hr吹き込みながら上吹きランスから酸
素ガスを600Nm3／hr吹き込んで第二工程を終了
した。得られた溶銑組成を表２の第二工程（後）
の欄に示した。
この第二工程終了後、引き続いてこの精錬炉で
通常のAOD法に従う精錬法により、脱炭精錬、
還元精錬、および成分調整をおこなつて表２の第
三工程（後）の欄に示す組成の低Ｐステンレス鋼
が得られた。[Table] Example 2 30 tons of chromium-containing hot metal with the composition shown in Table 2 (composition before the first step in Table 2) was heated to the bottom of the furnace, which had a tuyere capable of injecting oxygen gas and non-oxygen gas. After charging into an AOD furnace equipped with a top blowing lance, 1.2 tons of coke grains and 1 ton of lime were added, and a total of 2000Nm 3 /hr of argon gas and oxygen gas was blown into the furnace bottom tuyeres to complete the first process. did. The hot metal composition at that time was that of the first step (after) shown in Table 2. Then, as a second step, lithium carbonate 150
Kg, lime 300Kg, fluorite 900Kg, mill scale
500Kg was input, and argon gas was released from the bottom tuyere.
The second step was completed by blowing oxygen gas at 600Nm 3 /hr from the top blowing lance while blowing 700Nm 3 /hr. The obtained hot metal composition is shown in Table 2 in the second step (after).
It is shown in the column. After completing this second step, decarburization and refining are carried out in this smelting furnace using a smelting method that follows the normal AOD method.
After reduction refining and component adjustment, a low P stainless steel having the composition shown in the third step (after) column of Table 2 was obtained.
【表】
実施例 ３
実施例２の第二工程を二回繰り返した以外は実
施例２と同様の操業を行つた。
そのさい、この第一回目の第二工程と第二回目
の第二工程との間において、石灰1.0トン、フエ
ロシリコン0.3トン、コークス粒0.5トンを投入
し、炉底の羽口から、アルゴンガスと酸素ガスを
合計で2000Nm3／hrを底吹きしながら上吹きラン
スから酸素ガスを600Nm3／hr吹精し、溶銑温度
を1570℃にまで上昇させた。
表３にその操業結果を示した。
なお、表３に第四工程として示したのは、この
第一回目の第二工程と第二回目の第二工程との間
に実施した昇温段階を示しており、表３中の第一
工程、第二工程および第三工程は、実施例２の場
合と実質上変わりはない。[Table] Example 3 The same operation as in Example 2 was carried out except that the second step of Example 2 was repeated twice. At that time, between the second step of the first time and the second step of the second time, 1.0 tons of lime, 0.3 tons of ferrosilicon, and 0.5 tons of coke grains were added, and argon was While blowing gas and oxygen gas at a total of 2000 Nm 3 /hr from the bottom, oxygen gas was blown at 600 Nm 3 /hr from the top blowing lance, and the temperature of the hot metal was raised to 1570°C. Table 3 shows the operational results. In addition, what is shown as the fourth step in Table 3 indicates the temperature raising step carried out between the second step of the first time and the second step of the second time. The steps, second step and third step are substantially the same as in Example 2.
【表】【table】
【表】【table】
Claims (1)
出発材料に用いて含クロム鋼を精錬するにあた
り、その脱炭精錬前において、炉底に酸素系ガス
および非酸素系ガスを同時に若しくは選択的に吹
込可能な二重管羽口を有しかつ酸素上吹可能な精
錬炉に該含クロム溶銑を入れ、以下の工程、即
ち、 第一工程の吹錬終了後のＣ含有量が4.5重量％
以上となるに十分な量の炭素源をこの精錬炉内含
クロム溶銑に添加した上でまたは添加しながら炉
底より非酸素系ガスを供給して該溶銑を撹拌しつ
つSiが0.15重量％以下になるまで酸素底吹き吹錬
もしくは酸素上底吹き吹錬を実施しついで排滓す
る第一工程と、 脱Ｐ用フラツクスを第一工程終了後の溶銑に添
加した上でまたは添加しながら炉底より非酸素系
ガスを供給して該溶銑を強撹拌し、スラグと溶銑
を強制的に接触させた後排滓する第二工程と、 からなる予備脱Ｐ処理を予め実施し、 次いで、得られた低Ｐ含クロム溶銑をこの精錬
炉またはこの精錬炉とほかの精錬炉との組合せで
所望の炭素値まで脱炭精錬することからなる低Ｐ
含クロム鋼の製造法。 ２ 脱Ｐ用フラツクスは、アルカリ土類金属のフ
ツ化物、塩化物のうち１種または２種以上が30〜
80重量％と、リチウムの酸化物、炭酸塩のうち１
種または２種以上が0.4〜30重量％と、鉄酸化
物、酸化ニツケルのうち１種または２種以上が５
〜50重量％と、アルカリ土類金属の酸化物、炭酸
塩のうち１種または２種以上が０〜40％未満と、
からなる特許請求の範囲第１項記載の低Ｐ含クロ
ム鋼の製造法。 ３ Crを３重量％以上含有する含クロム溶銑を
出発材料に用いて含クロム鋼を精錬するにあた
り、その脱炭精錬前において、炉底に酸素系ガス
および非酸素系ガスを同時に若しくは選択的に吹
込可能な二重管羽口を有しかつ酸素上吹可能な精
錬炉に該含クロム溶銑を入れ、以下の工程、即
ち、 第一工程の吹錬終了後のＣ含有量が4.5重量％
以上となるに十分な量の炭素源をこの精錬炉内含
クロム溶銑に添加した上でまたは添加しながら炉
底より非酸素系ガスを供給して該溶銑を撹拌しつ
つSiが0.15重量％以下になるまで酸素底吹き吹錬
もしくは酸素上底吹き吹錬を実施しついで排滓す
る第一工程と、 脱Ｐ用フラツクスを第一工程終了後の溶銑に添
加した上でまたは添加しながら炉底より非酸素系
ガスを供給して該溶銑を強撹拌し、スラグと溶銑
を強制的に接触させた後排滓する段階と、炭素
源、Si源、もしくはこれに類する酸化発熱原料を
溶銑に添加してまたは添加せずして酸素を底吹き
もしくは上底吹きすることからなる溶銑の昇温段
階と、を目標Ｐ含有量に脱Ｐされるまで繰り返す
ことからなる第二工程と、 からなる予備脱Ｐ処理を予め実施し、 次いで、得られた低Ｐ含クロム溶銑をこの精錬
炉またはこの精錬炉とほかの精錬炉との組合せで
所望の炭素値まで脱炭精錬することからなる低Ｐ
含クロム鋼の製造法。 ４ 脱Ｐ用フラツクスは、アルカリ土類金属のフ
ツ化物、塩化物のうち１種または２種以上が30〜
80重量％と、リチウムの酸化物、炭酸塩のうち１
種または２種以上が0.4〜30重量％と、鉄酸化
物、酸化ニツケルのうち１種または２種以上が５
〜50重量％と、アルカリ土類金属の酸化物、炭酸
塩のうち１種または２種以上が０〜40％未満と、
からなる特許請求の範囲第３項記載の低Ｐ含クロ
ム鋼の製造法。 ５ Crを３重量％以上含有する含クロム溶銑を
出発材料を用いて含クロム鋼を精錬するにあた
り、その脱炭精錬前において、炉底に酸素系ガス
および非酸素系ガスを同時に若しくは選択的に吹
込可能な二重管羽口を有しかつ酸素上吹可能な精
錬炉に該含クロム溶銑を入れ、以下の工程、即
ち、 第一工程の吹錬終了後のＣ含有量が4.5重量％
以上となるに十分な量の炭素源をこの精錬炉内含
クロム溶銑に添加した上でまたは添加しながら炉
底より非酸素系ガスを供給して該溶銑を撹拌しつ
つSiが0.15重量％以下になるまで酸素底吹き吹錬
もしくは酸素上底吹き吹錬を実施しついで排滓す
る第一工程と、 脱Ｐ用フラツクスを第一工程終了後の溶銑に添
加した上でまたは添加しながら炉底より非酸素系
ガスを供給して該溶銑を強撹拌しつつ酸素を上吹
きした後排滓する第二工程と、 からなる予備脱Ｐ処理を予め実施し、 次いで、得られた低Ｐ含クロム溶銑をこの精錬
炉またはこの精錬炉とほかの精錬炉との組合せで
所望の炭素値まで脱炭精錬することからなる低Ｐ
含クロム鋼の製造法。 ６ 脱Ｐ用フラツクスは、アルカリ土類金属のフ
ツ化物、塩化物のうち１種または２種以上が30〜
80重量％と、リチウムの酸化物、炭酸塩のうち１
種または２種以上が0.4〜30重量％と、鉄酸化
物、酸化ニツケルのうち１種または２種以上が５
〜50重量％と、アルカリ土類金属の酸化物、炭酸
塩のうち１種または２種以上が０〜40％未満と、
からなる特許請求の範囲第５項記載の低Ｐ含クロ
ム鋼の製造法。 ７ Crを３重量％以上含有する含クロム溶銑を
出発材料を用いて含クロム鋼を精錬するにあた
り、その脱炭精錬前において、炉底に酸素系ガス
および非酸素系ガスを同時に若しくは選択的に吹
込可能な二重管羽口を有しかつ酸素上吹可能な精
錬炉に該含クロム溶銑を入れ、以下の工程、即
ち、 第一工程の吹錬終了後のＣ含有量が4.5重量％
以上となるに十分な量の炭素源をこの精錬炉内含
クロム溶銑に添加した上でまたは添加しながら炉
底より非酸素系ガスを供給して該溶銑を撹拌しつ
つSiが0.15重量％以下になるまで酸素底吹き吹錬
もしくは酸素上底吹き吹錬を実施しついで排滓す
る第一工程と、 脱Ｐ用フラツクスを第一工程終了後の溶銑に添
加した上でまたは添加しながら炉底より非酸素系
ガスを供給して該溶銑を強撹拌しつつ酸素を上吹
きした後排滓する段階と、炭素源、Si源もしくは
これに類する酸化発熱原料を溶銑に添加してまた
は添加せずして酸素を底吹きもしくは上底吹きす
ることからなる溶銑の昇温段階と、を目標Ｐ含有
量に脱Ｐされるまで繰り返すことからなる第二工
程と、 からなる予備脱Ｐ処理を予め実施し、 次いで、得られた低Ｐ含クロム溶銑をこの精錬
炉またはこの精錬炉とほかの精錬炉との組合せで
所望の炭素値まで脱炭精錬することからなる低Ｐ
含クロム鋼の製造法。 ８ 脱Ｐ用フラツクスは、アルカリ土類金属のフ
ツ化物、塩化物のうち１種または２種以上が30〜
80重量％と、リチウムの酸化物、炭酸塩のうち１
種または２種以上が0.4〜30重量％と、鉄酸化
物、酸化ニツケルのうち１種または２種以上が５
〜50重量％と、アルカリ土類金属の酸化物、炭酸
塩のうち１種または２種以上が０〜40％未満と、
からなる特許請求の範囲第７項記載の低Ｐ含クロ
ム鋼の製造法。[Claims] 1. When refining chromium-containing steel using chromium-containing hot metal containing 3% by weight or more of Cr as a starting material, oxygen-based gas and non-oxygen-based gas are added to the bottom of the furnace before decarburization refining. The chromium-containing hot metal is put into a smelting furnace that has a double tube tuyere that can simultaneously or selectively inject oxygen and that can top blow oxygen, and performs the following steps: The amount is 4.5% by weight
After or while adding a sufficient amount of carbon source to the chromium-containing hot metal in the refining furnace, a non-oxygen gas is supplied from the bottom of the furnace to agitate the hot metal, and Si is 0.15% by weight or less. The first step is to carry out oxygen bottom blowing or oxygen top and bottom blowing until A second step of strongly stirring the hot metal by supplying more non-oxygen gas to forcibly bring the slag and hot metal into contact and then discharging the slag is carried out in advance. Low P chromium-containing hot metal is decarburized and refined to a desired carbon value using this smelting furnace or a combination of this smelting furnace and other smelting furnaces.
Manufacturing method of chromium-containing steel. 2 The flux for dephosphorization contains one or more of alkaline earth metal fluorides and chlorides with a content of 30 to 30%.
80% by weight and 1 of lithium oxides and carbonates
0.4 to 30% by weight of one or more species, and 5% of one or more of iron oxide and nickel oxide.
~50% by weight, and 0 to less than 40% of one or more of alkaline earth metal oxides and carbonates,
A method for producing a low P chromium-containing steel according to claim 1. 3 When refining chromium-containing steel using chromium-containing hot metal containing 3% by weight or more of Cr as a starting material, oxygen-based gas and non-oxygen-based gas are simultaneously or selectively added to the furnace bottom before decarburization refining. The chromium-containing hot metal is put into a smelting furnace that has a double pipe tuyere that can be blown and is capable of top blowing with oxygen, and the following steps are carried out, namely: After the completion of the first blowing step, the C content is 4.5% by weight.
After or while adding a sufficient amount of carbon source to the chromium-containing hot metal in the refining furnace, a non-oxygen gas is supplied from the bottom of the furnace to agitate the hot metal, and Si is 0.15% by weight or less. The first step is to carry out oxygen bottom blowing or oxygen top and bottom blowing until A step of strongly stirring the hot metal by supplying a non-oxygen gas, forcing the slag and the hot metal into contact, and then discharging the slag, and adding a carbon source, Si source, or similar oxidizing exothermic raw material to the hot metal. a heating step of the hot metal consisting of bottom-blowing or top-blowing with or without addition of oxygen; a second step consisting of repeating the steps until the target P content is dephosphorized A low P process is carried out in advance, and then the obtained low P chromium-containing hot metal is decarburized and refined to a desired carbon value in this smelting furnace or a combination of this smelting furnace and another smelting furnace.
Manufacturing method of chromium-containing steel. 4 The flux for dephosphorization contains one or more of alkaline earth metal fluorides and chlorides of 30 to 30%.
80% by weight and 1 of lithium oxides and carbonates
0.4 to 30% by weight of one or more species, and 5% of one or more of iron oxide and nickel oxide.
~50% by weight, and 0 to less than 40% of one or more of alkaline earth metal oxides and carbonates,
A method for producing a low P chromium-containing steel according to claim 3. 5 When refining chromium-containing steel using chromium-containing hot metal containing 3% by weight or more of Cr as a starting material, oxygen-based gas and non-oxygen-based gas are simultaneously or selectively added to the furnace bottom before decarburization refining. The chromium-containing hot metal is put into a smelting furnace that has a double pipe tuyere that can be blown and is capable of top blowing with oxygen, and the following steps are carried out, namely: After the completion of the first blowing step, the C content is 4.5% by weight.
After or while adding a sufficient amount of carbon source to the chromium-containing hot metal in the refining furnace, a non-oxygen gas is supplied from the bottom of the furnace to agitate the hot metal, and Si is 0.15% by weight or less. The first step is to carry out oxygen bottom blowing or oxygen top and bottom blowing until A preliminary deP treatment consisting of a second step of supplying a non-oxygen gas, vigorously stirring the hot metal, blowing oxygen over it, and then discharging the slag is carried out in advance, and then the obtained low P chromium-containing Low P, which consists of decarburizing and refining hot metal to a desired carbon value in this smelting furnace or in combination with this smelting furnace and other smelting furnaces.
Manufacturing method of chromium-containing steel. 6. The flux for dephosphorization contains one or more of alkaline earth metal fluorides and chlorides of 30 to 30%.
80% by weight and 1 of lithium oxides and carbonates
0.4 to 30% by weight of one or more species, and 5% of one or more of iron oxide and nickel oxide.
~50% by weight, and 0 to less than 40% of one or more of alkaline earth metal oxides and carbonates,
A method for producing a low P chromium-containing steel according to claim 5. 7 When refining chromium-containing steel using chromium-containing hot metal containing 3% by weight or more of Cr as a starting material, oxygen-based gas and non-oxygen-based gas are simultaneously or selectively added to the furnace bottom before decarburization refining. The chromium-containing hot metal is put into a smelting furnace that has a double pipe tuyere that can be blown and is capable of top blowing with oxygen, and the following steps are carried out, namely: After the completion of the first blowing step, the C content is 4.5% by weight.
After or while adding a sufficient amount of carbon source to the chromium-containing hot metal in the refining furnace, a non-oxygen gas is supplied from the bottom of the furnace to agitate the hot metal, and Si is 0.15% by weight or less. The first step is to carry out oxygen bottom blowing or oxygen top and bottom blowing until a step of supplying a non-oxygen gas to the hot metal, blowing oxygen over the hot metal while vigorously stirring the hot metal, and then discharging the hot metal; and a step of adding or not adding a carbon source, a Si source, or a similar oxidizing exothermic raw material to the hot metal. A preliminary deP treatment is carried out in advance, consisting of: a step of raising the temperature of the hot metal, which consists of bottom-blowing or top-bottom blowing of oxygen; Then, the resulting low-P chromium-containing hot metal is decarburized and refined to a desired carbon value in this smelting furnace or in a combination of this smelting furnace and another smelting furnace.
Manufacturing method of chromium-containing steel. 8 The flux for dephosphorization contains one or more of alkaline earth metal fluorides and chlorides of 30 to 30%.
80% by weight and 1 of lithium oxides and carbonates
0.4 to 30% by weight of one or more species, and 5% of one or more of iron oxide and nickel oxide.
~50% by weight, and 0 to less than 40% of one or more of alkaline earth metal oxides and carbonates,
A method for producing a low P chromium-containing steel according to claim 7.
Priority Applications (8)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58087296A JPS59211519A (en) | 1983-05-18 | 1983-05-18 | Production of low p-containing chromium steel |
| KR1019840002639A KR910009961B1 (en) | 1983-05-18 | 1984-05-16 | Process for producing low p chromium-containing steel |
| SE8402668A SE459184B (en) | 1983-05-18 | 1984-05-17 | PROCEDURES FOR PREPARING CHROME STAINLESS STEEL WITH LOW PHOSPHORUS CONTENT |
| IT67492/84A IT1179669B (en) | 1983-05-18 | 1984-05-17 | PROCEDURE FOR PRODUCING A LOW CHROME STEEL P |
| FR848407683A FR2546182B1 (en) | 1983-05-18 | 1984-05-17 | PROCESS FOR PRODUCING STEEL CONTAINING LOW P CONTENT CHROMIUM |
| ES532584A ES8603583A1 (en) | 1983-05-18 | 1984-05-17 | Process for producing low P chromium-containing steel |
| DE3418643A DE3418643C2 (en) | 1983-05-18 | 1984-05-18 | Process for producing chromium containing low phosphorus |
| GB08412791A GB2141739B (en) | 1983-05-18 | 1984-05-18 | Process for producing low p chromium-containing steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58087296A JPS59211519A (en) | 1983-05-18 | 1983-05-18 | Production of low p-containing chromium steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS59211519A JPS59211519A (en) | 1984-11-30 |
| JPS6213405B2 true JPS6213405B2 (en) | 1987-03-26 |
Family
ID=13910852
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP58087296A Granted JPS59211519A (en) | 1983-05-18 | 1983-05-18 | Production of low p-containing chromium steel |
Country Status (8)
| Country | Link |
|---|---|
| JP (1) | JPS59211519A (en) |
| KR (1) | KR910009961B1 (en) |
| DE (1) | DE3418643C2 (en) |
| ES (1) | ES8603583A1 (en) |
| FR (1) | FR2546182B1 (en) |
| GB (1) | GB2141739B (en) |
| IT (1) | IT1179669B (en) |
| SE (1) | SE459184B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03119308U (en) * | 1990-03-14 | 1991-12-09 |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63216917A (en) * | 1987-03-05 | 1988-09-09 | Nippon Steel Corp | Method for refining molten steel in molten metal vessel |
| DE102005032929A1 (en) * | 2004-11-12 | 2006-05-18 | Sms Demag Ag | Production of stainless steel of the ferritic steel group AISI 4xx in an AOD converter |
| DE102006056671A1 (en) * | 2006-11-30 | 2008-06-05 | Sms Demag Ag | Method and apparatus for stainless steel production without electrical energy supply on the basis of pig iron pretreated in a DDD plant |
| DE102006056672A1 (en) | 2006-11-30 | 2008-06-05 | Sms Demag Ag | Method and apparatus for stainless steel production without electrical energy supply based on pig iron |
| DE102007015585A1 (en) * | 2007-03-29 | 2008-10-02 | M.K.N. Technologies Gmbh | Melt metallurgical process for producing molten metals and transition metal-containing aggregate for use therein |
| CN114875211B (en) * | 2022-05-18 | 2023-10-31 | 山西太钢不锈钢股份有限公司 | Method for smelting stainless steel and efficiently desilicating |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS531620A (en) * | 1976-06-28 | 1978-01-09 | Nippon Steel Corp | Production of high chromium steel |
| JPS532324A (en) * | 1976-06-29 | 1978-01-11 | Nippon Steel Corp | Melting and ingot casting of low phosphor chromium steel |
| JPS565910A (en) * | 1979-06-29 | 1981-01-22 | Nisshin Steel Co Ltd | Dephosphorizing method of pig iron containing chromium |
| JPS5852412A (en) * | 1981-09-22 | 1983-03-28 | Nippon Steel Corp | Dephosphorizing method for molten iron |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| LU80006A1 (en) * | 1978-07-20 | 1980-02-14 | Arbed | PROCESS FOR THE PREPARATION OF CHROMED ALLOY STEELS, ESPECIALLY STAINLESS STEELS |
| US4295882A (en) * | 1978-10-24 | 1981-10-20 | Nippon Steel Corporation | Steel making process |
| GB2049731B (en) * | 1979-05-19 | 1983-03-30 | Tokushu Kinzoku Kenkyujo Kk | Refining process for removing acid oxide-forming elements from high-ni and/or high-co alloy steel |
| JPS6023182B2 (en) * | 1979-12-01 | 1985-06-06 | 新日本製鐵株式会社 | Melting method for medium carbon high chromium molten metal |
| GB2078260B (en) * | 1980-06-20 | 1984-08-08 | Nisshin Steel Co Ltd | Refining cr-containing iron |
| JPS5770219A (en) * | 1980-10-21 | 1982-04-30 | Nisshin Steel Co Ltd | Method for dephosphorizing, desulfurizing and denitrifying iron alloy |
| IT1171888B (en) * | 1982-12-02 | 1987-06-10 | Nippon Steel Corp | PROCEDURE FOR THE PRODUCTION OF STAINLESS STEEL |
-
1983
- 1983-05-18 JP JP58087296A patent/JPS59211519A/en active Granted
-
1984
- 1984-05-16 KR KR1019840002639A patent/KR910009961B1/en not_active IP Right Cessation
- 1984-05-17 SE SE8402668A patent/SE459184B/en not_active IP Right Cessation
- 1984-05-17 IT IT67492/84A patent/IT1179669B/en active
- 1984-05-17 ES ES532584A patent/ES8603583A1/en not_active Expired
- 1984-05-17 FR FR848407683A patent/FR2546182B1/en not_active Expired
- 1984-05-18 GB GB08412791A patent/GB2141739B/en not_active Expired
- 1984-05-18 DE DE3418643A patent/DE3418643C2/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS531620A (en) * | 1976-06-28 | 1978-01-09 | Nippon Steel Corp | Production of high chromium steel |
| JPS532324A (en) * | 1976-06-29 | 1978-01-11 | Nippon Steel Corp | Melting and ingot casting of low phosphor chromium steel |
| JPS565910A (en) * | 1979-06-29 | 1981-01-22 | Nisshin Steel Co Ltd | Dephosphorizing method of pig iron containing chromium |
| JPS5852412A (en) * | 1981-09-22 | 1983-03-28 | Nippon Steel Corp | Dephosphorizing method for molten iron |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03119308U (en) * | 1990-03-14 | 1991-12-09 |
Also Published As
| Publication number | Publication date |
|---|---|
| IT8467492A1 (en) | 1985-11-17 |
| SE459184B (en) | 1989-06-12 |
| KR840008921A (en) | 1984-12-20 |
| KR910009961B1 (en) | 1991-12-07 |
| GB2141739A (en) | 1985-01-03 |
| ES532584A0 (en) | 1985-12-16 |
| DE3418643C2 (en) | 1994-03-24 |
| DE3418643A1 (en) | 1984-11-22 |
| SE8402668D0 (en) | 1984-05-17 |
| ES8603583A1 (en) | 1985-12-16 |
| FR2546182A1 (en) | 1984-11-23 |
| SE8402668L (en) | 1984-11-19 |
| IT1179669B (en) | 1987-09-16 |
| GB8412791D0 (en) | 1984-06-27 |
| FR2546182B1 (en) | 1989-02-17 |
| IT8467492A0 (en) | 1984-05-17 |
| GB2141739B (en) | 1986-04-09 |
| JPS59211519A (en) | 1984-11-30 |
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