JPH032204B2 - - Google Patents
Info
- Publication number
- JPH032204B2 JPH032204B2 JP4953483A JP4953483A JPH032204B2 JP H032204 B2 JPH032204 B2 JP H032204B2 JP 4953483 A JP4953483 A JP 4953483A JP 4953483 A JP4953483 A JP 4953483A JP H032204 B2 JPH032204 B2 JP H032204B2
- Authority
- JP
- Japan
- Prior art keywords
- molten iron
- concentration
- heat source
- converter
- ore
- 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 - Lifetime
Links
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 143
- 229910052742 iron Inorganic materials 0.000 claims description 71
- 229910052717 sulfur Inorganic materials 0.000 claims description 28
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 25
- 239000011593 sulfur Substances 0.000 claims description 25
- 238000007670 refining Methods 0.000 claims description 24
- 239000002994 raw material Substances 0.000 claims description 23
- 238000000034 method Methods 0.000 claims description 21
- 239000002893 slag Substances 0.000 claims description 16
- 238000002844 melting Methods 0.000 claims description 11
- 230000008018 melting Effects 0.000 claims description 11
- 239000000463 material Substances 0.000 claims description 10
- 229910044991 metal oxide Inorganic materials 0.000 claims description 9
- 150000004706 metal oxides Chemical class 0.000 claims description 9
- 238000003723 Smelting Methods 0.000 claims description 5
- 238000005261 decarburization Methods 0.000 claims description 4
- 239000003245 coal Substances 0.000 description 22
- 239000000571 coke Substances 0.000 description 18
- 239000011651 chromium Substances 0.000 description 15
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 14
- 229910000831 Steel Inorganic materials 0.000 description 13
- 229910052804 chromium Inorganic materials 0.000 description 13
- 239000010959 steel Substances 0.000 description 13
- 238000007664 blowing Methods 0.000 description 11
- 229910052751 metal Inorganic materials 0.000 description 8
- 239000002184 metal Substances 0.000 description 8
- 238000002474 experimental method Methods 0.000 description 6
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 5
- 229910052799 carbon Inorganic materials 0.000 description 5
- 229910001882 dioxygen Inorganic materials 0.000 description 5
- 229910052748 manganese Inorganic materials 0.000 description 5
- 239000011572 manganese Substances 0.000 description 5
- 239000000843 powder Substances 0.000 description 5
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 4
- 238000006477 desulfuration reaction Methods 0.000 description 4
- 230000023556 desulfurization Effects 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 238000002347 injection Methods 0.000 description 4
- 239000007924 injection Substances 0.000 description 4
- 229910001021 Ferroalloy Inorganic materials 0.000 description 3
- 229910052710 silicon Inorganic materials 0.000 description 3
- 239000010935 stainless steel Substances 0.000 description 3
- 229910001220 stainless steel Inorganic materials 0.000 description 3
- 239000012159 carrier gas Substances 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000007598 dipping method Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000003009 desulfurizing effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 238000005978 reductive desulfurization reaction Methods 0.000 description 1
- 230000002829 reductive effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 230000007704 transition Effects 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
- C21C5/28—Manufacture of steel in the converter
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
Description
【発明の詳細な説明】
この発明はステンレス鋼や各種合金鉄等の溶製
のために転炉容器内の溶鉄中へ多量のスクラツプ
や鉄鉱石、クロム鉱石等の金属酸化物鉱石を添加
して溶解あるいは還元精錬する方法に関し、特に
熱源として石炭やコークス等の硫黄含有量の高い
原料を用いる場合の精錬方法に関するものであ
る。
通常の製鋼過程としての転炉精錬においては、
溶鉄中のＣ、Si、Mn、Ｐ等が熱源として機能し、
これらの酸化熱により溶鉄温度がほぼ充分に補償
される。しかしながらステンレス鋼や各種合金鉄
等の溶製のために転炉容器内の溶鉄中にスクラツ
プ、あるいは鉄鉱石、クロム鉱石、マンガン鉱石
その他の金属酸化物鉱石を大量に添加して、それ
らの溶解、還元を行なわせる場合には溶銑中に含
まれる熱源だけでは熱不足となり、溶銑が転炉容
器内で固化してしまうおそれがあるから、このよ
うな場合には別途熱源原料を溶銑中に供給して、
スクラツプや鉄鉱石、クロム鉱石などの溶解、還
元に必要な熱量を補償する必要がある。このよう
な熱源原料としては酸化発熱量の大きい金属例え
ばAl、Si、あるいはそれらを含む合金を用いる
ことが考えられるが、これらはいずれも価格が高
く、経済的に不利であるため実操業には不適当で
ある。一方、石炭やコークスなどを熱源原料とし
て使用でき、これらはAlやSiと比較して価格が
約1/10と著しく安価であり、しかも容易に大量入
手可能であるから、実操業に使用する熱源原料と
して最も適当である。しかしながら石炭やコーク
スは通常約0.5％程度の硫黄分を含有しており、
したがつてこれらを転炉内溶鉄中に添加した場合
溶鉄中へ硫黄が移行して溶鉄中Ｓ濃度の上昇を招
き、製品材質を著しく劣化させる問題がある。
上述のような転炉精錬時における熱源原料とし
ての石炭やコークスの添加による溶鉄中Ｓ濃度増
加の問題を解決する方法としては、Ｓ濃度が上昇
した溶鉄中へCaO等の脱硫剤を添加し、ArやN2
などの不活性ガスで撹拌する還元脱硫法を適用す
ることが考えられるが、この方法では多量の脱硫
剤、撹拌ガスを使用するため経済的な不利益を招
く欠点がある。
したがつて転炉精錬時の熱源として石炭、コー
クスなど硫黄含有量の高い原料を使用する場合に
は、その熱源原料中の硫黄が溶鉄中へ移行して溶
鉄中Ｓ濃度の上昇を招くことを根本的に防止し得
る精錬法を開発することが鋼生産原単位を低減す
るために必要不可欠点である。
この発明は以上の事情を背景としてなされたも
ので、転炉精錬時に石炭やコークスの如く硫黄含
有量の高い熱源原料を用いる場合において、脱硫
処理等の付加的処理を伴うことなく、溶鉄中Ｓ濃
度の上昇を防止し、これによつて低コストでＳ濃
度の低い鋼が得られるようにすることを目的とす
るものである。
すなわち本発明者等は上述の目的を達成するべ
く鋭意実験・研究を重ねたところ、転炉精錬時に
石炭やコークスなどの硫黄含有量の高い熱源原料
を転炉内溶湯中に添加した場合でも、溶鉄中Ｃ濃
度が２％以上の未だＣ濃度が高い段階では溶鉄中
Ｓ濃度がほとんど上昇しないことを見出し、この
発明をなすに至つたのである。
したがつてこの発明の転炉精錬方法は、転炉容
器内溶鉄中にスクラツプおよび／または鉄鉱石、
クロム鉱石その他の金属酸化物鉱石を添加してそ
れらの溶解、還元を行ない、かつ熱源として石炭
やコークスなどの硫黄含有量の高い原料を供給す
る精錬法において、溶鉄中Ｃ濃度が２％以上の段
階で熱源原料の添加とスクラツプ、金属酸化物鉱
石の溶解、還元とを終了させ、かつ同じく溶鉄中
Ｃ濃度が２％以上の時点で一旦転炉容器内の溶滓
のみを排出させ、その後は硫黄含有量の高い熱源
原料を実質的に添加することなく脱炭吹錬するこ
とを特徴とするものである。
以下この発明の精錬法についてさらに詳細に説
明する。
先ずこの発明をなすに至つた知見について説明
すると、本発明者等は、５トン小型転炉を用い、
その転炉容器内へ多量のスクラツプを添加して容
解する精錬および該溶湯中へ鉄鉱石、クロム鉱石
を添加して還元する精錬を実施するにあたり、熱
源として微粉炭を16Kg／minの吹込み速度で吹込
む実験を行ない、溶鉄中のＳ濃度、Ｃ濃度の経時
変化を調べたところ、第１図に示すような結果が
得られた。この結果から溶鉄中のＳ濃度は精錬末
期の溶鉄中Ｃ濃度が低くなつた段階で急激に上昇
することがわかる。さらに本発明者等は、前記同
様に大量のスクラツプ溶解および鉄鉱石、クロム
鉱石の還元時に熱源として石炭、コークスなどを
使用する種々の精錬実験を、５トン小型転炉を用
いて行ない、種々の溶鉄中Ｃ濃度における熱源原
料中の硫黄の溶鉄中への移行率すなわち
（溶鉄中Ｓ濃度の増加量）／（添加した熱源原料
中のＳ）×100
を調べたところ、、第２図に示す結果が得られた。
但しこの実験におけるスラグ塩基度CaO／SiO2
は2.5〜3.0程度である。
第２図から、熱源原料中の硫黄に起因する溶鉄
中Ｓ濃度の上昇は溶鉄中Ｃ濃度と密接に関係し、
溶鉄中Ｃ濃度が２％未満では溶鉄中Ｓ濃度の上昇
が溶鉄中Ｃ濃度と逆比例関係にあり、一方溶鉄中
Ｃ濃度が２％以上ではほとんど溶鉄中Ｓ濃度が上
昇しないことが判明した。このように溶鉄中Ｃ濃
度が２％以上で溶鉄中Ｓ濃度が上昇しない現象
は、溶鉄中Ｃ濃度が２％以上ではスラグ−メタル
間のＳ分配比がスラグ側に大きく傾き、スラグ中
に熱源原料からの硫黄が溜るためと考えられる。
実際、本発明者等の実験によれば、溶鉄中Ｃ濃度
が２％以上では、溶鉄中Ｓ濃度は上昇しないもの
の、スラグ中のＳ濃度は上昇することが確認され
ている。
以上のような新規な知見から、本発明者等は、
溶鉄中Ｃ濃度が２％以上の段階で石炭、コークス
等の硫黄含有量の高い熱源原料の添加とスクラツ
プの溶解および／または鉄鉱石、クロム鉱石、マ
ンガン鉱石の還元精錬を終了させて、同じく溶鉄
中Ｃ濃度が２％以上の時点で硫黄含有量の高い溶
滓を一旦排出し、その後は前述のような硫黄含有
量の大きい石炭、コークス等の熱源原料を実質的
に添加することなく通常の脱炭吹錬を行つて溶鉄
中Ｃ濃度を２％よりも充分に低い値まで低減させ
る方法を採用することにより、熱源原料中の硫黄
が溶鉄中に移行することを防止して、特に脱硫処
理を施すことなくＳ濃度の低い鋼を得ることが可
能となることを見出し、この発明を完成させたの
である。
上述のようにこの発明の精錬法では石炭、コー
クス等の熱源原料の添加と、スクラツプの溶解、
鉄鉱石、クロム鉱石等の金属酸化物鉱石の還元精
錬を溶鉄中Ｃ濃度が２％未満の値まで低下しない
うちに終了させる必要がある。そのためには、例
えば予め溶鉄中に石炭、コークス等を添加して溶
鉄温度を所要温度まで上昇させた後、スクラツプ
や鉱石を添加してその溶解還元を溶鉄中Ｃ濃度２
％以上の時点で終了させれば良い。また鉱石の還
元を行なわず、スクラツプの溶解のみの場合に
は、石炭、コークス等の添加をスクラツプの溶解
と並行して行ない、両者を溶鉄中Ｃ濃度２％以上
の時点で終了させても良い。一方石炭、コークス
等の熱源原料の添加方法は従来公知の方法に従え
ば良く、例えば転炉容器の底に予め羽口を設けて
おき、その羽口から熱源原料の粉末を吹込んだ
り、あるいは転炉容器内溶鉄中にその上方から浸
漬管を浸漬させ、その浸漬管を介して溶鉄中に粉
末状の熱源原料を吹込んだりすれば良い。またい
ずれの場合も石炭やコークス等の熱源原料の吹込
みと併せて、酸素ガスを溶鉄中に吹込むことによ
りそれらの熱源原料の酸化燃焼を助長させること
が望ましい。但し鉄鉱石やクロム鉱石等の還元精
錬の場合には、酸素ガスの吹込みは還元を阻害す
るから、前述のように予め熱源原料の添加（吹込
み）と酸素ガスの吹込みを行つておき、その後酸
素ガスの吹込みを停止させて還元精錬を行う必要
がある。
転炉容器内の溶滓の排出は前記同様に溶鉄中Ｃ
濃度が２％以上の時点で行う必要がある。溶鉄中
Ｃ濃度が２％よりも低下した時点で排滓すれば、
それまでの間に溶鉄中Ｓ濃度が上昇してしまう。
なお排滓方法は従来一般の排滓方法と同様に転炉
を傾倒させて行えば良い。
排滓後の脱炭吹錬は通常の吹錬方法にしたがつ
て、底吹き羽口および／または上吹きランスによ
つて酸素ガスを吹込んで行なえば良い。
以下この発明の実施例を記す。
実施例
炉底に６本の羽口を有する５トン小型底吹き転
炉に5.5トンの溶銑を装入し、４本の羽口からO2
ガスを50Nm3／minの流量で鋼浴中に吹込み、か
つ１本の羽口から搬送ガスとしてのN2ガス5N
m3／minとともに平均硫黄含有量0.4％の石炭粉
を72Kg／minの速度で鋼浴中に吹込むことによつ
て鋼浴温度を1300℃から1650℃まで昇温させた
後、残りの１本の羽口から搬送ガスとしてのN2
ガス5Nm3／minとともにクロム鉱石粉を62Kg／
minの速度で鋼浴中へ42分間吹込んだ。続いて転
炉容器内の溶滓を排出し、引続き約13分間脱炭吹
錬を行つた。
この実施例における溶鋼中Ｓ濃度、Ｃ濃度、
Cr濃度の推移を第３図に示す。
第３図に示すようにクロム鉱石還元精錬後の排
滓直前における溶鋼中Ｃ濃度は2.2％であつて、
この時点における溶鋼中Ｓ濃度は0.006％であつ
た。そしてその後の脱炭吹錬終了時における溶鋼
中Ｓ濃度も0.005％と、転炉装入前の母溶湯のＳ
濃度とほぼ同程度であつた。したがつて石炭粉中
の硫黄に起因する溶鋼中Ｓ濃度の上昇を完全に抑
制し得たことが明らかである。
以上の説明で明らかなようにこの発明の転炉精
錬方法によれば、石炭やコークスの如く安価では
あるが硫黄含有量の高い原料を転炉精錬における
熱源として用いた場合に、その熱源原料中の硫黄
が溶鉄中に移行して溶鉄中Ｓ濃度が上昇すること
を有効に防止でき、したがつてステンレス鋼や各
種合金鉄等の溶製のために溶鉄中に大量のスクラ
ツプを添加して溶解する精錬および鉄鉱石、クロ
ム鉱石、マンガン鉱石その他の金属酸化物鉱石を
添加して還元する精錬においてそれらの溶解、還
元後に脱硫処理を改めて行う必要がなく、したが
つて脱硫処理に要するコストを不要にして鋼生産
原単位を顕著に低減し得る効果が得られる。 [Detailed Description of the Invention] This invention involves adding a large amount of scrap and metal oxide ores such as iron ore and chromium ore to molten iron in a converter vessel in order to melt stainless steel and various ferroalloys. The present invention relates to a method of melting or reduction refining, and particularly relates to a refining method when a raw material with a high sulfur content such as coal or coke is used as a heat source. In converter refining as a normal steelmaking process,
C, Si, Mn, P, etc. in molten iron function as a heat source,
These oxidation heats almost fully compensate for the molten iron temperature. However, in order to melt stainless steel and various ferroalloys, etc., large amounts of scrap or iron ore, chromium ore, manganese ore, and other metal oxide ores are added to the molten iron in the converter vessel, and the melting and When performing reduction, there is a risk that the heat source contained in the hot metal alone will not provide enough heat and the hot metal will solidify in the converter vessel. hand,
It is necessary to compensate for the amount of heat required to melt and reduce scrap, iron ore, chrome ore, etc. Metals with a large oxidation calorific value, such as Al, Si, or alloys containing them, may be used as such heat source raw materials, but these are all expensive and economically disadvantageous, so they are not suitable for actual operation. It's inappropriate. On the other hand, coal, coke, etc. can be used as heat source raw materials, and these are extremely cheap at about 1/10 of Al and Si, and can be easily obtained in large quantities, so they are not suitable for use as heat sources in actual operations. Most suitable as a raw material. However, coal and coke usually contain about 0.5% sulfur.
Therefore, when these are added to the molten iron in the converter, sulfur migrates into the molten iron, resulting in an increase in the S concentration in the molten iron, and there is a problem in that the quality of the product material deteriorates significantly. As a method to solve the above-mentioned problem of increased S concentration in molten iron due to the addition of coal or coke as a heat source material during converter refining, a desulfurizing agent such as CaO is added to the molten iron where the S concentration has increased. Ar or N2
It is conceivable to apply a reductive desulfurization method that involves stirring with an inert gas such as, but this method has the drawback of using a large amount of desulfurization agent and stirring gas, resulting in an economic disadvantage. Therefore, when using raw materials with high sulfur content such as coal or coke as a heat source during converter refining, it is important to note that the sulfur in the heat source raw materials may migrate into the molten iron, leading to an increase in the S concentration in the molten iron. It is essential to develop a refining method that can fundamentally prevent steel production. This invention was made against the background of the above-mentioned circumstances, and when using heat source raw materials with high sulfur content such as coal or coke during converter refining, it is possible to eliminate sulfur in molten iron without any additional treatment such as desulfurization treatment . The purpose of this is to prevent the concentration from increasing, thereby making it possible to obtain steel with a low S concentration at low cost. In other words, the present inventors have conducted extensive experiments and research to achieve the above-mentioned objective, and have found that even when heat source raw materials with high sulfur content such as coal and coke are added to the molten metal in the converter during converter refining, It was discovered that the S concentration in molten iron hardly increases when the C concentration in molten iron is still high, such as 2% or more , and this invention was achieved. Therefore, in the converter refining method of the present invention, scrap and/or iron ore,
In a smelting method in which chromium ore and other metal oxide ores are added to dissolve and reduce them, and raw materials with high sulfur content such as coal and coke are supplied as a heat source, the C concentration in the molten iron is 2% or more. At this stage, the addition of heat source raw materials, scrapping, and melting and reduction of metal oxide ores are completed, and when the C concentration in the molten iron reaches 2% or more, only the slag in the converter vessel is discharged. It is characterized by decarburizing and blowing without substantially adding heat source raw materials with high sulfur content. The refining method of the present invention will be explained in more detail below. First, to explain the knowledge that led to this invention, the inventors used a 5-ton small converter,
Pulverized coal is injected at 16 kg/min as a heat source during refining, which involves adding a large amount of scrap into the converter vessel to dissolve it, and refining, which involves adding iron ore and chromium ore to the molten metal for reduction. When we conducted an experiment in which the molten iron was injected at a high speed and investigated the changes in the S and C concentrations in the molten iron over time, we obtained the results shown in Figure 1. This result shows that the S concentration in molten iron rapidly increases at the end of refining, when the C concentration in molten iron becomes low. Furthermore, the present inventors conducted various refining experiments using a 5-ton small converter using coal, coke, etc. as a heat source during large-scale scrap melting and reduction of iron ore and chromium ore using a 5-ton small converter. The transfer rate of sulfur in the heat source raw material into the molten iron at the C concentration in the molten iron, that is, (increase in the S concentration in the molten iron)/(S in the added heat source raw material) x 100, was investigated, and the results are shown in Figure 2. The results were obtained.
However, in this experiment, the slag basicity CaO/SiO 2
is about 2.5 to 3.0. From Figure 2, the increase in S concentration in molten iron due to sulfur in the heat source raw material is closely related to the C concentration in molten iron.
It was found that when the C concentration in molten iron is less than 2%, the increase in the S concentration in molten iron is inversely proportional to the C concentration in molten iron, whereas when the C concentration in molten iron is 2% or more, the S concentration in molten iron hardly increases. The reason why the S concentration in the molten iron does not increase when the C concentration in the molten iron is 2% or more is that when the C concentration in the molten iron is 2% or more, the S distribution ratio between slag and metal tilts greatly toward the slag, and a heat source is created in the slag. This is thought to be due to accumulation of sulfur from raw materials.
In fact, according to experiments conducted by the present inventors, it has been confirmed that when the C concentration in the molten iron is 2% or more, the S concentration in the molten iron does not increase, but the S concentration in the slag increases. Based on the above novel findings, the present inventors
When the C concentration in the molten iron is 2% or more, the addition of heat source materials with high sulfur content such as coal and coke, the melting of scrap, and/or the reduction refining of iron ore, chromium ore, and manganese ore are completed, and the same molten iron is produced. When the medium C concentration is 2% or more, the slag with a high sulfur content is discharged, and then the slag with a high sulfur content is discharged as usual without substantially adding heat source raw materials such as coal and coke with a high sulfur content as described above. By adopting a method of decarburizing blowing to reduce the C concentration in molten iron to a value well below 2%, it is possible to prevent sulfur in the heat source raw material from migrating into molten iron, and to reduce the carbon concentration in molten iron. They discovered that it was possible to obtain steel with a low S concentration without undergoing any process, and completed this invention. As mentioned above, the refining method of this invention involves adding heat source materials such as coal and coke, melting scrap,
It is necessary to complete the reduction refining of metal oxide ores such as iron ore and chromium ore before the C concentration in molten iron decreases to a value of less than 2%. To do this, for example, add coal, coke, etc. to the molten iron in advance to raise the molten iron temperature to the required temperature, and then add scrap or ore to reduce the dissolution and reduce the C concentration in the molten iron.
It is sufficient to terminate the process when it reaches % or more. If the ore is not reduced and only the scrap is melted, coal, coke, etc. may be added in parallel with the scrap melting, and both may be terminated when the C concentration in the molten iron reaches 2% or more. . On the other hand, the method of adding heat source raw materials such as coal and coke can be done in accordance with conventionally known methods. For example, tuyeres may be provided in advance at the bottom of the converter vessel and the heat source raw material powder may be injected through the tuyeres, or A dipping tube may be immersed into the molten iron in the converter vessel from above, and a powdered heat source material may be blown into the molten iron through the dipping tube. In any case, it is desirable to inject oxygen gas into the molten iron together with the injection of heat source materials such as coal or coke to promote oxidative combustion of those heat source materials. However, in the case of reduction refining of iron ore, chromium ore, etc., the injection of oxygen gas inhibits the reduction, so it is necessary to add (inject) the heat source raw material and inject the oxygen gas in advance as described above. After that, it is necessary to stop the injection of oxygen gas and perform reduction refining. The molten slag in the converter vessel is discharged as described above .
It is necessary to carry out the test when the concentration is 2% or more. If the slag is discharged when the C concentration in the molten iron falls below 2%,
Until then, the S concentration in the molten iron will increase.
Note that the slag removal method may be carried out by tilting the converter in the same manner as the conventional general slag removal method. Decarburization blowing after slag removal may be carried out by blowing oxygen gas through a bottom blowing tuyere and/or top blowing lance according to a normal blowing method. Examples of this invention will be described below. Example: 5.5 tons of hot metal is charged into a 5-ton small bottom-blowing converter having 6 tuyeres at the bottom of the furnace, and O 2 is discharged from the 4 tuyeres.
Gas is blown into the steel bath at a flow rate of 50Nm 3 /min, and 5N of N 2 gas is supplied as a carrier gas through one tuyere.
After raising the steel bath temperature from 1300°C to 1650°C by blowing coal powder with an average sulfur content of 0.4% into the steel bath at a rate of 72 kg/min with m 3 /min, the remaining 1 N2 as carrier gas from book tuyeres
Chromium ore powder 62Kg/min with gas 5Nm 3 /min
It was blown into the steel bath for 42 minutes at a rate of min. Subsequently, the slag in the converter vessel was discharged, and decarburization blowing continued for approximately 13 minutes. S concentration in molten steel in this example, C concentration,
Figure 3 shows the change in Cr concentration. As shown in Figure 3, the C concentration in the molten steel immediately before the slag after chromium ore reduction smelting is 2.2%.
At this point, the S concentration in the molten steel was 0.006%. The S concentration in the molten steel at the end of the subsequent decarburization blowing was 0.005%, and the S concentration in the mother molten metal before charging into the converter was 0.005%.
The concentration was approximately the same. Therefore, it is clear that the increase in S concentration in molten steel caused by sulfur in coal powder could be completely suppressed. As is clear from the above explanation, according to the converter refining method of the present invention, when an inexpensive raw material with high sulfur content, such as coal or coke, is used as a heat source in converter refining, This can effectively prevent sulfur from moving into the molten iron and increasing the S concentration in the molten iron. Therefore, for melting stainless steel and various ferroalloys, etc., it is necessary to add a large amount of scrap to the molten iron for melting. There is no need to perform desulfurization treatment again after dissolving and reducing iron ore, chromium ore, manganese ore, and other metal oxide ores during smelting and reduction by adding iron ore, chromium ore, manganese ore, and other metal oxide ores, thus eliminating the cost required for desulfurization treatment. Thus, the effect of significantly reducing the steel production unit consumption can be obtained.
第１図は５トン小型転炉での石炭粉吹込み実験
における溶鉄中Ｃ濃度、Ｓ濃度の経時変化を示す
グラフ、第２図は同じく５トン小型転炉において
大量のスクラツプ、鉄鉱石、クロム鉱石を添加し
て精錬しかつ石炭、コークスを熱源として添加し
た場合における熱源原料中硫黄の溶鉄中への移行
率と溶鉄中Ｃ濃度との関係を示す相関図、第３図
はこの発明の実施例における溶鉄中Ｃ、Ｓ、Cr
の推移を示すグラフである。
Figure 1 is a graph showing changes over time in C and S concentrations in molten iron in a coal powder injection experiment conducted in a small 5-ton converter, and Figure 2 is a graph showing large amounts of scrap, iron ore, and chromium in a small 5-ton converter. Figure 3 is a correlation diagram showing the relationship between the transfer rate of sulfur in the heat source raw material to the molten iron and the C concentration in the molten iron when ore is added and refined and coal and coke are added as a heat source. C , S , Cr in molten iron in examples
It is a graph showing the transition of.
Claims (1)
び／または金属酸化物鉱石を添加してそれらの溶
解および／または還元精錬を行ない、かつその溶
解および／または還元精錬の熱源として硫黄含有
量の高い熱源原料を添加する精錬法において、 前記熱源原料の添加と前記スクラツプおよび／
または金属酸化物鉱石の溶解および／または還元
を、溶鉄中Ｃ濃度が２％以上の段階で終了させ、
かつ溶鉄中Ｃ濃度が２％以上の時点で転炉容器内
の溶滓のみを排出させ、その後は前記硫黄含有量
の高い熱源原料を実質的に添加することなく、脱
炭精錬を行うことを特徴とする転炉精錬法。[Claims] 1. Adding a large amount of scrap and/or metal oxide ore to molten iron in a converter vessel and melting and/or reducing the smelting, and providing a heat source for the melting and/or reduction smelting. In a refining method in which a heat source material with a high sulfur content is added as a heat source material, the addition of the heat source material and the scrap and/or
or dissolving and/or reducing the metal oxide ore at a stage where the C concentration in the molten iron is 2% or more,
In addition, when the C concentration in the molten iron reaches 2% or more, only the slag in the converter vessel is discharged, and thereafter, decarburization refining is performed without substantially adding the heat source raw material with a high sulfur content. Characteristic converter refining method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58049534A JPS59173214A (en) | 1983-03-24 | 1983-03-24 | Converter refining method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58049534A JPS59173214A (en) | 1983-03-24 | 1983-03-24 | Converter refining method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS59173214A JPS59173214A (en) | 1984-10-01 |
| JPH032204B2 true JPH032204B2 (en) | 1991-01-14 |
Family
ID=12833823
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP58049534A Granted JPS59173214A (en) | 1983-03-24 | 1983-03-24 | Converter refining method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS59173214A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109136451B (en) * | 2018-08-13 | 2020-07-14 | 林州凤宝管业有限公司 | A method of reducing iron consumption |
-
1983
- 1983-03-24 JP JP58049534A patent/JPS59173214A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS59173214A (en) | 1984-10-01 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP2575827B2 (en) | Manufacturing method of ultra low carbon steel for continuous casting with excellent cleanliness | |
| JP4736466B2 (en) | Method for producing high chromium molten steel | |
| KR850000927B1 (en) | Method for preventing slopping during subsurface pneumatic refining steel | |
| JP2964861B2 (en) | Stainless steel manufacturing method | |
| JP4765374B2 (en) | Desulfurization treatment method for chromium-containing hot metal | |
| KR910009962B1 (en) | Method for manufacturing low chromium-containing molten iron | |
| US3607227A (en) | Production of spheroidal graphite irons | |
| JPH07316618A (en) | Pre-refining method for molten reduced hot metal | |
| JPH0297611A (en) | Method for melting cold iron source | |
| JP4759832B2 (en) | Hot phosphorus dephosphorization method | |
| JP2802799B2 (en) | Dephosphorization and desulfurization method for crude molten stainless steel and flux used for it | |
| SU1038365A1 (en) | Method for smelting high-chromium alloys and master alloys and charge for carrying out the method | |
| JPH0959708A (en) | Efficient decarburization blowing method for stainless steel | |
| SU1216216A1 (en) | Method of alloying steel | |
| SU1687627A1 (en) | Method of melting steel with up to 5% chromium | |
| JPS59173214A (en) | Converter refining method | |
| JP2002515545A (en) | Integrated desulfurization method for hot metal and steel | |
| SU691497A1 (en) | Method of steel smelting | |
| JPH0260723B2 (en) | ||
| JPH0551616A (en) | Method for producing low S and low P hot metal | |
| SU992592A1 (en) | Method for smelting steel in acid open-hearth furnaces | |
| US4780133A (en) | Process to improve the refining of liquid metals by natural gas injection | |
| JP2764339B2 (en) | Method of treating hot metal for high chromium low P low S steel | |
| SU378416A1 (en) | METHOD OF MANUFACTURE OF CARBON AND LOW-ALLOY STEEL | |
| JPS61106744A (en) | Melting and manufacturing method of stainless steel |