JPS6123844B2 - - Google Patents
Info
- Publication number
- JPS6123844B2 JPS6123844B2 JP11477879A JP11477879A JPS6123844B2 JP S6123844 B2 JPS6123844 B2 JP S6123844B2 JP 11477879 A JP11477879 A JP 11477879A JP 11477879 A JP11477879 A JP 11477879A JP S6123844 B2 JPS6123844 B2 JP S6123844B2
- Authority
- JP
- Japan
- Prior art keywords
- furnace
- gas
- furnace mouth
- area ratio
- mouth area
- 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
- 239000007789 gas Substances 0.000 claims description 88
- 238000007670 refining Methods 0.000 claims description 20
- 229910000831 Steel Inorganic materials 0.000 claims description 19
- 239000010959 steel Substances 0.000 claims description 19
- 229910001220 stainless steel Inorganic materials 0.000 claims description 14
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 12
- 239000001301 oxygen Substances 0.000 claims description 12
- 229910052760 oxygen Inorganic materials 0.000 claims description 12
- 238000007664 blowing Methods 0.000 claims description 9
- 238000006243 chemical reaction Methods 0.000 claims description 7
- 238000004519 manufacturing process Methods 0.000 claims description 7
- 238000002347 injection Methods 0.000 claims description 5
- 239000007924 injection Substances 0.000 claims description 5
- 230000003247 decreasing effect Effects 0.000 claims description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 31
- 229910052757 nitrogen Inorganic materials 0.000 description 16
- 238000000034 method Methods 0.000 description 13
- 239000011261 inert gas Substances 0.000 description 9
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 6
- 238000005261 decarburization Methods 0.000 description 6
- 229910052804 chromium Inorganic materials 0.000 description 5
- 239000011651 chromium Substances 0.000 description 5
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 4
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 4
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 4
- 229910002091 carbon monoxide Inorganic materials 0.000 description 4
- 229910052786 argon Inorganic materials 0.000 description 3
- 238000007796 conventional method Methods 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 230000002265 prevention Effects 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 2
- 239000000292 calcium oxide Substances 0.000 description 2
- 235000012255 calcium oxide Nutrition 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 239000010436 fluorite Substances 0.000 description 2
- 238000005187 foaming Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000007935 neutral effect Effects 0.000 description 2
- 239000002893 slag Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910000967 As alloy Inorganic materials 0.000 description 1
- 229910000519 Ferrosilicon Inorganic materials 0.000 description 1
- 241001062472 Stokellia anisodon Species 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 238000009529 body temperature measurement Methods 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 238000003756 stirring Methods 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
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
Description
この発明は、酸素上吹転炉製鋼において、大気
の炉内侵入を防止して窒素含有の低減を図つた高
クロム鋼の製造法に関する。
Cr5〜30％を含有する合金鋼、フエライト系あ
るいはオーステナイト系ステンレス鋼などの高ク
ロム鋼の溶製は、クロムが酸化されやすい元素で
あるため、従来単一の炉で精錬することは困難と
されていた。
たとえば、高クロム鋼は通常転炉又は電気炉に
よつて粗脱炭あるいは精錬された溶鋼にクロム系
合金鉄及び他の添加物を加え、それらを溶解させ
た後とりべ内で真空保持して酸素吹錬する方法
（VOD法）や希釈酸素横吹炉で吹錬する方法
（AOD法）で溶製されていた。しかし、このよう
に２種類の炉を用いる溶製法は、設備費、作業工
数、熱効率、歩留などからみて必ずしも経済的な
方法とはいえない。
一方酸素上吹転炉製鋼においても、溶銑の強い
撹拌が保障されるならば、高炭素領域（0.5％Ｃ
以上）においてクロムの酸化を少なくして脱炭反
応を促進することができ、又炉底からたとえば不
活性ガスの吹込みを行ない脱炭反応によつて生成
する一酸化炭素ガスの希釈を行なえば、0.3％Ｃ
以下の低炭素領域でも脱炭反応が促進できるか
ら、これを利用して炉底にガス吹込みノズルを有
する酸素上吹転炉により高クロム鋼を溶製するこ
とができる。
しかしながら、そのときの窒素挙動については
不明な点が多く、精錬中の脱炭反応や炉底ノズル
から吹込む不活性、中性、一酸化炭素、二酸化炭
素等のガスとの関係、及び炉口形状との対応も十
分に解明されておらず、この溶製法により低窒素
鋼が確実に得られるとはいゝがたい。
この発明は、かかる現状に鑑み、炉底にガス吹
込みノズルを有する酸素上吹転炉において、炉内
反応により発生するガス及びノズルより吹込まれ
る不活性ガス等の全ガス総量と、炉口面積比（こ
こで炉口面積比とは精錬炉の炉内から発生するガ
スが通過するか、又は炉内へ大気が通過し得る炉
口面積の溶鋼１トン当りの値をいう）との相関関
係を明らかにし、炉口周辺から大気が炉内に侵入
するのを防止するために、全ガス総量に応じたガ
スの通過する炉口面積比を決定し、大気の炉内侵
入による溶鋼の窒素吸収を防止し、窒素含有の低
減を図つた高クロム鋼の製造法を提案するもので
ある。
この発明は、浴面下にガス吹込みノズルを有す
る酸素上吹転炉により、浴中にガスを吹込みなが
ら酸素ランスより酸素を浴面に供給して行う鋼の
精錬において、炉内反応による発生ガス及びノズ
ルより吹込むガス等の全ガス総量に応じてガスの
通過する炉口面積比を変化させ、炉口から排出さ
れるガスの流速を確保して炉口周縁から炉内への
大気侵入を防止し、窒素の低減を図つた高クロム
鋼の製造法を要旨とする。
精錬中に炉内から発生する総ガス量は精錬中の
時期により変化するため、炉口付近におけるガス
の流動は複雑である。そして、総ガス量が、炉口
の開口特性により決まるガス流量より少なくなる
精錬末期には、炉口周辺の大気が炉内に侵入す
る。したがつて、大気の炉内侵入を防止するに
は、炉口におけるガス流速を上げることが大事で
あり、そのため炉口面積比を小さくするか、ある
いは総ガス量を増大させる必要がある。
しかし、炉口面積比が小さすぎる場合には、炉
内の溶鋼が急激な反応を生じたり、又炉内のスラ
グや溶鋼の発泡、飛散により炉口が閉塞される恐
れがあるため、炉口は操業上適正な炉口面積比を
保つ必要がある。
高クロム鋼の精錬においては、脱炭期の比較的
総ガス量の多い時期には問題はないが、脱炭後期
から還元仕上期の比較的総ガス量の少ない時期に
は、スラグや溶鋼の急激な発泡や飛散が少ないた
め、炉口面積比を小さくすることが大気侵入防止
に有効であり、ノズルより吹込まれる不活性ガス
を排出するに十分な炉口面積比があればよい。
そこで、本発明者らは総ガス量と炉口面積比と
の相関関係を明らかにするため種々試験した。そ
の結果について以下に説明する。
第１図は炉口面積比σと総ガス量Ｇとの関係を
示したものであり、最小炉口面積比σ１において
大気の侵入を防止できる最小総ガス量G1及び最
大炉口面積比σ２において大気の侵入を防止でき
る最小総ガス量G2は図面に示したとおりである
が、σ２やG2は炉容などの炉特性により炉特有
の値を有する。又2.4t炉により実施した結果を第
２図に示す（ガス温度約950℃）。
上記炉口面積比σの決定は、炉内より発生する
総ガス量Ｇを直接装定する方法、あるいは炉口を
通過するガス組成とガス温度を測定し総ガス量Ｇ
を算出する方法により行われる。その算出法の一
例を次に示す。
(1) 総ガス量Ｇの算出の基本となるガスは、炉底
ノズルから吹込まれる不活性ガス（たとえばア
ルゴンガス）であるから、次式によつて求め
る。
Ｇ＝炉底ノズルから吹込む不活性ガス量／炉口を通過す
る不活性ガス濃度（％）×100
(2) 直接総ガス量Ｇを次式により算出する。この
場合には温度と圧力により基準又は管理温度に
補正する必要がある。
Ｇ＝G′×基準ガス温度＋２７３／測定ガス温度＋２７
３×測定ガス圧力／基準ガス圧力
G′＝実測ガス流量
上式により算出した総ガス量Ｇの値により、第
１図に示す大気侵入防止域に炉雰囲気を設定する
ように炉口面積比σを設定するか、あるいは総ガ
ス量の値をG2以上に保つように総ガス量Ｇの増
加を図ればよい。又総ガス量Ｇと炉口面積比σの
相関関係を利用して設定することもできる。
又、総ガス量Ｇと炉口面積比σとの比は、炉口
部におけるガス流速V0に対応する。
V0＝Ｇ／σ（ｍ／min）
そして、第１図における大気侵入域と大気侵入
防止域を決定する直線の勾配の逆数が炉口部にお
けるガス流速に等しい。なお、この場合のガス
は、標準状態に換算した値を用いる。したがつ
て、実際の炉口部におけるガス温度をｔ℃とすれ
ば、真のガス流速Ｖは次式で求まる。
Ｖ＝Ｇ／σ×ｔ＋２７３／２７３ （ｍ／min）
溶鋼からの反応生成ガス（一酸化炭素ガスな
ど）を希釈し、生成ガス分圧を低下させるには、
炉底ノズルより吹込む不活性ガスは、精錬条件及
び操業条件によりある値G1（第１図）以下にす
ることはできないが、炉口を通過する総ガス量が
低下し始める精錬後期においては、炉口周辺から
炉内へ大気が侵入するのを防止するため、総ガス
量はG2以上の値を確保しなければならない。
前記のごとく、この発明は大気の炉内への侵入
を防止するため、炉口面積比を総ガス量に応じて
変化させることを基本とするが、たとえばガス流
速を確保するため炉口面積比を小さくした場合に
は同時に炉底ノズルより吹込む不活性ガスを増加
し総ガス量を増大せしめると、炉内への大気の侵
入防止効果はさらに向上する。
又この発明の実施において、炉口は操業上ある
いは設備上の制約を受け、ある炉口面積比を確保
する必要上炉口面積比を所望大きさまで小さくで
きない場合があるが、この場合は最小炉口面積比
σ１を維持し、かつ炉口周辺の大気が炉内に侵入
するのを防止するには、不活性ガスによる炉口周
辺のガスシールの併用が有効である。又このガス
シールの併用は、上記以外の場合で大気侵入の可
能性が高い場合にみ利用できることはいうまでも
ない。
この発明は、転炉で溶製される高クロム鋼を対
象とするが、酸化されやすい他の鋼、あるいは低
窒素鋼などの製造にも適用できる。又浴面下への
ガスの吹込みはアルゴン、窒素時の不活性又は中
性ガス、さらに二酸化炭素およびもしくは一酸化
炭素を主とするガスを用いてもよい。
次に、この発明の実施例について具体的に説明
する。
実施例 １
炉底に内径８mmのノズル２本を有する2.4トン
転炉に、粗脱炭溶鋼2.4トンを注入し、造滓剤と
して生石灰60Kgと螢石30Kgを添加し、アルゴンガ
スを1Nm3／minの割合でノズルより吹込みなが
ら、送酸速度6Nm3／minで約８分間酸素上吹き吹
錬を行い、その後送酸速度1Nm3／minまで低下さ
せ、約20分間吹錬を行い、その間２分隔で測温
し、かつサンプリングを行つた。その後、フエロ
シリコン66Kg、生石灰133Kg、螢石24Kgを添加し
還元精錬を実施した。
上記精錬中に、この発明の実施により炉口面積
比の調整を行なつた。すなわち、炉口径の異なる
炉蓋の多数を準備し、バツチ的に調整を行ない、
炉特有の総ガス量Ｇと炉口面積比σを求めた。な
お、この実施例における最小炉口面積比σ１は約
５×10-3（m2／ton）でほゞ零に等しく、最大炉
口面積比σ２は0.2（m2／ton）である。
上記精錬操業における各精錬期末における化学
成分を第１表に示す。又、各精錬期における総ガ
ス量Ｇと炉口面積比σに関し、脱窒、吸窒を区別
し、その結果を第２図に示す。この結果より、最
小総ガス量G2は1.0（Ｎm2／min・ton）が得ら
れ、これ以下の総ガス量の場合には、およそ次式
によつて炉口面積比σを求めることができる。
σ＜0.4（Ｇ−0.5）
又最小総ガス量G1は約0.5（Ｎm2／min・ton）
である。
The present invention relates to a method for manufacturing high chromium steel in an oxygen top-blown converter furnace, which prevents atmospheric air from entering the furnace and reduces nitrogen content. Conventionally, it has been difficult to smelt high chromium steels such as alloy steels containing 5 to 30% Cr, ferritic stainless steels, or austenitic stainless steels in a single furnace because chromium is an element that is easily oxidized. was. For example, high chromium steel is usually produced by adding chromium-based alloy iron and other additives to molten steel that has been roughly decarburized or refined in a converter or electric furnace, and after melting them, it is kept under vacuum in a ladle. It was smelted using oxygen blowing method (VOD method) or blowing method in diluted oxygen side blowing furnace (AOD method). However, such a melting method using two types of furnaces is not necessarily an economical method in terms of equipment costs, number of work steps, thermal efficiency, yield, etc. On the other hand, even in oxygen top-blown converter steelmaking, if strong stirring of hot metal is guaranteed, the high carbon range (0.5%C
(above), the decarburization reaction can be promoted by reducing oxidation of chromium, and if inert gas is injected from the bottom of the furnace to dilute the carbon monoxide gas generated by the decarburization reaction. , 0.3%C
Since the decarburization reaction can be promoted even in the low carbon region below, high chromium steel can be produced using an oxygen top blowing converter furnace having a gas injection nozzle at the bottom of the furnace. However, there are many unknowns about the behavior of nitrogen at that time, including the decarburization reaction during refining, the relationship with inert, neutral, carbon monoxide, carbon dioxide, and other gases injected from the furnace bottom nozzle, and the The correspondence with shape has not been fully elucidated, and it is difficult to reliably obtain low-nitrogen steel using this melting method. In view of the current situation, the present invention provides an oxygen top blowing converter having a gas injection nozzle at the bottom of the furnace. Correlation with area ratio (Here, the furnace mouth area ratio refers to the value per ton of molten steel of the furnace mouth area through which gas generated from the inside of the refining furnace can pass or through which the atmosphere can pass into the furnace.) In order to clarify the relationship and prevent air from entering the furnace from around the furnace mouth, we determined the ratio of the area of the furnace mouth through which gas passes according to the total amount of gas, and determined the ratio of the area of the furnace mouth through which the gas passes through, based on the total amount of gas. This paper proposes a method for manufacturing high chromium steel that prevents absorption and reduces nitrogen content. This invention utilizes an in-furnace reaction in steel refining, which is carried out by blowing gas into the bath and supplying oxygen to the bath surface from an oxygen lance using an oxygen top-blown converter having a gas injection nozzle below the bath surface. The furnace mouth area ratio through which gas passes is changed according to the total amount of gas such as the generated gas and the gas injected from the nozzle, and the flow rate of the gas discharged from the furnace mouth is ensured to ensure that the atmosphere flows from the periphery of the furnace mouth into the furnace. This article focuses on a method for manufacturing high chromium steel that prevents nitrogen from entering and reduces nitrogen. Since the total amount of gas generated from inside the furnace during refining changes depending on the time of refining, the flow of gas near the furnace mouth is complicated. At the final stage of refining, when the total gas amount is less than the gas flow rate determined by the opening characteristics of the furnace mouth, the atmosphere around the furnace mouth enters into the furnace. Therefore, in order to prevent atmospheric air from entering the furnace, it is important to increase the gas flow rate at the furnace mouth, and therefore it is necessary to reduce the furnace mouth area ratio or increase the total gas amount. However, if the furnace mouth area ratio is too small, the molten steel in the furnace may cause a rapid reaction, or the furnace mouth may become blocked due to foaming or scattering of slag and molten steel. It is necessary to maintain an appropriate furnace mouth area ratio for operation. In refining high chromium steel, there are no problems during the decarburization stage when the total gas amount is relatively large, but during the period from the late decarburization stage to the reduction finishing stage when the total gas volume is relatively low, slag and molten steel are produced. Since rapid foaming and scattering are small, reducing the furnace mouth area ratio is effective in preventing atmospheric intrusion, and it is sufficient to have a furnace mouth area ratio sufficient to discharge the inert gas blown from the nozzle. Therefore, the present inventors conducted various tests to clarify the correlation between the total gas amount and the furnace mouth area ratio. The results will be explained below. Figure 1 shows the relationship between the furnace mouth area ratio σ and the total gas amount G, and shows the minimum total gas amount G 1 and the maximum furnace mouth area ratio that can prevent atmospheric intrusion at the minimum furnace mouth area ratio σ 1 . The minimum total gas amount G 2 that can prevent air from entering at σ 2 is as shown in the drawing, but σ 2 and G 2 have values specific to each furnace depending on the furnace characteristics such as the furnace volume. Figure 2 shows the results obtained using a 2.4 ton furnace (gas temperature approximately 950°C). The above furnace mouth area ratio σ can be determined by directly determining the total gas amount G generated from inside the furnace, or by measuring the gas composition and gas temperature passing through the furnace mouth.
This is done using a method that calculates An example of the calculation method is shown below. (1) Since the basic gas for calculating the total gas amount G is an inert gas (for example, argon gas) injected from the furnace bottom nozzle, it is calculated using the following formula. G = Amount of inert gas injected from the furnace bottom nozzle/Inert gas concentration (%) passing through the furnace mouth x 100 (2) Calculate the direct total gas amount G using the following formula. In this case, it is necessary to correct the temperature and pressure to the reference or control temperature. G=G'×Reference gas temperature +273/Measurement gas temperature+27
3 x Measured gas pressure/Reference gas pressure G' = Actual gas flow rate Based on the value of the total gas amount G calculated using the above formula, the furnace mouth area ratio σ is set so that the furnace atmosphere is set in the air intrusion prevention area shown in Figure 1. Alternatively, the total gas amount G may be increased so as to maintain the value of the total gas amount G2 or more . It can also be set using the correlation between the total gas amount G and the furnace mouth area ratio σ. Further, the ratio between the total gas amount G and the furnace mouth area ratio σ corresponds to the gas flow velocity V 0 at the furnace mouth. V 0 =G/σ (m/min) The reciprocal of the slope of the straight line that determines the atmosphere intrusion zone and the atmosphere intrusion prevention zone in FIG. 1 is equal to the gas flow velocity at the furnace mouth. Note that the gas in this case uses a value converted to a standard state. Therefore, if the actual gas temperature at the furnace mouth is t°C, the true gas flow velocity V can be determined by the following equation. V=G/σ×t+273/273 (m/min) To dilute reaction product gas (carbon monoxide gas, etc.) from molten steel and lower the product gas partial pressure,
The inert gas injected from the furnace bottom nozzle cannot be lower than a certain value G 1 (Figure 1) depending on the refining and operating conditions, but in the late stage of refining when the total amount of gas passing through the furnace mouth begins to decrease. To prevent air from entering the furnace from around the furnace mouth, the total gas volume must be at least G2 . As mentioned above, this invention is based on changing the furnace mouth area ratio according to the total gas amount in order to prevent atmospheric air from entering the furnace. If the amount of inert gas blown into the furnace bottom nozzle is increased to increase the total amount of gas when the amount of inert gas is decreased, the effect of preventing atmospheric air from entering the furnace can be further improved. In addition, in carrying out the present invention, the furnace opening may be subject to operational or equipment constraints, and it may not be possible to reduce the furnace opening area ratio to a desired size due to the need to secure a certain furnace opening area ratio. In order to maintain the mouth area ratio σ 1 and to prevent the atmosphere around the furnace mouth from entering the furnace, it is effective to use a gas seal around the furnace mouth with an inert gas. It goes without saying that the combined use of this gas seal can only be used in cases other than the above, where there is a high possibility of atmospheric intrusion. Although this invention is directed to high chromium steel melted in a converter, it can also be applied to the production of other easily oxidized steels or low nitrogen steels. Further, for blowing gas below the bath surface, an inert or neutral gas such as argon or nitrogen, or a gas mainly containing carbon dioxide and/or carbon monoxide may be used. Next, embodiments of the present invention will be specifically described. Example 1 2.4 tons of crude decarburized molten steel was injected into a 2.4-ton converter having two nozzles with an inner diameter of 8 mm at the bottom of the furnace, 60 kg of quicklime and 30 kg of fluorite were added as slag-forming agents, and argon gas was added at 1 Nm 3 / While blowing from the nozzle at a rate of Temperature measurements and sampling were performed at 2 minute intervals. After that, 66 kg of ferrosilicon, 133 kg of quicklime, and 24 kg of fluorite were added and reduction refining was performed. During the above refining, the furnace mouth area ratio was adjusted by implementing the present invention. In other words, a large number of furnace lids with different diameters are prepared, and adjustments are made in batches.
The total gas amount G and furnace mouth area ratio σ specific to the furnace were determined. In this example, the minimum furnace mouth area ratio σ 1 is approximately 5×10 -3 (m 2 /ton), which is approximately equal to zero, and the maximum furnace mouth area ratio σ 2 is 0.2 (m 2 /ton). . Table 1 shows the chemical components at the end of each refining period in the above refining operation. Furthermore, regarding the total gas amount G and the furnace mouth area ratio σ in each refining period, denitrification and nitrogen absorption were distinguished, and the results are shown in FIG. From this result, the minimum total gas amount G 2 is 1.0 (Nm 2 /min・ton), and if the total gas amount is less than this, the furnace mouth area ratio σ can be determined approximately by the following formula. can. σ<0.4 (G-0.5) Also, the minimum total gas amount G1 is approximately 0.5 (Nm 2 /min・ton)
It is.
【表】
以上のようにして、最小総ガス量G2は1.0N
m2／min・ton、最小炉口面積比σ１は５×10-3
m2／tonの条件で、精錬中連続的に炉口面積比σ
を変え、溶鋼中の窒素挙動を調べた。その結果を
実施例２で説明する。
実施例 ２
実施例１で得た結果に基づいて、第１表に化学
成分を示した高クロム鋼の精錬中に、炉口面積比
σを第３図に示すＡ域になるように、炉口の径が
異なる複数の炉蓋を連続的に取替えて調整した。
その間の溶鋼中の窒素濃度の挙動は第４図に示す
とおりである。この第４図より、この発明法によ
れば従来法に比較して窒素濃度は著しく低減され
ていることがわかる。
なお、上記実施例の炉口におけるガス流速は
2.2〜2.7ｍ／min（ガスは標準状態として）であ
り、ガス温度950℃で約11.2ｍ／minの値であ
る。
この発明は、上記のごとく、高クロム鋼精錬時
における溶鋼中の窒素濃度を低下させ得るばかり
でなく、窒素濃度の制御もできる。又上記は浴面
下にガス吹込みノズルを有する酸素上吹転炉に実
施した場合であるが、AOC炉などにも適用する
ことが可能である。[Table] As shown above, the minimum total gas amount G 2 is 1.0N
m 2 /min・ton, minimum furnace mouth area ratio σ 1 is 5×10 -3
Under the condition of m 2 /ton, the furnace mouth area ratio σ is continuously changed during refining.
The behavior of nitrogen in molten steel was investigated by changing the The results will be explained in Example 2. Example 2 Based on the results obtained in Example 1, during the refining of high chromium steel whose chemical composition is shown in Table 1, the furnace was adjusted so that the furnace mouth area ratio σ was in the A region shown in Figure 3. Adjustments were made by continuously replacing multiple furnace covers with different diameters.
The behavior of the nitrogen concentration in the molten steel during this period is as shown in FIG. From FIG. 4, it can be seen that according to the method of this invention, the nitrogen concentration is significantly reduced compared to the conventional method. In addition, the gas flow rate at the furnace mouth in the above example is
It is 2.2 to 2.7 m/min (assuming the gas is in a standard state), and the value is about 11.2 m/min at a gas temperature of 950°C. As described above, the present invention not only makes it possible to reduce the nitrogen concentration in molten steel during high chromium steel refining, but also makes it possible to control the nitrogen concentration. Furthermore, although the above example is applied to an oxygen top-blown converter furnace having a gas injection nozzle below the bath surface, it can also be applied to an AOC furnace or the like.
第１図は総ガス量Ｇと炉口面積比σとの関係に
おいて大気侵入防止域を示す図表、第２図は2.4
トン転炉で実施した場合の窒素挙動を示す図表、
第３図は第２図の結果に基づいて炉口面積比を調
整したときの操業パターンを従来法と比較して総
ガス量と炉口面積比との関係で示す図表、第４図
はこの発明法と従来法における溶鋼中の窒素濃度
の変化を示す図表である。
図中G1……最小総ガス、G2……最小総ガス
量、σ１……最小炉口面積比、σ２……最大炉口
面積比。
Figure 1 is a chart showing the atmospheric intrusion prevention zone in relation to the total gas amount G and the furnace mouth area ratio σ, and Figure 2 is a chart showing the area for preventing atmospheric intrusion.
A diagram showing the behavior of nitrogen when carried out in a ton converter,
Figure 3 is a chart showing the operation pattern when adjusting the furnace mouth area ratio based on the results in Figure 2, in comparison with the conventional method, in terms of the relationship between the total gas amount and the furnace mouth area ratio. It is a chart showing changes in nitrogen concentration in molten steel in the invention method and the conventional method. In the figure, G1 ...Minimum total gas, G2 ...Minimum total gas amount, σ1 ...Minimum furnace mouth area ratio, σ2 ...Maximum furnace mouth area ratio.
Claims (1)
き転炉により、浴面下へガスを吹込みながら上吹
き酸素を供給して鋼を精錬する際、炉内反応によ
る発生ガスとノズルより吹込むガスとの総ガス量
に応じて、大気の炉内侵入を防止し得る炉口排出
ガス流速となるよう下記により定義する炉口面積
比を変化させ、炉口から排出されるガス流速を確
保し、炉口周囲から炉内への大気侵入を防止する
ことを特徴とする高クロム鋼の製造法。 ただし、炉口面積比とは精錬炉の炉内から発生
するガスが通過するか、又は炉内へ大気が通過し
得る炉口面積の溶鋼１トン当りの値とする。 ２ 精錬の進行に応じて炉口面積比を減少させる
とともに、ノズルからのガス吹込み量を増加させ
ることを特徴とする特許請求の範囲第１項記載の
高クロム鋼の製造法。 ３ 炉口面積比がある一定値以下のとき、炉口周
囲にガスを噴射し炉口をガスシールすることを特
徴とする特許請求の範囲第１項又は第２項記載の
高クロム鋼の製造法。[Scope of Claims] 1. When refining steel by supplying top-blown oxygen while blowing gas below the bath surface using an oxygen top-blown converter having a gas injection nozzle below the bath surface, the furnace reaction Depending on the total gas amount of generated gas and gas blown in from the nozzle, the furnace mouth area ratio defined below is changed so that the flow rate of the furnace exhaust gas can prevent atmospheric air from entering the furnace, and the furnace is discharged from the furnace mouth. A manufacturing method for high chromium steel that is characterized by ensuring a gas flow rate of 100% and preventing air from entering the furnace from around the furnace mouth. However, the furnace mouth area ratio is defined as the value of the furnace mouth area per ton of molten steel through which the gas generated from the inside of the refining furnace can pass or the atmosphere can pass into the furnace. 2. The method for producing high chromium steel according to claim 1, which comprises decreasing the furnace mouth area ratio and increasing the amount of gas blown from the nozzle as the refining progresses. 3. Production of high chromium steel according to claim 1 or 2, characterized in that when the furnace mouth area ratio is below a certain value, gas is injected around the furnace mouth to gas-seal the furnace mouth. Law.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11477879A JPS5638412A (en) | 1979-09-06 | 1979-09-06 | Manufacture of high-chromium steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11477879A JPS5638412A (en) | 1979-09-06 | 1979-09-06 | Manufacture of high-chromium steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5638412A JPS5638412A (en) | 1981-04-13 |
| JPS6123844B2 true JPS6123844B2 (en) | 1986-06-07 |
Family
ID=14646440
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP11477879A Granted JPS5638412A (en) | 1979-09-06 | 1979-09-06 | Manufacture of high-chromium steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5638412A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20230019705A (en) * | 2021-08-02 | 2023-02-09 | 주식회사 엘지에너지솔루션 | Apparatus and method for managing battery |
| DE112020007490T5 (en) | 2020-08-04 | 2023-06-07 | Mitsubishi Electric Corporation | DEVICE FOR ESTIMATION OF THE INTERNAL CONDITION OF A STORAGE BATTERY AND METHOD OF ESTIMATION OF THE INTERNAL CONDITION OF A STORAGE BATTERY |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61159521A (en) * | 1984-12-30 | 1986-07-19 | Nippon Steel Corp | Low nitrogen steel blowing method |
| JP2615728B2 (en) * | 1987-12-26 | 1997-06-04 | 日本鋼管株式会社 | Decarburization method for Cr-containing pig iron |
-
1979
- 1979-09-06 JP JP11477879A patent/JPS5638412A/en active Granted
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE112020007490T5 (en) | 2020-08-04 | 2023-06-07 | Mitsubishi Electric Corporation | DEVICE FOR ESTIMATION OF THE INTERNAL CONDITION OF A STORAGE BATTERY AND METHOD OF ESTIMATION OF THE INTERNAL CONDITION OF A STORAGE BATTERY |
| KR20230019705A (en) * | 2021-08-02 | 2023-02-09 | 주식회사 엘지에너지솔루션 | Apparatus and method for managing battery |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5638412A (en) | 1981-04-13 |
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