JPS6232244B2 - - Google Patents
Info
- Publication number
- JPS6232244B2 JPS6232244B2 JP57198030A JP19803082A JPS6232244B2 JP S6232244 B2 JPS6232244 B2 JP S6232244B2 JP 57198030 A JP57198030 A JP 57198030A JP 19803082 A JP19803082 A JP 19803082A JP S6232244 B2 JPS6232244 B2 JP S6232244B2
- Authority
- JP
- Japan
- Prior art keywords
- gas
- stirring
- blowing
- present
- oxygen
- 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 38
- 238000003756 stirring Methods 0.000 claims description 26
- 238000007664 blowing Methods 0.000 claims description 25
- 238000000034 method Methods 0.000 claims description 20
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 14
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 9
- 239000001301 oxygen Substances 0.000 claims description 9
- 229910052760 oxygen Inorganic materials 0.000 claims description 9
- 238000007670 refining Methods 0.000 claims description 9
- 239000001569 carbon dioxide Substances 0.000 claims description 7
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 7
- 239000011261 inert gas Substances 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 3
- 239000000463 material Substances 0.000 claims description 2
- 230000010349 pulsation Effects 0.000 description 13
- 229910000831 Steel Inorganic materials 0.000 description 10
- 239000010959 steel Substances 0.000 description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 9
- 239000002893 slag Substances 0.000 description 8
- 230000000694 effects Effects 0.000 description 7
- 230000007423 decrease Effects 0.000 description 5
- 238000007796 conventional method Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 230000008094 contradictory effect Effects 0.000 description 1
- -1 etc. Chemical compound 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 229910052757 nitrogen Inorganic materials 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
- C21C5/30—Regulating or controlling the blowing
- C21C5/35—Blowing from above and through the bath
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
Description
本発明は上底吹転炉精錬方法に関し、その目的
はFeおよびMnの歩留りが良く、さらに脱Ｐ効率
の優れた精錬方法を提供することにある。
近時、歩留りおよび精錬反応効率の向上を目的
として上部ランスから酸素（O2）を下部から撹拌
ガスを吹込む上底吹転炉精錬方法が実施されるよ
うになつた。
一方、鉄鋼需要の面から低Ｐ鋼が望まれ始め、
この低Ｐ鋼を上底吹転炉で溶製する方法が研究さ
れ始めたが、〔Ｐ〕を下げようとすると〔Mn〕も
低くなり、逆に〔Mn〕を高めようとすると
〔Ｐ〕も高くなると云う二律背反の命題があり、
〔Ｐ〕を下げ〔Mn〕を高めると云う操業が可能な
方法は提案されていなかつた。
そこで、本発明者等は前記問題点の解決に努力
した結果、本発明を創出することによつて低Ｐで
高Mnの溶鋼を得ることを可能とした。
さて、上底吹転炉において、下部羽口または下
部ランスから吹込まれる撹拌ガス（窒素、アルゴ
ン等の不活性ガス、一酸化炭素や二酸化炭素、炭
化水素や酸素などのうち適宜なガスもしくは２種
以上の適宜に混合されたガス）の量を低めにして
溶鋼の弱撹拌を実施すると、スラグ中の鉄分
（Fe）が多くなつて歩留りが低下する傾向があ
り、逆に撹拌ガスの吹込みを多くして強撹拌する
とスラグ中のFeは減少し〔Ｐ〕も低下するもの
の〔Mn〕の歩留りが著しく低下する傾向が認め
られる。
従つて、従来の上底吹転炉精錬方法では、第１
図に示す通り、上部から酸素を、下部から撹拌ガ
スを吹込む（以下底吹とも云う）吹錬期間Ｗにお
いて、撹拌ガス量を吹錬初期では低目とし、吹錬
末期には多くして脱〔Ｐ〕を計ると共に〔Mn〕
の歩留りを良くする方法が採用されていた。
しかしながら、この従来法でも〔Ｐ〕、〔Mn〕
の両者について満足する結果を得ることが出来な
かつた。そこで、本発明者等は鋭意研究の結果、
第２図に示すように、吹錬期間Ｗの途中で底吹き
撹拌ガス流量を３回にわたり、間欠的に1.5倍量
以上多くする吹込み（図においてパルス状脈動
P1，P2，P3として示す）を実施（本発明法）した
ところ〔Ｐ〕が低く〔Mn〕が多い鋼を溶製する
ことが出来ることを確認した。
第１図の従来方法と第２図の本発明方法との溶
製結果の比較を次の第１表に示す。
The present invention relates to a top-bottom blowing converter refining method, and its purpose is to provide a refining method with good Fe and Mn yields and excellent P removal efficiency. Recently, for the purpose of improving yield and refining reaction efficiency, a top-bottom blown converter refining method has been implemented in which oxygen (O 2 ) is blown from the upper lance and stirring gas is blown from the lower part. On the other hand, from the perspective of steel demand, low P steel began to be desired.
Research has begun on a method of melting this low-P steel in a top-bottom blowing converter, but if you try to lower [P], [Mn] also decreases, and conversely, if you try to increase [Mn], [P] There is a contradictory proposition that the price will also increase.
No method has been proposed that allows operation to lower [P] and increase [Mn]. Therefore, the inventors of the present invention made efforts to solve the above-mentioned problems, and by creating the present invention, it became possible to obtain molten steel with low P and high Mn. Now, in an upper-bottom blowing converter, a stirring gas (inert gas such as nitrogen, argon, etc., carbon monoxide, carbon dioxide, hydrocarbon, oxygen, etc.) that is blown in from the lower tuyere or lower lance, or an appropriate gas or two. If molten steel is stirred weakly with a low amount of gas (mixed with more than 100% gas), the iron content (Fe) in the slag will increase and the yield will tend to decrease. When the amount of Fe in the slag is increased and the slag is vigorously stirred, Fe in the slag decreases and [P] also decreases, but there is a tendency for the yield of [Mn] to decrease significantly. Therefore, in the conventional top-bottom blowing converter refining method, the first
As shown in the figure, during the blowing period W in which oxygen is blown from the top and stirring gas is blown from the bottom (hereinafter also referred to as bottom blowing), the amount of stirring gas is set low at the beginning of the blowing, and increased at the end of the blowing. While planning to escape [P], [Mn]
A method was adopted to improve the yield. However, even with this conventional method, [P], [Mn]
It was not possible to obtain satisfactory results for both. Therefore, as a result of intensive research, the present inventors found that
As shown in Fig. 2, during the blowing period W, the bottom blowing stirring gas flow rate is intermittently increased by 1.5 times or more three times (in the figure, pulse-like pulsation occurs).
When P 1 , P 2 , and P 3 were carried out (the method of the present invention), it was confirmed that it was possible to produce steel with low [P] and high [Mn]. A comparison of the melting results between the conventional method shown in FIG. 1 and the method of the present invention shown in FIG. 2 is shown in Table 1 below.
【表】
試番１が従来方法で、試番２が本発明法である
が、本発明法の成績が優れていることが判る。
さて前記脈動P1，P2，P3は実際操業ではこのよ
うに判然としたパルス状にはならず、急峻なウエ
ーブ状となる。この点については後に詳述する。
次に本発明者等は転炉下部に羽口（＃１、
＃２）２本を適宜間隔をおいて設備し、第３図に
示した折線１で示す撹拌ガス流量を２分して、間
欠的吹込みの時期をずらせ羽口＃１、＃２からそ
れぞれ折線２，３で示すように吹込んだ、この溶
製の結果を第２表に示す。[Table] Trial No. 1 is the conventional method, trial No. 2 is the method of the present invention, and it can be seen that the results of the method of the present invention are excellent. Now, in actual operation, the pulsations P 1 , P 2 , and P 3 do not have such a distinct pulse shape, but instead have a steep wave shape. This point will be explained in detail later. Next, the inventors installed tuyeres (#1,
#2) Install two pipes at appropriate intervals, divide the stirring gas flow rate shown by broken line 1 in Figure 3 into two, and stagger the timing of intermittent blowing from tuyeres #1 and #2 respectively. Table 2 shows the results of this melting, which was blown as indicated by broken lines 2 and 3.
【表】
第２表から明らかな如く、この方法が〔Mn〕
の歩留りで特に良い成績が得られることが判る。
この理由は第４図ａ，ｂに示すように羽口
＃１、＃２からの撹拌ガス吹込量の変化により溶
鋼流４ａ，４ｂの方向が互に反転されるため撹拌
がムラのないものとなる結果と考えられる。尚、
図において５は溶鋼、６はスラグ、７は上吹酸素
ランスを示す。
この第４図ａ，ｂの方法では、前述の〔Ｐ〕、
〔Mn〕に対する効果にとどまらず、スロツピング
の発生が非常に少なく、またスラグのフオーミン
グも抑制できることが確認された。
さて本発明の撹拌ガス量の吹込みを間欠的に
1.5倍量以上変化させる点についてさらに詳述す
る。
第５図の脈動P8は撹拌ガス流量における変化を
模式的に示した概念図で、Ｈが脈動P8の持続時
間、Ｌが最大流量、ｌは定常流量を示す。定常流
量とは当該転炉においてスロツピングやフオーミ
ングなどで問題が生ずることなく精錬が良好に実
行できると考えられる最低限の流量で主として経
験によつて求められる流量である。
さて、実際の脈動はガス管路抵抗や弁の制御遅
れなどにより第６図のP9に示すような急峻なウエ
ーブとなる。この場合、持続時間ＨはウエブP9の
立上りから立下りまでで、最大流量Ｌは最高値を
とる。
而して本発明においては、前記脈動P9につい
て、Ｌ≧1.5l、Ｈ＞１分なる条件を満足させると
き良好な成績が得られた。
第７図はＬ≧1.5lの要件を説明する実施例であ
り、170ton転炉においてｌ＝300Nm3／Hrとし、
炭酸ガスを吹込み、Ｈを１分間として流量をＬ／
ｌを1.0〜3.5まで変化させた例である。第８図は
第７図の例において脱Ｐの指標であるlogK′pを
縦軸に、Ｌ／ｌを横軸にとつてlogK′pの変化を
示したグラフで、図から明らかなようにＬ／ｌが
1.5で良好となり、1.8以上で効果が飽和している
ことが判る。
logK′p＝Ｐ２Ｏ５／〔Ｐ〕２〔Ｔ・Ｆｅ）５
たゞしP2O5：転炉スラグ中のP2O5の濃度
（％）
〔Ｐ〕：溶鋼中のＰ濃度（％）
Ｔ・Fe：スラグ中に含有される鉄分濃
度（％）
第９図は第７図の例で、Ｈを0.1〜10分迄変化
させた場合のlogK′pを示す。図から１分以上で
良好な結果が得られ２分で効果が飽和し、それ以
上Ｈを大きくしてもあまり効果がないことが判
る。
次に脈動の回数であるが、第１０図に示す如
く、Ｈを一定として、1H×１回(a)、1/2Ｈ×２回
(b)、1/3Ｈ×３回(c)として実験した場合、第１１
図に示す通り、脈動回数の多いほど良い成績が得
られた。
しかしながら、実際操業では吹錬時間の制約が
あり、本発明者等は脈動回数３〜４回で充分な効
果が得られることを知つた。さらに本発明者等は
脈動の時期即ち撹拌ガス流量の間欠的変化の時期
はSi吹終期、副原料投入終期の２回に限定して実
施すれば、目的の80％以上を達成することができ
ると云う知見を得た。而して間欠的変化を３回行
う場合は吹錬期間のそれぞれ1/4、2/2、3/4経過
した時点を設定して実施すれば目的の85％以上の
効果が期待できる。又間欠的変化の間隔ｈはｈ＞
Ｈであることが望ましい。
次にＨ、Ｌ／ｌを種々に変化させた場合の効果
比較を第３表に示す。
第３表から明らかなように本発明の方法を用い
れば、〔Ｐ〕を下げ〔Mn〕の歩留りを向上させる
ことが出来る。
而して本発明に用いられる撹拌ガスとしては、
不活性ガス又は炭酸ガスあるいは両者の混合ガス
を用いて好適であつた。また吹錬条件によつては
不活性ガス又は炭酸ガスもしくはそれらの混合ガ
スのそれぞれに適宜量の酸素を添加することによ
り好成績が得られた。本発明の目的を逸脱しない
範囲において他の撹拌ガスや添加剤を適宜量添加
することも許容される。
以上詳細に説明した通り、本発明は上底吹転炉
において歩留りが良く高品質の鋼を精錬する実用
上極めて簡便でありながら効果の高い手段を提供
するものである。[Table] As is clear from Table 2, this method is suitable for [Mn]
It can be seen that particularly good results can be obtained in terms of yield. The reason for this is that as shown in Fig. 4a and b, the directions of the molten steel flows 4a and 4b are reversed by changing the amount of stirring gas blown from the tuyere #1 and #2, so that the stirring can be done evenly. This is considered to be the result. still,
In the figure, 5 indicates molten steel, 6 indicates slag, and 7 indicates a top-blown oxygen lance. In the method shown in FIG. 4 a and b, the above-mentioned [P],
In addition to the effect on [Mn], it was confirmed that the occurrence of slopping was extremely low and that slag forming could also be suppressed. Now, intermittently blow in the amount of stirring gas of the present invention.
The point of changing the amount by 1.5 times or more will be explained in more detail. The pulsation P 8 in FIG. 5 is a conceptual diagram schematically showing a change in the stirring gas flow rate, where H indicates the duration of the pulsation P 8 , L indicates the maximum flow rate, and l indicates the steady flow rate. The steady flow rate is the minimum flow rate at which refining can be performed satisfactorily without causing problems such as slopping or forming in the converter, and is determined mainly by experience. Now, the actual pulsation becomes a steep wave as shown at P9 in Fig. 6 due to gas line resistance, valve control delay, etc. In this case, the duration H is from the rise to the fall of the web P9 , and the maximum flow rate L takes the highest value. In the present invention, good results were obtained when the conditions L≧1.5l and H>1 minute were satisfied for the pulsation P9 . Figure 7 is an example explaining the requirement of L≧1.5l, where l=300Nm 3 /Hr in a 170ton converter,
Blow in carbon dioxide gas, set H for 1 minute, and set the flow rate to L/
This is an example in which l was varied from 1.0 to 3.5. Figure 8 is a graph showing the change in logK'p in the example of Figure 7, with logK'p, which is an index of de-P, taken on the vertical axis and L/l on the horizontal axis. L/l is
It can be seen that a value of 1.5 is good, and a value of 1.8 or higher indicates that the effect is saturated. logK′p=P 2 O 5 / [P] 2 [T・Fe) 5 addition P 2 O 5 : Concentration of P 2 O 5 in converter slag (%) [P]: P concentration in molten steel (%) T.Fe: Iron concentration contained in slag (%) FIG. 9 is an example of FIG. 7, and shows logK'p when H is varied from 0.1 to 10 minutes. From the figure, it can be seen that good results are obtained after 1 minute or more, the effect is saturated after 2 minutes, and increasing H beyond that point does not have much effect. Next, regarding the number of pulsations, as shown in Figure 10, assuming H is constant, 1H x 1 time (a), 1/2H x 2 times
(b), 1/3H x 3 times (c), the 11th
As shown in the figure, the higher the number of pulsations, the better the results were obtained. However, in actual operation, there is a restriction on the blowing time, and the present inventors have found that a sufficient effect can be obtained with 3 to 4 pulsations. Furthermore, the inventors of the present invention can achieve more than 80% of the objective by limiting the pulsation period, that is, the period of intermittent changes in the stirring gas flow rate, to two times: at the end of Si blowing and at the end of auxiliary material input. I got this knowledge. Therefore, if you perform intermittent changes three times, you can expect more than 85% of the desired effect if you set the time points after 1/4, 2/2, and 3/4 of the blowing period, respectively. Also, the interval h of intermittent change is h>
H is desirable. Next, Table 3 shows a comparison of effects when H and L/l are varied. As is clear from Table 3, by using the method of the present invention, it is possible to lower [P] and improve the yield of [Mn]. The stirring gas used in the present invention is as follows:
It was preferable to use inert gas, carbon dioxide gas, or a mixture of both gases. Further, depending on the blowing conditions, good results were obtained by adding an appropriate amount of oxygen to each of inert gas, carbon dioxide gas, or a mixture thereof. It is also permissible to add appropriate amounts of other stirring gases and additives within the scope of the purpose of the present invention. As explained in detail above, the present invention provides a practically extremely simple yet highly effective means for refining high-quality steel with a good yield in a top-bottom blowing converter.
第１図は従来の吹錬における底吹撹拌ガス流量
の変化を示すグラフ、第２図は本発明にかゝる底
吹撹拌ガス流量の変化を示すグラフ、第３図は本
発明の実施例にかゝる異つた底吹撹拌ガス流量の
変化を示すグラフ、第４図ａ，ｂは本発明にかか
る転炉溶鋼の撹拌状況を説明する概略図、第５
図、第６図は本発明にかゝる撹拌ガスの間欠的変
化を脈動として示す模式図、第７図は本発明にか
かる実施例での撹拌ガスの間欠的変化の説明図、
第８図、第９図は脱Ｐの効率を説明するための
夫々流量と吹込時間との相関グラフ、第１０図は
本発明にかかる撹拌ガスの間欠的吹込の態様を示
すグラフ、第１１図は前記態様毎の脱Ｐ率の比較
を示すグラフである。
P1〜P9：脈動、Ｈ：脈動持続時間、Ｌ：最大流
量、ｌ：定常流量。
Fig. 1 is a graph showing changes in the flow rate of bottom-blown stirring gas in conventional blowing, Fig. 2 is a graph showing changes in the flow rate of bottom-blowing stirring gas according to the present invention, and Fig. 3 is a graph showing an example of the present invention. Figures 4a and 4b are graphs showing changes in the flow rates of different bottom-blown stirring gases;
6 is a schematic diagram showing intermittent changes in the stirring gas according to the present invention as pulsations, and FIG. 7 is an explanatory diagram of the intermittent changes in the stirring gas in the embodiment according to the present invention.
Figures 8 and 9 are correlation graphs between flow rate and blowing time to explain the efficiency of P removal, Figure 10 is a graph showing the mode of intermittent blowing of stirring gas according to the present invention, and Figure 11 is a graph showing the intermittent blowing of stirring gas according to the present invention. is a graph showing a comparison of dephosphorization rates for each of the above embodiments. P1 to P9 : Pulsation, H: Pulsation duration, L: Maximum flow rate, l: Steady flow rate.
Claims (1)
上底吹転炉精錬方法において、前記撹拌ガス流量
を吹錬の初期から末期にかけて１回もしくは２回
以上間欠的に1.5倍量以上変化させることを特徴
とする上底吹転炉精錬方法。 ２ 撹拌ガスが不活性ガスもしくは不活性ガスに
酸素を添加したものである特許請求の範囲第１項
記載の方法。 ３ 撹拌ガスが炭酸ガスもしくは炭酸ガスに酸素
を添加したものである特許請求の範囲第１項記載
の方法。 ４ 撹拌ガスが不活性ガスと炭酸ガスの混合ガス
もしくはそれに酸素を添加したものである特許請
求の範囲第１項記載の方法。 ５ 撹拌ガスの間欠的変化をSi吹終期および副原
料投入終期に限定実施する特許請求の範囲第１項
乃至第４項の何れかに記載の方法。[Claims] 1. In a top-bottom blowing converter refining method in which oxygen is blown from the upper part and stirring gas is blown from the lower part, the stirring gas flow rate is intermittently increased to 1.5 times or more once or twice from the beginning to the end of blowing. A top-bottom blowing converter refining method characterized by changing the amount by more than double. 2. The method according to claim 1, wherein the stirring gas is an inert gas or an inert gas to which oxygen is added. 3. The method according to claim 1, wherein the stirring gas is carbon dioxide gas or carbon dioxide gas to which oxygen is added. 4. The method according to claim 1, wherein the stirring gas is a mixed gas of an inert gas and carbon dioxide gas, or a gas mixture to which oxygen is added. 5. The method according to any one of claims 1 to 4, in which intermittent changes in the stirring gas are limited to the final stage of Si blowing and the final stage of inputting auxiliary materials.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19803082A JPS5989705A (en) | 1982-11-11 | 1982-11-11 | Refining method with top and bottom blown converter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19803082A JPS5989705A (en) | 1982-11-11 | 1982-11-11 | Refining method with top and bottom blown converter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5989705A JPS5989705A (en) | 1984-05-24 |
| JPS6232244B2 true JPS6232244B2 (en) | 1987-07-14 |
Family
ID=16384353
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP19803082A Granted JPS5989705A (en) | 1982-11-11 | 1982-11-11 | Refining method with top and bottom blown converter |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5989705A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009293096A (en) * | 2008-06-06 | 2009-12-17 | Kobe Steel Ltd | Method for injecting bottom-blowing agitation gas in melting furnace |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS55158208A (en) * | 1979-05-24 | 1980-12-09 | Sumitomo Metal Ind Ltd | Refining method of steel |
-
1982
- 1982-11-11 JP JP19803082A patent/JPS5989705A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS55158208A (en) * | 1979-05-24 | 1980-12-09 | Sumitomo Metal Ind Ltd | Refining method of steel |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5989705A (en) | 1984-05-24 |
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