JPH0791616B2 - Melting method of stainless steel using semi-reduced chromium pellets - Google Patents
Melting method of stainless steel using semi-reduced chromium pelletsInfo
- Publication number
- JPH0791616B2 JPH0791616B2 JP62113681A JP11368187A JPH0791616B2 JP H0791616 B2 JPH0791616 B2 JP H0791616B2 JP 62113681 A JP62113681 A JP 62113681A JP 11368187 A JP11368187 A JP 11368187A JP H0791616 B2 JPH0791616 B2 JP H0791616B2
- Authority
- JP
- Japan
- Prior art keywords
- semi
- reduced chromium
- pellets
- slag
- reduced
- 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
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- Manufacture Of Iron (AREA)
- Treatment Of Steel In Its Molten State (AREA)
- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
- Manufacture And Refinement Of Metals (AREA)
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は，クロム源として半還元クロムペレットを用い
た電気炉法によるステンレス鋼（ステンレス鋼の粗溶
鋼）の溶製方法に関する。The present invention relates to a method for producing stainless steel (crude molten steel of stainless steel) by an electric furnace method using semi-reduced chromium pellets as a chromium source.
従来，ステンレス鋼を製造するには，クロム鉱石をいっ
たん固相還元炉で予備還元して半還元クロムペレットを
製造し、この半還元クロムペレットをフェロアロイ用電
気炉（例えば,ELKEM炉）で還元して炭素飽和の高炭素フ
ェロクロムを製造し，これを他の製鋼原料とともに製鋼
炉で再度溶解，脱炭して製造されるのが最も通常の方法
である。Conventionally, to produce stainless steel, chromium ore is once pre-reduced in a solid-state reduction furnace to produce semi-reduced chromium pellets, which are then reduced in a ferroalloy electric furnace (eg, ELKEM furnace). The most common method is to produce carbon-saturated high-carbon ferrochrome, which is then melted and decarburized again in a steelmaking furnace together with other steelmaking raw materials.
したがって，この製造方法では，クロム酸化物の還元に
要する多量のエネルギーとして高価な電力を用い，しか
も，溶融物として製造された高炭素フェロクロムをいっ
たん凝固し，固型原料として製鋼炉内で再度溶解される
ため，エネルギー損失が大きいという問題がある。Therefore, in this manufacturing method, expensive electric power is used as a large amount of energy required for the reduction of chromium oxide, and the high carbon ferrochrome produced as a melt is once solidified and then melted again in the steelmaking furnace as a solid raw material. Therefore, there is a problem that the energy loss is large.
そこで，高炭素フェロクロムの製造工程を省き，予備還
元された半還元クロムペレットを製鋼用電気炉に直接に
装入すれば，工程が簡潔となりエネルギー損失が小さく
なるという考えが，例えば特開昭55−79817号公報に開
示されている。Therefore, an idea that if the pre-reduced semi-reduced chromium pellets are directly charged into an electric furnace for steelmaking by omitting the high carbon ferrochrome production process, the process is simplified and energy loss is reduced. -79817.
電気炉に半還元クロムペレットを直接装入する場合に
は，次のような問題が付随する。When the semi-reduced chromium pellets are directly charged into the electric furnace, the following problems are involved.
（ａ）．半還元クロムペレットは溶融物に対し濡れ性が
悪く，また，電気伝導性が低いため，電気炉内に多量の
半還元クロムペレットを装入すると未溶解および通電不
足の原因となる。(A). Since semi-reduced chromium pellets have poor wettability with respect to the melt and have low electric conductivity, charging a large amount of semi-reduced chromium pellets into the electric furnace causes unmelting and insufficient current flow.
（ｂ）．十分な還元を行うためには，溶銑の炭素濃度を
飽和状態まで高める必要がある。このため脱炭精錬の負
荷を増大させる。(B). In order to achieve sufficient reduction, it is necessary to raise the carbon concentration of the hot metal to a saturated state. Therefore, the load of decarburization and refining is increased.
（ｃ）．半還元クロムペレットの還元には多くの還元エ
ネルギーを必要とするため，多量に半還元クロムペレッ
トを使用すると，溶解時間が増大する。(C). Since a large amount of reduction energy is required to reduce the semi-reduced chromium pellets, if a large amount of semi-reduced chromium pellets is used, the dissolution time will increase.
（ｄ）．半還元クロムペレットは嵩比量が小さいので多
量に装入する場合，炉容の拡大または装入回数の増が必
要となる。(D). Since the bulk ratio of semi-reduced chromium pellets is small, it is necessary to expand the furnace volume or increase the number of times of charging when charging a large amount.
前記の特開昭55−79817号公報では、電気炉内の中央部
に空間が形成されるように先ず鋼屑を炉底や炉周壁に敷
き詰めたうえ，この中央部の空間に半還元クロムペレッ
ト，コークスおよび石灰を装入してから通電を開始して
溶解するという固形材料の炉内への敷き詰め方を改善す
ることによって前記のような問題を解決しようとしたも
のであるが，溶解性や通電性になお解決されるべき問題
が残されている。In the above-mentioned JP-A-55-79817, steel scrap is first spread over the furnace bottom and the peripheral wall of the electric furnace so that a space is formed in the center of the electric furnace. In order to solve the above-mentioned problems by improving the method of laying solid material in the furnace, in which the electric current is started to melt after the coke and lime are charged, the solubility and There are still problems to be solved in terms of conductivity.
本発明は，かような半還元クロムペレットの一括装入と
いう方法では溶解性や還元性に問題があり，多量の半還
元クロムペレットを使用するには限界があることに鑑
み，これに代わる半還元クロムペレットの電気炉での溶
解・還元を有利に促進する方法の提供を目的としたもの
である。The present invention is an alternative to the semi-reduced chromium pellets in view of the fact that the method of batch-charging the semi-reduced chromium pellets has a problem in solubility and reducibility, and there is a limit in using a large amount of the semi-reduced chromium pellets. The purpose of the present invention is to provide a method for advantageously promoting dissolution / reduction of reduced chromium pellets in an electric furnace.
本発明は，半還元クロムペレットをクロム源の一部また
は全部に使用して電気炉によりステンレス鋼（例えばＣ
レベルが１〜３％程度の粗溶鋼）を溶製するさいに，先
ず該電気炉にスクラップおよび造滓材からなる製鋼原料
を装入してこれらを実質上溶解し，次いで前記の半還元
クロムペレットを該電気炉内の電極近傍のスラグ層に少
量づつ回分式にまたは連続式に装入すると共に還元材を
該スラグ層に装入することを特徴とする。The present invention uses semi-reduced chromium pellets for some or all of the chromium source to produce stainless steel (eg C
When melting (crude molten steel having a level of about 1 to 3%), first, a steelmaking raw material consisting of scrap and slag material is charged into the electric furnace to substantially melt them, and then the semi-reduced chromium The pellets are charged into the slag layer in the vicinity of the electrode in the electric furnace little by little in a batch or continuous manner, and a reducing agent is charged into the slag layer.
本発明者らは，上記した本発明の目的を達成すべく長年
の研究と実験を重ねてきたが，電気炉により半還元クロ
ムペレットを効率よく溶融還元するためには，次のこと
が重要であることを見出して本発明をなすに至ったもの
である。The present inventors have conducted many years of research and experiments to achieve the above-mentioned object of the present invention, but in order to efficiently smelt and reduce semi-reduced chromium pellets by an electric furnace, the following is important. The present invention has been made by finding out that there is such a thing.
（１）半還元クロムペレットの還元場所は，還元が吸熱
反応であるため，高温かつ滓化の容易な電気炉内の電極
下端近傍のスラグ層内が適している。(1) Since the reduction is an endothermic reaction, the suitable place for the reduction of the semi-reduced chromium pellets is in the slag layer near the lower end of the electrode in the electric furnace where the temperature is high and slag formation is easy.
（２）嵩比重の小さい半還元クロムペレットを多量に装
入するには，一括投入ではなく少量づつを回分式または
連続的に装入する方式が適している。(2) In order to charge a large amount of semi-reduced chromium pellets having a low bulk specific gravity, a batch type or continuous charging method is suitable, instead of batch charging.
（３）半還元クロムペレットが団塊状となり炉壁および
炉床に未溶解付着物として残留することを防ぐには，電
気炉内に半還元クロムペレットを一度に装入せず，少量
づつ装入するのが好ましい。(3) In order to prevent the semi-reduced chromium pellets from becoming a nodule and remaining on the furnace wall and hearth as undissolved deposits, do not load the semi-reduced chromium pellets into the electric furnace at once, but in small amounts. Preferably.
（４）通電不良を防止するには，電気炉内に半還元クロ
ムペレットの層やかたまりを作らないようにする必要が
ある。(4) In order to prevent defective conduction, it is necessary not to form a layer or lump of semi-reduced chromium pellets in the electric furnace.
（５）脱炭精錬の負荷を減じるためには，炭材をスラグ
層内に浮遊させ，スラグ−炭材間にて還元反応を進行さ
せることが有利である。これによって溶銑〔％Ｃ〕を高
める必要がなくなり，脱炭負荷を軽減できる。(5) In order to reduce the load of decarburization refining, it is advantageous to suspend the carbonaceous material in the slag layer and allow the reduction reaction to proceed between the slag and the carbonaceous material. This eliminates the need to increase the hot metal [% C] and reduces the decarburization load.
本発明はこのような知見を具現化する方法として，電気
炉に半還元クロムペレットほかの連続装入設備（送原設
備）を設け，この送原設備から炉内溶融物における通電
中の電極下端近傍（スラグ層内）に半還元クロムペレッ
トを少量づつ回分式または連続式に装入するものであ
る。すなわち，まず鋼屑や造滓材などの製鋼原料を実質
上溶解し造滓した後，半還元クロムペレットを電気炉内
の電極下端近傍のスラグ層内に所要の時間をかけながら
その全装入量を少量づつ回分して装入するか連続流れに
して所要の時間をかけて少しづつに装入してその全量の
溶解・還元を経時的に進行させることに特徴がある。そ
のさい，半還元クロムペレットと共に還元材としての炭
材及び造滓材もスラグ層内に必要量を少量づつ装入する
ことができる。この場合には半還元クロムペレットの還
元反応を一層有利に進行させることができる。また，本
発明法で使用する半還元クロムペレットとしては，固相
還元炉にて予備還元した高温状態（例えば1000〜1200℃
の高温状態）のままの半還元クロムホットペレットをそ
の熱を実質上保有したままの状態で用いることができ，
これによって半還元クロムペレットの溶解と還元反応を
さらに有利に進行させることができる。この場合に半還
元クロムペレットの装入設備は耐火性の内張りを施した
ものを使用するのがよい。As a method of embodying such knowledge, the present invention provides an electric furnace with a continuous charging facility (source facility) such as semi-reduced chromium pellets, and from this source facility, the lower end of the electrode in the furnace melt during energization. Semi-reduced chromium pellets are charged little by little in the vicinity (within the slag layer) in a batch or continuous manner. That is, first, steelmaking raw materials such as steel scraps and slag materials are substantially melted and smelted, and then the semi-reduced chromium pellets are fully charged into the slag layer near the lower end of the electrode in the electric furnace over the required time. It is characterized in that the amount is charged in small batches or in a continuous flow in small amounts over the required time to allow the total amount of dissolution / reduction to proceed with time. At that time, the carbonaceous material and the slag material as the reducing material can be charged into the slag layer in a small amount together with the semi-reduced chromium pellets. In this case, the reduction reaction of the semi-reduced chromium pellets can proceed more advantageously. Further, the semi-reduced chromium pellets used in the method of the present invention include a high-temperature state (for example, 1000 to 1200 ° C.) preliminarily reduced in a solid-phase reduction furnace.
It is possible to use the semi-reduced chromium hot pellets as they are (high temperature state of
This allows the dissolution and reduction reaction of the semi-reduced chromium pellets to proceed more advantageously. In this case, it is preferable that the charging equipment for the semi-reduced chromium pellets has a refractory lining.
第１図は，本発明の方法を実施するのに用いる装置例を
示したものである。図示のように，電気炉としては，複
数の電極１をもつエルー式のアーク炉２が用いられ，こ
のアーク炉２の炉蓋３を貫通したシュート４が設置され
ている。このシュート４からの物質投入口となる炉内の
装入開口端５は複数の電極１の間（炉の中央部）に位置
しており，シュート４から物質を炉内に投入すれば，電
極１の近傍に落下するようにしてある。シュート４の上
部には送原設備であるバンカー6,7,8が接続されてい
る。図示の例ではバンカー６には半還元クロムペレット
９が，バンカー７にはコークス10が，そしてバンカー８
には造滓材11が装入されており，これらバンカー内の各
材料をそれらの投入量を調整しながらシュート４に送り
込めるようになっている。既述のように高温のままの半
還元クロムホットペレットを使用する場合には，バンカ
ー６を耐火物で内張りしておく。FIG. 1 shows an example of an apparatus used to carry out the method of the present invention. As shown in the figure, as an electric furnace, an Eru type arc furnace 2 having a plurality of electrodes 1 is used, and a chute 4 penetrating a furnace lid 3 of the arc furnace 2 is installed. The charging opening end 5 in the furnace, which serves as a material charging port from the chute 4, is located between the plurality of electrodes 1 (central part of the furnace). It is designed to fall near 1. Bunkers 6, 7 and 8 as a source equipment are connected to the upper part of the chute 4. In the illustrated example, the bunker 6 is provided with semi-reduced chromium pellets 9, the bunker 7 is provided with coke 10, and the bunker 8 is provided.
A slag material 11 is loaded into the bunker so that each material in the bunker can be sent to the chute 4 while adjusting the input amount thereof. As described above, when using the semi-reduced chromium hot pellets at high temperature, the bunker 6 is lined with a refractory material.
操業にあたっては，まず，前段階として鋼屑，造滓材を
中心とした製鋼原料を通常のバスケット（図示していな
い）によりアーク炉２内に装入して通電を開始して溶解
する。次いで，アーク炉２内に溶銑12及びスラグ層13が
実質上生成したならば，バンカー６内の半還元クロムペ
レット９をシュート４を経て装入開口端５から電極近傍
のスラグ層13に少量づつ回分式または連続式に装入す
る。電極近傍の溶融スラグ層13に落下した半還元クロム
ペレットは直ちに電極下端のアーク放電位置に自然に移
動して溶解・還元が直ちに進行する。In operation, first, as a pre-stage, steel scraps and slag-making steel-making raw materials are charged into the arc furnace 2 by an ordinary basket (not shown), and current is started to be melted. Next, when the hot metal 12 and the slag layer 13 are substantially generated in the arc furnace 2, the semi-reduced chromium pellets 9 in the bunker 6 are gradually passed through the chute 4 from the charging opening end 5 to the slag layer 13 near the electrode. Charge in batch or continuous mode. The semi-reduced chromium pellets that have fallen into the molten slag layer 13 near the electrode immediately move spontaneously to the arc discharge position at the lower end of the electrode and the dissolution / reduction proceeds immediately.
また，この半還元クロムペレットの連続装入と共に，必
要に応じて，バンカー７のコークス10および／またバン
カー８の造滓材11（例えば石灰）を同じシュート４を通
じて装入する。これにより半還元クロムペレットは電極
下端近傍で高温状態にあるスラグ層13内において速やか
に溶解，還元および滓化が進行する。Further, along with the continuous charging of the semi-reduced chromium pellets, the coke 10 of the bunker 7 and / or the slag material 11 (for example, lime) of the bunker 8 are charged through the same chute 4, if necessary. As a result, the semi-reduced chromium pellets are rapidly dissolved, reduced, and slagified in the slag layer 13 in the high temperature state near the lower end of the electrode.
本発明法においては，半還元クロムペレット９の還元反
応はスラグ層13に浮遊する炭材表面にて実質上進行す
る。したがって，溶銑12に溶解している炭素を還元に利
用することは殆どなく，このため溶銑12の炭素濃度を飽
和状態まで高めておく必要はとくにない。また，本発明
では半還元クロムペレット，コークス，造滓材のシュー
ト４を通じての装入速度（単位時間当りの投入量）を適
宜調整することができるので，例えばこれらが溶解して
いることが支配的であるような溶解律速の時点ではその
装入速度を遅くする等の調整ができ，これによって，半
還元クロムペレットが団塊状未溶解物となることを防止
でき，ひいては溶解不良及び通電不良を防止できる。In the method of the present invention, the reduction reaction of the semi-reduced chromium pellets 9 substantially proceeds on the surface of the carbonaceous material floating in the slag layer 13. Therefore, the carbon dissolved in the hot metal 12 is rarely used for the reduction, and therefore it is not particularly necessary to raise the carbon concentration of the hot metal 12 to the saturated state. Further, in the present invention, the charging speed (charge per unit time) of the semi-reduced chromium pellets, coke, and slag material through the chute 4 can be adjusted as appropriate, so that, for example, it is determined that they are dissolved. It is possible to adjust the charging rate to be slow at the time of the melting rate control, which is the target, and to prevent the semi-reduced chromium pellets from becoming a nodular undissolved material. It can be prevented.
一般にクロム酸化物の還元完了までの反応速度を比較す
ると，還元反応よりも溶解反応が律速である。したがっ
て，半還元クロムペレットを効率良く還元するには速や
かに溶解する必要がある。本発明においては，半還元ク
ロムペレットの溶解場所として，電気炉内で最も高温か
つアークフレームによる撹拌効果の期待できる電極下端
近傍を利用し，且つその投入を少量づつ行うので効果的
な溶解が行われる。Generally, when the reaction rates until the reduction of chromium oxide is completed are compared, the dissolution reaction is more rate limiting than the reduction reaction. Therefore, in order to efficiently reduce the semi-reduced chromium pellets, it is necessary to dissolve them quickly. In the present invention, the semi-reduced chromium pellets are melted at the highest temperature in the electric furnace near the lower end of the electrode where the stirring effect can be expected by the arc flame, and the charging is performed little by little, so that the effective melting is performed. Be seen.
また，クロム酸化物の還元反応は吸熱反応である。この
場合，溶解したスラグ中の酸化クロムがその近傍に存在
する炭素（固体状態にあるコークス粉）によって還元さ
れる次式で表される反応が本発明では支配的となる。The reduction reaction of chromium oxide is an endothermic reaction. In this case, the reaction represented by the following formula, in which the chromium oxide in the dissolved slag is reduced by the carbon (coke powder in the solid state) existing in the vicinity thereof, is dominant in the present invention.
（Cr2O3）＋Ｃ→（Cr7C3またはCr24C7）＋CO この反応は吸熱反応であるから，還元場所としては高温
である程好ましく，本発明では常に高温が維持されてい
る場所でこの反応が起こり、したがって還元反応も有利
に進行することができる。なお，スラグ中の酸化クロム
が溶銑中の固溶炭素と反応して次式に従う還元反応がス
ラグと溶銑の界面でも生じることが考えられる。(Cr 2 O 3 ) + C → (Cr 7 C 3 or Cr 24 C 7 ) + CO Since this reaction is an endothermic reaction, a higher temperature is preferable as the reduction site, and in the present invention, a high temperature is always maintained. This reaction takes place, and therefore the reduction reaction can also proceed advantageously. It is considered that the chromium oxide in the slag reacts with the solid solution carbon in the hot metal and a reduction reaction according to the following equation also occurs at the interface between the slag and the hot metal.
（Cr2O3）＋３〔Ｃ〕→２〔Cr〕＋3CO しかし，このスラグー溶銑の界面反応は本発明では支配
的とはならないので，溶銑の炭素濃度を飽和状態まで高
めておく必要はない。(Cr 2 O 3 ) +3 [C] → 2 [Cr] + 3CO However, since the interfacial reaction of this slag-hot metal is not dominant in the present invention, it is not necessary to raise the carbon concentration of the hot metal to a saturated state.
以上のようにして本発明によると，電気炉内の最も高温
状態となる電極下端近傍のスラグ層内を半還元クロムペ
レットの溶解及び還元場所として利用し，かつこの場所
に半還元クロムペレットを少量づつ回分式または連続式
に装入するようにしたので，従来の一括装入とは異なっ
て半還元クロムペレットの還元が効率よく行われると共
に作業性もよくなり，炭材や造滓材も随時この場所に装
入することによって一層有利に溶解・還元を進行させる
ことができる。また，表面状態がポーラスであって濡れ
性が悪い半還元クロムペレット（固相還元した半還元ク
ロムペレットは通常のような性質を有する）であって
も，回分式または連続式に投入するさいの装入速度の調
整によって団塊状となるのが防止され，その溶解を効果
的に進行させることができる等の優れた効果を発揮する
ものである。As described above, according to the present invention, the inside of the slag layer in the vicinity of the lower end of the electrode in the electric furnace where the temperature is the highest is used as a place for melting and reducing the semi-reduced chromium pellets, and a small amount of the semi-reduced chromium pellets is placed in this place. Since batch charging or continuous charging is performed one by one, unlike the conventional batch charging, the reduction of semi-reduced chromium pellets is efficiently performed and workability is improved, and carbonaceous materials and slag materials are also used at any time. By charging in this place, the dissolution / reduction can be proceeded more advantageously. In addition, even if the semi-reduced chromium pellets whose surface is porous and have poor wettability (solid-reduced semi-reduced chromium pellets have the usual properties), do not charge them in a batch or continuous manner. By adjusting the charging speed, it is possible to prevent the formation of nodule, and to exert an excellent effect such that the dissolution can be effectively promoted.
そして炭材及び造滓材の種類，装入量を適当に選択する
ことにより，還元の促進，溶解及び滓化の促進，スラグ
組成のコントロール等が可能である。例えば，蛍石等ハ
ロゲン化物を装入すれば溶解及び滓化が促進し、半還元
クロムペレットの含有するSiO2を補償する量のCaOを連
続に装入することによりスラグ塩基度を一定に保つこと
ができる。したがって，本発明の方法によると半還元ク
ロムペレットを用いて効率的にかつ経済的にステンレス
鋼を溶製可能であり，そのクロム収率も後記の実施例で
示すように高くなる。By appropriately selecting the type and charging amount of the carbonaceous material and slag material, it is possible to accelerate the reduction, accelerate the dissolution and slag formation, and control the slag composition. For example, when a halide such as fluorite is charged, dissolution and slag formation are promoted, and the slag basicity is kept constant by continuously charging an amount of CaO that compensates for SiO 2 contained in the semi-reduced chromium pellets. be able to. Therefore, according to the method of the present invention, it is possible to melt stainless steel efficiently and economically using the semi-reduced chromium pellets, and the chromium yield is also high as shown in the examples described later.
以下，本発明の具体的操業例を挙げて比較例とその効果
を具体的に対比する。Hereinafter, the specific operation example of the present invention will be given to specifically compare the comparative example with its effect.
操業は，第１図に示したような能力40トンのエルー式ア
ーク炉を用いて行ったものである。また使用した半還元
クロムペレットは第１表に示す化学組成を有するもので
ある。The operation was performed using an Eru arc furnace with a capacity of 40 tons as shown in Fig. 1. The semi-reduced chromium pellets used had the chemical composition shown in Table 1.
〔比較例１〕 溶製対象鋼種は18％Cr鋼とし，電気炉に普通鋼屑27300k
g,半還元クロムペレット24000kg,コークス2300kg,CaO 2
530kg,FeSi 130kgを装入したうえ，通常操業にて溶製し
た。ただし半還元クロムペレットは嵩比重が小さく原料
容積大なるため，各原料を３等分して３回にわけて一括
装入した。[Comparative Example 1] The steel type to be melted is 18% Cr steel and ordinary steel scrap 27300k in the electric furnace.
g, semi-reduced chromium pellets 24000kg, coke 2300kg, CaO 2
530 kg and FeSi 130 kg were charged and melted in normal operation. However, since the semi-reduced chromium pellets have a small bulk specific gravity and a large raw material volume, each raw material was divided into three equal parts and charged in batches in three times.
溶製結果を第２表に示した。溶銑重量は40.1トンであ
り，スラグ重量は10.5トンであった。この時のクロム収
率は93.2％であった。The melting results are shown in Table 2. The weight of hot metal was 40.1 tons and the weight of slag was 10.5 tons. The chromium yield at this time was 93.2%.
溶製時，非常に溶解性が悪く，特に炉壁近傍には半還元
クロムペレットが団塊状の未溶解物として付着した。ま
た，各装入後の送電開始時には，通電不良となり電極直
下に普通鋼屑を敷く必要があった。During melting, the solubility was extremely poor, and semi-reduced chromium pellets adhered as nodule-like undissolved material, especially near the furnace wall. Moreover, when power transmission was started after each charging, there was a failure in energization, and ordinary steel scrap had to be laid directly under the electrodes.
〔実施例１〕 溶製対象鋼種は18％Cr鋼とし，電気炉に普通鋼屑27500k
g,CaO 1020kg,FeSi 130kg,ケイ砂980kgをバスケットに
より装入し，溶解し造滓した。次いで，溶銑及びスラグ
が形成した後，第１図に示したようにバンカー及びシュ
ートを用いて，電極下端近傍のスラグ層内に半還元クロ
ムペレット24100kg,コークス2200kg,CaO2500kgを連続的
に装入した。装入速度は500kg/分とした。[Example 1] The steel type to be melted was 18% Cr steel and ordinary steel scrap 27500k was put in the electric furnace.
g, CaO 1020 kg, FeSi 130 kg, and silica sand 980 kg were charged in a basket, melted, and slag was produced. Then, after the hot metal and slag were formed, 24100 kg of semi-reduced chromium pellets, 2200 kg of coke, and 2500 kg of CaO were continuously charged into the slag layer near the lower end of the electrode using a bunker and chute as shown in Fig. 1. . The charging rate was 500 kg / min.
溶製結果を第３表に示した。溶銑重量は40.8トン，スラ
グ重量は12.1トンであった。この時のクロム収率は97.6
％であった。溶製時に未溶解及び通電不良は発生しなか
った。The melting results are shown in Table 3. The weight of hot metal was 40.8 tons and the weight of slag was 12.1 tons. The chromium yield at this time was 97.6.
%Met. At the time of melting, neither unmelting nor defective conduction occurred.
上記の比較例１及び実施例１を同じ条件にて各々５チャ
ージ溶製した結果を第４表に示した。Table 4 shows the results of melting 5 charges of each of the above Comparative Example 1 and Example 1 under the same conditions.
これらの結果に見られるように，本発明法によると，従
来法による比較例に比較して，クロム収率は，約４％向
上した。As can be seen from these results, according to the method of the present invention, the chromium yield was improved by about 4% as compared with the comparative example by the conventional method.
〔実施例２〕 半還元クロムホットペレットの溶解電力への効果を把握
するために，半還元クロムペレットと半還元クロムホッ
トペレットの比率を種々変えた以外は前記実施例１と同
様の操業条件で18％Cr鋼を溶製し，溶解電力の消費傾向
を調査した。その結果を第２図に示した。第２図は，半
還元クロムホットペレット比率と溶解電力消費指数の関
係で表示したものである。溶解電力消費指数は，実施例
１に示した５チャージの溶解電力原単位の平均値を100
とした。第２図より，全量を半還元クロムホットペレッ
トとすることにより，溶解電力が約25％低減できる効果
が認められる。 [Example 2] In order to understand the effect of the semi-reduced chromium hot pellets on the melting power, the same operating conditions as in Example 1 were used except that the ratio of the semi-reduced chromium pellets and the semi-reduced chromium hot pellets was changed variously. 18% Cr steel was melted and the consumption power consumption tendency was investigated. The results are shown in FIG. Fig. 2 shows the relationship between the semi-reduced chromium hot pellet ratio and the melting power consumption index. The dissolution power consumption index is 100, which is the average value of the dissolution power consumption per unit of 5 charges shown in Example 1.
And From Fig. 2, it is confirmed that the melting power can be reduced by about 25% by using the whole amount of the semi-reduced chromium hot pellets.
【図面の簡単な説明】 第１図は，本発明法を実施する装置の一例を示した略断
面図，第２図は本発明の実施例２の結果を示す半還元ク
ロムホットペレット比率と溶解電力消費指数の関係を示
す図である。 １……電極、２……アーク式電気炉,3……炉蓋,4……シ
ュート,5……装入開口端,6……バンカー（半還元クロム
ペレット用）,7……バンカー（炭材用）,8……バンカー
（造滓材用）。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view showing an example of an apparatus for carrying out the method of the present invention, and FIG. 2 shows the results of Example 2 of the present invention. It is a figure which shows the relationship of a power consumption index. 1 ... Electrode, 2 ... Arc type electric furnace, 3 ... Furnace lid, 4 ... Chute, 5 ... Charging opening end, 6 ... Bunker (for semi-reduced chromium pellets), 7 ... Bunker (charcoal 8) Bunker (for slag material).
Claims (3)
たは全部に使用して電気炉によりステンレス鋼を溶製す
るさいに，先ず該電気炉にスクラップおよび造滓材から
なる製鋼原料を装入してこれらを実質上溶解し，次いで
前記の半還元クロムペレットを該電気炉内の電極近傍の
スラグ層に少量づつ回分式にまたは連続式に装入すると
共に還元材を該スラグ層に装入することを特徴とする半
還元クロムペレットを用いたステンレス鋼の溶製方法。1. When melting stainless steel in an electric furnace using semi-reduced chromium pellets as a part or all of a chromium source, first, a steelmaking raw material comprising scrap and slag material is charged into the electric furnace. Then, these are substantially melted, and then the semi-reduced chromium pellets are charged little by little into the slag layer in the vicinity of the electrode in the electric furnace batchwise or continuously and the reducing material is charged into the slag layer. A method for melting stainless steel using semi-reduced chromium pellets, comprising:
り予備還元して得られた高温状態の半還元クロムホット
ペレットである特許請求の範囲第１項記載の溶製方法。2. The melting method according to claim 1, wherein the semi-reduced chromium pellets are high-temperature semi-reduced chromium hot pellets obtained by preliminary reduction in a solid-state reduction furnace.
するスラグ層には，さらに造滓材が装入される特許請求
の範囲第１項または第２項記載の溶製方法。3. The melting method according to claim 1, wherein a slag material is further charged into the slag layer in which the semi-reduced chromium pellets and the reducing material are charged.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62113681A JPH0791616B2 (en) | 1987-05-12 | 1987-05-12 | Melting method of stainless steel using semi-reduced chromium pellets |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62113681A JPH0791616B2 (en) | 1987-05-12 | 1987-05-12 | Melting method of stainless steel using semi-reduced chromium pellets |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63282236A JPS63282236A (en) | 1988-11-18 |
| JPH0791616B2 true JPH0791616B2 (en) | 1995-10-04 |
Family
ID=14618476
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62113681A Expired - Lifetime JPH0791616B2 (en) | 1987-05-12 | 1987-05-12 | Melting method of stainless steel using semi-reduced chromium pellets |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0791616B2 (en) |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5579817A (en) * | 1978-12-07 | 1980-06-16 | Nippon Steel Corp | Refining method for stainless steel using semi-reduced chromium pellet |
| AU552070B2 (en) * | 1981-10-19 | 1986-05-22 | Council For Mineral Technology | Producing and treating ferro chrome by arc thermal plasma |
-
1987
- 1987-05-12 JP JP62113681A patent/JPH0791616B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63282236A (en) | 1988-11-18 |
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