JPH01252708A - Method for operating iron bath type smelting reduction furnace - Google Patents

Abstract

PURPOSE:To improve secondary combustion ratio and to prevent spout of molten slag by specifying diameter of spouting part of bottom blowing gas on the molten slag surface, diameter of spreading of O2 gas on the molten slag with top blowing lance, recessed depth of the molten slag with the top blowing oxygen, etc., at the time of producing molten iron with iron oxide and coal as reducing agent in an iron bath type smelting reduction furnace. CONSTITUTION:Under condition of coexisting molten iron (molten pig) 4 and the molten slag 5 in the converter type refining furnace 1 having the bottom blowing tuyeres 2 and the oxygen top blowing lance 2, while blowing N2 or O2 from the bottom blowing tuyeres 2 and blowing oxygen from the top blowing lance 3, the iron oxide 6 and the coal 7 as reducing agent are charged from the furnace top part and the iron oxide is reduced to produce the molten pig 4. In this case, at the time of using l1 for the diameter spouting with the bottom blowing gas on the surface of the molten slag 5 and D for inner diameter, the relation between both is specified so as to become 0.6D<l1<0.9D, and at the time of using l2 for the diameter spreading with the top blowing oxygen in the surface of the molten slag 5, it is specified so as to become l2<0.8l1. Further, relation between the recessed depth Ls of the molten slag 5 with the top blowing O2 and thickness Hs of the molten slag 5, is held so as to become Ls<Hs. The iron oxide is reduction-refined under high secondary combustion ratio and low spout of the molten slag.

Description

【発明の詳細な説明】 ［産業上の利用分野］ 本発明は、鉄浴式溶融還元炉で、石炭を炭材として用い
る際の操業方法に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an operating method for using coal as a carbon material in an iron bath type smelting reduction furnace.

［従来の技術］ 特開昭６２−１８２２１４号は、鉄系合金溶湯の製造装
置で、従来溶鉱炉法で製造されていた溶銑を、よりコン
パクトな設備で製造する溶融還元炉に関する。[Prior Art] JP-A-62-182214 relates to an apparatus for producing molten iron-based alloys, and relates to a smelting reduction furnace for producing molten pig iron, which was conventionally produced by a blast furnace method, using more compact equipment.

しかしこの公報は製造装置に関するもので、具体的な操
業方法を示したものではない。However, this publication concerns the manufacturing equipment and does not indicate a specific operating method.

転炉型の反応容器内の溶融物に、酸化鉄と炭材とを添加
して吹酸すると、酸化鉄は還元されて溶鉄となる。この
際炭材としては例えば石炭等の揮発分の高い炭材（以下
高ＶＭ炭という）あるいは揮発分が１０％以下の炭材（
以下低ＶＭ炭という）例えばコークスが使用できる。When iron oxide and carbonaceous material are added to the molten material in a converter-type reaction vessel and acid is blown, the iron oxide is reduced and becomes molten iron. In this case, the carbonaceous material may be a carbonaceous material with a high volatile content such as coal (hereinafter referred to as high VM coal) or a carbonaceous material with a volatile content of 10% or less (hereinafter referred to as high VM coal).
For example, coke (hereinafter referred to as low VM coal) can be used.

低ＶＭ炭を使用すると高い二次燃焼率が得られるために
熱経済上は好ましいが、揮発分を少なくするための特別
な装置１例えばコークス炉等が必要であり、あるいは資
源の制約を伴う。The use of low VM coal is preferable from a thermoeconomic point of view since a high secondary combustion rate can be obtained, but it requires a special device 1 such as a coke oven to reduce volatile content, or is accompanied by resource constraints.

高ＶＭ炭はコークス炉等の前処理設備が不必要でまた安
価であるが１反応容器内に加えると、揮発するＣやＨに
よって二次燃焼率が低くなる等の問題点がある。High VM coal does not require pretreatment equipment such as a coke oven and is inexpensive, but when added to a single reaction vessel, there are problems such as a low secondary combustion rate due to volatilized C and H.

特開昭５９−１５３８１９号は、炭材を有効に燃焼させ
る技術に関し、溶融還元法でも実施できるが、この公報
は高ＶＭ炭を使用した際の二次燃焼率を高める技術等を
記載したものではない。JP-A No. 59-153819 describes a technique for effectively burning carbonaceous materials, which can also be carried out by the smelting reduction method, but this publication describes a technique to increase the secondary combustion rate when using high VM coal. isn't it.

［発明が解決しようとする課Ｍ］ 本発明は、鉄浴式溶融還元炉において、二次燃焼率を高
く確保しながら、さらに後で述べる如くスラグの泡立ち
を抑制して、石炭を炭材として使用する操業方法を開示
するものである。[Problem M to be solved by the invention] The present invention provides a method for using coal as a carbon material in an iron bath type smelting reduction furnace while ensuring a high secondary combustion rate and suppressing foaming of slag as described later. Discloses the operating method used.

［課題を解決するための手段］ 第１図は鉄浴式溶融還元炉の例を示す図である。[Means to solve the problem] FIG. 1 is a diagram showing an example of an iron bath type melting reduction furnace.

反応容器１は耐火物で内張すされた転炉状で、炉の下部
には底吹羽口２を備え底吹ガス、例えばＮ２ガスや０２
ガスを吹込む、３は吹錬用の酸素ランスで上吹酸素を吹
込む、４は溶鉄、５は溶融スラグである０反応容器１内
の溶鉄及び溶融スラグよりなる溶融物に酸化鉄６や炭材
７を加えて、酸素ランス３より上吹酸素を吹込み、底吹
羽口２より底吹ガスを吹込むと、酸化鉄は還元されて溶
鉄となり溶鉄量が増加する。溶鉄４が所定の溶鉄量に達
すると出湯する。出湯した溶湯は例えば別に設けた製鋼
炉で脱炭・精錬される。最初の溶鉄や溶融スラグは例え
ば前回の出湯に際して、溶鉄や溶融スラグを全量は出湯
しないで、一部を反応容器内に残留せしめて得られる。The reaction vessel 1 is in the form of a converter lined with refractory material, and is equipped with a bottom blowing tuyere 2 in the lower part of the furnace to supply a bottom blowing gas such as N2 gas or 02 gas.
3 blows in top-blown oxygen using an oxygen lance for blowing; 4 is molten iron; 5 is molten slag; iron oxide 6 and When the carbonaceous material 7 is added, top-blown oxygen is blown from the oxygen lance 3, and bottom-blown gas is blown from the bottom-blown tuyere 2, the iron oxide is reduced to become molten iron, and the amount of molten iron increases. When the molten iron 4 reaches a predetermined amount, it is tapped. The tapped molten metal is decarburized and refined, for example, in a separately provided steelmaking furnace. The initial molten iron or molten slag is obtained, for example, by not tapping the entire amount of the molten iron or molten slag during the previous tapping, but leaving a portion of the molten iron or molten slag remaining in the reaction vessel.

反応容器１内に加えられた炭材７は、上吹酸素によって
スラグに巻き込まれ、スラグ中で酸化鉄を還元する。炭
材７が低ＶＭ炭の場合はスラグに巻きこまれる歩留りが
安定し、下記（１）式で示される二次燃焼率（η）が高
い。The carbonaceous material 7 added into the reaction vessel 1 is drawn into the slag by top-blown oxygen, and reduces iron oxide in the slag. When the carbonaceous material 7 is a low VM coal, the yield of being rolled into slag is stable, and the secondary combustion rate (η) shown by the following equation (1) is high.

η＝　（（Ｃｏ、　＋ｎ、ｏ）　／　（ＣＯ２４ＧＯ＋
Ｈ，Ｏ＋８２　））　Ｘ　１００・・・（１）但しＣｏ
、、　Ｎ２０．　Ｃｏ、　Ｈ，は排出ガス中の各々の容
積％。しかし炭材７が石炭のような高ＶＭ炭の場合は、
揮発分が多いために、炭材の反応速度が不安定で、特別
の工夫を行わないと、スラグに巻き込まれる炭材の歩留
りが変動し、又高い二次燃焼率が得られず、又スラグに
巻きこまれる石炭の歩留りが低いとスラグ中の炭材量が
低下してスラグが泡立つために操業が不安定となる。従
って本発明では操業を下記の如くに制御する。即ち、ス
ラグ浴面における底吹ガスの噴出部直径Ｑ４を反応容器
の内径りに対して、０．６Ｄ＜　１２．＜０．９Ｄとし
、スラグ浴面における上吹酸素の拡がり直径Ｑ２を、Ｑ
、＜０．１３Ｑ１とし、上吹酸素によるスラグキャビテ
ィー深さＬｓをスラグ厚さＨｓに対して　Ｌｓ＜Ｈｓと
して吹酸する。η= ((Co, +n, o) / (CO24GO+
H, O+82)) X 100...(1) However, Co
,, N20. Co, H, are each volume % in exhaust gas. However, if the carbon material 7 is high VM coal such as coal,
Due to the large volatile content, the reaction rate of the carbonaceous material is unstable, and unless special measures are taken, the yield of the carbonaceous material caught in the slag will fluctuate, and a high secondary combustion rate cannot be obtained, and the slag If the yield of coal rolled into the slag is low, the amount of carbonaceous material in the slag will decrease and the slag will bubble, making operations unstable. Therefore, in the present invention, the operation is controlled as follows. That is, the diameter Q4 of the bottom-blowing gas outlet on the slag bath surface is 0.6D<12. <0.9D, and the spread diameter Q2 of top-blown oxygen on the slag bath surface is Q
, <0.13Q1, and the slag cavity depth Ls due to top-blown oxygen is blown with Ls<Hs relative to the slag thickness Hs.

Ｑｏは炉内を観察しても把握出来るが、予め設定された
計算式から求めてもよい。Ｑ２やＬｓは酸素ランス３の
送酸条件や、上下位置の調整によって所望の如くに容易
に設定できる。Qo can be determined by observing the inside of the furnace, but it may also be determined from a preset calculation formula. Q2 and Ls can be easily set as desired by adjusting the oxygen supply conditions of the oxygen lance 3 and its vertical position.

又Ｈｓも、スラブの量を十分確保する事によって、Ｌ　
ｓ　＜　Ｈｓとなし得る。In addition, Hs can also be reduced by ensuring a sufficient amount of slab.
s < Hs.

［作用コ 本発明では吹錬をＬ　ｓ　＜　Ｈｓで行う。スラグキャ
ビティー深さＬｓが深くなり過ぎて、酸素ランス３から
のガス流が溶鉄に吹きつけられると、溶鉄や溶鉄中のＣ
を再度酸化するため、還元効率が下るし、二次燃焼率も
低くなる。従って本発明ではＬ　ｓ　＜　Ｈｓとする。[Operations] In the present invention, blowing is performed with L s < Hs. If the slag cavity depth Ls becomes too deep and the gas flow from the oxygen lance 3 is blown onto the molten iron, the molten iron or C in the molten iron
is oxidized again, reducing reduction efficiency and secondary combustion rate. Therefore, in the present invention, L s < Hs.

次に本発明ではＱｌを０．６０−０．９Ｄの範囲とし、
且つＱ２を０．８ｌ工以下として操業する。第２図はＱ
ｌや０□を変えて操業した際の、二次燃焼率ηやスラグ
フォーミングの観察結果を示す図である。Next, in the present invention, Ql is set in the range of 0.60-0.9D,
In addition, the plant will be operated with Q2 of 0.8 liters or less. Figure 2 is Q
It is a figure which shows the observation result of secondary combustion rate (eta) and slag foaming when operating by changing l and 0□.

第２図にみられる如く、Ｑ□／Ｄが０．６〜０．９で且
つＱ２ＩＱ、が０．８以下の場合は、二次燃焼率ηは何
れも４５％以上で、又石炭のスラグへの巻き込みも安定
し、スラグの泡立ちが発生する事も少なく、安定な操業
が可能となる。As shown in Figure 2, when Q□/D is 0.6 to 0.9 and Q2IQ is 0.8 or less, the secondary combustion rate η is 45% or more, and the coal slag The entrainment into the slag is stable, there is little occurrence of slag bubbling, and stable operation is possible.

この理由については下記の如くと思考される。The reason for this is thought to be as follows.

反応容器内をｗｔ察の結果、Ｑ１／Ｄが０．６〜０．９
で且つＱ、ＩＱ、が０．８以下の場合は、添加した石炭
は反応容器の炉壁側に吹き寄せられて偏在している。As a result of wt inspection inside the reaction vessel, Q1/D was 0.6 to 0.9.
When Q and IQ are 0.8 or less, the added coal is blown toward the furnace wall side of the reaction vessel and is unevenly distributed.

反応容器の炉壁側に石炭を偏在させると、石炭の反応は
緩やかで、安定してスラグ中に巻き込まれる。２．／Ｄ
が０．６以下の場合やＱ２／Ｑ１が０．８以上の場合は
、反応容器内の石炭は炉の中心側にも存在することが観
察されるが、この状態では石炭には上吹酸素が強く吹き
つけられて、スラグ上で燃焼してスラグ中に巻き込まれ
る量が不安定で、又揮発分が二次燃焼率を低下せしめる
に至る。When coal is unevenly distributed on the furnace wall side of the reaction vessel, the reaction of the coal is gradual and stably involved in the slag. 2. /D
When Q2/Q1 is 0.6 or less, or Q2/Q1 is 0.8 or more, it is observed that the coal in the reaction vessel is also present at the center of the furnace, but in this state, the coal has no top-blown oxygen. is strongly blown onto the slag, the amount of it being combusted on the slag and being drawn into the slag is unstable, and the volatile matter reduces the secondary combustion rate.

［実施例コ 第３図に示す如く、半径３ｍの反応容器内に溶鉄を５０
トン、スラグ（ＣａＯ／５ｉ０２：１．２．　ＭｇＯ：
１５％、ＡＱ２０３：１５％）を２０トン装入し、上吹
酸素：８５０ＯＮｍ１／ｈ、底吹酸素：５０ＯＮｍ３／
ｈを吹込んだ１羽口は容器底面の中心から１．４６ｍの
位置に４本を点対象に設置した。この時のスラグ厚みは
１０００ｍｍ、上吹ジェットによるスラグキャビティー
深さは６００ｍｍであった。またＱｌは３．９ｍ、Ｑ２
は３．０ｍである。石炭は１ｍｍ〜２０ｍｍの粒度のも
のを１３トン／ｈ、鉄鉱石は１２トン／ｈを炉上から装
入し、１時間の操業を行った。その間二次燃焼率は４５
〜５５％と安定して推移し、その結果７．６トンの溶鉄
が生成した。[Example 1] As shown in Figure 3, molten iron was poured into a reaction vessel with a radius of 3 m.
tons, slag (CaO/5i02:1.2.MgO:
15%, AQ203: 15%), top-blown oxygen: 850ONm1/h, bottom-blown oxygen: 50ONm3/
Four tuyeres into which h was injected were installed symmetrically at positions 1.46 m from the center of the bottom of the container. The slag thickness at this time was 1000 mm, and the depth of the slag cavity created by the top blowing jet was 600 mm. Also, Ql is 3.9m, Q2
is 3.0m. 13 tons/h of coal with a particle size of 1 mm to 20 mm and 12 tons/h of iron ore were charged from the top of the furnace, and the operation was carried out for 1 hour. Meanwhile, the secondary combustion rate is 45
It remained stable at ~55%, and as a result, 7.6 tons of molten iron was produced.

［発明の効果］ 本発明によって、鉄浴式溶融還元炉において、石炭を炭
材として使用しても、高い二次燃焼率が確保でき、又ス
ラグ泡立ちの発生を抑止した操業が可能となる。[Effects of the Invention] According to the present invention, even if coal is used as the carbon material in an iron bath type smelting reduction furnace, a high secondary combustion rate can be ensured, and operation can be performed while suppressing the occurrence of slag foaming.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は本発明で用いられる鉄浴式溶融還元炉の例を示
す図。 第２図は操業条件と二次燃焼率及びスラグ泡立ちの関係
を示す図、 第３図は実施例の吹錬を示す図 である。 特許出願人　　新日本製鐵株式会社FIG. 1 is a diagram showing an example of an iron bath type melting reduction furnace used in the present invention. FIG. 2 is a diagram showing the relationship between operating conditions, secondary combustion rate, and slag foaming, and FIG. 3 is a diagram showing blowing in an example. Patent applicant Nippon Steel Corporation

Claims (1)

【特許請求の範囲】[Claims] 石炭を炭材として用いる鉄浴式溶融還元炉において、ス
ラグ浴面における底吹ガスの噴出部直径ｌ＿１を反応容
器の内径Ｄに対して、０．６Ｄ＜ｌ＿１＜０．９Ｄとし
、スラグ浴面における上吹酸素の拡がり直径ｌ＿２を、
ｌ＿２＜０．８ｌ＿１とし、上吹酸素によるスラグキャ
ビティー深さＬ＿ｓをスラグ厚さＨ＿ｓに対してＬ＿ｓ
＜Ｈ＿ｓとして吹酸する事を特徴とする、鉄浴式溶融還
元炉の操業方法In an iron bath type smelting reduction furnace using coal as a carbonaceous material, the diameter l_1 of the bottom-blown gas ejection part at the slag bath surface is set to 0.6D<l_1<0.9D with respect to the inner diameter D of the reaction vessel, and the slag bath surface The spread diameter l_2 of top-blown oxygen at
l_2<0.8l_1, and the slag cavity depth L_s due to top-blown oxygen is L_s relative to the slag thickness H_s.
<A method of operating an iron bath type smelting reduction furnace characterized by blowing acid as H_s