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JP3825603B2 - Zinc enrichment method for steelmaking dust - Google Patents

Zinc enrichment method for steelmaking dust Download PDF

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Publication number
JP3825603B2
JP3825603B2 JP2000055625A JP2000055625A JP3825603B2 JP 3825603 B2 JP3825603 B2 JP 3825603B2 JP 2000055625 A JP2000055625 A JP 2000055625A JP 2000055625 A JP2000055625 A JP 2000055625A JP 3825603 B2 JP3825603 B2 JP 3825603B2
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Prior art keywords
zinc
hot metal
dust
scrap
steelmaking dust
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JP2001240919A (en
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進 務川
克巳 近藤
晃一 松本
正 今井
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Nippon Steel Corp
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Nippon Steel Corp
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    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00Technologies related to metal processing
    • Y02P10/20Recycling

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  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
  • Carbon Steel Or Casting Steel Manufacturing (AREA)
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Description

【0001】
【発明の属する技術分野】
本発明は、亜鉛含有スクラップから効率的に亜鉛成分の含有率が高く、亜鉛一次精錬用の亜鉛原材料としてリサイクル容易な製鋼ダストを得る製鋼ダストの亜鉛濃縮方法に関するものである。
【0002】
【従来の技術】
従来から、省資源を目的として鉄スクラップのリサイクルが図られている。この鉄スクラップには、亜鉛系めっき鋼板などの亜鉛成分(特に金属亜鉛)を含むものが多いため、亜鉛含有スクラップを用いて鋼を製造する場合には、亜鉛成分は除去することが好ましい。そこで、スクラップを利用して鋼を製造する場合には、鋼の成分調整を行う精錬工程において亜鉛の回収を行うのが普通であり、このため、例えば、特開平7-26317 号公報や特開平10-121122 号公報や特開昭63-62813号公報などに開示されているように、種々の回収方法が提案されている。
【0003】
前記した特開平7-26317 号公報に開示されている技術は、脱珪脱燐工程の溶銑中に亜鉛スクラップを装入して高濃度の亜鉛含有ダストを回収するものであるが、この方法による場合は一部の亜鉛が溶銑中に溶解し、この溶解した亜鉛を蒸発、除去するのに長時間要するという問題点があった。また、回収したダスト中の亜鉛濃度は9.3%程度と低濃度であり、25%以上,好ましくは40%程度の濃度が必要とされる亜鉛一次精錬用の亜鉛源としてリサイクルすることが工業的に困難であった。 尚、以下の記載において、%とppm の記載は質量比とする。
また、特開平10-121122 号公報に開示されている技術は、亜鉛含有ダストを溶銑中に不活性ガスで吹込み高濃度の亜鉛を回収するものであるが、これによる場合には亜鉛の還元蒸発に溶銑の顕熱のみ利用するので、亜鉛を確実に回収するのには鋼精錬プロセスとは別プロセスを設ける必要があり、また、分解反応に伴う熱ロスが増加して熱的余裕度が減少するとともに、亜鉛が銑鉄に溶解して次工程で発生するダストの汚染を招くという問題点があった。更には、回収した亜鉛含有ダストは前記した方法と同様低濃度であって、亜鉛一次精錬業へリサイクルすることは困難であった。
また、特開昭63-62813号公報に開示されている技術は、転炉内にスクラップとともに電気炉ダストや亜鉛メッキドロス等酸化物の亜鉛含有廃棄物を投入し、溶銑によりスクラップ溶解、吹錬する際に発生したダスト中の亜鉛を回収するものであるが、このような亜鉛含有廃棄物では亜鉛は酸化物であり容易に還元されず、また還元は溶銑中Cとの反応であり、不可避的に亜鉛が溶銑中に溶解して次工程でのダストを汚染するという問題点があった。更には、回収した亜鉛含有ダストは前記した方法と同様に低濃度であって、亜鉛一次精錬業用にリサイクルして使用することが工業的に困難であった。
【0004】
【発明が解決しようとする課題】
本発明は上記のような従来の問題点を解決して、鋼の精錬工程中の予備処理工程で亜鉛含有スクラップから効率的に亜鉛成分(例えばスクラップに付着した金属亜鉛)を製鋼ダストに回収して亜鉛一次精錬業にリサイクルしやすくするとともに、次の脱炭処理を行う転炉に亜鉛成分が持ち込まれることをなくすことができる製鋼ダストの亜鉛濃縮方法を提供することを目的として完成されたものである。
【0005】
【課題を解決するための手段】
上記の課題を解決するためになされた本発明の製鋼ダストの亜鉛濃縮方法は、亜鉛含有スクラップを装入してある溶銑予備処理炉に溶銑を装入後、この溶銑予備処理炉に予め亜鉛含有スクラップを装入してある溶銑予備処理炉にて、亜鉛含有スクラップ中の金属亜鉛を加熱蒸発させ、その後に溶銑を装入して、溶銑予備処理炉から発生する亜鉛酸化物を含む製鋼ダストを回収して得られた亜鉛酸化物を含む製鋼ダストを、石灰石および/またはソーダ灰とともに吹込み、その上方から酸素を加えてこの溶銑予備処理炉から発生する高濃度化された亜鉛成分を含む製鋼ダストを回収することを特徴とするものである。
【0007】
【発明の実施の形態】
以下に、図面を参照しつつ本発明の好ましい実施の形態を示す。
図中、1は鋼の精錬工程における溶銑予備処理炉、 2aは溶銑予備処理炉1に設けられたダストの吸引用フード、3は溶銑予備処理炉1にスクラップを装入するためのスクラップシュートであり、これらの構成は従来のものと同じであるが、本発明はこのような溶銑予備処理炉1で溶銑の予備処理を行った後、転炉4で脱炭処理を行う鋼の精錬工程において、高温の溶銑予備処理炉1に予め亜鉛含有スクラップ10を装入し、亜鉛含有スクラップ10中の亜鉛成分(特に金属亜鉛)を加熱蒸発させ、この溶銑予備処理炉1から発生する前記亜鉛成分を含む精錬ダストを回収して、その後に溶銑11を装入して溶銑予備処理(例えば溶銑の脱珪、脱燐処理等)を行い、製鋼ダスト中の亜鉛濃度を高濃度化する点に特徴がある。
【0008】
即ち、溶銑に亜鉛含有スクラップを添加するのではなく、亜鉛含有スクラップを先に装入後に溶銑11を装入することにより、亜鉛含有スクラップに付着している亜鉛成分(特に金属亜鉛)を炉体顕熱により加熱して蒸発させ、この溶銑予備処理炉から発生する高濃度の亜鉛成分(酸化亜鉛)を含む精錬ダストを吸引用フード2aを介して回収して、製鋼ダストに亜鉛を濃縮せしめ、製鋼ダストを亜鉛原料として利用可能にしたものである。この結果、回収した精錬ダスト中における亜鉛濃度は25%以上、 更に好ましくは40%以上と高くなって亜鉛精鉱として利用可能となり、また、溶銑中にスクラップより溶解残留する亜鉛量も少なくなるため、後工程の転炉に亜鉛が持ち越されることによる弊害をも解決することができることとなる。
【0009】
なお、このような予備処理工程においては、前記した溶銑予備処理炉1が亜鉛含有スクラップ10を装入した場合に、亜鉛含有スクラップに付着している金属亜鉛を炉体顕熱により加熱して蒸発させるのに十分な顕熱を有していることが好ましい。そのためには、外部からの加熱手段を用いて溶銑予備処理炉1を亜鉛の昇華温度を超える所定の温度に達するようにしてもよいが、溶銑の予備処理を複数回好ましくは4回以上連続運転した後に本発明を実施すれば、外部からの加熱手段がなくても溶銑予備処理炉1を金属亜鉛の加熱蒸発に十分な温度とすることができるので一層好ましい。
【0010】
また、このようにして得られた精錬ダストを、再びフィードバックして溶銑予備処理炉1 中に吹込むようにすれば、回収されるダスト中における亜鉛濃度は益々高いものとなり、より濃度の高い高品質で亜鉛一次精錬業にリサイクル可能な製鋼ダストを得ることが可能となる。
即ち、図2に示されるように、亜鉛含有スクラップを装入してある溶銑予備処理炉1に溶銑を装入後、この溶銑予備処理炉1中に前記した方法により得られた酸化亜鉛を含む精錬ダストを、石灰石および/またはソーダ灰とともに吹込みノズル5を介して溶銑中に吹込み、その上方から溶銑の脱珪、脱燐に必要な酸素をランス4により加えて攪拌し、溶銑の脱珪脱燐処理を行い、この溶銑予備処理炉1から発生する高濃度化された亜鉛成分を含む精錬ダストを吸引用フード2bを介して回収して製鋼ダスト中へ亜鉛(金属亜鉛)を濃縮し亜鉛一次精錬用にリサイクル可能ならしめる。
この場合、上記ダストを窒素等の不活性ガスと石灰石(CaCO3 )および/またはソーダ灰(Na2CO3)とともに吹込むと、これらの物質は溶銑と下記のように反応して多量のCOガスを発生する。
【0011】
【化1】

Figure 0003825603
備考:は溶銑中に溶解したCを示す。
【化2】
Figure 0003825603
【0012】
本発明者らの基礎実験によると、ZnO の還元・蒸発反応はCによる還元より雰囲気中COガスによる反応が主であることが判明しており、上記反応で生成したCOガスによって下記のようにZnO の還元は促進される。
【化3】
Figure 0003825603
備考:(g) はガスを示す。
更に、生成したZn (g)蒸気はCOガス気泡中に希薄にしか存在しないため、下記反応式で示す溶銑中へのZnの溶解は少ない。
【化4】
Figure 0003825603
備考:Znは溶銑中に溶解したZnを示す。
【0013】
この時、CaCO3 および/またはNa2CO3吹込み速度を高く保つことによって、固(ダスト粒子)−気(COガス)−液(溶銑)混相流中のCOガス割合が高く保たれるとともに、表面のスラグが除去されて裸湯状態となる。これによりZn蒸気の溶銑中への溶解、およびスラグへのトラップを少なくできるので、金属亜鉛の回収効率を上げることができるとともに、スラグが亜鉛で汚染されることもなく再利用上の問題を生じることもなく好ましい。この結果、酸化亜鉛含有ダストを吹込んでも溶銑の亜鉛による汚染、即ち溶銑中に亜鉛が残留することも抑制されることになる。
【0014】
このように本発明は、溶銑予備処理炉1で溶銑予備処理を行った後、転炉で脱炭処理を行う鋼の精錬工程において、予め亜鉛(主として金属亜鉛)を含有するスクラップを装入してある溶銑予備処理炉1にて亜鉛含有スクラップ中の金属亜鉛を加熱蒸発させ、その後に溶銑を装入して、溶銑予備処理炉1から発生する酸化亜鉛を含む製鋼ダストを回収することにより、亜鉛含有スクラップから効率的に亜鉛元素の含有率が高い亜鉛一次精錬業向けにリサイクル可能な製鋼ダストを低ランニングコストで得ることができ、しかも、溶銑11中に亜鉛が残らないので、次の脱炭処理を行う転炉に亜鉛元素( 金属亜鉛およびまたは酸化亜鉛) が持ち込まれることにより生じる弊害を大幅に減らすことができる。更には、亜鉛を含有するスクラップと亜鉛を含有しないスクラップとを分別することなく使用できるため、選別の費用も不要となり、また既存の製鋼工程に新たな設備費用や運転費用等をほとんどかけず僅かに溶銑予備処理炉に吹込み設備を設けるのみでよいという利点もある。
【0015】
【実施例】
以下に、本発明の実施例を示す。
[実施例1]
まず、亜鉛含有スクラップ質量20t を外部からの加熱手段を用いて950℃程度に加熱してある転炉タイプの溶銑予備処理炉に装入した。この時、ダスト補集集塵機を運転し、炉外に吹き上がるダストを回収し始める。引き続き、溶銑質量290t を装入し、炭酸カルシウムとダストからなる粉体を窒素ガスにより底吹き羽口より吹込み開始するとともに、生石灰、鉄鉱石等の精錬剤を添加し、上から酸素ガスを吹付け開始し、溶銑の脱珪、脱燐処理を600sec 行った。得られた溶銑中の珪素、燐は各々質量が0.32% から0.01% 以下に、0.097%から0.014%に低下した。また、溶銑中の亜鉛濃度は0.5ppm以下であり、満足に亜鉛元素の分離ができていた。そして、ダスト補集集塵機により回収された製鋼ダスト中には加熱により蒸発した亜鉛含有スクラップ中の亜鉛元素が50% と高濃度で含まれており、亜鉛一次精錬業向けにリサイクル可能な材料であることが確認できた。
【0016】
[実施例2]
1チャージあたり、スクラップ質量8〜38t を転炉タイプの溶銑予備処理炉に装入した。この時、ダスト補集集塵機を運転し、炉外に吹き上がるダストを回収し始める。1チャージあたり溶銑質量262〜291t を装入し、炭酸カルシウムと前工程で回収した亜鉛成分を含む精錬ダストを窒素ガスとともに底吹き羽口より吹込みながら、生石灰等の精錬剤を添加し、上から酸素ガスを吹付け開始し、1チュージあたり300〜600sec 間の脱珪脱燐処理を行った。溶銑中の初期珪素濃度は0.25〜0.75% 、りん濃度は0.078 〜0.10% であったが、処理後の珪素濃度は0.01% 以下、りん濃度は0.011 〜0.021%、亜鉛濃度0.5ppm以下となり、また、スラグ中の亜鉛濃度は0.1%以下であった。以上の工程中ダスト補集集塵機で回収した亜鉛成分を含む精錬ダストを溶銑予備処理炉にフィードバックさせることを7回繰り返すことにより、最終的に亜鉛濃度が62% の亜鉛一次精錬業向けにリサイクル可能な材料が得られた。
【0017】
[実施例3]
1チャージあたり、スクラップ質量10〜37t を転炉タイプの溶銑予備処理炉に装入した。この時、ダスト補集集塵装置で発生するダストをバグフィルターにトラップする。引き続き、1チャージあたり溶銑質量268〜301t を装入し、炭酸カルシウムと製鉄ダストと窒素ガスとともに底吹き羽口より吹込みながら、生石灰等の精錬剤を上方添加し、メインランスから酸素ガスを上吹きして脱珪脱燐処理を420〜660sec 間行った。更に、その後、酸素ガス上吹き停止し、CaO とNa2CO3を85:15 の質量比で混合したフラックスと、前記したバグフィルターにより回収された製鋼ダストを吹込みながら脱硫処理を300sec 間行った。前記した脱珪・脱燐処理中のCaCO3 の平均吹込み速度は1.6kg/s 、脱硫処理中のフラックス吹込み速度は6.6kg/s 以上であり、またダスト吹込み速度は脱珪・脱燐処理中が4.6 〜5.0kg/s であった。溶銑の初期珪素、りん、硫黄質量濃度は、各々0.35〜0.67% 、0.062 〜0.097%、0.01〜0.02% であったが、処理後の溶銑の珪素、りん、硫黄、亜鉛質量濃度は、各々0.01% 以下、0.012 〜0.022%、0.003 〜0.007%、2ppm以下であり、スラグ中の亜鉛質量濃度は0.1%以下であった。また、バグフィルターにより回収した製鋼ダストを溶銑予備処理炉にフィードバックさせることを7回繰り返して前記処理を行った結果、最終的に回収した製鋼ダスト中のZnO 質量濃度は52% であった。
【0018】
【発明の効果】
本発明は以上の説明からも明らかなように、亜鉛含有スクラップから効率的に亜鉛成分の含有率が高い亜鉛一次精錬業向けにリサイクル可能な材料を低ランニングコストで製造でき、しかも精錬中の溶銑中に亜鉛が残らないので、後工程の転炉に亜鉛成分が持ち込まれることにより生じる弊害をなくすことができ、更には、亜鉛含有スクラップと亜鉛を含有しないスクラップとを分別することなく使用できるため、選別の費用も不要となる。また、既存の精錬工程に新たに設備費用や運転費用等を殆どかけず、僅かに吹込み設備を追加するのみでよいという利点もある。
よって本発明は効率的に亜鉛含有スクラップから製鋼ダストに亜鉛を濃縮することができるので、亜鉛一次精錬業向けにリサイクル可能な材料を得る方法として、産業の発展に寄与するところは極めて大である。
【図面の簡単な説明】
【図1】本発明の実施の形態を示す正面図である。
【図2】その他の実施の形態を示す正面図である。
【符号の説明】
1 溶銑予備処理炉
2a 吸引用フード
2b 吸引用フード
3 スクラップシュート
4 ランス
5 吹込みノズル
6 ホッパー
10 亜鉛含有スクラップ
11 溶銑[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for concentrating zinc in steelmaking dust to obtain steelmaking dust that has a high zinc content efficiently from zinc-containing scrap and is easily recyclable as a zinc raw material for primary zinc refining.
[0002]
[Prior art]
Conventionally, iron scrap has been recycled for the purpose of saving resources. Since many of these iron scraps contain a zinc component (particularly metallic zinc) such as a zinc-based plated steel sheet, it is preferable to remove the zinc component when producing steel using zinc-containing scrap. Therefore, when steel is manufactured using scrap, it is common to recover zinc in a refining process in which the steel components are adjusted. For this reason, for example, Japanese Patent Laid-Open No. 7-26317 and Japanese Patent Laid-Open No. As disclosed in JP-A-10-121122 and JP-A-63-62813, various recovery methods have been proposed.
[0003]
The technique disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 7-26317 is for recovering high-concentration zinc-containing dust by charging zinc scrap into the hot metal in the desiliconization and dephosphorization process. In some cases, some zinc was dissolved in the hot metal, and it took a long time to evaporate and remove the dissolved zinc. Moreover, the zinc concentration in the recovered dust is as low as about 9.3%, and it is industrially possible to recycle as a zinc source for primary refining of zinc that requires a concentration of 25% or more, preferably about 40%. It was difficult. In the following description,% and ppm are mass ratios.
Further, the technique disclosed in Japanese Patent Laid-Open No. 10-121122 is for recovering high concentration of zinc by blowing zinc-containing dust into the hot metal with an inert gas. Since only the sensible heat of the hot metal is used for evaporation, it is necessary to provide a process separate from the steel refining process in order to reliably recover zinc, and the heat loss associated with the decomposition reaction increases and the thermal margin increases. In addition to the decrease, there was a problem that zinc was dissolved in pig iron and caused contamination of dust generated in the next process. Furthermore, the recovered zinc-containing dust has a low concentration as in the above-described method, and it was difficult to recycle it to the primary zinc refining industry.
In addition, the technology disclosed in Japanese Patent Laid-Open No. 63-62813 discloses that zinc-containing wastes of oxides such as electric furnace dust and galvanized dross are introduced into the converter together with scrap, and the scrap is melted and blown by hot metal. In such a zinc-containing waste, zinc is an oxide and is not easily reduced, and the reduction is a reaction with C in the hot metal and is unavoidable. However, there was a problem that zinc was dissolved in the hot metal and contaminated dust in the next process. Furthermore, the recovered zinc-containing dust has a low concentration as in the above-described method, and it has been industrially difficult to recycle and use it for the primary zinc refining industry.
[0004]
[Problems to be solved by the invention]
The present invention solves the conventional problems as described above, and efficiently recovers zinc components (for example, metallic zinc adhering to the scrap) from the zinc-containing scrap into the steelmaking dust in the pretreatment process during the steel refining process. It was completed for the purpose of providing a method for concentrating zinc in steelmaking dust that makes it easy to recycle to the primary zinc refining industry and eliminates the introduction of zinc components into the converter that performs the next decarburization treatment. It is.
[0005]
[Means for Solving the Problems]
The method for concentrating zinc in steelmaking dust of the present invention made to solve the above-mentioned problems is that the hot metal pretreatment furnace charged with zinc-containing scrap is charged with hot metal, and then the hot metal pretreatment furnace contains zinc in advance. In the hot metal pretreatment furnace where the scrap is charged, the metal zinc in the zinc-containing scrap is heated and evaporated, and then the hot metal is charged to produce steelmaking dust containing zinc oxide generated from the hot metal pretreatment furnace. Steelmaking dust containing zinc oxide containing zinc oxide obtained by injecting together with limestone and / or soda ash and adding oxygen from above is produced from this hot metal pretreatment furnace. It is characterized by collecting dust.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
In the figure, 1 is a hot metal pretreatment furnace in the steel refining process, 2a is a dust suction hood provided in the hot metal pretreatment furnace 1, and 3 is a scrap chute for charging scrap into the hot metal pretreatment furnace 1. The present invention is the same as the conventional one, but the present invention is a steel refining process in which the hot metal pretreatment furnace 1 performs the hot metal pretreatment and the converter 4 performs decarburization treatment. The zinc-containing scrap 10 is charged into the hot metal pretreatment furnace 1 in advance, the zinc component (particularly metallic zinc) in the zinc-containing scrap 10 is heated and evaporated, and the zinc component generated from the hot metal pretreatment furnace 1 is removed. It is characterized in that the refined dust is recovered, and then the hot metal 11 is charged and the hot metal pretreatment (for example, desiliconization and dephosphorization of the hot metal) is performed to increase the zinc concentration in the steelmaking dust. is there.
[0008]
That is, instead of adding zinc-containing scrap to the hot metal, the zinc component (especially metallic zinc) adhering to the zinc-containing scrap is introduced into the furnace body by charging the hot metal 11 after first charging the zinc-containing scrap. It is heated and evaporated by sensible heat, and the refined dust containing the high concentration zinc component (zinc oxide) generated from the hot metal pretreatment furnace is recovered through the suction hood 2a to concentrate the zinc in the steelmaking dust. Steelmaking dust can be used as a raw material for zinc. As a result, the zinc concentration in the recovered smelting dust becomes as high as 25% or more, more preferably 40% or more, so that it can be used as zinc concentrate, and the amount of zinc remaining in the molten iron from the scrap is reduced. Thus, the adverse effect of zinc carried over to the converter in the subsequent process can be solved.
[0009]
In such a pretreatment process, when the hot metal pretreatment furnace 1 is charged with the zinc-containing scrap 10, the metal zinc adhering to the zinc-containing scrap is heated and evaporated by sensible heat of the furnace body. It is preferable to have sufficient sensible heat to make it. For this purpose, the hot metal pretreatment furnace 1 may reach a predetermined temperature exceeding the sublimation temperature of zinc by using an external heating means, but the hot metal pretreatment is continuously operated a plurality of times, preferably four times or more. After that, it is more preferable to carry out the present invention because the hot metal pretreatment furnace 1 can be brought to a temperature sufficient for heating and evaporating the metallic zinc without any external heating means.
[0010]
In addition, if the refined dust obtained in this way is fed back and blown into the hot metal pretreatment furnace 1, the zinc concentration in the recovered dust will become higher and the higher concentration and higher quality. It becomes possible to obtain steelmaking dust that can be recycled to the primary zinc refining industry.
That is, as shown in FIG. 2, after hot metal is charged into the hot metal pretreatment furnace 1 charged with zinc-containing scrap, the hot metal pretreatment furnace 1 contains zinc oxide obtained by the method described above. The smelting dust is blown into the hot metal with the limestone and / or soda ash through the blowing nozzle 5, and oxygen necessary for desiliconization and dephosphorization of the hot metal is added through the lance 4 from above to stir the hot metal. Silica dephosphorization treatment is performed, and refined dust containing the highly concentrated zinc component generated from the hot metal pretreatment furnace 1 is recovered through the suction hood 2b to concentrate zinc (metal zinc) into the steelmaking dust. Make it recyclable for primary zinc refining.
In this case, when the above dust is blown together with an inert gas such as nitrogen and limestone (CaCO 3 ) and / or soda ash (Na 2 CO 3 ), these substances react with hot metal as described below to produce a large amount of CO. Generate gas.
[0011]
[Chemical 1]
Figure 0003825603
Remarks: C indicates C dissolved in the hot metal.
[Chemical 2]
Figure 0003825603
[0012]
According to the basic experiments of the present inventors, it has been found that the reduction / evaporation reaction of ZnO is mainly due to the CO gas in the atmosphere rather than the reduction by C. Reduction of ZnO is promoted.
[Chemical 3]
Figure 0003825603
Note: (g) indicates gas.
Furthermore, since the generated Zn (g) vapor is present only in a dilute manner in the CO gas bubbles, there is little dissolution of Zn in the hot metal shown by the following reaction formula.
[Formula 4]
Figure 0003825603
Remarks: Zn indicates Zn dissolved in the hot metal.
[0013]
At this time, by keeping the CaCO 3 and / or Na 2 CO 3 blowing speed high, the ratio of CO gas in the solid (dust particles) -gas (CO gas) -liquid (molten metal) mixed phase flow is kept high. The slag on the surface is removed, and it becomes a bare hot water state. This makes it possible to reduce the dissolution of Zn vapor in the hot metal and trap it in the slag, so that the recovery efficiency of metallic zinc can be increased and the slag is not contaminated with zinc, resulting in recycling problems. None is preferred. As a result, even if zinc oxide-containing dust is blown, contamination of the hot metal with zinc, that is, zinc remaining in the hot metal is suppressed.
[0014]
Thus, in the present invention, in the steel refining process in which hot metal pretreatment is performed in the hot metal pretreatment furnace 1 and decarburization is performed in the converter, scraps containing zinc (mainly metallic zinc) are charged in advance. In the hot metal pretreatment furnace 1, the metal zinc in the zinc-containing scrap is heated and evaporated, and then the hot metal is charged, and steelmaking dust containing zinc oxide generated from the hot metal pretreatment furnace 1 is recovered, Steelmaking dust that can be recycled from the zinc-containing scrap efficiently for the primary zinc refining industry, which has a high content of zinc element, can be obtained at low running cost. Moreover, since no zinc remains in the hot metal 11, The harmful effects caused by the introduction of elemental zinc (metal zinc and / or zinc oxide) into the converter for charcoal treatment can be greatly reduced. Furthermore, since scraps containing zinc and scraps not containing zinc can be used without separation, there is no need for sorting costs, and there is little additional equipment or operating costs for existing steelmaking processes. In addition, there is an advantage that it is only necessary to provide blowing equipment in the hot metal pretreatment furnace.
[0015]
【Example】
Examples of the present invention are shown below.
[Example 1]
First, 20 tons of zinc-containing scrap was charged into a converter-type hot metal pretreatment furnace heated to about 950 ° C. using an external heating means. At this time, the dust collecting dust collector is operated to start collecting the dust that blows out of the furnace. Subsequently, 290 t of hot metal mass was charged, and a powder consisting of calcium carbonate and dust was started to be blown from the bottom blowing tuyere with nitrogen gas, and a refining agent such as quicklime and iron ore was added, and oxygen gas was added from above. Spraying was started, and hot metal desiliconization and dephosphorization were performed for 600 seconds. The masses of silicon and phosphorus in the obtained hot metal respectively decreased from 0.32% to 0.01% or less and from 0.097% to 0.014%. The zinc concentration in the hot metal was 0.5 ppm or less, and the zinc element was satisfactorily separated. The steelmaking dust collected by the dust collecting dust collector contains 50% zinc element in the zinc-containing scrap evaporated by heating, and is a recyclable material for the primary zinc refining industry. I was able to confirm.
[0016]
[Example 2]
A scrap mass of 8 to 38 tons per charge was charged into a converter type hot metal pretreatment furnace. At this time, the dust collecting dust collector is operated to start collecting the dust that blows out of the furnace. Add refining agent such as quick lime while charging refining dust containing calcium carbonate and zinc component recovered in the previous process from the bottom blowing tuyere together with nitrogen gas. From this, oxygen gas was started to be sprayed, and desiliconization and phosphorus removal treatment was performed for 300 to 600 seconds per tude. The initial silicon concentration in the hot metal was 0.25 to 0.75% and the phosphorus concentration was 0.078 to 0.10%, but the silicon concentration after treatment was 0.01% or less, the phosphorus concentration was 0.011 to 0.021%, and the zinc concentration was 0.5 ppm or less. The zinc concentration in the slag was 0.1% or less. During the above process, the refined dust containing zinc components recovered by the dust collector is fed back to the hot metal pretreatment furnace seven times so that it can be finally recycled for the primary refinery industry with a zinc concentration of 62%. Material was obtained.
[0017]
[Example 3]
A scrap mass of 10 to 37 tons per charge was charged into a converter type hot metal pretreatment furnace. At this time, dust generated by the dust collecting and collecting apparatus is trapped in the bag filter. Subsequently, hot metal mass of 268 to 301 tons was charged per charge, while refining agent such as quick lime was added upwards while blowing from the bottom blowing tuyer with calcium carbonate, iron making dust and nitrogen gas, and oxygen gas was increased from the main lance. Blowing was performed for 420 to 660 seconds. After that, the blowing of oxygen gas was stopped, and the desulfurization treatment was performed for 300 seconds while blowing the flux in which CaO and Na 2 CO 3 were mixed at a mass ratio of 85:15 and the steelmaking dust collected by the bag filter. It was. The average blowing rate of CaCO 3 during desiliconization / dephosphorization described above is 1.6 kg / s, the flux blowing rate during desulfurization is 6.6 kg / s or more, and the dust blowing rate is The amount during the phosphorus treatment was 4.6 to 5.0 kg / s. The initial silicon, phosphorus, and sulfur mass concentrations of hot metal were 0.35 to 0.67%, 0.062 to 0.097%, and 0.01 to 0.02%, respectively. % Or less, 0.012 to 0.022%, 0.003 to 0.007%, 2 ppm or less, and the zinc mass concentration in the slag was 0.1% or less. Further, the steelmaking dust recovered by the bag filter was fed back to the hot metal pretreatment furnace seven times, and as a result, the ZnO mass concentration in the finally recovered steelmaking dust was 52%.
[0018]
【The invention's effect】
As is apparent from the above description, the present invention can produce a recyclable material for zinc primary refining industry having a high content of zinc component from zinc-containing scrap at a low running cost, and hot metal during refining. Because zinc does not remain inside, it is possible to eliminate the harmful effects caused by the zinc component being brought into the converter in the subsequent process, and furthermore, because it can be used without separating zinc-containing scrap and zinc-free scrap. The cost of sorting is also unnecessary. In addition, there is an advantage that it is only necessary to add a small amount of blowing equipment without adding new equipment costs and operating costs to the existing refining process.
Therefore, since the present invention can efficiently concentrate zinc from zinc-containing scrap to steelmaking dust, as a method for obtaining a recyclable material for the primary zinc refining industry, the contribution to industrial development is extremely large. .
[Brief description of the drawings]
FIG. 1 is a front view showing an embodiment of the present invention.
FIG. 2 is a front view showing another embodiment.
[Explanation of symbols]
1 Hot metal pretreatment furnace
2a Suction hood
2b Suction hood 3 Scrap chute 4 Lance 5 Blowing nozzle 6 Hopper
10 Zinc-containing scrap
11 Hot metal

Claims (1)

亜鉛含有スクラップを装入してある溶銑予備処理炉に溶銑を装入後、この溶銑予備処理炉に予め亜鉛含有スクラップを装入してある溶銑予備処理炉にて、亜鉛含有スクラップ中の金属亜鉛を加熱蒸発させ、その後に溶銑を装入して、溶銑予備処理炉から発生する亜鉛酸化物を含む製鋼ダストを回収して得られた亜鉛酸化物を含む製鋼ダストを、石灰石および/またはソーダ灰とともに吹込み、その上方から酸素を加えてこの溶銑予備処理炉から発生する高濃度化された亜鉛成分を含む製鋼ダストを回収することを特徴とする製鋼ダストの亜鉛濃縮方法。After the hot metal is charged into the hot metal pretreatment furnace in which the zinc-containing scrap is charged, in the hot metal pretreatment furnace in which the zinc-containing scrap is charged in advance, the metallic zinc in the zinc-containing scrap The steelmaking dust containing zinc oxide obtained by recovering the steelmaking dust containing zinc oxide generated from the hot metal pretreatment furnace by using hot metal after heating and evaporating, is converted into limestone and / or soda ash. A method for concentrating zinc in steelmaking dust, wherein the steelmaking dust containing high-concentration zinc components generated from the hot metal pretreatment furnace is recovered by blowing in and oxygen from above.
JP2000055625A 2000-03-01 2000-03-01 Zinc enrichment method for steelmaking dust Expired - Fee Related JP3825603B2 (en)

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