JP3848453B2 - Manufacturing method of metallic iron - Google Patents
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- JP3848453B2 JP3848453B2 JP00314598A JP314598A JP3848453B2 JP 3848453 B2 JP3848453 B2 JP 3848453B2 JP 00314598 A JP00314598 A JP 00314598A JP 314598 A JP314598 A JP 314598A JP 3848453 B2 JP3848453 B2 JP 3848453B2
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【０００１】
【発明の属する技術分野】
本発明は、鉄鉱石等の酸化鉄粉粒体を炭材とともに成形した炭材内装酸化鉄成形体を加熱還元して金属鉄を製造する技術に属し、さらに詳しくは、炭材内装酸化鉄成形体の還元過程において、酸化鉄や炭材とともに混入する脈石成分をスラグ化し、金属鉄とスラグとを溶融分離する金属鉄の製造技術に属するものである。
【０００２】
【従来の技術】
従来、還元鉄の製造方法としてはミドレックス法がよく知られており、この方法によれば天然ガスから変成した還元性ガスを羽口から吹き込み、シャフト炉中を上昇させることによって、炉内に充填された鉄鉱石や酸化鉄ペレットを還元して固体状態で還元鉄を得ることができる。ただし、この方法では燃料としてコストの高い天然ガスを大量に供給する必要がある。したがって、プラントの立地条件も天然ガスが発生する地域に限られる。
【０００３】
そこで近年では、上記天然ガスに替えて比較的安価な石炭を還元剤として使用することのできる還元鉄製造プロセスが注目されている。例えば、米国特許第3443931 号には、粉鉱石と炭材とを混合してペレット化し、高温雰囲気下で加熱還元することにより固体状態で還元鉄を製造するプロセスが開示されている。この方法によれば、石炭ベースであることの他にも、粉鉱石を直接使用できること、高速還元が可能であること、製品中の炭素含有量を調整することができる等の利点を有している。
【０００４】
しかし、従来の還元鉄の製造方法によって得られる還元鉄は、原料である鉄鉱石等の酸化鉄粉粒体や炭材に含まれる CaO、SiO2、Al2O3 の脈石成分がスラグとして混入してくるため、還元鉄の品位は低くなる。実用に当たっては、次の精錬工程でこのスラグは分離除去されるが、スラグ量の増加は精錬溶湯の歩留りを低下させるばかりでなく、電気炉の操業コストにも大きな影響を及ぼすので、鉄品位が高くスラグ含有量の少ない還元鉄が求められている。前述のように、従来の還元鉄の製造方法で、こうした要求に応えるには、原料に鉄品位の高い酸化鉄を使用しなければならず、使用可能な原料である酸化鉄の選択の幅を大幅に狭めることになる。
【０００５】
この解決策として、鉄品位の高い還元鉄を得るために、炭材内装酸化鉄成形体を加熱還元して金属鉄を製造する方法（平成８年特許願第５９８０１号）が提案されている。この方法は加熱還元により炭材内装酸化鉄成形体の表面に金属鉄外皮を生成し、この金属鉄外皮を成長させ、内部には酸化鉄が実質的に存在しなくなるまで還元を進めるとともに、内部に脈石成分からなる生成スラグを凝集させ、金属鉄とスラグとを溶融分離するものである。
【０００６】
【発明が解決しようとする課題】
この方法は、1400℃以上の還元温度で炭材内装酸化鉄成形体を還元し、この成形体の表面に金属鉄外皮を生成させ、さらに、この金属鉄外皮を成長させ、内部に脈石成分からなる生成スラグを凝集させ、金属鉄とスラグとを溶融分離するものである。ところが、脈石成分の組成によって生成スラグの融点が異なるため、金属鉄とスラグとを溶融分離するのに必要な時間がまちまちとなり、このため操業時間に大きなばらつきが生じる。したがって、高温の雰囲気温度を維持するために多量の燃料が必要となり、このことが操業コストを引き上げる原因になっている。
【０００７】
本発明は、上記の問題点を解決するためになされたもので、炭材内装酸化鉄成形体の原料に含まれる CaO、SiO2、Al2O3 の含有比率を調整することで、これらの脈石成分からなる生成スラグの融点をさげることにより、短時間で金属鉄とスラグとの溶融分離を行い品位の高い金属鉄を低い操業コストで得ることができる金属鉄の製造方法を提供することを目的とする。
【０００８】
その要旨は、炭材内装酸化鉄成形体を１４００℃以上の温度で加熱還元して金属鉄を製造する方法において、前記成形体の原料中の脈石成分である CaO、SiO2、Al2O3 の含有比率を調整することにより、これらの脈石成分からなる生成スラグの融点を１４００℃以下とし、前記成形体の表面に金属鉄外皮を生成させ、さらに、この金属鉄外皮を成長させて、その内部に上記脈石成分からなる生成スラグを溶融状態にして凝集させ、金属鉄とスラグとを溶融分離することを特徴とする金属鉄の製造方法である。
【０００９】
さらに、前記成形体の原料中の脈石成分であるCaO、SiO2、Al2O3 の含有比率を１種または２種以上の酸化鉄原料の配合によって、または生石灰等の含CaO 原料および／またはCaSiO3の配合によって調整する上記の金属鉄の製造方法である。
【００１０】
【発明の実施の形態】
本発明の重要な点は、炭材内装酸化鉄成形体の加熱還元過程において、原料に含まれる脈石成分である CaO、SiO2、Al2O3 の含有比率を調整することにより、これらの脈石成分からなる生成スラグの融点をさげ、短時間で金属鉄とスラグとを溶融分離することにある。このために、生成スラグの融点が1400℃以下になるように脈石成分である CaO、SiO2、Al2O3 の含有比率を調整する。
【００１１】
脈石成分である CaO、SiO2、Al2O3 の含有比率の調整は、酸化鉄原料である鉄鉱石の粉粒体、ミルスケール、高炉ダスト、転炉ダスト、焼結ダスト、電気炉ダストおよびこれらの混合物を組み合わせて配合することによって行う。すなわち、これらの酸化鉄原料は脈石成分である CaO、SiO2、Al2O3 の含有比率が異なるため、上記の酸化鉄原料を組み合わせて配合することで、脈石成分からなる生成スラグの融点を1400℃以下にするように、脈石成分である CaO、SiO2、Al2O3 の含有比率を調整することができる。また、配合原料に生石灰等の含CaO 原料および／またはCaSiO3を直接的に配合することによっても、脈石成分からなる生成スラグの融点を1400℃以下にするように、脈石成分である CaO、SiO2、Al2O3 の含有比率を調整することができる。
【００１２】
炭材内装酸化鉄成形体を1400℃以上の温度で加熱すると、この成形体中に含まれる炭材還元剤によって酸化鉄が還元されて金属鉄が生成するが、この還元は成形体の外周側から進行し、加熱還元の初期過程で生成する金属鉄が成形体の表面で拡散結合して上記成形体の外周側に金属鉄外皮を形成する。そして、その後この金属鉄外皮内で炭材還元剤による酸化鉄の還元が効率よく進行し、内部に残存する酸化鉄は、その後ごく短時間のうちに実質的に酸化鉄が存在しなくなるまで速やかに還元され、生成された金属鉄は前記外皮の内面側に逐次拡散結合して成長する。
【００１３】
一方、原料に含まれる脈石成分である CaO、SiO2、Al2O3 は、加熱還元過程でこれらの脈石成分からなる生成スラグの融点が、上述のように1400℃以下になるように調整してあるため、酸化鉄が金属鉄に還元される過程で上記生成スラグは溶融状態にあり、金属鉄と短時間で溶融分離し、上記金属鉄外皮内に溜まり外皮を構成する金属鉄と効率よく分離することができる。
【００１４】
この間に生じる加熱還元反応は下記に示す通りであり、
ＦｅＯx ＋ｘＣ→Ｆｅ＋ｘＣＯ （１）
ＦｅＯx ＋（ｘ／２）Ｃ→Ｆｅ＋（ｘ／２）ＣＯ2 （２）
Ｙ＝ｙ1 ＋ｙ2 （３）
但し、Ｙ：還元に必要な炭素の化学等量（ｍｏｌ）
ｙ1 ：（１）式の反応に必要な炭素量（ｍｏｌ）
ｙ2 ：（２）式の反応に必要な炭素量（ｍｏｌ）
成形体を製造する際の酸化鉄に対する炭材還元剤の配合量が、上記（３）式で示される理論等量以上となるように両者の配合比率を調整することによって、加熱還元反応を効率よく進めることが可能となる。
【００１５】
このように本発明では、加熱還元の初期過程で成形体外周側に金属鉄外皮を形成し、この外皮で囲まれた内部でさらに還元反応を進めることによって、還元効率を飛躍的に高めることができる。さらに好ましくは、加熱還元の最高到達温度を生成する金属鉄外皮の溶融温度未満で、かつ生成スラグの溶融温度以上に設定する。その理由は、最高到達温度が金属鉄外皮の溶融温度以上になると、還元される金属鉄は直ちに溶融して互いに融着し、前述のような金属鉄外皮が成形されなくなり、その後の還元反応が効率よく進行しなくなるからである。
【００１６】
その後、加熱還元の進行により還元剤である炭材の炭素が還元された金属鉄に浸炭し、金属鉄の融点がさがり、還元反応の末期ないしは後半期では、原料の一部は溶融し、液相還元により酸化鉄の最終還元が進行していることも考えられる。また、炭材からの浸炭により金属鉄の融点をさげ、金属鉄外皮の一部もしくは全部を溶融させて、溶融状態の生成スラグと溶融分離することによって、品位の高い金属鉄を得ることができる。
【００１７】
【実施例１】
表１に示す鉄鉱石、石炭（炭材）、バインダー（ベントナイト）、および脈石成分である CaO、SiO2、Al2O3 の含有比率を調整するCaSiO3試薬を表２に示す配合割合で混合し、直径17mmのペレット（炭材内装酸化鉄成形体）を製造した。なお、CaSiO3試薬の配合量は外挿で、このときの塩基度(CaO/SiO2)は、それぞれ0.05、0.26、0.40、0.49である。これらのペレットを炉内で1400℃の温度で加熱還元し、その時の還元・溶融挙動を観察した。なお、図１に生成スラグ（CaO-SiO2-Al2O3系スラグ）の組成とその融点との関係を示す。表３に加熱還元後の還元鉄の分析値とペレットの融け落ち時間を示す。また、図２にペレットの塩基度とペレットの融け落ち時間との関係を示す。ここでペレットの融け落ちとは、ペレットが元の形状を保つことができなくなり、全体が溶融しながら形状が変化することを言う。
【００１８】
表３に示すように、本発明による金属鉄の製造方法は、金属鉄と脈石成分からなる生成スラグとを溶融分離するため、金属鉄中に残存する脈石成分である CaO、SiO2、Al2O3 の量は極めて少ない。また、脈石成分の含有比率を調整しなくとも加熱還元過程で長時間を掛ければ、金属鉄と生成スラグとを溶融分離することはできるが、本発明のように、生成スラグの融点をさげることによって、炭材からの浸炭による金属鉄の融点の低下と相まって、金属鉄と生成スラグとの溶融分離が促進され、生成スラグの融点の低下とともにペレットの融け落ち時間も短縮されていることがわかる。
【００１９】
【表１】
【表２】
【表３】
【実施例２】
酸化鉄原料である鉄鉱石Ａ〜ＥおよびダストＡの化学成分を表４に示す。表４に示す酸化鉄原料72質量％、表１に示す石炭27質量％、表１に示すバインダー1.0 質量％を混合し、直径17mmのペレットを製造した。各酸化鉄原料の配合割合は、鉄鉱石Ａ:44.0 質量％、鉄鉱石Ｂ:9.0質量％、鉄鉱石Ｃ:10.0 質量％、鉄鉱石Ｄ:20.0 質量％、鉄鉱石Ｅ:10.0 質量％、ダストＡ:7.0質量％である。なお、原料の塩基度(CaO/SiO2)は0.40である。このペレットを炉内で1400℃の温度で加熱還元し、その時の還元・溶融挙動を観察した。表６に加熱還元後の還元鉄の分析値とペレットの融け落ち時間を示す。
【００２３】
脈石成分の異なる１種以上の酸化鉄原料を配合して、加熱還元過程で脈石成分からなる生成スラグの融点を1400℃以下になるように調整することによって、表６に示すように、ペレットの融け落ち時間を短縮することができる。このように、脈石成分の異なる酸化鉄原料を１種以上配合し、脈石成分の含有比率を調整して生成スラグの融点をさげることによって、炭材からの浸炭による金属鉄の融点の低下と相まって、金属鉄と生成スラグとの溶融分離が促進され、生成スラグの融点の低下とともにペレットの融け落ち時間も短縮されていることがわかる。また、金属鉄中に残存する脈石成分である CaO、SiO2、Al2O3 の量は極めて少ない。なお、表６の単一原料の例は、実施例１の表３に示すCaSiO3を配合しないときのものである。すなわち、表１に示した鉄鉱石のみを用いたペレットの加熱還元過程におけるもので、このときの塩基度(CaO/SiO2)は0.05である。
【００２４】
【表４】
【表５】
【表６】
【発明の効果】
以上述べたところから明らかなように、本発明によれば、炭材内装酸化鉄成形体の原料に含まれる CaO、SiO2、Al2O3 の含有比率を調整することで、これらの脈石成分からなる生成スラグの融点をさげているため、炭材からの浸炭による金属鉄の融点の低下と相まって、短時間で金属鉄とスラグとを溶融分離し、品位の高い金属鉄を低い操業コストで得ることができる。
【図面の簡単な説明】
【図１】生成スラグ（CaO-SiO2-Al2O3系スラグ）の組成とその融点との関係を示す図である。
【図２】ペレットの塩基度とペレットの融け落ち時間との関係を示す図である。[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to a technology for producing metallic iron by heating and reducing a carbonaceous iron-containing iron oxide molded body obtained by molding iron oxide particles such as iron ore together with a carbonaceous material, and more specifically, carbonaceous iron-containing iron oxide molding In the body reduction process, the gangue component mixed with iron oxide and carbonaceous material is converted into slag, and belongs to the manufacturing technology of metallic iron in which metallic iron and slag are melted and separated.
[0002]
[Prior art]
Conventionally, the Midrex method is well known as a method for producing reduced iron. According to this method, reducing gas transformed from natural gas is blown from the tuyere and raised in the shaft furnace to enter the furnace. Reduced iron can be obtained in a solid state by reducing the filled iron ore and iron oxide pellets. However, in this method, it is necessary to supply a large amount of high-cost natural gas as fuel. Therefore, the location conditions of the plant are also limited to areas where natural gas is generated.
[0003]
Therefore, in recent years, attention has been paid to a reduced iron production process in which relatively inexpensive coal can be used as a reducing agent instead of the natural gas. For example, U.S. Pat. No. 3,443,931 discloses a process for producing reduced iron in a solid state by mixing powdered ore and a carbonaceous material into pellets and heating and reducing in a high temperature atmosphere. According to this method, in addition to being based on coal, it has advantages such as being able to directly use fine ore, being capable of high-speed reduction, and being able to adjust the carbon content in the product. Yes.
[0004]
However, the reduced iron obtained by the conventional method for producing reduced iron is composed of iron oxide particles such as iron ore as raw materials and the gangue components of CaO, SiO 2 and Al 2 O 3 contained in the carbonaceous material as slag. Since it mixes, the quality of reduced iron will be low. In practical use, this slag is separated and removed in the next refining process, but an increase in the amount of slag not only lowers the yield of refining molten metal, but also greatly affects the operating cost of the electric furnace. There is a need for reduced iron with a high slag content. As described above, in order to meet these demands with the conventional method for producing reduced iron, it is necessary to use high-quality iron oxide as a raw material. It will be greatly narrowed.
[0005]
As a solution to this problem, a method of producing metallic iron by heating and reducing a carbonaceous material-containing iron oxide molded body has been proposed (1996 Patent Application No. 59801) in order to obtain reduced iron with high iron quality. This method generates a metallic iron skin on the surface of the carbonaceous iron-molded iron compact by heat reduction, grows this metallic iron skin, proceeds the reduction until there is virtually no iron oxide inside, and The slag formed from the gangue component is agglomerated to melt and separate metallic iron and slag.
[0006]
[Problems to be solved by the invention]
In this method, the carbonaceous iron oxide compact is reduced at a reduction temperature of 1400 ° C. or higher, and a metal iron skin is formed on the surface of the compact, and this metal iron skin is further grown. The produced slag consisting of the above is agglomerated to melt and separate metallic iron and slag. However, since the melting point of the generated slag differs depending on the composition of the gangue component, the time required to melt and separate the metallic iron and the slag varies, and thus the operating time varies greatly. Therefore, a large amount of fuel is required to maintain a high ambient temperature, which increases the operating cost.
[0007]
The present invention was made to solve the above problems, and by adjusting the content ratio of CaO, SiO 2 , Al 2 O 3 contained in the raw material of the carbonaceous material-containing iron oxide molded body, To provide a manufacturing method of metallic iron that can melt and separate metallic iron and slag in a short time to obtain high-quality metallic iron at a low operating cost by reducing the melting point of the generated slag composed of gangue components With the goal.
[0008]
The gist of the method is to produce metallic iron by heating and reducing a carbonaceous iron-containing molded body at a temperature of 1400 ° C. or higher. In this method, CaO, SiO 2 , Al 2 O which are gangue components in the raw material of the molded body By adjusting the content ratio of 3 , the melting point of the generated slag composed of these gangue components is set to 1400 ° C. or less, and a metallic iron skin is generated on the surface of the molded body, and further this metallic iron skin is grown. In the method for producing metallic iron, the produced slag composed of the gangue component is aggregated in the molten state, and the metallic iron and the slag are melted and separated.
[0009]
Furthermore, the content ratio of CaO, SiO 2 , Al 2 O 3 which is a gangue component in the raw material of the molded body is determined by blending one or two or more iron oxide raw materials, or a CaO raw material such as quick lime and / or or adjusted by blending of CaSiO 3 is a manufacturing method of the metallic iron.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The important point of the present invention is that by adjusting the content ratios of CaO, SiO 2 and Al 2 O 3 which are gangue components contained in the raw material in the heating and reducing process of the carbonaceous iron-containing iron oxide molded body, The purpose is to reduce the melting point of the slag formed from the gangue component and to melt and separate the metallic iron and slag in a short time. For this purpose, the content ratio of CaO, SiO 2 and Al 2 O 3 as gangue components is adjusted so that the melting point of the generated slag is 1400 ° C. or less.
[0011]
Adjustment of the content ratio of CaO, SiO 2 , Al 2 O 3 , which is a gangue component, is achieved by adjusting the iron ore powder, mill scale, blast furnace dust, converter dust, sintered dust, electric furnace dust And a mixture of these. That is, since these iron oxide raw materials have different content ratios of CaO, SiO 2 , and Al 2 O 3 , which are gangue components, by combining the above iron oxide raw materials, The content ratio of CaO, SiO 2 , and Al 2 O 3 that are gangue components can be adjusted so that the melting point is 1400 ° C. or lower. In addition, CaO, which is a gangue component, can be made less than 1400 ° C by directly blending CaO-containing raw materials such as quick lime and / or CaSiO 3 into the blended raw material so that the melting point of the formed slag composed of gangue components is 1400 ° C or less. , SiO 2 , Al 2 O 3 content ratio can be adjusted.
[0012]
When a carbonaceous material-containing iron oxide molded body is heated at a temperature of 1400 ° C or higher, iron oxide is reduced by the carbonaceous material reducing agent contained in the molded body to produce metallic iron. This reduction is performed on the outer peripheral side of the molded body. The metallic iron produced in the initial process of heat reduction is diffusion-bonded on the surface of the molded body to form a metallic iron skin on the outer peripheral side of the molded body. Then, the reduction of iron oxide by the carbonaceous material reducing agent proceeds efficiently within the metallic iron shell, and the iron oxide remaining in the interior is promptly until there is substantially no iron oxide in a very short time thereafter. The metallic iron produced by reduction is grown by sequential diffusion bonding on the inner surface side of the outer skin.
[0013]
On the other hand, CaO, SiO 2 and Al 2 O 3 which are gangue components contained in the raw materials are such that the melting point of the generated slag composed of these gangue components is 1400 ° C or less as described above. In the process where iron oxide is reduced to metallic iron, the generated slag is in a molten state, melted and separated from metallic iron in a short time, and accumulated in the metallic iron outer shell to form the outer metallic shell. It can be separated efficiently.
[0014]
The heat reduction reaction occurring during this time is as shown below.
FeOx + xC → Fe + xCO (1)
FeOx + (x / 2) C → Fe + (x / 2) CO 2 (2)
Y = y 1 + y 2 (3)
Y: chemical equivalent of carbon required for reduction (mol)
y 1 : Carbon amount required for the reaction of formula (1) (mol)
y 2 : Carbon amount required for the reaction of formula (2) (mol)
By adjusting the blending ratio of the two so that the blending amount of the carbonaceous material reducing agent with respect to the iron oxide at the time of manufacturing the molded body is equal to or more than the theoretical equivalent represented by the above formula (3), the heat reduction reaction is made efficient It is possible to proceed well.
[0015]
Thus, in the present invention, the reduction efficiency can be drastically improved by forming a metallic iron skin on the outer periphery of the molded body in the initial process of heat reduction and further proceeding the reduction reaction inside the outer skin. it can. More preferably, it is set to be lower than the melting temperature of the metallic iron shell that generates the highest temperature for heat reduction and higher than the melting temperature of the generated slag. The reason is that when the maximum temperature reaches or exceeds the melting temperature of the metallic iron shell, the metallic iron to be reduced immediately melts and fuses with each other, and the metallic iron shell as described above is not formed, and the subsequent reduction reaction is not performed. This is because it does not proceed efficiently.
[0016]
After that, the carbon of the carbon material, which is the reducing agent, is carburized into the reduced metallic iron as the heat reduction progresses, the melting point of the metallic iron decreases, and in the final or second half of the reduction reaction, a part of the raw material melts and becomes liquid It is also conceivable that the final reduction of iron oxide has progressed due to phase reduction. Also, high-quality metallic iron can be obtained by reducing the melting point of metallic iron by carburizing from the carbonaceous material, melting part or all of the metallic iron shell, and melting and separating from the molten slag. .
[0017]
[Example 1]
The composition ratio shown in Table 2 contains CaSiO 3 reagents that adjust the content ratios of iron ore, coal (charcoal), binder (bentonite), and gangue components CaO, SiO 2 , and Al 2 O 3 shown in Table 1. By mixing, pellets having a diameter of 17 mm (carbon material-containing iron oxide compacts) were produced. The compounding amount of the CaSiO 3 reagent is extrapolated, and the basicity (CaO / SiO 2 ) at this time is 0.05, 0.26, 0.40, and 0.49, respectively. These pellets were heated and reduced in a furnace at a temperature of 1400 ° C., and the reduction / melting behavior at that time was observed. FIG. 1 shows the relationship between the composition of the generated slag (CaO—SiO 2 —Al 2 O 3 slag) and its melting point. Table 3 shows the analytical value of reduced iron after heat reduction and the melting time of pellets. Further, FIG. 2 shows the relationship between the basicity of the pellet and the melting time of the pellet. Here, the pellet melt-off means that the pellet cannot maintain its original shape and the shape changes while the whole melts.
[0018]
As shown in Table 3, the method for producing metallic iron according to the present invention melts and separates metallic iron and the generated slag composed of gangue components, so that CaO, SiO 2 , which are gangue components remaining in metallic iron, The amount of Al 2 O 3 is extremely small. Further, if iron oxide and produced slag can be melted and separated by taking a long time in the heating reduction process without adjusting the content ratio of the gangue component, the melting point of produced slag is reduced as in the present invention. Therefore, coupled with a decrease in the melting point of metallic iron due to carburization from the carbon material, the melting separation of the metallic iron and the generated slag is promoted, and the melting time of the pellets is shortened as the melting point of the generated slag decreases. Recognize.
[0019]
[Table 1]
[Table 2]
[Table 3]
[Example 2]
Table 4 shows chemical components of iron ores A to E and dust A, which are iron oxide raw materials. 72 mass% of iron oxide raw materials shown in Table 4, 27 mass% of coal shown in Table 1, and 1.0 mass% of binder shown in Table 1 were mixed to produce pellets having a diameter of 17 mm. The mixing ratio of each iron oxide raw material is iron ore A: 44.0% by mass, iron ore B: 9.0% by mass, iron ore C: 10.0% by mass, iron ore D: 20.0% by mass, iron ore E: 10.0% by mass, dust A: 7.0% by mass. The basicity (CaO / SiO 2 ) of the raw material is 0.40. The pellets were heated and reduced in a furnace at a temperature of 1400 ° C., and the reduction / melting behavior at that time was observed. Table 6 shows the analytical value of reduced iron after heat reduction and the melting time of pellets.
[0023]
As shown in Table 6, by blending one or more iron oxide raw materials with different gangue components and adjusting the melting point of the slag formed from the gangue components to 1400 ° C or less during the heating and reduction process, It is possible to shorten the pellet melting time. Thus, by mixing one or more iron oxide raw materials having different gangue components and adjusting the content ratio of the gangue components to reduce the melting point of the generated slag, the melting point of metallic iron is reduced by carburizing from the carbonaceous material. In combination with the above, it can be seen that the melt separation between the metallic iron and the produced slag is promoted, and the melting time of the produced slag is reduced, and the melting time of the pellet is shortened. In addition, the amount of CaO, SiO 2 , and Al 2 O 3 that are gangue components remaining in metallic iron is extremely small. The example of a single material in Table 6 are those when no blending CaSiO 3 shown in Table 3 of Example 1. That is, in the heat reduction process of pellets using only iron ore shown in Table 1, the basicity (CaO / SiO 2 ) at this time is 0.05.
[0024]
[Table 4]
[Table 5]
[Table 6]
【The invention's effect】
As is clear from the above description, according to the present invention, these gangues are adjusted by adjusting the content ratio of CaO, SiO 2 , Al 2 O 3 contained in the raw material of the carbonaceous iron-containing iron oxide compact. Since the melting point of the generated slag consisting of components is reduced, coupled with a decrease in the melting point of metallic iron due to carburization from the carbonaceous material, the metallic iron and slag are melted and separated in a short time, and high-grade metallic iron is operated at low operating costs. Can be obtained at
[Brief description of the drawings]
FIG. 1 is a diagram showing the relationship between the composition of generated slag (CaO—SiO 2 —Al 2 O 3 -based slag) and its melting point.
FIG. 2 is a diagram showing the relationship between pellet basicity and pellet burn-off time.
Claims (3)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP00314598A JP3848453B2 (en) | 1998-01-09 | 1998-01-09 | Manufacturing method of metallic iron |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP00314598A JP3848453B2 (en) | 1998-01-09 | 1998-01-09 | Manufacturing method of metallic iron |
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| Publication Number | Publication Date |
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| JPH11199911A JPH11199911A (en) | 1999-07-27 |
| JP3848453B2 true JP3848453B2 (en) | 2006-11-22 |
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| JP4981320B2 (en) * | 2006-01-17 | 2012-07-18 | 株式会社神戸製鋼所 | Metal iron manufacturing method |
| JP2014159622A (en) * | 2013-02-20 | 2014-09-04 | Kobe Steel Ltd | Method of producing reduced iron |
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