JP5096811B2 - Manufacturing method of granular metallic iron - Google Patents

Manufacturing method of granular metallic iron Download PDF

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JP5096811B2
JP5096811B2 JP2007169628A JP2007169628A JP5096811B2 JP 5096811 B2 JP5096811 B2 JP 5096811B2 JP 2007169628 A JP2007169628 A JP 2007169628A JP 2007169628 A JP2007169628 A JP 2007169628A JP 5096811 B2 JP5096811 B2 JP 5096811B2
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slag
mgo
cao
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JP2009007620A (en
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高裕 工藤
一孝 國井
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Kobe Steel Ltd
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本発明は、粒状金属鉄の製造方法に関するものであり、より詳細には、酸化鉄含有物質と炭素質還元剤を含む原料混合物を移動炉床式加熱還元炉で加熱して直接還元し、粒状金属鉄を製造する方法に関するものである。   The present invention relates to a method for producing granular metallic iron, and more specifically, a raw material mixture containing an iron oxide-containing substance and a carbonaceous reducing agent is directly reduced by heating in a moving hearth type heating and reducing furnace. The present invention relates to a method for producing metallic iron.

鉄鉱石や酸化鉄等の酸化鉄含有物質から鉄を生産する方法としては、高炉法が主流である。その一方で、比較的小規模で、多品種・少量生産向きの製鉄法として、上記の酸化鉄含有物質と、石炭やコークス等の炭素質還元剤（以下、炭材ということがある）とを含む原料混合物（あるいは該混合物を押し固めた簡易成形体、更にはペレットやブリケットなどに成形した炭材内装成形体）を移動炉床式の加熱還元炉（例えば、回転炉床炉など）の炉床上に装入し、該原料混合物が該炉内を移動する間に、加熱バーナーによる熱や輻射熱で加熱することによって該原料混合物中の酸化鉄を炭素質還元剤で直接還元し、得られた金属鉄（還元鉄）を続いて浸炭・溶融させ、次いで副生するスラグと分離しつつ粒状に凝集させた後、冷却凝固させて粒状の金属鉄（還元鉄）を製造する直接還元製鉄法が開発され、注目を集めている（特許文献１〜３など）。   As a method for producing iron from iron oxide-containing substances such as iron ore and iron oxide, the blast furnace method is the mainstream. On the other hand, the iron oxide-containing material and carbonaceous reductants such as coal and coke (hereinafter sometimes referred to as carbon) are used as a relatively small-scale, high-mix, low-volume steelmaking method. Furnace of a moving hearth-type heating reduction furnace (for example, a rotary hearth furnace, etc.) containing a raw material mixture (or a simple molded body obtained by pressing and compacting the mixture, and further a carbonized material molded body formed into pellets or briquettes) The iron oxide in the raw material mixture was directly reduced with a carbonaceous reductant by heating on the floor and heating with heat or radiant heat from a heating burner while the raw material mixture moved through the furnace. A direct reduction iron manufacturing method in which metallic iron (reduced iron) is subsequently carburized and melted, then agglomerated in granular form while separating from by-product slag, and then cooled and solidified to produce granular metallic iron (reduced iron). Developed and attracting attention (patent literature) Such as to 3).

こうした直接還元製鉄法は、高炉等の大規模な設備が不要になるため、実用化するための研究が盛んに行われている。しかし工業的規模で実施するには、操業安定性や安全性、経済性、粒状金属鉄（製品）の品質などを含めて更に改善しなければならない課題も多い。   Since the direct reduction iron manufacturing method does not require large-scale facilities such as a blast furnace, research for practical application has been actively conducted. However, in order to implement on an industrial scale, there are many problems that must be further improved, including operational stability, safety, economy, and quality of granular metallic iron (product).

当該課題の１つは、炭素質還元剤として最も汎用性の高い石炭を使用した場合に、石炭中に多く含まれる硫黄分が粒状金属鉄に不可避的に混入するのを防止することが挙げられる。本発明者らが確認したところによると、炭素質還元剤として石炭を配合した原料混合物を加熱還元した場合、石炭に含まれる硫黄分のうち７０％程度以上は、加熱還元によって生成する粒状金属鉄内に取り込まれ、該粒状金属鉄中の硫黄量（以下、粒状金属鉄中の硫黄量を［Ｓ］、スラグ中の硫黄量を（Ｓ）と表わすことがある）は０．１％以上、用いる石炭の銘柄によっては０．２％以上にも達することがある。従ってこの様に高い硫黄含有量では製品価値が著しく損なわれ、用途も著しく制限されることになる。特に直接還元製鉄法によって得られた粒状金属鉄は、電気炉や転炉のような既存の製鋼設備へ送られ、鉄源としても使用されるため、粒状金属鉄中の硫黄量をできるだけ低減することが望まれる。   One of the problems is that, when the most versatile coal is used as the carbonaceous reducing agent, the sulfur content contained in the coal is prevented from being inevitably mixed in the granular metallic iron. . According to the present inventors, when a raw material mixture containing coal as a carbonaceous reducing agent is heated and reduced, about 70% or more of the sulfur content in the coal is granular metal iron produced by heating and reduction. The amount of sulfur in the granular metallic iron (hereinafter, the amount of sulfur in the granular metallic iron [S], the amount of sulfur in the slag may be represented as (S)) is 0.1% or more, Depending on the brand of coal used, it may reach 0.2% or more. Therefore, at such a high sulfur content, the product value is remarkably impaired and the use is remarkably limited. In particular, granular metal iron obtained by direct reduction ironmaking is sent to existing steelmaking facilities such as electric furnaces and converters, and is also used as an iron source, so the amount of sulfur in granular metal iron is reduced as much as possible. It is desirable.

そこで本発明者らは、上記方法によって得られる粒状金属鉄の硫黄含有量を可及的に低減するために改良研究を進めた。その結果、本発明者らは、金属鉄を溶融させたときに副生するスラグに含まれるＣａＯ量とＳｉＯ2量から求められる塩基度（ＣａＯ／ＳｉＯ2）を適切に制御すれば、粒状金属鉄の硫黄含有量を低減できることを見出し、特許文献４に記載の方法を提案した。 Therefore, the present inventors have advanced improvement studies to reduce the sulfur content of the granular metallic iron obtained by the above method as much as possible. As a result, if the present inventors appropriately control the basicity (CaO / SiO 2 ) obtained from the CaO amount and the SiO 2 amount contained in the slag produced as a by-product when the metallic iron is melted, the granular metal It discovered that the sulfur content of iron could be reduced and proposed the method of patent document 4. FIG.

特許文献４の方法を提案した後も、本発明者らは、更に研究を重ねてきた。その結果、スラグの塩基度［（ＣａＯ＋ＭｇＯ）／ＳｉＯ2］を１．３〜２．３の範囲とすると共に、スラグ中に占めるＭｇＯ量を５〜１３％の範囲に制御すれば、粒状金属鉄に含まれる硫黄量を低減でき、且つ、最終的に生成するスラグ−粒状金属鉄間の硫黄分配比（Ｓ）／［Ｓ］（以下、単に硫黄分配比ということがある。）を高められることを見出し、特許文献５に記載の方法を提案した。また、特許文献５には、上記のほかに、（ア）最終スラグの塩基度［（ＣａＯ＋ＭｇＯ）／ＳｉＯ2］が１．７以上になると、スラグの塩基度の上昇に伴って流動性が低下し、原料混合物中で酸化鉄含有物質が還元されることにより生成する還元鉄微粒子同士の凝集能が著しく低下すること、（イ）凝集能の低下により、粒径の大きい粒状金属鉄を安定して高歩留まりで製造できないこと、（ウ）歩留まりを高めるには、ＣａＦ2含有物質（例えば、蛍石）を添加すればよいことも記載されている。
特開平２−２２８４１１号公報 特開２００１−２７９３１３号公報 特開２００１−２４７９２０号公報 特開２００１−２７９３１５号公報 特開２００４−２８５３９９号公報 Even after proposing the method of Patent Document 4, the present inventors have further studied. As a result, when the basicity [(CaO + MgO) / SiO 2 ] of the slag is set in the range of 1.3 to 2.3 and the amount of MgO in the slag is controlled in the range of 5 to 13%, the granular metallic iron And the sulfur distribution ratio (S) / [S] (hereinafter sometimes simply referred to as sulfur distribution ratio) between the slag and the granular metallic iron to be finally produced can be increased. And proposed the method described in Patent Document 5. Further, in Patent Document 5, in addition to the above, when (a) the basicity [(CaO + MgO) / SiO 2 ] of the final slag is 1.7 or more, the fluidity decreases as the basicity of the slag increases. However, the agglomeration ability between the reduced iron fine particles produced by reducing the iron oxide-containing substance in the raw material mixture is remarkably reduced, and (a) the granular metal iron having a large particle size is stabilized by the reduction of the agglomeration ability. In addition, it is described that it cannot be manufactured at a high yield, and (c) a CaF 2 -containing substance (for example, fluorite) may be added to increase the yield.
JP-A-2-228411 JP 2001-279313 A JP 2001-247920 A JP 2001-279315 A JP 2004-285399 A

本発明は、この様な状況に鑑みてなされたものであり、その目的は、回転炉床式などの移動炉床式加熱還元炉を使用し、酸化鉄含有物質と炭素質還元剤を含む原料混合物を加熱し、該原料混合物中の酸化鉄含有物質を炭素質還元剤により直接還元して粒状金属鉄を製造する際に、石炭やコークスのように硫黄を多く含む炭素質還元剤を使用したときであっても、粒状金属鉄に混入する硫黄量を可及的に抑えることができ、硫黄含有量が低減された高品質の粒状金属鉄を歩留まりよく製造できる方法を提供することにある。   The present invention has been made in view of such a situation, and an object thereof is to use a moving hearth type heating reduction furnace such as a rotary hearth type, and a raw material containing an iron oxide-containing substance and a carbonaceous reducing agent. When the mixture is heated and the iron oxide-containing substance in the raw material mixture is directly reduced with a carbonaceous reducing agent to produce granular metallic iron, a carbonaceous reducing agent containing a large amount of sulfur such as coal or coke is used. Even if it is, it is providing the method which can suppress the amount of sulfur mixed in granular metallic iron as much as possible, and can manufacture high quality granular metallic iron with reduced sulfur content with high yield.

上記課題を解決することのできた本発明に係る低硫黄含有量の粒状金属鉄の製造方法とは、酸化鉄含有物質と炭素質還元剤を含む原料混合物を、移動炉床式加熱還元炉の炉床上に装入して加熱し、該原料混合物中の酸化鉄を炭素質還元剤により還元し、生成する金属鉄を副生するスラグと分離しつつ粒状に凝集させた後、冷却凝固させて粒状金属鉄を製造するにあたり、前記原料混合物に含まれるＣａＯ供給物質、ＭｇＯ供給物質およびＳｉＯ2供給物質の量を調整することによって、（１）スラグ中のＣａＯ、ＭｇＯおよびＳｉＯ2の含有量から求められる該スラグの塩基度［（ＣａＯ＋ＭｇＯ）／ＳｉＯ2］を１．５〜２．２の範囲とし、（２）該スラグ中のＭｇＯの含有量を１３％（質量％の意味。以下同じ）超、２５％以下とする点に要旨を有する。 The method for producing granular metallic iron having a low sulfur content according to the present invention, which has solved the above-mentioned problems, includes a raw material mixture containing an iron oxide-containing substance and a carbonaceous reducing agent, and a furnace of a moving hearth type heating reduction furnace. It is charged on the floor and heated, iron oxide in the raw material mixture is reduced with a carbonaceous reducing agent, and the resulting metallic iron is agglomerated into particles while being separated from slag as a by-product, and then cooled and solidified. In producing metallic iron, the amount of CaO supply material, MgO supply material and SiO 2 supply material contained in the raw material mixture is adjusted to obtain (1) the content of CaO, MgO and SiO 2 in the slag. The basicity [(CaO + MgO) / SiO 2 ] of the obtained slag is in the range of 1.5 to 2.2, and (2) the content of MgO in the slag exceeds 13% (meaning mass%, the same applies hereinafter) , 25% or less Has a gist.

上記原料混合物には、該原料混合物に含まれる前記ＭｇＯ供給物質以外のＭｇＯ供給物質、および／または前記原料混合物に含まれる前記ＣａＯ供給物質以外のＣａＯ供給物質を更に配合してもよい。   The raw material mixture may further contain an MgO supply material other than the MgO supply material contained in the raw material mixture and / or a CaO supply material other than the CaO supply material contained in the raw material mixture.

また、ＭｇＯおよびＣａＯの供給物質として、例えば、ドロマイト鉱石を配合してもよい。前記原料混合物に含まれる前記ＭｇＯ供給物質以外のＭｇＯ供給物質としては、例えば、ＭｇＯおよび／または炭酸マグネシウムを配合してもよい。前記原料混合物に含まれる前記ＣａＯ供給物質以外のＣａＯ供給物質としては、ＣａＯおよび／または炭酸カルシウムを配合してもよい。   Moreover, you may mix | blend a dolomite ore, for example as a supply substance of MgO and CaO. As the MgO supply substance other than the MgO supply substance contained in the raw material mixture, for example, MgO and / or magnesium carbonate may be blended. CaO and / or calcium carbonate may be blended as a CaO supply substance other than the CaO supply substance contained in the raw material mixture.

本発明には、上記製造方法で副生したスラグも包含される。このスラグは、例えば、（１）スラグ中のＣａＯ、ＭｇＯおよびＳｉＯ2の含有量から求められる該スラグの塩基度［（ＣａＯ＋ＭｇＯ）／ＳｉＯ2］が１．５〜２．２で、（２）該スラグ中のＭｇＯ含有量が１３％超、２５％以下になっている。 The present invention also includes slag by-produced by the above production method. This slag has, for example, (1) the basicity [(CaO + MgO) / SiO 2 ] of the slag determined from the contents of CaO, MgO and SiO 2 in the slag is 1.5 to 2.2, (2) The MgO content in the slag is more than 13% and 25% or less.

本発明によれば、粒状金属鉄に不可避的に混入する硫黄量の増大を可及的に抑えることができ、硫黄含有量の少ない高品質の粒状金属鉄を歩留まりよく製造することができる。   ADVANTAGE OF THE INVENTION According to this invention, the increase in the amount of sulfur inevitably mixed in granular metallic iron can be suppressed as much as possible, and high quality granular metallic iron with a small sulfur content can be manufactured with a sufficient yield.

本発明の還元鉄製造方法は、原料混合物中に含まれるＣａＯ供給物質、ＭｇＯ供給物質およびＳｉＯ2供給物質の量を調整し、（１）スラグ中のＣａＯ、ＭｇＯおよびＳｉＯ2の量から求められる該スラグの塩基度［（ＣａＯ＋ＭｇＯ）／ＳｉＯ2］を１．５〜２．２の範囲とし、（２）該スラグ中のＭｇＯ量を１３％超、２５％以下とすれば、硫黄含有量の少ない高品質の粒状金属鉄を歩留まり良く製造できることを見出したところに特徴がある。 The method for producing reduced iron of the present invention adjusts the amounts of CaO supply material, MgO supply material and SiO 2 supply material contained in the raw material mixture, and (1) is determined from the amounts of CaO, MgO and SiO 2 in the slag. If the basicity [(CaO + MgO) / SiO 2 ] of the slag is in the range of 1.5 to 2.2, and (2) the MgO content in the slag is more than 13% and 25% or less, the sulfur content It is characterized by finding that high-quality granular metallic iron can be produced with high yield.

以下、本発明に到達した経緯を説明する。   Hereinafter, the background to the present invention will be described.

本発明者らは、上記課題を達成するため、特に、前述した特許文献５に記載の技術、即ち、（ア）スラグの塩基度［（ＣａＯ＋ＭｇＯ）／ＳｉＯ2］の調整、および（イ）スラグのＭｇＯ量調整による還元鉄の硫黄量低減技術をベースにして検討を重ねてきた。特に、本発明では、環境対策を優先課題として掲げ、「蛍石無添加の原料混合物の使用が可能な直接還元製鉄法の提供」を重要視することにした。 In order to achieve the above-mentioned problems, the inventors of the present invention particularly described the technique described in Patent Document 5 mentioned above, that is, (a) adjusting the basicity [(CaO + MgO) / SiO 2 ] of slag, and (b) slag. Based on the technology for reducing the amount of sulfur in reduced iron by adjusting the amount of MgO, the study has been repeated. In particular, in the present invention, environmental measures are set as a priority issue, and “providing a direct reduction iron manufacturing method capable of using a raw material mixture containing no fluorite” has been emphasized.

その結果、「環境対策重視」の観点に基づけば、（ａ）スラグの塩基度は、特許文献５とほぼ同程度の範囲内に調整することを前提としつつも、（ｂ）スラグのＭｇＯ量の範囲は、特許文献５で定めた上限（１３％）を超えて２５％以下の範囲に拡大しても良く、これにより、電気炉用や転炉用の鉄源としても充分に使用可能な程度に硫黄量が低減された還元鉄を提供できることを見出し、本発明を完成した。   As a result, based on the viewpoint of “emphasis on environmental measures”, (a) the basicity of slag is assumed to be adjusted within the same range as in Patent Document 5, but (b) the amount of MgO in slag. The range of may exceed the upper limit (13%) defined in Patent Document 5 and expand to a range of 25% or less, and can be sufficiently used as an iron source for electric furnaces and converters. The present inventors have found that reduced iron having a reduced amount of sulfur can be provided to the extent that the present invention has been completed.

このように、前述した特許文献５も本発明も、いずれもスラグの塩基度およびスラグのＭｇＯ量を調整することによって還元鉄の硫黄量低減を図っている点で共通している。しかし、両者は、主に、課題との関係でＭｇＯ量の範囲が相違している。即ち、特許文献５では、「硫黄量の更なる低減化」を最優先課題として掲げ、特許文献５の目標レベル（硫黄分配比２５以上、金属鉄の硫黄量０．０５０％以下）との関係でスラグ中のＭｇＯ量の上限を１３％に定めた。これに対し、本発明では、環境対策を最優先課題として掲げ、特許文献５の目標レベルよりは低いが転炉用鉄源として充分使用可能な低硫黄量レベル（硫黄分配比１０以上、金属鉄の硫黄量０．０８０％以下）を達成し得る技術を提供するという観点から、ＭｇＯ量の上限を２５％に定めた。   Thus, both Patent Document 5 and the present invention described above are common in that the sulfur content of the reduced iron is reduced by adjusting the basicity of the slag and the MgO content of the slag. However, both are different in the range of the amount of MgO mainly due to the problem. That is, in Patent Document 5, “further reduction in the amount of sulfur” is given as the highest priority, and the relationship with the target level of Patent Document 5 (a sulfur distribution ratio of 25 or more and a sulfur content of metallic iron of 0.050% or less). Thus, the upper limit of the amount of MgO in the slag was set to 13%. On the other hand, in the present invention, environmental measures are given the highest priority, and a low sulfur amount level (sulphur distribution ratio of 10 or more, metallic iron, which is lower than the target level of Patent Document 5 but can be sufficiently used as an iron source for a converter. From the viewpoint of providing a technology capable of achieving a sulfur content of 0.080% or less), the upper limit of the MgO content is set to 25%.

例えば、「蛍石の不使用」という観点に基づけば、特許文献５では、「スラグの塩基度≧１．７の範囲では蛍石の添加を推奨しており、これにより、還元鉄微粒子同士の凝集能の著しい低下を防止でき、歩留まりが高められることが記載されている。これに対し、本発明によれば、スラグの塩基度が１．５〜２．２の範囲内であれば、蛍石を使用しなくても、低硫黄量の還元鉄を歩留まり良く製造できる（後記する実施例を参照）。なお、本明細書において、「スラグの塩基度」とは、特に断らない限り、スラグ中のＣａＯ、ＭｇＯおよびＳｉＯ2の含有量から求められる（ＣａＯ＋ＭｇＯ）／ＳｉＯ2の比を意味する。 For example, based on the viewpoint of “non-use of fluorite”, Patent Document 5 recommends the addition of fluorite within the range of “basicity of slag ≧ 1.7, thereby According to the present invention, it is possible to prevent a significant decrease in the coagulation ability and increase the yield, whereas according to the present invention, if the basicity of the slag is in the range of 1.5 to 2.2, Low-sulfur reduced iron can be produced with good yield without using stone (see Examples below) In this specification, “basicity of slag” means slag unless otherwise specified. It means the ratio of (CaO + MgO) / SiO 2 determined from the contents of CaO, MgO and SiO 2 therein.

［（１）スラグの塩基度［（ＣａＯ＋ＭｇＯ）／ＳｉＯ2］：１．５〜２．２］
本発明における「スラグの塩基度」の意義は、前述した特許文献５と実質的に同じである。即ち、スラグの塩基度は、粒状金属鉄の歩留まり向上、粒状金属鉄に不可避的に混入する硫黄量［Ｓ］の低減化に寄与するパラメータであるため、その下限を１．５とした。スラグの塩基度が１．５を下回ると、スラグそのものによる脱硫能が低下してしまう。本発明を実施する上で好ましいスラグの塩基度は、１．６以上である。但し、スラグの塩基度が高くなると、スラグの粘性（流動性）が増大して還元鉄の凝集が阻害され、球形に近い好適形状の粒状金属鉄が得られ難くなるほか、粒状金属鉄の歩留りが逆に低下する傾向が見られるので、スラグの塩基度の上限を２．２とした。スラグの塩基度は、好ましくは２．１以下、より好ましくは２．０以下に調整するのがよい。 [(1) Basicity of slag [(CaO + MgO) / SiO 2 ]: 1.5 to 2.2]
The meaning of “basicity of slag” in the present invention is substantially the same as that of Patent Document 5 described above. That is, the basicity of the slag is a parameter that contributes to improving the yield of granular metallic iron and reducing the amount of sulfur [S] inevitably mixed in the granular metallic iron, so the lower limit was set to 1.5. When the basicity of slag is less than 1.5, the desulfurization ability by slag itself will fall. In practicing the present invention, the basicity of slag that is preferable is 1.6 or more. However, when the basicity of the slag increases, the viscosity (fluidity) of the slag increases and the reduced iron agglomeration is hindered, making it difficult to obtain a granular metal iron having a suitable shape close to a sphere, and the yield of the granular metal iron. On the contrary, since the tendency to decrease is seen, the upper limit of the basicity of slag was set to 2.2. The basicity of the slag is preferably adjusted to 2.1 or less, more preferably 2.0 or less.

［（２）スラグ中のＭｇＯ量：１３％超、２５％以下］
本発明における「スラグ中のＭｇＯ量」の意義は、前述した特許文献５と実質的に同じであり、良好な硫黄分配比（Ｓ）／［Ｓ］を得るために設定されたものである。但し、前述した特許文献５では、「硫黄量の極低減化」を最優先課題として掲げ、２５以上の硫黄分配比を確保するという観点から、ＭｇＯ量の上限を１３％に定めていたのに対し、本発明では、特許文献５の目標レベルよりは低いが転炉用鉄源として充分使用可能な低硫黄量レベル（１０以上の硫黄分配比の確保、金属鉄の硫黄量０．０８０％以下）を実現するという観点から、ＭｇＯ量の下限を１３％超とし、上限を２５％とした。本発明によれば、蛍石を使用しなくても、本発明の目標レベルを確実に実現することができる。硫黄量の更なる低減化という観点からすれば、ＭｇＯ量は少ない方がよく、ＭｇＯ量の好ましい上限は２０％である。 [(2) MgO content in slag: more than 13%, 25% or less]
The significance of “MgO amount in slag” in the present invention is substantially the same as that of Patent Document 5 described above, and is set to obtain a good sulfur distribution ratio (S) / [S]. However, in the above-mentioned Patent Document 5, “extremely reducing the amount of sulfur” is set as the highest priority, and the upper limit of the MgO amount is set to 13% from the viewpoint of securing a sulfur distribution ratio of 25 or more. On the other hand, in the present invention, a low sulfur level that is lower than the target level of Patent Document 5 but can be sufficiently used as an iron source for a converter (ensuring a sulfur distribution ratio of 10 or more, sulfur content of metallic iron is 0.080% or less) ), The lower limit of the MgO amount is set to more than 13% and the upper limit is set to 25%. According to the present invention, the target level of the present invention can be reliably realized without using fluorite. From the viewpoint of further reducing the amount of sulfur, it is better that the amount of MgO is small, and a preferable upper limit of the amount of MgO is 20%.

生成スラグが上記（１）〜（２）を満足するように原料の成分調整を行うことで、副生するスラグの融点を、おおむね、１３５０〜１５５０℃とすることができ、移動炉床式加熱還元炉を操業するときの一般的な温度である１５５０℃程度よりも低くすることができる。そのため生成スラグが上記要件を満足するように原料の成分調整を行った原料混合物を移動炉床式加熱還元炉内で加熱すると、スラグ形成成分が速やかに溶解し、これが凝集してスラグが素早く形成されるようになる。スラグが素早く形成されると、残った金属鉄は粒状に凝集し易くなるため、結果として、粒状金属鉄の歩留まりが向上するのである。   By adjusting the ingredients of the raw material so that the generated slag satisfies the above (1) to (2), the melting point of the by-product slag can be set to about 1350 to 1550 ° C. It can be made lower than about 1550 ° C., which is a typical temperature when operating the reduction furnace. For this reason, when the raw material mixture is adjusted so that the generated slag satisfies the above requirements, the raw material mixture is heated in a moving hearth type heating and reducing furnace, and the slag-forming components are rapidly dissolved and aggregated to form slag quickly. Will come to be. When the slag is formed quickly, the remaining metallic iron is likely to aggregate in a granular form, and as a result, the yield of the granular metallic iron is improved.

また、生成スラグが上記（１）〜（２）を満足するように原料の成分調整を行うことで、最終的に生成するスラグ−粒状金属鉄間の硫黄分配比（Ｓ）／［Ｓ］が著しく向上し、粒状金属鉄中に歩留る硫黄含有量［Ｓ］を大幅に低減できる。   Moreover, the sulfur distribution ratio (S) / [S] between the slag and granular metal iron finally produced | generated by adjusting the component of a raw material so that production | generation slag may satisfy said (1)-(2). The sulfur content [S] that is significantly improved and is retained in the granular metallic iron can be greatly reduced.

副生するスラグの融点を１３５０〜１５５０℃程度に調整するには、上記（１）〜（２）を満足するように原料の成分調整を行えばよいが、スラグに含まれるＣａＯ量やＡｌ2Ｏ3量、ＳｉＯ2量等も併せて調整することが推奨できる。スラグの融点は、これらの酸化物の量にも多少影響を受けるからである。ＣａＯ量は３０〜５０％程度、Ａｌ2Ｏ3量は２０％未満、ＳｉＯ2量は４０％未満に調整すればよい。 In order to adjust the melting point of the slag produced as a by-product to about 1350 to 1550 ° C., the raw material components may be adjusted so as to satisfy the above (1) to (2), but the amount of CaO contained in the slag and Al 2 It is recommended to adjust the amount of O 3, the amount of SiO 2 and the like together. This is because the melting point of slag is somewhat affected by the amount of these oxides. The amount of CaO may be adjusted to about 30 to 50%, the amount of Al 2 O 3 may be adjusted to less than 20%, and the amount of SiO 2 may be adjusted to less than 40%.

上述した（１）スラグの塩基度と（２）スラグ中のＭｇＯ量は、原料である酸化鉄含有物質と炭素質還元剤の配合量を適切に調整することによって制御できる。酸化鉄含有物質や炭素質還元剤は、通常、ＣａＯ、ＭｇＯおよびＳｉＯ2の脈石成分を含んでいるため、ＣａＯ供給物質、ＭｇＯ供給物質およびＳｉＯ2供給物質となるからである。なお、酸化鉄含有物質の代表例である鉄鉱石や、炭素質還元剤の代表例である石炭やコークスは天然物であり、種類に応じてＣａＯやＭｇＯ、ＳｉＯ2の各含有量も変化するため、それらの配合量を一律に規定することは困難であるが、鉄鉱石等の成分組成と、石炭等の成分組成を考慮し、適切に調整することが好ましい。また、炭素質粉末を床敷材として装入する場合は、該炭素質粉末の成分とその量も考慮して、酸化鉄含有物質と炭素質還元剤の配合量を調整することによって、上記スラグの塩基度や該スラグに占めるＭｇＯ量を制御すればよい。 The basicity of (1) slag and (2) the amount of MgO in the slag can be controlled by appropriately adjusting the blending amounts of the raw material containing iron oxide and the carbonaceous reducing agent. This is because the iron oxide-containing material and the carbonaceous reducing agent usually contain CaO, MgO, and SiO 2 gangue components, and thus become a CaO supply material, a MgO supply material, and a SiO 2 supply material. In addition, iron ore, which is a typical example of an iron oxide-containing substance, and coal and coke, which are typical examples of a carbonaceous reducing agent, are natural products, and the contents of CaO, MgO, and SiO 2 vary depending on the type. Therefore, it is difficult to uniformly define the blending amounts thereof, but it is preferable to appropriately adjust in consideration of the component composition such as iron ore and the component composition such as coal. In addition, when the carbonaceous powder is charged as a flooring material, the amount of the iron oxide-containing substance and the carbonaceous reducing agent is adjusted in consideration of the components and the amount of the carbonaceous powder. The basicity of Mg and the amount of MgO in the slag may be controlled.

本発明に用いられる原料混合物は、前述した酸化鉄含有物質および炭素質還元剤のほかに、これら以外の「他のＭｇＯ供給物質」（酸化鉄含有物質および炭素質還元剤から見れば、外添物質）を含んでいてもよい。この場合は、当該「他のＭｇＯ供給物質」の成分組成とその配合量も考慮して酸化物含有物質と炭素質還元剤の量を調整することによって、最終的に、上記スラグの塩基度や該スラグに占めるＭｇＯ量を制御する。   In addition to the iron oxide-containing substance and the carbonaceous reducing agent described above, the raw material mixture used in the present invention includes other “other MgO supply substances” (from the viewpoint of the iron oxide-containing substance and the carbonaceous reducing agent, the external additive Substance). In this case, by adjusting the amount of the oxide-containing substance and the carbonaceous reducing agent in consideration of the component composition of the “other MgO supply substance” and its blending amount, finally, the basicity of the slag and The amount of MgO in the slag is controlled.

上記「他のＭｇＯ供給物質」の種類は特に制限されないが、例えば、ＭｇＯ粉末や天然鉱石や海水などから抽出されるＭｇ含有物質、或いは炭酸マグネシウム（ＭｇＣＯ3）などが挙げられる。 The type of the “other MgO supply substance” is not particularly limited, and examples thereof include an Mg-containing substance extracted from MgO powder, natural ore, seawater, or magnesium carbonate (MgCO 3 ).

また、本発明に用いられる原料混合物は、前述した酸化鉄含有物質および炭素質還元剤のほかに、これら以外の「他のＣａＯ供給物質」（酸化鉄含有物質および炭素質還元剤から見れば、外添物質）を含んでいてもよい。この場合は、当該「他のＣａＯ供給物質」の成分組成とその配合量も考慮して酸化物含有物質と炭素質還元剤の量を調整することによって、最終的に、上記スラグの塩基度や該スラグに占めるＣａＯ量を制御する。   In addition to the iron oxide-containing substance and the carbonaceous reducing agent described above, the raw material mixture used in the present invention, in addition to these, “other CaO supply substances” (from the viewpoint of the iron oxide-containing substance and the carbonaceous reducing agent, (External additive substance) may be included. In this case, by adjusting the amount of the oxide-containing substance and the carbonaceous reducing agent in consideration of the component composition of the “other CaO supply substance” and the blending amount thereof, finally, the basicity of the slag or The amount of CaO in the slag is controlled.

上記「他のＣａＯ供給物質」の種類は特に制限されないが、代表例として生石灰（ＣａＯ）や炭酸カルシウム（ＣａＣＯ3）などが挙げられる。 The type of the “other CaO supply substance” is not particularly limited, but representative examples include quick lime (CaO) and calcium carbonate (CaCO 3 ).

また、「他のＭｇＯ供給物質」でもあり、且つ「他のＣａＯ供給物質」でもある例として、例えば、ドロマイト鉱石を配合してもよい。   In addition, as an example of being “another MgO supply substance” and “another CaO supply substance”, for example, dolomite ore may be blended.

なお、「環境対策重視」の観点に基づけば、原料混合物に蛍石は配合しないことが望まれ、上述した本発明によれば、蛍石を配合しなくとも充分に脱硫能と凝集性能の向上が図れる。しかし原料混合物に蛍石を配合して脱硫能および凝集性能の一層の向上を図ることもできる。   From the viewpoint of “emphasis on environmental measures”, it is desirable not to add fluorite to the raw material mixture, and according to the present invention described above, sufficient desulfurization ability and agglomeration performance can be improved without adding fluorite. Can be planned. However, it is also possible to further improve desulfurization ability and agglomeration performance by blending fluorite with the raw material mixture.

次に、図１を参照しながら、本発明に係る移動炉床式加熱還元炉を用いた粒状金属鉄の製造方法を詳細に説明する。図１は、本発明の製造方法に好ましく用いられる移動炉床式加熱還元炉の一例であり、これに限定する趣旨ではない。   Next, a method for producing granular metallic iron using the moving hearth-type heat reduction furnace according to the present invention will be described in detail with reference to FIG. FIG. 1 is an example of a moving hearth type heat reduction furnace preferably used in the production method of the present invention, and is not intended to be limited thereto.

図１は、移動炉床式加熱還元炉のうち、回転炉床式の加熱還元炉Ａの一構成例を示す概略説明図である。なお、炉の内部構造を示すために、炉の一部を切り欠き、内部を示している。   FIG. 1 is a schematic explanatory diagram showing a configuration example of a rotary hearth-type heating reduction furnace A among moving hearth-type heating reduction furnaces. In addition, in order to show the internal structure of a furnace, a part of furnace is notched and the inside is shown.

回転炉床式の加熱還元炉Ａには、酸化鉄含有物質と炭素質還元剤を含む原料混合物１が、原料投入ホッパー３を通して、回転炉床４上へ連続的に装入される。酸化鉄含有物質としては、通常、鉄鉱石やマグネタイト鉱石などが用いられる。また、炭素質還元剤としては、通常、石炭やコークスなどが用いられる。   In the rotary hearth type heating reduction furnace A, the raw material mixture 1 containing the iron oxide-containing substance and the carbonaceous reducing agent is continuously charged onto the rotary hearth 4 through the raw material charging hopper 3. As the iron oxide-containing substance, iron ore and magnetite ore are usually used. Moreover, as a carbonaceous reducing agent, coal, coke, etc. are normally used.

前記原料混合物１を供給するときの形態は特に限定されず、酸化鉄含有物質と炭素質還元剤などを適度に混合したものを供給すればよい。特に、酸化鉄含有物質と炭素質還元剤などを含む原料混合物を押し固めて得られた簡易成形体を供給するか、または該原料混合物をペレットやブリケットなどに成形した炭材内装成形体を供給するのがよい。また、前記簡易成形体や前記炭材内装成形体と併せて、粉粒状の炭素質粉末２を供給してもよい。   The form at the time of supplying the said raw material mixture 1 is not specifically limited, What is necessary is just to supply what mixed an iron oxide containing substance, a carbonaceous reducing agent, etc. moderately. In particular, supply a simple molded body obtained by pressing and solidifying a raw material mixture containing an iron oxide-containing substance and a carbonaceous reducing agent, or a carbonaceous interior molded body obtained by molding the raw material mixture into pellets or briquettes. It is good to do. Moreover, you may supply the granular carbonaceous powder 2 with the said simple molded object and the said carbonaceous material interior molded object.

本発明法では、必要に応じて、上記原料混合物以外の物質（例えば、ＭｇＯ供給物質やＣａＯ供給物質など）を装入してもよい。   In the method of the present invention, if necessary, substances other than the raw material mixture (for example, MgO supply substance, CaO supply substance, etc.) may be charged.

次に、上記原料混合物１を加熱還元炉Ａに装入するときの手順を具体的に説明する。前記原料混合物１の装入に先立って、原料投入ホッパー３から回転炉床４上に粉粒状の炭素質粉末２を床敷として装入して敷き詰めておき、その上に前記原料混合物１を装入するのがよい。   Next, a procedure for charging the raw material mixture 1 into the heating reduction furnace A will be specifically described. Prior to the charging of the raw material mixture 1, the granular carbonaceous powder 2 is charged and spread on the rotary hearth 4 from the raw material charging hopper 3, and the raw material mixture 1 is loaded thereon. It is good to enter.

上記酸化鉄含有物質と炭素質還元剤以外に配合され得るＭｇＯ供給物質やＣａＯ供給物質の添加法にも格別の制限はなく、原料混合物の調整段階で配合したり、床敷材と共に、或いはこれとは独立に回転炉床上へ予め装入しておき、或いは原料混合物の装入と同時もしくは後に上方から別途装入する方法、等を適宜採用できる。   There is no particular limitation on the method of adding the MgO supply material and CaO supply material that can be blended in addition to the iron oxide-containing material and the carbonaceous reducing agent, and it can be blended at the stage of adjusting the raw material mixture, with the floor covering material, Independently, it is possible to adopt a method of charging in advance on the rotary hearth, or separately charging from above at the same time as or after charging the raw material mixture.

原料混合物には、バインダーとして少量の多糖類（例えば、小麦粉等の澱粉）を配合してもよい。   You may mix | blend a small amount of polysaccharides (for example, starch, such as wheat flour) as a binder with a raw material mixture.

図１に示した例では、１つの原料投入ホッパー３を炭素質粉末２の装入と、上記原料混合物１を装入するために共用する例を示しているが、ホッパーを２つ以上用いて炭素質粉末２と上記原料混合物１を別々に装入することも勿論可能である。   In the example shown in FIG. 1, an example in which one raw material charging hopper 3 is shared for charging the carbonaceous powder 2 and charging the raw material mixture 1 is shown. However, two or more hoppers are used. Of course, it is possible to charge the carbonaceous powder 2 and the raw material mixture 1 separately.

なお、床敷材として炉床上に装入される炭素質粉末の使用は必ずしも必須ではなく、装入を省略してもよいが、炉床上に炭素質粉末を床敷材として装入すれば、炉内の還元ポテンシャルがより効率的に高められ、金属化率の向上と硫黄含有量の低減の両作用をより一層効果的に発揮させることができるので好ましい。こうした床敷材としての作用をより確実に発揮させるには、炉床上へ２ｍｍ程度以上の厚みで粉粒状の炭素質粉末を敷いておくことが望ましい。しかも炭素質粉末を床敷材としてある程度の厚みを持った層状に敷き詰めておけば、該床敷層が原料混合物と炉床耐火物の緩衝材となり、或いは副生スラグ等に対する炉床耐火物の保護材となり、炉床耐火物の寿命延長にも役立つ。   In addition, the use of carbonaceous powder charged on the hearth as a flooring material is not necessarily required and charging may be omitted, but if carbonaceous powder is charged on the hearth as a flooring material, This is preferable because the reduction potential in the furnace can be increased more efficiently, and the effects of improving the metallization rate and reducing the sulfur content can be exhibited more effectively. In order to exhibit such an action as a floor covering more reliably, it is desirable to lay a granular carbonaceous powder on the hearth with a thickness of about 2 mm or more. Moreover, if carbonaceous powder is spread in a layer with a certain thickness as a flooring material, the flooring layer becomes a buffer material for the raw material mixture and hearth refractory, or the hearth refractory for by-product slag, etc. It becomes a protective material and helps to extend the life of hearth refractories.

但し、床敷層が厚くなり過ぎると、原料混合物が炉床上の床敷層内へ潜り込んで還元の進行が阻害される等の問題を生じることがあるので、床敷層の厚みは、７．５ｍｍ程度以下に抑えることが望ましい。   However, if the flooring layer becomes too thick, the raw material mixture may sink into the flooring layer on the hearth and prevent the progress of reduction, and therefore the thickness of the flooring layer is 7. It is desirable to suppress it to about 5 mm or less.

上記床敷材として用いる炭素質粉末の種類は特に限定されず、通常の石炭やコークス等を粉砕し、好ましくは適度に粒度調整したものを使用すればよく、また石炭を使用する場合は、流動性が低く且つ炉床上で膨れや粘着性を帯びることのない無煙炭が好適である。床敷として装入する炭素質粉末は、上記原料混合物１に配合されている炭素質還元剤よりも硫黄含有分が少ないものを用いるのがよい。   The type of carbonaceous powder used as the flooring material is not particularly limited, and normal coal or coke or the like is pulverized, preferably with a moderately adjusted particle size, and when using coal, Anthracite which has low property and does not bulge or stick on the hearth is preferred. As the carbonaceous powder charged as a flooring, it is preferable to use a carbonaceous powder having a lower sulfur content than the carbonaceous reducing agent blended in the raw material mixture 1.

図１に示した加熱還元炉Ａの回転炉床４は、反時計方向に回転されている。回転炉床４の回転速度は、加熱還元炉Ａの大きさや操業条件によって異なるが、通常は８分から１６分程度で１周する速度である。加熱還元炉Ａにおける炉体８の壁面には加熱バーナー５が複数個設けられており、該加熱バーナー５の燃焼熱あるいはその輻射熱によって炉床部に熱が供給される。加熱バーナー５は、炉の天井部に設けてもよい。   The rotary hearth 4 of the heating reduction furnace A shown in FIG. 1 is rotated counterclockwise. The rotational speed of the rotary hearth 4 varies depending on the size and operating conditions of the heating reduction furnace A, but is usually a speed that makes one turn in about 8 to 16 minutes. A plurality of heating burners 5 are provided on the wall surface of the furnace body 8 in the heating and reducing furnace A, and heat is supplied to the hearth by the combustion heat of the heating burner 5 or its radiant heat. The heating burner 5 may be provided on the ceiling of the furnace.

耐火材で構成された回転炉床４上に装入された上記原料混合物１は、該回転炉床４上で加熱還元炉Ａ内を周方向へ移動する中で、加熱バーナー５からの燃焼熱や輻射熱によって加熱される。そして当該加熱還元炉Ａ内の加熱帯を通過する間に、当該原料混合物１内の酸化鉄は還元された後、副生する溶融スラグと分離しながら、且つ残余の炭素質還元剤による浸炭を受けて溶融しながら粒状に凝集して粒状金属鉄１０となり、回転炉床４の下流側ゾーンで冷却固化された後、スクリューなどの排出装置６によって炉床上から順次排出される。このとき副生したスラグも排出されるが、これらはホッパー９を経た後、任意の分離手段（例えば、篩目や磁選装置など）により金属鉄とスラグの分離が行われる。なお、図１中、７は排ガス用ダクトを示している。   The raw material mixture 1 charged on the rotary hearth 4 made of refractory material moves in the heating reduction furnace A on the rotary hearth 4 in the circumferential direction, and the combustion heat from the heating burner 5 Or heated by radiant heat. And while passing through the heating zone in the heating and reducing furnace A, the iron oxide in the raw material mixture 1 is reduced and then separated from the by-product molten slag and carburized by the remaining carbonaceous reducing agent. The molten metal aggregates into granular metallic iron 10 while being melted and is cooled and solidified in the downstream zone of the rotary hearth 4, and then sequentially discharged from the hearth by a discharge device 6 such as a screw. At this time, slag produced as a by-product is also discharged, but after passing through the hopper 9, the metal iron and the slag are separated by an arbitrary separating means (for example, a sieve or a magnetic separator). In FIG. 1, reference numeral 7 denotes an exhaust gas duct.

以上の通り、本発明では、加熱還元して副生する（１）スラグの塩基度と、（２）スラグ中のＭｇＯ量を適切に調整し、生成スラグの融点と硫黄分配比（Ｓ）／［Ｓ］をうまくコントロールすることによって、低硫黄含有量の粒状金属鉄を効率よく確実に製造することが可能となる。   As described above, in the present invention, (1) the basicity of slag produced by heat reduction and (2) the amount of MgO in the slag is appropriately adjusted, and the melting point and sulfur distribution ratio (S) / By controlling [S] well, it becomes possible to efficiently and reliably produce granular metallic iron having a low sulfur content.

以下、本発明を実施例によって更に詳細に説明するが、下記実施例は本発明を限定する性質のものではなく、前・後記の趣旨に適合し得る範囲で適当に変更して実施することも可能であり、それらはいずれも本発明の技術的範囲に含まれる。なお、下記実施例では、小型の実験用加熱還元炉を用いて試験を行った結果を示す。   Hereinafter, the present invention will be described in more detail with reference to examples. However, the following examples are not intended to limit the present invention, and may be implemented with appropriate modifications within a range that can meet the purpose described above and below. These are all possible and are within the scope of the present invention. The following examples show the results of tests using a small experimental heating and reducing furnace.

酸化鉄含有物質として鉄鉱石を用い、炭素質還元剤として石炭を用い、これらを混合して原料混合物を得た。鉄鉱石の成分組成を下記表１に、石炭の成分組成を下記表２に示す。但し、表２において、「その他」とは固形炭素質を意味する。   Iron ore was used as the iron oxide-containing substance, coal was used as the carbonaceous reducing agent, and these were mixed to obtain a raw material mixture. The component composition of iron ore is shown in Table 1 below, and the component composition of coal is shown in Table 2 below. However, in Table 2, “others” means solid carbonaceous matter.

上記原料混合物には、酸化鉄含有物質と炭素質還元剤の他にバインダーを配合し、必要に応じて、スラグ塩基度調整用副原料を配合して配合物を得た。上記バインダーとしては、小麦粉を配合した。   In addition to the iron oxide-containing substance and the carbonaceous reducing agent, a binder was blended into the raw material mixture, and an auxiliary raw material for adjusting slag basicity was blended as necessary to obtain a blend. As the binder, wheat flour was blended.

上記スラグ塩基度調整用副原料としては、ＣａＯ供給物質として炭酸カルシウム（ＣａＣＯ3）と、ＭｇＯおよびＣａＯの供給物質としてドロマイト鉱石（主成分はＣａＣＯ3・ＭｇＣＯ3で、詳細な成分組成を下記表３に示す。）とを配合した。配合物の成分組成を下記表４に示す。 As the secondary raw materials for adjusting the slag basicity, calcium carbonate (CaCO 3 ) is used as a CaO supply substance, and dolomite ore is used as a supply substance for MgO and CaO (main components are CaCO 3 .MgCO 3. 3)). The component composition of the blend is shown in Table 4 below.

得られた配合物を成形してペレット状の原料成形体を製造した。得られた原料成形体を小型の実験用加熱還元炉内へ装入して加熱還元した。炉床上には、床敷材として表２に示す成分組成の石炭（炭素質粉末）を５ｍｍ程度の厚みで敷いた。炉内温度は１４５０℃に調整した。   The obtained blend was molded to produce a pellet-shaped raw material molded body. The obtained raw material compact was charged into a small experimental heating and reducing furnace and subjected to heat reduction. On the hearth, coal (carbonaceous powder) having the composition shown in Table 2 was laid as a floor covering material with a thickness of about 5 mm. The furnace temperature was adjusted to 1450 ° C.

加熱還元炉の炉床上に装入された原料成形体中の酸化鉄分は、約１０〜１６分かけて炉内で加熱される間に固体状態を維持しながら還元され、生成した還元鉄は、還元後に残っている炭素質粉末による浸炭を受けながら融点降下して相互に凝集した。このとき副生するスラグも、部分的、もしくはほぼ完全に溶融して相互に凝集し、溶融状態の粒状金属鉄と溶融スラグに分離した。その後、これら溶融状態の粒状金属鉄と溶融スラグを冷却して融点以下に降温（具体的には、１１００℃程度までに冷却）して凝固させ、固体状態の粒状金属鉄またはスラグとして炉外へ排出した。   The iron oxide content in the raw material compact charged on the hearth of the heating and reducing furnace is reduced while maintaining the solid state while being heated in the furnace for about 10 to 16 minutes. While undergoing carburization with the carbonaceous powder remaining after the reduction, the melting point dropped and agglomerated each other. The slag produced as a by-product at this time partially or almost completely melted and aggregated with each other, and was separated into molten metallic iron and molten slag. Thereafter, the molten granular metallic iron and molten slag are cooled, cooled to below the melting point (specifically, cooled to about 1100 ° C.) and solidified, and then discharged out of the furnace as solid granular metallic iron or slag. Discharged.

粒状金属鉄とスラグの成分組成を下記表５に示す。また、スラグに含まれるＣａＯ、ＭｇＯおよびＳｉＯ2量からスラグの塩基度［（ＣａＯ＋ＭｇＯ）／ＳｉＯ2］を算出し、下記表５に示す。 The composition of the granular metallic iron and slag is shown in Table 5 below. Further, the basicity [(CaO + MgO) / SiO 2 ] of the slag was calculated from the amounts of CaO, MgO and SiO 2 contained in the slag, and shown in Table 5 below.

また、粒状金属鉄に含まれる硫黄量［Ｓ］に対するスラグに含まれる硫黄量（Ｓ）の比（硫黄分配比（Ｓ）／［Ｓ］）を算出し、下記表５に示す。   Further, the ratio of the sulfur amount (S) contained in the slag to the sulfur amount [S] contained in the granular metallic iron (sulfur distribution ratio (S) / [S]) was calculated and shown in Table 5 below.

また、生成スラグの塩基度と硫黄分配比の関係を図２に示す。図２中、横軸は生成スラグの塩基度、縦軸は硫黄分配比を示している。図２中、◇はスラグの要件が本発明の範囲を満足する表５のＮｏ．１〜４の結果を示している。また、▲はスラグの要件が本発明の範囲を満足しない表５のＮｏ．５〜１２の結果を示している。   The relationship between the basicity of the generated slag and the sulfur distribution ratio is shown in FIG. In FIG. 2, the horizontal axis represents the basicity of the produced slag, and the vertical axis represents the sulfur distribution ratio. In FIG. 2, ◇ indicates No. in Table 5 where the slag requirement satisfies the scope of the present invention. The results of 1-4 are shown. Further, ▲ indicates the No. in Table 5 where the slag requirement does not satisfy the scope of the present invention. The result of 5-12 is shown.

また、生成スラグのＭｇＯ量と硫黄分配比の関係を図３に示す。図３中、横軸は生成スラグのＭｇＯ量（質量％）、縦軸は硫黄分配比を示している。図３中、◇はスラグの要件が本発明の範囲を満足する表５のＮｏ．１〜４の結果を示している。また、▲はスラグの要件が本発明の範囲を満足しない表５のＮｏ．５〜１２の結果を示している。   FIG. 3 shows the relationship between the amount of MgO in the generated slag and the sulfur distribution ratio. In FIG. 3, the horizontal axis represents the MgO amount (mass%) of the generated slag, and the vertical axis represents the sulfur distribution ratio. In FIG. 3, No. in Table 5 where slag requirements satisfy the scope of the present invention. The results of 1-4 are shown. Further, ▲ indicates the No. in Table 5 where the slag requirement does not satisfy the scope of the present invention. The result of 5-12 is shown.

また、配合計算から求められるＦｅ量に対して、凝集して粒状金属鉄として得られたＦｅ量の歩留まり率を算出した。歩留まり率が９５％以上ものを凝集性が良好（○）、歩留まり率が９５％未満のものを凝集性が不良（×）として評価した。評価結果を下記表５に示す。   Moreover, the yield rate of the amount of Fe obtained by agglomerating as granular metallic iron was calculated with respect to the amount of Fe obtained from the blending calculation. A product having a yield rate of 95% or more was evaluated as good cohesiveness (◯), and a product having a yield rate of less than 95% was evaluated as poor cohesiveness (x). The evaluation results are shown in Table 5 below.

表５と図２と図３から明らかなように、スラグの塩基度とＭｇＯ量を本発明の範囲内とすることで、硫黄分配比（Ｓ）／［Ｓ］を１０以上確保でき、粒状金属鉄の硫黄含有量を０．０８０％以下に抑えることができる。   As is apparent from Table 5, FIG. 2 and FIG. 3, by making the basicity of slag and the amount of MgO within the scope of the present invention, a sulfur distribution ratio (S) / [S] of 10 or more can be secured, and granular metal The sulfur content of iron can be suppressed to 0.080% or less.

また、表５から明らかなように、ＭｇＯ量を本発明の範囲内とすれば、粒状金属鉄の歩留まりを９９．０％以上に高めることができる。   Further, as apparent from Table 5, when the MgO amount is within the range of the present invention, the yield of granular metallic iron can be increased to 99.0% or more.

以上の通り、本発明では、スラグ中のＣａＯ、ＭｇＯ、ＳｉＯ2の量から求められる最終スラグの塩基度を１．５〜２．２の範囲内とし、且つスラグのＭｇＯ量が１３％を超え、２５％以下となるように調整することによって、硫黄分配比を１０以上にすることができ、得られる粒状金属鉄の硫黄含有量［Ｓ］を０．０８０％以下に低減できることが実証された。 As described above, in the present invention, the basicity of the final slag determined from the amounts of CaO, MgO, and SiO 2 in the slag is within the range of 1.5 to 2.2, and the MgO amount of the slag exceeds 13%. By adjusting to be 25% or less, it was demonstrated that the sulfur distribution ratio can be made 10 or more, and the sulfur content [S] of the obtained granular metal iron can be reduced to 0.080% or less. .

Figure 0005096811
Figure 0005096811

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図１は、回転炉床式の加熱還元炉の一構成例を示す概略説明図である。FIG. 1 is a schematic explanatory view showing a configuration example of a rotary hearth-type heating reduction furnace. 図２は、得られたスラグの塩基度と硫黄分配比の関係を示すグラフである。FIG. 2 is a graph showing the relationship between the basicity of the obtained slag and the sulfur distribution ratio. 図３は、得られたスラグのＭｇＯ量と硫黄分配比の関係を示すグラフである。FIG. 3 is a graph showing the relationship between the MgO content of the obtained slag and the sulfur distribution ratio.

符号の説明Explanation of symbols

Ａ 回転炉床式の加熱還元炉
１ 原料混合物
２ 炭素質粉末
３ 原料投入ホッパー
４ 回転炉床
５ 加熱バーナー
６ 排出装置
７ 排ガス用ダクト
８ 炉体
９ ホッパー
１０ 粒状金属鉄 A Rotary hearth type heating reduction furnace 1 Raw material mixture 2 Carbonaceous powder 3 Raw material charging hopper 4 Rotary hearth 5 Heating burner 6 Discharge device 7 Exhaust gas duct 8 Furnace body 9 Hopper 10 Granular metal iron

Claims (7)

酸化鉄含有物質と炭素質還元剤を含む原料混合物を、移動炉床式加熱還元炉の炉床上に装入して加熱し、該原料混合物中の酸化鉄を炭素質還元剤により還元し、生成する金属鉄を副生するスラグと分離しつつ粒状に凝集させた後、冷却凝固させて粒状金属鉄を製造する方法において、
前記原料混合物に含まれるＣａＯ供給物質、ＭｇＯ供給物質およびＳｉＯ2供給物質の量を調整することによって、
（１）スラグ中のＣａＯ、ＭｇＯおよびＳｉＯ2の含有量から求められる該スラグの塩基度［（ＣａＯ＋ＭｇＯ）／ＳｉＯ2］を１．５〜２．２の範囲とし、
（２）該スラグ中のＭｇＯの含有量を１３％（質量％の意味。以下同じ）超、２５％以下とすること特徴とする低硫黄含有量の粒状金属鉄の製造方法。 A raw material mixture containing an iron oxide-containing substance and a carbonaceous reducing agent is charged on the hearth of a moving hearth-type heating reduction furnace and heated, and iron oxide in the raw material mixture is reduced by a carbonaceous reducing agent to produce In a method for producing granular metallic iron by agglomerating into granular while separating from metallic slag as a by-product, and then solidifying by cooling,
By adjusting the amount of CaO supply material, MgO supply material and SiO 2 supply material contained in the raw material mixture,
(1) The basicity [(CaO + MgO) / SiO 2 ] of the slag determined from the contents of CaO, MgO and SiO 2 in the slag is in the range of 1.5 to 2.2,
(2) A method for producing granular metallic iron with a low sulfur content, characterized in that the content of MgO in the slag is more than 13% (meaning mass%; the same shall apply hereinafter) and 25% or less. 前記原料混合物に含まれる前記ＭｇＯ供給物質以外のＭｇＯ供給物質、および／または、前記原料混合物に含まれる前記ＣａＯ供給物質以外のＣａＯ供給物質を更に配合する請求項１に記載の製造方法。   The manufacturing method of Claim 1 which further mix | blends MgO supply substance other than the said MgO supply substance contained in the said raw material mixture, and / or CaO supply substance other than the said CaO supply substance contained in the said raw material mixture. ＭｇＯおよびＣａＯの供給物質として、ドロマイト鉱石を配合する請求項２に記載の製造方法。   The manufacturing method of Claim 2 which mix | blends a dolomite ore as a supply substance of MgO and CaO. 前記原料混合物に含まれる前記ＭｇＯ供給物質以外のＭｇＯ供給物質として、ＭｇＯおよび／または炭酸マグネシウムを配合する請求項２または３に記載の製造方法。   The manufacturing method of Claim 2 or 3 which mix | blends MgO and / or magnesium carbonate as MgO supply substances other than the said MgO supply substance contained in the said raw material mixture. 前記原料混合物に含まれる前記ＣａＯ供給物質以外のＣａＯ供給物質として、ＣａＯおよび／または炭酸カルシウムを配合する請求項２または３に記載の製造方法。   The manufacturing method of Claim 2 or 3 which mix | blends CaO and / or calcium carbonate as CaO supply substances other than the said CaO supply substance contained in the said raw material mixture. 請求項１〜５のいずれかに記載の製造方法で副生されるスラグ。   The slag byproduced by the manufacturing method in any one of Claims 1-5. （１）スラグ中のＣａＯ、ＭｇＯおよびＳｉＯ2の含有量から求められる該スラグの塩基度［（ＣａＯ＋ＭｇＯ）／ＳｉＯ2］が１．５〜２．２で、（２）該スラグ中のＭｇＯ含有量が１３％超、２５％以下である請求項６に記載のスラグ。 (1) The basicity [(CaO + MgO) / SiO 2 ] of the slag determined from the contents of CaO, MgO and SiO 2 in the slag is 1.5 to 2.2, and (2) the MgO content in the slag The slag according to claim 6 whose quantity is more than 13% and 25% or less.
JP2007169628A 2007-06-27 2007-06-27 Manufacturing method of granular metallic iron Expired - Fee Related JP5096811B2 (en)

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RU2010102537/02A RU2449023C2 (en) 2007-06-27 2008-06-09 Manufacturing method of granulated metallic iron
PCT/JP2008/060530 WO2009001663A1 (en) 2007-06-27 2008-06-09 Process for production of granular metallic iron
AU2008268694A AU2008268694B2 (en) 2007-06-27 2008-06-09 Method for manufacturing granular metallic iron
US12/666,729 US20100171072A1 (en) 2007-06-27 2008-06-09 Method for manufacturing granular metallic iron

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