JP2014062321A - Method of manufacturing reduced iron agglomerated product - Google Patents
Method of manufacturing reduced iron agglomerated product Download PDFInfo
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- JP2014062321A JP2014062321A JP2013173616A JP2013173616A JP2014062321A JP 2014062321 A JP2014062321 A JP 2014062321A JP 2013173616 A JP2013173616 A JP 2013173616A JP 2013173616 A JP2013173616 A JP 2013173616A JP 2014062321 A JP2014062321 A JP 2014062321A
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- iron
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/10—Making spongy iron or liquid steel, by direct processes in hearth-type furnaces
- C21B13/105—Rotary hearth-type furnaces
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/16—Sintering; Agglomerating
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/24—Binding; Briquetting ; Granulating
- C22B1/242—Binding; Briquetting ; Granulating with binders
- C22B1/244—Binding; Briquetting ; Granulating with binders organic
Abstract
Description
本発明は、酸化鉄含有物質、炭素質還元剤、および融点調整剤を含む混合物を原料とした塊成物を、移動炉床式加熱炉の炉床上に装入して加熱し、該塊成物中の酸化鉄を還元溶融して還元鉄塊成物を製造する方法に関するものである。 In the present invention, an agglomerate made of a mixture containing an iron oxide-containing substance, a carbonaceous reducing agent, and a melting point modifier is charged on the hearth of a moving hearth-type heating furnace and heated. The present invention relates to a method for producing a reduced iron agglomerate by reducing and melting iron oxide in a product.
鉄鉱石や酸化鉄等の酸化鉄源（以下、「酸化鉄含有物質」ということがある）、炭素を含む還元剤（以下、「炭素質還元剤」ということがある）、および石灰石、蛍石、ドロマイト鉱石などの融点調整剤を含む原料混合物から、塊状（粒状も含む）の金属鉄（還元鉄）を得る直接還元製鉄法が開発されてきている。この製鉄法では、上記原料混合物を成形した塊成物を移動炉床式加熱炉の炉床上に装入し、炉内で加熱バーナーによるガス伝熱や輻射熱で加熱することによって、塊成物中の酸化鉄を炭素質還元剤で還元し、得られた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塊状に凝集させた後、冷却凝固させて塊状の金属鉄（還元鉄塊成物）を得ている。 Iron oxide sources such as iron ore and iron oxide (hereinafter sometimes referred to as “iron oxide-containing substances”), carbon-containing reducing agents (hereinafter sometimes referred to as “carbonaceous reducing agents”), limestone, and fluorite In addition, a direct reduction iron manufacturing method has been developed to obtain massive (including granular) metallic iron (reduced iron) from a raw material mixture containing a melting point modifier such as dolomite ore. In this iron making method, the agglomerate formed from the above raw material mixture is placed on the hearth of a moving hearth-type heating furnace and heated in the agglomerate by gas heat transfer or radiant heat by a heating burner. The resulting reduced iron is subsequently carburized and melted, and then aggregated in a lump while separating from by-product slag, and then cooled and solidified to form a lump of metallic iron ( Reduced iron agglomerates).
こうした製鉄法は、高炉等の大規模な設備が不要なことや、コークスが不要になるなど資源面の柔軟性も高いことから、最近、実用化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、生産性などを含めて更に改善しなければならない課題も多い。 Recently, practical research has been actively conducted on such iron making methods because large-scale facilities such as a blast furnace are not required and coke is not required. However, for implementation on an industrial scale, there are many problems that must be further improved, including operational stability, safety, economy, and productivity.
特に還元鉄塊成物の製造に当たっては、粒径の大きな還元鉄塊成物の歩留まりを向上させることが望まれている。こうした技術として、例えば特許文献１には、「金属酸化物含有物質と炭素質還元剤とを含む原料を加熱し、該原料中の金属酸化物を還元した後、生成する金属を更に加熱して溶融させると共に、副生するスラグ成分と分離させながら凝集させて粒状金属を生成する方法において、前記原料中に副生スラグの凝集促進剤を配合する粒状金属鉄の製造。」が提案されている。この文献に開示されている技術では、凝集促進剤（例えば、蛍石など）を配合することによって、粒径の大きな粒状金属が、ある程度高い歩留まりで製造できることが期待できる。しかしながら、こうした技術においても、歩留まり改善効果は飽和状態にあり、更なる効果の向上が望まれている。 Particularly in the production of reduced iron agglomerates, it is desired to improve the yield of reduced iron agglomerates having a large particle size. As such a technique, for example, Patent Document 1 discloses that “a raw material containing a metal oxide-containing substance and a carbonaceous reducing agent is heated, and after reducing the metal oxide in the raw material, the produced metal is further heated. In the method of melting and agglomerating while separating from by-product slag components to produce a granular metal, production of granular metallic iron in which a coagulation accelerator for by-product slag is blended in the raw material has been proposed. . In the technique disclosed in this document, it can be expected that a granular metal having a large particle diameter can be produced with a somewhat high yield by blending an aggregation accelerator (for example, fluorite). However, even in such a technique, the yield improvement effect is in a saturated state, and further improvement of the effect is desired.
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、移動炉床式加熱炉で、酸化鉄含有物質、炭素質還元剤、および融点調整剤を含む混合物を原料とした塊成物を加熱し、原料混合物中の酸化鉄を還元溶融して還元鉄塊成物を製造するにあたり、粒径の大きな還元鉄塊成物の歩留まりを向上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 a moving hearth-type heating furnace using a mixture containing an iron oxide-containing substance, a carbonaceous reducing agent, and a melting point modifier as a raw material. An object of the present invention is to provide a method capable of improving the yield of reduced iron agglomerates having a large particle size in the production of reduced iron agglomerates by heating the agglomerates and reducing and melting iron oxide in the raw material mixture.
上記課題を解決することのできた本発明に係る還元鉄塊成物の製造方法とは、酸化鉄含有物質、炭素質還元剤、および融点調整剤を含んでなる塊成物を、移動炉床式加熱炉の炉床上に装入して加熱することによって、該塊成物中の酸化鉄を還元し、更に加熱して少なくとも部分的に溶融し、鉄成分を凝集させて還元鉄塊成物を製造する方法であり、前記炭素質還元剤として、平均粒径が４０〜１６０μｍで、且つ粒径が４００μｍ以上のものを２質量％以上含む炭素質還元剤を用いる点に要旨を有している。 The method for producing a reduced iron agglomerate according to the present invention that has solved the above problems includes an agglomerate comprising an iron oxide-containing substance, a carbonaceous reducing agent, and a melting point regulator, and a moving hearth type By charging on the hearth of the heating furnace and heating, the iron oxide in the agglomerate is reduced, further heated to at least partially melt, and the iron component is agglomerated to reduce the reduced iron agglomerate. It is a manufacturing method, and the carbonaceous reducing agent is characterized in that a carbonaceous reducing agent having an average particle diameter of 40 to 160 μm and a particle diameter of 400 μm or more containing 2% by mass or more is used. .
前記酸化鉄含有物質としては、具体的には、鉄鉱石が挙げられる。前記塊成物に含まれる炭素量と全鉄量との比（炭素量／全鉄量）は、０．３８４以下であることが好ましい。 Specific examples of the iron oxide-containing substance include iron ore. The ratio of the amount of carbon and the amount of total iron contained in the agglomerate (carbon amount / total iron amount) is preferably 0.384 or less.
本発明によれば、酸化鉄含有物質、炭素質還元剤、および融点調整剤を含む混合物を原料とした塊成物を、移動炉床式加熱炉の炉床上に装入して加熱し、該塊成物中の酸化鉄を還元溶融して還元鉄塊成物を製造するに際して、炭素質還元剤の平均粒径および粒度分布を適切に制御することによって、粒径の大きな還元鉄塊成物の歩留まりを向上できる。 According to the present invention, an agglomerate made from a mixture containing an iron oxide-containing substance, a carbonaceous reducing agent, and a melting point modifier is charged on the hearth of a moving hearth-type heating furnace and heated, When producing reduced iron agglomerates by reducing and melting iron oxide in the agglomerates, reduced iron agglomerates having a large particle size are appropriately controlled by appropriately controlling the average particle size and particle size distribution of the carbonaceous reducing agent. Yield can be improved.
還元鉄塊成物を製造するに際し、その原料である酸化鉄含有物質、炭素質還元剤、および融点調整剤を含む混合物からなる塊成物を形成するに当たっては、酸化鉄含有物質および炭素質還元剤は適度の粉砕が施されて、造粒しやすいように適度の大きさに揃えられている。しかしながら、これらの原料の大きさ（平均粒径）が還元鉄塊成物の歩留まりに与える影響については考慮されることはなかった。むしろ、特に粗大な炭素質還元剤を用いると、酸化鉄含有物質との接触が悪くなったり、炭素質還元剤の比表面積が減少し、炭素質還元剤のガス化速度が小さくなるため、還元鉄塊成物の歩留まりは低下すると考えられる。 In producing a reduced iron agglomerate, an iron oxide-containing substance and a carbonaceous reduction are used to form an agglomerate composed of a mixture containing an iron oxide-containing substance, a carbonaceous reducing agent, and a melting point modifier as raw materials. The agent is moderately pulverized and is sized to facilitate granulation. However, the influence of the size (average particle size) of these raw materials on the yield of reduced iron agglomerates has not been considered. Rather, when a coarse carbonaceous reducing agent is used, the contact with the iron oxide-containing substance is deteriorated, the specific surface area of the carbonaceous reducing agent is reduced, and the gasification rate of the carbonaceous reducing agent is reduced. The yield of iron agglomerates is thought to decrease.
ところが、本発明者らは、上記目的に達成するために、様々な角度から検討した。特に、還元鉄塊成物を製造する際に用いる原料の平均粒径や粒度分布が、還元鉄塊成物の歩留まりに与える影響について検討した。その結果、原料のうち炭素質還元剤の平均粒径および粒度分布を適切に調整すれば、上記目的が見事に達成されることを見出し、本発明を完成した。以下、本発明について詳細に説明する。 However, the present inventors have studied from various angles in order to achieve the above object. In particular, the influence of the average particle size and particle size distribution of raw materials used when producing reduced iron agglomerates on the yield of reduced iron agglomerates was examined. As a result, the inventors have found that the above object can be achieved brilliantly by appropriately adjusting the average particle size and particle size distribution of the carbonaceous reducing agent in the raw material, and completed the present invention. Hereinafter, the present invention will be described in detail.
本発明では、塊成物に含まれる炭素質還元剤の平均粒径を４０〜１６０μｍとし、且つ炭素質還元剤の総量に対して粒径が４００μｍ以上の炭素質還元剤を２質量％以上含む炭素質還元剤を用いる必要がある。尚、本明細書において、平均粒径とは、粒子サイズが小さいものから順に粒子の質量を測定したときに、積算値が５０質量％に相当するときの粒径（以下、「Ｄ５０」と記載することがある）を意味する。 In the present invention, the average particle size of the carbonaceous reducing agent contained in the agglomerate is 40 to 160 μm, and the carbonaceous reducing agent having a particle size of 400 μm or more with respect to the total amount of the carbonaceous reducing agent is contained by 2% by mass or more. It is necessary to use a carbonaceous reducing agent. In this specification, the average particle diameter is the particle diameter when the integrated value corresponds to 50% by mass (hereinafter referred to as “D50”) when the mass of the particles is measured in order from the smallest particle size. Mean).
上記炭素質還元剤の平均粒径は、好ましくは１５０μｍ以下、より好ましくは１００μｍ以下であり、好ましくは５０μｍ以上、より好ましくは６０μｍ以上である。 The average particle diameter of the carbonaceous reducing agent is preferably 150 μm or less, more preferably 100 μm or less, preferably 50 μm or more, more preferably 60 μm or more.
上記粒径が４００μｍ以上の炭素質還元剤は、炭素質還元剤の総量に対して５質量％以上含有していることが好ましく、より好ましくは１０質量％以上、更に好ましくは２０質量％以上である。 The carbonaceous reducing agent having a particle size of 400 μm or more is preferably contained in an amount of 5% by mass or more, more preferably 10% by mass or more, and further preferably 20% by mass or more based on the total amount of the carbonaceous reducing agent. is there.
上記炭素質還元剤としては、炭素を含有する物質を用いればよく、例えば、石炭やコークスなどを用いればよい。 As the carbonaceous reducing agent, a substance containing carbon may be used. For example, coal or coke may be used.
本発明では、上記要件を満足する炭素質還元剤と、酸化鉄含有物質および融点調整剤を含む塊成物を、移動炉床式加熱炉の炉床上に装入して加熱し、還元鉄塊成物を製造する。 In the present invention, an agglomerate containing a carbonaceous reducing agent satisfying the above requirements, an iron oxide-containing substance and a melting point modifier is charged on the hearth of a moving hearth-type heating furnace and heated, and the reduced iron ingot Manufacture the composition.
上記酸化鉄含有物質としては、例えば、鉄鉱石や砂鉄、非鉄製錬残渣などを用いればよく、好ましくは鉄鉱石を用いるのがよい。 As the iron oxide-containing substance, for example, iron ore, iron sand, non-ferrous smelting residue or the like may be used, and iron ore is preferably used.
上記塊成物に含まれる炭素量と全鉄量との比（炭素量／全鉄量）は、０．３８４以下であることが好ましい。炭素量と全鉄量との比を０．３８４以下に抑えることにより、粒径の大きな還元鉄塊成物の歩留まりを向上でき、しかも還元鉄塊成物の品質も向上させることができる。即ち、還元鉄塊成物に含まれるＳ量を低減したり、Ｃ量を増加させて品質を向上させるには、炭素質還元剤の配合量を多くすることが考えられるが、炭素質還元剤の配合量を多くし過ぎると、粒径の大きな還元鉄塊成物の歩留まりは低下する傾向が認められた。そこで、本発明では、上述したように炭素質還元剤の平均粒径および粒度分布を調整したうえで、炭素質還元剤の配合量および酸化鉄含有物質の配合量を調整し、塊成物に含まれる炭素量と全鉄量との比を０．３８４以下とすることが好ましい。塊成物に含まれる炭素量と全鉄量との比は、より好ましくは０．３８０以下であり、更に好ましくは０．３７０以下である。 The ratio of the amount of carbon and the amount of total iron contained in the agglomerate (carbon amount / total iron amount) is preferably 0.384 or less. By suppressing the ratio of the carbon amount to the total iron amount to 0.384 or less, the yield of reduced iron agglomerates having a large particle size can be improved, and the quality of the reduced iron agglomerates can also be improved. That is, to reduce the amount of S contained in the reduced iron agglomerate or increase the amount of C to improve the quality, it is conceivable to increase the amount of the carbonaceous reducing agent. When the blending amount was too large, the yield of reduced iron agglomerates having a large particle size tended to decrease. Therefore, in the present invention, as described above, after adjusting the average particle size and particle size distribution of the carbonaceous reducing agent, the blending amount of the carbonaceous reducing agent and the blending amount of the iron oxide-containing substance are adjusted to obtain an agglomerate. The ratio of the amount of carbon contained and the amount of total iron is preferably 0.384 or less. The ratio of the amount of carbon contained in the agglomerate and the amount of total iron is more preferably 0.380 or less, and still more preferably 0.370 or less.
上記融点調整剤としては、例えば、ＣａＯ供給物質、ＭｇＯ供給物質、Ａｌ2Ｏ3供給物質、ＳｉＯ2供給物質、蛍石、ドロマイト鉱石等を用いればよい。 As the melting point adjusting agent, for example, a CaO supply material, a MgO supply material, an Al 2 O 3 supply material, a SiO 2 supply material, fluorite, dolomite ore, etc. may be used.
上記ＣａＯ供給物質としては、例えば、生石灰（ＣａＯ）、消石灰［Ｃａ（ＯＨ）2］や石灰石（主成分はＣａＣＯ3）などを用いることができる。上記ＭｇＯ供給物質としては、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）などを用いることができる。上記Ａｌ2Ｏ3供給物質としては、例えば、Ａｌ2Ｏ3粉末、ボーキサイト、ベーマイト、ギブサイト、ダイアスポアなどを用いることができる。上記ＳｉＯ2供給物質としては、例えば、ＳｉＯ2粉末や珪砂などを用いることができる。上記ドロマイト鉱石とは、炭酸カルシウムと炭酸マグネシウムの複塩である。 As the CaO feed materials, for example, quick lime (CaO), slaked lime [Ca (OH) 2] or limestone (main component CaCO 3) or the like can be used. As the MgO feed materials, for example, Mg-containing substance to be extracted such as from MgO powder and natural ore or seawater, or magnesium carbonate (MgCO 3) or the like can be used. Examples of the Al 2 O 3 supply substance include Al 2 O 3 powder, bauxite, boehmite, gibbsite, and diaspore. As the SiO 2 supply substance, for example, SiO 2 powder or silica sand can be used. The dolomite ore is a double salt of calcium carbonate and magnesium carbonate.
上記原料混合物には、その他の成分として、バインダーなどを配合してもよい。バインダーとしては、例えば、多糖類（例えば、小麦粉等の澱粉など）などを用いることができる。 You may mix | blend a binder etc. with the said raw material mixture as another component. As the binder, for example, a polysaccharide (for example, starch such as wheat flour) can be used.
上記塊成物の形状は特に限定されず、例えば、ペレット状やブリケット状などであればよい。 The shape of the agglomerate is not particularly limited, and may be, for example, a pellet shape or a briquette shape.
上記塊成物の大きさも特に限定されないが、粒径（最大粒径）は５０ｍｍ以下であることが好ましい。塊成物の粒径を過剰に大きくしようとすると、造粒効率が悪くなる。また、塊成物の下部への伝熱が悪くなり、生産性が低下する。なお、塊成物の粒径の下限値は５ｍｍ程度である。 The size of the agglomerate is not particularly limited, but the particle size (maximum particle size) is preferably 50 mm or less. If the particle size of the agglomerate is excessively increased, the granulation efficiency is deteriorated. In addition, heat transfer to the lower part of the agglomerate is deteriorated, and productivity is lowered. In addition, the lower limit of the particle size of the agglomerate is about 5 mm.
上記移動炉床式加熱炉とは、炉床がベルトコンベアのように炉内を移動する加熱炉であり、例えば、回転炉床炉やトンネル炉が挙げられる。 The moving hearth type heating furnace is a heating furnace in which the hearth moves in the furnace like a belt conveyor, and examples thereof include a rotary hearth furnace and a tunnel furnace.
上記回転炉床炉は、炉床の始点と終点が同じ位置になるように、炉床の外観形状が円形（ドーナツ状）に設計されており、炉床上に供給された塊成物は、炉内を一周する間に加熱還元されて（粒状）金属鉄を生成する。従って、回転炉床炉には、回転方向の最上流側に塊成物を炉内に供給する装入手段が設けられ、回転方向の最下流側（回転構造であるため、実際には装入手段の直上流側になる）に排出手段が設けられる。 The rotary hearth furnace is designed so that the outer shape of the hearth is circular (donut-shaped) so that the start point and end point of the hearth are in the same position. During one round of the inside, it is reduced by heating to produce (granular) metallic iron. Therefore, the rotary hearth furnace is provided with charging means for supplying the agglomerate into the furnace on the most upstream side in the rotation direction, and the most downstream side in the rotation direction (since it is a rotating structure, Discharging means is provided immediately upstream of the means).
上記トンネル炉とは、炉床が直線方向に炉内を移動する加熱炉である。 The tunnel furnace is a heating furnace in which the hearth moves in the furnace in a linear direction.
上記塊成物は、上記移動炉床式加熱炉内で、例えば、１３００〜１５００℃で加熱して加熱還元すればよい。 The agglomerate may be heated and reduced, for example, by heating at 1300 to 1500 ° C. in the moving hearth type heating furnace.
上記移動炉床式加熱炉の炉床上には、上記塊成物を炉内に装入するに先立って、床敷材を敷くことも好ましい態様である。床敷材を敷くことによって炉床を保護できる。 It is also a preferable aspect that a floor covering material is laid on the hearth of the moving hearth heating furnace prior to charging the agglomerate into the furnace. You can protect the hearth by laying the floor covering.
上記床敷材としては、上記炭素質還元剤として例示したものの他、耐火性粒子を用いることができる。 As the floor covering material, refractory particles can be used in addition to those exemplified as the carbonaceous reducing agent.
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。 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.
（実施例１）
酸化鉄含有物質、炭素質還元剤、融点調整剤（石灰石、ドロマイトおよび蛍石）、およびバインダーを含む混合物を原料とした塊成物を作製し、この塊成物を、加熱炉に供給して加熱し、原料混合物中の酸化鉄を還元溶融させて還元鉄塊成物を製造した。
Example 1
An agglomerate made from a mixture containing an iron oxide-containing substance, a carbonaceous reducing agent, a melting point modifier (limestone, dolomite and fluorite), and a binder is prepared, and this agglomerate is supplied to a heating furnace. The mixture was heated to reduce and melt iron oxide in the raw material mixture to produce a reduced iron agglomerate.
上記酸化鉄含有物質としては、下記表１に示した成分組成の鉄鉱石を用いた。下記表１において、Ｔ．Ｆｅは全鉄を示している。上記炭素質還元剤としては、下記表２に示した成分組成の石炭を用いた。上記融点調整剤としては、下記表３に示した主たる成分組成の石灰石、下記表４に示した主たる成分組成のドロマイト、下記表５に示した主たる成分組成の蛍石を用いた。上記バインダーとしては、小麦粉を用いた。 As the iron oxide-containing substance, iron ore having the component composition shown in Table 1 below was used. In Table 1 below, T.W. Fe indicates total iron. As the carbonaceous reducing agent, coal having the component composition shown in Table 2 below was used. As the melting point adjusting agent, limestone having the main component composition shown in Table 3 below, dolomite having the main component composition shown in Table 4 below, and fluorite having the main component composition shown in Table 5 below were used. As the binder, flour was used.
鉄鉱石、石炭、石灰石、ドロマイト、蛍石、およびバインダー（小麦粉）を、下記表６に示す配合率で混合し、この混合物に適量の水を添加し、タイヤ型造粒機を用いて直径が１９ｍｍの生ペレットに造粒した。このとき石炭（炭素質還元剤）の平均粒径（Ｄ５０）を変化させて生ペレットを造粒した。用いた石炭の平均粒径（Ｄ５０）を下記表７に示す。また、下記表７には、用いた石炭の質量に対する、粒径が４００μｍ以上の石炭の含有量（下記表７では、石炭中の＋４００μｍ含有量と表記）を示す。 Iron ore, coal, limestone, dolomite, fluorite, and binder (flour) are mixed at the blending ratio shown in Table 6 below, an appropriate amount of water is added to the mixture, and the diameter is reduced using a tire-type granulator. Granulated into 19 mm raw pellets. At this time, raw pellets were granulated by changing the average particle diameter (D50) of coal (carbonaceous reducing agent). The average particle size (D50) of the coal used is shown in Table 7 below. Table 7 below shows the content of coal having a particle size of 400 μm or more with respect to the mass of the coal used (in Table 7 below, expressed as +400 μm content in coal).
次に、得られた生ペレットを乾燥機に装入し、１８０℃で１時間加熱して付着水を除去してペレット状塊成物（球状の乾燥ペレット）を作製した。下記表７に、乾燥ペレットの一般的な性状として見掛け密度を測定した結果を示す。また、下記表７には、乾燥ペレットの分析値として、乾燥ペレットに含まれるＴ．Ｆｅ（全鉄量）も併せて示した。なお、乾燥ペレットの見掛け密度および分析値は、いずれも１０個の乾燥ペレットについて測定した結果の平均値である。 Next, the obtained raw pellets were charged into a dryer and heated at 180 ° C. for 1 hour to remove the adhering water to produce pellet-like agglomerates (spherical dry pellets). Table 7 below shows the results of measuring the apparent density as a general property of the dried pellets. In Table 7 below, as an analysis value of the dry pellet, T.O. Fe (total iron amount) is also shown. Note that the apparent density and analysis value of the dry pellets are average values of the results of measurement for 10 dry pellets.
次に、得られた乾燥ペレットを、炭材（最大粒径が２ｍｍ以下の無煙炭）を敷いた加熱炉内へ装入し、１４５０℃の窒素雰囲気で加熱し、還元鉄塊成物を製造した。このとき還元溶融に必要な時間（反応時間）を測定した。結果を下記表７に示した。 Next, the obtained dry pellets were charged into a heating furnace laid with a carbonaceous material (anthracite having a maximum particle size of 2 mm or less) and heated in a nitrogen atmosphere at 1450 ° C. to produce a reduced iron agglomerate. . At this time, the time required for reductive melting (reaction time) was measured. The results are shown in Table 7 below.
得られた還元鉄塊成物について、直径が３．３５ｍｍ以上の還元鉄塊成物の歩留まりを算出すると共に、還元鉄塊成物の分析値を測定した。 About the obtained reduced iron agglomerate, while calculating the yield of the reduced iron agglomerate whose diameter was 3.35 mm or more, the analytical value of the reduced iron agglomerate was measured.
［直径が３．３５ｍｍ以上の還元鉄塊成物の歩留まり］
直径が３．３５ｍｍ以上の還元鉄塊成物の歩留まりは、上記乾燥ペレット中の鉄分に対する、直径が３．３５ｍｍ以上の還元鉄塊成物の質量の割合［即ち、＋３．３５ｍｍ還元鉄塊成物の質量／乾燥ペレット中の鉄分×１００］で算出した。結果を下記表７に示す。下記表７では、直径が３．３５ｍｍ以上の還元鉄塊成物の歩留まりを、「＋３．３５ｍｍ還元鉄塊成物の歩留まり」と表記した。また、以下では、直径が３．３５ｍｍ以上の還元鉄塊成物の歩留まりを「製品回収率」と呼ぶことがある。
[Yield of reduced iron agglomerates with a diameter of 3.35 mm or more]
The yield of reduced iron agglomerates with a diameter of 3.35 mm or more is the ratio of the mass of reduced iron agglomerates with a diameter of 3.35 mm or more to the iron content in the dried pellet [ie +3.35 mm reduced iron agglomeration] Mass of product / Iron content in dry pellet × 100]. The results are shown in Table 7 below. In Table 7 below, the yield of reduced iron agglomerates having a diameter of 3.35 mm or more is represented as “+3.35 mm reduced iron agglomerate yield”. Hereinafter, the yield of reduced iron agglomerates having a diameter of 3.35 mm or more may be referred to as “product recovery rate”.
［還元鉄塊成物の分析値］
還元鉄塊成物の分析値として、還元鉄塊成物に含まれるＣ量を測定した。結果を下記表７に示す。
[Analytical value of reduced iron agglomerates]
As the analytical value of the reduced iron agglomerate, the amount of C contained in the reduced iron agglomerate was measured. The results are shown in Table 7 below.
下記表７から明らかなように、石炭（炭素質還元剤）の平均粒径（Ｄ５０）を４０〜１６０μｍとすると共に、粒径が４００μｍ以上のものの石炭中の含有量を２質量％以上とすることによって、還元鉄塊成物の歩留まりが８５％以上に向上することが分かる。 As is apparent from Table 7 below, the average particle diameter (D50) of coal (carbonaceous reducing agent) is 40 to 160 μm, and the content in the coal having a particle diameter of 400 μm or more is 2 mass% or more. This shows that the yield of reduced iron agglomerates is improved to 85% or more.
（実施例２）
上記実施例１と同様、酸化鉄含有物質、炭素質還元剤、融点調整剤（石灰石、ドロマイトおよび蛍石）、およびバインダーを含む混合物を原料とした塊成物を作製し、この塊成物を、加熱炉に供給して加熱し、原料混合物中の酸化鉄を還元溶融させて還元鉄塊成物を製造した。但し、実施例２では、上記実施例１で用いた炭素質還元剤とは異なる種類の炭素質還元剤を用いると共に、鉄鉱石、石炭、石灰石、ドロマイト、蛍石、およびバインダー（小麦粉）の配合率を変えて製造した生ペレットを用いた。
(Example 2)
As in Example 1 above, an agglomerate was produced from a mixture containing an iron oxide-containing substance, a carbonaceous reducing agent, a melting point modifier (limestone, dolomite, and fluorite), and a binder. Then, it was supplied to a heating furnace and heated to reduce and melt the iron oxide in the raw material mixture to produce a reduced iron agglomerate. However, in Example 2, a carbonaceous reducing agent of a different type from the carbonaceous reducing agent used in Example 1 was used, and iron ore, coal, limestone, dolomite, fluorite, and a binder (wheat flour) were mixed. Raw pellets produced at different rates were used.
上記酸化鉄含有物質としては、下記表８に示した成分組成の鉄鉱石を用いた。上記炭素質還元剤としては、下記表９に示した成分組成の石炭を用いた。上記融点調整剤としては、下記表１０に示した主たる成分組成の石灰石、下記表１１に示した主たる成分組成のドロマイト、下記表１２に示した主たる成分組成の蛍石を用いた。上記バインダーとしては、小麦粉を用いた。 As the iron oxide-containing substance, iron ore having the component composition shown in Table 8 below was used. As the carbonaceous reducing agent, coal having the component composition shown in Table 9 below was used. As the melting point modifier, limestone having the main component composition shown in Table 10 below, dolomite having the main component composition shown in Table 11 below, and fluorite having the main component composition shown in Table 12 below were used. As the binder, flour was used.
鉄鉱石、石炭、石灰石、ドロマイト、蛍石、およびバインダー（小麦粉）を、下記表１３に示す配合率で混合し、この混合物に適量の水を添加し、タイヤ型造粒機を用いて直径が１９ｍｍの生ペレットに造粒した。石炭（炭素質還元剤）としては、平均粒径（Ｄ５０）が４１μｍまたは４３μｍのものを用いて生ペレットを造粒した。用いた石炭の平均粒径（Ｄ５０）を下記表１４に示す。また、下記表１４には、用いた石炭の質量に対する、粒径が４００μｍ以上の石炭の含有量（下記表１４では、石炭中の＋４００μｍ含有量と表記）を示す。 Iron ore, coal, limestone, dolomite, fluorite, and binder (wheat flour) are mixed at a blending ratio shown in Table 13 below, an appropriate amount of water is added to the mixture, and the diameter is reduced using a tire-type granulator. Granulated into 19 mm raw pellets. Raw coal was granulated using coal (carbonaceous reducing agent) having an average particle size (D50) of 41 μm or 43 μm. The average particle size (D50) of the coal used is shown in Table 14 below. Table 14 below shows the content of coal having a particle size of 400 μm or more with respect to the mass of the coal used (in Table 14 below, expressed as +400 μm content in coal).
次に、得られた生ペレットを乾燥機に装入し、上記実施例１と同じ条件でペレット状塊成物（球状の乾燥ペレット）を作製した。下記表１４に、乾燥ペレットの一般的な性状として見掛け密度を測定した結果を示す。また、下記表１４には、乾燥ペレットの分析値として、乾燥ペレットに含まれるＴ．Ｆｅ（全鉄量）も併せて示した。また、下記表１４には、乾燥ペレットの分析値として、乾燥ペレットに含まれるＣ量とＴ．Ｆｅ（全鉄量）との比も併せて示した。なお、乾燥ペレットの見掛け密度および分析値は、いずれも１０個の乾燥ペレットについて測定した結果の平均値である。 Next, the obtained raw pellets were charged into a dryer, and pellet-like agglomerates (spherical dry pellets) were produced under the same conditions as in Example 1 above. Table 14 below shows the result of measuring the apparent density as a general property of the dried pellets. In Table 14 below, as an analysis value of the dry pellet, T.O. Fe (total iron amount) is also shown. Table 14 below shows the amount of C contained in the dried pellet and the T.O. as an analytical value of the dried pellet. The ratio with Fe (total iron amount) is also shown. Note that the apparent density and analysis value of the dry pellets are average values of the results of measurement for 10 dry pellets.
次に、得られた乾燥ペレットを、炭材（最大粒径が２ｍｍ以下の無煙炭）を敷いた加熱炉内へ装入し、１４５０℃で加熱し、還元鉄塊成物を製造した。加熱雰囲気は、窒素ガスが６０体積％、二酸化炭素ガスが４０体積％の混合ガス雰囲気下で行った。このとき還元溶融に必要な時間（反応時間）を測定した。結果を下記表１４に示した。 Next, the obtained dry pellets were charged into a heating furnace laid with a carbonaceous material (anthracite having a maximum particle size of 2 mm or less) and heated at 1450 ° C. to produce a reduced iron agglomerate. The heating atmosphere was performed in a mixed gas atmosphere of 60% by volume of nitrogen gas and 40% by volume of carbon dioxide gas. At this time, the time required for reductive melting (reaction time) was measured. The results are shown in Table 14 below.
得られた還元鉄塊成物について、直径が３．３５ｍｍ以上の還元鉄塊成物の歩留まりを上記実施例１と同じ手順で算出すると共に、還元鉄塊成物の分析値を上記実施例１と同じ手順で測定した。結果を下記表１４に示す。 For the obtained reduced iron agglomerates, the yield of reduced iron agglomerates having a diameter of 3.35 mm or more is calculated in the same procedure as in Example 1 above, and the analytical value of the reduced iron agglomerates is calculated in Example 1 above. Measured in the same procedure as The results are shown in Table 14 below.
下記表１４から明らかなように、Ｎｏ．１１〜１７は、石炭（炭素質還元剤）の平均粒径（Ｄ５０）を４０〜１６０μｍとすると共に、粒径が４００μｍ以上のものの石炭中の含有量を２質量％以上としているため、還元鉄塊成物の歩留まりを８５％以上に向上できた。また、Ｎｏ．１２〜１７の結果について比較すると、これらの例は、いずれも、石炭の平均粒径（Ｄ５０）が４３μｍで、粒径が４００μｍ以上のものの石炭中の含有量が６．３６質量％であり、これらの中でもＮｏ．１２〜１６は、乾燥ペレット中に含有される炭素量と全鉄量との比を０．３８４以下としているため、還元鉄塊成物の歩留まりを９０％以上に向上できることが分かる。また、乾燥ペレット中に含有される炭素量と全鉄量との比を小さくするほど、還元鉄塊成物に含まれるＣ量は増加する傾向が読み取れる。 As apparent from Table 14 below, Nos. 11 to 17 have an average particle diameter (D50) of coal (carbonaceous reducing agent) of 40 to 160 μm and a content of coal having a particle diameter of 400 μm or more in the coal of 2% by mass or more. The yield of agglomerates was improved to 85% or more. No. When comparing the results of 12 to 17, all of these examples have an average particle diameter (D50) of coal of 43 μm, and the content in the coal having a particle diameter of 400 μm or more is 6.36% by mass, Among these, No. In Nos. 12 to 16, since the ratio of the amount of carbon contained in the dry pellets to the total amount of iron is 0.384 or less, it can be seen that the yield of reduced iron agglomerates can be improved to 90% or more. Further, it can be seen that the amount of C contained in the reduced iron agglomerate tends to increase as the ratio of the amount of carbon contained in the dry pellets and the amount of total iron is reduced.
Claims (3)
前記炭素質還元剤として、平均粒径が４０〜１６０μｍで、且つ粒径が４００μｍ以上のものを２質量％以上含む炭素質還元剤を用いることを特徴とする還元鉄塊成物の製造方法。 An agglomerate comprising an iron oxide-containing substance, a carbonaceous reducing agent, and a melting point modifier is charged on the hearth of a moving hearth-type heating furnace and heated to thereby heat the iron oxide in the agglomerate. A reduced iron agglomerate by further heating and at least partially melting to agglomerate iron components,
A method for producing a reduced iron agglomerate, comprising using, as the carbonaceous reducing agent, a carbonaceous reducing agent having an average particle size of 40 to 160 μm and a particle size of 2% by mass or more containing 400 μm or more.
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