JP5703715B2 - Method for producing sintered ore - Google Patents

Method for producing sintered ore Download PDF

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JP5703715B2
JP5703715B2 JP2010262620A JP2010262620A JP5703715B2 JP 5703715 B2 JP5703715 B2 JP 5703715B2 JP 2010262620 A JP2010262620 A JP 2010262620A JP 2010262620 A JP2010262620 A JP 2010262620A JP 5703715 B2 JP5703715 B2 JP 5703715B2
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隆英 樋口
隆英 樋口
大山 伸幸
伸幸 大山
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JFE Steel Corp
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Description

本発明は、下方吸引式のドワイトロイド焼結機を用いて、高強度、高品質の焼結鉱を生産性よく製造する焼結鉱の製造方法に関するものである。   The present invention relates to a method for producing a sintered ore that produces a high-strength, high-quality sintered ore with high productivity by using a downward suction type dwytroid sintering machine.

高炉用の鉄鉱石類原料として用いられる焼結鉱は、下方吸引式のドワイトロイド焼結機を用いる場合、一般に、以下のような方法で製造されている。まず、粒径が10mm以下の鉄鉱石、粒径が所定値以下の返鉱、石灰石などのCaO系副原料、珪石や蛇紋岩および各種の製錬スラグなどからなるSiO系副原料、および、粉コークスや無煙炭などの熱源となる固体燃料(粉コークス等の炭材)等から構成される造粒原料に、適当量の水分を添加してミキサーやドラムミキサー等を用いて混合・造粒して造粒粒子と呼ばれる焼結原料とする。次いで、その焼結原料を焼結機のパレット上に適当な厚さ、例えば500〜700mm程度の厚さになるように充填して焼結原料の装入層を形成し、その後、点火炉でその装入層表層部の炭材に点火し、パレット下方に配設されたウインドボックスで空気を吸引して装入層内の炭材を燃焼させ、その燃焼熱によって焼結原料を溶融させて焼結ケーキとする。その後、この焼結ケーキを破砕し、整粒して、一定の粒径以上のものを成品焼結鉱として高炉に装入し、それ未満のものは返鉱として、再度焼結原料の原料として利用している。 In general, a sintered ore used as a raw material for iron ore for a blast furnace is manufactured by the following method when using a downward suction type dwythroid sintering machine. First, an iron ore having a particle size of 10 mm or less, a return mineral having a particle size of a predetermined value or less, a CaO-based auxiliary material such as limestone, a SiO 2- based auxiliary material made of silica stone, serpentine, various smelting slags, and the like, and Add a suitable amount of water to a granulated raw material consisting of solid fuel (carbon material such as powdered coke) that becomes a heat source such as powdered coke and anthracite, and mix and granulate using a mixer or drum mixer. Thus, a sintered raw material called granulated particles is used. Next, the sintered raw material is filled on a pallet of a sintering machine so as to have an appropriate thickness, for example, a thickness of about 500 to 700 mm, to form a charged layer of the sintered raw material, and then in an ignition furnace The charcoal material in the surface layer of the charging layer is ignited, and air is sucked in the wind box disposed below the pallet to burn the charcoal material in the charging layer, and the sintering heat is used to melt the sintering raw material. Let it be a sintered cake. After that, this sintered cake is crushed and sized, and the one with a certain particle size or more is charged into the blast furnace as a product sintered ore, and the one less than that is returned to the blast furnace as the raw material of the sintering raw material again. We are using.

図1は、点火炉によって点火された装入層表層の炭材が、吸引される空気によって燃焼して燃焼・溶融帯を形成し、その燃焼・溶融帯がパレットが下流側に移動して行くのに伴い装入層の上層から下層に順次移動していき、燃焼・溶融帯が通過した後には、焼結が完了した焼結ケーキ層(焼結層)が形成されていることを模式的に示したものである。
ここで、上記燃焼・溶融帯は、溶融物がウインドボックスにより吸引される空気の通過を阻害するため、通気抵抗を高める要因となる。また、上記燃焼・溶融帯が上層から下層に移行するのにともない、焼結原料中に含まれる水分は、炭材の燃焼熱で気化し、まだ温度が上昇していない下層の焼結原料中に凝縮して濃縮し、湿潤帯を形成する。そして、上記水分量が増加すると、吸引した空気の流路となる焼結原料粒子間の空隙が水分で埋まり、通気抵抗を増大させる。
Fig. 1 shows that the carbon material in the surface layer of the charging layer ignited by the ignition furnace is combusted by sucked air to form a combustion / melting zone, and the combustion / melting zone moves to the downstream side of the pallet. As a result, it gradually moves from the upper layer to the lower layer of the charging layer, and after passing the combustion / melting zone, a sintered cake layer (sintered layer) that has been sintered is formed. It is shown in.
Here, the combustion / melting zone inhibits the passage of the air in which the melt is sucked by the wind box, and thus increases the ventilation resistance. In addition, as the combustion / melting zone shifts from the upper layer to the lower layer, the moisture contained in the sintering raw material is vaporized by the combustion heat of the carbonaceous material, and the temperature in the lower sintering raw material that has not yet risen is increased. Condensed and concentrated to form a wet zone. And if the said moisture content increases, the space | gap between the sintering raw material particles used as the flow path of the attracted air will be filled with moisture, and ventilation resistance will be increased.

図2は、燃焼・溶融帯の最高到達温度域が、厚さが600mmの装入層表層から200mm下方位置に存在するときの装入層内における圧損と温度の分布を示したものである。この図から、装入層内の圧損分布は、湿潤帯におけるものが約60%を占め、残りの40%が燃焼・溶融帯におけるものであり、湿潤帯の圧損が焼結鉱の操業性、ひいては品質に大きな影響を及ぼしていることがわかる。   FIG. 2 shows the pressure loss and temperature distribution in the charging layer when the highest temperature range of the combustion / melting zone is 200 mm below the surface of the charging layer having a thickness of 600 mm. From this figure, the pressure loss distribution in the charging layer is about 60% in the wet zone, the remaining 40% is in the combustion / melting zone, and the pressure loss in the wet zone is the operability of the sintered ore, As a result, it can be seen that the quality is greatly affected.

ところで、圧損に大きな影響を及ぼす因子として、上記水分の凝縮以外に、焼結時における焼結原料の物理的な収縮がある。すなわち、装入層上層部の焼結が完了した焼結ケーキは、一つの大きな塊となって、燃焼・溶融帯やまだ燃焼が進行していない装入層下部の湿潤帯の上に覆いかぶさる。ここで、上記燃焼・溶融帯は、低融点の溶融相と固相が混合した状態にあるため、上記焼結ケーキの荷重を受けて圧縮されて、下層にいくほど嵩密度が高くなり、通気抵抗が増大する。また、湿潤帯においては、水分が凝縮し、造粒粒子の強度が低下している。そのため、焼結ケーキの荷重によって湿潤帯を構成している造粒粒子が破壊されて、造粒粒子間の空隙が潰されて空気が通り難くなり、通気抵抗が増大する。上記のようにして通気抵抗が増大すると、通風量が減少し、固体燃料の燃焼速度が低下するため、焼結鉱の品質に悪影響を及ぼしたり、生産率を低下させたりすることになる。   By the way, as a factor having a great influence on the pressure loss, there is physical shrinkage of the sintering raw material at the time of sintering, in addition to the condensation of moisture. That is, the sintered cake that has been sintered in the upper part of the charge layer is formed as one large lump and is covered on the combustion / melting zone or the wet zone at the lower part of the charge layer that has not yet been burned. Here, because the combustion / melting zone is in a state where the low melting point melt phase and the solid phase are mixed, it is compressed by receiving the load of the sintered cake, and the bulk density increases as it goes to the lower layer. Resistance increases. In the wet zone, moisture is condensed and the strength of the granulated particles is reduced. Therefore, the granulated particles constituting the wet zone are destroyed by the load of the sintered cake, the gaps between the granulated particles are crushed, making it difficult for air to pass through and increasing the airflow resistance. When the ventilation resistance is increased as described above, the air flow rate is decreased and the combustion speed of the solid fuel is decreased, so that the quality of the sintered ore is adversely affected or the production rate is decreased.

そこで、この問題を解決する技術が数多く開発、提案されている。例えば、特許文献1には、焼結パレットの最下部に床敷鉱層を形成し、その床敷鉱層の上に返鉱層を形成し、さらにその返鉱層の上に返鉱層を含まない焼結原料層を形成して、原料充填層の上層から下層に至る粒度の偏析を大にすることで、通気性を改善する技術が開示されている。また、特許文献2には、焼結パレット上に床敷鉱を装入して床敷層を形成し、上記床敷層に複数の凸状増厚部を設けた後、さらにその床敷層上に焼結用配合原料を装入することによって、焼結ケーキの重さを凸状増厚部で支持し、通気性を確保する技術が開示されている。また、特許文献3には、焼結機のパレットの床に敷かれた床敷層の上に形成された焼結原料層の中層部及び/又は下層部の中で、パレット幅方向に互いに離隔して多数の空洞を設けて焼結原料層の通気を改善するに際し、前記空洞に、焼結原料とは別途に準備した粒状物質を充填することで、スリットによるムラ焼けを防止しつつ、通気性を改善する技術が開示されている。また、特許文献4には、焼結機の焼結パレットに、焼結ケーキを支持するスタンドを設けることで、原料充填層の圧縮を抑制し、通気性を改善する技術が開示されている。   Therefore, many technologies for solving this problem have been developed and proposed. For example, Patent Document 1 discloses a sintering raw material in which a bed deposit ore layer is formed at the bottom of a sintering pallet, a return layer is formed on the bed deposit layer, and a return layer is not included on the return layer. A technique for improving air permeability by forming a layer and increasing the segregation of the particle size from the upper layer to the lower layer of the raw material filled layer is disclosed. Further, in Patent Document 2, a floor covering layer is formed by charging a floor covering ore on a sintered pallet, and a plurality of convex thickening portions are provided on the floor covering layer. A technique is disclosed in which the weight of the sintered cake is supported by the convex thickened portion and the air permeability is ensured by charging the raw material for sintering on the top. Further, Patent Document 3 discloses that in the middle layer portion and / or the lower layer portion of the sintering raw material layer formed on the floor layer laid on the floor of the pallet of the sintering machine, they are separated from each other in the pallet width direction. In order to improve the ventilation of the sintering raw material layer by providing a large number of cavities, by filling the cavities with a granular material prepared separately from the sintering raw material, it is possible to vent A technique for improving the performance is disclosed. Patent Document 4 discloses a technique for suppressing the compression of the raw material packed layer and improving the air permeability by providing a stand for supporting the sintered cake on the sintering pallet of the sintering machine.

特開昭58−061240号公報JP 58-061240 特開平08−246073号公報Japanese Patent Application Laid-Open No. 08-246073 特開2000−213873号公報JP 2000-213873 A 特開平04−168234号公報Japanese Patent Laid-Open No. 04-168234

ところで、焼結原料は、粒径が10mm以下の鉄鉱石(粉鉱石)を主原料とし、これに粒径が5mm以下の返鉱、CaO系副原料、SiO系副原料および固体燃料(コークス等)等を添加してミキサーで混合し、適当量の水分を添加してドラムミキサー等を用いて造粒し、所定の粒径の造粒粒子としたものである。この際、添加される返鉱の量は、全造粒粒子原料の20%程度であるといわれている。 By the way, the sintered raw material is iron ore (powder ore) having a particle size of 10 mm or less as a main raw material, and this is a return ore with a particle size of 5 mm or less, a CaO-based auxiliary material, a SiO 2 -based auxiliary material and a solid fuel (coke). Etc.) and the like are added and mixed with a mixer, and an appropriate amount of water is added and granulated using a drum mixer or the like to obtain granulated particles having a predetermined particle size. At this time, the amount of return ore added is said to be about 20% of the total granulated particle raw material.

しかし、返鉱は、粉鉱石よりも粒度が小さいため造粒性を悪化させる原因となる。したがって、返鉱を造粒粒子の原料として使用する量は、極力少なくすることが望ましい。また、焼結原料中の返鉱量が減少すると、造粒時に添加する水分量も低減できるので、焼結に必要な熱量も削減できるという効果も得られる。   However, returning ore has a smaller particle size than that of fine ore, which causes the granulation property to deteriorate. Therefore, it is desirable to reduce the amount of return ore used as a raw material for granulated particles as much as possible. Moreover, since the amount of moisture added at the time of granulation can also be reduced when the amount of return mineral in the sintering raw material is reduced, an effect that the amount of heat necessary for sintering can also be reduced is obtained.

しかしながら、特許文献1の技術は、返鉱のすべてを床敷鉱の上に返鉱層として敷き詰めることで通気性は若干改善されるものの、原料装入層の収縮を抑制する効果は得られない。また、特許文献2〜4の技術は、いずれも焼結原料中に返鉱のすべてを添加しているため、焼結原料の造粒性を改善できないという問題がある。   However, although the technique of Patent Document 1 slightly improves the air permeability by laying all of the return ore as a return ore layer on the bedding ore, the effect of suppressing the shrinkage of the raw material charge layer cannot be obtained. Moreover, since all of the techniques of Patent Documents 2 to 4 add all of the return to the sintered raw material, there is a problem that the granulation property of the sintered raw material cannot be improved.

本発明は、上記従来技術の問題点に鑑みてなされたものであり、その目的は、焼結原料中に添加する返鉱の量を低減して焼結原料の造粒性を改善するととともに、通気性の低下を抑制することができる焼結鉱の製造方法を提案することにある。   The present invention has been made in view of the above-mentioned problems of the prior art, and its purpose is to improve the granulation property of the sintered raw material by reducing the amount of return to be added to the sintered raw material, The object is to propose a method for producing sintered ore that can suppress a decrease in air permeability.

一般に、焼結原料中に含まれる返鉱の量は20%程度であり、これは、その程度の量の返鉱が発生していることを意味している。したがって、単に返鉱の添加量を低減しただけでは、返鉱が余剰となってしまう。そこで、発明者らは、その余剰となった返鉱を通気性の向上に役立てることを検討した。その結果、上記返鉱の一部を用いて床敷層の上に柱状装入層を形成することで、原料装入層の収縮を抑制してやれば、従来技術が抱える問題点のいずれをも解決し得ることに想到し、本発明を完成させた。   In general, the amount of return ore included in the sintered raw material is about 20%, which means that the amount of return ore is generated. Therefore, simply reducing the amount of return ore added will result in surplus return. Therefore, the inventors studied to make use of the surplus return to improve air permeability. As a result, if the shrinkage of the raw material charging layer is suppressed by forming a columnar charging layer on the flooring layer using a part of the above-mentioned return ore, all of the problems of the prior art are solved. The present invention has been completed.

すなわち、本発明は、循環移動するパレット上に粉鉱石と返鉱、副原料および炭材を含む造粒原料から造粒された造粒粒子を装入して焼結原料装入層を形成し、その装入層表層に点火した後、パレット下方に配設されたウインドボックスで装入層上方の空気を吸引し、装入層内の炭材を燃焼させて焼結鉱を製造する方法において、上記パレットのグレート・バー上に敷かれた床敷層の上に、造粒原料中に添加されるべき粒径が5mm以下の返鉱の一部を用いて、パレットの幅方向に間隔を設けて柱状装入層を形成し、その上に残りの造粒原料から造粒された造粒粒子を装入して装入層を形成することを特徴とする焼結鉱の製造方法である。 That is, the present invention forms a sintered raw material charging layer by charging granulated particles granulated from a granulated raw material including fine ore and return mineral, auxiliary raw material and carbonaceous material on a pallet that moves in a circulating manner. In the method of producing a sintered ore by igniting the surface layer of the charging layer and then sucking the air above the charging layer with a wind box disposed below the pallet and burning the carbonaceous material in the charging layer. , On the floor layer laid on the pallet's great bar, using a part of the returned ore with a particle size of 5 mm or less to be added to the granulated raw material, the interval in the width direction of the pallet It is a method for producing a sintered ore characterized by forming a columnar charge layer and charging a granulated particle granulated from the remaining granulated raw material thereon to form a charge layer .

本発明の焼結鉱の製造方法は、上記柱状装入層の高さを100mm以上、パレット幅方向の間隔を50〜1000mmとすることを特徴とする。   The method for producing a sintered ore according to the present invention is characterized in that the height of the columnar charging layer is 100 mm or more and the interval in the pallet width direction is 50 to 1000 mm.

また、本発明の焼結鉱の製造方法は、上記柱状装入層の形成に用いる返鉱に、FeOを40mass%以上含む粉状材および/または炭材を添加することを特徴とする。 Moreover, the manufacturing method of the sintered ore of this invention is characterized by adding the powdery material and / or carbonaceous material which contain 40 mass% or more of FeO to the return ore used for formation of the said columnar charging layer.

本発明によれば、焼結原料中に添加されるべき返鉱の一部を用いて、パレットの床敷層の上に所定の間隔を開けて柱状装入層を形成するので、焼結原料中に添加する返鉱量が減少して造粒性が改善されるとともに、上記柱状装入層の形成により燃焼・溶融帯および湿潤帯における収縮を抑制して十分な通気性を確保することができるので、高い生産率で焼結鉱を製造することが可能となる。   According to the present invention, the columnar charge layer is formed on the floor layer of the pallet with a predetermined interval using a part of the return ore to be added to the sintering material. The amount of returned ore added to the inside is reduced to improve granulation, and the formation of the above-mentioned columnar charging layer can suppress the shrinkage in the combustion / melting zone and the wet zone to ensure sufficient air permeability. Therefore, it becomes possible to produce sintered ore at a high production rate.

パレット上の原料装入層内の焼結進行過程を模式的に説明する図である。It is a figure which illustrates typically the sintering progress process in the raw material charging layer on a pallet. 焼結時における装入層内の圧損と温度分布を説明する模式図である。It is a schematic diagram explaining the pressure loss and temperature distribution in the charging layer at the time of sintering. 造粒粒子の含水率と、擬似粒子径および通気性との関係を示すグラフである。It is a graph which shows the relationship between the moisture content of a granulated particle, a pseudo particle diameter, and air permeability. 返鉱を用いた柱状装入層が焼結性に及ぼす効果を確認する実験方法を説明する図である。It is a figure explaining the experimental method which confirms the effect which the columnar charging layer using return ore has on sinterability. 返鉱を用いた柱状装入層が焼結性に及ぼす影響を示したグラフである。It is the graph which showed the influence which the columnar charging layer using return ore has on sinterability. 焼結実験後の柱状装入層が未焼成状態にあることを示す写真である。It is a photograph which shows that the columnar charging layer after a sintering experiment is in an unfired state. 実機焼結機において、柱状装入層を形成する方法を説明する模式図である。It is a schematic diagram explaining the method of forming a columnar insertion layer in a real machine sintering machine.

まず、本発明の基本的技術思想について説明する。
前述したように、焼結原料中に添加される返鉱は、一般に、粉鉱石よりも粒度が小さいため、造粒性を悪化させる原因となる。その結果、図3に示したように、鉄分として鉄鉱石100mass%の場合と、それに返鉱を20mass%加えた場合とを比較すると、同じ含水率の場合、造粒粒子の大きさは、鉄鉱石100mass%の方が大きくでき、その分、通気性も向上する。したがって、造粒粒子の原料として返鉱を使用する量は極力少なくすることが望ましいといえる。また、焼結原料中の返鉱量が減少すると、造粒時に添加する水分量も低減できるので、焼結に必要な熱量も低減できるという効果も得られる。
First, the basic technical idea of the present invention will be described.
As described above, the return ore added to the sintered raw material generally has a smaller particle size than the fine ore, which causes the granulation property to deteriorate. As a result, as shown in FIG. 3, when comparing the case of iron ore 100 mass% as the iron content and the case of adding 20 mass% of the return ore to it, the size of the granulated particles is the same in the case of the same moisture content. 100% by mass of stone can be increased, and the air permeability is improved accordingly. Therefore, it can be said that it is desirable to reduce the amount of the return ore used as a raw material for the granulated particles as much as possible. Moreover, since the amount of moisture added at the time of granulation can also be reduced when the amount of return mineral in the sintering raw material is reduced, an effect that the amount of heat necessary for sintering can also be reduced is obtained.

そこで、焼結原料中に添加する返鉱の一部を用いて、内径が290mmφ、高さが400mmの焼結試験鍋の焼結原料装入層内に、柱状の装入層を形成し、焼結原料の収縮量および通気性に及ぼす影響を調査した。
焼結実験は、図4に示したように、通常は造粒粒子の原料中に20mass%添加している返鉱のうちの5mass%あるいは10mass%を除いた原料を混合し、水分を添加して造粒し、焼結原料(造粒粒子)とする一方、使用しなかった5mass%および10mass%の返鉱を用いて、焼結試験鍋の底部床敷層上に、直径が100mmφで、高さがそれぞれ135mmと280mmの柱状装入層を1または2形成し、その後、その試験鍋中に、上記造粒粒子を焼結原料として充填して焼結を行った。なお、比較例として、従来どおり、20mass%の返鉱を焼結原料中に全て添加した例についても調査した。
Therefore, using a part of the return ore added to the sintering raw material, a columnar charging layer is formed in the sintering raw material charging layer of the sintering test pot having an inner diameter of 290 mmφ and a height of 400 mm, The effect of the sintering material on shrinkage and air permeability was investigated.
As shown in FIG. 4, the sintering experiment is performed by mixing raw materials excluding 5 mass% or 10 mass% of the return ore added to 20 mass% in the raw material of granulated particles and adding water. On the bottom floor layer of the sintering test pan, the diameter is 100 mmφ, using 5 mass% and 10 mass% return ore that were not used. One or two columnar charging layers having a height of 135 mm and 280 mm, respectively, were formed, and then the granulated particles were filled as a sintering raw material in the test pot and sintered. In addition, as a comparative example, an example was also investigated in which 20% by mass of return ore was added to the sintered raw material as in the past.

上記焼結実験の結果を図5に示した。この結果から、造粒原料に含まれる返鉱の一部を用いて柱状装入層を形成することにより、焼結時における原料装入層の収縮量が減少し、平均風量が増加していること、しかも、柱状装入層の高さが高いほどその効果が大きいことがわかる。これは、造粒原料への返鉱の添加量削減による造粒性向上効果と、削減した返鉱を用いて形成した柱状装入層による焼結原料装入層の収縮抑制効果によって、通気性が改善された結果によるものと考えられる。   The result of the sintering experiment is shown in FIG. From this result, by forming a columnar charge layer using a part of the return ore contained in the granulated raw material, the shrinkage amount of the raw material charge layer during sintering is reduced, and the average air volume is increased. In addition, it can be seen that the higher the height of the columnar charging layer, the greater the effect. This is because of the effect of improving granulation by reducing the amount of return ore added to the granulated raw material and the effect of suppressing the shrinkage of the sintered raw material charge layer by the columnar charge layer formed using the reduced return ore. This is probably due to the improved results.

また、生産率は、5mass%の返鉱を用いて高さ135mmの柱状装入層を1形成した例では5%の向上が得られていた。したがって、生産性を向上する観点からは、柱状装入層の高さは100mm以上であれば好ましいことがわかる。
一方、10mass%の返鉱を用いて280mm高さの柱状装入層を形成した例では、逆に1%低下している。この原因は、柱状装入層の形成に用いた返鉱の中には、固体燃料をまったく添加していないため、この部分の焼結に必要な熱量が不足し、未焼成となって歩留が低下したことにより、通気性改善による生産性向上効果が打ち消されてしまったためと考えられる。図6は、柱状装入層形成部分を示した写真であり、未焼成となっていることを示している。
また、同じ10mass%の返鉱を用いて高さ135mmの柱状装入層を2形成した例では、生産率が7%向上している。この原因は、高さの低い柱状装入層を2形成したことにより焼結層内の下層部において温度が高温に保たれる時間が延長し、歩留りが向上し、生産性がより向上したものと考えられる。したがって、高さが高くなると、歩留り低下が大きくなるため、上限は装入層厚の3/4程度とするのが好ましい。
Further, the production rate was improved by 5% in an example in which one columnar charging layer having a height of 135 mm was formed by using 5 mass% return ore. Therefore, it can be seen that the height of the columnar charging layer is preferably 100 mm or more from the viewpoint of improving productivity.
On the other hand, in the example in which a columnar charging layer having a height of 280 mm is formed using 10 mass% return ore, it is 1% lower. The reason for this is that, since no solid fuel is added to the return ore used to form the columnar charge layer, the amount of heat necessary to sinter this part is insufficient, resulting in unfired and yield. This is considered to be because the productivity improvement effect due to the improvement in air permeability was canceled due to the decrease in the airflow. FIG. 6 is a photograph showing the columnar charge layer forming portion, showing that it is not fired.
Further, in the example in which two columnar charging layers having a height of 135 mm are formed using the same 10 mass% return ore, the production rate is improved by 7%. This is due to the fact that by forming two columnar charging layers with low height, the time during which the temperature is maintained at a high temperature in the lower layer in the sintered layer is extended, yield is improved, and productivity is further improved. it is conceivable that. Therefore, since the yield decreases as the height increases, the upper limit is preferably set to about 3/4 of the thickness of the charging layer.

なお、上記に説明したように、柱状装入層の形成に用いる返鉱をそのまま用いる場合には、歩留低下を招くことがある。そこで、柱状装入層の焼結性を改善し、歩留りを向上するため、柱状装入層の形成に用いる返鉱中に、低融点溶材または熱源となる粉コークス等の炭材を添加することが好ましい。ここで、上記低融点溶材とは、FeOを40mass%以上含む粉状材をさし、代表的なものとして、ミルスケールや、回転炉床炉の操業で発生したDRI(直接還元鉄)製造時の篩下粉、HBI(ホットブリケットアイアン)の成品篩下粉、製鉄所の集塵ダスト等を挙げることができる。なお、低融点溶材と炭材とを複合添加することは、返鉱の塊成化を促進するのでより好ましい。   As described above, when the return ore used for forming the columnar charge layer is used as it is, the yield may be lowered. Therefore, in order to improve the sinterability of the columnar charge layer and improve the yield, a carbon material such as a low melting point melt or powdered coke as a heat source should be added during the return ore used to form the columnar charge layer. Is preferred. Here, the low-melting-point melting material refers to a powder material containing 40 mass% or more of FeO, and representatively, at the time of manufacturing DRI (direct reduced iron) generated by operation of a mill scale or a rotary hearth furnace. Sieving powder, HBI (hot briquette iron) product sieving powder, steelworks dust collection dust, and the like. In addition, it is more preferable to add the low melting point melting material and the carbon material in combination since the agglomeration of the return ore is promoted.

また、本発明における返鉱を用いた柱状装入層は、上記実験のような柱状である必要はなく、例えば断面形状が三角形、矩形あるいは台形であってもよく、これらをパレットの幅方向に所定の間隔をあけて形成するのが好ましい。また、パレット進行方向には、上記実験のような柱状装入層を、間隔を開けて設けてもよいし、衝立状に連続して設けてもよい。本発明では、それらを総称して「柱状装入層」ということとする。   Further, the columnar charging layer using the return ore according to the present invention does not need to be a columnar shape as in the above-described experiment. For example, the cross-sectional shape may be a triangle, a rectangle or a trapezoid, and these may be arranged in the width direction of the pallet. It is preferable to form them at a predetermined interval. In the pallet traveling direction, the columnar charging layers as in the above-described experiment may be provided at intervals or continuously in a partition shape. In the present invention, these are collectively referred to as a “columnar charge layer”.

また、上記各柱状装入層を形成するパレット幅方向の間隔は、最近接間距離が50mm以上1000mm以下とするのが好ましい。50mm未満では、柱状装入層形成の効果が飽和するばかりでなく、柱状装入層形成に必要な返鉱が大量に必要となってしまう。一方、1000mmを超えると、柱状装入層の所期した効果が得られなくなるからである。好ましくは50〜500mmの範囲である。なお、柱状装入層の断面幅は、柱状装入層が形成できる幅であればよく、特に制限はないが、50〜100mm程度の範囲が好ましい。   Moreover, as for the space | interval of the pallet width direction which forms each said columnar insertion layer, it is preferable that distance between nearest neighbors shall be 50 mm or more and 1000 mm or less. If it is less than 50 mm, not only the effect of forming the columnar charging layer is saturated, but also a large amount of return ore necessary for forming the columnar charging layer is required. On the other hand, if it exceeds 1000 mm, the desired effect of the columnar charging layer cannot be obtained. Preferably it is the range of 50-500 mm. In addition, the cross-sectional width of the columnar charging layer is not particularly limited as long as the columnar charging layer can be formed, but a range of about 50 to 100 mm is preferable.

パレット幅が5.5mの実機焼結機において、表1に示した配合割合(返鉱の配合率が21mass%)の焼結原料(造粒原料)を用いて、下記の焼結実験を行った。
実験は、図7に示したように、実機焼結機の給鉱側に設置されている床敷層用の返鉱を供給する床敷層用ホッパーと、焼結原料(造粒粒子)を供給する原料ホッパーとの間に、柱状装入層用ホッパーを新たに設置し、床敷層用ホッパーでパレットのグレート・バー(火格子)上に返鉱を供給して床敷層を形成した後、その上に柱状装入層用ホッパーから造粒粒子中に添加すべき返鉱の一部を床敷層の上に間隔をあけて種々の柱状装入層を形成し、さらにその上に、柱状装入層の形成に用いた返鉱の残りを含む造粒原料を造粒して得た造粒粒子を焼結原料ホッパーから供給して、パレット上に厚さ540mmの原料装入層を形成した後、常法にしたがって焼結を行った。
In the actual machine sintering machine with a pallet width of 5.5 m, the following sintering experiment was conducted using the sintering raw material (granulating raw material) having the mixing ratio shown in Table 1 (the mixing ratio of the return ore being 21 mass%). It was.
In the experiment, as shown in FIG. 7, a floor layer hopper that supplies return for floor layer installed on the supply side of the actual sintering machine, and a sintering raw material (granulated particles) A columnar loading layer hopper was newly installed between the raw material hopper to be supplied, and the flooring layer was formed by supplying the ore back onto the pallet's great bar (grate) with the flooring layer hopper. After that, various columnar charge layers are formed on the floor layer by separating a part of the ore to be added to the granulated particles from the columnar charge layer hopper on the floor layer. The granulated particles obtained by granulating the granulated raw material containing the remainder of the return ore used for forming the columnar charged layer are supplied from the sintered raw material hopper, and the raw material charged layer having a thickness of 540 mm is placed on the pallet. After forming, sintering was performed according to a conventional method.

Figure 0005703715
Figure 0005703715

なお、床敷層上に形成した柱状装入層は、図7に示したように、パレット断面でみた形状が矩形で、パレット進行方向に延びた衝立状とし、上記矩形の幅を100mm一定とし、高さと、パレット幅方向の形成間隔を表2に示したように種々に変化させた。
また、焼結実験では、焼結原料装入層の通気性指数JPUと焼結鉱の生産率を求めて、柱状装入層の効果を評価した。
ここで、上記通気性指数JPUとは、ボイスの式に準拠した下記式;
P=F/A(H/S)
但し、P:通気度(JPU)、A:試料筒ロストル部断面積または焼結機面積(cm)、F:通過風量(dl/min)、H:原料装入高さ(cm)、S:負圧(cmAq)、n:0.6
より求められる値であり、JPUの値が高い程、通気性が良好であることを示している。
また、生産率は、焼結に要した時間と、焼結鉱の成品歩留り(焼結試験で得られた焼結ケーキを破砕し、篩い分けしたときの粒径が5mm以上の粒子の質量%)から求めた。
As shown in FIG. 7, the columnar loading layer formed on the floor layer is rectangular in shape when viewed from the pallet cross section and has a partition shape extending in the pallet traveling direction, and the rectangular width is constant at 100 mm. The height and the formation interval in the pallet width direction were variously changed as shown in Table 2.
In the sintering experiment, the permeability index JPU of the sintered raw material charging layer and the production rate of the sintered ore were obtained to evaluate the effect of the columnar charging layer.
Here, the air permeability index JPU is the following formula based on the voice formula;
P = F / A (H / S) n
However, P: Air permeability (JPU), A: Sample cylinder cross-sectional area or sintering machine area (cm 2 ), F: Air flow rate (dl / min), H: Raw material charging height (cm), S : Negative pressure (cmAq), n: 0.6
This is a more required value, and the higher the JPU value, the better the air permeability.
The production rate is the time required for sintering and the yield of sintered ore (mass% of particles having a particle size of 5 mm or more when the sintered cake obtained in the sintering test is crushed and sieved. )

Figure 0005703715
Figure 0005703715

上記試験の結果を表2中に併記した。表2から、本発明の条件に適合する条件で柱状装入層を形成した発明例1〜4は、柱状装入層を形成しなかった従来例と比較して、通気性が2.8%以上向上し、生産率も2.0%以上改善されている。これは、柱状装入層の形成によって造粒原料中に含まれる返鉱の比率が低下し、造粒性が向上した効果と、および、形成した柱状装入層の支柱作用によって、焼結時における原料装入層の収縮が抑制された効果の相乗効果によるものと考えられる。また、柱状装入層の高さあるいは間隔が本発明の好適条件ではない発明例5〜7の場合には、柱状装入層の支柱的作用が十分に得られないため、通気性、生産率が発明例1〜4より若干低下しているが、従来例より良好な結果が得られている。   The results of the above test are also shown in Table 2. From Table 2, the inventive examples 1 to 4 in which the columnar charging layer was formed under the conditions suitable for the conditions of the present invention had an air permeability of 2.8% compared to the conventional example in which the columnar charging layer was not formed. The production rate has been improved by 2.0% or more. This is because the ratio of return ore contained in the granulated raw material is reduced by the formation of the columnar charging layer, the effect of improving the granulation property, and the column action of the formed columnar charging layer during sintering. This is considered to be due to a synergistic effect of the effect of suppressing the shrinkage of the raw material charging layer. Further, in the case of Invention Examples 5 to 7 in which the height or interval of the columnar charging layer is not a preferable condition of the present invention, the columnar charging layer can not sufficiently obtain the columnar action, so the air permeability and the production rate. Is slightly lower than Invention Examples 1 to 4, but better results than the conventional examples are obtained.

Claims (3)

循環移動するパレット上に粉鉱石と返鉱、副原料および炭材を含む造粒原料から造粒された造粒粒子を装入して焼結原料装入層を形成し、その装入層表層に点火した後、パレット下方に配設されたウインドボックスで装入層上方の空気を吸引し、装入層内の炭材を燃焼させて焼結鉱を製造する方法において、上記パレットのグレート・バー上に敷かれた床敷層の上に、造粒原料中に添加されるべき粒径が5mm以下の返鉱の一部を用いて、パレットの幅方向に間隔を設けて柱状装入層を形成し、その上に残りの造粒原料から造粒された造粒粒子を装入して装入層を形成することを特徴とする焼結鉱の製造方法。 A sintered raw material charging layer is formed by charging granulated particles granulated from a granulated raw material including fine ore, return mineral, auxiliary raw material and carbonaceous material on a circulating moving pallet. In the method of producing sintered ore by sucking the air above the charging layer with a wind box disposed below the pallet and burning the carbonaceous material in the charging layer, A columnar charge layer with a gap in the width direction of the pallet, using a part of the returned ore with a particle size of 5 mm or less to be added to the granulated raw material on the floor layer laid on the bar And a charged layer is formed by charging the granulated particles granulated from the remaining granulated raw material thereon. 上記柱状装入層の高さを100mm以上、パレット幅方向の間隔を50〜1000mmとすることを特徴とする請求項1に記載の焼結鉱の製造方法。 2. The method for producing a sintered ore according to claim 1, wherein the height of the columnar charging layer is 100 mm or more and the interval in the pallet width direction is 50 to 1000 mm. 上記柱状装入層の形成に用いる返鉱に、FeOを40mass%以上含む粉状材および/または炭材を添加することを特徴とする請求項1または2に記載の焼結鉱の製造方法。 The method for producing a sintered ore according to claim 1 or 2, wherein a powdery material and / or a carbonaceous material containing 40 mass% or more of FeO is added to the return ore used for forming the columnar charge layer.
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