JP4031108B2 - Reduction method of reduced iron powder - Google Patents
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【０００１】
【発明の属する技術分野】
本発明は炭材内装ペレット及び還元鉄製造方法に関し、詳細には、炭材と酸化鉄を含む炭材内装ペレットを加熱還元することにより還元鉄を製造する直接製鉄法において、酸化鉄の還元工程の生産性を改善することのできる炭材内装ペレットと上記炭材内装ペレットを用いた還元鉄の製造方法に関するものである。
【０００２】
【従来の技術】
還元鉄の製造方法としてはミドレックス法が知られており、この方法によれば天然ガスから生成した還元性ガスを羽口から吹込み、シャフト炉中を上昇させることによって、炉内に充填された鉄鉱石や酸化鉄ペレットを還元して還元鉄を得ることができる。但し、この製造方法では、燃料としてコストの高い天然ガスを大量に供給する必要がある。
【０００３】
そこで近年では、上記天然ガスに代えて比較的安価な石炭を還元剤として使用することのできる還元鉄製造プロセスが注目されている。例えば米国特許第3,443,931 号には、粉鉱石と炭材とを混合してペレット化し、高温雰囲気下で加熱還元することにより還元鉄を製造するプロセスが記載されている。この方法によれば、石炭ベースであることの他にも、粉鉱石を直接使用できること、高速還元が可能であること、製品中の炭素含有量を調節することができる等の利点を有している。但し、このプロセスでは高温反応炉における上面からの輻射熱によりペレットを加熱しているので原料層の高さが制限され、従って製品の生産性を向上させるには、還元反応の反応速度自体を高める必要がある。
【０００４】
還元反応の反応速度を高める方法としては、還元時の処理温度を上昇させることが考えられるが、処理温度を上昇させるにあたり、ペレットの表面温度が高くなり過ぎるとペレット表面が溶融して、炉内での固着や炉体損傷の問題を引き起こす。
【０００５】
従って、高温反応炉で炭材内装ペレットを加熱還元することにより還元鉄を製造する上記プロセスにおいては、還元反応を促進して生産性の向上を図ることのできる還元鉄の製造方法の開発が期待されている。
【０００６】
【発明が解決しようとする課題】
本発明は上記事情に着目してなされたものであって、酸化鉄の還元反応を促進することができる炭材内装ペレットと、上記炭材内装ペレットを用いた生産性の高い還元鉄製造方法を提供しようとするものである。
【０００７】
【課題を解決するための手段】
上記課題を解決した本発明とは、炭材と酸化鉄からなる炭材内装ペレットであって、上記炭材の軟化溶融時の最高流動度が０．４以上であることを要旨とするものであり、上記最高流動度が０．８以上であると望ましい。
【０００８】
また前記炭材は、単一種の炭材であってもよく、複数種の炭材を配合して上記流動度を０．４以上（望ましくは０．８以上）に調整したものであってもよい。
【０００９】
本発明に係る上記炭材内装ペレットは、熱伝導性に優れているので、これを用いて還元鉄を製造すれば生産性の向上が実現できる。
【００１０】
本発明において、炭材とは、石炭，コークス，石油コークス，ピッチ，タール等の炭素含有物質をいうものであり、軟化溶融時の最高流動度が０．４以上（望ましくは０．８以上）のものであれば、単一種の炭材であってもよく、複数種の炭材の混合物であっても良い。
【００１１】
尚、本発明において最高流動度とは、ＪＩＳ Ｍ８８０１で規定された値であり、流動度計であるジースラー・プラスト・メーター(Gieseler Plasto meter) を用いて測定された値である。
【００１２】
【発明の実施の形態】
還元鉄の製造方法において、その生産性を高めるべく炭材内装ペレットの還元速度を高めることを目的として還元炉温度を上げる場合に、ペレット内部における伝熱可能エネルギーの限界以上に熱エネルギーを供給すると、ペレットの表面温度が高くなり過ぎ、ペレットが溶融して炉内での固着や炉体損傷の問題を引き起こす。即ち、炭材内装ペレットの還元速度は、ペレット内の伝熱に律速されるものであり、生産性向上のためにはペレット内における熱伝導性の改善が不可欠である。本発明者らは、炭材内装ペレットの様な多孔質体の熱伝導性を高めるためには粒子間の接触面積の増大が有効であり、その為には軟化溶融時の流動性の高い炭材を炭材内装ペレットに用いれば良いことを突き止め、本発明に想到した。
【００１３】
本発明の製造方法では、還元に先行する乾留反応において、造粒物内部の酸化鉄粒子が形成する空隙を軟化溶融した炭材が充填することにより、酸化鉄粒子が炭素質で連結されて熱伝導率が向上すると共に酸化鉄と炭素質の接触面積が増大することによって還元が促進されるものである。より詳細に説明すると以下の通りである。
【００１４】
還元が始まるまでの昇温過程において、炭材は約３００〜５００℃で軟化溶融し、５００℃以上で固化する。この軟化溶融時の流動性が高いとペレット内空隙を炭材が容易に移動し、固化した後の固体炭素質が酸化鉄同士を連結する。この炭素による酸化鉄の連結構造がペレット内部における接触面積を増大し、炭材内装ペレットの熱伝導性を向上させるものである。
【００１５】
また炭素質還元剤である炭材と酸化鉄の接触面積の増大は、固体炭素による直接還元を促進するという作用も有する。
【００１６】
更に、高流動性の炭材を用いると固化後の炭素質の比表面積が高くなるのでガス化反応が活発に起こり、ペレット内部でのＣＯ分圧が高められるので、ＣＯによるガス還元も促進される。
【００１７】
本発明に用いる炭材としては、石炭，コークス，石油コークス，ピッチ，タール等の炭素含有物質を用いることができ、軟化溶融時の最高流動度が０．４以上であれば、炭材は単体であっても、混合物であってもよい。尚、上記最高流動度は０．８以上であれば望ましく、１．０以上であるとより望ましい。
【００１８】
上記炭材の配合量は、用いる酸化鉄及び炭材の種類に応じて、酸化鉄の還元に必要な量を配合すれば良いが、通常は原料酸化鉄に対して１０〜３０重量％程度である。
【００１９】
尚、製品還元鉄は還元がほぼ終了した後に、金属鉄が焼結することにより強度が高まる。生産性の向上を目的として高温反応炉内における滞留時間を短くしようとする場合、還元反応時の履歴温度が低いと焼結不良を起こして、還元鉄強度が十分高くならず、還元炉から排出する際などのハンドリング工程で破壊粉化が進行し、製品歩留りが低下する。本発明の製造方法によれば還元が促進されて金属化後の履歴時間を延ばすことができ、焼結も促進されて製品還元鉄の強度が増大し、還元炉排出時の粉化を抑制することができる。
【００２０】
流動性の異なる１２種類の炭素質還元剤Ａ〜Ｌを炭材として含有する炭材内装ペレットを用いて９分間の還元時間で還元鉄を製造した場合の最高流動度と製品粉率の関係を図１に示す。尚、上記製品粉率とは、還元炉からの排出時ハンドリング工程での粉化された直径６ｍｍ以下の粉体の割合である。最高流動度が低い炭材（Ａ，Ｂ，Ｃ）を用いた場合には粉率が高く、最高流動度が高い（０．４以上）の還元剤を用いた場合には、粉率が低下して製品歩留が向上するものであり、更に最高流動度が０．８以上であればより望ましいことが分かる。
【００２１】
図２に、流動度が異なる５種類の炭材Ａ，Ｃ，Ｅ，Ｈ，Ｉについて、１３００℃で加熱した際の加熱時間とペレット中心部の温度の関係を示す。炭材の流動性が高い方（炭材Ｈ，Ｉ）が炭材の流動性が低いもの（炭材Ａ，Ｃ）に比較して１３００℃に到達する時間は短いことが分かる。また還元反応は約８００℃から始まることから昇温過程の温度履歴も重要であり、高流動性の炭材は（特に炭材Ａに対して）ペレット内部の昇温も速いことが分かる。尚、このときの還元過程におけるペレット断面の組織観察から、流動性の高い場合には酸化鉄粒子の固体炭素質による連結構造が形成されることが確認された。
【００２２】
また最高流動度が０．４未満であるオイルコークス等の炭材であっても、高流動性の石炭やタール，ピッチ，または水素供与性を有する有機溶剤（例えばベンゼン，アニリンなどの芳香族化合物）等を添加することによって最高流動度を０．４以上（望ましくは０．８以上）になる様に調整すれば、本発明に利用することが可能である。
【００２３】
非流動性の還元剤であるオイルコークスに高流動性還元剤である石炭Ｈを混合した場合の実験結果を表１及び図３に示す。
【００２４】
【表１】
混合還元剤の最高流動度の実測値は各還元剤の最高流動度の配合率による加重平均よりも若干小さいものの任意の値に調整できること、更に混合還元剤においても単一還元剤と同様に粉率低減効果が得られることが分かる。
【００２６】
尚、還元剤として石炭を用いる場合には、流動性が高い程、揮発分含有量が多いことが一般的であるが、揮発分含有量の多い石炭を用いると、揮発分の放出過程に伴うバースティングの問題を生じる。揮発分とは、炭材中に含まれるＣＨ4,Ｈ2 ，ＣＯ，ＣＯ2 ，水分等であり、炭材中の揮発分含有量が増加するのに伴い、還元反応は促進されるが多過ぎると、還元途中でペレットが破裂（バースティング）するものである。ペレットの破裂を抑制するには、炭材１ｇ当たりの揮発分含有量が0.026 mol 以下の範囲内で揮発分含有量の多い炭材を還元剤とすることが望ましく、一方還元反応を促進させる上で、揮発分含有量は0.020mol／炭材１ｇ程度とすることが望ましい。
【００２７】
従って、高揮発分・高流動性の石炭に低揮発分・低流動性の石炭を混合して、揮発分がバースティング限界以下となり、流動性が０．４以上（望ましくは０．８以上）となるように還元剤を配合することが望ましい。
【００２８】
また本発明に係る還元鉄の製造方法を実施するにあたっては、通常の高温反応炉を用いれば良く、ロータリーハース炉やトンネル炉等、炭材内装ペレットを所定の温度まで加熱・保持することが可能な全ての高温反応炉を適用することができる。
【００２９】
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・後記の主旨に徴して設計変更することはいずれも本発明の技術的範囲に含まれるものである。
【００３０】
【実施例】
実施例１
石炭やオイルコークス等、最高流動度の異なる１２種類（Ａ〜Ｌ）の炭素質還元剤を炭材として用い、ヘマタイト鉱石（Ｔ．ＦＥ＝６８％）１００部に、単一銘柄の炭材２７部と、バインダーとしてベントナイト１部及び有機系バインダー０．１部を加えて、球形に成型した炭材内装ペレットを作製した。
【００３１】
具体的には、鉄鋼石，炭材，バインダーを貯留している原料槽から所定量を計量して、原料ミキサにより混合し、造粒装置にて粒状に成形して、乾燥機を通過させることによって成形した。ペレットは、ロータリーハース炉に導入し１３００℃で９分間加熱還元して冷却した後、製品として排出した。
【００３２】
結果は図１に示す。最高流動度が０．４未満の炭材Ａ〜Ｃでは粉率が１０％以上であったのに対し、最高流動度が０．４以上の炭材Ｄ〜Ｌでは粉率が７％以下となっており、最高流動度が０．８以上の炭材Ｄ〜ＪとＬでは粉率が５％以下となっている。
【００３３】
実施例２
次に、最高流動度が約０．３である炭材Ｃと、約２．５である炭材Ｇを用いて、還元温度１３００℃における還元時間と製品還元鉄の粉率の関係を調べた。結果は図４に示す。
【００３４】
図４から分かる様に、炭材Ｃの場合、同じ還元温度では粉率を５％まで低減するには１１分間の還元が必要である。一方、炭材Ｇの場合には、７分間程度の還元時間で粉率は５％以下となっている。但し、金属化率を９０％以上とするには９分間程度の還元時間が必要である。従って、両者の生産性を比較すると、本発明によれば、２０％程度生産性が改善されることとなる。
【００３５】
【発明の効果】
本発明は以上の様に構成されているので、酸化鉄の還元反応を促進することができる炭材内装ペレットと、上記炭材内装ペレットを用いた生産性の高い還元鉄製造方法が提供できることとなった。
【図面の簡単な説明】
【図１】還元剤の流動性と製品中の粉率の関係を示すグラフである。
【図２】各種ペレットの加熱時間と中心部の温度の関係を示すグラフである。
【図３】流動性の異なる２種類の還元剤の配合による流動度と製品粉率の関係を示すグラフである。
【図４】製品粉率と還元時間の関係を示すグラフである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a carbonaceous material-containing pellet and a method for producing reduced iron, and in particular, in a direct iron manufacturing method for producing reduced iron by heating and reducing a carbonaceous material-containing pellet containing carbonaceous material and iron oxide, a reduction process of iron oxide. It is related with the manufacturing method of reduced iron using the carbonaceous material interior pellet which can improve productivity, and the said carbonaceous material interior pellet.
[0002]
[Prior art]
As a method for producing reduced iron, the Midrex method is known. According to this method, reducing gas generated from natural gas is blown from the tuyere and is raised in the shaft furnace to fill the furnace. Reduced iron can be obtained by reducing iron ore and iron oxide pellets. However, in this manufacturing method, it is necessary to supply a large amount of high-cost natural gas as fuel.
[0003]
Therefore, in recent years, attention has been paid to a reduced iron production process in which relatively inexpensive coal can be used as a reducing agent instead of the natural gas. For example, U.S. Pat. No. 3,443,931 describes a process for producing reduced iron by mixing powdered ore and a carbonaceous material into pellets and heating and reducing in a high temperature atmosphere. According to this method, in addition to being based on coal, there are advantages such as being able to directly use fine ore, being capable of high-speed reduction, and being able to adjust the carbon content in the product. Yes. However, in this process, the pellets are heated by the radiant heat from the upper surface in the high temperature reactor, so the height of the raw material layer is limited. Therefore, in order to improve the productivity of the product, it is necessary to increase the reaction rate of the reduction reaction itself. There is.
[0004]
As a method for increasing the reaction rate of the reduction reaction, it is conceivable to increase the treatment temperature during the reduction. However, when the treatment temperature is increased, if the surface temperature of the pellet becomes too high, the pellet surface will melt, Cause problems of sticking and furnace damage.
[0005]
Therefore, in the above-mentioned process for producing reduced iron by heating and reducing carbonaceous material-containing pellets in a high-temperature reactor, development of a method for producing reduced iron that can promote reduction reaction and improve productivity is expected. Has been.
[0006]
[Problems to be solved by the invention]
This invention was made paying attention to the said situation, Comprising: The carbonaceous material interior pellet which can accelerate | stimulate the reduction reaction of iron oxide, and the reduced iron manufacturing method with high productivity using the said carbonaceous material interior pellet It is something to be offered.
[0007]
[Means for Solving the Problems]
The present invention that has solved the above problems is a carbon material-containing pellet made of carbon material and iron oxide, and the gist is that the maximum fluidity during softening and melting of the carbon material is 0.4 or more. It is desirable that the maximum fluidity is 0.8 or more.
[0008]
Further, the carbon material may be a single type of carbon material, or a mixture of a plurality of types of carbon material and the fluidity adjusted to 0.4 or more (preferably 0.8 or more). Good.
[0009]
Since the carbonaceous material-incorporated pellets according to the present invention are excellent in thermal conductivity, productivity can be improved if reduced iron is produced using the pellets.
[0010]
In the present invention, the carbon material refers to a carbon-containing material such as coal, coke, petroleum coke, pitch, tar, etc., and the maximum fluidity during softening and melting is 0.4 or more (preferably 0.8 or more). As long as it is a thing, it may be a single type of carbon material or a mixture of a plurality of types of carbon material.
[0011]
In the present invention, the maximum fluidity is a value defined by JIS M8801, and is a value measured using a Gieseler Plasto meter which is a rheometer.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
In the method for producing reduced iron, when the reduction furnace temperature is increased for the purpose of increasing the reduction rate of the carbonaceous material-containing pellets in order to increase the productivity, if heat energy is supplied beyond the limit of heat transferable energy inside the pellets The surface temperature of the pellets becomes too high, and the pellets melt and cause problems such as sticking in the furnace and damage to the furnace body. That is, the reduction rate of the carbonaceous material-containing pellets is limited by the heat transfer in the pellets, and in order to improve productivity, it is essential to improve the thermal conductivity in the pellets. In order to increase the thermal conductivity of a porous material such as a carbonaceous material-containing pellet, the present inventors have effectively increased the contact area between the particles. The present inventors have found out that the material may be used for the carbonaceous material-incorporated pellets and have arrived at the present invention.
[0013]
In the production method of the present invention, in the carbonization reaction prior to the reduction, the voids formed by the iron oxide particles inside the granulated product are filled with the softened and melted carbonaceous material so that the iron oxide particles are connected with carbonaceous material and heated. Reduction is accelerated by improving the conductivity and increasing the contact area between iron oxide and carbonaceous material. This will be described in more detail as follows.
[0014]
In the temperature rising process until the reduction starts, the carbonaceous material softens and melts at about 300 to 500 ° C. and solidifies at 500 ° C. or higher. When the fluidity at the time of softening and melting is high, the carbonaceous material easily moves through the voids in the pellet, and the solid carbonaceous material after solidification connects the iron oxides. This connection structure of iron oxide by carbon increases the contact area inside the pellet, and improves the thermal conductivity of the carbonaceous material-containing pellet.
[0015]
In addition, an increase in the contact area between the carbonaceous material, which is a carbonaceous reducing agent, and iron oxide also has an effect of promoting direct reduction by solid carbon.
[0016]
In addition, when a highly fluid carbon material is used, the specific surface area of the carbonaceous material after solidification becomes high, so that the gasification reaction occurs actively, and the CO partial pressure inside the pellet is increased, so that gas reduction by CO is also promoted. The
[0017]
As the carbon material used in the present invention, carbon-containing materials such as coal, coke, petroleum coke, pitch, tar, etc. can be used, and if the maximum fluidity at the time of softening and melting is 0.4 or more, the carbon material is a simple substance. Or a mixture. The maximum fluidity is desirably 0.8 or more, and more desirably 1.0 or more.
[0018]
The blending amount of the carbonaceous material may be blended in an amount necessary for the reduction of iron oxide depending on the type of iron oxide and carbonaceous material to be used, but is usually about 10 to 30% by weight with respect to the raw iron oxide. is there.
[0019]
In addition, the strength of the product reduced iron is increased by sintering the metallic iron after the reduction is almost completed. When trying to shorten the residence time in the high-temperature reactor for the purpose of improving productivity, if the history temperature during the reduction reaction is low, sintering failure will occur and the reduced iron strength will not be sufficiently high and will be discharged from the reduction furnace. In the handling process such as when destructive, pulverization proceeds and the product yield decreases. According to the production method of the present invention, reduction is promoted and the history time after metallization can be extended, sintering is also promoted, the strength of the product reduced iron is increased, and pulverization at the time of discharge in the reduction furnace is suppressed. be able to.
[0020]
The relationship between the maximum fluidity and the product powder ratio when reducing iron is produced in a reduction time of 9 minutes using carbonaceous material-containing pellets containing 12 types of carbonaceous reducing agents A to L having different fluidity as carbonaceous materials. As shown in FIG. In addition, the said product powder rate is the ratio of the powder of diameter 6mm or less pulverized in the handling process at the time of discharge | emission from a reduction furnace. When using carbonaceous materials (A, B, C) with low maximum fluidity, the powder rate is high, and when using a reducing agent with high maximum fluidity (0.4 or higher), the powder rate decreases. Thus, the product yield is improved, and it is further desirable that the maximum fluidity is 0.8 or more.
[0021]
FIG. 2 shows the relationship between the heating time at the time of heating at 1300 ° C. and the temperature at the center of the pellet for five types of carbon materials A, C, E, H, and I having different fluidities. It can be seen that the time when the carbon material has higher fluidity (carbon materials H and I) reaches 1300 ° C. is shorter than that when the carbon material has lower fluidity (carbon materials A and C). In addition, since the reduction reaction starts at about 800 ° C., the temperature history of the temperature raising process is also important, and it can be seen that the high fluidity carbonaceous material (particularly with respect to the carbonaceous material A) has a fast temperature rise inside the pellet. In addition, from the observation of the structure of the pellet cross-section during the reduction process at this time, it was confirmed that when the fluidity is high, a connection structure of solid iron oxide particles is formed.
[0022]
In addition, even in the case of carbon materials such as oil coke having a maximum fluidity of less than 0.4, high-fluidity coal, tar, pitch, or hydrogen-donating organic solvents (for example, aromatic compounds such as benzene and aniline) If the maximum fluidity is adjusted to 0.4 or more (preferably 0.8 or more) by adding), etc., it can be used in the present invention.
[0023]
Table 1 and FIG. 3 show the experimental results when oil coke, which is a non-flowing reducing agent, is mixed with coal H, which is a high-flowing reducing agent.
[0024]
[Table 1]
The actual value of the maximum fluidity of the mixed reducing agent can be adjusted to an arbitrary value that is slightly smaller than the weighted average of the maximum fluidity blending ratio of each reducing agent. It can be seen that a rate reduction effect is obtained.
[0026]
In addition, when using coal as a reducing agent, it is common that the higher the fluidity, the higher the volatile content. However, when coal with a higher volatile content is used, the volatile matter is released. Causes bursting problems. Volatiles are CH 4 , H 2 , CO, CO 2 , moisture, etc. contained in the carbonaceous material, and the reduction reaction is promoted as the volatile content in the carbonaceous material increases. If too much, the pellet bursts (bursting) during the reduction. In order to suppress the bursting of pellets, it is desirable to use a carbonaceous material with a high volatile content within a range of 0.026 mol or less per gram of carbonaceous material as a reducing agent, while promoting the reduction reaction. Thus, the volatile content is preferably about 0.020 mol / g of carbonaceous material.
[0027]
Therefore, by mixing low volatile matter / low fluidity coal with high volatile matter / high fluidity coal, the volatile matter is below the bursting limit and the fluidity is 0.4 or more (preferably 0.8 or more). It is desirable to blend a reducing agent so that
[0028]
In carrying out the method for producing reduced iron according to the present invention, an ordinary high-temperature reactor may be used, and carbonaceous material-containing pellets such as a rotary hearth furnace and a tunnel furnace can be heated and held to a predetermined temperature. All high temperature reactors can be applied.
[0029]
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 any design changes in accordance with the gist of the preceding and following descriptions are technical aspects of the present invention. It is included in the range.
[0030]
【Example】
Example 1
Twelve kinds (A to L) of carbonaceous reducing agents having different maximum fluidity such as coal and oil coke are used as the carbonaceous material, and 100 parts of hematite ore (T.FE = 68%) are mixed with a single brand of carbonaceous material 27 And 1 part of bentonite and 0.1 part of an organic binder as a binder were added to produce a carbonaceous material-containing pellet formed into a spherical shape.
[0031]
Specifically, a predetermined amount is weighed from a raw material tank storing steel stone, carbonaceous material, and binder, mixed by a raw material mixer, formed into granules with a granulator, and passed through a dryer. Molded by The pellets were introduced into a rotary hearth furnace, heated and reduced at 1300 ° C. for 9 minutes, cooled, and then discharged as a product.
[0032]
The results are shown in FIG. In the carbon materials A to C having a maximum fluidity of less than 0.4, the powder rate was 10% or more, whereas in the carbon materials D to L having a maximum fluidity of 0.4 or more, the powder rate was 7% or less. In the carbon materials DJ and L having a maximum fluidity of 0.8 or more, the powder rate is 5% or less.
[0033]
Example 2
Next, using a carbon material C having a maximum fluidity of about 0.3 and a carbon material G having a maximum fluidity of about 2.5, the relationship between the reduction time at a reduction temperature of 1300 ° C. and the powder rate of the product reduced iron was examined. . The results are shown in FIG.
[0034]
As can be seen from FIG. 4, in the case of the carbon material C, reduction for 11 minutes is necessary to reduce the powder rate to 5% at the same reduction temperature. On the other hand, in the case of the carbon material G, the powder rate is 5% or less in a reduction time of about 7 minutes. However, a reduction time of about 9 minutes is required to make the metallization rate 90% or more. Therefore, comparing the productivity of both, according to the present invention, the productivity is improved by about 20%.
[0035]
【The invention's effect】
Since the present invention is configured as described above, it is possible to provide a carbonaceous material-containing pellet that can promote the reduction reaction of iron oxide, and a highly productive method for producing reduced iron using the carbonaceous material-containing pellet. became.
[Brief description of the drawings]
FIG. 1 is a graph showing the relationship between the flowability of a reducing agent and the powder rate in a product.
FIG. 2 is a graph showing the relationship between the heating time of various pellets and the temperature at the center.
FIG. 3 is a graph showing the relationship between the fluidity and the product powder rate by blending two kinds of reducing agents having different fluidity.
FIG. 4 is a graph showing the relationship between product powder rate and reduction time.
Claims (3)
軟化溶融時の最高流動度が０．４以上の炭素質還元剤を用いて還元鉄の粉化を抑えることを特徴とする還元鉄の粉化抑制方法。In producing reduced iron using carbonaceous reducing agent-incorporated pellets consisting of a carbonaceous reducing agent and iron oxide,
A method for suppressing reduced iron pulverization, characterized by suppressing pulverization of reduced iron using a carbonaceous reducing agent having a maximum fluidity of 0.4 or more during softening and melting.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17638098A JP4031108B2 (en) | 1997-06-30 | 1998-06-23 | Reduction method of reduced iron powder |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9-174732 | 1997-06-30 | ||
| JP17473297 | 1997-06-30 | ||
| JP17638098A JP4031108B2 (en) | 1997-06-30 | 1998-06-23 | Reduction method of reduced iron powder |
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| JP4031108B2 true JP4031108B2 (en) | 2008-01-09 |
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| WO2009008270A1 (en) * | 2007-07-10 | 2009-01-15 | Kabushiki Kaisha Kobe Seiko Sho | Carbon composite iron oxide briquette and process for producing the same |
| KR101063328B1 (en) * | 2009-04-02 | 2011-09-07 | 주식회사 포스코 | Steelmaking additives and preparation method thereof |
| JP2012062505A (en) * | 2010-09-14 | 2012-03-29 | Kobe Steel Ltd | Method for manufacturing agglomerate |
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