JP2005200672A - Dust compact for reduction treatment - Google Patents
Dust compact for reduction treatment Download PDFInfo
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- JP2005200672A JP2005200672A JP2004005422A JP2004005422A JP2005200672A JP 2005200672 A JP2005200672 A JP 2005200672A JP 2004005422 A JP2004005422 A JP 2004005422A JP 2004005422 A JP2004005422 A JP 2004005422A JP 2005200672 A JP2005200672 A JP 2005200672A
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- 239000000428 dust Substances 0.000 title claims abstract description 86
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 96
- 229910052742 iron Inorganic materials 0.000 claims abstract description 37
- 239000002994 raw material Substances 0.000 claims abstract description 37
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims abstract description 31
- 229910052801 chlorine Inorganic materials 0.000 claims abstract description 19
- 229910052731 fluorine Inorganic materials 0.000 claims abstract description 19
- 238000000034 method Methods 0.000 claims abstract description 14
- 238000004519 manufacturing process Methods 0.000 claims abstract description 9
- 239000000203 mixture Substances 0.000 claims abstract description 8
- 238000000465 moulding Methods 0.000 claims description 49
- 239000003575 carbonaceous material Substances 0.000 claims description 5
- 238000010438 heat treatment Methods 0.000 abstract description 2
- JEIPFZHSYJVQDO-UHFFFAOYSA-N ferric oxide Chemical compound O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 abstract 3
- 229960005191 ferric oxide Drugs 0.000 abstract 3
- 235000013980 iron oxide Nutrition 0.000 abstract 3
- 239000003610 charcoal Substances 0.000 abstract 1
- 239000002023 wood Substances 0.000 abstract 1
- 239000000126 substance Substances 0.000 description 29
- 239000000460 chlorine Substances 0.000 description 16
- 239000002245 particle Substances 0.000 description 11
- 239000000843 powder Substances 0.000 description 10
- 238000010586 diagram Methods 0.000 description 7
- 239000000463 material Substances 0.000 description 7
- 239000007789 gas Substances 0.000 description 6
- 239000011435 rock Substances 0.000 description 5
- 230000005484 gravity Effects 0.000 description 4
- 230000007423 decrease Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 2
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 2
- 239000011737 fluorine Substances 0.000 description 2
- 230000005764 inhibitory process Effects 0.000 description 2
- YOBAEOGBNPPUQV-UHFFFAOYSA-N iron;trihydrate Chemical compound O.O.O.[Fe].[Fe] YOBAEOGBNPPUQV-UHFFFAOYSA-N 0.000 description 2
- 238000011946 reduction process Methods 0.000 description 2
- 238000009628 steelmaking Methods 0.000 description 2
- 206010053759 Growth retardation Diseases 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 239000000567 combustion gas Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/78—Recycling of wood or furniture waste
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- Processing Of Solid Wastes (AREA)
- Treatment Of Sludge (AREA)
- Manufacture And Refinement Of Metals (AREA)
- Manufacture Of Iron (AREA)
Abstract
Description
本発明は、製鉄プロセスで発生する製鉄ダストなどの酸化鉄系原料を炭材等と混合して成型し、回転床炉において加熱還元処理を行う還元処理用ダスト成型物およびそれを使用する還元鉄製造方法に関する。 The present invention relates to a dust molding for reduction treatment in which an iron oxide-based raw material such as iron-making dust generated in an iron-making process is mixed with a carbonaceous material and molded, and subjected to a heat reduction treatment in a rotary bed furnace, and reduced iron using the same It relates to a manufacturing method.
近年、製鉄プロセスで発生する製鉄ダストなどの酸化鉄系原料を炭材等と混合して成型し、回転床炉において加熱還元処理を行うことにより、製鉄ダストを鉄原料として利用されており、その処理方法について種々の提案がなされている。
例えば、特開２００３−３２１７号公報には、還元焙焼中のダストに水分を添加することによって、ダストから効率的に塩素および弗素を分離する方法が開示されている。
しかし、この特開２００３−３２１７号公報の方法では水分を添加することにより炉内温度が低下して、還元炉の生産性の悪化および燃料使用量の増加は避けられず、 回転床炉での塩素、弗素を含む鉄鋼ダストの処理方法として有効ではなかった。
For example, Japanese Patent Application Laid-Open No. 2003-3217 discloses a method for efficiently separating chlorine and fluorine from dust by adding moisture to the dust during reduction roasting.
However, in the method of Japanese Patent Application Laid-Open No. 2003-3217, the temperature inside the furnace is lowered by adding water, so that the productivity of the reduction furnace is deteriorated and the amount of fuel used is inevitably increased. It was not effective as a method for treating steel dust containing chlorine and fluorine.
本発明は、前述のような従来技術の問題点を解決し、ＣｌやＦなどの揮発成分を含有する酸化鉄系原料を使用しても効率的・安定的に鉄原料として再資源化できる還元処理用ダスト成型物およびそれを使用する還元鉄製造方法を提供することを課題とする。 The present invention solves the problems of the prior art as described above, and can be efficiently and stably recycled as an iron material even when an iron oxide-based material containing volatile components such as Cl and F is used. It is an object to provide a dust molding for treatment and a method for producing reduced iron using the same.
本発明は、前記課題を解決するために鋭意検討の結果なされたものであり、ＦｅとＣｌやＦなどの揮発成分との比率およびダスト成型時の気孔率を特定範囲にすることによって、ＣｌやＦなどの揮発成分を含有する酸化鉄系原料を使用しても効率的・安定的に鉄原料として再資源化できる還元処理用ダスト成型物およびそれを使用する還元鉄製造方法を提供するものであり、その要旨とするところは特許請求の範囲に記載した通りの下記内容である。
（１）製鉄プロセスで発生する製鉄ダストなどの酸化鉄系原料を炭材等と混合して成型し、回転床炉において加熱還元処理を行う還元処理用ダスト成型物であって、前記酸化鉄系原料の組成が下記（Ａ）式を満足し、かつ、ダスト成型時の気孔率が30%以下であることを特徴とする還元処理用ダスト成型物。
原料中の鉄濃度 (以下、T.Feとも言う)／Cl、F、Zn、Na、K、Pbの合計濃度≧１０・・・（Ａ）
（２）前記酸化鉄系原料の組成が下記（Ｂ）式を満足し、かつ、ダスト成型時の気孔率が30%以下であることを特徴とする（１）に記載の還元処理用ダスト成型物。
原料中の鉄濃度 (T.Fe)／Cl、F、Zn、Na、K、Pbの合計濃度≧２０・・・（Ｂ）
（３）前記ダスト成型時の気孔率が下記（Ｃ）式を満足することを特徴とする（２）に記載の還元処理用ダスト成型物。
１／（原料中の鉄濃度 (T.Fe)／Cl、F、Zn、Na、K、Pbの合計濃度）
+０．０１９×（ダスト成型時の気孔率）＜０．７１・・・（Ｃ）
（４）前記酸化鉄系原料が二種類以上の製鉄ダストを混合した原料であることを特徴とする（１）乃至（３）に記載の還元処理用ダスト成型物
（５）（１）乃至（４）に記載の還元処理用ダスト成型物を使用して、回転床炉にて加熱還元することを特徴とする還元鉄製造方法。
The present invention has been made as a result of intensive studies in order to solve the above problems, and by adjusting the ratio of Fe to volatile components such as Cl and F and the porosity during dust molding within a specific range, Cl and Provided is a dust molding for reduction treatment that can be efficiently and stably recycled as an iron raw material even when an iron oxide-based raw material containing a volatile component such as F is used, and a method for producing reduced iron using the same. The gist thereof is as follows, as described in the claims.
(1) A reduced dust forming product that is formed by mixing an iron oxide-based material such as iron-making dust generated in an iron-making process with a carbonaceous material and performing a heat reduction treatment in a rotary bed furnace, the iron oxide-based A dust molding for reduction treatment, wherein the composition of the raw material satisfies the following formula (A) and the porosity during dust molding is 30% or less.
Iron concentration in raw material (hereinafter also referred to as T.Fe) / Total concentration of Cl, F, Zn, Na, K, Pb ≧ 10 (A)
(2) Dust molding for reduction treatment according to (1), wherein the composition of the iron oxide-based raw material satisfies the following formula (B) and the porosity during dust molding is 30% or less object.
Iron concentration in raw material (T.Fe) / Total concentration of Cl, F, Zn, Na, K, Pb ≧ 20 (B)
(3) The dust molded product for reduction treatment according to (2), wherein the porosity during the dust molding satisfies the following formula (C):
1 / (Concentration of iron in raw material (T.Fe) / Total concentration of Cl, F, Zn, Na, K, Pb)
+ 0.019 × (porosity during dust molding) <0.71 (C)
(4) The reduction molding dust molded product (5) (1) to (1) according to (1) to (3), wherein the iron oxide-based raw material is a raw material in which two or more types of ironmaking dust are mixed. A method for producing reduced iron, characterized in that the reduction molding dust molded product according to 4) is used for heat reduction in a rotary bed furnace.
本発明によれば、ＦｅとＣｌやＦなどの揮発成分との比率およびダスト成型時の気孔率を特定範囲にすることによって、ＣｌやＦなどの揮発成分を含有する酸化鉄系原料を使用しても効率的・安定的に鉄原料として再資源化できる還元処理用ダスト成型物、および、それを使用して回転床炉にて加熱還元する還元鉄製造方法を提供することができ、産業上有用な著しい効果を奏する。 According to the present invention, the iron oxide raw material containing volatile components such as Cl and F is used by setting the ratio of Fe and volatile components such as Cl and F and the porosity during dust molding to a specific range. However, it is possible to provide a reduced dust processing molding that can be efficiently and stably recycled as an iron raw material, and a reduced iron production method that uses it to heat and reduce in a rotary bed furnace. Useful and significant effect.
本発明を実施するための最良の形態について、図１乃至図８を用いて詳細に説明する。
図１は、本発明におけるダスト成型物の還元前の断面写真であり、図２はその還元後の断面写真である。
製鉄プロセスで発生する製鉄ダストなどの酸化鉄系原料を炭材（約１０％）等と混合して成型し、回転床炉において加熱還元処理を行う還元処理用ダスト成型物は、図２の断面写真のように還元過程でダスト原料中の鉄粒子同士がネットワークを組むことにより、強度が向上する。
ここに、製鉄ダストとしては、高炉製銑工程・転炉製鋼工程・電気炉製鋼工程などでの発生ダスト、圧延工程での発生 スケール、メッキ工程で発生するスラッジ類が挙げられる。
一方で、Cl, F, Zn, Na, K, Pb (以下揮発物質) を多量に含むダスト類を原料として用いた場合、加熱、還元過程においてこれらの物質が揮発(酸化物として存在する揮発物質は、回転床炉内で還元されると同時に揮発)するため、還元物の気孔率が高くなり、また鉄粒子同士のネットワークもできにくい。
その結果、還元物の強度が低くなり、回転床炉から排出スクリューにより払い出される過程において崩壊し、歩留まりの低下、操業上の問題(岩盤炉床成長、排ガス吸引ダクト閉塞)を引き起こす要因となる。
The best mode for carrying out the present invention will be described in detail with reference to FIGS.
FIG. 1 is a cross-sectional photograph of the dust molding according to the present invention before the reduction, and FIG. 2 is a cross-sectional photograph after the reduction.
Fig. 2 shows a cross-sectional view of the dust molding for reduction treatment, in which iron oxide-based materials such as iron-making dust generated in the iron-making process are mixed with carbonaceous materials (about 10%) and then heated and reduced in a rotary bed furnace. As shown in the photo, the iron particles in the dust raw material form a network during the reduction process, thereby improving the strength.
Here, examples of the ironmaking dust include dust generated in the blast furnace ironmaking process, converter steelmaking process, electric furnace steelmaking process, etc., the generation scale in the rolling process, and sludge generated in the plating process.
On the other hand, when dusts containing a large amount of Cl, F, Zn, Na, K, Pb (hereinafter referred to as volatile substances) are used as raw materials, these substances are volatilized (volatile substances present as oxides) during the heating and reduction process. Is reduced in the rotating bed furnace and volatilizes at the same time), the porosity of the reduced product becomes high and it is difficult to form a network of iron particles.
As a result, the strength of the reduced product becomes low, and it collapses in the process of being discharged from the rotary bed furnace by the discharge screw, causing a decrease in yield and operational problems (rock bed hearth growth, exhaust gas suction duct blockage).
図３は、鉄濃度(T.Fe)／揮発物質濃度≒１の揮発物質を多量に含むダスト成型物を還元試験した後のサンプルを示す図である。
ここに、
原料中の鉄濃度（T.Fe）：還元前のダスト成型物中の合計Fe濃度（質量％）、
揮発物質濃度：還元前のCl、F、Zn、Na、K、Pbの合計濃度（質量％）を示す。
図３に示すように、揮発物質濃度が高いダスト成型物の還元後試料は非常に多孔質となり、鉄粒子同士のネットワークも弱く、強度は低い。
FIG. 3 is a diagram showing a sample after a reduction test of a dust molding containing a large amount of volatile substances of iron concentration (T.Fe) / volatile substance concentration≈1.
here,
Iron concentration in raw material (T.Fe): Total Fe concentration (% by mass) in the dust molding before reduction
Volatile substance concentration: Total concentration (% by mass) of Cl, F, Zn, Na, K, and Pb before reduction.
As shown in FIG. 3, the sample after reduction of the dust molding with a high concentration of volatile substances is very porous, the network of iron particles is weak, and the strength is low.
一方、図４は、原料中の鉄濃度(T.Fe)／揮発物質濃度≒１０の揮発物質が比較的少ないダスト成型物を還元試験した後のサンプルを示す図である。
図４に示すように、揮発物質が少ないため、還元後試料は緻密であり鉄粒子同士がネットワークを組みやすく、強度は高い。
回転床炉払い出し部での崩壊を抑制するためには、還元物強度を確保する必要がある。還元物強度確保のためには、ダスト原料中の揮発物質の濃度と鉄濃度(T,Fe)のバランス及び造粒物の気孔率が重要となる。
そこで、本発明においては、ダスト成型物を形成する酸化鉄系原料の組成が下記（Ａ）式を満足し、かつ、ダスト成型時の気孔率が30%以下であることを特徴とする。
原料中の鉄濃度 (T.Fe)／Cl、F、Zn、Na、K、Pbの合計濃度≧１０・・・（Ａ）
さらに、下記（Ｂ）式を満足することが好ましい。
原料中の鉄濃度 (T.Fe)／Cl、F、Zn、Na、K、Pbの合計濃度≧２０・・・（Ｂ）
ここに、
原料中の鉄濃度（T.Fe）：還元前のダスト成型物中の合計Fe濃度（質量％）、
揮発物質濃度：還元前のCl、F、Zn、Na、K、Pbの合計濃度（質量％）を示す。
また、ダスト成型時の気孔率とは、
気孔率 （％）= (ダスト真比重-ダスト成型時嵩比重) × 100 / ダスト真比重を示す。
On the other hand, FIG. 4 is a diagram showing a sample after a reduction test of a dust molding having a relatively small amount of volatile substances of iron concentration (T.Fe) / volatile substance concentration≈10 in the raw material.
As shown in FIG. 4, since there are few volatile substances, the sample after reduction | restoration is dense, iron particles are easy to form a network, and intensity | strength is high.
In order to suppress collapse at the rotary bed furnace discharge section, it is necessary to ensure the reduced product strength. In order to ensure the strength of the reduced product, the balance between the concentration of volatile substances and the concentration of iron (T, Fe) in the dust material and the porosity of the granulated product are important.
Therefore, the present invention is characterized in that the composition of the iron oxide-based raw material forming the dust molding satisfies the following formula (A) and the porosity during dust molding is 30% or less.
Iron concentration in raw material (T.Fe) / Total concentration of Cl, F, Zn, Na, K, Pb ≧ 10 (A)
Furthermore, it is preferable to satisfy the following formula (B).
Iron concentration in raw material (T.Fe) / Total concentration of Cl, F, Zn, Na, K, Pb ≧ 20 (B)
here,
Iron concentration in raw material (T.Fe): Total Fe concentration (% by mass) in the dust molding before reduction
Volatile substance concentration: Total concentration (% by mass) of Cl, F, Zn, Na, K, and Pb before reduction.
Also, the porosity during dust molding is
Porosity (%) = (Dust True Specific Gravity-Bulk Specific Gravity at Dust Molding) x 100 / Dust True Specific Gravity.
＜還元後試料強度とT.Fe/揮発物質濃度の関係＞
図５は、T.Fe/揮発物質濃度と還元後試料強度との関係を示す図である。
T.Fe/揮発物質濃度 ＜ 10の場合は、揮発物質を多量に含むため、還元後試料は非常にポーラスとなり、鉄粒子同士もネットワークを組みにくいため、還元後試料強度は30kg以下と低い。
10 ≦ T.Fe/揮発物質濃度 ＜ 20の場合は、揮発物質が少なくなり、鉄粒子同士が比較的ネットワークを組みやすくなるため、還元後試料の圧壊強度は30kg以上で、回転床炉からの払い出し時の崩壊は抑制される。
T.Fe/揮発物質濃度 ≧ 20の場合は、鉄粒子同士がネットワークを十分に組み、揮発成分も少ないため還元後試料は緻密になり、強度は50kg以上と高く、回転床炉からの払い出し時の崩壊も問題ないレベルであり、もっとも好ましい。
<Relationship between sample strength after reduction and T.Fe / volatile substance concentration>
FIG. 5 is a diagram showing the relationship between the T.Fe / volatile substance concentration and the sample strength after reduction.
When T.Fe / volatile substance concentration <10, since a large amount of volatile substances are contained, the sample after reduction becomes very porous, and the iron particles are difficult to form a network, so the sample strength after reduction is as low as 30 kg or less.
When 10 ≤ T.Fe / volatile substance concentration <20, the volatile substances are reduced and the iron particles are relatively easy to form a network, so the crushing strength of the sample after reduction is 30 kg or more, Collapse at the time of payout is suppressed.
When T.Fe / volatile substance concentration is ≧ 20, the iron particles are sufficiently networked together, and there are few volatile components, so the sample after reduction becomes dense and the strength is as high as 50 kg or more. The collapse of is at a level where there is no problem, and is most preferable.
＜還元後試料強度とダスト成型時気孔率の関係＞
図６は、ダスト成型時気孔率と還元物の圧壊強度の関係を示す図である。
図６において、○印は鉄濃度(T.Fe)／揮発成分濃度＞２０の場合、△印は鉄濃度(T.Fe)／揮発成分濃度≒１０の場合、□印は鉄濃度(T.Fe)／揮発成分濃度≒１の場合をそれぞれ示している。
ここに、ダスト成型時気孔率とは、
気孔率 （％）= (ダスト真比重-ダスト成型時嵩比重) × 100 / ダスト真比重を示す。
ダスト成型物の還元後強度は鉄粒子同士がネットワークを組むことにより向上する。従って還元物の気孔率が高い場合、ネットワークが形成されにくくなり強度は低下する。還元後の気孔率については、ダスト中の揮発成分濃度だけでなく、ダスト成型時の気孔率にも大きく影響を受ける。
仮に上記条件を十分に満足した場合でも、成型時の気孔率が高すぎる場合、還元物は鉄粒子同士のネットワークが十分に形成されず、強度は低下する。
図６に示すように、原料中の鉄濃度 (T.Fe)／Cl、F、Zn、Na、K、Pbの合計濃度≧１０を満足している場合でも、ダスト成型時の気孔率が30%を超えるレベルになると、還元物の強度は著しく低下することがわかる。
ただし、本発明者らは、気孔率が30％を超えるレベルでも、ある条件を満足すれば還元後試料の圧壊強度は30kg以上で、回転床炉からの払い出し時の崩壊は抑制されることを見出した。
図９に示す様に、還元後試料強度とT.Fe/揮発成分濃度、タ゛スト成型時気孔率を用いた指標
強度ハ゜ラメーター(指標) = 1/(タ゛スト中鉄分濃度/揮発成分濃度) + 0.019×気孔率
(ただし、30<気孔率の範囲)
と圧壊強度の間に以下のような良好な相関関係があることを見いだした。
上記式右辺の第１項は、成分の圧壊強度に対する寄与の項であり、第２項は組織構造の圧壊強度に対する寄与の項であり、気孔率に対し実験的に求めた寄与度（係数）を０．０１９としている。
つまり、図９より、還元後試料強度>30kgを確保するためには
強度ハ゜ラメータ(指標) < 0.71
を満足することが必要である。
<Relationship between sample strength after reduction and porosity during dust molding>
FIG. 6 is a diagram showing the relationship between the porosity during dust molding and the crushing strength of the reduced product.
In FIG. 6, ◯ indicates iron concentration (T.Fe) / volatile component concentration> 20, △ indicates iron concentration (T.Fe) / volatile component concentration≈10, and □ indicates iron concentration (T.Fe. Fe) / volatile component concentration≈1 respectively.
Here, the porosity during dust molding is
Porosity (%) = (Dust True Specific Gravity-Bulk Specific Gravity at Dust Molding) x 100 / Dust True Specific Gravity.
The strength after reduction of the dust molding is improved by forming a network of iron particles. Therefore, when the porosity of the reduced product is high, a network is hardly formed and the strength is lowered. The porosity after reduction is greatly influenced not only by the concentration of volatile components in the dust but also by the porosity during dust molding.
Even if the above conditions are sufficiently satisfied, if the porosity at the time of molding is too high, the reduced product does not sufficiently form a network of iron particles, and the strength decreases.
As shown in FIG. 6, even when the total concentration of iron concentration in the raw material (T.Fe) / Cl, F, Zn, Na, K, and Pb ≧ 10 is satisfied, the porosity during dust molding is 30 It can be seen that when the level exceeds%, the strength of the reduced product is significantly reduced.
However, the present inventors have found that even if the porosity exceeds 30%, if a certain condition is satisfied, the crushing strength of the sample after reduction is 30 kg or more, and the collapse at the time of withdrawal from the rotary bed furnace is suppressed. I found it.
As shown in Fig. 9, the sample strength after reduction, T.Fe / volatile component concentration, index strength parameter (index) using the dust molding porosity (index) = 1 / (iron concentration in the dust / volatile component concentration) + 0.019 × Porosity
(However, 30 <porosity range)
The following good correlations were found between crushing strength and crushing strength.
The first term on the right side of the above formula is the term of contribution to the crushing strength of the component, the second term is the term of contribution to the crushing strength of the tissue structure, and the contribution (coefficient) obtained experimentally for the porosity. Is set to 0.019.
In other words, from FIG. 9, in order to secure the sample strength after reduction> 30 kg, the strength parameter (index) <0.71
It is necessary to satisfy
図７および図８は、本発明におけるダスト成型物の還元後の強度確保による効果を示す図である。
＜ 岩盤炉床成長抑制効果＞
図７は、ダスト処理量に対する岩盤炉床成長量（ｍｍ/ｔ-ダスト）を示す図である。
回転床炉によりダスト類を用いて還元鉄を製造する方法において、ダスト還元鉄は、排出スクリューにより回転炉床より払い出される。この過程において、ダスト還元鉄が崩壊し粉が発生、粉と炉床材と反応し、融着物が成長していく「岩盤炉床」と呼ばれる現象が起こり、この現象が継続すると、炉床レベルが上昇するため、操業上問題となる。
図７の右側のグラフに示すように、T.Fe/揮発物質濃度 ＜ 10の場合は、還元物の強度が低く排出過程で多量の粉が発生するため、岩盤炉床成長を助長することになる。
これに対して、図７の左側のグラフに示すように、T.Fe/揮発物質濃度 ＞20の場合は、還元物の強度が確保されるため岩盤炉床成長が抑制される。
FIG. 7 and FIG. 8 are diagrams showing the effect of ensuring the strength after reduction of the dust molding in the present invention.
<Rock bed hearth growth suppression effect>
FIG. 7 is a diagram showing the rock hearth growth amount (mm / t-dust) with respect to the dust processing amount.
In the method for producing reduced iron using dust in a rotary bed furnace, the dust reduced iron is discharged from the rotary hearth by a discharge screw. During this process, dust-reduced iron breaks down, generates powder, reacts with the powder and hearth material, and a phenomenon called a “rock bed hearth” occurs in which the fused material grows. Will raise operational problems.
As shown in the graph on the right side of FIG. 7, when T.Fe / volatile substance concentration <10, the strength of the reduced product is low and a large amount of powder is generated during the discharge process. Become.
On the other hand, as shown in the graph on the left side of FIG. 7, when T.Fe / volatile substance concentration> 20, the strength of the reduced product is ensured, and the rock hearth growth is suppressed.
＜ダスト還元物の歩留まり低減抑制効果＞
図８は、粒径が１ｍｍ未満（-１ｍｍ）の粉率（％）を比較する図である。
回転床炉内で発生する排ガス(バーナー燃焼ガス、ダスト還元時発生ガス等)については、炉入り口付近に設けられた排ガス吸引ダクトより排出される。
この回転床炉からダスト還元鉄排出時に排出スクリューにより壊されて発生した粉(特に微粉)の一部は、巻上げられて排ガス吸引ダクトに吸引され、歩留まり低下の要因となる。
図８の右側のグラフに示すように、T.Fe/揮発物質濃度 ＜ 10の場合は、還元鉄の強度が低く排出時に多量に粉が発生するため、歩留まり低下が大きくなる。
これに対して、図８の左側のグラフに示すように、T.Fe/揮発物質濃度 ＞20の場合は、還元物の強度が確保されるため、排出時の粉発生を抑え、歩留まり低下を抑制することができる。
<Inhibition of yield reduction of reduced dust products>
FIG. 8 is a diagram comparing the powder ratio (%) when the particle size is less than 1 mm (−1 mm).
Exhaust gas (burner combustion gas, gas generated during dust reduction, etc.) generated in the rotary bed furnace is exhausted from an exhaust gas suction duct provided near the furnace entrance.
Part of the powder (particularly fine powder) generated by being broken by the discharge screw when dust-reduced iron is discharged from the rotary bed furnace is wound up and sucked into the exhaust gas suction duct, which causes a reduction in yield.
As shown in the graph on the right side of FIG. 8, when T.Fe / volatile substance concentration <10, the strength of reduced iron is low and a large amount of powder is generated at the time of discharge, resulting in a large decrease in yield.
On the other hand, as shown in the graph on the left side of FIG. 8, when T.Fe / volatile substance concentration> 20, the strength of the reduced product is secured, so that the generation of powder during discharge is suppressed and the yield is reduced. Can be suppressed.
＜排出系ダクト内壁への飛散ダスト付着抑制効果＞
排ガス吸引ダクトに吸引された飛散ダストは、その一部が酸化鉄系ダストとその他の酸化物系ダストとの間で低融点化合物を形成、ダクト通過過程で温度が下がり、ダクト内壁に付着する。ダクト内壁へのダスト付着量は飛ダスト量に依存する。
従って、図８の左側のグラフに示すように、T.Fe/揮発物質濃度 ＞20の場合は、還元物の強度を確保し、排出時の排出スクリューによる粉発生を低減することにより、ダクト内壁へのダスト付着を抑制することができる。
<Inhibition effect of scattered dust on the inner wall of the exhaust duct>
Part of the scattered dust sucked into the exhaust gas suction duct forms a low-melting-point compound between iron oxide dust and other oxide dust, and the temperature drops during the passage through the duct and adheres to the inner wall of the duct. The amount of dust attached to the inner wall of the duct depends on the amount of flying dust.
Therefore, as shown in the graph on the left side of FIG. 8, when T.Fe / volatile substance concentration> 20, the strength of the reduced product is ensured and the generation of powder by the discharge screw during discharge is reduced, thereby reducing the duct inner wall. It is possible to suppress dust adhesion to the surface.
Claims (5)
前記酸化鉄系原料の組成が下記（Ａ）式を満足し、かつ、ダスト成型時の気孔率が30%以下であることを特徴とする還元処理用ダスト成型物。
原料中の鉄濃度 (T.Fe)／Cl、F、Zn、Na、K、Pbの合計濃度≧１０・・・（Ａ） It is a dust molding for reduction treatment in which iron oxide-based raw materials such as iron-making dust generated in the iron making process are mixed with carbonaceous material and molded, and heat reduction treatment is performed in a rotary bed furnace,
A reduction molding dust molded product characterized in that the composition of the iron oxide-based raw material satisfies the following formula (A) and the porosity during dust molding is 30% or less.
Iron concentration in raw material (T.Fe) / Total concentration of Cl, F, Zn, Na, K, Pb ≧ 10 (A)
原料中の鉄濃度 (T.Fe)／Cl、F、Zn、Na、K、Pbの合計濃度≧２０・・・（Ｂ） 2. The dust molded product for reduction treatment according to claim 1, wherein the composition of the iron oxide-based raw material satisfies the following formula (B) and the porosity at the time of dust molding is 30% or less.
Iron concentration in raw material (T.Fe) / Total concentration of Cl, F, Zn, Na, K, Pb ≧ 20 (B)
１／（原料中の鉄濃度 (T.Fe)／Cl、F、Zn、Na、K、Pbの合計濃度）
+０．０１９×（ダスト成型時の気孔率）＜０．７１・・・（Ｃ） The dust molded product for reduction treatment according to claim 2, wherein the porosity during the dust molding satisfies the following formula (C).
1 / (Concentration of iron in raw material (T.Fe) / Total concentration of Cl, F, Zn, Na, K, Pb)
+ 0.019 × (porosity during dust molding) <0.71 (C)
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| JP2010248622A (en) * | 2009-03-27 | 2010-11-04 | Nippon Steel Corp | Method for producing reduced iron |
| KR101460198B1 (en) | 2012-11-07 | 2014-11-10 | 주식회사 포스코 | Manufacturing method of reduced iron |
| WO2015005187A1 (en) * | 2013-07-08 | 2015-01-15 | 株式会社神戸製鋼所 | Method for producing reduced iron |
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| JP2002194410A (en) * | 2000-10-18 | 2002-07-10 | Nippon Steel Corp | Method for operating rotary furnace hearth type reducing furnace, method for producing pig iron and granular iron oxide-reduced material |
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| JP2003089813A (en) * | 2001-09-14 | 2003-03-28 | Nippon Steel Corp | Method for reduction of iron oxide |
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| JP2002194410A (en) * | 2000-10-18 | 2002-07-10 | Nippon Steel Corp | Method for operating rotary furnace hearth type reducing furnace, method for producing pig iron and granular iron oxide-reduced material |
| JP2003003217A (en) * | 2001-06-21 | 2003-01-08 | Sumitomo Metal Mining Co Ltd | Method for treating steel dust containing chlorine and fluorine |
| JP2003089813A (en) * | 2001-09-14 | 2003-03-28 | Nippon Steel Corp | Method for reduction of iron oxide |
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| JP2010248622A (en) * | 2009-03-27 | 2010-11-04 | Nippon Steel Corp | Method for producing reduced iron |
| KR101460198B1 (en) | 2012-11-07 | 2014-11-10 | 주식회사 포스코 | Manufacturing method of reduced iron |
| WO2015005187A1 (en) * | 2013-07-08 | 2015-01-15 | 株式会社神戸製鋼所 | Method for producing reduced iron |
| JP2015014042A (en) * | 2013-07-08 | 2015-01-22 | 株式会社神戸製鋼所 | Method of producing reduced iron |
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