JP7533375B2 - Manufacturing method of non-calcined pellets for reduction - Google Patents
Manufacturing method of non-calcined pellets for reduction Download PDFInfo
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- 239000008188 pellet Substances 0.000 title claims description 77
- 238000004519 manufacturing process Methods 0.000 title claims description 13
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 108
- 229910052742 iron Inorganic materials 0.000 claims description 42
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 34
- 239000002994 raw material Substances 0.000 claims description 30
- 239000002893 slag Substances 0.000 claims description 24
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 20
- 239000007787 solid Substances 0.000 claims description 19
- 229910052681 coesite Inorganic materials 0.000 claims description 17
- 229910052906 cristobalite Inorganic materials 0.000 claims description 17
- 239000000377 silicon dioxide Substances 0.000 claims description 17
- 235000012239 silicon dioxide Nutrition 0.000 claims description 17
- 229910052682 stishovite Inorganic materials 0.000 claims description 17
- 229910052905 tridymite Inorganic materials 0.000 claims description 17
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 14
- 229910052593 corundum Inorganic materials 0.000 claims description 14
- 229910001845 yogo sapphire Inorganic materials 0.000 claims description 14
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 12
- 239000002245 particle Substances 0.000 claims description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 6
- 238000002425 crystallisation Methods 0.000 claims description 2
- 230000008025 crystallization Effects 0.000 claims description 2
- 239000000203 mixture Substances 0.000 description 10
- 238000000034 method Methods 0.000 description 9
- 238000005516 engineering process Methods 0.000 description 6
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 5
- 238000000576 coating method Methods 0.000 description 5
- 230000004927 fusion Effects 0.000 description 5
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 4
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 4
- 239000011248 coating agent Substances 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 238000005469 granulation Methods 0.000 description 3
- 230000003179 granulation Effects 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- MBMLMWLHJBBADN-UHFFFAOYSA-N Ferrous sulfide Chemical compound [Fe]=S MBMLMWLHJBBADN-UHFFFAOYSA-N 0.000 description 2
- 239000000440 bentonite Substances 0.000 description 2
- 229910000278 bentonite Inorganic materials 0.000 description 2
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 239000000292 calcium oxide Substances 0.000 description 2
- 235000012255 calcium oxide Nutrition 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 239000000428 dust Substances 0.000 description 2
- 238000000921 elemental analysis Methods 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 229910052500 inorganic mineral Inorganic materials 0.000 description 2
- -1 iron ore Chemical class 0.000 description 2
- 235000013980 iron oxide Nutrition 0.000 description 2
- 239000011707 mineral Substances 0.000 description 2
- 235000010755 mineral Nutrition 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 239000012299 nitrogen atmosphere Substances 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 238000011946 reduction process Methods 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- 238000009628 steelmaking Methods 0.000 description 2
- 235000019738 Limestone Nutrition 0.000 description 1
- 229910019440 Mg(OH) Inorganic materials 0.000 description 1
- WNQQFQRHFNVNSP-UHFFFAOYSA-N [Ca].[Fe] Chemical compound [Ca].[Fe] WNQQFQRHFNVNSP-UHFFFAOYSA-N 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- WETINTNJFLGREW-UHFFFAOYSA-N calcium;iron;tetrahydrate Chemical compound O.O.O.O.[Ca].[Fe].[Fe] WETINTNJFLGREW-UHFFFAOYSA-N 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000010459 dolomite Substances 0.000 description 1
- 229910000514 dolomite Inorganic materials 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 229910052595 hematite Inorganic materials 0.000 description 1
- 239000011019 hematite Substances 0.000 description 1
- 150000002506 iron compounds Chemical class 0.000 description 1
- VBMVTYDPPZVILR-UHFFFAOYSA-N iron(2+);oxygen(2-) Chemical class [O-2].[Fe+2] VBMVTYDPPZVILR-UHFFFAOYSA-N 0.000 description 1
- LIKBJVNGSGBSGK-UHFFFAOYSA-N iron(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Fe+3].[Fe+3] LIKBJVNGSGBSGK-UHFFFAOYSA-N 0.000 description 1
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 1
- 239000006028 limestone Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000002203 pretreatment Methods 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 239000004449 solid propellant Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
- 238000010792 warming Methods 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
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- Manufacture And Refinement Of Metals (AREA)
Description
本発明は、固体還元炉に用いて有効な還元用非焼成ペレットの製造方法に関する。 The present invention relates to a method for producing uncalcined pellets for reduction which are effective for use in a solid reduction furnace.
近年、CO2の増加による地球温暖化を避けるためにその排出量を削減するための各種の技術開発が行なわれている。例えば、製鉄業の分野において、シャフト炉に代表される固体還元炉では多くの場合に非焼成ペレットが使用されている。その理由は、通常の焼成ペレットの操業では焼成の過程で不可避にCO2の発生が生じる。しかし、このことはCO2削減の観点からは望ましいことではなく、非焼成ペレットの使用が注目されている。 In recent years, various technologies have been developed to reduce CO2 emissions in order to prevent global warming caused by an increase in CO2 . For example, in the field of steelmaking, non-calcined pellets are often used in solid reduction furnaces, such as shaft furnaces. The reason for this is that in normal operations using calcined pellets, CO2 is inevitably generated during the calcination process. However, this is not desirable from the perspective of reducing CO2 , and the use of non-calcined pellets has attracted attention.
とくに、水素ベースの還元プロセスである固体還元炉による製鉄方法の分野では、この方法に用いられる非焼成ペレットについての研究が進められている。ところで、前記固体還元炉では、装入原料(非焼成ペレット)が炉内の高温領域を通過する際に、該ペレット中のヘマタイト相が還元されてマグネタイト相に変化するときに体積膨張を伴い、粉化現象を起こす他、金属鉄どうしの接触・融着の他、低融点スラグどうしの接触、融着を招くことが知られている。その結果として、炉内ではクラスタリングが生じたり、炉内のペレットが動かなくなって炉底部から取り出せなくなる棚吊現象を招くことが知られている。とくに、水素ベースでの還元を行う固体還元炉においては、このクラスタリングは解決すべき非常に大きな課題である。 In particular, in the field of ironmaking methods using solid reduction furnaces, which are hydrogen-based reduction processes, research is being conducted on the non-sintered pellets used in this method. However, in the solid reduction furnace, when the charged raw materials (non-sintered pellets) pass through the high-temperature region in the furnace, the hematite phase in the pellets is reduced and changes to magnetite phase, which is accompanied by volume expansion, and is known to cause pulverization, contact and fusion between metallic iron, and contact and fusion between low-melting-point slag. As a result, it is known that clustering occurs in the furnace, and the pellets in the furnace become stuck and cannot be removed from the bottom of the furnace, resulting in a hanging phenomenon. In particular, in solid reduction furnaces that perform hydrogen-based reduction, this clustering is a very big issue that must be resolved.
このような背景の下、従来、前述した固体還元炉内で観察されるクラスタリングの防止を目的とした幾つかの先行技術が提案されている。例えば、特許文献1では、Ca(OH)2やMg(OH)2をペレット表面に被覆する方法を提案しており、特許文献2では、焼成塊成鉱(ペレット)の表面を粉粒状個体燃料で被覆することで還元粉化を防止すること並びにふくれの少ない焼成ペレットを得る方法を提案し、そして、特許文献3では焼成ペレットの表面をセメント配合鉄鉱石で被覆することで固体還元炉内でのクラスタリングの発生を防止すると共に熱ロスの低減ならびに操業効率の向上を図ることとしており、さらに、特許文献4ではCaxFeyOz(1<y/x≦2;1≦z)からなるカルシウム鉄化合物を含有する物質を被覆する技術を提案している。 Under such a background, several prior arts have been proposed for the purpose of preventing the clustering observed in the above-mentioned solid reduction furnace. For example, Patent Document 1 proposes a method of coating the pellet surface with Ca(OH) 2 or Mg(OH) 2 , Patent Document 2 proposes a method of coating the surface of the fired agglomerate (pellet) with pulverized solid fuel to prevent reduction disintegration and obtain fired pellets with less swelling, and Patent Document 3 proposes coating the surface of the fired pellet with cement-blended iron ore to prevent the occurrence of clustering in the solid reduction furnace, reduce heat loss, and improve operation efficiency, and Patent Document 4 proposes a technology of coating with a substance containing a calcium iron compound consisting of CaxFeyOz (1<y/x≦2; 1≦z).
前記各従来技術(特許文献1-4)は、そのいずれもがシャフト炉等の固体還元炉内の高温域(500~600℃)付近で観察されるクラスタリングの原因となる還元後の金属鉄どうしの接触を、主として非金属成分を介在させることで低減させる方法である。しかし、発明者らの研究によると、前述した従来技術のクラスタリング防止方法は不十分であることに加え、例えば非金属成分の被覆工程を別に採用する必要がありコスト高になる他、専用の設備の追加が必要となるなどの課題があった。 All of the above-mentioned conventional technologies (Patent Documents 1-4) are methods for reducing contact between metallic iron particles after reduction, which is the cause of clustering observed near the high temperature range (500-600°C) in a solid reduction furnace such as a shaft furnace, mainly by using non-metallic components. However, according to the inventors' research, the above-mentioned conventional methods for preventing clustering are insufficient, and they have problems such as the need to adopt a separate coating process for non-metallic components, which increases costs, and requires the addition of dedicated equipment.
そこで、本発明の目的は、固体還元炉で用いる非焼成ペレットの製造に当たり、所定量の高粘性のスラグ成分を含有させることで、低融点スラグどうしの接触機会を減らして、融着を阻止することでクラスタリングの防止に有効な非焼成ペレットとその製造方法を提案することにある。 The object of the present invention is to propose a method for producing non-sintered pellets for use in solid reduction furnaces that contains a predetermined amount of highly viscous slag components, thereby reducing the chance of contact between low-melting-point slags and preventing fusion, thereby effectively preventing clustering.
本発明は、従来技術が抱えている前述した課題を解決できると共に、前記目的を実現するために開発した技術であって、トータルFe(T.Fe)に対する高粘性のスラグ成分(Al2O3+MgO+SiO2)の割合が下記(1)式を満たすようにしてなる還元用非焼成ペレットの製造に当たり、鉄含有原料として、平均LOI(強熱減量)が5%以上となるように配合したものを用いると共に、予め平均LOI(強熱減量)が2%以下となるように脱結晶水のための事前処理を施したものを用いることを特徴とする還元用非焼成ペレットの製造方法を提案する。
記
(Al2O3+MgO+SiO2)/T.Fe≧0.12 ・・・(1)
ただし、Al2O3: 非焼成ペレット中のAl2O3の成分濃度(質量%)
MgO: 非焼成ペレット中のMgOの成分濃度(質量%)
SiO2: 非焼成ペレット中のSiO2の成分濃度(質量%)
T.Fe: 非焼成ペレット中のT.Feの成分濃度(質量%)
The present invention is a technology developed to solve the above-mentioned problems of the conventional technology and to achieve the above-mentioned object, and proposes a method for producing non-sintered pellets for reduction in which the ratio of high viscous slag components ( Al2O3 + MgO + SiO2 ) to total Fe (T.Fe) satisfies the following formula (1): the iron-containing raw material is blended so that the average LOI (loss on ignition) is 5% or more, and is pre-treated to remove water of crystallization so that the average LOI (loss on ignition) is 2% or less .
(Al 2 O 3 +MgO+SiO 2 )/T. Fe≧0.12 (1)
Where, Al 2 O 3 : component concentration of Al 2 O 3 in the non-sintered pellet (mass %)
MgO: MgO component concentration (mass%) in unsintered pellets
SiO2 : SiO2 component concentration in the unsintered pellet (mass%)
T.Fe: Component concentration (mass%) of T.Fe in unsintered pellets
なお、本発明において前記還元用非焼成ペレットの製造に当っては、
(a)トータルFe(T.Fe)に対する高粘性のスラグ成分(Al2O3+MgO+SiO2)の割合が下記(2)式を満たすようにしたものであること、
記
(Al2O3+MgO+SiO2)/T.Fe≧0.15 ・・・(2)
ただし、Al2O3: 非焼成ペレット中のAl2O3の成分濃度(質量%)
MgO: 非焼成ペレット中のMgOの成分濃度(質量%)
SiO2: 非焼成ペレット中のSiO2の成分濃度(質量%)
T.Fe: 非焼成ペレット中のT.Feの成分濃度(質量%)
(b)前記鉄含有原料は、M.Feを4質量%以上24質量%以下含有すること、
(c)前記鉄含有原料は、固体還元炉で還元された粒径3mm以下の還元鉄であること、
(d)前記還元鉄はM.Feを79質量%以上含むこと、
がより好ましい実施形態を提供できるものと考えられる。
In the present invention, in producing the non-sintered pellets for reduction,
(a) The ratio of the highly viscous slag components (Al 2 O 3 +MgO+SiO 2 ) to the total Fe (T.Fe) satisfies the following formula (2):
(Al 2 O 3 +MgO+SiO 2 )/T. Fe≧0.15 (2)
Where, Al 2 O 3 : component concentration of Al 2 O 3 in the non-sintered pellet (mass %)
MgO: MgO component concentration (mass%) in unsintered pellets
SiO2 : SiO2 component concentration in the unsintered pellet (mass%)
T.Fe: Component concentration of T.Fe in unsintered pellets (mass% )
(b ) the iron-containing raw material contains M.Fe in an amount of 4% by mass or more and 24% by mass or less;
( c ) the iron-containing raw material is reduced iron having a particle size of 3 mm or less that has been reduced in a solid reduction furnace;
( d ) the reduced iron contains 79 mass% or more of M.Fe;
It is believed that this provides a more preferred embodiment.
前述した構成に係る本発明に係る還元用非焼成ペレットの製造方法によれば、焼成過程でのCO2の発生がなくCO2削減の観点から望ましく、とくにトータル鉄に対して高粘性のスラグ成分(Al2O3、MgO、SiO2)を相対的に多く含有させることで、固体還元炉内での還元中におけるFeOによる低融点のスラグの発生とその流動性を低下させることができる。その結果、こうしたスラグが介在することによるペレットどうしの接触、融着の機会を防止することができるようになり、ひいては課題である還元炉内での前述したクラスタリングを効果的に防止することができる。 According to the manufacturing method of non-sintered pellets for reduction according to the present invention having the above-mentioned configuration, no CO2 is generated during the sintering process, which is desirable from the viewpoint of reducing CO2 , and in particular, by making the slag components (Al2O3 , MgO, SiO2 ) with high viscosity relatively large relative to the total iron, it is possible to reduce the generation of low-melting-point slag due to FeO and its fluidity during reduction in a solid reduction furnace. As a result, it is possible to prevent contact and fusion between pellets due to the presence of such slag, and thus it is possible to effectively prevent the aforementioned problematic clustering in the reduction furnace.
また、本発明に係る製造方法によれば、鉄含有原料として高LOI原料を配合使用することで得られる非焼成ペレットの多孔質化をもたらすことで、金属鉄どうしの接触機会の低減を図ることができるようになるので、クラスタリングの効果的な防止を実現して、固体還元炉操業の効率向上を図ることができる。 In addition, according to the manufacturing method of the present invention, by using a high LOI raw material as the iron-containing raw material, the non-sintered pellets obtained are made porous, which reduces the chances of contact between metallic iron particles, thereby effectively preventing clustering and improving the efficiency of solid reduction furnace operation.
本発明において用いる固体還元炉としては、水素ガスなどを還元ガスとして用い、還元用非焼成ペレットをその炉内に装入し、これを還元率にして90%以上のFeにまで還元するための炉である。この固体還元炉の操業においては、炉内に装入する原料、すなわち非焼成ペレットの性状の如何が重要である。 The solid reduction furnace used in the present invention is a furnace that uses hydrogen gas or the like as a reducing gas, loads non-sintered pellets for reduction into the furnace, and reduces them to a reduction rate of 90% or more of Fe. In operating this solid reduction furnace, the properties of the raw material loaded into the furnace, i.e., the non-sintered pellets, are important.
その非焼成ペレットとしては、前述した固体還元炉内の高温領域(500~800℃)におけるペレットどうしの接触、互いの融着によるクラスタリングの防止を図ることができるかどうかが何よりも重要である。こうした要請に対し、本発明では、金属鉄すなわち鉄鉱石のような鉄酸化物や硫化鉄、製鉄ダストのような鉄含有原料と、高粘性のスラグ成分すなわち粘性成分との関係について検討した。その結果、諸原料の炉内での流動性の観点から、とりわけ高粘性のスラグ成分との関係を適性に管理することが好ましいことが判明した。即ち、炉内では、常に高粘性のスラグが生じるようにすることで、高温域での好ましくない流動を抑え、このことにより、スラグどうしの融着を防止して、クラスタリングの阻止を図ることができるのである。 For the non-sintered pellets, it is most important to be able to prevent clustering caused by contact and adhesion between pellets in the high temperature range (500-800°C) in the solid reduction furnace mentioned above. In response to this demand, the present invention examines the relationship between iron-containing raw materials such as metallic iron, i.e., iron oxides such as iron ore, iron sulfide, and iron-making dust, and highly viscous slag components, i.e., viscous components. As a result, it was found that, from the viewpoint of the fluidity of the various raw materials in the furnace, it is preferable to properly manage the relationship, especially with highly viscous slag components. In other words, by always producing highly viscous slag in the furnace, undesirable flow in the high temperature range can be suppressed, which prevents the slag from fusing together and inhibits clustering.
前述したように、本発明では、鉄含有原料について或いは鉄鉱石や配合する副原料に対し、高粘性のスラグ成分が一定の割合で含まれるようにしたものにすることが有効であることが分かった。 As mentioned above, in the present invention, it has been found to be effective to make the iron-containing raw material, or the iron ore and auxiliary raw materials to be mixed contain a certain proportion of highly viscous slag components.
その高粘性のスラグとなりうる成分として、とくに(Al2O3、MgO、SiO2)に着目し、その合計量がトータル鉄(T.Fe)に対し、所定の割合を維持するとき、炉内で生成する前記スラグどうしの融着を有効に防止できるようになるのである。 As components that can become the highly viscous slag, attention is paid to (Al 2 O 3 , MgO, SiO 2 ), and when the total amount of these components is maintained at a predetermined ratio to the total iron (T.Fe), it becomes possible to effectively prevent the slag generated in the furnace from fusing together.
それは、還元用非焼成ペレットとしての成分組成が、鉄含有原料中のトータル鉄(T.Fe)に対して、前記高粘性のスラグ成分(Al2O3+MgO+SiO2)を一定の割合で含有させること、即ち、下記(1)式を満たす関係にある非焼成ペレットとすることである。
記
(Al2O3+MgO+SiO2)/T.Fe≧0.12 ・・・(1)
The composition of the non-sintered pellets for reduction is such that the high viscosity slag component (Al 2 O 3 +MgO+SiO 2 ) is contained in a certain ratio relative to the total iron (T.Fe) in the iron-containing raw material, that is, the non-sintered pellets satisfy the following formula (1).
( Al2O3 + MgO+ SiO2 )/T. Fe≧0.12 (1)
上記(1)式において、Al2O3は前記還元用非焼成ペレットのAl2O3の成分濃度(質量%)であり、MgOは前記還元用非焼成ペレットのMgOの成分濃度(質量%)であり、SiO2は前記還元用非焼成ペレットのMgOの成分濃度(質量%)であり、T.Feは前記還元用非焼成ペレットのトータルFe濃度(質量%)である。 In the above formula ( 1 ), Al2O3 is the component concentration (mass%) of Al2O3 in the non-sintered pellets for reduction, MgO is the component concentration (mass%) of MgO in the non-sintered pellets for reduction, SiO2 is the component concentration (mass%) of MgO in the non-sintered pellets for reduction, and T.Fe is the total Fe concentration (mass%) in the non-sintered pellets for reduction.
本発明において、炉内高温域におけるスラグどうしの接触、融着を防ぐという観点からは、前述した高粘性のスラグ成分(Al2O3+MgO+SiO2)とトータル鉄(T.Fe)とのより好ましい関係は、高粘性のスラグ成分量がより多く含まれることとなる下記(2)式に示すとおりである。
記
(Al2O3+MgO+SiO2)/T.Fe≧0.15 ・・・(2)
In the present invention, from the viewpoint of preventing contact and fusion between slags in the high temperature region in the furnace, a more preferable relationship between the above-mentioned high viscosity slag components (Al 2 O 3 +MgO+SiO 2 ) and total iron (T.Fe) is as shown in the following formula (2), in which the amount of the high viscosity slag components is larger.
(Al 2 O 3 +MgO+SiO 2 )/T. Fe≧0.15 (2)
上記(2)式において、Al2O3は前記還元用非焼成ペレットのAl2O3の成分濃度(質量%)であり、MgOは前記還元用非焼成ペレットのMgOの成分濃度(質量%)であり、SiO2は前記還元用非焼成ペレットのMgOの成分濃度(質量%)であり、T.Feは前記還元用非焼成ペレットのトータルFe濃度(質量%)である。 In the above formula (2), Al2O3 is the component concentration (mass%) of Al2O3 in the non-sintered pellets for reduction, MgO is the component concentration (mass%) of MgO in the non-sintered pellets for reduction, SiO2 is the component concentration (mass%) of MgO in the non-sintered pellets for reduction, and T.Fe is the total Fe concentration (mass%) in the non-sintered pellets for reduction.
なお、本発明において、鉄含有原料中のトータルFeとは、金属鉄の他、鉄化合物(酸化鉄、硫化鉄、カルシウムフェライト等)からなる鉄分濃度の合計値であり、一方、高粘性のスラグ成分とは鉄鉱石や製鉄ダスト等の含鉄原料の他、副原料(石灰石、生石灰、ドロマイト等)、バインダー(ベントナイト等)に含まれるAl2O3濃度、MgO濃度、SiO2濃度の合計値である。 In the present invention, the total Fe in the iron-containing raw materials refers to the total concentration of iron consisting of metallic iron and iron compounds (iron oxide, iron sulfide, calcium ferrite, etc.), while the highly viscous slag components refers to the total concentration of Al2O3 , MgO , and SiO2 contained in iron-containing raw materials such as iron ore and steelmaking dust, auxiliary raw materials (limestone, quicklime, dolomite, etc.), and binders (bentonite, etc.).
前記Al2O3濃度、MgO濃度、SiO2濃度は、蛍光X線などの元素分析によりAl濃度、Mg濃度、Si濃度を測定し、それぞれに分子量/原子量を掛けて求めることが出来る。具体的には、たとえば、Al2O3濃度は、蛍光X線などの元素分析により測定されたAl濃度に、Al2O3分子量/Al原子量=101.96/26.98=3.779を掛けて求めることができる。 The Al2O3 concentration, MgO concentration, and SiO2 concentration can be obtained by measuring the Al concentration, Mg concentration, and Si concentration by elemental analysis such as fluorescent X-rays, and multiplying each by the molecular weight/atomic weight. Specifically, for example, the Al2O3 concentration can be obtained by multiplying the Al concentration measured by elemental analysis such as fluorescent X - rays by Al2O3 molecular weight/Al atomic weight = 101.96/26.98 = 3.779.
本発明に係る還元用非焼成ペレットの製造に当たっては、得られる非焼成ペレットについての高粘性のスラグ成分(Al2O3+MgO+SiO2)とトータル鉄(T.Fe)との上述した関係を実現するために、例えば、もともと上述したような関係の成分組成を有する鉄鉱石の1種または複数種の鉄鉱石を配合して使用することで、前述した関係を示すこととなる2種以上の鉄鉱石等を選択使用する配合が考えられる。例えば、オーストラリア産鉄鉱石のうち、図1に示すような鉄鉱石(A~Z)の1つ以上を配合しかつ必要に応じてベントナイトや生石灰等バインダーや副原料を加えた上で造粒することである。 In producing the non-calcined pellets for reduction according to the present invention, in order to realize the above-mentioned relationship between the highly viscous slag components (Al 2 O 3 +MgO+SiO 2 ) and the total iron (T.Fe) in the non-calcined pellets obtained, it is possible to use a blend of two or more types of iron ores that exhibit the above-mentioned relationship by blending one or more types of iron ores that originally have the above-mentioned component composition. For example, one or more types of iron ores (A to Z) as shown in Fig. 1 are blended from Australian iron ores, and then granulated after adding binders and auxiliary materials such as bentonite and quicklime as necessary.
前述した非焼成ペレットを固体還元炉に装入して還元する上で重要なことは、炉内の高温還元雰囲気において、前記クラスタリングを招かない性状のものにすることであり、そのために本発明では特に、LOI(Loss on Ignition:強熱減量)に着目してその適性値について検討した。即ち、本発明に係る製造方法においては、前記LOI(強熱減量)値が5%以上となるように、図1に示すような鉄鉱石(A~Z)のうちからその幾つかを選択使用(配合)してこのLOI≧5%を満たすようにすれば、クラスタリングをより効果的に低減することができる。その理由は、LOIが還元炉内で加熱されて解離・気化してペレットの外に散逸する際に、ペレット内に残った鉱物相の体積が収縮し、鉱物相と鉱物相の間に空隙を生じるためである。 When the non-calcined pellets described above are charged into a solid reduction furnace and reduced, it is important to make them have properties that do not cause the clustering in the high-temperature reduction atmosphere in the furnace. For this reason, in the present invention, the LOI (loss on ignition) was particularly focused on and its appropriate value was examined. That is, in the manufacturing method according to the present invention, if some of the iron ores (A to Z) shown in FIG. 1 are selected and used (blended) so that the LOI (loss on ignition) value is 5% or more, and this LOI ≧ 5% is satisfied, clustering can be reduced more effectively. The reason is that when the LOI is heated in the reduction furnace, dissociated and vaporized, and dissipated outside the pellets, the volume of the mineral phase remaining in the pellets shrinks, and voids are generated between the mineral phases.
次に、本発明に係る製造方法においては、前述した鉄含有原料としてのLOI≧5%を実現するために、使用する鉄鉱石等については、予めこれを脱結晶水処理等の事前処理を施すことにより、LOI≦2%にすることが好ましい。その理由は、原料鉄鉱石等の鉄含有原料の多くが多くの結晶水を含んでいるため、造粒時に該結晶水に起因して発生する水蒸気によってペレットが破裂することが多く、そのため昇温をゆっくりせざるを得なくなるからである。 Next, in the manufacturing method according to the present invention, in order to achieve an LOI of ≥ 5% for the iron-containing raw material, it is preferable to set the LOI of the iron ore, etc. used to ≤ 2% by performing a pre-treatment such as a crystal water removal treatment. The reason for this is that many iron-containing raw materials such as raw iron ore contain a lot of crystal water, and the pellets often burst due to the water vapor generated by the crystal water during granulation, which makes it necessary to raise the temperature slowly.
(実施例)
〈例1〉
この実施例(比較例を含む)では、還元用非焼成ペレットのT.Feと高粘性のスラグ成分(Al2O3+MgO+SiO2)との関係が固体還元炉内でのクラスタリングにどのような影響を及ぼすのかを明らかにするものである。
(Example)
Example 1:
In this example (including comparative examples), it is clarified how the relationship between the T.Fe of the non-sintered pellets for reduction and the highly viscous slag components (Al 2 O 3 +MgO+SiO 2 ) affects the clustering in a solid reduction furnace.
実施に当たって使用した鉄含有原料すなわち鉄鉱石については、主として図1に示すオーストラリア産鉄鉱石の一種以上、及び必要に応じて副原料と試薬(市販のAl2O3試薬など)を用いた配合を行った。その配合例を表1に示す。
5質量%のセメントを添加して所定の成分となるように配合し、その後ボールミルで粉砕し、ペレタイザーを使って水分を加えながら9~16mmの大きさに造粒した後、2週間養生することで非焼成ペレットを製造した。
The iron-containing raw material, i.e., iron ore, used in the experiment was a blend of one or more of the Australian iron ores shown in Figure 1, and auxiliary raw materials and reagents (such as commercially available Al2O3 reagent) as necessary. An example of the blend is shown in Table 1.
5% by mass of cement was added to the mixture to obtain the specified composition, which was then pulverized in a ball mill and granulated to sizes of 9 to 16 mm using a pelletizer while adding moisture. The mixture was then cured for two weeks to produce non-fired pellets.
前述したオーストラリア産原料の一種以上(図1に例示するA~Z)を含む、上記表1に示すような配合に係る全原料をボールミルで粉砕し、次いでペレタイザーで水分を加えながら9~16mmの大きさのものに造粒した。得られた造粒後の非焼成ペレットを2週間養生することで非焼成ペレットを得た。得られた表1に示す各非焼成ペレットについて、クラスタリング指数を使って評価した。 All raw materials for the composition shown in Table 1 above, including one or more of the Australian raw materials mentioned above (A to Z shown in Figure 1), were pulverized in a ball mill and then granulated into pellets with a size of 9 to 16 mm while adding moisture in a pelletizer. The resulting granulated non-calcined pellets were cured for two weeks to obtain non-calcined pellets. Each of the obtained non-calcined pellets shown in Table 1 was evaluated using the clustering index.
(クラスタリング評価試験)
100φの縦型円筒炉に試料を500g装入し、N2雰囲気中で1000℃まで昇温し、1000℃になったら還元ガス:24L/min、H2:N2=20:80(vol%)、荷重1kg/cm2で3時間保持した後、N2雰囲気中で冷却し、還元鉄を製造した。その後、非焼成ペレット単体の最大サイズである16mmで篩った後、重量(Wa(g))を測定し、篩上をI型試験機〔円筒形容器(132mmφ×700mL)〕に入れ、回転速度30rpmで5分間回転させた後、16mmで篩った量Wb(g)を評価した。
(Clustering evaluation test)
500 g of the sample was placed in a 100φ vertical cylindrical furnace and heated to 1000°C in a N2 atmosphere. When the temperature reached 1000°C, the sample was held for 3 hours with reducing gas: 24 L/min, H2 : N2 = 20:80 (vol%) and a load of 1 kg/ cm2 , and then cooled in a N2 atmosphere to produce reduced iron. The pellets were then sieved through a 16 mm sieve, which is the maximum size of a single unsintered pellet, and the weight (Wa (g)) was measured. The sieved pellets were placed in a type I testing machine [cylindrical container (132 mmφ x 700 mL)] and rotated at a rotation speed of 30 rpm for 5 minutes, and the amount Wb (g) sieved through the 16 mm sieve was evaluated.
なお、下記表2は、表1の実施例1,2で得られた非焼成ペレットの成分組成を示すものである。 The following Table 2 shows the composition of the non-sintered pellets obtained in Examples 1 and 2 in Table 1.
〈例2〉
〈例1〉の表1(クラスタリング評価試験)で示した比較例2と同じ方法で得られた還元鉄(Waを測定した時点のサンプル)を粉砕し、粒径3mm以下としたものを比較例2の焼成前の原料と混合し、それを用いて実施例の方法で非焼成ペレットを製造した。2週間養生後の非焼成ペレットについて圧壊強度を測定した。
Example 2:
Reduced iron (sample at the time of measuring Wa) obtained by the same method as in Comparative Example 2 shown in Table 1 (clustering evaluation test) in Example 1 was pulverized to a particle size of 3 mm or less, which was mixed with the raw material before sintering in Comparative Example 2, and non-sintered pellets were produced using this by the method of the Example. The crushing strength of the non-sintered pellets after 2 weeks of curing was measured.
その結果を下記表3に示す。表3中の「M.Fe」は、還元鉄に含まれるM.Feに由来するものであり、実施例10~12は、M.Fe=78mass%の還元鉄を用いたものであり、実施例13は、M.Fe=80mass%の還元鉄を用いたものである。その結果、M.Feを原料に混合することで、ペレット強度が向上することが分かった。クラスタリングは粉が増加することで促進されてしまうため、非焼成ペレット強度が向上することでクラスタリングの抑制が可能である。また、M.Feを原料に配合することで非焼成ペレットの強度が向上するのは、養生期間中に空気と還元鉄粉が接触し金属鉄が酸化して発熱するために、隣接している粒子同士の接着が促進されるためだと考えらえる。このため、M.Feを原料に配合することによる非焼成ぺレット強度の向上効果は、造粒の2日後から発現し始め、造粒後4週間で強度の上昇はほぼ停止する。 The results are shown in Table 3 below. "M.Fe" in Table 3 is derived from M.Fe contained in the reduced iron, and in Examples 10 to 12, reduced iron with M.Fe = 78 mass% was used, and in Example 13, reduced iron with M.Fe = 80 mass% was used. As a result, it was found that pellet strength was improved by mixing M.Fe into the raw material. Clustering is promoted by increasing the amount of powder, so clustering can be suppressed by improving the strength of the non-sintered pellets. In addition, the reason why the strength of the non-sintered pellets is improved by adding M.Fe to the raw material is thought to be because the reduced iron powder comes into contact with air during the curing period, causing the metallic iron to oxidize and generate heat, which promotes adhesion between adjacent particles. For this reason, the effect of improving the strength of the non-sintered pellets by adding M.Fe to the raw material begins to appear two days after granulation, and the increase in strength almost stops four weeks after granulation.
本発明に係る固体還元非焼成ペレットについては、主として水素ベースの直接還元プロセスなどに適用するために開発した技術であるが、もちろん高炉等で用いる原料としても使用が可能である。
The solid-reduced non-calcined pellets according to the present invention are a technology developed primarily for application in hydrogen-based direct reduction processes, but can also be used as a raw material in blast furnaces, etc.
Claims (5)
記
(Al2O3+MgO+SiO2)/T.Fe≧0.12 ・・・(1)
ただし、Al2O3: 非焼成ペレット中のAl2O3の成分濃度(質量%)
MgO: 非焼成ペレット中のMgOの成分濃度(質量%)
SiO2: 非焼成ペレット中のSiO2の成分濃度(質量%)
T.Fe: 非焼成ペレット中のT.Feの成分濃度(質量%) A method for producing non-sintered pellets for reduction, in which the ratio of high-viscosity slag components ( Al2O3 + MgO + SiO2 ) to total Fe (T.Fe) satisfies the following formula (1) , characterized in that an iron-containing raw material is used that is blended so that the average LOI (loss on ignition) is 5% or more, and that has been pre-treated to remove water of crystallization so that the average LOI (loss on ignition) is 2% or less .
(Al 2 O 3 +MgO+SiO 2 )/T. Fe≧0.12 (1)
Where, Al 2 O 3 : component concentration of Al 2 O 3 in the non-sintered pellet (mass %)
MgO: MgO component concentration (mass%) in unsintered pellets
SiO2 : SiO2 component concentration in the unsintered pellet (mass%)
T.Fe: Component concentration (mass%) of T.Fe in unsintered pellets
記
(Al2O3+MgO+SiO2)/T.Fe≧0.15 ・・・(2)
ただし、Al2O3: 非焼成ペレット中のAl2O3の成分濃度(質量%)
MgO: 非焼成ペレット中のMgOの成分濃度(質量%)
SiO2: 非焼成ペレット中のSiO2の成分濃度(質量%)
T.Fe: 非焼成ペレット中のT.Feの成分濃度(質量%) The method for producing non- sintered pellets for reduction according to claim 1, characterized in that the ratio of high viscous slag components ( Al2O3 +MgO+ SiO2 ) to total Fe (T.Fe) satisfies the following formula (2):
(Al 2 O 3 +MgO+SiO 2 )/T. Fe≧0.15 (2)
Where, Al 2 O 3 : component concentration of Al 2 O 3 in the non-sintered pellet (mass %)
MgO: MgO component concentration (mass%) in unsintered pellets
SiO2 : SiO2 component concentration in the unsintered pellet (mass%)
T.Fe: Component concentration (mass%) of T.Fe in unsintered pellets
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