JP2013133513A - Method for producing agglomerated ore - Google Patents
Method for producing agglomerated ore Download PDFInfo
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- JP2013133513A JP2013133513A JP2011285452A JP2011285452A JP2013133513A JP 2013133513 A JP2013133513 A JP 2013133513A JP 2011285452 A JP2011285452 A JP 2011285452A JP 2011285452 A JP2011285452 A JP 2011285452A JP 2013133513 A JP2013133513 A JP 2013133513A
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- 238000004519 manufacturing process Methods 0.000 title claims abstract description 23
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 116
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 87
- 230000003647 oxidation Effects 0.000 claims abstract description 62
- 229910052742 iron Inorganic materials 0.000 claims abstract description 55
- 239000002994 raw material Substances 0.000 claims abstract description 53
- 238000010304 firing Methods 0.000 claims abstract description 29
- 239000000428 dust Substances 0.000 claims abstract description 16
- 239000008188 pellet Substances 0.000 claims abstract description 12
- 239000002245 particle Substances 0.000 claims abstract description 10
- 230000001590 oxidative effect Effects 0.000 claims abstract description 8
- 238000007873 sieving Methods 0.000 claims abstract description 8
- 239000000463 material Substances 0.000 claims description 14
- 238000000034 method Methods 0.000 claims description 13
- 229910052500 inorganic mineral Inorganic materials 0.000 claims description 7
- 239000011707 mineral Substances 0.000 claims description 7
- -1 sintered ore Substances 0.000 claims description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 26
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 abstract description 17
- 238000005245 sintering Methods 0.000 abstract description 15
- 229910000831 Steel Inorganic materials 0.000 abstract description 2
- 238000002425 crystallisation Methods 0.000 abstract description 2
- 230000008025 crystallization Effects 0.000 abstract description 2
- 239000010959 steel Substances 0.000 abstract description 2
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 abstract 1
- 239000000155 melt Substances 0.000 abstract 1
- 239000007789 gas Substances 0.000 description 43
- 239000013078 crystal Substances 0.000 description 24
- 239000000843 powder Substances 0.000 description 22
- 238000006243 chemical reaction Methods 0.000 description 6
- 239000000571 coke Substances 0.000 description 6
- 238000001354 calcination Methods 0.000 description 5
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 4
- 239000000701 coagulant Substances 0.000 description 4
- 235000010755 mineral Nutrition 0.000 description 4
- 238000005054 agglomeration Methods 0.000 description 3
- 230000002776 aggregation Effects 0.000 description 3
- 230000035484 reaction time Effects 0.000 description 3
- 238000005979 thermal decomposition reaction Methods 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 235000019738 Limestone Nutrition 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000000292 calcium oxide Substances 0.000 description 2
- 235000012255 calcium oxide Nutrition 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229910052595 hematite Inorganic materials 0.000 description 2
- 239000011019 hematite Substances 0.000 description 2
- 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 2
- 239000006028 limestone Substances 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000007858 starting material Substances 0.000 description 2
- 230000004931 aggregating effect Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- RHZUVFJBSILHOK-UHFFFAOYSA-N anthracen-1-ylmethanolate Chemical compound C1=CC=C2C=C3C(C[O-])=CC=CC3=CC2=C1 RHZUVFJBSILHOK-UHFFFAOYSA-N 0.000 description 1
- 239000003830 anthracite Substances 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000001112 coagulating effect Effects 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000009770 conventional sintering Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000003111 delayed effect Effects 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
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
- 230000003179 granulation Effects 0.000 description 1
- 230000020169 heat generation Effects 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
- 239000003915 liquefied petroleum gas Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000011812 mixed powder Substances 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
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Abstract
Description
本発明は、高炉原料などとして使用できる塊成鉱の製造方法に関するものである。 The present invention relates to a method for producing agglomerated ore that can be used as a blast furnace raw material.
一般に、製鉄所の製鉄工程では、鉄鉱石等の主原料に対し、コークス等の炭材、石灰石等の副原料が多量に用いられる。例えば、高炉製銑法の主原料としては、現在、塊鉄鉱石、焼結鉱およびペレット等が使用されているが、その大部分は焼結鉱である。その焼結鉱の原料としては、鉄鉱石粉の他、焼結鉱篩下粉、製鉄所内で発生したダストやミルスケール等の回収粉、石灰石およびドロマイトなどの含ＣａＯ系副原料、生石灰等の造粒助剤、コークス粉や無煙炭などの凝結材が用いられている。 Generally, in a steelmaking process of a steel mill, a large amount of carbonaceous materials such as coke and auxiliary materials such as limestone are used with respect to main raw materials such as iron ore. For example, as the main raw material of the blast furnace ironmaking method, massive iron ore, sintered ore, pellets and the like are currently used, but most of them are sintered ore. The raw materials for the sintered ore include iron ore powder, sinter ore sieving powder, recovered powder such as dust and mill scale generated in steelworks, CaO-containing auxiliary raw materials such as limestone and dolomite, and quick lime. Condensation agents such as grain auxiliaries, coke powder and anthracite are used.
なかでも鉄鉱石粉については、従来、赤鉄鉱石等の脈石分の少ない高品位鉄鉱石が使用されているが、豪州産のものを中心にこのような鉄鉱石については枯渇しつつある。このことから、近年では、その代替として結晶水を多量に含むピソライト鉱石やマラマンバ鉱石のような高結晶水鉄鉱石の使用量が増加している。こうした高結晶水含有鉄鉱石粉を焼結用原料として使用するには、該鉄鉱石粉中の結晶水の熱分解のために、熱の供給源となる凝結材（粉コークス等）の使用量が増大するという問題があった。また、通常の原料造粒用水分に加えて、結晶水として水を含有しているため、原料として持ち込む水分量が増加し、このことが原料充填層の湿潤帯の拡張を招いて焼結機の生産性を低下させるというという問題もあった。 Among them, high-grade iron ore with a small amount of gangue such as hematite ore has been used for iron ore powder, but such iron ore is being depleted mainly in Australia. For this reason, in recent years, as an alternative, the amount of high crystalline hydrous iron ore such as pisolite ore and maramamba ore containing a large amount of crystal water has increased. In order to use such high crystal water containing iron ore powder as a raw material for sintering, the amount of aggregating material (powder coke, etc.) used as a heat source increases due to thermal decomposition of the crystal water in the iron ore powder. There was a problem to do. Further, since water is contained as crystal water in addition to normal raw material granulation moisture, the amount of moisture brought in as raw material increases, which leads to expansion of the wet zone of the raw material packed layer, and the sintering machine. There was also a problem of lowering productivity.
このような問題に対し従来、特許文献１では、結晶水を含む鉄鉱石については、これを予め還元処理して予備還元鉱石とした上で、これを焼結鉱製造用原料として使用する焼結鉱の製造方法を提案している。それは、この従来方法によれば高結晶水鉄鉱石を使用するときの上述した問題が解消できるからである。
Conventionally, with respect to such a problem, in
しかしながら、上記従来技術については、なお、次のような課題があった。即ち、特許文献１に開示されている焼結鉱の製造方法の場合、前記予備還元鉱石の酸化による発熱量を熱源として利用することができるので、凝結材の使用量を減らすことができるという利点はあるものの、焼結機の反応温度自体を低下させることにはならず、多量の熱の投入および融液量の増大を阻止することまではできていない。
However, the above prior art still has the following problems. That is, in the case of the method for producing sintered ore disclosed in
また、要するにこの特許文献１に開示の技術では、還元性の低い高炉ガスを部分燃焼させたガスを使って鉄鉱石を予備還元しているため、このプロセスから排出される排ガスは還元性がさらに低下したものとなるので、他の用途に転用することができなくなるという問題がある。つまり、この従来技術の場合、予備還元鉱石を焼結鉱製造用原料とするところに大きな問題があると考えられる。
In short, in the technology disclosed in
本発明の主たる目的は、酸化鉄含有原料を低温で焼成しても高炉用原料などとして十分な強度をもつ塊成鉱を有利に製造することができる方法を提案することにある。 The main object of the present invention is to propose a method capable of advantageously producing an agglomerate having sufficient strength as a raw material for a blast furnace even if the iron oxide-containing raw material is fired at a low temperature.
本発明の他の目的は、低酸化度鉱石を焼結鉱製造用原料としてではなく、高炉用原料などとして用いられる塊成鉱にすることで、これを焼結機で使用するときの上記の課題を払拭することにある。 Another object of the present invention is to make the low oxidation degree ore as an agglomerate used as a raw material for a blast furnace, not as a raw material for producing a sintered ore, and when using this in a sintering machine, It is to wipe out the problem.
従来技術が抱えている上記課題の解決に向けて鋭意研究を重ねた結果、発明者らは、酸化度の大きい鉄鉱石を一旦還元して低酸化度の鉱石とし、次いでこれを酸化処理して焼結機にではなく、低温の焼成炉に装入し、酸素を含む酸化性雰囲気下の８５０℃程度以下の温度域で酸化処理（低酸化度→高酸化度）する際の発熱を伴う焼成反応によって塊成鉱を製造にするという方法を開発し、本発明を完成させた。 As a result of intensive research aimed at solving the above-mentioned problems of the prior art, the inventors reduced iron ore with a high degree of oxidation to a low degree of ore and then oxidized it. Calcination with heat generated in a low-temperature firing furnace, not in a sintering machine, during oxidation treatment (low oxidation degree → high oxidation degree) in a temperature range of about 850 ° C. or lower in an oxidizing atmosphere containing oxygen A method of producing agglomerates by reaction was developed and the present invention was completed.
即ち、本発明は、鉄（ＦｅＯｘｏ）の酸化度を示すｘｏが０〜１．３６である低酸化度鉄源原料の一種以上を直接もしくは混合−成形した上で、これらを酸化性雰囲気下にある焼成炉内に装入して８５０℃以下の温度にて低温焼成することを特徴とする塊成鉱の製造方法を提案する。 That is, in the present invention, one or more of low-oxidation degree iron source raw materials whose xo indicating the oxidation degree of iron (FeOxo) is 0 to 1.36 are directly or mixed and formed, and then these are put in an oxidizing atmosphere. The present invention proposes a method for producing agglomerated ore, which is charged into a firing furnace and fired at a low temperature of 850 ° C. or lower.
なお、本発明方法においては、
（１）前記低酸化度鉄源原料は、Ｆｅ２Ｏ３あるいはＦｅＯ相当のものに還元された低酸化度鉄鉱石の他、少なくとも同程度以下の酸化度をもつミルスケール、転炉ガスやＯＧガスの如き製鉄ダスト、焼結鉱およびペレットのうちから選ばれるいずれか１種以上であること、
（２）前記低酸化度鉄源原料は、少なくとも１０ｍａｓｓ％以上の低酸化度鉱石を含むこと、
（３）前記焼成温度は２５０℃以上とすること、
（４）焼成後の篩分けによって、平均粒径：５ｍｍ〜３０ｍｍの塊成鉱とすること、
がより好ましい解決手段になると考えられる。
In the method of the present invention,
(1) The low-oxidation iron source material is a low-oxidation iron ore reduced to an equivalent to Fe 2 O 3 or FeO, as well as a mill scale, converter gas or OG having at least the same or lower oxidation degree. Any one or more selected from iron-made dust such as gas, sintered ore, and pellets;
(2) The low-oxidation degree iron source material contains at least 10 mass% or more low-oxidation degree ore,
(3) The firing temperature is 250 ° C. or higher.
(4) By sieving after calcination, an agglomerate with an average particle diameter of 5 mm to 30 mm,
Is considered to be a more preferable solution.
上述したように構成される本発明によれば、次のような効果が期待できる。例えば、結晶水を多く含むような鉄鉱石であっても、これをまず還元したりして一定の低酸化度のものにした場合は、焼結機による処理を経ることなく直接、高炉用原料となる塊成鉱にすることができる。そのため、低品質の鉄鉱石でも焼結機の生産性に影響を及ぼすようなことなく、高炉用原料にすることができる。また、本発明においては、高炉用原料の製造のために、低酸化度鉱石などの低酸化度鉄源原料を酸化発熱させることにより生じる熱を利用するので比較的低温でも、即ち、少ない熱エネルギーの供給でも焼成することができるので、熱エネルギー消費が少なく、従って、高強度の高炉用原料を安価に製造することができるようになる。 According to the present invention configured as described above, the following effects can be expected. For example, even if iron ore containing a lot of crystal water is reduced to a certain low oxidation degree by first reducing it, the raw material for blast furnace is directly used without any treatment by a sintering machine. Can be agglomerated ore. Therefore, even a low-quality iron ore can be used as a raw material for a blast furnace without affecting the productivity of the sintering machine. In the present invention, the heat generated by oxidizing and heat-producing low-oxidation degree iron source raw materials such as low-oxidation degree ores is used for the production of blast furnace raw materials, so even at a relatively low temperature, that is, low thermal energy. Can be baked even if it is supplied, the heat energy consumption is small, and therefore, a high-strength blast furnace raw material can be manufactured at low cost.
以下に、本発明の構成の詳細を説明する。本発明に係る塊成鉱の製造方法においては、出発材料である主要原料として、酸化度が一定レベルの低酸化度鉱石を主に用いる他、酸化度が同レベル以下である焼結鉱やペレット、ミルスケール、製鉄ダスト、還元鉄粉等の１種以上を必要に応じて混合して用いる。特に、一定品質のものを安定供給できるという点では、前記低酸化度鉱石の使用は有用である。 Details of the configuration of the present invention will be described below. In the method for producing agglomerated ore according to the present invention, as a main raw material that is a starting material, a low-oxidized ore having a certain level of oxidation is mainly used, and sintered ores and pellets having an oxidation level equal to or lower than the same level. 1 type or more of mill scale, iron-making dust, reduced iron powder, etc. are mixed and used as needed. In particular, the use of the low oxidation degree ore is useful in that a constant quality can be stably supplied.
例えば、前記低酸化度鉱石としては、ピソライト鉱石やマラマンバ鉱石などの結晶水を多量（３〜１５ｍａｓｓ％）に含む高結晶水鉄鉱石を予備還元炉に装入し、これを製鉄所で自生する還元ガスを使って還元することによって、まず、低酸化度鉱石にする。次いで、その低酸化度鉱石を必要に応じて他の原料やコークス粉等を加えた上で混合−成形（造粒）し、これを焼成炉内に移し、酸化性雰囲気下において８５０℃以下の温度にて焼成し、必要に応じて篩分け処理することで、塊状の高炉用原料鉱石（塊成鉱）とする方法である。 For example, as the low-oxidation ore, a high-crystal water ore containing a large amount (3 to 15 mass%) of crystal water such as pisolite ore or maramamba ore is charged into a prereduction furnace and is spontaneously generated at a steelworks. First, it is converted to low oxidation ore by reducing with reducing gas. Next, the low oxidation degree ore is mixed and formed (granulated) after adding other raw materials, coke powder, etc., if necessary, and transferred to a firing furnace, and it is 850 ° C. or lower in an oxidizing atmosphere. It is a method of making a raw material ore for a blast furnace (agglomerated ore) by firing at a temperature and subjecting to a sieving treatment as necessary.
本発明においては、代表的には高炉用原料となる塊成鉱を製造するのに、出発原料として少なくとも前記低酸化度鉱石を用いる。それは、通常の鉄鉱石や高結晶水鉄鉱石を還元した鉱石を、焼成時に酸化性雰囲気下に置くと、低酸化度である故に反応時に酸化発熱、これにより８５０℃以下という従来の焼結プロセスに比べて相対的に低い温度でも十分な焼成が可能になるからである。以下、本発明方法について、さらに詳述する。 In the present invention, typically, at least the low-oxidation ore is used as a starting material for producing agglomerated minerals as blast furnace raw materials. It is a conventional sintering process in which ores obtained by reducing ordinary iron ore and high crystal hydrous iron ore in an oxidizing atmosphere during firing have a low oxidation degree and thus generate heat of oxidation during the reaction, resulting in 850 ° C or less. This is because sufficient firing is possible even at a relatively low temperature. Hereinafter, the method of the present invention will be described in further detail.
（１）原料の調整
従来、塊成鉱製造プロセスなどで使用されている原料としては、８ｍｍ程度以下の赤鉄鉱石や結晶水を含む多く鉄鉱石粉であるピソライト鉱石（結晶水８ｍａｓｓ％）やマラマンバ鉱石（結晶水３ｍａｓｓ％）のような高結晶水鉄鉱石の使用が可能であるが、これらについては、予め予備還元して低酸化度鉱石（予備還元鉱石）にする必要がある。
(1) Preparation of raw materials Conventionally, raw materials used in the agglomerate manufacturing process and the like include pisolite ores (crystal water 8 mass%) and maramamba, which are iron ore powders containing about 8 mm or less and a large amount of iron ore powder. It is possible to use a high crystallinity iron ore such as ore (
それは上述したように、高結晶水含有鉱石粉を、従来の焼結鉱製造プロセスの原料として使用すると、鉄鉱石粉中の結晶水の熱分解に熱が必要になるため、熱の供給源である凝結材の使用量が増大するという問題があったからである。この点、この高結晶水鉄鉱石を予め還元性ガスを用いて還元すると、還元に適する温度においては酸化鉄が還元されて低酸化度鉱石に変化する。本発明では、このようにして得られた低酸化度鉱石を、低温で酸化焼成する際の酸化発熱を利用して高炉用原料として好適な塊成鉱とする方法である。 As described above, when ore powder containing high crystal water is used as a raw material for the conventional sinter production process, heat is required for the thermal decomposition of crystal water in iron ore powder, which is a source of heat. This is because there is a problem that the use amount of the coagulant increases. In this regard, when this high crystalline hydrous ore is previously reduced using a reducing gas, the iron oxide is reduced to a low oxidation degree ore at a temperature suitable for the reduction. In the present invention, the low oxidation degree ore obtained as described above is a method of making an agglomerate suitable as a raw material for a blast furnace by utilizing oxidation heat generated during oxidation firing at a low temperature.
なお、高結晶水鉄鉱石粉を還元するための予備還元炉としては、シャフト炉やロータリーキルンおよび流動層還元炉などの使用が可能である。なお、この予備還元炉内には、還元性ガスを導入して前記鉱石の還元処理を行なう。 A shaft furnace, a rotary kiln, a fluidized bed reduction furnace, or the like can be used as a pre-reduction furnace for reducing high-crystal water ore powder. In this preliminary reduction furnace, a reducing gas is introduced to reduce the ore.
前記還元性ガスとしては、転炉ガスや高炉ガス、コークス炉ガス、天然ガス、液化石油ガス等のいずれか１種以上のガスが使用できる。これらの還元性ガスは、鉄鉱石の還元に必要な温度（通常、５００℃以上）まで昇温する必要があるが、高温の転炉ガスを使用すれば、ガスの顕熱を有効に利用することができるため、特に好ましい。通常、転炉ガスは一旦、除塵、冷却して使用されるが、予備還元炉では、転炉ガス除塵時の転炉ダストも低酸化度鉱石を製造するための原料として使用できるので、除塵、冷却の必要がない。さらに、ピソライト鉱石またはマラマンバ鉱石などに含まれる結晶水は、３５０℃付近から分解を始めるので、５００℃以上の温度で還元処理を行なうことで結晶水も同時に分解、除去することが可能である。鉄鉱石は還元雰囲気で１２００℃以上に加熱すると部分的に溶融して粒子同士が融着する可能性があるため、予備還元炉では１２００℃以下の温度で還元処理を行なうことが好ましい。 As the reducing gas, one or more gases such as converter gas, blast furnace gas, coke oven gas, natural gas, and liquefied petroleum gas can be used. These reducing gases need to be heated to a temperature required for the reduction of iron ore (usually 500 ° C. or higher), but if a high-temperature converter gas is used, the sensible heat of the gas is effectively utilized This is particularly preferable. Usually, the converter gas is once used after dust removal and cooling, but in the preliminary reduction furnace, the converter dust at the time of dust removal from the converter gas can also be used as a raw material for producing low-oxidation ores. There is no need for cooling. Furthermore, since the crystal water contained in the pisolite ore or maramamba ore starts to be decomposed at around 350 ° C., the crystal water can be decomposed and removed at the same time by performing a reduction treatment at a temperature of 500 ° C. or higher. When iron ore is heated to 1200 ° C. or higher in a reducing atmosphere, it may partially melt and the particles may be fused together. Therefore, it is preferable to perform the reduction treatment at a temperature of 1200 ° C. or lower in the preliminary reduction furnace.
ところで、転炉ガスや高炉ガスは、ＣＯガス濃度に対してＣＯ２ガス濃度が高いものの、通常、ウスタイト(ＦｅＯ)程度まで還元する能力がある。従って、転炉ガスや高炉ガスを用いてピソライト鉱石またはマラマンバ鉱石などの結晶水を含む鉄鉱石を予備還元炉で還元すると、結晶水が除去されると同時に、製造条件によっては一部に金属鉄を含む場合もあるが、主としてマグネタイト(Ｆｅ３Ｏ４)とウスタイトにまで還元された低酸化度鉱石とすることができる。 Meanwhile, converter gas and blast furnace gas, although CO 2 gas concentration for CO gas concentration higher, typically, is capable of reducing the extent wustite (FeO). Therefore, when iron ore containing crystal water such as pisolite ore or maramamba ore is reduced in a prereduction furnace using converter gas or blast furnace gas, the crystal water is removed, and at the same time, depending on the production conditions, part of the metal iron In some cases, the low-oxidation ore is reduced mainly to magnetite (Fe 3 O 4 ) and wustite.
本発明において、前記予備還元炉で用いる予備還元用ガスとしては、還元ガス中のＨ２濃度（Ｈ２：ｖｏｌ．％）、Ｈ２Ｏ濃度（Ｈ２Ｏ：ｖｏｌ．％）、ＣＯ濃度（ＣＯ：ｖｏｌ．％）、およびＣＯ２濃度（ＣＯ２：ｖｏｌ．％）とすると、下記（１）式で表わされる酸化度Ｘｇ（−）が０.８以下であるものを用いる。もし、この還元ガスの酸化度Ｘｇ（−）が０．８よりも大きくなると、図５に示すように、焼成温度８００℃において少なくともＦｅ３Ｏ４を生成させるためのガスの還元駆動力が小さいため、予備還元炉での還元の進行が遅くなって、低酸化度鉱石の生産性が低下する。そのため、還元ガスの酸化度Ｘｇは０.８よりも小さいことが好ましい。転炉ガスや高炉ガスの酸化度Ｘｇは、通常、０.１〜０.６程度であり、予備還元炉の還元ガスとして好適に使用できる。
Ｘｇ＝〔（Ｈ２Ｏ ＋ ＣＯ２）／（Ｈ２ ＋ Ｈ２Ｏ ＋ ＣＯ ＋ ＣＯ２）〕ｖｏｌ．％
（１）
In the present invention, the prereduction gas used in the prereduction furnace includes H 2 concentration (H 2 : vol.%), H 2 O concentration (H 2 O: vol.%), CO concentration ( . CO: vol%), and CO 2 concentration (CO 2:. vol When%) to, the following (1) oxidation degree is represented by the formula Xg (- used ones) is 0.8 or less. If the oxidation degree Xg (−) of the reducing gas is larger than 0.8, as shown in FIG. 5, the reduction driving force of the gas for generating at least Fe 3 O 4 at a firing temperature of 800 ° C. is small. Therefore, the progress of the reduction in the preliminary reduction furnace is delayed, and the productivity of the low oxidation degree ore is lowered. For this reason, the oxidation degree Xg of the reducing gas is preferably smaller than 0.8. The degree of oxidation Xg of the converter gas or blast furnace gas is usually about 0.1 to 0.6, and can be suitably used as the reducing gas for the preliminary reduction furnace.
Xg = [(H 2 O + CO 2) / (H 2 + H 2 O + CO + CO 2) ] vol. %
(1)
本発明では、塊成鉱製造用原料として鉄の酸化度ｘｏ（ＦｅＯｘｏ）で０〜１．３６を示す低酸化度鉱石を、例えば、１０ｍａｓｓ％以上、好ましくは３０ｍａｓｓ％以上、より好ましくは４０ｍａｓｓ％以上使用することが好ましい。そして、残部としては、焼結鉱、ペレットやミルスケール、製鉄ダスト（転炉ダストやＯＧダスト等）の如き低酸化度鉄源原料を、必要に応じ混合して用いる。ただし、これらはいずれも、該低酸化度鉱石に求められる前記酸化度：０≦ｘｏ≦１．３６を満足するものであって、後述する低温焼成処理のための原料として好ましい材料である。この酸化度は、より好ましくは、０≦ｘｏ≦１．１０のウスタイトを主とする原料を用いることが望ましい。 In the present invention, a low oxidation degree ore having an oxidation degree of iron xo (FeOxo) of 0 to 1.36 as a raw material for agglomerated mineral production is, for example, 10 mass% or more, preferably 30 mass% or more, more preferably 40 mass%. It is preferable to use the above. And as a remainder, low oxidation iron source materials, such as a sintered ore, a pellet, a mill scale, and iron-making dust (converter dust, OG dust, etc.), are mixed and used as needed. However, all of these satisfy the above-mentioned degree of oxidation required for the low oxidation degree ore: 0 ≦ xo ≦ 1.36, and are preferable materials as raw materials for the low-temperature firing treatment described later. The degree of oxidation is more preferably a raw material mainly composed of wustite with 0 ≦ xo ≦ 1.10.
（２）低温焼成処理
次に、上述した低酸化度鉱石あるいは製鉄ダストやミルスケール等の酸化度０≦ＦｅＯｘｏ≦１．３６の低酸化度鉄源原料は、場合によってはさらに、他の原料（低結晶水鉄鉱石粉や焼結鉱篩下粉、回収粉、副原料および凝結材）と混合して配合原料とし、これをパンペレタイザーやドラムミキサー等にて造粒し、引き続きロータリーキルン等の焼成設備にて８５０℃以下の温度で焼成して塊成鉱とする。
(2) Low-temperature firing treatment Next, the low-oxidation degree iron source raw material having the oxidation degree of 0 ≦ FeOxo ≦ 1.36, such as the above-mentioned low-oxidation ore or iron-making dust or mill scale, may further include other raw materials ( Low crystal hydrous iron ore powder, sintered ore sieving powder, recovered powder, auxiliary material and coagulating material) are mixed into raw material, which is granulated with a pan pelletizer, drum mixer, etc., followed by baking equipment such as a rotary kiln And calcined at a temperature of 850 ° C. or lower to form agglomerated ore.
こうして得られる塊成鉱は、篩分けし、篩上のものを高炉原料として適した粒径の成品塊成鉱とする一方、篩下のものを篩下粉として分別する。この篩下粉は、既に結晶水が除去された状態であるので、この焼成処理プロセスの原料として使用してもよいし、焼結鉱製造時の焼結鉱篩下粉に混合して使用してもよい。 The agglomerated mineral thus obtained is sieved, and the material on the sieve is made into a product agglomerated with a particle size suitable as a blast furnace raw material, while the material under the sieve is fractionated as undersieving powder. Since this sieving powder is already in a state in which water of crystallization has been removed, it may be used as a raw material for this firing treatment process, or may be used by mixing with the sinter ore sieving powder during the production of sinter. May be.
このように、低酸化度鉱石、その他の酸化度ｘｏが０〜１．３６を示す低酸化度鉄源原料を造粒した後、ロータリーキルン等の焼成設備内に装入して加熱して塊成鉱とするが、この処理において、酸化度ｘｏが０〜１．３６の低酸化度鉄原料を使用する利点は、焼成設備内では酸化性の高温ガス雰囲気にさらされるので、該原料中のＦｅ３Ｏ４やＦｅＯが酸化されて自身発熱することにある。この発熱により、該原料粒子自体の温度が上昇し、粒子同士が適度に結合し合い、塊成化する。従来技術である焼結プロセスの処理では、原料層内温度を１２００℃以上に保持することで焼結反応を進行させるが、本発明では、低酸化度鉄源原料粒子自身の酸化発熱により、自発的に粒子温度が高くなるため、雰囲気温度は８５０℃以下と低い温度であっても反応が進行するようになる。 Thus, after granulating the low oxidation degree ore and the other low oxidation degree iron source raw material having an oxidation degree xo of 0 to 1.36, the raw material is charged into a kiln such as a rotary kiln and heated to agglomerate. In this treatment, the advantage of using the low oxidation iron raw material having an oxidation degree xo of 0 to 1.36 is exposed to an oxidizing high-temperature gas atmosphere in the firing facility. 3 O 4 and FeO are oxidized to generate heat. Due to this heat generation, the temperature of the raw material particles themselves increases, and the particles are appropriately bonded and agglomerated. In the prior art sintering process, the sintering reaction proceeds by maintaining the temperature in the raw material layer at 1200 ° C. or higher. In particular, since the particle temperature becomes high, the reaction proceeds even if the ambient temperature is as low as 850 ° C. or less.
なお、低酸化度鉱石については、還元率が高いほど、酸化時の単位質量当たりの発熱量が大きいので、低酸化度鉱石の使用量が一定の場合、低酸化度鉱石の還元率が高いほど酸化反応が速やかに進行するため好ましいと言える。さらに、低酸化度鉱石を製造する工程で鉄鉱石中の結晶水が除去されているので、焼成時（塊成化時）に結晶水の分解に必要な熱を添加する必要がなくなる。 For low-oxidation ores, the higher the reduction rate, the greater the calorific value per unit mass during oxidation, so if the amount of low-oxidation ore used is constant, the higher the reduction rate of the low-oxidation ore, It can be said that it is preferable because the oxidation reaction proceeds rapidly. Furthermore, since the crystal water in the iron ore has been removed in the process of producing the low oxidation degree ore, it is not necessary to add heat necessary for the decomposition of the crystal water during firing (at the time of agglomeration).
これに対しもし、図２に示すように、０≦ｘｏ≦０．５の酸化度をもつ前記低酸化度鉄源原料を焼成する時、その雰囲気温度を９００℃と高くすると、却って、酸化反応が速く進行し、擬似粒子表面に緻密なシェルを形成する結果、擬似粒子内部まで酸素が拡散せず、塊成化の反応が十分に進行しなくなる。従って、本発明において、この低酸化度鉄源原料の焼成は、８５０℃以下の温度、好ましくは２５０〜８００℃の温度で行なうことが必要である。 On the other hand, as shown in FIG. 2, when firing the low oxidation iron source material having an oxidation degree of 0 ≦ xo ≦ 0.5, if the ambient temperature is raised to 900 ° C., the oxidation reaction As a result of the rapid progress and formation of a dense shell on the surface of the pseudo particles, oxygen does not diffuse into the pseudo particles and the agglomeration reaction does not proceed sufficiently. Therefore, in the present invention, this low-oxidized iron source material must be fired at a temperature of 850 ° C. or lower, preferably 250 to 800 ° C.
以上の説明から明らかように、例えば、結晶水を含むピソライト鉱石またはマラマンバ鉱石なども一旦低酸化度鉱石にすれば、焼結機以外で塊成化できるので、高炉での原料使用量一定とすれば、焼結機でのピソライト鉱石またはマラマンバ鉱石の使用比率を低下させることができるようになる。その結果、焼結機操業では、結晶水由来の水蒸気の発生量が減少し、かつ結晶水の熱分解に必要な凝結材の使用量低下に伴って、凝結材の燃焼によって形成される高温燃焼領域が減少し、過剰な融液の生成が抑制されるため、焼結層での圧力損失が低下する。このため、焼結機の主排ガス吸引ブロワーの吸引負圧を一定とすると、単位時間当たりの吸引ガス量が増加し、焼結機本体のパレットスピードを増加させることができ、焼結鉱の生産性を向上させるができるという、付随的な効果も生まれる。 As can be seen from the above explanation, for example, once a low-oxidation ore containing a crystallite-containing pisolite ore or maramanba ore can be agglomerated other than by a sintering machine, the amount of raw material used in the blast furnace should be constant. For example, the use ratio of the pisolite ore or maramamba ore in the sintering machine can be reduced. As a result, in the sintering machine operation, the amount of water vapor generated from crystal water is reduced, and the high-temperature combustion formed by the combustion of the coagulant is accompanied by a decrease in the amount of coagulant used for thermal decomposition of crystal water. Since the area is reduced and the formation of excessive melt is suppressed, the pressure loss in the sintered layer is reduced. For this reason, if the suction negative pressure of the main exhaust gas suction blower of the sintering machine is kept constant, the amount of suction gas per unit time increases, the pallet speed of the sintering machine body can be increased, and the production of sintered ore There is also an accompanying effect that can improve sex.
この実施例ではまず、多段流動層にて表１に示す鉄鉱石Ａ、Ｂの還元処理を行なった。即ち、付着水分を５.０ｍａｓｓ％含む鉄鉱石Ａ、Ｂ：２.１０ｋｇを多段流動層に供給し、還元ガスとして９００℃の高炉ガス、転炉ガスを２.５１Ｎｍ３使用した。このとき用いた還元ガスの酸化度Ｘｇは０.５１のものであった。使用した還元ガスの組成を表２に示す。なお、流動層内の雰囲気温度を９００℃±５０℃に保つために０.６９Ｎｍ３の空気を用いて還元ガスを部分燃焼させた。流動層から排出されたガスは３.４１Ｎｍ３であり、排ガス中にはＣＯを４.３ｖｏｌ．％含んでいた。このとき、得られた低酸化度鉱石、すなわち予備還元鉱石Ｃ、Ｄは、１.６９ｋｇであり、還元率は約３０％であった。 In this example, first, iron ores A and B shown in Table 1 were reduced in a multistage fluidized bed. That is, 2.10 kg of iron ore A and B containing 5.0 mass% of adhering moisture was supplied to the multistage fluidized bed, and a blast furnace gas at 900 ° C. and a converter gas of 2.51 Nm 3 were used as the reducing gas. The oxidation degree Xg of the reducing gas used at this time was 0.51. The composition of the reducing gas used is shown in Table 2. In order to maintain the atmospheric temperature in the fluidized bed at 900 ° C. ± 50 ° C., the reducing gas was partially burned using 0.69 Nm 3 of air. The gas discharged from the fluidized bed is 3.41 Nm 3 , and CO in the exhaust gas is 4.3 vol. % Included. At this time, the obtained low oxidation degree ore, ie, the pre-reduction ores C and D, was 1.69 kg, and the reduction rate was about 30%.
（２）このようにして、鉄鉱石Ａ、Ｂを多段流動層で還元し、段数および還元ガスの酸化度Ｘｇを変えて製造した還元率の異なる低酸化度の予備還元鉱石Ｃ、Ｄの分析値を表１に併せて示す。表１には、低酸化度鉱石がヘマタイトまで酸化した場合の発熱量、および焼成実験で使用した粉コークスの発熱量を示す。 (2) Analysis of low-reduction degree pre-reduction ores C and D with different reduction ratios produced by reducing iron ores A and B in a multistage fluidized bed in this way and changing the number of stages and the oxidation degree Xg of the reducing gas The values are also shown in Table 1. Table 1 shows the calorific value when the low oxidation degree ore is oxidized to hematite and the calorific value of the powder coke used in the firing experiment.
（３）次に、混合粉重量当たりの発熱量が一定になるように、鉄鉱石Ａ、Ｂ、低酸化度鉱石Ｃ、Ｄ、ミルスケール、ＯＧダスト、ＲＨＦ発生粉と粉コークスとを表３に示すように配合（１〜５）し、ペレタイザーにて１０〜１５ｍｍの大きさのペレットを作成し、これを電気炉内にて大気雰囲気中、雰囲気温度５００℃で３０分の低温焼成を行なった。このとき得られた塊成鉱の強度を同表に示す。鉄鉱石Ａを用いた例では、この温度（５００℃）では粉コークスを添加しているにもかかわらず焼成せず、塊成鉱が得られなかった。一方、低酸化度鉱石Ｃ、Ｄ、転炉ダストやＯＧダストを配合した例では、いずれの試料についても低温焼成でも高い強度の塊成鉱が得られた。なお、表３に示すとおり、低酸化度鉱石を含む鉱石の平均還元率が高い方が塊成鉱の強度が高くなっていた。 (3) Next, the iron ores A and B, the low oxidation degree ores C and D, the mill scale, the OG dust, the RHF generated powder, and the powder coke so that the calorific value per weight of the mixed powder becomes constant are shown in Table 3. (1-5), and pellets with a size of 10-15 mm are prepared with a pelletizer, and this is baked at a low temperature for 30 minutes at 500 ° C. in an air atmosphere in an electric furnace. It was. The strength of the agglomerate obtained at this time is shown in the same table. In the example using iron ore A, at this temperature (500 ° C.), although the coke was added, it was not fired and no agglomerate was obtained. On the other hand, in the examples in which the low oxidation degree ores C and D, converter dust and OG dust were blended, high strength agglomerated ore was obtained even in low-temperature firing for any sample. In addition, as shown in Table 3, the strength of the agglomerate was higher when the average reduction rate of the ore containing the low oxidation degree ore was higher.
次に、配合例（３）の例について、焼成前後のペレットの断面写真を図３に示す。焼成前には低酸化度鉱石、その他の低酸化度鉄原料（ＯＧダスト）が結合している様子はないが、焼成後には低酸化度鉱石、その他の原料どうしが結合していることがわかる。 Next, regarding the example of formulation example (3), cross-sectional photographs of pellets before and after firing are shown in FIG. Low oxidization ore and other low oxidization iron raw materials (OG dust) do not appear to be bonded before firing, but low oxidization ore and other raw materials are combined after calcination .
上記配合例の原料から作成したペレットについて、焼成温度の影響を調べた。上述した１０〜１５ｍｍの大きさのペレットを作成し、電気炉内にて大気雰囲気中、所定の雰囲気温度で３０分焼成した。図４に焼成温度と塊成鉱の圧潰強度の関係を示す。この図に示すように、２００℃〜９００℃の焼成温度では、いずれの条件でも塊成化していたが、９００℃ではペレット表面に緻密なシェルを形成し、ペレット内部が焼成されていなかった。また、２００℃では、塊成鉱の強度が低くなっているが、反応時間を長くした条件では強度が向上した。したがって、２００℃の条件では、反応時間が３０分では十分でなかったと考えられる。一方、９００℃では、反応時間を長くしても強度が改善されることはなかった。したがって、低酸化度鉱石を焼成する温度としては、２５０℃〜８５０℃、より好ましくは２５０℃〜８００℃が好適であることが確かめられた。 For the pellets prepared from the raw materials of the above blending examples, the influence of the firing temperature was examined. The above-described pellets having a size of 10 to 15 mm were prepared and baked for 30 minutes at a predetermined atmospheric temperature in an air atmosphere in an electric furnace. FIG. 4 shows the relationship between the firing temperature and the crushing strength of the agglomerate. As shown in this figure, at a firing temperature of 200 ° C. to 900 ° C., it was agglomerated under any conditions, but at 900 ° C., a dense shell was formed on the pellet surface, and the inside of the pellet was not fired. Further, at 200 ° C., the strength of the agglomerated ore was low, but the strength was improved under the condition that the reaction time was extended. Therefore, it is considered that the reaction time of 30 minutes was not sufficient under the condition of 200 ° C. On the other hand, at 900 ° C., the strength was not improved even if the reaction time was increased. Therefore, it was confirmed that the temperature for firing the low oxidation degree ore is preferably 250 ° C to 850 ° C, more preferably 250 ° C to 800 ° C.
本発明の技術は、製鉄用、特に高炉用原料として使用される塊成鉱の製造技術として有用であるばかりでなく、その他の鉱石塊成化技術としても利用することができる。 The technique of the present invention is not only useful as a technique for producing agglomerates used as a raw material for iron making, particularly blast furnaces, but can also be used as other ore agglomeration techniques.
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| JP2000226608A (en) * | 1999-02-03 | 2000-08-15 | Nkk Corp | Operation of blast furnace |
| JP2006045600A (en) * | 2004-08-03 | 2006-02-16 | Nippon Steel Corp | Method for producing sintered ore |
| JP2008261016A (en) * | 2007-04-12 | 2008-10-30 | Nippon Steel Corp | Method for manufacturing sintered ore |
| JP4384698B2 (en) * | 2008-04-10 | 2009-12-16 | 新日本製鐵株式会社 | Method for producing sintered ore |
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| JP2000226608A (en) * | 1999-02-03 | 2000-08-15 | Nkk Corp | Operation of blast furnace |
| JP2006045600A (en) * | 2004-08-03 | 2006-02-16 | Nippon Steel Corp | Method for producing sintered ore |
| JP2008261016A (en) * | 2007-04-12 | 2008-10-30 | Nippon Steel Corp | Method for manufacturing sintered ore |
| JP4384698B2 (en) * | 2008-04-10 | 2009-12-16 | 新日本製鐵株式会社 | Method for producing sintered ore |
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