JP2014224295A - Method for producing agglomerated ore - Google Patents
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- 238000004519 manufacturing process Methods 0.000 title claims abstract description 16
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 210
- 229910052742 iron Inorganic materials 0.000 claims abstract description 102
- 239000002994 raw material Substances 0.000 claims abstract description 64
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 60
- 239000002245 particle Substances 0.000 claims abstract description 41
- 230000003647 oxidation Effects 0.000 claims abstract description 38
- 238000010304 firing Methods 0.000 claims abstract description 28
- 239000000463 material Substances 0.000 claims abstract description 25
- 230000001590 oxidative effect Effects 0.000 claims abstract description 9
- 239000008188 pellet Substances 0.000 claims description 21
- 239000000428 dust Substances 0.000 claims description 11
- 238000007873 sieving Methods 0.000 claims description 5
- 229910052500 inorganic mineral Inorganic materials 0.000 claims description 4
- 239000011707 mineral Substances 0.000 claims description 4
- -1 sinter ore sieve Substances 0.000 claims 1
- 238000005245 sintering Methods 0.000 abstract description 24
- 239000008187 granular material Substances 0.000 abstract description 6
- 238000002156 mixing Methods 0.000 abstract description 6
- 239000007858 starting material Substances 0.000 abstract description 4
- 239000000203 mixture Substances 0.000 abstract description 3
- 239000007789 gas Substances 0.000 description 27
- 238000000034 method Methods 0.000 description 17
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 16
- 239000000843 powder Substances 0.000 description 16
- 230000009467 reduction Effects 0.000 description 11
- 230000020169 heat generation Effects 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 5
- 238000005054 agglomeration Methods 0.000 description 4
- 230000002776 aggregation Effects 0.000 description 4
- 238000001354 calcination Methods 0.000 description 4
- 239000000571 coke Substances 0.000 description 4
- 238000009770 conventional sintering Methods 0.000 description 4
- 230000007423 decrease Effects 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 238000005469 granulation Methods 0.000 description 3
- 230000003179 granulation Effects 0.000 description 3
- 230000035484 reaction time Effects 0.000 description 3
- 230000008901 benefit Effects 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 239000011812 mixed powder Substances 0.000 description 2
- 230000035699 permeability Effects 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000001112 coagulating effect Effects 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 239000011361 granulated particle Substances 0.000 description 1
- 229910052595 hematite Inorganic materials 0.000 description 1
- 239000011019 hematite Substances 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
- 239000003915 liquefied petroleum gas Substances 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 238000002203 pretreatment Methods 0.000 description 1
- 230000002269 spontaneous effect Effects 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
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Abstract
Description
本発明は、微粉鉄鉱石含有原料から高炉原料などとして使用できる塊成鉱を直接製造する方法に関する。 The present invention relates to a method for directly producing agglomerated ore that can be used as a blast furnace raw material or the like from a fine iron ore-containing raw material.
高炉の主原料としては、塊鉄鉱石や焼結鉱、ペレット等が使われるが、最も使用量が多いのは焼結鉱である。その焼結鉱は、一般に、シンターフィードと呼ばれる粉鉱石を用いて製造されている。ただし、焼結鉱製造用原料となる粉鉱石、例えば、赤鉄鉱等の脈石分が少なく粒径が適度の大きさである高品位の粉鉱石というのは枯渇しつつある。このことから、近年ではその代替として、もっと粒径の小さいペレットフィードと呼ばれる微粉鉄鉱石の使用が検討されている。 As the main raw material of the blast furnace, massive iron ore, sintered ore, pellets, etc. are used, but the most used amount is sintered ore. The sintered ore is generally manufactured using a fine ore called a sinter feed. However, fine ore, which is a raw material for producing sintered ore, for example, high-grade fine ore with a small particle size such as hematite and small gangue, is being depleted. For this reason, in recent years, the use of fine iron ore called pellet feed having a smaller particle size has been studied as an alternative.
ところで、焼結鉱製造用原料として前記微粉鉄鉱石を使用すると、原料の平均粒径が低下することから焼結機の生産性が低下するという問題がある。そのため、微粉鉄鉱石は、たとえこれを焼結鉱製造用原料として使用する場合であっても事前処理が必要である。 By the way, when the fine iron ore is used as a raw material for producing sintered ore, there is a problem that the productivity of the sintering machine is lowered because the average particle size of the raw material is lowered. Therefore, the fine iron ore needs to be pretreated even when it is used as a raw material for producing sintered ore.
このような問題に対して、従来、特許文献１〜３では、焼結機でより多くの微粉鉄鉱石を使用できるようにするための事前処理方法を提案している。これらの方法は、微粉鉄鉱石を使用するときに問題となる造粒性や強度、生産性の低下を抑制する技術が中心である。
Conventionally,
上記文献に記載の技術については、次のような解決すべき課題があった。それは、これらの技術の場合、微粉鉄鉱石を通常の原料と別工程で造粒することで原料の造粒強化を図り、焼結機に供給する原料粒径の増大を実現して、生産性の低下を防止できるという利点がある。しかし、微粉鉄鉱石を用いて造粒した擬似粒子はそもそも、強度があまり高くないこと、及び粒子毎の強度のバラツキが大きいため、一部の擬似粒子は崩壊してしまい、微粉鉄鉱石を含む焼結原料を用いたときの焼結鉱の生産性低下が不可避である。 The techniques described in the above documents have the following problems to be solved. In the case of these technologies, granulated iron ore is granulated in a separate process from ordinary raw materials, thereby strengthening the granulation of the raw materials and realizing an increase in the raw material particle size supplied to the sintering machine. There is an advantage that it is possible to prevent the deterioration of the above. However, pseudo-particles granulated using fine iron ore are not very strong in the first place, and because there is a large variation in strength between particles, some pseudo particles collapse and contain fine iron ore. It is inevitable that the productivity of the sintered ore is lowered when the sintered raw material is used.
そこで、本発明の目的は、微粉鉄鉱石に低酸化度鉄源原料を加えたものを出発原料とすることにより、焼結鉱製造用造粒原料としてではなく、高炉用原料となる塊成鉱を直接製造することで、焼結機で使用するときに問題となる前記課題を払拭することにある。 Therefore, the object of the present invention is to use a low-oxidized iron source material added to fine iron ore as a starting material, and not as a granulated raw material for sinter ore production, but as an agglomerated raw material for a blast furnace. It is to wipe out the said subject which becomes a problem when using with a sintering machine by manufacturing directly.
また、本発明は、低温で焼成しても高炉用原料として十分な強度をもつ塊成鉱を微粉鉄鉱石から直接製造することができる方法を提案する。 The present invention also proposes a method capable of directly producing agglomerated ore having sufficient strength as a raw material for a blast furnace even when fired at a low temperature, from fine iron ore.
発明者らは、上記課題の解決に向けて鋭意研究を重ねた結果、次のような知見を得た。それは、微粉鉄鉱石等を含む鉄源原料のうち特に低酸化度のものは、これを酸化性雰囲気の下で加熱すると酸化発熱するということである。従って、微粉の塊成化に当たって、焼結機のような高温焼成設備を用いなくても、所謂、加熱雰囲気の温度が８５０℃以下という低温の焼成炉を使用しても、自身が酸化発熱することによって短時間でも十分に焼成させることができるようになる。その結果、微粉鉄鉱石から得た造粒原料を焼結機で高温焼成するときなどの上述した課題を一挙に解決することができるようになる。 As a result of intensive studies aimed at solving the above problems, the inventors have obtained the following knowledge. That is, iron source materials containing fine iron ore and the like, particularly those having a low oxidation degree, generate oxidation heat when heated in an oxidizing atmosphere. Therefore, in the agglomeration of fine powder, even if a high-temperature firing facility such as a sintering machine is not used, even if a so-called low-temperature firing furnace having a heating atmosphere temperature of 850 ° C. or less is used, it generates oxidation heat. As a result, it can be sufficiently fired even in a short time. As a result, the above-described problems such as when the granulated raw material obtained from fine iron ore is fired at a high temperature with a sintering machine can be solved at once.
即ち、本発明は、少なくとも、粒径が２５０μｍ以下の微粉鉄鉱石と鉄（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とを混合してから造粒し、その後、その造粒物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である。 That is, the present invention mixes at least one fine iron ore having a particle size of 250 μm or less and one or more low-oxidation iron source raw materials having an xo of 0 to 1.36 indicating the oxidation degree of iron (FeOxo). And then granulating the granulated product into a firing furnace under an oxidizing atmosphere and firing at a low temperature of 850 ° C. or lower.
なお、上記の構成に係る本発明方法においては、
（１）前記微粉鉄鉱石の含有量は、少なくとも３０ｍａｓｓ％以上であること、
（２）前記低酸化度鉄源原料は、Ｆｅ２Ｏ３あるいはＦｅＯ相当のものに予備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、高炉ガスや転炉ＯＧガス中に含まれる各種製鉄ダスト、焼結鉱篩下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、
（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 according to the above configuration,
(1) The content of the fine iron ore is at least 30 mass% or more,
(2) The low-oxidation iron source material is low-oxidation iron ore that has been pre-reduced to Fe 2 O 3 or FeO equivalent, as well as mill scale, blast furnace gas, It is any one or more selected from among various types of iron-making dust, sinter ore pellets and pellets contained in the furnace OG gas,
(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。
（１）微粉鉄鉱石を焼結機による処理を経ることなく、塊成化して高炉用原料として直接使用することができるようになる。そのため、微粉鉄鉱石を原料とする焼結機の操業時に見られる原料粒径の低下などに起因する焼結生産性の低下を考慮する必要がなくなる。
（２）高炉用原料の製造（塊成化）に当たって、低酸化度鉄源原料の酸化発熱を利用することができるので、比較的低温でも焼成することができ、そのために全体の熱エネルギー消費量が少なくなり、しかも、高強度の高炉用原料を比較的短時間で安価に製造することができる。
According to the present invention configured as described above, the following effects can be expected.
(1) The fine iron ore can be agglomerated without being processed by a sintering machine and used directly as a raw material for a blast furnace. Therefore, it is not necessary to take into account the decrease in sintering productivity due to the decrease in the raw material particle size, etc., seen during operation of a sintering machine using fine iron ore as a raw material.
(2) In the production (agglomeration) of raw materials for blast furnaces, it is possible to use the oxidation heat of low-oxidation iron source raw material, so that it can be fired even at a relatively low temperature, and the total heat energy consumption In addition, a high-strength blast furnace raw material can be produced in a relatively short time at a low cost.
本発明は、図１に示すように、少なくとも微粉鉄鉱石と低酸化度微粉鉄源原料との混合原料を出発原料として、これに必要に応じてコークス粉やバインダー等を加えた上でこれらを混合したのち成形（造粒）し、その後、得られた造粒物を後で詳述する酸化焼成炉内に装入し、酸化性雰囲気下において８５０℃以下という低温で加熱して焼成し、さらに必要に応じて篩分け処理することで、塊状の高炉用原料となる塊成鉱を直接製造する方法である。 In the present invention, as shown in FIG. 1, at least a mixed raw material of fine iron ore and a low oxidation degree fine iron source material is used as a starting material, and coke powder or a binder is added thereto as necessary. After mixing, it is molded (granulated), and then the obtained granulated material is charged into an oxidation baking furnace described in detail later, and heated and baked at a low temperature of 850 ° C. or lower in an oxidizing atmosphere. Furthermore, it is the method of manufacturing directly the agglomerate used as the raw material for blast furnaces by sieving as needed.
このように本発明は、従来の焼結原料用鉄鉱石である平均粒径（積算頻度分布が５０％を示す値）が１０００μｍ超のものを用いるのではなく、少なくとも平均粒径（以下、単に粒径という）が２５０μｍ以下の微粉鉄鉱石を含む混合原料から、焼結過程を経ることなく、高炉用原料となり得る塊成鉱を直接製造する方法である。特に、２５０μｍ以下の粒径の微粉鉄鉱石だけでなく、従来の焼結機でも使用しにくい粒径が６３μｍ以下のペレットフィードや粒径が１０μｍ以下のテーリング鉱などをも出発原料として用い、これに粉状・粒状の低酸化度鉄源原料と混合することにより、その混合原料の造粒物を後工程での焼成時、即ち、これらを酸化性雰囲気下で焼成するとき、該混合原料自身の酸化発熱を導いて、焼成温度が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雰囲気温度でも十分に焼成できるようにする方法である。以下、本発明方法について、各工程に沿って詳述する。 As described above, the present invention does not use a conventional iron ore for sintering raw material having an average particle size (a value indicating an integrated frequency distribution of 50%) exceeding 1000 μm, but at least an average particle size (hereinafter, simply referred to as an iron ore for sintering raw materials). This is a method for directly producing agglomerated ore that can be a raw material for a blast furnace without going through a sintering process from a mixed raw material containing fine iron ore having a particle size of 250 μm or less. In particular, not only fine iron ores with a particle size of 250 μm or less, but also pellet feeds with a particle size of 63 μm or less and tailing ores with a particle size of 10 μm or less, which are difficult to use with conventional sintering machines, are used as starting materials. When mixed with the powdery / granular low-oxidation iron source material, the mixed material itself is granulated at the time of firing in the subsequent step, that is, when these are fired in an oxidizing atmosphere. In this method, the oxidation heat generation is conducted, and the firing temperature can be sufficiently fired even at a relatively low atmospheric temperature as compared with the conventional sintering process in which the firing temperature is 850 ° C. or less. Hereinafter, the method of the present invention will be described in detail along each step.
（１）出発原料の混合調整
本発明で用いる出発原料は、少なくとも（粒径が１０００μｍ超のシンターフィードと呼ばれる粉鉱石を配合してもよい）、粒径：６３μｍ以下のペレットフィードや粒径：１０μｍ以下のテーリング鉱などを含む、粒径が２５０μｍ以下の微粉鉄鉱石と、鉄（ＦｅＯｘｏ）の酸化度を示すｘｏが０〜１．３６である粉状・粒状の低酸化度鉄源原料とを混合して用いる。
(1) Mixing adjustment of starting raw material The starting raw material used in the present invention is at least (a powder ore called a sinter feed having a particle size of over 1000 μm may be blended), a pellet feed or particle size of 63 μm or less in particle size: A fine iron ore having a particle size of 250 μm or less, including a tailing ore of 10 μm or less, and a powdery / granular low-oxidation iron source raw material having a xo of 0 to 1.36 indicating an oxidation degree of iron (FeOxo); Are mixed and used.
一般に、２５０μｍ以下の微粉鉄鉱石あるいは６３μｍ以下のペレットフィードや１０μｍ以下のテーリング鉱を焼結鉱製造プロセスの造粒用原料として使用すると、得られる造粒物の粒径は確実に低下する。そのため、焼結機での操業時に、焼結原料充填層（焼結原料層）の通気性が悪化し、焼結機での生産性が低下するという問題が生じるのは上述したとおりである。 In general, when a fine iron ore of 250 μm or less, a pellet feed of 63 μm or less, or a tailing ore of 10 μm or less is used as a raw material for granulation in a sintered ore production process, the particle size of the obtained granule is surely lowered. For this reason, as described above, the air permeability of the sintered raw material packed layer (sintered raw material layer) deteriorates during the operation in the sintering machine, and the productivity in the sintering machine decreases.
なお、前記微粉鉄鉱石について、これをまず、還元性ガスで還元して予備還元鉱石として低酸化度鉄源原料としてもよい。それは、微粉鉄鉱石もこれを予備還元すると、高酸化物鉄鉱石の酸化鉄成分が還元され、Ｆｅ３Ｏ４やＦｅＯのような低酸化度の鉄鉱石に変化するからである。本発明では、このようにして得られた低酸化度の予備還元鉄鉱石を含む低酸化度鉄源原料と前記微粉鉄鉱石（および粉鉱石）とを混合し、そして造粒した後、その造粒物を焼結機以外の低温（＜８５０℃）プロセスである焼成炉にて焼成して塊成鉱とし、これを直接、高炉用原料にしようとするものである。 In addition, about the said fine powder iron ore, it is good also as a low-reduction degree iron source raw material by reducing this with a reducing gas first as a pre-reduction ore. This is because, when the fine iron ore is also preliminarily reduced, the iron oxide component of the high oxide iron ore is reduced, and the iron ore changes to a low oxidation degree such as Fe 3 O 4 or FeO. In the present invention, the low-oxidized iron source material containing the pre-reduced iron ore with low oxidation degree obtained in this way and the fine iron ore (and fine ore) are mixed and granulated. The granules are baked in a baking furnace which is a low-temperature (<850 ° C.) process other than a sintering machine to form agglomerated minerals, which are directly used as raw materials for a blast furnace.
なお、微粉鉄鉱石を予備還元して低酸化度鉄源原料とする場合、使用する予備還元炉としては、シャフト炉やロータリーキルン、流動層還元炉などの使用が可能である。この予備還元炉内には、還元性ガスを導入して前記微粉鉄鉱石の予備還元処理を行なう。 In addition, when pre-reducing fine iron ore to obtain a low-oxidation iron source material, a shaft furnace, a rotary kiln, a fluidized bed reduction furnace, or the like can be used as a pre-reduction furnace to be used. A reducing gas is introduced into the preliminary reduction furnace to perform a preliminary reduction treatment of the fine iron 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（排ガスのこと）を使用すれば、このガスの顕熱を有効に利用することができるため加熱の必要がなく好ましい。転炉ガスの場合、通常、除塵、冷却して使用されるが、予備還元炉では、このダストも予備還元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。 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 (exhaust gas) is used, the gas will be exposed. Since heat can be used effectively, there is no need for heating, which is preferable. In the case of converter gas, it is usually used after dust removal and cooling. However, in the preliminary reduction furnace, this dust can also be used as a raw material for producing the preliminary reduction ore, so there is no need for dust removal and cooling.
なお、前記微粉鉄鉱石は、還元性雰囲気中で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。従って、予備還元炉の安定した生産のためには、前記予備還元炉では１２００℃未満の温度で還元処理することが好ましい。 When the fine iron ore is heated to 1200 ° C. or higher in a reducing atmosphere, the fine iron ore may partially melt and the particles may be fused. Therefore, for stable production of the prereduction furnace, it is preferable that the prereduction furnace is subjected to reduction treatment at a temperature of less than 1200 ° C.
ところで、転炉ガスや高炉ガスは、ＣＯガス濃度に対してＣＯ２ガス濃度を多く含むものの、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微粉鉄鉱石を予備還元炉で還元すると、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）やウスタイト（ＦｅＯ）にまで還元された予備還元鉱石とすることができる。 Meanwhile, converter gas and blast furnace gas, although rich in CO 2 gas concentration for CO gas concentration, usually, is capable of reducing the extent wustite (FeO). Therefore, when fine iron ore is reduced in a prereduction furnace using a converter gas or a blast furnace gas, metallic iron may be partially included depending on production conditions, but mainly magnetite (Fe 3 O 4 ) or wustite (FeO ) To a pre-reduced ore that has been reduced to
また、本発明において用いる前記低酸化度鉄源原料としては、鉄の酸化度（ＦｅＯｘｏ）で表されるｘｏが０≦ｘｏ≦１．３６の範囲内の粉・粒状物、例えば、ミルスケール、高炉ガスや転炉ＯＧガス中に含まれる各種製鉄ダスト、焼結鉱篩下粉やペレットなどを用いることが好ましい。 In addition, as the low-oxidation iron source material used in the present invention, xo represented by the iron oxidation degree (FeOxo) is a powder / granular material in the range of 0 ≦ xo ≦ 1.36, for example, mill scale, It is preferable to use various iron-making dusts, sintered ore sieve powder, pellets, and the like contained in blast furnace gas and converter OG gas.
前記微粉鉄鉱石、例えば、２５０μｍ以下のコンセントレート、ペレットフィードなどの鉄鉱石、及び６３μｍ以下のペレットフィードや１０μｍ以下のテーリング鉱を３０ｍａｓｓ％以上、好ましくは５０ｍａｓｓ％以上７０ｍａｓｓ％以下含有させる。これらは必要に応じて、前述のように予備還元した低酸化度予備還元鉄鉱石の形態にして用いてよい。なお、シンターフィードと呼ばれる粉鉱石を併用してもよい。 The fine iron ore, for example, an iron ore such as a concentrate of 250 μm or less and a pellet feed, and a pellet feed of 63 μm or less and a tailing ore of 10 μm or less are contained in an amount of 30 mass% or more, preferably 50 mass% or more and 70 mass% or less. If necessary, these may be used in the form of low-oxidation degree prereduced iron ore preliminarily reduced as described above. In addition, you may use together the powder ore called a sinter feed.
所定量の前記微粉鉄鉱石に対し、鉄の酸化ｘｏが０≦ｘｏ≦１．３６の低酸化度鉄源原料、例えば、ミルスケール粉やダスト、焼結篩下粉、ペレット等を７０ｍａｓｓ％未満、好ましくは３０ｍａｓｓ％〜５０ｍａｓｓ％程度を混合する。この低酸化度鉄源原料の上記所定量を混合する理由は、後述する低温焼成処理を可能にするために、必要な酸化発熱が得られるようにするために必要な量である。 Less than 70 mass% of low-oxidized iron source raw material with iron oxide xo of 0 ≦ xo ≦ 1.36, for example, mill scale powder and dust, sintered sieve powder, pellets, etc., with respect to a predetermined amount of the fine iron ore Preferably, about 30 mass% to about 50 mass% are mixed. The reason why the predetermined amount of the low-oxidation iron source material is mixed is an amount necessary to obtain a necessary oxidation heat generation in order to enable a low-temperature firing process described later.
従って、前記微粉鉄鉱石は、必ずしも低酸化度のものでなくてもよく、少なくとも３０ｍａｓｓ％程度の前記低酸化度鉄源原料さえ混合していればよい。もちろん、予備還元した微粉鉄鉱石を使用することは望ましいがコスト的に不利な場合があり、未予備還元微粉鉄鉱石を使用すること、そして、この微粉鉄鉱石を用いて、直接、高炉原料用塊成鉱を製造することの意義は大きい。 Therefore, the fine iron ore does not necessarily have a low oxidation degree, and it is sufficient that at least about 30 mass% of the low oxidation iron source material is mixed. Of course, it is desirable to use pre-reduced fine iron ore, but it may be costly, use unpre-reduced fine iron ore, and use this fine iron ore directly for blast furnace raw materials. The significance of producing agglomerates is significant.
（２）低温焼成処理
次に、前記微粉鉄鉱石ないしは予備還元炉で還元した予備還元鉱石と、ミルスケールや製鉄ダスト、焼結篩下粉（回収粉）、ペレットなどからなる鉄の酸化度（ｘｏ）が０≦ｘｏ≦１．３６の低酸化度鉄源原料とを、さらに必要に応じて、シンターフィードや副原料、凝結材（コークス、バインダーなど）と共に混合した混合原料とする。そして、この混合原料をパンペレタイザーやドラムミキサー等に供給して造粒する。その後、その造粒物をロータリーキルン等の酸化焼成設備にて２５０℃以上８５０℃以下の温度で酸化焼成して塊成鉱とする。
(2) Low-temperature firing treatment Next, the degree of oxidation of iron comprising the fine iron ore or the pre-reduced ore reduced in the pre-reduction furnace, and mill scale, iron-making dust, sintered sieve powder (collected powder), pellets, etc. xo) is a mixed raw material in which a low-oxidation iron source raw material having 0 ≦ xo ≦ 1.36 is further mixed with a sinter feed, an auxiliary raw material, and a coagulating material (coke, binder, etc.) as necessary. Then, this mixed raw material is supplied to a pan pelletizer, a drum mixer or the like and granulated. Thereafter, the granulated product is oxidized and fired at a temperature of 250 ° C. or higher and 850 ° C. or lower in an oxidation baking facility such as a rotary kiln to obtain agglomerated ore.
このようして得られた塊成鉱は、次に、必要に応じて篩分けして平均粒径が５〜３０ｍｍの大きさの篩上のもの（高炉原料として適した粒径のもの）を高炉用塊成鉱として回収する。一方、その篩下のものは篩下粉として分別して回収する。この篩下粉は、配合原料の一部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 ore thus obtained is then sieved as necessary, and the one on a sieve having an average particle size of 5 to 30 mm (with a particle size suitable as a blast furnace raw material). Recovered as blast furnace agglomerate. On the other hand, the sieving material is separated and collected as sieving powder. This under sieve powder may be used as a part of the blended raw material, or may be used by mixing with the sintered ore under sieve powder during the production of the sintered ore.
このように、本発明では、まず、予備還元したものを含む微粉鉄鉱石と低酸化度鉄源原料からなる配合原料（混合粉）を造粒し、その後、ロータリーキルン等の低温焼成設備内に装入して加熱焼成し、塊成鉱とする。このような処理において、前記配合原料の混合造粒物は、該焼成設備内では酸化性の高温ガス雰囲気に曝されるので酸化され、自身が発熱する。この発熱により、配合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って、塊成化する。 As described above, in the present invention, first, a blended raw material (mixed powder) composed of finely divided iron ore including a pre-reduced material and a low-oxidized iron source material is granulated, and then placed in a low-temperature firing facility such as a rotary kiln. And heat-fired to form agglomerated ore. In such a treatment, the mixed granulated material of the blended raw material is oxidized in the baking facility because it is exposed to an oxidizing high-temperature gas atmosphere, and generates heat. Due to this heat generation, the temperature of the blended raw material particles itself is increased, and the particles are appropriately bonded together and agglomerated.
この点、従来の焼結プロセスの処理では、一般的な配合原料粒子を装入して形成される原料層内の温度を１２００℃以上に保持して焼結反応を進行させることが必要である。一方、本発明では、低酸化度造粒粒子自身の酸化発熱により、粒子温度が自発的に高くなるため、雰囲気温度は８５０℃以下と低い温度であっても反応が十分に進行するようになる。 In this regard, in the conventional sintering process, it is necessary to advance the sintering reaction while maintaining the temperature in the raw material layer formed by charging general raw material particles at 1200 ° C. or higher. . On the other hand, in the present invention, since the particle temperature is spontaneously increased due to the oxidation heat generation of the low oxidation degree granulated particles themselves, the reaction proceeds sufficiently even if the ambient temperature is as low as 850 ° C. or less. .
これに対し、もし、低酸化度（０≦ｘｏ≦０．５）の鉄源原料を多く含む造粒物を焼成するとき、この焼成時の雰囲気温度を９００℃と高くすると、図２（ａ）、（ｂ）に示すように、酸化反応が却って速く進行しすぎて、粒子（塊成鉱）表面に緻密なシェルを形成するようになる。その結果、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、前記焼成炉による酸化焼成処理は、８５０℃以下の温度、好ましくは２５０〜８００℃の温度で行なうことが望ましい。 On the other hand, if a granulated product containing a large amount of iron source material with a low oxidation degree (0 ≦ xo ≦ 0.5) is fired, if the ambient temperature during firing is increased to 900 ° C., FIG. ) And (b), the oxidation reaction proceeds too fast, and a dense shell is formed on the surface of the particles (agglomerated ore). As a result, oxygen does not diffuse into the particles, and the agglomeration reaction does not proceed sufficiently. Therefore, in the present invention, it is desirable that the oxidation baking treatment in the baking furnace is performed at a temperature of 850 ° C. or lower, preferably 250 to 800 ° C.
このように、微粉鉄鉱石に対し、鉄の酸化度ｘｏが０〜１．３６を示す低酸化度鉄源原料を混合して造粒し、その後、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、微粉鉄鉱石に対し酸化度ｘｏが０〜１．３６の低酸化度鉄源原料を混合する利点は、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、該造粒物中の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。従来の焼結プロセスの処理では、焼結原料層内温度を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。 In this way, the fine iron ore is mixed and granulated with a low oxidation iron source material having an iron oxidation degree xo of 0 to 1.36, and then charged into a firing facility such as a rotary kiln. The agglomerated ore is heated, but in this treatment, the advantage of mixing the low-oxidation degree iron source raw material having an oxidation degree xo of 0 to 1.36 with the fine iron ore is that the oxidizing high-temperature gas is used in the firing facility. Since it is exposed to the atmosphere, Fe 3 O 4 and FeO in the granulated product are oxidized and generate heat themselves. Due to this heat generation, the temperature of the raw material particles themselves increases, and the particles are appropriately bonded and agglomerated. In the conventional sintering process, the sintering reaction proceeds by maintaining the internal temperature of the sintering raw material layer at 1200 ° C. or higher. However, in the present invention, the spontaneous oxidation occurs due to the oxidation heat generation of the low-oxidation iron source raw material particles themselves. 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、低酸化度鉄源原料については、酸化度が小さいほど、焼成（酸化）時の単位質量当たりの発熱量が大きいので、その使用量が一定の場合、低酸化度鉄源原料の酸化度が小さ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。 As for the low oxidation iron source material, the lower the oxidation degree, the greater the calorific value per unit mass during firing (oxidation). Therefore, when the amount used is constant, the oxidation degree of the low oxidation iron source material It can be said that the smaller the value is, the better the oxidation reaction proceeds.
以上の説明から明らかなように、微粉鉄鉱石を焼結原料として使用することに代えて、前述したような方法で塊成化した場合、高炉での原料使用量一定とすれば、焼結機での微粉鉄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、原料の平均粒径が大きくなり、焼結ベッドの通気性が改善する。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 is clear from the above explanation, when using the fine iron ore as a sintering raw material and agglomerating by the above-described method, if the raw material usage in the blast furnace is constant, the sintering machine It becomes possible to reduce the use ratio of fine iron ore in As a result, in the sintering machine operation, the average particle size of the raw material is increased, and the air permeability of the sintered bed is improved. 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.
（１）この実施例では、表１に示すような粒径が２５０μｍ以下の微粉鉄鉱石Ａ、粒径が６３μｍ以下のペレットフィードである微粉鉄鉱石Ｂ：２．１０ｋｇに対し、ミルスケールＣを３０ｍａｓｓ％以下、転炉ダストＤを２３．３ｍａｓｓ％以下、予備還元鉱石Ｅを８５ｍａｓｓ％以下、ＲＨＦ発生粉２０ｍａｓｓ％以下混合した。なお、予備還元鉱石Ｅは、上記微粉鉄鉱石の一部を流動層に供給し、還元ガスとして９００℃の高炉ガスを２．５１Ｎｍ３使用して得られたものである。
(1) In this example, mill scale C is used for pulverized iron ore A having a particle size of 250 μm or less as shown in Table 1 and pulverized iron ore B having a particle size of 63 μm or less: 2.10 kg. 30 mass% or less, converter dust D was mixed 23.3 mass% or less, pre-reduced ore E 85 mass% or less, and RHF generated
（２）次に、混合粉重量当たりの発熱量が一定になるように、微粉鉄鉱石（Ａ）、（Ｂ）、低酸化度の予備還元鉱石、ミルスケール、転炉ＯＧダスト、ＲＨＦ発生粉と粉コークスとを表２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下の酸化性雰囲気中、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。微粉鉄鉱石Ａのみを用いた例では、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、低酸化度の予備還元鉱石、ミルスケールや転炉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２に示すとおり、低酸化度鉄源原料の平均酸化度（ｘｏ）が小さい方が塊成鉱の強度が高くなっていた。 (2) Next, fine iron ore (A), (B), low-oxidation pre-reduced ore, mill scale, converter OG dust, RHF generated powder so that the calorific value per mixed powder weight is constant. And powder coke as shown in Table 2 (1 to 5), pellets having a size of 10 to 15 mm are prepared with a pelletizer, and the atmosphere is oxidized in an oxidizing atmosphere in an electric furnace. Low temperature firing was performed at a temperature of 500 ° C. for 30 minutes. The strength of the agglomerate obtained at this time is shown in the same table. In the example using only fine iron ore A, at this temperature (500 ° C.), although coke was added, it was not fired and no agglomerate was obtained. On the other hand, in the examples in which the pre-reduced ore having a low oxidation degree, mill scale and converter OG dust were blended, high strength agglomerated ore was obtained for each sample even by low-temperature firing. In addition, as shown in Table 2, the strength of the agglomerate was higher when the average oxidation degree (xo) of the low-oxidation degree iron source material was smaller.
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源原料（ミルスケールや転炉ＯＧダスト）が結合している様子はないが、焼成後にはこれらの原料どうしが結合している様子がわかる。 Next, regarding the example of formulation example (3), cross-sectional photographs of pellets before and after firing are shown in FIG. Before firing, low-oxidation ore and other low-oxidation iron source materials (mill scale and converter OG dust) do not appear to be bound, but after firing, these materials are bound to each other. Recognize.
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、微粉鉄鉱石と低酸化度鉄源原料との混合造粒物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 mixed granulated product of fine iron ore and the low-oxidized iron source material 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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| JPS50130616A (en) * | 1974-04-01 | 1975-10-16 | ||
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| JPS5370907A (en) * | 1976-12-06 | 1978-06-23 | Kobe Steel Ltd | Preparation of pellets of iron ores |
| JPS589939A (en) * | 1981-04-16 | 1983-01-20 | ビ−オ−シ−・リミテツド | Method and plant for baking green pellet of metal ore |
| JPH0649548A (en) * | 1992-07-31 | 1994-02-22 | Kobe Steel Ltd | Production of pellet having high strength of preheated pellet |
| JP2010163656A (en) * | 2009-01-15 | 2010-07-29 | Kobe Steel Ltd | Method for producing iron-ore pellet |
| JP2011225926A (en) * | 2010-04-19 | 2011-11-10 | Jfe Steel Corp | Agglomerated ore including carbonaceous material for iron-making, and producing method therefor |
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| JPS50130616A (en) * | 1974-04-01 | 1975-10-16 | ||
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| JPS5370907A (en) * | 1976-12-06 | 1978-06-23 | Kobe Steel Ltd | Preparation of pellets of iron ores |
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