JP5950098B2 - Method for producing sintered ore - Google Patents
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- JP5950098B2 JP5950098B2 JP2012119569A JP2012119569A JP5950098B2 JP 5950098 B2 JP5950098 B2 JP 5950098B2 JP 2012119569 A JP2012119569 A JP 2012119569A JP 2012119569 A JP2012119569 A JP 2012119569A JP 5950098 B2 JP5950098 B2 JP 5950098B2
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本発明は、高炉に主要鉄源として装入する焼結鉱の製造方法に関し、具体的には、上記焼結鉱を製造する際の焼結原料の一部として製鋼スラグ（転炉スラグ）を用いる焼結鉱の製造方法に関するものである。 The present invention relates to a method for producing sintered ore charged into a blast furnace as a main iron source. Specifically, steelmaking slag (converter slag) is used as a part of a sintering raw material when producing the sintered ore. The present invention relates to a method for producing sintered ore to be used.
高炉製鉄法において主要な鉄源となる焼結鉱は、一般に、次のような工程で製造されている。先ず、主原料となる約１０ｍｍ以下の粉鉱石に、返鉱、フラックスとしての、石灰石、ドロマイト、製鋼スラグなどのＣａＯ系副原料と、珪石、蛇紋岩などのＳｉＯ２系副原料、および、固体燃料（炭材）としての粉コークス等を均一に混合して造粒原料とし、これに適量の水を加えて造粒して擬似粒化である造粒粒子とする。 Sinter ore, which is a major iron source in the blast furnace ironmaking process, is generally manufactured by the following process. First, about 10 mm or less of fine ore as a main raw material, as a return or flux, CaO-based auxiliary materials such as limestone, dolomite, and steelmaking slag, SiO 2- based auxiliary materials such as silica and serpentine, and solid Powdered coke as a fuel (charcoal material) or the like is uniformly mixed to obtain a granulated raw material, and an appropriate amount of water is added thereto to granulate to obtain a granulated particle that is pseudo-granulated.
次いで、上記造粒粒子を焼結原料としてグレート式の焼結機のパレット上に充填して焼結原料層（装入層）を形成した後、上記装入層の表層部中に含まれるコークスに点火し、パレット下方に配設されたウインドボックスで空気を吸引して装入層内に酸素を供給しながらコークスを燃焼させ、その燃焼熱で焼結原料を１２００〜１３８０℃の温度に加熱し、溶融して焼結反応を起こさせ、得られた焼結ケーキを焼結機の出側でクラッシャー等で粉砕し、例えば５ｍｍ篩でスクリーニングし、＋５ｍｍは成品として高炉に送り、−５ｍｍは返鉱として、繰り返し造粒粒子の原料として使用する。 Next, the granulated particles are filled as a sintering raw material on a pallet of a great-type sintering machine to form a sintering raw material layer (charging layer), and then coke contained in the surface layer portion of the charging layer. The coke is burned while sucking air in a wind box arranged below the pallet and supplying oxygen into the charging layer, and the sintering heat is used to heat the sintering raw material to a temperature of 1200 to 1380 ° C. The resulting sintered cake is crushed with a crusher or the like on the exit side of the sintering machine, screened with a 5 mm sieve, for example, +5 mm is sent to the blast furnace as a product, -5 mm is It is used as a raw material for repeated granulated particles as return ore.
このようにして製造した焼結鉱の特性としては、冷間強度、被還元性、還元粉化性などの特性に優れていることが要求される。そして、この品質を確保するため、銘柄によって異なる特性が異なる鉄鉱石の性状に合わせて副原料の配合割合やコークス粉の添加量等を適宜調整している。また、近年、鉄鋼生産量の増加に伴い、焼結鉱の生産量を高めることが求められている。さらに、高炉の生産性を高めるため、より高品質の焼結鉱を製造することも求められている。そのため、近年の焼結機においては、高品質の焼結鉱を生産性よく製造することが課題となっている。 The properties of the sintered ore thus produced are required to be excellent in properties such as cold strength, reducibility, and reduced powderability. And in order to ensure this quality, the mixture ratio of an auxiliary material, the addition amount of coke powder, etc. are adjusted suitably according to the property of the iron ore from which a characteristic which changes with brands differs. In recent years, with the increase in steel production, it has been required to increase the production of sintered ore. Furthermore, in order to increase the productivity of the blast furnace, it is also required to produce a higher quality sintered ore. Therefore, in a recent sintering machine, it has been a problem to produce a high-quality sintered ore with high productivity.
ところで、製鋼工程から発生する製鋼スラグとしては、転炉等の脱炭工程で発生する脱炭スラグ（転炉スラグ）、脱珪工程で発生する脱珪スラグ、脱硫工程で発生する脱硫スラグ、脱燐工程で発生する脱燐スラグ、二次製錬工程で発生する二次製錬スラグおよび連続鋳造工程で発生する連鋳スラグなどがある。なお、脱珪スラグ、脱硫スラグおよび脱燐スラグは、溶銑予備処理スラグと称されることもある。 By the way, steelmaking slag generated from the steelmaking process includes decarburization slag (converter slag) generated in a decarburization process such as a converter, desiliconization slag generated in a desiliconization process, desulfurization slag generated in a desulfurization process, and desulfurization. There are dephosphorization slag generated in the phosphorus process, secondary smelting slag generated in the secondary smelting process, and continuous cast slag generated in the continuous casting process. In addition, desiliconization slag, desulfurization slag, and dephosphorization slag may be called hot metal pretreatment slag.
しかし、上記製鋼スラグは、鉄鋼製造分野では余り有効に再利用されていない。というのは、例えば、脱炭スラグは、脱燐工程でリサイクルされる場合があるが、融点が高いため、脱燐炉において多量にリサイクルすることは難しい。そのため、製鋼スラグは、従来、土木分野を中心に再利用されており、生産量の約４０％が埋立てや廃棄処分されている。しかし、近年、環境規制の強化に伴い、埋立てや廃棄処分される量も徐々に減少してきている。また、セメント原料としても使用されているが、その量はわずかでしかない。 However, the steelmaking slag has not been reused very effectively in the steel manufacturing field. This is because, for example, decarburized slag may be recycled in the dephosphorization process, but because of its high melting point, it is difficult to recycle in a large amount in a dephosphorization furnace. For this reason, steelmaking slag has been reused mainly in the civil engineering field, and about 40% of the production is landfilled or disposed of. However, in recent years, the amount of landfill and disposal has gradually decreased with the strengthening of environmental regulations. It is also used as a raw material for cement, but the amount is very small.
そこで、製鋼スラグにはＣａＯ分が多く含まれていることに着目し、これを焼結鉱の製造プロセスにおいてフラックスとして再利用することが検討されている。例えば、特許文献１には、焼結配合原料に転炉スラグを用いるに際して、ミルスケールを混合することで焼結鉱の品質を向上する技術が、特許文献２には、ゲーサイト成分の多い鉄鉱石に、鉄鉱石との反応性の低い転炉スラグを混合することで、焼結鉱の強度を弱める反応を抑制する技術が開示されている。また、特許文献３には、石灰石と比較して鉄鉱石との反応性に劣る転炉スラグの粒度を細かくして反応面積を大きくし、反応速度を高めることで、フラックスとして使用する技術が開示されている。また、特許文献４には、焼結鉱の品質低下を招く難焼結性のドロマイトを易焼結性の製鋼スラグと選択的に組み合わせることで、焼結鉱の品質低下を防止しつつ効率的に製鋼スラグをリサイクルする技術が開示されている。 Therefore, paying attention to the fact that steelmaking slag contains a large amount of CaO, it has been studied to reuse this as a flux in the manufacturing process of sintered ore. For example, Patent Document 1 discloses a technique for improving the quality of sintered ore by mixing a mill scale when converter slag is used as a sintered blending raw material, and Patent Document 2 discloses iron ore having a large number of goethite components. The technique which suppresses the reaction which weakens the intensity | strength of a sintered ore by mixing the converter slag with low reactivity with an iron ore with a stone is disclosed. In addition, Patent Document 3 discloses a technique for use as a flux by increasing the reaction area by increasing the reaction area by reducing the particle size of the converter slag, which is inferior in reactivity with iron ore compared to limestone. Has been. Further, Patent Document 4 is effective in preventing the deterioration of the quality of the sintered ore by selectively combining the hardly sinterable dolomite that causes the quality reduction of the sintered ore with the easily sinterable steelmaking slag. Discloses a technique for recycling steelmaking slag.
しかしながら、表１に、転炉スラグと脱硫スラグの成分組成例を示したように、製鋼スラグは、その種類によって成分組成や融点が大きく異なり、また、脱硫スラグは、ＣａＯ以外に、多くのＡｌ２Ｏ３を含んでいるのが特徴である。このＡｌ２Ｏ３は、焼結鉱を焼成する際、必要な溶融相の溶融温度を上昇させて流動性を低下するため、焼結鉱の生産性を著しく阻害する。また、転炉スラグは、融点が比較的高いので、脱硫スラグと同様、焼結に必要な溶融相の生成温度を上昇させるという問題がある。そのため、製鋼スラグを焼結原料として再使用することについては、従来、あまり積極的に行われていないのが実情である。 However, as shown in Table 1, component composition examples of converter slag and desulfurization slag, steelmaking slag differs greatly in component composition and melting point depending on the type, and desulfurization slag contains many Al in addition to CaO. It is characterized by containing 2 O 3 . Since this Al 2 O 3 raises the melting temperature of a necessary molten phase and lowers the fluidity when firing the sintered ore, it significantly impedes the productivity of the sintered ore. In addition, since converter slag has a relatively high melting point, there is a problem in that the temperature for forming a molten phase necessary for sintering is increased, similar to desulfurization slag. For this reason, the fact that steelmaking slag is reused as a raw material for sintering has not been actively performed so far.
本発明は、製鋼スラグが有する上記問題点に鑑みてなされたものであり、その目的は、焼結鉱の生産率を低下させることなく、製鋼スラグ、中でも転炉スラグを、焼結原料の一部として積極的に有効活用することができる焼結鉱の製造方法を提案することにある。 The present invention has been made in view of the above-mentioned problems of steelmaking slag, and its purpose is to reduce steelmaking slag, especially converter slag, as a sintered raw material without reducing the production rate of sintered ore. The present invention proposes a method for producing sintered ore that can be effectively used as a part.
発明者らは、上記課題の解決に向けて鋭意検討を重ねた結果、以下のことに想到した。従来、焼結原料（造粒粒子）を製造するに際しては、製鋼スラグを鉄鉱石や石灰石などの主原料と均一に混合することだけを考えていた。しかし、均一に混合した場合には、製鋼スラグの悪影響が焼結原料全体に及んでしまう。そこで、製鋼スラグと、製鋼スラグ以外の原料とを分別して別々に造粒した上で、製鋼スラグ由来の造粒粒子を製鋼スラグ以外の原料由来の造粒粒子中に分散して混合させて焼結機のパレット上に装入してやれば、製鋼スラグによる弊害を製鋼スラグ由来の造粒粒子内に封じ込めることができるので、製鋼スラグ以外の原料由来の造粒粒子にまで悪影響を及ぼすことがないことに想到した。 As a result of intensive studies aimed at solving the above problems, the inventors have come up with the following. Conventionally, when producing a sintered raw material (granulated particles), only steelmaking slag was uniformly mixed with main raw materials such as iron ore and limestone. However, when uniformly mixed, the adverse effect of the steelmaking slag reaches the entire sintered raw material. Therefore, after steelmaking slag and raw materials other than steelmaking slag are separated and granulated separately, the granulated particles derived from steelmaking slag are dispersed and mixed in the granulated particles derived from raw materials other than steelmaking slag and sintered. If it is loaded on the pallet of the kneading machine, the harmful effects of steelmaking slag can be contained in the granulated particles derived from steelmaking slag, so that it does not adversely affect the granulated particles derived from raw materials other than steelmaking slag. I came up with it.
さらに、製鋼スラグの中でも転炉スラグを使用する場合には、造粒原料としての転炉スラグに、融点降下剤として、ＣａＯを主成分とするフラックスあるいはＦｅを主成分とするフラックスを添加することによって、転炉スラグ由来の造粒粒子の溶融温度を転炉スラグ以外の原料由来の造粒粒子と同程度の温度まで低下させることができるので、焼結時に生成する融液量が増加し、周囲の転炉スラグ以外の原料由来の造粒粒子との溶融同化が促進され、焼結組織が改善されること、その結果、転炉スラグを添加した焼結鉱の強度が向上し、成品歩留まりも向上することを見出し、本発明を完成させるに至った。 Furthermore, when converter slag is used among steelmaking slags, flux containing CaO as a main component or flux containing Fe as a main component is added as a melting point depressant to the converter slag as a granulation raw material. By this, the melting temperature of the granulated particles derived from the converter slag can be lowered to the same temperature as the granulated particles derived from the raw materials other than the converter slag, so that the amount of melt generated during sintering increases, Melt assimilation with granulated particles derived from raw materials other than the surrounding converter slag is promoted and the sintered structure is improved. As a result, the strength of the sintered ore added with the converter slag is improved and the product yield is increased. Has been found to improve, and the present invention has been completed.
すなわち、本発明は、主として鉄鉱石、ＣａＯ系副原料、ＳｉＯ２系副原料、返鉱および固体燃料から構成される造粒原料を造粒して造粒粒子とし、これを焼結原料として焼結機のパレット上に装入し、焼結して焼結鉱を製造する方法において、前記焼結原料の一部として転炉スラグを用いる際、転炉スラグと転炉スラグ以外の原料とを分別し、それぞれを別々に造粒して転炉スラグ由来の造粒粒子と転炉スラグ以外の原料由来の造粒粒子とするとともに、前記転炉スラグ由来の造粒粒子を、造粒原料に転炉スラグに対して質量比で１未満の融点降下剤を添加し、かつ、質量平均径が転炉スラグ以外の原料由来の造粒粒子以上となるように造粒した上で、転炉スラグ以外の原料由来の造粒粒子中に分散させてパレット上に装入することを特徴とする焼結鉱の製造方法である。 That is, the present invention granulates a granulated raw material mainly composed of iron ore, CaO-based auxiliary material, SiO 2 -based auxiliary material, return mineral, and solid fuel into granulated particles, which are sintered as a sintered raw material. In a method for producing sintered ore by charging on a pallet of a kneading machine, when using converter slag as part of the sintered raw material, converter slag and raw materials other than converter slag are used. Separately and granulate each separately to obtain granulated particles derived from converter slag and raw materials other than converter slag, and granulated particles derived from converter slag into granulated raw materials. After adding a melting point depressant with a mass ratio of less than 1 to the converter slag and granulating so that the mass average diameter is equal to or greater than the granulated particles derived from raw materials other than the converter slag, the converter slag Dispersed in granulated particles derived from other raw materials and charged on a pallet It is a manufacturing method of sintered ore.
本発明の焼結鉱の製造方法は、上記融点降下剤として、ＣａＯを主成分とするフラックスおよび／またはＦｅを主成分とするフラックスを添加することを特徴とする。 The method for producing sintered ore of the present invention is characterized in that a flux mainly composed of CaO and / or a flux mainly composed of Fe is added as the melting point depressant.
また、本発明の焼結鉱の製造方法は、上記ＣａＯを主成分とするフラックスとして、石灰石、生石灰および脱硫スラグのいずれか１以上を添加することを特徴とする。 Moreover, the manufacturing method of the sintered ore of this invention is characterized by adding any one or more of limestone, quicklime and desulfurized slag as the flux mainly composed of CaO.
また、本発明の焼結鉱の製造方法は、上記Ｆｅを主成分とするフラックスとして、ミルスケール、鉄鉱石および転炉ダストのいずれか１以上を添加することを特徴とする。 Moreover, the manufacturing method of the sintered ore of this invention adds one or more of a mill scale, an iron ore, and converter dust as a flux which has the said Fe as a main component, It is characterized by the above-mentioned.
また、本発明の焼結鉱の製造方法は、上記ＣａＯを主成分とするフラックスを、転炉スラグに対するＣａＯの質量比で０．２５以下の範囲で添加することを特徴とする。 Moreover, the manufacturing method of the sintered ore of this invention is characterized by adding the flux which has the said CaO as a main component in the range of 0.25 or less by the mass ratio of CaO with respect to converter slag.
また、本発明の焼結鉱の製造方法は、上記Ｆｅを主成分とするフラックスを、転炉スラグに対するＦｅの質量比で０．３５以下の範囲で添加することを特徴とする。 Moreover, the manufacturing method of the sintered ore of this invention adds the flux which has the said Fe as a main component in 0.35 or less by the mass ratio of Fe with respect to converter slag.
また、本発明の焼結鉱の製造方法は、上記転炉スラグ由来の造粒粒子の質量平均径を、転炉スラグ以外の原料由来の造粒粒子の１．５倍以上とすることを特徴とする。 The method for producing a sintered ore of the present invention is characterized in that the mass average diameter of the granulated particles derived from the converter slag is 1.5 times or more that of the granulated particles derived from raw materials other than the converter slag. And
本発明によれば、転炉スラグと転炉スラグ以外の造粒原料とを分別してそれぞれを別々に造粒して転炉スラグ由来の造粒粒子と転炉スラグ以外の原料由来の造粒粒子とした後、転炉スラグ由来の造粒粒子を転炉スラグ以外の原料由来の造粒粒子中に分散させて焼結機のパレット上に装入するようにしたので、転炉スラグによる悪影響を転炉スラグ由来の造粒粒子内に封じ込め、他の造粒粒子に及ぼす悪影響を最小限に抑制することができる。 According to the present invention, the converter slag and the granulated raw material other than the converter slag are separated and granulated separately, and the granulated particles derived from the converter slag and the raw materials other than the converter slag are granulated. After that, the granulated particles derived from the converter slag were dispersed in the granulated particles derived from the raw materials other than the converter slag and charged on the pallet of the sintering machine. It can be contained in the granulated particles derived from the converter slag, and adverse effects on other granulated particles can be minimized.
また、本発明によれば、転炉スラグ由来の造粒粒子を、転炉スラグ以外の原料由来の造粒粒子以上の粒子径とするので、焼結時の通気性を妨げることなく焼結操業を行うことが可能となる。さらに、本発明によれば、転炉スラグに融点降下剤を添加し、転炉スラグ由来の造粒粒子の融点を低下させるので、焼結時における融液の発生量が増大し、転炉スラグ由来の造粒粒子と他の造粒粒子との溶融同化が促進されるので、焼結鉱の強度を向上することができる。 Further, according to the present invention, the granulated particles derived from the converter slag are made larger than the granulated particles derived from the raw materials other than the converter slag, so that the sintering operation can be performed without impeding the air permeability during the sintering. Can be performed. Furthermore, according to the present invention, since a melting point depressant is added to the converter slag and the melting point of the granulated particles derived from the converter slag is lowered, the amount of melt generated during sintering is increased, and the converter slag is increased. Since melt assimilation between the derived granulated particles and other granulated particles is promoted, the strength of the sintered ore can be improved.
したがって、本発明によれば、焼結機の生産性を害することなく、転炉スラグを焼結原料の一部として積極的に再利用することが可能となるので、製鋼スラグのリサイクル率の向上に大きく寄与する。 Therefore, according to the present invention, the converter slag can be actively reused as a part of the sintering raw material without impairing the productivity of the sintering machine, and thus the steelmaking slag recycling rate is improved. Greatly contributes.
発明者らは、転炉スラグを焼結原料として積極的に活用する方策について鋭意検討を重ねた。その結果、従来、転炉スラグを焼結原料の一部として用いる際、鉄鉱石や石灰石などの原料と均一に混合した後、造粒粒子としていた。そこで、従来とは発想を転換し、転炉スラグを、転炉スラグ以外の原料と分別して造粒し、その他の原料由来の造粒粒子中に、転炉スラグ由来の造粒粒子を均一かつ離間させた状態にして（分散させて）、焼結機のパレットに装入してやれば、転炉スラグの弊害を転炉スラグ由来の造粒粒子内に封じ込めることができるのではないかと考えた。すなわち、従来は、転炉スラグを他の造粒原料と均一に混合していたため、焼結原料全体に転炉スラグの弊害が及んでいたが、転炉スラグを、他の原料とは分別して別々に造粒し、他の原料から得られる造粒粒子から分離してやれば、転炉スラグの弊害はその造粒粒子内にとどまり、他の造粒粒子に悪影響を及ぼすことがなくなるのではないかと考えた。 Inventors repeated earnest examination about the policy of utilizing converter slag positively as a sintering raw material. As a result, conventionally, when converter slag is used as a part of the sintering raw material, it is granulated particles after uniformly mixing with raw materials such as iron ore and limestone. Therefore, the conventional idea is changed, and the converter slag is granulated separately from raw materials other than the converter slag, and the granulated particles derived from the converter slag are uniformly and granulated in the granulated particles derived from other raw materials. It was thought that if they were separated (dispersed) and charged into the pallet of the sintering machine, the harmful effects of the converter slag could be contained in the granulated particles derived from the converter slag. In other words, conventionally, converter slag was uniformly mixed with other granulated raw materials, so the negative effect of converter slag was exerted on the entire sintered raw material, but the converter slag was separated from other raw materials. If granulated separately and separated from the granulated particles obtained from other raw materials, the harmful effects of converter slag will remain in the granulated particles, and it will not adversely affect other granulated particles. Thought.
また、転炉スラグの融点は、前述したように比較的高温であり、焼結時に発生する融液の生成量が少ないため、焼結組織が脆弱となり、転炉スラグ由来の造粒粒子が存在する部分が、焼結鉱の破壊の起点となるおそれがある。そこで、転炉スラグに、例えば、ＣａＯを主成分とする石灰石等やＦｅを主成分とするミルスケールや鉄鉱石等の融点降下剤を添加し、転炉スラグ由来の造粒粒子の融点を低下してやれば、焼結時に生成する融液が増大して、周囲の造粒粒子との溶融同化が促進されるので、焼結鉱の強度を高めることができるのではないかと考えた。 In addition, the melting point of converter slag is relatively high as described above, and since the amount of melt generated during sintering is small, the sintered structure becomes brittle and granulated particles derived from converter slag exist. There is a possibility that the part to be the starting point of the destruction of the sintered ore. Therefore, melting point depressants such as limestone containing CaO as the main component, mill scale and iron ore containing Fe as the main component are added to the converter slag to lower the melting point of the granulated particles derived from the converter slag. Then, since the melt produced | generated at the time of sintering increases and fusion assimilation with the surrounding granulated particle is accelerated | stimulated, I thought that the intensity | strength of a sintered ore could be raised.
そこで、発明者らは、配合条件を表２に示したＴ１〜４のように４水準に変えた造粒原料を準備し、以下の方法で造粒粒子とした後、焼結試験鍋を用いた焼結実験を行った。なお、本実験では、転炉スラグとして、表１に示した比較的低融点の転炉スラグＡを０．５ｍｍ以下に粉砕したものを用いた。
・Ｔ１：図１に示したように、転炉スラグ以外の原料をミキサーに投入して均一に混合し、適量の水を添加した後、ドラムミキサーで造粒粒子とした。得られた造粒粒子の粒子径は、質量平均で３．３ｍｍ、調和平均で１．１０ｍｍであった。
・Ｔ２：Ｔ１と同様、転炉スラグと転炉スラグ以外の原料のすべての原料をミキサーに投入して均一に混合し、適量の水を添加した後、ドラムミキサーで造粒粒子とした。得られた造粒粒子の粒子径は、質量平均径で３．２ｍｍ、調和平均で０．９０ｍｍであった。
・Ｔ３：図２に示しように、転炉スラグ以外の原料は、ミキサーおよびドラムミキサーを用いて、質量平均径で３．３ｍｍの大きさの造粒粒子とし、また、転炉スラグは、１ｍｍ以下に粉砕した後、ペレタイザを用いて質量平均径で３．３ｍｍの造粒粒子とした。次いで、上記転炉スラグ以外の原料由来の造粒粒子と転炉スラグ由来の２種類の造粒粒子を混合した。混合後の粒子の調和平均径は１．１０ｍｍであった。
・Ｔ４：転炉スラグ以外の原料は、Ｔ３同様に造粒し、転炉スラグは、１ｍｍ以下に粉砕した後、ペレタイザを用いて質量平均径で６．７ｍｍの造粒粒子とした。次いで、２種類の造粒粒子を混合した。混合後の粒子の調和平均径は１．２０ｍｍであった。
Therefore, the inventors prepared a granulated raw material whose blending conditions were changed to 4 levels as shown in T1 to T4 shown in Table 2, and made granulated particles by the following method, and then used a sintering test pot. Sintering experiments were performed. In this experiment, the converter slag obtained by pulverizing the converter slag A having a relatively low melting point shown in Table 1 to 0.5 mm or less was used.
-T1: As shown in FIG. 1, raw materials other than the converter slag were put into a mixer and mixed uniformly, and after adding an appropriate amount of water, granulated particles were formed with a drum mixer. The resulting granulated particles had a mass average of 3.3 mm and a harmonic average of 1.10 mm.
-T2: As with T1, all the raw materials other than the converter slag and the converter slag were put into a mixer and mixed uniformly, and after adding an appropriate amount of water, granulated particles were formed with a drum mixer. The obtained granulated particles had a mass average particle diameter of 3.2 mm and a harmonic average of 0.90 mm.
・ T3: As shown in FIG. 2, the raw materials other than the converter slag are granulated particles having a mass average diameter of 3.3 mm using a mixer and a drum mixer, and the converter slag is 1 mm. After pulverizing below, granulated particles having a mass average diameter of 3.3 mm were obtained using a pelletizer. Next, granulated particles derived from raw materials other than the converter slag and two types of granulated particles derived from the converter slag were mixed. The harmonic average diameter of the particles after mixing was 1.10 mm.
-T4: Raw materials other than converter slag were granulated in the same manner as T3, and the converter slag was pulverized to 1 mm or less, and then granulated particles having a mass average diameter of 6.7 mm using a pelletizer. Next, two types of granulated particles were mixed. The harmonic average diameter of the particles after mixing was 1.20 mm.
ここで、転炉スラグを含む全ての造粒原料を均一に混合して造粒したＴ２の造粒後の調和平均径が、転炉スラグを含まない造粒原料を造粒したＴ１よりも小さくなっている理由は、転炉スラグが造粒性を阻害しているためと考えられる。また、転炉スラグとその他の原料を分別して別々に造粒した後、それらを配合したＴ３，Ｔ４において配合後の調和平均径を大きくできた理由は、転炉スラグ以外の原料由来の造粒粒子の粒子径はＴ１と同じであるが、転炉スラグ由来の造粒粒子を造粒性に優れるペレタイザを用いて、質量平均径が転炉スラグ以外の原料由来の造粒粒子以上となるように造粒したためである。 Here, the harmonic average diameter after granulation of T2 obtained by uniformly mixing and granulating all the granulated raw materials including converter slag is smaller than T1 obtained by granulating the granulated raw material not including converter slag. The reason is that the converter slag hinders granulation. Moreover, after separating and granulating the converter slag and other raw materials separately, the reason why the harmonic average diameter after blending was increased in T3 and T4 blended with them was granulated from raw materials other than the converter slag The particle diameter of the particles is the same as that of T1, but using a pelletizer excellent in granulating properties of the granulated particles derived from the converter slag, the mass average diameter is equal to or larger than the granulated particles derived from raw materials other than the converter slag. Because it was granulated.
次いで、上記のようにして得たＴ１〜Ｔ４の造粒粒子を焼結原料として、焼結実験を行った。焼結実験は、内径が２９０ｍｍφ、高さが４００ｍｍの焼結試験鍋を用い、Ｔ１およびＴ２の造粒粒子は、造粒粒子をそのまま焼結原料として試験鍋に充填し、一方、Ｔ３およびＴ４の造粒粒子は、図３に示したように、転炉スラグ由来の造粒粒子が、転炉スラグ以外の原料由来の造粒粒子中に分散するように混合して試験鍋に充填した後、充填層の最表面に点火し、試験鍋の下方からブロアを用いて一定圧力で吸引して空気を充填層内に導入し、焼結原料中の粉コークスを燃焼させることにより行った。なお、上記焼結実験においては、焼結開始から終了するまでの所要時間、焼結中に試験鍋内を通過する平均の空気量（風量）および得られた焼結鉱の強度を測定し、それらの結果から、焼結鉱の生産率を求めた。 Next, a sintering experiment was performed using T1-T4 granulated particles obtained as described above as a sintering raw material. In the sintering experiment, a sintering test pan having an inner diameter of 290 mmφ and a height of 400 mm was used, and the granulated particles of T1 and T2 were filled into the test pan as a raw material for the granulation, while T3 and T4 As shown in FIG. 3, after the granulated particles derived from the converter slag are mixed and dispersed in the granulated particles derived from the raw materials other than the converter slag, as shown in FIG. Then, the outermost surface of the packed bed was ignited, sucked at a constant pressure using a blower from below the test pan, air was introduced into the packed bed, and the powder coke in the sintered raw material was burned. In the above sintering experiment, the time required from the start to the end of sintering, the average amount of air passing through the test pan during sintering (air volume) and the strength of the obtained sintered ore were measured, From these results, the production rate of sintered ore was obtained.
図４に、上記焼結実験結果について、焼結原料（造粒粒子）の調和平均径と併せて示した。図４について、転炉スラグを含まない原料のみを用いたＴ１をベースとして他の条件を対比してみると、転炉スラグを均一に混合した造粒粒子の調和平均径が小さいＴ２では、焼結時の平均風量、焼結鉱の冷間強度が低下し、生産率も大きく減少している。
これに対して、転炉スラグ由来の原料と、転炉スラグ以外の原料とを分別して造粒し、転炉スラグ由来の造粒粒子が転炉スラグ以外の原料由来の造粒粒子中に分散するように混合し、かつ、混合後の調和平均径をＴ１と同じ１．１０ｍｍとしたＴ３では、焼結時の平均風量、焼結鉱の冷間強度、生産率とも若干の低下するものの、Ｔ２ほど大きな低下は認められない。
さらに、混合後の調和平均径をＴ３より大きい１．２０ｍｍとしたＴ４の場合には、転炉スラグ用いているにもかかわらず、焼結時の平均風量、焼結鉱の冷間強度、生産率のいずれもＴ１を超えており、焼結原料として転炉スラグを活用することに成功している。
本発明は、上記の新規知見に、さらに検討を加えて完成したものである。
FIG. 4 shows the result of the sintering experiment together with the harmonic mean diameter of the sintered raw material (granulated particles). When comparing the other conditions with reference to T1 using only the raw material not containing converter slag in FIG. 4, in T2, where the harmonic average diameter of the granulated particles uniformly mixed with converter slag is small, The average air volume at the time of sintering and the cold strength of the sintered ore have been reduced, and the production rate has been greatly reduced.
On the other hand, the raw material derived from the converter slag and the raw material other than the converter slag are separated and granulated, and the granulated particles derived from the converter slag are dispersed in the granulated particles derived from the raw material other than the converter slag. In T3, the harmonic average diameter after mixing was 1.10 mm, the same as T1, but the average air volume during sintering, the cold strength of the sintered ore, and the production rate slightly decreased, There is no significant decrease as much as T2.
Furthermore, in the case of T4 where the harmonic mean diameter after mixing is 1.20 mm, which is larger than T3, the average air volume during sintering, the cold strength of sintered ore, All of the rates exceeded T1, and the converter slag was successfully used as a sintering raw material.
The present invention has been completed by further studying the above-described novel findings.
上記のように、本発明は、鉄鉱石、ＣａＯ系副原料、ＳｉＯ２系副原料、返鉱および固体燃料（粉コークス等の炭材）から主として構成される造粒原料を混合し、適量の水を添加し、均一に混合した後、造粒して擬似粒子である造粒粒子とし、これを焼結原料としてパレット上に充填して焼結原料層（装入層）を形成し、その後、上記焼結原料層中の固体燃料（コークス等）に点火し、パレット下方に配設されたウインドボックスで空気を装入層内に導入し、焼結原料を燃焼・溶融させて焼結鉱を製造する方法である点において、従来技術との違いはない。 As described above, the present invention mixes a granulated raw material mainly composed of iron ore, CaO-based auxiliary material, SiO 2 -based auxiliary material, return ore and solid fuel (carbon material such as powdered coke), and adds an appropriate amount. After adding water and mixing uniformly, it is granulated into granulated particles that are pseudo particles, and this is filled on a pallet as a sintering raw material to form a sintering raw material layer (charging layer), and then The solid fuel (coke etc.) in the sintered raw material layer is ignited, air is introduced into the charging layer by a wind box disposed below the pallet, and the sintered raw material is burned and melted to sinter the ore. There is no difference from the prior art in that it is a method of manufacturing.
しかし、本発明は、上記焼結原料の一部として転炉スラグを用いるに際しては、従来技術のように転炉スラグを他の造粒原料と均一に混合するのではなく、転炉スラグと転炉スラグ以外の原料とを分別し、それぞれを別々に造粒するとともに、転炉スラグ由来の造粒粒子を、転炉スラグ以外の原料由来の造粒粒子中に分散させて焼結機のパレット上に装入し、焼結することによって、転炉スラグによる弊害を転炉スラグ由来の造粒粒子内に封じ込め、他の原料由来の造粒粒子に上記弊害が及ぶのを防止するようにしたところに第一の特徴がある。 However, according to the present invention, when converter slag is used as a part of the sintered raw material, the converter slag is not mixed uniformly with other granulated raw materials as in the prior art, but the converter slag and the converter are not mixed. The raw material other than the furnace slag is separated and granulated separately, and the granulated particles derived from the converter slag are dispersed in the granulated particles derived from the raw material other than the converter slag, and the pallet of the sintering machine By charging and sintering, the harmful effects of converter slag are contained in the granulated particles derived from the converter slag, and the above harmful effects are prevented from affecting the granulated particles derived from other raw materials. There is a first feature.
さらに、上記封じ込めの効果をより高めるためには、転炉スラグ由来の造粒粒子の粒子径（質量平均径）を転炉スラグ以外の原料由来の造粒粒子以上となるように造粒してやることが必要であり、好ましくは１．５倍以上、より好ましくは２倍以上とするのが望ましい。これによって、転炉スラグ由来の造粒粒子数（存在箇所）を低減できるので、転炉スラグ由来の造粒粒子が、転炉スラグ以外の原料由来の造粒粒子に及ぼす悪影響を最小限に留めることができる。さらに、造粒粒子径を大きくすることは、焼結時における通気性を改善され、焼結時間が短縮されることにもなるので、生産率の向上にも寄与する。その結果、上記効果がより顕著となり、転炉スラグを焼結原料として有効活用することが可能となる。 Furthermore, in order to further enhance the containment effect, granulation is performed so that the particle diameter (mass average diameter) of the granulated particles derived from the converter slag is equal to or larger than the granulated particles derived from raw materials other than the converter slag. Is preferably 1.5 times or more, more preferably 2 times or more. As a result, the number of granulated particles derived from the converter slag (existing locations) can be reduced, so that the adverse effect of the granulated particles derived from the converter slag on the granulated particles derived from raw materials other than the converter slag is minimized. be able to. Furthermore, increasing the granulated particle diameter improves air permeability during sintering and shortens the sintering time, thereby contributing to an improvement in production rate. As a result, the above effect becomes more prominent and the converter slag can be effectively used as a sintering raw material.
なお、転炉スラグ由来の造粒粒子を大きくするための造粒装置として、パンペレタイザの他、アイリッヒミキサー、例えば、ペレガイア（（株）北川鉄工所製））等の混合強化型の造粒装置を好ましく用いることができる。ただし、これらの造粒装置は、処理能力が比較的小さいので、転炉スラグ由来の造粒粒子の造粒のみに適用するのが好ましい。したがって、造粒能力に優れるものであれば、他の設備を用いてもよい。 As granulators for enlarging granulated particles derived from converter slag, in addition to pan pelletizers, Eirich mixers such as Pelegaia (manufactured by Kitagawa Iron Works Co., Ltd.), etc. are mixed and strengthened granulators. Can be preferably used. However, since these granulators have a relatively small processing capacity, it is preferable to apply only to granulation of granulated particles derived from converter slag. Therefore, other equipment may be used as long as it has excellent granulation ability.
ところで、転炉スラグを焼結原料の一部として使用する場合には、前述したように、転炉スラグ単体の融点が比較的高温であることに起因して、転炉スラグ由来の造粒粒子部分が焼結鉱の破壊の起点となるおそれがある。
そこで、上記問題点を回避するため、造粒原料となる転炉スラグに対して、融点降下剤を適量添加し、転炉スラグ由来の造粒粒子の融点を低下させるところに、本発明の第二の特徴がある。すなわち、融点降下剤の添加によって、焼結時に生成する融液の量が増大し、転炉スラグ由来の造粒粒子と、周囲の転炉スラグ以外の原料由来の造粒粒子との溶融同化が促進されるため、焼結鉱全体としての組織が改善されて、焼結鉱の強度を高めることができ、ひいては、焼結鉱の歩留向上や焼結機の生産性向上を達成することができる。上記融点降下剤の添加は、表１に示した転炉スラグＢやＣのような、融点が比較的高温であるがために従来あまり再利用されていなかった転炉スラグに対して特に有効である。
By the way, when the converter slag is used as a part of the sintering raw material, the granulated particles derived from the converter slag are caused by the relatively high melting point of the converter slag as described above. There is a possibility that the portion may become a starting point of destruction of the sintered ore.
Therefore, in order to avoid the above problems, an appropriate amount of a melting point depressant is added to the converter slag as the granulation raw material to lower the melting point of the granulated particles derived from the converter slag. There are two characteristics. That is, the addition of a melting point depressant increases the amount of melt produced during sintering, and melt assimilation of granulated particles derived from converter slag and granulated particles derived from raw materials other than the surrounding converter slag As a result, the structure of the sintered ore as a whole can be improved, and the strength of the sintered ore can be increased. Consequently, the yield of the sintered ore can be improved and the productivity of the sintering machine can be improved. it can. The addition of the melting point depressant is particularly effective for the converter slag that has not been reused so much because of its relatively high melting point, such as the converter slag B and C shown in Table 1. is there.
上記融点降下剤の融点を下げる効果は、少量の添加でも発現する。しかし、多量の添加は、融点を下げる効果は十分に得られるものの、転炉スラグ由来の造粒粒子の量が増加し、既存のペレタイザ等の造粒設備では処理能力が小さいため、新たな造粒設備が必要となり、設備コストの上昇につながるおそれがある。したがって、本発明では転炉スラグに添加する融点降下剤は、転炉スラグに対する質量比で１未満とする。なお、融点降下の効果は０超えであれば得られるが、確実に融点を下げるためには、転炉スラグに対する質量比で０．２０以上添加するのが好ましい。 The effect of lowering the melting point of the melting point depressant is manifested even when added in a small amount. However, although a large amount of addition can sufficiently achieve the effect of lowering the melting point, the amount of granulated particles derived from converter slag increases, and the processing capacity of existing granulators such as pelletizers is small. Grain equipment is required, which may lead to an increase in equipment costs. Therefore, in the present invention, the melting point depressant added to the converter slag is less than 1 in mass ratio to the converter slag. In addition, although the effect of melting | fusing point fall is acquired if it exceeds 0, in order to reduce melting | fusing point reliably, it is preferable to add 0.20 or more by mass ratio with respect to converter slag.
ここで、転炉スラグに添加する上記融点降下剤としては、ＣａＯを主成分とするフラックスおよび／またはＦｅを主成分とするフラックスを用いることができる。
ＣａＯを主成分とするフラックスとしては、ＣａＯを４０ｍａｓｓ％以上含有するものが好ましく、具体的には、石灰石や生石灰、脱硫スラグ等を挙げることができる。これらを用いる場合の添加量は、転炉スラグに対するフラックス中に含まれるＣａＯの質量比で０．２５以下の範囲とするのが好ましい。０．２５以下の添加で十分な効果が得られる一方で、過剰の添加は転炉スラグ由来の造粒粒子の造粒負荷が高まるからである。なお、添加効果は０超えであれば得られるが、融点の低下効果を確実に得るためには、転炉スラグの融点の高低によっても変わるが、０．０５以上とするのがより好ましい。
Here, as the melting point depressant added to the converter slag, a flux mainly composed of CaO and / or a flux mainly composed of Fe can be used.
As the flux mainly composed of CaO, a flux containing 40 mass% or more of CaO is preferable, and specific examples include limestone, quicklime and desulfurized slag. When using these, it is preferable to make the addition amount into the range of 0.25 or less by the mass ratio of CaO contained in the flux with respect to converter slag. This is because a sufficient effect can be obtained with addition of 0.25 or less, while excessive addition increases the granulation load of the granulated particles derived from the converter slag. In addition, although the addition effect is obtained if it exceeds 0, in order to surely obtain the melting point lowering effect, it varies depending on the melting point of the converter slag, but is more preferably 0.05 or more.
また、上記ＣａＯを主成分とするフラックスとして、脱硫工程で発生する脱硫スラグを用いた場合は、転炉スラグの使用量を減らすことなく製鋼スラグである脱硫スラグを追加利用できるので、製鋼スラグの再利用をさらに拡大することが可能となる。 In addition, when the desulfurization slag generated in the desulfurization process is used as the flux mainly composed of CaO, desulfurization slag, which is steelmaking slag, can be additionally used without reducing the amount of converter slag used. Reuse can be further expanded.
一方、Ｆｅを主成分とするフラックスとしては、具体的には、Ｆｅを５０ｍａｓｓ％以上含有するものが好ましく、ミルスケールや鉄鉱石、転炉ダスト、焼結ダスト、焼結返鉱等を挙げることができる。これらを用いる場合の添加量は、転炉スラグに対するフラックス中に含まれるＦｅを質量比で０．３５以下の範囲とするのが好ましい。０．３５以下の添加で十分な効果が得られる一方で、過剰の添加は転炉スラグ由来の造粒粒子の造粒負荷が高まるからである。なお、添加効果は０超えであれば得られるが、融点の低下効果を確実に得るためには、転炉スラグの融点の高低によっても変わるが、０．０５以上とするのがより好ましい。 On the other hand, as a flux mainly composed of Fe, specifically, a flux containing 50 mass% or more of Fe is preferable, and examples include mill scale, iron ore, converter dust, sintered dust, sintered ore, and the like. Can do. When these are used, it is preferable that the amount of Fe contained in the flux with respect to the converter slag is in a range of 0.35 or less in terms of mass ratio. This is because a sufficient effect can be obtained with addition of 0.35 or less, while excessive addition increases the granulation load of granulated particles derived from converter slag. In addition, although the addition effect is obtained if it exceeds 0, in order to surely obtain the melting point lowering effect, it varies depending on the melting point of the converter slag, but is more preferably 0.05 or more.
また、転炉スラグに添加する融点降下剤として、ＣａＯを主成分とするフラックスとＦｅを主成分とするフラックスを併用する場合には、両フラックスの転炉スラグに対する質量比が１未満の条件を満たす限り、それぞれを上記した範囲で添加することができる。 In addition, as a melting point depressant to be added to the converter slag, when a flux mainly composed of CaO and a flux mainly composed of Fe are used in combination, the mass ratio of both fluxes to the converter slag is less than 1. As long as it is satisfied, each of them can be added within the above range.
次に、本発明における転炉スラグ由来の造粒粒子と、転炉スラグ以外の原料由来の造粒粒子の造粒方法と、上記転炉スラグ由来の造粒粒子を転炉スラグ以外の原料由来の造粒粒子中に分散させて焼結機に装入する方法について説明する。
転炉スラグ以外の造粒原料は、図２の上段に示したように、混合ミキサーで均一に混合し、造粒用ドラムミキサーに供給して造粒粒子（擬似粒子）とした後、ベルトコンベア等で焼結機に搬送する。一方、転炉スラグは、必要な融点降下剤を添加して均一に混合した後、図２の下段に示したように、ペレタイザ等を用いて転炉スラグ以外の原料由来の造粒粒子より大きな粒子径の造粒粒子に造粒した後、ベルトコンベア等で焼結機搬送する。
Next, the granulated particles derived from the converter slag in the present invention, the granulation method of the granulated particles derived from the raw materials other than the converter slag, and the granulated particles derived from the converter slag derived from the raw materials other than the converter slag A method of dispersing in the granulated particles and charging the sintered machine will be described.
As shown in the upper part of FIG. 2, the granulation raw material other than the converter slag is uniformly mixed with a mixing mixer, supplied to a granulation drum mixer to form granulated particles (pseudo particles), and then a belt conveyor. Etc. to the sintering machine. On the other hand, the converter slag is larger than the granulated particles derived from raw materials other than the converter slag using a pelletizer or the like, as shown in the lower part of FIG. After granulating the granulated particles with a particle diameter, the particles are conveyed to a sintering machine by a belt conveyor or the like.
上記のようにして得た転炉スラグ由来の造粒粒子は、転炉スラグ以外の原料由来の造粒粒子中に均一に分散させて焼結機のパレットに装入する。この方法としては、例えば、ベルトコンベアで搬送中の転炉スラグ以外の原料由来の造粒粒子上に、転炉スラグ由来の造粒粒子を払い出して積層状態とした後、あるいは逆に、ベルトコンベアで搬送中の転炉スラグ由来の造粒粒子上に転炉スラグ以外の原料由来の造粒粒子を払い出したりして積層状態とした後、焼結原料を一時貯留しておくサージホッパに搬入して、このサージホッパ内で混合する方法、上記積層状態にした造粒粒子をベルトコンベアで搬送中に、ジャンクション（乗り継ぎ）部分で２種類の造粒粒子を混合させる方法、混合用ドラムミキサーを別途設置し、このミキサーで上記２種類の造粒粒子を混合する方法等を好ましく挙げることができる。 The granulated particles derived from the converter slag obtained as described above are uniformly dispersed in the granulated particles derived from the raw materials other than the converter slag and charged into the pallet of the sintering machine. As this method, for example, the granulated particles derived from the raw material other than the converter slag that is being conveyed by the belt conveyor are put out on the granulated particles from the converter slag to form a laminated state, or conversely, After putting the granulated particles derived from the raw materials other than the converter slag into a laminated state on the granulated particles derived from the converter slag that is being transported in, it is carried into a surge hopper that temporarily stores the sintered raw material , A method of mixing in the surge hopper, a method of mixing two types of granulated particles at the junction (transfer) while conveying the granulated particles in the above laminated state on a belt conveyor, and a drum mixer for mixing are separately installed. A method of mixing the above-mentioned two types of granulated particles with this mixer is preferable.
なお、上記に説明した造粒方法や装入方法は、単なる例示であり、他の方法を用いてもよいことは勿論である。 Note that the granulation method and the charging method described above are merely examples, and it is needless to say that other methods may be used.
表１に示した、融点が比較的高めの転炉スラグＢおよびＣと、表３に示した、各種の造粒原料を準備し、これらの原料を転炉スラグと転炉スラグ以外の原料とに分別し、下記の方法で造粒粒子とした。
・比較例１，２：分別した造粒原料を均一に混合した後、図１に示した混合造粒法で造粒粒子とした。なお、上記造粒粒子の粒子径は、質量平均粒子径は３．１ｍｍであった。
・発明例１〜１０：転炉スラグと転炉スラグ以外とに分別した造粒原料を、図２に示した分別造粒法で造粒し、転炉スラグ以外の造粒粒子および転炉スラグ由来の造粒粒子とした。なお、転炉スラグ以外の造粒粒子の粒子径は質量平均で３．２ｍｍ、転炉スラグ由来の造粒粒子の粒子径は質量平均で４．８ｍｍ（１．５倍）であった。
The converter slags B and C having relatively high melting points shown in Table 1 and various granulated raw materials shown in Table 3 were prepared, and these raw materials were converted into converter slag and raw materials other than the converter slag. And granulated particles by the following method.
Comparative Examples 1 and 2: After the classified granulated raw material was uniformly mixed, granulated particles were obtained by the mixed granulation method shown in FIG. The granulated particles had a mass average particle size of 3.1 mm.
Invention Examples 1 to 10: Granulated raw materials fractionated into converter slag and other than converter slag are granulated by the fractional granulation method shown in FIG. 2, and granulated particles other than converter slag and converter slag The resulting granulated particles were used. The particle diameter of the granulated particles other than the converter slag was 3.2 mm in terms of mass average, and the particle diameter of the granulated particles derived from the converter slag was 4.8 mm (1.5 times) in terms of mass average.
次いで、上記のようにして得た造粒粒子を焼結原料とし、先述した実験と同じ、内径が２９０ｍｍφ、高さが４００ｍｍの焼結試験鍋を用いて焼結実験を行った。
焼結実験は、比較例１，２の場合には、混合造粒法で造粒した造粒粒子をそのまま焼結原料として試験鍋に充填し、一方、発明例１〜１０の場合には、図３に示したように、転炉スラグ由来の造粒粒子が、転炉スラグ以外の原料由来の造粒粒子中に均一に分散するように試験鍋に充填し、その後、充填層の最表面に点火し、試験鍋の下方でブロアを用いて一定圧力で吸引して空気を充填層内に導入することにより行った。なお、上記焼結実験では、焼結に要した時間と、得られた焼結鉱（焼結ケーキ）の成品歩留り（焼結実験で得られた焼結ケーキを破砕し、篩い分けしたときの粒径が１０ｍｍ以上の粒子の質量％）を測定し、これらの値から焼結鉱の生産率を求めた。
Next, the granulated particles obtained as described above were used as a sintering raw material, and a sintering experiment was performed using a sintering test pot having an inner diameter of 290 mmφ and a height of 400 mm, which was the same as the experiment described above.
In the case of Comparative Examples 1 and 2, the sintering experiment was performed by filling the granulated particles granulated by the mixed granulation method into the test pot as a raw material as it was, while in the case of Invention Examples 1 to 10, As shown in FIG. 3, the test pan is filled so that the granulated particles derived from the converter slag are uniformly dispersed in the granulated particles derived from the raw materials other than the converter slag, and then the outermost surface of the packed bed Was ignited and sucked at a constant pressure using a blower below the test pan to introduce air into the packed bed. In the above sintering experiment, the time required for sintering and the product yield of the obtained sintered ore (sintered cake) (when the sintered cake obtained in the sintering experiment was crushed and sieved) The mass percentage of particles having a particle size of 10 mm or more) was measured, and the production rate of sintered ore was determined from these values.
上記焼結実験の生産率の結果を表３に併記した。
同じ造粒原料を用いた比較例１と発明例１との比較、および、比較例２と発明例６との比較から、転炉スラグと転炉スラグ以外の造粒原料を均一に混合して造粒した造粒粒子をそのまま試験鍋に装入した比較例よりも、転炉スラグと転炉スラグ以外の造粒原料とを分別し、それぞれを別々に造粒した後、転炉スラグ由来の造粒粒子を転炉スラグ以外の原料由来の造粒粒子中に分散させて試験鍋中に装入した発明例の方が、焼結鉱の生産率が向上していることがわかる。
さらに、発明例１と発明例２、３および５との比較、および、発明例６と発明例７、８との比較から、転炉スラグに、転炉スラグに対する質量比で１未満のフラックス（融点降下剤）を添加した場合には、焼結鉱の生産率がさらに向上していることがわかる。この理由は、転炉スラグにフラックスを添加したことによって、転炉スラグ由来の造粒粒子の融点が低下し、焼結鉱の強度が向上したためと推察される。
また、発明例１と発明例４との比較、および、発明例６と発明例９，１０との比較から、フラックスとして製鋼スラグの１種である脱硫スラグを添加しても、同様の効果が得られること、また、この場合には、転炉スラグと脱硫スラグの合計である製鋼スラグ使用量を、転炉スラグ単味のときの１．５倍に増やしても、焼結鉱の生産率にはほとんど悪影響を及ぼさないことがわかる。
上記実験の結果から、本発明によれば、焼結機の生産性を害することなく、焼結原料として製鋼スラグを再利用することができることが確認された。
The results of the production rate of the sintering experiment are also shown in Table 3.
From comparison between Comparative Example 1 and Invention Example 1 using the same granulated raw material, and comparison between Comparative Example 2 and Invention Example 6, granulated raw materials other than converter slag and converter slag were mixed uniformly. Compared to the comparative example in which the granulated granulated particles are charged into the test pan as they are, the converter slag and the granulated raw material other than the converter slag are separated and granulated separately, and then derived from the converter slag. It can be seen that the inventive example in which the granulated particles are dispersed in the granulated particles derived from raw materials other than the converter slag and charged into the test pan has an improved production rate of sintered ore.
Furthermore, from the comparison between Invention Example 1 and Invention Examples 2, 3 and 5, and the comparison between Invention Example 6 and Invention Examples 7 and 8, the converter slag was given a flux less than 1 in mass ratio to the converter slag ( It can be seen that when the melting point depressant is added, the production rate of sintered ore is further improved. This is presumably because the melting point of the granulated particles derived from the converter slag was lowered and the strength of the sintered ore was improved by adding the flux to the converter slag.
Moreover, even if it adds desulfurization slag which is 1 type of steelmaking slag as a flux from the comparison with invention example 1 and invention example 4 and the comparison with invention example 6 and invention example 9 and 10, the same effect is obtained. In this case, even if the amount of steelmaking slag, which is the sum of converter slag and desulfurization slag, is increased to 1.5 times the converter slag alone, the production rate of sintered ore It can be seen that there is almost no adverse effect.
From the results of the above experiments, it was confirmed that according to the present invention, steelmaking slag can be reused as a sintering raw material without harming the productivity of the sintering machine.
Claims (7)
前記焼結原料の一部として転炉スラグを用いる際、転炉スラグと転炉スラグ以外の原料とを分別し、それぞれを別々に造粒して転炉スラグ由来の造粒粒子と転炉スラグ以外の原料由来の造粒粒子とするとともに、
前記転炉スラグ由来の造粒粒子を、造粒原料に転炉スラグに対して質量比で１未満の融点降下剤を添加し、かつ、質量平均径が転炉スラグ以外の原料由来の造粒粒子以上となるように造粒した上で、転炉スラグ以外の原料由来の造粒粒子中に分散させてパレット上に装入することを特徴とする焼結鉱の製造方法。 A granulated raw material mainly composed of iron ore, CaO-based auxiliary material, SiO 2 -based auxiliary material, return ore and solid fuel is granulated into granulated particles, which are used as sintering raw materials on the pallet of the sintering machine In a method of charging and sintering to produce a sintered ore,
When using converter slag as a part of the sintering raw material, the converter slag and the raw material other than the converter slag are separated, and each is granulated separately to form granulated particles derived from the converter slag and the converter slag. With granulated particles derived from other raw materials,
The granulated particles derived from the converter slag are added to a granulated raw material with a melting point depressant having a mass ratio of less than 1 with respect to the converter slag, and the mass average diameter is derived from a raw material other than the converter slag. A method for producing a sintered ore, characterized by being granulated so as to be equal to or larger than particles and then being dispersed in granulated particles derived from raw materials other than converter slag and charged on a pallet.
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