JP3709001B2 - Non-fired agglomerated ore for iron making and method of using the same - Google Patents

Description

【００１４】
図２に核粒子に従来の砂鉄を使用したベースのペレット（図中○印）と核粒子に焼結鉱を使用した配合１と配合２のペレット（図中■は配合１、▲は配合２のペレット）を示す。各ペレットは１０００℃でＣＯ／ＣＯ₂ ＝５０％／５０％の混合ガスと平衡させ、２８％の還元率が得られるように事前に予備処理を施した。ＣＯガス３０％、Ｎ₂ ガス７０％の混合ガスを７℃／ｍｉｎの割合で昇温し、各ペレットの予備還元を行った。図２にその結果を示す。
【００１５】
図２により、還元ガスによるペレットの還元率を各温度で比較すると、ベースのペレットに比べ、焼結鉱を核粒子に採用した配合１、配合２のペレットの方が還元率が高いことが確認できる。特に、粒径３ｍｍ以下の細粒焼結鉱を核粒子として配合した配合１のペレットは、１２００℃以上ではベースのペレットに比べ、還元率において５％以上の差がみられる。また、粒径５ｍｍ以下の細粒焼結鉱を核粒子として配合した配合２のペレットでも還元率が改善していることがわかる。
【００１６】
次に、高炉での使用試験においても顕著な改善がみられた。すなわち、表２に示す高炉Ａはベル炉、高炉Ｂはベルレス炉であり、両者ともに同じ燃料比レベルで操業した。両高炉共に高炉装入原料に占めるベースのペレットの配合率は５ｗｔ％とした。表２に粒径３ｍｍ以下の細粒焼結鉱を核粒子として使用した配合１のペレットを使用した場合とベースのペレットを使用した場合の操業緒元を示す。配合１のペレットでは両高炉共に塊状帯での間接還元率がベースのペレットの場合よりも向上し、ηＣＯが上昇した。また、還元率改善により熱レベルに余裕ができ、燃料比も低下した。しかも、配合１のペレットには細粒焼結鉱が含まれているので、細粒焼結鉱を高炉で消費できたことになる。
【００１７】
【表２】

【００１８】
【発明の効果】
本発明の製鉄用非焼成塊成鉱は、従来の非焼成塊成鉱に比べて、飛躍的に被還元性状が改善される。また、高炉で細粒焼結鉱を使用可能とする。
【図面の簡単な説明】
【図１】製鉄用非焼成塊成鉱の構造を示す図である。
【図２】還元ガスによりペレットを還元したときの温度と間接還元率との関係を示す図である。
【符号の説明】
１ 核粒子
２ 外周層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a non-fired agglomerated ore for iron making blended with fine-grained sintered ore and a method for using the same.
[0002]
[Prior art]
A typical example of the non-fired agglomerated ore for iron making is a cold pellet using a hydraulic binder such as cement as a binder. Such cold pellets are usually manufactured using iron ore such as iron sand as a raw material, of which massive particles having a relatively large particle diameter are adopted as core particles 1 as shown in FIG. The mixture of the material and the auxiliary material is made into a double structure by granulating the core particle 1 with a pan pelletizer. On the other hand, in order to maintain the conveying strength of the cold pellets, the binder may be increased. However, from the viewpoint of cost, the present condition is that the composition is minimum. Therefore, in order to maintain this strength, particles having a certain degree of strength are inserted as the core particles 1. Generally, lump particles of ore such as iron sand which is not preferable as a sintering compounding raw material are used as the core particles 1.
[0003]
In this case, the outer peripheral layer 2 is formed of a mixture of fine ore, blast furnace ash, charcoal, etc., whereas the core particle 1 is often a single particle, and the ore itself is not porous. Since the porosity is low, it is difficult to pass the reducing gas. Moreover, the center part of the non-baking agglomerated mineral in which the core particles 1 are present is the farthest distance from the pellet surface, which is the contact point with the reducing gas, and is therefore the part where the reducing gas is most difficult to reach. That is, usually, when reducing the uncalcined agglomerated mineral with a reducing gas, the reduction starts from the surface layer in which the uncalcined agglomerated mineral and the reducing gas are in direct contact and gradually progresses to the inside. For this reason, the reduction proceeds faster in the outer peripheral layer 2 and the reduction rate becomes higher, but the reducing gas does not easily reach the central portion, and in an extreme case, the reduction proceeds by direct reduction. If a single particle of ore such as iron sand is used as the core particle 1 in the central part, the reducing gas does not pass through the particle central part. As a result, the reducing gas is blocked by the core particles 1 in the center portion of the unfired agglomerated mineral, and the reduction in the center portion is delayed most.
[0004]
Thus, in order to increase the reduction efficiency of the entire unfired agglomerated ore, it is necessary to improve the reduction efficiency of the pellet center where the reduction is most delayed. On the other hand, there have already been attempts to improve quality by adjusting the whole manufacturing process and blending as disclosed in JP-A-52-119403 and JP-A-62-192596. However, even though the reduction efficiency of the outer peripheral layer of the non-fired agglomerated mineral can be improved, it is not a means for directly improving the reduction efficiency of the pellet center. Moreover, since these techniques involve improvement of the manufacturing process, the burden is high in cost.
[0005]
On the other hand, fine-grained sintered ore is also generated in blast furnaces and sintering factories. Conventionally, after taking a simple granulation treatment, it is sent back to the sintering factories and newly used as a sintering raw material. Fine-grained sinter was originally generated when sinter was produced in a sinter plant, or when sinter produced in a sinter plant was transported, or as blast furnace powder. is there. However, when this fine-grained sintered ore is newly used as a raw material for sinter ore blending at a sintering plant, there is a problem that the production yield of the sintering plant becomes very low (usually 15% is fine-grained). Returned to sinter plant as sinter).
[0006]
Also, even when trying to use fine-grained sinter in the blast furnace, because the fine-grained sinter itself is fine, when inserted in the blast furnace furnace, the porosity of the ore layer will be significantly reduced, Therefore, at present, it is difficult to use fine-grained sintered ore with a particle size of 5 mm or less. In some blast furnaces, re-sieving of the under-floor powder is carried out, and a relatively large particle size of 5 to 2 mm is taken out from the powder of 5 mm or less and charged into the blast furnace. However, there is a limit to the amount that can be charged, and the generated fine-grained sinter cannot be digested in its entirety.
[0007]
[Problems to be solved by the invention]
The conventional technique is mainly a method for improving the reduction efficiency of the outer peripheral layer of the non-calcined agglomerate that can be handled relatively advantageously, and there is no method for improving the reduction efficiency of the central portion where the reduction is most delayed. An object of the present invention is to improve the reduction efficiency of a non-fired agglomerated ore by improving the reduction efficiency of the pellet center where the reduction is most delayed. Further, the fine particle sintered ore and an object thereof is to enable digestion with blast furnace.
[0008]
[Means for Solving the Problems]
The present invention considers the following two points in order to solve the above problems. That is, (1) particle size was higher following porosity particle diameter 3mm sintered ore in that you use as core particles in the center of the non-calcined mass Naruko of 5 to 20 mm. Thereby , reducing gas can pass to the center part of a non-baking agglomerated mineral, and the reduction efficiency of the whole non-baking agglomerated mineral improves. Furthermore, ( 2 ) by granulating fine-grained sintered ore, fine-grained ore having a particle diameter of 3 mm or less, which is difficult to use in a blast furnace, can be used in the blast furnace without any problems.
[0009]
Therefore, the non-fired agglomerated ore for iron making of the present invention uses fine sintered ore having a particle size of 3 mm or less as core particles, and the outer peripheral layer surrounding the core particles is made of dust containing iron raw materials and carbonaceous materials, and It was composed of three mixtures of binder composed of cement, a granulated product having a particle diameter 5 to 20 mm. Its to uses steel for non-calcined mass Naruko of the present invention having such characteristics as charging a raw material for blast furnace or converter.
[0010]
In the present invention, instead of ore such as iron sand, porous and high-porosity sintered ore is adopted as the core particles, so that the reducing gas can easily flow into the center of the unfired agglomerated ore. Improve the reduction rate. As described above, since the reduction rate in the central portion is the lowest, the improvement in the reduction efficiency at this portion leads to the improvement in the reduction rate of the whole pellet. In addition, in many cases, fine sintered ore having a particle size of 3 mm or less, which is not used as a sieve in a blast furnace, is granulated into particles having a particle size exceeding 5 mm, so that it can be used in a blast furnace.
【Example】
Hereinafter, the present invention will be described in more detail based on examples.
[0012]
Table 1 shows the blending of the pellets. The base is a conventional blend, using iron sand as core particles, Formula 1 using fine sinter with a particle size of 3 mm or less for the core particles, Formula 2 using fine particles with a particle size of 5 mm or less for the core particles Sintered ore was used, and all of them were sieved and a granulated product having a particle size of 5 to 20 mm was used for the test.
[0013]
[Table 1]

[0014]
Fig. 2 shows pellets based on conventional sand iron as core particles (marked with a circle in the figure) and blends 1 and 2 using sintered ore as the core particles (■ in the figure is compound 1 and ▲ is compound 2) Pellets). Each pellet was equilibrated with a mixed gas of CO / CO ₂ = 50% / 50% at 1000 ° C. and pretreated in advance so as to obtain a reduction rate of 28%. A mixed gas of 30% CO gas and 70% N ₂ gas was heated at a rate of 7 ° C./min to perform preliminary reduction of each pellet. The results are shown in FIG.
[0015]
According to Fig. 2, when the reduction rate of pellets with reducing gas is compared at each temperature, it is confirmed that the pellets of compound 1 and compound 2 using sintered ore as the core particles have a higher reduction rate than the base pellets. it can. In particular, pellets of Formulation 1 in which fine sintered ore having a particle diameter of 3 mm or less is blended as core particles show a difference of 5% or more in reduction rate at 1200 ° C. or higher compared to the base pellet. Moreover, it turns out that the reduction rate is improving also with the pellet of the mixing | blending 2 which mix | blended the fine grain sintered ore with a particle size of 5 mm or less as a core particle.
[0016]
Next, a remarkable improvement was also observed in the use test in the blast furnace. That is, the blast furnace A shown in Table 2 was a bell furnace, and the blast furnace B was a bellless furnace, both of which operated at the same fuel ratio level. In both blast furnaces, the blending ratio of the base pellets in the blast furnace charge was 5 wt%. Table 2 shows the operating conditions in the case of using the pellets of Formula 1 using fine sinter having a particle diameter of 3 mm or less as the core particles and in the case of using the base pellets. In the pellets of Formulation 1, the indirect reduction rate in the massive band was improved in both blast furnaces compared to the case of the base pellets, and ηCO was increased. In addition, the improvement of the reduction rate allowed the heat level to be surpassed and the fuel ratio also decreased. And since the pellet of the mixing | blending 1 contains the fine grain sintered ore, the fine grain sintered ore could be consumed in the blast furnace.
[0017]
[Table 2]

[0018]
【The invention's effect】
The non-calcined agglomerated ore for iron making according to the present invention is remarkably improved in reducible properties as compared with the conventional non-calcined agglomerated ore. In addition, fine sinter can be used in the blast furnace.
[Brief description of the drawings]
FIG. 1 is a diagram showing the structure of an unfired agglomerated ore for iron making.
FIG. 2 is a graph showing the relationship between temperature and indirect reduction rate when pellets are reduced with reducing gas.
[Explanation of symbols]
1 Core particle 2 Outer layer

Claims (2)

The following fine sintered ore particle size 3 mm and core particles, a peripheral layer surrounding the core particles, dust containing iron raw material and carbonaceous material, and the particle size constituted of a mixture of a binder consisting of cement 5 to 2 A non-fired agglomerated ore for iron making, which is a granulated product of 0 mm . Using steel for non-calcined mass Naruko, characterized by the use of steel for non-calcined mass Naruko according as charging a raw material of high furnace to claim 1.

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